Final Ocean Discharge Criteria Evaluation 

of the 

Arctic NPDES General Permit for Oil and Gas Exploration

(Permit No.: AKG280000) 

January 24, 2006 

Finalized By: 

U.S. Environmental Protection Agency 

Region 10, Office of Water and Watersheds 

Seattle, WA 

Prepared By: 

Tetra Tech, Inc. 

6100 219th St. SW, Suite 550 

Mountlake Terrace, WA 98043 
[page left blank intentionally]
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TABLE OF CONTENTS 

Section Page

1.0 INTRODUCTION.................................................................................................... 1-1 

1.1 PURPOSE OF EVALUATION..................................................................... 1-1 

1.2 SCOPE OF EVALUATION.......................................................................... 1-2 

1.2.1 Beaufort Sea Area of Coverage ......................................................... 1-3 

1.2.2 Chukchi Sea Area of Coverage.......................................................... 1-5 

1.2.3 Hope Basin Area of Coverage ........................................................... 1-5 

1.2.4 Norton Sound Area of Coverage........................................................ 1-5 

1.2.5 Duration of Activity........................................................................... 1-6 

1.3 OVERVIEW OF REPORT............................................................................ 1-6 

2.0 COMPOSITION AND QUANTITIES OF MATERIALS DISCHARGED....... 2-1 

2.1 TYPES OF DISCHARGES FROM DRILLING ACTIVITIES.................... 2-1 

2.2 DRILLING FLUIDS AND CUTTINGS ....................................................... 2-1 

2.2.1 Number and Types of Exploratory Wells .......................................... 2-3 

2.2.2 Control of Discharge.......................................................................... 2-5 

2.2.3 Composition of Drilling Fluids.......................................................... 2-5 

2.2.4 Composition of Drilling Cuttings ...................................................... 2-8 

2.2.5 Quantity Discharged .......................................................................... 2-8 

2.2.6 Summary.......................................................................................... 2-10 

2.3 MISCELLANEOUS DISCHARGES .......................................................... 2-10 

2.3.1 Deck Drainage ................................................................................. 2-11 

2.3.2 Sanitary and Domestic Waste .......................................................... 2-12 

2.4 MINOR DISCHARGES .............................................................................. 2-14 

2.4.1 Blowout Preventer Fluid.................................................................. 2-14 

2.4.2 Desalination Unit ............................................................................. 2-14 

2.4.3 Fire Control System Test Water ...................................................... 2-15 

2.4.4 Non-Contact Cooling Water ............................................................ 2-15 

2.4.5 Ballast Water.................................................................................... 2-15 

2.4.6 Bilge Water ...................................................................................... 2-16 

2.4.7 Boiler Blowdown............................................................................. 2-16 

2.4.8 Test Fluids........................................................................................ 2-16 

2.4.9 Excess Cement Slurry...................................................................... 2-17 

2.4.10 Mud, Cuttings, Cement at Seafloor.................................................. 2-17 

3.0 TRANSPORT, PERSISTENCE, AND FATE OF MATERIALS 

DISCHARGED ........................................................................................................ 3-1 

3.1 PHYSICAL TRANSPORT PROCESSES..................................................... 3-1 

3.1.1 Climate and Meteorology .............................................................................. 3-2 

3.1.2 Oceanography ................................................................................................ 3-4 

3.1.3 Upper Plume Transport Processes ............................................................... 3-11 

3.1.4 Lower Plume Transport Processes............................................................... 3-13 
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TABLE OF CONTENTS (cont.) 

3.1.5 Seafloor Sedimentation................................................................................ 3-13 

3.1.6 Studies in Arctic Alaska............................................................................... 3-14 

3.1.7 Predictive Modeling of Drilling Mud Transport, Deposition, and Dilution 3-24 

3.2 CHEMICAL TRASNPORT PROCESSES ................................................. 3-31 

3.2.1 Inorganics..................................................................................................... 3-31 

3.2.2 Organics ....................................................................................................... 3-32 

3.3 BIOLOGICAL TRANSPORT PROCESSES.............................................. 3-33 

3.3.1 Bioaccumulation .......................................................................................... 3-34 

3.3.2 Biomagnification.......................................................................................... 3-39 

3.3.3 Ingestion and Excretion ............................................................................... 3-41 

3.3.4 Bioturbation ................................................................................................. 3-41 

4.0 BIOLOGICAL RESOURCES................................................................................ 4-1 

4.1 PLANKTON.................................................................................................. 4-3 

4.1.1 Phytoplankton ................................................................................................ 4-3 

4.1.2 Zooplankton ................................................................................................... 4-5 

4.1.3 Effects Analysis ............................................................................................. 4-6 

4.2 ATTACHED MACROALGAE AND MICROALGAE ............................... 4-6 

4.2.1 Macroalgae..................................................................................................... 4-6 

4.2.2 Microalgae ..................................................................................................... 4-8 

4.2.3 Effects Analysis ............................................................................................. 4-9 

4.3 BENTHIC INVERTEBRATES................................................................... 4-10 

4.3.1 Distribution and Abundance ........................................................................ 4-10 

4.3.2 Growth and Production................................................................................ 4-12 

4.3.3 Environmental Factors................................................................................. 4-12 

4.3.4 Critical Areas or Habitat .............................................................................. 4-13 

4.3.5 Effects Analysis ........................................................................................... 4-13 

4.4 FISHES ........................................................................................................ 4-15 

4.4.1 Distribution and Abundance ........................................................................ 4-15 

4.4.2 Growth and Production................................................................................ 4-17 

4.4.3 Environmental Factors................................................................................. 4-18 

4.4.4 Critical Areas or Habitats............................................................................. 4-19 

4.4.5 Effects Analysis ........................................................................................... 4-19 

4.5 MARINE MAMMALS................................................................................ 4-20 

4.5.1 Distribution and Abundance ........................................................................ 4-20 

4.5.2 Growth and Production................................................................................ 4-23 

4.5.3 Environmental Factors................................................................................. 4-24 

4.5.4 Critical Areas or Habitats............................................................................. 4-25 

4.5.5 Effects Analysis ........................................................................................... 4-26 

4.6 COASTAL AND MARINE BIRDS............................................................ 4-26 

4.6.1 Distribution and Abundance ........................................................................ 4-27 

4.6.2 Growth and Production................................................................................ 4-28 

4.6.3 Environmental Factors................................................................................. 4-29 
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TABLE OF CONTENTS (cont.) 

4.6.4 Critical Areas or Habitats............................................................................. 4-30 

4.6.5 Effects Analysis ........................................................................................... 4-32 

4.7 THREATENED AND ENDANGERED SPECIES..................................... 4-32 

4.7.1 Short-tailed Albatross .................................................................................. 4-33 

4.7.2 Spectacled Eider........................................................................................... 4-34 

4.7.3 Steller’s Eider............................................................................................... 4-36 

4.7.4 Blue Whale................................................................................................... 4-39 

4.7.5 Bowhead Whale........................................................................................... 4-40 

4.7.6 Fin Whale..................................................................................................... 4-42 

4.7.7 Humpback Whale......................................................................................... 4-44 

4.7.8 North Pacific Right Whale........................................................................... 4-46 

4.7.9 Sperm Whale................................................................................................ 4-48 

4.7.10 Steller Sea Lion............................................................................................ 4-50 

4.7.11 Uncertainty Evaluation ................................................................................ 4-51 

4.7.12 Issues of Take .............................................................................................. 4-56 

4.8 ESSENTIAL FISH HABITAT.................................................................... 4-57 

4.8.1 Red King Crab ............................................................................................. 4-57 

4.8.2 Blue King Crab ............................................................................................ 4-58 

4.8.3 Snow Crab.................................................................................................... 4-58 

4.8.4 Yellow Fin Sole ........................................................................................... 4-59 

4.8.5 Sculpins........................................................................................................ 4-60 

4.8.6 Pacific Salmon ............................................................................................. 4-60 

4.8.7 Effects Analysis ........................................................................................... 4-66 

4.9 CUMULATIVE EFFECTS ANALYSIS..................................................... 4-67 

4.10 CONSERVATION MEASURES ................................................................ 4-68 

4.10.1 Area Restrictions.......................................................................................... 4-68 

4.10.2 Seasonal Restrictions ................................................................................... 4-68 

4.10.3 Environmental Monitoring Requirements ................................................... 4-69 

4.10.4 Limitation on Number of Wells Drilled....................................................... 4-69 

4.10.5 Restrictions on Discharges of Mineral Oil Pills .......................................... 4-69 

4.10.6 Toxicity Testing Requirements.................................................................... 4-69 

4.10.7 Quality Assurance Plan................................................................................ 4-69 

4.10.8 Best Management Practices Plan................................................................. 4-70 

4.10.9 Drilling Fluid Plan ....................................................................................... 4-70 

5.0 HUMAN HEALTH.................................................................................................. 5-1 

5.1 DIRECT EXPOSURE ................................................................................... 5-1 

5.2 CONSUMPTION OF EXPOSED AQUATIC SPECIES.............................. 5-1 

5.2.1 Subsistence Consumption .............................................................................. 5-1 

5.2.2 Effects Analysis ............................................................................................. 5-4 

6.0 TRIBAL RESOURCES........................................................................................... 6-1 
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TABLE OF CONTENTS (cont.) 

7.0 RECREATIONAL AND COMMERCIAL FISHERIES..................................... 7-1 

7.1 COMMERCIAL HARVESTS....................................................................... 7-1 

7.2 RECREATIONAL HARVESTS ................................................................... 7-1 

7.3 EFFECTS OF DRILLING DISCHARGES ON HARVEST QUANTITY... 7-2 

7.4 EFFECTS OF DRILLING DISCHARGES ON HARVEST QUALITY...... 7-2 

7.5 SUMMARY................................................................................................... 7-2 

8.0 COASTAL ZONE MANAGEMENT..................................................................... 8-1 

8.1 REQUIREMENTS OF COASTAL ZONE MANAGEMENT...................... 8-1 

8.2 AGENCY INFORMATION.......................................................................... 8-1 

8.3 PROJECT INFORMATION.......................................................................... 8-2 

8.4 PROJECT DESCRIPTION............................................................................ 8-2 

8.4.1 Detailed Description ...................................................................................... 8-2 

8.4.2 Timeline ......................................................................................................... 8-2 

8.4.3 Site Plan ......................................................................................................... 8-2 

8.4.4 Supporting Documentation ............................................................................ 8-3 

8.4.5 Proposed Best Management Practices ........................................................... 8-3 

8.5 PROJECT LOCATION ................................................................................. 8-3 

8.6 CONSISTENCY WITH THE ENFORCEABLE POLICIES OF THE ALASKA 

COASTAL MANAGEMENT PROGRAM .............................................. 8-3 

8.6.1 District Policies.............................................................................................. 8-3 

8.6.2 Alaska Coastal Management Program Standards.......................................... 8-3 

8.7 CONSISTENCY DETERMINATION.......................................................... 8-6 

9.0 MARINE WATER QUALITY CRITERIA .......................................................... 9-1 

9.1 TRACE METALS ......................................................................................... 9-1 

9.1.1 Drilling Fluids................................................................................................ 9-2 

9.1.2 Drilling Cuttings ............................................................................................ 9-3 

9.2 ORGANIC COMPOUNDS ........................................................................... 9-4 

9.3 SUMMARY................................................................................................... 9-5 

10.0 DETERMINATION OF UNREASONABLE DEGRADATION...................... 10-1 

10.1 CRITERION 1 ............................................................................................. 10-1 

10.2 CRITERION 2 ............................................................................................. 10-2 

10.3 CRITERION 3 ............................................................................................. 10-3 

10.4 CRITERION 4 ............................................................................................. 10-5 

10.5 CRITERION 5 ............................................................................................. 10-7 

10.6 CRITERION 6 ............................................................................................. 10-7 

10.7 CRITERION 7 ............................................................................................. 10-8 

10.8 CRITERION 8 ............................................................................................. 10-8 

10.9 CRITERION 9 ............................................................................................. 10-8 

10.10 CRITERION 10 ........................................................................................... 10-8 

11.0 REFERENCES....................................................................................................... 11-1 
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LIST OF FIGURES 

Figure 1-1. Arctic NPDES General Permit Area of Coverage ............................................ A-1 

Figure 3-1. Approximate pattern of initial particle deposition ............................................ A-2 

Figure 4-1. Major Trophic Pathways (Food Web) in the Arctic Regions ........................... A-3 

LIST OF TABLES 

Table 2-1. Eight Generic Drilling Mud Compositions .........................................................B-1 

Table 2-2. Metals Concentrations in Barite Used in Drilling Fluids ....................................B-2 

Table 2-3. Concentration of Organic Pollutants in Three Mineral Oils ..............................B-3 

Table 2-4. Water Quality Data for Drilling Cuttings............................................................B-4 

Table 2-5. Pollutant Concentrations in Untreated Deck Drainage .......................................B-5 

Table 2-6. Quantities of Discharges in Arctic Alaska (1997 – 2003)...................................B-6 

Table 3-1. Summary of Sediment Trace Metal Alterations from Drilling Activities...........B-7 

Table 3-2. Summary Table of the Acute Lethal Toxicity of Drilling Fluid .........................B-8 

Table 3-3. Reported Toxicities of Synthetic-Based Drilling Fluids (LC50s ) .......................B-9 

Table 3-4. OOC Model Input Parameters Held Constant...................................................B-10 

Table 3-5. Summary of OOC Model Results for Open-Water Discharge Test Cases 

Representative of the Arctic NPDES General Permit Area of Coverage .......B-11 

Table 3-6. Estimated Depth of Drilling Muds at the Edge of the Mixing Zone for Open-Water 

Discharge ........................................................................................................B-12 

Table 3-7. Summary of OOC Model Results for Below-Ice Discharge Test Cases Representative 

of the Arctic NPDES General Permit Area of Coverage................................B-13 

Table 3-8. Estimated Depth of Drilling Muds at the Edge of the Mixing Zone for Below-Ice 

Discharge ........................................................................................................B-14 

Table 3-9. Summary of OOC Model Results for Shunting Test Cases ..............................B-15 

Table 3-10. Concentration of Trace Metals in Barite .........................................................B-15 

Table 3-11. Concentrations in Molluscs, Polychaete and Brittle Star Tissues ...................B-16 

Table 3-12. Summary of Metal Bioaccumulation Study Results .......................................B-17 

Table 3-13. Depuration of Metals Bioaccumulated during Exposure to Drilling Fluids or 

Components ....................................................................................................B-20 

Table 4-1. Fishes Located in the Area of Coverage............................................................B-21 

Table 4-2. Shorebirds Located in the Area of Coverage ....................................................B-22 

Table 4-3. Raptors Located in the Area of Coverage .........................................................B-23 

Table 4-4. Seabirds Located in the Area of Coverage........................................................B-24 

Table 4-5. Waterfowl Located in the Area of Coverage.....................................................B-25 

Table 4-6. Summary of ESA Listed Species Occurring Within the Area of Coverage......B-26 

Table 4-7. Summary of Critical Habitat Designations for ESA Listed Species Occurring Within 

the Area of Coverage .....................................................................................B-26 

Table 4-8. Essential Fish Habitat for Species in the Area of Coverage..............................B-27 

Table 9-1. Trace Metal Leach Factors from Barite and Drilling Fluids .............................B-28 

Table 9-2. Soluble and Solids Metals Concentrations........................................................B-28 
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LIST OF TABLES (cont.) 

Table 9-3. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing 

Zone Boundary) to Marine Water Quality Criteria 

 Case 1: Whole mud metal concentration as dissolved metal concentration ..B-29 

Table 9-4. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing 

Zone Boundary) to Marine Water Quality Criteria 

 Case 2: Dissolved metal concentration is two orders of magnitude lower than 

whole mud concentrations .............................................................................B-30 

Table 9-5. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing 

Zone Boundary) to Marine Water Quality Criteria 

 Case 3: Dredged material partition coefficients are used to estimate dissolved metal 

concentrations in whole muds........................................................................B-31 

Table 9-6. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing 

Zone Boundary) to Marine Water Quality Criteria 

 Case 1: Total drilling cutting metal concentration as dissolved metal concentration

........................................................................................................................B-32 

Table 9-7. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing 

Zone Boundary) to Marine Water Quality Criteria 

 Case 2: Dissolved metal concentration is two orders of magnitude lower than 

drilling cutting concentrations .......................................................................B-33 

Table 9-8. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing 

Zone Boundary) to Marine Water Quality Criteria 

 Case 3: Dredged material partition coefficients are used to estimate dissolved metal 

concentrations in drilling cuttings..................................................................B-34 

Table 9-9. Comparison of Sanitary Waste Predicted Total Residual Chlorine Concentrations (at 

Mixing Zone Boundary) to marine Water Quality Criteria ...........................B-35 

APPENDICES 

Appendix A Figures 

Appendix B Tables 

Appendix C NPDES General Permit for Oil and Gas Exploration in the Arctic 

Appendix D Calculation of Solids Deposition Multipliers 

Appendix E Fact Sheet for NPDES General Permit for Oil and Gas Exploration in the Arctic
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ABBREVIATIONS 

AAC Alaska Administrative Code 

ACC Alaska coastal current 

ACMP Alaska Coastal Management Plan 

ADEC Alaska Department of Environmental Conservation 

ADF&G Alaska Department of Fish and Game 

ADNR Alaska Department of Natural Resources 

AO Arctic oscillation 

API American Petroleum Institute 

AWQC Alaska water quality standards 

BAF Bioaccumulation factor 

BMP Best management practice 

BOD Biochemical oxygen demand 

BPT Best Practicable Control Technology Currently Available 

CFR Code of Federal Regulations 

CMF Consumption of marine fish 

CMP Coastal Management Plan 

COD Chemical oxygen demand 

CWA Clean Water Act 

CZMP Coastal Zone Management Plan 

DDT Dichlorodiphenyltrichloroethane 

EA Environmental Assessment 

EC40 Effect concentration to 40% test organisms

EC50 Effect concentration to 50% test organisms

EFH Essential Fish Habitat 

ELG Effluent limitation guidelines 

EOP End of pipe 

EPA USEPA 

ESA Endangered Species Act 

FDA Food and Drug Administration 

FEIS Final Environmental Impact Statement 

FR Federal Register 

GP General permit 

LC50 Lethal concentration to 50% test organisms 

LOEC Lowest observable effect concentration 

MLLW Mean lower low water 

MMS Minerals Management Service 

MZ Mixing zone 

NOAA National Oceanic and Atmospheric Administration 

NOEC No observable effect concentration 

NOEL No observable effect level 

NOI Notice of intent 

NPDES National Pollutant Discharge Elimination System 

OCS Outer Continental Shelf 
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ABBREVIATIONS (cont.) 

ODCE Ocean Discharge Criteria Evaluation 

OOC Offshore Operators Committee 

PAH Polyaromatic hydrocarbons 

PCB Polychlorinated Biphenyls 

PPA Pollution Prevention Act 

QAP Quality assurance plan 

ROC Retention on cuttings 

SBF Synthetic-based drilling fluid 

SPP Suspended particulate phase 

TOC Total organic carbon 

TSS Total suspended solids 

UOD Ultimate oxygen demand 

U.S. United States 

USEPA United States Environmental Protection Agency 

USFWS United States Fish and Wildlife Service 

WBF Water-based drilling fluid 
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UNITS 

ac acres 

bbl barrel 

bbl/day barrels per day 

bbl/h barrels per hour 

°C degrees Celsius 

cm centimeters 

cm/s centimeters per second 

colonies/100 mL colonies per 100 milliliters 

°F degrees Fahrenheit 

fm fathoms 

ft feet 

ft/mi feet per mile 

ft/s feet per second 

g grams 

gal gallons 

g/day grams per day 

g/L grams per liter 

g/mL grams per milliliter 

gpd gallons per day 

h hour 

ha hectares 

in inches 

kg kilograms 

kg/L kilogram per liter 

kg/m3

 kilograms per cubic meter 

km kilometers 

km2 square kilometers 

kn knots 

L liters 

lb pounds 

lb/bbl pounds per barrel 

lb/gal pounds per gallon 

L/h liters per hour 

m meters 

m2 square meters 

mg/cm2 milligram per square centimeter 

mgd million gallons per day 

mg/kg milligram per kilogram 

mg/L milligrams per liter 

m3/h cubic meters per hour 

mi miles 

m/km meters per kilometer 

mL milliliter 

mm millimeter 
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UNITS (cont.) 

m/s meters per second 

nmi nautical miles 

ppm part per million 

ppt part per thousand 

μg/g micrograms per gram 

μg/kg micrograms per kilogram 

μg/L micrograms per liter 

μm micrometers 

v/v volume component per total volume
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1.0 INTRODUCTION 

1.1. PURPOSE OF EVALUATION 

The U.S. Environmental Protection Agency (USEPA) intends to issue a National Pollutant 

Discharge Elimination System (NPDES) general permit for effluent discharges associated with 

oil and gas exploration activities in the Outer Continental Shelf (OCS) areas designated as the 

Beaufort and Chukchi Seas, Hope Basin and Norton Basin Areas of Coverage off northern 

Alaska, as well as all Alaskan state waters contiguous with the OCS areas (Figure 1-1). A copy 

of the general permit is provided in Appendix C. Section 403(c) of the Clean Water Act (CWA) 

requires that NPDES permits for such ocean discharges to be issued in compliance with 

USEPA’s Ocean Discharge Criteria for preventing unreasonable degradation of ocean waters. 

The purpose of this Ocean Discharge Criteria Evaluation (ODCE) report is to identify pertinent 

information and concerns relative to the Ocean Discharge Criteria and exploratory petroleum 

drilling in these waters. 

USEPA’s Ocean Discharge Criteria (40 CFR Part 125, Subpart M) set forth specific 

determinations of unreasonable degradation that must be made prior to permit issuance. 

Unreasonable degradation of the marine environment is defined (40 CFR 125.121[e]) as follows: 

• Significant adverse changes in ecosystem diversity, productivity, and stability of the 

biological community within the area of discharge and surrounding biological 

communities; 

• Threat to human health through direct exposure to pollutants or through consumption of 

exposed aquatic organisms; or 

• Loss of aesthetic, recreational, scientific, or economic values, which are unreasonable in 

relation to the benefit derived from the discharge. 

This determination is to be made based on consideration of the following 10 criteria (40 CFR 

125.122): 

1. The quantities, composition, and potential for bioaccumulation or persistence of 

the pollutants to be discharged; 

2. The potential transport of such pollutants by biological, physical, or chemical 

processes; 

3. The composition and vulnerability of the biological communities which may be 

exposed to such pollutants, including the presence of unique species or 

communities of species, the presence of species identified as endangered or 

threatened pursuant to the Endangered Species Act, or the presence of those 

species critical to the structure or function of the ecosystem, such as those 

important for the food chain; 
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4. The importance of the receiving water area to the surrounding biological 

community, including the presence of spawning sites, nursery/forage areas, 

migratory pathways, or areas necessary for other functions or critical stages in the 

life cycle of an organism; 

5. The existence of special aquatic sites including, but not limited to, marine 

sanctuaries and refuges, parks, national and historic monuments, national 

seashores, wilderness areas, and coral reefs; 

6. The potential impacts on human health through direct and indirect pathways; 

7. Existing or potential recreational and commercial fishing, including finfishing and 

shellfishing; 

8. Any applicable requirements of an approved Coastal Zone Management Plan; 

9. Such other factors relating to the effects of the discharge as may be appropriate; 

10. Marine water quality criteria developed pursuant to Section 304(a)(1). 

If the Regional Administrator determines that the discharge will not cause unreasonable 

degradation of the marine environment, an NPDES permit may be issued. If the Regional 

Administrator determines that the discharge will cause unreasonable degradation of the marine 

environment, an NPDES permit may not be issued. 

If the Regional Administrator has insufficient information to determine, prior to permit issuance, 

that there will be no unreasonable degradation of the marine environment, an NPDES permit will 

not be issued unless the Regional Administrator, on the basis of the best available information, 

determines that: 

• such discharge will not cause irreparable harm to the marine environment during the 

period in which monitoring will take place, 

• there are no reasonable alternatives to the onsite disposal of these materials, and 

• the discharge will be in compliance with certain specified permit conditions (40 CFR 

125.122). 

“Irreparable harm” is defined as “significant undesirable effects occurring after the date of 

permit issuance which will not be reversed after cessation or modification of the discharge” (40 

CFR 125.121[a]). 

1.2. SCOPE OF EVALUATION 

Offshore oil and gas activities can be categorized into exploratory, developmental, and 

production operations. Exploratory drilling operations are conducted from drill barges, jack-up 

rigs, drilling ships, or semi-submersible rigs to identify the location of producing formations. 
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Development operations are conducted on platforms from which multiple wells are drilled after a 

commercially exploitable reserve has been identified. Production operations ensue during and 

after developmental drilling. 

This document evaluates the impacts of waste discharges as provided for by the Arctic NPDES 

general permit proposed for offshore oil and gas exploration in the Beaufort and Chukchi Seas, 

Hope Basin and Northern Norton Basin. Rather than covering a geographic area defined by 

specific State and Federal lease sale tracts, the area of coverage includes the following: federal 

waters of the Beaufort Sea and Chukchi Sea, Hope Basin and Norton Basin planning basins as 

defined by Minerals Management Service (MMS) (see MMS, 2002) and state waters contiguous 

to the landward boundary of the MMS planning basins (Figure 1-1). The “state waters” under 

consideration in this ODCE typically extend from the coastal baseline defined as part of the 

403(c) program to three miles offshore. 

The permit will authorize discharges from exploratory operations in all areas offered for lease by 

MMS and Alaska Department of Natural Resources (ADNR) including past and future lease 

sales within the Beaufort Sea, Chukchi Sea, Hope Basin, and Norton Basin. This method of 

defining the Area of Coverage will insure that all areas potentially leased during the term of this 

general permit will be covered. While the MMS planning basins (i.e., Beaufort Sea, Chukchi 

Sea, Hope Basin and Norton Basin Planning Areas) and contiguous State waters are generally 

larger than the areas offered for lease by MMS and ADNR, discharges under this general permit 

would occur in only those areas ultimately offered for lease. 

This document relies extensively on information provided in the Final Environmental Impact 

Statements (FEIS) for MMS Multiple Lease Sale 186, 195 and 202 (MMS, 2003); the 

Environmental Assessment (EA) for Sale 195 (MMS, 2004a); MMS OCS Reports (MMS, 

2004b, 2005a, 2005b); Final Finding for ADNR Lease Sales in the Beaufort Sea (ADNR, 1999); 

FEIS for MMS Sale 57 (MMS, 1982); USEPA’s guidance documents for oil and gas exploration 

discharges (Avanti Corp., 1993; USEPA, 1985, 1993a, 2000a, 2000b); and the previous ODCE 

for this general permit (USEPA, 1995). Where appropriate, the reader will be referred to these 

publications for more detailed information concerning certain topics. The information presented 

here is a synthesis of these documents, along with the inclusion of discharge modeling results 

and findings published in the scientific literature. 

1.2.1. Beaufort Sea Area of Coverage 

The general permit applies to the entire Beaufort Sea Planning Area (Barrow eastward to the 

Alaska, USA and Yukon, Canada border) including contiguous State waters (Figure 1-1); 

however, for the term of the proposed permit MMS and ADNR will likely only consider leasing 

the areas identified in the MMS 2002 planning area (OCS Lease Sales 186, 195 and 202) and the 

ADNR 1999 area wide lease sale. For purposes of this document and because no additional 

leasing will likely occur outside these and current lease sale boundaries, the area of current leases 

and new leases from MMS Sales BF, 124, 144, 170, 186, 195 and 202 and ADNR 1999 lease 

sale will be considered as the Beaufort Sea Area of Coverage for this ODCE. 
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The Beaufort Sea Planning Area extends from the U.S./Canadian boundary in the Beaufort Sea 

(approximately 141° W) westward to Icy Cape in the Chukchi Sea (16 1° W). It extends about 

260 kilometers (km) [140 nautical miles (nmi)] offshore with water depths ranging from 0 to 

about 1,500 meters (m) [4,921 feet (ft)]. The Beaufort Sea Area of Coverage includes 

approximately 5.58 million hectares (ha) [13.8 million acres (ac)] of the Beaufort Sea Planning 

Area and contiguous State waters (Figure 1-1). 

Five biologically sensitive areas have been identified in the Beaufort Sea, all of which are 

located shoreward of the 10-m isobath. These areas are the Salt Marshes; Harrison Bay/Colville 

River Delta; Thetis Island; Simpson Lagoon; and the Boulder Field. These areas are either 

important feeding grounds for indigenous fish and bird species or, like the Boulder Field, 

comprise unique biological communities. 

Four areas have been proposed as deferral areas for MMS Sales 186, 195 and 202 within the 

Beaufort Sea Area of Coverage. Future lease sale configurations may include or omit these 

areas. The following describes the proposed deferral areas: 

• the Barrow deferral: an area located in the western portion of the proposed sale area 

consisting of 26 whole or partial blocks, approximately 138,000 ac, for protection of 

Barrow subsistence-use zones and wildlife areas; 

• the Nuiqsut deferral: an area located off of Cross Island consisting of 30 whole or partial 

blocks, approximately 162,000 ac, for protection of Nuiqsut subsistence-use zones and 

wildlife areas; 

• the Kaktovik deferral: an area located off of Barter Island consisting of 28 whole or 

partial blocks, approximately 121,000 ac, for protection of the Native Village of 

Kaktovik’s traditional known subsistence-whaling areas; and 

• the Eastern deferral: an area located east of Kaktovik consisting of 60 whole or partial 

blocks, approximately 283,000 ac, adjoining an area that the state of Alaska has deferred 

in recent state sales for the protection of bowhead whales and environment. 

Additionally, ADNR has identified the following areas and time periods as sensitive areas that 

require special consideration when proposing leasing activities: 

• the Boulder Patch in Stefansson Sound, year round; 

• the Canning River Delta, January-December; 

• the Colville River Delta, January-December; 

• the Cross, Pole, Egg, and Thetis Islands, June-December; 

• the Flaxman Island waterfowl use and polar bear denning areas, including the 

Leffingwell Cabin national historic site located on Flaxman Island; 

• the Jones Island Group (Pingok, Spy, and Leavitt Islands) and Pole Island are known 

polar bear denning sites, November-April; 

• the Sagavanirktok River delta, January-December; and 

• Howe Island supports a snow goose nesting colony, May-August. 
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1.2.2. Chukchi Sea Area of Coverage 

The general permit applies to the entire Chukchi Sea Planning Area (Point Hope northward to 

Barrow) including contiguous State waters (Figure 1-1); however, for the term of the proposed 

permit MMS will likely only consider leasing the areas identified in the MMS 2002 planning 

area (Special Interest Sale). There are no current lease sales in the Chukchi Sea by either MMS 

or ADNR. Additionally, ADNR has not proposed any lease offerings in the Chukchi Sea. Since 

the area of MMS Special Interest Sale does not identify the particular lease blocks that may be 

available for sale, the entire MMS Chukchi Sea Planning Area will be considered as the Chukchi 

Sea Area of Coverage for this ODCE. 

The Chukchi Sea Area of Coverage includes approximately 13.76 million ha (34 million ac) 

(Figure 1-1). The Chukchi Sea Area of Coverage extends from Icy Cape westward to Point 

Hope. It extends about 416 km (260 nmi) offshore in water depths ranging from 10 m (32 ft) to 

about 70 m (230 ft). 

The bowhead whale subsistence-hunting area near Barrow in an area of the Chukchi Sea has 

been removed from leasing consideration in the MMS proposed final 5-Year Offshore Oil and 

Gas Leasing Program for 2002-2007. 

1.2.3. Hope Basin Area of Coverage 

The general permit applies to the entire Hope Basin Planning Area (Cape Prince of Whales 

northward to Point Hope) including contiguous State waters (Figure 1-1); however, for the term 

of the proposed permit MMS will likely only consider leasing the areas identified in the MMS 

2002 planning area (Special Interest Sale). There are no current lease sales in the Hope Basin by 

either MMS or ADNR. Additionally, ADNR has not proposed any lease offerings in the Hope 

Basin. Since the area of MMS Special Interest Sale does not identify the particular lease blocks 

that may be available for sale, the entire MMS Hope Basin Planning Area will be considered as 

the Hope Basin Area of Coverage for this ODCE. 

The Hope Basin Area of Coverage includes approximately 16.06 million ha (6.5 million ac) 

(Figure 1-1). The Hope Basin Area of Coverage extends from Point Hope southward to Cape 

Krusenstern (67° N). It extends about 204 km (110 nmi) offshore in water depths ranging from 

10 m (32 ft) to about 70 m (230 ft). 

1.2.4. Norton Sound Area of Coverage 

The general permit applies to the entire Norton Sound Planning Area northward of latitude 64.5° 

N to Cape Prince of Whales including contiguous State waters (Figure 1-1); however, for the 

term of the proposed permit MMS will likely only consider leasing the areas identified in the 

MMS 2002 planning area (Special Interest Sale). There are no current lease sales in the Norton 

Sound by either MMS or ADNR. Additionally, ADNR has not proposed any lease offerings in 
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the Norton Sound. Since the area of MMS Special Interest Sale does not identify the particular 

lease blocks that may be available for sale, the entire MMS Norton Sound Planning Area will be 

considered as the Norton Sound Area of Coverage for this ODCE. 

The Norton Sound Area of Coverage includes approximately 10.12 million ha (25 million) 

(Figure 1-1). The Norton Sound Area of Coverage extends from the Cape Prince of Wales 

southward to Yukon Delta (63°N). It extends about 593 km (320 nmi) offshore in water depths 

ranging from 7.62 m (25 ft) to about 198 m (650 ft). 

The Yukon-Kuskokwim River Delta is considered a vulnerable coastal area which is a critical 

habitat for North America’s largest run of king salmon. Approximately one-third of this delta 

region comprises the Clarence Rhode National Wildlife Refuge. The delta is also critical to 

Native Alaskan Tribes subsistence harvest. 

1.2.5. Duration of Activity 

Ice is present much of the year in the Beaufort and Chukchi seas but drilling can take place yearround in very shallow waters. It is expected that exploratory wells will be drilled from a 

moveable platform resting on the seafloor when ice is not present in these water bodies. An ice 

or gravel island could be constructed to allow drilling to continue during the winter months 

(MMS, 2002; ADNR, 1999). 

In deeper waters, it is likely that drillships or floating platforms anchored to the seafloor would 

be used and drilling would be limited to a short period in the summer months. Also, icebreakers 

could provide support in the vicinity of the drilling rig to control sea ice (MMS, 2002). 

1.3. OVERVIEW OF REPORT 

The evaluation focuses on sources, fate, and potential effects of exploratory drilling rig 

discharges on various groups of aquatic life. The types and projected quantities of discharges are 

detailed in Section 2.0. Anticipated amounts or volumes of wastes, approximate chemical 

composition, and chemical concentrations are also given. 

Following discharge, the fate of the wastes is examined in Section 3.0, which covers dilution, 

dispersion, and persistence of discharged constituents in relation to influential receiving water 

properties, including water depth, ice coverage, currents, wind, and waves. Section 3.0 also 

provides estimates of the vertical and horizontal coverage and deposition of the discharges. This 

information is needed to assess aquatic toxicity and food chain accumulation questions, and the 

probability of burying benthic infaunal invertebrates or otherwise modifying their habitat 

chemically or physically (e.g., via grain size changes). 

An overview of aquatic communities and important species, including threatened and 

endangered species, and potential biological and ecological effects is presented in Section 4.0. 

The means by which drilling mud discharges could impact human health, mainly subsistence, are 

presented in Section 5.0. Section 6.0 provides information on tribal resources other than 
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subsistence that may be affected by this action. Commercial fisheries are discussed in Section 

7.0 and coastal zone management is discussed in Section 8.0. Section 9.0 discusses the 

compliance of expected exploratory drilling discharges with Alaska water quality criteria and 

Section 10.0 summarizes the findings of this report. All figures for this evaluation are presented 

in Appendix A; tables are found in Appendix B. 
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2.0 COMPOSITION AND QUANTITIES OF MATERIALS 

DISCHARGED 

2.1. TYPES OF DISCHARGES FROM DRILLING ACTIVITIES 

This document evaluates the impacts of waste discharges as provided for by the Arctic NPDES 

general permit proposed for offshore oil and gas exploration (i.e., drilling activities). Production 

activities and produced water discharges are not discussed in this document because they are not 

authorized by this permit. 

Oil and gas drilling generates a wide range of waste materials related to the drilling process, 

equipment maintenance, and personnel housing. These materials are commonly discharged 

directly from the drilling rig or platform into the receiving water. The major discharges are 

drilling muds (fluids) and drilling cuttings. Other discharges may include sanitary and domestic 

wastes, desalination unit wastes, boiler blowdown, test fluids, deck drainage, blowout preventer 

fluids, uncontaminated ballast and bilge water, excess cement slurry, non-contact cooling water, 

fire control system test water, and excess cement slurry at the sea floor. 

The major waste streams are those streams with the greatest volumes and amounts of pollutants. 

The major waste streams from drilling operations are drilling fluids, also called drilling mud, and 

drilling cuttings due to their volume and composition. A discussion of drilling fluids and 

cuttings is provided in Section 2.2. The remaining waste streams are miscellaneous waste. 

These are waste streams that are generated in relatively small volume and contain low pollutant 

levels, yet significant enough to be of regulatory concern. Miscellaneous wastes generated from 

drilling operations are deck drainage, domestic and sanitary waste. Section 2.3 discusses these 

waste streams. The remaining waste streams are considered minor wastes and are discussed in 

Section 2.4. 

2.2. DRILLING FLUIDS AND CUTTINGS 

During exploration drilling, drilling fluid (or drilling “mud”) circulates down the bore hole and 

back to the surface, carrying drill cuttings (earthen material) with it. The drill cuttings are 

separated from the drilling fluid on the exploratory vessel and discharged or disposed. The 

processed drilling fluid is then returned to the mud tanks for recirculation to the well. 

Drilling fluid is required in the wellbore to: (1) to cool and lubricate the drill bit; (2) remove the 

rock fragments, or drill cuttings, from the drilling area and transport them to the surface; (3) 

counterbalance formation pressure to prevent formation fluids (i.e. oil, gas, and water) from 

entering the well prematurely, and (4) prevent the open (uncased) wellbore from caving in 

(Berger and Anderson, 1992; Souders, 1998). Drilling fluids are specifically formulated to meet 

the physical and chemical conditions of each particular well site. Therefore, different properties 

may be required of the drilling fluid, depending upon the drilling conditions. For example, a 

higher-density fluid may be needed in high-pressure zones, and a more temperature-resistant 

fluid may be desired in high-temperature conditions. 
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While drilling fluid may be a gas or foam, liquid-based fluids (called drilling muds) are used for 

approximately 93 percent of wells (API, 1997). In addition to liquid, drilling muds usually 

contain bentonite clay that increases the viscosity and alters the density of the fluid. Drilling 

mud may also contain additional additives that alter the properties of the fluid. The most 

significant additives are described later in this section. The American Petroleum Institute (API) 

environmental guidance document “Waste Management in Exploration and Production 

Operations,” (API E5) considers the three general categories of drilling fluid (muds) to be waterbased, oil-based, and synthetic-based. Synthetic-based muds are used as substitutes for oil-based 

muds, but also may be an advantageous replacement for water-based muds in some situations. 

Water-based muds are used most frequently. The base is salt water for offshore wells. The 

primary benefit of water-based muds is cost; they are the least expensive of the major types of 

drilling fluids, and in general they are less expensive to use since the resultant drilling waste can 

be discharged onsite provided these wastes pass regulatory requirements (USEPA, 1999a). The 

significant drawback with water-based muds is their limited lubricity and reactivity with some 

shales. In deep holes or high-angle directional drilling, water-based muds are not able to supply 

sufficient lubricity to avoid sticking of the drill pipe. Reactivity with clay shale can cause the 

destabilization of the wellbore. In these cases, oil-based and synthetic muds are needed. 

In 1993, EPA estimated that about 15 percent of wells drilled deeper than 10,000 feet used some 

oil-based muds (USEPA, 1993b). Oil-based muds are composed primarily of diesel oil or 

mineral oil and are therefore more expensive than water-based muds. This higher cost, which 

includes the added burden of removing the oil from drill cuttings, and the required disposal 

options make oil-based muds a less frequently used option. Oil-based muds are well suited for 

the high temperature conditions found in deep wells because oil components have a higher 

boiling point than water, and oil-based muds can avoid the pore-clogging that may occur with 

water-based muds. Also oil-based muds are used when drilling through reactive (or high 

pressure) shales, high-angle directional drilling, and drilling in deep water. These situations 

encountered while drilling can slow down the drilling rate, increase drilling costs or even be 

impossible if water-based muds are used. In cases when oil-based muds are necessary, the upper 

section of a well generally is drilled with water-based muds and the conversion is made to oilbased mud when the situation requires it. It is predicted that since the industry trend is toward 

deeper wells, oil-based muds may become more prominent. However, because oil-based muds 

and their cuttings can not be discharged this may not be the case. 

Since about 1990, the oil and gas extraction industry has developed many new oleaginous (oillike) base materials from which to formulate high performance drilling fluids. A general class of 

these fluids is called synthetic materials, such as the vegetable esters, poly alpha olefins, internal 

olefins, linear alpha olefins, synthetic paraffins, ethers, linear alkylbenzenes, and others. Other 

oleaginous materials have also been developed for this purpose, such as enhanced mineral oils 

and non-synthetic paraffins. Industry developed synthetic-based fluids with these synthetic and 

non-synthetic oleaginous materials as the base fluid to provide the drilling performance 

characteristics of traditional oil-based fluids based on diesel and mineral oil, but with the 

potential for lower environmental impact and greater worker safety through lower toxicity, 

elimination of polyaromatic hydrocarbons (PAH), faster biodegradability, lower bioaccumulation 
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potential and in some drilling situations decreased drilling waste volume (FR 66086, December 

16, 1996). 

Drilling muds typically have several additives. The following is a list of the more significant 

additives: 

• Weighting materials, primarily barite (barium sulfate), may be used to increase the 

density of the mud in order to equilibrate the pressure between the wellbore and 

formation when drilling through particularly pressurized zones. Hematite (Fe2O3) 

sometimes is used as a weighting agent in oil-based muds (Souders, 1998). 

• Corrosion inhibitors such as iron oxide, aluminum bisulfate, zinc carbonate, and zinc 

chromate protect pipes and other metallic components from acidic compounds 

encountered in the formation. 

• Dispersants, including iron lignosulfonates, break up solid clusters into small particles 

so they can be carried by the fluid. 

• Flocculants, primarily acrylic polymers, cause suspended particles to group together so 

they can be removed from the fluid at the surface. 

• Surfactants, like fatty acids and soaps, defoam and emulsify the mud. 

• Biocides, typically organic amines, chlorophenols, or formaldehydes, kill bacteria that 

may produce toxic hydrogen sulfide gas. 

• Fluid loss reducers include starch and organic polymers and limit the loss of drilling 

mud to under-pressurized or high-permeability formations (USEPA, 1987). 

2.2.1. Number and Types of Exploratory Wells 

The types of wells that may be drilled under this permit include exploration wells and delineation 

wells. An exploration well is a well that is drilled into a previously undrilled or noncommercial 

trap to test for the presence of a new hydrocarbon accumulation. A delineation well is a well that 

is drilled at a distance from a discovery well to determine the physical extent, reserves and likely 

production rate of a new oil or gas field. The following sections describe the number of each 

type of well that may be drilled during the effect of the Arctic NPDES general permit. 

2.2.1.1. Beaufort Sea 

Since it is not known the exact number of each type of well that will be drilled from new leases 

in the Beaufort Sea Area of Coverage during the effect of this permit (i.e., 2006-2011), they have 

been estimated for this evaluation from historical data, the MMS FEIS for Lease Sales 186, 195, 
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and 202 (MMS, 2003, 2004a), and the ADNR 1999 Lease Sale (ADNR, 1999). Activities on the 

leases could extend over a period of 25 to 40 years. 

Based on historical exploration well data since 1960 (ADNR, 1999), 31 wells have been drilled 

in federal waters of the Beaufort Sea and 401 have been drilled under State leases for the North 

Slope (both onshore and offshore). While the number and type of exploratory wells that may be 

drilled in State waters has not been estimated in ADNR’s lease offering, it can be estimated from 

historical trends (ADNR, 1999, Figure 5.3) that 5-10 wells will be drilled each year from 

exploration activities in the North Slope of which only a small fraction, maybe 1-2 wells, will be 

drilled offshore. The percent of these wells that has resulted in discovery is 13.2 percent. 

Therefore, it is estimated that 10 exploration wells and one delineation well will be drilled in 

State waters under this permit. 

Exploratory drilling for Lease Sale 186 is expected to continue through 2009 with delineation 

wells drilled through 2010. It is estimated that a total of six exploration wells and six delineation 

wells will be drilled over this period (MMS, 2003) and approximately six exploration wells and 

six delineation wells will be drilled during the permit period. 

Exploratory drilling for the areas covered under Lease Sale 195 is expected to begin in 2007 and 

continue until 2013, with delineation wells drilled through 2014. It is estimated that a total of six 

exploration wells and six delineation wells will be drilled over this period (MMS, 2003) and 

approximately four exploration wells and four delineation wells will be drilled during the permit 

period. 

Exploratory drilling for the areas covered under Lease Sale 202 is expected to begin in 2010 and 

continue until 2018, with a total of six exploration and five delineation wells expected to be 

drilled over this period (MMS 2003). It is expected that one exploration well and one 

delineation well will be drilled during this permit period. 

In summary, it is estimated that a total of 21 exploration wells and 12 delineation wells will be 

drilled in the Beaufort Sea under the effective period of this general NPDES permit. 

2.2.1.2. Chukchi Sea 

Since it is not known the exact number of each type of well that will be drilled from new leases 

in the Chukchi Sea Area of Coverage during the effect of this permit (i.e., 2006-2011), they have 

been estimated for this evaluation from the FEIS for the Outer Continental Shelf Oil and Gas 

Leasing Program: 2002-2007, which includes Chukchi Sea Area Lease Sales 193 and 203 

(MMS, 2002). These two lease sales exclude nearshore tracts, the Chukchi Polynya, and tracts 

near Barrow. It is estimated that a total of 6 to 24 exploration and delineation wells will be 

drilled during the life of these leases. It is expected that approximately 2 exploration wells and 2 

delineation wells will be drilled at Lease Sale 193 and no exploration or delineation wells will be 

drilled at Lease Sale 203 during the period of this permit. 
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2.2.1.3. Hope Basin 

It is expected that no exploration or delineation wells will be drilled during the period of this 

permit based on the information provided in the MMS FEIS for the OCS Oil and Gas Leasing 

Program (2002-2007). 

2.2.1.4. Norton Sound 

It is expected that no exploration or delineation wells will be drilled during the period of this 

permit based on the information provided in the MMS FEIS for the OCS Oil and Gas Leasing 

Program (2002-2007). 

2.2.2. Control of Discharge 

The permit incorporates the effluent limitations required by the effluent limitation guidelines 

(ELGs) in 40 CFR 435, Subpart A, which apply to drilling fluids and cuttings. Additionally, the 

permit incorporates an end-of-pipe whole effluent toxicity limit of a minimum 96-hour LC50 of 

30,000 parts per million (ppm) suspended particulate phase (SPP) on discharged drilling fluids. 

This limit is a technology-based control on toxicity, as well as toxic and nonconventional 

pollutants. The 30,000 ppm SPP limitation is based upon the Agency's evaluation that it 

constitutes an economically and technically achievable level of performance and is both 

technologically feasible and economically achievable and reflects BAT level of control (USEPA, 

1993a) on a national basis. Before promulgation of the guideline, this criterion has been used by 

USEPA, Region 10 in evaluating the case-by-case mud discharge authorizations. 

2.2.3. Composition of Drilling Fluids 

Traditional water-based drilling fluids (drilling muds) have water or a water miscible fluid as the 

continuous phase and the suspending medium for solids. They are composed of a complex 

mixtures of clays, barite, and specialty additives used primarily to remove rock particles from the 

hole created by the drill bit. The composition of drilling mud can vary over a wide range from 

one hole to the next, as well as during the course of drilling a single hole when encountering 

different formations. Table 2-1 shows the formulations for eight generic muds; concentration 

ranges account for the variability in the environment (e.g., drilling formations). 

Synthetic-based drilling fluids are a subset of non-aqueous drilling fluids, i.e., those which have 

a water-immiscible fluid, such as an oleaginous (oil-like) material as the continuous phase. 

Synthetic-based drilling fluids include vegetable esters, poly alpha olefins, internal olefins, linear 

alpha olefins, synthetic paraffins, ethers, linear alkyl benzenes, and others (USEPA, 1999b). 

Based on data provided by the American Petroleum Institute, typical synthetic-based drilling 

fluids have a formulation consisting of 47 percent by weight synthetic-based drilling fluid, 33 

percent solids, and 20 percent water (Baker-Hughes Inteq as cited in USEPA, 1999b). 
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2.2.3.1. Barite 

Barite is the principal weighting agent of both water-based drilling muds and synthetic-based 

drilling fluids. Barite is mostly barium sulfate, which is 59 percent barium by weight. Barite is a 

naturally occurring mineral, is readily available and inexpensive, and is characterized by high 

specific gravity [4.1 to 4.3 grams per milliliter (g/mL)], low water solubility (0.03 ppm in 

seawater), low Mohs’ hardness (2.5 – 3.5), and chemical inertness. As shown in Table 2-1, 

barite concentrations in drilling fluids can range from 25 to 450 pounds per barrel (lb/bbl). 

2.2.3.2. Metals 

The presence of potentially toxic trace elements in drilling fluids and adhering to cuttings is a 

major concern. Barite is a mineral composed of barium sulfate and is known to have trace 

contaminants of several toxic heavy metals such as mercury, cadmium, arsenic, chromium, 

copper, lead, nickel, and zinc (USEPA, 1999b). In order to control the concentration of heavy 

metals in drilling fluids, EPA promulgated regulations applicable to the offshore subcategory of 

the oil and gas industry in 1993 (40 CFR Part 435, Subpart A) requiring that stock barite meet 

the maximum limitations of 3 mg/kg for cadmium and 1 mg/kg for mercury. Table 2-2 presents 

the metals concentrations in so-called “clean” barite that were the basis for the cadmium and 

mercury limitations in the offshore rule. 

Drill pipe dope (which is known to contain 15 percent copper and 7 percent lead), and drill collar 

dope (which can contain 35 percent zinc, 20 percent lead, and 7 percent copper), may also 

contribute trace metals to the muds and cuttings discharge. 

2.2.3.3. Specialty Additives 

Specialty additives to drilling fluids include a wide variety of substances, ranging from simple 

inorganic salts to the complex polymers associated with synthetic-based drilling fluids. Among 

the additives used in large enough quantities to result in significant mass loadings to the 

environment are spotting materials, lubricants, zinc compounds, and materials added to prevent 

loss of circulation. Variation in metal concentrations has been attributed to the addition of 

authorized specialty additives, variations in base mud components (i.e., chrome-free 

lignosulfonate replacing chrome-containing lignosulfonate), incidental contamination from pipe 

dope, and possibly to differences in laboratory analyses and sample sources. 

2.2.3.4. Spotting Compounds

Spotting compounds are used to help free stuck drill strings. Some of these (e.g., vegetable oil or 

fatty acid glycerol) are easily broken down in the environment. The most effective and, 
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consequently, most frequently used compounds are oil-based. The discharge of muds and 

cuttings contaminated by diesel oil or diesel oil spots or “pills” is prohibited by this permit. 

A concentrated pill of the spotting agent is pumped downhole and up the annual space between 

the borehole and drill pipe. After working to free the stuck pipe the pill is then pumped back to 

the surface. The discharge of residual amounts of mineral oil pills was authorized in recent 

permits provided that the mineral oil pill and at least a 50 barrel buffer of drilling fluids on both 

sides of the pill is removed from the system and not discharged. The residual mineral oil content 

cannot exceed 2 percent (v/v). 

Mineral oils can contribute potentially toxic organic pollutants to drilling muds to which they are 

added. These data show that the concentration of organic pollutants in the drilling muds is 

roughly proportional to the amount of mineral oil added. Table 2-3 presents the chemical 

analyses of three different mineral oils (Battelle, 1984). Alkylated biphenyls were detected in all 

three mineral oils; naphthalene, fluorene, phenanthrene, alkylated benzenes, alkylated 

naphthalenes, alkylated fluorenes, alkylated phenanthrenes, alkylated biphenyls, and alkylated 

dibenzothiaphenes were detected in one or more of the oils. Naphthalene is the only one of the 

individual compounds detected for which Federal marine water quality criteria exist. 

2.2.3.5. Lubricants 

Lubricants are added to the drilling mud when high torque conditions are encountered on the 

drill string. These can be vegetable, paraffinic, or asphaltic-based compounds such as Soltex. 

When needed, these lubricants are used to treat the entire mud system [roughly 32,000 liters (L) 

or 8,453 gallons (gal)] and are discharged into receiving waters along with the muds. This can 

result in a 746-1,493 kilograms (kg) [1,650-3,300 pounds (lb)] mass loading of the substances 

into the environment for each treatment of the system. Mineral oils, mentioned above, may also 

be used as lubricants and may, therefore, contribute to organic pollutant loading. 

2.2.3.6. Zinc Carbonate 

Zinc carbonate is used as a sulfide scavenger when formations containing hydrogen sulfide are 

expected to be encountered during drilling. Typically the entire mud system is treated with zinc 

carbonate to achieve mud concentrations of zinc between 1.5 and 5.5 kilograms per cubic meter 

(kg/m3

) [0.01-0.05 pounds per gallon (lb/gal)], resulting in 240-940 kg (520-2,080 lb) of zinc in 

the mud system. The zinc sulfide and unreactive zinc compounds are discharged with the 

drilling mud into the environment, thus contributing to the overall loading of zinc. 
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2.2.3.7. Other Materials 

In cases when circulation of the mud system is lost, combinations of cellophane, mica, and 

walnut hulls, or other inert substances such as vegetable and polymer fibers, flakes, granules, and 

glass or plastic spheres may be added to the mud in one of two methods. The entire system can 

be treated with typically 0.2 to 2.0 kg (0.5-5.0 lb) per barrel (bbl) of mud, which results in 220 to 

2,200 kg (1,000 to 10,000 lb) of additives to the system. Alternatively, a pill of 15,899-31,797 L 

(4,200- 8,400 gal) containing 57-170 grams per liter (g/L) of additive (0.5-1.4 lb/gal) can be sent 

downhole. When drilling resumes, the additives are separated from the drilling muds by 

screening and discharged into the environment along with the cuttings. 

2.2.4. Composition of Drilling Cuttings 

Only very limited data are available on the physico-chemical characteristics of drilling cuttings, 

mostly from the Georges Bank program and CENTEC (1984) analysis of three sets of drilling 

cuttings from three different wells, all at depths greater than 10,000 ft. Washing of drilling 

cuttings has some effect on the physical properties, but has no noticeable affects on the metals 

content. Available conventional, metals, and organic water quality data for drilling cuttings is 

provided in Table 2-4. 

2.2.5. Quantity Discharged 

2.2.5.1. Rate of Discharge During Well Operation 

The discharge rate of drilling fluids (muds) and cuttings during well drilling operations is quite 

variable. Drilling fluids are separated from the drill cuttings on the exploratory vessel and reused 

in the wellbore. The volume of rock cuttings produced from drilling is primarily a function of 

the depth of the well and the diameter of the wellbore. It has been estimated that between 0.2 bbl 

and 2.0 bbl (8.4 and 84.0 gal) of total drilling waste are produced for each vertical foot drilled 

(USEPA, 1987). 

Each exploratory and delineation well in the Beaufort Sea Area of Coverage is expected to 

produce about 255 bbl of drilling muds and 1,520 bbl of drill cuttings (MMS, 2002). 

Approximately 565 bbl of drilling muds and 1,970 bbl of drill cuttings (MMS, 2002) are 

expected to be produced by each exploratory and delineation well in the Chukchi Sea Area of 

Coverage. There are no estimates of discharge rates for the Hope Basin and Norton Sound Area 

of Coverage since it is not predicted that any wells will be drilled in these areas. Additionally, 

ADNR has not estimated discharge rates for discharge to State waters. Therefore, the MMS 

discharge rates are used to estimate the quantity of drilling fluids and cuttings discharged under 

this general permit. 
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It is estimated that 90 percent of the wells drilled will use water-based drilling fluids. For 

drilling depths of 7,000 ft, it is assumed that 80 percent of the water-based drilling muds will be 

recycled and the remaining “spent mud” will be discharged at the exploration site. All of the 

cuttings would be discharged at the exploration site (MMS, 2003). 

 

Based on the relatively shallow water depths in the area of permit coverage, an estimated 10 

percent of wells drilled in the U.S. are assumed to use synthetic-based drilling fluids (USEPA, 

1999b). Synthetic-based drilling fluids are prohibited from being discharged in bulk and are 

considered to be a valuable commodity rather than a waste regardless of whether they are used or 

unused (USEPA, 1999b). Thus, they are generally reused in drilling operations and discharged 

only as a contaminant attached to drill cuttings, known as retention on cuttings (ROC). 

2.2.5.2. Estimated Quantity Discharged 

2.2.5.2.1. Beaufort Sea 

Under the current permit (1995-2005), 1,086-11,399 bbl drilling fluids and cuttings were 

discharged on a monthly average with a total 29,151 bbl based on discharge monitoring reports. 

Individual discharge values are provided in Table 2-6. Lease Sales 186 and 195 are expected to 

produce about 1,040 dry short tons of dry drilling mud and 6,300 dry short tons of cuttings per 

sale (MMS, 2003). Lease sale 202 is expected to produce 935 dry short tons of dry drilling mud 

and 5,775 dry short tons of cuttings per sale (MMS, 2003). 

MMS lease sales are estimated to produce a total of 5,610 bbl drilling mud and 33,440 bbl drill 

cuttings while ADNR lease sales are estimated to produce 2,475 bbl of dry drilling mud and 

16,720 bbl of drill cuttings. This would result in a total discharge of 8,085 bbl drilling mud and 

50,160 bbl drill cuttings in the Beaufort Sea Area of Coverage under this general permit. 

2.2.5.2.2. Chukchi Sea 

MMS lease sales are estimated to produce a total of 2,260 bbl drilling mud and 7,880 bbl drill 

cuttings. Due to the fact that there are no current operating leases in the Chukchi Sea, no 

estimate is available for the amount of drilling muds and cuttings expected to be discharged in 

contiguous State waters due to future exploratory oil and gas exploration. 

2.2.5.2.3. Hope Basin 

Due to the fact that there are no current operating leases in the Hope Basin, no estimate is 

available for the amount of drilling muds and cuttings expected to be discharged in the Hope 

Basin or contiguous State waters due to future exploratory oil and gas exploration. 
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2.2.5.2.4. Norton Sound 

Due to the fact that there are no current operating leases in Norton Sound, no estimate is 

available for the amount of drilling muds and cuttings expected to be discharged in Norton 

Sound or contiguous State waters due to future exploratory oil and gas exploration. 

2.2.6. Summary 

There are three general categories of drilling fluid (muds) water-based, oil-based, and syntheticbased. Water-based muds are used most frequently because it is the least expensive. Oil-based 

muds are composed primarily of diesel oil or mineral oil, but result in lower volumes of waste 

discharge. Synthetic-based fluids provide the drilling performance characteristics of oil-based 

fluids, but have less environmental impact due to lower toxicity, elimination of PAH, faster 

biodegradability, lower bioaccumulation potential, and, in some drilling situations, decreased 

drilling waste volume. 

The types of wells that may be drilled under this permit include exploration wells and delineation 

wells. It is estimated that 21 exploration wells and 12 delineation wells will be drilled in the 

Beaufort Sea Area of Coverage and 2 exploration wells and 2 delineation wills will be drilled in 

the Chukchi Sea Area of Coverage. No exploration wells or delineation wells are expected to be 

drilled in the Hope Basin or Norton Sound Areas of Coverage. 

Components of concern in drilling fluids include trace metals and specialty additives used with 

generic and synthetic-based drilling mud systems. The majority of trace metals will remain 

bound to particulates in the whole mud. Specialty additives could be a source of trace metals 

(e.g., zinc) and petroleum hydrocarbons. Mass loadings of the additives depend on the 

concentrations, frequency of usage, and conditions encountered during the drilling. 

It is estimated that 8,085 bbl drilling muds and 50,160 bbl drill cuttings will be discharged in the 

Beaufort Sea Area of Coverage and 2,260 bbl drilling mud and 7,880 bbl drill cuttings will be 

discharged in the Chukchi Sea Area of Coverage. No estimate is available for the amount of 

drilling muds and cuttings expected to be discharged in the Hope Basin, Norton Sound or 

contiguous State waters due to future exploratory oil and gas exploration. 

2.3. MISCELLANEOUS DISCHARGES 

There are three exploration discharges associated drilling wastes which are a relatively small but 

significant category of waste from the oil and gas extraction industry are deck drainage, sanitary 

waste and domestic waste. Because of their nature, these waste streams are the most likely to 

contain constituents of concern. The following paragraphs provide a discussion of each of these 

discharges. 
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2.3.1. Deck Drainage 

Deck drainage refers to any waste resulting from platform washing, deck washing, spillage, 

rainwater, and runoff from curbs, gutters, and drains, including drip pans and wash areas. This 

could also include pollutants, such as detergents used in platform and equipment washing, oil, 

grease, and drilling fluids spilled during normal operations. 

Deck drainage occurs when water from rainfall or from equipment cleaning comes in contact 

with oil-coated surfaces; the water becomes contaminated and must be treated and disposed. Oil 

and grease are the primary pollutants identified in the deck drainage wastestream (USEPA, 

1993a). In addition to oil, various other chemicals used in drilling operations may be present in 

deck drainages. The chemicals may include drilling fluids, ethylene glycol, lubricants, fuels, 

biocides, surfactants, detergents, corrosion inhibitors, cleaners, solvents, paint cleaners, bleach, 

dispersants, coagulants, and any other chemical used in the daily operations of the facility 

(Dalton, Dalton, & Newport, 1985). 

2.3.1.1. Characteristics of Untreated Deck Drainage 

Untreated deck drainage can contain oil and grease in quantities ranging from 12 to 1,310 

milligrams per liter (mg/L). Ranges for other pollutant quantities in untreated deck drainage are 

provided in Table 2-5. 

2.3.1.2. Control and Treatment Technology 

The major factors in the performance of control and treatment technology are salt content, solid 

content, chemical content, oil content, temperature, oil density, oil viscosity and wax content, 

and oil droplet size (USEPA, 1993a). A typical facility is equipped with drip pans and gutters to 

collect deck and drilling flow drainage. The drainage is collected in a sump where the water and 

oil are separated by a gravity separation process. Oil in the sump tank is recovered and 

transferred to shore via pipeline or reinjected to the formation. The water from the sump is 

discharged to the ocean via a skim pile. Skim piles remove that portion of oil which quickly and 

easily separates from water. They are constructed of large diameter pipes containing internal 

baffled sections and an outlet at the bottom. During the period of no flow, oil will rise to the 

quiescent areas below the underside of inclined baffled plates where it coalesces. Due to the 

differences in specific gravity, oil floats upward through oil risers from baffle to baffle. The oil 

is collected at the surface and removed by a submerged pump. These pumps operate 

intermittently and will move the separated oil to a sump tank. 
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2.3.1.3. Estimated Quantity Discharged 

Deck drainage discharges are not continuous discharges and they vary significantly in volume. 

At times of platform washdowns, the discharges are of relatively low volume and are anticipated. 

During rainfall events, very large volumes of deck drainage may be discharged in a very short 

period of time. Deck drainage is a concern particularly in areas with high precipitation; 

however, the low Arctic temperatures prevent high volumes of deck drainage since operations 

occur mainly in the winter months and precipitation drainage is expected to occur only during 

summer months. Under the current permit, discharge quantities varied from 12 to 78,193 gallons 

per day (gpd) (Individual discharge values are provided in Table 2-6.). While it is expected that 

only small quantities (less than 300 gpd) of deck drainage would occur during the effective 

period of this permit, it is possible that higher quantities (~75,000 gpd) may occur as shown by 

past discharges. This general permit requires the facilities to report total quantity discharged 

rather than flow rates to provide a more adequate future analysis of deck drainage quantities 

discharged. 

2.3.2. Sanitary and Domestic Waste 

While some platforms discharge sanitary and domestic wastes separately, many combine these 

waste streams prior to discharge. Therefore, this section will discuss sanitary waste, domestic 

waste and the combined waste. Sanitary waste is human body waste discharged from toilets and 

urinals. It consists of secondary treated chlorinated effluent. Domestic waste (gray water) refers 

to materials discharged from sinks, showers, laundries, safety showers, eyewash stations, and 

galleys. Gray water can include kitchen solids, detergents, cleansers, oil and grease. Domestic 

waste also includes solid materials such as paper and cardboard which must be disposed of 

properly. Domestic waste is sometimes reused to make drilling mud rather than being 

discharged directly into receiving waters. 

2.3.2.1. Characteristics of Sanitary and Domestic Wastes 

The concentration of sanitary wastes varies widely with time, occupancy, platform 

characteristics and operational situation. Pollutants of concern in untreated sanitary waste 

include biochemical oxygen demand (BOD), total suspended solids (TSS), coliform, and residual 

chlorine. Typical concentrations of these pollutants in treated effluent are 30 mg/L, 40 mg/L, 

180 colonies per 100 milliliters (colonies/100 mL) and 1.7 mg/L, respectively (USEPA, 1993a). 

Pollutants of concern with untreated domestic waste include BOD and TSS. Typical 

concentrations of these pollutants in treated effluent are 195 and 140 mg/L, respectively 

(USEPA, 1993a). 
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2.3.2.2. Control and Treatment Technology 

There are two alternatives to handling of sanitary wastes from offshore facilities. The wastes can 

be treated at the offshore location or they can be retained and transported to shore facilities for 

treatment. Due to remote areas of operation and storage limitations, most offshore facilities 

usually treat and discharge sanitary wastes at the source. The treatment systems presently in use 

may be categorized as physical/chemical and biological. 

It is often necessary to utilize macerators with domestic wastes to prevent the release of floating 

solids. Chlorination is not necessary since these wastes do not contain coliforms. Additionally, 

the permit prohibits the discharge of foam and garbage. 

The NPDES permit controls these discharges as follows: 

• BOD and TSS must have an average monthly concentration less than 30 mg/L, an 

average weekly concentration less than 45 mg/L and a maximum daily average 

concentration less than 60 mg/L. 

• Coliform counts must be less than 200 colonies/100 mL on a daily basis and 100 

colonies/100 mL on an average monthly basis. 

• Chlorine residual concentrations must be less than 1.0 mg/L in Federal waters and in 

State waters when a mixing zone is authorized, and less than 0.0075 mg/L within State 

waters when no mixing zone is authorized. 

• Sanitary and domestic wastes within State waters are limited to 2,500 gpd per rig. There 

is no limit on the quantity of sanitary and domestic wastes in Federal waters. 

2.3.2.3. Estimated Quantity Discharged 

The volume of sanitary wastes varies widely with time, occupancy, platform characteristics, and 

operational situation. Discharge of sanitary waste from an Alaskan offshore oil rig is usually less 

than 600 gpd based on discharge monitoring reports. Individual discharge values are provided in 

Table 2-6. 

The volume of domestic waste discharged has been estimated to range from 50 to 100 gal per 

person per day (USEPA, 1993a). Discharge of domestic waste from an Alaskan offshore oil rig 

is usually less than 6,000 gal per day based on discharge monitoring reports. Individual 

discharge values are provided in Table 2-6. 

Combined sanitary and domestic waste discharge rates of 868 to 75,150 gpd have been reported 

for Arctic Alaska platforms based on discharge monitoring reports. Individual discharge values 

are provided in Table 2-6. It is estimated that discharges of sanitary and domestic wastes will be 

less than 6,000 gpd per rig for the effective period of this permit. 
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2.4. MINOR DISCHARGES 

The term “minor” discharges is used to describe all point sources originating from offshore oil 

and gas drilling operations other than drilling fluids, drill cuttings, deck drainage, and sanitary 

and domestic wastes. The following sections identify these discharges followed by a brief 

description. 

2.4.1. Blowout Preventer Fluid 

The blowout preventer is a device designed to contain pressures in the well that cannot be 

contained by the drilling mud. It may be located on the sea floor or on the drilling platform and 

is designed to maintain the pressure in the well that cannot be controlled by the drilling mud. 

Fluid on the blowout preventer may be discharged in small quantities when the blowout 

preventer is actuated on the hydraulic equipment, usually during testing of the blowout preventer 

device. Generally, this may occur on a weekly basis. The general permit prohibits the discharge 

of free oil in this waste stream. 

The primary constituents of blowout preventer fluid are oil (vegetable or mineral) or an 

antifreeze solution (ethylene glycol and water). The volume of blowout preventer fluid 

discharge has been estimated to range from 67 to 314 bbl/day (USEPA, 1993a). It is estimated 

that discharges of blowout preventer fluid will be less than 325 bbl/day, when discharged. This 

general permit requires the facilities to report total quantity discharged rather than flow rates to 

provide a more adequate future analysis of blowout preventer fluid quantities discharged. 

2.4.2. Desalination Unit Waste 

Desalination Unit Waste is wastewater, residual high-concentration brine, associated with the 

processes, distillation or reverse osmosis units, used in creating freshwater from seawater. The 

concentrate is similar to sea water in chemical composition; however, anions and cations 

concentrations are higher. The general permit prohibits the discharge of free oil in this waste 

stream. 

Discharge from desalination units may vary greatly depending on the freshwater needs of the rig. 

Under the current permit, discharge quantities varied from 174 to 140,000 gpd based on 

discharge monitoring reports; individual discharge values are provided in Table 2-6. It is 

estimated that discharges from the desalination unit will be less than 140,000 gallons per day per 

rig. Additives discharged with desalination wastes include cleanser (up to 330 gal/month), water 

purifier (up to 2 gal/month), and acidifier/scale remover (up to 15 lb/month). This general 

permit requires the facilities to report total quantity discharged rather than flow rates to provide a 

more adequate future analysis of desalination unit waste quantities discharged. 
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2.4.3. Fire Control System Test Water 

Fire control system test water is sea water that is released during the training of personnel in fire 

protection, and the testing and maintenance of fire protection equipment on the platform. This 

test water may be treated with a biocide. Recommended dosages are very situation-dependent 

and can vary from 1.0 to as high as 1,200 ppm. There are, however, little or no quantitative data 

on biocide concentrations in this discharge. There are, however, little or no quantitative data on 

biocide concentrations in this discharge. 

Under the current permit, discharge quantities varied from 43 to 360 gpd based on discharge 

monitoring reports; individual discharge values are provided in Table 2-6. Therefore, it is 

estimated that discharges of fire control system test water will be less than 360 gpd when 

discharged. This general permit requires the facilities to report total quantity discharged rather 

than flow rates to provide a more adequate future analysis of fire control system test water 

quantities discharged. The general permit also requires the permittee to provide an annual 

inventory of the type (product name) and quantity of biocides and chemicals (other than water or 

seawater) added to this discharge. Additionally, the general permit prohibits the discharge of 

free oil in this waste stream. 

2.4.4. Non-Contact Cooling Water 

Non-contact cooling water is sea water that is used for non-contact, once-through cooling of 

various pieces of machinery (e.g., power generators) on the platform. Biocides can be used to 

control biofouling in heat exchanger units. Recommended dosages are very situation-dependent 

and can vary from 1.0 to as high as 1,200 ppm. There are, however, little or no quantitative data 

on biocide concentrations in this discharge. 

 

The volume of non-contact cooling water required for drilling operations can vary depending on 

the system used. Discharges of non-contact cooling water from an Alaskan offshore oil rig is 

approximately 210,000 gpd based on discharge monitoring reports. Individual discharge values 

are provided in Table 2-6. Therefore, it is estimated that discharges of non-contact cooling water 

will be less than 210,000 gpd when discharged. This general permit requires the facilities to 

report total quantity discharged rather than flow rates to provide a more adequate future analysis 

of non-contact cooling water quantities discharged. The general permit also requires the 

permittee to provide an annual inventory of the type (product name) and quantity of biocides and 

chemicals (other than water or seawater) added to this discharge. Additionally, the general 

permit prohibits the discharge of free oil in this waste stream. 

2.4.5. Ballast Water 

Uncontaminated ballast water is seawater added or removed to maintain the proper ballast floater 

level and ship draft. It may be contaminated with oil, but usually can be discharge without 

treatment. Oily water can either be treated through the oil/water separation process or with a 
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small amount of dissolved aromatic constituents through molecular diffusion at the oil-water 

surface prior to discharge. The general permit prohibits the discharge of any materials that may 

cause a visible sheen of oil. 

Under the current permit, discharge quantities varied from 40 to 2,254,000 gpd based on 

discharge monitoring reports; individual discharge values are provided in Table 2-6. Therefore, 

it is estimated that discharges of ballast water during the effective period of this permit will be 

highly variable, but less than 2.5 million gallons per day (mgd). This general permit requires the 

facilities to report total quantity discharged rather than flow rates to provide a more adequate 

future analysis of ballast water quantities discharged. 

2.4.6. Bilge Water 

Bilge water is seawater which collects in the lower internal parts of the drilling vessel hull. It 

becomes contaminated with oil and grease and with solids such as rust when it collects at low 

points in the bilges. It is usually treated with an oil/water separator to remove oil prior to 

discharge. The general permit prohibits the discharge of any materials that may cause a visible 

sheen of oil. 

Two reported values of bilge water discharges from an Alaskan offshore rig are 195 and 270 

gpd. Therefore, it is estimated that discharges of bilge water under this general permit will be 

less than 270 gpd when discharged. This general permit requires the facilities to report total 

quantity discharged rather than flow rates to provide a more adequate future analysis of bilge 

water quantities discharged. 

2.4.7. Boiler Blowdown 

Boiler blowdown is the discharge of water and minerals drained from boiler drums to minimize 

solids build-up in the boiler. Although boiler blowdown discharges are not planned or likely to 

occur, they may occur intermittently. The general permit prohibits the discharge of free oil in 

this waste stream. 

Under the current permit, discharge quantities varied from 174 to 140,000 gpd based on 

discharge monitoring reports; individual discharge values are provided in Table 2-6. Therefore, 

it is estimated that discharged quantities under this general permit will be highly variable, but 

will not be greater than 140,000 gpd when discharge. This general permit requires the facilities 

to report total quantity discharged rather than flow rates to provide a more adequate future 

analysis of boiler blowdown quantities discharged. 

2.4.8. Test Fluids 

Test fluids are discharges that occur if hydrocarbons located during exploratory drilling are 

tested for formation pressure and content, usually at the completion of drilling. This would 

consist of fluids sent downhole during testing, along with water from the formation. The 
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discharge may consist of formation water, vegetable or mineral oil, natural gas, formation sands, 

any added acids or chemicals, or any combination thereof (USEPA, 1985). Test fluids are 

generally stored and treated with acid to remove oil before being discharged. The addition of 

strong acidic solutions downhole could cause substantial leaching of heavy metals from the 

formation and residual drilling mud. 

The NPDES permit controls these discharges as follows: 

• Oil and grease must have an average monthly concentration less than 29 mg/L and a 

maximum daily average concentration less than 42 mg/L. 

• The pH must be between 6.5 and 8.5 standard units. 

• Free oil is prohibited from being discharged. 

There is currently no data available on the quantity of test fluids discharged in the Arctic; thus, it 

is difficult to predict quantities that will be discharged under this permit. This general permit 

requires the facilities to report total quantity discharged to provide a more adequate future 

analysis of test fluid quantities discharged. 

2.4.9. Excess Cement Slurry 

Excess cement slurry will result from equipment washdown after cementing operations. Excess 

cement slurry is discharged intermittently while drilling, depending on drilling, casing, and 

testing program and problems. 

Under the current permit, discharge quantities varied from 43 to 9,129 gpd based on discharge 

monitoring reports; individual discharge values are provided in Table 2-6. Therefore, it is 

estimated that discharged quantities under this general permit will be highly variable, but will not 

be greater than 10,000 gpd when discharge. This general permit requires the facilities to report 

total quantity discharged rather than flow rates to provide a more adequate future analysis of 

excess cement slurry quantities discharged. 

2.4.10. Mud, Cuttings, Cement at Seafloor 

Mud, Cuttings, Cement at Seafloor are materials discharge at the surface of the ocean floor in the 

early phases of drilling operations, before the well casing is set, and during well abandonment 

and plugging. This discharge is results from the marine riser disconnect and well abandonment 

and plugging. Aside from cement, cement extenders, accelerators, and dispersants are the main 

chemicals added to this discharge. 

There is only one reported value of this discharge from an Alaskan offshore oil and gas facility 

of 94,000 gpd. Therefore, it is estimated that discharges of mud, cuttings, and cement at the 

seafloor under this general permit will be less than 94,000 gpd per well drilled. This general 

permit requires the facilities to report total quantity discharged rather than flow rates to provide a 

more adequate future analysis of bilge water quantities discharged. 
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3.0 TRANSPORT, PERSISTENCE, AND FATE OF MATERIALS 

DISCHARGED 

The primary materials discharged during drilling activities that are of concern to the marine 

environment include water-based drilling fluids (muds), specialty additives, and cuttings; the 

general NPDES permit prohibits the discharge of synthetic-based drilling fluids. Therefore, this 

analysis only discusses the transport, persistence and fate of water-based drilling fluids, specialty 

additives, and cuttings discharged to the marine environment. 

Drilling fluids (muds) contain quantities of coarse material, fine material, dissolved solids, and 

free liquids. This mixture rapidly separates in the receiving water into upper and lower plumes, 

probably from shear forces and local turbulent flow at the discharge pipe (USEPA, 2000a). The 

upper plume contains about five to seven percent, by weight, of the total drilling fluid discharge 

(Ayers et al. as cited in USEPA, 1985). A lower plume contains the majority of the discharged 

materials. 

Upon discharge, much of the discharged drilling muds and cuttings will initially reach the 

seafloor within a few hundred meters from the drilling platform. The thickness of the cuttings 

pile would decrease with distance from the platform. Finer materials, (e.g., barite and clays) 

associated with the cuttings, may extend further out from the platform. The subsequent fate of 

the upper and lower plumes will depend primarily on the physical processes (discussed in 

Section 3.1) that dilute, resuspend and transport particulates or entrain them into the sediments. 

Chemical or biological factors (discussed in Sections 3.2 and 3.3, respectively) significant for 

changes produced in the structure and/or speciation of materials that affect their bioavailability 

and toxicity and could also be important in stabilizing or mobilizing the material on the seafloor 

(e.g., through covalent binding of sediments or bioturbation). 

3.1. PHYSICAL TRANSPORT PROCESSES 

Physical processes include currents, mixing, settling, and diffusion. Factors influencing the 

physical transport and persistence of discharged drilling muds and cuttings include climate and 

meteorology, oceanography, characteristics of the discharge (discussed in Section 2.2), depth of 

discharge, discharge rate (discussed in Section 2.2), and method of disposal. Because ice covers 

the Arctic region during most of the year, three disposal methods are discussed in this section: 

open water disposal, on-ice disposal, and below-ice discharge. Shunting, the extension of the 

discharge outlet well below the sea surface, of drilling mud discharges is also discussed in this 

section. 

Field studies and models of the behavior of drilling fluids and cuttings discharged to the marine 

environment have focused on several aspects of their fate. Among these aspects are: the 

transport of discharged materials in the water column, both for particulate and soluble 

components; deposition on the seafloor; and considerations of benthic short- and long-term fate. 

Field studies are discussed in Section 3.1.5 and predictive models are discussed in Section 3.1.6. 
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In the drilling process, rock fragments (cuttings) are brought to the surface in the drilling fluid 

(muds). These cuttings pose a problem both in the large volume produced and the muds that coat 

the cuttings as they are extracted. Oil-based fluids have the added stigma of having oil 

frequently coating the cuttings. 

Drilling mud disposal generally becomes an issue at the end of the drilling process. However, 

sometimes drilling mud is disposed of during the drilling process when the mud viscosity or 

density needs to be changed to meet the demands of formation pressures. This can create special 

concerns for offshore operations where the disposal of a large volume of mud over a short period 

can create a mud blanket on the seafloor that can have an impact on benthic organisms. Industry 

is limited to using barite stock for the making of drilling mud, which passes 40 CFR 435 

requirements [less than or equal to 1 microgram per kilogram (μg/kg) dry weight maximum 

mercury and 3 milligrams per kilogram (mg/kg) dry weight maximum cadmium]. 

The muds are combined, however, with dissolved and suspended contaminants including 

mercury, cadmium, arsenic and hydrocarbons (typically found in trace amounts). The additives 

listed in Section 2.2, above, may be found in waste mud, and components from the formation, 

such as hydrogen sulfide and natural gas, may also be dissolved in the mud. Rock cuttings from 

the formations overlying the target formation may contribute contaminants to the drilling mud 

such as arsenic or metals. Also rock cuttings create a large volume of waste and for water-based 

fluids the rock cuttings may be discharged to surface waters offshore. Oil-based mud will also 

contain diesel oil that must be disposed of properly, or more typically, conditioned for reuse. Oilbased muds and cuttings cannot be discharged to surface waters. Both oil-based and syntheticbased fluid are conditioned and reused, which reduces waste volume from drilling operations. 

3.1.1. Climate and Meteorology 

The Area of Coverage is located in the Arctic and subarctic climate zones. Important 

meteorological conditions include air temperature, precipitation (rain and snowfall), and wind 

speed and direction. Air temperature controls the ice formation and break-up, precipitation 

determines the quantity and concentration of pollutants discharged in deck drainage discharges, 

and wind speed and direction control coastal oceanographic conditions (ice distribution, current 

speed and direction, vertical and horizontal mixing, and wave action). 

3.1.1.1. Air Temperature 

Mean annual temperature in the Beaufort Sea is about -12° C (10° F). Air temperatures 

generally remain below freezing from September through May; December through March is 

usually the coldest period. 

Along the Chukchi Sea coast north of Point Hope, the average summer temperature range is from 

-2 to 12° C (28 to 54° F), and the average winter temperature ranges from -33 to -6° C (-27 to 

21° F). 
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Mean temperatures within the Norton Basin vary between -15 and -17°C in January and between 

10 and 13°C in July (MMS, 1982). 

3.1.1.2. Precipitation 

Rainfall occurs infrequently in the summer months (July, August and September) averages less 

than 30 millimeters (mm) per month (Hummer in MMS, 2003). Most of the snow falls during 

September and October, when there is still open water on the Beaufort Sea to provide a source of 

moisture. The typical amount of snow received in this region is equivalent to approximately 2.1 

centimeters (cm) [0.8 inches (in)] of precipitation. The average annual precipitation within the 

area of coverage ranges from 13 to 38 cm (5 to 15 in). Annual precipitation averages between 

35.5 and 41.6 cm (14 to 17 in). Most of the rainfall is recorded in the months of July, August 

and September. 

3.1.1.3. Winds 

The Arctic region is a particularly harsh environment, especially during winter (roughly October 

to May) when the sun remains below the horizon for 49 consecutive days. With the ocean to the 

north and level tundra to the south, there are no downslope drainage areas to aid the flow of cold 

air to lower levels, and no natural wind barriers to reduce wind velocities. 

The dominant wind direction in the open-water season is easterly to northeasterly with an 

average wind speed of 5 meters per second (m/s) in Stefansson Sound; wind speeds greater than 

8 m/s fully mix the vertical column of water in Stefansson Sound (MMS, 2003). During winter, 

the area of coverage lies between a semipermanent high-pressure system to the north and a lowpressure system located to the south over the Gulf of Alaska. The northerly high-pressure 

system results in clear to partly cloudy skies much of the time. Strong westerlies are a common 

feature of this region in winter. Cold stable air moving from the north is stacked against the 

Brooks Range and results in a west wind parallel to the mountains. The strength and dominance 

of the westerly winds increase as the Brooks Range is approached. Stations to the east of 

Prudhoe Bay have more frequent westerly winds than stations to the west, such as Barrow. The 

average wind speeds are 4-6 m/s (MMS, 2003). 

Surface winds along the coast between Point Lay and Barrow commonly blow from the east and 

northeast, while winds at Cape Lisburne are predominantly from the east and southeast. Coastal 

wind speeds are typically between 4 to 8 m/s [8 to 16 knots (kn)], with winds exceeding 8 m/s 

(16 kn) occurring less than 4 percent of the time (MMS, 1991). 

Observed win directions over the area are seasonally variable and range from an average summer 

flow of 7 to 10 kn from the south and southwest to a winter flow, which averages 10 to 15 kn 

from the east and southeast. 
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3.1.1.4. Changes in Arctic Climate 

Currently, the causes of the changes in the arctic climate are not well understood; they could be 

cyclical, a trend, or a modal shift. For the purposes of this evaluation, it is assumed that the 

changes are a trend. 

Over the entire Arctic Ocean, the annual trend in surface-air temperature shows a warming of 

about 1.0° C per decade in the eastern Arctic, whereas the western Arctic shows no trend or even 

a slight cooling. During fall, the trends show a cooling of about 1.0° C per decade while spring 

shows a significant warming trend of 2° C per decade. Summer shows no significant trend in 

warming or cooling. [MMS, 2003] 

Additionally, the cold halocline layer, which insulates the sea ice from the relatively warm 

Atlantic waters, appears to have retreated from the Eurasian Basin in recent years. This may be a 

result of atmospheric circulation anomalies causing a diversion of Russian river runoff and has 

important consequences for ice/ocean heat exchange and ice growth rates. [MMS, 2003] 

3.1.2. Oceanography 

Oceanographic considerations include tides, wind, freshwater overflow, ice movement, 

stratification, and current regime. The oceanographic and meteorologic conditions affecting 

dilution and dispersion for the Beaufort and Chukchi seas, and Hope and Norton Basins will be 

briefly summarized below and will include relevant information on conditions with the coastal 

waters of each of these areas. 

3.1.2.1. Bathymetric Features and Water Depths 

The Area of Coverage includes the continental shelf, slope, and rise of the Alaskan Beaufort Sea. 

Depths in the Beaufort Sea Area of Coverage range from 0 (at mean lower low water – MLLW) 

to 1,500 m (4,921 ft). The major bathymetric features include: the barrier islands and shoals; the 

continental shelf, slope, and rise; and abyssal plain. 

Barrier islands serve two main functions: first, they protect the coastlines from severe storm 

damage; and second, they harbor several habitats that are refuges for wildlife. The salt marsh 

ecosystems of the islands and the coast help to purify runoffs from mainland streams and rivers. 

Each of these habitats has distinct animal and plant life that will be discussed in Section 4.0. 

Barrier islands are constantly changing; they are influenced by the following conditions: 

• Waves - deposit and remove sediments from the ocean side of the island 

• Currents - longshore currents that are caused by waves hitting the island at an angle can 

move the sand from one end of the island to another. For example, the offshore currents 
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along the east coast of the United States tend to remove sand from the northern ends of 

barrier islands and deposit it at the southern ends. 

• Tides - move sediments into the salt marshes and eventually fill them in. Thus, the sound 

sides of barrier islands tend to build up as the ocean sides erode. 

• Winds - blow sediments from the beaches to help form dunes and into the marshes, 

which contributes to their build-up. 

• Sea level changes - rising sea levels tend to push barrier islands toward the mainland 

• Storms - storms have the most dramatic effects on barrier islands by creating overwash 

areas and eroding beaches as well as other portions of barrier islands. 

Most of the barrier islands in the Arctic are narrow (less than 250 m) and have low elevations 

(less than 2 m) [MMS, 2003]. 

The continental shelf is a gently sloping submerged plain that is an underwater extension of the 

coastal plain. This is where virtually all of the petroleum and fishery resources are found. The 

continental slopes begin at the shelf break and plunge downward to the great depths of the ocean 

basin proper. Deep submarine canyons are sometimes found cutting across the shelf and slope, 

often extending from the mouths of terrestrial rivers. Many continental slopes end in gently 

sloping, smooth-surfaced features called continental rises. The continental shelf, slope, and rise 

together are called the continental margin. 

Continental shelves vary in width from almost zero up to the 1,500-km-wide [930 miles (mi)] 

Siberian shelf in the Arctic Ocean and average 78 km (48 mi) in width. The edge of the shelf 

occurs at a depth that ranges from 20 to 550 m (66 to 1,800 ft), averaging 130 m (430 ft). The 

shelves consist of vast deposits of sands, muds, and gravels, overlying crystalline rocks or vast 

thicknesses of consolidated sedimentary rocks. Although there is a great variation in shelf 

features, non-glaciated shelves are usually exceptionally flat, with seaward slopes averaging on 

the order of 205 meters per kilometer (m/km) [10 feet per mile (ft/mi)], or less than 1° of slope. 

The edge of the shelf, called the shelf break, is marked by an abrupt increase in slope to an 

average of about 4°. The continental slope in the Beaufort Sea has water depths varying from 60 

(197 ft) to 1,500 m (4,921 ft). The major submarine canyon in the Beaufort Sea is the Barrow 

Canyon just northeast of Barrow, Alaska (MMS, 2003). The continental rises usually have an 

inclination of less than 1/2°. They have been found to consist of thick deposits of sediment, 

presumably deposited as a result of slumping and turbidity currents carrying sediment off the 

shelf and slope. 

Abyssal plains are a broad, relatively flat expanse of sea floor lying 3 to 6 km (2 to 4 mi) below 

sea level. Abyssal plains are found in all the major oceans, and they extend from bordering 

continental rises to mid-oceanic ridges. Abyssal plains are covered in a thick layer of sediment, 

and their flatness is punctuated by rugged low abyssal hills and high sea mounts. 

The coastal waters of the Chukchi Sea are relatively deeper and more steeply sloped than those 

of the Beaufort Sea and are dominated by barrier island protected bays and points and capes that 

extend from the coast and occasionally form protected bays. Within the Chukchi Sea Area of 

Coverage, the continental shelf is broad, has low relief, and is gently incline to the north (MMS 

1991). The entire area of coverage is located on the continental shelf in water depths from 6 to 
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80 m (20 to 262 ft). Approximately 80 percent of the area lies in water depths between 30 and 

60 m (98 and 197 ft). 

The bathymetry of the Bering Sea can be divided into two primary regions: a shelf region (less 

than 150 m deep) to the northeast, and a deeper plain (3,700 to 4,000 m deep) to the southwest. 

Depths in Norton Sound vary from less than 10 m in the southern portion to more than 30 m in a 

trough-like feature which extends east-west in the nearshore region south of Nome. In Norton 

Sound, the marine bottom is relatively featureless and slopes gradually westward to depths of 

about 30 m. The bathymetry of the sound changes with major shifts in substrate in response to 

storm surges and ice gouging. 

3.1.2.2. Circulation 

The circulation in the Beaufort Sea can be divided into two main areas: nearshore (water depths 

less than 40 m; and offshore (water depths greater than 40 m). Offshore waters are primarily 

influenced by the large-scale arctic circulation known as the Beaufort Gyre, which is driven by 

large atmospheric pressure fields. In the Beaufort Gyre, water moves to the west in a clockwise 

motion at a mean rate of 5-10 cm per second. 

There are two distinct periods for nearshore circulation: open water and ice covered. The open 

water circulation depends mostly on the direction (rather than speed) of the wind; the two 

dominant wind directions are northeast and southwest (Morehead et al. as cited in MMS, 2003). 

The nearshore surface currents respond quickly, within 1-3 hours, to changes in the wind 

direction (MMS, 2003). 

In nearshore circulation, easterly winds cause surface currents to flow west and westerly winds 

cause surface currents to flow east. The mean surface current direction year-round is to the west 

and parallels the bathymetry. The tidal action coupled with the easterly nearshore circulation 

results in the gradual removal of warm, brackish water from the nearshore and replaces it with 

colder, more saline water. Alternatively, the tidal action coupled with westerly nearshore 

circulation causes the accumulation of warm, brackish water along the coast. Other controls on 

nearshore circulation include river discharge, ice melt, bathymetry, and the configuration of the 

coastline. 

During ice covered periods, the landfast ice in the nearshore areas protects the water from the 

effects of the winds. Therefore, the circulation pattern is influenced by storms and brine 

drainage (MMS, 2003). 

The Chukchi Sea is fed by Pacific waters and Arctic waters. Pacific waters enter the Chukchi 

Sea through the Bering Strait in the south. Arctic waters enter the Chukchi Sea through Long 

Strait and in episodic up-shelf transfers from the Arctic ocean proper (e.g., via Barrow Canyon). 

The circulation and modification of waters in the Chukchi Sea influences the input to the Arctic 

Ocean from the Pacific. 
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In Norton Sound, the circulation is weakly cyclonic [~ 1.0 centimeters per second (cm/s)]. 

During open water season, the fresh water runoff causes water-column stratification that dictates 

the circulation in Norton Sound. As a result, the upper layer circulation is largely uncoupled 

from that of the lower layer. 

3.1.2.3. Currents 

The direction of the current determines the predominant location of potential impacts, while 

current velocity influences the extent of area affected. Velocity and boundary conditions also 

affect mixing because turbulence increases with current speed and proximity to the seafloor. 

Current velocity and turbulence can vary markedly with location/site characteristics and affect 

the movement and concentration of suspended matter, and entrainment/resuspension/advection 

of sedimented matter. 

The Beaufort Undercurrent is below the surface waters on the continental slope. It moves to the 

east with frequent reversals to the west. The Beaufort Undercurrent is part of a larger cyclonic 

circulation transporting Atlantic water to the Canadian Basin. Long-term mean speeds of the 

undercurrent are about 5-10 cm/s, but daily mean values may be 10-times greater. [MMS, 2003] 

The area lying to the north and west of Point Barrow may be strongly influenced by the Alaskan 

coastal current. This easterly flowing countercurrent enters the Beaufort Sea along Barrow 

Canyon to the west of Point Barrow. The current is a continuation of flow that begins as far 

south as the Bering Sea, and flows through the Bering Strait northward along the coast of the 

Chukchi Sea, where it turns toward the east near Point Barrow. At Point Barrow, the current 

moves offshore and lies at depths between 50 and 200 m (160 to 660 ft). Barrow Canyon mean 

currents range from 14-23 cm/s, with maximum current speeds of approximately 100 cm/s 

(Weingartner et al. as cited in MMS, 2003). 

The currents in the Chukchi Sea are strongly influenced by the bathymetry and wind. Current 

speeds of 20 to 30 cm/s (0.66 to 1.0 cm/s) are characteristic of the eastern Chukchi Sea. Bottom 

temperature gradients and currents are greatest in the vicinity of Icy Cape and Pt. Franklin 

(Weingartner in MMS, 1991). Current velocities of 51 to 87 cm/s have been reported south of 

Icy Cape (MMS, 1990). The influence of Kotzebue Sound on the Chukchi Sea current may be 

significant. Input of the water runoff into Kotzebue Sound may reinforce the Alaska Coastal 

Current (MMS, 1990). 

The Alaska Coastal Current (ACC) is a narrow, fast-moving current flowing northeasterly along 

the Alaska coastline. North of Cape Lisburne, the ACC parallels the 20-meter isobath until it 

reaches the Barrow Sea Valley at Wainwright. It then follows parallel with the valley from 

Wainwright to Point Barrow where it turns and flows southeasterly parallel to the coastline. The 

ACC flow is variable and directional reversals can persist for several weeks due to changes in 

wind direction. During northeasterly flow, clockwise eddies can separate the nearshore 

circulation from the ACC between Cape Lisburne and Icy Cape (MMS, 1990). 
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During open-water periods, the onshore and offshore of nearshore water is driven by the wind. 

Northeasterly winds promote upwelling that brings cooler bottom water into the nearshore area. 

Southwesterly winds establish a warm coastal jet in the nearshore region and remove the cooler 

bottom water. Easterly winds shift the ACC offshore, centering it approximately 20 km from the 

coast. Westerly winds shift the ACC closer to the coast. [MMS, 1990] 

The currents across the mouth of Norton Sound are on the order of 10 cm/s toward the north, 

with noticeable coherence between top and bottom layers. While net flow is to the north, 

reversals can occur, depending on atmospheric pressure difference between the Arctic and 

Bering Seas (MMS, 1982). 

3.1.2.4. Tides 

Tides in nearshore waters are semi-diurnal of low amplitude (range is 6-10 cm) and influenced 

by the wind (MMS, 2003). Offshore tides are nearly nonexistent. Tidal currents within Norton 

Sound are predominantly diurnal, except near the entrance where semi-diurnal components are 

also important. The magnitude of the tidal excursion ranges from negligible near the vicinity of 

the shorefast ice to approximately 13 km in the middle of Norton Sound. The exception is 

intermediate excursions in the vicinity of the Yukon Delta and Nome (Pearson et al. in MMS, 

1982). Tidal height records indicate ranges of 1.6 to 6.8 ft within the Norton Sound Area (MMS, 

1982). 

3.1.2.5. Stratification, Salinity, and Temperature 

Nearshore waters are influenced by fresh water from rivers; a two-layered system is formed with 

fresher water from riverine input overlying more saline oceanic water. The surface layer shows a 

marked decrease in salinity in the vicinity of major rivers, such as the Sagavanirktok, Kuparuk, 

and Colville Rivers. In the winter, the lack of freshwater input into coastal waters results in only 

weak stratification. Freshwater input also causes a marked division between nearshore and 

offshore waters occurring at the 6 m (20 ft) isobath. Alaska Coastal Water temperatures range 

between 5-10° C and has salinities that are generally less than 31.5 parts per thousand (Lewbel 

and Gallaway in MMS, 2003). Offshore waters are colder and more saline than the Alaska 

Coastal Water. Water temperatures are near 0°C and have salinities of 32.2-33 parts per 

thousand (ppt) (Lewbel and Gallaway in MMS, 2003). 

3.1.2.6. Sea Ice 

Sea ice is frozen seawater that floats on the ocean surface, and forms and melts with the polar 

seasons. In the Arctic, some sea ice persists year after year, whereas almost all Southern Ocean 

or Antarctic sea ice is "seasonal ice," meaning it melts away and reforms annually. Sea ice in the 

Arctic appears to play a crucial role in regulating climate because it regulates exchanges of heat, 
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moisture and salinity in the polar oceans. It insulates the relatively warm ocean water from the 

cold polar atmosphere except where cracks, or leads, in the ice allow exchange of heat and water 

vapor from ocean to atmosphere in winter. 

Ice thickness, its spatial extent, and the fraction of open water within the ice pack can vary 

rapidly and profoundly in response to weather and climate. In the Arctic, sea ice typically covers 

about 14 to 16 million square kilometers (km2

) in late winter; the seasonal decrease at summer's 

end is approximately seven to nine million square kilometers. Satellite data provide the best 

means of observing sea ice coverage and variability. A variety of remote sensing instruments 

have been used successfully to map sea ice conditions, but frequent cloud cover in the polar 

regions and the fact that the sun remains below the horizon for continuous periods in winter 

require microwave sensors to map ice cover. 

There are four major zones of sea ice in the Arctic: landfast ice, stamukhi (or shear) ice, packice, and oceanic ice. Each of these zones is discussed below. 

3.1.2.6.1. Landfast-Ice Zone 

Landfast ice, or fast ice, which is attached to the shore, is relatively immobile and extends to 

variable distances off shore; generally 8 to 15-m isobaths, but may extend beyond the 20-m 

isobath. It is usually reformed yearly, although it can contain floes of multiyear pack ice. Much 

of the fast ice melts within the 10-m isobath during the summer, but it is very dependent upon 

the wind direction which controls the ice floes. The two types of landfast ice are bottomfast and 

floating. Bottomfast ice is frozen to the bottom out to a depth of about 2 m. The remaining ice 

is floating. [MMS, 2003] 

3.1.2.6.2. Stamukhi Ice Zone 

Seaward of the landfast-ice zone is the stamukhi, or shear, ice zone. In this zone, large pressure 

ridges and rubble fields occur between the stationary landfast ice and the mobile pack ice when 

winds drive the pack ice into the landfast ice. The ridges can reach depths of 25 m and act as sea 

anchors for the landfast ice. In the Beaufort Sea, the most ridging occurs in waters that are 15-45 

m deep. This zone also contains many leads that are formed between the landfast ice and the 

pack ice when offshore winds carry loose ice away from consolidated ice. [MMS, 2003] 

3.1.2.6.3. Pack-Ice Zone 

Pack ice is located seaward of the stamukhi ice zone and includes first-year ice, multiyear 

undeformed and deformed ice, and ice islands. First year ice forms in fractures, leads and 

polynyas (large areas of open water) and varies in thickness from a few centimeters to more than 

a meter. Leads are formed from southwesterly storms in the Beaufort Sea. Along the western 

Alaskan coast between Point Hope and Point Barrow, there is often a band of open water 

seaward of the landfast-ice zone during winter and spring. The Chukchi open-water system 
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appears to be the result of the general westward motion seen in the Beaufort Gyre and strongly 

influenced by the wind direction. [MMS, 2003] 

Multiyear undeformed ice may reach thicknesses of 3-5 m and has ice floes with diameters 

greater than 500 m that make up 60 percent of the pack-ice zone. Some multiyear undeformed 

ice floes have diameters up to 10 km (MMS, 2003). 

Multiyear deformed ice is identified by ridges that occur shoreward of the 20-meter isobath with 

typical heights of 1-2 meters, but can reach heights over 6 meters. There is increased ridging 

from east to west and generally in the vicinity of shoals and large necks of land (MMS, 2003). 

Ice islands are icebergs that have broken off from an ice shelf with a thickness of 30–50 m and 

from a few thousand square meters to 500 km2

 in area. Ice islands often have an undulated 

surface, which gives them a ribbed appearance from the air (Armstrong et al., 1973). 

Movement of the floating ice is controlled by atmospheric systems and oceanographic 

circulation. During the winter, movement is small and occurs with strong winds that last for 

several days. The long-term direction of ice movement is from east to west in response to the 

Beaufort Gyre; however, there may be short-term variations due to weather systems. 

3.1.2.6.4. Oceanic Ice 

Bering Sea ice is quite mobile and flows predominantly from the Bering Straight towards the 

southern Bering Sea. It consists of a mixture of multiyear floes with annual ice and can be 

completely replaced from three to ten times in any given ice season. As a collective canopy of 

ice, it rarely covers the northern Bering as a solid sheet of ice. Under certain conditions, Bering 

Sea ice can enter Norton Sound. 

3.1.2.6.5. Changes in Arctic Ice 

In recent years, satellite data have indicated an even more dramatic reduction in regional ice 

cover. In September 2002, sea ice in the Arctic reached a record minimum (Serreze et al., 2003), 

4 percent lower than any previous September since 1978, and 14 percent lower than the 1978-

2000 mean. In the past, a low ice year would be followed by a rebound to near-normal 

conditions, but 2002 has been followed by two more low-ice years, both of which almost 

matched the 2002 record. Taking these three years into account, the September ice extent trend 

for 1979-2004 is declining by 7.7 percent per decade (Stroeve et al., 2005). 

Fossil fuel consumption and the resulting increase in global temperatures could explain sea ice 

decline, but the actual cause might be more complicated. The Arctic Oscillation (AO) is a 

seesaw pattern of alternating atmospheric pressure at polar and mid-latitudes. The positive phase 

produces a strong polar vortex, with the mid-latitude jet stream shifted northward. The negative 

phase produces the opposite conditions. From the 1950s to the 1980s, the AO flipped between 

positive and negative phases, but it entered a strong positive pattern between 1989 and 1995. 

This flushed older, thicker ice out of the Arctic, leaving the region with younger, thinner ice that 
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was more prone to summer melting. Thus, sea ice decline may result from natural variability in 

the AO. Growing evidence suggests, however, that greenhouse warming favors the AO's 

positive mode, meaning recent sea ice decline results from a combination of natural variability 

and global warming. 

3.1.2.7. Sediment Transport 

Several factors influence the rate and quantity of sediment transport in the Beaufort Sea, 

including ice gouging, entrainment in sea ice, wave action, currents, and disturbance of 

sediments by the activity of benthic organisms (bioturbation). The bulk of sediment on the 

Alaskan shelf is transported westward on the inner shelf (Barnes and Reimnitz, 1974). 

Catastrophic transport associated with severe storms is an important transport mechanism, 

particularly in the fall when such storms are associated with fresh ice, which enhances the 

erosion and often entraps sediments in the forming ice. Subsequent ice movement and melting in 

the spring can deposit sediment large distances from the point of entrapment. 

Sediment transport and distribution in the Chukchi Sea is controlled by several factors, including 

storms, ice gouging, entrainment in sea ice, wave action, currents, and bioturbation. The bulk of 

sediment on the Alaskan continental shelf is transported northwards in the direction of the 

prevailing current. Sediment transport in response to severe storms is an important means of 

sediment transport within the area of coverage. Storm transport is particularly effective in the 

fall months when storms are associated with fresh ice, which enhances erosion and often entraps 

sediments in new ice. In the spring, the breakup and melting of this sediment-laden ice can 

result in sediment being transported large distances from the point of entrapment. 

3.1.3. Upper Plume Transport Processes 

The materials contained in the upper plume may be subjected to immediate wake-induced 

turbulence, and then are influenced by oceanic turbulent dispersion processes. These materials 

are transported at the speed and direction of prevailing currents. Sinking rates of solids in the 

upper plume will largely depend on four factors: discharged material properties, receiving water 

characteristics, currents and turbulence, and flocculation and agglomeration. 

Physical properties of the discharged materials affect mixing and sedimentation. For suspended 

clay particulates, particle size and both physical and biological flocculation will determine 

settling rate. While oil exhibits little tendency to sink, it has displayed the ability to flocculate 

clay particles and to adsorb to particulates and sink with them to the bottom (Middleditch in 

USEPA, 1985). 

One of the major receiving water characteristics influencing plume behavior is density structure 

and stratification. Density stratification can contribute to the dissipation of dynamic forces in the 

dynamic collapse phase of plume behavior, and represents the point at which passive diffusion 

and settling of the individual particles become the predominant dispersive mechanisms. Density 

stratification may concentrate certain components along the pycnocline. If flocculation produces 
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particles large enough to overcome the barrier, settling will continue. Also, if density 

stratification is weak or the pycnocline is above the discharge point, it may not affect plume 

behavior. 

It has been reported (USEPA, 1985) that upper plumes followed major pycnoclines in the 

receiving water. This type of transport is a potential concern because sensitive life stages of 

planktonic, nektonic, and benthic organisms may collect along the pycnocline. 

Flocculation and agglomeration affect plume behavior by increasing sedimentation rates as 

larger particles are formed. Flocculation is enhanced in salt or brackish waters due to increased 

cohesion of lay particles (Meade in USEPA, 1985). Agglomeration also results in the formation 

of larger particles from a number of smaller ones through the excretion of fecal pellets by filterfeeding organisms. 

The extent to which discharges are dispersed can be estimated using dispersion ratios derived 

from measurements at several drilling operations. These ratios are calculated as: 

Dispersion ratio = suspended solids concentration of discharged fluid . 

 suspended solids concentration in samples 

Most studies of upper plume behavior have measured particulate components and paid less 

attention to the liquid and dissolved materials present. Presumably, these latter components are 

subject to the same physical transport processes, with the exclusion of settling, as particulate 

matter. Studies suggest that suspended solids in the upper plume may undergo a higher 

dispersion rate than dissolved components. 

Because drilling fluids contain both particulate and soluble components, and because particulates 

have an additional mode of dispersion that does not apply to soluble components (i.e., 

gravitational settling, which takes solids out of the water column and transfers them to the 

sediment), several estimates of soluble component dilution also have been made. Generally, it 

appears that dilution of soluble material in the upper plume may proceed at one-half to one-tenth 

that of dispersion particulates in the upper plume. Although these estimates are reasonably 

consistent, this observation must be somewhat tempered, however, because of the difficulties 

involved in assessing interactions between soluble tracers and drilling fluid components, such as 

fine particulates. 

While no specific studies have been conducted in Arctic Alaska, upper plume transport was 

measured in Lower Cook Inlet using a soluble, fluorescent dye (fluorescein) where the currents 

are 41 to 103 cm per second (Houghton et al. in USEPA, 1985). They found that the plume 

never sank below 23 m (75 ft), while water depth at the site was 63 m (207 ft). The Cook Inlet 

data suggested that dilution rates may be comparable to or at a rate approximately half that of 

dispersion (based on generalized estimates of distances to specified levels of dispersion). These 

correlations may be confounded by dye-clay interactions, rendering this comparison more similar 

than would a true “soluble” component. 
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3.1.4. Lower Plume Transport Processes 

The physical transport processes affecting the lower plume differ somewhat from those 

influencing the upper plume. The lower plume appears to have a component, comprised of 

coarser material, which settles rapidly to the bottom regardless of current velocity. This rapid 

settling is most pronounced during high-rate bulk discharges, with their high downward 

momentums, and in shallow water, because these conditions tend to result in the plume reaching 

the bottom. 

The amount of fine solids settling to the bottom from the lower plume depends on collision and 

cohesion of clay particles, which in turn depends on suspended material concentration, salinity, 

and the cohesive quality of the material. Fine particles tend to flocculate more readily than 

larger particles. Physical-chemical flocculation can increase settling rates an order of magnitude 

over rates for individual fine particles. Presently, there are no water column sampling data from 

the lower plume. Its dynamics must be inferred from limited sediment trap data and from 

models of plume behavior. 

Drilling fluid components in a lower plume that reaches the seafloor may be transported as a 

turbulent bottom plume. Solids will continue to settle out while soluble components will be 

diluted with distance. Such plumes have been observed for dredged material disposal, but no 

observations of such plumes for drilling fluids have been attempted. Data on the short-term fate 

of drilling discharges associated with lower plume appears largely to address the initial 

deposition of the material on the seafloor. However, the lack of information on the behavior of 

the lower plume is not critical due to the short duration of drilling activities. 

Biological processes have been shown to increase settling rates for fine particles, which 

presumably could affect drilling discharges. Filter feeding plankton ingest particles ranging 

from 1 to 50 micrometers (μm) in diameter, and excrete them in fecal pellets ranging from 30 to 

3,000 μm in size (USEPA, 1985). Copepods have been cited as playing an important role in 

biologically-induced fine particle agglomeration. 

3.1.5. Seafloor Sedimentation 

Studies have shown the extent of drilling fluid accumulation on the bottom to be inversely 

related to the energy dynamics of the receiving water. Vertical mixing also appears to be 

directly related to energy dynamics. Low energy environments, however, are not subject to 

currents removing deposited material from the bottom or mixing it into sediments. Vertical 

incorporation of plume components into sediments is caused by physical resuspension processes 

and by biological reworking of sediments. The relative contribution of these processes to mixing 

has not been quantified. 

Houghton et al. (1981) produced an idealized pattern for sedimentation around an offshore 

platform located in a tidal regime (Figure 3-1); zero net current was assumed. The area of 

impact may have been overestimated from the true field case because no initial downward 
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motion was assumed, which provides for a longer settling time and greater plume dispersion. 

The result was an elliptical pattern, with the coarse fraction (10 to 2 mm) deposited within 125 to 

175 m (410 to 574 ft) of the discharge point, the intermediate fraction (2 mm to 250 μm) 

deposited at 1,000 to 1,400 m (3,280 to 4,592 ft), and the medium fraction 

(250 to 74 μm) deposited beyond that distance. This is the greatest areal extent of bottom 

sedimentation for continuous discharges under the assumed conditions. Discontinuous 

discharges will be transported by currents at the time of release and will form a starburst pattern 

over time. 

Currie and Isaacs (2004) examined changes to benthic infauna caused by exploratory gas drilling 

operations in the Minerva field located in Port Campbell, Australia. They found the abundances 

of two common species (Apseudes sp. 1 and Prionospio coorilla) decreased significantly at the 

well-head site immediately after drilling. The size of these reductions in abundance ranged 

between 71 and 88 percent, and persisted for less than 4 months after drilling (Currie and Isaacs, 

2004). Additionally, modified communities persisted at the well-head for more than 11 months 

following exploratory drilling. Changes in the abundance of species aggregated by phylum 

varied, but significant declines in the most abundant phyla (crustaceans and polychaetes) of 45 to 

73 percent were observed at all sites within a 100 m radius of the well-head following drilling 

(Currie and Isaacs, 2004). In most cases these changes became undetectable four months after 

drilling following species recruitments. 

3.1.6. Studies in Arctic Alaska 

The transport, persistence and fate of materials discharged into the marine environment from 

exploratory drilling operations have been previously evaluated for several northern Alaska 

offshore areas of coverage. The general conclusions reached in these studies regarding the 

transport, dispersion, and persistence of drilling discharges is summarized below: 

• The drilling mud discharge separates into an upper and lower plume. Physical 

descriptions of effluent dynamics and particle transport differ substantially for the two 

plumes. 

• Drill cuttings (parent material from the drill hole) are generally coarse materials that are 

deposited rapidly following discharge and settle within the 100-m radius mixing zone. 

• Discharged drilling materials typically settle in the immediate vicinity of the discharge 

area. However, deposition patterns are extremely variable and are strongly influenced by 

several factors, including the type and quantity of mud discharged, hydrographic 

conditions at the time of discharge, and height above the seafloor at which discharges a 

made. 

• Although metals were enriched in the sediment, enrichment factors were generally low to 

moderate, seldom exceeding a factor of 10. The spatial extent of this enrichment also 

was limited. These considerations suggest that exploratory activities will not result in 

environmentally significant levels of trace metal contamination. However, other factors, 

such as the intensity of exploratory activities, normal sediment loading, and proximity 

either to commercial shell fisheries or to subsistence populations, could alter this 

conclusion. 
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• Analyses of sediment barium and trace metal concentrations have been used to examine 

nearfield fate of drilling fluids on the seafloor (e.g., the rate of dispersion of sedimented 

material). If high concentrations of barium are persistently found near a well site, this 

finding suggests it is in a lower energy area, which favors deposition. If elevated levels 

cannot be found, even soon after drilling, then this finding suggests a higher energy 

environment, where resuspension and sediment transport were promoted. 

• Data from exploratory drilling operations have been used to examine deposition of metals 

resulting from drilling operations. These indicate that several metals are deposited, in a 

distance-dependent manner, around platforms, including cadmium, chromium, lead, 

mercury, nickel, vanadium, and zinc. 

• At present, the area-wide large-scale distribution of drilling discharges is difficult to 

predict. However, it can be surmised that drilling discharges associated with short-term 

exploration operations will have little effect on the environment due to deposition of 

drilling-related materials on the seafloor. 

3.1.6.1. Trace Metal and Physical Benthic Alterations 

A study has investigated the environmental distribution of metals from drilling fluids discharged 

into the Beaufort Sea, near the Mackenzie River Delta (Crippen et al., 1980). The primary 

objective of the program was to investigate the environmental significance of metals in drilling 

fluids discharged to the marine environment. The study site was an artificial island constructed 

from local borrow material in the Beaufort Sea near the Mackenzie River delta. The average 

depth of the study area was approximately seven meters. A total of 47 stations were sampled for 

arsenic, cadmium, chromium, lead, mercury, and zinc in the sediments and infaunal tissues. 

The concentration of arsenic, cadmium, chromium, lead, and zinc in surface sediments exceeded 

background levels at one or more stations in the vicinity of the discharge. Subsurface 

concentrations of most metals, excluding chromium, were substantially higher than surface 

sediment sample 45 m SW of this discharge location. This sample was thought to be a pocket of 

drilling fluid from operations prior to the use of chrome lignosulfonate. Mercury contamination 

of sediments was obvious within 100 m of the point of discharge, and mercury levels were 

somewhat elevated above mean background levels [0.07 micrograms per gram (μg/g)] at several 

other stations. The highest mean value recorded was 6.4 μg/g located less than 45 meters from 

the shoreline of the island, just north of the discharge. 

Another study was conducted to monitor the environment fate associated with above ice disposal 

of drilling fluids and cuttings in the Beaufort Sea (Sohio Alaska Petroleum Company, 1980). 

Three wells were sampled, Sagavanirktok Delta Wells #7 and #8 (Sag 7 and Sag 8), and 

Challenge Island Well #1 (Challenge 1). Three sites (A, B, and C) were sampled at Challenge 1. 

F-test analyses indicated that there were no significant differences (P < 0.05) among any preversus post-discharge tests at disposal sites. For post-discharge tests of disposal sites versus 

reference sites, a few significant differences were found. Median grain size decreased at Sag 8 

and Challenge 1 (Site C) for the >0.25 mm (percentage coarser) fraction and at Sag 8 for the 
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>0.150 mm fraction. Increased median grain size occurred for the >0.250 mm fraction at 

Challenge 1 (Sites A and B) and for the >0.150 mm fraction (Site B). 

Trace metal analysis were conducted on samples of drilling fluids that were disposed. 

Comparison of pre- and post-discharge bottom sediment samples from Sag 7 indicated 

significant decreases in levels of barium, cadmium, and mercury that were judged unrelated to 

drilling fluids. Analyses of samples from Sag 8 indicated only that barium levels decreased 

significantly. 

Analyses of Challenge 1 samples indicated significant increases in levels of cadmium, 

chromium, lead, and zinc at Sites A and B, and in copper, lead, and zinc at Site C. Increases of 

chromium and zinc were considered related to drilling fluids disposal. Cadmium data were not 

considered to be explained by effluent discharges because cadmium levels in the effluents and 

pre-discharge sediments were similar. Elevations in lead were not judged to be drilling fluidrelated because of spatial patterns, other sediment characteristics, and because Site C did not 

melt in place. 

However, elevations of cadmium and lead levels could be effluent-related. Although cadmium 

levels in early drilling fluid samples (0.2 mg/kg) were similar to pre-discharge sediment levels 

(0.19-0.35 mg/kg), an enrichment of cadmium in drilling fluid effluents occurred at all disposal 

sites over time, to 0.8-1.1 mg/kg. Also, for cadmium, chromium, lead, and zinc sediment levels 

were inversely related to distance from disposal sites (A and B) for 0-60 m, 60-85 m, and 250 m 

data sets. 

Furthermore, for cadmium, lead, and zinc at Sag 7 and chromium, copper, lead, and zinc at Sag 

8, a consistent spatial pattern of enrichment at the nearfield stations (approximately 85-200 m) 

occurred relative to pre-discharge levels and either within-site or far-field (315-585 m) stations. 

These enrichments were not statistically significant. However, trace metal levels had 95 percent 

confidence levels that averaged about 65 percent of the mean. This large variability substantially 

reduces the ability to statistically resolve differences among data sets. 

Nonetheless, near-field enrichments were consistent. For both lead and zinc, enrichment was 

1.3-fold at Sag 7 and 1.2-fold at Sag 8, versus 2.3- to 2.6-fold for lead and 1.4-fold for zinc at 

Challenge 1. Chromium levels at Sag 7 increased 2-fold versus 1.4-fold at Challenge 1. 

A study has assessed the impacts of above-ice drilling effluent disposal techniques in the 

Beaufort Sea (Sohio Alaska Petroleum Company, 1981), between the Midway Islands and 

Prudhoe Bay. A simulated, above-ice disposal test was conducted. 

Grain size analyses of settling pan sediment indicated that a rapid decrease in deposition rates 

occurred for most particle sizes. At the center of the discharge hole, deposition was 729 

milligrams per square centimeters (mg/cm2

) for all grain size fractions. At 1.5 m and 3.0 m, 

average deposition was 313 mg/cm2 and 168 mg/cm2, respectively. It was estimated that the 

average deposition of all particle sizes was about 200 mg/cm2

 over the test site. The average 

deposition rate for particles less than 45 microns, measure 3 m from the discharge point, was in 

the same general range of deposition rates measured at two below-ice disposal sites (166 mg/cm2
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versus 66-268 mg/cm2, respectively). Bottom sediment trace metal levels indicated the presence 

of drilling effluents three days after the discharge, but not tree months post-discharge. 

Trace metal analyses of drilling fluid samples and sediments were conducted both within and 

near the disposal sites. At one site there were no notable differences as a result of drilling 

activities. At the second site, however, three metals showed possible enrichment: cobalt, 

copper, and iron. 

These sediment metal studies, when considered as a group (Table 3-1), suggest the enrichment of 

certain metals in surficial sediments may occur as a result of drilling activities. While 

confounding factors occur in most of these studies (i.e., seasonal variability and other natural and 

anthropogenic sources of these metals) a distance-dependent decrease in metal levels frequently 

is observed. However, although drilling activities are implicated as a source of metal 

enrichment, discharged drilling fluids and cuttings probably are not the only drilling-related 

source. 

Barium and chromium are the only two metals that appear to be elevated around rigs or 

platforms and are clearly associated with drilling fluids. A study in the Canadian Arctic found 

that mercury would be the best trace metal tracer of discharged fluids. Examination of mercury 

levels in fluids and sediments for domestic operations is notably under-represented in the studies 

that have been reviewed. The degree of similarity between Canadian and domestic operations 

has not been evaluated. However, the findings of the Netserk study and lack of information on 

domestic operations indicate that the relationship between drilling fluid discharges and sediment 

mercury levels should be further clarified. 

Metals that appear to be elevated as a result of drilling activities, and not solely related to drilling 

fluids, include cadmium, mercury, nickel, lead, vanadium, and zinc. Cadmium, lead, and zinc 

may be associated with drilling fluids as contaminants that occur from the use of pipe dope or 

pipe thread compounds. Mercury, nickel, and zinc may originate from sacrificial anodes. 

Cadmium, lead, and vanadium may also originate from the release of fossil fuel in drilling 

operations. This release can result from burning, incidental discharges or spills from the rig or 

supply boat traffic, or use as a lubricant in drilling fluids. Vanadium also may derive from 

wearing of drill bits. 

Although these metals were enriched in the sediment, enrichment factors were generally low to 

moderate, seldom exceeding a factor of 10. The spatial extent of this enrichment also was 

limited. Either of two cases occurred: enrichment was generally distributed but undetectable 

beyond 300-500 m or enrichment was directionally-based by bottom current flows and extended 

further (to about 1,800 m) but within a smaller angular component. 

These considerations suggest that exploratory activities will not result in environmentally 

significant levels of trace metal contamination. However, other factors, such as the intensity of 

exploratory activities, normal sediment loading, and proximity either to commercial shell 

fisheries or to subsistence populations, could alter this conclusion. 
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3.1.6.2. Drilling Fluids Toxicity 

Drilling fluids (muds) are complex mixtures and there appears to be no single explanation for 

toxicity. Some of the apparent (actual) toxicity may be due to physical effects, such as particle 

size coagulations, abrasions, etc. These are, however, a form of toxicity, producing and 

contributing, in part or in combination with chemical toxicity, to the end points (death) in acute 

toxicity tests. 

Oxygen demand appears strongly correlated with toxicity in laboratory toxicity tests. Spearman 

Rank correlations of 96-hour LC50 data and biochemical oxygen demand (BOD)/ultimate oxygen 

demand (UOD) data showed a remarkably strong correlation, especially with 5-day biochemical 

oxygen demand (BOD5) data derived with artificial seawater and activated seed. These data 

showed a correlation of 0.97 with toxicity. All BOD/UOD values showed correlations of 0.87 to 

0.97 BOD and 0.91 to 0.95 UOD, but total organic carbon (TOC)/chemical oxygen demand 

(COD) values gave correlations of 0.64 to 0.67. Given the absence of oxygen demand data, no 

such correlation could be developed for nongeneric muds. Another indicator of the large 

inherent oxygen demand of drilling muds is that dissolved oxygen levels in test environments 

dropped below normal, notwithstanding the continuous aeration of test media that followed preaeration of the test material. This was especially noted during the first day of testing, during 

which dissolved oxygen levels were depressed concentration dependently by the test muds. 

A variety of Alaskan marine organisms have been exposed to drilling mud in laboratory or field 

experiments. Most of these studies have addressed short-term acute effects in a relative or 

“screening” sense, with little effort directed at separating chemical from physical causes. [In 

aquatic toxicity tests, a response measuring 50 percent lethality observed in 96 hours or less is 

typically considered acute (LC50)]. A few studies have looked at chronic sublethal effects and 

bioaccumulation of heavy metals from drilling mud. Chronic refers to a stimulus that lingers or 

continues for a relatively long period of time, often one-tenth of the life span of an organism or 

more (USEPA, 1991). Chronic tests assess the effect on survivability, growth, maturation or 

reproduction and the results are typically reported as median effective concentrations [EC5Os 

(concentrations at which a designated effect is displayed by 50 percent of the test organisms)]. 

Because drilling discharges are episodic and typically only a few hours in duration, organisms 

that live in the water column are not likely to have long-term exposures to drilling muds; risks to 

these organisms are best assessed using acute toxicity data. Benthic organisms, particularly 

sessile species, are likely to be exposed for longer time periods; risks to these organisms are best 

assessed with chronic toxicity data. 

Drilling mud toxicity tests have been performed using whole muds or various component 

fractions, such as the suspended particulate phase or mud aqueous fraction. The variability and 

complexity in the composition of muds is reflected in the results and interpretation of toxicity 

tests. Test results of sample splits of the same mud performed at two different laboratories have 

differed by an order of magnitude. In such cases, laboratory procedure or sample handling is a 

significant factor. Different batches of the same generic mud have shown significantly different 

toxicities. In this case, different proportions of major constituents (as allowed by mud type 

definition) may be a factor. EPA has attempted to improve consistency in toxicity test results by 
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requiring standard procedures for sample handling and testing that has resulted in consistent test 

results. The current effluent guidelines require toxicity testing for the suspended particulate 

phase. The extrapolation of single species toxicity tests to overall effects in the ecosystem still 

has a large, inherent uncertainty. 

3.1.6.2.1. Acute Lethal and Sublethal Effects 

The effects of drilling muds on biological organisms are most commonly assessed by conducting 

acute laboratory toxicity tests. Unfortunately, in many cases, comparison of toxicity test results 

obtained in different studies are difficult because different drilling muds were used, the animals 

were exposed to different portions of drilling mud (liquid, suspended particulates, or solids) that 

may have been prepared in a different manner, or experimental procedures differed between 

investigators. Nevertheless, results obtained in the majority of studies to date have generally 

indicated low toxicity. 

In a summary of over 415 toxicity tests of 68 muds using 70 species, 1-2 percent exhibited LC50s 

ranging from 100 to 999 ppm, 6 percent exhibited LC50s ranging from 1,000 to 9,999 ppm, 46 

percent exhibited LC50s ranging from 10,000 to 99,999 ppm, and 44 percent exhibited LC50s 

greater than 100,000 ppm (USEPA, 1985). Table 3-2 provides a summary of these toxicity tests. 

Two to three percent of the data were not usable. A significant difference was noted between the 

toxicity of generic muds, which appear to have acute, lethal toxicity characteristics similar to the 

distribution of the larger data set described above, and a series of 11 nongeneric muds provided 

to EPA by the Petroleum Equipment Supplies Association. These latter muds, as a group, appear 

to be substantially more toxic than would be anticipated from the toxicity distribution of either 

the generic muds or the larger data set. Whole muds appear to be more toxic than aqueous or 

particulate fractions. The suspended particulate phase appears to be more toxic than the other 

individual phases. 

Petrazzuolo (1981) has ranked organisms according to their sensitivity to drilling fluids in tests 

and found the following order of decreasing sensitivity: copepods and other plankton, shrimp, 

lobsters, mysids and finfish, bivalves, crabs, amphipods, echinoderms, gastropods, and 

polychaetes and isopods. Larval organisms are more sensitive than adult stages (maximally 20-

fold); animals are more susceptible during molting. 

Some Alaskan organisms apparently show high tolerance to acute exposure to drilling mud 

(Tornberg et al. in USEPA, 1985). Sublethal effects observed following acute exposure have 

included alteration of respiration and filtration rates, enzyme activities, and behavior. There are 

several Alaskan taxa that have not been exposed to drilling mud but may be relatively sensitive. 

The temperate copepod, Acartia tonsa, has exhibited one of the lowest LC5Os (100 ppm) of any 

organism in a drilling mud. Alaskan copepods have not been tested, but there is no reason to 

believe their tolerances would fall outside variability in tolerances of other marine copepods. 

In general, planktonic and larval forms appear to be the most sensitive of the Alaskan organisms 

that have been exposed to drilling mud in acute lethal bioassays; however, not all planktonic 

organisms are sensitive to short-term exposure to drilling muds. Carls and Rice (1981) found 
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several drilling muds to have low toxicity to the larvae of six Alaskan species of shrimp and 

crab. The 96-hour LC5Os for the suspended particulates phase of a drilling mud seawater 

mixture ranged from 500 to 9,400 ppm. Toxicity was far less when the particulates were 

removed: the 96-hour LC5Os ranged from 5,800 to 119,000 ppm. 

Houghton et al. (1981) conducted a study on several species of crusacea, including a shrimp 

(Pandalus hypsinotus), a mysid (Neomysis integer), an amphipod (Eogammarus confervicolus), 

and an isopod (Gnorimosphaeroma oregonensis), and pink salmon fry (Onchorhyncus 

gorbuscha). These species were exposed to used high-density lignosulfonate drilling fluid from 

lower Cook Inlet, Alaska. Pink salmon fry were the most sensitive with a 96-hour LC50 of 3,000 

ppm for SSP. The lowest crustacean concentration was ten time higher. 

Seven arctic polymer drilling fluids were used for toxicity testing of salmon (Houghton et al. in 

USEPA, 1985). Five of the seven fluids displayed a 96-hour LC50 of less than 40,000 ppm for 

the SSP fraction; the most toxic fluid had a 96-hour LC50 of 15,000 ppm, and the least toxic fluid 

a 96-hour LC50 of 190,000 ppm. Clam worms (polychaetes), soft-shelled clams, purple shore 

crabs, and sand fleas had approximately the same sensitivity to the fluids as did the salmon. 

These invertebrate 96-hour LC50’s ranged from 10,000 to more than 560,000 ppm. 

Unlike the water-based drilling fluids (WBFs), the synthetic-based drilling fluids (SBFs) are 

water insoluble and do not disperse in the water column as do WBFs, but rather sink to the 

bottom with little dispersion (USEPA, 2000a). Since 1984, the USEPA has used the suspended 

particulate phase (SPP) toxicity test, an aqueous-phase toxicity test, to evaluate the toxicity of 

drilling fluids, including SBFs. Using the SPP toxicity test, SBFs have routinely been found to 

have low toxicity; however, an interlaboratory variability study indicated that SPP toxicity 

results are highly variable when applied to SBFs (USEPA, 2000a). Table 3-3 summarizes 

toxicity test results conducted with water-column and benthic organisms for several different 

SBFs. In general, benthic test organisms appear to be more sensitive to the SBFs than watercolumn organisms. Further evaluation of these studies determined the ranking for SBF toxicity 

from least toxic to most toxic is: esters-internal olefins-linear alpha olefins-polyalphaolefinsparaffins (USEPA, 2000a). 

The current NPDES permit has incorporated a standard acute toxicity test for drilling fluids prior 

to discharge. The acute toxicity test must result in an LC50 value higher than 30,000 ppm for 

discharge of the cuttings to be permitted. The permit requires the use of the species mysid 

Mysidopsis bahia for the toxicity test. Drilling mud toxicity data compiled by USEPA, Region 

10 from Alaskan exploratory and production wells indicate that the muds used in all current and 

recent operations are acutely toxic only to a slight degree to Mysidopsis bahia. LC5Os for the 91 

valid toxicity test data points ranged from 2,704 to 1,000,000 ppm SPP with a mean of 540,800 

ppm. Only 7 of the 91 tests had LC5Os less than the 30,000 ppm limit. Some of the records in 

this database were not included in the above statistics due to pH or other protocol breaches, 

incomplete reports, etc. 
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3.1.6.2.2. Chronic Effects 

Few studies have evaluated impacts on Alaskan species following chronic exposure to drilling 

muds; the species that have been tested are all invertebrates. The few chronic data are consistent, 

however, and indicate that chronic lethal toxicity is not likely to be more than some 20-fold 

greater than acute lethal toxicity; chronic sublethal toxicity appears to range from three-fold to 

75-fold greater than acute lethal toxicity, which is within the same range as chronic lethal effects. 

However, the chronic sublethal data are much more difficult to interpret, physiologically and 

ecologically. Sample sizes routinely are very small. Most importantly, observations that 

sublethal effects occur “close” to lethal effect levels miss the point; for most studies changes 

were also noted at the lowest level tested. Thus, estimating No-Observable-Effect-Levels 

(NOELs) are not possible for much of the reported data. 

Laboratory studies on recruitment and development of benthic communities suggest that drilling 

mud and barite can affect recruitment and alter benthic communities or depress abundances. 

These data are corroborated by results from artificial substrate experiments conducted in the 

Beaufort Sea; these showed significantly different colonization rates at drilling fluid test plots 

and control plots, especially for amphipods and copepods. 

The lowest reported concentration of drilling mud producing a significant sublethal chronic 

effect was 50 mg/L for 30 days of continuous exposure with bay mussels, and there was no 

attempt to separate chemical from physical effects (USEPA, 1985). 

A laboratory study examined the chronic toxicity of cuttings from Beaufort Sea wells on the sand 

dollar (Echinarachnius parma) (Osborne & Leeder, 1989). Exposure to mixtures as low as 10 

percent cuttings/90 percent sand were found to affect the survival of the benthic organisms, with 

100 percent mortality occurring within 23 days in some test cases. 

Other altered behavioral patterns in organisms have been noted after chronic exposures to 

drilling mud. USEPA (1985) discusses a study where dock shrimp and Dungeness crab larvae 

were exposed to 4,000 to 200,000 ppm barite and 4,000 to 100,000 ppm bentonite. The EC40 

concentration inhibiting the swimming ability of half of the crab larvae ranged from 77,600 to 

85,600 ppm bentonite, and was 71,400 ppm for barite. EC50’s for shrimp larvae ranged from 

13,800 to 34,600 ppm bentonite, and 5,400 to 50,400 ppm barite. 

3.1.6.2.3. Toxicity of Mineral and Diesel Oil 

In the past, the oil industry has added diesel oil to drilling fluid systems to free stuck drilling pipe 

and for other specialized applications. Diesel oil is highly toxic to aquatic life, and much of the 

toxicity (96-hour LC50) of drilling muds has been attributed to its presence. Studies have found 

high correlations of toxicity with added diesel and mineral oil to whole mud (diesel oil r=0.88; 

mineral oil r-0.97). Toxicity did not correlate quite as well with the oil levels determined in a 

variety of mud samples (r=0.81) (USEPA, 1985). The available data indicate that this may be 
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partially due to various types of sequestrations within the drilling fluid matrix as well as the 

variable presence of toxic constituents in drilling fluids other than diesel or mineral oil. 

Because of the toxicity of diesel oil, USEPA has prohibited its discharge in muds and cuttings. 

Instead, USEPA allows the use of mineral oils to free stuck pipes and the discharge of residual 

amounts of mineral oil pills, provided that the pill and a buffer of drilling fluid on either side of 

the pill are removed and not discharged. The residual mineral oil concentration in the discharged 

mud should not exceed 2 percent (v/v) and must comply with all previous permit conditions (53

FR 37857, September 28, 1988). 

According to the API Hydrocarbon Usage Survey and the OOC Spotting Fluid Survey (USEPA, 

1993a), diesel oil was still being used for lubricity agents and spotting fluids as of 1986. With 

the advent of Best Practicable Control Technology Currently Available (BPT) effluent limitation 

guidelines, however, current diesel oil usage for these purposes is assumed to be zero (USEPA, 

1993a). 

Mineral oils differ from diesel oils in that they contain a lower concentration of aromatic 

hydrocarbons (15-20 percent vs. 20-61 percent for diesel oil) (USEPA, 1993a). In addition, 

saturated aliphatics (paraffinics) generally represent a larger percentage of mineral oils compared 

to diesel oil. Aromatic hydrocarbons are generally more toxic and resist biodegradation to a 

greater degree than do paraffinics (Petrazzuolo, 1983). Research studies indicate that some 

mineral oils are much less acutely toxic (5 to 30 times less) to certain marine organisms than 

diesel oil (USEPA, 1985). 

Despite the reduced toxicity of some mineral oils as compared to diesel oils, mineral oils do 

contribute potentially toxic organic pollutants (Table 2-3) to drilling muds to which they are 

added. The potential for drilling muds containing mineral oils to violate Federal water quality 

criteria is discussed in Section 9.0. 

Neither mineral nor diesel oils possess constituents that can be biomagnified (see definition in 

Section 3.3.2). However, both compounds contain PAHs, which are lipid soluble and lipophillic 

and some of these compounds can bioaccumulated (see definition in 3.3.1) in organisms that 

consume prey contaminated with hydrocarbons. As stated earlier, mineral oils contain a lower 

concentration of aromatic hydrocarbons (15-20 percent vs. 20-61 percent for diesel). Due to the 

fact that the total amount of mineral oil released in the drilling cuttings is, effects in aquatic 

organisms due to exposure to PAH residues is not expected to be significant. 

3.1.6.3. Open-Water Discharges 

Only one Arctic discharge study has considered discharges during the open water period. 

Northern Technical Services (NORTEC, 1983) conducted a drilling effluent disposal study at 

Tern Island located in the Beaufort Sea. Case 1 conditions included a mud discharge rate of 13.3 

cubic meters per hour (m3

/h) [84 barrels per hour (bbl/h)], a predilution of 30:1 with seawater, 

and an average current velocity of 12 cm/s [0.39 feet per second (ft/s)] at 3.4 m (11.2 ft) above 
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the seafloor. Case 2 conditions included a mud discharge rate of 5.4 m3/h (34 bbl/h), predilution 

of 75:1 with seawater, and an average current of 11 cm/s (0.36 ft/s). The minimum dilution (due 

to ambient waters only) measured for test plot 1 was 167:1 at 100 m (330 ft) and 320:1 at 160 m 

(530 ft) from the discharge for test plot 2. During this study, effluents remained within 0.5 m 

(1.6 ft) of the seafloor in the nearfield [within 10 m (33 ft) of the discharge point], and most 

solids were deposited within 240 m (787 ft) of the discharge point in shallow water, 

approximately 5.5 m (18 ft) in depth. 

3.1.6.4. Below-Ice Discharges 

Dilution of drilling fluids in the water column beneath ice has been examined in the Beaufort 

Sea. Results suggested that nearfield dilution (100- to 1,000-fold) was 1-2 orders of magnitude 

less than in open water situations. However, at dilution ratios of 104

 to 106, the dilution under 

ice appeared to approach that in open water. Sampling problems encountered in this study may 

have resulted in an overestimation of far-field dispersion. Therefore, these data must be 

interpreted very cautiously. 

Northern Technical Services (NORTEC, 1981) conducted two shallow water under-ice effluent 

disposal studies in 8.4 m (27.6 ft) and 5.5 m (18.0 ft) off Reindeer Island in the Beaufort Sea. 

The minimum dilution was 112:1 at a distance of 61 m (200 ft) from the point of discharge. This 

value is about an order of magnitude lower than solids dilutions typical of open-water disposal 

model results (Table 3-5). 

NORTEC (1984) conducted a study to determine the areal extent and distribution of drilling 

solids discharged from Seal Island, an artificial gravel island located at a depth of 12 m (39 ft) in 

the Beaufort Sea. The area of cuttings deposited was limited mainly to the submerged portion of 

the island. Cuttings 8 to 15 cm (3 to 6 in) thick extended less than 61 m (200 ft) beyond the toe 

of the island. 

NORTEC (1985) identified the distribution of drilling muds discharged under the ice from 

Mukluk Island, an artificial gravel island located approximately 45 km (24 nmi) offshore in a 

depth of 15 m (49 ft). Analysis of trace metal concentrations in bottom sediments near the 

Mukluk Island discharge site indicated that drilling muds were deposited up to 155 m (509 ft) 

from the toe of the island. Although metals levels were elevated from the ambient levels for the 

area, they were still within the range of values found elsewhere in the Beaufort Sea. 

3.1.6.5. Above-Ice Discharges 

Field studies (Sohio Alaska Petroleum Company, 1980, 1981) have found that the maximum 

mud concentration entering the marine environment from above-ice disposal sites is much less 

than the concentration introduced by below-ice discharge. Dilution of muds discharged above 

ice should be similar to or greater than that occurring during discharge to open waters, as the 

solids are released slowly during ice melting and breakup allowing greater dispersion. 
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3.1.7. Predictive Modeling of Drilling Mud Transport, Deposition, and Dilution 

A model has been developed by the Offshore Operators Committee (OOC) for predicting the 

behavior of solid and soluble components of the lower plume; the OOC model was first made 

available to OOC member companies and federal and state agencies concerned with offshore 

drilling discharge regulation in 1983. The OOC model considers the drilling discharge plume to 

be divided into an upper plume, which contains fine-grained solids, and a lower plume, which 

contains the majority of solids. The dilution of the drilling effluent simulated by considering 

three phases of plume behavior: convective descent, dynamic collapse, and a later passive 

diffusion phase. A Gaussian formulation is used to sum the three component phases and to track 

the distribution of solids to the bottom. The model predicts concentrations of solids and soluble 

components in the water column and the initial deposition of solids on the seafloor. 

The OOC model results do not include cuttings because they are expected to be of coarser grain 

size than muds and will, therefore, settle rapidly to the seafloor. However, the total discharge of 

cuttings is generally about 1.3 times greater than (as dry weight) the total discharge of drilling 

muds for these operations. Thus, the nearfield estimates (within 100 m of the point of discharge) 

of bottom accumulations of drilling mud should be considered underestimates due to the 

exclusion of cuttings discharge from the OOC model. 

Comparison of mode1 results with field observations indicates that the model is capable of 

predicting many important aspects of drilling mud discharge plume behavior. For example, a 

field verification study was conducted offshore of Huntington Beach, California, in waters with 

an average depth of approximately 18 m using a modified version of the OOC model (O’Reilly 

et al., 1989). The model predicted water column solids concentrations were within the range of 

concentrations measured at 75 percent of the sampling locations. In the lower water layer where 

the majority of the solids formed the lower plume, the model predicted the solids concentrations 

at 86 percent of the lower water layer sampling locations. However, comparison of the model 

predictions of bottom solids accumulation with field sediment trap data was less satisfactory, 

possibly due to errors associated with the field measurement technique that was used. 

The OOC model makes several simplifying assumptions that may vary from actual conditions at 

any given site (e.g., a single discharge of limited duration and unidirectional currents). 

Therefore, the model predictions discussed below provide a generalized picture of expected 

dilution and deposition; but the model is not expected to predict exact conditions at any one well 

location. The model version employed for this ODCE is Version 1.0 supplied by Brandsma 

Engineering and is identical to that used in the previous Arctic ODCE (USEPA, 1995). 

The OOC model was used to examine discharge scenarios that were 1) likely to occur in the 

areas of coverage, and 2) representative of the maximum allowable discharges. Therefore, 

discharges were only evaluated for the Beaufort and Chukchi Seas since it was determined that 

discharges in the Hope and Norton Basins were not likely to occur (see Section 2.2.1). 

Discharge scenarios were determined by examining relevant information sources describing 

exploratory oil and gas drilling practices. Maximum allowable discharges are those specified in 

the NPDES general permit for the Arctic, which are based on previous OOC model runs for 

earlier ODCEs in this area. Model parameters held constant for all test cases are given in Table 
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3-4. The NPDES permit states that the total drilling muds and drill cuttings discharge rate shall 

not exceed the following rates where depth is measured as meters from MLLW: 

• 1,000 bbl/h in water depths exceeding 40 m; 

• 750 bbl/h in water depths greater than 20 m but not exceeding 40 m; 

• 500 bbl/h in water depths greater than 5 m but not exceeding 20 m; and 

• no discharge in water depths less than 5 m. 

In addition to the depth-related discharge requirements, the NPDES general permit also specifies 

the following seasonal requirements: 

• During open-water conditions, discharge is prohibited at depths greater than 1 meter 

below the surface of the receiving water between the 5 and 20-m isobaths as measured 

from the MLLW during open-water conditions or within 1000 m of river mouths or 

deltas. 

• During unstable or broken ice conditions, discharge is prohibited within 1000 m of river 

mouths or deltas or shoreward of the 20-m isobath except (1) when the discharge is 

prediluted to a 9:1 (ratio of seawater to drilling muds and cuttings), and (2) when 

environmental monitoring is conducted. 

• During stable ice conditions, unless authorized otherwise by the Director, the discharges 

shall be to above-ice locations and shall avoid to the maximum extent possible areas of 

sea ice cracking or major stress fracturing. 

In order to simplify the following analysis of the dilution and deposition of drilling muds in 

offshore waters of the Beaufort and Chukchi seas, and adjacent coastal waters, the higher 

average total drilling mud production estimate for the Chukchi Sea Area of Coverage of 598,742 

kg (1,320,000 lb), which is only 5 percent higher than the average Beaufort Sea Area of 

Coverage estimate, was used as the average total amount of drilling mud discharged to these 

waters following the completion of the average exploratory well. Because each actual 

exploratory well drilled will be unique, it can be assumed that the actual quantity of drilling 

muds produced will vary for each individual well. 

Since the dilution of the discharged mud is primarily a function of the discharge rate, and not of 

the total mass discharged, variation in the total amount of drilling muds discharged will not 

affect the predicted dilutions of dissolved and solid components in the water column. However, 

variation in the total amount of drilling mud discharged will affect the model-predicted depth of 

sediments deposited on the bottom. Therefore, the model-predicted maximum sediment depths 

for a range of total drilling muds discharged (10 to 500 percent of the average value) will also be 

explored. This will assist in the evaluation of the potential smothering effect of these various 

discharge scenarios on benthic organisms that occur within the areas (Section 5.3). 
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OOC model test cases that reflect the permit stipulations discussed above were run for openwater discharges, shunting, and below-ice discharges; results of the model runs are discussed 

below. Above-ice discharges are also discussed. 

3.1.7.1. Open-Water Discharges 

Open-water discharges were modeled for three depth and discharge combinations. OOC model 

predictions for the open-water discharge test cases are shown in Table 3-5. These test cases 

reflect the maximum discharge rates allowed by the NPDES general permit in different water 

depths - 1,000 bbl/h [159,091 liters per hour (L/h)] in water 40 m (131 ft) deep, 750 bbl/h 

(119,318 L/h) in water 20 m (66 ft) deep, and 500 bbl/h (79,545 L/h) in water 5 m (16 ft) deep. 

All model runs assume a one hour discharge of muds that have an initial solids concentration of 

1.44 kilograms per liter (kg/L) (505 lb/bbl) and a unidirectional current speed of 10 cm/s (0.33 

ft/s). 

The quantity of mud necessary to drill one average exploratory well that was used in the 

following analysis is the reported estimate for the Chukchi Sea Area of Coverage. It is estimated 

that wells drilled in the Chukchi Sea Area of Coverage will result in the discharge of 5 percent 

more drilling muds than the average well in the Beaufort Sea Area of Coverage. The quantity of 

mud is 2.6, 3.5, 5.2, and 10.4 times greater than the quantity of mud modeled for discharge rates 

of 1,000 bbl/h, 750 bbl/h, 500 bbl/h, and 250 bbl/h, respectively. [The OOC model test cases 

assume discharge durations of one hour.] 

Although the estimates of minimum solid- and dissolved-fraction dilutions will not be affected 

by the differences between modeled and actual discharge amounts, solids deposition will be 

underestimated. An estimate of the solids deposition resulting from the discharge of the quantity 

of mud necessary to drill an average, exploratory well was obtained by multiplying the OOC 

model predictions by a factor (e.g., 2.613) that represents the ratio of the total amount of mud 

discharged to the amount discharged in one hour. An explanation of this calculation, and 

calculation of the factors used in this ODCE are provided in Appendix D. This method of 

estimating mud accumulation assumes that a real deposition patterns will be unchanged for 

discharges of different quantities of mud and is reasonable provided that the rate of mud 

discharge does not vary from that predicted in the modeling. Mud deposition depths shown in 

Table 3-6 are the depths expected to occur after completion of an exploratory well. 

3.1.7.1.1. 5-meter Water Depth 

Modeling results for the maximum allowable discharge rate occurring at depths of 5 m (16.5 ft) 

show that the minimum solids dilution at 100 m (328 ft) was 7,400:1; the minimum dissolved 

dilution at 100 m (328 ft) was 356:1. The maximum depth of deposited mud was 452.4 cm 

(178.1 in) and occurred less than 10 m (33 ft) from the discharge. The mud deposition depth at 

the edge of the mixing zone was 0.32 cm (0.13 in). Approximately 98.8 percent of the 

discharged solids were deposited within the 100 m (328 ft) mixing zone (Table 3-5). There has 

been only one shallow water study (Northern Technical Services, 1983) of drilling effluent 
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disposal within the Beaufort Sea Area of Coverage. The measured dilution factors and solids 

deposition patterns in that study support the results predicted by the OOC model. 

3.1.7.1.2. 20-meter Water Depth 

Model results for maximum allowable discharge rates at a depth of 20 m (66 ft) reveal that the 

minimum solids dilution at 100 m (328 ft) was 1,326:1 and the minimum dissolved-component 

dilution at 100 m (328 ft) was 747:1. Approximately 84.4 percent of the discharged solids were 

deposited within the mixing zone, with a maximum deposition depth of 112.0 cm (44 in). The 

maximum mud depth occurred 30 m (98 ft) from the discharge; the mud depth at the edge of the 

mixing zone was 7.15 cm (2.8 in) (Table 3-5). 

3.1.7.1.3. 40-meter Water Depth 

The modeled discharge of 1,000 bbl/h (159,091 L/h) of drilling muds to waters 40 m (131 ft) 

deep caused a minimum solids dilution of 1,173:1 at 100 m (328 ft) and a minimum dissolvedfraction dilution of 1,592:1 at 100 m (328 ft). A maximum mud deposition depth of 63.9 cm 

(25.1 in) occurred 10 m (33 ft) from the discharge. The mud depth at the end of the mixing zone 

was 7.33 cm (2.9 in) and the estimated percentage of discharged solids deposited within the 

mixing zone was 39.9 percent (Table 3-5). 

3.1.7.1.4. Effect of varying total discharge on predicted-maximum sediment depth 

The drilling mud deposited on the sediment surface may physically impact benthic communities 

within the area of coverage, and the potential impact depends on the character and depth of the 

deposited solids (Section 5.3). Because the total amount of drilling mud produced by each 

exploratory well may vary somewhat about the predicted average, the model-predicted mud 

depth at the edge of the mixing zone was calculated for a range of total discharge scenarios. 

These scenarios ranged from 10 to 500 percent of the average total drilling mud discharge for a 

typical well in the Chukchi Sea area [i.e., 59,874 to 2,993,710 kg (131,000 to 6,600,000 lb) of 

drilling muds]. The depth of deposited mud for each water depth and total mud discharge was 

calculated using the appropriate conversion factor as outlined above. All open-water cases 

represent a modeled unidirectional current speed of 10 cm/s (0.33 ft/s). 

5-meter Water Depth. The model-predicted mud deposition depth at the edge of the mixing zone 

for discharge to waters 5-m deep ranged from 0.03 to 1.5 cm (0.01 to 0.59 in) (Table 3-6). Mud 

deposits of less than 1-cm depth are predicted to occur at the edge of the mixing zone for 

discharges of 1,796,226 kg (3,960,000 lb) (i.e., 300 percent of the average) or less. Mud deposits 

beyond the mixing zone are predicted to be less, and the maximum mud depth [452 cm (178 in) 

for the average total discharge] occurs within the mixing zone (Table 3-5). 

20-meter Water Depth. The model-predicted mud deposition depth at the edge of the mixing 

zone for discharge to waters 20-m deep ranged from 0.7 to 36.0 cm (0.3 to 14.2 in) (Table 3-6). 

Mud deposits of less than 1-cm depth are predicted to occur at the edge of the mixing zone for 
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discharges of 59,874 kg (132,000 lb) (i.e., 10 percent of the average). Mud deposits beyond the 

mixing zone are predicted to be less, and the maximum mud depth [112 cm (44 in) for the 

average total discharge] occurs within the mixing zone (Table 3-5). 

40-meter Water Depth. The model-predicted mud deposition depth at the edge of the mixing 

zone for discharge to waters 40 m deep ranged from 0.8 to 36.5 cm (0.3 to 14.4 in) (Table 3-6). 

Mud deposits of less than 1-cm depth are predicted to occur at the edge of the mixing zone for 

discharges of 59,874 kg (132,000 lb) or less (i.e., 10 percent of the average or less). Mud 

deposits beyond the mixing zone are predicted to be less, and the maximum mud depth [63.9 cm 

(25.2 in) for the average total discharge] occurs within the mixing zone (Table 3-5). 

3.1.7.2. Below-Ice Discharges 

Below-ice drilling mud discharges were examined with the OOC model for the same depth and 

discharge rate scenarios used when evaluating open-water discharges. However, current speeds 

for below-ice runs were reduced from the 10 cm/s (0.33 ft/s) speed used in the open-water runs 

to 2 cm/s (0.07 ft/s). OOC model predictions for the below-ice discharge test cases are shown in 

Table 3-7. Mud deposition depths shown in Table 3-8 are the depths expected to occur after 

completion of an exploratory well. 

3.1.7.2.1. 5-meter Water Depth 

The modeled maximum allowable drilling mud discharges [500 bbl/h (79,545 L/h)] into waters 5 

m (16.5 ft) deep caused a minimum solids dilution of 27,521:1 at the edge of the mixing zone 

and a minimum dissolved dilution of 972:1 at the edge of the mixing zone. A maximum mud 

depth of 487.2 cm (191.8 in) occurred less than 10 m (33 ft) from the discharge. The estimated 

mud deposition depth at the edge of the mixing zone was 0.02 cm (0.008 in); more than 99 

percent of the discharged solids were deposited within the mixing zone (Table 3-7). 

3.1.7.2.2. 20-meter Water Depth 

In waters 20 m (66 ft) in depth the modeled discharge of drilling muds at a rate of 750 bbl/h 

(119,318 L/h) caused a minimum solids dilution of 5,584:1 and a minimum dissolved dilution of 

1,052:1 at the edge of the mixing zone. A maximum mud deposition depth of 257.6 cm (101.4 

in) occurred less than 10 m (33 ft) from the discharge. An estimated 89.5 percent of the 

discharged solids were deposited in the mixing zone, with a mud deposition depth at the edge of 

the mixing zone of 0.14 cm (0.06 in) (Table 3-7). 
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3.1.7.2.3. 40-meter Water Depth 

The modeling of the maximum allowable drilling mud discharges into waters 40 m (131 ft) in 

depth caused a solids dilution of 1,552:1 and a dissolved dilution of 1,938:1 at the edge of the 

mixing zone. A maximum mud deposition depth of 67.1 cm (26.4 in) occurred 50 m (164 ft) 

from the discharge. The drilling mud depth at the edge of the mixing zone was 1.1 cm (0.43 in); 

54.6 percent of the discharged solids were deposited in the mixing zone (Table 3-7). 

3.1.7.2.4. Effect of varying total discharge on predicted-maximum sediment depth 

The drilling mud deposited on the sediment surface may physically impact benthic communities 

within the area of coverage, and the potential impact depends on the character and depth of the 

deposited solids (Section 5.3). Since the total amount of drilling mud produced by each 

exploratory well may vary somewhat about the predicted average, the model-predicted mud 

depth at the edge of the mixing zone was calculated for a range of total discharge scenarios. 

These scenarios ranged from 10 to 500 percent of the average total drilling mud discharge for a 

typical well in the Chukchi Sea Area of Coverage [i.e., 59,874 to 2,993,710 kg (131,000 to 

6,600,000 lb) of drilling muds]. The depth of deposited mud for each water depth and total mud 

discharge was calculated using the appropriate conversion factor as outlined above. All belowice cases represent a modeled unidirectional current speed of 2 cm/s (0.066 ft/s). 

5-meter Water Depth. The model-predicted mud deposition depth at the edge of the mixing zone 

for discharge to waters 5-m deep ranged from 0.002 to 0.10 cm (0.0008 to 0.04 in) (Table 3-8). 

Mud deposits of less than 1-cm depth are predicted to occur at the edge of the mixing zone for all 

percentages of the average discharge which were evaluated. Mud deposits beyond the mixing 

zone are predicted to be less, and the maximum mud depth [487.2 cm (191.8 in) for the average 

total discharge] occurs within the mixing zone (Table 3-7). 

20-meter Water Depth. The model-predicted mud deposition depth at the edge of the mixing 

zone for discharge to waters 20-m deep ranged from 0.014 to 0.70 cm (0.005 to 0.28 in) (Table 

3-8). Mud deposits of less than 1-cm depth are predicted to occur at the edge of the mixing zone 

for all percentages of the average discharge which were evaluated. Mud deposits beyond the 

mixing zone are predicted to be less, and the maximum mud depth [257.6 cm (101.4 in) for the 

average total discharge] occurs within the mixing zone (Table 3-7). 

40-meter Water Depth. The model-predicted mud deposition depth at the edge of the mixing 

zone for discharge to waters 40-m deep ranged from 0.19 to 9.5 cm (0.07 to 3.7 in) (Table 3-8). 

Mud deposits of less than 1-cm depth are predicted to occur at the edge of the mixing zone for 

discharges of 229,371 kg (660,000 lb) or less (i.e., 50 percent of the average or less). Mud 

deposits beyond the mixing zone are predicted to be less, and the maximum mud depth [67.1 cm 

(26.4 in) for the average total discharge] occurs within the mixing zone (Table 3-7). 
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3.1.7.3. Above-Ice Disposal 

The discharge of drilling muds and cuttings above ice is usually accomplished by depositing the 

effluent on the ice in large frozen chunks. It may also be spread in thin layers on the ice within 

berms to keep the disposal site intact as long as possible. Dilution and dispersion of the effluent 

occur at ice breakup. No modeling results are presented due to the lack of an adequate model for 

above-ice drilling mud disposal. Modeling of the transport and fate of muds in above-ice 

disposal sites is difficult due to the complexities of ice breakup processes. 

3.1.7.4. Shunting of Discharges 

Both open-water and below-ice discharges can be shunted (i.e., discharged at depth rather than 

near the surface). Shunting of drilling mud reduces the effective depth of the discharge, and 

therefore, reduces both the dissolved- and solids-fraction dilution. Table 3-9 provides dilution 

and deposition results obtained when using the OOC model with discharges shunted below the 

surface. Although the shunting cases modeled are not directly comparable to the other openwater and below-ice cases, they do illustrate the reduced dissolved dilutions obtained when 

discharges are shunted. The frequency of shunting during exploratory oil and gas drilling is 

unknown, as are the discharge depths that occur during shunting. However, it is likely that any 

shunting that does occur is only to a depth equivalent to the draft of the drilling ship or rig used 

(Choof, B., 3 October 1991, personal communication). The effects of shunting are likely to be 

minimal in deep waters, but may potentially be a cause of concern in shallower waters. 

3.1.7.5. Summary 

Computer modeling of drilling discharges and results obtained in other OCS areas support the 

following conclusions for drilling mud discharges in the area of coverage: 

• Drilling muds tend to be diluted rapidly following discharge. For a given discharge rate 

and mud density, the dilution is dependent on the density structure of the water column, 

the water depth, and current speed. 

• Of the three disposal methods available - open water, above-ice, and below-ice disposal - 

below-ice disposal is the least desirable due to the lesser dilution and dispersion potential 

for discharges. 

• The deposition and dilution of drilling muds for above-ice disposal has not been 

modeled; however, dilution of muds is thought to be similar or greater than that occurring 

during discharge to open-water disposal. 

• Based on OOC model results, deposition of drilling mud may exceed a depth of 1 cm (0.4 

in) outside the mixing zone for open-water discharge in water-depths from 20 to 40 

meters and surface current speeds of 10 cm/s (0.20 kn) (Table 3-5). For below-ice 
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discharges, muds deposited in excess of 1-cm (0.4-in) in depth outside the mixing zone 

may occur during discharges to water depths of 40 m. 

• Based on estimates of mud deposit depths for open-water discharge of various total 

drilling mud discharges it was determined that drilling mud deposits less than 1-cm deep 

outside of the mixing zone for surface current speeds of 10 cm/s (0.20 kn) are not 

predicted by the model for discharges to waters 40- and 20-m deep unless the total 

drilling mud discharged is reduced by 90 percent. 

• Based on estimates of mud deposit depths for below-ice discharges of various total 

drilling mud discharges it was determined that a drilling mud deposits less than 1-cm 

deep outside of the mixing zone for surface current speeds of 2 cm/s (0.04 kn) are 

predicted by the model for total mud discharges as high as 5 times the average to waters 

5-m or 20-m deep. For discharges to waters 40-m deep, mud deposits less than 1-cm 

deep beyond the mixing zone are not predicted by the model unless the total drilling mud 

discharged is reduced by 50 percent. 

• Shunting of drilling muds should be avoided in shallow waters due to the reduced 

dissolved-fraction dilution it causes. Data concerning the frequency of shunting and the 

depths at which it occurs are not available. 

3.2. CHEMICAL TRANSPORT PROCESSES 

Chemical processes include the dissolution of substances in seawater, particle flocculation, 

complexing of compounds that may remove them from the water column, redox/ionic changes, 

and adsorption of dissolved pollutants on solids. Chemical transport of drilling fluids is poorly 

described. Much must be gleaned from general principles and studies of other, related materials. 

Several broad findings are suggested, but the data for a quantitative assessment of their 

importance are lacking. Chemical transport will most likely arise from oxidation/reduction 

reactions that occur in sediments. Changes in redox potentials will effect the speciation and 

physical distribution (i.e., sorption-desorption reactions) of drilling mud constituents. 

3.2.1. Inorganics 

Most research on chemical transport processes affecting offshore oil and gas discharges focuses 

on trace metal and hydrocarbon components. The trace metals of interest in drilling fluids 

include barium, chromium, lead, and zinc. The source of barium in drilling fluids is barite; barite 

may be contaminated with several metals of interest, including arsenic, cadmium, lead, mercury, 

zinc, and other substances (Table 3-10). These trace metals are discussed below as they pertain 

to chemical transport processes. 

Kramer et al. (1980) found that seawater solubilities for trace metals associated with powdered 

barite generally result in concentrations below background levels. Exceptions were lead and zinc 

sulfides, which may be released at levels sufficient to raise concentrations in excess of ambient 

seawater levels. MacDonald (1982) found that less than five percent of metals in the sulfide 

phase are released to seawater. 
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Barite solubility in the ocean is controlled by the sulfate solubility equilibrium, which becomes 

saturated at concentrations of 30 to 40 micrograms per liter (μg/L) (Houghton et al., 1981). 

Background sulfate concentrations in seawater are generally high enough for discharged barium 

sulfate to remain a precipitate and settle to sea bottom. 

Chromium discharged in drilling fluids is primarily adsorbed on clay and silt particles, although 

some exists as a free complex with soluble organic compounds. Chromium is added to the mud 

system predominantly in the trivalent state as chrome or ferrochrome lignosulfonate, or chrometreated lignite. It may be added in the hexavalent state as a lignosulfonate extender, in the form 

of soluble chromates. The hexavalent form is believed to be largely converted to the less toxic 

trivalent form by reducing conditions downhole. The most probable environmental fate of 

trivalent chromium is precipitation as a hydroxide or oxide at pH > 5. Transformation to 

hexavalent chromium in natural waters is likely only when there is a large excess of manganese 

dioxide. Simple oxidation by oxygen to the hexavalent state is very slow, and not significant in 

comparison with other processes (Schroeder & Lee, 1975). 

Dissolved metals tend to form insoluble complexes through adsorption on fine-grained 

suspended solids and organic matter, both of which are efficient scavengers of trace metals and 

other contaminants. Laboratory studies indicate that a majority of trace metals are associated 

with settleable solids <8 μm in size (Houghton et al., 1981). 

Trace metals, adsorbed to clay particles and settling to the bottom, are subjected to different 

chemical conditions and processes than when suspended in the water column. These sorbed 

metals can be in a form available to bacteria and other organisms if located at a clay lattice edge 

or at an adsorption site (Houghton et al., 1981). If the sediments become anoxic, conversion of 

metals to insoluble sulfides is the most probable reaction, and the metals are then removed from 

the water column. Environments that experience episodic sediment previously in buried 

sediments; such current conditions also allow further exposure of organic matter complexes for 

further reduction and eventual release. 

3.2.2. Organics 

The only data generated to date on the partitioning of organics in drilling muds were generated in 

a laboratory study on admixtures of generic mud No. 8 with 5 percent high-sulfur diesel oil 

(Breteler et al., 1984). Admixture of the oil into the drilling mud resulted in recovery from the 

mixture of 42 percent (4-hour mixture) or 45 percent (10-minute mixture) of hydrocarbons 

admixed. Longer missing time (4 hours) resulted in nearly complete evaporation of the lower 

alkylated benzenes and other alkanes below C10. 

After 10 minutes of mixing and a one-hour settling time for a one percent mud/seawater mixture, 

30 percent of the hydrocarbons were in the suspended particulate phase, with five percent 

suspended and the remaining 25 percent in the aqueous phase. The aqueous phase was relatively 

enriched in C10 alkanes. Neither C1-C6 benzenes nor C10 alkanes were present in the suspended 

phase. The suspended phase was enriched in alkylated naphthalenes and phenanthrenes, except 
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for C3 phenanthrene. Suspended particulate phase (aqueous suspended) was enriched in C0-C4

(not C5 and C6) benzenes, in C0-C3 (not C4) naphthalene and in C0-C2 (not C3) phenanthrene. 

Proportionately, naphthalenes accounted for 84 percent of aromatics and 51 percent of total 

organics in the suspended phase as compared to 58 percent of aromatics and 17 percent of total 

organics (recovered) in the whole mud (10-minute mixing; 1-hour settling). Mixing for 4 hours-, 

rather than 10 minutes, decreased hydrocarbons in settleable muds from 70 percent to 20 percent 

of total hydrocarbons recovered. Aqueous phase hydrocarbon content increased from 25 to 62 

percent of the total. Particulate phase hydrocarbons increased form 5 to 18 percent of the total. 

After 4 hours, enrichment of the aqueous phase was limited to in C2-C6 benzenes and C0

napthalene, whereas the particulate phase was enriched in C1-C4 naphthalenes and in C0-C3

phenanthrenes, while alkylated benzenes were again absent from the particulate phase. 

When a 0.1 percent mud to seawater ratio was used, 10 minutes of mixing followed by one hour 

of settling resulted in recovery of 98 percent of alkylated hydrocarbons in the suspended 

particulate phase, of which only 4 percent were in the suspended phase. The suspended phase 

was enriched in C2-C4 naphthalene and in C0-C3 phenanthrenes. After 4 hours of mixing and on 

hour settling, 99.7 percent of hydrocarbons were contained in the suspended particulate phase 

with 35 percent in the suspended phase. The suspended phase was enriched in C10 n-alkanes but 

not in any other hydrocarbon. The aqueous phase, however, was enriched in C0-C3 naphthalenes 

and C0 phenanthrene. Overall recovery of aromatic hydrocarbons in this experiment, however, 

was very low, thus hindering the interpretation of these data. 

3.3. BIOLOGICAL TRANSPORT PROCESSES 

Biological processes include bioaccumulation in soft or hard tissues, biomagnification, ingestion 

and excretion in fecal pellets, and physical reworking to mix solids into the sediment 

(bioturbation). Biological transport processes occur when an organism performs an activity with 

one or more of the following results: 

• an element or compound is removed from the water column; 

• a soluble element or compound is relocated within the water column; 

• an insoluble form of an element or compound is made available to the water column; 

• an insoluble form of an element or compound is relocated. 

The most effective way to monitor the biological effects of drilling discharges is to take 

quantitative samples of the benthic infauna (animals that live on the sea floor). Sample 

variability is typically lower than that for planktonic or pelagic communities and thus sampling 

precision is higher. These animals do not move much, if at all, so they are much more 

vulnerable to the particulate fraction of fluids that accumulates on the bottom. The most 

common approach is to take replicate quantitative samples and determine whether there have 

been changes in species richness, species composition, or abundance. With six replicate 
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samples, it is possible to detect changes of 15-25 percent of the mean for numbers of species and 

25-50 percent changes in the mean abundances of some individual species. Field studies in 

Arctic Alaska did not use this approach. 

Biological transport of drilling fluids is poorly described and the information must be gathered 

from general principles and studies of other, related materials. Several broad findings are 

suggested, but the data for a quantitative assessment of their importance are lacking. 

Bioaccumulation of a number of metals from exposure to muds and mud components has been 

demonstrated in the laboratory and in the field. Short-term laboratory experiments and field 

exposures indicate that tissue enrichment factors were generally less than an order of magnitude, 

with the exception of barium and chromium. However, target organ analyses were scant and 

improper test phases were often used. Also, long-term exposures, which are particularly relevant 

to assessing impacts of development operations, have been studied; thus, a bioaccumulation 

potential for those discharges has been qualitatively demonstrated, but cannot be assed 

quantitatively at this time. 

Bioaccumulation of organics from drilling fluids, in particular those associated with (diesel or 

mineral) oils added as lubricants, has not been studied. However, such studies of these oils 

themselves or their component substances indicate that a variety of their toxic constituents can be 

bioaccumulated. Nonetheless, only a qualitative conclusion may be reached. 

3.3.1. Bioaccumulation 

Bioaccumulation is the ability of an organism to concentrate substances, including nutrients, 

naturally-occurring substances, and xenobiotics, to levels above ambient concentrations. 

Laboratory studies have shown that bioaccumulation of trace metals can be reversed, at least in 

part. When an organism is transferred from a contaminated environment to a clean one, there 

generally occurs a decrease in pollutant concentration in the organism. (USEPA, 1985) 

The majority of research on metal accumulation from drilling fluids has focused on barite 

(barium) and ferrochrome lignosulfonate (chromium). Table 3-12 provides a summary of 

laboratory data on metal accumulation discussed in the following paragraphs. Exposure to 

drilling fluids or drilling fluid components has resulted in the accumulation of barium, cadmium, 

chromium, lead, mercury, strontium, and zinc. Mercury levels were not considered in these 

studies and, therefore, data is not included in this table. 

Liss et al., (1980) examined barium and chromium accumulation in sea scallops (Placopecten 

magellanicus) by exposing them for 4 weeks to a suspension of synthetic mud equivalent to 

0.074 g/L ferrochrome lignosulfate. They found that chromium did not concentrate in the 

adductor muscle, but did concentrate in the kidney from 1.7 to 4.4 mg/kg dry weight. Exposure 

to ferrochrome lignosulfonate alone (0.1 and 0.3 g/L) resulted in 6-fold elevations of kidney 

chromium concentrations. When sea scallops were exposed to synthetic mud containing 0.55 g 

barite/L, kidney concentrations increased from less than 1.0 mg/kg dry weight to 100 mg/kg dry 

weight. Once exposure ceased, kidney chromium concentrations decreased slowly; typically less 

than 10 percent after 24 hours. 
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McCulloch et al., (1980) exposed the marsh clam (Rangia cuneata) to a layered solid phase of 

used ferrochrome lignosulfonate drilling fluid, containing 485 mg chromium/kg. Nearly half of 

the excess accumulation was lost in the first 24-hours of depuration, although no further loss 

occurred during the following two weeks. 

In a third experiment, clams and sea scallops were exposed to the mud aqueous fraction of a used 

mid-weight lignosulfonate drilling fluid (417 mg chromium/kg and 915 mg lead/kg dry weight). 

Approximately half of the excess for each metal was lost after four days depuration. When 

oyster spat (i.e., juveniles) of the species Crassostrea gigas were exposed to this same used midweight lignosulfonate drilling fluid, they exhibited soft tissue increases in chromium 

concentration of two- to three-fold in two days, and four-fold after 14 days. Lead concentrations 

in soft tissue increased two-fold after 10 days, while no detectable increase in soft tissue zinc 

concentrations was noted (McCullock et al., 1980). 

Tornberg et al., (1980) exposed arctic amphipods (Onisimus sp. and Boeckosimus sp.) to 

mixtures of used, freshwater XC-polymer drilling fluids (5 to 20 percent by volume) and water 

for 20 days. Concentrations of metals in the undiluted fluid were: cadmium - 0.5 to 1.5 mg/L; 

chromium - 66 to 176 mg/L; copper - 10 to 16 mg/L; and zinc - 49 to 110 mg/L. The greatest 

uptake occurred in the ten percent mixture occurred for cadmium, chromium, and lead, and in the 

five percent mixture for zinc. Maximum uptake relative to control organisms was five-fold for 

cadmium, and two-fold for chromium, lead, and zinc. 

A field study of bioaccumulation in organisms around a drilling operation on the mid-Atlantic 

OCS analyzed tissue data from brittle stars, polychaetes, and mollusks. Based on discharge and 

sediment analyses, the only metals exhibiting elevated tissue concentrations that were attributed 

to drilling discharges were barium and chromium (EG&G, 1982). Barium concentrations 

increased significantly from pre-drilling levels in polychaetes and brittle stars during the first 

post-drilling survey (two weeks after the completion of drilling activity); mollusks did not 

accumulate barium to an appreciable degree. Barium tissue levels dropped to pre-drilling levels 

at all stations after one year (second post-drilling survey). Average chromium and barium 

concentrations in mollusk, polychaete and brittle star tissues from pre- and post-drilling cruises 

are provided in Table 3-11. The continued increase in tissue chromium levels of all organisms 

over a year’s time indicates possible continued bioaccumulation of chromium from the low 

levels in the sediments. 

Carr et al., (1982) exposed five marine species representing three animal phyla (Arthropoda, 

Annelida, and Mollusca) to three fractions of a used lignosulfonate drilling fluid. The organisms 

showed an apparent ability to accumulate chromium from the three mud fractions. In all but two 

cases, chromium levels fell to pre-exposure levels during depuration. However, marsh clams 

(Rangia cuneata) and sandworms (Neanthes virens) accumulated chromium to levels two times 

that of the controls and retained a large fraction of the chromium for an extended period of time. 

Brannon and Rao (1979) exposed grass shrimp (Palaemonetes pugio) to 5 mg/L and 500 mg/L 

mixtures of barite in a flow-through seawater system. They analyzed for barium in the carapace 

(hard tissue), hepatopancreas, and abdominal muscle (soft tissues). They found that the shrimp 
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exposed to barite accumulated higher barium levels in their exoskeletal and soft tissues than 

control shrimp in seawater, and that the level of accumulation increased with increasing duration 

of exposure. 

Brannon and Rao also noted shrimp ingesting particulate barite and eliminating it in fecal pellets. 

This could affect fecal pellet nutritional value and sinking rate, which has ecological significance 

because fecal pellets are important in energy flow and nutrient cycling. Shrimp exposed to 

barite, in the presence of adequate strontium and calcium in the test water, were found to 

discriminate for barium and strontium relative to calcium in the hepatopancreas and abdominal 

muscle. This selective incorporation of barium into soft tissues may provide a long-term 

opportunity for barium to enter the food chain. 

In the exoskeleton, the shrimp were found to discriminate for barium and against strontium 

relative to calcium. This changed the relative mineral composition of cast exoskeletons of grass 

shrimp from calcium>strontium>barium for control organisms to calcium>barium>strontium for 

experimental organisms. Incorporation of trace metals into hard tissue can result in removal 

from the water column that is more long-term than soft tissue incorporation. Although these 

removal processes may not have toxic implications, they are pathways by which metals are 

removed from the environment. 

Chow and Snyder (1980) studied barium distribution in hard tissues of marine invertebrates 

collected from the southern California coast, and found that barium concentrations in calcareous 

exoskeletons were related to the type of organism and the mineralogical structure of the skeleton. 

Calcite skeletons of gastropods are composed of a crystal lattice that does not allow inclusion of 

the larger barium ion, whereas aragonite skeletons of mussels form a larger lattice structure 

which does allow for barium incorporation. Skeletons that incorporate other chemical 

compounds in carbonate form, such as those of the barnacle and sea urchin, allow still higher 

barium concentrations in skeletons. 

For soft tissues, Chow and Snyder (1980) indicate that the digestive tract may be the route of 

barium entry for some marine organisms. The standard deviation of barium content in various 

organs of Mytilus exhibited the following trend: stomach>gills>muscles>gonads>shells. This 

trend supports the hypothesis that the digestive tract is the route of barium entry. The trend also 

indicates that marine organisms have some degree of regulation over the incorporation of barium 

into their tissues. 

Conklin et al. (1980) note that the mechanisms of barium accumulation are poorly understood. 

There is some evidence that barium transport is mediated by a divalent-cation-activated 

adenosinetriphosphate (ATP) transport carrier as well as by micropinocytotic activity of the 

digestive epithelium. The latter hypothesis is supported by observations that grass shrimp, 

juvenile lobsters, and meiobenthic nematodes ingest particulate barite and accumulate it in their 

exoskeletons (Brannon & Rao, 1979; Chow & Snyder, 1980; Conklin et al., 1980). 

Many crustaceans have long been known to incorporate granular materials into their statocysts 

(organs of balance). The granular materials are cemented together by glandular secretions of the 

statocyst wall to form statoliths. The ectodermal inner chitinous lining and contents of the 
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statocysts (fluid, sensory hairs, and statoliths) are cast off during molting and renewed. Chow 

and Snyder (1980) confirmed that grass shrimp may incorporate sand grains, barite particles, or 

drilling mud particles into their statocysts as they renew the exoskeleton following a molt. The 

effects on the grass shrimp of this barite incorporation remains to be investigated. 

Maximal observed enrichment factors (tissue levels in exposed animals compared to control 

animal tissue levels) generally were low (1.6 to 3.4-fold), with the exception of barium (300-

fold) and chromium (36-fold). Although functional changes resulting from metal accumulation 

were not explicitly addressed in these studies, no gross, overt functional changes or potential 

alterations have been noted. 

The ability of exposed animals to clear metals accumulated during exposure to drilling fluids or 

components also have been reported. These data are summarized in Table 3-13. Depuration 

studies suggest that a substantial release of barium, chromium, lead, and strontium may occur. 

For whole animal, soft tissue, and muscle tissue analyses, 40 to 90 percent of the excess metal 

(barium, lead, chromium, and strontium) that was accumulated following 4 to 28-day exposures 

was released during 1 to 14-day depuration periods. Possibly, length of exposure and extent of 

depuration are inversely related. Transient increases were observed in chromium, lead, and 

strontium levels during the depuration period. The only sustained increase (48 percent) during 

this period occurred in chromium in scallop kidney. This finding is somewhat confounded by a 

similar trend (>24 percent) in control animals. 

These data suggest that bioaccumulation of metals as a result of drilling fluids discharges did not 

appear to be a significant problem. Yet, three factors argued against this conclusion. First, 

uptake kinetics was not adequately described, largely attributable to the rather short exposure 

periods. These exposures were most often for 14 days or less. Occasionally 16 to 28-day 

exposures occurred; in one case a 106-day exposure occurred but with only one intermediate 

value reported. The available data do not allow for any firm conclusions about the extent of 

potential uptake. Simple saturation kinetics occurs for several metals and species. However, 

complex saturation kinetics also occurs frequently. The long-term study with 106-day exposure 

did not report adequate data to characterize uptake kinetics. Since metals are highly persistent, 

long-term accumulation potential must be assessed. 

Second, the focus of these studies was often diffuse. Bioaccumulation studies should identify 

which of two toxicologic problems is being addressed: (1) human health impacts (edible tissue 

analyses) or (2) marine organism impacts (target organ analyses). Functional studies must be 

undertaken to link accumulation to adverse physiological/biochemical responses. 

Third, exposure levels were difficult to quantify in a meaningful way for correlation to field 

exposure conditions. The assessment of the bioaccumulation of drilling fluids related metals will 

be driven by the exposure of benthic epifauna and infauna to drilling fluid particulates. Yet, 

bioaccumulation studies routinely have tested whole fluids or the aqueous phase of fluids. These 

exposures could have either over-estimated or under-estimated potential accumulation. 

Furthermore, in those studies that have tested solid phase material, accumulation was only 

measured in response to a deposit layer. Therefore, no concentration-effect relationship can be 
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constructed that could estimate uptake from anything but a 100 percent exposure situation. This 

design does not lend itself to a meaningful quantitative assessment. 

In order to simulate more realistic field conditions, Neff et al. (1984) examined uptake of barium 

and chromium from the liquid settleable phase of drilling muds. Experiments included several 

species of invertebrates; clams, worms, shrimp, scallops, lobsters, and one fish (flounder). These 

experiments were performed for longer periods of time (56 to 119 days) than previous test and 

the results are consistent with previous tests. Maximum bioenrichment factors for barium and 

chromium were in the range of 2.6-16.8 for barium and 1.9-2.8 for chromium. 

While the design of these experiments was intended to simulate more realistic field conditions, 

the bioaccumulation values are compromised both by the variability of the data and, more 

importantly, by the fact that sediment barium and chromium levels decreased dramatically 

during the course of each experiment (40-80 percent for barium, 25-60 percent for chromium). 

Thus, assessing exposure in these experiments is very difficult and extrapolation to field 

conditions, in which concentrations increase during drilling, is confounded by this experimental 

design, not simplified. 

In summary, evaluation of the bioaccumulation data for drilling fluids and components has 

concluded: 

• Several metals can be accumulated, including barium, cadmium, chromium, lead, 

strontium, and zinc. Mercury is absent in the laboratory uptake data. 

• Any significant potential for adverse effects are opposed by the observations that 

enrichment factors are generally low (barium and chromium excluded), depuration 

release levels are high, and no gross functional alterations, resulting from metal 

accumulation following high exposures to drilling fluids or components, have been 

reported. 

• There are several other observations that compromise conclusion of adverse affects. Test 

results indicate that uptake kinetics is not simple, with saturation plateaus beyond the 

scope and predictive power of studies that have been conducted. Test design problems 

also contribute to equivocal interpretations and to poor utility in hazard assessment 

analyses. These design problems include: the choice of inappropriate drilling fluid 

fractions as test substances; the use of only one effective exposure concentration for fluid 

solids exposures; and the choice of tissues for analyses that are inappropriate for the 

species. 

• Metal accumulation should be considered an important area requiring further study 

because of (a) the extreme persistence of metals, (b) the elevation of sediment metal 

levels resulting from drilling discharges, (c) the notable toxicity of some of the metals 

examined (cadmium and lead), (d) the absence of laboratory data on a significantly toxic 

metal (mercury), and (e) the inability to estimate potential effects from environmentally 

realistic exposures. 
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3.3.2. Biomagnification 

Bioaccumulation relates to contaminant accumulation in a single species. If the contaminant is 

passed from prey to predator on to the next trophic level, a net increase in pollutant body burden 

up the food chain can result, and is known as biomagnification. Biomagnification is difficult to 

test experimentally and is generally assessed by comparing body burdens between organisms at 

different trophic levels. 

Little information is available to allow an assessment of biomagnification of the components of 

drilling fluid discharges. Studies have been examined, however, which assessed 

biomagnification of other inorganic and organic pollutants in various food chains. 

In an experiment to evaluate food chain transfer, sand worms were fed to flounder and lobsters, 

including worms that had been contaminated by living on barium-rich sediments and those 

which had been subsequently depurated (Neff et al., 1984). The mean barium level in 

contaminated worms was 22 μg/g, whereas the controls contained 7.1 μg/g. Chromium levels 

were 1.02 μg/g in contaminated worms and 0.62 μg/g in controls. In both cases depurated 

worms were not significantly different from controls. 

The mean enrichment in flounder and lobster muscle barium concentration was 7.2-fold. 

Flounder fed contaminated food while living on uncontaminated sediment did not accumulate 

barium in muscle tissue. There was no significant uptake of chromium in either flounder or 

lobster (USEPA, 1985). 

Type of food had no effect on mean barium concentrations in tail muscle of lobsters exposed to 

uncontaminated sediments. Lobsters living on contaminated sediments accumulated barium in 

muscle tissue when fed either uncontaminated or contaminated food. 

The above data suggests that contact with sediments may be more important in the 

bioaccumulation of barium than direct food transfer. Throughout these experiments, the metal 

content of food was highly variable. Animals may have gone through periods of uptake and 

depuration relative to this food and also the sediments on which they were living. Because of the 

timing of analyses on food (weekly) versus animals (at 56 days and 99 days), it is not possible to 

develop any direct relationship between food source and animal tissue concentrations. 

Studies of DDT and PCB organochlorine compounds reveal that accumulation of these 

compounds in the tissues of fish, mammals and birds from prey to predator occurs. Moreover, 

lipid concentrations show an increase with trophic level which indicates that dietary uptake and 

subsequent biomagnification is taking place. Studies undertaken with fish provide clear 

evidence that organochlorine uptake occurs more rapidly than does elimination, leading to 

increasing pollutant burdens with time and selective tissue accumulation at higher trophic levels 

(Fowler as cited in USEPA, 1985). However, for species at lower trophic levels, such processes 

are less clear. 

Fowler cites several studies analyzing specific food chains for organochlorine biomagnification 

with mixed results. It was suggested that these studies failed because they assumed the primary 
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organochlorine input was through the food chain, whereas recent studies indicate the water 

column may be the primary source, at least for zooplankton. Fowler speculates that plankton and 

small invertebrates accumulate substantial amounts of material from the surrounding water, and 

will reflect its composition more strongly than vertebrates, which are generally larger and have 

less surface area for absorption and, therefore, are more likely to accumulate most of their 

organochlorines from prey consumed. 

Data presented from California (Schafer et al. as cited in USEPA, 1985) concern trace metal and 

organic compound contamination in the marine environment. They examined three different 

food chains and found increasing concentrations of DDT and PCB with trophic level, but no 

evidence of increasing metal concentrations, except for organic mercury, which had a very 

strong increase. 

Most data on inorganic pollutant biomagnification show a decrease in trace metal and 

radionuclide burden with higher trophic level. However, there are exceptions found in specific 

food chains. Dog whelks were found to have three times more cadmium and four times more 

zinc than the limpets they consumed (USEPA, 1985), and subsequent depuration experiments 

showed the whelks retained these metals. However, other experimental results have shown that 

whelks did not magnify zinc or iron in contaminated barnacles upon which they were fed. 

One qualification for much of the metal data, however, is that muscle tissues were the most 

frequently sampled and analyzed. These tissues are not known to be physiological sinks for 

metal contaminants. No data have been identified that address target organ sites, such as 

hepatopancreas or kidney tissues, which would be the functional analogs to organic contaminants 

in fat and muscle tissue. Thus, the apparent difference between organics and metals may be due 

to the choice of tissue analyzed. 

Cesium-137 has been shown by Fowler to accumulate in higher trophic level fish in the food 

chain. Studies examining plutonium-237 also indicated biomagnification. However, more 

recent work has shown that the implicated organisms (starfish) rapidly absorb plutonium from 

the water and eliminate it slowly. This further indicates the importance of knowing the uptake 

pathways prior to making conclusions regarding biomagnification. 

Studies assessing biomagnification of petroleum hydrocarbons are more limited than for other 

pollutants, but the few data available suggest that these contaminants are not subject to 

biomagnification. One reason for this observation is that the primary source of these compounds 

for organisms may be absorption from the water column rather than ingestion. Also, biological 

half-times of some petroleum hydrocarbons may be short, with many species purging themselves 

within a few days (USEPA, 1985). Since the discharge of drilling muds and cuttings from 

exploratory drilling operations has little or no petroleum hydrocarbons, exposure to petroleum 

hydrocarbons would be minimal. 
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3.3.3. Ingestion and Excretion 

Organisms also remove material from suspension through ingestion of suspended particulate 

matter and excretion of this material in fecal pellets. These larger pellets exhibit different 

transport characteristics than the original smaller particles. It has been noted that filter feeding 

plankton and other organisms ingest fine suspended solids (1 μm to 50 μm) and excrete large 

fecal pellets (30 μm to 3,000 μm) with a settling velocity typical of coarse silt or fine sand 

grains. Copepods are important in forming aggregate particles. 

Zooplankton has been found to play a major role in transporting metals and petroleum 

hydrocarbons from the upper water levels to the sea bottom (Hall et al. as cited in USEPA, 

1985). The largest fraction of ingested metals moves through the animal with the unassimilated 

food and passes out with the fecal pellets in a more concentrated state (Fowler as cited in 

USEPA, 1985). Zooplankton fecal pellets have also been found to contain high concentrations 

of petroleum oil, especially those of barnacle larvae and copepods. Hall et al. calculate that a 

population of calanoid copepods grazing on an oil slick could transport three tons of oil per 

square kilometer per day to the bottom. 

3.3.4. Bioturbation 

Another pathway of biological removal of pollutants involves benthic organisms reworking 

sediment and mixing surface material into deeper sediment layers. This process is known as 

bioturbation and moves barite and clays from drilling mud to greater depths than they would 

otherwise achieve. Bioturbation can also expose previously buried material and could be an 

important facto in potential long-term impacts. No work has been found to quantify bioturbation 

effects, although a few studies have observed organisms living on a cuttings pile or in the 

vicinity of drilling discharges. However, if the environment is one which rapidly removes 

cuttings piles, or where physical forces dominate resuspension and reworking processes, then 

biological mixing activities may not prove significant. 
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4.0 BIOLOGICAL RESOURCES

This section provides an overview of the biological communities found within the Beaufort Sea, 

Chukchi Sea, Hope Basin, Norton Basin, and adjacent state waters. The general groups of 

aquatic organisms that inhabit the lease sale areas include pelagic (living in the water column), 

epontic (living on the underside or within the sea ice), or benthic (living on or within the bottom 

sediments) plants and animals. The categories of offshore biological environment that will be 

discussed include: 

• Plankton 

• Attached macro- and microalgae 

• Benthic invertebrates 

• Fishes (demersal and pelagic) 

• Marine mammals 

• Coastal and Marine birds 

• Threatened and Endangered Species 

• Essential Fish Habitat 

Each of these biological resources is assessed in terms of seasonal distribution and abundance, 

growth and production, environmental factors, critical areas or habitats, and effects from 

exploration related discharges. An analysis of the cumulative effects of the discharges to 

biological resources is provided in Section 4.9. Mitigation measures are provided in Section 

4.10. Assumptions for the effects analysis include: 

• Exploratory oil and gas well drilling activities produce a wide range of waste that is 

discharged into receiving waters. The types of material discharged during exploratory 

operation mainly include drilling muds and cuttings, but also include sanitary and 

domestic wastes, desalination unit wastes, boiler blowdown, test fluids, deck drainage, 

blowout preventer fluids, uncontaminated ballast and bilge water, excess cement slurry, 

compounds used for equipment and drilling maintenance activities, non-contact cooling 

water, and fire control system test water. Discussion of these discharges is provided in 

Section 2.0 of this evaluation. Based on the small quantity of discharges, other than 

muds and cuttings, and the permit limitations imposed on them, it is unlikely that they 

will impact the marine environment or any listed species. 

• Exploratory discharges are not likely to exceed applicable water quality criteria outside of 

a 100 m radius (~1,000 m area) around each drilling discharge site. 

• In most continental shelf areas, drilling muds and cuttings land on the sea bottom within 

1,000 m of the discharge point. 

• Exploration activities are fairly temporary and are widespread throughout the Area of 

Coverage. 
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• Exploratory oil and gas drilling generates a wide range of waste materials related to the 

drilling process, equipment maintenance, and personnel housing. These materials are 

commonly discharged directly from the rig into the receiving water. Discharges of 

primary concern to this evaluation are drilling fluids, also called drilling muds, and 

cuttings. Drilling muds are the fluids used to lubricate the drill bit and stem and to 

remove waste rock particles (“cuttings”) that are brought up from the hole during the 

drilling operation. 

• Components of potential concern in drilling muds include trace metals and specialty 

additives used with generic drilling mud systems. Drilling muds can adversely affect 

marine life provided exposures are sufficiently long and concentrations sufficiently high. 

Effects can occur due to chemical toxicity, clogging of feeding or respiratory structures 

with particulates, smothering, and modifications of habitat. Because drilling discharges 

are episodic and typically only a few hours in duration, organisms that live in the water 

column are not likely to have long-term exposures to drilling muds. 

• The most toxicologically important constituents of drilling muds are aromatic compounds 

and heavy metals. The NPDES permit incorporates a standard acute toxicity test using 

the mysid Mysidopsis bahia. Under these permits, discharge of muds with a LC50 of less 

than 30,000 ppm SPP (suspended particulate phase) is prohibited. Drilling mud toxicity 

data compiled by USEPA, Region-l0, from Alaskan exploratory and production wells 

indicate that the muds used in all current and recent operations are acutely toxic only to a 

slight degree to Mysidopsis bahia. Only 7 of the 91 tests had a LC50 less than the 30,000 

ppm limit. 

• Water quality standards for the state of Alaska are met at the edge of a 100-meter radius 

mixing zone. 

Some impacts may be measurable, but their effects may be minimal and/or short-term in 

duration; therefore, they may not require avoidance or mitigation. Adverse impacts that are 

reduced by mitigation below the “significance thresholds” that are incorporated into the permit, 

or that are demonstrated to be acceptable because the risk of the impact occurring is small, are 

considered “nonsignificant.” For this evaluation, “significance threshold” is defined for each 

resource as the level of effect that equals or exceeds the adverse changes indicated in the 

following impact situations: 

• Biological Resources (seals, walrus, beluga whale, polar bear, marine and coastal birds, 

terrestrial mammals, lower trophic-level organisms, fishes, essential fish habitat, and 

vegetation and wetlands): An adverse impact that results in a decline in abundance and/or 

change in distribution requiring three or more generations for the indicated population to 

recover to its former status and one or more generations for polar bears. 

• Threatened and Endangered Species (bowhead whale, spectacled and Steller’s eiders): 

An adverse impact that results in a decline in abundance and/or change in distribution 

requiring one or more generation for the indicated population to recover to its former 

status. 
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4-3 

4.1. PLANKTON 

Plankton can be divided into two major classes: phytoplankton and zooplankton. Plankton are 

vital components of the pelagic plankton community as they provide the food base for other 

groups of marine organisms found within the Arctic Area of Coverage. The distribution, 

abundance, and seasonal variation of these organisms are strongly influenced by the physical 

environment. 

4.1.1. Phytoplankton 

4.1.1.1. Distribution and Abundance 

The predominant phytoplankton species in Arctic Alaska waters are diatoms. One species, 

Nitzschia cylindrus, predominates in both open water and epontic habitats (MMS, 1991). 

Chaetoceros sp. has also been identified as an abundant component of the phytoplankton (MMS, 

1991). In studies done in Harrison and Prudhoe Bays, flagellates were most numerous at the 

surface with diatoms most numerous in the water column. Microflagellates may occasionally be 

the most abundant group in offshore waters. 

Phytoplankton spatial distribution is variable and patchy, although distribution for most species 

is widespread. The spacial distribution (horizontal) of diatoms in waters close to shore and river 

mouths suggest that light levels, rather than salinity or temperature, determine diatom 

distribution (ADNR, 1999). 

The abundance of phytoplankton in the Beaufort Sea is generally greatest in nearshore waters, 

with decreasing abundance noted further offshore (MMS, 1990). Peak abundance in late July 

and early August follows the breakup of winter ice and the peak in solar light intensity. 

4.1.1.2. Growth and Production 

The growth rates of planktonic organisms are relatively rapid, and the generation lengths are 

relatively short. For example, the body weight doubled every 2 weeks among immature stages 

of the common mysid, Mysis litoralis, during summer 1977-1978 field studies in Simpson 

Lagoon, and the generation length was 1-2 years (MMS, 2003). The rapid growth rates also 

were evident during formation of typical summer “blooms” during 1977 and 1978. 

Phytoplankton production is limited primarily by available nutrients, particularly nitrogen, and 

light. The most productive area of the Arctic Alaska waters is the coastal zone. Primary 

productivity was highest not at the surface, but in the water column where diatoms were the most 

abundant organism. Phytoplankton production gradually increases after ice break-up, when light 

becomes available. Then it declines after September when light availability limits 

photosynthesis. Peak primary production varies by as much as two to three times between years 

and depends on the relative amount of summer ice cover (Homer, 1984). The presence of a 
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seasonal spring phytoplankton bloom immediately following ice breakup has not been firmly 

established (Homer, 1984; Schell et al., 1982). However, this may be due to the limited data 

available on phytoplankton concentrations when ice is still present (due to logistical sampling 

difficulties) to detect a spring bloom. 

In the southern Chukchi Sea, primary production is enhanced by the transport of upwelled 

nutrient-rich water from the Gulf of Anadyr in the northwestern Bering Sea through the Bering 

Strait and into the Chukchi Sea. An area of intense productivity, nearly twice the production of 

the southeastern Bering Shelf, occurs in the region near St. Lawrence Island and northward 

through the Bering Strait. Primary productivity tends to decrease in the northerly direction from 

the Bering Strait. 

Primary productivity in Inner Norton Sound is low due to turbidity from the sediment load 

carried by the Yukon River. Primary productivity of Outer Norton Sound is high; there are 

intense phytoplankton blooms each year associated with the spring retreat of the ice sheet. 

4.1.1.3. Environmental Factors 

The major environmental factors influencing phytoplankton growth are temperature, light and 

nutrient availability. Phytoplankton growth is usually limited to the photic zone, or the depth to 

which sunlight penetrates the water. Light, as influenced by ice regimes, and nutrients are both 

important in determining levels of primary production. 

The phytoplankton provides the food base for a variety of secondary producers including 

herbivorous zooplankton (Figure 4-1). Rapid increases of phytoplankton stock in open water 

deplete nutrient concentrations in the upper water column, resulting in production being 

nitrogen-limited during the summer (MMS, 1991). While increased phytoplankton populations 

provide more food to organisms at higher trophic levels, too much phytoplankton can harm the 

overall health of the water body. During these blooms, most of the phytoplankton die and sink to 

the bottom, where they decompose. This process depletes the bottom waters of dissolved oxygen, 

which is necessary for the survival of other organisms.

4.1.1.4. Critical Areas or Habitat 

At present no important habitats or areas can be identified.
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4.1.2. Zooplankton

4.1.2.1. Distribution and Abundance

More than 100 species of zooplankton have been identified in Arctic Alaska waters. Copepods 

are the dominant zooplankton group, both in terms of numbers and biomass (MMS, 1990). 

Other components of zooplankton include amphipods, mysids, euphausiids, chaetognathes, 

ostracods, pteropods, ctenophores, and larval stages of benthic and nektonic organisms. 

Zooplankton can be found in the sunlit zone and in deep ocean waters. Zooplankton abundance 

and species diversity appears to increase with increasing distance from shore. 

4.1.2.2. Growth and Production

The growth rates of planktonic organisms are relatively rapid, and the generation lengths are 

relatively short. For example, the body weight doubled every 2 weeks among immature stages 

of the common mysid, Mysis litoralis, during summer 1977-1978 field studies in Simpson 

Lagoon, and the generation length was 1-2 years (MMS, 2003). The rapid growth rates also 

were evident during formation of typical summer “blooms” during 1977 and 1978. 

The currents moving north through the Bering Strait exert a strong influence on Chukchi Sea 

primary and secondary productivity due to the transport of nutrients, detritus, phytoplankton, 

zooplankton, and larval forms of invertebrates and fishes from the Bering Sea to the Chukchi 

Sea. Seasonal ice regimes also influence the spatial and temporal variation of primary 

productivity. 

Zooplankton standing stock generally fluctuates in response to phytoplankton production. 

Productivity within the Beaufort and Chukchi Seas decreases from nearshore to offshore waters 

and is considerably less than the productivity observed in comparable depths in the Bering Strait. 

4.1.2.3. Environmental Factors

Most copepods are primarily herbivorous, so copepods form an important link between 

phytoplankton and larger, carnivorous species, including species of whales that feed on pelagic 

zooplankton (e.g., bowhead whale) (Figure 4-1). 

Zooplankton, like phytoplankton, make excellent indicators of environmental conditions because 

they are sensitive to changes in water quality. They respond to low dissolved oxygen, high 

nutrient levels, toxic contaminants, poor food quality or abundance and predation 
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4.1.2.4. Critical Areas or Habitats 

Zooplankton abundance is generally lower in the Chukchi Sea than in more southerly areas 

(Hope and Norton Basins). However, zooplankton communities have been described as being 

richer in the Chukchi Sea and western part of the Beaufort Sea than in the eastern Beaufort Sea 

(east of approximately Barter Island) (MMS, 1990). At present no important habitats or areas 

have been identified. 

4.1.3. Effects Analysis 

An extensive review found no evidence of effects on plankton from drilling muds (Neff, 1991). 

Based on the 1,000-meter seafloor area that might be affected temporarily by drilling discharges, 

plankton in the Area of Coverage probably would not be affected. During exploratory drilling, 

muds and cuttings are typically discharged onto sea ice. This silty material, similar to riverine 

overflow sediments, may block sunlight and reduce photosynthesis of plankton in the water 

column; however, the area of impact would be limited to the immediate vicinity of the drill site. 

These cuttings are carried out to sea with the drifting pack ice after spring break-up. 

4.2. ATTACHED MACROALGAE AND MICROALGAE 

4.2.1. Macroalgae 

4.2.1.1. Distribution and Abundance 

Macroalgae show a distinct and fixed pattern of vertical distribution in their habitat. Some of 

these plants inhabit the coast above high water mark, whereas others populate the intertidal zone 

or the sublittoral zone. Macroalgae populations occur naturally, but an increase in their biomass 

(especially if it is associated with a decrease in seagrass) may also be an indication of 

deteriorating water quality. Macroalgal biomass is most commonly limited by dissolved 

inorganic nitrogen, but can also be limited if high light attenuation prevents adequate light 

reaching the bottom. 

The distribution of kelp is limited by three main factors: ice gouging, sunlight, and hard 

substrate. Ice gouging restricts the growth of kelp to protected areas, such as behind barrier 

islands and shoals. Sunlight restricts the growth of kelp to the depth range where a sufficient 

amount penetrates to the seafloor, or water less than about 11 m deep. Hard substrates, which 

are necessary for kelp holdfasts, also restrict kelp to areas with low sedimentation rates. 

Macroalgae are also unlikely to occur in shallow water and areas lacking a rocky substrate. 

However, benthic algae have been noted in areas where rock substrates were lacking, but these 

algal beds did not contain the diverse epilithic fauna that characterized areas with suitable rocky 

substrate (Dunton et al., 1982). 
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Attached macroalgae (primarily kelp) occur in state waters in nearshore and offshore barrier 

island areas containing suitable rocky substrate for attachment. Dunton et al. (1982) reported on 

the occurrence of kelp beds along the coastal areas of the eastern Beaufort Sea. Concentrated 

areas of kelp have been noted in state waters of the Beaufort Sea at Steffansson Sound (Boulder 

Patch), Stockton Islands, Belvedere and Flaxman Islands, Demarcation Bay, Elson Lagoon near 

Point Barrow, near Konganevik Point in western Camden Bay, and Nuvagapak Lagoon. 

Macroalgae concentrations along the Chukchi Seacoast not been frequently encountered in the 

Chukchi Sea, possibly due to the lack of adequate substrates (rock, cobble, and gravel). Kelp 

beds have been noted about 20 km northeast of Peard Bay near Skull Cliff and in an area 25 km 

(13.5 nmi) southeast of Wainwright in water depths of 11 to 13 m (MMS, 1991). 

Macroalgal communities are typically dominated by the kelp, Laminaria sp. Studies of the 

Boulder Patch algal community indicated the predominance of the kelp, Laminaria solidungula, 

but red algae and a diverse assemblage of benthic invertebrates were also noted (MMS, 1990). 

Macroscopic red and green algae have also been noted in Peard Bay of the Chukchi Sea (Truett, 

1984a). 

4.2.1.2. Growth and Production 

Arctic kelp grows fastest in late winter and early spring due to higher concentrations of inorganic 

nitrogen in the water column (ADNR, 1999). Sediments trapped in the ice above the kelp block 

light and restrict growth while the presence of leads and cracks has the opposite effect (ADNR, 

1999). 

4.2.1.3. Environmental Factors 

Kelp beds provide a three-dimensional environment that provides a diverse habitat for attached 

microalgae, invertebrates, and fish. However, relatively few invertebrates (all polychaetous 

annelids and arthropods) and only six species of fish were noted in conjunction with the algae at 

Skull Cliff (MMS, 1991). 

Kelp at Boulder Patch was estimated to contribute half of the annual primary carbon production 

(Dunton, 1984). Approximately 60 percent of the particulate organic carbon released to the 

environment originates from kelp which may be an important source of carbon to secondary 

producers in the community (Dunton, 1984). The only herbivore that noticeably consumes kelp 

in Boulder Patch is the chiton (Amicula vestita) (Dunton, 1984). 

4.2.1.4. Critical Areas or Habitats 

All likely kelp habitats have not yet been surveyed. Other kelp habitats may be discovered, as 

portions of the Area of Coverage are further explored. The areas of concentrated macroalgal 
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growth that have been identified include Skull Cliff, Steffansson Sound (Boulder Patch), 

Stockton Islands, Flaxman Island, Demarcation Bay, and Elson Lagoon, which may be 

considered important habitats or areas. Phillips and Reiss (1985) have also reported a large kelp 

bed approximately 25 km (13.5 nmi) southwest of Wainwright in water depths of 11 to 13 m (36 

to 43 ft). This kelp bed may be a critical area for various populations within the area. 

4.2.2. Microalgae 

The microalgae consist primarily of pennate diatoms and microflagellates, but centric diatoms 

and dinoflagellates may also be present (Homer & Schrader, 1982). 

While the mechanism of photosynthesis in microalgae is similar to that of higher plants, they are 

generally more efficient converters of solar energy because of their simple cellular structure. In 

addition, because the cells grow in aqueous suspension, they have more efficient access to water, 

CO2, and other nutrients. 

4.2.2.1. Distribution and Abundance 

Attached microalgae occur in the epontic community of both state waters and the open marine 

waters of the Beaufort and Chukchi seas. 

In general, attached microalgae are most likely to occur in areas not subjected to ice gouging and 

land fast ice, and where hard substrates suitable for attachment occur (MMS, 1990). However, 

benthic algae have been noted in areas where rock substrates were lacking, but these algal beds

did not contain the diverse epilithic fauna that characterized areas with suitable rocky substrate 

(Dunton et al., 1982). 

Benthic microalgae occur in sediments and within the macroalgal communities. Benthic 

microalgae may be a significant source of primary productivity in nearshore areas, but in areas of 

kelp production, the contribution of benthic microalgae may be relatively small. Dunton (1984) 

estimated that benthic microalgae contributed about 2 percent of the annual carbon produced in 

the Steffansson Sound Boulder Patch. 

4.2.2.2. Growth and Production 

Light appears to be the limiting factor which controls the distribution, deve1opment, and 

production of the ice-algal assemblage (MMS, 1990). The ice-algal bloom usually occurs in 

April and May and occasionally in early June, while the open water phytoplankton bloom does 

not occur until ice breakup is underway. 
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4.2.2.3. Environmental Factors 

These algae are the primary food source for a variety of animals, including amphipods, 

copepods, ciliates, various worms, and juvenile and adult fishes (MMS, 1991) 

(Figure 4-2). 

Epontic microalgae were estimated to contribute 25 percent of the annual carbon production at 

Boulder Patch (Dunton, 1984). 

4.2.2.4. Critical Areas or Habitats 

The distribution of microalgal communities bas been noted as patchy on both large and small 

scales (MMS, 1991), and no important critical habitats or areas can be identified at present. 

4.2.3. Effects Analysis 

The types of material discharged during exploratory operations usually include drilling muds and 

cuttings, although there are restrictions on these discharges in shallow water, under ice, and near 

special kelp communities. Although the permit allows for a 100-m zone of potential 

contamination, there is no evidence of the effects on kelp and seaweed. Smothering of species 

within the 1,000-m seafloor area would occur and would have adverse affects to species. 

However, recovery of the affected benthic communities likely would occur within 1-2 years after 

the termination of discharges. 

Drilling muds can adversely affect marine life provided exposures are sufficiently long and 

concentrations sufficiently high. Effects can occur due to chemical toxicity, clogging of feeding 

or respiratory structures with particulates, smothering, and modifications of habitat. The most 

toxicologically important constituents of drilling muds are aromatic compounds and heavy 

metals. 

The benthic community in the immediate vicinity of the drilling discharge is the most likely to be 

impacted because of exposure to large amounts of drilling muds and cuttings. The results of the 

OOC model case runs indicate that benthic communities outside the prescribed 100-m mixing 

zone could be adversely impacted because they would receive greater than 1 cm of deposited 

solids. 

It is not possible to accurately predict the area within the proposed area of coverage which would 

receive deposition amounts detrimental to benthos, because of the uncertainty of drilling rig 

locations and because deposition depends on site-specific oceanographic conditions. If it is 

assumed that a deposition depth of 1 cm (0.4 in) would be detrimental to benthic organisms, a 

worst-case scenario calculation indicates that less than 0.0001 percent of the total area proposed 
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for exploration by MMS and ADNR would potentially be adversely impacted. Solids deposition 

exceeding 1 cm (0.4 in) in thickness may be expected for a variety of drilling scenarios, 

including water depths of 5, 20, or 40 m (16.5, 66, or 131 ft., respectively) in both open-water 

and below-ice settings. 

Uncertainty exists regarding the long-term toxicological effects of drilling muds and cuttings 

deposited on the seafloor. Of particular concern are the impacts arising from chronic leaching of 

metals, hydrocarbons, and the most persistent biocides in drilling muds and cuttings deposited on 

the bottom. In addition, insufficient evidence exists to demonstrate that data from short-term 

acute toxicity tests reveal subtle adverse effects at the ecosystem level of biological complexity 

(Parrish & Duke, 1990). 

4.3. BENTHIC INVERTEBRATES 

Benthic invertebrates are organisms that live on the bottom of a water body (or in the sediment) 

and have no backbone. The size of benthic invertebrates ranges from microscopic (e.g., 

microinvertebrates ,<10 microns) to a few tens of centimeters or more in length (e.g., 

macroinvertebrates, >50 cm). Benthic invertebrates live either on the surface of bedforms (e.g., 

rock, coral or sediment - epibenthos) or within sedimentary deposits (infauna), and comprise 

several types of feeding groups (e.g., deposit-feeders, filter-feeders, grazers and predators). The 

principal benthic invertebrates found in the Area of Coverage include oligochaete worms, 

isopods, mysids, amphipods, bivalves, priapulids, chironomid larvae, dipterans, and hermit crabs 

(Broad et al., 1978). 

4.3.1. Distribution and Abundance 

The distribution, abundance, and seasonal variation of benthic species in the Arctic Alaska 

waters are strongly correlated with physical factors (e.g., substrate composition, water 

temperature, depth, dissolved oxygen concentrations, pH, salinity, sediment carbon/nitrogen 

ratios, and hydrography). Larger invertebrate communities are found in nearshore lagoons. 

These communities include animals living in the bottom (infauna), animals living on or near the 

bottom (epibenthic), and those which live in the water column (pelagic). During winter, 

epibenthic and pelagic species disappear, and then emerge again in spring, whereas infauna and 

some amphipods may be present year-round (ADNR, 1999). 

In nearshore waters with depths less than 2 m (6.6 ft), relatively few species are found because 

the ice in this region extends all the way to the seafloor during winter. Therefore, the abundance 

of most species is probably dependent on annual (or more frequent) colonization. Biomass and 

diversity in the inshore zone generally increase with depth, except in the shear zone between 

approximately 15 to 25 m (49 to 82 ft). Intensive ice gouging occurs in this zone, which disturbs 

the sediments and presumably limits the abundance of infaunal species (Braun, 1985). 

In order of decreasing numerical abundance, polychaetes (Ampharete vega and Terebellides 

stroemi), bivalves (Cyrotidaria durriana), and small crustaceans (principally amphipods) are the 

most abundant infaunal organisms on the continental shelf and slope of the Beaufort Sea (Carey 
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et al., 1974, pp. 565-680; Carey & Ruff, 1977, p. 510; Carey, 1978, p. 160). Carey et al. (1974) 

reported that polychaete worms comprised up to 85 percent of the infauna at stations sampled on 

the Beaufort Sea continental shelf. 

Common epibenthic creatures (epifauna) found within the area include amphipods, mysids, the 

isopod Saduria entomon, the shrimps Sabinea septemcarinata and Sclerocrangon boreas, and 

the crabs Chionoecetes opilio (tanner crab) and Hyas coarctatus; pelagic species include 

copepods and chaetognaths. Together with euphausiids, and planktonic amphipods, they 

constitute a substantial portion of the invertebrate biomass, especially in inshore areas. 

Populations of nearshore and inshore motile epifauna do not appear to differ between the 

Beaufort Sea, Chukchi Sea, and the eastern Bering Sea (Broad, 1979, p. 371; Stoker, 1981). In 

offshore areas, echinoderms are important contributors to the total biomass. 

The species composition and biomass of the Chukchi Sea is strongly controlled by the input of 

nutrients and organic matter from the productive waters of the Gulf of Anadyr through the 

Bering Strait into the Chukchi Sea (Feder et al., 1989). Two major faunal assemblages have 

been identified by Stoker (1981) for the Chukchi Sea: one group is dominated by the polychaete 

Maldane sarsi, the echinoderm Ophiura sarsi, the sipunculid Golfingia margaritacea, and the 

bivalve Astarte borealis; the second group is dominated by the bivalves Macoma calcarea, 

Nucula tenuis and Yoldia hyperborea, and the amphipod Pontoporeia femorata. These areas, in 

turn, served as significant foraging areas for the bottom-feeding gray whales and walrus (Feder 

et al., 1989). 

Among epifaunal invertebrates, echinoderms seem to dominate (Frost & Lowry as cited in 

Truett, 1984b, p. 136). Brittle stars (usually Ophiura sarsi,) are particularly abundant in areas 

with muddy substrate. Other associated species include soft corals (Eunephthya sp.) and sea 

cucumbers (Psolus sp. and Cucumaria sp.). Epibenthic species abundance and distribution are 

typically quite variable within the shallow water lagoons near the Chukchi Sea Area of 

Coverage. 

In nearshore waters with depths less than 2 m (6.6 ft), relatively few species are found. During 

winter, the ice in this region extends all the way to the seafloor; therefore, the abundance of most 

species is probably dependent on annual (or more frequent) colonization. Biomass and diversity 

in the inshore zone generally increase with depth, except in the shear zone between 

approximately 15 to 25 m (49 to 82 ft). Intensive ice gouging occurs in this zone, which disturbs 

the sediments and presumably limits the abundance of infaunal species (Braun, 1985, p. 67). Ice 

gouging continues out to about 40 m (131 ft) with decreasing intensity. Diversity and biomass of 

infauna increase beyond this zone with distance offshore, at least as far as the continental shelf 

boundary [200 m (656 ft)] (MMS, 1990). Few data are available regarding the benthic 

community inhabiting deeper waters within the Beaufort Sea Planning Area; therefore, it is not 

possible to identify the important species in this region or their distributions and abundances. 
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4.3.2. Growth and Production 

Studies of the northeast Chukchi Sea by Feder et al. (1989) indicated that the supply of organic 

matter from the Bering Sea supplied the sediments with organic matter that resulted in areas of

relatively higher benthic productivity. 

4.3.3. Environmental Factors 

The abundance, diversity, biomass, and species composition of benthic invertebrates can be used 

as indicators of changing environmental conditions. The biomass of benthic invertebrates 

declines if communities are affected by prolonged periods of poor water quality especially when 

anoxia and hypoxia are common. Benthic communities can change in response to: 

• nutrient enrichment leading to eutrophication; 

• bioaccumulation of toxins to lethal levels in molluscs (shellfish), crustaceans, polychaetes 

and echinoderms, and cause the loss of herbivorous and predatory species; 

• lethal and sub-lethal effects of heavy metals and other toxicants derived from oil and gas 

activities; 

• dislodged epifauna and infauna from trawling and dredging which may result in the 

collection and mortality of a substantial invertebrate bycatch; 

• the replacement of the existing benthic community with other benthic species due to 

physiological stress and/or by competition or predation by species better physiologically 

suited to the modified conditions; and 

• changes in the physical and biological characteristics and structure of habitats (i.e., their 

function), including supporting habitat such as seagrass meadows and sandy soft bottom 

areas. 

Burrowing and tube-building by deposit-feeding benthic invertebrates (bioturbators) helps to mix 

the sediment and enhances decomposition of organic matter. Nitrification and denitrification are 

also enhanced because a range of oxygenated and anoxic micro-habitats are created. Loss of 

nitrification and denitrification (and increased ammonium efflux from sediment) in coastal 

systems is an important cause of hysteresis, which can cause a shift from clear water to a turbid 

state. The loss of benthic suspension-feeding macroinvertebrates can further enhance turbidity 

levels because these organisms filter suspended particles including planktonic algae, and they 

enhance sedimentation rates through biodeposition (i.e. voiding of their wastes and unwanted 

food). 
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Changes in the macrofauna (and flora) causes changes in nutrient storage pools and in the flux of 

nutrients between microfauna (and flora) and macrofauna and flora. Macrofauna are also 

important constituents of fish diets and thus are an important link for transferring energy and 

nutrients between trophic levels and driving pelagic fish and crustacean production. It is for these 

reasons and others, that benthic invertebrates are extremely important indicators of 

environmental change. 

The nearshore waters provide habitat for a variety of benthic organisms which in turn serve as an 

important food source for birds and fishes that utilize state waters for feeding, spawning, and 

nursery areas. The primary prey organisms for fish, mammals [including gray whales 

(Eschrichtius robustus), beluga whales (Delphinapterus leucas), and walrus (Odobenus 

rosmarus divergens)], and birds are the motile pelagic organisms and motile benthic epifauna 

(Figure 4-2). 

4.3.4. Critical Areas or Habitats 

Because of the disturbance from grounded ice, most of the benthic species in the Area of 

Coverage are small and widely distributed, like small clams and mobile epibenthic amphipods. 

The area known as Boulder Patch (located in Steffanson Sound near the Sagavanirtok River) is 

recognized as an important benthic habitat, primarily due to habitat provided by hard substrates 

and associated algal beds. This area lies within the adjacent state waters of the areas of 

coverage. 

4.3.5. Effects Analysis 

Many benthic invertebrates are relatively sedentary and sensitive to environmental disturbance 

and pollutants. Drilling muds can adversely affect marine life provided exposures are 

sufficiently long and concentrations sufficiently high. Effects can occur due to chemical 

toxicity, clogging of feeding or respiratory structures with particulates, smothering, and 

modifications of habitat. The most toxicologically important constituents of drilling muds are 

aromatic compounds and heavy metals. 

Overall, larvae and planktonic organisms are apparently the most sensitive to drilling discharges, 

and effects on them will primarily be a function of dilution and dispersion of the discharge 

plume. It is unlikely that the chemical toxicity of drilling muds will substantially impact pelagic 

organisms near exploratory drilling sites because concentrations of toxic constituents are 

estimated to be below levels known to be acutely lethal at the edge of the 100-m (328 ft) mixing 

zone. 

The benthic community in the immediate vicinity of the drilling discharge is the most likely to be 

impacted because of exposure to large amounts of drilling muds and cuttings. Little information 

is presently available concerning the effects of various deposition depths on benthic 

communities. Most studies that have investigated deposition impacts on benthos have examined 

deposition of dredged materials (Hale, 1972; Kranz, 1974; Mauer et al., 1978; Oliver & Slattery, 
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1973; Saila et al., 1972; Schafer, 1972; Schulenberger, 1970; Wilber, 1992). These studies 

indicate that the response to deposition and survival following such an event is species-specific. 

Of the species examined, burial depths from which organisms were able to migrate to the surface 

ranged from 1 to 32 cm (0.4 to 12.6 in). If it is assumed that most benthos are not adversely 

affected by deposition of drilling muds less than 1 cm, benthos in the vicinity of the discharge 

receiving deposition in excess of this amount may be acutely impacted by drilling activities. 

The results of the OOC model case runs indicate that benthic communities outside the prescribed 

100-m mixing zone could be adversely impacted because they would receive greater than 1 cm 

of deposited solids. 

It is not possible to accurately predict the area within the proposed area of coverage which would 

receive deposition amounts detrimental to benthos, because of the uncertainty of drilling rig 

locations and because deposition depends on site-specific oceanographic conditions. If it is 

assumed that a deposition depth of 1 cm (0.4 in) would be detrimental to benthic organisms, a 

worst-case scenario calculation indicates that less than 0.0001 percent of the total area proposed 

for exploration by MMS and ADNR would potentially be adversely impacted. Solids deposition 

exceeding 1 cm (0.4 in) in thickness may be expected for a variety of drilling scenarios, 

including water depths of 5, 20, or 40 m (16.5, 66, or 131 ft, respectively) in both open-water 

and below-ice settings. 

Uncertainty exists regarding the long-term toxicological effects of drilling muds and cuttings 

deposited on the seafloor. Of particular concern are the impacts arising from chronic leaching of 

metals, hydrocarbons, and the most persistent biocides in drilling muds and cuttings deposited on 

the bottom. In addition, insufficient evidence exists to demonstrate that data from short-term 

acute toxicity tests reveal subtle adverse effects at the ecosystem level of biological complexity 

(Parrish & Duke, 1990). 

The quantity of benthic organisms preyed upon by other species could be reduced in the area of 

the discharge if benthos migrate from the area, or experience increased mortality or decreased 

recruitment, through smothering, toxicity, or alteration of sediment grain size characteristics. 

The degree of food supply reduction caused by discharges of drilling muds and cuttings is 

unknown, as the size of the affected area and severity of impacts are by necessity speculative. 

However, a significant reduction of food supplies (benthic organisms) is judged unlikely, given 

that under a worst-case scenario, only a small portion of the Area of Coverage (approximately 

0.0001 percent of the area) would receive deposition depths greater than 1 cm (0.4 in). 

Benthic organisms near Beaufort Sea drilling sites have not been found to accumulate petroleum 

hydrocarbons or heavy metals (Brown, Boehm & Cook as cited in MMS, 2003). Based on the 

1,000-m seafloor area that might be affected temporarily by drilling discharges, less than one 

percent of the benthic organisms in the Area of Coverage probably would be affected. Benthic 

organisms within 1,000 m of a platform would likely experience temporary sublethal effects with 

some lethal effects on immature stages due to trace metals in drilling muds. Within this distance, 

some changes would likely occur in the species composition of affected benthic areas. Recovery 

of the affected benthic communities likely would occur within 1-2 years after the termination of 

discharges. 
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Norton Sound supports a rich benthic community which plays a key role in an extended food 

chain supporting a wide range of marine mammals. Any disruption of this benthic base could 

seriously affect the biota of the entire region. 

4.4. FISHES 

The fishes occurring in the Arctic Alaska waters fall into three basic categories (MMS, 2003): 

1) freshwater species that may occasionally enter marine waters, 2) anadromous species that 

spawn in freshwater and migrate seaward as juveniles and adults, and 3) marine species that 

complete their entire life cycle in the marine environment. Fish species likely to be found in the 

Area of Coverage are listed in Table 4-1. 

4.4.1. Distribution and Abundance 

Sixty-two species of fish have been collected from the coastal waters of the Alaskan Beaufort 

Sea (69% marine, 26% migratory, 5% freshwater). Thirty-seven species were collected in the 

warmer nearshore brackish waters, and 40 species were collected in the colder marine waters 

farther offshore (some use both habitats). Seventy-two species of fish were reported for the 

northeastern Chukchi Sea (MMS, 1991). 

The physical environment, mainly temperature and salinity, of the Arctic waters exerts a strong 

influence on the temporal and spatial distribution and abundance of fish (MMS, 1990, 1991). 

The Chukchi Sea represents a transition zone between the fish communities of the Beaufort and 

Bering Seas (MMS, 1991); the fauna is primarily Arctic with continual input of southern species 

through the Bering Strait (Craig, 1984). Marine fish in the Chukchi Sea are generally smaller 

than those in areas farther south, and densities are much lower (Frost and Lowry, 1983). The 

lower diversity, density, and size of fish in the region have been attributed to low temperatures, 

low productivity, and lack of nearshore winter habitat due to ice formation (MMS, 1987b). 

During the open-water season, the nearshore zone of this area is dominated by a band of 

relatively warm, brackish water that extends across the entire Alaskan coast. The summer 

distribution and abundance of coastal fishes (marine and anadromous species) is strongly 

affected by this band of brackish water. The band typically extends 1-6 miles offshore and 

contains more abundant food resources than waters farther offshore. The areas of greatest 

species diversity within the nearshore zone are the river deltas. As the summer progresses, the 

amount of freshwater entering the nearshore zone decreases, and nearshore waters become colder 

and more saline. From late summer to fall, migratory fishes move back into rivers and lakes to 

overwinter and to spawn (if sexually mature). In winter, nearshore waters less than 6 feet deep 

freeze to the bottom. Before they freeze, marine fishes continue to use the nearshore area under 

the ice but eventually move into deeper offshore waters with the advancement of landfast ice. 

The freshwater environment of the Alaska Coastal Plain consists of rivers, streams, lakes, ponds, 

and a maze of interconnecting channels. While some of these waterbodies are completely 

isolated, most are permanently, seasonally, or sporadically connected. Seasonally connected 

lakes are flooded during breakup, while sporadically connected lakes are flooded only during 
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high-water years (MMS, 2003). The distribution and abundance of freshwater and migratory 

fishes depend on (1) adequate overwintering areas, (2) suitable feeding and spawning areas, and 

(3) access to these areas (typically provided by a network of interconnecting waterways) (MMS, 

2003). 

Since the presence of freshwater species is generally sporadic and brief within the Area of 

Coverage, there is little information regarding distribution and abundance, although it can be 

derived that these species would be found near river deltas and bays in nearshore waters; juvenile 

fishes prefer the warmer shallow-water habitats that become available during the open-water 

period (MMS, 2003). The most abundant freshwater fish is the ninespine stickleback (Hemming 

in MMS, 2003). The highest numbers are found in waters having emergent and submerged 

vegetation suitable for spawning and rearing, with overwintering sites nearby (Hemming as cited 

in MMS, 2003) 

Anadromous fish typically leave the rivers and enter the nearshore waters during spring break-up 

in June. As the ice cover melts and recedes, these fish will migrate along the coast; smaller fish 

tend to stay near the mouths of rivers while larger fish may migrate distances of 80 mi or more in 

search of feeding habitat (ADNR, 1999). Migration back to rivers varies by species, but most 

anadromous fish return to freshwater, where they spawn and overwinter, by mid-September 

(ADNR, 1999). 

Whitefish spend much of their life cycle feeding in salt water during the summer and generally 

remain in freshwater plumes extending out from river mouths and in marine waters of lower 

salinity (ADNR, 1999). 

Cisco are among the most abundant anadromous fish in bay and delta areas. They inhabit the 

nearshore environment and spawn in the fall. 

Salmon (anadromous species) are uncommon in the North Slope region and thought to be strays 

by most researchers, although pink and chum salmon have been reported throughout the 

Chuckchi Sea. The presence of salmon is rare in the Beaufort Sea coastal waters, particularly 

east of the Colville River. While the occurrence of salmon east of the Colville River is rare, 

small numbers of pink salmon occasionally have been taken in the Sagavanirktok River and 

Colville River and in some drainages west of the Colville River. However, both species do not 

have established populations and spawning is not known to have occurred anywhere in this area 

(MMS, 2003). It is possible that random small schools of pink salmon from western stocks 

spawn in the Sagavanirktok River on a chance basis. In recent years, chum smolts have been 

caught in the lower delta (MMS, 2003). Small runs also may occur in rivers closer to Barrow. 

Small numbers of chum are taken in the Chipp River and in Elson Lagoon, including adults in 

spawning condition (MMS, 2003). 

Marine species appear to be widely distributed but in fairly low densities; schooling species (e.g., 

arctic cod) display a rather patch distribution (ADNR, 1999). Some marine species sporadically 

enter the nearshore areas to feed and spawn while others remain in coastal waters throughout the 

open-water season then move farther offshore with the advancement of the landfast ice during 

winter. 
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The most widespread and abundant marine species are the arctic cod, saffron cod, twohorn and 

fourhorn sculpins, the Canadian eelpout, and the arctic flounder (MMS, 1987a). Additionally, 

Arctic staghorn sculpin, shorthorn sculpin, and hamecon are abundant species in the Chuckchi 

Sea. Common marine fishes in the nearshore area include fourhorn sculpin, yellowfin sole, and 

capelin (MMS, 1987b, 2003). Saffron cod, arctic flounder, and snailfish also use the nearshore 

area; however, their occurrence is sporadic and variable, and they are found in much lower 

numbers. Arctic flounder, starry flounder, and fourhorn sculpin are generally found in the lowsalinity waters near estuaries and river mouths. Common marine fishes in waters farther 

offshore include arctic cod, arctic staghorn sculpin, kelp snailfish, capelin, shorthorn sculpin, 

twohorn sculpin, hamecon, and Canadian eelpout (MMS, 1987a, 2003). Despite the large 

quantity of benthos in Norton Sound, bottomfish are less abundant there than in the other 

Alaskan regions in the Area of Coverage.

Arctic cod are infrequent visitors to nearshore habitats during the first portion of the open-water 

season when waters are warmest and salinities are low (Craig et al. as cited in MMS, 2003). 

Arctic cod have been found to be more concentrated along the interface between the warmer 

nearshore water and colder marine water. 

Fourhorn sculpin are among the most widespread and numerous species along the Beaufort Sea 

coastline. This demersal fish is found in virtually all nearshore habitats, including deeper waters 

not frequented by anadromous fishes. 

Saffron cod, arctic flounder, and starry flounder have similar distributions; however, their 

occurrence is sporadic and variable and they are present in much lower numbers (MMS, 1987a). 

Canadian eelpout is a benthic fish species that is common on muddy bottoms. Twohorn sculpin 

is found offshore and is abundant but patchy in its distribution (ADNR, 1999). 

Capelin is a widely distributed species that has been reported in areas west of the Mackenzie 

Delta. It is only abundant during August when it spawns in coastal habitats (MMS, 1987a). 

4.4.2. Growth and Production 

A lack of overwintering habitat is the primary factor limiting arctic fish populations (ADNR, 

1999). 

Ocean growth of pink salmon is a matter of considerable interest because, although this species 

has the shortest life span among Pacific salmon, it also is among the fastest growing. Entering 

the estuary as fry at around 3 cm in length, maturing adults return to the same area 14-16 months 

later ranging in length from 45 to 55 cm. 

Spawning in the arctic environment can take place only where there is an ample supply of 

oxygenated water during winter. Because of this and the fact that few potential spawning sites 
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can meet this requirement, spawning often takes place in or near the same area where fishes 

overwinter (MMS, 2003). 

The timing and location for spawning by marine fish varies. Capelin spawns in coastal areas in 

August. Fourhorn sculpin spawn on the bottom in nearshore habitats during midwinter. 

Snailfish also spawn in midwinter by attaching their eggs to rocks or kelp. Arctic cod spawn 

under the ice between November and February in both shallow state waters and in offshore 

waters (MMS, 1990). 

4.4.3. Environmental Factors 

Because the feeding habits of marine fishes are similar to those of anadromous fishes, some 

marine fishes are believed to compete with migratory fishes for the same prey resources. 

Competition is most likely to occur in the nearshore brackish-water zone, particularly in or near 

the larger river deltas. 

Infaunal prey density in the nearshore substrate is very low and provides little to no food for 

anadromous fishes. However, prey density in the nearshore water column is high, about five 

times that of freshwater habitats on the Arctic Coastal Plain. The nearshore feeding area also is 

much larger than that of freshwater habitats on the coastal plain (MMS, 2003). For these 

reasons, both marine and anadromous fishes come to feed on the relatively abundant prey found 

in nearshore waters during summer. 

In late summer when anadromous fishes are less abundant and their prey is more abundant, 

dietary overlap is common in nearshore waters (MMS, 2003). Marine birds also compete for the 

same food resources during this time. Anadromous fishes do little to no feeding during their 

migration back to freshwater and when spawning, but some resume feeding during winter. 

In the marine environment, pink salmon fry and juveniles are food for a host of other fishes and 

coastal sea birds. Subadult and adult pink salmon are known to be eaten by fifteen different 

marine mammals, sharks, other fishes such as Pacific halibut, and humpback whales. Because 

pink salmon are the most abundant salmon in the North Pacific, it is likely they comprise a 

significant portion of the salmonids eaten by marinemammals. 

Marine species feed heavily on epibenthic and planktonic crustacea such as amphipods, mysids, 

isopods, and copepods. Bottom fish, including flounders, also feed on bivalve mollusks and 

fourhorn sculpins also feed on juvenile Arctic cod (MMS, 1990). Except for Arctic cod and the 

leatherfin lumpsucker (Eumicrotremus derjugini - which feed mainly on zooplankton), all other 

offshore fish species rely heavily on benthic invertebrates, particularly amphipods and 

polychaetes (MMS, 1984). 

The arctic cod has been described as a key species in the ecosystem of the Arctic Ocean due to 

its widespread distribution, abundance, and importance in the diets of marine mammals, birds, 

and other fishes. It is considered to be the most significant consumer of secondary production in 
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the Alaska Beaufort Sea and may influence the distribution and movements of marine mammals 

and seabirds. 

4.4.4. Critical Areas or Habitats 

The Colville River is a major overwintering area for cisco and other anadromous fish species 

(ADNR, 1999). During the open-water period, cisco undertake extensive migrations through the 

nearshore area (ADNR, 1999). Most marine species spawn in shallow coastal areas during the 

winter. The warmer nearshore zone with its more moderate salinity is thought to be an essential 

nursery area for juvenile arctic cod (Cannon, Glass, & Prewitt as cited in MMS, 2003). Fourhorn 

sculpin spawn on the bottom in nearshore habitats during midwinter (ADNR, 1999). Snailfish 

attach their eggs to rocks or kelp stubstrates in nearshore waters (MMS, 1987a). 

Pink salmon and rainbow smelt use larger river systems and estuaries in the area, such as the 

Kokolik, Utukok, Kukpowruk, and Kuk, as spawning and rearing areas (Fechhelm et al., 1984, p. 

236). These rivers all flow into the Chukchi Sea between Wainwright and Point Lay. 

Because of the key role Arctic cod play in the food chain of the Chukchi Sea, any identified 

spawning habitats could be considered critical areas. Although Arctic cod are known to spawn 

in the winter under the ice, most of their spawning areas are unknown (Morris, 1981). Arctic cod 

are most often found around pressure ridges and rafted ice, where the undersurface of the ice is 

rough (MMS, 1991). Typical habitats include crevices, holes, caverns, and small ice cracks. 

Pacific herring spawn in the subtidal regions of Norton Sound using marine vegetation such as 

Focus kelp and Zoestra eelgrass. High spawning densities of pacific herring are common at 

Bluff, from Cape Darby to Moses Point, Norton Bay, Cape Denbigh-Arctic Hills, and the area to 

the east of 164° W, east of the St. Michael and Stuart Islands (Barton as cited in MMS, 1982). 

4.4.5. Effects Analysis 

Discharges of drilling muds and cuttings may have potential toxic effects. Water quality tests 

indicate that lethal concentrations are generally present only within a few meters of the discharge 

point (USEPA, 1985). The effect on fish depends on the dilution of the discharge. In shallow 

depths with poor circulation, the effect is a reduction on benthic populations. Little effect was 

noted in depths of 66 ft or shallower with dissipating tidal or current action. Discharges in 

shallow, ice-covered waters are presently restricted; therefore, the likelihood that fishes would be 

exposed to discharges during their critical overwintering period for relatively long periods of 

time in areas of little circulation is reduced. 

While no specific demersal fish spawning locations have been identified in any of the Arctic 

areas of coverage, a number of important species, including most cottids and eelpout, possess 

demersal eggs. Although unlikely during exploratory activities in the Area of Coverage due to 

the anticipated emphasis on deeper offshore drilling sites, demersal eggs could be smothered if 

discharge in a spawning area coincides with the period of egg production. Exploratory 

operations in state waters are more likely to adversely impact demersal fish spawning activities 
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because spawning grounds are more commonly found in nearshore waters. The potential of 

drilling muds and cuttings to smother demersal fish eggs is probably the most serious potential 

impact of exploratory drilling to fish species. 

Drilling mud disposal is not expected to affect the major prey, zooplankton, or fish or their 

habitats. Discharges of drilling fluids and drilling cuttings may impact minor prey, benthic 

organisms (at sublethal levels), and benthic habitat, which in turn will impact critical habitat for 

fish species. Drilling discharges could displace fishes a short distance from the source however, 

the effects would be localized and temporary. However, the impact areas are small (less than 

100-m radius) per discharger, the number of discharges is small (23 exploration wells and 14 

delineation wells), and the recovery period of impacted benthos is less than two years. It is 

expected that fishes would re-utilize their habitat upon completion of the exploration activities. 

4.5. MARINE MAMMALS 

Marine mammals in the Area of Coverage include polar bears, walrus, and species of seals and 

whales. Common species include: spotted, ringed, and bearded seals; beluga, killer, and gray 

whales; polar bear; and walrus. Species of marine mammals that are protected by the 

Endangered Species Act (ESA) within in the Area of Coverage will be discussed in Section 4.7. 

At least 12 other species of marine mammals (including minke whales, Baird’s beaked whales, 

harbor porpoise, narwhal, and hooded seal, fur seals, ribbon seals) are found occasionally or 

rarely in the Area of Coverage. 

All marine mammals in U.S. waters are protected under the Marine Mammal Protection Act of 

1972. In the act, it was the declared intent of Congress that marine mammals “be protected and 

encouraged to develop to the greatest extent feasible commensurate with sound policies of 

resource management, and that the primary objective of their management should be to maintain 

the health and stability of the marine ecosystem.” The polar bear is also protected by an 

international treaty (i.e., International Agreement on the Conservation of Polar Bears of 1976 

between Canada, Denmark, Norway, the former U.S.S.R, and the U.S.). 

4.5.1. Distribution and Abundance 

Year-round residents in the area of coverage include ringed and bearded seals and polar bears; 

seasonal summer species include the beluga whale and the spotted seal. Gray whales and walrus 

also reside seasonally within the Beaufort Sea, most often in areas west of Barrow. Most of the 

marine mammals occurring in the Chukchi Sea can be grouped into two categories: 1) baleen 

whales that use the area as summer feeding grounds, and 2) pinnipeds (seals and walrus) that are 

ice-associated during the winter and also reproduce during that time. 

As described in MMS (1991), ice distribution determines the timing and route of migration for 

whale species, as well as the location of seals, polar bear, and walrus. Years of heavy ice will 

delay migration, depending on circumstances, and may redistribute seal and bear populations. 

Because marine mammal species are often quite mobile, it is difficult to predict the exact 

location of animal concentrations or to predict populations at any given time or location. A 
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seasonal distribution of marine mammals in the northeastern Chukchi Sea is summarized below 

(Morris, 1981, pp. 56-57). Some species of pinnipeds occur in great abundance in the Chukchi 

Sea, with densities as high as 2-3 seals/km2

 not uncommon in the landfast-ice zone (MMS, 

1991). 

Winter/Spring Pack Ice: polar bear 

Flaw Zone: beluga whale, bearded seal, polar bear 

 Fast Ice: ringed seal, polar bear 

Summer/Autumn Pack Ice: ringed seal 

 Pack Edge: walrus, polar bear, bearded seal, beluga whale 

Open Water: (migration routes) walrus, seals, gray whale, beluga 

whale 

Coastal Lagoons: beluga whale, spotted seal 

Note: The flaw zone is that region between the pack ice and the fast ice where polynyas (open-water leads) are 

commonly found. 

Some baleen whales are more abundant now than they were at the close of the commercial 

whaling period, but less abundant than their historical level (MMS, 1991). The eastern Chukchi 

Sea stock was estimated at a minimum of about 3,700 whales (Ferrero et al. as cited in MMS, 

2003). 

The Beaufort Sea beluga whale population was currently estimated to be in excess of 32,000 

whales (Ferrero et al. as cited in MMS, 2003). Most of this population migrates from the Bering 

Sea into the Beaufort Sea in April or May; however, some whales may pass Point Barrow as 

early as late March and as late as July (MMS, 2003). An estimated 2,500-3,000 belugas summer 

in the northwestern Beaufort and Chukchi Seas; some use coastal areas. Fall migration back to 

the Bering Sea occurs in September and October along offshore pack-ice, although a small 

number have been observed migrating along the coast. 

Since receiving protection by the International Whaling Commission in 1946, the eastern Pacific 

gray whale population has increased from a few thousand individuals that survived commercial 

harvest to more than 21,000 (MMS, 2003). The current minimum gray whale estimate is 26,635 

with an estimated annual increase rate from 1967/1968-1995/1996 at 2.4% (Ferrero et al. as cited 

in MMS, 2003). A portion of the gray whale population summers along the west coast of North 

America south of the Bering Sea/Unimak Pass (56 FR 58870). Gray whales migrate into the 

northern Bering and Chukchi seas starting in late April through the summer open-water months 

and feed there until October-November (MMS, 2003). They migrate out of the Chukchi and 

Beaufort seas with freezeup and migrate out of the Bering Sea during November-December 

(Rugh & Braham as cited in MMS, 2003). Most whales occur within 15 km of land but have 
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been observed up to 200 km offshore (Bonnell & Dailey as cited in MMS, 2003). Much of the 

migration route north of Point Conception to and from summer feeding grounds in the northern 

Bering and southern Chukchi seas lies within a few kilometers of the coast or adjacent islands. 

Nearly all gray whale observations were west of Point Barrow, and few gray whales were seen 

east of Barrow (MMS, 2003). 

The distribution of polar bears (Ursus maritimus) is strongly influenced by the state of sea ice 

and its effect on the distribution of prey (i.e., seals). The Beaufort Sea (from Point Barrow to 

Cape Bathurst) polar bear population has been estimated to be 1,300 to 2,500 individuals (U.S. 

Fish & Wildlife, 1993). The Southern Beaufort Sea’s population (from Icy Cape to Cape 

Bathurst, Northwest Territories, Canada) is about 1,800 bears (Gorbics, Garlich-Miller, & 

Schliebe as cited in MMS, 2003). The current stock assessment is 2,272 and a minimum 

estimate of 1,971 bears (Federal Register March 28, 2002). This population has increased over 

the past 20-30 years at 2% or more per year and is believed to be increasing slightly or 

stabilizing near its carrying capacity (Amstrup; US Fish & Wildlife Service as cited in MMS, 

2003). Their seasonal distribution and local abundance vary widely in the Alaskan Beaufort Sea. 

Amstrup, Durner, and McDonald (2000) assumed a bear density of one bear per 25 square 

kilometers occurs in seasonal concentration areas. Much lower densities occur beyond 100 miles 

offshore and higher densities near ice leads, where seals concentrate during the winter. Another 

study estimated their overall density from Point Barrow to Cape Bathurst as one bear every 141-

269 square kilometers (54-103 square miles) (Amstrup, Stirling, & Lentfer as cited in MMS, 

2003). Polar bears enter the Norton Sound region in the fall with advancing ice and usually 

penetrate the Bering Sea no further south than St. Lawrence Island (MMS, 1982). Occasionally 

polar bears summer on St. Lawrence Island. The approximate number of polar bears which 

occur in the Norton Basin is unknown. 

The ringed seal (Phoca hxspida) is the smallest and most abundant seal in the Beaufort and 

Chukchi Seas. Ringed seals live on or near the ice year-round; therefore, the seasonal ice cycle 

has an important affect on their distribution and abundance (ADNR, 1999). More recently, 

surveys were flown perpendicular to the Alaskan coast from Shishmaref to Barrow during MayJune 1999 and 2000 (Angliss & Lodge, 2002). Preliminary results from the 1999 survey indicate 

that the total abundance in the area surveyed was estimated at 245,048 (Angliss & Lodge, 2002). 

About 1.0 to 1.5 million ringed seals inhabits the Bering and Chukchi Seas (MMS, 1982). In 

winter, highest densities of ringed seals occur in the stable shorefast ice. 

Spotted seals are found in large numbers along the Bering Sea and Chukchi Sea coasts; they are 

common in bays, estuaries, and river mouths and are particularly concentrated from Kasegaluk 

Lagoon to the mouth of the Kuk River and Peard Bay (MMS, 1991). Spotted seals haul-out 

along the coast of the Beaufort Sea in July in relatively low numbers (about 1,000 for the 

Alaskan Beaufort Sea coast). Beaufort Sea coastal haulout areas include the Colville River delta, 

Peard Bay, and Oarlock Island in Dease Inlet/Admiralty Bay, and spotted seals have recently 

frequented Smith Bay at the mouth of the Piasuk River (MMS, 1990) (see Graphic 2, MMS, 

1990). They migrate out of the Beaufort Sea from September to mid-October as the landfast ice 

reforms and spend the winter and spring periods offshore north of the 200-m isobath along the 

ice front throughout the Bering Sea, where pupping, breeding, and molting occur (Lowry et al., 
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2000). The Bering Chukchi population of spotted seal ranges from 280,200 go 330,000. Major 

population segments migrate through outer Norton Sound during spring and fall (MMS, 1982). 

The majority of the bearded seal (Erignathus barbatus) population in Alaska is in the Bering and 

Chukchi seas. The sex ratio of Alaska samples consistently show slightly more females in the 

population (ADNR, 1999). This species usually prefers areas of less-stable or broken sea ice, 

where breakup occurs early in the year (Cleator & Stirling as cited in MMS, 2003). In the 

Beaufort Sea, the bearded seal is primarily restricted to moving pack-ice from July through 

October (MMS, 1996). Estimates on the abundance of bearded seals in the Beaufort Sea and in 

Alaskan waters currently are unavailable; however, the minimum population in Alaskan waters 

is expected to be at least 50,000 animals (Ferrero et al. as cited in MMS, 2003). From 300,000 to 

450,000 bearded seals inhabits the Bering and Chukchi Seas (MMS, 1982); densities are highest 

from late November through late June. 

The North Pacific walrus is most commonly found in relatively shallow water areas, close to ice 

or land. Spring migration from the Bering Sea usually begins in April; most of the walruses 

move north through the Bering Strait by late June. The majority of the walrus population occurs 

west of Barrow, although a few walrus may move east throughout the Alaskan portion of the 

Beaufort Sea to Canadian waters during the open water season. Walrus are very abundant in the 

Chukchi Sea during the summer; over 100,000 individuals, or 40 percent of the North Pacific 

population, can be found there (Sease & Chapman, 1988). Of this number, most are pregnant 

females and their dependent young. About 80 percent of the world population (160,000 to 

200,000) occurs seasonally in the Bering Sea. During seasonal transition periods, walrus 

densities are greatest in outer Norton Sound. Calves are born during the northward migration in 

spring in outer Norton Sound. A substantial number of the mature males remain in the Bering 

Sea year-round (Fay, 1982). Solitary animals occasionally overwinter in the Chukchi Sea and 

eastern Beaufort Sea, but most of the population migrates south of the Bering Strait in the fall 

(October-December) with the southern advancement of pack-ice (Fay, 1982). In the last 20 

years, the walrus population has increased rapidly and extended its range (Fay & Kelly, 1980). 

There are indications (i.e., decreases in physical fitness) that the carrying capacity of the 

environment may have been exceeded by the increased walrus abundance (Fay et al., 1984). 

4.5.2. Growth and Production 

Beluga whale calving is reported to occur in Norton Bay near Moses Point. 

Polar bears breed during April and May. Males travel long distances during this time searching 

for females. When a female is found, the male will stay with her for a few days to breed and 

then will leave in search of other females. Cubs are born during December and January. 

Normally the female has two cubs and may produce only one or two litters during her life (every 

three to four years). 

Ringed seals breed in winter and spring and give birth to a single pup in March and April. 

Spotted seals are annual breeders and mating occurs in late April to early May. Pupping occurs 
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anytime from early April to the first part of May with the peak season being the first two weeks 

of April. 

The ability for bearded seals to conceive successfully usually occurs when females are five to six 

years old. Males become sexually mature at six or seven years. Bearded seals commonly 

become reproductively active before they attain maximum growth. The incidence of pregnancy 

in adult females is about 85 percent (ADNR, 1999). Females bear a single pup during late April 

or early May. Pupping takes place on top of the ice less than 1 m from open water (Kovacs, 

Lyderson, & Gjertz as cited in MMS, 2003) from late March through May mainly in the Bering 

and Chukchi seas, although some takes place in the Beaufort Sea. By the end of a brief nursing 

period (12 to 18 days), pups increase their weight almost three times, mainly due to an increase 

in thickness of the blubber layer (ADF&G as cited in ADNR, 1999). 

The gross reproductive rate of walruses is considerably lower than that of seals. Prime 

reproductive females produce one calf every 2 years rather than one every year, as do other 

pinnipeds. Most female walrus do not begin to breed until six or seven years of age. Mating 

occurs from January through March, but growth of the fetus does not begin until about mid-June. 

Walrus caves are born mostly in mid-April to mid-June during the spring migration. Calves are 

dependent upon their mothers for at least 18 months and occasionally for as long as 2-1⁄2 years. 

4.5.3. Environmental Factors 

Gray whales migrate into the Chukchi and Beaufort Seas during spring to feed throughout the 

late spring, summer, and early fall. Gray whales are primarily suction-bottom feeders and 

primarily ingest benthic gammaridean amphipods (MMS, 1991). However, gray whales have 

also been observed feeding on dense swarms of pelagic euphausids (Guerrero as cited in MMS, 

1991). 

Beluga whales feed on a variety of organisms, including arctic and saffron cod, capelin, herring, 

squid, whitefish, char, and various benthic invertebrates in nearshore waters (MMS, 2003). The 

majority of the eastern Pacific gray whale population feeds primarily on benthic amphipods; they 

suck infauna amphipods from the fine sand on the ocean bottom, producing an extensive record 

of feeding craters 2-20 square meters (m2

) in size (MMS, 2003). 

For polar bears, successful denning, birthing, and rearing activities require a relatively 

undisturbed environment. During early November and December, the pregnant females search 

out deep, south-facing snow drifts in which to dig their dens (ADF&G as cited in ADNR, 1999). 

Polar bear denning can occur on both land and on sea ice. Dens found on land are usually within 

six miles of the coastline; dens on the ice may drift up to 600 mi during the winter. Research 

indicates that bears do not den in the same place, but are only faithful to the general substrate and 

geographic area upon which they had previously denned (e.g., on-ice vs. on land). Based on 

radio collar surveys, the Beaufort Sea population dens locally, and is not dependent on 

reproduction from other known denning areas outside of the region (Amstrup & Gardner as cited 

in ADNR, 1999). 
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Polar bears are opportunistic feeders, but prey primarily on subadult ringed and bearded seals, 

and walruses, but they also feed on walruses, small whales, birds, seaweed, eggs, berries, 

lemmings, shrubs, lichens, grass, carrion, human refuse, garbage and occasionally other polar 

bears and humans (MMS, 1991, 1993). Hunting polar bears concentrate near open leads in 

winter. A polar bear has to catch approximately one seal a week to maintain itself. The mother 

does not eat while denning; both she and her cubs live off her fat reserves. 

Seals feed primarily on pelagic fishes and invertebrates; the particular species eaten depends on 

availability, depth of water, and distance from shore. Ringed seals spend much of the summer 

and early fall in the water feeding; the important food species for ringed seals are Arctic cod, 

saffron cod, shrimps, and other crustaceans (ADNR, 1999). Spotted seals eat a varied diet; there 

are geographical and seasonal differences in their prey. Principal foods for spotted seals are 

schooling fishes and along the coast they feed on herring, capelin, saffron cod, some salmon 

(especially in lagoons and river mouths) and smelt (ADF&G as cited in ADNR, 1999). The 

bearded seal mainly feeds on crabs, shrimp, clams and snails (ADF&G as cited in ADNR, 1999). 

Walruses feed primarily on bottom dwelling invertebrates by brushing the sea-bottom with their 

brad, flat muzzles. Major food items include bivalve mollusks. Other food items include snails, 

crabs, shrimp, worms, and occasionally seals (ADNR, 1999). 

4.5.4. Critical Areas or Habitats 

The adjacent state waters of the Beaufort and Chukchi seas provide important habitat areas for a 

variety of marine mammals. These areas include denning areas for polar bears, haulout areas for 

walrus and species of seals, and feeding areas for gray and beluga whales. 

A major portion of the Beaufort Sea beluga whale population concentrates in the Mackenzie 

River estuary during July and August. Beluga whales are known to calve and may molt in 

Kasegaluk lagoon and Peard Bay (MMS, 2003). 

Shallow coastal areas and offshore shoals in the Chukchi and western Beaufort seas provide rich 

benthic feeding habitat for gray whales during November-December (Rugh et al. as cited in 

MMS, 2003). Gray whale feeding areas offshore of northern Alaska are characterized with low 

species diversity, high biomass, and the highest secondary production rates reported for any 

extensive benthic community (Rugh et al. as cited in MMS, 2003). Most gray whale 

observations were west of Point Barrow, and few gray whales were seen east of Barrow (MMS, 

2003). 

Polar bear dens are found in a variety of regions including the Jones Island group, offshore and 

barrier islands, shorefast ice, along river banks, and far offshore on the pack ice (MMS, 1991). 

An important habitat zone is in the eastern Beaufort Sea at the seaward edge of the landfast ice 

corresponding roughly with the 66-ft isobath (Stirling as cited in ADNR, 1999). Most denning is 

concentrated on offshore barrier islands and certain portions of the mainland (MMS, 1990); areas 

receiving consistent use include Wrangell Island, Russia, and in Hudson Bay and James Bay, 
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Canada. Polar bear dens have also been located on river banks in northeast Alaska and on 

shorefast ice close to islands east of the mouth of the Colville River. 

Landfast ice provides optimum habitat for ringed seal lair construction and supports the most 

productive pupping areas (Kelly, 1988). Regions of landfast ice are found in the southeastern 

corner of the Chukchi Sea Area of Coverage. 

During the summer, two large Arctic areas are occupied by the walrus: from the Bering Strait 

west to Wrangell Island and along the northwest coast of Alaska from about Point Hope to north 

of Point Barrow. Although the Pacific walrus is associated with moving pack-ice, a coastal 

walrus haulout area east of Cape Lisburne in the Chukchi Sea was identified (MMS, 1990). 

Herds of migrant walrus appear on Big Diomede, King, St. Lawrence, and the Punuk Islands in 

fall during movements into the area from the Chukchi Sea. Outer Norton Sound could be 

considered a calving area for the walrus. 

4.5.5. Effects Analysis

Heavy metals in Beaufort Sea marine mammals and their prey are the focus of an ongoing study 

at the Univerity of Alaska Fairbanks (Dehn et al., 2002). The study found differences in the total 

mercury in the livers of ringed and bearded seals from the Alaskan and Canadian Arctic. They 

suggested that those differences were related to differences in the prey, because ringed seals eat 

mostly pelagic organisms (i.e., euphausiids) and bearded seals eat benthic and epibenthic 

organisms. The variations were observed over broad regions of the arctic rather than near and 

far from areas in which there had been discharges. 

4.6. COASTAL AND MARINE BIRDS 

Migratory birds are a significant component of the marine ecosystem of the Area of Coverage. 

These areas comprise foraging, nesting, and rearing areas for several million birds. Species of 

coastal and marine birds that are protected by the ESA within in the Area of Coverage will be 

discussed in Section 4.7. 

Of the several million birds are found in Area of Coverage, about 70 species occur regularly in 

the Beaufort Sea area and 85 species in the Chukchi Sea area. Most of these species are 

migratory and only present in the Arctic seasonally, from May through early November. Some 

species appear only during migration; others nest, molt, feed, and accumulate critical fat reserves 

needed for migration while in the area (MMS, 1987a). The main categories of species in the 

Area of Coverage include waterfowl (e.g., duck, goose, swan), seabirds (e.g., loon, gull, tern), 

shorebirds (e.g., sandpiper, plover, crane), and raptors (e.g., hawks, eagles, falcons). A complete 

list of all bird species within these groups for the Area of Coverage is presented in Tables 4-2 

through 4-5. 
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4.6.1. Distribution and Abundance 

Aerial surveys in the Beaufort Sea have documented that birds are widespread in substantial 

numbers in both nearshore and offshore waters of the Area of Coverage (MMS, 2003) and it is 

likely that approximately this distribution prevails along most or all of the Beaufort coastline and 

into the northern Chukchi Sea during the open-water season. 

Birds occur out to at least 70 km offshore where open water is available, although bird densities 

generally are lower in offshore areas. Offshore, the highest bird density is associated with openwater leads, where more than 1 million eiders may congregate (MMS, 1991). The highest 

pelagic bird density is located between Barrow and Cape Halkett, which lies within the area. 

This is probably due to the infusion of Bering Sea water in this area, which contains high 

amounts of plankton that provide a food source for birds as well as other organisms. 

Most avian species migrate eastward along a broad front, which may include inland, coastal, and 

offshore routes; arrival dates for various species range from late April to early June (MMS, 

2003). The availability of open water off river deltas and in leads determines migratory routes 

and distribution of waterfowl and seabirds. Raptors are present in the Area of Coverage during 

the spring, summer, and fal. 

The Beaufort shoreline use by red phalaropes is extensive, with concentrations exceeding 500 

per km of gravel beach reported on the Barrow spit and in the Simpson Lagoon area (USGS as 

cited in MMS, 2003). Sabine’s gull occurs mainly from the Deadhorse area west. 

The most abundant seabird species in the northern Bering Sea are least auklet, crested auklet, 

common murre, thick-billed murre, parakeet auklet, and black-legged kittiwake. The majority of 

the least auklet (79% eastern Bering Sea population) and crested auklet (62% eastern Bering Sea 

population) populations are concentrated on a few breeding colonies primarily on St. Lawrence 

and Little Diomede Islands. The parakeet auklet is widely distributed with small colonies 

located along the coast of Norton Sound and larger colonies present on the offshore islands. The 

common and thick-billed murres are widely distributed with breeding populations on both the 

offshore islands and along the coast of Norton Sound. Thick-billed murres generally concentrate 

on offshore islands and shelf break areas, while common murres are found more in coastal areas. 

Black-legged kittiwakes are also widely distributed with substantial mainland, coastal and 

offshore island populations. 

Most shorebirds and other waterfowl concentrate in snow-free coastal or inland areas until nest 

sites are available. Large numbers of brant and goose species often occur on lakes between 

Teshekpuk and the coast. Scattered colonies of brant occur through northwest Alaska, 

particularly from Smith Bay west to the Chukchi coast, and low numbers southward to 

Kasegaluk Lagoon (MMS, 2003). The Yukon-Kuskokwim River Delta has the greatest nesting 

concentrations of waterfowl and shorbirds in the Norton Basin with other important nesting, 

feeding, and staging areas occurring along the coast of the Seward Peninsula and St. Lawrence 

Island. 
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The greatest nesting concentration of geese in North America occurs on the Clarence Rhode 

Wildlife Range (MMS, 1982). Concentrations of Canada geese occur in the Teshekpuk Lake 

area and at lower density in the Prudhoe Bay region. Numbers of brants occupying the seacoast 

areas during the molt period vary considerably, from low thousands to tens of thousands of 

individuals, in part depending on greater or lesser nest success by the various species (MMS, 

2003). Eiders and oldsquaw are common migrants along the coast of the Arctic National 

Wildlife Refuge, although oldsquaws are widespread in northern Alaska. Large numbers of 

oldsquaws molt in Beaufort Sea lagoons and bays beginning in mid-July (MMS, 2003). 

Locations of major concentrations of molting oldsquaws include south shoreline and lagoon 

habitats near Thetis, Spy, Long, Jones, Arey, McClure, Pingok, Leavitt, Cottle, Egg, Pole, and 

Flaxman islands. Most birds are located along barrier islands or in lagoons rather than seaward 

from lagoons or along mainland shores (Flint et al. as cited in MMS, 2003). To a considerable 

extent, molting and staging individuals remain in the same area of a particular lagoon during 

their stay in the Beaufort region (Flint et al. as cited in MMS, 2003). Males, nonbreeders, and 

failed breeders are joined later by females with young. 

Males and nonbreeding or failed breeding female common eiders migrate to coastal molting 

areas in Chukchi Sea lagoons and bays beginning in late June and early July (Johnson & Herter 

as cited in MMS, 2003). Some females with young may molt in local coastal lagoons (MMS, 

2003) before moving south to wintering areas beginning in late August and continuing into early 

November. Male king eiders undertake a molt migration to the Chukchi Sea and Bering Sea 

areas from early July through August, although some molt in the Beaufort Sea (MMS, 2003). 

Young leave the breeding areas in September and October. 

Shorebirds are numerically dominant in most coastal plain bird communities occurring across 

northern Alaska (including the Arctic National Wildlife Refuge) and Canada (including Kendall 

Island Bird Sanctuary). Along the Beaufort coastline, nonincubating members of shorebird pairs 

concentrate in coastal habitats as early as mid-June. In late June to early July, several species 

move to habitats surrounding small coastal lagoons and nearby brackish pools. In late July and 

early August, adults relieved of parental duties flock in shoreline areas prior to migration. Most 

shorebirds have departed the area by mid-September. 

4.6.2. Growth and Population 

Aerial surveys over the Arctic Coastal Plain have shown that most waterfowl and other waterbird 

species have exhibited nonsignificant population trends since 1986 or 1992 (MMS, 2003), 

although there is conflicting evidence for some species. Pacific loons, glaucous gulls, northern 

pintails, greater scaup, whitewinged scoters, brant, snow geese, and tundra swans have exhibited 

overall non-significant increasing trends since 1992, while yellow-billed loons, Canada goose, 

and snowy owls show decreases (MMS, 2003); greater white-fronted goose and arctic tern 

increased significantly. Although the population of oldsquaw ducks on the Arctic coastal plain 

of Alaska has remained relatively stable, populations in Northwest Canada and other regions in 

Alaska have declined 75 percent. 
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Up to 7,500 snow geese nest on the Kendall Island Bird Sanctuary on the Mackenzie River delta. 

Snow geese nesting pairs have increased from about 100 nesting pairs in 1998 to more than 800 

pairs in 2002 (MMS, 2003). 

Recent Fish and Wildlife Service estimates of oldsquaws occupying the central Beaufort Sea 

area during surveys up to 60 kilometers offshore ranged from 20,994 in June/July to 37,792 in 

August, with densities ranging from 58.1-73.8 birds per square kilometer (MMS, 2003). 

Numbers of king eider were 19,842 (June/July) and 6,698 (August), with densities from 3.6 

(June/July) to 10.0 (August) birds/km2

; common eider numbers were 3,300 (June/July) and 1,477 

(August), with densities from 4.6 (June/July) to 56.4 (August) birds per square kilometer. 

Generally, fewer than 1,000 Pacific loons, 200 red-throated loons, and 100 yellow-billed loons 

were present in this area at very low densities. 

The highest breeding-season densities for 34 species in an area east of Prudhoe Bay ranged from 

251.7 birds per square kilometer in the second week of June to 167.0 in mid-July, and 131.7 in 

mid-August. Most abundant were Lapland longspurs and several shorebird species (Troy 

Ecological Research Assocs. as cited in MMS, 2003). 

Norton Sound has a relatively small seabird population with the largest concentration in the Bluff 

Cliffs area east of Cape Nome. Large populations of common murre are found in this area and 

on Sledge Island. The larges populations of black-legged kittiwakes occur on St. Lawrence and 

Little Diomede Islands with sizable populations on King Island, Bluff Cliffs, Sledge Island, and 

Cape Denbigh (MMS, 1982). 

About 11.6 million waterfowl, including approximately 30 percent of North America’s goose 

population, nest in the Bering Sea region (King & Dau as cited in MMS, 1982). The highest 

total densities of all waterfowl species (400 nests per square kilometer) occur along the vegetated 

intertidal zone (King & Dau as cited in MMS, 1982). Twenty-two species of waterfowl occur on 

the St. Lawrence Island; at least twelve breeding species (about 9,000 ducks, geese, and swans) 

nest and an additional 25,000 nonbreeding waterfowl nest, forage and molt. The open-water 

areas around St. Lawrence Island support an estimated 500,000 oldsquaw and 50,000 eiders 

during the winter (Fay as cited in MMS, 1982). 

4.6.3. Environmental Factors 

The spring lead system east of Point Barrow provides a long but narrow front of open water 

which is utilized by millions of birds in their migration to nesting grounds. Nearly all of the king 

eider population of Alaska and Canada, as well as thousands of olsquaws and common eiders, 

use this lead system (Sousa as cited in ADNR, 1999). Major concentrations of birds occur in 

nearshore and coastal areas such as the Plover Islands and Barrow Spit. They also concentrate at 

Pitt Point and the Colville River delta. 

The highest nesting densities generally occur in areas of mixed wet and dry habitats, whereas 

birds often move to wetter areas for broodrearing. Islands in river deltas and barrier islands 

provide the principal nesting habitat for several waterfowl and marine bird species in the Area of 

Coverage. Shorebirds prefer wet-tundra habitats or well-drained gravelly areas for nesting, 
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whereas loons use lakes, and geese prefer deeper ponds or wet tundra near lakes. Lagoons 

formed by barrier islands, bays, and river deltas provide important broodrearing and staging 

habitat for waterfowl, particularly molting oldsquaws. Arctic peregrine falcons, bald eagles, and 

Canada geese nest primarily on bluffs. 

Flocks of nonbreeding and postbreeding adults of several shorebird species move from wet 

tundra to habitats surrounding small coastal lagoons and nearby brackish pools prior to 

migration. Adults relieved of parental duties flock in shoreline areas, and juvenile semipalmated sandpipers and red phalaropes feed along inner lagoon margins prior to migration. 

Gravel beach and other shoreline types, especially lagoon margins, are used extensively by red 

phalaropes at this time. 

Emergent and wetland vegetation such as various sedges are the primary food types for most 

waterfowl. Invertebrates in brackish and freshwater flats and ponds are the principal food 

sources for shorebirds. Phalaropes, terns, auklets, murres and kittiwakes feed on zooplankton 

(MMS, 1982, 1987a). Parakeet auklets also prey on a variety of pelagic invertebrates and 

occasional small fish. Thick-billed murres, common murres, black-legged kittiwakes, horned 

puffin, and pelagic cormorant prey on fish (sand lance, arctic cod, and prickleback) during the 

nesting season (MMS, 1982). The reproductive success of black-legged kittiwakes is greatly 

dependent on the availability of sand lance during the chick-rearing period (Drury as cited in 

MMS, 1982). Black guillemots eat all kinds of animals from the sea, including crustaceans 

(crabs and shrimp), mollusks (clams and snails), and worms. The black-crowned night heron is 

an opportunistic feeder; its diet consists mainly of fish, though it is frequently rounded out by 

other items such as leeches, earthworms, aquatic and terrestrial insects. It also eats crayfish, 

mussels, squid, amphibians, lizards, snakes, rodents, birds, eggs, carrion, plant materials, and 

garbage and refuse at landfills. 

4.6.4. Critical Areas or Habitats 

Five types of habitat particularly capable of supporting a variety of marine and coastal avifauna 

include the barrier islands, coastal lagoons, coastal saltmarshes, river deltas, and offshore areas. 

The coastal waters are primary habitat for nesting, molting, feeding, and resting activities of 

migratory marine birds. Coastal tundra and delta areas are also important nesting areas for 

waterfowl such as Pacific brants; yellow-billed, red- throated, and Pacific loons; and snow geese. 

King and common eiders, Arctic terns, glaucous gulls, and black guillemots nest on barrier 

islands (MMS, 1990, p. III-B-8). 

Major concentrations of birds occur nearshore [in waters less than 20 m (66 ft) in depth] and in 

coastal areas such as Cape Thompson, Point Hope, Cape Lisburne, Seward Peninsula, Point Lay 

and Kasegaluk Lagoon, Peard Bay, Plover Islands-Barrow Spit and Elson Lagoon, Pitt PointCape Halkett, Fish Creek Delta, Colville River Delta, Simpson Lagoon, the barrier islands of 

Prudhoe Bay, Canning River delta, Yukon River delta, Hulahula River delta and Barter Island, 

St. Lawrence Island, Little Diomede Island, St. Matthew Island, Beaufort Lagoon, Icy Reef, and 

Demarcation Bay. 
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The Colville, Sagavanirktok, Canning, and Hulahula river deltas, Simpson Lagoon, and the 

Arctic National Wildlife Refuge (Capes Thompson and Lisburne, the Kasegaluk Lagoon and 

Peard Bay barrier islands, Icy Cape, and Point Franklin) provide important nesting habitat for 

loons, waterfowl, and shorebirds and include foraging habitat for seabirds nesting in these 

regions. Along the coast of the Seward Peninsula, most lagoons, deltas, river mouths, and 

coastal tundra are used by waterfowl and shorebirds for feeding, stating, molting, or nesting 

during some part of the year. The greatest concentrations of waterfowl and shorebirds tend to 

occur in the Golovin Lagoon-Fish River flats area and the Moses Point lagoon and delta area 

(Kwik River and the Kwiniuk River deltas). 

A large number of seabirds, including gulls, terns, and eiders, nest on barrier islands and spits, 

especially those associated with Kasegaluk Lagoon and Peard Bay. An important seabird 

foraging area extends from Seward Peninsula to the east side of St. Lawrence Island. 

Lesser snow geese and brant nest on Howe and Duck islands in the Sagavanirktok River Delta; 

snow geese also nest on the Ikpikpuk River delta at Smith Bay (MMS, 2003) and on the Kendall 

Island Bird Sanctuary on the Mackenzie River delta. St. Lawrence Island wetland habitats 

provide a staging area for an international population of lesser snow geese and possibly the entire 

immature nonbreeding population of emperor geese during the summer. The Colville, 

Sagavanirktok and Kuparuk river deltas provide important breeding and brood-rearing habitats 

for tundra swans, black brant, snow geese, and Canada geese. Howe Island, located in the 

Sagavanirktok River delta, is the location of one of two known snow gooses nesting colonies in 

the United States and is important for black brant nesting (Sousa as cited in ADNR, 1999). The 

Plover islands, such as Cooper and Deadman Islands, are important nesting grounds for black 

guillemont. The Colville River from Umiat to Ocean Point, and Franklin and Sagwon Bluffs in 

the Sagavanirktok River drainage are primary nesting areas for the Arctic peregrine falcon. 

Common eiders, glaucous gulls, and arctic terns nest on barrier islands in the east-central 

Beaufort Sea in addition to on other islands and causeways (MMS, 2003). Terns also nest at 

high density inland across much of the Arctic Coastal Plain, and common eiders have been 

documented nesting on the mainland near Point Thomson (MMS, 2003). The Return Islands, 

Jones Islands, McClure Islands, Cross Island, and Lion Point are important for nesting common 

eider. Black guillemots nest mainly on barrier islands in the western Beaufort, particularly 

Cooper Island (Divoky, Watson, & Bartonek as cited in MMS, 2003). Yellow-billed and redthroated loons (Gotthardt as cited in MMS, 2003) nest mainly south and west of Smith Bay. 

Greater white-fronted geese are also found nesting and rearing in the major river deltas and other 

coastal plain areas (Ott as cited in ADNR, 1999). 

Shorebirds use a range of habitats from dry gravelly to wet tundra and littoral. Important feeding 

and staging grounds for shorebirds and waterfoul include Kasegaluk Lagoon, the mouth of the 

Kuk River, Peard Bay, and saltmarshes along the mainland coast. These habitats are critical to 

waterfowl that regularly pass through or near the Beaufort and Chukchi Seas during migration. 

Major concentrations of molting waterfowl occur in several areas along the Beaufort and 

Chukchi sea coasts including Simpson Lagoon, the Teshekpuk Lake Special Area, Peard Bay, 

Kasegaluk Lagoon, and Ledyard Bay from late June through August. Postmolting and 

broodrearing brant use various coastal habitats such as sloughs and tidal flats from early July 
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through August (MMS, 2003). Snow goose broodrearing occurs in Foggy Island Bay and 

surrounding river deltas (Johnson as cited in MMS, 2003). Oldsquaws molt in Simpson and 

other Beaufort lagoons and bays beginning in mid-July (MMS, 2003). Ledyard Bay serves as an 

important staging and molting area for eiders. It is perhaps the most important feeding habitat in 

the Chukchi Sea region for eiders and many other species as well (Truett, 1984b). 

4.6.5. Effects Analysis 

Seasonal distribution of birds in the region determines their vulnerability to potentially adverse 

factors associated to a large extent with oil and gas exploration. Discharges from drilling 

operations during exploration typically disperse rapidly in the surrounding water, although some 

may be deposited on the bottom near drill sites. Because bottom-feeding sea ducks and 

guillemots occur in dispersed flocks, relatively few are expected to occur in or rely specifically 

on prey potentially affected or buried at the projected drill sites under this general permit. 

Additionally, drill structures are likely to be quite dispersed (MMS, 2003). Thus, discharges are 

not likely to cause significant effects either through direct contact with birds or by affecting prey 

availability as a result of the authorized discharges. In addition, there is likely sufficient time 

between discharges at individual sites for regional bird populations to recover from the minor 

effects that may result at each site. 

4.7. THREATENED AND ENDANGERED SPECIES 

The Endangered Species Act (ESA) requires federal agencies to consult with the U. S. Fish and 

Wildlife Service (USFWS) and the National Marine Fisheries Service (NOAA Fisheries) if the 

federal agency’s actions could beneficially or adversely affect any threatened and endangered 

species or their critical habitat. In this case, the federal agency is the USEPA, and the 

discretionary action is the reissuance of the NPDES permit. The action evaluated in this 

evaluation could affect species under the jurisdiction of both the USFWS and NOAA Fisheries. 

This evaluation identifies the endangered, threatened, and proposed species and critical habitat in 

the project area and assesses potential effects to these species that may result from the discharge 

authorized in the proposed final NPDES permit. 

The federal action under discussion in this document is the discharge of the waste streams listed 

in the general NPDES permits to the Beaufort and Chukchi Seas, and Hope and Norton Basins. 

The primary waste streams considered in this evaluation are drilling muds and cuttings, which 

are of concern due to the large volumes discharged and the potentially toxic components of 

drilling muds (e.g., metals). Other minor pollutant sources which are potentially of concern and 

were considered in this evaluation are: deck drainage, sanitary waste, domestic waste, and test 

fluids. A more complete discussion of these waste streams can be found in Section 2.0. 

Additional permitted waste streams were not considered in this evaluation because the volumes 

discharged are very small relative to the primary waste streams. 

There are three avian species, six cetacean species, and one pinnipeds species that live or spend a 

significant portion of their lives in the Area of Coverage. A summary of these species status is 

provided in Table 4-6. Table 4-7 indicates which species have critical habitat designations. The 
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remaining sections of this chapter will discuss the abundance, distribution, diet, critical habitat, 

and effects for listed species occurring in the Area of Coverage. 

4.7.1. Short-tailed Albatross 

The short-tailed albatross is listed by the USFWS as Endangered under the ESA throughout its 

range. 

4.7.1.1. Abundance and Distribution 

The albatross is a pelagic, or open-ocean, species that live from forty to sixty years. They can 

stay out at sea for as long as five years before returning to the same island on which they were 

born. Historically, the short-tailed albatross bred on a number of Japanese islands, and its range 

extended to most of the north Pacific Ocean including the Bering Sea. In the 19th century, the 

short-tailed albatross was common in the north Pacific. However, its numbers were reduced 

from more than a million birds to as few as 40 or 50 in 1940. Since that time, a slow recovery 

has brought the number of short-tailed albatross to about 1200 birds and the numbers are 

increasing (USFWS, 2001). All of the remaining birds breed on just one small island in Japan. 

The short-tailed albatross is only within the Area of Coverage to feed. 

4.7.1.2. Diet 

The short-tailed albatross eats flying fish eggs, crustaceans, shrimp, and squid. It usually feeds in 

the early morning and at twilight. 

4.7.1.3. Critical Areas or Habitats 

The short-tailed albatross lives on the open ocean waters and islands. Critical habitat has not 

been established for this species within the Area of Coverage. 

4.7.1.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. Events serious enough to 
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cause a decline in population abundance, with respect to permitted discharges, include the 

following: 

• Discharged muds and cuttings were ingested directly; 

• Consumption of prey contaminated by drilling muds in numbers sufficient to cause 

lethality or a decline in reproductive fitness; and 

• Decline in prey populations due to toxic effects of discharged muds and cuttings. 

Seasonal distribution of the spectacled eiders determines their vulnerability to potentially adverse 

factors associated with oil and gas exploration. Discharges from drilling operations during 

exploration typically disperse rapidly in the surrounding water, although some may be deposited 

on the bottom near drill sites. Because it is unlikely that exploration operations will occur in the 

Area of Coverage where the short-tailed albatross is found, it is unlikely that there will be any 

affects, directly or indirectly from prey. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the short-tailed albatross in the vicinity of the discharge. 

4.7.2. Spectacled Eider 

Spectacled eiders are listed by the USFWS as threatened under ESA throughout its range in the 

United States and Russia. 

4.7.2.1. Abundance and Distribution 

Spectacled eiders are diving ducks that spend most of the year in marine waters. Historically, 

spectacled eiders nested in the spring along much of the coast of Alaska, from the Nushagak 

Peninsula in the southwest, north to Barrow, and east nearly to the Canadian border. They also 

nested along much of the arctic coast of Russia. Today, two primary nesting grounds remain in 

Alaska; the central coast of the Yukon-Kuskokwim Delta, and the arctic coastal plain. A few 

pairs nest on St. Lawrence Island as well. 

Between the 1970’s and 1990’s, the breeding population on the Yukon-Kuskokwim Delta 

declined by over 96 percent, and only about 4,000 pairs nest there today. An estimated 7,371 

spectacled eiders (about 2 percent of the world population) seasonally occupy the arctic coastal 

plain (MMS, 2003) each summer. Breeding densities decrease from west to east (MMS, 2002). 

Population trends for spectacled eider on the arctic coastal plain are unclear, and survey data may 

reflect timing of surveys rather than actual densities (MMS, 2002). 

Important late summer and fall molting areas in Alaska have been identified in eastern Norton 

Sound and Ledyard Bay. As many as 4,000 molting individuals have been observed at one time 

(MMS, 2002). Molting flocks gather in relatively shallow coastal water, usually less than 36 m 

(120 ft) deep. Males leave the breeding grounds as incubation begins, usually around mid-June, 

and begin a molt migration, stopping in bays and lagoons to molt and stage for fall migration. 
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Females whose nests failed leave the nesting area to molt at sea by mid-August. Breeding 

females and their young remain on the nesting grounds until early September. While moving 

between nesting and molting areas, spectacled eiders travel along the coast up to 50 km (31 mi) 

offshore. 

Wintering flocks of spectacled eiders, possibly the entire population, have been observed in the 

Bering Sea between St. Lawrence and St. Matthew islands. Winter surveys in the Bering Sea, 

which includes non-breeding birds, indicate a worldwide population of about 360,000 birds 

(USFWS, 2001). During the winter months, they move far offshore to waters up to 65 m (213 ft) 

deep, where they sometimes gather in dense flocks in openings of nearly continuous sea ice. 

4.7.2.2. Diet 

Spectacled eiders feed on bottom-dwelling molluscs and crustaceans in marine waters and 

aquatic insects, crustaceans, and vegetation while nesting. 

4.7.2.3. Critical Areas or Habitats 

The USFWS has designated critical habitat (molting areas) for spectacled eider, which includes 

four areas: the Yukon-Kuskokwim delta and adjacent marine waters, Norton Sound, Ledyard 

Bay, and Bering Sea between St. Lawrence and St. Matthew Islands. Spectacled eiders nest in 

wetland habitats. Ponds with emergent vegetation appear to be important brood-rearing habitat 

for spectacled eiders (MMS, 2002). Important molting and staging areas include Harrison Bay, 

Peard Bay, Kasegaluk Lagoon, Ledyard Bay, and eastern Norton Sound (MMS 2002). 

4.7.2.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. Events serious enough to 

cause a decline in population abundance, with respect to permitted discharges, include the 

following: 
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• Discharged muds and cuttings were ingested directly; 

• Consumption of prey contaminated by drilling muds in numbers sufficient to cause 

lethality or a decline in reproductive fitness; and 

• Decline in prey populations due to toxic effects of discharged muds and cuttings. 

Seasonal distribution of the spectacled eiders determines their vulnerability to potentially adverse 

factors associated with oil and gas exploration. Discharges from drilling operations during 

exploration typically disperse rapidly in the surrounding water, although some may be deposited 

on the bottom near drill sites. Because the little available survey data from the Beaufort Sea area 

suggest that eiders apparently occur in low numbers and as dispersed flocks after breeding, 

although flocks may occur more frequently in some local area such as Harrison Bay, relatively 

few individuals are expected to occur in most local drill-site areas or rely specifically on prey 

affected or buried in such areas. Additionally, drilling structures are expected to be quite 

dispersed throughout the area of coverage (MMS, 2003). Thus, discharges are not likely to cause 

significant effects either through direct contact with birds or by affecting prey availability as a 

result of the discharges authorized by the general permit. The minor effects that may result from 

individual dischargers are not likely to substantially elevate the current nonsignificant rate of 

decline. 

No direct impact from the discharge of exploratory oil and gas drilling muds and cuttings are 

expected on the spectacled eiders. The eiders may be indirectly affected from impacts of the 

discharge/effluent to their food supply, primarily mollusks and crustaceans. Any adverse impact 

on the prey species of either eider species would be negligible because most exploratory drilling 

sites would be in waters too shallow for allowable discharges of drilling muds and cuttings. 

Feeding habitats for the endangered or threatened bird species are probably not found at 

permanent locations. Also, feeding by these bird species typically occurs close to shore, in water 

depths where discharges are typically restricted. Available information suggests that permitted 

discharges from oil and gas drilling and other associated activities are unlikely to destroy or 

adversely modify habitats critical to either eider species. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the spectacled eider and is not likely to adversely modify their critical 

habitat in the vicinity of the discharge. 

4.7.3. Steller’s Eider 

The Alaskan breeding population of Steller’s eiders is listed by the USFWS as threatened under 

the ESA. 
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4.7.3.1. Abundance and Distribution 

Steller’s eiders are diving ducks that nest in the terrestrial environment, but spend most of the 

year in shallow, near-shore marine waters. They breed in northern Russia and Alaska. The 

Alaskan breeding population nests primarily on the Arctic Coastal Plain (northern population), 

although a very small subpopulation remains on the Yukon-Kuskokwim Delta (western 

population). Historically, the northern population occurred from Wainwright east to near the 

Alaska-Canada border and the western population occurred on the Yukon-Kuskokwim Delta and 

at other western Alaska sites, including the Seward Peninsula, St. Lawrence Island, and possibly 

the eastern Aleutian Islands and Alaska Peninsula.. The historical abundance and distribution of 

the western population is not known, but by the 1960s or 70s, the species had become extremely 

rare on the Yukon-Kuskokwim Delta. No nests were found in this area from 1975-1993 and 

seven nests were found from 1994-2002. Evidence of nesting Steller’s eiders has not been 

reported on the Seward Peninsula since the late 1800’s or on St. Lawrence Island since 1954. 

Steller’s eiders in Alaska nest on tundra adjacent to small ponds or within drained lake basins, 

generally near the coast but ranging at least as far as 90 km (56 mi) inland. Current primary 

nesting range in Alaska consists of a portion of the central arctic coastal plain between 

Wainwright and Prudhoe Bay, primarily near Barrow. Steller’s eiders have been seen mainly in 

the northern half of the National Petroleum Reserve-Alaska and on private land near Barrow. 

The majority of the sightings in the last decade have occurred east of Point Lay, west of Nuiqsut 

on the Colville River, and within 90 km (56 mi) of the coast. While they occur over a vast area, 

the density is much greater near Barrow, which is the core of the Steller’s eider’s breeding range. 

The number of pairs nesting on Alaska’s arctic coastal plain is very roughly estimated at 1,000. 

Approximately 4,000 pairs of Steller’s eiders may have nested on the Yukon-Kuskokwim Delta 

prior to the 1960’s. Recently, only a few pairs have been found breeding in this area (MMS, 

2002). 

After breeding, Steller’s eiders move to marine waters where they undergo a complete molt. 

During the autumn molt, winter, and spring migration, the Alaska-breeding population 

intermixes with the larger Russian-Pacific population in the marine waters of southwest Alaska. 

Concentrations of molting Steller’s eiders have been observed near Bering Sea islands, and in 

bays and estuaries from southwest Alaska to the northern shore of the Alaska Peninsula. Kessel 

(as cited in MMS, 2002) noted that eiders typically move through the Bering Strait between midMay and early June. Steller’s eiders gather in staging areas before beginning their spring 

migration. Biologists estimate that the world population of Steller’s eiders is around 220,000 

birds, the majority of which nest in Russia. Overall, the worldwide population of Steller’s eiders 

may have decreased by as much as 50% over the last 30 years. 
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4.7.3.2. Diet 

The Steller’s eider diet includes crustaceans and mollusks. While nesting, they feed on aquatic 

insects and plants in freshwater ponds and streams 

4.7.3.3. Critical Areas or Habitats 

The USFWS designated critical habitat for Steller’s eiders, which includes nesting areas on the 

Yukon-Kuskokwim delta and areas on the north side of the Alaska Peninsula (Izembek Lagoon, 

Nelson Lagoon, and Seal Islands) where Steller’s eiders molt, winter, and stage during spring 

migration. The region surrounding Barrow has been identified as being important to the survival 

and recovery of the Alaska-breeding population. 

4.7.3.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. Events serious enough to 

cause a decline in population abundance, with respect to permitted discharges, include the 

following: 

• Discharged muds and cuttings were ingested directly; 

• Consumption of prey contaminated by drilling muds in numbers sufficient to cause 

lethality or a decline in reproductive fitness; and 

• Decline in prey populations due to toxic effects of discharged muds and cuttings. 

Seasonal distribution of the Steller’s eiders determines their vulnerability to potentially adverse 

factors associated with oil and gas exploration. Discharges from drilling operations during 

exploration typically disperse rapidly in the surrounding water, although some may be deposited 

on the bottom near drill sites. Because the little available survey data from the Beaufort Sea area 

suggest that eiders apparently occur in low numbers and as dispersed flocks after breeding, 

although flocks may occur more frequently in some local area such as Harrison Bay, relatively 

few individuals are expected to occur in most local drill-site areas or rely specifically on prey 

affected or buried in such areas. Additionally, drilling structures are expected to be quite 

dispersed throughout the area of coverage (MMS, 2003). Thus, discharges are not likely to cause 

significant effects either through direct contact with birds or by affecting prey availability as a 

result of the discharges authorized by the general permit. The minor effects that may result from 
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individual dischargers are not likely to substantially elevate the current nonsignificant rate of 

decline. 

No direct impact from the discharge of exploratory oil and gas drilling muds and cuttings are 

expected on the Steller’s eiders. The eiders may be indirectly affected from impacts of the 

discharge/effluent to their food supply, primarily mollusks and crustaceans. Any adverse impact 

on the prey species of either eider species would be negligible because most exploratory drilling 

sites would be in waters too shallow for allowable discharges of drilling muds and cuttings. 

Feeding habitats for the endangered or-threatened bird species are probably not found at 

permanent locations. Also, feeding by these bird species typically occurs close to shore, in water 

depths where discharges are typically restricted. Available information suggests that permitted 

discharges from oil and gas drilling and other associated activities are unlikely to destroy or 

adversely modify habitats critical to either eider species. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the Steller’s eider and is not likely to adversely modify their critical habitat 

in the vicinity of the discharge. 

4.7.4. Blue Whale (North Pacific Stock) 

The North Pacific stock of blue whales is listed by the NOAA Fisheries as endangered under 

ESA throughout its range. 

4.7.4.1. Abundance and Distribution 

The blue whale is largest baleen whale. The lifespan of a blue whale is estimated to be 80 years. 

The blue whale population is estimated between 1,300 and 2,000; there are currently no 

estimates of the North Pacific stock of blue whale. The North Pacific stock has been found in 

the Bering Sea, although rarely. Blue whales migrate to tropical-to-temperate waters during 

winter months to mate and give birth to calves. They can feed throughout their range, in polar, 

temperate, or even tropical waters. This species is rarely seen near the coast, except in polar 

regions when it follows the retreating ice-edge. This in turn can cause entrapment by ice as the 

weather changes. Blue whales are usually found either in pairs (as in mother and calf) or as a 

solitary animal. However, this species has been found to congregate on the feeding grounds, and 

do not, as a rule, dive deeply (maximum 200 m). 

4.7.4.2. Diet 

The blue whale feeds on zooplankton (euphausiids or krill). Since euphausiids are also the 

primary food for other whales in the Area of Coverage, the blue whale is in direct competition 

with these species for food. 
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4.7.4.3. Critical Areas or Habitats 

Critical habitat has not been established for this species within the Area of Coverage. 

4.7.4.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. 

The blue whales are seasonal feeders, obtaining their food primarily on their summer range. The 

consumption of contaminated prey items could result in the bioaccumulation of metals (i.e., 

cadmium or organic forms of mercury) by whales, potentially resulting in toxicity. The degree 

to which food supplies of these whales would be impacted would depend on the area affected 

and the concentrations of these metals in the discharge. Based on the limited areal extent of 

impacts in relation to the total area containing potential prey, the episodic nature of the 

discharges, the low concentrations of metals in the discharge, and the mobility of whales and 

their prey, the discharge is not likely to adversely affect the listed whale species. 

It is likely that whales will avoid the activity occurring in the drilling areas and thus avoid 

contact with prey residing within the more concentrated portions of the plume during discharge. 

The majority of bowhead whales exposed to recordings of drillship noise in the Area of 

Coverage oriented away from the noise source. Noise levels eliciting an avoidance response 

were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richardson et al., 1990, p. 156). 

No specific habitats critical to the existence of the endangered whale species have been 

identified. Calving for the listed whales occurs outside the area under consideration in this 

document. Due to the absence of identified critical habitats in the area proposed for exploratory 

oil and gas drilling, the potential for adverse impacts to habitat can not be determined 

definitively. However, it is unlikely that discharges from the limited exploratory activities 

proposed would adversely impact these feeding habitats. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the blue whale in the vicinity of the discharge. 

4.7.5. Bowhead Whale (Western Arctic Stock) 

The Western Arctic stock of bowhead whales is listed by the NOAA Fisheries as endangered 

under ESA throughout its range. 
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4.7.5.1. Abundance and Distribution 

Bowhead whales are distributed in seasonally ice-covered waters of the arctic and near-arctic, 

typically between 54° N and 75°N latitude in the western Arctic Basin. The Bering Sea stock 

(also called the Western Arctic stock) is the largest remnant population and the only stock that is 

found within U. S. waters. Prior to commercial fishing in the Bering Sea (mid-19th century), it is 

estimated that the Western Arctic Stock population was between 10,400 and 23,000. The 

population dropped to less than 3,000 at the end of commercial whaling. The Western Arctic 

stock has increased at a rate of 3.1% from 1978 to 1993, during which time abundance increased 

from approximately 5,000 to 8,000 whales (Raftery et al. as cited in NOAA, 2002a). In 1993, 

counts at Point Barrow resulted in an estimated population of 8,000 (Zeh et al. as cited in 

NOAA, 2002a). Acoustic data from 1993 has resulted in an estimate of 8,200 animals and is 

considered the best available abundance estimate for the Western Arctic stock (IWC; Zeh et al. 

as cited in NOAA, 2002a). 

The majority of the Western Arctic stock migrates annually from wintering areas (November to 

March) in the northern Bering Sea through the Chukchi Sea in the spring (March through June) 

and into the Canadian Beaufort Sea, where they spend much of the summer (mid-May through 

September) before returning again in the fall (September through November) (Braham et al.; 

Moore & Reeves as cited in NOAA, 2002a). The bowhead spring migration follows fractures in 

the sea ice around the coast of Alaska, generally in the shear zone. As the whales travel east past 

Point Barrow, their migration is somewhat funneled between shore and the polar pack ice 

(Krogman as cited in NOAA, 2002a). Most of the year, bowhead whales are closely associated 

with sea ice (Moore & DeMaster as cited in NOAA, 2002a); only during the summer is this 

population in relatively ice-free waters in the southern Beaufort Sea (Richardson et al. as cited in 

NOAA, 2002a). Sightings of bowhead whales do occur in the summer near Barrow (Moore; 

Moore & DeMaster as cited in NOAA, 2002a). Some bowheads are found in the Chukchi and 

Bering Seas in summer; these are thought to be part of the expanding Western Arctic stock. Fall 

surveys show that the bowhead whales are found close inshore east of Barter Island and from 

Cape Halkett to Point Barrow generally in water depths less than 50 m (MMS, 2002). 

4.7.5.2. Diet 

Food items of bowheads include euphausiids, mysids, copepods, and amphipods. Since 

euphausiids are also the primary food for other whales in the Area of Coverage, the bowhead 

whale is in direct competition with these species for food. 

4.7.5.3. Critical Areas or Habitats 

No critical habitat for bowheads has yet been defined in Alaskan waters; however, NOAA 

Fisheries is currently reviewing a petition to designate critical habitat. Bowheads are most 

sensitive during their spring migration when calves are present and their movements are 
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restricted to open leads in the ice. Feeding concentrations occur in areas east of Barter Island 

(MMS, 2003) and certain areas near Barrow are important feeding grounds. 

4.7.5.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. 

The bowhead whales are seasonal feeders, obtaining their food primarily on their summer range. 

The consumption of contaminated prey items could result in the bioaccumulation of metals (i.e., 

cadmium or organic forms of mercury) by whales, potentially resulting in toxicity. The degree 

to which food supplies of these whales would be impacted would depend on the area affected 

and the concentrations of these metals in the discharge. Based on the limited areal extent of 

impacts in relation to the total area containing potential prey, the episodic nature of the 

discharges, the low concentrations of metals in the discharge, and the mobility of whales and 

their prey, the discharge is not likely to adversely affect the listed whale species. 

It is likely that whales will avoid the activity occurring in the drilling areas and thus avoid 

contact with prey residing within the more concentrated portions of the plume during discharge. 

The majority of bowhead whales exposed to recordings of drillship noise in the Area of 

Coverage oriented away from the noise source. Noise levels eliciting an avoidance response 

were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richardson et al., 1990, p. 156). 

No specific habitats critical to the existence of the endangered whale species have been 

identified. Calving for the listed whales occurs outside the area under consideration in this 

document. Due to the absence of identified critical habitats in the area proposed for exploratory 

oil and gas drilling, the potential for adverse impacts to habitat can not be determined 

definitively. However, it is unlikely that discharges from the limited exploratory activities 

proposed would adversely impact these feeding habitats. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the bowhead whale in the vicinity of the discharge. 

4.7.6. Fin Whale (Northeast Pacific Stock) 

The Northeast Pacific stock of fin whales is listed by the NOAA Fisheries as endangered under 

ESA throughout its range. 
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4.7.6.1. Abundance and Distribution 

Fin whales range from subtropical (Hawaii and North American Pacific coast) to arctic waters 

and are usually found in areas of dense productivity. Their summer distribution extends from 

central Baja California into the Chukchi Sea, while their winter range is restricted to the waters 

off the Pacific coast of North America. The Northeast Pacific stock, one of three stocks 

identified for the fin whale, is the only one identified for the Area of Coverage. Reliable 

estimates of current and historical abundance for the Northeast Pacific fin whale stock are not 

currently available. The North Pacific fin whale population was estimated at 16,600 individuals 

in 1991 (MMS, 2002). Ranges of population estimates based on population modeling for the 

entire North Pacific prior to exploitation are 42,000 to 45,000 and in the early 1970s are 14,620 

to 18,630 (Ohsumi & Wada as cited in NOAA, 2003a). Fin whale abundance estimates for the 

Northeast Pacific stock from 1999 and 2000 surveys were nearly five times higher in the centraleastern Bering Sea (est. pop. 3,368) than in the southeastern Bering Sea (est. pop. 683) (Moore et 

al. as cited in NOAA, 2003a), and most sightings in the central-eastern Bering Sea occurred in a 

zone of particularly high productivity along the shelf break (Moore et al. as cited in NOAA, 

2003a). Reliable information on trends in abundance for the Northeast Pacific stock of fin 

whales is not currently available. There is no indication whether recovery of this stock has or is 

taking place (Braham; Perry et al. as cited in NOAA, 2003a). 

Some fin whales in the Northeast Pacific stock feed in the Gulf of Alaska, while others migrate 

farther north to feed throughout the Bering and Chukchi Seas from June through October. From 

September through November, most migrate southward to California; however, a few animals 

may remain in the Navarin Basin (MMS, 2002). Fin whales usually breed and calve in the 

warmer waters of their winter range. Breeding can occur year-round, but the peak occurs 

between November and February (MMS, 2002).Northward migration begins in spring with 

migrating whales entering the Gulf of Alaska from early April to June (MMS, 2002). 

4.7.6.2. Diet 

Fin whales are opportunistic feeders, taking euphausiids, copepods, fishes, and squids. Since 

euphausiids are also the primary food for other whales in the Area of Coverage, the fin whale is 

in direct competition with these species for food. 

4.7.6.3. Critical Areas or Habitats 

 Critical habitat has not been established for this species within the Area of Coverage. 
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4.7.6.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. 

The fin whales are seasonal feeders, obtaining their food primarily on their summer range. The 

consumption of contaminated prey items could result in the bioaccumulation of metals (i.e., 

cadmium or organic forms of mercury) by whales, potentially resulting in toxicity. The degree 

to which food supplies of these whales would be impacted would depend on the area affected 

and the concentrations of these metals in the discharge. Based on the limited areal extent of 

impacts in relation to the total area containing potential prey, the episodic nature of the 

discharges, the low concentrations of metals in the discharge, and the mobility of whales and 

their prey, the discharge is not likely to adversely affect the listed whale species. 

It is likely that whales will avoid the activity occurring in the drilling areas and thus avoid 

contact with prey residing within the more concentrated portions of the plume during discharge. 

The majority of bowhead whales exposed to recordings of drillship noise in the Area of 

Coverage oriented away from the noise source. Noise levels eliciting an avoidance response 

were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richardson et al., 1990, p. 156). 

No specific habitats critical to the existence of the endangered whale species have been 

identified. Calving for the listed whales occurs outside the area under consideration in this 

document. Due to the absence of identified critical habitats in the area proposed for exploratory 

oil and gas drilling, the potential for adverse impacts to habitat can not be determined 

definitively. However, it is unlikely that discharges from the limited exploratory activities 

proposed would adversely impact these feeding habitats. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the fin whale in the vicinity of the discharge. 

4.7.7. Humpback Whale (Western and Central Stocks) 

The Western and Central stocks of humpback whales are listed by the NOAA Fisheries as 

endangered under ESA throughout their range. 
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4.7.7.1. Abundance and Distribution 

Humpbacks are widely distributed in all oceans, though it is less common in Arctic waters. Of 

the four currently recognized stocks, only two (central North Pacific stock and western North 

Pacific stock) are present in the Area of Coverage. The general range of the humpback whale is 

from tropical wintering grounds near islands and continental coasts to open-ocean temperate and 

sub-polar summering habitats. The range of the central North Pacific stock is from the Hawaiian 

Islands to northern British Columbia/Southeast Alaska and Prince William Sound west to 

Kodiak. The range of the western North Pacific stock is from Japan to waters west of the Kodiak 

Archipelago (the Bering Sea and Aleutian Islands). 

Prior to commercial whaling, the worldwide population of humpback whales is though to have 

been in excess of 125,000; currently it is estimated that the U. S. population of humpbacks is less 

than 7,000 whales. The current total estimated abundance for the central North Pacific stock is 

4,005. The sum of the available estimates of this stock for the known feeding areas is 2,036 (149 

in Prince William Sound; 651 in Kodiak; 961 in Southeast Alaska; and 275 in British Columbia). 

At least some portions of the stock have increased in abundance between the early 1980s and 

2000, although recent trends indicate that the stock is approaching its carrying capacity. The 

population size of the western North Pacific stock is estimated to be 394. There are no reliable 

estimates for the abundance of this stock at feeding areas because the specific feeding areas are 

largely unknown. Reliable information on trends in abundance is also currently unavailable. 

Humpback whales are seasonal migrants and are generally considered to inhabit waters over 

continental shelves, along their edges and around some oceanic islands. During winter (the 

breeding season), most humpbacks are found in temperate and tropical waters. It is thought that 

little feeding occurs on the wintering grounds. Although humpbacks mate and give birth in 

wintering areas, reproductive events may also take place during migration. There are no reported 

features that characterize the migration routes of all populations of humpbacks. Some whales 

migrate across the open ocean (from Hawaiian waters to those of Southeastern Alaska), while 

others migrate through coastal waters (from Mexico to Southeastern Alaska). In summer (the 

feeding season), most humpbacks migrate considerable distances to waters of high biological 

productivity, usually in higher latitudes. Summer ranges are often relatively close to shore 

including major coastal embayments and channels. However, humpbacks may also summer 

offshore, as in the Gulf of Alaska. 

4.7.7.2. Diet 

The humpback whale diet consists of small schooling fishes (including herring, sand lance, 

capelin, mackerel, small Pollock, and haddock) and large zooplankton, mainly krill. Since 

euphausiids are also the primary food for other whales in the Area of Coverage, the humpback 

whale is in direct competition with these species for food. 
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4.7.7.3. Critical Areas or Habitats 

Critical habitat has not been established for this species within the Area of Coverage. Feeding 

grounds are critical to the humpback’s survival. 

4.7.7.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. 

The humpback whales are seasonal feeders, obtaining their food primarily on their summer 

range. The consumption of contaminated prey items could result in the bioaccumulation of 

metals (i.e., cadmium or organic forms of mercury) by whales, potentially resulting in toxicity. 

The degree to which food supplies of these whales would be impacted would depend on the area 

affected and the concentrations of these metals in the discharge. Based on the limited areal extent 

of impacts in relation to the total area containing potential prey, the episodic nature of the 

discharges, the low concentrations of metals in the discharge, and the mobility of whales and 

their prey, the discharge is not likely to adversely affect the listed whale species. 

It is likely that whales will avoid the activity occurring in the drilling areas and thus avoid 

contact with prey residing within the more concentrated portions of the plume during discharge. 

The majority of bowhead whales exposed to recordings of drillship noise in the Area of 

Coverage oriented away from the noise source. Noise levels eliciting an avoidance response 

were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richardson et al., 1990, p. 156). 

No specific habitats critical to the existence of the endangered whale species have been 

identified. Calving for the listed whales occurs outside the area under consideration in this 

document. Due to the absence of identified critical habitats in the area proposed for exploratory 

oil and gas drilling, the potential for adverse impacts to habitat can not be determined 

definitively. However, it is unlikely that discharges from the limited exploratory activities 

proposed would adversely impact these feeding habitats. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the humpback whale in the vicinity of the discharge. 

4.7.8. Right Whale (North Pacific Stock) 

The North Pacific right whale is listed by the NOAA Fisheries as endangered under ESA 

throughout its range. 
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4.7.8.1. Abundance and Distribution 

Whaling records indicate that right whales in the North Pacific ranged across the entire North 

Pacific north of 35°N and occasionally as far south as 20°N (Roenbaum et al. as cited in NOAA, 

2003b). Sightings have been reported as far south as central Baja California in the eastern North 

Pacific and Hawaii in the central North Pacific, and as far north as the sub-Arctic waters of the 

Bering Sea and Sea of Okhotsk in the summer (NOAA, 2003b). 

Before right whales in the North Pacific were heavily exploited by commercial whalers, 

concentrations were found in the Gulf of Alaska, eastern Aleutian Islands, southcentral Bering 

Sea, Sea of Okhotsk, and Sea of Japan (Braham & Rice as cited in NOAA, 2003b). The preexploitation size of this stock exceeded 11,000 (NOAA, 2003b). In 1973, Wada (as cited in 

NOAA, 2003b) estimated a total population of 100-200 in the North Pacific. During 1958-82, 

there were only 32-36 sightings of right whales in the central North Pacific and Bering Sea 

(Braham as cited in NOAA, 2003b). A reliable estimate of abundance for the North Pacific right 

whale stock is currently unavailable. 

Right whales prefer coastlines and sometimes large bays, but may spend a lot of time on the open 

sea. They calve in coastal waters during the winter months. Migratory patterns of the North 

Pacific stock are unknown, although it is thought the whales spend the summer on high-latitude 

feeding grounds and migrate to more temperate waters during the winter (Braham & Rice as 

cited in NOAA, 2003b). Preliminary analysis of data from recorders indicates that right whales 

remain in the southeastern Bering Sea at least through October (NOAA, 2003b). Right whales 

have not been observed outside the localized area in the southeastern Bering Sea during surveys. 

4.7.8.2. Diet 

Right whales mostly eat small crustaceans including copepods and small shrimp-like animals 

called euphausiids. Since euphausiids are also the primary food for other whales in the Area of 

Coverage, the right whale is in direct competition with these species for food. 

4.7.8.3. Critical Areas or Habitats 

Critical habitat has not been established for this species within the Area of Coverage. 

4.7.8.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 
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discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. 

The right whales are seasonal feeders, obtaining their food primarily on their summer range. The 

consumption of contaminated prey items could result in the bioaccumulation of metals (i.e., 

cadmium or organic forms of mercury) by whales, potentially resulting in toxicity. The degree 

to which food supplies of these whales would be impacted would depend on the area affected 

and the concentrations of these metals in the discharge. Based on the limited areal extent of 

impacts in relation to the total area containing potential prey, the episodic nature of the 

discharges, the low concentrations of metals in the discharge, and the mobility of whales and 

their prey, the discharge is not likely to adversely affect the listed whale species. 

It is likely that whales will avoid the activity occurring in the drilling areas and thus avoid 

contact with prey residing within the more concentrated portions of the plume during discharge. 

The majority of bowhead whales exposed to recordings of drillship noise in the Area of 

Coverage oriented away from the noise source. Noise levels eliciting an avoidance response 

were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richardson et al., 1990, p. 156). 

No specific habitats critical to the existence of the endangered whale species have been 

identified. Calving for the listed whales occurs outside the area under consideration in this 

document. Due to the absence of identified critical habitats in the area proposed for exploratory 

oil and gas drilling, the potential for adverse impacts to habitat can not be determined 

definitively. However, it is unlikely that discharges from the limited exploratory activities 

proposed would adversely impact these feeding habitats. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the right whale in the vicinity of the discharge. 

4.7.9. Sperm Whale (North Pacific Stock) 

The North Pacific stock of humpback whales is listed by the NOAA Fisheries as endangered 

under ESA throughout its range. 

4.7.9.1. Abundance and Distribution 

The sperm whale is one of the most widely distributed of any marine mammal species, although 

the shallow continental shelf apparently bars their movement into the north-eastern Bering Sea 

and Arctic Ocean. Historic estimates for the abundance of sperm whales in the North Pacific are 

unreliable. It is estimated that the population was 1,260,000 prior to exploitation. By the 1970s, 

the population was estimated to have been reduced to 930,000 (Rice as cited in NOAA, 2003c). 

The current and historic number of sperm whale occurring within Alaska waters in unknown. 

The seasonal movement of sperm whales in the North Pacific is unclear at this time. Females 

and young sperm whales usually remain in tropical and temperate waters year-round, while 
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males are thought to move north in the summer to feed in the Gulf of Alaska, Bering Sea, and 

waters around the Aleutian Islands. In the winter, sperm whales are typically distributed south of 

40°N (Gosho et al. as cited in MMS, 2003c); however, commercial whaling data revealed a great 

deal of east-west movement between Alaska waters and the western North Pacific (Japan and the 

Bonin Islands), with little evidence of north-south movement in the eastern North Pacific. 

4.7.9.2. Diet 

The sperm whale feeds primarily on medium-sized to large-sized squids but may also feed on 

large demersal and mesopelagic sharks, skates, and fishes. 

4.7.9.3. Critical Areas or Habitats 

Critical habitat has not been established for this species within the Area of Coverage. 

4.7.9.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. 

The sperm whales are seasonal feeders, obtaining their food primarily on their summer range. 

The consumption of contaminated prey items could result in the bioaccumulation of metals (i.e., 

cadmium or organic forms of mercury) by whales, potentially resulting in toxicity. The degree 

to which food supplies of these whales would be impacted would depend on the area affected 

and the concentrations of these metals in the discharge. Based on the limited areal extent of 

impacts in relation to the total area containing potential prey, the episodic nature of the 

discharges, the low concentrations of metals in the discharge, and the mobility of whales and 

their prey, the discharge is not likely to adversely affect the listed whale species. 

It is likely that whales will avoid the activity occurring in the drilling areas and thus avoid 

contact with prey residing within the more concentrated portions of the plume during discharge. 

The majority of bowhead whales exposed to recordings of drillship noise in the Area of 

Coverage oriented away from the noise source. Noise levels eliciting an avoidance response 

were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richardson et al., 1990, p. 156). 

No specific habitats critical to the existence of the endangered whale species have been 

identified. Calving for the listed whales occurs outside the area under consideration in this 
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document. Due to the absence of identified critical habitats in the area proposed for exploratory 

oil and gas drilling, the potential for adverse impacts to habitat can not be determined 

definitively. However, it is unlikely that discharges from the limited exploratory activities 

proposed would adversely impact these feeding habitats. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the sperm whale in the vicinity of the discharge. 

4.7.10. Steller Sea Lion (Western Alaska Stock) 

The Western stock of Steller sea lion is listed by the NOAA Fisheries as endangered under ESA 

throughout its range. 

4.7.10.1. Abundance and Distribution 

The Steller sea lion is distributed around the North Pacific Ocean rim from northern Hokkaiddo, 

Japan through the Kuril Islands and Okhotsk Sea, Aleutian Islands and central Bering Sea, 

southern coast of Alaska and south to the Channel Islands, California. The population is divided 

into Western and Eastern Stock at 144° W longitude. The western stock is the species within the 

Area of Coverage. 

In 1956-60, the population of sea lions in the Gulf of Alaska and Aleutian Islands was estimated 

at 140,000 (NOAA, 2002b). The number of Steller sea lions in the western stock declined by 

75% between 1976 and 1990. In the 1990s, the decline continued for the western stock in 

Alaska. In 1998, surveys estimated a minimum abundance of 38,788 Steller sea lions in the 

western U.S. stock (NOAA, 2002b). Counts at trend sites during 2000 indicate that the number 

of sea lions in the Bering Sea/Aleutian Islands region has declined 10.2% between 1998 and 

2000. 

4.7.10.2. Diet 

Sea lions are carnivorous and feed exclusively on fish they catch themselves; their diet varying 

with whatever is abundant in the area. Because of the animal's remote and rugged habitat, and 

because collecting specimens at sea is difficult, much is unknown about its diet habits. However, 

recent scientific studies indicate that their diet consists of game fish (e.g., salmon) and bottom 

fish (e.g., skate, small sharks, squid and various species of rock fish). 
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4.7.10.3. Critical Areas or Habitats 

The NOAA Fisheries has designated critical habitat in Alaska for Stellar sea lions, which 

includes all a number of rookeries and major haulouts, including associated terrestrial, air, and 

aquatic zones. 

None of the major Steller sea lion rookeries or haulouts designated for critical habitat is within 

the Area of Coverage. 

4.7.10.4. Effects Analysis 

Endangered or threatened species may be adversely impacted by exploratory oil and gas 

operations either directly, by the discharged muds and cuttings and other permitted discharges, or 

indirectly, via impacts to their habitat and food supply (e.g., bioaccumulation of metals from 

discharge of muds and cuttings). The potential adverse effects of drilling muds and cuttings 

discharges are of primary concern due to the large volume discharged and the presence of 

potentially toxic components (e.g., metals) in the discharged muds. 

The EPA has determined that the issuance of this permit may affect but is not likely to 

adversely affect the Steller sea lion in the vicinity of the discharge. 

4.7.11. Uncertainty Evaluation 

4.7.11.1. Environmental Baseline 

The measurement of chemicals associated with the discharge from oil and gas exploration 

facilities has been sporadic at best. Most of the studies conducted were only for drilling muds 

and cuttings and located in the Gulf of Mexico. Studies for Arctic Alaska were conducted in the 

late 1970’s and early 1980’s. There is no discussion of the hydrological or hydraulic conditions 

which will affect dispersion of the constituents associated with the discharges. Sediment 

samples have not been collected as part of the investigation of chemicals associated with oil and 

gas exploration facilities in the Arctic. Thus, the data reported for sediment concentrations 

represent estimates of the contaminant load; however, there is a great deal of uncertainty 

regarding how representative these samples are of the distribution of contaminants in the Arctic 

environment. A quality assurance review of the data was not completed therefore the accuracy 

of the data are unknown. 

No specific studies of biota were done in the area. Therefore, no definitive statements can be 

made regarding the chemical contaminants in aquatic fish and any fish data cannot be directly 
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correlated with any sediment data collected in and near the vicinity of the oil and gas exploration 

facilities. 

Other sources of constituents associated with oil and gas exploration facilities include sanitary 

and domestic wastes, desalination unit wastes, boiler blowdown, test fluids, deck drainage, 

blowout preventer fluids, uncontaminated ballast and bilge water, excess cement slurry, noncontact cooling water, fire control system test water, and excess cement slurry at the sea floor. 

None of these sources is described in detail nor are they specific data associated with their 

effluent discharges or operations. Without specific data for these other sources it is difficult to 

attribute any baseline data. 

Cumulative exposures to multiple stressors from other sources were not evaluated in this permit. 

Other exposures to stressful conditions may render species more or less sensitive to the 

constituents in the oil and gas exploration discharges. They also may alter the behavior of the 

species such that they are or more or less likely to be exposed to releases from the discharges. 

The lack of knowledge regarding the likelihood of cumulative exposures increases the 

uncertainty in the effects determination. 

Uncertainty in toxic chemical levels is primarily associated with variability in fish tissue and 

sediment concentrations over space and time as well as errors in chemical analytical methods. 

When compiling concentration data the detection limit for each chemical in each sample 

introduces uncertainty in the resulting concentrations. The detection limits in the sediment data 

was sufficiently high for the treatment of non-detects to hide trends between dioxin and furan 

concentration and distance. 

4.7.11.2. Ecological Effects Determinations 

4.7.11.2.1. Parameters of concern 

Chemical descriptions are based on general information regarding the physical, chemical, and 

biological behavior of the mill effluent constituents in fresh water. Information on certain 

compounds is extremely limited due to the lack of site specific data on these particular 

constituents. 

The parameters of concern in this evaluation are those which were considered under the effluent 

guidelines or as having “reasonable potential” in the development of effluent limits for the final 

permit. Other pollutants may be present in the effluent discharge, but at concentrations that are 

well below the applicable water quality standards. 
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4.7.11.2.2. Conclusion determinations 

Confidence in the conclusions of the evaluation that uses the toxicity in relevant studies depends 

upon the quality of the available toxicity data. Ideally, to predict with the greatest accuracy 

whether an effect may be adverse, one would use toxicity data from an experiment that measures 

the type of toxicological response that is of interest, using the species of interest and the 

experimental design most easily extrapolated to the conditions of interest. However, there are no 

specific toxicity studies which are appropriate for this particular evaluation. 

A thorough review of the scientific literature was conducted to identify as many sources of 

toxicity data for these parameters as possible. In some cases, toxicity data were obtained from a 

previously compiled collection of toxicity information. In other cases, individual papers 

published in the scientific literature were reviewed. In still other cases, the toxicity data used by 

EPA to derive water quality criteria or effluent guidelines were reviewed. 

The quantity and quality of toxicity data available for permitted discharges varies widely. Most 

studies obtained toxicity data from experiments using a single chemical in a controlled exposure 

setting (such as an aquarium). 

In some cases, the study reporting the lowest concentration for a parameter did not report the 

endpoint [e.g., no observable effect concentration (NOEC), lowest observable effect 

concentration (LOEC)]. For these chemicals, the lowest endpoint reported was used and then 

other endpoints were extrapolated using safety factors (e.g., if only a LC50 was reported, then a 

safety factor would be applied to obtain an estimated LOEC and another safety factor would be 

applied to obtain an estimated NOEC). 

Extrapolation across species 

Although using surrogate toxicity data from a similar species, lifestage, or parameter increases 

the uncertainty associated with the evaluation, this approach is preferable to omitting the 

evaluation of a species or parameter with no toxicity data. 

Actual direct testing of potential toxicity has not been conducted for all chemicals and listed 

species. While some toxicity data have been collected for nearly all the parameters of concern, 

toxicity data are generally not available for every life stage of a listed species. In cases where 

little or no toxicity data are available for a parameter of concern to each lifestage of a listed 

species, toxicity data from a similar parameter, species, or lifestage was used as a surrogate. 

The surrogate species were selected as the closest related organism for which information was 

available. In judging whether other (tested) species can be used as a surrogate for listed species, 

it is important to know whether the tested species is more sensitive than, less sensitive than, or 

about equally sensitive as the listed species. In this case, “sensitivity” refers to the relative 

severity of the observed toxicity in one species as compared to the other. A highly sensitive 
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species exposed to a certain concentration of a parameter would experience more severe toxicity 

than a less sensitive species exposed to the same concentration. 

When a tested species is more sensitive or about equally sensitive to a non-tested species, the 

tested species can be considered a suitable surrogate for the non-tested species. The comparative 

sensitivity of listed species and surrogate species can be ascertained by comparing the toxicity 

observed in surrogate species to the toxicity observed in other species exposed to certain wellstudied chemicals. Dwyer et al. (1995) used this type of comparative sensitivity approach to 

estimate the potential toxicity of several chemicals to endangered and threatened fish species for 

which no toxicity data were available. Generally, the rainbow trout (Oncorhynchus mykiss) has 

been considered a suitable surrogate for coldwater fishes, and the Fathead minnow (Pimephales

promelas) has been considered a suitable surrogate for warm water fishes (Dwyer et al., 1995). 

Extrapolation across chemicals 

For some parameters with effluent limits in the proposed permit, little or no toxicity data using 

aquatic species are available. Therefore, parameter-specific toxicity data cannot be used to 

assess potential effects to listed species. For some species there is no data on specific chemicals 

nor are there data for extrapolation across chemicals or species. For avian species there are no 

data in the literature for the effects of most chemicals. A determination of likely to cause 

adverse effects was made although there are no data to support this position. The goal of this 

evaluation is to set limits which are protective of the endangered species. It was therefore 

assumed that in lieu of any data to the contrary a determination that there is a likelihood of 

adverse effects will be made when there are no toxicity data to make a site specific 

determination. 

4.7.11.2.3. Indirect effects to prey species 

The effects determination relied on the salmonids as a measure of the effect on fish prey species 

and the benthic community. The determination was simply based on the possibility of benthic 

organisms inhabiting the area adjacent to and within the 1,000 meter area of the discharge. 

Little information is presently available concerning the effects of various deposition depths on 

benthic communities. Most studies that have investigated deposition impacts on benthos have 

examined deposition of dredged materials (Hale, 1972; Kranz, 1974; Mauer et al., 1978; Oliver 

& Slattery, 1973; Saila et al., 1972; Schafer, 1972; Schulenberger, 1970; Wilber, 1992). These 

studies indicate that the response to deposition and survival following such an event is speciesspecific. Of the species examined, burial depths from which organisms were able to migrate to 

the surface ranged from 1 to 32 cm (0.4 to 12.6 in). If it is assumed that most benthos are not 

adversely affected by deposition of drilling muds less than 1 cm, benthos in the vicinity of the 

discharge receiving deposition in excess of this amount may be acutely impacted by drilling 

activities. 
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4.7.11.2.4. Exposure 

Aquatic fish and mammal exposure to harmful substances in this evaluation includes direct 

uptake or contact through absorption across the gills (for fish only) and ingestion of water, food, 

or sediments. Direct contact for avian species is through incidental ingestion of water and 

ingestion of food (prey species representative by salmonids). 

Frequency and duration

In addition to the toxicity studies, the determination of an effect involves some evaluation of 

exposure. The modeling used to estimate effluent drilling muds and cuttings may under or over 

estimate the concentrations depending on spatial and temporal variability as well as model error. 

Exposure duration is defined as the time period over which an organism is exposed to one or 

more contaminants. The exposure duration used in this evaluation is a daily average. The model 

was based on a daily average. It is expected that all actions in this permit were below acute 

levels at or near the discharge release. The determination of likelihood of adverse affects is 

based on an assumption that an average daily exposure is adequate to address the habitat 

preferences of the endangered species. 

Bioaccumulation

Ideally, to understand the relationship between the water column concentration and fish tissue, 

site-specific bioaccumulation factors (BAFs) are needed for each non-ionic organic compound of 

interest. BAFs account not only for uptake via water exposure, but also uptake through the food 

chain and the influence of sediment concentrations on both the food and water routes. Thus, sitespecific BAFs reflect the disequilibrium of the compound in the major components of the local 

system (water, sediment, organisms) and should not be transferred from one system to another 

without considering carefully the underlying assumptions in so doing. In general, one would 

prefer to develop and run a model for a specific location that reflects back the state of the system 

(i.e., describing how each compound is partitioning into organic matter in the water column and 

sediments, and into lipids in the organisms of different trophic states, and how higher level 

organisms are obtaining their tissue concentrations through food, water, and sediment 

exposures). 

Such a model and supporting data do not currently exist for the ecosystem in the vicinity of the 

discharges of oil and gas exploration facilities. The lack of estimating bioaccumulation for other 

organic chemicals results in an uncertainty in the effects for these chemicals. The resultant 

benchmarks may not be fully protective of the endangered species. 

Species Life history

While the life history of the species is discussed in general terms there may be site specific 

behavior or habitat factors which limit or alter the species preferences. A review of the scientific 
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literature found that younger life stages of fish are generally more sensitive to chemical toxicants 

than older fish. 

Effluent concentrations

Models and existing data were used to estimate how the proposed effluent limitations for drilling 

muds and cuttings could potentially cause exposure (magnitude, frequency, and duration). A 

discussion of the exposure volume model inputs and assumptions is provided in section 3.1.7. 

4.7.11.3. Field Studies 

Field studies were performed by the Sohio Alaska Petroleum Company (1981 & 1982) and 

Crippen et al. (1980) to monitor the environment fate associated with above ice disposal of 

drilling fluids and cuttings in the Beaufort Sea. However, these studies, which are discussed in 

Section 3.1.6.1, were only conducted in the Beaufort Sea area and were only for discharges of 

drilling muds and cuttings. No studies have been conducted in the Arctic environment for below 

ice or open water discharges. 

4.7.12. Issues of Take 

The purpose of this section is to assess whether or not take of a listed species is likely to result 

from the proposed activity. “Take” is defined as in Section 3(18) of the ESA means to “harass, 

harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt to engage in any such 

conduct”. The USFWS further defines “harm” as “significantly impairing behavioral patterns 

such as breeding, feeding, or sheltering”, and “harass” as “actions that create the likelihood of 

injury of listed species to such an extent as to significantly disrupt normal behavior patterns 

which include, but are not limited to, breeding, feeding or sheltering”. Further, the “incidental 

take” in Section 10(a)(1)(B) of the ESA means “any taking otherwise prohibited by Section 

9(a)(1)(B) if such taking is incidental to, and not the purpose of, the carrying out of an otherwise 

lawful activity”. Finally, a “take” may occur only to individuals of a species, not to a species' 

habitat or to designated critical habitat. The take prohibition does not extend to proposed or 

candidate species. 

Applying these definitions to the previous analysis, it is likely that an incidental take of bowhead 

whale, spectacled eider or Steller’s eider, in the form of harm and harassment, could occur. 

Harm would occur when a whale entered a mixing zone for feeding or breeding but was unable 

to perform these activities due to physiological alteration from exposure to TSS, metal, organic 

compounds, or toxicity. This, of course, is dependent on how long the whale remains within the 

impact area of these parameters. Harassment due to loss of prey species is a more likely 

scenario, which could occur to both whale and eider species within the Action Area. Exposure to 

toxic levels of chemical compounds or mixtures at toxic levels or that bioaccumulate to toxic 

levels would impair development or result in death to aquatic prey species. Another possible 

problem is the movement of the bowhead whale that could result in multiple exposures to some 

individuals. 
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4.8. ESSENTIAL FISH HABITAT 

Essential fish habitat (EFH) is the waters and substrate (sediments, etc.) necessary for fish to 

spawn, breed, feed, or grow to maturity. The Magnuson-Stevens Fishery Conservation and 

Management Act (January 21, 1999) requires EPA to consult with the NOAA Fisheries when a 

proposed discharge has the potential to adversely affect (reduce quality and/or quantity of) EFH. 

In the Area of Coverage, EFH has been established for red and blue king crabs, snow crabs, 

yellowfin sole, sculpins, and Pacific salmon (chinook, coho, pink, sockeye, and chum). Table 4-

8 presents the location and life stages of EFH species within the Area of Coverage. 

4.8.1. Red King Crab 

Red king crab (Paralithodes camtshaticus) is widely distributed throughout the Bering Sea. Red 

king crabs are typically at depths less than 100 fathoms (fm). Norton Sound has a discrete 

population of red king crab that is actively fished. The minimum size limit for harvest of male 

only crab from the Norton Sound population is 12 cm. The commercial fishery for red king crab 

in Norton Sound occurs in the summer, opening July 1 and a winter through the ice fishery opens 

November 15 and closes May 15. 

Egg hatch of larvae is synchronized with the spring phytoplankton bloom in Southeast Alaska 

suggesting temporal sensitivity in the transition from benthic to planktonic habitat. Early 

juvenile stage red king crabs are solitary and need high relief habitat or coarse substrate such as 

boulders, cobble, shell hash, and living substrates such as bryozoans and staked ascidians. 

Young-of-the-year occur at depths of 50 m or less. Late juvenile stage red king crabs of the ages 

of two to four years exhibit decreasing reliance on habitat and a tendency for the crab to form 

pods consisting of thousands of crabs. Podding generally continues until four years of age (about 

6.5 cm when the crab move to deeper water and join adults in the spring migration to shallow 

water for molting and mating. The approximate upper size limit of juvenile female and male red 

king crabs in Norton Sound at 50 percent maturity is 7 and 9 cm carapace length, respectively. 

While red king crab juveniles primarily feed on diatoms and hydroids; juvenile crabs are 

cannibalistic during molting. 

King crab molt multiple times per year through age 3 after which molting is annual. At larger 

sizes, king crab may skip molt as growth slows. Females grow slower and do not get as large as 

males. Female red king crabs in the Norton Sound area reach 50% maturity at 6.8 cm and do not 

attain maximum sizes found in other areas. Mature red king crabs exhibit seasonal migration to 

shallow waters for reproduction. The remainder of the year, red king crabs are found in deep 

waters. Males grasp females just prior to female molting, after which the eggs (43,000 to 

500,000) are fertilized and extruded on the female’s abdomen. The female red king crab carries 

the eggs for 11 months before they hatch, generally in April. Natural mortality of adult red king 

crab is estimated at about 25 percent per year due to old age, disease, and predation. Pacific cod 

is the main predator on red king crabs. Walleye Pollock, yellowfin sole, and Pacific halibut are 

minor consumers of pelagic larvae, settling larvae, and larger crabs, respectively. Adult king 
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crab feed on mollusks, echinoderms, polychaetes, decapods, crustaceans, algae, urchins, 

hydroids and sea stars. 

4.8.2. Blue King Crab 

Blue king crab (Paralithodes platypus) has a discontinuous distribution throughout their range 

(Hokkaido, Japan to Southeast Alaska). There are no distinct stocks of blue king crab that are 

fished within the Area of Coverage. 

Early juvenile blue king crabs require refuge substrate characterized by gravel and cobble 

overlaid with shell hash, and sponge, hydroid and barnacle assemblages, while late juveniles 

require nearshore rocky habitat with shell hash. Blue king crab molt multiple times as juveniles; 

skip molting occurs with increasing probability for those males larger than 10 cm carapace 

length. The approximate upper size limit of juvenile female and male blue king crabs at 50 

percent maturity is 9 and 12 cm carapace length, respectively. Unlike red king crab, juvenile 

blue king crabs do not form pods, instead relying on cryptic coloration for protection from 

predators. 

Mature blue king crabs occur most often between 45-75 m depth on mud-sand substrate adjacent 

to gravel rocky bottom. Adult male blue king crabs occur at an average depth of 50 m and an 

average temperature of 0.6 degrees C while females are found in a habitat with a high percentage 

of shell hash. Larger female blue king crabs have a biennial ovarian cycle and a 14 month 

embryonic period. Fecundity of females range from 50,000-200,000 eggs per female. It is 

suggested that spawning may depend on availability of nearshore rocky-cobble substrate for 

protection of females. Larger older crabs disperse farther offshore and are though to migrate 

inshore for molting and mating. Pacific cod is a predator on blue king crabs. 

4.8.3. Snow Crab 

Snow crabs (Chonoecetes opilio) are distributed on the continental shelf of the Bering Sea and 

Chukchi Sea. Snow crabs are thought to be of one stock in the Bering Sea. In the Bering Sea, 

snow crabs are common at depths less than 200 m. The eastern Bering Sea population within 

U.S. waters is managed as a single stock; however, the distribution of the population extends into 

Russian waters to an unknown degree. Only male crab greater than 7.8 cm carapace width may 

be harvested; however, a market minimum size of about 10.2 cm carapace width is generally 

observed. Most male snow crabs are though to enter the fishery at around age 6. The season 

opening date is January 15. 

Snow crab larvae mainly feed on diatoms, algae and zooplankton. Larvae of the snow crab are 

found in early summer and exhibit diel migration. The last of 3 larval stages settles onto bottom 

in nursery areas. Shallow water areas of the Eastern Bering Sea are considered nursery areas for 

snow crabs and are confined to the mid-shelf area due to the thermal limits of early and late 

juvenile life stages. A geographic cline in size of snow crabs indicates a large number of 

morphometrically immature crabs occur in shallow waters less than 80 m. The approximate 

upper size limit of juvenile female and male snow crabs at 50 percent maturity is 5 and 6.5 cm 
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carapace width, respectively. While snow crab juveniles primarily feed on crustaceans, 

polychaetes, mollusks, diatoms, algae and hydroids; juvenile crabs are cannibalistic during 

molting. 

The median size of maturity for male snow crabs is 6.5 cm carapace width (approximately 4 

years old). Males larger than 6 cm grow at about 2 cm per molt, up to an estimated maximum 

size of 14.5 cm carapace with, but individual growth rates vary widely. While 50 percent of the 

females are mature at 5 cm carapace width, the mean size of mature females varies from 6.3-7.2 

cm carapace width. Females cease growing with a terminal molt upon reaching maturity, and 

rarely exceed 8 cm carapace width. Female snow crabs are acknowledged to attain terminal molt 

status at maturity. Primiparous female snow crabs mate January through June and may exhibit 

longer egg development period and lower fecundity than multiperous female crabs. Multiparous 

female snow crabs are able to store spermatophores in seminal vesicles and fertilize subsequent 

egg clutches without mating. At least two clutches can be fertilized from stored speratophores, 

but the frequency of this occurring in nature is not known. Females carry clutches of 

approximately 36,000 eggs and nurture the embryos for approximately one year after 

fertilization. However, fecundity may decrease up to 50 percent between the time of egg 

extrusion and hatching, presumably due to predation, parasitism, abrasion or decay of 

unfertilized eggs. Brooding probably occurs in depths greater than 50 m. Changes in proportion 

of morphometrically mature crabs by carapace width have been related to an interaction between 

cohort size and depth. Natural mortality of adult snow crab is estimated at about 25 percent per 

year. Pacific cod, sculpins, and pollock are the main predator on snow crabs in terms of 

biomass. Other predators include yellowfin sole, flathead sole, Alaska plaice, walleye Pollock, 

Pacific halibut, rock sole, skates, bearded seals and walrus. Adult snow crab feed on 

polychaetes, brittle stars, mollusks, crustaceans, hydroids, algae and diatoms. 

4.8.4. Yellowfin Sole 

Yellowfin sole (Limanda aspera) is distributed in North American waters from off British 

Columbia, Canada (approximately latitude 49° N), to the Chukchi Sea (about latitude 70° N) and 

along the Asian coast to about latitude 35° N off the South Korean coast in the Sea of Japan. 

Fishery recruitment begins at about age six and they are fully selected at age 13. Historically, 

the fishery has occurred throughout the mid and inner Bering Sea shelf during ice-free 

conditions, although much effort has been directed at the spawning concentration in nearshore 

northern Bristol Bay. 

Juvenile yellowfin sole are separate from the adult population, remaining in shallow areas until 

they reach approximately 15 cm. The estimated age of 50 percent maturity is 10.5 years 

(approximately 29 cm) for females based on samples collected in 1992 and 1993. The 

approximate size limit of juvenile fish is 27 cm. Juvenile yellowfin sole feed on polychaetes, 

bivalves, amphipods and echiurids. 

Adult yellowfin sole exhibit a benthic lifestyle and occupy separate winter spawning and 

summertime feeding distributions on the eastern Bering Sea shelf. From over-winter grounds 

near the shelf margins, adults begin a migration onto the inner shelf in April or early May each 
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year for spawning and feeding. Adults feed mainly on bivalves, polychaetes, amphipods and 

echiurids. During wintertime migration to deeper waters of the shelf margin to avoid extreme 

cold water temperatures, their feeding diminishes. Natural mortality rate is believed to range 

from 0.12-0.16. Groundfish predators include Pacific cod, skates and Pacific halibut, mostly on 

fish ranging from 7-25 cm length. 

4.8.5. Sculpins 

Sculpins (cottidae) are a large circumboreal family of demersal fishes in the Bering Sea, 

including Yellow Irish lords (Hemilepidotus jrodani), Red Irish lords (Hemilepoditus 

hemilepidotus), Butterfly sculpin (Hemilepidotus papilio), Bigmouth sculpin (Hemitripterus 

bolini), Great sculpin (Myoxocephalus polyacanthocephalus), and Plain sculpin (Myoxocephalus 

jaok). Yellow Irish lords are distributed from subtidal areas near shore to the edge of the 

continental shelf (down to 200 m) throughout the Bering Sea. Red Irish lords, however, are 

distributed from rocky, intertidal areas to about 100 meter depth on the middle continental shelf 

(most are shallower than 50 m) throughout the Bering Sea. Butterfly sculpins are distributed in 

the Bering Sea and Chukchi Sea in depths of 20-250 m. Bigmouth sculpin are distributed in 

deeper waters offshore, between about 100-300 m in the Bering Sea. Great sculpin are 

distributed from the intertidal areas to 200 m, but may be most common on sand and muddy/sand 

bottoms in moderate depths (50-100 m) throughout the Bering Sea. Plain sculpin are distributed 

throughout the Bering Sea from intertidal areas to depths of about 100 meters, but most common 

in shallow waters (<50 m). Sculpins are not a target of groundfish fisheries in the Bering Sea, 

but are a bycatch from bottom trawl fisheries for flatfish, Pacific cod and Pollock; almost all is 

discarded. Annual sculpin bycatch has ranged between 1 and 4 percent of the annual survey 

biomass estimates, however little is known of the species distribution of the bycatch. 

Sculpins live in a broad range of habitats from rocky intertidal pools to muddy bottoms of the 

continental shelf, and rocky, upper slope areas. Most species live in shallow water or in 

tidepools, but some inhabit the deeper waters (to 1,000 m) of the continental shelf and slope. 

Most species do not attain a large size (generally 10-15 cm), but those that live on the continental 

shelf and are caught by fisheries can be 30-50 cm. Sculpins generally eat small invertebrates 

(e.g., crabs, barnacles, mussels), but fish are included in the diet of larger species. 

4.8.6. Pacific Salmon 

Salmon essential fish habitat in freshwaters of Alaska is designated as virtually all the coastal 

streams to about 70° N. latitude. Salmon essential fish habitat in marine waters of Alaska 

formally is designated as the area within the 320 km exclusive economic zone boundary of the 

United States down to a depth of 500 m (North Pacific Fisheries Management Council, 1998). 

Salmon essential fish habitat is defined to the outer boundary of the exclusive economic zone 

and to a depth of 500 m, while the written descriptions of salmon indicate that in the juvenile 

marine stage, they (all five species) head to the Bering Sea and south to the Gulf of Alaska for 

this stage (North Pacific Fisheries Management Council, 1998). 
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Habitat areas of particular concern (HAPC) include nearshore areas of intertidal and submerged 

vegetations, rock, and other substrates. Shallow nearshore estuarine and marine habitats 

including submerged aquatic vegetations and emergent vegetation are habitat areas of particular 

concern used by Pacific Salmon. Substrates of high-micro habitat diversity serving as cover from 

groundfish and other organisms such as areas rich in epifauna communities or substrate with 

large participle size such as the Boulder Patch. Streams and lakes and other freshwater areas used 

by Pacific salmon and other anadromous fish (such as smelt), especially located near urban areas 

or areas with intensive human-induced developmental activities also are habitat areas of 

particular concern (North Pacific Fisheries Management Council, 1998). 

Essential Fish Habitat for the salmon fisheries off the coast of Alaska consists of the aquatic 

habitat, freshwater and marine, necessary to allow for salmon production needed to support a 

long-term sustainable salmon fishery and salmon contributions to healthy ecosystems. Since this 

federal action only occurs in marine waters, this discussion only addresses EFH in marine 

waters. 

4.8.6.1. Pink Salmon 

Pink salmon (Oncorhynchus gorbuscha) are widely distributed throughout the Bering Sea; 

however, north, east and west of the Bering Straight, spawning populations become more 

irregular and occasional. Pink salmon are not a major fishery in the Area of Coverage. 

The timing and pattern of seaward dispersal is influenced by many factors, including general size 

and location of the spawning stream, characteristics of adjacent shoreline and marine basin 

topography, extent of tidal fluctuations and associated current patterns, physiological and 

behavioral changes with growth, and different genetic characteristics of individual stocks. When 

newly emerged pink salmon fry migrate from freshwater to marine waters, they tend to remain 

along the shoreline for several weeks in shallow water of only a few centimeters deep to feed. 

Juvenile pink salmon in the Bering Sea off the northeastern Kamchatka coast are found in one of 

three hydrological zones during their first three to four months of marine life: (1) the littoral 

zone, up to 150 m from shore; (2) open parts of inlets and bays from 150 meters to 3.2 km from 

shore; and (3) the open parts of the large Karaginskiy Gulf, 3.2 to 96.5 km from shore. 

Distributuion within these regions is seasonally related to the size of pinks, with an offshore 

movement of larger fish in August and September. The approximate size limit of juvenile fish is 

25 cm. 

Pink salmon juveniles routinely obtain large quantities of food sufficient to sustain rapid growth 

from a broad range of habitats providing pelagic and epibenthic foods. Collectively, diet studies 

show that pink salmon are both opportunistic and generalized feeders and on occasion they 

specialize in specific prey items. Diel sampling of stomachs showed fewer and more digested 

food items at night than during the day indicating that juvenile pinks are primarily diurnal 

feeders. In the marine environment, pink salmon fry and juveniles are food for a host of other 

fishes and coastal seabirds. 
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The population biology of pink salmon revolves around a two-year life cycle. Entering the 

estuary as a fry at around 3 cm in length, maturing adults return to the same area 14-16 months 

later ranging in length from 45 to 55 cm. Pink salmon adults feed on fish, squid, euphausiids, 

amphipods and copepods. In the marine environment, subadult and pink salmon are known to be 

eaten by fifteen different marine mammals, sharks, other fishes (e.g., Pacific halibut), and 

humpback whales. Because pink salmon are the most abundant salmon, it is likely they 

comprise a significant portion of the salmonids eaten by marine mammals. 

4.8.6.2. Chum Salmon 

Chum salmon (Oncorhynchus keta) are widely distributed throughout the Bering Sea, Arctic 

Ocean, Chukchi Sea, and Beaufort Sea to the Mackenzie River delta. Major fisheries occur for 

chum salmon southward of the Noatak River in the Hope Basin. Chum salmon are often 

captured incidently in fisheries targeting pink or sockeye salmon. Chum salmon have also been 

captured incidentally in the trawl fisheries for Pollock in the Bering Sea. 

Chum salmon fry migrate (mostly at night) out of the streams directly to the sea shortly after 

emergence. This outmigration occurs between February and June, but most fry leave the streams 

during April and May. Chum salmon do tend to linger for several months to forage in the 

intertidal areas (intertidal grass flats and along the shore) at the head of bays before actively 

migrating into channels on the way to the outside waters. Therefore, estuaries are very important 

for chum salmon rearing during spring and summer as most juveniles are present in coastal 

waters during this time period. Offshore movement of larger juveniles occurs mostly in JulySeptember. Juvenile chum salmon are thought to leave the coastal waters and move south into 

the North Pacific Ocean between Kodiak and False Pass during late fall. After chum salmon 

form an annulus on their scales (January-March) they are considered immature. They may 

remain immature for several years until they start maturing and begin their migration to their 

spawning streams. In Alaska, chum salmon return from the ocean to spawn between June and 

November. Juvenile chum salmon utilize a wide variety of food items, including mostly 

invertebrates (including insects), and gelatinous species. 

Chum salmon reside in the ocean for about one to six years. Adults mature at ages 2 through 7 

years; 4-, 5- and 6-year old chum salmon dominate the northern stocks. Recently, immature and 

maturing chum salmon from Washington, British Columbia, and southeast Alaska have been 

identified in the Bering Sea in August. Chum salmon eat a variety of foods during their ocean 

life (e.g., amphipods, euphausiids, pteropods, copepods, fish and other species of salmon. Chum 

salmon have two habitat requirements that are essential in their life history that make them very 

vulnerable: (1) reliance on upwelling ground water for spawning and incubation, and (2) reliance 

on estuaries/tidal wetlands for juvenile rearing after migrating out of freshwater streams. 

The 1976-77 Regime Shift in the North Pacific Ocean created very favorable ocean conditions 

for all species of salmon from northern British Columbia to northern Alaska that resulted in 

increased stock abundance in the mid-1990s. However, as the abundance increased age at 

maturity increased and the size at age decreased drastically. Chum salmon of the same age in the 
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early 1990s weighed up to 46 percent less than they weighed in the early 1970s. These changes 

in size and age at maturity as population numbers increased suggests that there may be carrying 

capacity limits for chum salmon under certain conditions. 

4.8.6.3. Sockeye Salmon 

Sockeye Salmon (Oncorhynchus nerka) are widely distributed throughout the Bering Sea; 

however, populations become more irregular and occasional north of the Bering Strait. In 

marine environments, sockeye salmon occupy ocean waters south of their spawning systems. 

The approximate size limit of juvenile fish is 25 cm. Typically, juvenile anadromous sockeye 

utilize lake rearing areas for one to three years after emergence, however, some populations 

utilize stream areas for rearing and migrate to sea soon after emergence. Emergent fry feed in 

the stream or low-salinity estuaries for several months before migrating to offshore ocean areas. 

These sea-type sockeye smolts are typically the same size as yearling smolts [average range of 

60-125 mm and 2-30 grams (g)] when they migrate to offshore ocean areas. After smoltification 

and exodus from natal river systems in spring or early summer, juvenile sockeye enter the marine 

environment. Depending on the stock, they may reside in the estuarine or nearshore environment 

before moving into oceanic waters. They are typically distributed in offshore waters by autumn 

following outmigration. During the initial marine period, yearling sockeye forage actively on a 

variety of organisms, apparently preferring copepods and insects, but also eating amphipods, 

euphausiids, and fish larvae when available. In the marine environment, sockeye salmon 

juveniles are food for may other fishes and coastal sea birds. 

Sockeye may spend from one to four years in the ocean before returning to fresh water to spawn 

and die in late summer and fall. Sockeye salmon from different regions differ in growth rate as 

well as age and size at maturity. Growth in length is greatest during the first year at sea and 

increase in weight is greatest during the second year. Adult sockeye salmon consume copepods, 

insects, amphipods, small fish and squid. Measured marine survivals of sockeye salmon, from 

entry of smolts into stream mouth estuaries to returning adults, have ranged from about 5-50 

percent. In general, it is believed that much of the natural mortality of sockeye salmon juveniles 

in the marine environment occurs within the first few months, and is probably influenced by 

three factors of unknown relative importance: (1) size and age at seaward migration; (2) timing 

of entry into the marine environment; and (3) length of stay in the ocean. Variations in 

oceanographic conditions and in marine predator populations (fish, mammals and birds) 

undoubtedly have affected the marine survival of sockeye populations in different ways around 

the North Pacific rim, but these effects are poorly understood. They are known to be eaten by 

marine mammals and sharks. 

4.8.6.4. Chinook Salmon 

Chinook salmon (Oncorhynchus tshawytscha) range widely throughout the Bering Sea, but has 

been identified as far as the Mackenzie River that discharges into the Beaufort Sea. The largest 
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river systems (e.g., Yukon River) tend to support the largest aggregate runs of chinook salmon 

and have the largest individual spawning populations. 

Chinook salmon are highly prized by commercial, sport, and subsistence fishers because of their 

large size and excellent palatability. In Alaska, approximately 1 million chinook salmon are 

harvested annually. Because of their distribution in the water column, the majority of the 

chinook salmon harvested in commercial troll fisheries are caught at depths of 30 m or greater, 

and chinook salmon is the most common salmon species taken as bycatch in mid-water and 

bottom trawl fisheries. In most of Alaska, there is no direct harvest of chinook salmon in the 

EEZ; the FMP for salmon in the Alaska EEZ prohibits commercial harvest in this area, with few 

exceptions. Most of the fishing effort takes place in the coastal or riverine waters of the State. 

The regulatory minimum size used in the Alaska hook-and-line fisheries is 71 cm total length. 

Chinook salmon demonstrate variable ocean migration patterns and timing of spawning 

migrations. This variation in life history strategy has been explained by separating chinook 

salmon into two races: stream- and ocean-type fish. Stream-type fish have long freshwater 

residence as juveniles (1-2 years), migrate rapidly to oceanic habitats, enter freshwater as 

immature or “bright” fish, and spawn far upriver in late summer or early fall. Ocean-type fish 

have short, highly variable freshwater residency (from a few days to 1 year), extensive estuarine 

residency, enter fresh water at a more advanced state of maturity, and spawn within a few weeks 

of freshwater entry in lower portions of the watershed. Within these two types, there is also 

substantial variability due to a combination of phenotypic plasticity and genetic selection to local 

conditions. For example, adult run-timing is strongly influenced by in-river flow volumes and 

temperature levels. 

Chinook salmon are typically 33-36 mm in length when they emerge from the incubation gravel. 

Residency in freshwater and size and timing of seawater migration are highly variable. Since 

chinook salmon can mature at ages of 2-8 years, the term ‘juvenile’ is better defined by 

physiological progress of maturation rather than threshold size. Ocean-type fish can migrate 

seaward immediately after yolk absorption. The majority of ocean-type fish migrate at 30-90 

days after emergence, but some fish move seaward as fingerlings in the late summer of their first 

year, while others overwinter and migrate as yearling fish. Stream-type fish, in contrast, 

generally spend at least one year in freshwater, migrating as one- or two-year old fish. In 

Alaska, the stream-type life history predominates although ocean-type life histories have been 

documented in a few Alaska watersheds. Water and habitat quality and quantity determine the 

productivity of a watershed for chinook salmon. Both stream- and ocean-type fish utilize a wide 

variety of habitats. The seaward migration of smolts is timed so that the smolts arrive in the 

estuary when food is plentiful. Migration and rearing habitats overlap. Stream flows during the 

migratory period tend to be high, which facilitates seaward movement and provides some 

sheltering from predation. After entering saltwater, chinook juveniles disperse to oceanic 

feeding areas. Ocean-type fish have more extended estuarine residency, tend to be more coastal 

oriented, and do not generally migrate as far as stream-type fish. Food in estuarine areas 

includes epibenthic organisms, insects, and zooplankton. 

Chinook salmon typically remain at sea for 1 to 6 years. They have been found in oceanic 

waters at temperatures ranging from 1-15° C. Chinook salmon occur over a broad geographic 
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range, encompassing different ecotypes and very diverse habitats. Ocean distribution patterns 

have been shown to be influenced by both genetics and environmental factors. Migratory 

patterns in the ocean may have evolved as a balance between the benefits of accessing specific 

feeding grounds and the energy expenditure and dispersion risks necessary to reach them. 

Across the geographic range which the species has colonized, populations of chinook salmon 

have developed localized adaptations to site specific characteristics. These local adaptations 

result in different and diverse characteristics of biological importance, including timing of 

spawning, adult and juvenile migration timing, age and size at maturity, duration of freshwater 

residency, and ocean distribution. Currently there is little data for the estuarine and marine 

habitats beyond presence/absence or density information. 

Chinook salmon are the distributed deeper in the water column. They are most abundant at 

depths of 30-70 m and are often associated with bottom topography. Because of their relatively 

low abundance in coastal and oceanic waters, chinook salmon in the marine environment are 

typically only an incidental food item in the diet of other fishes, marine mammals, and coastal 

sea birds. Chinook salmon are the most piscivorous of the Pacific salmon; fish make up the 

largest component of their diet at sea, although squid, pelagic amphipods, copepods, and 

euphausiids are also important at times. 

4.8.6.5. Coho Salmon 

Coho salmon (Oncorhynchus kisutch) are widely distributed in cool areas of the Bering Sea and 

most adjoining fresh and estuarine waters. In Alaska, most coho are wild fish with a distribution 

north to Point Hope on the eastern Chukchi Sea. Coho is an important commercial, sport, and 

subsistence fishery in the Area of coverage; catch is at historically high levels and trends in 

abundance of most stocks are rated as stable. Fisheries in the Alaska Region primarily target 

adult coho and take place in coastal marine migration corridors, near the mouths of rivers and 

streams, and in freshwater migration areas. Those fisheries coincide with migrations toward 

spawning areas from July through October. 

In fall, juveniles may migrate from summer rearing areas to areas with winter habitat. Such 

juvenile migrations may be extensive within the natal stream basin or between basins through 

salt water or connecting estuaries. Seaward migration of coho smolts occurs usually after 1-2 

years in fresh water. The migration is timed primarily by photoperiod and occurs in spring, 

usually coincident with the spring freshet. At sea, juvenile Adult coho are highly migratory and 

depend on suitable habitat in their migration routes. Alaska coho generally migrate north and 

offshore into the Bering Sea. Unobstructed passage and suitable water depth, water velocity, 

water quality, and cover are important elements in all migration habitats. Juvenile coho 

primarily use estuarine habitat during their first summer and also as they are leaving fresh water 

during their seaward migration. Intertidal section of freshwater streams (i.e., stream-estuary 

ecotones) can be important rearing habitat for coho from May to October. These areas may 

account for one-quarter of the juvenile production in small streams. Growth in these areas is 

particularly rapid because of abundant invertebrate food. Habitats used include glides and pools 

during low tide, and coho occupy the freshwater lens during high tide. In fall, juvenile coho 
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move upstream to overwinter in freshwater. After leaving freshwater, coho spend up to four 

months in coastal waters before migrating offshore and dispersing throughout the Bering Sea. 

Offshore, juvenile salmon are concentrated over the continental shelf within 37 km of shore 

where the shelf is narrow, but may extend to at least 74 km from shore in some areas. Stockspecific aggregations have not been noted at this stage. Marine invertebrates are the primary 

food when coho first enter salt water, and fish prey increase in importance as the coho grow. 

Juveniles are eaten by a variety of birds (e.g., gulls, terns, kingfishers, cormorants, mergansers, 

herons) and fish (e.g., Dolly Varden, steelhead, cutthroat trout, and arctic char). Juvenile coho 

are also significant predators of pink salmon fry during their seaward migration. 

Most coho remain at sea for about 15 months before returning to coastal areas and entering fresh 

water to spawn, although some males will return to spawn after about six months at sea. They 

occupy epipelagic areas in the Bering Sea during the 12 to 14 month after leaving coastal areas. 

Some coho also use coastal and inshore waters at this life stage, but those are likely to be smaller 

at maturity. The spacial distribution of suitable habitat conditions is affected by annual and 

seasonal changes in oceanographic conditions; however, coho generally use offshore areas of the 

Bering Sea. The distribution of ocean harvest is generally more northerly than that for stocks 

from other regions. Growth is controlled mainly by food quantity, food quality, and temperature. 

Food for salmon is most abundant above the halocline which may range from 100 to 200 m in 

depth. Coho growth is best in epipelagic offshore habitat where forage is abundant and sea 

surface temperature is between 12 and 15° C; coho rarely use areas where sea surface 

temperature exceeds 15° C. Adult coho provide important food for bald eagles, marine 

mammals (e.g., Steller sea lion, harbor seal, beluga, and orca), and salmon sharks. 

4.8.7. Effects Analysis 

The EPA has determined that the issuance of this permit is not likely to adversely modify the 

critical habitat for red and blue king crabs, snow crabs, yellowfin sole, sculpins, pink 

salmon, and chum salmon, chinook salmon, coho salmon, and sockeye salmon in the vicinity 

of the discharge for the following reasons: 

• The proposed permit has been developed in accordance with the Alaska water quality 

standards to protect aquatic life species in marine waters. NPDES permits are established 

to protect water quality in accordance with State water quality standards. The standards 

are developed to protect the designated uses of the waterbody, including growth and 

propagation of aquatic life and wildlife. Self-monitoring conducted by the industry 

indicates that the facilities covered under this general permit will be able to comply with 

all limits of the proposed permit. 

• The derivation of permit limits and monitoring requirements (refer to Section II and 

Appendix A and B of the fact sheet for specifics pertaining to the proposed permit) for an 

NPDES discharger are in accordance with state water quality standards using procedures 

prescribed in EPA guidance (USEPA, 1991). 
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• The majority of activity under this permit will occur in the Beaufort Sea; it is unlikely 

that activity will occur in the Chukchi Sea, Hope Basin or Norton Basin (MMS, 2002). 

Generally, there is little evidence of viable self-sustaining salmon populations in the 

Beaufort Sea. 

• Drilling mud disposal will not affect the major prey, zooplankton, or fish or their habitats. 

• Discharges of drilling fluids and drilling cuttings may impact minor prey, benthic 

organisms (at sublethal levels), and benthic habitat, which in turn will impact critical 

habitat for EFH species. However, the impact areas are small (less than 100 m radius) 

per discharger, the expected total number of discharges is small (37 total wells; 23 

exploration wells and 14 delineation wells), and the recovery period of impacted benthos 

is estimated to be less than two years. 

• While no specific demersal fish spawning locations have been identified in any of the 

Arctic areas of coverage, a number of essential fish species possess demersal eggs. 

Although unlikely during exploratory activities in the Area of Coverage due to the 

anticipated emphasis on deeper offshore drilling sites, demersal eggs could be smothered 

if discharge in a spawning area coincides with the period of egg production. Exploratory 

operations in state waters are more likely to adversely impact demersal fish spawning 

activities because spawning grounds are more commonly found in nearshore waters. The 

potential of drilling muds and cuttings to smother demersal fish eggs is probably the most 

serious potential impact of exploratory drilling to fish species. 

4.9. CUMULATIVE EFFECTS ANALYSIS 

This analysis only considers past, present, and reasonably foreseeable future exploration 

discharges to biological resources. MMS (1982, 1991, 2002, 2003) and ADNR (1999) have 

conducted cumulative effect analysis of exploration activities in the broader sense of the impact 

on the environment which results from the incremental impact of the action when added to the 

other past, present, and reasonably foreseeable future actions of all activities (federal and nonfederal). 

Impacts of any kind from a single drilling site are likely to be localized. Although benthic 

organisms may be smothered or develop body burdens of heavy metals above background in 

localized areas, the benthic and epontic (ice-associated) communities in the Arctic areas of 

coverage would not be expected to decline significantly. However, no data exist to evaluate the 

potential impact to benthic and epontic communities for several drilling sites that would be 

located close enough to each other that dispersion of the discharged muds from all of the sites 

would cumulatively cover a large contiguous portion of the area. 

Impacts from bioaccumulation, toxicity and changes in community structure could be cumulative 

spatially and over the short term, but it is unlikely that these impacts would be persistent. In 

addition, lessening impacts can reasonably be expected over time. Although more complete 

knowledge would be of value in assessing the magnitude and significance of cumulative 
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environmental impact, available data indicate that unreasonable degradation is not likely to occur 

in areas of adequate dispersion and dilution. 

Another factor to be considered in assessing the environmental impacts from drilling discharges 

is the susceptibility of the area to periodic storm surges. These events could, by redistributing 

localized platform discharges, consequently redistribute the zone of impact. 

4.10. CONSERVATION MEASURES 

The general permit has several conservation measures that would reduce the impact to biological 

resources. These conservation measures are discussed in the following sections. 

4.10.1. Area Restrictions 

The permittee is prohibited from discharging: 

• In water depths less than 5 m (as measured from MLLW); 

• Between the shore (mainland and the barrier islands) and the 5-m isobath; 

• Within 1000 m of the Steffansson Sound Boulder Patch (near the mouth of the 

Sagavanirktok River) or between individual units of the Boulder Patch where the 

separation between units is greater than 2000 m but less than 5000 m; 

• Within 1000 m of Thetis Island and Colville River Delta; 

• Within Omalik Lagoon; 

• Within Kasegaluk Lagoon; or 

• Within 3 mi of the following passes of Kasegaluk Lagoon: Kukpowruk Pass, Akunik 

Pass, Utukok Pass, Icy Cape Pass, Alokiakatat Pass, Naokok Pass, and Pingaorarok Pass. 

4.10.2. Seasonal Restrictions 

• The permittee is prohibited from discharging in open waters at depths greater than 1 

meter below the surface of the receiving water between the 5 and 20 m isobaths as 

measured from the MLLW during open-water conditions or within 1000 m of river 

mouths or deltas. 

• The permittee is prohibited from discharging during unstable or broken ice conditions 

within 1000 m of river mouths or deltas or shoreward of the 20 meter isobath as 

measured from the MLLW during unstable or broken ice conditions except when the 

discharge is prediluted to a 9:1 ratio of seawater to drilling fluids and cuttings, and the 

permittee conducts the environmental monitoring required under paragraph B.5 of the 

general permit. 

• The permittee is prohibited from discharging below the ice during stable ice conditions 

and shall avoid, to the maximum extent possible, areas of sea ice cracking or major stress 

fracturing unless authorized otherwise from the EPA. 
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4.10.3. Environmental Monitoring Requirements 

The permittee is required to conduct the environmental monitoring requirements of this section 

when the authorization to discharge is within 4000 m of the prohibited areas discussed in 

sections 4.10.1 and 4.10.2, above. The permittee must submit a plan of study for the 

environmental monitoring program to the EPA and the Alaska Department of Environmental 

Conservation (ADEC) for review with the notice of intent (NOI) (i.e., the application for 

coverage under the general permit). The permittee must incorporate any changes required by the 

EPA or ADEC in the monitoring program’s design. A copy of the final study plan must be sent 

to the North Slope Borough. The permittee must include in the environmental monitoring study 

plan relevant hydrographic, sediment hydrocarbon, and heavy metal data from surveys 

conducted before and during drilling fluid disposal operations and up to at least one year after 

drilling operations cease. The permittee must submit an annual report to the EPA by March 1st 

of the following year. Copies of the report must be sent to ADEC and the North Slope Borough. 

Further requirement for environmental monitoring are found in Appendix C (NPDES general 

permit, section II.B.5, page 15). 

4.10.4. Limitation on Number of Wells Drilled 

The permittee is limited to drilling discharges from no more than five wells at a single drilling 

site, although additional wells may be drilled upon approval by the EPA. Specific requirements 

are found in Appendix C (NPDES general permit, section II.B.6, page 17). 

4.10.5. Restrictions on Discharges of Mineral Oil Pills 

The permittee is authorized to discharge residual amounts of mineral oil pills (mineral oil plus 

additives) under the conditions set forth in Appendix C (NPDES general permit, section II.B.8, 

page 17). 

4.10.6. Toxicity Testing Requirements 

In order to determine potential toxic effects of the discharge, the permit requires regular SPP 

toxicity testing of effluent from discharge 001. The test species required for this permit include 

Mysidopsis bahia. Toxicity tests focus on the sensitive life stage of the test species on the 

assumption that protection of this stage will protect the species as a whole. These species are 

currently the best available surrogates for assessing impacts on the listed fish species and, 

therefore, toxicity testing using these species will give an indication of toxicity from the whole 

effluent. See Attachment 4 of the permit located in Appendix C for more details regarding the 

drilling fluids toxicity requirements. 

4.10.7. Quality Assurance Plan 
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The permit requires the development and implementation of a Quality Assurance Plan (QAP) to 

assist in planning for the collection and analysis of effluent and receiving water samples in 

support of the permit and to explain data anomalies if they occur. All monitoring is required to 

use the EPA Methods published in 40 CFR §136. The QAP must specify analytical methods to 

achieve these method detection limits. See section IV.A of the permit located in Appendix C for 

more details regarding the QAP requirements. 

4.10.8. Best Management Practices Plan 

Best management practices (BMPs) are measures that are intended to prevent or minimize the 

generation and the potential for release of pollutants from industrial facilities to waters of the 

U.S. The permit requires the permittee to prepare and implement a BMP plan to minimize the 

quantity of pollutants discharged, reduce the toxicity of the discharges to the extent practicable, 

prevent the entry of pollutants into waters, and minimize storm water contamination. See section 

IV.B of the permit located in Appendix C for more details regarding the BMP plan requirements. 

4.10.9. Drilling Fluid Plan 

The drilling fluid (mud) plan is one component of the Best Management Practices Plan. The 

drilling fluid plan requirement is also based upon the Pollution Prevention Act (PPA) and its 

policy of prevention, reduction, recycling, and treatment or wastes (PPA Section 102(b)) through 

measures that include process modification, materials substitution, and improvement of 

management (PPA Section 107(b)(3)). The goal of requiring development of a drilling fluid plan 

is to ensure that personnel on-site are knowledgeable about the information needed and the 

methods required to formulate the mud/additive systems in order to meet the effluent toxicity 

limit. The intent of the mud plan is a written guide to planning for and using a mud/additive 

system in compliance with the permit. To date, Alaskan operators have demonstrated that 

thorough planning and evaluation of mud/additive systems with respect to possible cumulative 

toxicity does consistently result in discharge of muds that are less toxic than the required 

limitation. 

The mud plan is intended to demonstrate that the discharged mud/additive system for the well in 

question will meet the effluent limitation based on the following decision criteria: 

• Estimates of worst case cumulative discharge toxicity (either calculated or 

actual toxicity test results); 

• Estimates of toxicity of discharged mud when a mineral oil pill has been 

used; and 

• Use of less toxic alternatives, where possible. 

The mud plan is also required to include a clearly stated procedure for dealing with situations in 

which additives not originally planned for are needed at the last minute. This procedure should 

enable drilling and mud personnel to determine whether an additive or mud component may be 

added to the circulating mud system without significant effect upon the discharge toxicity. 

Criteria for reaching this type of last minute additive decision are required to be clearly specified 
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in the drilling fluid plan. See section IV.C of the permit located in Appendix C for more details 

regarding the drilling fluid plan requirements. 
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5.0 HUMAN HEALTH 

This section provides a discussion of the impact to human health exposure of discharges 

associated with oil and gas exploration activities within the Beaufort Sea, Chukchi Sea, Hope 

Basin, Norton Basin, and adjacent state waters. Since it is most likely that exploration activities 

will occur in the Beaufort Sea area, this evaluation mainly takes into account exposures in that 

are likely to occur in that area, although the other areas are also discussed. 

Ecological resources for human consumption within the nearshore marine environment were the 

basis for this analysis because available information suggests that effects of discharges are more 

likely to occur there. This area generally includes nursery areas since larval and juvenile forms 

are considered the life stages most sensitive to discharges of wastes. The nearshore environment 

of concern is shoreward of the 10-m isobath in the Beaufort and Chukchi Seas and shoreward of 

the 20-m isobath in the Hope and Norton Basins. 

5.1. DIRECT EXPOSURE 

There is no known direct exposure pathway to humans from the discharges associated with oil 

and gas exploration. 

5.2. CONSUMPTION OF EXPOSED AQUATIC SPECIES 

Ingestion of organisms that have accumulated significant concentrations of heavy metals from 

drilling fluids and cuttings is the potential principal source of adverse human health effects 

caused by discharge of drilling fluids and cuttings into the marine environment. Certain metals, 

like lead and cadmium, can be quite toxic to mammals if eaten in sufficiently large amounts, but 

neither the Food and Drug Administration (FDA) nor the USEPA has set maximum levels of 

these chemicals in fish and shellfish slated for human consumption, with the exception of 

methylmercury. This evaluation only considers the potential effects to humans from 

consumption of aquatic life likely to be exposed to discharges from oil and gas exploration 

facilities authorized by this permit. 

The Area of Coverage is characterized by a food web in which the zooplankton and epifauna 

(mysid shrimp, copepods, amphipods, euphasiids, etc.) comprise the major food resource of 

birds, marine mammals, and fishes in the area. Fishes are a food source for birds, and some 

fishes and marine mammals. Humans consume shellfish, fishes, some birds, and marine 

mammals. 

5.2.1. Subsistence Consumption 

Subsistence harvests occur year-round, with different species being emphasized during different 

seasons. Due to the migratory and seasonal nature of subsistence resources for consumption, the 

period of their peak availability is often very brief and localized. Therefore, the annual harvest 
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and consumption of species closely reflects the timing and specific mix of locally available 

resources that varies by region (Beaufort Sea, Chukchi Sea, Hope Basin, or Norton Basin) and 

local communities within the Area of Coverage. Since the pattern of resource availability is so 

unstable and the harvest success for individual families and villages is so variable, communities 

in Arctic Alaska have adapted to form a highly complex, diverse, and flexible pattern of 

subsistence activity that continually adapts to harvest opportunities. Extensive sharing and trade 

of subsistence harvests among families and between villages further complicates the subsistence 

consumption patterns. 

A description of subsistence-harvest patterns and potential areas impacted by exploratory drilling 

in the Beaufort Sea is provided in MMS (2003) and ADNR (1999). The subsistence areas and 

activities of Wainwright, Barrow, Atqasuk, Nuiqsut, and Kaktovik are expected to be affected, at 

least indirectly, by drilling discharges in the Beaufort Sea. 

A description of subsistence-harvest patterns for each community and potential areas impacted 

by exploratory drilling in the Chukchi Sea is provided in MMS (1991). The subsistence areas 

and activities of Wainwright, Barrow, Atqasuk, Nuiqsut, Point Lay and Point Hope are expected 

to be affected, at least indirectly, by drilling discharges in the Chukchi Sea. Point Lay and Point 

Hope communities rely extensively on resources harvested within or adjacent to the Chukchi 

Sea. 

A description of subsistence-harvest patterns for each community and potential areas impacted 

by exploratory drilling in the Norton Basin is provided in MMS (1982). The Yukon-Kuskokwim 

River Delta in the Norton Basin is critical to the Alaska Native Tribes’ subsistence harvest; 50-

75% of Norton Sound Village diet is by acquisition of marine resources (MMS, 1982). The 

subsistence areas of Kingikmiut, Kauwarak, Unaligmiut, and Ikogmiut are expected to be 

affected, at least indirectly, by drilling discharges in the Norton Basin. These include the 

contemporary communities of Shishmaref, Brevig Mission, Teller, Mary’s Igloo, Whales, Inalik 

(Little Diomede), King Island, Gambell, Savoonga (St. Lawrence Island), Solomon, Golovin, 

White Mountain, Council, Elim, Koyuk, Shaktoolik, Unalakleet, St. Michel, Stebbins, Kotlik, 

Bill Moore’s Slough, Hamilton, Emmonak, Alakanuk, and Sheldon Point. 

A description of subsistence-harvest patterns for each community and potential areas impacted in 

the Hope Basin is provided in USEPA (1984). The subsistence areas and activities of Kivalina, 

Naotak are expected to be affected, at least indirectly, by drilling discharges in the Hope Basin. 

The communities of Kotzebue, Ambler, Buckland, Deering, Kiana, Kobuk, Noorvik, Seawik, 

and Shungnak may also be affected, to a lesser extent, by drilling discharges. 

5.2.1.1. Fishes 

Marine fishes are seasonally important to subsistence communities. The relative importance of 

fisheries to the annual subsistence harvest varies between communities depending on the 
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availability of other food resources. Harvested species depend upon the region (Beaufort Sea, 

Chukchi Sea, Hope Basin, or Norton Basin) and local communities in the Area of Coverage. 

Harvested species in the Beaufort Sea include chum and pink salmon, char cod, smelt, burbot, 

Arctic char, arctic cisco, least cisco, grayling, capelin, sculpin and whitefish. Fishes comprise 

34% of the Nuiqsut subsistence harvest, 13% of the Kaktovik subsistence harvest, and 14% of 

the Barrow subsistence harvest (ADNR, 1999). 

Harvested species in the Chukchi Sea include pink, coho, and chum salmon, arctic char, 

whitefish, grayling, tomcod, flounder, least cisco, burbot, sculpin, smelt, and cod. Fishes 

comprise 10.3% of the Wainwright meat consumption, 14.9% of the Barrow meat consumption, 

20.7% of the Nuiqsut meat consumption, and 32.4 % of the Point Hope meat consumption 

(MMS, 1991). No data were available for Point Lay and Atqasuk (MMS, 1991). 

Harvested species in the Norton Basin include five North American salmon (pink, chum, 

chinook, coho, and king), herring, smelt, saffron cod, whitefish, grayling, arctic char, tomcod, 

flounder, pike, sheefish, blackfish, halibut, and sculpin. The consumption of all fish species for 

individual communities is not known; salmon comprise 30-40% of Norton Sound Village diet. 

Harvested species in the Hope Basin are Arctic char, chum salmon, sheefish, whitefish, tomcod, 

and smelt. Fishes comprise 38.3% of the Kivalina subsistence resources harvested and 45.6% of 

the Naotak subsistence resources harvested (USEPA, 1984). Species specific consumption data 

for other communities located in the Hope Basin is not available. 

5.2.1.2. Marine Mammals 

Marine mammals supply a substantial proportion of the edible resources harvested by 

subsistence communities. The native populations are opportunistic hunters. This tendency, 

along with natural variability in mammal abundances, leads to variability in the number of 

individuals taken each year. 

The majority of the marine mammals harvested in the Beaufort and Chukchi Seas occur in the 

Chukchi Sea, except for bowhead whales, which are also harvested east of Barrow during the 

fall, and polar bears. Species of major importance to subsistence harvests are the bowhead and 

beluga whales; bearded, ringed, hair and spotted seals; walrus; and polar bear. Bowheads are 

unavailable to the people of Point Lay (MMS, 1991) because they migrate too far from shore; 

thus, in Point Lay, the beluga whale is harvested. Seals are a preferred food to all communities. 

Seal oil, from hair and bearded seals, is an important staple and a necessary complement to other 

subsistence foods. In spite of the walrus’ increasing population, the importance of walrus for 

human consumption has been decreasing (MMS, 1991). The harvest of polar bears has remained 

relatively constant since 1980. Approximately 85 animals have been taken annually by residents 

of the Chukchi and Bering Seas (USFWS, 1993). 
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The bowhead whale comprises 20.7% of the Wainwright meat consumption, 10.4% of the 

Barrow meat consumption, and 17.6% of the Point Hope meat consumption; walrus comprises 

4.5% of the Barrow meat consumption and 2.9% of the Point Hope meat consumption; bearded 

seals comprised 6.9% of the Wainwright meat consumption, 1.5% of the Barrow meat 

consumption, 3.4% of the Nuiqsut meat consumption and 11.8% of the Point Hope meat 

consumption; and other seals comprised 5.9% of the Point Hope meat consumption (MMS, 

1991). No data were available for Point Lay and Atquasuk (MMS, 1991). 

Harvested species in the Norton Basin includes bearded, spotted, and ringed seals; bowhead, 

gray, beluga, and minke whales; walrus; and sea lions. Marine mammals comprise 15-20% of 

the Norton Sound Village diet (MMS, 1982). 

Harvested species in the Hope Basin bearded, spotted, and ringed seals; and beluga and bowhead 

whales. Marine mammals comprise 42.3% of the Kivalina subsistence harvest and 5.8% of the 

Noatak subsistence harvest (USEPA, 1984). No consumption data is available for other 

communities located in the Hope Basin. 

5.2.1.3. Coastal and Marine Birds 

Migratory birds and eggs are harvested in the spring and early summer and are important sources 

of food at a time when fresh meat is not readily available. Birds are particularly important to the 

whaling camps even though they are harvested incidentally to other subsistence activities. 

Migratory waterfowl and their eggs are an important source of food for all Yukon Delta fishing 

villages. 

Harvested species in the Beaufort and Chukchi Sea include ducks, geese, brant, ptarmigan, 

oldsquaw, sandhill crane, tundra swan, and eiders. Migratory waterfowl species are harvested in 

the Hope and Norton Basins. Birds comprise 2.9% of the Point Hope meat consumption and 

1.5% of the Barrow meat consumption. No consumption data were available for other Arctic 

communities. 

5.2.1.4. Shellfish 

Crab, clams, and mussels are harvested by the communities of Shaktoolik, Unalakleet, Nome, 

Golovin, Elim, and White Mountain. Shellfish consumption data is not available for these 

communities. 

5.2.2. Effects Analysis 

Some impacts may be measurable, but their effects may be minimal and/or short-term in 

duration; therefore, they may not require avoidance or mitigation. Adverse impacts that are 
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reduced by mitigation below the “significance thresholds” that are incorporated into the permit, 

or that are demonstrated to be acceptable because the risk of the impact occurring is small, are 

considered “nonsignificant.” For this evaluation, “significance threshold” is defined as the level 

of effect that equals or exceeds the adverse changes in subsistence harvest patterns such that one 

or more important subsistence resources would become unavailable, undesirable for use, or 

available only in greatly reduced numbers for a period of 1-2 years. 

Several fishes and marine mammals harvested for subsistence are benthic feeders. Exploratory 

drilling is more likely to have a negative impact on animals associated with the ocean bottom. 

Therefore, special attention should be given to these animals when evaluating the effects of 

drilling discharges. Exploratory operations within nearshore waters have a higher likelihood of 

adverse impacts to fisheries, although overall the impact is expected to be minimal. Mammal 

subsistence harvesting may be affected to the extent that discharge sites may alter the distribution 

of the animals; however, effects should be insignificant if discharge locations are not in close 

proximity to each other. The likelihood of significant metal uptake or transference to humans is 

small due to the limited number of expected discharges, their limited areal extent, and the 

mobility of potentially exposed species. Residues of pollutants accumulated in the marine biota 

are not expected to pose a significant hazard to people. 

Overall, significant impacts to human health are not expected to result from the limited 

discharges of drilling mud that characterize the exploratory phase in the Arctic lease sales. The 

hazard associated with consuming fish and shellfish contaminated with metals or petroleum 

hydrocarbons is expected to be low. The reasons for this assessment are: bioconcentration 

factors for heavy metals other than methylmercury and for mobile aromatic hydrocarbons such 

as benzene are too low to warrant concern about biomagnification; mercury, which is potentially 

the most hazardous metal, is a relatively minor constituent of drilling muds; and the areas 

affected by exploratory drilling discharges are too small to contribute substantially to the diet of 

fish or shellfish harvested by fisheries. 

The Norton Sound environment is currently in a pristine state with no major industry and a local 

population of only 12,000 (OCSEAP as cited in MMS, 1982). Disruption of the natural 

environment may have sociological as well as environmental impacts; the natives of this area 

depend on the migrating mammals, native fisheries, and seasonal bird populations for a 

subsistence harvest. Some of the potential impacts from offshore oil and gas discharges include 

adverse effects to the benthic biota from platform discharges, possible disruption of migratory 

patterns of marine mammals, and interference with the subsistence harvest of the natives. 
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6.0 TRIBAL RESOURCES 

Tribal resources are utilized for much more than just nutrition. Tribal resources include those 

resources used for direct personal or family use (e.g., food, shelter, fuel, clothing, tools, or 

transportation) and the making and selling of handicraft articles. Subsistence in Alaska is more 

than harvesting, gathering, processing, sharing, and trading; it also includes cultural, social, and 

economic values associated with the taking, use, and exchange of these resources. Subsistence 

embodies the essence of Inupiat culture. The values these resources hold and the importance 

Native Alaskans place on sharing with family and village, and in continuing as a harmonious part 

of the ecosystem of which they are a part, is paramount. 

Language, culture, spiritual beliefs, customs, and respect for others and for oneself, are all tied 

into an integrated, holistic view of the world centered on the traditional hunting, fishing, and 

gathering way of life associated with local resources. The collection, processing, and 

distribution of subsistence resources nearly always involve some group activity; the cultural 

value placed on kinship and family relationships is apparent in the sharing, cooperation, and 

subsistence activities that occur in their society. The continued opportunity to engage in 

subsistence uses is a fundamental component of all Alaska Native cultures and serves as the 

keystone to social, ethnic and psychological identity. Therefore, the loss of any subsistence 

resource could greatly impact the social structure of these communities. 

The Inupiat in the Arctic depend on subsistence taking of shellfish, fish, marine mammals, birds, 

and whales for subsistence. Many marine species are the basis of an elaborate food distribution 

system and has enormous cultural significance for all communities. Bowhead whaling also 

remains at the center of Inupiat spiritual and emotional life; it embodies the values of sharing, 

association, leadership, kinship, arctic survival, and hunting prowess. Because they migrate too 

far from shore, bowheads are unavailable to the people of Point Lay (MMS, 1991). In Point Lay, 

a communal hunt of the beluga whale serves many of the same economic and social purposes 

that bowhead whaling does for other North Slope communities. Open skinboat (umiak) hunting 

of the Pacific walrus is economically and culturally the most important subsistence activity for 

the communities of Little Diomede, King Island, Gambell, Savoonga and Whales. Salmon is the 

most important cash resource for communities in the Norton Basin; 70-85 percent of income is 

from salmon fishing (Ellanna as cited in MMS, 1982). Besides providing meat for food and 

skins for clothing, waterfowl have always been deeply involved in Native folklore and 

mythology (Davidson as cited in MMS, 1982). Herring are a primary source of cash for the 

communities of St. Michael and Stebbins. 

Many non-edible parts of the animals harvested are used to make both functional items as well as 

arts and crafts. Marine mammal bones and hides are used to construct temporary shelters and 

traditional boats. Seal skins and gut are used for clothing and other mohme uses, as well as 

crafts. Seal skin, particularly that of the bearded seal, is also used to cover the whaling boats and 

carrying water. Whale baleen is decorated and etched into story-telling art works and baskets. 

Whale bones are carved into miniature animals, umiaks, and hunting scenes, or made into 
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functional items such as knife or ulu handles and needle cases. Walrus cowhides are the only 

suitable hide for covering the skinboat (umiak) and bull walrus are highly prized for their ivory. 

Walrus meat is traditionally used, particularly in Point Lay, for dog food. Bearded seal whiskers 

are used in making earrings. Polar bear and seal fur are used to make parkas, slippers, mukluks, 

hats, dolls, and Eskimo yo-yos. Bird beaks, bones, and feathers adorn ceremonial drss and 

masks. Animal and bird skins are used to make drums and many other craft items, such as spirit 

masks. 

Any activity that has the potential to harm marine resources has the potential to affect tribal 

resources. Oil and gas exploration discharges have the potential to cause avoidance behavior or 

loss of supporting habitat for tribal resources in the marine environment. This would result in 

the potential reduction in local fish and marine mammal populations, increased travel distance 

and hunting time required to harvest resources, potential reductions in harvest success rates, and 

increased competition for nearby subsistence resources. The following examples illustrate the 

sensitivity of Arctic communities to Western influence: The community of Teller has already 

shown decreased subsistence dependence and perhaps loss of subsistence knowledge due to a 

long history of contact with other commercial activities (e.g., mining, reindeer herding); and The 

increased use of aluminum boats, rather than umiaks, for walrus hunting has introduced some 

social changes associated with the hunt and its distribution. Consequently, the impacts from oil 

and gas exploration activities, themselves, are likely to have far more adverse impacts to tribal 

resources than the discharges associated with those activities.
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7.0 RECREATIONAL AND COMMERCIAL FISHERIES 

This section describes the recreational and commercial fisheries in the Area of Coverage and the 

potential impacts exploratory drilling discharges may have on these activities. Two major 

determinations of whether a fishery is viable are the abundance and biomass of the target species. 

Fish biomass and diversity in both the Beaufort and Chukchi Seas are relatively low. The 

abundance and biomass for epibenthic invertebrates appears to be low as well, based on limitedscale bottom trawl survey efforts in the Beaufort and Chukchi Seas (Morris, 1981). 

7.1. COMMERCIAL HARVESTS 

The potential for commercial fisheries in Arctic waters is probably limited to nearshore, 

localized, small-scale efforts. Additional information on commercial harvests is provided in 

Section 4.8. 

No commercial fishery is currently operating within the boundaries of the Beaufort Sea. The 

only continuous commercial fishery operations on the Alaska North Slope occur during the 

summer and fall months in the Colville River Delta, adjacent to the Beaufort Sea Area of 

Coverage (MMS, 2002). The Colville River delta fisheries include two commercial enterprises. 

Arctic cisco is the most important resources harvested. This species, along with broad and 

humpback whitefish, are marketed for human consumption. Least cisco is sold for dog food 

(MMS, 1990). The harvest of Arctic and least cisco varies considerably from year-to-year due to 

variability in juvenile recruitment, and unpredictable physical factors such as the distribution of 

saline water in the delta (Moulton et al., 1992). 

Aside from a relatively small chum salmon fishery in Kotzebue Sound, there are no commercial 

fisheries in the Chukchi Sea Area of Coverage (MMS, 2002). Among the most abundant species 

in the Chukchi Sea, the majority is not commercially valuable (e.g., sculpins and eelpouts). 

Trawl survey results for the Chukchi Sea do not indicate any potential for commercial harvest 

(Morris, 1981). 

Important commercial fisheries in Norton Sound include five North American salmon (pink, 

chum, chinook, coho, and king), Pacific herring, and king crab (MMS, 1982). The fishery is 

relatively small and localized. Although commercial harvests in the Norton Sound area are low 

in volume and value compared to other areas of Alaska, the economic returns from fish 

harvesting have benefited virtually every family in the smaller communities which circle Norton 

Sound (MMS, 1982). 

7.2. RECREATIONAL HARVESTS 

For the purpose of this evaluation, recreational harvests are those conducted by non-residents of 

the region. The recreational opportunities in the Area of Coverage are somewhat limited 

compared to other areas of the state due to the restricted and costly access, the lack of support 
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facilities, and the harsh weather conditions. Non-resident participation is often limited to 

professionally-guided fishing trips for Arctic char, grayling, and salmon. 

7.3. EFFECTS OF DRILLING DISCHARGES ON HARVEST QUANTITY 

Disposal of drilling muds via any discharge technique is not expected to directly interfere with 

commercial fish harvests. 

7.4. EFFECTS OF DRILLING DISCHARGES ON HARVEST QUALITY 

The exploratory drilling discharges are not expected to significantly impact the quality of the 

commercial fish harvest. 

7.5. SUMMARY 

Nearshore locations used for commercial fisheries are predominantly outside areas that could 

conceivably be impacted by activities conducted during Beaufort Sea and Chukchi Sea 

exploratory drilling discharges. Exploratory discharges within state waters have a higher 

likelihood of adverse impacts to fisheries, although overall the impact is expected to be minimal. 
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8.0 COASTAL ZONE MANAGEMENT 

8.1. REQUIREMENTS OF COASTAL ZONE MANAGEMENT ACT 

The Coastal Zone Management Act requires that states make consistency determinations for any 

federally licensed or permitted activity affecting the coastal zone of a state with an approved 

Coastal Zone Management Program (CZMP) (16 USC Sec. 1456(c)(A) Subpart D). Under the 

Act, applicants for federal licenses and permits must submit a certification that the proposed 

activity complies with the state’s approved CZMP. The state then has the responsibility to either 

concur with or object to the consistency determination. For general NPDES permits, USEPA is 

considered an applicant submitting the general permit to the state for a consistency 

determination. 

Consistency certifications are required to include the following information (15 CFR 930.58): 

• A detailed description of the proposed activity and its associated facilities; 

• A brief assessment relating the probable coastal zone effects of the proposal and its 

associated facilities to relevant elements of the CZMP; 

• A brief set of findings indicating that the proposed activity, its associated facilities, and 

their effects are consistent with relevant provisions of the CZMP; and 

• Any other information required by the state. 

Consistency determinations are required if a federally licensed or permitted activity “affects” the 

coastal zone. Discharges of drilling muds and cuttings during exploration oil and gas activities 

in the Area of Coverage are expected to occur in the adjacent state waters, therefore, a 

consistency assessment is required. The enclosed certification statement is based upon the 

requirements listed in 15 CFR Part 930.39 and the Alaska Division of Governmental 

Coordination's "Guide to Preparing an ACMP Consistency Determination for Federal 

Activities." 

8.2. AGENCY INFORMATION 

Agency: USEPA 

District or Region: Region 10 

Agency Contact: Kristine Koch 

Phone: (206) 553-6705 

Fax Number: (206) 553-0165 

Address: 1200 6th Avenue, M/S OWW-130, Seattle, WA 98101 

Electronic Mail: koch.kristine@epa.gov 
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8.3. PROJECT INFORMATION 

The proposed reassurance of the Arctic General Permit (GP) would authorize the following 

discharges from exploratory offshore oil and gas operations in the coverage area corresponding 

with MMS OCS regions of the Beaufort and Chukchi Seas, Hope and Norton Basins, and state of 

Alaska waters contiguous to the landward boundary of these MMS OCS regions. Discharges 

from exploratory offshore oil and gas operations include: drilling mud and drilling cuttings; 

deck drainage; sanitary wastes; domestic wastes; desalination unit wastes; blowout preventer 

fluid; boiler blowdown; fire control system test water; non-contact cooling water; 

uncontaminated ballast water; uncontaminated bilge water; excess cement slurry; mud, cuttings, 

and cement at the seafloor; and test fluids. A map of the coverage area is provided in Figure 1-1. 

8.4. PROJECT DESCRIPTION 

8.4.1. Detailed Description 

The proposed reassurance of this GP is to continue permit coverage that had been authorized 

under the previous permit. The discharges are described in further detail in Section 2.0. 

Changes made to the GP include more stringent applicability and notification requirements, new 

requirements for all discharges, inclusion of new federal effluent guidelines for the discharge of 

drilling fluids and drilling cuttings (discharge 001), new requirements for submittal of 

information to discharge from more than five wells (discharge 001), more stringent requirements 

for the discharge of sanitary wastes (discharge 003), requirements for a quality assurance plan, 

updated requirements for a best management practices plan, and update of standard conditions to 

reflect the federal regulations. 

8.4.2. Timeline 

The proposed GP would be effective for a five year term that would commence after the public 

review process, the development of a response to comments, and the final permit issuance. In 

addition, the provisions of the GP may be administratively extended beyond the five year term 

for covered facilities that timely reapply until EPA reissues the GP. 

8.4.3. Site Plan 

An applicant is required to submit a map of the coverage area with the Notice of Intent to be 

authorized under this GP if they are requesting a mobile discharge authorization. 
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8.4.4. Supporting Documentation 

Please refer to the proposed GP in Appendix C, Fact Sheet for the GP in Appendix E, and other 

sections of this ODCE. 

8.4.5. Proposed Best Management Practices 

Permittees are required to develop and implement a BMP Plan. This requirement can be found 

in Permit Part IV.B of the GP (Appendix C). 

8.5. PROJECT LOCATION 

Figure 1-1 depicts the geographic area covered by the proposed GP. This geographic area covers 

the area of federal waters of the U.S. located in the Beaufort Sea, Chukchi Sea, Hope Basin, and 

Northern Norton Basin seaward of the State water boundary from Point Hope to the Alaska, 

USA and Yukon, Canada border and to all State waters contiguous to the Beaufort Sea, Chukchi 

Sea, Hope Basin, and Norton Basin Minerals Management Service planning areas. The proposed 

GP would authorize qualifying discharges into waters of the U.S. located in the coverage area. 

8.6. CONSISTENCY WITH THE ENFORCEABLE POLICIES OF THE ALASKA 

COASTAL MANAGEMENT PROGRAM 

8.6.1. District Policies 

A final consistency determination on the current GP was made on November 29, 1994 (State I.D. 

No. AK9409-03PA). Additional comments on the proposed GP's consistency with the District 

CMPs will be solicited from the affected coastal districts by Department of Natural Resources, 

Office of Project Management and Permitting, Alaska Coastal Zone Management during the 

review period following this Federal agency notification (15 CFR Part 930.41). 

8.6.2. Alaska Coastal Management Program Standards 

The following analysis addresses the consistency of the proposed action with the relevant ACMP 

standards. 

6 AAC 80.040: Coastal Development 

The proposed GP would authorize qualifying discharges into marine waters (saltwater). The 

activity is water-dependent. 
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6 AAC 80.060: Recreational Use, 

6 AAC 80.080: Transportation and Utilities, and 

6 AAC 80.120: Subsistence 

The proposed GP authorizes wastewater discharges from several types of facilities. Nothing in 

this permit grants the right to build a facility contrary to the local, state and federal laws 

applicable to the coverage area. 

6 AAC 80.130: Habitats 

POTENTIAL IMPACTS

The problems that are anticipated to arise should be remedied by instituting a BMP Plan 

attempting to foresee and plan to alleviate any potential impacts. The fact sheet and proposed 

GP contain general situations which must be addressed in the BMP Plan. More site-specific 

issues will be addressed as appropriate. 

GENERAL PERMIT PROVISIONS

Effluent Limitations. Permit Parts II.A, through II.N contain effluent limitations restricting the 

discharge of pollutants. Please see the proposed GP (Appendix C) and fact sheet (Appendix E) 

for a full description of the effluent limitations for each type of discharge. It is anticipated that 

ADEC will certify mixing zone provisions into the GP to allow for a site specific evaluation 

before authorizing a mixing zone for domestic wastewaters. These provisions are contained in 

the proposed permit. 

Best Management Practices. Part IV.B of the permit includes the requirement for a BMP plan in 

order to minimize adverse environmental effects from activities authorized by the GP. 

 

OFFSHORE AREAS 

The proposed GP would authorize the discharge of domestic wastewater, construction 

dewatering, discharges of hydrostatic test waters, storm water and discharges from mobile 

response units to the marine environment. The GP contains proposed effluent limitations for 

each category of discharger and requires that a BMP Plan be developed, as described above. 

WETLANDS

Discharges of wastewaters to tundra wetlands are not authorized under this proposed GP. 

RIVERS, STREAMS, AND LAKES

Discharges of wastewaters to rivers, streams and lakes are not authorized by this proposed GP. 
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6 AAC 80.140. Air, Land, and Water Quality 

AIR QUALITY STANDARDS

The proposed GP would regulate discharges into waters of the United States. Under the NPDES 

program, EPA does not have jurisdiction over activities affecting air quality. 

WATER QUALITY STANDARDS

Section 301 of the CWA prohibits the discharge of pollutants to waters of the United States 

unless that discharge complies with technology-based effluent limitations or any more stringent 

limitation necessary to achieve state water quality standards. Section 402 of the Act authorizes 

EPA to issue NPDES permits with conditions necessary to ensure that a discharge complies with 

the requirements of the CWA. 

The proposed GP would include effluent limitations, best management practices, and monitoring 

and reporting requirements to ensure that authorized discharges comply with the Alaska Water 

Quality Standards (AWQS). 

Effluent Limitations. The proposed effluent limitations incorporate specific AWQS for 

parameters applicable to each category of discharge. It is anticipated that the ADEC will certify 

mixing zone provisions into the GP. If this does not occur, no mixing zone provisions for the 

proposed discharge will appear in the final GP. 

 

Best Management Practices. Part IV.B of the GP includes a requirement to develop and 

implement a BMP Plan in order to ensure compliance with the AWQS for discharges authorized 

under this permit. 

Monitoring and Reporting Requirements. The GP requires monitoring for compliance with the 

effluent limitations listed in the permit. 

LAND QUALITY STANDARDS

The proposed GP would regulate discharges into waters of the United States. Under the NPDES 

program, EPA does not have jurisdiction over upland activities which do not involve a discharge 

to the waters of the United States. 

6 AAC 80.150: Historical, Prehistoric, and Archeological Resources 

It is unlikely that discharges authorized under this GP would affect historical, prehistoric, and 

archaeological resources. However, the discharge of dredged or fill material associated with the 

construction of the facilities may affect these resources. The state would have an opportunity to 

identify these resources during the ACMP review for the required Section 404 permit. 
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8.7. CONSISTENCY DETERMINATION 

15 CFR Part 930.37. Consistency Determinations for Proposed Activities 

Based on the above analysis of the state and district CMPs, EPA believes that the proposed 

general NPDES permit for Facilities related to Oil and Gas Production located off-shore of 

Alaska in the Beaufort and Chuckchi Seas is consistent to the maximum extent practicable with 

approved State management programs. 

The EPA determines that the proposed activity complies with, and will be conducted in a manner 

consistent to the maximum extent practicable with, the ACMP, including affected coastal district 

programs. 
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9.0 MARINE WATER QUALITY CRITERIA 

The 403(c) regulations of the CWA allow a 100-m (328-ft) radius mixing zone for initial dilution 

of discharges. At the edge of the mixing zone, marine water quality criteria must be met. 

Compliance with water quality criteria at the edge of any authorized mixing zone for drilling 

muds and cuttings under this permit is assessed in this section. 

Marine water quality criteria for the protection of aquatic life (45 FR 79318, 50 FR 30784, 51 FR 

43665, and 52 FR 6213) are stated as acute (a 1-hour (h) or 24-h average concentration not to be 

exceeded more than once every three years on average) and chronic (a 96-h average 

concentration not to be exceeded more than once every three years on average) criteria, and riskbased marine water concentration criteria are stated for protection of humans due to consumption 

of marine fish (CMF) (assuming a 10-6 risk level and an average lifetime consumption of 6.5 

grams per day (g/day) of contaminated fish and/or shellfish for a 70 kg male) (USEPA, 1986). 

The chronic and CMF criteria are applicable to relatively continuous discharges that expose 

organisms in their vicinity to a relatively constant flux of pollutants. Acute criteria values are 

applicable to instantaneous releases or short-term discharges of pollutants. 

9.1. TRACE METALS 

The four methods of sample preparation for metals analysis that have been recognized by EPA 

include 1) total metals, 2) total recoverable metals, 3) acid soluble metals, and 4) dissolved 

metals. The first three of these methods measure metals that are dissolved in water, along with 

metals that become dissolved when samples are refluxed in acid. The severity of the extraction 

procedures decreases in the order: total metals > total recoverable metals > acid soluble metals 

method. Dissolved metals are operationally defined as those that pass through a 0.45 μm poresize filter at the time of collection. 

Historically, federally recommended water quality criteria for metals in marine waters were 

stated in terms of acid soluble concentrations of trace metals, which until recently was believed 

by EPA to be the “scientifically correct” basis upon which to establish water quality criteria for 

trace metals (USEPA, 1986). Recently, however, EPA has re-evaluated the use of metals criteria 

in water quality standards extended to protect aquatic life (USEPA, 2002). This guidance 

supersedes past criteria document statements expressing criteria in terms of the dissolved metal. 

The new EPA guidance (USEPA, 2002) recommends using dissolved metals because they more 

accurately reflect the bioavailable fraction, and hence the potential toxicity of a metal. The state 

of Alaska has adopted these criteria for protection of state waters in Title 18, Chapter 70 of the 

Alaska Administrative Code (18 AAC 70). EPA also uses these criteria to ensure protection of 

federal waters. 
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9.1.1. Drilling Fluids 

Evaluation of water quality compliance for the discharge of drilling muds during exploratory oil 

and gas drilling in previous ODCEs has relied on measurements of metals concentrations 

performed on generic drilling muds. Metal concentrations were reported as “whole mud 

concentrations,” which were assumed to be equivalent to values obtained using the total metals 

method. Previous ODCEs have also assessed compliance with water quality criteria using 

estimates of dissolved metal concentrations. This approach has been justified because 

exploratory drilling discharges are intermittent, diluted rapidly, and quickly deposited on the 

ocean floor in the vicinity of the discharge. Toxicity from dissolved metals are thought to be of 

primary concern, as organisms are exposed to dissolved metals via uptake of water through gills, 

skin, or cell walls. 

Determination of compliance with Alaska’s current marine criteria for metals requires that the 

dissolved metal fraction of the whole mud be used to determine compliance with water quality 

criteria. Since there are little data pertaining to the partitioning of metals between dissolved and 

particulate phases of drilling fluids, previous ODCEs have assumed that partitioning of metals 

between dissolved and solid phases in drilling muds are similar to that measured for dredged 

material. Previous ODCEs have also used a ratio of 0.001 as a conservative estimate of the 

partitioning between dissolved and solid phases for all metals when evaluating compliance with 

water quality criteria. However, Avanti Corporation (1993) provided measured trace metal leach 

percentages from barite and drilling fluids, which provides for a more accurate analysis of this 

discharge. Table 9-1 provides the mean and maximum trace metal leach factors (leach 

percentages divided by 100) reported in Avanti Corporation (1993). 

Since there are currently no dissolved fraction data for whole muds in the Alaskan marine 

environment, the values in Table 9-1 were used to evaluate the metals concentrations in the water 

column and at the edge of a 100-m mixing zone. First, the total metals concentration in the 

drilling fluid (Table 2-2) was used to determine which metals in drilling fluids have the potential 

to be problematic (Case Study I). Then the maximum and mean leach factors in Table 9-1 were 

used to convert the total metals concentrations in the drilling fluid to water column 

concentrations (Case Studies II and III, respectively). Tables 9-3 through 9-5 show the 

maximum predicted dissolved metal (arsenic, barium cadmium, chromium, copper, iron, lead, 

mercury, nickel, and zinc) concentrations for each case study at the edge of the mixing zone due 

to the discharge of Alaskan drilling muds in water depths of 40, 20, and 5 m in both open water 

and below ice. The predicted dissolved metal concentration is based on the maximum reported 

drilling mud total metal concentration, the assumed partition coefficient, and the dilution factors 

predicted by the OOC model for each discharge scenario (e.g., open-water discharge in 20-m 

water depth) available in Tables 3-5 and 3-7. The predicted dissolved metal concentration were 

compared directly to the marine water quality criteria, also presented in Tables 9-3 through 9-5. 

The results of Case Study I (Table 9-3) show that chromium, copper, lead, and zinc are 

potentially problematic (i.e., may exceed water quality criteria at the edge of the mixing zone). 
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(It should be noted that for chromium, the total chromium concentration in the mud was assumed 

to be chromium VI since this is the Alaska water quality criteria but there is no data for the 

chromium VI concentration in drilling. This would provide an overestimate of the chromium VI 

concentration in the water column due to the drilling fluid.) However, Case Studies II and III 

show that all dissolved metal concentrations are less than their respective water quality criteria at 

the edge of the mixing zone boundary. Thus, EPA concludes that there are unlikely to be any 

exceedances of water quality criteria for any metals based on the predicted dilutions obtained 

from the OOC model runs. However, more information should be obtained to show partitioning 

of metals from the discharge of whole muds used in Alaska for future analysis. 

9.1.2. Drilling Cuttings 

Determination of compliance with Alaska’s current marine criteria for metals requires that the 

dissolved metal fraction of the drilling cuttings be used to determine compliance with water 

quality criteria. Since there are little data pertaining to the partitioning of metals between 

dissolved and particulate phases of drilling muds and cuttings, this ODCE assumes that 

partitioning of metals between dissolved and solid phases in drilling cuttings are similar to that 

measured for dredged material. This is believed to be a reasonable assumption because of the 

physical similarity of the two materials. Dredged materials are naturally occurring sediments 

frequently containing elevated concentrations of contaminants, with variable proportions of sand, 

silt, and clay particles, and containing up to 80 percent water. Table 9-2 provides soluble and 

solids metals concentrations for dredged materials dumped at sea and partitioning of metals in 

Arctic Rivers and the Coastal Beaufort Sea. 

Since there are currently no dissolved fraction data for drilling cuttings in the Alaskan marine 

environment, dissolved metal concentrations were evaluated under three case analyses: (1) that 

the all the metals in the drilled cuttings will dissolve in the water column; (2) that the dissolved 

metals fraction is two orders of magnitude lower than that of the drilled cuttings; and (3) that the 

metals in the drilled cuttings will partition similar to that of dredge material dumped at sea. The 

first case will grossly over-estimate the potential effects since metals in solids will not fully 

dissolve in the marine environment; however, this does provide a worst-case estimate. The 

second case was based on EPA’s knowledge of how metals patrician in marine waters (i.e., 

drilled cuttings are one to two orders of magnitude higher than those in the suspended particulate 

phase, which in turn are one to two orders of magnitude higher than those in the liquid phase) 

(USEPA, 1985, 1993a, 2000a). The third case is based on the physical similarity of drilled 

cuttings and dredged materials. 

Tables 9-6 through 9-8 show the maximum predicted dissolved metal (arsenic, cadmium, 

chromium, copper, lead, mercury, and zinc) concentrations for each case study at the edge of a 

100-m mixing zone due to the discharge of Alaskan drilling cuttings in water depths of 40, 20, 

and 5 m in both open water and below ice. The predicted dissolved metal concentration is based 

on the maximum reported drilling cuttings total metal concentration (Table 2-4), the assumed 

partition coefficient (Table 9-2), and the dilution factors predicted by the OOC model for each 
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discharge scenario (e.g., open-water discharge in 20-m water depth) available in Tables 3-5 and 

3-7. In general, the calculation was performed as follows: 

 

[Dissolved Metal]MZ = [(Total Metal)EOP (Partition Coefficient)]/ [Dilution Factor] (1)

where: 

 [Dissolved Metal]MZ = the dissolved metal concentration at the edge of the 

 mixing zone in mg/L. 

 [Total Metal]EOP = the drilling mud total metal concentration at the end of 

 the pipe in mg/kg dry weight. 

 [Partition Coefficient]= the most conservative dissolved metal to total metal ratio 

 (in kg/L) – Equals 1.0 in Table 9-6; equals 0.01 in 

 Table 9-7; and equals values in Table 9-2 for Table 9-8. 

 [Dilution Factor] = the OOC model-predicted dilution factor at the edge of 

the mixing zone for each of the modeling cases available 

in Tables 3-5 and 3-7 (unitless). 

 

The predicted dissolved metal concentrations were compared directly to the marine water quality 

criteria, also presented in these tables. Table 9-6 shows that cadmium, copper, lead, mercury, 

nickel and zinc are potentially problematic (i.e., may exceed water quality criteria at the edge of 

the mixing zone). The extent to which these metals partition is evaluated in Tables 9-7 and 9-8. 

These tables show that all dissolved metal concentrations are less than their respective water 

quality criteria at the edge of the mixing zone boundary, except for lead and zinc in Case II 

(Table 9-7) for open water discharges at a depth of 5 m. Historical discharge data from 

discharge monitoring reports show that open water discharges have not occurred in the past. 

Thus, EPA concludes that there are unlikely to be any exceedances of water quality criteria for 

any metals based on the predicted dilutions obtained from the OOC model runs. However, more 

information should be obtained to show partitioning of metals from the discharge of drilling 

cuttings in Alaska for future analysis. 

9.2. ORGANIC COMPOUNDS 

Organic compounds are found in drilling muds and also have the potential to cause marine water 

quality criteria exceedances. Table 2-3 summarizes results from several studies that examined 

organic chemical concentrations in drilling muds and mineral oils, respectively. None of the 

individual compounds that were detected have established marine water quality criteria. More 

organic chemical data are needed to fully assess the potential for organic compounds in 

discharged drilling muds to violate water quality criteria. 
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9.3. TOTAL RESIDUAL CHLORINE 

Total residual chlorine from the disinfection process of the sanitary discharge has the potential to 

cause marine water quality criteria exceedances under certain circumstances. The NPDES 

permit limits are 1.0 mg/L as a maximum daily limit within Alaska State waters with an 

approved mixing zone and in Federal waters. EPA evaluated this limit at the edge of a 100-m 

mixing zone due to the discharge of Alaskan drilling cuttings in water depths of 40, 20, and 5 m 

in both open water and below ice. The dilution factors in Tables 3-5 and 3-7 were used to 

predict the concentrations at the edge of the mixing zone. Table 9-9 provides a summary of this 

analysis. Based on this evaluation, only the 5-m open-water discharge has the potential to 

violate Alaska water quality standards. However, more information (e.g., model verification, 

environmental sampling, effluent sampling) should be obtained to determine whether the 

assumed dilution factors are appropriate for future analysis. 

9.4. SUMMARY 

Trace metals in drilling mud discharges from exploratory oil and gas wells are not expected to 

exceed marine water quality criteria; however, more information regarding how muds and 

cuttings discharged in Alaska partition in the environment is needed to provide a more complete 

analysis. An assessment of the potential for organic compounds to exceed water quality criteria 

was not possible due to a lack of data concerning the concentrations of such materials in drilling 

muds and the lack of applicable water quality criteria for some of the chemicals detected in the 

muds. Total residual chlorine in sanitary discharges is not expected to exceed marine water 

quality criteria; however, the dilution factors and modeling should be verified to ensure that 

water quality standards are met in future analysis. 
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10.0 DETERMINATION OF UNREASONABLE DEGRADATION 

Chapter 1.0 of this ODCE provides the regulatory definition of unreasonable degradation of the 

marine environment (40 CFR 125.121[e]) and indicates the ten criteria which are to be 

considered when making this determination (40 CFR 125.122). The actual determination of 

whether the discharge will cause unreasonable degradation is made by the USEPA Region 10 

Administrator. The intent of this chapter is to briefly summarize information pertinent to the 

determination of unreasonable degradation. 

While the information contained in this ODCE is intended to provide the basis for the 

determination of unreasonable degradation, it should be cautioned that significant gaps exist in 

our understanding of the risk of discharging drilling muds into the marine environment, both 

generally and in the area of coverage. Of particular concern are the long-term chronic and 

sublethal impacts of drilling muds and cuttings on marine biota. In addition, uncertainty exists 

regarding determinations of compliance with federal water quality criteria. To assist in filling 

these data gaps it is recommended that research be conducted to accomplish the following: 

• Develop more laboratory data on sublethal and chronic effects at environmentally 

realistic concentrations. 

• Generate data on the bioaccumulation of specific organisms and the interpretation of the 

significance of bioaccumulation. 

• Conduct field studies to quantify the environmental concentrations of drilling fluids (e.g., 

Parrish and Duke 1990). 

• Determine total recoverable metal concentrations of drilling muds and partition 

coefficients for calculating dissolved metal concentrations under ambient conditions to 

allow an acceptable evaluation of toxicological risk to marine biota that can be used to 

evaluate compliance with water quality standards. 

• Conduct laboratory/field studies to determine the critical amount and rate of sedimentation that will adversely impact benthic communities in Alaskan waters. 

• Identify critical spawning regions for demersal and pelagic fish within the area of 

coverage. 

• Identify locations that include critical substrate used by commercially important 

epibenthic invertebrates. 

10.1. CRITERION 1 

The quantities, composition, and potential for bioaccumulation or persistence of the 

pollutants to be discharged. 

It is estimated that 21 exploration wells and 12 delineation wells will be drilled in the Beaufort 

Sea, 2 exploration wells and 2 delineation wells will be drilling in the Chukchi Sea, and no wells 

will be drilled in the Hope Basin or Norton Sound. Drilling fluids and cuttings will be the 
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primary discharge from exploration facilities; however, several other discharges from support 

activities may occur as well. 

Components of concern in drilling fluids include trace metals and specialty additives used with 

generic and synthetic-based drilling mud systems. Mass loadings of the additives depend on the 

concentrations, frequency of usage, and conditions encountered during drilling. It is estimated 

that 10,345 bbl drilling muds and 58,040 bbl drill cuttings (8,085 bbl drilling muds and 50,160 

bbl drill cuttings in the Beaufort Sea; 2,260 bbl drilling muds and 7,880 bbl drill cuttings in the 

Chukchi Sea) will be discharged in the area of coverage. Drill cuttings tend to settle quickly 

upon discharge and tend to accumulate near the discharge point. Drilling muds tend to be diluted 

rapidly following discharge and are of intermittent and short duration. Modeling and studies 

have shown that the discharge is generally limited to the immediate discharge area (within 100 m 

of the facility). Studies have shown that drilling muds and cuttings from a single well would not 

be detectable in the environment after 1-2 years. 

It is difficult to predict the quantities of discharges from support activities (i.e., sanitary and 

domestic wastes, deck drainage, blowout preventer fluid, desalination unit waste, fire control 

system test water, non-contact cooling water, ballast water, bilge water, boiler blowdown, test 

fluids, excess cement slurry, and mud, cuttings, cement at seafloor) since quantities in the past 

were reported as flow rates and the duration was not reported. The new permit requires 

permittees to report the volumes of these discharges so future analysis can consider the total 

effects. Since these discharges are intermittent and small in volume, they are not a significant 

source of pollutants to the environment. These discharges can include ethylene glycol, 

lubricants, fuels, biocides, surfactants, detergents, corrosion inhibitors, cleaners, solvents, paint 

cleaners, bleach (chlorine), dispersants, coagulants, oil and grease, suspended solids, bacteria, 

cement, cement extenders, and accelerators. These discharges are generally limited to the 

immediate discharge area (within 100 m of the facility). 

Existing data are inadequate for the quantification of potential bioaccumulation from exposure to 

discharges from exploratory oil drilling operations. Available data suggest that the hazard is 

toxicologically insignificant. 

10.2. CRITERION 2 

The potential transport of such pollutants by biological, physical, or chemical 

processes. 

Physical transport includes currents, mixing, settling, and diffusion. Exploratory drilling solids 

deposition and accumulation is generally limited to the immediate discharge area (within 100 m 

of the facility). At present, the area-wide large-scale distribution of drilling discharges is 

difficult to predict; however, it can be surmised that drilling discharges associated with shortterm exploration operations will have little effect on the environment due to deposition of 

drilling-related materials on the seafloor. Drill cuttings will rapidly settle to the seafloor upon 

discharge, where the other discharges will remain in the water column for a longer period of 

time. These discharges tend to be diluted rapidly following discharge; however, dilution is 
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dependent on the density, depth, and current speed of the waterbody. Of the three disposal 

methods available (open-water, above-ice, and below-ice), below-ice disposal is the least 

desirable due to the lesser dilution and dispersion potential for discharges. 

Chemical transport includes the dissolution of substances in seawater, particle flocculation, 

complexing of compounds that may remove them from the water column, redox/ionic changes, 

and adsorption of dissolved pollutants on solids. Chemical transport of drilling fluids and other 

discharges is poorly described. Much must be gleaned from general principles and studies of 

other, related materials. Several broad findings are suggested, but the data for a quantitative 

assessment of their importance are lacking. Chemical transport will most likely arise from 

oxidation/reduction reactions that occur in sediments. Changes in redox potentials will effect the 

speciation and physical distribution (i.e., sorption-desorption reactions) of discharged 

constituents. 

Biological transport includes bioaccumulation in soft or hard tissues, biomagnification, ingestion 

and excretion in fecal pellets, and physical reworking to mix solids into the sediment 

(bioturbation). The most effective way to monitor the biological effects of drilling discharges is 

to take quantitative samples of the benthic infauna (animals that live on the sea floor). 

Biological transport of drilling discharges is poorly described and the information must be 

gathered from general principles and studies of other, related materials. Several broad findings 

are suggested, but the data for a quantitative assessment of their importance are lacking. 

Bioaccumulation of a number of metals from exposure to muds and mud components has been 

demonstrated in the laboratory and in the field. Short-term laboratory experiments and field 

exposures indicate that tissue enrichment factors were generally less than an order of magnitude, 

with the exception of barium and chromium. However, target organ analyses were scant and 

improper test phases were often used. Also, long-term exposures, which are particularly relevant 

to assessing impacts of development operations, have been studied; thus, a bioaccumulation 

potential for those discharges has been qualitatively demonstrated, but cannot be assed 

quantitatively at this time. Bioaccumulation of organics from drilling fluids, in particular those 

associated with (diesel or mineral) oils added as lubricants, has not been studied. However, such 

studies of these oils themselves or their component substances indicate that a variety of their 

toxic constituents can be bioaccumulated. Nonetheless, only a qualitative conclusion may be 

reached 

10.3. CRITERION 3 

The composition and vulnerability of the biological communities which may be 

exposed to such pollutants, including the presence of unique species or communities 

of species, the presence of species identified as endangered or threatened pursuant 

to the Endangered Species Act, or the presence of those species critical to the 

structure or function of the ecosystem, such as those important for the food chain. 

During exploratory drilling, muds and cuttings are typically discharged onto sea ice. This may 

block sunlight and reduce photosynthesis of plankton in the water column in the immediate 

vicinity of the drill site. 
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When solids are discharged, benthic communities (algae, kelp, invertebrates) may be adversely 

impacted by smothering due to sediment accumulations. This would only occur within 100-

meters of a discharge location. A worst case analysis for the High Resource Scenario (25

exploratory wells and 11 delineation wells) indicates that less than 0.0001 percent of the area of 

coverage would receive deposition of drilling mud in amounts thought to have an adverse impact 

on benthic communities [i.e., 1 cm (0.4 in)]. However, recovery of the affected benthic 

communities likely would occur within 1-2 years after the termination of discharges. 

Benthic organisms within 100 m of a discharge will likely experience temporary sublethal effects 

with some lethal effects on immature stages due to trace metals. Research on the chemical 

toxicity of drilling muds has indicated that larval stages and planktonic organisms are the most 

sensitive of the Alaskan species that have been evaluated. It is unlikely that organisms would be 

exposed for periods of time typically used to determine acute toxicity since drilling mud 

discharges are episodic with durations of only a few hours. Additionally, recovery of the 

affected benthic organisms likely would occur within 4 months (Currie and Isaacs, 2004) to 2 

years after the termination of discharges. 

Discharges may have potential toxic effects to fishes. Water quality tests indicate that lethal 

concentrations are generally present only within a few meters of the discharge point. The effect 

on fish depends on the dilution of the discharge. In shallow depths with poor circulation, the 

effect is a reduction in prey species. Demersal eggs could be smothered if discharge of solids 

occurs in a spawning area during egg production. While no specific demersal fish spawning 

locations have been identified in any of the Arctic areas of coverage, a number of important 

species, including most cottids and eelpout, possess demersal eggs. Although unlikely during 

exploratory activities in the Area of Coverage due to the anticipated emphasis on deeper offshore 

drilling sites, demersal eggs could be smothered if discharge in a spawning area coincides with 

the period of egg production. Exploratory operations in state waters are more likely to adversely 

impact demersal fish spawning activities because spawning grounds are more commonly found 

in nearshore waters. The potential of drilling muds and cuttings to smother demersal fish eggs is 

probably the most serious potential impact of exploratory drilling to fish species. Little effect to 

fish species was noted in depths of 66 ft or shallower with dissipating tidal or current action. 

The most common effect to fishes would be displacement due to avoidance; however, this would 

only be a short distance (less than 100 m) and the effects would be temporary (less than 2 years). 

Discharges in shallow, ice-covered waters are presently restricted; therefore, the likelihood that 

fishes would be exposed to discharges during their critical overwintering period for relatively 

long periods of time in areas of little circulation is reduced. It is expected that fishes would reutilize their habitat upon completion of the exploration activities. 

Seasonal distribution of birds in the region determines their vulnerability to potentially adverse 

factors associated to a large extent with oil and gas exploration. Discharges from drilling 

operations during exploration typically disperse rapidly in the surrounding water, although some 

may be deposited on the bottom near drill sites. Because bottom-feeding sea ducks and 

guillemots occur in dispersed flocks, relatively few are expected to occur in or rely specifically 

on prey potentially affected or buried at the projected drill sites under this general permit. 
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Additionally, drill structures are likely to be quite dispersed; thus, discharges are not likely to 

cause significant effects either through direct contact with birds or by affecting prey availability 

as a result of the authorized discharges. In addition, there is likely sufficient time between 

discharges at individual sites for regional bird populations to recover from the minor effects that 

may result at each site. 

Whales are seasonal feeders, obtaining their food primarily on their summer range. The 

consumption of contaminated prey items could result in the bioaccumulation of metals (i.e., 

cadmium or organic forms of mercury) by whales, potentially resulting in toxicity. The degree 

to which food supplies of these whales would be impacted would depend on the area affected 

and the concentrations of these metals in the discharge. Based on the limited areal extent of 

impacts in relation to the total area containing potential prey, the episodic nature of the 

discharges, the low concentrations of metals in the discharge, and the mobility of whales and 

their prey, the discharge is not likely to adversely affect the listed whale species. It is likely that 

whales will avoid the activity occurring in the drilling areas and thus avoid contact with prey 

residing within the more concentrated portions of the plume during discharge. The majority of 

bowhead whales exposed to recordings of drillship noise in the Area of Coverage oriented away 

from the noise source. Noise levels eliciting an avoidance response were estimated to extend 4-

11 km (2-6 nmi) from a drillship, which is much greater (100 times) than the affected area due to 

the discharge (100 m). 

There are ten (10) threatened and endangered species within the Area of Coverage: three avian 

species (short-tailed albatross, spectacled eider, and Steller’s eider), six cetacean species 

(bowhead, blue, fin, humpback, right, and sperm whales), and one pinniped (Steller sea lion). 

These species live or spend a significant portion of their lives in the Area of Coverage. Impacts 

to these species may potentially occur from behavioral changes resulting from drillship noise, 

drilling support activities, and impacts to potential prey or exposure from bioaccumulation of 

contaminants. Based on the limited areal extent of impacts in relation to the total lease area 

containing prey, and the mobility of these species, impacts are judged to be minimal. (See 

general discussions in previous paragraphs.) 

10.4. CRITERION 4 

The importance of the receiving water area to the surrounding biological 

community, including the presence of spawning sites, nursery/forage areas, 

migratory pathways, or areas necessary for other functions or critical stages in the 

life cycle of an organism. 

Kelp beds are important habitats for various populations within the area. The areas of 

concentrated macroalgal growth that have been identified include Skull Cliff, Steffansson Sound 

(Boulder Patch), Stockton Islands, Flaxman Island, Demarcation Bay, Elson Lagoon, and an area 

approximately 25 km (13.5 nmi) southwest of Wainwright in water depths of 11 to 13 m (36 to 

43 ft). 

Larger river systems and estuaries provide important spawning and rearing areas for anadromous 
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fishes. Most marine species spawn in shallow coastal areas during the winter. The Colville, 

Kokolik, Utukok, Kukpowruk, Kuk and Yukon rivers are known critical areas. High spawning 

densities of pacific herring are common at Bluff, from Cape Darby to Moses Point, Norton Bay, 

Cape Denbigh-Arctic Hills, and the area to the east of 164° W, east of the St. Michael and Stuart 

Islands. 

The ice patterns are a major determinant of the distribution of marine mammals within the Area 

of Coverage. The importance of pack ice (which extends poleward), fast ice (which is attached 

to shore), and the flaw zone (between the pack and fast ice) changes seasonally. Polar bear dens 

are found near shorefast ice (near the Colville River) and pack ice. Shorefast ice provides 

optimum habitat for ringed seal lair construction and supports the most productive pupping areas. 

Shallow coastal areas and offshore shoals provide rich benthic feeding habitat for gray whales. 

Kasegaluk Lagoon and Peard Bay is used by beluga whales as a calving and molting ground; 

their population concentrates in the Mackenzie River estuary. Kaselagluk Lagoon is also a 

calving area for spotted seals. Outer Norton Sound could be considered a calving area for the 

walrus. 

The coastal waters are primary habitat for nesting, molting, feeding, and resting activities of 

migratory marine birds. Coastal tundra and delta areas are also important nesting areas for 

waterfowl. Eiders, terns, gulls, and guillemots nest on barrier islands. 

Designated critical habitat (molting areas) for the spectacled eider includes the YukonKuskokwim delta and adjacent marine waters, Norton Sound, Ledyard Bay, and Bering Sea 

between St. Lawrence and St. Matthew Islands. Important molting and staging areas include 

Harrison Bay, Peard Bay, Kasegaluk Lagoon, Ledyard Bay, and eastern Norton Sound. 

Designated critical habitat for Steller’s eiders includes nesting areas on the Yukon-Kuskokwim 

delta and areas on the north side of the Alaska Peninsula (Izembek Lagoon, Nelson Lagoon, and 

Seal Islands) where Steller’s eiders molt, winter, and stage during spring migration. The region 

surrounding Barrow has been identified as being important to the survival and recovery of the 

Alaska-breeding population. 

The blue whale has rarely been found in the Bering Sea. This species is rarely seen near the 

coast, except in Polar Regions when it follows the retreating ice-edge. Fin whales feed 

throughout the Bering and Chukchi Seas during the summer months, although little is known 

about their migratory pathways. Humpback, male sperm, and right whales’ summer range in the 

Bering Sea is often relatively close to shore, including major coastal embayments and channels, 

but right whales may spend a lot of time on the open sea. 

The bowhead spring migration follows fractures in the sea ice around the coast of Alaska, 

generally in the shear zone. As the whales travel east past Point Barrow, their migration is 

somewhat funneled between shore and the polar pack ice. Most of the year, bowhead whales are 

closely associated with sea ice; only during the summer is this population in relatively ice-free 

waters in the southern Beaufort Sea. 
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There is no designated critical habitat for the Steller sea lion within the area of coverage. 

In order to protect the surrounding biological community, the permit prohibits from discharges of 

muds and cuttings in the following areas: 

• In water depths less than 5 m (as measured from mean lower low water); 

• Between the shore (mainland and the barrier islands) and the 5-m isobath; 

• Within 1000 meters of the Steffansson Sound Boulder Patch (near the mouth of the 

Sagavanirktok River) or between individual units of the Boulder Patch where the 

separation between units is greater than 2000 m but less than 5000 m; 

• Within 1000 m of Thetis Island and Colville River Delta; 

• Within Omalik Lagoon; 

• Within Kasegaluk Lagoon; or 

• Within 3 mi of the following passes of Kasegaluk Lagoon: Kukpowruk Pass, Akunik 

Pass, Utukok Pass, Icy Cape Pass, Alokiakatat Pass, Naokok Pass, and Pingaorarok Pass. 

10.5. CRITERION 5 

The existence of special aquatic sites including, but not limited to, marine 

sanctuaries and refuges, parks, national and historic monuments, national 

seashores, wilderness areas, and coral reefs. 

No marine sanctuaries or other special aquatic sites, as defined by 40 CFR 125.122, are known to 

be located in or adjacent to the area of coverage. Areas of the Alaska Maritime National 

Wildlife Refuge located adjacent to the area of coverage are not likely to be adversely impacted 

by exploratory drilling operations. The “Boulder Patch” area located near the Sagavanirtok 

River is recognized as an important benthic habitat, primarily due to habitat provided by hard 

substrates and associated algal beds. In order to protect the Boulder Patch, the permit prohibits 

from discharges of muds and cuttings within 1000 m of the Steffansson Sound Boulder Patch 

(near the mouth of the Sagavanirktok River) or between individual units of the Boulder Patch 

where the separation between units is greater than 2000 m but less than 5000 m. 

10.6. CRITERION 6 

The potential impacts on human health through direct and indirect pathways. 

There is no known direct exposure pathway to humans from the discharges associated with oil 

and gas exploration in Alaska; indirect exposure is primarily from direct consumption of species 

exposed to discharges. 

Overall, significant impacts to human health are not expected to result from the limited 

discharges of drilling mud that characterize the exploratory phase in the Arctic lease sales. The 

hazard associated with consuming fish and shellfish contaminated with metals or petroleum 
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10-8 

hydrocarbons is expected to be low. The reasons for this assessment are: bioconcentration 

factors for heavy metals other than methylmercury and for mobile aromatic hydrocarbons such 

as benzene are too low to warrant concern about biomagnification; mercury, which is potentially 

the most hazardous metal, is a relatively minor constituent of drilling muds; and the areas 

affected by exploratory drilling discharges are too small to contribute substantially to the diet of 

fish or shellfish harvested by fisheries. 

10.7. CRITERION 7 

Existing or potential recreational and commercial fishing, including finfishing and 

shellfishing. 

The Colville River delta fisheries include two commercial enterprises. There is a small chum 

salmon fishery in Kotzebue Sound. Norton Sound includes important, but small, commercial 

fisheries of salmon. Disposal of drilling muds in state waters is not expected to adversely affect 

the quantity or quality of fish harvested in these fisheries. 

10.8. CRITERION 8 

Any applicable requirements of an approved Coastal Zone Management Plan. 

Waste discharges associated with oil and gas exploration in areas of coverage are consistent with 

the Alaska Coastal Management Program. 

10.9. CRITERION 9 

Such other factors relating to the effects of the discharge as may be appropriate. 

No other factors have been identified relating to the effects of the discharge. 

10.10. CRITERION 10 

Marine water quality criteria developed pursuant to Section 304(a)(I) 

The discharge of drilling muds into water depths greater than 5 m is expected to comply with 

water quality criteria at the edge of a 100-m mixing zone. 
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Eastern Beaufort Sea, Alaska. U.S. Dept. Commerce, NOAA, OCSEAP Final Report 

24:129-579. 

Truett, J.C., ed. (1984b). Proc. of a Synthesis Meeting: The Barrow Arch Environment 

and Possible Consequences of Planned Offshore Oil and Gas Development, 30 

October - 1 November, 1983, Anchorage, AK. USDOC, NOAA, OCSEAP, and 

USD01, MMS, Girdwood, AK. 
ODCE for Arctic NPDES General Permit 

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11-11 

U.S. Environmental Protection Agency. (1984). Environmental Impact Statement, Red 

Dog Mine Project Northwest Alaska – Final (EPA-10-AK-Wulik-NPDES-84) (EPA 

910/9-84-122a). U.S. Environmental Protection Agency, Water Division, Seattle, 

WA and U.S. Department of Interior, Anchorage, AK. September 1984. 

U.S. Environmental Protection Agency. (1985). Assessment of Environmental Fate and 

Effects of Discharges from Offshore Oil and Gas Operations (EPA 440/4-85/002). 

U.S. Environmental Protection Agency, Office of Water. Washington, DC. August 

1985. 

U.S. Environmental Protection Agency. (1986). Water quality criteria: Ambient aquatic 

life water quality criteria documents. Federal Register, March 11, 1986. 51:8361-

8363. 

U.S. Environmental Protection Agency. (1987). Management of Wastes from Oil and Gas 

Exploration, Development, and Production, Report to Congress. U.S. Environmental 

Protection Agency, Office of Solid Waste, Washington, DC. 

U.S. Environmental Protection Agency. (1991). Technical Support Document for Water 

Quality-based Toxics Control (EPA\505\2-90-001). U.S. Environmental Protection 

Agency, Office of Water. Washington, DC. March, 1991. 

U.S. Environmental Protection Agency. (1993a). Final Development Document for 

Effluent Limitations Guidelines and New Source Performance Standards for the 

Offshore Subcategory of the Oil and Gas Extraction Point Source category (EPA 

821-R-93-003). US Environmental Protection Agency, Office of Water. 

Washington, DC. January 1993. 

U.S. Environmental Protection Agency. (1993b). Supplemental Information for Effluent 

Limitation Guidelines and New Source Performance Standards for the Offshore 

Subcategory of the Oil and Gas Extraction Point Source Category (40 CFR 435). US 

Environmental Protection Agency, Office of Water. Washington, DC. 

U.S. Environmental Protection Agency. (1995). Ocean Discharge Criteria Evaluation for 

Area of Coverage under the Arctic NPDES General Permit for Oil and Gas 

Exploration. US Environmental Protection Agency, Region 10, Office of Water. 

Seattle, WA. March 1995. 

U.S. Environmental Protection Agency. (1999a). USEPA, Office of Water, written 

comments to Dan Chadwick, EPA/OECA. September 1999. 

U.S. Environmental Protection Agency. (1999b). Development Document for Proposed 

Effluent Limitations Guidelines and Standards for Synthetic-Based Drilling Fluids 

and other Non-Aqueous Drilling Fluids in the Oil and Gas Extraction Point Source 

Category (EPA-821-B-98-021). US Environmental Protection Agency, Office of 

Water. Washington, DC. February 1999. 
ODCE for Arctic NPDES General Permit 

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11-12 

U.S. Environmental Protection Agency. (2000a). Environmental Assessment of Final 

Effluent Limitations Guidelines and Standards for Synthetic-Based Drilling Fluids 

and other Non-Aqueous Drilling Fluids in the Oil and Gas Extraction Point Source 

Category (EPA-821-B-00-014). US Environmental Protection Agency, Office of 

Water. Washington, DC. December 2000. 

U.S. Environmental Protection Agency. (2000b). EPA Office of Compliance Sector 

Notebook: Project Profile of the Oil and Gas Extraction Industry (EPA/310-R-99-

006). US Environmental Protection Agency, Office of Enforcement and Compliance 

Assurance. Washington, DC. October 2000. 

U.S. Environmental Protection Agency. (2002). National recommended water quality 

criteria: 2002 (EPA-822-R-02-047). U.S. Environmental Protection Agency, Office 

of Water, Office of Science and Technology, Washington, D.C. 33 pp. 

U.S. Fish and Wildlife Service. (1993). Final Environmental Assessment. FinalRrule to 

Authorize theIincidental Take of Small Numbers of Polar Bear and Walrus during Oil 

and Gas Activities in the Beaufort Sea and Adjacent Coastal Alaska. 

U.S. Fish and Wildlife Service. (2001). Short-tailed Albatross (Phoebastria albatrus) 

Threatened and Endangered Species. 

http://alaska.fws.gov/fisheries/endangered/pdf/STALfactsheet.pdf 

Wilber, P. (1992). Case Studies of the Thin-layer Disposal of Dredged Material - Fowl 

River, Alabama. Environmental Effects of Dredging, Vol. D-92-5. U.S. Army Corps 

of Engineers, Waterways Experiment Station, Vicksburg, MS. 
ODCE for Arctic NPDES General Permit 

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APPENDIX A 

FIGURES 
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A-1 

Figure 1-1. Arctic NPDES General Permit Area of Coverage
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A-2 

Figure 3-1. Approximate Pattern of Initial Particle Deposition. (Houghton et al., 1981
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A-3 
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A-4 

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APPENDIX B 

TABLES 
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B-1 

Table 2-1. Eight Generic Drilling Mud Compositions (USEPA, 1985) 

Seawater/Potassium/Polymer Mud Seawater/Freshwater Gel Mud 

Components #/BBL Components lb/bbl 

KCl 5 – 50 Attapulgite or Bentonite Clay 10 – 50 

Starch 2 – 12 Caustic 0.5 – 3 

Cellulose Polymer 0.25 – 5 Cellulose Polymer 0 – 2 

XC Polymer 0.25 – 2 Drilled Solids 20 – 100 

Drilled Solids 20 – 100 Barite 0 – 50 

Caustic 0.5 – 3 Soda Ash/Sodium Bicarbonate 0 – 2 

Barite 0 – 450 Lime 0 – 2 

Seawater As Needed Seawater/Freshwater As Needed 

Seawater Lignosulfonate Mud Lime Mud 

Components #/BBL Components lb/bbl 

Attapulgite or Bentonite 10 – 50 Lime 2 – 20 

Lignosulfonate 2 – 15 Bentonite 10 – 50 

Lignite 1 – 10 Lignosulfonate 2 – 15 

Caustic 1 – 5 Lignite 0 – 10 

Barite 25 – 450 Barite 25 – 180 

Drilled Solids 20 – 100 Caustic 1 – 5 

Soda Ash/Sodium Bicarbonate 0 – 2 Drilled Solids 20 – 100 

Cellulose Polymer 0.25 – 5 Soda Ash/Sodium Bicarbonate 0 – 2 

Seawater As Needed Freshwater As Needed 

Nondispersed Mud Spud Mud (slugged intermittently with seawater) 

Components #/BBL Components lb/bbl 

Bentonite 5 – 15 Attapulgite or Bentonite 10 – 50 

Acrylic Polymer 0.5 – 2 Lime 0.5 – 1 

Barite 25 – 180 Soda Ash/Sodium Bicarbonate 0 – 2 

Drilled Solids 20 – 70 Caustic 0 – 2 

Freshwater As Needed Barite 0 – 50 

 Seawater As Needed 

Lightly Treated Lignosulfonate 

Freshwater/Seawater Mud Lignosulfonate Freshwater Mud 

Components #/BBL Components lb/bbl 

Bentonite 10 – 50 Bentonite 10 – 50 

Barite 0 – 180 Barite 0 – 450 

Caustic 1 – 3 Caustic 2 – 5 

Lignosulfonate 2 – 6 Lignosulfonate 4 – 15 

Lignite 0 – 4 Lignite 2 – 10 

Cellulose Polymer 0 – 2 Drilled Solids 20 – 100 

Drilled Solids 20 – 100 Cellulose Polymer 0 – 2 

Soda Ash/Sodium Bicarbonate 0 – 2 Soda Ash/Sodium Bicarbonate 0 – 2 

Lime 0 – 2 Lime 0 – 2 

Seawater to Freshwater Ratio 1:1 approx. Freshwater As Needed 

 lb/bbl = pounds per barrel 
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B-2 

Table 2-2. Metals Concentrations in Barite Used in Drilling Fluids 

Metal “Clean” Barite Concentrations 

(mg/kg) 

Cadmium 1.1 

Mercury 0.1 

Aluminum 9,069.9 

Antimony 5.7 

Arsenic 7.1 

Barium 359,747.0 

Beryllium 0.7 

Chromium 240.0 

Copper 18.7 

Iron 15,344.3 

Lead 35.1 

Nickel 13.5 

Selenium 1.1 

Silver 0.7 

Thallium 1.2 

Tin 14.6 

Titanium 87.5 

Zinc 200.5 

Source: EPA 821-R-93-003 (Offshore ELG Development Document); Table XI-6 
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B-3 

Table 2-3. Concentration of Organic Pollutants in Three Mineral Oils (Battelle, 1984) 

Concentration in Oils (mg/kg) Chemical Oil A Oil B Oil C 

Benzene ND ND ND 

Ethylbenzene ND ND ND 

Naphthalene 50 ND ND 

Fluorene ND 150 10 

Phenanthrene ND 200 40 

Phenol ND ND ND 

Alkylated benzenes 30,000 ND ND 

Alkylated naphthalenes 280 690 ND 

Alkylated fluorenes ND 1,740 ND 

Alkylated phenanthrenes ND 140 ND 

Alkylated phenols ND ND ND 

Alkylated biphenyls 230 5,570 20 

Alkylated dibenzothiaphenes ND 370,000 ND 

ND = not detected. 
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B-4 

Table 2-4. Water Quality Data for Drilling Cuttings (CENTEC, 1984) 

Range of Concentration Pollutant Before Washing After Washing 

Conventional Parameters 

pH (s.u.) 5.70 – 8.42 7.00 – 9.20 

Specific gravity (kg/L) 1.26 – 2.07 0.98 – 1.59 

BOD-5 (mg/kg) 325 – 4,130 3,890 – 8,950 

UOD-20 (mg/kg) 2,640 – 10,500 12,800 – 26,600 

TOC (mg/kg) 58,300 – 64,100 23,000 – 27,200 

COD (mg/kg) 190,000 – 291,000 90,600 – 272,000 

Oil & Grease (mg/kg) 54,200 – 130,000 8,290 – 108,000 

Metals (mg/kg) 

Zinc 107 – 2,710 114 – 3,200 

Beryllium <1.0 <1.0 

Aluminum 6,020 – 10,900 5,160 – 10,500 

Barium 34 – 84.8 27.2 - 235 

Iron 16,600 – 30,800 17,400 – 20,600 

Cadmium 0.402 – 16.4 0.408 – 15.8 

Chromium 9.48 – 11.7 10.7 - 12 

Copper 20.6 – 55.3 20.4 – 42.6 

Nickel <6 – 12.1 6.2 – 15.9 

Lead 21.4 - 298 47.6 - 264 

Mercury 0.09333 – 0.4893 0.0920 – 0.944 

Silver 0.447 – 0.574 0.222 – 0.568 

Arsenic 7.07 – 10.3 7.0 – 10.6 

Selenium <3.0 <3.0 

Antimony <0.06 - <0.35 <0.06 - <0.35 

Thallium 0.235 – 0.57 0.134 – 0.866 

Organics (μg/kg) 

Acenaphthene 677 – 38,800 -- 

Naphthalene 3582 – 149,000 63,500 

4-Nitrophenol 30,400 -- 

N-Nitrosodiphenylamine 2,870 – 56,500 3,150 – 24,300 

Bis (2-ethylhexyl) Phthalate -- 17,300 

Phenanthrene 59,900 – 145,000 25,800 – 65,700 

Pyrene 18,900 7,860 

Dibenzothiophene 37,300 15,000 

Dibenzofuran 2,150 – 33,700 21,700 

N-Dodecane 23,000 – 403,000 6,300 – 185-000 

Diphenylamine 56,500 5,900 – 23,400 

Alphaterpineol -- 6,310 

Biphenyl 4,230 – 69,400 1,170 – 33,000 
ODCE for Arctic NPDES General Permit 

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B-5 

Table 2-5. Pollutant Concentrations in Untreated Deck Drainage (USEPA, 1993a) 

Pollutant Range of 

Concentration Pollutant Range of Concentration 

Temperature (°C) 20-32 

Conventionals (mg/L)

pH 

BOD 

TSS 

Oil and Grease 

6.6-6.8 

<18-550 

37.2-220.4 

12-1,310 

 

Nonconventionals (μg/L)

TOC (mg/L) 

Aluminum 

Barium 

Boron 

Calcium 

Cobalt 

Iron 

Magnesium 

Manganese 

Molybdenum 

Sodium 

Tin 

Titanium 

Vanadium 

Yttrium 

21-137 

176-23,100 

2,420-20,500 

3,110-19,300 

98,200-341,000 

<20 

830-81,300 

50,400-219,000 

133-919 

<10-20 

151x104

-

568x104

<30 

4-2,030 

<15-92 

<2-17 

 

Priority Metals (μg/L)

Antimony 

Arsenic 

Beryllium 

Cadmium 

Chromium 

Copper 

Lead 

Mercury 

Nickel 

Selenium 

Silver 

Thallium 

Zinc 

<4-<40 

<2-<20 

<1-1 

<4-25 

<10-83 

14-219 

<50-352 

<4 

<30-75 

<3-47.5 

<7 

<20 

2,970-6,980 

Priority Organics (μg/L)

Acetone 

Benzene 

m-Xylene 

Methylene chloride 

N-octadecane 

Naphthalene 

o,p-Xylene 

Toluene 

1,1-Dichloroethene 

ND-852 

ND-205 

ND-47 

ND-874 

ND-106 

392-3,144 

105-195 

ND-260 

ND-26 

*Ranges for four samples, two each, at tow of the three facilities in the three-facility study. 
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B-6 

Table 2-6. Quantities of Discharges in Arctic Alaska (1997-2003) 

Discharge Quantity Dischargeda 

Drilling Fluids & Cuttings 

11,399 bbl 

7,212 bbl 

1,197 bbl 

6,607 bbl & 1,650 bbl, respectively 

1,086 bbls (drilling fluids only) 

Sanitary & DomesticWaste 

4,029 gpd 

517 gpd & 518 gpd, respectively 

565 gpd & 5,793 gpd, respectively 

1,633 gpd 

2,419 gpd 

2,500 gpd 

75,150 gpd 

75,000 gpd 

975 gpd 

868 gpd 

Excess Cement Slurry 

260 bbls 

200 gpd 

43 gpd 

9,129 gpd 

6,300 gpd 

Desalination Unit Waste 

12,600 gpd 

7,275 gpd 

31,518 gpd 

36,730 gpd 

8,032 gpd 

6,315 gpd 

5,600 gpd 

140,000 gpd 

174 gpd 

Boiler Blowdown 

6.2 gpd 

7 gpd 

47 gpd 

586 gpd 

40 gpd 

27 gpd 

38 gpd 

Non-contact Cooling Water 202,380 gpd 

209,435 gpd 

Uncontaminated Bilge Water 270 gpd 

195 gpd 

Uncontaminated Ballast Water 

40 gpd 

1,857 gpd 

113,000 gpd 

2,254,000 gpd 

Deck Drainage 

213 gpd 

75,061 gpd 

78,193 gpd 

75,000 gpd 

12 gpd 

Fire System Test Water 

360 gpd 

43 gpd 

370 gpd 

Mud, cuttings, cement at seafloor 94,000 gpd 

Source: USEPA Region 10 discharge monitoring data for AKG284200 from 1995-2005. 

a

 Reported numbers represent monthly discharge from a facility. 
ODCE for Arctic NPDES General Permit 

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B-7 

Table 3-1. Summary of Sediment Trace Metal Alterations from Drilling Activities 

(USEPA, 1985) 

Location Trace Metal Mackenzie River Delta Beaufort Sea 

Arsenic (As) + 

(1.2-2.5) ND 

Cadmium (Cd) + 

(2-6x) 

+ 

(2-6x) 

Chromium (Cr) + 

(4-7x) 

+ 

(1.4-2x) 

Copper (Cu) ND +

Mercury (Hg) + 

(1.2-15x) - 

Nickel (Ni) ND ND 

Lead (Pb) + 

(1.5-202x) 

+ 

(1.2-2.6x) 

Vanadium (V) ND ND 

Zinc (Zn) + 

(1.7x) 

+ 

(1.2-1.4x) 

Abbreviations: ND not determined 

 + increased levels (magnitude change in parentheses) related to drilling 

 - decreased levels related to drilling 

 + isolated increases, not a clearly distance-related pattern 
ODCE for Arctic NPDES General Permit 

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B-8 

Table 3-2. Summary Table of the Acute Lethal Toxicity of Drilling Fluid (USEPA, 1985) 

Number of 96-hour LC50 Values (

Number of 

Species Tested 

Number of 

Fluids Tested 

Number of 

Tests Not 

Determinable < 100 100 - 999 1,000 – 9,999 

Phytoplankton 1 9 12 5 0 0 7 Invertebrates 

Copepods 1 9 11 1 0 3 5 Isopods 2 4 6 0 0 0 0 Amphipods 4 11 22 0 0 0 0 Gastropods 5 5 10 0 0 0 0 Decapods 

Shrimp 9 23 66 0 0 6(1)b 5 Crab 8 18 32 1 0 0 3 Lobster 1 2 7 0 0 0 1 

Bivalves 11 22 59 19d 0 0 1 Echinoderms 2 2 4 0 0 0 0 Mysids 4 17 64 2(1)d 0 0 1 Annelids 7 14 34 3d 0 0 0 

Finfish 15 24 80 0 0 0 2 TOTALS 48 40c 303 31 (23)d 0 4 – 9 25 Percentages as a fraction of the total number of tests 

70 68 415 392e 2% 0% 2.4% (1%)b 6% 

Average percentage in a category for each group of animals 

 5.3% 0% 2.8% (2.1%)b 9.4% 

Adapted from Petrazzuolo (1983) a Placement in classes according to LC50 value. 

 Lowest boundary of range if LC50 expressed as a range. 

 Cited values if given as “>” “<”. There were 199 such LC50 values; 95 were 100,000 ppm; 20 were <3,200 ppm. 

b These include tests conducted on drilling fluids obtained from Mobile Bay, Alabama, and which may not be representative of drilli

discharged on the OCS. The value in parenthesis is the result of not including those drilling fluids. 

c The fluids used in Gerber et al., 1980, Neff et al., 1980, and Carr et al. 1980 were all supplied by API. Their characteristics were v

have been subsamples of the same fluids. If so, the total number of fluids tests would be 35. 

d Data not available. e Number of tests with actual data. 
ODCE for Arctic NPDES General Permit 

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B-9 

Table 3-3. Reported Toxicities of Synthetic-Based Drilling Fluids (LC50s ) (USEPA, 200

Algae Mollusc Copepod Amphipod 

Drilling

Fluid Skeletonema costatum Abra alba Acartia tonsa Ampelisca abdita Leptcheirus plumulosus Rhepoxynius abronius Corophium volulator M

Base Fluid with Natural Sediment (LC50) 

Diesel ND ND ND 

0.7 ml/kg 1.0 ml/kg 

879 mg/kg 

850 mg/kg 24mg/kg 840 mg/kg 

EMO ND ND ND 575 mg/kg 251 mg/kg 239 mg/kg 7146 mg/kg 

IO 2,050 mg/L 300 mg/L >10,000 mg/L 

3.0 ml/kg 4.0 ml/kg 

3121 mg/kg 

3.7 ml/kg 

2944 mg/kg 299 mg/kg 

7,100 mg/L 

>30,000 

mg/kg 

PAO 3,900 mg/L 7,900 mg/L >50,000 mg/L 

12.5 ml/kg 13.4 ml/kg 

10,690 

mg/kg 

9,636 mg/kg 975 mg/kg 

3.0 ml/kg 

12.0 ml/kg 

>30,000 

mg/kg 

Ester 60,000 mg/L >100,000 mg/L 50,000 mg/L ND ND ND ND 

Acetal >100,000 mg/L 549 mg/L >100,000 mg/L ND ND ND ND 

LAO >10,000 mg/L 1,021 mg/L >10,000 mg/L ND ND ND ND 

Whole Fluid with Natural Sediment (LC50) 

Diesel ND ND ND 1.5 ml/kg 9.4 ml/kg ND ND 

IO ND 303 mg/kg ND 1.5 ml/kg 2.3 ml/kg ND 7,131 mg/kg 

PAO 82,400 mg/L 572 mg/kg 7000 mg/L >50,000 mg/L 3.7 ml/kg 36.5 ml/kg ND >10,000 mg/kg 

Ester ND ND 

34,000-

145,000 

mg/L 

ND ND ND ND 

LAO ND 277 mg/kg ND ND ND ND 1,268 mg/kg 

Whole Fluid - No Sediment (LC50) 

IO ND ND ND ND ND ND ND 

56

ND No data PAO Polyalphaolefin EMO Enhanced mineral oil LAO Linear alpha olefin IO Internal olefin SPP Suspended particulate phase 
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B-10 

Table 3-4. OOC Model Input Parameters Held Constant 

Discharge Conditions 

Duration (hours) 1.0a 

Angle of Pipe (degrees downward from horizontal) 90.0 

Depth of Pipe Mouth (m) 0.3 

Pipe Radius 0.1 

Rig Type Jackup 

Rig Length (m) 70.1 

Rig Width (m) 61.0 

Rig Wake Effect Included 

Drilling Mud Characteristics 

Bulk Density (g/cm3) 2.085 

Initial Solids Concentration in Whole Mud (mg/L) 1,441,000 

Mud Particle Distribution 

 Volume 

Fraction in 

Settling Velocity 

Class 

Number 

Density 

(g/cm3) 

Whole Mud 

(cm3/cm3) (cm/sec) (ft/sec) 

1 3.959 0.0364 0.658 0.021600 

2 3.959 0.0364 0.208 0.006820 

3 3.959 0.0437 0.085 0.002780 

4 3.959 0.0728 0.044 0.001430 

5 3.959 0.1383 0.023 0.000758 

6 3.959 0.0364 0.013 0.000427 

Receiving Water Characteristics 

Significant Wave Height (m)a 0.6 

Significant Wave Period (sec)a 12.0 

Surface Water Density (σt) 22.0 

Density Gradient (∆σt/m) +0.1 a

 All under-ice model runs omitted the effect of waves in the model. 
ODCE for Arctic NPDES General Permit 

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B-11 

Table 3-5. Summary of OOC Model Results for Open-Water Discharge Test Cases 

Representative of the Arctic NPDES General Permit Area of Coverage 

Modeling Test Case OWC 1 OWC 2 OWC 3 

Water Depth 40 m 20 m 5 m 

Discharge Rate (bbl/h) 

 (L/h) 

1,000 

(159,091) 

750 

(119,318) 

500 

(79,545) 

Total Solids Discharged (kg) 598,742 598,742 598,742 

Unidirectional Current Speed (cm/sec) 10 10 10 

Minimum Solids Dilution at 100 m 1,173:1 1,326:1 7,400:1 

Minimum Dissolved Dilution at 100 m 1,592:1 747:1 356:1 

Maximum Depth of Deposited Mud 

(cm)a 

63.9 112.0 452.4 

Distance from Discharge for Maximum 

Mud Depth (m) 10 30 <10 

Estimated Mud Deposition Depth (cm) 

at Edge of Mixing Zonea 7.33 7.15 0.32 

Estimated Percentage of Discharged 

Solids Deposited Within the Mixing 

Zone 

39.9 84.4 98.8 

a

 Derivation of this value assumes a discharge of 598,742 kg (1,320,000 lbs) of dry drilling mud for the 

average exploratory well depth of 3,170 m (10,400 ft). 
ODCE for Arctic NPDES General Permit 

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B-12 

Table 3-6. Estimated Depth of Drilling Muds at the Edge of the Mixing Zone for Open-Water D

 Percent of Average Total Discharge 

10 25 50 100 200 300 400 

Total Drilling Mud Discharged in Kilograms (Pounds) 

Water Depth 

and 

Discharge 

Rate 

59,874 

(132,000) 

149,686 

(330,000)

229,371 

(660,000)

598,742 

(1,320,000)

1,197,484 

(2,640,000) 

1,796,226 

(3,960,000)

2,394,968 

(5,280,000)

(

40 m 

1,000 bbl/h 

(159,091 L/h) 

0.8 1.9 3.7 7.3 14.6 21.9 29.2 

20 m 

750 bbl/h 

(119,091 L/h) 

0.7 1.8 3.6 7.2 14.4 21.6 28.8 

5 m 

500 bbl/h 

(79,545 L/h) 

0.03 0.08 0.15 0.3 0.6 0.9 1.2 

Note: Shaded areas indicate model scenarios that predict a drilling mud depth of less than 1 cm in areas beyond the 100-m mixing zone 
ODCE for Arctic NPDES General Permit 

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B-13 

Table 3-7. Summary of OOC Model Results for Below-Ice Discharge Test Cases 

Representative of the Arctic NPDES General Permit Area of Coverage 

Modeling Test Case UIC 5 UIC 6 UIC 7 

Water Depth 40 m 20 m 5 m 

Discharge Rate (bbl/h) 

 (L/h) 

1,000 

(159,091) 

750 

(119,318) 

500 

(79,545) 

Total Solids Discharged (kg) 598,742 598,742 598,742 

Unidirectional Current Speed (cm/sec) 2 2 2 

Minimum Solids Dilution at 100 m 1,552:1 1,584:1 27,521:1 

Minimum Dissolved Dilution at 100 m 1,938:1 1,052:1 972:1 

Maximum Depth of Deposited Mud 

(cm)a 

67.1 257.6 487.2 

Distance from Discharge for Maximum 

Mud Depth (m) 50 <10 <10 

Estimated Mud Deposition Depth (cm) 

at Edge of Mixing Zonea 1.1 0.14 0.02 

Estimated Percentage of Discharged 

Solids Deposited Within the Mixing 

Zone 

54.6 89.5 99.3 

a

 Derivation of this value assumes a discharge of 598,742 kg (1,320,000 lbs) of dry drilling mud for the 

average exploratory well depth of 3,170 m (10,400 ft). 
ODCE for Arctic NPDES General Permit 

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B-14 

Table 3-8. Estimated Depth of Drilling Muds at the Edge of the Mixing Zone for Below-Ice D

Percent of Average Total Discharge 

10 25 50 100 200 300 

Total Drilling Mud Discharged in Kilograms (Pounds) 

Water Depth 

and 

Discharge 

Rate 59,874 (132,000) 149,686 (330,000) 229,371 (660,000) 598,742 (1,320,000) 1,197,484 (2,640,000) 1,796,226 (3,960,000) 2,

(5,

40 m 

1,000 bbl/h 

(159,091 L/h) 

0.11 0.28 0.55 1.1 2.2 3.3 

20 m 

750 bbl/h 

(119,091 L/h) 

0.014 0.035 0.07 0.14 0.28 0.42 

5 m 

500 bbl/h 

(79,545 L/h) 

0.002 0.005 0.01 0.02 0.04 0.06 

Note: Shaded areas indicate model scenarios that predict a drilling mud depth of less than 1 cm in areas beyond the 100-m mixing zone 
ODCE for Arctic NPDES General Permit 

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B-15 

Table 3-9. Summary of OOC Model Results for Shunting Test Cases 

Modeling Test Case SHC 9 SHC 10 

Water Depth (m) 40 40 

Shunting Depth (m) 20.3 35.3 

Discharge Rate (bbl/h) 

 (L/h) 

750 

(119,318) 

500 

(79,545) 

Total Solids Discharged (kg) 598,742 598,742 

Unidirectional Current Speed (cm/sec) 10 10 

Minimum Solids Dilution at 100 m 1,284:1 1,821:1 

Minimum Dissolved Dilution at 100 m 150:1 293:1 

Maximum Depth of Deposited Mud 

(cm)a 

152.4 463.3 

Distance from Discharge for Maximum 

Mud Depth (m) 20 <10 

Estimated Mud Deposition Depth (cm) 

at Edge of Mixing Zonea 9.62 2.76 

Estimated Percentage of Discharged 

Solids Deposited Within the Mixing 

Zone 

84.0 98.2 

a

 Derivation of this value assumes a discharge of 598,742 kg (1,320,000 lbs) of dry drilling mud for the 

average exploratory well depth of 3,170 m (10,400 ft). 

Table 3-10. Concentration of Trace Metals in Barite (Kramer et al., 1980) 

Samples used in solubility 

studies Values from literature review 

Metal High trace 

metal sample 

Low trace 

metal sample Vien deposits Bedded deposits 

Arsenic 67 1.8 7a 500b 

Cadmium 12 0.65 0.2-19 50b 

Cobalt 5.4 2.2 ND <5-60 

Copper 91 7.6 2-97 3-20 

Lead 1,370 0.95 4-1,220 <10 

Mercury 8.1 0.13 0.06-14 0.06-0.19 

Nickel 33 5.7 19c <5-5 

Zind 2,750 9.8 10-4,100 200b 

ND = not detected. 

a

 One analysis 

b

 Semiquantitative emission spectrographic analysis. 

c

 Mean of 83 analyses. 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-16 

Table 3-11. Concentrations (μg/g) in Molluscs, Polychaete and Brittle Star Tissues 

(EG&G, 1982) 

Pre-drilling Cruise Post-drilling Cruise Ia Post-drilling Cruise IIb 

Species Chromium Barium Chromium Barium Chromium Barium 

mollusc tissue 6.71 NA 18.5 NA 31.7 NA 

polychaete tissue 2.28 23.5 11.2 87.8 – 206 41.0 23.5 

brittle star tissue 1.49 15.2 1.12 217.8 - 372 2.87 15.2 

a

 Two weeks after pre-drilling cruise. 

b

 One year after pre-drilling cruise. 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-17 

Table 3-12. Summary of Metal Bioaccumulation Study Results (Petrazzuolo, 1983)

Metals, Enrichment Factora Test 

Organism 

Test 

Substance 

(ppm) 

Exposure 

Period 

(days) 

Duration 

Period 

(days) Ba Ca Cd Cr Cu Pb 

XC-polymerUnical fluid 20 static 0 

(50,000) 3.2 1.2 2.0 

(100,000) 6.4 1.8 2.2 

Onisimus sp., Boekosimus sp. Whole Animal not gutted (200,000) 6.0 1.4 1.5 

Barite 

5 -- 150 

50 -- 350 

5 14 2.2 

Palaemonetes pugio Whole Animal not gutted 50 

7, 48-hour 

replacement 

14 29 

Barite 0 

500 7.7 500 13 

Carapace HepatopancreasAbdominal muscle 500 

8 days 

post-ecdysis 

(48-hour 

replacement) 12 

Barite 106 0 

500 60-100 0.07 500 70-300 1 

Carapace HepatopancreasAbdominal muscle 500 50-120 1 

12.7 lb/gal 

lignosulfonate 

fluid, MAF 

(Cr=1.4 ppm) 

1 -- 6.6 

Ferrochrome 

lignosulfonate 

(Cr=0.7 ppm) 

 13 

(Cr=6.0 ppm) 64 

Mytilus edulis Soft tissue 

CrCl3 

(Cr=0.6 ppm) 50 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-18 

4, static -- 1.4 1.7 

12.7 lb/gal lignosulfonate 

fluid, MAF 

(50,000) 4 1.1 1.2 

16, static 2.5 

-- 1 1.7 

13.4 lb/gal 

lignosulfonate 

fluid MAF 

(100,000) -- 14 1.6 

-- 4.3 

Rangea cuneata Soft tissue 

(layered solid 

phase) 

4, daily 

replacement 1 2.0 

9.2 lb/gal spud 

fluid 

(40,000 MAF) 

10, static 0 2.1 

(10,000 SPP) 0 2.5 (20,000 SPP) 0 3.0 (40,000 SPP) 0 3.0 (60,000 SPP) 0 5.5 (80,000 SPP) 

4, 24-hour 

replacement 

0 7.4 

12.7 lb/gal 

lignosulfonate 

fluid 

(40,000 MAF) 

10, static 0 2.3 

(20,000 MAF) 14 0 2.9 (40,000 MAF) 14 0 3.9 (10,000 MAF) 0 2.2 

(20,000 SPP) 0 4.4 (40,000 SPP) 0 8.6 (60,000 SPP) 0 24 

Crassostreagigas Soft tissue 

(80,000 SPP) 

4, 24-hour 

replacement 

0 36 

17.4 lb/gal 

lignosulfonate 

fluid 

(40,000 MAF) 

10, static 0 0.56 

(20,000 MAF) 14 0 2.1 

Crassostreagigas Soft tissue (cont.) 

(40,000 MAF) 14 0 2.2 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-19 

Uncirculated 

lignosulfonate 

fluid 

 

(1,000) 28 0 8.8 2.6 (1,000) 28 0 10 1.2 

Low density 

lignosulfonate 

fluid 

(1,000) 14 -- 1.6 

 27 -- 2.1  -- 15 2.3 

(1,000) 14 -- 2 

 27 -- 2  -- 15 2 

FCLS 

(30) 14 -- 5.7 

 -- 14 3.2 

(100) 14 -- 6.0 

 -- 14 5.2 

(1,000) 14 -- 7.2 

Placopecten magellanicus Kidney Adductor Kidney Adductor 

 -- 14 6.0 

XC-polymer 

fluid 

36, 48-hour 

replacement 

(5,000) 3.3 1.1 1.25 

Myoxocephalus quadricornis (gutted) 

(10,000) 2.9 3.1 1.7 

a Enrichment Factor = Concentration in exposed group/concentration in controls. b References: 1. Tornberg et al., (1980) 

 2. Brannon and Rao (1979)  3. Page et al., (1980)  4. McCullock et al., (1980)  5. Liss et al., (1980)  6. Sohio Alaska Petroleum Company (1981) Abbreviations: MAF – mud aqueous fraction  SPP – suspended particulate phase  FCLS – ferrochrome lignosulfonate 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-20 

Table 3-13. Depuration of Metals Bioaccumulated during Exposure to Drilling 

Fluids or Componentsa (Petrazzuolo, 1983) 

Test Species Test 

Substance 

Exposure 

Period 

(days) 

Metal Tissue Depuration 

Levelb 

Depuration 

Period 

(days) 

Ba -90% 7 Palaemonetes 

pugio BaSO4 7 

Sr 

Whole 

animal, 

not 

gutted -90% 7 

SLF 

(LSP) 1-4 Cr -(40-65%) 7 

MDLF 4 Cr -75% 4 

(MAF) Pb -70% 4 

16 Cr -53% 1 

Rangia 

cuneata 

SLF 

(MAF) Cr 

Soft 

tissue 

-60% 3-14 

Cr Kidney +48%c 14 LDF 

(WM) 27 Cr Adductor 

muscle -63% 14 Placopectan 

magellanicus 

FCLS 14 Cr kidney -(17-54%) 14 a

 Adapted from Brannon and Rao (1979); McCulloch et al., (1980); Liss et al., (1980). 

b

 Percentage of excess metal released. 

c

 Control animals exhibited a 24% increase during the depuration period. 

Abbreviations: SLF – seawater lignosulfonate fluid 

 MDLF – medium density lignosulfonate fluid 

 LDLF – low density lignosulfonate fluid 

 MAF – mud aqueous fraction 

 WM – whole fluid
ODCE for Arctic NPDES General Permit 

1/24/06 

B-21 

Table 4-1. Fishes Located in the Area of Coverage 

Freshwater Anadromous or Resident 

Common 

Name 

Scientific Name Common Name Scientific Name Common Name 

Arctic grayling Round whitefish Burbot Slimy sculpin Lake trout Arctic blackfish Northern pike Longnose sucker Arctic lamprey 

Thymallus arcticus Prosopium cylindraceum Lota lota Cottus cognatus 

Salvelinus namaycush Dallia pectoralis Esox lucius Catostomus catostomus Lampetra japonica 

Arctic char Dolly Varden Arctic cisco Least cisco Bering cisco Broad whitefish Humpback whitefish Cum salmon Rainbow smelt Boreal smelt Ninespine stickleback Threespine stickleback Pink salmon Coho salmon Chinook salmon Sockeye salmon 

Salvelinus alphinus Salvelinus malma Coregonus autumnalis Coregonus sardinella Coregonus laurette Coregonus nasus Coregonus pidschian Onchorynchus keta Osmerus mordax dentex Osmerus eperlanus Pungitius pungitius Gastrosteus aculeatus Onchorynchus gorbuscha 

Arctic flounder Starry founder Arctic cod Saffron cod Capelin Snailfish Pacific sandlance Pacific Herring Slender eelblenny Stout eelblenny Eelpout Arctic sculpin Spotted Snailfish Sculpin Saffron cod Fourhorn sculpin Arctic staghorn sculpin Shorthorn sculpin Hamecon Yellowfin sole 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-22 

Table 4-2. Shorebirds Located in the Area of Coverage 

Location in Area of Coverage 

Common Name Scientific Name Beaufort 

Sea 

Chukchi 

Sea 

Hope 

Basin 

Norton 

Basin 

Sandhill Crane 

Eurasian Coot 

Black-bellied Plover 

American Golden-Plover 

Semipalmated Plover 

Mongolian Plover 

Common Ringed Plover 

Whimbrel 

Hudsonian Godwit 

Bar-tailed Godwit 

Black-tailed Godwit 

Ruddy Turnstone 

Black Turnstone 

Red Knot 

Great Knot 

Sanderling 

Semipalmated Sandpiper 

Western Sandpiper 

White-rumped Sandpiper 

Baird’s Sandpiper 

Pectoral Sandpiper 

Stilt Sandpiper 

Buff-breasted Sandpiper 

Wood Sandpiper 

Solitary Sandpiper 

Terek Sandpiper 

Common Sandpiper 

Least Sandpiper 

Sharp-tailed Sandpiper 

Rock Sandpiper 

Curlew Sandpiper 

Dunlin 

Long-billed Dowitcher 

Short-billed Dowitcher 

Common Snipe 

Jack Snipe 

Red-necked Phalarope 

Red Phalarope 

Double-crested Cormorant 

Pelagic Cormorant 

Red-faced Cormorant 

Black-crowned Night-Heron 

Killdeer 

Eurasian Dotterel 

Grus canadensis 

Fulica atra 

Pluvialis squatarola 

Pluvialis dominica 

Charadrius semipalmatus 

Charadrius mongolus 

Charadrius hiaticula 

Numenius phaeopus 

Limosa haemastica 

Limosa lapponica 

Limosa limosa 

Arenaria interpres 

Arenaria melanocephala 

Calidris canutus 

Calidris tenuirostris 

Calidris alba 

Calidris pusilla 

Calidris mauri 

Calidris fuscicollis 

Calidris bairdii 

Calidris melanotos 

Calidris himantopus 

Tryngites subruficollis 

Tringa glareola 

Tringa solitaria 

Xenus cinereus 

Actitis hypoleucos 

Calidris minutilla 

Calidris acuminata 

Calidris ptilocnemis 

Calidris ferruginea 

Calidris alpine 

Limnodromus scolopaceus 

Limnodromus griseus 

Gallinago gallinago 

Lymnocryptes minimus 

Phalaropus lobatus 

Phalaropus fulicaria 

Phalacrocorax auritus 

Phalacrocorax pelagicus 

Phalacrocorax urile 

Nycticorax nycticorax 

Charadrius vociferus 

Eudromias morinellus 

+ 

- 

+ 

+ 

+ 

- 

- 

+ 

+ 

+ 

- 

+ 

- 

+ 

- 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

- 

- 

- 

- 

- 

- 

- 

- 

+ 

+ 

- 

+ 

- 

+ 

* 

- 

- 

- 

- 

- 

- 

* 

- 

+ 

* 

* 

- 

- 

* 

+ 

* 

- 

* 

+ 

- 

* 

+ 

* 

* 

* 

* 

* 

- 

+ 

- 

- 

- 

- 

- 

- 

- 

- 

* 

* 

- 

* 

- 

* 

* 

- 

* 

- 

- 

- 

- 

+ 

+ 

+ 

+ 

* 

+ 

* 

+ 

- 

+ 

+ 

* 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* 

+ 

* 

+ 

+ 

+ 

+ 

* 

+ 

* 

* 

+ 

* 

* 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* 

+ 

* 

+ 

- 

+ 

+ 

* 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* 

+ 

* 

+ 

+ 

+ 

+ 

* 

+ 

* 

* 

+ 

* 

* 

+ 

+ 

+ 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-23 

Location in Area of Coverage 

Common Name Scientific Name Beaufort 

Sea 

Chukchi 

Sea 

Hope 

Basin 

Norton 

Basin 

Black Oystercatcher 

Common Greenshank 

Greater Yellowlegs 

Lesser Yellowlegs 

Spotted Redshank 

Wandering Tattler 

Gray-tailed Tattler 

Bristle-thighed Curlew 

Far Eastern Curlew 

Rufus-necked Stint 

Little Stint 

Temminck’s Stint 

Long-toed Stint 

Ruff 

Haematopus bachmani 

Tringa nebularia 

Tringa melanoleuca 

Tringa flavipes 

Tringa erythropus 

Heteroscelus incanus 

Heterosceles brevipes 

Numenius tahitiensis 

Numenius madagascariensis 

Calidris minuta 

Calidris temminckii 

Calidris subminuta 

Philomachus pugnax 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

+ 

- 

* 

- 

- 

- 

+ 

- 

- 

- 

- 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* = breeds in Area 

+ = occurs in Area (nonbreeder) 

- = not in Area 

Table 4-3. Raptors Located in the Area of Coverage 

Location in Area of Coverage 

Common Name Scientific Name Beaufort 

Sea 

Chukchi 

Sea 

Hope 

Basin 

Norton 

Basin 

Northern Harrier 

Osprey 

Rough-legged Hawk 

Bald Eagle 

White-tailed Eagle 

Golden Eagle 

Peregrine Falcon 

Gyrfalcon 

Snowy Owl 

Short-eared Owl 

Boreal Owl 

Northern Saw-whet Owl 

Merlin 

Circus cyaneus 

Pandion haliaetus 

Buteo lagopus 

Haliaeetus leucocephalus 

Haliaeetus albicilla 

Aquila chrysaetos 

Falco peregrinus 

Falco rusticolus 

Nyctea scandiaca 

Asio flammeus 

Aegolius funereus 

Aegolius acadicus 

Falco columbarius 

+ 

- 

+ 

- 

- 

+ 

* 

+ 

+ 

+ 

- 

- 

- 

* 

- 

* 

+ 

- 

* 

* 

* 

* 

* 

- 

- 

+ 

+ 

+ 

+ 

+ 

+ 

- 

+ 

+ 

* 

+ 

+ 

+ 

- 

+ 

+ 

+ 

+ 

+ 

- 

+ 

+ 

* 

+ 

+ 

+ 

- 

* = breeds in Area 

+ = occurs in Area (nonbreeder) 

- = not in Area 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-24 

Table 4-4. Seabirds Located in the Area of Coverage 

Location in Area of Coverage 

Common Name Scientific Name Beaufort 

Sea 

Chukchi Sea Hope 

Basin 

Norton 

Basin 

Red-throated Loon 

Pacific Loon 

Common Loon 

Yellow-billed Loon 

Arctic Loon 

Red-necked Grebe 

Northern Fulmar 

Pomerine Jaeger 

Parasitic Jaeger 

Long-tailed Jaeger 

Mew Gull 

Herring Gull 

Glaucous Gull 

Sabine’s Gull 

Bonaparte’s Gull 

Franklin’s Gull 

Common Black-headed Gull 

Slaty-backed Gull 

Glaucous-winged Gull 

Ivory Gull 

Ross’ Gull 

Black-legged Kittiwake 

Red-legged Kittiwake 

Arctic Tern 

Common Tern 

Aleutian Tern 

Dovekie 

Common Murre 

Thick-billed Murre 

Black Guillemot 

Pigeon Guillemot 

Horned Puffin 

Tufted Puffin 

Black-footed Albatross 

Laysan Albatross 

Mottled Petrel 

Fork-tailed Storm-Petrel 

Leach’s Petrel 

Short-tailed Shearwater 

Ancient Murrelet 

Kittlitz’s Murrelet 

Marbled Murrelet 

Parakeet Auklet 

Crested Auklet 

Least Auklet 

Gavia stellata 

Gavia pacifica 

Gavia immer 

Gavia adamsii 

Gavia arctica 

Podiceps grisegena 

Fulmarus glacialis 

Stercorarius pomarinus 

Stercorarius parasiticus 

Stercorarius longicaudus 

Larus canus 

Larus argentatus 

Larus hyperboreus 

Xema sabini 

Larus philadelphia 

Larus pipixcan 

Larus ridibundus 

Larus schistisagus 

Larus glaucescens 

Pagophila eburnea 

Rhodostethia rosea 

Rissa tridactyla 

Rissa brevirostris 

Sterna paradisaea 

Sterna hirundo 

Sterna aleutica 

Alle alle 

Uria aalge 

Uria lomvia 

Cepphus grille 

Cepphus columba 

Fratercula corniculata 

Fratercula cirrhata 

Phoebastria nigripes 

Diomedea immutablis 

Pterodroma inexpectata 

Oceanodroma furcata 

Oceanodroma leucorhoa 

Puffinus tenuirostris 

Synthliboramphus antiquus 

Brachyramphus brevirostris 

Brachyramphus marmoratus 

Aethia psittacula 

Aethia cristatella 

Aethia pusilla 

* 

+ 

+ 

* 

* 

+ 

- 

+ 

+ 

+ 

+ 

+ 

* 

+ 

- 

- 

- 

- 

- 

- 

- 

+ 

- 

* 

- 

- 

- 

- 

- 

* 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

* 

* 

- 

* 

- 

* 

+ 

* 

* 

* 

* 

+ 

* 

* 

- 

- 

- 

- 

+ 

+ 

+ 

* 

- 

* 

- 

- 

- 

* 

* 

* 

* 

* 

* 

- 

- 

- 

+ 

- 

- 

- 

* 

- 

- 

+ 

+ 

* 

+ 

+ 

- 

- 

+ 

* 

+ 

+ 

* 

+ 

* 

* 

+ 

+ 

+ 

+ 

+ 

* 

+ 

+ 

* 

* 

+ 

+ 

+ 

+ 

* 

* 

- 

* 

* 

* 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* 

+ 

* 

* 

* 

* 

+ 

+ 

- 

- 

+ 

* 

+ 

+ 

* 

+ 

* 

* 

+ 

+ 

+ 

+ 

+ 

* 

+ 

+ 

* 

* 

+ 

+ 

+ 

+ 

* 

* 

- 

* 

* 

* 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* 

+ 

* 

* 

* 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-25 

Table 4-5. Waterfowl Located in the Area of Coverage 

Location in Area of Coverage 

Common Name Scientific Name Beaufort 

Sea 

Chukchi 

Sea 

Hope 

Basin 

Norton 

Basin 

Mallard 

Tundra Swan 

Whooper Swan 

Greater White-fronted Goose 

Snow Goose 

Canada Goose 

Bean Goose 

Emperor Goose 

Green-winged Teal 

Brant 

Northern Pintail 

Northern Shoveler 

American Wigeon 

Greater Scaup 

Lesser Scaup 

Common Eider 

King Eider 

Oldsquaw 

Black Scoter 

Surf Scoter 

White-winged Scoter 

Red-breasted Merganser 

Common Merganser 

Hooded Merganser 

Garganey 

Common Pochard 

Canvasback 

Redhead 

Tufted duck 

Ring-necked Duck 

Harlequin Duck 

Common Goldeneye 

Barrow’s Godeneye 

Bufflehead 

Smew 

Anas platyrhynchos 

Cygnus columbianus 

Cygnus cygnus 

Anser albifrons 

Chen caerulescens 

Branta canadensis 

Anser fabalis 

Chen canagica 

Anas crecca 

Branta bernicla nigricans 

Anas acuta 

Anas clypeata 

Anas americana 

Aythya marila 

Aythya affinis 

Somateria mollissima 

Samateria spectabilis 

Clangula hyemalis 

Melanitta nigra 

Melanitta perspicillata 

Melanitta fusca 

Mergus serrator 

Mergus merganser 

Lophodytes cucullatus 

Anas querquedula 

Aythya ferina 

Aythya valisineria 

Aythya Americana 

Aythya fuligula 

Aythya collaris 

Histrionicus histrionicus 

Bucephala clangula 

Bucephala islandica 

Bucephala albeola 

Mergellus albellus 

+ 

* 

- 

* 

* 

* 

- 

- 

+ 

* 

+ 

+ 

+ 

+ 

- 

* 

* 

* 

+ 

+ 

+ 

+ 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

* 

* 

- 

* 

+ 

* 

- 

* 

* 

* 

* 

* 

+ 

* 

- 

* 

* 

* 

+ 

+ 

+ 

* 

- 

- 

- 

- 

- 

- 

- 

- 

* 

- 

+ 

- 

- 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* 

+ 

- 

+ 

+ 

* 

+ 

* 

+ 

+ 

* 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* 

+ 

- 

+ 

+ 

* 

+ 

* 

+ 

+ 

* 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

* = breeds in Area 

+ = occurs in Area (nonbreeder) 

- = not in Area 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-26 

Table 4-6. Summary of ESA Listed Species Occurring Within the Area of Coverage 

Species Range in Area of 

Coverage Present Status Federal Register Notice 

Birds

Short-tailed Albatross 

(Phoebastria albatross) Bering Sea Coast Endangered 65 FR 46643 07/31/00 

Spectacled Eider 

(Somateria fischeri) 

Western and Northern 

Alaska (coastal) Threatened 58 FR 27474 05/10/93 

Steller=s Eider 

(Polysticta stelleri) 

Western and Northern 

Alaska Threatened 62 FR 31748 06/11/97 

Marine Mammals

Stellar Sea Lion 

(Eumetopias jubatus) Bering Sea Endangered 62 FR 24345 05/0597 

Blue Whale 

(Balaenoptera musculus) Bering Sea Endangered 35 FR 8491 06/02/70 

Bowhead Whale 

(Balaena mysticetus) 

Chukchi Sea and 

Beaufort Sea Endangered 35 FR 8491 06/02/70 

Fin Whale 

(Balaenoptera psysalus) 

Chukchi Sea and 

Beaufort Sea Endangered 35 FR 8491 06/02/70 

Humpback Whale 

(Magaptera novaeangliae) Bering Sea Endangered 35 FR 8491 06/02/70 

North Pacific Right Whale 

(Eubalaena japonica) Bering Sea Endangered 35 FR 8491 06/02/70 

Sperm Whale 

(Physeter macrocephalus) Bering Sea Endangered 35 FR 8491 06/0270 

Table 4-7. Summary of Critical Habitat Designations for ESA Listed Species 

Occurring Within the Area of Coverage 

Species Population/DPS Present Status Federal Register Listing 

Notice 

Birds

Spectacled Eider 

(Somateria fischeri) ND Threatened 66 FR 9146 02/06/01 

Steller=s Eider 

(Polysticta stelleri) ND Threatened 66 FR 8849 02/02/01 

DPS Distinct Population Segment 

ND Not Determined 
ODCE for Arctic NPDES General Permit 

1/24/06 

B-27 

Table 4-8. Essential Fish Habitat for Species in the Area of Coverage 

Waterbody Regions 

Species Life Stage Hope 

Basin 

Norton 

Basin 

Chukchi Sea Beaufort 

Sea 

 X 

eggs X 

juveniles X 

spawning X 

Red King Crab 

adults X 

 X X 

eggs X X 

juveniles X X 

Blue King Crab 

adults X X 

 X X 

eggs X X 

larvae X 

juveniles X 

Snow Crab 

adults X X 

 X X 

juveniles X X 

Yellowfin Sole 

adults X X 

 X X 

juveniles X X 

Sculpins 

adults X X 

 X X X 

juveniles X X X 

Chinook Salmon 

adults X X X 

 X X X 

juveniles X X X 

Coho Salmon 

adults X X X 

 X X X X (rare) 

juveniles X X X X (rare) 

Pink Salmon 

adults X X X X (rare) 

 X X X 

juveniles X X X 

Sockeye Salmon 

adults X X X 

 X X X X (rare) 

juveniles X X X X (rare) 

Chum Salmon 

adults X X X X (rare) 
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Table 9-1. Trace Metal Leach Factors from Barite and Drilling Fluids 

Trace Metal Mean Seawater 

Leach Factor

Maximum Seawater 

Leach Factor

Arsenic 0.005 0.0081 

Barium 0.0021 0.0059 

Cadmium 0.11 0.24 

Chromium 0.034 0.064 

Copper 0.0063 0.015 

Iron 0.13 0.48 

Lead 0.02 0.034 

Mercury 0.18 0.064 

Nickel 0.043 0.088 

Zinc 0.0041 0.0056 

Source: Offshore Environmental Assessment (Avanti Corporation, 1993) 

Table 9-2. Soluble and Solids Metals Concentrations 

Dredged Materials Dumped at Seaa 

Metal Mean Solid Phase 

(mg/kg) 

Mean Liquid Phase 

(mg/L) 

Partition 

Coefficientb 

Arsenic 4.0 0.0049 0.0012 

Cadmium 1.2 0.0016 0.0013 

Chromium 33.0 0.0048 0.0001 

Copper 30.4 0.0027 0.0001 

Lead 29.6 0.0068 0.0002 

Mercury 0.3 0.0003 0.0010 

Zinc 68.8 0.0325 0.0005 

Arctic River and Coastal Beaufort Seac 

Copper 33.3 0.00034 0.0000102 

Lead 15.7 0.000053 0.00000034 

Zinc 124 0.00038 0.00000031 

a

 Reference: Bigham et al., 1982 

b

 Liquid phase: solid phase (kg/L) 

c Reference: MMS, 2004c 
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Table 9-3. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing Zon

to Marine Water Quality Criteria 

Case 1: Whole mud metal concentration as dissolved metal concentration. 

Predicted Concentration at Mixing Zone 

Maximum 

Whole 

Mud 

Estimated 

Dissolved 

Metal 

Acute 

Marine 

Chronic 

Marine 

Open-Water Discharge, 

Current Speed of 10 cm/sec 

Below-Ice 

Spe

Conc.a Conc.b AWQCc AWQCc Water Depth (m) 

Metal 

(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 

Arsenic 7,100 7,100 69 36 4 10 20 4 Barium 359,747,000 359,747,000 NA NA 225,972 481,589 1,010,525 185,628 Cadmium 1,100 1,100 40 8.8 0.7 1.5 3.1 0.6 Chromium 240,000 240,000 1,100 50 151 321 674 124 Copper 18,700 18,700 4.8 3.1 11.7 25.0 52.5 9.6 Iron 15,344,300 15,344,300 NA NA 9,638 20,541 43,102 7,918 Lead 35,100 35,100 210 8.1 22.0 47.0 98.6 18.1 Mercury 100 100 1.8 0.94 0.06 0.13 0.28 0.05 Nickel 13,500 13,500 74 8.2 8.5 18.1 37.9 7.0 Zinc 200,500 200,500 90 81 126 268 563 103 a Maximum measured whole mud metal concentrations in drilling muds discharged in Alaskan waters (Table 2-2)b The assumption for this comparative analysis is that all the metals in the whole mud are available to dissolve in the water coluc Alaska Marine Water Quality Criteria – these values are all dissolved.d The predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appro

model-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.
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Table 9-4. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing Zon

to Marine Water Quality Criteria 

Case 2: Dissolved fraction estimated from maximum trace metal leach factors in Table 9

Predicted Concentration at Mixing Zone 

Maximum 

Whole 

Mud 

Estimated 

Dissolved 

Metal 

Acute 

Marine 

Chronic 

Marine 

Open-Water Discharge, 

Current Speed of 10 cm/sec 

Below-Ice 

Spe

Conc.a Conc. AWQCb AWQCb Water Depth (m) 

Metal 

(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 

Arsenic 7,100 58 69 36 0.04 0.08 0.16 0.03 Barium 359,747,000 2,122,507 NA NA 1,333 2,841 5,962 1,095 Cadmium 1,100 264 40 8.8 0.2 0.4 0.7 0.1 Chromium 240,000 15,360 1,100 50 10 21 43 8 Copper 18,700 281 4.8 3.1 0.2 0.4 0.8 0.1 Iron 15,344,300 7,365,264 NA NA 4,626 9,860 20,689 3,800 Lead 35,100 1,193 210 8.1 0.7 1.6 3.4 0.6 Mercury 100 6.4 1.8 0.94 0.004 0.01 0.02 0.003 Nickel 13,500 1,188 74 8.2 0.7 1.6 3.3 0.6 Zinc 200,500 1,123 90 81 0.7 1.5 3.2 0.6 a Maximum measured whole mud metal concentrations in drilling muds discharged in Alaskan waters (Table 2-2)b Alaska Water Quality Criteria – these values are all dissolved.c The predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appro

model-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively. 
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Table 9-5. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing Zon

to Marine Water Quality Criteria 

Case 3: Dissolved fraction estimated from mean trace metal leach factors in Table 9-1

Predicted Concentration at Mixing Zone 

Maximum 

Whole 

Mud 

Estimated 

Dissolved 

Metal 

Acute 

Marine 

Chronic 

Marine 

Open-Water Discharge, 

Current Speed of 10 cm/sec 

Below-Ice 

Spe

Conc.a Conc. AWQCb AWQCb Water Depth (m) 

Metal 

(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 

Arsenic 7,100 36 69 36 0.02 0.05 0.10 0.02 Barium 359,747,000 755,469 NA NA 475 1,011 2,122 390 Cadmium 1,100 121 40 8.8 0.08 0.16 0.34 0.06 Chromium 240,000 8,160 1,100 50 5 11 23 4 Copper 18,700 118 4.8 3.1 0.07 0.16 0.33 0.06 Iron 15,344,300 1,944,759 NA NA 1,253 2,670 5,603 1,029 Lead 35,100 702 210 8.1 0.4 0.9 2.0 0.4 Mercury 100 1.8 1.8 0.94 0.001 0.002 0.01 0.001 Nickel 13,500 581 74 8.2 0.4 0.8 1.6 0.3 Zinc 200,500 822 90 81 0.5 1.1 2.3 0.4 a Maximum measured whole mud metal concentrations in drilling muds discharged in Alaskan waters (Table 2-2)b Alaska Water Quality Criteria – these values are all dissolved.c The predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appro

model-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively. 
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Table 9-6. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing Zo

to Marine Water Quality Criteria 

Case 1: Total drilling cutting metal concentration as dissolved metal concentration. 

Predicted Concentration at Mixing Zone 

Maximum 

Drilling 

Cuttting 

Estimated 

Dissolved 

Metal 

Acute 

Marine 

Chronic 

Marine 

Open-Water Discharge, 

Current Speed of 10 cm/sec 

Below-Ice 

Spee

Conc.a Conc.b AWQCc AWQCc Water Depth (m) 

Metal 

(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 

Arsenic 10,600 10,600 69 36 7 14 30 5 Cadmium 16,400 16,400 40 8.8 10.3 22.0 46.1 8.5 Chromium 12,000 12,000 1,100 50 8 16 34 6 Copper 55,300 55,300 4.8 3.1 34.7 74.0 155.3 28.5 Lead 298,000 298,000 210 8.1 187.2 398.9 837.0 153.8 Mercury 944 944 1.8 0.94 0.59 1.26 2.65 0.49 Nickel 15,900 15,900 74 8.2 10.0 21.3 44.7 8.2 Silver 574 574 1.9 -- 0.4 0.8 1.6 0.3 Selenium 3,000 3,000 290 71 2 4 8 2 Zinc 3,200,000 3,200,000 90 81 2,010 4,283 8,989 1,651 a Maximum measured drilling cutting metal concentrations (Table 2-4)b The assumption for this comparative analysis is that all the metals in the drilling cuttings are available to dissolve in the water c Alaska Marine Water Quality Criteria – these values are all dissolved.d The predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appro

model-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.
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Table 9-7. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing Zo

to Marine Water Quality Criteria 

Case 2: Dissolved metal concentration is two orders of magnitude lower than drilling cutting con

Predicted Concentration at Mixing Zone 

Maximum 

Drilling 

Cutting 

Estimated 

Dissolved 

Metal 

Acute 

Marine 

Chronic 

Marine 

Open-Water Discharge, 

Current Speed of 10 cm/sec 

Below-Ice 

Spee

Conc.a Conc.b AWQCc AWQCc Water Depth (m) 

Metal 

(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 

Arsenic 10,600 106 69 36 0.1 0.1 0.3 0.1 Cadmium 16,400 164 40 8.8 0.1 0.2 0.5 0.1 Chromium 12,000 120 1,100 50 0.1 0.2 0.3 0.1 Copper 55,300 553 4.8 3.1 0.3 0.7 1.6 0.3 Lead 298,000 2,980 210 8.1 1.9 4.0 8.4 1.5 Mercury 944 9.44 1.8 0.94 0.01 0.01 0.03 0.005 Nickel 15,900 159 74 8.2 0.1 0.2 0.4 0.1 Silver 574 574 1.9 -- 0.004 0.01 0.02 0.003 Selenium 3,000 30 290 71 0.02 0.04 0.08 0.02 Zinc 3,200,000 32,000 90 81 20 43 90 17 a Maximum measured drilling cuttings metal concentrations (Table 2-4)b The assumption for this comparative analysis is that the metals in the dissolved fraction are two orders of magnitude lower tha

(divide by 100). 

c Alaska Water Quality Criteria – these values are all dissolved.d The predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appro

model-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively. 
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Table 9-8. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing Zo

to Marine Water Quality Criteria 

Case 3: Dredged material partition coefficients are used to estimate dissolved metal concentrations in 

Predicted Concentration at Mixing Zone 

Maximum 

Whole 

Mud 

Estimated 

Dissolved 

Metal 

Acute 

Marine 

Chronic 

Marine 

Open-Water Discharge, 

Current Speed of 10 cm/sec 

Below-Ice 

Spee

Conc.a Conc.b AWQCc AWQCc Water Depth (m) 

Metal 

(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 

Arsenic 10,600 13 69 36 0.01 0.02 0.04 0.01 Cadmium 16,400 21.3 40 8.8 0.01 0.03 0.06 0.01 Chromium 12,000 1.2 1,100 50 0.001 0.002 0.003 0.001 Copper 55,300 5.5 4.8 3.1 0.003 0.01 0.02 0.003 Lead 298,000 59.6 210 8.1 0.04 0.08 0.17 0.03 Mercury 944 0.944 1.8 0.94 0.001 0.001 0.003 0.0005 Nickel 15,900 15.9 74 8.2 0.01 0.02 0.04 0.01 Silver 574 0.6 1.9 -- 0.0004 0.001 0.002 0.0003 Selenium 3,000 3 290 71 0.002 0.004 0.01 0.002 Zinc 3,200,000 1,600 90 81 1 2 4 1 a Maximum measured drilling cuttings metal concentrations (Table 2-4)b The assumption for this comparative analysis is that the metals in the drilling cuttings partition similar to that of dredged mate

drilling cutting concentrations are multiplied by the partition coefficients in Table 9-1.

c Alaska Water Quality Criteria – these values are all dissolved.d The predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appro

model-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively. 
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Table 9-9. Comparison of Sanitary Waste Predicted Total Residual Chlorine 

Concentrations (at Mixing Zone Boundary) 

to Marine Water Quality Criteria 

Predicted Concentration at Mixing Zone Boundarya (μg/L) 

TBEL Chronic 

Marine 

Open-Water Discharge, 

Current Speed of 10 cm/sec 

Below-Ice Discharge, Current 

Speed of 2 cm/sec 

Conc. AWQC Water Depth (m) 

(mg/L) (mg/L) 40 20 5 40 20 5 

1.0 0.002 0.0006 0.001 0.003 0.0005 0.001 0.001 a The predicted dissolved-metal concentrations calculated by dividing the estimated 

dissolved-metal concentration by the appropriate modified OOC model-predicted dilution 

factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively 
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APPENDIX C 

NPDES GENERAL PERMIT FOR OIL AND GAS EXPLORATION 

IN THE ARCTIC 
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APPENDIX D 

CALCULATION OF SOLIDS DEPOSITION MULTIPLIERS 
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D-1 

The OOC model scenarios used in the ODCE predict the deposition of solids after one 

hour of discharge. This time period was chosen to be consistent with the input 

parameters of earlier modeling efforts on exploratory oil and gas ODCEs. An interval of 

one hour is not sufficient time to discharge all of the drilling muds generated by an 

average exploratory well at discharge rates ranging from 250 to 1,000 bbl/h. In order to 

predict the maximum solids thickness at the completion of an exploratory well, an 

estimate for the average amount of drilling muds produced by each exploratory well is 

required. Estimates of drilling mud production for Beaufort Sea and Chukchi Sea lease 

sale areas are given below (MMS 1990, 1991): 

Region 

Average Drilling Mud 

Production Per 

Exploratory Well (kg) 

Average True Vertical 

Well Depth (m) 

Beaufort Sea 571,526 3,048 

Chukchi Sea 598,742 3,170 

In order to predict the maximum thickness of drilling mud upon completion of an 

exploratory well, a multiplier must be calculated which accounts for the production of 

drilling muds beyond the one-hour time period specified in the model. The multiplier is 

calculated by dividing the average production (given above) by the production period 

predicted after one hour, which is calculated by the following formula: 

Drilling mud production (kg) = [discharge rate (L/h)] * [solids concentration in whole mud (kg/L)]*[time (h)] 

An example calculation for the Chukchi Sea is given below: 

Drilling mud production = [(1,000 bbl/hr)*(159 L/bbl)] * (1.441 kg/L) (1 hr) = 229,119 kg 

Ratio = 598,742 kg /229,119 kg = 2.613 

Thus, all solids thickness values given in Section 3 for the case runs which included a 

discharge rate of 1,000 bbl/h were multiplied by 2.613 to represent the maximum 

completion-of-well values for an average exploratory well drilling in the Chukchi Sea. 

This method of estimating mud accumulation assumes that area deposition patterns will 

be unchanged for discharges of different quantities of mud and is reasonable provided 

that the rate of mud discharged does not vary from that predicted in the modeling. 

It should be noted that dilution values, either for solids or the dissolved fraction, are 

unaffected by the differences between the modeled and actual discharge amounts and 

would not be subject to the multiplier calculated above. 

The following table shows the multipliers for four discharge rates in the Beaufort and 

Chukchi seas. [In this ODCE, multipliers for the Chukchi Sea were applied to the entire 

Area of Coverage.] 
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D-2 

Discharge Rates (bbl/h) 

1,000 750 500 250 

Beaufort Sea 2.494 3.326 4.989 9.978 

Chukchi Sea 2.613 3.484 5.226 10.453 
ODCE for Arctic NPDES General Permit 

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APPENDIX E 

FACT SHEET 

FOR 

NPDES GENERAL PERMIT FOR OIL AND GAS EXPLORATION 

IN THE ARCTIC 
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1

Fact Sheet

U.S. Environmental Protection Agency 

Region 10 

The United States Environmental Protection Agency (EPA) 

Plans to Reissue a 

National Pollutant Discharge Elimination System (NPDES) General Permit for 

OFFSHORE OIL AND GAS EXPLORATION FACILITIES 

ON THE OUTER CONTINENTAL SHELF AND CONTIGUOUS STATE WATERS 

Permit Number: AKG280000 

Public Comment Period

 Starts: April 5, 2004 

 Ends: May 20, 2004 

Technical Contact

 Name: Kristine Koch 

 Phone: (206) 553-6705 

 1-800-424-4372 ext. 6705 (within Alaska, Idaho, Oregon, and Washington)

 Email: koch.kristine@epa.gov
2

EPA’s Tentative Determination

EPA proposes to reissue a NPDES general permit for oil and gas exploration facilities on the 

outer continental shelf and contiguous state waters. The draft permit places conditions on the 

discharge of pollutants from oil and gas exploration facilities to the Beaufort and Chukchi Seas. 

In order to ensure protection of water quality and human health, the permit places limits on the 

types and amounts of pollutants that can be discharged. 

This Fact Sheet includes: 

• information on public comment, public hearing, and appeal procedures; 

• a description of the types of facilities and the proposed discharges; 

• a listing of the proposed effluent limitations and other conditions; 

• a map and description of the proposed discharge area; and 

• technical material supporting the conditions in the permit. 

Public Comment and Public Hearings

Persons wishing to comment on the tentative determinations contained in the draft permit must 

do so, in writing, by the end date of this public comment period. All comments should include 

the name, address, and telephone number of the commenter, reference the facility name and 

NPDES permit number, and include a concise statement of the exact basis of any comment and 

the relevant facts upon which it is based. 

Persons wishing to request that a public hearing be held may do so, in writing, by the end date of 

this public comment period. A request for a public hearing must state the nature of the issues to 

be raised, reference the facility name and NPDES permit number, and include the requester’s 

name, address, and telephone number. 

All written comments and requests should be submitted to the attention of the Director, Office of 

Water at the following address: 

 U.S. EPA, Region 10 

 1200 Sixth Avenue, M/S OW-130 

 Seattle, Washington 98101 

***Comments may also be submitted electronically to the technical contact listed above***

After the Public Notice expires, and all comments have been considered, EPA’s Director for the 

Office of Water in Region 10 will make a final decision regarding permit issuance. If no 

significant comments are received, the tentative conditions in the draft permit will become final, 

and the permit will become effective upon issuance. If comments are received, EPA will address 

the comments, issue the permit, and the permit will become effective 30 days after the issuance 

date, unless the permit is appealed to the Environmental Appeals Board within 30 days. 
3

Availability of Documents

The following documents are available at the EPA Region 10 Office, 1200 Sixth Ave, Seattle, 

Washington, between 8:30 a.m. and 4:00 p.m., Monday through Friday: 

• draft permit 

• fact sheet 

• documents referenced in fact sheet 

• ocean discharge criteria evaluation (ODCE) 

• other documents (e.g., meeting reports, correspondence, trip reports, telephone memos, 

calculations, etc.) 

Copies of the draft permit, fact sheet, ODCE are also available at: 

 EPA Region 10 website: www.epa.gov/r10earth.htm

 EPA Alaska Operations Office, Anchorage 

 Federal Building, Room 537 

 222 West 7th Avenue, #19 

 Anchorage, Alaska 99513 

 Anchorage Municipal Library 

 Z. J. Loussac Public Library 

 3600 Denali St 

 Anchorage, Alaska 99503-6055 

North Slope Borough School District Library / Media Center 

Pouch 169 

Barrow, AK 99723 

State Certification

EPA is requesting that the Alaska Department of Environmental Conservation certify this 

NPDES permit for the Offshore Oil and Gas Exploration Facilities on the Outer Continental 

Shelf and Contiguous State Waters, under section 401 of the Clean Water Act for those activities 

that occur within State waters or have the ability to affect the quality of the State’s waters. EPA 

is also requesting the State to conduct a consistency determination with the Alaska Coastal 

Management Program 
4

TABLE OF CONTENTS

I. APPLICABILITY AND NOTIFICATION REQUIREMENTS .........................................6 

 A. Source ......................................................................................................................6 

 B. Area of Coverage .....................................................................................................6 

 C. Prohibited Areas of Discharge [reserved]................................................................7 

 D. Authorization to Discharge......................................................................................7 

 E. Transfers ................................................................................................................10

 F. Termination Notification .......................................................................................10 

 G. Requiring an Individual Permit..............................................................................11 

II. PROPOSED EFFLUENT LIMITATIONS AND DISCHARGE REQUIREMENTS ......11 

A. Basis for Permit Effluent Limitations....................................................................11 

B. Technology-based Evaluation................................................................................11 

C. Water Quality-based Evaluation............................................................................12 

D. Proposed Effluent Limitations ...............................................................................14 

III. PROPOSED MONITORING REQUIREMENTS.............................................................28 

A. Basis for Effluent Monitoring................................................................................28 

B. Proposed Effluent Monitoring ...............................................................................29 

IV. SPECIAL CONDITIONS..................................................................................................31 

A. Quality Assurance Plan (QAP) ..............................................................................31 

B. Best Management Practices (BMP) Plan...............................................................31 

C. Mud Plan................................................................................................................31 

V. OTHER LEGAL REQUIREMENTS ................................................................................32 

A. State Certification Requirements ...........................................................................32 

B. Standard Permit Provisions....................................................................................32 

C. Endangered Species Act of 1973 ...........................................................................33 

D. Essential Fish Habitat ............................................................................................33 

E. Permit Expiration...................................................................................................33 

F. Ocean Discharge Criteria.......................................................................................33 

G. Coastal Zone Management Act (CZMA) ..............................................................34 

H. Oil Spill Requirements...........................................................................................34 

VI. REFERENCES ......................................................................................................35 

APPENDIX A Description of Discharges 

APPENDIX B Maps 

APPENDIX C Basis for Water Quality-based Effluent Limitations 

APPENDIX D Calculations 
5

LIST OF TABLES

Table 1 Alaska Technology-based Effluent Limitations for Sanitary Wastes (003) ..........22 

Table 2 Proposed Effluent Monitoring Requirements ........................................................16 

Table C-1 Water Quality Criteria Applicable to the General Permit Discharges within 

Alaska Waters ......................................................................................................C-1 

Table D-1 Reasonable Potential Analysis for Total Residual Chlorine............................... D-1 

Table D-2 Waste Load Allocation for Total Residual Chlorine .......................................... D-1 

Table D-3 Water Quality-based Effluent Limits for Total Residual Chlorine..................... D-2 

Table D-4 Reasonable Potential Analysis for Fecal Coliform Bacteria .............................. D-3 

LIST OF FIGURES

Figure B-1. Active MMS Leases in the Beaufort Sea.............................................................B-1 

Figure B-2. Arctic General Permit Area of Coverage.............................................................B-2 
6

I. APPLICABILITY AND NOTIFICATION REQUIREMENTS 

A. Source. 

 The federal regulations at 40 CFR 122.28 require that general permits cover one 

or more categories or subcategories of discharges. The proposed general permit 

covers only those facilities engaged in field exploration and drilling activities 

under the Offshore Subcategory of the Oil and Gas Extraction Point Source 

Category (40 CFR 435 Subpart A). Exploratory operations are defined as those 

operations involving the drilling of well s to determine the nature of potential 

hydrocarbon reserves. Development and production operations are not covered 

by this general permit. 

 The draft general permit proposes to authorize the following discharges from 

exploratory offshore oil and gas operations: drilling mud and drilling cuttings; 

deck drainage; sanitary wastes; domestic wastes; desalination unit wastes; 

blowout preventer fluid; boiler blowdown; fire control system test water; noncontact cooling water; uncontaminated ballast water; uncontaminated bilge water; 

excess cement slurry; mud, cuttings, and cement at the seafloor; and test fluids. 

Further description of these discharges is provided in Appendix A of this fact 

sheet. 

 The draft general permit proposes to exclude authorization for “new sources” 

which include development and production operations. A development facility is 

any fixed or mobile structure that is engaged in the drilling of productive wells 

and a production facility is any fixed or mobile structure that is either engaged in 

well completion or used for active recovery of hydrocarbons from producing 

formations. 

 In the context of this point source category for exploration facilities, an offshore 

mobile exploratory drilling rig is considered an existing discharger except when it 

is in the area of biological concern in which it is then considered a new 

discharger. A new discharger is not a new source and is not subject to the 

requirements of NEPA. EPA will make the determination for authorization of a 

facility under this general permit on a case-by-case basis from the information 

supplied by the applicant in the Notice of Intent (NOI). Only existing sources and 

new dischargers may be authorized under this general permit. 

B. Area of Coverage. 

1. Geographic Area. The federal regulations at 40 CFR 122.28(a) require 

that the geographic area of coverage correspond to existing geographic or 

political boundaries. In order to be consistent with lease sales conducted 

by MMS on the outer continental shelf (OCS) or lease sales conducted by 
7

the state of Alaska within the boundaries of state waters, EPA has defined 

the area of coverage for this general permit to correspond with MMS OCS 

regions of the Beaufort and Chukchi Seas and state of Alaska waters 

contiguous to the landward boundary of these MMS OCS regions. 

Currently, the only MMS active leases are in the Beaufort Sea. All MMS 

leases have been relinquished for the Chukchi Sea. A map showing the 

active leases is provided in Appendix B of this fact sheet. 

2. Source Area. The applicability of the Offshore Subcategory of the Oil and 

Gas Extraction Point Source Category (40 CFR 435, Subpart A) is to those 

facilities which are located in waters that are seaward of the inner 

boundary of the territorial seas as defined in section 502(8) of the Clean 

Water Act. The inner boundary of the Beaufort and Chukchi seas is either 

the line of ordinary low water along that portion of the coast which is in 

direct contact with the open sea or the line marking the seaward limit of 

inland waters (i.e., inner boundary baseline). Since the inner boundary 

baseline in Alaska has not been clearly established, applicants discharging 

to bays, inlets, or other water bodies that may be construed as inland 

waters will be required to confirm with the U.S. Department of State and 

the National Oceanic and Atmospheric Administration (NOAA) that their 

discharge is seaward of the inner boundary baseline. 

3. A map of the coverage area is provided in Appendix B of this fact sheet. 

C. Prohibited Areas of Discharge. [reserved] 

D. Authorization to Discharge. 

1. Application. The federal regulations at 40 CFR 122.28(b)(2)(i) allows a 

complete and timely notice of intent (NOI) to be covered in accordance 

with the general permit requirements to fulfill the requirements for permit 

applications. 

2. Notice of Intent Contents. The federal regulations at 40 CFR 

122.28(b)(2)(ii) require the contents of the NOI to contain information 

necessary for adequate program implementation, legal name and address 

of the owner or operator, the facility name and address, the type of facility 

or discharges, and the receiving stream(s). In additions to these 

requirements, EPA is including the following requirements as part of the 

NOI: 

a. Applicant: The current permit requires that the applicant provide 

the name and address of the permittee and the facility name and 

location. The current permit requires the applicant to provide the 

owner’s or operator’s: name, mailing address, contact name, and 
8

telephone number; and the facility’s name, mailing address, 

contact name, and telephone number. 

b. Location of discharge: The current permit requires that the 

applicant provide the leaser (MMS or ADNR) the lease and block 

numbers of operations and discharges; the latitude and longitude of 

facility and each well; the range of water depths below mean lower 

low water (MLLW) in the lease block; and the water depths for 

each discharge. This information requirement is retained in the 

draft permit. In addition, the draft permit is proposing that the 

applicant provide the type of drilling rig (e.g., jackup, drillship, 

semisubmersible) used for exploratory operations and the receiving 

water. 

c. Mobile operations: The current permit does not allow for mobile 

operations; facilities must submit a separate NOI for each location. 

In other NPDES permits, EPA has allowed mobile operations as 

long as the permittee provides the area of discharge in their 

application and notifies EPA of their exact location during 

operations. The draft permit proposes the authorization of mobile 

operations as long as the facility initially applies for mobile 

operations, provides a map and description of the area they are 

going to operate in, provides the initial location of the facility, and 

notifies EPA, in writing, of the new location 30 days prior to 

moving their operation. 

d. Commencement date of discharge: The current permit requires the 

applicant provide the initial date and expected duration of 

exploration operations. This information requirement is retained 

in the draft permit. 

e. Special monitoring: The current permit requires environmental 

monitoring of drilling muds and drill cuttings when the discharge 

is within 4000 meters of the following areas: below-ice to water 

depths shallower than 20 meters as measured from MLLW; the 

Steffansson Sound Bouldeer Patch, the protected areas of 

Kasegaluk Lagoon and the seven identified passes; Omalik 

Lagoon, or river mouths or deltas during unstable or broken ice or 

open water conditions. The draft permit retains this requirement 

and requires the applicant to indicate whether or not they are 

subject to the special monitoring requirements. 

f. Environmental reports: The current permit requires that the 

applicant provide copies of any exploration plans, biological 

surveys, and environmental reports required by MMS for the 
9

identification or protection of biological populations or habitats, or 

provide notice that no exploration plan or environmental report 

will be sent. This information requirement is retained in the draft 

permit. 

g. Wells: The current permit does not require the applicant to submit 

any well specific information. The current permit proposes to 

require the applicant to submit the initial date of drilling for each 

well, the well name, the well number (i.e., #1, #2,... #5), the well 

hole diameter, the category of mud(s) used (e.g., water-based, oilbased, synthetic-based), the type or group of mud used (e.g., 

lignosulfonate muds, lime muds, etc.), solids removal process, and 

certification of complete Mud Plan. 

h. Discharges: The current permit authorizes each applicant to 

discharge all discharges under the permit. The draft permit 

authorizes each applicant to discharge only those discharges in 

which they apply to discharge. Additionally, the draft permit 

requires the applicant to indicate the type of sanitary discharge 

(M10 or M9IM). 

i. Line Drawing: The current permit does not require the applicant to 

provide a line drawing that shows the flow of discharged 

wastestreams through the facility. To be consistent with the 

application requirements of 40 CFR 122.21, the draft permit is 

requiring the applicant to submit a line drawing with the NOI. 

3. Deadlines for Submitting Notice of Intent. The federal regulations at 40 

CFR 122.28(b)(2)(iii) require general permits to specify the deadline to 

submit a notice of intent to be covered under the permit. The current 

permit requires that the applicant provide: notice of request to discharge 

60 days prior to initiation of discharge; information about the discharge 30 

days prior to commencement of discharges; and notice of intent to 

commence discharge, orally or written, 7 days prior to discharging from 

the facility and from each well. If information required to be submitted 7 

days prior to discharging was given orally, the applicant was required to 

provide written confirmation within 7 days. 

 EPA has found these deadlines to be laborious, difficult to track, and 

confusing to the applicant(s). Therefore, the draft permit proposes that the 

applicant submit a notice of intent to be covered under this general permit 

thirty (30) days prior to commencement of discharges from any facility. 

 The draft permit proposes to only authorize information to be given in 

writing. In addition, the permittee must submit a new complete notice of 
10

intent prior to the expiration date of the general permit should the operator 

choose to continue operations under this general permit in the event of 

administrative extension of the general permit. 

4. Date(s) when a discharger is authorized to discharge. The federal 

regulations at 40 CFR 122.28(b)(2)(iii) require general permits to specify 

the date(s) when a discharger is authorized to discharge under the permit. 

The date when a discharger is authorized to discharge under the current 

permit is the date that they receive written notification that EPA has 

assigned a permit number under the general permit. The date when a 

discharger is authorized to discharge for the draft permit is the date of the 

written notification that EPA has authorized the discharge and assigned a 

permit number under the general permit. 

E. Transfers. The federal regulation at 40 CFR 122.41(l)(3) allows for transfers of 

permits. Transfers under the draft permit will only be authorized for an existing 

facility located at the site or area of the original NOI. Discharge authorizations 

may not be transferred to new facilities, an existing facility previously located at a 

different site (e.g., if a facility is located at site A, then it cannot move to site B 

without obtaining new permit coverage, even if there was previous permit 

coverage at site B for a different facility). This is because the facility will be 

considered a “new facility” and must submit a new NOI for coverage under this 

general permit. 

F. Termination Notification. The federal regulation at 40 CFR 122.64 provides 

causes for terminating coverage under the general permit. One cause is a change 

in any condition that requires either a temporary or permanent reduction or 

elimination of any discharge controlled by the permit (for example, plant closure 

or termination of a discharge). 

1. Operations. The current general permit requires the permittee to provide a 

notice within 30 days following the cessation of discharges from the 

discharge site. The draft permit proposes that the permittee provide a 

notice prior to ceasing operations. The notice must include certification 

that the permittee is not subject to an enforcement action or citizen suit. 

In accordance with federal regulation 40 CFR 124.64, the permit coverage 

will be terminated 30 days after the discharger receives notice from EPA. 

2. Wells. The current general permit requires the permittee to provide a 

notice within 30 days following the cessation of discharges from each 

well. The draft permit proposes that the permittee provide a notice of well 

completion within 7 days of ceasing drilling operations in each well. 

G. Requiring an Individual Permit. The federal regulations under 40 CFR 

122.28(b)(3) provides the cases where the Director, the Regional Administrator, 
11

or the discharger may request an individual permit. These were incorporated into 

the general permit as stated in the federal regulations. 

II. PROPOSED EFFLUENT LIMITATIONS AND DISCHARGE REQUIREMENTS 

A. Basis for Permit Effluent Limits. 

 In general, the Clean Water Act requires that the effluent limits for a particular 

pollutant be the more stringent of either technology-based limits or water qualitybased limits. A technology-based effluent limit requires a minimum level of 

treatment for point sources based on currently available treatment technologies. 

A water quality-based effluent limit is designed to ensure that the water quality 

standards of a water body are being met. 

 B. Technology-based Evaluation 

1. Overview. 

There are two general approaches for developing technology-based 

effluent limits for industrial facilities: (1) using national effluent 

limitations guidelines (ELGs) and (2) using Best Professional Judgment 

(BPJ) on a case-by-case basis. The intent of a technology-based effluent 

limitation is to require a minimum level of treatment for industrial point 

sources based on currently available treatment technologies while 

allowing the discharger to use any available control technique to meet the 

limitations. 

The national ELGs are developed based on the demonstrated performance 

of a reasonable level of treatment that is within the economic means of 

specific categories of industrial facilities. Where national ELGs have not 

been developed or did not consider specific pollutant parameters in 

discharges, the same performance-based approach is applied to a specific 

industrial facility based on the permit writer’s BPJ. In some cases, 

technology-based effluent limits based on ELGs and BPJ may be included 

in a single permit. 
12

2. National Effluent Limitation Guidelines. 

Section 301(b) of the CWA requires technology-based controls on 

effluents. This section of the CWA requires that, by March 31, 1989, all 

permits contain effluent limitations which: (1) control toxic pollutants and 

nonconventional pollutants through the use of “best available technology 

economically achievable” (BAT), and (2) represent “best conventional 

pollutant control technology” (BCT) for conventional pollutants. In no 

case may BCT or BAT be less stringent than “best practical control 

technology currently achievable” (BPT), which is the minimum level of 

control required by section 301(b)(1)(A) of the CWA. 

For several specific industrial sectors, EPA has developed effluent 

limitation guidelines (ELGs) that contain BPT, BCT, BAT, and NSPS 

limitations. On April 13, 1979, EPA published effluent limitation 

guidelines for the offshore subcategory of the oil and gas extraction 

industry. These guidelines were subsequently amended on December 16, 

1996, and January 22, 2001. The guidelines for this industry are found in 

40 CFR Part 435, Subpart A. The BPT, BCT, and BAT effluent limitation 

guidelines (40 CFR 435.12-14) that apply to the discharges authorized by 

this general permit have been incorporated as discussed below. 

C. Water Quality-based Evaluation 

1. Overview 

In addition to the technology-based limits discussed above, EPA evaluated 

the discharges to determine compliance with section 301(b)(1)(C) of the 

CWA. This section requires the establishment of limitations in permits 

necessary to meet water quality standards by July 1, 1977. The 

regulations at 40 CFR 122.44(d) implement section 301(b)(1)(C) of the 

CWA. These regulations require that permits include limits for all 

pollutants or parameters which “are or may be discharged at a level which 

will cause, have the reasonable potential to cause, or contribute to an 

excursion above any state water quality standard, including state narrative 

criteria for water quality.” The permit limits must be stringent enough to 

ensure that water quality standards are met, and must be consistent with 

any available wasteload allocation (WLA). 

In determining whether water quality-based limits are needed and 

developing those limits when necessary, EPA follows guidance in the 

Technical Support Document for Water Quality-based Toxics Control

(TSD; EPA, 1991). The water quality-based analysis consists of four 

steps: (1) determine the appropriate water quality criteria that apply to 

each discharge, (2) determine if there is “reasonable potential” for the 

discharge to exceed the criteria in the receiving water, (3) develop a WLA 
13

if there is reasonable potential, and (4) develop effluent limitations based 

on the WLA. 

2. Water Quality Standards. 

The State’s water quality standards are composed of use classifications, 

numeric and/or narrative water quality criteria, and an anti-degradation 

policy. The use classification system designates the beneficial uses that 

each water body is expected to achieve (such as cold water biota, contact 

recreation, etc.). The numeric and/or narrative water quality criteria are 

the criteria deemed necessary by the State to support the beneficial use 

classification of each water body. The anti-degradation policy represents 

a three-tiered approach to maintain and protect various levels of water 

quality and uses. 

The Alaska Water Quality Standards (18 AAC 70.020(a)(2)) protect State 

marine waters for the following beneficial use classifications: aquaculture 

water supply, seafood processing water supply, industrial water supply, 

contact and secondary recreation, growth and propagation of fish, 

shellfish, other aquatic life, and wildlife, and harvesting for consumption 

of raw mollusks or other raw aquatic life. 

State marine waters covered under this general permit are tier 1 water 

bodies, therefore, water quality should be such that it results in no 

mortality and no significant growth or reproductive impairment of resident 

species. Coverage under this general NPDES permit cannot be authorized 

that would result in the water quality criteria being violated in the water 

body. The draft permit contains effluent limits that ensure that the 

existing beneficial uses for State marine waters covered under this general 

permit will be maintained. 

3. Water Quality Criteria 

The first step in developing water quality-based effluent limits is to 

determine the applicable water quality criteria. For Alaska, the State 

water quality standards are found at Title 18, Chapter 70 of the Alaska 

Administrative Code (18 AAC 70). The applicable criteria are determined 

based on the beneficial uses of the receiving water. The beneficial uses 

for the coastal areas of the Beaufort and Chukchi Seas are aquaculture 

water supply, seafood processing water supply, industrial water supply, 

contact and secondary recreation, growth and propagation of fish, 

shellfish, other aquatic life, and wildlife, and harvesting for consumption 

of raw mollusks or other raw aquatic life. For any given pollutant, 

different uses may have different criteria. To protect all beneficial uses, 

the permit limits are based on the most stringent of the water quality 

criteria applicable to those uses. 
14

When there are not numeric criteria, EPA must interpret the narrative 

criteria in order to evaluate reasonable potential. This can be 

accomplished in one of three methods: 

• Establish a permit limit using a calculated criterion using a 

proposed State water quality criterion, or an explicit State policy; 

• Establish permit limits on a case-by-case basis using EPA’s water 

quality criteria; or 

• Establish an indicator parameter. 

The most stringent numeric criteria based on the beneficial uses for the 

Beaufort and Chukchi Seas are summarized in Table C-1 of Appendix C. 

The most stringent narrative criteria based on the beneficial uses for the 

Beaufort and Chukchi Seas are also summarized in Appendix C. 

D. Proposed Effluent Limitations 

1. Statutory and Regulatory Basis for Limits. Sections 101, 301(b), 304, 

308, 401, 402, and 405 of the Clean Water Act (CWA) provide the basis 

for the effluent limitations and other conditions in the draft permit. The 

discharges are evaluated with respect to these sections of the CWA and 

the relevant National Pollutant Discharge Elimination System (NPDES) 

regulations to determine which conditions to include in the draft permit. 

2. Expression of Effluent Limitations. 

a. Continuous Discharges. The NPDES regulations at 40 CFR 

122.45(d) require that all effluent limitations, standards, and 

prohibitions of discharges from continuous sources at industrial 

facilities to be expressed, unless impracticable, as both maximum 

daily and monthly average values. 

b. Non-continuous Discharges. The federal regulations at 40 CFR 

122.45(e) allows non-continuous discharges to be described and 

limited considering the following factors, as appropriate: 

(1) Frequency of discharge; 

(2) Total mass of pollutant per batch discharge; 

(3) Maximum discharge rate of pollutants; and 

(4) Expression of limits using the appropriate measure (e.g., 

mass, concentration, etc.). 

3. Mass Versus Concentration Limits. The regulations at 40 CFR 

122.45(f)(1) require that all permit limits, standards, or prohibitions be 
15

expressed in terms of mass units (e.g., pounds, kilograms, grams) except 

under the following conditions: 

a. For pH, temperature, radiation, or other pollutants that cannot 

appropriately be addressed by mass limits; 

b. When applicable standards and limitations are expressed in terms 

of other units of measurement; or 

c. If in establishing technology-based permit limitations on a caseby-case basis limitations based on mass are infeasible because the 

mass or pollutant cannot be related to a measure of production. 

The limitations, however, just ensure that dilution will not be used 

as a substitute for treatment. 

 While the regulations require that limitations be expressed in terms of 

mass, a provision is included at 40 CFR 122.45(f)(2) that allows limits to 

be expressed in additional units (e.g., concentration units). Where limits 

are expressed in more than one unit, the permittee must comply with both. 

 The basis for expressing limitations in terms of concentration as well as 

mass is to encourage proper operation of treatment units. In the absence 

of concentration limits, a permittee would be able to increase its effluent 

concentration (i.e., reduce its level of treatment) during low flow periods 

and still meet its mass-based effluent limits. Therefore, concentration 

limits discourage the reduction in treatment efficiency during low flow 

periods, and require proper operation of treatment units at all times. 

4. The following provides the basis for the effluent limitations and 

requirements that are in the draft permit for all discharges: 

a. The proposed permit incorporates the state of Alaska’s water 

quality standard that requires waters of the state must not receive 

floating solids, debris, sludge, deposits, foam, scum, or other 

residues of any kind in concentrations causing nuisance, 

objectionable, or detrimental conditions or that make the water 

unfit or unsafe for the use. This standard is also being applied to 

discharges within federal waters to ensure compliance with the 

coastal zone management act. Operators have been subject to a no 

floating solids, visible foam, or oily waste requirement in previous 

permits issued by Region 10 and past practices have not resulted in 

violations. 

b. The proposed permit contains a provision that the discharge of 

surfactants, dispersants, and detergents must be minimized except 
16

as necessary to comply with the safety requirements of the 

Occupational Health and Safety Administration and the Mineral 

Management Service (MMS). The discharge of dispersants to 

marine waters in response to oil or other hazardous spills is not 

authorized by the permit. These products contain primarily 

nonconventional pollutants. This provision previously appeared in 

the permits for this industry located in the Beaufort Sea, Chuckchi 

Sea, Norton Sound, Bering Sea, and Cook Inlet. 

c. The proposed permit requires separation of area drains for 

washdown and rainfall that may be contaminated with oil and 

grease from those area drains that would not be contaminated. 

This will ensure that minimization of this conventional pollutant to 

waters of the U.S. This provision previously appeared in the 

permits for this industry located in Cook Inlet. 

d. The proposed permit prohibits discharges of the following 

pollutants: diesel oil, halogenated phenol compounds, trisodium 

nitrilotriacetic acid, sodium chromate, or sodium dichromate. The 

class of halogenated phenol compounds includes toxic pollutants, 

and sodium chromate and sodium dichromate contain chromium, 

also a toxic pollutant. Trisodium nitrilotriacetic acid is a 

nonconventional pollutant. The discharge of these compounds was 

previously prohibited in the permits for this industry located in the 

Beaufort Sea, Chuckchi Sea, Norton Sound, Bering Sea, and Cook 

Inlet. 

e. The proposed permit requires that any commingled discharges are 

subject to the most stringent effluent limitations for each 

individual discharge. If the individual discharge is not authorized, 

the commingled discharge is not authorized. This provision 

ensures that technology-based requirements are being adequately 

controlled rather than using dilution to meet the effluent 

limitations and that all parameters within the commingled 

discharge meet the water quality standards. 

f. The proposed permit requires the pH range of all discharges to be 

maintained between 6.5 and 8.5 standard units. This requirement 

is consistent with the Alaska water quality standards and has been 

previously required in permits for this industry in Cook Inlet. 

5. The following provides the basis for the effluent limitations and 

requirements that are in the draft permit for drilling fluids and drilling 

cuttings (discharge 001): 
17

a. Area Restrictions. 

The proposed permit is retaining the area restrictions of the current 

general permit. Area restrictions on this discharge are necessary to 

ensure no unreasonable degradation of the environment. In 

accordance with 40 CFR 125.123(c), the Director has prohibited 

these discharges because the Region has determined they may 

cause unreasonable degradation of the marine environment. 

EPA has extensively studied the nearshore zone of the Alaskan 

Beaufort Sea in several Ocean Discharge Criteria Evaluations 

(Tetra Tech, 1994, 2004; Jones & Stokes, 1983, 1984). These 

evaluations have clearly shown that these nearshore areas provide 

important feeding and migratory habitat for a large number of 

species including fish, waterfowl, and mammals. Further, these 

areas provide essential feeding and preferred habitat for species of 

major importance for subsistence and commercial fisheries. 

The proposed permit does not authorize discharges within 1000 

meters of the Stefansson Sound Boulder Patch as defined by 

Dunton et al. (1982). The “Patch” is a rare and unique biological 

community that is susceptible to adverse effects caused by 

discharged drilling muds and cuttings. 

The proposed permit restricts activity near Kasegaluk Lagoon and 

its barrier island system. Specifically discharge is prohibited 

within Kasegaluk Lagoon and in the waters within 3 miles of the 

following passes intensively used by the beluga whales: 

Kukpowruk Pass, Akunik Pass, Utukok Pass, Icy Cape Pass, and 

Alokiakatat Pass. This restriction is in accordance with the North 

Slope Borough’s Coastal Management Program (NSB, 1988). The 

North Slope Borough recognizes Kasegaluk Lagoon as a candidate 

Area Meriting Special Attention (AMSA) and imposes this 

restriction. 

Kasegaluk Lagoon extends for approximately 140 miles along the 

Chukchi Sea coast. About 90 miles of the lagoon is south of Icy 

Cape and the rest is north of Icy Cape. Kasegaluk Lagoon is 

located in State waters of the Chukchi Sea and provides important 

habitat for spotted seals and beluga whales. Beluga whales are 

known to feed, calve, and possibly molt in this lagoon (NSB, 1988; 

Frost and Lowry, 1993; Tetra Tech, 1994, 2004). Spotted seals 

also calve in Kasegaluk Lagoon (North Slope Borough, 1988). 

The lagoon also provides important feeding, migrating, and rearing 

areas for marine and anadromous fish, as well as migratory birds. 
18

Kasegaluk Lagoon, the barrier islands, and the nearshore waters 

seaward of the barrier islands are an important subsistence area for 

the villagers of Point Lay (North Slope Borough, 1988). 

Subsistence activities that occur seasonally in the Kasegaluk 

Lagoon candidate AMSA include egg gathering, waterfowl, 

hunting, sealing, fishing, walrus hunting, and whaling for belugas. 

This proposed permit and the Borough’s management program 

recognizes the importance of the area for marine mammals, 

seabirds, and subsistence activities. 

b. Seasonal Restrictions. 

The proposed permit is retaining the seasonal restriction of the 

current general permit. These restrictions are necessary to ensure 

the fate and transport of this discharge does not cause degradation 

to the environment and is consistent with the finding in several 

Ocean Discharge Criteria Evaluations (Tetra Tech, 1994, 2004; 

Jones & Stokes, 1983, 1984). 

c. Effluent Limitations. The proposed permit incorporates the 

effluent limitation required by the effluent limitation guidelines in 

40 CFR 435, Subpart A. The current general permit does not 

authorize the discharge of oil-based drilling muds (or drilling 

fluids) because EPA was developing national guidelines for this 

discharge. The proposed permit incorporates the ELGs 

requirements for non-aqueous drilling fluids that were promulgated 

January 22, 2001. Additional effluent limitations have been 

determined to be necessary for this discharge. The following 

provides the basis for these additional requirements. 

Suspended Particulate Phase (SPP) Toxicity. The proposed permit 

is retaining the effluent toxicity limit of a minimum of minimum 

96-hour LC50 of 30,000 ppm SPP on discharged water-based 

drilling fluids and drilling cuttings. This requirement is being 

added to non-aqueous drilling cuttings. This limit was designed to 

be a technology-based control on toxicity, as well as toxic and 

nonconventional pollutants. The 30,000 ppm SPP limitation is 

based on the Agency’s evaluation that it constitutes an 

economically and technically achievable level of performance and 

is both technologically feasible and economically achievable and 

reflects BAT level of control (USEPA, 1993) on a national basis. 

This provision previously appeared in the permits for this industry 

located in the Beaufort Sea, Chuckchi Sea, Norton Sound, Bering 
19

Sea, and Cook Inlet, as well as the 1992 general permit for the 

Western Gulf of Mexico (57 FR 54652, November 19, 1992). 

Total Aqueous Hydrocarbons (TAqH). The proposed permit has 

added effluent limitations for total aqueous hydrocarbons to ensure 

protection of Alaska water quality standards. The proposed limits 

are based on criteria end-of-pipe, but may be modified should the 

state of Alaska authorize a mixing zone for this parameter. 

Total Aromatic Hydrocarbons (TAH). The proposed permit has 

added effluent limitations for total aromatic hydrocarbons to 

ensure protection of Alaska water quality standards. The proposed 

limits are based on criteria end-of-pipe, but may be modified 

should the state of Alaska authorize a mixing zone for this 

parameter. 

Total Volume. The proposed permit is retaining the requirement to 

limit drilling discharges from no more than five wells at a single 

drilling site. However, this requirement has been updated to 

include specific information that would be necessary by the 

Director to allow the discharge from additional wells. In the past, 

this effluent limitation was included because it was the basis of the 

Ocean Discharge Criteria Evaluation (Tetra Tech, 1994). This 

Evaluation was updated in 2004 by Tetra Tech and retained the 

same basis for the analysis. Therefore, the new requirement 

includes the number of additional wells to be drilled, a technical 

analysis of additional impacts to the receiving waters from the 

additional wells, drilling fluid category and group for each well, 

and well information for each additional well, including well 

name, number, latitude, longitude, beginning drill date, and hole 

diameter. 

Stock Barite Monitoring (Table 1, footnote 5). The proposed 

permit is retaining the requirement for the analysis of a 

representative sample of stock barite once prior to drilling each 

well. If the same supply of stock barite is used to drill subsequent 

wells, the same analysis may be used for all wells. This 

requirement reduces the burden of monitoring for the operator 

while still providing the information necessary to ensure 

compliance with this permit. 

d. Flow Limitations. 

The proposed permit is retaining the flow limitations of the current 

general permit. The area of coverage includes water depths from 5 
20

to about 3,000 meters deep. Discharge rate limitations on total 

drilling fluids and drilling cuttings have been established in the 

ocean discharge criteria evaluation process in order to allow 

adequate dispersion of the discharges. The depth restriction is 

necessary because for any given discharge rate, the dilution of 

drilling fluids and drilling cuttings is not as great in shallow waters 

as in deeper waters. At any particular water depth, greater dilution 

close to the discharge point will be achieved with a lower 

discharge rate. These maximum rates will ensure that the water 

quality standards will not be exceeded at the edge of a 100-meter 

mixing zone (Tetra Tech, 2004). 

Previous permits have allowed the discharge of drilling fluids and 

drilling cuttings between 2 and 5 meters depth. However, 

computer modeling of the dispersion of the drilling fluids 

conducted for this permit within the depth range of 2 to 5 meters 

did not perform adequately (Tetra Tech, 2004). The maximum 

depth of drilling fluid accumulation for these cases was 10 to 20 

times greater than the water depth. Drilling fluid accumulations of 

this magnitude would effectively bury the drilling fluid outfall, 

making any calculation of dilution values meaningless. 

Accordingly, EPA is proposing zero discharge of drilling fluids 

and drilling cuttings in waters less than 5 meters depth. 

e. Environmental Monitoring. The proposed permit is retaining the 

environmental monitoring requirements for two areas which are of 

particular concern to Region 10: discharge of drilling fluids and 

drilling cuttings below-ice to water depths shallower than 20 

meters and within 10000 meters of an area of biological concern 

(i.e., a unique biological community or habitat). The Director has 

determined that controlled discharges to these areas, in accordance 

with 40 CFR 125.123(a) and the limitations and conditions in the 

draft permit, will not cause unreasonable degradation of the marine 

environment. Environmental monitoring is required to verify that 

discharges to these areas will not produce conditions in the future 

that would lead to unreasonable degradation. 

f. Mineral Oil Pills. The proposed permit is retaining the 

requirements for mineral oil pills. The Region has not obtained 

enough information regarding the impact of mineral pills on mud 

toxicity. This monitoring may be discontinued in the future should 

information show that the addition of the mineral pills does not 

impact mud toxicity. 
21

g. End-of-well Report. The proposed permit is retaining the 

requirement to submit an end-of-well report. However, 

requirements for the end-of-well report have been changed. 

In the current permit, the end-of-well report requires identification 

of the corresponding mud system and analysis for diesel oil, 

barium, cadmium, chromium, copper, mercury, zinc, lead, and 

toxicity. The report is to be submitted within 45 days following 

well completion. 

The proposed end-of-well report requires well name, number, 

latitude, longitude, beginning drill date, and hole diameter, well 

completion date, a precise chemical inventory of all constituents 

added downhole, including all drilling mud additives used to meet 

specific drilling requirements, the base mud type, the name and 

total amount of each constituent in the discharged mud, the total 

volumes of mud treated and added downhole, the maximum 

concentration of each constituent in the mud, the total volumes of 

mud discharged to surface waters, and the estimated amount of 

each constituent in the mud discharge to surface waters. The 

report is to be submitted with 90 days following well completion. 

The change in the end-of-well reporting requirements will better 

define the fate and transport of this discharge in the environment 

and the environmental impact of the discharge. The submittal date 

of the report was extended due to the increased requirements to 

allow the operator adequate time to complete the report. 

6. The following provides the basis for the effluent limitations and 

requirements that are in the draft permit for deck drainage (discharge 

002): 

a. Effluent Limitations. The proposed permit incorporates the 

effluent limitation required by the effluent limitation guidelines in 

40 CFR 435, Subpart A. 

b. Oil and Grease. The proposed permit is retaining the requirement 

that deck drainage contaminated with oil and grease must be 

processed through an oil-water separator prior to discharge. The 

requirement to sample the deck drainage discharge that is 

processed through the oil-water separator and tested for sheen has 

been retained, although it has been modified to state that sampling 

is to occur once per discharge event. In addition, the permit is 

proposing monitoring of total aqueous hydrocarbons (TAqH) and 
22

total aromatic hydrocarbons (TAH) to ensure compliance with 

Alaska water quality standards. 

7. The following provides the basis for the effluent limitations and 

requirements that are in the draft permit for sanitary wastes (discharge 

003): 

a. Effluent Limitations within Alaska Waters. The proposed permit 

incorporates the effluent limitations required by the effluent 

limitation guidelines in 40 CFR 435, Subpart A. Additional 

limitations have been proposed to ensure compliance with Alaska 

water quality standards and domestic water treatment 

requirements. These limits have been established under best 

professional judgment and the reasonable potential analysis for 

water quality-based effluent limitations provided in Appendix C. 

Best Professional Judgment. The state of Alaska has minimum 

treatment requirements for the discharge of domestic water (18 

AAC 72.050(a)(4)), which includes sanitary wastes. The State 

requires all domestic wastewater, which applies to sanitary waste 

(003), discharged into or onto waters of the State to meet 

secondary treatment. The State’s wastewater regulations provide 

effluent limitations for secondary treatment at 18 AAC 72.991(59) 

and summarized in Table 1. 

Table 1. Alaska Technology-based Effluent Limitations for 

Sanitary Wastes (003) 

Pollutant Parameter Duration Limitation

30-day average 30 mg/L 

BOD5 7-day average 45 mg/L 

24-hour average 60 mg/L 

30-day average 30 mg/L 

TSS 7-day average 45 mg/L 

24-hour average 60 mg/L 

pH in any measurement 6.0 - 9.0 

Water Quality-based Effluent Limits. Reasonable potential to 

violate Alaska water quality standards was determined for pH 

(M9IM and M10), fecal coliform bacteria (M9IM and M10), and 

total residual chlorine (M10). Therefore, water quality-based 

effluent limitations have been established for these parameters. 
23

The calculations for the water quality-based effluent limits are 

provided in Appendix C. 

b. Effluent Limitations beyond Alaska Waters. The proposed permit 

incorporates the effluent limitations required by the effluent 

limitation guidelines in 40 CFR 435, Subpart A. Additional 

limitations have been proposed to proper operation of the marine 

sanitation device. These limits have been established under best 

professional judgment. 

Best Professional Judgment. The EPA has federal regulations at 

40 CFR Part 140 that provide standards for marine sanitation 

devices (MSDs) that require effluents to contain a maximum of 

150 mg/L TSS, a maximum of 200/100 ml fecal coliform bacterial 

count, and no visible floating solids. 

c. Marine Sanitation Device (MSD). The proposed permit retains the 

requirement that the operator of a MSD to conduct annual testing 

of the unit to ensure that the unit is operating properly. The basis 

for this requirement is established through federal regulations at 40 

CFR 122.41(e) (Proper Operation and Maintenance). 

8. The basis for the effluent limitations and requirements that are in the draft 

permit for domestic wastes (discharge 004) are required by the effluent 

limitation guidelines in 40 CFR 435, Subpart A. 

9. The proposed permit retains the effluent limitation for no discharge of free 

oil from desalination unit wastes (discharge 005) based on best 

professional judgment (BPJ) of Best Practicable Control Technology 

Currently Available (BPT) controls for this discharge. BPT is based on 

the average of the best existing performance by plants of various sizes, 

ages, and unit processes within the industrial category or subcategory. 

BPJ-based effluent limits are technology-based limits derived on a caseby-case basis under Section 402(a)(1) of the Clean Water Act. BPJ limits 

are established in cases where ELGs are not available for, or do not 

regulate, a particular pollutant of concern. EPA has developed this BPJ 

effluent limitation in accordance with federal regulations 40 CFR 122.43, 

122.44, and 125.3. Compliance with the no free oil limitation is to be 

determined by visual observation for sheen on the receiving water using 

the static sheen test defined in Appendix 1 to 40 CFR Part 435, Subpart A. 

This discharge has been subject to this limitation in previous permits for 

this industry in Region 10 and past practices have not resulted in 

violations of this limit. 
24

10. The proposed permit retains the effluent limitation for no discharge of free 

oil from blowout preventer fluid (discharge 006) based on best 

professional judgment (BPJ) of Best Practicable Control Technology 

Currently Available (BPT) controls for this discharge. BPT is based on 

the average of the best existing performance by plants of various sizes, 

ages, and unit processes within the industrial category or subcategory. 

BPJ-based effluent limits are technology-based limits derived on a caseby-case basis under Section 402(a)(1) of the Clean Water Act. BPJ limits 

are established in cases where ELGs are not available for, or do not 

regulate, a particular pollutant of concern. EPA has developed this BPJ 

effluent limitation in accordance with federal regulations 40 CFR 122.43, 

122.44, and 125.3. Compliance with the no free oil limitation is to be 

determined by visual observation for sheen on the receiving water using 

the static sheen test defined in Appendix 1 to 40 CFR Part 435, Subpart A. 

This discharge has been subject to this limitation in previous permits for 

this industry in Region 10 and past practices have not resulted in 

violations of this limit. 

11. The proposed permit retains the effluent limitation for no discharge of free 

oil from boiler blowdown (discharge 007) based on best professional 

judgment (BPJ) of Best Practicable Control Technology Currently 

Available (BPT) controls for this discharge. BPT is based on the average 

of the best existing performance by plants of various sizes, ages, and unit 

processes within the industrial category or subcategory. BPJ-based 

effluent limits are technology-based limits derived on a case-by-case basis 

under Section 402(a)(1) of the Clean Water Act. BPJ limits are 

established in cases where ELGs are not available for, or do not regulate, a 

particular pollutant of concern. EPA has developed this BPJ effluent 

limitation in accordance with federal regulations 40 CFR 122.43, 122.44, 

and 125.3. Compliance with the no free oil limitation is to be determined 

by visual observation for sheen on the receiving water using the static 

sheen test defined in Appendix 1 to 40 CFR Part 435, Subpart A. This 

discharge has been subject to this limitation in previous permits for this 

industry in Region 10 and past practices have not resulted in violations of 

this limit. 

 

12. The proposed permit retains the effluent limitation for no discharge of free 

oil from fire control system test water (discharge 008) based on best 

professional judgment (BPJ) of Best Practicable Control Technology 

Currently Available (BPT) controls for this discharge. BPT is based on 

the average of the best existing performance by plants of various sizes, 

ages, and unit processes within the industrial category or subcategory. 

BPJ-based effluent limits are technology-based limits derived on a caseby-case basis under Section 402(a)(1) of the Clean Water Act. BPJ limits 

are established in cases where ELGs are not available for, or do not 
25

regulate, a particular pollutant of concern. EPA has developed this BPJ 

effluent limitation in accordance with federal regulations 40 CFR 122.43, 

122.44, and 125.3. Compliance with the no free oil limitation is to be 

determined by visual observation for sheen on the receiving water using 

the static sheen test defined in Appendix 1 to 40 CFR Part 435, Subpart A. 

This discharge has been subject to this limitation in previous permits for 

this industry in Region 10 and past practices have not resulted in 

violations of this limit. 

 

13. The following provides the basis for the effluent limitations and 

requirements that are in the draft permit for non-contact cooling water 

(discharge 009): 

a. Effluent limitations. The proposed permit retains the effluent 

limitation for no discharge of free oil based on best professional 

judgment (BPJ) of Best Practicable Control Technology Currently 

Available (BPT) controls for this discharge. BPT is based on the 

average of the best existing performance by plants of various sizes, 

ages, and unit processes within the industrial category or 

subcategory. BPJ-based effluent limits are technology-based 

limits derived on a case-by-case basis under Section 402(a)(1) of 

the Clean Water Act. BPJ limits are established in cases where 

ELGs are not available for, or do not regulate, a particular 

pollutant of concern. EPA has developed this BPJ effluent 

limitation in accordance with federal regulations 40 CFR 122.43, 

122.44, and 125.3. Compliance with the no free oil limitation is to 

be determined by visual observation for sheen on the receiving 

water using the static sheen test defined in Appendix 1 to 40 CFR 

Part 435, Subpart A. This discharge has been subject to this 

limitation in previous permits for this industry in Region 10 and 

past practices have not resulted in violations of this limit. 

b. Biocide and Chemical Inventory. The proposed permit retains the 

requirement for an annual inventory of the type and quantity of 

biocides and chemicals added to non-contact cooling water. The 

permit proposes that the report be submitted to EPA by March 1 of 

the following year. The basis for this requirement is to provide 

EPA with information regarding the specific chemicals added to 

discharge to ensure current permit limitations and requirements are 

protective of water quality.

14. The proposed permit retains the effluent limitation for no discharge of free 

oil from uncontaminated ballast water (discharge 010) based on best 

professional judgment (BPJ) of Best Practicable Control Technology 

Currently Available (BPT) controls for this discharge. BPT is based on 
26

the average of the best existing performance by plants of various sizes, 

ages, and unit processes within the industrial category or subcategory. 

BPJ-based effluent limits are technology-based limits derived on a caseby-case basis under Section 402(a)(1) of the Clean Water Act. BPJ limits 

are established in cases where ELGs are not available for, or do not 

regulate, a particular pollutant of concern. EPA has developed this BPJ 

effluent limitation in accordance with federal regulations 40 CFR 122.43, 

122.44, and 125.3. Compliance with the no free oil limitation is to be 

determined by visual observation for sheen on the receiving water using 

the static sheen test defined in Appendix 1 to 40 CFR Part 435, Subpart A. 

This discharge has been subject to this limitation in previous permits for 

this industry in Region 10 and past practices have not resulted in 

violations of this limit. 

15. The proposed permit retains the effluent limitation for no discharge of free 

oil from uncontaminated bilge water (discharge 011) based on best 

professional judgment (BPJ) of Best Practicable Control Technology 

Currently Available (BPT) controls for this discharge. BPT is based on 

the average of the best existing performance by plants of various sizes, 

ages, and unit processes within the industrial category or subcategory. 

BPJ-based effluent limits are technology-based limits derived on a caseby-case basis under Section 402(a)(1) of the Clean Water Act. BPJ limits 

are established in cases where ELGs are not available for, or do not 

regulate, a particular pollutant of concern. EPA has developed this BPJ 

effluent limitation in accordance with federal regulations 40 CFR 122.43, 

122.44, and 125.3. Compliance with the no free oil limitation is to be 

determined by visual observation for sheen on the receiving water using 

the static sheen test defined in Appendix 1 to 40 CFR Part 435, Subpart A. 

This discharge has been subject to this limitation in previous permits for 

this industry in Region 10 and past practices have not resulted in 

violations of this limit. 

 

16. The proposed permit retains the effluent limitation for no discharge of free 

oil from excess cement slurry (discharge 012) based on best professional 

judgment (BPJ) of Best Practicable Control Technology Currently 

Available (BPT) controls for this discharge. BPT is based on the average 

of the best existing performance by plants of various sizes, ages, and unit 

processes within the industrial category or subcategory. BPJ-based 

effluent limits are technology-based limits derived on a case-by-case basis 

under Section 402(a)(1) of the Clean Water Act. BPJ limits are 

established in cases where ELGs are not available for, or do not regulate, a 

particular pollutant of concern. EPA has developed this BPJ effluent 

limitation in accordance with federal regulations 40 CFR 122.43, 122.44, 

and 125.3. Compliance with the no free oil limitation is to be determined 

by visual observation for sheen on the receiving water using the static 
27

sheen test defined in Appendix 1 to 40 CFR Part 435, Subpart A. This 

discharge has been subject to this limitation in previous permits for this 

industry in Region 10 and past practices have not resulted in violations of 

this limit. 

 

17. The proposed permit retains the effluent limitation for no discharge of free 

oil from mud, cuttings, and cement at the seafloor (discharge 013) based 

on best professional judgment (BPJ) of Best Practicable Control 

Technology Currently Available (BPT) controls for this discharge. BPT is 

based on the average of the best existing performance by plants of various 

sizes, ages, and unit processes within the industrial category or 

subcategory. BPJ-based effluent limits are technology-based limits 

derived on a case-by-case basis under Section 402(a)(1) of the Clean 

Water Act. BPJ limits are established in cases where ELGs are not 

available for, or do not regulate, a particular pollutant of concern. EPA 

has developed this BPJ effluent limitation in accordance with federal 

regulations 40 CFR 122.43, 122.44, and 125.3. Compliance with the no 

free oil limitation is to be determined by visual observation for sheen on 

the receiving water using the static sheen test defined in Appendix 1 to 40 

CFR Part 435, Subpart A. This discharge has been subject to this 

limitation in previous permits for this industry in Region 10 and past 

practices have not resulted in violations of this limit. 

18. The following provides the basis for the effluent limitations and 

requirements that are in the draft permit for test fluids (discharge 014): 

a. Effluent limitations. 

Free Oil. The proposed permit retains the effluent limitation for no 

discharge of free oil based on best professional judgment (BPJ) of 

Best Practicable Control Technology Currently Available (BPT) 

controls for this discharge. BPT is based on the average of the best 

existing performance by plants of various sizes, ages, and unit 

processes within the industrial category or subcategory. BPJbased effluent limits are technology-based limits derived on a caseby-case basis under Section 402(a)(1) of the Clean Water Act. 

BPJ limits are established in cases where ELGs are not available 

for, or do not regulate, a particular pollutant of concern. EPA has 

developed this BPJ effluent limitation in accordance with federal 

regulations 40 CFR 122.43, 122.44, and 125.3. Compliance with 

the no free oil limitation is to be determined by visual observation 

for sheen on the receiving water using the static sheen test defined 

in Appendix 1 to 40 CFR Part 435, Subpart A. This discharge has 

been subject to this limitation in previous permits for this industry 
28

in Region 10 and past practices have not resulted in violations of 

this limit. 

Oil and Grease. The proposed permit retains the effluent limitation 

for oil and grease of 29 mg/L monthly average and 42 mg/L daily 

maximum. Although oil and grease is a conventional pollutant 

subject to BCT, it also serves as BAT (i.e., as an indicator of toxic 

pollutants for produced water. Specifically, the toxic pollutants 

that are controlled by limiting oil and grease include phenol, 

naphthalene, ethylbenzene, and toluene (USEPA, 1993). EPA has 

determined that it is not technically feasible to control these toxic 

pollutants individually so that the limitation on oil and grease 

controls discharge of these pollutants in produced water at the 

BAT level (USEPA, 1993). 

The promulgated BAT for oil and grease in produced water as 29 

mg/L monthly average and 42 mg/L daily maximum based upon 

the improved operating performance of gas flotation technology of 

test fluids and produced water, Region 10 has determined that it is 

reasonable to apply the produced water provisions to test fluids. 

This discharge has been subject to this limitation in previous 

permits for this industry in Region 10 and past practices have not 

resulted in violations of this limit. 

pH. The proposed permit retains the effluent limitation for pH of 

6.5 to 8.5 standard units. The pH of discharged test fluids (which 

may have a substantially different pH from that of the ambient 

receiving water) has been has been established based on best 

professional judgment (BPJ) of Best Practicable Control 

Technology Currently Available (BPT) controls for this discharge. 

This limitation will ensure that pH changes greater than 0.2 

standard units will not occur beyond the edge of the 100-meter 

mixing zone (40 CFR 125.121(c)). This discharge has been 

subject to this limitation in previous permits for this industry in 

Region 10 and past practices have not resulted in violations of this 

limit. 

III. PROPOSED MONITORING REQUIREMENTS 

A. Basis for Effluent Monitoring. 

1. Section 308 of the Clean Water Act and federal regulation 40 CFR 

122.44(i) require effluent monitoring in NPDES permits to determine 

compliance with effluent limitations. The draft permit only requires 
29

monitoring of discharges that are authorized by the coverage letter to each 

individual applicant. 

2. Monitoring Frequency. Monitoring frequencies are based on the nature 

and effect of the pollutant, as well as a determination of the minimum 

sampling necessary to adequately monitor the facility’s performance. 

3. Sample Type. 

a. Estimated. Since the volume of the authorized discharges, except 

the sanitary discharge, is minimal and is not expected to present a 

significant risk to the environment, EPA has proposed in the draft 

permit that these discharge volumes be estimated rather than 

measured to provide relief from additional administrative burden. 

b. Visual. 

(1) Free Oil. Compliance with the free oil limitation will be 

monitored by year-round use of the Static Sheen Test daily 

and before bulk discharges. Region 10 requires use of the 

Static Sheen Test because visual observation of the 

discharge for sheen upon the receiving water will not 

prevent violations of the standard. This test is also 

appropriate for the harsh weather and extended periods of 

darkness common in Alaska. 

(2) Floating solids, garbage and foam. The only way to 

adequately measure a discharge for this parameter is to 

conduct a visual analysis of the receiving waterbody to 

determine the presence or absence of floating solids, 

garbage and foam. 

c. Grab. Grab samples are appropriate for parameters (i.e., pH, fecal 

coliform bacteria, and total residual chlorine) that are likely to 

change with storage or for parameters (i.e., BOD5 and TSS) that 

are not likely to change over time. It is also more appropriate to 

collect grab samples for whole effluent toxicity analysis of the 

deck drainage discharge because it is known that the potential for 

toxicity is greatest during a significant rainfall or snowmelt. 

Additionally, the deck drainage discharge is precipitation related 

and may not last long enough to collect a composite sample. 

B. Proposed Effluent Monitoring. 

1. The following presents the proposed effluent monitoring requirements for 

the draft permit for all discharges. 
30

a. The proposed permit retains the requirement that monitoring for 

the facility is not required if is it not staffed. The permittee must 

provide EPA and ADEC written notification that the facility is no 

longer staffed 30 days prior to terminating monitoring 

requirements. This industry has been subject to this monitoring 

requirement in previous permits in Region 10. 

b. The proposed permit requires that all effluent samples must be 

collected from the effluent stream of each discharge after the last 

treatment unit prior to discharge into the receiving waters. This 

requirement is necessary to assure compliance with the Clean 

Water Act and the limits of the permit; therefore, the basis for this 

requirement is 40 CFR 122.43(a) and 122.44. This industry has 

been subject to this monitoring requirement in previous permits in 

Region 10. 

c. The proposed permit requires pH in all discharges to be monitored 

monthly, unless otherwise indicated in this permit. This industry 

has been subject to this monitoring requirement in previous 

permits in Region 10. 

d. The proposed permit requires visual monitoring to be conducted of 

the receiving water surface in the vicinity of the outfall(s) during 

daylight at a time of maximum estimated or measured discharge. 

This industry has been subject to this monitoring requirement in 

previous permits in Region 10. 

e. The proposed permit requires measurement or estimation of 

discharge flow or volume for each discharge to allow EPA to know 

the amount of contaminants are entering the environment to ensure 

that water quality is maintained. 

2. In addition to monitoring for limited parameters in the draft permit for 

drilling fluids and drilling cuttings (discharge 001), the proposed permit is 

retaining the environmental monitoring requirements. Environmental 

monitoring is required in two areas which are of particular concern to 

Region 10: discharge of drilling fluids and cuttings below-ice to water 

depths shallower than 20 meters and within 1000 meters of an area of 

biological concern (i.e., a unique biological community or habitat). EPA 

has determined that controlled discharges to these areas, in accordance 

with 40 CFR 125.123(a) and the limitations and conditions in the draft 

permit, will not cause unreasonable degradation of the marine 

environment. Environmental monitoring is required to verify that 

discharges to these areas will not produce conditions in the future that 

would lead to unreasonable degradation. 
31

3. In addition to monitoring for limited parameters in the draft permit for 

deck drainage (discharge 002), the proposed permit requires samples for 

the deck drainage discharge to be collected from the oil/water separator 

effluent and tested for sheen. This discharge has been subject to this 

monitoring requirement in previous permits for this industry in Region 10 

IV. SPECIAL CONDITIONS 

A. Quality Assurance Plan (QAP). 

 The federal regulation at 40 CFR 122.41(e) requires the permittee to develop a 

Quality Assurance Plan to ensure that the monitoring data submitted is accurate 

and to explain data anomalies if they occur. The permittee is required to develop 

a Quality Assurance Plan within 90 days of the effective date of the final permit. 

The Quality Assurance Plan must consist of standard operating procedures the 

permittee must follow for collecting, handling, storing and shipping samples, 

laboratory analysis, and data reporting. 

B. Best Management Practices (BMP) Plan. 

 Section 402 of the Clean Water Act and federal regulations 40 CFR 122.44(k)(2) 

and (3) authorize EPA to require best management practices, or BMPs, in NPDES 

permits. BMPs are measures for controlling the generation of pollutants and their 

release to waterways. These measures are important tools for waste minimization 

and pollution prevention. 

 The draft permit requires operators to have a BMP Plan that incorporates 

practices to achieve the objectives and specific requirements in the permit. The 

BMP plan must be revised as new practices are developed for the facility. 

C. Mud Plan. 

The proposed permit is retaining the requirement for a mud plan. The basis for 

the mud plan requirement is Section 308(a)(A) of the Act, which provides that 

EPA may require the permittee to establish and maintain records and/or reports 

that will assist the Region to determine compliance with other requirements and 

effluent limitations of the permit. The mud plan is one component of the Best 

Management Practices Plan. The mud plan requirement is also based upon the 

Pollution Prevention Act and its policy of prevention, reduction, recycling, and 

treatment or wastes (PPA Section 102(b)) through measures that include process 

modification, materials substitution, and improvement of management (PPA 

Section 107(b)(3)). 

The goal of requiring development of a mud plan is to ensure that personnel onsite are knowledgeable about the information needed and the methods required to 
32

formulate the mud/additive systems in order to meet the effluent toxicity limit. 

The intent of the mud plan is a written guide to planning for and using a 

mud/additive system in compliance with the permit. To date, Alaskan operators 

have demonstrated that thorough planning and evaluation of mud/additive 

systems with respect to possible cumulative toxicity does consistently result in 

discharge of muds that are less toxic than the required limitation. 

The mud plan is intended to demonstrate that the discharged mud/additive system 

for the well in question will meet the effluent limitation based on the following 

decision criteria: 

• Estimates of worst case cumulative discharge toxicity (either calculated or 

actual toxicity test results); 

• Estimates of toxicity of discharged mud when a mineral oil pill has been 

used; and 

• Use of less toxic alternatives, where possible. 

The mud plan is also required to include a clearly stated procedure for dealing 

with situations in which additives not originally planned for are needed at the last 

minute. This procedure should enable drilling and mud personnel to determine 

whether an additive or mud component may be added to the circulating mud 

system without significant effect upon the discharge toxicity. Criteria for 

reaching this type of last minute additive decision is required to be clearly 

specified in the mud plan. 

V. OTHER LEGAL REQUIREMENTS 

A. State Certification Requirements. 

 Since this permit authorizes discharges to Alaska State waters, section 401 of the 

Clean Water Act requires EPA to seek state certification before issuing a final 

permit. As a result of the certification, the state may require more stringent 

permit conditions to ensure that the permit complies with water quality standards. 

B. Standard Permit Provisions. 

 Sections III, V and VI of the draft permit contain standard regulatory language 

that must be included in all NPDES permits. Because they are regulations, they 

cannot be challenged in the context of an NPDES permit action. The standard 

regulatory language covers requirements such as monitoring, recording, reporting 

requirements, compliance responsibilities, and other general requirements. 
33

C. Endangered Species Act of 1973. 

 Section 7 of the Endangered Species Act requires Federal agencies to consult with 

the National Marine Fisheries Service (NMFS) and the U. S. Fish and Wildlife 

Service (USFWS) if their actions could beneficially or adversely affect any 

threatened or endangered species. Under the NEPA process (see Part VII.H, 

below), NMFS and USFWS have determined that the proposed action is not likely 

to adversely affect threatened or endangered species. Therefore, EPA has 

determined that the issuance of this permit will not affect any of the threatened or 

endangered species in the vicinity of the discharge and no further consultation is 

required. This fact sheet and the draft permit will be submitted to NMFS and the 

USFWS for review during the public notice period. 

D. Essential Fish Habitat. 

 The Magnuson-Stevens Fishery Conservation and Management Act 

(January 21, 1999) requires EPA to consult with the National Marine Fisheries 

Service (NMFS) when a proposed discharge has the potential to adversely affect 

(reduce quality and/or quantity of) EFH. Under the NEPA process (see Part 

VII.H, below), NMFS had determined that the proposed action is not likely to 

affect any EFH species. Therefore, EPA has determined that the reissuance of 

this permit will not affect any EFH species; therefore, no consultation is required. 

This fact sheet and the draft permit will be submitted to NMFS for review during 

the public notice period. 

E. Permit Expiration. 

 Section 402(1)(B) of the Clean Water Act require that NPDES permits are issued 

for a period not to exceed five years, therefore, this permit will expire five years 

from the effective date of the permit. 

F. Ocean Discharge Criteria. 

 Section 403 of the Clean Water Act requires that an NPDES permit for a 

discharge into marine waters located seaward of the inner boundary of the 

territorial seas (i.e., state and federal offshore waters) be issued in accordance 

with guidelines for determining the potential degradation of the marine 

environment. These guidelines, referred to as the Ocean Discharge Criteria (40 

CFR Part 125, Subpart M), and section 403 of the Clean Water Act are intended 

to “prevent unreasonable degradation of the marine environment and to authorize 

imposition of effluent limitations, including a prohibition of discharge, if 

necessary, to ensure this goal.” (49 FR 65942, October 3, 1980) 

 When EPA determines that the discharge will cause unreasonable degradation, an 

NPDES permit may not be issued. If a definitive determination of no 
34

unreasonable degradation cannot be made because of insufficient information, 

EPA must then determine whether a discharge will cause irreparable harm to the 

marine environment and whether there are reasonable alternatives to on-site 

disposal. To assess the probability of irreparable harm, EPA is required to make a 

determination that the discharger, operating under appropriate permit conditions, 

will not cause permanent and significant harm to the environment during a 

monitoring period in which additional information is gathered. If data gathered 

through monitoring indicate that continued discharge may cause unreasonable 

degradation, the discharge shall be halted or additional permit limitations 

established. 

The Region has determined that discharges occurring under the proposed permit, 

which incorporates the above prohibitions, will not cause unreasonable 

degradation as long as the limitations, requirements, and conditions of the 

proposed permit are met. 

G. Coastal Zone Management Act (CZMA). 

 The applicant has certified that the activities authorized by the draft permit are 

consistent with the Alaska Coastal Management Plan. Pursuant to 

40 CFR Part 122.49(d), requirements of the State coastal zone management 

program must be satisfied before the permit may be issued. 

H. Oil Spill Requirements. 

Section 311 of the Clean Water Act prohibits the discharge of oil and hazardous 

materials in harmful quantities. Routine discharges specifically controlled by the 

permit are excluded from the provisions of Section 311. However, this permit 

does not preclude the institution of legal action or relieve permittees from any 

responsibilities, liabilities, or penalties for other unauthorized discharges of oil 

and hazardous materials, which are covered by Section 311. 
35

VI. REFERENCES 

ADEC, 2001. Water Quality Standards As amended through September 28, 2001. Alaska 

Department of Environmental Conservation, 18 AAC 70. 

ADEC, 1999. Wastewater Disposal As amended through April 1, 1999. Alaska Department of 

Environmental Conservation, 18 AAC 72. 

Dunton, K., E. Reimnitz, and S. Schonberg. 1982. An Arctic Kelp Community in the Alaskan 

Beaufort Sea. Arctic 35(4): 465-484. 

Frost, K.J., and L.F. Lowry. 1993. Distribution and Abundance of Beluga Whales and Spotted 

Seals in the Chukchi Sea, Including Recent Findings at Kasegaluk Lagoon. In: Alaska 

OCS Region Fifth Information Transfer Meeting Conference Proceedings. U.S. Dept. of 

the Interior, Minerals Management Service. OCS Study MMS 93-0043. 

Jones & Stokes Associates. 1983. Final ocean discharge criteria evaluation, Diapir Field, OCS 

lease sale 71. Prepared for U.S. Environmental Protection Agency, Region 10. March 

1983. 

Jones & Stokes Associates. 1984. Final ocean discharge criteria evaluation, Diapir Field, OCS 

lease sale 87 and state lease sales 39, 43, and 43a. Prepared for U.S. Environmental 

Protection Agency, Region 10, July 24, 1984. 

NSB. 1988. North Slope Borough Coastal Management Program. 

Tetra Tech, Inc., 1994. Ocean discharge criteria evaluation for Arctic state and federal waters. 

Prepared for the U.S. Environmental Protection Agency. July 1994. 

Tetra Tech, Inc. 2004. Draft Ocean Discharge Criteria Evaluation for Area of Coverage Under 

the Arctic NPDES General Permit for Oil and Gas Exploration. Prepared for the U.S. 

Environmental Protection Agency. March 2004. 

. USEPA, 1991. Technical Support Document for Water Quality-based Toxics Control. U.S. 

Environmental Protection Agency, Office of Water, EPA\505\2-90-001. March, 1991. 

USEPA, 1993. Development Document for Effluent Limitations Guidelines and New Source 

Performance Standards for the Offshore Subcategory of the Oil and Gas Extraction Pont 

Source Category (Final). U.S. Environmental Protection Agency, Office of Water, EPA 

821-R-93-003. January, 1993. 

USEPA, 2000. Development Document for Final Effluent Limitations Guidelines and Standards 

for Synthetic-Based Drilling Fluids and other Non-Aqueous Drilling Fluids in the Oil 

and Gas Extraction Point Source Category. U.S. Environmental Protection Agency, 

Office of Water, EPA-821-B-00-013. December 2000. 
Page A-1

APPENDIX A

Description of Discharges 

There are fourteen (14) different discharges associated with the oil and gas extraction industry 

conducting offshore exploration. The draft permit proposes that only the discharge of waste 

streams that were clearly identified in the permit application process will be authorized by the 

general permit. 

Discharge 001 Drilling Fluids and Cuttings. Drilling fluids are the circulating fluids used in the 

rotary drilling of wells to clean and condition the hole, counterbalance formation 

pressure and transport drill cuttings to the surface. Drill cuttings are the particles 

generated by drilling into subsurface geologic formations and carried to the 

surface with the drilling fluid. 

Discharge 002 Deck Drainage. Deck drainage refers to any waste resulting from platform 

washing, deck washing, spillage, rainwater, and runoff from curbs, gutters, and 

drains, including drip pans and wash areas. This could also include pollutants, 

such as detergents used in platform and equipment washing, oil, grease, and 

drilling fluids spilled during normal operations. 

Discharge 003 Sanitary Waste. Sanitary waste is human body waste discharged from toilets and 

urinals. 

Discharge 004 Domestic Waste. Domestic waste (gray water) refers to materials discharged 

from sinks, showers, laundries, safety showers, eyewash stations, and galleys. 

Gray water can include kitchen solids, detergents, cleansers, oil and grease. 

Discharge 005 Desalination Unit Waste. Desalination unit waste is wastewater associated with 

the process of creating freshwater from seawater. 

Discharge 006 Blowout Preventer Fluid (006). Blowout preventer fluid is fluid used to actuate 

hydraulic equipment on the blowout preventer. 

Discharge 007 Boiler Blowdown. Boiler blowdown is the discharge of water and minerals 

drained from boiler drums to minimize solids build-up in the boiler. Although 

boiler blowdown discharges are not planned or likely to occur, they may occur 

intermittently. 

Discharge 008 Fire Control System Test Water. Fire control system test water is sea water that is 

released during the training of personnel in fire protection, and the testing and 

maintenance of fire protection equipment on the platform. 

Discharge 009 Non-contact Cooling Water. Non-contact cooling water is sea water that is used 

for non-contact, once-through cooling of various pieces of machinery on the 

platform. 
Page A-2

Discharge 010 Uncontaminated Ballast Water. Ballast waster is seawater added or removed to 

maintain the proper ballast floater level and ship draft. 

Discharge 011 Bilge Water. Bilge water is water which collects in the lower internal parts of the 

drilling vessel hull. 

Discharge 012 Excess Cement Slurry. Excess cement slurry will result from equipment 

washdown after cementing operations. Excess cement slurry is discharged 

intermittently while drilling, depending on drilling, casing, and testing program 

and problems. 

Discharge 013 Mud, Cuttings, Cement at Seafloor. Muds, cuttings, and cement at the seafloor 

are materials discharge at the surface of the ocean floor in the early phases of 

drilling operations, before the well casing is set, and during well abandonment 

and plugging. 

Discharge 014 Test Fluids. Test fluids are discharges that occur if hydrocarbons located during 

exploratory drilling are tested for formation pressure and content. This would 

consist of fluids sent downhole during testing, along with water from the 

formation. 
 Page B-1

APPENDIX B

Maps 

Figure B-1. Active MMS Leases in the Beaufort Sea
 Page B-2

Figure B-2. Arctic General Permit Area of Coverage
 Page C-1

APPENDIX C

Basis for Water Quality-based Effluent Limitations 

Table C-1. Water Quality Criteria Applicable to the General Permit Discharges within Alaska 

Waters 

CRITERIA

DISCHARGE POLLUTANT PARAMETER

Acute Chronic

Cadmium (total recoverable) 43 μg/l 9.3 μg/l 

Mercury (total recoverable) 2.1 μg/l 0.0025 μg/l 

Total aqueous hydrocarbons (TAqH) 15 μg/l5

Drilling Fluids and Drilling 

Cuttings (001) 

Total aromatic hydrocarbons (TAH) 10 μg/l6

Total aqueous hydrocarbons (TAqH) 15 μg/l5

Deck Drainage (002) 

Total aromatic hydrocarbons (TAH) 10 μg/l6

Total Residual Chlorine 2.0 μg/l 

14 FC/100 ml2 Sanitary Waste (003) 

Fecal Coliform Bacteria1

43 FC/100 ml3

Total aqueous hydrocarbons (TAqH) 15 μg/l5

Domestic Waste (004) 

Total aromatic hydrocarbons (TAH) 10 μg/l6

Total aqueous hydrocarbons (TAqH) 15 μg/l5

Excess Cement Slurry (012)

Total aromatic hydrocarbons (TAH) 10 μg/l6

All pH 6.5 - 8.54

Footnotes: 

1 Based on the median most probable number (MPN) from a 5-tube decimal dilution test. 

2 Based on any one sample. 

3 Based on #10% of the samples. 

4 May not vary more than 0.1 pH unit from natural conditions. 

5 As determined by summing the results of EPA Method 602 (plus Xylenes) to quantify monoaromatic 

hydrocarbons to measure TAH and EPA Method 610 to quantify polynuclear aromatic hydrocarbons. 

6 As determined by EPA Method 602 (plus Xylenes) to quantify monoaromatic hydrocarbons. 

 The most stringent narrative criteria based on the beneficial uses for the Beaufort 

and Chukchi Seas are summarized in the following paragraphs: 

1. Residues. Floating solids, debris, sludge, deposits, foam, scum, or other 

residues may not, alone or in combination with other substances or wastes, 

make the water unfit or unsafe for the use; cause acute or chronic problem 

levels as determined by bioassay or other appropriate methods; cause a 
 Page C-2

film, sheen, or discoloration on the surface of the water or adjoining 

shorelines; cause leaching of toxic or deleterious substances; or cause a 

sludge solid, or emulsion to be deposited beneath or upon the surface of 

the water, within the water column, on the bottom, or upon adjoining 

shorelines. 

2. Petroleum Hydrocarbons, Oils and Grease. Surface waters, floor of the 

waterbody, and adjoining shorelines must be virtually free from floating 

oil, film, sheen, or discoloration. 

3. Odor or Taste to Fish or Aquatic Organisms. Substances may not be 

present in concentrations that individually or in combination impart 

undesirable odor or taste to fish or other aquatic organisms based on 

bioassay or organoleptic tests. 

B. Reasonable Potential Evaluation 

1. Determination of Reasonable Potential 

 To determine if there is “reasonable potential” to cause or contribute to an 

exceedance of water quality criteria for a given pollutant (and therefore 

whether a water quality-based effluent limit is needed), for each pollutant 

present in a discharge, EPA compares the maximum projected receiving 

water concentration to the criteria for that pollutant. If the projected 

receiving water concentration exceeds the criteria, there is “reasonable 

potential,” and a limit must be included in the permit. EPA uses the 

recommendations in Chapter 3 of the TSD (EPA, 1991) to conduct this 

“reasonable potential” analysis. 

2. Reasonable Potential Evaluation Procedure with Numeric Criteria. 

a. Because the effluent discharges are to a marine environment, the 

appropriate steady-state mixing model to calculate the minimum 

dilution at critical conditions is: 

 Cd x Vd = (Ce x Ve) + (Cu x Vd), 

 where, Cd is the projected receiving water concentration, Vd is the 

volume of the receiving water used for mixing (i.e., the mixing 

zone dilution), Ce is the maximum effluent concentration, Ve is the 

estimated volume of effluent discharged, and Cu is the existing 

receiving water concentration prior to effluent discharge. 

 The predicted receiving water concentration (Cd) can be calculated 

by rearranging the basic mass balance equation, as follows: 
 Page C-3

 Cd = (Ce x Ve ÷ Vd) + Cu, 

 where the ratio of the effluent volume to the receiving water 

volume (Ve ÷ Vd) is the dilution ratio. The dilution ratio is 

determined from computer modeling performed by ADEC. 

 If Cu is equal to 0, the equation becomes 

 Cd = Ce x Ve ÷ Vd. 

b. The criterion is then compared to the maximum projected 

receiving water concentration to determine the need for a waterquality-based effluent limitation (WQBEL). If the projected 

receiving water concentration is equal to or greater than the 

criterion, then a WQBEL for that pollutant must be incorporated 

into the permit. 

 The exception is for BOD, nutrients, and bacteria where the WLAs 

are directly applied as the WQBEL (i.e., the acute WLA is the 

maximum daily limit and the chronic WLA is the average monthly 

limit). In this case, the projected receiving water concentration 

must be greater than the criterion before a WQBEL is necessary 

for that pollutant. 

3. Reasonable Potential Evaluation Procedure with Narrative Criteria. 

 The EPA must establish levels that are protective of the narrative criteria 

(40 CFR 122.44(d)(1)(vi)) in the absence of State numeric criteria and 

when there is reasonable potential for the discharge to cause or contribute 

to an excursion that results in the violation of the narrative water quality 

standard. In order to determine this, EPA must use the best information 

available to characterize the conditions of the receiving water body and 

the point source discharge (effluent). 

4. Reasonable Potential Analysis. 

a. Total Residual Chlorine. In order to determine reasonable 

potential, the technology-based effluent limitation (minimum 

residual chlorine) is used as the maximum projected effluent 

concentration and 0 is assumed for the background concentration. 

Additionally, the permit proposes a dilution ratio of 500:1 (volume 

receiving water:volume effluent). The analysis (see calculations in 

Appendix C) indicates that WQBELs are necessary for the sanitary 

discharge. 

b. Fecal Coliform Bacteria. 
 Page C-4

 In order to determine reasonable potential, the technology-based 

effluent limitation is used as the maximum projected effluent 

concentration and 0 is assumed for the background concentration. 

Both water quality criteria are evaluated directly against the 

technology-based effluent limit because the proposed sample 

frequency is once per month. Since the permit does not proposed a 

dilution ratio for fecal coliform, the analysis (see calculations in 

Appendix C) indicates that WQBELs are necessary for the sanitary 

discharge. 

c. pH. The technology-based effluent range of pH is 6.0 - 9.0 

standard units applies only to the sanitary discharge. Since the 

water quality standards require a pH range of 6.5 - 8.5 and the 

permit does not proposed a dilution ratio for pH in the sanitary 

discharge, EPA has determined that there is reasonable potential 

for this discharge. Additionally, EPA has determined that there is 

reasonable potential for the other authorized discharges to violate 

this water quality standard. 

d. Residues. The domestic waste discharge has a technology-based 

effluent limitation that prohibits the discharge floating solids, 

garbage and foam. All other discharges are required to contain no 

free oil. Since the water quality standards prohibit the discharge 

floating solids, debris, sludge, deposits, foam, scum, or other 

residues of any kind in concentrations causing nuisance, 

objectionable, or detrimental conditions or that make the water 

unfit or unsafe for the use, Region 10 has determined that there is 

reasonable potential for these discharges to violate this water 

quality standard. 

C. Water Quality-based Permit Limit Derivation 

 Once EPA has determined that a water quality-based limit is required for a 

pollutant, the first step in developing the permit limit is development of a 

wasteload allocation (WLA) for the pollutant. A WLA is the concentration (or 

loading) of a pollutant that may be discharged without causing or contributing to 

an exceedence of water quality standards in the receiving water. The WLAs and 

permit limits are derived based on guidance in the TSD (EPA, 1991). The WLAs 

are then converted to long-term average concentrations (LTAs) and compared. 

The most stringent LTA concentration for each parameter is converted to effluent 

limits. 

1. Total Residual Chlorine. 
 Page C-5

 Since the Alaska water quality criteria for total residual chlorine is 

reported as a single value (i.e., 2 μg/L), the TSD (EPA, 1991) 

recommends deriving the wasteload allocation (WLA) from the single 

criterion as the chronic WLA. In the absence of data to evaluate the true 

variability of the effluent, EPA has used a value of 0.6 for the coefficient 

of variation (CV) in the statistical calculations for WQBELs. A CV of 0.6 

is a conservative estimate that assumes relatively high variability in the 

final permit limit. 

 The resulting WQBELs (see calculations in Appendix C) indicate effluent 

maximum concentrations while the technology-based limit indicates a 

minimum control level. Consequently, the WQBELs are the more 

stringent effluent limits and are applied to this discharge. 

2. pH. 

 The draft permit incorporates the more stringent water quality-based pH 

range of 6.5 to 8.5 standard units. 

3. Residues. 

 The draft permit prohibits any discharge of floating solids, debris, sludge, 

deposits, foam, scum, or other residues of any kind in concentrations 

causing nuisance, objectionable, or detrimental conditions or that make 

the water unfit or unsafe for the use. 

4. Fecal Coliform Bacteria. 

 The draft permit incorporates the more stringent water quality-based 

criteria of 14 FC/100 mL in any sample and 43 FC/100 mL in #10% of the 

samples. 
 Page D-1

APPENDIX D

Calculations 

I. TOTAL RESIDUAL CHLORINE 

A. Reasonable Potential Calculations 

Table D-1. Reasonable Potential Analysis for Total Residual Chlorine 

Aquatic Life - Chronic Nomenclature Value Units

criterion 0.002 mg/L 

projected receiving water concentration 

Cd = (Ce ÷ dilution ratio) +Cu

Cd 0.002 mg/L 

maximum effluent concentration Ce = TBEL Ce 1.0 mg/L 

Technology-based effluent limit TBEL 1.0 mg/L 

dilution ratio 500:1 

background concentration Cu 0 mg/L

 The projected receiving water concentration (Cd) is equal to the chronic criterion 

for aquatic life, thus, there is reasonable potential to violate this water quality 

standard. 

B. Wasteload Allocation Calculations 

Table D-2. Waste Load Allocation for Total Residual Chlorine 

Aquatic Life - Chronic Nomenclature Value Units

wasteload allocation 

WLA = Ce = [Cd - Cu] x dilution ration 

WLAc 1.0 mg/L 

chronic criterion Cd 0.002 mg/L 

dilution ratio 500:1 

background concentration Cu 0 mg/L
 Page D-2

C. Water Quality-based Effluent Limitation (WQBEL) Calculations 

Table D-3. Water Quality-based Effluent Limits for Total Residual Chlorine 

Aquatic Life Nomenclature Value Units

maximum daily limit 

MDL = LTA@exp[z99σ - 0.5σ2

] 

MDL 1.6 mg/L 

average monthly limit 

AML = LTA@exp[z95σn - 0.5σn

2

] 

AML 0.8 mg/L 

average annual effluent flow Qe 0.00202 mgd 

long term average 

LTAc= WLAc@exp[0.5σ4

2

 - z99σ4] 

LTA 0.53 

chronic wasteload allocation WLAc 1.0 

z-score (99th percentile) z99 2.326 

z-score (95th percentile) z95 1.645 

coefficient of variation CV 0.6 

popular variance 

σ2

 = ln(CV2+1) 

σ2

 0.31 

standard deviation 

σ = (σ2

)

0.5

σ 0.55 

number of samples required per month n 4 

σn

2

 = ln[(CV2 ÷ n)+1] σn

2

 0.086 

σn = (σn

2

)

0.5 σn 0.29 
 Page D-3

II. FECAL COLIFORM BACTERIA 

A. Reasonable Potential Calculations 

Table D-4. Reasonable Potential Analysis for Fecal Coliform Bacteria 

Aquatic Life Nomenclature Value Units

criterion 14 FC/100 mL 

projected receiving water concentration 

Cd = (Ce ÷ dilution ration) +Cu

Cd 200 FC/100 mL 

maximum effluent concentration Ce = TBEL Ce 200 FC/100 mL 

Technology-based effluent limit TBEL 200 FC/100 mL 

dilution ratio 0 

background concentration Cu 0 FC/100 mL 

criterion (in #10% of samples) 43 FC/100 mL 

projected receiving water concentration 

Cd = (Ce ÷ dilution ration) +Cu

Cd 200 FC/100 mL 

maximum effluent concentration Ce = TBEL Ce 200 FC/100 mL 

Technology-based effluent limit TBEL 200 FC/100 mL 

dilution ratio 0 

background concentration Cu 0 FC/100 mL 

 The projected receiving water concentration (Cd) is less than or equal to the 

criteria for aquatic life, thus, there is not reasonable potential to violate this water 

quality standard. 

B. Wasteload Allocation Calculations 

 N/A 

C. Water Quality-based Effluent Limitation (WQBEL) Calculations 

 N/A