OCS Report 

MMS 2007-041 

Supplement to Oil-Spill Risk Analysis: 

Beaufort Sea Planning Area, 

OCS Lease Sale 202 

U.S. Department of the Interior 

Minerals Management Service 

Environmental Division 

OCS Report 

MMS 2007-041

Supplement to the Oil-Spill Risk Analysis: 

Beaufort Sea Planning Area, 

OCS Lease Sale 202 

By: 

Walter R. Johnson 

Charles F. Marshall 

Eileen M. Lear (Editor)

U.S. Department of the Interior 

Minerals Management Service 

Environmental Division July 2007 

Contents 

Page 

Introduction..................................................................................................................................... 1 

Summary of the Proposed Action and Alternatives........................................................................ 1 

Oil-Spill Risk Analysis ................................................................................................................... 2 

Probability of Large Oil Spills Occurring.............................................................................. 2 

Discussion ...................................................................................................................................... 4 

References Cited ............................................................................................................................. 4 

iii 
List of Tables

Table Page 

1.R. Estimated Percent Chance of One or More Large Platform, Pipeline, and Total Spills 

for Lease Sale 202 and it’s Alternatives over the Life of the Project.....................................6 

20R-25R. Combined probabilities (expressed as percent chance) of one or more spills greater 

than or equal to 1,000 barrels, and the estimated number of spills (mean), occurring 

and contacting a certain environmental resource area over the assumed production 

life of the lease area . . . . 

20R. within 3 days ......................................................................................................................... 7 

21R. within 10 days ....................................................................................................................... 9 

22R. within 30 days ..................................................................................................................... 11 

23R. within 60 days ..................................................................................................................... 13 

24R. within 180 days ................................................................................................................... 15 

25R. within 360 days ................................................................................................................... 17 

29R-31R. Combined probabilities (expressed as percent chance) of one or more spills greater 

than or equal to 1,000 barrels, and the estimated number of spills (mean), occurring 

and contacting a certain land segment over the assumed production life of the lease 

area . . . . 

29R. within 60 days ..................................................................................................................... 19 

30R. within 180 days ................................................................................................................... 19 

31R. within 360 days ................................................................................................................... 19 

iv 
Introduction 

The Federal Government plans to offer U.S. Outer Continental Shelf (OCS) lands in the 

Beaufort Sea Planning Area for oil and gas leasing. Because oil spills may occur from 

activities associated with offshore oil exploration, production, and transportation resulting 

from these lease sales, the Minerals Management Service (MMS) conducts a formal oilspill risk analysis (OSRA) to support the environmental impact statement (EIS) and 

environmental assessments (EA’s) completed prior to conducting the proposed leasing of 

this area. An analysis for Beaufort Sea OCS Lease Sale 202 was previously conducted in 

2002 to estimate the risk of oil-spill contact to sensitive offshore and onshore 

environmental resources and socioeconomic features from oil spills accidentally occurring 

from OCS activities (Johnson et al., 2002). Because of new information regarding the 

fault-tree method of estimating oil-spill frequencies relevant to the Arctic (Bercha Group, 

2006), MMS analysts have new estimates for the number of spills occurring and contacting 

environmental resources over the assumed life of the lease area (combined probabilities). 

These new estimates are presented in this supplement as tables to replace the combined 

probability tables contained in the original 2002 OSRA report. For ease of comparison, 

the authors have retained the original table numbers but added an “R” to identify them as 

replacement tables; only tables that have changed are presented. 

Summary of the Proposed Action and Alternatives 

The proposed action is to lease OCS lands in the Beaufort Sea Planning Area. As shown 

in figure 1 of the 2002 OSRA report (Johnson et al., 2002), the study area for this analysis, 

which extends from latitudes 68.0o N. to 74.0o N. and from longitudes 134.0o W. to 176.0o

W., defines the geographic boundaries that encompass the environmental resource areas at 

risk from a hypothetical oil spill from OCS operations in the lease areas. 

The full sale area and four alternatives to the proposed action that were judged to be 

“economic” were analyzed in the 2002 OSRA. The four alternatives analyzed are the 

Barrow Subsistence Whale Deferral, Nuiqsut Subsistence Whale Deferral, Kaktovik 

Subsistence Whale Deferral, Eastern Bowhead Deferral. These alternatives were analyzed 

by using the conditional and combined probabilities (representing oil-spill occurrence and 

contact) relevant to only those portions of the hypothetical launch areas that overlay the 

respective areas—the remaining nondeferred areas. 

The proposed action would defer leasing within areas in which Barrow and Kaktovik 

residents conduct subsistence whaling. The MMS received several comments in response 

to the Request for Information that was published in the Federal Register on October 28, 

2005. Some of the comments expressed interest in leases within the whole Area of Call. 

That area (USDOI/MMS, 2006, Figure 1) includes 1,877 whole or partial blocks that 

encompass 9,770,000 acres (about.3,954,000 hectares). The MMS also received letters 

about the potential effects of operations in subsistence-whaling areas (USDOI/MMS, 2006, 

Appendix A). The subareas that would not be offered for lease by the proposed action 

consist of 54 whole or partial blocks, equaling approximately 259,000 acres, or 3 percent 

of the whole Area of Call. The deferrals were conceived as a way to reduce conflicts 

1 
between subsistence whalers and OCS operations. The deferral areas were discussed 

during public hearings on the Alaska North Slope and were the subject of comment letters 

on the multiple-sale Final EIS and Sale 195 Environmental Assessment. The deferrals 

were addressed recently in a letter about Sale 202 from the Alaska Eskimo Whaling 

Commission (AEWC) and about the 5-year program from U.S. Senator Murkowski. As 

explained in the AEWC letter (USDOI/MMS, 2006, Appendix A), the Barrow and 

Kaktovik whalers hunt within areas larger than the deferrals. The MMS believes that 

conflicts between subsistence whalers and OCS operations within that larger area (and 

within the subsistence-whaling areas for Nuiqsut) can be moderated through mitigation 

measures. 

Oil-Spill Risk Analysis 

The OSRA was conducted in three parts corresponding to different aspects of the overall 

problem: (1) the probability of large oil-spill occurrence, (2) the trajectories of large oil 

spills from hypothetical spill locations to various environmental resource areas, and (3) a 

combination of the first two to estimate the overall oil-spill risk of combined occurrence 

and contact if there is oil development. 

Probability of Large Oil Spills Occurring 

The MMS defines large oil spills as greater than or equal to 1,000 barrels (bbl). The 

probability of one or more large oil spills occurring assumes that spills are random events 

that occur independently of each other as a Poisson process. In this analysis, the 

probability of large oil spills occurring is based on oil-spill frequencies per barrel produced 

that are derived from a fault-tree method of estimating spill occurrence relevant to the 

Arctic (Bercha Group, 2006). The fault-tree method incorporated an analysis of worldwide 

and U.S. Outer Continental Shelf oil-spill statistics to evaluate applicability to lease sales 

in the Beaufort and Chukchi Seas. Annual frequencies of spills, by spill size per billion 

barrels (Bbbl) produced, were developed for the Beaufort Sea Lease Sale 202 for the years 

2019-2038. The resulting annual spill frequencies were weighted by annual production 

estimates to develop spill occurrence rates for platforms and wells (0.33 spills/Bbbl) and 

pipelines (0.20 spills/Bbbl); these rates were used in the OSRA Model. Only rates for 

spills of 1,000 bbl or greater were included in the analysis. 

Spill rates are expressed as number of spills/Bbbl, defined as 109

 bbl, of oil produced or 

transported. Only spills greater than or equal to 1,000 bbl are addressed because smaller 

spills may not persist long enough to be simulated by trajectory modeling. Another 

consideration is that a large spill is likely to be identified and reported; therefore, these 

records are more comprehensive than those of smaller spills. (Smaller spills are addressed 

in the EIS for each proposed action without the use of trajectory modeling.) 

Two basic criteria were used in selecting volume of oil handled as the exposure variable: 

(1) the exposure variable should be simple to define, and (2) it should be a quantity that 

can be estimated. The volume of oil produced or transported was the chosen exposure 

variable primarily for the following reasons: (1) historic volumes of oil produced and 

transported are well documented; (2) using these volumes makes the calculation of the 

2 
estimated oil-spill occurrence rate simple—the ratio of the number of historic spills to the 

volume of oil produced or transported; and (3) future volumes of oil production and 

transportation are routinely estimated. Estimates of volume to be developed for a proposed 

action, which were prepared by analysts in the MMS Resource Evaluation and Assessment 

Section, Alaska OCS Region, are derived from the assessment of oil resources by using 

comprehensive geological and geophysical databases and related models. In addition, the 

MMS analysts estimate other exposure variables, such as the number of platforms and size 

of pipelines, as a function of the volume of oil produced or transported. 

Fault Tree Analysis: During development of the final EIS for the Liberty Development 

and Production Plan (Beaufort Sea) in 2000, stakeholders expressed concern regarding the 

application of historical oil-spill data from the Gulf of Mexico (GOM) to the Beaufort 

OCS. Therefore, MMS used historical oil-spill data gathered from a multitude of sources. 

Because of this concern, the MMS sponsored a study regarding spill rates (Bercha Group, 

2002 and 2006). These studies examined alternative oil-spill occurrence estimators for the 

Beaufort and Chukchi Seas using a fault tree method. Various causes of spills were looked 

at in relation to their relevance to Arctic conditions. An assessment was made regarding 

the contribution of Arctic versus non-Arctic conditions. Because sufficient historical data 

on large offshore oil spills for these regions do not exist, a model based on fault tree 

methodology was developed and applied for this Beaufort multiple sale (Bercha Group, 

2002 and 2006). Using fault trees, oil-spill data from the GOM were modified and 

incremented to represent expected Arctic performance. 

Large Oil Spill Rates Based on Fault Tree Analysis 

(Bercha Group, 2006)

Spill Source

No. of Spills 

≥ 1,000 bbl

Beaufort Sea OCS Platforms and Wells 0.33 spills/Bbbl 

Beaufort Sea OCS Pipelines 0.20 spills/Bbbl 

Poisson Distribution: The probability of oil spills occurring assumes that spills occur 

independently of each other as a Poisson process. The Poisson process is a statistical 

distribution commonly used to model random events. Using Bayesian techniques, 

Devanney and Stewart (1974) showed that the probability of n oil-spill contacts can be 

described by a negative binomial distribution. Smith et al. (1982), however, noted that 

when actual exposure is much less than historical exposure, as is the case here, the 

negative binomial distribution can be approximated by a Poisson distribution. The Poisson 

distribution has a significant advantage in calculations because it is defined by only one 

parameter, the assumed number of spills. If p(n,i) is the probability of exactly n contacts to 

environmental resource i, then: 

(,) !

n i

i e pni

n

λ λ − ⋅ =

3 
where n is the specific number of spills (0, 1, 2, ..., n), e is the base of the natural 

logarithm, and λ is the parameter of the Poisson distribution. For oil spills, the Poisson 

parameter (λ) is equal to the spill rate multiplied by the volume of oil to be produced or 

transported. The spill rate has dimensions of number of spills/Bbbl, and the volume is 

expressed in Bbbl. Therefore, λ denotes the mean number of spills estimated to occur as a 

result of production or transportation of a specific volume of oil. 

Oil-spill occurrence estimates for spills greater than or equal to 1,000 bbl were calculated 

for production and transportation of oil during the 30-year analysis period associated with 

the proposed actions in the Beaufort Sea OCS Program (2004-2033). These probabilities 

are based on the volume of oil assumed to be found, produced, and transported over the 

production life of the lease and on the rates that have been calculated for oil spills from 

OCS platforms and pipelines by the Bercha Group. The probabilities of one or more oil 

spills greater than or equal to 1,000 bbl occurring as a result of OCS production and 

transportation resulting from the proposed lease sales or deferral area alternatives are found 

in USDOI/MMS (2006: Table C-8). The updated probabilities of one or more large spills 

occurring for Lease Sale 202 are shown in Table R1. 

Discussion 

Tables R20 through R25 and R29 through R31 show the annual combined probabilities for 

the Proposal and the alternatives for Sale 202. The combined probabilities were 

recalculated using the updated spill rates for Sale 202. For the most part, the chance of one 

or more spills occurring and contacting environmental resource areas or land segments is 

less than (<) 0.5 percent within 30 days. The OSRA model estimates a <0.5- to 4-percent 

chance of one or more spills greater than or equal to (≥) 1,000 bbl occurring and contacting 

environmental resources areas, land segments, or land within 30 days, over the production 

life of the Proposed Action. The OSRA model estimates a <0.5- to 5-percent chance of 

one or more spills ≥1,000 bbl occurring and contacting environmental resource areas or 

land segments within 360 days, over the production life of the Proposed Action. The 

OSRA model estimates a 14-percent chance of one or more spills ≥1,000 bbl occurring and 

contacting land within 360 days, over the production life of the Proposed Action. 

Because the combined probabilities are similar to one another, it is difficult to distinguish 

differences between the Proposal and alternatives based on combined probabilities. 

References Cited 

Bercha Group, 2002. Alternative Oil Spill Occurrence Estimators for the Beaufort and 

Chukchi Seas – Fault Tree Method. OCS Study MMS 2002-047. Prepared for 

USDOI/MMS, Alaska OCS Region. Contract No. 01-00-PO-17199. Calgary, 

Alberta, Canada: Bercha International Inc., Bercha Group. August 2002 

4 
Bercha Group. 2006. Alternative Oil Spill Occurrence Estimators and their Variability for 

the Beaufort Sea – Fault Tree Method . OCS Study MMS 2005-061. Prepared for 

USDOI/MMS, Alaska OCS Region. MMS Contract Number 1435-01-04-PO336507. Calgary, Alberta, Canada: Bercha International Inc., Bercha Group. 

January 2006. 

Devanney, M.W., III, and R.J. Stewart. 1974. Analysis of Oilspill Statistics, April 1974. 

Massachusetts Institute of Technology (Cambridge) Report No. MITSG-74-20. 

Prepared for the Council on Environmental Quality. 

Johnson, W.R., C.M. Anderson, C.F. Marshall, and E.M. Lear. 2002. Oil-Spill Risk 

Analysis: Beaufort Sea Planning Area, Sales 186, 195, and 202. OCS Report MMS 

2002-058. Herndon, VA: USDOI/Minerals Management Service, Environmental 

Division. September 2002. 

U.S. Department of the Interior, Minerals Management Service (USDOI/MMS). 2006. 

Environmental Assessment, Proposed OCS Lease Sale 202, Beaufort Sea Planning 

Area. OCS EIS/EA MMS 2006-001. Anchorage, AK: USDOI/MMS, Alaska OCS 

Region. 

5 
Table 1R. Estimated Percent Chance of One or More Large Platform, Pipeline, and Total Spills for Lease 

Sale 202 and Its Alternatives over the Life of the Project 

Alternative 

Percent Chance 

of One or More 

Pipeline Spills 

Percent Chance 

of One or More 

Platform Spills 

Percent Chance 

of One or More 

Spills Total 

I Full Sale Area 9 14 21 

II No Sale 0 0 0 

III Barrow Subsistence Whale Deferral 9 14 21 

IV Nuiqsut Subsistence Whale Deferral 9 13 21 

V Kaktovik Subsistence Whale Deferral 9 14 21 

VI Eastern Deferral 9 14 21 

VII Proposed Action 9 14 21 

6 
Table 20R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain environmental resource over the assumed production life of the 

3 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

E

B

D

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean Prob 

Land 1 0.0 1 0.0 1 0.0 1 0.0 1 Kasegaluk Lagoon n 0.0 n 0.0 n 0.0 n 0.0 n Point Barrow, Plover Islands n 0.0 n 0.0 n 0.0 n 0.0 n Thetis and Jones Islands n 0.0 n 0.0 n 0.0 n 0.0 n Cottle & Return Islands, West Dock n 0.0 n 0.0 n 0.0 n 0.0 n Midway Islands n 0.0 n 0.0 n 0.0 n 0.0 n Cross and No Name Islands n 0.0 n 0.0 n 0.0 n 0.0 n Endicott Causeway n 0.0 n 0.0 n 0.0 n 0.0 n McClure Islands n 0.0 n 0.0 n 0.0 n 0.0 n Stockton Islands n 0.0 n 0.0 n 0.0 n 0.0 n Tigvariak Island n 0.0 n 0.0 n 0.0 n 0.0 n Maguire Islands n 0.0 n 0.0 n 0.0 n 0.0 n Flaxman Island n 0.0 n 0.0 n 0.0 n 0.0 n Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 n Anderson Point Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 n Arey and Barter Islands, Bernard Spit n 0.0 n 0.0 n 0.0 n 0.0 n Jago and Tapkaurak Spits n 0.0 n 0.0 n 0.0 n 0.0 n Angun and Beaufort Lagoons n 0.0 n 0.0 n 0.0 n 0.0 n Icy Reef n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 1 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 2 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 3 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 4 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 5 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 6 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 7 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 8 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 9 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 10 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 1 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 2 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 3 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 4 1 0.0 1 0.0 n 0.0 1 0.0 1 Ice/Sea Segment 5 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 6 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 7 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 8 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 9 n 0.0 n 0.0 n 0.0 n 0.0 n Point Hope Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Point Lay Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Wainwright Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Barrow Subsistence Area 1 n 0.0 n 0.0 n 0.0 n 0.0 n Barrow Subsistence Area 2 n 0.0 n 0.0 n 0.0 n 0.0 n Nuiqsut Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Kaktovik Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Note: ** = Greater than 99.5%; n = Less than 0.5%. 

7
Table 20R (Continued). Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 

estimated number of spills (mean), occurring and contacting a certain environmental resource over the assumed production within 3 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

E

B

D

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean Prob 

Whale Concentration Area n 0.0 n 0.0 n 0.0 n 0.0 n Herald Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 10 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 11 n 0.0 n 0.0 n 0.0 n 0.0 n Hanna's Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 12 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 13 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 14 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 15 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 16a 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 17 2 0.0 2 0.0 1 0.0 2 0.0 2 Ice/Sea Segment 18a 2 0.0 2 0.0 1 0.0 2 0.0 2 Ice/Sea Segment 19 4 0.0 4 0.0 4 0.0 4 0.0 4 Ice/Sea Segment 20a n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 21 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 24a n 0.0 n 0.0 n 0.0 n 0.0 n Ledyard Bay n 0.0 n 0.0 n 0.0 n 0.0 n Peard Bay n 0.0 n 0.0 n 0.0 n 0.0 n ERA 1 1 0.0 1 0.0 1 0.0 1 0.0 1 ERA 2 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 16b 1 0.0 1 0.0 1 0.0 1 0.0 1 Harrison Bay n 0.0 n 0.0 n 0.0 n 0.0 n Harrison Bay/Colville Delta n 0.0 n 0.0 n 0.0 n 0.0 n ERA 3 1 0.0 1 0.0 1 0.0 1 0.0 1 Simpson Lagoon n 0.0 n 0.0 n 0.0 n 0.0 n Gwyder Bay n 0.0 n 0.0 n 0.0 n 0.0 n Prudhoe Bay n 0.0 n 0.0 n 0.0 n 0.0 n Cross Island ERA 1 0.0 1 0.0 n 0.0 1 0.0 1 Water over Boulder Patch 1 n 0.0 n 0.0 n 0.0 n 0.0 n Water over Boulder Patch 2 n 0.0 n 0.0 n 0.0 n 0.0 n Foggy Island Bay n 0.0 n 0.0 n 0.0 n 0.0 n Mikkelsen Bay n 0.0 n 0.0 n 0.0 n 0.0 n ERA 4 1 0.0 1 0.0 n 0.0 1 0.0 1 Ice/Sea Segment 18b 1 0.0 1 0.0 1 0.0 1 0.0 1 Simpson Cove n 0.0 n 0.0 n 0.0 n 0.0 n ERA 5 n 0.0 n 0.0 n 0.0 n 0.0 n Kaktovik ERA 1 0.0 1 0.0 1 0.0 n 0.0 1 Ice/Sea Segment 20b n 0.0 n 0.0 n 0.0 n 0.0 n ERA 6 n 0.0 n 0.0 n 0.0 n 0.0 n ERA 7 n 0.0 n 0.0 n 0.0 n 0.0 n ERA 8 n 0.0 n 0.0 n 0.0 n 0.0 n Ice Sea Segment 24b n 0.0 n 0.0 n 0.0 n 0.0 n Note: ** = Greater than 99.5%; n = Less than 0.5%. 

8
Table 21R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain environmental resource over the assumed production life of the 

Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

E

B

D

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean Prob 

Land 2 0.0 2 0.0 2 0.0 2 0.0 2 Kasegaluk Lagoon n 0.0 n 0.0 n 0.0 n 0.0 n Point Barrow, Plover Islands n 0.0 n 0.0 n 0.0 n 0.0 n Thetis and Jones Islands n 0.0 n 0.0 n 0.0 n 0.0 n Cottle & Return Islands, West Dock n 0.0 n 0.0 n 0.0 n 0.0 n Midway Islands n 0.0 n 0.0 n 0.0 n 0.0 n Cross and No Name Islands n 0.0 n 0.0 n 0.0 n 0.0 n Endicott Causeway n 0.0 n 0.0 n 0.0 n 0.0 n McClure Islands n 0.0 n 0.0 n 0.0 n 0.0 n Stockton Islands n 0.0 n 0.0 n 0.0 n 0.0 n Tigvariak Island n 0.0 n 0.0 n 0.0 n 0.0 n Maguire Islands n 0.0 n 0.0 n 0.0 n 0.0 n Flaxman Island n 0.0 n 0.0 n 0.0 n 0.0 n Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 n Anderson Point Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 n Arey and Barter Islands, Bernard Spit n 0.0 n 0.0 n 0.0 n 0.0 n Jago and Tapkaurak Spits n 0.0 n 0.0 n 0.0 n 0.0 n Angun and Beaufort Lagoons n 0.0 n 0.0 n 0.0 n 0.0 n Icy Reef n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 1 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 2 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 3 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 4 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 5 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 6 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 7 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 8 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 9 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 10 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 1 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 2 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 3 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 4 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 5 1 0.0 1 0.0 n 0.0 1 0.0 1 Ice/Sea Segment 6 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 7 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 8 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 9 n 0.0 n 0.0 n 0.0 n 0.0 n Point Hope Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Point Lay Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Wainwright Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Barrow Subsistence Area 1 n 0.0 n 0.0 n 0.0 n 0.0 n Barrow Subsistence Area 2 n 0.0 n 0.0 n 0.0 n 0.0 n Nuiqsut Subsistence Area 1 0.0 1 0.0 n 0.0 1 0.0 1 Kaktovik Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Note: ** = Greater than 99.5%; n = Less than 0.5%. 

9
Table 21R (Continued). Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 

estimated number of spills (mean), occurring and contacting a certain environmental resource over the assumed production within 10 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

E

B

D

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean Prob 

Whale Concentration Area n 0.0 n 0.0 n 0.0 n 0.0 n Herald Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 10 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 11 n 0.0 n 0.0 n 0.0 n 0.0 n Hanna's Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 12 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 13 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 14 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 15 2 0.0 2 0.0 2 0.0 2 0.0 2 Ice/Sea Segment 16a 2 0.0 2 0.0 2 0.0 2 0.0 2 Ice/Sea Segment 17 3 0.0 3 0.0 2 0.0 3 0.0 3 Ice/Sea Segment 18a 3 0.0 3 0.0 2 0.0 3 0.0 3 Ice/Sea Segment 19 4 0.0 4 0.0 4 0.0 4 0.0 4 Ice/Sea Segment 20a 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 21 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 24a n 0.0 n 0.0 n 0.0 n 0.0 n Ledyard Bay n 0.0 n 0.0 n 0.0 n 0.0 n Peard Bay n 0.0 n 0.0 n 0.0 n 0.0 n ERA 1 1 0.0 1 0.0 1 0.0 1 0.0 1 ERA 2 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 16b 1 0.0 1 0.0 1 0.0 1 0.0 1 Harrison Bay n 0.0 n 0.0 n 0.0 n 0.0 n Harrison Bay/Colville Delta n 0.0 n 0.0 n 0.0 n 0.0 n ERA 3 1 0.0 1 0.0 1 0.0 1 0.0 1 Simpson Lagoon n 0.0 n 0.0 n 0.0 n 0.0 n Gwyder Bay n 0.0 n 0.0 n 0.0 n 0.0 n Prudhoe Bay n 0.0 n 0.0 n 0.0 n 0.0 n Cross Island ERA 1 0.0 1 0.0 1 0.0 1 0.0 1 Water over Boulder Patch 1 n 0.0 n 0.0 n 0.0 n 0.0 n Water over Boulder Patch 2 n 0.0 n 0.0 n 0.0 n 0.0 n Foggy Island Bay n 0.0 n 0.0 n 0.0 n 0.0 n Mikkelsen Bay n 0.0 n 0.0 n 0.0 n 0.0 n ERA 4 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 18b 1 0.0 1 0.0 1 0.0 1 0.0 1 Simpson Cove n 0.0 n 0.0 n 0.0 n 0.0 n ERA 5 1 0.0 1 0.0 1 0.0 1 0.0 1 Kaktovik ERA 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 20b 1 0.0 1 0.0 1 0.0 1 0.0 1 ERA 6 n 0.0 n 0.0 n 0.0 n 0.0 n ERA 7 n 0.0 n 0.0 n 0.0 n 0.0 n ERA 8 n 0.0 n 0.0 n 0.0 n 0.0 n Ice Sea Segment 24b n 0.0 n 0.0 n 0.0 n 0.0 n Note: ** = Greater than 99.5%; n = Less than 0.5%. 

10
Table 22R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain environmental resource over the assumed production life of the 

Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean 

Land 4 0.0 4 0.0 4 0.0 4 0.0 Kasegaluk Lagoon n 0.0 n 0.0 n 0.0 n 0.0 Point Barrow, Plover Islands n 0.0 n 0.0 n 0.0 n 0.0 Thetis and Jones Islands 1 0.0 1 0.0 1 0.0 1 0.0 Cottle & Return Islands, West Dock n 0.0 n 0.0 n 0.0 n 0.0 Midway Islands n 0.0 n 0.0 n 0.0 n 0.0 Cross and No Name Islands n 0.0 n 0.0 n 0.0 n 0.0 Endicott Causeway n 0.0 n 0.0 n 0.0 n 0.0 McClure Islands n 0.0 n 0.0 n 0.0 n 0.0 Stockton Islands n 0.0 n 0.0 n 0.0 n 0.0 Tigvariak Island n 0.0 n 0.0 n 0.0 n 0.0 Maguire Islands n 0.0 n 0.0 n 0.0 n 0.0 Flaxman Island n 0.0 n 0.0 n 0.0 n 0.0 Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 Anderson Point Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 Arey and Barter Islands, Bernard Spit n 0.0 n 0.0 n 0.0 n 0.0 Jago and Tapkaurak Spits n 0.0 n 0.0 n 0.0 n 0.0 Angun and Beaufort Lagoons n 0.0 n 0.0 n 0.0 n 0.0 Icy Reef n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 1 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 2 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 3 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 4 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 5 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 6 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 7 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 8 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 9 1 0.0 1 0.0 1 0.0 1 0.0 Beaufort Spring Lead 10 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 1 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 2 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 3 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 4 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 5 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 6 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 7 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 8 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 9 n 0.0 n 0.0 n 0.0 n 0.0 Point Hope Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Point Lay Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Wainwright Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Barrow Subsistence Area 1 n 0.0 n 0.0 n 0.0 n 0.0 Barrow Subsistence Area 2 1 0.0 1 0.0 1 0.0 1 0.0 Nuiqsut Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 Kaktovik Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

11
Table 22R (Continued). Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 

estimated number of spills (mean), occurring and contacting a certain environmental resource over the assumed production within 30 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean 

Whale Concentration Area n 0.0 n 0.0 n 0.0 n 0.0 Herald Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 10 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 11 n 0.0 n 0.0 n 0.0 n 0.0 Hanna's Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 12 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 13 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 14 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 15 3 0.0 2 0.0 2 0.0 3 0.0 Ice/Sea Segment 16a 3 0.0 3 0.0 3 0.0 3 0.0 Ice/Sea Segment 17 4 0.0 4 0.0 3 0.0 4 0.0 Ice/Sea Segment 18a 3 0.0 3 0.0 2 0.0 3 0.0 Ice/Sea Segment 19 5 0.0 5 0.0 5 0.0 4 0.0 Ice/Sea Segment 20a 2 0.0 2 0.0 2 0.0 2 0.0 Ice/Sea Segment 21 1 0.0 1 0.0 1 0.0 n 0.0 Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 24a n 0.0 n 0.0 n 0.0 n 0.0 Ledyard Bay n 0.0 n 0.0 n 0.0 n 0.0 Peard Bay n 0.0 n 0.0 n 0.0 n 0.0 ERA 1 1 0.0 1 0.0 1 0.0 1 0.0 ERA 2 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 16b 2 0.0 2 0.0 2 0.0 2 0.0 Harrison Bay 1 0.0 1 0.0 1 0.0 1 0.0 Harrison Bay/Colville Delta 1 0.0 1 0.0 1 0.0 1 0.0 ERA 3 2 0.0 2 0.0 2 0.0 2 0.0 Simpson Lagoon 1 0.0 1 0.0 1 0.0 1 0.0 Gwyder Bay n 0.0 n 0.0 n 0.0 n 0.0 Prudhoe Bay n 0.0 n 0.0 n 0.0 n 0.0 Cross Island ERA 1 0.0 1 0.0 1 0.0 1 0.0 Water over Boulder Patch 1 n 0.0 n 0.0 n 0.0 n 0.0 Water over Boulder Patch 2 n 0.0 n 0.0 n 0.0 n 0.0 Foggy Island Bay n 0.0 n 0.0 n 0.0 n 0.0 Mikkelsen Bay n 0.0 n 0.0 n 0.0 n 0.0 ERA 4 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 18b 2 0.0 2 0.0 1 0.0 2 0.0 Simpson Cove n 0.0 n 0.0 n 0.0 n 0.0 ERA 5 1 0.0 1 0.0 1 0.0 1 0.0 Kaktovik ERA 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 20b 1 0.0 1 0.0 1 0.0 1 0.0 ERA 6 n 0.0 n 0.0 n 0.0 n 0.0 ERA 7 n 0.0 n 0.0 n 0.0 n 0.0 ERA 8 n 0.0 n 0.0 n 0.0 n 0.0 Ice Sea Segment 24b n 0.0 n 0.0 n 0.0 n 0.0 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

12
Table 23R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain environmental resource over the assumed production life of the 

60 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean 

Land 6 0.1 6 0.1 6 0.1 6 0.1 Kasegaluk Lagoon n 0.0 n 0.0 n 0.0 n 0.0 Point Barrow, Plover Islands n 0.0 n 0.0 n 0.0 n 0.0 Thetis and Jones Islands 1 0.0 1 0.0 1 0.0 1 0.0 Cottle & Return Islands, West Dock n 0.0 n 0.0 n 0.0 n 0.0 Midway Islands n 0.0 n 0.0 n 0.0 n 0.0 Cross and No Name Islands n 0.0 n 0.0 n 0.0 n 0.0 Endicott Causeway n 0.0 n 0.0 n 0.0 n 0.0 McClure Islands n 0.0 n 0.0 n 0.0 n 0.0 Stockton Islands n 0.0 n 0.0 n 0.0 n 0.0 Tigvariak Island n 0.0 n 0.0 n 0.0 n 0.0 Maguire Islands n 0.0 n 0.0 n 0.0 n 0.0 Flaxman Island n 0.0 n 0.0 n 0.0 n 0.0 Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 Anderson Point Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 Arey and Barter Islands, Bernard Spit n 0.0 n 0.0 n 0.0 n 0.0 Jago and Tapkaurak Spits n 0.0 n 0.0 n 0.0 n 0.0 Angun and Beaufort Lagoons n 0.0 n 0.0 n 0.0 n 0.0 Icy Reef n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 1 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 2 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 3 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 4 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 5 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 6 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 7 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 8 1 0.0 1 0.0 1 0.0 1 0.0 Beaufort Spring Lead 9 1 0.0 1 0.0 1 0.0 1 0.0 Beaufort Spring Lead 10 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 1 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 2 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 3 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 4 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 5 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 6 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 7 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 8 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 9 n 0.0 n 0.0 n 0.0 n 0.0 Point Hope Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Point Lay Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Wainwright Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Barrow Subsistence Area 1 n 0.0 n 0.0 n 0.0 n 0.0 Barrow Subsistence Area 2 1 0.0 1 0.0 1 0.0 1 0.0 Nuiqsut Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 Kaktovik Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

13
Table 23R. (Continued) Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 

estimated number of spills (mean), occurring and contacting a certain environmental resource over the assumed production within 60 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean 

Whale Concentration Area n 0.0 n 0.0 n 0.0 n 0.0 Herald Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 10 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 11 n 0.0 n 0.0 n 0.0 n 0.0 Hanna's Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 12 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 13 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 14 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 15 3 0.0 3 0.0 3 0.0 3 0.0 Ice/Sea Segment 16a 4 0.0 4 0.0 4 0.0 4 0.0 Ice/Sea Segment 17 4 0.0 4 0.0 4 0.0 4 0.0 Ice/Sea Segment 18a 3 0.0 3 0.0 3 0.0 3 0.0 Ice/Sea Segment 19 5 0.0 5 0.0 5 0.0 5 0.0 Ice/Sea Segment 20a 2 0.0 2 0.0 2 0.0 2 0.0 Ice/Sea Segment 21 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 22 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 24a n 0.0 n 0.0 n 0.0 n 0.0 Ledyard Bay n 0.0 n 0.0 n 0.0 n 0.0 Peard Bay n 0.0 n 0.0 n 0.0 n 0.0 ERA 1 1 0.0 1 0.0 1 0.0 1 0.0 ERA 2 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 16b 2 0.0 2 0.0 2 0.0 2 0.0 Harrison Bay 1 0.0 1 0.0 1 0.0 1 0.0 Harrison Bay/Colville Delta 1 0.0 1 0.0 1 0.0 1 0.0 ERA 3 2 0.0 2 0.0 2 0.0 2 0.0 Simpson Lagoon 1 0.0 1 0.0 1 0.0 1 0.0 Gwyder Bay n 0.0 n 0.0 n 0.0 n 0.0 Prudhoe Bay n 0.0 n 0.0 n 0.0 n 0.0 Cross Island ERA 1 0.0 1 0.0 1 0.0 1 0.0 Water over Boulder Patch 1 n 0.0 n 0.0 n 0.0 n 0.0 Water over Boulder Patch 2 n 0.0 n 0.0 n 0.0 n 0.0 Foggy Island Bay n 0.0 n 0.0 n 0.0 n 0.0 Mikkelsen Bay n 0.0 n 0.0 n 0.0 n 0.0 ERA 4 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 18b 2 0.0 2 0.0 1 0.0 2 0.0 Simpson Cove n 0.0 n 0.0 n 0.0 n 0.0 ERA 5 1 0.0 1 0.0 1 0.0 1 0.0 Kaktovik ERA 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 20b 1 0.0 1 0.0 1 0.0 1 0.0 ERA 6 n 0.0 n 0.0 n 0.0 n 0.0 ERA 7 n 0.0 n 0.0 n 0.0 n 0.0 ERA 8 n 0.0 n 0.0 n 0.0 n 0.0 Ice Sea Segment 24b n 0.0 n 0.0 n 0.0 n 0.0 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

14
Table 24R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain environmental resource over the assumed production life of the 

180 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean P

Land 10 0.1 10 0.1 10 0.1 10 0.1 Kasegaluk Lagoon n 0.0 n 0.0 n 0.0 n 0.0 Point Barrow, Plover Islands 1 0.0 1 0.0 1 0.0 1 0.0 Thetis and Jones Islands 2 0.0 2 0.0 1 0.0 2 0.0 Cottle & Return Islands, West Dock 1 0.0 1 0.0 1 0.0 1 0.0 Midway Islands n 0.0 n 0.0 n 0.0 n 0.0 Cross and No Name Islands n 0.0 n 0.0 n 0.0 n 0.0 Endicott Causeway n 0.0 n 0.0 n 0.0 n 0.0 McClure Islands n 0.0 n 0.0 n 0.0 n 0.0 Stockton Islands n 0.0 n 0.0 n 0.0 n 0.0 Tigvariak Island n 0.0 n 0.0 n 0.0 n 0.0 Maguire Islands n 0.0 n 0.0 n 0.0 n 0.0 Flaxman Island n 0.0 n 0.0 n 0.0 n 0.0 Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 Anderson Point Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 Arey and Barter Islands, Bernard Spit 1 0.0 1 0.0 1 0.0 1 0.0 Jago and Tapkaurak Spits 1 0.0 1 0.0 1 0.0 1 0.0 Angun and Beaufort Lagoons n 0.0 n 0.0 n 0.0 n 0.0 Icy Reef n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 1 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 2 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 3 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 4 n 0.0 n 0.0 n 0.0 n 0.0 Chukchi Spring Lead 5 n 0.0 n 0.0 n 0.0 n 0.0 Beaufort Spring Lead 6 1 0.0 1 0.0 1 0.0 1 0.0 Beaufort Spring Lead 7 1 0.0 1 0.0 1 0.0 1 0.0 Beaufort Spring Lead 8 1 0.0 1 0.0 1 0.0 1 0.0 Beaufort Spring Lead 9 1 0.0 1 0.0 1 0.0 1 0.0 Beaufort Spring Lead 10 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 1 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 2 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 3 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 4 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 5 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 6 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 7 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 8 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 9 n 0.0 n 0.0 n 0.0 n 0.0 Point Hope Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Point Lay Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Wainwright Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 Barrow Subsistence Area 1 n 0.0 n 0.0 n 0.0 n 0.0 Barrow Subsistence Area 2 1 0.0 1 0.0 1 0.0 1 0.0 Nuiqsut Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 Kaktovik Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

15
Table 24R (Continued). Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 

estimated number of spills (mean), occurring and contacting a certain environmental resource over the assumed production within 180 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean P

Whale Concentration Area n 0.0 n 0.0 n 0.0 n 0.0 Herald Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 10 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 11 n 0.0 n 0.0 n 0.0 n 0.0 Hanna's Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 12 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 13 n 0.0 n 0.0 n 0.0 n 0.0 Ice/Sea Segment 14 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 15 4 0.0 4 0.0 4 0.0 4 0.0 Ice/Sea Segment 16a 5 0.1 5 0.1 5 0.0 5 0.1 Ice/Sea Segment 17 5 0.0 5 0.0 4 0.0 5 0.0 Ice/Sea Segment 18a 4 0.0 4 0.0 3 0.0 4 0.0 Ice/Sea Segment 19 5 0.1 5 0.1 5 0.1 5 0.1 Ice/Sea Segment 20a 3 0.0 3 0.0 3 0.0 3 0.0 Ice/Sea Segment 21 2 0.0 2 0.0 1 0.0 1 0.0 Ice/Sea Segment 22 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 22 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 24a n 0.0 n 0.0 n 0.0 n 0.0 Ledyard Bay n 0.0 n 0.0 n 0.0 n 0.0 Peard Bay n 0.0 n 0.0 n 0.0 n 0.0 ERA 1 2 0.0 2 0.0 2 0.0 2 0.0 ERA 2 2 0.0 2 0.0 2 0.0 2 0.0 Ice/Sea Segment 16b 3 0.0 3 0.0 3 0.0 3 0.0 Harrison Bay 1 0.0 1 0.0 1 0.0 1 0.0 Harrison Bay/Colville Delta 1 0.0 1 0.0 1 0.0 1 0.0 ERA 3 3 0.0 3 0.0 3 0.0 3 0.0 Simpson Lagoon 1 0.0 1 0.0 1 0.0 1 0.0 Gwyder Bay n 0.0 n 0.0 n 0.0 n 0.0 Prudhoe Bay n 0.0 n 0.0 n 0.0 n 0.0 Cross Island ERA 2 0.0 2 0.0 1 0.0 2 0.0 Water over Boulder Patch 1 1 0.0 1 0.0 n 0.0 1 0.0 Water over Boulder Patch 2 1 0.0 1 0.0 1 0.0 1 0.0 Foggy Island Bay n 0.0 n 0.0 n 0.0 n 0.0 Mikkelsen Bay n 0.0 n 0.0 n 0.0 n 0.0 ERA 4 1 0.0 1 0.0 1 0.0 1 0.0 Ice/Sea Segment 18b 2 0.0 2 0.0 2 0.0 2 0.0 Simpson Cove n 0.0 n 0.0 n 0.0 n 0.0 ERA 5 1 0.0 1 0.0 1 0.0 1 0.0 Kaktovik ERA 2 0.0 2 0.0 2 0.0 2 0.0 Ice/Sea Segment 20b 2 0.0 2 0.0 2 0.0 2 0.0 ERA 6 1 0.0 1 0.0 1 0.0 1 0.0 ERA 7 n 0.0 n 0.0 n 0.0 n 0.0 ERA 8 n 0.0 n 0.0 n 0.0 n 0.0 Ice Sea Segment 24b n 0.0 n 0.0 n 0.0 n 0.0 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

16
Table 25R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain environmental resource over the assumed production life of the 

360 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

E

Bo

D

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean Prob 

Land 14 0.2 14 0.2 14 0.1 14 0.1 14 Kasegaluk Lagoon n 0.0 n 0.0 n 0.0 n 0.0 n Point Barrow, Plover Islands 1 0.0 1 0.0 1 0.0 1 0.0 1 Thetis and Jones Islands 2 0.0 2 0.0 2 0.0 2 0.0 2 Cottle & Return Islands, West Dock 1 0.0 1 0.0 1 0.0 1 0.0 1 Midway Islands n 0.0 n 0.0 n 0.0 n 0.0 n Cross and No Name Islands 1 0.0 1 0.0 n 0.0 1 0.0 1 Endicott Causeway n 0.0 n 0.0 n 0.0 n 0.0 n McClure Islands 1 0.0 1 0.0 n 0.0 1 0.0 1 Stockton Islands n 0.0 n 0.0 n 0.0 n 0.0 n Tigvariak Island n 0.0 n 0.0 n 0.0 n 0.0 n Maguire Islands n 0.0 n 0.0 n 0.0 n 0.0 n Flaxman Island n 0.0 n 0.0 n 0.0 n 0.0 n Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 n Anderson Point Barrier Islands n 0.0 n 0.0 n 0.0 n 0.0 n Arey and Barter Islands, Bernard Spit 1 0.0 1 0.0 1 0.0 1 0.0 1 Jago and Tapkaurak Spits 1 0.0 1 0.0 1 0.0 1 0.0 1 Angun and Beaufort Lagoons n 0.0 n 0.0 n 0.0 n 0.0 n Icy Reef n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 1 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 2 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 3 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 4 n 0.0 n 0.0 n 0.0 n 0.0 n Chukchi Spring Lead 5 n 0.0 n 0.0 n 0.0 n 0.0 n Beaufort Spring Lead 6 1 0.0 1 0.0 1 0.0 1 0.0 1 Beaufort Spring Lead 7 1 0.0 1 0.0 1 0.0 1 0.0 1 Beaufort Spring Lead 8 1 0.0 1 0.0 1 0.0 1 0.0 1 Beaufort Spring Lead 9 1 0.0 1 0.0 1 0.0 1 0.0 1 Beaufort Spring Lead 10 2 0.0 2 0.0 2 0.0 2 0.0 2 Ice/Sea Segment 1 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 2 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 3 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 4 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 5 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 6 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 7 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 8 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 9 n 0.0 n 0.0 n 0.0 n 0.0 n Point Hope Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Point Lay Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Wainwright Subsistence Area n 0.0 n 0.0 n 0.0 n 0.0 n Barrow Subsistence Area 1 n 0.0 n 0.0 n 0.0 n 0.0 n Barrow Subsistence Area 2 1 0.0 1 0.0 1 0.0 1 0.0 1 Nuiqsut Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 1 Kaktovik Subsistence Area 1 0.0 1 0.0 1 0.0 1 0.0 1 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

17
Table 25R (Continued). Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 

estimated number of spills (mean), occurring and contacting a certain environmental resource over the assumed production within 360 days, Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

E

Bo

D

Environmental 

Resource Prob Mean Prob Mean Prob Mean Prob Mean Prob 

Whale Concentration Area n 0.0 n 0.0 n 0.0 n 0.0 n Herald Shoal Polynya n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 10 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 11 n 0.0 n 0.0 n 0.0 n 0.0 n Hanna's Shoal Polynya 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 12 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 13 n 0.0 n 0.0 n 0.0 n 0.0 n Ice/Sea Segment 14 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 15 4 0.0 4 0.0 4 0.0 4 0.0 4 Ice/Sea Segment 16a 5 0.1 5 0.1 5 0.1 5 0.1 5 Ice/Sea Segment 17 5 0.1 5 0.1 5 0.0 5 0.1 5 Ice/Sea Segment 18a 4 0.0 4 0.0 3 0.0 4 0.0 4 Ice/Sea Segment 19 5 0.1 5 0.1 5 0.1 5 0.1 5 Ice/Sea Segment 20a 4 0.0 4 0.0 4 0.0 3 0.0 3 Ice/Sea Segment 21 2 0.0 2 0.0 2 0.0 2 0.0 2 Ice/Sea Segment 22 2 0.0 2 0.0 2 0.0 2 0.0 2 Ice/Sea Segment 22 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 24a 1 0.0 1 0.0 1 0.0 1 0.0 1 Ledyard Bay n 0.0 n 0.0 n 0.0 n 0.0 n Peard Bay n 0.0 n 0.0 n 0.0 n 0.0 n ERA 1 2 0.0 2 0.0 2 0.0 2 0.0 2 ERA 2 3 0.0 3 0.0 3 0.0 3 0.0 3 Ice/Sea Segment 16b 4 0.0 4 0.0 4 0.0 4 0.0 4 Harrison Bay 1 0.0 1 0.0 1 0.0 1 0.0 1 Harrison Bay/Colville Delta 2 0.0 2 0.0 2 0.0 2 0.0 2 ERA 3 4 0.0 4 0.0 3 0.0 4 0.0 4 Simpson Lagoon 2 0.0 2 0.0 2 0.0 2 0.0 2 Gwyder Bay n 0.0 n 0.0 n 0.0 n 0.0 n Prudhoe Bay n 0.0 n 0.0 n 0.0 n 0.0 n Cross Island ERA 2 0.0 2 0.0 1 0.0 2 0.0 2 Water over Boulder Patch 1 1 0.0 1 0.0 1 0.0 1 0.0 1 Water over Boulder Patch 2 1 0.0 1 0.0 1 0.0 1 0.0 1 Foggy Island Bay 1 0.0 1 0.0 n 0.0 1 0.0 1 Mikkelsen Bay n 0.0 n 0.0 n 0.0 n 0.0 n ERA 4 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice/Sea Segment 18b 2 0.0 2 0.0 2 0.0 2 0.0 2 Simpson Cove n 0.0 n 0.0 n 0.0 n 0.0 n ERA 5 1 0.0 1 0.0 1 0.0 1 0.0 1 Kaktovik ERA 2 0.0 2 0.0 2 0.0 2 0.0 2 Ice/Sea Segment 20b 2 0.0 2 0.0 2 0.0 2 0.0 2 ERA 6 1 0.0 1 0.0 1 0.0 1 0.0 1 ERA 7 1 0.0 1 0.0 1 0.0 1 0.0 1 ERA 8 1 0.0 1 0.0 1 0.0 1 0.0 1 Ice Sea Segment 24b 1 0.0 1 0.0 1 0.0 1 0.0 1 Note: ** = Greater than 99.5%; n = Less than 0.5%. 

18
Table 29R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain land segment over the assumed production life of the lease area 

Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Eastern 

Bowhead 

Deferral 

Land 

Segment Prob Mean Prob Mean Prob Mean Prob Mean Prob Me

32 1 0.0 1 0.0 1 0.0 1 0.0 1 0.

Note: ** = Greater than 99.5%; n = less than 0.5%. Segments with less than 0.5 percent probability of one or more contacts within 60 days are not shown. Table 30R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain land segment over the assumed production life of the lease area 

Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Eastern 

Bowhead 

Deferral 

Land 

Segment Prob Mean Prob Mean Prob Mean Prob Mean Prob Me

25 1 0.0 n 0.0 n 0.0 1 0.0 1 0.28 1 0.0 1 0.0 1 0.0 1 0.0 1 0.31 1 0.0 1 0.0 1 0.0 1 0.0 1 0.32 1 0.0 1 0.0 1 0.0 1 0.0 1 0.36 1 0.0 1 0.0 n 0.0 1 0.0 1 0.47 1 0.0 1 0.0 1 0.0 n 0.0 1 0.

Note: ** = Greater than 99.5%; n = less than 0.5%. Segments with less than 0.5 percent probability of one or more contacts within 180 days are not shown. Table 31R. Combined probabilities (expressed as percent chance) of one or more spills greater than or equal to 1,000 barre

number of spills (mean), occurring and contacting a certain land segment over the assumed production life of the lease area 

Beaufort Sale 202. 

Full 

Sale Area 

Barrow 

Subsistence 

Deferral 

Nuiqsut 

Subsistence 

Deferral 

Kaktovik 

Subsistence 

Deferral 

Eastern 

Bowhead 

Deferral 

Land 

Segment Prob Mean Prob Mean Prob Mean Prob Mean Prob Me

25 1 0.0 1 0.0 1 0.0 1 0.0 1 0.28 1 0.0 1 0.0 1 0.0 1 0.0 1 0.30 1 0.0 1 0.0 1 0.0 1 0.0 1 0.31 1 0.0 1 0.0 1 0.0 1 0.0 1 0.32 1 0.0 1 0.0 1 0.0 1 0.0 1 0.35 1 0.0 1 0.0 1 0.0 1 0.0 1 0.36 1 0.0 1 0.0 1 0.0 1 0.0 1 0.37 1 0.0 1 0.0 1 0.0 1 0.0 1 0.47 1 0.0 1 0.0 1 0.0 1 0.0 1 0.

Note: ** = Greater than 99.5%; n = less than 0.5%. Segments with less than 0.5 percent probability of one or more contacts within 360days are not shown. 

19

The Department of the Interior Mission

As the Nation's principal conservation agency, the Department of the Interior has responsibility 

for most of our nationally owned public lands and natural resources. This includes fostering 

sound use of our land and water resources; protecting our fish, wildlife, and biological diversity; 

preserving the environmental and cultural values of our national parks and historical places; 

and providing for the enjoyment of life through outdoor recreation. The Department assesses 

our energy and mineral resources and works to ensure that their development is in the best 

interests of all our people by encouraging stewardship and citizen participation in their care. 

The Department also has a major responsibility for American Indian reservation communities 

and for people who live in island territories under U.S. administration. 

The Minerals Management Service Mission 

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) 

primary responsibilities are to manage the mineral resources located on the Nation's Outer 

Continental Shelf (OCS), collect revenue from the Federal OCS and onshore Federal and Indian 

lands, and distribute those revenues. 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program 

administers the OCS competitive leasing program and oversees the safe and environmentally 

sound exploration and production of our Nation's offshore natural gas, oil and other mineral 

resources. The MMS Minerals Revenue Management meets its responsibilities by ensuring the 

efficient, timely and accurate collection and disbursement of revenue from mineral leasing and 

production due to Indian tribes and allottees, States and the U.S. Treasury. 

The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially 

affected parties and (2) carrying out its programs with an emphasis on working to enhance the 

quality of life for all Americans by lending MMS assistance and expertise to economic 

development and environmental protection.