## Final Ocean Discharge Cr iteria 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 219 th St. SW, Suite 550 Mountlake Terrace, WA 98043[page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
1-i 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............................................................... 3-13ODCE for Arctic NPDES General Permit 1/24/06
1-ii 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 Tr ansport, 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................................................................................. 4-29ODCE for Arctic NPDES General Permit 1/24/06
1-iii TABLE OF CONTENTS (cont.)

4.6.4 Critical Areas or Habitats............................................................................. 4-30 4.6.5 Effects Analysis ........................................................................................... 4-32
4.7 THREATENED AND ENDA NGERED 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 ........................................................................................... 6-1ODCE for Arctic NPDES General Permit 1/24/06
1-iv 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 DISCHARG ES ON HARVEST QUANTITY... 7-2
7.4 EFFECTS OF DRILLING DISCHARG ES 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 ENFORCE ABLE 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 ....................................................................................................... 11-1ODCE for Arctic NPDES General Permit 1/24/06
1-v LIST OF FIGURES

Figure 1-1. Arctic NPDES Genera l Permit Area of Coverage ............................................ A-1 Figure 3-1. Approximate pattern of initial particle deposition ............................................ A-2 Figure 4-1. Major Trophic Pathways (F ood Web) in the Arctic Regions ........................... A-3

LIST OF TABLES

Table 2-1. Eight Generic Dr illing Mud Compositions .........................................................B-1
Table 2-2. Metals Concen trations in Barite Used in Drilling Fluids ....................................B-2 Table 2-3. Concentration of Organic Po llutants 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 Sedime nt Trace Metal Alterations fr om 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 S ynthetic-Based Drilling Fluids (LC 50 s ) .......................B-9 Table 3-4. OOC Model Input Pa rameters 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 Mixi ng Zone for Open-Water Discharge ........................................................................................................B-12 Table 3-7. Summary of OOC Mode l Results for Below-Ice Discharg e 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 Re sults 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 Bi oaccumulation Study Results .......................................B-17 Table 3-13. Depuration of Metals Bioaccumula ted 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 Li sted Species Occurring Within the Area of Coverage......B-26 Table 4-7. Summary of Critical Habitat Designations for ESA Li sted 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 fr om Barite and Drilling Fluids .............................B-28
Table 9-2. Soluble and Solids Metals Concentrations........................................................B-28ODCE for Arctic NPDES General Permit 1/24/06
1-vi LIST OF TABLES (cont.)

Table 9-3. Comparison of Drilli ng 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 Drilli ng 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 Drilli ng Mud Predicted Dissolved Metal Concentrations (at Mixing Zone Boundary) to Marine Water Quality Criteria Case 3: Dredged material partition coeffi cients 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 coeffi cients are used to estimate dissolved metal concentrations in drilling cuttings..................................................................B-34 Table 9-9. Comparison of Sanita ry 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 Perm it for Oil and Gas Exploration in the ArcticODCE for Arctic NPDES General Permit 1/24/06
1-vii 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
EC 40 Effect concentration to 40% test organisms
EC 50 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
LC 50 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 ShelfODCE for Arctic NPDES General Permit 1/24/06
1-viii 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 fluidODCE for Arctic NPDES General Permit 1/24/06
1-ix 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/m 3 kilograms per cubic meter
km kilometers
km 2 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

m 2 square meters mg/cm 2 milligram per square centimeter mgd million gallons per day mg/kg milligram per kilogram mg/L milligrams per liter

m 3 /h cubic meters per hour
mi miles
m/km meters per kilometer
mL milliliter

mm millimeterODCE for Arctic NPDES General Permit 1/24/06
1-x 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 volumeODCE for Arctic NPDES General Permit 1/24/06
1-1 

## 1.0 INTRODUCTION

1.1. PURPOSE OF EVALUATION

The U.S. Environmental Protection Agency (U SEPA) intends to issue a National Pollutant Discharge Elimination System (NPDES) general pe rmit for effluent discharges associated with oil and gas exploration ac tivities in the Outer Continental Sh elf (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 cont iguous 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 di scharges to be issued in compliance with USEPA’s Ocean Discharge Criteria for preventi ng unreasonable degradation of ocean waters. The purpose of this Ocean Discharge Criteria Eval uation (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 de gradation that must be made prior to permit issuance. Unreasonable degradation of the marine enviro nment is defined (40 CFR 125.121[e]) as follows:

• Significant adverse changes in ecosystem diversity, productiv ity, and stability of the biological community within the area of discharge and surrounding biological communities;

• Threat to human health through direct expos ure to pollutants or through consumption of exposed aquatic organisms; or

• Loss of aesthetic, recreational, scientific, or economic valu es, which are unreasonable in
relation to the benefit deri ved from the discharge.

This determination is to be made based on c onsideration of the follo wing 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 polluta nts 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 f unction of the ecosystem, such as those important for the food chain;ODCE for Arctic NPDES General Permit 1/24/06
1-2 4. The importance of the receiving wate r area to the surrounding biological community, including the presence of sp awning sites, nursery/forage areas, migratory pathways, or areas necessary for ot her 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, nation al 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 recr eational and commercial fish ing, including finfishing and shellfishing;

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

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

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

If the Regional Administrator determines that the discharge will not cause unreasonable degradation of the marine environment, an NP DES permit may be issued. If the Regional Administrator determines that the discharge wi ll cause unreasonable degrad ation of the marine environment, an NPDES permit may not be issued.

If the Regional Administrator has insufficient info rmation 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 alternat ives 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 und esirable 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 categor ized into exploratory, developmental, and production operations. Explorator y drilling operations are conducte d from drill barges, jack-up rigs, drilling ships, or semi-submersible rigs to identify the location of producing formations.ODCE for Arctic NPDES General Permit 1/24/06
1-3 Development operations are conducte d on platforms from which multip le wells are dr illed after a commercially exploitable reserve has been iden tified. Production operations ensue during and after developm ental drilling.

This document evaluates the impacts of waste di scharges as provided fo r by the Arctic NPDES general permit proposed for offshore oil and gas e xploration 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 ar ea of coverage includes the following: federal waters of the Beaufort Sea and Chukchi Sea, H ope 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 basi ns (Figure 1-1). The “state waters” under consideration in this ODCE typi cally extend from the coastal base line 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 Res ources (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 in sure that all areas potentially leased during the term of this general permit will be covered. While the MMS planning basins (i.e., Be aufort Sea, Chukchi Sea, Hope Basin and Norton Basin Planning Area s) 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 gui dance 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 concer ning certain topics. The information presented here is a synthesis of these documents, along wi th 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 Beaufo rt 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 ar ea (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.ODCE for Arctic NPDES General Permit 1/24/06
1-4 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 milli on acres (ac)] of the Beaufort Sea Planning Area and contiguous State waters (Figure 1-1).

Five biologically sensitive areas have been iden tified in the Beaufort Sea, all of which are
located shoreward of the 10-m isobath. These ar eas are the Salt Marshes; Harrison Bay/Colville River Delta; Thetis Island; Simpson Lagoon; an d 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 th e western portion of the proposed sale area consisting of 26 whole or partial blocks , approximately 138,000 ac, for protection of
Barrow subsistence-use zone s 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, fo r protection of the Native Village of
Kaktovik’s traditional known s ubsistence-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 ar ea that the state of Alaska has deferred in recent state sales for the protecti on of bowhead whales and environment.

Additionally, ADNR has identified the following areas and time periods as sensitive areas that require special consideration wh en proposing leas ing activities:

• the Boulder Patch in Stef ansson 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 pol ar bear denning areas, including the Leffingwell Cabin national historic site located on Flaxman Island;

• the Jones Island Group (Pingok, Spy, and Leav itt Islands) and Pole Island are known polar bear denning sites, November-April;

• the Sagavanirktok River delta, January-December; and

• Howe Island supports a snow goos e nesting colony, May-August.ODCE for Arctic NPDES General Permit 1/24/06
1-5 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 (Figur e 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 curr ent 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 partic ular lease blocks that may be available for sale, the entire MMS Chukchi Sea Pl anning 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) offshor e 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 th e MMS proposed final 5-Y ear 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 Stat e waters (Figure 1-1); however, for the term of the proposed permit MMS will likely only consid er leasing the areas identified in the MMS 2002 planning area (Special Interest Sale). There are no current le ase 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 pa rticular 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 contiguou s 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 Inte rest Sale). There are no cu rrent lease sales in the Norton Sound by either MMS or ADNR. Additionally, A DNR has not proposed any lease offerings inODCE for Arctic NPDES General Permit 1/24/06
1-6 the Norton Sound. Since the area of MMS Special In terest Sale does not id entify 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 Covera ge extends from the Cape Prince of Wales southward to Yukon Delta (63°N). It extends about 593 km (320 nm i) 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 larg est run of king salmon. Approxima tely one-third of this delta region comprises the Clarence Rhode National Wildli fe 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 wi ll be drilled from a moveable platform resting on the seafloor when i ce is not present in these water bodies. An ice or gravel island could be constructed to allow drilling to continue dur ing 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 shor t period in the summer months. Also, icebreakers could provide support in the vi cinity of the drilling rig to control sea ice (MMS, 2002).

1.3. OVERVIEW OF REPORT

The evaluation focuses on sources, fate, and pot ential effects of expl oratory drilling rig discharges on various groups of aquatic life. The types and projected quantit ies 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 disc harged constituents in relation to influential receiving water properties, including water dept h, ice coverage, currents, wind, and waves. Section 3.0 also provides estimates of the vertical and horizontal coverage and depos ition of the discharges. This information is needed to assess aquatic toxici ty and food chain accumulation questions, and the probability of burying benthic infaunal inverteb rates 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 effect s 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. Sec tion 6.0 provides information on tr ibal resources other thanODCE for Arctic NPDES General Permit 1/24/06
1-7 subsistence that may be affected by this action. Commercial fisheries ar e discussed in Section 7.0 and coastal zone management is discusse d in Section 8.0. Sec tion 9.0 discusses the compliance of expected explorator y drilling discharges with Alas ka water quality criteria and Section 10.0 summarizes the findings of this report. All figures fo r this evaluation are presented in Appendix A; tables are found in Appendix B.ODCE for Arctic NPDES General Permit 1/24/06
1-8 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
2-1 

## 2.0 COMPOSITION AND QUANTITIES OF MATERIALS DISCHARGED

2.1. TYPES OF DISCHARGES FROM DRILLING ACTIVITIES

This document evaluates the impacts of waste di scharges as provided fo r by the Arctic NPDES general permit proposed for offshore oil and gas e xploration (i.e., drilling activities). Production activities and produced water discha rges are not discussed in this document because they are not authorized by this permit.

Oil and gas drilling generates a wi de range of waste materials re lated 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 drilli ng 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 volu mes and amounts of pollutants. The major waste streams from drilling operations ar e drilling fluids, also called drilling mud, and drilling cuttings due to their volume and co mposition. A discussion of drilling fluids and cuttings is provided in Section 2.2. The remain ing waste streams are miscellaneous waste. These are waste streams that are generated in re latively small volume and contain low pollutant levels, yet significant enough to be of regulatory concern. Miscellaneous wastes generated from drilling operations are deck draina ge, domestic and sanitary wast e. 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 dr illing “mud”) circulates down the bore hole and back to the surface, carrying drill cuttings (earth en material) with it. The drill cuttings are separated from the drilling fluid on the explorat ory 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 trans port them to the surface; (3) counterbalance formation pressure to prevent form ation fluids (i.e. oil, gas, and water) from entering the well prematurely, a nd (4) prevent the open (uncas ed) wellbore from caving in (Berger and Anderson, 1992; Souders, 1998). Drilling fluids are specif ically formulated to meet the physical and chemical conditions of each partic ular well site. Therefor e, different properties may be required of the drilling fluid, dependi ng upon the drilling condi tions. For example, a higher-density fluid may be needed in high-pres sure zones, and a more temperature-resistant fluid may be desired in high-temperature conditions.ODCE for Arctic NPDES General Permit 1/24/06
2-2 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 incr eases the viscosity and alters th e 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 Amer ican Petroleum Institute (API) environmental guidance document “Waste Ma nagement in Exploration and Production Operations,” (API E5) considers the three genera l categories of drilling fluid (muds) to be waterbased, oil-based, and synthetic-based. Synthetic-ba sed muds are used as substitutes for oil-based muds, but also may be an advantageous replacem ent for water-based muds in some situations. Water-based muds are used most frequently. Th e 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 th ey are less expensive to use sin ce the resultant drilling waste can be discharged onsite provided these wastes pass regulatory requirement s (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-ba sed muds are not able to supply sufficient lubricity to avoid stic king of the drill pipe. Reactivity with clay shale can cause the
destabilization of the wellbore. In these cases , oil-based and syntheti c 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 th an water-based muds. Th is higher cost, which includes the added burden of removing the oil fr om 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 oi l-based muds can avoid the pore -clogging that may occur with
water-based muds. Also oil-based muds are used when drilling th rough reactive (or high pressure) shales, high-angle dir ectional drilling, and drilling in deep water. These situations encountered while drilling can slow down the dri lling rate, increase drilling costs or even be impossible if water-based muds are used. In cas es when oil-based muds are necessary, the upper section of a well generally is dr illed with water-based muds and the conversion is made to oilbased mud when the situation requires it. It is pr edicted 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 discha rged this may not be the case.

Since about 1990, the oil and gas extraction indus try 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, s ynthetic paraffins, ethers , linear alkylbenzenes, and others. Other oleaginous materials have also be en developed for this purpose, such as enhanced mineral oils and non-synthetic paraffins. Indus try developed synthetic-based fl uids with these synthetic and non-synthetic oleaginous material s as the base fluid to prov ide the drilling performance
characteristics of traditional oi l-based fluids based on diesel and mineral oil, but with the potential for lower environmental impact and gr eater worker safety through lower toxicity, elimination of polyaromatic hydrocarbons (PAH), fa ster biodegradability, lower bioaccumulationODCE for Arctic NPDES General Permit 1/24/06
2-3 potential and in some drilling situations decreased drilling waste volume (FR 66086, December 16, 1996).

Drilling muds typically have seve ral additives. The following is a list of the more significant
additives:

• Weighting materials, primarily barite (bariu m sulfate), may be used to increase the density of the mud in order to equilibr ate the pressure between the wellbore and formation when drilling through particul arly pressurized zones. Hematite (Fe 2 O 3 ) sometimes is used as a weighting agent in oil-based muds (Souders, 1998).

• Corrosion inhibitors such as iron oxide, alum inum bisulfate, zinc carbonate, and zinc chromate protect pipes and other metall ic components from acidic compounds
encountered in the formation.

• Dispersants, including iron lignosulfonates, br eak 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, chloropheno ls, or formaldehydes, kill bacteria that may produce toxic hydrogen sulfide gas.

• Fluid loss reducers include star ch and organic polymers a nd limit the loss of drilling mud to under-pressurized or high-perm eability 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 dr illed into a previously undrilled or noncommercial trap to test for the presence of a new hydrocar bon accumulation. A delineation well is a well that
is drilled at a distance from a di scovery well to determine the physic al 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 dril led 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 histor ical data, the MMS FEIS for Lease Sales 186, 195,ODCE for Arctic NPDES General Permit 1/24/06
2-4 and 202 (MMS, 2003, 2004a), and the ADNR 1999 Lease Sale (ADNR, 1999). Activities on the leases could extend over a pe riod of 25 to 40 years.

Based on historical explorati on well data since 1960 (ADNR, 1999) , 31 wells have been drilled
in federal waters of the Beaufort Sea and 401 ha ve 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, Fi gure 5.3) that 5-10 wells will be drilled each year from exploration activities in the Nort h Slope of which only a small fr action, maybe 1-2 wells, will be drilled offshore. The percent of these wells th at has resulted in disc overy is 13.2 percent. Therefore, it is estimated that 10 exploration we lls and one delineation we ll will be drilled in State waters under this permit.

Exploratory drilling for Lease Sa le 186 is expected to contin ue 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 approximat ely six exploration wells and
six delineation wells will be drilled during the permit period.

Exploratory drilling for the areas covered under L ease 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 delinea tion 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 L ease 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 peri od (MMS 2003). It is expected th at one exploration well and one
delineation well will be dril led 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 Cove rage 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 sa les exclude nearshore tracts, th e 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 l eases. It is expected that appr oximately 2 exploration wells and 2
delineation wells will be drilled at Lease Sale 19 3 and no exploration or de lineation wells will be
drilled at Lease Sale 203 duri ng the period of this permit.ODCE for Arctic NPDES General Permit 1/24/06
2-5 2.2.1.3. Hope Basin

It is expected that no explorati on or delineation wells will be dr illed during the period of this permit based on the information provided in th e MMS FEIS for the OCS Oil and Gas Leasing Program (2002-2007).

2.2.1.4. Norton Sound

It is expected that no explorati on or delineation wells will be dr illed during the period of this permit based on the information provided in th e 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 cutt ings. Additionally, the permit incorporates an end-of -pipe whole effluent toxicity limit of a minimum 96-hour LC 50 of 30,000 parts per million (ppm) suspended particulate phase (SPP) on discharged drilling fluids. This limit is a technology-based control on to xicity, as well as t oxic and nonconventional pollutants. The 30,000 ppm SPP limitation is ba sed upon the Agency's evaluation that it constitutes an economically a nd technically achieva ble level of performance and is both technologically feasible and economically achievable and refl ects 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 flui ds (drilling muds) have water or a water miscible fluid as the continuous phase and the suspending medium fo r 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 cour se of drilling a single hole when encountering
different formations. Table 2-1 shows the form ulations for eight generic muds; concentration ranges account for the variab ility in the environment (e.g., drilling formations).

Synthetic-based drilling fluids ar e a subset of non-aqueous drilling fluids, i.e., those which have a water-immiscible fluid, such as an oleaginou s (oil-like) material as the continuous phase. Synthetic-based drilling fluids incl ude vegetable esters, poly alpha ol efins, internal olefins, linear alpha olefins, synthetic paraffins, ethers, line ar alkyl benzenes, and others (USEPA, 1999b). Based on data provided by the American Petrol eum Institute, typical synthetic-based drilling fluids have a formulation consisting of 47 per cent by weight synthetic- based drilling fluid, 33 percent solids, and 20 percent water (Bake r-Hughes Inteq as cited in USEPA, 1999b).ODCE for Arctic NPDES General Permit 1/24/06
2-6 2.2.3.1. Barite

Barite is the principal weighting agent of bot h water-based drilling muds and synthetic-based drilling fluids. Barite is mostly barium sulfate, which is 59 percen t barium by weight. Barite is a naturally occurring mineral, is readily available and inexpensiv e, 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 ch emical inertness. As shown in Table 2-1,
barite concentrations in dril ling 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 adhe ring 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 regula tions 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 per cent copper and 7 percent lead), and drill collar dope (which can contain 35 percent zinc, 20 pe rcent 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 synthe tic-based drilling fluids. Among the additives used in large e nough quantities to result in sign ificant 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-c ontaining lignosulfonate), incident al contamination from pipe dope, and possibly to differences in la boratory analyses and sample sources.

2.2.3.4. Spotting Compounds

Spotting compounds are used to help free stuck dril l strings. Some of these (e.g., vegetable oil or fatty acid glycerol) are easily broken down in the environment. The most effective and,ODCE for Arctic NPDES General Permit 1/24/06
2-7 consequently, most frequently used compounds are oil-based. The discharge of muds and cuttings contaminated by diesel oil or diesel oi l 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 poten tially toxic organic pollutants to drilling muds to which they are
added. These data show that th e concentration of or ganic pollutants in the drilling muds is roughly proportional to the amount of mineral o il 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, alkyl ated biphenyls, and alkylated dibenzothiaphenes were detected in one or more of the oils. Napht halene is the only one of the individual compounds detected fo r which Federal marine water quality criteria exist.

2.2.3.5. Lubricants

Lubricants are added to the dr illing mud when high torque c onditions are encountered on the drill string. These can be vegeta ble, paraffinic, or asphaltic-based compounds such as Soltex. When needed, these lubricants are used to tr eat the entire mud syst em [roughly 32,000 liters (L) or 8,453 gallons (gal)] and are discharged into re ceiving 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 sy stem. 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 m ud system is treated with zinc
carbonate to achieve mud concentrations of zi nc between 1.5 and 5.5 kilograms per cubic meter (kg/m 3 ) [0.01-0.05 pounds per gallon (lb/gal)], resu lting in 240-940 kg (520-2,080 lb) of zinc in the mud system. The zinc sulfide and unreactiv e zinc compounds are discharged with the drilling mud into the environment, thus c ontributing to the overall loading of zinc.ODCE for Arctic NPDES General Permit 1/24/06
2-8 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 fibe rs, 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) pe r barrel (bbl) of mud, which results in 220 to 2,200 kg (1,000 to 10,000 lb) of additives to the sy stem. 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 additi ves 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 characteristic s 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 de pths greater than 10,000 ft . Washing of drilling cuttings has some effect on the physical properti es, but has no noticeable affects on the metals content. Available conventional, metals, and organic water qualit y 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 drill ing operations is quite variable. Drilling fluids are sepa rated from the drill cuttings on the exploratory vessel and reused in the wellbore. The volume of rock cuttings pr oduced from drilling is primarily a function of the depth of the well and the diameter of the well bore. It has been estimated that between 0.2 bbl and 2.0 bbl (8.4 and 84.0 gal) of total drilling wast e are produced for each vertical foot drilled (USEPA, 1987).

Each exploratory and delineation well in the Beau fort 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 a nd delineation well in the Chukchi Sea Area of Coverage. There are no estimates of discharg e rates for the Hope Basin and Norton Sound Area of Coverage since it is not predicted that any we lls 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.ODCE for Arctic NPDES General Permit 1/24/06
2-9 It is estimated that 90 percent of the wells dr illed will use water-based drilling fluids. For drilling depths of 7,000 ft, it is assumed that 80 pe rcent of the water-based drilling muds will be recycled and the remaining “spent mud” will be di scharged 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 assume d to use synthetic-based drilling fluids (USEPA, 1999b). Synthetic-based drilling fl uids are prohibited from bei ng 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 opera tions and discharged only as a contaminant attached to drill cuttin gs, 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 Ta ble 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 to tal 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 to tal 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 opera ting leases in the Hope Basin, no estimate is available for the amount of drilling muds and cutt ings expected to be discharged in the Hope Basin or contiguous State waters due to fu ture exploratory oil and gas exploration.ODCE for Arctic NPDES General Permit 1/24/06
2-10 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 cu ttings expected to be discharged in Norton Sound or contiguous State waters due to fu ture exploratory oil and gas exploration.

2.2.6. Summary

There are three general categorie s of drilling fluid (muds) water-b ased, 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 mi neral oil, but result in lower volumes of waste discharge. Synthetic-based flui ds provide the drilling performan ce characteristics of oil-based fluids, but have less environmen tal 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 w ills will be drilled in the Chukchi Sea Area of Coverage. No exploration wells or delinea tion 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 dril ling 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 c onditions encountered dur ing the drilling.

It is estimated that 8,085 bbl dril ling muds and 50,160 bbl drill cutti ngs will be discharged in the Beaufort Sea Area of Coverage and 2,260 bbl dr illing 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 ar e a relatively small but significant category of waste from the oil and gas extraction industry are de ck drainage, sanitary
waste and domestic waste. Because of their natu re, these waste streams are the most likely to contain constituents of concern. The following paragraphs provide a discussion of each of these discharges.ODCE for Arctic NPDES General Permit 1/24/06
2-11 2.3.1. Deck Drainage

Deck drainage refers to any waste resulting from platform wa shing, deck washing, spillage, rainwater, and runoff from curbs, gutters, and drai ns, including drip pans and wash areas. This could also include pollutants, su ch as detergents used in platform and equipment washing, oil, grease, and drilling fluids spil led during normal operations.

Deck drainage occurs when water from rainfall or from equipment cleaning comes in contact with oil-coated surfaces; the wate r 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 chemical s used in drilling operations may be present in deck drainages. The chemicals may include dril ling fluids, ethylene glyc ol, lubricants, fuels, biocides, surfactants, detergents, corrosion inhibi tors, cleaners, solvents, paint cleaners, bleach, dispersants, coagulants, and any other chemical used in the da ily operations of the facility (Dalton, Dalton, & Newport, 1985).

2.3.1.1. Characteristics of Untr eated 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 pollu tant 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, temperat ure, oil density, oil viscosity and wax content, and oil droplet size (USEPA, 1993a). A typical facil ity is equipped with drip pans and gutters to collect deck and drilling flow drai nage. The drainage is collected in a sump where the water and oil are separated by a gravity separation proces s. Oil in the sump tank is recovered and transferred to shore via pipeline or reinjected to the formati on. 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 construc ted of large diameter pi pes containing internal
baffled sections and an outlet at the bottom. Du ring the period of no flow, oil will rise to the quiescent areas below the underside of inclined baffled plates wh ere it coalesces. Due to the differences in specific gravity, oil floats upward th rough oil risers from baffle to baffle. The oil
is collected at the surfac e and removed by a submerged pump. These pumps operate intermittently and will move the separated oil to a sump tank.ODCE for Arctic NPDES General Permit 1/24/06
2-12 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 discha rged in a very short period of time. Deck drainage is a concern pa rticularly in areas with high precipitation; however, the low Arctic temperatures prevent hi gh volumes of deck drainage since operations occur mainly in the winter months and precipita tion drainage is expected to occur only during summer months. Under the current permit, disc harge quantities varied from 12 to 78,193 gallons per day (gpd) (Individual discharge values are provid ed in Table 2-6.). While it is expected that only small quantities (less than 300 gpd) of deck drainage w ould occur during the effective period of this permit, it is possible that hi gher quantities (~ 75,000 gpd) may occur as shown by past discharges. This general permit requires th e facilities to report tota l quantity discharged rather than flow rates to provide a more adequa te future analysis of deck drainage quantities discharged.

2.3.2. Sanitary and Domestic Waste

While some platforms discharge sanitary and do mestic wastes separately, many combine these waste streams prior to discharge. Therefore, th is 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. Do mestic waste (gray water) refers to materials discharged from sinks, showers, la undries, 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 pa per and cardboard which must be disposed of properly. Domestic waste is sometimes reused to make drilling m ud rather than being discharged directly into receiving waters.

2.3.2.1. Characteristics of Sanita ry and Domestic Wastes

The concentration of sanitary wastes vari es widely with time, occupancy, platform characteristics and operational situation. Polluta nts of concern in untreated sanitary waste include biochemical oxygen demand (BOD), total su spended solids (TSS), coliform, and residual chlorine. Typical concentrations of these pollu tants 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 domes tic waste include BOD and TSS. Typical concentrations of these pollutants in treat ed effluent are 195 and 140 mg/L, respectively (USEPA, 1993a).ODCE for Arctic NPDES General Permit 1/24/06
2-13 2.3.2.2. Control and Treatment Technology

There are two alternatives to handl ing of sanitary wastes from offs hore 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 physica l/chemical and biological.

It is often necessary to utilize m acerators with domestic wastes to prevent the release of floating solids. Chlorination is not necessary since thes e wastes do not contain coliforms. Additionally, the permit prohibits the discha rge of foam and garbage.

The NPDES permit controls these discharges as follows:

• BOD and TSS must have an average mont hly 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 concentrati ons must be less than 1.0 mg/L in Federal waters and in State waters when a mixing zone is author ized, 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 va ries widely with time, occupancy, platform characteristics, and operational situation. Discharge of sanitary waste from an Alaska n 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 b een 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 discha rge rates of 868 to 75,150 gpd have been reported for Arctic Alaska platforms based on discharg e monitoring reports. Individual discharge values are provided in Table 2-6. It is estimated that di scharges of sanitary and domestic wastes will be less than 6,000 gpd per rig for the e ffective period of this permit.ODCE for Arctic NPDES General Permit 1/24/06
2-14 2.4. MINOR DISCHARGES

The term “minor” discharges is used to describe all point sources originating from offshore oil and gas drilling operations other th an 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 locate d on the sea floor or on the drilling platform and is designed to maintain the pressure in the we ll that cannot be controlled by the drilling mud. Fluid on the blowout preventer may be discha rged 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 ba sis. 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 gl ycol and water). The volume of blowout preventer fluid discharge has been estimated to range from 67 to 314 bbl/day (USE PA, 1993a). It is estimated that discharges of blowout preven ter 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 revers e osmosis units, used in creating freshwater from seawater. The
concentrate is similar to sea water in chemi cal composition; however, anions and cations concentrations are higher. The general permit pr ohibits the discharge of free oil in this waste

stream.

Discharge from desalination units may vary greatly depending on the freshwat er needs of the rig. Under the current permit, discharge quanti ties varied from 174 to 140,000 gpd based on discharge monitoring reports; indi vidual discharge values are pr ovided 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 wast es 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 repo rt total quantity discha rged rather than flow rates to provide a more adequate future analysis of desa lination unit waste qua ntities discharged.ODCE for Arctic NPDES General Permit 1/24/06
2-15 2.4.3. Fire Control System Test Water

Fire control system test water is sea water that is re leased during the training of personnel in fire protection, and the testing and ma intenance of fire protection e quipment on the platform. This test water may be treated with a biocide. R ecommended dosages are very situation-dependent and can vary from 1.0 to as high as 1,200 ppm. Th ere are, however, little or no quantitative data on biocide concentrations in this discharge. Ther e 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 disc harge values are provided in Ta ble 2-6. Therefore, it is estimated that discharges of fire control sy stem test water will be less than 360 gpd when discharged. This general permit re quires the facilities to report total quantity discharged rather than flow rates to provide a more adequate futu re 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. R ecommended dosages are very situation-dependent and can vary from 1.0 to as high as 1,200 ppm. Th ere are, however, little or no quantitative data on biocide concentrations in this discharge.

The volume of non-contact cooling water require d 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 monito ring reports. Individual discharge values are provided in Table 2-6. Therefore, it is estimat ed 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 rath er than flow rates to provide a more adequate future analysis of non-contact cooling water quantities discha rged. The general pe rmit also requires the permittee to provide an annual inventory of the ty pe (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 ma intain 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 th rough the oil/water separation process or with aODCE for Arctic NPDES General Permit 1/24/06
2-16 small amount of dissolved aromatic constituen ts through molecular diffu sion at the oil-water surface prior to discharge. The general permit pr ohibits the discharge of any materials that may
cause a visible sheen of oil.

Under the current permit, discharge quant ities varied from 40 to 2,254,000 gpd based on discharge monitoring reports; indi vidual discharge values are provi ded 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 wh ich 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 usua lly treated with an oil/water se parator to remove oil prior to discharge. The general permit pr ohibits the discharge of any mate rials that may cause a visible
sheen of oil.

Two reported values of bilge water discharges from an Al askan 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 fac ilities to report total quantity discharged rather than fl ow rates to provide a more ade quate 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 genera l permit prohibits the discharge of free oil in
this waste stream.

Under the current permit, discharge quanti ties varied from 174 to 140,000 gpd based on discharge monitoring reports; indi vidual discharge values are provi ded 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 blowdo wn quantities discharged.

2.4.8. Test Fluids

Test fluids are discharges that occur if hydrocarbons located during explor atory drilling are tested for formation pressure and content, usua lly at the completion of drilling. This would consist of fluids sent downhole during testi ng, along with water from the formation. TheODCE for Arctic NPDES General Permit 1/24/06
2-17 discharge may consist of formation water, vegetabl e or mineral oil, natural gas, formation sands, any added acids or chemicals, or any combin ation 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 su bstantial 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 mont hly 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 di scharged 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 to tal 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 equipm ent 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 disc harge values are provided in Ta ble 2-6. Therefore, it is estimated that discharged quantities under this ge neral permit will be highly variable, but will not be greater than 10,000 gpd when discharge. This general permit requires th e 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 di scharge at the surface of the ocean floor in the early phases of drilling operati ons, 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 discharg e from an Alaskan offshore oil and gas facility of 94,000 gpd. Therefore, it is es timated 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 repo rt total quantity discha rged rather than flow rates to provide a more adequate future analysis of bilge water quantities discharged.ODCE for Arctic NPDES General Permit 1/24/06
2-18 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
3-1 

## 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 dril ling fluids. Therefore, this analysis only discusses the transpor t, persistence and fate of water-based drilling fluids, specialty additives, and cuttings discharg ed to the marine environment.

Drilling fluids (muds) contain quantities of coarse material, fine material, dissolved solids, and free liquids. This mixture rapidl y separates in the receiving wate r into upper and lower plumes, probably from shear forces and local turbulent fl ow 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 dri lling muds and cuttings wi ll initially reach the
seafloor within a few hundred meters from the dr illing platform. The th ickness of the cuttings pile would decrease with distan ce from the platform. Finer mate rials, (e.g., barite and clays) associated with the cuttings, may extend further ou t from the platform. The subsequent fate of the upper and lower plumes will depend primar ily 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 stab ilizing 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, se ttling, and diffusion. Factors influencing the physical transport and persistence of discharged drilling muds and cuttings include climate and meteorology, oceanography, characteristics of the di scharge (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 di sposal methods are discu ssed in this section: open water disposal, on-ice dispos al, and below-ice discharge. Shunting, the extension of the discharge outlet well below the sea surface, of drill ing mud discharges is also discussed in this
section.

Field studies and models of the behavior of drillin g fluids and cuttings discharged to the marine environment have focused on several aspects of their fate. Among thes e aspects are: the transport of discharged materials in the wa ter column, both for particulate and soluble components; deposition on the seaflo or; and considerations of benthi c short- and long-term fate. Field studies are discussed in Section 3.1.5 and pr edictive models are discussed in Section 3.1.6.ODCE for Arctic NPDES General Permit 1/24/06
3-2 In the drilling process, rock fr agments (cuttings) are brought to th e surface in the drilling fluid (muds). These cuttings pose a problem both in th e large volume produced and the muds that coat the cuttings as they are extracted. Oil-base d fluids have the added stigma of having oil frequently coating the cuttings.

Drilling mud disposal generally becomes an issue at the end of the drillin g process. However, sometimes drilling mud is disposed of during th e 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 dispos al 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 ma king of drilling mud, which passes 40 CFR 435 requirements [less than or equa l 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 dissol ved and suspended contaminants including mercury, cadmium, arsenic and hydrocarbons (typi cally 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 cr eate a large volume of waste and for water-based fluids the rock cuttings may be discharged to surface waters offshore. Oil-based mud will alsocontain 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 re duces waste volume from drilling operations.

3.1.1. Climate and Meteorology

The Area of Coverage is located in the Arct ic and subarctic climate zones. Important meteorological conditions include air temperatur e, precipitation (rain and snowfall), and wind speed and direction. Air temp erature controls the ice form ation and break-up, precipitation determines the quantity and concentration of pollu tants discharged in deck drainage discharges, and wind speed and direction control coastal o ceanographic conditions (ice distribution, current speed and direction, vertical and ho rizontal 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 Septem ber 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 wint er temperature ranges from -33 to -6° C (-27 to 21° F).ODCE for Arctic NPDES General Permit 1/24/06
3-3 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 mo nths (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 ther e is still open water on the Beaufo rt 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 precipitati on 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 rainfa ll is recorded in the months of July, August and September.

3.1.1.3. Winds

The Arctic region is a pa rticularly harsh environment, especi ally 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 sout h, 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 co lumn 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 part ly 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 Ra nge is approached. St ations to the east of Prudhoe Bay have more frequent we sterly 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 pred ominantly 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 pe rcent 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 southwes t to a winter flow, which averages 10 to 15 kn
from the east and southeast.ODCE for Arctic NPDES General Permit 1/24/06
3-4 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 shif t. 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, wher eas 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 in sulates the sea ice from the relatively warm Atlantic waters, appears to have retreated from th e Eurasian Basin in recent years. This may be a result of atmospheric circulation anomalies cau sing a diversion of Russian river runoff and has important consequences for ice/ocean heat exchange and ice grow th rates. [MMS, 2003]

3.1.2. Oceanography

Oceanographic considerations include tides, wind, freshwater overflow, ice movement, stratification, and current regime. The ocea nographic and meteorologic conditions affecting dilution and dispersion for the Beaufort and Chuk chi seas, and Hope and Norton Basins will be briefly summarized below and will include releva nt 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 c ontinental 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 coastlin es 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 wa ves hitting the island at an angle can
move the sand from one end of the island to another. For example, the offshore currentsODCE for Arctic NPDES General Permit 1/24/06
3-5 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 eff ects 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 submerge d plain that is an underw ater 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 pl unge downward to the great depths of the ocean basin proper. Deep submarine canyons are some times found cutting across the shelf and slope, often extending from the mouths of terrestrial rivers. Many c ontinental slopes end in gently sloping, smooth-surfaced features ca lled continental rises. The c ontinental 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 grea t variation in shelf features, non-glaciated shelves are usually exceptionally flat, w ith seaward slopes averaging on the order of 205 meters per kilometer (m/km) [10 f eet 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 contin ental slope in the Beaufort Sea has water depths varying from 60 (197 ft) to 1,500 m (4,921 ft). The major submar ine 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 ca rrying 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 th e major oceans, and they extend from bordering continental rises to mid-oceanic ridges. Abyssal pl ains 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 mo re steeply sloped than those of the Beaufort Sea and are dominated by barrier island protected bays an d points and capes that extend from the coast and occasionally form prot ected bays. Within the Chukchi Sea Area of Coverage, the continental shelf is broad, has low re lief, and is gently incline to the north (MMS 1991). The entire area of coverage is located on th e continental shelf in water depths from 6 toODCE for Arctic NPDES General Permit 1/24/06
3-6 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 divide d 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 th e 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 divide d into two main areas: ne arshore (water depths less than 40 m; and offshore (water depths grea ter 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 Beaufo rt 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 circ ulation: open water and ice covered. The open water circulation depends mostly on the direct ion (rather than speed) of the wind; the two
dominant wind directions are northeast and southw est (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 su rface currents to flow west and westerly winds
cause surface currents to flow east. The mean surface current di rection year-round is to the west and parallels the bathymetry. Th e tidal action coupled with the easterly nearshore circulation results in the gradual removal of warm, brackis h 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, br ackish water along the coast. Other controls on
nearshore circulation include rive r discharge, ice melt, bathymetr y, and the configuration of the
coastline.

During ice covered periods, the la ndfast ice in the nearshore areas protects the water from the effects of the winds. Therefore, the circulat ion pattern is influenced by storms and brine drainage (MMS, 2003).

The Chukchi Sea is fed by Pacific waters and Arc tic waters. Pacific wa ters enter the Chukchi Sea through the Bering Strait in th e south. Arctic waters ente r 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 th e input to the Arctic
Ocean from the Pacific.ODCE for Arctic NPDES General Permit 1/24/06
3-7 In Norton Sound, the circulation is weakly cycl onic [~ 1.0 centimeters per second (cm/s)]. During open water season, the fresh water runoff cau ses water-column stratific ation that dictates the circulation in Norton Sound. As a result, the upper layer circulati on is largely uncoupled from that of the lower layer.

3.1.2.3. Currents

The direction of the current determines the pr edominant location of potential impacts, while current velocity influences the extent of area affected. Veloci ty and boundary conditions also affect mixing because turbulence increases with current speed and proximity to the seafloor. Current velocity and turbulence ca n 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 wa ters on the continental slope. It moves to the east with frequent reversals to the west. The Beau fort 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 st rongly influenced by the Alaskan coastal current. This easterly flowing count ercurrent 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 in fluenced by the bathymetry and wind. Current speeds of 20 to 30 cm/s (0.66 to 1.0 cm/s) are char acteristic 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 Kot zebue Sound on the Chukchi Sea current may be significant. Input of the wate r 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 Lisbur ne, 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 fl ows southeasterly parallel to the coastline. The
ACC flow is variable and direc tional reversals can pe rsist for several week s due to changes in wind direction. During northeasterly flow, cloc kwise eddies can separate the nearshore circulation from the ACC between Cape Lisburne and Icy Cape (MMS, 1990).ODCE for Arctic NPDES General Permit 1/24/06
3-8 During open-water periods, the onshore and offshor e of nearshore water is driven by the wind. Northeasterly winds promote upwelli ng that brings cooler bottom wa ter 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 o ffshore, 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 coherenc e 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 lo w amplitude (range is 6-10 cm) and influenced by the wind (MMS, 2003). Offshore tides are near ly nonexistent. Tidal currents within Norton Sound are predominantly diurnal, except near the entrance where semi-d iurnal components are also important. The magnitude of the tidal excurs ion 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 i ndicate ranges of 1.6 to 6.8 ft w ithin the Norton Sound Area (MMS, 1982).

3.1.2.5. Stratification, Salinity, and Temperature

Nearshore waters are influenced by fresh water fro m 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 th e 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) isoba th. Alaska Coastal Water temperatures range between 5-10° C and has salinities that are ge nerally less than 31.5 part s per thousand (Lewbel and Gallaway in MMS, 2003). Offshore waters are colder and more sa line than the Alaska Coastal Water. Water temperatures are near 0°C and have salinities of 32.2-33 parts per thousand (ppt) (Lewbel a nd Gallaway in MMS, 2003).

3.1.2.6. Sea Ice

Sea ice is frozen seawater that floats on the o cean surface, and forms and melts with the polar seasons. In the Arctic, some sea ice persists ye ar after year, whereas almost all Southern Ocean
or Antarctic sea ice is "seasona l ice," meaning it melts away and reforms annually. Sea ice in the Arctic appears to play a crucial role in regula ting climate because it regul ates exchanges of heat,ODCE for Arctic NPDES General Permit 1/24/06
3-9 moisture and salinity in the polar oceans. It insulates the rela tively warm ocean water from the cold polar atmosphere except where cracks, or lead s, in the ice allow exchange of heat and water vapor from ocean to atmosphere in winter.

Ice thickness, its spatial extent, and the fracti on 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 (km 2 ) 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 variabi lity. 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 belo w the horizon for continuous periods in winter require microwave sensors to map ice cover.

There are four major zones of sea ice in the Arc tic: 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 floe s of multiyear pack ice. Much
of the fast ice melts within the 10-m isobath during the summ er, 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 betw een 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 th at are formed between the landfast ice and the pack ice when offshore winds carry loose i ce away from consolidated ice. [MMS, 2003]

3.1.2.6.3. Pack-Ice Zone

Pack ice is located seaward of the stamukhi i ce 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 Ba rrow, there is often a band of open water seaward of the landfast-ice zone during winter and spring. The Chukchi open-water systemODCE for Arctic NPDES General Permit 1/24/06
3-10 appears to be the result of the general westward motion seen in the Beau fort 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 a nd large necks of land (MMS, 2003).

Ice islands are icebergs that ha ve broken off from an ice shel f with a thickness of 30–50 m and from a few thousand square meters to 500 km 2 in area. Ice islands often have an undulated surface, which gives them a ribbed appearan ce from the air (Armstrong et al., 1973).

Movement of the floating ice is controll ed by atmospheric systems and oceanographic circulation. During the winter, m ovement is small and occurs with strong winds that last for several days. The long-term direction of ice move ment 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 predom inantly 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 northe rn 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 dr amatic reduction in regional ice cover. In September 2002, sea ice in the Arctic reached a record mini mum (Serreze et al., 2003), 4 percent lower than any previous Septembe r since 1978, and 14 percent lower than the 1978- 2000 mean. In the past, a low ice year w ould be followed by a rebound to near-normal conditions, but 2002 has been followed by two mo re 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 co mplicated. 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 sh ifted 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 thatODCE for Arctic NPDES General Permit 1/24/06
3-11 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 importan t transport mechanism, particularly in the fall when such storms are associated with fresh ice, which enhances the erosion and often entraps sediments in the formi ng ice. Subsequent ice movement and melting in the spring can deposit sediment large di stances from the point of entrapment.

Sediment transport and distributi on in the Chukchi Sea is controll ed 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 tr ansported 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 fres h ice, which enhances erosion and often entraps sediments in new ice. In the spring, the brea kup and melting of this sediment-laden ice can result in sediment being transported larg e distances from the point of entrapment.

3.1.3. Upper Plume Transport Processes

The materials contained in the upper plume ma y be subjected to immediate wake-induced turbulence, and then are influenced by oceanic tu rbulent dispersion processes. These materials are transported at the speed and direction of prev ailing currents. Sinking rates of solids in the upper plume will largely depend on four factors: di scharged material properties, receiving water characteristics, currents and turbulen ce, and flocculation and agglomeration.

Physical properties of the disc harged materials affect mixing a nd sedimentation. For suspended clay particulates, particle size and both phys ical and biological flo cculation will determine settling rate. While oil exhibits little tendency to sink, it has disp layed 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 ch aracteristics influencing plume behavior is density structure and stratification. Density strati fication can contribute to the dissi pation of dynamic forces in the dynamic collapse phase of plume behavior, and re presents the point at which passive diffusion and settling of the individual par ticles become the predominant dispersive mechanisms. Density stratification may concentrate ce rtain components along the pycnoclin e. If flocculation producesODCE for Arctic NPDES General Permit 1/24/06
3-12 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 uppe r 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 be havior by increasing sedimentation rates as larger particles are formed. Flocculation is enha nced 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 offecal 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 c oncentration of discharged fluid

. suspended solids concentration in samples

Most studies of upper plume behavior have m easured particulate components and paid less attention to the liquid and dissolv ed 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 so lids in the upper plume may undergo a higher dispersion rate than dissolved components.

Because drilling fluids contain bo th particulate and soluble compone nts, 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 dril ling 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 (fluorescei n) 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 distan ces to specified levels of dispersion). These correlations may be confounded by dye-clay interac tions, rendering this comparison more similar than would a true “soluble” component.ODCE for Arctic NPDES General Permit 1/24/06
3-13 3.1.4. Lower Plume Transport Processes

The physical transport processes affecting th e 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 bott om 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 settli ng to the bottom from the lower plume depends on collision and cohesion of clay particles, which in turn depe nds 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 partic les. Presently, there are no water column sampling data from the lower plume. Its dynamics must be infe rred 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 ha ve been attempted. Data on the short-term fate of drilling discharges associat ed with lower plume appears largely to address the initial deposition of the material on the seafloor. Howeve r, the lack of informa tion on the behavior of the lower plume is not critical due to the short duration of drilling activities.

Biological processes have been shown to incr ease 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 ex crete 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 flui d accumulation on the bottom to be inversely related to the energy dynamics of the receiving water. Verti cal mixing also appears to be directly related to energy dynamics. Low en ergy environments, however, are not subject to currents removing deposited material from the bo ttom or mixing it into sediments. Vertical incorporation of plume components into sediment s is caused by physical resuspension processes and by biological reworking of se diments. 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 th e true field case because no initial downwardODCE for Arctic NPDES General Permit 1/24/06
3-14 motion was assumed, which provides for a longe r settling time and greater plume dispersion. The result was an elliptical patt ern, 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. Th is is the greatest ar eal extent of bottom sedimentation for continuous discharges under the assumed conditions. Discontinuous discharges will be transported by currents at the tim e of release and will form a starburst pattern
over time.

Currie and Isaacs (2004) examined changes to be nthic infauna caused by e xploratory 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. Th e 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 persiste d at the well-head for more than 11 months following exploratory drilling. Changes in th e abundance of species aggregated by phylum varied, but significant declines in the most abundant phyl a (crustaceans and polychaetes) of 45 to 73 percent were observed at all sites within a 1 00 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 material s discharged into the marine environment from exploratory drilling opera tions have been previously eval uated for several northern Alaska offshore areas of coverage. The general conclu sions reached in these studies regarding the transport, dispersion, and pe rsistence of drilling discha rges is summarized below:

• The drilling mud discharge separates into an upper and lower plume. Physical descriptions of effluent dyna mics and particle transport di ffer substantially for the two plumes.

• Drill cuttings (parent material from the drill hole) are generally coarse materials that are deposited rapidly following discharge and set tle within the 100-m radius mixing zone.

• Discharged drilling materials typically settle in the immediate vicin ity of the discharge area. However, deposition patterns are extrem ely variable and are strongly influenced by several factors, including the type an d 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 we re generally low to moderate, seldom exceeding a factor of 10. Th e spatial extent of this enrichment also
was limited. These considerati ons suggest that exploratory activities will not result in environmentally significant levels of trace me tal contamination. However, other factors, such as the intensity of exploratory activ ities, normal sediment loading, and proximity
either to commercial shell fi sheries or to subsistence populations, could alter this
conclusion.ODCE for Arctic NPDES General Permit 1/24/06
3-15 • 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 concentra tions of barium are persistent ly 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 afte r drilling, then this findi ng 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 indi cate that several metals are deposited, in a distance-dependent manner, around platform s, including cadmium, chromium, lead, mercury, nickel, vanadium, and zinc.

• At present, the area-wide large-scale distri bution of drilling discharges is difficult to predict. However, it can be surmised that dr illing discharges associ ated with short-term exploration operations will have little eff ect 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 enviro nmental distribution of metals from drilling fluids discharged into the Beaufort Sea, near the Mackenzie Ri ver 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 arti ficial island constructed
from local borrow material in the Beaufort S ea near the Mackenzie River delta. The average depth of the study area was approxi mately 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 di scharge. Subsurface concentrations of most metals, excluding chro mium, were substantially higher than surface sediment sample 45 m SW of this discharge loca tion. 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 poi nt 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, ju st north of the discharge.

Another study was conducted to monitor the environm ent fate associated with above ice disposal of drilling fluids and cuttings in the Beaufort Sea (Sohio Al aska Petroleum Company, 1980). Three wells were sampled, Sagavanirktok De lta 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 dis posal sites. For post-discharge tests of disposal sites versus reference sites, a few significan t differences were found. Median grain size decreased at Sag 8 and Challenge 1 (Site C) for the >0.25 mm (per centage coarser) fraction and at Sag 8 for theODCE for Arctic NPDES General Permit 1/24/06
3-16 >0.150 mm fraction. Increased medi an grain size occurred fo r 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 botto m 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 si gnificant 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 dr illing fluids disposal. Cadmium data were not considered to be explained by effluent discharg es 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 sedime nt characteristics, and because Site C did not melt in place.

However, elevations of cadmium and lead leve ls could be effluent-r elated. 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 dril ling fluid effluents occu rred at all disposal sites over time, to 0.8-1.1 mg/kg. Also, for cadmi um, chromium, lead, and zinc sediment levels were inversely related to distan ce 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 with in-site or far-field (315-585 m) stations. These enrichments were not statistically significa nt. 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 consis tent. 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 incr eased 2-fold versus 1.4- fold at Challenge 1.

A study has assessed the impacts of above-ice dr illing effluent dispos al 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 i ndicated that a rapid de crease in deposition rates occurred for most particle sizes. At the cen ter of the discharge hol e, deposition was 729 milligrams per square centimeters (mg/cm 2 ) for all grain size fract ions. At 1.5 m and 3.0 m, average deposition was 313 mg/cm 2 and 168 mg/cm 2 , respectively. It was estimated that the average deposition of all part icle sizes was about 200 mg/cm 2 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 measur ed at two below-ice di sposal sites (166 mg/cm 2ODCE for Arctic NPDES General Permit 1/24/06
3-17 versus 66-268 mg/cm 2 , respectively). Bottom sediment trace metal levels indicated the presence of drilling effluents three days after the disc harge, 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 di fferences 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 occu r as a result of drilling activities. While confounding factors occur in most of these studies (i.e., seasonal va riability and other natural and anthropogenic sources of these metals) a distance-d ependent decrease in metal levels frequently is observed. However, although drilling activi ties are implicated as a source of metal enrichment, discharged drilling fluids and cutt ings probably are not th e only drilling-related

source.

Barium and chromium are the only two metals that appear to be el evated around rigs or platforms and are clearly associat ed with drilling fluids. A st udy 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 opera tions is notably under-represented in the studies that have been reviewed. The degree of simila rity between Canadian a nd domestic operations has not been evaluated. However, the findings of the Netserk study and lack of information on domestic operations indicate that the relationshi p between drilling fluid di scharges 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, va nadium, and zinc. Cadmium, lead, and zinc may be associated with drilling fl uids as contaminants that occur from the use of pipe dope or pipe thread compounds. Mercury, nickel, and zi nc may originate from sacrificial anodes. Cadmium, lead, and vanadium may also originat e from the release of fossil fuel in drilling operations. This release can resu lt from burning, incidental discharg es or spills from the rig or supply boat traffic, or use as a lubricant in dr illing 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: enrich ment was generally distributed but undetectable beyond 300-500 m or enrichment was directionall y-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. Ho wever, other factors, such as the intensity of exploratory activities, normal sediment loading, and proximity either to commercial shell fisheries or to subsistence populat ions, could alter this conclusion.ODCE for Arctic NPDES General Permit 1/24/06
3-18 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 (a ctual) toxicity may be due to phys ical effects, such as particle size coagulations, abrasions, et c. These are, however, a fo rm of toxicity, producing and contributing, in part or in combination with chem ical toxicity, to the end points (death) in acute toxicity tests.

Oxygen demand appears strongly correlated with toxi city in laboratory toxi city tests. Spearman
Rank correlations of 96-hour LC 50 data and biochemical oxygen demand (BOD)/ultimate oxygen demand (UOD) data showed a remarkably strong correlation, especially with 5-day biochemical oxygen demand (BOD 5 ) 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 nongene ric 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 especi ally 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 orga nisms have been exposed to drilling mud in laboratory or field experiments. Most of these studies have addr essed short-term acute effects in a relative or “screening” sense, with little e ffort directed at separating chem ical from physical causes. [In aquatic toxicity tests, a response measuring 50 percent lethality observe d in 96 hours or less is typically considered acute (LC 50 )]. 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 peri od of time, often one-ten th of the life span of an organism or more (USEPA, 1991). Chronic te sts assess the effect on surviv ability, growth, maturation or reproduction and the results are typically reporte d as median effective concentrations [EC 5O s (concentrations at which a designated effect is di splayed by 50 percent of the test organisms)]. Because drilling discharges are episodic and ty pically only a few hours in duration, organisms
that live in the water column are not likely to have long-term expos ures to drilling muds; risks to these organisms are best assessed using acute toxi city data. Benthic organisms, particularly sessile species, are likely to be exposed for longe r time periods; risks to these organisms are best assessed with chronic toxicity data.

Drilling mud toxicity tests have been perfor med 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 reflecte d in the results and interpretation of toxicity tests. Test results of sample splits of the same mud performed at two diffe rent laboratories have differed by an order of magnitude. In such cases , laboratory procedure or sample handling is a significant factor. Different batc hes of the same generic mud ha ve shown significantly different toxicities. In this case, diffe rent proportions of major consti tuents (as allowed by mud type definition) may be a factor. EPA has attempted to improve consistency in toxicity test results byODCE for Arctic NPDES General Permit 1/24/06
3-19 requiring standard procedures for sample handling a nd testing that has resulted in consistent test results. The current effluent guidelines require toxicity testing for th e 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 or ganisms are most commonly assessed by conducting acute laboratory toxicity tests. Unfortunately, in many cases, comp arison 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 particul ates, 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 LC 50 s ranging from 100 to 999 ppm, 6 percent exhibited LC 50 s ranging from 1,000 to 9,999 ppm, 46 percent exhibited LC 50 s ranging from 10,000 to 99,999 ppm, and 44 percent exhibited LC 50 s greater than 100,000 ppm (USE PA, 1985). Table 3-2 provides a summ ary of these toxicity tests. Two to three percent of the data were not usab le. A significant differen ce was noted between the toxicity of generic muds, which appear to have acut e, lethal toxicity characteristics similar to the distribution of the larger data set described above, and a seri es of 11 nongeneric muds provided to EPA by the Petroleum Equipmen t Supplies Association. These latter muds, as a group, appear to be substantially more toxic than would be antic ipated 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 suspe nded 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 sens itivity: copepods and other plankton, shrimp, lobsters, mysids and finfish, bivalves, cr abs, 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 appare ntly 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 rate s, 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 ha ve not been tested, but there is no reason to
believe their tolerances would fall outside variab ility 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. Carl s and Rice (1981) foundODCE for Arctic NPDES General Permit 1/24/06
3-20 several drilling muds to have lo w toxicity to the larvae of si x Alaskan species of shrimp and crab. The 96-hour LC5Os for the suspended pa rticulates 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 severa l 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 hi gh-density lignosulfonate drilling fluid from lower Cook Inlet, Alaska. Pink salmon fry were the most sensitive with a 96-hour LC 50 of 3,000 ppm for SSP. The lowest crustacean concentration was ten time higher.

Seven arctic polymer drilling fluids were used fo r toxicity testing of salmon (Houghton et al. in USEPA, 1985). Five of the se ven fluids displayed a 96-hour LC 50 of less than 40,000 ppm for the SSP fraction; the most t oxic fluid had a 96-hour LC 50 of 15,000 ppm, and the least toxic fluid
a 96-hour LC 50 of 190,000 ppm. Clam worms (polychaetes ), soft-shelled clams, purple shore crabs, and sand fleas had approximately the same sensitivity to the flui ds as did the salmon.
These invertebrate 96-hour LC 50 ’s ranged from 10,000 to more than 560,000 ppm.

Unlike the water-based drilling fluids (WBFs), th e synthetic-based drilling fluids (SBFs) are water insoluble and do not disperse in the wate r 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 te st, 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 indica ted that SPP toxicity results are highly variable when applied to SBFs (USEPA, 2000a). Table 3-3 summarizes toxicity test results conducted with water-colu mn and benthic organisms for several differentSBFs. 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-inter nal olefins-linear alpha olefins-polyalphaolefinsparaffins (USEPA, 2000a).

The current NPDES permit has incorporated a standard acute toxicity test fo r drilling fluids prior to discharge. The acute toxici ty test must result in an LC 50 value higher than 30,000 ppm for discharge of the cuttings to be permitted. The permit require s 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 i ndicate 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.ODCE for Arctic NPDES General Permit 1/24/06
3-21 3.1.6.2.2. Chronic Effects

Few studies have evaluated impacts on Alaskan species following chroni c exposure to drilling muds; the species that have been tested are all invertebrates. Th e 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 toxi city 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 rout inely are very small. Most importantly, obse rvations 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 developmen t of benthic communities suggest that drilling
mud and barite can affect recruitment and alte r benthic communities or depress abundances. These data are corroborated by results from ar tificial substrate experiments conducted in the Beaufort Sea; these showed significantly different colonization rates at dr illing fluid test plots and control plots, especia lly for amphipods and copepods.

The lowest reported concentration of drilling mud producing a significa nt sublethal chronic effect was 50 mg/L for 30 days of continuous exposure with bay mussels, and there was no attempt to separate chemical fr om 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). Exposur e to mixtures as low as 10 percent cuttings/90 percent sand were found to affect the survival of the be nthic organisms, with 100 percent mortality oc curring within 23 days in some test cases.

Other altered behavioral pattern s in organisms have been noted after chronic exposures to drilling mud. USEPA (1985) discusses a study wh ere 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 swim ming ability of half of the cr ab larvae ranged from 77,600 to 85,600 ppm bentonite, and was 71,400 pp m for barite. EC50’s for shrimp larvae ranged from 13,800 to 34,600 ppm bentonite, a nd 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 a dded diesel oil to drilling fluid sy stems 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 LC 50 ) of drilling muds has been attributed to its presence. Studies have found high correlations of toxicity w ith 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). Th e available data indicat e that this may beODCE for Arctic NPDES General Permit 1/24/06
3-22 partially due to various types of sequestrations within the drilling fluid matrix as well as the variable presence of toxic const ituents in drilling fluids other than diesel or mineral oil.

Because of the toxicity of diesel oil, USEPA ha s prohibited its discharge in muds and cuttings. Instead, USEPA allows the use of mineral oils to free stuck pipes and th e 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 resi dual mineral oil concentra tion in the discharged mud should not exceed 2 percent (v/v) and must co mply 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 lubric ity agents and spotting fluids as of 1986. With
the advent of Best Practicable Control Technolo gy Currently Available (BPT) effluent limitation guidelines, however, current diesel oil usage fo r these purposes is assumed to be zero (USEPA, 1993a).

Mineral oils differ from diesel oils in that they contain a lo wer concentration of aromatic hydrocarbons (15-20 percent vs. 20-61 percent for diesel oil) (USEPA, 1993a). In addition, saturated aliphatics (paraffinics) generally represen t a larger percentage of mineral oils compared to diesel oil. Aromatic hydr ocarbons 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 organi c pollutants (Table 2-3) to dr illing 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 per cent vs. 20-61 percent for diesel). Due to the
fact that the total amount of mineral oil released in the drill ing cuttings is, effects in aquatic organisms due to exposure to PAH residue s is not expected to be significant.

3.1.6.3. Open-Water Discharges

Only one Arctic discharge study has consider ed discharges during the open water period. Northern Technical Services (NORTEC, 1983) c onducted a drilling effluent disposal study at
Tern Island located in the Beaufort Sea. Case 1 conditions included a m ud discharge rate of 13.3 cubic meters per hour (m 3 /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) aboveODCE for Arctic NPDES General Permit 1/24/06
3-23 the seafloor. Case 2 conditions incl uded a mud discha rge rate of 5.4 m 3 /h (34 bbl/h), predilution of 75:1 with seawater, and an av erage current of 11 cm/s (0.36 ft/s ). The minimum dilution (due to ambient waters only) measured for test pl ot 1 was 167:1 at 100 m (330 ft) and 320:1 at 160 m (530 ft) from the discharge for test plot 2. Du ring 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 exam ined in the Beaufort Sea. Results suggested that ne arfield dilution (100- to 1,000-fold ) was 1-2 orders of magnitude less than in open water situations. However, at dilution ratios of 10 4 to 10 6 , 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) c onducted two shallow water under-ice effluent disposal studies in 8.4 m (27.6 ft) and 5.5 m (18.0 ft) off Reindeer Is land 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 dist ribution 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) thic k extended less than 61 m (200 ft) beyond the toe
of the island.

NORTEC (1985) identified the distribution of dr illing muds discharged under the ice from Mukluk Island, an artificial grav el 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 indi cated 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 else where in the Beaufort Sea.

3.1.6.5. Above-Ice Discharges

Field studies (Sohio Alaska Petroleum Company, 1980, 1981) ha ve found that the maximum mud concentration entering the marine environmen t 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 di scharge to open waters, as the solids are released slowly during ice me lting and breakup allowing greater dispersion.ODCE for Arctic NPDES General Permit 1/24/06
3-24 3.1.7. Predictive Modeling of Drilling Mud Tr ansport, 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 compan ies and federal and state agen cies concerned with offshore drilling discharge regulation in 1983. The OOC model considers th e 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 behavi or: 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 pred icts concentrations of solids and soluble components in the water column and the in itial deposition of solids on the seafloor.

The OOC model results do not include cuttings becau se 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 tota l discharge of drilling muds for these operations. Thus, the nearfield esti mates (within 100 m of th e point of discharge) of bottom accumulations of drilling mud shoul d be considered underestimates due to the exclusion of cuttings disc harge from the OOC model.

Comparison of mode1 results with field observati ons indicates that the model is capable of predicting many important aspects of drilling m ud discharge plume behavior. For example, a field verification study wa s conducted offshore of Huntington B each, California, in waters with an average depth of approximately 18 m using a modified version of th e OOC model (O’Reilly et al., 1989). The model predicte d water column solids concentrati ons were within the range of concentrations measured at 75 percent of the sa mpling locations. In the lower water layer where the majority of the solids formed the lower plum e, the model predicted the solids concentrations at 86 percent of the lower wate r layer sampling locations. However, comparison of the model predictions of bottom solids accumulation with fi eld sediment trap data was less satisfactory, possibly due to errors associated with the field measurement technique that was used.

The OOC model makes several simp lifying assumptions that may va ry from actual conditions at any given site (e.g., a single discharge of lim ited duration and unidirectional currents). Therefore, the model predictions discussed belo w provide a generalized picture of expected dilution and deposition; but the model is not exp ected to predict exact co nditions at any one well location. The model version employed for th is 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 scen arios 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 we re not likely to occu r (see Section 2.2.1). Discharge scenarios were determined by examin ing relevant information sources describing exploratory oil and gas drilling pr actices. Maximum allowable discharges are those specified in the NPDES general permit for the Arctic, whic h are based on previous OOC model runs for earlier ODCEs in this area. Model parameters held constant for all test cases are given in TableODCE for Arctic NPDES General Permit 1/24/06
3-25 3-4. The NPDES permit states that the total drill ing muds and drill cuttin gs 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 require ments, the NPDES general permit also specifies the following seasonal requirements:

• During open-water conditions, discharge is pr ohibited at depths greater than 1 meter below the surface of the receiving water betw een 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, disc harge is prohibited w ithin 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 av oid 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 depositi on of drilling muds in
offshore waters of the Beaufort and Chukchi s eas, 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 to tal amount of drilling m ud discharged to these waters following the completion of the averag e 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 discharg ed mud is primarily a function of the discharge rate, and not of the total mass discharged, varia tion in the total amount of dril ling 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 aff ect 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 th at occur within th e areas (Section 5.3).ODCE for Arctic NPDES General Permit 1/24/06
3-26 OOC model test cases that refl ect the permit stipulations disc ussed above were run for openwater discharges, shunting, and be low-ice discharges; results of the model runs are discussed below. Above-ice discharg es are also discussed.

3.1.7.1. Open-Water Discharges

Open-water discharges were modeled for three depth and discharge comb inations. OOC model predictions for the open-water discharge test case s 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 av erage 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 Co verage 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, re spectively. [The OOC model test cases assume discharge durations of one hour.]

Although the estimates of minimum solid- and disso lved-fraction dilutions will not be affected by the differences between modeled and actual di scharge amounts, solids deposition will be underestimated. An estimate of the solids depos ition resulting from the discharge of the quantity of mud necessary to drill an average, expl oratory well was obtained by multiplying the OOC model predictions by a factor (e .g., 2.613) that represents the ra tio 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 quanti ties of mud and is reasonable pr ovided 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 occu r 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 (T able 3-5). There has been only one shallow water study (Northern T echnical Services, 1983) of drilling effluentODCE for Arctic NPDES General Permit 1/24/06
3-27 disposal within the Beaufort Sea Area of Cove rage. The measured dilution factors and solids deposition patterns in that study support the results pr edicted by the OOC model.

3.1.7.1.2. 20-meter Water Depth

Model results for maximum allowable discharge rate s at a depth of 20 m (66 ft) reveal that the minimum solids dilution at 100 m (328 ft) wa s 1,326:1 and the minimum dissolved-component dilution at 100 m (328 ft) was 747:1. Approximate ly 84.4 percent of the di scharged 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 solid s 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 su rface may physically impact benthic communities within the area of coverage, and the potential im pact depends on the char acter 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, th e 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 Chukc hi 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 fo r each water depth and total mud discharge was calculated using the appropriate conversion factor as outlined above. All open-water cases represent a modeled unidi rectional current speed of 10 cm/s (0.33 ft/s).

5-meter Water Depth

. The model-predicted mud deposition de pth 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 percen t of the average) or less. Mud deposits beyond the mixing zone are predic ted 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 depositio n depth at the edge of the mixing zone for discharge to waters 20-m deep range d 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 forODCE for Arctic NPDES General Permit 1/24/06
3-28 discharges of 59,874 kg (132,000 lb) (i.e., 10 percen t 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 w ithin the mixing zone (Table 3-5).

40-meter Water Depth

. The model-predicted mud depositio n 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] o ccurs 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 wh en 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 Tabl e 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 disc harges [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 th e edge of the mixing zone. A maximum mud depth of 487.2 cm (191.8 in) occurre d less than 10 m (33 ft) from the discharge. The estimated mud deposition depth at the edge of the mi xing zone was 0.02 cm (0.008 in); more than 99 percent of the discharged so lids 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 di scharge 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 z one, with a mud deposition depth at the edge of the mixing zone of 0.14 cm (0.06 in) (Table 3-7).ODCE for Arctic NPDES General Permit 1/24/06
3-29 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 disso lved 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 su rface may physically impact benthic communities within the area of coverage, and the potential im pact depends on the char acter 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, th e 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 de posited mud for each water depth and total mud discharge was calculated using th e appropriate conversion factor as outlined above. All belowice cases represent a modeled unidirectiona l current speed of 2 cm/s (0.066 ft/s).

5-meter Water Depth . The model-predicted mud deposition de pth 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 depositio n depth at the edge of the mixing zone for discharge to waters 20-m deep ra nged 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 pr edicted 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 w ithin the mixing zone (Table 3-7).

40-meter Water Depth . The model-predicted mud depositio n depth at the edge of the mixing zone for discharge to waters 40-m deep range d 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] o ccurs within the mixing zone (Table 3-7).ODCE for Arctic NPDES General Permit 1/24/06
3-30 3.1.7.3. Above-Ice Disposal

The discharge of drilling muds and cuttings above ice is usua lly 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 di spersion of the effluent occur at ice breakup. No modeling results are presen ted due to the lack of an adequate model for above-ice drilling mud disposal. Modeling of the transport an d 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 redu ces the effective depth of the discharge, and therefore, reduces both the disso lved- and solids-fraction diluti on. 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 di lutions obtained when discharges are shunted. The fr equency of shunting during explor atory oil and gas drilling is unknown, as are the discharge depths that occur du ring 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 di scharges and results obtained in other OCS areas support the following conclusions for drilling mud di scharges in the area of coverage:

• Drilling muds tend to be diluted rapidly followi ng 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 a nd dispersion potential for discharges.

• The deposition and dilution of drilling muds for above-ice disposal has not been modeled; however, diluti on of muds is thought to be simila r or greater than that occurring during discharge to open-water disposal.

• Based on OOC model results, deposition of dril ling 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-iceODCE for Arctic NPDES General Permit 1/24/06
3-31 discharges, muds deposited in excess of 1-cm (0.4-in) in de pth outside the mixing zone may occur during discharges to water depths of 40 m.

• Based on estimates of mud deposit depths fo r open-water discharg e of various total drilling mud discharges it was determined th at 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 fo r below-ice discharges of various total drilling mud discharges it was determined th at 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 wate rs 40-m deep, mud deposits less than 1-cm deep beyond the mixing zone are not predicte d by the model unless the total drilling mud discharged is reduced by 50 percent.

• Shunting of drilling muds should be avoide d 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 colum n, redox/ionic changes, and adsorption of dissolved pollutants on solids. Chemical transport of drilling fluids is poorly described. Much must be gleaned from general prin ciples and studies of othe r, related materials. Several broad findings are suggested, but the da ta for a quantitative assessment of their importance are lacking. Chemical transport wi ll most likely arise fr om oxidation/reduction reactions that occur in sediments. Changes in redox potentials will effect the speciation and physical distribution (i.e., sorption-desorp tion reactions) of drilling mud constituents.

3.2.1. Inorganics

Most research on chemical transport processes a ffecting offshore oil and gas discharges focuses on trace metal and hydrocarbon components. The tr ace metals of interest in drilling fluids include barium, chromium, lead, and zinc. The source of barium in drilling fl uids is barite; barite may be contaminated with several metals of inte rest, 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 solubil ities for trace metals associated with powdered barite generally result in concen trations below background levels. Exceptions were lead and zinc sulfides, which may be released at levels suffici ent to raise concentrations in excess of ambient seawater levels. MacDonald (1982) found that less than five per cent of metals in the sulfide phase are released to seawater.ODCE for Arctic NPDES General Permit 1/24/06
3-32 Barite solubility in the ocean is controlled by the sulfate solubility equilibrium, which becomes
saturated at concentrations of 30 to 40 micr ograms 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 primar ily adsorbed on clay and silt particles, although some exists as a free complex with soluble orga nic 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 c onverted to the less toxic trivalent form by reducing condi tions downhole. The most probable environmental fate of trivalent chromium is precipitation as a hydroxi de 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 co mplexes 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 sett ling to the bottom, are subjected to different chemical conditions and processes than when su spended in the water column. These sorbed
metals can be in a form available to bacteria a nd other organisms if located at a clay lattice edge or at an adsorption site (Hought on et al., 1981). If the sediments become anoxic, conversion of metals to insoluble sulfides is the most probabl e reaction, and the metals are then removed from the water column. Environments that experi ence 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 pe rcent 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 C 10

.

After 10 minutes of mixing and a one-hour settling time for a one pe rcent mud/seawater mixture, 30 percent of the hydrocarbons were in the susp ended particulate phase, with five percent suspended and the remaining 25 percent in the aq ueous phase. The aqueous phase was relatively
enriched in C 10 alkanes. Neither C 1 -C 6 benzenes nor C 10 alkanes were present in the suspended phase. The suspended phase was enriched in alkylated naphthalenes a nd phenanthrenes, exceptODCE for Arctic NPDES General Permit 1/24/06
3-33 for C 3 phenanthrene. Suspended particulate phase (aqueous suspended) was enriched in C 0 -C 4 (not C 5 and C 6 ) benzenes, in C 0 -C 3 (not C 4 ) naphthalene and in C 0 -C 2 (not C 3 ) phenanthrene.

Proportionately, naphthalenes accounted for 84 pe rcent of aromatics a nd 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 w hole 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. Particulat e phase hydrocarbons increased form 5 to 18 percent of the total. After 4 hours, enrichment of the aqueous phase was limited to in C 2 -C 6 benzenes and C 0 napthalene, whereas the particulate phase was enriched in C 1 -C 4 naphthalenes and in C 0 -C 3 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 recove ry 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 C 2 -C 4 naphthalene and in C 0 -C 3 phenanthrenes. After 4 hours of mixing and on hour settling, 99.7 percent of hydr ocarbons were contained in the suspended particulate phase with 35 percent in the susp ended phase. The suspended phase was enriched in C 10 n-alkanes but not in any other hydrocarbon. The aqueous phase, however, was enriched in C 0 -C 3 naphthalenes
and C 0 phenanthrene. Overall recovery of aroma tic hydrocarbons in this experiment, however, was very low, thus hindering th e interpretation of these data.

3.3. BIOLOGICAL TRANSPORT PROCESSES

Biological processes include bioaccumulation in so ft or hard tissues, bi omagnification, ingestion and excretion in fecal pellets, and physical reworking to mix solids into the sediment (bioturbation). Biological trans port 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 re located within the water column;

• an insoluble form of an element or com pound is made available to the water column;

• an insoluble form of an element or compound is relocated.

The most effective way to monitor the biologi cal effects of drilling discharges is to take quantitative samples of the benthic infauna (a nimals that live on the sea floor). Sample variability is typically lower than that for pla nktonic 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 flui ds that accumulates on the bottom. The most common approach is to take re plicate quantitative samples and determine whether there have been changes in species richness, species co mposition, or abundance. With six replicateODCE for Arctic NPDES General Permit 1/24/06
3-34 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 fl uids is poorly described and the information must be gathered from general principles and studi es of other, related material s. Several broad findings are suggested, but the data for a quantitative a ssessment of their importance are lacking.
Bioaccumulation of a number of metals from ex posure to muds and mud components has been demonstrated in the laboratory and in the fiel d. Short-term laboratory experiments and field exposures indicate that tissue enri chment factors were generally le ss than an order of magnitude, with the exception of barium and chromium. Ho wever, 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 quali tatively 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 c oncentration in the or ganism. (USEPA, 1985)

The majority of research on metal accumulation from drilling fluids has focused on barite (barium) and ferrochrome lignosulfonate (chr omium). Table 3-12 provides a summary of laboratory data on metal accumulation discussed in the following paragraphs. Exposure to drilling fluids or dril ling 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 (P lacopecten magellanicus ) by exposing them for 4 weeks to a susp ension of synthetic mud equivalent to 0.074 g/L ferrochrome lignosulfate. They found th at chromium did not concentrate in the adductor muscle, but did concentrate in the ki dney from 1.7 to 4.4 mg/kg dry weight. Exposure to ferrochrome lignosulfonate al one (0.1 and 0.3 g/L) resulted in 6-fold elevations of kidney chromium concentrations. When sea scallops were exposed to synthe tic 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 c oncentrations decreased slowly; typically less than 10 percent after 24 hours.ODCE for Arctic NPDES General Permit 1/24/06
3-35 McCulloch et al., (1980) exposed the marsh clam ( Rangia cuneata ) to a layered solid phase of used ferrochrome lignosulfonate drilling fluid, c ontaining 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 e xhibited soft tissue increases in chromium
concentration of two- to three-fo ld in two days, and four-fold afte r 14 days. Lead concentrations in soft tissue increased two-fold after 10 days, wh ile no detectable increase in soft tissue zinc concentrations was noted (McCullock et al., 1980).

Tornberg et al., (1980) e xposed arctic amphipods ( Onisimus sp. and Boeckosimus sp.) to mixtures of used, freshwater XC-polymer drillin g 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 percen t mixture occurred for cadmium, chromium, and lead, and in the five percent mixture for zinc. Maximum uptake relative to cont rol organisms was five-fold for cadmium, and two-fold for chromium, lead, and zinc.

A field study of bioaccumulation in organism s around a drilling operation on the mid-Atlantic OCS analyzed tissue data from brittle stars, pol ychaetes, and mollusks. Based on discharge and sediment analyses, the only metals exhibiting elev ated tissue concentrations that were attributed to drilling discharges were barium and chro mium (EG&G, 1982). Barium concentrations increased significantly from pre-dr illing levels in polychaetes a nd brittle stars during the first post-drilling survey (two weeks after the comp letion of drilling activity); mollusks did not accumulate barium to an appreciable degree. Ba rium 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 increa se in tissue chromium le vels of all organisms over a year’s time indicates possible continue d bioaccumulation of chromium from the low
levels in the sediments.

Carr et al., (1982) exposed five marine speci es 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 chromi um 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 sy stem. They analyzed for barium in the carapace (hard tissue), hepatopancreas, and abdominal muscle (soft tissues) . They found that the shrimpODCE for Arctic NPDES General Permit 1/24/06
3-36 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 fl ow 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 bari um into soft tissues may provide a long-term opportunity for barium to enter the food chain.

In the exoskeleton, the shrimp were found to di scriminate for barium and against strontium relative to calcium. This changed the relative mi neral composition of cast exoskeletons of grass shrimp from calcium>strontium>barium for cont rol 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 inco rporation. Although these removal processes may not have toxic implicatio ns, they are pathways by which metals are
removed from the environment.

Chow and Snyder (1980) studied barium distributi on in hard tissues of marine invertebrates
collected from the southern Calif ornia coast, and found that barium concentrations in calcareous
exoskeletons were related to the type of organism and the mineralo gical structure of the skeleton. Calcite skeletons of gastropods ar e composed of a crystal lattice th at does not allow inclusion of the larger barium ion, whereas aragonite skeleton s of mussels form a la rger lattice structure which does allow for barium incorporation. Skeletons that incor porate other chemical compounds in carbonate form, such as those of th e barnacle and sea urch in, 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 st andard deviation of barium content in various organs of Mytilus exhibited the following trend: stomach >gills>muscles>gonads>shells. This trend supports the hypothesis that th e digestive tract is th e route of barium entry. The trend also indicates that marine organisms have some degr ee of regulation over the incorporation of barium
into their tissues.

Conklin et al. (1980) note that the mechanis ms of barium accumulation are poorly understood. There is some evidence that barium transpor t is mediated by a divalent-cation-activated adenosinetriphosphate (ATP) transport carrier as well as by micropinocytotic activity of the digestive epithelium. The latt er hypothesis is supported by ob servations that grass shrimp, juvenile lobsters, and meiobenthi c nematodes ingest particulate ba rite and accumulate it in their exoskeletons (Brannon & Rao, 1979; Chow & Snyder, 1980; Conklin et al., 1980).

Many crustaceans have long been know n 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 ectoderm al inner chitinous linin g and contents of theODCE for Arctic NPDES General Permit 1/24/06
3-37 statocysts (fluid, sensory hairs, and statoliths) are cast off dur ing 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 leve ls in exposed animals compared to control animal tissue levels) generally were low (1.6 to 3.4-fold), with the ex ception of barium (300- fold) and chromium (36-fold). Although functio nal changes resulting fr om 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 da ta are summarized in Table 3-13. Depuration studies suggest that a su bstantial 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 de puration periods. Possibly, le ngth of exposure and extent of depuration are inversely related. Transient increases were obs erved in chromium, lead, and strontium levels during the depuration period. Th e 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, thre e factors argued against th is 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 expos ure 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 o ccurs for several metals and species. However, complex saturation kinetics also occurs freque ntly. The long-term study with 106-day exposure did not report adequate data to characterize uptake kinetics. Sin ce metals are highly persistent, long-term accumulation potential must be assessed.

Second, the focus of these studies was often di ffuse. Bioaccumulation studies should identify which of two toxicologic problems is being addre ssed: (1) human health impacts (edible tissue analyses) or (2) marine organism impacts (target organ analyses). Functi onal studies must be
undertaken to link accumulation to adve rse physiological/biochemical responses.

Third, exposure levels were difficult to quantif y in a meaningful way for correlation to field exposure conditions. The assessment of the bioaccumu lation of drilling fluids related metals will be driven by the exposure of be nthic epifauna and infauna to dr illing 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 te sted solid phase material, accumulation was only measured in response to a deposit layer. Theref ore, no concentration-eff ect relationship can beODCE for Arctic NPDES General Permit 1/24/06
3-38 constructed that could estimate uptake from anything but a 100 pe rcent exposure situation. This design does not lend itself to a mean ingful quantitative assessment.

In order to simulate more rea listic 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 on e 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 bot h 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 per cent for barium, 25-60 percent for chromium). Thus, assessing exposure in these experiments is very difficult and ex trapolation to field conditions, in which concentrations increase dur ing drilling, is confounded by this experimental design, not simplified.

In summary, evaluation of the bioaccumulati on data for drilling fluids and components has
concluded:

• Several metals can be accumulated, including barium, cadmium, chromium, lead, strontium, and zinc. Mercury is abse nt in the laboratory uptake data.

• Any significant potential for adverse effects are opposed by the observations that enrichment factors are generally low (b arium and chromium excluded), depuration release levels are high, and no gross func tional alterations, resulting from metal accumulation following high exposures to drilling fluids or components, have been reported.

• There are several other observations that comp romise 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 e xposure concentration for fluid solids exposures; and the choice of tissues fo r 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 me tals, (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 absen ce of laboratory data on a significantly toxic metal (mercury), and (e) the inability to esti mate potential effects from environmentally realistic exposures.ODCE for Arctic NPDES General Permit 1/24/06
3-39 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 trophi c 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 asse ssment of biomagnification of the components of drilling fluid discharges. Studies have been examined, however, which assessed biomagnification of other inorganic and or ganic pollutants in various food chains.

In an experiment to evaluate food chain transf er, 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 (Ne ff et al., 1984). The mean barium level in contaminated worms was 22 μg/g, whereas the c ontrols 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 unc ontaminated sediment did not accumulate
barium in muscle tissue. Ther e was no significant uptake of ch romium in either flounder or lobster (USEPA, 1985).

Type of food had no effect on mean barium concentr ations 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 tran sfer. Throughout these experiments, the metal content of food was highly variable. Animal s may have gone through periods of uptake and depuration relative to this food and also the sedi ments 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 relationsh ip between food source and animal tissue concentrations.

Studies of DDT and PCB organochlorine co mpounds reveal that accumulation of these compounds in the tissues of fish, mammals and bird s from prey to predator occurs. Moreover, lipid concentrations show an in crease with trophic level which i ndicates that dietary uptake and subsequent biomagnification is taking place. Studies undertaken with fish provide clear evidence that organochlorine uptake occurs mo re rapidly than does el imination, leading to increasing pollutant burdens with time and sel ective 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 organochl orine biomagnification with mixed results. It was suggested that these studies failed because they assumed the primaryODCE for Arctic NPDES General Permit 1/24/06
3-40 organochlorine input was through the food chain, whereas recent studies indicate the water column may be the primary source, at least for zooplankton. Fowler specul ates that plankton and
small invertebrates accumulate substantial amount s of material from the surrounding water, and will reflect its composition more strongly than vert ebrates, which are generally larger and have less surface area for absorption a nd, 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 e nvironment. 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 pollu tant biomagnification show a decrease in trace metal and radionuclide burden with higher trop hic level. However, there are exceptions found in specific food chains. Dog whelks were found to have th ree 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. Howeve r, other experimental results have shown that whelks did not magnify zinc or iron in cont aminated 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 identif ied that address target organ sites, such as hepatopancreas or kidney tissues , which would be the functional an alogs 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 accumula te 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 organi sms (starfish) rapidly absorb plutonium from the water and eliminate it slowly. This furt her indicates the importa nce of knowing the uptake pathways prior to making conclu sions regarding biomagnification.

Studies assessing biomagnificati on 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 co lumn 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 di scharge of drilling muds and cuttings from exploratory drilling operations has little or no petroleum hydrocarbons, exposure to petroleum hydrocarbons would be minimal.ODCE for Arctic NPDES General Permit 1/24/06
3-41 3.3.3. Ingestion and Excretion

Organisms also remove material from suspensi on through ingestion of suspended particulate matter and excretion of this material in fecal pe llets. 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 suspen ded 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 m oves through the animal with the unassimilated food and passes out with the fecal pellets in a more concentrat ed state (Fowler as cited in USEPA, 1985). Zooplankton fecal pellets have also been found to contain high concentrations of petroleum oil, especially t hose of barnacle larvae and copepods . Hall et al. calculate that a population of calanoid copepods grazing on an oil slick could transport th ree tons of oil per square kilometer per day to the bottom.

3.3.4. Bioturbation

Another pathway of biological removal of pollu tants 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 dr illing mud to greater depths than they would
otherwise achieve. Bioturbati on can also expose previously bur ied 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 ha ve 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 domin ate resuspension and reworking processes, then biological mixing activities ma y not prove significant.ODCE for Arctic NPDES General Permit 1/24/06
3-42 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
4-1 

## 4.0 BIOLOGICAL RESOURCES

This section provides an overview of the biologi cal communities found within the Beaufort Sea, Chukchi Sea, Hope Basin, Norton Basin, and adj acent state waters. The general groups of aquatic organisms that inhabit the lease sale area s 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 resour ces is assessed in terms of seas onal distribution and abundance, growth and production, environmental factors, cr itical 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 meas ures are provided in Section 4.10. Assumptions for the effects analysis include:

• Exploratory oil and gas well drilling activitie s produce a wide range of waste that is discharged into receiving waters. The types of material discharg ed during exploratory operation mainly include drilling muds and cuttings, but also include sanitary and domestic wastes, desalination unit wastes, bo iler blowdown, test flui ds, deck drainage, blowout preventer fluids, uncontaminated balla st and bilge water, excess cement slurry, compounds used for equipment and drilling ma intenance activities, non-contact cooling water, and fire control system test water. Discussion of these disc harges 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 fair ly temporary and are widesp read throughout the Area of Coverage.ODCE for Arctic NPDES General Permit 1/24/06
4-2 • Exploratory oil and gas drilling generates a wide range of wa ste materials related to the drilling process, equipment maintenance, and personnel housing. These materials are commonly discharged directly from the rig in to the receiving water. Discharges of primary concern to this eval uation are drilling fluids, al so 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. Drilli ng muds can adversely affect marine life provided exposures are sufficiently long and concentrations sufficiently high. Effects can occur due to chemical toxicity, cl ogging of feeding or re spiratory 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 constituen ts of drilling muds are aromatic compounds and heavy metals. The NPDES permit incorpor ates a standard acute toxicity test using the mysid Mysidopsis bahia. Under these permits, discha rge of muds with a LC 50 of less than 30,000 ppm SPP (suspended particulate phase ) is prohibited. Dr illing mud toxicity data compiled by USEPA, Region-l0, from Alaskan exploratory and production wells
indicate that the muds used in all current a nd recent operations are acutely toxic only to a slight degree to Mysidopsis bahia. Only 7 of the 91 tests had a LC 50 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 e ffects may be minimal and/or short-term in duration; therefore, they may not require avoi dance or mitigation. Adverse impacts that are reduced by mitigation below the “significance thres holds” that are incorporated into the permit, or that are demonstrated to be acceptable becaus e the risk of the impact occurring is small, are considered “nonsignificant.” Fo r this evaluation, “significance threshold” is defined for each
resource as the level of effect that equals or exceeds the ad verse changes indicated in the following impact situations:

• Biological Resources (seals, walr us, 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 th at results in a declin e in abundance and/or change in distribution requiri ng 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 a nd Steller’s eiders): An adverse impact that results in a decline in abundance and/or ch ange in distribution requiring one or more generation for the indi cated population to recover to its former

status.ODCE for Arctic NPDES General Permit 1/24/06
4-3 4.1. PLANKTON

Plankton can be divided into two major classe s: phytoplankton and z ooplankton. Plankton are vital components of the pelagi c plankton community as they pr ovide the food base for other groups of marine organisms found within the Arctic Area of Coverage. The distribution, abundance, and seasonal variation of these orga nisms 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 a nd epontic habitats (MMS, 1991).
Chaetoceros sp. has also been identified as an abu ndant component of the phytoplankton (MMS, 1991). In studies done in Harrison and Prudhoe Ba ys, 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 (horizonta l) 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 S ea is generally greatest in nearshore waters, with decreasing abundance noted further offshore (MMS, 1990). Peak ab undance in late July and early August follows the breakup of winter ice and the peak in so lar 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 typi cal summer “blooms” during 1977 and 1978.

Phytoplankton production is limited primarily by av ailable nutrients, par ticularly nitrogen, and light. The most productive area of the Arctic Al aska waters is the co astal 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 af ter 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 aODCE for Arctic NPDES General Permit 1/24/06
4-4 seasonal spring phytoplankton bloom immediately following ice breakup has not been firmly established (Homer, 1984; Schell et al., 1982). However, this ma y 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 producti on is enhanced by the transport of upwelled
nutrient-rich water from the Gu lf of Anadyr in the northwest ern Bering Sea through the Bering
Strait and into the Chukchi Sea. An area of in tense productivity, nearly twice the production of the southeastern Bering Shelf, occurs in th e 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 lo w due to turbidity from the sediment load carried by the Yukon River. Primary productiv ity 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 phy toplankton growth are te mperature, 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 (Figur e 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 trophi c levels, too much phytoplankton can harm the overall health of the water body. During these bl ooms, most of the phytop lankton die and sink to the bottom, where they decompose. This proce ss 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.ODCE for Arctic NPDES General Permit 1/24/06
4-5 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 te rms of numbers and biomass (MMS, 1990). Other components of zooplankton include am phipods, mysids, euphausiids, chaetognathes, ostracods, pteropods, ctenophores, and larval stag es of benthic and nektonic organisms.

Zooplankton can be found in the sunlit zone a nd 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 typi cal summer “blooms” during 1977 and 1978.

The currents moving north through the Bering Stra it 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 an d fishes from the Bering Sea to the Chukchi Sea. Seasonal ice regimes also influence th e spatial and temporal variation of primary productivity.

Zooplankton standing stock generally fluctu ates in response to phytoplankton production. Productivity within th e Beaufort and Chukchi Seas decreases from nearshore to offshore waters and is considerably less than the productivity obse rved in comparable dept hs 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, carnivorou s species, including species of whales that feed on pelagic zooplankton (e.g., bowhead whale) (Figure 4-1).

Zooplankton, like phytoplankton, make excellent indi cators of environmental conditions because they are sensitive to changes in water qual ity. They respond to low dissolved oxygen, high nutrient levels, toxic contaminants, poor food quality or abundance and predationODCE for Arctic NPDES General Permit 1/24/06
4-6 4.1.2.4. Critical Areas or Habitats

Zooplankton abundance is generally lower in th e Chukchi Sea than in more southerly areas (Hope and Norton Basins). However, zooplankt on communities have been described as being
richer in the Chukchi Sea and west ern part of the Beaufort Sea th an in the eastern Beaufort Sea (east of approximately Barter Island) (MMS, 199 0). At present no important habitats or areas
have been identified.

4.1.3. Effects Analysis

An extensive review found no evidence of effect s 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 re duce 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 p ack 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 fixe d pattern of vertical distributi on in their habita t. Some of these plants inhabit the coast above high water ma rk, whereas others populate the intertidal zone
or the sublittoral zone. Macroa lgae 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 bi omass is most commonly limited by dissolved inorganic nitrogen, but can also be limited if high light attenu ation prevents adequate light reaching the bottom.

The distribution of kelp is lim ited by three main factors: ice gouging, sunlight, and hard substrate. Ice gouging restricts th e growth of kelp to protected areas, such as behind barrier islands and shoals. Sunlight re stricts 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 shallo w 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 th at characterized areas with suitable rocky substrate (Dunton et al., 1982).ODCE for Arctic NPDES General Permit 1/24/06
4-7 Attached macroalgae (primarily kelp) occur in state waters in nearshore and offshore barrier island areas containing suitable ro cky 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, Belved ere and Flaxman Islands, Demarcation Bay, Elson Lagoon near Point Barrow, near Konganevik Point in we stern Camden Bay, and Nuvagapak Lagoon. Macroalgae concentrations along th e Chukchi Seacoast not been fr equently encountered in the Chukchi Sea, possibly due to the lack of adequate substrates (r ock, cobble, and gravel). Kelp
beds have been noted about 20 km northeast of P eard Bay near Skull Cliff and in an area 25 km (13.5 nmi) southeast of Wainwright in wa ter 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 indica ted the predominance of the kelp, Laminaria solidungula

, but red algae and a diverse assemblage of bent hic invertebrates were also noted (MMS, 1990). Macroscopic red and green algae ha ve also been noted in Peard Ba y of the Chukchi Sea (Truett, 1984a).

4.2.1.2. Growth and Production

Arctic kelp grows fastest in late winter and earl y spring due to higher con centrations of inorganic nitrogen in the water column (ADNR, 1999). Sedi ments 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 environmen t that provides a divers e habitat for attached microalgae, invertebrates, and fish. However, relatively few inverteb rates (all polychaetous annelids and arthropods) and only si x species of fish were noted in conjunction with the algae at Skull Cliff (MMS, 1991).

Kelp at Boulder Patch was estimated to contri bute half of the annual primary carbon production (Dunton, 1984). Approximately 60 percent of the particulate organic car bon released to the environment originates from kelp which may be an important source of carbon to secondary producers in the community (Dunton, 1984). The onl y 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 expl ored. The areas of concentrated macroalgalODCE for Arctic NPDES General Permit 1/24/06
4-8 growth that have been iden tified include Skull Cliff, St effansson Sound (Boulder Patch), Stockton Islands, Flaxman Island, Demarca tion Bay, and Elson Lagoon, which may be considered important habitats or areas. Phillip s and Reiss (1985) have al so 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 diat oms and microflagellates, but centric diatoms and dinoflagellates may also be pr esent (Homer & Schrader, 1982).

While the mechanism of photosynthesi s in microalgae is similar to th at 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 mo re efficient access to water,
CO 2 , and other nutrients.

4.2.2.1. Distribution and Abundance

Attached microalgae occur in the epontic commun ity 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 area s not subjected to ice gouging and land fast ice, and where hard substrates suitab le for attachment occur (MMS, 1990). However, benthic algae have been noted in areas where rock substrates we re lacking, but these algal beds did not contain the diverse epilithic fauna that ch aracterized areas with suitable rocky substrate (Dunton et al., 1982).

Benthic microalgae occur in sediments and w ithin the macroalgal communities. Benthic microalgae may be a significant source of primary pr oductivity in nearshore areas, but in areas of kelp production, the contribution of benthic micr oalgae may be relatively small. Dunton (1984) estimated that benthic microalg ae 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 whic h controls the distribution, deve1opment, and production of the ice-algal assemblage (MMS, 1 990). 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.ODCE for Arctic NPDES General Permit 1/24/06
4-9 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 j uvenile and adult fishes (MMS, 1991) (Figure 4-2).

Epontic microalgae were estimated to contri bute 25 percent of the a nnual 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 habita ts or areas can be identified at present.

4.2.3. Effects Analysis

The types of material discharged during exploratory operations us ually include drilling muds and cuttings, although there are restric tions on these discharges in sha llow water, under ice, and near special kelp communities. Although the pe rmit allows for a 100-m zone of potential contamination, there is no eviden ce of the effects on kelp and s eaweed. Smothering of species within the 1,000-m seafloor area would occur and would have a dverse affects to species. However, recovery of the affect ed benthic communities likely w ould occur within 1-2 years after the termination of discharges.

Drilling muds can adversely affect marine lif e provided exposures are sufficiently long and concentrations sufficiently high. Effects can occu r due to chemical toxic ity, clogging of feeding or respiratory structures with particulates, smothering, and modifications of habitat. The most toxicologically important constituents of dr illing muds are aromatic compounds and heavy
metals.

The benthic community in the immedi ate vicinity of the dr illing 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 co mmunities 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 wi thin the proposed area of coverage which would receive deposition amounts detrimental to bentho s, 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 i ndicates that less than 0.0001 per cent of the tota l area proposedODCE for Arctic NPDES General Permit 1/24/06
4-10 for exploration by MMS and ADNR would potentially be adversely impacted. Solids deposition exceeding 1 cm (0.4 in) in thickness may be expe cted 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 th e long-term toxicological effect s of drilling muds and cuttings deposited on the seafloor. Of particular concer n are the impacts arising from chronic leaching of metals, hydrocarbons, and the most persistent bioc ides in drilling muds and cuttings deposited on the bottom. In addition, insuffici ent evidence exists to demonstrat e that data from short-term acute toxicity tests rev eal subtle adverse effects at the ecosy stem 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 rang es from microscopic (e.g., microinvertebrates ,<10 microns) to a few te ns of centimeters or more in length (e.g., macroinvertebrates, >50 cm). Benthic invertebra tes live either on the surface of bedforms (e.g., rock, coral or sediment - epibenthos) or within sedimentary deposits (i nfauna), and comprise several types of feeding groups (e .g., deposit-feeders, fi lter-feeders, grazers and predators). The principal benthic invertebrates found in the Ar ea of Coverage include oligochaete worms, isopods, mysids, amphipods, bivalves, priapulids, ch ironomid larvae, dipterans, and hermit crabs (Broad et al., 1978).

4.3.1. Distribution and Abundance

The distribution, abundance, and seasonal variati on of benthic species in the Arctic Alaska waters are strongly correlated with physic al factors (e.g., substrate composition, water temperature, depth, dissolved oxygen concentra tions, pH, salinity, sediment carbon/nitrogen ratios, and hydrography). Larger invertebra te communities are found in nearshore lagoons. These communities include animals living in the bo ttom (infauna), animals living on or near the bottom (epibenthic), and those which live in th e 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 a ll 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 ge nerally increase with depth, exce pt 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 numeri cal abundance, polychaetes ( Ampharete vega and Terebellides

stroemi ), bivalves ( Cyrotidaria durriana ), and small crustaceans (p rincipally amphipods) are the most abundant infaunal organisms on the continenta l shelf and slope of the Beaufort Sea (CareyODCE for Arctic NPDES General Permit 1/24/06
4-11 et al., 1974, pp. 565-680; Carey & Ruff, 1977, p. 510; Carey, 1978, p. 160). Ca rey et al. (1974) reported that polychaete worms co mprised up to 85 percent of the infauna at stations sampled on
the Beaufort Sea continental shelf.

Common epibenthic creatures (epifauna) found w ithin 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 inverteb rate biomass, especia lly in inshore areas. Populations of nearshore and inshore motile ep ifauna 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 importan t 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 associ ated species include soft corals (Eunephthya sp .) and sea
cucumbers (Psolus sp . and Cucumaria sp .). Epibenthic species abundance and distribution are typically quite variable with in the shallow water lagoons ne ar 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 exte nds 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 w ith 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 abunda nce of infaunal specie s (Braun, 1985, p. 67). Ice gouging continues out to about 40 m (131 ft) with decreasing intensit y. Diversity and biomass of infauna increase beyond this zone with distance offs hore, at least as far as the continental shelf boundary [200 m (656 ft)] (MMS, 1990). Few da ta are available regarding the benthic community inhabiting deeper waters within the Beaufort Sea Pla nning Area; therefore, it is not possible to identify the important species in this region or their distribut ions and abundances.ODCE for Arctic NPDES General Permit 1/24/06
4-12 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 thatresulted 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 condit ions. 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 comm unities can change in response to:

• nutrient enrichment lead ing 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 toxi cants derived from oil and gas activities;

• dislodged epifauna and infauna from traw ling and dredging which may result in the collection and mortality of a subs tantial invertebrate bycatch;

• the replacement of the existing benthic comm unity 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 biol ogical 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 depo sit-feeding benthic invertebrate s (bioturbators) helps to mix the sediment and enhances decomposition of organi c matter. Nitrification and denitrification are also enhanced because a range of oxygenated an d anoxic micro-habitats are created. Loss of
nitrification and denitrificati on (and increased ammonium efflux from sediment) in coastal systems is an important cause of hysteresis, whic h can cause a shift from clear water to a turbid state. The loss of benthic suspension-feeding macroinvertebrates can fu rther enhance turbidity levels because these organisms filter suspended particles including planktonic algae, and they
enhance sedimentation rate s through biodeposition ( i.e. voiding of their wastes and unwanted food).ODCE for Arctic NPDES General Permit 1/24/06
4-13 Changes in the macrofauna (and flora) causes cha nges in nutrient storage pools and in the flux of nutrients between microfauna (and flora) and m acrofauna and flora. Macrofauna are also important constituents of fish diets and thus ar e an important link for transferring energy and nutrients between trophic levels a nd driving pelagic fish and crus tacean production. It is for these reasons and others, that benthic invertebra tes are extremely important indicators of environmental change.

The nearshore waters provide habitat for a variety of benthic organisms whic h in turn serve as an important food source for birds and fishes that utilize state waters fo r feeding, spawning, and nursery areas. The primary prey organisms for fish, mammals [inc luding 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 sp ecies 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 n ear the Sagavanirtok River) is recognized as an important benthic habitat, primar ily due to habitat provid ed by hard substrates and associated algal beds. This area lies with in the adjacent state wa ters of the areas of

coverage.

4.3.5. Effects Analysis

Many benthic invertebrates are re latively sedentary and sensitive to environmental disturbance and pollutants. Drilling muds can adversel y 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 toxicologica lly important constituents of drilling muds are aromatic compounds and heavy metals.

Overall, larvae and planktonic organisms are appare ntly 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 immedi ate vicinity of the dr illing 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 effect s of various depositi on depths on benthic communities. Most studies that have investig ated deposition impacts on benthos have examined deposition of dredged materials (Hale, 1972; Kran z, 1974; Mauer et al., 1 978; Oliver & Slattery,ODCE for Arctic NPDES General Permit 1/24/06
4-14 1973; Saila et al., 1972; Schafer, 1972; Schulen berger, 1970; Wilber, 1992). These studies indicate that the response to de position 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 imp acted 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 b ecause they would receive greater than 1 cm of deposited solids.

It is not possible to accurately predict the area wi thin the proposed area of coverage which would receive deposition amounts detrimental to bentho s, 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 i ndicates that less than 0.0001 per cent of the tota l 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 expe cted 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 th e long-term toxicological effect s of drilling muds and cuttings deposited on the seafloor. Of particular concer n are the impacts arising from chronic leaching of metals, hydrocarbons, and the most persistent bioc ides in drilling muds and cuttings deposited on the bottom. In addition, insuffici ent evidence exists to demonstrat e that data from short-term acute toxicity tests rev eal subtle adverse effects at the ecosy stem level of biological complexity (Parrish & Duke, 1990).

The quantity of benthic organisms preyed upon by ot her 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 altera tion of sediment grain size characteristics. The degree of food supply reduc tion caused by discharges of dr illing muds and cuttings is unknown, as the size of the affected area and sever ity of impacts are by ne cessity 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 th e Area of Coverage (approximately 0.0001 percent of the area) would receive deposition depths gr eater than 1 cm (0.4 in).

Benthic organisms near Beaufort Sea drilling si tes 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 te mporarily by drilling disc harges, 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 likel y 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 co mposition of affected bent hic areas. Recovery of the affected benthic communities likely would o ccur within 1-2 years after the termination of discharges.ODCE for Arctic NPDES General Permit 1/24/06
4-15 Norton Sound supports a rich benthic community wh ich plays a key role in an extended food chain supporting a wide range of marine mammals. Any disrupti on of this benthic base could seriously affect the biot a of the entire region.

4.4. FISHES

The fishes occurring in the Arctic Alaska wate rs fall into three basic categories (MMS, 2003): 1) freshwater species that may occasionally ente r marine waters, 2) anadromous species that spawn in freshwater and migrate seaward as juve niles 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). Seve nty-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 a nd spatial distribution and abunda nce of fish (MMS, 1990, 1991). The Chukchi Sea represents a transition zone be tween the fish communities of the Beaufort and Bering Seas (MMS, 1991); the fauna is primarily Arctic with conti nual input of southern species through the Bering Strait (Craig, 1984). Marine fish in the C hukchi Sea are generally smaller
than those in areas farther s outh, and densities are much lowe r (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 n earshore 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 (m arine 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 res ources than waters farther offs hore. The areas of greatest species diversity within the nearshore zone are th e river deltas. As the summer progresses, the amount of freshwater entering the nearshore zone decreases, and n earshore waters become colder and more saline. From late summer to fall, migr atory fishes move back in to 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 duringODCE for Arctic NPDES General Permit 1/24/06
4-16 high-water years (MMS, 2003). Th e distribution and abundance of freshwater and migratory fishes depend on (1) adequate overwintering area s, (2) suitable feeding and spawning areas, and (3) access to these areas (typical ly provided by a network of in terconnecting waterways) (MMS, 2003).

Since the presence of freshwater species is ge nerally sporadic and brief within the Area of Coverage, there is little information regard ing distribution and abunda nce, 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 habita ts 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 ne arby (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, th ese fish will migrate along the coast; smaller fish tend to stay near the mouths of rivers while larger fish may migrate distance s 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, wher e they spawn and overwin ter, by mid-September (ADNR, 1999).

Whitefish spend much of their life cycle feedi ng in salt water during th e 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 th e 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 coas tal waters, particularly
east of the Colville River. While the occurren ce 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 th e Colville River. However, both species do not have established populations and spawning is not know n 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, 20 03). 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 wi dely distributed but in fairly low densities; schooling species (e.g., arctic cod) display a rather pa tch distribution (ADNR, 1999). Some marine species sporadically enter the nearshore areas to feed and spawn while others remain in coasta l waters throughout the open-water season then move farther offshore w ith the advancement of the landfast ice during
winter.ODCE for Arctic NPDES General Permit 1/24/06
4-17 The most widespread and abundant marine speci es are the arctic cod, saffron cod, twohorn and fourhorn sculpins, the Canadian eelpout, and the arctic flounder (MMS, 1987a). Additionally, Arctic staghorn sculpin, short horn sculpin, and hamecon are abunda nt species in the Chuckchi
Sea

. Common marine fishes in the nearshore area include fourhor n sculpin, yellowfin sole, and capelin (MMS, 1987b, 2003). Saffron cod, arctic flounde r, 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, a nd fourhorn sculpin are generally found in the lowsalinity waters near estuaries and river mouths. Common marine fishes in waters farther offshore include arctic cod, arct ic staghorn sculpin, kelp sna ilfish, capelin, shorthorn sculpin, twohorn sculpin, hamecon, and Canadian eel pout (MMS, 1987a, 2003). Despite the large quantity of benthos in Norton Sound, bottomfish ar e less abundant there than in the other Alaskan regions in the Area of Coverage.

Arctic cod are infrequent visitors to nearshore habitats during th e first portion of the open-water
season when waters are warmest and salinities ar e low (Craig et al. as cited in MMS, 2003).
Arctic cod have been found to be more con centrated 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 virtua lly all nearshore habitats, including deeper waters not frequented by anadromous fishes.

Saffron cod, arctic flounder, and starry flounde r have similar distributions; however, their occurrence is sporadic and variable and they ar e 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 pa tchy in its distribution (ADNR, 1999).

Capelin is a widely distributed species that ha s 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 ar ctic fish populations (ADNR, 1999).

Ocean growth of pink salmon is a matter of considerab le interest because, although this species has the shortest life span among Pacific salmon, it also is among the fa stest growing. Entering the estuary as fry at around 3 cm in length, maturi ng 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 sitesODCE for Arctic NPDES General Permit 1/24/06
4-18 can meet this requirement, spawning often take s 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 th eir eggs to rocks or ke lp. 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 ma rine fishes are similar to those of anadromous fishes, some marine fishes are believed to compete with migr atory fishes for the same prey resources. Competition is most likely to occur in the nearshor e brackish-water zone, particularly in or near the larger river deltas.

Infaunal prey density in the nearshore substrat e is very low and provi des little to no food for anadromous fishes. However, prey density in the nearshore water colu mn is high, about five
times that of freshwater habitats on the Arctic Co astal Plain. The nearshore feeding area also is much larger than that of freshwater habita ts on the coastal plain (MMS, 2003). For these reasons, both marine and anadromo us 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. Anadromo us fishes do little to no feeding during their migration back to freshwater and when spaw ning, but some resume feeding during winter.

In the marine environment, pink salmon fry and j uveniles are food for a host of other fishes and coastal sea birds. Subadult and adult pink sa lmon are known to be eaten by fifteen different marine mammals, sharks, other fishes such as Pacific halibut, and hum pback whales. Because pink salmon are the most abundant salmon in the No rth Pacific, it is likely they comprise a significant portion of the salmonids eaten by marinemammals.

Marine species feed heavily on epibenthic and plankt onic 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 z ooplankton), all other offshore fish species rely heavily on benthi c invertebrates, particularly amphipods and polychaetes (MMS, 1984).

The arctic cod has been described as a key specie s in the ecosystem of the Arctic Ocean due to its widespread distribution, abunda nce, and importance in the diet s of marine mammals, birds,
and other fishes. It is consider ed to be the most significant c onsumer of secondary production inODCE for Arctic NPDES General Permit 1/24/06
4-19 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 anad romous fish species (ADNR, 1999). During the open-water period, ci sco undertake extensive migrations through the nearshore area (ADNR, 1999). Most marine specie s 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 arct ic cod (Cannon, Glass, & Prewitt as cited in MMS, 2003). Fourhorn sculpin spawn on the bottom in nearshore habi tats during midwinter (ADNR, 1999). Snailfish attach their eggs to rocks or kelp stub strates in nearshore waters (MMS, 1987a).

Pink salmon and rainbow smelt use larger river sy stems and estuaries in the area, such as the Kokolik, Utukok, Kukpowruk, and Kuk, as spawning a nd 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 th e 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 u nknown (Morris, 1981). Arctic cod are most often found around pressure ridges and raft ed ice, where the undersurface of the ice is rough (MMS, 1991). Typical habitats include crev ices, 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 densitie s 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 diss ipating tidal or current action. Discharges in shallow, ice-covered waters are presently restricted ; therefore, the likelihood that fishes would be exposed to discharges during th eir 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 spec ies, including most co ttids and eelpout, possess demersal eggs. Although unlikely during explorator y 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 ad versely impact demersal fish spawning activitiesODCE for Arctic NPDES General Permit 1/24/06
4-20 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 dr illing to fish species.

Drilling mud disposal is not expe cted to affect the major prey, zooplankton, or fish or their habitats. Discharges of drilling fluids and dr illing cuttings may imp act minor prey, benthic organisms (at sublethal levels), a nd benthic habitat, which in turn will impact critical habitat for fish species. Drilling discharges could displace fishes a short di stance from the source however, the effects would be localized and temporary. Ho wever, the impact areas are small (less than 100-m radius) per discharger, the number of disc harges is small (23 e xploration wells and 14 delineation wells), and the recovery period of impacted benthos is less than two years. It is expected that fishes would re-u tilize their habitat upon completion of the exploration activities.

4.5. MARINE MAMMALS

Marine mammals in the Area of Coverage include polar bears, walrus, a nd species of seals and whales. Common species include: spotted, ringe d, 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 (i ncluding 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 prot ected under the Marine Ma mmal 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 comm ensurate with sound policies of resource management, and that the primary objectiv e 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., Inte rnational Agreement on the Cons ervation 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 b earded seals and polar bears; seasonal summer species include the beluga whale a nd the spotted seal. Gray whales and walrus also reside seasonally within the Beaufort Sea, mo st often in areas west of Barrow. Most of the marine mammals occurring in the Chukchi Sea ca n be grouped into two categories: 1) baleen whales that use the area as summer feeding grou nds, and 2) pinnipeds (seal s and walrus) that are ice-associated during the winter a nd 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 ma y 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 predic t populations at any gi ven time or location. AODCE for Arctic NPDES General Permit 1/24/06
4-21 seasonal distribution of marine mammals in the northeastern Chukchi Sea is summarized below (Morris, 1981, pp. 56-57). Some species of pinnipe ds occur in great abundance in the Chukchi Sea, with densities as high as 2-3 seals/km 2 not uncommon in the la ndfast-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) walr us, seals, gray whale, beluga whale

Coastal Lagoons: beluga whale, spotted seal

Note: The flaw zone is that region between the pack ic e 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 hist orical 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 la te as July (MMS, 2003). An estimated 2,500-3,000 belugas summer
in the northwestern Beaufort a nd Chukchi Seas; some use coastal areas. Fall migration back to the Bering Sea occurs in September and Oc tober 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 popul ation 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, 2 003). 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 haveODCE for Arctic NPDES General Permit 1/24/06
4-22 been observed up to 200 km offshore (Bonnell & Dailey as cited in MMS, 2003). Much of the migration route north of Point Conception to a nd from summer feeding grounds in the northern Bering and southern Chukchi seas lies within a fe w kilometers of the coast or adjacent islands. Nearly all gray whale observations were west of Point Barrow, and few gr ay 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 Beaufo rt 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 cu rrent stock assessment is 2,272 and a minimum estimate of 1,971 bears ( Federal Register March 28, 2002). This popula tion has increased over the past 20-30 years at 2% or more per year a nd is believed to be increasing slightly or stabilizing near its carrying cap acity (Amstrup; US Fish & Wild life 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 c oncentration areas. Much lowe r densities occu r beyond 100 miles offshore and higher densities near ice leads, wh ere seals concentrate dur ing 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, & Lent fer 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. Lawr ence Island. The approximate nu mber of polar bears which
occur in the Norton Basin is unknown.

The ringed seal ( Phoca hxspida ) is the smallest and most abunda nt seal in the Beaufort and Chukchi Seas. Ringed seals live on or near the ice year-round; th erefore, the seasonal ice cycle has an important affect on their distributi on and abundance (ADNR, 1999). More recently, surveys were flown perpendicular to the Alaska n coast from Shishmaref to Barrow during MayJune 1999 and 2000 (Angliss & Lodge, 2002). Prelim inary 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 th e 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 th e 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 Pear d 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 coasta l haulout areas include the Colville River delta, Peard Bay, and Oarlock Island in Dease Inlet/Adm iralty 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.,ODCE for Arctic NPDES General Permit 1/24/06
4-23 2000). The Bering Chukchi population of spo tted seal ranges from 280,200 go 330,000. Major population segments migrate through outer No rton 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 c onsistently show slightly more females in the population (ADNR, 1999). This sp ecies usually prefers areas of less-stable or broken sea ice, where breakup occurs early in th e year (Cleator & S tirling 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 minimu m population in Alaskan waters is expected to be at least 50,000 animals (Ferrero et al. as ci ted in MMS, 2003). From 300,000 to 450,000 bearded seals inhabits the Bering and Chukc hi 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 usua lly 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 mo ve east throughout the Alaskan portion of the Beaufort Sea to Canadian waters during the open wa ter season. Walrus are very abundant in the Chukchi Sea during the summer; over 100,000 indivi duals, or 40 percent of the North Pacific population, can be found there (Sea se & Chapman, 1988). Of this number, most are pregnant females and their dependent young. About 80 percent of the worl d population (160,000 to 200,000) occurs seasonally in the Bering Sea. During seasonal transition periods, walrus densities are greatest in outer Norton Sound. Ca lves are born during the northward migration in spring in outer Norton Sound. A substantial numbe r of the mature males remain in the Bering Sea year-round (Fay, 1982). Solitary animals occas ionally 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 advancemen t 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 in creased walrus abundance (Fay et al., 1984).

4.5.2. Growth and Production

Beluga whale calving is reported to o ccur in Norton Bay near Moses Point.

Polar bears breed during April and May. Males tr avel long distances duri ng 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 occursODCE for Arctic NPDES General Permit 1/24/06
4-24 anytime from early April to the first part of Ma y with the peak season being the first two weeks of April.

The ability for bearded seals to conceive successfu lly 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, 199 9). Females bear a single pup during late April or early May. Pupping takes place on top of th e ice less than 1 m from open water (Kovacs, Lyderson, & Gjertz as cited in MMS, 2003) from late March th rough May mainly in the Bering and Chukchi seas, although some takes place in th e Beaufort Sea. By the end of a brief nursing period (12 to 18 days), pups increa se their weight almost three times, mainly due to an increase in thickness of the blubber laye r (ADF&G as cited in ADNR, 1999).

The gross reproductive rate of walruses is cons iderably lower than that of seals. Prime reproductive females produce one calf every 2 ye ars 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 mi d-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 C hukchi and Beaufort Seas during spring to feed throughout the late spring, summer, and early fa ll. Gray whales are primar ily suction-bottom feeders and primarily ingest benthic gamma ridean amphipods (MMS, 1991). However, gray whales have also been observed feeding on dense swarms of pelagic euphaus ids (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 near shore waters (MMS, 2003). The majority of the eastern Pacific gray whale popul ation feeds primarily on benthic amphipods; they suck infauna amphipods from the fine sand on th e ocean bottom, producing an extensive record of feeding craters 2-20 square meters (m 2 ) in size (MMS, 2003).

For polar bears, successful denning, birthing, an d 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 s ea 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 lo cally, and is not dependent on reproduction from other known denning areas outside of the region (Amstrup & Gardner as cited in ADNR, 1999).ODCE for Arctic NPDES General Permit 1/24/06
4-25 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 po lar bears concentrate near open leads in winter. A polar bear has to catch approximately on e seal a week to maintain itself. The mother does not eat while denning; both she and he r cubs live off her fat reserves.

Seals feed primarily on pelagic fishes and invert ebrates; the particular species eaten depends on availability, depth of water, a nd distance from shore. Ringed seals spend much of the summer and early fall in the water feed ing; 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 diffe rences in their prey. Princi pal foods for spotted seals are schooling fishes and along the coast they f eed 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, cl ams and snails (ADF&G as cited in ADNR, 1999).

Walruses feed primarily on bottom dwelling inve rtebrates by brushing the sea-bottom with their brad, flat muzzles. Major food items include biva lve 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 C hukchi seas provide important habitat areas for a variety of marine mammals. Thes e areas include denning areas for polar bears, haulout areas for walrus and species of seals, and feedi ng areas for gray and beluga whales.

A major portion of the Beaufort Sea beluga wh ale 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 Beaufo rt seas provide rich benthic feeding habitat for gray whales duri ng 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 highe st secondary production rates reported for any extensive benthic community (R ugh 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 regi ons including the Jones Island group, offshore and barrier islands, shorefast ice, along river banks , and far offshore on th e pack ice (MMS, 1991). An important habitat zone is in the eastern Beaufo rt 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 certa in portions of the mainland (MMS, 1990); areas receiving consistent use include Wrangell Isla nd, Russia, and in Hudson Bay and James Bay,ODCE for Arctic NPDES General Permit 1/24/06
4-26 Canada. Polar bear dens have also been lo cated 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 hab itat for ringed seal lair cons truction and supports the most productive pupping areas (Kelly, 198 8). Regions of landfast ice ar e found in the southeastern corner of the Chukchi Sea Area of Coverage.

During the summer, two large Arctic areas are oc cupied by the walrus: from the Bering Strait west to Wrangell Island and along the northwest coas t of Alaska from about Point Hope to north of Point Barrow. Although the Pacific walrus is associated with movi ng pack-ice, a coastal walrus haulout area east of Cape Lisburne in the Chukchi Sea was id entified (MMS, 1990). Herds of migrant walrus appear on Big Diomed e, 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 Fair banks (Dehn et al., 2002). The st udy 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) an d bearded seals eat benthic and epibenthic organisms. The variations were observed over broa d 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 th e 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 th e 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 C hukchi Sea area. Most of these species are migratory and only present in the Arctic seas onally, from May through early November. Some species appear only during migratio n; others nest, molt, feed, and accumulate critical fat reserves needed for migration while in the area (MMS, 1 987a). The main categories of species in the Area of Coverage include wate rfowl (e.g., duck, goose, swan), seabirds (e.g., loon, gull, tern), shorebirds (e.g., sandpiper, plover, crane), and rapt ors (e.g., hawks, eagles, falcons). A complete list of all bird species within these groups for the Area of Covera ge is presented in Tables 4-2 through 4-5.ODCE for Arctic NPDES General Permit 1/24/06
4-27 4.6.1. Distribution and Abundance

Aerial surveys in the Beaufort Sea have documen ted that birds are widespread in substantial
numbers in both nearshore and o ffshore waters of the Area of C overage (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, th e highest bird density is associated with openwater leads, where more than 1 million eide rs 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 Beri ng 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 broa d 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 de ltas and in leads determines migratory routes and distribution of waterfowl and seabirds. Rapt ors 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 Barro w 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 norther n Bering Sea are least au klet, 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 concen trated on a few breeding coloni es primarily on St. Lawrence and Little Diomede Islands. The parakeet aukl et is widely distribute d with small colonies located along the coast of Nort on Sound and larger colonies present on the offshore islands. The
common and thick-billed murres ar e widely distributed with br eeding populations on both the offshore islands and along the coast of Norton S ound. Thick-billed murres generally concentrate on offshore islands and shelf break areas, while co mmon murres are found more in coastal areas. Black-legged kittiwakes are also widely dist ributed 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. S cattered colonies of brant oc cur through northwest Alaska, particularly from Smith Bay west to the C hukchi coast, and low numbers southward to Kasegaluk Lagoon (MMS, 2003). The Yukon-Kuskokw im River Delta has the greatest nesting
concentrations of waterfowl a nd shorbirds in the Norton Basin with other important nesting, feeding, and staging areas occurr ing along the coast of the Seward Peninsula and St. Lawrence
Island.ODCE for Arctic NPDES General Permit 1/24/06
4-28 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 re gion. 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 migran ts along the coast of the Arctic National Wildlife Refuge, although oldsquaws are widespr ead 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 molti ng 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 barri er 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 re gion (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 co astal lagoons (MMS, 2003) before moving south to wintering areas begi nning in late August and continuing into early November. Male king eiders undertake a molt mi gration 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 co astline, nonincubating members of shorebird pairs concentrate in coastal habitats as early as mid-J une. In late June to early July, several species move to habitats surrounding sma ll coastal lagoons and nearby brack ish 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 Co astal Plain have shown that most waterfowl and other waterbird species have exhibited nonsignificant popul ation trends since 1986 or 1992 (MMS, 2003), although there is conflicting eviden ce for some species. Pacific loons, glaucous gulls, northern pintails, greater scaup, whitewinged scoters, brant, snow geese, a nd 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-front ed goose and arctic tern increased significantly. Although the population of oldsquaw ducks on the Arctic coastal plain
of Alaska has remained relative ly stable, populations in Northwes t Canada and other regions in Alaska have declined 75 percent.ODCE for Arctic NPDES General Permit 1/24/06
4-29 Up to 7,500 snow geese nest on th e 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 offs hore 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/km 2 ; common eider numbers were 3,300 (June/July) and 1,477 (August), with densities from 4.6 (June/July) to 56.4 (August) birds pe r square kilometer. Generally, fewer than 1,000 Pacific loons, 200 re d-throated loons, and 100 yellow-billed loons were present in this area at very low densities.

The highest breeding-season densities for 34 specie s in an area east of Prudhoe Bay ranged from 251.7 birds per square kilometer in the second w eek of June to 167.0 in mid-July, and 131.7 in mid-August. Most abundant were Lapland l ongspurs and several sh orebird species (Troy Ecological Research Assocs . as cited in MMS, 2003).

Norton Sound has a relatively small seabird populati on with the largest con centration in the Bluff Cliffs area east of Cape Nome. Large populatio ns of common murre are found in this area and on Sledge Island. The larges populations of bl ack-legged kittiwakes occur on St. Lawrence and Little Diomede Islands with sizable populations on King Island, Bluff Cli ffs, Sledge Island, and Cape Denbigh (MMS, 1982).

About 11.6 million waterfowl, including approx imately 30 percent of North America’s goose population, nest in the Bering S ea region (King & Dau as cite d in MMS, 1982). The highest total densities of all waterfowl species (400 nest s 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 leas t twelve breeding species (about 9,000 ducks, geese, and swans) nest and an additional 25,000 nonbreeding waterfow l 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 pr ovides a long but narrow front of open water which is utilized by millions of birds in their mi gration to nesting grounds. Nearly all of the king eider population of Alaska and Ca nada, as well as thousands of olsquaws and common eiders, use this lead system (Sousa as cited in ADNR, 1999). Major con centrations of birds occur in nearshore and coastal areas such as the Plover Isla nds 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. Isla nds in river deltas and barrier islands provide the principal nesting hab itat for several waterfowl and mari ne bird species in the Area of Coverage. Shorebirds prefer we t-tundra habitats or well-drain ed gravelly areas for nesting,ODCE for Arctic NPDES General Permit 1/24/06
4-30 whereas loons use lakes, and geese prefer deep er ponds or wet tundra near lakes. Lagoons formed by barrier islands, bays, and river delt as provide important br oodrearing and staging habitat for waterfowl, particularly molting oldsquaw s. 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 surroundi ng 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, especi ally lagoon margins, are used extensively by red phalaropes at this time.

Emergent and wetland vegetation such as variou s sedges are the primary food types for most waterfowl. Invertebrates in brackish and fr eshwater flats and ponds are the principal food sources for shorebirds. Phalaropes, terns, a uklets, 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 su ccess of black-legged k ittiwakes is greatly dependent on the availability of sand lance during the chick-rear ing 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-c rowned night heron is an opportunistic feeder; its diet consists main ly of fish, though it is frequently rounded out by other items such as leeches, earthworms, aquatic a nd terrestrial insects. It also eats crayfish, mussels, squid, amphibians, lizards, snakes, rodent s, 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 s upporting a variety of marine and coastal avifauna include the barrier islands, coas tal lagoons, coastal saltmarshes, rive r deltas, and offshore areas. The coastal waters are primary habitat for ne sting, molting, feeding, and resting activities of migratory marine birds. Coasta l tundra and delta areas are al so 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 occu r 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 Layand Kasegaluk Lagoon, Peard Bay, Plover Islands-Barrow Spit and Elson Lagoon, Pitt PointCape Halkett, Fish Creek Delta, Colville Rive r Delta, Simpson Lagoon, the barrier islands of Prudhoe Bay, Canning River delta, Yukon River delta, Hulahula Ri ver delta and Barter Island, St. Lawrence Island, Little Diomede Island, St. Matthew Island, Beaufort Lagoon, Icy Reef, and Demarcation Bay.ODCE for Arctic NPDES General Permit 1/24/06
4-31 The Colville, Sagavanirktok, Canning, and Hu lahula river deltas, Simpson Lagoon, and the Arctic National Wildlife Refuge (Capes Thom pson and Lisburne, the Kasegaluk Lagoon and Peard Bay barrier islands, Icy Cape, and Point Franklin) provide importa nt nesting habitat for loons, waterfowl, and shorebirds and include fo raging habitat for seabir ds nesting in these regions. Along the coast of the Seward Peninsula, most lagoons, deltas, river mouths, and coastal tundra are used by waterfowl and shor ebirds for feeding, stating, molting, or nesting during some part of the year. The greatest con centrations 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, includ ing gulls, terns, and eiders, ne st 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 Du ck islands in the Sagavanirktok River Delta; snow geese also nest on the Ikpikpuk River de lta 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 populat ion 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 breed ing and brood-rearing habitats for tundra swans, black brant, snow geese, and Canada geese. Howe Island, located in the Sagavanirktok River delta, is th e location of one of two known s now gooses nesting colonies in the United States and is important for black bran t nesting (Sousa as cite d in ADNR, 1999). The Plover islands, such as Cooper and Deadman Is lands, are important nesting grounds for black guillemont. The Colville River from Umiat to O cean Point, and Franklin and Sagwon Bluffs in the Sagavanirktok River drainage are primary nesting areas fo r the Arctic peregrine falcon.

Common eiders, glaucous gulls, and arctic tern s nest on barrier islands in the east-central
Beaufort Sea in addition to on other islands a nd 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 Poin t Thomson (MMS, 2003). The Return Islands, Jones Islands, McClure Islands , Cross Island, and Lion Point ar e important for nesting common eider. Black guillemots nest mainly on barrier islands in the western Beaufort, particularly Cooper Island (Divoky, Watson, & Bartonek as cite d 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 al so found nesting and rearing in th e major river deltas and other coastal plain areas (Ott as cited in ADNR, 1999).

Shorebirds use a range of habitats from dry gravel ly to wet tundra and litt oral. Important feeding and staging grounds for shorebirds and waterfoul include Kasegaluk Lagoon, the mouth of the Kuk River, Peard Bay, and saltmar shes along the mainland coast. These habitats are critical to waterfowl that regularly pass through or near the Beaufort an d Chukchi Seas during migration.

Major concentrations of molting waterfowl o ccur in several areas along the Beaufort and Chukchi sea coasts including Simpson Lagoon, th e Teshekpuk Lake Special Area, Peard Bay, Kasegaluk Lagoon, and Ledyard Bay from late June through August. Postmolting and broodrearing brant use various coas tal habitats such as sloughs a nd tidal flats from early JulyODCE for Arctic NPDES General Permit 1/24/06
4-32 through August (MMS, 2003). Snow goose brood rearing 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 vulne rability to potentially adverse factors associated to a large ex tent with oil and gas exploration. Discharges from drilling operations during exploration typi cally disperse rapidly in the surrounding water, although some may be deposited on the bottom near drill si tes. 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 pr ojected drill sites under this general permit. Additionally, drill st ructures are likely to be quite disp ersed (MMS, 2003). Thus, discharges are not likely to cause significant effects either throu gh direct contact with birds or by affecting prey availability as a result of the authorized discha rges. In addition, there is likely sufficient time between discharges at individua l sites for regional bi rd 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 ag encies to consult with the U. S. Fish and Wildlife Service (USFWS) and th e National Marine Fisheries Se rvice (NOAA Fisheries) if the federal agency’s actions could be neficially 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 jurisdicti on of both the USFWS and NOAA Fisheries. This evaluation identifies the endangered, threatene d, and proposed species and critical habitat in the project area and assesses potenti al effects to these species that may result from the discharge authorized in the proposed final NPDES permit.

The federal action under discussion in this documen t 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 discha rged and the potentially toxic components of drilling muds (e.g., metals). Other minor polluta nt sources which are pot entially of concern and
were considered in this evaluati on are: deck drainage, sanitary waste, domestic waste, and test fluids. A more complete discussion of thes e waste streams can be found in Section 2.0. Additional permitted waste streams were not consid ered 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 summa ry of these species status is provided in Table 4-6. Ta ble 4-7 indicates which species have critical habitat designations. TheODCE for Arctic NPDES General Permit 1/24/06
4-33 remaining sections of this chapter will discuss th e abundance, distribution, diet, critical habitat, and effects for listed species occu rring in the Area of Coverage.

4.7.1. Short-tailed Albatross

The short-tailed albatross is listed by the USFWS as Enda ngered 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 fo rty 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-tail ed albatross bred on a number of Japanese islands, and its range
extended to most of the north Pacific Ocean in cluding 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 albatr oss 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 with in the Area of Coverage to feed.

4.7.1.2. Diet

The short-tailed albatross eats flyi ng 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 isla nds. 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 a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in th e discharged muds. Events serious enough toODCE for Arctic NPDES General Permit 1/24/06
4-34 cause a decline in population abundance, with re spect to permitted discharges, include the following:

• Discharged muds and cuttings were ingested directly;

• Consumption of prey contaminated by dril ling muds in numbers sufficient to cause lethality or a decline in reproductive fitness; and

• Decline in prey populations due to toxic e ffects of discharged muds and cuttings.

Seasonal distribution of the spectacled eiders dete rmines their vulnerability to potentially adverse
factors associated with oil a nd 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 th at exploration operations will occur in the Area of Coverage where the short- tailed albatross is found, it is un likely 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 th reatened under ESA thro ughout 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 th e Canadian border. They also nested along much of the arctic coast of Russia. Today, two pr imary nesting grounds remain in Alaska; the central coast of th e Yukon-Kuskokwim Delta, and the ar ctic coastal plain. A few pairs nest on St. Lawren ce 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 4,00 0 pairs nest there today. An estimated 7,371 spectacled eiders (about 2 percen t of the world population) seas onally occupy the arctic coastal plain (MMS, 2003) each summer. Breeding densiti es decrease from west to east (MMS, 2002). Population trends for spectacled ei der on the arctic coas tal plain are unclear, and survey data may reflect timing of surveys rather th an 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 i ndividuals have been observed at one time (MMS, 2002). Molting flocks gath er in relatively shallow coastal water, usually less than 36 m (120 ft) deep. Males leave the breeding grounds as incubation begins, us ually around mid-June, and begin a molt migration, stopping in bays a nd lagoons to molt and stage for fall migration.ODCE for Arctic NPDES General Permit 1/24/06
4-35 Females whose nests failed leave the nesting area to molt at sea by mid-August. Breeding females and their young remain on the nesting gr ounds until early September. While moving between nesting and molting areas, spectacled eide rs travel along the coast up to 50 km (31 mi)
offshore.

Wintering flocks of spectacled ei ders, possibly the enti re population, have been observed in the Bering Sea between St. Lawrence a nd 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 floc ks in openings of nearly continuous sea ice.

4.7.2.2. Diet

Spectacled eiders feed on bottom-dwelling mollu scs 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 (mo lting areas) for spectacled eider, which includes
four areas: the Yukon-Kuskokwim delta and ad jacent 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 vegetatio n appear to be importa nt 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 a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in th e discharged muds. Events serious enough to cause a decline in population abundance, with re spect to permitted discharges, include the following:ODCE for Arctic NPDES General Permit 1/24/06
4-36 • Discharged muds and cuttings were ingested directly;

• Consumption of prey contaminated by dril ling muds in numbers sufficient to cause lethality or a decline in reproductive fitness; and

• Decline in prey populations due to toxic e ffects of discharged muds and cuttings.

Seasonal distribution of the spectacled eiders dete rmines their vulnerability to potentially adverse
factors associated with oil a nd 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. Be cause 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 lo cal drill-site areas or re ly specifically on prey
affected or buried in such areas. Additionall y, drilling structures are expected to be quite dispersed throughout the area of co verage (MMS, 2003). Thus, discha rges are not likely to cause significant effects either through dire ct contact with birds or by a ffecting prey availability as a result of the discharges authori zed by the general permit. The mi nor effects that may result from individual dischargers are not li kely to substantially elevate th e current nonsigni ficant rate of
decline.

No direct impact from the disc harge 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 allowa ble discharges of drill ing muds and cuttings.

Feeding habitats for the endange red or threatened bird spec ies are probably not found at permanent locations. Also, feeding by these bird sp ecies typically occurs close to shore, in water depths where discharges are typically restricte d. Available information suggests that permitted discharges from oil and gas dril ling and other associated activiti es are unlikely to destroy or adversely modify habitats critic al 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 no t 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.ODCE for Arctic NPDES General Permit 1/24/06
4-37 4.7.3.1. Abundance and Distribution

Steller’s eiders are diving ducks that nest in the terrestrial envi ronment, but spend most of the year in shallow, near-shore marine waters. Th ey 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 nor thern population occurred from Wainwright east to near the
Alaska-Canada border and the we stern 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 abunda nce and distribution of the western population is not know n, but by the 1960s or 70s, the sp ecies 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. Lawren ce Island since 1954.

Steller’s eiders in Alaska nest on tundra adjacen t to small ponds or within drained lake basins, generally near the coast but rang ing 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 Rese rve-Alaska and on privat e 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. Wh ile 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 co astal 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 pair s 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 spri ng migration, the Alaska-breeding population intermixes with the larger Russi an-Pacific population in the marine waters of southwest Alaska. Concentrations of molting Steller’ s eiders have been observed n ear 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 st aging 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. Ov erall, the worldwide population of Steller’s eiders may have decreased by as much as 50% over the last 30 years.ODCE for Arctic NPDES General Permit 1/24/06
4-38 4.7.3.2. Diet

The Steller’s eider diet includes crustaceans and mollusks. While nesting, they feed on aquatic insects and plants in fres hwater ponds and streams

4.7.3.3. Critical Areas or Habitats

The USFWS designated critical habitat for Stelle r’s eiders, which includes nesting areas on the
Yukon-Kuskokwim delta and areas on the north si de 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 id entified as being importa nt to the survival and recovery of the Alaska-breeding population.

4.7.3.4. Effects Analysis

Endangered or threatened species may be a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in th e discharged muds. Events serious enough to cause a decline in population abundance, with re spect to permitted discharges, include the following:

• Discharged muds and cuttings were ingested directly;

• Consumption of prey contaminated by dril ling muds in numbers sufficient to cause lethality or a decline in reproductive fitness; and

• Decline in prey populations due to toxic e ffects of discharged muds and cuttings.

Seasonal distribution of the Stelle r’s eiders determines their vulne rability to potentially adverse
factors associated with oil a nd 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. Be cause 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 lo cal drill-site areas or re ly specifically on prey
affected or buried in such areas. Additionall y, drilling structures are expected to be quite dispersed throughout the area of co verage (MMS, 2003). Thus, discha rges are not likely to cause significant effects either through dire ct contact with birds or by a ffecting prey availability as a result of the discharges authori zed by the general permit. The mi nor effects that may result fromODCE for Arctic NPDES General Permit 1/24/06
4-39 individual dischargers are not li kely to substantially elevate th e current nonsigni ficant rate of
decline.

No direct impact from the disc harge 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 allo wable discharges of dr illing muds and cuttings.

Feeding habitats for the enda ngered or-threatened bird spec ies are probably not found at permanent locations. Also, feeding by these bird sp ecies typically occurs close to shore, in water depths where discharges are typically restricte d. Available information suggests that permitted discharges from oil and gas dril ling and other associated activiti es are unlikely to destroy or adversely modify habitats cri tical 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 li kely 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 li sted 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 lifespa n of a blue whale is estimated to be 80 years. The blue whale population is estimated be tween 1,300 and 2,000; there are currently no
estimates of the North Pacific stock of blue wh ale. 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. Th is in turn can cause entrapment by ice as the weather changes. Blue whales ar e usually found either in pairs (a s in mother and calf) or as a solitary animal. However, this species has b een 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 zooplankt on (euphausiids or krill). Since euphausiids are also the primary food for other whales in the Area of C overage, the blue whale is in direct competition with these species for food.ODCE for Arctic NPDES General Permit 1/24/06
4-40 4.7.4.3. Critical Areas or Habitats

Critical habitat has not been established for th is species within the Area of Coverage.

4.7.4.4. Effects Analysis

Endangered or threatened species may be a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in the di scharged 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 di scharge. Based on the limited areal extent of impacts in relation to the total area containi ng potential prey, the episodic nature of the discharges, the low concentrations of metals in the discharge, and the mo bility 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 r ecordings of drillship noise in the Area of Coverage oriented away from the noise source. Noise levels eliciti ng an avoidance response were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richa rdson et al., 1990, p. 156).

No specific habitats critical to the existen ce 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 criti cal habitats in the area proposed for exploratory oil and gas drilling, the potent ial for adverse impacts to habitat can not be determined definitively. However, it is unlikely that di scharges 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 Fi sheries as endangered under ESA throughout its range.ODCE for Arctic NPDES General Permit 1/24/06
4-41 4.7.5.1. Abundance and Distribution

Bowhead whales are distributed in seasonally ice- covered waters of the ar ctic and near-arctic, typically between 54° N and 75°N latitude in th e western Arctic Basin. The Bering Sea stock (also called the Western Arctic stock) is the la rgest remnant population and the only stock that is
found within U. S. waters. Prior to co mmercial fishing in the Bering Sea (mid-19 th century), it is estimated that the Western Arctic Stock population was between 10,400 and 23,000. The population dropped to less than 3,00 0 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 estimat ed population of 8,000 (Zeh et al. as cited in NOAA, 2002a). Acoustic data from 1993 has re sulted 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 migrat es annually from wintering areas (November to March) in the northern Bering Sea through the C hukchi Sea in the spring (March through June) and into the Canadian Beaufort Sea, where th ey 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 fu nneled between shore and the polar pack ice (Krogman as cited in NOAA, 2002a). Most of th e 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 southe rn 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 pa rt of the expanding Wester n Arctic stock. Fall surveys show that the bowhead whales are found close inshore east of Ba rter 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 othe r 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 b een defined in Alaskan waters; however, NOAA Fisheries is currently reviewing a petition to designate critical habitat. Bowheads are most sensitive during their spring mi gration when calves are present and their movements areODCE for Arctic NPDES General Permit 1/24/06
4-42 restricted to open leads in the ice. Feeding c oncentrations occur in ar eas east of Barter Island (MMS, 2003) and certain ar eas near Barrow are importa nt feeding grounds.

4.7.5.4. Effects Analysis

Endangered or threatened species may be a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in the di scharged muds.

The bowhead whales are seasonal feeders, obtai ning their food primarily on their summer range. The consumption of contaminated prey items coul d 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 containi ng potential prey, the episodic nature of the discharges, the low concentrations of metals in the discharge, and the mo bility 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 r ecordings of drillship noise in the Area of Coverage oriented away from the noise source. Noise levels eliciti ng an avoidance response were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richa rdson et al., 1990, p. 156).

No specific habitats critical to the existen ce 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 criti cal habitats in the area proposed for exploratory oil and gas drilling, the potent ial for adverse impacts to habitat can not be determined definitively. However, it is unlikely that di scharges from the limited exploratory activities proposed would adversely imp act 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.ODCE for Arctic NPDES General Permit 1/24/06
4-43 4.7.6.1. Abundance and Distribution

Fin whales range from subtropical (Hawaii and North American Paci fic coast) to arctic waters and are usually found in areas of dense producti vity. Their summer dist ribution extends from central Baja California into the C hukchi 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 fo r the Northeast Pacific fin whale stock are not currently available. The North Pacific fin wh ale population was estimated at 16,600 individuals in 1991 (MMS, 2002). Ranges of population estim ates 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, 2 003a). Fin whale abundance estimates for the Northeast Pacific stock from 1999 and 2000 surveys we re nearly five times higher in the centraleastern Bering Sea (est. pop. 3,368) than in the so utheastern Bering Sea (est. pop. 683) (Moore et al. as cited in NOAA, 2003a), a nd most sightings in th e central-eastern Beri ng Sea occurred in a zone of particularly high productivity along th e shelf break (Moore et al. as cited in NOAA, 2003a). Reliable information on trends in a bundance for the Northeast Pacific stock of fin whales is not currently available. There is no in dication 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 southw ard to California; however, a few animals may remain in the Navarin Basin (MMS, 2002). Fin whales usually br eed and calve in the warmer waters of their winter range. Breed ing can occur year-round, but the peak occurs between November and February (MMS, 2002).Nor thward migration begins in spring with migrating whales entering the Gulf of Alas ka from early April to June (MMS, 2002).

4.7.6.2. Diet

Fin whales are opportunistic feeders, taking euph ausiids, copepods, fishes, and squids. Since euphausiids are also the primary food for other whales in the Ar ea 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.ODCE for Arctic NPDES General Permit 1/24/06
4-44 4.7.6.4. Effects Analysis

Endangered or threatened species may be a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in the di scharged muds.

The fin whales are seasonal f eeders, obtaining their food primar ily 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 containi ng potential prey, the episodic nature of the discharges, the low concentrations of metals in the discharge, and the mo bility 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 r ecordings of drillship noise in the Area of Coverage oriented away from the noise source. Noise levels eliciti ng an avoidance response were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richa rdson et al., 1990, p. 156).

No specific habitats critical to the existen ce 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 criti cal habitats in the area proposed for exploratory oil and gas drilling, the potent ial for adverse impacts to habitat can not be determined definitively. However, it is unlikely that di scharges from the limited exploratory activities proposed would adversely imp act 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.ODCE for Arctic NPDES General Permit 1/24/06
4-45 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 Covera ge. 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 cen tral North Pacific stock is from the Hawaiian
Islands to northern British Columbia/South east 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 S ea and Aleutian Islands).

Prior to commercial whaling, the worldwide popu lation 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 a bundance for the central North Pacific stock is 4,005. The sum of the available estimates of th is stock for the known feeding areas is 2,036 (149 in Prince William Sound; 651 in Kodiak; 961 in Sout heast Alaska; and 275 in British Columbia). At least some portions of the stock have in creased in abundance betw een the early 1980s and 2000, although recent trends indicate that the st ock 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 feed ing 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 ar ound some oceanic islands. During winter (the breeding season), most humpbacks are found in temper ate 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 ta ke 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 la titudes. Summer ranges are often relatively close to shore including major coastal embayments and cha nnels. However, humpbacks may also summer offshore, as in the Gulf of Alaska.

4.7.7.2. Diet

The humpback whale diet consists of small sc hooling fishes (includi ng 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.ODCE for Arctic NPDES General Permit 1/24/06
4-46 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 a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in the di scharged muds.

The humpback whales are seasonal feeders, obt aining 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 re sulting in toxicity. The degree to which food supplies of these whal es 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 containi ng potential prey, the ep isodic nature of the discharges, the low concentrations of metals in the discharge, and the mo bility 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 r ecordings of drillship noise in the Area of Coverage oriented away from the noise source. Noise levels eliciti ng an avoidance response were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richa rdson et al., 1990, p. 156).

No specific habitats critical to the existen ce 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 criti cal habitats in the area proposed for exploratory oil and gas drilling, the potent ial for adverse impacts to habitat can not be determined definitively. However, it is unlikely that di scharges from the limited exploratory activities proposed would adversely imp act 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 whal e is listed by the NOAA Fisherie s as endangered under ESA throughout its range.ODCE for Arctic NPDES General Permit 1/24/06
4-47 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 so uth as 20°N (Roenbaum et al. as cited in NOAA, 2003b). Sightings have been reported as far south as central Baja Californi a in the eastern North Pacific and Hawaii in the central North Pacific, a nd 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 we re heavily exploited by commercial whalers,
concentrations were found in the Gulf of Alaska, eastern Aleutia n Islands, southcentral Bering Sea, Sea of Okhotsk, and Sea of Japan (Bra ham & Rice as cited in NOAA, 2003b). The preexploitation size of this stock exceeded 11,000 (NOAA, 2003b). In 197 3, 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 estim ate 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 temperat e 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 l east 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 incl uding copepods and small shrimp-like animals called euphausiids. Since euphausiids are also th e 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 th is species within the Area of Coverage.

4.7.8.4. Effects Analysis

Endangered or threatened species may be a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttingsODCE for Arctic NPDES General Permit 1/24/06
4-48 discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in the di scharged 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 containi ng potential prey, the episodic nature of the discharges, the low concentrations of metals in the discharge, and the mo bility 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 r ecordings of drillship noise in the Area of Coverage oriented away from the noise source. Noise levels eliciti ng an avoidance response were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richa rdson et al., 1990, p. 156).

No specific habitats critical to the existen ce 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 criti cal habitats in the area proposed for exploratory oil and gas drilling, the potent ial for adverse impacts to habitat can not be determined definitively. However, it is unlikely that di scharges from the limited exploratory activities proposed would adversely imp act 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 Fi sheries as endangered under ESA throughout its range.

4.7.9.1. Abundance and Distribution

The sperm whale is one of the most widely di stributed of any marine mammal species, although the shallow continental shelf apparently bars th eir movement into the north-eastern Bering Sea
and Arctic Ocean. Historic estimates for the ab undance 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 redu ced to 930,000 (Rice as cited in NOAA, 2003c).
The current and historic number of sperm whale occurring with in Alaska waters in unknown.

The seasonal movement of sperm wh ales in the North Pacific is unc lear at this time. Females and young sperm whales usually remain in tr opical and temperate waters year-round, whileODCE for Arctic NPDES General Permit 1/24/06
4-49 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); howev er, commercial whaling data revealed a great
deal of east-west movement between Alaska wate rs and the western North Pacific (Japan and the Bonin Islands), with little evidence of north-sou th 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 th is species within the Area of Coverage.

4.7.9.4. Effects Analysis

Endangered or threatened species may be a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in the di scharged muds.

The sperm whales are seasonal feeders, obtaining their food primarily on their summer range. The consumption of contaminated prey items coul d 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 containi ng potential prey, the episodic nature of the discharges, the low concentrations of metals in the discharge, and the mo bility 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 r ecordings of drillship noise in the Area of Coverage oriented away from the noise source. Noise levels eliciti ng an avoidance response were estimated to extend 4-11 km (2-6 nmi) from a drillship (Richa rdson et al., 1990, p. 156).

No specific habitats critical to the existen ce of the endangered whale species have been identified. Calving for the listed whales occurs outside the area under consideration in thisODCE for Arctic NPDES General Permit 1/24/06
4-50 document. Due to the absence of identified criti cal habitats in the area proposed for exploratory oil and gas drilling, the potent ial for adverse impacts to habitat can not be determined definitively. However, it is unlikely that di scharges 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 (Wes tern Alaska Stock)

The Western stock of Steller sea lion is list ed by the NOAA Fisheries as endangered under ESA throughout its range.

4.7.10.1. Abundance and Distribution

The Steller sea lion is distribu ted around the North Pacific Oc ean rim from northern Hokkaiddo, Japan through the Kuril Islands and Okhotsk Sea, Aleutian Is lands and central Bering Sea,
southern coast of Alaska and south to the Cha nnel 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 dec line continued for the western stock in Alaska. In 1998, surveys estimated a minimu m abundance of 38,788 Stelle r sea lions in the western U.S. stock (NOAA, 2002b). Counts at tr end sites during 2000 indicate that the number of sea lions in the Bering Sea/Aleutian Is lands 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 a nd various species of rock fish).ODCE for Arctic NPDES General Permit 1/24/06
4-51 4.7.10.3. Critical Areas or Habitats

The NOAA Fisheries has designate d critical habitat in Alaska for Stellar sea lions, which
includes all a number of r ookeries 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 a dversely impacted by exploratory oil and gas operations either directly, by the discharged muds and cuttings and other permitted discharges, or indirectly, via impacts to thei r habitat and food supply (e.g., bi oaccumulation of metals from discharge of muds and cuttings). The potential adverse effect s of drilling muds and cuttings discharges are of primary concern due to th e large volume discharged and the presence of potentially toxic components (e.g., metals) in the di scharged 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 Alas ka were conducted in the late 1970’s and early 1980’s. There is no disc ussion 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 in vestigation of chemicals associated with oil and gas exploration facilities in th e Arctic. Thus, the data reporte d for sediment concentrations represent estimates of the contaminant load; how ever, 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 th e 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 aqua tic fish and any fish da ta cannot be directlyODCE for Arctic NPDES General Permit 1/24/06
4-52 correlated with any sediment data collected in and near the vicinity of th e oil and gas exploration
facilities.

Other sources of constituents associated with oi l and gas exploration faci lities include sanitary and domestic wastes, desalination unit wastes, bo iler blowdown, test fluids, deck drainage, blowout preventer fluids, uncontaminated balla st 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 describe d in detail nor are they specif ic 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 othe r sources were not evaluated in this permit. Other exposures to stressful conditions may re nder species more or less sensitive to the constituents in the oil and gas e xploration 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 likeli hood 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 we ll as errors in chemi cal analytical methods.

When compiling concentration data the detec tion 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-det ects 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 base d 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 ar e those which were consid ered 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 effl uent discharge, but at concentrations that are well below the applicable water quality standards.ODCE for Arctic NPDES General Permit 1/24/06
4-53 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 respons e that is of intere st, using the species of interest and the experimental design most easily ex trapolated to the conditions of interest. However, there are no specific toxicity studies whic h are appropriate for this particular evaluation.

A thorough review of the scientif ic literature was conducted to identify as many sources of toxicity data for these parameters as possible. In some cases, t oxicity data were obtained from a previously compiled collection of toxicity in formation. 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 co ncentration for a parame ter did not report the endpoint [e.g., no observable e ffect concentration (NOEC), lowest observable effect concentration (LOEC)]. For these chemicals, th e lowest endpoint reported was used and then other endpoints were extrapolated us ing safety factors (e.g., if only a LC 50 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 si milar species, lifestage, or parameter increases the uncertainty associated with the evaluation, this approach is preferable to omitting the evaluation of a species or para meter with no toxicity data.

Actual direct testing of potent ial toxicity has not been conduc ted for all chemicals and listed species. While some toxicity data have been co llected for nearly all th e parameters of concern, toxicity data are generally not av ailable for every life stage of a listed species. In cases where little or no toxicity data are available for a para meter 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 clos est related organism for which information was available. In judging whether othe r (tested) species can be used as a surrogate for listed species, it is important to know whether th e tested species is more sensitiv e 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 sensitiveODCE for Arctic NPDES General Permit 1/24/06
4-54 species exposed to a certain con centration of a parameter would e xperience 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 specie s can be ascertained by comparing the toxicity observed in surrogate species to the toxicity observed in other sp ecies exposed to certain wellstudied chemicals. Dwyer et al. (1995) used th is 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 availabl e. 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 th e proposed permit, little or no toxicity data using aquatic species are available. Therefore, para meter-specific toxicity da ta cannot be used to assess potential effects to listed species. For so me species there is no data on specific chemicals nor are there data for extrapolation across chemi cals or species. For av ian species there are no
data in the literature for the e ffects of most chemicals. A de termination 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 contra ry a determination that there is a likelihood of
adverse effects will be made when there ar e 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 wa s simply based on the possibility of benthic organisms inhabiting the area adjacent to and w ithin the 1,000 meter area of the discharge.

Little information is presently available concer ning the effects of vari ous 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; Schulenberg er, 1970; Wilber, 1992). These studies indicate that the respons e to deposition and survival follo wing 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 le ss than 1 cm, benthos in the vicinity of the discharge receiving deposition in excess of this amount may be acutely impacted by drilling
activities.ODCE for Arctic NPDES General Permit 1/24/06
4-55 4.7.11.2.4. Exposure

Aquatic fish and mammal exposure to harmful s ubstances in this evaluation includes direct uptake or contact through absorption across the gills (for fish only) and in gestion of water, food,
or sediments. Direct contact for avian species is through inci dental ingestion of water and ingestion of food (prey species representative by salmonids).

Frequency and duration

In addition to the toxicity studies, the determina tion of an effect involv es some evaluation of exposure. The modeling used to estimate efflue nt 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 ex posure is adequate to address the habitat preferences of the endangered species.

Bioaccumulation

Ideally, to understand the relatio nship between the water column concentration and fish tissue, site-specific bioaccumulation factors (BAFs) ar e needed for each non-ionic organic compound of interest. BAFs account not only for uptake via wa ter exposure, but also uptake through the food
chain and the influence of sedime nt concentrations on both the food and water routes. Thus, sitespecific BAFs reflect the disequilibrium of th e 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 assu mptions in so doing. In general, one would prefer to develop and run a model for a specific lo cation that reflects back the state of the system (i.e., describing how each compound is partitioning into organic ma tter in the water column and sediments, and into lipids in the organisms of different trophic stat es, and how higher level organisms are obtaining their tissue concentr ations 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 explora tion facilities. The lack of es timating bioaccumulation for other organic chemicals results in an uncertainty in the effects for these chemicals. The resultant benchmarks may not be fully protecti ve of the endangered species.

Species Life history

While the life history of the species is discusse d in general terms there may be site specific
behavior or habitat factors which limit or alter the species preferen ces. A review of the scientificODCE for Arctic NPDES General Permit 1/24/06
4-56 literature found that younger life stages of fish ar e 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 potenti ally 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 Co mpany (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 b een 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 impairin g behavioral patterns such as breeding, feeding, or sheltering”, and “har ass” 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, feed ing or sheltering”. Further, the “incidental take” in Section 10(a)(1)(B) of the ESA mean s “any taking otherwise prohibited by Section 9(a)(1)(B) if such taking is inci dental 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 prohibiti on does not extend to proposed or candidate species.

Applying these definitions to the pr evious 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 mixi ng 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 de pendent 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 ei der species within the Ac tion 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 de ath to aquatic prey species. Another possible problem is the movement of the bowhead whale th at could result in multiple exposures to some
individuals.ODCE for Arctic NPDES General Permit 1/24/06
4-57 4.8. ESSENTIAL FISH HABITAT

Essential fish habitat (EFH) is the waters and su bstrate (sediments, etc.) necessary for fish to spawn, breed, feed, or grow to maturity. The Magnuson-Stevens Fish ery 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 an d/or quantity of) EFH.

In the Area of Coverage, EFH has been establis hed for red and blue king crabs, snow crabs, yellowfin sole, sculpins, and Pacific salmon (c hinook, 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 dept hs less than 100 fathoms (fm). Norton Sound has a discrete population of red king crab that is actively fish ed. 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 th e spring phytoplankton bloom in Southeast Alaska suggesting temporal sensitivity in the transition from benthic to planktonic habitat. Early juvenile stage red king crabs are so litary and need high relief habita t 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 ge nerally 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 S ound area reach 50% maturity at 6.8 cm and do not
attain maximum sizes found in other areas. Matu re 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, generall y in April. Natural mortality of adult red king crab is estimated at about 25 per cent per year due to old age, dis ease, 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 larv ae, and larger crabs, respectively. Adult kingODCE for Arctic NPDES General Permit 1/24/06
4-58 crab feed on mollusks, echinoderms, polycha etes, decapods, crustaceans, algae, urchins, hydroids and sea stars.

4.8.2. Blue King Crab

Blue king crab ( Paralithodes platypus ) has a discontinuous distri bution throughout their range (Hokkaido, Japan to Southeast Alaska). There are no distinct stocks of bl ue 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 s ponge, hydroid and barnacle assemb lages, 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 juve nile 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 relyin g on cryptic coloration for protection from predators.

Mature blue king crabs occur most often betw een 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 crab s have a biennial ovari an cycle and a 14 month embryonic period. Fecundity of females ra nge from 50,000-200,000 eggs per female. It is suggested that spawning may de pend on availability of nearshor e rocky-cobble substrate for protection of females. Larger older crabs di sperse farther offshore and are though to migrate inshore for molting and mating. Pacific c od is a predator on blue king crabs.

4.8.3. Snow Crab

Snow crabs ( Chonoecetes opilio ) are distributed on the continen tal shelf of the Bering Sea and Chukchi Sea. Snow crabs are thought to be of on e 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; howev er, the distribution of the population extends into Russian waters to an unknown degree. Only ma le crab greater than 7.8 cm carapace width may be harvested; however, a market minimum si ze 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 st ages settles onto bottom in nursery areas. Shallow water areas of the Ea stern Bering Sea are considered nursery areas for
snow crabs and are confined to the mid-shelf ar ea due to the thermal limits of early and late juvenile life stages. A geographic cline in size of snow crabs indi cates 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 cmODCE for Arctic NPDES General Permit 1/24/06
4-59 carapace width, respectively. While snow crab juveniles primarily feed on crustaceans, polychaetes, mollusks, diatoms, algae and hydroi ds; 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 m ean 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 clutch es can be fertilized from stored speratophores, but the frequency of this occurring in natu re is not known. Female s carry clutches of approximately 36,000 eggs and nurture the em bryos for approximately one year after fertilization. However, fecundity may decrea se up to 50 percent between the time of egg extrusion and hatching, presumably due to pr edation, parasitism, abrasion or decay of unfertilized eggs. Brooding probabl y occurs in depths greater th an 50 m. Changes in proportion of morphometrically mature crab s by carapace width have been re lated 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 th e 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 se als 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 Amer ican 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 a bout age six and they are fully se lected 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 estima ted 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 lifest yle and occupy separate winter spawning and summertime feeding distributions on the eastern Bering Sea shel f. From over-winter grounds near the shelf margins, adults begin a migration onto the inner shelf in April or early May eachODCE for Arctic NPDES General Permit 1/24/06
4-60 year for spawning and feeding. Adults feed mainly on bivalves, polychaetes, amphipods and echiurids. During wintertime migr ation 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 Pacifi c 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 s ubtidal 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 abou t 100 meter depth on the middle continental shelf (most are shallower than 50 m) th roughout the Bering Sea. Butterfly sculpins are distributed in the Bering Sea and Chukchi Sea in depths of 20-250 m. Bigmouth sculpi n 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 inte rtidal areas to depths of a bout 100 meters, but most common in shallow waters (<50 m). Scul pins are not a target of groundfis h 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 bycat ch 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 ro cky intertidal pools to muddy bottoms of the continental shelf, and rocky, uppe r slope areas. Most species live in shallow water or in tidepools, but some inhabit the deeper waters (to 1,000 m) of the contin ental shelf and slope. Most species do not attain a larg e 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 ar e 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 essent ial fish habitat in marine waters of Alaska formally is designated as the area within th e 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 th e outer boundary of the exclusive economic zone and to a depth of 500 m, while the written descri ptions of salmon indicate that in the juvenile marine stage, they (all five species) head to th e Bering Sea and south to the Gulf of Alaska for this stage (North Pacific Fisher ies Management Council, 1998).ODCE for Arctic NPDES General Permit 1/24/06
4-61 Habitat areas of particular concern (HAPC) incl ude nearshore areas of intertidal and submerged vegetations, rock, and other substrates. Shallo w nearshore estuarine and marine habitats including submerged aquatic vegeta tions and emergent vegetation ar e 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 communitie s or substrate with large participle size such as the Boulder Patch. St reams and lakes and other freshwater areas used by Pacific salmon and other anadromous fish (such as smelt), especially lo cated near urban areas
or areas with intensive human-induced develo pmental activities also are habitat areas of particular concern (North Pacific Fi sheries 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 cont ributions to healthy ecosystems. Since this federal action only occurs in marine waters, th is 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 St raight, 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 in fluenced by many factors, including general size and location of the spawning str eam, characteristics of adjacent shoreline and marine basin topography, extent of tidal fluctuations and a ssociated current pattern s, physiological and behavioral changes with growth, and different genetic characteris tics of individual stocks. When newly emerged pink salmon fry migrat e from freshwater to marine waters, they tend to remain along the shoreline for several w eeks 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 thei r 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 Ka raginskiy Gulf, 3.2 to 96.5 km from shore. Distributuion within these region s 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 obt ain large quantities of food suffi cient 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 an d generalized feeders and on occasion they specialize in specific prey items. Diel sampli ng 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 salm on fry and juveniles are food for a host of other
fishes and coastal seabirds.ODCE for Arctic NPDES General Permit 1/24/06
4-62 The population biology of pink salmon revolves ar ound a two-year life cycle. Entering the estuary as a fry at around 3 cm in length, maturi ng 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 environm ent, subadult and pink salmon are known to be eaten by fifteen different marine mammals, shar ks, other fishes (e.g., Pacific halibut), and humpback whales. Because pink salmon are the most abundant salm on, it is likely they comprise a significant portion of th e salmonids eaten by marine mammals.

4.8.6.2. Chum Salmon

Chum salmon ( Oncorhynchus keta ) are widely distributed thro ughout the Bering Sea, Arctic Ocean, Chukchi Sea, and Beaufort Sea to the Mackenzie River delt a. 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 fish eries 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 Fe bruary 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, estu aries 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 Fa lse 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 st art maturing and begin their migration to their spawning streams. In Alaska, chum salmon retu rn from the ocean to spawn between June and
November. Juvenile chum salmon utilize a wi de variety of food items, including mostly invertebrates (including inse cts), 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 domina te the northern stocks. Recently, immature and maturing chum salmon from Washington, British Co lumbia, 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 essen tial in their life history that make them very vulnerable: (1) reliance on upw elling ground water for spawning a nd incubation, and (2) reliance on estuaries/tidal wetlands for juvenile rearing af ter migrating out of freshwater streams.

The 1976-77 Regime Shift in the North Pacific O cean 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. Ho wever, as the abundance increased age at maturity increased and the size at age decreased dr astically. Chum salmon of the same age in theODCE for Arctic NPDES General Permit 1/24/06
4-63 early 1990s weighed up to 46 percen t less than they weighed in th e early 1970s. These changes in size and age at maturity as population number s 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 oc ean 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 m onths 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 resi de in the estuarine or nearshore environment before moving into oceanic waters. They are typi cally distributed in offshore waters by autumn following outmigration. During the initial mari ne period, yearling sockeye forage actively on a variety of organisms, apparently preferring copepods and insects, bu t 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 leng th 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. Measur ed 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 fi rst few months, and is probably influenced by
three factors of unknown relative im portance: (1) size and age at seaward migration; (2) timing of entry into the marine environment; and (3) le ngth of stay in the ocean. Variations in oceanographic conditions and in marine pred ator 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 poor ly 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 largestODCE for Arctic NPDES General Permit 1/24/06
4-64 river systems (e.g., Yukon River) tend to support th e largest aggregate runs of chinook salmon and have the largest individual spawning populations.

Chinook salmon are highly prized by commercial, s port, and subsistence fishers because of their large size and excellent palatability. In Al aska, approximately 1 million chinook salmon are harvested annually. Because of their distributi on in the water column, the majority of the
chinook salmon harvested in commercial troll fisher ies 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, ther e 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 effo rt 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 mi gration 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 fi sh. Stream-type fish have long freshwater residence as juveniles (1-2 years), migrate rapi dly 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 freshw ater 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 por tions of the watershed. Within these two types, there is also substantial variability due to a combination of ph enotypic plasticity and genetic selection to local conditions. For example, adult run-timing is st rongly 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 year s, the term ‘juvenile ’ is better defined by physiological progress of maturati on 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 y earling 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 hist ory predominates although ocean-t ype 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. Bo th stream- and ocean-type fish utilize a wide variety of habitats. The seaward migration of smo lts is timed so that the smolts arrive in the estuary when food is plentiful. Migration and re aring habitats overlap. Stream flows during the migratory period tend to be high, which facili tates seaward movement and provides some sheltering from predation. After entering saltw ater, chinook juveniles disperse to oceanic feeding areas. Ocean-type fish have more extend ed 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 geographicODCE for Arctic NPDES General Permit 1/24/06
4-65 range, encompassing different ecotypes and very diverse habitats. Ocea n distribution patterns have been shown to be influenced by both ge netics and environmental factors. Migratory patterns in the ocean may have evolved as a bala nce 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 sp ecific characteristics. These local adaptations
result in different and diverse characteristic s of biological importanc e, 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 th e estuarine and marine habitats beyond presence/absen ce 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 di et of other fishes, marine mammals, and coastal sea birds. Chinook salmon are the most piscivor ous 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 Al aska, 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 histori cally 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 coas tal marine migration corridors, near the mouths of rivers and streams, and in freshwater migration areas. T hose fisheries coincide with migrations toward spawning areas from July through October.

In fall, juveniles may migrate from summer reari ng areas to areas with wi nter habitat. Such juvenile migrations may be extensive within th e natal stream basin or between basins through salt water or connecting estuaries. Seaward migr ation of coho smolts occurs usually after 1-2 years in fresh water. The migration is tim ed 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 rout es. Alaska coho genera lly migrate north and offshore into the Bering Sea. Unobstructed pa ssage 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. In tertidal 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 juve nile production in small streams. Growth in these areas is particularly rapid because of a bundant invertebrate food. Habitats used include glides and pools during low tide, and coho occupy the freshwater lens during high tide. In fall, juvenile cohoODCE for Arctic NPDES General Permit 1/24/06
4-66 move upstream to overwinter in freshwater. Af ter leaving freshwater, coho spend up to four months in coastal waters before migrating offs hore and dispersing thro ughout 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 b een noted at this stage. Mari ne 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, cutth roat 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 befo re 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 th e 12 to 14 month after l eaving coastal areas.
Some coho also use coastal and inshor e waters at this life stage, but those are likely to be smaller at maturity. The spacial dist ribution of suitable habitat cond itions is affected by annual and seasonal changes in oceanographic conditions; howeve r, 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 ha locline which may range from 100 to 200 m in depth. Coho growth is best in epipelagic o ffshore habitat where fora ge 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 ma rine waters. NPDES permits are established to protect water quality in accordance with State water quality standards. The standards are developed to protect th e designated uses of the wa terbody, 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 requirement s (refer to Section II and Appendix A and B of the fact sheet for specifi cs pertaining to the proposed permit) for an NPDES discharger are in accordance with stat e water quality standards using procedures prescribed in EPA guidance (USEPA, 1991).ODCE for Arctic NPDES General Permit 1/24/06
4-67 • The majority of activity under this permit will occur in the Beaufort Sea; it is unlikely that activity will occur in the Chukchi S ea, Hope Basin or Norton Basin (MMS, 2002). Generally, there is little evidence of viab le self-sustaining sa lmon 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 drilli ng cuttings may impact minor prey, benthic organisms (at sublethal levels), and benthic ha bitat, 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), a nd the recovery period of impacted benthos is estimated to be less than two years.

• While no specific demersal fish spawning locati ons have been identified in any of the Arctic areas of coverage, a number of esse ntial 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 ar ea coincides with th e period of egg produc tion. 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 smot her demersal fish eggs is probably the most serious potential impact of expl oratory 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 explorati on activities in the broader sense of the impact
on the environment which results from the incremen tal impact of the action when added to the other past, present, and reasonabl y foreseeable future actions ofall activities (federal and nonfederal).

Impacts of any kind from a single drilling site are likely to be loca lized. Although benthic organisms may be smothered or develop body burdens of heavy metals above background in localized areas, the benthic and epontic (ice-a ssociated) 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 commun ities 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 change s in community structure could be cumulative spatially and over the short term, but it is unlikel y 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 th e magnitude and signi ficance of cumulativeODCE for Arctic NPDES General Permit 1/24/06
4-68 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 im pacts from drilling discharges is the susceptibility of the area to periodic stor m surges. These events could, by redistributing localized platform discharges, conseque ntly redistribute the zone of impact.

4.10. CONSERVATION MEASURES

The general permit has several conservation measur es 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 ba rrier islands) and the 5-m isobath;

• Within 1000 m of the Steffansson Sound B oulder Patch (near the mouth of the Sagavanirktok River) or between individua l units of the Boulder Patch where the separation between units is greate r 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 fr om 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-wate r conditions or within 1000 m of river
mouths or deltas.

• The permittee is prohibited from discharg ing 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 drilli ng fluids and cuttings, and the permittee conducts the environmental monitori ng 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 possibl e, areas of sea ice cracking or major stress fracturing unless authorized otherwise from the EPA.ODCE for Arctic NPDES General Permit 1/24/06
4-69 4.10.3. Environmental Monitoring Requirements

The permittee is required to conduct the environm ental monitoring requirements of this section
when the authorization to disc harge 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 notic e of intent (NOI) (i.e., the application for coverage under the general permit). The permitt ee must incorporate any changes required by the EPA or ADEC in the monitoring program’s design. A copy of the final st udy plan must be sent to the North Slope Borough. The permittee must include in the environmental monitoring study plan relevant hydrographic, sediment hydroc arbon, and heavy metal data from surveys conducted before and during drilli ng fluid disposal operations and up to at least one year after drilling operations cease. The permittee must s ubmit 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 monito ring 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 fro m 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 A ppendix 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 prot ect the species as a whole. These species are currently the best available surrogates for asse ssing 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 PlanODCE for Arctic NPDES General Permit 1/24/06
4-70 The permit requires the development and implemen tation of a Quality Assurance Plan (QAP) to assist in planning for the collect ion 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 secti on IV.A of the permit lo cated 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 rele ase of pollutants from industrial facilities to waters of the U.S. The permit requires the permittee to prep are 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 Ma nagement Practices Plan. The drilling fluid plan requiremen t is also based upon the Polluti on Prevention Act (PPA) and its policy of prevention, reduction, r ecycling, and treatment or wast es (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 th e information needed and the methods required to formulate the mud/additive syst ems in order to meet the effluent toxicity limit. The intent of the mud plan is a writte n guide to planning for and using a mud/additive system in compliance with the permit. To da te, 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 t oxic than the required
limitation.

The mud plan is intended to demonstrate that th e 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 disc harge 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 clearl y stated procedure for deal ing with situations in which additives not originally planned for are need ed 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 si gnificant effect upon the discharge toxicity. Criteria for reaching this type of last minute additive decision are required to be clearly specifiedODCE for Arctic NPDES General Permit 1/24/06
4-71 in the drilling fluid plan. See section IV.C of the pe rmit located in Appendix C for more details regarding the drilling fl uid plan requirements.ODCE for Arctic NPDES General Permit 1/24/06
5-1 

## 5.0 HUMAN HEALTH

This section provides a discussion of the imp act to human health exposure of discharges associated with oil and gas exploration activitie s within the Beaufort Sea, Chukchi Sea, Hope Basin, Norton Basin, and adjacent state waters. Sin ce it is most likely that exploration activities will occur in the Beaufort Sea area, this evaluati on mainly takes into account exposures in that are likely to occur in th at 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 informa tion suggests that effects of discharges are more likely to occur there. This area generally incl udes nursery areas since la rval 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 si gnificant concentrations of heavy metals from drilling fluids and cuttings is the potential pr incipal 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 mamm als if eaten in sufficiently large amounts, but neither the Food and Drug Admini stration (FDA) nor the USEPA has set maximum levels of
these chemicals in fish and sh ellfish slated for human consum ption, with the exception of methylmercury. This evaluation only consider s the potential effects to humans from consumption of aquatic life likel y to be exposed to discharges from oil and gas exploration facilities authorized by this permit.

The Area of Coverage is characterized by a f ood 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-r ound, with different species bei ng 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. Ther efore, the annual harvestODCE for Arctic NPDES General Permit 1/24/06
5-2 and consumption of species closely reflects the timing and specific mix of locally available resources that varies by region (Beaufort Sea, Chukchi Sea, Hope Basi n, or Norton Basin) and local communities within the Area of Coverage. Si nce the pattern of resource availability is so
unstable and the harvest success for individual fam ilies and villages is so variable, communities in Arctic Alaska have adapted to form a hi ghly complex, diverse, and flexible pattern of subsistence activity that continually adapts to harvest opportunities. Exte nsive sharing and trade of subsistence harvests among families and between villages further complicates the subsistence consumption patterns.

A description of subsistence-harv est 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 dr illing discharges in the Beaufort Sea.

A description of subsistence-ha rvest patterns for each community and potential areas impacted by exploratory drilling in the Chukchi Sea is pr ovided in MMS (1991). The subsistence areas and activities of Wainwright, Barrow, Atqasuk, Nu iqsut, Point Lay and Point Hope are expected to be affected, at least indirectly, by drilling disc harges in the Chukchi Sea. Point Lay and Point Hope communities rely extensiv ely on resources harvested within or adjacent to the Chukchi
Sea.

A description of subsistence-ha rvest 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 th e Alaska Native Tribes’ subsistence harvest; 50- 75% of Norton Sound Village diet is by acquis ition of marine resources (MMS, 1982). The subsistence areas of Kingikmiut, Kauwarak, Un aligmiut, and Ikogmiut are expected to be affected, at least indirectly, by drilling discharges in the No rton Basin. These include the contemporary communities of Shishmaref, Brevig Mission, Teller, Mary’s Igloo, Whales, Inalik (Little Diomede), King Island, Gambell, Savoong a (St. Lawrence Island), Solomon, Golovin, White Mountain, Council, Elim, Koyuk, Shaktool ik, Unalakleet, St. Mi chel, Stebbins, Kotlik, Bill Moore’s Slough, Hamilton, Emmonak, Alakanuk, and Sheldon Point.

A description of subsistence-ha rvest patterns for each community and potential areas impacted in the Hope Basin is provided in USEPA (1984). Th e subsistence areas and activities of Kivalina, Naotak are expected to be affected, at least indi rectly, by drilling discharges in the Hope Basin. The communities of Kotzebue, Ambler, Buck land, 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 subs istence communities. The relative importance of
fisheries to the annual subsistence harvest varies between communities depending on theODCE for Arctic NPDES General Permit 1/24/06
5-3 availability of other food res ources. Harvested species depe nd 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 includ e chum and pink salmon, char cod, smelt, burbot, Arctic char, arctic cisco, least cisco, grayling, capelin, sculpin a nd 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 incl ude 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 consum ption, 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 availabl e 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 scul pin. The consumption of all fish species for individual communities is not known; salmon co mprise 30-40% of Norton Sound Village diet.

Harvested species in the Hope Basin are Arc tic char, chum salmon, sheefish, whitefish, tomcod, and smelt. Fishes comprise 38.3% of the Kiva lina subsistence resources harvested and 45.6% of the Naotak subsistence resources harvested (U SEPA, 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 proportio n of the edible reso urces harvested by subsistence communities. The native populations are opportunistic hunters. This tendency, along with natural variability in mammal abunda nces, leads to variabil ity 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 importa nce to subsistence harvests are the bowhead and beluga whales; bearded, ringed, ha ir and spotted seals; walrus; and polar bear. Bowheads are unavailable to the people of Point Lay (MMS, 1 991) 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 im portant 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 an imals have been taken annually by residents of the Chukchi and Bering Seas (USFWS, 1993).ODCE for Arctic NPDES General Permit 1/24/06
5-4 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 cons umption 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 s ea lions. Marine mammals comprise 15-20% of the Norton Sound Village diet (MMS, 1982).

Harvested species in the Hope Basin bearded, sp otted, and ringed seals; and beluga and bowhead whales. Marine mammals comprise 42.3% of the Kivalina subsistence harv est 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 av ailable. Birds are particularly important to the whaling camps even though they are harvested inci dentally to other subsistence activities. Migratory waterfowl and their eggs are an impor tant source of food fo r 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 consum ption 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 co nsumption data is not available for these
communities.

5.2.2. Effects Analysis

Some impacts may be measurable, but their e ffects may be minimal and/or short-term in duration; therefore, they may not require avoi dance or mitigation. Adverse impacts that areODCE for Arctic NPDES General Permit 1/24/06
5-5 reduced by mitigation below the “significance thres holds” that are incorporated into the permit, or that are demonstrated to be acceptable becaus e the risk of the impact occurring is small, are considered “nonsignificant.” For this evaluation, “signifi cance threshold” is defined as the level of effect that equals or exceeds the adverse chan ges 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 ev aluating the effects of drilling discharges. Exploratory operations with in nearshore waters ha ve a higher likelihood of adverse impacts to fisheries, a lthough overall the impact is exp ected to be minimal. Mammal subsistence harvesting may be affected to the exte nt that discharge sites may alter the distribution of the animals; however, effects should be insigni ficant if discharge loca tions are not in close proximity to each other. The likelihood of signifi cant 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 sp ecies. 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 ex ploratory phase in the Ar ctic lease sales. The hazard associated with consuming fish and shel lfish contaminated with metals or petroleum hydrocarbons is expected to be low. The reas ons for this assessment are: bioconcentration factors for heavy metals other than methylmerc ury 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 disc harges are too small to contribute substantially to the diet of fish or shellfish harvested by fisheries.

The Norton Sound environment is cu rrently in a pristine state w ith no major industry and a local population of only 12,000 (OCSEAP as cited in MMS, 1982). Disruptio n of the natural environment may have sociological as well as environmental impacts; the natives of this area depend on the migrating mammals, native fisher ies, and seasonal bird populations for a subsistence harvest. Some of the potential impa cts from offshore oil and gas discharges include
adverse effects to the benthic bi ota from platform discharges, possible disruption of migratory patterns of marine mammals, a nd interference with the subsistence harvest of the natives.ODCE for Arctic NPDES General Permit 1/24/06
5-6 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
6-1 

## 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 tr ading; 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 vi ew of the world centered on the traditional hunting, fishing, and gathering way of life associat ed with local resources. The collection, processing, and
distribution of subsistence reso urces 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 occu r in their society. The contin ued opportunity to engage in subsistence uses is a fundamental component of all Alaska Native cultures and serves as the keystone to social, ethn ic and psychological identity. Theref ore, the loss of any subsistence resource could greatly impact the so cial 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 el aborate food distribution system and has enormous cultural significance for all communities. Bowhead whaling also remains at the center of Inupiat spiritual and em otional life; it embodies the values of sharing, association, leadership, kinship, ar ctic survival, and hunting prowe ss. Because they migrate too far from shore, bowheads are unavailable to th e people of Point Lay (MMS, 1991). In Point Lay, a communal hunt of the beluga whale serves ma ny 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 cultura lly 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 providi ng 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 c onstruct temporary shelters and traditional boats. Seal skins and gut are used for clothing and other mohme uses, as well as crafts. Seal skin, particularly th at of the bearded seal, is also us ed 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 intoODCE for Arctic NPDES General Permit 1/24/06
6-2 functional items such as knife or ulu handles a nd needle cases. Walrus cowhides are the only suitable hide for covering the skinboat (umiak) a nd 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. Pola r bear and seal fur are used to make parkas, slippers, mukluks, hats, dolls, and Eskimo yo-yos. Bird beaks, bones, and feathers ador n 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 explorati on discharges have the potential to cause a voidance behavior or loss of supporting habitat for tribal resources in the marine envir onment. This would result in the potential reduction in local fish and marine mammal populati ons, increased travel distance and hunting time required to harvest resources, pote ntial reductions in harv est success rates, and increased competition for nearby subsistence resources. The following examples illustrate the sensitivity of Arctic communities to Western in fluence: The community of Teller has already shown decreased subsistence dependence and pe rhaps loss of subsistence knowledge due to a long history of contact with other commercial ac tivities (e.g., mining, rei ndeer 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, them selves, are likely to have far more adverse impacts to tribal resources than the discharges as sociated with those activities.ODCE for Arctic NPDES General Permit 1/24/06
7-1 

## 7.0 RECREATIONAL AND COMMERCIAL FISHERIES

This section describes the recreational and commerc ial fisheries in the Area of Coverage and the potential impacts exploratory drilling discharges may have on these activities. Two major
determinations of whether a fisher y is viable are the abundance and bi omass of the target species. Fish biomass and diversity in both the Beaufort and Chukchi Seas are relatively low. The abundance and biomass for epibenthic invertebrate s 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 info rmation on commercial harvests is provided in
Section 4.8.

No commercial fishery is currently operating wi thin the boundaries of the Beaufort Sea. The only continuous commercial fi shery operations on the Alaska North Slope occur during the
summer and fall months in the Colville River De lta, adjacent to the Beaufort Sea Area of Coverage (MMS, 2002). The Colville River delta fi sheries include two comm ercial enterprises. Arctic cisco is the most impor tant 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 cisc o varies considerably fr om year-to-year due to variability in juvenile recruitm ent, and unpredictable physical fact ors such as the distribution of saline water in the delta (Moulton et al., 1992).

Aside from a relatively small chum salmon fish ery 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 commer cially 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 fisherie s 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 commerci al 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 oppor tunities in the Area of Co verage are somewhat limited compared to other areas of the state due to the restricted and costly a ccess, the lack of supportODCE for Arctic NPDES General Permit 1/24/06
7-2 facilities, and the harsh weathe r conditions. Non-resident part icipation is often limited to professionally-guided fishing trips fo r Arctic char, grayling, and salmon.

7.3. EFFECTS OF DRILLING DISCH ARGES ON HARVEST QUANTITY

Disposal of drilling muds via any discharge technique is not expect ed to directly interfere with
commercial fish harvests.

7.4. EFFECTS OF DRILLING DISCH ARGES ON HARVEST QUALITY

The exploratory drilling discharges are not expected to significan tly impact the quality of the
commercial fish harvest.

7.5. SUMMARY

Nearshore locations used for commercial fisher ies are predominantly out side areas that could conceivably be impacted by activities conduc ted during Beaufort Sea and Chukchi Sea exploratory drilling discharges. Exploratory discharges within state waters have a higher likelihood of adverse impacts to fish eries, although overall the impact is expected to be minimal.ODCE for Arctic NPDES General Permit 1/24/06
8-1 

## 8.0 COASTAL ZONE MANAGEMENT

8.1. REQUIREMENTS OF COASTAL ZONE MANAGEMENT ACT

The Coastal Zone Management Act requires that st ates 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) (1 6 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 ha s the responsibility to either concur with or object to the consistency dete rmination. 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 incl ude the following information (15 CFR 930.58):

• A detailed description of the proposed activity and its asso ciated facilities;

• A brief assessment relating the probable coas tal zone effects of the proposal and its associated facilities to relevant elements of the CZMP;

• A brief set of findings indicating that the pr oposed activity, its associ ated facilities, and
their effects are consistent with re levant provisions of the CZMP; and

• Any other information required by the state.

Consistency determinations are required if a fede rally licensed or permitted activity “affects” the coastal zone. Discharges of dr illing muds and cuttings during exploration oil and gas activities in the Area of Coverage are expected to o ccur in the adjacent state waters, therefore, a consistency assessment is required. The enclos ed certification statement is based upon the requirements listed in 15 CFR Part 930.39 a nd the Alaska Division of Governmental Coordination's "Guide to Preparing an AC MP 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.govODCE for Arctic NPDES General Permit 1/24/06
8-2 8.3. PROJECT INFORMATION

The proposed reassurance of the Arctic Gene ral 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 Chukc hi 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 m ud 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; un contaminated bilge water; excess cement slurry; mud, cuttings, and cement at the seafloor; and test fluids. A ma p 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 con tinue 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 we lls (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 practic es 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 admini stratively extended beyond the five year term for covered facilities that timely r eapply until EPA reissues the GP.

8.4.3. Site Plan

An applicant is required to submit a map of the c overage area with the No tice of Intent to be
authorized under this GP if they are requesting a mob ile discharge authorization.ODCE for Arctic NPDES General Permit 1/24/06
8-3 8.4.4. Supporting Documentation

Please refer to the proposed GP in Appendix C, F act 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 implemen t 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 Mana gement Service planning areas. The proposed GP would authorize qualifying discharges into wate rs of the U.S. located in the coverage area.

8.6. CONSISTENCY WITH THE ENFORCEAB LE 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 pr oposed 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, Al aska 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.ODCE for Arctic NPDES General Permit 1/24/06
8-4 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 th e local, state and federal laws applicable to the coverage area.

6 AAC 80.130: Habitats

POTENTIAL IMPACTS

The problems that are anticipated to arise s hould 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 wh ich 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 lim itations restricting the discharge of pollutants. Pleas e 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 prov isions 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 eff ects from activities authorized by the GP.

OFFSHORE AREAS

The proposed GP would authorize the discha rge of domestic wast ewater, construction dewatering, discharges of hydrosta tic test waters, storm water and discharges from mobile response units to the marine environment. Th e GP contains proposed effluent limitations for each category of discharger and requires that a BMP Plan be develope d, as described above.

WETLANDS

Discharges of wastewaters to tundra wetlands are not author ized under this proposed GP.

RIVERS, STREAMS, AND LAKES

Discharges of wastewaters to rivers, streams a nd lakes are not authorized by this proposed GP.ODCE for Arctic NPDES General Permit 1/24/06
8-5 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 w ith technology-based effluent lim itations or any more stringent limitation necessary to achieve state water quality st andards. Section 402 of the Act authorizes EPA to issue NPDES permits with conditions necessa ry to ensure that a discharge complies with the requirements of the CWA.

The proposed GP would include e ffluent limitations, best manage ment practices, and monitoring and reporting requirements to ensure that authorized discharges comply with the Alaska Water Quality Standards (AWQS).

Effluent Limitations. The pr oposed effluent limitations in corporate speci fic AWQS for parameters applicable to each category of discharg e. It is anticipated that the ADEC will certify mixing zone provisions into the GP. If this doe s not occur, no mixing zone provisions for the proposed discharge will appear in the final GP.

Best Management Practices. Pa rt IV.B of the GP includes a requirement to develop and implement a BMP Plan in order to ensure complia nce with the AWQS for discharges authorized under this permit.

Monitoring and Reporting Requirements. The GP requires monitoring fo r 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 upla nd activities which do not involve a discharge
to the waters of the United States.

6 AAC 80.150: Historical, Prehistori c, and Archeological Resources

It is unlikely that discharges au thorized under this GP would aff ect historical, pr ehistoric, and archaeological resources. However, the discharge of dredged or fill material associated with the construction of the facilities may affect these res ources. The state would have an opportunity to identify these resources duri ng the ACMP review for the required Section 404 permit.ODCE for Arctic NPDES General Permit 1/24/06
8-6 8.7. CONSISTENCY DETERMINATION

15 CFR Part 930.37. Consistency Determin ations for Proposed Activities

Based on the above analysis of the state and di strict 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 Chuckc hi 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 w ith, the ACMP, including affected coastal district

programs.ODCE for Arctic NPDES General Permit 1/24/06
9-1 

## 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 crite ria at the edge of any author ized mixing zone for drilling muds and cuttings under this permit is assessed in this section.

Marine water quality criteria fo r 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 st ated for protection of humans due to consumption of marine fish (CMF) (assuming a 10 -6 risk level and an averag e lifetime consumption of 6.5 grams per day (g/day) of contaminated fish a nd/or shellfish for a 70 kg male) (USEPA, 1986).
The chronic and CMF criteria ar e applicable to relatively con tinuous discharges that expose organisms in their vicinity to a relatively constant flux of polluta nts. Acute criteria values are applicable to instantaneous releases or short-term disc harges of pollutants.

9.1. TRACE METALS

The four methods of sample prep aration for metals analysis th at have been recognized by EPA include 1) total metals, 2) total recoverable me tals, 3) acid soluble metals, and 4) dissolved
metals. The first three of these methods measure metals that are dissolve d in water, along with metals that become dissolved when samples are re fluxed 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 μ m poresize filter at the ti me of collection.

Historically, federally recommended water quality cr iteria 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 protec t aquatic life (USEPA, 2002). This guidance supersedes past criteria document statements expr essing criteria in terms of the dissolved metal. The new EPA guidance (USEPA, 20 02) recommends using dissolved metals because they more accurately reflect the bioavailable fraction, and hence the potential t oxicity of a metal. The state of Alaska has adopted these crite ria for protection of state wate rs in Title 18, Chapter 70 of the Alaska Administrative Code (18 AAC 70). EPA also uses these criteria to ensure protection of
federal waters.ODCE for Arctic NPDES General Permit 1/24/06
9-2 9.1.1. Drilling Fluids

Evaluation of water quality compliance for the di scharge of drilling muds during exploratory oil and gas drilling in previous ODCEs has relied on measurements of me tals concentrations performed on generic drilling muds. Metal c oncentrations were reported as “whole mud concentrations,” which were assumed to be equiva lent to values obtained using the total metals
method. Previous ODCEs have also assessed co mpliance 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. T oxicity from dissolved metals are thought to be of primary concern, as organisms are exposed to di ssolved 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 us ed 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 m uds are similar to that measured for dredged
material. Previous ODCEs have also used a ratio of 0.001 as a conser vative estimate of the partitioning between dissolved and solid phases fo r all metals when evaluating compliance with water quality criteria. However, Avanti Corpor ation (1993) provided measured trace metal leach percentages from barite and drilling fluids, whic h 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) reporte d 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 dr illing fluids have the potential to be problematic (Case Study I). Then the maxi mum and mean leach factors in Table 9-1 were
used to convert the total metals concentra tions in the drilling fluid to water column concentrations (Case Studies II and III, resp ectively). 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 fo r each discharge scenario (e.g ., open-water discharge in 20-m water depth) available in Tables 3-5 and 3-7. The predicted disso lved metal concentration were compared directly to the marine water quality crit eria, 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 qualit y criteria at the edge of the mixing zone).ODCE for Arctic NPDES General Permit 1/24/06
9-3 (It should be noted that for chromium, the tota l chromium concentration in the mud was assumed
to be chromium VI since this is the Alaska wa ter quality criteria but there is no data for the chromium VI concentration in drilling. This w ould provide an overestimat e of the chromium VI
concentration in the water column due to the dril ling fluid.) However, Ca se Studies II and III
show that all dissolved metal concentrations are le ss 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 crite ria for any metals based on the predicted dilutions obtained from the OOC model runs. However, more info rmation should be obtained to show partitioning of metals from the discharg e 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 partiti oning of metals between dissolved and particulate phase s of drilling muds and cutti ngs, 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. Dre dged materials are naturally occurring sediments frequently containing elevated concentrations of contaminants, with variab le 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 material s 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 we re evaluated under three case analyses: (1) that the all the metals in the drilled cuttings will disso lve in the water column; (2) that the dissolved metals fraction is two orders of magnitude lower th an 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, th is 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 or ders of magnitude higher than t hose 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 ba sed on the physical similarity of drilled cuttings and dredged materials.

Tables 9-6 through 9-8 show the maximum pred icted dissolved metal (arsenic, cadmium, chromium, copper, lead, mercury, and zinc) concen trations for each case study at the edge of a 100-m mixing zone due to the discharge of Alas kan 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 pred icted by the OOC model for eachODCE for Arctic NPDES General Permit 1/24/06
9-4 discharge scenario (e.g., open-wate r discharge in 20-m water depth) available in Tables 3-5 and 3-7. In general, the calculat ion was performed as follows:

[Dissolved Metal] MZ = [(Total Metal) EOP (Partition Coefficient)]/ [Dilution Factor] (1)

where: [Dissolved Metal] MZ = the dissolved metal concentr ation at the edge of the mixing zone in mg/L.

[Total Metal] EOP = the drilling mud total metal c oncentration 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 diluti on 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 thes e 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, ex cept for lead and zinc in Case II (Table 9-7) for open water discharges at a dept h 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 obtai ned from the OOC model runs. However, more information should be obtained to show partiti oning 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 al so 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 o ils, respectively. None of the individual compounds that were de tected have established marine water quality cr iteria. More organic chemical data are needed to fully assess the potential fo r organic compounds in discharged drilling muds to vi olate water quality criteria.ODCE for Arctic NPDES General Permit 1/24/06
9-5 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 exceedan ces under certain circumstances. The NPDES permit limits are 1.0 mg/L as a maximum daily li mit within Alaska State waters with an approved mixing zone and in Federal waters. EP A 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 mi xing 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. Howe ver, more information (e.g., model verification, environmental sampling, effluent sampling) sh ould be obtained to determine whether the assumed dilution factors are appropriate for future analysis.

9.4. SUMMARY

Trace metals in drilling mud discha rges 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 en vironment is needed to provide a more complete analysis. An assessment of the potential for or ganic 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 crit eria for some of the chemicals detected in the muds. Total residual chlorine in sanitary disc harges is not expected to exceed marine water quality criteria; however, the dilution factors a nd modeling should be veri fied to ensure that water quality standards are met in future analysis.ODCE for Arctic NPDES General Permit 1/24/06
9-6 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
10-1 

## 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 indi cates 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 th is chapter is to briefly summarize information pertinent to the determination of unreasonable degradation.

While the information contained in this ODC E is intended to provide the basis for the determination of unreasonable degradation, it shoul d 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 c overage. Of particular concer n 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 res earch be conducted to accomplish the following:

• Develop more laboratory data on subletha l 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 environmen tal concentrations of drilling fluids (e.g., Parrish and Duke 1990).

• Determine total recoverable metal concentr ations 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 deme rsal 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 explora tion wells and 12 delineation wells wi ll be drilled in the Beaufort Sea, 2 exploration wells and 2 delineation wells w ill be drilling in the Chukchi Sea, and no wells will be drilled in the Hope Basin or Norton S ound. Drilling fluids a nd cuttings will be theODCE for Arctic NPDES General Permit 1/24/06
10-2 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 dril ling mud systems. Mass loadings of the additives depend on the concentrations, frequency of usage, and condition s encountered during drilling. It is estimated that 10,345 bbl drilling muds a nd 58,040 bbl drill cuttings (8, 085 bbl drilling muds and 50,160 bbl drill cuttings in the Beaufo rt Sea; 2,260 bbl drilling muds a nd 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 disc harge 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 dril ling 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 s upport activities (i.e., sanitary and domestic wastes, deck drainage, blowout preven ter fluid, desalination unit waste, fire control system test water, non-contact c ooling water, ballast water, bilg e water, boiler blowdown, test fluids, excess cement slurry, and mud, cuttings, ceme nt at seafloor) since quantities in the past were reported as flow rates and the durati on was not reported. The new permit requires permittees to report the volumes of these discharg es 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. Th ese discharges can incl ude ethylene glycol, lubricants, fuels, biocides, surfactants, detergen ts, corrosion inhibitors, cl eaners, solvents, paint cleaners, bleach (chlorine), dispersants, coagulants, oil and grease, suspended solids, bacteria, cement, cement extenders, and accelerators. Th ese discharges are generally limited to the immediate discharge area (with in 100 m of the facility).

Existing data are inadequate for the quantification of potential bioaccumulation from exposure to discharges from exploratory oil drilling operation s. 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, se ttling, and diffusion. Expl oratory drilling solids deposition and accumulation is generally limited to the immediate discharge area (within 100 m of the facility). At present, the area-wide la rge-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 e ffect on the environment due to deposition of drilling-related materials on the s eafloor. Drill cuttings will ra pidly settle to the seafloor upon discharge, where the other discharges will rema in in the water column for a longer period of time. These discharges tend to be diluted ra pidly following discharge; however, dilution isODCE for Arctic NPDES General Permit 1/24/06
10-3 dependent on the density, depth, and current sp eed of the waterbody. Of the three disposal methods available (open-water, above-ice, and below-ice), below-ice di sposal 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 colum n, 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 prin ciples and studies of other, related materials. Seve ral broad findings are suggested, but the data for a quantitative assessment of their importance are lacking. Chem ical transport will most likely arise from
oxidation/reduction reactions that occur in sediment s. Changes in redox potentials will effect the speciation and physical distribut ion (i.e., sorption-desorptio n reactions) of discharged
constituents.

Biological transport includes bioa ccumulation in soft or hard ti ssues, biomagnification, ingestion and excretion in fecal pellets, and physical reworking to mix solids into the sediment (bioturbation). The most effective way to monito r the biological effects of drilling discharges is to take quantitative samples of the benthic in fauna (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 assessme nt of their importance are lacking.
Bioaccumulation of a number of metals from ex posure to muds and mud components has been demonstrated in the laboratory and in the fiel d. Short-term laboratory experiments and field exposures indicate that tissue enri chment factors were generally le ss than an order of magnitude, with the exception of barium and chromium. Ho wever, 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 quali tatively demonstrated, but cannot be assed quantitatively at this time. Bioaccumulation of or ganics from drilling flui ds, 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 compone nt substances indicate th at a variety of their
toxic constituents can be bioaccumulated. None theless, only a qualitative conclusion may be
reached

10.3. CRITERION 3

The composition and vulnerability of th e biological communities which may be exposed to such pollutants, including the presence of unique species or communities of species, the presence of species identi fied as endangered or threatened pursuant to the Endangered Species Act, or the pres ence of those species critical to the structure or function of the ecosystem, such as those important for the food chain.

During exploratory drilling, muds a nd cuttings are typically discharg ed onto sea ice. This may block sunlight and reduce photosynthesis of pl ankton in the water colu mn in the immediate vicinity of the drill site.ODCE for Arctic NPDES General Permit 1/24/06
10-4 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 delineati on wells) indicates that less th an 0.0001 percent of the area of coverage would receive deposition of drilling mu d in amounts thought to have an adverse impact on benthic communities [i.e., 1 cm (0.4 in)]. Ho wever, 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 w ill 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 larv al stages and planktonic organisms are the most sensitive of the Alaskan species that have been ev aluated. It is unlikely that organisms would be exposed for periods of time typically used to determine acute toxic ity since drilling mud discharges are episodic with durations of onl y a few hours. Additionally, recovery of the affected benthic organisms likely would occur w ithin 4 months (Currie and Isaacs, 2004) to 2 years after the termination of discharges.

Discharges may have potential toxi c effects to fishes. Water quality tests indicate that lethal concentrations are generally present only within a few meters of the discha rge 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 sp ecies. Demersal eggs could be smothered if discharge of solids occurs in a spawning area during egg producti on. While no specific demersal fish spawning
locations have been identified in any of the Arctic areas of co verage, a number of important species, including most cottids and eelpout, pos sess demersal eggs. Although unlikely during exploratory activities in the Area of Coverage due to the anticipa ted 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 b ecause 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 explor atory drilling to fish sp ecies. Little effect to fish species was noted in depths of 66 ft or sh allower with dissipating tidal or current action. The most common effect to fishes would be disp lacement 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-cove red waters are presently restrict ed; therefore, the likelihood that fishes would be exposed to discharges during their critical overwintering period for relatively long periods of time in areas of litt le 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 vulne rability to potentially adverse factors associated to a large ex tent with oil and gas exploration. Discharges from drilling operations during exploration typi cally disperse rapidly in the surrounding water, although some may be deposited on the bottom near drill si tes. 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 pr ojected drill sites under this general permit.ODCE for Arctic NPDES General Permit 1/24/06
10-5 Additionally, drill stru ctures are likely to be quite dispersed; thus, disc harges are not likely to cause significant effects either through direct cont act 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 rec over from the minor effects that may result at each site.

Whales are seasonal feeders, obtaining thei r 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 containi ng potential prey, the episodic nature of the discharges, the low concentrations of metals in the discharge, and the mo bility of whales and their prey, the discharge is not like ly to adversely affect the listed whale species. It is likely that whales will avoid the activity occurring in the drilling areas and thus a void contact with prey residing within the more concentrated portions of the plume during discharge. The majority of bowhead whales exposed to recordings of drillshi p noise in the Area of Coverage oriented away
from the noise source. Noise le vels eliciting an a voidance 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 th e 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 wh ales), and one pinniped (Steller sea lion). These species live or spend a sign ificant 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 potentia l 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 specie s, 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 sp awning 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 Is land, Demarcation Bay, Elson Lagoon, and an area approximately 25 km (13.5 nmi) southwest of Wain wright in water depths of 11 to 13 m (36 to 43 ft).

Larger river systems and estuaries provide impor tant spawning and rearing areas for anadromousODCE for Arctic NPDES General Permit 1/24/06
10-6 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 dete rminant 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 a nd fast ice) changes seas onally. 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 feed ing habitat for gray whales. Kasegaluk Lagoon and Peard Bay is used by be luga 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 cons idered a calving area for the
walrus.

The coastal waters are primary habitat for ne sting, molting, feeding, and resting activities of migratory marine birds. Coasta l tundra and delta areas are al so important nesting areas for waterfowl. Eiders, terns, gulls, a nd guillemots nest on barrier islands.

Designated critical habitat (m olting 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 nes ting areas on the Yukon-Kuskokwim
delta and areas on the north side of the Al aska Peninsula (Izembek Lagoon, Nelson Lagoon, and Seal Islands) where Steller’s eide rs molt, winter, and stage during spring migration. The region surrounding Barrow has been identifi ed 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 y ear, 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.ODCE for Arctic NPDES General Permit 1/24/06
10-7 There is no designated critical habitat for the Steller sea lion within the area of coverage.

In order to protect the surroundi ng biological community, the permit prohibits from discharges of muds and cuttings in the following areas:

• In water depths less than 5 m (as me asured from mean lower low water);

• Between the shore (mainland and the ba rrier islands) and the 5-m isobath;

• Within 1000 meters of the Steffansson S ound Boulder Patch (near the mouth of the Sagavanirktok River) or between individua l units of the Boulder Patch where the separation between units is greate r 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, nation al and historic monuments, national seashores, wilderness areas, and coral reefs.

No marine sanctuaries or other special aqua tic 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 lik ely to be adversely impacted by exploratory drilling operati ons. The “Boulder Patch” area located near the Sagavanirtok River is recognized as an importa nt benthic habitat, primarily due to habitat provided by hard substrates and associated algal beds. In order to protect the Boulder Pa tch, the permit prohibits from discharges of muds and cuttings with in 1000 m of the Steffan sson Sound Boulder Patch (near the mouth of the Sagavani rktok River) or between individua l units of the Boulder Patch where the separation between units is gr eater 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 ex ploratory phase in the Arctic lease sales. The hazard associated with consuming fish and shel lfish contaminated with metals or petroleumODCE for Arctic NPDES General Permit 1/24/06
10-8 hydrocarbons is expected to be low. The reas ons for this assessment are: bioconcentration factors for heavy metals other than methylmerc ury 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 disc harges 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 comme rcial fishing, including finfishing and shellfishing.

The Colville River delta fisheries include two co mmercial 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 expect ed to adversely affect the quantity or quality of fish harvested in these fisheries.

10.8. CRITERION 8

Any applicable requirements of an a pproved Coastal Zone Management Plan.

Waste discharges associated with oil and gas explor ation 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 re lating to the effects of the discharge.

10.10. CRITERION 10

Marine water quality criteria deve loped pursuant to Section 304(a)(I)

The discharge of drilling muds in to water depths greater than 5 m is expected to comply with water quality criteria at the edge of a 100-m mixing zone.ODCE for Arctic NPDES General Permit 1/24/06
11-1 

## 11.0 REFERENCES

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. Alaska Department of Natural Resources, Di vision of Oil and Gas, Anchorage, AK. July 15, 1999.

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Armstrong, T., B. Roberts, and C. Swithinbank. (1973). Illustrated Glossary of Snow and

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Amstrup S.C., G.M. Durner, and T.L. McDonald. (2000). Estimating Potential Effects of Hypothetical Oil Spills from the Liberty Oil Production Island on Polar Bears

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Battelle. (1984). Final report for research on organic ch emical characterization of diesel and mineral oils used as drilling mud additives . Prepared for Offshore Operators Committee, Environmental Subcommittee. Battelle New England Marine Research Laboratory, December 1984.

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Braun, G.M. (1985). The structure of an Arctic shallow benthic community: Effects of ice gouging . Masters thesis. Oregon State University. 119 pp.ODCE for Arctic NPDES General Permit 1/24/06
11-2 Breteler, R.J., P.D. Boehm, J.M. Neff, and A.G. Requejo. (1984). Acute Toxicity of Drilling Muds Containing Hydrocarbon Add itives and their Fate and Partitioning between Liquid, Suspended and Solid Phases . Final Report to American Petroleum Institute, Washington, DC.

Broad, A.C., H. Koch, D.T. Mason, D.M. Petri, D.E. Schneider, and E.J. Taylor. (1978). Environmental assessment of selected habitats in the Beaufort Sea littoral system . In : Environmental Assessment of the Alaska n Continental Shelf. Annual reports of principal investigators for the year ending March 1978. NOAA, OCSEAP, Boulder.
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Broad, A.C. (1979). Environmental assessment of select ed habitats in the Beaufort and Chukchi littoral systems . pp. 36 1-544. In : Environmental Assessment of the Alaskan
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Carey, A.G. Jr., R.E. Ruff, J.G. Castillo, and J.J. Dickinson. (1974). Benthic ecology of the western Beaufort Sea continental margin: Preliminary results . pp. 665-680. In : The Coast and Shelf of the Beaufort Sea. J. C. Reed and J.E. Sater (eds.). The Arctic Institute of North America, Arlington, VA.

Carey, A.G. Jr., and R.E. Ruff. (1977). Ecological studies of the benthos in the western Beaufort Sea with special re ference to bivalve molluscs . pp. 505-530. In: Polar Oceans. M.J. Dunbar (ed.). The Arctic Institute of North America, Calgary, Alberta.

Carey, A.G., Jr. (1978). The distribution, abundance, diver sity, and productivity of the western Beaufort Sea benthos . pp. 127-252. In : Environmental assessment of the Alaskan continental shelf. Annual reports of principal investigators for the year ending March 1978. Volume IV: Receptors. NOAA/BLM, Boulder, CO.

Carls, M.G., and S.D. Rice. (1981). Toxicity of Oil Well Drilli ng Muds to Alaskan Larval Shrimp and Crabs . Final Report for Outer Continental Shelf Energy Assessment Program. U.S. Department of the In terior, Bureau of Land Management, Washington, DC.

Carr, R.S., L.A. Reitsema, and J.M Neff. (1980). Influence of a Used Chrome Lignosulfonate Drilling Mud on the Sruvival , Respiration, Feeding Activity, and Net Growth Efficiency of the Opposum Shrimp (Mysiopsis almyra ) . In : Symposium –
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Carr, R.S., W.L. McCullock, and J.M. Neff. (1982). Bioavailability of Chromium from a used Chrome Lignosulfonate Mud for Fi ve Species of Marine Invertebrates . Marine
Research 6 :189-203.ODCE for Arctic NPDES General Permit 1/24/06
11-3 CENTEC. (1984). Results of laboratory analysis and findings performed on drilling fluids and cuttings . Prepared for U.S. Environmental Protection Agency, Effluent and Guidelines Division, Energy and Mining. CENT EC Analytical Services, Washington, D.C. 51 pp. + appendices.

Choof, B. (1991). Personal communication (phon e by Mr. Tad Deshler, Tetra Tech, Inc., Redmond, WA). Minerals Management Serv ice, Anchorage, AK. October 3, 1991.

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Conklin, P.J., D.G. Doughtie, and K.R. Rao. (1980). Effects of Barite and Used Drilling Muds on Crustaceans, with Particular Reference to the Grass Shrimp, Palaemonetes pugio ) . In : Symposium – Research on Environm ental Fate and Effects of Drilling Fluids and Cuttings. Sponsored by API, Lake Buena Vista, Florida, January 1980.

Craig, P.C. (1984). Fish use of coastal waters of th e Alaskan Beaufort Sea: A review

. Trans. Am. Fish. Soc. 113:265-282.

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FIGURESODCE for Arctic NPDES General Permit 1/24/06 [page left blank intentionally]ODCE for Arctic NPDES General Permit1/24/06A-1Figure 1-1. Arctic NPDES General Permit Area of CoverageODCE for Arctic NPDES General Permit1/24/06A-2Figure 3-1. Approximate Patternof Initial Particle Deposition. (Houghton et al., 1981)ODCE for Arctic NPDES General Permit1/24/06A-3ODCE for Arctic NPDES General Permit 1/24/06
A-4 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06 APPENDIX B

TABLESODCE for Arctic NPDES General Permit 1/24/06 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
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 Seawat er/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 Fr eshwater 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 barrelODCE for Arctic NPDES General Permit 1/24/06
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-6ODCE for Arctic NPDES General Permit 1/24/06
B-3 Table 2-3. Concentration of Organic Pollu tants 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.ODCE for Arctic NPDES General Permit 1/24/06
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 – 33,000ODCE for Arctic NPDES General Permit 1/24/06
B-5

Table 2-5. Pollutant Concentrations in Untreated Deck Drai nage (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
151x10 4

- 568x10 4

<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.ODCE for Arctic NPDES General Permit 1/24/06
B-6 Table 2-6. Quantities of Discharg es in Arctic Alaska (1997-2003)

Discharge Quantity Discharged a

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 1/24/06
B-7

Table 3-1. Summary of Sedime nt 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 cl early distance-related patternODCE for Arctic NPDES General Permit1/24/06B-8Table 3-2. Summary Table of the Acute Lethal Toxicity of Drilling Fluid (USEPA, 1985)Number of 96-hour LC50Values (ppm)aNumber ofSpecies TestedNumber ofFluids TestedNumber ofTestsNotDeterminable< 100 100 - 999 1,000 – 9,999 10,000 – 99,999 > 100,000Phytoplankton 1 9 12 5 0 0 7 0 0InvertebratesCopepods 1 9 11 1 0 3 5 2 0Isopods 2 4 6 0 0 0 0 1 5Amphipods 4 11 22 0 0 0 0 7 15Gastropods 5 5 10 0 0 0 0 2 8DecapodsShrimp 9 23 66 0 0 6(1)b5 36 19Crab 8 18 32 1 0 0 3 17 11Lobster 1 2 7 0 0 0 1 3 3Bivalves 11 22 59 19d0 0 1 19 20Echinoderms 2 2 4 0 0 0 0 1 3Mysids 4 17 64 2(1)d0 0 1 29 32Annelids 7 14 34 3d0 0 0 12 19Finfish 15 24 80 0 0 0 2 50 36TOTALS 48 40c303 31 (23)d0 4 – 9 25 179 171Percentages as afraction of the totalnumber of tests70 68415392e2% 0%2.4%(1%)b6% 46% 44%Average percentagein a category foreach group ofanimals5.3% 0%2.8%(2.1%)b9.4% 33% 50%Adapted from Petrazzuolo (1983)a Placement in classes according to LC50value.Lowest boundary of range ifLC50expressed as a range.Cited values if given as “>” “<”. There were 199 such LC50values; 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 drilling fluids used anddischarged 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 wereall supplied by API. Their characteristics were very similar and they mayhave 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 Permit1/24/06B-9Table 3-3. Reported Toxicities ofSynthetic-Based Drilling Fluids (LC50s ) (USEPA, 2000a)Algae Mollusc Copepod Amphipod Shrimp FishDrillingFluidSkeletonemacostatumAbra albaAcartiatonsaAmpeliscaabditaLeptcheirusplumulosusRhepoxyniusabroniusCorophiumvolulatorMysidopsisbahiaFundulusgrandisBase Fluid with Natural Sediment (LC50)Diesel ND ND ND0.7 ml/kg1.0 ml/kg879 mg/kg850 mg/kg 24mg/kg 840 mg/kg ND NDEMO ND ND ND 575 mg/kg 251 mg/kg 239 mg/kg 7146 mg/kg ND NDIO2,050 mg/L300 mg/L>10,000mg/L3.0 ml/kg4.0 ml/kg3121 mg/kg3.7 ml/kg2944 mg/kg299 mg/kg7,100 mg/L>30,000mg/kgNDNDPAO 3,900 mg/L 7,900 mg/L>50,000mg/L12.5 ml/kg13.4 ml/kg10,690mg/kg9,636 mg/kg 975 mg/kg3.0 ml/kg12.0 ml/kg>30,000mg/kgND NDEster 60,000 mg/L>100,000mg/L50,000 mg/L ND ND ND ND ND NDAcetal >100,000 mg/L 549 mg/L>100,000mg/LND ND ND ND ND NDLAO >10,000 mg/L 1,021 mg/L>10,000mg/LND ND ND ND ND NDWhole Fluid with Natural Sediment (LC50)Diesel ND ND ND 1.5 ml/kg 9.4 ml/kg ND ND ND NDIO ND 303 mg/kg ND 1.5 ml/kg 2.3 ml/kg ND 7,131 mg/kg ND NDPAO 82,400 mg/L572 mg/kg7000 mg/L>50,000mg/L3.7 ml/kg 36.5 ml/kg ND>10,000mg/kgND >8.4 % TPHEster ND ND34,000-145,000mg/LND ND ND ND ND NDLAO ND 277 mg/kg ND ND ND ND 1,268 mg/kg ND NDWhole Fluid - No Sediment (LC50)IOND ND ND ND ND ND ND56,500 – >106ppm(SPP)NDND No data PAO PolyalphaolefinEMO Enhanced mineral oil LAO Linear alpha olefinIO Internal olefin SPPSuspended particulate phaseODCE for Arctic NPDES General Permit 1/24/06
B-10 Table 3-4. OOC Model Input Parameters Held Constant

Discharge Conditions Duration (hours) 1.0 a 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/cm 3 ) 2.085
Initial Solids Concentrati on in Whole Mud (mg/L) 1,441,000

Mud Particle Distribution

Volume
Fraction in Settling Velocity

Class
Number Density (g/cm 3 ) Whole Mud (cm 3 /cm 3 ) (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 ( σ t ) 22.0 Density Gradient ( ∆σ t /m) +0.1

a All under-ice model runs omitted the effect of waves in the model.ODCE for Arctic NPDES General Permit 1/24/06
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 Zone a 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 Permit1/24/06B-12Table 3-6. Estimated Depth of Drilling Muds at theEdge of the Mixing Zonefor Open-Water DischargePercent of Average Total Discharge10 25 50 100 200 300 400 500Total Drilling Mud Discharged in Kilograms (Pounds)Water DepthandDischargeRate59,874(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)2,993,710(6,600,000)40 m1,000 bbl/h(159,091 L/h)0.81.93.77.314.621.929.236.520 m750 bbl/h(119,091 L/h)0.71.83.67.214.421.628.836.05 m500 bbl/h(79,545 L/h)0.030.080.150.30.60.91.21.5Note: Shaded areas indicate model scenariosthat predict a drilling mud depth of less than 1 cm in areas beyond the 100-m mixing zone boundary.ODCE for Arctic NPDES General Permit 1/24/06
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 Zone a 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 59 8,742 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 Permit1/24/06B-14Table 3-8. Estimated Depth of Drilling Muds at theEdge of the Mixing Zone for Below-Ice DischargePercent of Average Total Discharge10 25 50 100 200 300 400 500Total Drilling Mud Discharged in Kilograms (Pounds)Water DepthandDischargeRate59,874(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)2,993,710(6,600,000)40 m1,000 bbl/h(159,091 L/h)0.110.280.551.12.23.34.45.520 m750 bbl/h(119,091 L/h)0.0140.0350.070.140.280.420.560.705 m500 bbl/h(79,545 L/h)0.0020.0050.010.020.040.060.080.10Note: Shaded areas indicate model scenariosthat predict a drilling mud depth of less than 1 cm in areas beyond the 100-m mixing zone boundary.ODCE for Arctic NPDES General Permit 1/24/06
B-15 Table 3-9. Summary of OOC Mode l 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 Zone a 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 59 8,742 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 Met als in Barite (Kra mer 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 7 a 500 b

Cadmium 12 0.65 0.2-19 50 b

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 19 c <5-5 Zind 2,750 9.8 10-4,100 200 b

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 Mollu scs, Polychaete and Brittle Star Tissues (EG&G, 1982)

Pre-drilling Cruise Post-drilling Cruise I a Post-drilling Cruise II b 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 Permit1/24/06B-17Table 3-12. Summary of Metal Bioaccumulation Study Results (Petrazzuolo, 1983)Metals, Enrichment FactoraTestOrganismTestSubstance(ppm)ExposurePeriod(days)DurationPeriod(days)Ba Ca Cd Cr Cu Pb Sr ZnRef.bXC-polymerUnical fluid20static0 1(50,000) 3.2 1.2 2.0 1.6(100,000) 6.4 1.8 2.2 1.3Onisimus sp.,Boekosimus sp.Whole Animalnot gutted(200,000) 6.0 1.4 1.5 1.5Barite 25 -- 150 1.350 -- 350 1.95 14 2.2 1.8PalaemonetespugioWhole Animalnot gutted507, 48-hourreplacement14 29 2.2Barite 0500 7.7 1.2-2.5500 13 1.9-2.8CarapaceHepatopancreasAbdominalmuscle5008 dayspost-ecdysis(48-hourreplacement)12 1.5-2.8Barite 106 0500 60-100 0.07500 70-300 1CarapaceHepatopancreasAbdominalmuscle500 50-120 112.7 lb/gallignosulfonatefluid, MAF(Cr=1.4 ppm)1 -- 6.6 3Ferrochromelignosulfonate(Cr=0.7 ppm)13(Cr=6.0 ppm) 64Mytilus edulisSoft tissueCrCl3(Cr=0.6 ppm)50ODCE for Arctic NPDES General Permit1/24/06B-184, static -- 1.4 1.7 412.7 lb/gallignosulfonatefluid, MAF(50,000)4 1.1 1.216, static 2.5-- 1 1.713.4 lb/gallignosulfonatefluid MAF(100,000)-- 14 1.6-- 4.3Rangea cuneataSoft tissue(layered solidphase)4, dailyreplacement1 2.09.2 lb/gal spudfluid(40,000 MAF)10, static 0 2.1 1.1(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-hourreplacement0 7.412.7 lb/gallignosulfonatefluid(40,000 MAF)10, static 0 2.3 1.4(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 24CrassostreagigasSoft tissue(80,000 SPP)4, 24-hourreplacement0 3617.4 lb/gallignosulfonatefluid(40,000 MAF)10, static 0 0.56 1.0(20,000 MAF) 14 0 2.1CrassostreagigasSoft tissue(cont.)(40,000 MAF) 14 0 2.2ODCE for Arctic NPDES General Permit1/24/06B-19Uncirculatedlignosulfonatefluid5(1,000) 28 0 8.8 2.6(1,000) 28 0 10 1.2Low densitylignosulfonatefluid(1,000) 14 -- 1.627 -- 2.1-- 15 2.3(1,000) 14 -- 227 -- 2-- 15 2FCLS(30) 14 -- 5.7-- 14 3.2(100) 14 -- 6.0-- 14 5.2(1,000) 14 -- 7.2PlacopectenmagellanicusKidneyAdductorKidneyAdductor-- 14 6.0XC-polymerfluid36, 48-hourreplacement6(5,000) 3.3 1.1 1.25 1.2Myoxocephalusquadricornis(gutted)(10,000) 2.9 3.1 1.7 1.2aEnrichment Factor = Concentration in exposed group/concentration in controls.bReferences: 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 fractionSPP – suspended particulate phaseFCLS – ferrochrome lignosulfonateODCE for Arctic NPDES General Permit 1/24/06
B-20 Table 3-13. Depuration of Metals Bioa ccumulated during Exposure to Drilling Fluids or Components a (Petrazzuolo, 1983)

Test Species Test
Substance Exposure
Period (days) Metal Tissue Depuration
Level b Depuration
Period (days)

Ba -90% 7 Palaemonetes pugio BaSO 4 7

Sr Whole animal,

not gutted -90% 7

SLF (LSP) 1-4 Cr -(40-65%) 7

4 Cr -75% 4 MDLF (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 fluidODCE for Arctic NPDES General Permit1/24/06B-21Table 4-1. Fishes Located in the Area of CoverageFreshwater Anadromous or Resident MarineCommonNameScientific Name Common Name Scientific Name Common Name Scientific NameArctic graylingRound whitefishBurbotSlimy sculpinLake troutArctic blackfishNorthern pikeLongnose suckerArctic lampreyThymallus arcticusProsopium cylindraceumLota lotaCottus cognatusSalvelinus namaycushDallia pectoralisEsox luciusCatostomus catostomusLampetra japonicaArctic charDolly VardenArctic ciscoLeast ciscoBering ciscoBroad whitefishHumpback whitefishCum salmonRainbow smeltBoreal smeltNinespine sticklebackThreespine sticklebackPink salmonCoho salmonChinook salmonSockeye salmonSalvelinus alphinusSalvelinus malmaCoregonus autumnalisCoregonus sardinellaCoregonus lauretteCoregonus nasusCoregonus pidschianOnchorynchus ketaOsmerus mordax dentexOsmerus eperlanusPungitius pungitiusGastrosteus aculeatusOnchorynchus gorbuschaArctic flounderStarry founderArctic codSaffron codCapelinSnailfishPacific sandlancePacific HerringSlender eelblennyStout eelblennyEelpoutArctic sculpinSpotted SnailfishSculpinSaffron codFourhorn sculpinArctic staghorn sculpinShorthorn sculpinHameconYellowfin soleLiopsetta glacialisPlatichthys stellatusBoreogadus saidaEleginus gracilisMallotus villosusLiparus sp.Ammodytes hexapterusClupa harengusLurnpenus fabricilLumpenus mediusLycodes spp.Myoxocephalus scorpiodesLiparus callyodonMyoxocephalus sp.Eleginus gracilisMyoxocephalus quadricornisGymnocanthus tricuspisMyoxocephalus scorpiusArtediellus scaberLimanda asperaODCE 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 +

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-

- +

+

+

+ *

+ *

+

- +

+ *

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+ *

+ *

+

+

+

+ *

+ *
*

+ *
*

+

+

+ +

+

+

+ *

+ *

+

- +

+ *

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+ *

+ *

+

+

+

+ *

+ *
*

+ *
*

+

+

+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 AreaODCE 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 AreaODCE 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 Habita t 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 DeterminedODCE for Arctic NPDES General Permit 1/24/06
B-27 Table 4-8. Essential Fish Habitat fo r 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)ODCE for Arctic NPDES General Permit 1/24/06
B-28 Table 9-1. Trace Metal Leach Factor s 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 Sea a

Metal Mean Solid Phase (mg/kg) Mean Liquid Phase (mg/L) Partition
Coefficient b

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 Sea c 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, 2004cODCE for Arctic NPDES General Permit1/24/06B-29Table 9-3. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing Zone Boundary)to Marine Water Quality CriteriaCase 1: Whole mud metal concentration as dissolved metal concentration.Predicted Concentration atMixing Zone Boundarye(μg/L)MaximumWholeMudEstimatedDissolvedMetalAcuteMarineChronicMarineOpen-Water Discharge,Current Speed of 10 cm/secBelow-Ice Discharge, CurrentSpeed of 2 cm/secConc.aConc.bAWQCcAWQCcWater Depth (m)Metal(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 20 5Arsenic 7,100 7,100 69 36 4 10 20 4 7 7Barium 359,747,000 359,747,000 NA NA 225,972 481,589 1,010,525 185,628 341,965 370,110Cadmium 1,100 1,100 40 8.8 0.7 1.5 3.1 0.6 1.0 1.1Chromium 240,000 240,000 1,100 50 151 321 674 124 228 247Copper 18,700 18,700 4.8 3.1 11.7 25.0 52.5 9.6 17.8 19.2Iron 15,344,300 15,344,300 NA NA 9,638 20,541 43,102 7,918 14,586 15,786Lead 35,100 35,100 210 8.1 22.0 47.0 98.6 18.1 33.4 36.1Mercury 100 100 1.8 0.94 0.06 0.13 0.28 0.05 0.10 0.10Nickel 13,500 13,500 74 8.2 8.5 18.1 37.9 7.0 12.8 13.9Zinc 200,500 200,500 90 81 126 268 563 103 191 206aMaximum measured whole mud metal concentrations in drilling muds discharged in Alaskan waters (Table 2-2)bThe assumption for this comparative analysis is that all the metals in the whole mud are available to dissolve in the water column.cAlaska Marine Water Quality Criteria – these values are all dissolved.dThe predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appropriate modified OOCmodel-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.ODCE for Arctic NPDES General Permit1/24/06B-30Table 9-4. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing Zone Boundary)to Marine Water Quality CriteriaCase 2: Dissolved fraction estimated frommaximum trace metal leach factors in Table 9-1.Predicted Concentration at Mixing Zone Boundaryc(μg/L)MaximumWholeMudEstimatedDissolvedMetalAcuteMarineChronicMarineOpen-Water Discharge,Current Speed of 10 cm/secBelow-Ice Discharge, CurrentSpeed of 2 cm/secConc.aConc.AWQCbAWQCbWater Depth (m)Metal(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 20 5Arsenic 7,100 58 69 36 0.04 0.08 0.16 0.03 0.05 0.06Barium 359,747,000 2,122,507 NA NA 1,333 2,841 5,962 1,095 2,018 2,184Cadmium 1,100 264 40 8.8 0.2 0.4 0.7 0.1 0.3 0.3Chromium 240,000 15,360 1,100 50 10 21 43 8 15 16Copper 18,700 281 4.8 3.1 0.2 0.4 0.8 0.1 0.3 0.3Iron 15,344,300 7,365,264 NA NA 4,626 9,860 20,689 3,800 7,001 7,577Lead 35,100 1,193 210 8.1 0.7 1.6 3.4 0.6 1.1 1.2Mercury 100 6.4 1.8 0.94 0.004 0.01 0.02 0.003 0.01 0.01Nickel 13,500 1,188 74 8.2 0.7 1.6 3.3 0.6 1.1 1.2Zinc 200,500 1,123 90 81 0.7 1.5 3.2 0.6 1.1 1.2aMaximum measured whole mud metal concentrations in drilling muds discharged in Alaskan waters (Table 2-2)bAlaska Water Quality Criteria – these values are all dissolved.cThe predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appropriate modified OOCmodel-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.ODCE for Arctic NPDES General Permit1/24/06B-31Table 9-5. Comparison of Drilling Mud Predicted Dissolved Metal Concentrations (at Mixing Zone Boundary)to Marine Water Quality CriteriaCase 3: Dissolved fraction estimated frommean trace metal leach factors in Table 9-1.Predicted Concentration at Mixing Zone Boundaryc(μg/L)MaximumWholeMudEstimatedDissolvedMetalAcuteMarineChronicMarineOpen-Water Discharge,Current Speed of 10 cm/secBelow-Ice Discharge, CurrentSpeed of 2 cm/secConc.aConc.AWQCbAWQCbWater Depth (m)Metal(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 20 5Arsenic 7,100 36 69 36 0.02 0.05 0.10 0.02 0.03 0.04Barium 359,747,000 755,469 NA NA 475 1,011 2,122 390 718 777Cadmium 1,100 121 40 8.8 0.08 0.16 0.34 0.06 0.12 0.12Chromium 240,000 8,160 1,100 50 5 11 23 4 8 8Copper 18,700 118 4.8 3.1 0.07 0.16 0.33 0.06 0.11 0.12Iron 15,344,300 1,944,759 NA NA 1,253 2,670 5,603 1,029 1,896 2,052Lead 35,100 702 210 8.1 0.4 0.9 2.0 0.4 0.7 0.7Mercury 100 1.8 1.8 0.94 0.001 0.002 0.01 0.001 0.002 0.002Nickel 13,500 581 74 8.2 0.4 0.8 1.6 0.3 0.6 0.6Zinc 200,500 822 90 81 0.5 1.1 2.3 0.4 0.8 0.8aMaximum measured whole mud metal concentrations in drilling muds discharged in Alaskan waters (Table 2-2)bAlaska Water Quality Criteria – these values are all dissolved.cThe predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appropriate modified OOCmodel-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.ODCE for Arctic NPDES General Permit1/24/06B-32Table 9-6. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing Zone Boundary)to Marine Water Quality CriteriaCase 1: Total drilling cutting metal concentration as dissolved metal concentration.Predicted Concentration at Mixing Zone Boundaryd(μg/L)MaximumDrillingCutttingEstimatedDissolvedMetalAcuteMarineChronicMarineOpen-Water Discharge,Current Speed of 10 cm/secBelow-Ice Discharge, CurrentSpeed of 2 cm/secConc.aConc.bAWQCcAWQCcWater Depth (m)Metal(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 20 5Arsenic 10,600 10,600 69 36 7 14 30 5 10 11Cadmium 16,400 16,400 40 8.8 10.3 22.0 46.1 8.5 15.6 16.9Chromium 12,000 12,000 1,100 50 8 16 34 6 11 12Copper 55,300 55,300 4.8 3.1 34.7 74.0 155.3 28.5 52.6 56.9Lead 298,000 298,000 210 8.1 187.2 398.9 837.0 153.8 283.3 306.6Mercury 944 944 1.8 0.94 0.59 1.26 2.65 0.49 0.90 0.97Nickel 15,900 15,900 74 8.2 10.0 21.3 44.7 8.2 15.1 16.4Silver 574 574 1.9 -- 0.4 0.8 1.6 0.3 0.5 0.6Selenium 3,000 3,000 290 71 2 4 8 2 3 3Zinc 3,200,000 3,200,000 90 81 2,010 4,283 8,989 1,651 3,042 3,292aMaximum measured drilling cutting metal concentrations (Table 2-4)bThe assumption for this comparative analysis is that all the metals in the drilling cuttings are available to dissolve in the water column.cAlaska Marine Water Quality Criteria – these values are all dissolved.dThe predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appropriate modified OOCmodel-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.ODCE for Arctic NPDES General Permit1/24/06B-33Table 9-7. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing Zone Boundary)to Marine Water Quality CriteriaCase 2: Dissolved metal concentration is two ordersof magnitude lower than drilling cutting concentrations.Predicted Concentration at Mixing Zone Boundaryd(μg/L)MaximumDrillingCuttingEstimatedDissolvedMetalAcuteMarineChronicMarineOpen-Water Discharge,Current Speed of 10 cm/secBelow-Ice Discharge, CurrentSpeed of 2 cm/secConc.aConc.bAWQCcAWQCcWater Depth (m)Metal(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 20 5Arsenic 10,600 106 69 36 0.1 0.1 0.3 0.1 0.1 0.1Cadmium 16,400 164 40 8.8 0.1 0.2 0.5 0.1 0.2 0.2Chromium 12,000 120 1,100 50 0.1 0.2 0.3 0.1 0.1 0.1Copper 55,300 553 4.8 3.1 0.3 0.7 1.6 0.3 0.5 0.6Lead 298,000 2,980 210 8.1 1.9 4.0 8.4 1.5 2.8 3.1Mercury 944 9.44 1.8 0.94 0.01 0.01 0.03 0.005 0.01 0.01Nickel 15,900 159 74 8.2 0.1 0.2 0.4 0.1 0.2 0.2Silver 574 574 1.9 -- 0.004 0.01 0.02 0.003 0.01 0.01Selenium 3,000 30 290 71 0.02 0.04 0.08 0.02 0.03 0.03Zinc 3,200,000 32,000 90 81 20 43 90 17 30 33aMaximum measured drilling cuttings metal concentrations (Table 2-4)bThe assumption for this comparative analysis is that the metalsin the dissolved fraction are two orders of magnitude lower than the drilling cuttings(divide by 100).cAlaska Water Quality Criteria – these values are all dissolved.dThe predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appropriate modified OOCmodel-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.ODCE for Arctic NPDES General Permit1/24/06B-34Table 9-8. Comparison of Drilling Cutting Predicted Dissolved Metal Concentrations (at Mixing Zone Boundary)to Marine Water Quality CriteriaCase 3: Dredged material partition coefficients are used to estimate dissolvedmetal concentrations in drilling cuttings.Predicted Concentration at Mixing Zone Boundaryd(μg/L)MaximumWholeMudEstimatedDissolvedMetalAcuteMarineChronicMarineOpen-Water Discharge,Current Speed of 10 cm/secBelow-Ice Discharge, CurrentSpeed of 2 cm/secConc.aConc.bAWQCcAWQCcWater Depth (m)Metal(μg/kg) (μg/L) (μg/L) (μg/L) 40 20 5 40 20 5Arsenic 10,600 13 69 36 0.01 0.02 0.04 0.01 0.01 0.01Cadmium 16,400 21.3 40 8.8 0.01 0.03 0.06 0.01 0.02 0.02Chromium 12,000 1.2 1,100 50 0.001 0.002 0.003 0.001 0.001 0.001Copper 55,300 5.5 4.8 3.1 0.003 0.01 0.02 0.003 0.01 0.01Lead 298,000 59.6 210 8.1 0.04 0.08 0.17 0.03 0.06 0.06Mercury 944 0.944 1.8 0.94 0.001 0.001 0.003 0.0005 0.001 0.001Nickel 15,900 15.9 74 8.2 0.01 0.02 0.04 0.01 0.02 0.02Silver 574 0.6 1.9 -- 0.0004 0.001 0.002 0.0003 0.001 0.001Selenium 3,000 3 290 71 0.002 0.004 0.01 0.002 0.003 0.003Zinc 3,200,000 1,600 90 81 1 2 4 1 2 2aMaximum measured drilling cuttings metal concentrations (Table 2-4)bThe assumption for this comparative analysis is that the metalsin the drilling cuttings partition similar to that of dredged materials dumped at sea. Totaldrilling cutting concentrations are multiplied by the partition coefficients in Table 9-1.cAlaska Water Quality Criteria – these values are all dissolved.dThe predicted dissolved-metal concentrations calculated by dividing the estimated dissolved-metal concentration by the appropriate modified OOCmodel-predicted dilution factors for open-water and below-ice discharges in Tables 3-5 and 3-7, respectively.ODCE for Arctic NPDES General Permit 1/24/06
B-35 Table 9-9. Comparison of Sanitary Was te Predicted Total Residual Chlorine Concentrations (at Mixing Zone Boundary) to Marine Water Quality Criteria

Predicted Concentration at Mixing Zone Boundary a ( μ g/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, respectivelyODCE for Arctic NPDES General Permit 1/24/06
B-36 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06 APPENDIX C

NPDES GENERAL PERMIT FOR OIL AND GAS EXPLORATION
IN THE ARCTICODCE for Arctic NPDES General Permit 1/24/06 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06 APPENDIX D

CALCULATION OF SOLIDS DEPOSITION MULTIPLIERSODCE for Arctic NPDES General Permit 1/24/06 [page left blank intentionally]ODCE for Arctic NPDES General Permit 1/24/06
D-1 The OOC model scenarios used in the ODCE predict the deposition of solids after one hour of discharge. This time period was c hosen to be consistent with the input parameters of earlier modeling efforts on explor atory oil and gas ODCEs. An interval of one hour is not sufficient time to discharge all of the drilling m uds 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 th e completion of an exploratory well, an estimate for the average amount of drilling m uds produced by each exploratory well is required. Estimates of drilling mud producti on 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 thickne ss of drilling mud upon completion of an exploratory well, a multiplier must be cal culated 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 a bove) by the production period predicted after one hour, which is ca lculated 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 S ection 3 for the case runs which included a discharge rate of 1,000 bbl/h were mu ltiplied by 2.613 to represent the maximum completion-of-well values for an average expl oratory well drilling in the Chukchi Sea. This method of estimating mud accumulation assumes that area deposition patterns will be unchanged for discharges of different qua ntities 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, eith er for solids or the dissolved fraction, are unaffected by the differences between the modeled and actual discharge amounts and would not be subject to th e multiplier calculated above.

The following table shows the multipliers for f our discharge rates in the Beaufort and Chukchi seas. [In this ODCE, multipliers for the Chukchi Sea were applied to the entire Area of Coverage.]ODCE for Arctic NPDES General Permit 1/24/06
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 10.453ODCE for Arctic NPDES General Permit 1/24/06 APPENDIX E

FACT SHEET
FOR
NPDES GENERAL PERMIT FOR OIL AND GAS EXPLORATION
IN THE ARCTICODCE for Arctic NPDES General Permit 1/24/06 [page left blank intentionally]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.gov2 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 explora tion 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 electronica lly 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.ep a.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 Distri ct 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 E xploration 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 Program4 

### TABLE OF CONTENTS

I. APPLICABILITY AND NOTIF ICATION 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 E xpiration...................................................................................................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 Calculations5 

### 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-26 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). Explor atory 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 re gulations 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 by7 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, and8 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 the9 identification or protection of biol ogical 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 wellhole 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 of10 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 particularpollutant 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 WLA13 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 criteri a. 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 fo r 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 be15 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 except16 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, Bering19 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 520 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) and22 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

7-day average 45 mg/L BOD 5
24-hour average 60 mg/L

30-day average 30 mg/L

7-day average 45 mg/L TSS

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. EP A 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 not25 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 on26 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. EP A 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 static27 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 unitprocesses 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 industry28 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 requires29 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., BOD 5 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 biol ogical 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 ma nagement 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 to32 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 no34 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 Meeti ng 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, Offi ce 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 a ssociated 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 SeaPage B-2 Figure B-2. Arctic General Permit Area of CoveragePage 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/l 5 Drilling Fluids and Drilling Cuttings (001)

Total aromatic hydrocarbons (TAH) 10 μg/l 6

Total aqueous hydrocarbons (TAqH) 15 μg/l 5 Deck Drainage (002) Total aromatic hydrocarbons (TAH) 10 μg/l 6

Total Residual Chlorine 2.0 μg/l

14 FC/100 ml 2 Sanitary Waste (003) Fecal Coliform Bacteria 1
43 FC/100 ml 3

Total aqueous hydrocarbons (TAqH) 15 μg/l 5 Domestic Waste (004) Total aromatic hydrocarbons (TAH) 10 μg/l 6

Total aqueous hydrocarbons (TAqH) 15 μg/l 5 Excess Cement Slurry (012) Total aromatic hydrocarbons (TAH) 10 μg/l 6

All pH 6.5 - 8.5 4

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 aPage 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:

C d x V d = (C
e x V e ) + (C
u x V d ),

where, C d is the projected receiving water concentration, V d is the volume of the receiving water used for mixing (i.e., the mixing zone dilution), C
e is the maximum effluent concentration, V
e is the estimated volume of effluent discharged, and C
u is the existing receiving water concentration prior to effluent discharge.

The predicted receiving water concentration (C d ) can be calculated by rearranging the basic mass balance equation, as follows:Page C-3 C d = (C
e x V e ÷ V d ) + C
u ,

where the ratio of the effluent volume to the receiving water volume (V
e ÷ V d ) is the dilution ratio. The dilution ratio is determined from computer modeling performed by ADEC.

If C
u is equal to 0, the equation becomes

C d = C e x V e ÷ V d

.

b. The criterion is then compared to the maximum projectedreceiving 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 disc harged 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
C d

= (C

e ÷ dilution ratio) + C

u C d 0.002 mg/L

maximum effluent concentration C

e = TBEL C
e 1.0 mg/L

Technology-based effluent limit TBEL 1.0 mg/L

dilution ratio 500:1

background concentration C

u 0 mg/L

The projected receiving water concentration (C d ) 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 = C
e = [C d - C

u ] x dilution ration WLA
c 1.0 mg/L

chronic criterion C d 0.002 mg/L

dilution ratio 500:1

background concentration C

u 0 mg/LPage 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[z 99 σ - 0.5 σ 2 ] MDL 1.6 mg/L

average monthly limit
AML = LTA

@ exp[z 95 σ n - 0.5 σ n 2 ] AML 0.8 mg/L

average annual effluent flow Q

e 0.00202 mgd

long term average
LTA
c = WLA
c @ exp[0.5 σ 4 2 - z 99 σ 4 ] LTA 0.53

chronic wasteload allocation WLA

c 1.0

z-score (99th percentile) z 99 2.326

z-score (95th percentile) z 95 1.645

coefficient of variation CV 0.6

popular variance

σ 2 = ln(CV 2 +1) σ 2 0.31

standard deviation

σ = ( σ 2 ) 0.5 σ 0.55

number of samples required per month n 4

σ n 2 = ln[(CV 2 ÷ n)+1] σ n 2 0.086

σ n = ( σ n 2 ) 0.5 σ n 0.29Page 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
C d

= (C

e ÷ dilution ration) + C

u C d 200 FC/100 mL

maximum effluent concentration C

e = TBEL C
e 200 FC/100 mL

Technology-based effluent limit TBEL 200 FC/100 mL

dilution ratio 0

background concentration C

u 0 FC/100 mL

criterion (in # 10% of samples) 43 FC/100 mL

projected receiving water concentration
C d

= (C

e ÷ dilution ration) + C

u C d 200 FC/100 mL

maximum effluent concentration C

e = TBEL C
e 200 FC/100 mL

Technology-based effluent limit TBEL 200 FC/100 mL

dilution ratio 0

background concentration C

u 0 FC/100 mL

The projected receiving water concentration (C d ) 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