U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

OCS EIS/EA

BOEM 2017-009

Gulf of Mexico OCS 

Oil and Gas Lease Sales: 2017-2022

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

254, 256, 257, 259, and 261

Final Multisale Environmental Impact Statement

Volume II: Chapters 4-8 

U.S. Department of the Interior

Bureau of Ocean Energy Management Gulf of Mexico OCS Region

OCS EIS/EA

BOEM 2017-009

Gulf of Mexico OCS 

Oil and Gas Lease Sales: 2017-2022

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

254, 256, 257, 259, and 261

Final Multisale Environmental Impact Statement

Volume II: Chapters 4-8 

Author

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

Published by

New Orleans

March 2017

Table of Contents iii

TABLE OF CONTENTS

Volume I

Page

EXECUTIVE SUMMARY ..................................................................................................................... vii

LIST OF FIGURES................................................................................................................................liii

LIST OF TABLES................................................................................................................................lxiii

ABBREVIATIONS AND ACRONYMS ...............................................................................................lxvii

CONVERSION CHART ....................................................................................................................lxxiii

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

1.0 Introduction............................................................................................................................. 1-3

1.1 Purpose of the Proposed Actions........................................................................................... 1-5

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

1.3 OCS Oil and Gas Program Planning and Decision Process ................................................. 1-7

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

1.3.1.1 Five-Year Program of Proposed OCS Lease Sales .................................. 1-8

1.3.1.2 Individual Lease Sale Consultation and Decision Process...................... 1-10

1.3.2 Gulf of Mexico Postlease Activities.......................................................................... 1-12

1.4 The Decision To Be Made.................................................................................................... 1-13

1.5 Regulatory Framework ......................................................................................................... 1-13

1.6 Other OCS Oil- and Gas-Related Activities ......................................................................... 1-15

1.7 Other Pertinent Environmental Reviews or Documentation ................................................ 1-18

1.8 Format and Organization of the Multisale EIS ..................................................................... 1-22

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

2.0 Introduction............................................................................................................................. 2-3

2.1 Multisale NEPA Analysis ........................................................................................................ 2-4

2.2 Alternatives, Mitigating Measures, and Issues....................................................................... 2-5

2.2.1 What is the 2017-2022 Proposed Lease Sale Schedule?......................................... 2-5

2.2.2 What are the Alternatives that BOEM is Considering for Each Proposed 

Lease Sale? ............................................................................................................... 2-6

2.2.2.1 Alternative A—Regionwide OCS Lease Sale (The Preferred 

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

2.2.2.2 Alternative B—Regionwide OCS Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale 

Area ............................................................................................................ 2-8

2.2.2.3 Alternative C—Regionwide OCS Lease Sale Excluding Available 

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

Sale Area.................................................................................................... 2-9

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

Available Unleased Blocks Subject to the Topographic Features, 

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

Alabama, Stipulations............................................................................... 2-10

2.2.2.5 Alternative E—No Action.......................................................................... 2-13
iv Gulf of Mexico Multisale EIS

2.2.3 What Other Alternatives and Deferrals have BOEM Considered but 

Not Analyzed in Detail?............................................................................................ 2-14

2.2.4 What Types of Mitigating Measures Does BOEM Apply? ....................................... 2-23

2.2.4.1 Proposed Lease Mitigating Measures (Stipulations) ............................... 2-24

2.2.4.2 Prelease Mitigating Measures (Stipulations) by Alternative .................... 2-28

2.2.4.3 Postlease Mitigating Measures ................................................................ 2-29

2.2.5 What are the Primary Topics and Resources Being Evaluated? ............................ 2-31

2.2.5.1 Issues to be Analyzed .............................................................................. 2-31

2.2.5.2 Issues Considered but Not Analyzed....................................................... 2-34

2.3 Comparison of Impacts by Alternative ................................................................................. 2-35

2.4 Summary of Impacts............................................................................................................. 2-37

2.4.1 Air Quality................................................................................................................. 2-37

2.4.2 Water Quality ........................................................................................................... 2-39

2.4.3 Coastal Habitats....................................................................................................... 2-39

2.4.3.1 Estuarine Systems (Wetlands and Seagrasses/Submerged 

Vegetation) ............................................................................................... 2-39

2.4.3.2 Coastal Barrier Beaches and Associated Dunes..................................... 2-40

2.4.4 Deepwater Benthic Communities ............................................................................ 2-41

2.4.5 Sargassum and Associated Communities............................................................... 2-41

2.4.6 Live Bottoms ............................................................................................................ 2-42

2.4.6.1 Topographic Features .............................................................................. 2-42

2.4.6.2 Pinnacles and Low-Relief Features ......................................................... 2-42

2.4.7 Fish and Invertebrate Resources............................................................................. 2-43

2.4.8 Birds ......................................................................................................................... 2-44

2.4.9 Protected Species.................................................................................................... 2-44

2.4.9.1 Marine Mammals...................................................................................... 2-44

2.4.9.2 Sea Turtles ............................................................................................... 2-45

2.4.9.3 Beach Mice............................................................................................... 2-46

2.4.9.4 Protected Birds......................................................................................... 2-46

2.4.9.5 Protected Corals....................................................................................... 2-47

2.4.10 Commercial Fisheries .............................................................................................. 2-47

2.4.11 Recreational Fishing ................................................................................................ 2-48

2.4.12 Recreational Resources........................................................................................... 2-48

2.4.13 Archaeological Resources ....................................................................................... 2-49

2.4.14 Human Resources and Land Use (Including Environmental Justice)..................... 2-50

2.4.14.1 Land Use and Coastal Infrastructure ....................................................... 2-50

2.4.14.2 Economic Factors..................................................................................... 2-50

2.4.14.3 Social Factors (Including Environmental Justice).................................... 2-51

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

3.0 Introduction............................................................................................................................. 3-3

3.1 Impact -Producing Factors and Scenario—Routine Operations............................................ 3-6

3.1.1 Resource Estimates and Timetables......................................................................... 3-6

3.1.2 Exploration and Delineation..................................................................................... 3-11

3.1.2.1 Geological and Geophysical Surveys ...................................................... 3-11

3.1.2.2 Exploration and Delineation Plans and Drilling........................................ 3-17

3.1.3 Offshore Development and Production.................................................................... 3-22

3.1.3.1 Development and Production Drilling....................................................... 3-22

3.1.3.2 Offshore Production Systems .................................................................. 3-29
Table of Contents v 

3.1.3.3 Infrastructure Emplacement/Structure Installation and Commissioning 

Activities ................................................................................................... 3-33

3.1.3.3.1 Pipelines ................................................................................ 3-37

3.1.3.3.2 Bottom-Area Disturbance ...................................................... 3-42

3.1.3.3.3 Sediment Displacement......................................................... 3-44

3.1.3.3.4 Navigation Channels ............................................................. 3-45

3.1.3.4 Infrastructure Presence............................................................................ 3-50

3.1.3.4.1 Anchoring............................................................................... 3-50

3.1.3.4.2 Space-Use Requirements ..................................................... 3-50

3.1.3.4.3 Structure Lighting .................................................................. 3-51

3.1.3.5 Workovers and Abandonments................................................................ 3-52

3.1.4 Transport.................................................................................................................. 3-53

3.1.4.1 Barges ...................................................................................................... 3-53

3.1.4.2 Oil Tankers ............................................................................................... 3-53

3.1.4.3 Service Vessels........................................................................................ 3-55

3.1.4.4 Helicopters................................................................................................ 3-56

3.1.5 Discharges and and Wastes.................................................................................... 3-58

3.1.5.1 Operational Wastes and Discharges Generated by OCS Oil- and 

Gas-Related Facilities .............................................................................. 3-58

3.1.5.1.1 Drilling Muds and Cuttings..................................................... 3-62

3.1.5.1.2 Produced Waters................................................................... 3-66

3.1.5.1.3 Well-Treatment, Workover, and Completion Fluids .............. 3-69

3.1.5.1.4 Production Solids and Equipment ......................................... 3-70

3.1.5.1.5 Bilge, Ballast, and Fire Water................................................ 3-71

3.1.5.1.6 Cooling Water........................................................................ 3-71

3.1.5.1.7 Deck Drainage....................................................................... 3-72

3.1.5.1.8 Treated Domestic and Sanitary Wastes................................ 3-72

3.1.5.1.9 Minor/Miscellaneous Discharges........................................... 3-73

3.1.5.2 Operational Wastes and Discharges Generated by Service Vessels ..... 3-73

3.1.5.3 Onshore Disposal of Waste and Discharge Generated Offshore or 

Onshore.................................................................................................... 3-74

3.1.5.3.1 Onshore Disposal of Wastes Generated from OCS Oiland Gas-Related Facilities .................................................... 3-74

3.1.5.3.2 Onshore Disposal and Storage Facilities Supporting 

OCS-Generated Operational Wastes.................................... 3-75

3.1.5.3.3 Discharges from Onshore Support Facilities......................... 3-76

3.1.6 Decommissioning and Removal Operations ........................................................... 3-76

3.1.6.1 Structure Age and Idle Iron ...................................................................... 3-79

3.1.6.2 Artificial Reefs........................................................................................... 3-81

3.1.7 Coastal Infrastructure............................................................................................... 3-81

3.1.7.1 Construction Facilities .............................................................................. 3-84

3.1.7.1.1 Platform Fabrication Yards.................................................... 3-84

3.1.7.1.2 Shipbuilding and Shipyards................................................... 3-84

3.1.7.1.3 Pipe-Coating Facilities and Yards ......................................... 3-85

3.1.7.2 Support Facilities and Transportation ...................................................... 3-86

3.1.7.2.1 Service Bases and Ports ....................................................... 3-86

3.1.7.2.2 Helicopter Hubs ..................................................................... 3-88

3.1.7.2.3 Tanker Port Areas ................................................................. 3-88

3.1.7.2.4 Barge Terminals .................................................................... 3-89

3.1.7.2.5 Pipeline Shore Facilities ........................................................ 3-89

3.1.7.2.6 Waste Disposal Facilities....................................................... 3-89

3.1.7.2.7 Natural Gas Storage Facilities............................................... 3-90
vi Gulf of Mexico Multisale EIS

3.1.7.3 Processing Facilities................................................................................. 3-90

3.1.7.3.1 Gas Processing Plants .......................................................... 3-90

3.1.7.3.2 Refineries............................................................................... 3-91

3.1.7.3.3 Onshore Liquefied Natural Gas Facilities.............................. 3-91

3.1.7.3.4 Petrochemical Plants............................................................. 3-92

3.1.8 Air Emissions ........................................................................................................... 3-92

3.1.8.1 Drilling....................................................................................................... 3-94

3.1.8.2 Production ................................................................................................ 3-94

3.1.8.3 Vessel Support Operations and Activities during Offshore Oil and 

Gas Activities............................................................................................ 3-94

3.1.8.4 Flaring and Venting .................................................................................. 3-95

3.1.8.5 Fugitive Emissions ................................................................................... 3-96

3.1.8.6 Greenhouse Gases .................................................................................. 3-96

3.1.8.7 Decommissioning..................................................................................... 3-96

3.1.9 Noise ........................................................................................................................ 3-96

3.1.10 New and Unusual Technology................................................................................. 3-99

3.2 Impact-Producing Factors and Scenario—Accidental Events ...........................................3-101

3.2.1 Oil Spills .................................................................................................................3-101

3.2.1.1 Past OCS Spills......................................................................................3-101

3.2.1.1.1. Trends in Reported Spill Volumes and Numbers................3-101

3.2.1.1.2 Coastal Spills.......................................................................3-106

3.2.1.1.3 Offshore Spills .....................................................................3-110

3.2.1.2 Characteristics of OCS Oil .....................................................................3-116

3.2.1.3 Transport and Fate of Offshore Spills....................................................3-117

3.2.1.4 Analysis of Offshore Spills ≥1,000 bbl ...................................................3-120

3.2.1.4.1 Overview of Spill Risk Analysis ...........................................3-120

3.2.1.4.2 Trajectory Modeling for Offshore Spills ≥1,000 bbl .............3-121

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

Probability of Occurrence....................................................3-123

3.2.1.4.4 Most Likely Source of Offshore Spills ≥1,000 bbl ...............3-125

3.2.1.4.5 Most Likely Size of an Offshore Spill ≥1,000 bbl.................3-125

3.2.1.4.6 Length of Coastline Affected by Offshore Spills 

≥1,000 bbl ............................................................................3-125

3.2.1.4.7 Risk Analysis by Resource..................................................3-126

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

Contacting Coastal and Offshore Areas..............................3-126

3.2.1.5 Analysis of Offshore Spills <1,000 bbl ...................................................3-127

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

Total Volume of Oil Spilled..................................................3-127

3.2.1.5.2 Most Likely Source and Type of Offshore Spills 

<1,000 bbl............................................................................3-127

3.2.1.5.3 Most Likely Size of Offshore Spills <1,000 bbl....................3-127

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

Contacting Coastal and Offshore Areas..............................3-127

3.2.1.6 Analysis of Coastal Spills.......................................................................3-128

3.2.1.6.1 Estimated Number and Most Likely Sizes of Coastal 

Spills ....................................................................................3-128

3.2.1.6.2 Likelihood of Coastal Spill Contact......................................3-128

3.2.2 Losses of Well Control...........................................................................................3-129

3.2.3 Accidental Air Emissions........................................................................................3-132

3.2.3.1 Hydrogen Sulfide and Sulfurous Petroleum...........................................3-132

3.2.4 Pipeline Failures.....................................................................................................3-134

3.2.5 Vessel and Helicopter Collisions ...........................................................................3-135
Table of Contents vii

3.2.6 Chemical and Drilling-Fluid Spills ..........................................................................3-137

3.2.7 Trash and Debris....................................................................................................3-138

3.2.8 Spill Response .......................................................................................................3-139

3.2.8.1 BSEE Spill-Response Requirements and Initiatives..............................3-139

3.2.8.1.1 Spill-Response Requirements.............................................3-139

3.2.8.1.2 Spill-Response Initiatives ....................................................3-141

3.2.8.2 Offshore Response, Containment, and Cleanup Technology ...............3-141

3.2.8.2.1 Mechanical Cleanup............................................................3-144

3.2.8.2.2 Spill Treating Agents ...........................................................3-147

3.2.8.2.3 In-situ Burning......................................................................3-150

3.2.8.2.4 Natural Dispersion...............................................................3-150

3.2.8.3 Onshore Response and Cleanup...........................................................3-151

3.3 Cumulative Impacts ............................................................................................................3-157

3.3.1 Cumulative OCS Oil and Gas Program Scenario..................................................3-157

3.3.1.1 Cumulative OCS Oil and Gas Program Projected Production...............3-159

3.3.1.2 Cumulative Geological and Geophysical Surveys .................................3-160

3.3.1.3 Cumulative Exploration and Delineation Plans and Drilling...................3-161

3.3.1.4 Cumulative Development and Production Drilling .................................3-161

3.3.1.5 Infrastructure Emplacement/Structure Installation and 

Decommissioning Activities....................................................................3-162

3.3.1.6 Infrastructure Presence..........................................................................3-163

3.3.1.7 Transport................................................................................................3-164

3.3.1.8 Discharges and Wastes .........................................................................3-165

3.3.1.9 Decommissioning and Removal Operations..........................................3-165

3.3.1.10 Coastal Infrastructure.............................................................................3-165

3.3.1.11 Air Emissions..........................................................................................3-165

3.3.2 Non-OCS Oil- and Gas-Related Impact-Producing Factors..................................3-166

3.3.2.1 State Oil and Gas Activity ......................................................................3-166

3.3.2.1.1 State Pipeline Infrastructure ................................................3-168

3.3.2.1.2 Artificial Reefs......................................................................3-168

3.3.2.2 Marine Vessel Activity ............................................................................3-169

3.3.2.3 Non-OCS Oil- and Gas-Related Wastes and Discharges .....................3-171

3.3.2.3.1 Potentially Polluting Shipwrecks..........................................3-171

3.3.2.3.2 Discharges Associated with Military Activities.....................3-172

3.3.2.3.3 Historical Chemical Weapon Disposal Areas......................3-173

3.3.2.3.4 Historical Industrial Waste Dumping Areas.........................3-174

3.3.2.3.5 Dredged Material Disposal..................................................3-174

3.3.2.3.6 Land-Based Discharges ......................................................3-177

3.3.2.3.7 Trash and Debris .................................................................3-177

3.3.2.4 Non-OCS Oil- and Gas-Related Spills...................................................3-178

3.3.2.5 Non-OCS Oil- and Gas- Related Air Emissions.....................................3-181

3.3.2.6 Other Non-OCS Oil- and Gas-Related Activities ...................................3-181

3.3.2.6.1 Military Warning and Water Test Areas ..............................3-181

3.3.2.6.2 Offshore Deepwater Ports and Nearshore Liquefied 

Natural Gas Terminals.........................................................3-182

3.3.2.6.3 Development of Gas Hydrates ............................................3-184

3.3.2.6.4 Renewable Energy and Alternative Use .............................3-185

3.3.2.6.5 Aquaculture..........................................................................3-187

3.3.2.6.6 OCS Sand Borrowing ..........................................................3-188

3.3.2.7 Noise from Non-OCS Oil- and Gas-Related Sources............................3-191
viii Gulf of Mexico Multisale EIS

3.3.2.8 Coastal Environments ............................................................................3-193

3.3.2.8.1 Sea-Level Rise and Subsidence .........................................3-193

3.3.2.8.2 Erosion.................................................................................3-196

3.3.2.8.3 Coastal Restoration Programs ............................................3-196

3.3.2.8.4 Saltwater Intrusion...............................................................3-203

3.3.2.8.5 Maintenance Dredging and Federal Channels....................3-204

3.3.2.9 Natural Events and Processes...............................................................3-206

3.3.2.9.1 Physical Oceanography.......................................................3-206

3.3.2.9.2 Natural Seeps ......................................................................3-207

3.3.2.9.3 Hurricanes ...........................................................................3-207

3.3.2.9.4 Climate Change...................................................................3-209

3.3.2.10 Mississippi River Hydromodification ......................................................3-209

3.3.2.11 Mississippi River Eutrophication ............................................................3-210

3.3.2.12 Hypoxia...................................................................................................3-211

3.3.2.13 Sedimentation.........................................................................................3-212
Table of Contents ix

Volume II 

Page

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

LIST OF TABLES...............................................................................................................................xxxi

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

4.0 Overview................................................................................................................................. 4-3

4.0.1 What Encompasses the Affected Environment for a Gulf of Mexico Lease Sale? ... 4-5

4.0.2 How are the Potential Environmental Consequences Determined? ......................... 4-6

4.0.2.1 Routine Activities........................................................................................ 4-9

4.0.2.2 Accidental Events....................................................................................... 4-9

4.0.2.3 Cumulative Impacts.................................................................................... 4-9

4.0.2.4 Incomplete or Unavailable Information .................................................... 4-10

4.0.2.5 Alternative A ............................................................................................. 4-11

4.0.2.6 Alternative B ............................................................................................. 4-11

4.0.2.7 Alternative C............................................................................................. 4-12

4.0.2.8 Alternative D............................................................................................. 4-12

4.0.2.9 Alternative E ............................................................................................. 4-12

4.1 Air Quality ............................................................................................................................. 4-13

4.1.1 Description of the Affected Environment ................................................................. 4-16

4.1.2 Environmental Consequences................................................................................. 4-24

4.1.2.1 Routine Activities...................................................................................... 4-27

4.1.2.2 Accidental Events..................................................................................... 4-30

4.1.2.3 Cumulative Impacts.................................................................................. 4-33

4.1.2.3.1 Impacts Assessment ............................................................. 4-38

4.1.2.4 Incomplete or Unavailable Information .................................................... 4-51

4.1.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) ............................................................................................... 4-52

4.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area....................................................................................... 4-52

4.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area....................................................................................... 4-53

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ................................................................. 4-53

4.1.2.9 Alternative E—No Action.......................................................................... 4-53

4.2 Water Quality........................................................................................................................ 4-53

4.2.1 Description of the Affected Environment ................................................................. 4-56

4.2.2 Environmental Consequences................................................................................. 4-58

4.2.2.1 Routine Activities...................................................................................... 4-58

4.2.2.2 Accidental Events..................................................................................... 4-63

4.2.2.3 Cumulative Impacts.................................................................................. 4-64

4.2.2.4 Incomplete or Unavailable Information .................................................... 4-67

4.2.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) ............................................................................................... 4-67
x Gulf of Mexico Multisale EIS

4.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area....................................................................................... 4-68

4.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area....................................................................................... 4-68

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ................................................................. 4-69

4.2.2.9 Alternative E—No Action.......................................................................... 4-69

4.3 Coastal Habitats ................................................................................................................... 4-69

4.3.1 Estuarine Systems (Wetlands and Seagrass/Submerged Vegetation)................... 4-69

4.3.1.1 Description of the Affected Environment.................................................. 4-71

4.3.1.1.1 Wetlands................................................................................ 4-71

4.3.1.1.2 Submerged Aquatic Vegetation............................................. 4-74

4.3.1.2 Environmental Consequences ................................................................. 4-76

4.3.1.2.1 Routine Activities ................................................................... 4-76

4.3.1.2.2 Accidental Events .................................................................. 4-79

4.3.1.2.3 Cumulative Impacts ............................................................... 4-84

4.3.1.2.4 Incomplete or Unavailable Information.................................. 4-93

4.3.1.2.5 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative) ............................................................ 4-94

4.3.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area ......................................... 4-95

4.3.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area........................... 4-95

4.3.1.2.8 Alternative D—Alternative D—Alternative A, B, or C, 

with the Option to Exclude Available Unleased Blocks 

Subject to the Topographic Features, Live Bottom 

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

Alabama, Stipulations............................................................ 4-96

4.3.1.2.9 Alternative E—No Action....................................................... 4-96

4.3.2 Coastal Barrier Beaches and Associated Dunes..................................................... 4-96

4.3.2.1 Description of the Affected Environment.................................................. 4-98

4.3.2.2 Environmental Consequences ...............................................................4-102

4.3.2.2.1 Routine Activities .................................................................4-102

4.3.2.2.2 Accidental Events ................................................................4-104

4.3.2.2.3 Cumulative Impacts .............................................................4-106

4.3.2.2.4 Incomplete or Unavailable Information................................4-112

4.3.2.2.5 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative) ..........................................................4-113

4.3.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area .......................................4-114

4.3.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-114
Table of Contents xi

4.3.2.2.8 Alternative D—Alternative D—Alternative A, B, or C, 

with the Option to Exclude Available Unleased Blocks 

Subject to the Topographic Features, Live Bottom 

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

Alabama, Stipulations..........................................................4-114

4.3.2.2.9 Alternative E—No Action.....................................................4-115

4.4 Deepwater Benthic Communities.......................................................................................4-115

4.4.1 Description of the Affected Environment ...............................................................4-121

4.4.1.1 Chemosynthetic Communities ...............................................................4-123

4.4.1.2 Deepwater Coral Communities ..............................................................4-127

4.4.2 Environmental Consequences...............................................................................4-129

4.4.2.1 Routine Activities....................................................................................4-129

4.4.2.2 Accidental Events...................................................................................4-133

4.4.2.3 Cumulative Impacts................................................................................4-137

4.4.2.4 Incomplete or Unavailable Information ..................................................4-140

4.4.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) .............................................................................................4-141

4.4.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.....................................................................................4-142

4.4.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.....................................................................................4-143

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ...............................................................4-144

4.4.2.9 Alternative E—No Action........................................................................4-144

4.5 Sargassum and Associated Communities .........................................................................4-145

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

4.5.2 Environmental Consequences...............................................................................4-152

4.5.2.1 Routine Activities....................................................................................4-153

4.5.2.2 Accidental Events...................................................................................4-154

4.5.2.3 Cumulative Impacts................................................................................4-156

4.5.2.4 Incomplete or Unavailable Information ..................................................4-159

4.5.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) .............................................................................................4-160

4.5.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.....................................................................................4-160

4.5.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.....................................................................................4-161

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ...............................................................4-161

4.5.2.9 Alternative E—No Action........................................................................4-161
xii Gulf of Mexico Multisale EIS

4.6 Live Bottom Habitats ..........................................................................................................4-161

4.6.1 Topographic Features and Associated Communities............................................4-163

4.6.1.1 Description of the Affected Environment................................................4-167

4.6.1.2 Environmental Consequences ...............................................................4-172

4.6.1.2.1 Routine Activities .................................................................4-172

4.6.1.2.2 Accidental Events ................................................................4-174

4.6.1.2.3 Cumulative Impacts .............................................................4-178

4.6.1.2.4 Incomplete or Unavailable Information................................4-180

4.6.1.2.5 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative) ..........................................................4-182

4.6.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area .......................................4-183

4.6.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-183

4.6.1.2.8 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-184

4.6.1.2.9 Alternative E—No Action.....................................................4-184

4.6.2 Pinnacles and Low-Relief Features and Associated Communities.......................4-185

4.6.2.1 Description of the Affected Environment................................................4-190

4.6.2.2 Environmental Consequences ...............................................................4-196

4.6.2.2.1 Routine Activities .................................................................4-196

4.6.2.2.2 Accidental Events ................................................................4-199

4.6.2.2.3 Cumulative Impacts .............................................................4-203

4.6.2.2.4 Incomplete or Unavailable Information................................4-207

4.6.2.2.5 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative) ..........................................................4-208

4.6.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area .......................................4-209

4.6.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-210

4.6.2.2.8 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-211

4.6.2.2.9 Alternative E—No Action.....................................................4-212

4.7 Fishes and Invertebrate Resources ...................................................................................4-213

4.7.1 Description of the Affected Environment ...............................................................4-216

4.7.2 Environmental Consequences...............................................................................4-221

4.7.2.1 Routine Activities....................................................................................4-221

4.7.2.2 Accidental Events...................................................................................4-226

4.7.2.3 Cumulative Impacts................................................................................4-227

4.7.2.4 Incomplete or Unavailable Information ..................................................4-231

4.7.2.5 Alternatives A, B, C, and D ....................................................................4-231

4.7.2.6 Alternative E—No Action........................................................................4-232
Table of Contents xiii

4.8 Birds....................................................................................................................................4-232

4.8.1 Description of the Affected Environment ...............................................................4-235

4.8.2 Environmental Consequences...............................................................................4-245

4.8.2.1 Routine Activities....................................................................................4-245

4.8.2.2 Accidental Events...................................................................................4-247

4.8.2.3 Cumulative Impacts................................................................................4-249

4.8.2.4 Incomplete or Unavailable Information ..................................................4-254

4.8.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) .............................................................................................4-254

4.8.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.....................................................................................4-256

4.8.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.....................................................................................4-257

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ...............................................................4-258

4.8.2.9 Alternative E—No Action........................................................................4-259

4.9 Protected Species ..............................................................................................................4-259

4.9.1 Marine Mammals....................................................................................................4-265

4.9.1.1 Description of the Affected Environment................................................4-266

4.9.1.2 Environmental Consequences ...............................................................4-278

4.9.1.2.1 Routine Activities .................................................................4-279

4.9.1.2.2 Accidental Events ................................................................4-289

4.9.1.2.3 Cumulative Impacts .............................................................4-297

4.9.1.2.4 Incomplete or Unavailable Information................................4-303

4.9.1.2.5 Alternatives A, B, C, and D..................................................4-306

4.9.1.2.6 Alternative E—No Action.....................................................4-308

4.9.2 Sea Turtles.............................................................................................................4-308

4.9.2.1 Description of the Affected Environment................................................4-308

4.9.2.2 Environmental Consequences ...............................................................4-318

4.9.2.2.1 Routine Activities .................................................................4-319

4.9.2.2.2 Accidental Events ................................................................4-324

4.9.2.2.3 Cumulative Impacts .............................................................4-329

4.9.2.2.4 Incomplete or Unavailable Information................................4-334

4.9.2.2.5 Alternatives A, B, C, and D..................................................4-335

4.9.2.2.6 Alternative E—No Action.....................................................4-336

4.9.3 Beach Mice (Alabama, Choctawhatchee, Perdido Key, and St. Andrew).............4-336

4.9.3.1 Description of the Affected Environment................................................4-337

4.9.3.2 Environmental Consequences ...............................................................4-337

4.9.3.2.1 Routine Activities .................................................................4-338

4.9.3.2.2 Accidental Events ................................................................4-338

4.9.3.2.3 Cumulative Impacts .............................................................4-339

4.9.3.2.4 Incomplete or Unavailable Information................................4-340

4.9.3.2.5 Alternative A—Regionwide OCS Proposed Lease Sale 

(The Preferred Alternative)..................................................4-340

4.9.3.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area .......................................4-341
xiv Gulf of Mexico Multisale EIS

4.9.3.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-341

4.9.3.2.8 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-342

4.9.3.2.9 Alternative E—No Action.....................................................4-342

4.9.4 Protected Birds.......................................................................................................4-342

4.9.4.1 Description of the Affected Environment................................................4-342

4.9.4.2 Environmental Consequences ...............................................................4-347

4.9.4.2.1 Routine Activities .................................................................4-348

4.9.4.2.2 Accidental Events ................................................................4-349

4.9.4.2.3 Cumulative Impacts .............................................................4-349

4.9.4.2.4 Incomplete or Unavailable Information................................4-350

4.9.4.2.5 Alternative A—Regionwide OCS Proposed Lease Sale 

(The Preferred Alternative)..................................................4-350

4.9.4.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area .......................................4-350

4.9.4.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-351

4.9.4.2.8 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-351

4.9.4.2.9 Alternative E—No Action.....................................................4-351

4.9.5 Protected Corals ....................................................................................................4-351

4.9.5.1 Description of the Affected Environment................................................4-351

4.9.5.2 Environmental Consequences ...............................................................4-353

4.9.5.2.1 Routine Activities .................................................................4-354

4.9.5.2.2 Accidental Events ................................................................4-354

4.9.5.2.3 Cumulative Impacts .............................................................4-354

4.9.5.2.4 Alternatives A, B, and C ......................................................4-355

4.9.5.2.5 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-356

4.9.5.2.6 Alternative E—No Action.....................................................4-356

4.10 Commercial Fisheries.........................................................................................................4-356

4.10.1 Description of the Affected Environment ...............................................................4-358

4.10.2 Environmental Consequences...............................................................................4-360

4.10.2.1 Routine Activities....................................................................................4-360

4.10.2.2 Accidental Events...................................................................................4-361

4.10.2.3 Cumulative Impacts................................................................................4-362

4.10.2.4 Incomplete or Unavailable Information ..................................................4-365

4.10.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) .............................................................................................4-365
Table of Contents xv 

4.10.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.....................................................................................4-365

4.10.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.....................................................................................4-366

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ...............................................................4-366

4.10.2.9 Alternative E—No Action........................................................................4-366

4.11 Recreational Fishing...........................................................................................................4-367

4.11.1 Description of the Affected Environment ...............................................................4-368

4.11.2 Environmental Consequences...............................................................................4-375

4.11.2.1 Routine Activities....................................................................................4-376

4.11.2.2 Accidental Events...................................................................................4-377

4.11.2.3 Cumulative Impacts................................................................................4-377

4.11.2.4 Incomplete or Unavailable Information ..................................................4-379

4.11.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) .............................................................................................4-379

4.11.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.....................................................................................4-380

4.11.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.....................................................................................4-380

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ...............................................................4-381

4.11.2.9 Alternative E—No Action........................................................................4-381

4.12 Recreational Resources .....................................................................................................4-381

4.12.1 Description of the Affected Environment ...............................................................4-383

4.12.2 Environmental Consequences...............................................................................4-387

4.12.2.1 Routine Activities....................................................................................4-387

4.12.2.2 Accidental Events...................................................................................4-391

4.12.2.3 Cumulative Impacts................................................................................4-393

4.12.2.4 Incomplete or Unavailable Information ..................................................4-397

4.12.2.5 Alternative A—Regionwide OCS Lease Sale (The Preferred 

Alternative) .............................................................................................4-397

4.12.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the Proposed 

Lease Sale Area.....................................................................................4-398

4.12.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding 

Available Unleased Blocks in the CPA/EPA Portions of the Proposed 

Lease Sale Area.....................................................................................4-398

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

Available Unleased Blocks Subject to the Topographic Features, 

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

County, Alabama, Stipulations ...............................................................4-399

4.12.2.9 Alternative E—No Action........................................................................4-399
xvi Gulf of Mexico Multisale EIS

4.13 Archaeological Resources..................................................................................................4-399

4.13.1 Description of the Affected Environment ...............................................................4-401

4.13.1.1 Prehistoric...............................................................................................4-401

4.13.1.2 Historic....................................................................................................4-403

4.13.2 Environmental Consequences...............................................................................4-406

4.13.2.1 Routine Activities....................................................................................4-406

4.13.2.2 Accidental Events...................................................................................4-408

4.13.2.3 Cumulative Impacts................................................................................4-410

4.13.2.4 Incomplete or Unavailable Information ..................................................4-413

4.13.2.5 Alternatives A, B, C, and D ....................................................................4-414

4.13.2.6 Alternative E—No Action........................................................................4-415

4.14 Human Resources and Land Use ......................................................................................4-415

4.14.1 Land Use and Coastal Infrastructure.....................................................................4-415

4.14.1.1 Description of the Affected Environment................................................4-418

4.14.1.1.1 Land Use .............................................................................4-418

4.14.1.1.2 Coastal Infrastructure ..........................................................4-422

4.14.1.2 Environmental Consequences ...............................................................4-424

4.14.1.2.1 Routine Activities .................................................................4-424

4.14.1.2.2 Accidental Events ................................................................4-426

4.14.1.2.3 Cumulative Impacts .............................................................4-429

4.14.1.2.4 Incomplete or Unavailable Information................................4-436

4.14.1.2.5 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative) ..........................................................4-437

4.14.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area .......................................4-438

4.14.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-438

4.14.1.2.8 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-439

4.14.1.2.9 Alternative E—No Action.....................................................4-439

4.14.2 Economic Factors ..................................................................................................4-439

4.14.2.1 Description of the Affected Environment................................................4-440

4.14.2.2 Environmental Consequences ...............................................................4-443

4.14.2.2.1 Routine Activities .................................................................4-444

4.14.2.2.2 Accidental Events ................................................................4-446

4.14.2.2.3 Cumulative Impacts .............................................................4-447

4.14.2.2.4 Incomplete or Unavailable Information................................4-453

4.14.2.2.5 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative) ..........................................................4-454

4.14.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the WPA Portion 

of the Proposed Lease Sale Area .......................................4-457

4.14.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-461
Table of Contents xvii

4.14.2.2.8 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-464

4.14.2.2.9 Alternative E—No Action.....................................................4-464

4.14.3 Social Factors (Including Environmental Justice)..................................................4-465

4.14.3.1 Description of the Affected Environment................................................4-466

4.14.3.2 Environmental Consequences ...............................................................4-471

4.14.3.2.1 Routine Activities .................................................................4-472

4.14.3.2.2 Accidental Events ................................................................4-473

4.14.3.2.3 Cumulative Impacts .............................................................4-474

4.14.3.2.4 Incomplete or Unavailable Information................................4-482

4.14.3.2.5 Alternative A—Regionwide OCS Lease Sale (The 

Preferred Alternative) ..........................................................4-483

4.14.3.2.6 Alternative B—Regionwide OCS Lease Sale Excluding 

Available Unleased Blocks in the WPA Portion of the 

Proposed Lease Sale Area .................................................4-484

4.14.3.2.7 Alternative C—Regionwide OCS Proposed Lease Sale 

Excluding Available Unleased Blocks in the CPA/EPA 

Portions of the Proposed Lease Sale Area.........................4-484

4.14.3.2.8 Alternative D—Alternative A, B, or C, with the Option 

to Exclude Available Unleased Blocks Subject to the 

Topographic Features, Live Bottom (Pinnacle Trend), 

and/or Blocks South of Baldwin County, Alabama, 

Stipulations ..........................................................................4-484

4.14.3.2.9 Alternative E—No Action.....................................................4-484

4.14.3.3 Environmental Justice Determination ....................................................4-485

4.15 Unavoidable Adverse Impacts of a Proposed Action.........................................................4-486

4.16 Irreversible and Irretrievable Commitment of Resources...................................................4-489

4.16.1 Coastal Habitats.....................................................................................................4-490

4.16.2 Biological Resources..............................................................................................4-490

4.16.2.1 Threatened and Endangered Species ...................................................4-490

4.16.2.2 Fish and Invertebrate Resources, Deepwater Benthic Communities, 

Commercial Fisheries, and Recreational Fishing ..................................4-490

4.16.3 Archaeological Resources .....................................................................................4-491

4.16.4 Oil and Gas Development......................................................................................4-491

4.16.5 Loss of Human and Animal Life.............................................................................4-491

4.17 Relationship Between the Short-term Use of Man’s Environment and the Maintenance 

and Enhancement of Long-term Productivity.....................................................................4-491

4.17.1 Short-Term Use......................................................................................................4-491

4.17.2 Relationship to Long-Term Productivity.................................................................4-493

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

5.0 Introduction............................................................................................................................. 5-3

5.1 Coastal Zone Management Act.............................................................................................. 5-3

5.2 Endangered Species Act........................................................................................................ 5-4

5.3 Magnuson-Stevens Fishery Conservation and Management Act.......................................... 5-5

5.4 National Historic Preservation Act.......................................................................................... 5-5

5.5 Government-to-Government Tribal Consultation................................................................... 5-7
xviii Gulf of Mexico Multisale EIS

5.6 National Environmental Policy Act ......................................................................................... 5-8

5.6.1 Development of the Proposed Actions ...................................................................... 5-8

5.6.1.1 Notice of Intent to Prepare an EIS and Call for Information ...................... 5-8

5.6.1.2 Summary of Comments Received in Response to the Call 

for Information ............................................................................................ 5-9

5.6.1.3 Area ID Memorandum................................................................................ 5-9

5.6.2 Development of the Draft Multisale EIS................................................................... 5-10

5.6.2.1 Scoping..................................................................................................... 5-10

5.6.2.2 Summary of Scoping Comments ............................................................. 5-12

5.6.2.3 Additional Public Input Opportunities ....................................................... 5-15

5.6.2.4 Cooperating Agencies.............................................................................. 5-15

5.6.2.5 Distribution of the Draft Multisale EIS for Review and Comment ............ 5-16

5.6.3 Development of the Final Multisale EIS................................................................... 5-20

5.6.3.1 Major Differences Between the Draft and Final Multisale EISs ............... 5-20

5.6.3.2 Public Meetings ........................................................................................ 5-20

5.6.3.3 Comments Received on the Draft Multisale EIS and BOEM’s 

Responses................................................................................................ 5-21

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

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

8 GLOSSARY .................................................................................................................................... 8-3
Table of Contents xix 

Volume III 

Page 

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

LIST OF TABLES ............................................................................................................................ xxxi

APPENDICES 

Appendix A Postlease Permitting and Approval Processes ...................................................... A-3

Appendix B Commonly Applied Mitigating Measures ............................................................... B-3

Appendix C Cooperating Agency Memorandum of Agreement ................................................ C-3

Appendix D Proposed lease Mitigating Measures (Stipulations) .............................................. D-3

Appendix E Oil Spill Risk Analysis Figures ............................................................................... E-3

Appendix F Air Quality: WRF Model Performance ................................................................... F-1

Appendix G Air Quality: Emissions for the Cumulative and Visibility Impacts .......................... G-1 

Appendix H Air Quality: Cumulative and Visibility Impacts ...................................................... H-1

Appendix I Species Not Considered Further ............................................................................. I-3

Appendix J State Coastal Management Programs ................................................................... J-3

Appendix K Consultation Correspondence ............................................................................... K-3

Appendix L Responses to Public Comments on the Draft Multisale EIS ................................... L-3

KEYWORD INDEX ............................................................................................................. Keywords-3

List of Figures xxi

LIST OF FIGURES

Page

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

Eastern Planning Areas. ............................................................................................... 1-4 

Figure 1-2. Energy Use in the United States................................................................................... 1-6 

Figure 1-3. OCS Oil and Gas Program Development Process....................................................... 1-7 

Figure 1-4. Planning for the Five-Year Program. ............................................................................ 1-9 

Figure 1-5. Typical Planning Timeline for Regional OCS Oil and Gas Lease Sales. ................... 1-10

Figure 1-6. Supplemental Approach Showing the Tiering Relationships for Proposed Gulf 

of Mexico Lease Sales................................................................................................ 1-12 

Figure 1-7. BOEM’s Consultation Partners for Specific Federal Statutes and Regulations. ........ 1-14 

Figure 1-8. BOEM’s Integrated Approach for Incorporating Applied Science into 

Decisionmaking........................................................................................................... 1-16 

Figure 2-1. Proposed Regionwide Lease Sale Area, Encompassing the Available Unleased 

Blocks within All Three Planning Areas (a total of approximately 91.93 million ac 

with approximately 75.4 million ac available for lease as of January 2017)................. 2-7 

Figure 2-2. Proposed Lease Sale Area for Alternative B, Excluding the Available Unleased 

Blocks in the WPA (approximately 63.35 million ac with approximately 

49.6 million ac available for lease as of January 2017)................................................ 2-9 

Figure 2-3. Proposed Lease Sale Area for Alternative C, Excluding the Available Unleased 

Blocks in the CPA and EPA (approximately 28.58 million ac with approximately 

25.8 million ac available for lease as of January 2017).............................................. 2-10

Figure 2-4. Identified Topographic Features, Pinnacle Trend, and Blocks South of Baldwin 

County, Alabama, Stipulation Blocks in the Gulf of Mexico........................................ 2-11 

Figure 2-5. Example of Excluded Blocks under Alternative D. ..................................................... 2-12 

Figure 2-6. Federal OCS Blocks Subject to the Gulf Islands National Seashore’s Information 

to Lessees and Operators........................................................................................... 2-17 

Figure 2-7. Historical Structure Locations near Horn and Petit Bois Islands................................ 2-18 

Figure 2-8. Military Warning Areas and Eglin Water Test Areas in the Gulf of Mexico. ............... 2-26 

Figure 3-1. Total Oil and Gas Production (BOE) in the Gulf of Mexico in the Low and High 

Production Scenario by Water Depth for a Single Proposed Lease Sale 

(2017-2066)................................................................................................................... 3-7 

Figure 3-2. Offshore Subareas in the Gulf of Mexico...................................................................... 3-8 

Figure 3-3. Typical Timeline for Offshore Oil and Gas Drilling...................................................... 3-11

Figure 3-4. General Well Schematic.............................................................................................. 3-19

Figure 3-5. (A) Number of Exploration and Delineation Wells Drilled over the Course 

of a Proposed Action under Alternative A for 50 Years. (B, C) Location 

of Exploration Wells Drilled during the Entire 50-Year Period.................................... 3-21

Figure 3-6. (A) Number of Production Wells Drilled over the Course of a Proposed Action 

under Alternative A for 50 Years. (B, C) Total Number of Development and 

Production Wells Drilled in the Low and High Production Scenario by Water 

Depth for Alternative A................................................................................................ 3-27

Figure 3-7. Offshore Production Systems. .................................................................................... 3-29

Figure 3-8. Number of Production Structures and Service Vessels Operating over the 

Course of a Proposed Action under Alternative A for 50 Years. (B, C) Total 

Number of Platforms Installed in the Low and High Production Scenario by 

Water Depth. ............................................................................................................... 3-36

Figure 3-9. Gulfwide OCS Oil- and Gas-Related Service Bases and Major Waterways.............. 3-49

Figure 3-10. Boundaries for USEPA Regions 4 and 6. ................................................................... 3-59

Figure 3-11. Onshore Infrastructure. ............................................................................................... 3-83

Figure 3-12. OCS-Related Ports and Waterways in the Gulf of Mexico. ........................................ 3-87
xxii Gulf of Mexico Multisale EIS

Figure 3-13. Number of Oil Spills ≥1 bbl That Have Occurred in the Gulf of Mexico for the 

Period 2001 through 2015.........................................................................................3-102

Figure 3-14. Total Volume (bbl) of Oil Spilled in Gulf of Mexico Waters for Spills ≥1 bbl 

for the Period 2001 through 2015 .............................................................................3-103

Figure 3-15. Number of Platform and Pipeline-Related Oil Spills ≥1 bbl That Have Occurred 

in the Gulf of Mexico for the Period 2001 through 2015...........................................3-104

Figure 3-16. Total Volume of Spilled Oil for Platform and Pipeline-Related Oil Spills ≥1 bbl 

That Have Occurred in the Gulf of Mexico for the Period 2001 through 2015. ........3-105

Figure 3-17. The Oil Spill Risk Analysis Model Process. ..............................................................3-121

Figure 3-18. OCS Oil and Gas Production Between 2004 and 2015............................................3-160

Figure 3-19. Number of Production Structures Installed and Decommissioned in Past 

Programs and the Range of Future Projections that May Occur as a Result 

of All Past, Present, and Future Actions ...................................................................3-162

Figure 3-20. 2015 Gulf of Mexico Hypoxic Zone...........................................................................3-212

Figure 4-1. Gulf of Mexico Region with the Planning Areas, Nonattainment Areas, Air 

Quality Jurisdiction, and Class I and Sensitive Class II Areas. .................................. 4-15

Figure 4-2. Year 2011 Gulfwide Emission Inventory Results for Total Platform and 

Non-Platform Criteria Pollutant Emissions (TPY)....................................................... 4-22

Figure 4-3. Year 2011 Gulfwide Emission Inventory Results for Total Platform and 

Non-Platform Greenhouse Gas Emissions (TPY). ..................................................... 4-22

Figure 4-4. 2011 Criteria Pollutant Emissions (TPY) from Platform Sources............................... 4-23

Figure 4-5. 2011 Greenhouse Gases (TPY) from Platform Sources............................................ 4-23

Figure 4-6. Overview of the Gulf of Mexico Region’s Cumulative and Visibility Impacts 

Assessment................................................................................................................. 4-35

Figure 4-7. Geographic Domain of the “Air Quality Modeling in the Gulf of Mexico” Region 

Study. .......................................................................................................................... 4-36

Figure 4-8. Coastal Watersheds of the Upper Gulf of Mexico Showing the Magnitude 

of Saltwater (intertidal) Wetland Loss to Open Water, 2004 to 2009 ......................... 4-72

Figure 4-9. Seagrass Locations of the Northern Gulf of Mexico. .................................................. 4-75

Figure 4-10. Deepwater Coral Records from NOAA’s National Deep-Sea Coral and Sponge 

Database ...................................................................................................................4-116

Figure 4-11. Estimated Distribution of Known Deepwater Benthic Communities in the 

Gulf of Mexico as of 2015. ........................................................................................4-124

Figure 4-12. BOEM’s Water Bottom Seismic Anomaly Database Showing Grouped Anomaly 

Categories Thought Likely to Support Deepwater Benthic Communities and 

Those That Generally Do Not ...................................................................................4-125

Figure 4-13. Example of a Predictive Habitat Suitability Model for Selected Deepwater, 

Framework-Forming Scleractinian Corals ................................................................4-129

Figure 4-14. Sargassum Loop System..........................................................................................4-148

Figure 4-15. Pelagic Brown Algae in the Genus Sargassum........................................................4-149

Figure 4-16. Small Fishes in Sargassum.......................................................................................4-150

Figure 4-17. Lease Blocks Subject to the Topographic Features and Live Bottom (Pinnacle 

Trend) Stipulations....................................................................................................4-162

Figure 4-18. Ecological Representation of Common Features on Topographic Features 

in the Gulf of Mexico. ................................................................................................4-168

Figure 4-19. General Location of the Pinnacle Trend (A), Multibeam Bathymetry and Named 

Reef Areas (B), and an Exaggerated Vertical Relief Profile of Rough Tongue 

Reef (C). ..................................................................................................................4-193

Figure 4-20. Migration Routes for Trans-Gulf Migratory Birds in the Presence of an Eastern 

Continental High........................................................................................................4-239

Figure 4-21. Migration Routes for Trans-Gulf Migratory Birds in the Presence of a Bermuda 

High ...........................................................................................................................4-240

Figure 4-22. Spring Wood Thrush Partial Migratory Corridor in North America ...........................4-241
List of Figures xxiii

Figure 4-23. Fall Wood Thrush Partial Migratory Corridor in North America................................4-242

Figure 4-24. Platform Density and Spring Migration Routes for Trans-Gulf Migratory Birds........4-243

Figure 4-25. Gulf of Mexico Protected Species’ Critical Habitats. ................................................4-261

Figure 4-26. Gulf Islands National Seashore. ...............................................................................4-387

Figure 4-27. Photograph of Remaining OCS Structures taken from Petit Bois Island Looking 

South (Petit Bois Island is within the Gulf Islands National Seashore 

and is a National Park Service-designated wilderness area.)..................................4-389

Figure 4-28. Economic Land Use Patterns. ..................................................................................4-419

Figure 4-29. Historical Land Loss in Louisiana, 1932-2010..........................................................4-435

Figure 4-30. Moderate Scenario: Projected Land Loss in Louisiana. ..........................................4-435

Figure 4-31. Less Optimistic Scenario: Projected Land Loss in Louisiana..................................4-436

Figure 4-32. Population of BOEM’s Economic Impact Areas in the Gulf of Mexico. ....................4-467

Figure 4-33. Percentage of Poverty in Texas and Louisiana. .......................................................4-469

Figure 4-34. Percentage of Poverty in Mississippi, Alabama, and Florida. ..................................4-469

Figure 4-35. Percentage of Minority Populations in Texas and Louisiana....................................4-470

Figure 4-36. Percentage of Minority Populations in Mississippi, Alabama, and Florida...............4-471

Figure 5-1. Timeline for the Development of the Multisale EIS....................................................... 5-8 

Figure E-1. The Oil Spill Risk Analysis Domain.............................................................................. E-4 

Figure E-2. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

the Shoreline (counties and parishes) as a Result of Alternative A. ........................... E-4 

Figure E-3. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

the Shoreline (counties and parishes) as a Result of Alternative A. ........................... E-5 

Figure E-4. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

the Shoreline (counties and parishes) as a Result of Alternative B. ........................... E-5 

Figure E-5. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

the Shoreline (counties and parishes) as a Result of Alternative B. ........................... E-6 

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

the Shoreline (counties and parishes) as a Result of Alternative C. ........................... E-6 

Figure E-7. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

the Shoreline (counties and parishes) as a Result of Alternative C. ........................... E-7 

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

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative A............................................................................................................ E-7 

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

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative A............................................................................................................ E-8 

Figure E-10. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative A............................................................................................................ E-8 

Figure E-11. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative A............................................................................................................ E-9 

Figure E-12. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative B............................................................................................................ E-9 
xxiv Gulf of Mexico Multisale EIS

Figure E-13. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative B.......................................................................................................... E-10

Figure E-14. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative B.......................................................................................................... E-10

Figure E-15. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative B.......................................................................................................... E-11

Figure E-16. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative C.......................................................................................................... E-11

Figure E-17. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative C.......................................................................................................... E-12

Figure E-18. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the Low Case in Resource Estimates 

for Alternative C.......................................................................................................... E-12

Figure E-19. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 30 Days 

Nearshore (“N”, 0-20 m), Shelf (“S”, 20-300 m), and Deepwater (“D”, 300 m to 

outer jurisdiction) Polygons as a Result of the High Case in Resource Estimates 

for Alternative C.......................................................................................................... E-13

Figure E-20. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

and 30 Days State Offshore Waters as a Result of Alternative A, B, or C................ E-13

Figure F-1. Location of the “Air Quality Modeling in the Gulf of Mexico Region” Study 

with Class I Areas and Platform Locations .................................................................. F-3 

Figure F-2. Ozone Nonattainment Areas in the Southeastern U.S................................................ F-4 

Figure F-3. Overview of the “Air Quality Modeling in the Gulf of Mexico Region” Study Tasks .... F-6 

Figure F-4. WRF 36-km CONUS (d01), 12-km SE Regional (d02), and 4-km Gulf of Mexico 

Region (d03) Domains. ................................................................................................ F-9 

Figure F-5. BOEM Gulf of Mexico OCS Region WRF 36-km METSTAT Wind Direction 

Performance for 2012. ............................................................................................... F-18

Figure F-6. BOEM Gulf of Mexico OCS Region WRF 36-km METSTAT Wind Speed 

Performance for 2012. ............................................................................................... F-18

Figure F-7. BOEM Gulfof Mexico OCS Region WRF 36-km METSTAT Temperature 

Performance for 2012. ............................................................................................... F-19

Figure F-8. BOEM Gulf of Mexico OCS Region WRF 36-km METSTAT Humidity 

Performance for 2012. ............................................................................................... F-19

Figure F-9. BOEM Gulf of Mexico OCS Region WRF 12-km METSTAT Wind Direction 

Performance for 2012. ............................................................................................... F-20

Figure F-10. BOEM Gulf of Mexico OCS Region WRF 12-km METSTAT Wind Speed 

Performance for 2012. ............................................................................................... F-20

Figure F-11. BOEM Gulf of Mexico OCS Region WRF 12-km METSTAT Temperature 

Performance for 2012. ............................................................................................... F-21

Figure F-12. BOEM Gulf of Mexico OCS Region WRF 12-km METSTAT Humidity 

Performance for 2012. ............................................................................................... F-21
List of Figures xxv 

Figure F-13. BOEM Gulf of Mexico OCS Region WRF 4-km METSTAT Wind Direction 

Performance for 2012. ............................................................................................... F-22

Figure F-14. BOEM Gulf of Mexico OCS Region WRF 4-km METSTAT Wind Speed 

Performance for 2012. ............................................................................................... F-22

Figure F-15. BOEM Gulf of Mexico OCS Region WRF 4-km METSTAT Temperature 

Performance for 2012. ............................................................................................... F-23

Figure F-16. BOEM Gulf of Mexico OCS Region WRF 4-km METSTAT Humidity 

Performance for 2012. ............................................................................................... F-23

Figure F-17. Wind Rose Locations for Port Isabel, TX (PTIT), Calcasieu, LA (CAPL), 

Gulfport, MS (KGPT), and Naples, FL (NPSF).......................................................... F-24

Figure F-18. 2012 WRF Wind Rose (left) Compared to 2012 Observation Wind Rose 

from Gulfport, MS (right) in 4-km Domain.................................................................. F-25

Figure F-19. 2012 WRF Wind Rose (left) Compared to 2012 Observation Wind Rose 

from Naples, FL (right) in 4-km Domain..................................................................... F-26

Figure F-20. 2012 WRF Wind Rose (left) Compared to 2012 Observation Wind Rose 

from Port Isabel, TX (right) in 4-km Domain.............................................................. F-27

Figure F-21. 2012 WRF Wind Rose (left) Compared to 2012 Observation Wind Rose 

from Calcasieu, LA (right) in 4-km Domain................................................................ F-28

Figure F-22. Vertical Profile Soundings Comparing the 4-km WRF (blue lines) to Upper-Air 

Observations Data (red lines) for Brownsville, TX on August 3, 2012, and 

Key West, FL on January 4, 2012, at 00 UTC........................................................... F-30

Figure F-23. January 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain............... F-33

Figure F-24. February 2012 PRISM Precipitation and WRF Precipitation 4-km Domain.............. F-34

Figure F-25. March 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain.................. F-35

Figure F-26. April 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain. ................... F-36

Figure F-27. May 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain..................... F-37

Figure F-28. June 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain.................... F-38

Figure F-29. July 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain. ................... F-39

Figure F-30. August 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain. ............... F-40

Figure F-31. September 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain......... F-41

Figure F-32. October 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain............... F-42

Figure F-33. November 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain........... F-43

Figure F-34. December 2012 PRISM Precipitation and WRF Precipitation, 4-km Domain........... F-44

Figure F-35. January 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-46

Figure F-36. February 2012 TRMM Precipitation Average and Corresponding WRF 

Precipitation Average in the 12-km Domain. ............................................................. F-47

Figure F-37. March 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-48

Figure F-38. April 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-49

Figure F-39. May 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-50

Figure F-40. June 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-51

Figure F-41. July 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-52

Figure F-42. August 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-53

Figure F-43. September 2012 TRMM Precipitation Average and Corresponding WRF 

Precipitation Average in the 12-km Domain. ............................................................. F-54

Figure F-44. October 2012 TRMM Precipitation Average and Corresponding WRF Precipitation 

Average in the 12-km Domain. .................................................................................. F-55
xxvi Gulf of Mexico Multisale EIS

Figure F-45. November 2012 TRMM Precipitation Average and Corresponding WRF 

Precipitation Average in the 12-km Domain. ............................................................. F-56

Figure F-46. December 2012 TRMM Precipitation Average and Corresponding WRF 

Precipitation Average in the 12-km Domain. ............................................................. F-57

Figure F-47. Daily Precipitation Plots from WRF, PRISM, and TRMM on August 30, 2012.......... F-59

Figure F-48. Daily Precipitation Plots from WRF, PRISM, and TRMM Databases 

on June 25, 2012........................................................................................................ F-60

Figure G-1. Location of the “Air Quality Modeling in the Gulf of Mexico Region” Study, 

with Class I Areas and Platform Locations .................................................................. G-1 

Figure G-2. Ozone Nonattainment Areas in the Southeastern U.S................................................ G-2 

Figure G-3. Overview of the “Air Quality Modeling in the Gulf of Mexico Region” Study Tasks .... G-4 

Figure G-4. WRF 36-km CONUS (d01), 12-km SE Regional (d02), and 4-km Gulf of Mexico 

Region (d03) Domains Along With the PGM Grids. .................................................... G-6 

Figure G-5. 2012 Platform NOx Emissions Aggregated by Lease Block ...................................... G-11

Figure G-6. 2012 Platform VOC Emissions Aggregated by Lease Block..................................... G-12

Figure G-7. 2012 Platform PM2.5 Emissions Aggregated by Lease Block.................................... G-13

Figure G-8. 2012 Non-platform NOx Emissions ............................................................................ G-15

Figure G-9. 2012 Non-platform VOC Emissions........................................................................... G-16

Figure G-10. 2012 Non-platform PM2.5 Emissions.......................................................................... G-17

Figure G-11. Emission Estimates for all Planning Areas and Future Activities. ............................. G-27

Figure G-12. Combined Annual NOx Emissions. ............................................................................ G-27

Figure G-13. Combined Annual VOC Emissions............................................................................ G-28

Figure G-14. Combined Annual PM2.5 Emissions........................................................................... G-28

Figure G-15. BOEM OCS Planning Areas and Water Depths........................................................ G-29

Figure H-1. Location of the “Air Quality Modeling in the Gulf of Mexico Region” Study, 

with Class I Areas......................................................................................................... H-1 

Figure H-2. Ozone Nonattainment Areas in the Southeastern U.S................................................ H-3 

Figure H-3. Class I and Sensitive Class II Areas in the Study Region. .......................................... H-5 

Figure H-4. Overview of the “Air Quality Modeling in the Gulf of Mexico Region” Study Tasks .... H-6 

Figure H-5. Meteorological (WRF model) and PGM Modeling Domains Including the 36-km 

Horizontal Grid Resolution CONUS WRF Domain, 12-km Resolution Southeast 

Regional WRF and PGM Domains (d02), and 4-km Resolution Gulf of Mexico 

OCS Region WRF and PGM Domains (d03)............................................................... H-7 

Figure H-6. BOEM’s 12-km 2012 Base Case NOx Emissions Summary in Tons per Year 

by Source Category and State (Alabama, Florida, Louisiana, Mississippi, 

and Texas). ................................................................................................................ H-19

Figure H-7. BOEM 12-km 2012 Base Case VOC Emissions Summary in Tons per Year 

by Source Category and State (Alabama, Florida, Louisiana, Mississippi, 

and Texas). ................................................................................................................ H-20

Figure H-8. BOEM 12-km 2012 Base Case PM2.5 Emissions Summary in Tons per Year 

by Source Category and State (Alabama, Florida, Louisiana, Mississippi, 

and Texas). ................................................................................................................ H-21

Figure H-9. BOEM 12-km 2012 Base Case SO2 Emissions Summary in Tons per Year 

by Source Category and State (Alabama, Florida, Louisiana, Mississippi, 

and Texas). ................................................................................................................ H-22

Figure H-10. BOEM 12-km Future Year NOx Emissions Summary in Tons per Year by Source 

Category and State (Alabama, Florida, Louisiana, Mississippi, and Texas)............. H-23

Figure H-11. BOEM 12-km Future Year VOC Emissions Summary in Tons per Year by Source 

Category and State (Alabama, Florida, Louisiana, Mississippi, and Texas)............. H-24

Figure H-12. BOEM 12-km Future Year PM2.5 Emissions Summary in Tons per Year by Source 

Category and State (Alabama, Florida, Louisiana, Mississippi, and Texas)............. H-25

Figure H-13. BOEM 12-km Future Year SO2 Emissions Summary in Tons per Year by Source 

Category and State (Alabama, Florida, Louisiana, Mississippi, and Texas)............. H-26
List of Figures xxvii 

Figure H-14. Spatial Distribution of NOx, VOC, SO2, and PM2.5 Emissions (tons per year) 

from New OCS Oil and Gas Production Platforms under the Proposed Action........ H-29

Figure H-15. Spatial Distribution of Emissions (tons per year) of NOx, VOC, SO2, and PM2.5 

from BOEM’s OCS Additional Oil and Gas Support Vessels and Helicopters 

under the Proposed Action Scenario. ........................................................................ H-30

Figure H-16. Spatial Distribution of NOx, VOC, SO2, and PM2.5 Emissions (tons per year) 

from BOEM’s OCS Oil and Gas Platforms, Support Vessels, and Helicopters 

under the No Action Alternative in BOEM’s 4-km Domain. ....................................... H-31

Figure H-17. Spatial Distribution of NOx, VOC, SO2, and PM2.5 Emissions (tons per year) 

from All Other Marine Vessel Activity in the Gulf of Mexico under the Future Year 

Scenario in BOEM’s 4-km Domain. ........................................................................... H-32

Figure H-18. Spatial Distribution of NOx, VOC, SO2, and PM2.5 Emissions (tons per year) 

from Other Anthropogenic U.S. Sources for the Future Year Scenario within 

BOEM’s 4-km Domain................................................................................................ H-33

Figure H-19. Ozone Monitoring Sites Used in the Model Performance Evaluation: CASTNet 

Sites in the Southeastern U.S. and AQS Sites within the 4-km Modeling Domain .. H-42

Figure H-20. Speciated PM Monitoring Sites Used in the Model Performance Evaluation: 

CSN Network, IMPROVE Network, and SEARCH Network ..................................... H-44

Figure H-21. Monthly Normalized Mean Bias and Normalized Mean Error for Daily Maximum 

8-hour Average Ozone at AQS and CASTNet Monitoring Sites Located within 

the 4-km Modeling Domain and the 12-km Domain .................................................. H-50

Figure H-22. Fraction of Site-days during Each Month of 2012 with Observed Daily Maximum 

8-hour Ozone Exceeding 60, 65, or 70 ppb Over All Monitoring Sites in the 

4-km Domain.............................................................................................................. H-51

Figure H-23. Observed (blue) and Predicted Monthly Mean Daily Maximum 8-hour Average 

Ozone Over All Sites in the 4-km Modeling Domain. ................................................ H-52

Figure H-24. Scatter and Scatter Density Plots for Observed vs. Predicted Daily Maximum 

8-hour Ozone in Q2 and Q3 for All AQS Monitoring Sites in the 4-km Modeling 

Domain....................................................................................................................... H-53

Figure H-25. Normalized Mean Bias (NMB) for Daily Maximum 8-hour Ozone for Q2 (top) 

and Q3........................................................................................................................ H-54

Figure H-26. Time Series of Daily Maximum 8-hour Ozone at Monitoring Sites with Highest 

Design Values in Harris, Brazoria, and Galveston Counties, Texas, for Q2 

and Q3........................................................................................................................ H-56

Figure H-27. Time Series of Daily Maximum 8-hour Ozone at Monitoring Sites in the 

Baton Rouge Nonattainment Area: LSU and Carville for Q2 and Q3 ...................... H-56

Figure H-28. Time Series of Daily Maximum 8-hour Ozone at the ALC188 (AlabamaCoushatta, Texas) CASTNet Monitoring Site for Q2 and Q3 .................................... H-57

Figure H-29. PM Monitoring Sites in the Southeastern U.S. Domain............................................. H-59

Figure H-30. Soccer Plots of Total PM2.5 Mass Model Performance Across the IMPROVE, 

CSN SEARCH, and FRM Daily Monitoring Networks for Sites in the Southeastern 

U.S. Domain............................................................................................................... H-60

Figure H-31. Comparisons of Predicted with Observed Daily Average PM at CSN Network 

Sites in the Southeastern U.S. for Q2 and Q4 for Total PM2.5, Other PM2.5, 

and Sodium ................................................................................................................ H-61

Figure H-32. Comparisons of Observed vs. Predicted OC and EC (bottom) at SEARCH and 

CSN Network Sites in the Southeastern U.S............................................................. H-62

Figure H-33. Monthly Normalized Mean Bias and Normalized Mean Error for Hourly NO2 and 

Daily NOy at SEARCH Network Sites and AQS Sites in the 4-km Domain............... H-63

Figure H-34. Monthly Normalized Mean Bias and Normalized Mean Error for NO3 at SEARCH 

Network Monitoring Sites and AQS Sites and NO3 Deposition at NADP Sites 

in the Southeastern U.S............................................................................................. H-64
xxviii Gulf of Mexico Multisale EIS

Figure H-35. Monthly Normalized Mean Bias and Normalized Mean Error at Monitoring Sites 

in the 4-km Domain for SO2, SO4, and SO4 Deposition Measured at NADP Sites... H-66

Figure H-36. Annual Normalized Mean Bias for Hourly SO2 (based on 12-km resolution 

CAMx results)............................................................................................................. H-67

Figure H-37. Monthly Normalized Mean Bias and Normalized Mean Error for Daily Average 

NH4 at CSN and SEARCHNetwork Sites in the 4-km Modeling Domain. ................ H-68

Figure H-38. Monthly Normalized Mean Bias and Normalized Mean Error for Hourly CO 

at SEARCH Network Sites and AQS Sites ................................................................ H-69

Figure H-39. Class I and Sensitive Class II Areas for Which Incremental AQ/AQRV Impacts 

Were Calculated......................................................................................................... H-73

Figure H-40. Base Scenario Ozone Design Values (DVC), Future Year Ozone Design Values 

(DVF) and Their Differences (DVF – DVC) Calculated Using the MATS UAA 

Tool............................................................................................................................. H-87

Figure H-41. MATS UAA Future Year Ozone Design Values (DFV) Calculated After First 

Removing the Hourly Contributions from a Source Group and the Corresponding 

Contributions of the Source Group to DVF Calculated by Subtracting the DVFs 

Shown in the Left-hand Column from the “All Sources” DVF Shown in the Top 

Right-hand Corner of Figure H-40 ............................................................................. H-88

Figure H-42. Modeled 4th Highest MDA8 Ozone for the Base Year and Future Year Scenarios 

and Their Differences................................................................................................. H-89

Figure H-43. Contributions of Source Groups A, B, C, D, and E to Future Year All-sources 

4th Highest MDA8 ...................................................................................................... H-91

Figure H-44. Contributions from Source Group F (natural and non-US emission sources 

including boundary conditions) and Boundary Conditions Only, to Future Year 

All-sources 4th Highest MDA8. .................................................................................. H-92

Figure H-45. Current Year (DVC) and Future Year (DVF) Annual Average PM2.5 Design 

Values from the MATS Unmonitored Area Analysis and the Difference, 

DVF – DVC................................................................................................................. H-98

Figure H-46. Contributions of Source Groups A, B, C, D, and E to the Future Year All-sources 

Annual Average PM2.5 Concentration Based on the MATS Unmonitored Area 

Analysis ...................................................................................................................... H-99

Figure H-47. Modeled 8th Highest Daily Average PM2.5 Concentrations for the Base Year, 

Future Year, and the Future – Base Difference....................................................... H-101

Figure H-48. Contributions of Source Groups A, B, C, D, and E to the Future Year All-sources 

8th Highest Daily Average PM2.5 Concentration...................................................... H-102

Figure H-49. Contributions from Source Group F (natural and non-U.S. emission sources 

including boundary conditions) and Boundary Conditions Only to Future Year 

All-sources 8th Highest 24-hour PM2.5..................................................................... H-103

Figure H-50. Modeled Annual Average PM2.5 Concentrations for the Base Year, Future Year, 

and the Future – Base Difference............................................................................ H-104

Figure H-51. Contributions of Source Group A, B, C, D, and E to the Future Year All-sources 

Annual Average PM2.5 Concentration ...................................................................... H-105

Figure H-52. Contributions from Source Group F (natural and non-U.S. emission sources 

including boundary conditions) and Boundary Conditions Only to Future Year 

All-sources Annual Average PM2.5 ........................................................................... H-106

Figure H-53. Modeled 2nd Highest 24-hour Average PM10 Concentrations for the Base Year, 

Future Year, and the Future – Base Difference....................................................... H-107

Figure H-54. Contributions of Source Groups A, B, C, D, and E to the Future Year All-sources 

2nd Highest Daily Average PM10 Concentration...................................................... H-108

Figure H-55. Contributions from Source Group F (natural and non-U.S. emission sources 

including boundary conditions) and Boundary Conditions Only to Future Year 

All-sources 2nd Highest Daily Average PM10 Concentration.................................... H-109
List of Figures xxix

Figure H-56. Modeled 8th Highest 1-hour NO2 Concentrations for the Base Year, Future 

Year, and the Future – Base Difference .................................................................. H-110

Figure H-57. Contributions of Source Group A, B, C, D, and E to the Future Year All-sources 

8th Highest Daily Average NO2 Concentrations ...................................................... H-111

Figure H-58. Modeled Annual Average NO2 Concentrations for the Base Year, Future Year, 

and the Future – Base Difference............................................................................ H-112

Figure H-59. Contributions of Source Groups A, B, C, D, and E to the Future Year All-sources 

Annual Average NO2 Concentrations. ..................................................................... H-113

Figure H-60. Modeled 4th Highest Daily Maximum 1-hour SO2 Concentrations for the Base 

Year, Future Year, and the Future – Base Difference............................................. H-115

Figure H-61. Contributions of Source Group A, B, C, D, and E to the Future Year All-sources 

4th Highest Daily Maximum 1-hour SO2 Concentration .......................................... H-116

Figure H-62. Modeled Annual 2nd Highest Block 3-hour SO2 Concentrations for the Base 

Year, Future Year, and the Future – Base Difference............................................. H-117

Figure H-63. Contributions of Source Group A, B, C, D, and E to the Future Year All-sources 

2nd Highest 3-hour Block Average SO2 Concentration........................................... H-118

Figure H-64. Modeled Annual 2nd Highest Non-overlapping Running 8-hour Average CO 

Concentrations for the Base Year, Future Year, and the Future – Base Difference..... H119

Figure H-65. Modeled Annual 2nd Highest 1-hour Average CO Concentrations for the Base 

Year, Future Year, and the Future – Base Difference............................................. H-120

List of Tables xxxi 

LIST OF TABLES

Page

Table 2-1. Applicable Stipulations by Alternative .......................................................................... 2-29

Table 2-2. Alternative Comparison Matrix. .................................................................................... 2-36 

Table 3-1. Projected Oil and Gas in the Gulf of Mexico OCS. ........................................................ 3-7 

Table 3-2. Offshore Scenario Activities and Impact-Producing Factors Related to a Single 

Proposed Lease Sale for Alternative A, B, or C from 2017 through 2066. .................... 3-9 

Table 3-3. Estimated Exploration and Seismic Survey Activity Leading Up To and Following 

a Proposed Lease Sale in the Gulf of Mexico. ............................................................. 3-16

Table 3-4. Oil Transportation Scenario under Alternatives A, B, and C........................................ 3-37

Table 3-5. Existing Coastal Infrastructure Related to OCS Oil- and Gas-Related Activities 

in the Gulf of Mexico..................................................................................................... 3-38

Table 3-6. OCS Pipeline Landfalls Installed from 1996 to 2014. .................................................. 3-42

Table 3-7. Waterway Length, Depth, Traffic, and Number of Trips for 2012. ............................... 3-45

Table 3-8. Pollution-Related Incidents of Noncompliance (INCs) Issued Since 1986. ................. 3-61

Table 3-9. National Pollutant Discharge Elimination System Inspections from 1999 

through 2016................................................................................................................. 3-62

Table 3-10. Annual Volume of Produced Water Discharged by Depth (millions of bbl). ................ 3-68

Table 3-11. OCS Oil- and Gas-Related Service Bases................................................................... 3-86

Table 3-12. Spill Rates for Petroleum Spills ≥1,000 Barrels from OCS Platforms and Pipelines, 

1964 through 2010......................................................................................................3-106

Table 3-13. Historic Spill Source, Location, and Characteristics of a Maximum Spill for 

Coastal Waters (data extracted from USDHS, CG records, 2002-July 2015). ..........3-108

Table 3-14. Petroleum Spills ≥1,000 Barrels from United States OCS Platforms, 

1964-July 2016. ..........................................................................................................3-111

Table 3-15. Petroleum Spills ≥1,000 Barrels from United States OCS Pipelines, 

1964-July 2016. ..........................................................................................................3-113

Table 3-16. Properties and Persistence by Oil Component Group. ..............................................3-117

Table 3-17. Probability (percent chance) of a Particular Number of Offshore Spills 

≥1,000 Barrels Occurring as a Result of Either Facility or Pipeline Operations 

Related to Alternative A, B, or C.................................................................................3-122

Table 3-18. Mean Number and Sizes of Spills Estimated to Occur in OCS Offshore Waters 

from an Accident Related to Rig/Platform and Pipeline Activities Supporting Each 

Alternative Over a 50-Year Time Period. ...................................................................3-123

Table 3-19. Oil-Spill Occurrence Probability Estimates for Offshore Spills ≥1,000 Barrels 

Resulting from Each Alternative (2017-2066) and the Cumulative OCS Oil and 

Gas Program (2017-2086)..........................................................................................3-124

Table 3-20. Oil-Spill Occurrence Probability Estimates for Offshore Spills ≥10,000 Barrels 

Resulting from Each Alternative (2017-2066) and the Cumulative OCS Oil and 

Gas Program (2017-2086)..........................................................................................3-124

Table 3-21. Number and Volume of Chemical and Synthetic-Based Fluid Spills for 

10-49 Barrels and >50 Barrels in the Gulf of Mexico from 2007 through 2014. ........3-137

Table 3-22. Primary Cleanup Options Used during the Deepwater Horizon Response. ..............3-142

Table 3-23. Future Activity Projections Associated with the Cumulative OCS Oil and Gas 

Program (2017-2086), Including All Future Activities that are Projected to Occur 

from Past, Proposed, and Future Lease Sales. .........................................................3-158

Table 3-24. Cumulative G&G Surveying Activities Expected in the Gulf of Mexico 

(2017-2086). ...............................................................................................................3-161

Table 3-25. Future Oil Transportation Projections Associated with the Cumulative OCS Oil 

and Gas Program (2017-2086), Including All Future Transportation that is 

Projected to Occur from Past, Proposed, and Future Lease Sales...........................3-164
xxxii Gulf of Mexico Multisale EIS

Table 3-26. Number of Vessel Calls at U.S. Gulf Ports Between 2002 and 20111. .....................3-170

Table 3-27. Quantities of Dredged Materials Disposed of in Ocean Dredged-Material Disposal 

Sites Between 2004 and 2013....................................................................................3-176

Table 3-28. Average Annual Inputs of Petroleum Hydrocarbons to Coastal Waters of the 

Gulf of Mexico, 1990-1999. ........................................................................................3-179

Table 3-29. Average Annual Inputs of Petroleum Hydrocarbons to Offshore Waters of the 

Gulf of Mexico, 1990-1999. ........................................................................................3-180

Table 3-30. Projected OCS Sand Resource Needs for Planned Restoration Projects.................3-189

Table 3-31. Hurricane Landfalls in the Northern Gulf of Mexico from 1995 through 2016. ..........3-208

Table 3-32. Oil Spilled from Pipelines on the Federal OCS, 2002-2009.......................................3-209

Table 4-1. Air Quality Impact-Producing Factors That Are Reasonably Foreseeable. ................. 4-14

Table 4-2. National Ambient Air Quality Standards....................................................................... 4-17

Table 4-3. Nonattainment and Maintenance Areas in the Gulf of Mexico Region. ....................... 4-19

Table 4-4. Source Categories for Source Apportionment Calculations......................................... 4-37

Table 4-5. NAAQS and PSD Increments....................................................................................... 4-38

Table 4-6. Class I and Sensitive Class II Areas in Gulf Coast and Nearby States. ...................... 4-43

Table 4-7. Source Group for Incremental Impacts Analysis.......................................................... 4-45

Table 4-8. Water Quality Impact-Producing Factors That Are Reasonably Foreseeable............. 4-54

Table 4-9. Estuarine Systems Impact-Producing Factors That Are Reasonably Foreseeable..... 4-70

Table 4-10. Coastal Barrier Beaches and Associated Dunes Impact-Producing Factors That 

Are Reasonably Foreseeable....................................................................................... 4-97

Table 4-11. Deepwater Benthic Communities Impact-Producing Factors That are Reasonably 

Foreseeable................................................................................................................4-116

Table 4-12. Sargassum and Associated Communities Impact-Producing Factors That Are 

Reasonably Foreseeable............................................................................................4-145 

Table 4-13. Topographic Features Impact-Producing Factors That Are Reasonably 

Foreseeable................................................................................................................4-164

Table 4-14. Pinnacles and Low-Relief Features Impact-Producing Factors That Are 

Reasonably Foreseeable............................................................................................4-185

Table 4-15. Fish and Invertebrate Resources Impact-Producing Factors That Are Reasonably 

Foreseeable................................................................................................................4-215

Table 4-16. Birds Impact-Producing Factors That Are Reasonably Foreseeable.........................4-233

Table 4-17. Species within the Gulf of Mexico That Are Protected Under the Endangered 

Species Act and/or the Marine Mammal Protection Act.............................................4-260

Table 4-18. Protected Species Impact-Producing Factors That Are Reasonably Foreseeable. ..4-263

Table 4-19. Best Available Population Estimates for Marine Mammal Species in the Northern 

Gulf of Mexico.............................................................................................................4-267

Table 4-20. Commercial Fisheries Impact-Producing Factors That Are Reasonably 

Foreseeable................................................................................................................4-357

Table 4-21. Landings Revenues: Landings Revenue by Species and State. ..............................4-359

Table 4-22. Recreational Fishing Impact Producing Factors That Are Reasonably 

Foreseeable................................................................................................................4-367

Table 4-23. CPA and EPA Effort Data: Angler Trips in the Gulf of Mexico..................................4-369

Table 4-24. CPA and EPA Catch Data: Number of Fish Species Caught by Recreational 

Anglers from 2008 through 2013 in Louisiana, Mississippi, and Alabama 

Combined....................................................................................................................4-371

Table 4-25. CPA and EPA Catch Data: Fish Species Caught by Recreational Anglers 

from 2008 through 2013 in West Florida....................................................................4-372

Table 4-26. Texas Effort Data: Number of Angler Trips from 2011 through 2015. ......................4-373

Table 4-27. Texas Catch Data: Top Species Landed by Recreational Fishermen......................4-374

Table 4-28. Recreational Resources Impact-Producing Factors That Are Reasonably 

Foreseeable. ...............................................................................................................4-382
List of Tables xxxiii

Table 4-29. Recreational and Tourism Employment and Value-Added in BOEM's Economic 

Impact Areas in 2013. .................................................................................................4-383

Table 4-30. Archaeological Surveys and Resources Identified, 2009-2014. ................................4-404

Table 4-31. Land Use and Coastal Infrastructure Impact-Producing Factors That Are 

Reasonably Foreseeable............................................................................................4-417

Table 4-32. Comparison of the 1954 and 2015 Populations by State...........................................4-429

Table 4-33. Economic and Demographic Information for BOEM's Economic Impact Areas 

in 2015. .......................................................................................................................4-441

Table 4-34. Sales Volumes, Sales Values, and Revenues...........................................................4-443

Table 4-35. Cumulative Low: MAG-PLAN Industry Expenditure Impacts....................................4-449

Table 4-36. Cumulative High: MAG-PLAN Industry Expenditure Impacts. ..................................4-450

Table 4-37. Economic and Demographic Information for BOEM's Economic Impact Areas 

in 2050. .......................................................................................................................4-452

Table 4-38. Gulf of Mexico Single Low: MAG-PLAN Industry Expenditure Impacts....................4-454

Table 4-39. Gulf of Mexico Single High: MAG-PLAN Industry Expenditure Impacts...................4-456

Table 4-40. CPA/EPA Single Low: MAG-PLAN Industry Expenditure Impacts. ..........................4-458

Table 4-41. CPA/EPA Single High: MAG-PLAN Industry Expenditure Impacts. .........................4-460

Table 4-42. WPA Single Low: MAG-PLAN Industry Expenditure Impacts...................................4-462

Table 4-43. WPA Single High: MAG-PLAN Industry Expenditure Impacts..................................4-463

Table B-1. Commonly Applied or “Standard” Mitigating Measures. ............................................... B-5 

Table F-1. Nonattainment and Maintenance Areas in the Southeastern U.S. ............................... F-5 

Table F-2. BOEM’s Gulf of Mexico OCS Region WRF Domain Configuration. ............................. F-8 

Table F-3. BOEM Gulf of Mexico OCS Region WRF Dataset Model Levels. .............................. F-10

Table F-4. BOEM Gulf of Mexico OCS Region WRF Physics Options........................................ F-13

Table F-5. Meteorological Model Performance Benchmarks for Simple and Complex 

Conditions.................................................................................................................... F-14

Table G-1. Nonattainment and Maintenance Areas in the Southeastern U.S. ............................... G-3 

Table G-2. Gulf of Mexico Air Quality Modeling Study Source Categories..................................... G-7 

Table G-3. Base Case Offshore Oil and Gas Production Source Emissions Estimates 

for the GOM Western and Central/Eastern Planning Areas. ...................................... G-10

Table G-4. Future Year Production Platform Emission Factors.................................................... G-21

Table G-5. Summary of Vessel Characteristics. ........................................................................... G-23

Table G-6. Load Factors to be Used in the Future Year Projections............................................ G-24

Table G-7. Marine Vessel Emission Factors (g/kW-hr)................................................................. G-24

Table G-8. Emission Estimates for the Western, Central, and Eastern Planning Areas, 

All Depths, By Year and Pollutant. .............................................................................. G-25

Table H-1. Nonattainment and Maintenance Areas in the Southeastern U.S. ............................... H-4 

Table H-1. Gulf of Mexico OCS Region Air Quality Modeling Study Source Categories ............... H-9 

Table H-3. 2012 Fire Criteria Air Pollutant Emissions Summary by Fire Type for BOEM’s 

36-, 12-, and 4-km Domains........................................................................................ H-14

Table H-4. 2012 Base Case and Future Year Emissions Summary by State for BOEM’S 

12-km Domain (only Gulf Coast States: Alabama, Florida, Louisiana, Mississippi, 

and Texas)................................................................................................................... H-18

Table H-5. 2012 Base Case and Future Year Emissions Summary by Source Category 

for BOEM’s 4-km Domain............................................................................................ H-26

Table H-6. Changes in Emissions between the 2012 Base Case and Future Year Emissions 

(short tons per year) by Source Category for BOEM’s 4-km Domain......................... H-27

Table H-7. Source Categories for Source Apportionment Calculations........................................ H-34

Table H-8. Domain Grid Definitions for the WRF and CAMx/CMAQ Modeling. ........................... H-35

Table H-9. Vertical Layer Interface Definition for WRF Simulations and the Layer-collapsing 

Scheme for the CAMx/CMAQ Layers.......................................................................... H-36

Table H-10. CAMx Model Configuration.......................................................................................... H-39

Table H-11. Definitions of Model Performance Evaluation Statistical Metrics................................ H-45
xxxiv Gulf of Mexico Multisale EIS

Table H-12. Ozone and PM Model Performance Goals and Criteria.............................................. H-46

Table H-13. Model Performance Statistics at Different Observed Ozone Concentration 

Screening Thresholds Based on All Monitoring Sites in the 4-km Domain ................ H-55

Table H-14. NAAQS and PSD Increments...................................................................................... H-71

Table H-15. Source Group for Incremental Impacts Analysis......................................................... H-72

Table H-16. Class I and Sensitive Class II Areas in Gulf Coast and Nearby States. ..................... H-74

Table H-17. Current Year (DVC) and Future Year (DVF) Ozone Design Values at Ambient Air 

Monitoring Sites within the 4-km Modeling Domain from MATS................................. H-82

Table H-18. Ozone Current (DVC) and Future Year (DVF) Design Values and Reduction 

in DVF with Contributions from Individual Source Groups Removed. ........................ H-84

Table H-19. MATS Ozone Design Value Results for All Monitoring Sites Where Exclusion 

of Contributions from Source Group A or B is Sufficient to Reduce the Predicted 

Future Design Value (DVF) from Above the NAAQS to Below the NAAQS 

(all values in ppb)......................................................................................................... H-86

Table H-20. Current Year (DVC) and Future Year (DVF) 24-Hour PM2.5 Design Values 

for Monitoring Sites in the 4-km Modeling Domain from MATS.................................. H-93

Table H-21. 24-Hour PM2.5 Current (DVC) and Future Year (DVF) Design Values and 

Reduction in DVF with Contributions from Individual Source Groups Removed........ H-94

Table H-22. Current (DVC) and Projected Future (DVF) Annual Average PM2.5 Design Values 

for Monitoring Sites in the 4-km Modeling Domain ..................................................... H-95

Table H-23. Annual Average PM2.5 Future Year Design Values (DVF) and Change in DVF 

with Contributions from Individual Source Groups Removed ..................................... H-96

Table H-24. Maximum Source Group Contributions for PSD Pollutants at Class I and 

Sensitive Class II Areas in the 4-km Modeling Domain. ........................................... H-121

Table H-25. Source Group Contributions for PSD Pollutants at All Class I and Sensitive 

Class II Areas in the 4-km Modeling Domain............................................................ H-123

Table H-26. Incremental Visibility Impacts Relative to Natural Background Conditions 

from Source Group A................................................................................................. H-124

Table H-27. Incremental Visibility Impacts Relative to Natural Background Conditions 

from Source Group B................................................................................................. H-125

Table H-28. Cumulative Visibility Results for 20% Worst Visibility Days (W20%) at Class I 

Areas for Base (2012) Year (BY) and Future Year (FY) Scenarios with All 

Sources Included and with Contributions from Each Source Group Removed........ H-128

Table H-29. Differences in Cumulative Visibility Results for 20% Worst Visibility Days (W20%) 

at Class I Areas Between the Future Year (FY) and Base Year (BY) Scenarios 

and Contributions of Each Source Group to the Future Year Scenario Visibility...... H-130

Table H-30. Cumulative Visibility Results for 20% Best Visibility Days (B20%) at Class I 

Areas for Base (2012) Year (BY) and Future Year (FY) Scenarios with All 

Sources Included and with Contributions from Each Source Group Removed........ H-132

Table H-31. Differences in Cumulative Visibility Results for 20% Best Visibility Days (B20%) 

at Class I Areas Between the Future Year (FY) and Base Year (BY) Scenarios 

and Contributions of Each Source Group to the Future Year Scenario Visibility...... H-133

Table H-32. Deposition Analysis Threshold Values (kg/ha/yr) as Defined in the Federal Land 

Manager Guidance .................................................................................................... H-135

Table H-33. Incremental Deposition Impacts from Source Groups A and B at Class I and 

Sensitive Class II Areas in the 4-km Domain............................................................ H-135

Table H-34. Cumulative Nitrogen (N) and Sulfur (S) Deposition Impacts (kg/ha/yr) under 

the Base and Future Year Scenarios (shading indicates values exceeding 

the Critical Load threshold)........................................................................................ H-136

Table L-1. Public Comments and BOEM’s Response Matrix........................................................ L-14
CHAPTER 4 

DESCRIPTION OF THE ENVIRONMENT AND IMPACT ANALYSIS

Description of the Affected Environment and Impact Analysis 4-3

Chapter 4 describes the 

affected environment and 

potential environmental 

consequences of a single 

lease sale. This 

Multisale EIS tiers from 

and uses information 

contained in the FiveYear Program EIS

(USDOI, BOEM, 2016b).

Chapter 4 describes the 

affected environment and 

potential environmental 

consequences of a single 

proposed lease sale. 

This Multisale EIS tiers 

from and uses the 

information contained in 

the Five-Year Program 

EIS (USDOI, BOEM, 

2016b).

What’s in This Chapter?

• Chapter 4 describes the affected environment and potential environmental consequences 

of a single proposed lease sale.

• Resources analyzed are as follows:

– Air Quality

– Water Quality

– Coastal Habitats (Estuarine Systems, 

and Coastal Barrier Beaches and 

Associated Dunes) 

– Deepwater Benthic Communities

– Sargassum and Associated 

Communities

– Live Bottom Habitats (Topographic 

Features, and Pinnacles and 

Low-Relief Features)

– Fishes and Invertebrate Resources

– Birds

– Protected Species (Marine Mammals, 

Sea Turtles, Beach Mice, Protected 

Birds, and Protected Corals) 

– Commercial Fisheries

– Recreational Fishing

– Recreational Resources

– Archaeological Resources

– Socioeconomic Issues (Land Use and 

Coastal Infrastructure, Economic 

Factors, and Social Factors, Including 

Environmental Justice)

• Impact-producing factors and impact-level definitions are identified for each resource.

• The analyses of environmental consequences consider the potential impacts from routine 

activities, accidental events, and cumulative impacts; and incomplete or unavailable 

information.

• Other analyses in this chapter include the following:

– Unavoidable Adverse Impacts of a Proposed Action

– Irreversible and Irretrievable Commitment of Resources

– Relationship Between the Short-term Use of Man’s Environment and the Maintenance 

and Enhancement of Long-term Productivity

4 DESCRIPTION OF THE AFFECTED ENVIRONMENT AND IMPACT 

ANALYSIS

4.0 OVERVIEW

As discussed in Chapter 1.3, BOEM makes individual 

decisions on whether and how to proceed with each lease sale 

pursuant to the OCSLA’s staged leasing process. Therefore, the 

analysis presented here is for a single proposed lease sale. 

However, since this is a programmatic analysis, this Multisale EIS 

will be used to support all 10 lease sale decisions. Additional NEPA

reviews (e.g., a Determination of NEPA Adequacy, an EA or, if 

determined necessary, a Supplemental EIS) will be conducted prior 

to subsequent lease sale decisions. This chapter describes the 

affected environment and the potential impacts of routine activities, 

reasonably foreseeable accidental events, and cumulative impacts

caused by a proposed lease sale and the alternatives on these 

resources.

This chapter is organized by groups of resources. The chapter is divided into the physical 

factors (i.e., air and water quality), biological factors (i.e., habitat resources followed by the fauna 
4-4 Gulf of Mexico Multisale EIS

that are found in or utilize these habitats), and finally the social environment, including environmental 

justice, commercial fisheries, recreational resources, and land use. 

• Air Quality (Chapter 4.1) 

• Water Quality (Chapter 4.2) 

• Habitat Resources

− Coastal Habitats (Chapter 4.3) 

− Deepwater Benthic Communities (Chapter 4.4) 

− Sargassum and Associated Communities (Chapter 4.5) 

− Live Bottom Habitats (Chapter 4.6) 

• Faunal Resources

− Fish and Invertebrate Resources (Chapter 4.7) 

− Birds (Chapter 4.8) 

− Protected Species (Chapter 4.9) 

• Social Environment

− Commercial Fisheries (Chapter 4.10) 

− Recreational Fishing (Chapter 4.11) 

− Recreational Resources (Chapter 4.12) 

− Archaeological Resources (Chapter 4.13) 

− Human Resources and Land Use (Chapter 4.14) 

The habitat resource chapters focus on the impact-producing factors that would affect their 

environment while the other chapters concentrate on the biological effects of impact-producing 

factors on fauna and human resources. To decrease repetition, the habitat information is generally 

not restated in the fauna chapters and vice versa.

Analysts concentrated on providing a focused analysis, using illustrations to communicate 

key concepts, and including more detailed, technical information in supporting appendices. 

Furthermore, supporting technical information in previous NEPA reviews have been developed as 

white papers and are summarized and incorporated by reference as appropriate. These white 

papers include the OCS Regulatory Framework (Cameron and Matthews, and 2016), Catastrophic 

Spill Event Analysis (USDOI, BOEM, 2017), Essential Fish Habitat Assessment (USDOI, BOEM, 

2016d), and Potential Lifecycle Greenhouse Gas Emissions and Social Cost of Carbon (Wolvovsky 

and Anderson, 2016). This Multisale EIS also tiers from and uses information contained in the Outer 

Continental Shelf Oil and Gas Leasing Program: 2017-2022; Final Programmatic Environmental 
Description of the Affected Environment and Impact Analysis 4-5

Impact Statement (Five-Year Program EIS; USDOI, BOEM, 2016b). Programmatic aspects of the 

potential impacts of climate change relative to the environmental baseline for the Gulf of Mexico 

OCS Program are discussed within each resource and in Chapter 4 of the Five-Year Program EIS.

This Multisale EIS was prepared with consideration of potential changes to or new 

information about the baseline conditions of the physical, biological, and socioeconomic resources. 

Current baselines (including past and present events) are described for all resources under their 

respective “Affected Environment” subchapters in this Multisale EIS. Past events such as 

Hurricanes Katrina and Rita and the Deepwater Horizon explosion, oil spill, and response have the 

potential to adversely affect multiple resources over a large area. Specific to the Deepwater 

Horizon, the Deepwater Horizon Natural Resource Trustees (Trustees) has completed the 

Deepwater Horizon Oil Spill: Final Programmatic Damage Assessment and Restoration Plan and 

Final Programmatic Environmental Impact Statement (PDARP/PEIS) (Deepwater Horizon Natural 

Resource Damage Assessment Trustees, 2016), which has the purpose and need of assessing and 

creating restoration plans to relieve injuries from the Deepwater Horizon explosion, oil spill, and 

response to natural resources and services. The injuries assessed within the PDARP/PEIS do not 

necessarily equate the baseline as defined in NEPA. The level of adverse effect depends on many 

factors, including the sensitivity of the resource as well as the sensitivity of the environment in which

the resource is located. All effects may not currently be known and some could take years to fully 

develop (refer to the “Incomplete or Unavailable Information” for each resource). The analyses of 

impacts from the Deepwater Horizon explosion, oil spill, and response on the physical, biological, 

and socioeconomic resources in this Multisale EIS are based on credible scientific information that 

was publicly available at the time this document was prepared. This credible scientific information 

was applied using accepted methodologies, including numerical modeling of data and scientific 

writing methods to convey the information of BOEM’s subject-matter experts’ technical knowledge 

and experience. However, BOEM and the Deepwater Horizon NRDA Trustee Council continue to 

study, measure, and interpret impacts arising out of that spill. BOEM continues to analyze the 

Deepwater Horizon explosion, oil spill, and response as information becomes available, and it was 

evaluated as part of the baseline for resources in this Multisale EIS. Thus, there are instances in 

which BOEM is faced with incomplete or unavailable information (refer to Chapter 4.0.2.4) that may 

be relevant to evaluating reasonably foreseeable significant adverse impacts on the human 

environment. Further, a low-probability catastrophic event and the resulting analysis of potential 

effects are presented in the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017).

4.0.1 What Encompasses the Affected Environment for a Gulf of Mexico Lease 

Sale?

Each resource chapter includes a unique description of the affected environment and an 

analysis of the potential environmental consequences of the alternatives for that particular resource. 

The Federal and State waters of the Gulf of Mexico and the adjacent coastal states are generally the 

affected environment described in each resource chapter. Current baselines are described for all 

resources under their respective “Affected Environment” sections. Specific to the PDARP/PEIS

(Deepwater Horizon Natural Resource Damage Assessment Trustees, 2016), the altered baseline 
4-6 Gulf of Mexico Multisale EIS

An impact-producing factor is an 

activity or process, as a result of a 

proposed lease sale, that could 

cause impacts on the 

environmental or socioeconomic 

setting. Chapter 3 provides a 

description of all possible impactproducing factors considered in 

this analysis.

An impact-producing factor is an 

activity or process, as a result of a 

proposed lease sale, that could 

cause impacts on the 

environmental or socioeconomic 

setting. Chapter 3 provides a 

description of all possible impactproducing factors considered in 

this analysis.

includes individual protected species directly affected by this unexpected unique catastrophic event. 

BOEM understands that each oil-spill event is unique and that its outcome depends on several 

factors, including time of year and location of the release relative to winds, currents, land, and 

sensitive resources, as well as specifics of the well and response effort. BOEM also understands 

that the severity of impacts from an oil spill cannot be predicated on volume alone. BOEM has 

analyzed a low-probability catastrophic event (USDOI, BOEM, 2017) in conjunction with its analysis 

of potential effects, as requested by CEQ pursuant to its regulation at 40 CFR § 1502.22. A 

low-probability catastrophic spill is, by definition, not reasonably certain to occur. Other methods of 

analysis are neither significantly limited in their applicability and availability nor would they provide 

any meaningful or useful information to be used to assess the risk of catastrophic spill occurrence at 

this programmatic level of oil and gas activities in the GOM. The return period of a catastrophic oil 

spill in OCS areas is estimated to be 165 years, with a 95 percent confidence interval between 

41 years and more than 500 years (Ji et al., 2014).

4.0.2 How are the Potential Environmental Consequences Determined?

The analyses of potential impacts to the wide variety of physical, environmental, and 

socioeconomic resources in the vast area of the GOM and adjacent coastal areas is very complex. 

For this Multisale EIS, a set of assumptions and a scenario were developed, along with descriptions 

of impact-producing factors that could occur from routine 

OCS oil- and gas-related activities, including accidental 

events. Analysis of the various alternatives considers these 

impact-producing factors (described in detail in Chapter 3) 

within a distinct framework that includes frequency, duration, 

and geographic extent. Frequency (whether rare, 

intermittent, or continuous) refers to how often the factor 

occurs over the entire analysis period of 50 years for routine 

activities and accidental events. Duration refers to how long 

the factor lasts from less than a year to many years. 

Geographic extent covers what areas are affected and, 

depending on the factor, how large of an area is affected.

Using this information, the interdisciplinary team of subject-matter experts applies knowledge 

and experience to conduct analyses of the potential effects of a proposed lease sale on assigned 

resources. Specialized education, experience, and technical knowledge are required of these 

subject-matter experts, as well as familiarity with the numerous impact-producing factors associated 

with OCS oil- and gas-related activities and other activities that can cause cumulative impacts in the 

area to conduct this analysis. Knowledge and practical working experience of major environmental 

laws and regulations such as NEPA, the Clean Water Act, Clean Air Act, Coastal Zone Management

Act (CZMA), ESA, Marine Mammal Protection Act, Magnuson-Stevens Fishery Conservation and 

Management Act, and others are also required to conduct this analysis. In order to accomplish this 

task, BOEM has assembled an interdisciplinary team with many years of collective experience. The 

vast majority of this team has advanced degrees with a high level of knowledge related to the 
Description of the Affected Environment and Impact Analysis 4-7

The potential magnitude of impact 

using these resource-specific 

definitions are provided in the 

introduction of most resource 

sections as a summary table to 

help the reader quickly identify the 

level of potential impacts for each 

impact-producing factor. The 

analysis supporting these 

conclusions are then discussed in 

detail in each resource chapter.

particular resources discussed in this chapter. This team prepares the input to BOEM’s lease sale 

EISs and a variety of subsequent postlease NEPA reviews, and is also involved with ESA, EFH

Assessment, and CZMA consultations. In addition, this same staff is also directly involved with the 

development of studies conducted by BOEM’s Environmental Studies Program. The results of these 

studies feed directly into the Bureau of Ocean Energy Management’s NEPA analyses.

How Were Impact Levels Defined?

The environmental consequences in each resource chapter include an analysis of applicable 

impact-producing factors from the categories of routine activities, accidental events, and cumulative 

impacts that would occur under any of the action alternatives (i.e, Alternatives A, B, C, and D).

It must be emphasized that, in arriving at the overall conclusions for certain environmental 

resources (e.g., birds, fisheries, and wetlands) for each alternative, the conclusions are based on 

potential impacts to the resources or species population as a whole, not to individuals, small groups 

of animals, or small areas of habitat. BOEM analyzes 

impacts on a finer geographic scale and mitigations that are 

appropriate for consideration through site-specific 

environmental reviews (refer to Appendix A). Each 

resource topic discussion includes a threshold effects 

determination and includes a resource-specific definition of 

impact level. Additionally, potential beneficial effects of a 

proposed action have also been considered and identified in 

individual resource chapters. For example, implementation 

of a proposed lease sale is anticipated to have beneficial 

impacts in the Area of Interest for economics due to the 

direct and indirect spending associated with the oil and gas 

industry. For this Multisale EIS, effects thresholds are 

defined using four categories of significance.

• Negligible – Impacts may or may not cause observable changes to natural 

conditions; regardless, they do not reduce the integrity of a resource.

• Minor – Impacts cause observable and short-term changes to natural conditions 

but they do not reduce the integrity of a resource.

• Moderate – Impacts cause observable and short-term changes to natural 

conditions and/or they reduce the integrity of a resource.

• Major – Impacts cause observable and long-term changes to natural conditions 

and they reduce the integrity of a resource.

The conclusions developed by BOEM’s subject-matter experts regarding the potential effects 

of a proposed lease sale for most resources are necessarily qualitative in nature; however, they are 

based on the science-based judgment of the highly trained subject-matter experts. Staff approach 
4-8 Gulf of Mexico Multisale EIS

this effort utilizing credible scientific information and apply it to the subject resources using accepted 

methodologies. It is important to note that, barring another catastrophic oil spill, which is a lowprobability accidental event not expected to occur and therefore not part of a proposed action, the 

adverse impacts associated with a proposed lease sale are expected to be small, and beneficial 

impacts are projected as well for certain activities and species. This is because of BOEM’s potential 

use of lease sale stipulations and mitigations, site-specific mitigations that may become conditions of 

plan or permit approval at the postlease stage, and mitigations required by other State and Federal 

agencies that help to reduce or minimize many of the impacts. Over the years, a suite of lease 

stipulations and mitigating measures has been developed to eliminate or ameliorate potential 

environmental effects, where implemented (refer to Appendix B, “Commonly Applied Mitigation 

Measures”). BOEM’s primary mitigative method is the avoidance of impacts, which is primarily 

implemented during approval of postlease activities. In many instances, these were developed in 

coordination with other natural resource agencies such as NMFS and FWS. Informal and formal 

consultation with other Federal agencies and affected States, and commenting opportunities for the 

public are implemented to assist in the development of the information and analyses in this Multisale 

EIS. Specifically, information requests soliciting input on the proposed lease sales were issued 

during scoping for this Multisale EIS (refer to Chapter 5). The impact-level conclusions reached in 

each resource area consider the applicable impact-producing factors, the level of activity, and the 

geographic area of each alternative.

Lease sale stipulations considered for a proposed lease sale include the Topographic 

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

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

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

Stipulation; Below Seabed Operations Stipulation; and the Stipulation on the Agreement between 

the United States of America and the United Mexican States Concerning Transboundary 

Hydrocarbon Reservoirs in the Gulf of Mexico (Transboundary Stipulation). The Topographic 

Features and Live Bottom (Pinnacle Trend) Stipulations have been applied as programmatic 

mitigation in the Five-Year Program EIS (USDOI, BOEM, 2016b) and, therefore, would apply to all 

leases issued under the Five-Year Program in designated lease blocks. Site-specific postlease 

mitigations may include buffer zones and avoidance criteria to protect sensitive resources such as 

areas of deepwater benthic communities, topographic features, and historic shipwrecks. Mitigations 

may also be required by other agencies (i.e., the U.S. Army Corps of Engineers and State CZM 

agencies) to avoid or reduce impacts from OCS oil- and gas-related activities, e.g., boring under 

beach shorelines and the rerouting of pipelines to reduce or eliminate impacts from OCS pipelines 

that make landfall. These mitigations and their potential effect on reducing or eliminating impacts 

from a proposed lease sale are analyzed in this chapter.

Under all four action alternatives, postlease activities would be reviewed on a case-by-case 

basis and the applicable commonly applied mitigating measures (refer to Appendix B) would be 

identified during site-specific reviews of plans and permits. This avoids excessive replication of 

discussion of similar if not identical impacts throughout the entire document, allowing the reader to 

focus on the differences between the alternatives.
Description of the Affected Environment and Impact Analysis 4-9

4.0.2.1 Routine Activities

The types of routine activities that could occur from all operations as a result of a single 

lease sale are described in Chapter 3.1. The major types of routine activities include geological and 

geophysical surveys; exploration, development, and production drilling; infrastructure emplacement 

and presence; transportation, including pipelines, vessels, and helicopters; discharges and wastes; 

decommissioning and removal; coastal infrastructure; air emissions; noise; and safety issues. The 

time period for postlease activities related to a single lease sale is 50 years.

4.0.2.2 Accidental Events

A summary of the information on accidental events that are reasonably foreseeable from all 

operations conducted under the OCS Program, as well as information on the number and sizes of 

spills from non-OCS sources is provided in Chapter 3.2. The types of accidental events that could 

reasonably be expected as a result of postlease activities include oil spills, losses of well control, 

accidental air emissions, pipeline failures, vessel and helicopter collisions, chemical and drilling-fluid 

spills, and spill response as a result of a proposed lease sale.

4.0.2.3 Cumulative Impacts

The cumulative analysis considers impacts to physical, biological, and socioeconomic 

resources that may result from the incremental impact of a proposed lease sale when added to all 

past, present, and reasonably foreseeable future human activities. However, most resources 

consider the past and present cumulative impacts as part of the baseline environmental conditions, 

and they are covered where relevant in the affected resource description. It is reasonably 

foreseeable to assume that lease sales would continue to occur, as they have historically, for many 

years to come in the Gulf of Mexico region, based on resource availability, existing infrastructure, 

and projected time lapses required for any other major energy sources to come online. However, 

the level of activities (exploration wells, production wells, and pipelines) becomes more speculative 

as time is projected further into the future. The causes for this are uncertainty in long-term oil price 

forecasts, resource potential, cost of development, and drill rig availability versus the amount of 

acreage leased from a lease sale. Furthermore, OCSLA provides for phased decisionmaking, each 

of which is a decision subject to NEPA. The OCSLA stages include the Five-Year Program stage to 

identify a schedule of leases over the period; the lease sale stage; the exploration stage; the 

development and production stage; and ultimately decisions on how a lessee may proceed with 

decommissioning. These reviews require consideration of cumulative impacts that would factor in 

changing environmental baselines, oil and gas price forecasts, and technology advancements, 

among others. Additionally, even though continued consumer demand is likely, new advances in 

technology (both on upstream development and production ends and downstream user ends) can 

potentially change the level of projected activities and how they are conducted. These could further 

minimize environmental risks. Technology advancements and organizational effectiveness could 

also further reduce projected air emissions, wastewater quantities, and other impact producing 

factors such as helicopter and vessel trips and accidental events.
4-10 Gulf of Mexico Multisale EIS

Therefore, cumulative impact assessment for this Multisale EIS considers existing 

environmental baseline conditions, past OCS and non-OCS activities in the GOM, projected future 

activities as a result of past lease sales, 50 years of incremental projected activities as a result of the 

proposed lease sales during the 2017-2022 Five-Year Program, and reasonably assumes projected 

activities for future lease sales based on current trends. Non-OCS oil- and gas-related activities 

include, but are not limited to, import tankering; marine transportation; State oil and gas activity; 

recreational, commercial, and military vessel traffic; offshore liquefied natural gas activity; 

recreational and commercial fishing; onshore development; and natural processes. The time period 

for reasonably foreseeable future actions are dependent upon the nature of each resource and are 

therefore defined in each resource chapter. The types of cumulative activities that could reasonably 

occur are described in Chapter 3.3. 

4.0.2.4 Incomplete or Unavailable Information

Throughout this chapter, where information was incomplete or unavailable, BOEM complied 

with its obligations under NEPA to determine if the information was relevant to reasonably 

foreseeable significant adverse impacts; if so, whether it was essential to a reasoned choice among 

alternatives; and, if it was essential, whether it can be obtained and whether the cost of obtaining the 

information is exorbitant, as well as whether scientifically credible information using generally 

accepted scientific methodologies can be applied in its place (40 CFR § 1502.22).

The most notable incomplete or unavailable information relates to some aspects of the 

effects from the Deepwater Horizon explosion, oil spill, and response. Credible scientific data 

regarding the potential short-term and long-term impacts from the Deepwater Horizon explosion, oil 

spill, and response on some GOM resources have become available. However, information relating 

to long-term effects continue to be studied and remain incomplete at this time, and it could be many 

years before this information becomes available. The Deepwater Horizon NRDA Trustees Council 

has released the PDARP/PEIS (Deepwater Horizon Natural Resource Damaage Assessment 

Trustees, 2016). However, the information collected during the NRDA process that the assessment, 

plan, and EIS used as a basis for their determinations are not yet publicly available (e.g., NRDA 

technical working group reports). There remains information being developed through the NRDA 

process, but it is not yet available as a final report. Nonetheless, BOEM’s subject-matter experts 

acquired and used newly available, scientifically credible information; determined that other 

additional information was not available absent exorbitant expenditures or could not be obtained 

regardless of cost in a timely manner; and where gaps remained, exercised their best professional 

judgment to extrapolate baseline conditions and impact analyses using accepted methodologies 

based on credible information. While incomplete or unavailable information could conceivably result 

in potential future shifts in baseline conditions of habitats that could affect BOEM’s decisionmaking, 

BOEM has determined that it can make an informed decision at this time without this incomplete or 

unavailable information. BOEM’s subject-matter experts have applied other scientifically credible 

information using accepted theoretical approaches and research methods, such as information on 

related or surrogate species. Moreover, BOEM will continue to monitor these resources for effects 
Description of the Affected Environment and Impact Analysis 4-11

caused by the Deepwater Horizon explosion, oil spill, and response, and will ensure that future 

BOEM environmental reviews take into account any new information that may emerge.

Furthermore, BOEM has considered the reasonably foreseeable impacts of a low-probability 

catastrophic oil spill in a white paper. These types of events, such as the one that resulted from the 

Deepwater Horizon explosion, are not reasonably expected to occur and therefore are not part of a 

proposed action. BOEM has prepared the Catastrophic Spill Event Analysis white paper, which 

provides a summary of existing credible scientific evidence related to this issue and BOEM’s 

evaluation of the potential impacts to the physical, biological, and socioeconomic resources and

conditions based upon theoretical approaches or research methods generally accepted in the 

scientific community (USDOI, BOEM, 2017). The white paper was included in previous lease sale 

EISs as an appendix. To avoid repetition and redundancies, the white paper is incorporated by 

reference and is publicly available on BOEM’s website at http://www.boem.gov/nepaprocess/. 

BOEM updated the analysis in the white paper and will update it again should new information 

become available relevant to the reasonably foreseeable impacts of a catastrophic spill event.

Alternatives

Each resource chapter includes an analysis of the relevant impact-producing factors to that 

specific resource from the routine activities, accidental events, and cumulative impacts that are 

described in Chapter 3. After this general analysis, the scale and location of these activities, events, 

and impacts are considered for each alternative.

4.0.2.5 Alternative A

In general, Alternative A could potentially result in 1.2-4.2 percent of the forecasted 

cumulative OCS oil and gas activity in the Gulf of Mexico and would occur in the WPA, CPA, and 

EPA portions of the proposed lease sale area. Most of the activity (up to 83%) of a proposed lease 

sale under Alternative A is expected to occur in the CPA and EPA portions of the proposed lease 

sale area, while up to 19 percent of the activity could occur in the WPA portion of the proposed lease 

sale area. Approximately 75.4 million acres (82%) of the regionwide lease sale area would be 

available for lease under this alternative.

4.0.2.6 Alternative B

Alternative B could potentially result in 1.0-3.6 percent of the forecasted cumulative OCS oil 

and gas activity in the Gulf of Mexico, or a slightly smaller amount of activity than proposed for 

Alternative A, and would be located geographically in the CPA and EPA portions of the proposed 

lease sale area. Approximately 49.6 million acres (54%) of the regionwide lease sale area would be 

available for lease. While all of the leases issued under this alternative would occur in the CPA and 

EPA portions of the proposed lease sale area, activities such as vessel support and pipeline or 

coastal infrastructure could occur in the WPA portion of the proposed lease sale area.
4-12 Gulf of Mexico Multisale EIS

4.0.2.7 Alternative C

Alternative C could potentially result in 0.2-0.6 percent of the forecasted cumulative OCS oil 

and gas activity in the Gulf of Mexico, which is much smaller than either Alternative A or B. 

Approximately 25.8 million acres (28%) of the regionwide lease sale area would be available for 

lease. While all of the leases issued under this alternative would occur in the WPA portion of the 

proposed lease sale area, activities such as vessel support and pipeline or coastal infrastructure

could occur in the CPA/EPA portion of the proposed lease sale area.

4.0.2.8 Alternative D

Under Alternative D, the number of blocks that would become unavailable for lease 

represents only a small percentage of the total number of blocks to be offered under Alternative A, 

B, or C (<4%, even if blocks subject to all three stipulations were excluded). However, it is also 

possible (and BOEM believes more reasonable to expect) that Alternative D would only shift the 

location of offshore infrastructure and activities farther from these sensitive zones and not lead to a 

reduction in offshore infrastructure and activities.

4.0.2.9 Alternative E

Under Alternative E, there would be no routine activities or accidental events as a result of a 

proposed lease sale. Therefore, there would be no associated impacts resulting from a proposed 

lease sale. Cancellation of a proposed lease sale, however, would not stop all OCS oil- and gasrelated activities. Activities related to previously issued leases and permits (as well as those that 

may be issued in the future under separate decision) related to the OCS oil and gas program would 

continue and could have impacts similar to those described in each resource chapter. However, no 

new activities related to a proposed lease sale would proceed and, therefore, those additional 

impacts would be avoided.

This chapter has thoroughly examined the existing credible scientific evidence that is 

relevant to evaluating the reasonably foreseeable significant impacts of a proposed lease sale and 

the alternatives on the environment. All reasonably foreseeable impacts, including beneficial ones, 

were considered. Impacts that could have catastrophic consequences, even if their probability of 

occurrence is low, not reasonably expected, and not part of a proposed action are considered in the 

Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017). Throughout this chapter, 

where information was incomplete or unavailable, BOEM complied with its obligations under NEPA

to determine if the information was relevant to reasonably foreseeable significant adverse impacts; if 

so, whether it was essential to a reasoned choice among alternatives; and, if it was essential, 

whether it can be obtained and whether the cost of obtaining the information is exorbitant, as well as 

whether credible scientific information applied using generally accepted scientific methodologies can 

be used in its place (40 CFR § 1502.22). BOEM has made conscientious efforts to comply with the 

spirit and intent of NEPA and to be comprehensive in its analyses of potential environmental 

impacts.
Description of the Affected Environment and Impact Analysis 4-13

4.1 AIR QUALITY

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

with a GOM proposed lease sale and its incremental contribution to the cumulative impacts to air 

quality are presented in this chapter. The approach of the analysis is to focus on the greatest 

reasonably foreseeable impact-producing factors from OCS oil- and gas-related routine activities 

(from exploration, development, and production), as well as accidental events and cumulative 

impacts, and to define the impact levels for each. The impact-producing factors considered and 

analyzed include (1) OCS oil- and gas-related emissions sources related to drilling and associated 

vessel support, production and the connected action of vessel support, flaring and venting, 

decommissioning, and oil spills; (2) other emissions not caused by OCS oil and gas development 

(i.e., non-OCS oil- and gas-related emissions such as State oil and gas programs, onshore industrial 

and transportation sources, and natural events); and (3) the incremental contribution of all postlease 

activities as a result of a single proposed lease sale. The impact-level definitions and the analyses 

supporting these conclusions are discussed in this chapter.

In order to assess the impacts from these oil- and gas-related activities, BOEM used an 

emissions inventory along with air dispersion and photochemical modeling. While an emissions 

inventory is an accounting of air emissions of criteria pollutants, precursors of criteria pollutants, and 

hazardous air pollutants from a variety of air emission sources, the comprehensive data from the 

inventory can be used to support air quality modeling. Typically, impacts are determined through 

modeling, and concentrations are reported. These impacts are then compared with reference 

measures, such as National Ambient Air Quality Standards (NAAQS), Significant Impact Levels, etc., 

to support impact conclusions. For this Multisale EIS analysis, BOEM used the following: (1) the 

results of the Year 2011 Gulfwide Emissions Inventory (GWEI) study, herein incorporated by 

reference (Wilson et al., 2014); (2) the changes in regulations as a result of the 2010 Deepwater

Horizon explosion, oil spill, and response to determine the impact-producing factors (Table 4-1) that 

have the greatest impact potential in the GOM region; and (3) the results of the “Air Quality Modeling 

in the Gulf of Mexico Region” study to determine impacts. Pollutants included the emissions 

inventory support analysis of air quality impacts in terms of impacts on the attainment of the NAAQS 

and on air quality-related values (AQRVs), including acid deposition and visibility. The results of the 

emissions inventory study and air modeling study are discussed later in this chapter. The “Air 

Quality Modeling in the Gulf of Mexico Region” study includes technical support documents 

(Appendices F-H) that provide detailed descriptions of the emissions data, meteorological and 

photochemical grid, modeling parameters and methodology, and the results of the air quality impact 

analysis.
4-14 Gulf of Mexico Multisale EIS

Table 4-1. Air Quality Impact-Producing Factors That Are Reasonably Foreseeable.

Air Quality Magnitude of Potential Impact1

Impact-Producing Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Drilling Minor Minor Minor Minor None

Production Minor Minor Minor Minor None

Vessel Support during 

Drilling and Production Minor Minor Minor Minor None

Routine Flaring and 

Venting Minor Minor Minor Minor None

Decommissioning Minor Minor Minor Minor None

Accidental Impacts

Emergency Flaring and 

Venting Minor Minor Minor Minor None

Oil Spills Minor Minor Minor Minor None

Cumulative Impacts

Incremental Contribution2 Minor Minor Minor Minor None

OCS Oil and Gas3 Moderate

Non-OCS Oil and Gas4 Moderate

1 The analysis supporting these conclusions is discussed in detail in the environmental consequences 

“Environmental Consequences” chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

Impact-Level Definitions

The following impact categories and definitions are used:

• Negligible – No measurable impact(s).

• Minor – Most impacts on the affected resource could be avoided with proper 

mitigation; if impacts occur, the affected resource would recover completely 

without mitigation once the impacting stressor is eliminated.

• Moderate – Impacts on the affected resource are unavoidable. The viability of 

the affected resource is not threatened although some impacts may be 

irreversible, or the affected resource would recover completely if proper 

mitigation is applied or proper remedial action is taken once the impacting 

stressor is eliminated.
Description of the Affected Environment and Impact Analysis 4-15

• Major – Impacts on the affected resource are unavoidable. The viability of the 

affected resource may be threatened although some impacts may be irreversible, 

and the affected resource would not fully recover even if proper mitigation is 

applied or remedial action is implemented once the impacting stressor is 

eliminated.

BOEM’s Gulf of Mexico OCS Region manages the responsible development of oil, gas, and 

mineral resources for the 430 million ac in the WPA, CPA, and a small portion of the EPA on the 

OCS comprising the GOM region. The Gulf of Mexico OCS area of possible influence includes the 

States of Texas, Louisiana, Mississippi, Alabama, and Florida. However, the Clean Air Act 

Amendments of 1990 designated air quality authorities in the GOM, giving BOEM air quality 

jurisdiction westward of 87°30' W. longitude and USEPA air quality jurisdiction eastward of 

87°30' W. longitude. The USEPA air quality jurisdiction includes part of the CPA and all of the EPA, 

while BOEM’s air quality jurisdiction includes most of the CPA and all of the WPA. This separation 

of authority is depicted in Figure 4-1. In 2006, oil and gas leasing operations within 125 mi (201 km) 

of the Florida coastline were placed under moratorium until 2022 under the Gulf of Mexico Energy 

Security Act (GOMESA). The GOMESA moratoria area is depicted on Figure 2-1. 

Figure 4-1. Gulf of Mexico Region with the Planning Areas, Nonattainment Areas, Air Quality

Jurisdiction, and Class I and Sensitive Class II Areas. (Note: The South Atlantic Planning 

Area was removed from the Five-Year Program.)

BOEM is required under the OCSLA (43 U.S.C. § 1334(a)(8)) to develop regulations to 

ensure compliance with the NAAQS to the extent that OCS offshore oil and gas exploration, 

development, and production sources do not significantly affect the air quality of any state pursuant 

to the NAAQS. Since the primary NAAQS are designed to protect human health, BOEM focuses 
4-16 Gulf of Mexico Multisale EIS

this Multisale EIS analysis on the impact of these activities on the States, where there are 

permanent human populations. However, the potential impacts for the whole Gulf of Mexico region 

were modeled, including the impacts at the State/seaward boundary of Gulf Coast States (3-9 nmi 

[3.45-10.36 mi; 5.56-16.67-km] from shore, depending on the State). Detailed potential impacts from 

the “Air Quality Modeling in the Gulf of Mexico Region” study are included in Appendix H. 

4.1.1 Description of the Affected Environment

For this Multisale EIS analysis, the affected environment comprises the WPA, CPA, and 

EPA, including the States of Texas, Louisiana, Mississippi, Alabama, and Florida, and the respective 

State waters. This area also includes national parks and Federal wilderness areas where air quality

and AQRVs (primarily visibility) are protected more stringently than under the NAAQS. These 

protected Class I areas in the GOM region include the following: the Breton Wilderness Area in 

Louisiana; and the Bradwell Bay Wilderness Area, Chassahowitza National Wilderness Area, 

Everglades National Park, and St. Marks Wilderness Area in Florida.

The Clean Air Act Amendments of 1977 designated 156 Class I areas, consisting of national 

parks and wilderness areas that are offered special protection for air quality and the AQRVs. The 

Class I areas, compared to the Class II areas, have lower PSD air quality increments that new 

sources may not exceed and are protected against excessive increases in several AQRVs, including 

visibility impairment, acid (sulfur and nitrogen) deposition, and nitrogen eutrophication. The 

Regional Haze Rule (40 CFR § 51.308) has a goal of natural visibility conditions by 2064 at Class I 

areas, and States must submit Regional Haze Rule State Implementation Plans that demonstrate 

progress towards that goal. Figure 4-1 displays the locations of the mandatory Class I areas in the 

GOM region.

While not included in the Clean Air Act Amendments of 1977 as an area of special 

protection, Federal management agencies have designated certain other areas as sensitive Class II 

areas for tracking PSD increment consumption and AQRV impacts. The sensitive Class II areas, 

designated as such in the GOM region, include the Padre Island National Seashore and Gulf Islands 

National Seashore. Since Class I and sensitive Class II areas are of concern, the areas located in or 

nearby the GOM region are discussed in this Multisale EIS and are shown in Figure 4-1. 

Clean Air Act and the Clean Air Act Amendments Overview

The Clean Air Act of 1970 established the NAAQS, which include the primary standards to 

protect public health and secondary standards to protect public welfare including visibility and 

vegetation. Under the Clean Air Act, USEPA is periodically required to review and, as appropriate, 

modify the criteria based on the latest scientific knowledge. Several revisions to the NAAQS have 

occurred in the past few years as more is understood about the effects of the pollutants. The current 

NAAQS, shown in Table 4-2, address six pollutants: carbon monoxide (CO); nitrogen dioxide (NO2); 

particulate matter (PM2.5 and PM10); sulfur dioxide (SO2); lead (Pb); and ozone (O3).
Description of the Affected Environment and Impact Analysis 4-17

Table 4-2. National Ambient Air Quality Standards.

Pollutant

(Final Rule Citation)

Primary/

Secondary

Averaging

Time Level Form

Carbon Monoxide (CO)

(Federal Register, 2011a) Primary

8-hour 9 ppm Not to be exceeded more 

1-hour 35 ppm than once per year

Lead (Pb)

(Federal Register, 2008b)

Primary and 

Secondary

Rolling 

3-month 

average

0.15 μg/m3(1) Not to be exceeded

Nitrogen Dioxide (NO2) 

(Federal Register, 2010a)

(Federal Register, 1996)

Primary 1-hour 100 ppb 98th percentile, averaged 

over 3 years

Primary and 

Secondary Annual 53 ppb(2) Annual mean

Ozone (O3) 

(Federal Register, 2015f)

Primary and 

Secondary 8-hour 0.070 ppm(3)

Annual 4th-highest daily 

maximum 8-hour 

concentration, averaged 

over 3 years

Particle Pollution

(Federal Register, 

2013)

(Federal Register, 

2006a)

PM2.5

Primary Annual 12 μg/m3 Annual mean, averaged 

over 3 years

Secondary Annual 15 μg/m3 Annual mean, averaged 

over 3 years

Primary and 

Secondary 24-hour 35 μg/m3 98th percentile, averaged over 3 years

PM10

Primary and 

Secondary 24-hour 150 μg/m3

Not to be exceeded more 

than once per year on 

average over 3 years

Sulfur Dioxide (SO2) 

(Federal Register, 2010b)

(Federal Register, 1973a)

Primary 1-hour 75 ppb(4)

99th percentile of 1-hour 

daily maximum 

concentrations, averaged

over 3 years 

Secondary 3-hour 0.5 ppm Not to be exceeded more 

than once per year

(1) The Final Rule was signed on October 15, 2008. The 1978 lead standard (1.5 μg/m3 as a quarterly 

average) remains in effect until 1 year after an area is designated for the 2008 standard. Areas 

designated nonattainment under the 1978 standard remain in effect until implementation plans are 

approved to attain or maintain the 2008 standard.

(2) The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for 

the purpose of clearer comparison to the 1-hour standard.

(3) The final rule was signed on October 1, 2015, and became effective on December 28, 2015. The 

previous (2008) O3 standards additionally remain in effect in some areas. Revocation of the previous 

(2008) O3 standards and transitioning to the current (2015) standards will be addressed in the 

implementation rule for the current standards.

(4) The Final Rule was signed on June 2, 2010. The 1971 annual and 24-hour SO2 standards were 

revoked in that same rulemaking. However, these standards remain in effect until 1 year after an 

area is designated for the 2010 standard, except in areas designated nonattainment for the 1971 

standards, where the 1971 standards remain in effect until implementation plans to attain or maintain 

the 2010 standard are approved.

Notes: PM – particulate matter; ppb – parts per billion; ppm – parts per million.

Source: USEPA, 2015d.
4-18 Gulf of Mexico Multisale EIS

The Clean Air Act establishes classification designations based on regional monitored levels 

of ambient air quality. These designations impose mandated timetables and other requirements 

necessary for attaining and maintaining healthful air quality in the U.S. based on the seriousness of 

the regional air quality problem. These designations are nonattainment, attainment, and 

unclassifiable. Nonattainment is any area that does not meet the national primary or secondary 

ambient air quality standard for the pollutant. When measured concentrations of these regulated 

pollutants exceed the standards established by the NAAQS, the number of exceedances and the 

concentrations determine the nonattainment classification of an area. The Clean Air Act 

Amendments of 1990 established these designations as marginal, moderate, serious, severe, and 

extreme. Attainment is any area that meets the national primary or secondary ambient air quality 

standard for the pollutant. Unclassifiable is any area that cannot be classified on the basis of 

available information as meeting or not meeting the national primary or secondary ambient air quality 

standard for the pollutant. Figure 4-1 depicts all of the current nonattainment areas in the GOM 

region.

The Federal OCS waters are unclassifiable. The OCS areas are not classified because 

there is no regulatory provision for any classification in the Clean Air Act for waters outside of the 

boundaries of State waters. Only areas within State boundaries can be classified as either 

attainment or nonattainment.

Gulf of Mexico OCS Region Attainment Status

After promulgation of a NAAQS, USEPA designates areas that fail to achieve the NAAQS as 

nonattainment areas, and States are required to submit State Implementation Plans to USEPA; 

these plans contain emission control plans and a demonstration that the nonattainment area would 

achieve the NAAQS by the required date. After an area comes into attainment of the NAAQS, the 

area can be redesignated as a maintenance area and must continue to demonstrate compliance 

with the NAAQS. Figure 4-1 depicts all the current nonattainment areas in the GOM region while 

Table 4-3 summarizes the nonattainment and maintenance areas in the GOM region. Sulfur dioxide 

(SO2) and lead (Pb) nonattainment areas are focused around specific large industrial sources of SO2

or lead emissions, whereas ozone nonattainment areas are more regional in nature, reflecting the 

formation of ozone as a secondary pollutant from emissions of nitrogen oxides (NOx) and volatile 

organic compound (VOC) precursors from a wide range of sources. (Note: As November 1, 2016, 

USEPA proposed to redesignate the Baton Rouge, Louisiana, area as being in attainment of Federal 

health-based ozone standards. The State of Louisiana requested that the redesignation, based on 3 

years of air quality data showing the metropolitan areas of Ascension, East Baton Rouge, Iberville, 

Livingston, and West Baton Rouge Parishes, meet the 2008 8-hour ozone standard of 0.075 parts 

per million [ppm]. The USEPA also proposes to approve the State’s plan for maintaining the 

standard.)
Description of the Affected Environment and Impact Analysis 4-19

Table 4-3. Nonattainment and Maintenance Areas in the Gulf of Mexico Region.

State Area 8-hr O3

(1997)

8-hr O3

(2008)

SO2

(2010)

Lead

(2008)

Alabama Troy NAA

Florida

Tampa NAA

Hillsborough County NAA

Nassau County NAA

Louisiana Baton Rouge M NAA

St. Bernard Parish NAA

Texas

Beaumont-Port Arthur M

Houston-Galveston-Brazoria NAA NAA

Frisco NAA

M = maintenance area; NAA = nonattainment area; O3 = ozone; SO2 = sulfur dioxide.

Blank cells indicate the area is in attainment of the National Ambient Air Quality Standards. 

As previously mentioned, USEPA periodically modifies the NAAQS criteria based on new 

scientific knowledge. On October 1, 2015, USEPA strengthened the 8-hour NAAQS for ozone to 

0.07 ppm (70 parts per billion [ppb]). Under this more stringent ozone NAAQS, there may be more 

areas in the southeastern U.S. designated as nonattainment. The USEPA plans to make attainment 

and nonattainment designations for the revised standards by October 2017, with the designations 

based on 2014-2016 air quality monitoring data.

In February 2010, USEPA issued a new 1-hour NO2 NAAQS with a threshold of 100 ppb 

(98th percentile daily maximum average over 3 years), and a new 1-hour SO2 NAAQS was 

promulgated in June 2010 with a threshold of 75 ppb (99th percentile averaged over 3 years). The 

USEPA has not yet designated the nonattainment areas for the 1-hour NO2 and 1-hour SO2 NAAQS.

A Pb NAAQS was issued in 2008; nonattainment areas for lead are associated with specific 

industrial sources. The USEPA has not yet designated the nonattainment areas for the Pb NAAQS.

The CO NAAQS has remained essentially unchanged since it was originally promulgated in 

1971. As of September 27, 2010, all prior CO nonattainment areas throughout the country have 

been redesignated as maintenance areas.

Emissions Inventories

One of the most accurate methods for estimating air emissions is by developing a 

comprehensive emissions inventory. To develop a calendar year 2011 inventory of criteria 

pollutants, criteria precursors, and greenhouse gas emissions for all OCS oil and gas productionrelated sources in the GOM, BOEM collected activity data from platform operators during the year 

2011. On September 15, 2010, NTL 2010-G06 was published to introduce the “2011 Gulfwide OCS 

Emissions Inventory (Western Gulf of Mexico)” and inform operators about the mandatory data 

collection. Affected operators are lessees and operators of Federal oil, gas, and sulfur leases in the 
4-20 Gulf of Mexico Multisale EIS

Gulf of Mexico OCS region west of latitude 87.5°. The USEPA jurisdiction has air quality jurisdiction 

east of latitude 87.5°.

BOEM updated and distributed a Microsoft® Visual Basic® program for platform operators to 

use to collect activity data on a monthly basis and submit to BOEM on an annual basis. The 

program, known as GOADS-2011, was used by operators to submit activity data for a number of 

production platform emission sources. Operators used the GOADS software to collect activity data 

for amine units, boilers/heaters/burners, diesel engines, drilling equipment, fugitives, combustion 

flares, glycol dehydrators, losses from flashing, mud degassing, natural gas engines, natural 

gas/diesel/dual-fuel turbines, pneumatic pumps, pressure/level controllers, storage tanks, and cold 

vents. These activity data were used to calculate CO, NOx, SO2, PM10, PM2.5, and VOC emissions 

estimates, as well as CO2, CH4, and N2O. The Gulfwide Oracle® DBMS calculates and archives the 

activity data and the resulting emissions estimates. Database users can query by pollutant, month, 

equipment type, platform, etc. Emission estimates for non-platform sources on the Gulf of Mexico 

OCS include both oil and natural gas production-related sources, as well as non-oil and natural gas 

sources. Production sources consist of survey vessels, drilling rigs, pipe-laying operations, and 

support vessels and helicopters. Non-oil and natural gas sources 

include commercial marine vessels, the Louisiana Offshore Oil 

Platform (LOOP), and biogenic and geogenic sources. Ultimately, 

State agencies and Regional Planning Organizations will use these 

offshore oil and gas platform and non-platform inventories to 

perform modeling for ozone and regional haze for use in their State 

Implementation Plans, and BOEM will use the emission inventory 

for the cumulative impact analysis in NEPA documents.

Emissions estimates calculated in the study were used to support analysis of air quality

modeling impacts. In this inventory, emissions estimates are provided for directly emitted pollutants. 

While there are national air quality standards for six common air quality pollutants, only four of these 

pollutants (i.e., CO, Pb, NO2, and SO2) are directly emitted. Indirect emissions and the formation of 

other pollutants, as well as pollutants not included in the inventory, are analyzed below.

• Greenhouse Gases. Fluorinated gases, hydrofluorocarbons, and sulfur 

hexafluoride are not covered in this inventory because they are used in trace 

amounts and at no time are deliberately emitted into the atmosphere.

• Lead. Lead (Pb), a NAAQS criteria pollutant, is not covered in this inventory 

because oil and gas sources have negligible lead emissions. Since unleaded 

fuels have been phased out, lead remains a trace contaminant in other fuels 

(USEPA, 2016c).

• Nitrogen Dioxide. Nitrogen dioxide (NO2), a NAAQS criteria pollutant, is one of a 

group of highly reactive gases known as nitrogen oxides (NOx). Nitrogen oxides 

are stated as an equivalent mass of NO2; consequently, NOx is used instead of 

NO2. 

2011 GWEI Pollutants

• NAAQS: CO, NOx, 

PM2.5, PM10, SO2

• Criteria Precursors: 

VOC

• Greenhouse Gases: 

CO2, CH4, N2O 
Description of the Affected Environment and Impact Analysis 4-21

• Particulate Matter. Particulate matter (PM), a NAAQS criteria pollutant 

expressed as PM2.5 and PM10, can be emitted directly or it can be formed in the 

atmosphere when emissions of NOx, sulfur oxides (SOx), ammonia, organic 

compounds, and other gases react in the atmosphere. According to USEPA’s 

“Particulate Matter Emissions Report,” coarse PM (PM10) is composed largely of 

primary particles, while a much greater portion of fine PM (PM2.5) contains 

secondary particles. “Primary” particles are those released directly to the 

atmosphere whereas “secondary” particles are formed in the atmosphere from 

chemical reactions involving primary gaseous emissions. While both PM2.5 and 

PM10 are included the inventory, the secondary formation is not included the 

inventory because secondary PM is not directly emitted. Since USEPA has not 

developed separate PM2.5 and PM10 emissions factors per source, particulatematter emission estimates of PM2.5 and PM10 are similar. Therefore, PM10 values 

have been used in this chapter to represent particulate matter emission 

estimates.

• Ozone. Ozone (O3), an NAAQS pollutant, is not directly emitted into the air but is 

formed by photochemical reactions of NOx and VOCs in the presence of sunlight. 

Since NOx and VOCs are directly emitted pollutants, they are included in the 

emissions inventory, and their resulting emission estimates are used in the air 

quality model to analyze the air quality impacts of O3. 

Summary of Results of the Year 2011 Gulfwide Emissions Inventory

The Year 2011 GWEI results indicate that OCS oil and gas production platform and nonplatform sources emit the majority of NAAQS criteria pollutants, VOCs, and greenhouse gases on 

the Gulf of Mexico OCS, with the exception of SO2 (primarily emitted from commercial marine 

vessels), and N2O (from biological sources) (Wilson et al., 

2014). The total platform and non-platform emission 

estimates for criteria pollutants and the total platform and 

non-platform emission estimates for greenhouse gases 

are depicted in Figures 4-2 and 4-3, respectively. In both 

figures, total emission estimates are subdivided into three 

main categories: total non-OCS oil/gas source emissions; 

total OCS oil/gas non-platform source emissions; and total 

OCS oil/gas platform source emissions.

Total emissions estimates include

• total non-OCS oil and gas 

source emissions,

• total OCS oil and gas nonplatform source emissions, and 

• total OCS oil and gas platform

production source emissions.
4-22 Gulf of Mexico Multisale EIS

Figure 4-2. Year 2011 Gulfwide Emission Inventory Results for Total Platform and Non-Platform Criteria 

Pollutant Emissions (TPY).

Figure 4-3. Year 2011 Gulfwide Emission Inventory Results for Total Platform and Non-Platform 

Greenhouse Gas Emissions (TPY). 

OCS Oil and Gas Platform 

Sources

OCS Oil and Gas Non Platform 

Sources

Non-OCS Oil and Gas Sources 

OCS Oil and Gas Platform 

Sources

OCS Oil and Gas Non Platform 

Sources

Non-OCS Oil and Gas Sources 
Description of the Affected Environment and Impact Analysis 4-23

Natural gas engines on platforms represented the 

largest CO emission source, and support vessels were the 

highest emitters of both NOx and PM10. Oil and natural gas 

production platform vents account for the highest percentage 

of the VOC emissions. Support vessels; production platform 

natural gas, diesel, and dual-fuel turbines; and commercial 

marine vessels emit the majority of the greenhouse gas 

emissions.

The Year 2011 GWEI results for criteria pollutant and greenhouse gas emissions (in 

tons/year) from platform sources are depicted in Figures 4-4 and 4-5, respectively. In both figures, 

each platform source emission type is represented per pollutant in tons/year.

Figure 4-4. 2011 Criteria Pollutant Emissions (TPY) from Platform Sources.

Figure 4-5. 2011 Greenhouse Gases (TPY) from Platform Sources.

Platform sources include

• criteria pollutants,

• emissions in (TPY),

• greenhouse gases, and

• emissions in (TPY).
4-24 Gulf of Mexico Multisale EIS

The Year 2011 GWEI results for criteria pollutant and greenhouse gas emissions (in 

tons/year) from non-platform sources (not pictured) indicate that support vessels emit the majority of 

the greenhouse gas emissions, as well as the highest emitter of both NOx and PM10 criteria 

pollutants.

4.1.2 Environmental Consequences

The impact-producing factors and their potential impacts identified for routine activities, 

accidental events, cumulative impacts, and incomplete or available information would apply, in 

general, to Alternatives A-D. These analyses are then applied to each alternative based on the 

varying degrees of forecasted levels of activities by geographical area and water depth. Following 

this environmental consequences discussion, there will be a summary of the potential impacts as 

they relate to the alternatives.

As discussed in the air quality introduction, the following list of impact-producing factors can 

occur in routine activities, accidental events, and cumulative impacts. The impact-producing factors 

include (1) OCS oil- and gas-related emissions sources related to drilling and associated vessel 

support, production, and the connected action of vessel support, flaring and venting, 

decommissioning, and oil spills; (2) non-OCS oil- and gas-related emissions such as State oil and 

gas programs, onshore industrial and transportation sources, and natural events; and (3) the 

incremental contribution of all postlease activities as a result of a single proposed lease sale. These 

impact-producing factors can produce greenhouse gas and fugitive emissions, which are discussed 

below.

Greenhouse Gases and Fugitive Emissions

Greenhouse Gases Including Downstream Gas

Chief among drivers of climate change are increasing atmospheric concentrations of carbon 

dioxide (CO2) and other greenhouse gases, such as methane (CH4) and nitrous oxide (N2O). These 

greenhouse gases reduce the ability for solar radiation to re-radiate out of the Earth’s atmosphere 

and into space. Although all three have natural sources, these three greenhouse gases comprise 

the majority of greenhouse gases released from anthropogenic sources; CO2 and N2O are released 

in association with combustion and CH4 and N2O are released as a byproduct of agriculture and also 

oil and gas production. Hydrofluorocarbons and sulfur hexafluoride are two fluorinated greenhouse 

gases that are used on the OCS, but they are used in trace amounts and are at no time deliberately 

emitted into the atmosphere.

The activities associated with a proposed action would increase global greenhouse gas 

emissions from the use of vessels, drilling equipment, and other activities that burn fossil fuels. In 

addition, CH4, also known as natural gas, is removed from wells and brought onto OCS facilities 

along with oil being produced. Sometimes CH4 is released as a fugitive gas that can escape 

unintentionally from leaks in equipment used by operators. Operators have the four following 

methods of managing natural gas removed from wells: (1) production – selling the natural gas, 
Description of the Affected Environment and Impact Analysis 4-25

provided there is a sufficient quantity, favorable market conditions, and infrastructure (e.g., natural 

gas pipelines) to justify production; (2) reinjection – the natural gas is directed back into the reservoir 

to aid in oil extraction; (3)venting – the deliberate release of natural gas into the atmosphere; and 

(4) flaring – burning the natural gas, converting it to CO2 and water, and in some cases, also 

releasing N2O and black carbon. This practice is rare on the OCS.

Because each greenhouse gas impacts the atmosphere at a different strength and for a 

different period of time, for analytical purposes, they typically are converted to what the strength 

would be if emissions were exclusively CO2; this is referred to as the CO2-equivalent (CO2e) to 

facilitate comparison. CH4 and N2O are much more effective climate forcers than CO2, meaning 

1 ton of CH4 or N2O has a greater impact on climate change than 1 ton of CO2. However, CH4 and 

N2O are removed from the atmosphere through natural processes more efficiently than CO2. 

Accounting for these factors, CO2e conversion for CH4 and N2O are 25 and 298, respectively 

(Ecometrica, 2012). This means that 1 ton of CH4 is estimated to have the same warming potential 

as 25 tons of CO2, and 1 ton of N2O would have the same impact as 298 tons of CO2. Because 

black carbon is not a greenhouse gas and functions differently, it is not possible to convert it using 

the CO2e method. However, because black carbon is a specific kind of PM2.5, it is possible to use 

the PM2.5 concentration to estimate the maximum amount of black carbon released. BOEM has 

regulatory authority on the OCS for PM2.5, along with several other air quality pollutants.

As a result of exploration, development, and production of oil and gas on the OCS, the 

activities associated with a proposed action are expected to release greenhouse gases and black 

carbon from the use of combustion engines in vessels, construction, drilling, and other equipment, 

as well as through the deliberate or accidental release of CH4. Emissions estimates for the activities 

associated with a proposed action, and for cumulative BOEM-related OCS emissions, were 

calculated using the Offshore Environmental Cost Model. These estimates are for the high-price 

scenario, which would likely result in the highest level of potential emissions for a proposed action. 

Cumulative numbers include current operations, the activities associated with a proposed action, 

and expected future development beyond a proposed action. Unlike the greenhouse gases, which 

warm the planet generally, black carbon’s potential to contribute to climate change has a spatial 

component. Compared with the 2012-2017 Five-Year Program, the activities associated with a 

proposed action would result in an overall increase in the rate of CO2e emissions from OCS oil- and 

gas-related activities.

In addition to the direct emissions from OCS oil- and gas-related operations presented 

above, BOEM has evaluated greenhouse gas emissions covering the lifecycle of OCS oil and gas 

production and consumption. This includes both the “downstream” consumption and onshore 

processing of oil and gas products, as well as the “upstream” emissions from offshore exploration, 

development, and production.

The expected greenhouse gas emissions for the low- and high-price scenarios include 

numerous assumptions (Wolvovsky and Anderson, 2016); therefore, while being a reasonable 

approximation, these numbers are an estimate and not a forecast. However, because the 
4-26 Gulf of Mexico Multisale EIS

methodology used to compare the two price scenarios and the No Action Alternative are the same, 

the analysis can be assumed to provide a relative comparison. There is a significant degree of 

uncertainty in these numbers, and they do not take into account future Federal, State, and/or local 

economic, social, policy, regulatory, and legislative changes that could affect the amount of 

greenhouse gases released. In addition, this analysis is bounded by U.S. consumption and the 

upstream domestic and overseas production supporting American consumption. This means that 

the likely overseas reduction in consumption under the No Action Alternative is not calculated in this 

analysis.

On April 22, 2016, the United States joined the Paris Agreement, a United Nations-brokered 

agreement to keep global temperatures within 2 °C (36 °F) of the pre-industrial climate, and 

preferably within 1.5 °C (35 °F) (United Nations Framework Convention on Climate Change, 2016). 

A recent study (McGlade and Ekins, 2015) states that, to prevent the planet from warming beyond 

2 °C (36 °F), emissions of greenhouse gases must be kept below 1,100 billion tons of CO2e between 

2011 and 2050. McGlade and Elkins (2015) also discuss the need to greatly reduce the amount of 

oil and gas extraction to stay under this threshold, with particular emphasis on not drilling in the 

Arctic. It should be noted that the 2 °C (36 °F) warming threshold would still result in significant 

impacts on the world’s ecosystems and to humanity (Hansen et al., 2016).

The U.S. has pledged to reduce emissions by filing an Intended Nationally Determined 

Contributions with the United Nations. The American Intended Nationally Determined Contributions 

commitment is to reduce net greenhouse gas emissions by 17 percent below 2005 levels by 2020 

and by 26-28 percent by 2025 (United Nations Framework Convention on Climate Change, 2016). 

In addition, the Obama Administration has set a target to reduce U.S. greenhouse gas emissions by 

at least 80 percent by 2050 (The White House, 2015). In 2005, the U.S. had net emissions of 

6,680,300,000 metric tons of CO2e (Ecometrica, 2012).

The activities associated with the proposed action’s lifecycle emissions fluctuate over the 

course of the 2017-2022 Five-Year Program, with early emissions largely coming from OCS 

sources. The greenhouse gas emissions would peak in the 2030s and 2040s, at the same time as 

production peaks. Overall, the greenhouse gases from the activities associated with the proposed 

action would be similar to but slightly lower than the No Action Alternative in both low- and high-price 

scenarios. This similarity is due to the economic substitution effects from onshore and overseas 

sources expected under the No Action Alternative.

Additional sector-specific goals, such as the United States’ commitment with Canada and 

Mexico to achieve 50 percent of electricity from noncarbon sources (The White House, 2016) and 

other yet-to-be determined measures, could significantly affect how oil and gas products are used 

and the emissions resulting from that consumption. Policies already determined and implemented 

have been included in the lifecycle analysis. The high- and low-price scenarios are intended to 

provide the upper and lower bounds of possible emissions scenarios. Overall, implementation of 

U.S. climate goals through future policies and regulations would be expected to reduce overall oil 
Description of the Affected Environment and Impact Analysis 4-27

and gas demand, making it unlikely that the estimated emissions presented for the high-price 

scenario would be realized.

Fugitive Emissions

Fugitive emissions are not intentionally released through a stack, vent, or flare, but they are 

instead caused by leaks or intermittently escapes from pressurized equipment from sealed surfaces 

in various components of the facility. Fugitive emissions are mainly comprised of VOCs and 

methane (CH4). Sources of fugitive emissions typically include valves, flanges, connectors, pumps, 

and compressor seals, but they may also include other platform components such as pneumatic 

controllers. Fugitive emissions can occur during all phases of OCS oil- and gas-related activity.

According to the Year 2011 GWEI study, fugitive emissions constitute one of the largest 

VOCs and CH4 emissions sources from offshore oil and gas platforms, behind only cold vents. The 

BSEE personnel have indicated that the infrared camera surveys, performed to detect hydrocarbon 

leaks during inspections of offshore platforms, show very few, if any, hydrocarbon leaks. This could 

imply that the current emission factors may be overestimating VOC and methane emissions. 

Several State coastal areas have been designated nonattainment for ozone. Since ozone is formed 

by the combination of VOCs and NOx, the OCS emissions inventory for VOCs needs to be as 

accurate as possible. In addition, the Government Accountability Office has published Opportunities 

Exist to Capture Vented and Flared Natural Gas, Which Would Increase Royalty Payments and 

Reduce Greenhouse Gases (U.S. Government Accountability Office, 2010) looking to reduce CH4

emissions by the installation of control technology on platforms. Before control technology is 

required, the OCS emissions inventory for CH4 also needs to be as accurate as possible. 

Based on the results of the emission inventory study, as well as correspondence with BSEE, 

and the GAO report, BOEM wants to further assess emissions from fugitive equipment leaks on 

offshore oil and gas platforms operating on the Gulf of Mexico OCS. Under BOEM’s Contract 

Number M16PC00010, “Fugitive Emissions Update in the Outer Continental Shelf,” the objective is 

to visit offshore production platforms to identify and conduct the testing of fugitive equipment leaks in 

order to develop updated VOC, select hazardous air pollutant, and methane emission factors. 

These updated emission factors would be used by BOEM to develop improved and contemporary 

emissions inventories that will be used for a variety of purposes, including future photochemical grid 

modeling conducted by states in the Gulf of Mexico region for State Implementation Plan compliance 

demonstrations. However, if the OCS emissions inventories are overestimating VOC and methane 

emissions, then possibly control technologies would not be required. These study results are 

projected to be available by spring of 2019. Otherwise, BOEM would determine the appropriate use 

of control technologies on the platforms during postlease reviews.

4.1.2.1 Routine Activities

The primary routine impact-producing factors associated with the proposed action that could 

potentially affect air quality and that also could contribute to climate change include (1) drilling and 

production and the associated vessel support, (2) flaring and venting, and (3) decommissioning of 
4-28 Gulf of Mexico Multisale EIS

facilities. These routine activities result in pollutant emissions. Emissions of air pollutants from 

these activities would occur during exploration, development, production, and decommissioning 

activities.

Drilling and Production with Associated Vessel Support

Since both drilling and production activities include associated vessel support, the activities 

are analyzed together in this section. Emissions during exploration are higher than emissions during 

development due to power requirements for drilling a deeper wellbore hole. During drilling, diesel 

engines are used to power the drilling (top drive) assembly, draw works, electrical generators, mud 

pumps, vessel propulsion (drillships and support vessels)), and dynamic positioning systems of the 

drilling rig (if a dynamic positioning semisubmersible or dynamic positioning drillship is used). 

Combustion of fuel to run the engines generates NAAQS criteria pollutants, VOCs, and greenhouse 

gases. More information about the pollutants that are generated by specific equipment and activities 

is available in the Year 2011 Gulfwide Emission Inventory Study (Wilson et al., 2014). As illustrated 

in Figure 3-2, during a 50-year analysis period, exploratory drilling mainly occurs during the first 

decade and development drilling extends throughout the first and second decade.

We know from Chapter 3 that, during production, pollutants emitted during routine activities 

may be combustion products of burning fuel to power pumps, compressors, or generators, or they 

may consist of fugitive VOCs, which escape from the un-combusted hydrocarbons. The platform 

emission sources include boilers, turbines, pneumatic pumps, diesel engines, combustion flares, 

fugitives, glycol dehydrators, natural gas engines, pressure/level controllers, storage tanks, cold 

vents, and others. As illustrated in Figure 3-2, during a 50-year analysis, most production occurs 

during the second and third decade. Because the levels of activity in the 2011 GWEI are projected 

to be less than a proposed lease sale, these emission values are used to project potential impacts 

as described below.

The OCS emissions in tons per year for the criteria pollutants and for the greenhouse gases 

from platform sources are indicated in Figures 4-4 and 4-5. The distribution of emissions across 

various platforms sources would be expected to be similar. These figures show the following: 

criteria pollutants – the major pollutant emitted is NOx, while PM10 is the least emitted pollutant; and 

greenhouse gases – the major pollutant emitted is CO2, while N2O is the least emitted pollutant. 

Combustion-intensive operations such as platform operations, well drilling, and service-vessel 

activities contribute mostly NOx and CO2; platform operations are also the major contributors of VOC 

emissions. As a result of a proposed lease sale, multiple platforms would be installed on the leases, 

and platform construction emissions would contribute appreciable amounts of all pollutants over the 

resulting lease sale’s 50-year analysis period. Emissions from a singular platform construction are 

temporary in nature and generally occur for a period of 3-4 months. Typical construction emissions 

result from the derrick barge placing the jacket and various modular components and from various 

service vessels supporting this operation. Drilling operations contribute considerable amounts of all 

pollutants. These emissions are temporary in nature and typically occur over a 90-day per well 

drilling period. Support vessels for OCS oil- and gas-related activities, as described in Chapter 
Description of the Affected Environment and Impact Analysis 4-29

3.1.4.4, include emissions of NOx, CO, and CO2. These emissions are directly proportional to the 

number and type of OCS operations requiring support activities. Most emissions from these support 

activities occur during transit between the port and offshore facilities; a smaller percentage of the 

emissions occur during idling at the platform.

Currently, there are minor impacts occurring to air quality from drilling and production with 

associated vessel support impacts as shown in the model. Therefore, because the projected 

activities in this scenario for a proposed lease sale are less than the current 2011 GWEI activities, 

the impacts would be minor. The activities’ impacts would vary in intensity based on the type and 

location of the activity.

Flaring and Venting

Reasonably foreseeable flaring and venting emissions operations occur intermittently for 

short periods of time over the life of the lease. Flaring systems are also used to vent natural gas 

during well testing or during repair/installation of production equipment. The BSEE operating 

regulations at 30 CFR § 250.1160 provide for some limited volume, short-duration flaring, or venting 

of some natural gas volumes upon approval by BSEE. These operations may occur for short 

periods of time (typically 2-14 days) as part of unloading/testing operations that are necessary to 

remove potentially damaging completion fluids from the wellbore, to provide sufficient reservoir data 

for the operator to evaluate a reservoir and development options, and in emergency situations. The 

potential impacts from these emergency operations are described in the “Accidental Events” chapter 

below and in Chapter 3.2.3. 

Flaring may involve the disposal of sweet gas or sour gas. Sweet gas is natural gas that 

does not contain hydrogen sulfide (H2S), while sour gas is natural gas that does contain H2S. During 

the flaring of gas containing H2S, the gas entering the flare would largely combust to SO2. The 

contribution of flaring sour gas to SO2 is regulated in 30 CFR part 250 subpart K. The SO2 levels 

from reasonably foreseeable flaring are evaluated as part of the postlease plans review process.

Hydrogen sulfide released to the air can come from natural sources such as swamps, bogs, 

and volcanoes. Hydrogen sulfide can also be released from industrial sources such as petroleum 

refineries, natural gas plants, kraft paper mills, manure treatment facilities, waste-water treatment 

facilities, and tanneries. The concentration of H2S occurring naturally in crude oil varies from 

formation to formation and even varies to some degree within the same reservoir. The natural gas in 

deepwater reservoirs has been mainly sweet (i.e., low in sulfur content), but the oil averages 

between 1 and 4 percent sulfur content by weight. By far, most of the documented production of 

sour gas (i.e., high sulfur content) lies within 150 km (93 mi) of the Breton Wilderness Area Class I 

area. The BSEE regulations at 30 CFR § 250.490(f) describe safety precautions for employees 

operating in an H2S area. Hydrogen sulfide is a naturally occurring compound that is formed from 

the breakdown of organic matter in low oxygen environments. The effects of H2S depend on the 

magnitude, duration, and frequency of exposure, as well as the susceptibility of the individual 

organism or environment. The human nose is very sensitive and can detect extremely low levels of 

H2S. A rotten egg odor characterizes H2S at very low concentrations. However, prolonged 
4-30 Gulf of Mexico Multisale EIS

exposure to low levels of H2S can cause skin irritation and olfactory paralysis. Therefore, relying on 

odor or sense of smell would not be a reliable warning signal to detect H2S presence. Short-term 

exposure to high concentrations of H2S can cause death. Portable monitors worn by workers, as 

well as visual and audible alarms and H2S sensors on platforms to activate when the presence of 

H2S is detected, can help to prevent loss of life. According to the NPS, Gulf Islands National 

Seashore visitors have complained about H2S odors. BOEM expects that concentrations at the 

park, resulting from OCS sources of H2S, to be at very low nuisance levels. The source of odors in 

the park may include releases from the local marsh muds or nearby State oil and gas activity. 

Therefore, several contributing factors could be responsible for the odors at Gulf Islands National 

Seashore.

Impacts to air quality from reasonably foreseeable flaring and venting would be minor

because the activity is short in duration during a 50-year analysis period, and release likely 

dissipates before reaching coastal areas due to distance. The impacts would vary in intensity based 

on the type of flare and location of the activity.

Decommissioning

During a 50-year analysis period, most decommissioning occurs during years 20-40. 

Decommissioning emissions are due mainly to engines on vessels used in the decommissioning 

process for propulsion, electrical power, and ancillary mechanical equipment and activities. These 

emissions include the following pollutants: CO, NO2, PM, SO2, CO2, CH4, N2O, and VOCs. There 

are two primary methodologies used in the GOM for cutting decommissioning targets: nonexplosive 

and explosive severance. Nonexplosive methods include abrasive cutters, mechanical cutters, 

diamond wire cutting devices, and cutting facilitated by commercial divers using arc/gas torches. 

Though a relatively slow process and potentially dangerous for offshore workers, nonexplosiveseverance activities have little to no impact on air quality. Explosive-severance activities use 

specialized charges to achieve target severance. Unlike most nonexplosive methods, severance 

charges can be deployed on multiple targets and detonated nearly simultaneously, effecting rapid 

severances. Though a relatively faster yet safer process for offshore workers with the omission of 

diver cutting, the detonation of cutting charges occurs mainly underwater and, therefore, would have 

little impact on air quality. For this reason, impacts to air quality from decommissioning would be 

minor. The impacts would vary in intensity based on the type and location of the activity. The main 

concern of air quality from decommissioning is the exhaust from support equipment. The less time 

that heavy equipment must be employed during decommissioning the less air quality will be 

negatively impacted.

4.1.2.2 Accidental Events

The greatest impact-producing factors associated with a proposed action that could 

potentially affect air quality from a reasonably foreseeable accidental event include (1) emergency 

flaring and venting, and (2) oil spills. Accidental air emissions are described in Chapter 3.2.3. 
Description of the Affected Environment and Impact Analysis 4-31

Emergency Flaring and Venting

Emergency flaring is distinguished from routine flaring by the magnitude, frequency, and 

duration of flaring events. Emergency flaring events are the result of operating conditions that are 

outside normal process and equipment operations. Emergency flaring is generally characterized by 

infrequent occurrence, high-emission rates, and short durations. Potential impacts to air quality are 

not expected to be significant, except in the rare case of a catastrophic event, which is not part of a 

proposed action and not reasonably foreseeable. Emergency flaring may be conducted to manage 

excess natural gas during an accidental event, such as damage to a pipeline that transports the gas 

to shore, or a process upset. In the absence of safety flares, plants would be at a higher risk for fires 

and explosions. The flare is operated temporarily until the emergency situation is resolved. Flaring 

would result in the release of NOx emissions from the flare; SO2 emissions would be dependent on 

the sulfur content of the crude oil; and particulate matter from the flare would affect visibility.

Venting would result in the release of mainly CH4 emissions. Emergency venting may be 

necessary where flaring of the gas is not possible or in situations precluding the use of a flare gas 

system, such as insufficient hydrocarbon content in the gas stream to support combustion or a lack 

of sufficient gas pressure to allow it to enter the flare system. Therefore, the potential impacts of a 

reasonably foreseeable accidental gas release analyzed in this Multisale EIS would be localized and 

short term, and would have no impact to coastal areas, including the Bradwell Bay Wilderness Area, 

Breton Wilderness Area, Chassahowitza National Wilderness Area, Everglades National Park, and 

St. Marks Wilderness Area, or the Padre Island National Seashore and Gulf Islands National 

Seashore. The accidental event’s impacts on air quality over the OCS and adjacent onshore areas 

on accidental gas releases are expected to be minor. 

The accidental release of hydrocarbons related to a proposed lease sale would result in the 

emission of air pollutants. The OCS accidents would include the release of oil, condensate, or 

natural gas or chemicals used offshore or pollutants from the burning of these products. The air 

pollutants include criteria NAAQS pollutants, volatile and semi-volatile organic compounds, hydrogen 

sulfide, and methane. These pollutants are discussed in Chapter 4.1.2 above. These accidental 

events may potentially affect the air quality at the Bradwell Bay Wilderness Area, Breton Wilderness 

Area, Chassahowitza National Wilderness Area, Everglades National Park, and St. Marks 

Wilderness Area, as well as the Padre Island National Seashore and Gulf Islands National 

Seashore, during a 50-year analysis period. 

Emergency flaring may be conducted to manage excess natural gas during an accidental 

event such as damage to a pipeline that transports the gas to shore or a process upset. In the 

absence of safety flares, plants would be at a higher risk for fires and explosions. The flare is 

operated temporarily until the emergency situation is resolved. Flaring would result in the release of 

NOx emissions from the flare; SO2 emissions would be dependent on the sulfur content of the crude 

oil; and particulate matter from the flare would affect visibility.
4-32 Gulf of Mexico Multisale EIS

Oil Spills

Accidental oil spills, though not considered a routine OCS oil- and gas-related activity, have 

the potential to occur during each phase of oil and gas operations. In April 2010, the Deepwater

Horizon explosion and oil spill was a catastrophic event that occurred on the Gulf of Mexico OCS. 

The impacts on air quality from the Deepwater Horizon explosion and oil spill have been well 

documented. BOEM does not expect accidental events to resemble the Deepwater Horizon

explosion and oil spill. BOEM is not analyzing the rare, catastrophic Deepwater Horizon explosion 

and oil spill as an accidental event in this chapter but rather is using the information to describe the 

potential impacts common to spills and accidental events regardless of size. Additionally, BOEM 

has assessed the potential impacts resulting from a low-probability catastrophic event, and the 

analysis is presented in the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017). 

To date, air monitoring conducted following the Macondo loss of well control and spill has not found 

any pollutants at levels expected to cause long-term harm (USEPA, 2010). The loss of well control 

and blowouts are rare events and of a short duration. Potential impacts to air quality are not 

expected to be significant, except in the rare case of a catastrophic event, which is not reasonably 

foreseeable and not part of a proposed action. Therefore, potential impacts as a result of the much 

smaller reasonably foreseeable accidental spills analyzed in this Multisale EIS would be localized 

and short term, and would have no impact to coastal areas, including the Bradwell Bay Wilderness 

Area, Breton Wilderness Area, Chassahowitza National Wilderness Area, Everglades National Park, 

and St. Marks Wilderness Area, as well as the Padre Island National Seashore and Gulf Islands 

National Seashore. The accidental event’s impact on air quality over the OCS and adjacent onshore 

areas on oil spills is therefore expected to be minor. 

In the Gulf of Mexico, evaporation from an oil spill would result in concentrations of VOCs in 

the atmosphere, including chemicals that are classified as being hazardous. Benzene, toluene, 

ethylbenzene and xylene (BTEX) are a category of VOCs that occur naturally in crude oil, as well as 

during the process of making of gasoline and other fuels from crude oil. The VOC concentrations 

would occur anywhere where there is an oil slick, but they would be highest at the source of the spill 

because the rate of evaporation depends on the volume of oil present at the surface. The VOC 

concentrations would decrease with distance as the layer of oil gets thinner. The lighter compounds 

of VOCs, such as BTEX, would be most abundant in the immediate vicinity of the spill site. The 

heavier compounds would be emitted over a longer period of time and over a larger area. Some of 

the compounds emitted could be hazardous to workers in close vicinity of the spill site. In hazardous 

conditions, the Occupational Safety and Health Administration and USCG regulations require 

workers to use breathing protection. The hazard to workers can also be reduced by limiting 

exposure through limited work shifts, rotating workers in close vicinity of the spill site, and pointing 

vessels into the wind. While the reasonably foreseeable spills analyzed as part of this Multisale EIS 

are significantly smaller than the catastrophic Deepwater Horizon explosion and oil spill, air samples 

collected during that event by individual offshore workers of British Petroleum (BP), the Occupational 

Safety and Health Administration (OSHA), and the USCG showed levels of BTEX that were mostly 

under detection levels. All samples had concentrations below the OSHA permissible exposure limits 

and the more stringent American Conference of Governmental Industrial Hygienists threshold limit 
Description of the Affected Environment and Impact Analysis 4-33

values (U.S. Dept. of Labor, OSHA, 2010). Therefore, the reasonably foreseeable oil spills would be 

expected to be even smaller.

The VOC emissions that result from the evaporation of oil contribute to the formation of 

particulate matter (PM2.5) in the atmosphere (Brock et al., 2012). In addition, VOCs could cause an 

increase in ozone levels, especially if the release were to occur on a hot, sunny day with sufficient 

concentrations of NOx present in the lower atmosphere. Effects to ozone concentrations would 

depend on distance of the proposed lease sale area from shore and the accidental spill size. If there 

were any effects to onshore ozone concentrations to a state, they would likely be temporary in 

nature and last, at most, the length of time of the spill’s duration.

Removal and containment efforts to respond to an ongoing offshore spill would likely require 

multiple technologies, including source containment, mechanical cleanup, in-situ burning of the slick, 

and chemical dispersants (Chapter 3.2.7). In-situ burning would result in ambient concentrations of 

CO, CO2, NOx, PM10, PM2.5, and SO2 very near the site of the burn and would generate a plume of 

black smoke. The levels of PM2.5 could be a hazard to personnel working in the area, but this could 

be effectively mitigated through monitoring and relocating vessels to avoid areas of highest 

concentrations.

4.1.2.3 Cumulative Impacts

An analysis of the cumulative impacts in the GOM region is described in this chapter. This 

cumulative analysis considers OCS oil- and gas-related and non-OCS oil- and gas-related activities 

that could occur and adversely affect air quality during the 50-year analysis period.

Under BOEM Contract Number M14PC00007, “Air Quality Modeling in the Gulf of Mexico 

Region” study, photochemical grid modeling was conducted to assess the impacts to nearby states 

of existing and proposed future OCS oil and gas exploration, development, and production. 

Preliminary results from the modeling conducted for this study have become available and are being 

included in this Multisale EIS to disclose potential cumulative and incremental air quality impacts of 

the proposed lease sales. These preliminary results represent the best available science at this time 

and are included in Appendices F-H. At the lease issuance stage, no activities beyond certain 

ancillary activities are actually authorized by the lease; therefore, there are few environmental 

impacts, including air quality, reasonably expected from a proposed lease sale itself (refer to 

Chapter 1.3.1). During postlease activities, BOEM has the authority to disapprove or require 

additional mitigation to reduce impacts from site-specific activities as additional information becomes 

available.

The air quality modeling study examines the potential impacts of the proposed lease sales 

with respect to (1) the NAAQS for the criteria pollutants O3, NO2, SO2, CO, PM2.5, PM10; (2) the 

Class I and Class II PSD increments; and (3) the AQRVs, including visibility and acid deposition 

(sulfur and nitrogen) in the nearby Class I and sensitive Class II areas.
4-34 Gulf of Mexico Multisale EIS

Results of each impact analysis are compared with applicable “thresholds of concern,” which 

have typically been used in air quality impact evaluations by other Federal actions, including onshore 

oil and gas leasing programs. The applicable comparison thresholds for criteria pollutant impacts 

are the corresponding NAAQS. For acid (i.e., sulfur and nitrogen) deposition impacts, thresholds are 

based on (1) incremental impacts considered sufficiently small as to have no consequential effect on 

the receiving ecosystems, i.e., Deposition Analysis Thresholds, and (2) critical load levels above 

which cumulative ecosystem effects are likely to or have been observed. For visibility impacts, 

thresholds are based on incremental changes in light extinction below the level at which they would 

be noticeable to the average human observer. Additional information about these various thresholds 

is provided in relevant chapters in the remainder of this Multisale EIS.

Overview of Modeling Approach

The Comprehensive Air-quality Model with extensions (CAMx) and Community Multiscale Air 

Quality (CMAQ) photochemical grid models were used to simulate the dispersion and chemical 

transformation of pollutants over the study area. Similar to other air quality models, CAMx/CMAQ 

require several input datasets, including meteorology and an emissions inventory. Figure 4-6

presents an overview of how these project datasets fit together for the “Air Quality Modeling in the 

Gulf of Mexico Region” study. Photochemical modeling was conducted for two emission scenarios:

• a Base Case scenario using the 2012 base year (BY) emissions inventory 

described in Appendix G to evaluate model performance and to define current 

baseline air quality conditions; and

• a Future Year development scenario (FY) using an emissions inventory that 

includes potential new sources associated with the lease sales analyzed in this 

Multisale EIS and the projections of emissions to 2017 for all other sources as 

described in Appendix G to estimate the cumulative and incremental air quality

and AQRV impacts of the lease sales analyzed in this Multisale EIS.

NOTE: Both scenarios used the same 2012 meteorological dataset and the same 

photochemical model configuration. (In determining the Base Case (base year) for the “Air Quality

Modeling in the Gulf of Mexico Region” study emissions inventory, 2011 was initially selected based 

on data availability. Calendar year 2011 emissions data are readily available for most sources from 

USEPA’s National Emissions Inventory (USEPA, 2015a) and BOEM’s Year 2011 Gulfwide 

Emissions Inventory Study (Wilson et al., 2014). However, 2011 was an unusually hot and dry year 

in the Gulf of Mexico region, particularly in Texas, which experienced record heat and dry conditions 

during the summer of 2011 and which had a very high incidence of wildfires. Therefore, 2012 was 

selected as the base year as more representative of “typical” conditions in the Gulf of Mexico 

region.)
Description of the Affected Environment and Impact Analysis 4-35

Figure 4-6. Overview of the Gulf of Mexico Region’s Cumulative 

and Visibility Impacts Assessment.

Modeling Input – Meteorological Modeling

Meteorological datasets required to determine the rate that pollutants disperse and react in 

the atmosphere include spatially and temporally varying parameters such as wind speed, wind 

direction, air temperature, and humidity, among others. Sources of meteorological information 

include datasets of measurements gathered at various locations within the Gulf of Mexico region 

domain, i.e., the area of interest where geographic features influence transport patterns. Results of 

these meteorological models provide the inputs needed to exercise the photochemical grid air quality

dispersion models used in the “Air Quality Modeling in the Gulf of Mexico Region” study. For this 

study, the Advanced Research version of the Weather and Research Forecasting (WRF) model, as 

described in Appendix F, was applied over a system of nested modeling grids. Figure 4-8 shows 

the WRF modeling grids at horizontal resolutions of 36, 12, and 4 km. All WRF grids were defined 

on a Lambert Conformal Conic projection centered at 40° N. latitude, 97° W. longitude with true 

latitudes at 33° N. latitude and 45° N. latitude (the “standard RPO” projection). In Figure 4-8, the 

outermost domain (outer box) with 36-km resolution includes the entire continental U.S. and parts of 

Canada and Mexico, and captures synoptic-scale (storm system-scale) structures in the 

atmosphere. The inner 12-km regional grid (d02) covers the southeastern U.S. and is used to 

ensure that large-scale meteorological patterns across the region are adequately represented and to 

provide boundary conditions to the 4-km domain. The 4-km domain (d03) is centered on the coastal 

areas of the southeastern U.S. and over-water portions of the Gulf of Mexico. The 4-km domain 

area, which includes parts of Alabama, Georgia, Louisiana, Mississippi, and Texas, and all of 

Florida, as well as the WPA, CPA, and EPA, and part of the Atlantic Ocean, was the main focus of 

the emissions inventory efforts. However, the focus of this Multisale EIS analysis are the coastal 

areas adjacent to the WPA, CPA, and EPA, which include Texas, Louisiana, Mississippi, Alabama, 

and Florida.
4-36 Gulf of Mexico Multisale EIS

Figure 4-7. Geographic Domain of the “Air Quality Modeling in the Gulf of Mexico” 

Region Study.

Modeling Input – Emissions Inventories

Analysis of the cumulative air quality impacts of this Multisale EIS required the development 

of both a contemporary base year emissions inventory for the base case analysis and a projected 

future year inventory that includes emissions from all cumulative sources, as well as additional 

emissions anticipated to occur under this Multisale EIS’ alternative in which additional exploratory 

drilling and construction of new shallow and deepwater platforms to support oil and gas production 

would occur. Both the base case and future year cumulative source inventories represent 

comprehensive compilations of pollutant emissions from all human activities as well as emissions 

from biogenic and geogenic sources. Specific details on the development of the emission inventory 

are presented in Appendix G. The scope of the air pollutant emissions inventory for the “Air Quality 

Modeling in the Gulf of Mexico Region” study is defined in terms of pollutants, representative time 

periods for the base case and future year analysis, geographical domain, and sources to be 

included.

Pollutants included in the inventories were selected to support analysis of air quality impacts 

in terms of impacts on attainment of the NAAQS and on AQRVs, including acid deposition and 

visibility. The selected pollutants are as follows: the NAAQS criteria pollutants – CO, NOx (which 

includes NO and NO2 and is stated in terms of equivalent mass of NO2), PM2.5, fine plus coarse PM 

(PM10), and SO2; criteria precursors – VOCs (which are precursors to the formation of ozone and 
Description of the Affected Environment and Impact Analysis 4-37

organic particulates) and ammonia (NH3) (which is a precursor to particulate matter formation). As 

previously mentioned in Chapter 4.1.1, lead (Pb) was not included in the inventory. While the 

cumulative air quality impact analysis did not focus specifically on air toxics, the compilation of VOC 

emissions by source type, together with VOC speciation profiles by source type, provides a 

mechanism for estimating emissions of individual air toxic species.

Overview of Modeling Results

The post-processed results for comparison to the NAAQS, PSD increments, and visibility 

and acid deposition thresholds are described below. The results in this section are still preliminary, 

but are being used to disclose the potential cumulative impacts to coastal areas.. Specific 

cumulative impact analysis results from the “Air Quality Modeling in the Gulf of Mexico Region” study 

are presented in Appendix H. 

The CAMx future year scenario model and ozone and particulate matter source 

apportionment modeling outputs were post-processed for comparison against the NAAQS and PSD 

concentration increments, and other thresholds of concern as discussed below. For analyzing the 

NAAQS and AQRV impacts at Class I and sensitive Class II areas, the thresholds of concern used 

were as defined by the Federal Land Manager that manages each Class I/II area.

Source apportionment provides a means of assessing the contributions of specified sources 

or categories of sources to predicted ozone and PM concentrations and their precursors under the 

air quality conditions being simulated. Source contributions were calculated for ozone and PM using 

the Ozone and Particulate Source Apportionment Technology routines included in CAMx. Source 

apportionment analyses were applied to the future year scenario in order to analyze the pre- and 

postlease OCS oil- and gas-related impacts to short-term and annual NAAQS, AQRVs, and PSD 

increments. While BOEM selected nine source categories for the CAMx future year source 

apportionment simulation as listed in Table 4-4, only four are appropriate for this Multisale EIS 

analysis because they apply to the Gulf of Mexico region.

Table 4-4. Source Categories for Source Apportionment Calculations.

Category ID Sources

SC3 Additional BOEM OCS oil and gas production platforms associated with 

this Multisale EIS (with Action)

SC4 Additional BOEM oil and gas production support vessels and helicopters 

associated with this Multisale EIS (with Action)

SC5 BOEM OCS oil and gas production platforms, support vessels, and 

helicopters under the base case (No Action)

SC6 All other marine vessel activity in the Gulf of Mexico not associated with 

OCS oil and gas development, exploration, or production

SC = source category.
4-38 Gulf of Mexico Multisale EIS

4.1.2.3.1 Impacts Assessment

NAAQS Impacts

The impacts for the NAAQS criteria pollutants ozone (O3), nitrogen dioxide (NO2), sulfur 

dioxide (SO2), carbon monoxide (CO), fine particulate matter with aerodynamic diameter less than 

2.5 μm (PM2.5), and fine plus coarse particulate matter with aerodynamic diameters less than 10 μm 

(PM10) are discussed below.

Comparison to the NAAQS

Results of each impact analysis are compared with applicable “thresholds of concern,” which 

have typically been used in air quality impact evaluations by other Federal actions, including onshore 

oil and gas leasing programs. The applicable comparison thresholds for criteria pollutant impacts 

are the corresponding NAAQS (Table 4-5).

The CAMx future year scenario predicted that the total concentrations from all emission 

sources were post-processed for comparison to the applicable NAAQS in two different ways. First, 

the CAMx predictions were compared directly against each NAAQS. This is referred to as the 

“absolute” prediction comparison. These absolute prediction comparisons may be misleading in 

cases in which the model exhibits significant prediction bias. In recognition of this, USEPA modeling 

guidance (USEPA, 2007 and 2014) recommends using the model in a relative sense when 

projecting future year ozone, PM2.5, and regional haze levels, and USEPA has developed the 

Modeled Attainment Test Software (MATS; Abt., 2014) for making such future year projections. This 

approach uses the ratio of future year to current year modeling results to develop Relative Response 

Factors (RRFs) that are applied to observed current year Design Values (abbreviated as either DVC 

or DVB) to make future year Design Value (DVF) projections (i.e., DVF = DVC x RRF). The MATS 

was applied to the prediction of both ozone and PM2.5 DVFs.

Table 4-5. NAAQS and PSD Increments.

Pollutant Pollutant/Averaging 

Time NAAQS PSD Class I Increment1

PSD Class II 

Increment1

CO 1-hour2 35 ppm

40,000 μg/m3 -- --

CO 8-hour2 9 ppm

10,000 μg/m3 -- --

NO2 1-hour3 100 ppb

188 μg/m3 -- --

NO2 Annual4 53 ppb

100 μg/m3 2.5 μg/m3 25 μg/m3

O3 8-hour5 0.070 ppm

137 μg/m3 -- --

PM10 24-hour6 150 μg/m3 8 μg/m3 30 μg/m3

PM10 Annual7 -- 4 μg/m3 17 μg/m3

PM2.5 24-hour8 35 μg/m3 2 μg/m3 9 μg/m3

PM2.5 Annual9 12 μg/m3 1 μg/m3 4 μg/m3
Description of the Affected Environment and Impact Analysis 4-39

Pollutant Pollutant/Averaging 

Time NAAQS PSD Class I Increment1

PSD Class II 

Increment1

SO2 1-hour10 75 ppb

196 μg/m3

SO2 3-hour11 0.5 ppm

1,300 μg/m3 25 μg/m3 512 μg/m3

SO2 24-hour -- 5 μg/m3 91 μg/m3

SO2 Annual4 -- 2 μg/m3 20 μg/m3

1 The PSD demonstrations serve information purposes only and do not constitute a regulatory 

PSD increment consumption analysis.

2 No more than one exceedance per calendar year.

3 98th percentile, averaged over 3 years.

4 Annual mean not to be exceeded.

5 Fourth-highest daily maximum 8-hour ozone concentrations in a year, averaged over 3 years, 

NAAQS promulgated December 28, 2015.

6 Not to be exceeded more than once per calendar year on average over 3 years.

7 3 year average of the arithmetic means over a calendar year.

8 98th percentile, averaged over 3 years.

9 Annual mean, averaged over 3 years, NAAQS promulgated December 14, 2012.

10 99th percentile of daily maximum 1-hour concentrations in a year, averaged over 3 years.

11 No more than one exceedance per calendar year (secondary NAAQS).

Ozone

The ozone NAAQS is defined as an 8-hour averaging time that is expressed as a 3-year 

average of the 4th highest maximum daily average. Since only one calendar year of modeling results 

are available for the base year and future year outcome, the future year 4th highest maximum daily 

average 8-hour ozone concentration is used as a pseudo-NAAQS comparison metric. The USEPA’s 

Modeled Attainment Test Software was used to make future year ozone future design values 

projections using the CAMx 2012 Base Case and Future Year Scenario modeling results. 

The impacts to air quality from O3 for of all proposed and existing oil and gas emissions from 

Gulf of Mexico OCS sources and their support vessels/aircraft (Source Group C) are moderate

because the future year design values were above the current year design value (which was already 

above the NAAQS). The modeling suggests that the maximum contribution of all proposed and 

existing oil and gas emissions from Gulf of Mexico OCS sources and their support vessels/aircraft 

(Source Group C) occur in Galveston, Texas (a nonattainment area).

The impacts to air quality from O3 for Source Group B (new platforms and associated 

support vessels and aircraft under this Multisale EIS) are minor because the future year design 

values were lower than the current year design values. The modeling suggests that the maximum 

contribution of Source Group B is centered in the GOM offshore of Louisiana; maximum impacts 

from the State seaward boundaries inland along the coast of Cameron Parish, Louisiana. Source 

Group A (new platforms under this Multisale EIS) maximum contributions occur in the same location, 

but the support vessel and helicopter activities (from Source Group B) are responsible for the greater 

impacts landward of the State seaward boundary.
4-40 Gulf of Mexico Multisale EIS

NOTE: For the ozone impacts assessment, please note that the States will not designate 

under the 2015 ozone standard of 70 ppb until 2017, with the earliest attainment date of March 2021 

for marginal areas. For this impacts assessment, the non-OCS source emissions were based on 

USEPA’s 2017 emission projections, with a future modeled year of 2017 and compared with the 

70-ppb standard. This assessment is assuming the standard will be attained in advance of the 

actual attainment date but wanted to give maximum OCS oil and gas impacts under the new 70-ppb 

ozone standard.

Particulate Matter (PM)

PM2.5

There are two PM2.5 NAAQS: one for the 24-hour averaging time that is expressed as a 

3-year average of the annual 98th percentile in a year and an annual average over 3 years. With 

1 year of photochemical grid modeling, the annual 98th percentile would correspond to the 8th highest 

24-hour PM2.5 concentration in a year. As described for the ozone NAAQS analysis, the MATS was 

used to calculate DVFs for the 24-hour and annual PM2.5 NAAQS.

All future year modeled concentrations for 24-hour and annual PM2.5 are below the NAAQS. 

The impacts to air quality from 24-hour PM2.5 and annual PM2.5 are minor because the future year 

design values were lower than the current year design values at all sites except one. While the 

annual PM2.5 current year modeled concentration exceeded the NAAQS in Harris County, Texas, 

the projected future year design value at this location is below the NAAQS.

24-hour PM2.5: All current and future year design values are below the NAAQS, and 

the future year design values are projected to be lower than the current year design 

values at all sites. The modeling suggests that the highest 24-hour PM2.5 impacts 

occur at the State seaward boundary off the coast of Louisiana. There were no 

monitoring sites with the 24-hour PM2.5 in excess of the NAAQS, with future year 

modeling projecting no design value exceedances. The maximum contributions due 

to emissions from all existing and proposed GOM platform and support equipment to 

the 8th highest 24-hour PM2.5 concentrations occurs right on the State seaward 

boundary off the coast of Houma, Louisiana.

Annual Average PM2.5: The modeling suggests that the highest annual PM2.5

impacts occur right at the State seaward boundary off the coast of Louisiana. There 

was one monitoring site with annual PM2.5 design value concentrations above the 

NAAQS (in Harris County (Houston), Texas) but reduced to below the NAAQS in the 

future year. The maximum contribution to annual PM2.5 future design values due to 

emissions from all existing and proposed GOM platform and support equipment 

occurs at the State seaward boundary off the coast of Louisiana.
Description of the Affected Environment and Impact Analysis 4-41

PM10

There is only one PM10 NAAQS: one for the 24-hour averaging time that is expressed as a 

3-year average not to be exceeded more than once per calendar year. With 1 year of photochemical 

grid modeling, the annual 98th percentile will correspond to the 8th highest 24-hour PM2.5

concentration in a year. The impacts to air quality from PM10 are minor because, while there are 

concentrations increases in water farther offshore, no overall standards were exceeded.

24-Hour PM10: The OCS oil- and gas-related impacts for the 24-hour PM10 are 

similar to the 24-hour PM2.5 future year modeling, projecting no future design value 

exceedances. The modeled 2nd highest daily average PM10 concentrations can be 

compared with the 24-hour average PM10 NAAQS for the base and future scenarios 

and the base-future differences. The modeling suggests areas of elevated PM10 are 

evident in urban and port areas and in fire zones along the Gulf Coast of Texas and 

Louisiana (impacts of fires on PM10 are also seen). The PM10 decreases between 

the current and future year are modeled along the Louisiana coast, with increases in 

waters farther offshore associated with new emissions from proposed action sources. 

The maximum contribution of all oil and gas platforms and support vessels and 

helicopters (Source Group C) are below the NAAQS, and the maximum contribution 

of the new platforms and associated support vessels and aircraft under this Multisale 

EIS (Source Group B) are below the NAAQS.

Nitrogen Dioxide (NO2) 

There are two NO2 NAAQS: one for the 1-hour averaging time that is expressed as a 3-year 

average of the annual 98th percentile in a year and an annual average over 3 years. With 1 year of 

photochemical grid modeling, the annual 98th percentile would correspond to the 8th highest 24-hour 

NO2 concentration in a year. Results are included below for both the 1-hour NO2 and the annual 

NO2 averaging times. All modeled concentrations for NO2 are below the NAAQS. The impacts to air 

quality from 1-hour NO2 and annual NO2 are minor because overall, concentrations decrease 

between the base and future year scenarios at most locations. While there was in increase between 

the base and future year scenarios for annual NO2 in Vermilion Parish, Louisiana, the no standards 

were exceeded.

1-hour NO2: All modeled 1-hour NO2 concentrations are below the NAAQS. The 

overall, concentrations decrease between the base and future year scenarios at most 

locations. The modeling suggests that the maximum contributions from new 

platforms and support vessels and helicopters associated with this Multisale EIS 

(Source Group B) are dominated by vessel and possibly helicopter traffic in the port 

areas, most notably in Vermilion Parish, Louisiana; and the maximum combined 

contributions from new and existing platforms and support vessels and helicopters 

(Source Group C) are dominant in the area of the LOOP.
4-42 Gulf of Mexico Multisale EIS

Annual NO2: These results are similar to those for 1-hour NO2. The maximum 

impacts of new and existing platforms and support vessels and helicopters 

associated with this Multisale EIS (Source Group C) showed increases between the 

base and future year scenarios to occur near the entrance to the Freshwater Bayou 

Canal in Vermilion Parish, Louisiana, and somewhat larger increases modeled in the 

Permian Basin of west Texas. However, overall no standards were exceeded.

Sulfur Dioxide (SO2) 

There are two SO2 NAAQS: one for a 1-hour averaging time that is expressed as a 3-year 

average of the annual 99th percentile in a year and a 3-hour average not to be exceeded more than 

once per year. All modeled concentrations for SO2 are below the NAAQS. The impacts to air quality

from 1-hour SO2 and 3-hour SO2 are minor because overall, concentrations decrease between the 

base and future year scenarios at most locations as sources retire or apply control equipment.

1-hour SO2: All modeled values are below the NAAQS. While maximum 

contributions are located from sources in areas with deepwater platforms, 

concentrations decrease in most locations in the future year scenario as sources are 

retired or apply control equipment with projected maximum impacts all below the 

NAAQS. 

3-hour SO2: All modeled values are below the NAAQS. These results are similar to 

those for the 1-hour SO2 described above.

Carbon Monoxide (CO)

There are two CO NAAQS: a 1-hour averaging time and an 8-hour average not to be 

exceeded more than once per year. All modeled concentrations for SO2 are below the NAAQS. The 

impacts to air quality from 1-hour CO2 and 8-hour CO are minor because overall, concentrations 

decrease between the base and future year scenarios at all locations.

1-hour CO: The modeled 1-hour CO design values (based on the annual 2nd highest 

daily maximum 1-hour average) for the base, future, and future-base scenarios show 

all values are below the NAAQS.

8-hour CO: The modeled 8-hour CO design values (based on the annual 2nd highest 

non-overlapping running 8-hour average) for the base, future, and future-base 

scenarios show the maximum predicted 8-hour design value in the future year occurs 

at the entrance to the Freshwater Bayou Canal in Vermilion Parish, Louisiana, but no 

over standard was exceeded.
Description of the Affected Environment and Impact Analysis 4-43

Incremental Impacts of PSD Pollutants with Respect to PSD Class I and Class II Increments

As mentioned in Chapter 4.1.1, the WPA, CPA, and EPA include national parks and Federal 

wilderness areas where air quality and AQRVs (primarily visibility) are protected more stringently 

than under the NAAQS. The Class I areas, compared with Class II areas, have lower PSD 

increments that new sources may not exceed and that are protected against excessive increases in 

several AQRVs, including visibility impairment. Table 4-6 lists those areas that are located along the 

Gulf Coast and, thus, are of greatest interest to this analysis.

The incremental AQ/AQRV contributions associated with emissions from each source group 

listed in Table 4-4 were calculated for the Class I and sensitive Class II areas listed in Table 4-6. 

The selected areas include all Class I and sensitive Class II areas within the 4-km modeling domain 

plus additional Class I areas within the 12-km modeling domain (Bradwell Bay).

The Class I and sensitive Class II increments analyses results are expressed in terms of the 

maximum increment consumption over all Class I and sensitive Class II areas within the 4-km 

modeling domain. Incremental impacts of each Source Group at Class I and sensitive Class II areas 

were calculated for all pollutants for which PSD increments have been set (NO2, SO2, PM10, and 

PM2.5) and are discussed below.

Table 4-6. Class I and Sensitive Class II Areas in Gulf Coast and Nearby States.

Type Name Agency State Modeling Domain

Class I Breton Wilderness Area FWS LA 4 km

Class II Breton National Wildlife Refuge FWS LA 4 km

Class II Gulf Islands National Seashore NPS MS, FL 4 km

Class II Padre Island National Seashore NPS TX 4 km

Class I Bradwell Bay Wilderness Area FS FL 12 km

FS = Forest Service; FWS = Fish and Wildlife Service; NPS = National Park Service.

Comparison at the Class I and Sensitive Class II Areas

The maximum contribution of new oil and gas production sources under this Multisale EIS 

were reported for each Class I and sensitive Class II area and were compared against the PSD 

increments given in Table 4-5. Comparisons of impacts from a proposed action with maximum 

allowed PSD increments are presented here as an evaluation of a “threshold of concern” for 

potentially significant adverse impacts, but they do not represent a regulatory PSD increment 

consumption analysis. (Note: This analysis does not constitute a regulatory PSD increment 

consumption analysis as would be required for major sources subject to the New Source Review 

program requirements of the Clean Air Act. Under the Clean Air Act, a PSD increment consumption 

analysis requires major stationary sources subject to PSD review to demonstrate that emission 
4-44 Gulf of Mexico Multisale EIS

increases from the proposed source, in conjunction with all other emissions increases or reductions 

in the impacted area (typically within 50 km [31 mi]), will not cause or contribute to concentrations of 

air pollutants that exceed PSD increments. The PSD increments have been established for NOx, 

SO2, and PM in Class I and sensitive Class II areas. Actions to be authorized by BOEM under this 

Multisale EIS do not typically constitute major stationary sources and do not typically trigger PSD 

permits or review. However, a comparison of ambient concentrations from an accumulation of new 

oil and gas sources within the entire study area to PSD increments at specific Class I and sensitive

Class II areas is included in this analysis for information purposes. This information is presented to 

aid State agencies in tracking potential minor source increment consumption and to aid Federal 

Land Managers or Tribal governments responsible for protecting air resources in Class I areas).

The CAMx source apportionment results for individual source categories were used to 

evaluate the incremental impacts of each of a set of hierarchical source groups as defined in Table

4-6. Note that Source Group B represents all new direct emissions associated with this Multisale 

EIS, and Source Group C represents these sources in addition to all existing OCS platforms and 

associated support vessel and aircraft activity.

The impacts to Class I areas from contributions of new platforms and its associated support 

vessels and aircraft are minor because proposed activities exceed the 24-hour PM2.5 Class I PSD 

increments by 10 percent at the Breton Wilderness Area, which are a result of support vessels and 

helicopter traffic associated with the activities. The impacts to Class I areas from contributions of all 

activities from past, present, and future lease sales are moderate because proposed activities 

exceed the annual and 24-hour PM2.5, 24-hour PM10, and annual NO2 Class I PSD increments at the 

Breton Wilderness Area.

The impacts to sensitive Class II areas from contributions of all activities as a result of a 

single proposed lease sale are minor because, while maximum increases occur at the Gulf Islands 

National Seashore for all PSD pollutants and averaging times and increases occur for annual NO2 at 

the Breton Wilderness Area, there are no exceedances of the PSD Class II increment. The impacts 

to sensitive Class II areas from contributions of all activities from past, present, and future lease 

sales are moderate because proposed activities exceed the annual 24-hour PM2.5 Class II PSD 

increments at the Gulf Islands National Seashore.

Class I Areas

For all source groups described in Table 4-7, the maximum contributions for all PSD 

pollutants and averaging times occur at the Breton Wilderness Area Class I area. Concentration 

increments from Source Groups A and B are less than the maximum allowed PSD increments for all 

pollutants and averaging times, except for the 24-hour PM2.5 increment from Source Group B at the 

Breton Wilderness Class I area where the maximum impact exceeds the Class I PSD increment. 

The difference in the maximum Source Group A 24-hour average PM2.5 increment and the maximum 

Source Group B 24-hour average PM2.5 indicates that support vessels or helicopter traffic associated 

with new offshore platforms, rather than emissions from the platforms themselves, are largely 
Description of the Affected Environment and Impact Analysis 4-45

responsible for pushing the maximum impact above the Class I PSD increment at Breton Wilderness 

Area. However, when the 24-hour PM2.5 impact from Source Group B is averaged over all grid cells 

covering the Breton Wilderness Class I area, the impact is below the Class PSD increment. The 

maximum impacts from Source Group C exceeds the annual and 24-hour PM2.5, 24-hour PM10, and 

annual NO2 Class I PSD increments at the Breton Wilderness Area.. 

Sensitive Class II Areas

For all source groups described in Table 4-7, the maximum contributions occur at the Gulf 

Islands National Seashore for all PSD pollutants and averaging times except annual NO2, which 

occurs at the Breton Wilderness Area. The cumulative impacts (Source Group C) exceed the annual 

24-hour PM2.5 Class II PSD increments at the Gulf Islands National Seashore.

Table 4-7. Source Group for Incremental Impacts Analysis.

Source 

Group 

Included Source 

Categories Comment

A SC3 New oil and gas platform sources under this Multisale EIS

B SC3, SC4 Add support vessels and aircraft associated with new 

platform sources

C SC3, SC4, SC5 Add oil and gas platforms and associated support vessels 

and aircraft under the No Action Alternative

D SC3, SC4, SC5, SC6 Add all other marine vessel activity in the GOM

AQRV Impacts – Including Visibility and Acid Deposition

While visibility and acid deposition are not directly regulated by BOEM, an analysis of the 

potential impacts is provided below.

Results of each impact analysis are compared with applicable “thresholds of concern,” which 

have typically been used in air quality impact evaluations by other Federal actions, including onshore 

oil and gas leasing programs. The applicable comparison thresholds for visibility impacts are based 

on incremental changes in light extinction below the level at which they would be noticeable to the 

average human observer. The applicable comparison thresholds for acid (i.e., sulfur and nitrogen) 

deposition impacts are based on (1) incremental impacts considered sufficiently small as to have no 

consequential effect on the receiving ecosystems, i.e., Deposition Analysis Thresholds, and 

(2) critical load levels above which cumulative ecosystem effects are likely to or have been 

observed.

Comparison to Visibility and Acid Deposition

Visibility impacts were calculated for each source group using incremental concentrations as 

quantified by the CAMx Particulate Source Apportionment Technology tool. For each source group, 

the estimated visibility degradation at the Class I areas and sensitive Class II areas due to the 

source group are presented in terms of the number of days that exceed a threshold change in 
4-46 Gulf of Mexico Multisale EIS

deciview (∆dv) relative to background conditions. The number of days with a ∆dv greater than 0.5 

and 1.0 are reported.

The preliminary results of impacts of all activities as a result of a single proposed lease sale 

to visibility impairment from a proposed lease sale is expected to be minor to moderate as modeled 

results show exceedances of the visibility thresholds at several of the Class I and sensitive Class II 

areas in the Gulf of Mexico region. The preliminary results of impacts of all activities as a result of all 

contributions of all activities from past, present, and future lease sales to visibility impairment from a 

proposed lease sale is expected to be minor to moderate as modeled results show exceedances of 

the visibility thresholds at several of the Class I and sensitive Class II areas in the Gulf of Mexico 

region.

The preliminary results of impacts of all activities as a result of a single proposed lease sale 

to acid deposition is expected to be minor to moderate as modeled results show incremental 

nitrogen deposition exceeds the western and eastern Deposition Analysis Thresholds at all three 

locations (i.e., the Breton Wilderness Area, Gulf Islands National Seashore, and Padre Island 

National Seashore). Additionally, incremental sulfur deposition is below the Deposition Analysis 

Thresholds in all cases except the sulfur deposition at the Breton Wilderness Area and Gulf Islands 

National Seashore, which exceed the western Deposition Analysis Thresholds but not the eastern 

Deposition Analysis Thresholds.

The preliminary results of impacts of all from contributions of all activities from past, present, 

and future lease sales to acid deposition is expected to be minor to moderate as modeled results 

show cumulative maximum nitrogen deposition to continue exceeding the critical load thresholds 

under the future year scenario for all areas except the Padre Island National Seashore. Additionally, 

cumulative sulfur deposition values are lower, and larger sulfur emission reductions help to reduce 

sulfur deposition from above the critical load to below the critical load at the Breton Wilderness Area 

and Breton National Wildlife Refuge (based on maximum grid cell values). Nevertheless, the 

maximum grid cell sulfur deposition still exceeds the critical load at the Gulf Islands National 

Seashore by a small margin.

Visibility

For visibility impacts, thresholds are based on incremental changes in light extinction below 

the level at which they would be noticeable to the average human observer. Incremental visibility 

impacts were calculated for each source group, as well as the cumulative impact of all sources 

combined. The changes in light extinction from CAMx model concentration increments due to 

emissions from each source group were calculated for each day at grid cells that intersect Class I 

and sensitive Class II areas within the 12/4km modeling domain-km (7/2-mi) modeling domain. For 

Source Group A, the annual 8th highest change in deciview (∆dv) exceed the 1.0 threshold at the 

Breton Wilderness Area, Breton National Wildlife Refuge, and Gulf Islands National Seashore. 

Incremental impacts for Source Group B are larger and include days with the 8th highest change in 

deciview greater than 1.0 at the Padre Island National Seashore in addition to the areas mentioned 
Description of the Affected Environment and Impact Analysis 4-47

above, as well as values greater than 0.5 at the Chassahowitzka Wilderness Area and St. Marks 

National Wildlife Refuge. For Source Group A, the annual 8th highest deciview exceed the 

1.0 threshold at the Breton Wilderness Area, Breton National Wildlife Refuge, and Gulf Islands 

National Seashore. Incremental impacts for Source Group B are larger and include days with 

8th highest deciview greater than 1.0 at Padre Island National Seashore in addition to the areas 

mentioned above as well as values greater than 0.5 at Chassahowitzka Wilderness Area and 

St. Marks National Wildlife Refuge.

Acid Deposition

The CAMx-predicted that wet and dry fluxes of sulfur- and nitrogen-containing species were 

processed to estimate total annual sulfur (S) and nitrogen (N) deposition values at each Class I and 

sensitive Class II area. The maximum annual S and N deposition values from any grid cell that 

intersects a Class I receptor area was used to represent deposition for that area, in addition to the 

average annual deposition values of all grid cells that represent a Class I receptor area. Although 

the convention in the past has been to report just the maximum deposition in any receptor in a Class 

I/II area, since deposition relates to the total amount deposited across an entire watershed, the 

average metric may be considered a more relevant parameter for evaluating potential environmental 

effects. Maximum and average predicted S and N deposition impacts are reported separately for 

each source group.

As a screening analysis, incremental deposition values in Class I and II areas for combined 

Source Groups A (new platforms associated with the highest emissions year of the 10 proposed 

lease sales) and B (new platforms and associated support vessels and helicopters associated with 

the 10 proposed lease sales) were compared to the eastern and western U.S. Deposition Analysis 

Thresholds. Comparison of deposition impacts from cumulative sources to the Deposition Analysis 

Thresholds is not appropriate. Deposition results were also obtained for all other sensitive areas 

throughout the 12-km (7-mi) modeling domain, but the highest deposition values all occurred within 

the 4-km (2-mi) domain. The dividing line between the eastern and western Deposition Analysis 

Thresholds specified in the FLAG guidance is the Mississippi River, which makes sense for most 

locations in the U.S.; however, it is not necessarily clear which Deposition Analysis Threshold would 

be most appropriate for coastal locations along the Gulf Coast, so results are compared here against 

both Deposition Analysis Thresholds. 

Incremental nitrogen deposition exceeds the western and eastern Deposition Analysis 

Thresholds at all three locations (i.e., the Breton Wilderness Area, Gulf Islands National Seashore, 

and Padre Island National Seashore). Incremental sulfur deposition is below the Deposition 

Analysis Thresholds in all cases except the sulfur deposition from Source Group B at the Breton 

Wilderness Area and Gulf Islands National Seashore, which exceeds the western Deposition 

Analysis Thresholds but not the eastern Deposition Analysis Thresholds.

Cumulative nitrogen deposition from all sources combined for the base case and future year 

scenarios were compared against applicable critical load levels in each Class I and II area for which 
4-48 Gulf of Mexico Multisale EIS

critical loads were identified. Cumulative nitrogen deposition is projected to decrease in all areas 

between the 2012 base case and the 2017 future year, which is consistent with an overall reduction 

in NOx emissions. Nevertheless, maximum nitrogen deposition is modeled to continue exceeding 

the critical load thresholds under the future year scenario for all areas except the Padre Island 

National Seashore. Sulfur deposition values are lower, and larger sulfur emission reductions help to 

reduce sulfur deposition from above the critical load to below the critical load at the Breton 

Wilderness Area and Breton National Wildlife Refuge (based on maximum grid cell values). 

Nevertheless, the maximum grid cell sulfur deposition still exceeds the critical load at the Gulf 

Islands National Seashore by a small margin.

OCS Oil- and Gas-Related Impacts

This section includes all activities (i.e., routine activities projected to occur and accidental 

events that could occur) from past, proposed, and future lease sales. Emissions contributing to air 

quality degradation come from many sources. Air pollutants on the NAAQS list are commonly 

referred to as criteria pollutants because they are ubiquitous. Although these pollutants occur 

naturally, elevated levels are usually the result of anthropogenic activities. The OCS oil- and gasrelated activities that could impact air quality include the following: platform construction and 

emplacement; platform operations; drilling activities; flaring; service-vessel trips; fugitive emissions; 

the release of oil, condensate, natural gas, and chemicals used offshore, or pollutants from the 

burning of these products; and a low-probability catastrophic spill, which is not part of the proposed 

action and not likely expected to occur. Based on the air quality modeling results from the “Air 

Quality Modeling in the Gulf of Mexico Region” study, cumulative impacts would be moderate

because, while there are exceedances to the thresholds of concern, the impacts are just enough to 

push over the standard.

In the air quality modeling study, Source Group C represents all proposed (new) and existing 

oil- and gas-related emissions from Gulf of Mexico OCS sources and their support vessels/aircraft. 

According to the modeling results, the impacts of criteria pollutants from Source Group C to air 

quality are below the NAAQS for all pollutants, except ozone which shows an increase in the future 

year design values occurring in Galveston, Texas, which is a nonattainment area. At the Galveston, 

Texas, monitor, the contribution of Source Group A (new platforms) alone was sufficient to bump the 

future year design value from just below the NAAQS to just above the NAAQS (recall comparisons 

to the 70-ppb NAAQS are made after truncating design values to the nearest ppb).

According to the modeling results, the incremental impacts of PSD pollutants from Source 

Group C to the Class I area exceed the annual and 24-hour PM2.5, 24-hour PM10, and annual NO2

Class I PSD increments at the Breton Wilderness Area. The incremental impacts of PSD pollutants 

from Source Group C to the sensitive Class II area exceed the annual 24-hour PM2.5 Class II PSD 

increments at the Gulf Islands National Seashore.
Description of the Affected Environment and Impact Analysis 4-49

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related impacts include other past, present, and reasonably 

foreseeable future activities occurring within the same geographic range and within the same 

timeframes as a proposed action, but they are not related to the OCS Oil and Gas Program. 

Onshore emission sources from non-OCS oil- and gas-related activities include power generation, 

industrial processing, manufacturing, refineries, commercial and home heating, and motor vehicles 

(Chapter 3.3.2.6). The total impact from the combined onshore and offshore emissions would have 

an effect on the ozone nonattainment areas in southeast Texas and the parishes near Baton Rouge, 

Louisiana.

State oil and gas programs (Chapter 3.3.2.1) onshore, in territorial seas, and in coastal 

waters also generate emissions that affect the air quality of any state. These emissions are 

regulated by State agencies and/or the USEPA. Reductions in emissions have been achieved 

through the use of low sulfur fuels, catalytic reduction, and other efforts and, as a result, constitute 

minor impacts to the air quality of any state.

Other major factors influencing offshore environments, such as sand borrowing (Chapter 

3.3.2.7.6), commercial transportation (Chapter 3.3.2.3), military vessels, and recreational vessels 

also generate emissions that can affect air quality. These emissions are regulated by State 

agencies and/or the USEPA. Reductions have been achieved through the use of low sulfur fuels 

and catalytic reduction and, as a result, constitute slight impacts to onshore air quality.

Hurricanes (Chapter 3.3.2.10.2) mainly cause damage to offshore infrastructures and 

pipelines, which may result in an oil spill. A hurricane would cause minor effects on the onshore air 

quality since air emissions in the event of a hurricane are temporary sources. For the cumulative 

scenario, the emissions from oil spill and the associated response activities and infrastructure repair 

activities are expected to be the same as a proposed lease sale and to have lesser effects on the 

onshore air quality.

Additionally, recent information shows that intercontinental dust transport may have impacts 

on the GOM’s air quality. For example, dust from Central America and North Africa has been found 

in the Texas atmosphere. Fine particulates (PM2.5), such as ammonium sulfate, can be suspended 

in the atmosphere and can impair visibility and adversely affect human health. Once in the 

atmosphere, these fine particulates can be transported for long distances. It has been observed that 

a substantial amount of the fine particulates observed in Texas comes from Mexico and Central 

America, and enters into the United States across Texas’ southern border. As a result, it reduces 

the visibility at Big Bend and Guadalupe Mountains National Parks, both Class I (pristine with 

respect to visibility) areas. The results of air dispersion modeling indicate that as much as half of the 

visibility impairment (occurring on 20% of the most visibility impaired days) at Big Bend comes from 

international transport (State of Texas, Commission on Environmental Quality, 2014). The transAtlantic transport of North African dust by summertime trade winds occasionally increases ambient 

particulate matter (PM) concentrations in Texas above air quality standards (Bozlaker et al., 2013). 
4-50 Gulf of Mexico Multisale EIS

These results indicate that an increase in visibility impairment in Texas is likely due to transport of 

dust rather than OCS oil- and gas-related emission sources.

The activities associated with a proposed action would increase global greenhouse gas 

(GHG) emissions from the use of vessels, drilling equipment, and other activities that burn fossil 

fuels. In addition, methane (CH4,) also known as natural gas, is removed from wells and brought 

onto OCS oil- and gas-related facilities along with oil being produced. Sometimes CH4 is released 

as a fugitive gas that can escape unintentionally from leaks in equipment used by operators. As a 

result of exploration, development, and production of oil and gas on the OCS, the activities 

associated with a proposed action are expected to release GHGs and black carbon from the use of 

combustion engines in vessels, construction, drilling, and other equipment, as well as through 

deliberate or accidental release of CH4. In addition to the direct emissions from OCS oil and gas 

operations presented above, BOEM has evaluated GHG emissions covering the lifecycle of OCS oil 

and gas production and consumption. This includes both the “downstream” consumption and 

onshore processing of oil and gas products, as well as the “upstream” emissions from offshore 

exploration, development, and production. This Multisale EIS tiers from the Five-Year Program EIS. 

In the Five-Year Program EIS, the potential impacts of the Program’s activities on climate change 

were assessed in Chapter 4.2.1 (Climate Change) and specifically addressed the GOM proposed 

lease sales in that analysis (Five-Year Program EIS) (USDOI, BOEM, 2016b).

Incremental Contribution of a Single Proposed Lease Sale to Overall Cumulative Impacts

In the air quality modeling study, incremental contributions are categorized as the impacts of 

pollutants from new platforms and their associated support vessels and aircraft. The forecasted data 

used to support modeling analyses include emissions resulting from the 10 proposed lease sales 

annualized by using BOEM’s Resource Evaluation’s mid-case scenario. To understand how these 

results would apply to a single proposed lease sale, the level of projected activity was compared 

between the modeled highest year of the 10 proposed lease sales to a single proposed lease sale. 

A regionwide lease sale has not previously been analyzed, and historic trend data are limited. In the 

scenario in Chapter 3.1, the projected activities of a single regionwide lease sale is based on a 

range of historic observations and provides a reasonable expectation of oil and gas production 

anticipated from a single proposed lease sale. The projected activities of 10 proposed regionwide 

lease sales’ mid-case scenario, which was used in the model, falls within the range of a single 

proposed lease sale. This is conservative because the current price of oil equals the low range of 

the scenario. Using these assumptions, the potential impacts of a single proposed lease sale would 

be minor because the affected resource could be avoided with proper mitigation. The modeling 

results show that ozone exceeds the NAAQS in Galveston, Texas, and 24-hour PM2.5 exceeds the 

Class I PSD increment at the Breton Wilderness Area. The impacts were sufficient to increase the 

future year design value from just below the NAAQS for ozone and over the Class I PSD increment, 

respectively.

In the air quality modeling study, Source Group B represents new platforms and emissions 

and their support vessels and aircraft. According to the modeling results, the impacts of criteria 
Description of the Affected Environment and Impact Analysis 4-51

pollutants from Source Group B to air quality are below the NAAQS for all pollutants, except for 

ozone. At the Galveston, Texas, monitor, the contribution of Source Group A (new platforms) alone 

was sufficient to bump the future year design value from just below the NAAQS to just above the 

NAAQS.

The impacts to Class I areas from contributions of new platforms and their associated 

support vessels and aircraft show that proposed activities exceed the 24-hour PM2.5 Class I PSD 

increments by 10 percent at the Breton Wilderness Area, which are a result of support vessels and 

helicopter traffic associated with the activities.

The impacts to sensitive Class II areas from contributions of all activities as a result of a 

single proposed lease sale are minor because, while maximum increases occur at the Gulf Islands 

National Seashore for all PSD pollutants and averaging times and increases occur for annual NO2 at 

the Breton Wilderness Area, there are no exceedance of the PSD Class II increment.

4.1.2.4 Incomplete or Unavailable Information

This chapter discusses the incomplete or unavailable information needed to assess the 

impacts from OCS oil- and gas-related activities. Relevant final air modeling study results are 

unavailable at this time. However, BOEM has used preliminary results, which are provided in 

Appendices F-H in its place. These preliminary results were incorporated into the analysis and is 

the best science available. Furthermore, BOEM relied on data gathered from recent Gulf of Mexico 

OCS emission inventories, along with scenarios or estimates of future production. The scenarios 

provide (1) the assumptions for and estimates of future activities, (2) the rationale for the scenario 

assumptions and estimates, and (3) the type, frequency, and quantity of emissions from offshore 

sources associated with a proposed lease sale. Finally, emissions as a result of a proposed lease 

sale would be regulated at the postlease stage under air quality plan reviews. Additional monitoring 

measures and air quality dispersion modeling can be requested of the operator if a further analysis is 

needed and mitigation would be required as necessary.

BOEM determined the projected total emissions that would result from the activities on a 

lease based on estimated emissions from various OCS non-platform and OCS platform equipment 

types, such as diesel engines and generators, and the level of offshore activity projected in 

Chapter 3.1. These same emissions estimates were used as inputs for modeling scenarios to 

predict future impacts. The final study results are not available in time for this Multisale EIS, but 

BOEM expects that they would be included in future EIS documents. To address data gaps and 

current impacts, BOEM used the preliminary results, emissions inventory data, available studies, 

postlease plan information, and current proposed lease sale scenario data, as well as previous 

proposed action scenario data, to reach the impact conclusions.

The air quality in the GOM can be affected by the pollution emitted from OCS oil- and 

gas-related sources as well as non-OCS oil- and gas-related sources. These pollution sources can 

also emit a wide variety of pollutants. To improve air quality and reduce air pollution, the Clean Air 
4-52 Gulf of Mexico Multisale EIS

Act Amendments set regulatory limits on pollutants that help to ensure basic health and 

environmental protection from air pollution. To assess the amount of pollution being emitted, 

pollutants have to be measured. To determine impacts from these pollutants, emission-related 

conditions (e.g., rate of emission, height, and distance of sources from coastline) and environmental 

conditions (e.g., wind speed and direction, humidity, temperature, and height of the atmospheric 

surface layer where pollutants are transported) are calculated.

Emissions from activities related to prior lease sales are represented by the 2011 GWEI 

database. Emissions from BOEM’s proposed lease sales are estimated from the exploration and 

development scenario and have been included in the emission inventory that will be used in the 

model to determine routine impacts. The “Air Quality Modeling in the Gulf of Mexico Region” study 

includes development of meteorological datasets appropriate for air quality modeling of the study 

area (which includes a proposed lease sale), comprehensive emissions inventory of all sources in 

the GOM region, and air quality modeling for the cumulative impacts and visibility assessment. 

Given that BOEM does not have the final results from the ongoing air quality modeling study yet, for 

this Multisale EIS, BOEM relied on emissions inventory data, available studies on OCS oil- and gasrelated activities, postlease exploration and development plan information, and the preliminary 

modeling results to fill data gaps. This approach was adequate because it assessed a combination 

of pollutants from OCS oil- and gas-related activities, non-OCS oil- and gas-related activities, and 

non-oil and gas activities.

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

As mentioned in Chapter 3, for a proposed lease sale under Alternative A, BOEM projects 

that no more activity would occur than has resulted in the past from the highest CPA lease sale 

combined with the highest WPA lease sale. The contribution of routine and accidental events of a 

proposed lease sale to air quality would result in minor impacts because most impacts on the 

affected resource could be avoided with proper mitigation. The emission sources would not produce 

emissions sufficient to overwhelm the effects of wind and transport in a single area, causing 

deterioration of air quality over the regionwide OCS. The incremental contribution of a single 

regionwide proposed lease sale would likely have a minor impact on coastal areas because most 

impacts on the affected resource could be avoided with proper mitigation. The support vessels and 

aircraft associated with new platforms is a lead contributor to the increased impacts in the area.

4.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Since this Alternative excludes the available unleased blocks in the WPA, it would result in 

activity concentrated in the CPA/EPA. As mentioned in Chapter 3, for a proposed lease sale under 

Alternative A, BOEM projects that no more activity would occur than has resulted in the past from 

the highest CPA lease sale combined with the highest WPA lease sale. Therefore, the impacts to 

Alternative B would be very similar to Alternative A. The incremental contribution of a single 

CPA/EPA proposed lease sale would likely have a minor impact on coastal nonattainment areas 

because most impacts on the affected resource could be avoided with proper mitigation. 
Description of the Affected Environment and Impact Analysis 4-53

Water quality is a term used to 

describe the condition or 

environmental health of a 

waterbody or resource, 

reflecting its particular 

biological, chemical, and 

physical characteristics and 

the ability of the waterbody to 

maintain the ecosystems it 

supports and influences. It is 

an important measure for both 

ecological and human health.

4.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Since this Alternative excludes the available unleased blocks in the CPA/EPA, it would result 

in activity concentrated in the WPA. As mentioned in Chapter 3, a maximum of 13 percent of the oil 

production and associated activity and 19 percent of the gas production and associated activity 

would occur in the WPA. While the WPA is a smaller area with less projected activity than is 

proposed for the CPA/EPA under Alterative B, the smaller area could decrease impacts to 

communities from production platforms and also increase total emissions due to travel distances for 

marine vessels; the potential impacts would remain minor. The incremental contribution of a single 

WPA proposed lease sale would likely have a minor impact on coastal areas because most impacts 

on the affected resource could be avoided with proper mitigation. 

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

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

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D would have the same analysis and potential impacts as Alternative A, B, or C 

because there are so few unleased blocks subject to the Topographic Features, Live Bottom

(Pinnacle Trend), and Blocks South of Baldwin County, Alabama, Stipulations. The difference 

between Alternatives A, B, and C with and without any combination of these stipulations is minor for 

air quality. The impacts under Alternative D would not be much different and likely not even 

measurable when compared with the other alternatives.

4.1.2.9 Alternative E—No Action

BOEM has concluded in Chapter 2.3 that the selection of Alternative E would result in no 

additional discernible impacts to the resources analyzed. Cumulative impacts of current and past 

activities, however, would continue to occur under this alternative.

4.2 WATER QUALITY

For the purposes of this analysis, the GOM is divided 

into coastal and offshore waters. Coastal waters are defined to 

include all bays and estuaries from the Rio Grande River to 

Florida Bay. Offshore waters are defined to include those 

waters extending from outside the barrier islands to the 

Exclusive Economic Zone, located within State waters and the 

Federal OCS. The inland extent is defined by the CZMA. For 

the purposes of this chapter, offshore waters are divided into 

three regions: the continental shelf west of the Mississippi River; 

the continental shelf east of the Mississippi River; and deep 

water (>1,000 ft; 305 m).
4-54 Gulf of Mexico Multisale EIS

Coastal water impacts associated with routine activities include increases in turbidity 

resulting from pipeline installation and navigational canal maintenance, discharges of bilge and 

ballast water from support vessels, and runoff from shore-based facilities. Offshore water impacts 

associated with routine activities result from discharge of drilling muds and cuttings, produced water, 

and residual chemicals used during workovers. The discharge of drilling muds and cuttings causes 

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

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

Structure installation and removal and pipeline placement disturb the sediments and cause 

increased turbidity. In addition, offshore water impacts result from supply and service-vessel bilge 

and ballast water discharges.

The activity associated with a proposed lease sale could contribute a small percentage of 

activity in addition to existing and future OCS oil- and gas-related activities. The specific discharges, 

drill muds, cuttings and produced water, and accidents resulting in spills would occur in proportion to 

production and, therefore, would add a small increase to the currently anticipated impacts. 

Furthermore, the vessel traffic and related discharges associated with a proposed lease sale are a 

fraction of the current ongoing commercial shipping and military activity in the Gulf of Mexico. The 

impact of discharges, sediment disturbances, and accidental releases are a small percentage of the 

current overall activity and the overall impacts to coastal and offshore waters. These OCS oil- and 

gas-related sources are related to the activities listed in Table 4-8 below. This table also illustrates 

the impact-level conclusions for each impact-producing factor reached in this chapter’s impact 

analysis.

Table 4-8. Water Quality Impact-Producing Factors That Are Reasonably Foreseeable.

Water Quality Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Geological Sampling Negligible Negligible Negligible Negligible None

Bottom Area 

Disturbance Negligible Negligible Negligible Negligible None

Operational 

Discharges and 

Wastes

Negligible to Negligible to Negligible to Negligible to None

Moderate Moderate Moderate Moderate

Pipeline Installation Negligible Negligible Negligible Negligible None

Decommissioning

and Removal 

Operations

Negligible Negligible Negligible Negligible

None

Accidental Impacts

Drilling Fluid Spills Minor Minor Minor Minor None

Chemical and Waste 

Spills Minor Minor Minor Minor None
Description of the Affected Environment and Impact Analysis 4-55

Water Quality Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Oil Spills

 Without Mitigation Moderate Moderate Moderate Moderate None

 With Mitigation Moderate Moderate Moderate Moderate None

Cumulative Impacts

Incremental 

Contribution2 Negligible Negligible Negligible Negligible None

OCS Oil and Gas3 Negligible

Non-OCS Oil and 

Gas4 Negligible

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This impact level is the incremental contribution of a single proposed lease sale to all cumulative 

impacts in the GOM.

3 This impact level is the cumulative impacts of all past, present, and reasonably foreseeable OCS 

oil- and gas-related activities in the GOM.

4 This impact level is the cumulative impacts of all past, present, and reasonably foreseeable activities in 

the GOM.

Impact-Level Definitions

For the purpose of the following discussion, the significance of impact-producing factors on 

water quality is discussed below. The criteria for significance reflect consideration of the context and 

intensity of impact (40 CFR § 1508.27), based on four parameters: detectability (i.e., measurable or 

detectable impact); duration (i.e., short term, long term); spatial extent (i.e., localized, extensive); 

and severity (i.e., severe, less than severe). For water quality, the significance criteria have been 

broadly defined as follows:

• Negligible – Impacts are defined as short-term (less than 1 year), localized 

contaminants and turbidity that present little to no detectable impact.

• Minor – Impacts are defined as detectable, short-term, localized, or extensive 

but less than severe; however, detectable contaminant concentrations may 

exceed regulatory levels. Minor impacts may have little to no effect on marine 

life.

• Moderate – Impacts are defined as detectable, short term, extensive, and 

severe; or impacts are detectable, short term or long term, localized and severe; 

or impacts are detectable, long term, extensive, or localized but less than severe. 

Moderate impacts may result in acute or chronic effects to marine life.

• Major – Impacts are defined as detectable, short term or long term, extensive, 

and severe; however, major impacts may result in acute or chronic effects to 

marine life and may potentially cause human health effects.
4-56 Gulf of Mexico Multisale EIS

4.2.1 Description of the Affected Environment

The U.S. portion of the GOM follows the coastline of five states, from the southern tip of 

Texas moving eastward through Louisiana, Mississippi, Alabama, and ending in the Florida Keys. 

Including the shorelines of all barrier islands, wetlands, inland bays, and inland bodies of water, the 

combined coastlines of these states total over 75,639 km (47,000 mi) (USDOC, NOAA, 2008a). The 

GOM coastal areas comprise over 750 bays, estuaries, and sub-estuary systems that are associated 

with larger estuaries (USEPA, 2012b). More than 60 percent of U.S. drainage, including outlets from 

33 major river systems and 207 estuaries, flows into the GOM (USEPA, 2014c) and has a large 

influence on water quality. The largest contributing inputs from the U.S coast are from the 

Mississippi and Atchafalaya Rivers in Louisiana. Additional freshwater inputs into the GOM originate 

in Mexico, the Yucatán Peninsula, and Cuba.

The physical oceanography of the deep GOM (>1,000 m; 3,281 ft) can be approximated as a 

two-layer system with an upper layer about 800- to 1,000-m (2,625- to 3,281-ft) deep that is 

dominated by the Loop Current and associated clockwise (anticyclonic) eddies (Welsh et al., 2009; 

Inoue et al., 2008); and the lower layer below ~1,000 m (3,281 ft) that has near uniform currents 

(Welsh et al., 2009; Inoue et al., 2008). Deep waters east of the Mississippi River are affected by 

the Loop Current and associated warm-core anticyclonic eddies, which consist of clear, low-nutrient 

water (Muller-Karger et al., 2001). Cold-core cyclonic eddies also form at the edge of the Loop 

Current and are associated with upwelling and nutrient-rich, high-productivity waters. More details 

on the physical oceanography of the Gulf of Mexico are available in Chapter 3.3.2.9.1. 

The primary factors influencing coastal and offshore environments are temperature, salinity, 

dissolved oxygen, chlorophyll content, nutrients, potential of hydrogen (pH), oxidation reduction 

potential (Eh), pathogens, transparency (i.e., water clarity, turbidity, or suspended matter), and 

contaminant concentrations (e.g., heavy metals, hydrocarbons, and other organic compounds).

Surface water temperatures in the Gulf of Mexico vary seasonally from about 29 oC (84 oF) in 

the summer to about 19 oC (65 oF) in the winter (Gore, 1992). In the summer, warm water may be 

found from the surface down to a thermocline at depths to about 160 ft (50 m). Minimum water 

temperatures below the 5,000-ft (1,524-m) water depth approach 4o C (39 oF) (Forrest et al., 2007).

The salinity at the sea surface in the offshore Gulf of Mexico is generally 36 parts per 

thousand (ppt) (Gore, 1992). Lower salinities are characteristic nearshore where fresh water from 

the rivers mixes with shallow Gulf waters. For example, salinity in open water near the coast may 

vary between 29 and 32 ppt during fall and winter, but it may decline to 20 ppt during spring and 

summer due to increased runoff (USDOI, MMS, 2000b).

There is a surface turbidity layer associated with the freshwater plumes from the Mississippi 

and Atchafalaya Rivers due to suspended sediment in river discharge, especially during seasonal 

periods of heavy precipitation. High turbidity may extend up to 50 mi (80 km) offshore the 
Description of the Affected Environment and Impact Analysis 4-57

Mississippi River and lesser distances to the east and west along the coast. Outside of these areas, 

water clarity in the Gulf of Mexico improves, with low levels of suspended sediment.

During summer months, shelf stratification results in a large hypoxic zone on the LouisianaTexas shelf in bottom waters (Turner et al., 2012; Obenour et. al., 2013). Hypoxia, the condition of 

having low dissolved oxygen concentration in the water (below 2 mg/L), is caused by excessive 

nutrients and other oxygen-demanding contaminants (refer to Chapter 3.3.2.12). Hypoxia often 

forms when the water column becomes vertically stratified and mixing between oxygenated surface 

waters and bottom waters cannot occur. Hypoxia is a widespread phenomenon on the continental 

shelf of the northern GOM and is the largest hypoxic zone in the western Atlantic Ocean (Rabalais 

and Turner, 2001). The hypoxic zone in the GOM occurs seasonally and is influenced by the timing 

of the Mississippi and Atchafalaya River discharge. Formation of the zone is attributed to nutrient 

influxes and shelf stratification, and the zone persists until wind-driven circulation mixes the water 

column. Recent estimates of the area of low oxygen by NOAA (USDOC, NOAA, 2015h) as of 

August 3, 2015, measured 6,474 mi

2 (16,760 km2

) (Figure 3-20), an increase from the size 

measured in 2014 (5,052 mi2

; 13,085 km2) and larger than the estimated size (5,838 mi2; 

15,120 km2

) forecast by LUMCON (2015) in June 2015. These are the most recent data available, 

as a planned cruise to collect data in Summer 2016 was cancelled due to ship mechanical issues 

(USDOC, NOAA, 2016a). The size of the hypoxic zone has been shown to be directly correlated 

with the flux of nitrogen from the Mississippi River (Turner et al., 2012).

Anthropogenic factors that affect coastal water quality include urban runoff and eroded soil 

carrying oil and trace metals, agricultural runoff carrying fertilizer (e.g., nutrients including nitrogen 

and phosphorus), pesticides, fungicides, and herbicides; upstream withdrawals of water for 

agricultural, industrial, and domestic purposes; contamination by industrial and sewage discharges, 

dumping, atmospheric fallout, and spills of oil, chemicals, and hazardous materials (refer to Chapter 

3.3.2.3). Mixing or circulation of coastal water can either improve water quality through flushing or 

be the source of factors contributing to its decline.

Oil and grease and other contaminants associated with the suspended load from rivers may 

ultimately reside in the sediments rather than in the water column. For example, a contaminant may 

react with the mineral particles in the sediment and be removed from the water column (e.g., 

sorption). Thus, under appropriate conditions, sediments can serve as sinks for contaminants such 

as metals, nutrients, or organic compounds. However, if sediments are (re)suspended (e.g., due to 

dredging, a storm event, or in conjunction with seasonal mixing and circulation patterns), the 

resuspension can lead to a temporary redox flux, including a localized and temporal release of any 

formerly sorbed metals or nutrients (Caetano et al., 2003; Fanning et al., 1982).

Offshore waters, especially deeper waters, are more directly affected by natural seeps (refer 

to Chapter 3.3.2.9.2). Hydrocarbons enter the Gulf of Mexico through natural seeps at a rate of 

approximately 980,392 bbl per year (a range of approximately 560,224-1,400,560 bbl per year) 

(NRC, 2003). Pelagic tar is a common form of hydrocarbon contamination present in the offshore 

environment of the GOM (USDHS, CG, 2015). Higher tar concentrations were closely correlated 
4-58 Gulf of Mexico Multisale EIS

with proximity to the Loop Current. Van Vleet et al. (1983) estimated that approximately 7,000 tons 

(7,112,323 kg, or about 60,000 bbl) of pelagic tar are discharged annually from the GOM into the 

North Atlantic Ocean and that roughly half of the oil may be brought into the GOM from the 

Caribbean Sea via the Loop Current, while the remainder appears to originate in the GOM.

The USEPA’s National Coastal Condition Report IV categorizes coastal waters of the United 

States based on an evaluation of five indices including water and sediment quality. The water 

quality index for the GOM’s coastal waters was rated fair, and the sediment quality index was rated 

poor (USEPA, 2012b). Sediment quality poses an impact risk to coastal water quality as 

contaminants in sediments may be resuspended into the water by anthropogenic activities, storms, 

or other natural events. Sediments in the GOM coastal region have been found to contain 

pesticides, metals, polychlorinated biphenyls (PCBs), and occasionally polycyclic aromatic 

hydrocarbons (PAHs) (USEPA, 2012b).

4.2.2 Environmental Consequences

4.2.2.1 Routine Activities

Impact-producing factors from routine activities that could affect water quality are identified in 

Chapter 3.1 and include

• geological sampling and bottom area disturbance including pipeline installation;

• operational discharges and wastes; and

• decommissioning and removal operations.

Geological Sampling and Bottom Area Disturbance Including Pipeline Installation

Geological sampling is performed for geological and geotechnical evaluation, using grab 

samples, box cores, and gravity, rotary, and piston core methods. Each of these sample techniques 

disturbs a small area of the seafloor (typically less than 1 ac [0.4 ha]), creating turbidity. Because 

these areas of disturbance are localized and short term, impacts from turbidity due to bottomdisturbing activities are considered negligible. 

Bottom area disturbances create turbidity and occur during geological sampling, 

emplacement and removal of jack-up drill rigs, anchored semisubmersible drill rigs and drillships, 

platforms, pipelines, and subsea production systems. The emplacement or removal of these 

structures disturbs areas of the seafloor beneath or adjacent to the structure. Anchored catenary 

systems may disturb an area of seafloor up to about 5-7 ac (2-3 ha). Trenching for emplacement of 

pipelines disturbs an area of seafloor up to 2.5 ac (1.0 ha) per kilometer of pipeline (Cranswick, 

2001). These bottom-disturbing activities impact water quality when sediments are resuspended, 

creating turbidity and resulting in a temporary redox flux, including a localized and temporal release 

of components such as metals or nutrients that were associated with the sediment, as described in 
Description of the Affected Environment and Impact Analysis 4-59

Chapter 4.2.1. Because these areas of disturbance are localized and short term, impacts from 

turbidity due to bottom-disturbing activities, including pipeline installation, are considered negligible. 

Operational Discharges and Wastes

Operational wastes and discharges are discussed in detail in Chapter 3.1.5.1. These 

wastes include drilling fluids (also known as muds) and cuttings, which are discussed in detail in 

Chapter 3.1.5.1.1. Water-based muds and cuttings are discharged at the seafloor during drilling of 

the shallow portion of the well, prior to installation of a surface riser. The resulting splay (pattern of 

mud distribution) on the seafloor may be up to 2,000 ft (610 m) in radius (British Petroleum, 2015), 

indicating that turbidity resulting from riserless drilling settles out relatively quickly. After the riser is 

installed, drilling muds and cuttings are generally discharged from the drilling unit at or near the 

water surface. The heavier mud and cuttings fall close to the drilling unit; however, the resulting 

turbidity plume may extend more than a mile from the drilling unit, depending on currents. Similar to 

bottom-disturbing activities, turbidity generated from drilling muds and cuttings is temporary and 

would settle out quickly. Unlike bottom-disturbing activities, turbidity from drilling muds and cuttings 

is less likely to result in a redox flux.

The USEPA (Regions 4 and 6) regulates the discharge of routine operational waste streams 

generated from offshore oil- and gas-related activities. Section 403 of the Clean Water Act requires 

that NPDES permits be issued for discharges to State territorial waters, the contiguous zone, and 

the ocean in compliance with USEPA’s regulations for preventing unreasonable degradation of the 

receiving waters. The authority for the NPDES program is Section 402 of the Clean Water Act, as 

codified in 40 CFR parts 121-125. The purpose of the NPDES program is to prevent the 

unreasonable degradation of the marine environment as described in 40 CFR § 125.122. In 

accordance with definitions stated at 40 CFR § 125.121, “unreasonable degradation of the marine 

environment” means (1) significant adverse changes in ecosystem diversity, productivity, and 

stability of the biological community within the area of discharge and surrounding biological 

communities; (2) threat to human health through direct exposure to pollutants or through 

consumption of exposed aquatic organisms; or (3) loss of aesthetic, recreational, scientific, or 

economic values, which is unreasonable in relation to the benefit derived from the discharge. 

Regulated wastes include drilling fluids, drill cuttings, deck drainage, produced water, produced 

sand, well treatment fluids, well completion fluids, well workover fluids, sanitary wastes, domestic 

wastes, and miscellaneous wastes. The bulk of waste materials produced by offshore oil- and gasrelated activities are produced water (formation water) and drilling muds and cuttings (USEPA, 

2009b). There are two general NPDES permits that cover the Gulf of Mexico. Permit GMG290000, 

issued by USEPA Region 6, covers the WPA and CPA; and Permit GEG460000, issued by USEPA 

Region 4, covers the EPA and a small part of the CPA. Updates to this permit are discussed in 

Chapter 3.1.5.1. The USEPA Regions’ jurisdictional areas are shown in Figure 3-10 (USEPA, 

2009b).

To meet the goal of preventing unreasonable degradation of the marine environment, 

Section B of the NPDES permits specifies effluent limitations and monitoring requirements for 
4-60 Gulf of Mexico Multisale EIS

offshore oil and gas facilities. Discharged regulated wastes may not contain free oil or cause an oil 

sheen on the water surface, and the oil/grease concentration may not exceed 42 milligrams per liter 

(mg/L) daily maximum or 29 mg/L monthly average. The discharge of drilling fluids containing oil 

additive or formation oil is prohibited, except that which adheres to cuttings and certain small volume 

discharges. Barite, used in drilling fluids, may not contain mercury or cadmium at levels exceeding 

certain concentrations (1.0 mg/kg mercury and 3.0 mg/kg cadmium). Wastes produced must also be 

characterized using a whole effluent toxicity test, where a population of mysid shrimp or inland 

silverside minnows are exposed to the waste stream, and mortality of the population must not 

exceed 50 percent. The NPDES permits allow a mixing zone as defined at 40 CFR § 125.121 to 

meet compliance using an approved plume model. The NPDES permits require no discharge within 

1,000 m (3,281 ft) of an area of biological concern. Region 4 also requires no discharge within 

1,000 m (3,281 ft) of any federally designated dredged material ocean disposal site.

The background (baseline) water quality conditions upstream (upcurrent) from discharging 

facilities under a proposed action are assumed to be free of “unreasonable degradation of the 

marine environment,” as defined at 40 CFR § 125.121 and summarized in Chapter 4.2 above. As 

discussed below, impacts on bottom sediments from the discharge of produced water have been 

observed at a distance of 1,000 m (3,281 ft).

Impacts on water quality from operational discharges related to a proposed lease sale are 

expected to be minimal because of the following: (1) USEPA regulations to prevent unreasonable 

degradation of the marine environment; (2) prohibitions on discharge of some waste types; 

(3) prohibitions on discharge near sensitive biological communities; (4) monitoring requirements and 

toxicity testing; (5) mixing zone and dilution factors; (6) operational discharges are temporary in 

nature; and (7) any effects from elevated turbidity would be short term, localized, and reversible. As 

such, assuming compliance with applicable regulations, the impacts from the discharge of regulated 

wastes from routine operations would require no additional mitigation. 

The potential toxic effects of water-based and synthetic-based fluid (SBF) drilling muds are 

discussed in Chapter 3.1.5.1.1. The SBF is nonpetroleum manufactured hydrocarbons incorporated 

into the barite mud matrix. The SBF is well-characterized, has low toxicity and bioaccumulation 

potentials, and is biodegradable. Also, SBF is not soluble in water and is therefore not expected to 

adversely affect water quality. A previous study of an SBF spill (USDOI, MMS, 2004a) concluded 

that the released SBF dispersed into the water, settled to the seafloor, and biodegraded. The SBF 

would cause a temporary decrease in dissolved oxygen at the sediment/water interface. The 

discharge of SBF-wetted cuttings is allowed under the USEPA Region 4 and Region 6 NPDES 

general permits. Discharge of muds containing SBF is prohibited. However, SBF-wetted cuttings 

may be discharged after free SBF has been removed (up to 9.4% of SBM may be retained on 

cuttings for ocean discharge). Under the guidance of the NPDES permit, drilling muds can be 

discharged into the ocean (except in biologically sensitive areas) only if they meet USEPA 

requirements, which include testing for toxicity prior to discharge. If they fail the toxicity test, the 

materials cannot be discharged into the ocean. The discharge of drilling muds that meet the 

required regulatory criteria but include very low quantities of SBFs appear to have minimal and brief 
Description of the Affected Environment and Impact Analysis 4-61

impacts to the ocean environment. As such, the impact from discharging drill cuttings is considered 

negligible. 

Produced water is discussed in Chapter 3.1.5.1.2. Produced water can degrade water 

and sediment quality in the immediate vicinity of the discharge as it can contain well treatment 

chemicals, dissolved solids from the geological formation, inorganic and organic chemicals, and 

radionuclides, some of which are toxic and persist in the marine environment.

The discharge of produced water is allowed under the USEPA Region 4 and Region 6 

NPDES general permits. The USEPA requires testing of produced water under the NPDES 

program. Analyses currently required by the NPDES permit include oil and grease (once per month, 

by gravimetric Method 10056) and chronic Whole Effluent Toxicity (once per 6 months after 

3 consecutive bimonthly tests for USEPA Region 4; once annually after 4 consecutive calendar 

quarters [if less than 4,599 bbl/day] for USEPA Region 6).

Both Regions 4 and 6 require that well treatment fluids, completion fluids, and workover 

(WTCW) fluids must not contain priority pollutants, except in trace amounts. This requirement does 

not currently apply to produced water. Fluids injected into boreholes during hydraulic fracturing are 

considered well treatment (acidizing) and workover (proppant injection) fluids, as discussed in 

Chapter 3.1.5.1.3. Flowback fluids from hydraulic fracturing are managed as WTCW fluids under 

the NPDES permit.

When WTCW fluids are intermingled with produced water, the discharges are considered 

produced water, and the operator may report “no discharge” of WTCW fluids for monitoring and 

reporting purposes (refer to USEPA Region 4 and Region 6 NPDES permits). The regulated 

industry self-reports the results of NPDES testing to USEPA for entry into the Integrated Compliance 

Information System (ICIS) database. 

Studies in coastal waters have shown contaminated sediments exist in areas up to 1,000 m 

(3,280 ft) from a produced-water discharge point, indicating that water quality in that zone has been 

affected by produced-water discharges (Rabalais et al., 1991). In shallow shelf waters, 

hydrocarbons from produced water have been shown to accumulate in bottom sediments up to 

300 m (984 ft) from an outfall (Rabalais et al., 1991). In offshore waters, contaminated sediments 

are localized around offshore platforms (NRC, 2003). Therefore, the potential impact from the 

discharge of produced water is considered negligible (beyond 1,000 m; 3,281 ft) to moderate

(within 1,000 m; 3,281 ft).

Furthermore, the loading of nitrogen and phosphorus in produced water discharged within 

the entire hypoxic zone are several orders of magnitude smaller than those entering the Gulf of 

Mexico from rivers. The total nitrogen loading from produced waters is about 0.16 percent and the 

total phosphorus loading is about 0.013 percent of the nutrient loading coming from the Mississippi 

and Atchafalaya Rivers (Argonne National Laboratory et al., 2005). As such, the incremental effect 

of produced water contributing to the effects of the hypoxic zone is considered negligible. 
4-62 Gulf of Mexico Multisale EIS

Other operational waste streams identified in Chapter 3.1.5 include bilge, ballast, and fire 

water; cooling water; deck drainage; and treated domestic and sanitary wastes. These waste 

streams are also discharged in accordance with the USEPA Region 4 and Region 6 NPDES general 

permits with requirements for the treatment method and prior analytical testing. Wastes that do not 

meet regulatory requirements for offshore discharge into the ocean must be properly disposed of or 

recycled onshore according to State and Federal regulations. Assuming compliance with these 

requirements under the general NPDES permit, the impact of the discharge on water quality is 

considered negligible. 

Discharges from supply/service vessels that support oil and gas operations are discussed in 

Chapter 3.1.5.2. These discharges typically include ballast water, trash and debris, and sanitary 

and domestic wastes. They are regulated under the NPDES Vessel General Permit (VGP), Small 

Vessel General Permit (sVGP), and the International Convention for the Prevention of Pollution from 

Ships, 1973 as modified by the Protocol of 1978 (MARPOL 73/78). All discharges of ballast water 

must comply with applicable U.S. Coast Guard regulations (33 CFR part 151). The NPDES permit 

defines mandatory ballast water practices required of all vessels. All discharges of oil, including oily 

mixtures, must not contain oil in quantities that may violate applicable water quality standards 

pursuant to 40 CFR part 110. Assuming compliance with these regulations, the impact of these 

discharges is considered negligible. 

Discharges related to the onshore disposal of OCS oil- and gas-related wastes (Chapter 

3.1.5.3) are limited to potential point-source runoff from the disposal facilities, which is regulated by 

the facility NPDES permit. Facility NPDES permits set discharge limits for each characterized waste 

stream to protect water quality standards of the receiving waters and require routine discharge 

monitoring to ensure compliance. As such, the impact of regulated point-source runoff on water 

quality is considered negligible. 

Decommissioning and Removal Operations

Potential impacts to water quality related to decommissioning and removal operations are 

discussed in Chapter 3.1.6. Requirements for decommissioning are stated at 30 CFR § 250.1703. 

These activities include permanently plugging all wells, removal of platforms and other facilities, 

decommissioning of pipelines, and clearing the seafloor of all obstructions. The regulation at 

30 CFR § 250.1750 allows pipelines (which may be interpreted to include umbilicals and jumpers 

that service a subsea completion) to be decommissioned in place if the pipeline does not constitute 

a hazard (obstruction) to navigation and commercial fishing operations, does not interfere with other 

OCS uses, and does not have adverse environmental effects. Pipelines decommissioned in place 

are required to be pigged, flushed, filled with seawater, and cut and plugged with the ends buried 

unless BSEE’s Regional Supervisor of Field Operations waives these requirements. In some cases, 

umbilicals containing fluids (methanol and hydraulic fluid) may be abandoned in place with BSEE’s 

Regional Supervisor of Field Operations’ approval if operational difficulties (such as clogged tubing 

or a lack of infrastructure) prevent flushing. Water quality impacts may occur from this practice; 

however, any future release from these umbilicals is expected to be slow and to disperse quickly. 
Description of the Affected Environment and Impact Analysis 4-63

Decommissioning activities may use both explosive and nonexplosive technologies to remove 

structures to a depth of at least 15 ft (5 m) below the mudline. Prior to decommissioning, all tanks 

formerly containing oil or hazardous materials are removed, such that the decommissioning may 

only result in turbidity from the associated bottom-disturbing activity and temporary redox flux that 

could cause a release of formerly-sorbed components. As stated in Chapter 3.1.6, it is anticipated 

that the majority of decommissioning activities would take place landward of the 800-m (2,625-ft) 

isobath, where naturally occurring turbidity and impacted sediments are more likely to exist. 

Because these areas of decommissioning are localized and short term, impacts from turbidity due to 

the associated bottom-disturbing activities are considered negligible. 

In summary, as OCS oil- and gas-related routine events are highly regulated, such that 

effects on water quality are short term, localized, and reversible, and therefore, they would be 

expected to have a negligible impact beyond 1,000 m (3,281 ft) from discharge outfalls.

4.2.2.2 Accidental Events

Impact-producing factors related to OCS oil- and gas-related accidental events are 

discussed in Chapter 3.2. These events primarily involve drilling fluid spills, chemical and waste 

spills, and oil spills. 

Drilling Fluid Spills

Water-based fluid (WBF) and SBF spills may result in elevated turbidity, which would be 

short term, localized, and reversible. The WBF is normally discharged to the seafloor during 

riserless drilling, which is allowable due to its low toxicity. For the same reasons, a spill of WBF 

would have negligible impacts. As discussed in Chapter 3.1.5.1.1, the SBF has low toxicity, and 

the discharge of SBF is allowed to the extent that it adheres onto drill cuttings. Both USEPA 

Regions 4 and 6 permit the discharge of cuttings wetted with SBF as long as the retained SBF 

amount is below a prescribed percent, meets biodegradation and toxicity requirements, and is not 

contaminated with the formation oil or PAH. A spill of SBF may cause a temporary increase in 

biological oxygen demand and locally result in lowered dissolved oxygen in the water column. Also, 

a spill of SBF may release an oil sheen if formation oil is present in the fluid. Therefore, impacts 

from a release of SBF are considered to be minor. Spills of SBF typically do not require mitigation

because SBF sinks in water and naturally biodegrades, seafloor cleanup is technically difficult, and 

SBF has low toxicity.

Chemical and Waste Spills

Accidental chemical spills could result in temporary localized impacts on water quality,, 

primarily due to changing pH. Chemicals spills are generally small volume compared with spills of 

oil and drilling fluids. As stated in Chapter 3.2.6, during the period of 2007 to 2014, small chemical 

spills occurred at an average annual volume of 28 bbl, while large chemical spills occurred at an 

average annual volume of 758 bbl. These chemical spills normally dissolve in water and dissipate 

quickly through dilution with no observable effects. Also, many of these chemicals are approved to 
4-64 Gulf of Mexico Multisale EIS

be commingled in produced water for discharge to the ocean, which is a permitted activity. 

Therefore, impacts from chemical spills are considered to be minor and do not typically require 

mitigation because of technical feasibility and low toxicity after dilution.

Oil Spills

Oil spills have the greatest potential of all OCS oil- and gas-related activities to affect water 

quality. Small spills (<1,000 bbl) are not expected to substantially impact water quality in coastal or 

offshore waters because the oil dissipates quickly through dispersion and weathering while still at 

sea. Reasonably foreseeable larger spills (≥1,000 bbl), however, could impact water quality in 

coastal and offshore waters. Scenarios and impacts from very large oil spills are discussed in the 

Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017). Oil spills, regardless of size, 

may allow hydrocarbons to partition into the water column in a dissolved, emulsion, and/or 

particulate phase. Therefore, impacts from reasonably foreseeable oil spills are considered 

moderate. Mitigation efforts for oil spills may include booming, burning, and the use of dispersants

(Chapter 3.2.8.2). These methods may cause short-term secondary impacts to water quality, such 

as the introduction of additional hydrocarbon into the dissolved phase through the use of dispersants 

and the sinking of hydrocarbon residuals from burning. Since burning and the use of dispersants put 

additional hydrocarbons into the dissolved phase, impacts to water quality after mitigation efforts are 

still considered to be moderate, because dissolved hydrocarbons extend down into the water 

column resulting in additional exposure pathways via ingestion and gill respiration, and may result in 

acute or chronic effects to marine life.

4.2.2.3 Cumulative Impacts

Since routine and operational discharges from OCS oil- and gas-related activities are 

considered to dilute rapidly in the marine environment, particularly in deep water, this impact 

analysis considers the potential effects within 1,000 m (3,281 ft) from each OCS oil- and gas-related 

waste discharge point, since this is the maximum distance of known produced water impacts. As 

such, impacts on water quality from other discharging facilities, whether pre-existing or as part of a 

proposed action, are not expected to be additive because the areas of impact generally do not 

overlap (except where multiple outfalls may exist at a facility). For the same reason, impacts on 

water quality from discharging facilities are not expected to be additive with the other non-OCS 

impact-producing factors identified in Chapter 3.3.2.3. 

The background (baseline) water quality conditions upstream (upcurrent) from discharging 

facilities under a proposed action are assumed to be free of “unreasonable degradation of the 

marine environment,” as defined at 40 CFR § 125.121 and summarized in Chapter 4.2 above.

OCS Oil- and Gas-Related Impacts

As noted in Chapter 4.2.2.1, routine OCS oil- and gas-related impacts are considered to be 

a small contribution to cumulative impacts because they are considered to be negligible to 

moderate (refer to Chapter 3.3.1). Accidental OCS Program spills of drilling fluids, chemicals, and 
Description of the Affected Environment and Impact Analysis 4-65

oil are considered to have moderate impacts. However, other contaminant sources unrelated to the 

OCS Oil and Gas Program contribute significant impacts to water quality in the GOM, as discussed 

below.

Non-OCS Oil- and Gas-Related Impacts

Impact-producing factors related to non-OCS oil- and gas-related anthropogenic events and 

natural processes discussed below are described in Chapter 3.3.2. These cumulative effects are 

important for comparison with OCS oil- and gas-related effects relative to their potential impacts on 

water quality. 

Non-OCS oil-and gas-related anthropogenic impacts that are regulated include non-OCS 

oil-and gas-related activities in State waters, marine vessel activity, LNG ports and terminals, 

land-based point-source discharges, aquaculture, OCS sand borrowing, maintenance dredging, and 

dredged material disposal. Discharges as a result of these activities require NDPES permits. 

Discharges in compliance with regulations, including the NPDES permit and other provisions of the 

Clean Water Act, are considered negligible because the regulations are risk-based to assure little to 

no effect on marine life, and monitoring is required to demonstrate compliance. Therefore, the 

impacts on water quality from these activities are considered negligible. 

Unregulated anthropogenic activities often have associated impacts on water quality of 

greater magnitude than regulated activities. Non-OCS oil- and gas-related oil spills present the 

same impacts as described above for OCS oil- and gas-related spills. Land-based nonpoint-source 

discharges from uncontained runoff and groundwater discharge are a source of suspended solids, 

organic matter, nutrients, and other pollutants in river outflow. Nutrients in river outflow cause 

eutrophication and hypoxia, which can cause unreasonable degradation of the marine environment. 

Therefore, impacts to water quality from hypoxia are considered major. The trend in the hypoxic 

zone area shows a relatively constant long-term average value of 14,000 km2 (8,700 mi2

). Pollutants 

in nonpoint-source discharges are incorporated into bottom sediments within the coastal zone and 

have the potential to cause impacts to water quality. Therefore, impacts to sediments from nonpointsource discharges are considered moderate. 

Discharges associated with military activities (Chapter 3.3.2.3.2) were evaluated for their 

potential impacts to water quality. Debris released to into the GOM as a result of military activities 

may contain jettisoned fuel, propellants, aluminum, copper, lead, flares, smokes, and obscurants, 

which can impact water quality. These impacts are short term; therefore, the associated impacts to 

water quality are considered minor. 

Potentially polluting shipwrecks (e.g., bulk cargo and fuel leakage from the wreck) and 

chemical weapon disposal areas, which may cause potential impacts to water quality, are discussed 

in Chapters 3.3.2.3.1 and 3.3.2.3.3. The potential impacts to water quality from shipwrecks are 

dependent on the type of fuel and cargo present on the wreck and the flow rate of contaminants into 

the water column. Light oils released from wrecks are localized and generally degrade in the short 
4-66 Gulf of Mexico Multisale EIS

term, and may present only minor impacts to water quality. Chemical weapons were known to 

contain extremely toxic substances that, if leaked into the water column, could impact water quality 

over the long term. Some of the known disposal areas are in shallow waters, and there have been 

occurrences where trawlers have inadvertently raised 55-gallon drums suspected of containing 

chemical weapons. Since potential exposures to marine organisms and potentially the food chain 

from these substances may occur via the water column, the impacts to water quality are considered 

moderate. 

Natural events also contribute to cumulative impacts on water quality resulting from oil seeps 

and turbidity caused by suspended sediment load from rivers and erosion from currents, storms, and 

downslope sediment transport. Hurricanes, human error, and acts of terrorism may increase the 

potential for spills. Chapter 3.4 of the Five-Year Program EIS discusses the risk of these 

low-probability catastrophic discharge events. Oil seeps (Chapter 3.3.2.9.2) present the same 

potential impacts as a small-scale accidental oil spill, except that the seeps may persist over the long 

term and are not subject to mitigation. Much of the oil from seeps may biodegrade before it reaches 

the surface. As such, the impacts to water quality are considered minor. Natural turbidity persists in 

coastal waters due to river outflow and may be intermittent in response to currents, storms, and 

downslope sediment transport. The effects from the elevated turbidity on water quality would be 

short term, localized, and reversible, and are considered minor. 

Impacts from climate change are also considered potential cumulative impacts to water 

quality. These impacts include decreased oxygen (Long et al., 2016), changing nutrient loads, and 

altered ocean circulation (Brierley and Kingsford, 2009). Ocean acidification results from the 

increased concentration of carbon dioxide in the atmosphere (Feely et al., 2009; Doney et al., 2009). 

Excess atmospheric carbon dioxide partitions into the water column, forming carbonic acid and 

lowering the seawater pH. This chemical alteration leads to a decrease in carbonate ions, which are 

used in the formation of calcium carbonate. The natural ocean system buffers the lowered pH by 

liberating more calcium carbonate ions from seafloor sediments, which raises seawater pH to 

achieve equilibrium (Broeker and Takahashi, 1977). These ionic concentrations are critical to 

marine organisms that utilize calcium carbonate in their skeleton and shell formation. This complex 

process occurs on a global scale, resulting from a multitude of past and present atmospheric carbon 

dioxide sources, both naturally occurring and of anthropogenic origin, and affecting calcium 

carbonate deposits in shallow and deep water. Due to the complexity of the ocean acidification 

process, estimation of the incremental change in seawater pH as a result of a proposed action is 

beyond the scope of this Multisale EIS.

Incremental Cumulative Impacts

The impacts of routine operational discharges from the OCS oil and gas program on water 

quality are short term and localized, and are considered negligible to moderate. The potential 

impacts from reasonably foreseeable oil spills as a result of the proposed action on water quality 

after mitigation are also short term and are considered minor. The impacts from a proposed lease 

are a small addition to the cumulative impacts on water quality when compared with inputs from 
Description of the Affected Environment and Impact Analysis 4-67

hypoxia, potentially leaking shipwrecks, chemical weapon dumpsites, natural oil seeps, and natural 

turbidity. The incremental contribution of the routine activities and accidental discharges associated 

with a proposed lease sale to the cumulative impacts on water quality would be negligible. 

4.2.2.4 Incomplete or Unavailable Information

In preparation for this Multisale EIS, BOEM has reviewed the latest information available 

relative to the potential impact-producing factors on water quality, which is presented in Chapter 3.1. 

Much of the information pertaining to water quality impacts from the Deepwater Horizon oil spill and 

response has been discussed in previous NEPA documents, and water quality has recovered from 

this oil spill and response. BOEM has identified incomplete or unavailable information that may be 

relevant to reasonably foreseeable impacts on water quality. Much of this information relates to nonOCS oil- and gas- related impacts. Specifically, potentially polluting shipwrecks and chemical 

weapon disposal areas may cause potential impacts to water quality and the marine environment. 

There are no publicly available data regarding these potential impacts because no agency has been 

tasked with this responsibility. It is not foreseen that this information would be publicly available to 

include in this NEPA analysis regardless of the costs or resources needed. BOEM has used the 

best available scientific information to date and believes that any additional information would not 

likely change the ranking of impacts and is not essential to a reasoned choice among alternatives.

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

This chapter summarizes the potential impacts of routine activities, accidental events, and 

cumulative impacts associated with Alternative A on water quality. Under Alternative A, BOEM 

would hold a regionwide lease sale comprised of the WPA, CPA, and a portion of the EPA. BOEM 

estimates that a total of 53-984 exploration and delineation wells and 61-767 development and 

production wells would be drilled and that 221-1,332 mi (355-2,144 km) of pipeline would be installed 

over a 50-year period. The projected number of drilled wells and miles of pipeline are used as an 

indicator of total activity, which correlates to the volume of routine operational waste discharged. 

Figures 3-5 and 3-6 show the expected duration of exploration/delineation and production well 

drilling over the 50-year period. As stated in Chapter 3.1.2, exploratory drilling activity would likely 

occur over the course of each lease, but it could begin within 1 year. As discussed in Chapter 3.1.3, 

the majority of development well drilling would likely occur in the first 25 years of each lease, and 

production of oil and gas could begin by the 3rd year after the lease sale and would generally 

conclude by the 50th year. Therefore, the discharge of drilling-related operational wastes (drill 

cuttings and mud, turbidity) and the potential for accidental drilling fluid and chemical/oil spills could 

be expected to occur from 1 to 25 years after a lease sale. The discharge of produced water, which 

primarily occurs in shallow water, could be expected from 3 to 50 years after a lease sale.

Routine operational discharges may result in localized negligible impacts from the discharge 

of SBF-wetted drill cuttings and long-term moderate impacts from the discharge of produced water 

and WTCW fluids within 1,000 m (3,281 ft) from outfalls. These impacts are unavoidable, and no 

mitigation exists for these discharges. Based on the previously discussed impact-producing factors 

for routine activites and accidental events and their estimated level of activity and occurrence across 
4-68 Gulf of Mexico Multisale EIS

the entire proposed lease sale area, cumulative impacts to water quality under Alternative A is 

expected to be minor to moderate. The incremental contribution of the routine activities and 

accidental events associated with a single proposed lease sale to the overall cumulative impacts to 

water quality under Alternative A would be negligible. 

4.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM estimates that a total of 33-893 exploration and delineation wells 

and 46-671 development and production wells would be drilled and that 158-1,020 mi 

(254-1,641 km) of pipeline would be installed over a 50-year period. The projected number of wells 

and miles of pipeline are used as an indicator of total activity, which correlates to the volume of 

routine operational waste discharged, amount of bottom disturbance and drill cuttings causing 

turbidity, and the potential for drilling fluid and chemical and oil spills. Based on the previously 

discussed impact-producing factors for routine activities and accidental events, their estimated level 

of activity, commonly applied mitigating measures,and occurring mostly in the CPA/ and EPA portion 

of the proposed lease sale area, Alternative B is expected to result in minor to moderate impacts to 

water quality. The incremental contribution of the routine activities and accidental events associated 

with a single proposed lease sale to the overall cumulative impacts to water quality under 

Alternative B would be negligible. As under Alternative A, some localized and short-term negligible 

impacts as a result of drilling and long-term moderate impacts could occur; moderate impacts may 

occur from the discharge of produced water within 1,000 m (3,281 ft) of an outfall for site-specific 

actions. The environmental consequences of a proposed lease sale under Alternative B and the 

inherent resulting activities to water quality would be slightly smaller than proposed in Alternative A 

and would be more restricted to the CPA/EPA portion of the proposed lease sale area.

4.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Under Alternative C, BOEM estimates that a total of 17-91 exploration and delineation wells 

and 22-96 development and production wells would be drilled and that 65-314 mi (105-505 km) of 

pipeline would be installed over a 50-year period. While all of the leases issued under this 

alternative would occur in the WPA portion of the proposed lease sale area, activities such as vessel 

support and pipeline or coastal infrastructure construction could occur in the CPA portion of the 

proposed lease sale area. Based on the estimated level of activity and much smaller geographic 

area, Alternative C is expected to result in minor to moderate impacts, though fewer impacts than 

Alternative A or B. The incremental contribution of the routine activities and accidental events 

associated with a single proposed lease sale to the overall cumulative impacts to water quality under 

Alternative C would be negligible. 
Description of the Affected Environment and Impact Analysis 4-69

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

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

Blocks South of Baldwin County, Alabama, Stipulations

The number of available unleased blocks subject to the Topographic Features, Live Bottom

(Pinnacle Trend), and Blocks South of Baldwin County, Alabama, Stipulations is small compared 

with the number of unleased blocks being offered under Alternatives A, B, or C. Therefore, the 

activity level (and water quality impacts) that can be expected for Alternative D is similar to 

Alternative A, B, or C, as applicable, which would be minor to moderate under all action 

alternatives. The incremental contribution of the routine activities and accidental events associated 

with a single proposed lease sale to the overall cumulative impacts to water quality under 

Alternative D would be negligible. 

4.2.2.9 Alternative E—No Action

Under Alternative E, there would be no new activities related to the proposed action (no wells 

drilled and no pipelines installed). The resulting development of oil and gas would most likely be 

postponed to a future lease sale; therefore, the overall level of OCS oil- and gas-related activity 

would only be reduced by a small percentage, if any. The environmental impacts expected to result 

from a proposed action, which is described above, would not occur in the short term, but they would 

likely be postponed to any future lease sale and likely would not require oil and gas substites from 

other sources. The cancellation of a proposed lease sale would not significantly change the 

environmental impacts of overall OCS oil- and gas-related activity in the long term. Therefore, there 

would be no associated impacts to water quality resulting from a proposed lease sale, and additional 

impacts would be none.

4.3 COASTAL HABITATS

4.3.1 Estuarine Systems (Wetlands and Seagrass/Submerged Vegetation) 

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

can consist of many habitats, including wetlands and submerged vegetation. While some seagrass

species can be found farther offshore, the majority is within the coastal area of the GOM and will be 

covered in this chapter. The approach of the analysis is to focus on the potential impact-producing 

factors from routine OCS oil- and gas-related activities (i.e., exploration, development, and 

production), as well as accidental events and cumulative impacts. The potential magnitude for each 

of these impact-produring factors is provided in Table 4-9 to help the reader quickly identify the level 

of potential impacts for each impact-producing factor. The impact-level definitions and the analyses 

supporting these conclusions are then discussed in detail in this chapter.
4-70 Gulf of Mexico Multisale EIS

Table 4-9. Estuarine Systems Impact-Producing Factors That Are Reasonably Foreseeable.

Estuarine Systems Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Pipeline Construction 

and Maintenance Negligible Negligible Negligible Negligible None

Navigation Channel 

Maintenance 

Dredging

Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Vessel Operation 

(support use of 

navigation channels)

Moderate Moderate Minor Moderate None

Disposal of OCS Oiland Gas-Related 

Wastes

Negligible Negligible Negligible Negligible None

Construction and Use 

of Coastal Support 

Infrastructure

Negligible Negligible Negligible Negligible None

Accidental Impacts

Oil Spills Minor Minor Minor Minor None

Cumulative Impacts

Incremental 

Contribution2 Moderate Moderate Minor Moderate None

OCS Oil and Gas3 Major

Non-OCS Oil and 

Gas4 Major

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

In this chapter, BOEM reviewed and analyzed routine OCS oil- and gas-related activities and 

reasonably foreseeable accidental events. Routine activities associated with a proposed lease sale 

that take place on the OCS, where wells are drilled and platforms and pipelines are installed, would 

not impact the wetlands or submerged vegetation that is located miles away. Other routine activities 

that support offshore oil and gas exploration, such as increased vessel traffic (Chapter 3.1.4.3), 

maintenance dredging of navigation canals (Chapter 3.1.3.3.4), pipeline installation (Chapter 

3.1.3.3.1), disposal of OCS oil- and gas-related wastes (Chapter 3.1.5), and construction and 

maintenance of support infrastructure in the coastal areas (Chapter 3.1.7), could potentially impact 

wetlands. Of these impact-producing factors, vessel traffic was not analyzed with respect to 

seagrass and submerged vegetation because OCS vessels (due to their size and use of commercial 
Description of the Affected Environment and Impact Analysis 4-71

ports) are generally not in areas shallow enough to have large submerged vegetation beds. An 

analysis of the potential impacts from accidental events, primarily oil spills, associated with a 

proposed lease sale is presented in this chapter, as is the incremental contribution of a proposed 

action to the cumulative impacts to wetlands and submerged vegetation. Cumulative impacts were 

analyzed for OCS oil- and gas-related activities and for other sources that could affect wetlands and 

submerged vegetation communities (i.e., human impacts, storms, and vessel traffic). Additional 

factors that could affect estuarine systems include subsidence and sea-level rise.

Impact-Level Definitions

For this analysis, the following definitions were used to categorize impacts to wetlands and 

submerged vegetation: 

• Negligible – Little to no measurable impacts in the surrounding habitat (i.e., 

wetland segment and seagrass bed).

• Minor – Noticeable but short-term and localized impacts.

• Moderate – Damage to coastal habitats that is noticeable, spatially extensive, 

and long term or permanent.

• Major – Widespread, permanent loss of habitat; changes in species composition 

and abundance and/or altered ecological function well beyond that of normal 

variability. Changes would likely be both long lasting and spatially extensive for 

such an effect.

4.3.1.1 Description of the Affected Environment

The Mississippi Delta sits atop a pile of Mesozoic and Tertiary-aged sediments up to 7.5 mi 

(12.2 km) thick at the coast and it may be as much as 60,000 ft (18,288 m) or 11.4 mi (18.3 km) thick 

offshore (Gagliano, 1999). Five major lobes are generally recognized within about the uppermost 

50 m (164 ft) of sediments (Britsch and Dunbar, 1993; Frazier, 1967, Figure 1). The oldest lobe 

contains peat deposits dated as 7,240 years old (Frazier, 1967). The youngest delta lobe of the 

Mississippi Delta is the Plaquemines-Balize lobe that has been active since the St. Bernard lobe was 

abandoned about 1,000 years ago. The lower Mississippi River has shifted its course to the Gulf of 

Mexico every thousand years or so, seeking the most direct path to the sea while building a new 

deltaic lobe. Older lobes were abandoned to erosion and subsidence as the sediment supply was 

shut off. Because of the dynamics of delta building and abandonment, the Louisiana coastal area 

(U.S. Dept. of the Army, COE, 2004) experiences relatively high rates of subsidence relative to more 

stable coastal areas eastward and westward.

4.3.1.1.1 Wetlands

A recent evaluation of wetland trends in the U.S. covering the period from 2004 to 2009 

indicated that in 2009 there were 15.4 million ac (6.2 million ha) of coastal wetlands (including 

saltwater and freshwater wetlands) in the GOM region, a downward trend of 257,150 ac 
4-72 Gulf of Mexico Multisale EIS

(104,065 ha) (Dahl and Stedman, 2013) (Figure 4-8). In 2009, there were approximately 

3.35 million ac (1.35 million ha) of intertidal wetlands in the GOM coastal region, which was a decline 

of approximately 2.8 percent since 2004 and represents 99 percent of all intertidal wetland losses 

across the three coastal regions of the conterminous U.S. These losses have been attributed to the 

effects of severe coastal storms, land subsidence, sea-level rise, and the construction of levees 

along the Mississippi River. In coastal Louisiana and Texas, oil, gas, and groundwater extractions 

have contributed to subsidence and relative sea-level rise (Dahl, 2011). A small percentage is 

attributed to discrete anthropogenic actions (Dahl and Stedman, 2013).

Figure 4-8. Coastal Watersheds of the Upper Gulf of Mexico Showing the Magnitude of Saltwater

(intertidal) Wetland Loss to Open Water, 2004 to 2009 (from Dahl and Stedman, 2013).

An estimated 3.9 million ac (1.6 ha) of wetlands existed on the Texas coast in 1992. 

Approximately 210,600 ac (85,227 ha) had been lost since 1955. Approximately 1.7 million ac 

(687,966 ha) or 52 percent of the freshwater wetlands were classified as farmed wetlands. The 

greatest losses were of freshwater emergent and forested wetlands (Moulton et al., 1997). The 

major cause was faulting and land subsidence due to the withdrawal of underground water and oil 

and gas (onshore), which has resulted in the submergence of marshes (Moulton et al., 1997).

Coastal Louisiana, which contains about 37 percent of the estuarine herbaceous marshes in 

the conterminous U.S. and which supports the largest commercial fishery in the lower 48 States 

(Chapter 4.10), currently accounts for about 90 percent of the total coastal wetland loss in the 

continental U.S. (Couvillion et al., 2011). Coastal Louisiana has undergone a net change in land 

area of about -1,883 mi2

 (-4,877 km2) from 1932 to 2010. Ninety-five percent of this loss is due to 

continual loss of land through subsidence, saltwater intrusion, and other factors. The wetland loss 

rate for Louisiana has slowed from 42 mi2

/yr (27,000 ac/yr) during the late 1960’s to a rate of 

16.57 mi2 (43 km2

) per year from 1985 to 2010 (Couvillion et al., 2011). Separating the causes of 

such land loss is difficult, but one study estimated that the total of direct and indirect impacts from 
Description of the Affected Environment and Impact Analysis 4-73

OCS oil- and gas-related activities from 1955 to 1978 accounted for 21,863-49,884 ha 

(54,024-123,266 ac) or 8-17 percent of Louisiana’s total wetland loss (Turner and Cahoon, 1987).

In 1999, Mississippi had approximately 64,000 ac (25,900 ha) of vegetated coastal wetlands

(State of Mississippi, Department of Marine Resources, 1999). Estuarine wetlands are common in 

Mississippi and include marshes, mud flats, and forested wetlands. The estuarine marshes around 

Mississippi Sound and associated bays occur in discontinuous bands. The most extensive coastal 

wetland areas in Mississippi occur in the eastern Pearl River delta near the Louisiana/Mississippi 

border and in the Pascagoula River delta area near the Mississippi/Alabama border. Mississippi’s 

wetlands seem to be more stable than those in Louisiana and Alabama (State of Mississippi, 

Department of Marine Resources, 1999; Wallace, 1996; Couvillion et al., 2011). Urban and 

suburban growth are suggested as the greatest contributors to direct coastal wetland loss in 

Mississippi and Alabama.

Alabama has approximately 118,000 ac (47,753 ha) of coastal wetlands. Between 1955 and 

1979, 69 percent of the freshwater marsh and 29 percent of the estuarine marsh were lost (Wallace, 

1996). Most coastal wetlands in Alabama occur on the Mobile River Delta or along the northern 

Mississippi Sound. Both Mississippi and Alabama have estuarine intertidal emergent habitats that 

include salt marsh, as well as intertidal forested/shrub that can include mangroves and other salttolerant shrubs. Urban and suburban growths are suggested as the greatest contributors to direct 

coastal wetland loss in Mississippi and Alabama.

Florida wetlands, at one time estimated to encompass over 20 million ac (8.1 million ha), 

have been converted through draining, dredging, filling, and flooding, until by 1996, approximately 

11.4 million ac (4.6 million ha) remained (Dahl, 2005). Wetland loss rates in Florida, as high as 

72,000 ac (29,137 ha) per year from the mid-1950’s to the mid-1970’s, declined by nearly 80 percent 

to 5,000 ac (2,023 ha) per year between 1985 and 1996. This decline was due largely to increased 

regulation and elimination of incentives for wetland drainage. Public education, protection programs, 

and policies that promoted wetland restoration and creation also contributed (Dahl, 2005).

Florida’s salt marshes are most abundant on its central and northern coastlines (Mitsch and 

Gosselink, 2000). They are dominant along the Big Bend area of the Gulf Coast in low-energy 

shorelines, sands, lagoons, and bays. Florida’s coastal zone contained approximately 21 percent of 

the estuarine and marine wetlands of the conterminous U.S. and 92 percent of estuarine shrub 

wetlands in 1996.

Coastal wetlands and barrier islands are complex systems that provide many important 

functions. One of these functions is as a front line of defense against storm surge. High organic 

productivity and efficient nutrient recycling are characteristic of coastal wetlands. These wetland 

corridors provide habitat for a great number and wide diversity of resident plants, invertebrates, 

fishes, reptiles, birds, and mammals. Marsh environments are particularly important nursery 

grounds for many economically important fish and shellfish juveniles. The marsh edge, where 

marsh and open water come together, is particularly important for its higher productivity and greater 
4-74 Gulf of Mexico Multisale EIS

concentrations of organisms. Emergent plants produce the bulk of the energy that supports saltmarsh dependent animals.

The intensity and frequency of hurricanes in the GOM in recent years has greatly impacted 

the system of protective barrier islands, beaches, and dunes and associated wetlands along the Gulf 

Coast. Gulf shorelines have lost existing beach dunes and have experienced a decrease in beach 

ridge elevations, and barrier islands and wetlands have lost acreage to wave erosion due to 

hurricanes. As a result of decreased dune and barrier island elevations, as well as associated 

marshes and backshore and foreshore wetlands, the inland coasts and wetlands are more 

vulnerable to future hurricanes and wind-driven tidal or storm events.

The Deepwater Horizon oil spill was the largest spill ever recorded in the GOM and resulted 

in the oiling of an extensive portion of the northern Gulf Coast shoreline from Texas to northwest 

Florida (Florida Panhandle) (OSAT-2, 2011). Oil from the Deepwater Horizon explosion and oil spill 

was documented to have stranded on approximately 687 mi (1,105 km) of marsh shoreline (Nixon 

et al., 2016). In most areas, the oil stranded along the marsh edge, usually spreading into the marsh 

no more than about 33-49 ft (10-15 m) perpendicular to the shoreline. In the areas of heaviest oiling, 

the width of the impacted area was 56.4 ft (17.1 m). Cleanup activities were conducted on 

8.9 percent of the affected marsh (Michel et al., 2013a; Deepwater Horizon Natural Resource 

Damage Assessment Trustees, 2016). Various cleanup techniques were employed, but as of 2012, 

recovery was not complete and negative effects were ongoing (Zengel et al., 2015).

4.3.1.1.2 Submerged Aquatic Vegetation

Submerged aquatic vegetation can be defined as the collection of benthic plants that settle 

and grow in the marine and estuarine waters but that do not emerge from it. Distribution and 

composition of the species present depend on an interrelationship among a number of 

environmental factors, including water temperature, depth, turbidity, salinity, turbulence, and 

substrate suitability (Kemp, 1989; Onuf, 1996; Short et al., 2001). In high salinity waters, submerged 

aquatic vegetation are marine seagrasses that generally occur in relatively shallow and clear 

protected waters with substrates firm enough to enable colonization (Short et al., 2001). For 

estuarine waters with low salinity, submerged aquatic vegetation may include several species of 

vegetation typically considered to be freshwater species but are tolerant of low levels of salinity 

(Castellanos and Rozas, 2001). In the higher salinity waters of the GOM, there are five true 

seagrass species and one similar species, although not technically a true seagrass (Zieman, 1982; 

Short et al., 2001; Berns, 2003; Handley et al., 2007; Cho and May, 2008). Where salinity is lower, 

there are four genera that routinely comprise the community (Castellanos and Rozas, 2001; Cho and 

May, 2008). Submerged vegetative habitats are important in carbon sequestration, nutrient cycling, 

and sediment stabilization (Heck et al., 2003; Duarte et al., 2005; Orth et al., 2006; Frankovich et al., 

2011). Submerged vegetation functions as an important habitat for many species by providing 

protection from predation. It also provides food resources for associated infaunal species, nekton, 

and other megaherbivores and over wintering waterfowl (Rozas and Odum, 1988; Rooker et al., 

1998; Castellanos and Rozas, 2001; Heck et al., 2003; Orth et al., 2006; Maiaro, 2007). One of the 
Description of the Affected Environment and Impact Analysis 4-75

more important functions of submerged aquatic vegetation systems is the transfer of primary 

production from epiphytic algae into the ecosystem via grazing of those epiphytes by secondary 

consumers; however, without grazers, excessive epiphyte growth can become a hindrance to growth 

(Howard and Short, 1986; Bologna and Heck, 1999; Heck et al., 2006).

According to the most recent and comprehensive data available, approximately 

1.25 million ac (500,000 ha) of seagrass beds are estimated to exist in exposed, shallow 

coastal/nearshore waters and embayments of the GOM; over 80 percent of these beds are in Florida 

Bay and Florida coastal waters (calculated from Handley et al., 2007). In the northern GOM from 

south Texas to Mobile Bay, seagrasses occur in relatively small beds behind barrier islands in bays, 

lagoons, and coastal waters (Figure 4-9), while freshwater submerged aquatic vegetation occurs in 

the upper regions of estuaries and rivers (Onuf, 1996; Castellanos and Rozas, 2001; Handley et al., 

2007). Increased nutrients and sediments from natural (e.g., tropical cyclones) or anthropogenic 

events (e.g., nutrient loading, sedimentation, and declining water quality) are common and are a 

significant cause of seagrass declines worldwide (Orth et al., 2006; Carlson and Madley, 2007; 

Waycott et al., 2009). The USGS’s Seagrass Status and Trends in the Northern Gulf of Mexico: 

1940-2002 demonstrated a decrease of seagrass coverage across the northern Gulf of Mexico from 

the bays of Texas to the Gulf shores of Florida; this loss was from approximately 1.02 million ha 

(2.52 million ac) estimated in 1992 to approximately 500,000 ha (1.25 million ac) calculated in the 

2002 report (Handley et al., 2007). While declines have been documented for different species in 

different areas, it is difficult to estimate rates of decrease because of the fluctuation of biomass 

among the different species seasonally and yearly.

Figure 4-9. Seagrass Locations of the Northern Gulf of Mexico.

These coastal habitats also play an important role to ESA-listed species; BOEM consults on 

these species with FWS and NMFS. These species include nearshore fishes, sea turtles, beach 

mice, and birds; to read about the protected species that use these habitats, refer to Chapters 4.7
4-76 Gulf of Mexico Multisale EIS

(Fish and Invertebrate Resources), 4.9.2 (Sea Turtles), 4.9.3 (Beach Mice), and 4.9.4 (Protected 

Birds).

4.3.1.2 Environmental Consequences

4.3.1.2.1 Routine Activities

Impact-producing factors and scenarios for routine operations can be found in Chapter 3.1. 

In this chapter, consideration is given to impacts to coastal wetlands, marshes, and submerged 

aquatic vegetation from routine activities associated with a proposed lease sale. The primary 

impact-producing factors associated with a proposed lease sale that could affect wetlands and 

marshes include pipeline emplacement, construction, and maintenance; navigation channel use 

(vessel traffic) and maintenance dredging; disposal of OCS oil- and gas-related wastes; and use and 

construction of support infrastructure in these coastal areas.

Pipeline Emplacement

Many existing OCS pipelines make landfall on barrier island and wetland shorelines 

(Chapter 3.1.3.3.1). Approximately 4,971 mi (8,000 km) of OCS oil- and gas-related pipelines cross 

marsh and upland habitat in Louisiana (USDOI, MMS, 2007c). Wetlands protect pipelines from 

waves and help to keep the lines buried and in place. At least two studies have shown a connection 

between land loss and existing pipelines. One study indicated that existing pipelines have caused 

direct land loss averaging 6 ac (2.43 ha) per linear km of pipeline for the 1955-1978 time period 

(Bauman and Turner, 1990). Bauman and Turner (1990) also indicated that the widening of OCS 

pipeline canals does not appear to be an important factor for total net wetland loss in the coastal 

zone because few pipeline canals are open to navigation. In contrast, Johnston et al. (2009) found 

that land loss was consistently higher in the vicinity of pipelines compared with more general, 

regional trends of land loss, suggesting that they contributed to the loss.

Modern pipeline construction typically employs horizontal, directional (trenchless) drilling 

techniques and open-water routes to the extent possible to avoid damages to estuarine systems 

(i.e., emergent wetlands and submerged vegetation beds) and beaches. Similar features are now 

commonly required to minimize any impacts from pipeline landfalls. Currently, no new construction 

of flotation canals (the most harmful construction technique) is being allowed in vegetated areas 

(Johnston et al., 2009). There is only 0-1 pipeline landfalls projected to result from a proposed 

action. About 12-20 ac (5-8 ha) of land loss for the projected 1.2 mi (2 km) of pipeline (based on 

historic loss rates) are expected from a proposed action. This represents approximately 

0.19 percent of the total land loss estimated to occur along the Louisiana coast in 1 year (Couvillion 

et al., 2011). This estimate does not take into account mitigating measures from the present 

regulatory programs of Federal or State agencies, modern installation techniques, and the Federal 

“no net loss” policy. These programs and techniques include compensatory mitigations and less 

destructive construction methods among others. Because of the regulations and new construction 

methods, and the limited projection for, at most, one new pipeline landfall, pipeline emplacement 

would be expected to result in zero to negligible impacts to estuarine habitats.
Description of the Affected Environment and Impact Analysis 4-77

Five pipeline installation techniques are used throughout the coastal zone of the Gulf of 

Mexico: upland trenching; jetting; building flotation canals; push-pull ditching; and directional drilling. 

Of these, flotation canals have the most harmful effects. Push-pull ditching can also be used to 

effectively minimize wetland impacts when postconstruction mitigation methods such as backfilling 

are used (Johnston et al., 2009). Trenchless, or directional drilling, is the newest and favored 

technique in sensitive habitats. This technique is considered to be extremely protective of sensitive 

habitats. At present, directional drilling is required almost without exception for crossing barrier 

island and shore faces. Impacts are limited to the access and staging sites for the equipment. By 

using directional drilling, pipeline installation can occur without having to cut through shore facings, 

minimizing any erosion and surface habitat disturbance.

Because of the modern installation techniques and mitigations, the small number of 

projected pipeline landfalls, and the present regulatory programs of the COE and the Gulf Coast 

States, impacts to wetlands and other estuarine areas from pipeline emplacement associated with a 

proposed lease sale are expected to be negligible. 

Dredging

Maintenance dredging of navigation channels and canals is expected to occur with minimal 

impacts to wetlands. It is assumed that the need for maintenance dredging is proportional to the 

percentage of the vessel traffic; therefore, a proposed lease sale is expected to only contribute 

minimally to the need for this dredging, accounting for less than 2 percent, of all traffic using 

navigation channels in the GOM (Chapter 3.1.3.3.4; Tables 3-2 and 3-7). Thus, vessel traffic 

related to a proposed action is only a small portion of the traffic that would require maintenance 

dredging of channels. However, occasionally a channel would be dredged ahead of its normal 

maintenance schedule in order to accommodate the transport of large OCS platforms.

Beneficial use of dredged material can be used to enhance and create coastal wetlands after 

material has been tested for the presence of contaminants. The COE’s New Orleans District 

annually removes approximately 46-53 million m3 (60-70 million yd3

) of dredged material from 

10 Federal navigation channels throughout coastal Louisiana, and approximately 26 percent of this 

material is used for coastal wetland restoration projects (Creef, official communication, 2011). As a 

result of the tremendous wetlands land loss in the Louisiana coastal region, the beneficial use of 

dredged material is expected to increase. Executive Order 11990 (1977) requires that, where 

appropriate, material from maintenance dredging be considered for use as a sediment supplement in 

deteriorating wetland areas to enhance and increase wetland acreage. Given the COE‘s policy of 

beneficial use of dredged material, increased emphasis has been placed on the use of dredged 

material for marsh creation.

Despite the beneficial uses described above, dredging and dredged-material disposal can 

also be detrimental to coastal environments and associated fish and wildlife that use the affected 

areas for nursery grounds and protection. These impacts may include increased erosion rates, 

removal of sediments, increased turbidity, and changes in salinity (Onuf, 1996; Kenworthy and 
4-78 Gulf of Mexico Multisale EIS

Fonseca, 1996; Erftemeijer and Lewis, 2006). Many of these impacts are reduced through the use 

of modern disposal practices.

Because of the mitigations and regulations connected with coastal dredging operations, the 

impacts outlined above are expected to only occur in localized areas over a short amount of time; 

therefore, the overall level of impact to coastal communities is minor. Due to the small contribution 

of a proposed action to the need for dredging, impacts to coastal habitats from a proposed action are 

expected to be negligible to minor. 

Navigation Channels and Vessel Traffic

Most navigation channels projected to be used to support a proposed action are currently 

used by vessels that support the OCS Program (Chapter 3.1.3.3.4; Table 3-7). BOEM 

conservatively estimates that there are approximately 3,013 mi (4,850 km) of Federal navigation 

channels, bayous, and rivers potentially exposed to OCS oil- and gas-related traffic (Table 3-7) in 

the GOM. Of that total, approximately 1,988 mi (3,200 km) of existing OCS oil- and gas-related

navigation canals, bayous, and rivers pass through wetlands, as opposed to passing through large 

bays, sounds, and lagoons. No new navigation channels are expected as a result of a proposed 

action, although channels within ports may be created or enlarged. Ports that have navigation 

channels deep enough to accommodate deeper-draft vessels may expand their infrastructure for 

better accommodation. An example of a significant expansion of a service base is Port Fourchon in 

coastal Louisiana. Port Fourchon has deepened the existing channel and has dredged additional 

new channels to facilitate the expansion. Port Fourchon currently services approximately 90 percent 

of all deepwater rigs and platforms in the GOM (Loren C. Scott and Associates, 2008), and 

approximately half of all offshore service vessel trips from 2012 through 2017 are expected to 

emanate from there (Kaiser, 2015b).

Vessel traffic that may support a proposed action is discussed in Chapter 3.1.4.3. Waves 

generated by boats, ships, barges, and other vessels erode unprotected shorelines and accelerate 

erosion in areas already affected by natural erosion processes. Much of the service-vessel traffic 

that is a necessary component of OCS oil- and gas-related activities uses the channels and canals 

along the Louisiana coast. The most heavily used OCS navigation channel is the channel from Port 

Fourchon to the GOM, which is heavily armored and is less erodible. However, some of this traffic 

may also use Bayou Lafourche from Leeville to Port Fourchon, which is not armored. Recent 

studies have found that armored canals have reduced loss rates compared with unarmored canals 

(Johnston et al., 2009; Thatcher et al., 2011) and that widening rates have slowed based on 

maintenance techniques. A recent BOEM and USGS-funded study (Thatcher et al., 2011) examined 

the susceptibility to erosion of navigation channels based on cover and substrate. They found that 

canal erosion rates have slowed in recent years. Indirect impacts from wake erosion and saltwater 

intrusion are expected to result in minor impacts, which are indistinguishable from direct impacts 

from inshore activities.
Description of the Affected Environment and Impact Analysis 4-79

A proposed action is estimated to contribute <2 percent of the total traffic from 2017 through 

2066. Further details concerning vessel traffic can be found in Chapter 3.1.4.3. Navigation 

channels projected to be used in support of a proposed action are discussed in Chapter 3.1.3.3.4. 

According to BOEM’s calculations, all estimated navigational use (both OCS and other) is expected 

to contribute approximately 336 ha/yr (831 ac/yr) of land loss per year. A proposed action accounts 

for a relatively small percentage of vessel traffic, and ongoing armoring and regular maintenance 

along the waterways tends to reduce erosion. However, BOEM’s estimates of land loss due to a 

proposed action range from 28 to 350 ha (~70 to 860 ac) over 70 years. Therefore, minor to 

moderate impacts related to the vessel traffic would result from a proposed action.

Disposal of OCS-Related Wastes

Produced sands, oil-based or synthetic-based drilling muds and cuttings, along with fluids 

from well treatment, workover, and completion activities, would be transported to shore for disposal 

(Chapter 3.1.5). Sufficient disposal capacity is expected to be available in support of a proposed 

action (Chapter 3.1.7.2.6). Produced-water discharges from OCS wells would be too distant from 

coastal habitats to have anything more than negligible impacts. Because of wetland-protection 

regulations, no new waste disposal sites are expected to be developed in wetlands. Some seepage 

or discharges from existing waste sites into adjacent wetland areas may occur and toxic wastes

could kill wetland plants, but such seepage resulting from a proposed action is expected to be 

negligible. 

Onshore Facilities

Various kinds of onshore facilities service OCS development. All projected new facilities that 

are attributed to the OCS Program and a proposed action are described in Chapter 3.1.7. State and 

Federal permitting agencies discourage the placement of new facilities and the expansion of existing 

facilities in wetlands. However, any large construction project in the coastal zone is likely to impact 

some wetland acreage. Any impacts upon wetlands are mitigated in accordance with the Clean 

Water Act requirements and the COE’s 404 permit and State permitting programs. The high cost of 

wetland mitigation discourages industry from causing damage to wetlands when building onshore 

facilities. Since no new facilities are estimated with a proposed action and any possible impacts 

would be mitigated, the impact level from the associated factors discussed above would be 

negligible. 

4.3.1.2.2 Accidental Events

A detailed description of the impact-producing factors and scenario for accidental events 

from a proposed action are given in Chapter 3.2. There is also a risk analysis of oil spills in Chapter 

3.2.1. The main impact-producing factors that would affect wetlands are oil spills. Chemical spills 

could also potentially affect wetlands, but they are rare (Table 3-21).

Both coastal and offshore oil spills can be caused by large tropical storm events, faulty 

equipment, or human error. The degree of coastal impact is a function of many factors, including the 
4-80 Gulf of Mexico Multisale EIS

source oil type, volume, and condition of the oil as it reaches shore, along with the season of the spill 

and the composition of the wetland plant community affected. Barrier island loss due to hurricanes

and anthropogenic factors has reduced protection of wetlands from offshore oil spills, and thus, there 

is a greater potential for the oiling of coastal wetlands during an accidental event. Refer to the 

Catastrophic Spill Event Analysis white paper for an analysis of impacts from a low-probability 

catastrophic spill event (USDOI, BOEM, 2017).

Primary Impacts of Oil Spills

The geopraphic distribution of OCS oil- and gas-related activity reduces the probability of 

unweathered oil reaching coastal wetlands. The OCS production facilities are located at least 3 nmi 

(3.5 mi; 5.6 km) from coastal wetlands, and much of the OCS oil- and gas-related activity is much 

farther. Recent trends towards drilling in deeper water have increased the proportion of OCS 

oil- and gas-related activity in distant locations, many of which are well over 100 nmi (115 mi; 

185 km) offshore. This allows for the toxicity of spilled oil from offshore to be greatly reduced or 

eliminated by weathering and biodegradation (OSAT-2, 2011).

Coastal Spills 

The greatest threat to estuarine habitat with regards to an oil spill is from a coastal spill 

resulting from a vessel accident or pipeline rupture. These spills are a concern since they would be 

much closer to the estuarine resources. Resulting contact would likely be greater, and toxicity would 

tend to be greater due to reduced weathering of the oil. While a resulting slick may cause impacts to 

estuarine habitat, the cleanup effort (i.e., equipment, chemicals, and personnel) can generate 

additional impacts to the area. Associated foot and vehicular traffic may work oil farther into the 

sediment than would otherwise occur. Further, physical prevention methods such as booms, barrier 

berms, and diversions can alter hydrology, specifically changing salinity and water clarity. These 

changes could cause mortality or reduced productivity in certain species of submerged vegetation

because they are only tolerant to certain salinities and light levels (Zieman et al., 1984; Kenworthy 

and Fonesca, 1996; Frazer et al., 2006). Close monitoring and restrictions on the use of bottomdisturbing equipment would be needed to avoid or minimize those impacts.

Numerous investigators have studied the immediate impacts of oil spills on GOM coastal 

habitats and elsewhere. Often, seemingly contradictory conclusions are generated from these 

impact assessments. These contradictions can be explained by differences in parameters, including 

oil concentrations and chemical composition, season or weather, vegetation type and density, 

whether the area is in a low- or high-energy environment, preexisting stress level on the vegetation, 

soil types, anoxic condition of the soil, and water levels. Data indicate that vegetation that is lightly 

oiled would experience plant die-back, followed by recovery without replanting; therefore, most 

impacts from light oiling to vegetation are considered to be short term and reversible (Lytle, 1975; 

DeLaune et al., 1979; Webb et al., 1985). However, Alexander and Webb (1987) noted erosion of 

the shoreline in areas affected with high oil content and Fischel et al. (1989) found that, while some 

oiled marsh areas showed recovery of vegetation a year after a spill, other areas had converted to 

mud flats or open water.
Description of the Affected Environment and Impact Analysis 4-81

Oil has been found or estimated to persist for at least 17-20 years in low-energy 

environments like salt marshes (Teal et al., 1992; Baker et al., 1993; Burns et al., 1993; Irvine, 

2000). If thick oil is deposited on marsh in low-energy environments, effects on marsh vegetation 

can be severe and recovery can take decades (Baca et al., 1987; Baker et al., 1993). The sediment 

type, the anoxic condition of the soils, and whether the area is in a low- or high-energy environment 

all play a part in the persistence of oil in marsh sediment (Teal and Howarth, 1984), so different 

shorelines exhibit varying levels of oil persistence (Hayes et al., 1980; Irvine, 2000). Oil is more 

persistent in anoxic sediments and, as a result of this longer residence time, has the potential to do 

damage to both marsh vegetation and associated benthic species. Batubara et al. (2014) found that 

PAH degradation is higher in intertidal than in subtidal wetland soils. For submerged vegetation the 

same is true, and oil can cause decreased water clarity from coating, and shading could cause 

reduced chlorophyll production and could lead to a decrease in vegetation (Erftemeijer and Lewis, 

2006).

Cleanup activities in marshes that can last years to decades following a spill may accelerate 

erosion rates and retard recovery rates. While oil can completely foul wetland plants, it is the 

amount and type of oil, as well as the particular plant that determines recovery. Pezeshki et al. 

(2000) found that Louisiana crude oil was less damaging and fatal to Spartina alterniflora marsh 

grass than the heavier crudes. Heavy oiling can stop photosynthetic activity, but the S. alterniflora

produced additional leaves and was able to recover without shoreline cleanup. Except in areas of 

heavy oiling, it is better to let wetland areas recover naturally (Zengel et al., 2014).

Numerous studies have demonstrated that different species of plants respond differently to 

oiling. Lin and Mendelssohn (1996) found that Louisiana crude oil applied to three species of marsh 

plants resulted in no regrowth after 1 year in applications for Spartina alterniflora and S. patens, but 

resulted in increased regrowth with increased oil application for Sagittaria lancifolia. Kokaly et al. 

(2011) found that, where the predominant marsh grass is tall (Phragmites australis) and less 

susceptible to being completely oiled, damage is minimized. Judy et al. (2014) also found high 

tolerance of P. australis to weathered and emulsified oil. Coastal marshes impacted by crude oil 

were observed to show evidence of recovery within 1 year after oil was stranded and covered 

vegetation, with shoot production observed in heavily oiled areas, although depending on vegetation 

type, the amount of recovery varied (Delaune and Wright, 2011). When a spill contacts wetlands, 

one impact from the resulting depletion of marsh vegetation is increased and accelerated erosion, 

and resulting land loss (Alexander and Webb, 1987). Other studies documented increased erosion 

at highly oiled sites 26 months after a spill (McClenachan et al., 2013), and oiled islands were found 

to have greatly increased the rates of erosion, which were 200 percent of the rates of unoiled islands 

for the first 2.5 years after the oiling (Turner et al., 2016).

Some OCS oil- and gas-related pipelines traverse wetland areas, and pipeline accidents 

could result in high concentrations of oil directly contacting localized areas of wetland habitats 

(Fischel et al., 1989). In a study of a coastal pipeline break by Mendelssohn et al. (1993), a 300-bbl 

spill of Louisiana crude oil impacted 49 ac (20 ha) of wetlands, resulting in considerable short-term 

effects on the brackish marsh community. While considerable die out of the marsh was noted, 
4-82 Gulf of Mexico Multisale EIS

recovery of the marsh was complete within 5 years despite the residual hydrocarbons that were 

found in the marsh sediment. The study also noted that the health of the recolonizing vegetation 

was not significantly different from the health of vegetation found in the areas that were not oiled. 

Patterns of land loss were spatially variable, but the rate of loss in the oiled areas was similar to that 

of the unaffected areas (Mendelssohn et al., 1993).

BOEM’s analysis shows that 96 percent of reasonably foreseeable spills from OCS oil-and 

gas-related activity are <1 bbl, with an average size of <0.05 bbl (Anderson et al., 2012). Because 

of the small contribution to all such spills from a proposed action, the small size of most spills, and 

with current safety measures and cleanup guidance in place, the impacts from the impact-producing 

factors of a coastal spill are expected to be minor for estuarine communities.

Offshore Spills 

The probabilities of an offshore spill ≥1,000 bbl occurring and contacting environmental 

features are described in Chapter 3.2.1.4.8. In addition, the results of a risk analysis estimating the 

likelihood of a spill <1,000 bbl occurring and contacting environmental resources (including 

wetlands) can be found in Chapter 3.2.1.6.2. Most spills from the OCS are likely to be distant 

enough that, should a slick from such a spill make landfall, the volume of oil remaining in the slick is 

expected to be small. This is because the distance of the spill to the coast allows oil to evaporate, 

break down, and disperse. Also, due to the tidal flushing on the coast, a slick would be broken down 

further. However, should spills from the OCS occur proximate to State waters, they could reach 

shore before much weathering, evaporation, or dispersal had occurred. The probabilities of oil spills 

≥1,000 bbl occurring and contacting coastal shorelines varies by location, with the highest probability 

as a result of a proposed action estimated at 8 percent for one location; for most locations, it was 

<0.5-1 percent (Figure E-20).

Because of the small contribution to all such spills from a proposed action, the distance from 

coastal communities, improved technologies, and the dynamic nature of the coastal environment, 

offshore spills are expected to have a minor impact on the estuarine community.

Spills that occur in or near Chandeleur Sound or Mississippi Sound could affect estuarine 

habitat in the Gulf Islands National Seashore (135,458 ac; 545,818 ha), including its Wilderness 

Area (4,080 ac; 1,651 ha), and the Breton National Wildlife Refuge (18,273 ac; 7,395 ha) with its 

Wilderness Area (5,000 ac; 2,023 ha). Although the wetland acreage on these islands is small, the 

wetlands and associated communities make up an important element in the habitat of the islands. 

The inlets that connect Mississippi Sound with the marsh-fringed estuaries and lagoons within the 

islands are narrow; therefore, a small percentage of the oil that contacts the Sound side of the 

islands would be carried by the tides into interior lagoons.

Secondary Impacts of Oil Spills

The short-term effects of oil on wetland plants range from reduction in transpiration and 

carbon fixation to plant mortality. Depending on the type and quantity of oil in the sediment, 
Description of the Affected Environment and Impact Analysis 4-83

mineralization of nutrients can be blocked so that there is less nutrient uptake from the soils. The 

potential impact of the oiling on the wetland habitats is dependent on several factors, including 

season. In general, most wetland plants are more susceptible to impacts from oiling during the 

growing season. Heavy oil causes mortality by coating gas exchange surfaces on the plants and by 

sealing sediment, which limits nutrient exchange to below-ground tissue. Light weight oils have 

been found to be more toxic to various marsh plants and associated organisms because the oil 

alters membrane permeability and disrupts metabolism (Pezeshki et al., 2000). Due to the 

difference in oil tolerances of various wetland plants, changes in species composition may be 

evident as a secondary impact of the spill (Pezeshki et al., 2000). Studies indicated that some 

dominant freshwater marsh species (Sagittaria lancifolia) are tolerant to oil fouling and may recover 

without being cleaned (Lin and Mendelssohn, 1996). Secondary impacts can also include impacts 

caused by cleanup activities, as discussed below. Because these secondary impacts would not 

noticeably affect GOM coastal plant communities as a whole, impacts are expected to be minor. 

Cleanup Activities

Current methods to clean up oil spills include mechanical removal, in-situ burning, and 

bioremediation (refer to Chapter 3.2.8 for more information). Generally speaking, unless the oiling 

is extremely heavy, the best approach has been to avoid measures that would further drive oil into 

the sediment (e.g., vessel and foot traffic) or damage vegetation. Often that means it is best to do 

nothing and let nature take its course. Oil spill cleanup in coastal marshes remains a problematic 

issue because wetlands and submerged vegetation can be extremely sensitive to the disturbances 

associated with cleanup activities. Once a marsh is impacted by an oil spill, a decision must be 

made concerning the best method of clean up and restoration. Often the best course of action is to 

let the impacted area(s) recover naturally in order to avoid secondary impacts associated with the 

cleanup process, such as trampling vegetation, accelerating erosion, and burying oil (Zengel and 

Michel, 2013; Long and Vandermeulen, 1983: Getter et al., 1984; Mendelssohn et al., 1993). In 

areas of thick oil deposits, however, a cleanup effort would result in greater recovery (Baker et al., 

1993). Because oil spills that require cleanup can have noticeable but localized impacts, cleanup 

activities are expected to have a minor effect on the estuarine community.

Trash and Debris

Trash and debris can be an issue for estuarine communities in that the fauna in these areas 

could ingest or become entangled in the trash and debris. BOEM and BSEE have addressed the 

marine debris issue by imposing marine debris awareness and prevention measures on the oil and 

gas industry through NTL 2015-BSEE-G03, which provides guidance to the industry operators 

regarding dumping trash and debris into the marine environment and informs operators of 

regulations set by other regulatory agencies (i.e., USEPA and USCG). Because of the mitigations

and awareness, OCS oil- and gas-related trash and debris from a proposed action would result in 

negligible impacts to estuarine habitat.
4-84 Gulf of Mexico Multisale EIS

4.3.1.2.3 Cumulative Impacts

Estuarine habitats are vulnerable to many impact-producing factors from OCS oil- and 

gas-related and non-OCS oil- and gas-related impacts. Specific OCS oil- and gas-related, 

impact-producing factors considered in this cumulative analysis include the following: (1) oil spills; 

(2) OCS oil- and gas-related vessel traffic and navigation canals; (3) construction of OCS oil- and 

gas-related infrastructure and support structure (including pipelines); and (4) waste disposal. 

Non-OCS oil and gas-related, impact-producing factors would potentially impact wetland resources, 

including the following: (1) State oil and gas activities; (2) non-OCS oil- and gas-related vessel 

traffic and navigation canals; (3) coastal infrastructure and development; (4) natural processes 

(including hurricanes and subsidence); and (5) sea-level rise (natural causes of subsidence are 

combined with subsidence caused by extraction and other man made alterations). While each of 

these factors can cause negative impacts to wetlands, a proposed action would not greatly increase 

the overall impacts.

OCS Oil- and Gas-Related Impacts

Oil Spills

The potential for coastal oil spills poses a threat for coastal habitats due to the proximity of 

the spills to these vegetated areas. Aging infrastructure including refineries, onshore production 

facilities, platforms, and pipelines would continue to be an increasing source of potential spills, but 

future spills from these types of facilities would be less likely because these older facilities are 

gradually either structurally updated or replaced by the owner/operator. The number and most likely 

spill sizes to occur in coastal waters in the future are expected to resemble the patterns that have 

occurred in the past (not including catastrophic spills), as long as the level of energy-related 

commercial and recreational activities remains the same.

The Deepwater Horizon oil spill was the largest spill ever recorded in the GOM and resulted 

in the oiling of an extensive portion of the northern Gulf Coast shoreline from Texas to northwest 

Florida (Florida Panhandle) (OSAT-2, 2011). This event must be considered in the cumulative 

baseline due to the volume of oil released and the geographic area affected. Oil from the Deepwater 

Horizon explosion and oil spill was documented to have stranded on approximately 687 mi 

(1,105 km) of marsh shoreline (Nixon et al., 2016). In most areas, the oil stranded along the marsh 

edge, usually spreading into the marsh no more than about 33-49 ft (10-15 m) perpendicular to the 

shoreline. In the areas of heaviest oiling, the width of the impacted area was 56.4 ft (17.1 m) (Michel 

et al., 2013a; Deepwater Horizon Natural Resource Damage Assessment Trustees, 2016).

The Trustees, in their recent PDARP/PEIS (Deepwater Horizon Natural Resource Damage 

Assessment Trustees, 2016), documented reduced vegetative cover and vegetated (aboveground) 

biomass, and an increase in marsh edge erosion as a result of the Deepwater Horizon oil spill. The 

Deepwater Horizon oil spill resulted in increased rates of coastal erosion, and erosion rates 

approximately doubled along at least 108 mi (174 km) of shoreline over at least 3 years. These 

results are similar to the findings from the previous Deepwater Horizon studies summarized above.
Description of the Affected Environment and Impact Analysis 4-85

The Trustees’ PDARP/PEIS also documented injury to wetlands caused by spill response, 

including the following:

• more than 497 mi (800 km) of boom was stranded in marshes, injuring vegetation 

and birds;

• the removal of stranded boom also affected the wetlands, i.e., vegetation was 

crushed by airboats, walking boards, foot traffic, and the dragging of the boom 

across the wetland surface;

• the footprint of stranded boom totaled approximately 52 ac (21 ha; 0.08 mi2 or 

0.21 km2

), which does not include the greater area of wetland swept by the boom 

when it was moved by storm waves. (Deepwater Horizon Natural Resource 

Damage Assessment Trustees, 2016); and

• submerged aquatic vegetation habitats were lost from oiling and from physical 

disturbance as part of response actions. Chandeleur Islands’ submerged aquatic 

vegetation, which is uniquely valuable in the region, was particularly affected, 

with more than 270 ac (109 ha) of seagrass destroyed. Injuries to submerged 

aquatic vegetation habitats were also documented within the boundaries of the 

Gulf Islands National Seashore and in Jean Lafitte National Historical Park and 

Preserve (Deepwater Horizon Natural Resource Damage Assessment Trustees, 

2016).

Cleanup activities were conducted on 8.9 percent of the affected marsh. The most heavily 

oiled marshes in Barataria Bay, Louisiana, were cleaned using intensive manual and mechanical 

raking and cutting methods (Michel et al., 2013a). This oil and the associated cleanup activities 

have impacted wetlands in Louisiana, Mississippi, Alabama, and the panhandle of Florida. While 

there were localized severe impacts to wetlands, many of the areas affected have recovered or 

show a moderate level of impact. The oil was released and treated in deep water nearly 48 mi 

(77 km) from shore. This contributed to the weathering and detoxification of the oil that reached the 

shoreline. It is too early to determine the cumulative long-term effect of this spill and its contribution 

to the ongoing marsh loss or the acceleration of that loss. New regulations focusing on improved 

safety, more regulatory checks, and inspections should decrease the already small likelihood of the 

occurrence of such spills, which are not part of a proposed action and not reasonably expected to 

occur. Potential impacts as a result of a low-probability catastrophic event are discussed in the 

Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017).

Oil from offshore spills is less likely to reach the estuarine habitat in the same condition it 

was released due to weathering, potential dispersant treatment, and blockage by barrier islands and 

shorelines. However, erosion of these barriers by hurricanes and tropical storms has decreased the 

level of protection afforded the mainland, so flood tides could bring oil through tidal inlets (USDOC, 

NMFS, 2007a). For many spills, light oiling of vegetated wetlands may occur. Adverse impacts from 

light oiling that may occur to wetland plants are expected to be short lived, with possible plant die-
4-86 Gulf of Mexico Multisale EIS

back, followed by recovery without replanting (Lytle, 1975; DeLaune et al., 1979; Webb et al., 1985). 

However, spill data from the OCS show that, over decades of activity, tens of thousands of barrels of 

oil have been spilled (Chapter 3.2.1.1.3), not including oil from the Deepwater Horizon oil spill. 

Cumulative OCS oil- and-gas-related spills resulting from all past and present leasing activities are 

estimated to have a major impact on the estuarine community. The incremental contribution of a 

proposed action, however, to the impacts of cumulative OCS oil- and gas-related spills are expected 

to be minor due to the small contribution to all such spills from a proposed action, the small size of 

most spills, the distance from estuarine communities, improved technologies, and the dynamic 

nature of the coastal environment.

Vessel Traffic

Navigation channels in the coastal areas of the GOM support both OCS oil- and gas-related 

and non-OCS oil- and gas-related vessel traffic. Waves generated by boats, ships, barges, and 

other vessels erode unprotected shorelines and accelerate erosion in areas already affected by the 

natural erosion process. BOEM conservatively estimates that there are approximately 3,013 mi 

(4,850 km) of Federal navigation channels, bayous, and rivers potentially exposed to OCS oil- and 

gas-related traffic (Table 3-7) in the GOM. Conservative estimates show that land loss in Federal 

navigation channels over the next 70 years from various activities (non-OCS oil- and gas-related and 

OCS oil- and gas-related) could total approximately 58,000 ac (24,000 ha), while land loss from 

cumulative OCS oil- and gas-related activities could total approximately 4,500-14,000 ac 

(1,800-5,500 ha). Adjusted for the approximately 30 percent of channel length that is armored, 

which greatly reduces erosion, this land loss could total approximately 3,100-9,500 ac 

(1,300-3,900 ha). This number is considered conservative because open waterways were included 

in the total length of Federal navigation channels, vessel size was not taken into consideration, and 

there are sources of erosion to navigation canals other than vessel traffic alone. In addition, 

approximately half of all offshore service vessel trips from 2017 through 2022 are expected to 

originate from Port Fourchon, Louisiana (Kaiser, 2015b), and the channel from the Gulf to Port 

Fourchon is mostly armored, reducing channel widening. If this reliance on Port Fourchon 

continues, the land loss related to OCS channel use would be less than that estimated above. 

However, as noted above, some of this traffic may also use Bayou Lafourche from Leeville to Port 

Fourchon, which is not armored.

Coastal wetland loss is greatest in Louisiana. In the Louisiana Coastal Master Plan (State of 

Louisiana, Coastal Protection and Restoration Authority, 2012), it is estimated that up to 1,750 mi2

(4,500 km2

) of land would be lost in the next 50 years. Using BOEM’s conservative estimates of 

waterways exposed to OCS traffic in the Louisiana Coastal Area (LCA) and the average canal 

widening rate, and comparing those data to estimated land loss in Louisiana over the next 50 years, 

BOEM estimates that approximately 3.7 percent of the total land loss in Louisiana would occur due 

to saltwater intrusion, hurricanes, and vessel traffic (OCS oil- and gas-related and non-OCS oil- and 

gas-related) in navigation canals. Because OCS oil- and gas-related vessel traffic constitutes only 

9-27 percent of the total vessel traffic in the GOM, BOEM conservatively estimates that OCS oil- and 
Description of the Affected Environment and Impact Analysis 4-87

gas-related vessel traffic could contribute approximately 1 percent or less of the land loss in coastal 

Louisiana in the next 70 years.

The OCS oil- and gas-related vessel traffic associated with the increased number of offshore 

platforms is expected to contribute minimally to the need for maintenance dredging activity of 

navigation canals. The primary support, transfer, and production facilities used for OCS oil- and 

gas-related activities are located along armored canals and waterways, thus minimizing marsh loss. 

If new onshore transfer or production facilities would be constructed, access channels may have to 

be dredged. In the foreseeable future, there would be a continuing need for dredged material for 

coastal restoration, wetland creation, and to some extent, offshore sediments (e.g., sand, etc.) 

needed for beach restoration and hurricane protection. Alternative dredged-material disposal 

methods can be beneficially used for wetland creation or restoration as required by the COE’s 

permitting program.

A proposed action would result in a small incremental increase in cumulative impacts to 

coastal wetlands associated with OCS oil- and gas-related vessel traffic, and these impacts are 

offset by the benefits of wetland creation using dredged material from navigation channels. 

However, due to the permanent loss of hundreds of acres of wetlands, impacts of a proposed action 

are expected to be moderate. 

Coastal Infrastructure and Pipelines

Projected new facilities that are attributed to the OCS Program and a proposed lease sale 

would not be primarily in wetland areas, and no additional service bases, heliports, platform 

fabrication yards, shipyards, pipe-coating facilities, or refineries are expected (Chapter 3.3.1.10). 

State and Federal permitting agencies discourage the placement of new facilities or expansion of 

existing facilities in wetlands. However, any sizable coastal facility may have construction impacts in 

wetlands. Any localized impacts upon wetlands from existing facilities are expected to be mitigated 

because of the Clean Water Act permitting requirements.

BOEM projects 0-1 new gas processing facilities and 0-1 new pipeline landfalls for a 

proposed action. A more detailed description of coastal infrastructure is provided in Chapter 4.14.1. 

If a new facility is constructed and a pipeline makes landfall, any impacts upon wetlands would be 

mitigated in accordance with the Clean Water Act requirements and the COE’s 404 permit and State 

permitting programs. These mitigations and regulatory requirements, such as avoidance and 

compensatory wetland mitigation, would result in negligible impacts to coastal habitats.

Several methods exist to further reduce the number of new pipeline landfalls and their 

cumulative impact, e.g., the addition of corrosion preventatives to the pipeline itself (reducing the 

probability of accidental leakage from aging pipelines), in combination with “tie ins” to existing 

Federal or State pipelines with shore connections. While impacts are greatly reduced by mitigation

techniques, existing pipelines were placed using older techniques and have caused, and would 

continue to cause, impacts to adjacent wetlands. Remaining impacts may include expansion of tidal 
4-88 Gulf of Mexico Multisale EIS

influence, saltwater intrusion, hydrodynamic alterations, erosion, sediment transport, and habitat 

conversion (Cox et al., 1997; Morton, 2003; Ko and Day, 2004b). Pipeline maintenance activities 

that disturb wetlands are very infrequent and are mitigated through regulatory programs, including 

review by the State of Louisiana through its coastal use permit requirements and through the Clean 

Water Act Section 404 and Rivers and Harbors Act Section 10 permits.

The continued widening of OCS pipeline canals from erosion does not appear to be an 

important factor contributing to OCS oil- and gas-related direct land loss. This is because few 

pipelines are open to navigation and the impact width of these pipelines does not appear to be 

significantly different from that for pipelines closed to navigation. Based on the projected coastal 

Louisiana wetlands over 50 years (Couvillion et al., 2013), land loss resulting from new OCS pipeline 

construction represents <1 percent of the total expected loss. This estimate does not take into 

account the present regulatory programs and modern installation techniques that would be expected 

to further mitigate this potential impact. Throughout the 50-year life of a proposed lease sale, a 

majority of the already old pipeline distribution and production systems would continue to age. This 

could result in an increasingly large inventory of pipelines and support structures that would need to 

be replaced or repaired. The replacement and repair of the pipeline system may temporarily impact 

wetlands in the pipeline corridors, as crews could trample wetland plants or access would have to be 

dredged; however, if proper mitigation is implemented and maintained, impacts should be minimal 

and temporary. In the absence of the replacement of these aging pipelines, the potential risk for 

spills and leaks would increase in coastal and offshore waters. Because of the mitigations and 

regulations connected with coastal operations, the impacts outlined above are expected to only 

occur in localized areas over a short amount of time and, therefore, the overall level of impact to 

estuarine communities is minor. 

Waste Disposal

Discharge of OCS oil- and gas-related produced water is generally into offshore Gulf waters 

in accordance with NPDES permits or injected back down into wells; therefore, produced waters

from the OCS are not expected to affect coastal wetlands (Chapter 3.3.1.8). Produced sands, oilbased or synthetic-based drilling muds and cuttings, along with fluids from well treatment, workover, 

and completion activities from OCS wells, would be transported to shore for disposal in existing 

disposal facilities approved by the USEPA for handling these materials. Because of wetlandprotection regulations, no new waste disposal site would be developed in wetlands. Some seepage 

from waste sites into adjacent wetland areas may occur and result in damage to wetland vegetation 

ranging from sublethal effects to mortality, depending on the toxicity of the waste.

Trash and debris can potentially impact coastal estuarine communities in that the fauna in 

these areas could ingest or become entangled in the trash and debris. BOEM and BSEE have 

addressed the marine debris issue by imposing marine debris awareness and prevention measures 

on the oil and gas industry through NTL 2015-BSEE-G03, as noted above. Past and present OCS 

oil- and gas-related activity has been the source of trash and debris that finds its way into coastal 

areas, resulting in minor to moderate impacts to estuarine habitat. However, due to the small 
Description of the Affected Environment and Impact Analysis 4-89

contribution of a proposed action to OCS oil- and gas-related activity, trash and debris from a 

proposed action would result in negligible to minor impacts to estuarine habitat.

Non-OCS Oil- and Gas-Related Impacts

State Oil and Gas

Impacts are expected to occur as a result of oil spills, dredging for new pipeline canals, 

maintenance, and usage of existing rig access canals and drill slips, and for the preparation of new 

well sites related to State oil and gas activities (Chapter 3.3.2.1). Such activity has taken a 

tremendous toll on coastal wetlands, particularly in Louisiana (Turner et al., 1994). Many pipelines 

carry product from both OCS oil- and gas-related and non-OCS oil- and gas-related sources. The 

impacts from these activities are generally the same as those described in the “Routine Activities,” 

“Accidental Events,” and “OCS Oil- and Gas-Related Impacts” sections above, although these 

impacts may be more pronounced due to the proximity of oil and gas activities on State lands to 

wetlands. Another impact from State oil and gas activity is local subsidence. This subsidence may 

be due to the extraction of large volumes of oil and gas, sulfur, and salt from subsurface reservoirs 

(Morton, 2003; Morton et al., 2002 and 2005), but subsidence associated with this factor seems to 

have slowed greatly over the last three decades as the reservoirs are depleted. Subsidence leads to 

the drowning of marsh plants and conversion to open water. Because of the continued effects of the 

extensive dredging of canals through coastal wetlands, impacts from State oil and gas activities are 

expected to be major. 

Vessel Traffic and Navigation Canals

Non-OCS oil- and gas-related vessel traffic in the GOM includes commercial shipping, 

support for State oil and gas activities, commercial and recreational fishing vessels, pleasure 

boating, and other types of traffic (Chapter 3.3.2.2). Waves generated by boats, ships, barges, and 

other vessels erode unprotected shorelines and accelerate erosion in areas already affected by the 

natural erosion process. In many cases, this erosion results in wetland loss. Submerged vegetation

communities can be damaged by boat anchors, keels, and propellers, and by activities such as 

trampling, trawling, and State oil- and gas-related or scientific seismic surveys (Sargent et al., 1995; 

Dunton et al., 1998). Navigation channels require routine maintenance dredging. Minor adverse 

impacts on wetlands from maintenance dredging are expected because the large majority of the 

material would be either used to enhance or create marsh, or disposed upon existing disposal areas.

Net land loss due to navigation canals alone can be calculated by comparing erosion rates 

with beneficial activities such as land gained through the use of dredged sands; refer to the 

estimates in “OCS Oil- and Gas-Related Impacts” section above.

Wetland losses may be generated by the secondary impacts of saltwater intrusion, flank 

subsidence, freshwater-reservoir reduction, and deeper tidal penetration. Navigation channels 

contribute to the negative impacts from saltwater intrusion (Gosselink et al., 1979; Wang, 1987). 

Wang (1987) developed a model demonstrating that, under certain environmental conditions, 
4-90 Gulf of Mexico Multisale EIS

saltwater penetrates farther inland in deep navigation channels than in shallower channels, 

suggesting that navigation channels act as “salt pumps.” This change in salinity results in a 

substantial habitat transition from freshwater to brackish water, then to saltwater, and ultimately to 

open-water systems. An example is the construction of the Mississippi River Gulf Outlet, which 

transformed many of the cypress swamps east of the Mississippi River below New Orleans into open 

water or areas largely composed of marsh vegetation (Spartina spp.) among dead cypress tree 

trunks. This channel was closed in 2009, and further saltwater intrusion through it has been 

curtailed.

Onshore activity that would contribute to wetland loss includes additional construction of 

access channels (for instance at fabrication yards) and onshore construction of new well sites and 

the expansion or construction of onshore production facilities or receiving and transferring facilities. 

Most of these facilities would be located in Louisiana. Management activities, including erosion 

protection and restoration along the edges of these canals, can significantly reduce canal-widening 

impacts on wetland loss (Johnston et al., 2009; Thatcher et al., 2011). Because of the large 

contribution to total vessel traffic from non-OCS oil- and gas-related sources, the secondary impacts 

of navigation canals, such as saltwater intrusion, and the continuing impacts of existing access 

channels, the impacts from non-OCS oil- and gas-related vessel traffic and related activities are 

expected to be major. 

Coastal Infrastructure and Development

The development of estuarine habitat for agricultural, residential, industrial, commercial, and 

silvicultural (forest expansion) uses (Chapter 4.14.1) would continue but with more regulatory and 

planning constraints required under the Clean Water Act and other regulations. Impacts from these 

developments, such as alteration to habitat or hydrology, are expected to continue as development 

in coastal regions around the GOM continues.

Urban and rural development was an important factor in wetland loss in coastal watersheds 

from 1998 through 2004 (Stedman and Dahl, 2008; Dahl and Stedman, 2013). Agricultural, 

residential, industrial, and commercial developments, including recreational and tourist 

developments, have been particularly destructive to coastal wetlands in the GOM by altering habitat 

and hydrology, which can contribute to the loss of wetland ecosystems through mechanisms such as 

the addition of pollutants, creating or widening channels, or physical removal of habitat. Indirect 

effects of such development can include expansion of supporting infrastructure, including roads, 

bridges, and utilities, with related impacts similar to those mentioned above.

Infrastructure that serves the transportation of foreign oil, such as oil ports, can have wetland

impacts to the extent that it is constructed on or adjacent to wetlands. The current regulatory 

programs, modern construction techniques, and mitigations have reduced recent impacts to 

wetlands from pipeline installation. The continued presence of existing pipelines can contribute to 

wetland loss (Johnston et al., 2009). Oil spills caused by leaking or broken pipelines can also impact 

wetlands.
Description of the Affected Environment and Impact Analysis 4-91

Existing regulations and development permitting procedures indicate that developmentrelated wetland loss may be slowed. Between 2004 and 2009, there were very few (<1%) estuarine 

emergent losses attributed to discrete anthropogenic actions that fill or otherwise convert salt marsh 

areas to uplands. This suggests that marine and estuarine vegetated wetlands (tidal salt marsh and 

shrubs) have been afforded protection by various State and Federal coastal regulatory measures 

(Dahl, 2011). Impacts are to some extent offset by coastal restoration programs. Examples of these 

programs are the Coastal Impact Assistance Program (CIAP), the Coastal Wetlands Planning, 

Protection, and Restoration Act (CWPPRA), and the Resources and Ecosystems Sustainability, 

Tourist Opportunities and Revived Economies of the Gulf Coast States Act (RESTORE Act) (refer to 

Chapter 3.3.2.8.3). Although development-related wetland loss may be slowed, cumulative impacts

of past development and related infrastructure are expected to be moderate. 

Sea-Level Rise

There is increasing new evidence of the importance of the effect of sea-level rise (and marsh 

subsidence) as it relates to the loss of marsh or changes in marshes, marsh types, and plant 

diversity (Chapter 3.3.2.8.1; Spalding and Hester, 2007). Spalding and Hester (2007) show that the 

very structure of coastal vegetative communities would likely be altered by sea-level rise because 

community shifts would be governed by the responses of individual species to new environmental 

conditions. This could change the vegetative make up of different estuarine habitats and, in turn, 

could change faunal species presence.

Gulf Coast wetlands tend to occur at low elevations, often between 1 and 2 ft (0.3 and 0.6 m) 

above sea level. For example, if current projections are realized and sea level increases by 3.5 ft 

(1.1 m) in Galveston, Texas, by the year 2100 (USEPA, 2013a), most of Texas’ coastal wetlands 

would be under water well before 2100. A more conservative estimate of sea-level rise, known as 

the AR4 scenario, calls for an increase (globally) of 16 in (41 cm) by 2100 (NRC, 2010). Even this 

rate of increase would be likely to drown large areas of Gulf Coast wetlands, especially when local, 

relative sea-level rise is considered. Since 1870, global sea level has risen by about 8 in (20 cm) 

(USEPA, 2013a). Even at current measured rates of relative sea-level rise, vast areas of Gulf 

coastal wetlands can be expected to convert to open water as low-lying coastal marshes are 

inundated (refer to Chapter 3.3.2.8.1). Impacts to coastal habitats are expected to be major due to 

the large scale of wetland loss from sea-level rise.

Natural Processes

Along with increased human activities, hurricanes and tropical storms in the GOM have 

greatly impacted coastal habitats (Chapter 3.3.2.9). Intense storms can erode all of the vegetation 

and soil from some areas of marsh, leaving behind a body of water. An extreme example occurred 

when hurricanes in 2005 resulted in land loss in Louisiana equivalent to approximately 42 percent of 

the projected total land loss over the next 50 years (Barras et al., 2003; Barras, 2006). These 

storms can also remove or bury submerged beds and the barriers that protect these beds from storm 

surges. This could weaken the existing populations of local submerged vegetation. Seagrass beds 

have been repeatedly damaged from hurricane overwash of barrier islands onto the beds. The 
4-92 Gulf of Mexico Multisale EIS

presence of strong tropical storms is a routine background condition in the GOM that contributes to 

cumulative impacts to wetlands. Natural subsidence has caused wetland loss through compaction 

of Holocene strata (the rocks and deposits from 10,000 years ago to present). Stephens (2010) has 

identified faulting mechanisms in coastal Louisiana that actually may be causing what appears as 

subsidence. Refer to Chapter 3.3.2.8 for more information.

Whether it is from anthropogenic activities or a natural cycle, increased surface water temperature, 

sea levels, and storm events have impacts on seagrass beds by adding stress (e.g., burial, salinity 

changes, turbidity changes etc.) to this sensitive and already stressed ecosystem (Orth et al., 2006). 

Impacts to estuarine habitats are expected to be major because of the large scale of wetland loss 

from hurricanes and subsidence added to the ongoing stress these communities endure.

Mississippi River Hydromodification

With the construction of levees, dams, and other flood control structures along the 

Mississippi River, some of the natural processes that built the coastal Louisiana delta have been 

prevented, which has had serious impacts (Chapter 3.3.2.10). Beneficially, the hydromodification 

has allowed human settlement and development in coastal areas of Louisiana while also providing a 

stable navigation channel. However, by channelizing the river, it is prevented from flooding and 

distributing sediments that can build wetlands and counteract the effects of sea-level rise (Yuill et al., 

2009). When the Mississippi River floods, it brings nutrient-rich water and alluvial sediments to the 

wetlands. The water would provide nutrients for wetland vegetation, thereby encouraging plant 

growth. This growth can stabilize wetland sediments, which makes them less susceptible to erosion. 

The water also prevents the sediments from drying out and compacting due to loss of pore water 

and oxidation of organic material (Yuill et al., 2009). Sediment deposition in wetlands is vital for the 

area to stave off sea-level rise. Without new sediments coming into the marsh, a major contributor 

to vertical building processes is removed, and the wetlands become more at risk to being inundated 

by rising sea levels (Yuill et al., 2009). The hydromodification of the Mississippi River has 

exacerbated these issues by preventing the flooding of coastal wetlands in Louisiana, and as a 

result, those areas are experiencing some of the highest land-loss rates in the world; therefore, the 

impact has been major. While the cumulative impacts to coastal habitats from the factors described 

above range from negligible to major, the incremental impact to those habitats from a proposed 

lease sale would be moderate. The relatively small contribution of a proposed lease sale to OCS 

oil- and gas-related activity would have impacts that are much less than those attributed to several 

sources, as noted above.

Coastal Restoration Programs

There are numerous coastal restoration programs that have been initiated since 1990 to 

address the long-term impacts to the Gulf of Mexico coastal ecosystem. These programs include 

State, Federal, and private funding and have resulted in substantial beneficial impacts to coastal 

habitats. The Coastal Wetlands Planning, Protection and Restoration Act, the Energy Policy Act of 

2005, the Oil Pollution Act of 1990, and the Resources and Ecosystems Sustainability, Tourist 

Opportunities, and Revived Economies of the Gulf Coast States Act are among the Federal laws 
Description of the Affected Environment and Impact Analysis 4-93

providing billions of dollars in funding for coastal restoration in the Gulf Coast States. Louisiana’s 

Coastal Protection and Restoration Authority has produced a Coastal Master Plan for implementing 

related restoration projects. The various programs involved are discussed in detail in Chapter 

3.3.2.8.3. 

4.3.1.2.4 Incomplete or Unavailable Information

BOEM has identified incomplete or unavailable information regarding estuarine habitat. 

There is incomplete information about routine impacts, as the scenario forecast is only an estimate, 

and many global factors can affect OCS oil- and gas-related activity. There also remains 

unavailable information about the future rates of oil spills, as well as spill locations and volumes of 

oil.

There are unknowns regarding the future restoration efforts that are being planned, such as 

what projects would ultimately be constructed and how successful they may be. In addition, the 

future rates of relative sea-level rise are not known with certainty, and thus, resulting impacts to 

wetlands are unknown. Future rates of coastal development are unknown, as is the extent of 

impacts to estuarine systems thereof.

BOEM acknowledges that there remains incomplete or unavailable information that may be 

relevant to reasonably foreseeable significant impacts on estuarine systems. This incomplete or 

unavailable information includes potential data on the Deepwater Horizon, explosion, oil spill, and 

response that may be forthcoming. As there is substantial information available since the 

Deepwater Horizon explosion, oil spill, and response, which is included in this Multisale EIS, BOEM 

believes that the incomplete or unavailable information regarding the effects of the Deepwater 

Horizon explosion, oil spill, and response on estuarine systems would likely not be essential to a 

reasoned choice among alternatives. Regardless of the costs involved, it is not within BOEM’s 

ability to obtain this information from the NRDA process within the timeline contemplated in the 

NEPA analysis for this Multisale EIS. BOEM’s subject-matter experts have used what scientifically 

credible information is available in their analyses, and applied it using accepted scientific 

methodology. BOEM has determined that the information is not essential to a reasoned choice 

among alternatives. Many studies have been produced that demonstrate the effects of exposure of 

wetland plants to crude oil, covering a wide range of exposure intensity, longevity, and oil 

characteristics. Much has been learned about the different survival and recovery rates of various 

plant species. In addition, studies have been produced regarding the long-term impacts of canal 

dredging and pipeline installation on wetlands. A proposed lease sale would result in a relatively 

minor addition to existing routine activities and accidental events, and therefore, the incremental 

contribution to wetland impacts from a proposed lease sale would be minor to moderate depending 

on the alternative and given what is currently known.

The potential for impacts from changes to the affected environment (post-Deepwater

Horizon) and cumulative impacts remains whether or not the No Action or an action alternative is 

chosen, and therefore, the incremental contribution from a proposed action would be minor relative 
4-94 Gulf of Mexico Multisale EIS

to cumulative impacts. BOEM used reasonably accepted scientific methodologies to extrapolate 

from existing information in completing this analysis and formulating the conclusions presented here.

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

BOEM reviewed and analyzed the impacts to coastal habitats from routine OCS oil- and gasrelated activities, reasonably foreseeable accidental events, and the incremental contribution of a 

proposed action to the cumulative impacts to wetlands. It is expected that impacts from pipeline

emplacement would be negligible with only 0-1 pipeline landfalls projected, and any impacts would 

be reduced or eliminated through mitigation (e.g., avoidance of impacts by use of modern 

techniques such as directional drilling). Although maintenance dredging of navigation channels and 

canals is expected to occur, a proposed action is expected to contribute only minimally to the need 

for this dredging. Secondary impacts to estuarine systems from a proposed action would result from 

OCS oil- and gas-related vessel traffic contributing to the erosion and widening of navigation 

channels and canals. Overall, the impacts to these habitats from routine activities associated with a 

proposed action are expected to be moderate due to the small length of projected onshore pipelines, 

the minimal contribution to the need for maintenance dredging, the mitigating measures that would 

be used to further reduce these impacts, and taking into account the estimated hundreds of acres of 

land loss attributed to vessel traffic related to a proposed action over 70 years.

The greater threat from an oil spill to coastal habitat is from a coastal spill as a result of a 

nearshore vessel accident or pipeline rupture. While a resulting slick may cause impacts to wetland

habitat and surrounding seagrass communities, the equipment, vessel traffic, and personnel used to 

clean it up can also generate impacts to the area. Close monitoring and restrictions on the use of 

bottom-disturbing equipment would be needed to avoid or minimize those impacts. In addition, an 

assessment of the area covered, oil type, and plant composition of the wetland oiled should be made 

prior to choosing remediation treatment. Offshore oil spills resulting from a proposed action would 

have a low probability of contacting and damaging large areas of the coast, except in the case of a 

catastrophic event, which is not reasonably foreseeable and not expected to occur as a result of a 

proposed lease sale (Catastrophic Spill Event Analysis white paper, USDOI, BOEM, 2017). This is 

because of the distance of the projected OCS oil- and gas-related activity to the coast, the likely 

weathered and therefore less toxic condition of oil (through evaporation, dilution, and 

biodegradation) should it reach the coast, and because wetlands are somewhat protected by barrier 

islands, peninsulas, sand spits, and currents. Overall, impacts to estuarine habitats from oil spills 

associated with activities related to a proposed action would be expected to be minor because of the 

distance of most of the resulting activities from the coast, expected weathering of spilled oil, 

projected low probability of large spills near the coast, resiliency of wetland vegetation, and available 

cleanup techniques.

Cumulative impacts to wetlands are caused by a variety of factors, including the OCS 

oil- and gas-related and non-OCS oil- and gas-related activities discussed above. Development 

pressures in the coastal regions of the GOM have been largely the result of tourism and residential 

beach side development, and this trend is expected to continue. The cumulative effects of human 
Description of the Affected Environment and Impact Analysis 4-95

and natural activities in the coastal area have severely degraded the deltaic processes and have 

shifted the coastal area from a condition of net land building to one of net land loss. Deltaic 

Louisiana is expected to continue to experience the greatest loss of wetland habitat in the GOM. 

Wetland loss is also expected to continue in coastal Texas, Mississippi, Alabama, and Florida, but at 

slower rates. As a result, numerous coastal restoration programs have been initiated since 1990 to 

address the long-term impacts to the Gulf of Mexico coastal ecosystem. These programs include 

State, Federal, and private funding and have resulted in substantial beneficial impacts to coastal 

habitats. A proposed action represents a small (>4.5%) portion of the cumulative OCS Program that 

would occur over the 50-year analysis period. Impacts associated with a proposed action are a 

minimal part of the overall OCS oil- and gas-related impacts. The incremental contribution of a 

proposed action to the cumulative impacts on coastal wetlands is expected to be moderate. 

4.3.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of this alternative would be similar to those of Alternative A, except that there 

would be negligible impacts to coastal wetlands and submerged vegetation in Texas because no 

new OCS oil- and gas-related activity is forecasted in the WPA along the Texas coast with this 

alternative. Under Alternative B, the resulting OCS oil- and gas-related activity would be located off 

the coasts of Louisiana, Mississippi, and western Florida. The greater distance between these 

activities and the coastal habitats of Texas would reduce the impacts along the Texas coast, 

whether from routine activities or accidental events. Less use of service bases in Texas is likely, 

and the distance between oil spills associated with this alternative and the Texas coast is expected 

to be greater. The incremental contribution of Alternative B to the cumulative impacts on coastal 

wetlands is expected to be moderate. 

4.3.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

The impacts of this alternative would be less than those of Alternative A, as only a fraction of 

the resulting activity forecast for Alternative A is projected under Alternative C. For this alternative, 

there would be negligible impacts to coastal wetlands and submerged vegetation in Louisiana; 

negligible impacts to Mississippi, Alabama, and the panhandle of western Florida; and 

incrementally more impacts to the wetlands and submerged vegetation of Texas, compared with 

Alternative A. However, Alternative C would have less potential for impact than Alternative A or B as 

the level of projected OCS oil- and gas-related activities and impact-producing factors are much less 

in the WPA. For example, a range of 22-96 production wells are projected to be drilled and 

developed under Alternative C, whereas 46-671 production wells are projected to occur under 

Alternative B. The significance of impact-producing factors on estuarine habitats would be less for 

Alternative C than for Alternative A, as discussed in Chapter 2.2.2. Therefore, the incremental 

contribution of Alternative C to the cumulative impacts on coastal wetlands is expected to be minor. 
4-96 Gulf of Mexico Multisale EIS

The coastal barrier beaches 

and associated dunes are 

those beaches and dunes that 

line the coast of the northern 

Gulf of Mexico, including both

barrier islands and beaches 

on the mainland.

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

Available Unleased Blocks Subject to the Topographic Features, Live Bottom

(Pinnacle Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

The impacts of this alternative would be nearly identical to those of Alternative A because the 

available unleased blocks with topographic features do not contain wetlands or submerged 

vegetation and are too distant (over 25 km; 16 mi) from the coast to have indirect impacts either. In 

addition, there are only 367 blocks subject to the Topographic Features Stipulation, 74 blocks 

subject to the Live Bottom (Pinnacle Trend) Stipulation, and 32 blocks subject to the Blocks South of 

Baldwin County, Alabama, Stipulation. This relatively small percentage of the total number of 

unleased blocks would not be expected to generate a great contribution to OCS oil- and gas-related 

activity if leased.

4.3.1.2.9 Alternative E—No Action

If a proposed action does not occur, there would be no additional impacts to estuarine 

habitats; however, cumulative impacts from all sources, including OCS and non-OCS sources, would 

be the same as Alternative A. There could be some incremental increase in impacts caused by a 

compensatory increase in imported oil and gas to offset reduced OCS production, but it would likely 

be negligible. 

4.3.2 Coastal Barrier Beaches and Associated Dunes

In this chapter, BOEM reviewed and analyzed OCS oiland gas-related routine activities and reasonably foreseeable 

accidental events. The approach of the analysis is to focus on 

the potential impact-producing factors from OCS oil- and gasrelated routine activities (i.e., exploration, development, and 

production), as well as accidental events and cumulative 

impacts (Table 4-10). Routine activities associated with a 

proposed action that takes place on the OCS, where wells are 

drilled and platforms and pipelines are installed, would not 

impact the coastal barrier beaches, which are located from 3 to greater than 200 nmi (3.5 to 

230.2 mi; 5.6 to 370.4 km) away. Other routine activities that support offshore oil and gas 

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

installation, trash and debris, and construction of support infrastructure in the coastal areas, could 

potentially impact beaches and dunes. An analysis of the potential impacts from accidental events, 

primarily oil spills, associated with a proposed action is presented in this chapter, as is the 

incremental contribution of a proposed action to the cumulative impacts to beaches and dunes. 

Cumulative Impacts were analyzed for OCS oil- and gas-related activities and for other sources that 

could affect coastal barrier beaches and dunes (i.e., human impacts, storms, vessel traffic, 

subsidence, and sea-level rise).
Description of the Affected Environment and Impact Analysis 4-97

Table 4-10. Coastal Barrier Beaches and Associated Dunes Impact-Producing Factors That Are 

Reasonably Foreseeable.

Coastal Barrier 

Beaches and 

Associated Dunes

Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Pipeline

Construction and 

Maintenance

Negligible Negligible Negligible Negligible None

Navigation 

Channel 

Maintenance 

Dredging

Minor Minor Minor Minor None

Vessel Operation 

(Support Use of 

Navigation 

Channels)

Negligible Negligible Negligible Negligible None

Disposal of OCSRelated Wastes Negligible Negligible Negligible Negligible None

Construction and 

Use of Coastal 

Support 

Infrastructure

Negligible Negligible Negligible Negligible None

Accidental Impacts

Oil Spills Minor Minor Minor Minor None

Cumulative Impacts

Incremental 

Contribution2 Minor Minor Minor Minor None

OCS Oil and Gas3 Major

Non-OCS Oil and 

Gas4 Major

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

Impact-Level Definitions

For this analysis, the following definitions were used to categorize impacts to coastal 

beaches and dunes: 
4-98 Gulf of Mexico Multisale EIS

• Negligible – Little to no measurable impacts in species composition and 

abundance and/or altering of beach profile or ecological function.

• Minor – Measureable but short-term and localized impacts to species 

composition and abundance and/or altering of beach profile or ecological 

function.

• Moderate – Damage to coastal habitats (impacts to species composition and 

abundance and/or altering of beach profile or ecological function) that is 

detectable, spatially extensive, but temporary and not severe. Can also be used 

to describe localized land loss.

• Major – Severe, bringing about detectable changes in species composition and 

abundance and/or altering of beach profile or ecological function well beyond that 

of normal variability. Changes would likely need to be both long-lasting and 

spatially extensive to have such an effect.

4.3.2.1 Description of the Affected Environment

Barrier beaches and associated dune habitats from Texas to the Florida panhandle may be 

impacted by activities resulting from a proposed action. These areas are comprised of the following 

geologic subareas:

• the barrier island complex of southern Texas;

• the Chenier Plain of eastern Texas and western Louisiana;

• the Mississippi River Delta complex of southeastern Louisiana;

• the barrier-island and Pleistocene Plain complex of Mississippi and Alabama; 

and

• the Florida panhandle.

Barrier islands make up more than two-thirds of the northern GOM shore (Morton et al., 

2004). These shorelines are usually sandy beaches that can be divided into several interrelated 

environments. Generally, beaches consist of a shoreface, foreshore, and backshore. The 

shoreface slopes downward and seaward from the low-tidal water line, under the water. The 

nonvegetated foreshore slopes up from the water to the beach berm-crest. The backshore is found 

between the beach berm-crest and the dunes, and may be sparsely vegetated. The dune zone of a 

barrier landform can consist of a single low dune ridge, several parallel dune ridges, or a number of 

curving dune lines that may be stabilized by vegetation. These elongated, narrow landforms are 

composed of wind-blown sand and other unconsolidated, predominantly coarse sediments.

Tropical storms and hurricanes are normal occurrences in the GOM and along the coast. 

The GOM has been hit extremely hard by very powerful hurricanes. These storms caused damage 

to barrier islands and beaches in all five of the Gulf Coast States. Beaches can recover naturally 
Description of the Affected Environment and Impact Analysis 4-99

from the damage done by storms, but it may take many years (Houser et al., 2015). During storms, 

large waves can overwash lower coastal barriers, creating overwash fans or terraces behind and 

between the dunes. With time, opportunistic plants would reestablish on these flat, sand terraces, 

followed by the usual vegetative succession for this area. Along more stable barriers, where 

overwash is rare, the vegetative succession in areas behind the dunes is generally complete. 

Vegetation in these areas consists of scrubby woody vegetation, marshes, and forested wetlands. 

Saline and freshwater ponds may be found among the dunes and on the landward flats. These flats 

may grade into wetlands and intertidal mud flats that fringe the shore of lagoons, islands, and 

embayments. In areas where no bay or lagoon separates barrier landforms from the mainland, the 

barrier vegetation grades into scrub or forest habitat of the mainland.

Once formed, barrier islands are not static landforms; they are dynamic, with winds and 

waves constantly reworking and moving the barrier island sand, wherefore barrier landform 

configurations continually change, accreting and eroding, in response to these environmental 

conditions. Landform changes can be seasonal and cyclical, such as seen with the onshore 

movement of sand during the summer and offshore movement during the winter. Noncyclical 

changes in landforms can be progressive, causing barrier island movement. Barrier islands are also 

periodically reworked due to hurricanes and tropical storms.

Transgressive and regressive landforms are common across the GOM. A transgressive 

sequence moves the shore landward. Transgressive coastal landforms around the GOM have low 

profiles and are characterized by narrow widths; low, sparsely vegetated, and discontinuous dunes; 

and numerous, closely spaced, active washover channels. A regressive sequence moves the shore 

seaward. Regressive barriers have high and broad dune profiles. These thick accumulations of 

sand may form parallel ridges.

Barrier islands, particularly vegetated ones with freshwater and or saltwater pools, may serve 

as habitat for a wide variety of animal life, especially birds (Chapter 4.8), including threatened and 

endangered species. The islands and spits protect the bays, lagoons, estuaries, salt marshes, 

seagrass beds, and other wetland environments, some of which may contain threatened or 

endangered species (Chapter 4.9). Barrier islands in the northern GOM extending from Atchafalaya 

Bay, Louisiana, to Mobile Bay, Alabama, are disintegrating rapidly as a result of combined physical 

processes involving sediment availability, sediment transport, and sea-level rise.

Oil from the Deepwater Horizon explosion and oil spill was documented by shoreline 

assessment teams to have stranded on approximately 600 mi (965 km) of beach shoreline 

(Deepwater Horizon Natural Resource Damage Assessment Trustees, 2016). Cleanup activities 

were conducted on 410 mi (660 km) of the affected beach. Two years after the spill, some oil 

remained on 427 mi (687 km) but at much lesser amounts (Michel et al., 2013a; OSAT-2, 2011). 

Beach shorelines were affected by oiling and response actions, with the most severe cleanup 

actions killing all creatures that burrow in beach sand (Deepwater Horizon Natural Resource 

Damage Assessment Trustees, 2016). As beaches experienced erosion and deposition, oil would 

become buried, exposed, and remobilized multiple times, resulting in chronic re-oiling. Tropical 
4-100 Gulf of Mexico Multisale EIS

Storm Lee (2011) and Hurricane Isaac (2012) caused extensive beach erosion and remobilization of 

oil residues. Oil residue mats were observed between the toe of the beach and the first offshore 

sand bar, providing another source of chronic sources of surface residue balls and surface residue 

patties (Michel et al., 2013a). Over time, more of the remaining oil has continued to be removed, 

while toxicity has decreased as the oil is further weathered. The buried supratidal samples 

underwent less biodegradation due to lack of oxygen, but they were estimated in 2011 to decrease 

to 20 percent of current levels within the next 5 years (OSAT-2, 2011).

As a result of the Deepwater Horizon explosion and oil spill, protective berms were 

constructed in Louisiana seaward of barrier islands to protect the inland marshes, wetlands, and 

seagrasses from incoming oil associated with this large spill. The berms were ineffective in stopping 

the oil, and none of the estimates of how much oil was collected on the berms was much more than 

1,000 bbl (National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, 2011). 

It took approximately 5 months to build roughly 12.5 mi (20.1 km) of berms at a cost of 

approximately $220 million. Long-term effects can include changes in hydrology and sediment 

transport along the coastal barrier islands, the loss of sand resources, and adverse impacts to 

benthic and pelagic organisms (Martinez et al., 2012). As a result, such berms are not likely to be 

approved as a response measure in the future.

Texas Barrier Island Complex

The barrier islands in Texas extend from the Mexican border to Galveston Bay. The GOM 

coastline of Texas is about 367 mi (590 km) long. The average rate of erosion of the Texas 

shoreline, from 1950 through 2012, was 2.3 ft (0.7 m) per year. While some of the coast has been 

gaining land, rates vary by location, with numerous locations experiencing rates of more than 11.5 ft 

(3.5 m) per year (State of Texas, General Land Office, 2015).

The barrier islands are mostly accreted sediments that were reworked from river deposits, 

previously accreted Gulf shores, bay and lagoon sediments, and exposed seafloors (White et al., 

1986). The Texas coast has both low- and high-profile barriers. South Padre Island is an example 

of a low-profile barrier, with its narrow shape and discontinuous frontal dunes that are inundated by 

storm surges. Matagorda Island is an example of a high-profile barrier, which is typically wide with 

continuous, well-vegetated dune ridges (Morton et al., 2004).

Padre Island National Seashore encompasses 70 mi (112 km) of coastline, making it the 

longest stretch of undeveloped barrier island in the world. It borders the Laguna Madre, a 

hypersaline lagoon, and it provides habitat for numerous plants and animals. It also serves as an 

important nesting ground for the endangered Kemp’s ridley sea turtles. 

Chenier Plain

The Chenier Plain of eastern Texas and western Louisiana began developing about 

2,800 years ago. During that period, Mississippi River Delta sediments were intermittently eroded, 

reworked, and carried into the Chenier Plain area by storms and coastal currents. This deposition 
Description of the Affected Environment and Impact Analysis 4-101

gathered huge volumes of mud and sand, forming a shoreface that slopes very gently, almost 

imperceptibly, downward for a very long distance offshore. This shallow mud bottom is viscous and 

elastic, which generates hydrodynamic friction (Bea et al., 1983). Hence, wave energies along the 

barrier shorelines of the Chenier Plain are greatly reduced, causing minimal longshore sediment 

transport along the Chenier Plain (USDOI, GS, 1988). More recently, this shoreline has been 

eroding as sea level rises, converting most of this coast to transgressive shorelines.

The barrier beaches of the Chenier Plain are generally narrow, low, and sediment starved 

due to the nature of coastal currents and the shoreface. In some places, beach erosion has 

exposed relic marsh platforms that were buried by past overwash events, resulting in beaches 

composed of shelly sand, or discontinuous mud deposits among muddy sands.

Mississippi River Delta Complex

The Mississippi River Delta region comprises much of coastal Louisiana and adjacent 

Mississippi. It stretches from the Atchafalaya Bay to the Chandeleur Islands of Louisiana. Most 

barrier shorelines of the Mississippi River Delta are transgressive and trace the seaward remains of 

a series of five abandoned deltas. As a lobe of the Delta is abandoned by a shift in drainage, that 

portion begins to subside slowly into the sea and is further reduced by erosion. Some of the 

sediment may be reworked by wind and waves into barrier islands. The Chandeleur Islands and 

Grand Isle are examples of this. Gradually, woodland vegetation became established on the dune

sands (e.g., oaks and oleander). Salty meadows, marshes, and lagoons occupy the lower terrain. 

The shorefaces of the Mississippi River Delta complex slope gently seaward, which reduces wave 

energies at the shorelines. Mud flats are exposed during very low tidal events. This slope is not as 

shallow as that found off the Chenier Plain.

The barrier islands associated with the Mississippi River Delta are at the greatest risk for 

degradation from hurricanes and sand budget deficits; these include the Chandeleur-Breton Island, 

Timbalier Island, and Isle Dernieres chains in Louisiana. These chains of individual transgressive 

barrier island segments have progressively diminished in size while migrating landward (McBride 

et al., 1992). Most of southeastern Louisiana’s barrier beaches are composed of medium to coarse 

sand. Most dune zones of the Mississippi River Delta contain low, single-line dune ridges that may 

be sparsely to heavily vegetated.

Mississippi and Alabama Coasts

The Dog Keys define the Mississippi Sound of Mississippi and Alabama. The MississippiAlabama barrier islands have experienced increased rates of land loss since the mid-1800’s 

because of storms and sand budget deficits. The centers of most of the islands are migrating 

westward (Richmond, 1962; Otvos, 1979). These islands generally have high beach ridges and 

prominent sand dunes. They are well vegetated among and behind the dunes and around ponds.

Mississippi has about 33.9 mi (54.6 km) of barrier beaches (USDOI, FWS, 1999). The 

western district of the Gulf Islands National Seashore is located in Mississippi. Some of the habitats 
4-102 Gulf of Mexico Multisale EIS

representative of coastal barrier and seagrass ecosystems are found on or behind Horn and Petit 

Bois Islands, which were designated as Wilderness Areas by Congress in 1978 through the 

establishment of the Gulf Islands Wilderness Area.

Dauphin Island, Alabama, represents about another 7 mi (11 km) of barrier beaches. The 

beaches are separated by wide passes with deep channels. Shoals (a place where a sea, river, or 

other body of water is shallow) are typically adjacent to these barriers. Unlike the other barrier 

islands, Dauphin Island is essentially a low-profile, transgressive barrier island, except for its eastern 

end. The western end is characterized by small dunes and many washover fans, exposed marsh 

deposits, and tree stumps exposed in the surf zone. The Gulf Shores region of Alabama extends 

from Mobile Point eastward to the Florida boundary, a distance of about 31 mi (50 km) (Smith, 

1984).

Florida Panhandle

The Florida panhandle has extensive beaches with multiple habitats, including sandy 

mainland beaches, broad peninsulas, and narrow barrier islands. Two long, narrow barrier islands 

(Santa Rosa Island and Perdido Key) form the Gulf shore west of Destin and are part of the Gulf 

Islands National Seashore (Figure 4-26 in Chapter 4.12.1). Both can be reached by road and 

experience tourism in the form of camping, picnicking, swimming, bird watching, and fishing.

Coastal land loss from shoreline change in the Florida panhandle is associated with erosion 

of sandy beaches and barrier islands, especially around inlets, while bays and lagoons tend to 

experience lower loss rates because the waterbodies are generally small or protected by erosion 

control structures (Morton et al., 2004). The average long-term erosion rate, from the 1800’s 

through 2001, was estimated as -2.6 ft/yr (-0.8 m/yr), which is lower than the other Gulf Coast 

States. This can be attributed to relatively low wave energy and frequent beach nourishment 

(Morton et al., 2004).

These barrier beaches and dune habitats also play an important role to ESA-listed species; 

BOEM consults on these species with FWS. These species include sea turtles, beach mice, and 

birds; to read about the protected species that use these habitats, refer to Chapters 4.9.2, 4.9.3, 

and 4.9.4, respectively.

4.3.2.2 Environmental Consequences

4.3.2.2.1 Routine Activities

This chapter considers impacts from routine activities associated with a proposed action to 

the physical shape and structure of barrier beaches and associated dunes. The primary impactproducing factors from routine activities associated with a proposed action that could affect these 

environments include pipeline emplacements, vessel traffic (navigation channel use) and dredging, 

trash and debris, and infrastructure construction.
Description of the Affected Environment and Impact Analysis 4-103

Pipeline Emplacements

Many existing OCS Program-related pipelines made landfall on barrier islands and 

shorelines (Chapter 3.1.3.3.1). Pipeline landfall sites on barrier islands could potentially cause 

accelerated beach erosion and island breaching. This occurs when pipeline canals are dug through 

beaches, and then widen over time. A proposed action is not expected to include new pipelines that 

make landfall on barrier islands or mainland beaches (0-1 new pipeline landfalls are projected). 

Modern pipeline construction typically employs horizontal, directional (trenchless) drilling techniques 

and open-water routes to the extent possible to avoid damages to estuarine systems and beaches. 

Similar features are now commonly required to minimize any impacts from pipeline landfalls. 

Studies have shown that little to no impact to barrier beaches results from techniques like directional 

pipeline emplacement (LeBlanc, 1985; Wicker et al., 1989). Federal and State regulatory programs 

and permitting processes encourage the use of directional boring technology to reduce and perhaps 

eliminate impacts to barrier beaches or dunes. Because of the regulations and new construction 

methods, and the limited projection for, at most, one new pipeline landfall, the effects on barrier 

beaches and dunes from pipeline laying activities associated with a proposed lease sale are 

expected to be negligible.

Vessel Traffic and Dredging

Vessel traffic that may support a proposed action and navigation channels projected to be 

used in support of a proposed action are discussed in Chapters 3.1.3.3.4 and 3.1.4.3 and are 

shown in Table 3-7. As a result of a proposed action, it is not expected that the number of OCS oiland gas-related navigation channels would change. Waves generated by boats, ships, barges, and 

other vessels erode unprotected shorelines and accelerate erosion in coastal barrier beaches

already affected by natural erosion processes. Only a limited reach of the navigation channels cross 

the shoreline adjacent to beaches or dunes, and these reaches are generally armored with rock. 

The existing armored navigation channels minimize or eliminate the potential for shoreline erosion 

from vessel traffic.

A proposed action is estimated to account for <2 percent of the service-vessel traffic in 

navigation canals associated with the OCS Program from 2017 through 2066 (Chapters 3.1.3.3.4

and 3.1.4.3; Tables 3-2 and 3-7). Erosion of coastal barrier beaches and associated dunes from 

vessel traffic resulting from a proposed action are expected to be negligible because of the small 

percentage of total vessel traffic related to the OCS Program and the armoring of the channels most 

highly used for OCS oil- and gas-related activities.

Periodic maintenance dredging is expected in existing navigation channels through barrier 

passes and associated bar channels. Maintenance dredging of barrier inlets and bar channels 

removes sediment from the system, contributing to beach erosion. Materials from maintenance 

dredging of bar and pass channels are typically discharged to nearby ocean dumping sites in the 

GOM (Chapter 3.3.2.8.5) or they are used for marsh creation or beach nourishment projects as part 

of mitigation (Morton, 2008). Jetties or bar channels serve as sediment sinks by intercepting 

sediment in longshore littoral drift (the movement of sediment along the shoreline by currents). 
4-104 Gulf of Mexico Multisale EIS

Negative effects of sediment sinks created by jetties can be mitigated by filling the downdrift side of 

the jetty with appropriate sediment. These dredging activities are permitted, regulated, and 

coordinated by the COE with the appropriate State and Federal resource agencies. Effects from 

maintenance dredging related to a proposed action on coastal barrier beaches and associated 

dunes are expected to be minor due to the small contribution from a proposed action to total 

channel use and the offsetting effects of beach nourishment.

Coastal Infrastructure Construction 

Projected new facilities that are attributed to the OCS Program and a proposed action would 

rarely, if ever, be located on coastal barrier beaches (Chapter 3.1.7). There are 0-1 gas processing 

plants projected to be constructed as a result of a proposed action. Existing inland facilities may, 

through natural erosion and shoreline recession, be located in the barrier beach and dune zone and 

contribute to erosion there. A proposed action may extend the life and presence of facilities in 

eroding areas, which could accelerate localized erosion; however, the impacts on coastal barrier 

beaches and associated dunes in the vicinity of the construction of a gas processing plant from a 

proposed action are expected to be negligible or none, as the location of such a facility is not likely 

to be adjacent to beaches.

4.3.2.2.2 Accidental Events

The types and sources of spills that may be reasonably foreseeable from a proposed lease 

sale and their characteristics are described in Chapter 3.2. There is also a risk analysis of oil spills

in Chapter 3.2.1. A low-probability catastrophic spill is discussed in the Catastrophic Spill Event 

Analysis white paper (USDOI, BOEM, 2017).

The only accidental event associated with a proposed action likely to impact beaches would 

be a spill and the associated cleanup activities. Impacts to biological, recreational, and 

archaeological resources associated with beach and dune environments are described in the impact 

analysis chapters for those specific resources (Chapters 4.9, Protected Species; 4.12, Recreational 

Resources; and 4.13, Archaeological Resources).

Effects of Oil on Beaches

The effects from coastal oil spills depend on the geographic location, volume, and rate of the 

spill, type of oil, oil-slick characteristics, oceanic conditions, season at the time of the spill, and 

response and cleanup efforts (Chapter 3.2.8). The resiliency of coastal beaches and the impact of 

oil on these beaches are, in part, based on the toxicity of the oil’s components once it reaches the 

beaches. Microbial biodegradation can reduce the toxicity of crude oil by decreasing PAH 

concentrations. However, submerged oil mats found in GOM waters adjacent to beaches can resist 

weathering and may serve as long-term sources of remnant oil and PAHs to beach ecosystems 

(Hayworth et al., 2011; Elango et al., 2014). In addition, buried supratidal samples undergo less 

biodegradation due to a lack of oxygen (OSAT-2, 2011).
Description of the Affected Environment and Impact Analysis 4-105

If unweathered oil reached the beaches, the associated interstitial microfauna would be 

affected in several ways, including community shifts, toxic effects, and the physical disturbance of 

response efforts. A shift in the microbial community would tend to increase dominance by 

hydrocarbon degraders (Kostka et al., 2011). This shift can occur within days of contamination with 

crude oil, stimulating the breakdown of the contaminants present in the oil (Horel et al., 2012). Toxic 

constituents of the oil can have both lethal and sublethal impacts to resident plants and fauna. 

Equipment and personnel used in cleanup efforts can generate the greatest direct impacts to an 

area, such as the removal of sand from the beaches, disturbance of beach and foredune sands 

through foot traffic, mechanized cleanup equipment (e.g., sifters), dispersal of oil deeper into sands 

and sediments, and foot traffic in marshes impacting the distribution of oils and marsh vegetation.

Coastal Spills 

Coastal spills from damage to pipelines, vessel collisions, and malfunctions of onshore 

production or storage facilities have the greatest potential for affecting the coastal barrier beaches

due to their proximity to the resources. Because very little OCS oil- and gas-related activity takes 

place on beaches, inland spills that occur in the vicinity of GOM tidal inlets present a greater 

potential risk to barrier beaches and dunes because the inlets can provide a path for oil to reach the 

beaches.

The number and most likely spill sizes to occur in coastal waters in the future are expected to 

resemble the patterns that have occurred in the past as long as the level of energy-related, other 

commercial, and recreational activities remains the same. BOEM’s analysis shows that 96 percent 

of spills from OCS oil-and gas-related activity are <1 bbl, with an average size of <0.05 bbl 

(Anderson et al., 2012). Table 3-13 shows that there was only one spill ≥1,000 bbl in the coastal 

waters from Texas through Alabama during the period 2002-2015. Because of the small contribution 

to all such spills from a proposed action, the small size of most spills, the percentage of spilled oil 

volume that would likely reach coastal barrier beaches, and the breakdown of contaminants by 

microbial communities, impacts of coastal spills to barrier beaches and dunes are expected to be 

minor. 

Offshore Spills 

There are various factors and conditions that affect the toxicity and severity of the impacts of 

oil spills on the barrier island systems, dunes, and the associated vegetation. For an offshore spill 

<1,000 bbl to make landfall, the spill would have to occur proximate to State waters (defined as 

3-12 mi [5 19 km] from shore). If a spill were to occur proximate to State waters, only a spill >50 bbl 

would be expected to have a chance of persisting long enough to reach land. Spills ≥50 and 

<1,000 bbl are infrequent (Chapter 3.2.1.5.4). If an oil spill contacted the shoreline, the intertidal 

area and the beach face would likely be contacted. For the oil to contact the dunes, extreme high 

tides would be needed to carry oil from a spill across and onto the dunes.

Two important variables during an oil spill for impacts on beaches and dunes involve location 

(distance of spill from landfall) and weather. For example, if there is sufficient distance and 
4-106 Gulf of Mexico Multisale EIS

favorable weather conditions between the spill and landfall, the oil can be dispersed, thinned, and 

emulsified. This would allow for conditions supportive of biodegradation, volatilization, and 

photooxidation to break down the oil. Most spills from the OCS are likely to be distant enough that, 

should a slick from such a spill make landfall, the volume of oil remaining in the slick is expected to 

be small. Due to the distance of the spill from shore, the weather, the time oil remains offshore, and 

dispersant use (Chapter 3.2.8.2.2), OCS crude oil would be less toxic when it reaches the coastal 

environments. For example, after the Deepwater Horizon explosion and oil spill, the majority of oil 

deposits on GOM beaches were highly weathered and samples showed 86-98 percent depletion of 

total polycyclic aromatic hydrocarbons (PAHs) (OSAT-2, 2011). However, should spills from the 

OCS occur proximate to State waters, they could reach shore before much weathering, evaporation, 

or dispersal had occurred.

The probabilities of an offshore spill ≥1,000 bbl occurring and contacting environmental 

features are described in Chapter 3.2.1.4.8. The probabilities of oil spills ≥1,000 bbl occurring and 

contacting State waters can be found in Figure E-20. The highest probability as a result of a 

proposed action is estimated at 26 percent for the State waters of both Texas and West Louisiana. 

Should spills from the OCS occur proximate to State waters, they could reach shore before much 

weathering, evaporation, or dispersal had occurred. However, because the majority of spills 

estimated to occur are relatively small (>99% estimated to be <50 bbl), the distance from coastal 

communities, improved technologies, and the dynamic nature of the coastal environment, offshore 

spills are expected to have a minor impact on the estuarine community.

Trash and Debris

Trash and debris (Chapter 3.2.7) can be an issue for coastal habitats, including beaches 

and dunes and the fauna that reside in these habitats. Fauna that utilize barrier beaches and dunes 

could ingest or become entangled in trash and debris. This can have lethal impacts like suffocation 

or sublethal impacts like loss of a limb. The BSEE provides information on marine debris and 

awareness and requires training of all OCS personnel through NTL 2015-BSEE-G03, which also 

informs operators of regulations set forth by other regulatory agencies (i.e., the USEPA, USCG, and 

others). Due to the annual awareness training required by marine debris mitigations, the handling of 

waste and trash by industry has improved greatly and the effects on coastal habitats are minimized. 

Because lease stipulations and regulations, as clarified by NTLs, are in place to reduce impacts from 

marine trash and debris, impacts related to marine trash and debris would result in negligible

impacts to coastal barrier beaches and associated dunes.

4.3.2.2.3 Cumulative Impacts

This cumulative analysis considers the effects of impact-producing factors related to a 

proposed action, prior and future OCS lease sales in the Gulf of Mexico, State oil and gas activities, 

other governmental and private projects and activities, and pertinent natural processes that may 

affect barrier beaches and dunes. 
Description of the Affected Environment and Impact Analysis 4-107

OCS Oil- and Gas-Related Impacts

Pipeline Emplacements, Vessel Traffic (Navigation Channel Use), Dredging, Trash and 

Debris, and Infrastructure Construction

Continued navigation channel use and dredging support of a proposed action could impact 

coastal habitats. Maintenance dredging of barrier inlets and bar channels is expected to continue, 

which removes sediment from the system, contributing to beach erosion. Mitigation of impacts 

involves strategically placing dredged sediment where adjacent barrier-island shores would receive it 

for island nourishment and rebuilding (Morton, 2008). Beneficial uses of dredged material include 

beach nourishment for the more sandy materials, and much of the impacts from dredging are 

expected to be mitigated through the beneficial use program implemented by the COE. Further 

discussion of the beneficial use of dredged material can be found in Chapter 3.3.2.3.5. Impacts to 

beaches from maintenance dredging would occur regardless if a proposed action is implemented or 

not. Between 6 and 19 percent of traffic using navigation channels in the GOM is expected to be 

related to the cumulative OCS Program (Tables 3-23 and 3-7). A proposed action is estimated to 

account for less than 2 percent of the service-vessel traffic in the OCS. Impacts to beaches from 

maintenance dredging related to a proposed action are expected to be minor. Impacts to beaches 

from OCS oil- and gas-related marine debris would be negligible. 

The effects to coastal barrier beaches and associated dunes from pipeline emplacements 

and the construction or continued use of infrastructure in support of a proposed action are expected 

to be restricted to temporary and localized disturbances. Existing pipelines were placed using older 

techniques and have caused and would continue to cause barrier beaches to narrow and breach. 

Pipeline landfalls projected in support of the cumulative OCS scenario are expected to cause 

negligible impacts to barrier beaches because of the use of modern, nonintrusive installation 

methods.

Oil Spills

Due to the proximity of coastal spills to barrier islands and beaches, such spills pose a threat 

to coastal barrier beaches and dunes. As noted in Table 3-13, a few coastal spills ≥1,000 bbl have 

been recorded in the coastal waters from Texas through Alabama during the period 2002-2015. 

Spills that occur in or near the Chandeleur or Mississippi Sounds could affect the coastal barrier 

beaches and dunes in the Gulf Islands National Seashore and the Breton National Wildlife Refuge.

Oil from most offshore spills, except perhaps from OCS oil- and gas-related activities close to 

the boundary with State waters, is expected to be weathered and normally treated offshore. 

Therefore, most of the toxic components would have dissipated by the time it contacts coastal 

beaches. The cleanup impacts of these spills could result in a short-term (up to 2 years) adjustment 

in beach profiles and configurations as a result of sand removal and disturbance during the cleanup 

operations. Cleanup efforts would be monitored in an effort to ensure the least amount of 

disturbance to the areas. Oil from the Deepwater Horizon explosion and oil spill was documented by 

shoreline assessment teams to have stranded on approximately 600 mi (965 km) of beach shoreline 
4-108 Gulf of Mexico Multisale EIS

(Deepwater Horizon Natural Resource Damage Assessment Trustees, 2016). Cleanup activities 

were conducted on 410 mi (660 km) of the affected beach. Two years after the spill, some oil 

remained on 427 mi (687 km) but at much lesser amounts (Michel et al., 2013a; OSAT-2, 2011). 

Beach shorelines were affected by oiling and response actions, with the most severe cleanup 

actions killing all creatures that burrow in beach sand (Deepwater Horizon Natural Resource 

Damage Assessment Trustees, 2016). As beaches experience erosion and deposition, oil would 

become buried, exposed, and remobilized multiple times, resulting in chronic re-oiling. Tropical 

Storm Lee (2011) and Hurricane Isaac (2012) caused extensive beach erosion and remobilization of 

oil residues. Oil residue mats were observed between the toe of the beach and the first offshore 

sand bar, providing another source of chronic sources of surface residue balls and surface residue 

patties (Michel et al., 2013a). Over time, more of the remaining oil has continued to be removed, 

while toxicity has decreased as the oil is further weathered. The buried supratidal samples 

underwent less biodegradation due to lack of oxygen, but they were estimated to decrease to 

20 percent of current levels within 5 years (OSAT-2, 2011). Accidental spills as a result of a lowprobability catastrophic event are discussed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2017).

Spill data from the OCS shows that, over decades of activity, tens of thousands of barrels of 

oil have been spilled (Chapter 3.2.1.1.3), not including oil from the Deepwater Horizon oil spill. 

Cumulative OCS oil- and-gas-related spills resulting from all past and present leasing activities, 

including the millions of barrels that entered the Gulf of Mexico from the Deepwater Horizon oil spill,

are estimated to have had a major impact on coastal barrier beaches and dunes. However, the 

incremental increase in impacts from reasonably foreseeable oil spills related to a proposed action is 

expected to be minor. 

Non-OCS Oil- and Gas-Related Impacts

Vessel Traffic (Navigation Channel Use)

Construction of the existing navigation channels has replaced beaches with the waterways in 

some cases, while other channels were constructed using existing passes (Chapter 3.3.2.8.5). 

Construction of the channels involves removal of sand that is no longer available for longshore drift 

to adjacent beaches. Maintenance dredging of barrier inlets and bar channels would continue to 

remove sediment from the system, contributing to beach erosion. Sand is removed during dredging, 

and only a fraction of this sand is used for beach nourishment. Disposal of dredged material outside 

of the littoral zone represents a net loss of sand to the system, and thus, maintenance dredging has 

contributed to net deficits (Byrnes et al., 2012). These impacts would occur from necessary channel 

maintenance to accommodate all vessel traffic, resulting in moderate impacts to beaches. 

Oil Spills

Non-OCS oil- and gas-related oil spills can occur as a result of import tankers, barge, or 

shuttle tanker accidents during transit or offloading, State-related oil production activities, and 

various kinds of petroleum product transfer accidents. State-related oil production activities are 
Description of the Affected Environment and Impact Analysis 4-109

concentrated in coastal areas, where spills could potentially cause greater impacts to beaches. The 

impacts of non-OCS oil- and gas-related spills are expected to be minor to moderate. 

The GOM has more natural oil seeps (providing ~980,000 bbl/year; refer to Chapter 

3.3.2.9.2) than any other marine environment in North America; therefore, it has a resident 

population of microbiota, including oil-biodegrading bacteria, that degrades additional oil that enters 

the environment (Atlas and Hazen, 2011). This resident microbial population increases the 

resiliency of beaches to oil spill impacts.

River Hydromodification and Beach Protection

Over the course of geological history, the barrier islands have migrated toward the present 

coast. The Gulf-facing coasts of the barrier islands have been eroded by the steady relative rise in 

sea level. Human disturbance has hastened the erosion of barrier beaches and dunes. Channel 

deepening and widening along the Mississippi River and other major coastal rivers, in combination 

with channel training and bank stabilization work, has resulted in the reduced delivery of sediment to 

the eroding deltas along the mouths of the rivers and to the offshore barrier islands. This, coupled 

with beach building and stabilization projects utilizing mined sands, jetties, groins, and other means 

of sediment capture, is depriving natural restoration of the barrier beaches through sediment 

nourishment and sediment transport.

Subsidence, erosion, and dredging of inland coastal areas with the concurrent expansion of 

tidal influences continually increase tidal prisms around the GOM. These changes may result in the 

opening and deepening of many new tidal channels that connect to the GOM and inland 

waterbodies. Due to the increased flow, these incremental changes would cause adverse impacts to 

barrier beaches and dunes. Efforts to stabilize the GOM shoreline have adversely impacted barrier 

landscapes. Large numbers and varieties of stabilization techniques for navigation channels have 

been applied along the Gulf Coast. These efforts have contributed to coastal erosion by depriving 

downdrift beaches of sediments, which accelerates erosion there, and by increasing or redirecting 

the erosional energy of waves (Morton, 1982). Over the last 20 years, dune and beach stabilization 

have been better accomplished by using more natural applications such as sand dunes, beach 

nourishment, and vegetative plantings. Impacts of river channelization and beach protection are 

expected to be moderate because of the disruption of sediment nourishment and sediment 

transport.

Other Anthropogenic and Natural Processes

Barrier beaches along the Gulf Coastal have experienced erosion and landward retreat 

(marine transgression) because of natural processes enhanced by human activities (Chapters 

3.3.2.8 and 3.3.2.9). Adverse effects on barrier beaches and dunes have resulted from changes to 

the natural dynamics of water and sediment flow along the coast. This can happen in an attempt to 

control catastrophic floods and change the natural environment to better accommodate navigation 

on waterways used to support OCS oil- and gas-related and non-OCS oil- and gas-related vessel 

traffic. Rising sea levels are expected to continue to inundate or fragment low-lying coastal areas, 
4-110 Gulf of Mexico Multisale EIS

including sandy beaches and barrier islands (Dahl, 2011). Sea-level rise and coastal subsidence 

and tropical storms exacerbate and accelerate the erosion of coastal barrier beaches along the Gulf 

Coast. The Gulf Coast and the associated barrier islands and dunes have been impacted by highintensity hurricanes and tropical storms over the past millenia, resulting in natural changes in barrier 

island topography and decreases in beach elevation (USDOI, GS, 2008; Barras, 2007). Due to the 

more gentle slopes, removal of beach ridges, and cuts into the mainland barrier beaches, the 

remnant transition zone between the water and the current beach ridge may be more vulnerable to 

spills. Historically, recovery of beaches to their pre-storm state ranges from years to decades 

(Houser et al., 2015).

If the topography is modified, it may result in hydrological changes that enable further 

sediment transport from the islands. This provides pathways for further erosion and saltwater 

intrusion into the less salt-tolerant interior vegetated habitats of the islands. The loss of elevation, 

combined with the shoreline retreat and removal of vegetation further aggravated by the hurricanes, 

allows for the expansion of the overwash zone. This lessens the pre-storm protection of the coast 

provided by these barrier islands. The reduction in island elevation results in less frontline protection 

to valuable marshes and puts urban and industrial areas protected by these marshes at a higher risk 

(USDOC, NMFS, 2007b).

Hurricanes and tropical storms would remain a part of the Gulf Coast weather pattern and 

would continue to affect the elevations of barrier islands, mainland beaches, and dunes. Depending 

on storm frequency and intensity, it may be possible for coastal restoration and protection projects to 

mitigate some of the physical damage to these areas.

Gulf Coast barrier beaches tend to occur at low elevations, between sea level and several 

feet above sea level. Beach erosion due to sea-level rise has increased along certain shorelines 

(Dahl, 2011). If current projections are realized and the sea level increases by 3.5 ft (1.1 m) in 

Galveston, Texas, by 2100 (USEPA, 2013a), much of Texas’ coastal beaches would be under water 

well before 2100. A more conservative estimate of sea-level rise, known as the AR4 scenario, calls 

for an increase (globally) of 16 in (41 cm) by 2100 (NRC, 2010). Even this rate of increase would be 

likely to impact Gulf Coast beaches, especially when local, relative sea-level rise is considered. 

Since 1870, global sea level has risen by about 8 in (20 cm) (USEPA, 2013a). Even at current 

measured rates of relative sea-level rise, large areas of GOM coastal beaches can be expected to 

be inundated (refer to Chapter 3.3.2.8.1). Impacts to coastal habitats are expected to be major due 

to the large scale of inundation from sea-level rise and the erosion due to hurricanes and human 

activities.

Recreational Use, Tourism, and Development

Recreational use of beaches is discussed in Chapter 4.12 (Recreational Resources). 

Recreational use of barrier beaches and dunes can have impacts on the stability of the landform. 

Vehicle and pedestrian traffic on sand dunes can stress and reduce the density of vegetation that 

binds the sediment and stabilizes the dune. Destabilized dunes are more easily eroded by winds, 
Description of the Affected Environment and Impact Analysis 4-111

waves, and traffic. Recreational vehicles and even hikers have caused impacts where road access 

is available and the beach is wide enough to support vehicle use. Most barrier beaches in Texas are 

accessible to people for encouraged recreational use because of public road access. It also 

provides for public acquisition of private beachfront property. Most barrier beaches in Louisiana are 

relatively inaccessible for regular recreational use because they are in coastal areas with limited 

road access. Mississippi has coastal beaches behind the barrier islands that are accessible for 

recreational use, and the barrier islands experience extensive recreational use by boaters. Most 

barrier beaches in Alabama and the panhandle of Florida are accessible to foot traffic through road 

access, and their use is encouraged. There would continue to be seaside real-estate development 

where road access is available. The protection of dunes, beaches, and coastal environments are 

regulated through the Coastal Management Programs of the states, as well as the COE’s permitting 

program. This helps to assure that projects are constructed consistent with the Federal CZMA 

guidelines in order to preserve the integrity of the coastal ecosystem. In the years 2004 through 

2009, there were modest gains in marine and estuarine nonvegetated wetlands, a category that 

includes beaches (Dahl, 2011; Dahl and Stedman, 2013). A proposed action would not provide any 

additional access that would result in increased negative cumulative impact to the barrier beaches 

and dunes.

Development along the Gulf Coast has impacted coastal barrier beaches. Census data 

show that coastal areas are experiencing much higher growth than noncoastal areas. However, 

census data may underestimate this trend due to undercounting of seasonal residents. 

Infrastructure needed to support seasonal influxes of people can impact coastal barrier beaches 

(Dahl and Stedman, 2013). Hotels, restaurants, stores, and bars have been built on or adjacent to 

many coastal beaches, resulting in loss of habitat as well as the introduction of wastewater into 

coastal waters. High-use “amenity” beaches can benefit from frequent beach nourishment projects 

that supply large quantities of sand. Impacts are to some extent offset by coastal restoration 

programs. Examples of these programs are the Coastal Impact Assistance Program (CIAP), the 

Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA), and the RESTORE Act 

(refer to Chapter 3.3.2.8.3). Due to the protection from development of beaches included in the Gulf 

Islands National Seashore, restrictions on development by the various regulatory programs and 

continuing cumulative impacts of past development on coastal barrier beaches, impacts are 

expected to be moderate. 

Coastal barrier beaches have experienced severe adverse cumulative impacts from human 

activities and natural processes. Human activities that have caused the greatest adverse impacts 

are navigation channel stabilization and maintenance, beach stabilization structures, oil spills, 

recreation and development, river channelization and damming, and pipeline canals. Most barrier 

beaches in Texas, Alabama, and Florida are accessible to people for recreational use, and their use 

is encouraged and intense. Excessive recreational use can result in damage to dunes, resulting 

from the loss of dune stabilizing plants. Existing pipelines were placed using older techniques and 

have caused and may continue to cause barrier beaches to narrow and breach. Natural and 

anthropogenic events have combined to cause erosion of barrier and shoreline landforms along the 
4-112 Gulf of Mexico Multisale EIS

Gulf Coast. Cumulative impacts to barrier beaches and dunes from these sources are considered to 

be major. 

While the cumulative impacts to coastal barrier beaches from the factors described above 

range from negligible to major, the incremental impact to beaches from a proposed lease sale 

would be minor. The relatively small contribution of a proposed lease sale to OCS oil- and 

gas-related activity would have impacts that are much less than those attributed to several sources, 

as noted above.

4.3.2.2.4 Incomplete or Unavailable Information

BOEM acknowledges that there remains incomplete or unavailable information regarding 

coastal barrier beaches and associated dunes in the GOM. There is incomplete information about 

routine impacts, as the scenario forecast is only an estimate, and many global factors can affect 

OCS oil- and gas-related activity. There also remains unavailable information about future rates of 

oil spills, as well as the locations and volumes of oil. Future rates of coastal development are 

unknown, as is the extent of such impacts to coastal barrier beaches. There are also unknowns 

regarding the future restoration efforts being planned, such as what specific projects would ultimately 

be constructed and how successful they may be. In addition, the future rates of relative sea-level 

rise are not known with certainty (Hausfather, 2013), and thus, the resulting impacts to coastal 

barrier beaches and associated dunes are unknown.

A large body of information regarding impacts of the Deepwater Horizon explosion, oil spill, 

and response upon coastal barrier beaches and associated dunes has been developed and 

continues to be developed through the NRDA process, but information remains incomplete. As 

there is substantial information available since the Deepwater Horizon explosion, oil spill, and 

response, which has been analyzed for this Multisale EIS, BOEM believes that the incomplete or 

unavailable information regarding the effects of the Deepwater Horizon explosion, oil spill, and 

response on coastal barrier beaches and dunes would likely not be essential to a reasoned choice 

among alternatives. The incomplete information would not be available within the timeframe 

contemplated by the NEPA analysis of this Multisale EIS. However, much is known about the extent 

of the oiling of beaches and the continuing degradation of the remaining oil.

BOEM has determined that the information is not essential to a reasoned choice among 

alternatives. BOEM’s subject-matter experts have used what scientifically credible information is 

available in their analyses, applied using accepted scientific methodology. Many studies have been 

produced that demonstrate the effects of exposure of beaches to crude oil, covering a wide range of 

exposure intensity, longevity, and oil characteristics. Much has been learned about the effect of 

oil-spill cleanup on beaches and the degradation rates of oil over time. In addition, studies have 

been produced regarding the long-term impacts of navigation canal dredging on beaches and barrier 

islands. A proposed lease sale would result in a relatively minor addition to existing routine activities 

and accidental events, and therefore, the incremental increase in impacts to coastal barrier beaches

and dunes from a proposed lease sale would be minor given what is currently known. The potential 
Description of the Affected Environment and Impact Analysis 4-113

for impacts from changes to the affected environment (post-Deepwater Horizon) and cumulative 

impacts remains whether or not the No Action or an action alternative is chosen.

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

Impacts from most routine activities related to a proposed action would be expected to be 

minor since most routine activities are located far from coastal beaches. Impacts to coastal barrier 

beaches and associated dunes from pipeline emplacements, and construction or continued use of 

infrastructure in support of a proposed action are expected to be restricted to temporary and 

localized disturbances and to cause negligible impacts to barrier beaches because of the small 

number of expected pipeline landfalls and the fact that any new OCS oil- and gas-related 

infrastructure would not be expected to be constructed on barrier beaches. The contribution from a 

proposed action to channel use and maintenance is expected to result in minor impacts. Indirect 

impacts from routine activities, such as disruption of sediment transport by maintenance dredging of 

channels or erosion resulting from pipeline emplacements, are minor. 

Minor and localized impacts to the physical shape and structure of barrier beaches and 

associated dunes may be expected to occur as a result of accidental events, such as oil spills, 

associated with a proposed action. Such impacts could be a result of cleanup efforts in addition to 

the spill itself. Should a spill contact a barrier beach, sand removal during cleanup activities would 

likely be minimized because current spill-response activities discourage physical cleanup methods 

that impact beach profiles. The Net Environmental Benefits Analysis done as part of the OSAT-2 

report (2011) noted that the environmental impacts of residual oil remaining after cleanup are 

relatively small when compared with the impacts of continued cleanup efforts on both beach habitats 

and associated resources.

The impacts of oil spills and related cleanup efforts from both OCS oil- and gas-related and 

non-OCS oil- and gas-related sources to the Gulf Coast depend on the size, frequency, distribution, 

locations, and collective spatial and temporal features of the spills. Impacts would include stranding 

of surface residue balls and patties, and submerged tar mats may persist in adjacent waters, 

representing a chronic source of contamination, observed particularly after storms. Changes to 

beach topography could result from cleanup efforts. Overall impacts from oil spills are expected to 

be minor, with the exception of a catastrophic event, which is not considered reasonably 

foreseeable and is not part of a proposed action or likely expected to occur. Impacts as a result of a 

low-probability catastrophic event are discussed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2017).

Compared with other impact-producing factors on coastal barrier beaches and dunes, the 

incremental contribution of Atlernative A to the cumulative impacts to these resources is expected to 

be minor. 
4-114 Gulf of Mexico Multisale EIS

4.3.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of this alternative would be similar to those of Alternative A, except that there 

would be negligible impacts to coastal barrier beaches and dunes in Texas because no OCS 

oil- and gas-related activity is forecast in the WPA along the Texas coast with this alternative. Under 

Alternative B, the resulting OCS oil- and gas-related activity would be located off the coasts of 

Louisiana, Mississippi, and western Florida. The greater distance between these activities and the 

coastal habitats of Texas would reduce impacts along the Texas coast whether from routine 

activities or accidental events. Less use of service bases in Texas is likely, and the distance 

between oil spills associated with this alternative and the Texas coast is expected to be greater. 

Compared with other impact-producing factors on coastal barrier beaches and dunes, the 

incremental contribution of Atlernative B to the cumulative impacts to these resources is expected to 

be minor. 

4.3.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

The impacts of this alternative would be less than those under Alternative A, as only a 

fraction of the resulting activity forecasted for Alternative A is projected for Alternative C. For this 

alternative, there would be negligible incremental impacts to coastal barrier beaches and dunes in 

Louisiana; and zero to negligible impacts to Mississippi, Alabama, and the panhandle of western 

Florida; and incrementally more impacts to the beaches and dunes of Texas. However, Alternative 

C would have less potential for impact than Alternative A or B as the level of projected OCS oil- and 

gas-related activities and impact-producing factors are much less in the WPA. For example, a range 

of 11-67 production wells are projected to be drilled and developed under Alternative C, whereas 

58-464 production wells are projected to occur under Alternative B. The significance of impactproducing factors on coastal barrier beaches and dunes would be somewhat less for Alternative C 

than for Alternative A, as discussed in Chapter 2.2.2. Compared with other impact-producing 

factors on coastal barrier beaches and dunes, the incremental contribution of Atlernative C to the 

cumulative impacts to these resources is expected to be negligible to minor. 

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

Available Unleased Blocks Subject to the Topographic Features, Live Bottom

(Pinnacle Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

The impacts of this alternative would be nearly identical to those of the alternative it is 

combined with because the available unleased blocks with topographic features do not contain 

coastal barrier beaches and dunes and are too distant (over 25 km; 16 mi) from the coast to have 

indirect impacts. In addition, there are only 367 blocks subject to the Topographic Features 

Stipulation, 74 blocks subject to the Live Bottom (Pinnacle Trend) Stipulation, and 32 blocks subject 

to the Blocks South of Baldwin County, Alabama, Stipulation. This relatively small percentage of the 

total number of available unleased blocks would not be expected to generate a great contribution to 

OCS oil- and gas-related activity, if leased.
Description of the Affected Environment and Impact Analysis 4-115

4.3.2.2.9 Alternative E—No Action

If a proposed lease sale does not occur, there would be no additional impacts to barrier 

beaches and associated dunes; however, cumulative impacts would be the same as for 

Alternative A. There could be some incremental increase in impacts caused by a compensatory 

increase in imported oil and gas to offset reduced OCS production, but it would likely be negligible. 

4.4 DEEPWATER BENTHIC COMMUNITIES

This chapter presents an analysis of the potential impacts on deepwater benthic 

communities as a result of routine activities and accidental events associated with a GOM proposed 

action and a proposed action’s incremental contribution to cumulative impacts. The analysis is not 

exhaustive of all possible impacts of routine activities and accidental events; rather, it focuses on 

those most relevant for decisionmakers. Potential impacts from a catastrophic oil spill, including 

long-term impacts and recovery, are detailed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2017). “Deep water” is a term of convenience used in this analysis to refer to water 

depths >300 m (984 ft). BOEM defines “deepwater benthic communities” as including both

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

deepwater coral communities (deepwater coral plus coral-associated fauna).

Chemosynthetic communities are based on the presence of various organisms that do not 

depend on photosynthetic processes for metabolism. In the GOM, they are formed around natural 

hydrocarbon seepages where chemosynthetic bacteria consume methanes and sulfides and 

chemosynthetically derive amino acids and sugars for respiration, and then excrete carbon dioxide 

that may result in calcium carbonate precipitation. Eventually, sufficient precipitates can form hard 

carbonate substrates on which higher order megafauna such as structure-forming deepwater

sponges and corals can settle. Relatively large numbers of invertebrate and fish species (refer also 

to Chapter 4.7) may be attracted to structurally complex microhabitats, which can provide shelter, 

feeding areas, and nursery grounds (Fraser and Sedberry, 2008). Over 330 chemosynthetic 

communities have been confirmed in the GOM to date (for spatial distribution, refer to Figure 4-11 in 

Chapter 4.4.1.1 below). More communities likely exist, but much of the seafloor has not yet been 

visually surveyed to allow direct observation. Much is still unknown about chemosynthetic

communities, despite increasing research in recent decades.

Deepwater coral communities are known to occur throughout the GOM (Figure 4-10) and 

new communities are routinely discovered with almost every new deepwater research cruise 

(USDOC, NOAA, 2014a). As with shallow-water live bottom communities (Chapter 4.6), most GOM 

deepwater corals require exposed hard substrate for attachment and growth. They often co-occur 

on authigenic substrates (substrates that have been generated where they are found) created by 

chemosynthetic processes; however, they also routinely colonize other natural or artificial hard 

substrates not associated with hydrocarbon seepage. In addition to hard and soft deepwater corals, 

these communities include other associated sessile and motile benthic megafauna such as sponges, 

anemones, echinoderms, crustaceans, and fishes.
4-116 Gulf of Mexico Multisale EIS

Figure 4-10. Deepwater Coral Records from NOAA’s National Deep-Sea Coral and Sponge 

Database (USDOC, NOAA, 2014a).

Impact Analysis Process and Scope

The impact significance criteria and resulting conclusions presented in Table 4-11 focus on 

the overall functioning, resilience, and ecosystem level importance of deepwater benthic 

communities throughout U.S. waters of the GOM. The potential magnitude of impact for each of 

these impact-producing factors that are reasonably foreseeable is provided in Table 4-11 to help the 

reader quickly identify the level of potential impacts for each impact-producing factor, shown in the 

table both with and without the anticipated BOEM mitigations to make clear the considerable 

difference that results from these mitigations. The impact-level definitions and the analyses 

supporting these conclusions are then discussed in detail in this chapter. Postlease, site-specific 

analyses would focus more on potential localized impacts of individual development activities (e.g., 

proposed drilling of a well) to individuals, discrete communities, and small patches of benthic habitat. 

Those analyses would also detail site-specific protective mitigations required prior to approval of 

such activities.

Table 4-11. Deepwater Benthic Communities Impact-Producing Factors That are Reasonably 

Foreseeable.

Deepwater Benthic 

Communities Magnitude of Potential Impact1 

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Bottom-Disturbing Activities and Drilling-related Sediment and Waste Discharges

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation

Minor to Minor to Minor to Minor to

None

Major Moderate Moderate Major
Description of the Affected Environment and Impact Analysis 4-117

Accidental Impacts

Bottom-Disturbing Activities and Drilling-Related Sediment and Operational Waste Discharges

With Mitigation Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Without Mitigation

Minor to Minor to Minor to Minor to

None

Major Moderate Moderate Major

Oil Spills

With Mitigation Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Without Mitigation

Minor to Minor to Minor to Minor to

Major Moderate Moderate Major None

Cumulative Impacts

Incremental 

Contribution2 Negligible Negligible Negligible Negligible None

OCS Oil and Gas3 Negligible to

Minor

Non-OCS Oil and 

Gas4

Negligible to

Major

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the 

same geographic range and within the same timeframes as a proposed action, but they are not 

related to the OCS Oil and Gas Program.

Impact-Level Definitions

For this analysis, the following definitions were used to categorize impacts to deepwater

benthic communities:

• Negligible – Impacts to deepwater benthic communities are largely 

undetectable. There is some potential for even undetectable impacts to cause 

slight changes to a local community’s species abundance and composition, 

community structure, and/or ecological functioning, but any such changes would 

be spatially localized, short term in duration, and would not alter the overall 

status of GOM deepwater benthic communities.

• Minor – Impacts to deepwater benthic communities are detectable but cannot be 

clearly distinguished from natural variation. Such impacts could result in 

changes to a local community’s species abundance and composition, community 

structure, and/or ecological functioning, but would be spatially localized, short 
4-118 Gulf of Mexico Multisale EIS

term in duration, and would not alter the overall status of GOM deepwater 

benthic communities.

• Moderate – Impacts to deepwater benthic communities detectably cause 

substantial, population-level changes in species composition, community 

structure, and/or ecological functioning. These impacts would be expected to be 

spatially extensive but are expected to only temporarily alter the overall status of 

GOM deepwater benthic communities; long-term recovery to pre-impact levels is 

likely.

• Major – Impacts to deepwater benthic communities detectably cause substantial, 

population-level changes in species composition, community structure, and/or 

ecological functioning. These impacts would be expected to be spatially 

extensive and noticeably alter the overall status of GOM deepwater benthic 

communities such that long-term recovery to pre-impact levels is unlikely.

Because of the similarity and overlap of the effects of many activities that occur in the OCS, 

the primary, reasonably foreseeable routine and accidental impact-producing factors for deepwater

benthic habitats can be grouped into three main categories:

(1) bottom-disturbing activities (Chapter 3.1.3.3.2; routine and accidental);

(2) drilling-related sediment and waste discharges (Chapter 3.1.5.1; routine and 

accidental); and 

(3) oil spills (Chapter 3.2.1; accidental).

Cumulative Impacts were also considered, in two steps: impacts resulting from OCS oil- and 

gas-related activities (same as routine activities and accidental events); and impacts resulting from 

non-OCS oil- and gas-related sources, namely fishing and climate change.

Some impact-producing factors relevant to deepwater benthic communities are already 

analyzed in greater detail in other sections and need only be briefly summarized here. Chapter 4.7

(Fishes and Invertebrate Resources) details the potential impacts to marine invertebrates from 

anthropogenic sound and concludes the impact would be negligible. Note that despite the growing 

body of information available for fishes, there is comparatively little information available on sound 

detection and sound-mediated behaviors for marine invertebrates. Chapter 4.7 (Fish and 

Invertebrate Resources) also details the impacts of routine activities and the cumulative impacts

from the presence and subsequent removal of OCS oil- and gas-related infrastructure. These 

impacts include the post-installation physical presence of OCS oil- and gas-related infrastructure, 

effects of decommissioning activities such as explosive and nonexplosive removals, and conversion 

of platforms to artificial reefs. While the total contribution of OCS infrastructure is still only a small 

percentage of natural hard bottoms (Gallaway et al., 2009), and is projected to further decrease 

throughout the period covered by this analysis (Chapter 3.3.1.5), the presence, removal, and/or 

conversion of artificial hard substrates colonized by sessile invertebrates are likely to result in 
Description of the Affected Environment and Impact Analysis 4-119

localized community changes, such as changes in species diversity in the area (Schroeder and 

Love, 2004). While individual presence, removal, or conversion actions at specific locations do not 

cause more than negligible impacts when considered against the broader scope of this analysis, 

when the sum of such actions are considered cumulatively for all planning areas and over 50 years, 

such impacts could be greater for individual species . This is because select sessile benthic species 

commonly associated with OCS oil and gas structures could be noticeably influenced over time by 

the overall presence (or removal) of OCS oil- and gas-related infrastructure. For example, a 

particular deepwater coral species’ Gulfwide spatial distribution may shift over time because of the 

presence or removal of structures in otherwise soft bottom-dominated areas. Such a change (were 

it to occur) could be considered a moderate level impact for that species If it represented a 

detectable change in the species’ spatial distribution, such a range shift might have potential 

long-term effects related to dispersal and genetic connectivity to other populations of that species. 

Such potential impacts are not necessarily either positive or negative; that would be dependent on 

the species and a number of complex ecological factors. Some evidence of these types of changes 

(in particular, range expansion) has been documented for some shallow-water hermatypic species 

(Sammarco et al., 2012), but similar research specific to deepwater coral is lacking, as noted in the 

“Incomplete or Unavailable Information” section below. More peer-reviewed literature about this 

topic is available for fish resources, as detailed in Chapter 4.7. 

Several additional impact-producing factors described in Chapter 3.1 were evaluated for 

potential impacts on deepwater benthic communities. These impact-producing factors were not 

carried forward for full analysis because any potential effects were judged to be either not 

reasonably foreseeable or having such a miniscule impact that they would not rise to the level of 

negligible impact. These impact-producing factors include surface oil-spill response efforts (refer to 

Chapter 4.6.1, Topographic Features), impacts from geological and geophysical activities other than 

bottom disturbance (bottom disturbance is covered below), and potential impacts from a sinking 

vessel. A sinking vessel settling on a deepwater benthic community is not a reasonably foreseeable 

impact-producing factor. Even if such an incident did occur, it would not have a population-level 

impact despite likely crushing or smothering deepwater benthic organisms in the local area of direct 

contact.

Some potential impact-producing factors are already regulated by other Federal agencies 

and/or international treaties. For example, the discharge of marine debris is subject to a number of 

laws and treaties (refer to Chapter 3.2.7). These include the Marine Debris Research, Prevention, 

and Reduction Act; the Marine Plastic Pollution Research and Control Act; and the MARPOLAnnex V Treaty. Regulation and enforcement of these laws is conducted by a number of agencies 

such as the U.S. Environmental Protection Agency, NOAA, and the U.S. Coast Guard. To further 

reduce potential impacts, the BSEE provides information on marine debris and requires training of all 

OCS personnel through the “Marine Trash and Debris Awareness and Elimination” NTL (NTL 2015-

BSEE-G03). This NTL instructs OCS operators to post informational placards that outline the legal 

consequences and potential ecological harm of discharging marine debris. This NTL also states that 

OCS workers should complete annual marine debris prevention training; operators are also 

instructed to develop a certification process for the completion of this training by their workers. 
4-120 Gulf of Mexico Multisale EIS

Historically, compliance with this NTL has been mandatory as a result of the Protected Species 

Stipulation that has been applied at the lease sale stage. These various laws, regulations, and NTL 

would likely minimize any potential damage to live bottom resources from the discharge of marine 

debris related to OCS oil- and gas-related operations. Nonetheless, some accidental release of 

marine debris is still likely to occur as a result of OCS oil- and gas-related operations and could 

theoretically have limited effects on deepwater benthic organisms (e.g., physical damage caused by 

strong currents pushing debris into fragile organisms or ingestion of plastics by invertebrates). 

However, the amount of debris in question would not suffice to cause even negligible impacts when 

considered at the scale of the overall population of deepwater benthic communities in the GOM. 

One possible exception would be frequent accidental losses of very large items such as pipeline

segments with the potential to crush or smother organisms. That impact-producing factor is briefly 

discussed under “Accidental Events: Bottom-Disturbing Activities” below, even though any such 

losses are expected to be very rare. In all cases, the likelihood of spatial overlap with debris from 

OCS oil- and gas-related vessels or infrastructure is inherently small due to the relatively rare and 

patchy distribution of live bottom communities in the GOM, particularly in areas of the western and 

northern GOM, which have the greatest amount of OCS oil- and gas-related operations.

Another potential impact-producing factor that is largely governed by (and potential impacts 

reduced by) external regulations is the potential presence of toxins in drilling muds and cuttings 

and/or produced waters (Chapter 3.2.6). Because of the regulations issued by the USEPA and/or 

international treaties designed to keep toxins below harmful levels, hazardous levels of toxins are 

generally not expected to reach deepwater benthic communities. Nonetheless, potential impacts 

from toxins are briefly discussed under “Routine Activities” below.

Historical Protections of Deepwater Benthic Communities

Protective measures have been developed over time based on the nature and sensitivity of 

various benthic habitats and their associated communities, as understood from decades of BOEMfunded and other environmental studies. NTL 2009-G40, “Deepwater Benthic Communities,” 

provides operators with relevant information and consolidates guidance for the avoidance and 

protection of the various types of potentially suitable habitat for chemosynthetic organisms and 

deepwater coral. As detailed in NTL 2009-G40, all plans submitted for permitted deepwater (300 m 

[984 ft] or greater) activities are reviewed for the presence of deepwater benthic communities that 

may be impacted by the proposed activity. Lessees must provide site-specific survey and narrative 

information regarding sensitive benthic features with each exploration plan (EP), development 

operations coordination document (DOCD), and development and production plan. These plans are 

reviewed by subject-matter experts on a case-by-case basis to determine whether a proposed 

operation could impact a benthic community. If an impact from drilling or other seafloor disturbance 

(e.g., anchors, anchor chains, rig emplacement, pipeline emplacement) is judged likely based on 

site-specific information derived from the geohazard survey data, BOEM’s databases and studies, 

other published research, or another creditable source, the operator would be required to relocate 

the proposed operation (i.e., distancing) or undertake other appropriate mitigations to prevent such 

an impact. As detailed above, BOEM’s subject-matter experts make use of the best available 
Description of the Affected Environment and Impact Analysis 4-121

datasets to identify probable habitat that could support deepwater chemosynthetic and coral 

communities, including BOEM’s publicly available database of water-bottom anomalies (USDOI, 

BOEM, 2015b). This analysis assumes continuation of the protective measures outlined in NTL 

2009-G40.

4.4.1 Description of the Affected Environment

Gulf of Mexico Continental Slope and Deepwater Biological Resources

The northern GOM’s continental slope region has been described as the most complex in the 

world (Carney, 1997 and 1999; Rowe and Kennicutt, 2009). It is a transitional environment 

influenced by processes of both the shelf (<650 ft; 200 m) and the abyssal GOM (>3,199 ft; 975 m). 

This transitional character applies to both the pelagic and the benthic realms. Regional topography 

of the slope consists of basins, knolls, ridges, and mounds derived from the dynamic adjustments of 

salt to the introduction of large volumes of sediment over long time scales.

Deepwater environments of the GOM have only been well studied in recent decades. 

Historically, there have been relatively few studies due to the logistical difficulties involved in 

deepwater research. The first substantial collections of deep GOM benthos were made during the 

cruises of the USCG and Geodetic Steamer, Blake, between 1877 and 1880. Rowe and Menzel 

(1971) reported the first quantitative data published about GOM infauna for this region. Texas A&M 

University researchers performed the first major study of the deep northern GOM between 1964 and 

1973 (Pequegnat, 1983). A more recent study was completed by LGL Ecological Research 

Associates and Texas A&M University in 1988 (Gallaway et al., 1988). The major Northern Gulf of 

Mexico Continental Slope Habitats and Benthic Ecology Study (Rowe and Kennicutt, 2009) lasted 

6 years. The recent studies provide extensive background information on deepwater GOM habitats 

and biological communities relevant to this analysis and can be referenced for more detail.

The proposed lease sale area encompasses a vast range of habitats and water depths. The 

shallowest portions start nearshore at the boundary of State waters, and the deepest portions extend 

to approximately 11,483 ft (3,500 m) south of the Sigsbee Escarpment (which is centrally located in 

the Gulf of Mexico), nearly into the deepest part of the GOM (14,383 ft; 4,384 m). De Soto and 

Mississippi Canyons are perhaps the two most notable geologic seafloor features in the northern 

GOM, exerting control over water currents, upwelling features, and biological productivity. The 

sediment-laden freshwater plume from the Mississippi River and the Gulf Loop Current are the major 

controlling oceanographic factors in the GOM.

As noted in the introduction, “deep water” is a term of convenience used in this analysis to 

refer to water depths >300 m (984 ft). The majority of deepwater seafloor in the GOM is typically 

covered by clay and silt (Jenkins, 2011). In, on, and directly above these sediments live a wide 

variety of “benthos,” or benthic organisms, from microbiota up through megafauna. Their ecological 

adaptations are extremely varied and can include absorption of dissolved organic material, 

symbiosis, collection of food through filtering, mucous webs, seizing, or other mechanisms, including 

chemosynthesis.
4-122 Gulf of Mexico Multisale EIS

Deepwater fauna can be grouped into major assemblages defined by depth: (1) upper 

slope; (2) mid-slope; (3) lower slope; and (4) abyssal plain (Rowe and Kennicutt, 2009). The 450-m 

(1,476-ft) depth contour delimits the approximate beginning of the aphotic zone where visible light no 

longer penetrates and where photosynthesis cannot occur, with resultant changes to processes of 

food consumption, biological decomposition, and nutrient regeneration. The continental shelf-slope 

transition zone begins at approximately 150 m (492 ft) and the abyssal zone begins at approximately 

≥1,000 m (3,281 ft). The different zones can be subdivided into the following divisions and 

characteristic faunal assemblages:

• Shelf-Slope Transition Zone (150-450 m; 492-1,476 ft)—A very productive part of 

the benthic environment. Demersal fish are dominant, many reaching their 

maximum populations in this zone. Asteroids, gastropods, and polychaetes are 

common.

• Archibenthal Zone – Horizon A (475-740 m; 1,558-2,428 ft)—Although less 

abundant, demersal fish are a major constituent of the fauna, as are gastropods 

and polychaetes. Sea cucumbers are more numerous.

• Archibenthal Zone – Horizon B (775-950 m; 2,543-3,117 ft)—This zone 

represents a major change in the number of species of demersal fish, asteroids, 

and echinoids, which reach maximum populations here. Gastropods and 

polychaetes are still numerous.

• Upper Abyssal Zone (1,000-2,000 m; 3,281-6,562 ft)—Number of fish species 

decline while the number of certain invertebrate species appear to increase. Sea 

cucumbers and galatheid crabs are common

• Mesoabyssal Zone (2,300-3,000 m; 7,546-9,843 ft)—Fish species are few, and 

echinoderms continue to dominate the megafauna.

• Lower Abyssal Zone (3,200-3,800 m; 10,499 to 12,468 ft)—A large asteroid is 

the most common megafaunal species.

• The lowermost layer is the benthic zone, defined as the seafloor itself and the 

waters immediately above it. This zone is a repository of sediments where 

nutrient storage and regeneration take place in association with the solid and 

semisolid substrate (Pequegnat, 1983). Characteristic fauna may be different 

depending on the actual depth of the seafloor.

The vast majority of the GOM seabed is comprised of soft sediments (Rezak et al., 1983; 

Jenkins, 2011). Sediments in the EPA consist primarily of sand, while a more heterogeneous mix of 

sand, silt and clay sediments are found in the CPA and WPA (Brooks and Darnell, 1991). Grain size 

is the most important substrate characteristic affecting the distribution of benthic fauna (Vittor, 2000). 

Major groups of animals that live in sediments include (1) megafauna (visible to the naked eye), 

(2) macrofauna (>0.01 in; 0.3 mm), (3) meiofauna (0.002-0.01 in; 0.063-0.3 mm), and (4) bacteria 

and other microbiota. All of these groups are represented throughout the entire GOM − from the 
Description of the Affected Environment and Impact Analysis 4-123

continental shelf to the deepest abyssal depths. This analysis focuses on the better known 

megafauna and their habitats.

4.4.1.1 Chemosynthetic Communities

Chemosynthetic communities begin with chemosynthetic bacterial mats that consume 

methane and sulfides; their respiration results in the precipitation of calcium carbonate, forming a 

new, hard substrate. Certain deepwater coral and sponge species can then attach to exposed hard 

substrates, thereby adding to the structural complexity of the microhabitat. The new benthic habitats 

provided by chemosynthetic fauna themselves (i.e., tubeworm bushes), the precipitated hard 

substrates, and the framework-forming corals can all be used by a variety of benthic invertebrates, 

including echinoderms (e.g., brittle stars and basket stars), sea anemones, crustaceans, and other 

benthic megafauna such as fishes, forming a broader chemosynthetic community.

The GOM has some of the most active natural oil and gas seeps in the world (refer to 

Chapter 3.3.2.9.2; NRC, 2003), and these seeps can support development of complex deepwater

faunal communities (MacDonald et al., 1993; Cordes et al., 2010). The food chain for this 

ecosystem relies on bacterial primary producers that consume methanes and sulfides rather than 

performing photosynthesis. Chemosynthetic bacteria, which live on mats, in sediment, and in 

symbiosis with chemosynthetic invertebrates, use a carbon source independent of photosynthesis to 

make sugars and amino acids. Chemosynthetic invertebrates including tube worms and bivalves 

occur at or near hydrocarbon seeps and are dependent upon these symbiotic chemosynthetic 

bacteria as their primary food source (MacDonald, 1992). The bacteria live within specialized cells 

in the invertebrate organisms and are supplied with oxygen and chemosynthetic compounds by the 

host via specialized blood chemistry (Fisher, 1990). The host, in turn, lives off the organic products 

subsequently released by the chemosynthetic bacteria and may even feed on the bacteria 

themselves.

Distribution and Detection

Chemosynthetic communities typically occur in the GOM at water depths greater than 300 m 

(984 ft). Temperatures at these depths range from about 55°F to 39°F (13°C to 4°C). Water 

currents at the seafloor are typically about 2-4 inches/second (5-10 centimeters/second). The 

chemosynthetic communities occur as widely scattered, patchy habitat, developing where 

hydrocarbons seep up with a moderate flow.

Seeps occur where hydrocarbons vertically migrate up through faults, fractures along the 

flanks of salt, or other conduits to the seafloor. The exact number of natural oil prone seeps in the 

GOM is not known, although volume estimates have been made using surface oil slicks and the 

numbers are considerable (MacDonald et al., 1993; NRC, 2003). Even less is known about the 

number and flux of gas prone seeps in the GOM since no observable sea-surface slicks are present. 

What is known is that the overwhelming majority of seeps are gas prone, not oil prone. Hydrocarbon 

source rocks occur over broad areas several kilometers beneath the seafloor of the GOM, but 

chemosynthetic communities occur in isolated areas at the seafloor. Seepage from deep 
4-124 Gulf of Mexico Multisale EIS

hydrocarbon sources through subsurface conduits tends to be focused through the sediments, 

carbonate outcrops, and hydrate deposits at the seafloor. Therefore, GOM hydrocarbon seep 

communities tend to be larger (a few hundred meters wide) than chemosynthetic communities found 

around the hydrothermal vents of the Eastern Pacific (MacDonald, 1992).

As of 2015, at least 330 chemosynthetic communities have been confirmed (by government, 

academia, and industry) to exist in the Gulf of Mexico (Figure 4-11). Chemosynthetic communities 

dependent on hydrocarbon seepage have been documented in water depths as shallow as 951 ft 

(290 m) (Roberts et al., 1990) and at least as deep as 9,000 ft (2,743 m) (Roberts et al., 2010). But 

these known depth limits may only be reflective of the current limits of exploration due to the logistic 

difficulties of deepwater research; relatively few available submersibles are capable of exploring 

deeper than 3,281 ft (1,000 m). Given the rapid rate of discovery and improved understanding in 

recent years, the evidence suggests chemosynthetic communities could be more prevalent than 

once thought.

Figure 4-11. Estimated Distribution of Known Deepwater Benthic Communities in the Gulf of 

Mexico as of 2015.

Hydrocarbon seeps and chemosynthetic communities living on them modify the near-surface 

geological characteristics in ways that can be remotely detected, such as through 2D and 

3D seismic anomaly detection (USDOI, BOEM, 2015b). These known sediment modifications 

include the following: (1) precipitation of authigenic carbonate in the form of interstitial cements, 

micronodules, nodules, or rock masses; (2) formation of gas hydrates; (3) modification of sediment 

composition through concentration of hard chemosynthetic organism remains (such as shell 

fragments and layers); (4) formation of interstitial gas bubbles or hydrocarbons; and (5) formation of 
Description of the Affected Environment and Impact Analysis 4-125

depressions or pockmarks by gas expulsion. These features give rise to various detectable acoustic 

effects (details in Behrens, 1988; Roberts and Neurauter, 1990). Potential locations for most types 

of communities can be estimated by careful interpretation of these various geophysical modifications 

(Sager, 1997) and can help direct and focus follow-up visual surveys needed to definitively confirm 

the presence or absence of chemosynthetic communities.

BOEM’s subject-matter experts make use of the best available datasets to identify probable 

habitat that could support deepwater benthic communities. A primary such dataset is BOEM’s 

publicly available database of water-bottom anomalies (USDOI, BOEM, 2015b). Using decades of 

3D seismic amplitude data, BOEM geoscientists have identified and mapped over 31,000 waterbottom (seafloor) acoustic amplitude anomalies covering a majority of the deep waters in the 

northern Gulf of Mexico (Figure 4-12). One of the purposes of this effort is to better understand the 

distribution of natural hydrocarbon seeps and related chemosynthetic communities and deepwater 

coral communities. The areas of anomalously high or low seafloor reflectivity have been classified 

into general categories of seafloor features, including those that are thought to support 

chemosynthetic and deepwater coral communities (USDOI, BOEM, 2015b). As of 2015, BOEM was 

aware of a total of 332 seep anomalies that have been visually confirmed through photography, 

video, and manned submersible dives to contain associated chemosynthetic and/or coral 

communities (Figure 4-12, shown in orange); however, that relatively low number is largely due to a 

lack of visual survey effort required for definitive visual confirmation. Several of the other anomaly 

categories may also contain potential habitat capable of supporting deepwater chemosynthetic and 

coral communities. Additional information is being collected and analyzed by BOEM’s geoscientists 

and provided to BOEM’s subject-matter experts on an ongoing basis.

Figure 4-12. BOEM’s Water Bottom Seismic Anomaly Database Showing Grouped Anomaly 

Categories Thought Likely to Support Deepwater Benthic Communities (shown 

in orange) and Those That Generally Do Not (shown in purple)
4-126 Gulf of Mexico Multisale EIS

Biology

MacDonald et al. (1990) described four general community types: (1) tube worms; 

(2) mussels; (3) clams at the seafloor surface; and (4) burrowing clams. These faunal groups tend 

to display distinctive characteristics in terms of how they aggregate, the size of aggregations, the 

geological and chemical properties of the habitats in which they occur, and (to some degree) the 

heterotrophic fauna associated with them. Individual tube worms can reach lengths of over 10 ft 

(3 m) and live hundreds of years (Fisher et al., 1997). Average growth rates determined from 

marked tube worms have been variable, but they average approximately 7.1 millimeters/year 

(0.28 inches/year) for some species. Tube worm spawning and recruitment is episodic. Mytilid 

mussels have been found to reach reproductive age relatively quickly, with growth rates slowing in 

adulthood (Fisher, 1995). These factors lead to long-lived individuals and communities. Powell 

(1995) estimated that some clam and mussel communities at chemosynthetic sites have been 

present in the same location for between 500 and 4,000 years, with most communities showing no 

evidence of changes in the dominant faunal organisms over time. Local extinctions and 

recolonizations are likely gradual and rare.

Other common heterotrophic organisms often found at chemosynthetic community sites 

include a variety of mollusks, crustaceans, and echinoderms (Carney, 1993). Extensive mats of 

free-living bacteria are also evident at hydrocarbon seep sites. These bacteria may compete with 

the major fauna for sulfide and methane energy sources and may also contribute substantially to 

overall production (MacDonald, 1998). Some of the species found at GOM seep communities are 

new to science and remain undescribed.

Persistence

According to Sassen (1998), the role of naturally occurring methane hydrates to influence the 

morphology and characteristics of chemosynthetic communities has been greatly underestimated. 

Gas hydrates are a unique and poorly understood class of chemical substances. The dynamics of 

hydrate alteration could play a major role in the release of hydrocarbon gases to fuel biogeochemical 

processes and could influence community stability (MacDonald, 1998). Changes in bottom-water 

temperature of several degrees (39-41 °F [4-5 °C] at 1,640-ft [500-m] depth) may result in 

dissociation of hydrates and an accompanying increase in gas fluxes (MacDonald et al., 1994). 

Although not as destructive as the volcanism at vent sites o° the mid-ocean ridges, the dynamics of 

shallow hydrate formation and movement could clearly affect sessile animals around the seepage 

barrier because of the potential for an entire layer of shallow hydrate to break free of the bottom, 

which would result in considerable impacts to local communities of chemosynthetic fauna. At deeper 

depths (>3,281 ft; >1,000 m), the bottom-water temperature is colder and undergoes less fluctuation.

Precipitation of authigenic carbonates and other geologic events would alter surface 

seepage patterns and available substrates over periods of only a few years. However, through 

taphonomic (death assemblages of shells) studies and interpretation of seep assemblage 

composition from cores, Powell (1995) reported that, overall, seep communities were persistent over 

periods of 500-4,000 years. Powell found few cases in which the community type changed (from 
Description of the Affected Environment and Impact Analysis 4-127

mussel to clam communities, for example) over time. When recovery occurred after a past 

destructive event, the same chemosynthetic species reoccupied a site. MacDonald et al. (1995) 

observed no changes in chemosynthetic fauna distribution or composition at seven separate study 

sites. In the case of one well-known chemosynthetic community (Bush Hill), no mass die-offs or 

large-scale shifts in faunal composition were observed over 12 years of research.

4.4.1.2 Deepwater Coral Communities

Deepwater corals are sessile invertebrates in the phylum Cnidaria. They live at great depths 

(as deep as 10,000 ft [3,048 m] in some cases) where there is little to no light. As with the better 

known shallow-water corals, deepwater corals are colonial animals. Individual polyps extend 

tentacles into passing currents to feed on nutrients, which can be relatively scarce at depth. Energy 

supply is further limited by the lack of light-dependent mutualistic zooxanthellae algae that benefit 

many shallow-water coral species. As a result, deepwater coral colonies grow very slowly; colonies 

may live to be hundreds or even thousands of years old (USDOC, NOAA, 2014a).

Deepwater corals are found in all the world’s oceans and actually have a higher overall 

diversity of species than shallow-water coral (Cairns, 2007). Yet it is only in recent decades that 

they have become a focus of scientific research (Freiwald et al., 2004) and management concern 

(USDOC, NOAA, 2014a; CSA, 2002), as anthropogenic threats such as bottom disturbance (e.g., 

from fishing gear) have become more clear. Their very slow growth rates and fragile skeletal 

structures make them especially vulnerable to physical disturbance. Once damaged, deepwater 

corals and the associated communities they support may take centuries to fully recover (USDOC, 

NOAA, 2014a), which is why mitigation efforts aim to prevent any direct physical contact.

In the GOM, almost all deepwater corals are found attached to exposed surfaces of hard 

substrates. These substrates include chemosynthetically produced carbonate substrates (Chapter 

4.4.1.1), but they can also include exposed sedimentary bedrock and even artificial structures such 

as shipwrecks and oil platforms.

Some species of deepwater corals and sponges are known to create large, threedimensional structures, which are sometimes referred to as deepwater reefs. Some of these have 

grown many feet tall over time. Structure-forming corals include branching scleractinian species, 

Antipatharians (black corals) and gorgonians (sea whips/sea fans). Lophelia pertusa, the most wellknown scleractinian deepwater coral, can form vast reef-like thickets that can stretch to over 3,280 ft 

(1,000 m) in surface extent. In a historic 1955 trawl collection from a depth of 1,381-1,680 ft 

(421-512 m), Moore and Bullis (1960) retrieved more than 300 pounds (136 kilograms) of Lophelia 

pertusa from the Viosca Knoll area in the CPA.

Similar to shallow-water live bottom microhabitats (Chapter 4.6), deepwater coral 

microhabitats enhance the structural complexity of the local environment, providing shelter, feeding 

sites, and nursery grounds that are attractive to a large variety of other invertebrates and fishes, 

including a few commercially harvested species (Schroeder et al., 2005; Fisher et al., 2007; Fraser 
4-128 Gulf of Mexico Multisale EIS

and Sedberry, 2008; Sulak et al., 2008; Cordes et al., 2008; USDOC, NOAA, 2014a; Hourigan, 

2014). Common crustaceans include golden crab (Chaceon fenneri) and squat lobster (Eumunida 

picta). Common echinoderms include brittle stars (order Ophiurida) and baskets stars (order 

Euryalida). Deepwater reef-associated fish are known to include barrelfish (Hyperoglyphe 

perciformis), wreckfish (Polyprion americanus), and snowy grouper (Epinephelus niveatus) at 

shallower locations and blackbelly rosefish (Helicolenus dactylopterus), roughys (Hoplotsethus spp.), 

and thornyheads (Sebastolobus spp.) at deeper sites (Hourigan, 2014; refer to Chapter 4.7).

Distribution

Distribution of individual deepwater coral and associated species assemblages is influenced 

by depth, available substrate, and other environmental conditions such as bottom currents. At least 

six different types of octocoral assemblages occur in the deep northwestern Gulf and the West 

Florida Slope at depths of 820-8,200 ft (250-2,500 m). The black coral, Leiopathes spp., appears 

broadly distributed across both regions. Although Lophelia pertusa is best represented in water 

depths of the upper slope, it has occasionally been reported as deep as 9,842 ft (3,000 m) in some 

parts of the world.

The NOAA’s Deep Sea Coral Research and Technology Program and NOAA’s National 

Centers for Coastal Ocean Science have been continuously compiling a detailed national database 

of known observations of deepwater corals and sponges (USDOC, NOAA, 2014a and 2015j) 

(Figures 4-10 and 4-11), but these confirmed visual observations likely represent only a fraction of 

the populations. Deepwater research cruises, for example those undertaken by NOAA’s deep-sea 

research vessel Okeanos Explorer, routinely discover additional deepwater coral locations. 

However, even with ongoing additions of observation records, the majority of deepwater coral 

communities would not be directly observed and documented in the near future due to the inherent 

logistical difficulties of deepwater research and data collection.

Therefore, extrapolative analyses such as one undertaken by NOAA (Figure 4-13) have also 

included efforts to predictively model suitable habitat for deepwater coral and sponges, based on 

existing observation records combined with the best available physical datasets. These models can 

serve as an important tool to help identify where deepwater coral communities are likely to be found 

and to help focus future data collection and research efforts. For example, based in part on previous 

databases and models, the Gulf of Mexico Fishery Management Council (GMFMC) is currently 

evaluating advisory panel recommendations to designate up to 47 new, small areas as deepwater 

coral Habitat Areas of Particular Concern (CSA, 2002). Future research, including a planned 

BOEM-funded study (Interagency Agreement #M15PG00020), may improve on previous deepwater 

coral modeling and expand to include chemosynthetic communities. 
Description of the Affected Environment and Impact Analysis 4-129

Figure 4-13. Example of a Predictive Habitat Suitability Model for Selected Deepwater, 

Framework-Forming Scleractinian Corals (excerpted with permission from 

USDOC, NOAA, 2014a).

4.4.2 Environmental Consequences 

4.4.2.1 Routine Activities 

A number of routine OCS oil- and gas-related impact-producing factors may cause adverse 

impacts to deepwater benthic communities. As noted above, some factors with only minimal 

impacts are presented in greater detail in other chapters, and full analyses are not repeated here. 

The potential routine impact-producing factors on deepwater benthic habitats analyzed here are 

grouped into two main categories having similar impacts: (1) bottom-disturbing activities; and 

(2) drilling-related sediment and waste discharges. These impact-producing factors have the 
4-130 Gulf of Mexico Multisale EIS

potential to damage deepwater benthic habitats and disrupt associated communities if not 

sufficiently distanced via mitigations. 

Bottom-Disturbing Activities

Bottom-disturbing activities can be described as any activities that result in the physical 

disturbance of the seafloor during the exploration, production, or decommissioning phase of OCS 

operations (refer to Chapters 3.1.2, 3.1.3.3, and 3.1.6). Anchoring, drilling, trenching, pipe-laying, 

and structure emplacement and removal are examples of OCS oil- and gas-related activities that 

disturb the seafloor (refer to Chapters 3.1.3.3 and 3.1.6). The spatial extent of the seafloor 

disturbance and the magnitude of the effect on deepwater benthic organisms would depend on the 

specific activity, local environmental conditions (e.g., currents, water depth, etc.), and speciesspecific behaviors and habitat preferences.

Turbidity from suspended sediments, along with sediment displacement resulting from 

routine, bottom-disturbing oil- and gas-related activities, generally has localized effects. Impacts to 

deepwater benthic communities could include any or all of the following: reduced settlement and 

growth opportunities due to loss of available hard substrate; inhibited feeding leading to reduced 

reproductive fitness; and mortality of individuals (e.g., coral polyps and 1 or 2 tubeworms) and 

groups (e.g., entire coral colonies and tubeworm “bushes”). Reductions in overall biological cover 

could have secondary ecological effects on organisms that were using the complex structural 

microhabitats, for example the loss of a shark spawning ground (some sharks deposit eggs in 

deepwater coral [Etnoyer and Warrenchuk, 2007]) that reduces future shark populations. Some 

mobile invertebrates (e.g., brittle stars) are expected to be able to move to avoid the heaviest 

sediment displacement and highest suspended sediment loads within 33 ft (10 m) of a disturbance, 

while sessile invertebrates (e.g., corals) cannot. Sessile and mobile invertebrate species adapted to 

living in turbid environments, such as many gorgonians, may be less affected by increased turbidity. 

Such organisms may also be adapted to remove some covering sediment via tentacle motion and 

mucus secretion (Shinn et al., 1980; Hudson and Robbin, 1980). Other species that typically inhabit 

less turbid waters would suffer relatively greater impacts (Rogers, 1990; Gittings et al., 1992a). 

Solitary octocorals and gorgonians may be tolerant of a certain amount of sedimentation, partly 

because they grow tall and are flexible, reducing sediment accumulation and allowing for easier 

removal (Marszalek, 1981; Torres et al., 2001; Gittings et al., 1992a), but are not completely resilient 

to impacts (Doughty et al., 2014).

The OCS oil- and gas-related infrastructure/equipment also has the potential to damage or 

kill deepwater benthic organisms should the equipment itself make direct contact. Any object placed 

on or through (e.g., a piston-driven core sampler) a deepwater benthic organism or supporting 

substrate can cause partial or complete breakage, crushing, or smothering. In addition to mortality, 

there could be any or all of the potential sublethal impacts already described above in relation to 

turbidity and sediment displacement. The severity of community impacts from direct physical 

contact would vary in direct proportion to the surface area and mass of the specific equipment. For 
Description of the Affected Environment and Impact Analysis 4-131

example, the placement of a large bottom-founded platform on a deepwater benthic community 

would have a much greater impact than placement of a small umbilical cable.

Similarly, anchor damage is one of the greatest threats to benthic biota in the GOM if it is not 

prevented (Rezak and Bright, 1979; Rezak et al., 1985; Gittings et al., 1992a; Hudson et al., 1982). 

Anchors may break, fragment, or overturn tubeworms, bivalves, corals, sponges, or any other 

sessile benthic organisms, and the anchor chain or cable may drag across and shear organisms off 

the substrate (Dinsdale and Harriott, 2004). This would result in consequences ranging from 

increased stress to mortality (Dinsdale and Harriott, 2004). The impact of dragging an anchor 

across a deepwater benthic community would depend on the distance and duration of bottom 

contact, but it could be considerable due to the forces involved; dragged anchors often leave 

seafloor scars noticeable on sidescan sonar imagery years later. Damage to a coral community may 

take decades to recover (Fucik et al., 1984; Rogers and Garrison, 2001).

Drilling-Related Sediment and Waste Discharges

Drilling of new wells is one of the activities with the greatest impact potential due to the 

associated sedimentation/turbidity caused by the drilling process and from the release of drilling 

cuttings and discharges (Chapter 3.1.5.1). Drilling an exploratory well produces approximately

2,000 metric tons of combined drilling fluid and cuttings, though the total mass may vary widely for 

different wells (Neff, 2005). Cuttings discharged at the surface tend to disperse in the water column 

and be distributed at low concentrations (CSA, 2004a). In deep water, the majority of cuttings 

discharged at the sea surface are likely to be deposited within 820 ft (250 m) of the well (CSA, 

2006). Cuttings shunted to the seafloor form piles concentrated within a smaller area than do 

sediments discharged at the sea surface (Neff, 2005).

Apart from the direct impacts of turbidity and sedimentation, the chemical content of drilling 

muds and cuttings (and, to a lesser extent, produced waters) are another potential impact-producing 

factor since these may contain hydrocarbons, trace metals including heavy metals, elemental sulfur, 

and radionuclides (Kendall and Rainey, 1991; Trefry et al., 1995). Substances containing heavy 

metals and other potentially toxic compounds would have the potential to be moderately toxic to 

deepwater benthic organisms, but only if they were to come into contact in undiluted strengths (CSA, 

2004b). Although the literature has not reported impacts to chemosynthetic organisms, gorgonians, 

or soft corals as a result of exposure to contaminants in cuttings, infauna have shown effects at 

distances <330 ft (<100 m) from the discharge. These include reduced reproductive fitness, altered 

populations, and acute toxicity (Montagna and Harper, 1996; Carr et al., 1996; Kennicutt et al., 1996; 

Hart et al., 1989; Chapman et al., 1991; CSA, 2004b). Because of BOEM’s distancing requirements 

for new wells, contact with concentrated (and potentially harmful) levels of any such toxins is not 

expected. As they travel from a source, produced waters (refer to Chapter 3.1.5.1.2 for more detail) 

are rapidly diluted with distance, and impacts are generally only observed within very close proximity 

of the discharge point (Gittings et al., 1992a; Neff, 2005). In addition to the protection offered by 

BOEM’s distancing requirements, releases of toxic discharges are regulated by the USEPA through 
4-132 Gulf of Mexico Multisale EIS

the issuance of NPDES permits. Adherence to these regulations would help ensure that water 

quality is maintained at nontoxic levels.

In addition to drilling activities, the process of installing and removing OCS oil- and gasrelated infrastructure (i.e., pipelines, platforms, and subsea systems including cables) also has the 

potential to displace large volumes of sediment (Chapters 3.1.3.3 and 3.1.6). The resulting 

localized increases in turbidity and sedimentation would have the same indirect impacts as those 

caused by drilling-related sediment movement.

As further detailed in other chapters, explosive severance methods used during 

decommissioning activities could result in damage or mortality to any organisms within the vicinity of 

the blast or associated sediment plume, although long-term turbidity is not expected from platform 

removal operations. The shockwave from a nearby blast could also damage or destroy the 

underlying hard substrates required to support some deepwater benthic communities. The BSEE 

Interim Policy Document 2013-07, “Rigs-to-Reefs Policy,” specifies that the use of explosive 

severance methods would not be approved if site-specific analysis determines they would cause 

harm to natural deepwater benthic communities.

Compared with shallow-water live bottom communities, some deepwater benthic organisms 

may be slower to recover from any of the impacts described above due to the generally much slower 

growth and recruitment rates that are typical of these longer-lived species and communities (Powell, 

1995). For example, Doughty et al. (2014) demonstrated that Paramuricea spp., some of the most 

common deepwater corals in the GOM, may have very low recruitment rates and therefore slow 

recovery.

Potential impacts resulting from all of the above routine activities (both bottom-disturbing 

activities and drilling-related sediment and waste discharges) are mitigated through the protective 

measures (primarily distancing) described above and in NTL 2009-G40. The postlease, site-specific 

survey information and mitigation options described in NTL 2009-G40 would allow BOEM to identify 

and sufficiently distance deepwater benthic features from any proposed OCS oil- and gas-related 

routine activity during postlease reviews. If all of these requirements are applied as expected, at the 

scope of this analysis, the impacts of routine activities would be expected to be negligible. 

Without adherence to those requirements or absent expected USEPA restrictions on 

discharges, impacts to deepwater benthic communities from the above routine activities could rise to 

minor, moderate, or even major, depending on the number and locations of specific activities. The 

highest impact levels are possible in the improbable (but theoretically possible) case that a large 

number of routine activity disturbances were to physically impact a large number of deepwater 

benthic communities. Even without mitigations, the likelihood is very low that a large number of 

OCS oil- and gas-related activities would occur in close proximity because the hard substrate 

habitats supporting deepwater benthic communities are patchily distributed throughout the GOM and 

are relatively rare compared with soft bottom substrates. But this possibility cannot be definitively 
Description of the Affected Environment and Impact Analysis 4-133

ruled out without knowing both the precise spatial distribution of both future OCS oil- and gas-related 

activities and deepwater benthic communities.

4.4.2.2 Accidental Events

The primary accidental impact-producing factors affecting deepwater benthic communities 

analyzed here are grouped into two categories: (1) bottom-disturbing activities; and (2) oil spills and 

associated cleanup responses. These factors have the potential to damage deepwater benthic 

habitats and disrupt associated benthic communities if not sufficiently distanced or otherwise 

mitigated.

Bottom-Disturbing Activities

Impacts resulting from bottom-disturbing activities were already detailed in “Routine 

Activities” section above and are largely the same for accidental events. There are only slight 

differences that need to be considered here and are related to mechanisms and potential severity. 

The primary, accidental bottom-disturbing activity is the inadvertent deposition or placement of 

equipment on deepwater habitats. Accidental loss of equipment could occur during transfer 

operations between vessels and platforms, during vessel transit, during an “on deck” accident, as a 

consequence of a severe storm, or if a structure, drill, or anchor is unintentionally placed in the 

wrong location during operations. During routine operations, the distancing mitigations offer some 

protections against these types of impact, but those protections may not apply to all accidents, other 

than to reduce the likelihood of routine activities occurring in those areas in the first place. Any 

object placed on or through a deepwater benthic habitat could cause partial or complete breakage, 

crushing, or smothering of both substrate and organisms, and/or increased sedimentation as 

equipment disturbs the seafloor. In addition to mortality, deepwater benthic communities could 

experience any or all of the potential sublethal impacts already described in the “Routine Activities” 

section above. The severity of impacts from direct physical contact would vary in direct proportion to 

the surface area and mass of the specific equipment. Given the relative rarity of deepwater benthic 

habitats and communities in the GOM, accidental impacts from bottom-disturbing equipment are 

expected to be infrequent and highly localized, with the likelihood of accidental contact further 

reduced by the expected distancing mitigations. However, because of the unplanned and potentially 

uncontrolled nature of accidental bottom-disturbing events, there exists greater uncertainty about 

their potential impact severity than exists for planned routine activities. Therefore, at the scale of this 

analysis, impacts to deepwater benthic communities from accidental, bottom-disturbing activities 

could range from negligible to minor, depending on their overall frequency and severity and 

whether or not community-level accidental impacts can be clearly distinguished from natural 

variation.

Without the protective mitigations provided by postlease reviews and distancing, the potential 

impacts of accidental bottom disturbances could rise to moderate or even major levels, in the 

improbable (but theoretically possible) case that a large number of accidental disturbances were to 

physically impact a large number of deepwater benthic communities. Even without mitigations, the 

likelihood is very low that a large number of OCS oil- and gas-related activities would occur in close 
4-134 Gulf of Mexico Multisale EIS

proximity to the relatively rare hard substrate habitats supporting deepwater benthic communities. 

However, this possibility cannot be definitively ruled out without knowing both the precise spatial 

distribution of both future OCS oil- and gas-related activities and deepwater benthic communities.

Oil Spills and Associated Cleanup Responses

Oil spills, historic trends, the characteristics of oil, and factors affecting the fate of oil 

released into the marine environment are discussed in detail in Chapter 3.2.1 (Oil Spills), and the 

potential impacts to water quality are analyzed in Chapter 4.2 (Water Quality). For additional 

information on impacts resulting specifically from a catastrophic spill, refer to the Catastrophic Spill 

Event Analysis white paper (USDOI, BOEM, 2017).

Impacts related to an accidental release of oil or other contaminants could adversely affect 

deepwater benthic communities. Potential impacts related to an accidental spill would depend on 

the combination of these various components: surface oil; subsurface oil; chemical dispersants and 

dispersed oil; sedimented oil (oil adsorbed to sediment particles); sedimentation caused by a loss of 

well control; and certain spill-response activities. Adherence to well-distancing requirements should 

serve to reduce such impacts.

Biological impacts resulting from exposure to accidentally released oil droplets and/or 

chemical dispersants are anticipated to be mostly sublethal and recoverable. Sublethal impacts that 

may occur to exposed deepwater benthic organisms may include reduced feeding, reduced 

reproduction and growth, physical tissue damage, and altered behavior. For example, short-term, 

sublethal responses of a shallow-water coral species included mesenterial filament extrusion, 

extreme tissue contraction, tentacle retraction, and localized tissue rupture reported after 24 hours of 

exposure to dispersed oil at a concentration of 20 ppm (Knap et al., 1983; Wyers et al., 1986). 

Laboratory tests by DeLeo et al. (2015) on the relative effects of oil, chemical dispersants, and 

chemically dispersed oil mixtures on three species of northern GOM deepwater corals found much 

greater health declines in response to chemical dispersants and to oil-dispersant mixtures than to 

oil-only treatments, which did not result in mortality. It is important to note that, generally, laboratory 

experimental concentrations are designed to discover toxicity thresholds (as in DeLeo et al., 2015) 

that exceed probable exposure concentrations in the field.

Chemosynthetic organisms are naturally adapted to handle the limited amounts of 

hydrocarbons that are typical at slow-flowing seeps. While they have not been as well studied as 

deepwater corals, there have not been documented impacts from the Deepwater Horizon oil spill to 

chemosynthetic communities (USDOI, BOEM, 2012b; Shedd, official communication, 2015). It is 

possible that some deepwater coral species also have limited capabilities to endure oil exposure. 

Results from DeLeo et al. (2015) suggested that Callogorgia delta, a soft coral often associated with 

natural hydrocarbon seeps, may have some natural adaptation to short-term oil exposure. 

Al-Dahash and Mahmoud (2013) suggest that a possible mechanism for this is coral harboring of 

symbiotic oil-degrading bacteria. Oil spills originating at the surface have fairly limited potential to 

directly impact deepwater benthic communities. Oil becomes diluted as it physically mixes with the 
Description of the Affected Environment and Impact Analysis 4-135

surrounding water and moves into the water column, and the physical mixing zone of surface oil is 

generally limited to approximately 33 ft (20 m) (Lange, 1985; McAuliffe et al., 1975 and 1981a; 

Tkalich and Chan, 2002; Thompson et al., 1999; Schroeder, 2000). In one extraordinary 

circumstance with an unusual combination of conditions, a tropical storm forced a large volume of 

Deepwater Horizon oil spill-linked dispersant/oil mixture as deep as 246 ft (75 m), causing temporary 

exposure to mesophotic corals in the Pinnacle Trend area (Silva et al., 2015), but that depth is still 

far shallower than that of the deepwater benthic communities considered here.

The USCG may allow the application of chemical dispersants in certain spill situations. 

Chemical dispersion of oil can help to break up concentrations of oil, accelerate natural weathering 

processes, and promote bacterial biodegradation (Chapter 3.2.8). Use of dispersants may, 

however, have unintended effects. For example, it may allow surface oil to penetrate to greater 

depths than expected from normal physical mixing, and dispersed oil more often remains below the 

water’s surface (McAuliffe et al., 1981b; Lewis and Aurand, 1997), possibly leading to negative 

impacts such as those observed by Silva et al. (2015). DeLeo et al. (2015) demonstrated that 

concentrated amounts of dispersant and oil/dispersant mixtures caused more severe health declines 

to deepwater coral than oil-only mixtures.

In a subsurface spill or loss of well control situation, it is expected that the majority of 

released oil would rise quickly to the surface due to the characteristics of northern GOM oil reserves. 

However, if an oil spill occurs at great depths and is subjected to higher water pressures, some oil 

droplets may emulsify and become entrained deep in the water column (Boehm and Fiest, 1982), 

creating a subsurface plume (Adcroft et al., 2010). During the Deepwater Horizon oil spill, 

dispersants were applied subsea at the source of the blowout. Stratified density layers of water 

allowed the oil/dispersant plume to remain at depth instead of dispersing up into the water column 

(Joint Analysis Group, 2010), and these concentrated plumes likely contributed to the serious (but 

localized) damage to deepwater coral communities. If a concentrated plume comes into continuous 

contact with a deepwater benthic community, the general impacts could include mortality, tissue 

loss, opportunistic hydroid overgrowth, failed reproductive success, reduced biodiversity, reduced 

coverage of fauna and flora on hard substrates, and changes in community structure (White et al., 

2012; Hsing et al., 2013; Fisher et al., 2014a; Silva et al., 2015). Exact impacts would depend on 

the location, age of the spill, and the hydrographic characteristics of the area. Adherence to the 

distancing requirements described above and in NTL 2009-G40 should reduce such impacts.

For any accidental spill, it is expected that a certain quantity of oil may eventually settle on 

the seafloor through a binding process with suspended sediment particles (adsorption) or after being 

consumed and excreted by phytoplankton (Passow et al., 2012, Valentine et al., 2014) (refer to the 

Catastrophic Spill Events Analysis white paper for larger events that are not considered reasonably 

foreseeable [USDOI, BOEM, 2017]). The product of these processes is sometimes referred to as 

“marine snow.” It is expected that the greatest amount of adsorbed oil particles would occur close to 

the spill, with the concentrations reducing over distance. Adherence to the original well distancing 

requirements should therefore reduce such impacts. 
4-136 Gulf of Mexico Multisale EIS

If a spill does occur close to a deepwater benthic habitat, some of the organisms may 

become smothered by marine snow particles and/or other sediments, and experience long-term 

exposure to hydrocarbons and/or oil-dispersant mixtures that could persist within the sediments 

(Hsing et al., 2013; Fisher et al., 2014a; Valentine et al., 2014). White et al. (2014) found the anionic 

surfactant DOSS (dioctyl sodium sulfosuccinate) persisting for at least 6 months within a deepwater 

coral community, although that study did not measure toxicity. Krasnec et al. (2015) did measure 

toxicity of sediments collected within 2 km (1.2 mi) of the Macondo wellhead, but they did not 

measure the effects on deepwater megafauna. The study found varying levels of mortality and 

growth inhibition for a small shrimp-like crustacean species, with the relative degree of toxicity 

decreasing over time (lower toxicity found in 2014 samples than in 2011 samples). Beyond the 

localized area of impact in such cases, particles would become increasingly biodegraded and 

dispersed. Localized impacts to deepwater benthic organisms from marine snow would be expected 

to be mostly sublethal and could include reduced recruitment success, reduced growth, and reduced 

biological cover as a result of impaired recruitment (Rogers, 1990; Kushmaro et al., 1997).

Sediments suspended or displaced as a result of a loss of well control could also impact 

deepwater benthic organisms. These impacts would be largely identical to those caused by 

sedimentation stirred up by bottom-disturbing equipment, with the possible addition of toxic 

hydrocarbons or drilling muds in the sediments (refer to “Routine Activities” above). Because OCSpermitted wells would have been distanced from deepwater benthic habitats before installation, it is 

expected that the heaviest sediment concentrations would fall out of suspension and disperse before 

reaching sensitive benthic communities, preventing most impacts. Some live bottom organisms, 

such as flexible sea fans, are naturally adapted to turbid conditions and may not be as negatively 

affected. Outside of a catastrophic blowout situation, a very substantial amount of sediment burial of 

organisms during an accidental spill event is not considered reasonably foreseeable (refer to the 

Catastrophic Spill Events Analysis white paper, USDOI, BOEM, 2017).

Finally, spill cleanup/response activities could themselves have negative impacts (Chapter 

3.2.8). During a response operation, the risk of accidental impacts of bottom-disturbing equipment is 

increased. There could be unplanned emergency anchoring or accidental losses of equipment from 

responding vessels. Response-related equipment such as seafloor-anchored booms may be used 

and could inadvertently contact deepwater habitats and organisms. In addition, drilling muds may be 

pumped into a well to stop a loss of well control. It is possible that during this process some of this 

mud may be forced out of the well and deposited on the seafloor near the well site. If this occurs, 

the impacts would be severe for any organisms buried; however, the impact beyond the immediate 

area would be limited and adherence to the original distancing requirements should prevent or 

reduce most impacts.

Accidental spills have historically been small and relatively rare events (Chapters 3.2.1.4, 

3.2.1.5, and 3.2.1.6; Table 3-12). The total number of deepwater benthic communities is relatively 

small and they are widely distributed throughout the AOI, so a localized impact from one 

noncatastrophic accidental event would only impact a small portion of the overall resource.
Description of the Affected Environment and Impact Analysis 4-137

All of these oil spill and associated cleanup response activities could lead to lethal or 

sublethal impacts on individual deepwater benthic communities, with the range of impacts 

dependent on the quantity of spilled oil and proximity to habitats. While a spill resulting from a 

catastrophic-level blowout in deep water (such as the Deepwater Horizon oil spill) has the potential 

to seriously impact individual deepwater benthic communities over a long time period, such a spill is 

not considered reasonably foreseeable as a result of a proposed lease sale. Impacts from individual 

routine activities and reasonably foreseeable accidental events are usually temporary, highly 

localized, and expected to impact only small numbers of organisms and substrates at a time. 

Natural adaptations to small quantities of oil (Al-Dahash and Mahmoud, 2013; DeLeo et al., 2015) 

and/or recovery over time (Hsing et al., 2013) is possible for certain deepwater benthic species. 

Moreover, use of the expected site-specific plan reviews/mitigations would distance activities from 

deepwater benthic communities, greatly diminishing the likelihood and severity of potential effects. 

Therefore, at the scale of this analysis and with application of the expected mitigation practices, 

impacts on deepwater benthic communities from accidental spills are expected to range from 

negligible to minor. This range of potential impact levels reflects the relative uncertainty associated 

with unplanned and potentially uncontrolled accidental events and the uncertainty about the precise 

distribution of deepwater benthic communities. The exact impact would depend on overall 

frequency, extent, and severity of accidental spills and whether or not community-level accidental 

impacts can be clearly distinguished from natural variation.

Without the protective mitigations provided by postlease reviews and distancing, the potential 

impacts of accidental spills could rise to moderate or even major levels, in the improbable (but 

theoretically possible) case that a large number of accidental spills were to occur at wells in close 

proximity to a large number of deepwater benthic communities. Even without mitigations, the 

likelihood is very low that a large number of accidental spills would occur in close proximity to the 

relatively rare hard substrate habitats supporting deepwater benthic communities, but this possibility 

cannot be definitively ruled out without knowing both the precise distribution of such spills and of 

deepwater benthic communities.

4.4.2.3 Cumulative Impacts

Cumulative impacts on deepwater benthic communities are of concern in part because of 

their very slow growth rates, which may increase their vulnerability to disturbance over time (Prouty 

et al., 2014). This analysis considers the cumulative impacts on deepwater benthic communities 

resulting from (1) the incremental impacts from future routine and accidental oil- and gas-related 

operations from a proposed lease sale, as well as those resulting from past and future OCS leasing; 

and (2) potential impacts stemming from other non-OCS oil- and gas-related factors.

OCS Oil- and Gas-Related Impacts

The Cumulative OCS Oil and Gas Program (Chapter 3.3.1) impacts to deepwater benthic 

communities include the incremental contribution of the routine and accidental bottom-disturbing 

activities outlined above: (1) bottom-disturbance; (2) sediment and waste discharges; and 

(3) accidental oil spills. As already detailed, these impact-producing factors have the potential to 
4-138 Gulf of Mexico Multisale EIS

damage individual deepwater habitats and disrupt associated benthic communities if insufficiently 

distanced or otherwise mitigated.

Bottom-disturbing activities could result in the physical destruction of benthic habitat and 

organisms or the disturbance of sediments within the environment, resulting in partial or complete 

burial and/or increased turbidity (Chapter 3.3.1.5). Routine and accidental waste discharges could 

be toxic if contacted in undiluted form near the source, but that is generally unlikely.

Oil spills and chemical dispersants are known to have negative, acute effects on deepwater

benthic organisms such as corals (e.g., DeLeo et al., 2015). The cumulative, long-term effects of 

persistent, low-level exposure to oil are not yet fully understood, although such research is ongoing 

following the Deepwater Horizon oil spill (e.g., White et al., 2014; Baguley et al., 2015). All of these 

activities could lead to lethal or sublethal impacts on individual deepwater benthic communities. 

Although a spill resulting from a catastrophic-level blowout in deep water, such as Deepwater 

Horizon blowout (refer to the Catastrophic Spill Events Analysis white paper, USDOI, BOEM, 2017), 

has the potential to seriously impact individual deepwater benthic communities over a long time 

period (Hsing et al., 2013), the spatial extent of impacts from even such a large spill remains 

relatively limited (Montagna et al., 2013; Fisher et al., 2014b) and the probability of additional 

catastrophic-level spills of that size is low.

Impacts from these individual routine activities and accidental events are usually temporary, 

highly localized, and expected to impact only small numbers of organisms and substrates at a time. 

Recovery over time from such impacts is possible for certain species (e.g., Hsing et al., 2013). 

Moreover, use of the expected site-specific plan reviews/mitigations would distance activities from 

deepwater benthic communities, greatly diminishing potential effects. Therefore, the cumulative 

contribution of all OCS oil- and gas-related activities is expected to have only negligible to minor

impacts while the much smaller incremental cumulative impact of a single proposed lease sale is 

expected to contribute only a negligible amount to the total level of cumulative impacts.

Non-OCS Oil- and Gas-Related Impacts

The cumulative, long-term impacts on deepwater benthic communities of reasonably 

foreseeable, non-OCS anthropogenic activities and shifting baseline environmental conditions could 

be substantial, although they are difficult to quantify, particularly when projecting future conditions 

out over the next 50 years. A brief summary analysis is provided here. It should be noted that 

BOEM’s site-specific mitigations are not designed to mitigate against the potential impacts posed by 

these non-OCS anthropogenic activities and environmental factors; they are designed to protect 

deepwater benthic resources from OCS oil- and gas-related activities within BOEM’s jurisdiction and 

to mitigate against any proposed action’s incremental contribution to the overall OCS and non-OCS 

cumulative impacts. 

The primary anthropogenic activities are related to commercial fishing (Chapter 4.10). 

Bottom-tending fishing gear of any type (e.g., trawls, traps, bottom-set longlines, and gillnets) can 
Description of the Affected Environment and Impact Analysis 4-139

affect deepwater benthic communities by dislodging or crushing organisms attached to the bottom, 

with trawls representing the most serious threat (Hourigan, 2014). Currently, the overall amount of 

fishing effort in very deep waters of the GOM is spatially and temporally limited and primarily 

consists of a relatively small royal red shrimp fishery and only sporadic reports of golden crab traps 

(CSA, 2002). Therefore, at the present time, commercial fishing impacts on GOM deepwater 

benthic communities are negligible. Should the overall amount of effort or types of gear used 

change dramatically over time, fishing impacts could become considerably greater, perhaps as great 

as major, although that theoretical impact level is highly speculative and dependent on unknown and 

perhaps improbable future changes in fishery practices.

Climate change-related effects have the potential to alter baseline environmental conditions 

in the GOM, including in deep waters. A review of climate change is presented in Chapter 4.2.1 of 

the Five-Year Program EIS (USDOI, BOEM, 2016b), and there is extensive scientific literature 

available about climate change in general. However, there is currently relatively little literature 

dedicated to the potential impacts on deepwater benthic communities. Of primary concern for 

deepwater benthic communities is a projected decline of ocean pH of 0.3-0.5 units over the next 

century, a shift which would significantly alter calcium carbonate saturation states in the ocean 

(Doney et al., 2009), reducing the bioavailability of calcium carbonate. Decreased calcification rates 

have been observed in numerous shallow-water zooxanthellate corals (refer to Hofmann et al., 

2010). Similar effects could be expected for deepwater corals such as Lophelia pertusa (Lunden 

et al., 2013; Lunden et al., 2014, Hennige et al., 2015) and for various other calcifying organisms in 

deep water (Thresher et al., 2015), and such effects could make it more difficult for deepwater 

calcifying organisms to form or maintain calcium carbonate-based skeletons or shells, possibly 

inhibiting growth. At the depths of these communities, little to no effect is expected from potential 

increases in storm frequency and intensity that could possibly be attributed to climate change. The 

cumulative impact level of future climate change-related factors is difficult to accurately estimate with 

the current level of scientific understanding. Important baseline data, such as basic measurements 

of aragonite saturation horizons, are still in the early years of collection and analysis, and the many 

unknown factors involved make it difficult to accurately assign an authoritative impact level for this 

impact-producing factor at the long-term scope of this analysis. At present, the overall impact of 

climate change-related effects on deepwater benthic communities is likely negligible. However, 

over the next 50 years, this impact level could rise to higher levels, even as great as major, should 

the most extreme impacts possible as a result of projected climate change-associated factors come 

to pass.

Incremental Contribution of a Single Proposed Lease Sale to Overall Cumulative Impacts

Weighed against these potential non-OCS oil- and gas-related impacts from anthropogenic 

activities and influential baseline environmental conditions, the much smaller incremental cumulative 

impact of a proposed lease sale is expected to contribute only a negligible amount to the total 

potential level of impacts. Based on current conditions, the overall cumulative impact of everything 

(OCS and non-OCS) is negligible to minor. This total impact level has the potential to rise over the 
4-140 Gulf of Mexico Multisale EIS

next 50 years to higher levels, even possibly major, should projected trends of non-OCS oil- and 

gas-related activities (particularly climate change) continue or worsen.

4.4.2.4 Incomplete or Unavailable Information

For decades, BOEM has funded research related to deepwater benthic environments in 

order to further the scientific understanding necessary for informed decisionmaking. However, due 

in part to the inherent difficulty of data collection in deepwater environments, there is (and likely 

always would be) incomplete or unavailable information about deepwater benthic communities. 

BOEM has specifically identified incomplete information for OCS oil- and gas-related impacts related 

to the following: locations of deepwater benthic communities in the GOM; toxicity of oil and 

dispersants to deepwater benthic organisms; long-term effects of the totality of the presence of OCS 

oil- and gas-related infrastructure; long-term effects associated with various climate change-related 

factors; cascading ecological effects and interactions between deepwater benthic communities and 

deepwater fish communities; and long-term impacts from the Deepwater Horizon explosion, oil spill, 

and response (refer to the Catastrophic Spill Events Analysis white paper, USDOI, BOEM, 2017).

As described above, BOEM’s databases of confirmed deepwater benthic communities and 

3D seismic water-bottom anomalies are used when reviewing deepwater exploration and 

development plans. As part of postlease, site-specific development plans, operators must provide a 

variety of high-resolution survey data, including assessments of potential habitat for sensitive benthic 

communities. If data are sparse or additional detail is needed, site-specific video or photographic 

surveys can be requested and used to develop appropriate mitigations. While extremely helpful, 

BOEM’s databases and survey data are not comprehensive of all deepwater benthic communities. 

For example, available information may not always be of sufficient resolution to identify small areas 

of scattered hard substrate, such as dead clam shells, that may support small patches of deepwater 

benthic habitat, as discussed by Quattrini et al. (2013).

To help fill data gaps about locations of deepwater benthic communities, BOEM may also be 

able to make use of additional datasets created by other Federal agencies. For example, NOAA’s 

Deep Sea Coral Research and Technology Program and NOAA’s National Centers for Coastal 

Ocean Science have been compiling a database of known observations of deepwater corals and 

sponges (USDOC, NOAA, 2015i). This database of confirmed deepwater coral observations could 

be used as an ancillary information source during site-specific plan reviews. However, even with the 

continued additions of observation records over time, it is unlikely that the majority of deepwater 

coral communities would be directly observed and documented because of the inherent logistical 

difficulties involved in deepwater research and data collection. Past research by NOAA (Kinlan 

et al., 2013) has also included efforts to predictively model suitable habitat for deepwater coral and 

sponges, based on the best available physical/environmental datasets. Future research may 

improve on these efforts and expand to include chemosynthetic communities. New datasets and 

models such as these, once they are complete, scientifically vetted, and publicly available, could 

provide helpful ancillary information to further assist BOEM’s site-specific evaluations.
Description of the Affected Environment and Impact Analysis 4-141

BOEM will continue to analyze and support the continued collection of the best available 

scientific information related to deepwater benthic communities. However, the best available 

information does not provide all of the data necessary for a complete understanding of these 

communities. For example, there is incomplete information with respect to potential long-term 

effects resulting from exposure to spilled oil, including potential impacts of a catastrophic spill such 

as the Deepwater Horizon oil spill. Known information about the potential impacts of a theoretical 

catastrophic spill is detailed in the Catastrophic Spill Events Analysis white paper (USDOI, BOEM, 

2017), and further information was made available with the publication of NOAA’s Deepwater 

Horizon Oil Spill: Final Programmatic Damage Assessment and Restoration Plan and Final 

Programmatic Environmental Impact Statement in 2016 (Deepwater Horizon Natural Resource 

Damage Assessment Trustees, 2016). The content of that report was reviewed as part of this

analysis. Some information related to impacts specific to the Deepwater Horizon explosion, oil, spill, 

and response, such as long-term monitoring results, is still incomplete or unavailable. Impending 

reports are not expected to reveal additional significant effects that would alter the overall 

conclusions about reasonably foreseeable impact-producing factors associated with a proposed 

lease sale. However, in completing this analysis and in making conclusions, BOEM used the best 

available science to determine the range of reasonably foreseeable impacts, applying accepted 

scientific methodologies to both integrate existing information and extrapolate potential outcomes. 

Therefore, BOEM has determined that the incomplete information is not essential to a reasoned 

choice among alternatives.

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

The activities proposed under Alternative A could directly impact deepwater benthic 

communities within the GOM. The primary, reasonably foreseeable impact-producing factors for 

deepwater benthic habitats can be grouped into three main categories: (1) bottom-disturbing 

activities; (2) sediment and waste discharges; and (3) oil spills. 

BOEM’s site-specific reviews of permit applications would, through distancing and other 

appropriate mitigations, greatly reduce potential impacts to deepwater benthic communities as a 

result of routine activities and accidental events. At the broad scope of this analysis, and assuming 

adherence to all expected postlease, protective restrictions and mitigations, the routine activities are 

expected to have largely short-term, localized and temporary effects on deepwater benthic 

communities that may not be easily detectable or clearly distinguishable from natural variation. 

Therefore, the impacts of routine activities would be expected to be negligible. Accidental events 

(below the threshold of a catastrophic spill, detailed in the Catastrophic Spill Event Analysis white 

paper [USDOI, BOEM, 2017]) do have the potential to cause detectable, severe damage to 

individual deepwater benthic communities. However, the number of such events is expected to be 

very small and is not expected to have population-level localized impacts and, therefore, might not 

be clearly distinguishable from natural variation. Therefore, the impacts of accidental events would 

be expected to be negligible to minor. Absent the expected information requirements and 

mitigation practices, the impacts resulting from the routine activities and accidental events of a 

proposed lease sale could be greater; the overall population-level impact level could range from 
4-142 Gulf of Mexico Multisale EIS

minor to major (in a theoretical, if improbable, worst-case scenario). However, those information 

requirements and mitigation practices are expected to continue.

Proposed OCS oil- and gas-related activities would also contribute incrementally, but only a 

negligible amount, to the overall OCS oil- and gas-related and non-OCS cumulative effects 

experienced by deepwater benthic communities. The previous and continuing OCS oil- and gasrelated cumulative impacts beyond the incremental contribution of a proposed action (a specific 

lease sale) are estimated to have negligible to minor impacts. Non-OCS oil- and gas-related 

activities such as commercial fishing (currently negligible) and shifting baseline environmental 

conditions related to climate change (currently negligible but likely to increase to major over time 

should current trends continue or worsen) could cause more noticeable impacts on deepwater 

benthic communities over the next 50 years.

4.4.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM would hold a lease sale excluding the available unleased blocks 

in the WPA and would offer all available unleased blocks in the CPA and a portion of the EPA. 

Alternative B would not fundamentally alter the conclusions reached for Alternative A, but it would 

reduce the potential impacts of a proposed lease sale to deepwater benthic communities in the 

WPA. The impacts from proposed activities to deepwater benthic communities would remain the 

same in leased portions of the CPA/EPA. Impacts resulting from accidental events should remain 

relatively localized, with the number of features affected being directly proportional to the size of the 

accident. An accident along the CPA/WPA border has the possibility to impact features in either

planning area. Although the area proposed for leasing in the WPA is relatively smaller than the 

proposed area of the CPA/EPA and would experience less projected OCS oil- and gas-related 

activity (refer to Chapter 3), deepwater benthic communities are found throughout all deep waters of 

the GOM (refer to Figure 4-10 through Figure 4-13 above) and, therefore, the impacts associated 

with Alternative B could still potentially cause some population-level effects.

At the regional, population-level scope of this analysis, the overall impact to deepwater

benthic communities as a result of the activities proposed in Alternative B are expected to be the 

same as Alternative A, i.e., negligible, assuming the continuation of expected mitigation practices. 

Absent these mitigations, the impacts resulting from the routine activities and accidental events of a 

proposed lease sale could be greater; the overall population-level impact could range from minor to 

moderate (in a theoretical, if improbable, worst-case scenario). This upper impact level is less than 

the potential major level impact that would be possible (absent mitigations) under Alternatives A and 

D. This difference is due to the greatly reduced area available for new leasing under Alternatives B 

and C, which would somewhat limit the number of potentially affected deepwater benthic 

communities and increase the likelihood of long-term recovery to pre-impact levels. However, it is 

believed that existing mitigation practices would continue to be applied to the proposed activities 

under Alternatives A-D, reducing the expected level of impacts from a proposed lease sale.
Description of the Affected Environment and Impact Analysis 4-143

Proposed OCS oil- and gas-related activities would also contribute incrementally, but only a 

negligible amount, to the overall OCS oil- and gas-related and non-OCS cumulative effects 

experienced by deepwater benthic communities. The previous and continuing OCS oil- and gasrelated cumulative impacts beyond the incremental contribution of a proposed action (a specific 

lease sale) are estimated to have negligible to minor impacts. Non-OCS oil- and gas-related 

activities such as commercial fishing (currently negligible) and shifting baseline environmental 

conditions related to climate change (currently negligible but likely to increase to major over time 

should current trends continue or worsen) could cause more noticeable impacts on deepwater 

benthic communities over the next 50 years.

4.4.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Under Alternative C, BOEM would hold a lease sale excluding the available unleased blocks 

in the CPA/EPA and would offer all available unleased blocks in the WPA. Alternative C would not 

fundamentally alter the conclusions reached for Alternative A, but it would reduce the potential 

impacts of a proposed lease sale in the available unleased block in the CPA/EPA. The impacts from 

the proposed activities to deepwater benthic communities would remain the same in leased portions 

of the WPA. Impacts resulting from accidental events should remain relatively localized, with the 

number of features affected being directly proportional to the size of the accident. An accident along 

the WPA/CPA border has the possibility to impact features in either planning area. Although the 

area proposed for leasing in the WPA is relatively smaller than the proposed area of the CPA/EPA 

and would experience less projected OCS oil- and gas-related activity (refer to Chapter 3), 

deepwater benthic communities are found throughout all deep waters of the GOM (refer to Figure 

4-10 through Figure 4-13 above) and, therefore, the impacts associated with Alternative C could 

still potentially cause some population-level effects.

At the regional, population-level scope of this analysis, the overall impact to deepwater

benthic communities as a result of the activities proposed under Alternative C are expected to be the 

same as Alternative A, i.e., negligible, assuming the continuation of expected mitigation practices. 

Absent these mitigations, the impacts as a result of the routine activities and accidental events of a 

proposed lease sale could be greater; the overall population level impact could range from minor to 

moderate (in a theoretical, if improbable, worst-case scenario). This upper impact level is less than 

the potential major level impact that would be possible (absent mitigations) under Alternatives A and 

D. This difference is due to the greatly reduced area available for new leasing under Alternatives B 

and C, which would somewhat limit the number of potentially affected deepwater benthic 

communities and increase the likelihood of long-term recovery to pre-impact levels. However, it is 

believed that existing mitigation practices would continue to be applied to the proposed activities 

under Alternatives A-D, reducing the expected level of impacts from a proposed lease sale.

Proposed OCS oil- and gas-related activities would also contribute incrementally, but only a 

negligible amount, to the overall OCS oil- and gas-related and non-OCS cumulative effects 

experienced by deepwater benthic communities. The previous and continuing OCS oil- and 
4-144 Gulf of Mexico Multisale EIS

gas-related cumulative impacts beyond the incremental contribution of a proposed action (a specific 

lease sale) are estimated to have negligible to minor impacts. Non-OCS oil- and gas-related 

activities such as commercial fishing (currently negligible) and shifting baseline environmental 

conditions related to climate change (currently negligible but likely to increase to major over time 

should current trends continue or worsen) could cause more noticeable impacts on deepwater 

benthic communities over the next 50 years.

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

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

Blocks South of Baldwin County, Alabama, Stipulations

The exclusion of any or all of the available unleased blocks subject to the either the 

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

Alabama, Stipulations (Alternative D) would not alter the above conclusions reached for Alternative 

A, B, or C. Under Alternative D, BOEM could hold a lease sale excluding the leasing of all blocks 

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

County, Alabama, Stipulations. This area exclusion would do relatively little to reduce the impacts 

as a result of the routine activities, accidental events, or cumulative impacts to deepwater benthic 

communities. Deepwater benthic communities are generally found in depths >300 m (984 ft), and 

the vast majority of lease blocks covered by these three stipulations are in shallower waters. NonOCS oil- and gas-related activities are also not expected to decrease under this alternative. At the 

regional, population-level scope of this analysis and assuming continuation of expected mitigation

practices, the overall impact to deepwater benthic communities as a result of the activities proposed 

under Alternative D are expected to be the same as Alternatives A-C, i.e., negligible. Absent the 

expected information requirements and mitigation practices, the impacts resulting from the routine 

activities and accidental events of a proposed lease sale could be greater; the overall populationlevel impacts could range from minor to major (in a theoretical, if improbable, worst-case scenario). 

However, those information requirements and mitigation practices are expected to continue.

Proposed OCS oil- and gas-related activities would also contribute incrementally, but only a 

negligible amount, to the overall OCS oil- and gas-related and non-OCS cumulative effects 

experienced by deepwater benthic communities. The previous and continuing OCS oil- and gasrelated cumulative impacts beyond the incremental contribution of a proposed action (a specific 

lease sale) are estimated to have negligible to minor impacts. Non-OCS oil- and gas-related 

activities such as commercial fishing (currently negligible) and shifting baseline environmental 

conditions related to climate change (currently negligible but likely to increase to major over time 

should current trends continue or worsen) could cause more noticeable impacts on deepwater 

benthic communities over the next 50 years.

4.4.2.9 Alternative E—No Action

Under Alternative E, a proposed lease sale would be cancelled. The potential for impacts 

would be none because new impacts to deepwater benthic communities related to a cancelled lease 

sale would be avoided entirely.
Description of the Affected Environment and Impact Analysis 4-145

The Sargassum cycle is 

expansive, encompassing 

most of the western Atlantic 

Ocean and the Gulf of Mexico.

Continuing impacts to the communities would be limited to existing routine activities, 

accidental events, and cumulative impacts associated with previous OCS lease sales. BOEM’s 

current mitigation practices already regulate these activities and should continue to limit associated 

impacts to the negligible to minor range for OCS oil- and gas-related cumulative impacts. Ongoing 

non-OCS oil- and gas-related activities are negligible at present time, but they could potentially 

become greater, even rising to major, should there be future changes in fishing practices or worstcase changes in climate change-related environmental conditions.

4.5 SARGASSUM AND ASSOCIATED COMMUNITIES

Sargassum is a genus of large brown seaweed (a type 

of algae) that floats in island-like masses (USDOC, NOAA, 

Office of Ocean Exploration and Research, 2014). In the Gulf of 

Mexico, Sargassum and the organisms that reside within or 

around the matrix of plants are some of the most widely 

distributed and easily recognizable species in the GOM. 

Sargassum, as pelagic algae, is a widely distributed resource that is ubiquitous throughout the 

northern GOM and northwest Atlantic, and it is part of a cycle that spans most of the Northern 

Hemisphere of the Atlantic Ocean including the Caribbean Sea. As such, Sargassum might be 

potentially vulnerable to OCS oil- and gas-related activities. The analysis is focused on the potential 

impact-producing factors from OCS oil- and gas-related routine activities (i.e., exploration, 

development, and production), accidental events, and cumulative impacts. The potential magnitude 

of impact for each of these impact-producing factors is provided in Table 4-12 to help the reader 

quickly identify the level of potential impacts for Sargassum and its associated communities. The 

impact level definitions and the analyses supporting these conclusions are then discussed in detail in 

this section. The description of the affected environment provides a baseline that encompasses all 

previous and ongoing OCS oil- and gas-related and non-OCS oil- and gas-related activities.

Table 4-12. Sargassum and Associated Communities Impact-Producing Factors That Are Reasonably 

Foreseeable.

Sargassum and 

Associated Communities Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Vessel Operations Negligible Negligible Negligible Negligible None

Drilling Operations Negligible Negligible Negligible Negligible None

Accidental Impacts

Drilling Operations Negligible Negligible Negligible Negligible None

Vessel Operations Negligible Negligible Negligible Negligible None

Oil Spill and Cleanup Negligible Negligible Negligible Negligible None
4-146 Gulf of Mexico Multisale EIS

Cumulative Impacts

Incremental 

Contribution2 Negligible Negligible Negligible Negligible None

OCS Oil and Gas3 Minor to

Moderate

Non-OCS Oil and Gas4 Negligible

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

Within this chapter, characteristics unique to Sargassum are discussed along with life 

history. In addition, the roles of Sargassum functioning as a habitat, the species that depend on 

Sargassum, and factors that influence Sargassum are also discussed. During this analysis, the 

following potential impact-producing factors were screened for their potential to impact Sargassum: 

• vessel operations (Chapter 3.1.4.3);

• presence of toxins in water column (Chapters 3.1.5.1 and 3.1.5.2);

• sediment deposition on seafloor (Chapters 3.1.3.3.2 and 3.1.3.3.3);

• sediment deposition into water column (Chapter 3.1.3.3.3);

• alteration of water-flow patterns;

• impingement (Chapter 3.1.5.1.6);

• vessels sinking (Chapter 3.2.5);

• marine debris (Chapter 3.2.7);

• oil spills (Chapter 3.2.1);

• oil-spill cleanup (Chapter 3.2.8); and

• chemical and drilling-fluid spills (Chapter 3.2.6).

An in-depth analysis of these potential factors determined that, although many may occur 

within the GOM, few occur at an extent that could cause impacts to the population of Sargassum as 

a whole. This includes sediment deposition on the seafloor or in the water column, vessels sinking, 

impingement, marine debris, and alteration of water flow patterns. Additionally, impacts associated 

with the presence of toxins and sediments in the water column from discharges during routine 

operations are managed through the NPDES permitting process or by the MARPOL Annex V Treaty. 

Regulation and enforcement of these laws is conducted by a number of agencies, such as the U.S. 
Description of the Affected Environment and Impact Analysis 4-147

Environmental Protection Agency, NOAA, and the U.S. Coast Guard. These regulations were put in 

place to protect water quality so that it is maintained at a level that is nontoxic to the organisms in 

the water where it is being discharged and are not addressed in this chapter for Sargassum, but 

rather are discussed in Chapter 4.2 (Water Quality). Additionally, cooling water discharges from 

vessels are also not addressed because, compared with the surface area of the environment, the 

area that could be impacted by vessel discharges is miniscule. Finally, the spatial extent and the 

transient nature of the Sargassum cycle is such that it would take a low-probability catastrophic

event to affect enough Sargassum to result in population-level impacts across the GOM for more 

than a season, which is not reasonably foreseeable as a result of a proposed lease sale. Other 

factors like deposition of sediments onto the seafloor do not occur within the same section of the 

water column where Sargassum occurs. As such, only the following impact-producing factors were 

identified as having the potential to impact Sargassum and were carried forward to a full analysis:

• vessel operations (Chapter 3.1.4.3; routine and accidental, including 

discharges);

• chemical and drilling-fluid spills (Chapter 3.2.6; accidental only);

• oil spills (Chapter 3.2.1; accidental only); and

• oil-spill cleanup (Chapter 3.2.8; accidental only).

To facilitate a discussion on the spatial extent of the Sargassum cycle and to put the impactproducing factors in context, Figure 4-14 depicts how these plants move around the Northern 

Hemisphere. The Sargassum loop system initiates in the Sargasso Sea. Atmospheric conditions 

create wind patterns that push Sargassum south, into the Caribbean Sea where it is pushed west by 

the oceanic and atmospheric currents carrying it into the Gulf of Mexico. There it washes ashore on 

the Gulf Coast or gets swept out the Florida Strait via the Gulf Stream (Gower et al., 2013; Frazier 

et al., 2015). Figure 4-14 represents the spatial extent of Sargassum, demonstrating that there is a 

high degree of connection among the Gulf of Mexico OCS planning areas and other oceanic basins 

and large-scale oceanic features (e.g., Gulf Stream).
4-148 Gulf of Mexico Multisale EIS

Figure 4-14. Sargassum Loop System (adapted from Gower et al., 2013, and Frazier et al., 2015).

Impact-Level Definitions

For this analysis, the following criteria were used to categorize the effects of impactproducing factors to Sargassum and associated communities:

• Negligible – Impacts are undetectable or limited in scale to the immediate area 

of the impact-producing factor. This may include mortality of the plants or 

animals associated with Sargassum. Such impacts may result in changes to a 

local community’s species abundance and composition, community structure, 

and/or ecological functioning, but any such changes would be spatially localized, 

short term in duration, and would not alter the overall status of Sargassum or 

associated communities in the GOM.

• Minor – Impacts are detectable and result in changes beyond the immediate 

area of the impact-producing factor. Such impacts could result in noticeable 

changes to a local community’s species abundance and composition, community 

structure, and/or ecological functioning, but would be spatially localized, short 
Description of the Affected Environment and Impact Analysis 4-149

term in duration, and would not alter the overall status of Sargassum or 

associated communities in the GOM.

• Moderate – Impacts cause substantial, population-level changes in species 

composition, community structure, and/or ecological functioning beyond the 

immediate area of the impact-producing factor. These impacts would be 

expected to be spatially extensive and may impact communities that rely on 

Sargassum for transportation of larvae, settlement, or food beyond the area of 

the impact-producing factor. However, impacts to Sargassum and associated 

communities are expected to be temporary, and there would be no disruption of 

the global Sargassum cycle.

• Major – Impacts result in the loss of Sargassum over large sections of the GOM. 

This would result in substantial, population-level changes in species composition, 

community structure, and/or ecological functioning for Sargassum and 

communities that rely on Sargassum for transportation of larvae, settlement, or 

food beyond the area of the impact-producing factor. These impacts would be 

expected to be spatially extensive and possibly disrupt the global Sargassum

cycle.

4.5.1 Description of the Affected Environment

Plant Characteristics

The pelagic complex in the 

GOM is comprised of Sargassum

natans and Sargassum fluitans (Lee 

and Moser, 1998; Stoner, 1983; 

Littler and Littler, 2000). Both 

species of macrophytes live 

immediately below the water surface 

and are fully adapted to a pelagic 

existence (Lee and Moser, 1998). As 

can be seen in Figure 4-15, 

Sargassum is characterized by a 

brushy, highly branched thallus with 

numerous leaf-like blades and 

berrylike pneumatocysts (CostonClements et al., 1991; Lee and Moser, 1998; Littler and Littler, 2000). These air bladders contain 

mostly oxygen and can facilitate buoyancy (Hurka, 1971). Net production in Sargassum also 

exceeds respiration by 1.3 times (Blake and Johnson, 1976), and the population can double in size 

every 3 months (Lapointe, 1986), suggesting that Sargassum may be important in the global carbon 

cycle. Sargassum plants may be up to a few meters in length and may be found floating alone or in 

larger rafts or mats depending on the environmental and physiochemical factors. Reproduction 

Figure 4-15. Pelagic Brown Algae in the Genus Sargassum

(image courtesy of H. Scott Meister, South 

Carolina Department of Natural Resources) 

(USDOC, NOAA, 2014b).
4-150 Gulf of Mexico Multisale EIS

typically occurs through fragmentation, and the size, shape, and distribution of Sargassum mats can 

change rapidly depending on currents, wind, and other factors.

Life History

The life history of Sargassum in the GOM is part of a larger cycle that includes the midAtlantic Ocean and the Caribbean Sea (Frazier et al., 2015). This cycle begins in the Sargasso Sea 

where Sargassum remains year round. However, winds and currents move some of this Sargassum

south into the Caribbean Sea and eventually into the GOM via the Yucatan Channel. Once in the 

GOM, it moves into the western area where it uses nutrient inputs from coastal rivers, including the 

Mississippi River, for growth. As Sargassum abundance increases, plants would continue to travel 

east during the summer months; however, a large quantity of plants would travel in to the nearshore 

where they would be deposited on coastal beaches. Sargassum deposition on Gulf Coast beaches 

is important because Sargassum facilitates dune stabilization and provides a pathway for nutrient 

and energy transfer from the marine environment to the terrestrial environment (Webster and Linton, 

2013). Eventually the plants moving east would be incorporated into the Gulf Stream where they 

return to the Sargasso Sea (Figure 4-14). Throughout this cycle, plants would continue to grow, 

reproduce, and die. When a plant dies, it can sink to the seafloor, transporting nutrients and 

resources to the seafloor (Coston-Clements et al., 1991; Parr, 1939; Wei et al., 2012). Although the 

cycle continues year round, the rapid growth of Sargassum populations in the western GOM typically 

occurs during spring/summer (Gower et al., 2006; Gower and King, 2008; Gower and King, 2011). 

Estimates suggest that between 0.6 and 6 million metric tons of Sargassum are present annually in 

the GOM, with an additional 100 million metric tons exported to the Atlantic basin (Gower and King, 

2008; Gower and King, 2011, Gower et al., 2013). The spatial expanse of this life history facilitates 

the rapid recovery from episodic environmental perturbations because of the remote probability that 

any single event could impact the entire spatial distribution.

Habitat Function

While in the oligotrophic waters of the 

GOM, Sargassum provides islands of high energy 

and carbon content in an otherwise nutrient and 

carbon poor environment (Stoner, 1983). As can 

be seen in Figure 4-16, Sargassum mats, 

comprised of a single or multiple plants in a matrix, 

support a diverse assemblage of marine 

organisms, including micro- and macro-epiphytes 

(Carpenter and Cox, 1974; Coston-Clements 

et al., 1991), fungi (Winge, 1923), more than 

100 species of invertebrates (Coston-Clements 

et al., 1991; Huffard et al., 2014), over 100 species 

of fish (Dooley, 1972; Stoner, 1983; Huffard et al., 

2014), four species of sea turtles (Carr, 1987a;

Manzella et al., 2001), and various marine birds

Figure 4-16. Small Fishes in Sargassum

(USDOC, NOAA, Office of Ocean 

Exploration and Research, 2010).
Description of the Affected Environment and Impact Analysis 4-151

(Lee and Moser, 1998). Sargassum serves as nurseries, sanctuaries, and forage grounds for both 

commercially and recreationally exploited species (Adams, 1960; Bortone et al., 1977; Dooley, 1972; 

Wells and Rooker, 2004). Sargassum has also been identified as a critical habitat for the 

loggerhead sea turtle (Caretta caretta) (Federal Register, 2014a). Community composition of 

Sargassum mats vary spatiotemporally depending on the environmental and physiochemical factors 

of the waters where the Sargassum mats reside, resulting in a high degree of biologic diversity in 

species abundance, composition, and life history (Wells and Rooker, 2004).

Sargassum-Dependent Communities

Invertebrates

Epiphytic cyanobacteria contribute to overall production and nutrient recycling within the 

Sargassum complex (Wells and Rooker, 2004). Sargassum is colonized by bacteria, hydroids, and 

bryozoans, providing the base of a food web (Dooley, 1972). Both sessile and motile invertebrates 

are found within the Sargassum community. Epifaunal organisms include colonial hydroids, 

encrusting bryozoans, the polychaete Spirorbis, barnacles, sea spiders, and the tunicate Diplosoma 

(Dooley, 1972; Coston-Clements et al., 1991; Huffard et al., 2014). Older plants can become heavily 

encrusted with these organisms, causing them to sink to the seafloor. Some of the motile fauna 

found within the Sargassum matrix include polychaetes, flatworms, nudibranchs, decapod 

crustaceans, and various molluscs (Parr, 1939; Coston-Clements et al., 1991). Sargassum matrices 

provide a habitat that affords a degree of protection, entrains food, and is an effective method for 

traversing long distances for Sargassum-dependent and Sargassum and associated organisms.

Sea Turtles

Four of the five species of sea turtles found in the GOM (all are listed under the ESA) are 

associated with floating Sargassum (Carr and Meylan, 1980; Carr, 1987a; Coston-Clements et al., 

1991; Schwartz, 1988; Witherington et al., 2012). The hatchlings of loggerhead, green (Chelonia 

mydas), Kemp’s ridley (Lepidochelys kempii), and hawksbill (Eretmochelys imbricata) sea turtles are 

thought to find the Sargassum rafts when actively seeking frontal zones, then utilizing the habitat as 

foraging grounds and protection during their pelagic “lost years” (juvenile years in which turtle 

sightings are scarce) (Carr, 1987a; Coston-Clements et al., 1991; Witherington et al., 2012; Putman 

and Mansfield, 2015). In 2014, NOAA designated critical habitat for the Northwest Atlantic Ocean 

Distinct Population Segment for loggerhead sea turtles in waters including associated Sargassum

habitat and beach habitat of the GOM and along the U.S. Atlantic Coast (Federal Register, 2014a). 

For additional information on sea turtles, refer to Chapter 4.9.2 (Protected Species).

Birds

The presence of Sargassum can also influence local abundance and occurrence of certain 

species of marine birds by concentrating food, as many birds actively feed on or around the mats 

(Lee and Moser, 1998; Moser and Lee, 2012). Birds with over 25 percent of their prey living in 

Sargassum are classified as Sargassum specialists. Specialist species included several species of 

shearwaters, terns, phalaropes, petrels, and gulls (Moser and Lee, 2012). For the birds that rely on 
4-152 Gulf of Mexico Multisale EIS

Sargassum for food or rest, the importance of the Sargassum and associated communities to 

seabird abundance and seasonal distribution is expected to be high (Moser and Lee, 2012). For 

additional information on birds, refer to Chapter 4.8. 

Fish

The assemblages of fishes using Sargassum as a habitat are highly variable in time and 

space (Huffard et al., 2014). Jacks, pompanos, mackerels, scads, triggerfishes, filefishes, 

seahorses, pipefishes, and frogfishes represent up to 97 percent of the fishes in Sargassum mats 

(Dooley, 1972; Bortone et al., 1977). Some species that are endemic to Sargassum utilize the 

habitat for early life stages as well as adult stages, while other species may rely on the habitat only 

as a source of food, protection, and a method of passive transportation during early life stages 

(Bortone et al., 1977; Wells and Rooker, 2004). The abundance of juvenile fish associated with 

these mats suggests that they serve as an important nursery habitat for numerous species (Dooley, 

1972). By serving as a nursery habitat for pelagic, benthic, and even estuarine species, Sargassum

may have influence on the recruitment success of the fishes using it as habitat. For additional 

information on fish, refer to Chapter 4.7. 

4.5.2 Environmental Consequences

Because of the spatial extent of the Sargassum cycle, the community dynamics of 

Sargassum and Sargassum-dependent species are influenced by a myriad of complicated factors. 

Many of these factors are poorly understood due to the size and scope of the Sargassum cycle. For 

example, without any substantial changes in environmental conditions, the biomass of Sargassum 

was 200-fold greater in 2011 than the previous 8-year average (Gower and King, 2011). The event 

had its origin north of the mouth of the Amazon (Gower et al., 2013). The resulting large quantities 

of Sargassum washing up on beaches became a nuisance for recreation. Additionally, comparisons 

across a 40-year period documented that there was a change in community composition for the 

Sargassum-dependent species found in the Atlantic Ocean (and presumably a pre-cursor to GOM 

populations). However, no specific anthropogenic or environmental factor could be identified as the 

source of change (Huffard et al., 2014). Conversely, one factor that may negatively influence 

Sargassum communities is that the oceanographic processes that concentrate Sargassum into mats 

and rafts may also concentrate surface pollutants and marine debris (Burns and Teal, 1973; Laffoley 

et al., 2011; Powers et al., 2013). This was evident during the Deepwater Horizon explosion, oil 

spill, and response as many Sargassum mats were found immersed in oil with little or no visible 

living associated organisms (Powers et al., 2013). Additionally, Sargassum may be influenced by 

many nonpoint sources of pollution as pollutants are concentrated, possibly magnifying the 

environmental impacts of those substances (Laffoley et al., 2011).

Of major importance is that these communities play an important role to ESA-listed species 

by providing food, habitat, and a method of transportation. BOEM consults on these species with

the FWS and NMFS. These species include sea turtles and birds; to read about the protected 

species that use these habitats, refer to Chapters 4.9.2 and 4.9.4, respectively.
Description of the Affected Environment and Impact Analysis 4-153

4.5.2.1 Routine Activities

Impact-producing factors associated with routine activities for a proposed action that could 

affect Sargassum are limited to impacts from vessel operations and impingement on oil and gas 

structures. However, the impediment of the movement of Sargassum mats is expected to affect 

such a small quantity of algae that impacts would be negligible with no consequences to the overall

Sargassum community.

Vessel Operations

It is expected that a fleet of vessels would be used to support oil and gas exploration, 

production, and possibly other OCS oil- and gas-related operations across the GOM (Chapter 

3.1.4.3). Because of the pelagic life history of Sargassum, vessels supporting oil and gas operations 

would routinely come in contact with Sargassum and associated communities. When impacts occur, 

it would be the result of oil or fuel spills (discussed in the “Accidental Events” chapter below) or 

Sargassum coming in contact with the vessel hull or in contact with the propulsion system. The 

consequence could be the break-up of Sargassum plants into smaller pieces, death of Sargassum 

plants, or dislodging and/or death of epiphytic organisms or organisms living in close proximity to 

Sargassum. However, impacts to Sargassum would only occur if the vessel is traveling at a high 

rate of speed and comes in contact with the plants. If individual plants are broken into moderately 

sized pieces during low-speed travel, it is expected that the plants would continue to grow as 

multiple separate entities through vegetative propagation. For Sargassum-dependent organisms 

that are physically attached to the plant matrix (e.g., epiphytes), dislodgement would result in death 

as they sink to the seafloor or are preyed upon. For animals that live in close proximity to 

Sargassum, it is expected that dislodgement would be temporary as they would find their way back 

to the plant, or other plants, after the vessel had passed. Again, this would only occur if contact 

occurs with the vessel traveling at a rate of speed great enough to actually dislodge organisms. This 

critical speed would be dependent on sea-state, types of organisms present, vessel size, and depth 

of Sargassum in the water column.

Regardless of the possibility of impacts to individual Sargassum plants and associated 

communities, vessel operations are expected to have negligible impacts on the population of 

Sargassum or to the animals that colonize the plants. The primary reason is that the Sargassum 

cycle rapidly replaces (in days to weeks) any plants that are damaged or destroyed by OCS oil- and 

gas-related vessels in a given area. Vessels and Sargassum each move haphazardly, minimizing 

the possibility of contact to any particular piece of Sargassum. If contact does occur, there are few 

locations on the vessel (e.g., rudders, intakes) where Sargassum could actually become impinged. 

Additionally, the oceanographic processes that cause Sargassum to form large rafts would also 

cause large pieces of marine debris (e.g., trees, lumber, and trash) to collect with the Sargassum. 

As such, many vessels would avoid large rafts or slow down as they pass through, minimizing 

potential impacts to Sargassum. Finally, many of the vessels working in the OCS oil- and gasrelated fields rely on displacement hulls rather than planing hulls. Because of this, most vessels 

would push plants away from the vessel rather than colliding with the plants. Damage would be 

limited to those that pass through the propulsion system of the vessel. Even on the largest vessels, 
4-154 Gulf of Mexico Multisale EIS

the diameter of the propellers is relatively small, resulting in short-term, localized damage that 

should have negligible impacts to the population of Sargassum or the organisms that coexist within 

the plant matrix.

4.5.2.2 Accidental Events

Impact-producing factors associated with accidental events for a proposed action include 

(1) impacts associated with drilling operations, (2) impacts due to vessel operations, and (3) impacts 

resulting from an oil spill and associated cleanup operations. These impact-producing factors would 

have varied effects depending on the intensity of the spill, the presence of Sargassum, and the 

abundance of Sargassum in the vicinity of the spill.

Drilling Operations

Accidental events associated with drilling operations are limited to the accidental discharge 

of oil (discussed separately below), drilling muds, and chemicals into the water column (Chapter 

3.2.6). This type of event may occur if the equipment separating SBFs from the cuttings 

malfunctions. Although the toxicity of SBFs is regulated by the USEPA and are not typically toxic 

(USEPA, 2004, 2007, and 2009b), an unexpected release into a Sargassum raft could potentially 

result in damage to the plants or the organisms that inhabit Sargassum. Because of the high cost of 

SBFs, the systems responsible for separating SBFs from the drill cuttings for reuse are monitored 

closely; as such, accidental discharges of SBFs would tend to be limited in size and scope. Once in 

the water column, SBFs would clump and sink quickly and impact only the plants and animals that 

come in contact with the SBFs. Because Sargassum is constantly moving horizontally within the 

environment, the abundance of plants that could be impacted by any given accident would be 

minimal. Due to the cyclical life history of Sargassum, dead plants would sink to the seafloor and 

would rapidly be replaced by new plants moving into the area. Although impacts could occur at 

isolated locations and at a small scale, they would be limited in size, scope, and duration, with 

negligible population-level impacts expected.

Vessel Operations

Although regulated by MARPOL and other regulations, one type of accidental event 

associated with vessel operations that may impact Sargassum is the release of floating debris into 

the surface waters of the GOM (Chapters 3.1.5.2 and 3.2.7). Another is spills caused by vessel 

collisions. The accidental release of marine debris could occur when cargo is not properly restrained 

on deck while underway or during transfer operations between vessels and platforms. Losses of 

large quantities of debris are rare; however, losses of smaller pieces of debris might happen (e.g., 

trash, safety vests, hardhats, etc.). Floating debris is subject to the same oceanographic process 

that influences and moves Sargassum, resulting in marine debris and Sargassum rafting together. 

Marine debris may have little impact on the plants, but the organisms living in close proximity might 

be impacted. This includes the ingestion of plastics by sea turtles, ingestion of microplastics by 

fishes and invertebrates, or the release of toxins from within an object (e.g., a bucket of paint) or as 

an object undergoes degradation (Engler, 2012; Schuyler et al., 2012; Wright et al., 2013). Given 
Description of the Affected Environment and Impact Analysis 4-155

the lack of stationary gyres in the GOM, OCS oil- and gas-related floating debris would not be 

expected to remain long enough to undergo substantial degradation before washing ashore along a 

beach or sinking to the seafloor. There is a remote possibility that some debris might be advected 

within the Gulf Stream and carried to the gyre in the mid-Atlantic. This debris could remain long 

enough to undergo degradation or be ingested; however, this would be a small enough amount of 

debris from OCS oil- and gas- related activities to have a negligible impact. BOEM and BSEE have 

addressed the marine debris issue by historically imposing marine debris awareness and prevention 

on the oil and gas industry through NTL 2015-BSEE-G03 as a part of the Protected Species 

Stipulation. Overall, vessel operations are expected to have a negligible impact on Sargassum and 

their associated communities because of the minimal volume expected and short residency times.

Oil Spills and Associated Cleanup Operations

Oil spills are the major accidental events of concern to the Sargassum community (refer to 

Chapter 3.2.1 for information on oil spills). The risk of various sizes of oil spills occurring as a result 

of a proposed lease sale is presented in Table 3-17. 

All known reserves in the GOM have specific gravity characteristics that indicate the oil 

would float to the sea surface (Chapter 3.2.1.2). Oil on the sea surface has the potential to 

negatively impact Sargassum communities. Some components of oil on the sea surface would be 

removed through evaporation, dissipation, biodegradation, and oil-spill cleanup operations; however, 

depending on the size of the spill, some of them could persist, contacting Sargassum communities 

(Chapters 3.2.1.3 and 3.2.8). Oil at the sea surface can be mixed into the upper water column by 

wind and wave action to a depth of approximately 33 ft (10 m) (Lange, 1985; McAuliffe et al., 1975 

and 1981b; Knap et al., 1985). With vigorous wave action, the oil can form an emulsion with water 

that is viscous and persistent. Oil treated with dispersant on the sea surface would mix with the 

water where its contact with Sargassum may be temporarily increased in the upper few meters of the 

water column (McAuliffe et al., 1981a). As time passes, the oil would begin to adhere to particles in 

the water column, form clumps, and sink toward the seafloor (International Tanker Owners Pollution 

Federation Limited, 2002; Kingston et al., 1995; Powers et al., 2013).

The impacts of oil contact with Sargassum communities would vary depending on the 

severity of exposure. Sargassum that contacts concentrated oil that coats the algae and attached 

organisms would likely die and sink to the seafloor (Powers et al., 2013). Motile organisms that are 

dependent on the algae for habitat (e.g., shrimp, crabs, nudibranchs, snails, Sargassum fish, etc.) 

may also be directly contacted by the oil, resulting in death, or may be displaced into open water. 

Sargassum exposed to oil in lower concentrations may suffer sublethal impacts and concentrate 

hydrocarbons, toxins, and chemicals (Burns and Teal, 1973). Exposure to these low-level toxins 

could result in the loss of associated organisms that use the algae as a substrate and other 

organisms that use the matrix as habitat due to the presence of bacterial-mediated hypoxic 

conditions in the immediate vicinity of the plant as the oil is consumed (Powers et al., 2013). 

However, hypoxia would be naturally mitigated due to wave action. Pelagic organisms feeding on or 

around the community may suffer sublethal effects that could reduce health and reproduction 
4-156 Gulf of Mexico Multisale EIS

through reduced growth or fecundity. For information on fauna that can be part of the Sargassum

community, refer to Chapters 4.7 (Fish and Invertebrate Resources), 4.8 (Birds), 4.9.2 (Sea 

Turtles), and 4.9.4 (Protected Birds).

Spill-response activities may contribute to negative impacts on Sargassum (refer to Chapter 

3.2.8 for information on oil-spill response activities). The number of vessels concentrated in a given 

area to clean up a spill can increase physical damage to the Sargassum community, especially in 

the immediate vicinity of the spill. Response activities, such as skimming oil from the sea surface or 

burning oil at the surface, can damage and remove Sargassum that may not have contacted oil. 

However, for oil-coated Sargassum, these impacts may be inconsequential, as a large part of the 

Sargassum affected would not be expected to survive (Powers et al., 2013). Another major 

response activity that may occur is the spraying of dispersant. Direct effects of dispersant on many 

of the more mobile constituents of the Sargassum community are limited, but dispersants are toxic to

Sargassum plants and many invertebrates (Powers et al., 2013; Almeda et al., 2014). The use of 

dispersants is a trade-off to achieve the least overall environmental damage. For example, 

dispersants may increase short-term contact of oil with Sargassum and may have some inherent 

toxic properties, but their use can promote diffusion of oil, resulting in biodegradation, clumping, and 

sinking.

A spill may impact the survivability and productivity of Sargassum in an area (Powers et al., 

2013). However, an accidental spill would only be expected to have an impact in the immediate 

area and would be short in duration. Given the life history of Sargassum, it is expected that, for an 

accidental spill, fresh plants would replace the old plant within days to weeks. The new plants would 

also provide habitat for any organisms with the desire to leave impacted plants, which could happen 

in the natural life cycle of Sargassum. The Sargassum community is widely distributed over a very 

large area, including two oceans, and appears to have an annual cycle of growth that lends itself to 

resilient recovery in a short time. Due to the spatial extent of the Sargassum cycle, impacts due to 

an accidental oil spill (large or small) are expected to be negligible to the Sargassum population; 

however, in the immediate area of a spill, the localized and short-term impacts could range from 

moderate to major depending directly on the size of the spill and amount of Sargassum in the area.

4.5.2.3 Cumulative Impacts

Several impact-producing factors can affect Sargassum, including vessel-related operations, 

oil and gas drilling discharges, operational discharges, accidental spills, non-OCS oil- and gasrelated vessel activity, and coastal water quality. 

Cumulative OCS Oil and Gas Program

Vessels transiting the GOM pass through Sargassum mats and may produce slight impacts 

to the Sargassum community, such as some propeller-related impacts, and possible impingement 

impacts (refer to Chapter 3.3.1.7 for information on cumulative service-vessel numbers). None of 

these would have more than minor localized impacts to the mats, but they could lead to the loss of 

plants or stress for organisms, albeit haphazardly due to the variability in vessel traffic and 
Description of the Affected Environment and Impact Analysis 4-157

Sargassum movement patterns. The OCS oil- and gas-related structures can impede the movement 

of Sargassum mats and may entrap small quantities of the algae. Combined, these impacts are 

expected to remain negligible with no consequences to the overall Sargassum community either 

spatially or temporally.

The OCS oil- and gas-related drilling results in discharges of drill cuttings with small 

quantities of associated drilling muds and well treatment chemicals. Most cuttings from well drilling 

are discharged from the drill platform at the sea surface where they disperse (CSA, 2006; Kennicutt 

et al., 1996; NRC, 1983). Floating mats of Sargassum that pass by a drilling operation would 

experience short-term exposure to drill cuttings with associated muds and well treatment chemicals. 

Discharges are regulated by USEPA to require that discharges released into the environment are 

nontoxic or not concentrated enough to become toxic (USEPA, 2004, 2007, and 2009b). Drilling 

operations create an area of high turbidity in the vicinity of cuttings discharges. Impacts from 

sedimentation to the community organisms may include “changes in respiration rate, abrasion and 

puncturing of structures, reduced feeding, reduced water filtration rates, smothering, delayed or 

reduced hatching of eggs, reduced larval growth or development, abnormal larval development, or 

reduced response to physical stimulus” (Anchor Environmental CA, L.P., 2003). Combined with 

other impacts, the results would still remain negligible given the haphazard nature of Sargassum 

movements.

The OCS oil- and gas-related platforms and drill ships produce similar effects with 

operational discharges. Larger vessels and offshore platforms discharge effluents from sanitary 

facilities (gray water) and circulate seawater to cool ships’ engines, electric generators, and other 

machines. The cooling water discharge may be up to 20 °F (11 °C) warmer than the surrounding 

seawater (USDHS, CG and USDOT, MARAD, 2003; Patrick et al., 1993). This temperature 

difference can accumulate in the vicinity of the discharge. For OCS oil- and gas-related stationary 

platforms and drill ships, localized warming of the water could occur (Emery et al., 1997; USDHS, 

CG, and USDOT, MARAD, 2003). However, the warm water is rapidly diluted, mixing to background 

temperature levels within 328 ft (100 m) of the source (USDHS, CG and USDOT, MARAD, 2003). 

Additionally, produced waters from stationary locations are rapidly diluted, and impacts are only 

observed within 328 ft (100 m) of the discharge point (Neff and Sauer, 1991; Trefry et al., 1995; 

Gittings et al., 1992b). Those effects are localized, with only brief contact to passing Sargassum

before dilution to background levels; however, this could result in discomfort, displacement, or death 

to some of the more sensitive organisms. These effects would comprise a negligible portion of the 

overall cumulative impact to Sargassum communities.

Accidental spills of oil and other chemicals could affect Sargassum and its community 

wherever they contact the algae. Small spills would have a limited local effect on a small portion of 

the Sargassum community. Short-term exposure of Sargassum to high concentrations of oil and 

chemicals could result in death and sinking of the algae and organisms contacted. The size of the 

overall impact on Sargassum and associated communities would depend on the size of the spill and 

the success of spill-response efforts; substantial impacts could be expected to the organisms 

exposed. This includes death if oil concentrations in the water column are great enough to result in 
4-158 Gulf of Mexico Multisale EIS

ingestion of oil or coating of the organisms residing in the vicinity of Sargassum mats (Fucik et al., 

1995; Brewton et al., 2013).

Cumulative impacts of the OCS Oil and Gas Program include past actions such as the 

Deepwater Horizon oil spill. Studies of the impact of the spill on Sargassum have shown that the 

spilled oil affected 23 percent of the Sargassum in the northern Gulf of Mexico with heavy oil. In 

addition to the 873-1,749 km2 (337-675 mi2

) of area in which Sargassum was contacted by oil, total 

loss to the population was estimated to include an additional 4,524-9,392 km2 (1,747-3,626 mi2

) of 

foregone area from lost growth (Deepwater Horizon Natural Resource Damage Assessment 

Trustees, 2016). This represents a major impact to the Sargassum of the Gulf of Mexico. Due to 

the high growth rate, which is estimated to be approximately 4 percent per day, recovery would be 

swift. Powers et al. (2013), using aerial surveys in 2010, 2011, and 2012, documented a four-fold 

increase in Sargassum abundance above that observed in 2010 during and shortly after the spill. 

Therefore, due to the extensive nature of the impact and the resilient nature of the Sargassum

population, the cumulative impacts to Sargassum are estimated to be minor to moderate. 

Non-OCS Oil- and Gas-Related Impacts

Marine vessels of all types produce at least some minor effects to the environment (refer to 

Chapter 3.3.2.2). Increased abundance of non-OCS oil- and gas-related vessels operating in the 

same environment as Sargassum presents an increase in the expected vessel-related damage to 

Sargassum and associated communities. Given that most vessels are limited to the waters 

nearshore (e.g., recreational fishermen), the impacts on Sargassum are expected to be minor. 

Sargassum found in near-coastal waters is expected to eventually senesce (the process of aging in 

plants) and sink to the seafloor or be deposited on coastal beaches. As such, additional damage to 

any Sargassum that may occur would not impact the population. Offshore traffic would be limited 

and occur in a haphazard manner beyond shipping lanes. As such, the movement of Sargassum, 

combined with the movement of vessels, reduces the potential for impacts to any given Sargassum, 

resulting in negligible cumulative impacts by non-OCS oil- and gas-related vessel traffic.

Declining coastal water conditions in the Gulf of Mexico, due to eutrophication, are a nonOCS oil- and gas-related impact that could result in landscape level impacts to Sargassum (Chapter 

3.3.2.11). Increased nutrient loading can lead to increased turbidity from plankton growth (e.g., in 

the summer; refer to Chapter 3.3.2.12). Turbidity could result in a decrease in Sargassum 

production and result in stress to the organisms utilizing these habitats, while increased nutrients 

could result in an increased growth of Sargassum. A reduction in production could result in a 

decrease in the ability of Sargassum to sequester nutrients and carbon dioxide and to produce 

oxygen, while an increase in production could provide more habitat. The exact impact of declining 

water quality is unknown because Sargassum can pass in and out of these waters depending on the 

prevailing conditions, and much of the more hypoxic and highly turbid waters occur nearshore where 

Sargassum would not normally survive because it would be deposited on a coastal beach or 

senesce (the process of aging in plants) and sink to the seafloor.
Description of the Affected Environment and Impact Analysis 4-159

Impacts associated with possible climate change impacts remain unknown for a habitat with 

such a wide-ranging distribution. Increased temperatures could result in benefits to Sargassum by 

increasing the range where the plants could be found and by increasing growth rates. This could 

result in beneficial impacts like increased sequestration of nutrients and more potential habitat for 

colonization and increased larval survival. However, it is possible that growth rates could increase to 

a point where the fouling of beaches and shipping lanes in the GOM and the Atlantic Ocean could 

become problematic, resulting in moderate to major impacts to coastal communities. Additionally, 

stratification of the water column and changes in current patterns due to a changing climate could 

alter access to nutrients and move Sargassum into areas not previously observed. Finally, 

organisms that colonize Sargassum could be impacted as pH levels fluctuate, resulting in negative 

impacts. Combined, this would result in impacts ranging from beneficial to major and would be 

expected to vary by location, given the distribution of Sargassum. As such, impacts of climate 

change to Sargassum are not easily estimated.

Combined, the cumulative impacts of OCS oil- and gas-related operations would be minor to 

moderate to the population, as there have been extensive impacts to Sargassum and associated 

communities, but recovery has been rapid. Because the Sargassum cycle occurs across a large 

portion of the Western Hemisphere (Frazier et al., 2015), because OCS oil- and gas-related 

operations rarely occur in dense aggregations, especially with respect to drilling operations, and 

especially because of the high reproductive rates of Sargassum, the incremental impacts of a 

proposed action on the population of Sargassum would be negligible. Non-OCS oil- and gasrelated vessel traffic is not expected to have a substantial impact on Sargassum and associated 

communities; however, declining coastal water quality as a result of eutrophication could, as 

described in Chapter 4.2 (Water Quality). Regardless, the incremental impact of a proposed action 

on the population of Sargassum would be negligible when considered in the context of cumulative 

impacts to the population. Impacts from changing water quality and climate change would be much 

more influential on Sargassum than OCS development and would still occur without the presence of 

OCS oil- and gas-related operations.

4.5.2.4 Incomplete or Unavailable Information

Although much is known about Sargassum and its life history, incomplete or unavailable 

information still remains. This incomplete or unavailable information includes information on the 

effects of in situ oil exposure and the factors impacting the movement patterns of Sargassum. 

BOEM used existing information and reasonably accepted scientific methodologies to extrapolate in 

completing the analysis above. BOEM has determined that there are few foreseeable significant 

adverse impacts to the Sargassum population associated with a proposed action, using publications 

such as Frazier et al. (2015), Gower and King (2011), Gower et al. (2013), and Powers et al. (2013). 

Gower and King (2011) and Gower et al. (2013) suggest that Sargassum is continually present in the 

west-central GOM and that it moves in a general west-to-east pattern during the growing season; 

however, movements at a finer temporal or spatial scale are more difficult to predict. Frazier et al. 

(2015) built upon these studies and developed a more finite life cycle for Sargassum that links the 

Sargasso Sea Sargassum populations with the GOM populations. With respect to the effects of 
4-160 Gulf of Mexico Multisale EIS

oiling from the Deepwater Horizon oil spill, Liu et al. (2014) noted that the toxicity or the presence of 

oil across the surface waters of the GOM was also variable at any given time, suggesting that it is 

difficult to predict the effects of Sargassum coming into contact with surface oil. Additionally, LindoAtichati et al. (2012) suggested that patterns of larval fish in the surface currents in the northern 

GOM were not consistent spatially or temporally and that they were highly dependent on mesoscale 

current structures like the Loop Current and associated eddies. Combined, these studies suggest 

that, as Sargassum is passively moved in the surface waters, its presence at any given location or at 

any given time is difficult to predict, especially as the population grows exponentially during the 

growing season. Ultimately, the ephemeral and wide-ranging nature across the northern GOM and 

the reproductive capabilities of Sargassum provide a life history that is resilient towards localized or 

short-term deleterious impacts, such as those expected to be associated with OCS oil- and gasrelated routine activities and noncatastrophic oil or SBF spills. Therefore, BOEM has determined 

that the incomplete information on Sargassum is not essential to a reasoned choice among 

alternatives and that the information used in lieu of the unavailable information is acceptable for this 

analysis.

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

Sargassum has a yearly cycle that promotes quick recovery from impacts. Therefore, most 

routine and accidental impact-producing factors would be expected to result in negligible impacts 

because they only impact a small percentage of the population and impacts would be limited in size 

and scope as new plants rapidly replace the impacted plants. In addition, the cumulative impact on 

Sargassum and associated communities for Alternative A would be minor to moderate due to the 

large scale of the impacts from the Deepwater Horizon oil spill to the population, the extremely largescale distribution, and the high reproductive rate of Sargassum. The incremental impacts of 

Alternative A to Sargassum and associated communities are expected to be negligible. 

4.5.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area 

Under this Alternative, impacts to Sargassum and associated communities would be mostly 

eliminated in the WPA area. Some remaining impacts would occur from vessels docking in the WPA 

and operating in the CPA or EPA, and from the cumulative impacts associated with previous OCS 

oil- and gas-related development and non-OCS oil- and gas-related activities. Any spill-related 

impacts would be limited to the areas along the WPA/CPA boundary and would not impact 

Sargassum communities beyond the area of the spill. While the CPA/EPA has the greatest potential 

for OCS oil and gas-related activity, Sargassum is common throughout the area and it routinely 

moves across the Gulf. As such, any localized impacts would be short-term as plants are replaced, 

resulting in no population-level impacts, and therefore, impact conclusions do not differ from 

Alternative A, which are negligible.
Description of the Affected Environment and Impact Analysis 4-161

4.5.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Under this Alternative, impacts to Sargassum and associated communities would be mostly 

eliminated in the CPA/EPA area. Some remaining impacts would occur from vessels docking in the 

CPA and operating in the WPA, and from the cumulative impacts associated with previous OCS oiland gas-related development and non-OCS oil- and gas-related activities. Any spill-related impacts 

would be limited to the areas along the WPA/CPA boundary and would not impact Sargassum

communities beyond the area of the spill. While the WPA is a smaller area with less projected 

activity than is proposed for the CPA/EPA, Sargassum is common throughout the area and it 

routinely moves across the Gulf. As such, any localized impacts would be short-term as plants are 

replaced, resulting in no population-level impacts, and therefore, impact conclusions do not differ 

from Alternative A or B, which are negligible.

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

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

Blocks South of Baldwin County, Alabama, Stipulations

Under this Alternative, impacts to Sargassum would be similar to those described in 

Alternative A, which are negligible. Sargassum moves in the Gulf of Mexico over great spatial 

scales and it would be expected to move in and out of these currently available unleased blocks

depending on prevailing meteorological processes. Additionally, the exclusion of any or all of the 

blocks subject to these stipulations would remove only a relatively small number of blocks (<4%) and 

would not be expected to reduce the potential for any of the impacts decribed in Alternatives A, B, 

and C.

4.5.2.9 Alternative E—No Action

Under Alternative E, a proposed lease sale would be cancelled and the potential for impacts 

from routine activities and accidental events would be none. Under this Alternative, impacts to 

Sargassum would be limited to cumulative impacts associated with past, present, and future OCS 

oil- and gas-related development and non-OCS oil- and gas-related activities. Sargassum moves in 

the Gulf of Mexico over great spatial scales and it would be expected to move in and out of the 

previously leased blocks depending on prevailing meteorological processes. In addition, many 

blocks already have OCS oil- and gas-related development, and Sargassum would continue to be 

impacted by routine activities and accidental events from pre-existing OCS oil- and gas-related 

development, although future impacts would likely be negligible. 

4.6 LIVE BOTTOM HABITATS

This chapter describes shallow-water hard/live bottom habitats in Gulf of Mexico OCS 

planning areas. Hard bottoms are naturally occurring, rocky, consolidated substrates that are 

geological (e.g., exposed sedimentary bedrock) or biogenic (e.g., carbonate relic coral reef) in origin. 

These habitats occur throughout the GOM but are relatively rare compared with the soft bottoms that 

are ubiquitous. Hard bottoms, particularly those having measurable vertical relief, can serve as 
4-162 Gulf of Mexico Multisale EIS

important habitat for a wide variety of marine organisms. Encrusting algae and sessile invertebrates 

such as corals, sponges, sea fans, sea whips, hydroids, anemones, ascidians, and bryozoans may 

attach to and cover hard substrates, thereby creating “live bottoms,” a term first coined by Cummins 

et al. (1962). The attached flora and fauna of live bottoms, such as large sponges and structureforming corals, further enhance the structural complexity of the benthic environment. Complex 

structure offers shelter that can be attractive to smaller invertebrates and fishes (Fraser and 

Sedberry, 2008), which, in turn, can provide food for a variety of larger fishes, including some 

commercially important fisheries (Szedlmayer and Lee, 2004; Gallaway et al., 2009). Refer to 

Chapter 4.7 (Fishes and Invertebrate Resources) and the Essential Fish Habitat Assessment white 

paper (USDOI, BOEM, 2016d) for more detail. Seagrasses can also be considered a type of live 

bottom, but they have very different physical characteristics and species assemblages than the 

above and are thus analyzed separately in Chapter 4.3.1. 

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

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

the Topographic Features Stipulation. The Live Bottom (Pinnacle Trend) Stipulation (Appendix D) 

has historically been applied to specific lease blocks in the CPA and EPA (Figure 4-17, areas shown 

in red) with the highest known concentrations of other live bottom features. These features are 

much smaller in size than the topographic features. Live bottom habitats found outside these 

stipulation lease blocks are not specifically included in the stipulation but are still given site-specific 

protections by BOEM during site-specific plan reviews (Appendix B). In Figure 4-17, the smaller 

black polygons represent the 38 named topographic features; selected fishery management areas 

on the West Florida Shelf, known to have high concentrations of live bottoms, are shown in gray. 

The GOM live bottoms are not limited to the features/areas shown in Figure 4-17. 

Figure 4-17. Lease Blocks Subject to the Topographic Features and Live Bottom (Pinnacle Trend) 

Stipulations.
Description of the Affected Environment and Impact Analysis 4-163

4.6.1 Topographic Features and Associated Communities

This analysis considers the reasonably foreseeable impacts of a proposed action’s routine 

activities, accidental events, and the incremental contribution to cumulative impacts on GOM 

topographic features and these physical features’ associated benthic communities (hereafter 

referred to as “topographic features”) over a 50-year period. Because a catastrophic oil spill is not 

considered reasonably foreseeable, those potential impacts (including long-term recovery) are 

addressed in the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017). The impact 

significance criteria and resulting conclusions presented here (Table 4-13) focus on the overall 

functioning, resilience, and ecosystem-level importance of topographic features throughout U.S. 

waters of the GOM.

Because of the similarity and overlap of the effects of many oil- and gas-related activities that 

occur in the OCS, the impact-producing factors considered for topographic features can be divided 

into three broad categories: drilling and exploration operations; vessel operations; and oil spill and 

associated cleanup activities. The impact-producing factors evaluated for this resource are listed 

below:

• Drilling, Exploration, and Decommissioning

− Bottom-disturbing activities (Chapter 3.1.3.3.2) 

− Deposition of sediments onto the seafloor (Chapter 3.1.3.3.3) 

• Vessel Operation

− Bottom-disturbing activities (Chapter 3.1.3.3.2) 

− Loss of debris

• Accidental Spills and Associated Cleanup

− Spills resulting from surface or subsea sources (Chapter 3.2.1) 

− Sediment burial

− Chemical and drilling-fluid spills (Chapter 3.2.6) 

− Cleanup operations not related to vessel operation (Chapter 3.2.8) 

An in-depth analysis of these potential impact-producing factors determined that, although 

many may occur within the GOM, few could occur at an extent sufficient to cause impacts to the 

topographic features as a whole (Table 4-13), partly because the topographic features are spread 

widely across the GOM. The potential magnitude of impact for each of the analyzed impactproducing factors is provided in Table 4-13 to help the reader quickly identify the level of potential 

impacts for each impact-producing factor. The impact-level definitions and the analyses supporting 

these conclusions are then discussed in detail in this chapter.
4-164 Gulf of Mexico Multisale EIS

Table 4-13. Topographic Features Impact-Producing Factors That Are Reasonably Foreseeable.

Topographic Features Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Bottom-Disturbing Activities Associated with Drilling, Exploration, and Decommissioning

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation Moderate Moderate Moderate Negligible None

Bottom-Disturbing Activities Associated with Vessel Operations

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation Moderate Moderate Moderate Negligible None

Accidental Impacts

Bottom-Disturbing Activities Associated with Drilling, Exploration, and Decommissioning

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation Moderate Moderate Moderate Negligible None

Chemical and Drilling-Fluid Spills

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation Moderate Moderate Moderate Negligible None

Bottom-Disturbing Activities Associated with Vessel Operations

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation Moderate Moderate Moderate Negligible None

Oil Spills and Associated Cleanup Activities

Large and Small Spills Resulting from Surface or Subsea Sources

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation Moderate Moderate Moderate Negligible None 

Cleanup Operations Not Related to Vessel Operation

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation Moderate Moderate Moderate Negligible None

Cumulative Impacts

Incremental 

Contribution2 Negligible Negligible Negligible Negligible None

OCS Oil and Gas3 Negligible

Non-OCS Oil and Gas4 Negligible to

Moderate

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the 

same geographic range and within the same timeframes as a proposed action, but they are not related 

to the OCS Oil and Gas Program.
Description of the Affected Environment and Impact Analysis 4-165

Impact-Level Definitions

For this analysis, the following definitions were used to categorize impacts to topographic 

features: 

• Negligible – Impacts to topographic feature communities are largely 

undetectable. There is some potential for even undetectable impacts to cause 

slight changes to a local community’s species abundance and composition, 

community structure, and/or ecological functioning, but any such changes would 

be spatially localized, short term in duration, and would not impact other 

topographic features.

• Minor – Impacts to topographic feature communities are detectable but cannot 

be distinguished from natural variation. Such impacts could result in noticeable 

changes to a local community’s species abundance and composition, community 

structure, and/or ecological functioning, but would be spatially localized, short 

term in duration, and recovery would be expected.

• Moderate – Impacts to topographic feature communities that result in 

substantial, population-level changes in species composition, community 

structure, and/or ecological functioning. These impacts would be expected to be 

spatially extensive, spanning across several topographic features, but impacts 

are expected to result in temporary changes and recovery would be likely.

• Major – Impacts to topographic feature communities that result in substantial, 

population-level changes in species composition, community structure, and/or 

ecological functioning. These impacts would be expected to be spatially 

extensive and noticeably alter the overall status of many topographic features 

communities in the GOM. Long-term recovery to pre-impact community 

structure, species abundance, or ecological function is unlikely.

The impact-producing factors related to the release of toxins and sediments were not carried 

forward for further analysis because these discharges are managed through the NPDES permitting 

process or MARPOL Annex V Treaty. Regulation and enforcement of these laws is conducted by a 

number of agencies, including USEPA, NOAA, BSEE, and USCG, and is intended to ensure that 

water quality is maintained at an acceptable level. Compliance is assumed; therefore, these factors 

are not further analyzed in this chapter. Similarly, the release of marine debris is also regulated by 

the USCG and MARPOL and is strictly prohibited; this is reinforced by NTL 2015-BSEE-G03, which 

imposes marine debris awareness and prevention measures on the oil and gas industry. 

Historically, NTL 2015-BSEE-G03 has been made a binding part of leases through the Protected 

Species Stipulation. As such, accumulation of debris at levels great enough to impact a topographic 

feature is unlikely. Another impact-producing factor not carried forward for further analysis is 

impacts resulting from a vessel sinking and coming to rest on a topographic feature. An OCS oiland gas-related vessel sinking is a rare event and it is not reasonably expected that a vessel sinking 

in the OCS would come to rest on a topographic feature. Sediment burial and surface response 
4-166 Gulf of Mexico Multisale EIS

operations that would occur during an oil spill were also not carried forward. Response operations 

may occur at the water surface above a topographic feature; however, none of the technologies 

employed to remove oil at the surface operate at a depth deep enough to impact a topographic 

feature. An accidental sediment burial of organisms during a spill was also not carried forward 

because it is not reasonably foreseeable that this type of event would occur outside of a catastrophic

situation. A review of BSEE’s records show that an accidental burial event has not occurred since at 

least 2006, which was when reporting requirements changed to require reporting of this type of 

event (USDOI, BSEE, 2015d). As such, only the following impact-producing factors were carried 

forward to a full analysis for routine activities and accidental events:

• Routine Activities

− Drilling, exploration, and decommissioning (Bottom-disturbing activities) 

− Vessel operation (Bottom-disturbing activities)

• Accidental Events

− Drilling, exploration, and decommissioning

 Bottom-disturbing activities 

 Chemical and drilling-fluid spills 

− Vessel operation (bottom-disturbing activities) 

− Oil spill and associated cleanup

 Large and small spills resulting from surface or subsea sources 

 Cleanup operations not related to vessel operations

Historical Protections of Topographic Features

In the Gulf of Mexico, topographic features are known to function as large-sized, hard 

substrate habitats that enable settlement of sensitive benthic organisms, concentrate fishes, and 

substantially contribute to the ecology of the GOM. Many of these features have been identified as 

locations of particular value that may require a greater degree of protection from OCS oil- and gasrelated activities. As such, beginning in 1973, BOEM’s predecessor agency established and 

implemented a Topographic Features Stipulation (also referred to here just as “stipulation”) that 

applies conditions to OCS oil- and gas-related activities occurring in the vicinity of these features.

Adherence to the provisions of this stipulation helps protect the resources by distancing OCS 

oil- and gas-related activities away from the most sensitive areas of topographic features in order to 

minimize negative impacts of routine activities and accidental events. Historically, this stipulation 

has been applied consistently to all leases in OCS areas with defined topographic features. The 

stipulation establishes a No Activity Zone around the most ecologically sensitive core area of each 

identified topographic feature, within which no bottom-disturbing activities are allowed. Additionally, 
Description of the Affected Environment and Impact Analysis 4-167

BOEM extends a 500-ft (152-m) buffer around each of these No Activity Zone boundaries, further 

restricting bottom-disturbing activity. The additional 500-ft (152-m) buffer policy was developed in 

consultation with NOAA to further protect areas of topographic features that were not originally 

included in the defined No Activity Zones. In addition, for most of the features, the stipulation also 

establishes variably sized concentric shunting zones surrounding the No Activity Zones, within which 

BOEM requires that drill cuttings and drilling fluids be shunted to near the seafloor to minimize the 

seafloor area affected by the cuttings and fluids.

Refer to Appendix D for further details of the Topographic Features Stipulation and NTL 

2009-G39, “Biologically-Sensitive Underwater Features and Areas,” which provides information and 

consolidates guidance to help operators understand BOEM’s requirements related to sensitive 

shallow-water benthic habitats. These requirements are designed to prevent or limit any impacts to 

topographic features from routine activities and accidental events. This analysis assumes that these 

(or functionally equivalent) protections will continue to be a requirement for OCS oil- and gas-related 

activities resulting from a proposed action throughout the 50-year analysis period. Furthermore, the 

Secretary of the Interior has decided in the Record of Decision for the Five-Year Program to include 

the Protection of Biologically Sensitive Underwater Features as landscape mitigation for the 

10 proposed lease sales in the GOM (USDOI, 2017).

4.6.1.1 Description of the Affected Environment

Topographic features (also called banks) are a subset of hard bottom habitats found in the 

GOM that are large enough in individual size to have a particularly important role in the GOM 

ecosystem. Although large in size, these features (and hard bottom habitats as a whole) are 

relatively rare compared with the expansive soft bottoms found throughout the central and western 

GOM (Parker et al., 1983). Topographic features can be created through the uplift of bedrock by 

underlying salt diapirs and the exposure of fossilized barrier islands, or they can be formed from relic 

carbonate reefs (Rezak and Bright, 1981a and 1981b; Berryhill et al., 1987). Regardless of origin, 

these subsea banks provide areas of hard substrate that support benthic and fish communities with 

relatively high biomass, diversity, and abundance. The structurally complex habitats of these 

features also provide shelter, food, and nursery grounds that support large numbers of commercially 

and recreationally important fishes (Johnston et al., 2015; Nash et al., 2013). Many of these habitats 

remain relatively pristine and have a high aesthetic and scientific value in part because they 

represent ecological and/or geographic extremes for many species (Rezak and Bright, 1981a; Nash 

et al., 2013; Johnston et al., 2015).

Within the GOM, BOEM has identified 38 topographic features with sufficiently unique 

geography and ecology (Rezak and Bright, 1981a; Rezak et al., 1983) to continue warranting some 

degree of protection from OCS oil- and gas-related activities. There are 22 topographic features in 

the WPA, 16 in the CPA, and 0 in the EPA (Figure 4-17). As detailed above, in previous lease 

sales, all of these banks were provided a designated No Activity Zone, in which all OCS oil- and gasrelated bottom-disturbing activities were prohibited. The No Activity Zones were defined based on a 

specific depth contour for each feature. They are designed to protect the most sensitive area of the 
4-168 Gulf of Mexico Multisale EIS

features. In addition, EFH programmatic consultation with NMFS specified that drilling should not 

occur within 152 m (500 ft) of a No Activity Zone of a topographic feature. Any bottom-disturbing 

activities within that buffer distance would first require project-specific EFH consultation with NMFS. 

Most of the topographic features have also been given additional restrictions beyond the No Activity 

Zone, specifically the drilling discharge shunting zones. 

Figure 4-18 presents an illustrative example of the ecology of topographic features, showing 

the various types of habitats found at different depths. Each of the labels represents different 

ecological zones common to topographic features. Note that rarely do all of the possible zones 

occur on a single feature. For example, East Flower Garden Bank contains all but one of the 

ecotones, i.e., the Millepora-Sponge Zone. This zone occupies depths comparable to the DiploriaMontastraea-Porites Zone on the claystone-siltstone substrate of the Texas-Louisiana midshelf 

banks. Crusts of hydrozoan corals (Millepora alcicornis), sponges, and other epifauna typically 

occupy the tops of outcrops in this zone, but scleractinian corals and coralline algae are rare (Rezak 

et al., 1990). 

Figure 4-18. Ecological Representation of Common Features on Topographic Features in the Gulf of 

Mexico. 
Description of the Affected Environment and Impact Analysis 4-169

Topographic features in the GOM are subject to an array of environmental conditions, 

resulting in a large number of ecological community types. This includes a range from the highly 

productive hermatypic (i.e., reef building) corals found at the Flower Garden Banks to habitats such 

as Dunn Bar, which possess less productive and less diverse benthic habitats but are still known to 

concentrate fishes (Rezak and Bright, 1981b; Nash et al., 2013).

Bank Classification

Shelf-Edge Banks

The shelf-edge banks generally exhibit the greatest range of habitat types of all the 

topographic features because they have the greatest vertical relief (Rezak et al., 1983). In general, 

banks that have the greatest vertical relief also possess the greatest number of habitat categories. 

The habitats of topographic features can be classified into seven categories. All of these categories 

can be found on the various shelf-edge banks, although not all of them occur simultaneously at the 

same bank (Rezak et al., 1983). These habitats range from the reef-building, shallow-water corals, 

the most complex and diverse of the habitat types, to less diverse habitats found in the high-turbidity 

nepheloid layer. The nepheloid layer is a zone of suspended sediment-laden water of variable 

density and vertical size that persists above the seafloor. It can be a controlling factor for the many 

live bottom species that are sensitive to turbidity (Rezak et al., 1990), exerting a considerable 

influence on species’ bathymetric and geographic distribution. Generally, high levels of suspended 

sediments can limit species diversity and abundance, at least for the sessile benthic live bottom 

species considered in this chapter. Light penetration, depth, and sediment loading are the most 

influential environmental controls on communities that colonize topographic features (Rezak et al., 

1983). There is a direct relationship between light levels at depth and the biodiversity of these 

habitats.

Among the shelf-edge banks, the Flower Garden Banks and McGrail Bank have been 

identified as exceptionally important components of the GOM ecosystem. These banks represent 

the northernmost colonies of hermatypic corals and may provide larvae/recruits for other coral reefs 

far away (Goodbody-Gringley et al., 2012). Shelf-edge banks also serve as seasonal feeding, 

mating, and nursery grounds for many species, such as manta and devil rays, whale sharks, and 

hammerhead sharks (Burks et al., 2006; USDOC, NOAA, 2010c; Johnston et al., 2013; Johnston 

et al., 2015). Additionally, many of these banks are important for commercial or recreational 

fisheries because they provide structurally complex habitat for recruitment and concentrate 

harvestable quantities of fish (Rezak et al., 1983). There is also a diverse group of tropical reef fish 

species found on these banks. There are at least 175 tropical reef species that have been observed 

within the high-diversity zone at the Flower Garden Banks (Dennis and Bright, 1988; Pattengill, 

1998).

Midshelf Banks

The midshelf banks typically have less vertical relief than the shelf-edge banks, and they 

also occur in waters with reduced light penetration (due to higher primary production and/or higher 
4-170 Gulf of Mexico Multisale EIS

sediment loading). As such, hermatypic coral reefs are rare and thought to be limited to Stetson 

Bank (part of the Flower Garden Bank National Marine Sanctuary). Dominant benthic species on 

these banks are algaes, sponges, and ahermatypic (i.e., non-reef building) corals. The nepheloid 

layer often enfolds most portions of these banks because of their reduced vertical relief (at least 

compared with shelf edge banks). The presence of the nepheloid layer can influence light 

penetration and ultimately reduce biodiversity, with the turbid conditions favoring fewer but more 

robust and resilient species. Midshelf banks are known to concentrate many pelagic species of 

fishes and are visited regularly by commercial and recreational fishermen (Simmons et al., 2014).

South Texas Banks

The South Texas Banks are geographically and geologically distinct from the shelf-edge and 

midshelf banks (Rezak and Bright, 1981b; Berryhill et al., 1987). Several of the South Texas Banks 

are low-relief banks comprised of a series of patch-reef habitats. Some of these banks were created 

from the exposure of fossilized shorelines along the prehistoric coastline, or from drowned reefs 

created during a period when sea levels were considerably lower. These banks generally exhibit 

reduced biotic diversity. They have lower relief than the other bank types, fewer hard-substrate 

outcrops, and higher sediment loading due to the presence of a nepheloid layer at many of the 

banks (Rezak et al., 1983). The dominant benthic species on the South Texas Banks include 

sponges, hydroids, octocorals, and ahermatypic corals, although portions of these banks remain 

barren (Rezak and Bright, 1983; Dokken et al., 1993). Yet these banks are still known to provide 

habitat for many species of commercially and recreationally important fishes, which could be related 

to their relatively close proximity to the shoreline (Simmons et al., 2014).

Environmental Sensitivity of Banks

The importance of these topographic features has long been understood by BOEM and its 

predecessor agencies. It is also known that the same geologic processes that create some types of 

topographic features (i.e., salt domes) also create reservoirs where hydrocarbons can become 

trapped and subsequently harvested. As such, in the 1970’s, BOEM’s predecessor agency 

developed the Topographic Features Stipulation to ensure that the most sensitive sections of these 

features were not negatively impacted by OCS oil- and gas-related activities. The primary concern 

was sediment deposition and subsequent smothering of organisms during drilling operations. As 

such, BOEM (formerly MMS) funded a series of exploratory cruises to better understand the ecology 

of these banks. The result was the creation of an environmental priority index that rates the 

sensitivity of the various topographic features (Rezak and Bright, 1981a). In order of decreasing 

sensitivity, the following classification was used: 

(1) Shelf-edge, carbonate banks possessing clear-water coral reefs and AlgalSponge Zones, transitional assemblages approximating the Antipatharian Zone 

and Nepheloid Zone (surrounding depths of 276-656 ft [84-200 m], crests 

49-246 ft [15-75 m]).
Description of the Affected Environment and Impact Analysis 4-171

(2) Midshelf, Tertiary-outcrop banks bearing clear-water, Millepora-Sponge Zone 

and turbid-water-tolerant Nepheloid Zone (surrounding depths of 164-203 ft 

[50-62 m], crests 59-131 ft [18-40 m]).

(3) Midshelf and South Texas carbonate banks bearing poorly developed elements 

of the Algal-Sponge Zone, transitional Antipatharian Zone assemblages, and 

Nepheloid Zone (surrounding depths of 328-361 ft [100-110 m], crests 

220-240 ft [67-73 m]).

(4) Midshelf and South Texas banks bearing turbidity-tolerant assemblages 

approximating the Antipatharian Zone and Nepheloid Zone (surrounding depths 

of 197-262 ft [60-80 m], crests 184-230 ft [56-70 m]).

From this index, MMS (BOEM’s predecessor) developed the No Activity Zones and 

additional discharge restrictions. Features most sensitive to turbidity were given the greatest levels 

of protection. For example, the Flower Garden Banks were given the most generous No Activity 

Zone and a 4-mi (6-km) zone with discharge restrictions. Other sensitive banks, such as McGrail 

Bank, were given a No Activity Zone outlining the most sensitive habitats along with a 1-mi (1.6-km) 

zone and a 3-mi (4.8-km) zone with varying degrees of discharge regulations. Banks such as 

Sackett Bank have only a No Activity Zone and a 3,280-ft (1,000-m) discharge shunting zone. 

Finally, lower relief banks with a relatively high degree of turbidity tolerance, such as Big Adam 

Bank, only have a No Activity Zone.

There is evidence of a large-scale die-off of seaweeds and rhodoliths on several topographic 

features (Sackett and Ewing Banks) that occurred in 2010, possibly related to changes in 

environmental conditions and, as of 2013, there had been only limited recovery (Felder et al., 2014; 

Fredericq et al., 2014). The result was a reduction in diversity and abundance of benthic species at 

Ewing Bank, a reduction in abundance of benthic species at Sackett Bank, and an increase in 

injuries and population declines of decapods at both banks. Although there was little in situ

recovery, it was found that the rhodoliths on these banks may be functioning as a “seed bank” for 

these habitats (Felder et al., 2014; Fredericq et al., 2014). This suggests that there is an unknown 

environmental variable in-place that may be preventing in situ conditions required for recovery. The 

ultimate cause of these changes remains unknown; however, this area was subjected to ecosystemlevel insults from 2009 through 2012, in addition to the Deepwater Horizon explosion, oil spill, and 

response. With respect to oil exposure, the surface waters above Sackett and Ewing Banks had 

some degree of exposure, but there is no direct evidence that implicates oil-related impacts as the 

trigger for these changes (Felder et al., 2014; Fredericq et al., 2014). These banks are located in 

areas highly influenced by the outfall of the Mississippi River. Between 2009 and 2012, the 

Mississippi River outfall was highly irregular compared with normal outfall patterns (Pollak, 2013). 

From late 2009 to late 2010 and 2011, the Mississippi River maintained an exceptionally high flow 

rate with an abnormal seasonal pattern, and this was followed by record low outfall levels in 2012. 

These areas were also subjected to differing levels of hypoxia, with major hypoxic events occurring 

in the vicinity of Ewing Bank in the summers of 2009, 2010, and 2011 (USDOC, NOAA, 2010d and 

2015j). Although there were also many hypoxic events prior to 2009, these occurred during periods 
4-172 Gulf of Mexico Multisale EIS

of river outfall patterns exhibiting a more “normal” seasonal pattern, and these events may have 

contributed to the changes seen on these banks.

The banks of the northern GOM also experienced exponential population growth of the 

invasive lionfish (Pterois volitans and Pterois miles) during this same time period (USDOI, GS, 2015; 

Johnston et al., 2013). Lionfish are known to drive down diversity and abundance of benthic 

organisms, especially crabs, demersal fishes, and shrimps (Green et al., 2012). The lionfish 

expansion could result in a top-down control of grazers, ultimately preventing recolonization by 

seaweeds due to increased grazing on seaweed recruits by herbivores released from decapod 

predation due to lionfish pressure. It is a reasonable conclusion that the possible ecosystem-level 

changes on these two banks are the result of the cumulative impacts of many factors (e.g., 

Karnauskas et al., 2015) rather than a single cause-effect relationship (i.e., the Deepwater Horizon

oil spill).

Habitat Areas of Particular Concern and Endangered Species Act Listings

The NMFS has designated habitat areas of particular concern (HAPCs) within identified 

EFH. The direct and/or indirect impacts from cumulative OCS oil- and gas-related and non-OCS oiland gas-related activities on EFH are considered and summarized in the Essential Fish Habitat 

Assessment white paper (USDOI, BOEM, 2016d). The HAPC-designated areas are considered as 

providing particularly important habitat for federally managed fish species and are considered priority 

areas for research and conservation. Designation is based on ecological importance, sensitivity to 

potential stressors/impacts, and rarity (GMFMC, 2005 and 2010). The only bank designated as 

Coral HAPC is McGrail Bank (GMFMC, 2005 and 2010; Simmons et al., 2014). Hard-bottom HAPCs 

include Sonnier Bank, Geyer Bank, Bouma Bank, Rezak Bank, Sidner Bank, Alderice Bank, Jakkula 

Bank, and parts of McGrail Bank (GMFMC, 2005 and 2010; Simmons et al., 2014). The HAPC 

designation has no regulatory consequences for BOEM-permitted activities; however, BOEM does 

consult with NMFS on issues related to HAPCs when appropriate. In 2014, 20 additional coral 

species were listed as threatened under the ESA, and several of these species are found in the 

northern GOM (Federal Register, 2014b). For analysis and impact conclusions specific to these 

protected species, refer to Chapter 4.9.5. 

4.6.1.2 Environmental Consequences

4.6.1.2.1 Routine Activities

The reasonably foreseeable potential routine impact-producing factors that could affect 

topographic features in the GOM are caused by bottom-disturbing activities that may occur during 

drilling, exploration, and decommissioning operations and vessel operations.

Drilling, Exploration, and Decommissioning Operations

The term bottom-disturbing activities includes any activity that results in the disturbance of 

the seafloor during the exploration, production, or decommissioning phase of OCS operations. This 

includes (but is not limited to) drilling activities (Chapters 3.1.2 and 3.1.3.1), structure installation 
Description of the Affected Environment and Impact Analysis 4-173

and removal (Chapters 3.1.3.3 and 3.1.6), and pipelaying activities. Regardless of the activity, the 

severity of the impact to topographic features is the same, although the extent of the impact would 

vary in direct proportion to the material’s size.

The bottom-disturbing activity with the largest areal impact would be the discharge of muds 

and cuttings into the water column. Drilling operations in close vicinity to topographic features could 

deposit large amounts of sediment onto the features (maximum amounts estimated to be 

approximately 2,000 metric tons) (Neff, 2005). This could have severe impacts, including increased 

stress as the organisms cope with the increased sediment load, a decline in production due to 

decreased light, or mortality caused by smothering (Wilber et al., 2005). Sedimentation of 

uncolonized substrates could also render these areas uninhabitable for future recruits settling on the 

topographic feature. However, because of the distancing and shunting requirements of the 

anticipated Topographic Features Stipulation, these potential impacts are reduced to a negligible 

level.

The placement of any structures or equipment on the seafloor could also result in substantial 

impacts to the benthic communities on the topographic features. Any object placed on the seafloor 

could result in the crushing deaths of any organisms contacted during emplacement activities. 

Mortality due to smothering could also occur if sediments are moved from the seafloor to a new 

location (e.g., trenching a pipeline or emplacement of initial casings). Sedimentation of uncolonized 

substrates could also render these areas uninhabitable for future recruits to settle on the topographic 

feature.

Explosive severance for the removal of structures is another bottom-disturbing activity 

associated with OCS oil- and gas-related operations that can impact communities associated with 

topographic features. This could result in damage or death to any organisms within the vicinity of 

the blast or associated sediment plume, although long-term turbidity is not expected from platform 

removal operations. The shockwave from the blast could also potentially damage the underlying 

hard substrates required by many benthic organisms.

Without adherence to the distancing and shunting requirements of the Topographic Features

Stipulation, impacts to topographic features could be severe and long lasting. However, if the 

requirements of the Topographic Features Stipulation continue to be applied as expected, 

operations would remain a safe distance away from critical areas of topographic features. 

Additionally, restrictions on discharges would be in place and few organisms would experience 

substantial levels of sedimentation. It is expected that this stipulation would continue to be a 

requirement for OCS operators throughout the analysis period. Therefore, with adherence to the 

requirements of the Topographic Features Stipulation, impacts from drilling, exploration, and 

decommissiong operations would be negligible. 
4-174 Gulf of Mexico Multisale EIS

Vessel Operations

The only aspect of routine vessel operations that would result in bottom-disturbing activities 

that could impact portions of topographic features would be the use of anchors by vessels. Anchor 

damage is one of the greatest threats to the biota of the offshore banks in the GOM (Rezak and 

Bright, 1979; Rezak et al., 1985; Gittings et al., 1992a; Hudson et al., 1982). Anchors may break, 

fragment, or overturn corals, sponges, and other benthic organisms, and the anchor chain or cable 

may drag across and shear organisms off the substrate (Dinsdale and Harriott, 2004). This would 

result in consequences ranging from increased stress to mortality (Dinsdale and Harriott, 2004). 

Damage to a coral community may take 10 or more years to recover (Fucik et al., 1984; Rogers and 

Garrison, 2001).

The Topographic Features Stipulation and EFH programmatic consultation with NMFS 

prohibit bottom-disturbing activities, including anchoring, within the most sensitive areas of 

topographic features as defined by the individual bank’s No Activity Zones. Anchoring in other lesssensitive portions of topographic features, such as the outer edges, could be permitted, but only 

after BOEM’s subject-matter experts perform site-specific reviews of high-resolution survey 

information and apply any appropriate mitigating measures, as detailed in NTL 2009-G39, 

“Biologically-Sensitive Underwater Features and Areas” (Appendix D). Without adherence to the 

distancing requirements of the Topographic Features Stipulation, anchoring impacts to topographic 

features could be severe and long lasting. However, under the requirements of the Topographic 

Features Stipulation, which is a required mitigation as a result of the Five-Year Program’s Record of 

Decision, anchor placement from OCS oil- and gas-related vessels would not be allowed on or near 

the most sensitive areas of the features and impacts would be negligible. 

4.6.1.2.2 Accidental Events

The potential impact-producing factors resulting from accidental events on topographic 

features in the GOM include bottom-disturbing activities, releases of toxins and sediment into the 

water column, and oil spills and associated cleanup activities. Each of these impact-producing 

factors can occur during hydrocarbon extraction activities or during vessel operations.

Drilling, Exploration, and Decommissioning Operations

Bottom-Disturbing Activities

Reasonably foreseeable accidental bottom-disturbing activities include accidental overboard 

losses of equipment, either during vessel-platform transfer operations or during vessel transits; 

equipment loss overboard from platforms; severe weather, causing underwater equipment 

movement; or operator error during equipment placement (e.g., setting an anchor in the wrong 

location). Regardless of the cause, the consequence would be crushing and the likely mortality of 

contacted benthic organisms. The areal extent of impact would be directly related to the size of the 

equipment making contact. Larger pieces of equipment could also influence water-flow patterns on 

or around topographic features, potentially influencing the movement of larvae and food. However, 

any equipment that is deposited on the seafloor would also become a new hard substrate available 
Description of the Affected Environment and Impact Analysis 4-175

for settlement by sessile benthic organisms, with potential subsequent ecological benefits. Any 

recovery operations would have to abide by the Topograhic Features Stipulation’s requirements, 

including restrictions on bottom-disturbing activities.

Without adherence to the distancing requirements of the Topographic Features Stipulation, 

such impacts to topographic features could be severe and long lasting. However, if the distancing 

requirements of the stipulation are applied and adhered to, the probability of such events would be 

small. Because of the overall unlikelihood of such events and the inherently limited nature of any 

such impacts’ size and scope, the overall impact of accidental bottom-disturbing activities is 

expected to be negligible. 

Chemical and Drilling-Fluid Spills

Accidental spills, such as from a platform or vessel, could include releases of substances 

such as diesel fuel, marine paint, drilling fluids, and untreated sewage, or those that could occur 

through the incorrect separation of cuttings and drilling muds (Chapter 3.2.6). Most spills on the 

OCS would have little impact on the organisms of a topographic feature because spills of this type 

are expected to be relatively small, and it is expected that spilled substances would either remain in 

the surface waters or would be rapidly diluted and dispersed. For substances such as drilling muds, 

an accidental release could have substantial impacts to a topographic feature as those materials 

usually settle rapidly to the seafloor, smothering any contacted organisms, some of which cannot 

cope with large quantities of sediments. Exposures to concentrated drilling muds can result in a 

wide range of impacts to corals, ranging from mortality to multiple sublethal responses to no 

response at all (Thompson, 1979). Such impacts would likely be proportional to the size of the spill 

and the vicinity of the spill to topographic features. The composition of muds is strictly regulated, 

and discharges of cuttings/muds are tested to ensure that toxicity levels are below the limits allowed 

by NPDES permits (USEPA, 2004, 2007, and 2009b). It is expected that such an accidental spill 

would be stopped quickly or would be relatively small given the limited amounts that are typically 

transfered at one time.

Without adherence to the distancing requirements of the Topographic Features Stipulation, 

impacts to topographic features from chemical and drilling-fluid spills could be as great as 

moderate. However, if the distancing requirements of the Topographic Features Stipulation are 

applied, such impacts would be minimized. This would allow more time and distance for dilution and 

dispersion of substances. Given the inherently low likelihood of an accidental spill, and assuming 

adherence to the Topographic Features Stipulation and the low likelihood of this type of spill 

occurring near a topographic feature, the impact of accidental releases of toxins into the water 

column is expected to be negligible. 

Vessel Operations

The only reasonably foreseeable aspect of vessel operations that could result in bottom 

disturbance of topographic features would be vessel anchoring. Anchor damage is one of the 

greatest threats to the biota of the offshore banks in the GOM (Rezak and Bright, 1979; Rezak et al., 
4-176 Gulf of Mexico Multisale EIS

1985; Gittings et al., 1992a; Hudson et al., 1982). Anchors may break, fragment, or overturn corals, 

sponges, and other sessile benthic organisms, and anchor chains or cables may drag across and 

shear organisms off the substrate (Dinsdale and Harriott, 2004). This could result in consequences 

ranging from increased stress to mortality (Dinsdale and Harriott, 2004). Such damage to a coral 

community may take 10 or more years to recover (Fucik et al., 1984; Rogers and Garrison, 2001).

Because of the Topographic Features Stipulation, such anchoring is not expected during 

routine activities. However, unplanned anchoring could occur as a result of an accident or during a 

life-threatening emergency situation on a vessel (e.g., loss of propulsion) to preserve the safety of 

the vessel and crew. In that case, impacts to benthic organisms on topographic features would be 

locally severe at the location where the anchor lands; however, impacts would be limited to that 

location and should not threaten communities across an entire topographic feature. In addition, an 

emergency requiring anchoring is expected to be a rare event. Without adherence to the distancing 

requirements of the Topographic Features Stipulation, such impacts to topographic features could 

be severe and long lasting at the specific location where accidental anchoring occurs. However, if 

the requirements of the Topographic Features Stipulation are applied, the chances of accidental 

anchor placement happening in the most sensitive areas of topographic features is low, and impacts 

of accidental anchoring events are expected to be negligible. 

Oil Spill and Cleanup Activities

Impacts that may occur to topographic features’ benthic communities as a result of an oil spill

would depend on the type of oil spill, the features’ distance from the spill, relief of the biological 

feature, and surrounding physical characteristics of the environment (e.g., turbidity). Oil transport 

and fate is discussed in Chapter 3.2.1.3, and oil spills <1,000 bbl and oil spills ≥1,000 bbl are 

discussed in Chapters 3.2.1.4 and 3.2.1.5, respectively. In large enough quantities, oil spills could 

result in lethal or sublethal impacts to organisms, including reduced fitness, growth, or reproduction. 

The depth of topographic features below the sea surface should minimize contact with surface oil 

where it is expected to be advected away or cleaned up by response crews.

If an oil spill occurs at depth in deep water and the oil is ejected under pressure, some oil 

would rise to the surface, but some oil droplets may become entrained deep in the water column 

(Boehm and Fiest, 1982), creating a subsurface plume (Adcroft et al., 2010). If this plume was to 

come in contact with the benthic organisms on a topographic feature, the impacts could be severe. 

Consequences could include mortality, loss of habitat, reduced biodiversity, reduced live bottom

coverage, changes in community structure, and reduced reproductive success (Reimer, 1975; 

Guzmán and Holst, 1993; Negri and Heyward, 2000; Silva et al., 2015). The extent and severity of 

impacts would depend on the location and weathering of the oil and the hydrographic characteristics 

of the area (Bright and Rezak, 1978; Rezak et al., 1983; McGrail, 1982; Le Henáff et al., 2012). 

Because all of the topographic features are located on the continental shelf and because upwelling 

events are generally limited to hurricanes, eddy formations, or when certain meteorological 

conditions exist (Walker, 2001; Collard and Lugo-Fernandez, 1999; Zavala-Hidalgo et al., 2006), 

contact of a small subsurface plume with a topographic feature would only occur under the most 
Description of the Affected Environment and Impact Analysis 4-177

ideal and unlikely conditions (such as in Silva et al., 2015). There is a possibility that, if a subsurface 

plume becomes entrained in the nepheloid layer, organisms in this layer could be greatly impacted. 

In shallow waters, this layer is typically restricted to the bottom 66 ft (20 m) of the water column 

(Bright et al., 1976; Bright and Rezak, 1978).

Use of chemical dispersants on a larger spill (refer to Chapter 3.2.8.2.2) would enable 

dispersed oil to mix into the water column and possibly impact benthic organisms on topographic 

features, similar to what was documented in Silva et al. (2015). For a surface spill, dispersed oil is 

not expected to reach the topographic feature (Guo et al., 2014; Lange, 1985; Tkalich and Chan, 

2002); however, if dispersants are applied to a subsurface plume, any dispersed oil in the water 

column that comes in contact with corals may evoke short-term negative responses, including 

reduced feeding and photosynthesis or altered behavior (Wyers et al., 1986; Cook and Knap, 1983; 

Dodge et al., 1984; Ross and Hallock, 2014). For larvae, the response may be even more profound, 

with implications for dispersant use during coral spawning season (Negri and Heyward, 2000; 

Goodbody-Gringley et al., 2013). There is some evidence that dispersant-treated areas may recover 

more rapidly than areas where oil is allowed to decay naturally (Lessard and Demarco, 2000).

For any accidental spill, it is also expected that a certain quantity of spilled oil may eventually 

settle on the seafloor due to the formation and settlement of “marine snow,” which involves a binding 

process with suspended sediment particles and/or consumption and excretion by phytoplankton 

(International Tanker Owners Pollution Federation Limited, 2002; Passow et al., 2012). It is 

anticipated that the greatest amount of oil adsorbed to sediment particles would occur close to the 

spill, with concentrations reducing with distance from the source. If the spill occurs very close to a 

topographic feature, the underlying benthic communities may become smothered by the settling 

particles and thereby exposed to hydrocarbons. Beyond that immediate area, impacts would be 

more limited due to particles biodegrading and dispersing. Sublethal impacts to benthic organisms 

from any such exposure may include reduced recruitment success, reduced growth, and reduced 

coral cover as a result of impaired recruitment (Rogers, 1990; Kushmaro et al., 1997).

A different type of impact could occur during a response operation in which drilling muds are 

pumped into a well to regain well control. It is possible that, during this process, such muds may be 

forced out of the well and deposited on the seafloor near the well site. If this were to occur, the 

localized impacts would be severe for the organisms buried; however, any impact beyond the 

immediate area would be very limited.

In conclusion, without adherence to the distancing requirements of the Topographic Features

Stipulation, oil-spill impacts to topographic features could be severe and long lasting due to the 

various mechanisms outlined above, including oiling, cleanup activities, toxins from dispersants, 

and/or bottom-disturbing activities. However, if the requirements of the Topographic Features 

Stipulation are applied as expected, these impacts should be negligible. 
4-178 Gulf of Mexico Multisale EIS

4.6.1.2.3 Cumulative Impacts

OCS Oil- and Gas-Related Impacts

The cumulative impact of OCS oil- and gas-related activities include routine bottomdisturbing activities (e.g., anchoring, structure emplacement and removal, and muds and cuttings 

discharges) and accidental events (e.g., bottom disturbance, the discharge of oil, and/or spill 

cleanup).

The OCS oil- and gas-related bottom-disturbing activities could result in the physical 

destruction of benthic habitat and organisms or the disturbance of local sediments leading to burial 

or increased stress. However, the proposed Topographic Features Stipulation has been in effect for 

decades, limiting historical OCS oil- and gas-related impacts, and it is expected to remain in effect. 

An example of this is the continued high degree of coral coverage and biodiversity documented by 

the long-term monitoring program at the Flower Garden Banks National Marine Sanctuary (Johnston 

et al., 2015). The area in the vicinity of the Sanctuary has seen a substantial amount of oil and gas 

production for decades, and overall coverage by benthic organisms has remained high and stable.

Impacts on topographic features could occur as a result of future OCS oil spills. To date, 

previous noncatastrophic spills have not had any identifiable impact (cumulative or otherwise) on 

any topographic features. Because of the physical properties of northern GOM oil, subsea oil spills 

generally rise quickly to surface waters before contacting benthic communities on topographic 

features, and the distancing requirements of the Topographic Features Stipulation further reduce the 

likelihood of contact. The depths of the crests of the topographic features are generally deep 

enough (>49 ft; >15 m) that surface oil should not reach benthic communities on topographic 

features in sufficient concentrations to cause impacts. As observed in Silva et al. (2015), the deep 

mixing of oil, particularly following use of chemical dispersants, is possible during unusually extreme 

weather events and could result in negative impacts if contact is made at sufficiently high 

concentrations. Excluding such an event, any dispersed surface oil reaching benthic communities of 

topographic features in the GOM should be at a low enough concentration to not cause discernible 

long-term impacts (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Dodge et al., 1984; Wyers et al., 

1986).

Continued adherence to the Topographic Features Stipulation’s restrictions would prevent or 

minimize most adverse impacts on the benthic communities of topographic features (refer to 

Chapter 2.2.4.1 and Appendix D). Overall, it is expected that, given adherence to the proposed 

stipulation, the OCS oil- and gas-related cumulative impacts will continue to be negligible. 

Non-OCS Oil- and Gas-Related Impacts

The potential cumulative impacts to topographic features from non-OCS oil- and gas-related 

sources include anchoring, fishing pressure, invasive lionfish, hurricanes, damage by recreational 

scuba diving, and environmental influences such as climate change and severe weather events.
Description of the Affected Environment and Impact Analysis 4-179

Most of these features are deep enough that recreational scuba diving activities are fairly 

limited. In most areas where such diving does occur (particularly the Flower Garden Banks), that 

activity is managed by other Federal agencies (e.g., the Flower Garden Banks National Marine 

Sanctuary), with management practices that protect habitats from modification or destruction.

Because many of the topographic features are found near established shipping fairways and 

are well-known fishing areas, vessel anchoring at a topographic feature could and has damaged the 

biota (refer to Chapter 3.3.2.2) with the degree of damage dependent on the size of the anchor and 

chain (Lissner et al., 1991).. Anchor damages incurred by benthic organisms may take more than 

10 years to recover (Fucik et al., 1984; Rogers and Garrison, 2001). Anchoring is currently 

prohibited within the boundaries of the Flower Garden Banks National Marine Sanctuary (which 

includes East and West Flower Garden Banks plus Stetson Bank) and for fishing vessels within the 

McGrail Bank Coral HAPC boundaries designated by NMFS and the Gulf of Mexico Fishery 

Management Council. The exact cumulative impact of non-OCS oil- and gas-related anchoring 

activities on topographic features is unknown.

Fishing pressure could alter fish community structure and potentially have a top-down trophic 

impact on fish populations, ultimately leading to ecosystem-driven impacts to the benthic community. 

This could occur through unsustainable harvest practices, although, most managed fish populations 

in the GOM are considered stable or recovering. Harvest is monitored and managed by NMFS and 

the Gulf of Mexico Fishery Management Council, and fish populations are not expected to be 

depleted to a point where benthic populations are impacted.

The recent invasion by lionfish is likely to alter some fish and invertebrate populations on 

topographic features over time (Johnston et al., 2015). The predatory nature of this fish, combined 

with its lack of natural predators in the GOM, suggests that a population explosion of lionfish could 

result in a trophic impact on benthic organisms. The result would be a decrease in biodiversity and 

abundance of many of the smaller organisms that use the seafloor habitats found on topographic 

features. Given the rapid spread of reported lionfish sightings across the GOM, it is possible that 

they are already present (if not yet documented) on portions of all of the topographic features. 

Therefore, the current impact level is not yet fully understood, but it seems likely to rise over time if 

lionfish populations continue to increase exponentially (Switzer et al., 2015).

Hurricanes are considered a rare event at any given location (refer to Chapter 3.3.2.9.3) but 

hurricane-associated water movement has the potential to cause localized impacts such as breaking 

branches of fragile shallow-water branching corals. Because hurricanes are a natural event that 

have regularly (if only intermittently) influenced environmental conditions surrounding topographic 

features, such impacts cannot be clearly distinguished from those of natural variation because 

benthic communities have adapted over millennia to deal with natural levels of severe weather.

Climate change-related effects have the potential to alter baseline environmental conditions 

throughout the GOM. An additional review of climate change is presented in the Five-Year Program 

EIS (USDOI, BOEM, 2016b), and there is extensive scientific literature available about climate 
4-180 Gulf of Mexico Multisale EIS

change in general. Of particular note for benthic communities on topographic features are the 

potential negative consequences that may be caused by the dual mechanisms of ocean acidification 

and increasing ocean temperatures. Ocean acidification can reduce bioavailability of calcium 

carbonate and thereby inhibit normal rates of calcification by exoskeleton-building corals and other 

calcifying marine organisms. Decreased calcification rates have been observed in numerous 

shallow-water zooxanthellate corals (Hofmann et al., 2010) and can inhibit growth and reproductive 

fitness because of the additional energy expended. Sustained, unusually high water temperatures 

are documented to cause coral bleaching, in which symbiotic zooxanthellae are expelled from coral 

polyps. Over time, a permanent temperature baseline shift could allow the northward expansion of 

species adapted to warmer waters, potentially altering the current community structure at 

topographic features. Other potential climate change-driven alterations of baseline environmental 

conditions could also have additional, unpredictable effects on sessile benthic organisms. For 

example, changing climatic conditions that alter the frequency and/or severity of severe weather 

events could impact communities since severe weather can also have secondary, non-natural 

impacts such as causing movement of abandoned fishing gear and exaccerbating accidental losses 

of equipment overboard. At present, the overall impact of climate change-related effects on 

topographic features is likely negligible. However, over the next 50 years, this impact level could 

rise to higher levels, even as great as moderate, should the most extreme impacts possible as a 

result of projected climate change-associated factors come to pass.

Adherence to the restrictions specified in the Topographic Features Stipulation has 

minimized the potential for routine activities or accidental events to impact topographic features. 

Assuming continued application of the stipulation as a result of a proposed action, the probability of 

OCS oil- and gas-related activities increasing the overall cumulative impact level is expected to 

remain low, and the incremental contribution of a proposed lease sale is negligible. In contrast, 

non-OCS oil- and gas-related cumulative impacts could damage and disrupt topographic features. 

Some of those potential effects are highly variable and unpredictable, but certain non-OCS oil- and 

gas-related impacts such as lionfish expansion and climate change-related effects are expected to 

worsen over time.

Based on current conditions, the overall cumulative impact of everything (OCS and non-OCS 

oil- and gas-related impacts) is currently negligible, with almost all impacts coming from non-OCS 

oil- and gas-related factors. However, this total impact level has the potential to rise substantially 

over the next 50 years to higher levels, as high as moderate, should projected trends of non-OCS 

oil- and gas-related factors (particularly climate change) continue or worsen. However, given the 

negligible contribution of a proposed lease sale to the overall cumulative scenario, it is reasonable to 

conclude that a single proposed lease sale would have no discernible effect on increasing the overall 

cumulative impact level over the next 50 years.

4.6.1.2.4 Incomplete or Unavailable Information

BOEM recognizes that there is incomplete or unavailable information related to topographic 

features in general and specifically in relation to routine activities, accidental events, and cumulative 
Description of the Affected Environment and Impact Analysis 4-181

impacts. However, the information that is known is adequate to come to a determination with 

respect to reasonably foreseeable impact-producing factors associated with a proposed action.

Research in offshore marine systems is logistically complex and requires substantial 

resources. As such, the total amount of research on these features and their communities is 

relatively limited, although BOEM and its predecessor agencies have funded numerous studies over 

the past 40 years. For example, our understanding of the possible impacts of surface oil spills to 

topographic features in the GOM was determined by combining research on the depth and 

concentration of the physical mixing of surface oil with the known depths of topographic features. 

Even though oil measurements were not collected at every feature under every condition, the 

available results suggest that, topographic features exist at depths deeper than lethal concentrations 

of oil would usually be expected (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 

2002; Rezak et al., 1983; Wyers et al., 1986). Mixing to depth might occur, but it would be limited to 

unusual combinations of conditions such as when tropical storms pass directly over oiled surface 

waters (e.g., Silva et al., 2015). Moreover, the amount of oil/dispersant mixture in that catastrophic

situation greatly exceeds the amounts considered in the “Accidental Events” analysis below. Given 

the geographic and temporal scope of a proposed action, it is believed that even impacts resulting 

from that particular scenario would still only have a slight impact on the overall status of the 

topographic features. However, the example demonstrates the point that the body of literature 

supporting the impact analysis is still growing and requires continual review by BOEM.

Since the 1970’s, BOEM and its predecessor agencies have supported continuous 

monitoring of the Flower Garden Banks for any impacts related to OCS oil- and gas-related 

activities. At the Flower Garden Banks, corals have generally flourished (refer to Johnston et al., 

2015, and the references therein) even as OCS oil- and gas-related activities have occurred 

sometimes just outside of the No Activity Zone. Since corals are generally considered to be more 

fragile than most other types of organisms found on topographic features, it is also reasonable to 

conclude that topographic features with more resilient organisms have also not been negatively 

affected by OCS oil- and gas-related development in the GOM. However, given the ecological 

sensitivity of benthic communities on topographic features, continued research and monitoring 

efforts are necessary to maintaining a sufficient understanding of the various potential OCS oil- and 

gas-related and non-OCS oil- and gas-related impacts. A recent example illustrates how conditions 

could potentially change. In August 2016, a routine National Marine Sanctuary/BOEM long-term 

monitoring cruise in East Flower Garden Bank documented a mortality event affecting corals and 

other benthic organisms in a localized area. At the time of this writing, tissue and water quality

samples have been collected but not yet analyzed, and no causes have been indicated. BOEM will 

continue cooperating with the Sanctuary and other partners to evaluate information as it becomes 

available and will update future Supplemental EISs as necessary.

Known information about potential impacts of a theoretical catastrophic spill is detailed in the 

Catastrophic Spill Events Analysis white paper (USDOI, BOEM, 2017) and further information was 

made available with the publication of the Trustees’ PDARP/PEIS in 2016 (Deepwater Horizon

Natural Resource Damage Assessment Trustees, 2016). The content of that report was reviewed 
4-182 Gulf of Mexico Multisale EIS

as part of this analysis. Some information related to impacts specific to the Deepwater Horizon

explosion, oil, spill, and response, such as long-term monitoring results, is still incomplete or 

unavailable. BOEM has determined that such additional information could not be obtained within the 

timeline contemplated in the NEPA analysis for this Multisale EIS. However, the currently available 

body of evidence supports past analyses and does not indicate severe adverse impacts directly 

linked to the Deepwater Horizon explosion, oil spill, and response for topographic features. 

Impending reports are not expected to reveal additional significant effects that would alter the overall 

conclusions about reasonably foreseeable impact-producing factors associated with a proposed 

action.

BOEM will continue to analyze and support the collection and analysis of the best available 

scientific information related to topographic features. BOEM used reasonably accepted scientific 

methodologies to extrapolate from existing information in completing this analysis and formulating 

the conclusions presented here. As noted above, BOEM has determined that the incomplete or 

unavailable information is not essential to a reasoned choice among alternatives; there is sufficient 

information in the scientific literature to evaluate the potential impacts of a proposed action and its 

alternatives.

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

Adherence to the proposed Topographic Features Stipulation would prevent or at least 

minimize most of the potential impacts on topographic features and associated benthic communities 

from routine activities and accidental events. During an accidental event causing bottom 

disturbance, the size and scope of the impact would be directly proportional to the size of the 

accident and its vicinity to topographic features, but it would generally be very localized. In the case 

of an accidental oil spill, it would be expected that the majority of oil would rise to the surface and 

that the most heavily oiled sediments would likely be deposited before reaching the topographic 

features. Any contact with spilled oil would likely cause sublethal effects to benthic organisms

because the distancing of activity would prevent contact with concentrated oil. In the unlikely event 

that oil from a subsurface spill reaches the biota of a topographic feature, the effects would be 

primarily sublethal and impacts would be localized. Most turbidity, sedimentation, and oil adsorbed 

to sediment particles would also be at low concentrations by the time the topographic features were 

reached, also likely resulting in primarily sublethal impacts. Impacts from an oil spill on topographic 

features are also reduced by the depth of the features and the currents that surround the features. 

Selection of this alternative would do little to change the overall cumulative impacts to topographic 

features. Overall, given adherence to the Topographic Features Stipulation (which is a required 

mitigation as a result of the Five Year Program’s Record of Decision), reasonably foreseeable 

impacts to topographic features from routine activities, accidental events, and the cumulative impact 

of a proposed action in the GOM is expected to be negligible.
Description of the Affected Environment and Impact Analysis 4-183

4.6.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM would hold a lease sale excluding the available unleased blocks 

in the WPA and would offer all available unleased blocks in the CPA and a portion of the EPA. 

Alternative B would not fundamentally alter the conclusions reached under Alternative A. The 

impacts of routine activities to topographic features would remain the same in the CPA as under 

Alternative A, while any potential impacts to topographic features in the WPA could be reduced. 

Overall, there are 22 topographic features in the WPA, 16 in the CPA, and 0 in the EPA. Any 

impacts resulting from accidental events in the CPA and/or EPA would remain relatively localized, 

and the number of features affected would be directly proportional to the size of the accident. An 

accident along the CPA/WPA border has the possibility to impact features in either planning area. 

This alternative would do little to change the overall cumulative impacts to topographic features. 

Many OCS lease blocks near the features are already leased, and non-OCS oil- and gas-related 

impacts are not expected to decrease. Overall, given adherence to the Topographic Features 

Stipulation (which is a required mitigation in the Five-Year Program’s Record of Decision), 

reasonably foreseeable impacts to topographic features from routine activities, accidental events 

and the cumulative impact of a proposed action in the GOM under Alternative B is expected to be 

negligible. 

4.6.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

Under Alternative C, BOEM would hold a lease sale excluding the available unleased blocks 

in the CPA/EPA and would offer all available unleased blocks in the WPA. Alternative C would not 

fundamentally alter the conclusions reached under Alternative A. The impacts of routine activities to 

topographic features would remain the same in the WPA while any potential impacts to topographic 

features in in the CPA/EPA could be reduced. Overall, there are 22 topographic features in the 

WPA, 16 in the CPA, and 0 in the EPA. Any impacts resulting from accidental events in the WPA 

would remain localized, and the number of features affected would be directly proportional to the 

size of the accident. An accident along the CPA/WPA border has the possibility to impact features in 

either planning area. This alternative would do little to change the overall cumulative impacts to 

topographic features. Many OCS lease blocks near the features are already leased, and non-OCS 

oil- and gas-related impacts are not expected to decrease. Overall, given adherence to the 

Topographic Features Stipulation (which is a required mitigation as a result of the Five-Year 

Program’s Record of Decision), reasonably foreseeable impacts to topographic features from routine 

activities, accidental events, and the cumulative impact of a proposed action in the GOM under 

Alternative C is expected to be negligible. 
4-184 Gulf of Mexico Multisale EIS

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, BOEM could hold a lease sale excluding leasing on any and/or all 

blocks subject to the Topographic Features, Live Bottom (Pinnacle Trend), and Blocks South of 

Baldwin County, Alabama, Stipulations. Topographic features could experience fewer impacts 

through further distancing of the OCS oil- and gas-related activities, thereby reducing the probability 

of impacts. An accidental spill may still reach a feature, but it is expected that the increased 

distance would provide more dispersal time as the spill travels the additional distance across 

unleased blocks. This alternative would do little to change the overall cumulative impacts to 

topographic features. Many OCS lease blocks near the features are already leased, and non-OCS 

oil- and gas-related impacts are not expected to decrease. Blocks subject to the Topographic 

Features Stipulation include any available unleased block in which a No Activity Zone or shunting 

zone may be applied. A total of 207 blocks within the CPA and 160 blocks in the WPA are affected 

by the Topographic Features Stipulation. For additional information related to the specific blocks 

that would be excluded, refer to Chapter 2.2.2.4. The exclusion of any of the other blocks subject to 

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

Stipulations would not be expected to change the impacts to topographic features because of the 

small number of those blocks and their distance from identified topographic features. Overall, given 

adherence to the Topographic Features Stipulation (which is a required mitigation as a result of the 

Five-Year Program’s Record of Decision), reasonably foreseeable impacts to topographic features 

from routine activities, accidental events, and the cumulative impact of a proposed action in the 

GOM under Alternative D is expected to be negligible. 

4.6.1.2.9 Alternative E—No Action

Under Alternative E, a proposed lease sale would be cancelled. Therefore, the potential for 

new incremental impacts would be none because new impacts to topographic features related to the 

cancelled lease sale would be avoided entirely. Continuing OCS oil- and gas-related impacts to the 

communities would be limited to existing impacts resulting from routine activities and accidental 

events, and the cumulative impacts associated with previous OCS lease sales and development and 

other ongoing non-OCS oil- and gas-related activities. BOEM’s existing stipulation and mitigation

practices already regulate these activities and should continue to limit the associated ongoing 

impacts to the negligible level.

Ongoing non-OCS oil- and gas-related activities are difficult to accurately estimate since the 

spatial and temporal characteristics of some factors are rapidly changing and since the necessary 

baseline information is still being collected; however, at present, these non-OCS oil- and gas-related 

activities have negligible impacts on topographic feature communities. However, the level of 

cumulative impacts could potentially become greater, even rising to moderate over time, should 

current trends of these factors continue or worsen, regardless of whether or not a lease sale would 

take place.
Description of the Affected Environment and Impact Analysis 4-185

4.6.2 Pinnacles and Low-Relief Features and Associated Communities

This analysis considers the impacts of routine activities, accidental events, and a proposed 

action’s incremental contribution to cumulative impacts on GOM pinnacle and low-relief features and 

their associated benthic communities (hereafter referred to as “feature communities”) over a 50-year 

period. This analysis is not exhaustive of all possible impacts of routine activities and accidental 

events; rather, it focuses on those related to a proposed action. A summary of the potential 

magnitude of impact for each of these impact-producing factors is provided in Table 4-14 to help the 

reader quickly identify the level of potential impacts for each relevant impact-producing factor. The 

impact-level definitions and the analyses supporting these conclusions follow in this chapter. 

Because a catastrophic oil spill is not considered reasonably foreseeable, those potential impacts 

(including long-term recovery) are addressed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2017). The impact significance criteria and resulting conclusions presented here 

(Table 4-14) focus on the overall functioning, resilience, and ecosystem level importance of live 

bottom pinnacles and low-relief feature communities throughout U.S. waters of the GOM. Postlease, 

site-specific analyses would focus more on the potential localized impacts of individual development 

activities (e.g., proposed drilling of a specific well) to individuals, discrete communities, and small 

patches of live bottom habitat. Those analyses would also detail site-specific protective mitigations

required prior to approval of such activities. Appendix B provides detail on some of the potential 

site-specific mitigations that could be applied as necessary.

Table 4-14. Pinnacles and Low-Relief Features Impact-Producing Factors That Are Reasonably 

Foreseeable

Pinnacles and

Low-Relief Features Magnitude of Potential Impact1 

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Bottom-Disturbing Activities and Drilling-related Sediment and Waste Discharges

With Mitigation Negligible Negligible Negligible Negligible None

Without Mitigation

Minor to Minor to Negligible to Negligible to None

Major Moderate Minor Minor

Accidental Impacts

Bottom-Disturbing Activities and Drilling-Related Sediment and Operational Waste Discharges

With Mitigation Negligible to Negligible toNegligible Negligible None

Minor Minor

Without Mitigation

Minor to Minor to Negligible to Negligible to None

Major Moderate Minor Minor

Oil Spills

With Mitigation Negligible to Negligible to Negligible Negligible None

Minor Minor

Without Mitigation

Minor to Minor to Negligible to Negligible to None

Major Moderate Minor Minor
4-186 Gulf of Mexico Multisale EIS

Cumulative Impacts

Incremental 

Contribution2

Negligible to Negligible to Negligible Negligible None Minor Minor

OCS Oil and Gas3 Negligible to

Minor

Non-OCS Oil and Gas4 Minor to

Major

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

Impact-Level Definitions

For this analysis, the definitions below were used to categorize impacts to pinnacles and 

low-relief features.

• Negligible – Impacts to pinnacle and low-relief feature communities are largely 

undetectable. There is some potential for even undetectable impacts to cause 

slight changes to a local community’s species abundance and composition, 

community structure, and/or ecological functioning, but any such changes would 

be spatially localized, short term in duration, and would not alter the overall 

status of GOM pinnacle and low-relief feature communities.

• Minor – Impacts to pinnacle and low-relief feature communities are detectable 

but cannot be distinguished from natural variation. Such impacts could result in 

noticeable changes to a local community’s species abundance and composition, 

community structure, and/or ecological functioning, but any such changes would 

be spatially localized, short term in duration, and would not alter the overall 

status of GOM pinnacle and low-relief feature communities.

• Moderate – Impacts to pinnacle and low-relief feature communities detectably 

cause substantial, population-level changes in species composition, community 

structure, and/or ecological functioning. These impacts would be expected to be 

spatially extensive, but they are expected to only temporarily alter the overall 

status of GOM pinnacle and low-relief feature communities such that long-term 

recovery to pre-impact levels is likely.

• Major – Impacts to pinnacle and low-relief feature communities detectably cause 

substantial, population-level changes in species composition, community 

structure, and/or ecological functioning. These impacts would be expected to be 

spatially extensive and to noticeably alter the overall status of GOM pinnacle and 
Description of the Affected Environment and Impact Analysis 4-187

low-relief feature communities such that long-term recovery to pre-impact levels 

is unlikely.

The primary relevant, reasonably foreseeable impacts of routine activities and accidental 

events to live bottom habitats described in this chapter can be grouped into the following three 

general categories:

(1) bottom-disturbing activities (routine and accidental);

(2) drilling-related sediment and waste discharges (routine and accidental); and

(3) oil spills (accidental).

These impacts are analyzed in detail under the “Routine Activities” and “Accidental Events” 

sections below. Cumulative impacts were also considered in two steps: cumulative impacts 

resulting from OCS oil- and gas-related activities and impacts resulting from non-OCS oil- and gasrelated activities.

Some impact-producing factors relevant to pinnacle and low-relief feature communities are 

analyzed in detail in other chapters and need only be briefly summarized here. For example, 

Chapter 4.7 (Fishes and Invertebrate Resources) details impacts from anthropogenic noise. Note 

that despite the growing body of information available for fishes, there is comparatively little 

information available on sound detection and sound-mediated behaviors for marine invertebrates. 

That said, the overall impacts on pinnacle and low-relief feature communities from anthropogenic 

noise are expected to be negligible. Chapter 4.7 also details the impacts of routine activities and 

the cumulative impacts from OCS oil- and gas-related infrastructure presence, subsequent removal, 

and/or conversion to artificial reefs. While the total contribution of OCS infrastructure is still only a 

small percentage of natural hard bottoms (Gallaway et al., 2009) and is projected to further decrease 

throughout the period covered by this analysis (Chapter 3.3.1.5), the presence, removal, and/or 

conversion of artificial hard substrates colonized by sessile invertebrates are likely to result in 

localized community changes, such as changes in species diversity in an area (Schroeder and Love, 

2004). While individual presence, removal, or conversion actions at specific locations do not cause 

more than negligible impacts when considered against the broader scope of this analysis, when the 

sum of such actions are considered cumulatively for all planning areas and over 50 years, such 

impacts could be greater for individual species. This is because select species commonly 

associated with OCS oil and gas platforms could be noticeably influenced over time by the overall 

presence (or removal) of OCS infrastructure. For example, a particular hermatypic coral species’ 

Gulfwide spatial distribution may shift over time because of the presence or removal of structures in 

otherwise soft bottom-dominated areas. Such a change (were it to occur) could be considered a 

moderate level impact (for that species) if it represented a detectable change in the species’ spatial 

distribution; such a range shift might have potential long-term effects related to dispersal and genetic 

connectivity to other populations of that species. Such potential impacts are not necessarily either 

positive or negative; that would be dependent on the species and a number of complex ecological 

factors. Some evidence of these types of changes (in particular, range expansion) has been 
4-188 Gulf of Mexico Multisale EIS

documented for some shallow-water hermatypic species (Sammarco et al., 2012). More peerreviewed literature about this topic is available for fish resources, as detailed in Chapter 4.7 (Fishes 

and Invertebrate Resources).

Several additional impact-producing factors described in Chapters 3.1 and 3.2 were 

evaluated for potential impacts on these live bottom communities. These impact-producing factors 

were not carried forward for full analysis because any potential effects were judged to be either not 

reasonably foreseeable or having such a miniscule impact that they would not rise to the level of 

negligible impact. These impact-producing factors include surface oil-spill response efforts (refer to 

Chapter 4.6.1, Topographic Features), impacts from G&G activities other than bottom disturbance 

(bottom disturbance is covered below), and potential impacts from a sinking vessel. A sinking vessel 

settling on a live bottom community is not a reasonably foreseeable impact-producing factor. Even if 

such an incident did occur, it would not have a population-level impact despite likely crushing or 

smothering live bottom organisms in the area of direct contact.

Some potential impact-producing factors are already regulated by other Federal agencies 

and/or international treaties. For example, the discharge of marine debris is subject to a number of 

laws and treaties. These include the Marine Debris Research, Prevention, and Reduction Act; the 

Marine Plastic Pollution Research and Control Act; and the MARPOL-Annex V Treaty. Regulation 

and enforcement of these laws is conducted by a number of agencies such as the U.S. 

Environmental Protection Agency, NOAA, and the U.S. Coast Guard. To further reduce potential 

impacts, the BSEE provides guidance on marine debris training of all OCS personnel through the 

“Marine Trash and Debris Awareness and Elimination” NTL (NTL 2015-BSEE-G03). Historically, this 

NTL has been made a binding part of leases through application of the Protected Species 

Stipulation. This NTL instructs OCS operators to post informational placards that outline the legal 

consequences and potential ecological harm of discharging marine debris. This NTL also states that 

OCS workers should complete annual marine debris prevention training; operators are also 

instructed to develop a certification process for the completion of this training by their workers. 

These various laws, regulations, and NTL would likely minimize any potential damage to live bottom

resources from the discharge of marine debris related to OCS oil- and gas-related operations. 

Nonetheless, some accidental release of marine debris is still likely to occur as a result of OCS oiland gas-related operations and could theoretically have limited effects on live bottom organisms 

(e.g., physical damage caused by strong currents pushing debris into fragile organisms or ingestion 

of plastics by invertebrates). However, the amount of debris in question would not suffice to cause 

even negligible impacts when considered at the scale of the overall population of live bottom 

communities in the GOM. One possible exception would be frequent accidental losses of very large 

items such as pipeline segments with the potential to crush or smother live bottoms. That impactproducing factor is briefly discussed under “Bottom-Disturbing Activities” in the “Accidental Events” 

section below, even though any such losses are expected to be very rare. In all cases, the likelihood 

of spatial overlap with debris from OCS vessels or infrastructure is inherently small due to the 

relatively rare and patchy distribution of live bottom communities in the GOM, particularly in areas of 

the western and northern GOM, which have the greatest amount of OCS oil- and gas-related

operations.
Description of the Affected Environment and Impact Analysis 4-189

Another potential impact-producing factor that is largely governed by (and potential impacts 

reduced by) external regulations is the potential presence of toxins in drilling muds and cuttings 

and/or produced waters. Because of the regulations issued by the USEPA and/or international 

treaties designed to keep toxins below harmful levels, hazardous levels of toxins are generally not 

expected to reach live bottom communities. Nonetheless, potential impacts from toxins are briefly 

discussed in the “Routine Activities” section below.

Historical Protections of Pinnacle and Low-Relief Features

Protective measures have been developed over time based on the nature and sensitivity of 

various live bottom habitats and their associated communities, as understood from decades of 

BOEM-funded and other environmental studies. These protections were developed into stipulations

historically applied to OCS leases in areas with known concentrations of live bottom features. The 

Pinnacle Trend is a specific series of high- and low-relief hard/live bottom features occurring just 

east of the Mississippi River. BOEM has consistently applied the Live Bottom (Pinnacle Trend) 

Stipulation to 74 OCS lease blocks covering this area (which is a required mitigation as a result of 

the Five-Year Program’s Record of Decision). The CPA blocks directly adjacent to low-relief blocks 

are included in a proposed action and some of the alternatives; therefore, the potential impacts of 

routine activities and accidental events originating in those adjoining blocks are analyzed here. A full 

list of the proposed stipulation blocks can be found in Appendix D. 

Live bottom habitats are found outside the blocks where the Topographic Features and Live 

Bottom Stipulations have been historically applied (which is a required mitigation as a result of the 

Five-Year Program’s Record of Decision). Such habitats are not specifically included in those 

stipulations but are still routinely given protections during NEPA reviews of site-specific development 

plans, as described in NTL 2009-G39, “Biologically-Sensitive Underwater Features and Areas.” That 

NTL provides information and consolidates guidance to help operators understand BOEM’s 

requirements related to sensitive benthic habitats.

Lessees must provide site-specific seafloor survey data and interpretive information 

(including about hard bottom features) with each EP, DOCD, and DPP. Site-specific NEPA reviews 

are conducted on these plans by BOEM’s subject-matter experts on a case-by-case basis to 

determine whether a proposed operation could impact a live bottom feature. If an impact is judged 

likely based on site-specific information derived from BOEM’s studies/databases, other published 

research, geohazard survey data, or another creditable source, the operator may be required to 

distance/relocate the proposed operation or undertake other mitigations to prevent an impact. This 

analysis assumes continuation of the protective measures outlined in NTL 2009-G39, as they are 

routinely applied (when and where appropriate) during all site-specific plan reviews. The Live 

Bottom Stipulation is applied to individual lease sales at the discretion of the Secretary and has been 

consistently applied to the same lease blocks for decades. The types of potential impacts to live 

bottom communities described in this chapter would become more likely and more severe without 

the continued application of these stipulations.
4-190 Gulf of Mexico Multisale EIS

4.6.2.1 Description of the Affected Environment

The terms live bottom and hard bottom are often used interchangeably, but they are actually 

distinct since it is possible to have hard bottom that is not live bottom. Hard substrates can form 

crusts, pavements, pinnacles, ledges, outcrops, and other reefal features (Jenkins, 2011). These 

harder substrates may or may not be covered by a thin veneer of muddy or sandy sediments that 

can be deposited and removed over time by currents and storms. Hard substrates with the lowest 

vertical relief are the most likely to be routinely buried and exposed. Encrusting algae and sessile 

invertebrates regularly attach to and cover exposed hard substrates, creating live bottoms. For the 

purposes of the Live Bottom Stipulation, “live bottom areas” have been defined as communities or 

areas that contain biological assemblages consisting of sessile invertebrates such as sea fans, sea 

whips, hydroids, anemones, ascidians, sponges, bryozoans, or corals living upon and attached to 

naturally occurring hard or rocky formations with rough, broken, or smooth topography; or areas 

whose lithotope (substrate type) favors the accumulation of turtles, fishes, and other fauna.

Distribution of Hard/Live Bottoms in the Gulf of Mexico

The distribution of hard bottoms (and associated live bottom communities) in the GOM is not 

fully known, due in part to the patchy and ephemeral (temporary) nature of hard bottoms that do not 

have sufficient vertical relief to avoid intermittent sediment burial (Parker et al., 1983; Jenkins, 2011; 

Simmons et al., 2014; Jaap, 2015). Although accurate quantification is challenging and can quickly 

become outdated, Parker et al. (1983) illustrates a reasonable overall proportion and distribution of 

hard bottoms in U.S. portions of the GOM. The study extrapolated from 732 visual sampling stations 

to roughly approximate the amount of hard bottom habitat in a band of relatively shallow waters 

(18-91 m; 59-299 ft), estimating that about 94 percent (44,946 km2

; 17,354 mi2) of the total lies 

between Key West and Pensacola, Florida, on the broad West Florida Shelf, and only about 

6 percent (2,780 km2

; 1,073 mi2) lies between Pensacola, Florida, and the Rio Grande River, where 

the continental shelf break is closer to shore. More recently, Jenkins (2011) interpolated a Gulfwide 

estimate of dominant surficial seafloor sediments.

Beyond direct sampling and visual observations, an evolving variety of geophysical 

techniques such as sidescan- and multibeam echo sounder-sonar (Hine et al., 2008; Mueller et al., 

2014) and 3D seismic (USDOI, BOEM, 2015b; Chapter 4.4, Deepwater Benthic Communities) can 

also be used to estimate and map the distribution of hard bottom habitats. In the eastern GOM, far 

from the proposed EPA lease sale area and in parts of the EPA currently under a lease moratorium, 

there are several areas (including the Florida Middle Grounds, Madison-Swanson Marine Reserve, 

Steamboat Lumps, the Dry Tortugas Ecological Reserves, and Pulley Ridge, as shown in Figure 

4-17) containing high concentrations of low-relief live bottom habitat. These and other areas have 

been designated by NMFS and GMFMC as marine reserves and/or EFH Habitat Areas of Particular 

Concern in recognition of the high ecological and socioeconomic (i.e., fisheries) value of live bottom 

habitat (Simmons et al., 2014; Figure 4-17). Designation is intended to encourage additional 

research and (in some but not all cases) implement fisheries management measures such as 

restrictions on gear types (Simmons et al., 2014). However, HAPC designation does not have direct 

bearing on nonfishing activities such as those regulated by BOEM. BOEM does consult with NMFS 
Description of the Affected Environment and Impact Analysis 4-191

on EFH and HAPCs, including the above-named areas (Essential Fish Habitat Assessment white 

paper, USDOI, BOEM, 2016d).

Live Bottom Ecology

Live bottom communities are controlled by interconnected abiotic and biotic factors (Brooks, 

1991; Weaver et al., 2002; Jaap, 2015). Physical conditions (e.g., light, sedimentation/turbidity, 

substrate type, temperature, salinity, prevailing currents, and the frequency and intensity of severe 

weather events) affect biological variables such as larval transport, settlement, and growth. For 

example, Lugo-Fernández et al. (2001) reported blockage of coral larval dispersal from the Flower 

Garden Bank area to the eastern GOM by the Mississippi River plume. In addition, biological 

controls, such as predation and trophic interactions, can affect epibenthic community development 

and disturbance response. The relative importance of each controlling factor varies for different 

types of epibenthos (Jaap, 2015).

A persistent nepheloid layer (a layer of suspended sediment-laden water of variable density 

and vertical size that persists above the seafloor) can be a controlling factor for live bottom species 

sensitive to turbidity (Rezak et al., 1990), exerting an influence on their bathymetric and geographic 

distribution, and thus is also relevant to impact-producing factors of some OCS oil- and gas-related 

activities. This layer reduces the light reaching hard bottoms, resulting in decreased species 

richness and abundance below 262 ft (80 m) (Dennis and Bright, 1988; Rezak et al., 1990). Some 

studies suggest that the Mississippi River plume influences the distribution and abundance of sessile 

invertebrates within 43 mi (70 km) of the river delta and may affect turbidity and sedimentation 

throughout the Pinnacle Trend (Gittings et al., 1992a; CSA and GERG, 2001). Nepheloid layers are 

less frequent in the eastern GOM, but they can occur when the Mississippi River plume and 

upwelling affect the area (CSA and GERG, 2001).

Large, shallow-water coral reefs created via biogenic deposition of calcium carbonate over 

time by hermatypic coral species (refer to Schumacher and Zibrowius [1985] for more information 

about theoretical and practical definitions of “hermatypic”) are present only at the southern end of the 

EPA and on a few topographic features in the WPA and CPA (refer to Chapter 4.6.1, Topographic 

Features, for the impact analysis). While the general public often thinks of such biogenic coral reefs 

as the only natural habitat for corals, Jaap (2015) illustrates that, for most of their geological history, 

corals have existed in less elaborate epibenthic communities that are not built upon large biogenic 

reefs (Veron, 1995 and 2000). These types of corals and epibenthic communities are the focus of 

this chapter on pinnacles and low-relief features.

The Pinnacle Trend Area

Physical Characteristics

The Pinnacle Trend is an approximately 64 x 16 mi (103 x 26 km) area in water depths of 

about 200-650 ft (60-200 m). It is in the northeastern portion of the CPA portion of the proposed 
4-192 Gulf of Mexico Multisale EIS

lease sale area at the outer edge of the Mississippi-Alabama shelf, between the Mississippi River 

and De Soto Canyon (Figures 4-17 and 4-19A).

Live bottoms within the Pinnacle Trend features consist of both high-relief outcroppings at 

the edge of the Mississippi-Alabama Shelf and low-relief hard bottoms on the inner and middle shelf. 

BOEM has sponsored numerous studies providing information about these features (Brooks, 1991; 

CSA, 1992; Thompson et al., 1999; CSA and GERG, 2001). A 2002 bathymetric survey by the 

USGS (Gardner et al., 2002) provided high-quality seafloor imagery that has become the baseline 

for this area (Figure 4-19B).

The eastern part of the Pinnacle Trend is covered with a thin, well-sorted layer of fine- to 

medium-grained quartzose sand originating from eastern continental rivers. The western portion is 

covered with fine silts, sands, and clays deposited by the Mississippi River (CSA, 1992). The linear 

orientation and distribution of some features correspond with depth contours and may represent 

historic shorelines and drowned calcareous biogenic reefs that developed prior to the most recent 

sea-level rise (Ludwick and Walton, 1957; Sager et al., 1992; Thompson et al., 1999).

The high-relief features are complex in shape and structure (e.g., Figure 4-19A-C) and 

provide varied zones of microhabitat for attached organisms. High-relief features consist of 

pinnacles, flat-top reefs, reef-like mounds, patch reefs, and ridges and scarps. Tall spire-like 

mounds are the historical “pinnacles” for which the region is named. The pinnacles rise up to 66 ft 

(20 m) in height and can be over 1,640 ft (500 m) in diameter (Thompson et al., 1999; Brooks, 

1991). Other features in this area are smaller and have less vertical relief, but they are more 

numerous. Low-relief features include fields of small seafloor mounds that rise only a meter or two 

above the seafloor but still provide hard surfaces for attached epifauna. Fields of shallow 

depressions about 3-20 ft (1-6 m) across also add habitat complexity to the overall character of the 

Pinnacle Trend area.
Description of the Affected Environment and Impact Analysis 4-193

Figure 4-19. General Location of the Pinnacle Trend (A), Multibeam Bathymetry 

and Named Reef Areas (B), and an Exaggerated Vertical Relief 

Profile of Rough Tongue Reef (C). (Figure parts were excerpted and 

rearranged from Gardner et al., 2002).

Ecology of Live Bottom Communities in the Pinnacle Trend

The substantial amount of hard substrate in the Pinnacle Trend supports colonization by 

large numbers of suspension-feeding invertebrates, including octocorals, black corals, and sponges, 

and over 70 species of fish (Weaver et al., 2002). The Pinnacle Trend features are composed of 

carbonate reef material (Ludwick and Walton, 1957) and vary in shape, size, vertical relief, and 

overall complexity. These physical characteristics affect the composition (e.g., biodiversity, density, 
4-194 Gulf of Mexico Multisale EIS

etc.) of the community associated with the substrate. Generally, the more complex the topographic 

shape of the substrate, the greater the variety of habitats for organisms and thus greater abundance 

and diversity of organisms.

Assemblages of coralline algae, sponges, octocorals, crinoids, and bryozoans are present at 

the tops of the shallowest features in water depths of less than 230 ft (70 m) (CSA, 1992). On the 

deeper features, as well as along the sides of the shallower pinnacles, ahermatypic corals may be 

locally abundant, along with octocorals, crinoids, and basket stars. The diversity and abundance of 

the associated species appear to be related to the size and complexity of the features, with the 

lower-relief outcrops typically having lower faunal densities and higher relief features having more 

diverse faunal communities (Gittings et al., 1992a; Thompson et al., 1999).

Low-Relief Live Bottoms

Outside of the Pinnacle Trend, low-relief live bottom features can and do occur in isolated 

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

substrate and other physical conditions (depth, turbidity, etc.) allow for epibenthic community 

development (Rezak et al., 1990). However, they are primarily known to be present in some 

locations on the Mississippi-Alabama Shelf and many more locations on the West Florida Shelf 

(Figure 4-17), far east of the proposed EPA lease sale area. None of the blocks with known 

concentrations of live bottom low-relief habitat are expected to be offered for lease; however, several 

live bottom low-relief areas are adjacent to blocks that would be offered for lease under a proposed 

action and could potentially be affected by impacts of routine activities and accidental events. 

Therefore, an analysis of the potential impacts is included in this Multisale EIS.

Ecology of Inner- and Middle-Shelf Live Bottoms of the Mississippi-Alabama Shelf

These nearshore, hard bottom areas are located in 60-130 ft (18-40 m) of water. A finegrained quartz sand sheet covers most of the Mississippi-Alabama Shelf; however, numerous hard 

bottoms that are formed of sedimentary rock occur off the Mississippi River Delta and seaward of the 

Chandeleur Islands (Schroeder, 2000). These features include isolated low-relief, reef-like 

structures; rubble fields; low-relief flat rocks; limestone ledges; rocky outcrops off Mobile Bay; and 

clustered reefs (Schroeder et al., 1988; Schroeder, 2000). Hard bottom features on the MississippiAlabama-Florida Shelf typically provide reef habitat for tropical organisms, including sessile epifauna 

(i.e., soft corals, ahermatypic hard corals, sponges, bryozoans, and crinoids) and fish.

Various live bottom areas of the Mississippi-Alabama Shelf have been described in literature 

(Shipp and Hopkins, 1978, Schroeder et al., 1988; Schroeder et al., 1989, Brooks, 1991). These 

areas support a number of foundational species (including hard and soft corals, coralline algaes, and 

sponges) that are associated with larger, diverse communities of mobile invertebrates and fishes.
Description of the Affected Environment and Impact Analysis 4-195

Ecology of Inner- and Middle-Shelf Live Bottoms of the West Florida Shelf

The majority of low-relief live bottom habitats in the GOM are found on the West Florida 

Shelf. The shelf is a relatively flat table of carbonate limestone that is largely covered with carbonate 

sand sheets. BOEM has designated blocks on the West Florida Shelf out to the 100-m (328-ft) 

isobath as Live Bottom (Low-Relief) Stipulation blocks (Figure 4-17) because live bottom 

communities are widely scattered across the West Florida Shelf on limestone ledges and outcrops 

(Jaap, 2015). In many places, the sand frequently shifts due to seasonal storms, occasionally 

uncovering patches of hard bottom. The nepheloid layer found throughout much of the northern 

CPA is not present to the same degree on the West Florida Shelf.

In addition to the smaller, widely distributed low-relief hard bottoms, there are also areas with 

permanently exposed, higher relief hard bottoms. In the southeastern portion of the GOM, shallowwater hermatypic corals are common throughout the Florida Keys reef tract, the Dry Tortugas, and 

Pulley Ridge (Jaap, 2015). To the north along the West Florida Shelf are several other important 

areas recognized by NMFS/GMFMC (Simmons et al., 2014). Some of these areas are thought to be 

relic reef formations that were “drowned” with historic sea-level rises.

Various sessile fauna and flora develop on exposed surfaces of low-relief hard substrates 

(Jaap, 2015). Some fauna, such as gorgonian soft corals, are flexible and tall enough to survive 

partial sediment burial. Many of the formations have deep reef communities with soft corals, black 

corals, sponges, sea whips/sea fans, anemones, and associated mobile echinoderms and 

crustaceans. Habitats that are sufficiently close to the water surface can support some hermatypic 

corals. Scleractinian and milleporian corals are common on rocky outcrops throughout the eastern 

GOM (Jaap, 2015).

Consultations

In 2014, 20 new coral species were listed as “threatened” under the ESA; all but 7 of these 

are found only in Indo-Pacific waters (Federal Register, 2014b). Three of the new species and two 

others that were previously listed (elkhorn and staghorn) are found in shallow waters of the GOM. 

Some are found on a few topographic features in the WPA/CPA and others in the Dry Tortugas and 

Florida reef tract. These coral species are further described in Chapter 4.9.5. The OCS lease 

blocks in the EPA near areas containing these species are not being offered in a proposed lease 

sale due to the current leasing moratorium and are therefore too distant to be reasonably affected by 

routine activities or accidental events occurring in leased areas. Currently, only staghorn and 

elkhorn coral have had critical habitat areas defined off the Florida Keys and Florida reef tract, 

neither of which are located in the proposed lease sale area. For ESA-listed coral found in the 

proposed lease sale area (specifically, on portions of the Flower Garden Banks) where accidental 

impacts might be possible, these coral species would be expected to experience the same types of 

impact-producing factors as other live bottom organisms. However, due to their relatively low 

population sizes, any impacts from accidental events on ESA-listed corals would have a magnified 

effect on each of those populations. BOEM consults on listed corals as part of the Section 7 
4-196 Gulf of Mexico Multisale EIS

consultation with NMFS. Adherence to recommendations resulting from this consultation and 

application of the Live Bottom Stipulation should prevent or minimize any impacts to these species.

4.6.2.2 Environmental Consequences

4.6.2.2.1 Routine Activities

A number of routine OCS oil- and gas-related impact-producing factors may cause adverse 

impacts on pinnacle and low-relief feature communities. As noted above, some factors with minimal 

impacts are presented in greater detail in other chapters and are not repeated here. The potential 

routine impact-producing factors on pinnacle and low-relief feature communities analyzed here are 

grouped into two main categories having similar impacts: (1) bottom-disturbing activities (e.g., 

anchoring, infrastructure emplacement and removal, and core sampling); and (2) drilling-related 

sediment and waste discharges (e.g., drilling muds and cuttings, and produced waters). These 

impact-producing factors have the potential to damage pinnacle and low-relief feature communities if 

not sufficiently distanced via mitigations. 

Bottom-Disturbing Activities

Bottom-disturbing activities can be described as any activities that result in the physical 

disturbance of the seafloor during the exploration, production, or decommissioning phase of OCS oiland gas-related operations. Anchoring, operational wastes produced during drilling, trenching, pipelaying, and structure emplacement and removal are examples of OCS oil- and gas-related activities 

that disturb the seafloor (refer to Chapter 3.1). The spatial extent of the seafloor disturbance and 

the magnitude of the effect on benthic organisms would depend on the specific activity, local 

environmental conditions (e.g., currents, water depth, etc.), and species-specific behaviors and 

habitat preferences.

Turbidity from suspended sediments, along with sediment displacement resulting from 

routine, bottom-disturbing OCS oil- and gas-related activities generally have localized effects. In 

general, impacts to pinnacle and low-relief feature communities could include any or all of the 

following: reduced settlement and growth due to loss of available hard substrate; inhibited feeding 

leading to reduced reproductive fitness; and mortality of individuals (e.g., coral polyps) and groups 

(e.g., a coral colony). Reductions in overall biological cover could have secondary ecological effects 

on organisms that were using the complex structural microhabitats. Some mobile invertebrates 

(e.g., star fish) are expected to be able to move to avoid the heaviest sedimentation and highest 

suspended sediment loads within 33 ft (10 m) of a disturbance, while sessile invertebrates (e.g., 

corals) cannot. Both sessile and mobile invertebrate species adapted to living in turbid 

environments, such as those commonly found in the persistent nepheloid layer or otherwise adapted 

to occasional sediment inundation, may be less affected by increased turbidity. Such organisms 

may be adapted to remove some covering sediment via tentacle motion and mucus secretion (Shinn 

et al., 1980; Hudson and Robbin, 1980). Other species that typically inhabit less turbid waters would 

suffer greater impacts (Rogers, 1990; Gittings et al., 1992a). For example, zooxanthellate coral 

species are dependent on a continuous, unobscured light source to support the symbiotic 
Description of the Affected Environment and Impact Analysis 4-197

photosynthetic algae (zooxanthellae) and may suffer coral bleaching if the water column becomes 

overly turbid. Solitary octocorals and gorgonians are generally more tolerant of sedimentation, partly 

because they grow tall and are flexible, reducing sediment accumulation and allowing for easier 

removal (Marszalek, 1981; Torres et al., 2001; Gittings et al., 1992a).

In addition to drilling activities, the process of installing and removing OCS oil- and gasrelated infrastructure (i.e., pipelines, platforms, and subsea systems including cables) also has the 

potential to displace large volumes of sediment. The resulting localized increases in turbidity and 

sedimentation would have the same indirect impacts as those caused by drilling-related sediment 

discharges. 

The OCS oil- and gas-related infrastructure/equipment also has the potential to damage or 

kill benthic organisms should the equipment itself make direct contact. Any object placed on or 

through a live bottom feature can cause partial or complete breakage, crushing, or smothering. In 

addition to mortality, there could be any or all of the potential sublethal impacts already described 

above in relation to sedimentation. The severity of impacts from direct physical contact would vary 

in direct proportion to the surface area and mass of the specific equipment. For example, the 

placement of a large bottom-founded platform on a live bottom would have a much greater impact 

than the placement of a small umbilical cable.

Similarly, anchor damage is one of the greatest threats to the biota of the offshore banks in 

the GOM (Rezak and Bright, 1979; Rezak et al., 1985; Gittings et al., 1992a; Hudson et al., 1982). 

Anchors may break, fragment, or overturn corals, sponges, and other benthic organisms, and the 

anchor chain or cable may drag across and shear organisms off the substrate (Dinsdale and 

Harriott, 2004). This would result in negative consequences ranging from increased stress to 

mortality (Dinsdale and Harriott, 2004). The impact of dragging an anchor across a live bottom 

would depend on the distance and duration of bottom contact, but it could be considerable due to the 

forces involved. Dragged anchors often leave seafloor scars noticeable on sidescan-sonar imagery 

years later. Damage to a coral community may take 10 or more years to recover (Fucik et al., 1984; 

Rogers and Garrison, 2001).

Drilling-Related Sediment and Waste Discharges

Drilling of new wells is one of the activities with the greatest impact potential, due to the 

associated sedimentation/turbidity caused by the drilling process and from the release of drilling 

cuttings and discharges. As noted in Chapter 3, drilling an exploratory well produces approximately 

2,000 metric tons of combined drilling fluid and cuttings, though the total mass may vary widely for 

different wells (Neff, 2005). Cuttings discharged at the surface tend to disperse in the water column 

and are distributed at low concentrations (CSA, 2004a). In deep water, the majority of cuttings 

discharged at the sea surface are likely to be deposited within 250 m (820 ft) of the well (CSA, 

2006). Cuttings shunted to the seafloor forms piles concentrated within a smaller area than when 

sediments are discharged at the sea surface (Neff, 2005).
4-198 Gulf of Mexico Multisale EIS

Apart from turbidity and sedimentation, the chemical content of drilling muds and cuttings, 

and to a lesser extent produced waters, is another potential impact-producing factor since these may 

contain hydrocarbons, trace metals including heavy metals, elemental sulfur, and radionuclides 

(Kendall and Rainey, 1991; Trefry et al., 1995). Substances containing heavy metals and other 

potentially toxic compounds would have the potential to be moderately toxic to live bottom

organisms, but only if they were to come into contact in undiluted strengths (CSA, 2004a). Although 

the literature has not reported impacts to corals as a result of exposure to contaminants in cuttings, 

infauna have shown effects at distances <100 m (<330 ft) from the discharge. These include 

reduced reproductive fitness, altered populations, and acute toxicity (Montagna and Harper, 1996; 

Carr et al., 1996; Kennicutt et al., 1996; Hart et al., 1989; Chapman et al., 1991; CSA, 2004a). 

Because of BOEM’s distancing requirements for new wells, contact with concentrated (and 

potentially harmful) levels of any such toxins is not expected. Produced waters (refer to Chapter 

3.1.5.1.1 for more detail) are rapidly diluted with distance, and impacts are generally only observed 

within very close proximity of the discharge point (Gittings et al., 1992a; Neff, 2005). In addition to 

the protection offered by BOEM’s distancing requirements, releases of toxic discharges are 

regulated by the USEPA through the issuance of NPDES permits. Adherence to NPDES permit 

requirements would help ensure that water quality is maintained at nontoxic levels.

As further detailed in other chapters, explosive severance methods used during 

decommissioning activities could result in damage or death to any organisms within the vicinity of 

the blast or associated sediment plume, although long-term turbidity is not expected from platform 

removal operations. The shockwave from the blast could also damage or destroy the underlying 

hard substrates required to support live bottoms. The BSEE Interim Policy Document 2013-07, 

“Rigs-to-Reefs Policy,” specifies that the use of explosive severance methods will not be approved if 

analysis determines they would cause harm to established artificial reef sites and/or natural live 

bottoms.

Potential impacts resulting from all of the above routine activities are mitigated through the 

Live Bottom Stipulation and the protective measures summarized above and detailed in NTL 2009-

G39. The site-specific survey information and distancing requirements described in NTL 2009-G39 

would allow BOEM to identify and protect live bottom features from harm by proposed OCS oil- and 

gas-related activities during postlease reviews. If those protective measures are applied to identified 

pinnacle and low-relief feature communities as expected, at the scope of this analysis, impacts of 

routine activities would be expected to be negligible. These protective measures are now a 

required mitigation as a result of the Five-Year Program’s Record of Decision.

Without adherence to the requirements of the stipulation and external regulatory restrictions 

on discharges, impacts to pinnacle and low-relief feature communities from the above routine 

activities could rise to minor, moderate, or even major, depending on the number and locations of 

specific activities. The highest impact levels are possible in the improbable (but theoretically 

possible) case that a large number of routine activity disturbances were to physically impact a large 

number of live bottom habitats. Even without mitigations, the likelihood is very low that a large 

number of OCS oil- and gas-related activities would occur in close proximity because the hard 
Description of the Affected Environment and Impact Analysis 4-199

substrate habitats supporting pinnacle and low-relief feature communities are patchily distributed 

throughout the GOM and are relatively rare compared with soft bottom substrates. But this 

possibility cannot be definitively ruled out without knowing the precise spatial distribution of both 

future OCS oil- and gas-related activities and live bottom communities.

4.6.2.2.2 Accidental Events

The primary accidental impact-producing factors on pinnacle and low-relief feature 

communities analyzed here are grouped into two categories: (1) bottom-disturbing activities (e.g., 

anchoring and infrastructure emplacement and removal); and (2) oil spills (surface and subsurface) 

and associated cleanup responses. These impact-producing factors have the potential to damage 

pinnacle and low-relief feature communities if not sufficiently distanced or otherwise mitigated.

Bottom-Disturbing Activities

Impacts resulting from bottom-disturbing activities were detailed under “Routine Activities” 

and are largely the same for accidental events. There are only slight differencesrelated to 

mechanisms and potential severity. The primary, accidental bottom-disturbing activity is the 

inadvertent deposition or placement of equipment on live bottoms. Accidental loss of equipment 

could occur during transfer operations between vessels and platforms, during vessel transit, during 

an “on deck” accident, as a consequence of a severe storm, or if a structure, drill, or anchor is 

unintentionally placed in the wrong location during operations. During routine operations, distancing 

mitigations offer some protections against these types of impact, but those protections do not apply 

to accidents, other than to reduce the likelihood of routine activities occurring in pinnacle and lowrelief feature areas in the first place. Any object placed on or through a pinnacle and low-relief 

feature can cause partial or complete breakage, crushing, or smothering of both substrate and 

organisms, and/or could cause increased sedimentation as equipment disturbs the seafloor. In 

addition to mortality, pinnacle and low-relief feature communities could experience any or all of the 

potential sublethal impacts already described in the “Routine Activities” section above. The severity 

of impacts from direct physical contact would vary in direct proportion to the surface area and mass 

of the specific equipment. Given the relative rarity of pinnacle and low-relief features and 

communities in the GOM, impacts from accidental bottom-disturbing equipment are expected to be 

infrequent and highly localized, with the likelihood of accidental contact further reduced by the 

expected distancing mitigations. However, because of the unplanned and potentially uncontrolled 

nature of accidental bottom-disturbing events, there exists greater uncertainty about their potential 

impact severity than exists for planned routine activities, and there is the potential for a minor level 

impact under the right combination of conditions. Therefore, at the scale of this analysis, impacts 

from accidental bottom-disturbing activity to pinnacle and low-relief features and associated 

communities could range from negligible to minor, depending on the overall frequency and severity 

of the accidental events.

Without the protective measures provided by the Live Bottom Stipulation (which is a required 

mitigation as a result of the Five-Year Program’s Record of Decision) and by postlease reviews and 

distancing, the potential impacts of accidental bottom disturbances could rise to moderate or even 
4-200 Gulf of Mexico Multisale EIS

major levels in the improbable (but theoretically possible) case that a large number of accidental 

disturbances were to physically impact a large number of pinnacle trend and low-relief features and 

if community-level impacts can be clearly distinguished from a natural variation. Even without 

mitigations, the likelihood is very low that a large number of OCS oil- and gas-related activities would 

occur in close proximity to the relatively rare hard substrate habitats supporting the communities, but 

this possibility cannot be definitively ruled out without knowing the precise spatial distribution of both 

future OCS oil- and gas-related activities and the features/communities.

Oil Spills and Associated Impacts

Oil spills, historic trends, the characteristics of oil, and factors affecting the fate of oil 

released into the marine environment are discussed in detail in Chapter 3.2.1, and the potential 

effects on water quality are analyzed in Chapter 4.2 (Water Quality). For information on impacts 

specifically resulting from a catastrophic oil spill (beyond the scope of this analysis), refer to the 

Catastrophic Spill Events Analysis white paper (USDOI, BOEM, 2017).

Impacts related to an accidental release of oil or other contaminants could adversely affect 

pinnacle and low-relief feature communities. Potential impacts related to an accidental spill would 

depend on the combination of these various components: surface oil; subsurface oil; chemical 

dispersants and dispersed oil; sedimented oil (oil adsorbed to sediment particles, also known as 

“marine snow”); sedimentation caused by a loss of well control; and certain spill-response activities. 

Adherence to well-distancing requirements should serve to reduce such impacts.

Biological impacts resulting from exposure to accidentally released oil droplets and/or 

chemical dispersants are anticipated to be mostly sublethal. Sublethal impacts that may occur to 

exposed corals and similar benthic invertebrates may include reduced feeding, reduced 

photosynthesis, reduced reproduction and growth, physical tissue damage, and altered behavior. 

For example, short-term (24 hours) sublethal responses of one coral species included mesenterial 

filament extrusion, extreme tissue contraction, tentacle retraction, and localized tissue rupture after 

exposure to dispersed oil at a concentration of 20 ppm (Knap et al., 1983; Wyers et al., 1986). It is 

important to note that, generally, laboratory experimental concentrations are designed to discover 

toxicity thresholds (e.g., DeLeo et al., 2015) that exceed probable exposure concentrations in the 

field.

Oil spills originating at the surface, such as from a vessel or platform, have some potential to 

impact pinnacle and low-relief feature communities. The depth of the feature communities helps to 

buffer and protect them from most surface spills because their crests are generally deeper than the 

physical mixing ability of surface oil (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and 

Chan, 2002; Thompson et al., 1999; Schroeder, 2000). Oil becomes diluted as it physically mixes 

with the surrounding water column. The shallowest known concentrations of pinnacle and low-relief 

features occur in the Live Bottom (Low Relief) Stipulation blocks within the EPA (Figure 4-17), and 

none of these blocks are expected to be offered for lease since they are under a Congressional 

leasing moratorium through 2022. In the Pinnacle Trend area, the largest features rise to within 
Description of the Affected Environment and Impact Analysis 4-201

40 m (130 ft) of the sea surface. In very unusual conditions, surface oil and/or surface dispersant

could contact some of the shallower Pinnacle Trend features. Silva et al. (2015) documented acute 

lethal and sublethal impacts to gorgonians on Pinnacle Trend features caused by large amounts of 

Deepwater Horizon-sourced surface oil. A large volume of oil/dispersant mixture was submerged by 

unusually strong wave action associated with a tropical storm that passed directly over the oil. As a 

result, sizable amounts of the relatively undiluted oil/dispersant reached live bottom features. This 

contact, though demonstrably possible, required an unusual combination of atypical conditions, 

making it generally unlikely outside of a catastrophic spill situation, which is not part of a proposed 

action and not likely expected to occur.

In a subsurface spill or loss of well control situation, it is expected that the majority of 

released oil would rise quickly to the surface due the characteristics of northern GOM oil reserves, 

meaning most impacts would be similar to a surface-originating spill. However, if an oil spill/loss of 

well control occurs at great depths and released oil is subjected to higher water pressures, some oil 

droplets may emulsify and become entrained deep in the water column (Boehm and Fiest, 1982), 

creating a subsurface plume (Adcroft et al., 2010). In the PDARP/PEIS, such plumes were 

documented following the Deepwater Horizon oil spill (Deepwater Horizon Natural Resource 

Damage Assessment Trustees, 2016). If a concentrated plume came into contact with live bottom

organisms, impacts could include mortality, failed reproductive success, reduced biodiversity, 

reduced coverage of fauna and flora on hard substrates, and changes in community structure 

(Reimer, 1975; Guzmán and Holst, 1993; Negri and Heyward, 2000; Silva et al., 2015). Exact 

impacts would depend on the location, age of the spill, and the hydrographic characteristics of the 

area (Bright and Rezak, 1978; Rezak et al., 1983; McGrail, 1982; Le Henáff et al., 2012). However, 

because shallow-water live bottom features are located on the shelf and upwelling events are limited 

to hurricanes, eddy formations, or when certain metrological conditions exist (Walker, 2001; Collard 

and Lugo-Fernandez, 1999; Zavala-Hidalgo et al., 2006), contact of a subsurface plume with a live 

bottom feature would only occur under the most unusual combination of conditions (e.g., Silva et al., 

2015).

The USCG may allow the use of chemical dispersants in certain spill situations. Chemical 

dispersion of oil can help to break up concentrations of oil and accelerate natural weathering 

processes and bacterial biodegradation. Use of dispersants may, however, allow surface oil to 

penetrate to greater depths than normally expected from typical physical mixing, and dispersed oil 

might tend to remain further below the water’s surface than undispersed oil (McAuliffe et al., 1981b; 

Lewis and Aurand, 1997). Reports about dispersant usage on surface plumes indicate that a 

majority of the dispersed oil remains in the top 10 m (33 ft) of the water column, which is generally 

shallower than the crests of OCS live bottom features; therefore, contact is generally not expected 

apart from highly unusual conditions such as those seen in Silva et al. (2015). If contact is made, 

impacts may differ somewhat between oil, oil/dispersant mixtures, and dispersant alone. DeLeo 

et al. (2015) demonstrated that concentrated amounts of dispersant and oil/dispersant mixtures 

caused more severe health declines to live bottom organisms than oil-only mixtures. One field study 

(Yender and Michel, 2010) indicated less severe impacts, possibly due to that study’s (more 

realistic) application of dispersants in an open field system, although during the Deepwater Horizon
4-202 Gulf of Mexico Multisale EIS

oil spill, dispersants were also applied subsea at the source of the blowout. Stratified density layers 

of water allowed the oil/dispersant plume to remain at depth instead of dispersing up into the water 

column (Joint Analysis Group, 2010), and these concentrated plumes are thought to have caused 

serious but fairly localized damage to deepwater corals on the continental slope (White et al., 2012; 

Hsing et al., 2013; Fisher et al., 2014a). It is unlikely that concentrated oil/dispersant mixtures would 

be found near shallow-water live bottom features; therefore, lethal exposures to large numbers of 

shallow-water live bottom organisms are not anticipated.

For any accidental spill, it is expected that a certain quantity of oil may eventually settle on 

the seafloor through a binding process with suspended sediment particles (adsorption) or after being 

consumed and excreted by phytoplankton (Passow et al., 2012). The product of these processes is 

sometimes referred to as “marine snow.” It is expected that the greatest amount of adsorbed oil 

particles would occur close to the spill, with the concentration reducing over distance. If the spill 

occurs close to a live bottom feature, some underlying live bottom organisms may become 

smothered by the particles and experience long-term exposure to hydrocarbons. This was seen for 

some deepwater corals following the Deepwater Horizon oil spill and response (White et al., 2012; 

Hsing et al., 2013; Fisher et al., 2014a). Beyond the localized area of impact in that case, particles 

would become increasingly biodegraded and dispersed. Any localized impacts to pinnacle and lowrelief feature communties would be expected to be largely sublethal and could include reduced 

recruitment success, reduced growth, and reduced biological cover as a result of impaired 

recruitment (Rogers, 1990; Kushmaro et al., 1997).

Sediments suspended or displaced as a result of a loss of well control could also impact 

pinnacle and low-relief feature communties. These impacts would be largely identical to those 

caused by sedimentation stirred up by bottom-disturbing equipment, with the possible addition of 

toxic hydrocarbons or drilling muds in the sediments (refer to “Routine Activities”). Because 

permitted wells would have been distanced from pinnacle and low-relief feature communties before 

installation, it is expected that the heaviest sediment concentrations would fall out of suspension and 

disperse before reaching the communities, preventing most impacts. Some live bottom organisms, 

such as flexible sea fans, are naturally adapted to turbid conditions and may not be as negatively 

affected. Outside of a catastrophic spill situation, a very substantial amount of sediment burial of 

organisms during an accidental spill event is not reasonably foreseeable (refer to the Catastrophic 

Spill Events Analysis white paper, USDOI, BOEM, 2017).

Finally, spill cleanup/response activities could themselves have negative impacts. During a 

response operation, the risk of accidental impacts of bottom-disturbing equipment is increased. 

There could be unplanned or emergency anchoring on live bottom features or accidental losses of 

heavy equipment from responding vessels. Response-related equipment such as seafloor-anchored 

booms may be used and could inadvertently contact live bottom organisms. In addition, drilling 

muds may be pumped into a well to prevent a loss of well control. It is possible that during this 

process, some of this mud may be forced out of the well and deposited on the seafloor near the well 

site. If this occurs, the impacts would be severe for any organisms buried; however, the impact 

beyond the immediate area would be limited and adherence to the original distancing requirements 
Description of the Affected Environment and Impact Analysis 4-203

would prevent or reduce most impacts. Noncatastrophic accidental spills have historically been 

relatively small events (Table 3-12). While the total amount of hard/live bottoms in the GOM is small 

compared with soft bottoms, the habitats are widely distributed and a localized impact from one 

noncatastrophic accidental event would only impact a small fraction of the overall resource 

(McEachran, 2009).

All of the above impact-producing factors could lead to lethal or sublethal impacts on 

individual pinnacle and low-relief feature communities, with the range of impacts dependent on the 

quantity of spilled oil and proximity to habitats. While a spill resulting from a catastrophic-level 

blowout in deep water (such as the Deepwater Horizon oil spill) has the potential to seriously impact 

individual pinnacle and low-relief feature communities over a long time period, such a spill is not 

reasonably foreseeable as a result of a proposed action. Impacts from individual routine activities 

and reasonably foreseeable accidental events are usually temporary, highly localized, and expected 

to impact only small numbers of pinnacle and low-relief feature communties at a time. Some live 

bottom species possess natural adaptations to high-turbidity environments that could help remove 

spill-related sediments. Moreover, use of the expected site-specific plan reviews/mitigations would 

distance activities from identified pinnacle and low-relief feature communities, greatly diminishing the 

likelihood and severity of potential effects. Therefore, at the scale of this analysis, and with 

application of the expected mitigation practices, impacts on pinnacle and low-relief feature 

communities from accidental spills and associated impact-producing factors are expected to range 

from negligible to minor. This range of potential impact levels reflects the relative uncertainties 

associated with unplanned and potentially uncontrolled accidental spills and with the remote 

possibility of unusual weather conditions that could push surface oil/dispersant deeper than is 

typical, potentially leading to a minor level of impact. The exact impact would depend on the overall 

frequency and severity of accidental spills and their proximity to pinnacle and low-relief feature 

communities.

Without the protective measures provided by the Live Bottom Stipulation (which is a required 

mitigation as a result of the Five-Year Program’s Record of Decision), and associated postlease 

reviews and distancing, the potential impacts of accidental spills could rise to moderate or even 

major levels, in the improbable (but theoretically possible) case that a large number of accidental 

spills were to occur at wells in close proximity to a large number of live bottom communities and if 

community-level impacts can be clearly distinguished from a natural variation. Even without 

mitigations, the likelihood is very low that a large number of accidental spills would occur in close 

proximity to the relatively rare hard substrate habitats supporting pinnacle and low-relief feature 

communities, but this possibility cannot be definitively ruled out without knowing both the precise 

distribution of such spills and the communities.

4.6.2.2.3 Cumulative Impacts

The following analysis considers whether the incremental impacts of routine activities and 

accidental events associated with the proposed OCS Oil and Gas Program-related operations, when 
4-204 Gulf of Mexico Multisale EIS

added to or acting synergistically with existing non-OCS oil- and gas- related impact sources from 

the cumulative impacts scenario, may result in a significant collective impact.

OCS Oil- and Gas-Related Impacts

The OCS oil- and gas Program-related impacts include the long-term, incremental 

contribution of the routine and accidental bottom-disturbing activities outlined above: (1) bottomdisturbing activities (e.g., drilling, anchoring, infrastructure installation/removal, and associated 

sedimentation); (2) sediment and waste discharges (e.g., drilling muds and cuttings, and produced 

waters); and (3) oil spills (surface and subsurface and associated cleanup responses). As already 

detailed above, these impact-producing factors have the potential to damage individual pinnacle and 

low-relief feature communities , if insufficiently distanced or otherwise mitigated. Bottom-disturbing 

activities could result in the physical destruction of benthic habitat and organisms or the disturbance 

of sediments within the environment, resulting in burial and/or increased turbidity. Routine and 

accidental waste discharges could be toxic if contacted in undiluted form near the source. Oil spills 

and dispersants are known to have negative, acute effects on benthic organisms, and the 

cumulative, long term effects of persistent, low-level exposure to oil are not yet fully understood. All 

of these activities could lead to lethal or sublethal impacts on individual live bottom communities. 

However, impacts from individual events are usually temporary, highly localized, and expected to 

impact only small numbers of organisms and substrates at a time, particularly since live bottom 

habitats are relatively rare and distributed in only small patches of the OCS areas that are 

anticipated to be leased. Also, adherence to the expected Live Bottom Stipulation and site-specific 

plan reviews/mitigations would distance many of these activities, greatly diminishing potential 

effects. Therefore, the incremental cumulative contribution of the proposed OCS oil- and gas-related 

routine activities and accidental events is expected to have only negligible to minor impacts.

This range of potential impact levels reflects the relative uncertainties associated with 

unplanned accidental bottom disturbances and accidental spills, including the remote possibility of 

unusual weather conditions that could push surface oil/dispersant deeper than is typical, potentially 

leading to a minor level of impact. The exact impact would depend on the overall frequency and 

severity of accidental events and their proximity to pinnacle and low-relief feature communities.

Non-OCS Oil- and Gas-Related Impacts

The cumulative, long-term impact of reasonably foreseeable, non-OCS oil- and gas-related 

anthropogenic activities and influential environmental conditions on live bottoms could be 

considerable, although they are difficult to precisely quantify when projecting future conditions over 

the next 50 years. The primary anthropogenic activities with impact producing factors are vessel 

anchoring and fishing. The primary environmental factors are invasive species, hypoxia, severe 

weather, and climate change. There is extensive scientific literature readily available about all of 

these subjects; only a brief summary analysis is provided here. It should be noted that BOEM’s 

stipulations and site-specific plan reviews/mitigations are not designed to mitigate against the 

potential impacts posed by these non-OCS oil- and gas-related anthropogenic activities and 

environmental factors. They are designed to protect live bottom resources from OCS oil- and gas-
Description of the Affected Environment and Impact Analysis 4-205

related activities within BOEM’s jurisdiction and to mitigate against a proposed action’s incremental 

cumulative impact contribution to the overall OCS and non-OCS cumulative impacts. 

Certain fishing gear and overfishing can have long-term effects on benthic species and 

habitats. These effects can be caused both by the gear and through indirect trophic effects. 

Bottom-tending gear such as bottom trawls and bottom-contacting long lines could destroy or disturb 

hard/live bottoms such that species diversity and abundance are negatively affected (Wells et al., 

2008; NRC, 2014; Pusceddu et al., 2014; Secor et al., 2014). Such gear may dislodge, entangle, or 

otherwise damage organisms inhabiting live bottoms. Large emergent sponges and corals may be 

particularly vulnerable to trawling activity, as these organisms grow above the substrate and can be 

caught and removed by trawling activity (Freese et al., 1999, Hourigan 2014). Because many hookand-line fishermen target live bottom-associated reef fish, they may use bottom-contacting gear that 

can damage the tissues of benthic organisms, particularly when the line is snagged and abandoned. 

In addition, fishing pressure could selectively alter fish community structure and, over the long term, 

have a top-down trophic impact on fish populations that interact with live bottoms.

The impacts of vessel anchoring on live bottoms are similar to the other bottom-disturbing 

impacts described above. Of note in this section is that smaller vessels such as recreational fishing

and diving boats are also included. Such vessels are more numerous than large vessels, though 

their individual anchors are much smaller and most recreational activities occur close to shore. The 

degree of potential damage is dependent on the size of the anchor and chain (Lissner et al., 1991). 

Anchor damages to benthic organisms such as corals may take more than 10 years to recover 

(Fucik et al., 1984; Rogers and Garrison, 2001).

The lionfish is an invasive species of concern that has been reported throughout the GOM 

(USDOI, GS, 2010 and 2015; Johnston et al., 2013; Aguilar-Perera and Tuz-Sulub, 2010). This fish 

is thought to drive down diversity and abundance of benthic organisms, especially crabs, demersal 

fishes, and shrimps (Green et al., 2012). The precise cumulative impact of invasive species on 

GOM live bottom features is still unknown at this time, but it is projected that negative impacts are 

likely to worsen over time as lionfish populations are increasing exponentially in both abundance and 

distribution (Switzer et al., 2015).

Depleted dissolved oxygen occurs seasonally in shelf waters of the northern GOM, including 

in areas with pinnacle and low-relief feature communties . Dissolved oxygen depletion is caused 

primarily by the decomposition of algae whose production is stimulated by excess nutrients delivered 

by the Mississippi River and other coastal rivers, the source of which can be traced back to onshore 

human activities such as fertilizer use. Hypoxic (dissolved oxygen ≤2.0 mg/L) conditions can have 

lethal and sublethal effects on aquatic organisms (refer to Chapter 3.3.2.12 for more information on 

hypoxia). Although hypoxic conditions are mainly a characteristic of Louisiana-Texas shelf waters, 

negative effects could reach some pinnacle and low-relief feature communties in the northeast 

portion of the CPA. Dramatic changes in natural levels of dissolved oxygen over time could alter the 

composition and distribution of live bottom communities.
4-206 Gulf of Mexico Multisale EIS

Severe weather events of sufficient magnitude (e.g., hurricanes) may also cause impacts. 

The force of currents and wave action can directly disturb sediments (Brooks, 1991; CSA, 1992), 

increasing turbidity and associated impacts. Severe weather can also have secondary impacts, 

such as causing movement of abandoned fishing gear and causing accidental losses of equipment 

overboard or even the toppling of entire platforms. In general, live bottom communities have 

adapted over millennia to deal with natural levels of severe weather, but changing climatic conditions 

that alter the frequency and/or severity of severe weather events could impact live bottom resources 

in unforeseen ways to which live bottoms may not be able to adapt.

Climate change-related effects have the potential to alter baseline environmental conditions 

throughout the GOM. An additional review of climate change is presented in the Five-Year Program 

EIS (USDOI, BOEM, 2016b). Of particular note for pinnacle and low-relief feature communties are 

the potential negative consequences that may be caused by the dual mechanisms of increasing 

ocean temperatures and ocean acidification. Sustained, unusually high water temperatures are 

documented to cause coral bleaching, in which symbiotic zooxanthellae are expelled from coral 

polyps. Ocean acidification can reduce the bioavailability of calcium carbonate and thereby inhibit 

normal rates of calcification by exoskeleton-building corals and other calcifying marine organisms. 

Decreased calcification rates have been observed in numerous shallow-water, zooxanthellate corals 

(refer to Hoffman et al., 2010). Both mechanisms can inhibit growth and reproductive fitness. Other 

potential climate change-driven alterations of baseline environmental conditions, such as sea-level 

rise, could also have additional, unpredictable effects on sessile benthic organisms.

The cumulative impact level of each of these individual factors is difficult to accurately 

estimate since the spatial and temporal characteristics of some factors are rapidly changing and 

necessary baseline information is still being collected. However, at present, the overall impact of 

these non-OCS factors is estimated to be minor to moderate, with individual species affected to 

different degrees by each factor. Over the next 50 years, the impact level from these non-OCS 

factors could potentially rise to higher levels, even possibly major, should current trends of these 

non-OCS oil- and gas-relatedactivities continue or worsen.

Weighed against these potential non-OCS oil- and gas-related impacts from anthropogenic 

activities and influential environmental conditions, the much smaller incremental cumulative impact 

of a proposed lease sale is expected to contribute only a negligible to minor amount to the total 

potential level of impacts. Based on current conditions, the overall cumulative impact of everything 

(OCS and non-OCS) is minor to moderate, with almost all of the impacts coming from non-OCS oiland gas-related activities. This total impact level has the potential to rise over the next 50 years to 

higher levels, even possibly to major, should projected trends of non-OCS oil- and gas-related 

activities (particularly climate change) continue or worsen. Given the negligible to minor

contribution of a proposed lease sale to this overall cumulative scenario, it is reasonable to conclude 

that a single proposed lease sale would not cause the overall cumulative impact level to rise over the 

next 50 years.
Description of the Affected Environment and Impact Analysis 4-207

4.6.2.2.4 Incomplete or Unavailable Information

BOEM recognizes that there is incomplete or unavailable information related to GOM live 

bottom habitats in general and specifically in relation to routine activities, accidental events, and 

cumulative impacts for OCS oil- and gas-related activities and cumulative non-OCS oil- and gasrelated activities. However, the information that is known is adequate to come to a determination 

with respect to reasonably foreseeable impact-producing factors associated with a proposed action.

Research in offshore marine systems is logistically complex and requires substantial 

resources to conduct. The total amount of research on live bottom habitats has therefore been 

limited, although BOEM and its predecessor agencies have funded numerous studies over the past 

40 years. An example of incomplete knowledge about this resource would be that the exact 

distribution of GOM live bottom habitats at any given time is not perfectly understood. This is due in 

part to limits on data collection but also due to the frequent burial and exposure of low-relief hard 

bottoms. To help address this knowledge gap, BOEM requires operators to provide detailed, 

updated, site-specific survey information about potential live bottom habitats; this information is 

reviewed by subject-matter experts prior to approval of individual proposed activities, and 

appropriate protective mitigations are applied where appropriate.

Although BOEM has acquired and applies a large amount of knowledge about possible 

impacts to live bottom habitats, a perfect understanding of all conceivable impacts is unattainable. 

For example, only recently did a study (Silva et al., 2015) provide compelling evidence that mixing of 

a surface oil/dispersant mixture to the depths of the Pinnacle Trend live bottom features can actually 

occur, given an unusual combination of conditions, and could then have a localized impact. Given 

the geographic and temporal scope of a proposed action, it is believed that even impacts resulting 

from that particular scenario would still only have a slight impact on the overall status of GOM 

pinnacle and low-relief feature communities. Moreover, the amount of oil/dispersant mixture in that 

catastrophic situation greatly exceeded the amounts considered in the “Accidental Events” analysis. 

However, the example demonstrates the point that the body of literature supporting impact analysis 

is still growing and requires continual review by BOEM.

Known information about potential impacts of a theoretical catastrophic spill is detailed in the 

Catastrophic Spill Events Analysis white paper (USDOI, BOEM, 2017), and further information was 

made available with the publication of the Trustees’ PDARP/PEIS in 2016 (Deepwater Horizon

Natural Resource Damage Assessment Trustees, 2016). The content of that report was reviewed 

as part of this analysis. Some information related to impacts specific to the Deepwater Horizon

explosion, oil, spill, and response, such as long-term monitoring results, is still incomplete or 

unavailable. BOEM has determined that such additional information could not be timely acquired 

and incorporated into the current analysis. However, based on the currently available evidence, 

impending reports are not expected to reveal additional significant effects that would alter the overall 

conclusions about reasonably foreseeable impact-producing factors associated with a proposed 

action.
4-208 Gulf of Mexico Multisale EIS

BOEM will continue to analyze and support collection and analysis of the best available 

scientific information related to live bottom habitats. BOEM used reasonably accepted scientific 

methodologies to extrapolate from existing information in completing this analysis and formulating 

the conclusions presented here. BOEM has determined that the incomplete information is not 

essential to a reasoned choice among alternatives.

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

The activities proposed under Alternative A could directly impact live bottom pinnacle and 

low-relief features within the GOM. The primary, reasonably foreseeable, impact-producing factors 

for pinnacle and low-relief feature communities can be grouped into three main categories: 

(1) bottom-disturbing activities; (2) sediment and waste discharges; and (3) oil spills. The proposed 

Live Bottom Stipulation (which is a required mitigation as a result of the Five-Year Program’s Record 

of Decision), along with site-specific reviews of permit applications and associated distancing 

requirements, would mitigate potential impacts to the communities as a result of both routine 

activities and accidental disturbances. Assuming adherence to all expected lease stipulations and 

other postlease protective restrictions and mitigations, the routine activities are expected to have 

mostly short-term, localized, and temporary effects on the communities that may not be clearly 

detectable. Therefore, at the regional, population-level scope of this analysis, the impacts of routine 

activities would be expected to be negligible. 

Accidental events (below the threshold of a catastrophic spill, which is detailed in the 

Catastrophic Spill Event Analysis white paper [USDOI, BOEM, 2017]) have the potential to cause 

detectable, severe damage to specific pinnacle and low-relief feature communities. However, the 

number of such events is expected to be very small and localized, and impacts might not be clearly 

distinguishable from natural variation. Therefore, at the regional, population-level scope of this 

analysis, impacts from reasonably foreseeable accidental events are expected to be negligible to 

minor. 

Proposed and existing OCS oil- and gas-related activities would also contribute 

incrementally, but only a negligible to minor amount, to the overall OCS oil- and gas-related and 

non-OCS oil- and gas-related cumulative effects experienced by pinnacle and low-relief feature 

communities. Absent the expected mitigations, the impacts resulting from both routine activities and 

accidental events of a proposed lease sale could be greater, with overall population-level impacts 

ranging from minor to major (in a theoretical, if improbable, worst-case scenario). The previous and 

continuing OCS oil- and gas-related cumulative impacts beyond the incremental contribution of a 

proposed action (a specific lease sale) are estimated to continue having only negligible to minor

impacts, assuming continued adherence to all expected lease stipulations and other postlease 

protective restrictions and mitigations.

A variety of non-OCS oil- and gas-related activities, including fishing and anchoring, along 

with shifting natural conditions such as invasive species and climate change-related factors, seem 

likely to have a considerably greater impact on the communities; currently, that impact level is 
Description of the Affected Environment and Impact Analysis 4-209

estimated as minor to moderate, but it could increase to as great as major over the next 50 years. 

Ongoing non-OCS oil- and gas-related activities are difficult to accurately estimate since the spatial 

and temporal characteristics of some factors are rapidly changing, and necessary baseline 

information is still being collected; however, at present, these non-OCS oil- and gas-related activities 

are having minor to moderate cumulative impacts on pinnacle and low-relief feature communities. 

These could potentially become greater over time, even rising to major over the next 50 years, 

should current trends of these activities continue or worsen, regardless of whether or not a proposed 

lease sale would be held. Weighed against these potential non-OCS oil- and gas-related impacts 

from anthropogenic activities and influential environmental conditions, the much smaller incremental 

cumulative impact of a proposed lease sale is expected to contribute only a negligible to minor

amount to the total potential level of impacts.

4.6.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM would hold a lease sale excluding the available unleased WPA 

blocks and would offer all available unleased blocks in the CPA and a portion of the EPA. 

Alternative B would not fundamentally alter the conclusions reached under Alternative A, but it would 

reduce the potential impacts of a proposed sale in the available unleased WPA blocks. The impacts 

from proposed activities to pinnacle and low-relief feature communities would remain the same in 

leased portions of the CPA/EPA. Impacts resulting from accidental events should remain relatively 

localized, with the number of features affected being directly proportional to the size of the accident. 

An accident along the CPA/WPA border has the possibility to impact features in either planning area. 

Pinnacle and low-relief feature communities are found throughout the GOM, and therefore, the 

impacts associated with Alternative B could still potentially cause some population-level effects.

At the regional, population-level scope of this analysis, the overall impact to the communities 

as a result of the activities proposed under Alternative B are expected to be the same as 

Alternative A, assuming the application of the Live Bottom (Pinnacle Trend) Stipulation (which is a 

required mitigation as a result of the Five-Year Program’s Record of Decision), and continuation of 

expected mitigation practices. BOEM’s mitigation practices would limit the potential impacts as a 

result of routine activities to negligible levels and would limit impacts from reasonably foreseeable 

accidental events to the range of negligible to minor. The OCS oil- and gas-related cumulative 

impacts of a proposed lease sale under Alternative B would be negligible to minor for a single 

proposed lease sale (the incremental contribution) and negligible to minor for the overall ongoing 

OCS oil and gas program.

However, absent the expected mitigations, the impacts resulting from both routine activities 

and accidental events of a proposed lease sale could be greater, with overall population-level 

impacts ranging from minor to moderate (in a theoretical, if improbable, worst-case scenario). This 

impact-level range is lower than the potential minor to major level impact range that would be 

possible (absent mitigations) under Alternative A. This difference is due to the reduced area 

available for new leasing under Alternative B, which would somewhat limit the number of potentially 
4-210 Gulf of Mexico Multisale EIS

affected pinnacle and low-relief feature communities (including concentrations of such communities 

in the South Texas Banks) and increase the likelihood of eventual recovery to pre-impact levels, 

should impacts occur. However, it is believed that existing mitigation practices would continue to be 

applied to the proposed activities under all action alternatives.

The incremental cumulative impacts of proposed OCS oil- and gas-related activities of a 

single proposed lease sale under Alternative B would still add only a negligible to minor

contribution to the overall cumulative impact, which includes the relatively greater influence of 

non-OCS cumulative impacts occurring throughout the GOM over the 50-year analysis period.

4.6.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

Under Alternative C, BOEM would hold a lease sale excluding the CPA/EPA available 

unleased blocks and would only offer all available unleased blocks in the WPA. Alternative C would 

not fundamentally alter the conclusions reached under Alternative A, but it would reduce the 

potential impacts of a proposed lease sale of the available unleased CPA/EPA blocks, including 

known high concentrations of pinnacle and low-relief feature communities in the Pinnacle Trend

blocks and other portions of the northeastern CPA (Figure 4-17). The impacts from proposed 

activities to the communities would remain the same in leased portions of the WPA. Impacts 

resulting from accidental events should remain relatively localized, with the number of features 

affected being directly proportional to the size of the accident. An accident along the CPA/WPA 

border has the possibility to impact features in either planning area. Live bottom communities are 

found throughout the GOM, not just in the CPA/EPA, and therefore, the impacts associated with 

Alternative C could still potentially cause some population-level effects.

At the regional, population-level scope of this analysis over the next 50 years, the potential 

impacts to pinnacle and low-relief feature communties as a result of the activities proposed under 

Alternative C are expected to be slightly reduced from the impact levels detailed in Alternatives A 

and B because such a large proportion of the Gulfwide population of pinnacle and low-relief feature 

communities are found within the CPA, especially within the Pinnacle Trend region. Therefore, the 

population would not be subjected to the same degree of potential accidental impacts theorized 

above, and the reduced theoretical impact would also increase the likelihood of eventual population 

recovery to pre-impact levels. BOEM’s mitigation practices would further limit the potential impacts 

in leased areas. Under Alternative C, both routine activities and foreseeable accidental events are 

estimated to result in only negligible levels. The OCS oil- and gas-related impacts of a proposed 

lease sale under Alternative C would therefore be negligible for a single proposed lease sale (the 

incremental contribution) and negligible to minor for the overall ongoing OCS oil and gas program. 

Should Alternative C be selected for multiple subsequent proposed lease sales in the future, 

however, impacts from the cumulative OCS Oil and Gas Program could eventually be reduced to 

negligible as overall OCS oil- and gas-related activity in the CPA would begin to appreciably decline 

over time.
Description of the Affected Environment and Impact Analysis 4-211

Absent these expected mitigations, the impacts resulting from routine activities and 

accidental events of a proposed lease sale could be greater, with overall population-level impacts 

ranging from negligible to minor for routine activities and from negligible to minor (in a theoretical, 

if improbable, worst-case scenario) for accidental events. These impact-level ranges are less than 

the potential impact-level ranges that would be possible (absent mitigations) under Alternatives A 

and B. This difference is due to the reduced area available for new leasing under Alternative C, 

which would somewhat limit the number of potentially affected pinnacle and low-relief feature 

communities (including large concentrations of known communities in the Pinnacle Trend blocks and 

other portions of the northeastern CPA) and increase the likelihood of eventual population recovery 

to pre-impact levels. However, the existing mitigation practices are now a required mitigation as a 

result of the Five-Year Program’s Record of Decision and would continue to be applied to the 

proposed activities under all action alternatives, reducing the expected level of OCS oil- and 

gas-related impacts.

The incremental cumulative impacts of proposed OCS oil- and gas-related activities of a 

single proposed lease sale under Alternative C would likely add only a negligible contribution to the 

overall cumulative impact, which includes the relatively greater influence of non-OCS cumulative 

impacts occurring throughout the GOM over the 50-year analysis period.

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, BOEM could hold a lease sale excluding leasing on any and/or all 

blocks subject to the Topographic Features, Live Bottom (Pinnacle Trend), and Blocks South of 

Baldwin County, Alabama, Stipulations. Known pinnacle and low-relieft features in the Pinnacle 

Trend area would be further protected by the increased distancing of OCS oil- and gas-related 

activities. An accidental spill could still reach some Pinnacle Trend features, but if so, it is expected 

that oil from such a spill would be more dispersed and diluted due to it having to travel the additional 

distance across the areas not offered for lease.

Impacts resulting from accidental events should remain relatively localized, with the number 

of features affected being directly proportional to the size and location of the accident. An accident 

along the border of available unleased blocks subject to the Topographic Features and Live Bottom

(Pinnacle Trend) Stipulations still has the possibility to impact features within those unleased blocks. 

Live bottom communities are found throughout the GOM, not just in the blocks subject to the 

Topographic Features and Live Bottom (Pinnacle Trend) Stipulations, and therefore, the impacts 

associated with Alternative D could still potentially cause some population-level effects. The 

exclusion of blocks subject to the Blocks South of Baldwin County, Alabama, Stipulations is not 

expected to change the impacts to pinnacles and/or low-relief features because of the small number 

of these blocks and their distance from known pinnacle and low-relief features.
4-212 Gulf of Mexico Multisale EIS

At the regional, population-level scope of this analysis over the next 50 years, the potential 

impacts to pinnacle and low-relief feature communties as a result of the activities proposed under 

Alternative D are expected to be slightly reduced from the impact levels detailed in Alternatives A 

and B because such a large proportion of the Gulfwide population of pinnacle and low-relief feature 

communities are found within the CPA, especially within the Pinnacle Trend region. There are also 

a fair number of pinnacle and low-relief features within blocks subject to the Topographic Features

Stipulation (specifically on the peripheral flanks of some of the much larger topographic features). 

Therefore, the Gulfwide population of pinnacle and low-relief feature communities would not be 

subjected to the same degree of potential accidental impacts theorized above for Alternatives A 

and B, and the reduced theoretical impact would also increase the likelihood of eventual population 

recovery to pre-impact levels. BOEM’s mitigation practices would further limit the potential impacts 

in leased areas. Under Alternative D, both routine activities and foreseeable accidental events are 

estimated to result in only negligible levels. The OCS oil- and gas-related impacts of a proposed 

lease sale under Alternative D would therefore be negligible for a single proposed lease sale (the 

incremental contribution) and negligible to minor for the overall ongoing OCS oil and gas program. 

Should Alternative D be selected for multiple subsequent proposed lease sales in the future, 

however, impacts from the cumulative OCS Oil and Gas Program could eventually be reduced to 

negligible as overall OCS oil- and gas-related activity in the CPA would begin to appreciably decline 

over time. Absent these mitigations, the impacts resulting from routine activities and accidental 

events of a proposed lease sale under Alternative D could be greater. The overall population-level 

impact could range from negligible to minor for routine activities and from negligible to minor (in a 

theoretical, if improbable, worst-case scenario) for accidental events. This impact level is less than 

the potential major level impact that would be possible (absent mitigations) under Alternative A. 

These impact-level ranges are less than the potential impact-level range that would be possible 

(absent mitigations) under Alternatives A and B. This difference is due to the reduced area available 

for new leasing under Alternative D, which would limit the number of potentially affected pinnacle 

and low-relief feature communities (including large concentrations of known communities in the 

Pinnacle Trend blocks) and increase the likelihood of eventual population recovery to pre-impact 

levels. However, it is believed that existing mitigation practices would continue to be applied to the 

proposed activities under all action alternatives, reducing the expected level of OCS oil- and

gas-related impacts.

The incremental cumulative impacts of proposed OCS oil- and gas-related activities of a 

single proposed lease sale under Alternative D would likely add only a negligible contribution to the 

overall cumulative impact, which includes the relatively greater influence of non-OCS cumulative 

impacts occurring throughout the GOM over the 50-year analysis period.

4.6.2.2.9 Alternative E—No Action

Under Alternative E, a proposed lease sale would be cancelled. Therefore, the potential for 

impacts would be none because new impacts to pinnacle and low-relief feature communities related 

to the cancelled lease sale would be avoided entirely. Continuing impacts to the communities would 

be limited to existing impacts resulting from routine activities and accidental events, and cumulative 
Description of the Affected Environment and Impact Analysis 4-213

impacts associated with previous OCS lease sales. BOEM’s current Live Bottom Stipulation and 

mitigation practices already regulate these activities and should continue to limit associated new 

impacts to the negligible level.

Ongoing non-OCS oil- and gas-related activities are difficult to accurately estimate since the 

spatial and temporal characteristics of some factors are rapidly changing, and necessary baseline 

information is still being collected; however, at present, these non-OCS oil- and gas-related activities 

are having minor to moderate cumulative impacts on live bottom communities. These could 

potentially become greater for some species, even rising to major over the next 50 years, should 

current trends of these factors continue or worsen, regardless of whether or not a proposed lease 

sale would be held.

4.7 FISHES AND INVERTEBRATE RESOURCES

Fish and invertebrate resources of the GOM comprise a large and diverse group of species 

(Felder et al., 2009). The distribution of fishes and invertebrates vary widely and species may be 

associated with different habitats at various life stages. This analysis highlights behaviors and 

habitat preferences, but it does not attempt to provide a comprehensive list of all potentially 

impacted fauna. For purposes of this analysis, habitat preferences can be divided into three broad 

categories: estuarine; coastal; and oceanic. Exposure to specific impact-producing factors 

generated by OCS oil- and gas-related routine activities and accidental events can vary among 

these categories. Coastal and oceanic resources are further broken into benthic and pelagic zones 

to address differences in potential exposure to impact-producing factors within a given habitat 

category. Ichthyoplankton bridges all three categories. Egg and larval stages of most fishes and 

invertebrates can be found in the upper layer of the water column, exposing these species’ early life 

stages to similar impact-producing factors. For these reasons, the description of the affected 

environment for fish and invertebrate resources is broken into estuarine, coastal, and oceanic 

habitats, with ichthyoplankton being treated separately due to the potentially broader distribution of 

egg and larval lifestages across these habitats. A brief discussion of the federally managed species 

is provided at the end of the “Description of the Affected Environment” below (Chapter 4.7.1).

A full analysis of the “Environmental Consequences” is presented in Chapter 4.7.2. 

Analyses of the specific alternatives do not restate the full analysis of the impact-producing factors 

potentially affecting fishes and invertebrate resources; the analyses identify the potential impacts as 

a result of routine activities, accidental events, and cumulative impacts. This avoids excessive 

replication of the discussion of similar if not identical impacts for each alternative.

Preliminary analysis of routine OCS oil- and gas-related activities and reasonably 

foreseeable accidental events identified eight impact-producing factors with the potential to affect 

marine fishes and invertebrates and/or their habitat. Many OCS oil- and gas-related activities affect 

the environment similarly. For example, vessel traffic, exploratory drilling, geophysical activities, and 

offshore construction all produce sound. The impact-producing factor, “anthropogenic sound,” was 
4-214 Gulf of Mexico Multisale EIS

analyzed taking all sound-producing OCS activities into consideration. The following are impactproducing factors that were considered and analyzed in this resource analysis:

• anthropogenic sound (Chapter 3.3.2.7);

• bottom-disturbing activity (Chapter 3.1.3.3.2);

• habitat modification; and

• oil spills (Chapter 3.2.1).

Two of the eight impact-producing factors that were considered for fishes and invertebrate 

resources were determined to be insignificant under all reasonably foreseeable circumstances due 

to the limited exposure and/or response expected for fish and invertebrate resources and are, 

therefore, not analyzed in this chapter. These impact-producing factors are entrainment (Chapter 

3.1.5.1.6) and offshore lighting (Chapter 3.1.3.4.3). A Joint Industry Biological Baseline Study was 

completed for USEPA Region 6 in June 2009 (LGL Ecological Research Associates, Inc., 2009), and 

an industry-wide cooling water intake structure entrainment monitoring study, approved by USEPA 

Region 6, was completed in 2014 (CSA and LGL Ecological Research Associates, Inc., 2014). The 

results of these two studies support BOEM’s finding that entrainment is insignificant as an impactproducing factor for the purpose of this analysis. Analyses of two additional impact-producing 

factors that could potentially impact resources ecologically important to fishes and invertebrates 

were addressed in earlier chapters. Discussions of onshore construction and use of coastal support 

infrastructure (Chapter 4.3, Coastal Habitats) and regulated discharges (Chapters 3.1.5 and 4.2, 

Water Quality) were found to sufficiently address the potential for adverse impacts to fish and 

invertebrate habitats and are not duplicated in this chapter.

Analysis of potential impacts considered the estimated scale of source activities and used 

the best available science to evaluate how specific impact-producing factors could affect resources 

within the expected environment. Cumulative impacts (Chapter 4.7.2.3) were analyzed for OCS oiland gas-related activities and for other sources that could affect fishes and invertebrates (e.g., 

coastal development, commercial shipping, fisheries, and environmental). Because of the diversity 

of fishes and invertebrates, detailed criteria for potential impact levels are not reasonable.

Impact-Level Definitions

For this analysis, the potential impact-level criteria can be described in terms of populationlevel effects.

• Negligible – localized and temporary impacts that are expected to be 

indistinguishable from natural variations in population distribution and 

abundance.

• Minor – localized and temporary impacts that are expected to be 

indistinguishable from natural variations in population distribution and 
Description of the Affected Environment and Impact Analysis 4-215

abundance. Community-level variations may be locally detectable, such as 

species mix and relative abundance following the removal of OCS oil- and gasrelated infrastructure. 

• Moderate – Impacts would be expected to exceed natural variations in 

population abundance or distribution, but not result in a long-term decline.

• Major – Impacts would be expected to exceed natural variations and inherently 

result in a long-term decline in populations.

Though two protected fish species (Gulf sturgeon [Acipenser oxyrhynchus desotoi] and 

smalltooth sawfish [Pristis pectinata]) are found near the area of interest, they inhabit and have 

critical habitat in onshore waters. A third protected species, Nassau grouper (Epinephalus striatus), 

has been documented as a transient or rarely occuring species in the area of interest. These 

species are not considered to be impacted by a proposed action because they are found away from 

activities that could cause an impact. The impact-producing factors analyzed and the impact-level 

conclusions reached from the analysis in this chapter are presented in Table 4-15 to help the reader 

quickly identify the level of potential impacts for each relevant impact-producing factor. The 

analyses supporting these conclusions are then discussed in detail after a description of the relevant 

affected environment for fish and invertebrate resources in the GOM.

Table 4-15. Fish and Invertebrate Resources Impact-Producing Factors That Are Reasonably 

Foreseeable.

Fish and 

Invertebrate 

Resources

Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Anthropogenic 

Sound Minor Minor Minor Minor None

Bottom-Disturbing 

Activity Negligible Negligible Negligible Negligible None

Habitat 

Modification

Negligible to Negligible to Negligible to Negligible to None

Minor Minor Minor Minor

Accidental Impacts

Oil Spills Negligible Negligible Negligible Negligible None

Cumulative Impacts

Incremental 

Contribution2 Minor Minor Minor Minor None

OCS Oil and Gas3

Anthropogenic 

Sound Minor

Bottom-Disturbing 

Activity Negligible
4-216 Gulf of Mexico Multisale EIS

Fish and 

Invertebrate 

Resources

Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Habitat 

Modification

Negligible to

Moderate

Non-OCS Oil and Gas4

Anthropogenic 

Sound Moderate

Fisheries Negligible to

Moderate

Habitat 

Modification Minor

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

4.7.1 Description of the Affected Environment

The ecological factors influencing the distribution of fish and invertebrate species include 

salinity, temperature, depth, primary productivity, and bottom type. These factors vary widely across 

the Gulf of Mexico and between inshore and offshore waters. Fish and invertebrate resources are 

associated with the various environments and are not randomly distributed. High densities of fish 

and invertebrate resources can be associated with particular habitat types; for detailed habitat 

information, distribution, potential impacts, and mitigations, refer to Chapters 4.3 (Coastal Habitats), 

4.4 (Deepwater Benthic Communities), 4.5 (Sargassum and Associated Communities), and 4.6 (Live 

Bottom Habitats), and to the Essential Fish Habitat Assessment white paper (USDOI, BOEM, 

2016d). Because wide variations in habitat usage can occur throughout a species’ life history, 

potential impacts have been analyzed in three broad habitat categories (i.e., estuarine, coastal, and 

oceanic) and one life history category (i.e., ichthyoplankton). These categories are not divided by 

fixed boundaries but by generalized conditions and characteristics typical of the habitat where a fish 

or invertebrate may spend the bulk of its life, although individuals are likely to use multiple habitat 

types and/or move frequently through different areas of the water-column, including surface waters.

Estuarine

Estuaries are typically semi-enclosed areas where marine saltwater is diluted by freshwater 

and where salinity may vary widely from day to day. The freshwater input (e.g., bayou, stream, or 

river) delivers sediment and nutrients that result in turbid, productive environments. Estuaries 

include many important habitat types (e.g., wetlands, seagrasses, and mudflats) and are frequently 
Description of the Affected Environment and Impact Analysis 4-217

areas with high biomass. However, these environments can also have high energetic costs for 

resident organisms due to the fluctuating conditions. Many of the fishes and invertebrates found in 

mid- or near-shelf waters are dependent on or opportunistically make use of estuaries at some point 

in their life cycle. For example, estuaries provide nursery habitat for Gulf menhaden (Brevoortia 

patronus), spotted sea trout (Cynoscion nebulosus), blue crab (Callinectes sapidus), brown shrimp 

(Farfantepenaeus aztecus), and gag (Mycteroperca microlepis). The eastern oyster (Crassostrea 

viginica) is an example of a species that both benefits from the environmental conditions in estuarine 

habitat and serves as an important substrate. Bull sharks (Carcharhinus leucas) opportunistically 

make use of estuarine habitat and are common in estuaries and coastal waters. Estuaries may be 

subject to extreme tidal exchange, strong currents, water-column stratification, and/or rapid 

fluctuations in dissolved oxygen.

Coastal

Coastal waters are defined here as those waters extending from the shoreline seaward over 

the continental shelf. These waters are enriched by organic material exported from the estuaries 

and rivers of the GOM and support the greatest biomass of the three categories. Many species in 

the coastal waters of the GOM exploit the entire water column; the following subcategories are used 

to distinguish between zones in which species are predominantly found.

Coastal Pelagics

Pelagic fishes are primarily found in waters associated with neither the shore nor the 

seafloor. Commercial fishery landings are one of the best sources of information for coastal pelagic 

fishes because these species are an important component of regional fisheries. Coastal pelagic 

species traverse shelf waters of the region throughout the year. Major coastal pelagic families 

occurring in the region include

• Carcarhinidae (requiem sharks), 

• Elopidae (ladyfish), 

• Engraulidae (anchovies), 

• Clupeidae (herrings), 

• Scombridae (mackerels and tunas), 

• Carangidae (jacks and scads), 

• Mugilidae (mullets), 

• Pomatomidae (bluefish), and 

• Rachycentridae (cobia).

The distribution of most species depends upon water-column characteristics that vary 

spatiotemporally. Coastal pelagic species with an affinity for vertical structure are often observed 
4-218 Gulf of Mexico Multisale EIS

around topographic features and offshore platforms, where they are best classified as transients 

rather than resident fishes. Spawning typically occurs over the mid- or inner-continental shelf, eggs 

and larvae are pelagic, and juveniles are common in estuaries and coastal waters. Coastal pelagic 

fishes can be divided into two general groups: large predatory species (e.g., Spanish mackerel, 

cobia, and coastal sharks); and smaller, omnivorous and herbivorous species, such as Gulf 

menhaden and striped mullet (Mugil cephalus). Members of both groups may form large schools. 

The predatory species typically undergo migrations, grow rapidly, mature early, and exhibit the ability 

to produce a large number of eggs, while the latter group includes many estuarine-dependent 

species that are frequently preyed upon by members of the first group. These fishes are ecologically 

important to energy transfer in the nearshore environment and, in many cases, are subject to 

significant fishing pressure. Large schools of squid (e.g., Doryteuthis pealeii and Lolliguncula brevis) 

can also be found over the continental shelf, and many less well-known cephalopods inhabit the 

GOM, ranging from nearshore waters to oceanic waters (Voss and Brakoneicki, 1985; Felder et al., 

2009).

Coastal Demersal

Most of the benthic habitat in the northern GOM can be described as low-relief soft bottom

habitat (i.e., mud, clay, and sand). Demersal fish and benthic invertebrates live and forage at the 

seafloor. White shrimp (Litopenaeus setiferus), hardhead catfish (Arius felis), Atlantic croaker 

(Micropogonias undulatus), and cownose rays (Rhinoptera bonasus) are common to inshore soft 

bottom habitat. Over the inner- and mid-shelf, and in association with deeper topographic features, 

red snapper (Lutjanus campechanus) provide an example of an opportunistic fish. This species 

feeds on the bottom and throughout the water column. Older and larger fish inhabit open bottom 

and habitat with vertical structure, whereas young adults tend to recruit to habitat with vertical 

structure (Gallaway et al., 2009). Scattered low-relief hard bottom features and several significant 

higher relief features are located on the shelf. Thirteen banks have been identified by the Gulf of 

Mexico Fisheries Management Council (GMFMC) as being important features in the northwestern 

GOM, and these banks are designated as habitat areas of particular concern (HAPCs). More 

information on HAPCs is available in the Essential Fish Habitat Assessment white paper (USDOI, 

BOEM, 2016d). Where hard bottom occurs, demersal species and opportunistic reef fish species 

more commonly associated with the mid- or inner-shelf may also be found. Species particularly 

adapted for deeper hard bottom areas include snowy grouper (Epinephelus niveatus), yellowedge 

grouper (Epinephelus flavolimbatus), and gag. Outer shelf demersal assemblages (approximately 

656- to 984-ft [200- to 300-m] water depth) might include three-eye flounder (Ancylopsetta dilecta), 

deepbody boarfish (Antigonia capros), and armored searobins (Peristedion miniatum).

Oceanic

For purposes of this impact analysis, oceanic waters are generally defined as those waters 

seaward of the continental shelf, although oceanographic features and storms can cause these 

waters to intrude over the mid- or inner-shelf. Information on the distribution and abundance of 

oceanic species comes from commercial longline catches, recreational fishing surveys, and 

relatively few independent research efforts. Pelagic fishes occur throughout the water column in the 
Description of the Affected Environment and Impact Analysis 4-219

open ocean. Within this vast habitat, water-column structure (i.e., temperature, salinity, and 

turbidity) is the primary means of partitioning for analyses. In general, pelagic fishes recognize 

different watermasses based upon physical and biological characteristics. The following 

subcategories are used to distinguish among assemblages based on predominant depth inhabited: 

epipelagic – extends from the surface to a depth of 656 ft (200 m); mesopelagic – extends from 

656 to 3,281 ft (200 to 1,000 m); and bathypelagic – includes depths greater than 3,281 ft (1,000 m). 

The demersal category is also included and encompasses those species associated with the deep 

seafloor.

Epipelagic

Oceanic epipelagic species occur throughout the GOM, especially at or beyond the shelf 

edge. Epipelagics are reportedly associated with mesoscale hydrographic features such as fronts, 

eddies, and discontinuities. Many of the oceanic fishes also associate with drifting Sargassum, 

which provides forage areas and/or nursery refugia (Chapter 4.5, Sargassum and Associated 

Communities). Common fishes in this zone include halfbeaks and flying fishes (Exocoetidae), and 

early life stage driftfishes (Ariommatidae). Several well-known large predators are also epipelagic 

species, including bluefin tuna (Thunnus thynnus), swordfish (Xiphias gladius), dolphinfish 

(Coryphaena hippurus), wahoo (Acanthocybium solanderi), and shortfin mako (Isurus oxyrinchus). 

The lower section of this epipelagic zone has a distinct fauna, consisting of the poorly known 

oarfishes and its relatives, in addition to fishes with great depth ranges such as tunas (Scombridae) 

and swordfishes (Xiphiidae) (McEachran and Fechhelm, 1998). Adult driftfishes are generally found 

at depths bridging the lower epipelagic and upper mesopelagic zones.

Mesopelagics

The mesopelagic realm is below the photic zone and below the permanent thermocline. 

Mesopelagic fish assemblages in the GOM are numerically dominated by myctophids 

(lanternfishes), with gonostomatids (bristlemouths) and sternoptychids (hachetfishes) common but 

less abundant in collections. These fishes make extensive vertical migrations during the night from 

mesopelagic depths (200-1,000 m; 656-3,281 ft) to feed in higher, food rich layers of the water 

column (McEachran and Fechhelm, 1998). Mesopelagic fishes are ecologically important because 

they transfer substantial amounts of energy between mesopelagic and epipelagic zones over each 

diel cycle.

Bathypelagics

The deeper dwelling bathypelagic fishes inhabit the water column at depths >1,000 m 

(3,281 ft) and seldom migrate into shallower waters. This zone receives no sunlight and 

temperatures range from 4 °C to 10 °C (39 °F to 50 °F). Numerous species of gonostomatids 

(bristlemouths or lightfishes) and scaleless black dragonfishes (Melanostomiidae) are found in the 

bathypelagic of the GOM. Like mesopelagic fishes, most species are capable of producing and 

emitting light (bioluminescence) to aid in communication in an environment devoid of sunlight 

(Snyder, 2000).
4-220 Gulf of Mexico Multisale EIS

Demersal

Three major deep-sea studies have collected demersal fish throughout the depth range of 

the GOM’s continental slope between the 1960’s and as recently as 2003. The families Macrouridae 

(grenadiers or rattails), Ophidiidae (cuskeels), and Alepocephalidae (slickheads) dominated the 

samples (Rowe and Kennicutt, 2009). Analysis of the data suggested an upper slope assemblage 

between 1,033 and 2,575 ft (315 and 785 m), a mid-slope assemblage between 2,251 and 4,491 ft 

(686 and 1,369 m), and a deep assemblage between 5,030 and 10,089 ft (1,533 and 3,075 m) 

(Rowe and Kennicutt, 2009). Shelf edge and upper slope species include tilefish (Lopholatilus 

chamaeleonticeps) and snowy grouper (Epinephelus niveatus).

Ichthyoplankton

Most fishes inhabiting the GOM, whether benthic or pelagic as adults, have pelagic larval 

stages. For the duration of this stage, these eggs and larvae become part of the planktonic 

community. Variability in survival and transport of pelagic larval stages is thought to be an important 

determinant of future year-class strength in adult populations of fishes and invertebrates

(Underwood and Fairweather, 1989; Doherty and Fowler, 1994). In general, the distribution of fish 

larvae depends on the spawning behavior of adults, hydrographic structure and transport at a variety 

of scales, duration of the pelagic period, behavior of larvae, larval mortality, and growth (Leis, 1991). 

Larval fishes are highly dependent on zooplankton until they can feed on larger prey.

Two important hydrographic features in the GOM are the Mississippi River discharge plume 

and the Loop Current. Combined with wind regimes in the region, these features strongly influence 

the transport and distribution of pelagic eggs and larvae. Water from the Mississippi River exits from 

several passes, delivering approximately one-third its volume to the Mississippi-Alabama shelf and 

two-thirds to the Texas-Louisiana shelf. The convergence and mixing of this many plumes is 

associated with continually reforming turbidity fronts and an accumulation of larvae at the plume 

boundary (Wiseman and Sturges, 1999). Planktonic eggs and larvae also become concentrated at 

the frontal boundaries of the Loop Current, shed rings, and gyres. Entrained Sargassum provides 

nursery habitat and refuge for many of these early life stage fish, and upwelling at the edges of the 

Loop Current and rings delivers nutrient-enriched waters to the surface, increasing primary 

production. Frontal waters of both the river plume and eddy boundaries provide feeding and growth 

opportunities for larvae.

Managed Species

For purposes of this analysis, managed species are those identified in a fishery management 

plan by a regional fishery management council or as a federally managed species. These species 

are subject to monitoring and management regulations. Fish species currently managed in the GOM 

are listed in Table D-1 of the Essential Fish Habitat Assessment white paper (USDOI, BOEM, 

2016d). Detailed descriptions of species abundance, life histories, and habitat associations for all 

life history stages are presented in the “Generic Amendment for Essential Fish Habitat” by the 

GMFMC (1998) and updated in the “Essential Fish Habitat Generic Amendment 3” (GMFMC, 2005). 
Description of the Affected Environment and Impact Analysis 4-221

Information on federally managed species and EFH is provided in the Consolidated Atlantic Highly 

Migratory Species Fishery Management Plan and amendments. These fishes and invertebrates are 

included in the preceding categories and are considered in the respective analyses for impacts 

below. Increased susceptibility to potential impacts as a result of fishing pressures will be discussed 

in the “Cumulative Impacts” section below.

4.7.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts described in Chapter 3 and their 

potential effects on fish and invertebrate resources that would potentially result from a proposed 

action or the alternatives. This analysis applies to all considered alternatives. While the WPA is a 

smaller area with less projected activity than is proposed for the CPA/EPA (refer to Chapter 3), the 

distribution of fishes and invertebrate species is nonrandom and species are associated with habitat 

preferences. However, within the Gulf of Mexico, distribution of species may generally be even 

throughout their range of habitat within the planning areas. As such, the potential for impacts to 

populations is independent of the planning area(s) analyzed. Differences in the specific populations 

potentially exposed to impact-producing factors and the potential impacts may be more easily 

estimated as specific sites and activities become known. Therefore, because of the diversity and 

distribution of species in the Area of Interest, the level of impacts would be the same for Alternatives 

A, B, C, and D. However, Alternative E would have no impacts as a proposed action would not be 

implemented; therefore, the only impacts would be those associated with the continuing effects from 

past lease sales and non-OCS oil- and gas-related activities. Following this environmental 

consequences chapter, there will be a summary of the potential impacts as they relate to the action 

alternatives.

4.7.2.1 Routine Activities

Routine OCS oil- and gas-related activities that take place on the OCS as a result of a 

proposed action and that produce sound, disturb the seafloor, or otherwise modify the habitat, could 

impact fish and invertebrate resources. A full list of impact-producing factors and scenarios for 

routine activities can be found in Chapter 3.1. 

Anthropogenic Sound

Natural background noise in a marine environment is the result of physical processes (i.e., 

wind, wave action, tidal movement, and geological activity) and bioacoustic signals (Wysocki and 

Ladich, 2005; Hildebrand, 2009; Radford et al., 2010; Ladich, 2013). Acoustic signaling in the 

marine environment is extremely efficient, so marine species have evolved several mechanisms for 

producing and receiving sound. Important sound-mediated behaviors can include spawning 

aggregations, larval settlement, territorial disputes, and predator-prey detection (Radford et al., 2010 

and 2014; Slabbekoorn et al., 2010). Despite the growing body of information on fishes, there is 

comparatively little information available on sound detection and sound-mediated behaviors for 

marine invertebrates (Mooney et al., 2012; Normandeau Associates, 2012; de Soto et al., 2013; 
4-222 Gulf of Mexico Multisale EIS

Popper et al., 2014; Samson et al., 2014). The diversity of marine fishes and invertebrates suggests 

the small number of studied species may not be representative of the full range of auditory sensory 

mechanisms and hearing capabilities. Therefore, caution was used in extrapolating potential 

impacts to fishes and invertebrate resources from documented behavioral responses and 

physiological impacts resulting from exposure to anthropogenic sound sources. For purposes of this 

analysis, it was deemed reasonable to use observed results as an indication of the types of impacts 

that may occur as a result of expected discrete and cumulative exposures to anthropogenic sound 

produced by routine OCS oil- and gas-related activities.

All routine OCS oil- and gas-related activities have some element of sound generation. 

Common sound sources include propeller cavitation, rotating machinery, and reciprocating 

machinery, which are associated with routine OCS oil- and gas-related activities such as vessel 

traffic, drilling, construction, and oil and gas production, processing, and transport. Sound 

introduced into the marine environment as a result of human activities has the potential to affect 

marine organisms by stimulating behavioral response, masking biologically important signals, 

causing temporary or permanent hearing loss (Popper et al., 2005; Popper et al., 2014), or causing 

physiological injury (e.g., barotrauma) resulting in mortality (Popper and Hastings, 2009). The 

potential for anthropogenic sound to affect any individual organism is dependent on the proximity to 

the source, signal characteristics, received peak pressures relative to the static pressure, cumulative 

sound exposure, species, motivation, and the receiver’s prior experience. In addition, environmental 

conditions (e.g., temperature, water depth, and substrate) affect sound speed, propagation paths, 

and attenuation, resulting in temporal and spatial variations in the received signal for organisms 

throughout the ensonified area (Hildebrand, 2009).

Sound detection capabilities among fishes vary. All fishes are able to detect low-frequency 

particle motion at short ranges by means of the otolith and lateral line organs (Popper et al., 2003). 

Detection of the particle velocity and the ability to determine the position of the source is only 

possible over distances of 1-2 body lengths, but it is important for orientation in flowing water and 

maneuvering in close proximity to other organisms (Popper et al., 2014). Species with a swim 

bladder and accessory structure close to or in contact with the inner ear have increased hearing 

sensitivity and a wider range of detectable frequencies than do fishes with a swim bladder only or 

fishes with no gas-filled structure (Popper et al., 2003). For most fish species, it is reasonable to 

assume hearing sensitivity to frequencies below 500 Hertz (Hz) (Popper et al., 2003 and 2014; 

Popper and Hastings, 2009; Slabbekoorn et al., 2010; Radford et al., 2014). Ambient noise may be 

divided into three general frequency bands (i.e., low, medium, and high), each dominated by 

different sound sources (Hildebrand, 2009). The band of greatest interest to this analysis, lowfrequency sound (30-500 Hz), has come to be dominated by anthropogenic sources and includes 

the frequencies most likely to be detected by most fish species. For example, the noise generated 

by large vessel traffic typically results from propeller cavitation and falls within 40-150 Hz 

(Hildebrand, 2009; McKenna et al., 2012). This range is similar to that of fish vocalizations and 

hearing, and could result in a masking effect.
Description of the Affected Environment and Impact Analysis 4-223

Masking occurs when background noise increases the threshold for a sound to be detected; 

masking can be partial or complete. If detection thresholds are raised for biologically relevant 

signals, there is a potential for increased predation, reduced foraging success, reduced reproductive 

success, or other effects. However, fish hearing and sound production may be adapted to a noisy 

environment (Wysocki and Ladich, 2005). There is evidence that fishes are able to efficiently 

discriminate between signals, extracting important sounds from background noise (Popper et al., 

2003; Wysocki and Ladich, 2005). Sophisticated sound processing capabilities and filtering by the 

sound sensing organs essentially narrows the band of masking frequencies, potentially decreasing 

masking effects. In addition, the low-frequency sounds of interest propagate over very long 

distances in deep water, but these frequencies are quickly lost in water depths between 1⁄2 and 1⁄4 the 

wavelength (Ladich, 2013). This would suggest that the potential for a masking effect from lowfrequency noise on behaviors occurring in shallow coastal waters may be reduced by the receiver’s 

distance from sound sources, such as busy ports or construction activities.

Pulsed sounds generated by OCS oil- and gas-related activities (e.g., impact-driven piles 

and airguns) can potentially cause behavioral response, reduce hearing sensitivity, or result in 

physiological injury to fishes and invertebrate resources. Impact pile-driving during OCS 

construction and on-lease seismic activity are both temporally and spatially limited activities. The 

effects of these sound-producing activities would extend only to communities of fishes and 

invertebrates within a relatively small area. Benthic fishes and invertebrates could receive sound 

waves propagated through the water and sound waves propagated through the substrate. However, 

Wardle et al. (2001) found that, although fishes and invertebrates associated with a reef exhibited a 

brief startle response when exposed to pulsed low-frequency signals, disruption of diurnal patterns 

was not observed. Fishes disturbed by the noise were observed to resume their previous activity 

within 1-2 seconds and only exhibited flight response if the airguns were visible when discharged 

(Wardle et al., 2001). Other studies of fishes exposed to pulsed anthropogenic sound signals in 

natural environments have produced a wide range of results suggesting that species, experience, 

and motivation are very important factors, and indicating that habituation may occur (Engås et al., 

1996; Løkkeborg et al., 2012; Popper et al., 2014). Organisms in close proximity to a pulsed sound 

source are at increased risk of barotrauma. A signal with a very rapid rise and peak pressures that 

vary substantially from the static pressure at the receiver’s location can cause physiological injury or 

mortality (Popper et al., 2014). However, the range at which physiological injury may occur is short 

(<10 m; <33 ft) and, given fish avoidance behavior, the potential for widespread impacts to 

populations as a result of physiological injury is negligible. 

Despite the importance of many sound-mediated behaviors and the potential biological costs 

associated with behavioral response to anthropogenic sounds, many environmental and biological 

factors limit potential exposure and the effects that OCS oil- and gas-related sounds have on fishes 

and invertebrate resources. The overall impact to fishes and invertebrate resources due to 

anthropogenic sound introduced into the marine environment by OCS oil- and gas-related routine 

activities is expected to be minor. 
4-224 Gulf of Mexico Multisale EIS

Bottom-Disturbing Activities

For the purpose of this analysis, bottom-disturbing activities are distinguished from habitat 

modification by the relatively short period of time over which disturbances occur. Anchoring, drilling, 

trenching, pipe-laying, and structure emplacement are examples of OCS oil- and gas-related 

activities that disturb the seafloor. The specific activity, ocean currents, and water depth can affect 

the extent of the water column and seafloor disturbance, and the magnitude of the effect. For 

example, drilling an exploratory well produces approximately 2,000 metric tons (2,205 tons) of 

combined drilling fluid and cuttings, though the total mass may vary widely for different wells (Neff, 

2005). Cuttings discharged at the surface tend to disperse in the water column and are distributed 

at low concentrations (CSA, 2004b). In deep water, cuttings discharged at the sea surface may 

spread 3,280 ft (1,000 m) from the source, with the majority of the sediment deposited within 820 ft 

(250 m) of the well (CSA, 2006). Drilling mud plumes may be visible 0.6 mi (1 km) from the

discharge point, but the plumes rapidly become diluted (Shinn et al., 1980; Hudson et al., 1982; Neff, 

2005). Cuttings shunted to the seafloor form piles concentrated within a smaller area than that 

affected by sediments discharged at the sea surface (Neff, 2005). Emplacement of infrastructure

(i.e., pipelines, platforms, and subsea systems) can also displace large volumes of sediment, 

resulting in increased turbidity and sedimentation (Chapter 3.1.3.3).

Turbidity and sedimentation resulting from routine OCS oil- and gas-related activities are 

short term and have localized effects (Chapter 3.1.3.3.3). The potential impacts to fishes and 

invertebrates (e.g., reduced feeding efficiency, decreased predator avoidance, and behavioral 

responses) may be related to species-specific behaviors and habitat preference (Minello et al., 1987; 

Benfield and Minello, 1996; Chesney et al., 2000; de Robertis et al., 2003; Jönsson et al., 2013; Lunt 

and Smee, 2014). Mobile fishes and invertebrates are expected to avoid the heaviest sedimentation 

and highest suspended sediment loads within 33 ft (10 m) of a disturbance. Icthyoplankton cannot 

avoid sediment plumes at or near the surface and may be exposed for longer durations than adults. 

However, evidence suggesting increased turbidity, which may reduce hatching success or delay 

larval development, is limited, and other studies have shown larval foraging success and growth may 

benefit from nutrient-rich plumes (Wenger et al., 2014; Gray et al., 2012). Coastal fishes and 

invertebrate species adapted to turbid environments, such as shallow bays, estuaries, and coastal 

habitat influenced by the Mississippi River plume, may be less affected by increased turbidity than 

species typically inhabiting less turbid environments.

Due to a combination of the spatiotemporally limited nature of suspended sediment plumes 

resulting from bottom-disturbing activities, avoidance behaviors, and a range of tolerances for 

various environmental conditions, the overall impact to fishes and invertebrate resources as a result 

of bottom disturbances associated with OCS oil- and gas-related routine activities is expected to be 

negligible. 

Habitat Modification

For purposes of this analysis, the installation of platforms, pipelines, and subsea systems, or 

the construction of other facilities within a marine environment constitutes habitat modification. 
Description of the Affected Environment and Impact Analysis 4-225

Although these structures are temporary (refer to Chapter 3.1.6, Decommissioning and Removal 

Operations; Chapter 3.1.6.2, Artificial Reefs; and Chapter 3.3.2.1.2, Artificial Reefs, for more 

information), the operational life is long term and may impact the distribution of species in an area 

(Carr and Hixon, 1997; Gallaway et al., 2009; Shipp and Bortone, 2009). It is generally assumed 

that artificial structures serve as both fish-attracting and production-enhancing devices, depending 

upon the species (Carr and Hixon, 1997; Gallaway et al., 2009; Shipp and Bortone, 2009). The 

resulting assemblages frequently include commercially and recreationally valuable coastal and 

oceanic fishes. The well-known association with OCS oil- and gas-related structures attracts 

fishermen targeting these species and may subject some fishes to locally increased fishing pressure 

(Dance et al., 2011; Addis et al., 2013). However, infrastructure or pipeline removal also impacts 

fishes and invertebrates associated with the substrate. Removal of the structure is necessary to 

restore the seafloor to the original soft bottom habitat, but it would likely result in an altered 

community as the restored site is recolonized. The removal of hard substrate may result in 

community-level changes, such as an overall reduction in species diversity of epifaunal organisms, 

fishes, and invertebrates (Schroeder and Love, 2004).

Fish mortality can occur as a result of decommissioning operations using explosive 

severance methods; however, a study of the associated mortality for three commercially important 

fishes indicated that the level of explosive severance activity in the GOM did not significantly alter 

stock assessments (Gitschlag et al., 2001). To account for inherent variations in species 

composition and abundance among platforms (e.g., Stanley and Wilson, 1997; Gitschlag et al., 

2001; Stanley and Wilson, 2000; Wilson et al., 2003), mortality estimates were doubled and stock 

estimates were recalculated. Although the study was limited and cannot be directly applied to all 

species or habitats, it is reasonable to assume that other represented fish populations would 

respond similarly. Impacts to sessile benthic organisms (e.g., barnacles and bivalves) and many 

mobile invertebrates (e.g., shrimp and crabs) that do not possess swim bladders are expected to be 

minimal (Keevin and Hempen, 1997; Schroeder and Love, 2004) because it is typically the rapid 

expansion and contraction of gas-filled spaces in response to pressure changes that results in the 

greatest physiological injury. Larvae and small juvenile fishes have been found to be more 

susceptible to injury from shock waves than large juveniles or adults (Govoni et al., 2008). At the 

projected rate of removal, these activities are not expected to have a substantial negative impact on 

stocks of managed fishes or other fishes and invertebrates associated with OCS oil- and gas-related 

infrastructure. 

Some structures may be converted to artificial reefs. If portions of a platform were permitted 

to be reefed in place, the hard substrate and encrusting communities would remain part of the 

benthic habitat. The diversity of the community would change due to the reduced presence in the 

water column, but some associated fish species would be expected to continue use of the structure. 

Structures removed and redeployed as artificial reef substrate at another location may support 

substantially different communities, depending on the environmental characteristics of the reef site 

and other factors. The plugging of wells and other decommissioning activities that disturb the 

seafloor would impact benthic communities as discussed above.
4-226 Gulf of Mexico Multisale EIS

Some ichthyoplankton studies have been conducted, focusing specifically on the influence of 

offshore platforms. The first of these projects investigated the potential role of platforms as nursery 

habitat for larvae or refugia for postlarval and juvenile fish (Hernandez et al., 2001). A follow-up 

study by Shaw et al. (2002) used data collected at several platforms both east and west of the 

Mississippi River Delta to examine the significance of platforms to larval and juvenile fishes. Both 

Hernandez et al. (2001) and Shaw et al. (2002) found highest taxonomic richness and diversity at 

mid-shelf platforms. Results indicated the distribution of larval and juvenile life stages is influenced 

by across-shelf gradients of increasing depth, similar to the distribution of adult fishes. Differences 

observed in the abundance of certain taxa in larval and juvenile fish assemblages across longitudinal 

gradients may reflect differences in the hydrographic conditions and/or habitat availability (Shaw 

et al., 2002). These results indicate the predominant factors influencing the distribution of larvae and 

juvenile life stages are environmental conditions and the distribution of adult conspecifics. 

Therefore, emplacement and/or removal of OCS oil- and gas-related infrastructure as the result of a 

proposed action is expected to have a negligible impact on the distribution or abundance of 

ichthyoplankton.

Although fish and invertebrate resources may be affected by habitat modifications due to 

routine OCS oil- and gas-related activities, there is no evidence suggesting that population-level 

impacts would occur as a result of a proposed activity. Due to the localized nature of the effects and 

limited number of structure installations and removals anticipated, impacts to fishes and invertebrate 

resources as a result of routine OCS oil- and gas-related activities are expected to range from 

negligible for most species to minor for species most commonly associated with OCS oil- and gasrelated platforms (e.g., sharpnose puffer [Canthigaster rostrate], gray triggerfish [Balistes capriscus], 

great barracuda [Sphyraena barracuda], and red snapper).

4.7.2.2 Accidental Events

Accidental events resulting in a release of oil or other contaminants (“spills”) could adversely 

affect fish and invertebrate resources. Although an unlikely occurrence, a subsea loss of well control

would also suspend large amounts of sediment. For the reasons stated above (“Bottom-Disturbing 

Activities”), the potential effects of suspended sediments would be negligible. This section will 

address the potential effects to fishes and invertebrate resources resulting from direct and indirect 

exposure to spilled oil. Oil spills, historic trends, the characteristics of oil, and factors affecting the 

fate of oil released into the marine environment are discussed in Chapter 3.2.1, and the potential 

effects on water quality are analyzed in Chapter 4.2 (Water Quality).

The effects of spills in open waters of the OCS proximate to mobile adult fishes would likely 

be sublethal; potential effects would be reduced because adult fish have the ability to avoid adverse 

conditions, metabolize hydrocarbons, and excrete metabolites and parent compounds. However, 

dispersal and emulsification of spilled oil can increase bioavailability to fishes and invertebrates 

throughout the water column. Some filter feeders, such as Gulf menhaden, may have an increased 

risk of exposure due to the likelihood of ingesting high levels of dispersed oil. Increased 

contaminant exposure could result in a higher incidence of chronic sublethal impacts (Millemann 
Description of the Affected Environment and Impact Analysis 4-227

et al., 2015). Similarly, adsorption of oil to suspended particulate matter and subsequent 

sedimentation increases the potential for chronic exposure of demersal fishes and benthic 

invertebrates to oil (Murawski et al., 2014; Baguley et al., 2015; Snyder et al., 2015). Long-term 

impacts to fish and invertebrate populations in the GOM have not been identified, but studies 

suggest short-term impacts, including increased metabolic costs, immunosuppression, and 

histological lesions (Carls et al., 1998; Brewton et al., 2013). As a result of these effects, fitness and 

productivity of affected individuals may be decreased.

Oil floating on the surface could directly contact ichthyoplankton found at or near the surface, 

coating eggs and larvae. Most ichthyoplankton would be unable to avoid spills and the affected 

individuals may be at risk of death, delayed development, abnormalities, endocrine disruption, or 

other effects, resulting in decreased fitness and reduced survival rates (Incardona et al., 2014; 

Mager et al., 2014; Brown-Peterson et al., 2015; Snyder et al., 2015). In general, early life stages 

are more sensitive to acute oil exposure than adults, but some research indicates that embryos, 

depending on the developmental stage, may be less sensitive to acute exposure than larval stages 

(Fucik et al., 1995). Spills reaching estuarine habitat or overlapping spatiotemporally with a 

spawning event have the greatest potential for affecting the early life stages of fishes and 

invertebrates.

Effects from an accidental event would be expected to be localized; accidental spills have 

historically been small and are low-probability events (Tables 3-12 and 3-17). Most fishes and 

invertebrates in the GOM are broadly distributed throughout one or more regions of the GOM and, 

typically, only a small portion of a population would be impacted (McEachran, 2009). Studies 

indicate that the impacts of previous accidental spills have not resulted in population-level effects 

(Fodrie and Heck, 2011; Moody et al., 2013; Rooker et al., 2013; Murawski et al., 2014; Fry and 

Anderson, 2014). However, long-term impacts could be masked by many factors (e.g., natural 

population variability, natural and anthropogenic disturbances, and compensatory processes) and 

may not be observed for several years (Fodrie et al., 2014). Therefore, the overall impact to fishes 

and invertebrate resources due to reasonably foreseeable accidental spills resulting from routine 

OCS oil- and gas-related activities is expected to be negligible. 

4.7.2.3 Cumulative Impacts

The OCS oil- and gas-related activities resulting from a lease sale are assumed to occur 

over a period of 50 years. However, available information is insufficient to conduct an analysis of 

impact-producing factors potentially affecting fish and invertebrate resources over the same period. 

The unknown influence of changing environmental, biological, and anthropogenic factors over such 

an extended period could exceed that of analyzed impact-producing factors. Therefore, this section 

assumes an analysis of reasonably foreseeable cumulative impacts to encompass a period of 

approximately 20 years. This cumulative analysis considers the effects on fishes and invertebrate 

resources of the Gulf of Mexico as a result of the OCS Program, State oil and gas activity, 

recreational and commercial fishing (Chapters 4.11 and 4.10, respectively), and habitat availability. 

The incremental impact of a single proposed lease sale combines the effects of the associated 
4-228 Gulf of Mexico Multisale EIS

routine activities and accidental events described in Chapters 4.7.2.1 and 4.7.2.2, respectively. The 

expected incremental contributions (Table 4-15) are incorporated into this cumulative analysis. 

Potential degradation of specific habitats is analyzed in Chapters 4.3 (Coastal Habitats), 

4.4 (Deepwater Benthic Communities), 4.5 (Sargassum and Associated Communities), and 4.6 (Live 

Bottom Habitats). The direct and/or indirect impacts from cumulative OCS oil- and gas-related and 

non-OCS oil- and gas-related activities on essential fish habitat are considered and summarized in 

the Essential Fish Habitat Assessment white paper (USDOI, BOEM, 2016d).

OCS Oil- and Gas-Related Impacts

As discussed in the analysis of routine activities, OCS oil- and gas-related activities produce 

some level of anthropogenic sound, though signal characteristics vary widely. Geological and 

geophysical surveys, construction of new facilities, and decommissioning are episodic acoustic 

events and do not contribute to long-term changes in the soundscape. The OCS oil- and gas-related 

support vessel traffic, drilling, production facilities, and other sources of continuous sounds 

contribute to a chronic increase in background noise, with varying areas of effect that may be 

influenced by the sound level, frequencies, and environmental factors (Hildebrand, 2009; 

Slabbekoorn et al., 2010; McKenna et al., 2012). These sources have a low potential for causing 

physiological injury or injuring hearing in fishes and invertebrates (Popper et al., 2014). However, 

continuous sounds have an increased potential for masking biologically relevant sounds than do 

pulsed signals. The potential effects of masking on fishes and invertebrates is difficult to assess in 

the natural setting for communities and populations of species, but evidence indicates that the 

increase to background noise as a result of the OCS Program would be relatively minor. Therefore, 

it is expected that the cumulative impact to fishes and invertebrate resources in the GOM would be 

minor and would not extend beyond localized disturbances or behavioral modification. The 

incremental impact of a single proposed lease sale would be minor. 

Sediment suspended by bottom-disturbing activities settles rapidly to the seafloor. Impacts 

from individual events are temporary, highly localized, and expected to impact small numbers of 

organisms. In nearshore and estuarine waters, the effects of temporarily increased turbidity would 

be indistinguishable from background conditions. Bottom-disturbing activities in outer-shelf and 

oceanic waters may temporarily affect fishes and invertebrates in the water column or bury sessile 

benthic organisms near the disturbance. The cumulative contribution to adverse impacts on these 

resources would be negligible due to the transient nature of the disturbance and the limited area 

affected. The incremental impact of a single proposed lease sale would be negligible. 

Cumulative habitat modification as a result of OCS oil- and gas-related activities is spatially 

extensive and long term in nature. It has been hypothesized that the network of OCS oil- and gasrelated infrastructure has resulted in changes in the distribution of some species (Shipp and Bortone, 

2009; Gallaway et al., 2009). However, the total contribution of OCS oil- and gas-related 

infrastructure to hard substrate in the Gulf is small and is projected to decrease throughout the 

period covered by this analysis (Gallaway et al., 2009). Exceptions to the removal requirement may 

be permitted under specific circumstances; for more information, refer to Chapters 3.1.6.2 (Artificial 
Description of the Affected Environment and Impact Analysis 4-229

Reefs) and 3.3.2.1.2 (Artificial Reefs). The cumulative impact of OCS oil- and gas-related habitat 

modification on fishes and invertebrate resources may be extensive for some species; therefore, 

cumulative impacts may range from negligible for most species to moderate for those species 

associated with OCS oil- and gas-related platforms (i.e., distribution and abundance may vary from 

historical values). The incremental impact of a single lease sale would be negligible to minor. 

Non-OCS Oil- and Gas-Related Activities

Commercial shipping is the greatest anthropogenic source of low-frequency sound in the 

marine environment and, combined with many other sources (e.g., State oil- and gas-related 

activities, coastal construction, and recreational boating), contributes to increased background noise

levels (Hildebrand, 2009; McKenna et al., 2012; Hawkins et al., 2014). As a result of increasing

background noise, fishes and invertebrates may modify behaviors and biologically relevant sounds 

could be masked, but the effects are difficult to assess in the natural setting. Marine organisms 

evolved in a noisy environment and available information suggests that at least some fishes and 

invertebrates may have the capacity to adapt to increasing noise levels (Wardle et al., 2001; 

Wysocki and Ladich, 2005; Purser and Radford, 2011; Radford et al., 2014). However, even 

organisms adapted to increasing background noise could incur consequences from remaining in an 

environment continuously exposed to sound energy from anthropogenic sources. Potential effects 

would vary among species and across a range of environmental factors but may include reduced 

hatching rates, delayed development, or decreased reproductive potential (Slabbekoorn et al., 2010; 

Hawkins et al., 2014). The overall contribution of non-OCS oil- and gas-related anthropogenic 

sound sources to increasing background noise levels in the marine environment is expected to 

moderately impact fishes and invertebrate resources because increased background noise levels 

affect broad areas and can be reasonably assumed to have limited population-level impacts, but 

they would not be expected to result in a long-term decline in population.

The NMFS is responsible for implementing fisheries regulations and managing commercial 

and recreational fisheries, with advice from the regional fisheries management councils. 

Commercial and recreational fishing have been a factor in the decline of several fish populations in 

the GOM (Shipp, 1999; USDOC, NMFS, 2015a; NRC, 2014). Although several stocks are rebuilding 

or have been rebuilt, certain fishing practices and overfishing can have long-term effects on target 

species and the ecosystem. For example, the structure of a rebuilt stock may differ from historic 

demographics, resulting in a less resilient population, or habitat could be altered such that species 

diversity and abundance are affected (Wells et al., 2008; NRC, 2014; Pusceddu et al., 2014; Secor 

et al., 2014). The cumulative impact of long-term, large-scale fisheries activity on fishes and 

invertebrate resources in the GOM is not known, but NMFS has determined that assessed fish 

stocks are predominantly healthy (USDOC, NMFS, 2015a). Thus, it is expected that impacts to 

fishes and invertebrate resources as a result of commercial and recreational fisheries would range 

from negligible for most nontargeted species to moderate for species that are overfished or 

experiencing overfishing (e.g., hogfish spp., gray triggerfish, and greater amber jack [Seriola 

dumerili]).
4-230 Gulf of Mexico Multisale EIS

The conversion or modification of wetlands as a result of agricultural, residential, and 

commercial development in the GOM has been substantial (USEPA, 2012b; Greene et al., 2014). 

The trend for coastal development is projected to continue into the future, although at a slower rate 

because of regulatory pressures (refer to Chapter 4.3, Coastal Habitats, for detailed information on 

these habitats, potential impacts, and mitigations). The conversion of habitat from one form to 

another (e.g., wetlands to open water) would typically result in community-level changes in 

biodiversity and abundance compared with communities in unmodified habitat (Lowe and Peterson, 

2014; USDOC, NMFS, 2010a). Although changes to habitat may benefit some species while 

adversely impacting others, it is generally accepted that the quality (i.e., the ecological services 

provided) of modified habitat is not equivalent to natural habitat (Peterson and Lowe, 2009; 

Scyphers et al., 2015). Therefore, the continued loss or modification of wetlands could ultimately 

result in decreased recruitment for some estuarine-dependent species, adversely impacting stocks 

within the region (Levin and Stunz, 2005; Jordan et al., 2012). The current lack of a meaningful 

baseline makes it extremely difficult to estimate cumulative impacts to fishes and invertebrate 

resources at a regional scale. However, coastal zone management efforts increasingly incorporate 

the responses of fishes and invertebrates into analyses of development activities (Peterson and 

Lowe, 2009; Greene et al., 2014). The Federal, State, and local agencies jointly responsible for 

managing estuarine habitats, permitting development, and mitigating impacts ensure that 

sustainable development practices are implemented. Therefore, the cumulative adverse impact of 

coastal development on fishes and invertebrate resources is expected to be minor. 

Additional pressures potentially contributing to cumulative effects on fishes and invertebrate 

resources in the GOM include increasing invasive species populations and climate change. These 

factors are currently negligible but could have increasingly substantial impacts in the future. Invasive 

species, such as the lionfish, have the potential to out-compete and displace some indigenous 

species of ecological, commercial, and/or recreational importance (Morris and Akin, 2009; Dahl and 

Patterson, 2014; Raymond et al., 2014). Although severe weather events are part of the natural 

environment and are not considered in an analysis of impact-producing factors, changing conditions 

that alter the frequency and/or severity of weather events or that accelerate sea-level rise could 

impact fishes and invertebrate resources in an unforeseen manner. A review of climate change is 

presented in Chapter 4.2.1 of the Five-Year Program EIS (USDOI, BOEM, 2016b).

The cumulative effect of combined past, present, and reasonably foreseeable future OCS oiland gas-related activities and non-OCS oil- and gas-related activities on fishes and invertebrate 

resources of the Gulf of Mexico is expected to vary spatiotemporally. The incremental contribution 

of OCS oil- and gas-related activities to the combined cumulative impacts is generally minor in 

comparison with all other human activities affecting the resources. Impacts to fish and invertebrate 

populations are expected to be in proportion to the fraction of a population exposed to an impactproducing factor. Therefore, OCS oil- and gas-related habitat modification is likely to have a greater 

impact than other oil- and gas-related impact-producing factors of a more limited scale and duration. 

However, impacts are not universally adverse and some habitat modification may benefit particular 

species or communities. Commercial and recreational fishing are expected to have the greatest 

direct impact on fishes and invertebrate resources. Although NMFS manages fisheries, populations 
Description of the Affected Environment and Impact Analysis 4-231

are affected by many biological and environmental factors. Fluctuations in populations of fisheriesaffected species are expected. Increased background noise levels due to anthropogenic sources, 

such as commercial shipping, are also likely to affect deep waters of the GOM (Hildebrand, 2009). 

Although the effects are currently unknown, no impacts to fish and invertebrate populations in the 

GOM have been quantified. International efforts to develop and implement ship-quieting 

technologies may mitigate future increases in shipping capacity. As a result of these impactproducing factors, the overall cumulative impact on fishes and invertebrate resources may range 

from minor to moderate for different species throughout the period analyzed.

4.7.2.4 Incomplete or Unavailable Information

BOEM identified incomplete or unavailable information related to impacts to fishes and 

invertebrate resources resulting from OCS oil- and gas-related activities and non-OCS oil- and 

gas-related activities in the GOM. Anthropogenic sound and habitat modification directly or indirectly 

affect large areas of the GOM and potentially impact thousands of species. However, the response 

of individuals, groups of conspecifics (members of the same species), and communities are highly 

variable and inconsistent. In addition, BOEM recognizes that there is incomplete information with 

respect to potential long-term effects resulting from exposure to spilled oil. Although additional 

information on these impact-producing factors may be relevant to the evaluation of impacts to fishes 

and invertebrate resources, BOEM has determined that the incomplete information is not essential to 

a reasoned choice among alternatives. Analyses of routine activities, accidental events, and 

cumulative impacts drew upon the most current and best available research to assess the potential 

effects on many species and habitats. The findings collectively indicate that impacts are likely, but 

limited, and are not expected to induce a population-level response. BOEM recognizes the potential 

that populations with spatially limited distributions or increased sensitivity to an impact-producing 

factor may be more severely impacted than current research suggests. However, sufficient data to 

conduct a thorough assessment of all potentially affected species are not available or obtainable 

within the timeline contemplated in the NEPA analysis of this Multisale EIS. BOEM used the best 

available science to determine the range of reasonably foreseeable impacts and applied accepted 

scientific methodologies to integrate existing information and extrapolate potential outcomes in 

completing this analysis and formulating the conclusions presented here.

4.7.2.5 Alternatives A, B, C, and D

With respect to fishes and invertebrate resources, the effects associated with selection of 

any of the proposed action alternatives would be equivalent because of the diversity and distribution 

of fish and invertebrate species throughout the potential area of interest. The preceding analyses 

assumed a nonrandom distribution of species (i.e., distribution is associated with habitat preference 

and habitat availability) and considered impacts to fishes and invertebrate resources occurring in a 

wide range of habitats across all planning areas. While the WPA is a smaller area with less 

projected activity than is proposed for the CPA/EPA (refer to Chapter 3), the distribution of fishes 

and invertebrate species is nonrandom and generally even throughout their range of habitat within 

the planning areas. As such, the potential for impacts to populations is independent of the planning 

area(s) analyzed. Differences in the specific populations potentially exposed to impact-producing 
4-232 Gulf of Mexico Multisale EIS

factors and the potential impacts may be more easily estimated as specific sites and activities 

become known. Therefore, at a planning area scale, it is expected that a similar mix of species 

would be exposed to the analyzed impact-producing factors, regardless of the specific action 

alternative selected. The analysis of routine activities and accidental events indicates that the 

incremental contribution to the overall cumulative impacts on fishes and invertebrate resources as a 

result of a single proposed lease sale would be minor. The activities proposed under Alternatives A, 

B, C, and D would directly impact fishes and invertebrate resources within the GOM and would 

contribute incrementally to the cumulative effects on these resources. Routine activities, excluding 

infrastructure emplacement, would be expected to have short-term and/or localized effects. The 

installation of OCS oil- and gas-related infrastructure constitutes a long-term modification of the local 

habitat. Individually, these modifications have small-scale (e.g., community-level) effects on the 

distribution and abundance of species; cumulatively, OCS oil- and gas-related infrastructure is 

hypothesized to have moderately impacted the distribution of some fishes and invertebrates, 

exceeding natural variations. Although this effect is not necessarily adverse and infrastructure is 

expected to be decommissioned and sites restored to natural habitat, the cumulative impact over the 

life of the OCS Program is spatiotemporally extensive with species-specific effects. Accidental spills 

are considered low-probability events, but they have the potential to produce localized impacts on 

fishes and invertebrate resources if coinciding with a spawning event. Mobile adults are expected to 

avoid adverse conditions, limiting exposure to spilled oil. The cumulative, long-term effects of 

exposure to oil are unknown, but available information suggests that the effects have been minor. 

The cumulative effects of habitat loss and increasing background noise levels are unknown, but the 

OCS oil- and gas-related contribution is small, relative to non-OCS oil- and gas-related impactproducing factors. Therefore, the analysis of routine OCS oil- and gas-related activities, accidental 

events, and the cumulative impacts of OCS oil- and gas-related and non-OCS oil- and gas-related 

activities indicates the expected overall impact to fishes and invertebrate resources, depending upon

the IPF and the affected species, would range from negligible to moderate for the period analyzed. 

For example, muds and cuttings discharged at the surface for a well drilled at a water depth of 

5,000-ft (1,524 m) would have a negligible impact on coastal species, such as menhaden, whereas a 

small spill in coastal waters and subsequent response activities could disrupt a spawning event or 

temporarily displace coastal fishes from the affected area (minor). Moderate impacts would only be 

expected if impact-producing factors affected habitat or populations to an extent that would be 

expected to exceed natural variations in population abundance or distribution but not result in a longterm decline.

4.7.2.6 Alternative E—No Action

Under Alternative E impacts on fishes and invertebrate resources within the Gulf of Mexico 

would be none. However, cumulative impacts would be unchanged from the conclusions reached 

for the other alternatives.

4.8 BIRDS

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

with a GOM proposed action and a proposed action’s incremental contribution to the cumulative 
Description of the Affected Environment and Impact Analysis 4-233

impacts to coastal and migratory birds are presented in this chapter. The approach of the analysis is 

to focus on the potential impact-producing factors from OCS oil- and gas-related routine activities 

(i.e., exploration, development, and production), as well as accidental events and cumulative 

impacts, and to define the impact levels for each impact-producing factor. The impact-producing 

factors considered and analyzed include discharges and wastes, noise, platform severance with 

explosives, geophysical surveys with airguns, platform presence and lighting, emergency air 

emissions, platform or pipeline oil spills, spill response, oil- and gas-related activities in State waters, 

the hypoxic “dead zone” of the Mississippi River, net coastal wetland gain or loss, urbanization, a 

large tanker spill, military activities, recreation, boat traffic, impacts on bird habitat, collisions with 

vehicles and buildings, predation by domestic cats, commercial fishing, climate change, and wetland 

subsidence. The potential magnitude of impact for each of these impact-producing factors is 

provided in Table 4-16 to help the reader quickly identify the level of potential impacts for each 

impact-producing factor. The impact-level definitions and the analyses supporting these conclusions 

are then discussed in detail in this chapter.

Impact-producing factors considered but not analyzed include obstruction lighting, which is 

under the jurisdiction of the USCG. Other impact-producing factors that were not analyzed because 

they do not apply to birds include geological ancillary activities, all onshore infrastructure

emplacement and presence, offshore platform emplacement, other commissioning activities, and 

onshore waste disposal. 

Seven species found in the area of interest are listed under the ESA, and BOEM has initiated 

formal consultation with FWS for those species. Those species have life histories that are similar to 

those of the birds covered in this chapter, but the cumulative impact could be greater. BOEM 

recognizes this, consults on these species, and requires mitigations that would decrease the 

potential for greater impacts due to small population size. For more information on the listed bird 

species, refer to Chapter 4.9.4 (Protected Birds).

Table 4-16. Birds Impact-Producing Factors That Are Reasonably Foreseeable.

Birds Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Impacts

Discharges and 

Wastes Negligible Negligible Negligible Negligible None

OCS Oil- and GasRelated Noise and 

Disturbance

Negligible Negligible Negligible Negligible None

Platform Severance 

and Rigs-to-Reefs Minor Minor Minor Minor None

Geophysical Surveys 

with Airguns Minor Minor Minor Minor None

Platform Presence 

and Lighting Minor Minor Minor Minor None
4-234 Gulf of Mexico Multisale EIS

Birds Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Accidental Impacts

Oil Spills Moderate Moderate Moderate Moderate None

Oil-Spill Response Minor Minor Minor Minor None

Emergency Air 

Emissions Minor Minor Minor Minor None

Cumulative Impacts

Incremental 

Contribution2 Moderate Moderate Moderate Moderate None

OCS Oil and Gas3 Moderate

Non-OCS Oil and 

Gas4 Major

1 The analysis supporting these conclusions are discussed in detail in the “Environmental Consequences” 

chapter below. Moderate impact levels could be possible but only if a large oil spill were to occur.

2 This impact level is the incremental contribution of a single proposed lease sale to all cumulative 

impacts in the GOM.

3 This impact level is the cumulative impacts of all past, present, and reasonably forseeable OCS oil- and 

gas-related activities in the GOM.

4 This impact level is the cumulative impacts of all past, present, and reasonably foreseeable activities in 

the GOM.

Impact-Level Definitions

Two concepts important in the impact-level definitions below are populations and population 

sizes. In ecology, a population is often defined as a group of individuals with similar genes (i.e., 

species and subspecies). Such a population lives in one or more natural geographic areas where its 

habitats are located. Human-made areas (e.g., the planning areas) are also important to the 

analysis. Natural areas overlap with the planning areas. Bird species described in this chapter are 

considered to have large populations and to be widely distributed. Flock size and population, 

mentioned below in the impact-level definitions, have ranges of impacts that can vary by bird 

species. Examples of flock sizes and population sizes are given in the “Description of the Affected 

Environment” chapter. Abundance, as used in this chapter, means the number or biomass (total 

weight) of a particular species in a general area (this definition is taken from Krebs [2009]). Chronic, 

as used in this chapter, means of indefinitely high frequency or of indefinitely long duration.

The impact-level definitions for birds are as follows:

• Negligible – Impacts would not affect a substantial abundance of birds. Impacts 

would especially not affect species with low abundances prior to impacts. 

Estimates of continued population viability, including predicted annual rates of 

recruitment or survival, would not change. Any impacts would be acute and 

reversible. Further, no injury to or mortality of a small number of individuals or a 

small flock would occur.
Description of the Affected Environment and Impact Analysis 4-235

• Minor – Impacts would not affect a substantial abundance of birds. Impacts 

would especially not affect species with low abundances prior to impacts. 

Estimates of continued population viability, including predicted annual rates of 

recruitment or survival, would not change. Additionally, one or both of the two 

following conditions must be met: (1) small numbers of individuals or small flocks 

of birds would experience chronic impact-producing factors and would be 

chronically disturbed or affected, resulting in chronic but reversible behavioral 

changes; and/or (2) one or more incidents would occur where small numbers of 

individuals or small flocks of birds would experience injury or mortality, but with 

no measurable impact on a population.

• Moderate – Impacts would affect a substantial abundance of birds. Estimates of 

continued population viability, including predicted annual rates of recruitment or 

survival, would not change. Additionally, one or both of the two following 

conditions must be met: (1) a large flock of birds (e.g., a shorebird flock of 500 or 

1,000 birds) would experience chronic impact-producing factors and would be 

chronically disturbed or affected, resulting in chronic behavioral changes or 

mortality over time; and/or (2) one or more incidents would occur where 

substantial numbers of individuals, including large flocks, would experience 

chronic behavior changes or mortality that would affect a large flock but with no 

measurable impact on a population.

• Major – Impacts would affect a substantial abundance of birds. Estimates of 

continued population viability, including predicted annual rates of recruitment or 

survival, would change. Additionally, one or both of the two following conditions 

must be met: (1) At least one large population of birds would have a reduction in 

the estimates of continued population viability, including predicted annual rates of 

mortality, recruitment or survival, some or all of which would seriously decline 

(causing sublethal impacts to be irreversible); and/or (2) one or more incidents 

would occur where at least one large population would experience chronic 

behavior changes or mortality that would affect a large population and with 

measurable impact on a population.

4.8.1 Description of the Affected Environment

This description of birds focuses on the factors that control the relative vulnerability of 

different bird groups to impacts. Passerines, or songbirds, represent many of the breeding and 

wintering birds within the Gulf Coast States. They are only found offshore when migrating across the 

Gulf of Mexico, and they cannot stop and rest or feed on the water. Some species of birds (some 

seabirds) live primarily offshore except when breeding and, therefore, are rarely observed in the 

nearshore environment. More information about seabirds is provided in the Five-Year Program EIS 

(USDOI, BOEM, 2016b). The remaining species are found within coastal and inshore habitats and 

may be more susceptible to potential deleterious effects resulting from OCS oil- and gas-related 

activities because many of these species largely overlap spatially and temporally with OCS oil- and 
4-236 Gulf of Mexico Multisale EIS

gas-related activities, because of their abundance or density, and because of the potential of spilled 

oil impacting their habitat or food resources. A detailed analysis of the impacts to birds is presented 

in the chapters below.

Feeding Habits

A bird’s feeding method is one of the important determinants of a bird’s habitat choice. Bird 

species feed either in the water (aquatic feeders) or terrestrially. Aquatic bird species that feed by 

wading include some shorebirds and other waders such as herons. Some species have 

comparatively short legs and wade in relatively shallow water or walk on beaches to feed; other 

species feed in somewhat deeper as well as shallow water and have longer legs. Shorebirds are 

adapted to take advantage of tidally-influenced habitat. Their diurnal movements and habitat use 

appears to be closely linked to tidal advances and recessions, i.e., lunar, solar, or wind-driven tides. 

Shorebirds and other wading species feed on invertebrates and fish. Aquatic bird species, including 

some ducks, may feed by dabbling at the water surface. Many aquatic bird species, including some 

ducks and many seabirds, feed by diving into the water from the air or water surface for either plant 

or animal food. Some seabirds aggregate at patches of floating macroalgae Sargassum to feed or 

rest, at least in tropical waters (Haney, 1986). A list of examples of marine and coastal birds can be 

found in the Five-Year Program EIS (USDOI, BOEM, 2016b).

Oil from reasonably foreseeable spills is not expected to be very commonly encountered by 

birds. Still, birds are a relatively vulnerable resource because feeding habits may result in 

encounters between birds and OCS oil- and gas-related activity. For example, waders feed in 

shallow water, which is important because oil from previous spills that happened to reach the 

sediment may accumulate in the sediment, where birds may encounter it. Diving birds can 

encounter an oil slick either if they begin their dive in the air and pass across the water surface or if 

they begin their dive floating on the water surface. Birds may feed and roost in the water or at or 

near the water’s edge, where they may be impacted by an oil spill. Marsh birds feed in or at the 

water’s edge of marshes, where oil may accumulate in the sediment. Also, platforms may represent 

profitable foraging areas for seabirds, raptors, and potentially passerines (Wiese et al., 2001; 

Russell, 2005). More information about raptors and passerines is provided in the Five-Year Program 

EIS (USDOI, BOEM, 2016b). 

Habitat

The open Gulf (including blue water [off the continental shelf], shelf, and inshore open water) 

is used by terrestrial birds (including passerines), shorebirds, long-legged wading birds, and raptors 

for trans-Gulf migration (Russell, 2005). More information on shorebirds is provided in the Five-Year 

Program EIS (USDOI, BOEM, 2016b). The open GOM is used by seabirds for feeding and roosting, 

and some seabirds never come ashore in the Gulf of Mexico. Wetlands (consisting of trees, shrubs, 

marshes, and/or unvegetated flats) (refer to Chapter 4.3, Coastal Habitats) are used by waterfowl, 

shorebirds, long-legged wading birds, secretive marsh birds (e.g., rails), raptors, and terrestrial birds 

(including passerines) for feeding, roosting, and/or nesting (Portnoy, 1978 and 1981; Hunter et al., 

2006; Brown et al., 2001; and North American Waterfowl Management Plan, 2004). More 
Description of the Affected Environment and Impact Analysis 4-237

information on waterfowl is provided in the Five-Year Program EIS (USDOI, BOEM, 2016b). 

Beaches and dunes are used by seabirds and shorebirds for feeding, roosting, and/or nesting 

(Portnoy, 1978 and 1981; Hunter et al., 2006). Coastal forests are used by trans-Gulf migrant 

terrestrial birds for feeding, roosting, and/or nesting. Several species breed along the coastline of 

the Gulf of Mexico (where spilled oil may travel and persist) and, therefore, may be especially 

vulnerable to the impacts of an oil spill. Previous surveys indicate that Louisiana, Texas, and Florida 

are among the primary states in the southern and southeastern U.S. for both nesting colonies and 

the total number of breeding coastal and marine birds (Portnoy, 1978 and 1981; Hunter et al., 2006). 

All avian species show varying levels of fidelity to both breeding and wintering areas. The global 

Important Bird Areas Program was developed by the National Audubon Society to identify and 

conserve areas that are vital to birds and other biota. More information on the program is provided 

in the Five-Year Program EIS (USDOI, BOEM, 2016b).

Population Ecology

The level of any impact to different species of birds depends on its population ecology, 

including the age or life stages and sex that are impacted. For example, relevant population ecology 

factors for seabirds includes delayed maturity, low reproductive potential, periodic nonbreeding, low 

first-year survival, and small clutch size. These factors can make them the most vulnerable to 

impacts. Relevant population ecology is not always available to explain oiling mortality from an oil 

spill because the sex and life stage of recovered oiled birds is not always known or recorded. For 

example, for the Deepwater Horizon explosion, oil spill, and response, only the species information 

was available, not the age, life stage, or sex of oiled birds. The location, magnitude, and other 

conditions of an impact-producing factor that may seem to have relatively low contact with and 

relatively reduced mortality for one species may in fact cause other bird species increased mortality 

and long-term impacts. Populations appear to be most sensitive to changes (even small decreases) 

in adult survival, particularly female survival because adult female survival appears to be the driver 

for these populations (Russell, 1999).

Migration

Some birds that utilize the GOM are year-round resident species. These species may be 

exposed to impacts during any time of the year. However, most of the bird species that utilize the 

GOM are migratory. They may breed or overwinter in the GOM, or stop over on the northern Gulf 

Coast while migrating. For example, some birds may breed on the coast and depart during the 

winter months. However, some birds breed in the northern United States or the Caribbean and 

overwinter offshore the GOM and never come ashore. As an example, the brown booby breeds in 

the Caribbean, Mexico, and Central America, while the white-tailed tropicbird breeds in the 

Caribbean. Some birds of both species overwinter in the pelagic GOM, but little is known about 

where they are located then in the GOM (Schreiber and Norton, 2002; Lee and Walsh-McGehee, 

1998). All avian species show varying levels of fidelity to both breeding and wintering areas. Birds 

may be present in the Gulf of Mexico only during one or two of the following seasons: breeding 

and/or overwintering and/or migrating. Therefore, seasonal timing of an impact helps determine 

which species would be affected.
4-238 Gulf of Mexico Multisale EIS

Each spring, vast numbers of birds migrate northward across the GOM enroute to breeding 

habitats in the United States and Canada from their wintering quarters in the neotropics. They 

depart in large numbers from the Yucatan Peninsula and the Isthmus of Tehuantepec (Russell, 

2005). The path they take depends on supporting tail wind direction, which depends, in turn, on the 

presence of an East Continental High Pressure synoptic weather pattern over the continental United 

States or a Bermuda High Pressure synoptic weather pattern over the Atlantic Ocean around 

Bermuda (Russell, 2005). The East Continental Highs move east and become Bermuda Highs. 

During an East Continental High in spring, the birds may migrate especially from the east-southeast 

to the northwest Gulf of Mexico (Figure 4-20). During a Bermuda High in spring, the birds may 

migrate especially from the south-southeast to the northcentral Gulf of Mexico (Figure 4-21). They 

are mostly seed eaters and insectivores and, therefore, may stop over and feed on available insects 

but mostly not on aquatic organisms. An example of a spring migration corridor is for wood thrush, 

which migrates most densely from the Yucatan Peninsula across the central Gulf of Mexico (Figure

4-22). Synoptic weather patterns were not specified for this migration corridor. Following a short 

breeding season in the north, most of these birds return southward across the GOM; their numbers 

are then augmented by offspring produced over the summer (Russell, 2005). During an East 

Continental High in fall, an example of a fall migration route that could initiate in the north central 

Gulf of Mexico and terminate on the eastern Bay of Campeche, the Yucatan Peninsula, western 

Cuba, and northern Honduras is shown in Figure 4-20. In fall, few birds migrate during a Bermuda 

High. An example of a fall migration corridor is for wood thrush, which migrates most densely from 

Florida across the eastern Gulf of Mexico (Figure 4-23). Synoptic weather patterns were not 

specified for this migration corridor. Migrating songbirds may stop over on offshore platforms. 

Platform density with respect to migratory routes is shown in Figure 4-24, and its high spatial 

variability at a large scale suggests that the probability of a bird encountering one or more platforms 

is also highly variable for routes at a large scale. Migratory birds may also stop over on boats, other 

vessels, and coastal terrestrial habitat when crossing the GOM in the spring or fall. Three of the four 

migratory flyways in the United States depend on the GOM as part of their route. Executive Order 

13186 protects migratory birds and emphasizes species of conservation concern. It requires 

analyses of birds in NEPA documents and a Memorandum of Understanding between the action 

agency (BOEM and BSEE) and FWS. Also, all migratory birds are protected under the Migratory 

Bird Treaty Act. The Act provides limits on when migratory birds can be taken, killed, possessed, 

transported, or imported.

For some bird species, both spring and fall migrations take place in a series of stops among 

various staging areas. At these staging areas, birds spend time primarily feeding to recover 

reserves necessary for the sustained flight to the next staging area (Norris, 2005; Krapu et al., 2006; 

Skagen, 2006). Many coastal habitats along the GOM are critical for such purposes.

More information on bird migration is provided in the Five-Year Program EIS (USDOI, 

BOEM, 2016b).
Description of the Affected Environment and Impact Analysis 4-239

Figure 4-20. Migration Routes for Trans-Gulf Migratory Birds in the Presence of an Eastern 

Continental High. (The Eastern Continental High is indicated by the letter "H," and the 

corresponding clockwise somewhat concentric synoptic wind patterns are indicated by 

lines and arrows.)
4-240 Gulf of Mexico Multisale EIS

Figure 4-21. Migration Routes for Trans-Gulf Migratory Birds in the Presence of a Bermuda High. (The 

Bermuda High is indicated by the letter "H," and clockwise somewhat concentric synoptic 

wind patterns are indicated by lines and arrows.)
Description of the Affected Environment and Impact Analysis 4-241

Figure 4-22. Spring Wood Thrush Partial Migratory Corridor in North America (reprinted with 

permission from Brenner et al., 2016; movement data for this map was provided to The 

Nature Conservancy by Bridget Stutchbury and collaborators). 
4-242 Gulf of Mexico Multisale EIS

Figure 4-23. Fall Wood Thrush Partial Migratory Corridor in North America (Reprinted with 

permission from Brenner et al., 2016; movement data for this map was provided to The 

Nature Conservancy by Bridget Stutchbury and collaborators). 
Description of the Affected Environment and Impact Analysis 4-243

Figure 4-24. Platform Density and Spring Migration Routes for Trans-Gulf Migratory Birds.

Baseline Populations

Baseline populations of birds have been affected by recent events, including hurricanes and 

the Deepwater Horizon explosion, oil spill, and response. However, no species or subspecies of 

birds that has been listed as federally endangered or threatened, of conservation concern to the U.S. 

Fish and Wildlife Service, State listed, or of State conservation concern has been reported in sharp

decline or otherwise harmed by either recent hurricanes or the Deepwater Horizon explosion, oil 

spill, and response. Definitions for the impact levels used above in this analysis (Table 4-16) use 

concepts of flock or colony size affected. For two examples of flock size, royal terns have compact 

flocks up to several thousands (Buckley and Buckley, 2002), while dunlin (a shorebird) has flocks of 

10-100 (Buchanan et al., 1988). For examples of colony size, in Louisiana, which takes up much of 

the CPA, in 2001, brown pelican colonies consisted of about 8,484 breeding pairs and royal terns 

consisted of about 12,500 breeding pairs (Michot et al., 2003). Only about two seabird colonies in 

Lousiana in 2001 had >10,000 breeding pairs. In 2001, the total numbers of seabird colonies in 

Louisana were 158, composing 101,957 breeding pairs (Michot et al., 2003). No hurricanes have 

made baseline changes since the 2012-2017 WPA/CPA Multisale EIS, which was published in 2012 
4-244 Gulf of Mexico Multisale EIS

(USDOI, BOEM, 2012b). There is new information on baseline changes resulting from the 

Deepwater Horizon explosion, oil spill, and response, as described below.

Hurricane-related flooding can drown nests, and associated winds can kill birds due to 

impact with objects like trees. In addition, hurricane impacts to coastal ecosystems can have 

deleterious effects to foraging and nesting birds that utilize those habitats. However, no surveys of 

mortality from such impacts related to Hurricane Katrina and other storms were located.

The following information is relevant to evaluating reasonably foreseeable significant adverse 

impacts on the human environment but not essential to a reasoned choice among alternatives. 

Mortality from the Deepwater Horizon explosion, oil spill, and response was sufficient to cause a 

small negative shift in baseline abundances for seabirds. Total seabird mortality seaward of 25 mi 

(40 km) from shore due to the Deepwater Horizon explosion, oil spill, and response was estimated at 

200,000 birds (Haney et al., 2014a). Estimates of breeding population sizes were 

60,000-15,000,000 for four procellariiform (shearwaters and related) species, 9,000 for one 

pelecaniform (pelican and related) species, and 96,000-500,000 for three charadriiform (gulls and 

related) species (Haney et al., 2014a). Total bird mortality landward of 25 mi (40 km) from shore 

was estimated as 600,000 birds using one model and 800,000 birds using another (Haney et al., 

2014b). In perspective, in three analyzed species of seabirds, estimated losses due to the 

Deepwater Horizon explosion, oil spill, and response were 12 percent or more of the total population 

estimated present in the northern GOM (Haney et al., 2014b). Because the effect was on the total 

populations, the impact was major. This new information estimates a small negative shift in baseline 

numbers. Incremental impacts caused by the negative shift in baseline numbers were not sufficient 

to change the conclusions for the impact analysis of a proposed action. The shift was extrapolated 

from the increased mortality due to the Deepwater Horizon explosion, oil spill, and response. 

However, these changes to the baseline did not identify any species whose population was likely to 

be impacted by a proposed action or alternatives.

The following information is relevant to evaluating reasonably foreseeable significant adverse 

impacts on the human environment but not essential to a reasoned choice among alternatives. 

Recovery (NRDA) data have become available since the analyses by Haney et al. (2014a and 

2014b). Total nearshore mortality was determined in six recent NRDA final reports on the 

Deepwater Horizon explosion, oil spill, and response as 54,099-100,134 waterbirds (USDOI, FWS, 

2015a, 2015b, 2015c, 2015d, and 2015e; Industrial Economics, Inc., 2015a Total offshore mortality 

was determined in one NRDA final report on the Deepwater Horizon explosion, oil spill, and 

response as 2,317-3,141 birds (Industrial Economics, Inc., 2015b). These NRDA reports did not 

include estimates of lost bird-years used in NRDA’s reports of some previous spills, as discussed in 

Zafonte and Hampton (2005). New information is also provided by two articles (not funded by 

NRDA) on the Deepwater Horizon explosion, oil spill, and response. Franci et al. (2014) found no 

confirmed impacts of oil on the endocrine status and no evidence of exposure to oil of northern 

gannets that migrated to eastern Canada after overwintering in the northern Gulf of Mexico in the 

winter of 2010-2011. Seegar et al. (2015) found evidence in the fall of 2010 of polycyclic aromatic 

hydrocarbon (PAH) contamination of blood of migrant tundra Peregrine Falcons that probably were
Description of the Affected Environment and Impact Analysis 4-245

exposed to Deepwater Horizon PAHs in oil. However, blood of migrant tundra peregrine falcons 

found in the spring of 2011 had a small amount of PAHs that were not from the Deepwater Horizon

oil. Finally, blood in migrants in the fall of 2011 could have had moderate levels of PAHs from a 

petroleum source, but it was probably not Deepwater Horizon oil (Seegar et al., 2015).

Mortality can indicate substantial impacts from an oil spill even when sharp declines or other 

impacts on population size have not been measured. No reports of the impact levels of hurricane on 

the rates of population decline or any other impacts on population size were located.

4.8.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from the 

routine activities, accidental events, and cumulative impacts described in Chapter 3 and their 

potential effects on birds that would potentially be impacted by a proposed action or the alternatives. 

This analysis would apply to all alternatives considered; however, the level of impacts would be 

different for each alternative, as discussed below in Chapters 4.8.2.5-9. 

4.8.2.1 Routine Activities

Impacts from routine activities to coastal, marine, and migratory birds include impacts from 

routine discharges and wastes, noise, platform severance with explosives (barotrauma), geophysical 

surveys with airguns, platform presence and lighting, construction of OCS-related onshore facilities, 

and pipeline landfalls. For marine and coastal birds, more information on impact-producing factors 

of routine activities can be found in the Five-Year Program EIS (USDOI, BOEM, 2016b). In that 

document, noise from seismic sources, vessels, aircraft, drilling, trenching, production, and platform 

removal is discussed.

Discharges and Wastes. These include produced waters, drilling muds and cuttings, and 

routine air emissions. Routine discharges and wastes affecting air and water quality (Chapter 4.1, 

Air Quality, and Chapter 4.2, Water Quality) are under the jurisdiction of USEPA (including NPDES) 

or BOEM, and regulations assure that impacts on birds are negligible because USEPA’s and 

BOEM’s regulations protect against the unreasonable degradation of the marine environment.

Helicopters and Vessels. The OCS oil- and gas-related helicopters and vessels have the 

potential to cause noise and disturbance. However, flight altitude restrictions over sensitive habitat, 

including that of birds, may make serious disturbance unlikely. Birds are also known to habituate to 

noises, including airport noise. It is an assumption that the OCS oil- and gas-related vessel traffic 

would follow regular routes; if so, seabirds would find the noise to be familiar. Therefore, the impact 

of OCS oil- and gas-related noise from helicopters and vessels to birds would be expected to be 

negligible. 

Platform Severance and Rigs-to-Reefs. These activities are discussed in Structure-Removal 

Operations on the Gulf of Mexico Outer Continental Shelf: Programmatic Environmental 

Assessment (USDOI, MMS, 2005). Refer to Chapter 3.1.6 for more information on platform 
4-246 Gulf of Mexico Multisale EIS

removal. Platform severance with explosives may potentially kill one or more birds from barotrauma 

if a bird (or several birds because birds may occur in a flock) is present at the location of the 

severance. For the impact of underwater sound, a threshold of 202 dB sound exposure level (SEL) 

for injury and 208 dB SEL for barotrauma was recommended for the Brahyramphus marmoratus, a 

diving seabird (USDOI, FWS, 2011). Platform relocation in the Rigs-to-Reefs program would 

potentially provide foraging habitat for birds, which would be a positive impact. The overall impact of 

severance and rigs-to-reefs would be minor because positive impacts do not completely counteract 

barotrauma, for which possible lethality would offset expected low frequency.

Geological and Geophysical (G&G) Surveys. These are discussed in the Atlantic OCS 

Proposed Geological and Geophysical Activities: Mid-Atlantic and South Atlantic Planning Areas; 

Final Programmatic Environmental Impact Statement (USDOI, BOEM, 2014a) and Five-Year 

Program EIS (USDOI, BOEM, 2016b). Refer to Chapter 3.1.2.1 for more information on G&G 

information in the GOM. Geological and geophysical surveys with airguns may kill one bird (or a 

small number of individuals occurring in a flock) from barotrauma in one or more incident. This 

impact would be minor. 

Platform Lighting and Nocturnal Circulation. Potential impacts of platform lighting can be 

dependent on spectra, intensity, and weather conditions (refer to Chapter 3.1.3.4.3 of this Multisale 

EIS and to the Five-Year Program EIS [USDOI, BOEM, 2016b] for more information on platform 

lighting). Obstruction lighting is considered under cumulative impacts because it is under the 

jurisdiction of the USCG and not likely subject to change. Obstruction lighting on proposed platforms 

could attract trans-Gulf migrant birds during low-visibility conditions because it is white, and so it 

includes spectral red. Birds may have the following behaviors in any combination, any order, any 

frequency, and any duration at platforms: resting; feeding; collision with platforms; and nocturnal 

circulation (Russell, 2005). In nocturnal circulation, birds fly around the lit platforms. Nocturnal 

circulation may be brief with little impact or may be long term and burn up energy reserves (Russell, 

2005). The number of times a bird stops at platforms is unknown. Birds would likely stop over on 

platforms with lights with spectral red or with high intensity during overcast, rainy, or foggy conditions 

at night (Marquenie et al., 2013). The potential range of a songbird adapted to fatten up enough to 

cross the GOM is approximated by data on shorebirds. The computed maximum non-stop range of 

a bar-tailed godwit (a shorebird) leaving Alaska (based on a model of fuel load) was to the South 

Pole (Pennycuick and Battley, 2003). It is about 739 mi (1,189 km) from Galveston, Texas, to the 

Yucatan Peninsula, Mexico; it is about 10,156 mi (16,344 km) from Alaska to the South Pole. 

Populations of birds may be affected if many of them do not make it across the GOM because of 

stopping at platforms, which may affect species richness. That may, in turn, affect bird watching and 

bird hunting. Full or almost full population recovery means that impacts to trans-Gulf migrants would 

be minor. 

Platform Lighting and Collisions. Minor impacts would result partly because total estimated 

annual mortality from collisions due to structure presence has been estimated at 

200,000-321,000 birds of the up to 316 million birds that migrate (Russell, 2005). Those numbers 

are of the same order of magnitude as overall mortality from the Deepwater Horizon explosion, oil 
Description of the Affected Environment and Impact Analysis 4-247

spill, and response. Nonlethal (e.g., reproductive) impacts of collisions are not expected but they are 

expected for nocturnal circulation. Impacts on trans-Gulf migrants from platform presence and 

particularly light spectra (Marquenie et al., 2013) need further study. More information on the impact 

of platform presence is provided in the Five-Year Program EIS (USDOI, BOEM, 2016b).

Platform Presence, Produced Waters, and Seabirds. Seabirds are attracted to structures 

and may benefit from underwater reef organisms associated with the structure. Neither toxicological 

effects of produced waters on seabirds nor the possible attraction of seabirds to the plumes of 

discharged produced water have been studied at all. However, USEPA mandates testing the toxicity 

of produced waters to other organisms, which may sufficiently protect birds, resulting in negligible

impacts. There is a short delay between taking produced-water samples and getting them tested in 

laboratories, during which seabirds could be exposed. The study of toxicology in birds has been 

proposed.

Construction of Onshore Facilities. The OCS oil- and gas-related construction of onshore 

facilities would require obtaining permits for any projects that could harm wetlands or any other 

habitats protected by conservation laws and regulations. For example, construction in a wetland 

area would require a COE permit under Section 404 of the Clean Water Act; this would include 

mitigations and monitoring of the activities. Further reinforcement of wetland protection is expected 

because of the long-standing goal of no net wetland loss. As a result, negligible impacts are 

expected from OCS oil- and gas-related construction of onshore facilities and consequent habitat 

loss.

Pipeline Landfall: Impacts from a pipeline landfall could disturb shoreline or wetland habitat 

that is utilized by birds. Up to one pipeline landfall is projected. The resulting habitat loss to birds 

from the installation method of directional drilling is expected to result in a negligible impact.

4.8.2.2 Accidental Events

Impacts for accidental events to birds are caused by oil spills, spill cleanup, and emergency 

air emissions. Impacts of hydrocarbons from oil spills depend on the hydrocarbons’ ultimate 

destination, i.e., in the air (from evaporation), in the water, or in the sediment. Birds may be affected 

by hydrocarbons through means of inhalation or ingestion when eating oiled benthic, planktonic, or 

pelagic prey; preening oiled plumage; or drinking hydrocarbons in water (Leighton, 1993). Birds 

(Leighton, 1993) and prey may be killed by toxic oiling. Oiled plumage can also be lethal because it 

causes loss of insulation, ability to fly, and buoyancy; also, oil can be transferred from such plumage 

to egg shells during incubation and can cause embryo mortality (Leighton, 1993). While some birds 

can be rehabilitated after contamination by oil or dispersants, others may sustain injuries or die. Oil 

and dispersants can affect birds at the small population level. Birds that feed aquatically are 

vulnerable to oil, and migrants or residents that occur in the GOM when oil from a spill is present are 

also vulnerable. These circumstances are discussed in detail in Chapter 4.8.1. Impacts on longlived seabirds may last longer because generation time is longer, and they may also be delayed. 

For an example of the latter, a delay on first-breeders would have a delayed reduction in recruitment, 
4-248 Gulf of Mexico Multisale EIS

which would go unnoticed until years after exposure. Therefore, detection would not occur without 

long-term studies. In addition, oiling may sometimes be more severe in shallow water, wetlands, 

both bayside and gulfside intertidal shorelines (including beaches), and dunes where avian diversity 

and abundance, as well as hydrocarbon accumulation and persistence, may be high. Barrier islands 

may be composed of all of these component habitats, and the islands give important support to 

breeding and wintering waterbirds (Curtiss and Pierce, 2016; Selman et al., 2016). The islands are 

also important migratory stopovers. Refer to Chapter 4.3 (Coastal Habitats) for a discussion of the 

fate of oil in wetlands. Sometimes, because of lack of adequate personnel training or the sheer 

scale of activity, shoreline cleanup (Chapter 3.2.8) may disturb nesting birds and have a minor

impact. Disturbance to GOM nonnesting shorebirds from the Deepwater Horizon oil-spill cleanup 

may have affected bird conditions later on the northern breeding grounds (Henkel et al., 2014). An 

oil-spill sublethally affecting birds that migrate may have carry-over impacts to one or migratory 

destinations, including the ecosystems at those destinations.

Combined probabilities of occurrence and contact of an oil spill with shoreline bird species 

and nearshore bird species can be found in Figures E-2 through E-7 and Figure E-20, 

respectively. Seabirds may take longer to recover from the impacts of an oil spill than other bird 

groups because of their unique population ecology (demography), regardless of the intensity of the 

initial impacts on a population. Long-term impacts are possible to seabirds (with long generation 

time) that delay first breeding (and hence impacts on first breeders would have a delayed reduction 

in recruitment) (Dunnet et al., 1982). Long-term impacts also occur when local colony or flock 

extirpation occurs, resulting in loss of species richness (community structure) until a colony or flock 

can recover from extirpation. Refer to Chapter 4.12 (Recreational Resources) for a discussion of 

the socioeconomics of wildlife tourism. Finally, long-term impacts occur when oil persists 

(sometimes for years) in sediment and may contact seafloor organisms or be resuspended and 

contact organisms in the water column. Resuspended oil may then be transported to other areas 

and settle out where it could be encountered by birds. The impact level from oil spills would depend 

on the combined result of the effects on habitat (sediment oiling in shallow water) and abundance 

(effect on small or large populations) of affected birds, as well as long-term persistence of oil in 

some habitats. A minor offshore spill (<1,000 bbl) could disappear even before a crew could arrive 

and clean it up; however, because the spill would be so small, impacts would be negligible. A 

minor inshore spill (e.g., <1,000 bbl spilled during vessel refueling) could be completely cleaned up

right away; therefore, impacts would be negligible. Impacts of a large spill (≥1,000 bbl) associated 

with a proposed action under Alternative A, B, C, or D would be expected to be moderate because a 

large population of birds could be chronically disturbed or affected, because of the size and 

persistence of the oil spill.

Emergency air emissions may cause various toxic effects to a bird or flock of birds exposed 

to the discharge. An example would be a hydrogen sulfide leak from a pipe. A single incident of 

toxic effects could affect nothing more than a flock. On the basis of the frequency of such events, 

impacts from emergency air emissions would be minor. 
Description of the Affected Environment and Impact Analysis 4-249

4.8.2.3 Cumulative Impacts

OCS Oil- and Gas-Related Impacts

Baseline populations are discussed in Chapter 4.8.1 (Description of the Affected 

Environment). Routine OCS oil- and gas-related impacts that could add to the cumulative impacts to 

coastal and marine birds are effects to air and water quality, noise, platform severance with 

explosives (barotrauma), geophysical surveys with airguns (barotrauma), platform presence and 

lighting, and construction. They are discussed in detail in the “Routine Activities” section above. 

Accidental events are oil spills, cleanup, and emergency air emissions, which are discussed in the 

“Accidental Events” section above. Cumulative OCS oil- and gas-related impacts are presented 

briefly here.

Impacts from routine air and water discharges are discussed in Chapters 4.1 (Air Quality) 

and 4.2 (Water Quality). As a result of these discharges, impacts on birds would be expected to be 

negligible. Drilling discharges, produced waters, and the discarding of marine trash and debris 

would have negligible impacts on birds. Impacts of aircraft and vessel noise would be expected to 

be negligible. Impacts of severance with explosives during platform decommissioning and of 

geophysical surveys with airguns would have minor impacts. Structure presence would possibly 

result in collision of birds with a structure, nocturnal circulation, or an opportunity to rest and/or feed. 

It may have a net beneficial or a net negative impact on birds (Ramirez et al., 2014; Marquenie et al., 

2013). Structure presence is discussed in the “Incomplete or Unavailable Information” section 

below. Impacts of coastal OCS oil- and gas-related facility construction would be expected to be 

negligible. More information on all of the routine impacts discussed above (including all types of 

noise and routine discharges, except for produced waters) is provided in the Five-Year Program EIS 

(USDOI, BOEM 2016c).

A large oil spill (≥1,000 bbl) could moderately impact coastal and marine birds, and oil-spill 

response and emergency air emissions could have minor impacts on them; refer to the “Accidental 

Events” section above for more details. Modeling shows that, without a thorough understanding of a 

species’ habitat use and preferences, a species’ ability to locate and colonize alternative habitat, and 

the population structure, it is difficult to make inferences regarding the ability of individual birds or 

groups to successfully emigrate and colonize novel, undisturbed habitat (assuming it is available) 

(Fahrig, 1997, 1998, and 2001). BOEM used scientific reasoning about habitat in lieu of empirical 

studies to help understand the impacts of oil spills on colonial nesting birds. Habitat may be 

occupied at or below carrying capacity, or it may not be occupied at all, so it may have various 

amounts of room for immigrant birds (and various sources of mortality or depression of realized 

reproductive rate) when immigrants are escaping disturbance or an oil spill. For habitat that is 

occupied, any single patch or group of patches of habitat may change periodically in the resource or 

resources (which could include the amount of the habitat itself) that are limiting to its occupants. The 

impact of an area of major degradation of habitat quality (with no change in total habitat area) can be 

more or less important than the impact of complete loss of a large area of habitat. For purposes of 

this discussion, habitat availability is defined as presence of unoccupied habitat. The following 

statement applies only if birds are able to move into habitat that is occupied below carrying capacity. 
4-250 Gulf of Mexico Multisale EIS

Habitat does not become limiting until it is filled up (completely occupied), so habitat availability is 

not itself limiting. Filled habitat (habitat limitation) can be ideal for birds if that is the pervasive 

condition of a bird population. Filled habitat only becomes a problem when no extra space is 

available for immigrants trying to escape a major event such as an oil spill or when the amount of 

filled habitat is so small that a bird is listed as threatened, endangered, or of conservation concern. 

Unoccupied habitat for colonial nesting birds is likely pervasive because periodic surveys of bird 

colonies in the northern Gulf of Mexico show regular formation of completely new bird colonies. 

Therefore, impacts of an oil spill on colonial nesting birds are expected to be negligible. Impacts 

from pipeline landfalls are expected to be negligible. 

Non-OCS Oil- and Gas-Related Impacts

All OCS oil- and gas-related impact-producing factors and their impact levels also hold for 

State oil- and gas-related activities. The moderate impacts from State oil and gas activities include 

a large oil spill (≥1,000 bbl). Impact levels for collision of trans-Gulf migrants with platforms, and 

possibly nocturnal circulation of trans-Gulf migrants, need further study. Impacts are expected to be 

minor. A large tanker spill (≥1,000 bbl) would have the same impact (moderate) as a similar sized 

OCS oil- and gas-related spill or State oil- and gas-related spill discussed above. Impacts to birds 

would be expected to be moderate. 

A source of cumulative impacts is obstruction lighting on platforms in State waters or on the 

OCS; obstruction lighting is under the jurisdiction of the USCG and is not likely to be changed by 

mitigations to protect birds. The impact level of obstruction lighting would need further study.

In addition to the OCS oil- and gas-related discharges discussed above, other regulated 

discharges include the discharge of bilge or ballast water from ships, runoff to waters, and industrial 

discharges into the coastal atmosphere, all of which are regulated by the USEPA. Also, agricultural 

nutrient (fertilizer) and pesticide runoff occurs. For more information and impact levels for runoff, 

other discharges into waters, and discharges into the atmosphere, refer to Chapter 4.1 (Air Quality) 

and Chapter 4.2 (Water Quality). Pollutants are expected to be diluted to a level below that which is 

harmful to birds or otherwise safely disposed of, and effects are not expected at a population level.

Discard of trash and debris from non-OCS oil- and gas-related sources (e.g., from State 

oil- and gas-related activities, recreational fishing boats, and land-based sources; refer to Chapter 

3.3.2.3.7) is prohibited; however, despite regulation, unknown quantities of plastics and other 

materials are discarded and lost in the marine environment and remain a threat to individual birds. 

Many species readily consume plastic debris, either intentionally or incidental to consuming prey, 

and can become trapped or entangled in discarded fishing line or nets. Although the short-term 

prognosis suggests that plastic impacts are increasing significantly, analyses also suggest that 

reductions in exposure would result in reduced ingestion (Wilcox et al., 2015). Seabirds are 

sometimes caught in commercial fishermen’s gear. Seabird bycatch numbers in the GOM (Hale 

et al., 2009) indicated that the pelagic and bottom longline fisheries had negligible impacts on 

seabirds. Discarded bycatch of fishes and invertebrates would benefit seabirds. Impacts to birds 
Description of the Affected Environment and Impact Analysis 4-251

from trash and debris as a whole are expected to be moderate in the short term but negligible with 

forecasted reductions in exposure (Wilcox et al., 2015).

The Mississippi River watershed contributes nutrients causing a seasonal population 

explosion of phytoplankton, which decomposes to create a hypoxic or anoxic “dead zone” over the 

continental shelf (Chapter 3.3.2.12). Aquatic food for coastal waterbirds could be decimated in 

places in the hypoxic zone. No massive phytoplankton blooms have been reported to produce 

massive mortality to seabirds and other waterbirds in the zone. It is possible that birds are able to 

move from impacted areas with no food to patches of sufficient food; doing so would make the 

effects short term. Impacts on a whole population are expected to be minor. 

Historical wetland loss due to Mississippi River hydromodification (Chapter 3.3.2.10) would 

be at least somewhat ameliorated by wetland creation from Atchafalaya River sediments and coastal 

restoration and hurricane protection programs. Also Louisiana’s Master Plan, which was partly 

designed for maximizing coastal wetlands, would likely increase habitat for four selected waterbird 

species and for neotropical birds over the next 50 years (refer to Chapter 4.3, Coastal Habitats). 

These predictions are based on Habitat Suitability Index models and were controlled for other, 

non-habitat environmental variables (Nyman et al., 2013). Therefore, wetland loss would probably 

not be an issue that would exacerbate other impacts of a proposed action and other cumulative 

impacts for coastal and marine birds. For these reasons, impacts on whole populations are 

expected to be negligible. 

In addition to impacts to habitat from Mississippi River hydromodification, impacts to habitat 

could also be due to urbanization, or they could be rural. Habitat (e.g., wetland) loss, alteration, and 

fragmentation associated with building, factory, and road construction is kept from harming sensitive 

bird habitat by standard mitigating measures required by COE and State wetland permitting 

regulations. A major policy goal (not yet fully reached) is “no net loss” of wetlands. However, Ward 

et al. (2010) indicates that urbanization may alter wetland hydrology rather than destroy wetlands 

and that may cause a reduction in abundance of wetland birds. Such impacts would probably be 

avoided by protection or active management of wetland hydrology regimes (Ward et al., 2010). 

When such procedures and a no-net-loss policy are in place, impacts to birds would be expected to 

be negligible. 

Military activities, including training overflights and sonic booms, would occur in special areas 

offshore in seabird habitat. Military operations in the Gulf of Mexico are undertaken primarily by the 

U.S. Air Force and the U.S. Navy within federally designated areas for the purposes of training 

personnel, as well as research, design, testing, and evaluation activities. There are 18 U.S. military 

bases along the northern Gulf of Mexico. The greatest impacts would come from sonic booms, 

which would likely cause a short-term behavioral change such as flushing of a flock resting on the 

water or cessation of feeding by a flock. No individual or group of individuals would be injured or 

killed. Impacts would be expected to be negligible. 
4-252 Gulf of Mexico Multisale EIS

Nonconsumptive recreation includes recreational boating; it also involves beach use during 

bird-watching activities, riding in all-terrain vehicles, and walking and jogging with pets. All forms of 

beach use may cause birds to become stressed and fly away, possibly with no possible destinations 

with habitat of equal value for feeding, nesting, roosting, or sleeping. Stress and ejection from 

habitat on a large scale may cause sublethal depression of reproductive productivity, which in turn 

may result in population decline that may exceed decline resulting from mortality. For economic 

impacts, refer to Chapter 4.12 (Recreational Resources). In most cases, recreational boats are 

subject to strict speed and wake restrictions. Disturbances of an area could be regular but impacts 

would be benign and direct (limited to the time period of disturbance); therefore, they would be 

minor. 

Consumptive recreation (hunting game birds) is regulated. Each state and Canadian 

province in each flyway, along with FWS, are the source for waterfowl hunting regulations. Usually, 

total mortality of hunted species does not increase because of hunting—it remains the same 

because the overall carrying capacity of a species does not change with hunting. However, some 

species of game birds have experienced hunting-related mortality impacts at the population level, a 

major impact that would be mitigated to a net negligible impact by adjustments in hunting 

regulations.

Use of navigable waters by vessels may cause erosion of banks by vessel wakes, causing 

wetland habitat loss. The impacts to wetlands from non-OCS oil- and gas-related vessel traffic is 

expected to be moderate to major (Chapter 4.3.1.2.3, Estuarine Habitats, Cumulative Impacts). 

Because wetland habitat loss would be moderate to major, the potential impacts on birds would be 

moderate to major also.

There are a myriad of anthropogenic avian mortality sources, including collisions and 

predation by domestic cats. No GOM regional estimates are available for annual mortality rates for 

collisions with vehicles, collisions with buildings, or predation by domestic cats. However, recent 

quantitative national estimates allow for a qualitative extrapolation to the GOM. An estimated range 

of national annual mortality from collision with vehicles is 62-275 million birds per year (Loss et al., 

2014a). An estimate of national annual mortality from collision with buildings is 599 million birds per 

year (Loss et al., 2014b). Finally, an estimate of annual mortality from predation by free-ranging 

domestic cats is 1.4-3.7 billion birds per year (Loss et al., 2013). Cat predation would predominantly 

affect small birds like songbirds. The mortality estimates are nationwide and not just for the northern 

GOM, where impacts would be much less. Impacts of collisions with vehicles and buildings and 

predation by domestic cats are expected to be moderate (chronic but not causing steady declines in 

whole large populations).

Emerging infectious diseases include West Nile virus. LaDeau et al. (2007) stated that 

“Emerging infectious diseases present a formidable challenge to the conservation of native species 

in the twenty-first century.” The population responses of bird species to the virus was complex 

(LaDeau et al., 2007). Of 20 selected avian species across North America that were potential hosts 

to the West Nile virus, 7 species (35%) exhibited negative changes at the population level that were 
Description of the Affected Environment and Impact Analysis 4-253

attributed to the virus, and only 2 of the 7 recovered to pre-West Nile virus levels by 2005 based on 

26 years of data (LaDeau et al., 2007). These continental estimates were meant to be qualitatively 

extrapolated to other species and can also be qualitatively extrapolated to the smaller area of the 

northern Gulf of Mexico (like the collision mortality estimates above). Impacts of the West Nile virus 

are at the population level and are expected to be major. 

Impacts of climate change (from global warming; refer to the Five-Year Program EIS 

(USDOI, BOEM, 2016b) and ocean acidification could eventually be expected to decline because, in 

April 2016, the United States joined a United Nations brokered agreement to keep the global 

temperatures within 2 °C (36 °F) of the pre-industrial climate, and preferably below 1.5 °C (35 °F). 

However, this might not occur if various positive feedbacks on global warming, such as a decrease 

in albedo of ice and snow shift to become irreversibly uncontrollable. Impacts on birds from 

greenhouse gases could be either beneficial or negative according to the Five-Year Program EIS 

(USDOI, BOEM, 2016b). Sea-level rise is discussed in Chapter 4.3 (Coastal Habitats). A recent 

comprehensive meta-analysis was completed on the impacts of ocean acidification on sea taxa 

(Kroeker et al., 2013). Some of the taxa are related to important prey for birds or are related to 

organisms that support ecosystems important to those birds. Of taxa related to organisms important 

to birds, some features of some of them are expected to be impacted negatively by ocean 

acidification, some positively impacted, and some not affected at all (Kroeker et al., 2013). Ocean 

acidification and changed nutrient supply into the continental shelf with eutrophication or deeutrophication (the latter owing to pollution control) have clear scope to alter phytoplankton 

succession, control phytoplankton, and support higher trophic levels (Flynn et al., 2015; Cripps et al., 

2016). Those levels could include secondary production mediated by copepods, future trophic 

dynamics, and probably positively or (more likely) negatively altered fisheries (Flynn et al., 2015; 

Cripps et al., 2016) and, therefore, perhaps altered waterbirds. Copepods could be affected 

indirectly through phytoplankton or directly by reduced pH (Cripps et al., 2016). Forecasted impact 

levels of climate change and ocean acidification from burning the hydrocarbons produced by a 

proposed action cannot be determined at this time. If not curtailed, climate change could possibly 

result in a decline in biodiversity that is vital to the ecosystems that support all bird life (McDaniel and 

Borton, 2002), and impacts could be as great as major; however, there is still a need for research on 

this. Global climate change may increase the frequency and intensity of hurricanes, which can 

cause spills from Gulf of Mexico OCS oil and gas facilities. Increases in the intensity, frequency, 

duration, and strength of Atlantic hurricanes are projected (USEPA, 2016d) but these might 

eventually respond to greenhouse gas control.

Cumulative incremental impacts to birds, when taking into consideration the potential 

impacts of OCS oil- and gas-related impacts, would be expected to be moderate as a result of a 

proposed action because of a possible large (e.g., ≥1,000 bbl) oil spill. This Multisale EIS does not 

consider a catastrophic spill. For a discussion of a low-probability catastrophic spill, refer to the 

Catastrophic Spill Event Analysis white paper (USDOI, BOEM (2017). Cumulative incremental 

impacts to birds, when taking into consideration the potential impacts of non-OCS oil- and 

gas-related impacts, would be expected to be major as a result of a proposed action. This is 

because of emerging non-native infectious diseases. Cumulative impacts could more likely have a 
4-254 Gulf of Mexico Multisale EIS

major impact on a particular bird species with a low population level, dependent upon the level of 

impact and the number of individuals affected by it (e.g., if an impact to the federally listed red knot 

or piping plover were to result in substantial mortality, it would diminish the continued viability of the 

population, including the annual rates of recruitment or survival).

4.8.2.4 Incomplete or Unavailable Information

BOEM has identified incomplete or unavailable information related to impacts on birds 

resulting from OCS oil- and gas-related activities and non-OCS oil- and gas-related activities in the 

GOM. BOEM’s subject-matter experts have used the available scientifically credible evidence 

presented below and applied accepted scientific methodologies to integrate existing information and 

extrapolate potential outcomes in completing this analysis and formulating the conclusions 

presented here.

The impact of artificial light along the coast on birds has not been studied and is unkown but 

is relevant to evaluating whether adverse impacts on the human environment are significant, but it is 

not essential to a reasoned choice among alternatives. BOEM used available information to fill the 

data gap. Existing information (Longcore and Rich, 2004) shows that outdoor lights at night can 

have both lethal impacts from collisions and sublethal impacts from a variety of mechanisms on 

birds. The impact level of obstruction lighting located on platforms would also need further study. 

The best available information was obtained from a study done by observers on platforms, from a 

model of energy reserves of migratory birds, and from several studies of the effect of light on birds. 

This scientific information presented in the “Routine Activities” section and under State oil and gas 

activities in the “Cumulative Impacts” section was used to conclude that platform lighting, in general, 

has minor impacts.

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

This chapter summarizes the potential impacts of routine activities, accidental events, and 

cumulative impacts associated with Alternative A on birds. Under Alternative A, BOEM would hold a 

regionwide lease sale comprised of the WPA, CPA, and a portion of the EPA.

Birds overlap with the proposed action area throughout their various life history stages. 

Different species have different feeding behaviors for different habitats. Many migrate seasonally 

and seabirds sometimes come to shore only to breed.

For impacts from routine activities, the effects from discharges and wastes, air and water 

quality, and noise would be negligible to coastal and migratory birds. Impacts of barotrauma from 

seismic airguns and platform severance with explosives would be minor. Impacts on trans-Gulf 

migrants from platform presence and lighting are tentatively minor but need further study of both 

positive and negative effects to be precisely assessed. For marine and coastal birds, more 

information on impact-producing factors for routine activites can be found in the Five-Year Program 

EIS (USDOI, BOEM, 2016b).
Description of the Affected Environment and Impact Analysis 4-255

An accidental event that may be associated with a proposed action and that has the largest 

impact on coastal and migratory birds is a large oil spill (≥1,000 bbl). Seabirds (compared with other 

bird groups) may not always experience the greatest impacts from a spill but may take longer to 

recover because of their unique population ecology (demography).

State oil- and gas-related activities would have the same impact-producing factors and 

expected impact levels as OCS oil- and gas-related activities. Discarding trash and debris would be 

a negligible impact. The hypoxic “dead zone” of the Mississippi River would have a minor impact. 

Net impacts of historic wetland loss and coastal wetland creation would be negligible. A large tanker 

spill (≥1,000 bbl) would have moderate impacts. Military activities would have minor impacts. 

Nonconsumptive recreation would have minor impacts. Consumptive recreation with any hunting 

regulation mitigation would have negligible impacts. Boat traffic would have a negligible impact on 

wetland bird habitat. Impacts of collisions with vehicles and buildings as well as predation by 

domestic cats would be moderate. Impacts of the West Nile virus and future emerging infectious 

diseases are at the population level. Partly because of this, the impacts, including the incremental 

contribution of a proposed lease sale, are expected to be major. Impacts of commercial fishing are 

expected to be positive for discarded fish and invertebrate bycatch and negligible for seabird 

bycatch. Impacts of climate change and ocean acidification cannot be determined at this time. 

Finally, impacts of wetland subsidence are expected to be moderate. The overall impacts from a 

proposed action on coastal and migratory birds are moderate. The incremental contribution of a 

proposed action to the overall cumulative impacts is considered moderate, but only because of the 

potential impacts of a large oil spill (≥1,000 bbl). However, the combined probabilities of a large oil 

spill for occurrence and also contact with shoreline birds and nearshore waterbirds under 

Alternative A are small (<0.5-20% after 10 days and <0.5-25% after 30 days) (refere to Chapter 

3.2.1.4.8 and Appendix E). These probabilities are for the high case for projected resource 

estimates (billions of barrels of oil). The overall cumulative impacts to non-OCS oil- and gas-related 

anthropogenic events and natural processes are considered major, but only because of the impact 

of non-native infectious diseases.

From a bird perspective, since Alternative A is regionwide, which includes the WPA, CPA, 

and EPA portions of the proposed lease sale area, it would have more of all of the types of OCS oiland gas-related activities; therefore, it would have more potential for impacts. Impacts from the 

other alternatives would follow in a graded fashion. For platforms, the number of spills between 

1,000 and 10,000 bbl that has been forecasted to potentially occur is <1 spill for Alternatives A, B, 

and C (i.e., spill); also for platforms, the number of spills ≥10,000 bbl has also been estimated to be 

<1 spill for Alternatives A, B, and C. For pipelines, the number of spills between 1,000 and 9,999 bbl 

has been estimated to be <1 to 1 spill for Alternative A; also for pipelines, the number of spills 

≥10,000 bbl has been estimated to be <1 spill for Alternative A.
4-256 Gulf of Mexico Multisale EIS

4.8.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Under Alternative B, BOEM would hold a lease sale excluding the WPA available lease sale 

blocks and offer all available blocks in the CPA and a portion of the EPA. The impacts to birds from 

Alternative B are similar to those from Alternative A since a majority of the activity is projected to 

occur in the CPA, as described in Chapter 3.1, and since overall routine and accidental impacts are 

considered moderate, but only because of the impacts of a large oil spill (≥1,000 bbl). The 

combined probabilities for occurrence and contact with shoreline birds and nearshore waterbirds are 

small. The incremental cumulative impacts of Alternative B to OCS oil- and gas-related impacts are 

considered moderate, but only because of the impacts of a large oil spill (≥1,000 bbl). 

The following description of migratory routes applies to Alternatives A, B, and C and refers to 

adult trans-Gulf migrant birds stopping over on platform and drilling vessels. In spring, under East 

Continental High synoptic wind conditions, the migrant birds mostly follow a northward migratory 

route that crosses the western GOM, especially in the WPA (refer to Figure 4-20). In spring, under 

Bermuda High synoptic wind conditions, the migrant birds follow a northern migratory route that 

crosses the north-central GOM across both the WPA and EPA (refer to Figure 4-21). In fall, under 

East Continental High synoptic wind conditions, such birds mostly follow a fall southward migratory 

route that crosses mostly outside the western GOM, especially outside the WPA (refer to Figure

4-20). During Bermuda High wind conditions, birds mostly do not migrate in the fall (Russell, 2005).

Migrant birds stop over on GOM offshore structures in fall, collide with the structures, and 

exhibit nocturnal circulation just like in the spring (Russell, 2005), even though they are just 

beginning their nonstop flight in the fall. Drilling vessels and new platforms under Alternative B 

would be entirely outside the western Gulf. Therefore, under Alternative B, both positive and 

negative impacts from offshore structures on trans-Gulf migrants migrating during an East 

Continental High in spring would be less than under Alternative C, and in fall, the impacts would be 

more than under Alternative C (refer to Figure 4-20). Under Alternative B, both positive and 

negative impacts from offshore structures on trans-Gulf migrants migrating during a Bermuda High in 

spring would be about the same as under Alternative C (refer to Figure 4-21). Under Alternative B, 

juvenile trans-Gulf southward fall migration often differs from adult migration in that it often hugs the 

Texas coast. It is possible that juveniles lack the reserves for nonstop overwater flight. In any case, 

they would possibly stop over on platforms on the OCS near the Texas coast, and the leasing area 

under Alternative C (i.e., the WPA) is off the Texas coast. The leasing area for Alternative B is the 

CPA/EPA. Therefore, both positive and negative impacts on juveniles would occur under Alternative 

C but not under Alternative B. The overall cumulative impacts to non-OCS oil-and gas-related 

anthropogenic events and natural processes are considered major, but only because of the 

anthropogenic impact of non-native infectious diseases. The significance of impact-producing 

factors on birds would be the same for Alternative B as for Alternative A. The degree of impacts as 

a result of Alternative B would be somewhat less than Alternative A since a majority of the routine 

activities and impact-producing factors from a proposed lease sale would occur in the CPA/EPA, as 

projected in the scenario in Chapter 3.1.1. For platforms, the number of spills between 1,000 and 
Description of the Affected Environment and Impact Analysis 4-257

9,999 bbl has been estimated to be <1 spill for Alternative B; also for platforms, the number of spills 

≥10,000 bbl has also been estimated to be <1 spill for Alternative B. For pipelines, the number of 

spills between 1,000 and 9,999 bbl has been estimated to be <1 spill for Alternative B. Therefore, 

the overall impacts of Alternative B on coastal and migratory birds would also be moderate and the 

incremental contribution to the overall cumulative impacts would also be moderate, but only 

because of the potential impacts a potentially forecasted to occur large oil spill (≥1,000 bbl). 

However, under Alternative B ,the combined probabilities of a large oil spill for occurrence and also 

contact with shoreline birds and nearshore waterbirds are small (<0.5-20% after 10 days and 

<0.5-25% after 30 days) (refer to Chapter 3.2.1.4.8 and Appendix E). These probabilities are for 

the high case for projected resource estimates (billions of barrels of oil).

4.8.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Under Alternative C, BOEM would hold a lease sale excluding the CPA/EPA available lease 

blocks and offer all available blocks in the WPA. The impacts to birds from OCS oil-and gas-related 

activities are similar in the WPA or wherever they may occur in the GOM, and overall routine and 

accidental impacts from Alternative C are considered moderate, but only because of the impacts of 

a large oil spill (≥1,000 bbl).

While the WPA is a smaller area with less projected activity than is proposed for the 

CPA/EPA (refer to Chapter 3), offshore pelagic seabird habitat is distributed throughout the planning 

areas. Therefore, activities isolated to specific planning areas pose similar potential impacts to 

offshore pelagic seabird populations as do activities occurring in all planning areas. Therefore, 

because of the diversity and distribution of offshore pelagic seabird species in the Area of Interest, 

the level of impacts would be the same for Alternatives A, B, C, and D.

Trans-Gulf migrant birds stopping over on platforms and drilling vessels follow the migratory 

routes described in Chapter 4.8.2.2 (Alternative B) and as shown in Figures 4-20, 4-21, and 4-24. 

Migrant birds stop over on GOM offshore structures in fall, collide with the structures, and exhibit 

nocturnal circulation just like in the spring (Russell, 2005), even though they are just beginning their 

nonstop flight in the fall. Drilling vessels and new platforms under Alternative C would be entirely 

outside the eastern and central GOM; therefore, both positive and negative impacts from offshore 

structures on trans-Gulf migrants migrating during an East Continental High in spring would be more 

than under Alternative B, and in fall, the impacts would be less than under Alternative B (refer to 

Figure 4-20). However, under Bermuda High synoptic wind conditions in spring, migration would be 

mostly across the north-central GOM, overlapping both the WPA and CPA (refer to Figure 4-21); 

therefore, both the favorable and unfavorable impacts to trans-Gulf migrants extant under 

Alternative C under Bermuda High conditions in spring would be about the same as under 

Alternative B. Juvenile trans-Gulf southward fall migration often differs from adult migration in that it 

often hugs the Texas coast. It is possible that juveniles lack the reserves for nonstop overwater 

flight. In any case, they would possibly stop over on platforms on the OCS near the Texas coast, 

and the leasing area under Alternative C (i.e., the WPA) is off the Texas coast; therefore, both 
4-258 Gulf of Mexico Multisale EIS

positive and negative impacts on juveniles would occur under Alternative C. For platforms, the 

number of spills between 1,000 and 9,999 bbl has been estimated to be <1 for Alternatives C; also 

for platforms, the number of spills ≥10,000 bbl has also been estimated to be <1 for Alternative C.

Alternative C would have the same potential for impact as Alternative A or B, even though 

the level of projected OCS oil- and gas-related activities and impact-producing factors are less in the 

WPA, but these are still substantial. For example, a range of 11-67 production wells are projected to 

be drilled and developed under Alternative C, whereas 58-464 production wells are projected to 

occur under Alternative B. The incremental cumulative impacts of Alternative C to OCS oil- and gasrelated anthropogenic events are considered moderate, but only because of the impacts of a large 

oil spill (≥1,000 bbl) potentially forecasted to occur. However, under Alternative C, the combined 

probabilities of a large oil spill for occurrence and also contact with shoreline birds and nearshore 

waterbirds are small (<0.5-5% after 10 days and <0.5-7% after 30 days) (refer to Chapter 3.2.1.4.8 

and Appendix E) These probabilities are for the high case for projected resource estimates (billions 

of barrels of oil).

The significance of impact-producing factors on birds would be somewhat the same for 

Alternative C as for Alternative A. Alternative C would have a somewhat less impact than 

Alternatives A and B since the geographical planning area is smaller and less activity is projected to 

occur in the WPA under the scenario in Chapter 3.1.1. 

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

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

Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, the impacts to birds are similar wherever they may occur in the GOM, 

and overall routine and accidental impacts are considered moderate, but only because of the 

impacts of a large oil spill (≥1,000 bbl). The incremental cumulative impacts of Alternative D to OCS 

oil- and gas-related anthropogenic events are considered moderate, but only because of the 

impacts of a large oil spill (≥1,000 bbl). Also, the incremental impacts of Alternative D on other nonOCS oil-and gas-related anthropogenic events and natural processes are considered major, but 

only because of the anthropogenic impact of non-native infectious diseases. The significance of 

impact-producing factors on birds could be somewhat less for Alternative D than for Alternative A, B, 

or C since a few blocks and associated activities would be removed from the proposed lease sale 

area. However, since there are so few unleased blocks subject to the Topographic Features, Live 

Bottom, and Blocks South of Baldwin County, Alabama, Stipulations, this would be a small 

incremental change compared with the other action alternatives. The impacts under Alternative D 

would not be much different and likely not even measurable when compared with the other action 

alternatives.

4.8.2.9 Alternative E—No Action

Alternative E would offer no new lease blocks for exploration and development; therefore, no 

impacts from a proposed lease sale would occur. However, there would be continuing impacts 
Description of the Affected Environment and Impact Analysis 4-259

associated with the existing oil and gas activities from previously permitted activities and previous 

lease sales.

Overall, cumulative impacts on birds are as much as major and would result in social 

endpoints of take under the Migratory Bird Treaty Act and impacts on bird watching and hunting. 

There would consequently be fewer consumers in the supply chain and reduced spending. Hunting 

results in additional negative feedback loops for economic factors.

4.9 PROTECTED SPECIES

The Endangered Species Act of 1973 (ESA), as amended, establishes a national policy 

designed to protect and conserve threatened and endangered species and the ecosystems upon 

which they depend. In fulfilling these requirements, each agency must use the best scientific and 

commercial data available. The FWS and NMFS share responsibility for implementing the ESA.

The Marine Mammal Protection Act of 1972 (MMPA) prohibits, with certain exceptions, the 

"take" of marine mammals in U.S. waters and by U.S. citizens on the high seas and the importation 

of marine mammals and marine mammal products into the U.S. The NMFS and FWS are also 

responsible for the MMPA.

For the GOM, NMFS is charged with protecting all cetaceans while manatees are under the 

jurisdiction of FWS. Details on BOEM’s consultations and coordination are presented in 

Chapter 5.7 (Endangered Species Act).

Protected species for the purposes of this Multisale EIS include ESA- and MMPA-listed 

species and associated designated critical habitat under the ESA. The species considered in this 

chapter, pursuant to our consultations and coordination, and within Table 4-17 are those that could 

be affected within the GOM Area of Interest and that are subject to the proposed activities under the 

alternatives. For those species not considered further because they are unlikely to be affected by 

the proposed activities, refer to Appendix F. Critical habitats noted within the GOM Area of Interest 

are shown in Figure 4-25 and are mentioned in this chapter, but comprehensive details on many of 

these habitats can be found in Chapters 4.3 (Coastal Habitats), 4.5 (Sargassum and Associated 

Communities), and 4.6 (Live Bottom Habitats).

Table 4-17. Species within the Gulf of Mexico That Are Protected Under the Endangered Species Act 

and/or the Marine Mammal Protection Act.

Common Name Scientific Name Common Name Scientific Name

Marine Mammals Sea Turtles

Atlantic spotted 

dolphin* Stenella frontalis* Green sea turtle2 Chelonia mydas2

Blainville’s beaked 

whale*

Mesoplodon 

densirostris* Hawksbill sea turtle3 Eretmochelys imbricata3

Bottlenose dolphin* Tursiops truncatus* Kemp’s ridley sea turtle3 Lepidochelys kempii3

Bryde’s whale* Balaenoptera edeni* Northwest Atlantic Ocean 

loggerhead sea turtle2 Caretta caretta2
4-260 Gulf of Mexico Multisale EIS

Clymene dolphin* Stenella clymene* Leatherback sea turtle

(Atlantic Northwest)3 Dermochelys coriacea3

Cuvier’s beaked whale* Ziphius cavirostris* Beach Mice

Dwarf sperm whale* Kogia sima* Alabama beach mouse3 Peromyscus polionotus 

ammobates3

False killer whale* Pseudorca 

crassidens*

Choctawhatchee beach 

mouse3 Peromyscus polionotus allophrys3

Fraser’s dolphin* Lagenodelphis hosei* Perdido Key beach 

mouse3

Peromyscus polionotus 

trissyllepsis3

Gervais’ beaked whale* Mesoplodon 

europaeus* St. Andrew beach mouse3 Peromyscus polionotus peninsularis3

Killer whale* Orcinus orca* Birds

Melon-headed whale* Peponocephala 

electra*

Cape Sable Seaside 

Sparrow3

Ammodramus 

maritimus mirabilis3

Pantropical spotted 

dolphin* Stenella attenuate* Mississippi Sandhill Crane3 Grus canadensis pulla3

Pygmy killer whale* Feresa attenuata* Piping Plover2 Charadrius melodus2

Pygmy sperm whale* Kogia breviceps* Rufa Red knot2 Calidris canutus rufa2

Risso’s dolphin* Grampus griseus* Roseate Tern2 Sterna dougallii 

dougallii2

Rough-toothed dolphin* Steno bredanensis* Whooping Crane3 Grus americana3

Short-finned pilot 

whale*

Globicephala 

macrorhynchus* Wood Stork2 Mycteria americana2

Sperm whale1 Physeter 

macrocephalus1 Corals

Spinner dolphin* Stenella longirostris* Elkhorn coral2 Acropora palmata2

Striped dolphin* Stenella coeruleoalba* Staghorn coral2 Acropora cervicornis2

West Indian manatee1 Trichechus manatus1 Boulder star coral2 Orbicella franksi2

Lobed star coral2 Orbicella annularis2

Mountainous star coral2 Orbicella faveolata2

* This species is protected under the Marine Mammal Protection Act (MMPA). 1 This species/subspecies is listed under the Endangered Species Act (ESA) as 

“endangered” and is also protected under the MMPA. 2 This species/subspecies is listed under the ESA as “threatened.” 

3 This species/subspecies is listed under the ESA as “endangered.”
Description of the Affected Environment and Impact Analysis 4-261 Description of the Affected Environment and Impact Analysis 4-261 Description of the Affected Environment and Impact Analysis 4-261 Description of the Affected Environment and Impact Analysis 4-261

Figure 4-25. Gulf of Mexico Protected Species’ Critical Habitats.
4-262 Gulf of Mexico Multisale EIS

Impact-Level Definitions

As the routine activities, accidental events, and cumulative impacts are considered for 

specific listed species, each is given criteria per level of impact represented below.

• Negligible – An individual or group of animals would be subject to nominal to 

slight measurable impacts. No mortality or injury to any individual would occur, 

and no disruption of behavioral patterns would be expected. The disturbance 

would last only as long as the human-caused stimulus was perceptible to the 

individual or group.

• Minor – An individual or group of animals would be subject to a human-caused 

stimulus and be disturbed, resulting in an acute behavioral change. No mortality 

or injury to an individual or group would occur.

• Moderate – An individual or group of animals would be subject to a humancaused stimulus and be disturbed, resulting in a chronic behavioral change. 

Individuals may be impacted but at levels that do not affect the fitness of the 

population. Some impacts to individual animals may be irreversible.

• Major – An individual or group of animals would be subject to a human-caused 

stimulus, resulting in physical injury or mortality, and would include sufficient 

numbers that the continued viability of the population is diminished, including 

annual rates of recruitment or survival. Impacts would also include permanent 

disruption of behavioral patterns that would affect a species or stock.

The analyses of the reasonably foreseeable potential impacts of routine activities and 

accidental events associated with a GOM proposed action and a proposed action’s incremental 

contribution to the cumulative impacts are presented in detail within the chapters below. The 

approach of the analysis is to focus on the potential impact-producing factors from OCS oil- and gasrelated routine activities (i.e., exploration, development, and production), as well as accidental 

events and cumulative impacts, and to define impact-level measures for each impact-producing 

factor for protected species, as summarized in Table 4-18. These impacts are across all action 

alternatives (i.e., Alternatives A, B, C, and D) except for beach mice and protected corals. Beach 

mice are not found in the WPA; therefore, they are not relevant for Alternative B, and the ranges 

given for potential impacts to protected corals are based on whether or not stipulations are placed on 

leases.
Description of the Affected Environment and Impact Analysis 4-263

Table 4-18. Protected Species Impact-Producing Factors That Are Reasonably Foreseeable.

Protected Species Magnitude of Potential Impact1

Impact-Producing 

Factors

Marine 

Mammals Sea Turtles Beach Mice2

Protected 

Birds

Protected 

Corals3 

Routine Impacts

Geological and 

Geophysical Activities

Negligible to Negligible to N/A* N/A N/A

Moderate Moderate

Transportation

(vessel strikes) Negligible Negligible N/A N/A N/A

Discharges

(air and water quality

degradation)

Negligible Negligible N/A Negligible N/A

Decommissioning

(explosive severance)

Negligible to Negligible to N/A N/A Negligible Minor Moderate

Noise Negligible to Negligible to N/A Negligible N/A

Minor Minor

Drilling and Exploration 

(bottom-disturbing 

activities)

N/A N/A N/A N/A Negligible

Offshore 

Lighting/Platform 

Presence

N/A N/A N/A Negligible N/A

Vessel Operation 

(bottom-disturbing 

activities)

N/A N/A N/A N/A Negligible

Accidental Impacts

Oil Spills4 Negligible to Negligible to Negligible Negligible to Negligible Moderate Moderate Moderate

Oil-Spill Response 

Activities

Negligible to Negligible to Negligible Negligible to Negligible Minor Minor Minor

Marine Trash and 

Debris Negligible Negligible Negligible Negligible Negligible

Cumulative Impacts

Incremental 

Contribution5 Negligible Negligible Negligible Negligible Negligible

OCS Oil and Gas6 Negligible to Negligible to Negligible Negligible to Negligible Moderate Moderate Moderate

Non-OCS Oil and Gas7 Negligible to

Major

* N/A represents those impact-producing factors that are not applicable to that protected species group.

1 The analysis supporting these conclusions are discussed in detail in the analysis chapter for each 

species. 

2 Beach mice are not found in the WPA; therefore, they are not likely to be impacted by Alternative B.

3 Ranges for the potential impacts to protected corals are based on whether or not protected stipulations

are placed on leases.

4 Accidental oil spills are those <10,000 bbl.
4-264 Gulf of Mexico Multisale EIS

5 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

6 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

7 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

For protected coral impact-producing factors, refer to Table 4-11 in Chapter 4.6.1

(Topographic Features) since coral impact-producing factors are covered in detail there and would 

apply to protected corals as well. For protected birds impact-producing factors, refer to Table 4-16

in Chapter 4.8 (Birds) since the impact-producing factors that impact coastal, marine, and migratory 

birds (the listed birds are either found in coastal areas or are migratory and utilize coastal areas as 

part of their life history) are covered in detail there. For beach mice, the most relevant impactproducing factors are those causing harm to the populations by affecting their habitat (beaches). 

Table 4-10 in Chapter 4.3.2 (Coastal Barrier Beaches and Associated Dunes) covers the impactproducing factors that affect beaches and dunes, and details about those impacts to beach mouse 

habitat can be found there.

BOEM understands that mitigations greatly reduce the likelihood of an impact-producing 

factor, but mitigations do not guarantee that a protected species would not be impacted. There is a 

very low probability that a protected species may not be sighted despite all of the mitigative 

precautions taken to reduce impact. Unlikely scenarios such as these may cause major impacts to a 

protected species with a very low population because some impact-producing factors may negatively 

impact the reproductive success of an individual and, therefore, the continued viability of the 

population. However, based on credible scientific research and that within the GOM, there is a longstanding and well-developed OCS Program (more than 60 years), and scenarios such as these are 

highly speculative. There are no data to suggest that activities from the previous OCS Programs are 

significantly impacting protected species populations. Therefore, for purposes of this analysis, 

BOEM has considered the potential effects of impact-producing factors that are reasonably 

foreseeable to occur.

Current baselines (including past and present events) are described for all protected species 

under their respective “Description of the Affected Environment” chapters. The altered baseline 

includes individual species directly affected by this unexpected unique catastrophic event. BOEM 

understands that each oil-spill event is unique and that its outcome depends on several factors, 

including the time of year and location of the release relative to winds, currents, land, and sensitive 

resources, as well as specifics of the well and response effort. Specific to the Deepwater Horizon, 

the Trustees have completed the PADARP/PEIS (Deepwater Horizon Natural Resource Damage 

Assessment Trustees, 2016), which has the purpose and need of assessing and creating restoration 

plans to relieve injuries from the to natural resourses and services. The injuries assessed within the 

PDARP/PEIS do not necessarily equate the baseline as defined by NEPA. BOEM continues to 

analyze the Deepwater Horizon explosion, oil spill, and response Deepwater Horizon explosion, oil 
Description of the Affected Environment and Impact Analysis 4-265

spill, and response as information becomes available, and it was evaluated as part of the baseline 

for resources in this Multisale EIS.

BOEM analyzed a low-probability catastrophic event (USDOI, BOEM 2017) in conjunction 

with its analysis of the potential effects, as requested by CEQ pursuant to its regulation at 40 CFR § 

1502.22. The CEQ (2010) recommended that BOEM should “ensure that NEPA documents provide 

decision makers with a robust analysis of reasonably foreseeable impacts, including an analysis of 

reasonably foreseeable impacts associated with low probability catastrophic spills for oil and gas

activities on the Outer Continental Shelf.” A low-probability catastrophic spill is, by definition, not

reasonably certain to occur. The return period of a catastrophic oil spill in OCS areas is estimated to 

be 165 years, with a 95 percent confidence interval between 41 years and more than 500 years 

(Ji et al., 2014). Other methods of analysis are significantly limited in their applicability and 

availability, and they would not provide any meaningful or useful information to be used to assess 

the risk of a catastrophic oil-spill occurrence at this programmatic level of oil and gas activities in the 

GOM.

4.9.1 Marine Mammals

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

GOM, including northern U.S. waters. The GOM’s Cetacea include the suborders Mysticeti (i.e., 

baleen whales) and Odontoceti (i.e., toothed whales), and the order Sirenia, which includes the West 

Indian manatee. Most marine mammal distributions vary widely across the northern GOM with very 

little known about their respective breeding and calving grounds, as well as any potential migratory 

routes. While all marine mammals are protected under the MMPA, two species (i.e., the sperm 

whale and West Indian manatee) are listed as endangered under the ESA due to various factors, 

which are described in this chapter. For the Gulf of Mexico, NMFS is charged with protecting all 

cetaceans, while manatees are under the jurisdiction of FWS. Details on BOEM’s consultations and 

coordination are presented in Chapter 5.7 (Endangered Species Act).

The analyses of the reasonably forseeable potential impacts of routine activities and 

accidental events associated with a proposed lease sale and a proposed lease sale’s incremental 

contribution to the cumulative impacts to marine mammals are presented in this chapter. Potential 

impact-level criteria are defined in Chapter 4.9 (Protected Species) and apply to marine mammal 

species described in this chapter. The approach of the analysis is to focus on the potential impactproducing factors from OCS oil- and gas-related routine activities (i.e., exploration, development, 

and production), as well as accidental events and cumulative impacts, and to define impact-level 

measures for each impact-producing factor in relation to the best available population estimates 

(refer to Table 4-18 in Chapter 4.9). Some impact-producing factors may have different potential 

impact levels to different marine mammal species due to their various population sizes, as well as 

their wide-ranging behavior; thus, some potential impact-producing factors are described in a range. 

Throughout this chapter, where information was incomplete or unavailable, BOEM complied with its 

obligations under NEPA to determine if the information was relevant to reasonably foreseeable 

significant adverse impacts. Refer to Chapter 4.9.1.2.4 for a more detailed discussion.
4-266 Gulf of Mexico Multisale EIS

4.9.1.1 Description of the Affected Environment

Twenty-one species of cetaceans and one species of sirenian (West Indian manatee) 

regularly occur in the GOM and are identified in NMFS’ Gulf of Mexico Stock Assessment Reports 

(Jefferson et al., 1992; Davis et al., 2000; Waring et al., 2016). Along with stock assessment 

reports, NMFS also calculates the Potential Biological Removal (PBR) for cetaceans, which is 

defined under the MMPA as the maximum number of animals, not including natural mortalities, that 

may be removed from a marine mammal stock while allowing that stock to reach or maintain its 

optimum sustainable population (USDOC, NMFS, 2007b). The PBR is the product of the minimum 

population estimate of the stock, one-half the maximum theoretical or estimated net productivity rate 

of the stock at a small population size, and a recovery factor of between 0.1 and 1.0 (USDOC, 

NMFS, 2007b). The PBR can be used as a conservative tool, most often for commercial fisheries, to 

help with management of the different marine mammal stocks because a potential impact-producing 

factor may have a more serious impact on a marine mammal stock that has a lower PBR and a less 

serious impact to a marine mammal stock with a higher PBR.

There are species that have been reported from GOM waters either by sighting or stranding 

that, due to their rarity, are not considered in this Multisale EIS (Wursig et al., 2000; Mullin and 

Fulling, 2004). These species include the following: the blue whale (Balaenoptera musculus), North 

Atlantic right whale (Eubalaena glacialis), and Sowerby’s beaked whale (Mesoplodon bidens), all of 

which are considered extralimital in the Gulf of Mexico; and the humpback whale (Megaptera 

novaeangliae), fin whale (Balaenoptera physalus), sei whale (Balaenoptera borealis), and minke 

whale (Balaenoptera acutorostrata), all of which are considered rare occasional migrants in the Gulf 

of Mexico (Wursig et al., 2000; Mullin and Fulling, 2004). Because these species are uncommon in 

the GOM and because they are not included in the most recent NMFS Gulf of Mexico Stock 

Assessment Reports, BOEM did not consider them for this analysis as they are unlikely to be 

impacted by OCS oil- and gas-related activities.

Population estimates for marine mammals in the GOM, as well as the PBR for cetaceans, 

are represented in Table 4-19. A recent study analyzed past cetacean survey data and 

environmental variables related to cetacean habitat (e.g., sea-surface temperature and bathymetry) 

to produce cetacean density models for the Gulf of Mexico (Roberts et al., 2016). However, 

because NMFS is charged with protecting cetaceans in the GOM waters, BOEM used NMFS’ Stock 

Assessment Reports for this analysis. The most recent abundance estimates available for all 

cetacean species mentioned in this Multisale EIS can be found on NMFS’s website (USDOC, NMFS, 

2015b). and estimates for manatees can be found on the Florida Fish and Wildlife Conservation 

Commission’s website (State of Florida, Fish and Wildlife Conservation Commission, 2015a).
Description of the Affected Environment and Impact Analysis 4-267

Table 4-19. Best Available Population Estimates for Marine Mammal Species in the Northern Gulf of 

Mexico.

Species Population Estimate PBR*

Bryde’s Whale (Balaenoptera brydes) 33 0.03

Sperm Whale (Physeter macrocephalus) 763 1.1

Pygmy Sperm Whale (Kogia breviceps) 186a 0.9

Dwarf Sperm Whale (Kogia sima) 186a 0.9

Gervais’ Beaked Whale (Mesoplodon europaeus) 149b 0.8

Blainville’s Beaked Whale (Mesoplodon densirostris) 149b 0.8

Cuvier’s Beaked Whale (Ziphius cavirostris) 74 0.4

Bottlenose Dolphin (Tursiops truncatus)

Oceanic waters

Northern Coastal Stock

Eastern Coastal Stock

Western Coastal Stock

Continental Shelf Stock

Bay, Sound, and Estuary (27 stocks)

Barataria Bay Estuarine System

Mississippi Sound, Lake Borgne, and Bay 

Boudreau

5,806

7,185

12,388

20,161

51,192

Unknown 

for all but 6 stocks 

Unknown

901

42

60

111

175

469

Undetermined 

for all but 6 stocks

Undetermined

5.6

Clymene Dolphin (Stenella clymene) 129 0.6

Pantropical Spotted Dolphin (Stenella attenuata) 50,880 407

Atlantic Spotted Dolphin (Stenella frontalis) Unknown Undetermined

Risso’s Dolphin (Grampus griseus) 2,442 16

Rough-toothed Dolphin (Steno bredanensis) 624 3

Spinner Dolphin (Stenella longirostris) 11,441 62

Striped Dolphin (Stenella coeruleoalba) 1,849 10

False Killer Whale (Pseudorca crassidens) Unknown Undetermined

Fraser’s Dolphin (Lagenodelphis hosei) Unknown Undetermined

Killer Whale (Orcinus orca) 28 0.1

Melon-headed Whale (Peponocephala electra) 2,235 13

Pygmy Killer Whale (Feresa attenuata) 152 0.8

Short-finned Pilot Whale (Globicephala 

macrorhynchus)

c 2,415 c 15 c

West Indian Manatee (Trichechus manatus latirostris) 2,730 d Not Applicable e
4-268 Gulf of Mexico Multisale EIS

Species Population Estimate PBR*

* Potential Biological Removal (PBR) estimates from Waring et al., 2016. a This estimate includes both the dwarf and pygmy sperm whales.

b This estimate includes Gervais’ beaked whales and Blainville’s beaked whales in the GOM. c This estimate includes all Globicephala sp., though it is presumed that only short-finned pilot whales 

are present in the Gulf of Mexico.

d This estimate includes the west coast of Florida. e West Indian manatees are under the jurisdiction of FWS. The NMFS PBR estimate is not applicable.

Sources: State of Florida, Fish and Wildlife Conservation Commission, 2015a.

Waring et al., 2016.

Threatened or Endangered Species

Currently, the sperm whale (Physeter macrocephalus) and the West Indian manatee 

(Trichechus manatus) are the only ESA-listed marine mammals that regularly occur in the GOM. 

The sperm whale is common in oceanic waters of the northern GOM and appears to be a resident 

species (Mullin et al., 1991; Davis and Fargion, 1996; Jefferson and Schiro, 1997). The West Indian 

manatee is commonly found along the coast of Florida in the winter and may migrate as far as Texas 

in the warmer seasons, typically inhabiting only shallow coastal marine, brackish, and freshwater 

areas (O’Shea et al.,1995; Fertl et al., 2005). The FWS provided notice of the petition on January 8, 

2016, to reclassify the West Indian manatee from endangered to threatened (Federal Register, 

2016d). If this petition becomes a final rule and the West Indian manatee meets the requirements to 

be reclassified as threatened, it would still have protection under the ESA because it would still be 

an ESA-listed species. On December 8, 2016, NMFS announced a 12-month finding on a petition to 

list the GOM Bryde’s whale (Balaenoptera edeni) and proposed that it be listed as endangered 

under the ESA (Federal Register, 2016e). If NOAA issues a final rule listing the Bryde’s whale as 

endangered, the species will receive additional protections and Federal agencies will be required to 

consult under Section 7 for Federal actions that may affect the species. 

Cetaceans—Odontocetes

The sperm whale was listed as endangered in 1970 (Federal Register, 1970a). It is found 

worldwide in deep waters between approximately 60° N. and 60° S. latitude (Whitehead, 2002), 

although generally only large males venture to the extreme northern and southern portions of their 

range (Jefferson et al., 1993). Females and juveniles form pods that are found mainly at tropical and 

temperate latitudes (between 50° N. and 50° S. latitude), while the solitary adult males can be found 

at higher latitudes (between 75° N. and 75° S. latitude) (Reeves and Whitehead, 1997). In the 

western North Atlantic, they range from Greenland to the Gulf of Mexico and the Caribbean Sea. As 

deep divers, sperm whales generally inhabit oceanic waters at depths greater than 591 ft (180 m), 

but they do come close to shore where submarine canyons or other geophysical features bring deep 

water near the coast (Jefferson et al., 1993). Sperm whales prey on cephalopods, demersal fishes, 

and benthic invertebrates (Rice, 1989; Jefferson et al., 1993).
Description of the Affected Environment and Impact Analysis 4-269

The NMFS considers sperm whales in the GOM as a distinct stock in the Marine Mammal

Stock Assessment Report (Waring et al., 2016), and research supports this distinction from the 

Atlantic and Caribbean stocks (Engelhaupt et al., 2009; Gero et al., 2007; Jaquet, 2006; Jochens 

et al., 2008). Consistent sightings, satellite tracking, strandings, historical whale catches, and recent 

research indicate that sperm whales occupy the northern GOM throughout all seasons and that 

aggregations are commonly found in waters over the shelf edge in the vicinity of the Mississippi 

River Delta, which are 1,641-6,562 ft (500-2,000 m) in depth, and represent a resident population 

(Mullin et al., 1994a; Davis and Fargion, 1996; Sparks et al., 1996; Jefferson and Schiro, 1997; 

Davis et al., 2000; Jochens et al., 2008). Seasonal aerial surveys confirmed that sperm whales 

sightings are more common during summer (Mullin et al., 1991 and 1994a; Mullin and Hoggard, 

2000; Mullin and Fulling, 2004), but this may be an artifact of movement patterns of sperm whales 

associated with reproductive behavior, hydrographic features, or other environmental or seasonal 

factors. Because of the lack of adult males observed in the GOM, it is not known whether females 

leave the GOM to mate or whether males sporadically enter the area to mate with females, which 

would make this a very important area for sperm whale reproduction. 

While they may be encountered almost anywhere on the high seas, their distribution shows a 

preference for continental margins, sea mounts, and areas of upwelling, where food is abundant 

(Leatherwood and Reeves, 1983). The low-salinity, nutrient-rich water from the Mississippi River 

contributes to enhanced primary and secondary productivity in the north-central GOM and may 

explain the presence of sperm whales in the area (Würsig et al., 2000; Davis et al., 2000 and 2002; 

Jochens et al., 2008). The continental margin in the north-central GOM is only 12 mi (20 km) wide at 

its narrowest point, and the ocean floor descends quickly along the continental slope, reaching a 

depth of 3,281 ft (1,000 m) within 25 mi (40 km) of the coast. This unique area of the GOM brings 

deepwater organisms within the influence of coastal fisheries, contaminants, and other human 

impacts on the entire northern GOM (Davis et al., 2000). Sperm whales are noted for their ability to 

make prolonged deep dives and are likely the deepest and longest diving mammal. Typical foraging 

dives last approximately 40 minutes and descend to about 1,312 ft (400 m), followed by 

approximately 8 minutes of resting at the surface (Papastavrou et al., 1989). However, dives of over 

2 hours and deeper than 2.1 mi (3.3 km) have been recorded (Clarke, 1976; Watkins et al., 1985 

and 1993), and individuals may spend extended periods of time at the surface to recover.

Evidence suggests that the disproportionately large head of the sperm whale is an 

adaptation to produce vocalizations (Norris and Harvey, 1972; Cranford, 1992). This suggests that 

vocalizations are extremely important to sperm whales. The function of vocalizations is relatively 

well-studied (Weilgart and Whitehead, 1997; Goold and Jones, 1995). Long series of monotonous, 

regularly spaced clicks are associated with feeding and are thought to be produced for echolocation. 

Sperm whales also use unique stereotyped click sequence “codas” (Mullins et al., 1988; Watkins 

and Scheville, 1977; Watkins et al., 1985), according to Weilgart and Whitehead (1988), to possibly 

convey information about the age, sex, and reproductive status of the sender. Groups of closely 

related females and their offspring have group-specific dialects (Weilgart and Whitehead, 1997). 

Sperm whale vocalization and audition are important for echolocation and feeding, social behavior 

and intragroup interactions, and maintaining social cohesion within the group. Further detailed 
4-270 Gulf of Mexico Multisale EIS

information on sperm whale hearing may be found in BOEM’s Atlantic OCS Proposed Geological 

and Geophysical Activities: Mid-Atlantic and South Atlantic Planning Areas, Final Programmatic 

Environmental Impact Statement (USDOI, BOEM, 2014a).

The age distribution of the GOM sperm whale population is unknown, but they are believed 

to live at least 60 years. Potential sources of natural mortality in sperm whales include killer whales 

and a papilloma virus (Lambertsen et al., 1987). Little is known of recruitment and mortality rates; 

however, recent abundance estimates based on surveys indicate that the population appears to be 

stable, but NMFS believes that there is insufficient data to determine population trends in the GOM 

for this species at this time (Waring et al., 2016).

Cephalopods (i.e., squid, octopi, cuttlefishes, and nautilus) are the main dietary component 

of sperm whales (Davis et al., 2002). Other sperm whale populations are known to also take 

significant quantities of large demersal and mesopelagic fishes, especially the mature males in 

higher latitudes (Clarke, 1962 and 1979). Postulated feeding and hunting methods include lying 

suspended and relatively motionless near the ocean floor and ambushing prey, attracting squid and 

other prey to the white lining of their mouths by disturbing bioluminescent organisms around them to 

make their mouths more visible, or stunning prey with ultrasonic sounds (Norris and Mohl, 1983; 

Würsig et al., 2000). However, a recent study found that sperm whales produce powerful biological 

sounds in order to echolocate prey at long ranges but reduce acoustic outputs by several orders of 

magnitude when they are about their own body length from their prey (Fais et al., 2016a). This 

behaviour is inconsistent with the hypothesis that sperm whales stun their prey with ultrasonic 

sounds because the lowest outputs of sound are used in close proximity to their prey and are not at 

a magnitude that could stun their prey (Fais et al., 2016a). Evidence of ingested stones, sand, 

sponges, and other non-food items suggests they forage on or near the bottom (Rice, 1989) and 

may occasionally drown after becoming entangled in deep-sea cables that wrap around their lower 

jaw (Würsig et al., 2000).

The primary factor for the population decline was commercial whaling in the 18th, 19th, and 

20th centuries. A commercial fishery for sperm whales operated in the GOM during the late 1700’s 

to the early 1900’s, but the exact number of whales taken is not known (Townsend, 1935). The 

overharvest of sperm whales resulted in their alarming decline in the last century. The total take of 

sperm whales worldwide between 1800 and 1909 has been estimated as close to 700,000 and 

between 1910 and 1973 as close to 605,000 (Best et al., 1984). Sperm whales have been protected 

from commercial harvest by the International Whaling Commission since 1981, although the 

Japanese continued to harvest sperm whales in the North Pacific until 1988 (Reeves and 

Whitehead, 1997). Since the ban on nearly all hunting of sperm whales, there has been little 

evidence that direct effects of anthropogenic causes of mortality or injury (e.g., vessel strikes, 

commercial fishing, entanglements, etc.) are significantly affecting the recovery of sperm whale 

stocks (Perry et al., 1999), yet the effects of these activities on the behavior of sperm whales has 

just recently begun to be studied. Sperm whales are also protected by the Convention on 

International Trade in Endangered Species of Wild Flora and Fauna and the Marine Mammal
Description of the Affected Environment and Impact Analysis 4-271

Protection Act of 1972. As of 2002, the global population of sperm whales is estimated to be at 

32 percent of its pre-whaling number (Whitehead, 2002).

Since sperm whales were listed under the ESA, a concern for the impacts of anthropogenic 

activities on the physiology and behavior of marine mammals has received much attention. The 

NMFS published a final recovery plan for the sperm whale (USDOC, NMFS, 2010b), and current 

threats to sperm whale populations worldwide are discussed. Threats are defined as “any factor that 

could represent an impediment to recovery” and include fisheries interactions, anthropogenic noise, 

vessel interactions, contaminants and pollutants, disease, injury from marine debris, research, 

predation and natural mortality, direct harvest, competition for resources, loss of prey base due to 

climate change and ecosystem change, and cable laying. In the GOM, the impacts from all of these 

threats are identified as either low or unknown (USDOC, NMFS, 2010b).

The commercial fishery, which potentially could interact with the GOM sperm whale stock, is 

the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico large pelagic longline fishery (Waring et al., 

2016). There have been no reports of mortality or serious injury to sperm whales by this fishery 

(Waring et al., 2016), although one sperm whale was released alive with no serious injury after an 

entanglement interaction with the pelagic longline fishery in 2008 (Garrison et al., 2009).

In regards to the impacts of anthropogenic noise, the Five-Year Review of NMFS’ recovery 

plan recognizes that there is a concern, but additional research is needed to fully understand 

possible injury and behavior changes (USDOC, NMFS, 2015c). Anthropogenic sources from vessel 

noise, noise associated with oil production, seismic surveys, and other sources have the potential to 

impact sperm whales. Little is known about sperm whale reactions to seismic exploration, and 

available studies provide inconsistent results. Further discussion of seismic exploration and marine 

mammals can be found in the “Routine Activities” section below (Chapter 4.9.1.2).

BOEM has completed the “Sperm Whale Seismic Study in the GOM,” and a synthesis report 

was published in 2008 (Jochens et al., 2008). The principle conclusions from this multiyear research 

effort were as follows:

• the data support the conservation of sperm whales in the northern GOM as a 

discrete stock;

• sperm whales are present year-round in the GOM, with females generally having 

significant site fidelity and with males and females exhibiting significant 

differences in habitat usage;

• the sperm whale population off the Mississippi River Delta likely has a core size 

of about 140 individuals;

• GOM sperm whales seem to be smaller in individual size than sperm whales in 

some other oceans;
4-272 Gulf of Mexico Multisale EIS

• some groups of sperm whales in the GOM were mixed-sex groups of 

females/immatures and others were groups of bachelor males and typical group 

size for mixed groups was 10 individuals, which is smaller than group sizes in 

some other oceans;

• the typical diving and underwater behaviors of the GOM’s sperm whales are 

similar to those of animals in other oceans;

• the typical feeding and foraging behaviors of the GOM’s sperm whales are 

similar to those of animals in other oceans, although differences in defecation 

rates suggest possible differences in feeding success;

• in the otherwise oligotrophic Gulf of Mexico, the eddy field contributes to the 

development of regions of locally high surface productivity that, in turn, may 

create conditions favorable for the trophic cascade of surface production to the 

depths where GOM sperm whales dive to forage;

• there appeared to be no horizontal avoidance to controlled exposure of seismic 

airgun sounds by sperm whales in the main “Sperm Whale Seismic Study” area;

• data analysis suggests it is more likely than not that some decrease in foraging 

effort may occur during exposure to full-array airgun firing as compared with the 

post-exposure condition, at least for some individuals; and

• knowledge of the acoustic propagation and airgun sound characteristics is critical 

to developing the capability for accurate predictions of exposures and the 

modeling of potential resulting effects.

Recommendations from the “Sperm Whale Seismic Study” included continued conservation 

of GOM sperm whales as a separate stock, implementation of a long-term monitoring program, 

continued controlled exposure experiments, investigation into sperm whale prey fields, continued 

development of tagging sensor and instrument capabilities, and continued development of passive 

acoustic monitoring techniques.

In 2009, BOEM entered into an Interagency Agreement with NMFS’ Southeast Fisheries

Science Center for the “Sperm Whale Acoustic Prey Study.” Study objectives include quantitative 

sampling of the mid-water pelagic community within the foraging depths of sperm whales, 

examination of the relationships between acoustic backscatter and prey taxonomic composition, and 

comparison of sperm whale distribution and prey composition across habitats of the northern GOM. 

Field work is complete and sample analyses and data synthesis are ongoing.

Sirenians

The West Indian manatee typically inhabits only coastal marine, brackish, and freshwater 

areas of the southeastern U.S., the GOM, and the Caribbean Sea (Jefferson et al., 1993; O’Shea 

et al., 1995). There are two subspecies of the West Indian manatee: the Florida manatee 
Description of the Affected Environment and Impact Analysis 4-273

(T. m. latirostris), which ranges from the northern GOM to Virginia; and the Antillean manatee 

(T. m. manatus), which ranges from northern Mexico to eastern Brazil, including the islands of the 

Caribbean Sea. The Florida manatee was listed as endangered in 1967 (Federal Register, 1967) 

and is the subspecies considered for this impact analysis. On January 8, 2016, FWS proposed that 

the manatee be downlisted from endangered to threatened as a result of improvements in its 

population and habitat conditions, and reductions in threats (Federal Register, 2016d); however, this 

proposal will not affect Federal protections currently in place by the ESA.

Manatees are generalist feeders and are known to consume more than 60 species of aquatic 

vegetation in marine, estuarine, and freshwater habitats (USDOI, FWS, 2001). Manatees primarily 

use open coastal areas and estuaries, and they are also found far up in freshwater tributaries. 

Shallow grassbeds with access to deep channels are their preferred feeding areas in coastal and 

riverine habitats (near the mouths of coastal rivers), and sloughs are used for feeding, resting, 

mating, and calving (USDOI, FWS, 2001).

Florida manatees have been divided into four distinct regional management units:

• the Atlantic Coast Unit that occupies the east coast of Florida, including the 

Florida Keys and the lower St. Johns River north of Palatka, Florida;

• the Southwest Unit that occurs from Pasco County, Florida, south to Whitewater 

Bay in Monroe County, Florida;

• the Upper St. Johns River Unit that occurs in the river south of Palatka, Florida; 

and

• the Northwest Unit that occupies the Florida Panhandle south to Hernando 

County, Florida (USDOI, FWS, 2014). Manatees from the Northwest Unit are 

more likely to be seen in the northern GOM, and they can be found as far west 

as Texas; however, most sightings are in the eastern GOM (Fertl et al., 2005).

During warmer months (June to September), manatees are common along the Gulf Coast of 

Florida from the Everglades National Park northward to the Suwannee River in northwestern Florida. 

Although manatees are less common farther westward, manatee sightings increase during the 

warmer summer months. Winter habitat use is primarily influenced by water temperature as animals 

congregate at natural (springs) and/or artificial (power plant outflows) warm water sources 

(Alves-Stanley et al., 2010). The most recent count of Florida manatees is 6,063 individuals 

(2,730 individuals on the west coast of Florida and 3,333 individuals on the east coast) based on a 

February 2015 synoptic aerial survey of warm-water refuges (State of Florida, Fish and Wildlife 

Conservation Commission, 2015a). These synoptic surveys are performed each winter to get a 

count of manatees, and the most recent results may be found on the Fish and Wildlife Conservation 

Commission’s website (State of Florida, Fish and Wildlife Conservation Commission, 2016a). 

Although these surveys provide a recent count of Florida manatees, the techniques are not the best 

for accurate abundance estimates. Thus, a statewide survey was performed in 2011 and 2012 using 
4-274 Gulf of Mexico Multisale EIS

a different sampling method and produced a more accurate abundance estimate of 6,350 individuals 

for the State of Florida (Martin et al., 2015).

Per the guidance of NTL 2016-BOEM-G01, “Vessel Strike Avoidance and Injured/Dead 

Protection Species Reporting,” an operator is to report an observation of an injured or dead 

protected species, though many operators also report live animals. Recently, three live manatees 

have been spotted offshore. The first sighting was on March 20, 2013, in Green Canyon Block 653 

in 4,356 ft (1,328 m) of water; another was on March 27, 2013, next to a drillship in approximately 

6,000 ft (1,829 m) of water; and the third was on December 18, 2013, about 16 ft (5 m) off a seismic 

vessel’s port stern in 466 ft (142 m) of water. These sightings at these depths are uncommon, and 

these are the only reports of a manatee sighted by seismic observers in the GOM.

Manatees are vulnerable to various natural and anthropogenic threats. In 2013, a red-tide 

event in southwest Florida produced a brevetoxin that was ingested by manatees and that claimed a 

total of 277 individuals. This is the highest number of red-tide-related deaths in a single calendar 

year on record. State and Federal scientists are monitoring and responding to manatees affected by 

red-tide blooms along the southwest Florida coast (State of Florida, Fish and Wildlife Conservation 

Commission, 2015b). Research into the causes of death is currently ongoing and undetermined for 

the No. 58 Florida unusual mortality event (UME). A previous UME in 2011 (No. 52) was determined 

to have been caused by ecological factors (USDOC, NMFS, 2015d). While pathogens or toxins 

such as brevtoxin may cause a high number of mortalities to manatees in a relatively short 

timeframe, they are not known to occur on a regular basis.

The most common major threats to the Florida manatee are cold stress and watercraft 

collisions. When manatees experience prolonged exposure to water temperatures below 68 °F 

(20 °C), they can develop a condition called cold-stress syndrome, which can be fatal (State of 

Florida, Fish and Wildlife Conservation Commission, 2016b). Chronic cold-stress syndrome is a 

complex disease process that involves metabolic, nutritional, and immunologic factors. Some parts 

of south Florida experienced the coldest temperatures on record from January 2-13, 2010, with 

temperatures at,or below 45 oF (7.2 oC). A total of 503 manatee carcasses were verified in State 

waters from January to April 2010, which surpassed the record high annual carcass count of 429 in 

2009 (State of Florida, Fish and Wildlife Conservation Commission, 2016b).

Manatees share the waterways with watercraft and have historically sustained injuries due to 

interactions with vessels (Lightsey et al., 2006). As much as 24 percent of dead manatees 

recovered in the State of Florida between 1993 and 2003 were killed by watercraft-induced trauma, 

making it a significant contributor to Florida manatee mortality. The State of Florida’s Fish and 

Wildlife Conservation Commission analyzes manatee mortality statistics every year and have found 

similar trends with manatees and water-craft collisions (State of Florida, Fish and Wildlife 

Conservation Commission, 2015c). Yearly mortality summaries can be found on the Fish and 

Wildlife Conservation Commission’s website (State of Florida, Fish and Wildlife Conservation 

Commission, 2016c).
Description of the Affected Environment and Impact Analysis 4-275

Other Protected Marine Mammal Species

One baleen cetacean (Bryde’s whale) and 19 toothed cetaceans (including beaked whales 

and dolphins, but excluding the sperm whale since they are already discussed above) occur in the 

Gulf of Mexico. None of these species are protected under the ESA; however, all marine mammals 

are protected under the Marine Mammal Protection Act (1972).

Cetaceans—Mysticetes

The only commonly occurring baleen whale in the northern GOM is the Bryde’s whale 

(Balaenoptera edeni). The Bryde’s whale is found in tropical and subtropical waters throughout the 

world. They feed on small pelagic fishes and invertebrates (Leatherwood and Reeves, 1983; 

Cummings, 1985; Jefferson et al., 1993). Bryde’s whales in the northern GOM, with few exceptions, 

have been sighted along a narrow corridor near the 100-m (328-ft) isobath (Davis and Fargion, 

1996; Davis et al., 2000). Most sightings have been made in the De Soto Canyon region and off 

western Florida, although there have been some in the west-central portion of the northeastern 

GOM.

A recent study from NMFS’ Southeast Fisheries Science Center (Rosel and Wilcox, 2014) 

evaluated genetic diversity and phylogenetic distinctiveness of this population to determine how 

unique it is in comparison to other Bryde’s whales worldwide. The study found that the Gulf of 

Mexico Bryde’s whale population has little genetic diversity, suggesting a small population size and a 

history of isolation; and that the population is evolutionarily distinct from all other Bryde’s whales 

examined to date. The scientists conclude that the level of divergence suggests a unique 

evolutionary lineage for this population that is equivalent to currently recognized subspecies and 

species within the Bryde’s complex, and among species and subspecies of certain other baleen 

whales. The small population in the Gulf of Mexico, which is also morphologically and behaviorally

distinct from others in the complex, constitutes the only known members of this unique lineage.

The GOM population is considered a separate stock (northern GOM) for management 

purposes by NMFS (Waring et al., 2016). The status of Bryde’s whales in the northern GOM is 

unknown, as there are insufficient data to determine the population trends for this stock. On 

December 8, 2016, however, NMFS announced a 12-month finding on a petition to list the GOM 

Bryde’s whale as endangered under the Endangered Species Act (Federal Register, 2016e). If this 

listing becomes final, the Bryde’s whale would be recognized as an ESA-listed species, which would 

most likely encourage more research to aid in a recovery plan for the species. Preparation of a 

recovery plan would commence and Section 7 consultation requirements would apply.

Cetaceans—Odontocetes

Family Kogiidae: The pygmy sperm whale (Kogia breviceps) and dwarf sperm whale (Kogia 

sima) have a worldwide distribution in temperate to tropical waters (Caldwell and Caldwell, 1989). 

They feed mainly on squid but they would also eat crabs, shrimp, and smaller fishes (Würsig et al., 

2000). In the GOM, they occur primarily along the continental shelf edge and in deeper waters off 
4-276 Gulf of Mexico Multisale EIS

the continental shelf (Mullin et al., 1991). At sea, it is difficult to differentiate dwarf sperm whales 

from pygmy sperm whales, and sightings are often grouped together as “Kogia spp.” Very little is 

known about the species except from studies on stranded individuals.

Family Ziphiidae (Beaked Whales): Beaked whales in the GOM are identified either as 

Cuvier’s beaked whales or are grouped into an undifferentiated complex (Mesoplodon spp.) because 

of their similarity in appearance and potential identification errors. In the northern GOM, they are 

broadly distributed in waters >3,281 ft (1,000 m) over lower slope and abyssal landscapes (Davis 

et al., 1998 and 2000). Beaked whales were seen in the GOM in all seasons during GulfCet aerial 

surveys (Mullin and Hoggard, 2000). Beaked whale species that may occur within the GOM are 

usually observed singly or in small groups of individuals (Jefferson et al., 2008). As a group they are 

poorly known but are thought to be deep-diving animals. They feed at depth on deepwater

cephalopods and fishes (Mead, 2002).

Three species of Mesoplodon are known to occur in the GOM based on sighting and 

stranding data and are considered provisional stocks (Wursig et al., 2000; Waring et al., 2014). The 

Gervais’ beaked whale (Mesoplodon europaeus) appears to be widely but sparsely distributed 

worldwide in temperate to tropical waters (Leatherwood and Reeves, 1983). Stranding records 

suggest that this is probably the most common mesoplodont in the northern GOM (Jefferson and 

Schiro, 1997). The Blainville’s beaked whale (Mesoplodon densirostris) is distributed throughout 

temperate and tropical waters worldwide, but it is not considered common (Würsig et al., 2000). 

Cuvier’s beaked whale (Ziphius cavirorostris) is widely (but sparsely) distributed throughout 

temperate and tropical waters worldwide (Würsig et al., 2000). They are sighted in the GOM in all 

seasons in water depths typically >1,640 ft (500 m) (Maze-Foley and Mullin, 2006). Sightings data 

indicate that Cuvier’s beaked whale is probably the most common beaked whale in the GOM 

(Jefferson and Schiro, 1997; Davis et al., 1998 and 2000).

Family Delphinidae (Dolphins): Fourteen members of the dolphin family are known to occur 

in the GOM. Dolphins are often gregarious and commonly form aggregations that can range from a 

few to several thousand individuals depending on the species (Jefferson et al., 2008; Würsig et al., 

2000).

Of the 14 members, the bottlenose dolphin (Tursiops truncatus) is the most common 

inhabitant of the continental shelf and upper slope waters of the northern GOM. Bottlenose dolphins 

are opportunistic feeders, taking a wide variety of fishes, cephalopods, and shrimp (Davis and 

Fargion, 1996; Jefferson and Schiro, 1997; Wells and Scott, 1999). There appears to be two 

ecotypes of bottlenose dolphins, a coastal form (52-210 ft;16-67 m) and an offshore form (about 

820 ft; 250 m) (Hersh and Duffield, 1990; Mead and Potter, 1990; Baumgartner, 1995). The coastal 

or inshore stocks are genetically isolated from the offshore stock (Curry and Smith, 1997). Inshore 

stocks are further provisionally delineated into 31 bay, sound, and estuarine stocks (Waring et al., 

2016).
Description of the Affected Environment and Impact Analysis 4-277

Species endemic to tropical and subtropical waters of the Atlantic Ocean include the 

Clymene dolphin (Stenella clymene) (Perrin and Mead, 1994) and pantropical spotted dolphin 

(Stenella attenuata) (Perrin and Hohn, 1994). The Clymene dolphin is thought to feed on fishes and 

cephalopods (Leatherwood and Reeves, 1983; Jefferson et al., 1993; Mullin et al., 1994b). 

Sightings in the GOM are relatively common and suggest a primary range offshore of the 100-m 

(328-ft) isobath (Davis et al., 2000; Würsig et al., 2000). The pantropical spotted dolphin feeds on 

epipelagic fishes and cephalopods (Leatherwood and Reeves, 1983; Jefferson et al., 1993). It is the 

most common cetacean in the oceanic northern GOM (Mullin et al., 1994a) and is found in the 

deeper waters off the continental shelf between the 100-m and 2,000-m (328- and 6,565-ft) depth 

contours (Mullin et al., 1994a; Davis et al., 1998 and 2000; Würsig et al., 2000).

The Atlantic spotted dolphin (Stenella frontalis), Risso’s dolphin (Grampus griseus), roughtoothed dolphin (Steno bredanensis), spinner dolphin (Stenella longirostris), striped dolphin (Stenella 

coeruleoalba), and the false killer whale (Pseudorca crassidens) are found in tropical to temperate 

waters (Jefferson and Schiro, 1997; Leatherwood and Reeves, 1983; Miyazaki and Perrin, 1994; 

Perrin and Gilpatrick, 1994; Perrin et al., 1994a and 1994b). Another species, the Fraser’s dolphin 

(Lagenodelphis hosei), has a worldwide distribution in tropical waters (Perrin et al., 1994c). These 

dolphin species are known to feed on a wide variety of fishes, cephalopods, crustaceans, and 

benthic invertebrates (Leatherwood and Reeves, 1983; Jefferson et al., 1993; Jefferson and Schiro, 

1997; Perrin et al., 1994a). In the GOM, they occur primarily along the continental shelf and 

continental slope (Mullin and Fulling, 2004). The rough-toothed dolphin, striped dolphin, spinner 

dolphin, and false killer whale can occur in deeper waters off the continental shelf (Davis and 

Fargion, 1996, Mullin and Fulling, 2004).

The killer whale (Orcinus orca) has a worldwide distribution from tropical to polar waters 

(Dahlheim and Heyning, 1999). They feed on marine mammals, marine birds, sea turtles, 

cartilaginous and bony fishes, and cephalopods (Leatherwood and Reeves, 1983; Jefferson et al., 

1993). In the GOM, they occur primarily in the deeper waters off the continental shelf (Davis and 

Fargion, 1996).

The melon-headed whale (Peponocephala electra) and pygmy killer whale (Feresa 

attenuata) have worldwide distributions in subtropical to tropical waters (Jefferson et al., 1992; Ross 

and Leatherwood, 1994), feeding on cephalopods and fishes (Mullin et al., 1994a; Jefferson and 

Schiro, 1997). In the GOM, they occur in the deeper waters off the continental shelf (Mullin et al., 

1994a).

The short-finned pilot whale (Globicephala macrorhynchus) is distributed worldwide in 

tropical to temperate waters (Leatherwood and Reeves, 1983). They feed predominantly on squid, 

with fishes being consumed occasionally (Würsig et al., 2000). Aggregations of short-finned pilot 

whales are commonly associated with other cetacean species (Jefferson et al., 2008). In the GOM, 

they are most frequently sighted along the continental shelf and continental slope.
4-278 Gulf of Mexico Multisale EIS

Factors Influencing Cetacean Distribution and Abundance

The distribution and abundance of cetaceans within the northern GOM is strongly influenced 

by various mesoscale oceanographic circulation patterns. These patterns are primarily driven by 

river discharge (primarily the Mississippi River), wind stress, and the Loop Current and its derived 

circulation phenomena. Approximately once or twice a year, the Loop Current sheds anticyclonic 

eddies (also called warm-core rings), which, in turn, spawn cyclonic eddies (also called cold-core 

rings) during interaction with one another and upon contact with topographic features of the 

continental slope and shelf edge. These cyclonic eddies contain and maintain high concentrations 

of nutrients and stimulate localized production of phytoplankton (Davis et al., 2000), which, in turn, 

provides various food resources for various predators. The Loop Current and its associated eddies 

can occur throughout the GOM region, including south of the U.S. Exclusive Economic Zone limits, 

but this area is very poorly studied with little to no information on cetacean distributions. River 

outflow also may be entrained within the confluence of a cyclone-anticyclone eddy pair and 

transported beyond the continental slope. Marine mammals may focus their foraging efforts on 

these abundant prey locations to improve overall efficiency and reduce energy costs (Bailey and 

Thompson, 2010). Other than factors influencing feeding behaviors, very little is known about other 

factors that may influence marine mammal distribution in the northern GOM because there are few 

studies that examine them.

Critical Habitat

Critical habitat is designated if specific areas of habitat occupied by a species listed as 

endangered or threatened under the ESA may contain physical or biological features essential to the 

species’ conservation, and may require special management considerations or protection. The only 

marine mammal that has critical habitat currently listed within the GOM is the West Indian manatee; 

this is illustrated in Figure 4-25 (50 CFR § 17.95).

4.9.1.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from activities described in Chapter 3

and the potential impacts that could result from a single lease sale. As mentioned earlier in 

Chapter 4.9, BOEM has considered the potential effects of impact-producing factors that are 

reasonably foreseeable to occur based on credible scientific research and past data for the following 

analysis. This analysis applies to all alternatives analyzed in Chapter 4. While a proposed WPA 

lease sale (Alternative C) would be in a smaller area with less projected activity than a regionwide 

(Alternative A) or CPA/EPA lease sale (Alternative B), as described in Chapter 3, marine mammal

species are widely distributed throughout the planning areas. As such, activities isolated to specific 

planning areas pose similar potential impacts to populations as do activities occurring in all planning 

areas. For example, if a marine mammal species were to be accidentally struck by an OCS vessel, 

it would have the same impact to that individual and its respective population estimate in the WPA 

as it would in the CPA or EPA. Although it can be speculated that a smaller leased area resulting in 

less projected OCS oil- and gas-related activity would decrease the likelihood of OCS oil- and gas-
Description of the Affected Environment and Impact Analysis 4-279

related activities impacting marine mammal populations, there are not enough conclusive data on 

the density and distribution of marine mammal populations in the GOM throughout the year to 

conclude that speculation. Therefore, because of the diversity and wide distribution of species in the 

Area of Interest, the level of impacts would be the same for Alternatives A, B, C, and D. Under 

Alternative E, there would be no new activities associated with a proposed lease sale; however, 

activities associated with past lease sales and non-OCS oil- and gas-related activities would 

continue. Following this discussion of environmental consequences, there is a more detailed 

summary of the potential impacts as they relate to the action alternatives.

As mentioned earlier in Chapter 4.9.1.1, the PBR of a marine mammal species plays an 

important role in marine mammal management due to the fact that the same impact-producing factor 

may have a more serious impact on a marine mammal stock that has a lower PBR and a less 

serious impact to a marine mammal stock with a higher PBR. In other words, if an impact-producing 

factor were to negatively affect a number of individuals of a marine mammal stock that exceeds its 

respective PBR estimate, it could possibly diminish the continued viability of the stock, including the 

annual rates of recruitment or survival. BOEM understands that the PBR is a very conservative 

estimate and that the abundance estimates used in estimating the PBR may not accurately reflect 

the actual abundances of marine mammal stocks. The following evaluation considers how the 

impact-producing factors from routine activities, reasonably foreseeable accidental events, and 

cumulative impacts from activities described in Chapter 3 may potentially impact a marine mammal 

species based on its respective PBR (refer to Table 4-19 for list of marine mammal species and their 

respective PBR). BOEM has made conscientious efforts to comply with the spirit and intent of NEPA

and to be comprehensive in its analyses of potential environmental impacts to marine mammals, 

including species that are poorly studied.

4.9.1.2.1 Routine Activities

Potential impacts on marine mammal species may occur from routine activities associated 

with a proposed lease sale. As a result of OCS oil- and gas-related routine activities in the GOM, 

the major impact-producing factors affecting marine mammals include geological and geophysical 

activities, transportation, operational discharges, decommissioning, and noise. 

Geological and Geophysical Activities

Geophysical (seismic) exploration is an integral part of oil and gas discovery, development, 

and production in the GOM (refer to Chapter 3.1.2.1). With technical advances that now allow 

extraction of petroleum from the ultra-deep areas of the Gulf, seismic surveys are routinely 

conducted in virtually all water depths of the GOM, including the deep habitat of the endangered 

sperm whale. As discussed in Chapter 3.1.9, acoustic sources are described by their sound 

characteristics and are generally divided into impulsive noise and nonimpulsive noise for the 

regulatory process. Underwater noise sources from G&G activities include impulsive sound sources 

such as airguns, boomers, subbottom profilers, multibeam echosounders, and side-scan sonars, as 

well as continuous sources such as vessel and aircraft noise. Overall, the potential for noise 

impacts from these sound sources on marine mammals is highly variable and depends on the 
4-280 Gulf of Mexico Multisale EIS

specific circumstances of a given situation. Furthermore, the same sound source can propagate 

differently depending on the physical environment. How a sound from a specific source propagates 

through a particular environment depends on a variety of factors, including physical environmental 

factors (e.g., salinity, temperature, bathymetry, seafloor type, and tow depth), sound characteristics 

associated with different sources (e.g., source level, directionality, source type, and duration for both 

impulsive or continuous signals), frequency (i.e., higher frequencies dissipate faster and lower 

frequencies may travel farther depending on water depth), and intensity (i.e., decibel level).

With the growing number of studies assessing the potential impacts of sound on marine 

mammal species, NMFS recently announced the availability of the Technical Guidance for 

Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing—Underwater Acoustic 

Thresholds for Onset of Permanent and Temporary Threshold Shifts, which provides updated 

acoustic thresholds, above which individual marine mammals are predicted to experience changes 

in their hearing sensitivity (either temporary or permanent) for all underwater anthropogenic sound 

sources (USDOC, NMFS, 2016a).

The impacts of noise from G&G activities could include one or more of the following: 

masking of natural sounds, which could reduce an individual’s ability to effectively communicate, 

detect predators or prey, and detect important environmental features (Clark et al., 2009); behavioral 

disturbance (e.g., changes in feeding or mating behaviors); tolerance; and temporary or permanent 

hearing impairment, or nonauditory physical or physiological impacts (Richardson et al., 1995; 

Nowacek et al., 2007; Southall et al., 2007). Given that mysticetes produce calls that span a lowfrequency range (20 Hertz-30 kilohertz) with their best hearing abilities presumably falling into this 

range as well, they would be most likely to experience impacts from the low-frequency sounds 

produced by seismic surveys (Richardson et al., 1995). In contrast, odontocetes produce calls and 

hear best at mid to high frequencies (Richardson et al., 1995) and appear less vulnerable to lowfrequency sound sources than mysticetes. Permanent hearing impairment would constitute injury; 

however, temporary threshold shift is not considered an injury (Southall et al., 2007). More detailed 

information on the seismic surveying technology and techniques that could be used is provided in

BOEM’s Atlantic OCS Proposed Geological and Geophysical Activities: Mid-Atlantic and South 

Atlantic Planning Areas—Final Programmatic Environmental Impact Statement. BOEM’s Atlantic 

G&G Activities Programmatic EIS also includes appendices on marine mammal hearing and 

sensitivity to acoustic impacts which, although emphasizes species specific to the Atlantic OCS, a 

majority of the species found in the GOM were included in the analysis and would be expected to 

respond in a similar manner to G&G activities in the GOM (USDOI, BOEM, 2014a). As of this 

Multisale EIS, BOEM, with BSEE and NMFS as cooperating agencies, prepared the Gulf of Mexico 

OCS Proposed Geological and Geophysical Activities: Western, Central, and Eastern Planning 

Areas; Draft Programmatic Environmental Impact Statement (Gulf of Mexico G&G Programmatic 

EIS) to evaluate the potential environmental impacts of multiple G&G activities within Federal waters 

of the Gulf of Mexico’s OCS and adjacent State waters, and is currently in the process of evaluating 

public comments. This Gulf of Mexico G&G Programmatic EIS evaluates all G&G activities in the 

GOM (for oil and gas, marine minerals, and renewable activities) over a 10-year period, including a 
Description of the Affected Environment and Impact Analysis 4-281

small subset of reasonably foreseeable postlease G&G activities that may occur as a result of a 

proposed lease sale being evaluated in this Multisale EIS.

As mentioned in Chapter 4.9.1.1, Description of the Affected Environment, the only regularly 

occurring mysticete in the GOM is the Bryde’s whale, which is currently proposed to be listed as 

endangered under the ESA in the GOM (Federal Register, 2016e). Based on this proposal’s 

comprehensive status review and after considering the Status Review Team’s threats assessment, 

NMFS concluded that energy exploration and development is one of many contributing factors 

adding to the GOM Bryde’s whale’s risk of extinction. However, both NMFS and the Status Review 

Team stated that this conclusion took into account the possibility that the EPA, which is currently 

under moratorium, would become available for energy exploration in the year 2022 (Rosel et al., 

2016) and that the potential oil- and gas-related activities would commence there. This area 

encompasses the Bryde’s whale current primary habitat in the GOM. Currently, there are few 

seismic surveys occurring in the EPA, and it is expected that nearby noise from seismic surveys 

occurring in the CPA are limited in impacts to the Bryde’s whale primary habitat (Rosel et al., 2016). 

As this Multisale EIS only relates to lease sales through 2022, during the period that much of the 

EPA remains under Congressional moratorium, any postlease activities related to a proposed action 

in the Bryde’s whale habitat in the EPA would likely be related to transporation. No postlease G&G 

activities as a result of a proposed lease sale evaluated in this Multisale EIS would occur in the area 

of the EPA under moratorium.

Another impact-producing factor to marine mammals that is associated with G&G activities is 

the potential for gear interaction. Marine mammals and other various marine life can become 

entangled in some types of lines associated with G&G activities; this has occurred in the past with 

ocean bottom cable/ocean bottom node surveys and other activities where rope tethers were used 

(e.g., anchors and buoys). The deployment of nodes and cables is accomplished by a remotely 

operated vehicle, by dropping nodes on a tether, or by laying cables off the back of a layout boat. 

The G&G permit applications are reviewed by BOEM and NMFS to set conditions of approval with 

each activity that would minimize impacts caused by gear interactions which are expected to be rare.

The NTL 2016-BOEM-G02, “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program,” provides guidance to protect marine mammals and sea 

turtles during seismic operations. This NTL clarifies how operators should implement seismic survey 

mitigating measures, including ramp-up procedures, the use of a minimum sound source, airgun 

testing, shutdowns, and protected species observation and reporting. The Protected Species 

Stipulation, if applied, would make compliance with the guidance identified in the NTL mandatory for 

lessee activities. In addition, NMFS, BOEM, and BSEE collaborated to publish the technical 

memorandum “National Standards for a Protected Species Observer Program” in order to provide 

guidance on how to reduce impacts to protected species from G&G activities by standardizing the 

variation in and improving the management of the program (Baker et al., 2013).

Without implementation of BOEM’s mitigations, marine mammals would be vulnerable to 

impacts from the noise produced from airguns, vessel strikes, and entanglement from gear 
4-282 Gulf of Mexico Multisale EIS

interaction. The impacts from these factors with mitigations mentioned above would be expected to 

be negligible to moderate when considering that the increasing number of studies analyzing the 

effects of G&G activities on marine mammals have found no evidence of mortality and variable 

results in behavioral changes and possible hearing impairment as a result of exposure to these 

activities. An example of a moderate impact would be if an individual oceanic bottlenose dolphin 

(PBR 42 individuals) would become entangled from gear interaction, resulting in physical injury or 

mortality that would have a localized impact on that individual, but it would not diminish the 

continued viability of the population. However, with the use of ramp-up procedures, minimum sound 

sources, airgun testing, and protected species observation and reporting, and limited seismic 

surveys in the EPA, it is reasonably foreseeable that most marine mammals would be detected and 

that proper procedures, including shutdowns, would be used to avoid any impacts, making them 

negligible. 

Transportation

The oil and gas industry uses a variety of vessels running from shore bases to offshore OCS 

oil and gas structures (refer to Chapter 3.1.4.3). Increased traffic from service and support vessels 

would increase the probability of collisions between vessels and marine mammals. These collisions 

can cause major injuries and/or fatalities (e.g., the sperm whale [Waring et al., 2013] and bottlenose 

dolphin [Fertl, 1994]). Slow-moving cetaceans or those that spend extended periods of time at the 

surface might be expected to be the most vulnerable (Vanderlaan and Taggert, 2007). Smaller 

delphinids often approach vessels that are in transit to bow-ride; however, vessel strikes are less 

common for these faster moving mammals or are underreported (Wells and Scott, 1997). Nowacek 

and Wells (2001) found that bottlenose dolphins had longer interbreath intervals during boat 

approaches compared with control periods (no boats present within 100 m [328 ft]) in a study 

conducted in Sarasota Bay, Florida. They also found that dolphins’ decreased interanimal distance, 

changed heading, and increased swimming speed significantly more often in response to an 

approaching vessel than during control periods. Behavioral changes such as these could stress and 

disorient individuals, which could then result in an accidental vessel collision.

Collisions of vessels with marine mammals are not uncommon (Laist et al., 2001). 

Vanderlaan and Taggert (2007) examined the literature for large whale species and reported that the 

probability for vessel strikes is largely a function of vessel speed. Data compiled by Laist et al. 

(2001) indicate that relatively large (>80 m; 262 ft) and fast-moving vessels (>14 kn; 16 mph) are 

most commonly involved in collisions with marine mammals. They also conclude that the majority of 

collisions appear to occur over or near the continental shelf and that the whales usually are not seen 

beforehand or are seen too late to be avoided. The rapid increase in exploration and development 

of petroleum resources in deep oceanic waters of the northern Gulf has increased the risk of OCS 

vessel collisions with sperm whales and other deep-diving cetaceans (e.g., Kogia and beaked 

whales). Deep-diving whales may be more vulnerable to vessel strikes because of the extended 

surface period required to recover from extended deep dives (Fais et al., 2016b). Sperm whales 

have been shown to be unable to outmaneuver a fast vessel approaching under stratified water 

conditions (Gannier and Marty, 2015). Although the sperm whale is the most likely large whale to be 
Description of the Affected Environment and Impact Analysis 4-283

struck by a vessel in the GOM, there is only evidence of one mortality due to a vessel strike in 1990, 

as documented as of 2013 (Waring et al., 2016). The whale was found with a cut in the vicinity of 

Grand Isle, Louisiana, so the origin of the vessel that possibly struck it is unknown. Since the 

implementation of the vessel strike NTL, there have been no reports of any vessel strikes on marine 

mammals.

Florida manatees are commonly found in shallow coastal waters of Florida, but they have 

been found along the entire northern GOM from Florida to Texas (Fertl et al., 2005), though some 

recent deepwater sightings have occurred. Vessel strikes are the most common cause of humaninduced mortality for manatees (State of Florida, Fish and Wildlife Conservation Commission, 

2015c), and most manatees bear prop scars from contact with vessels. The vast majority of strikes 

result from recreational and fishing vessels, not those related to oil and gas activities. Service and 

support vessels traveling through coastal areas to and from oil and gas structures have the rare 

potential to impact manatees by vessel collisions. In 1995, for example, an oil crew workboat struck 

and killed a manatee in a canal near coastal Louisiana (Fertl et al., 2005). Inadequate hearing 

sensitivity at low frequencies (Gerstein et al., 1999), slow movement, and use of shallow and surface 

waters are contributing factors to their vulnerability to vessel strike impacts. While manatees are 

less common in the western Gulf, they are being seen more frequently, and increased sightings 

indicate that there is a potential for risks to this species from OCS vessel traffic. There is the 

possibility of short-term disruption of movement patterns and/or behavior caused by vessel noise

and disturbance; however, these are not expected to impact survival and growth of manatees in the 

GOM.

Expected industry service trip numbers as a result of Alternative A, B, C, or D are described 

in Chapter 3.1.4.3 (Table 3-2). BOEM issued NTL 2016-BOEM-G01, “Vessel Strike Avoidance and 

Injured/Dead Protected Species Reporting,” which explains how operators must implement 

measures to minimize the risk of vessel strikes to protected species and to report observations of 

injured or dead protected species. The Protected Species Stipulation, if applied, would make 

compliance with the guidance identified in the NTL mandatory for lessee activities. Adherence to the 

NTL protocols is expected to reduce but not eliminate the risk of potential vessel strikes with marine 

mammals. 

Without implementation of mitigations, marine mammals would be vulnerable to direct 

impacts from OCS oil- and gas-related vessel strikes. The impacts from these factors with 

mitigations are expected to be negligible to minor when considering the high probability of 

detecting a marine mammal while in transit. An example of a minor impact would be if a group of 

20 rough-toothed dolphins (PBR 3 individuals) were to change their course to avoid an OCS vessel. 

However, with the use of vessel strike avoidance guidelines, it is reasonably foreseeable that marine 

mammals would be detected and that proper procedures, including reduced speed, change in 

course, or shutdown, would be used to avoid impacts to marine mammals, which would be 

negligible.
4-284 Gulf of Mexico Multisale EIS

Discharges and Wastes

The primary operational waste discharges generated during offshore oil and gas exploration 

and development are drilling fluids, drill cuttings, produced water, deck drainage, sanitary wastes, 

and domestic wastes (refer to Chapter 3.1.5). During production activities, additional waste streams 

include well treatment, workover, and completion fluids. Minor additional discharges occur from 

numerous sources; these discharges may include desalination unit discharges, blowout preventer

fluids, boiler blowdown discharges, excess cement slurry, and uncontaminated freshwater and 

saltwater. Discharges are regulated by the USEPA through the issuance of NPDES permits. 

Pollutants discharged into navigable waters of the U.S. are regulated by the USEPA under the Clean 

Water Act of 1972 and subsequent provisions (33 U.S.C. §§ 1251 et seq.). Specifically, an NPDES 

permit must be obtained from the USEPA under Sections 301(h) and 403 (Federal Register, 1980) 

of the Clean Water Act (refer to Chapter 4.2, Water Quality).

Heavy metal accumulations in marine mammal tissues are of concern worldwide (Bossart, 

2006). Trace metals, including mercury, in drilling discharges have been a particular concern. 

However, Neff et al. (1989) concluded that metals associated with drilling fluid were virtually 

nonbioavailable to marine organisms. Marine mammals generally are inefficient assimilators of 

petroleum compounds in prey (Neff, 1990). Analyses of samples from live GOM and Atlantic 

bottlenose dolphins showed high levels of polyfluoroalkyl compounds (Houde et al., 2005). Recent 

work by Kucklick et al. (2011) in the GOM identified a number of persistent organic pollutants in 

bottlenose dolphins, and Fair et al. (2010) documented unusually high levels of organic chemicals in 

bottlenose dolphins in Atlantic populations. Adequate baseline data are not available to determine 

the significant sources of contaminants that accumulate in GOM cetaceans or their prey, due in no 

small part to the fact that contaminants are introduced into the GOM from a variety of national 

watersheds. Many cetaceans are wide-ranging animals, which also compounds the issue. Coastal 

cetacean species tend to have higher levels of metals than those frequenting oceanic waters 

(Johnston et al., 1996). Oceanic cetaceans feeding on cephalopods have higher levels of cadmium 

in their tissues than comparable fish-eating species (Johnston et al., 1996). There also is, in many 

cases, a striking difference between the relatively high mercury levels in the toothed whales and the 

lower levels found in baleen whales, which is probably attributable to the different prey species 

consumed by baleen whales, as well as differences in the habitat (Johnston et al., 1996).

Most operational discharges are diluted and dispersed when released in offshore areas, and 

they are not expected to directly affect any marine mammal species (Kennicutt, 1995). Any potential 

impacts from drilling fluids would be indirect, either as a result of impacts to prey species or possibly 

through ingestion via the food chain (Neff et al., 1989). Contaminants in drilling muds or waste 

discharge may biomagnify and bioaccumulate in the food web, which may kill or debilitate important 

prey species of marine mammals or species lower in the marine food web. Releases of toxic 

discharges are regulated by the USEPA through the issuance of NPDES permits to keep 

contaminants below harmful levels. These regulations and permit provisions are designed to 

prevent unreasonable degradation of the marine environment, and adherence to these requirements 

by industry would be expected to result in limited impacts to water quality, and therefore, indirect 
Description of the Affected Environment and Impact Analysis 4-285

impacts to marine mammals would likewise be small. Without implementation of requirements, 

marine mammals would be vulnerable to direct and indirect impacts from operational discharges. 

The impacts from these factors are, therefore, expected to be negligible given assumed compliance 

with existing regulations and permit requirements.

Decommissioning

The use of explosives is one of industry’s preferred methods for the severance of structures 

from their foundations in the GOM (refer to Chapter 3.1.6). It has been demonstrated that nearby 

underwater blasts can injure or kill marine mammals (Richardson et al., 1995). Injuries from highvelocity underwater explosions result from two factors: (1) the very rapid rise time of the shock 

wave; and (2) the negative pressure wave generated by the collapsing bubble, which is followed by 

a series of decreasing positive and negative pressure pulses (USDOI, MMS, 2004b). The extent of 

injury largely depends on the intensity of the shock wave and the size and depth of the animal at the 

time of the detonation (Yelverton et al., 1973).

BOEM (then BOEMRE) issued “Decommissioning Guidance for Wells and Platforms” (NTL 

2010- BSEE-G05) to offshore operators; it provides clarification and interpretation of regulations 

regarding decommissioning, as well as guidance to operators proposing to use explosives to 

perform well/casing severance. These guidelines specify and reference mitigation, monitoring, and 

reporting requirements. As noted in Chapter 3.1.6, decommissioning for wells and platforms are 

site specific and are reviewed by BSEE and BOEM.

Expected numbers of production structures to be removed using explosives as a result of 

Alternative A, B, C, or D are reported in Chapter 3.1.6. Explosive severance could moderately 

impact marine mammals; however, with implementation of the Bureau of Safety and Environmental 

Enforcement’s NTL guidelines and regulations, and NMFS’s Observer Program for explosive 

removal, impacts to marine mammals from explosive severance are expected to be negligible to 

moderate. Although the NTL’s guidelines and regulations, along with NMFS’ Observer program for 

explosive removal, would greatly reduce impacts of decommissioning activities to marine mammals, 

they may not be completely eliminated. To date, there are no documented “takes” of marine 

mammals resulting from explosive removals of offshore structures. Decommissioning activities and 

their potential impacts to different marine mammal species are described further in the StructureRemoval Operations on the Gulf of Mexico Outer Continental Shelf: Programmatic Environmental 

Assessment (USDOI, MMS, 2005), as well as in Chapter 3. In addition, a site-specific NEPA

analysis, in the form of an EA or EIS, is completed for all structure removals that propose explosive 

severance methods and/or site-clearance trawling. Without implementation of mitigations, marine 

mammals would be vulnerable to direct impacts from explosive charges used for the removal of 

production structures. The impacts from these factors with mitigations are expected to be negligible

to minor when considering that there have been no “takes” of marine mammals due to 

decommissioning activities. An example of a minor impact would be if a group of 10-15 pantropical 

spotted dolphins (PBR 407 individuals) were outside of the impact zone prior to a detonation and 

swam away after the explosives were detonated. It would have a localized behavioral impact on that 
4-286 Gulf of Mexico Multisale EIS

group of individuals, but it would not diminish the continued viability of the population. However, with 

the use of decommissioning guidelines, as well as the fact that there have been no documented 

“takes” of marine mammals from explosive removal activities, it is reasonably foreseeable that 

decommissioning activities would have a negligible impact.

Noise

As discussed in Chapter 3.1.9, acoustic sources are described by their sound characteristics 

and are generally divided into impulsive noise and nonimpulsive noise for the regulatory proceess. 

Impulsive noises (e.g., impact pile drivers) are generally considered powerful sounds with relatively 

short durations, broadband frequency content, and rapid rise times to peak levels. Nonimpulsive 

noise generally includes all other noise (e.g., sonars and vibratory pile drivers) and includes 

continuous anthropogenic noise (e.g., vessel noise). Overall, the potential for noise impacts from 

these sound sources on marine mammals is highly variable and depends on the specific 

circumstances of a given situation.

Aircraft overflights (either helicopter or fixed-wing) in close proximity to marine mammals

may elicit a startle response due to either the increasing noise as the aircraft approaches or due to 

the physical presence of the aircraft in the air. Refer to Chapter 3.1.9 for more information on OCS 

oil- and gas-related noise. With more than 1 million helicopter take offs/landings expected per year 

from activity related to past, proposed, and future lease sales, the OCS industry’s activity contributes 

greatly to this noise source. Although air traffic offshore is limited, the military maintains 11 military 

warning areas and 6 water test areas in the GOM (Error! Reference source not found.). Some 

commercial fisheries include aerial surveillance. Scientific research aerial surveys are occasionally 

scheduled over the GOM. Commercial and private aircraft also traverse the area.

Marine mammals often react to aircraft overflights by hasty dives, turns, or other abrupt 

changes in behavior. Responsiveness varies widely depending on factors such as species, the 

activity the animals are engaged in, and water depth (Richardson et al., 1995). Marine mammals 

engaged in feeding or social behavior are often insensitive to overflights, while those in confined 

waters or those with calves may be more responsive. The impacts appear to be transient, and there 

is no indication that long-term displacement of marine mammals occurs. However, the absence of 

conspicuous response does not show that the animals are unaffected; it is not known whether these 

subtle impacts are biologically significant (Richardson and Würsig, 1997).

Aircraft noise is generally short in duration and transient in nature, although it may ensonify 

large areas. Much of the noise from a passing aircraft is reflected and does not penetrate the water 

(Urick, 1972). Helicopter noises contain dominant tones (resulting from rotors) generally below 

500 Hz (Richardson et al., 1995). The Federal Aviation Administration’s Advisory Circular 91-36D 

(2004) encourages pilots to maintain an altitude of higher than 610 m (2,000 ft) over noise-sensitive 

areas. Corporate helicopter policy states that helicopters should maintain a minimum altitude of 

231 m (700 ft) while in transit offshore and 152 m (500 ft) while working between platforms. It is 

unlikely that marine mammals would be affected by routine OCS helicopter traffic operating at these 
Description of the Affected Environment and Impact Analysis 4-287

altitudes. Routine overflights may elicit a startle response from and interrupt marine mammals 

nearby (depending on the activity of the animals), possibly causing temporary displacement from 

feeding, mating, or traveling activities. This temporary disturbance to marine mammals may occur 

as helicopters approach or depart OCS oil- and gas-related facilities if animals are near the facility. 

Without implementation of guidelines and regulations by NMFS under the authority of the MMPA, 

marine mammals would be vulnerable to direct impacts from routine overflights. The impacts from 

these factors with these guidelines and mitigations are expected to be negligible. 

The dominant source of human noise in the sea is ship noise (Tyack, 2008). The primary 

sources of vessel noise are propeller cavitation, propeller singing, and propulsion; other sources 

include auxiliaries, flow noise from water dragging along the hull, and bubbles breaking in the wake 

(Richardson et al., 1995). The intensity of noise from service vessels is roughly related to ship size 

and speed. Large ships tend to be noisier than small ones, and ships underway with a full load (or 

towing or pushing a load) produce more noise than unladed vessels. For a given vessel, relative 

noise also tends to increase with increased speed. The ambient noise environment in the GOM is 

filled with ship “noise” associated with oil- and gas-related activities, shipping, and recreational 

vessels, raising concerns that elevated levels of noise may interfere with the behavior and 

physiology of marine mammals (Tyack, 2008). Many of the industry-related noises are believed to 

be out of, or on the limits of, marine mammal hearing, and the sounds are also generally temporary. 

Impacts from vessel noise could disturb animals in the immediate vicinity of the vessel; however, the 

noise would be transitory in nature. Further detailed information on marine mammal hearing and 

sensitivity to acoustic impacts may be found in BOEM’s Atlantic OCS Proposed Geological and 

Geophysical Activities: Mid-Atlantic and South Atlantic Planning Areas, Final Programmatic 

Environmental Impact Statement, which can be found on BOEM’s website (USDOI, BOEM, 2014a).

The aforementioned Gulf of Mexico G&G Programmatic EIS, for which is currently in the process of 

evaluating public comments, also includes more detailed information on marine mammal hearing 

and sensitivity to acoustic impacts within the Federal waters of the Gulf of Mexico’s OCS and 

adjacent State waters. 

Andrew et al. (2002) reported that, over a 33-year period, increases in shipping noise levels 

in the ocean may account for a 10-decibel (dB) increase in ambient noise between 20 and 80 Hz 

and between 200 and 300 Hz, and a 3-dB increase in noise at 100 Hz on the continental slope of 

Point Sur, California. Although comparable baseline data are not available for the GOM, it is likely 

that similar ambient noise increases have occurred. Much of the change is expected to be 

attributable to commercial shipping (greater numbers of ships in the GOM and larger ship size are 

both factors). However, the expansion of oil and gas industry activities, including more structures, 

more exploration (seismic surveys) and drilling, a larger service boat fleet, and much greater 

distances to travel to deepwater installations, has also contributed to more noise in GOM waters.

The continued presence of various cetacean species in areas with heavy vessel traffic 

suggests a considerable degree of tolerance to vessel noise and disturbance. Evidence suggests, 

however, that some whale species have reduced their use of certain areas heavily utilized by ships 

(Richardson et al., 1995), possibly avoiding or abandoning important feeding areas, breeding areas, 
4-288 Gulf of Mexico Multisale EIS

resting areas, or migratory routes. Vessel noise could interfere with marine mammal communication 

either by masking important sounds from conspecifics, masking sounds from predators, or by forcing 

animals to alter their vocalizations (Tyack, 2008). There is the possibility of short-term disruption of 

movement patterns and/or behavior caused by vessel noise and disturbance; however, these are not 

expected to impact survival and growth of any marine mammal populations in the GOM. BOEM 

issued NTL 2016-BOEM-G01, “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting,” explains how operators must implement measures to minimize the risk of vessel strikes 

to protected species and report observations of injured or dead protected species. This guidance 

should also minimize the chance of marine mammals being subject to the increased noise level of a 

service vessel in very close proximity. The Protected Species Stipulation, if applied, would make 

compliance with the guidance identified in the NTL mandatory for lessee activities.

Without implementation of the guidance mentioned above to avoid marine mammals, marine 

mammals would be vulnerable to direct noise impacts from routine vessel traffic, resulting in shortterm disruptions of movement patterns or behaviors. However, with the use of the guidelines 

mentioned above to minimize the chance of marine mammals being subjected to increased noise 

levels from service vessels, the impacts are expected to be negligible. 

Drilling and production activities, which include operating platforms and drillships, produce 

underwater noise that may be detected by marine mammals. The OCS industry’s drilling and 

production impacts are discussed in Chapters 3.1.2.2 and 3.1.3.1. Noises produced by these types 

of activities, including pile driving, are generally low frequency and have the potential to mask 

cetaceans’ reception of sounds produced for echolocation and communication. Most species of 

marine mammals in the GOM (except the Bryde’s whale) use sounds at frequencies that are 

generally higher than the dominant noise generated by offshore drilling and production activities. 

Baleen whales use low-frequency sounds that overlap broadly with the dominant frequencies of 

many industrial sounds, and there are indications that baleen whales are sensitive to low- and 

moderate- frequency sounds (Richardson et al., 1995). However, all baleen whale species, except 

for the Bryde’s whale, are considered extralimital or rare in the GOM. It is expected that noise from 

drilling activities would be relatively constant during the temporary duration of drilling. Drilling noise 

from conventional metal-legged structures and semisubmersibles is not particularly intense and is 

strongest at low frequencies, averaging 5 Hz and 10-500 Hz, respectively (Richardson et al., 1995). 

Drillships produce higher levels of underwater noise than other types of platforms. There are few 

published data on underwater noise levels near production platforms and on the marine mammals 

near those facilities (Richardson et al., 1995). However, underwater noise levels may often be low, 

steady, and not very disturbing (Richardson et al., 1995). Stronger reactions would be expected 

when sound levels are elevated by support vessels or other noisy activities (Richardson et al., 1995).

Noise from drilling and production operations may impact marine mammals similarly to other 

anthropogenic sounds in the ocean. Noise can mask important sounds from conspecifics (a 

member of the same species), mask sounds from predators, or force animals to alter their 

vocalizations. Noises may frighten, annoy, or distract marine mammals and lead to physiological 

and behavioral disturbances (Southall et al., 2007). The response threshold may depend on 
Description of the Affected Environment and Impact Analysis 4-289

whether habituation (gradual waning of behavioral responsiveness) or sensitization (increased 

behavioral responsiveness) occurs (Richardson et al., 1995). Noises can cause reactions that might 

include the disruption of marine mammals’ normal activities (behavioral and/or social disruption) and, 

in some cases, short- or long-term displacement from areas important for feeding and reproduction 

(Richardson et al., 1995). The energetic consequences of one or more disturbance-induced periods 

of interrupted feeding or rapid swimming, or both, have not been evaluated quantitatively. Some 

demographic groups may be more vulnerable to noise impacts, including females in late pregnancy 

or lactating. Human-made noise may cause temporary or permanent hearing impairment in marine 

mammals if the noise is strong enough (Southall et al.,2007). Such impairment would have the 

potential to diminish the individual’s chance for survival. Tolerance of noise is often demonstrated, 

but marine mammals may be affected by noise in difficult-to-observe ways. For example, they may 

become stressed, making the animal(s) more vulnerable to parasites, disease, environmental 

contaminants, and/or predation. Noise-induced stress is possible, but it is little studied in marine 

mammals. Tyack (2008) suggests that a more significant risk to marine mammals from sound are 

these less visible impacts of chronic exposure. Drilling and production noise would contribute to 

increases in the ambient noise environment of the GOM, but they are not expected in amplitudes 

sufficient to cause either hearing or behavioral impacts. Expected numbers of exploration and 

delineation wells, as well as development wells, projected to be drilled as a result of Alternative A, B, 

C, or D can be found in Chapters 3.1.2.2 and 3.1.3.1. 

The temporary and transient noise associated with drilling and production is not expected to 

produce more than negligible to minor impacts on marine mammals since they are not expected in 

amplitudes sufficient to cause hearing behavioral effects and due to the wide-ranging behavior of 

marine mammal species.

Although there would always be some level of incomplete information on the impacts from 

routine activities under a proposed action on marine mammals, there is credible scientific 

information, applied using acceptable scientific methodologies, to support the conclusion that any 

realized impacts would be sublethal in nature and not in themselves rise to the level of reasonably 

foreseeable significant adverse (population-level) effects. There are no data to suggest that routine 

activities from the preexisting OCS Program are significantly impacting marine mammal populations.

4.9.1.2.2 Accidental Events

Accidental, unexpected events reasonably foreseeable as a result of a proposed lease sale 

could negatively impact marine mammals. Such impacts would primarily be the result of oil spills, 

spill-response activities, and marine trash and debris.

Oil Spills

Improperly balanced well pressures that result in sudden, uncontrolled releases of fluids from 

a wellhead or wellbore could occur during any phase of development, i.e., exploratory drilling, 

development drilling, production, completion, or workover operations. In the event of an accidental 

spill, the eruption of gases and fluids may generate significant pressure waves and noise that may 
4-290 Gulf of Mexico Multisale EIS

harass, injure, or kill marine mammals, depending on their proximity to the accident. The probability 

that a marine mammal would be in the vicinity of a loss of well control at the exact moment it occurs 

is relatively small due to the wide-ranging behavior of marine mammal species, along with the low 

probability of a loss of well control (refer to Chapter 3.2.1 for more information on oil spills). There 

are relatively few studies assessing the physiological impacts of oil spills on marine mammals 

because laboratory experiments present ethical concerns. Most of the information on the potential 

impacts of oil on marine mammals comes as a result of the Exxon Valdez oil spill in Alaska and 

some limited exposure experiments (Geraci and St. Aubin, 1990). 

The impacts of an oil spill on marine mammals depend on many variables, such as location 

and size of the spill, oil characteristics, weather and water conditions, time of year, and types of 

habitats, as well as the behavior and physiology of the marine mammals themselves (Johnson and 

Ziccardi, 2006). The oil from a spill can adversely affect marine mammals by causing soft-tissue 

irritation, fouling of baleen plates, respiratory stress from the inhalation of toxic fumes, food reduction 

or contamination, direct ingestion of oil and/or tar, and temporary displacement from preferred 

habitats. The long-term impacts to marine mammal populations are poorly understood but could 

include decreased survival and lowered reproductive success (Matkin et al., 2008). An oil spill may 

physiologically stress an animal (Geraci and St. Aubin, 1980), making it more vulnerable to disease, 

parasitism, environmental contaminants, and/or predation. In any case, the impact could negatively 

impact a marine mammal population or stock.

The resident marine mammal species in the GOM include a baleen whale, toothed whales, 

delphinids, and a sirenian. Baleen whales are particularly vulnerable to direct impacts from oil 

causing fouling of baleen plates, which could impact feeding behavior (Geraci and St. Aubin, 1990). 

Marine mammals may have direct contact with oil by swimming through oil on the surface and/or 

subsurface. Surfacing behavior exposes skin, eyes, nares, and other mucus membranes to volatile 

hydrocarbons. This contact with oil could cause soft-tissue damage to eye tissues, potentially 

leading to ulcers, conjunctivitis, or blindness.

Fresh crude oil or volatile distillates release toxic vapors that, when inhaled, can lead to 

irritation of respiratory membranes, lung congestion, and pneumonia. Subsequent absorption of 

volatile hydrocarbons into the bloodstream may accumulate into such tissues as the brain and liver, 

causing neurological disorders and liver damage (Geraci and St. Aubin, 1982; Hansen, 1985; 

Geraci, 1990). Toxic vapor concentrations just above the water’s surface (where cetaceans draw 

breath) may reach critical levels for the first few hours after a spill, prior to evaporation and 

dispersion of volatile aromatic hydrocarbons and other light components (Geraci and St. Aubin, 

1982).

Studies by Geraci and St. Aubin (1982 and 1985) have shown that the cetacean epidermis 

functions as an effective barrier to many of the toxic substances found in petroleum. The cetacean 

epidermis is nearly impenetrable, even to the highly volatile compounds in oil, and when skin is 

breached, exposure to these compounds does not impede the progress of healing (Geraci and St. 

Aubin, 1985). Marine mammals are more likely to have dermal contact with weathered oil, which is 
Description of the Affected Environment and Impact Analysis 4-291

more persistent but contains fewer of the toxic compounds found in fresh oil (Geraci and St. Aubin, 

1990). Dolphins maintained at a captive site that were exposed to petroleum products initially 

exhibited a sharp decrease of food intake, along with excited behavior, eye inflammation, and 

changes in hemoglobin as well as erythrocyte content (Lukina et al., 1996). Prolonged exposure to 

oil led to a decrease of those blood parameters, changes in breathing patterns and gas metabolism, 

depressed nervous functions, and the appearance of skin injuries and burns (Lukina et al., 1996).

Trained, captive bottlenose dolphins exposed to oil could not detect light oil sheen but could 

detect thick dark oil based on visual, tactile, and presumably echolocation cues (Geraci et al., 1983; 

Smith et al., 1983). Studies of captive dolphins also showed that they completely avoided surfacing 

in slick oil after a few brief, initial tactile encounters. Reactions of free-ranging dolphins to spilled oil 

appear varied, ranging from avoidance to apparent indifference (reviewed by Geraci, 1990; Smultea 

and Würsig, 1991). In contrast to captive dolphins, bottlenose dolphins were observed off 

Galveston, Texas, during the Mega Borg oil spill in the summer of 1990 and did not consistently 

avoid entering the slick oil, which could increase their vulnerability to potentially harmful exposure to 

oil chemicals (Smultea and Würsig, 1991 and 1995). It is possible that some overriding behavioral 

motivation (such as feeding) induced dolphins to swim through the oil, that slick areas were too large 

for dolphins to feasibly avoid, or that bottlenose dolphins have become accustomed to oil due to the 

extent of oil-related activity in the GOM (Smultea and Würsig, 1995). After the Exxon Valdez spill, 

killer whales did not appear to avoid oil; however, none were observed in heavier slicks of oil (Matkin 

et al., 1994). It is unknown whether animals in some cases are simply not affected by the presence 

of oil, or perhaps are even drawn to the area in search of prey organisms attracted to the oil’s 

protective surface shadow (Geraci, 1990). The probable impacts on cetaceans swimming through 

an area of oil would depend on a number of factors, including ease of escape from the vicinity, the 

health of the individual animal, and its immediate response to stress (Geraci and St. Aubin, 1985).

Manatees concentrate their activities in coastal waters, often resting at or just below the 

surface, which may bring them in contact with spilled oil (St. Aubin and Lounsbury, 1990). Types of 

impacts to manatees from contact with oil include (1) asphyxiation due to inhalation of hydrocarbons,

(2) acute poisoning due to contact with fresh oil, (3) lowering of tolerance to other stress due to the 

incorporation of sublethal amounts of petroleum components into body tissues, (4) nutritional stress 

through damage to food sources, and (5) inflammation or infection and difficulty eating due to oil 

sticking to the sensory hairs around their mouths (Preen, 1989, in Sadiq and McCain, 1993). Direct 

contact with discharged oil likely does not impact adult manatees’ thermoregulatory abilities because 

they use blubber for insulation. Also, they exhibit no grooming behavior that would contribute to 

ingestion (USDOI, FWS, 2006). Manatees are nonselective, generalized feeders that might 

consume tarballs along with their normal food, although such occurrences have been rarely reported 

(review in St. Aubin and Lounsbury, 1990). A manatee might also ingest fresh petroleum, which 

some researchers have suggested might interfere with the manatee’s secretory activity of their 

unique gastric glands or harm intestinal flora vital to digestion (Geraci and St. Aubin, 1980; 

Reynolds, 1980). Spilled oil may also affect the quality or availability of aquatic vegetation, including 

seagrasses, upon which manatees feed.
4-292 Gulf of Mexico Multisale EIS

There have been no experimental studies and only a few observations suggesting that oil 

has harmed any manatees (St. Aubin and Lounsbury, 1990), although for a population under 

pressure from other mortality factors (e.g., vessel strikes), even a localized incident could be 

significant (St. Aubin and Lounsbury, 1990). Oil spills that may occur from OCS energy-related 

activities that reach the coast or the confines of preferred river systems and canals, particularly 

during winter (when the animals are most vulnerable physiologically), could further endanger local 

populations. The physiological costs of animals moving to colder waters to escape oiled areas may 

result in thermal stress that would exacerbate the impacts of even brief exposure to oil (St. Aubin 

and Lounsbury, 1990).

Indirect consequences of oil pollution on marine mammals include those impacts that may be 

associated with changes in the availability or suitability of food resources (Hansen, 1992). Spilled oil 

can lead to the localized reduction, disappearance, or contamination of some prey species. Prey 

species such as zooplankton, crustaceans, mollusks, and fishes may become contaminated by 

direct contact and/or by ingesting oil droplets and tainted food. Marine fishes are known to take up 

petroleum hydrocarbons from both water and food, although apparently do not accumulate high 

concentrations of hydrocarbons in tissues, and may transfer them to predators (Neff, 1990). In 

general, the potential for ingesting oil-contaminated prey organisms with petroleum-hydrocarbon, 

body-burden content is highest for benthic-feeding whales, which are not common in the GOM. The 

potential is reduced for plankton-feeding whales and is lowest for fish-eating whales (Würsig, 1990). 

Depending on the spatial scale and magnitude of an oil spill, diminished prey abundance and 

availability may cause marine mammal predators to move to less suitable areas and/or consume 

less suitable prey.

Several factors increase the probability of marine mammal/oil-spill contact, including 

(1) marine mammals often travel long distances in the GOM, increasing the geographic areas of 

potential impact; (2) marine mammals are relatively long-lived and have many years during which 

they may be exposed; (3) the life of a proposed action also means many years for an impact to 

occur; and (4) some spills would be larger, increasing the area of potential impact. It is impossible to 

know precisely which cetacean species, population, or individuals would be most impacted, to what 

magnitude, or in what numbers since each species has unique distribution patterns in the GOM and 

because of difficulties attributed to predicting when and where oil spills would occur over the 50-year 

lifetime of a proposed action. The potential impacts associated with an accidental spill may be more 

severe depending on the size of the reasonably foreseeable accidental spill. The impact from a 

reasonably foreseeable, higher volume accidental spill could potentially contribute to more significant 

and longer-lasting impacts that could include mortality and longer-lasting chronic or sublethal 

impacts.

Given the distribution of available leases and pipelines associated with a proposed lease 

sale and the distribution of marine mammals in the northern GOM, the fate of an oil spill must be 

considered relative to the region and period of exposure. Spills of any size can degrade water 

quality at least locally (Chapter 4.2, Water Quality), and residuals become available for 

bioaccumulation within the food chain. Slicks may spread at the sea surface or may migrate 
Description of the Affected Environment and Impact Analysis 4-293

underwater from the seafloor through the water column and never broach the sea surface. 

Regardless, a slick is an expanding but aggregated mass of oil that, with time, would disperse into 

smaller units as it evaporates (if at the sea surface) and weathers. As the slick breaks up into 

smaller units (e.g., slickets) and soluble components dissolve into the seawater, tarballs may remain 

within the water column. Tarballs may subsequently settle to the seafloor or attach to other particles 

or bodies in the sea. As residues of an oil spill disperse, marine mammals may be exposed via the 

waters that they inhabit, as well as via the prey they consume. For example, tarballs may be 

consumed by marine mammals and by other marine organisms that are eaten by marine mammals. 

Although marine mammals may (or may not) avoid oil spills or slicks, it is highly unlikely that they are 

capable of avoiding spill residuals in their environment at some point in their lifetime. Consequently, 

the probability that a marine mammal is exposed to hydrocarbons resulting from a spill extends well 

after the oil spill has dispersed from its initial aggregated mass. Populations of marine mammals in 

the northern GOM would likely be exposed to residuals of spilled oil throughout their lifetime.

OSRA Modeling

The OSRA modeling results, which show the probabilities of a large spill (≥1,000 bbl) 

occurring in Federal offshore waters making contact with State offshore waters, are provided in 

Figure E-20. In general terms, coastal waters of the area may be contacted by many, frequent, 

small spills (≤1 bbl); few, infrequent, moderately-sized spills (>1 and <1,000 bbl); and a single large 

spill (≥1,000 bbl) as a result of a proposed lease sale. Pipelines pose the greatest risk of a large 

spill occurring in coastal waters compared with platforms and tankers. Spill estimates over a 50-year 

time period are indicated in Table 3-18. According to Table 3-18, the majority of estimated spills 

would be small (<10 bbl). The actual number of spills that may occur in the future could vary from 

the estimated number. A spill size group for ≥10,000 bbl was not included in Table 3-18 because 

the catastrophic Deepwater Horizon oil spill (4.9 MMbbl released from the well) was the only spill in 

this size range during 1996-2010 and such a spill is not reasonably foreseeable in the future; thus, 

limited conclusions can be made from a single data point. For more information on OSRA, refer to 

Chapter 3.2.1.4 (Analysis of Offshore Spills ≥1,000 bbl). Given the distribution of available leases 

and pipelines associated with a proposed lease sale and the distribution of marine mammals in the 

northern GOM, the fate of an oil spill must be considered relative to the region and period of 

exposure. Projected oil production is 0.211-1.118 BBO and 0.547-4.424 Tcf of gas over 50 years. 

Chapter 3.2.1 details the persistence, spreading, and weathering process for offshore spills.

Depending on the timing of a spill’s occurrence in coastal waters, its impact and resulting 

cleanup activities may interrupt marine mammal migration, feeding, mating, and/or calving activities 

for extended periods (i.e., days, weeks, or months). Spills originating in or migrating through coastal 

waters of Florida may impact any marine mammal species inhabiting the area, including the West 

Indian manatee, which commonly inhabits Florida’s coastal waters. However, it is highly unlikely 

that any spill occurring in Federal offshore waters would make contact with coastal waters in Florida 

(<0.5%) where manatees are commonly found. Aside from the acute impacts noted earlier, if marine 

mammals encounter an oil slick, the displacement of marine mammals to less suitable habitats from 
4-294 Gulf of Mexico Multisale EIS

habitual feeding areas impacted by oil spills may increase vulnerability to predators, disease, or

mortality from anthropogenic causes.

The likelihood that individuals of a marine mammal population may encounter an oil slick 

resulting from a single spill during a 50-year period is greater than that of a single individual 

encountering a slick during its lifetime. It is impossible to estimate precisely what marine mammal 

species, populations, or individuals would be impacted, to what magnitude, or in what numbers, 

since each species has unique distribution patterns in the GOM and because of difficulties attributed 

to estimating when and where oil spills would occur over a 50-year period. For example, if a 

reasonably foreseeable accidental oil spill were to occur in close proximity to State waters, coastal 

species, such as manatees and some stocks of bottlenose dolphins, would most likely experience 

the impacts from this spill. If a reasonably foreseeable accidental spill were to occur in offshore 

Federal waters such as the Mississippi Canyon area, offshore species, such as sperm whales, 

would most likely experience the impacts from the potential spill since the possibility of the potential 

spill reaching coastal waters is very low.

Depending on the spill location, the species of marine mammals present, the distance of 

marine mammals in relation to the spill, and if the marine mammal accidentally ingests oil while 

feeding, impacts may be negligible to moderate when considering the probability of a marine 

mammal coming into contact with an oil spill. An example of a negligible impact would be if a group 

of oceanic bottlenose dolphins were traveling in an area where a reasonably foreseeable small 

accidental spill occurred at a well, but the group of bottlenose dolphins never encountered the oil 

and continued traveling. An example of a moderate impact would be if an individual melon-headed 

whale (PBR 13 individuals) were to ingest fresh crude oil while feeding and the impacts resulted in 

physical injury or mortality.

Recently, NMFS announced a proposed rule to list the Gulf of Mexico Bryde’s whale as 

endangered under the ESA (Federal Register, 2016e). Impacts to the Gulf of Mexico Bryde’s 

whales’ habitat or to individual Bryde’s whales exposed to an oil spill or associated spill-response

activities would increase the risk of extinction of this distinct population segment, which would 

elevate the impact for this analysis to major. For purposes of this Multisale EIS, BOEM has 

analyzed the impacts of reasonably foreseeable activities that could occur as part of a proposed 

action. Although there is limited activity in the EPA, both the habitat or individual Gulf of Mexico 

Bryde’s whales could be exposed to an accidental spill depending on the timing, size, and proximity 

of the oil spill to the primary habitat, as well as various factors that influence the fate and transport of 

spilled oil (e.g., oil characteristics, weather and water conditions, time of year, etc.). Although the 

possibility of Gulf of Mexico Bryde’s whales being exposed to an oil spill exists, the probability of an

oil spill occurring and contacting the Gulf of Mexico Bryde’s whale’s primary habitat as part of a 

proposed action is low. Based on this low probability, along with the best science available for the 

Gulf of Mexico Bryde’s whale distribution, and considering the current moratorium in the EPA, it is 

not likely that a Bryde’s whale would be exposed to an accidental oil spill as part of a proposed 

action.
Description of the Affected Environment and Impact Analysis 4-295

Spill-Response Activities

Spill-response activities that may impact marine mammals include increased vessel traffic, 

the use of dispersants, and remediation activities (e.g., controlled burns, skimmers, boom, etc. [refer 

to Chapter 3.2.8]). The increased human presence after an oil spill (e.g., vessels) would likely add 

to changes in behavior and/or distribution, thereby potentially stressing marine mammals further and 

perhaps making them more vulnerable to various physiologic and toxic effects of spilled oil. In 

addition, the large number of response vessels could place marine mammals at a greater risk of 

vessel collisions, which could cause fatal injuries. Manatees are particularly vulnerable to vessel 

collisions that may result from increased vessel traffic. Vessel noise would also increase as a result 

of increased vessel activity and could result in behavioral changes in some individuals.

Spill-response activities could also include the application of dispersants to the affected area. 

Dispersants are designed to break oil on the water’s surface into minute droplets, which then break 

down in seawater (refer to Chapter 3.2.8.2.2). Essentially little is known about the impacts of oil 

dispersants on cetaceans, except that removing oil from the surface would reduce the risk of contact 

and render it less likely to adhere to skin, baleen plates, or other body surfaces (Neff, 1990). A 

laboratory experiment by Wise et al. (2014) found that chemical dispersants used during the 

Deepwater Horizon oil-spill response were cytotoxic to sperm whale cells and could lead to fibrosis 

and impaired organ function. However, it is difficult to determine how these exposures relate to the 

actual exposures in the GOM since there is no known accurate method to measure the amount of 

whale exposure to dispersants (Wise et al., 2014). The acute toxicity of most oil dispersant 

chemicals is considered to be low relative to the constituents and fractions of crude oil and refined 

products, and a study by Wells (1989) showed that the rate of biodegradation of dispersed oil is 

equal to or greater than that of undispersed oil. Varieties of aquatic organisms readily accumulate 

and metabolize surfactants from oil dispersants; however, metabolism of surfactants is thought to be 

rapid enough that there is little likelihood of food chain transfer from marine invertebrates and fish to 

predators, including marine mammals (Neff, 1990). Impacts from dispersants are unknown but may 

be irritants to tissues and sensitive membranes (NRC, 2005). One assumption concerning the use 

of dispersants is that the chemical dispersion of oil would considerably reduce the impacts to marine 

mammals, primarily by reducing their exposure to petroleum hydrocarbons (French-McCay, 2004; 

NRC, 2005). However, the impacts to marine mammals from chemical dispersants could include 

nonlethal injury (e.g., tissue irritation and inhalation), long-term exposure through bioaccumulation, 

and potential shifts in distribution from some habitats.

Some remediation activities that could impact marine mammals include the use of skimmers, 

booms, and controlled burns. Impacts from skimmers could be through capture and/or entrainment. 

Booming operations could potentially impact marine mammals, particularly manatees, as they are 

close to shore and known to explore and interact with objects in their environment (Hartman, 1979). 

Lines used to anchor booms are more likely than the boom itself to impact manatees, by 

entanglement. Controlled burns could impact marine mammals if they were in the burning oil; 

however, it is expected that animals would avoid the area once it is ignited. In both skimming and 

controlled burning activities, the use of trained observers is common and reduces the likelihood of 
4-296 Gulf of Mexico Multisale EIS

impacts to marine mammals. Because of the low probability of marine mammals being in the vicinity 

of an OCS oil- and gas-related, oil-spill response activity due to their wide-ranging behavior as well 

as the likelihood of having trained observers looking for marine mammals, impacts are expected to 

be negligible to moderate. An example of a negligible impact would be if a small group (5-8 

individuals) of Atlantic spotted dolphins was traveling in an area where remediation activities are 

being conducted to control an oil spill, but the group of Atlantic spotted dolphins never encountered 

the remediation activities and continued traveling. An example of a moderate impact would be if a 

small group (5-8 individuals) of spinner dolphins (PBR 62 individuals) encountered dispersants while 

traveling and experienced a nonlethal injury via inhalation at the water-surface interface. Although it 

may have a localized impact on that particular group of spinner dolphins, it would not diminish the 

continued viability of the population, including the annual rates of recruitment or survival.

Marine Trash and Debris

Marine mammal ingestion of, and entanglement in, accidentally released industry debris is a 

concern (refer to Chapter 3.2.7). A marine mammal could suffer reduced feeding and reproductive 

success, and potential injury, infection, and death from entanglement in marine debris. The debris 

items most often found entangling animals are net fragments and monofilament line from 

commercial and recreational fishing boats, as well as strapping bands and ropes from a variety of 

vessels. Plastic bags and small plastic fragments are the most commonly reported debris items in 

the digestive tracts of cetaceans and manatees (e.g., Barros and Odell, 1990; Tarpley and Marwitz, 

1993; Laist, 1997); however, ingestion of net materials can also be fatal (Jacobsen et al., 2010). 

Sheavely (2007) reports that as much as 49 percent of marine debris is considered land based. 

There are many types of materials used in offshore energy production, and some of this material is 

accidentally lost overboard from service vessels or OCS structures where marine mammals could 

ingest it or become entangled in it. The offshore oil and gas industry was shown to contribute 

13 percent of the debris found at the Padre Island National Seashore (Miller et al., 1995). Many of 

the plastics used by industry could withstand years of saltwater exposure without disintegrating or 

dissolving.

To address the potential impacts of marine debris, BSEE issued NTL 2015-BSEE-G03, 

“Marine Trash and Debris Awareness and Elimination,” which provides information on the marine 

trash and debris awareness training video and slide show, and both postal and email addresses for 

submitting annual training reports. The information provided is intended to greatly minimize the 

amount of debris that is accidentally lost overboard by offshore personnel; however, these directives 

do not eliminate the accidental release of debris, which could impact an individual or group of 

individuals if they become entangled in or accidentally ingest released debris. The Protected 

Species Stipulation, if applied, would make compliance with the guidance identified in the NTL 

mandatory for lessee activities.

Without implementation of mitigations, marine mammals would be vulnerable to direct 

impacts from entanglement in or ingestion of OCS marine debris. The impacts from OCS marine 

debris with marine trash and debris guideline mitigations are expected to be negligible. 
Description of the Affected Environment and Impact Analysis 4-297

4.9.1.2.3 Cumulative Impacts

The cumulative analysis considers past, present, and foreseeable future human and natural 

activities that may occur and adversely affect marine mammals in the same general area that may 

be affected by a proposed action.

The major impact-producing factors relative to a proposed action are described in 

Chapter 4.9 (Protected Species) above in Table 4-18. Chapters providing supportive material for 

the marine mammals analysis include Chapters 4.9.1 (Marine Mammals, Description of the Affected 

Environment), 3.3.1.3 (Cumulative Exploration and Delineation), 3.3.1.4 (Cumulative Development 

and Production Drilling), 3.3.1.7 (Transport), 3.3.1.8 (Discharges and Wastes), 3.1.9 and 3.3.2.7

(Noise and Noise from Non-OCS Oil- and Gas-Related Sources), 3.3.1.10 (Coastal Infrastructure), 

3.3.1.9 (Decommissioning and Removal Operations), and 3.2.1 (Oil Spills).

OCS Oil- and Gas-Related Impacts

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

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

described under the “Routine Activities” and “Accidental Events” sections above and include the 

following: decommissioning; operational discharges; G&G activities; noise; transportation; marine 

debris; and accidental oil spill and spill-response activities. The cumulative impact of these ongoing 

OCS energy-related activities on marine mammals is expected to result in a number of chronic and 

sporadic sublethal effects (i.e., behavioral effects and nonfatal exposure to or intake of OCS oil- and 

gas -related contaminants or discarded debris) due to the fact that these activities may stress and/or 

weaken individuals of a local group or population and may predispose them to infection from natural 

(e.g., bacteria) or anthropogenic (e.g., marine debris) sources.

As previously discussed in Chapter 4.9.1.2.1 (Routine Activities), the use of explosives is the 

preferred method for the severance of structures from their foundations in the GOM. Explosive 

structure removals put loud but temporary noise into the ocean, and these can occur in Federal or 

State waters. The shock wave and blast noise from explosions are of most concern to marine 

mammals. Depending on the intensity of the shock wave and size and depth of the animal, an 

animal can be injured or killed. Farther from the blast, an animal may suffer nonlethal physical 

impacts. Outside of these zones of death and physical injuries, marine mammals may experience 

hearing-related impacts with or without behavioral responses. A limited amount of information is 

available on the impacts of explosions on marine mammals (O’Keeffe and Young, 1984; Ketten, 

1998). However, BOEM (then BOEMRE) issued “Decommissioning Guidance for Wells and 

Platforms” (NTL 2010-G05), which specifies and references mitigation requirements in the current 

ESA and MMPA guidance and which should minimize the chance of a marine mammal being 

impacted from explosive severance activities. “Decommissioning Guidance for Wells and Platforms” 

(NTL 2010-G05) is discussed in Chapter 4.9.1.2.1 (Routine Activities).

Industry noise sources include seismic operations, fixed platforms and drilling rigs, drilling 

ships, low-flying aircraft, vessel traffic, and explosive operations, particularly for structure removal. 
4-298 Gulf of Mexico Multisale EIS

Chapter 3.1 describes the offshore infrastructure and activities (impact-producing factors) 

associated with a proposed lease sale. A discussion of all activities that are projected from past, 

present, and future lease sales during a 70-year activity period (2017-2086) can be found in 

Chapter 3.3.1. 

Accidental events related to a proposed action, as discussed above, have the potential to 

have adverse, impacts to marine mammal populations in the GOM.

Oil spills may cause chronic (long-term lethal or sublethal oil-related injuries) and acute (spillrelated deaths occurring during a spill) impacts on marine mammals. Long-term impacts include 

(1) decreases in prey availability and abundance because of increased mortality rates, (2) change in 

age-class population structure because certain year-classes were impacted more by oil, 

(3) decreased reproductive rate, and (4) increased rate of disease or neurological problems from 

exposure to oil (Harvey and Dahlheim, 1994). The impacts of cleanup activities are unknown, but 

increased human presence (e.g., vessels) could add to changes in marine mammal behavior and/or 

distribution, thereby additionally stressing animals, and perhaps making them more vulnerable to 

various physiologic and toxic impacts. However, there is no supporting evidence that marine 

mammal populations of the GOM are impacted by the cumulative OCS oil-and-gas related activities. 

Therefore, the incremental cumulative contribution of OCS- oil and gas-related activities is expected 

to have negligible to moderate impacts.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS energy-related activities that may affect marine mammal populations include 

pollution, marine debris, explosive severance of structures in non-OCS State waters as part of State 

oil- and gas-related activities, vessel traffic and related noise (e.g., from military operations, 

commercial shipping, and research vessels); commercial and recreational fishing (Chapters 4.10

and 4.11), scientific research, diseases, UMEs, and natural phenomena. Specific types of impactproducing factors considered in this cumulative analysis include noise from numerous sources, 

pollution, ingestion and entanglement in non-OCS marine debris, and vessel strikes.

Pollution in the ocean comes from many point (e.g., non-OCS discharges, factories, 

wastewater treatment facilities) and nonpoint (e.g., drainage, precipitation, land runoff) sources, and 

the GOM is certainly no exception. The drainage of the Mississippi River results in massive 

amounts of chemicals and other pollutants being constantly discharged into the GOM. The zone of 

hypoxia on the Louisiana-Texas shelf is one of the largest areas of low oxygen in the world’s coastal 

waters (Murray, 1997) and does not support adequate food resources due to its low oxygen levels 

(refer to Chapter 3.3.2.12). Primarily, bottlenose dolphins and manatees are most at risk for 

nearshore pollution. Bottlenose dolphins have been reported having very high levels of 

contaminants, including heavy metals, in tissue samples (Borrell, 1993). Since other marine 

mammals are not commonly found in coastal waters, they are less likely to be impacted by 

nearshore pollution. Prey species also affect the influence of pollution on marine mammals. 

Biomagnification in fish results in the generally higher contaminant levels in fish-eating marine 
Description of the Affected Environment and Impact Analysis 4-299

mammals (Gray, 2002). Manatees are herbivores, but pollution and habitat degradation may impact 

the manatee. Manatees are exposed to herbicides by ingesting aquatic vegetation containing 

concentrations of these compounds (O’Shea et al., 1984). The propensity of manatees to aggregate 

at industrial and municipal outfalls also may expose them to high concentrations of contaminants 

(Stavros et al., 2008). Antifouling bottom paint on the hulls of boats has been linked to the release of 

contaminants (Schiff et al., 2004). For coastal dolphins and especially manatees that are very well 

known to frequent marinas and that scratch on the hulls of vessels, areas with high concentrations of 

vessels may have extremely polluted waters. However, there are non-OCS regulations that limit the 

discharge of pollutants in State waters (e.g., NPDES). Although there are a number of studies 

assessing the impacts of chemicals and pollutants on marine mammals, there is no conclusive 

evidence that these impacts are affecting marine mammals on a population level. Therefore, 

impacts to marine mammals from non-OCS pollutants would be negligible to minor. 

Ingestion of, or entanglement in, non-OCS marine debris is a global concern for marine 

organisms. Estimates indicate that approximately 6.4 million tons of marine litter is dumped in 

oceans every year, resulting in an estimated 13,000 pieces of litter per square kilometer of ocean 

(United Nations Environment Programme, 2005). There is general consensus that land-based 

sources are the dominant origin of marine debris, contributing up to 49 percent, with marine or 

undetermined sources contributing the remainder (Sheavly and Register, 2007). Plastic bags and 

small plastic fragments are the most commonly reported debris items in the digestive tracts of 

cetaceans and manatees (e.g., Barros and Odell, 1990; Tarpley and Marwitz, 1993; Laist, 1997); 

however, ingestion of net materials can also be fatal (Jacobsen et al., 2010). Plastics are very 

persistent, yet they are not immune to degradation. Microplastics, or microscopic plastic particles, 

may be ingested by a wide range of organisms, and there are indications that microplastics are 

propagated over trophic levels of the marine food web (Farrell and Nelson, 2013; Setälä et al., 

2014). Therefore, marine mammals may be ingesting plastic particles through consumption of 

various prey sources.

Entanglement in marine debris can cause decreased swimming ability, disruption in feeding, 

life-threatening injuries, and death. The debris items most often found entangling animals are net 

fragments and monofilament line from commercial and recreational fishing boats, as well as 

strapping bands and ropes from a variety of vessels. Impacts from non-OCS marine debris are 

expected to be negligible to major. An example of a negligible impact would be if small pieces of 

marine debris were ingested by a marine mammal species and then later passed through their 

digestive tract with no complications. An example of a major impact would be if a discarded 

monofilament fishing net were to cause physical injury or mortality to a marine mammal species with 

a low population estimate (e.g., Bryde’s whale).

Structure removals that take place in GOM State waters are under the jurisdiction of the 

COE. Impacts to marine mammals from these activities are similar to the impacts discussed in the 

“OCS Oil- and Gas-Related Impacts” section in Chapter 4.9.1.2, and they may potentially include 

injury or death from shockwave depending on the intensity of the shock wave and size and depth of 
4-300 Gulf of Mexico Multisale EIS

the animal; nonlethal physical effects; and hearing-related effects with or without behavioral 

responses.

Numerous sources of aircraft fly over the coastal and offshore areas. The air space over the 

GOM is used extensively by DOD for conducting various air-to-air and air-to-surface operations. 

Eleven military warning areas and six water test areas are located within the GOM, as stated in NTL 

2009-G06, “Military Warning and Water Test Areas” (Figure 2-7). Additional activities, including 

vessel operations and ordnance detonation, also may impact marine mammals. Subject to Federal 

Aviation Administration guidelines, private and commercial air traffic further traverse these areas and 

have the potential to cause impacts to marine mammals.

Commercial fishery interactions are a concern for marine mammals because they may be 

injured or killed by commercial fishing gear. Marine mammals can either get caught on longline 

hooks or can be entrained into a net by a shrimp boat or groundfish vessel. There is also the 

chance of entanglement by lines from crab traps to buoys. Gillnets, which have now been banned in 

many places around the GOM, have been reported to take marine mammals. However, recent 

reports of these impacts are uncommon. Depending on the type of fishing gear and the number of 

marine mammals affected by the interaction with the fishing gear, impacts would be negligible to 

major. An example of a negligible impact would be if a marine mammal species observed fishing 

activities, made no behavior change, and ultimately had no interaction with the fishing gear or 

activities. An example of a major impact would be if a commercial fishing net were to cause physical 

injury or mortality to a marine mammal species with a low population estimate (e.g., killer whale).

All manner of commercial shipping vessels, commercial fishing vessels, military ships, 

research ships, recreational craft, and others are always present in the GOM and increases the 

possibility of vessel collisions between vessels and marine mammals. Slow-moving marine 

mammals or those that spend extended periods of time at the surface might be expected to be the 

most vulnerable (Vanderlaan and Taggert, 2007). In 2014, approximately 85 percent of humancaused manatee mortalities in Florida were attributed to collisions with watercraft (State of Florida, 

Fish and Wildlife Conservation Commission, 2015c). Noise from various non-OCS vessels could 

interfere with marine mammal communication either by masking important sounds from conspecifics, 

masking sounds from predators, or by forcing animals to alter their vocalizations (Tyack, 2008).

Some factions of the boating public, mainly recreational fishermen and boaters, create 

adverse impacts by paying too much attention to marine mammals. Reports of harassment, 

inappropriate feeding, and even attempting to swim with marine mammals are common. Dolphins 

have been injured and killed after becoming accustomed to being fed by humans. Animals become 

sick from eating the “food” that people throw. Very close approaches by boats are likely major 

causes of stress in marine mammals, as is chasing and following.

Scientific research can impact marine mammal species. Numerous marine mammal 

research cruises have been conducted, and permitted activities have included tagging and biopsy 

sampling. The U.S. protocols are always in place to keep the mammals safe, but some of the 
Description of the Affected Environment and Impact Analysis 4-301

research techniques do involve harassment and possible stress to the animal. Scientific seismic 

studies often use the same tools and techniques as industry seismic work, which could have the 

same impacts to marine mammals. Scientific groundfish or shrimp cruises can entrap a dolphin in a 

net just as commercial fisheries can. In 2011, a scientific cruise that was associated with NRDA

killed six dolphins while sampling fish with nets. Scientific aerial surveys are also periodically 

conducted in the GOM, and aircraft can startle marine mammals. Circling pods for identification may 

stress multiple individuals in a pod. Such marking techniques as freeze branding were used in the 

past to do mark-recapture studies. This required the live capture and branding of dolphins. Both the 

Navy and the public-display industry took bottlenose dolphins from the GOM in years past. A 

moratorium on live captures has been in effect for several years, as captive breeding programs have 

become successful enough to provide dolphins for aquariums and zoos.

Occasionally, numbers of marine mammals strand, either alive or already dead. Die-offs 

happen infrequently but can seriously deplete small, discrete stocks. The causes of die offs are not 

always well known and vary by event. Some appear to be triggered by natural events (i.e., 

unusually cold weather) but others are suspected to at least be indirectly caused by pollution of 

various contaminants. Exposure to certain compounds may weaken the natural immunity of marine 

mammals and make them susceptible to viruses and diseases that would normally not affect them. 

Certain viruses, such as morbilliviruses, which affect the lungs and brain in cetaceans, are being 

observed more frequently than in the past (USDOC, NMFS, 2015e). A red-tide event that began in 

southwest Florida in late September 2012 claimed the highest number of red-tide-related manatee 

deaths in a single calendar year on record (State of Florida, Fish and Wildlife Conservation 

Commission, 2015c). The NMFS may declare a large die-off to be an UME, which is defined under 

the MMPA as “a stranding that is unexpected; involves a significant die-off of any marine mammal 

population; and demands immediate response” (USDOC, NMFS, 2015e). The causes for nearly 

20 UMEs that have been declared by NMFS in the GOM region since 1991 have either been due to 

infectious diseases or biotoxins, ecological factors, or were declared undetermined. However, some 

strandings become available. The most recent information for UMEs in the GOM can be found on 

NMFS’ website (USDOC, NMFS, 2015f).

Impacts from climate change to marine mammals have become a concern, and responses 

both at the individual and population level of marine mammal species to climate change are poorly 

understood (Evans and Bjørge, 2013). Making predictions about future impacts becomes even more 

speculative. In the last 15 years, a number of marine mammal scientists have attempted to do this 

(Tynan and DeMaster, 1997; International Whaling Commission, 1997; Würsig et al., 2002; 

Learmonth et al., 2006; Simmonds and Isaac, 2007; Huntington and Moore, 2008; Kovacs and 

Lyderson, 2008; Laidre et al., 2008; International Whaling Commission, 2009; MacLeod, 2009; 

Evans et al., 2010; Kaschner et al., 2011). Some of the major hypothesized impacts to marine 

mammals from climate change are changes in water temperatures, which may result in distribution 

changes, changes to physical habitat, changes to the food web, thermal Intolerance (e.g., heat 

stress), and susceptibility to increased diseases and contaminants (Evans and Bjørge, 2013). There 

is also concern that ocean acidification from rising carbon dioxide levels will decrease sound 

absorption in oceans, thereby causing amplified levels of ambient noise (Gazioglu et al., 2015), 
4-302 Gulf of Mexico Multisale EIS

which would negatively affect marine mammals. Further, increased sea-surface temperatures likely 

enhance the magnitude and frequency of harmful algal blooms and their associated toxins, which 

have shown to negatively impact ecosystem health (O’Neil et al., 2012).

Lastly, tropical storms and hurricanes are normal occurrences in the GOM and along the 

Gulf Coast. Generally, the impacts have been localized and infrequent. However, the GOM has 

been hit extremely hard by very powerful hurricanes. Few areas of the coast have not suffered 

some damage in 2004 and 2005, and activities in the GOM have also been severely impacted. In 

2004, Hurricane Ivan took a large toll on oil and gas structures and operations in the GOM and 

caused widespread damage to the Alabama-Florida Panhandle coast. In 2005, Hurricanes Katrina, 

Rita, and Wilma reached Category 5 strength in the GOM, and these hurricanes were followed in 

2008 by Hurricane Gustav and by Hurricane Isaac in 2012. These storms caused damage to all five 

of the Gulf Coast States and damage to structures and operations both offshore and onshore. The 

actual impacts of these storms on marine mammals in the GOM have not yet been determined and, 

for the most part, may remain very difficult to quantify.

The impacts of such natural disasters on marine mammal populations are poorly understood 

and difficult to assess due to the limited predictability of storm occurrence, course, strength, and 

location of impact. Some immediate and direct impacts of hurricanes on marine mammals have 

been documented, such as the temporary displacement or stranding of individuals (e.g., dugongs 

[Dugong dugon; Marsh, 1989]; pygmy killer whales [Feresa attenuata; Mignucci-Giannoni et al., 

1999]; and bottlenose dolphins [Tursiops truncatus; Rosel and Watts, 2008]). Under some 

circumstances, hurricanes can cause massive mortalities of fish and destruction of their habitats in 

coastal and estuarine ecosystems (Tabb and Jones, 1962) causing dolphins to be temporarily 

displaced when seeking new foraging areas.

Evaluation of long-term impacts of severe storms to marine mammals requires multi-year 

studies to be in place prior to a disaster to adequately measure the impacts (Smith et al., 2013), in 

which there are few. Langtimm et al. (2006) found that the destruction of habitat in important 

foraging areas following severe tropical systems may have indirectly increased mortality in Florida 

manatees (Trichechus manatus latirostris) (Langtimm et al., 2006). However, some evaluations of 

long-term impacts to coastal marine mammals have documented their resilience and adaptability. 

Miller et al. (2010) investigated the impacts of Hurricane Katrina on bottlenose dolphin reproduction 

in the Mississippi Sound area. The study reported an increase in reproduction, which was attributed, 

in part, to a potential increase in prey abundance in the area following a widespread decrease in 

annual fisheries landings in the area during the year following the storm (Miller et al., 2010). A 

similar study in the same area by Smith et al. (2013) also found that bottlenose dolphin foraging 

activity increased significantly following the passage of Hurricane Katrina, suggesting that there may 

have been an increase in feeding opportunity, prey abundance, and/or a need for increased food 

consumption likely attributed to the same decrease in annual fisheries landings.

Cumulative incremental impacts to marine mammals from a proposed lease sale, when 

taking into consideration the potential impacts of the Deepwater Horizon explosion, oil spill, and 
Description of the Affected Environment and Impact Analysis 4-303

response, non-OCS oil- and gas-related factors, the minimization of OCS oil- and gas-related 

impacts through lease stipulations and regulations, and the wide-ranging behavior of marine 

mammals, would be expected to be negligible with no anticipated population-level impacts.

4.9.1.2.4 Incomplete or Unavailable Information

Throughout this chapter, where information was incomplete or unavailable, BOEM complied 

with its obligations under NEPA to determine if the information was relevant to reasonably 

foreseeable significant adverse impacts; if so, whether it was essential to a reasoned choice among 

alternatives; and, if it was essential, whether it can be obtained and whether the cost of obtaining the 

information is exorbitant, as well as whether credible scientific information applied using generally 

accepted scientific methodologies can be used in its place (40 CFR § 1502.22). BOEM has made 

conscientious efforts to comply with the spirit and intent of NEPA and to be comprehensive in its 

analyses of potential environmental impacts.

BOEM has identified incomplete information regarding impacts of the Deepwater Horizon

explosion, oil spill, and response on marine mammals in the GOM. This incomplete information may 

be relevant to the evaluation of adverse impacts because it could provide changes in the baseline 

environmental conditions for marine mammals in the affected environment from the Deepwater 

Horizon oil spill and response, exacerbating any impacts from a proposed action. In NEPA, the term 

“baseline” usually consists of the pre-project environmental conditions. For the purpose of this 

Multisale EIS, the baseline is the condition of resources in the vicinity of the project as they exist at 

the time this environmental analysis began. The injuries assessed within the PDARP/PEIS do not 

necessarily equate to the current baseline as defined in NEPA. Quantification of a new baseline has 

several difficulties, including the lack of pre-spill data, the interpretation of post-spill data, and other 

potential parameters that may have contributed to the quantification of the new baseline. The 

difference between the state of the resources in an earlier injury assessment and in a current

baseline assessment equals any recovery that may have occurred. In addition, the injury 

assessment reviews a worst-case impact scenario while a baseline assessment determines a 

reasonable understanding of the current state of the resource.

On December 13, 2010, NMFS declared a UME for cetaceans (whales and dolphins) in the 

Gulf of Mexico that was later closed in May 2016. Evidence of the UME was first noted by NMFS as 

early as February 2010, before the Deepwater Horizon explosion, oil spill, and response. During this 

UME, spatial and temporal boundaries of stranded cetaceans were defined as far as the Florida 

Panhandle and west to the Louisiana-Texas border (USDOC, NMFS, 2015f). However, these 

boundaries were redefined by NOAA, based upon analysis of stranding data, to include all 

cetaceans that stranded in Alabama, Mississippi, and Louisiana from March 2010 through July 2014 

and all cetaceans other than bottlenose dolphins that stranded in the Florida Panhandle (Franklin 

County through Escambia County) from March 2010 through July 2014. The NOAA has claimed 

that these boundaries could be adjusted in the future based upon the availability of new results or 

analyses (USDOC, NMFS, 2016b). As of May 2016, a total of 1,141 cetaceans (5% stranded alive 

and 95% stranded dead) stranded during the UME between Franklin County, Florida, and the 
4-304 Gulf of Mexico Multisale EIS

Louisiana/Texas border. These stranding numbers are significantly greater than reported in past 

years; ,though it should be further noted that stranding coverage (i.e., effort in collecting strategies) 

has increased considerably due to the Deepwater Horizon explosion, oil spill, and response 

(USDOC, NMFS, 2016b).

The UME investigation and the Trustees determined that the Deepwater Horizon explosion, 

oil spill, and response resulted in the death of marine mammals and is the most likely explanation of 

the persistent, elevated stranding numbers in the northern Gulf of Mexico after the spill. Data have 

supported that the adrenal and lung disease observed in dolphins was most likely due to exposure to 

petroleum products from the oil spill. This has resulted in both dolphin mortalities, which peaked 

from March 2010 through July 2014, and fetal loss. Research, while ongoing, suggests that the 

effect on these populations has not ended, with evidence of failed pregnancies found in 2015 

(USDOC, NMFS, 2016b).

Although data have suggested that exposure to petroleum products may result in 

reproductive failure, other factors have the potential to affect marine mammal reproduction and were 

also observed during the timeframe of this UME. In addition to investigating all other potential 

causes, scientists are still investigating what role Brucella plays in the northern Gulf of Mexico UME. 

Brucella is a gram-negative, intracellular bacterium that has been isolated from many marine 

mammal species globally (Nymo et al., 2011; Guzmán-Verri et al., 2012; Hernández-Mora et al., 

2013) and that may cause placentitis and sporadic late-term abortion (Miller et al., 1999; Dagleish 

et al., 2008; Guzmán-Verri et al., 2012; Hernández-Mora et al., 2013). As of October 27, 2015, 

68 out of 210 dolphins tested were positive or suspected positive for Brucella. More detail on 

Brucella and its role in the UME can be found on NMFS’ website (USDOC, NMFS, 2016b). Future 

investigations on immune function in Gulf of Mexico dolphins are needed to determine whether 

exposure to hydrocarbons during the Deepwater Horizon oil spill or other environmental stressors 

may have caused an increased susceptibility to infectious agents that affect the fetal-placental unit 

or other conditions leading to late-term fetal loss (Colegrove et al., 2016). Furthermore, a study by 

Carmichael et al. (2012) suggested that natural stressors combined with the Deepwater Horizon

explosion, oil spill, and response may have created a “perfect storm” for bottlenose dolphins in the 

northern Gulf of Mexico. Many coastal species in the northern Gulf of Mexico, including dolphins, 

experienced unusually harsh winter conditions in early 2010, which were followed by the Deepwater 

Horizon explosion, oil spill, and response. A third potential stressor was introduced in January 2011 

when large volumes of cold freshwater, associated with melt water from an unusually large winter 

snowfall near the Mobile Bay watershed, entered the nearshore coastal systems very rapidly. This 

event happened days prior to the start of unusually high numbers of perinatal (near term to neonatal) 

bottlenose dolphin mortalities in the northern Gulf of Mexico from January to April 2011.

Various environmental stressors that are known to cause death to marine mammals were 

also present during the Deepwater Horizon explosion, oil spill, and response, but it is unclear at this 

time what level of impact these stressors contributed to the increase in strandings (Carmichael et al., 

2012). According to NMFS’ website referenced above, evidence of the UME was first documented 

by NMFS as early as March 2010, a month prior to the Deepwater Horizon explosion and oil spill. 
Description of the Affected Environment and Impact Analysis 4-305

The NMFS has also documented an additional 12 UMEs that have been previously declared in the 

GOM for cetaceans (an additional 7 specific to manatees only) since 1991 (USDOC, NMFS, 2015d). 

However, studies published from the NRDA process evaluating the possible impacts of the 

Deepwater Horizon explosion, oil spill, and response on bottlenose dolphins exposed to oiling have 

shown overall poor health and prevalence of poor body condition, disease, and abnormalities as 

compared with bottlenose dolphins in the Gulf of Mexico that were not exposed to oiling (Schwacke 

et al., 2013; Venn-Watson et al., 2015). Bacterial pneumonia was also identified from dolphins 

before and during the UME but it was detected more in the UME dolphins (Venn-Watson et al., 

2015). While this information may ultimately be useful in expanding the available knowledge on 

baseline environmental conditions following the Deepwater Horizon explosion, oil spill, and 

response, it remains difficult to draw specific conclusions regarding the current overall bottlenose 

dolphin population in the GOM.

Even with recent publications, such as the Venn-Watson et al. (2015) marine mammal study, 

the best available information on impacts to GOM marine resources does not yet provide a complete 

understanding of the impacts of the oil spill and active response/cleanup activities from the 

Deepwater Horizon explosion and oil spill on marine resources as a whole in the GOM. Relevant 

data on the status of marine mammal populations after the UME and Deepwater Horizon explosion, 

oil spill, and response may take years to acquire and analyze, and impacts from the Deepwater 

Horizon explosion, oil spill, and response may be difficult or impossible to discern from other factors. 

For example, even 20 years after the Exxon Valdez spill, the long-term impacts to marine mammal 

populations are still being investigated (Matkin et al., 2008). Therefore, it is not possible for BOEM 

to obtain this information within the timeline contemplated for analysis in this Multisale EIS, 

regardless of the cost or resources needed.

Unavailable information provides challenges in understanding the baseline conditions and 

changes within marine mammal populations. The impacts of tropical storms and hurricanes in the 

GOM have never been determined and the impacts remain very difficult to quantify. The impacts 

associated with the Deepwater Horizon explosion, oil spill, and response makes an understanding of 

the cumulative impacts less defined. The process, timeline, and determination of NMFS’ proposal to 

list the Bryde’s whale as endangered is unknown, but it is not essential to a reasoned choice among 

alternatives because, if listed, BOEM would need to consult under ESA Section 7 (refer to

Chapter 5.2). BOEM used existing information and reasonably accepted scientific methodologies to 

extrapolate from publicly available information on marine mammals in completing the relevant 

analysis of marine mammal populations. There are existing leases in the GOM with ongoing or the 

potential for exploration, drilling, and production activities. In addition, non-OCS oil- and gas-related 

activities would continue to occur in the GOM irrespective of a proposed action (e.g., fishing, military 

activities, and scientific research). Therefore, BOEM concludes that the unavailable information 

from these events may be relevant to foreseeable significant adverse impacts to marine mammals 

because the full extent of impacts on marine mammals is not known. However, BOEM has 

determined that the information is not essential to a reasoned choice among alternatives for this 

Multisale EIS (including the No Action and Action Alternatives) because none of the sources reveal 
4-306 Gulf of Mexico Multisale EIS

reasonably foreseeable significant adverse impacts to marine mammals not otherwise considered in 

this Multisale EIS.

4.9.1.2.5 Alternatives A, B, C, and D

With respect to marine mammal species, the effects associated with selection of any of the 

alternatives would be equivalent because of the diversity and distribution of marine mammal species 

throughout the potential areas of interest. The preceding analyses assumed a wide distribution of 

species and considered impacts to marine mammal species occurring in a wide range of habitats 

across all planning areas. While a proposed WPA lease sale (Alternative C) would be in a smaller 

area with less projected activity than a proposed regionwide (Alternative A) or proposed CPA/EPA 

lease sale (Alternative B) as described in Chapter 3, marine mammal species are widely distributed 

throughout the planning areas and may travel great distances across the GOM. As such, activities 

isolated to specific planning areas pose similar potential impacts to individuals as do activities 

occurring in all planning areas. Therefore, a similar mix of species would be exposed to the 

analyzed impact-producing factors, regardless of the specific action alternative selected. For 

example, if a marine mammal species were to be accidentally struck by an OCS vessel, it would 

have the same impact to that individual and its respective population estimate in the WPA as it 

would if it were struck in the CPA or EPA. Although it can be speculated that a smaller leased area 

resulting in less projected OCS oil- and gas-related activity would decrease the likelihood of OCS oiland gas-related activities impacting marine mammal populations, there are not enough conclusive 

data on the density and distributions of marine mammal populations in the GOM throughout the year 

to support that speculation. Because this information is not available and because marine mammals 

have exhibited wide-ranging behaviors in the GOM, it is very difficult to predict where in the GOM a 

particular marine mammal species will be throughout the year. For instance, the Florida manatee 

has been known to occur mostly in the State waters of Florida in the EPA, which has very little OCS 

oil- and gas-related activity. However, there have been multiple manatee sightings in deep water

from OCS oil- and gas-related activities occurring in the CPA.

The activities proposed under Alternatives A, B, C, and D could directly impact marine 

mammal species within the GOM and contribute incrementally to the cumulative effects on these 

species. Although there would always be some level of incomplete information on the impacts from 

routine activities under a proposed action on marine mammals, there is credible scientific 

information, applied using acceptable scientific methodologies, to support the conclusion that any 

realized impacts would be sublethal in nature and not in themselves rise to the level of reasonably 

foreseeable significant adverse (population-level) impacts. Also, routine activities would be ongoing 

in the proposed action area as a result of active leases and related activities. There are no data to 

suggest that routine activities from the previous OCS Program are significantly impacting marine 

mammal populations. The net result of any disturbance would depend upon the size and 

percentage of the population likely to be affected, the ecological importance of the disturbed area, 

the environmental and biological parameters that influence an animal’s sensitivity to disturbance and 

stress, or the accommodation time in response to prolonged disturbance (Geraci and St. Aubin, 

1980). Accidental events that involve large spills, particularly those continuing to flow fresh 
Description of the Affected Environment and Impact Analysis 4-307

hydrocarbons into oceanic and/or outer shelf waters for extended periods (i.e., days, weeks, or 

months), pose an increased likelihood of impacting marine mammal populations inhabiting these 

waters.

The effects of a proposed action, when viewed in light of the impacts associated with other 

past, present, and reasonably foreseeable future activities, may result in greater impacts to marine 

mammals than before the Deepwater Horizon explosion, oil spill, and response; however, the 

magnitude of those impacts cannot yet be determined. Nonetheless, operators are required to 

follow all applicable lease stipulations and regulations, as clarified by NTLs, to minimize these 

potential interactions and impacts. The operator’s reaffirmed compliance with NTL 2016-BOEM-G01 

(“Vessel Strike Avoidance and Injured/Dead Protected Species Reporting”) and NTL 2015-

BSEE-G03 (“Marine Trash and Debris Awareness and Elimination”), as well as the limited scope, 

timing, and geographic location of a proposed lease sale, would result in negligible impacts from the 

proposed activities on marine mammals. In addition, NTL 2012-JOINT-G02, “Implementation of 

Seismic Survey Mitigation Measures and Protected Species Observer Program,” minimizes the 

potential for injury from seismic operations to marine mammals. These mitigations include onboard 

observers, airgun shut-downs for whales in the exclusion zone, ramp-up procedures, and the use of 

a minimum sound source. The Protected Species Stipulation, if applied, requires compliance with 

any terms and conditions from past and future biological opinions from NMFS and FWS.

Cumulative impacts on marine mammals are expected to result in a number of chronic and 

sporadic sublethal impacts (i.e., behavioral effects and nonfatal exposure to or intake of OCS 

oil- and gas-related or non-OCS oil- and gas-related contaminants or discarded debris) that may 

stress and/or weaken individuals of a local group or population and predispose them to infection 

from natural or anthropogenic sources (Harvey and Dahlheim, 1994). Disturbance (i.e., noise from 

vessel traffic and drilling operations) and/or exposure to sublethal levels of toxins and anthropogenic 

contaminants may stress animals, weaken their immune systems, and make them more vulnerable 

to parasites and diseases that normally would not be fatal (Harvey and Dahlheim, 1994). There is 

potential for impacts from routine activities or accidental events to be greater on individuals or 

populations already impacted by other OCS oil- and gas-related or non-OCS oil- and gas-related 

impact-producing factors. However, within the GOM, there is a long-standing and well-developed 

OCS Program (more than 50 years) and there are no data to suggest that activities from the 

previous OCS Program are significantly impacting marine mammal populations.

The incremental contribution of a proposed lease sale (Alternative A, B, C, or D) to 

cumulative impacts to marine mammal populations, depending upon the affected species and their 

respective population estimate, even when taking into consideration the potential impacts of the 

Deepwater Horizon explosion, oil spill, and response; non-OCS oil- or gas-related factors; and the 

minimization of OCS oil- or gas-related impacts through lease stipulations and regulations, would be 

expected to be negligible as a result of a proposed action (Alternative A, B, C, or D) and the period 

analyzed.
4-308 Gulf of Mexico Multisale EIS

4.9.1.2.6 Alternative E—No Action

If selected, Alternative E would not contribute to impacts on marine mammal species within 

the GOM. However, cumulatively, the impacts resulting from the routine activities and accidental 

events and the cumulative impacts from previously permitted activities and prior lease sales would 

continue and be unchanged from the conclusion reached for the action alternatives because of 

existing oil and gas activities. Therefore, the significance of impact-producing factors on marine 

mammals would be the same for Alternative E as the impacts discussed in Chapter 4.9.1.2 for 

previously permitted activities and prior lease sales.

4.9.2 Sea Turtles

Five species of sea turtles are known to inhabit the GOM (Pritchard, 1997): green (Chelonia 

mydas); hawksbill (Eretmochelys imbricata); Kemp’s ridley (Lepidochelys kempii); leatherback 

(Dermochelys coriacea); and loggerhead (Caretta caretta). All five species are highly migratory with 

individuals migrating into nearshore waters as well as other areas of the GOM, North Atlantic Ocean, 

and the Caribbean Sea, and all five species use beaches along the coasts during nesting season. 

These sea turtles are protected under the Endangered Species Act of 1973. The FWS and NMFS 

share Federal jurisdiction for sea turtles. The FWS has responsibility for monitoring and managing 

sea turtles (i.e., nesting turtles, eggs, and hatchlings) on the beaches, and NMFS has jurisdiction for 

sea turtles in the marine environment. Refer to Chapter 4.9 above for general information regarding 

protected species. The approach of this analysis is to focus on the potential impact-producing 

factors for sea turtles from OCS oil- and gas-related routine activities (i.e., exploration, development, 

and production), as well as reasonably foreseeable accidental events and cumulative impacts, and 

to define impact-level measures for each impact-producing factor under a proposed action (refer to 

Table 4-18 in Chapter 4.9).

4.9.2.1 Description of the Affected Environment

General information relevant to all five species is discussed in the introduction for 

Chapter 4.9. Species-specific information regarding mating/nesting, foraging, habitat use, 

conservation status, and threats is discussed in the chapters below.

In 2009, NMFS completed a status review of loggerhead sea turtles, and on September 22, 

2011, and issued a final rule to list nine Distinct Population Segments (DPSs) of loggerhead sea 

turtles under the ESA and designated the GOM population under the Northwest Atlantic Ocean DPS 

(Federal Register, 2011b). The Kemp’s ridley 5-year review was completed in July 2015 and the 

status remains unchanged (USDOC, NMFS and USDOI, FWS, 2015). In 2016, NMFS and FWS 

completed a status review of green sea turtles, designating the status of 11 DPSs across the 

species global distribution. The Gulf of Mexico population is included in the designated North 

Atlantic DPS and is considered threatened (Federal Register, 2016f). In 2013, the 5-year reviews for 

leatherback and hawksbill sea turtles were updated and all retained endangered status (USDOC, 

NMFS and USDOI, FWS, 2013a and 2013b).
Description of the Affected Environment and Impact Analysis 4-309

Nesting on the U.S. Gulf Coast has been documented for the five species of sea turtles. 

Loggerheads and Kemp’s ridleys are the most common, followed by green sea turtles, and finally 

leatherback and hawksbill sea turtles; however, the latter two species rarely nest in the GOM 

(USDOC, NMFS and USDOI, FWS, 2007a-c, 2013a, and 2013b). Data can be found for sea turtle 

nesting through different websites, including the National Park Service who has data for Texas 

(USDOI, NPS, 2016), Alabama’s Sea Turtle Conservation Program (Share the Beach, 2015), and 

the State of Florida, Fish and Wildlife Conservation Commission’s websites (State of Florida, Fish 

and Wildlife Conservation Commission, 2016d).

Sea turtles are protected by the Endangered Species Act due to their low population 

numbers and habitat loss. Existing threats to sea turtles include both natural and human-influenced 

impacts that are discussed under the individual species descriptions. Natural phenomena, such as 

tropical storms and hurricanes, occur in the GOM and may impact nesting beaches (Dewald and 

Pike, 2013), depending on timing, size, and location of the storm. Storm impacts to nesting activity 

can be difficult to assess, but beach erosion has been shown to be one of the major factors affecting 

turtle hatchling success (Brost et al., 2015). Although the use of turtle excluding devices has 

reduced interactions, fisheries’ impacts remain the greatest threat to sea turtles (Lewison et al., 

2013).

Sea turtle strandings can be used as an index of their habitat conditions; an increase in 

strandings indicates a change that negatively impacts sea turtles resulting in impairment or mortality 

as identified by recovered stranded turtles or may also be reflective of increased surveillance or 

detection of stranded turtles. Sea turtle strandings along the Gulf and Atlantic Coasts are 

documented and monitored by the Sea Turtle Stranding and Salvage Network and includes Federal, 

State, and private partners. The NMFS provides stranding data for the GOM (i.e., Texas, Louisiana, 

Mississippi, and Alabama) through its Office of Protected Resources site. These data are updated 

regularly when NMFS obtains the data from the Sea Turtle Stranding and Salvage Network 

members. Because this information is routinely updated and can change at any time, BOEM refers 

the reader to NMFS’s website for the most current information (USDOC, NMFS, 2015g). Florida is 

not included in NMFS’ Gulf of Mexico stranding data; however, Florida-specific stranding information 

can be found on the State of Florida, Fish and Wildlife Conservation Commission’s Florida Sea 

Turtle Stranding and Salvage Network website (State of Florida, Fish and Wildlife Conservation 

Commission, 2016e). Stranding data are not indicative of population status because there are many 

variables associated with the data (Epperly et al., 1996; Nero et al., 2013). Stranding data indicate 

the presence of species, which is important particularly regarding populations or species thata are 

rare or uncommon.

Green Sea Turtle (Chelonia mydas) 

Federal listing of the green sea turtle occurred on July 28, 1978 (Federal Register, 1978a). 

All green sea turtle populations are listed as threatened except for the breeding populations of 

Florida and the Pacific Coast of Mexico, which are endangered. The NMFS and FWS finalized a 

rule (Federal Register, 2016f) to remove the current range-wide listing for green sea turtles, to 
4-310 Gulf of Mexico Multisale EIS

replace it with eight DPSs as threatened and three as endangered, and to include application of 

existing protective regulations to the DPSs. Green sea turtles that use the GOM are designated as 

part of the threatened North Atlantic DPS (Federal Register, 2016f).

Green sea turtle mating occurs in the waters off the nesting beaches, and nesting is typically 

associated with the female’s hatching beach. In a study conducted off the coast of southern Florida, 

each female deposited up to six clutches during the breeding season at 9- to 18-day intervals (Hart 

et al., 2013a). Mean clutch size is highly variable among populations but averages about 110 eggs. 

The complete nesting range of the green sea turtle includes sandy beaches of mainland shores and 

barrier islands between Texas and North Carolina and at the U.S. Virgin Islands and Puerto Rico 

(USDOC, NMFS and USDOI, FWS, 1991). Principal U.S. nesting areas for green sea turtles are in 

eastern Florida (Ehrhart and Witherington, 1992).

After hatching, green sea turtles go through a post-hatchling pelagic stage where they move 

offshore and are associated with drift lines of algae, Sargassum, and other debris. The posthatchlings are believed to remain tightly associated with these drift lines for several years, feeding 

close to the surface on a variety of pelagic plants and animals. The post-hatchling, pelagic-stage 

individuals are assumed to be omnivorous, but little data are available. Once the juveniles reach a 

certain age/size range, they leave the pelagic habitat and travel to nearshore foraging grounds. 

Once they move to these nearshore benthic habitats, adult green turtles are almost exclusively 

herbivores, feeding on seagrass and algae. Age at sexual maturity is estimated to be between 

20 and 40 years (USDOC, NMFS and USDOI, FWS, 2007c). Adult females migrate from foraging 

areas to mainland or island nesting beaches and may travel hundreds or thousands of kilometers 

each way (USDOC, NMFS and USDOI, FWS, 2007c).

Foraging areas along the northern GOM include shallow, coastal waters with sufficient 

benthic vegetation such as seagrass. Direct destruction or degredation of these areas from bottom 

disturbance due to dredging, boat anchorage, deposition of spoil, and siltation (Coston-Clements 

and Hoss, 1983; Williams, 1988) influence the distribution of foraging green sea turtles. 

Eutrophication, heavy metals, radioactive elements, and hydrocarbons all may reduce the extent, 

quality, and productivity of foraging grounds (Frazier, 1980; USDOC, NMFS and USDOI, FWS, 

2007c).

The principal cause of past declines and extirpations of green sea turtle assemblages has 

been the over exploitation of eggs and meat. Significant threats on green sea turtle nesting in the 

region include beach armoring and erosion control, artificial lighting, and general disturbance from 

human activity, such as trampling. Armoring of beaches (e.g., seawalls, revetments, rip-rap, 

sandbags, and sand fences) in Florida for protecting developed property by reducing coastal erosion 

is increasing and has been shown to deter nesting, even when armoring structures do not 

completely block access to nesting habitat (Mosier, 1998). Marine debris is a threat to the pelagic 

habitat of juvenile green sea turtles as well, and older juvenile green turtles have been found dead 

after ingesting seaborne plastics (Balazs, 1985). Another issue regarding manmade debris in the 
Description of the Affected Environment and Impact Analysis 4-311

marine or coastal environment is entanglement of turtles in discarded monofilament fishing line and 

abandoned netting (Balazs, 1985).

Ongoing threats to green sea turtles include the occurrence of green sea turtle 

fibropapillomatosis disease, which was originally reported in the 1930’s (Smith and Coates, 1938). 

This disease is globally widespread and has been found to affect large numbers of animals in some 

areas, including Hawaii and Florida (Herbst, 1994; Jacobson, 1990; Jacobson et al., 1991). Gillnets, 

trawl nets, pound nets (Crouse, 1982; Hillestad et al., 1982; NRC, 1990), and any abandoned nets 

(Balazs, 1985; Ehrhart et al., 1990) are known to kill sea turtles as bycatch. To address interactions 

between marine turtles and trawl fishing gear, NOAA worked cooperatively with the commercial 

shrimp trawl industry to develop sea turtle excluder devices (Federal Register, 2015g). Green sea 

turtles are also threatened and taken by hook-and-line fishing. Collisions with power boats and 

encounters with suction dredges have resulted in the mortality of green sea turtles along the U.S. 

coast and may be common elsewhere where boating and dredging activities are frequent.

Hawksbill Sea Turtle (Eretmochelys imbricata) 

The hawksbill sea turtle was listed as endangered on December 2, 1970 (Federal Register, 

1970b). They were once abundant in tropical and subtropical regions and are highly migratory, 

using a wide range of habitats during their lifetime. In the continental U.S., hawksbills have been 

documented along the east coast as far north as Massachusetts and in all Gulf Coast States, but 

they are found primarily along Florida and Texas.

Reproductive females undertake periodic (usually non-annual) migrations to their natal 

beach to nest. Movements of reproductive males are less well known, but they are presumed to 

involve migrations to the nesting beach or to courtship stations along the migratory corridor. 

Immature hawksbills tagged at St. Thomas during long-term, in-water studies appeared to be 

resident for extended periods (Boulon, 1994). Tag returns were recorded from St. Lucia, the British 

Virgin Islands, Puerto Rico, U.S. Virgin Islands, and the Dominican Republic (Boulon, 1989; Meylan, 

1999; USDOC, NFMS and USDOI, FWS, 2013b). While nesting occurs along the beaches 

throughout the world’s oceans with the most nesting occurring on beaches of the Caribbean Sea; 

hawksbill nesting on northern GOM beaches, including Florida, is rare (Mays and Shaver, 1998; 

USDOI, FWS, 2015f). The Atlantic Coast of Florida is the only area in the U.S. where hawksbills 

nest on a regular basis, but the maximum number of nests documented in any year during 

1979-2000 was only four. Females nest an average of 3-5 times per season, and the mean clutch 

size is 130 eggs (USDOC, NMFS and USDOI, FWS, 2013b). 

The life history of hawksbills consists of a pelagic stage that lasts from the time they leave 

the nesting beach as hatchlings until they are approximately 7-12 in (20-30 cm) in straight carapace 

length (Meylan, 1988; Bell and Pike, 2012), followed by residency in developmental habitats 

(foraging areas where immature individuals reside and grow) in coastal waters. As with most sea 

turtle species, hatchlings and early juveniles are often found in association with oceanic Sargassum
4-312 Gulf of Mexico Multisale EIS

floats. As older juveniles, they move nearshore for feeding habitat and may associate with the same 

feeding locality for more than a decade (Musick and Limpus, 1997).

Adult foraging habitat, which may or may not overlap with developmental habitat, is typically 

coral reefs, although other hard bottom communities and occasionally mangrove-fringed bays may 

be occupied. Hawksbills show fidelity to their foraging areas over periods of time as great as several 

years (van Dam and Diez, 1998). The diet is highly specialized and consists primarily of sponges 

and macroalgae, although other food items have been documented to be important in some areas of 

the Caribbean (USDOC, NMFS and USDOI, FWS, 2013b). The lack of sponge-covered reefs and 

the cold winters in the northern GOM may prevent hawksbills from establishing a strong population 

in this area.

The majority of hawksbill sightings are reported from the Sea Turtle Stranding Network. 

Hawksbills undertake developmental migrations (movements as immature turtles) and reproductive 

migrations over long distances (Meylan, 1999).

The primary cause of hawksbill decline has been attributed to historical overexploitation for

tortoise shell, the patterned scales that cover the turtle’s shell (Parsons, 1972; Mortimer and 

Donnelly, 2008). International trade in tortoiseshell is now prohibited among all signatories of the 

Convention on International Trade in Endangered Species (CITES); however, some illegal trade 

continues.

In addition to the factors threatening all marine turtles (described in the sea turtle introduction 

above), hybridization with other species has also been identified as a concern for maintaining the 

genetic integrity of hawksbills (USDOC, NMFS and USDOI, FWS, 2013b). Hybridization occurs 

more often for small populations with low densities as the chance of finding a mate is reduced. 

Globally, the decline of hawksbills has been influenced by impacts to foraging areas and nesting 

beaches by climate change and fisheries bycatch (USDOC, NMFS and USDOI, FWS, 2013b).

Kemp’s Ridley Sea Turtle (Lepidochelys kempii) 

The Kemp’s ridley sea turtle was listed as endangered on December 2, 1970 (Federal 

Register, 1970b). On September 22, 2011, a final bi-national (Mexico and U.S.) recovery plan for 

Kemp’s ridleys was released. The 5-year review for Kemp’s ridleys was released on August 21, 

2015, and the classification did not change. This species was given higher recovery priority from 

NMFS due to the potential for future extinction, while priority from FWS remained the same 

(USDOC, NMFS and USDOI, FWS, 2015). Internationally, the Kemp’s ridley sea turtle is considered 

the most endangered sea turtle throughout its range.

The Kemp’s ridley turtle has a more restricted distribution through all of its life stages relative 

to other sea turtle species. Data suggest that Kemp’s ridley turtles are found mainly in coastal areas 

of the GOM and northwestern Atlantic Ocean; sea-water temperature influences the distribution of 

this species as this species is not tolerant to cold waters (Ogren, 1989; Renaud, 1995; Renaud and 
Description of the Affected Environment and Impact Analysis 4-313

Williams, 2005). The nearshore waters of the GOM are believed to provide important developmental 

habitat for juvenile Kemp’s ridley and loggerhead sea turtles. Ogren (1989) suggested that the Gulf 

Coast, from Port Aransas, Texas, through Cedar Key, Florida, represents the primary habitat for 

subadult Kemp’s ridleys in the northern GOM. Juvenile/subadult Kemp’s ridleys have been found 

along the Eastern Seaboard of the U.S. (Epperly et al., 2007) and in the GOM. Atlantic 

juveniles/subadults travel northward with spring warming to feed in the productive, coastal waters of 

Georgia through New England, returning southward with the onset of winter to escape the cold 

(Ogren, 1989; USDOC, NMFS and USDOI, FWS, 2015). Along the coast of Louisiana, immature 

Kemp’s ridleys migrated to warmer nearshore waters during winter months (Coleman et al., 2016).

Kemp’s ridleys nest in daytime aggregations, arribada, from April to July primarily at Rancho 

Nuevo, a stretch of beach in Mexico, Tamaulipas State (USDOC, NMFS and USDOI, FWS, 2015). 

Remigration of females to the nesting beach varies from annually to every 4 years, with a mean of 

2 years (Turtle Expert Working Group, 1998). The mean clutch size for Kemp’s ridley turgles is 100 

eggs per nest, with an average of 2.5 nests per female per season. According to the 2011 

bi-national recovery plan, nests in and surrounding Rancho Nuevo exceeded 20,000, thereby 

representing 8,000 females for 2009 (Secretariat of Environment & Natural Resources et al., 2011). 

Kemp’s ridley sea turtle nests have increased in recent years along the South Padre Island National 

Seashore in Texas (USDOI, NPS, 2016).

In the GOM, juvenile/subadult Kemp’s ridleys occupy shallow, coastal regions. Little is 

known of the movements of the post-hatching, planktonic stage within the GOM, although model 

predictions suggest that they mostly remain in waters offshore of Tamaulipas, Mexico (Putman et al, 

2013). Studies have shown the post-hatchling pelagic stage varies from 1 to 4 years, and the 

benthic immature stage lasts 7-9 years (Schmid and Witzell, 1997). Benthic immature turtles with an 

8- to 24-in (20- to 60-cm) straight-line carapace length are found in nearshore coastal waters, 

including the estuaries of the GOM and Atlantic, although adult-sized individuals sometimes are 

found on the eastern seaboard of the U.S.

The post-pelagic stages are commonly found dwelling over crab-rich sandy or muddy 

bottoms. Juveniles frequent bays, coastal lagoons, and river mouths. Adults of this species are 

usually confined to the GOM but occasionally swim into the Atlantic along the east coast of the U.S. 

The Turtle Expert Working Group (1998) estimated the age at sexual maturity to be 7-15 years.

Pelagic-stage, neonatal Kemp’s ridleys presumably feed on the available Sargassum and 

associated infauna or other epipelagic species found in the GOM (USDOI, FWS, 2015g). Shaver 

et al. (2013) described the Kemp’s ridley turtle nearshore foraging habitat “hotspots” in the northern 

GOM and, in another study, rehabilitated juveniles that were released showed similar foraging areas 

in coastal areas of Louisiana and Florida (Lyn et al., 2012). Stomach contents of Kemp’s ridley 

turtles along the lower Texas coast consisted of a predominance of nearshore crabs and mollusks, 

as well as fish, shrimp, and other foods considered to be shrimp fishery discards (Shaver, 1991).
4-314 Gulf of Mexico Multisale EIS

Of the five species in the GOM, the Kemp’s ridley has suffered the greatest population 

decline; and historically, that decline was caused by commercial and local exploitation. Many natural 

and anthropogenic threats to the future of the species remain, including interactions with fisheries

gear, dredging, marine pollution, foraging habitat destruction, entrainment in power plant cooling 

system intake structures, illegal poaching of nests, water temperature changes, and threats to 

nesting beaches from such sources as rising sea levels and coastal development (USDOC, NMFS 

and USDOI, FWS 2015).

Leatherback Sea Turtle (Dermochelys coriacea) 

The leatherback sea turtle was listed as endangered on December 2, 1970 (Federal 

Register, 1970b). The leatherback is the largest and most pelagic of sea turtles. The average 

curved carapace length for adults is 61 in (155 cm) and weights from global populations range from 

441 to 1,543 lb (200 to 700 kg).

Leatherback distribution and nesting grounds are found around the world in waters of the 

Atlantic, Pacific, and Indian Oceans; the Caribbean Sea; and the Gulf of Mexico (Ernst et al., 1994; 

USDOC, NMFS and USDOI, FWS 2013a). The leatherback is the most abundant sea turtle in 

waters over the northern GOM continental slope (Mullin and Hoggard, 2000). Leatherbacks appear 

to use continental shelf and slope habitats in the GOM (Collard and Ogren, 1990; Davis and Fargion, 

1996). Surveys indicate that the region from Mississippi Canyon to De Soto Canyon, especially near 

the shelf edge, appears to be an important habitat for leatherbacks in the northern GOM (Mullin and 

Hoggard, 2000). Leatherbacks have been frequently sighted in the GOM during summer and winter 

(Mullin and Hoggard, 2000). Stranding data from 1986 through 2016, as reported by NOAA’s Sea 

Turtle Stranding Network, indicated leatherback strandings in all states within the northern GOM. 

The current estimate of the northern Atlantic population, which includes the GOM, is 

34,000-94,000 adults (USDOC, NMFS and USDOI, FWS, 2013a). Leatherbacks are a long-lived 

species (>30 years), with an estimated age of sexual maturity reported at about 3-19 years (Zug and 

Parham, 1996).

Historically, the largest concentrations of nesting females were found along the Pacific Coast 

of Mexico, but this population has been declining (Pritchard, 1982; Sarti et al., 1996). Also 

associated with the Pacific, nesting has been reported from China, Southeast Asia, Indonesia, and 

Australia. In the western Atlantic, female leatherbacks nest from the southeastern U.S. (east coast 

of Florida) to southern Brazil and from Mauritania to Angola in the eastern Atlantic Ocean (USDOC, 

NMFS and USDOI, FWS, 2013a; USDOI, FWS, 2015h). They nest frequently with up to 7 nests per 

year during a nesting season (March-July) and nest about every 2-3 years, although nesting is rare 

on GOM beaches (State of Florida, Fish and Wildlife Conservation Commission, 2016d). During 

each nesting, females may produce 100 eggs or more in each clutch (Schultz, 1975); however, 

leatherback clutches recorded at Buck Island, U.S. Virgin Islands, in 2014 ranged from 48 to 

72 (Pollock et al., 2015). The eggs require approximately 60 days of incubation.
Description of the Affected Environment and Impact Analysis 4-315

Once the hatchlings emerge from the nest and leave the natal beach, very little is known 

about the juvenile life stage. While other species of sea turtle remain in pelagic waters and 

Sargassum, there are no records to indicate this is consistent with leatherbacks. So little is known 

about the early life history of leatherbacks that the period from hatching to approximately 10 years 

later, when females return to the nesting beach, is referred to as the “lost years” (Carr, 1986). 

Although some studies have used stable isotopes to help determine approximate distributions of

other sea turtle species during this lifestage (Reich et al., 2007), the data are still short term and 

would require advanced technologies to better track hatchling turtles. Given that information on the 

“lost years” of hatchling to 10-year-old leatherbacks would inform better management decisions, 

research has been continuing to gain a better understanding of this lifestage. BOEM has 

determined that the incomplete or unavailable information is not essential to a reasoned choice 

among alternatives; the best available science has been used to evaluate the potential impacts of a 

proposed action and its alternatives.

Adult leatherbacks forage in temperate and subpolar regions from 71° N. to 47° S. latitude in 

all oceans and undergo extensive migrations between 90° N. and 20° S. latitude to and from the 

tropical nesting beaches (USDOC, NMFS and USDOI, FWS 2013a). The leatherback forages 

widely throughout the water column from the surface to great depths throughout tropical and 

temperate oceans of the world. The distribution of leatherbacks appears to be dependent upon the 

distribution of their prey (Leary, 1957), consisting mostly of jellyfish and other pelagic gelatinous 

organisms, such as tunicates. Adults have been tracked foraging in the GOM on the cannonball 

jellies, Stomolophus sp. and moon jellies, Aurelia sp. (Evans, 2006; Lohoefener et al., 1988). Adult 

leatherbacks are deep divers, with estimated dives to depths in excess of 3,281 ft (1,000 m) (Eckert 

et al., 1989), but they may come into shallow waters if there is an abundance of jellyfish nearshore.

Ongoing threats to leatherbacks include ingestion of marine debris (Shoop and Kenney, 

1992; Bugoni et al., 2001; Mrosovsky et al., 2009), poaching of eggs and animals (Boulon, 2000), 

entanglement in longline fishing gear (USDOC, NMFS, 2001), coastal trawl, and net and longline 

fisheries (Marcano and Alio-M., 2000; USDOC, NMFS, 2007b). Leatherback sea turtles seem to be 

the most susceptible to entanglement. This susceptibility may be the result of attraction to 

gelatinous organisms and algae that collect on buoys and buoy lines at or near the surface, and 

perhaps to the lightsticks used to attract target species in the longline fishery. According to observer 

records, an estimated 6,363 leatherback sea turtles were caught by the U.S. Atlantic tuna and 

swordfish longline fisheries between 1992 and 1999, of which 88 were discarded dead (USDOC, 

NMFS, 2001). Since then, U.S. pelagic longline fisheries in the Atlantic have incorporated 

mandatory bycatch reduction measures (USDOC, NMFS and USDOI, FWS, 2013a). However, 

Atlantic (including the Mediterranean, which has much higher fishing effort) longline sea turtle 

bycatch rates are higher than Pacific bycatch (Lewison et al., 2004). Reports of incidental takes of 

leatherback turtles are incomplete for many nations, including and in particular, the GOM (USDOC, 

NMFS, 2001).
4-316 Gulf of Mexico Multisale EIS

Loggerhead Sea Turtle (Caretta caretta) 

The loggerhead sea turtle was listed as threatened on July 28, 1978 (Federal Register, 

1978a). It is still considered threatened under the reclassification as the Northwest Atlantic Ocean 

DPS in the GOM (Federal Register, 2011b).

In the GOM, loggerhead turtles have been primarily sighted in waters above the continental 

shelf, although many surface sightings of this species have also been made above the outer slope 

beyond the 1,000-m (3,281-ft) isobath. Additionally, Van Houtan and Halley (2011) modeled 

oceanographic processes in relation to loggerhead regional population dynamics and found that they 

are strongly correlated; therefore, they should be considered in baseline conditions. Sightings of 

loggerheads in waters above the continental slope suggest that they may be in transit through these 

waters to distant foraging sites or seeking warmer waters during the winter. Although loggerheads 

are widely distributed during both summer and winter, their presence in surface waters above the 

slope was greater during winter than in summer (Mullin and Hoggard, 2000). Adult loggerheads are 

known to make extensive migrations between foraging areas and nesting beaches. During 

non-nesting years, adult females from U.S. beaches are distributed in waters off the eastern U.S. 

and throughout the Gulf of Mexico, Bahamas, Greater Antilles, and Yucatán (Conant et al., 2009).

Loggerheads mate in late March through early June in the southeastern U.S. The mean 

clutch size for loggerheads is 100-126 eggs per nest, with an average of 4.1 nests/nesting individual 

per nesting season (USDOC, NMFS, 2013; Murphy and Hopkins, 1984). The nesting migration for 

an individual female loggerhead is usually on an interval of 2-3 years but it can vary from 1 to 

7 years (Dodd, 1988). In the western Atlantic, most loggerhead sea turtles concentrate their nesting 

in the north and south temperate zones and subtropics, and they generally do not nest in the 

geographic area ranging from North Carolina to the Florida Panhandle tropical areas (Magnuson 

et al., 1990; USDOC, NMFS and USDOI, FWS, 2007b). Major nesting areas include the coastal 

islands of Georgia, South Carolina, North Carolina, and Florida’s Atlantic Coasts. In the GOM, major 

nesting areas include some coastal beaches in Mississippi, Alabama, and Florida (Figure 4-25). 

Reproductive adult females return to their original hatching site to nest. Nesting data trends are 

declining in this species (Federal Register, 2011b; Witherington et al., 2009; Lamont et al., 2012). 

Five recovery units have been identified; three that are relevant are Peninsular Florida, Dry 

Tortugas, and the northern GOM. According to Ehrhart et al. (2003), the peninsular Florida 

Recovery Unit represents approximately 87 percent of all nesting effort in the Northwest Atlantic 

Ocean DPS.

Developmental habitat for juveniles is in the open ocean. Offshore, they reside for months in 

the oceanic zone in Sargassum floats, generally along the Loop Current and the west coast of 

Florida. Refer to Chapter 4.5 (Sargassum and Associated Communities) for additional information 

on pelagic waters. Somewhere between 7 and 12 years old, oceanic juveniles migrate to nearshore 

coastal areas to mature into adults. These nearshore waters become important foraging and 

migratory habitat for juveniles and adults. Juveniles may also spend time in bays, sounds, and 

estuaries (Epperly et al., 2007). Benthic immature loggerheads have been found from Cape Cod, 
Description of the Affected Environment and Impact Analysis 4-317

Massachusetts, to southern Texas (USDOC, NMFS and USDOI, FWS, 2007d). Large benthic 

immature loggerheads (28-36 in; 70-91 cm) represent a larger proportion of the strandings and inwater captures along the south and western coasts of Florida as compared with the rest of the coast. 

Benthic immature loggerheads foraging in northeastern U.S. waters are known to migrate southward 

in the fall as water temperatures cool (Epperly et al., 1995; Morreale and Standora, 1999) and 

migrate northward in spring. Juveniles are omnivorous and forage on crabs, mollusks, jellyfish, and 

vegetation at or near the surface (Dodd, 1988). Subadult and adult loggerheads are primarily 

coastal and typically prey on benthic invertebrates such as mollusks and decapod crustaceans in 

hard bottom habitats. McClellan and Read (2007) found that the shift from oceanic to neritic (i.e., 

coastal) waters is complex and reversible; some move into coastal waters and then return to open 

ocean.

Loggerhead sea turtles originating from the western Atlantic nesting aggregations are 

believed to lead a pelagic existence in the North Atlantic gyre for as long as 7-12 years, but there is 

some variation in habitat use by individuals at all life stages. Stranding records indicate that, when 

pelagic immature loggerheads reach a 16- to 24-in (40- to 60-cm) straight-line carapace length, they 

begin to recruit to coastal inshore and nearshore waters of the continental shelf throughout the U.S. 

Atlantic and GOM. Bjorndal et al. (2013) combined datasets over a large spatial scale (range of 

9-33° N. latitude) to examine northwest Atlantic loggerhead growth rates and found that there was a 

decline with increasing body size. Their study indicated that latitude may be a major factor for 

smaller turtles (<2.6 ft; 80 cm) and that loggerheads may grow more rapidly in waters south of the 

U.S., noting that more data are needed for those waters to determine growth rates (Bjorndal et al., 

2013).

Several recent reports are available concerning GOM loggerheads’ nesting habitats and 

movements (Hart et al., 2013b), post-nesting behavior (Foley et al., 2013), foraging sites (Foley 

et al., 2014; Tucker et al., 2014), and body size effects on growth rates (Bjorndal et al., 2013). 

These reports confirm the importance of GOM beaches, specifically for loggerheads. Lamont et al. 

(2015) also published a report on the importance of the GOM for different life stages of the 

Northwest Atlantic Ocean DPS. Lamont et al. (2015) suggested that the loss of any life stage habitat 

could have long-term consequences to population recovery by affecting several life stages. 

Additional relevant information can be found in Chapter 4.3.2 (Coastal Barrier Beaches and 

Associated Dunes).

Ongoing threats to the western Atlantic loggerhead populations include incidental takes from 

dredging, commercial trawling (Epperly et al., 2002), longline fisheries (Lewison et al., 2004), and 

gillnet fisheries; loss or degradation of nesting habitat from storms (Brost et al., 2015) or coastal 

development and beach armoring; disorientation of hatchlings by beachfront lighting; nest predation 

by native and nonnative predators (Brost et al., 2015); degradation of foraging habitat; marine 

pollution and debris; watercraft strikes; and disease (USDOC, NMFS and USDOI, FWS, 2007b).
4-318 Gulf of Mexico Multisale EIS

Critical Habitat

Of all five GOM sea turtles species, the loggerhead is the only sea turtle that has critical 

habitat established in the GOM (Figure 4-25). As described above, NMFS and FWS are jointly 

responsible for managing sea turtles. The NMFS designated marine critical habitats in its Final Rule 

in July 2014, and FWS’ designated terrestrial critical habitat in its Final Rule in August 2014 (Federal 

Register, 2014a and 2014c). The offshore marine critical habitat is Sargassum and the terrestrial 

critical habitat is the nesting beaches (Figure 4-25).

Four of the five species of sea turtles found in the GOM are associated with floating 

Sargassum (Carr, 1987b; Coston-Clements et al., 1991; Schwartz, 1988; Witherington et al., 2012). 

The hatchlings of loggerhead, Kemp’s ridley, green, and hawksbill sea turtles are thought to find the 

Sargassum rafts when actively seeking frontal zones and then utilizing the habitat as foraging 

grounds and protection during their pelagic “lost years” (juvenile years in which turtle sightings are 

scarce) (Carr, 1987b; Coston-Clements et al., 1991). Schwartz (1988) reported numerous 

loggerhead hatchlings during commercial trawling for Sargassum in the Atlantic. This provided the 

largest documented count of hatchlings to date. Witherington et al. (2012) conducted a study on 

juvenile turtle use of Sargassum habitats and further supported that these drifting communities are 

important areas for young sea turtles (84% of 1,884 turtles were observed within 1 m [3 ft] of floating 

Sargassum). Sea turtle digestive system samples contained mainly marine animals and plants, 

plastics, wood, and flying insects. Tarballs, oiled plastics, and liquid oil were observed in Sargassum

drift lines during the surveys (Witherington et al., 2012). Putman and Mansfield (2015) reported that 

passive-drifting sea turtle juveniles (Sargassum-associated stage) were actually active swimmers. 

Their research used synchronized surface drifter and tagged turtle releases to support that sea 

turtles in the GOM are able to move independently from and are not dispersed solely by currents 

(Putnam and Mansfield, 2015). Details about Sargassum can be found in Chapter 4.5 (Sargassum 

and Associated Communities).

4.9.2.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from activities described in Chapter 3

and their potential impacts on sea turtles that would potentially result from a single lease sale or the 

alternatives. This analysis applies to all considered alternatives. While a proposed WPA lease sale 

(Alternative C) would be in a smaller area with less projected activity than a proposed regionwide 

(Alternative A) or proposed CPA/EPA lease sale (Alternative B) as described in Chapter 3, sea 

turtles are distributed throughout the planning areas. As such, activities isolated to specific planning 

areas pose similar potential impacts to populations as do activities occurring in all planning areas. 

Therefore, because of the free swimming ability and wide distribution of species across the Area of 

Interest, the level of impacts would be the same for Alternatives A, B, C, and D. However, 

Alternative E, No Action, would avoid impacts from a proposed lease sale and the related postlease 

activities as the lease sale would not be held; only impacts from past lease sales and associated 

postlease activities or other G&G permits would continue. Following this environmental 
Description of the Affected Environment and Impact Analysis 4-319

consequences chapter, there is a summary of the potential impacts as they relate to the other action 

alternatives.

4.9.2.2.1 Routine Activities

Routine activities (described in Chapter 3.1) resulting from a proposed action have the 

potential to harm sea turtles, although this potential is unlikely to rise to a level of significance to the 

population due to the activity already present in the GOM and mitigations that have been historically 

applied and discussed below. The routine activities that could have impact-producing factors 

associated with a proposed action that may affect GOM sea turtles include geological and 

geophysical activities (Chapter 3.1.2.1), transportation (Chapter 3.1.4), discharges and wastes

(Chapter 3.1.5), decommissioning (Chapter 3.1.6), and noise (Chapter 3.1.9). Scenario numbers 

presented in this chapter are for Alternative A, which represents a regionwide lease sale with 

expected lease stipulations for this and other alternative scenario numbers (refer to Table 3-2).

Geological and Geophysical Activities

Seismic operations have the potential to harm sea turtles in close proximity to active airgun 

arrays. The Protected Species Stipulation and NTL 2016-BOEM-G02, “Implementation of Seismic 

Survey Mitigation Measures and Protected Species Observer Program,” minimize the potential of 

harm from seismic operations to sea turtles that could be within the exclusion zone. These 

mitigations for sea turtles and marine mammals include, but are not limited to, onboard observers, 

ramp-up procedures, and the use of a minimum sound source. Noise impacts on turtles from 

seismic surveys are described in the “Noise” section below.

Further detailed information on seismic surveys and other G&G survey types may be found 

in Chapter 3.1.2.1. More information on sea turtle hearing and sensitivity to acoustic impacts can be 

found in Appendix I of BOEM’s Atlantic OCS Proposed Geological and Geophysical Activities: MidAtlantic and South Atlantic Planning Areas, Final Programmatic Environmental Impact Statement, 

(USDOI, BOEM, 2014a) and Appendix H of the Geological and Geophysical Exploration for Mineral 

Resources on the Gulf of Mexico Outer Continental Shelf: Final Programmatic Environmental 

Assessment, (USDOI, MMS, 2004b). As of this Multisale EIS, BOEM, with BSEE and NMFS as 

cooperating agencies, prepared the Gulf of Mexico G&G Programmatic EIS to evaluate the potential 

environmental impacts of multiple G&G activities within Federal waters of the Gulf of Mexico’s OCS 

and adjacent State waters, and is currently in the process of evaluating public comments. This Gulf 

of Mexico G&G Programmatic EIS evaluates all G&G activities in the GOM (for oil and gas, marine 

minerals, and renewable activities) over a 10-year period, including a small subset of reasonably 

foreseeable postlease G&G activities that may occur as a result of a proposed lease sale being 

evaluated in this Multisale EIS.

Noise associated with G&G activities may cause behavioral effects (changes in direction or 

swimming speed) or auditory masking in sea turtles. Based on current information on sea turtle 

hearing capabilities, it is not clear whether or not sea turtles rely on sound or would be affected by 

auditory masking (Popper et al., 2014). For more on noise impacts, refer to the “Noise” section 
4-320 Gulf of Mexico Multisale EIS

below. In addition, NMFS, BOEM, and BSEE collaborated to publish National Standards for a 

Protected Species Observer Program to reduce impacts to protected species from G&G activities by 

standardizing the variation in and improving the management of the program (Baker et al., 2013).

The only other impact-producing factor to sea turtles that is associated with G&G activities is 

the potential for gear interaction. Sea turtles can become entangled in some types of lines 

associated with G&G activities, which has occurred in the past with ocean bottom cable/ocean 

bottom node surveys and other activities where rope tethers were used (e.g., anchors, buoys). The 

deployment of nodes and cables is conducted by a remotely operated vehicle by dropping nodes on 

a tether, or by laying cables off the back of a layout boat. The G&G permit applications are reviewed 

by BOEM and NMFS to set conditions of approval with each activity that minimizes impacts caused 

by gear interactions, which are expected to be rare. With the implementation of mitigations, impacts 

from G&G activities would be expected to be negligible to moderate. Moderate impacts may occur 

if a sea turtle has a negative interaction with gear, leading to injury that is irreversible and does not 

impact the species at a population level.

Transportation

An estimated 29,000-270,000 (highest range under Alternative A) service-vessel roundtrips 

are expected to occur annually as a result of a proposed action. Transportation corridors would be 

through areas where sea turtles have been sighted. Helicopter operation round trips are expected to 

be 87,000-1,928,000 as a result of a proposed action. Noise from service-vessel traffic and 

helicopter overflights may elicit a startle response from sea turtles, and there is the possibility of 

short-term disruption of activity patterns. For noise impacts related to OCS vessel and air traffic 

activities, refer to the “Noise” section below. Other impacts related to transportation are described in 

this section.

Vessel strikes are impact-producing factors associated with transportation associated with a 

proposed action that could affect sea turtles. Sea turtles spend at least 3-6 percent of their time at 

the surface for respiration and perhaps as much as 26 percent of their time at the surface for 

basking, feeding, orientation, and mating (Lutcavage et al., 1997). Data show that collisions with all 

types of commercial and recreational vessels cause sea turtle mortality in the GOM (Lutcavage 

et al., 1997). Stranding data for the U.S. Gulf and Atlantic Coasts, Puerto Rico, and the U.S. Virgin 

Islands show that, between 1986 and 1993, about 9 percent of living and dead stranded sea turtles 

had boat strike injuries (Lutcavage et al., 1997).

Sea turtles located in shallower waters have shorter surface intervals, whereas turtles 

occurring in deeper waters have longer surface intervals. It is not known whether turtles exposed to 

recurring vessel disturbance would be stressed or otherwise affected in a negative but 

inconspicuous way. Increased vessel traffic would increase the probability of collisions between 

vessels and turtles, potentially resulting in injury or death to some animals.
Description of the Affected Environment and Impact Analysis 4-321

There have been no documented sea turtle strikes with drilling and service vessels in the 

GOM; however, collisions with small or submerged sea turtles may go undetected. Based on sea 

turtle density estimates in the GOM, the encounter rates between sea turtles and vessels would be 

expected to be greater in water depths <200 m (656 ft) (USDOC, NMFS, 2007a). To further 

minimize the potential for vessel strikes, NTL 2016-BOEM-G01 was issued; this NTL provides 

NMFS’ guidelines for monitoring procedures related to vessel strike avoidance measures for sea 

turtles and other protected species. Historically, compliance with this NTL and other protective 

measures has been mandatory as a result of the Protected Species Stipulation, which has been 

applied at the lease sale stage. With the implementation of these measures and the avoidance of 

potential strikes from OCS vessels, the risk of collisions between oil- and gas-related vessels 

(including those for G&G, drilling, production, decommissioning, and transport) and sea turtles is 

appreciably reduced, but strikes may still occur. BOEM and BSEE monitor for any takes that have 

occurred as a result of vessel strikes and require that any operator immediately report the striking of 

any animal (NTL 2016-BOEM-G01). Given the scope and timing of a proposed action, the transitory 

nature of sea turtles, as well as the established mitigation described above, the impacts to sea 

turtles from vessel collisions are expected to be negligible; however, if by chance collisions occur 

that are not reasonably forseeable, impacts could be moderate, causing impacts that are irreversible 

and that do not affect the species at a population level.

Discharges and Wastes

Contaminants in waste discharges and drilling muds might indirectly affect sea turtles

through food-chain biomagnification, but there is uncertainty concerning the possible impacts. Most 

operational discharges are diluted and dispersed when released in offshore areas and are 

considered to have sublethal effects (Kennicutt, 1995; Kennicutt et al., 1996). Any potential impacts 

from drilling fluids or other operational discharges and wastes would be indirect as a result of 

ingestion via the food chain (Neff et al., 1989). Impacts from water degradation are expected to be 

negligible due to rapid dilution of the discharges, which are also regulated by NPDES permits, and 

due to the wide-ranging movements of sea turtle species in the GOM. Refer to Chapter 3.1.5 for 

more information on operational wastes and discharges generated by OCS oil- and gas-related 

facilities and Chapter 4.2 for a discussion of potential water quality impacts as a result of these 

activities.

Decommissioning

Offshore structures serve as artificial reefs and are sometimes used by sea turtles for 

foraging and resting (Gitschlag and Herczeg, 1994). Explosive severance of these structures can 

affect turtles located in the vicinity of the structure during the severance activity. The estimated 

number of platforms to be decommissioned as a result of a selected alternative is reported in 

Chapter 3.1.6. With the highest range under Alternative A, an estimated 9-193 projects of explosive 

severance of structure removals are projected to occur over 50 years (Table 3-2). 

Decommissioning activities, which are approved by BSEE, are described in detail in 

Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf: Programmatic 
4-322 Gulf of Mexico Multisale EIS

Environmental Assessment (USDOI, MMS, 2005), and they are summarized in Chapter 3. The 

NTL, “Decommissioning Guidance for Wells and Platforms” (NTL 2010-G05) provides guidelines for 

offshore operators that specify and reference NMFS’s biological opinion mitigation requirements 

currently in place for protected species, including sea turtles. In addition, terms and conditions, and 

reasonable and prudent measures identified during ESA consultation for decommissioning would be 

required conditions of approval in any decommissioning authorizations. The regulations at 30 CFR 

part 550 outline the environmental, monitoring, and mitigation information that operators must submit 

with plans for exploration, development, and production. This regulation requires OCS energyrelated activities to be conducted in a manner that is consistent with the provisions of the ESA. 

Additionally, NMFS has implemented a protected species observer program for structure 

decommissioning. Actual sea turtle impacts from explosive removals in recent years have been 

small. Though mitigations that are in place would minimize the risk of impacts to sea turtles, there is 

a possibility of sea turtles going undetected within the zone of explosive impacts; therefore, 

explosive severance could moderately impact sea turtles. However, the updated pre- and postdetonation mitigations should ensure that injuries remain extremely rare. With implementation of 

specified decommissioning mitigations, impacts to sea turtles from explosive severance are 

expected to be negligible. 

Noise

Noise-induced stress has not been well-studied in sea turtles. Captive loggerhead and 

Kemp’s ridley turtles exposed to brief audio-frequency vibrations initially showed startle responses of 

slight head retraction and limb extension (Lenhardt et al., 1983). Sound-induced swimming 

response has been observed for captive loggerhead and green sea turtles (O’Hara and Wilcox, 

1990; Moein et al., 1993; Lenhardt, 1994). Loggerhead hearing frequency range is between 50 and 

1100 Hz, depending on the size of the turtle (Lavender et al., 2014). Some loggerheads exposed to 

low-frequency sound responded by swimming towards the surface at the onset of the sound, 

presumably to lessen the effects of the transmissions (Lenhardt, 1994). The potential direct and 

indirect impacts of sound on sea turtles include physical auditory impacts (temporary threshold shift), 

behavioral disruption, long-term impacts, masking, and adverse impacts on the food chain. 

Low-frequency sound transmissions could potentially cause increased surfacing and avoidance from 

the area near the sound source (Lenhardt et al., 1983; O’Hara and Wilcox, 1990; McCauley et al., 

2000). Leatherback hatchlings were shown to detect sounds between 50 and 1,200 Hz underwater 

and 50 and 1,600 Hz in air with maximum sensitivity between 100 and 400 Hz in water and 50 and 

400 Hz in air (Dow Piniak et al., 2012).

For seismic sources, sea turtles have the potential for mortality or injury at or above 210 dB 

cumulative sound exposure level and above 207 dB peak pressure level (Popper et al., 2014). Sea 

turtles have been observed noticeably increasing their swimming in response to an operating 

seismic source at 166 dB in water (McCauley et al., 2000). There is a high potential for recoverable 

injury, temporary threshold shift (recoverable hearing loss), and behavioral modifications only when 

the turtle is in close proximity to the source. Mortality and injury caused by shipping and continuous 

noise are expected to have low levels of relative risk even if a sea turtle is near the source. The risk 
Description of the Affected Environment and Impact Analysis 4-323

for temporary threshold shift near the source is moderate, while the risk for masking may be high 

both at near and intermediate distances from the source, and the risk for behavioral modifications 

near the source are high and moderate at intermediate distances from the source (Popper et al., 

2014). Impacts from any sound source are relative to the source type, distance to the source, 

frequency, intensity and duration of the source, and distance to the animal. Refer to Chapter 3.1.2.1

for more information on noise related to G&G activities.

Reactions to aircraft or vessel noise, such as avoidance behavior, may disrupt normal 

activities, including feeding. Important habitat areas (e.g., feeding, mating, and nesting) may be 

avoided because of noise generated in the vicinity. There is no information regarding the long-term 

consequences that these disturbances may have on sea turtles. There are no systematic studies 

published of the reactions of sea turtles to aircraft overflights; however, anecdotal reports indicate 

that sea turtles often react to the sound and/or the shadow of an aircraft by diving. It is projected 

that 70,000-3,750,000 OCS oil- and gas-related helicopter operations (take-offs and landings) would 

occur in the support of OCS oil- and gas-related activities over the 50-year analysis period 

(Table 3-2). The Federal Aviation Administration’s Advisory Circular 91-36D (September 17, 2004) 

encourages pilots to maintain higher than minimum altitudes over noise-sensitive areas. Vessel 

noise is an impact-producing factor associated with a proposed action that could affect sea turtles. 

The dominant source of noise from vessels is propeller operation (i.e., cavitation), and the intensity 

of this noise is largely related to ship size and speed. Noise from service-vessel traffic may elicit a 

startle reaction from sea turtles and produce a temporary sublethal stress (NRC, 1990). Startle 

reactions may result in increased surfacings, possibly causing an increase in risk of vessel collision. 

Vessel noise from activities resulting from a proposed action would produce low levels of noise, 

generally in the 150- to 170-dB re 1 μPa-m and at frequencies below 1,000 Hz. Vessel noise is 

transitory and generally does not propagate at great distances from the vessel. If sound affects any 

prey species, impacts to sea turtles would depend on the extent that prey availability might be 

altered.

Drilling and production facilities produce an acoustically wide range of sounds at frequencies 

and intensities that could possibly be detected by turtles. Drilling noise from conventional metallegged structures and semisubmersibles is not particularly intense and is strongest at low 

frequencies (Richardson et al., 1995). A few preliminary investigations using adult green, 

loggerhead, and Kemp’s ridley turtles suggest that they are most sensitive to low-frequency sounds 

(Ridgway et al., 1969; Lenhardt et al., 1983; Bartol et al., 1999). It has been suggested that sea 

turtles use acoustic signals from their environment as guideposts during migration and as a cue to 

identify their natal beaches (Lenhardt et al., 1983). Bone-conducted hearing appears to be a 

reception mechanism for at least some of the sea turtle species, with the skull and shell acting as 

receiving structures (Lenhardt et al., 1983). Oil and gas exploration and extraction occur in sea 

turtle foraging habitats and generates high-intensity, low-frequency, impulsive sounds within the 

leatherback hearing range (Dow Piniak et al., 2012).

Chronic sublethal effects (e.g., stress), resulting in persistent physiological or behavioral 

changes and/or avoidance of impacted areas from noise disturbance such as seismic activities, 
4-324 Gulf of Mexico Multisale EIS

could cause declines in survival or fecundity and could result in population declines; however, such 

declines are not expected because of implementation of the Protected Species Stipulation and NTL 

2012-JOINT-G02 minimizing potential harm. Overall noise impacts on sea turtles from a proposed 

action are expected to be negligible to minor depending on the location of the animal(s) relative to 

the sound source and the frequency, intensity, and duration of the source. A minor impact would be 

a behavioral change in response to noise. Refer to Chapter 3.1.9 for more information on potential 

noise impact-producing factors associated with a proposed action.

4.9.2.2.2 Accidental Events

Reasonably foreseeable accidental events as a result of a proposed action have the 

potential to harm sea turtles. The major impact-producing factors resulting from the accidental 

events associated with a proposed action that may affect sea turtles include oil spills and spillresponse activities. These have the potential to impact small to large numbers of sea turtles in the 

GOM, depending on the magnitude and frequency of low-probability accidents, the ability to respond 

to accidents, the location and date of accidents, various meteorological and hydrological factors, and 

life history stages of animals exposed to the hydrocarbons (NRC, 2003; USDOC, NMFS, 2015h).

Oil Spills

Improperly balanced well pressures that result in sudden, uncontrolled releases of fluids from 

a wellhead or wellbore can occur during any phase of development (i.e., exploratory drilling, 

development drilling, production, completion, or workover operations [refer to Chapter 3.2.1 for 

description of development activities]). Though oil and gas exploration overlaps sea turtles habitats, 

it is the particular biology and behavior of sea turtles that place them at risk, including a lack of 

avoidance behavior, indiscriminate feeding in convergence zones, and large pre-dive inhalations 

(Shigenaka et al., 2010). Oil spills, however, are not the foremost danger to sea turtles, as 

described above. Impacts would occur as a result of actual contact with the spilled oil, regardless of 

the source.

All sea turtle species and life stages are vulnerable to the harmful effects of oil through direct 

contact or by fouling of their habitats and prey. Sea turtles accidentally exposed to oil or tarballs 

may suffer inflammatory dermatitis, ventilatory disturbance, salt gland dysfunction or failure, red 

blood cell disturbances, immune responses, and digestive disorders or blockages (Vargo et al., 

1986; Lutz and Lutcavage, 1989; Lutcavage et al., 1995). Significant changes in blood chemistry 

following contact with hydrocarbons have been reported ranging from changes to blood’s oxygen 

transport system to elevation in white blood cells, indicating stress (Lutcavage et al., 1995). 

Although disturbances may be temporary, long-term impacts remain unknown, and chronically 

ingested oil may accumulate in organs. Oil can adhere to the body surface of sea turtles. Oil has 

been observed to cling to the nares, eyes, and upper esophagus (Overton et al., 1983; Van Vleet 

and Pauly, 1987; Gramentz, 1988; Lutcavage et al., 1995). Witham (1983) found tar sealed the 

mouth and nostrils of small turtles. Periocular tissues and other mucous membranes would 

presumably be most sensitive to contact with hydrocarbons. Turtles may become entrapped by tar 

and oil slicks and rendered immobile (Witham, 1978; Plotkin and Amos, 1988; Gramentz, 1988). All 
Description of the Affected Environment and Impact Analysis 4-325

structural and biochemical changes in the epidermis of sea turtles have been shown to be minor and 

reversible. A break in the skin barrier could act as a portal of entry for pathogenic organisms, 

leading to infection, neoplastic conditions, and debilitation (Vargo et al., 1986).

Contact with hydrocarbons may not cause direct or immediate death but cumulative 

sublethal impacts, such as salt gland disruption or liver impairment, could impair a sea turtle’s ability 

to function effectively in the marine environment (Vargo et al., 1986; Lutz and Lutcavage, 1989; 

Camacho et al., 2012). Although many observed physiological insults are resolved in a 21-day 

recovery period, the impact of tissue oil intake on the long-term health and survival of sea turtles 

remains unknown (Lutcavage et al., 1995). Camacho et al. (2013) conducted blood plasma testing 

on stranded sea turtles to determine PAH concentrations. Burning fossil fuels and urban runoff, as 

well as oil spills, were considered as being potential environmental sources of PAHs detected in 

turtle blood plasma (Camacho et al., 2013). A similar study was conducted by Camacho et al. 

(2014) on live juvenile turtles and it was determined that the turtles had 34 of 52 organic 

contaminants. Contrary to previous data (Geraci and St. Aubin, 1983), PAH biomagnification does 

not occur in sea turtles, suggesting that sea turtles may be able to efficiently metabolize PAHs 

(Camacho et al., 2014).

Eggs, hatchlings, and small juveniles are particularly vulnerable if contacted (Fritts and 

McGehee, 1982; Lutz and Lutcavage, 1989; Bjorndal et al., 1994). Sea turtle hatchling exposure to, 

fouling by, or consumption of tarballs would likely be fatal. Sea turtle eggs are likely to be lethally 

impacted by contact with spilled oil (USDOI, NPS, 2011a). During nesting, a female turtle might 

crawl through tar prior to laying her eggs or might push oil mixed with sand into the nest and 

contaminate the eggs (Chan and Liew, 1988). Assuming a sea turtle’s sense of smell is critical, oil 

fouling of a nesting area might disturb imprinting of hatchling turtles or confuse the turtles on their 

return migration (Geraci and St. Aubin, 1985; Chan and Liew, 1988). Potential toxic impacts to 

embryos would depend on the type of oil and degree of weathering, type of beach substrate, and 

especially upon the developmental stage of the embryo. Embryonic development in an egg may be 

altered or arrested by contact with oil (Fritts and McGehee, 1982). Fresh oil was found to be highly 

toxic, especially during the last quarter of the incubation period, whereas aged oil produced no 

detectable impacts. Fritts and McGehee (1982) concluded that oil contamination of nesting beaches 

would have its greatest impact on nests that were already constructed; nests made on fouled 

beaches are less likely to be affected, if at all. Residue oil may adhere to sand grains where eggs 

are deposited, later impeding hatchlings from successfully evacuating nests and ultimately leading to 

their death. Reproductive success could ultimately be impacted.

Hatchling and small juvenile turtles are particularly vulnerable to contacting or ingesting 

hydrocarbons because the currents that concentrate oil spills also form the debris mats in which 

young turtles are sometimes found (Carr, 1980; Collard and Ogren, 1990; Witherington, 1994). This 

would also be true for juvenile sea turtles that are sometimes found in floating mats of Sargassum. 

Oil slicks, slickets, or tarballs moving through offshore waters may foul Sargassum mats that 

hatchling and juvenile sea turtles inhabit, which would conceivably result in the loss of sea turtle 

habitat and/or incidental takes as defined under the ESA. High rates of oil contact in young turtles 
4-326 Gulf of Mexico Multisale EIS

suggest that bioaccumulation may occur over their potentially long lifespan. The result of adult sea 

turtles feeding selectively in surface convergence lines could be prolonged contact with viscous 

weathered oil (Witham, 1978; Hall et al., 1983). Balazs (1985) and Gramentz (1988) found tar to be 

the most prevalent marine pollution ingested by sea turtles. Bjorndal et al. (1994) examined 

digestive tracts from 51 juvenile sea turtles in Florida and found only 1 (<2%) to have tar in the gut. 

Similarly, Bugoni et al. (2001) found that only 1 turtle out of 50 (approximately 2%) stranded turtles 

that were analyzed had ingested oil. Some captive sea turtles exposed to oil either reduced the 

amount of time spent at the surface, possibly avoiding the oil, or became agitated and had short 

submergence levels (Lutcavage et al., 1995). Sea turtles pursue and swallow tarballs, and there is 

no firm evidence that free-ranging turtles can detect and avoid oil (Odell and MacMurray, 1986). 

Therefore, oil might have a more indirect impact on the behavior of sea turtles.

OSRA Modeling

The OSRA modeling results, which show the probabilities of a large spill (≥1,000 bbl) 

occurring in Federal offshore waters making contact with State offshore waters, are provided in 

Figure E-20. In general terms, coastal waters of the area may be contacted by many, frequent, 

small spills (≤1 bbl); few, infrequent, moderately-sized spills (>1 and <1,000 bbl); and a single large 

spill (≥1,000 bbl) as a result of a proposed action. Pipelines pose the greatest risk of a large spill 

occurring in coastal waters compared with platforms and tankers. Spill estimates over a 50-year 

time period are indicated in Table 3-17. According to Table 3-17, the majority of estimated spills 

would be small (<10 bbl). The actual number of spills that may occur in the future could vary from 

the estimated number. A spill size group for ≥10,000 bbl is not reasonably foreseeable; however, 

the impacts from such a spill are analyzed in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2016d). For more information on OSRA, refer to Chapter 3.2.1.4 (Analysis of 

Offshore Spills ≥1,000 bbl).

Depending on the time and location of a spill’s occurrence in coastal waters, its impact and 

resulting cleanup activities may interrupt sea turtle migration, feeding, mating, and/ or nesting activity 

for extended periods (i.e., days, weeks, or months). Spills originating in or dispersing through 

coastal waters of Texas or Louisiana may impact any of the five sea turtle species of the GOM. 

Aside from the acute impacts noted if sea turtles encounter an oil slick, the displacement of sea 

turtles to less suitable habitats from habitual feeding areas impacted by oil spills may increase 

vulnerability to predators, disease, or mortality from anthropogenic causes. A high incidence of 

juvenile sea turtle foraging occurs along certain coastal regions of the Gulf Coast. The interruption 

of mating and nesting activities for extended periods could influence the recovery of sea turtle 

populations.

Given the distribution of available leases and pipelines associated with a proposed action 

and the distribution of sea turtles in the northern GOM, the fate of an oil spill must be considered 

relative to the region and period of exposure. Chapter 3.2.1 details the persistence, spreading, and 

weathering process for offshore spills.
Description of the Affected Environment and Impact Analysis 4-327

Sea turtles are vulnerable to oil and dispersants at all life stages (i.e., eggs, post-hatchlings, 

juveniles, sub-adults, and adults), and there is no demonstrated avoidance behavior (Shigenaka 

et al., 2010). Impacts to sea turtles from OCS oil- and gas-related accidental oil spills are expected 

to range from negligible to moderate depending on the timing, size, and location of the spill, and 

the use of technologies to reduce the probability of an accidental event occurring. An example of a 

moderate impact would be a spill contacting an individual and causing injury that may be irreversible 

but that does not affect the continued viability of the population of that species.

Spill-Response Activities

In addition to the impacts from contact with hydrocarbons, spill-response activities could 

adversely affect sea turtle habitat and cause displacement from suitable habitat. Impact-producing 

factors might include artificial lighting from night operations, booms, machine and human activity, 

increased vessel traffic (refer to the “Transportation” section under “Routine Activities” above), 

equipment on beaches and in intertidal areas, sand removal and cleaning, and changed beach 

landscape and composition. Some of the resulting impacts from cleanup could include interrupted or 

deterred nesting behavior, crushed nests, entanglement in booms, and increased mortality of 

hatchlings because of predation during the increased time required to reach the water (Lutcavage 

et al., 1997). Increased human presence could influence turtle behavior and/or distribution, thereby 

stressing animals and making them more vulnerable to predators, the toxicological effects of oil, or 

other anthropogenic sources of mortality. The strategy for cleanup operations vary, depending on 

the season, recognizing that disturbance to the nest may be more detrimental than the oil (Fritts and 

McGehee, 1982). After passage of the Oil Pollution Act of 1990, seagrass beds and live bottom

communities are expected to receive individual consideration during spill cleanup. Required spill 

contingency plans include special notices to minimize adverse effects from vehicular traffic during 

cleanup activities and to maximize protection efforts to prevent contact of these areas with spilled oil.

Little is known about the effects of dispersants on sea turtles and, in the absence of direct 

testing, impacts are difficult to predict. Dispersant components absorbed through the lungs or gut 

may affect multiple organ systems and interfere with digestion, excretion, respiration, and/or saltgland function. Inhalation of dispersant can interfere with function through the surfactant (detergent) 

effect. These impacts are likely similar to the empirically demonstrated effects of oil alone (Hoff and 

Shigenaka, 2003). The impacts to sea turtles from chemical dispersants could include nonlethal 

injury (e.g., tissue irritation, chemical burns, and inhalation), long-term exposure through 

bioaccumulation, infection, and potential shifts in distribution from some habitats (USDOC, NOAA, 

2015k; Shigenaka et al., 2010). For more information on dispersants, refer to Chapter 3.2.8.2.2

(Offshore Response, Containment, and Cleanup Technology).

Due to spill response and cleanup efforts, much of an oil spill may be recovered before it 

reaches the coast. However, cleanup efforts in offshore waters may result in additional harm or 

mortality of sea turtles, particularly to neonates and juveniles. Spill-response activities are expected 

to have minimal adverse effects on sea turtles based on the short exposure duration of the activities 

and are more likely to have a positive effect on sea turtles over time given the removal of spilled oil, 
4-328 Gulf of Mexico Multisale EIS

turtle and nest relocation, and contact prevention efforts. Due to the nature of the response 

activities, minor impacts could occur by a behavioral change of sea turtles in the immediate area. 

Therefore, impacts from spill-response activities are expected to be negligible to minor. There are 

also mitigations and plans in place (e.g., from USCG, BSEE, States, NMFS, FWS, and NPS) to 

decrease impacts to sea turtles during response activities, which increase surveillance and the 

detection of animals, thus reducing potential impacts through avoidance measures.

Marine Trash and Debris

A wide variety of trash and debris is commonly observed in the GOM. Marine debris remains 

a continuous threat to sea turtles (Schuyler et al., 2014). Marine trash and debris comes from a 

variety of land-based and ocean sources (Cottingham, 1988). Some material is accidentally lost 

during drilling and production operations. Turtles may become entangled in drifting debris and 

ingest fragments of synthetic materials (Carr, 1987b; USDOC, NOAA, 1988; Mrosovsky et al., 2009; 

Santos et al., 2015). Once entangled, turtles may drown, incur impairment to forage or avoid 

predators, sustain wounds and infections from the abrasive or cutting action of attached debris, or 

exhibit altered behavior that threaten their survival (Laist, 1997). Both entanglement and ingestion 

have caused the death or serious injury of individual sea turtles (Balazs, 1985). Balazs (1985) 

compiled dozens of records of sea turtle entanglement, ingestion, and impaction of the alimentary 

canal by ingested plastics.

The marked tendency of leatherbacks to ingest plastic has been attributed to the 

misidentification of the translucent films as jellyfish. Lutz (1990) concluded that turtles would actively 

seek out and consume plastic sheeting. Ingested debris may block the digestive tract or remain in 

the stomach for extended periods, thereby lessening the feeding drive, causing ulcerations and 

injury to the stomach lining, or perhaps even providing a source of toxic chemicals (Laist, 1997). 

Weakened animals are then more susceptible to predation and disease; they are also less able to 

swim, breed, or nest successfully. Microplastics are becoming an increasing concern for ingestion 

by all species of sea turtle, and they can also decrease maximum temperatures in beach sediments, 

which leads to sex bias in sea turtles due to temperature-dependant sex determination of the 

offspring (Bergmann et al., 2015).

Witherington (1994) studied post-hatchling loggerheads in drift lines 8-35 nmi (9-15 mi; 

15-24 km) east of Cape Canaveral and Sebastian Inlet, Florida. Out of 103 turtles captured, 

17 percent of the animals contained plastic or other synthetic fibers in their stomachs or mouths. 

Without mitigation, marine debris impacts would be negligible to moderate. Operators must comply 

with the guidelines provided in NTL 2015-BSEE-G03, “Marine Trash and Debris Awareness and 

Elimination.” BOEM would expect the NTLs to become mandatory under the Protected Species 

Stipulation which is typically applied at the lease sale stage. The BSEE prohibits the disposal of 

equipment, containers, and other materials into offshore waters by lessees (30 CFR § 250.300). 

Therefore, expected marine trash debris impacts to sea turtles from a proposed action should be 

negligible. 
Description of the Affected Environment and Impact Analysis 4-329

4.9.2.2.3 Cumulative Impacts

This cumulative analysis considers the effects of impact-producing factors related to a 

proposed action along with impacts of other commercial, military, recreational, offshore, and coastal 

activities that may occur and adversely affect populations of sea turtles in the same general area of 

a proposed action.

OCS Oil- and Gas-Related Impacts

The major impact-producing factors resulting from cumulative OCS energy-related activities 

associated with a proposed action that may affect GOM sea turtles and their habitats include those 

already described under “Routine Activities” and “Accidental Events” sections above, i.e., geological 

and geophysical activities, transportation, discharges, marine debris, decommissioning, noise, and 

accidental oil spills and spill response. Chapters providing supporting material for the sea turtle 

analysis include Chapters 4.1 (Air Quality), 4.2 (Water Quality), 4.3 (Coastal Habitats), 

4.4 (Deepwater Habitats), 4.5 (Sargassum and Associated Communities), 3.1 (Offshore ImpactProducing Factors and Scenario), 3.1.4 (Transport), 3.1.6 (Decommissioning), and 5.7 (Endangered 

Species Act). The cumulative impact of these ongoing OCS energy-related activities on sea turtles 

is expected to result in a number of chronic and sporadic sublethal effects (i.e., behavioral effects 

and nonfatal exposure to or intake of OCS oil- and gas-related contaminants or discarded debris) 

because these activities may stress and/or weaken individuals of a local group or population and 

may predispose them to infection from natural or anthropogenic sources.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related impact-producing factors that may affect sea turtle populations 

include: accidental oil spills and response (State oil and gas), vessel traffic, commercial fishing (i.e., 

bycatch and entanglement), dredging and construction, habitat loss, historic overexploitation (that 

led to the initial listing of the species), marine trash and debris, military operations, natural 

phenomena including disasters and climate change, noise (i.e., from commercial fishing, recreational 

vessels, military activities, commercial shipping, tourism, construction), pathogens/disease, scientific 

research, and transportation and related noise (e.g., commercial shipping and research vessels). 

With the exception of some of the dredging activities being regulated by BOEM’s Marine Minerals 

Program, BOEM does not regulate any of the aforementioned non-OCS oil- and gas-related 

activities, though some may be mitigated/regulated by other agencies. The factors that may have 

the largest impacts to sea turtles are outlined below.

The Gulf Coast is a well-populated and growing area, and development of previously 

unusable land for residential and commercial purposes is common. Increased human activity along 

the coast and offshore results in increased runoff and dumping. Many areas around the GOM 

already suffer from high contaminant levels due to river and coastal runoff and discharges. 

Contaminants may accumulate in species or in prey species. Sea turtles frequent coastal habitats to 

seek food (such as sponges, jellyfish, crabs, or seagrass) and shelter (Bjorndal, 1997). Coastal 

areas are also used by juvenile and adult Kemp’s ridleys in Louisiana (Ogren, 1989; Shaver et al., 
4-330 Gulf of Mexico Multisale EIS

2013). Submerged areas of vegetation may be lost or damaged by activities (e.g., dredging) that 

alter salinity, turbidity, or natural tidal and sediment exchange.

Accidental oil spills and spill response by State oil and gas activities may occur with impacts 

similar to those described above for OCS oil- and gas-related activities. Impacts would be mainly 

dependent on the size and location of the spill, although State oil and gas activities are located in 

shallow waters closer to the coast, so there may be an increased potential for oil contacting the 

coastline. Naturally occurring seeps are also a source of oil that occurs in the water and potentially 

contacting the coast.

Numerous commercial and recreational fishing vessels use areas in the northern GOM. 

Tanker imports and exports of crude and petroleum products into the GOM are projected to 

increase. Crude oil would continue to be transported to the Gulf for refining from other areas of the 

United States (i.e., Alaska, California, and the Atlantic). Recreational pursuits can have an adverse 

effect on sea turtles through propeller and boat strike damage. Areas closer to shore where sea 

turtles regularly migrate, mate, nest, and forage (Shaver et al., 2013; Hart et al., 2010 and 2012) 

may have an elevated likelihood of vessel strikes or avoidance to aircraft, due to increased 

transportation in those areas.

Sea turtle bycatch in the GOM is high, specifically for the longline fishery, and can be driven 

by turtle density, fishing intensity or both (Lewison et al., 2014). For example, the chief areas used 

by Kemp’s ridleys (coastal waters <59 ft [18 m] in depth) overlap with the shrimp fishery (Renaud, 

1995; Shaver et al., 2013). A major source of mortality for loggerhead and Kemp’s ridleys is capture 

and drowning in shrimp trawls (Caillouet et al., 1996; Epperly and Teas, 2002; Shaver et al., 2013; 

USDOC, NMFS and USDOI, FWS, 2015), which accounts for most (up to 98%) of the sea turtle 

bycatch in the U.S. (Finkbeiner et al., 2011). Crowder et al. (1995) reported that 70-80 percent of 

turtle strandings were related to interactions with this fishery. Caillouet et al. (1996) found a 

significant positive correlation between turtle stranding rates and shrimp fishing intensity in the 

northwestern GOM. The Kemp’s ridley population, because of its distribution and small numbers, is 

at greatest risk. To reduce fishery impacts to turtles, NMFS has required the use of turtle excluder 

devices in southeast U.S. shrimp trawls since 1989 and has increased efforts over the years for 

adequate protection to decrease the number of strandings. The use of turtle excluder devices was 

believed to reduce hard-shelled sea turtle captures by 97 percent; however, evidence has shown 

that a large proportion of turtles are too big to fit through the openings (Epperly and Teas, 2002). 

Since implementing the required use of turtle excluder devices throughout the shrimp fishing 

industry, gear improvements continue to be introduced nearly annually. Turtles may be accidentally 

caught and killed in finfish trawls, seines, gill nets, weirs, traps, longlines, and driftnets (Witzell, 

1992; Brady and Boreman, 1994; Epperly and Teas, 2002; USDOC, NMFS and USDOI, FWS, 

2013a and 2013b). Florida and Texas have banned all but very small nets in State waters. 

Louisiana, Mississippi, and Alabama have also placed restrictions on gillnet fisheries within State 

waters, such that very little commercial gillnetting takes place in southeast waters. The State fishery 

for menhaden in the State waters of Louisiana and Texas is managed by the Gulf States Marine 
Description of the Affected Environment and Impact Analysis 4-331

Fisheries Council and is not federally regulated for sea turtle take. Fishery interactions with sea 

turtles remain a major source of mortality.

Dredge-and-fill activities occur in many of the coastal areas inhabited by sea turtles and can 

create impacts, but agencies permitting these activities must consult under the ESA and protective 

measures would be required to prevent adverse impacts. Operations range in scope from propeller 

dredging (scarring) by recreational boats to large-scale navigation dredging and fill for land 

reclamation. Dredging operations affect turtles through incidental take (entrainment) and habitat 

degradation (Michel et al., 2013b). The construction and maintenance of Federal navigation 

channels, as well as dredging offshore sand resource areas (i.e., borrow areas) to support coastal 

restoration and beach nourishment projects, have been identified as sources of sea turtle mortality. 

Hopper dredges can entrain and kill individuals, presumably either by catching sea turtles 

resting/foraging on the bottom or as the drag arm of the moving dredge overtakes a slower-moving 

animal. Hopper dredging has caused turtle mortality in coastal areas (Slay and Richardson, 1988). 

Nearly all sea turtles entrained by hopper dredges are dead or dying when found (NRC, 1990). 

However, there continues to be engineering of modified turtle excluding devices for hopper dredges 

to reduce entrainment (Henriksen et al., 2015). In addition to direct take, channelization of the 

inshore and nearshore areas can degrade foraging and migratory habitats via spoil dumping, 

degraded water quality/clarity, and altered current flow.

Construction, beach front development, beach vehicle traffic, beach erosion, nest predation, 

and artificial lighting are activities that disturb sea turtles or their nesting beaches (Garber, 1985; 

Conant et al., 2009). Vehicles and beach cleaning activities may crush nests, reducing hatching 

success (Coston-Clements and Hoss, 1983). Physical obstacles, such as deep tire tracks and 

expanded sand piles, may obstruct hatchling turtles from entering the sea or increase their stress 

and susceptibility to predation (Witham, 1995). Obstructions to the high watermark prevent nesting, 

and breakwalls are the most common and severe type of obstruction. Erosion can result in the loss 

of habitat, and artificial lighting affects nesting beaches. Human interference has hastened erosion 

in many places. Artificial lighting from buildings, street lights, and beachfront properties may 

disorient hatchlings, as well as adults (Witherington and Martin, 1996). Females tend to avoid areas 

where beachfront lighting is most intense; turtles also abort nesting attempts more often in lighted 

areas. Hatchlings are attracted to lights and may become disoriented, increasing their vulnerability 

to terrestrial predators. As part of NRDA’s early restoration efforts, there is a project focused on 

restoring the night sky or identifying and reducing artificial lighting on shorelines. Details on the 

project can be found on NOAA’s Habitat Conservation website (USDOC, NOAA, 2016b). 

Condominiums sometimes block sunlight on nesting beaches, which could presumably affect sex 

ratios of hatchlings (the sex of a turtle is dependent on egg temperature) by increasing the number 

of males produced (Mrosovsky et al., 1995). Increased human activities, such as organized turtle 

watches, on nesting beaches may adversely affect nesting activity (Fangman and Rittmaster, 1994; 

Johnson et al., 1996). Species that prey on sea turtle nests include fire ants, raccoons, armadillos, 

and opossums. Sea turtles entering coastal or inshore areas have been affected by entrainment in 

the cooling water systems of electrical generating plants (NRC, 1990). Deaths can result from 

injuries sustained in transit through the intake pipe, from drowning in capture nets, and perhaps from 
4-332 Gulf of Mexico Multisale EIS

other causes before entrainment (Bressette et al., 1998). Thermal effluents from power plants may 

cause hatchlings to become disoriented and reduce their swimming speed (O’Hara, 1980). These 

effluents may also degrade important foraging seagrass and reef habitats (Coston-Clements and 

Hoss, 1983). It has been suggested that power plants could also provide positive impacts by 

providing warm-water refuge in some areas (McDonald et al., 1994; Turner-Tomaszewicz and 

Seminoff, 2012).

Sand mining, beach nourishment, and oil-spill cleanup operations may remove sand from the 

littoral zone and temporarily disturb onshore sand transport, potentially disturbing nesting activities. 

BOEM has evaluated the use of sand resources for levee, beach, and barrier island restoration 

projects. For more than 20 years, BOEM has provided over 113 million yd3 (85 million m3

) of OCS 

sand for 40 coastal projects, restoring over 279 mi (433 km) of national coastline. As the demand for 

sand for shoreline protection and restoration increases, OCS sand and gravel has become an 

increasingly important resource. Use of these resources would require coordination with BOEM for 

appropriate authorization. Sea turtles are included in the potential impacts identified for sand 

dredging projects. Mitigating measures include requiring stipulations to protect sea turtles when it is 

determined that there is a likelihood of sea turtle presence within the area during the dredging 

operation, and a trailing suction hopper dredge is used. As part of NRDA’s early restoration efforts, 

there are at least three artificial reef projects totaling $7.7 million in the GOM that would provide 

more shelter and feeding habitat for turtles. Details on these projects can be found on NOAA’s 

website (USDOC, NOAA, 2016c).

Explosive discharges, such as those used for COE structure removals or coastal 

construction, can cause injury to sea turtles (Duronslet et al., 1986), but they are subject to ESA 

consultation with NMFS. Although sea turtles far from the site may suffer only disorientation, those 

near detonation sites could sustain fatal injuries. Injury to the lungs, intestines, and/or auditory 

system could occur. Other potential impacts include physical or acoustic harassment. 

Resuspension of bottom sediments, increased water turbidity, and mobilization of bottom sediments 

due to explosive detonation are considered to be temporary effects.

Historically, sea turtles were overexploited by the poaching of eggs and individuals, and with 

the added pressures of other historic non-OCS oil- and gas-related impact-producing factors 

described in this section (e.g., commercial fishing), NMFS determined there was a need to list them 

under the ESA. Human consumption of turtle eggs, meat, or byproducts still occurs worldwide and 

depletes turtle populations (Conant et al., 2009; USDOC, NMFS and USDOI, FWS, 2007b and 

2013b). Commercial harvests are no longer permitted within continental U.S. waters, and Mexico 

has banned such activity (Aridjis, 1990).

Chronic pollution, including industrial and agricultural wastes and urban runoff, threatens sea 

turtles worldwide (Frazier, 1980; Hutchinson and Simmonds, 1991). Some turtle species have 

lifespans exceeding 50 years (Congdon, 1989; Frazer et al., 1989) and are secondary or tertiary 

consumers in marine environments, creating the potential for bioaccumulation of heavy metals, 

pesticides, and other contaminants (Davenport et al., 1990; Lutz and Lutcavage, 1989) in their 
Description of the Affected Environment and Impact Analysis 4-333

tissues. Organochlorine pollutants (pesticides) have been documented in eggs, juveniles, and adult 

turtles (Rybitski et al., 1995). The DDE from DDT is the pesticide present in the greatest 

concentrations in sea turtles (Camacho et al., 2013). Contaminants could stress the immune system 

of sea turtles or act as carcinogens indirectly by disrupting neuroendocrine functions (Colborn et al., 

1993; Camacho et al., 2012).

Numerous sources of aircraft fly over the coastal and offshore areas and create noise that 

may cause behavioral responses in sea turtles as described in the “Noise” section above. The air 

space over the GOM is used extensively by DOD for conducting various air-to-air and air-to-surface 

operations. Eleven military warning areas and five water test areas are located within the GOM, as 

stated in NTL 2014-BOEM-G04, “Military Warning and Water Test Areas” (Figure 2-7). Additional 

activities, including vessel operations, discharges associated with military activities, and ordnance 

detonation, also may affect sea turtles. Subject to the Federal Aviation Administration’s guidelines, 

private and commercial air traffic further traverse these areas and have the potential to cause 

impacts to sea turtles.

Natural catastrophes, including storms, floods, droughts, and hurricanes, can also 

substantially damage nesting beaches and coastal areas used by sea turtles (Agardy, 1990; Fish 

et al., 2015). Abnormally high tides and waves generated by storms may exact heavy mortality on 

sea turtle nests by washing them from the beach, inundating them with sea water, or altering the 

depth of sand covering them. Furthermore, excessive rainfall associated with tropical storms may 

reduce the viability of eggs. Turtles could be harmed in rough seas by floating debris (Milton et al., 

1994). In addition, the hurricane season for the Caribbean and Western Atlantic (June 1 through 

November 1) overlaps the sea turtle nesting season (March through November) (NRC, 1990). Nests 

are vulnerable to hurricanes during the incubation period as well as when hatchlings evacuate the 

nest. Hurricanes can cause mortality at turtle nests through immediate drowning from ocean surges, 

nest burial, or exhumation before hatching, and after hatching as a result of radically altered beach 

topography. Natural phenomena could result in numerous impacts to sea turtles as well. Rising sea 

levels could further diminish available nesting beach habitat. Changing ocean temperatures may 

alter distribution patterns for sea turtle prey (i.e., jellyfish for leatherbacks). This could impact adult 

survivability as well as nesting success. Warming temperatures may change the sex ratios of 

hatchlings as sex is determined by nest temperature. Larger, more frequent storms can physically 

impact nesting beaches (Intergovernmental Panel on Climate Change, 2016).

Noise from non-OCS oil- and gas-related activities may impact sea turtles and is described in 

Chapter 3.3.2.7. Areas closer to shore normally have higher noise levels (more human-use), and 

levels typically drop off moving into deeper water. Non-OCS noise sources include, but are not 

limited to, commercial fishing vessels, recreational vessels, scientific vessels, tourism vessels and 

watercraft, military operations, lightning, aircraft, State oil and gas activities, etc. Sea turtles have a 

high potential for recoverable injury from temporary hearing loss (i.e., temporary threshold shift) and 

behavioral modifications only when they are close in proximity to the source. Mortality and injury 

caused by shipping and continuous noise are expected to have low levels of relative risk even if a 

sea turtle is relatively near the source. The risk for temporary threshold shift near the source is 
4-334 Gulf of Mexico Multisale EIS

moderate, while the risk for masking may be high both at near and intermediate distances from the 

source, and the risk for behavioral modifications near the source are high and moderate at 

intermediate distances from the source. Effects from sound are relative to the source type, distance 

to the source, frequency, intensity and duration of the source, and distance to the animal.

Sea turtles are affected by pathogens and disease, which may be secondary infections 

following other stressors, such as an entanglement injury or nutritional deficiencies. Some of these 

diseases are described in the affected environment and include fibropapillomatosis (believed to be 

caused by a herpes virus); viral, bacterial, and mycotic (fungal) infections; parasites (internal or 

external); and other environmental health problems (e.g., hypothermic stunning). Van Houtan et al. 

(2014) found fibropapillomatosis could be linked, at least in part, to eutrophication.

Scientific research may impact sea turtles. Many studies require the attachment of 

equipment to turtle shells that could reduce fitness, and often turtles must be caught and/or held 

captive for a period of time before being released back into their natural environment. This could 

cause stress to a turtle; however, research is typically seen as an overall positive impact due to 

learning more about life histories of turtles and, therefore, allowing for improved species 

management.

Due to the overall non-OCS oil- and gas-related activities affecting habitat, prey, and general 

health of sea turtles, the impacts could be negligible to major; however, the ESA process, including 

5-year status reviews, general consultations with FWS and NMFS, and implementation of 

conservation measures, would protect sea turtle populations.

The incremental contribution to cumulative impacts on sea turtles as a result of a proposed 

action, even when taking into consideration the potential impacts of the Deepwater Horizon

explosion, oil spill, and response, non-OCS oil- and gas-related factors and the minimization of OCS 

oil- and gas-related impacts through lease stipulations and regulations, would be expected to be 

negligible. 

4.9.2.2.4 Incomplete or Unavailable Information

Unavailable information provides challenges in understanding the baseline conditions and 

changes within sea turtle populations. The impacts associated with the Deepwater Horizon

explosion, oil spill, and response makes an understanding of the cumulative impacts less defined but 

overall changes the baseline as in less numbers of individual species. Not all of the information 

collected during the NRDA process and used as a basis for their determinations is publicly available. 

BOEM used existing information and reasonably accepted scientific methodologies to extrapolate 

from publicly available information on sea turtles in completing the relevant analysis of sea turtle 

populations. There are existing leases in the GOM with ongoing or the potential for exploration, 

drilling, and production activities. In addition, non-OCS oil- and gas-related activities would continue 

to occur in the GOM irrespective of a proposed action (e.g., fishing, military activities, and scientific 

research). Also, little is known about the early life history of leatherbacks regarding the “lost years” 
Description of the Affected Environment and Impact Analysis 4-335

(Carr, 1986). BOEM used available research and presented what is known in Chapter 4.9.2.1. 

Therefore, BOEM concludes that the unavailable information from these events may be relevant to 

foreseeable significant adverse impacts to sea turtles because the full extent of impacts on sea 

turtles is not known, but BOEM has determined that the information is not essential to a reasoned 

choice among alternatives for this Multisale EIS (including the No Action and Action Alternatives).

4.9.2.2.5 Alternatives A, B, C, and D

With respect to sea turtles, the effects associated with selection of any of the action 

alternatives would be equivalent because of the diversity and distribution of sea turtles throughout 

the potential Area of Interest. The preceding analyses assumed a wide distribution of species and 

considered impacts to sea turtles occurring in a wide range of habitats across all planning areas. 

While a proposed WPA lease sale (Alternative C) would be in a smaller area with much less 

projected activity than a proposed regionwide (Alternative A) or proposed CPA/EPA lease sale 

(Alternative B) as described in Chapter 3, sea turtles are distributed throughout the planning areas. 

As such, activities isolated to specific planning areas pose similar potential impacts to populations as 

do activities occurring in all planning areas. Therefore, a similar mix of species would be exposed to 

the analyzed impact-producing factors, regardless of the specific action alternative selected. The 

activities proposed under Alternatives A, B, C, and D would directly impact sea turtles within the 

GOM and would contribute incrementally to the cumulative effects on these species.

Sea turtles of all five species are present throughout the northern GOM; however, only 

Kemp’s ridley and loggerheads nest on beaches in the GOM. Individual animals make migrations 

into nearshore waters as well as other areas of the Gulf of Mexico, Atlantic Ocean, and Caribbean 

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

mortality led to rapid declines of sea turtle populations.

Anthropogenic impacts, as discussed in the cumulative impact chapter above, continue to 

pose the greatest threat to sea turtles. Sea turtle critical habitat and nesting sea turtles are 

threatened with climate change, natural disasters, beach erosion, armoring, nourishment, artificial 

lighting, beach driving and cleaning, increased human presence, human response to disasters, 

coastal development, recreational beach use including equipment and furniture, exotic dune and 

beach vegetation, natural habitat obstructions, military testing and training activities, poaching, and 

nest predation.

Although there would always be some level of incomplete information relevant to the impacts 

from activities under a proposed action on GOM sea turtles, BOEM does not believe it is essential to 

a reasoned choice among alternatives. To date, there is no peer-reviewed scientific information 

available supporting that any impacts expected from a proposed action would be expected to rise to 

the level of reasonably foreseeable population-level impacts. BOEM acknowledges that impacts 

from routine activities or accidental events could be greater on individuals or populations already 

affected by other OCS oil- and gas-related or non-OCS oil- and gas-related impact-producing 

factors. Nevertheless, routine activities are ongoing in a proposed action area as a result of active 
4-336 Gulf of Mexico Multisale EIS

leases and related activities. Further, activities that could result in an accidental spill in the GOM 

would be ongoing whether or not a proposed action occurred.

In order to minimize potential interactions and impacts to sea turtles, operators are required 

to follow all applicable lease stipulations and regulations, as clarified by NTLs. The operator’s 

compliance with NTL 2016-BOEM-G01 (“Vessel-Strike Avoidance and Injured/Dead Protected 

Species Reporting”) and NTL 2015-BSEE-G03 (“Marine Trash and Debris Awareness Elimination”) 

and the transient nature of sea turtles, as well as the limited scope, timing, and geographic location 

of a proposed action, would result in a minimized impact from a proposed action on sea turtles. In 

addition, NTL 2016-BOEM-G02, “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program,” minimizes the potential of harm from seismic operations to 

sea turtles and marine mammals; these mitigations include onboard observers, airgun shut-downs 

for whales in the exclusion zone, ramp-up procedures, and the use of a minimum sound source.

Because of the mitigations (e.g., BOEM and BSEE’s proposed compliance with NTLs) 

described above, routine activities and accidental events related to a proposed action are not 

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

populations in the northern GOM. Lethal impacts could occur from chance collisions with OCS 

service vessels or ingestion of accidentally released plastic materials from OCS vessels and 

facilities, which would be considered moderate impacts.

While the impact-producing factors associated with a proposed action could potentially 

impact sea turtles if unmitigated, the incremental contribution to cumulative impacts on sea turtles, 

even when taking into consideration the potential impacts of the Deepwater Horizon explosion, oil 

spill, and response, non-OCS oil- and gas-related factors and the minimization of OCS oil- and gasrelated impacts through lease stipulations and regulations, would be expected to be negligible as a 

result of a proposed action. Within the GOM, there is a long-standing and well-developed OCS 

Program (more than 50 years), and population-level impacts to sea turtles are not anticipated.

4.9.2.2.6 Alternative E—No Action

Under Alternative E, there would be no lease sale held and therefore no postlease activities 

related to such a lease sale to impact sea turtles. However, there would be continuing impacts to 

sea turtles related to previous OCS oil- and gas-related development and non-OCS oil- and gasrelated activities. Sea turtles move in the GOM over great spatial scales and they would be 

expected to move in and out of the previously leased blocks. In addition, many of these blocks 

already have existing OCS oil- and gas-related development, and sea turtles would continue to be 

impacted by routine activities and accidental events from this pre-existing OCS development.

4.9.3 Beach Mice (Alabama, Choctawhatchee, Perdido Key, and St. Andrew)

The following four subspecies of beach mouse (Peromyscus polionotus) occupy restricted 

habitats in the mature coastal dunes of Florida and Alabama and are federally listed as endangered: 

Alabama (P.p. ammobates), Perdido Key (P.p. trisyllepsis), and Choctawhatchee (P.p. allophrys) 
Description of the Affected Environment and Impact Analysis 4-337

(listed June 6, 1985) (Federal Register, 2006b) and St. Andrew (P.p. peninsularis) (listed 

December 18, 1998) (Federal Register, 1998). Current critical habitat is included in the critical 

habitat map (Figure 4-25). Populations of the listed subspecies have fallen to levels approaching 

extinction. These four subspecies of beach mice are similar in appearance but can be identified by 

pelage color and location (Bowen, 1968). The approach of this analysis is to focus on the potential 

impact-producing factors from OCS oil- and gas-related routine activities (i.e., exploration, 

development, and production), as well as accidental events and cumulative impacts, and to define 

impact-level measures for each impact-producing factor (refer to Table 4-18 in Chapter 4.9).

4.9.3.1 Description of the Affected Environment

Beach mice are restricted to the coastal barrier sand dunes along coastal Alabama and the 

Florida panhandle, and are nocturnal herbivores that forage on sea oats and beachgrass, 

occasionally consuming invertebrates (Ehrhart, 1978; Moyers, 1996). For a detailed description of 

dunes, refer to Chapter 4.3.2.1 (Coastal Barrier Beaches and Associated Dunes, “Description of the 

Affected Environment”). Optimal overall beach mouse habitat is currently thought to be comprised of 

a heterogeneous mix of interconnected habitats including frontal dunes, scrub (tertiary) dunes farther 

inland, and interdunal areas between these dune habitats. Beach mice dig burrows mainly in the 

frontal dunes and interior scrub dunes where the vegetation provides suitable cover for avoiding 

predators, storing food, and providing cover during the day and during inclement weather conditions.

Critical habitat for the four subspecies of beach mouse extend from Baldwin County, 

Alabama, to Gulf County, Florida. The beach and dunal areas that are associated with beach 

mouse habitat include the coastal regions associated with the CPA and EPA. Complete descriptions 

of current critical habitat can be found in USDOI, FWS (2010a) and Figure 4-25. Due to the 

dynamic nature of mouse populations that fluctuate with environmental conditions, abundance 

estimates are unreliable. Trends in populations are determined using percent area occupied, with 

ongoing monitoring efforts for each of the beach mouse subspecies.

4.9.3.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from the activities described in 

Chapter 3 that are associated with non-OCS and OCS oil- and gas-relate activities. This analysis 

applies to all considered alternatives. Because of the diversity and distribution of species in the Area 

of Interest, the level of impacts would be the same generally for Alternatives A, B, and D. 

Alternative C would have no impacts since no beach mice habitat is near the WPA proposed lease 

sale area. However, Alternative E, No Action, would only have impacts associated with ongoing 

activities from past lease sales and non-OCS oil- and gas-related activities. Following the 

environmental consequences chapter, there is a summary of the potential impacts as they relate to 

the action alternatives.
4-338 Gulf of Mexico Multisale EIS

4.9.3.2.1 Routine Activities

There are no impact-producing factor associated with routine activities that may affect beach 

mice or their critical habiat. All routine activity is expected to be far enough from beach mouse 

habitat that no impacts are expected to occur.

4.9.3.2.2 Accidental Events

The major impact-producing factors resulting from accidental events reasonably expected to 

be associated with the OCS oil- and gas-related activities that may affect beach mice include coastal 

and offshore oil spills, spill-response activities, and marine trash and debris (Chapter 3.2.7) that 

would reach their habitat.

Oil spills may directly impact beach mice since direct contact with spilled oil can cause skin 

irritation and/or cause the fur to mat, resulting in the loss of its insulative properties for 

thermoregulation. Other direct toxic impacts may result from oil ingestion, absorption, or respiratory 

effects from the inhalation of fumes. Indirect impacts may include contamination and depletion of 

food supply, destruction of habitat, and fouling of burrows. There is no definitive information on the 

persistence of oil in the event that a spill was to contact beach mouse habitat. In Prince William 

Sound, Alaska, after the Exxon Valdez spill in 1989, buried oil has been measured in the intertidal 

zone of beaches, but no effort has been made to search for residual buried oil above high tide. 

Similarly, NRC (2003) makes no mention of studies of oil left above high tide after a spill. 

Regardless of the potential for persistence of oil in beach mouse habitat, a slick cannot wash over 

the foredunes unless carried by a heavy storm swell. The oiling of beach mouse populations could 

result in local extinction, but this is unlikely given that the chance of a spill occurring and contacting 

the habitat is between <0.5 and 1 percent after 10 or 30 days of a spill, and the area of viable habitat 

is broad relative to the area potentially contacted by a large spill according to the OSRA model (refer 

to Chapter 3.2.1.4). A reasonably foreseeable noncatastrophic oil spill is not likely to occur near 

beach mouse habitat; therefore, it would have negligible impacts to beach mice. 

Impacts can also occur from spill-response activities. Vehicle traffic and other activities 

associated with oil-spill cleanup can degrade preferred habitat and crush burrows, resulting in 

displacement of mice from these areas. These impacts could be reduced if personnel are properly 

trained to identify and avoid sensitive habitat (which may be on short notice if under emergency 

conditions). Impacts from an accidental oil spill and cleanup efforts would be negligible because a 

reasonably foreseeable noncatastrophic oil spill is not likely to occur near beach mouse habitat. For 

more information on habitat impacts from accidental events, refer to Chapter 4.3.2.3 (Coastal 

Barrier Beaches and Associated Dunes).

Impacts to beach mice may occur directly to the animal or its habitat. Marine trash and 

debris could affect beach mice due to the potential to ingest and/or become entangled. The BSEE 

has taken measures to reduce marine debris issue by imposing marine debris awareness and 

prevention measures on the oil and gas industry through NTL 2015-BSEE-G03, which provides 

guidance to industry operators to reduce trash and debris elimination into the marine environment 
Description of the Affected Environment and Impact Analysis 4-339

and informs operators of regulations set by other regulatory agencies (i.e., USEPA and USCG). 

This mitigation is a binding part of leases through the Protected Species Stipulation. The OCS 

oil- and gas-related proposed activities may contribute minimal marine debris or disruption to beach 

mouse areas, but the impacts would be negligible. Due to the proximity of the beach mouse habitat 

to any OCS oil- and gas-related activity, any accidental loss of debris as a result of OCS oil- and 

gas-related activities would be minimal.

4.9.3.2.3 Cumulative Impacts

This cumulative analysis considers factors that affect beach mice, including oil spills, 

alteration and reduction of habitat, predation (especially from feral or free-roaming domestic cats) 

and competition, ingestion and entanglement of beach trash and debris, beach development, coastal 

spills, and natural catastrophes (i.e., hurricanes and tropical storms).

OCS Oil- and Gas-Related Activities

Oil spills that are related to the importing and transporting of oil resulting from prior and 

future lease sales are not expected to contact beach mice or their habitats because the species lives 

above the intertidal zone where contact is less likely. For more information on impacts to the dune

habitat, refer to Chapter 4.3.2 (Coastal Barrier Beaches and Associated Dunes). Therefore, the 

expected incremental contribution of OCS oil- and gas-related activities to the cumulative impacts is 

negligible, given the proximity of beach mouse habitat and the relatively small likelihood that a 

reasonably foreseeable spill would reach their habitat.

Non-OCS Oil- and Gas-Related Activities

The greatest impacts to beach mice are based on impacts to their habitat. Non-OCS oil- and 

gas-related activities may also incur negative impacts to the habitat or directly by interactions with 

other species. Cumulative impacts from coastal development, State oil and gas activities, predation, 

recreational beach use, trash and debris, disease, hurricanes, and the effects of sea-level rise may 

affect the protected subspecies of beach mice. For a full list of cumulative impacts to beach habitat, 

refer to Chapter 4.3.2 (Coastal Barrier Beaches and Associated Dunes).

Habitat Alteration and Reduction

Coastal development is the greatest threat to beach mouse survival. Habitat reduction and 

fragmentation have affected the ability of beach mice to quickly recover following tropical storms. 

Habitat fragmentation also reduces genetic diversity by limiting gene flow within contiguous habitat. 

Critical habitat provides an area of protected refugia for these subspecies of beach mouse and is 

important to sustain each population.

Predation and Competition

Non-native predators such as red fox and domestic cats pose a threat to beach mice. Feral 

cats may pose one of the greatest threats to beach mice (Bowen, 1968; Humphrey and Barbour, 
4-340 Gulf of Mexico Multisale EIS

1981; Moyers, 1996). Gore and Schaeffer (1993) showed a significant correlation between the 

presence of cat tracks and beach mouse tracks on Santa Rosa Island. Predation by cats in 

conjunction with other threats may result in significant adverse impacts to beach mice (Federal 

Register, 1998). The recovery plans for these four subspecies of beach mice include a component 

of managing feral and free-ranging cats near beach mouse habitat by educating the public and 

control measures to eliminate feral cat populations near dune habitats. Predation and competition 

are serious concerns for beach mice regarding impacts to populations.

Hurricanes

Population viability analysis is essentially a demographic modeling exercise to predict the 

likelihood that a population would continue to persist over time (Groom and Pascual, 1998). The 

objective of a population viability analysis for beach mice is to determine how large and what 

configuration of habitat is necessary to reasonably assure that the species would survive to recover. 

The most recently revised model, which includes data from hurricanes, projects a risk of extinction of 

26.8 ± 1.0 percent over the next 100 years. Falcy (2011) used modeling to show recovery of 

Alabama beach mouse populations during the 4 years after Hurricane Ivan (2004) and Hurricane 

Katrina (2005). Further modeling showed that increasing the rate of population growth in a refuge, 

like interior dunes after a hurricane, would have a much larger impact on population persistence than 

increasing the rate of recovery of damaged habitat, like foredunes after a hurricane. Yuro (2011) 

studied Hurricanes Ivan and Katrina and showed that the Alabama beach mouse has the ability to 

survive hurricanes if they are not successive. Therefore, the expected cumulative impacts of strong 

hurricanes is negligible.

When considering the cumulative impacts from both OCS oil- and gas-related and non-OCS 

oil- and gas-related sources, the impacts to beach mice would be negligible to major; however, the 

incremental contribution of a proposed action would be negligible. 

4.9.3.2.4 Incomplete or Unavailable Information

BOEM has determined that there is no incomplete or unavailable information regarding the 

listed beach mice relevant to the potential impacts from a proposed action or alternatives, and no 

such information was essential to a reasoned choice among alternatives. BOEM used existing 

information and reasonably accepted scientific methodologies to extrapolate from available 

information on beach mice in completing the relevant analysis of impacts.

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

An impact from the OCS oil- and gas-related routine activities associated with a proposed 

action (i.e., proposed regionwide lease sale) on the Alabama, Choctawhatchee, St. Andrew, and 

Perdido Key beach mice is possible but unlikely.

The oiling of beach mouse populations caused by one or more of the reasonably foreseeable 

accidental events as a result of a proposed action could result in local extinctions. Oil-spill response 
Description of the Affected Environment and Impact Analysis 4-341

and cleanup activities could also have a substantial impact to beach mice and their habitat if all 

cleanup personnel are not adequately trained to avoid areas where beach mouse burrows are 

present. However, potential spills that could result from OCS oil- and gas-related activities are not 

expected to contact beach mice or their habitats. Impacts may result from ingestion or entanglement 

in beach trash and debris that could be accidentally lost, despite mitigations typically applied through 

the lease and NTLs. Because OCS oil- and gas-related routine activities would deposit only a small 

portion of the total debris that would reach the habitat, the impacts related to a proposed lease sale 

under Alternative A would be negligible. A review of the available information shows that 

reasonably foreseeable impacts on beach mice from accidental impacts associated with OCS 

oil- and gas-related activities would be negligible. 

Cumulative activities have the potential to harm or reduce the numbers of the four listed 

subspecies of beach mouse. Those activities include oil spills, alteration and loss of habitat, 

predation and competition, ingestion and entanglement in beach trash and debris, and natural 

catastrophes (hurricanes and tropical storms). Most spills that may occur as a result of the proposed 

activities are not expected to contact beach mice or their habitats because they use areas above the 

intertidal zone where contact is less likely. Within the last 30-40 years, the combination of habitat 

loss due to beachfront development, the isolation of remaining beach mouse habitat areas and 

populations, and the destruction of remaining habitat by tropical storms and hurricanes have 

increased the threat of extinction of several subspecies of beach mice. Given these other 

cumulative factors and their relative impacts on the beach mouse and their habitat, the expected 

incremental contribution of OCS oil- and gas-related activities from a proposed lease sale under 

Alternative A to the cumulative impacts is negligible. 

4.9.3.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of this alternative would be the same as those identified in Alternative A, as 

portions of the proposed lease sale area under both alternatives (i.e., the CPA/EPA) are near beach 

mouse habitat. Reasonably foreseeable impacts are expected to be negligible for the reasons 

provided under Alternative A. The beach mouse subspecies included in the analysis are distributed 

across coastal Alabama and the Florida panhandle, and are adjacent to the EPA and CPA.

4.9.3.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

The impacts of Alternative C would yield negligible impacts to beach mice as a result of any 

new leases in the WPA and related Gulfwide postlease activities since the subspecies distributions 

are limited to coastal Alabama and the Florida panhandle as described in Alternative A.
4-342 Gulf of Mexico Multisale EIS

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

The impacts of this alternative would be the same as those identified in either Alternative A, 

B, or C because the Topographic Features, Live Bottom (Pinnacle Trend), and Blocks South of 

Baldwin County, Alabama, Stipulations do not directly affect the beach mouse or its habitat and 

because of the small number of blocks subject to these stipulations and their distance from beach 

mice habitat. Reasonably foreseeable impacts would be negligible.

4.9.3.2.9 Alternative E—No Action

If a proposed lease sale does not occur, then there would be no additional impacts to beach 

mice as there would be no lease sale held, thus leading to no new impacts from OCS oil- and gasrelated activities resulting from a lease sale. There would be no incremental contribution to 

cumulative impacts on the species or habitat; however, other past lease sales, postlease activities 

related to previous lease sales, or other authorized OCS oil- and gas-related activities may continue 

and have an incremental increase on the impacts on these subspecies of beach mouse. The 

cumulative impacts from both OCS oil- and gas-related and non-OCS oil- and gas-related sources 

would remain the same.

4.9.4 Protected Birds

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

with a GOM proposed action and a proposed action’s incremental contribution to the cumulative 

impacts to ESA-listed birds are presented in this chapter. The approach of the analysis is to focus 

on the potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., 

exploration, development, and production), as well as accidental events and cumulative impacts, 

and to define impact-level measures for each impact-producing factor (refer to Table 4-18 in 

Chapter 4.9).

4.9.4.1 Description of the Affected Environment

The protected birds analyzed in this Multisale EIS include those species that use the OCS or 

coastal counties/parishes along the Gulf of Mexico during any part of their lifecycle and are listed 

under the Endangered Species Act as threatened or endangered. Other species that met these 

criteria were excluded if their habitats were more upland or away from the coast (Appendix F). All 

of the following protected bird species are also protected under the Migratory Bird Treaty Act. The 

impact-producing factors that could affect protected birds are outlined in Table 4-18 in Chapter 4.9. 

A review of a description of associated impact-producing factors for these species is discussed in 

detail and can be referenced from Chapter 4.8 (Birds). However, similar impact-producing factors 

that may affect protected species may have greater impacts to protected species and their 

associated critical habitat due to their small population size and ESA-listing status. Those impacts 

are considered in the following analysis.
Description of the Affected Environment and Impact Analysis 4-343

The habitats of the protected bird species described in this Multisale EIS vary from upland 

habitat, freshwater wetlands, estuarine, coastal beaches, and tidal flats to offshore migration and 

foraging; impacts to the physical aspects of the coastal habitats are identified in Chapter 4.3

(Coastal Habitats). Critical habitat status is presented at the beginning of each species description 

below and geographically in Figure 4-25. 

Collectively, the bird species included in this analysis are distributed across the GOM region 

from southern Florida to eastern Texas as year-round residents or migratory with a strong seasonal 

component. Many of the migratory bird species are less abundant along the GOM during the 

season when they are on their breeding grounds and have higher densities and/or wider distributions 

during migration and non-breeding season.

Cape Sable Seaside Sparrow

Cape Sable seaside sparrow (Ammodramus maritimus mirabilis) is a small, resident species 

that was originally federally listed as endangered on March 11, 1967. A South Florida Multi-Species 

Recovery Plan was completed on May 18, 1999. A Five-Year Status Review was completed on 

August 18, 2010, indicating continued declines and no change to its status. A final rule for critical 

habitat designations was issued in 2007 (Federal Register, 2007). The average estimated 

population size for all six subpopulations from 2005 to 2009 was 3,021 individuals (USDOI, FWS 

2010b). In 2014, a range-wide survey indicated that the population had declined to 2,720 individuals 

(Beerens et al., 2016).

It is associated with marl prairie and ephemeral wetlands, and is distributed in six small 

isolated populations in southern Florida, including Collier, Miami-Dade, and Monroe Counties along 

the Gulf Coast within Everglades National Park and Big Cypress National Preserve. These 

populations are located in areas where OCS oil- and gas-related activities would rarely occur, if at 

all. Habitat loss and fragmentation through hydrologic alteration from wetland drainage, tilling, 

diking, controlled burns, agriculture activities, and commercial and private development in its 

preferred habitat are likely the primary causes for its original listing. The species appears to have 

highly variable nest success and survival (Boulton et al., 2009), which is problematic for a species 

with such low population numbers. Overall, this population appears to be limited by available 

nesting habitat and the “normal” onset of summer rains that result in decreased productivity later in 

the nesting season (Nott et al., 1998; Elderd and Nott, 2008) rather than restricted dispersal due to 

fragmented habitat (Van Houtan et al., 2010).

Piping Plover

Two populations of piping plover (Charadrius melodus) winter along the Gulf Coast and are 

recognized under the ESA: the Great Lakes (endangered) and the Great Plains (threatened) 

populations (Federal Register, 1985). The Great Plains population breeds primarily along the 

Missouri River system and its tributaries, as well as alkali wetlands and lakes in the Dakotas, 

Montana, and in prairie Canada; this population winters primarily along the GOM (Haig et al., 2005; 

Roche et al., 2010). The Great Lakes population breeds primarily along the shores and cobble 
4-344 Gulf of Mexico Multisale EIS

beaches and associated islands with similar substrate in the Great Lake States and Canadian 

provinces (Stucker et al., 2010); the population winters primarily along the south Atlantic Coast with 

the greatest densities between St. Catherine’s Island, Georgia, and Jacksonville, Florida, but it can 

be found as far west as the Laguna Madre, Texas (Stucker and Cuthbert, 2006; Gratto-Trevor et al., 

2009). As much as 75 percent of all breeding piping plovers may winter along the GOM, spending 

up to 8 months on the wintering grounds (February-October).

The latest Five-Year Review was published on September 29, 2009, with recommendations 

that their statuses remain unchanged. Habitat loss and degradation due to commercial, residential, 

and recreational developments on both breeding and wintering areas is the likely cause for declines. 

The piping plover is considered a State Species of Conservation Concern in all Gulf Coast States. 

The piping plover population estimates indicate declines for at least two of three populations at their 

breeding grounds (Great Lakes and Atlantic) (Haig et al., 2005; Roche et al., 2010).

In order to protect migratory birds, it is important to consider all seasonal habitats in the area 

of potential impacts that are used during the life cycle of the species. The habitats used by wintering 

birds along the GOM include beaches, mud flats, sand flats, algal flats, and washover passes (areas 

where breaks in the sand dunes result in an inlet). Wintering plovers are dependent on a mosaic of 

habitat patches and move among these patches depending on local weather and tidal conditions. It 

has been hypothesized that, because of habitat attributes (i.e., foraging and roosting opportunities), 

specific wintering habitat may attract the largest concentrations of piping plovers because of a 

preferred prey base and/or because the substrate color provides protection from aerial predators 

due to cryptic and camouflage color (Nicholls and Baldassarre, 1990).

Rufa Red Knot

The rufa red knot (Calidris canutus rufa) subspecies is a small, migratory shorebird listed as 

threatened in January 2015 (Federal Register, 2014d). There is currently no established critical 

habitat or recovery plan for rufa red knot.

Three of the six subspecies of red knot occur in North America, all three of which breed in 

the Arctic; the rufa subspecies occurs along the coast of the Gulf of Mexico. The rufa red knot is a 

long distance migrant that traverses the North and South America continents via the Atlantic Coast 

or a mid-continental route, roughly 9,300 mi (15,000 km). During spring and fall migration, it uses 

coastal beaches, bays, tidal flats, salt marshes, and lagoons primarily along the Atlantic and Gulf 

Coasts, which may serve as the final wintering destination for some birds.

Habitats used by red knots in migration and wintering are similar in character. For wintering, 

they generally use coastal marine and estuarine habitats with large areas of exposed intertidal 

sediments. In North America, red knots are commonly found along sandy, gravel, or cobble 

beaches, tidal mudflats, salt marshes, shallow coastal impoundments and lagoons, and peat banks. 

The supra-tidal (above the high tide) sandy habitats of inlets provide important areas for roosting, 
Description of the Affected Environment and Impact Analysis 4-345

especially at higher tides when intertidal habitats are inundated. In wintering and migration habitats, 

red knots commonly forage on bivalves, gastropods, and crustaceans.

Within the GOM region, wintering birds are found primarily in Florida and Texas, but the 

species has also been observed in Louisiana, Alabama, and Florida. The red knot uses salt marsh, 

brackish lagoons, tidal mudflats, mangrove areas, and beach habitats. In Lee County, on Florida’s 

Gulf Coast, during fall migration, the red knot used intertidal substrates on ocean beaches at inlets. 

Along the Texas coast, red knots forage on beaches, oyster reefs, and exposed bay bottoms, and 

they roost on high sandflats, reefs, and other sites protected from high tides.

Based on the best available information, there is currently no precise population estimate for 

this subspecies; however, since 2000, declines of 70-75 percent have been recorded in Tierra del 

Fuego for the wintering birds and in Delaware Bay during the spring migration. Harvesting of 

horseshoe crabs in Delaware Bay has reduced their availability as a major food source near 

Delaware Bay, resulting in negative effects to the population. This is an important source of nutrition 

for the migrating birds that stop to refuel during their transition between wintering and breeding 

grounds. Declines have also been observed in the population that departs the central Canadian 

Arctic in August.

Roseate Tern

The North American subspecies of roseate tern (Sterna dougallii dougallii) is separated into 

two distinct population segments according to the location of the breeding areas: the Northeastern 

population (along the Atlantic Coast from Nova Scotia to North Carolina and Bermuda) fluctuating 

around 3,500 breeding pairs, which is listed as endangered; and the Southeast U.S./Caribbean 

population (including Florida, Puerto Rico, and the Virgin Islands) with between 4,000 and 

5,000 breeding pairs, which is listed as threatened (Gochfeld et al., 1998). Both populations were 

listed on November 11, 1987, due to habitat loss as well as increased competition and predation 

(Federal Register; 1987). Recovery plans for the Northeast and Caribbean populations were 

completed on September 24, 1993, and November 5, 1998, respectively.

The Northeastern population breeds in the northeastern United States and eastern Canada 

(Kirkham and Nettleship, 1987) with migratory routes over the open ocean to the West Indies and 

South America. Migratory information for the Caribbean population is less understood, but 

information for the Florida breeders indicates peak arrival in mid-April to mid-May and peak 

departure in mid-August to mid-September. By the 1990’s, there were two remaining nesting sites in 

Florida: Pelican Shoal and the rooftop of the Marathon Government Building in Monroe County, 

Florida (Zambrano et al., 2000). These sites are in the Florida Keys and far from potential 

interactions from proposed OCS oil- and gas-related activities. In Florida, approximately 

350 breeding pairs are estimated, with 15-225 pairs in the Dry Tortugas (USDOI, FWS, 2010c). 

Terns are seabirds that forage by plunge diving for small fish in coastal and pelagic waters. The 

roseate tern is considered a State Species of Conservation Concern in Florida and is protected by 

the Migratory Bird Treaty Act.
4-346 Gulf of Mexico Multisale EIS

Mississippi Sandhill Crane

The population of Mississippi sandhill crane (Grus canadensis pulla) has a nonmigratory, 

resident population with an extremely limited distribution (Jackson County, Mississippi). This 

subspecies was listed as endangered on June 4, 1973 (Federal Register, 1973b), due to a small 

population size, restricted distribution, habitat loss, and habitat fragmentation (consisting of wet pine 

savanna). This species is presently reproductively isolated and persists primarily due to 

augmentation from a captive-breeding program. In February 2016, there were 129 cranes in the wild 

population; annual reports are provided for updates on FWS’ website (USDOI, FWS, 2016). At 

present, much of its habitat is protected in the Mississippi Sandhill Crane National Wildlife Refuge. 

Three separate critical habitat designations were completed in the 1970’s (Federal Register, 1975, 

1977a, and 1977b). The I-10 corridor jeopardized the existence of this population, but a settlement 

agreement resulted in the Mississippi Department of Transportation purchasing 1,960 ac (793 ha) to 

be set aside as habitat, and an interchange was built (USDOI, FWS, 1991). The Mississippi Sandhill 

Crane National Wildlife Refuge in Jackson County, Mississippi, represents 74 percent of the total 

acres of critical habitat (USDOI, FWS, 1991). 

The sandhill crane feeds primarily on land or in shallow emergent wetlands. In fall and 

winter, Mississippi sandhill cranes roost mainly in the Pascagoula Marsh (Tacha et al., 1992), thus 

making them vulnerable to coastal or offshore oil spills if a spill reached their roosting habitat within 

estuarine marshes.

Whooping Crane

The whooping crane (Grus americana) was federally listed as endangered on March 11, 

1967, primarily due to overhunting and habitat loss (Federal Register, 1967). In 1941, only 

15 whooping cranes remained. Critical habitat (established in 1978) along the Gulf Coast is within 

the Aransas National Wildlife Refuge in Texas (Federal Register, 1978b).

The whooping crane currently exists in the wild as one self-sustaining wild population (i.e., 

the Aransas-Wood Buffalo National Park Population) and the released, experimental, nonessential 

populations including Florida, Louisiana, Wisconsin, Colorado, Idaho, Wyoming, New Mexico, and 

Utah (Federal Register, 2011c). There are 12 captive sites that contribute to the captive breeding 

and release program (USDOI, FWS, 2012). The self-sustaining Aransas-Wood Buffalo population 

spans across Kansas, Montana, Nebraska, North Dakota, Oklahoma, South Dakota, and Texas 

during migration. This includes the only self-sustaining population, i.e., the Aransas-Wood Buffalo 

population, which is estimated at 308 birds from FWS’ 2014-2015 annual survey of their wintering 

grounds in Texas (USDOI, FWS, 2015i). This population nests in Wood Buffalo National Park and 

adjacent areas in Canada, and it winters in coastal marshes in Texas. The majority of the AransasWood Buffalo National Park population migrates down through the Dakotas, Nebraska, Kansas, and 

Oklahoma before arriving on the wintering grounds in the coastal marshes and estuarine habitats in 

the Aransas National Wildlife Refuge in Texas where they typically arrive by late October to 

mid-November and depart in late March to mid-April. As of February 2015, there were 

603 whooping cranes in the total North America wild and captive populations.
Description of the Affected Environment and Impact Analysis 4-347

Whooping cranes have a strong tendency to show site fidelity to previously used locations for 

breeding, migrating, and roosting sites. Preferred roosting habitat includes open areas with sand 

and gravel bars or shallow water in rivers and lakes (Federal Register, 1978b). Coastal Texas, 

where the population winters, has a low probability of impact from proposed OCS oil- and 

gas-related activities.

Wood Stork

The wood stork (Mycteria americana) is the largest breeding wading bird and the only stork 

native to the U.S. The U.S. breeding population of the wood stork was listed as endangered on 

February 28, 1984 (Federal Register, 1984). The species was formally downlisted to threatened on 

July 30, 2014, as a result of a population increase and expansion of the breeding range (Federal 

Register, 2014e). It was originally listed as a result of three potentially interacting factors: loss of 

preferred wetland habitats and associated available nesting sites; lack of protection at nest sites; 

and loss of preferred foraging habitats and/or prey (Brooks and Dean, 2008). The wood stork 

population in the southeastern U.S. appears to be stable or increasing (Borkhataria et al., 2008; 

Brooks and Dean, 2008). The wood stork is considered a State species of Conservation Concern in 

all Gulf Coast States except Louisiana. No critical habitat rules have been published for this 

species.

Its distribution is restricted to freshwater and estuarine wetlands in the southeastern U.S., 

including North and South Carolina, Georgia, Florida, Alabama, Mississippi, and Louisiana, although 

it is no longer considered to breed in the latter three states (Coulter et al., 1999). For more 

information regarding coastal habitats and proposed OCS oil- and gas-related activities, refer to 

Chapter 4.3 (Coastal Habitats). Breeding locations often change annually due to variation in 

wetland conditions and because of the ability of breeding pairs to track resource availability (i.e., 

wetland conditions and food); not all colonies are occupied every year (Kushlan and Frohring, 1986; 

Bryan et al., 2008). Birds located at the northern edge of the breeding range tend to migrate south 

to winter in southern Georgia and Florida (USDOI, FWS, 2007). Though storks breed throughout 

Florida, it appears the center of the traditional breeding range has shifted northward primarily into 

north and central Florida, Georgia, and South Carolina (Kushlan and Frohring, 1986; Ogden et al., 

1987; Rodgers et al., 2008). There is evidence of relatively major post-breeding dispersal with large 

numbers of birds frequently observed in the Mississippi River Valley; some mixing of U.S. and 

Mexican populations may occur (Bryan et al., 2008).

4.9.4.2 Environmental Consequences

This chapter provides detailed information regarding the impact-producing factors from 

routine activities, accidental events, and cumulative impacts from activities described in Chapter 3

and their potential effects that would potentially result from a single lease sale or the alternatives. 

This analysis applies to all considered alternatives. Because of the distribution of the different 

protected bird species in the Area of Interest, the level of impacts would vary for Alternatives A, B, C, 

and D. However, Alternative E, No Action, would only have impacts associated with continuing 

effects from past lease sales and non-OCS oil- and gas-related activities. This chapter will include a 
4-348 Gulf of Mexico Multisale EIS

summary of the potential impacts as they relate to the action alternatives and the protected bird 

species. The analyses of applicable impact-producing factors are the same as those for birds in 

general (refer to Chapter 4.8.2, Birds); however, the resulting level of impact would differ, as defined 

under the protected species impact criteria.

4.9.4.2.1 Routine Activities

The major impact-producing factors associated with routine activities include those that may 

affect birds found in coastal areas, including beaches, wetlands and mudflats, or offshore. For more 

details on impacts to birds in general, refer to Chapter 4.8 (Birds). Also, since many of these birds 

are found in coastal areas, refer to Chapter 4.3.2 (Coastal Barrier Beaches and Associated Dunes) 

for information on impacts from the proposed activities on coastal habitats. The Red Knot, Piping 

Plover, and Roseate Tern are the only protected bird species that may be found offshore during 

migration or foraging. The Mississippi sandhill crane, whooping crane, and wood stork use wetland 

areas that are associated with coastal marshes. The Cape Sable seaside sparrow and roseate tern 

are only in extreme south Florida. The piping plover and rufa red knot use beach and mudflat areas 

across the Gulf of Mexico at suitable wintering and stop-over locations.

Routine impacts include discharges and wastes, air and water quality (Chapters 4.1

and 4.2), structure presence, lighting, noise, and marine debris.

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

the USEPA and BOEM and result in reduced potential impacts. Due to these regulations and the 

associated environmental monitoring, and the fact that the protected birds are spending more time in 

coastal areas away from many of the discharge and waste associated with a proposed action, the 

impacts to protected birds would be negligible. 

Structure presence and lighting could impact bird species from collision and behavioral 

changes that may lead to energy expense or mortality. In the Gulf of Mexico, a study reported that 

many species of songbirds, shorebirds, wading birds, and raptors were involved in collisions or 

circulating events (Russell, 2005). The red knot, piping plover, and roseate tern would be the only 

protected bird species to use the offshore environment since they either migrate across the GOM or 

forage offshore; however, only the knot was detected offshore during Russell’s study. The impacts 

of offshore structures to protected birds would be negligible to moderate since most of the 

protected bird activity is associated with coastal habitats and is not near the offshore structures. 

Moderate impacts would occur if a protected bird species changes its normal migratory behavior due 

to artificial lighting or if there is a collision with a platform.

Operational noise from OCS oil- and gas-related helicopters and vessel traffic (including 

G&G activities) may cause temporary disturbance to any bird that is near the flight path or landing 

areas. Due to the short-term nature of the impact and that many of these birds would not be in the 

area of known flight paths, the impact would be negligible. 
Description of the Affected Environment and Impact Analysis 4-349

4.9.4.2.2 Accidental Events

The major impact-producing factors resulting from accidental events associated with 

proposed OCS oil- and gas-related activities that may affect protected birds include accidental oil 

spills and response efforts. All species of protected birds in the potentially affected area could be 

impacted by an accidental oil spill and response activities. In the case of an accidental oil spill, 

impacts would be negligible to moderate depending on the magnitude of the oil spilled and 

spatiotemporal proximity of such an event to the particular species of protected birds. These impact 

levels would also be related to the response activities associated with oil-spill cleanup efforts. The 

impacts would depend on the seasonal timing related to migration or breeding seasons where birds 

may be absent or present in higher densities. Impacts from oil spill on birds are discussed in 

Chapter 4.8.2 (Birds, Environmental Consequences), but oil spills may have a greater impact on 

protected species due to their ESA listing criteria.

During the Deepwater Horizon explosion, oil spill, and response, there were at least 

100 species of birds directly affected by oil or associated with oil-affected habitats. Due to the timing 

and location of the catastrophic spill, piping plover was the only ESA-listed species reported that 

incurred direct mortality and loss of productivity (Deepwater Horizon Natural Resource Damage 

Assessment Trustees, 2016).

Marine debris produced by OCS oil- and gas-related activities as a result of accidental 

disposal into the water may affect protected birds by entanglement or ingestion. Due to regulations 

prohibiting intentional disposal of items, impacts from accidental release would be negligible to 

moderate. Impacts would be negligible through beach-cleaning efforts to remove debris from 

certain locations and the use of marine debris awareness and prevention measures on the oil and 

gas industry through NTL 2015-BSEE-G03 (formerly NTL 2012-BSEE-G01), which provides 

guidance to industry operators regarding the reduction of trash and debris elimination into the marine 

environment and which informs operators of regulations set by other regulatory agencies (i.e., the 

USEPA and USCG). Implementation of BSEE’s Marine Trash and Debris NTL is required through 

ESA consultation with FWS and is expected to be applied by the oil and gas industry for any 

associated OCS oil- and gas-related activity. Moderate impacts would occur if one of the protected 

bird species has a negative interaction with trash or debris, leading to mortality.

4.9.4.2.3 Cumulative Impacts

The cumulative impacts of the OCS oil and gas program that could affect protected birds are 

impacts to air and water quality, noise, G&G activities, platform presence and lighting, and 

construction. Mortality associated with collision with offshore structures has been reported in the 

Gulf of Mexico (Russell, 2005). Behavioral changes have also been observed with lighting 

associated with offshore structures. Migratory birds may become disoriented with the lights, 

expending energy in excessive circular flight. This can lead to exhaustion and mortality for 

individuals that are already metabolically compromised due to the energy expense of migratory 

flight. Accidental events include oil spills and related cleanup, impacts of which are discussed in 

detail in Chapter 4.8.2 (Birds, Environmental Consequences).
4-350 Gulf of Mexico Multisale EIS

As for non-OCS oil- and gas-related events, State oil- and gas-related activities would have 

the same general impact-producing factors as the OCS oil- and gas-related activities discussed 

above; however, the activities would be in closer proximity to protected bird species’ coastal habitat. 

The Mississippi River watershed contributes nutrients, causing a seasonal population explosion of 

phytoplankton, which creates a hypoxic or anoxic area. This can decrease fauna in the upper water 

column and decrease chances of successful forging for birds, leading to changes in behavior and 

decreased health condition; therefore, impacts are expected to be negligible to moderate. Wetland

and beach loss would continue in the foreseeable future and would have a major impact to protected 

birds. Most of the coastal habitats used by protected birds are regulated and mitigated by different 

Federal and State agencies; however, continued coastal erosion and wetland loss is expected along 

the Gulf of Mexico. As noted earlier, piping plover population estimates indicate declines for at least 

two of three populations at their breeding grounds (Haig et al., 2005; Roche et al., 2010). Emerging 

infectious diseases such as the West Nile virus, Avian influenza, and Newcastle disease may impact 

protected birds, and impacts would be expected to be major if protected species populations were 

affected by such pathogens. Non-OCS impacts overall are expected to be negligible to major

depending on the degree of impact

When considering the cumulative impacts to the protected bird species, the incremental 

contribution to impacts would be negligible from a proposed action. A proposed action would yield 

a much smaller impact proportionately when compared with the impacts from multiple sources as 

noted above.

4.9.4.2.4 Incomplete or Unavailable Information

Incomplete or unavailable information regarding birds (including protected birds) can be 

found in Chapter 4.8.2 (Birds).

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

The impact-producing factors associated with the Alternative A would include all those listed 

above. The impacts from a proposed action could range from negligible to moderate because of 

current and ongoing mitigations (such as the NTL 2012-BSEE-G01, “Marine Trash and Debris 

Awareness and Elimination”) that are in place and applied during postlease activity reviews. 

Moderate impacts are not expected but may occur if a protected bird species suffers mortality as a 

result of encountering marine debris or an accidental oil spill and cleanup activities.

4.9.4.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

The impacts of Alternative B would be the same as Alternative A for all previously specified 

protected bird species, with the exception of the whooping crane with the listed population in Texas 

and outside of the CPA or EPA. Wintering whooping crane critical habitat is near Port Aransas, 

Texas, along a coastal area of the WPA. The expected impacts to the whooping crane would be 

negligible, but the impacts may be moderate in the unlikely event (which is seasonally dependent 
Description of the Affected Environment and Impact Analysis 4-351

Though the listed coral 

species are protected, they 

would experience the same 

types of potential impacts 

from a proposed action as 

other coral species. 

according to the timing of the incident and the presence of the species at the time) of an oil spill in 

the CPA/EPA, if it resulted in the death of at least one bird.

4.9.4.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

The impacts of this alternative would be the same as Alternative A for the species that occur

in the WPA. The Cape Sable seaside sparrow, roseate tern, and the Mississippi sandhill crane are 

not found off Texas; therefore, they would not be impacted by a proposed lease sale in the WPA. 

Existing lease activity in the CPA and EPA and new activity in the WPA could yield negligible to 

moderate impacts. Moderate impacts may occur if a protected bird species is affected by an 

accidental oil spill and/or response. 

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

The impacts of this alternative would be the same as Alternative A, B, or C because these 

stipulations are specific to areas that do not have any impact on ESA-protected bird species or their 

habitats.

4.9.4.2.9 Alternative E—No Action

The impacts of Alternative E would yield no additional impacts to protected birds. There 

would be no additional incremental contribution to the cumulative impacts to ESA-protected bird 

species or their habitats.

4.9.5 Protected Corals

This chapter provides detailed information regarding the 

protected coral species. However, the types of impact-producing 

factors affecting these species are the same as those described 

in Chapter 4.6.1 (Topographic Features); therefore, they are 

only briefly summarized here in the context of protected coral 

species. A wider impact analysis for live bottom habitats (which 

protected corals may inhabit) can be found in Chapter 4.6 (Live 

Bottom Habitats). However, the level of impact from OCS 

oil- and gas-related and non-OCS oil- and gas-related activities differs from those seen in 

Chapter 4.6.1because the protected coral species have smaller population sizes; therefore, the 

impact levels for protected coral species are described in Table 4-18 in Chapter 4.9. 

4.9.5.1 Description of the Affected Environment

Corals in the GOM that are protected under the ESA include those listed in Table 4-17. 

Distribution of the listed species within U.S. Exclusive Economic Zone ranges from the State of 
4-352 Gulf of Mexico Multisale EIS

Florida, Flower Garden Banks National Marine Sanctuary, and the U.S. territories of Puerto Rico, 

U.S. Virgin Islands, and Navassa Island. Critical habitat was designated for the elkhorn (Acropora 

palmata) and staghorn (Acropora cervicornis) coral species by NMFS in 2008 and includes four 

counties in the State of Florida (Palm Beach, Broward, Miami-Dade, and Monroe Counties), as well 

as the U.S. territories of the U.S. Virgin Islands (St. John/St. Thomas and St. Croix) and Puerto Rico 

(Federal Register, 2008c). However, this designated critical habitat is located outside of the GOM 

planning area and is not expected to be affected by a proposed action, as seen in Figure 4-25 in 

Chapter 4.9. Furthermore, the OCS lease blocks in the EPA near these critical habitat areas are not 

being offered in a proposed lease sale due to the current leasing moratorium and are therefore too 

distant to be reasonably affected by routine activities or accidental events. Though the listed 

species are protected, they would experience the same types of potential impacts from a proposed 

action as other coral species. For a detailed description and impact analysis of coral habitats in the 

GOM, refer to Chapter 4.6. 

Elkhorn coral and staghorn coral were listed as threatened under the ESA in 2006 (Federal 

Register, 2006c). Both corals naturally occur on spur and groove, bank reef, patch reef, and 

transitional reef habitats, as well as on limestone ridges, terraces, and hard bottom habitats 

(Goldberg, 1973; Gilmore and Hall, 1976; Cairns, 1982; Davis, 1982; Jaap, 1984; Wheaton and 

Jaap, 1988; Miller et al., 2008). During the 1970’s and 1980’s, both elkhorn and staghorn corals 

underwent swift declines in abundance throughout their ranges. Although data suggest that whiteband disease, a disease that affects acroporid corals and is distinguishable by the white band of 

dead coral tissue that it forms, was the primary cause of initial decline in Atlantic/Caribbean elkhorn 

and staghorn coral abundances, other threats, such as elevated seawater temperatures, ocean 

acidification, and physical damage from hurricanes, are credible and potentially significant 

impediments to recovery of these species (USDOC, NMFS, 2015i). Additionally, anthropogenic 

physical damage (e.g., vessel groundings, anchors, divers, and snorkelers), coastal development, 

competition, and predation were deemed by NMFS to be moderate threats to both corals in the 

recent recovery plan (USDOC, NMFS, 2015i).

Although the majority of elkhorn coral distributions are outside of the proposed lease sale 

area, a single colony was discovered on the West Flower Garden Bank in 2001 and was still present 

in 2004 (Aronson et al., 2005). This colonization event could potentially represent the early stages 

of a range expansion of Atlantic acroporids related to global warming (Precht and Aronson, 2004), 

but there are currently no long-term data that analyze and test a definitive range expansion. 

Because this colony of elkhorn coral is located in the Flower Garden Banks National Marine 

Sanctuary, this species is considered for the following impact analysis. Staghorn coral was scoped 

out for this analysis because known distributions of staghorn coral do not occupy any areas that are 

being offered in a proposed lease sale and are too distant to be reasonably affected by routine 

activities or accidental events occurring in leased areas. (Refer to Appendix I for list of species not 

considered further because they are unlikely to be affected by the proposed activities.)

On September 10, 2014, the Federal Register published a final rule listing the boulder star 

coral (Orbicella franksi), lobed star coral (Orbicella annularis), and mountainous star coral (Orbicella 
Description of the Affected Environment and Impact Analysis 4-353

faveolata) as threatened under the ESA (Federal Register, 2014b). This Orbicella species complex 

occurs in the western Atlantic and greater Caribbean, including the Flower Garden Banks. It has 

historically been a dominant component on Caribbean coral reefs, characterizing the so-called 

“buttress zone” and “annularis zone” in the classical descriptions of Caribbean reefs. The species 

complex has also become the major reef-builder in the greater Caribbean since the die-off of 

Acropora spp. (USDOC, NMFS, 2015i).

The species complex has high susceptibility to negative impacts from ocean warming, 

acidification, disease, sedimentation, and nutrients; some susceptibility to trophic effects of fishing 

and sea-level rise; and low susceptibility to predation (USDOC, NMFS, 2015i).

Between 1999 and 2009, overall cover of the Orbicella species complex in the Florida Keys 

declined, but it differed by habitat type (Ruzicka et al., 2013). Percent cover declined on the deep 

and shallow fore-reefs but remained stable on patch reefs (Ruzicka et al., 2013). In 2010, a coldwater bleaching event occurred in the Florida Keys where water temperatures dropped into the 

upper 40’s and lower 50’s, which is about 20 oF (-7 oC) lower than the typical temperatures in the 

upper 60’s (USDOC, NMFS, 2015i). This event reduced cover of the Orbicella species complex 

from 4.4 percent to 0.6 percent on four patch reefs in the upper and middle Florida Keys. However, 

the areas in the Florida Keys where the cold-water bleaching event occurred are not being offered in 

a proposed lease sale and are too distant to be reasonably affected by routine activities or 

accidental events occurring in leased areas.

Random surveys in the Flower Garden Banks between 2002 and 2006 found that the 

Orbicella species complex (predominantly O. franksi) was the dominant coral, comprising between 

27 and 40 percent benthic cover (Hickerson et al., 2008). Coral reef systems in the Flower Garden 

Banks are relatively well studied due to the long-term coral reef monitoring program that was 

established in 1989. A more recent study that analyzed mean coral cover at the East Flower Garden

Bank and West Flower Garden Bank from 1989 through 2014 found similar results to Hickerson 

et al. (2008), with the Orbicella species complex being the dominant coral with the greatest mean 

percent cover (31.8%) (Johnston et al., 2016).

4.9.5.2 Environmental Consequences

Some activities as a result of a proposed lease sale have the potential to impact protected 

coral habitat within the GOM. Because of the similarity and overlap of the effects of many activities 

that occur in the OCS, the relevant impact-producing factors considered for protected corals can 

result from bottom-disturbing activities (i.e., routine activities and accidental events) and the potential 

accidental release of drilling muds and contaminants. Chapter 4.6.1 (Topographic Features and 

Associated Communities) provides further detail on the other impact-producing factors that were 

considered but eliminated from further analysis and why.
4-354 Gulf of Mexico Multisale EIS

4.9.5.2.1 Routine Activities

Potential routine impact-producing factors on protected corals are the same as those 

analyzed and described in Chapter 4.6.1 (Topographic Features and Associated Communities). 

Impacts resulting from both routine activities and accidental events are mitigated through the 

Topographic Features Stipulation. Protective measures are detailed in NTL 2009-G39. The sitespecific survey information and distancing requirements required during postlease reviews would 

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

potential harm by proposed OCS oil- and gas-related activities. Further, it is believed that most, if 

not all, of the protected corals either occur in the Flower Garden Banks National Marine Sanctuary, 

an area currently excluded from future leasing, or else occur far from the area of proposed activities 

in shallow waters under the jurisdiction of the State of Florida or the U.S. territories named above. 

Moreover, the OCS portions of the EPA that are adjacent to Florida State waters are currently 

excluded from any leasing by a Congressional moratorium in effect through at least 2022. Assuming 

adherence to all expected lease stipulations and other postlease, protective restrictions and 

mitigations, along with site-specific reviews of proposed activities, the routine activities related to a 

proposed action are expected to have negligible impacts.

4.9.5.2.2 Accidental Events

While accidental events have the potential to cause severe damage to specific coral

communities, the number of such events is expected to be small. Impacts resulting from bottomdisturbing activities, as described under “Routine Activities” in Chapter 4.6.1 (Topographic Features

and Associated Communities), are largely the same for accidental events. If a small spill occurs 

close to a protected coral community, those communities may become smothered by the particles 

and exposed to hydrocarbons, which have the potential to severely impact protected corals via 

mortality, loss of habitat, change in community structure, and failed reproductive success. Beyond 

the area of spilled oil, impacts are expected to be less severe as particles are biodegraded and 

become more widely dispersed. Many of the protected corals either occur in the Flower Garden 

Banks National Marine Sanctuary, which is currently excluded from future leasing, or are far from the 

area of proposed activities. Therefore, impacts from reasonably foreseeable accidental events, 

when considering the proximity of the Flower Garden Banks National Marine Sanctuary to leased 

areas, are expected to be negligible short in duration, and limited to the area where the accident 

occurs. A negligible impact would be largely undetectable and may cause slight, localized changes 

to a protected coral species community where recovery from the impact is expected. 

4.9.5.2.3 Cumulative Impacts

Proposed OCS oil- and gas-related activities would contribute incrementally to the overall 

OCS and non-OCS cumulative impacts experienced by corals. A variety of non-OCS oil- and 

gas-related activities, including fishing and anchoring, along with shifting natural conditions such as 

invasive species and climate change, may have a considerable impact on these corals in the future. 

These alternatives would also do little to increase the cumulative impacts since many blocks near 

the features are already leased and non-OCS oil- and gas-related activities are not expected to 
Description of the Affected Environment and Impact Analysis 4-355

decrease. BOEM recognizes these impacts and has determined that a proposed action would not 

increase the cumulative effects on protected corals beyond what they are currently experiencing. 

Overall, impacts from individual OCS oil- and gas-related events are usually temporary, highly 

localized, and expected to impact only small numbers of organisms and substrates at a time, 

particularly since protected corals are distributed in the Flower Garden Banks National Marine 

Sanctuary, which is currently excluded from future leasing, or are far from the area of proposed 

activities. Also, adherence to the expected Topographic Features Stipulation, as well as site-specific 

plan reviews/mitigations, would distance many of these activities, greatly diminishing potential 

effects. Therefore, the incremental contribution of these proposed OCS oil- and gas-related 

activities is expected to have negligible impacts. Impacts of non-OCS oil- and gas-related activities

are expected to range between negligible to major depending on the effects of natural stressors 

such as disease and climate change to a protected coral community. which could cause changes in 

community structure and ecological functioning. As such, the incremental contribution of OCS 

oil- and gas-related activities to the overall cumulative impacts of a proposed action, combined with 

non-OCS oil- and gas-related activities, is expected to be negligible. 

4.9.5.2.4 Alternatives A, B, and C

Under Alternatives A, B and C, the proposed activities would have the same impact levels to 

coral habitats whether they occur in the WPA, CPA, or EPA. While the WPA is a smaller area with 

less projected activity than is proposed for the CPA/EPA (refer to Chapter 3), many of the protected 

corals either occur in the Flower Garden Banks National Marine Sanctuary, which has no leasing, or 

are far from the area of proposed activities. Additional protection is provided through current and 

ongoing mitigations that are restated during postlease activity reviews (Appendix B). Because 

protected corals occur far from the area of proposed activities and are further protected through 

current and ongoing mitigations, impacts from reasonably foreseeable routine activities and 

accidental events are both expected to be negligible. A negligible impact would be largely 

undetectable and may cause slight, localized changes to a protected coral species community where 

recovery from the impact is expected. No mortality or injury to an individual or group would be 

expected to occur. Under Alternative B, a proposed lease sale, which includes the Flower Garden 

Banks National Marine Sanctuary, would not occur in the WPA; therefore, impacts to protected 

corals as a result of a proposed lease sale would not be reasonably foreseeable to occur. There 

would, however, be ongoing cumulative impacts to the resources associated with ongoing OCS 

oil- and gas-related activities resulting from previous lease sales and from non-OCS oil- and gasrelated activities. Development of oil and gas would, in all likelihood, be postponed to a future lease 

sale decision; in that case, the overall level of OCS oil- and gas-related activity would be delayed, 

not reduced, at least in the short term. It would take several cancelled lease sales before there 

would likely be a noticeable decrease in postlease activities from previous oil and gas lease sales.
4-356 Gulf of Mexico Multisale EIS

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

Under Alternative D, should the blocks subject to the Topographic Features and Live Bottom

(Pinnacle Trend) Stipulations be excluded, protected corals would be further protected by distancing 

OCS oil- and gas-related activities farther from these habitats, thereby reducing the probability of 

potential impacts from routine activities or accidental events. Blocks subject to the Topographic

Features Stipulation include any available unleased block in which a No Activity Zone or Shunting 

Zone may be applied. A total of 207 blocks within the CPA and 160 blocks in the WPA are affected 

by the Topographic Features Stipulation. The exclusion of any of the other blocks subject to the 

Blocks South of Baldwin County, Alabama, Stipulation is not expected to change the impacts to 

protected corals because of the small number of blocks and their distance from these corals. For 

additional information related to the specific blocks that would be excluded, refer to Appendix D. 

Because protected corals occur far from the area of proposed activities and are further protected 

through current and ongoing mitigations, impacts from reasonably foreseeable routine activities and 

accidental events are both expected to be negligible because it would be very unlikely that 

protected corals would encounter any impact-producing factor from OCS oil- and gas-related 

activities if the blocks subject to the Topographic Features and/or the Live Bottom (Pinnacle Trend) 

Stipulations are excluded.

4.9.5.2.6 Alternative E—No Action

Under Alternative E, a proposed lease sale would not occur; therefore, no impacts to 

protected corals as a result of a proposed lease sale would occur. There would, however, be 

ongoing cumulative impacts to the resources associated with ongoing OCS oil- and gas-related 

activities resulting from previous lease sales and from non-OCS oil- and gas-related activities. 

Development of oil and gas would, in all likelihood, be postponed to a future lease sale decision; in 

that case, the overall level of OCS oil- and gas-related activity would be delayed, not reduced, at 

least in the short term. It would take several cancelled lease sales before there would likely be a 

noticeable decrease in postlease activities from previous oil and gas lease sales.

4.10 COMMERCIAL FISHERIES

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

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

commercial fisheries are presented in this chapter. The approach of the analysis is to focus on the 

potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., exploration, 

development, and production), as well as accidental events and cumulative impacts, and to define 

the impact-level measures for each impact-producing factor (Table 4-20). The potential magnitude 

of impact for each of these impact-producing factors is provided in Table 4-20 to help the reader 

quickly identify the level of potential impacts for commercial fisheries. The impact-level definitions 

and the analyses supporting these conclusions are then discussed in detail in this chapter. The 

analysis in this chapter relies on the analysis and conclusions reached in Chapter 4.7 (Fish and 
Description of the Affected Environment and Impact Analysis 4-357

Invertebrate Resources). Therefore, in general, the impact-producing factors identified in 

Chapter 4.7 would have the potential to impact commercial fisheries as well.

Impact-Level Definitions

In this chapter, the impact levels are defined in terms of the duration, intensity, and geographical 

extent of the impacts to the human uses of commercial fisheries along the Gulf Coast. Long-term 

impacts are those lasting more than 1 year. Extensive impacts are those for which it is difficult to 

find substitute fishing sources nearby, while severe impacts mostly or completely prevent 

commercial fishing in an area. In particular, the impacts of each impact-producing factor are 

summarized in Table 4-20, using the impact-level definitions below.

• Beneficial – Impacts would be positive. The level of benefical impacts are 

specified in the analysis, which could be low, medium, or high.

• Negligible – Little or no detectable adverse impact.

• Minor – Adverse impacts are detectable but less than severe.

• Moderate – Adverse impacts are severe but are short term and/or not extensive.

• Major – Adverse impacts are long term, extensive, and severe.

Table 4-20. Commercial Fisheries Impact-Producing Factors That Are Reasonably Foreseeable.

Commercial Fisheries Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Activities

Fish Population Negligible to Negligible to Negligible to Negligible to Negligible

Minor Minor Minor Minor

Space-Use Conflicts Negligible to Negligible to Negligible to Negligible to Negligible

Minor Minor Minor Minor

Production Structure 

Emplacement and 

Removal

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible

Minor Minor Minor Minor

Accidental Events

Oil Spills Negligible to Negligible to Negligible to Negligible to Negligible

Minor Minor Minor Minor
4-358 Gulf of Mexico Multisale EIS

Cumulative Impacts

Incremental 

Contribution2

Beneficial to Beneficial to Beneficial to Beneficial to Negligible Minor Minor Minor Minor

OCS Oil and Gas3 Beneficial to

Moderate

Non-OCS Oil and 

Gas4

Beneficial to

Major

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

4.10.1 Description of the Affected Environment 

The Gulf of Mexico is home to a large and complex commercial fishing industry. There were 

$1.027 billion in finfish and shellfish landings in the Gulf of Mexico in 2014, which comprised 

19 percent of total U.S. landings (USDOC, NMFS, 2016c). Some of the most economically 

important commercial fisheries in the Gulf of Mexico are white shrimp (Litopenaeus setiferus), brown 

shrimp (Farfantepenaeus aztecus), eastern oysters (Crassostrea virginica), Gulf menhaden 

(Brevoortia patronus), blue crab (Callinectes sapidus), red grouper (Epinephelus morio), red snapper 

(Lutjanus campechanus), and tunas (Thunnus spp.). Fisheries are managed by NOAA Fisheries 

(NMFS), as advised by the regional fisheries management councils. Commercial fisheries are 

regulated by various mechanisms, including permitting, closures, quotas, and gear restrictions; 

details regarding these mechanisms are described by the Gulf of Mexico Fishery Management 

Council (2015). This source also describes the allowable gear types for each fishery. Some of the 

most common gear types are trawls (for shrimp), purse seines (for menhaden), dredges (for 

oysters), traps (for blue crab), and longlines (for various finfish). The biological aspects of the 

affected environment for the targeted species are discussed in Chapter 4.7.1 (Fish and Invertebrate 

Resources).

Landings Revenues

Panel A of Table 4-21 presents the total landings revenues for key GOM fisheries, while 

Panels B through F present the landings revenues for the key fisheries in each Gulf Coast State 

from 2011 through 2014. There were $1.027 billion in landings revenues in 2014, compared with 

$812 million in 2011, $746 million in 2012, and $944 million in 2013. Fisheries landed offshore of 

Louisiana accounted for the most fisheries revenue in 2014, followed (in descending order) by 

Texas, West Florida, Alabama, and Mississippi. Shrimp species (particularly white shrimp and 

brown shrimp) account for the most landings revenues ($587,986,000 in 2014) in the Gulf of Mexico. 

Shrimp are caught offshore of all states, particularly Texas and Louisiana, in Federal and State 
Description of the Affected Environment and Impact Analysis 4-359

waters. Menhaden accounts for the most pounds (769,943,000 pounds in 2014) landed in the Gulf 

of Mexico (USDOC, NMFS, 2016c). However, because the average price per pound of menhaden is 

much lower than for other species, menhaden landings accounted for the fourth most landings 

revenue ($70,917,000) in 2014. Menhaden is primarily caught in State and Federal waters offshore 

of Louisiana and Mississippi. Oysters ($86,751,000) and blue crab ($73,426,000) accounted for the 

second and third highest landings revenues in 2014. These species are caught in State waters of all 

Gulf Coast States. Red snapper and tunas are primarily caught in Federal waters offshore various 

states. Stone crab (Menippe mercenaria) and Caribbean spiny lobster (Panulirus argus) are 

primarily caught offshore Florida.

Table 4-21. Landings Revenues: Landings Revenue by Species and State.

Panel A: Gulfwide Panel B: Louisiana

Species 2011 2012 2013 2014 Species 2011 2012 2013 2014

Shrimp 441,384 390,464 510,486 587,986 Shrimp 133,670 125,587 182,144 227,318

Oysters 65,273 71,688 76,413 86,751 Menhaden 82,881 60,934 84,951 63,364

Blue crab 48,794 47,984 61,802 73,426 Oysters 41,652 37,832 44,835 61,365

Menhaden 92,855 83,450 95,331 70,917 Blue crab 36,784 38,196 51,566 61,082

Groupers 19,679 23,415 23,396 28,830 Crawfish 9,914 4,998 16,490 13,430

Stone crab 24,521 24,039 24,763 27,135 Red snapper 2,261 2,434 4,824 6,400

Red snapper 11,413 13,565 20,621 23,088 Tunas 3,369 7,752 4,595 4,276

Tunas 5,516 10,516 7,308 6,330 King mackerel 1,594 1,475 1,517 2,299

Total Revenue 811,905 745,822 943,640 1,027,885 Total Revenue 324,123 291,721 403,650 451,371

Panel C: Texas Panel D: West Florida

Species 2011 2012 2013 2014 Species 2011 2012 2013 2014

Shrimp 216,382 180,562 228,768 242,299 Lobsters 35,616 21,136 46,749 50,537

Oysters 12,789 21,302 23,465 19,221 Shrimp 28,456 21,463 28,498 40,714

Red snapper 3,254 4,448 7,324 7,617 Stone crab 24,430 23,934 24,710 27,132

Blue crab 2,845 2,878 2,331 3,050 Red grouper 15,087 16,737 16,219 20,944

Black drum 1,448 1,491 1,699 1,981 Mullets 8,630 5,050 11,081 8,072

Groupers 549 723 1,121 1,128 Red snapper 5,417 6,141 8,073 8,067

Atlantic croaker 622 743 819 681 Blue crab 7,719 5,142 6,454 6,977

Vermillion snapper 1,274 1,434 659 604 Oysters 8,582 9,706 5,783 4,038

Total Revenue 240,566 215,083 267,998 278,353 Total Revenue 166,015 143,188 181,507 203,372

Panel E: Mississippi Panel F: Alabama

Species 2011 2012 2013 2014 Species 2011 2012 2013 2014

Shrimp 18,514 23,844 22,055 15,210 Shrimp 44,361 39,009 49,021 62,445

Menhaden 9,871 22,394 10,230 7,358 Blue crab 1,128 1,044 1,036 1,319

Oysters 928 1,596 1,544 1,685 Mullets 687 1,206 1,178 1,046

Blue crab 318 724 416 997 Spanish 

mackerel 582 1,149 940 472

Red snapper 168 226 NA 307 Oysters 1,322 1,253 786 441

Total Revenue 30,291 49,335 34,953 25,995 Total Revenue 50,910 46,495 55,532 68,793 1

Landings are presented in thousands of dollars.

Source: USDOC, NMFS, 2016c.
4-360 Gulf of Mexico Multisale EIS

Fisheries Supply Chain

The fisheries landings discussed above are brought to shore at various ports along the Gulf 

Coast. Some of the leading commercial fishing ports, along with the fisheries revenues received in 

2014 at these ports, are Empire-Venice, Louisiana ($127.3 million); Brownsville-Port Isabel, Texas 

($76.3 million); Galveston, Texas ($69 million); Dulac-Chauvin, Louisiana ($69 million); Bayou 

La Batre, Alabama ($58.1million); Intracoastal City, Louisiana ($43.3 million); and Port Arthur, Texas 

($40.6 million) (USDOC, NMFS, 2016d). Fish landings then proceed through supply chains that 

include dealers, processors, distributors, markets, and restaurants. The NMFS used economic 

modeling techniques to estimate the supply chain impacts of fisheries landings (USDOC, NMFS, 

2016c). The NMFS’ estimates of the number of jobs and the amount of value-added supported by 

fisheries landings in each Gulf Coast State are listed below. The large impacts in Florida are due to 

its high numbers of seafood importers, wholesalers, distributors, and retailers.

• Texas (33,880 jobs; $ 1,238,477,000)

• Louisiana (44,066 jobs; $1,115,858,000) 

• Mississippi (4,714 jobs; $102,731,000) 

• Alabama (15,069 jobs; $333,185,000)

• Florida (92,858 jobs; $6,135,060,000)

4.10.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

commercial fisheries that would arise from projected activities from a proposed action are analyzed 

in this chapter. While there are some differences in the amount of activities associated with the 

alternatives, many of the impacts associated with the alternatives are similar. Therefore, this 

chapter will describe the impacts that are expected to apply to all alternatives, while any deviations 

from these impact conclusions will be discussed in Chapters 4.10.2.5-4.10.2.9. 

4.10.2.1 Routine Activities

Routine operations (such as seismic surveys [Chapter 3.1.2.1], drilling activities [Chapters 

3.1.2.2 and 3.1.3.1], service-vessel traffic [Chapter 3.1.4.3], and production structure emplacement 

[Chapter 3.1.3.3], and decommissioning [Chapter 3.1.6]) can impact commercial fisheries by 

impacting the fish populations that support commercial fishing or by impacting fishermen’s access to 

those fish populations. The impacts to fish populations that support commercial fishing are 

described in Chapter 4.7, which describes the impacts of anthropogenic sound, bottom-disturbing 

activities, and habitat modification on fish populations. The impacts to commercial fishing from 

routine activities would depend on the types and scales of commercial fishing activities in an 

impacted area, which are discussed in Chapter 4.10.1. Shrimp, menhaden, red snapper, tunas, and 

groupers are the species most often sought by commercial fishermen in Federal waters and would 

therefore be most directly impacted by a proposed action. Disturbances to those populations would 
Description of the Affected Environment and Impact Analysis 4-361

have proportionate impacts on the seafood supply chain. However, since the impacts to fish 

populations from routine OCS oil- and gas-related activities would be negligible or minor

(determined in Chapter 4.7), the corresponding impacts to commercial fisheries would also be 

negligible or minor. This is because disruptions to fish and invertebrate populations would 

proportionately reduce commercial fishing revenues, as well as the impacts on the seafood supply 

chain.

Space-use conflicts with commercial fishing can arise from routine operations such as 

service-vessel traffic, seismic surveys, pipeline emplacement, drilling, and production structure 

emplacement and removals. The nature of space-use conflicts from these activities depend on the 

durations of the activities, as well as the locations and species affected. For example, structure 

emplacement prevents trawling in the associated area and, thus, could impact the shrimp fishery. 

However, the amount of area closed to trawling would be minimal relative to the vast areas where 

shrimp trawling occur (refer to Chapter 3.1.3.4.2). On the other hand, production platforms can 

facilitate fishing for reef fish such as red snapper and groupers. Scott-Denton et al. (2011) present 

observational data regarding the geographic distribution of various reef fish in the Gulf of Mexico, 

where production structure emplacement can enhance commercial fishing. The eventual 

decommissioning of a platform would reverse the effects of structure emplacement unless the 

structure were reefed in place or moved to an artificial reef site. Due to the small scale of a 

proposed action (Chapter 3), the impacts of space-use conflicts and structure emplacement and 

eventual decommissioning are expected to range from beneficial (low) to minor adverse effects. 

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

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

4.10.2.2 Accidental Events

Accidental events, such as oil spills (Chapter 3.2.1), can impact commercial fisheries by 

impacting the fish populations that support commercial fishing activities, by impacting fishermen’s 

access to those fish populations, or by impacting the seafood supply chain. The impacts of oil spills 

on fish populations that support commercial fishing are described in Chapter 4.7. For example, 

Chapter 4.7 describes the impacts of potential sediment displacement due to a spill, as well as the 

potential lethal and sublethal impacts to fish and shellfish species. The corresponding impacts to 

commercial fishing would depend on the size of the oil spill, as well as on the types and scales of 

commercial fishing activities in an impacted area, which are discussed in Chapter 4.10.1. Oil spills 

in Federal waters would be most likely to affect fisheries for coastal or oceanic species (such as 

shrimp, menhaden, reef fish, tunas, and groupers), and accidental spills in State waters would be 

most likely to affect coastal and inshore fisheries (e.g., shrimp, menhaden, oysters, and blue crab). 

Most commercially valuable species in the Gulf of Mexico have planktonic eggs and/or larvae. 

These early life stages are generally more vulnerable to impacts resulting from exposure to oil and 

could be affected if a spill coincides with a spawning event or impacts nursery habitat (e.g., Coastal 

Habitats [Chapter 4.3] or Sargassum and Associated Communities [Chapter 4.5]).
4-362 Gulf of Mexico Multisale EIS

The area surrounding a spill could be closed to commercial fishing for some period of time. 

However, fishing closures would likely be limited in size and duration. Commercial fishermen would 

likely have numerous alternate fishing sites for the duration of a closure. Oil spills can have other 

impacts to the supply or demand of seafood. Greater New Orleans, Inc. (2011) provides information 

regarding how the various impacts to commercial fisheries evolved subsequent to the Deepwater

Horizon oil spill, which provides insights regarding the potential impacts of future spills. For 

example, an oil spill could cause seafood safety concerns, which would reduce the demand for the 

affected species. An oil spill could also cause certain fishermen to stop fishing to participate in the 

cleanup operations or for economic reasons. Carroll et al. (2016) provides additional information 

regarding the short-term impacts of the Deepwater Horizon explosion, oil spill, and response on the 

seafood industry. For example, this report analyzes, both quantitatively and qualitatively, how the 

reductions in fisheries landings due to the Deepwater Horizon explosion, oil spill, and response 

affected the supply chain for each fishery. A large oil spill could have some longer-term impacts on 

commercial fisheries. While long-term impacts to fish populations as a result of past oil spills in the 

GOM have not been described, impacts could be masked by natural variations in populations or may 

not be evident for several years. However, the oil spills that could arise from a proposed action are 

forecast to be small. Therefore, an oil spill would likely have limited impacts on fish populations, as 

well as limited impacts on the supply and demand for seafood. Therefore, the impacts of oil spills 

arising from a proposed action would be negligible to minor. The exact impacts would depend on 

the locations of oil spills, the species affected, the intensity of commercial fishing activity in the 

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

4.10.2.3 Cumulative Impacts

This chapter analyzes the OCS oil- and gas-related and non-OCS-oil-and-gas-related 

cumulative impacts to commercial fisheries. The geographic bounds of the analysis increase from 

site-specific impacts to Gulfwide impacts. The temporal bounds of the analysis correspond to the life 

cycle of activities forecasted to arise from leasing activities (refer to Chapter 3). The cumulative 

impacts to commercial fisheries would be determined by the cumulative impacts to fish and 

invertebrate populations, which are discussed in Chapter 4.7. The impacts to fish and invertebrate 

populations would impact commercial fishing in proportion to the intensity of commercial fishing for a 

particular species in a particular location. The cumulative impacts to commercial fisheries would 

also be determined by other factors that could affect access to fishing sites or that could affect the 

supply and demand for seafood.

OCS Oil- and Gas-Related Impacts

A proposed action would contribute to the impacts from the routine activities and accidental 

events of the overall OCS Program. Chapter 4.7 discusses the cumulative impacts to fish and 

invertebrate populations from OCS oil- and gas-related sound, bottom-disturbing activities (Chapter 

3.3.1.5), and habitat modification. These impact-producing factors could cause displacement, 

physical harm, or fatalities. The associated cumulative impacts to commercial fisheries would be 

determined by the intensity of commercial fishing for each species in an affected area (described in 

Chapter 4.10.1). In particular, impacts to fish populations could lead to decreased fishing landings 
Description of the Affected Environment and Impact Analysis 4-363

and revenues, which would impact jobs and incomes throughout the seafood supply chain. A 

proposed action would also contribute to the space-use conflicts (Chapter 3.3.1.6) and the potential 

for accidental events (which are discussed above) arising from the OCS Program. The installation of 

production structures could enhance reef fish habitat and thus enhance commercial fishing 

opportunities, although the ultimate decommissioning of production structures could negatively 

impact commercial fishing. Finally, the Deepwater Horizon oil spill may still have some lingering 

impacts on commercial fisheries. Long-term impacts to fish populations as a result of past oil spills 

in the GOM have not been described, but impacts could be masked by natural variations in

populations or may not be evident for several years. Chapter 4.10.1 describes that landings 

revenues for most species have generally recovered since the spill.

Overall OCS oil- and gas-related impacts will range from beneficial (medium) to moderate. 

Negative impacts arising from impacts to fish populations, space-use conflicts, and accidental events 

will be greater than for an individual lease sale. The overall number of production structures also 

serves more of a beneficial role for reef fish, although the corresponding decommissioning of these 

structures negatively impact commercial fishing for reef species. The exact impacts would depend 

on the locations of activities, the species affected, the intensity of commercial fishing activity in the 

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

Non-OCS Oil- and Gas-Related Impacts

The non-OCS oil- and gas-related impacts that could have an effect on commercial fisheries

including anthropogenic sound (Chapter 3.3.2.7), habitat modifications, state oil and gas activities 

(Chapter 3.3.2.1), space-use conflicts, severe weather, commercial fishing regulations, and various 

economic forces.

Chapter 4.7 discusses the impacts of anthropogenic sound and habitat modifications on fish 

resources. These effects would impact commercial fishing to the extent that landings of certain 

species were impacted, which would likely occur in proportion to the scale of commercial fishing in 

an area (Chapter 4.10.1).

State oil and gas activities also have impacts on commercial fisheries. For example, State 

oil and gas activities could lead to space-use conflicts with commercial fisheries and could lead to 

accidental events. State oil and gas platforms could also support reef fish populations important to 

commercial fishermen. The nature of these impacts would be similar to those of a proposed action, 

although the affected species may be different. Accidental spills in State waters would most likely 

affect coastal and inshore fisheries due to proximity to the shorelines (e.g., shrimp, menhaden, 

oysters, and blue crab). The early life stages of these targets are generally more vulnerable to oil 

exposure and could be affected if a spill coincides with a spawning event or if a spill impacts nursery 

habitat. For example, oysters and blue crab are primarily located in State waters and thus could be 

impacted by the associated State oil and gas routine and accidental impacts.
4-364 Gulf of Mexico Multisale EIS

Commercial fishermen also encounter space-use conflicts with recreational, commercial, and 

military vessels that temporarily restrict access to fishing areas. Marinevesseltraffic.com (2015) 

provides maps of current and historical vessel traffic in the Gulf of Mexico. There is a large amount 

of vessel traffic in the Gulf of Mexico, particularly near major ports.

Although tropical storms and hurricanes are parts of the natural environment and not 

considered to adversely impact fish populations, severe events could affect various types of 

infrastructure (e.g., vessels, fish houses, and suppliers) that support commercial fishing. Storms 

could also temporarily prevent fishermen from fishing in certain areas.

A proposed action should also be viewed in light of various economic forces affecting 

commercial fisheries. Participants in the GOM seafood industry compete with participants in various 

other domestic and international markets. The USDOC, NMFS (2015j) presents various statistics 

regarding these markets. For example, GOM shrimp competes with a large import market. In 2013,

there were $5.3 billion of shrimp imports into the U.S., $4 billion of which came from Asian countries. 

Demand for GOM seafood is also positively correlated with the overall state of the economy; 

information regarding the expected progression of the economy is presented in Chapter 4.14.2. 

The cumulative impacts to commercial fisheries would also be influenced by the 

management strategies employed by NMFS, the Gulf of Mexico Fishery Management Council, and 

various State agencies. For example, NOAA and the Texas Parks and Wildlife Department annually 

close Federal and State waters to shrimp fishing for 45-90 days in late spring to ensure a healthy 

shrimp population (USDOC, NFMS, 2015k). Fisheries managers also develop strategies for 

species, such as red snapper, that are important to recreational and commercial fishing (USDOC, 

NFMS, 2015l). Finally, the NMFS has published the final rule for mechanisms to manage 

aquaculture in the Federal Gulf of Mexico (Federal Register, 2016g). The NFMS has published a 

programmatic EIS for its Gulf of Mexico aquaculture management plan (USDOC, NMFS, 2009). 

Chapter 3.3.2.6.5 provides more information regarding aquaculture in the Gulf of Mexico.

Overall non-OCS oil- and gas-related impacts to commercial fisheries would range from 

beneficial (high) to major. This wide range reflects the myriad of non-OCS oil- and gas-related 

impacts that could occur over the timeframe of this cumulative analysis. For example, changes in 

economic conditions could noticeably impact the supply or demand for a certain segment of the 

commercial fishing industry. Similarly, major events (such as a hurricane) or major regulatory 

changes could cause major impacts to commercial fisheries. However, regulatory actions and 

economic adjustments would likely eventually stabilize any major shocks to commercial fishing 

activities.

A proposed action would be relatively small when compared with the OCS oil- and gasrelated and non-OCS oil- and gas-related factors discussed above (refer to Chapter 3). Therefore, 

the incremental cumulative impacts of a proposed action relative to these factors would range from 

beneficial (low) to minor adverse impacts. The exact impacts would depend on the locations of 
Description of the Affected Environment and Impact Analysis 4-365

activities, the species affected, the intensity of commercial fishing activity in the affected area, and 

the substitutability of any lost fishing access.

4.10.2.4 Incomplete or Unavailable Information

BOEM has determined that there is incomplete or unavailable information related to 

commercial fisheries. Some of this incomplete or unavailable information relates to fish populations 

that support commercial fishing, which is discussed in Chapter 4.7. For example, there is 

incomplete or unavailable information regarding the long-term impacts of acute and chronic 

exposure to oil on fish and invertebrates that support commercial fishing. This information is 

unavailable because these impacts would only become evident through time. In lieu of the 

incomplete or unavailable information, BOEM used various data sources and studies to estimate the 

affected environment and impacts of OCS oil- and gas-related and non-OCS oil- and gas-related 

activities for commercial fishing. For example, BOEM used the most recent NMFS landings data, as 

well as the information in Carroll et al. (2016). BOEM has determined that the incomplete or 

unavailable information is not essential to a reasoned choice among alternatives because existing 

data sources are sufficient for BOEM to reasonably estimate impacts.

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

The impacts of Alternative A would correspond to the impacts discussed in Chapter 4.10.2. 

Alternative A could affect commercial fisheries by affecting fish populations or by affecting the 

socioeconomic aspects of commercial fishing. The impacts of a proposed action on fish populations 

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

service-vessel traffic can cause space-use conflicts with fishermen. Structure emplacement could 

have positive or negative impacts, depending on the location and species. Accidental events, such 

as oil spills, could cause fishing closures and have other impacts on the supply and demand for 

seafood. However, accidental events that could arise from a proposed action would likely be small. 

Alternative A should also be viewed in light of the overall OCS Program, State oil and gas activities, 

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

strategies. The incremental impacts of Alternative A on commercial fisheries are expected to range 

from beneficial (low) to minor due to the limited scale of a proposed action. The exact impacts 

would depend on the locations of activities, the species affected, the intensity of commercial fishing 

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

4.10.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative B. There are some differences 

(described in Chapter 4.10.1) in the scales of commercial fishing in the CPA/EPA compared with the 

WPA. For example, menhaden and blue crab comprise larger percentages of landings revenues in 

the CPA/EPA (particularly in Louisiana) compared with the WPA. However, the impact conclusions 
4-366 Gulf of Mexico Multisale EIS

for Alternatives A and B are the same because the types of activities that occur in the WPA and the 

CPA are similar and because most offshore oil- and gas-related activities will occur in the CPA.

4.10.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Alternative C entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative C. There are some differences 

(described in Chapter 4.10.1) in the scales of commercial fishing in the CPA/EPA compared with the 

WPA. For example, menhaden and blue crab comprise larger percentages of landings revenues in 

the CPA/EPA (particularly in Louisiana) compared with the WPA. Alternative C would also entail 

significantly less overall activity than Alternative A. However, these differences are not large enough 

to change the range of impact conclusions (discussed above) for Alternatives A and C. However, 

due to the lower levels of OCS oil- and gas-related activities associated with Alternative C than 

Alternative A, the probability that an impact to commercial fishing would be negliglible (rather than 

minor) would be higher for Alternative C.

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

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

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D entails leasing a subset of the area considered in Alternatives A, B, or C by 

making blocks that would normally be subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations unavailable for lease. 

Therefore, the analyses for those alternatives (described above) cover the potential impacts of 

Alternative D. In addition, Alternative D would not exclude large areas to commercial fishing. This is 

particularly true since fishermen would probably not use certain gear types, such as bottom trawls, 

near topographic features for fear of entangling and damage to gear. Therefore, the impact 

conclusions (which are discussed above) remain the same, though there may be a slight offsetting 

effect to commercial fishing in the excluded blocks, as it would reduce any potential conflict with 

OCS oil- and gas-related activities but would similarly prevent the potential for beneficial effects from 

new platforms or other fish attractions in the blocks.

4.10.2.9 Alternative E—No Action

Alternative E would prevent the impacts discussed in Chapter 4.10.2 from occurring. Since 

there is an expansive existing oil and gas industry, Alternative E would cause some economic 

adjustments (refer to Chapter 4.14.2), which could cause negligible impacts to commercial fishing 

activities. For example, Alternative E would cause workers in the oil and gas industry supply chain 

to lose income, which could slightly affect their demand for seafood. Commercial fisheries would still 

be subject to the impacts from the OCS Oil and Gas Program, as well as the impacts from the 

non-OCS oil- and gas-related sources discussed above.
Description of the Affected Environment and Impact Analysis 4-367

4.11 RECREATIONAL FISHING

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

with a proposed lease sale and a proposed lease sale’s incremental contribution to the cumulative 

impacts to recreational fishing are presented in this chapter. The approach of the analysis is to 

focus on the potential impact-producing factors from OCS oil- and gas-related routine activities (i.e., 

exploration, development, and production), as well as the accidental events and cumulative impacts, 

and to define the impact-level measures for each impact-producing factor. The analysis in this 

chapter relies on the analysis and conclusions reached in Chapter 4.7 (Fish and Invertebrate 

Resources). Therefore, in general, the impact-producing factors identified in Chapter 4.7 would 

have the potential to impact recreational fishing as well.

Impact-Level Definitions

In this chapter (and in the analyses of the alternatives), the impact measures are defined in 

terms of the intensity, duration, and geographical extent of the impacts to the human uses of 

recreational fisheries along the Gulf Coast. Long-term impacts are those lasting more than 1 year. 

Extensive impacts are those for which it is difficult to find substitute fishing sources nearby, while 

severe impacts mostly or completely prevent recreational fishing in an area. The impacts of each 

impact-producing factor are summarized in Table 4-22 using the impact-level measures below to 

help the reader quickly identify the level of potential impacts for recreational fishing. The analyses 

supporting these conclusions are then discussed in detail in this chapter.

• Beneficial – Impacts would be positive. The level of benefical impacts are 

specified in the analysis, which could be low, medium, or high.

• Negligible – Little or no detectable adverse impact.

• Minor – Adverse impacts are detectable but less than severe.

• Moderate – Adverse impacts are severe but are short term and/or not extensive.

• Major – Adverse impacts are long term, extensive, and severe.

Table 4-22. Recreational Fishing Impact Producing Factors That Are Reasonably Foreseeable.

Recreational Fishing Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Activities

Anthropogenic Sound Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Bottom-Disturbing 

Activities Negligible Negligible Negligible Negligible Negligible

Space-Use Conflicts Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor
4-368 Gulf of Mexico Multisale EIS

Recreational Fishing Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Production Structure 

Emplacement and 

Removal

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible

Minor Minor Minor Minor

Accidental Events

Oil Spills Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Cumulative Impacts

Incremental 

Contribution2

Beneficial to Beneficial to Beneficial to Beneficial to Negligible Minor Minor Minor Minor

OCS Oil and Gas3 Beneficial to 

Moderate

Non OCS Oil and Gas4 Beneficial to 

Major

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

4.11.1 Description of the Affected Environment

Recreational fishing is a popular pastime in many parts of the Gulf of Mexico. The GOM’s 

extensive estuarine habitats (Chapter 4.3.1), live bottom habitats (Chapter 4.6), and artificial 

substrates (including artificial reefs, shipwrecks, and oil and gas platforms) support several valuable 

recreational fisheries. Fisheries are managed by NOAA Fisheries (NMFS), as advised by the 

regional fisheries management councils. Details regarding the most recent regulatory mechanisms 

relevant to recreational fishing are described by the Gulf of Mexico Fishery Management Council 

(2015). Recreational landings and effort data for Louisiana, Mississippi, Alabama, and Florida are 

provided by NMFS; recreational fishing data for Texas is provided by the Texas Parks and Wildlife 

Department. Although a proposed lease sale is a regionwide lease sale, the data from these two 

sources are presented separately to allow for methodological differences between them. These 

data, along with data on the economic impacts of recreational fishing, are presented in subsequent 

sections. The biological aspects of the affected environment are discussed in Chapter 4.7 (Fishes 

and Invertebrate Resources).

CPA/EPA Catch and Effort Data

The NMFS collects and provides public access to data on recreationally targeted species, 

landings, and angler effort (USDOC, NMFS, 2014). The NMFS provides recreational fishing data for 
Description of the Affected Environment and Impact Analysis 4-369

Louisiana through 2013; therefore, this chapter will present NMFS data through 2013 to allow for 

consistent comparisons among states. The NMFS also publishes annual reports summarizing these 

data and the economic impacts to the Gulf Coast States (USDOC, NMFS, 2016c). Table 4-23

presents data on the number of angler trips taken in Louisiana, Mississippi, Alabama, and West 

Florida from 2008 to 2013. The total number of angler trips in these four states declined from 2008 

through 2010, but then gradually increased from 21 million trips in 2010 to 25.3 million trips in 2013. 

In 2013, there were 15.9 million angler trips in West Florida, 4.7 million angler trips in Louisiana, 

2.9 million angler trips in Alabama, and 1.8 million angler trips in Mississippi. Table 4-23 also breaks 

down these trips by location and mode. The three geographic locations for each state are inland, 

(inshore saltwater and brackish waterbodies), State ocean waters, and Federal ocean waters. The 

three modes of fishing are shore fishing, charter fishing, and private/rental fishing. The last column 

in Table 4-23 present the percentage of recreational fishing in 2013 broken down by location and 

mode. The least amount of recreational fishing occurs in Federal waters, where most OCS oil- and 

gas-related activities occur. In the four states combined in 2013, 59.7 percent of recreational fishing 

occurred in inland waters, 32.7 percent occurred in State ocean waters, and 7.6 percent occurred in 

Federal ocean waters. In 2013, 53.5 percent of recreational fishing occurred on private or rental 

boats, 42.9 percent occurred from shore, and 3.6 percent occurred on charter boats.

Table 4-23. CPA and EPA Effort Data: Angler Trips in the Gulf of Mexico.

Area 2008 2009 2010 2011 2012 2013

% of 

State 

Total in 

2013

Alabama

Shore Ocean 

(< 3 nmi) 249,893 322,126 447,041 603,546 750,159 1,250,811 43.70%

Shore Inland 452,192 449,470 365,234 598,700 461,221 515,982 18.03%

Charter Ocean 

(<3 nmi) 9,967 9,166 8,860 19,874 15,785 20,615 0.72%

Charter Ocean 

(>3 nmi) 38,046 36,259 17,424 48,616 28,340 56,145 1.96%

Charter Inland 7,700 10,656 7,221 6,351 14,536 12,976 0.45%

Private/Rental Ocean 

(<3 nmi) 247,876 131,997 114,816 191,563 137,321 118,801 4.15%

Private/Rental Ocean 

(>3 nmi) 74,074 134,411 69,335 188,994 131,897 278,821 9.74%

Private/Rental Inland 624,197 618,502 656,226 825,821 766,027 608,280 21.25%

Total 1,703,945 1,712,587 1,686,157 2,483,465 2,305,286 2,862,431 

West Florida

Shore Ocean 

(< 9 nmi) 3,076,591 2,688,011 1,610,807 1,982,194 2,199,810 3,745,909 23.49%

Shore Inland 3,704,990 3,793,756 4,034,208 3,862,665 4,016,544 3,191,414 20.01%

Charter Ocean

(<9 nmi) 187,810 196,753 159,317 179,880 242,666 199,908 1.25%

Charter Ocean 

(>9 nmi) 255,300 262,005 203,201 236,088 307,121 322,185 2.02%

Charter Inland 127,801 113,842 98,440 119,826 149,315 161,479 1.01%
4-370 Gulf of Mexico Multisale EIS

Area 2008 2009 2010 2011 2012 2013

% of 

State 

Total in 

2013

Private/Rental Ocean

(<9 nmi) 3,624,073 2,605,196 2,257,349 1,901,217 2,087,991 2,572,325 16.13%

Private/Rental Ocean 

(>9 nmi) 1,242,935 751,869 681,551 500,067 755,470 1,136,161 7.12%

Private/Rental Inland 5,277,665 5,265,888 5,221,323 5,118,740 5,021,267 4,619,920 28.97%

Total 17,497,165 15,677,320 14,266,196 13,900,677 14,780,184 15,949,301

Louisiana

Shore Ocean 

(< 3 nmi) 62,712 38,930 11,664 48,893 152,094 247,502 5.31%

Shore Inland 870,042 730,053 717,006 1,073,035 978,657 1,101,517 23.63%

Charter Ocean 

(<3 nmi) 10,468 3,931 2,762 6,937 3,646 5,058 0.11%

Charter Ocean 

(>3 nmi) 32,805 21,173 8,106 15,742 19,827 15,373 0.33%

Charter Inland 135,915 157,692 68,018 90,057 91,192 101,935 2.19%

Private/Rental Ocean

(<3 nmi) 97,797 81,008 59,347 77,986 116,854 82,512 1.77%

Private/Rental Ocean 

(>3 nmi) 89,859 99,352 11,568 80,952 88,503 65,730 1.41%

Private/Rental Inland 3,320,459 2,995,875 2,984,016 3,182,645 2,685,791 3,041,527 65.25%

Total 4,620,057 4,128,014 3,862,487 4,576,247 4,136,564 4,661,154 

Mississippi

Shore Ocean 

(< 3 nmi) 0 143 0 0 811 0 0.00%

Shore Inland 359,438 309,612 596,544 760,788 947,075 763,983 43.39%

Charter Ocean 

(<3 nmi) 4,286 2,803 904 3,123 1,628 2,190 0.12%

Charter Ocean 

(>3 nmi) 718 330 949 221 125 153 0.01%

Charter Inland 8,229 7,656 4,989 7,891 9,738 8,911 0.51%

Private/Rental Ocean 

(<3 nmi) 12,056 16,962 12,419 18,682 4,116 6,124 0.35%

Private/Rental Ocean 

(>3 nmi) 28,007 26,316 4,626 12,974 41,137 53,886 3.06%

Private/Rental Inland 555,951 715,505 612,162 811,711 945,819 925,512 52.56%

Total 968,685 1,079,327 1,232,593 1,615,390 1,950,449 1,760,759 

Gulf of Mexico Total CPA and EPA Effort Data

Shore Ocean 

(< 3 nmi) 3,389,196 3,049,210 2,069,512 2,634,633 3,102,874 5,244,222 20.78%

Shore Inland 5,386,662 5,282,891 5,712,992 6,295,188 6,403,497 5,572,896 22.09%

Charter Ocean 

(<3 nmi) 212,531 212,653 171,843 209,814 263,725 227,771 0.90%

Charter Ocean 

(>3 nmi) 326,869 319,767 229,680 300,667 355,413 393,856 1.56%

Charter Inland 279,645 289,846 178,668 224,125 264,781 285,301 1.13%

Private/Rental Ocean 

(<3 nmi) 3,981,802 2,835,163 2,443,931 2,189,448 2,346,282 2,779,762 11.02%
Description of the Affected Environment and Impact Analysis 4-371

Area 2008 2009 2010 2011 2012 2013

% of 

State 

Total in 

2013

Private/Rental Ocean 

(>3 nmi) 1,434,875 1,011,948 767,080 782,987 1,017,007 1,534,598 6.08%

Private/Rental Inland 9,778,272 9,595,770 9,473,727 9,938,917 9,418,904 9,195,239 36.44%

Total 24,789,852 22,597,248 21,047,433 22,575,779 23,172,483 25,233,645 

Source: USDOC, NMFS, 2016c.

Table 4-24 presents data on the most commonly landed species by recreational fishermen in 

Louisiana, Mississippi, and Alabama combined from 2008 to 2013. Landings data for these states 

are presented separate from data for West Florida since most OCS oil- and gas-related activities will 

occur offshore of Louisiana, Mississippi, and Alabama. Some of the most popular recreational 

species in these states are spotted seatrout (Cynoscion nebulosus), red drum (Sciaenops ocellatus), 

Atlantic croaker (Micropogonias undulatus), sand seatrout (Cynoscion arenarius), Spanish mackerel 

(Scomberomorus maculatus), and black drum (Pogonias cromis). In 2013, landings of most species 

were similar to landings observed in prior years. However, there were noticeable increases in 

landings of red drum, black drum, red snapper, and Spanish mackerel; sand seatrout landings were 

lower in 2013 than had been observed in prior years. Dolphin landings decreased from 96,899 in 

2008 to much lower levels from 2009 through 2012, and then increased to 31,524 in 2013.

Table 4-24. CPA and EPA Catch Data: Number of Fish Species Caught by Recreational Anglers from 

2008 through 2013 in Louisiana, Mississippi, and Alabama Combined.

Species/Year 2008 2009 2010 2011 2012 2013

Atlantic Croaker 4,648,460 4,696,500 4,907,698 7,461,690 4,757,605 4,562,458

Black Drum 1,819,040 1,645,416 1,544,695 1,768,605 1,629,633 2,472,942

Blackfin Tuna 57,274 59,046 1,793 33,008 64,007 35,705

Cobia 31,484 21,575 3,519 50,263 25,105 40,448

Dolphins 96,899 7,200 2,174 911 9,418 31,524

Gag 45,383 42,835 10,274 13,523 12,939 20,573

Gray Snapper 233,841 255,943 33,479 142,062 451,724 375,596

Great Amberjack 29,728 28,422 16,982 56,163 15,962 30,410

King Mackerel 35,373 82,508 38,069 70,898 124,839 124,211

Little Tuny 18,529 9,520 14,175 28,660 40,005 17,172

Pinfishes 474,606 454,356 521,732 1,460,956 1,101,630 1,227,257

Red Drum 7,292,431 6,467,215 7,486,800 6,809,940 6,305,267 9,009,223

Red Grouper 12 774 2,296 0 168 2,326

Red Snapper 905,870 894,732 368,901 851,662 607,516 1,743,402

Sand Seatrout 4,052,323 5,294,998 5,715,702 7,115,540 5,194,418 3,768,286

Sheepshead 1,643,546 1,422,352 1,183,531 1,966,957 1,163,684 1,334,601

Southern 

Flounder 557,809 825,776 982,237 964,675 1,016,969 1,320,715

Southern Kingfish 1,350,161 1,190,382 1,045,644 1,075,935 760,688 1,180,114

Spanish Mackerel 196,011 200,662 397,247 541,435 844,101 2,525,453
4-372 Gulf of Mexico Multisale EIS

Species/Year 2008 2009 2010 2011 2012 2013

Spotted Seatrout 24,013,172 21,657,958 15,118,683 19,843,879 20,452,196 22,327,595

Striped Mullet 322,245 293,375 866,308 1,412,632 1,163,763 1,623,070

White Grunt 0 1,084 0 0 0 0

Source: USDOC, NMFS, 2016c.

Table 4-25 presents data on the species most commonly landed by recreational fishermen in 

West Florida from 2008 to 2013. These species include pinfish (Lagodon rhomboides), spotted 

seatrout, gray snapper (Lutjanus griseus), Spanish mackerel, white grunt (Haemulon plumieri), and 

red grouper (Epinephelus morio). In 2013, landings of most species were similar to landings 

observed from 2008 through 2012. However, there were noticeable increases in landings of 

dolphins, gray snapper, and Spanish mackerel; there were noticeable decreases in landings of sand 

seatrout and spotted seatrout.

Table 4-25. CPA and EPA Catch Data: Fish Species Caught by Recreational Anglers from 2008 

through 2013 in West Florida.

Species/Year 2008 2009 2010 2011 2012 2013

Atlantic Croaker 372,271 333,201 429,614 488,456 468,451 437,425

Black Drum 156,391 125,064 218,938 115,842 112,817 219,579

Blackfin Tuna 80,613 25,933 30,354 20,821 44,190 56,765

Cobia 128,670 64,532 58,880 59,124 69,045 71,391

Dolphins 543,588 394,692 267,944 455,918 359,146 1,922,167

Gag 4,511,351 2,926,723 2,250,467 1,255,515 1,112,826 1,382,809

Gray Snapper 7,082,879 4,190,312 2,418,388 2,658,705 4,073,840 6,618,012

Great Amberjack 219,182 183,807 365,690 194,791 151,623 327,080

King Mackerel 338,965 591,022 252,995 173,914 242,302 291,727

Little Tuny 185,031 158,836 126,299 173,102 296,492 157,557

Pinfishes 15,637,922 9,422,451 9,893,857 7,390,804 12,258,510 9,675,256

Red Drum 3,017,880 1,665,659 2,231,738 3,182,220 2,713,322 2,560,823

Red Grouper 3,105,147 3,171,464 2,240,450 2,009,532 2,009,920 3,166,786

Red Snapper 1,883,804 2,046,716 1,400,636 1,189,850 1,408,331 2,322,435

Sand Seatrout 1,282,681 1,337,450 613,338 1,152,573 2,157,703 899,277

Sheepshead 1,412,235 1,489,548 1,700,583 1,882,258 1,805,203 1,608,128

Southern Flounder 37,117 11,332 9,522 23,120 33,346 28,887

Southern Kingfish 240,040 227,140 404,764 87,367 74,894 93,384

Spanish Mackerel 3,742,003 2,938,091 3,643,511 2,934,531 2,434,336 4,986,910

Spotted Seatrout 11,127,967 9,042,259 9,584,787 12,856,960 12,545,581 9,165,609

Striped Mullet 1,083,471 674,022 925,554 801,743 1,395,641 1,555,565

White Grunt 3,721,050 2,283,923 2,494,075 2,852,807 3,405,536 4,701,436

Source: USDOC, NMFS, 2016c.
Description of the Affected Environment and Impact Analysis 4-373

WPA Catch and Effort Data

Table 4-26 provides data on the number of recreational fishing trips in Texas bays, State 

waters, and the Exclusive Economic Zone during each season of 2011-2015 (Fisher, official 

communication, 2016). There were 1,043,098 angler trips in 2015, slightly lower than in prior years. 

The least amount of recreational fishing occurs in Federal waters, where most OCS oil- and gasrelated activities occur. In 2015, 95.3 percent of fishing occurred in bays, 3.2 percent occurred in 

State ocean waters (Texas Territorial Sea), and 1.5 percent occurred in Federal offshore waters. 

Texas divides its data into two fishing seasons: Season A (November 21-May 14) and Season B 

(May 15-November 20). In 2015, 71 percent of angler trips occurred in Season B, and 14 percent of 

trips occurred by charter boats. In recent years, fishing during Season A has been gradually 

declining, while fishing during Season B has been relatively stable.

Table 4-27 provides data regarding the individual species caught by anglers in Texas during 

2011-2015. Panel A presents overall catch data in Texas, while Panels B, C, and D present catch 

data for Texas bays, State waters, and the Exclusive Economic Zone. Consistent with the effort 

data, most recreational fishing catch occurs in bays. The most popular species in bays include 

spotted seatrout, red drum, black drum, and Atlantic croaker. Red snapper (Lutjanus campechanus) 

and king mackerel (Scomberomorus cavalla) are the most popular species in Federal waters. The 

2015 landings of most species were in the ranges observed in prior years. However, landings of 

sand seatrout continued on a downward trend. Landings of Atlantic croaker.were steady from 2011 

through 2013, but then decreased noticeably in 2014, then increased in 2015 to a higher level than 

observed in any of the prior years.

Table 4-26. Texas Effort Data: Number of Angler Trips from 2011 through 2015.

2011

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 330,461 29,842 360,303 576,735 122,855 699,590 907,196 152,6971,059,893

TTS 14,830 4,779 19,609 24,372 2,988 27,360 39,202 7,767 46,969

EEZ 1,424 850 2,274 15,138 1,126 16,264 16,562 1,976 18,538

Total 346,715 35,471 382,186 616,245 126,969 743,214 962,960 162,4401,125,400

2012

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 331,889 87,696 419,585 563,656 134,502 698,158 895,545 222,1981,117,743

TTS 7,563 1,172 8,735 15,375 1,622 16,997 22,938 2,794 25,732

EEZ 1,270 0 1,270 12,668 1,774 14,442 13,938 1,774 15,712

Total 340,722 88,868 429,590 591,699 137,898 729,597 932,421 226,7661,159,187

2013

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 350,918 39,054 389,972 613,508 101,135 714,643 964,426 140,1891,104,615

TTS 5,193 111 5,304 18,559 2,269 20,828 23,752 2,380 26,132
4-374 Gulf of Mexico Multisale EIS

2011

Season A Season B Annual Total

EEZ 989 575 1,564 15,695 1,592 17,286 16,684 2,166 18,850

Total 357,100 39,740 396,840 647,761 104,996 752,757 1,004,861 144,7351,149,597

2014

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 292,988 30,722 323,710 605,314 101,802 707,116 898,302 132,524 1,030,826

TTS 3,550 127 3,677 18,886 2,664 21,550 22,436 2,791 25,227

EEZ 510 0 510 10,403 2,159 12,562 10,913 2,159 13,072

Total 297,048 30,849 327,897 634,603 106,625 741,228 931,651 137,474 1,069,125

2015

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 262,952 36,570 299,522 590,080 104,155 694,235 853,032 140,725 993,757

TTS 4,888 546 5,434 25,294 3,105 28,399 30,182 3,651 33,833

EEZ 62 0 62 12,926 2,520 15,446 12,988 2,520 15,508

Total 267,902 37,116 305,018 628,300 109,780 738,080 896,202 146,896 1,043,098

EEZ = Exclusive Economic Zone; TTS = Texas Territorial Sea

(1) Season A is November 21 - May 14 and Season B is May 15 - November 20.

(2) These data are presented in terms of person-trips. This means that if multiple people go fishing at the same time 

on the same boat that is counted as multiple trips.

Source: Fisher, official communication, 2016.

Table 4-27. Texas Catch Data: Top Species Landed by Recreational Fishermen.

Panel A: Total Landings Panel B: Landings in Bays

Species 2011 2012 2013 2014 2015 Species 2011 2012 2013 2014 2015

Atlantic Croaker 156 157 152 117 213 Atlantic Croaker 154 156 151 117 213

Black Drum 129 256 150 139 127 Black Drum 127 256 150 139 127

King Mackerel 9 9 10 13 8 King Mackerel – – – – --

Red Drum 347 323 269 246 241 Red Drum 344 321 266 245 240

Red Snapper 36 34 47 40 50 Red Snapper – – – – --

Sand Seatrout 226 177 151 146 109 Sand Seatrout 220 169 150 145 108

Sheepshead 57 143 84 39 51 Sheepshead 57 143 84 39 51

Southern 

Flounder 92 96 92 71 85 Southern Flounder 92 96 92 71 85

Spotted Seatrout 1,137 810 795 590 824 Spotted Seatrout 1,119 798 789 585 809

Panel C: Landings in State Waters Panel D: Landings in the Exclusive Economic Zone

Atlantic Croaker 2 1 – – -- Atlantic Croaker – – 1 – --

Black Drum 2 – – – -- Black Drum – – – – --

King Mackerel 5 4 4 6 4 King Mackerel 4 5 6 7 4 

Red Drum 3 2 2 1 1 Red Drum – – 1 – --

Red Snapper 22 21 30 33 34 Red Snapper 14 13 17 7 16
Description of the Affected Environment and Impact Analysis 4-375

Sand Seatrout 5 8 1 1 1 Sand Seatrout 1 – – – --

Sheepshead – – – – -- Sheepshead – – – – --

Southern 

Flounder – – – – -- Southern Flounder – – – – --

Spotted Seatrout 18 11 6 5 14 Spotted Seatrout – 1 – – 1 

(1) Fish landings are presented in thousands of fish.

(2) The TPWD presents data in terms of two seasons: Season A is November 21 - May 14 and Season B is May 15 - 

November 20. Therefore, the annual data reflects combined catch for Seasons A and B. For example, the catch 

data for 2013 reflects catch from November 21, 2012 to November 20, 2013.

Source: Fisher, official communication, 2016.

Economic Impacts of Recreational Fishing

Recreational fishing can affect regional economies in various ways. Most directly, anglers 

affect the economy through spending on fishing-related goods and services. This direct spending 

includes trip expenditures and expenditures on durable equipment. Direct angler spending supports 

firms in related industries along an economy’s supply chain. In addition, spending by fishermen 

serves as income to other actors in an economy, which supports overall spending patterns. The 

NMFS conducted an analysis that quantified this dependence of regional economies on recreational 

fishing activity (USDOC, NMFS, 2016c); this analysis utilized the techniques of an earlier study by 

Gentner and Steinback (2008). These studies utilized input-output economic models, which create 

multipliers that predict the sales, value-added, and jobs that result from direct angler spending. The 

levels of value-added and employment supported by recreational fishing in each Gulf Coast State in 

2014 are listed below.

• West Florida ($4,868,743; 70,109 jobs)

• Louisiana ($1,029,281; 15,241 jobs)

• Texas ($1,205,146; 16,496 jobs)

• Alabama ($827,849; 14,124 jobs)

• Mississippi ($247,281; 4,174 jobs)

4.11.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

recreational fishing that would arise from projected activities from a proposed lease sale are 

analyzed in this chapter. While there are some differences in the amount of activities associated 

with the alternatives, many of the impacts associated with the alternatives are similar. Therefore, 

this chapter will describe the impacts that are expected to apply to all alternatives, while any 

deviations from these impact conclusions will be discussed in Chapters 4.11.2.5-4.11.2.9. 
4-376 Gulf of Mexico Multisale EIS

4.11.2.1 Routine Activities

Routine OCS oil and gas operations (such as anthropogenic sound, bottom disturbances, 

service-vessel traffic, and production structure emplacement) can affect recreational fisheries by 

impacting populations of recreationally targeted species. The impacts of anthropogenic sound and 

short-term bottom disturbances on fish populations are discussed in Chapter 4.7 (Fish and 

Invertebrate Resources). The corresponding impacts of anthropogenic sound on recreational fishing 

would be negligible to minor because disruptions to fish populations could reduce landings in 

proportion to the amount of recreational fishing activities in an area (refer to Chapter 4.11.1). The 

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

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

The OCS oil- and gas-related vessel traffic could also cause space-use conflicts with 

recreational fishermen. The OCS vessel traffic would occur between ports that service the offshore 

industry and drilling and production facilities in Federal waters. However, there is limited spatial 

overlap between recreational fishing and oil and gas ports. In addition, most recreational fishing 

activities in the Gulf of Mexico occur inland or in State waters. Finally, recreational vessels can often 

easily avoid temporary OCS vessel traffic. Therefore, the impacts of OCS oil- and gas-related 

vessel traffic on recreational fishing are expected to be negligible to minor. The exact impacts 

would depend on the locations of activities, the species affected, the intensity of recreational fishing 

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

The impacts of short-term bottom disturbances on recreational fishing are expected to be 

negligible because the impacts to fish populations would similarly be negligible and because most 

recreational fishing does not target bottom-dwelling species that are more likely to be impacted by 

these disturbances. The installation of production platforms can enhance recreational fishing 

opportunities because platforms often attract recreationally important species. Hiett and Milon 

(2002) estimate that 20.2 percent of private boat fishing, 32.2 percent of charter boat fishing, and 

50.9 percent of party boat fishing in Texas, Louisiana, Mississippi, and Alabama combined occur 

within 300 ft (91 m) of an oil or gas structure in State or Federal waters. However, the removal of a 

platform would preclude its use for recreational fishing unless it is redeployed as artificial reef

substrate as part of an artificial reef program (Chapter 3.3.2.1.2). The BSEE presents more 

information regarding the status of Rigs-to-Reefs activities in the Gulf of Mexico (USDOI, BSEE, 

2015f). Ajemian et al. (2015) analyze the fish community structures at operational platforms, 

decommissioned platforms that were reefed using a variety of methods, and Liberty Ships (World 

War II era ships that now serve as artificial reefs) offshore Texas. This study found that 

recreationally important species such as red snapper were prevalent among all types of platform 

structures, suggesting that the reefing of a platform could maintain some of the properties desired by 

recreational fishermen. The structures installed due to a proposed lease sale would likely have 

beneficial (low) to minor impacts on recreational fishing because of the limited amount of activity 

that occurs in Federal waters (Chapter 4.11.1) and because the positive and negative effects of 

routine OCS oil- and gas-related activities that modify habitat (i.e., infrastructure emplacement and 

decommissioning) would partially offset each other.
Description of the Affected Environment and Impact Analysis 4-377

4.11.2.2 Accidental Events

Oil spills can arise from accidents with respect to vessels, pipelines, drilling operations, or 

production operations. The potential impacts of oil spills on fish populations that support recreational 

fishing are described in Chapter 4.7 (Fish and Invertebrate Resources). Oil spills can also lead to 

localized fishing closures that could directly impact fishermen’s access to fish resources. The 

corresponding impacts to recreational fishing would depend on the types and scales of recreational 

fishing activities in an impacted area, which are discussed in Chapter 4.11.1. For example, red 

snapper is a popular recreational species that is prevalent near oil and gas platforms. Therefore, an 

oil spill that occurred near a platform could impact recreational fishing for red snapper and other reef 

fish, at least in the short term. An oil spill could also dissuade anglers if it affected the aesthetics of 

fishing in an area. For example, anglers could be dissuaded by perceived oil in water, tainted fish 

populations, or response activities. Reductions in recreational fishing could also impact the various 

firms that supply goods and services to anglers. Gentner Consulting Group (2010) presents a 

methodology for estimating the economic impacts of an oil spill in the Gulf of Mexico that entails

estimating State-level recreational fishing levels and then scaling these levels by the size and 

duration of a closure area. However, these economic impacts would likely be negligible to minor

because an oil spill arising from a proposed lease sale would likely be small and localized, leaving 

recreational fishermen numerous alternative fishing sites. The exact impacts would depend on the 

locations of oil spills, the species affected, the intensity of recreational fishing activity in the affected 

area, and the substitutability of any lost fishing access. In addition, as shown in the effort and 

landings data above, recreational fishing activity recovered fairly quickly in the aftermath of the 

Deepwater Horizon explosion, oil spill, and response, which was much larger than any reasonably 

foreseeable spill from a proposed lease sale.

4.11.2.3 Cumulative Impacts

A proposed lease sale would contribute to the impacts of the overall OCS Program, as well 

as the impacts of various non-OCS sources. The cumulative analysis will describe these various 

impacts, and will then reach impact conclusions regarding the incremental impacts of a proposed 

lease sale relative to these OCS and non-OCS sources. The geographic bounds of the analysis 

increase from site-specific impacts to regionwide impacts. The temporal bounds of the analysis 

correspond to the life cycle of activities forecasted to arise from leasing activities (refer to 

Chapter 3).

OCS Oil- and Gas-Related Impacts

A proposed lease sale would add to the impacts to fish populations from sound and 

short-term bottom disturbances arising from the overall oil- and gas-related activities of past and 

future lease sales (refer to Chapter 4.7, Fish and Invertebrate Resources). As discussed above, 

these would have impacts to recreational fishing to the extent that angler effort and species’ landings 

are impacted. A proposed lease sale would also add to the space-use conflicts with recreational 

fishermen that arise from the OCS Oil and Gas Program. A proposed lease sale would also add to 

the impacts to recreational fishing resulting from accidental events, such as oil spills, arising from the 
4-378 Gulf of Mexico Multisale EIS

OCS oil- and gas-related activities from past and future lease sales. The scales of these impacts 

are similar as to those discussed above, but they would be proportionally higher to the larger scale 

of the OCS Oil and Gas Program compared with a proposed lease sale.

As discussed above, oil and gas platforms generally enhance opportunities for recreational 

fishing. Conversely, structure removals prevent the use of those structures for recreational fishing. 

The number of platforms in the Federal Gulf of Mexico fell from a peak of 4,049 in 2001 (USDOI, 

BSEE, 2015g) to 2,225 in 2016 (USDOI, BOEM, 2016f), which has reduced opportunities for 

recreational fishing in certain areas. However, anglers still have numerous places to fish, including 

artificial reefs (some of which have been created out of decommissioned platforms) and natural 

habitat features. A proposed lease sale would initially have positive incremental impacts on 

recreational fishing because more structures would be installed than if the lease sale did not occur. 

The eventual removals would offset those impacts unless some structures were maintained through 

Rigs-to-Reefs programs (discussed above and in Chapter 3.3.2.1.2).

Overall OCS oil- and gas-related impacts to recreational fishing will range from beneficial 

(medium) to moderate. Negative impacts arising from impacts to fish populations, space-use 

conflicts, and accidental events will be greater than for an individual lease sale. The overall number 

of production structures also serves more of a beneficial role for reef fishing, although the 

corresponding decommissioning of these structures negatively impacts recreational fishing. 

However, as discussed above, most recreational fishing in the Gulf of Mexico occurs close to shore. 

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

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

Non-OCS Oil- and Gas-Related Impacts

A proposed lease sale would contribute to the impacts of oil and gas activities in State 

waters, which are described in Chapter 3.3.2.1. The nature of these impacts would be similar to 

activities in Federal waters, although the impacts on recreational fishing depend on the intensity and 

species sought in a particular area. As discussed in Chapter 4.11.1, 1.5 percent of recreational 

fishing in Texas occurs in Federal waters, while 7.6 percent of angler effort in the four other Gulf 

Coast States combined occurs in Federal waters.

Recreational fishing in the Gulf of Mexico also encounters space-use conflicts with 

recreational, commercial, and military vessels. Marinevesseltraffic.com (2015) provides maps of 

current and historical vessel traffic in the Gulf of Mexico. There is a large amount of vessel traffic in 

the Gulf of Mexico, particularly near major ports. This vessel traffic causes various localized 

conflicts with recreational fishermen.

Tropical storms and hurricanes can impact boats and other infrastructure that support 

recreational fishing. Recreational fishing would also be negatively affected by wetlands loss or other 

ecosystem degradation. Recreational fishing would also be affected by any impact-producing factor, 

such as a non-OCS oil- and gas-related accidental event, that affects the aesthetics of a particular 
Description of the Affected Environment and Impact Analysis 4-379

fishing site. Recreational fishing would also be positively correlated with general trends in tourism

(discussed in Chapter 4.12, Recreational Resources) and the overall economy (discussed in 

Chapter 4.14.2, Economic Factors). Finally, recreational fishing activity is heavily influenced by 

regulations and artificial reef development (discussed in Chapter 4.11.1).

Overall non-OCS oil- and gas-related impacts to recreational fishing will range from 

beneficial (high) to major. This wide range reflects the myriad of non-OCS oil- and gas-related 

impacts that could occur over the timeframe of this cumulative analysis. For example, hurricanes, 

wetlands loss, or economic developments could cause major impacts to recreational fisheries. 

Similarly, economic developments, artificial reef development, or regulatory changes could 

significantly benefit recreational fishing. However, the most likely case is that regulatory actions and 

economic adjustments will serve to stabilize any major shocks to recreational fishing activities and 

that recreational fishing will occur within the ranges observed in prior years.

Incremental Impacts

Relative to all OCS- oil- and gas-related and non-OCS oil- and gas-related activities, a 

proposed lease sale would have beneficial (low) (due to fish attraction at platforms and the 

potential use of decommissioned platforms as rigs-to-reefs) to minor adverse incremental impacts 

(due to impacts to fish populations, space-use conflicts, and oil spills) on recreational fishing

activities because of the limited amount of activity and because the positive and negative impacts 

would partially offset each other.

4.11.2.4 Incomplete or Unavailable Information

BOEM has identified incomplete or unavailable information regarding the extent to which 

recreational fishing is dependent upon OCS platforms, as well as on the site-specific determinants of 

this dependency. In lieu of this incomplete or unavailable information, BOEM used existing 

information and reasonably accepted scientific methodologies. For example, BOEM used data on 

recreational fishing activity provided by the Texas Parks and Wildlife Department and NMFS to 

examine trends in recreational fishing in various areas. BOEM has also used information from Heitt 

and Milon (2002) and Ajemian et al. (2015), which provide some information on the scale and 

location of platform-dependent recreational fishing. BOEM does not expect the incomplete or 

unavailable information to significantly change its estimates of the impacts of the OCS Program on 

recreational fishing activity because BOEM still has enough baseline data to reasonably estimate 

impacts. Therefore, BOEM has determined that the incomplete or unavailable information is not 

essential to a reasoned choice among alternatives.

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

The impacts of Alternative A would correspond to the impacts discussed in Chapter 4.11.2. 

Namely, a proposed lease sale could affect recreational fishing by affecting fish populations or by 

affecting the socioeconomic aspects of recreational fishing. The impacts of Alternative A on fish 

populations are presented in Chapter 4.7 (Fish and Invertebrate Resources) and include impacts 
4-380 Gulf of Mexico Multisale EIS

due to anthropogenic sound, short-term bottom disturbances, and habitat modifications. Vessel 

traffic arising from Alternative A could cause space-use conflicts with anglers. Structure 

emplacement generally enhances recreational fishing, although this beneficial (low) impact would 

be offset during decommissioning unless a structure was maintained as an artificial reef. Accidental 

events, such as oil spills, could cause fishing closures and affect the aesthetics of fishing in an area. 

However, these impacts would be negligible to minor because the oil spills forecast to arise from a 

proposed action would be small and localized. Alternative A should also be viewed in light of overall 

trends in OCS platform decommissioning, State oil and gas activities, overall vessel traffic, severe 

weather, economic factors, and Federal and State fisheries management strategies. The 

incremental impacts of Alternative A on recreational fisheries are expected to be beneficial (low) to 

minor because of the relatively small scale of a proposed lease sale and because the positive and 

negative effects would partially offset each other. The exact impacts would depend on the locations 

of activities, the species affected, the intensity of recreational fishing activity in the affected area, and 

the substitutability of any lost fishing access.

4.11.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B entails leasing only in the CPA/EPA, which is a subset of the area considered 

in Alternative A. Therefore, the analysis of Alternative A covers the potential impacts of 

Alternative B. There are some differences (described in Chapter 4.11.1) in the types and scales of 

recreational fishing in the WPA compared with the CPA/EPA. For example, 1.5 percent of 

recreational fishing in Texas occurs in Federal waters, while 7.6 percent of recreational fishing in the 

other Gulf Coast States combined occurs in Federal waters. However, these differences are not 

large enough to change the impact conclusions (discussed above) for Alternatives A and B. This is 

because Alternative B entails conducting most of the OCS oil- and gas-related activities proposed 

under Alternative A.

4.11.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Alternative C entails leasing only in the WPA, which is a subset of the area considered in 

Alternative A. Therefore, the analysis of Alternative A covers the potential impacts of Alternative C. 

There are some differences (described in Chapter 4.11.1) in the types and scales of recreational 

fishing in the WPA compared with the CPA/EPA. For example, 1.5 percent of recreational fishing in 

Texas occurs in Federal waters, while 7.6 percent of recreational fishing in the other Gulf Coast 

States combined occurs in Federal waters. In addition, a proposed WPA lease sale would likely lead 

to much fewer oil and gas activities than a proposed regionwide lease sale. However, these 

differences are not large enough to change the range of impact conclusions (discussed above) for 

Alternatives A and C. However, due to the lower levels of OCS oil- and gas- related activities 

associated with Alternative C than Alternative A, the probability that an impact would be negliglible

(rather than minor) would be higher for Alternative C.
Description of the Affected Environment and Impact Analysis 4-381

Recreational resources are 

natural or manmade things 

that are used as part of 

activities that are primarily for 

human enjoyment.

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

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

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D entails leasing a subset of the area considered in Alternatives A, B, or C by 

making blocks that would normally be subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations unavailable for lease. 

Alternative D would not exclude large areas to recreational fishing (refer to Chapter 4.12.1). 

Alternative D would reduce any potential conflict with OCS oil- and gas-related activities, but it would 

prevent the potential for beneficial effects from new platforms or other fish attractions in the blocks. 

Due to the size of the Alternative D blocks relative to the areas in which recreational fishing occurs, 

the range of impact conclusions (which are discussed above) for Alternatives A and D are the same.

4.11.2.9 Alternative E—No Action

Alternative E would prevent the beneficial (low) to minor impacts associated with a proposed 

lease sale, as discussed above. Beneficial impacts of fish attraction to new platforms or 

decommissioned platforms turned into reefs would be negated. Negligible to minor adverse impacts, 

such as space-use conflicts, oil spills, or direct harm to fish populations, would be avoided. Since 

there is an expansive existing oil and gas industry, Alternative E would cause some economic 

adjustments (refer to Chapter 4.14.2), which could cause negligible impacts to recreational fishing

activities. For example, Alternative E would cause workers in the oil and gas industry’s supply chain 

to lose income, which could slightly lessen their propensity to go recreational fishing. However, 

recreational fisheries would still be subject to the impacts from other ongoing activities related to 

previous lease sales under the OCS Oil and Gas Program, as well as the impacts from the non-OCS 

oil- and gas-related sources discussed above.

4.12 RECREATIONAL RESOURCES

This chapter analyzes the potential impacts of routine 

activities and accidental events associated with a proposed 

action on recreational resources, as well as a proposed action’s 

incremental contribution to the cumulative impacts to 

recreational resources. The approach of the analysis is to focus 

on the potential impact-producing factors from OCS oil- and gasrelated routine activities (i.e., exploration, development, and production), accidental events and 

cumulative impacts, and to define the impact-level measures for each impact-producing factor.

Impact-Level Definitions

In this chapter (and in the analyses of the alternatives) the impact measures are defined in 

terms of the intensity, duration, and geographical extent of the impacts to the human uses of 

recreational resources along the Gulf Coast. Long-term impacts are those lasting more than 1 year. 

Extensive impacts are those for which it is difficult to find substitute recreational activities nearby, 

while severe impacts mostly or completely diminish the recreational value of a resource. In 
4-382 Gulf of Mexico Multisale EIS

particular, the impacts of each impact-producing factor are summarized in Table 4-28 using the 

impact-level measures below to help the reader quickly understand the potential impacts of a lease 

sale on recreational resources. The analyses supporting these conclusions are then discussed in 

detail.

• Beneficial – Impacts would be positive. The level of benefical impacts are 

specified in the analysis, which could be low, medium, or high.

• Negligible – Little or no detectable adverse impact.

• Minor – Adverse impacts are detectable but less than severe.

• Moderate – Adverse impacts are severe but are short term and/or not extensive.

• Major – Adverse impacts are long term, extensive, and severe.

Table 4-28. Recreational Resources Impact-Producing Factors That Are Reasonably Foreseeable. 

Recreational Resources Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E 

Routine Activities

Space-Use Conflicts Negligible to Negligible to Negligible to Negligible to Negligible

Minor Minor Minor Minor

Structure Emplacement 

and Removal

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible Minor Minor Minor Minor

Visual Impacts Negligible to Negligible to Negligible Negligible to Negligible Minor Minor Minor

Indirect Econoic 

Impacts

Beneficial to Beneficial to Beneficial to Beneficial to

Negligible Minor Minor Minor Minor

Accidental Events

Oil Spills Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Marine Debris Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Cumulative Impacts

Incremental 

Contribution2

Beneficial to Beneficial to Beneficial to Beneficial to Negligible Minor Minor Minor Minor

OCS Oil and Gas3 Beneficial to

Moderate

Non-OCS Oil and Gas4 Beneficial to

Major

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.
Description of the Affected Environment and Impact Analysis 4-383

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

4.12.1 Description of the Affected Environment

The GOM is home to various resources that support recreational activities. These include 

ocean-based resources as well as resources in counties and parishes along the Gulf of Mexico. The 

overall scales of recreation and tourism are discussed in the following section. The resources that 

support recreational activities are presented in subsequent sections and are organized according to 

the type of recreational resource.

Scales of Recreation and Tourism

Eastern Research Group (2014a) developed methodologies for estimating the amount of 

employment supported by recreation and tourism activities in a particular area. This entailed 

defining which industries comprise recreation and tourism, as well as estimating the percent of each 

industry that supports tourism. For example, the hotel industry is primarily supported by tourists, 

while the restaurant industry is supported by both tourists and local residents. BOEM has identified 

23 Economic Impact Areas (EIAs), which are critical to understanding how a proposed action would 

affect human resources across the Gulf of Mexico (illustrated in Figure 4-29 in Chapter 4.14). 

Table 4-29 presents data on recreational employment, recreational value-added, tourism 

employment, and tourism value-added in the EIAs. Table 4-29 was derived by applying data from 

IMPLAN Group, LLC. (2015) to the methodologies developed in Eastern Research Group (2014a). 

As can be seen, the recreation and tourism industries are sizable in many areas along the Gulf 

Coast. The areas with the largest recreation and tourism industries are TX-3 (which includes 

Houston and Galveston), LA-6 (which includes New Orleans), and various EIAs along the Florida 

coast. Parts of coastal Mississippi and Alabama also have sizeable recreational economies, which 

are supported by parks, beaches, and casinos.

Table 4-29. Recreational and Tourism Employment and Value-Added in BOEM's Economic Impact 

Areas in 2013. 

EIA Recreational 

Employment

Recreational 

Value-Added

Tourism

Employment

Tourism

Value-Added

TX-1 68,769 2,596,402,975 19,081 1,203,931,388

TX-2 48,362 1,868,401,512 15,225 739,484,187

TX-3 366,048 15,331,216,510 123,709 8,466,549,982

TX-4 5,033 188,869,415 1,227 100,190,697

TX-5 18,829 709,291,174 4,763 395,566,972

TX-6 1,417 53,257,782 387 23,864,658
4-384 Gulf of Mexico Multisale EIS

LA-1 14,399 683,645,908 6,149 293,572,508

LA-2 2,799 105,494,355 775 46,049,357

LA-3 32,869 1,315,185,525 9,639 566,173,408

LA-4 17,725 788,255,437 6,269 274,186,740

LA-5 50,188 2,028,801,718 14,122 975,127,188

LA-6 89,036 4,458,755,918 34,493 1,976,234,240

LA-7 23,637 948,326,917 6,577 379,903,898

MS-1 33,103 1,560,781,492 14,167 545,645,437

MS-2 1,475 54,100,278 391 19,098,912

AL-1 37,649 1,274,887,170 10,477 681,999,085

AL-2 3,483 120,034,728 873 73,873,691

FL-1 72,212 2,756,594,208 24,852 1,233,121,800

FL-2 31,357 1,173,072,208 10,300 445,046,333

FL-3 7,954 278,409,013 2,438 114,397,442

FL-4 67,758 2,497,491,474 18,301 1,153,527,693

FL-5 254,735 11,239,013,764 80,319 4,948,465,196

FL-6 115,642 5,472,107,011 45,683 2,263,684,576

State Totals

Texas EIAs 508,457 20,747,439,369 164,393 10,929,587,884

Louisiana EIAs 230,653 10,328,465,778 78,023 4,511,247,338

Mississippi EIAs 34,578 1,614,881,770 14,558 564,744,348

Alabama EIAs 41,132 1,394,921,898 11,349 755,872,776

Florida EIAs 549,658 23,416,687,679 181,891 10,158,243,038

All EIAs 1,364,478 57,502,396,493 450,215 26,919,695,385

EIA = Economic Impact Area.

Sources: Eastern Research Group, Inc.(2014a) and IMPLAN Group, LLC (2015).

Beaches

Beach visitation is one of the most popular activities along the Gulf Coast. The USEPA’s 

“National List of Beaches” (USEPA, 2015e) is an online tool that lists and provides information 

regarding the beaches in any county or parish along the Gulf Coast. Texas and West Florida have 

the most beaches, although there are various beach areas in Louisiana, Mississippi, and Alabama. 

The National Survey on Recreation and the Environment estimates the following number of 

Americans age 16 and older that visited the beaches in each Gulf Coast State annually from 2005 

through 2009: Florida (21,989,300); Texas (4,929,700); Alabama (1,527,900); Mississippi (956,700); 

and Louisiana (578,500) (Betz, official communication, 2010).

Wildlife Viewing

A variety of information regarding the scales of wildlife tourism in various Gulf Coast areas is 

presented in Lowe and Stokes (2013). For example, this report finds that over 1,100 wildlife guide 
Description of the Affected Environment and Impact Analysis 4-385

businesses support over 11,000 dining and lodging businesses. This report estimated that wildlife 

tourism along the Gulf Coast supports over $19 billion in spending and generates over $5 billion in 

Federal, State, and local tax revenues. The three primary forms of wildlife tourism are fishing (which 

supports $8 billion in spending), wildlife watching (which supports $6.5 billion in spending), and 

hunting (which supports $5 billion in spending). Wildlife tourism supports the most spending in 

Florida ($8 billion) and Texas ($5 billion); wildlife tourism supports approximately $2 billion in 

spending each in Louisiana, Mississippi, and Alabama.

Artificial Reefs

Activities such as recreational fishing and diving are supported by various artificial reef

structures in the Gulf of Mexico. Oil and gas platforms are particularly supportive of recreational 

fishing and diving activities; more information regarding the affected environment for recreational 

fishing is presented in Chapter 4.11 (Recreational Fishing). The locations of oil and gas platforms in 

the GOM can be accessed on the, Energy Information Administration’s online tool that lists all 

energy infrastructure in the GOM (USDOE, Energy Information Administration, 2015e). The Gulf 

Coast States also have programs to develop artificial reef structures (including decommissioned oil 

and gas structures) to support biological diversity and recreational activities. Details regarding these 

programs, including the locations of reef sites, are described in Fikes (2013). Additional information 

regarding BSEE’s Rigs-to Reefs program can be found on BSEE’s website (USDOI, BSEE, 2015f) 

and in Appendix A. 

Marine Protected Areas

The GOM is home to many marine protected areas that support recreational activities such 

as wildlife viewing, nature experiences, and beach visitation. The marine protected areas in the 

GOM include various Federal and State entities, such as parks, wildlife refuges, national marine 

sanctuaries, and national seashores. A map of all of the marine protected areas in the Gulf of 

Mexico can be found on NOAA’s website (USDOC, NOAA, 2015l). Estimates of the number of 

visitors, amount of spending, number of jobs, and amount of income in 2014 supported by each 

national park along the Gulf Coast are provided in Cullinane-Thomas et al. (2015). The number of 

visitors and the amount of visitor spending supported by parks along the Gulf Coast are listed below.

• Padre Island National Seashore (Texas) (578,814 visitors; $23,892,700)

• Jean Lafitte National Historical Park and Preserve (Louisiana) (445,524 visitors; 

$24,986,300)

• Gulf Islands National Seashore (Mississippi and Florida) (4,455,240 visitors; 

$185,611,000) (About 25 percent of these impacts occur in the Mississippi 

District.)

• De Soto National Memorial (Florida) (342,039 visitors; $19,182,600)

• Big Cypress National Preserve (Florida) (1,192,856 visitors; $91,111,200)
4-386 Gulf of Mexico Multisale EIS

• Everglades National Park (Florida) (1,110,900 visitors; $104,476,500)

• Dry Tortugas National Park (Florida) (64,865 visitors; $3,783,600) 

National seashores are expanses of sea coast maintained for the study of wildlife and for 

public recreational use. Additional details regarding the two national seashores in the Gulf of Mexico 

are presented below.

Gulf Islands National Seashore

The Gulf Islands National Seashore consists of two mainland portions and four barrier island 

portions in the northwest Florida panhandle, and a mainland section and six barrier islands in 

Mississippi (Figure 4-26). The Gulf Islands National Seashore was established by Congress in 

1971 to preserve the outstanding natural and recreational values of these areas. In particular, these 

areas are used for diverse recreational activities such as swimming, camping, wildlife-watching, and 

wilderness experiencing. In 1978, Horn and Petit Bois Island were designated as having wilderness 

status. This status reflects the pristine and undeveloped nature of these islands. The Final General 

Management Plan of the Gulf Islands National Seashore provides detailed information regarding the 

recreational opportunities in various locations (USDOI, NPS, 2014a).

Padre Island National Seashore

The Padre Island National Seashore consists of a portion of Padre Island along the southern 

Gulf Coast of Texas. The Padre Island National Seashore was established in 1962 to protect the 

largest stretch of undeveloped barrier island in the world. The Padre Island National Seashore 

offers excellent opportunities for beach visitation, swimming, fishing, birdwatching, and windsurfing. 

More information regarding the recreational opportunities at the Padre Island National Seashore is 

provided in Beach Vehicle Environmental Assessment for Padre Island (USDOI, NPS, 2011b).
Description of the Affected Environment and Impact Analysis 4-387

Figure 4-26. Gulf Islands National Seashore.

4.12.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

recreational resources that would arise from projected activities from a proposed action are analyzed 

in this chapter. While there are some differences in the amount of activities associated with the 

alternatives, many of the impacts associated with the alternatives are similar. Therefore, this 

chapter describes the impacts that are expected to apply to all alternatives, while any deviations 

from these impact conclusions are discussed in Chapters 4.12.2.5-4.12.2.9. 

4.12.2.1 Routine Activities

The following routine OCS oil-and gas-related activities associated with a proposed action 

would potentially affect recreational resources: vessel traffic (Chapter 3.1.4.3); platforms serving as 

artificial reefs (Chapter 3.1.6.2); visibility of OCS platforms (Chapter 3.1.3.4.3); and economic 

factors. 

The OCS vessel traffic can affect the aesthetics of recreational experiences in certain areas. 

The OCS vessel traffic can also cause space-use conflicts with recreational vessels. However, OCS 

vessels move between onshore support bases (which are typically not near recreational areas) and 
4-388 Gulf of Mexico Multisale EIS

production areas far offshore, meaning any potential impact would likely be temporary. In addition, a 

proposed action would add only a small amount of vessel traffic. Chapter 3.1.4.3 provides more 

information regarding OCS vessel traffic. Therefore, impacts from vessel activity would likely be 

negligible to minor.

The OCS platforms serve as artificial reefs and, thus, often have beneficial impacts on 

recreational fishing and diving (Hiett and Milon, 2002). The extent to which a particular platform 

supports recreational activities would depend on numerous factors, such as its distance from shore, 

the fish populations it supports, and the aesthetics of an area (Ditton et al., 2002). The positive 

effects of platforms would be reversed at decommissioning unless a platform is maintained as an 

artificial reef through a Rigs-to-Reefs program (Appendix A). Additional details regarding 

Rigs-to-Reefs and other artificial reef programs, including the locations of reef sites, can be found in 

Fikes (2013). Overall, there would be beneficial (low) to minor adverse impacts on recreational 

resources due to structure installations and removals.

The visibility of OCS platforms can affect the aesthetics of certain recreational areas. These 

impacts depend on the type of recreational area and on the extent to which platforms are visible. 

For example, OCS platforms could detract from the nature experiences in certain Gulf Coast parks. 

The size and location of an offshore structure depends on the reservoir being tapped, characteristics 

of the well-stream fluid, and the type of processing needed to treat the hydrocarbons. The extent to 

which a platform is visible depends on various factors, such its distance, elevation, size, weather 

conditions, air pollution, and lighting (Bounds, 2012). Federal OCS waters are 9 nmi (10.36 mi; 

16.67 km) from the Texas shore, and only under good weather conditions would a platform be visible 

to a person standing at the shoreline or to a person in a multi-story building. Federal OCS waters 

are 3 nmi (3.5 mi; 5.6 km) from Louisiana, Mississippi, and Alabama. In a study conducted by the 

Geological Survey of Alabama (1998), several facets of the visibility of offshore structures were 

analyzed. This study found that visibility is dictated not only by the sizes and locations of the 

structures but also by the curvature of the Earth, atmospheric conditions, and the viewer’s 

expectations and perceptions.

During scoping for recent EISs, NPS raised questions regarding the potential visual impacts 

from OCS platforms to Horn and Petit Bois Islands. Horn and Petit Bois Islands are federally 

designated wilderness areas and are sensitive to disruptions to nature experiences. Cole (2012) is a 

literature review of various types of wilderness experiences. For example, NPS is concerned 

regarding the impacts from OCS platforms on the sky-viewing experiences on these islands, 

particularly at night. The NPS provided BOEM with baseline data regarding the overall scales of 

natural and anthropogenic light at Horn and Petit Bois Islands (USDOI, NPS, 2014a). This data 

found that the anthropogenic light ratio is 537 percent higher than baseline conditions at Horn Island 

and 510 percent higher than baseline conditions at Petit Bois Island. However, these data do not 

distinguish between OCS oil and gas and non-OCS light sources. The U.S. Dept. of Homeland 

Security, Coast Guard (2008) provides more information regarding the lighting requirements for OCS 

structures, such as the number and orientation of lights, to ensure maritime safety.
Description of the Affected Environment and Impact Analysis 4-389

Historical experiences offer some insights into the potential visual impacts of platforms near 

Horn and Petit Bois Islands. Bounds (2012) offers evidence that oil and gas development near 

Dauphin Island (Alabama) caused negative impacts to tourism. The visibility of oil and gas 

structures near Texas and Louisiana appear to have more limited (and in some cases positive) 

impacts (USDOI, NPS, 2001; Nassaur and Benner, 1984), although the visual impacts of platforms 

arising from a proposed action would be subjective depending on the location and people in 

question. For example, platform lighting can detract from some nature experiences but it can also 

improve visibility and add contrast to the landscape. However, the most relevant historical analogy 

is that of offshore development near Mississippi. Figure 4-26 presents information regarding the 

current and historical locations of structures in the vicinity of Horn and Petit Bois Islands. The OCS 

structures have existed close to Petit Bois Island. Most of these have been removed; only a few 

structures remain within 15 mi (11-16 km) of Horn and Petit Bois Islands. No studies have analyzed 

the impacts of the historical OCS structures on visitor experiences. Figure 4-27 is a photograph of 

the remaining OCS structures taken from Petit Bois Island. Figure 4-27 also shows a ship passing 

through the major shipping fairway near Petit Bois Island; the location of this shipping fairway is 

shown in Figure 2-7. This shipping fairway would continue to be used regardless of a proposed 

action. In Figure 4-27, the platforms are barely visible and have less of an impact on the viewshed 

than the passing ship.

Figure 4-27. Photograph of Remaining OCS Structures taken from Petit Bois Island Looking 

South (modified and reprinted with permission from Bob Marsh, [official 

communication, 2016]). (Petit Bois Island is within the Gulf Islands National 

Seashore and is a National Park Service-designated wilderness area.)

An analysis of the visual impacts of a proposed action depends importantly on the locations 

of the structures likely to arise. BOEM provides data on the estimated remaining oil and gas 
4-390 Gulf of Mexico Multisale EIS

reserves for each lease block (USDOI, BOEM, 2016e). This source does not show any known 

remaining oil or gas reserves in nonleased blocks within 10 mi (16 km) of the GUIS. This makes it 

unlikely that a production platform would arise near Horn and Petit Bois Islands in the foreseeable 

future, particularly given the low current energy prices. Even if there were a lease near Horn or Petit 

Bois Island, it would probably be developed using minimal structures that tie back to existing 

platforms due to cost considerations. In addition, BOEM developed the Information to Lessees and 

Operators (ITL) that provides for NPS consultation on a lessee’s plans (excerpt from past ITL 

below), as appropriate, and began adding the ITL to the Notices of Sale for proposed CPA lease 

sales beginning with CPA Lease Sale 231. The lease blocks that have previously been included the 

Gulf Islands National Seashore ITL are illustrated in Figure 2-6. BOEM would expect this ITL to be 

applied to any future GOM lease sales encompassing all or a portion of the CPA. For these 

reasons, potential impacts to these islands would likely be negligible to minor. The overall visual 

impacts of a proposed action would also be negligible to minor because of the distances that OCS 

structures will be from other recreational resources. 

(q) Gulf Islands National Seashore. Potential bidders are hereby notified that 

postlease plans submitted by lessees of whole and partial lease blocks located within 

the first 12 miles of Federal waters near the Gulf Islands National Seashore (State of 

Mississippi Barrier Island Chain Map, enclosed with ITL) may be subject to additional 

review in order to minimize visual impacts from development operations on these 

blocks. BOEM will review and make decisions on a lessee’s plans for these blocks in 

accordance with applicable Federal law and regulations, and BOEM policies, to 

determine if visual impacts are expected to cause serious harm and if any additional 

mitigative action is required. Mitigations may include, but are not limited to, 

requested changes in location, modifications to design or direction of proposed 

structures, pursuing joint use of existing structures on neighboring blocks, changes in 

color design, or other plan modifications. BOEM may consult with the State of 

Mississippi and/or the State of Alabama and with the National Park Service, 

Southeast Regional Office, during such reviews as appropriate.

The following whole and partial blocks, are specifically identified for this ITL: 

Chandeleur Area – 1; Mobile – 765-767, 778, 779, 809-823, 853-867, 897-910, 

942-954, 987-997; and Viosca Knoll – 24-27.

The OCS oil- and gas-related activities can also affect recreational resources indirectly due 

to economic factors (which are described in Chapter 4.14.2.2). First, increased coastal 

infrastructure necessary to support offshore activities can create space-use conflicts. However, 

even if a space-use conflict was to arise in a particular instance, it is likely that a number of 

substitute recreational sites would be available. The OCS oil- and gas-related activities also have 

the potential to increase or decrease the demand for recreational resources in certain communities. 

Increased demand for recreational resources has the potential to attract new recreational firms to a 

community; however, increased demand also has the potential to lessen the enjoyment of a 

particular resource by some community members. The OCS structures could also affect property 
Description of the Affected Environment and Impact Analysis 4-391

values in nearby areas. However, as discussed in Chapter 3.1.7, the existing oil and gas 

infrastructure would likely be sufficient to handle the amount of activity associated with a proposed 

action. Thus, there would likely be no noticeable increase in such impacts. In addition, there is 

sufficient land in the analysis area to handle any new development. Therefore, these indirect 

economic impacts would likely be beneficial (low) to minor. 

4.12.2.2 Accidental Events

Accidental events, such as oil spills and the subsequent response activity and marine trash

and debris, could affect various recreational resources. The impacts of drilling fluid spills and 

chemical spills on recreational resources are expected to be negligible because of their small sizes 

and far distances from recreational resources and are thus not discussed in detail. An oil spill that 

remained offshore could cause closures that may affect recreational fishing, diving, and boating. An 

offshore oil spill could also impact nearby coastal areas through media coverage or through 

misperceptions and uncertainty regarding the extent of the spill. An oil spill would have more direct 

impacts if it were to reach coastal areas. Environmental Sensitivity Indexes (ESIs) provide overall 

measures of the sensitivity of a particular coastline to a potential oil spill. The ESIs rank coastlines 

from 1 (least sensitive) to 10 (most sensitive). Marshes and swamps are examples of resources that 

have ESIs of 10 due to the difficulty of removing oil from these areas. The ESIs for beach areas 

generally range from 3 to 6, depending on the type of sand and the extent to which gravel is mixed 

into the beach area. The ESI maps for any coastline along the Gulf of Mexico can be viewed using 

the National Oceanic and Atmospheric Administration’s ERMA mapping system (USDOC, NOAA, 

2015m). The ESI maps also provide point indicators for recreational resources.

The effects of an oil spill on a region would depend on the size of the spill, as well as the 

success of the containment and cleanup operations following an oil spill. Both manual and machinebased techniques can be used to clean oil; the cleaning technique chosen for a particular beach 

would depend on the nature of the oiling of a particular beach area. The nature of cleanup 

operations would also depend on whether a particular beach serves as a habitat to particular animal 

species because removing oil deep below a beach surface can sometimes do more ecological harm 

than good. As a result, ecological beaches are often only cleaned to a shallow depth, while 

nonecological (“amenity”) beaches are often cleaned more extensively. The cleanup plan for any 

particular beach is determined by a Shoreline Treatment Recommendation, which is prepared by the 

relevant State and Federal agencies for a particular spill. An example of a Shoreline Treatment 

Recommendation following the Deepwater Horizon explosion and oil spill for Grande Isle, Louisiana, 

can be found at RestoreTheGulf.gov (2010).

Recreational resources such as beaches serve as important bases for certain local 

economies. Therefore, oiled beach regions can cause economic losses to both individuals and firms 

in the area of an oiled or closed beach. An economic analysis of the costs of hypothetical beach 

closures along the Texas Gulf Coast was performed by Parsons and Kang (2007). They estimate 

that the economic costs of beach closures along the Padre Island National Seashore would range 

from $26,000 to $172,000 per day, depending on the time of year at which the closures would occur. 
4-392 Gulf of Mexico Multisale EIS

The New Orleans oil spill of 2008 demonstrates that a spill can affect different types of recreational 

activities. Namely, this spill impacted some of the boating and restaurant businesses in its vicinity; it 

also caused some aesthetic impacts to the experiences of tourists in the region (Tuler et al., 2010).

Eastern Research Group (2014b) analyzed the impacts of the Deepwater Horizon oil spill on 

tourism activities in the Gulf region. Eastern Research Group analyzed Deepwater Horizon claims 

data, reviewed newspaper accounts of the spill, analyzed county-level employment data, and 

conducted interviews with people involved in the tourism industry. These various methodologies 

paint a rich picture of the impacts of the Deepwater Horizon explosion, oil spill, and response, and 

revealed some broad conclusions. First, the Deepwater Horizon explosion, oil spill, and response 

had a broad geographic reach, partially due to public perceptions of the nature and scope of the 

spill. In addition, restaurants and hotels were particularly impacted by the Deepwater Horizon

explosion, oil spill, and response, which led areas with more diversified tourism economies to hold 

up better in the spill’s aftermath. Also, tourism generally rebounded strongly after the initial decline. 

Indeed, employment held up well in most counties and parishes following the Deepwater Horizon

explosion, oil spill, and response, which supported the recovery. Finally, the impacts of the spill on 

tourism were shaped by the damage payment system, cleanup processes, and lessons learned from 

prior disasters. The Trustees estimated that the Deepwater Horizon oil spill led to 16.9 million lost 

user days of boating, fishing, and beach-going experiences (Deepwater Horizon Natural Resource 

Damage Assessment Trustees, 2016). However, an oil spill along the lines of the Deepwater 

Horizon oil spill is not reasonably foreseeable and is not considered as part of a proposed action. 

The impacts of a catastrophic oil spill are analyzed in the Catastrophic Spill Events Analysis white 

paper (USDOI, BOEM, 2017).

Any oil spills arising from a proposed action are likely to be small and localized, and thus, the 

corresponding impacts would be less than those experienced after the Deepwater Horizon

explosion, oil spill, and response. In addition, there would likely be response and mitigation efforts 

subsequent to an oil spill. Finally, there would likely be numerous alternative recreational sites 

during the duration of an oil spill of the same type and size of those potentially impacted by 

accidental spills resulting from a proposed lease sale. Therefore, the impacts of an oil spill on 

recreational resources are expected to be negligible to minor. 

Accidental discharges of marine debris from OCS oil- and gas-related vessels and facilities 

could reach beaches and other coastal resources, which could affect the aesthetics of these areas. 

The discharge of marine debris is subject to a number of laws and treaties. These include the 

Marine Debris Research, Prevention, and Reduction Act; the Marine Plastic Pollution Research and 

Control Act; and the MARPOL-Annex V Treaty. Regulation and enforcement of these laws is 

conducted by a number of agencies such as the U.S. Environmental Protection Agency, NOAA, and 

the U.S. Coast Guard. The BSEE provides information on marine debris and awareness and 

requires training of all OCS personnel through the “Marine Trash and Debris Awareness and 

Elimination” NTL (NTL 2015-BSEE-G03). This NTL instructs OCS operators to post informational 

placards on production facilities and drilling rigs that outline the legal consequences and potential 

ecological harms of discharging marine debris. This NTL also states that OCS workers should
Description of the Affected Environment and Impact Analysis 4-393

complete annual marine debris prevention training; operators are also instructed to develop a 

certification process for the completion of this training by their workers. Compliance with this NTL 

would become mandatory if the Protected Species Stipulation were applied. These various laws, 

regulations, and NTL would likely lead the potential damage to recreational resources from the 

discharge of marine debris from OCS operations to be negligible to minor.

4.12.2.3 Cumulative Impacts

The cumulative analysis considers the incremental impacts of a proposed action relative to 

past, present, and future OCS lease sales. The following cumulative OCS oil-and gas-related 

activities would potentially affect recreational resources: marine trash and debris, visibility of OCS 

platforms, space use conflicts, OCS related spills, and infrastructure emplacement and removal. 

This analysis also considers the incremental impacts of a proposed action relative to non-OCS oiland gas-related sources such as aesthetic impacts, beach/wetland erosion, beach disruptions, 

space-use conflicts, and economic factors. 

OCS Oil- and Gas-Related Impacts

Aesthetic Impacts

A proposed action would contribute to aesthetic impacts of the existing and future OCS 

Programs. For example, OCS oil- and gas-related activities contribute to the marine debris 

problems along the Gulf Coast. The BSEE provides information on marine debris and awareness 

and requires training of all OCS personnel through the “Marine Trash and Debris Awareness and 

Elimination” NTL (NTL 2015-BSEE-G03); this NTL is discussed above. Compliance with this NTL, 

particularly if the Protected Species Stipulation is applied, and other regulations as outlined in the 

“Routine Activities” section above would likely reduce the potential damage to recreational resources

from the discharge of marine debris from OCS oil- and gas-related activities.

A proposed lease sale would also add to the visual impacts from the OCS Oil and Gas 

Program. These impacts would depend on the type of recreational area and on the extent to which 

platforms are visible. For example, OCS platforms could detract from the nature experiences in 

certain Gulf Coast parks. As discussed above, during scoping for recent EISs, the National Park 

Service raised questions regarding the potential visual impacts from OCS platforms to Horn and 

Petit Bois Islands. Figure 4-26 presents information regarding the current and historical locations of 

structures in the vicinity of Horn and Petit Bois Islands. The OCS structures have existed close to 

Petit Bois Island for approximately 30 years. Most of these have been removed; a few structures 

remain 7-10 mi (11-16 km) away. Figure 4-27 is a photograph of the remaining OCS structures 

taken from Petit Bois Island, in which these structures are minimally visible. The impacts of any new 

structure would likely be limited unless it was closer to Petit Bois Island than the existing structures. 

However, as discussed previously, it is highly unlikely that such a structure would arise from a 

proposed action because of the locations of oil and gas reserves, economic considerations, and the 

Bureau of Ocean Energy Management’s ITL regarding this issue.
4-394 Gulf of Mexico Multisale EIS

Space-Use Conflicts

A proposed action would also contribute to space-use conflicts between recreational 

activities and the broader OCS Program. Bernhardt et al. (2006) present an analysis of space-use 

conflicts for oil and gas activities off the coast of Texas, although the issues they raise are generally 

applicable to OCS oil- and gas-related activities. They use a GIS-based framework to identify 

specific locations where conflicts between oil activities and other concerns (including recreational 

use) are most acute; they find that recreational use conflicts tend to be concentrated around some of 

the major wildlife viewing and beach areas near the larger population areas in Texas. There would 

also be the potential for space-use conflicts, e.g., near ports, along coastal Louisiana due to the high 

concentration of the OCS oil and gas industry in this area. The vessel traffic near these facilities 

could cause space-use conflicts with boating and recreational fishing activities. However, even if a 

space-use conflict was to arise in a particular instance, it is likely that a number of substitute 

recreational sites would be available. In addition, given the entrenched nature of the OCS oil and 

gas industry along the WPA and CPA, it is unlikely that any particular OCS oil- and gas-related 

activity would significantly add to space-use conflicts. As any of the alternatives would propose 

leasing only a very small portion of the EPA, such space-use conflicts are even less likely in the 

EPA.

Oil Spills

A proposed action would contribute incrementally to the likelihood of an oil spill caused by 

the broader OCS oil- and gas-related activities. Accidental spills most likely would be small, of short 

duration, and not likely to impact Gulf Coast recreational resources. In particular, as shown in Table 

3-17, most spills would range from 0 to 500 bbl. Should an oil spill occur and contact a beach area 

or other recreational resource, it would cause some disruption during the impact and cleanup phases 

of the spill. However, any oil spill arising from a proposed action is expected to be small.

Infrastructure Emplacement and Removal

The overall OCS Oil and Gas Program can contribute to coastal erosion through activities 

such as channel dredging and pipeline emplacements. A more detailed discussion of the cumulative 

impacts of OCS oil- and gas-related activities on coastal beaches and dunes is presented in 

Chapter 4.3.2. Further information on the cumulative impacts of OCS oil- and gas-related activities 

on estuarine ecosystems can be found in Chapter 4.3.1. Platform emplacements can encourage 

some recreational activities, such as fishing and diving. However, decommissioning of these 

structures can have negative impacts on recreational diving if a particular platform were a popular 

diving site. Hiett and Milon (2002) provide survey data that suggest that the majority of recreational 

diving in the Gulf of Mexico occurs near oil and gas structures. More information regarding the 

impacts of infrastructure emplacement and removal is presented above and can be found in 

Chapter 4.11. 

The impacts from aesthetics changes, space-use conflicts, oil spills, and infrastructure

emplacement and removals from the overall OCS Program would be beneficial (medium) to 
Description of the Affected Environment and Impact Analysis 4-395

moderate. This is because of the broader scale of the overall OCS Program compared with a single 

proposed lease sale. The exact impacts would depend on the nature of the oil- and gas-related 

activities and recreational activities in a given area.

Non-OCS Oil- and Gas-Related Impacts

Aesthetic Impacts

Marine debris can detract from the aesthetic values of coastal areas, particularly beaches. 

Non-OCS oil- and gas-related marine debris can originate from State oil and gas activities, sewage 

treatment plants, recreational and commercial fishing, industrial manufacturing, cruise ships, and 

various forms of vessel traffic. Various government agencies participate in a coordinated effort to 

combat marine debris; a broad summary of the issues involved and the policy structure with respect 

to marine debris can be found in the Interagency Marine Debris Coordinating Committee’s report 

(USDOC, NOAA, 2008b). Ocean Conservancy (2007) describes the structure of the National Marine 

Debris Monitoring Program; Ocean Conservancy (2014) is the most recent marine debris monitoring 

report. The incremental impacts of a proposed action are expected to be negligible to minor

because the amount of marine debris that would arise from OCS oil- and gas-related activities would 

be small relative to the amount of marine debris arising from the sources mentioned above.

Aesthetic impacts can also arise from State oil and gas activities. For example, State oil and 

gas activities occur closer to shore and, thus, would cause more noise and visual impacts than OCS 

oil- and gas-related activities. In 2014, Mississippi’s plans to hold an offshore oil and gas lease sale 

in State waters were suspended when a judge ruled against Mississippi’s determination that such 

leases were purely administrative actions (NOLA.com, 2014). It is unclear how this issue would 

evolve. The visual impacts to Horn and Petit Bois Islands would also be influenced by the major 

shipping fairway between the islands. This shipping artery (which is shown in Figure 4-26) leads to 

the Port of Pascagoula, which is the 21st most active port in the United States (U.S. Dept. of the 

Army, COE, 2015c). A proposed action should also be viewed in light of the overall levels of noise 

on Horn and Petit Bois Islands. White (2014) provides data on baseline noise levels at Horn and 

Petit Bois Islands relative to Fort Pickens (which is a nonwilderness, higher human use area) in the 

Florida District of the Gulf Islands National Seashore. This study found that Horn and Petit Bois 

Islands have lower overall levels of extrinsic noise than Fort Pickens. Horn and Petit Bois Islands 

have higher measures of watercraft noise and lower levels of aircraft noise than Fort Pickens.

Beach/Wetland Erosion

The OCS Program occurs in an environment in which beach and wetland resources are 

undergoing depletion due to human development, hurricanes, and natural processes. The ongoing 

risk of hurricanes is a particular coastal erosion threat in the Gulf of Mexico; coastal erosion also 

lessens protection against future hurricanes. Non-OCS-related oil spills also have the potential to 

contribute to beach erosion, both due to contaminated sediment and the potential sediment losses 

during the cleanup process. More information regarding these issues can be found in Chapter 

3.3.2.8. Coastal erosion trends would have impacts on recreational resources to the extent that 
4-396 Gulf of Mexico Multisale EIS

parts of these areas are used for recreational activities, such as beach visitation, recreational fishing, 

and boating.

Beach Disruptions

The recreational value of beaches can be affected by beach disruptions. For example, red 

tides, which are caused by growth of microscopic algae, can negatively impact the aesthetic value of 

beaches. Red tides can also cause respiratory problems and skin irritation for beachgoers (State of 

Texas, Dept. of State Health Services, 2015). As discussed in Chapter 4.3.2 (Coastal Barrier 

Beaches and Associated Dunes), beaches can also be affected by changes in water and sediment 

flow. The recreational value of beaches can also be negatively impacted by degradations of air 

quality and water quality (Chapters 4.1 and 4.2).

Space-Use Conflicts

Space-use conflicts with recreational activities may arise from commercial and military traffic. 

Chapter 3.3.2.6.1 describes the military activities in the vicinity of a proposed action. For example, 

Chapter 3.3.2.6.1 discusses the military warning areas and Eglin water test areas, as well as the 

Military Areas Stipulation that applies to GOM leases. Chapter 4.14.1.2 describes the cumulative 

impacts of vessel traffic, including the ports that support the highest vessel traffic. These activities 

could disrupt recreational fishing, diving, and boating.

Economic Factors

The recreational resources along the Gulf Coast would be subject to various impacts arising 

from economic development. For example, there may be pressures to develop other industries into 

existing parks and natural resources. However, development may also encourage the expansion of 

other recreational resources, such as hotels and restaurants, to accommodate increased tourism

and/or local recreation. The projected path of the economies along the Gulf Coast would be 

influenced by national economic trends. Recreational and tourism activity is positively correlated to 

the state of the overall national economy because higher levels of disposable income encourage 

consumers to dedicate more money to travel and leisure activities. More information regarding 

economic factors can be found in Chapter 4.14.2. 

Overall non-OCS oil- and gas-related impacts would range from beneficial (high) to major. 

This wide range reflects the myriad of non-OCS oil- and gas-related impacts that could occur over 

the time-frame of this cumulative analysis. For example, beach and wetland erosion could have 

major impacts to recreational activities in certain areas. In addition, economic developments could 

have important beneficial or adverse impacts to recreational resources. However, the various 

recreational resources in the Gulf of Mexico, as well as economic and social adjustments to impacts, 

should generally support high levels of recreational activities in the future. 
Description of the Affected Environment and Impact Analysis 4-397

Incremental Impacts

A single proposed lease sale would be relatively small when compared with all past, present, 

and future lease sales (refer to Table 3-23). A proposed action would also be relatively small when 

compared with the non-OCS oil- and gas-related factors discussed above (refer to Chapter 3). For 

example, marine debris or visual disruptions would be more likely to arise from non-OCS oil- and 

gas-related activities such as shipping traffic. In addition, a proposed action would have small 

impacts relative to the space-use conflicts, beach/wetlands erosion, and economic factors that will 

impact recreational resources. Therefore, the incremental cumulative impacts of a proposed action 

relative to these OCS- and non-OCS oil- and gas-related factors would range from beneficial (low)

to minor. 

4.12.2.4 Incomplete or Unavailable Information

There is some incomplete or unavailable information regarding the visual impacts from a 

proposed action. In particular, the attitudes of people towards the visibility of structures that could 

arise in certain areas are not fully known. BOEM has determined that such information is not 

essential to a reasoned choice among alternatives because much of this uncertainty relates to the 

inherent uncertainty regarding where (and what types) of structures would arise from a proposed 

action. In addition, existing information allows for sufficient estimates of the overall dependence of 

visual impacts to factors such as distance, height, brightness, and general location. BOEM used 

generally accepted scientific principles to estimate the visual impacts of a proposed action, including 

literature sources, data sources, and photographic evidence. This evidence suggests that the 

incremental visual impacts of a proposed action would be negligible to minor. In addition, BOEM 

has issued an ITL to ensure that visual impacts near the Gulf Islands National Seashore are 

considered at BOEM’s site-specific review stage.

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

The impacts of a proposed action would correspond to the impacts described in Chapter 

4.12.2. In particular, a proposed action would contribute to the negative aesthetic impacts and the 

space-use conflicts that arise due to the broader OCS Oil and Gas Program. Structure 

emplacements can have positive impacts on recreational fishing and diving because platforms often 

act as artificial reefs, although decommissioning would offset these impacts. Oil spills can negatively 

impact beaches and other coastal recreational resources. The impacts resulting from the routine 

activities and accidental events would range from beneficial (low) to minor. A proposed action 

should also be viewed in light of economic trends, as well as various non-OCS oil- and gas-related 

factors than can cause space-use conflicts and aesthetic impacts, such as commercial and military 

activities. The incremental cumulative impacts of Alternative A relative to the impacts of all other 

OCS oil- and gas-related and non-OCS oil- and gas-related factors would be beneficial (low) to 

minor. 
4-398 Gulf of Mexico Multisale EIS

4.12.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative B. There would be some 

differences in impacts between Alternatives A and B due to the scales of OCS oil- and gas-related 

activities (described in Chapter 4.12.1) and to the geographic distributions of activities. Namely, 

Alternative B would prevent most impacts to recreational resources near drilling and production 

activities in Federal waters off Texas. However, since CPA/EPA activities may still be serviced by 

vessels departing from Texas ports, there could still be some space-use conflicts or impacts from oil 

spills near Texas. However, the differences between Alternatives A and B are not large enough to 

change the broad impact measures. In particular, Alternative B would contribute to the negative 

aesthetic impacts and the space-use conflicts that arise due to the broader OCS Oil and Gas 

Program. Structure emplacements can have positive impacts on recreational fishing and diving 

because platforms often act as artificial reefs, although decommissioning would offset these impacts. 

Oil spills can negatively impact beaches and other coastal recreational resources. Alternative B 

should also be viewed in light of economic trends, as well as various non-OCS oil- and gas-related 

factors than can cause space-use conflicts and aesthetic impacts such as commercial and military 

activities. The incremental cumulative impacts of Alternative B relative to the impacts of all other 

OCS oil- and gas-related and non-OCS oil- and gas-related factors would be beneficial (low) to 

minor. 

4.12.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available Unleased 

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

Alternative C entails leasing a subset of the area considered in Alternative A. Therefore, the 

analysis of Alternative A covers the potential impacts of Alternative C. There would be some 

differences in impacts between Alternatives A and C due to the scales of OCS oil- and gas-related 

activities (described in Chapter 4.12.1) and to the geographic distributions of activities. Namely, 

Alternative C would prevent most impacts to recreational resources near drilling and production 

activities in CPA/EPA Federal waters. However, since activities in the WPA may still be serviced by 

vessels departing from ports adjacent to the CPA/EPA, there could still be some space-use conflicts 

or impacts from oil spills near all Gulf Coast States. However, the differences between Alternatives 

A and C are not large enough to change most of the broad impact measures. The only difference is 

that the visual impacts due to structure emplacements should be negligible because all structures 

would be at least 9 nmi (10.36 mi; 16.67 km) from shore and because there would be fewer structure 

installations in the WPA than in the CPA. In addition, Alternative C would prevent visual impacts to 

the GUIS from structure installations. Alternative C would contribute to the negative aesthetic 

impacts and the space-use conflicts that arise due to the broader OCS Program. Structure 

emplacements can have positive impacts on recreational fishing and diving because platforms often 

act as artificial reefs, although decommissioning would offset these impacts. Oil spills can negatively 

impact beaches and other coastal recreational resources. Alternative C should also be viewed in 

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

space-use conflicts and aesthetic impacts such as commercial and military activities. The 
Description of the Affected Environment and Impact Analysis 4-399

The magnitude of impact to an 

archaeological site expresses the maximum 

severity of potential impacts, should they 

occur, in spite of or in the absence of an 

assigned mitigation. BOEM does not 

differentiate between archaeological site 

types when conducting an impact analysis at 

the programmatic level.

incremental cumulative impacts of Alternative C relative to the impacts of all other OCS oil- and gasrelated and non-OCS oil- and gas-related factors would be beneficial (low) to minor. 

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

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

Blocks South of Baldwin County, Alabama, Stipulations

Alternative D entails leasing a subset of the area considered in Alternative A, B, or C. 

Therefore, the analysis of Alternative A, B, or C covers the potential impacts of Alternative D. The 

areas that would be restricted from leasing under Alternative D would generally be far from shore 

and comprise a small portion of recreational activities along the Gulf Coast. In addition, there would 

be some offsetting adverse impacts (due to aesthetics, space-use conflicts, and oil spills) and some 

beneficial impacts (due to structure emplacements). The exclusion of blocks south of Baldwin 

County would prevent some potential negative impacts to tourism arising from the visibility of OCS 

oil- and gas-related infrastructure; it would also prevent the space-use conflicts, aesthetic impacts, 

and impacts from accidental events described above. However, the exclusion of these blocks would 

not prevent similar impacts in other GOM areas. Therefore, the overall impact conclusions for 

Alternative D are the same as those concluded under Alternative A, B, or C, as appropriate.

4.12.2.9 Alternative E—No Action

Under Alternative E, the impacts discussed above would not occur as a result of a proposed 

lease sale. There could be negligible impacts to recreational resources due to the small economic 

adjustments that would occur in light of Alternative E. For example, Alternative E would lower the 

income of employees in the offshore oil and gas supply chain, which could slightly lessen the 

demand for recreational activities. However, recreational resources would still be subject to the 

impacts from the broader OCS Oil and Gas Program, as well as the impacts from the non-OCS oiland gas-related sources discussed above. In the short term, there would be a reduction of 

exploration and drilling activities, and there would be fewer impacts from the space-use conflicts, oil 

spills, and aesthetics of such activities. If lease sales were not held for a lengthy period of time, 

there may be a long-term reduction in impacts arising from production activities (such as the role of 

platforms as artificial reefs) as mature leases reach the end of their production period and are 

decommissioned. Tthe Five-Year Program EIS presents more information regarding the impacts of 

a long-term cessasion of leasing activities.

4.13 ARCHAEOLOGICAL RESOURCES

Archaeological resources are any material 

remains of human life or activities that are at least 

50 years of age and that are capable of providing 

scientific or humanistic understanding of past 

human behavior, cultural adaptation, and related 

topics through the application of scientific or 

scholarly techniques, such as controlled 
4-400 Gulf of Mexico Multisale EIS

observation, contextual measurement, controlled collection, analysis, interpretation, and explanation 

(30 CFR § 550.105). The full analyses of the potential impacts of routine activities and accidental 

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

cumulative impacts are presented in the following sections. The approach of the analysis is to focus 

on the potential impact-producing factors from routine OCS oil- and gas-related activities (i.e., 

exploration, development, and production), as well as accidental events and cumulative impacts 

(Table 4-31). A brief summary of potential impacts follows. Archaeological resources are primarily 

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

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

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

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

of existing channels; anchoring activities; post-decommissioning activities including trawling 

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

debris. Visual impacts to coastal archaeological and historic sites are not considered, as offshore oil 

and gas infrastructure has existed on the Gulf of Mexico OCS since the 1940s and constitutes a 

seaward historic viewshed in its own right. Additionally, offshore oil and gas infrastructure predates 

the NHPA, and therefore, any coastal historic property currently on the National Register of Historic 

Places would not derive its eligibility from an unobstructed view of the GOM.

Impact-Level Definitions

The definition of impact thresholds used in this analysis are listed below.

• Negligible – The lowest level of detection that would have neither adverse nor 

beneficial impacts.

• Minor – Disturbance of archaeological resources would result in little, if any, loss 

of site integrity.

• Moderate – Site disturbance would result in a loss of integrity and a partial loss 

of the character-defining features and information potential that form the basis of 

the site’s National Register of Historic Places’ eligibility. Mitigation is 

accomplished by a combination of archeological data recovery and in-place 

preservation.

• Major – The disturbances result in a loss of site integrity to the extent that the 

resource is no longer eligible for listing in the National Register of Historic Places. 

The site’s character-defining features and information potential are lost to the 

extent that archeological data recovery is the primary form of mitigation. 

• Beneficial – An archeological site is stabilized in its current condition to maintain 

its existing level of integrity or an archeological site is preserved in accordance 

with the Secretary of the Interior’s Standards for the Treatment of Historic 

Properties. 
Description of the Affected Environment and Impact Analysis 4-401

Duration: Short-term impacts last for the duration of construction-related activities while 

long-term impacts last beyond the proposed construction activities and are permanent. Generally, 

impacts to archeological sites are considered long-term impacts.

The impact of coastal and marine environmental degradation from OCS oil- and gas-related 

activities is expected to minimally affect cultural resources in comparison to other sources of coastal 

erosion and subsidence. Impacts of routine discharges are localized in time and space, are 

regulated by USEPA permits, and would have minimal impact. Accidental events that could impact 

archaeological resources include blowouts and oil or chemical spills and the associated cleanup 

response activities, and also the loss of debris from an MODU, platform, lay barge, etc. during 

offshore operations. A noncatastrophic oil spill (even one reasonably foreseeable as a result of a 

proposed lease sale) occurring and contacting a submerged archaeological resource is unlikely, 

given that oil released tends to rise quickly to the surface and that the most common size of a spill is 

<1 bbl (refer to Chapter 3.2.1.5.3).

Archaeological surveys, where required prior to an operator beginning OCS oil- and gasrelated activities, are expected to be effective at identifying possible archaeological sites. Offshore 

oil and gas activities resulting from a proposed action could adversely impact an archaeological 

resource because of incomplete knowledge on the location of these sites in the GOM. The risk of 

contact to archaeological resources is greater in instances where archaeological survey data are 

unavailable. Such an event could result in the disturbance or destruction of important archaeological 

information. Archaeological surveys provide the necessary information to develop avoidance 

strategies that would reduce the potential for adverse impacts on archaeological resources. As part 

of the environmental reviews conducted for postlease activities, available information would be 

evaluated regarding the potential presence of archaeological resources within the proposed action 

area to determine if additional archaeological resource surveys and mitigation is warranted.

4.13.1 Description of the Affected Environment

4.13.1.1 Prehistoric

Available evidence suggests that sea level in the northern GOM was at least 90 m (295 ft), 

and possibly as much as 130 m (427 ft), lower than present sea level during the period 

20,000-17,000 years Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern Gulf 

reached its present stand around 3,500 years B.P. (Pearson et al., 1986). During periods that the 

continental shelf was exposed above sea level, the area was open to habitation by prehistoric 

peoples.

Until the late 20th century, it was generally accepted by archaeologists that the earliest 

humans in North America were the so-called Clovis peoples, named for a lanceolate-shaped, fluted 

projectile point first found near Clovis, New Mexico. The Clovis culture was thought to have entered 

the continent by way of Beringia, a landmass connecting Asia to North America exposed during the 

Last Glacial Maximum, and along an ice-free corridor opened between the Cordilleran and 

Laurentide ice sheets around 13,500 years B.P. Today, however, a growing body of evidence has 
4-402 Gulf of Mexico Multisale EIS

dispelled the “Clovis First” model with discovery of several sites with indisputable pre-Clovis dates in 

the eastern United States (Goodyear, 2005), Chile (Dillehay, 1989; Meltzer et al., 1997) and central 

Texas (Waters et al., 2011). The Buttermilk Creek Complex identified by Waters et al. (2011) at the 

Debra L. Friedkin Site (41BL1239) is the nearest to the Gulf of Mexico region and is dated from 

~13,200 to 15,000 years B.P.

Establishing a reliable date for the entrance of Native Americans into the coastal regions of 

the GOM is complicated by the fact that archaeological deposits pre-dating 5500 B.P. lie buried 

under as much as 40 m (131 ft) of sediment or are underwater on the OCS (Rees, 2010). 

Conclusive evidence for prehistoric sites on the OCS is sparse. The McFaddin Beach Site (41JF50) 

in Jefferson County, Texas, has produced hundreds of artifacts 8,000 years old or older that have 

been redeposited from sites eroding from the now-submerged Pleistocene shoreline. Forty-three 

percent of the total sample includes artifacts diagnostic of the Middle and Late Paleoindian periods 

and include Clovis, Dalton, Scottsbluff, and San Patrice projectile points (Stright et al., 1999).

Recent archaeological research in Florida has confirmed that Pre-Clovis peoples inhabited 

the southeastern region of North America more than 14,500 years ago (Halligan et al., 2016). The 

sea-level curve for the northern GOM proposed by Coastal Environments, Inc. (CEI) suggests that 

sea level at 12,000 years B.P. would have been approximately 45-60 m (148-197 ft) below the 

present-day sea level (CEI, 1977 and 1982). On this basis, the continental shelf shoreward of the 

45- to 60-m (148- to 197-ft) bathymetric contours has potential for prehistoric sites dating after 

12,000 years B.P. Because of inherent uncertainties in both the depth of sea level and the entry 

date of prehistoric man into North America, BOEM adopted the 60-m (197-ft) water depth as the 

seaward extent for prehistoric archaeological site potential in GOM region.

Based on their 1977 baseline study, CEI (1977) proposed that sites analogous to the types 

of sites frequented by Paleoindians can be identified on the now-submerged shelf. Geomorphic 

features that have a high potential for associated prehistoric sites include barrier islands and backbarrier embayments, river channels and associated floodplains and terraces, and salt-dome 

features. Investigations in Louisiana and Florida indicate the mound-building activity by prehistoric 

inhabitants may have occurred as early as 6,200 years B.P. (cf. Haag, 1992; Saunders et al., 2005; 

Russo, 1992). Therefore, manmade features, such as mounds, may also exist in the shallow 

inundated portions of the OCS.

Regional geological mapping studies by BOEM allow interpretations of specific geomorphic 

features and assessments of archaeological potential in terms of age, type of system the 

geomorphic features belong to, and geologic processes that formed and modified them. In general, 

sites protected by sediment overburden have a high potential for preservation from the destructive 

effects of marine transgression. The same holds true for sites submerged in areas subjected to low 

wave energy and for sites on relatively steep shelves, which were inundated during periods of rapid 

rise in sea level. Although many specific areas in the GOM having potential for prehistoric site 

preservation have been identified through archaeological surveys, industry generally has chosen to 

avoid these areas rather than conduct further investigations.
Description of the Affected Environment and Impact Analysis 4-403

Holocene sediments form a thin veneer or are absent over the majority of the continental 

shelf off western Louisiana and eastern Texas (USDOI, MMS, 1984). Many large, late Pleistocene, 

fluvial systems (e.g., the Sabine-Calcasieu River Valley) are within a few meters of the seafloor in 

this area. Farther to the south and west, a blanket of Holocene sediments overlies the Pleistocene 

horizon. Along the coast, prehistoric sites representing the Paleoindian culture period through 

European contact have been reported. The McFaddin Beach site, east of Galveston in the 

McFaddin National Wildlife Refuge, has produced late Pleistocene megafauna remains and lithics 

from all archaeological periods, including a large percentage of Paleoindian artifacts (Stright et al., 

1999). A study funded by the Minerals Management Service (MMS) (BOEM’s predecessor) to 

locate prehistoric archaeological sites in association with the buried Sabine-Calcasieu River Valley 

was completed in 1986 (CEI, 1986). Five types of relict landforms were identified and evaluated for 

archaeological potential. Coring of selected features was performed, and sedimentary analyses 

suggested the presence of at least two archaeological sites.

High-resolution geophysical surveys have produced evidence of floodplains, terracing, and 

point-bar deposits in association with relict late Pleistocene fluvial systems. Prehistoric sites 

associated with these features would have a high potential for preservation. Salt diapirs with 

bathymetric expression have also been recorded during lease-block surveys in this area. Solution 

features at the crest of these domes would have a high potential for preservation of associated 

prehistoric sites. The Salt Mine Valley site on Avery Island is a Paleoindian site associated with a 

salt-dome solution feature (CEI, 1977). The proximity of most of these relict landforms to the 

seafloor facilitates further investigation and data recovery.

4.13.1.2 Historic

Historic archaeological resources on the OCS consist of historic shipwrecks and a single 

historic lighthouse, the Ship Shoal Light. A historic shipwreck is defined as a submerged or buried 

vessel or its associated components, at least 50 years old, that has foundered, stranded, or 

wrecked, and that is currently lying on or embedded in the seafloor. Europeans are known to have 

traversed the waters of the western Gulf of Mexico as early as Captain Alonso Alvarez de Piñeda’s 

expedition in 1519. Alvar Nuñez Cabeza de Vaca is likely to have the dubious distinction of being 

the first European to be shipwrecked along the Texas coast as early as 1528 (Francaviglia, 1998).

The NPS and MMS (BOEM’s predecessor) contracted three studies (CEI, 1977; Garrison 

et al., 1989; Pearson et al., 2003) aimed at modeling areas in the GOM where historic shipwrecks 

are most likely to exist, though numerous shipwreck discoveries since the publication of those 

studies have empirically shown their models to be flawed due to reporting biases in the historic 

record. The 1977 study concluded that two-thirds of the total number of shipwrecks in the northern 

GOM lie within 1 mi (1.6 km) of shore and most of the remainder lies between 1 and 6 mi (1.6 and 

10 km) of shore (CEI, 1977). Changes in the late 19th- and early 20th-century sailing routes 

increased the frequency of shipwrecks in the open sea in the eastern GOM to nearly double that of 

the central and western GOM (Garrison et al., 1989). The Garrison et al. study also found the 

highest observed frequency of shipwrecks occurred within areas of intense marine traffic, such as 
4-404 Gulf of Mexico Multisale EIS

the approaches and entrances to seaports and the mouths of navigable rivers and straits. Based on 

the results of this study, MMS identified which OCS lease blocks would require the operator to 

submit an archaeological report with their EP, DOCD, DPP, or other permit application.

Pearson et al. (2003) benefited from the experience of almost 15 years of high-resolution, 

shallow hazard surveys in lease blocks (a typical lease block is 9 mi2 [5,760 ac]) and along pipeline

routes. Some of these surveys (almost exclusively for pipeline routes) were conducted in deep 

water. Taking the new data into account, the 2003 study recommended including some deepwater 

areas, primarily on the approach to the Mississippi River, among those lease areas requiring 

archaeological investigation. With this in mind, MMS (BOEM’s predecessor) revised its guidelines 

for conducting archaeological surveys and added about 1,200 lease blocks in the CPA to the list of 

blocks requiring an archaeological survey and assessment. These requirements are posted on 

BOEM’s website under NTL 2005-G07 and NTL 2011-JOINT-G01. Based on additional shallow 

hazard survey data and shipwreck discoveries since 2008, an archaeological survey may be 

required as a result of site-specific NEPA analysis conducted for new bottom-disturbing activity 

associated with plans (USDOI, BOEMRE, 2011), pipelines, and structure-removal activities. Table

4-30 illustrates the results of the surveys and archaeological reviews in the last 6 years.

Table 4-30. Archaeological Surveys and Resources Identified, 2009-2014.

Year Blocks 

Surveyed

Identified 

Shipwreck Sites

Potential Archaeological Sites Mitigated by Avoidance

(identified through requisite industry surveys)

2009 118 11 479 magnetic anomalies and 103 sonar targets

2010 74 8 274 magnetic anomalies and 100 sonar targets

2011 120 15 577 magnetic anomalies and 171 sonar targets

2012 115 15 341 magnetic anomalies and 112 sonar targets

2013 166 6 374 magnetic anomalies and 163 sonar targets

2014 144 13 417 magnetic anomalies and 146 sonar targets

Many of the above-listed shipwrecks were not previously known to exist in these areas from 

the historic record. Recent research on historic shipping routes, moreover, suggests that the ultradeepwater area of the Gulf of Mexico, between 25o and 27.5o N. latitude, was located along the 

historic Spanish trade route, which therefore increases the probability that a historic shipwreck could 

be located in this area (Lugo-Fernandez et al., 2007). This route runs through the proposed action 

area. A study to conduct archival research on these historic shipping routes was completed in 2010 

(Krivor et al., 2011) and concluded that both Spanish and French vessels were lost in the 16th, 17th, 

and 18th centuries while transiting the route between Vera Cruz, New Orleans, and Havana.

A proprietary database of shipwrecks maintained by BOEM currently lists over 1,300 named 

shipwrecks in the GOM. Many of these reported shipwrecks may be considered historic and could 

be eligible for nomination to the National Register of Historic Places. Most of these wrecks are 

known only through the historical record and, to date, have not been located on the ocean floor. 

This list should not be considered exhaustive; regular reporting of shipwrecks did not occur until late 
Description of the Affected Environment and Impact Analysis 4-405

in the 19th century, and losses of several classes of vessels, such as small coastal fishing boats, 

were largely unreported in official records.

Submerged shipwrecks off the coasts of Texas, Louisiana, Mississippi, and Alabama are 

likely to be moderately well-preserved because of the high sediment load in the water column from 

upland drainage and wind and water erosion. Wrecks occurring within or close to the mouth of bays 

likely would have been quickly buried by transported sediment and therefore somewhat protected 

from the destructive effects of wood-eating shipworms (Teredo navalis) or storms, as has been 

observed at the site of La Belle in Matagorda Bay, Texas (Bruseth and Turner, 2005). Wrecks 

occurring in deeper water also have a moderate to high preservation potential. In the deep water, 

temperature at the seafloor is extremely cold (~4 oC; 39 oF), which slows the oxidation of ferrous 

metals. While the cold water at depth would eliminate the wood-eating shipworm Teredo navalis, it 

is clear from recent studies that other marine organisms, including chemosynthetic species, 

consume wooden shipwrecks, and that microbial organism are at work breaking down steel and iron 

hulls (Atauz et al., 2006; Church et al., 2007; Church and Warren, 2008; Ford et al., 2008). Due to 

the high levels of preservation and the decrease in impacts from anthropogenic (e.g., diving, looting, 

and fishing trawling) and meteorological (e.g., tropical storms and hurricanes) events, the potential is 

higher in deep water to discover undisturbed sites.

Hurricane activity in the Gulf of Mexico has the ability to directly impact archaeological 

resources in water depths exceeding 200 ft (61 m) (Gearhart et al., 2011; Lukens and Selberg, 

2004). Wrecks occurring as a result of an extremely violent storm are more likely to be scattered 

over a broad area. The wreckage of the 19th-century steamer New York, which was destroyed in a 

hurricane, lies in 65 ft (20 m) of water and has been documented by MMS/BOEM (Irion and 

Anuskiewicz, 1999; Gearhart et al., 2011) as scattered over the ocean floor in a swath over 1,500 ft 

(457 m) long. Shipwrecks occurring in shallow water nearer to shore are more likely to have been 

reworked and scattered by subsequent storms than those wrecks occurring at greater depths on the 

OCS.

It is almost certain that any shipwrecks in shallow water within the path of Hurricanes Katrina 

or Rita were impacted to some extent by these storms. In September 2005, the NPS conducted a 

study of sites along the Gulf Coast that were impacted by Hurricane Katrina (USDOI, NPS, 2005). 

This assessment identified three types of damage that can occur to archaeological sites: tree 

throws; storm surge, scouring, and erosion; and seabed shifting. On the OCS, the two primary types 

of damage would be associated with storm surge and seabed shifting. In early 2007, MMS awarded 

a study to investigate the impacts that recent storm activity may have had on historic shipwrecks in 

the Gulf of Mexico. Analysis of the remote-sensing surveys and diver investigations indicates that at 

least 3 of the 10 shipwrecks examined were affected by recent storm activity and that older wooden 

wrecks that had achieved some level of equilibrium in their environment were less affected than 

more recent steel-hulled wrecks (Gearhart et al., 2011).
4-406 Gulf of Mexico Multisale EIS

4.13.2 Environmental Consequences

Impacts to archeological sites occur when proposed activities result in complete or partial 

destruction of the resource and are equivalent to a loss of integrity as defined in the National Historic 

Preservation Act (NHPA) (54 U.S.C. §§ 300101 et seq.). In determining the appropriate impact 

threshold, both the extent to which the proposed activity results in a loss of integrity and the degree 

to which losses can be compensated by mitigating activities, including preservation or data recovery, 

are considered. For the purposes of this analysis, all alternatives may be assumed to have 

effectively similar potential impacts to archaeological resources. Only those resources determined 

eligible or potentially eligible for listing in the National Register of Historic Places are considered 

under the NHPA. Resources are eligible for listing in the National Register of Historic Places if they 

meet one or more eligibility criteria (for archeological sites, generally Criterion D, having the potential 

to provide information important to history or prehistory) and if they possess integrity. For purposes 

of archaeological mitigation, BOEM/BSEE considers all uninspected shipwrecks, sonar targets, and 

magnetic anomalies to be potentially eligible for the National Register of Historic Places.

For the analysis of impacts to archeological resources, the determination of the intensity of 

an impact is based on the foreseeable loss of integrity to known or potential resources. The analysis 

considers only the direct impacts of seafloor disturbance associated with the below-listed impactproducing factors as there should be no additional impacts upon archeological resources under any 

of the alternatives under consideration upon completion of said activities. As each archaeological 

resource is unique and exists at a specific location on the seafloor, there is a high level of variability 

in how a site may be impacted by any potential impact-producing factor. Therefore, it is impossible 

to evaluate the potential impact to an archaeological site from a proposed action at the 

programmatic level. During postlease activities, each permitted action would be assessed for 

site-specific potential impacts during the permit application process, and avoidance buffers would be 

placed around identified resources in order to mitigate potential impacts.

4.13.2.1 Routine Activities

Routine impact-producing factors associated with a proposed action that could affect 

archaeological resources include (1) geotechnical testing/geophysical surveys; (2) well development 

(drilling), structure installation, and maintenance; (3) pipeline installation and maintenance; 

(4) vessel or structure anchoring; and (5) idle structure removal. 

Geotechnical Testing/Geophysical Surveys

Geotechnical testing includes, but is not limited to, soil boring, seafloor coring, and sediment 

grabs. The area of effect for a typical geotechnical test is approximately 1 m2 (11 ft2

); however, 

several tests are usually conducted as part of a project. The likelihood that an individual test would 

negatively impact an archaeological site in an unsurveyed area is minimal; however, the effect to an 

impacted site would be significant were it to occur. Large area geophysical surveys to resolve deep 

geological structures use either ocean bottom cables or ocean bottom nodes as acoustic receivers. 

The ocean bottom cables are deployed from a surface vessel onto the seafloor. While the cable 
Description of the Affected Environment and Impact Analysis 4-407

itself is light and flexible, the acoustic node assembly and sound dampeners can weigh up to 

approximately 400 lb (181 kg). The “blind” method of laying down and peeling up the cable from the 

seafloor could cause the cable to snag on an unknown shipwreck, causing major adverse impacts. 

The ocean bottom nodes are either dropped from a surface vessel, with a large area of potential 

bottom contact, or they are placed by ROVs. An archaeological survey is not required in advance of 

a geophysical survey; however, identified and potential archaeological resources are noted for 

avoidance. The deployment of ocean bottom cables and ocean bottom nodes dropped from the 

surface have the potential to significantly negatively impact unidentified archaeological resources. 

The ocean bottom nodes placed by ROV have minimal potential to impact archaeological resources 

as the seafloor is visually inspected before placement and recovery. Impacts to archaeological 

resources from the geotechnical testing/geophysical survey range from negligible to major if no 

survey is performed, no mitigation is imposed, a mitigation is not followed, or a site is unidentified 

prior to the activity.

Well Development (Drilling), Structure Installation, and Maintenance

In total, approximately 6,700 platforms have been installed in the GOM. For fixed-legged 

structures, depending on water depth, seafloor characteristics, and vessel availability, an anchored 

barge, moored barge, or liftboat may be used in platform installation. Wells are typically drilled in a 

new location prior to structure installation. Depending primarily on water depth and vessel 

availability, a jack-up rig or anchored or dynamically positioned MODU may be used. Several 

directional wells may be drilled from a single top-hole location. Estimates of wells to be drilled and 

platforms to be installed, by water depth, are presented in Table 3-2. Impacts to archaeological 

resources from well development, structure installation, and maintenance activities range from 

negligible to major if no survey is performed, no mitigation is imposed, a mitigation is not followed, 

or a site is unidentified prior to the activity.

Pipeline Installation and Maintenance

Pipelines in the Gulf of Mexico OCS are installed as either a part of lease-block infrastructure

or as a right-of-way across others’ leases or unleased areas. Pipeline permits allow an operator to 

install a pipeline within a planned 200-ft (61-m) corridor. Pipelines are laid with either an anchored 

or a dynamically positioned lay barge. Pipelines installed in water depths <200 ft (61 m) and those 

deemed a hazard to navigation must be buried at least 3-16 ft (1-5 m) depending on local uses (e.g., 

fairways, anchorages, etc.), typically using a water jet. Long segments have been observed to flex 

and move across the seafloor, usually due to storm activity. A survey for all proposed pipeline 

installation, regardless of location, has only been required since 2005. An example of an adverse 

impact to an archaeological site from a pipeline installation is the 2001 installation of an oil and gas 

pipeline that bisected and damaged what is known as the Mica Shipwreck (Atauz et al., 2006). 

Impacts to archaeological resources from pipeline installation and maintenance activities range from 

negligible to major if no survey is performed, no mitigation is imposed, a mitigation is not followed, 

or a site is unidentified prior to the activity.
4-408 Gulf of Mexico Multisale EIS

Vessel or Structure Anchoring

Anchoring associated with exploration drilling, platform and pipeline emplacement, and 

decommissioning may also physically impact archaeological resources. It is assumed that, during 

anchor emplacement, an array of 20,000-lb (9,072-kg) anchors is repositioned within the area of 

potential effect. The anchor’s chain has the potential to lie along and sweep across the seafloor. 

Impacts to archaeological resources from anchoring activities range from negligible to major if no

survey is performed, no mitigation is imposed, a mitigation is not followed, or a site is unidentified 

prior to the activity.

Idle Structure Removal

As per NTL 2010-G05 (“Decommissioning Guidance for Wells and Platforms”) (idle iron 

initiative), idle and toppled oil and gas industry-related structures embedded in the seafloor, 

including single-leg caissons, multi-legged jacketed fixed platforms, floating platforms secured by 

suction pilings, and subsea well-head and manifold systems, must be decommissioned and 

removed. Depending on water depth, seafloor characteristics, and vessel availability, an anchored 

barge, moored barge, or liftboat may be used. Additionally, the site must be cleared of debris to a 

radius of 600 or 1,320 ft (183 or 402 m) depending on the structure type and use. Clearance may be 

carried out by trawling or by sonar and diving operations. As of 2013, BOEM may require, as a 

condition of approval for a decommissioning permit, an archaeological survey in advance of 

structure-removal activities when no preexisting survey of the area of potential effect exists. Impacts 

to archaeological resources from structure-removal activities range from negligible to major if no 

survey is performed, no mitigation is imposed, a mitigation is not followed, or a site is unidentified 

prior to the activity.

To mitigate potential adverse impacts to archaeological resources, BOEM requires 

archaeological reconnaissance survey of all areas impacted by bottom-disturbing activities and 

avoidance or other actions, up to and including full Phase III excavation, of all potential 

archaeological resources within the identified area of potential effect of the undertaking. 

Archaeological surveys are expected to be effective at identifying possible archaeological sites. The 

technical requirements of the archaeological resource reports are detailed in NTL 2005-G07, 

“Archaeological Resource Surveys and Reports.” Under 30 CFR § 550.194(c) lessees are required 

to immediately notify BOEM’s Regional Director of the discovery of any potential archaeological 

resources. Under 30 CFR § 250.194(c) and 30 CFR § 250.1010(c), lessees are also required to 

immediately notify BOEM’s and BSEE’s Regional Directors of the discovery of any potential 

archaeological resources.

4.13.2.2 Accidental Events

Accidental impact-producing factors associated with a proposed action that could affect 

archaeological resources include accidental oil spills and loss of debris from a vessel or structure.
Description of the Affected Environment and Impact Analysis 4-409

Accidental Oil Spills

Impacts on archaeological resources could occur as a result of an accidental oil spill. A 

major impact from an oil spill would be visual and chemical contamination of a historic coastal site, 

such as a prehistoric shell midden, historic fort, or lighthouse. Although such impacts may be 

temporary and reversible, cleaning oil from historic structures is by no means a simple or 

inexpensive process (e.g., Chin and Church, 2010). The major impacts to coastal archaeological 

sites from the Exxon Valdez spill in Alaska in 1989 were related to cleanup activities, such as the 

construction of helipads, roads, and parking lots, and to looting by cleanup crews rather than from 

the oil itself (Bittner, 1996). As a result, cultural resources were recognized as significant early in the

response to the Deepwater Horizon oil spill, and archaeologists were embedded in Shoreline 

Cleanup and Assessment Technique (SCAT) teams and consulted with cleanup crews.

An oil spill occurring and contacting a submerged archaeological resource is unlikely, given 

that oil released tends to rise quickly to the surface and that the average size of any spill would be 

small. However, if it occurred, an oil spill contacting a coastal archaeological resource is possible. 

As noted in Chapter 3.2.8.2.2, the use of dispersants is reasonably foreseeable. However, if 

dispersants are used, the impacts to archeological sites have not been quantified. Refer to the 

Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017) for an analysis of the potential 

impacts of a catastrophic oil spill on coastal and submerged archaeological resources.

The impacts to archaeological sites from oil spills and associated activities have not been 

quantified because of incomplete or unavailable information, which are discussed later in this 

resource chapter.

Loss of Debris from a Vessel or Structure

Another impact that could result from an accidental event is from the loss of debris from an 

MODU, platform, lay barge, etc. during offshore operations. Debris such as structural components 

(i.e., grating, wire, tubing, etc.), boxes, pallets, and other loose items can become dislodged during 

heavy seas or storm events and fall to the seabed. Similarly, thousands of joints of drill pipe are 

used during drilling operations, requiring regular transport out to the MODU via workboats. There is 

the potential to lose pieces of drill pipe during transfer operations or when “tripping pipe” in and out 

of the wellbore. Similar to the impacts noted under “Routine Activities” (e.g., pipeline movement and 

anchor damage), if lost drill pipe or debris were to fall onto an unknown archaeological resource, the 

resulting disturbance could destroy fragile materials, such as the hull remains and artifacts, and 

could disturb the site’s context and associated artifact assemblage. Additionally, lost material could 

result in the masking of actual archaeological resources or the introduction of false targets that could 

be mistaken in the remote-sensing geophysical record as historic resources. Impacts to 

archaeological resources from the loss of debris from a vessel or structure range from negligible to 

major. 
4-410 Gulf of Mexico Multisale EIS

4.13.2.3 Cumulative Impacts

In addition to the cumulative impacts of the OCS Program whose impacts are the same as 

described above, the cumulative scenario activities that could potentially impact archaeological 

resources include (1) oil spill and response, (2) State oil and gas programs, (3) sand extraction, 

(4) artificial reef development, (5) fairway and anchorage use and maintenance, (6) commercial 

bottom trawling (fishing), (7) treasure hunting/looting, (8) sport diving, (9) research and monitoring, 

and (10) hurricanes. The chance that a localized cumulative scenario activity could impact any 

particular archaeological resource on the OCS is negligible (archaeological resources cannot be 

considered as a population); therefore, if a cumulative scenario activity were to impact an 

archaeological resource, it would constitute the primary impact to that resource. Consequently, this 

analysis identifies the range of potential impact levels to a particular archaeological site from specific 

cumulative scenario activities if the impact were to occur.

OCS Oil- and Gas-Related Impacts

Oil Spill and Response

Oil spills in the GOM range from sub-seafloor contained production casing leaks to 

environmentally damaging well blowouts to shipping accidents. There have been seven significant 

oil spills in the GOM, including accidents in State and Mexican waters: Ixtoc (1979); Burmah Agate 

(1979); Alvenus (1984); Megaborg (1990); Ocean 255 (1993); the aggregation of the effects of 

Hurricane Katrina (2005) (USDOC, NOAA, n.d.); and Deepwater Horizon/Macondo (2010). Activities 

associated with oil spills that may affect archaeological resources include anchoring of response 

vessels, drilling relief wells, the application of chemical dispersant, and the distribution of oil. Due to 

the emergency nature of oil spills, an archaeological survey is not feasible before related activities 

take place. The impacts to archaeological sites from oil spills and associated activities have not 

been quantified. 

Non-OCS Oil- and Gas-Related Impacts

State Oil and Gas Programs

State oil and gas program wells, structures, and pipelines in State waters are not under the 

jurisdiction of BOEM with respect to the archaeological resource protection requirements of the 

NHPA. Under the NHPA, other Federal agencies (such as the COE) that issue permits associated 

with pipelines in State waters are responsible for taking into consideration the effects of agencypermitted actions on archaeological resources. Therefore, the impacts that might occur to 

archaeological resources by pipeline construction originating from OCS oil- and gas-related activity 

within State waters should be mitigated under the requirements of the NHPA, and the same 

archaeological surveys for planned pipelines that lead into a landfall or a tie-in to a pipeline in State 

waters are required. Impacts to archaeological resources from State oil and gas program activities 

range from negligible to major if no survey is performed, no mitigation is imposed, a mitigation is 

not followed, or a site is unidentified prior to the activity. 
Description of the Affected Environment and Impact Analysis 4-411

Sand Extraction

Impacts to archaeological resources as a result of sand extraction activities include direct 

contact of a resource by the dredge head or anchors, redepositing of artifacts into the dredge 

disposal area, sediment transport and/or seabed destabilization around wrecks adjacent to the 

dredge pit, and direct contact of terrestrial or submerged resources in the dredge disposal area. The 

OCS sand resources have been identified off the coasts of Mississippi, Louisiana, and Texas in the 

following OCS areas: High Island; West Cameron; Vermilion; South Marsh Island; Eugene Island; 

Ship Shoal; South Pelto; West Delta; Chandeleur; and Main Pass. An archaeological review is 

required in advance of sand extraction activities. A current/ongoing BOEM study is quantifying the 

impacts to archaeological resources from sand extraction to incorporate into future sand extraction 

permit application review. Impacts to archaeological resources from sand extraction activities range

from negligible to major if no survey is performed, no mitigation is imposed, a mitigation is not 

followed, or a site is unidentified prior to the activity.

Artificial Reef Development

Artificial reef areas are designated by the COE for the disposal of decommissioned vessels, 

platform jackets, and other materials in order to promote and enhance biological systems. Potential 

impacts to archaeological resources include direct contact of the resource by the reefed material. 

Reefing areas are typically developed in <600 ft (183 m) of water; however, two fixed platform 

jackets have been reefed in place offshore Louisiana in water depths 620 and 650 ft (189 and 

198 m). Nine additional fixed platforms that range in water depths of 650-1,350 ft (198-411 m) are 

currently being considered for reefing in place by State-managed artificial reef programs (Texas, 

Louisiana, and Alabama). In addition to the State-managed programs, there are old artificial reefs 

and disposal areas that are not included in a State-managed program; these areas have not been 

quantified. The COE does not consistently require archaeological survey in advance of reef 

permitting. Most sonar and multibeam surveys by the State artificial reef programs are conducted 

after artificial reef deployments to verify placement. The area of potential effect of reefing activities 

also includes the anchor radius of tow and placement barges, which often extends outside of the 

reefing area. Impacts to archaeological resources from artificial reef development activities range 

from negligible to major if no survey is performed, no mitigation is imposed, a mitigation is not 

followed, or a site is unidentified prior to the activity.

Fairway and Anchorage Area Use and Maintenance

Fairways and anchorage areas are established to provide safe approaches to major ports in 

the GOM. Fairways and anchorage areas regulate allowable oil and gas industry and other activities 

within them, such as installation spacing, anchor and cable depth, pipeline burial, etc. Proper aids to 

navigation must be affixed to the seafloor. Fairways may be dredged to maintain safe water depths 

for navigation. An archaeological survey may not have been required in advance of fairway and 

anchorage area designation. Impacts to archaeological resources from fairway and anchorage area 

use and maintenance range from negligible to major if no survey is performed, no mitigation is 

imposed, a mitigation is not followed, or a site is unidentified prior to the activity.. 
4-412 Gulf of Mexico Multisale EIS

Commercial Bottom Trawling (Fishing)

Commercial bottom trawling may make use of nets, rakes, or dredges to harvest 

commercially important benthic organisms (e.g., shrimp, oysters, etc.). An archaeological survey 

and review has never been required in advance of the development of a commercial bottom trawling 

fishery in the GOM. Geophysical and diver inspection surveys have shown that trawling 

apparatuses have negligible to fully destructive impacts to submerged archaeological resources

depending on the resources composition and integrity (Steinmetz, 2010). For example, a shrimp net 

may snag and remain attached to the hull of a 20th-century steel vessel, while a shellfish rake or 

dredge may obliterate a 19th-century wooden sailing vessel leaving little to no trace of it on the 

seafloor. Impacts to archaeological resources from commercial bottom trawling range from 

negligible to major. There is no archaeological mitigation applied to commercial fishing.

Treasure Hunting/Looting

Treasure hunting involves the intentional, nonscientific, usually commercial exploitation of 

archaeological resources for profit. Often, specific shipwrecks are targeted for salvage. It is 

unknown how many archaeological sites have been salvaged by treasure hunters in the GOM. Two 

recent examples of commercial treasure hunting in the Gulf of Mexico OCS are the salvage of the 

New York (Gearhart et al., 2011; Irion and Ball, 2001; Bowers, 2008) and El Cazador

(www.elcazador.com). Looting involves the planned or opportunistic removal of artifacts or features 

from an archaeological site. It may range from the collection of mobile surface artifacts to the 

complete destruction and/or removal of the vessel. An example of the looting of an archaeological 

site was the attempted collection and destruction of artifacts on the shipwreck known as the Mardi 

Gras wreck during an remotely operated vehicle pipeline inspection (Ford et al., 2008). Impacts to 

archaeological resources from commercial treasure hunting/looting range from moderate to major. 

There is no archaeological mitigation applied to treasure hunting/looting.

Sport Diving

Sport diving includes private or commercial recreational diving on archaeological sites for 

pleasure and education. Negative impacts to archaeological sites from sport diving may result from 

boat anchor and mooring damage, disturbance to and removal (looting/souvenir hunting) of artifacts, 

intentional and unintentional physical contact (body or equipment), and the interaction of exhaled air 

bubbles with the site (Edney, 2006). Sport divers may, however, have a beneficial impact to 

archaeological sites by monitoring sites, encouraging fellow divers to protect sites, and by reporting 

any observed adverse impacts to the appropriate State or Federal agency. Impacts to 

archaeological resources from sport diving range from beneficial to major. There is no 

archaeological mitigation applied to sport diving.

Research and Monitoring

Research and monitoring activities in the GOM are not quantified; however, it is possible to 

discuss a potential range of impacts to archaeological sites from them. Negative impacts to 

archaeological sites may result from seafloor disturbance such as specimen collection by bottom 
Description of the Affected Environment and Impact Analysis 4-413

trawling or geotechnical core sampling. Beneficial impacts may result from the visual identification 

and/or inspection of sites during ancillary scientific activities or the collection of environmental data 

that may be used to evaluate the condition of archaeological sites. Impacts to archaeological 

resources from research and monitoring range from beneficial to major. Archaeological mitigation

may be recommended for research and monitoring if BOEM is (1) aware of the project and (2) is 

provided the opportunity to comment on the research design.

Hurricanes

Hurricanes and tropical storms are normal occurrences in the GOM and along the Gulf 

Coast. Shipwrecks in shallow waters are exposed to storm-induced wave action and a greatly 

intensified, longshore current during tropical storms (Clausen and Arnold, 1975). Under such 

conditions, there is a potential for hull components and artifacts (e.g., ceramics and glass) to be 

dispersed. Overall, a significant loss of data from sites has probably occurred, and would continue 

to occur, in the northern Gulf from the impacts of tropical storms. Impacts to archaeological 

resources from hurricanes range from negligible to major. BOEM does not apply any 

archaeological mitigation in advance of potential hurricane activity.

4.13.2.4 Incomplete or Unavailable Information

There is incomplete or unavailable information regarding the long-term impacts of oil, 

dispersed oil, and/or dispersant contamination on, and the location of, archaeological resources in 

the GOM. As discussed above, there are currently no published studies on the long-term impacts to 

archaeological resources exposed to oil, dispersed oil, or dispersant contamination. However, 

considering the low probability of an accidental oil spill contacting an archaeological site as a result 

of a proposed action, BOEM has determined that the information is not essential to a reasoned

choice among alternatives.

Additionally, the locations of all archaeological resources in the GOM cannot be determined 

because the overall costs of obtaining that information through survey of the entire GOM are 

exorbitant. This incomplete information may be relevant to adverse impacts because the locations 

and integrity of many archaeological resources remain unknown. Nevertheless, this incomplete 

information is not likely to be available within the timeline contemplated in the NEPA analysis of this 

Multisale EIS. It would take many years before data confirming the presence (or lack thereof) of 

archaeological resources, and the status of each, could be investigated, analyzed, and compiled. 

Archaeological sites within the GOM have the potential to be buried, embedded in, or laying on the 

seafloor. The seafloor is comprised of highly variable bathymetric and geophysical regimes, which 

differentially affect the ease and ability to identify, ground truth, and evaluate archaeological sites. 

This fact, combined with the scope of the acreage within the GOM, results in the aforementioned 

exorbitant costs and time factors.

BOEM used existing information and reasonably accepted scientific theories on 

archaeological site potential in the Gulf of Mexico to extrapolate from available information in 

completing the relevant analysis. In addition, future site-specific, remote-sensing surveys of the 
4-414 Gulf of Mexico Multisale EIS

seafloor, where required, establish the presence of potential resources (NTL 2005-G07, 

“Archaeological Resource Surveys and Reports”). The results of these surveys are reviewed in 

tandem with credible scientific evidence from previously identified sites, regional sedimentology, and 

physical oceanography that is relevant to evaluating the adverse impacts on resources that are a 

part of the human environment. The survey data are analyzed by industry and BOEM’s 

archaeologists prior to the authorization of any new or significant bottom-disturbing impacts and, if 

necessary, avoidance of potential archaeological resources is prescribed. Archaeological surveys 

are expected to be effective in identifying resources to allow for mitigation application and protection 

of the resource during OCS oil- and gas-related activities. A proposed action is not expected to 

have a reasonably foreseeable significant impact because BOEM’s evaluation of such impacts is 

based upon pre-disturbance and site-specific surveys, the results of which BOEM uses to require 

substantial avoidance of any potential resource that could be affected by the proposed activity. 

Therefore, BOEM has determined that the gaps in information on the presence of or status of 

archaeological resources is not essential to a reasoned choice among alternatives at the lease sale 

stage. 

4.13.2.5 Alternatives A, B, C, and D

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

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

alternatives is site specific and would result from direct contact between an offshore activity (i.e., 

platform installation, drilling rig emplacement, decommissioning, or dredging or pipeline project) and 

a site. During postlease activities, each permitted action would be assessed for site-specific 

potential impacts during the permit application process. Archaeological surveys, where required 

prior to an operator beginning OCS oil- and gas-related activities on a lease, are expected to be 

effective at identifying possible archaeological sites. The technical requirements of the 

archaeological resource reports are detailed in NTL 2005-G07, “Archaeological Resource Surveys 

and Reports.” Under 30 CFR § 250.194(c) and 30 CFR § 250.1010(c), lessees are required to 

immediately notify BOEM’s and BSEE’s Regional Directors of the discovery of any potential 

archaeological resources.

Offshore oil- and gas-related activities resulting from a proposed action could impact an 

archaeological resource because of incomplete knowledge on the location of these sites in the Gulf 

of Mexico. The risk of contact to archaeological resources is greater in instances where 

archaeological survey data are unavailable. Such an event could result in the disturbance or 

destruction of important archaeological information. Archaeological surveys would provide the 

necessary information to develop mitigation strategies that would reduce the potential for impacts on 

archaeological resources.

Accidental events producing oil spills may threaten archaeological resources along the Gulf 

Coast. Should a spill contact an archaeological site, damage might include direct impact from 

oil-spill cleanup equipment, contamination of materials, and/or looting. A major effect from an oilspill impact would be contamination of a historic coastal site, such as a historic fort or lighthouse. It 
Description of the Affected Environment and Impact Analysis 4-415

is expected that any spill cleanup operations would be considered a Federal action for the purposes 

of Section 106 of the NHPA and would be conducted in such a way as to minimize to the extent 

possible impacts to archaeological resources. Recent research suggests the impact of direct 

contact of oil on historic properties may be long term and not easily reversible without risking 

damage to fragile historic materials (Chin and Church, 2010).

The potential for spills is low, the impacts of most noncatastrophic spills would generally be 

localized, and the cleanup efforts would be regulated. A proposed action, therefore, is not expected 

to result in impacts to archaeological sites; however, should such impacts occur, unique or 

substantial archaeological information could be lost and this impact could be irreversible.

There is also the potential for debris from vessels and offshore structures to be lost on the 

OCS. Debris resulting from accidental events could lead to impacts similar to those expected from 

routine impacts such as damage through contact with historic archaeological sites and/or the 

masking of archaeological resources during geophysical surveys.

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

proposed action, including the drilling of wells and installation of platforms, installation of pipelines, 

anchoring, removal of platforms and other structures installed on the seafloor, and site clearance

activities without archaeological review and mitigation may result in major impacts to archaeological 

sites. Identification, evaluation, and avoidance or mitigation of archaeological resources is expected 

to result in negligible long-term cumulative impacts to archeological resources as described in the 

previous section; however, if an archaeological site were to be impacted, impacts may range from 

negligible to major. 

4.13.2.6 Alternative E—No Action

If selected, Alternative E, the No Action Alternative, would result in BOEM not undertaking a 

proposed lease sale. Therefore, the impact-producing factors mentioned above would not take 

place, and any impact that these actions could cause would not occur. As a result, whatever 

archaeological resources may be present would not be affected in any way if the No Action 

Alternative is selected.

4.14 HUMAN RESOURCES AND LAND USE

4.14.1 Land Use and Coastal Infrastructure

For land use and coastal infrastructure, a proposed action would involve all of the Gulf Coast 

States: Texas; Louisiana; Mississippi; Alabama; and Florida. Particular emphasis is placed on the 

133 counties and parishes that constitute the 23 BOEM-identified Economic Impact Areas (EIAs) 

and are located in the coastal areas of all five Gulf Coast States. This geographic area is broadly 

diverse in types of land use and distribution of coastal infrastructure related to OCS oil- and 

gas-related activities. Some counties and parishes are more closely connected to the offshore oil 
4-416 Gulf of Mexico Multisale EIS

and gas industry than others, such as Harris County, Texas, and Lafourche Parish, Louisiana. 

Figures 3-9, 3-11, and 3-12 illustrate the analysis area’s key infrastructure.

Impacts to land use and coastal infrastructure may be positive as well as negative. For 

example, increased economic demand for services provided by infrastructure facilities would lead to 

more hiring, and this additional employment would further the positive economic trend as new 

workers spend their wages in the community. The impacts of each impact-producing factor for 

Alternatives A-D are summarized in Table 4-31 to help the reader quickly identify the level of 

potential impacts for each impact-producing factor using the impact-level definitions below. The 

affected environment and analyses supporting these conclusions are then discussed in detail in this 

chapter. BOEM has concluded that the selection of Alternative E would result in negligible impacts. 

Cumulative impacts of current and past activities, however, would continue to occur under 

Alternative E.

Impact-Level Definitions

• Beneficial – Positive impacts in the form of maintaining current employment

levels, creating new employment, indirect and induced positive impacts through 

increased spending, and stimulating local and regional economies.

• Negligible – Little or no measureable adverse impact.

• Minor – Small-scale measurable adverse impact, temporary in duration and 

geographically small area (less than county/parish level).

• Moderate – Medium-scale measurable adverse impact and may last from a few 

weeks to 1 year and geographically may affect multiple counties/parishes.

• Major – Large-scale measurable or potentially unmeasurable adverse impact, 

long-lasting (1 year to many years), and may occur over a geographically large 

regional area.

A current snapshot of land use and coastal infrastructure in the GOM reveals a diverse social 

and economic landscape, with the oil and gas industry playing a substantially larger role in some 

states (i.e., Texas and Louisiana) than in the rest of the GOM. The oil and gas industry has 

developed across the region over many decades and is intimately intertwined with its socioeconomic 

structure. This complex structure involves offshore (i.e., on the Federal OCS and in State waters) 

and onshore (i.e., on private land and State and Federal onshore lands) exploration, development, 

and production activities, complicating the environmental impact analysis because it is very difficult, 

if not impossible, to separate the impacts of Federal OCS oil- and gas-related activities from those of 

oil and gas activities in State waters and onshore, or foreign imports.

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

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

providing a wealth of services from construction facilities, service bases, and waste disposal facilities 

to crew, supply, and product transportation, as well as processing facilities. Chapter 3.1.7
Description of the Affected Environment and Impact Analysis 4-417

discusses coastal infrastructure scenario projections, and Chapter 3.1.5.3 discusses onshore waste 

disposal. A description of the affected environment covers land use in the area and different 

infrastructure categories that support thousands of jobs. These jobs represent direct, indirect, and 

induced economic impacts that ripple through the Gulf Coast economy. As a long-standing part of 

the regional economy that developed over the past several decades, the coastal infrastructure 

network is quite mature in the Gulf of Mexico region. The affected environment is described in the 

following chapter and a discussion of the impacts of routine activities, accidental events, and 

cumulative impacts as they relate to land use and coastal infrastructure follows.

Table 4-31. Land Use and Coastal Infrastructure Impact-Producing Factors That Are Reasonably 

Foreseeable. 

Land Use and 

Coastal Infrastructure Magnitude of Potential Impact1

Impact-Producing 

Factors Alternative A Alternative B Alternative C Alternative D Alternative E

Routine Activities

Changes in the Level 

of OCS Exploration, 

Development, and 

Production Activities

Negligible to Negligible to Negligible to Negligible to

Negligible

Moderate Moderate Moderate Moderate

Expansions of Existing 

Infrastructure

Minor to Minor to Minor to Minor to

Negligible Moderate Moderate Moderate Moderate

New Infrastructure

Facility Construction

Minor to Minor to Minor to Minor to

Negligible Moderate Moderate Moderate Moderate

Onshore Waste 

Disposal 

Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Navigation Channel 

Maintenance Dredging

Negligible to Negligible to Negligible to Negligible to Negligible Minor Minor Minor Minor

Accidental Events

Oil Spills (coastal and 

offshore)

Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Chemical/Drilling-Fluid 

Spills

Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Spill Response Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Vessel Collisions Negligible to Negligible to Negligible to Negligible to Negligible Moderate Moderate Moderate Moderate

Cumulative Impacts

Incremental 

Contribution2 Minor Negligible

OCS Oil and Gas3 Beneficial to

Moderate

Non-OCS Oil and 

Gas4

Beneficial to

Major
4-418 Gulf of Mexico Multisale EIS

1 The analysis supporting these conclusions is discussed in detail in the “Environmental Consequences” 

chapter below.

2 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) as a result of a single proposed lease sale in the 2017-2022 Five-Year Program.

3 This includes all activities (i.e., routine activities projected to occur and accidental events that could 

occur) from past, proposed, and future lease sales.

4 This includes other past, present, and reasonably foreseeable future activities occurring within the same 

geographic range and within the same timeframes as a proposed action, but they are not related to the 

OCS Oil and Gas Program.

4.14.1.1 Description of the Affected Environment

Along the Gulf Coast, from the southern tip of Cameron County, Texas, to the Florida Keys, 

23 BOEM-defined EIAs are identified for the Gulf of Mexico region. The counties and parishes that 

form the EIAs are listed and the EIAs are visually illustrated on Figure 4-28. The EIAs 

geographically link together not only counties and parishes immediately adjacent to the GOM but 

also those tied to coastal counties and parishes as parts of functional economic areas. An analysis 

that encompasses where people live as well as where they work permits a more meaningful 

assessment of the impact of offshore oil and gas activities. The OCS oil- and gas-related activities 

draw on existing infrastructural, economic, and labor capacity from across the GOM region. BOEM’s 

analysis considers the potential impacts in all 23 EIAs regardless of where a proposed action may 

take place.

4.14.1.1.1 Land Use

The coastal zone of the GOM is not a physically, culturally, or economically homogenous unit 

(Gramling, 1984). The counties and parishes along the Gulf Coast represent some of the most 

valuable coastline in the U.S. and cover approximately 1,631 mi (2,625 km). Not only does it include 

miles of recreational beaches and an extended system of barrier islands, but it also has deepwater

ports, oil and gas support industries, manufacturing, farming, ranching, and hundreds of thousands 

of acres of wetlands and protected habitat. These counties and parishes vary in their histories and 

in the composition and economic activities of their respective local governments.
Description of the Affected Environment and Impact Analysis

4-419

Figure 4-28. Economic Land Use Patterns.
4-420 Gulf of Mexico Multisale EIS

The Gulf coastal plain of Texas makes up most of eastern and southern Texas and 

constitutes more than one-third of the State. Near the coast, this region is mostly flat and low-lying. 

It rises gradually to 1,000 ft (300 m) farther inland, where the land becomes more rolling. Belts of 

low hills occur across the Gulf coastal plain in many areas. In the higher areas, the stream valleys 

are deeper and sharper than those along the coast. Texas’ coastline along the GOM is 367 mi 

(591 km). However, long narrow islands called barrier islands extend along the coast; if the 

shoreline of all the islands and bays is taken into account, the coastline is 3,359 mi (5,406 km) long. 

The region is made up of farmland (i.e., cotton, rice, and citrus fruit), forests, cattle ranches, major 

cities of commerce (e.g., Houston) and education, tourist locales (e.g., South Padre Island), Federal 

installations (e.g., Lyndon B. Johnson Space Center), and major ports. The oil and gas industry has 

also been part of the local economies since the early 1900’s. Today, the majority of oil and gas 

corporations have headquarters in Houston while numerous industries associated with oil and gas 

(i.e., petrochemicals and the manufacture of equipment) are located in the area. In addition to oil 

and gas, the area has aggressively pursued technology companies such as computers and 

aerospace. The military has had a significant presence in general, particularly in the Corpus Christi 

Bay area and in San Patricio County on the eastern shore of the bay (Petterson et al., 2008).

The Louisiana coastal area includes broad expanses of coastal marshes and swamps 

interspersed with ridges of higher well-drained land along the courses of modern and extinct river 

systems. Most of the urban centers in coastal Louisiana are located along major navigable rivers 

and along the landward edge of the coastal zone (i.e., Lafayette and Lake Charles). Southwestern 

Louisiana is Acadian country. The area’s natural features vary from marshland, waterways, and 

bayous in the coastal areas to flat agricultural lands in the northern part of the same parishes. While 

the area’s traditionally strong ties to agriculture, fishing, and trapping are still evident, they are no 

longer the mainstay of the economy. Southeastern Louisiana, from Jefferson Parish east to 

St. Tammany Parish and the State border with Mississippi, is a thriving metropolitan area with 

shipping, navigation, U.S. Navy facilities, and oil and chemical refineries, all vying with local 

residents for land (Petterson et al., 2008). Historically, Terrebonne, Plaquemines, and Lafourche 

Parishes have been the primary staging and support area for offshore oil and gas exploration and 

development. The Port of Fourchon, at the mouth of Bayou Lafourche on the GOM, is a major 

onshore staging area for OCS oil- and gas-related activities in the GOM, and it is the headquarters 

of the Louisiana Offshore Oil Port (LOOP), which offloads 10 percent of U.S. foreign oil imports and 

transports that oil to half of the Nation’s refining capacity and services over 90 percent of deepwater

GOM production (The Greater Lafourche Port Commission, 2015). The LOOP has received and 

transferred over 11 billion barrels of crude oil since its inception (LOOP LLC, 2015).

Coastal Mississippi is characterized by bays, deltas, marshland, and waterways and is 

comprised of Hancock, Harrison, and Jackson Counties. Two-thirds of this 44-mi (71-km) coastline 

is devoted to State-chartered gambling and heavy tourism along the beachfront. The remaining onethird (Jackson County) is industrial—oil refining and shipbuilding. Upland portions of the three 

coastal counties are timberlands (Petterson et al., 2008). Offshore barrier islands form part of the 

Gulf Islands National Seashore, providing tourists with beaches to enjoy, trails to hike, and many 

fishing opportunities. Jackson County has a strong industrial base and designated industrial parks. 
Description of the Affected Environment and Impact Analysis 4-421

Pascagoula, in Jackson County, is home to Ingalls Shipbuilding, an 800-ac (324-ha) shipyard that 

employs 11,000 people, and the Chevron Pascagoula Refinery located in the Bayou Casotte 

Industrial Park (Ingalls Shipbuilding, 2015; Chevron, 2015). The Port of Pascagoula is one of the top 

20 ports in the U.S. by foreign cargo volume, handling forest products, chemicals, crude oil, 

phosphate rock, and aggregate. The port includes the Pascagoula River Harbor and the Bayou 

Casotte Harbor (Port of Pascagoula, 2015). Now in a state of expansion after recovering from 

Hurricane Katrina damages, the Port of Gulfport houses some major OCS oil- and gas-related

companies (i.e., shipbuilding, shipyards, pipelaying, and offshore support services) in addition to 

food importers, casino operations, university research activities, and renewable energy interests 

(Port of Gulfport, 2016).

Southwestern Alabama’s coastline is comprised of Mobile and Baldwin Counties, which 

oppose each other across Mobile Bay. The coastal plain of Alabama is characterized by beaches, 

wetlands, bayous, coastal bays, rivers, and estuaries. The only barrier island in Alabama, Dauphin 

Island, is populated with residences, businesses, and hotels. Coastal resource-dependent industries 

in this area include navigation, tourism, marine recreation, commercial fishing, and offshore natural 

gas development and production. Large quantities of natural gas were discovered in Alabama’s 

offshore waters in 1979. Baldwin County has a strong tourism economy and a large retiree 

population. The important commercial fishing industry in the area is located in southeastern Mobile 

County. The Port of Mobile, the largest seaport in Alabama, is also in Mobile County. The military 

has had a long presence in the area. The buildup and downsizing of military installations has 

handed the area some special challenges. The area’s second port, Mobile Middle Bay Port, is a 

former Naval Station. Major manufacturers in Mobile include three paper mills, a German-owned 

chemical plant, and two large shipbuilding and repair yards (Petterson et al., 2008). Mobile County 

has a strong industrial base and designated industrial parks, especially at Theodore Industrial Park 

and Canal and the Alabama State Docks. In addition, Bayou La Batre in south Mobile County has 

many shipbuilding firms. Theodore, in Mobile County, has boat and helicopter facilities, and onshore 

supply bases to support drilling and production (Dismukes, 2011).

The GOM coastal area of Florida includes bays, beaches, estuaries, wetlands, an extensive 

barrier island system, and increasing concentrations of human settlement. This area ranges from 

heavily urbanized areas, such as Pensacola in Escambia County and Panama City in Bay County 

with shipping ports and Naval air bases, to scarcely populated areas along the coastal rim, such as 

the towns of Port St. Joe, Apalachicola, and Carrabelle in Gulf and Franklin Counties. The Florida 

Panhandle area has military, tourism, fishing, and ports as major components of the economy. The 

military has had a substantial presence in the Florida Panhandle since World War II. The four main 

military installations are Pensacola Naval Air Station, Eglin Air Force Base (Okaloosa County), 

Tyndall Air Force Base, and the Coastal Systems Station (Bay County). The three air bases use the 

northern GOM as a weapon-testing and training range. These bases were largely untouched by the 

downsizing of the military in the 1990’s and remain an important part of the Florida Panhandle 

economy. Tourism and recreation are extremely important to the area, along with both commercial 

and recreational fishing activities. The development of the Florida Panhandle as a major tourist area 

began in the mid-1930’s and grew rapidly after World War II, becoming what is now a key industry in 
4-422 Gulf of Mexico Multisale EIS

Onshore coastal infrastructure 

discussed in this chapter 

supports both OCS and nonOCS oil- and gas-related 

activities, complicating impact 

analysis for this resource.

the Florida Panhandle. “Sugar-white” beaches, fishing, other water-based activities, and natural 

habitats are key parts of the tourist attraction. In the Florida Panhandle, the commercial fishing 

industry employs several hundred people, who land millions of pounds of fish and shellfish annually 

(Petterson et al., 2008). Three major deepwater ports are Port of Pensacola, Port Panama City, and 

Port Tampa Bay. The Port of Pensacola is turning away from bulk container cargo and focusing on 

expanding operations to cater to the oil and gas industry, and new projects such as deep-sea pipe 

manufacturing have begun development (Offshore Inland, 2014; DeepFlex, 2014; Pensacola News 

Journal, 2014). Port Panama City served as an onshore support base for exploratory drilling in the 

GOM during the 1980’s before drilling was banned in most of the EPA. Since that time the Port has 

continued diversifying and has initiated the development of the Port Panama City Intermodal 

Distribution Center to attract more businesses to the area. Most of the Port handles bulk container 

cargo, seafood products, and some petroleum products (Dehart, 2013; World Port Source, 2015).

The U.S. Dept. of Agriculture’s Economic Research Service classifies counties (includes 

parishes) into economic types that indicate primary land-use patterns. According to the most recent 

statistics, most notably only 7 of the 133 counties in the analysis area are classified as farming 

dependent. Ten counties are defined as mining dependent, suggesting the importance of oil and 

gas development to these local economies. Manufacturing dependence is noted for another 

26 counties. Local school districts and public facilities, such as hospitals and prisons, are often the 

largest employers in sparsely populated rural areas. Thus, it is not surprising that 19 non-metro 

counties and 13 metropolitan counties are classified as government employment centers. Another 

21 counties have economies tied to service employment while 37 counties are considered 

nonspecialized. The Economic Research Service also classifies counties in terms of their status as 

a retirement destination, and of the 133 counties/parishes, 44 are considered major retirement 

destinations (U.S. Dept. of Agriculture, Economic Research Service, 2008). The varied land-use 

patterns are displayed in Figure 4-28. 

4.14.1.1.2 Coastal Infrastructure

The onshore coastal infrastructure is extensive, covers a 

wide-ranging area, supports development, and consists of 

thousands of large and small companies. These companies cover 

every facet of coastal and offshore industry activity, but for 

analysis purposes, these infrastructure types are organized into 

the following categories: construction facilities; support facilities; 

transportation; and processing facilities. More extensive 

information on OCS oil- and gas-related coastal infrastructure can 

be found in Chapter 3.1.7. 

Construction Facilities

The major players among construction facilities in the coastal GOM include platform 

fabrication yards (Chapter 3.1.7.1.1), shipbuilding and shipyards (Chapter 3.1.7.1.2), and pipecoating plants and yards (Chapter 3.1.7.1.3). These facilities’ service involves both onshore and 
Description of the Affected Environment and Impact Analysis 4-423

offshore (State and Federal OCS) oil and gas exploration, development, and production activities. 

Shipbuilding and shipyards may also be servicing the commercial and recreational fishing industry or 

the military. Impact analysis becomes more complex because of the difficulty inherent in trying to 

separate the impacts of OCS oil- and gas-related activities from non-OCS oil- and gas-related 

activities, given that they utilize the same critical coastal infrastructure. 

Support Facilities

The major support facilities in the coastal GOM (Chapter 3.1.7.2) include service bases and 

ports, waste disposal facilities, and natural gas storage facilities. State and Federal (both onshore 

and offshore) oil and gas exploration, development, and production activities utilize the same critical 

coastal support infrastructure. Other types of support sectors to the oil and gas industry that may 

have coastal facilities can include drilling contractors, geological and geophysical contractors, 

underwater contractors (divers and remotely operated vehicle equipment). Ports and service bases 

are also used for international and domestic import and export activities, and service other industries 

including commercial and recreational fishing, cruise ship terminals, and research vessels. Maritime 

military operations generally have their own ports and bases along the coast, but they may use 

community waste disposal facilities.

Transportation

The major forms of crew, supply, and product transportation include the following: heliports; 

coastal pipelines/pipeline landfalls/pipeline shore facilities; and coastal barging/barge terminals. 

These transportation services can involve both onshore and offshore (State and Federal OCS) 

exploration, development, and production activities. This complicates impact analysis because of 

the difficulty inherent in trying to separate the impacts of OCS oil- and gas-related activities from 

non-OCS oil- and gas-related activities, given that they utilize the same coastal infrastructure. The 

OCS product that is piped to shore facilities and terminals may be moved by barge up rivers or 

through the Gulf Intracoastal Waterway and major shipping channels to service bases. Critical to the 

success of service bases and port facilities are the railways and major interstates that traverse the 

areas along the inner margin of the coastal zone. There are nine interstate highways that access 

the regional area; however, there are numerous other highways into and across the analysis area. 

The most critical is Louisiana Highway 1 (LA Hwy 1) that provides the only link between Port 

Fourchon, Louisiana, and the rest of the Nation. Chapter 3.1.4 discusses transport and 

Chapter 3.1.7 provides more detail on coastal infrastructure.

Processing Facilities

The major forms of processing facilities in the coastal GOM (Chapter 3.1.7.3) include gas 

processing plants, LNG terminals, refineries, and petrochemical plants. Basic chemical production 

from petrochemical plants is concentrated along the Gulf Coast, where petroleum and natural gas 

feedstock are available from refineries. Of the top 10 production complexes in the world, 5 are 

located in Texas and 1 is located in Louisiana. These facilities can process onshore and offshore 

(State and Federal OCS) production and foreign imported production. This complicates impact 
4-424 Gulf of Mexico Multisale EIS

analysis because of the difficulty inherent in trying to separate the impacts of OCS oil- and 

gas-related activities from non-OCS oil- and gas-related activities, given that they utilize the same 

critical coastal infrastructure for downstream processing of their products.

4.14.1.2 Environmental Consequences

Analysis and discussion of impact-producing factors from routine activities, accidental events 

(non-catastrophic), and cumulative activities follow below. For a detailed analysis of a high-impact, 

low-probability catastrophic oil spill, which is not reasonably foreseeable as a result of a proposed 

action, refer to the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 2017).

4.14.1.2.1 Routine Activities

Routine activities of the oil and gas industry result in various impact-producing factors that 

could affect land use and coastal infrastructure, including the following: fluctuations in the level of 

OCS exploration, development, and production activities; expansions of existing facilities; 

construction of new facilities; onshore disposal of OCS waste; and maintenance dredging of existing 

navigation channels. These routine activities impact, to some extent, each of the infrastructure types 

discussed in the “Affected Environment” section above, including construction facilities, support 

services, transportation modes for people and products, and processing facilities Given that the 

oil- and gas-related coastal infrastructure is a mature and extensive system, resulting from long-term 

industry trends, it is not subject to rapid fluctuations. Routine activities related to a proposed action 

are expected to minimally affect the current land use of the analysis area because most subareas 

have strong industrial bases and designated industrial parks with existing infrastructure and facilities 

that have sufficient capacity to accommodate future growth. For this reason, land use conflicts from 

a single proposed lease sale are not likely to occur.

Fluctuations in OCS exploration, development, and production activity levels can impact land 

use and coastal infrastructure because higher activity levels increase demand for services, which 

can affect land use if a facility needs to acquire additional land for expansion to meet the demand, 

and it would affect infrastructure facilities by potentially increasing profits and the need to hire 

additional employees. This would be a positive impact and could cause localized expansion of 

economies (i.e., increased demand for services, consumer spending, and indirectly, new 

employment), resulting in localized land-use changes including commercial and residential 

development and growth. If activity levels decrease, then the opposite impact occurs. Decreases in 

demand for services could cause a negative ripple impact through the local (and possibly regional) 

economies. The OCS activity levels fluctuate based on changes in demand, commodity prices, and 

offshore service vessel day rates (for shipyards, shipbuilding, and transportation services). When 

activity levels increase, commuter and truck traffic increase, producing additional wear and tear on 

the transportation infrastructure. For example, in Louisiana, LA Hwy 1 is the only road providing 

critical access to Port Fourchon, the largest OCS oil- and gas-related service base, which supports 

90 percent of all OCS deepwater activities (World Oil, 2016; LA1 Coalition, 2016). A multi-phase 

LA Hwy 1 improvement project has been ongoing for several years and was approved for a 

$12.5-million additional Phase 2 funding in 2015 (LA1 Coalition, 2015) The impacts described 
Description of the Affected Environment and Impact Analysis 4-425

above range from negligible to moderate depending on the specific situation, type of infrastructure 

facility being considered, and its location. For example, a small-scale expansion of a facility located 

in a remote area would be a negligible impact. If the facility was located in a populated area, it may 

cause temporary disruption to traffic from construction activities and thus be a minor impact. If it 

was a larger-scale expansion and the facility was located in a more populated area, then the impact 

would be moderate because the scale of the project would make the disruption last anywhere from 

a few weeks to a year.

Land use and coastal infrastructure may also be affected by expansions of current facilities 

that result from oil and gas industry-generated service demand increases. Because of the 

environmental and regulatory difficulties inherent in permitting and building new facilities, most 

companies would opt to expand their existing facilities (i.e., fabrication yards, shipyards, pipe-coating 

facilities, service bases, refineries, gas processing plants, and waste disposal facilities). Expansions 

of existing facilities generate a positive momentum with increased capabilities leading to increased 

profitability. Whether positive or negative, the impacts described above range from facility 

expansions ranges from minor to moderate depending on the specific situation. For example, a 

small-scale expansion of a refinery would be a minor impact because of the small size of the 

project, the temporary disruptions caused by increased constructions traffic and the geographically 

small area affected. If the refinery was located in a more populated area and the project was larger 

in scale, causing disruptions because of construction activities that last up to one year, then the 

impact would be moderate. BOEM’s scenario projections forecast most increases in demand to be 

met by expansions at currently existing facilities (Dismukes, official communication, 2015).

Much less common in the GOM, the construction of new facilities requires substantial capital 

investment and assurances of future service demand to make this option attractive to investors. 

BOEM’s scenario projections call for possibly 0-1 new gas processing plant and 0-1 new pipeline

landfall during the 50-year analysis period for a proposed lease sale (Dismukes, official 

communication, 2015). If either were to occur, it may negatively impact land use because of 

potential space-use conflicts, and some existing gas processing facilities also could be negatively 

impacted because it may become necessary to increase efforts to maintain competitiveness. In the 

rare instance of new facility construction, the impacts would range from minor to moderate

depending on the nature and location of the project(s).

The OCS oil- and gas-related waste disposal to onshore facilities is an impact-producing 

factor that could affect onshore waste disposal facilities and land use if a new facility needs to be 

constructed to meet the level of offshore wastes coming to shore. Chapter 3.1.5.3 discusses OCS 

oil- and gas-related waste disposal and outlines BOEM’s scenario analysis, which concluded that no 

new solid-waste facilities would be built as a result of a single lease sale. Existing solid-waste 

disposal infrastructure is adequate to support both existing and projected offshore oil and gas drilling 

and production needs. The industry trend is toward innovative methods to handle wastes to reduce 

the potential for environmental impacts, e.g., hydrocarbon recovery/recycling programs, slurry 

fracture injection, treating wastes for reuse as road base or levee fill, and segregating waste streams 

to reduce treatment time and improve oil recovery. The volume of OCS waste generated is closely 
4-426 Gulf of Mexico Multisale EIS

correlated with the level of offshore drilling and production activity (Dismukes et al., 2007, Dismukes, 

2011, Dismukes, official communication, 2015). The impact of fluctuations in offshore waste 

disposal would range from negligible to minor and would not be expected to result in more 

extensive impacts because existing spare capacity of current facilities is sufficient to meet demand.

Maintenance dredging of existing navigation channels is essential for proper water depths to 

allow all shipping to move safely through the waterways to ports, services bases, and terminal 

facilities. Several million cubic yards of sand, gravel, and silt are dredged from waterways and 

harbors every year. Chapter 3.1.3.3.4 discusses scenario projections for navigation channels along 

the Gulf Coast. Much of the traffic navigating these channels is unrelated to OCS oil- and gasrelated activity, and the current system of navigation channels in the northern GOM is projected to 

be adequate for accommodating traffic generated by a proposed lease sale. Therefore, no new 

navigation channels are expected to be created as a result of a proposed lease sale (Dismukes, 

2011; Dismukes, official communication, 2015). Chapter 4.3.2 provides a discussion of wetlands

and the impacts of navigation channel dredging. Impacts to land use and coastal infrastructure as a 

result of maintenance dredging are expected to range from negligible to minor depending on the 

location of dredging projects.

Routine activities are not expected to produce any major impacts to land use and coastal 

infrastructure because current supporting oil and gas infrastructure is mature and not subject to rapid 

changes. As OCS oil- and gas-related activity levels fluctuate, the demand for services provided by 

coastal infrastructure facilities would fluctuate. If necessary, increases in demand would be met with 

facility expansions. Regarding new construction, BOEM’s scenario projections call for up to one new 

gas processing facility, up to one new pipeline landfall over the 50-year life of a proposed lease sale, 

and no new waste disposal facilities. The impacts on land use and coastal infrastructure would be 

limited, would occur on lands designated for such purposes, and would be negligible to moderate

because expansions at current facilities could cause either little or no measurable adverse impact 

(negligible) or may cause small-scale, temporary adverse impacts affecting a small area (minor). 

Impacts could possibly reach a moderate level if a new gas processing facility is installed sometime 

during the 50-year life of the lease because it could cause medium-scale impacts lasting up to a year 

and possibly affecting more than one county or parish. However, the likelihood of a future gas 

processing facility is closer to zero than the possible one projected. Maintenance dredging of 

navigation channels as a result of a proposed lease sale is expected to produce negligible to minor

impacts to land use and coastal infrastructure (Dismukes, official communication, 2015).

4.14.1.2.2 Accidental Events

Impact-producing factors associated with accidental events that may affect land use and 

coastal infrastructure include coastal and offshore oil spills, chemical/drilling fluid spills, spillresponse activities, and vessel collisions. Accidental events associated with a proposed action 

would occur at differing levels of severity, based in part on the location and size of event. Coastal 

and offshore oil-spill events discussed in this section are noncatastrophic in nature, smaller in size, 

occur more frequently, and must be distinguished from low-probability catastrophic oil spills such as 
Description of the Affected Environment and Impact Analysis 4-427

the Deepwater Horizon blowout, oil spill, and response. Chapter 3.2.1 provides a detailed 

discussion of oil spills that have occurred and their frequency. A complete analysis of a high-impact, 

low-probability catastrophic oil spill is provided in the Catastrophic Spill Event Analysis white paper 

(USDOI, BOEM, 2017).

Coastal and offshore oil spills may be associated with OCS exploration, production, or 

transportation activities that result from a proposed lease sale. Detailed risk analysis of offshore oil 

spills ≥1,000 bbl, <1,000 bbl, and coastal spills associated with a proposed lease sale is provided in 

Chapters 3.2.1.4, 3.2.1.5, and 3.2.1.6. Because spills <1,000 bbl are not expected to persist as a 

slick on the surface of the water beyond a few days and because spills on the OCS would occur at 

least 3-10 nmi (3.5-11.5 mi; 5.6-18.5 km) from shore, it is unlikely that any spills would make landfall 

prior to breaking up. The combined probabilities for an offshore spill ≥1,000 bbl occurring and 

contacting coastal and offshore areas for each alternative can be found in the figures in 

Appendix E. For a proposed action, the probabilities of an oil spill ≥1,000 bbl occurring and 

contacting the shoreline within 10 days range from <0.5-1 percent to 2-8 percent, with the highest 

probability in Plaquemines Parish, Louisiana, at 1-6 percent (Figure E-2). The probabilities of an oil 

spill ≥1,000 bbl occurring and contacting the shoreline within 30 days range from <0.5-1 percent to 

2-8 percent, with the highest probability in Plaquemines Parish, Louisiana, at 2-8 percent 

(Figure E-3). Oil spills in coastal and inland waters, such as spills resulting from the operations of 

offshore supply vessels, pipelines, barges, tanker ships, and ports, are more likely to affect land use

and coastal infrastructure categories. For example, if waterways are closed to traffic, this may result 

in impacts to upstream and downstream business interests as it impedes the flow of commerce. 

Other potential impacts could include damages to private and public lands, personal injury, damages 

to collateral property (moveable property such as vehicles and boats), and economic damages from 

the disruption of business. The impacts to land use and coastal infrastructure from coastal and 

offshore oil spills could range from negligible to moderate depending on the size and location of the 

spill. For more information on the potential impacts of a low-probability catastrophic spill (which is 

not part of a proposed action and not reasonably foreseeable as a result of a proposed action), refer 

to BOEM’s Catastrophic Spill Event Analysis technical report (USDOI, BOEM, 2017). More 

specifically, the intensity of the impact would be experienced inconsistently among businesses and 

residents, meaning it would be worse for some businesses/residents than others. For example, 

those who have alternative means of transporting their goods would not feel the impact as harshly 

as those who are most dependent on the waterway for transport. The mean number and sizes of 

spills estimated to occur in OCS offshore waters from an accident related to rig/platform and pipeline 

activities supporting a proposed action over a 50-year period are presented in Table 3-18. 

Chemical/drilling-fluid spills may affect land use and coastal infrastructure and could be 

associated with exploration, production, or transportation activities that result from a proposed lease 

sale. Chapter 3.2.6 provides a detailed discussion of chemical and drilling-fluid spills. Each year, 

between 5 and 15 chemical spills are expected to occur; most of these are ≤50 bbl in size. Large 

spills (≥1,000 bbl) are much less frequent but may be reasonably foreseeable and are therefore 

considered within this Multisale EIS; in contrast, a catastrophic event of a magnitude similar to the 

Deepwater Horizon explosion, oil spill, and response is not reasonably foreseeable and not part of a 
4-428 Gulf of Mexico Multisale EIS

proposed action. Even though additional production chemicals are needed in deepwater operations 

where hydrate formation is a possibility, offshore spill volumes are expected to remain stable 

because of advances in subsea processing. Spills may also occur during transport in coastal 

waters. Overall, the impact of chemical and drilling-fluid spills is expected to be negligible to 

moderate depending on the location, size, and duration of the event. For example, potential 

impacts could include damages to private and public lands, personal injury, damages to collateral 

property (moveable property such as vehicles and boats), and economic damages from the 

disruption of business. If a spill is very small (not measurable) in size, located in a remote area, and 

dissipates quickly, its impact would be negligible. If a spill is measurable, occurs in a less remote 

area, and lasts a few days to a month, then its impact would be minor. If a spill occurs in a highly 

populated area (e.g., Houston Ship Channel), is larger in quantity, and the response and cleanup 

last over a month and up to a year with either waterborne commerce affected and/or land 

transportation affected, then the impact would be moderate. 

While not an accidental event specifically, spill-response activity results from an accidental 

spill and therefore is included in this analysis. Spill-response activities may affect land use and 

coastal infrastructure because of the requisite needs for staging operations, equipment handling, 

and waste disposal. Depending on where an accidental event occurs, it is expected that the oil-spill 

response equipment needed to respond to an offshore spill as a result of a proposed lease could be 

called out from one or more of the following oil-spill equipment base locations: Aransas Pass, 

Baytown, Corpus Christi, Galveston, Houston, Ingleside, Pasadena, and Port Arthur, Texas; Baton 

Rouge, Belle Chasse, Fort Jackson, Franklin, Grand Isle, Harvey, Houma, Lake Charles, New Iberia, 

Port Fourchon, and Sulphur, Louisiana; Kiln and Pascagoula, Mississippi; Bayou La Batre and 

Mobile, Alabama; Key West, Miami, Panama City, Pensacola, and Tampa, Florida (Marine Spill 

Response Corporation, 2015b; National Response Corporation, 2015). The impact of spill-response 

activities on land use and coastal infrastructure would range from negligible to moderate

depending on the spill’s location, duration, and whether the event is a small-scale spill or a larger 

spill. For example, potential impacts could include space-use conflicts related to staging operations, 

potential mishandling of cleanup equipment (boom), and improper disposal of oily wastes. In 

addition, the additional use of waterways or roadways used for the vehicles servicing spill response 

may result in localized increased wear and tear.

Vessel collisions may be associated with exploration, production, or transportation activities 

that result from a proposed lease sale. Chapter 3.2.5 provides a detailed discussion of vessel 

collisions. The majority of offshore vessel collisions involve service vessels colliding with platforms 

or pipeline risers, although sometimes vessels collide with each other. In coastal waters, vessel 

collisions are more likely to include other vessels or stationary structures like bridges and docks. 

Human error accounted for about half of all reported vessel collisions from 1996 through 2009. 

These collisions often result in spills of various substances and, while most occur on the OCS far 

from shore, spills in coastal waters can have impacts to land use and coastal infrastructure that can 

range from negligible to moderate, depending on the severity and location of a vessel collision, the 

size of the vessels involved, and whether the collision involves a bridge, pier, or other structure. 
Description of the Affected Environment and Impact Analysis 4-429

Land use may be affected if a bridge, pier, or other structure is involved because it could affect the 

transportation of goods, services, and people to and from work and schools.

The impact of reasonably foreseeable oil spills, chemical and drilling-fluid spills, and vessel 

collisions are not likely to last long enough to adversely impact overall land use or coastal 

infrastructure in the analysis area. Spill-response impacts would depend on the location and 

duration of a spill.

4.14.1.2.3 Cumulative Impacts

Land use and coastal infrastructure experience cumulative impacts that include all human 

activities and natural processes and events. The cumulative analysis considers impacts that 

comprise the incremental contribution of a proposed lease sale combined with all past, present, and 

reasonably foreseeable future Federal OCS oil- and gas-related lease sales, considered along with 

the natural baseline conditions before the first lease sale in 1954, as well as all past, present, and 

reasonably foreseeable future actions unrelated to the Federal OCS oil- and gas-related activities 

(Chapter 3.3).

The cumulative analysis geographically includes all 133 counties that comprise the 

23 BOEM-identified EIAs, covering the coastal areas of all five Gulf Coast States from the southern 

tip of Texas to the Florida Keys. Temporally, the natural baseline conditions were those in existence 

before the first Federal OCS lease sale in 1954, several decades ago. At that time, population in the 

five Gulf Coast States was only 19.8 million, much less than half of the 60.3 million residents in 2015

(USDOC, Census Bureau, 2015a, 2015b, 2015c, 2015d, and 2015e) (Table 4-32).

Table 4-32. Comparison of the 1954 and 2015 Populations by State.

State 1954 2015 # Increase % Difference

Alabama 3,014,000 4,858,979 1,844,979 37.97%

Florida 3,505,000 20,271,272 16,766,272 82.71%

Louisiana 2,883,000 4,670,724 1,787,724 38.28%

Mississippi 2,064,000 2,992,333 928,333 31.02%

Texas 8,382,000 27,469,114 19,087,114 69.49%

Total 19,848,000 60,262,422 40,414,422 67.06%

Sources: USDOC, Census Bureau, 2015a, 2015b, 2015c, 2015d, and 2015e.

The coastal areas experienced the greatest proportion of population growth over the years 

(USDOC, NOAA, 2011). Though coastal areas were less developed and more rural in 1954 than 

they are now, there was much cultural variation across the region, especially in Louisiana (White, 

1998). The oil and gas industry had been thirving in Texas and Louisiana since 1901 with the 

Beaumont, Texas, Spindletop discovery and the first Louisiana oil well in Jennings (Austin et al., 

2008; Texas Almanac, n.d.; State of Louisiana, Dept. of Natural Resources, n.d.). All manner of oil 

and gas infrastructure developed over the decades from 1901 to 1954. The onshore oil and gas 

industry developed and matured, bringing many jobs and economic opportunity to the area. The 
4-430 Gulf of Mexico Multisale EIS

1950’s marked one of the most prosperous time periods for the United States, with more wealth 

being created from 1950 to 1965 than in any previous era (Arabe, 2003). When the Federal 

Government formalized its control over the OCS in 1953, the oil and gas industry was already 

booming onshore and in coastal waters along the Gulf Coast and had been for many decades.

The Submerged Lands Act and the OCSLA, both passed in 1953, laid the foundation for the 

creation of the Federal OCS Oil and Gas Leasing Program. The first lease sale of OCS lands in the 

Gulf of Mexico occurred on October 13, 1954. Since that time, in the Gulf of Mexico region, the 

Federal OCS Oil and Gas Program has held over 120 lease sales, leasing in excess of 143 million 

ac (58 million ha), with over $66 billion in total bonuses for leased blocks (USDOI, BOEM, 2016a). 

The past and present OCS Programs (with >120 lease sales) has occurred simultaneously with 

numerous non-OCS oil- and gas-related past and present activities that, when taken in their entirety, 

have resulted in the current make-up of the analysis area (refer to Figure 4-27 and “Description of 

the Affected Environment” above). BOEM adds to this all reasonably forseeable future OCS oil- and 

gas-related and non-OCS oil- and gas-related activities to complete the cumulative analysis within 

the geographical bounds of the 23 BOEM-identified EIAs spanning across 133 counties and 

parishes.

Incremental Contribution

Within this divided analytical framework of OCS oil-and gas-related and non-OCS oil- and 

gas-related impacts, the largest quantity of impact-producing factors for land use and coastal 

infrastructure occur as non-OCS oil- and gas-related impacts because these resources are located 

onshore and exist for the benefit of both offshore and onshore oil- and gas-related activities, as well 

as other societal and business needs. Land use and coastal infrastructure reside within an 

extremely complex socioeconomic structure, and offshore OCS oil- and gas-related activities 

comprise a very small portion of this structure. Therefore, the incremental contribution to cumulative 

impacts of a proposed action, i.e., a single proposed lease sale, would be minor for land use and 

coastal infrastructure in the Gulf Coast region.

OCS Oil- and Gas-Related Impacts

Potential impacts related to OCS oil- and gas-related activities include the cumulative impact 

of all past, present, and future lease sales, and the resultant exploration, development, and 

production in Federal waters that contribute to the following possible impacts: fluctuations in OCS 

oil- and gas-related activity levels; increases in commuter and truck traffic; onshore infrastructure

expansions; construction of new infrastructure facilities; increases in waste disposal volumes; 

coastal and offshore oil spills, chemical/drilling-fluid spills, spill-response activities, and vessel 

collisions, which are all discussed above under “Routine Activities” above. A proposed lease sale 

would make a minor incremental contribution to the cumulative impacts of all past, present, and 

future lease sales. 

The OCS oil- and gas-related onshore coastal infrastructure is extensive, covers a wideranging area, supports OCS development, and consists of thousands of large and small
Description of the Affected Environment and Impact Analysis 4-431

companies. Chapter 3.3.1.10 describes the cumulative coastal infrastructure scenario projections 

for the OCS Program. BOEM estimates no additional service bases, heliports, platform fabrication 

yards, shipyards, or pipe-coating yards. Lease sales would serve mostly to maintain ongoing 

activity levels associated with the current OCS Program. Industry would more or less maintain its

current usage of infrastructure. Expectations for new gas processing facilities being built during the 

70-year analysis period as a direct result of the OCS Program are dependent on long-term market 

trends that are not easily predicable over the next 70 years. Existing facilities would experience 

equipment switch-outs or upgrades during this time. BOEM projects that expansions at existing 

LNG facilities and the construction of new facilities would not occur as a direct result of the OCS 

Program. Cumulative impacts of OCS oil- and gas-related activities are dependent on fluctuations in 

OCS activity levels; increases in commuter and truck traffic; expansions at existing facilities; new 

construction of infrastructure; increases in waste disposal volumes; and accidental events such as 

coastal and offshore oil spills, chemical/drilling-fluid spills, spill-response activities, and vessel 

collisions. BOEM’s scenario projections call for the new construction of 0-1 new gas processing 

facility and 0-1 new pipeline landfall to result from a proposed lease sale over the analysis period. 

Increases in demand for services at other facilities would be met by current excess capacity or 

expansions at current facilities. These activities, along with noncatastrophic accidental events, are 

reasonably foreseeable. Cumulative impacts resulting from all past, present, and reasonably 

foreseeable future OCS oil- and-gas related activities could range from beneficial to moderate

depending on the specifics of each situation, whether the impacts are measurable, how long the 

impacts would last, and the size of the affected geographic area.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil and gas-related cumulative impacts encompass all human activities and natural 

processes that may affect land use and coastal infrastructure. A discussion of every conceivable 

human activity and natural process from a global or universal perspective would consume volumes 

and would not be a reasonable or realistic undertaking (e.g., international commodity markets, 

geopolitical agendas [OPEC], Zika virus, or asteroid strikes). Therefore, BOEM limits this cumulative 

analysis to the following most relevant (past, present, and reasonably foreseeable future) impactproducing factors:

• State oil and gas activity; 

• onshore oil and gas activities; 

• demands on transportation systems and ports;

• maintenance and improvements to transportation systems;

• construction and maintenance of industrial facilities;

• agricultural uses;

• urbanization;

• demographic shifts (i.e., in-migration and out-migration);
4-432 Gulf of Mexico Multisale EIS

• evolution of State and Federal regulations;

• city planning and zoning; 

• development of residential areas and recreational facilities;

• modifications to public facilities such as water, sewer, educational, and health

facilities; 

• military activities;

• coastal land loss;

• coastal storms; and

• global, national, and regional economic trends.

All of the cumulative non-OCS oil- and gas-related impacts discussed in this section can 

range across the scale, i.e., from beneficial to major adverse impacts depending on the unique 

specifics of each situation, whether the impacts are measurable, how impacts are measured, how 

long they would last, the size of the affected area, and most importantly, the viewpoints of the 

various people that may be involved. For example, in the case of urbanization, land developers 

would say any negative impacts are minor or negligible because they would be out-weighed by the 

beneficial economic benefits to the area (e.g., jobs, increased tax revenues), but a conservationist 

would say the impacts are major, negative, and highly detrimental because of habitat loss and 

damages to air and water quality. Given that within each listed category above there can be a 

myriad of potential situations that arise across the very large (133 counties and parishes) Gulf Coast 

analysis area, the discussion below does not assign individual labels (i.e., beneficial, negligible, 

minor, moderate, or major) to every category of cumulative impacts described.

Non-OCS oil- and gas-related activities onshore and in State waters utilize many of the same 

coastal infrastructure facilities as offshore OCS oil- and gas-related activities (Figure 3-9) and would 

continue to contribute to the cumulative impacts on land use and coastal infrastructure throughout 

the 70-year analysis period. Over the past several years, there has been a substantial decrease in

offshore natural gas production in shallow waters, partially as a result of increasing emphasis on 

onshore shale gas development, which is less expensive to produce and which provides larger

per-well production opportunities and reserve growth. Onshore unconventional natural gas

production has increased to the point that existing Gulf Coast LNG facilities are seeking, and some 

have started, to export natural gas to foreign consumers. For all coastal infrastructure types, 

especially processing facilities, it has proven impossible to parse out what percentage of demand is 

generated by OCS oil- and gas-related activities as opposed to non-OCS oil- and gas-related 

activities. This difficulty is an inherent problem in analyzing most cumulative impacts to coastal land 

use and infrastructure.

For example, demands on transportation systems and ports are not isolated to OCS oil- and 

gas-related activities. Transportation systems (e.g., rail, trucks, highways, barges, supply vessels, 
Description of the Affected Environment and Impact Analysis 4-433

and tankers) and ports also serve oil and gas activities onshore and in State waters, as well as other 

industrial uses unrelated to oil and gas activities (e.g., agricultural and manufacturing transport, and 

commercial and recreational fishing). The maintenance and improvements necessary for 

transportation systems and ports also are likely to cause cumulative impacts to land use and coastal 

infrastructure, in varying degrees, depending on the magnitude of each project. Similarly, 

construction or expansion and maintenance of non-OCS-related industrial facilities, such as paper 

mills and aluminum plants, could contribute to cumulative impacts on land use and coastal 

infrastructure depending on proximity and scale of the work being done.

Agricultural uses may also contribute to cumulative impacts on land use and coastal 

infrastructure. Of the over 400,000 mi2 (1,035,995 km2

) comprising these coastal states, 18 percent 

of the total land area is covered in cropland, which includes cropland harvested, crop failure,

cultivated summer fallow, cropland used only for pasture, and idle cropland. Texas and Mississippi 

have the highest percentages of cropland, with 20 percent and 19 percent of each respective 

state’s total land being used for cropland. Texas leads the Nation in cattle, cotton, hay, sheep, and 

wool. Texas also leads the Nation in the number of farms and ranches, with 247,500 farms and 

ranches covering 130.4 million ac (52.8 million ha). For all four coastal states, 42 percent of the 

total land area is used for grassland pasture and range, with Texas devoting 61 percent or close to

262,000 mi2 (679,095 km2

) for grassland pasture and range. Agriculture places many demands on 

the environment and produces impacts that include, but are not limited to, habitat fragmentation, 

pesticide and nutrient runoff, competing urban and agricultural water needs, changes to watershed

hydrology, and changes in soil quality. Both State and Federal entities regulate various farming 

and ranching practices through laws such as the Clean Water Act, which establishes pollutant 

standards for many of the inputs used in conventional farming methods (Lubowski et al., 2006).

Cumulative impacts of urbanization on land use and coastal infrastructure affect the Gulf of 

Mexico EIAs with the highest numbers of people. Demographic shifts as people move in and out of 

areas contribute to the cumulative impacts on land use and coastal infrastructure. Census urban

areas include densely populated areas with at least 50,000 people (“urbanized areas”) and 

densely populated areas with 2,500-50,000 people (“urban clusters”). Included in the Census 

urban area definition are residential areas and concentrations of nonresidential urban areas such as

commercial, industrial, and institutional land; office areas; urban streets and roads; major airports;

urban parks and recreational areas; and other land within urban defined areas. Development takes

the place of natural ecosystems and fragments habitat. It also influences decisions people make 

about how to get around and determines how much people must travel to meet daily needs. These

mobility and travel decisions have indirect impacts on human health and the natural environment 

by affecting air and water pollution levels. Impacts of urbanization include habitat fragmentation, 

reduced water and air qualities, and the urban heat island impact. On the other hand, residents of 

cities live in smaller homes and drive less because of the close proximity of amenities. Future

trends in urban land use would be largely determined by economics, demographic shifts, local

ordinances, and zoning (USEPA, 2013b).
4-434 Gulf of Mexico Multisale EIS

Within the geo-political realm, non-OCS related cumulative impacts on land use and coastal 

infrastructure could also include evolving State and Federal regulations (especially environmental), 

city planning and zoning, residential development, recreational facilities, public facilities (i.e., water, 

sewer, health, and education), and military activities. Land- use patterns vary greatly by region, 

reflecting differences in soils, climate, topography, and patterns of population settlement. Landuse changes would largely depend upon local zoning and economic trends. Mississippi and 

Louisiana are located in what the U.S. Department of Agriculture’s Economic Research Service

calls the Delta farm production region, while Alabama is located in the Southeast farm 

production region, and Texas is located in the Southern Plain region (Lubowski et al., 2006). 

The Economic Research Service conducts land- use inventories based on available land- use

data obtained from surveys conducted both by the Economic Research Service and predecessor 

agencies. Figure 4-29 illustrates the dominant land-use patterns in the counties and parishes that 

comprise the BOEM-identified EIAs.

Coastal land loss resulting from erosion, subsidence, sea-level rise, and coastal storms is 

one of the more significant cumulative impacts for land use and coastal infrastructure. The Gulf 

Coast region has been experiencing land loss in varying degrees from state to state, especially in 

coastal Louisiana, which is sinking faster than any place in the world (Marshall, 2013). Figure 4-29

shows the amount of land that coastal Louisiana has lost from 1932 to 2010. Produced for 

Louisiana’s Coastal Master Plan (2012), Figuree 4-30 and 4-31 illustrate scientists’ projections for 

future land loss in Louisiana. The moderate projection (Figure 4-30) assumes more mitigating 

measures, and the less optimistic projection (Figure 4-31) shows the impact if extensive mitigating 

measures are not instituted. Overlaid on all three of these figures are the locations of existing OCS 

oil- and gas-related infrastructure. As evident from these visual depictions, coastal land loss is one 

of the greatest threats to the stability and future of OCS oil- and gas-related infrastructure, producing 

a major negative impact to those facilities located close to areas vulnerable to land loss. The 

severe threat to coastal infrastructure and communities becomes more evident each year, and the 

requests for action continue to increase (Traywick, 2016; Marshall, 2015).

Second only to coastal land loss as a major cumulative impact on land use and coastal 

infrastructure are the regular changes in economic trends on the regional, national, and global 

levels. Micro-economic and macro-economic shifts in demand, investment opportunities, and 

commodity prices all affect the course of business in the oil and gas industry and the regional 

economies and communities in ways that are not always in tandem. For example, the drop in the 

price of oil from the end of 2014 through 2015 kept the price of gas down, which is good for people 

and businesses that require cars and trucks to travel. However, the downturn has also led to 

increasing layoffs in the oil and gas industry (Larino, 2015; Stickney, 2015; Strauss, 2015; 

Thompson, 2016). Despite a rise in oil prices in early 2016, bankruptcies increased for oil 

companies (Eaton, 2016). By mid-2016, with the number layoffs totalling over 350,000, oil 

companies were predicted to be facing a shortage of skilled workers when oil prices rebound 

(Cunninham, 2016). An economic Gordian knot best explains the complex relationship between the 

industry, society at large, and the resources of land use and coastal infrastructure, which reside at 

the core of this intricate system of effects and counter-effects.
Description of the Affected Environment and Impact Analysis 4-435

Figure 4-29. Historical Land Loss in Louisiana, 1932-2010.

Figure 4-30. Moderate Scenario: Projected Land Loss in Louisiana.
4-436 Gulf of Mexico Multisale EIS

Figure 4-31. Less Optimistic Scenario: Projected Land Loss in Louisiana.

Cumulative impacts resulting from all past, present, and reasonably foreseeable future 

non-OCS oil- and-gas related activities could range from beneficial to major depending on the 

specifics of each situation, whether the impacts are measurable, how long the impacts would last, 

and the size of the affected geographic area.

4.14.1.2.4 Incomplete or Unavailable Information

BOEM has identified incomplete information regarding the potential impacts of coastal land 

loss on land use and coastal infrastructure. This incomplete information may be relevant to adverse 

impacts because it is not completely known how current subsidence and erosion is affecting industry 

or what plans industry is making to mitigate current or future impacts. Because there are hundreds 

of large and small property-owning businesses spread across the coastal zone, which directly and 

indirectly support the offshore petroleum industry, the identity of these properties and the 

possibilities of losses due to subsidence, sea-level rise and erosion cannot be quantified at this time. 

BOEM has employed reasonably accepted scientific methodologies to extrapolate from existing 

information on dredged material and other approaches used to mitigate for land loss in completing 

its analysis and formulating the conclusions presented here. For a more detailed discussion on 

deltaic land loss, refer to Chapter 4.3.2 (Coastal Barrier Beaches and Associated Dunes). In the 

case of coastal ports, for example, dredged material from navigation slips are used to fill in property 

and mitigation habitat areas for wildlife and to act as a barrier to protect ports from storm surges 

(Volz, 2013). This example shows that, although BOEM does not possess a complete 
Description of the Affected Environment and Impact Analysis 4-437

understanding of what industrial infrastructure improvements may occur, such as mitigation for land 

loss, industry would most likely mitigate as necessary to protect existing and growing infrastructure. 

With each passing year, the pressure increases to take action and protect critical oil and gas 

infrastructure (Traywick, 2016). Like any industrial infrastructure improvements, future adaptations 

would occur on an as-needed basis or as new technologies become available. While coastal 

infrastructure is subject to the impacts of coastal land loss and routine tropical storm activity, there is 

still considerable motivation to protect existing infrastructure. Therefore, BOEM has determined that 

the information is not essential to a reasoned choice among alternatives. BOEM continues to 

monitor industry and its infrastructure footprint over time to document short- and long-term impacts 

of continued land loss.

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

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

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

companies. Land use in the Gulf Coast analysis region covers a broad spectrum from rural to 

metropolitan land uses, ranging across 133 counties and parishes from the southern tip of Texas 

north along the Texas coastal plain and looping around the Gulf Coast through Louisiana, 

Mississippi, Alabama, and Florida, all the way southward to Key West in Monroe County, Florida. 

For routine operations, impacts would vary across the range of measures from negligible to 

moderate because land use in the region has adjusted to the presence of the oil and gas industry 

over many decades, and oil- and gas-related coastal infrastructure is a mature and extensive 

system, resulting from long-term industry trends, and it is not subject to rapid fluctuations. For 

example, a small-scale expansion of a gas-processing plant would be a negligible impact because 

of the small size of the project, the temporary disruptions caused by increased construction traffic, 

and the geographically small area affected. If the expansion project was larger, lasting a few weeks 

and affecting a larger geographic area, then the impact would be minor. If the gas-processing plant 

project was larger in scale, causing disruptions because of construction activities that last up to 

1 year, then the impact would be moderate. Activities related to a proposed action are expected to 

minimally affect the current land use of the analysis area because most subareas have strong 

industrial bases and designated industrial parks with existing infrastructure and facilities that have 

sufficient capacity to accommodate future growth. BOEM’s scenario projections call for the new 

construction of 0-1 new gas processing facility and 0-1 new pipeline landfall to result from a 

proposed lease sale over the analysis period. Increases in demand for services at other facilities 

would be met by current excess capacity or expansions at current facilities (Dismukes, official 

communication, 2015). These activities, along with noncatastrophic accidental events, are 

reasonably foreseeable.

The impacts of reasonably foreseeable accidental events, such as oil spills, chemical and 

drilling fluid spills, vessel collisions, and spill-response activities are expected to be negligible to 

moderate depending on the location, size, and duration of the event. Potential impacts could 

include damages to private and public lands, personal injury, damages to collateral property 

(moveable property such as vehicles and boats), and economic damages from the disruption of 
4-438 Gulf of Mexico Multisale EIS

business. For example, if an oil spill is very small (not measurable) in size, located in a small 

geographic and remote area, and dissipates quickly, its impact would be negligible. If a spill is 

measurable, covers a larger geographic area, and lasts a few days to a month, then its impact would 

be minor. If a spill occurs in a highly populated area, is larger in quantity, and the response and 

cleanup last over a month and up to a year with either waterborne commerce affected and/or land 

transportation affected, then the impact would be moderate. 

Cumulative impacts resulting from all past, present, and reasonably foreseeable future OCS 

oil- and-gas related activities could range from beneficial to moderate, depending on the specifics 

of each situation, whether the impacts are measurable, how long the impacts would last, and the 

size of the affected geographic area. In general, activities relating to the OCS Oil and Gas Program

and State oil and gas production are expected to minimally affect the current land use of the 

analysis area because most subareas have strong industrial bases and designated industrial

parks to accommodate future growth. The incremental contribution of a proposed lease sale to

the cumulative impacts on land use and coastal infrastructure are expected to be minor because 

the impacts of one lease sale are minimal when compared with the combination of all past, present, 

and future lease sales (USDOI BOEM, 2016a). The cumulative impacts of non-OCS oil- and 

gas-related factors on land use and coastal infrastructure could range from beneficial to major

adverse impacts depending on the specific situation, whether the impacts are measurable, how 

impacts are measured, how long they would last, the size of the affected area, and the viewpoints of 

the various people that may be involved.

4.14.1.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Impacts for land use and coastal infrastructure are directly related to the level of OCS 

oil- and gas-related activities in the Gulf of Mexico. Alternative B would result in less OCS oil- and 

gas-related activities than Alternative A because the WPA (approximately 23 million ac) would not be 

available for leasing. Alternative A includes all three planning areas of the GOM (i.e., the WPA, 

CPA, and EPA). Alternative B includes the CPA and EPA, and excludes the WPA. Therefore, 

Alternative B would produce proportionately smaller OCS oil- and gas-related activities than 

Alternative A, and the impacts of Alternative B would be proportionately less than Alternative A and 

greater than Alternative C. Alternative B impacts could range from neglible to moderately negative 

for routine operations and accidental events, and beneficial to major adverse impacts for 

cumulative impacts depending on the specific situation, whether the impacts are measurable, how 

impacts are measured, how long they would last, the size of the affected area, and the viewpoints of 

the various people that may be involved.

4.14.1.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

Impacts for land use and coastal infrastructure are directly related to the level of OCS 

oil- and gas-related activities in the Gulf of Mexico. Alternative C would result in less OCS oil- and 

gas-related activities than Alternative A or B because the CPA and EPA (approximately 48 million 
Description of the Affected Environment and Impact Analysis 4-439

ac) would not be available leasing. Alternative A includes the WPA, CPA, and EPA, and Alternative 

B include the CPA and EPA. In contrast, Alternative C includes only the WPA. Therefore, 

Alternative C would produce proportionately smaller OCS oil- and gas-related activities than 

Alternative A and B. The impacts of Alternative C would be proportionately less than either 

Alternative A or B, but they would also range from neglible to moderate for routine operations and 

accidental events, and beneficial to major adverse impacts in the cumulative analysis depending on 

the specific situation, whether the impacts are measurable, how impacts are measured, how long 

they would last, the size of the affected area, and the viewpoints of the various people that may be 

involved.

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

Impacts for land use and coastal infrastructure are directly related to the level of OCS 

oil- and gas-related activities in the Gulf of Mexico. Alternative D would have minimal impact 

because there are so few available unleased blocks subject to the Topographic Features, Live 

Bottom (Pinnacle Trend), and Blocks South of Baldwin County, Alabama, Stipulations. The 

difference between Alternatives A, B, and C, with and without the exclusionary stipulations, is 

imperceptible for land use and coastal infrastructure. The impacts under Alternative D would not be 

much different and likely not even be measurable when compared with the other alternatives. To the 

extent that Alternative D may possibly generate less OCS oil- and gas-related activities due to the 

reduced number of blocks available for lease, the impacts of Alternative D may be slightly less than 

Alternative A, B or C, but this difference would likely be indiscernible because BOEM cannot 

speculate as to what blocks industry may have bid on if Alternative D was not chosen. Since the 

difference between Alternative D and Alternatives A, B, and C cannot be determined, the impacts 

would still range from neglible to moderate for routine operations and accidental events, and 

beneficial to major adverse impacts in the cumulative analysis depending on the specific situation, 

whether the impacts are measurable, how impacts are measured, how long they would last, the size 

of the affected area, and the viewpoints of the various people that may be involved.

4.14.1.2.9 Alternative E—No Action

Alternative E would result in no lease sale and, thus, no direct impacts as a result of a

proposed lease sale and no incremental contribution of impacts to land use and coastal 

infrastructure beyond a temporary negative economic impact for the oil and gas industry and coastal 

states, such as Louisiana, that are more dependent on oil and gas revenues. Chapter 4.14.2

describes specific economic impacts.

4.14.2 Economic Factors

This chapter discusses the affected environment, routine activities, accidental events, and 

cumulative impacts to economic factors that would arise from the alternatives. Many of the 

economic impacts of the alternatives would be beneficial, and these impacts are stated in terms of 
4-440 Gulf of Mexico Multisale EIS

standard measures of economic activity. The negative impacts are measured in terms of the 

severity, duration, and geographical extent of impacts. Long-term impacts are those lasting more 

than 1 year. Extensive impacts are those that affect numerous economic impact areas. Severe 

impacts cause sizeable impacts to economic activity in levels or relative to the size of an economic 

impact area. The impact-level definitions are listed below.

Impact-Level Definitions

• Beneficial – Positive impacts stated in levels and percentages of employment

(number of jobs), labor income (wages, benefits, and sole-proprietor income), 

and/or value-added (contribution to gross regional product).

• Negligible – Little or no detectable adverse impact.

• Minor – Adverse impacts are detectable but less than severe.

• Moderate – Adverse impacts are severe but are short-term and/or not extensive.

• Major – Adverse impacts are long-term (more than 1 year), extensive, and 

severe.

4.14.2.1 Description of the Affected Environment

Economic factors are factors that explain and quantify the human behaviors that determine 

the positive and negative impacts from the alternatives. The following sections discuss the overall 

economies that could be impacted by the alternatives and provide specific information regarding the 

offshore oil and gas industry.

Economic Impact Areas

Offshore oil and gas activities affect various onshore areas because of the various industries 

involved and because of the complex supply chains for these industries. Many of these impacts 

occur in counties and parishes along the Gulf of Mexico region. BOEM aggregates 133 GOM 

counties and parishes into 23 EIAs based on economic and demographic similarities among 

counties/parishes (Fannin and Varnado, official communication, 2015); Figure 4-29 is a map of 

these EIAs. Much of the analysis below focuses on these EIAs since many of the positive and 

negative impacts of the alternatives would be concentrated in these EIAs. These EIAs also serve as 

consistent units for which to present economic and demographic data.

Economic and Demographic Data

Woods & Poole Economics, Inc. (2016) provides county-level economic and demographic 

data for prior years, as well as forecasts of these data through 2050. Table 4-33 aggregates the 

Woods & Poole data for 2015 by EIA and presents each EIA’s population, employment, gross 

regional product, labor income, median age, male percentage, and race composition. The largest 

EIAs (presented in descending order of gross regional product) are TX-3 (which includes Houston 

and Galveston), FL-5 (which includes Tampa), LA-6 (which includes New Orleans), FL-6, LA-5 
Description of the Affected Environment and Impact Analysis 4-441

(which includes Baton Rouge) and TX-1. The smallest EIAs (presented in ascending order of gross 

regional product) are MS-2, TX-6, AL-2, LA-2, and TX-4. The forecasts from Woods & Poole 

Economics, Inc. (2016) for future years are presented in the cumulative analysis (Chapter 4.14.2.2). 

Kaplan et al. (2011) presents additional economic and demographic data for certain GOM regions 

that are important to the offshore oil and gas industry.

Table 4-33. Economic and Demographic Information for BOEM's Economic Impact Areas in 2015.

Economic Variables Demographic Variables

EIA Population Employment Gross Regional 

Product1 Labor Income Median Age Male % White Black Hispanic Native American Asian 

Texas

TX-1 1,708,427 751,524 47,016,273 26,381,857 32.0 48.9% 7.4% 0.5% 91.1% 0.1% 0.9%

TX-2 759,550 444,670 42,601,774 21,698,404 39.0 50.0% 37.7% 4.9% 55.5% 0.3% 1.7%

TX-3 6,410,474 3,951,656 452,267,859 275,676,978 35.8 49.7% 37.3% 17.2% 37.2% 0.3% 8.0%

TX-4 162,698 60,147 4,238,588 2,096,976 40.0 49.5% 75.6% 8.9% 14.3% 0.4% 0.7%

TX-5 375,116 208,555 19,231,977 11,061,067 36.7 50.8% 53.9% 25.8% 16.9% 0.4% 3.1%

TX-6 50,032 22,204 1,346,951 681,012 41.6 49.9% 74.8% 18.0% 5.9% 0.5% 0.7%

Louisiana

LA-1 204,995 124,347 10,798,391 6,185,263 38.5 48.8% 69.9% 25.0% 3.1% 0.5% 1.4%

LA-2 88,820 40,311 3,652,318 1,938,194 34.0 52.2% 75.0% 14.5% 7.3% 1.3% 1.9%

LA-3 590,283 337,688 32,356,769 16,331,528 36.6 49.2% 68.4% 26.6% 3.3% 0.5% 1.3%

LA-4 363,427 218,383 22,856,912 12,097,141 37.5 49.3% 67.3% 23.3% 4.8% 3.0% 1.6%

LA-5 854,933 536,057 48,085,588 26,632,392 37.2 48.6% 56.6% 37.0% 4.0% 0.3% 2.2%

LA-6 941,496 618,008 56,199,457 32,026,768 36.4 48.4% 46.3% 39.8% 9.8% 0.4% 3.7%

LA-7 424,409 208,711 15,432,610 8,742,974 38.4 48.7% 73.9% 19.8% 4.7% 0.4% 1.2%

Mississippi 

MS-1 443,912 227,999 15,847,063 9,864,828 39.3 49.4% 71.2% 20.7% 5.0% 0.5% 2.5%

MS-2 68,307 22,231 1,138,488 676,391 38.3 52.0% 79.7% 18.0% 1.7% 0.4% 0.3%

Alabama

AL-1 621,342 337,084 22,645,147 13,605,409 40.0 48.1% 66.7% 27.2% 3.4% 0.9% 1.8%

AL-2 114,322 51,063 3,434,323 1,993,558 42.3 49.0% 57.9% 37.4% 1.6% 2.8% 0.4%

Florida

FL-1 921,108 500,868 34,429,364 20,965,492 39.2 50.4% 75.7% 14.1% 6.3% 0.8% 3.2%

FL-2 510,345 273,431 18,122,863 10,995,475 40.4 50.8% 61.8% 29.4% 6.0% 0.5% 2.3%

FL-3 234,152 88,771 5,348,686 3,245,975 41.3 54.3% 70.6% 21.8% 6.3% 0.5% 0.8%

FL-4 1,436,271 609,646 36,373,271 21,964,488 48.4 48.6% 75.5% 11.2% 10.4% 0.3% 2.6%

FL-5 4,173,838 2,261,114 164,280,085 100,732,515 45.4 48.5% 66.9% 11.9% 17.6% 0.3% 3.2%

FL-6 1,509,624 771,147 48,463,312 29,687,008 45.6 49.6% 68.3% 8.0% 21.8% 0.3% 1.6%

EIA = Economic Impact Area. 1 Gross Regional Product and labor income are presented in thousands of dollars.

Source: Woods & Poole Economics, Inc., 2016.
4-442 Gulf of Mexico Multisale EIS

Offshore Oil and Gas Industry

The offshore energy industry in the Gulf of Mexico extracts oil, natural gas, and natural gas 

liquids (NGLs), which are then processed and transported for use in various activities, including 

transportation, electricity generation, space heating, and chemical manufacturing. Extraction of oil, 

natural gas, and natural gas liquids entails spending on various processes, including G&G 

surveying, drilling, platform fabrication, shipbuilding, and various support services. Spending on 

these processes supports businesses further along supply chains and supports spending by 

workers. Quest Offshore Resources, Inc. (2011) provides an overview of the spending impacts of 

the offshore oil and gas industry in the Gulf of Mexico. This report estimates that $26.9 billion in 

capital and operating expenditures supported $29.1 billion in U.S. gross domestic product in 2009. 

Kaiser et al. (2013) provide background information on the drilling and rig construction markets; 

Eastern Research Group, Inc. (2011) provides background information on the oil services contract 

industry; and Priest and Lajaunie (2014) and Austin et al. (2014a) present background information 

on the shipbuilding and fabrication industries.

The offshore energy industry has been adapting to recent declines in energy prices. Lower 

energy prices have caused slowdowns in offshore drilling activities (Beaubouef, 2015) and rig 

construction (Odell, 2015). However, offshore oil and gas production is generally slower to respond 

to changes in energy prices since offshore developments take years to be designed, approved, and

developed. Once a project is producing, it is often most profitable to maintain production as long as 

the revenues received are above the marginal costs of production. Indeed, GOM offshore oil 

production is forecast to increase from an average of 1.5 MMbbl/day in 2015 to 1.9 MMbbl/day in the 

fourth quarter of 2017 (USDOE, Energy Information Administration, 2016e). This production 

increase reflects the contributions of 14 Gulf of Mexico projects that are expected to come online in 

2016 and 2017 (USDOE, Energy Information Administration, 2016f).

Office of Natural Resources Revenue Data

Government revenues are generated from offshore oil and gas activities through bonus bids, 

rental payments, and royalty payments. Bonus bids are received shortly after a lease sale, rental 

payments occur during the nonproducing phase of a lease, and royalties are paid as a percentage of 

oil and gas output from a lease. BOEM’s “Fair Market Value” webpage describes the rental rates, 

royalty rates, and other terms associated with Gulf of Mexico leases (USDOI, BOEM, 2015c). Some 

offshore oil and gas activities are subject to partial or full royalty exemptions. BOEM’s “Royalty 

Relief Information” webpage provides more information regarding BOEM’s royalty relief programs 

(USDOI, BOEM, 2015d). Panels A, B, and C of Table 4-34 presents data regarding sales volumes, 

sales values, and government revenues received from Federal offshore energy activities in the Gulf 

of Mexico (USDOI, Office of Natural Resources Revenue, 2016). Sales volumes of oil and gas were 

generally slightly higher in 2015 than in 2014. However, sales volumes and government revenues 

were generally lower in 2015 than in 2014, in part due to declines in energy prices.
Description of the Affected Environment and Impact Analysis 4-443

Table 4-34. Sales Volumes, Sales Values, and Revenues.

Panel A: Sales Volumes

FY 2009 2010 2011 2012 2013 2014 2015

Gas (royalty) 

(mcf) 3,515,174,881 1,021,163,854 1,408,872,682 1,113,924,864 950,496,444 840,771,649 901,791,829

Gas (nonroyalty) (mcf) 215,256,077 1,035,853,736 323,546,478 228,996,007 249,725,032 225,115,563 243,981,082

NGL (royalty) 

(bbl) 38,833,183 35,291,345 44,366,261 38,612,327 36,930,555 37,108,821 43,547,877

NGL (nonroyalty) (bbl) 2,672,336 14,757,582 9,066,227 6,720,387 7,920,289 10,479,880 13,600,607

Oil (royalty) 

(bbl) 399,610,189 245,817,393 365,315,753 327,838,813 353,301,996 380,094,970 427,893,211

Oil (nonroyalty) (bbl) 44,831,343 351,281,197 154,048,513 136,239,983 99,872,228 100,214,276 117,987,854

Panel B: Sales Values

Fiscal Year 2009 2010 2011 2012 2013 2014 2015

Gas ($) 9,042,095,734 3,635,054,218 6265443988 3,431,037,416 3,389,367,262 3,673,721,931 3,062,140,872

NGL ($) 1,340,935,987 1,683,276,019 2,203,814,139 2,443,746,995 1,345,608,945 1,396,236,694 1,104,727,436

Oil ($) 22,121,036,571 20,398,834,017 34,955,160,900 35,976,794,554 37,471,600,329 38,509,764,522 26,989,786,050

Other ($) 328,166 81,819 62,776 48,488 65,859 46,065 181,361

Total ($) 32,504,396,457 25,717,246,074 43,424,481,803 41,851,627,453 42,206,642,395 43,579,769,211 31,156,835,720

Panel C: Revenues

Fiscal Year 2009 2010 2011 2012 2013 2014 2015

Gas royalties 

($) 1,270,482,533 578,648,176 867,823,949 477,314,371 492,705,927 506,802,521 397,152,833

NGL royalties 

($) 106,141,947 193,526,754 275,894,256 242,173,963 162,496,377 172,755,305 113,431,762

Oil royalties ($) 2,870,533,400 2,848,085,747 4,795,138,594 4,906,719,993 5,123,552,625 5,167,152,076 3,598,649,485

Other royalties 

($) 44,168 -14,192 3,494 4,163 4,466 2,605 10,310

Rents ($) 226,228,376 236,631,251 219,119,868 217,669,757 244,699,154 229,741,396 215,683,828

Bonus ($) 1,181,075,491 979,569,294 36,751,111 663,714,729 2,675,653,773 967,365,328 642,044,899

Other ($) -82,772,915 119,508,488 23,807,036 31,841,893 34,646,396 46,274,075 -36,537,426

Total ($) 5,571,733,000 4,955,955,519 6,218,538,306 6,539,438,869 8,733,758,719 7,090,093,306 4,930,435,692

(1) This table presents the sales volumes, sales values, and revenues received based on offshore oil and gas activities in the Gulf of 

Mexico.

(2) Data in this table refer to the years in which sales occurred (not to the years in which government revenues were received).

Source: USDOI, Office of Natural Resources Revenue, 2016. 

4.14.2.2 Environmental Consequences

The impacts from routine activities and accidental events, and the cumulative impacts to 

economic factors that would arise from projected activities from a single lease sale are analyzed in 

this chapter. While there are some differences in the amount of activities associated with the 

alternatives, many of the impacts associated with the alternatives are similar. Therefore, this 
4-444 Gulf of Mexico Multisale EIS

chapter describes the impacts that are expected to apply to all alternatives, while any deviations 

from these impact conclusions are discussed in Chapters 4.14.2.2.5-4.14.2.2.9. 

For each alternative, the numerical estimates are presented for two scenarios for oil and gas 

development:

(1) Low: A scenario that corresponds to low amounts of offshore oil and gas 

activities, which could arise due to low oil and gas prices or other unfavorable 

economic conditions. This scenario also assumes that oil and gas leasing 

activities would be spread over two lease sales in a given year.

(2) High: A scenario that corresponds to high amounts of offshore oil and gas 

activities, which could arise due to high oil and gas prices or other favorable 

economic conditions. This scenario also assumes that oil and gas leasing 

activities would be spread over two lease sales in a given year.

It is also possible that industry could focus their leasing activities in a particular lease sale for 

unique circumstances rather than activity being spread over two lease sales in a given year. If this 

would occur, the economic impacts would be approximately double the impacts presented here. 

However, this is unlikely to occur, particularly as industry adjusts to the pattern of two lease sales 

per year.

4.14.2.2.1 Routine Activities

Routine activities arising from a proposed action would have various economic impacts. 

First, extraction of oil, NGLs, and natural gas generate expenditures on various goods and services. 

Routine activities could also generate corporate profits and government revenues, as well as have 

impacts on the overall energy market. Finally, a proposed action would have negative impacts 

(discussed below) that would partially offset the positive impacts. It is important to note that a 

proposed action occurs in the context of an expansive existing offshore oil and gas industry. 

Therefore, the various impacts (discussed below) should be interpreted as the extent to which the 

alternatives contribute to the impacts of the existing offshore oil and gas existing industry.

Expenditure Impacts

A proposed action would have economic impacts on a variety of businesses along the OCS 

industry’s supply chain. For example, a proposed action would directly affect firms that drill wells, 

manufacture equipment, construct pipelines, and service OCS oil- and gas-related activities. The 

OCS oil- and gas-related activities would also impact the suppliers to those firms, as well as firms 

that depend on consumer spending of oil and gas industry workers. In order to estimate these 

impacts, BOEM has developed MAG-PLAN, which is a two-stage economic model. The first stage 

estimates the levels of spending in various industries that arise from a particular scenario for oil and 

gas exploration and development. The second stage estimates the employment, income, and value 

added impacts that result from oil and gas industry spending along the Gulf Coast. The OCS 
Description of the Affected Environment and Impact Analysis 4-445

industry’s direct spending would support activities further down the supply chain; these are referred 

to as “indirect” impacts. In addition, the incomes of employees along the OCS industry’s supply 

chain would support consumer spending throughout the economy; these are referred to as “induced” 

impacts. These impacts are estimated using the economic modeling software and data system 

IMPLAN. In particular, MAG-PLAN uses IMPLAN “multipliers” to compute how OCS spending 

translates into various direct, indirect, and induced economic impacts. MAG-PLAN results for the 

various scenarios are presented in Chapters 4.14.2.2.5-4.14.2.2.9. 

Government Revenue Impacts

A proposed action would generate government revenues through bonus bids, rental 

payments, and royalty payments. Revenue forecasts for the alternatives are discussed in Chapters 

4.14.2.2.5-4.14.2.2.9. The impacts generated by these revenues depend on where and how the 

revenues are used. Historically, most revenues have accrued directly to the Federal Treasury. 

Although it is not possible to trace Federal spending to specific revenue streams, it is reasonable to 

assume that Federal OCS revenues would be spent in approximately the same proportions as 

overall Federal spending. This implies that the Federal revenue impacts of OCS oil- and gas-related 

activities would be fairly widespread, and thus not overly concentrated in BOEM’s economic impact 

areas. Historically, modest portions of OCS revenues beyond those implicit in normal Federal 

spending have been allocated to the Gulf Coast States, including 8(g) revenues (which arise due to 

leasing with 3 mi [5 km] of State waters), the Coastal Impact Assistance Program, and Phase 1 

revenue sharing arising from the Gulf of Mexico Energy Security Act of 2006 (GOMESA). Phase 2 

of GOMESA revenue sharing, which will begin in Fiscal Year 2017, will expand revenue sharing with 

Texas, Louisiana, Mississippi, and Alabama. In particular, Phase 2 of GOMESA calls for 

37.5 percent of qualified revenues to be disbursed to the Gulf Coast States and their political 

subdivisions, and 12.5 percent of revenues to be disbursed to the Land and Water Conservation 

Fund. Phase 2 revenue sharing will be subject to a $500 million cap through 2055 (USDOI, BOEM, 

2015d). Phase 2 of GOMESA may increase the beneficial impacts to BOEM’s economic impact 

areas arising from a proposed action, although only if the revenues occur in a year in which the cap 

was not reached by revenues arising from other lease sales. The economic impacts of the various 

revenue disbursements would depend on how and where the money is spent. The OCS oil- and 

gas-related activities can also induce government revenues arising from taxes on economic activities 

(such as taxes on profits and dividends). The USDOI (2015) provides methodologies for estimating 

the scales and distributions of revenue impacts of OCS oil- and gas-related activities. This report 

estimates that revenue impacts accounted for 26 percent of total value-added impacts in the United 

States in 2014. This percentage is forecast to remain roughly similar in future years, although it 

could vary based on oil prices and the geographic distributions of impacts would change because of 

GOMESA revenues.

Profit Impacts

A proposed action could also generate profits to firms along the OCS supply chain. 

Corporate profits can be distributed to stockholders as dividends or retained by firms for future 

spending on goods and services. Higher profits can also increase stock prices, which would 
4-446 Gulf of Mexico Multisale EIS

increase the wealth of stockholders. Since stocks of most energy firms can be held by people from 

anywhere in the world, the wealth and dividend impacts would be fairly widespread and, thus, not 

overly concentrated in BOEM’s economic impact areas. Similarly, it is difficult to trace specific 

spending by firms to increases in corporate profits, although these impacts are also likely to be 

widespread. The USDOI (2015) estimates that approximately 25 percent of total value-added 

benefit to the United States from the OCS Program arises due to corporate profits, and this 

percentage could vary slightly during the timeframe of a proposed action, given changes in oil prices 

and other factors.

Market Impacts

The oil, natural gas, and NGLs produced due to a proposed action would meet the demands 

of end users of those products. Increased energy supply would put downward pressure on energy 

prices, although the small scale of a proposed action relative to the overall energy market would 

make these price effects minimal. The OCS crude oil production typically has different quality 

measures (such as API gravity and sulfur content) than crude oil from other sources and flows 

through pipelines already in place, which can enhance the relative value of OCS crude to nearby 

refiners designed to process OCS-type crude oil. A proposed action can also contribute to U.S. 

policy goals of energy independence and security. Again, these impacts would be small due to the 

small scale of a proposed action. 

Adverse Impacts

A proposed action could negatively affect various resources, as described in the other 

chapters of this Multisale EIS. The corresponding negative economic impacts are also discussed in 

their respective chapters. For example, the OCS Program could cause negative impacts to 

recreational fishing, commercial fisheries, recreational resources, land use and coastal 

infrastructure, and social factors. Industrial Economics, Inc., et al. (2015) provides information 

regarding the Offshore Environmental Cost Model, which incorporates methodologies for quantifying 

the adverse impacts to various resources. However, these adverse impacts are likely to be minor

because of the small scale of a proposed action.

In summary, a proposed action would have various beneficial impacts, such as impacts from 

expenditures, government revenues, corporate profits, and market adjustments. A proposed action 

would also lead to minor adverse impacts that would partially offset the beneficial impacts.

4.14.2.2.2 Accidental Events

Accidental events, such as oil spills, chemical spills, and vessel collisions, can have various 

impacts on local economies. The most direct impacts are felt in industries that depend on resources 

that are damaged or rendered unusable for a period of time. For example, beach recreation, 

recreational fishing, and commercial fishing would be vulnerable if beach or fish resources were 

damaged due to an accidental event. However, since accidental events arising from a proposed 

action would likely be small, the impacts to economic factors would likely be negligible or minor. 
Description of the Affected Environment and Impact Analysis 4-447

More information on the impacts of accidental events on these individual resources can be found in 

Chapters 4.10-4.12. An oil spill could also impact important transportation routes or impact the 

operations of port facilities. However, the likelihood of a single oil spill shutting down an entire 

waterway or port facility is quite low.

The other economic impacts of an accidental event would be determined by indirect actions 

or events that occur along with an oil spill. For example, an oil spill could lead to decreased levels of 

oil and gas industry operations. These impacts would be most felt in coastal Louisiana and Texas 

since these are the primary locations where OCS oil- and gas-related employment is concentrated. 

The direct impacts of an oil spill on a particular industry would also ripple through that industry’s 

supply chain; consumer spending by employees of these firms would also have impacts to the 

broader economy. Decreased levels of offshore oil and gas activities could also impact corporate 

profits and the revenue streams of the various levels of government in the impacted areas. Finally, 

the response and cleanup operations following an oil spill can have impacts on local economies. For 

example, compensation for damages could partially mitigate the economic impacts of an accidental 

event. The influx of response workers to local areas can have positive economic impacts, although 

it can also cause disruptions to the normal functioning of local economies. In addition, the people 

and equipment that are dedicated to oil-spill response efforts may be diverted from some existing 

services (such as hospitals, firefighting capability, and emergency services) available to local 

residents. These indirect impacts would be negligible for most spills expected to arise from a 

proposed action, although they could be minor in unique circumstances.

The Deepwater Horizon oil spill provides some insights into the impacts of oil spills, although 

an oil spill of the scale of the Deepwater Horizon is not part of a proposed action and not reasonably 

foreseeable; the impacts of catastrophic spills are discussed in Catastrophic Spill Event Analysis

white paper (USDOI, BOEM, 2017). Austin et al. (2014b and 2014c) are two volumes of a recently 

completed study of the economic and social impacts of the Deepwater Horizon oil spill. This study 

employed an ethnographic methodology that entailed analyzing data sources, examining various 

sources of descriptive information, and conducting field interviews with people in Louisiana, 

Mississippi, and Alabama. This study documents the complex and varied impacts of the Deepwater 

Horizon oil spill during the 20 months subsequent to the spill. This study found that the impacts of 

the spill on a particular community depended on a number of factors, such as its proximity to the 

spill, its economic structure, its social and political dynamics, its organizational structure for dealing 

with disasters, and its ability to adapt to the structures of the oil cleanup and damage claims 

processes.

Overall, the economic impacts from accidental events likely to arise from a proposed action 

would likely be negligible or minor because any oil spills would likely be small.

4.14.2.2.3 Cumulative Impacts

A proposed action will occur in the context of numerous cumulative impacts to economic 

factors. This chapter analyzes these factors in various economic impact areas along the Gulf Coast. 
4-448 Gulf of Mexico Multisale EIS

The timeframe for the analysis is the life cycle of offshore oil and gas activities likely to arise from a 

proposed action; most of these activities will occur within approximately 50 years. This chapter first 

analyzes the impacts of the overall OCS Program, which refers to all past, present, and future lease 

sales (refer to Chapter 3.3.1 for more information). This chapter then presents data from Woods 

and Poole Economics Inc. (2016), which provides forecasts of various economic variables over time. 

Finally, this chapter analyzes the cumulative impacts to the overall energy market.

OCS Oil- and Gas-Related Impacts

A proposed action would contribute to the economic impacts arising from the overall OCS 

Program. The OCS Program would have economic impacts on a variety of firms along the OCS 

industry’s supply chain. BOEM uses the model MAG-PLAN (described above) to estimate the 

impacts of offshore oil and gas industry expenditures. MAG-PLAN’s estimates of the total 

employment, labor income, and value-added impacts for the low and high cumulative scenarios are 

presented in Tables 4-35 and 4-36. These tables present the average values (over 50 years), peak 

values, and percent of peak values relative to total employment, labor income, and value-added in 

each EIA. In the low scenario, the OCS Program would support a peak of 110,000 jobs, $8 billion in 

labor income, and $14 billion in value-added benefits throughout the United States. Most of these 

impacts would occur in the Gulf of Mexico region, particularly in coastal Texas and Louisiana. The 

EIAs that would experience the highest economic impacts are TX-3, TX-2, LA-3, LA-4, LA-6, MS-1, 

and AL-1. In the high scenario, a proposed action would support a peak of 250,000 jobs, $15 billion 

in labor income, and $24 billion in value-added. The geographic distributions of impacts would be 

similar to those of the low scenario.

The overall OCS Program generates government revenues through bonus bids, rental 

payments, and royalty payments (described above). BOEM estimates the revenues associated with 

the OCS Program under the low- and high-case cumulative scenarios for the following time horizons: 

bonus bids (26 years); rental payments (35 years); and royalty payments (70 years). In the low-case 

scenario, the OCS Program would generate approximately $9.4 billion in bonus bids, $2.6 billion in 

total rental payments (with an annual peak of $151 million), and $132 billion in royalty payments 

(with an annual peak of $3.5 billion). In the high-case scenario, the OCS Program would generate 

approximately $17.8 billion in bonus bids, $4.8 billion in total rental payments (with an annual peak 

of $175 million), and $922.9 billion in total royalty payments (with an annual peak of $18.8 billion). 

The geographic distributions of impacts from these revenues would correspond to those described 

above.

A proposed action would also contribute to the corporate profit impacts, market impacts, 

adverse impacts from routine activities, and adverse impacts from accidental events that would arise 

from the overall OCS Program. The impacts arising from the overall OCS Program would be directly

proportional to the amount of activity (discussed above). The incremental contribution of any of the 

alternatives relative to the overall OCS Program would be beneficial to minor. 
Description of the Affected Environment and Impact Analysis 4-449

Table 4-35. Cumulative Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak % 

Texas

TX-1 1,340 2,470 0.0% 67,000 127,000 0.0% 101,000 190,000 0.0%

TX-2 3,360 6,310 0.1% 204,000 378,000 0.1% 378,000 679,000 0.0%

TX-3 13,890 26,150 0.1% 1,276,000 2,437,000 0.1% 2,433,000 4,343,000 0.0%

TX-4 100 190 0.0% 6,000 12,000 0.0% 13,000 23,000 0.0%

TX-5 370 670 0.0% 27,000 48,000 0.0% 76,000 122,000 0.0%

TX-6 20 30 0.0% 1,000 2,000 0.0% 2,000 3,000 0.0%

All Texas EIAs 19,080 35,830 – 1,582,000 3,002,000 – 3,002,000 5,360,000 –

Rest of Texas 2,920 5,700 – 204,000 409,000 – 401,000 741,000 –

Texas Total 22,000 41,530 – 1,786,000 3,411,000 – 3,404,000 6,098,000 –

Louisiana

LA-1 1,040 1,970 0.2% 74,000 141,000 0.2% 111,000 210,000 0.2%

LA-2 40 80 0.0% 2,000 3,000 0.0% 3,000 6,000 0.0%

LA-3 2,810 5,150 0.2% 147,000 266,000 0.1% 277,000 485,000 0.1%

LA-4 3,560 6,850 0.3% 247,000 476,000 0.3% 400,000 752,000 0.2%

LA-5 1,100 2,190 0.1% 57,000 115,000 0.0% 94,000 183,000 0.0%

LA-6 3,290 6,380 0.1% 198,000 383,000 0.1% 308,000 579,000 0.1%

LA-7 510 1,000 0.1% 26,000 51,000 0.0% 44,000 83,000 0.0%

All Louisiana EIAs 12,350 23,510 – 751,000 1,428,000 – 1,238,000 2,293,000 –

Rest of Louisiana 1,850 3,570 – 105,000 206,000 – 212,000 393,000 –

Louisiana Total 14,200 27,060 – 856,000 1,634,000 – 1,450,000 2,681,000 –

Mississippi

MS-1 2,460 5,000 0.3% 129,000 264,000 0.3% 195,000 392,000 0.3%

MS-2 120 240 0.2% 4,000 8,000 0.1% 7,000 14,000 0.1%

All Mississippi EIAs 2,580 5,230 – 133,000 272,000 – 202,000 406,000 –

Rest of Mississippi 2,240 4,350 – 120,000 237,000 – 223,000 413,000 –

Mississippi Total 4,820 9,590 – 252,000 509,000 – 425,000 819,000 –

Alabama

AL-1 2,810 5,900 0.2% 135,000 294,000 0.2% 227,000 473,000 0.2%

AL-2 220 450 0.1% 9,000 20,000 0.1% 18,000 35,000 0.1%

All Alabama EIAs 3,020 6,350 – 144,000 314,000 – 244,000 508,000 –

Rest of Alabama 1,760 3,540 – 104,000 218,000 – 205,000 386,000 –

Alabama Total 4,780 9,890 – 248,000 532,000 – 450,000 892,000 –

Florida

FL-1 290 680 0.0% 21,000 53,000 0.0% 40,000 90,000 0.0%

FL-2 10 20 0.0% 0 1,000 0.0% 1,000 2,000 0.0%

FL-3 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-4 50 110 0.0% 3,000 7,000 0.0% 7,000 14,000 0.0%

FL-5 20 50 0.0% 1,000 3,000 0.0% 3,000 5,000 0.0%

FL-6 0 10 0.0% 0 1,000 0.0% 1,000 1,000 0.0%

All Florida EIAs 380 870 – 26,000 64,000 – 52,000 112,000 –

Rest of Florida 1,700 3,310 – 107,000 209,000 – 202,000 370,000 –

Florida Total 2,080 4,180 – 132,000 273,000 – 254,000 477,000 –
4-450 Gulf of Mexico Multisale EIS

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

All States

All EIAs in All States 37,410 71,780 – 2,635,000 5,080,000 – 4,738,000 8,675,000 –

All Gulf States 47,880 92,250 – 3,275,000 6,359,000 – 5,981,000 10,966,000 –

USA

Rest of the United 

States 9,520 20,750 – 726,000 1,650,000 – 1,540,000 3,020,000 – 

Totals

Total Expenditure 

Impacts 57,400 113,000 – 4,000,000 8,009,000 – 7,521,000 13,986,000 – 

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Table 4-36. Cumulative High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak% Average Peak Peak %

Texas

TX-1 2,306 4,118 0.22% 100,196 176,513 0.21% 152,521 268,012 0.18%

TX-2 7,726 13,158 1.62% 404,130 680,193 1.41% 589,364 994,267 1.05%

TX-3 33,440 57,743 0.63% 2,686,295 4,632,169 0.58% 3,983,622 7,002,487 0.53%

TX-4 271 441 0.36% 12,588 20,326 0.40% 22,203 36,656 0.37%

TX-5 994 1,608 0.45% 56,000 89,409 0.40% 90,764 145,189 0.37%

TX-6 29 56 0.12% 1,204 2,283 0.14% 2,268 4,302 0.13%

All Texas EIAs 44,766 76,881 -- 3,260,413 5,589,107 -- 4,840,743 8,432,100 --

The Rest of Texas 7,727 13,498 -- 458,444 804,237 -- 776,308 1,370,875 --

Texas Total 52,494 90,345 -- 3,718,857 6,391,779 -- 5,617,051 9,799,894 --

Louisiana

LA-1 2,940 4,808 2.20% 205,225 334,157 2.70% 306,816 498,169 2.12%

LA-2 108 202 0.26% 3,831 7,226 0.15% 6,918 12,834 0.14%

LA-3 8,670 14,011 2.03% 430,130 697,030 1.67% 655,326 1,072,934 1.22%

LA-4 9,654 15,937 3.69% 624,946 1,032,521 3.62% 908,227 1,505,238 2.57%

LA-5 2,705 5,006 0.46% 134,179 250,781 0.40% 207,449 382,517 0.32%

LA-6 8,864 14,708 1.39% 512,714 858,553 1.29% 732,900 1,214,249 0.98%

LA-7 1,378 2,368 0.54% 64,817 112,603 0.49% 97,603 166,951 0.40%

All Louisiana EIAs 34,318 56,867 -- 1,975,841 3,279,621 -- 2,915,240 4,846,603 --

The Rest of Louisiana 4,778 8,528 -- 223,072 396,800 -- 407,120 735,751 --

Louisiana Total 39,096 65,329 -- 2,198,913 3,673,893 -- 3,322,359 5,577,182 --

Mississippi

MS-1 5,678 10,844 2.62% 281,225 536,817 2.47% 414,605 786,002 2.64%

MS-2 271 501 1.26% 9,030 16,948 1.15% 15,118 27,908 1.14%

All Mississippi 

EIAs 5,949 11,344 -- 290,255 553,732 -- 429,722 813,822 --

Rest of 

Mississippi 5,400 9,621 -- 244,382 434,227 -- 416,953 747,048 --

Mississippi Total 11,349 20,909 -- 534,637 987,681 -- 846,676 1,559,280 --
Description of the Affected Environment and Impact Analysis 4-451

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak% Average Peak Peak %

Alabama

AL-1 6,546 12,355 1.78% 296,500 563,585 1.72% 486,940 917,481 1.67%

AL-2 515 995 1.08% 19,949 38,513 0.89% 36,919 69,866 0.93%

All Alabama EIAs 7,061 13,347 -- 316,449 602,034 -- 523,859 987,207 --

The Rest of Alabama 4,478 7,839 -- 222,550 389,239 -- 396,062 699,634 --

Alabama Total 11,538 21,178 -- 538,999 990,618 -- 919,921 1,684,485 --

Florida

FL-1 615 1,173 0.12% 37,176 72,941 0.14% 64,156 126,359 0.15%

FL-2 29 50 0.01% 1,085 1,870 0.01% 2,102 3,625 0.01%

FL-3 9 15 0.01% 321 526 0.01% 693 1,135 0.01%

FL-4 131 227 0.02% 5,876 10,302 0.02% 12,623 22,243 0.02%

FL-5 55 101 0.00% 2,816 5,136 0.00% 5,031 9,213 0.00%

FL-6 11 21 0.00% 465 863 0.00% 907 1,684 0.00%

All Florida EIAs 850 1,570 -- 47,739 90,836 -- 85,511 162,773 --

The Rest of Florida 4,385 7,682 -- 239,657 411,534 -- 400,325 702,037 --

Florida Total 5,235 9,127 -- 287,395 494,655 -- 485,836 851,705 --

All States

All EIAs in all States 92,944 159,204 -- 5,890,697 10,063,551 -- 8,795,075 15,163,286 --

All Gulf States 119,712 206,197 -- 7,278,803 12,491,355 -- 11,191,843 19,398,421 --

USA

The Rest of the United 

States 22,910 41,377 -- 1,445,637 2,613,265 -- 2,740,228 4,958,974 --

Totals

Total Expenditure 

Impacts 142,622 246,535 -- 8,724,440 15,022,129 -- 13,932,071 24,217,942 --

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Non-OCS Oil- and Gas-Related Impacts

Woods & Poole Data

Most approaches to analyzing cumulative impacts begin by assembling a list of other likely 

projects and actions that would be included with a proposed action for analysis. However, no such 

list of future projects and actions could be assembled that would be sufficiently current and 

comprehensive to support a cumulative analysis for all 133 of the coastal counties and parishes in 

the analysis area. Instead of an assemblage of future possible projects and actions, the analysis 

employs the economic and demographic projections from Woods & Poole Economics, Inc. (2016) to 

define the contributions of other likely projects, actions, and trends to the cumulative case. These 

projections are based on local, regional, and national data, as well as likely changes to economic 

and demographic conditions. Therefore, the projections include employment associated with the 

continuation of current patterns in OCS leasing activity, as well as the continuation of trends in other 

industries important to the region.
4-452 Gulf of Mexico Multisale EIS

Woods & Poole Economics, Inc. (2016) provides county-level economic and demographic 

data for prior years, as well as forecasts of these data through 2050. Table 4-37 aggregates Woods 

& Poole’s forecasts for 2050 data by EIA and presents each EIA’s population, employment, gross 

regional product, labor income, median age, male percentage, and race composition. The largest 

EIAs (presented in descending order of gross regional product) will be TX-3 (which includes Houston 

and Galveston), FL-5 (which includes Tampa), TX-1, FL-6, LA-5 (which includes Baton Rouge), and 

LA-6 (which includes New Orleans). The smallest EIAs (presented in ascending order of gross 

regional product) will be MS-2, TX-6, LA-2, AL-2, and TX-4. From 2015 through 2050, the fastest 

employment growth is forecast in TX-1, TX-3, FL-4, and FL-6; the slowest employment growth is 

forecast in AL-2, LA-6, TX-5, and MS-1.

Table 4-37. Economic and Demographic Information for BOEM's Economic Impact Areas in 2050.

Economic Variables Demographic Variables

EIA Population Employment

Gross 

Regional 

Product1

Labor 

Income

Median 

Age

Male 

% White Black Hispanic Native 

American Asian 

Texas

TX-1 3,413,196 1,655,646 139,857,198 78,299,743 37.1 49.5% 4.0% 0.5% 94.7% 0.0% 0.8%

TX-2 905,689 617,988 80,514,803 39,928,606 39.3 50.9% 26.2% 6.3% 64.6% 0.3% 2.6%

TX-3 11,596,749 7,606,527 1,167,893,945 701,659,782 37.8 50.0% 19.3% 14.4% 52.8% 0.2% 13.3%

TX-4 235,465 94,451 7,944,813 4,196,779 41.3 49.9% 61.8% 10.0% 26.4% 0.5% 1.3%

TX-5 415,258 271,986 32,211,686 18,640,535 40.3 53.2% 33.5% 23.1% 39.4% 0.4% 3.6%

TX-6 61,514 32,302 2,364,967 1,212,871 41.3 49.8% 53.6% 28.9% 15.4% 0.6% 1.6%

Louisiana

LA-1 241,847 168,746 18,859,676 10,353,944 40.7 48.7% 65.0% 26.8% 5.1% 0.6% 2.5%

LA-2 106,352 54,764 4,945,241 3,450,122 35.9 51.6% 68.1% 15.8% 11.9% 1.5% 2.7%

LA-3 761,793 528,239 67,655,760 34,171,286 40.2 49.5% 62.2% 30.5% 5.1% 0.5% 1.6%

LA-4 423,021 318,703 41,787,836 22,427,117 41.5 49.5% 55.9% 26.0% 11.5% 3.5% 3.1%

LA-5 1,256,552 858,192 95,400,731 52,218,596 42.7 49.1% 49.3% 41.3% 6.0% 0.3% 3.1%

LA-6 939,494 756,729 89,523,947 50,440,660 39.5 49.1% 33.1% 41.9% 19.3% 0.4% 5.3%

LA-7 632,032 326,712 31,467,065 17,856,535 41.4 48.5% 64.7% 23.2% 9.6% 0.4% 2.0%

Mississippi 

MS-1 529,598 306,309 25,016,905 16,560,907 41.2 49.2% 62.7% 24.7% 9.3% 0.4% 2.9%

MS-2 89,691 30,831 2,110,264 1,166,865 41.1 52.9% 72.3% 24.5% 2.5% 0.4% 0.4%

Alabama

AL-1 857,412 524,594 44,241,201 26,059,807 42.0 47.9% 61.7% 28.5% 6.3% 0.8% 2.7%

AL-2 114,035 61,199 5,460,995 2,974,101 46.3 50.5% 45.4% 46.5% 2.9% 4.2% 0.9%
Description of the Affected Environment and Impact Analysis 4-453

Economic Variables Demographic Variables

EIA Population Employment

Gross 

Regional 

Product1

Labor 

Income

Median 

Age

Male 

% White Black Hispanic Native 

American Asian 

Florida

FL-1 1,320,671 790,574 65,277,669 41,474,136 42.7 52.1% 69.1% 16.9% 9.4% 0.6% 4.1%

FL-2 708,344 410,243 34,132,024 20,466,253 45.4 52.3% 53.2% 37.4% 6.1% 0.4% 2.9%

FL-3 328,245 132,454 10,349,100 6,060,294 43.9 56.5% 64.0% 26.4% 8.0% 0.4% 1.2%

FL-4 2,471,050 1,096,519 81,928,758 50,486,375 52.0 50.4% 69.4% 12.6% 14.6% 0.3% 3.1%

FL-5 6,261,022 3,686,743 348,669,486 221,877,815 45.1 49.5% 45.5% 14.1% 33.8% 0.2% 6.4%

FL-6 2,522,878 1,385,733 121,178,379 73,076,081 47.2 50.9% 51.1% 7.5% 39.7% 0.2% 1.5%

EIA = Economic Impact Area.

1 Gross Regional Product is presented in thousands of dollars.

Source: Woods & Poole Economics, Inc., 2016 (CEDDS data).

Overall Energy Market

The oil and gas industry will be impacted by the various forces affecting supply and demand 

for energy products. For example, the rapid expansion of U.S. onshore energy production in recent 

years contributed to a noticeable decline in oil prices beginning in late 2014. Energy supply and 

demand has also been affected by international developments, including policy towards Iran and 

decisions made by the Organization for Petroleum Exporting Countries (International Energy 

Agency, 2016). Demand for energy products will also be affected by various factors, including 

economic activity, technological developments, and government policies. The Energy Information 

Administration provides forecasts of energy markets that incorporate these various factors. In 

particular, the Energy Information Administration publishes monthly short-term (2-year) forecasts 

(USDOE, Energy Information Administration, 2016e) and annual long-term (25-year) forecasts 

(USDOE, Energy Information Administration, 2016d). The incremental contribution of a proposed 

action relative to the outlooks described in these reports is expected to be minimal.

4.14.2.2.4 Incomplete or Unavailable Information

Even after evaluating the information above, there is still incomplete or unavailable 

information. This information primarily relates to the onshore geographic distributions of economic 

impacts arising from the OCS Program, which would allow BOEM to better estimate the impacts 

from routine activities and cumulative impacts. This information is difficult to obtain since most data 

sources do not adequately differentiate between onshore and offshore oil and gas activities. In 

addition, standard data sources do not trace revenue and corporate profit streams to ultimate 

expenditures. BOEM used reasonably accepted scientific methodologies to extrapolate from 

existing information in completing the relevant analysis and formulating the conclusions presented 

here. For example, BOEM used the model MAG-PLAN to estimate the impacts of the alternatives 

and OCS Program. In addition, the economic impacts arising from the OCS Program are generally 

positive, not adverse. Therefore, BOEM has determined that the incomplete or unavailable 

information, while relevant, is not essential to a reasoned choice among alternatives.
4-454 Gulf of Mexico Multisale EIS

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

The impacts of Alternative A would correspond to the impacts discussed above. This 

chapter describes the numerical impact estimates for Alternative A. The MAG-PLAN’s estimates of 

the total employment, labor income, and value-added expenditure impacts for the low and high 

scenarios are presented in Tables 4-38 and 4-39. These tables present the average values (over 

50 years), peak values, and percent of peak values relative to total employment, labor income, and 

value-added in each EIA. The average values are calculated over 50 years for consistency and 

because that is the time horizon over which activities arising from the alternatives are expected to 

occur. In the low scenario, a proposed action would support a peak of 9,500 jobs, $600 million in 

labor income, and $970 million in value-added benefits throughout the United States. Most of these 

impacts would occur in the Gulf of Mexico region, particularly in coastal Texas and Louisiana. The 

EIAs that would experience the highest economic impacts are TX-3, TX-2, LA-3, LA-4, LA-6, MS-1, 

and AL-1. However, these impacts would represent a small fraction of each EIA’s economy. In the 

high scenario, a proposed action would support a peak of 27,000 jobs, $1,7 billion in labor income, 

and $2.6 billion in value-added. The geographic distributions of impacts would be similar to those of 

the low scenario. However, these expenditure impacts would represent less than 1 percent of the 

economies of all EIAs. The impacts of the very high scenario would be double the impacts of the 

high scenario. However, as discussed previously, the very high scenario is unlikely to occur.

Table 4-38. Gulf of Mexico Single Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak % 

Texas

TX-1 20 220 0.0% 1,000 9,000 0.0% 1,000 13,000 0.0%

TX-2 60 610 0.1% 3,000 30,000 0.1% 4,000 44,000 0.0%

TX-3 250 1,900 0.1% 20,000 150,000 0.1% 31,000 241,000 0.0%

TX-4 0 20 0.0% 0 1,000 0.0% 0 2,000 0.0%

TX-5 10 50 0.0% 0 3,000 0.0% 1,000 5,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 340 2,660 – 25,000 185,000 – 38,000 294,000 –

Rest of Texas 70 460 – 4,000 29,000 – 7,000 51,000 –

Texas Total 410 3,120 – 28,000 213,000 – 45,000 345,000 –

Louisiana

LA-1 20 170 0.2% 2,000 12,000 0.2% 2,000 17,000 0.2%

LA-2 0 10 0.0% 0 0 0.0% 0 0 0.0%

LA-3 50 340 0.2% 3,000 16,000 0.1% 4,000 26,000 0.1%

LA-4 70 600 0.3% 5,000 40,000 0.3% 7,000 57,000 0.2%

LA-5 20 200 0.1% 1,000 10,000 0.0% 2,000 16,000 0.0%

LA-6 60 500 0.1% 4,000 30,000 0.1% 5,000 42,000 0.1%

LA-7 10 80 0.1% 1,000 4,000 0.0% 1,000 6,000 0.0%

All Louisiana EIAs 250 1,870 – 14,000 113,000 – 21,000 163,000 –

Rest of Louisiana 40 300 – 2,000 14,000 – 4,000 28,000 –

Louisiana Total 290 2,150 – 16,000 126,000 – 25,000 190,000 –
Description of the Affected Environment and Impact Analysis 4-455

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Mississippi

MS-1 50 470 0.3% 3,000 24,000 0.3% 4,000 35,000 0.3%

MS-2 0 20 0.2% 0 1,000 0.1% 0 1,000 0.1%

All Mississippi EIAs 60 490 – 3,000 25,000 – 4,000 36,000 –

Rest of Mississippi 50 350 – 2,000 16,000 – 4,000 29,000 –

Mississippi Total 100 830 – 5,000 41,000 – 8,000 64,000 –

Alabama

AL-1 60 600 0.2% 3,000 28,000 0.2% 5,000 47,000 0.2%

AL-2 10 40 0.1% 0 2,000 0.1% 0 3,000 0.1%

All Alabama EIAs 70 640 – 3,000 30,000 – 5,000 51,000 –

Rest of Alabama 40 310 – 2,000 16,000 – 4,000 30,000 –

Alabama Total 110 940 – 5,000 45,000 – 9,000 80,000 –

Florida

FL-1 10 90 0.0% 0 6,000 0.0% 1,000 11,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 1,000 0.0% 0 1,000 0.0%

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 10 100 – 1,000 7,000 – 1,000 12,000 –

Rest of Florida 40 290 – 2,000 14,000 – 4,000 27,000 –

Florida Total 50 380 – 3,000 20,000 – 5,000 37,000 –

All States

All EIAs in All States 720 5,730 – 45,000 358,000 – 69,000 550,000 –

All Gulf States 960 7,420 – 58,000 445,000 – 91,000 713,000 –

USA

Rest of the United 

States 220 2,150 – 14,000 136,000 – 27,000 262,000 – 

Totals

Total Expenditure 

Impacts 1,180 9,540 – 72,000 579,000 – 118,000 970,000 – 

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.
4-456 Gulf of Mexico Multisale EIS

Table 4-39. Gulf of Mexico Single High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak % 

Texas

TX-1 90 480 0.0% 4,000 20,000 0.0% 6,000 29,000 0.0%

TX-2 320 1,310 0.1% 17,000 66,000 0.1% 24,000 95,000 0.0%

TX-3 2,170 7,640 0.1% 178,000 617,000 0.1% 246,000 865,000 0.0%

TX-4 10 40 0.0% 1,000 2,000 0.0% 1,000 3,000 0.0%

TX-5 40 140 0.0% 2,000 8,000 0.0% 3,000 12,000 0.0%

TX-6 0 10 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 2,630 9,490 – 201,000 705,000 – 281,000 997,000 –

Rest of Texas 360 1,200 – 22,000 73,000 – 37,000 126,000 –

Texas Total 2,990 10,650 – 223,000 778,000 – 318,000 1,122,000 –

Louisiana

LA-1 160 430 0.2% 11,000 30,000 0.2% 16,000 43,000 0.2%

LA-2 10 20 0.0% 0 1,000 0.0% 0 1,000 0.0%

LA-3 460 1,240 0.2% 23,000 61,000 0.1% 34,000 92,000 0.1%

LA-4 480 1,460 0.3% 31,000 95,000 0.3% 45,000 137,000 0.2%

LA-5 200 590 0.1% 10,000 28,000 0.0% 15,000 43,000 0.0%

LA-6 530 1,540 0.1% 31,000 90,000 0.1% 44,000 125,000 0.1%

LA-7 100 260 0.1% 4,000 12,000 0.0% 6,000 17,000 0.0%

All Louisiana EIAs 1,930 5,470 – 110,000 313,000 – 161,000 454,000 –

Rest of Louisiana 230 730 – 11,000 34,000 – 20,000 65,000 –

Louisiana Total 2,160 6,180 – 121,000 347,000 – 181,000 517,000 –

Mississippi

MS-1 450 1,400 0.3% 20,000 64,000 0.3% 30,000 94,000 0.3%

MS-2 30 70 0.2% 1,000 2,000 0.1% 1,000 3,000 0.1%

All Mississippi EIAs 480 1,460 – 21,000 65,000 – 31,000 97,000 –

Rest of Mississippi 250 840 – 11,000 39,000 – 19,000 67,000 –

Mississippi Total 730 2,280 – 32,000 103,000 – 50,000 163,000 –

Alabama

AL-1 510 1,650 0.2% 21,000 70,000 0.2% 34,000 115,000 0.2%

AL-2 40 130 0.1% 1,000 5,000 0.1% 3,000 9,000 0.1%

All Alabama EIAs 550 1,780 – 23,000 75,000 – 36,000 124,000 –

Rest of Alabama 200 710 – 10,000 35,000 – 18,000 65,000 –

Alabama Total 760 2,470 – 33,000 110,000 – 54,000 189,000 –

Florida

FL-1 20 150 0.0% 1,000 11,000 0.0% 2,000 18,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 10 20 0.0% 0 1,000 0.0% 1,000 2,000 0.0%

FL-5 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 30 180 – 2,000 12,000 – 3,000 21,000 –

Rest of Florida 220 720 – 12,000 38,000 – 20,000 66,000 –

Florida Total 260 870 – 14,000 48,000 – 24,000 83,000 –

All States

All EIAs in All States 5,630 18,360 – 356,000 1,165,000 – 512,000 1,682,000 –

All Gulf States 6,900 22,420 – 422,000 1,383,000 – 627,000 2,069,000 –
Description of the Affected Environment and Impact Analysis 4-457

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

USA

Rest of the United 

States 1,080 4,680 – 69,000 299,000 – 128,000 564,000 – 

Totals

Total Expenditure 

Impacts 7,980 27,030 – 491,000 1,669,000 – 755,000 2,605,000 – 

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Alternative A would generate government revenues through bonus bids, rental payments, 

and royalty payments. In the low scenario, a regionwide lease sale would generate approximately 

$260 million in bonus bids, $46 million in total rental payments (with an annual peak of $6.7 million), 

and $1.7 billion in royalty payments (with an annual peak of $119 million). In the high scenario, a 

regionwide lease sale would generate approximately $520 million in bonus bids, $98 million in total 

rental payments (with an annual peak of $14 million), and $19.8 billion in total royalty payments (with 

an annual peak of $1.2 billion). The revenue impacts of the very high scenario would be double the 

impacts of the high scenario. The corporate profit and market impacts, the adverse impacts arising 

from routine activities and accidental events, and the cumulative impacts would be proportional to 

the amount of activities as described above.

Overall, Alternative A would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Alternative A would also lead to 

negative economic impacts arising from accidental events and disruptions to other industries. A 

proposed action should be viewed in light of the OCS Program, as well the numerous forces that can 

affect energy markets and the overall economy. Overall, Alternative A would lead to beneficial

impacts, as well as some offsetting negligible to minor adverse impacts that may occur as a result 

of accidental events.

4.14.2.2.6 Alternative B—Regionwide OCS Proposed Lease Sale Excluding Available 

Unleased Blocks in the WPA Portion of the Proposed Lease Sale Area

Alternative B would entail leasing only in the CPA and EPA. As discussed above, the low 

and high scenarios assume that Alternative B is chosen in the context of typically holding two lease 

sales per year. If Alternative B were chosen in the context of the CPA/EPA area only being offered 

once in a year, the economic impacts would be approximately double those presented here because 

leasing activities would not be spread over the two lease sales; the maximum impacts would 

correspond to the very high scenario discussed above.

The positive economic impacts of Alternative B would be slightly less than for Alternative A. 

The MAG-PLAN’s estimates of the total employment, labor income, and value-added impacts for the 

low and high scenarios are presented in Tables 4-40 and 4-41. These tables present the average 
4-458 Gulf of Mexico Multisale EIS

values (over 50 years), peak values, and percent of peak values relative to total employment, labor 

income, and value-added in each EIA. In the low scenario, Alternative B would support a peak of 

7,300 jobs, $440 million in labor income, and $740 million in value-added benefits throughout the 

United States. Most of these impacts would occur in the Gulf of Mexico region, particularly in coastal 

Texas and Louisiana. The EIAs that would experience the highest economic impacts are TX-3, 

TX-2, LA-3, LA-4, LA-6, MS-1, and AL-1. The proportion of total economic impacts would be slightly 

higher in Louisiana, Mississippi, and Alabama and lower in Texas compared with Alternative A. 

However, these impacts would represent small fractions of each EIA’s economy. In the high 

scenario, Alternative B would support a peak of 20,000 jobs, $1.2 billion in labor income, and 

$1.9 billion in value-added. The geographic distributions of impacts would be similar to those of the 

low scenario. However, the expenditure impacts would represent <1 percent of the economies of all 

EIAs. The impacts of the very high scenario would be double the impacts of the high scenario. 

However, as discussed previously, the very high scenario is unlikely to occur. The revenue, 

corporate profit, market, and adverse impacts would also be proportionately lower. The nature of 

potential accidental events would be the same, although slightly fewer activities would likely lead to 

slightly fewer accidental events.

Overall, Alternative B would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Alternative B would also lead to 

negative economic impacts arising from accidental events and disruptions to other industries. 

Alternative B should be viewed in light of the OCS Program, as well the numerous forces that can 

affect energy markets and the overall economy. Overall, Alternative B would lead to beneficial

impacts, as well as some offsetting negligible to minor adverse impacts due to potential accidental 

events. The exact impacts will be roughly proportional to the amount of resulting oil and gas industry 

activity as described above.

Table 4-40. CPA/EPA Single Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak %

Texas

TX-1 10 90 0.0% 0 4,000 0.0% 1,000 7,000 0.0%

TX-2 40 390 0.1% 2,000 19,000 0.1% 3,000 29,000 0.0%

TX-3 160 1,040 0.1% 13,000 85,000 0.1% 20,000 139,000 0.0%

TX-4 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

TX-5 0 20 0.0% 0 1,000 0.0% 0 2,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 210 1,480 – 16,000 107,000 – 24,000 173,000 –

Rest of Texas 50 350 – 3,000 22,000 – 5,000 39,000 –

Texas Total 260 1,830 – 19,000 129,000 – 30,000 212,000 –
Description of the Affected Environment and Impact Analysis 4-459

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak %

Louisiana

LA-1 20 160 0.2% 2,000 12,000 0.2% 2,000 17,000 0.2%

LA-2 0 10 0.0% 0 0 0.0% 0 0 0.0%

LA-3 50 310 0.2% 2,000 14,000 0.1% 4,000 23,000 0.1%

LA-4 60 530 0.3% 4,000 36,000 0.3% 6,000 51,000 0.2%

LA-5 20 190 0.1% 1,000 10,000 0.0% 2,000 15,000 0.0%

LA-6 60 490 0.1% 4,000 29,000 0.1% 5,000 40,000 0.1%

LA-7 10 80 0.1% 0 4,000 0.0% 1,000 6,000 0.0%

All Louisiana EIAs 230 1,760 – 14,000 106,000 – 20,000 152,000 –

Rest of Louisiana 30 220 – 2,000 10,000 – 3,000 21,000 –

Louisiana Total 260 1,970 – 15,000 117,000 – 23,000 173,000 –

Mississippi

MS-1 50 440 0.3% 3,000 23,000 0.3% 4,000 32,000 0.3%

MS-2 0 20 0.2% 0 1,000 0.1% 0 1,000 0.1%

All Mississippi EIAs 50 460 – 3,000 23,000 – 4,000 33,000 –

Rest of Mississippi 40 270 – 2,000 13,000 – 3,000 22,000 –

Mississippi Total 90 720 -- 4,000 36,000 -- 7,000 55,000 --

Alabama

AL-1 60 530 0.2% 3,000 25,000 0.2% 4,000 41,000 0.2%

AL-2 0 40 0.1% 0 2,000 0.1% 0 3,000 0.1%

All Alabama EIAs 60 570 – 3,000 27,000 – 5,000 44,000 –

Rest of Alabama 30 240 – 2,000 12,000 – 3,000 24,000 –

Alabama Total 100 810 – 5,000 39,000 – 8,000 67,000 –

Florida

FL-1 0 60 0.0% 0 4,000 0.0% 1,000 7,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 10 70 – 0 5,000 – 1,000 8,000 –

Rest of Florida 30 220 – 2,000 11,000 – 3,000 21,000 –

Florida Total 40 290 – 2,000 15,000 – 4,000 29,000 –

All States

All EIAs in All States 560 4,340 – 35,000 269,000 – 53,000 411,000 –

All Gulf States 750 5,640 – 45,000 336,000 – 71,000 536,000 –

USA

Rest of the United 

States 180 1,640 – 11,000 104,000 – 21,000 200,000 – 

Totals

Total Expenditure 

Impacts 930 7,280 – 56,000 440,000 – 92,000 736,000 – 

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.
4-460 Gulf of Mexico Multisale EIS

Table 4-41. CPA/EPA Single High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak % 

Texas

TX-1 50 140 0.0% 3,000 7,000 0.0% 4,000 11,000 0.0%

TX-2 220 630 0.1% 11,000 33,000 0.1% 16,000 47,000 0.0%

TX-3 1,740 5,220 0.1% 145,000 435,000 0.1% 199,000 591,000 0.0%

TX-4 10 20 0.0% 0 1,000 0.0% 1,000 2,000 0.0%

TX-5 10 40 0.0% 1,000 2,000 0.0% 1,000 3,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 2,030 6,060 – 160,000 478,000 – 221,000 654,000 –

Rest of Texas 310 860 – 19,000 53,000 – 31,000 90,000 –

Texas Total 2,340 6,930 – 179,000 531,000 – 252,000 744,000 –

Louisiana

LA-1 160 420 0.2% 11,000 29,000 0.2% 16,000 43,000 0.2%

LA-2 10 20 0.0% 0 1,000 0.0% 0 1,000 0.0%

LA-3 420 1,110 0.2% 21,000 55,000 0.1% 31,000 81,000 0.1%

LA-4 430 1,200 0.3% 29,000 80,000 0.3% 42,000 115,000 0.2%

LA-5 200 570 0.1% 9,000 27,000 0.0% 14,000 41,000 0.0%

LA-6 510 1,470 0.1% 30,000 86,000 0.1% 42,000 119,000 0.1%

LA-7 90 250 0.1% 4,000 11,000 0.0% 6,000 16,000 0.0%

All Louisiana EIAs 1,820 5,040 – 104,000 288,000 – 152,000 417,000 –

Rest of Louisiana 190 520 – 9,000 24,000 – 17,000 46,000 –

Louisiana Total 2,010 5,540 – 113,000 312,000 – 168,000 461,000 –

Mississippi

MS-1 440 1,290 0.3% 19,000 57,000 0.3% 29,000 85,000 0.3%

MS-2 30 70 0.2% 1,000 2,000 0.1% 1,000 3,000 0.1%

All Mississippi EIAs 470 1,360 – 20,000 59,000 – 30,000 88,000 –

Rest of Mississippi 210 590 – 9,000 27,000 – 16,000 47,000 –

Mississippi Total 680 1,950 – 29,000 86,000 – 46,000 134,000 –

Alabama

AL-1 500 1,510 0.2% 21,000 63,000 0.2% 33,000 101,000 0.2%

AL-2 40 120 0.1% 1,000 4,000 0.1% 3,000 7,000 0.1%

All Alabama EIAs 540 1,630 – 22,000 67,000 – 35,000 108,000 –

Rest of Alabama 170 490 – 8,000 24,000 – 15,000 44,000 –

Alabama Total 710 2,120 – 30,000 92,000 – 50,000 152,000 –

Florida

FL-1 20 90 0.0% 1,000 6,000 0.0% 2,000 11,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 1,000 0.0% 0 1,000 0.0%

FL-5 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 30 110 – 1,000 7,000 – 3,000 13,000 –

Rest of Florida 190 510 – 10,000 27,000 – 17,000 46,000 –

Florida Total 220 610 – 12,000 33,000 – 20,000 57,000 –

All States

All EIAs in All States 4,890 14,190 – 307,000 899,000 – 440,000 1,278,000 –

All Gulf States 5,950 17,140 – 363,000 1,054,000 – 536,000 1,549,000 –
Description of the Affected Environment and Impact Analysis 4-461

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

USA

Rest of the United 

States 890 2,990 – 57,000 192,000 – 106,000 358,000 – 

Totals

Total Expenditure 

Impacts 6,840 20,140 – 420,000 1,246,000 – 642,000 1,907,000 – 

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

4.14.2.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

Alternative C would entail leasing only in the WPA. As discussed above, the low and high 

scenarios assume that Alternative C is chosen in the context of typically holding two lease sales per 

year. If Alternative C were chosen in the context of the WPA area only being offered once in a year, 

the economic impacts would be approximately double those presented here because leasing 

activities would not be spread over the two lease sales; the maximum impacts would correspond to 

the very high scenario discussed above.

The positive economic impacts of Alternative C would be less than for Alternative A, 

particularly since less activity generally occurs in the WPA relative to the CPA. MAG-PLAN’s 

estimates of the total employment, labor income, and value-added impacts for the low and high 

scenarios are presented in Tables 4-42 and 4-43. These tables present the average values (over 

50 years), peak values, and the percent of peak values relative to total employment, labor income, 

and value-added in each EIA. In the low scenario, Alternative C would support a peak of 2,300 jobs, 

$140 million in labor income, and $230 million in value-added benefits throughout the United States. 

Most of these impacts would occur in the Gulf Region. The EIAs that would experience the highest 

economic impacts are TX-3, TX-2, TX-1, LA-4, and AL-1. The proportion of total economic impacts 

would be higher in Texas (and lower in the other Gulf States) compared to Alternative A. However, 

these impacts would represent small fractions of each EIAs economy. In the high scenario, 

Alternative C would support a peak of 6,900 jobs, $420 million in labor income, and $700 million in 

value-added. The geographic distributions of impacts would be similar to those of the low scenario. 

The impacts of the very high scenario would be double the impacts of the high scenario. However, 

as discussed previously, the very high scenario is unlikely to occur. The revenue, corporate profit, 

market, and adverse impacts would also be proportionately lower. The nature of potential accidental 

events would be the same, although slightly fewer activities would likely lead to slightly fewer 

accidental events.

Overall, Alternative C would lead to beneficial impacts arising from industry expenditures, 

government revenues, corporate profits, and other market impacts. Alternative C would also lead to 

negative economic impacts arising from accidental events and disruptions to other industries. 
4-462 Gulf of Mexico Multisale EIS

Alternative C should be viewed in light of the OCS Program, as well the numerous forces that can 

affect energy markets and the overall economy. Overall, Alternative C would lead to beneficial

impacts, as well as some offsetting negligible to minor adverse impacts mostly as a result of 

accidental events that may be reasonably foreseeable. The exact impacts will be roughly 

proportional to the amount of resulting oil and gas industry activity as described above.

Table 4-42. WPA Single Low: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts (number of 

jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak % 

Texas

TX-1 10 130 0.0% 0 4,000 0.0% 1,000 6,000 0.0%

TX-2 20 220 0.1% 1,000 10,000 0.1% 2,000 15,000 0.0%

TX-3 100 860 0.1% 7,000 65,000 0.1% 11,000 102,000 0.0%

TX-4 0 10 0.0% 0 0 0.0% 0 0 0.0%

TX-5 0 30 0.0% 0 2,000 0.0% 0 3,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 130 1,180 – 9,000 77,000 – 13,000 121,000 –

Rest of Texas 10 110 – 1,000 7,000 – 1,000 12,000 –

Texas Total 150 1,290 – 10,000 84,000 – 15,000 133,000 –

Louisiana

LA-1 0 0 0.2% 0 0 0.2% 0 0 0.2%

LA-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

LA-3 0 30 0.2% 0 2,000 0.1% 0 3,000 0.1%

LA-4 10 70 0.3% 0 4,000 0.3% 1,000 6,000 0.2%

LA-5 0 10 0.1% 0 0 0.0% 0 1,000 0.0%

LA-6 0 20 0.1% 0 1,000 0.1% 0 2,000 0.1%

LA-7 0 0 0.1% 0 0 0.0% 0 0 0.0%

All Louisiana EIAs 20 110 – 1,000 7,000 – 1,000 10,000 –

Rest of Louisiana 10 80 – 0 4,000 – 1,000 7,000 –

Louisiana Total 20 180 – 1,000 9,000 – 2,000 16,000 –

Mississippi

MS-1 0 30 0.3% 0 2,000 0.3% 0 3,000 0.3%

MS-2 0 0 0.2% 0 0 0.1% 0 0 0.1%

All Mississippi EIAs 0 30 – 0 2,000 – 0 3,000 –

Rest of Mississippi 10 90 – 0 4,000 – 1,000 7,000 –

Mississippi Total 10 110 – 1,000 5,000 – 1,000 9,000 –

Alabama

AL-1 0 70 0.2% 0 3,000 0.2% 0 7,000 0.2%

AL-2 0 0 0.1% 0 0 0.1% 0 0 0.1%

All Alabama EIAs 0 70 – 0 3,000 – 0 7,000 –

Rest of Alabama 10 70 – 0 3,000 – 1,000 7,000 –

Alabama Total 10 120 – 1,000 6,000 – 1,000 13,000 –

Florida

FL-1 0 30 0.0% 0 2,000 0.0% 0 4,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%
Description of the Affected Environment and Impact Analysis 4-463

Economic 

Impact Area

Employment Impacts (number of 

jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak % Average Peak Peak 

% Average Peak Peak %

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 0 30 – 0 2,000 – 0 4,000 –

Rest of Florida 10 70 – 0 3,000 – 1,000 6,000 –

Florida Total 10 90 – 1,000 5,000 – 1,000 9,000 –

All States

All EIAs in All States 160 1,400 – 10,000 89,000 – 16,000 139,000 –

All Gulf States 210 1,790 – 13,000 109,000 – 20,000 177,000 –

USA

Rest of the United 

States 50 500 – 3,000 32,000 – 6,000 62,000 – 

Totals

Total Expenditure 

Impacts 250 2,260 – 16,000 139,000 – 26,000 234,000 – 

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

Table 4-43. WPA Single High: MAG-PLAN Industry Expenditure Impacts.

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak % 

Texas

TX-1 40 340 0.0% 2,000 12,000 0.0% 2,000 18,000 0.0%

TX-2 110 680 0.1% 5,000 33,000 0.1% 8,000 48,000 0.0%

TX-3 430 2,420 0.1% 32,000 182,000 0.1% 47,000 274,000 0.0%

TX-4 0 20 0.0% 0 1,000 0.0% 0 2,000 0.0%

TX-5 20 110 0.0% 1,000 5,000 0.0% 2,000 9,000 0.0%

TX-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Texas EIAs 600 3,430 – 41,000 227,000 – 60,000 342,000 –

Rest of Texas 60 330 – 3,000 20,000 – 6,000 36,000 –

Texas Total 660 3,720 – 44,000 247,000 – 66,000 378,000 –

Louisiana

LA-1 0 10 0.2% 0 0 0.2% 0 1,000 0.2%

LA-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

LA-3 40 120 0.2% 2,000 7,000 0.1% 3,000 10,000 0.1%

LA-4 40 260 0.3% 3,000 15,000 0.3% 4,000 22,000 0.2%

LA-5 10 20 0.1% 0 1,000 0.0% 0 2,000 0.0%

LA-6 20 70 0.1% 1,000 5,000 0.1% 2,000 6,000 0.1%

LA-7 0 10 0.1% 0 1,000 0.0% 0 1,000 0.0%

All Louisiana EIAs 110 430 – 6,000 25,000 – 9,000 37,000 –

Rest of Louisiana 40 200 – 2,000 10,000 – 3,000 19,000 –

Louisiana Total 150 640 – 8,000 35,000 – 12,000 56,000 –
4-464 Gulf of Mexico Multisale EIS

Economic 

Impact Area

Employment Impacts 

(number of jobs)

Labor Income Impacts 

($ thousands)

Value-Added Impacts 

($ thousands)

Average Peak Peak 

% Average Peak Peak % Average Peak Peak %

Mississippi

MS-1 10 110 0.3% 1,000 7,000 0.3% 1,000 9,000 0.3%

MS-2 0 0 0.2% 0 0 0.1% 0 0 0.1%

All Mississippi EIAs 10 110 – 1,000 7,000 – 1,000 10,000 –

Rest of Mississippi 40 240 – 2,000 11,000 – 3,000 20,000 –

Mississippi Total 50 330 – 3,000 17,000 – 4,000 28,000 –

Alabama

AL-1 10 140 0.2% 1,000 7,000 0.2% 1,000 14,000 0.2%

AL-2 0 10 0.1% 0 0 0.1% 0 1,000 0.1%

All Alabama EIAs 10 150 – 1,000 7,000 – 1,000 15,000 –

Rest of Alabama 30 220 – 2,000 11,000 – 3,000 21,000 –

Alabama Total 50 350 – 2,000 18,000 – 4,000 37,000 –

Florida

FL-1 10 60 0.0% 0 4,000 0.0% 1,000 7,000 0.0%

FL-2 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-3 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-4 0 10 0.0% 0 0 0.0% 0 1,000 0.0%

FL-5 0 0 0.0% 0 0 0.0% 0 0 0.0%

FL-6 0 0 0.0% 0 0 0.0% 0 0 0.0%

All Florida EIAs 10 70 – 0 5,000 – 1,000 9,000 –

Rest of Florida 30 210 – 2,000 11,000 – 3,000 20,000 –

Florida Total 40 270 – 2,000 14,000 – 4,000 26,000 –

All States

All EIAs in All States 750 4,170 – 49,000 266,000 – 72,000 404,000 –

All Gulf States 950 5,280 – 59,000 329,000 – 91,000 520,000 –

USA

Rest of the United States 190 1,680 – 12,000 106,000 – 23,000 206,000 –

Totals

Total Expenditure Impacts 1,130 6,890 – 71,000 423,000 – 113,000 698,000 –

EIA = Economic Impact Area.

Note: Totals may not sum due to rounding.

Source: BOEM internal modeling estimates.

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

Alternative D only slightly reduces the available areas for leasing. Therefore, the economic 

impacts of Alternative D would the same or only slightly less than the impacts of Alternative A, B, 

or C.

4.14.2.2.9 Alternative E—No Action

The selection of Alternative E would prevent the positive economic impacts described above 

from occurring; it would also prevent the associated negative impacts from occurring. Since the 

OCS Program generally supports existing oil and gas activities, Alternative E would negatively 
Description of the Affected Environment and Impact Analysis 4-465

While the entire petroleum 

industry (onshore, State 

waters, and OCS) has 

developed over decades and 

is deeply intertwined in the 

Gulf of Mexico region’s 

communities and economies, 

a single lease sale is like a 

blip on a radar screen, one 

tiny piece of a vastly complex 

social and economic structure.

impact firms and employees that depend on recurring leases. Prices and quantities sold of energy 

products would adjust slightly to the removal of oil and gas from the market. The selection of 

Alternative E relates only to a single proposed lease sale, while decisions regarding the broader 

leasing program are made at the Five-Year Program stage. Therefore, the impacts of Alternative E 

would be negligible to minor, with some partially offsetting beneficial impacts.

4.14.3 Social Factors (Including Environmental Justice) 

The petroleum industry as a whole in the Gulf of Mexico 

region has matured over several decades and is well-developed, 

expansive, extensive, and deeply intertwined in the regional 

communities and economies of the five coastal states, i.e., 

Texas, Louisiana, Mississippi, Alabama, and Florida. An 

inherent complication in conducting an impact analysis of OCS 

oil- and gas-related activities lies in the fact that the industry 

involves onshore (private and public lands), State offshore, and 

Federal OCS exploration, development, and production. 

Teasing out the OCS oil- and gas-related impacts from the 

impacts of activities onshore and in State waters is complex. 

Moreover, this long-lived, well-developed, and extensive industry 

functions within a much larger context, a socioeconomic 

framework that weaves through the region in a complex, inter-connected, grid-like manner. Nothing 

occurs as an isolated event, but rather results from and simultaneously triggers other events, all of 

which are experienced at varying degrees of a negative or positive impact. For example, when oil 

prices drop and then gasoline prices drop, this positively impacts individuals and businesses who 

buy fuel. When oil prices remain low for many months, negative impacts begin to appear. 

Companies start trimming costs by reducing the number of employees to cut operational costs. 

Laid-off employees no longer have income to make purchases and the businesses where workers 

would normally spend their money began to suffer and, when necessary, people began moving out 

of the area to find other work, leading to a negative impact on the housing market, depressing real 

estate prices as the number of units available for rent or sale outgrows the demand. A negative 

impact for some (i.e., sellers and landlords) becomes a positive impact for others (i.e., buyers and 

renters). This is just one example of an event unrelated to OCS oil- and gas-related activities 

leading to dual ripple impacts (negative and positive) through communities and illustrates the 

complexity of the socioeconomic framework. Within this context, and in the cumulative analysis, a 

single lease sale is like a blip on a radar screen, one tiny piece of a vastly complex social and 

economic structure. A single proposed lease sale’s main impact on communities would be to 

contribute to the maintenance of current employment levels; not to create new jobs; not to cause a 

notable increase of people to move into the region; not to cause new roads, schools, or hospitals to 

be built; and not to cause large public works improvements. A proposed single lease sale would 

mostly solely help to maintain what decades of economic development have built, the complex Gulf 

of Mexico region that exists today.
4-466 Gulf of Mexico Multisale EIS

While this chapter is titled “social factors,” the resource discussed here is essentially human 

beings. The list of potential impact-producing factors is, in a sense, nearly limitless because the 

industry involves people at all levels; it simultaneously affects and is affected by people, their 

communities, and their daily lives. Most of the impacts to people are positive, e.g., in the form of 

direct employment in the industry, indirect employment in the extensive support sectors, and 

employees’ spent wages and tax revenues that support the community businesses and services. 

After describing the affected environment, this impact analysis addresses routine activities related to 

the oil and gas industry and accidental events that may occur from OCS oil- and gas-related 

activities as a result of a single lease sale, as well as the cumulative impacts of OCS oil- and gasrelated and non-OCS oil- and gas-related impact-producing factors. An environmental justice

determination follows in Chapter 4.14.3.3. 

Impact-Level Definitions

Impacts to people and communities may be positive as well as negative. For example, 

increased economic demand would lead to more hiring, and this additional employment would 

further the positive economic trend as new workers spend their wages in the community. The 

following scale defines the impact measures for this analysis:

• Beneficial – Positive impacts such as any of the following: maintaining current 

employment levels; creating new employment; and indirect and induced positive 

impacts through increased spending that stimulates local and regional 

economies.

• Negligible – Little or no measureable adverse impact.

• Minor – Small-scale measurable adverse impact, temporary in duration, and 

geographically small area (less than county/parish level).

• Moderate – Medium-scale measurable adverse impact, may last from a few 

weeks to 1 year, and geographically may affect multiple counties/parishes.

• Major – Large-scale measurable or potentially unmeasurable adverse impact, 

long lasting (1 year to many years), and may occur over a geographically large 

regional area.

4.14.3.1 Description of the Affected Environment

The affected environment that comprises the baseline for the social factors’ environmental 

impact analysis is geographically distributed across 23 BOEM-identified EIAs in all five Gulf Coast 

States. Figure 4-32 shows the aggregation of 133 counties and parishes that comprise the EIAs. 

Chapter 4.14.2 (Economic Factors) discusses the methodology behind the development of the EIAs 

and employment in the analysis area.
Description of the Affected Environment and Impact Analysis

4-467

Figure 4-32. Population of BOEM’s Economic Impact Areas in the Gulf of Mexico.
4-468 Gulf of Mexico Multisale EIS

The U.S. Census Bureau’s calculations estimate that the total population of the combined 

BOEM economic impact areas exceeded 22.7 million in 2014. Figure 4-32 presents the range of 

population levels by county/parish across the GOM coastal region. County and parish population 

levels vary greatly across the coastal GOM. For example, Kenedy County, Texas, holds the low end 

of the range with 400 residents and Harris County, Texas, tops out the range at more than 

11,000 times that number (4,441,370). At the low end of the population spectrum, 42 (or nearly onethird) of 133 counties/parishes in BOEM’s EIAs have less than 25,000 residents. In the upper range, 

other counties with the >500,000 residents include Hillsborough County, Florida (1,316,298); 

Pinellas County, Florida (938,098); Hidalgo County, Texas (831,073); Fort Bend County, Texas 

(685,345); Lee County, Florida (679,513); Polk County, Florida (634,638); and Montgomery County, 

Texas (518,947) (USDOC, Census Bureau, 2014).

Population in the coastal regions of Gulf Coast States increased 150 percent from 1960 

through 2008 and continues to grow. There are 23 states in the U.S. with coastline populations, and 

the 5 Gulf Coast States occupy over 25 percent of the total for the coastal population of the U.S. Of 

the eight U.S. coastal counties with the fastest growth, six Gulf Coast counties posted the highest 

percentage of increase—from Lee County, Florida, at 1,091.5 percent to Collier County, Florida, at 

1,901.3 percent. In the nearly five decades from 1960 to 2008, the Gulf of Mexico coastal 

counties/parishes increased their populations by 246 percent, which is more than 52 percent greater 

than Pacific coastal counties (130%) and well over two-times as great as the Atlantic area (98%) 

(USDOC, Census Bureau, 2010a and 2010b; USDOC, NOAA, 2011).

Population density refers to the number of persons per square mile that live in a 

geographically defined area. In the GOM, the counties/parishes with the highest population density 

(persons per square mile) are Pinellas County, Florida (3,348); Harris County, Texas (2,402); 

Orleans Parish, Louisiana (2,029); Jefferson Parish, Louisiana (1,463); and Hillsborough County, 

Florida (1,205). Three of these top five counties/parishes have a high concentration of oil and gas 

industry in addition to hosting large cities: Harris County (Houston, Texas); and Orleans and 

Jefferson Parishes (Louisiana).

Of all 133 counties/parishes in BOEM’s EIAs, Harris County, Texas, holds the largest 

number of oil- and gas-related companies and associated support infrastructure (Petterson et al., 

2008; Dismukes, 2011; Kaplan, et al., 2011). Additional counties and parishes with strong ties to the 

oil and gas industry include Galveston, Jefferson, Brazoria, and Nueces Counties, Texas; Jefferson, 

Plaquemines, Orleans, St. Bernard, Lafourche, Terrebonne, St. Mary, Vermilion, Cameron, and 

Calcasieu Parishes, Louisiana; Jackson County, Mississippi; and Mobile County, Alabama (Kaplan 

et al., 2011).

In the Gulf Coast region, the annual median household income at $41,203 is about 5 percent 

below the national average of $43,462 (USDOC, Census Bureau, 2010b). Figures 4-33 and 4-34

illustrate poverty levels across the GOM. Within the 133 counties/parishes that comprise BOEM’s 

EIAs, 78 percent or 104 counties/parishes have poverty levels above the national average of 

14.5 percent. The highest concentration of poverty is in TX-1 where 8 out of 11 counties have more 
Description of the Affected Environment and Impact Analysis 4-469

than 30 percent of their population living below the national poverty level. Willacy County, Texas, 

has the highest poverty level (40%) and Fort Bend County, Texas, has the lowest poverty level 

(8.4%) (USDOC, Census Bureau, 2013a and 2013b).

Figure 4-33. Percentage of Poverty in Texas and Louisiana.

Figure 4-34. Percentage of Poverty in Mississippi, Alabama, and Florida.
4-470 Gulf of Mexico Multisale EIS

The average percentage of minority residents throughout the 23 BOEM-identified EIAs is 

22.9 percent, which is slightly below the national average of 26 percent. Forty-four 

counties/parishes have minority population levels above the national average. Figures 4-35

and 4-36 illustrate the distribution of minority populations across the five Gulf Coast States. Five 

parishes in Louisiana (i.e., Orleans, St. John the Baptist, St. James, East Baton Rouge, and 

Iberville) and one county in Florida (Gadsden) have over a 50-percent minority population. Orleans 

Parish, Louisiana, has the highest concentration of minority residents at 66.4 percent, while the 

lowest percentage is shared by two Texas counties, Kenedy and Zapata Counties, at 1.7 percent 

(USDOC, Census Bureau, 2013c).

Figure 4-35. Percentage of Minority Populations in Texas and Louisiana.
Description of the Affected Environment and Impact Analysis 4-471

Figure 4-36. Percentage of Minority Populations in Mississippi, Alabama, and Florida.

4.14.3.2 Environmental Consequences

A regionwide proposed lease sale is the preferred alternative and, just like planning area 

specific lease sales, involves all of the Gulf Coast States (i.e., Texas, Louisiana, Mississippi, 

Alabama, and Florida) because the onshore effects operate independently of the boundaries of 

offshore planning areas. Particular emphasis is placed on the 133 counties and parishes that 

constitute the 23 BOEM-identified EIAs and that are located in the coastal areas of all five states. 

Figure 4-29 shows the aggregation of counties and parishes into the EIAs used for BOEM’s 

socioeconomic analysis. This geographic area possesses a culturally and racially diverse 

population. Some counties and parishes are more closely connected to the offshore oil and gas 

industry than others particularly Harris County, Texas, and Lafourche Parish, Louisiana. An analysis 

and discussion of the impact-producing factors from routine activities, accidental events, and 

cumulative activities is presented below. For a detailed analysis of a high-impact, low-probability 

catastrophic oil spill, refer to the Catastrophic Spill Event Analysis white paper (USDOI, BOEM, 

2017).

Analysis of the various alternatives considers impact-producing factors within a distinct 

framework that includes frequency, duration, and geographic extent. Frequency (i.e., rare, 

intermittent, and continuous) refers to how often the impact-producing factor occurs over the entire 

analysis period of 50 years for routine activities and accidental events and for an analysis period of 

70 years for cumulative impacts. Duration (i.e., low, medium, and high) refers to how long the 

impact-producing factor lasts (i.e., from less than a year to many years). Geographic extent refers to 

which areas are affected and, depending on the impact-producing factor, the size of an affected 

area.
4-472 Gulf of Mexico Multisale EIS

Routine activities related to a 

single lease sale would be 

incremental in nature, not 

expected to change existing 

conditions, and positive in 

their contribution to the 

sustainability of current 

industry and related support 

services and employment. 

4.14.3.2.1 Routine Activities

People and communities are a major part of, and 

provide basic support for, the oil and gas industry. An analysis 

of the impacts of the industry’s routine activities (described in 

Chapter 3.1) on people and communities is complex because 

they are experienced at multiple levels that overlap, i.e., 

industry workers, families of workers, and the communities at 

large. Impacts occur in varying degrees of intensity. The 

interactions of industry and community are complex, resulting in 

a myriad of impacts, some positive and some negative. This 

complex relationship between industry and the community 

evolves over time, and the subsequent impacts evolve accordingly. Impact-producing factors related 

to routine activities can be experienced as positive or negative, depending on the specifics of any 

given situation, and cover a broad spectrum, i.e., employment stability, wages and opportunities for 

advancement, economic rewards in exchange for work (benefits), work scheduling patterns and how 

these dictate time spent off the job or with families, industry cycles and fluctuations in OCS oil- and 

gas-related activity levels, demographic shifts (in-migration and out- migration), commuter and truck 

traffic, commodity (oil/gas) price fluctuations, expansions of existing infrastructure, and new 

construction of infrastructure.

The oil and gas industry has evolved in the GOM for many decades, simultaneously affecting 

and being affected by the societal and economic conditions in the region. Because of this 

long-standing, complex interrelationship, the impacts of the oil and gas industry as a whole have 

been diverse and widespread over many years. Austin et al. (2002) and Austin and McGuire (2002) 

describe this complexity from the viewpoint of workers and their families, and they found that 

impacts are experienced at many different levels and intensities depending on what sector of the 

industry is involved. For example, workers in the production sector enjoy more stable employment, 

while the drilling sector is volatile and provides less secure employment because it is more easily 

affected by fluctuations in oil and gas prices.

Employment stability in the oil and gas industry and its support sectors correlates directly 

with fluctuations in OCS oil- and gas-related activity levels, which are, in turn, closely related the 

changes in oil and gas commodity prices. Scott (2014) describes how important and influential the 

extraction, refining, and pipeline sectors of the oil and gas industry are for the State of Louisiana, 

from supporting over 287,000 jobs to paying nearly $1.5 billion in taxes to the State for 1 year alone. 

While the residents and communities of Louisiana enjoy unquestionable economic benefits, they 

also are most impacted by fluctuations in OCS oil- and gas-related activity levels and oil and gas 

prices. Petterson et al. (2008) describe how the benefits and burdens of the oil and gas industry are 

distributed unevenly across Texas, Louisiana, Mississippi, Alabama, and Florida, with some states 

(Texas and especially Louisiana) bearing the most burdens, while others accrue the benefits without 

suffering the burdens of hosting oil- and gas-related activities (e.g., Florida). This is further 

illustrated by Donato (2004) and Aratame and Singelmann (2002), who examine demographic shifts 
Description of the Affected Environment and Impact Analysis 4-473

in Louisiana and the region related to the changing labor situation in the region, from the generally 

positive impact of immigrant workers to the commuting and migration trends from noncoastal to 

coastal communities following fluctuations in labor demand across the region.

The potential impacts resulting from the industry’s routine activities occur within the larger 

socioeconomic context of the GOM region. Given the existing, extensive, and widespread support 

system for the OCS oil- and gas-related industry and its associated labor force, the impacts of 

routine activities related to a single lease sale are expected to be negligible, widely distributed, and 

to have little impact. Routine activities related to a single lease sale would be incremental in nature, 

not expected to change existing conditions, and positive in their contribution to the sustainability of 

current industry, related support services, and associated employment. 

4.14.3.2.2 Accidental Events

Accidental events related to OCS oil- and gas-related activities that could affect people and 

communities include oil spills, chemical/drilling-fluid spills, spill response, and vessel collisions. 

These events are described in Chapter 3.2. This section considers small-scale oil spills that have a 

greater probability of occurring. Potential oil spills, including surface spills and underwater well

blowouts, may be associated with exploration, production, or transportation phases of a proposed

lease sale. A detailed risk analysis of offshore oil spills and coastal spills associated with a 

proposed lease sale can be found in Chapter 3.2.1. Large spills (≥1,000 bbl) are much less 

frequent but may be reasonably foreseeable and are therefore considered within this Multisale EIS; 

in contrast, a catastrophic event of a magnitude similar to the Deepwater Horizon explosion, oil spill, 

and response is not reasonably foreseeable and not part of a proposed action. Because spills 

<1,000 bbl are not expected to persist as a slick on the surface of the water beyond a few days and 

because spills on the OCS would occur at least 3-10 nmi (3.5-11.5 mi; 5.6-18.5 km) from shore, it is 

unlikely that any spills would make landfall prior to breaking up. . The combined probabilities for an 

offshore spill ≥1,000 bbl occurring and contacting coastal and offshore areas for each alternative can 

be found in the figures in Appendix E. For a proposed action, the probabilities of an oil spill 

≥1,000 bbl occurring and contacting the shoreline within 10 days range from <0.5-1 percent to 

2-8 percent, with the highest probability in Plaquemines Parish, Louisiana, at 1-6 percent 

(Figure E-2). The probabilities of oil spills ≥1,000 bbl occurring and contacting the shoreline within 

30 days range from <0.5-1 percent to 2-8 percent, with the highest probability in Plaquemines 

Parish, Louisiana, at 2-8 percent (Figure E-3). Oil spills that occur in coastal or nearshore waters 

have a greater chance of directly affecting people and communities. Most small-scale oil spills are 

short in duration and have impacts ranging from negligible to moderate. Similarly, the impacts of 

chemical and drilling-fluid spills depend on the location of the spill, with closer to shore proximity 

increasing the likelihood of negative impacts, which can range from negligible to moderate, 

depending on the specific characteristics of the event. Vessel collisions also may affect local 

populations as they often result in oil or chemical spills and may interrupt transportation along 

waterways or roadways if a bridge is involved. Small-scale, noncatastrophic events involve varying 

degrees of spill response and containment. Spill-response activities are expected to have 

negligible to moderate impacts to people and communities, and these impacts also depend on the 
4-474 Gulf of Mexico Multisale EIS

location and scale of the event being addressed. For example, if an accidental event is very small 

(not measurable) in size, affects a small geographic area, and is of short duration, its impact would 

be negligible. If an accidental event is measurable, covers a larger geographic area, and lasts a 

few days to a month, then its impact would be minor. If an accidental event affects a more than one 

county or parish, is measurable with impacts lasting up to 1 year, then the impact would be 

moderate. 

For a detailed discussion of a low-probability, catastrophic oil spill, refer to the Catastrophic 

Spill Event Analysis white paper (USDOI, BOEM, 2017). Also, a BOEM-funded study (Austin et al., 

2014b and 2014c) researched and documented the complex and varied social impacts of the 

Deepwater Horizon explosion, oil spill, and response. This study found that the impacts of the spill 

on a particular community depended on a number of factors, such as social and political dynamics, 

proximity to the spill, economic structure, organizational structure for dealing with disasters, and 

ability to adapt to the oil cleanup and damage claims processes. With the exception of a 

catastrophic accidental event, such as the Deepwater Horizon explosion, oil spill, and response,

the impacts of oil spills, chemical/drilling-fluid spills, vessel collision, and spill-response activities are 

not likely to be of sufficient duration to have adverse and disproportionate long-term impacts for 

people and communities in the analysis area.

4.14.3.2.3 Cumulative Impacts

People and communities experience cumulative impacts that include all human activities and 

natural processes and events. The cumulative analysis considers the incremental contribution of a 

proposed lease sale when combined with the natural baseline conditions and the cumulative effects 

of all past, present, and future OCS oil- and gas-related lease sales and activities, as well as all past, 

present, and reasonably foreseeable future actions that are external to OCS oil- and gas-related 

activities (described in Chapter 3.3).

The cumulative analysis geographically includes all 133 counties that comprise the 

23 BOEM-identified EIAs, covering the coastal areas of all five Gulf Coast States from the southern 

tip of Texas to the Florida Keys. Temporally, the nautral baseline conditions were those in existence 

before the first Federal OCS lease sale in 1954, several decades ago. At that time, population in the 

five Gulf Coast States was only 19.8 million, much less than half of the 60.3 million residents in 2015 

(USDOC, Census Bureau, 2015a, 2015b, 2015c, 2015d, and 2015e) (Table 4-32).

The coastal areas experienced the greater proportion of population growth over the years 

(USDOC, NOAA, 2011). Though coastal areas were less developed and more rural in 1954, there 

was much cultural variation across the region, especially in Louisiana (White, 1998). However, the 

oil and gas industry had been thirving in Texas and Louisiana since 1901 with the Beaumont, Texas, 

Spindletop discovery and the first Louisiana oil well in Jennings (Austin et al., 2008; Texas Almanac, 

n.d.; State of Louisiana, Dept. of Natural Resources, n.d.). All manner of oil and gas infrastructure

developed over the decades from 1901 to 1954. The onshore oil and gas industry developed and 

matured from 1901 to 1954, bringing many jobs and economic opportunity to the area. The 1950’s 
Description of the Affected Environment and Impact Analysis 4-475

marked one of the most prosperous time periods for the United States, with more wealth being 

created from 1950 to 1965 than in any previous era (Arabe, 2003). When the Federal Government 

decided to formalize its control over the OCS in 1953, the oil and gas industry was already booming 

onshore and in coastal waters along the Gulf Coast.

The Submerged Lands Act and the OCSLA, both passed in 1953, laid the foundation for the 

creation of the Federal OCS Program. The first lease sale of OCS lands in the Gulf of Mexico 

occurred on October 13, 1954. Since that time, in the Gulf of Mexico region, the Federal OCS 

Program has held over 120 lease sales, leasing in excess of 143 million ac (58 million ha), with over 

$66 billion in total bonuses for leased blocks (USDOI, BOEM, 2016g). The past and present OCS 

Programs (with >120 lease sales) have occurred simultaneously with numerous non-OCS oil- and 

gas-related past and present activities that, when taken in their entirety, have resulted in the current 

make-up of the analysis area (refer to Figure 4-29 and Figures 4-32 through 4-36 and the 

“Description of the Affected Environment” above). BOEM adds to this all reasonably forseeable 

future OCS oil- and gas-related and non-OCS oil- and gas-related activities to complete the 

cumulative analysis within the geographical bounds of the 23 BOEM-identified EIAs spanning across 

133 counties and parishes.

Incremental Contribution

This complex analytical framework is divided into discussions of OCS oil-and gas-related and 

non-OCS oil- and gas-related impacts. The largest quantity of impact-producing factors for people 

and communities occur as non-OCS oil- and gas-related impacts because OCS oil- and gas-related 

activities form such a small part of the greater, complex socioeconomic structure in the GOM. The 

incremental contribution to cumulative impacts of a proposed action (i.e., a single proposed lease 

sale) would be minor for communities and people in the Gulf Coast region.

OCS Oil- and Gas-Related Impacts

A proposed lease sale, when combined with natural baseline conditions and the cumulative 

effects of all past, present, and future OCS oil- and gas-related lease sales and activities resulting 

from the OCS Program, contributes to the following impacts:

• employment and wage stability;

• opportunities for advancement;

• economic rewards in exchange for work (benefits);

• work scheduling patterns and how these dictate time spent off the job or with 

families;

• industry cycles with fluctuations in OCS oil- and gas-related activity levels;

• demographic shifts (in-migration and out- migration);

• commuter and truck traffic; commodity (oil/gas) price fluctuations;
4-476 Gulf of Mexico Multisale EIS

• expansions of existing infrastructure; 

• new construction of infrastructure; 

• coastal and offshore oil spills; 

• chemical/drilling-fluid spills;

• spill-response activities; and

• vessel collisions. 

The OCS Program could result in only minor economic changes and generally contributes to 

maintaining current employment levels. Consisting of 10 proposed regionwide lease sales between 

2017 and 2022, the current Gulf of Mexico OCS Program, when combined with all past, present and 

future programs, would contribute cumulatively to employment and population fluctuations, 

infrastructure changes, and/or traffic impacts because of local concentrations of fabrication and 

supply operations. Given its extensive oil-related support system and dependence on revenues 

generated by the industry, Louisiana is likely to experience more positive or negative employment 

impacts related to a proposed lease sale and the OCS Program than are the other coastal states. 

For example, Lafourche Parish, Louisiana, already services about 90 percent of all deepwater

oil production and 45 percent of all shallow-water oil and gas production in the Gulf, and it is likely 

to continue experiencing benefits from the OCS Program (Scott, 2014). The OCS Program in the 

cumulative analysis would serve to maintain current activity levels, which is expected to be 

beneficial to the GOM as a whole.

With the exception of a low-probability catastrophic accidental event, such as the 

Deepwater Horizon explosion, oil spill, and response, which is not reasonably foreseeable and is not 

part of a proposed action, the impacts of oil spills, chemical/drilling-fluid spills, vessel collision, and 

spill-response activities are not or are not likely to be of sufficient duration to have adverse and 

disproportionate long-term impacts for people and communities in the analysis area (refer to 

Catastrophic Spill Event Analysis white paper, USDOI, BOEM, 2017). Research into possible 

long-term health impacts of the Deepwater Horizon explosion, oil spill, and response is ongoing 

(National Institute of Environmental Health Science, 2014; National Center for Disease 

Preparedness, 2013 and 2014; Substance Abuse and Mental Health Services Administration and 

Centers for Disease Control and Prevention, 2013).

In the unlikely case of a large-scale catastrophic accidental event, which is statistically 

unlikely and therefore not part of a proposed action, short-term and long-term health impacts may 

occur. However, BOEM has prepared a Catastrophic Spill Event Analysis white paper to disclose 

the potential impacts associated with such an event (USDOI, BOEM, 2017). Comments were 

received on the Draft Multisale EIS regarding the impacts of the Deepwater Horizon explosion, oil 

spill, and response on public health, especially workers and people living in coastal communities. 

Studies conducted since the 2010 oil spill have been evaluating potential physical and psychological 

health impacts of response workers and people in coastal communities (Blackmon et al., 2016; 
Description of the Affected Environment and Impact Analysis 4-477

Non-OCS oil- and gas-related

factors are greater in number 

and actually contribute much

more to the cumulative 

impacts on people and 

communities than do factors 

related to OCS oil- and gasrelated activities because of 

the analysis area’s complex 

socioeconomic framework.

Gould et al., 2016; Gratten et al., 2011; Hansel et al., 2015; Peres et al., 2016). Early worker and 

shoreline monitoring data indicated that the concentrations of oil and dispersants to which 

low-income and minority communities may have been exposed were unlikely to result in adverse 

health effects (King and Gibbons, 2011; Middlebrook et al., 2011; U.S. Dept. of Labor, OSHA, 2010a 

and 2010b). Later studies looking at lung health reached different conclusions about the effects of 

dispersants on those exposed to airborne particles (Liu et al., 2015; Major et al., 2016). Another 

concern was that heavy subsistence users may have faced higher than expected and potentially 

harmful exposure rates to PAHs from the Deepwater Horizon explosion, oil spill, and response. 

However, fisheries closures may have temporarily limited access to subsistence foods, thereby also 

reducing the potential of oil dispersant exposure, especially since fisheries were not reopened until 

testing indicated that the waters were safe for fishing. Extensive seafood testing for PAHs and 

dispersant compounds found levels that were within the risk assessment protocol established by the 

U.S. Food and Drug Administration, NOAA, and the Gulf Coast States (Kang et al., 2012; Dickey, 

2012). However, there has been some dispute within the scientific community over the validity of the 

risk assessment protocol that was used and concern that the levels of concern established by the 

protocol may have underestimated the risk from seafood contaminants among vulnerable 

populations such as pregnant women and children (Rotkin-Ellman et al., 2012; Rotkin-Ellman and 

Soloman, 2012). Many of these short-term studies reach conflicting conclusions about the physical 

health effects, but the psychological studies generally agree that there are negative short-term 

effects in the mental health of people most affected by the spill. BOEM will continue monitoring 

post-spill health research studies for cumulative effects.

Non-OCS Oil- and Gas-Related Impacts

Non-OCS oil- and gas-related impacts (described in 

Chapter 3.3.2) cover a wide range of potential impactproducing factors, including all human activities and natural

events and processes that are not related to OCS oil- and 

gas-related activities. Some of the human activities that may 

include people and communities include, but are not limited

to, the following: 

• State-based and onshore oil and gas activities;

• commercial/residential/agricultural development;

• urbanization; pollution;

• zoning ordinances;

• expansions to the Federal, State, and local highway systems;

• expansions to regional port facilities;

• demographic shifts;

• shifts on the national, State, and local levels;
4-478 Gulf of Mexico Multisale EIS

• military activities;

• government functions;

• educational systems;

• family support systems;

• public health;

• contraction or expansion of the tourism industry; 

• State renewable energy activities;

• river channelization; and

• dredging of waterways. 

State offshore oil and gas programs and onshore oil and gas activities pose the same 

potential issues as does the OCS Program, although since State leases are closer to land, their 

petroleum-related activities are generally viewed as having greater potential for directly impacting 

coastal communities. BOEM assumes that sitings of any future facilities associated with State

programs would be based on the same economic, logistical, zoning, and permitting considerations 

that determined past sitings. Revenues from oil programs in State waters have produced several

positive impacts, and the steady stream of oil exploration and development have produced

positive cumulative impacts that include increased funding for infrastructure, higher incomes,

better health care, and improved educational facilities. This is certainly true for Texas, which has

historically used oil and gas revenues on State lands to equalize education district disparities across

the State. While offshore leasing in shallow waters has been in a general decline, Louisiana is 

attempting to incentivize increased activity closer to the shore. In 2006, the Louisiana 

Legislature authorized the Louisiana Dept. of Environmental Quality to implement an Expedited

Processing Program, which has so far resulted in a 55 percent reduction in coastal permitting time 

(State of Louisiana, Dept. of Natural Resources, 2009).

Ongoing for decades, urbanization continues to impact people and communities, involving 

demographic shifts as people move into or out of the more densely populated areas. Impacts that 

result include strains on public infrastructure, habitat fragmentation, and reduced air and water 

quality, as well as the urban heat island effect. Closely related, but not limited to urban areas, are 

pollution impacts such as garbage dumping, air, light and noise pollution, and contaminated runoff, 

which also impact people and the communities in which they live. Chapter 4.1 discusses air quality

and Chapter 4.2 discusses water quality. Zoning ordinances and land development, whether 

residential, commercial, or agricultural, can have negative and positive impacts on people, 

depending on how they stand to benefit or not from various proposed projects. When highway 

systems (whether local, State, or Federal) and port facilities are expanded, there is a tradeoff 

between the benefits of expansion and the potential negative impact to the local environment, 

people, and communities.
Description of the Affected Environment and Impact Analysis 4-479

Economic conditions contribute to cumulative impacts on people and communities. When 

there is an economic downturn, some people lose their jobs and unemployment rises; people have 

less money to spend, causing a negative ripple effect through the local/regional/national economy as 

a result of direct, indirect, and induced economic impacts on communities. Military activities also 

contribute to cumulative impacts, whether through base closures that result in job losses or 

infrastructure expansion at military bases that may produce both positive (jobs) and negative (habitat 

loss) impacts.

Other human activities that also have cumulative impacts on Gulf Coast populations are

related to local, State, and Federal government functions, which are numerous and expansive. Two 

of the more crucial government responsibilities for basic community functioning involve municipal

waterworks and sewage systems. If these are not maintained in good condition with adequate

capacity, negative impacts to the residents and community result. Similarly, the status of a 

community’s educational system may be a positive or negative benefit to these populations,

depending on the quality of the educational facilities and infrastructure, the teacher-to-student

ratios, the standardized test scores, the amount and extent of busing across cities and towns, and 

the availability of special education services in the public schools (National Education 

Association, 2015; FSG Social Impact Consultants, 2011). Another very important non-OCS

oil- and gas-related impact-producing factor involves public health and family support services

systems, namely their availability, proximity, and quality (CommonHealth ACTION, 2015). Social

services such as public health clinics, mental health support, charity hospitals, addictive disorder

rehabilitation, foster care, head start programs, and family planning services are often hard to find in

rural areas, but these services may be more accessible in larger cities, towns, and urban areas.

Another important factor to consider is the contraction and expansion of the tourism

industry, which is very important to the economies of the Gulf of Mexico region. When there is

a contraction in the tourism sector, the negative impacts are felt by all, whether directly or indirectly. 

BOEM funded a study (Eastern Research Group, Inc., 2014a) that developed methodologies for 

estimating the scales of recreation and tourism in a particular area. This entailed defining which 

industries comprise recreation and tourism, as well as estimating the percent of each industry that 

supports tourism. For example, the hotel industry is primarily supported by tourists, while the 

restaurant industry is supported by both tourists and local residents. Chapter 4.13 provides a 

complete discussion of tourism as a part of recreational resources. State renewable energy 

programs are non-OCS oil- and gas-related and may also contribute to cumulative impacts due to

their potential placement in areas that conflict with local uses, such as preferred fishing grounds. 

River channelization and dredging of other waterways also contribute to cumulative impacts for local 

populations, especially low- income and minority populations who may have traditionally fished and 

tended oyster beds negatively impacted by the disruption of the natural balance of the delicate 

ecosystem.

While human activities are extensive and nearly all-encompassing, there are many natural

events and processes that may be classified as non-OCS oil- and gas-related impact-producing 
4-480 Gulf of Mexico Multisale EIS

factors. Some of the natural events and processes that coastal populations may be affected by 

include, but are not limited to, the following: 

• oyster reef degradation; 

• saltwater intrusion; 

• sedimentation of rivers;

• sediment deprivation;

• barrier island migration and erosion; 

• fish kills;

• red tide;

• coastal erosion/subsidence;

• sea-level rise;

• coastal storms; and

• climate change.

When degradation of oyster reefs occurs, it may negatively impact people and 

communities, especially minority and low-income populations, by decreasing the number of oysters 

that are able to harvest for both economic and subsistence uses. Saltwater intrusion affects oyster

reefs and the overall wetlands ecosystem. In some places too much sediment is deposited in 

waterways, and in others there is sediment deprivation; both of these negatively impact the delicate

ecosystem upon which coastal populations depend. Barrier islands are very important for fishing, 

but the barrier islands in the region have been migrating and eroding for decades. This natural

process is one of the challenges faced in the region and contributes to cumulative impacts. Also, 

fish kills and red tide interfere with people’s use and enjoyment of the natural environment and 

contribute to negative cumulative impacts on GOM coastal populations.

Coastal erosion and subsidence in some parts of the southeastern coastal plain amplify the 

vulnerability of communities, infrastructure, and natural resources to storm-surge flooding (Dalton 

and Jones, 2010). Submergence in the GOM area is occurring most rapidly along the Louisiana 

coast and more slowly in other coastal states. Depending on local geologic conditions, the 

subsidence rate varies across coastal Louisiana from 3 to over 10 mm/yr (0.12 to over 0.39 in/yr). 

Natural drainage patterns along many areas of the Gulf Coast areas have been severely altered

by construction of the Gulf Intracoastal Waterway and other channelization projects associated

with its development. Saltwater intrusion resulting from land loss, river channelization, and canal

dredging is a major cause of coastal habitat deterioration (Tiner, 1984; National Wetlands 

Inventory Group, 1985; Cox et al., 1997). Coastal erosion, subsidence, sea-level rise, and storm 

surge damage can increase community vulnerability to future hazards and can also threaten

traditional ways of life. Saltwater intrusion reduces the productivity and species diversity
Description of the Affected Environment and Impact Analysis 4-481

associated with wetlands and coastal marshes (Stutzenbaker and Weller, 1989; Cox et al., 1997). 

While users of coastal waters may appear to trend towards the relatively affluent, low-income and 

minority groups may be more dependent on the resources of the Gulf Coast. Several ethnic

minority and low-income groups rely substantially on these resources (e.g., refer to Hemmerling and 

Colten [2003] for an evaluation of environmental justice considerations for south Lafourche Parish).

Coastal land loss from erosion, subsidence, sea-level rise, and storm surge also affect the 

larger society as a whole, with significant land loss occurring in coastal areas, especially Louisiana, 

which has created a Coastal Master Plan focused on resolving the land loss crisis (State of 

Louisiana, Coastal Protection and Restoration Authority, 2012). This affects people and 

communities by impacting residential areas as well as local businesses and public infrastructure. 

Figure 4-29 shows the amount of land that coastal Louisiana has lost from 1932 to 2010. Produced 

for Louisiana’s Coastal Master Plan (2012), Figuref 4-30 and 4-31 illustrate scientists’ projections 

for future land loss in Louisiana. The moderate projection (Figure 4-30) assumes more mitigating 

measures, and the less optimistic projection (Figure 4-31) shows the projected impact if extensive 

mitigating measures are not instituted. As evident from these visual depictions, coastal land loss is 

one of the greatest threats to the stability and future of coastal populations. The Louisiana’s 2012 

Coastal Master Plan captures the urgency of the land loss crisis: “Every day Louisiana citizens are 

affected by this catastrophe in ways small and large. Whether it’s a family forced to leave a 

cherished community to move out of harm’s way, a local businesses that has trouble obtaining 

insurance, or investments that lose value because of uncertainty about the future of our landscape, 

Louisiana’s land loss disaster takes a heavy toll” (State of Louisiana, Coastal Protection and 

Restoration Authority, 2012). Chapter 4.3.1 provides a detailed discussion of coastal land loss. A 

U.S. Geological Survey study published in 2013, Economic Vulnerability to Sea-Level Rise along the 

Northern U.S. Gulf Coast, applied a coastal economic vulnerability index (CEVI) to the northern Gulf 

coastal region in order to measure economic vulnerability to sea-level rise (Thatcher et al., 2013). 

The study attempted to determine which coastal communities may face the greatest challenges with 

regard to the economic and physical impacts of relative sea-level rise and revealed areas along the 

Gulf Coast that could most benefit from long-term resiliency planning. Within an area, the presence 

of a concentration of economically valuable infrastructure combined with physical vulnerability to 

inundation from sea-level rise resulted in the highest vulnerability rankings (CEVI score). The 

highest average CEVI score in the GOM coastal region appeared in Lafourche Parish, Louisiana, 

where there is an extensive amount of valuable infrastructure related to the oil and gas industry, 

along with high relative sea-level rise rates and high coastal erosion rates. Terrebonne Parish, 

Louisiana, also received a high CEVI value because of its high level of physical vulnerability and high 

concentration of energy infrastructure. Due to limitations within the CEVI model, such as subjective 

weighting of variables, researchers caution that results of the study should remain within a 

vulnerability context and that CEVI results should only be considered relative measures that are 

best utilized to provide decisionmakers with a better understanding of the vulnerability of the 

coastal region’s critical infrastructure when making decisions about modifying, protecting, or 

building new infrastructure in these coastal communities (Thatcher et al., 2013). Critical coastal 

infrastructure also bears the threat of extentive storm surge generated by hurricanes and tropical 

storms.
4-482 Gulf of Mexico Multisale EIS

Hurricanes, tropical storms, and other wind-driven tidal or storm events are a fact of life for 

communities living along the Gulf of Mexico coastal zone. The intensity and frequency of 

hurricanes in the GOM over the last several years has greatly impacted the system of protective 

barrier islands, beaches, and dunes and associated wetlands along the Gulf Coast. Within the last

several years, the Gulf Coast of Texas, Louisiana, Mississippi, Alabama, and to some degree 

Florida have experienced five major hurricanes (Ivan, Katrina, Rita, Gustav, and Ike), as well as

minor hurricanes (Humberto and Isaac). According to a U.S. Geological Survey 5-year,

post-Katrina survey, the wetland loss in Louisiana from all four storms (i.e., Hurricanes Katrina,

Rita, Gustav, and Ike) totaled 340 mi2

 (881 km2). The U.S. Geological Survey projects that

coastal Louisiana has undergone a net change in land area of about 1,883 mi2

 (4,877 km2) from 

1932 to 2010 (Couvillion et al., 2011). Impacts from future hurricanes and tropical storm events

are uncertain. Hazard mitigation funds available through individual states and the Federal 

Emergency Management Agency also seek to mitigate potential damage to homes in flood zones

throughout the GOM. While hurricanes and tropical storms are inevitable, lessons learned from 

Hurricanes Katrina, Rita, Gustav, and Ike are shaping local and national policies, as well as

nongovernmental organizations efforts to protect vulnerable communities. In the decade since 

Hurricanes Katrina and Rita, the New Orleans Metro Area has been recovering gradually, but 

unevenly. Population before the 2005 storms was 1.386 million, dropped to 1.040 million in 2006, 

and increased to 1.252 million in 2014. The number of grocery stores, pharmacies, and drug stores 

is still lower than 2005 numbers, but the number of gasoline stations, hotels, and restaurants have 

increased to greater than pre-storm levels (USDOC, Census Bureau, 2015f; USDOC, Economics 

and Statistics Administration, 2015).

Within the last few decades, climate change has become recognized as a serious issue. A 

study conducted by Petkova et al. (2015) focused on the impacts of climate change on the U.S. Gulf 

Coast and public health. The study found that numerous variables have contributed to the likelihood 

of extreme climate change impacts to the Gulf coastal region, including subsidence, severe erosion, 

changing water-use patterns, sea-level rise, storm surge, potential for large-scale industrial 

accidents, increasing population, and large numbers of vulnerable populations in the region. Climate 

change impacts may exacerbate existing public health issues and also create new health hazards. 

Identified climate change impacts include heat-related morbidity/mortality, drought-related 

malnutrition, flood-related injuries and death, increases in vector-borne diseases, and large-scale 

migrations. The study suggests various public health adaptation measures such as the creation of 

educational programs and improved risk communication for vulnerable persons such as the elderly, 

minority, and low-income populations (Petkova et al., 2015).

4.14.3.2.4 Incomplete or Unavailable Information

BOEM has identified unavailable information that is relevant to people and communities 

regarding the impacts of the Deepwater Horizon explosion, oil spill, and response. This information 

cannot be obtained because long-term health impact studies, subsistence studies, and the NRDA

process are ongoing, and data from these efforts would be unavailable and unobtainable for some 

time. In order to fill this data gap, BOEM has used existing information and reasonably accepted 
Description of the Affected Environment and Impact Analysis 4-483

scientific methodologies to extrapolate from available information in completing the relevant analysis, 

including information that has been released after the Deepwater Horizon explosion, oil spill, and 

response and studies of past oil spills, which indicate that a low-probability, catastrophic oil spill, 

which is not part of a proposed lease sale and not likely expected to occur, may have adverse 

impacts on residents in GOM coastal communities. Research into possible long-term health impacts 

of the Deepwater Horizon explosion, oil spill, and response continues (National Institute of 

Environmental Health Science, 2014; National Center for Disease Preparedness, 2013 and 2014; 

Substance Abuse and Mental Health Services Administration and Centers for Disease Control and 

Prevention, 2013). Because long-term health impacts to coastal populations are unknown, this 

information may be relevant to the evaluation of impacts from the Deepwater Horizon explosion, oil 

spill, and response; therefore, BOEM would continue to seek additional information as it becomes 

available and bases the previous analysis on the best information currently available. Although longterm health impacts to people and communities may be relevant to this analysis, BOEM has 

determined that the unavailable information is not essential to a reasoned choice among alternatives 

based on the information discussed above.

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

The potential impacts resulting from the industry’s routine activities occur within the larger 

socioeconomic context of the GOM region. Given the existing, extensive, and widespread support 

system for the OCS oil- and gas-related industry and its associated labor force, the impacts of 

routine events related to a proposed lease sale are expected to be negligible, widely distributed, 

and to have little impact. Routine activities related to a single lease sale would be incremental in 

nature, not expected to change existing conditions, and positive in their contribution to the 

sustainability of current industry, related support services, and associated employment. 

With the exception of a catastrophic accidental event, such as the Deepwater Horizon

explosion, oil spill, and response (which is not reasonably foreseeable and not part of a proposed 

action), the impacts of oil spills, chemical/drilling-fluid spills, vessel collision, and spill-response 

activities are not or are not likely to be of sufficient scale or duration to have adverse and 

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

Coastal populations experience cumulative impacts that include all human activities and 

natural processes and events. The cumulative analysis includes impacts that could result from a 

proposed lease sale combined with baseline conditions, all past, present, and future Federal OCS 

oil- and gas-related lease sales and activities, as well as all past, present, and reasonably 

foreseeable future actions that are external to Federal OCS oil- and gas-related activities. Within 

this divided analytical framework of OCS oil-and gas-related and non-OCS oil- and gas-related 

impacts, the largest quantity, by far, of impact-producing factors for coastal populations occur as 

non-OCS oil- and gas-related impacts because OCS oil- and gas-related activities form a very small 

part of the greater, complex socioeconomic structure in the GOM.
4-484 Gulf of Mexico Multisale EIS

4.14.3.2.6 Alternative B—Regionwide OCS Lease Sale Excluding Available Unleased Blocks 

in the WPA Portion of the Proposed Lease Sale Area

Impacts for social factors are directly related to the level of OCS oil- and gas-related activity 

in the Gulf of Mexico. Alternative B would result in less OCS oil- and gas-related activity than 

Alternative A because the WPA (approximately 23 million ac) would not be available for leasing. 

Alternative A includes the WPA, CPA, and EPA. Alternative B includes the CPA and EPA. 

Therefore, Alternative B would produce proportionately smaller OCS oil- and gas-related activity 

than Alternative A, and the impacts of Alternative B would be proportionately less than Alternative A 

but greater than Alternative C, as described below.

4.14.3.2.7 Alternative C—Regionwide OCS Proposed Lease Sale Excluding Available 

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

Impacts for social factors are directly related to the level of OCS oil- and gas-related activity 

in the Gulf of Mexico. Alternative C would result in less OCS oil- and gas-related activity than 

Alternative A or B because the CPA and EPA (approximately 49 million ac) would not be available 

for leasing. Alternative A includes the WPA, CPA, and EPA, and Alternative B includes the CPA and 

EPA. In contrast, Alternative C includes only the WPA. Therefore, Alternative C would produce 

proportionately smaller OCS oil- and gas-related activity than Alternatives A and B, and the impacts 

of Alternative C would be proportionately less than either Alternative A or B.

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

Unleased Blocks Subject to the Topographic Features, Live Bottom (Pinnacle 

Trend), and/or Blocks South of Baldwin County, Alabama, Stipulations

Impacts for social factors are directly related to the level of OCS oil- and gas-related activity 

in the Gulf of Mexico. Alternative D would have minimal impact on social factors because there are 

so few unleased blocks subject to the Topographic Features, Live Bottom (Pinnacle Trend), and/or 

Blocks South of Baldwin County, Alabama, Stipulations. The difference between Alternatives A, B, 

and C, with and without the exclusionary stipulations is negligible for social factors. The impacts 

under Alternative D would not be much different and likely not even measurable when compared 

with the other alternatives. To the extent that Alternative D would generate less OCS oil- and gasrelated activities due to the reduced number of blocks available for lease, the impacts of Alternative 

D would be less than Alternative A, B or C, but this difference would likely be indiscernible.

4.14.3.2.9 Alternative E—No Action

Alternative E would result in no lease sale and, thus, no incremental contribution of impacts 

to social factors beyond a potential negligible to minor negative economic impact on jobs because a 

single lease sale only contributes to the maintenance of existing employment. Any potential 

negative impact would be short lived and may not even be measurable.
Description of the Affected Environment and Impact Analysis 4-485

4.14.3.3 Environmental Justice Determination

Executive Order 12898, “Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations,” directs Federal agencies to make a determination as to

whether their actions have disproportionate environmental impacts on minority or low- income

people. These environmental impacts encompass human health, and social and economic 

consequences. In 1997, President Clinton issued Executive Order 13045, “Protection of Children 

from Environmental Health Risks and Safety Risks,” directing Federal agencies to identify and 

assess environmental health risks and safety risks of its policies, programs, and activities that

may disproportionately affect children. In accordance with NEPA and the Executive Orders,

BOEM provides opportunities for community input during the NEPA process.

One example of BOEM’s efforts to foster an inclusive and transparent public process are the 

meetings BOEM has held with the Vietnamese fisherfolk community in Mississippi. BOEM has 

provided Vietnamese translations of relevant portions of this Multisale EIS to maximize participation. 

Additional avenues of public outreach employed by BOEM include specific types of notices that are 

(1) mailed to public libraries; interest groups; industry; ports and docks; local, State, and Federal 

agencies; and federally recognized Indian Tribes; (2) published in local newspapers; (3) posted on 

the Internet; and (4) published in the Federal Register. The formal scoping process is initiated by 

the publication of a Notice of Intent, and public scoping meetings are held in several geographically 

separate cities to allow the public to submit comments and to identify all stakeholders’ concerns. All 

public comments and responses to comments are published in the Draft and Final Supplemental 

EISs. A detailed discussion of the complete scoping process can be found in Chapter 5.3. A 

summary of the scoping comments for this Multisale EIS can be found in Chapter 5.3.1. 

In accordance with 40 CFR §§ 1508.7 and 1508.8, BOEM has considered potential 

cumulative, direct, and indirect impacts to minority and low-income populations in the analysis area. 

Furthermore, in reaching this considered environmental justice determination, BOEM utilized 

guidance from CEQ (1997), USEPA (1998), and the Federal Interagency Working Group on 

Environmental Justice & NEPA Committee (2016). The OCS lease sales occur in Federal waters 

9 nmi (10.36 mi; 16.67 km) offshore Texas and Florida, and 3 nmi (3.5 mi; 536 km) offshore 

Louisiana, Mississippi, and Alabama. Thus, the permitted activities of petroleum exploration, 

extraction, and production that occur on these leaseholds are distant from human habitation, and 

these activities would not have any direct impacts on low-income and minority populations. State

offshore oil and gas leasing occurs in waters closer to land were petroleum-related activities are

generally viewed as having a greater potential for directly impacting coastal communities. 

Indirect impacts to minority and low-income populations would occur onshore and would result from 

the operations of the extensive infrastructure system that supports all onshore and offshore oil and 

gas activities. This downstream infrastructure moves hydrocarbon product to market and includes

gas processing facilities, petrochemical plants, transportation corridors, petroleum bulk storage 

facilities, and gas and petroleum pipelines. These components comprise a mature, widespread, and 

concentrated infrastructure system (refer to Chapter 4.14.1). Much infrastructure is located in

coastal Louisiana and Texas, and to a lesser extent in Mississippi’s Jackson County and 
4-486 Gulf of Mexico Multisale EIS

Alabama’s Mobile County. While many fabrication and supply facilities are concentrated around 

coastal ports, downstream processing is concentrated in industrial corridors farther inland 

(Dismukes, 2011; Kaplan et al., 2011). The onshore downstream infrastructure exists to support all 

oil- and gas-related activities regardless of source (onshore, offshore and imported product). The 

proportion of Federal OCS contribution to downstream infrastructure use has not yet and, most 

likely, may never be possible to determine as it is dependent on highly unpredictable maket 

demands and prices. Potential environmental justice impacts that may arise from downstream

support activities cannot be influenced by BOEM’s decisionmaking because BOEM has no 

regulatory authority over any onshore activities, including their location. Many other Federal and 

State agencies regulate onshore oil- and gas-related infrastructure through air and wastewater 

discharge permitting and stream and wetland permitting. Through these permitting processes, the 

Federal agencies are required to consider environmental justice impacts for their proposed Federal 

actions. Therefore, BOEM has determined that a proposed lease sale would not adversely affect 

minority and low-income populations.

4.15 UNAVOIDABLE ADVERSE IMPACTS OF A PROPOSED ACTION

Unavoidable adverse impacts associated with a proposed action are expected to be primarily 

short term and localized in nature and are summarized below. Adverse impacts from low-probability 

catastrophic events, which are not part of a proposed action and not likely expected to occur, could 

be of longer duration and extend beyond the local area. All OCS oil- and gas-related activities 

involve temporary and exclusive use of relatively small areas of the OCS over the lifetimes of 

specific projects. Lifetimes for these activities can be days, as in the case of seismic surveys, or 

decades, as in the case of a production structure or platform. No activities in the OCS Program 

involve the permanent or temporary use or “taking” of large areas of the OCS. Cumulatively, 

however, a multitude of individual projects results in a major use of OCS space.

Air Quality: Unavoidable short-term impacts on air quality could occur after large oil spills

because of evaporation and volatilization of the lighter components of crude oil, combustion from 

surface burning, and aerial spraying of dispersant chemicals. Mitigation of long-term impacts from 

offshore engine combustion during routine operations would be accomplished through existing 

regulations and the development of new control emission technology. Short-term impacts from spill 

events could occur and are likely to be aggravated or mitigated by the time of year the spills take 

place.

Water Quality: Routine offshore operations would cause some unavoidable adverse impacts 

to varying degrees on the quality of the surrounding water. Drilling, construction, overboard 

discharges of drilling mud and cuttings, and pipelaying activities would cause an increase in the 

turbidity of the affected waters for the duration of the activity periods. This, however, would only 

affect water in the immediate vicinity of the construction activity or in the vicinity of offshore 

structures, rigs, and platforms. Mitigation of impacts from these activities would be accomplished 

through existing NPDES regulations. Accidental spills from platforms and the discharge of produced 

waters could result in increases of hydrocarbon levels and trace metal concentrations in the water 
Description of the Affected Environment and Impact Analysis 4-487

column in the vicinity of the platforms. Spilled oil from a tanker collision would affect the water 

surface in combination with dispersant chemicals used during spill response. A subsurface spill 

would subject the surface, water column, and near-bottom environment to spilled oil and gas 

released from solution, dispersant chemicals, or emulsions of dispersed oil droplets and dispersant 

chemicals.

Unavoidable impacts to onshore water quality would occur as a result of chronic point- and 

nonpoint-source discharges such as runoff and effluent discharges from existing onshore 

infrastructure used in support of lease sale activities. Vessel traffic contributes to the degradation of 

water quality by chronic low-quantity oil leakage, treated sanitary and domestic waste, bilge water, 

and contaminants known to exist in ship paints. Regulatory requirements of the State and Federal 

water authorities and some local jurisdictions would be applicable to point-source discharges from 

support facilities such as refineries and marine terminals.

Coastal Habitats: If an oil spill contacts beaches or barrier islands, the removal of beach 

sand during cleanup activities could result in adverse impacts if the sand is not replaced, and a 

beach could experience several years of small surface residue balls (also called tarballs) washing 

ashore over time, causing an aesthetic impact. Sand borrowing on the OCS for coastal restorations 

involves the taking of a quantity of sand from the OCS and depositing it onshore, essentially moving 

small products of the deltaic system to another location. If sand is left where it is, it would eventually 

be lost to the deltaic system by redeposition or burial by younger sediments; if transported onshore, 

it would be lost to burial and submergence caused by subsidence and sea-level rise.

If an oil spill contacts coastal wetlands, adverse impacts could be high in localized areas. In 

more heavily oiled areas, wetland vegetation could experience suppressed productivity for several 

years; in more lightly oiled areas, wetland vegetation could experience die-back for one season. 

Epibionts (organisms growing) on wetland vegetation and grasses in the tidal zone could be killed, 

and the productivity of tidal marshes for the vertebrates and invertebrates that use them to spawn 

and develop could be impaired. Much of the wetland vegetation would recover over time, but some 

wetland areas could be converted to open water. Some unavoidable impacts could occur during 

pipeline and other related coastal construction, but regulations are in place to avoid and minimize 

these impacts to the maximum extent practicable. Unavoidable impacts resulting from dredging, 

wake erosion, and other secondary impacts related to channel use and maintenance would occur as 

a result of a proposed action.

Offshore Biological Habitats: Unavoidable adverse impacts would take place if an oil spill

occurred and contacted offshore biological habitats, such as Sargassum at the surface; fish, turtles, 

and marine mammals in the water column; or benthic habitats on the bottom. There could be some 

adverse impacts on organisms contacted by oil, dispersant chemicals, or emulsions of dispersed oil 

droplets and dispersant chemicals that, at this time, are not completely understood, particularly in 

subsurface environments.
4-488 Gulf of Mexico Multisale EIS

Fish and Invertebrate Resources: Unavoidable adverse impacts from routine operations 

would take place from discharges from vessels and platforms. These would be minor given the 

available area for fish habitat. If a large oil spill occurs, the oil, dispersant chemicals, or emulsions of 

oil droplets and dispersant chemicals could temporarily displace mobile fish species on a population 

or local scale. There could also be impacts on prey and sublethal impacts on fish.

Birds: Unavoidable adverse impacts from routine operations on birds could result from 

noise, helicopter and OCS service-vessel traffic, coastal facility and platform lighting, and floating 

trash and debris. Trans-Gulf migrating species could be affected by lighted platforms, helicopter and 

vessel traffic, and floating trash and debris. If a large oil spill occurs and contacts bird habitats, 

some birds could experience lethal and sublethal impacts from oiling, and birds feeding or resting in 

the water could be oiled and die. Birds coming into contact with oil may migrate more deeply into 

marsh habitats, out of reach from spill responders seeking to count them or collect them for 

rehabilitation. Oil spills and oil-spill cleanup activities could also affect the food species for bird 

species. Depending on the time of year, large oil spills could decrease the nesting success of 

species that concentrate nests in coastal environments due to direct impacts of the spill and also 

disruption from oil-spill cleanup activities.

Threatened and Endangered Species: Because a proposed lease sale does not in and of 

itself make any irreversible or irretrievable commitment of resources that would foreclose the 

development or implementation of any reasonable and prudent measures to comply with the 

Endangered Species Act, BOEM may proceed with publication of this Multisale EIS and finalize a 

decision among these alternatives even if consultation is not complete, as described in Section 7(d) 

of the ESA (also refer to Chapter 5.7). Irreversible loss of individuals that are ESA-listed species 

may occur after a large oil spill from the acute impact of being oiled or the chronic impact of oil 

having eliminated, reduced, or rendered suboptimal the food species upon which they were 

dependent.

Marine Mammals: Unavoidable adverse impacts to marine mammals would be those that 

also affect endangered and threatened marine mammal species. Routine operation impacts (such 

as seismic surveys, water quality and habitat degradation, helicopter disturbance, vessel collision, 

and discarded trash and debris) would be negligible or minor to a population, but they could be lethal 

to individuals as in the case of a vessel collision. A large oil spill would temporarily degrade habitat if 

spilled oil, dispersant chemicals, or emulsions of dispersed oil droplets and dispersant chemicals 

contact free-ranging pods or calving grounds.

Commercial Fisheries and Recreational Fishing: Unavoidable adverse impacts from routine 

operations are loss of open ocean or bottom areas desired for fishing by the presence or 

construction of OCS oil- and gas-related facilities and pipelines. Loss of gear could occur from 

bottom obstructions around platforms and subsea production systems. If a large oil spill occurs, it is 

unlikely that fishermen would want, or be permitted, to harvest fish in the area of an oil spill, as 

spilled oil could coat or contaminate commercial fish species, rendering them unmarketable.
Description of the Affected Environment and Impact Analysis 4-489

Recreational Resources: Unavoidable adverse impacts from routine operations may result in 

the accidental loss overboard of some floatable debris that may eventually come ashore on 

frequented recreational beaches. A large oil spill could make landfall on recreational resources, 

leading to local or regional economic losses and stigma effects, causing potential users to avoid the 

area after acute impacts have been removed. Some recreational resources become temporarily 

soiled by weathered crude oil, and small surface residue balls (also called tarballs) may come 

ashore long after stranded oil has been cleaned from shoreline areas. Impacts on recreational 

resources from a large oil spill may, at the time, seem irreversible, but the impacts are generally 

temporary. Beaches fouled by a large oil spill would be temporarily unavailable to the people who 

would otherwise frequent them, but only during the period between landfall and cleanup of the oil, 

followed by an indefinite lag period during which stigma effects recede from public consciousness.

Archaeological Resources: Unavoidable adverse impacts from routine operations could lead 

to the loss of unique or significant archaeological. It is BOEM’s policy to not approve any EP or 

DOCD plan with known or potential archaeological resources within 500 ft (152 m) of the planned 

activity or a pipeline application with known or potential archaeological resources within the pipeline 

corridor or right-of-way (the 200-ft [61-m] corridor in which the pipeline is to be constructed). For 

decommissioning activities, all known or potential (i.e., sidescan-sonar targets) archaeological 

resources must be investigated before site clearance activities take place, and if the presence of 

archaeological resources is confirmed, exceptions to the site clearance requirements at that location 

would be granted. Complete archaeological data recovery (excavation) would be required if BOEM 

decided that a permitted activity must take place that would cause an adverse impact to an 

archaeological resource.

Economic and Social Factors: Net economic, political, and social benefits to the U.S. accrue 

from the production of hydrocarbon resources. Once these benefits become routine, unavoidable 

adverse impacts from routine operations follow trends in supply and demand based on the 

commodity prices for oil, gas, and refined hydrocarbon products. Declines in oil and gas prices can 

lead to activity ramp downs by operators until prices rise. A large oil spill would cause temporary 

increases in economic activity associated with spill-response activity. An increase in economic 

activity from the response to a large spill could be offset by temporary work stoppages that are 

associated with spill-cause investigations and would involve a transfer or displacement of demand to 

different skill sets. Routine operations affected by new regulations that are incremental would not 

have much effect on the baseline of economic activity; however, temporary work stoppages or the 

introduction of several new requirements at one time, which are costly to implement, could cause a 

drop-off of activity as operators adjust to new expectations or use the opportunity to move resources 

to other basins where they have interests.

4.16 IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES

Irreversible or irretrievable commitment of resources refers to impacts or losses to resources 

that cannot be reversed or recovered. Examples are when a species becomes extinct or when 

wetlands are permanently converted to open water. In either case, the loss is permanent.
4-490 Gulf of Mexico Multisale EIS

4.16.1 Coastal Habitats

An irreversible or irretrievable loss of wetlands and associated biological resources could 

occur if wetlands are permanently lost because of impacts caused by dredging and construction 

activities that displace existing wetlands or from oil spills severe enough to cause permanent 

die-back of vegetation and conversion to open water. Construction and emplacement of onshore 

pipelines in coastal wetlands displace coastal wetlands in disturbed areas that are then subject to 

indirect impacts like saltwater intrusion or erosion of the marsh soils along navigation channels and 

canals. Regulatory requirements of the State and Federal water authorities and some local 

jurisdictions would be applicable to these activities to mitigate these impacts. Ongoing natural and 

anthropogenic processes in the coastal zone, only one of which is an OCS oil- and gas-related 

activity, can result in direct and indirect loss of wetlands. Natural losses as a consequence of the 

coastal area becoming hydrologically isolated from the Mississippi River that built it, sea-level rise, 

and subsidence of the delta platform in the absence of new sediment added to the delta plain appear 

to be much more dominant processes impacting coastal wetlands.

4.16.2 Biological Resources

An irreversible loss or degradation of ecological habitat caused by cumulative activity tends 

to be incremental over the short term. Irretrievable loss may not occur unless or until a critical 

threshold is reached. It can be difficult or impossible to identify when that threshold is, or would be, 

reached. Oil spills and chronic low-level pollution can injure and kill organisms at virtually all trophic 

levels. Mortality of individual organisms can be expected to occur, and possibly a reduction or even 

elimination of a few small or isolated populations. The proposed biological stipulations, however, are 

expected to eliminate most of these risks.

4.16.2.1 Threatened and Endangered Species

Irreversible loss of individuals that are protected species may occur after a large oil spill from 

the acute impact of being oiled or the chronic impact of oil having eliminated, reduced, or rendered 

suboptimal the food species upon which they were dependent.

4.16.2.2 Fish and Invertebrate Resources, Deepwater Benthic Communities, Commercial 

Fisheries, and Recreational Fishing

Irreversible loss of fish and invertebrate resources, including commercial and recreational 

species, are caused by structure removals using explosives. Fish in proximity to an underwater 

explosion can be killed. Without the structure to serve as habitat area, sessile, attached 

invertebrates and the fish that live among them are absent. Removing structures eliminates these 

special and local habitats and the organisms living there, including such valuable species as red 

snapper. Continued structure removal, regardless of the technique used, would reduce the net 

benefits to commercial fishing due to the presence of these structures. However, the Rigs-to-Reef 

Program would help offset these impacts.
Description of the Affected Environment and Impact Analysis 4-491

4.16.3 Archaeological Resources

Any loss of undiscovered archaeological resources on or below the seafloor of the OCS in 

developed areas would be an irreversible and irretrievable commitment of resources. A resource 

can be completely destroyed, severely damaged, or the scientific context badly impaired by well 

drilling, subsea completions, and platform and pipeline installation, or sand borrowing. An 

archaeological survey, avoidance through development design, documentation, and/or other 

mitigation would be accomplished prior to development, so as to minimize impacts.

4.16.4 Oil and Gas Development

Leasing and subsequent development and extraction of hydrocarbons as a result of a 

proposed action represents an irreversible and irretrievable commitment by the removal and 

consumption of nonrenewable oil and gas resources. The estimated amount of resources to be 

recovered as a result of a proposed action is presented in Chapter 3.1. 

4.16.5 Loss of Human and Animal Life

The OCS oil and gas exploration, development, production, and transportation are carried 

out under comprehensive, state-of-the-art, enforced regulatory procedures designed to ensure public 

and work place safety and environmental protection. Nevertheless, some loss of human and animal 

life may be inevitable from unpredictable and unexpected acts of man and nature (i.e., unavoidable 

accidents, accidents caused by human negligence or misinterpretation, human error, and adverse 

weather conditions). Some normal and required operations, such as structure removal, can kill sea 

life in proximity to explosive charges or by removal of the structure that served as the framework for 

invertebrates living on it and the fish that lived with it.

4.17 RELATIONSHIP BETWEEN THE SHORT-TERM USE OF MAN’S ENVIRONMENT AND 

THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY

The short-term impacts on various components of the environment in the vicinity of the 

proposed action are related to long-term impacts and the maintenance and enhancement of 

long-term productivity.

4.17.1 Short-Term Use

Short-term refers to the total duration of oil and gas exploration and production activities. 

Extraction and consumption of offshore oil and natural gas is a short-term benefit. Discovering and 

producing domestic oil and gas now reduces the Nation’s dependency on foreign imports. Depleting 

a nonrenewable resource now removes these domestic resources from being available for future 

use. The production of offshore oil and natural gas as a result of a proposed action would provide 

short-term energy, and as it delays the increase in the Nation’s dependency on foreign imports, it 

can also allow additional time for ramp-up and development of long-term renewable energy sources 

or substitutes for nonrenewable oil and gas. Economic, political, and social benefits would accrue 

from the availability of these natural resources.
4-492 Gulf of Mexico Multisale EIS

The principle short-term use of the leased areas in the Gulf of Mexico would be for the 

production of up to 0.211-1.118 BBO and 0.547-4.424 Tcf of gas from a proposed action. The 

cumulative impacts scenario in this Multisale EIS extends approximately from 2017 to 2066. The 

50-year time period is used because it is the approximate longest life span of activities conducted on 

an individual lease. The 50 years following a proposed lease sale is the period of time during which 

the activities and impacting factors that follow as a consequence of a proposed lease sale would be 

influencing the environment.

The specific impacts of a proposed action vary in kind, intensity, and duration according to 

the activities occurring at any given time (Chapter 3). Initial activities, such as seismic surveying 

and exploration drilling, result in short-term, localized impacts. Development drilling and well 

workovers occur sporadically throughout the life of a proposed action but also result in short-term, 

localized impacts. Activities during the production life of a platform may result in chronic impacts 

over a longer period of time (over 25 years), potentially punctuated by more severe impacts as a 

result of accidental events or a spill. Platform removal is also a short-term activity with localized 

impacts, including removal of the habitat for encrusting invertebrates and fish living among them. 

Many of the impacts on physical, biological, and socioeconomic resources discussed in Chapter 4

are considered to be short term (being greatest during the construction, exploration, and early 

production phases). These impacts would be further reduced by the mitigating measures discussed 

in Chapter 2.2.4. 

The OCS development off Texas and Louisiana has enhanced recreational and commercial 

fishing activities, which in turn has stimulated the manufacture and sale of larger private fishing 

vessels and specialized recreational fishing equipment. Commercial enterprises such as charter 

boats have become heavily dependent on offshore structures for satisfying recreational customers. 

A proposed action could increase these incidental benefits of offshore development. Offshore 

fishing and diving have gradually increased in the past three decades, with offshore structures and 

platforms becoming the focus of much of that activity. As mineral resources become depleted, 

platform removals would occur and may result in a decline in these activities, but this could be offset 

by the Rigs-to-Reef program.

The short-term exploitation of hydrocarbons for the OCS Program in the Gulf of Mexico may 

lead to long-term impacts on biologically sensitive resources and areas if a large oil spill occurs. A 

spill and spill-response activity could temporarily interfere with commercial and recreational fishing, 

beach use, and tourism in the area where the spill makes landfall and in a wider area based on 

stigma effects. The proposed leasing may also result in onshore development and population 

increases that could cause very short-term adverse impacts to local community infrastructure, 

particularly in areas of low population and minimal existing industrial infrastructure (refer to 

Chapter 4.14).
Description of the Affected Environment and Impact Analysis 4-493

4.17.2 Relationship to Long-Term Productivity

Long-term refers to an indefinite period beyond the termination of oil and gas production. 

Over a period of time after peak oil production has occurred in the Gulf of Mexico, a gradual easing 

of the specific impacts caused by oil and gas exploration and production would occur as the 

productive reservoirs in the Gulf have been discovered and produced, and have become depleted. 

The BSEE estimates that oil production in the GOM peaked at 1.6 MMbbl/day in 2002, declined for a 

few years and then peaked again in 2009 and 2010 at 1.6 MMbbl/day before declining again. 

Production rates in 2015 indicate that it was another high year (1.5 MMbbl/day), and gas production 

in the GOM peaked at 14.4 Bcf/day in 1997 and has declined since then to 3.6 Bcf/day in 2015 

(USDOI, BSEE, 2016). Production has shifted from many smaller reserves on the continental shelf 

to fewer larger reserves in deep water. Large deepwater oil discoveries have the potential to alter 

the oil production rate, but the exact effect any one discovery would have or when that discovery 

would be made is difficult to project due to the difficulties that may be encountered producing these 

prospects because of their geologic age; burial depth and high-temperature, high-pressure in-situ

conditions; lateral continuity of reservoirs; and the challenges of producing from ultra-deepwater 

water depths.

The Gulf of Mexico’s large marine ecosystem is considered a Class II, moderately productive 

ecosystem (mean phytoplankton primary production 150-300 gChlorophyll a/m2

-yr [The 

Encyclopedia of Earth, 2008]) based on Sea-viewing Wide Field-of-view Sensor (SeaWiFS) global 

primary productivity estimates (USDOC, NASA, 2003). After the completion of oil and gas 

production, a gradual ramp-down to economic conditions without OCS oil- and gas-related activity 

would be experienced, while the marine environment is generally expected to remain at or return to 

its normal long-term productivity levels that, in recent years, has been described as stressed (The 

Encyclopedia of Earth, 2008). The Gulf of Mexico’s large marine ecosystem shows signs of 

ecosystem stress in bays, estuaries, and coastal regions (Birkett and Rapport, 1999). There is 

shoreline alteration, pollutant discharge, oil and gas development, and nutrient loading. The overall 

condition for the U.S. section of this large marine ecosystem, according to the USEPA’s seven 

primary indicators (Jackson et al., 2000), is good dissolved oxygen, fair water quality, poor coastal 

wetlands, poor eutrophic condition, and poor sediment, benthos, and fish tissue (The Encyclopedia 

of Earth, 2008).

To help sustain the long-term productivity of the Gulf of Mexico ecosystem, the OCS 

Program provides structures to be used as site-specific artificial reefs and fish-attracting devices for 

the benefit of commercial and recreational fishermen and for sport divers and spear fishers. 

Approximately 10 percent of the oil and gas structures removed from the OCS are eventually used 

for State artificial reef programs. Additionally, the OCS Program continues to improve the 

knowledge and mitigation practices used in offshore development to enhance the safe and 

environmentally responsible development of OCS oil and gas resources.

CHAPTER 5 

CONSULTATION AND COORDINATION

Consultation and Coordination 5-3 

What’s in This Chapter?

• BOEM is undertaking consultation and other activities to comply with laws and Executive 

Orders.

• BOEM coordinated the prelease process with key agencies and organizations.

• The prelease and NEPA process has included the following to date: publication of the 

Notice of Intent to Prepare an EIS (NOI); the Call for Information (Call); and the Area 

Identification (Area ID) memorandum.

• BOEM conducted internal and public scoping to determine the content of this Multisale

EIS.

• The USEPA (Regions 4 and 6) is a cooperating agency on this Multisale EIS. 

• BOEM solicited comments on the Draft Multisale EIS from April 22-June 7, 2016.

• Several changes were made between the Draft and Final Multisale EISs; these changes

were the result of new information becoming available, editorial suggestions, and 

comments received on the Draft Multisale EIS.

5 CONSULTATION AND COORDINATION

5.0 INTRODUCTION

BOEM is undertaking consultation and other activities to comply with the following laws, 

including but not limited to, the following: the development of consistency determinations (CDs)

under the Coastal Zone Management Act (CZMA); consultation under the Endangered Species Act 

(ESA) for potential impacts to listed species or designated critical habitat; completion of an Essential 

Fish Habitat assessment pursuant to the Magnuson-Stevens Fishery Conservation and 

Management Act; and a request for comments and consultation with federally recognized Indian 

Tribes pursuant to the National Historic Preservation Act and Executive Order 13175. Pursuant to 

NEPA, BOEM has conducted numerous public involvement activities during scoping for and review 

of the Draft Multisale EIS. This chapter describes the processes with which BOEM worked with 

other Federal and State agencies, Tribal governments, and the public during the development of the 

this Multisale EIS.

5.1 COASTAL ZONE MANAGEMENT ACT

The Federal agency performs a consistency review pursuant to the CZMA, and CDs are 

prepared for each coastal State along the Gulf of Mexico with a federally approved Coastal 

Management Program (CMP) prior to each of the proposed lease sales. To prepare the CDs, 

BOEM reviews each State’s approved Coastal Management Plan and analyzes the potential impacts 

as outlined in this Multisale EIS, new information, and applicable studies as they pertain to the 

enforceable policies of each CMP. The CZMA requires that Federal actions that have reasonably 

foreseeable coastal effects (i.e., effects to any coastal use or resource of the coastal zone) be 

“consistent to the maximum extent practicable” with relevant enforceable policies or guidelines of the 

State’s federally approved coastal management program (15 CFR part 930 subpart C).

Based on these and other analyses, BOEM’s Gulf of Mexico OCS Region’s Regional 

Director makes an assessment of consistency, which is then sent to the States of Texas, Louisiana, 
5-4 Gulf of Mexico Multisale EIS

Mississippi, Alabama, and Florida for proposed regionwide lease sales; to Texas and Louisiana for 

proposed WPA lease sales; or Louisiana, Mississippi, Alabama, and Florida for proposed CPA 

and/or EPA lease sales. If the State concurs, BOEM can proceed with the proposed lease sale. A 

State’s concurrence may be presumed when a State does not provide a response within the 60-day 

review period. A State may request an extension of time to review the CD within the 60-day period, 

which the Federal agency shall approve for an extension of 15 days or less. If a State objects, it 

must do the following under the CZMA:

(1) indicate how BOEM’s prelease proposal is inconsistent with the State’s federally

approved CMP and suggest alternative measures to bring BOEM’s proposal 

into consistency with the State’s CMP; or

(2) describe the need for additional information that would allow a determination of 

consistency. In the event of an objection, the Federal and State agencies 

should use the remaining portion of the 90-day review period to attempt to 

resolve their differences (15 CFR § 930.43(b)).

At the end of the 90-day review period, the Federal agency shall not proceed with the activity 

over a State agency’s objection unless the Federal agency concludes that, under the “consistent to 

the maximum extent practicable” standard described in 15 CFR § 930.32, consistency with the 

enforceable policies of the CMP is prohibited by existing law applicable to the Federal agency and 

the Federal agency has clearly described, in writing, to the CZMA State agency the legal 

impediments to full consistency; or, the Federal agency has concluded that its proposed action is 

fully consistent with the enforceable policies of the CMP, though the State agency objects. Unlike 

the consistency process for specific OCS plans and permits, there is no procedure for administrative 

appeal to the Secretary of Commerce for a Federal CD for prelease activities. In the event that there 

is a serious disagreement between BOEM and a State, either agency may request mediation. 

Mediation is voluntary, and the Secretary of Commerce would serve as the mediator. Whether there 

is mediation or not, the final CD is made by DOI, and it is the final administrative action for the 

prelease consistency process. Each Gulf State’s CMP is described in Appendix J. 

5.2 ENDANGERED SPECIES ACT

The Endangered Species Act of 1973 (16 U.S.C. §§ 1531 et seq.) establishes a national 

policy designed to protect and conserve threatened and endangered species and the ecosystems 

upon which they depend. BOEM and BSEE are currently in consultation with NMFS and FWS 

regarding the OCS oil and gas program in the Gulf of Mexico. BOEM is acting as the lead agency in 

the ongoing consultation, with BSEE’s assistance and involvement. The programmatic consultation 

was expanded in scope after reinitiation of consultation by BOEM in 2010 following the Deepwater 

Horizon explosion and oil spill, and it will include both existing and future OCS oil and gas leases in 

the Gulf of Mexico over a 10-year period. This consultation also considers any changes in baseline 

environmental conditions following the Deepwater Horizon explosion, oil spill, and response. The 

programmatic consultation includes postlease activities associated with OCS oil- and gas-related 

activities in the Gulf of Mexico, as well as G&G and decommissioning activities. While the 
Consultation and Coordination 5-5 

programmatic Biological Opinion is in development, BOEM and NMFS have agreed to interim 

consultations on postlease approvals. BOEM has received a draft Biological Opinion from FWS and 

is currently reviewing it. BOEM is awaiting a Biological Opinion from NMFS.

With consultation ongoing, BOEM and BSEE will continue to comply with all reasonable and 

prudent measures and the terms and conditions under the existing consultations, along with 

implementing the current BOEM- and BSEE-required mitigation, monitoring, and reporting 

requirements. Based on the most recent and best available information at the time, BOEM and 

BSEE will also continue to closely evaluate and assess risks to listed species and designated critical 

habitat in upcoming environmental compliance documentation under NEPA and other statutes. 

Refer to Appendix K for copies of the consultation letters.

5.3 MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT ACT

Pursuant to Section 305(b) of the Magnuson-Stevens Fishery Conservation and 

Management Act, Federal agencies are required to consult with NMFS on any action that may result 

in adverse effects to EFH. The NMFS published the final rule implementing the EFH provisions of 

the Magnuson-Stevens Fisheries Conservation and Management Act (50 CFR part 600) on 

January 17, 2002. Certain OCS oil- and gas-related activities authorized by BOEM may result in 

adverse effects to EFH and therefore require EFH consultation.

BOEM prepared a 2017-2022 EFH Assessment on behalf of BOEM and BSEE; it describes 

the Gulf of Mexico OCS Region’s OCS proposed activities, analyzes the effects of the proposed 

activities on EFH, and identifies proposed mitigating measures (USDOI, BOEM, 2016d). This 

Assessment was sent to NMFS on June 8, 2016, with a letter requesting formal consultation. This 

regional programmatic EFH consultation will cover the proposed Gulf of Mexico lease sales 

analyzed in the Five-Year Program and the related activities (i.e., decommissioning and geological 

and geophysical). The EFH Assessment, the formalized conservation, and the recommendations 

put forth by NMFS and accepted by BOEM/BSEE or NMFS’ concurrence will complete the EFH

consultation. However, all agencies will continue to communicate for the duration of the EFH

consultation (2017-2022).

5.4 NATIONAL HISTORIC PRESERVATION ACT

In accordance with the National Historic Preservation Act (54 U.S.C. §§ 300101 et seq.), 

Federal agencies are required to consider the effects of their undertakings on historic properties. 

The implementing regulations for Section 106 of the National Historic Preservation Act, issued by the 

Advisory Council on Historic Preservation (36 CFR part 800), specify the required review process. 

In accordance with 36 CFR § 800.8(c), BOEM intends to use the NEPA substitution process and 

documentation for preparing a prelease EIS and Record of Decision or a postlease environmental 

assessment and Finding of No Significant Impact to comply with Section 106 of the National Historic 

Preservation Act in lieu of 36 CFR §§ 800.3-800.6. Because of the extensive geographic area 

analyzed in this Multisale EIS and because identification of historic properties will take place after 

leases are issued, BOEM will complete its Section 106 review process once BOEM has performed 
5-6 Gulf of Mexico Multisale EIS

the necessary site-specific analysis of postlease activities prior to issuing a permit or approving 

these activities. Additional consultations with the Advisory Council on Historic Places, State Historic 

Preservation Offices, federally recognized Indian Tribes, and other consulting parties may take place 

at that time, if appropriate. Refer to Chapter 4.13 for more information on this review process and 

Appendix K for copies of the State Historic Preservation Offices’ concurrence letters. 

As an early planning effort, BOEM initiated a request for comment on the NOI for the 

Multisale EIS via a formal letter to each of the affected Gulf Coast States on April 3, 2015. A 30-day 

comment period was provided. The State Historic Preservation Officers for Alabama, Florida, and 

Louisiana responded via formal letters, all concurring that no historic properties will be affected. The 

Florida State Historic Preservation Officer further requested to be notified and given the opportunity 

to comment should any cultural resources be identified off the Florida coast. No additional 

responses were received.

BOEM also solicited Tribal comment on the 2017-2022 Outer Continental Shelf Oil and Gas 

Leasing: Draft Proposed Program via a formal letter on March 4, 2015, and on the Gulf of Mexico 

OCS Oil and Gas Lease Sales: 2017-2022; Gulf of Mexico Lease Sales 249, 250, 251, 252, 253, 

254, 256, 257, 259, and 261—Draft Environmental Impact Statement via a formal letter on May 19, 

2016. Those letters were addressed to each of the Gulf Coast State-affiliated federally recognized 

Indian Tribes, including the Alabama-Coushatta Tribe of Texas, Caddo Nation of Oklahoma, 

Chitimacha Tribe of Louisiana, Choctaw Nation of Oklahoma, Coushatta Tribe of Louisiana, Jena 

Band of Choctaw Indians, Miccosukee Tribe of Indians of Florida, Mississippi Band of Choctaw 

Indians, Poarch Band of Creek Indians, Seminole Tribe of Florida, Seminole Nation of Oklahoma, 

and Tunica-Biloxi Indian Tribe of Louisiana. The May 2016 letter was also sent to the Muscogee 

(Creek) Nation. No comments or requests to consult have yet been received; however, BOEM 

continues to invite Tribal consultation on all of its activities and will be responsive to any Tribal 

concerns that may arise.

Historic Preservation Fund

In 1977 the Historic Preservation Fund (54 U.S.C. §§ 303101-303103) was established to 

assist State and Tribal Historic Preservation Officers in their efforts to protect and preserve historic 

properties as set forth in the requirements of the National Historic Preservation Act. The Historic 

Preservation Fund is authorized at $150 million per year and is fully funded from OCS oil and gas 

revenues payable to the United States under Section 9 of the OCSLA (43 U.S.C. § 1338). However, 

these funds are available for expenditure only when appropriated by Congress, which has never fully 

appropriated the available funds. Since its inception, approximately $3.3 billion of the Historic 

Preservation Fund remains unappropriated (National Conference of State Historic Preservation 

Officers, 2015).

The Historic Preservation Fund’s monies may be used directly by State Historic Preservation 

Officers/Tribal Historic Preservation Officers or passed on as subgrants and contracts to public and 

private agencies, nonprofit organizations, educational institutions, and individuals. Eligible 
Consultation and Coordination 5-7 

preservation projects include historic properties’ survey and inventory, National Register of Historic 

Places’ nominations, preservation education, architectural planning, historic structure reports, 

community preservation planning, and brick and mortar repairs to buildings (USDOI, NPS, 2014b). 

These historic preservation programs can further catalyze community and neighborhood 

revitalization, job creation, and economic development, primarily through heritage tourism and the 

rehabilitation of historic properties through the Historic Tax Credit, which is administered by State 

Historic Preservation Officers. Since the Historic Preservation Fund was implemented in 1977, the 

Historic Tax Credit program nationwide has rehabilitated nearly 39,000 buildings, created 2.4 million 

jobs, created 140,000 low- and moderate-income housing units, and leveraged $109 billion in 

non-Federal investment (National Conference of State Historic Preservation Officers, 2014; USDOI, 

NPS, 2014b). In FY 2015, Congress allocated a total of $56.41 million from the Historic 

Preservation Fund, of which $46.925 million was awarded to State Historic Preservation Officers and 

$8.985 million was awarded to Tribal Historical Preservation Officers. An additional $500,000 was 

awarded for projects that will increase diversity in the National Register of Historic Places and the 

National Historic Landmarks Programs (National Conference of State Historic Preservation Officers, 

2015).

5.5 GOVERNMENT-TO-GOVERNMENT TRIBAL CONSULTATION

In accordance with Executive Order 13175, “Consultation and Coordination with Indian Tribal 

Governments,” Federal agencies are required to establish regular and meaningful consultation and 

collaboration with Tribal officials in the development of Federal policies that have Tribal implications 

to strengthen the United States’ government-to-government relationships with Indian Tribes, and to 

reduce the imposition of unfunded mandates upon Indian Tribes. On March 4, 2015, BOEM sent a 

formal letter to federally recognized Indian Tribes notifying them of the development of the 2017-

2022 Outer Continental Shelf Oil and Gas Leasing: Draft Proposed Program and the Gulf of Mexico 

OCS Proposed Geological and Geophysical Activities: Western, Central, and Eastern Planning 

Areas—Final Programmatic Environmental Impact Statement. That letter was addressed to each of 

the Gulf Coast State-affiliated Indian Tribes, including the Alabama-Coushatta Tribe of Texas, 

Caddo Nation of Oklahoma, Chitimacha Tribe of Louisiana, Choctaw Nation of Oklahoma, Coushatta 

Tribe of Louisiana, Jena Band of Choctaw Indians, Miccosukee Tribe of Indians of Florida, 

Mississippi Band of Choctaw Indians, Poarch Band of Creek Indians, Seminole Tribe of Florida, 

Seminole Nation of Oklahoma, and Tunica-Biloxi Indian Tribe of Louisiana. The letter was intended 

to be the first step of a long-term and broad consultation effort between BOEM and the Gulf-area 

Tribes, inclusive of all BOEM activities that may occur under the Draft Proposed Program, as well as 

ongoing activities. On May 19, 2016, another formal letter was sent announcing and soliciting 

consultation on the release of the 2017-2022 Proposed Program, Draft Five-Year Program EIS, and 

Draft 2017-2022 GOM Multisale EIS. That letter was sent to each of the above-listed Tribes, as well 

as to the Muscogee (Creek) Nation. As of this writing, no formal responses have been received in 

response to either the March 2015 or May 2016 letters; however, informal discussions with 

designated Tribal representatives are ongoing to determine if any of the individual Tribes desire 

continued consultations on these issues.
5-8 Gulf of Mexico Multisale EIS

The Poarch Band of Creek Indians has indicated that they do not have any specific concerns 

with BOEM’s activities on the OCS, but they would like to continue to receive notifications on 

BOEM’s activities (McCullers, official communication, 2015). Additionally, the Jena Band of 

Choctaw has indicated a general concern over adverse effects to documented or undocumented 

prehistoric and historic sites in the CPA and requests to be notified should such effects occur, as 

well as to continue being notified on BOEM’s activities (Shively, official communication, 2015a).

BOEM has also analyzed environmental justice issues for minority and low-income 

populations, which is broadly applicable to federally recognized Indian Tribes. Further information 

on that analysis can be found in Chapter 4.14.3.3. 

5.6 NATIONAL ENVIRONMENTAL POLICY ACT

5.6.1 Development of the Proposed Actions 

This Multisale EIS addresses 10 proposed regionwide Federal OCS oil and gas lease sales, 

as tentatively scheduled in the Proposed Final Program. BOEM conducted early coordination with 

appropriate Federal and State agencies and other concerned parties to discuss and coordinate the 

prelease process for the proposed lease sales and this Multisale EIS. Key agencies and 

organizations included FWS, NOAA, NOAA’s National Marine Fisheries Service, National Park 

Service, U.S. Coast Guard, U.S. Department of Defense, USEPA, State governors’ offices, federally

recognized Indian Tribes, industry, and nongovernmental organizations. The timeline for 

coordination with these agencies and concerned parties throughout the development of this

Multisale EIS is illustrated in Figure 5-1. 

Figure 5-1. Timeline for the Development of the Multisale EIS.

5.6.1.1 Notice of Intent to Prepare an EIS and Call for Information

On April 29, 2015, the Notice of Intent to Prepare an EIS (NOI) for the proposed regionwide 

lease sales was published in the Federal Register (2015h). Additional public notices, including 

individual consultation invitations to federally recognized Indian Tribes, were distributed via the U.S. 

Postal Service, local newspapers, and the Internet. A 30-day comment period was provided; it 

closed on June 1, 2015. Federal, State, and local governments, federally recognized Indian Tribes, 

nongovernmental organizations, other interested parties, and the public at large were invited to send 

written comments on the scope of the Multisale EIS to the Gulf of Mexico OCS Region. BOEM 
Consultation and Coordination 5-9 

received 10 comment letters in response to the NOI. These comments are summarized below in 

Chapter 5.6.2.2. 

Pursuant to the Outer Continental Shelf Lands Act of 1953, as amended (OCSLA), BOEM 

published a Call for Information (Call) to request and gather information to determine the Area 

Identification (Area ID) for each proposed lease sale. The Call was published in the Federal 

Register (2015a) on September 4, 2015. The Call invited potential bidders to nominate areas of 

interest within the program area(s) included in the 2017-2022 Draft Proposed Program. The Call 

was also an opportunity for the public to provide information on environmental, socioeconomic, and 

other considerations relevant to determining the Area ID.

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

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

summarized below in Chapter 5.6.1.2. 

5.6.1.2 Summary of Comments Received in Response to the Call for Information

In response to the Call, BOEM received one letter from the Louisiana Department of Natural 

Resources.

Louisiana Department of Natural Resources, Office of Coastal Management (letter dated 

September 29, 2015)

• The Louisiana Office of Coastal Management requests that BOEM consider 

secondary and cumulative impacts of OCS lease sales on coastal environments.

• BOEM should identify, quantify, and mitigate (e.g., compensatory mitigation) 

secondary and cumulative harm that occurs to Louisiana’s coastal wetlands. 

• BOEM should implement plans for validating predictions of social and 

environmental effects on coastal resources.

• Offshore exploration and development of hydrocarbon resources has been and 

continues to be of significant value to Louisiana and coastal communities.

5.6.1.3 Area ID Memorandum

Using information provided in response to the Call and from scoping comments, BOEM then 

developed an Area ID recommendation memorandum. The Area ID is an administrative prelease 

step that describes the geographical area for environmental analysis and consideration for leasing. 

All of this information is being used to develop the proposed action and a reasonable range of 

alternatives for this Multisale EIS.

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

proposed lease sales. The Area ID memo recommended keeping the entire regionwide area of the 
5-10 Gulf of Mexico Multisale EIS

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

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

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

5.6.2 Development of the Draft Multisale EIS

5.6.2.1 Scoping

Scoping for the Draft Multisale EIS was conducted in accordance with CEQ regulations for 

implementing NEPA. Internal scoping provides BOEM an opportunity to update the BOEM Gulf of 

Mexico OCS Region’s environmental and socioeconomic information base. The internal scoping 

process for the Draft Multisale EIS yielded the following:

• effort to make the document more reader-friendly by reducing the amount of text, 

optimizing the layout, and increasing the us e of graphics;

• a workshop was held for all subject-matter experts to reevaluate their resources 

and conclusions from prior lease sale EISs; 

• several resources have been reorganized or renamed to increase document 

readability and reduce redundancies: 

− Coastal Habitats (Estuarine Systems [Wetlands and Seagrasses/Submerged 

Vegetation] and Coastal Barrier Beaches and Associated Dunes);

− Deepwater Benthic Communities (Chemosynthetic Communities and

Deepwater Coral Communities);

− Nonchemosynthetic Communities has been renamed to Deepwater Coral

Communities;

− Sargassum Communities was renamed Sargassum and Associated 

Communities; 

− Live Bottom Habitats (Topographic Features and Pinnacles and Low-Relief

Features);

− Invertebrate Resources were added to the resource description for Fishes 

(i.e., Fishes and Invertebrate Resources);

− Coastal and Marine Birds was renamed to Birds;

− Protected Species (Marine Mammals, Sea Turtles, Beach Mice, Protected 

Birds, and Protected Corals);

− Commercial Fisheries will be re-focused on industry trends as the biological 

aspects are being addressed in the Fishes and Invertebrate Resources 

chapter; and

− Social Factors (Demographics and Environmental Justice);
Consultation and Coordination 5-11

• after careful consideration, the diamondback terrapin was eliminated from further 

analysis as a species of special concern as they are neither listed as endangered 

nor threatened by FWS nor are they likely to be impacted by a proposed action. 

Any potential impacts to diamondback terrapins would likely be as a result of 

their habitat location and, therefore, they are generally considered as part of the 

wetlands community. BOEM reserves the right to add them at a future date as 

designations and overall environmental indicators may change following 

consultations with, and concerns of, FWS; but at present, their inclusion is not 

warranted since the potential for impacts are speculative at best; and

• several white papers, which are incorporated by reference, were created and 

publicly released to reduce the amount of technical information contained in an

EIS, such as the catastrophic spill event analysis, the description of essential fish 

habitats, and the OCS regulatory framework.

Public scoping provides those with an interest in the OCS Program an opportunity to provide 

comments on the proposed actions. Public scoping meetings were held in Texas, Louisiana, 

Mississippi, Alabama, and Florida on the following dates and at the times and locations indicated 

below:

Tuesday, April 12, 2015

1:00 p.m. CDT

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

1201 Elmwood Park Boulevard

New Orleans, Louisiana 70123

2 registered attendees

0 speakers

0 verbal comments received

0 written comments received

Thursday, April 14, 2015

1:00 p.m. CDT

Hilton Garden Inn Houston/Bush 

Intercontinental Airport

15400 John F. Kennedy Boulevard

Houston, Texas 77032

1 registered attendee

0 speakers

0 verbal comments received

0 written comments received

Tuesday May 19, 2015

6:00 p.m. CDT

Hilton Garden Inn Panama City

1101 US Highway 231

Panama City, Florida 32405

2 registered attendees

0 speakers

0 verbal comments received

0 written comments received

Wednesday May 20, 2015

3:00 p.m. CDT

Hilton Garden Inn Mobile West

828 West I-65 Service Road South

Mobile, Alabama 36609

1 registered attendee

0 speakers

0 verbal comments received

0 written comments received
5-12 Gulf of Mexico Multisale EIS

Thursday May 21, 2015

3:00 p.m. CDT

Courtyard by Marriott

Gulfport Beachfront MS Hotel

1600 East Beach Boulevard

Gulfport, Mississippi 39501

1 registered attendee

0 speakers

0 verbal comments received

0 written comments received

5.6.2.2 Summary of Scoping Comments

In addition to accepting oral and written comments at each public meeting, BOEM accepted 

written comments by mail, email, and through the regulations.gov web portal 

(http://www.regulations.gov). BOEM received a total of 10 comments: 5 were mailed formal letters; 

3 were emails; and 2 were received through the regulations.gov web portal. Comments came from 

Federal and State agencies, interest groups, industry, and the general public on the scope of the this

Multisale EIS, significant issues that should be addressed, alternatives that should be considered, 

and mitigating measures. Each comment was read and categorized according to its source and the 

nature of the information included. All scoping comments received that were relevant for a lease 

sale NEPA document were considered in the preparation of the Draft Multisale EIS. The scope and 

content of this Multisale EIS was formulated to ensure that the relevant issues and concerns 

expressed by stakeholders during the scoping process were fully addressed. Summaries of 

comments received follow.

United States Environmental Protection Agency, Regions 4 and 6 (letter dated September 8, 

2015)

• The USEPA formally requested Cooperating Agency status for this Multisale EIS. 

As a cooperating agency, the USEPA will

− provide expertise on NEPA compliance and other applicable subject matters;

− provide timely technical reviews and comments on preliminary documents, 

reports, analyses, and sections of the Draft and Final Multisale EISs; 

− participate in meetings as resources allow;

− provide available information during preparation of the Draft and Final 

Multisale EISs in areas in which the USEPA has expertise; and

− review and comment on the Draft and Final Multisale EISs pursuant to 

USEPA regulatory responsibilities under Section 309 of the Clean Air Act.
Consultation and Coordination 5-13

Louisiana Department of Natural Resources, Office of Coastal Management (letter dated 

May 22, 2015)

• The Louisiana Office of Coastal Management requests that BOEM revisit the 

predictions of social and environmental effects on coastal resources made for 

earlier lease sales and compare them to existing environmental conditions.

• The State of Louisiana expressed that indirect and cumulative impacts to 

Louisiana’s coastal resources are not adequately addressed in previous EISs.

• The State of Louisiana is also concerned that Louisiana’s coastal wetlands are 

disproportionately bearing the impacts from OCS oil- and gas-related activities 

and requests compensatory mitigation. 

• Louisiana supports the expansion of exploration and development of Gulf of 

Mexico energy resources.

Louisiana Department of Culture, Recreation, and Tourism; State Historic Preservation Office 

(letter dated May 12, 2015)

• The Louisiana State Historic Preservation Office determined that the proposed 

actions will have no adverse effect on historic properties.

Florida Department of State, Division of Historical Resources (letter dated April 15, 2015 and 

email dated May 12, 2015)

• The State of Florida determined that BOEM’s proposed 2017-2022 GOM lease 

sales will have no effect on historic properties but requested to be notified if any 

cultural resources are identified (April 15, 2015).

• Florida clarified that they are primarily interested in resources that are identified 

off Florida that cannot be avoided (May 12, 2015). 

Alabama Historical Commission (letter dated April 30, 2015)

• The State of Alabama agreed that the proposed phased approach to meeting 

Section 106 requirements is reasonable and appropriate for the proposed 

actions. 

Conoco Philips (email dated April 28, 2015)

• Conoco Philips recommends that this Multisale EIS address the effects of the 

GOM lease sales using alternatives that are formulated to mitigate known risks or 

adverse impacts.

• BOEM must try to reach an appropriate balance of all oil and gas exploration and 

production, environmental protection, and potential impacts to coastal zone 

factors when implementing the Five-Year Program.
5-14 Gulf of Mexico Multisale EIS

• BOEM should apply its best available scientific analysis to operating scenarios 

that accurately reflects actual OCS oil- and gas-related activities that occur on a 

day-to-day basis.

• Conoco Philips opposes the use of mitigations based on the use of dated 

technologies for new studies or the reapplication of findings from previous 

studies that used out-of-date technology, as well as the use of studies outside 

normal parameters of oil and gas development.

The American Petroleum Institute (email dated May 29, 2015)

• The American Petroleum Institute recommends that the Multisale EIS be 

designed specifically with the idea that it will be used as a reference for future 

NEPA analysis.

• BOEM should consider the extensive safety improvements implemented by 

industry and new requirements imposed on offshore operations since the 

Deepwater Horizon explosion, oil spill, and response, particularly the formation of 

many well containment companies and their ability to assist in any potential 

future incidents.

Save the Manatee Club (regulations.gov submission dated May 29, 2015)

• The Save the Manatee Club requests NEPA analysis of the EPA in a separate 

process.

• The Multisale EIS analysis should assess the impacts from all aspects of 

offshore oil and gas development and the cultural value of resources, and it 

should differentiate the risks of deepwater drilling from those of less 

technologically difficult operations.

• BOEM should analyze an alternative that includes a buffer around the portions of 

the EPA that are under Congressional Moratorium.

Center for Biological Diversity (regulations.gov submission dated May 29, 2015)

• The Center for Biological Diversity asked BOEM to delay leasing until after the 

effects of the Deepwater Horizon explosion, oil spill, and response are known 

and the ecosystem has recovered.

• The Multisale EIS should consider the direct, indirect, and cumulative impacts of 

oil spills, including catastrophic spills, and consider the science that has been 

released since the Deepwater Horizon explosion, oil spill, and response.

• BOEM must also analyze the direct, indirect, and cumulative effects of oil and 

gas activities, particularly air, water, noise, and light pollution, and increased 

vessel traffic in relation to sensitive biological resources.
Consultation and Coordination 5-15

• The Center for Biological Diversity requested that BOEM consider the impacts of 

offshore fracking and a reasonable range of alternatives.

Jean Public (email dated April 29, 2015)

• Jean Public opposes the proposed actions due to the lack of safety changes 

since the Deepwater Horizon explosion, oil spill, and response.

5.6.2.3 Additional Public Input Opportunities

Although scoping is a formal, defined process initiated by the publication of the NOI and Call 

with an identified closing date, public input and other coordination meetings continue to proceed 

throughout this NEPA process. Public input and coordination opportunities were also available 

during BOEM’s requests for information, comments, input, and review of its other NEPA documents, 

including the following:

• Request for Information on the 2017-2022 Outer Continental Shelf Oil and Gas 

Leasing: Draft Proposed Program; 

• Notice of Availability for the 2017-2022 Outer Continental Shelf Oil and Gas 

Leasing: Draft Proposed Program; and

• Scoping for the 2017-2022 Five-Year Program EIS.

Comments from these additional public input opportunities are incorporated, where relevant,

in the Multisale EIS through the tiering process. One comment from the NPS was identified by 

BOEM’s 2017-2022 Five-Year Program EIS project team as more relevant to a regional NEPA

review. Therefore, it was considered during the preparation of this Multisale EIS. The NPS 

comment requested an exclusion zone south and within 15 mi (24 km) of the Mississippi portion of 

the Gulf Islands National Seashore.

5.6.2.4 Cooperating Agencies

According to Part 516 of the DOI Departmental Manual, BOEM must invite eligible 

government entities to participate as cooperating agencies when developing an EIS in accordance 

with the requirements of NEPA and CEQ regulations. BOEM must also consider any requests by 

eligible government entities to participate as a cooperating agency with respect to a particular EIS, 

and must either accept or deny such requests.

The NOI, which was published on April 29, 2015, included an invitation to other Federal 

agencies and State, Tribal, and local governments to consider becoming cooperating agencies in the 

preparation of this Multisale EIS. In a letter dated September 8, 2015, USEPA Regions 4 and 6 

requested cooperating agency status for this Multisale EIS. On December 16, 2015, a 

Memorandum of Agreement between BOEM and USEPA Regions 4 and 6 was initiated, which 

defines the roles and responsibilities for each agency (Appendix C). 
5-16 Gulf of Mexico Multisale EIS

5.6.2.5 Distribution of the Draft Multisale EIS for Review and Comment

BOEM sent copies of the Draft Multisale EIS to the government, public, and private agencies 

and groups listed below. Local libraries along the Gulf Coast were provided copies of this document; 

a list of these libraries is available on BOEM’s website at http://www.boem.gov/nepaprocess/. 

Federal Agencies

Congress

Congressional Budget Office

House Resources Subcommittee on 

Energy and Mineral Resources

Senate Committee on Energy and Natural 

Resources

Department of Commerce

National Oceanic and Atmospheric 

Administration

National Marine Fisheries Service

Department of Defense

Department of the Air Force

Department of the Army

Corps of Engineers

Department of the Navy

Naval Mine and Anti-Submarine 

Warfare Command

Department of Energy

Strategic Petroleum Reserve PMD

Department of Homeland Security

U.S. Coast Guard

Department of State

Bureau of Oceans and International 

Environmental and Scientific Affairs

Department of the Interior

Bureau of Ocean Energy Management

Bureau of Safety and Environmental 

Enforcement

Fish and Wildlife Service

Geological Survey

National Park Service

Office of Environmental Policy and 

Compliance

Office of the Solicitor

Department of Transportation

Pipeline and Hazardous Materials Safety 

Administration

Office of Pipeline Safety

Environmental Protection Agency

Region 4

Region 6

Marine Mammal Commission

State and Local Agencies

Alabama

Governor’s Office

Alabama Highway Department

Alabama Historical Commission and State

Historic Preservation Officer

Alabama Public Library Service

Alabama Public Service Commission

City of Mobile

City of Montgomery

Department of Conservation and Natural 

Resources

Department of Environmental 

Management

Geological Survey of Alabama

South Alabama Regional Planning 

Commission

State Legislature Natural Resources 

Committee

Town of Dauphin Island

Florida

Governor’s Office

Bay County

Citrus County

City of Destin

City of Fort Walton Beach

City of Gulf Breeze

City of Panama City

City of Pensacola

Department of Agriculture and Consumer 

Services

Department of Environmental Protection

Department of State Archives, History and 

Records Management

Escambia County

Florida Emergency Response 

Commission

Florida Fish and Wildlife Conservation 

Commission

Franklin County

Gulf County

Hernando County

Hillsborough City-County Planning 

Commission
Consultation and Coordination 5-17

Lee County

Monroe County

North Central Florida Regional Planning 

Council

Okaloosa County

Pasco County

Santa Rosa County

Sarasota County

Southwest Florida Regional Planning 

Council

State Legislature Agriculture and Natural 

Resources Committee

Tampa Bay Regional Planning Council

Walton County

West Florida Regional Planning Council

Withlacoochee Regional Planning Council

Louisiana

Governor’s Office

Calcasieu Parish

Cameron Parish

City of Grand Isle

City of Lake Charles

City of Morgan City

City of New Orleans

Department of Culture, Recreation, and 

Tourism

Department of Economic Development

Department of Environmental Quality

Department of Natural Resources

Department of Transportation and 

Development

Department of Wildlife and Fisheries

Houma-Terrebonne Chamber of 

Commerce

Jefferson Parish Director

Jefferson Parish President

Lafourche Parish Coastal Zone 

Management

Lafourche Parish Water District #1

Louisiana Geological Survey

South Lafourche Levee District

St. Bernard Planning Commission

State House of Representatives, Natural 

Resources Committee

State Legislature, Natural Resources 

Committee

State of Louisiana Library

Terrebonne Parish

Mississippi

Governor’s Office

City of Bay St. Louis

City of Gulfport

City of Pascagoula

Department of Archives and History

Department of Environmental Quality

Department of Marine Resources

Department of Wildlife, Fisheries, and 

Parks

Jackson-George Regional Library System

Mississippi Development Authority

State Legislature Oil, Gas, and Other 

Minerals Committee

Texas

Governor’s Office

Aransas Pass Public Library

Attorney General of Texas

Chambers County Library System

City of Lake Jackson

General Land Office

Southeast Texas Regional Planning 

Commission

State Legislature Natural Resources 

Committee

State Senate Natural Resources 

Committee

Texas Historical Commission

Texas Legislation Council

Texas Parks and Wildlife Department

Texas Sea Grant

Texas State Library and Archives

Texas Water Development Board

Federally Recognized Indian Tribes

Alabama-Coushatta Tribe of Texas

Caddo Nation of Oklahoma

Chitimacha Tribe of Louisiana

Choctaw Nation of Oklahoma

Coushatta Tribe of Louisiana

Jena Band of Choctaw Indians

Miccosukee Tribe of Indians of Florida

Mississippi Band of Choctaw Indians

Poarch Band of Creek Indians

Seminole Tribe of Florida

Seminole Nation of Oklahoma

Tunica-Biloxi Indian Tribe of Louisiana

Industry

Adams and Reese, LLP

Alabama Petroleum Council
5-18 Gulf of Mexico Multisale EIS

American Petroleum Institute

Applied Technology Research Corporation

Area Energy LLC

Associated Gas Distributors of Florida 

Baker Atlas

Baker Energy

Bepco, Inc.

C.H. Fenstermaker & Associates, Inc.

Century Exploration N.O., Inc.

Chet Morrison Contractors

Chevron U.S.A. Inc.

C-K Associates, LLC

Coastal Conservation Association

Coastal Environments, Inc.

Columbia Gulf Transmission

Continental Shelf Associates, Inc.

De Leon & Associates

Ecological Associates, Inc.

Ecology and Environment

Ecosystem Management, Inc.

Energy Partners, Ltd.

EOG Resources, Inc.

Exxon Mobil Production Company

Florida Natural Gas Association

Florida Petroleum Council

Florida Power and Light

Florida Propane Gas Association

Freeport-McMoRan, Inc.

General Insulation, Inc.

Global Industries, Ltd.

Gulf of Mexico Newsletter

Halliburton Corporation

Han & Associates, Inc.

Horizon Marine, Inc.

Industrial Vehicles International, Inc.

J. Connor Consultants

John Chance Land Surveys, Inc.

L&M Botruc Rental, Inc.

Lampl Herbert Consultants

Larose Intercoastal Lands, Inc.

Linder Oil Company

Louisiana Oil and Gas Association

Magnum Steel Services Corp.

Marine Safety Office

Mid-Continent Oil and Gas Association

Nature’s Way Marine, LLC

Newfield Exploration Company

Offshore Process Services, Inc.

Oil and Gas Property Management, Inc.

Phoenix International Holdings, Inc.

Project Consulting Services

R.B. Falcon Drilling

Raintree Resources, Inc.

Science Applications International 

Corporation

Seneca Resources Corporation

SEOT, Inc.

Shell Exploration & Production Company

Shell Offshore, Inc.

Stone Energy Corporation

Strategic Management Services-USA

T. Baker Smith, Inc.

Texas Geophysical Company, Inc.

The SJI, LLC

The Times-Picayune

The Washington Post

URS Corporation

W & T Offshore, Inc.

Waring & Associates

WEAR-TV

Special Interest Groups

1000 Friends of Florida

Alabama Oil & Gas Board

Alabama Nature Conservancy

Alabama Wildlife Federation

American Cetacean Society

Apalachee Regional Planning Council

Apalachicola Riverkeeper

Audubon Louisiana Nature Center

Audubon of Florida

Barataria-Terrebonne National Estuary 

Program

Bay County Chamber of Commerce

Bay Defense Alliance 

Capital Region Planning Commission

Center for Marine Conservation

Citizens Association of Bonita Beach

Clean Gulf Associates

Coalition to Restore Coastal Louisiana

Coastal Conservation Association

Concerned Shrimpers of America

Conservancy of Southwest Florida

Earthjustice

Florida Chamber of Commerce

Florida Natural Area Inventory

Florida Wildlife Federation 

Gulf and South Atlantic Fisheries

Foundation, Inc.

Gulf Coast Environmental Defense

Gulf Coast Fisherman’s Coalition

Gulf Restoration Network

Houma-Terrebonne Chamber of 

Commerce
Consultation and Coordination 5-19

LA 1 Coalition, Inc.

League of Women Voters of the 

Pensacola Bay Area

Louisiana Wildlife Federation

Manasota-88

Marine Mammal Commission

Mobile Bay National Estuary Program

Natural Resources Defense Council

Nature Conservancy

Offshore Operators Committee

Organized Fishermen of Florida

Panama City Beach Convention and 

Visitors Bureau

Pensacola Archaeological Society

Perdido Key Association

Perdido Key Chamber of Commerce

Perdido Watershed Alliance

Restore or Retreat

Roffers Ocean Fishing Forecast Service

Save the Manatee Club

Sierra Club

South Central Industrial Association

Surfrider Foundation

The Nature Conservancy

The Ocean Conservancy

Ports/Docks

Alabama

Alabama State Port Authority

Port of Mobile

Florida

Manatee County Port Authority

Panama City Port Authority

Port of Pensacola

Port St. Joe Port Authority

Tampa Port Authority

Louisiana

Abbeville Harbor and Terminal District

Grand Isle Port Commission

Greater Baton Rouge Port Commission

Greater Lafourche Port Commission

Lake Charles Harbor and Terminal District

Plaquemines Port, Harbor and Terminal 

District

Port of Baton Rouge

Port of Iberia District

Port of New Orleans

Twin Parish Port Commission

St. Bernard Port, Harbor and Terminal 

District

West Cameron Port Commission

Mississippi

Mississippi State Port Authority

Texas

Brownsville Navigation District—Port of 

Brownsville

Port Freeport

Port Mansfield/Willacy County Navigation 

District

Port of Beaumont

Port of Corpus Christi Authority

Port of Galveston

Port of Houston Authority

Port of Isabel—San Benito Navigation 

District

Port of Port Arthur Navigation District

Educational Institutions/Research 

Laboratories

Abilene Christian University

Dauphin Island Sea Laboratory

Florida A&M University

Florida Institute of Oceanography

Florida Institute of Technology

Florida Sea Grant College

Florida State University

Foley Elementary School

Gulf Coast Research Laboratory

Gulf Coast State College

Harbor Branch Oceanography

Louisiana Sea Grant College Program

Louisiana State University

Louisiana Tech University

Louisiana Universities Marine Consortium

Loyola University

McNeese State University

Mississippi State University

Mississippi-Alabama Sea Grant 

Consortium

Mote Marine Laboratory

Nicholls State University

Pensacola Junior College

Tulane University

University of Alabama

University of Florida

University of Louisiana at Lafayette

University of Miami
5-20 Gulf of Mexico Multisale EIS

University of Mississippi 

University of New Orleans

University of South Alabama

University of South Florida

University of Southern Mississippi

University of Texas at Arlington

University of Texas at Austin

University of Texas Law School

University of Texas Libraries

University of West Florida

5.6.3 Development of the Final Multisale EIS

5.6.3.1 Major Differences Between the Draft and Final Multisale EISs 

Several changes were made between the Draft and Final Multisale EISs. These changes 

were the result of new information becoming available, editorial suggestions, and comments 

received on the Draft Multisale EIS. Most notably, the air quality analysis in Chapter 4.1 has been 

updated with the recently available results of a modeling effort undertaken by BOEM. Chapter 5

has been reorganized to more clearly convey the consultations and coordination that took place 

during the preparation of this Multisale EIS. Comments on the Draft Multisale EIS were received via 

verbal, written, and electronic correspondence. As a result of these comments, changes have been 

made between the Draft and Final Multisale EISs. Where appropriate, the text in this Final Multisale 

EIS has been verified or expanded to provide clarification on specific issues, as well as to provide 

updated information. Some of the revisions made between the Draft and Final Multisale EISs 

changed the impact conclusion for the physical, environmental, and/or socioeconomic resources 

analyzed in this Multisale EIS, i.e., water quality (Chapter 4.2), coastal habitats (Chapter 4.3), 

marine mammals (Chapter 4.9.1), sea turtles (Chapter 4.9.2), and land use and coastal 

infrastructure (Chapter 4.14.1). For more information, refer to those respective chapters.

5.6.3.2 Public Meetings

In accordance with 30 CFR § 556.26, BOEM scheduled public meetings soliciting comments 

on the Draft Multisale EIS. The meetings were conducted to solicit information from interested 

parties in order to provide the Secretary of the Interior with information to help in the evaluation of 

the potential effects of the proposed lease sales. An announcement of the dates, times, and 

locations of the public meetings was included in the Notice of Availability of the Draft Multisale EIS. 

A copy of the public meetings’ notice was included with the Draft Multisale EIS that was mailed to 

the parties indicated above, was published in local newspapers, and was posted on BOEM’s website 

at http://www.boem.gov/nepaprocess/. 

Public meetings were held in Texas, Louisiana, Florida, Alabama, and Mississippi on the 

dates and at the times and locations indicated below:
Consultation and Coordination 5-21

Monday, May 9, 2016 Thursday, May 12, 2016

4:30 p.m. – 7:30 p.m. CDT 1:00 p.m. – 4:00 p.m. CDT

Holiday Inn Hotel and Suites Beaumont-Plaza Sheraton Metairie-New Orleans Hotel

3950 I-10 South at Walden Road 4 Galleria Boulevard

Beaumont, Texas 77705 Metairie, Louisiana 70001

12 registered attendees 19 registered attendees

3 speakers

1 written comment received

4 speakers

7 written comments received

Tuesday, May 17, 2016 Wednesday, May 18, 2016

4:30 p.m. – 7:30 p.m. CDT 4:30 p.m. – 7:30 p.m. CDT

Bay Point Golf Resort and Spa Renaissance Mobile Riverview Plaza Hotel

4114 Jan Cooley Drive 64 South Water Street

Panama City Beach, Florida 32408 Mobile, Alabama 36602

19 registered attendees 13 registered attendees

5 speakers 3 speakers

1 written comment received 1 written comment received

Thursday, May 19, 2016

4:30 p.m. – 7:30 p.m. CDT

Courtyard by Marriott, 

Gulfport Beachfront MS Hotel

1600 East Beach Boulevard

Gulfport, Mississippi 39501

21 registered attendees

8 speakers

3 written comments received

5.6.3.3 Comments Received on the Draft Multisale EIS and BOEM’s Responses

The Notice of Availability and the announcement of public meetings were published in the 

Federal Register on April 22, 2016; were posted on BOEM’s website; and were mailed to interested 

parties. The comment period ended on June 7, 2016. BOEM received over 250 distinct comments 

in response to the Draft Multisale EIS via letter, email, written and verbal comments at public 

meetings, and the regulations.gov website. BOEM also received 1,678 copies of a form letter, and a 

petition signed by 132,689 individuals requesting no new leases. All comments (i.e., letters, court 

reporter transcripts, emails, etc.) were analyzed to identify all substantive issues raised by the public. 

Each issue within an individual’s comment was assigned a unique identifier and then grouped into 

10 major categories. Within these 10 categories, responses are provided for each issue. When 

similar issues were raised by several commenters, a single response has been provided for multiple 

comments. The comments and responses are presented in a matrix in Appendix L and are 

organized by the following 10 topics:

Topic 1 – “NEPA Process and Public Involvement” contains those issues related to 

the process of preparing this Multisale EIS and the public’s engagement.
5-22 Gulf of Mexico Multisale EIS

Topic 2 – “NEPA Analysis” includes comments about how BOEM carried out its 

analysis under NEPA.

Topic 3 – “Alternatives” includes all of the comments related to the alternatives 

considered in the preparation of this Multisale EIS. A majority of these comments 

included a statement of the commenter’s preference for a particular alternative, with 

some including a reason why. A “Stated Preference” subtopic was included to group 

those comments.

Topic 4 – “Environmental Issues and Concerns” contains 16 subcategories that

include the following: 

• Climate Change

• Greenhouse Gases

• Well Stimulation

• Renewable Energy

• Alternative Use of the OCS

• Natural Stressors

• Air Quality

• Coastal Habitats

• Biologically Sensitive Areas

• Fish and Invertebrates

• Birds and Protected Birds

• Marine Mammals

• Sea Turtles

• Infrastructure

• Socioeconomics

• Environmental Justice

Topic 5 – “Cumulative Analysis” includes the comments BOEM received regarding 

the analysis of past, present, and reasonably foreseeable activities in this Multisale 

EIS.

Topic 6 – “Oil Spills” includes comments related to concerns over oil spills and their 

impact on the environment.

Topic 7 – “Mitigation” includes all of the comments that relate to how BOEM plans to 

minimize environmental impacts.
Consultation and Coordination 5-23

Topic 8 – “Regulations and Safety” includes comments on how BOEM and BSEE 

regulate offshore energy production and safety.

Topic 9 – “Statutory Compliance” includes all of the comments BOEM received about 

how it satisfied its statutory obligations under the OCSLA, NEPA, ESA, and several 

other acts.

Topic 10 – “Other” includes a wide range of comments that did not fall into one of the 

above categories (e.g., halting all future activities, questions about leasing 

procedures, and concern for industry practices).

CHAPTER 6 

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CHAPTER 7 

PREPARERS

Preparers 7-3

7 PREPARERS 

Gary D. Goeke, Chief, Environmental Assessment Section (retired)

Tershara Matthews, Unit 2 Supervisor, Environmental Protection Specialist

Helen Rucker, EIS Coordinator, Environmental Scientist

Ross Del Rio, EIS Co-Coordinator, Environmental Scientist

Mary Cody, Headquarters’ Coordinator, Environmental Protection Specialist

Bruce Baird, Biologist

Mark Belter, Marine Biologist

Idrissa Boube, Environmental Scientist

Darice K. Breeding, Environmental Protection Specialist (retired)

Brian Cameron, Senior Environmental Scientist

Alicia Caporaso, Marine Archaeologist

Sindey Chaky, Social Scientist

Nicole Charpentier, Protected Species Biologist

Leonard Coates, Supervisor, Mapping and Automation Section

Thierry DeCort, Chief, Geological and Geophysical Section

Chris DuFore, Oceanographer

Stephanie Gambino, Chief, Biological/Social Sciences Section

Donald (Tre) W. Glenn III, Protected Species Biologist

Stephen Gonzales, Geographer

Mike Gravois, Geographer

Jose Hernandez, Physical Scientist

Nikki Hughes, Protected Species Biologist

Jack Irion, Unit Supervisor, Marine Archaeologist

Mark Jensen, Economist

Douglas Jones, Senior Marine Archaeologist

Agatha-Marie Kaller, Unit Supervisor, Marine Biologist

Ariel Kay, Environmental Scientist

Pedro Levy, Geographer

Paula (Kaye) London, Protected Species Biologist

Christopher Lopinto, Data Quality Analyst

Charles (Jay) McCreery, Physical Scientist

Stacie Merritt, Physical Scientist

Margaret Metcalf, Chief, Physical/Chemical Sciences Section

Deborah Miller, Technical Editor

David Moran, Biologist

Mark Mueller, Marine Ecologist

Trevis Olivier, Environmental Scientist

Christopher Oos, Geographer

S. Erin O’Reilly, Physical Scientist

Catherine Rosa, Environmental Assessment Program Specialist

Shane Stradley, Geographer

Toby Wraye, Information Management Specialist

CHAPTER 8 

GLOSSARY

Glossary 8-3 

8 GLOSSARY

Acute—Sudden, short term, severe, critical, 

crucial, intense, but usually of short 

duration, as opposed to chronic. Effects 

associated with acute can vary depending 

on the context of its use (e.g., acute 

[short-term] exposure could be more or less 

problematic than chronic [long-term] 

exposure).

Anaerobic—Capable of growing in the absence 

of molecular oxygen.

Annular preventer—A component of the 

pressure control system in the BOP that

forms a seal in the annular space around 

any object in the wellbore or upon itself, 

enabling well control operations to 

commence.

Anthropogenic—Coming from human sources, 

relating to the effect of humankind on 

nature.

Antipatharian Transitional Zone—The area 

located between 50 and 90 m (164 and 

295 ft), where available light is reduced and 

there is a gradual ecosystem change from 

tropical shallow-water corals that are 

dependent on light to deeper water species, 

such as antipatharian black corals that are 

not.

API gravity—A standard adopted by the 

American Petroleum Institute for expressing 

the specific weight of oil.

Aromatic—Class of organic compounds 

containing benzene rings or benzenoid 

structures.

Attainment area—An area that is shown by 

monitored data or by air-quality modeling 

calculations to be in compliance with 

primary and secondary ambient air quality 

standards established by USEPA.

Barrel (bbl)—A volumetric unit used in the 

petroleum industry; equivalent to 42 U.S. 

gallons or 158.99 liters.

Benthic—On or in the bottom of the sea.

Biological Opinion—The FWS or NMFS 

evaluation of the impact of a proposed 

action on endangered and threatened 

species, in response to formal consultation 

under Section 7 of the Endangered Species 

Act.

Block—A geographical area portrayed on 

official BOEM protraction diagrams or 

leasing maps that contains approximately 

5,760 ac (2,331 ha; 9 mi2

).

Blowout—An uncontrolled flow of fluids below 

the mudline from appurtenances on a

wellhead or from a wellbore.

Blowout preventer (BOP)—One of several 

valves installed at the wellhead to prevent 

the escape of pressure either in the annular 

space between the casing and drill pipe or 

in open hole (i.e., hole with no drill pipe) 

during drilling completion operations. 

Blowout preventers on jackup or platform 

rigs are located at the water’s surface; on 

floating offshore rigs, BOPs are located on 

the seafloor.

Cetacean—Aquatic mammal of the order 

Cetacea, such as whales, dolphins, and 

porpoises.

Chemosynthetic—Organisms that obtain their 

energy from the oxidation of various 

inorganic compounds rather than from light 

(photosynthetic).

Coastal waters—Waters within the 

geographical areas defined by each State’s 

Coastal Zone Management Program.
8-4 Gulf of Mexico Multisale EIS

Coastal wetlands—forested and nonforested 

habitats, mangroves, and marsh islands 

exposed to tidal activity. These areas 

directly contribute to the high biological 

productivity of coastal waters by input of 

detritus and nutrients, by providing nursery 

and feeding areas for shellfish and finfish, 

and by serving as habitat for birds and other 

animals.

Coastal zone—The coastal waters (including 

the lands therein and thereunder) and the 

adjacent shorelands (including the waters 

therein and thereunder) strongly influenced 

by each other and in proximity to the 

shorelines of several coastal states; the 

zone includes islands, transitional and 

intertidal areas, salt marshes, wetlands, and 

beaches, and it extends seaward to the 

outer limit of the United States territorial 

sea. The zone extends inland from the 

shorelines only to the extent necessary to 

control shorelands, the uses of which have 

a direct and significant impact on the coastal 

waters. Excluded from the coastal zone are 

lands the use of which is by law subject to 

the discretion of or which is held in trust by 

the Federal Government, its officers, or 

agents (also refer to State coastal zone 

boundaries). 

Completion—Conversion of a development 

well or an exploration well into a production 

well.

Condensate—Liquid hydrocarbons produced 

with natural gas; they are separated from 

the gas by cooling and various other means. 

Condensates generally have an API gravity 

of 50°-120°.

Continental margin—The ocean floor that lies 

between the shoreline and the abyssal 

ocean floor, includes the continental shelf, 

continental slope, and continental rise.

Continental shelf—General term used by 

geologists to refer to the continental margin 

province that lies between the shoreline and 

the abrupt change in slope called the shelf 

edge, which generally occurs in the Gulf of 

Mexico at about the 200-m (656-ft) water 

depth. The continental shelf is 

characterized by a gentle slope (about 0.1°). 

This is different from the juridical term used 

in Article 76 of the United Nations 

Convention on the Law of the Sea Royalty 

Payment (refer to the definition of Outer 

Continental Shelf).

Continental slope—The continental margin 

province that lies between the continental 

shelf and continental rise, characterized by 

a steep slope (about 3°-6°).

Critical habitat—Specific areas essential to the 

conservation of a protected species and that 

may require special management 

considerations or protection.

Crude oil—Petroleum in its natural state as it 

emerges from a well or after it passes 

through a gas-oil separator, but before 

refining or distillation. An oily, flammable, 

bituminous liquid that is essentially a 

complex mixture of hydrocarbons of 

different types with small amounts of other 

substances.

Delineation well—A well that is drilled for the 

purpose of determining the size and/or 

volume of an oil or gas reservoir.

Demersal—Living at or near the bottom of the 

sea.

Development—Activities that take place 

following discovery of economically 

recoverable mineral resources, including 

geophysical surveying, drilling, platform 

construction, operation of onshore support 

facilities, and other activities that are for the 
Glossary 8-5 

purpose of ultimately producing the 

resources.

Development and Production Plan (DPP)—A 

document that must be prepared by the 

operator and submitted to BOEM for 

approval before any development and 

production activities are conducted on a 

lease or unit in any OCS area other than the 

western Gulf of Mexico.

Development Operations Coordination 

Document (DOCD)—A document that must 

be prepared by the operator and submitted 

to BOEM for approval before any 

development or production activities are 

conducted on a lease in the western Gulf of 

Mexico.

Development well—A well drilled to a known 

producing formation to extract oil or gas; a 

production well; distinguished from a wildcat 

or exploration well and from an offset well.

Direct employment—Consists of those 

workers involved in the primary industries of 

oil and gas exploration, development, and 

production operations (Standard Industrial 

Classification Code 13—Oil and Gas 

Extraction).

Discharge—Something that is emitted; flow 

rate of a fluid at a given instant expressed 

as volume per unit of time.

Dispersant—A suite of chemicals and solvents 

used to break up an oil slick into small 

droplets, which increases the surface area 

of the oil and hastens the processes of 

weathering and microbial degradation.

Dispersion—A suspension of finely divided 

particles in a medium.

Drilling mud—A mixture of clay, water or 

refined oil, and chemical additives pumped 

continuously downhole through the drill pipe 

and drill bit, and back up the annulus 

between the pipe and the walls of the 

borehole to a surface pit or tank. The mud 

lubricates and cools the drill bit, lubricates 

the drill pipe as it turns in the wellbore, 

carries rock cuttings to the surface, serves 

to keep the hole from crumbling or 

collapsing, and provides the weight or 

hydrostatic head to prevent extraneous

fluids from entering the well bore and to 

downhole pressures; also called drilling 

fluid.

Economically recoverable resources—An 

assessment of hydrocarbon potential that 

takes into account the physical and 

technological constraints on production and 

the influence of costs of exploration and 

development and market price on industry 

investment in OCS exploration and 

production.

Effluent—The liquid waste of sewage and 

industrial processing.

Effluent limitations—Any restriction 

established by a State or USEPA on 

quantities, rates, and concentrations of 

chemical, physical, biological, and other 

constituents discharged from point sources 

into U.S. waters, including schedules of 

compliance.

Epifaunal—Animals living on the surface of 

hard substrate.

Essential habitat—Specific areas crucial to the 

conservation of a species and that may 

necessitate special considerations.

Estuary—Coastal semienclosed body of water 

that has a free connection with the open sea 

and where freshwater meets and mixes with 

seawater.
8-6 Gulf of Mexico Multisale EIS

Eutrophication—Enrichment of nutrients in the 

water column by natural or artificial methods 

accompanied by an increase of respiration, 

which may create an oxygen deficiency.

Exclusive Economic Zone (EEZ)—The 

maritime region extending 200 nmi (230 mi; 

370 km) from the baseline of the territorial 

sea, in which the United States has 

exclusive rights and jurisdiction over living 

and nonliving natural resources.

Exploration Plan (EP)—A plan that must be 

prepared by the operator and submitted to 

BOEM for approval before any exploration 

or delineation drilling is conducted on a 

lease.

Exploration well—A well drilled in unproven or 

semi-proven territory to determining whether 

economic quantities of oil or natural gas 

deposit are present.

False crawls—Refers to when a female sea 

turtle crawls up on the beach to nest 

(perhaps) but does not and returns to the 

sea without laying eggs.

Field—An accumulation, pool, or group of pools 

of hydrocarbons in the subsurface. A 

hydrocarbon field consists of a reservoir in a 

shape that will trap hydrocarbons and that is 

covered by an impermeable, sealing rock.

Floating production, storage, and offloading 

(FPSO) system—A tank vessel used as a 

production and storage base; produced oil is 

stored in the hull and periodically offloaded 

to a shuttle tanker for transport to shore.

Gathering lines—A pipeline system used to 

bring oil or gas production from a number of 

separate wells or production facilities to a 

central trunk pipeline, storage facility, or 

processing terminal.

Geochemical—Of or relating to the science 

dealing with the chemical composition of 

and the actual or possible chemical changes 

in the crust of the earth.

Geophysical survey—A method of exploration 

in which geophysical properties and 

relationships are measured remotely by one 

or more geophysical methods.

Habitat—A specific type of environment that is 

occupied by an organism, a population, or a 

community.

Hermatypic coral—Reef-building corals that 

produce hard, calcium carbonate skeletons 

and that possess symbiotic, unicellular 

algae within their tissues.

Harassment—An intentional or negligent act or 

omission that creates the likelihood of injury 

to wildlife by annoying it to such an extent 

as to significantly disrupt normal behavior 

patterns that include, but are not limited to, 

feeding or sheltering.

Hermatypic—Corals in the order Scleractinia 

that build reefs by depositing hard

calcareous material for their skeletons,

forming the stony framework of the reef. 

Corals that do not contribute to coral reef

development are referred to as ahermatypic

(non-reef-building) species.

Hydrocarbons—Any of a large class of organic 

compounds containing primarily carbon and 

hydrogen. Hydrocarbon compounds are 

divided into two broad classes: aromatic 

and aliphatics. They occur primarily in 

petroleum, natural gas, coal, and bitumens.

Hypoxia—Depressed levels of dissolved 

oxygen in water, usually resulting in 

decreased metabolism.

Incidental take—Takings that result from, but 

are not the purpose of, carrying out an 
Glossary 8-7 

otherwise lawful activity (e.g., fishing) 

conducted by a Federal agency or applicant 

(refer to Taking).

Infrastructure—The facilities associated with 

oil and gas development, e.g., refineries, 

gas processing plants, etc.

Jack-up rig—A barge-like, floating platform with 

legs at each corner that can be lowered to 

the sea bottom to raise the platform above 

the water.

Kick—A deviation or imbalance, typically 

sudden or unexpected, between the 

downward pressure exerted by the drilling 

fluid and the upward pressure of in-situ

formation fluids or gases.

Landfall—The site where a marine pipeline 

comes to shore.

Lease—Authorization that is issued under 

Section 8 or maintained under Section 6 of 

the Outer Continental Shelf Lands Act and 

that authorizes exploration for, and 

development and production of, minerals.

Lease sale—The competitive auction of leases 

granting companies or individuals the right 

to explore for and develop certain minerals 

under specified conditions and periods of 

time.

Lease term—The initial period for oil and gas 

leases, usually a period of 5, 8, or 10 years 

depending on water depth or potentially 

adverse conditions.

Lessee—A party authorized by a lease, or an 

approved assignment thereof, to explore for 

and develop and produce the leased 

deposits in accordance with regulations at 

30 CFR part 250 and 30 CFR part 550. 

Littoral zone—Marine ecological realm that 

experiences the effects of tidal and 

longshore currents and breaking waves to a 

depth of 5-10 m (16-33 ft) below the low-tide 

level, depending on the intensity of storm 

waves.

Longshore sediment transport—The

cumulative movement of beach sediment 

along the shore (and nearshore) by waves

arriving at an angle to the coastline and by 

currents generated by such waves. 

Macondo—Prospect name given by BP to the 

Mississippi Canyon Block 252 exploration 

well that the Deepwater Horizon rig was 

drilling when a blowout occurred on April 20, 

2010.

Macondo spill—The name given to the oil spill 

that resulted from the explosion and sinking 

of the Deepwater Horizon rig from the 

period between April 24, 2010, when search 

and recovery vessels on site reported oil at 

the sea surface, and September 19, 2010,

when the uncontrolled flow from the 

Macondo well was capped. 

Marshes—Persistent, emergent, nonforested 

wetlands characterized by predominantly 

cordgrasses, rushes, and cattails.

Military warning area—An area established by 

the U.S. Department of Defense within 

which military activities take place.

Minerals—As used in this document, minerals 

include oil, gas, sulphur, and associated 

resources, and all other minerals authorized 

by an Act of Congress to be produced from 

public lands as defined in Section 103 of the 

Federal Land Policy and Management Act 

of 1976.

Naturally occurring radioactive materials 

(NORM)—naturally occurring material that 

emits low levels of radioactivity, originating 

from processes not associated with the 
8-8 Gulf of Mexico Multisale EIS

recovery of radioactive material. The 

radionuclides of concern in NORM are 

Radium-226, Radium-228, and other 

isotopes in the radioactive decay chains of 

uranium and thorium.

Nepheloid—A layer of water near the bottom 

that contains significant amounts of 

suspended sediment.

Nonattainment area—An area that is shown by 

monitoring data or by air-quality modeling 

calculations to exceed primary or secondary 

ambient air quality standards established by 

USEPA.

Nonhazardous oil-field wastes (NOW)—

Wastes generated by exploration, 

development, or production of crude oil or 

natural gas that are exempt from hazardous 

waste regulation under the Resource 

Conservation and Recovery Act (Regulatory 

Determination for Oil and Gas and 

Geothermal Exploration, Development and 

Production Wastes, dated June 29, 1988, 

53 FR 25446; July 6, 1988). These wastes 

may contain hazardous substances.

Oceanic zone—Offshore water >200 m (656 ft) 

deep. It is the region of open sea beyond 

the edge of the continental shelf and 

includes 65 percent of the ocean's

completely open water.

Offloading—Unloading liquid cargo, crude oil, 

or refined petroleum products.

Operational discharge—Any incidental 

pumping, pouring, emitting, emptying, or 

dumping of wastes generated during routine 

offshore drilling and production activities.

Operator—An individual, partnership, firm, or 

corporation having control or management 

of operations on a leased area or portion 

thereof. The operator may be a lessee, 

designated agent of the lessee, or holder of 

operating rights under an approved 

operating agreement.

Organic matter—Material derived from living 

plants or animals.

Outer Continental Shelf (OCS)—All 

submerged lands that comprise the 

continental margin adjacent to the United 

States and seaward of State offshore lands.

Passerines—Perching birds (members of the 

Order Passeriformes) and songbirds.

Potential Biological Removal (PBR)—Of or 

pertaining to the open sea; associated with 

open water beyond the direct influence of 

coastal systems.

Pelagic—Of or pertaining to the open sea; 

associated with open water beyond the 

direct influence of coastal systems.

Plankton—Passively floating or weakly motile 

aquatic plants (phytoplankton) and animals 

(zooplankton).

Platform—A steel or concrete structure from 

which offshore development wells are 

drilled.

Play—A prospective subsurface area for 

hydrocarbon accumulation that is 

characterized by a particular structural style 

or depositional relationship.

Primary production—Organic material 

produced by photosynthetic or 

chemosynthetic organisms.

Produced water—Total water discharged from 

the oil and gas extraction process; 

production water or production brine.

Production—Activities that take place after the 

successful completion of any means for the 

extraction of resources, including bringing 
Glossary 8-9 

the resource to the surface, transferring the 

produced resource to shore, monitoring 

operations, and drilling additional wells or 

workovers.

Province—A spatial entity with common 

geologic attributes. A province may include 

a single dominant structural element such 

as a basin or a fold belt, or a number of 

contiguous related elements.

Ram—The main component of a blowout 

preventer designed to shear casing and 

tools in a wellbore or to seal an empty 

wellbore. A blind shear ram accomplishes 

the former and a blind ram the latter.

Recoverable reserves—The portion of the 

identified hydrocarbon or mineral resource 

that can be economically extracted under 

current technological constraints.

Recoverable resource estimate—An 

assessment of hydrocarbon or mineral 

resources that takes into account the fact 

that physical and technological constraints 

dictate that only a portion of resources can 

be brought to the surface.

Recreational beaches—Frequently visited, 

sandy areas along the Gulf of Mexico 

shorefront that support multiple recreational 

activities at the land-water interface. 

Included are National Seashores, State 

Park and Recreational Areas, county and 

local parks, urban beachfronts, and private 

resorts.

Refining—Fractional distillation of petroleum, 

usually followed by other processing (e.g., 

cracking).

Relief—The difference in elevation between the 

high and low points of a surface.

Reserves—Proved oil or gas resources.

Rig—A structure used for drilling an oil or gas 

well.

Riser insertion tube tool—A “straw” and 

gasket assembly improvised during the 

Macondo spill response that was designed 

to siphon oil and gas from the broken riser 

of the Deepwater Horizon rig lying on the 

sea bottom (an early recovery strategy for 

the Macondo spill in May 2010). 

Royalty—A share of the minerals produced 

from a lease paid in either money or “inkind” to the landowner by the lessee.

Saltwater intrusion—Saltwater invading a 

body of freshwater.

Sciaenids—Fishes belonging to the croaker 

family (Sciaenidae).

Seagrass beds—More or less continuous mats 

of submerged, rooted, marine, flowering 

vascular plants occurring in shallow tropical 

and temperate waters. Seagrass beds 

provide habitat, including breeding and 

feeding grounds, for adults and/or juveniles 

of many of the economically important 

shellfish and finfish.

Sediment—Material that has been transported 

and deposited by water, wind, glacier, 

precipitation, or gravity; a mass of deposited 

material.

Seeps (hydrocarbon)—Gas or oil that reaches 

the surface along bedding planes, fractures, 

unconformities, or fault planes.

Sensitive area—An area containing species, 

populations, communities, or assemblages 

of living resources, that is susceptible to 

damage from normal OCS oil- and gasrelated activities. Damage includes 

interference with established ecological 

relationships.
8-10 Gulf of Mexico Multisale EIS

Shear ram—The component in a BOP that 

cuts, or shears, through the drill pipe and 

forms a seal against well pressure. Shear 

rams are used in floating offshore drilling 

operations to provide a quick method of 

moving the rig away from the hole when 

there is no time to trip the drill stem out of 

the hole.

Site fidelity or philopatry—The tendency to 

return to a previously occupied location.

Spill of National Significance—Designation by 

the USEPA Administrator under 40 CFR § 

300.323 for discharges occurring in the 

inland zone and the Commandant of the 

U.S. Coast Guard for discharges occurring 

in the coastal zone, authorizing the 

appointment of a National Incident 

Commander for spill-response activity.

State coastal zone boundary—The State 

coastal zone boundaries for each CZMAaffected State are defined at 

https://coast.noaa.gov/czm/media/StateCZB

oundaries.pdf. 

Structure—Any OCS facility that extends from 

the seafloor to above the waterline; in 

petroleum geology, any arrangement of 

rocks that may hold an accumulation of oil 

or gas.

Subarea—A discrete analysis area.

Subsea isolation device—An emergency 

disconnection and reconnection assembly 

for the riser at the seafloor. 

Supply vessel—A boat that ferries food, water, 

fuel, and drilling supplies and equipment to 

an offshore rig or platform and returns to 

land with refuse that cannot be disposed of 

at sea.

Taking—To harass, harm, pursue, hunt, shoot, 

wound, kill, trap, capture, or collect any 

endangered or threatened species, or to 

attempt to engage in any such conduct 

(including actions that induce stress, 

adversely impact critical habitat, or result in 

adverse secondary or cumulative impacts). 

Harassments are the most common form of 

taking associated with OCS Program 

activities.

Tension-leg platform (TLP)—A production 

structure that consists of a buoyant platform 

tethered to concrete pilings on the seafloor 

with flexible cable.

Tidal prism—The volume of water in an estuary 

or inlet between mean high tide and mean 

low tide, or the volume of water leaving an 

estuary at ebb tide.

Trunkline—A large-diameter pipeline receiving 

oil or gas from many smaller tributary 

gathering lines that serve a large area; 

common-carrier line; main line.

Turbidity—Reduced water clarity due to the 

presence of suspended matter.

Volatile organic compound (VOC)—Any 

organic compound that is emitted to the 

atmosphere as a vapor.

Water test areas—Areas within the eastern 

Gulf where U.S. Department of Defense 

research, development, and testing of 

military planes, ships, and weaponry take 

place.

Weathering (of oil)—The aging of oil due to its 

exposure to the atmosphere, causing 

marked alterations in its physical and 

chemical makeup.

The Department of the Interior Mission

The Department of the Interior protects and manages the Nation’s natural 

resources and cultural heritage; provides scientific and other information 

about those resources; and honors the Nation’s trust responsibilities or 

special commitments to American Indians, Alaska Natives, and affiliated 

island communities.

The Bureau of Ocean Energy Management Mission

The Bureau of Ocean Energy Management (BOEM) is responsible for 

managing development of U.S. Outer Continental Shelf energy and mineral 

resources in an environmentally and economically responsible way.