CHAPTER 4

Environmental Consequences

4-1 

CHAPTER 4: ENVIRONMENTAL CONSEQUENCES

Introduction

This chapter presents the environmental impacts from 

management actions described in Chapter 2. The 

descriptions of predicted effects that would result from 

the exploration, construction, operation and 

maintenance and abandonment activities associated

with coal bed natural gas (CBNG) for each alternative 

is compared to the pre-project environment. 

Chapter 4 contains an Introduction, Analysis 

Assumptions and Guidelines section and individual 

Resource Topic discussions. Table 2-3, in Chapter 2, 

summarizes and compares the impacts of the 

alternatives. The Introduction outlines the chapter and 

provides an explanation of the organization and 

creation of assumptions. The Analysis Assumptions and 

Guidelines section presents the Reasonably 

Foreseeable Development scenario (RFD) used to 

predict the level of CBNG development and addresses 

the analysis assumptions common to all alternatives. 

The Resource Topic discussions are organized 

alphabetically. Under each resource topic, the 

following are addressed: assumptions, impacts from 

management common to all alternatives and impacts 

from management specific to each alternative.

The duration of the impacts are analyzed and described 

as either short-term (up to 5 years) or long-term 

(greater than 5 years). Impacts from management of 

conventional oil and gas are found in the Impacts from 

Management Common to All Alternatives sections. 

Impacts from management of CBNG are found in the 

Impacts From Management Specific to Each 

Alternative sections.

The narrative describing the impacts from management 

specific to each alternative includes subsections 

summarizing the impacts to the Crow and Northern 

Cheyenne tribes, mitigation measures and a 

conclusions summary. The conclusion summarizes the 

cumulative impacts from other regional ongoing and 

foreseen projects.

Cumulative impacts consider the alternative in 

combination with other substantial existing and future 

developments in and near the Final Supplement to the 

Montana Statewide Oil and Gas Environmental Impact 

Statement and Proposed Amendment of the Powder 

River and Billings Resource Management Plans 

(FSEIS) Planning Area, including oil and gas 

development projects, existing and future coal mines, 

new power plants, the Tongue River Railroad (TRR)

and effects from Wyoming’s CBNG development. 

Project descriptions for activities considered in the 

cumulative impacts analysis are presented in the 

Minerals Appendix under Oil and Gas. Mitigation 

measures that are not already included as part of the 

alternatives are described and evaluated and the 

residual impacts are determined.

The resource discussions also address the differences 

between U.S. Bureau of Land Management (BLM) and 

State of Montana (state) impacts where divisions are 

meaningful. Physical impacts on landscapes from 

development disturbances can easily be quantified for 

Bureau of Land Management (BLM) and state 

regulated wells; however, effects on watersheds or 

wildlife from both BLM and state development cannot 

easily be distinguished and therefore are discussed in 

conjunction.

Analysis Assumptions and 

Guidelines

Analysis assumptions and guidelines provide common 

data to EIS team members to use when conducting the 

impact assessments for each resource. The assumptions 

and guidelines are based on previous events, 

experience of personnel and their knowledge of the 

resources in the Planning Area. The assumptions 

include the demand for various resources, the ability of 

the resources to meet the demand and how the actions 

will be carried out. An RFD was developed for this 

purpose and is discussed in the following sections.

Potential for Development—

Reasonably Foreseeable 

Development Scenarios 

The RFD addresses potential development on all lands, 

including the Crow and Northern Cheyenne

reservations and the Ashland Ranger District of the 

U.S. Forest Service (USFS).

What has Changed in Chapter 4 Since 

the Draft SEIS (DSEIS)? 

The impact analyses from the air quality and wildlife screens 

for Alternative H—Preferred Alternative were altered. The Air

Quality and Climate section has additional changes, such as 

cumulative effects analysis from oil and gas development on 

climate change and also based on the completion of the 

supplemental air quality analysis (SAQA, BLM 2007). 
CHAPTER 4

Environmental Consequences

4-2 

The RFD is in no way stating that the BLM is making 

decisions for Indian lands or the USFS administered 

lands. For example, the decision to develop CBNG on 

Indian lands will be made by the Indian allottees and 

the tribes with concurrence of the Bureau of Indian 

Affairs (BIA), not by BLM. 

The presumption of possible impacts to the 

environment is based on BLM guidance (BLM 

H-1624-1) provided for estimating the potential for oil 

and gas resources and for extrapolating the degree of 

development that is reasonably foreseeable over a 

given period of time. In the case of Montana’s Powder 

River Basin and additional areas within the Billings 

and Powder River RMP areas, it is the level of CBNG

development most likely to occur over the next 20-year 

period. The RFD is located in the Minerals Appendix, 

under “Reasonably Foreseeable Development 

Scenario”. The following sections contain explanations 

of 1) the potential for CBNG resources within the 

Planning Area boundaries and 2) RFD for the different 

detailed development scenarios that are addressed by 

the various alternatives in this FSEIS. 

Potential for CBNG Resources

An estimate of CBNG and conventional oil and gas 

resources was accomplished using many sources of 

information, including established files and databases, 

the BLM Resource Management Plans (RMPs) for the 

areas, coal information from the U.S. Geological 

Survey (USGS), professional and academic literature, 

available oil and gas maps, previous mineral 

assessments and expressions of interest and projections 

from the oil and gas industry. To project CBNG

exploration and development, the areal extent of 

certain coals and the rank of coals in the CBNG

emphasis area were considered. 

Areas of subbituminous to bituminous coals were 

considered as the most likely to be explored and 

developed in Montana, although exploration and 

development has occurred mainly in subbituminous 

coal in the Wyoming portion of the Powder River 

Basin. The USGS produced an Open File Report (OF 

96-92) showing the areas of coal, by rank, for the 

United States. This information indicates 

subbituminous and bituminous coals in many parts of 

the emphasis area. See Map MIN-1 in the Minerals 

Appendix for an illustration of this data and Map 4-1 

for a geographical presentation of potential CBNG

development within Montana. 

Powder River, Rosebud, Custer and Big Horn counties 

contain the northern part of the Powder River Basin, 

which extends from Wyoming. Musselshell County has 

mostly subbituminous coal, while Carbon County has 

an extension of the Big Horn Basin coal, which is 

ranked as bituminous coal. 

The amount of natural gas that could be produced from 

the coal beds in Montana has been projected to range 

from a low of 1 trillion cubic feet (TCF) (Crockett and 

Meyer 2001) to a high of 17.7 TCF (Nelson 2000). 

This and other information for Montana is used to 

predict where CBNG exploration is most likely to 

occur in the RMP areas. The RFD predicts the number 

of CBNG wells that would be drilled and completed 

during the next 20 years per alternative. By making 

these predictions, cumulative impacts can be assessed.

Reasonably Foreseeable 

Development Scenario

Projections of future CBNG development and 

production are difficult to make. Several variables 

complicate such forecasts, including new exploration, 

development or production techniques; increases or 

decreases in demand for natural gas; and price 

increases or decreases that may prompt larger or 

smaller development and production programs. For this 

FSEIS, a combination of historical trends, present 

activity, government and industry estimates and

professional judgments were used in establishing the 

estimate of RFD. The RFD is discussed under three

scenarios: restricted development, expanded

development and phased development. 

Restricted Development

Restricted development is applied to Alternative A. 

Under this scenario, the BLM would only approve 

exploration well permits and the state would only 

proceed with the development identified in the 

Stipulation and Settlement Agreement as presented in 

Chapter 2. With regards to the BLM exploration wells, 

an RFD of 200 wells per RMP area was assigned to 

provide a level of quantification for analysis; however, 

the BLM has no actual upper cap on issuing 

exploration well permits. The RFD numbers in no way 

represents a regulatory number for exploration wells 

that could be issued by the BLM.
4-3 
CHAPTER 4

Environmental Consequences

4-4 

Expanded Development

Expanded development is considered for Alternatives 

B, C, D and E. Expanded refers to the number of 

potential wells based on known coal volumes that 

would be drilled in the RMP areas during the next 20 

years, regardless of mineral ownership. Given the 

current oil and gas stipulations, the restricted 

development areas and the unknown geographical 

distribution of coal bed natural gas, it is unlikely that 

the maximum well density of 1 well per producing coal 

seam per 80 acres would be achieved. Map 4-1 

indicates the predicted number of wells per county 

overlying known coal occurrences. The estimate for 

expanded development ranges from 10,000 to 

26,000 wells drilled, the upper limit includes the 

reasonably foreseeable future activity (RFFA) 

estimates of 4,000 wells each for the Crow and 

Northern Cheyenne reservations and 200 wells for the 

Custer National Forest. The Powder River RMP area 

could host as many as 7,500 to 14,000 producing 

CBNG wells during the next 20 years. The RFD also 

estimated that 200 to 800 new conventional oil and gas 

wells could be drilled in the Powder River RMP area 

during the same time period. In the Billings RMP area, 

an estimated 1,000 to 2,400 producing CBNG wells 

could be installed. Conventional oil and gas wells are 

estimated to increase by 250 to 975 during this same 

time. 

The expanded development estimate also predicted the 

number of potential field and sales compressors needed 

to export the gas. This level of development would 

require from 400 to 1,000 field compressors and from 

50 to 100 sales compressors. Estimates for the 

gathering and sales lines are also included in the RFD.

Phased Development

Phased development of CBNG resources on federal 

leases is analyzed in three alternatives. Alternatives F 

and G describe high and low ranges for phased 

development of federal CBNG, while Alternative H 

(discussed in the following section) is the preferred 

alternative for phased development. The three 

alternatives also address cumulative impacts from the 

phased development of federal CBNG. Phased 

development differs from the expanded (full-field) 

development scenario because BLM would limit the 

number of approved federal Applications for Permit to 

Drill (APDs) by year and by geographic area. 

Alternative F would incorporate a limit based on the 

high range of development predicted within the RFD

and Alternative G would incorporate a limit based on 

the low range of development predicted within the 

RFD. These two phased-development alternatives 

would consider wells per watershed instead of wells 

per county (Tables 4-1 and 4-2). The same high range

predicted total number of potential state, private and

federal wells based on known coal volumes that would 

be drilled under expanded development over the next 

20 years, regardless of mineral ownership, would still 

apply to Alternative F. The constraints (multiple 

screens) imposed under the phased-development 

alternatives would limit the number of BLM-issued 

annual APDs to 5 percent of the total issued (RFD 

scenario rate of development). The projected rate of 

development identified in the RFD will be applied to 

state-approved APDs during the next 20 years. The 

resulting development rate for state wells was used to 

identify the pace at which BLM APDs could be 

approved within the 5 percent constraint. The assumed 

phased development rate for Alternatives F and G is 

shown in Tables 4-3 and 4-4. Figures 4-1 and 4-1A 

show the assumed development rates for Alternatives F 

and G. 

Coal reserves indicate that 15 watersheds may be 

developed for CBNG over the next 20 years. Of these 

15 watersheds, five hold most of the CBNG potential 

in Montana. These five watersheds are all located in 

the Powder River Basin (PRB). 

The watershed screen is a combination of the RFD rate 

of development as applied to the CBNG wells 

approved by the state and an assumed 5 percent limit 

applied to federal wells. The use of this screen has 

resulted in the predicted number of APDs to be issued 

per watershed per year. The assumed order of 

watershed development was determined by proximity 

to existing development (southern watersheds within 

the PRB portion of Montana), operator plans of 

development (PODs) being prepared or being reviewed 

by an agency (see Figure 3-4 and 3-5) and areas with 

multiple coal seams. 

Applying the 5 percent annual screen and the 

watershed screen increases the predicted 20-year 

development period by three years. For years 12

through 23, BLM would not issue the total 5 percent of 

APDs anticipated because the watershed screen would 

influence development. 

Estimates for the total number of compressors needed 

to export the gas are the same as predicted in the RFD 

for each RMP area under Alternative F. Under 

Alternative G, however, the number of compressors 

needed would be 65 percent fewer than the amount 

proposed in the RFD. 
CHAPTER 4

Environmental Consequences 

4-5 

TABLE 4-1

PREDICTED APDS/WATERSHED UNDER ALTERNATIVE F

HIGH-RANGE, PHASED CBNG DEVELOPMENT

 Watershed Name State BLM Total

1 Clarks Fork Yellowstone 233 217 450

2 Little Bighorn 675 0 675

3 Little Powder 104 96 200

4 Lower Bighorn 414 386 800

5 Lower Tongue 1,786 1,664 3,450

6 Lower Yellowstone-Sunday 880 820 1700

7 Middle Musselshell 52 48 100

8 Middle Powder 1,087 1,013 2,100

9 Mizpah 65 60 125

10 Rosebud 1,863 1,737 3,600

11 Stillwater 52 48 100

12 Upper Musselshell 39 36 75

13 Upper Tongue 1,993 1,857 3,850

14 Upper Yellowstone-Lake Basin 414 386 800

15 Upper Yellowstone-Pompeys Pillar 104 96 200

 Total Predicted APDs 9,759 8,466 18,225

TABLE 4-2

PREDICTED APDS/WATERSHED UNDER ALTERNATIVE G

LOW-RANGE, PHASED CBNG DEVELOPMENT

 Watershed Name State BLM Total

1 Clarks Fork Yellowstone 88 82 170

2 Little Bighorn 240 0 240

3 Little Powder 36 34 70

4 Lower Bighorn 145 135 280

5 Lower Tongue 626 584 1,210

6 Lower Yellowstone-Sunday 311 289 600

7 Middle Musselshell 21 19 40

8 Middle Powder 383 357 740

9 Mizpah 21 19 40

10 Rosebud 657 613 1,270

11 Stillwater 21 19 40

12 Upper Musselshell 16 14 30

13 Upper Tongue 699 651 1,350

14 Upper Yellowstone-Lake Basin 155 145 300

15 Upper Yellowstone-Pompeys Pillar 47 43 90

 Total Predicted APDs 3,464 3,006 6,470
CHAPTER 4

Environmental Consequences

4-6 

TABLE 4-3 

ALTERNATIVE F ASSUMED DEVELOPMENT RATE (APDS) 

Year Percentage State/Private BLM Total Annual

1 3% 488 119 607

2 5% 586 324 910

3 6% 1,074 0 1,074

4 6% 1,170 0 1,170

5 6% 1,074 0 1,074

6 5% 781 129 910

7 5% 683 227 910

8 5% 488 422 910

9 5% 488 422 910

10 5% 390 520 910

11 5% 293 617 910

12 5% 293 613 906

13 5% 293 531 824

14 5% 293 531 824

15 5% 293 531 824

16 4% 244 460 704

17 4% 244 459 703

18 4% 244 410 654

19 3% 195 348 543

20 2% 145 299 444

21 3% 0 509 509

22 3% 0 496 496

23 3% 0 499 499

100% 9,759 8,466 18,225

Low-end Total* 8,974 6,918 15,892

*Low-end total reflects the reduction of wells if no drilling occurs within the crucial sage habitat areas on both private and federal mineral estates.

FIGURE 4-1 

ALTERNATIVE F ASSUMED DEVELOPMENT RATE

APDs per Year in the

Montana Portion of the PRB

0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25

Year of RFD

APDs

State/Private

BLM

Cumulative
CHAPTER 4

Environmental Consequences 

4-7 

APDs per Year in the

Montana Portion of the PRB

0

50

100

150

200

250

300

350

400

450

0 5 10 15 20 25

Year of RFD

APDs

State/Fee

BLM

Cumulative

TABLE 4-4

ALTERNATIVE G ASSUMED DEVELOPMENT RATE (APDS)

Year Percentage State/Private BLM Total Annual

1 3% 173 42 215

2 5% 208 115 323

3 6% 381 0 381

4 6% 416 0 416

5 6% 382 0 382

6 5% 277 46 323

7 5% 242 81 323

8 5% 173 150 323

9 5% 173 150 323

10 5% 138 185 323

11 5% 104 217 321

12 5% 104 217 321 

13 5% 104 189 293

14 5% 104 189 293

15 5% 104 188 292

16 4% 87 163 250

17 4% 87 163 250

18 4% 87 146 233

19 3% 69 124 193

20 2% 51 106 157

21 3% 0 181 181

22 3% 0 176 176

23 3% 0 177 177

100% 3,464 3,006 6,470

FIGURE 4-1A 

ALTERNATIVE G ASSUMED DEVELOPMENT RATE

● State/Private

■ BLM

▲ Cumulative
CHAPTER 4

Environmental Consequences

4-8 

Preferred Alternative Development

Development anticipated under Preferred Alternative H 

might differ slightly from the high-range, phased 

development scenario (Alternative F). The cumulative 

number of APDs per year would be similar; however, 

BLM could approve APDs each year and would not be 

restricted by the number of CBNG permits approved 

by the state. During the initial 5-year development 

period, BLM could issue APDs for federally

administered minerals at a rate similar to permits

issued by the state for private and state administered 

minerals. Furthermore, since BLM could issue APDs 

each year, the development scenario duration might be 

somewhat shorter than Alternative F at 23 years. The 

rate of development for approved state/private wells 

under the preferred alternative would be lower than 

predicted under the RFD. This is based on proposed 

federal wells associated with state-approved PODs 

Discussions with industry indicate future development 

would occur close to existing PODs characterized by

high percentages of federal minerals (personal 

communication, Bruce Williams,, March 2006).

Currently 367 federal APDs are pending approval 

within the boundaries of PODs previously approved by 

the state. 

The preferred alternative would also consider wells per 

watershed instead of wells per county (Table 4-1), 

reflecting the phased development alternative; however 

the watershed screen would not be applied. The highrange, RFD-predicted total number of state, private and

federal wells (18,225) would apply to the preferred 

alternative. The constraints (multiple screens) imposed 

under the preferred alternative would limit the impacts to 

key resources and would provide a process to determine 

if development proposals would have to be modified to 

alter the pace or place of development. The assumed rate 

of development for the preferred alternative over the next 

21 years is identified in Table 4-5 and shown in Figure 4-

2. 

TABLE 4-5 

PREFERRED ALTERNATIVE H ASSUMED DEVELOPMENT RATE (APDS)

Year State/Private BLM Total Annual

1 488 119 607

2 586 324 910

3 500 575 1075

4 500 675 1,175

5 500 575 1,075

6 450 500 950

7 450 460 910

8 500 410 910

9 525 385 910

10 550 360 910

11 575 335 910

12 600 310 910

13 625 285 910

14 650 260 910

15 550 360 910

16 450 460 910

17 410 450 860

18 350 450 800

19 300 450 750

20 200 450 650

21 0 273 273

22 0 0 0 

23 0 0 0 

9,759 8,466 18,225
CHAPTER 4

Environmental Consequences 

4-9 

FIGURE 4-2 

PREFERRED ALTERNATIVE H ASSUMED DEVELOPMENT RATE 

0

200

400

600

800

1000

1200

1400

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Year

APDs

State BLM Total Wells

Estimates for the total number of compressors needed 

to export the gas are the same as predicted in the RFD.

The preferred alternative (Alternative H) differs from 

Alternative F as described below:

The preferred alternative would apply the condition on 

development in crucial sage-grouse habitat requiring

no displacement of sage-grouse within crucial habitat 

areas. Specifically, the preferred alternative calls for 

maintaining the connectivity of the habitats, managing 

habitat to maintain healthy sage-grouse populations to 

serve as source populations and within the crucial sage 

grouse areas, maintain sage-grouse habitat so that 

population trends follow the general magnitude of 

decline or increase on control leks. BLM would work 

with operators, the Montana Board of Oil and Gas

Conservation (MBOGC), the MFWP, the FWS and 

academia to identify best management

practices/conditions of approval (BMPs/COAs) 

universally applied to all CBNG development in 

crucial habitat areas. This approach would identify 

BMPs, apply BMPs and monitor the effectiveness of 

BMPs. Should BMPs prove unable to meet the 

objectives of maintaining habitat connectivity and 

source populations for sage-grouse, additional or more 

stringent existing BMPs would be identified and 

applied.

In Alternatives F & H, the condition for allowable 

development within sage-grouse habitat areas (i.e., 

development cannot contribute to displacement of 

sage-grouse from crucial habitat areas) would probably

lead to a lower number of wells drilled. The RFD 

predicted wells would be drilled on 80-acre spacing 

within the crucial sage-grouse habitat areas. Actual 

development in these areas might be significantly 

lower than predicted in the RFD. If operators chose to 

avoid all crucial habitat areas, approximately 

2,333 fewer wells would be drilled. If the private 

minerals were fully developed within the crucial sagegrouse habitat areas, 1,549 fewer wells would be 

drilled.

To quantify impacts under Alternative F, the original 

RFD development numbers were used to assess

impacts assuming operators could drill on current 

spacing and sage-grouse would not be displaced from 

habitat areas. Impacts were also quantified assuming 

no development would occur in these areas. This 

means 2,333 wells (with the associated roads, 

pipelines, compressors and produced water) would not 

be developed or installed. It also means gas would be 

left in place or drained from adjacent development. The 

most likely outcome would be somewhere between the 

full development and the no-development scenarios. 

Given the uncertainty associated with the effectiveness 

of alternative development scenarios regarding 

resource recovery, the low-end (no development) and 

high-end (full development) scenarios are used to 

bracket the impacts which would probably occur.
CHAPTER 4

Environmental Consequences

4-10

Alternative development scenarios could include a 

less-dense well pattern drilled within the habitat areas. 

Another potential scenario might be wells drilled on a 

denser spacing, but with fewer wells per year drilled 

within the habitat areas and no compressors installed 

on these sites. This does not suggest that these options 

would be viable, but rather points out that some level 

of development within the crucial sage-grouse habitat 

areas would probably occur. 

Assumptions Common to All 

Alternatives 

Assumptions common to all alternatives address issues 

such as level of disturbance associated with various 

development scenarios, implementation of best 

management practices (BMPs), general assumptions 

for percentages of alternative themes and numbers for 

various field equipment utilized, well spacing for 

production of CBNG and water discharge and 

drawdown rates for expanded development.

These assumptions are used to ground the analysis so 

that similar comparisons can be conducted across the 

various resource topics and throughout the alternatives.

Levels of Disturbance

In evaluating environmental impacts, criteria for 

determining quantitative impacts are required. Further, 

to facilitate some uniformity with respect to impact 

analyses, the following synopsis was prepared to give a 

general understanding of the resources necessary for 

the installation and production of a single CBNG well.

These values were determined from a variety of 

sources, including previous CBNG Environmental 

Assessments, discussions with BLM and state 

personnel, discussions with CBNG operators and

information derived from the review of numerous 

applicable documents. However, actual references are 

not provided as these numbers were ultimately derived 

through internal analysis based on understanding of 

current and proposed CBNG activities in Montana and 

other areas (including Wyoming, Colorado, New 

Mexico, Arkansas, Alabama and Oklahoma).

The values presented in Table 4-6 can be scaled to 

accommodate the various scenarios being proposed for 

exploration, construction and operation phases.

The following descriptions outline the assumptions 

used to develop Table 4-6. 

Well Sites

Construction = 0.25 acre based on a 105-foot by 

105-foot pad for exploration, construction and drilling 

operations 

Operations = 0.058 acre based on a 50-foot by 50-foot 

pad for operations, well pad size may increase if 

multiple wells are drilled on the same pad, but total 

acres of disturbance would be less than separate well 

pads for single wells.

Access Roads

Two-track = 0.30 acre based on 12-foot-wide roads by 

0.21 mile/well (this applies to both construction and 

operation)

Graveled Roads = 0.11 acre based on 12-foot-wide 

roads by 0.075 mile/well (this applies to both 

construction and operation)

Bladed Roads = 0.075 acre based on 12-foot-wide roads 

by 0.05 mile/well (this is for construction phase only)

Bladed Roads = 0.090 acre based on 12-foot-wide 

roads by 0.06 mile/well (this is for operation phase 

only) 

Bladed Roads = 0.75 acre based on 12-foot-wide roads 

by 0.5 mile/well (this is for exploration only)

Utility Lines

Water = 0.35 acre based on 15-foot by 0.20 mile/well 

(construction only)

Elec. Utility Overhead = 0.20 acre based on 10-foot by 

0.15 mile/well (construction and operation)

Elec. Utility Underground = 0.35 acre based on 15-foot 

by 0.20 mile/well (construction only)

Transportation Lines

Low Pressure Gas = 0.90 acre based on 15-foot by 

0.5 mile/well (construction only)

Intermediate Pressure Gas = 0.25 acre based on 25-foot 

by 0.08 mile/well (construction only)

Battery Site

Construction and Operation = 0.5 acre per battery site. 

Assume one battery site per field compressor. 

Disturbance per well = (0.5/24) = 0.020

Access Roads = 0.15 acre based on 25-foot by 0.050 mile 

per well during construction and operations

Field Compressors = 1 compressor per 24 producing 

wells
CHAPTER 4

Environmental Consequences

4-11

TABLE 4-6

LEVEL OF DISTURBANCE

Facilities

Exploratory Well 

Disturbance 

(acres/well)

Construction 

Disturbance (Shortterm < 5-yr.)

(acres/well)

Operation/Production 

Disturbance (Longterm >5-yr.)

(acres/well)

Well Sites 0.25 0.25 0.05

Access Roads/ Routes 

to Well Sites

Two-track N/A 0.30 0.30

Graveled N/A 0.10 0.10

Bladed 0.75 0.075 0.10

Utility Lines Water N/A 0.35 ----1

Overhead Elec. N/A 0.20 0.20

Underground Elec. N/A 0.35 ---- 

Transportation Lines Low Pres. Gas N/A 0.90 ---- 

Intermediate Pres. 

Gas

N/A 0.25 ---- 

Processing Area Battery Site N/A 0.020 0.020

Access Roads N/A 0.15 0.15

Field Compressor N/A ---- (0.5/24) = 0.02

1/24 producing wells

Sales Compressor N/A ---- (1.0/240) = 0.005

1/10 Field 

Compressors

Plastic Line2 N/A ---- 0.5

Gathering Line N/A ---- 0.25

Sales Line N/A ---- 0.075

Produced Water 

Management

Discharge Point N/A 0.01 0.002

Storage Impoundment N/A 0.3 0.25

Total Disturbance 1.0 3.25 2.0

Note: This table shows levels of disturbance associated with exploration and development of CBNG wells and field transfer equipment. All values 

represent acres per well unless otherwise noted.

1

All utilities are completed underground and the land above is reclaimed so the acres of disturbance are removed from the operation column. Note:

The intent of reclamation is to stabilize the area of disturbance and establish a vegetative cover similar to the native plant community that existed 

prior to disturbance. Reclamation success will vary as described in the Vegetation section.

2

Lines within processing area are assumed to disturb an average width of 25 feet.

Sales Compressors = 1 compressor per 240 producing 

wells or 10 field compressors

Plastic line = 0.5 mile per well pad. Assume 3 wells 

per pad, 25-foot width

Gathering line = 2.0 miles/field compressor at 25-

foot width or (5280*2*25/24/43,560) = 0.25 

acre/well

Sales line = 6.0 miles/sales compressor at 25-foot 

wide. (6*5280*25/240/43,560) = 0.075 acre/well

Produced Water Management

Assume 1 discharge point for every 20 wells

Discharge points construction = 0.01 acre/point based 

on 20-foot by 20-foot area during construction

Discharge points operations = 0.002 acre/point based 

on 10-foot by 10-foot area during operations

Storage impoundments = 6 acres/impoundment 

during construction per well pod of 20 wells, assume 
CHAPTER 4

Environmental Consequences

4-12

one acre reclaimed from construction so 5 

acres/impoundment during operation per POD of 20 

wells

The actual disturbance per well will be dependent on 

the actual site specific water management practices 

used.

Total Area of Disturbance

Exploration = 1.0 acres/well

Construction = 3.25 acres/well 

Operation = 2.0 acres/well 

Field Rules and Leasing Stipulations

The discussion of impacts assumes the leasing 

stipulations described for each resource would be 

successfully implemented by each of the permitting 

agencies in each of the alternatives. Use of existing 

Lease Stipulations and mitigation measures (see 

Minerals Appendix, Table MIN-5) is considered to 

be standard operating procedures by BLM.

The MBOGC issues field rules that address the 

spacing of wells based on such factors as geology, 

technology and economics. The MBOGC will 

provide guidance to private landowners if requested 

on how and what to include in their leases to protect 

resources, but it is up to the individual lessor as to 

what they request from the operator in terms of 

reclamation, mitigation and other measures. 

The Montana Trust Land Management Division 

(TLMD) of the Montana Department of Natural 

Resources and Conservation (DNRC) also has lease 

stipulations for their minerals as listed in the 

Minerals Appendix. The TLMD utilizes a set of 

standard stipulations on all oil and gas leases that is 

different from those used by BLM. Additional 

stipulations are placed on the leases on a case-bycase basis prior to their being leased. In addition, the 

TLMD undertakes a site-specific review process for 

exploration and operating plan proposals. This review 

process generates site-specific stipulations for issues 

such as steep topography, wildlife, streams, wooded 

areas and rivers and lakes. It was assumed that only 

requirements contained in existing federal and state 

law that apply to private land ownership will be 

enforced on private land.

Stipulations and field rules are intended to avoid 

potential effects on resource values and land uses 

from oil and gas activities and include actions such as 

site clearances and occupancy and timing restrictions. 

Lease stipulations would be implemented before 

conducting exploration, production and abandonment 

activities. The following discussion of project 

impacts assumes applicable stipulations and field 

rules would be fully implemented and followed. The 

success of these stipulations or field rules in avoiding 

covered impacts, in some instances, will require 

collection of site specific information regarding the 

resources to be protected relative to exploration, 

production and abandonment plans followed by strict 

adherence to the terms of the stipulations and field 

rules. Planned monitoring activities by the BLM for 

all resources have been outlined in a table attached in 

the Monitoring Appendix. Impacts described include 

those that would occur in spite of the successful 

implementation of stipulations or field rules, or 

where stipulations or field rules are not expected to 

avoid all impacts.

Proposed mitigation measures are intended to 

minimize the impacts that cannot be avoided. 

Mitigation measures also apply to all alternatives on 

BLM and state lands. Residual impacts are those 

expected to remain after the implementation of 

mitigation measures.

General Assumptions

Assumptions represent the best professional 

judgment of the specialist based on experience, 

similar occurrences and known circumstances and

studies. Assumptions that are common to all of the 

alternatives provide the foundation for the analysis of 

impacts. The following assumptions apply to each 

alternative:

• The spacing for CBNG wells would be similar to 

CBNG well spacing in Wyoming with one well 

per 80 acres per coal seam. Up to five coal seams 

have been identified for possible methane 

extraction in the Powder River Basin. However, 

for analysis purposes, it is assumed that an 

average of three wells would be drilled per 80-

acre spacing unit.

• The life of a typical CBNG production well is 

assumed to be 20 years, including construction 

and reclamation. 

• CBNG wells will come on line and go off line as 

described in the RFD.

• Water production for a single CBNG well can be 

estimated by the following equation:

Q = 14.661e-0.0242t

Where Q = discharge in gpm and t = time in 

months. The average production over 20 years 

using this equation is 2.5 gpm; however 
CHAPTER 4

Environmental Consequences 

4-13

discharge rates would begin at approximately 15 

gpm and decrease over time as the coal seam 

becomes depressurized. 

• The combination of the 2 preceding assumptions 

results in the maximum discharge for the total 

field occurring in year 6 of the development, for 

Alternatives B, C, D and E when 7,095 wells 

would be pumping at an average rate of 6.2 gpm 

to produce 43,989 gpm. This maximum 

produced water volume is used for the impact 

analysis. 

• Under phased development for Alternative F, the 

maximum amount of water produced in the field 

would occur in year 12 when 10,081 wells would 

probably pump at an average rate of 

3.5 gpm to produce 34,961 gpm. This maximum 

produced water volume is used for the impacts 

analysis for Alternative F.

• Under phased development for Alternative G, the 

maximum amount of water produced in the field 

would occur in year 12 when 3,577 wells would 

probably pump at an average rate of 

3.5 gpm to produce 12,390 gpm. This maximum 

produced water volume is used for the impacts 

analysis for Alternative G.

• Under Alternative H, the maximum amount of 

water produced in the field would occur in 

year 16 when 13,403 wells would probably

pump at an average rate of 2.9 gpm to produce 

39,400 gpm. This maximum produced water 

volume is used for the impacts analysis for 

Alternative H. 

• 20 percent of waters discharged will evaporate or 

infiltrate prior to reaching perennial waters.

• It is assumed that a single CBNG well will drain 

the methane from a single coal seam over an 80-

acre unit. Research by the BLM in the Wyoming 

portion of the Powder River Basin suggests 

drainage may be across a broader radius 

(Crockett and Meyer 2001). Drainage issues will 

need to be assessed on a case-by-case basis to 

determine the drainage radius, which will depend 

upon local reservoir parameters.

• The level of disturbance associated with a 

production well is the same regardless of the 

method of completion, whether a single well 

bore per coal seam or multiple seam completions 

in a well bore.

• Typical drilling operations for each CBNG well, 

regardless of whether it was a CBNG exploration 

or production well, would require 3 to 5 days 

with an additional 2 to 3 days for completion 

work. A maximum of 7 to 8 people would be 

present on a well at any one time during this 

construction phase.

• Approximately 26,000 gallons of water would be 

needed to drill each well. The water will 

typically be obtained from other producing 

CBNG wells in the area, or trucked into remote 

sites as needed.

• Equipment present at each well site during 

construction would consist of the following: one 

or two truck-mounted drill rig(s), with three men 

per rig; one backhoe; one blade; three crew pickup trucks; one well logging truck; one pipe truck; 

two to four water trucks; one cement truck; one 

electrical generator trailer; one frac tank for 

wastewater; and two large flat bed trailers. Not 

all vehicles would be at the well site at the same 

time or for the entire duration of drilling and 

completion operations.

• Portable toilets would be available at the drill 

sites. Garbage would be stored in closed 

containers. Sewage and solid waste would be 

hauled offsite to permitted disposal facilities.

• Each CBNG well would be equipped with a 

submersible pump ranging from 3 to 

20 horsepower, depending on well depth, 

required pumping rate and other site conditions.

• Exploration wells would be visited once a day 

during testing and pumping operations. Pump 

tests could last as long as 6 months depending on 

the time required for measuring cumulative 

methane production estimates. Methane would 

be flared (burned off) continuously during the 

testing phase.

• Fuel for generators during exploration testing 

would be either gas (propane) or diesel and 

require at least one trip to the well site weekly. 

Small generators used during testing would be 

mobile, enclosed and between 15 to 20 kilowatts 

(kW).

• A larger generator used during production would 

serve several wells (three to four) and be in the 

range of 75 to 125 kW.

• The selected alternative (Alternative 2A) for 

water and that portion of Alternative 1 regarding 

the use of natural gas fired compressors for the 

Wyoming Powder River Basin oil and gas 

projects will be implemented under all 
CHAPTER 4

Environmental Consequences

4-14

alternatives. This alternative assumes continued 

development of CBNG and conventional oil and 

gas resources would occur in the Wyoming 

Powder River Basin Planning Area. Up to 

39,367 additional CBNG wells and 3,200 

conventional oil and gas wells would be 

developed over the next 10 years. 

• Under Alternatives B through H, the number of 

exploration/dry holes would be approximately 

10 percent of the total estimated wells drilled.

• Under Alternatives B through E all 

exploration/dry holes would be drilled in the first 

5 years of development. Under Alternatives F, G 

and H, exploration/dry holes would comprise 

approximately 10 percent of the wells drilled 

annually. 

• Under Alternatives A and C, the number of wells 

connected to each compressor would be per 

operators plans; it is assumed that this is 

consistent with the RFD of 24 wells per 

compressor. This estimate is based on an average 

well production rate of 250,000 cubic feet per 

day methane being sent to a 6 million cubic feet 

per day, four-stage reciprocal compressor 

operating at 380 horsepower and using natural 

gas.

• Under Alternatives B, D, E, F, and G the number 

of wells connected to each compressor would be 

maximized; this is assumed to be approximately 

35 wells at average production going to a 

9 million cubic feet per day, four-stage 

reciprocal compressor. Under Alternative H, the 

number of wells connected to each field 

compressor reflects what is currently practiced 

by operators within the Montana portion of the 

PRB which is 40 wells per compressor. The 

maximization of well connections would reduce 

the number of field compressor sites and 

subsequently air emissions. 

• No hydraulic fracturing or cavitation would be 

required to stimulate wells; however, low-pressure, 

low-volume water enhancement may be used. 

This would involve flushing the well with a few 

hundred gallons of water to clean the face of coal 

surface in the exposed seam. This process does 

not fracture the coal; it simply cleans out the 

existing fractures.

• Under Alternatives B and D in the theme of 

CBNG, multiple completions in a single 

borehole would be required. It is assumed that a 

small reduction in surface disturbance would be 

experienced, but that the levels of disturbance 

previously described are acceptable for these 

alternatives without alteration.

• Under Lands and Realty, when no transportation 

corridors are required, it is assumed the utility 

lines (power, water and gas) would be placed 

along separate routes, or in existing disturbances 

to and from the well site locations or compressor 

batteries, whichever is more suitable to the 

operator. When transportation corridors are 

required, it is assumed they would be placed 

adjacent to access roads and along existing 

disturbances, resulting in a 35 percent reduction 

of disturbed surface areas.

• Concerning Socioeconomics it is assumed the 

state would not enforce buffer zones on their 

minerals or on private minerals since they do not 

have a trust responsibility.

• The potential development on the reservations 

would be considered under the cumulative 

effects analysis based on the development 

outline in the RFD for the reservations.

• Under the Hydrology theme for Alternative B, 

untreated CBNG water from exploration wells 

would be placed in tanks and disposed of at a 

permitted injection well. It is assumed the use of 

pits, impoundments and other holding facilities 

as permitted under Alternative A would be 

allowed. In addition, it is assumed produced 

water would be injected into a deeper aquifer of 

lesser quality with no communication to aquifers 

used as sources of drinking water or into coal 

seam aquifers.

• Under the Hydrology theme for Alternatives C 

and D, produced water would be available for 

beneficial use. It is assumed industries and 

landowners would use approximately 20 percent 

of the produced water. The estimate of 20 

percent is based on the observed beneficial uses 

at the CX Ranch and in Wyoming and on the 

perceived potential for similar uses throughout 

the Planning Area. 

Assumption Rationale

CBNG Well Production Life

The rationale for using a 20-year lifespan for a 

typical CBNG well in Montana is based on several 

technical considerations as well as the best 

professional judgment of several specialists. The well 

life is based on the economic limit selected for the 
CHAPTER 4

Environmental Consequences 

4-15

well, the wide variety of geologic basins in Montana, 

the data limitations, the variations in the rank of coals 

that may be encountered in Montana and a review of 

the well life of CBNG wells in other producing 

basins, including Wyoming and the San Juan Basin. 

These rationales are generally summarized below:

Montana Planning Area: The Planning Area for the 

FSEIS for BLM is the Billings and Powder River

RMPs. Although an emphasis was placed on the 

Powder River Basin, assumptions used were derived 

for the entire Planning Area based on existing 

available information. CBNG production in Montana 

and Wyoming is relatively new as compared to 

conventional oil and gas production in either of these 

states. In Montana, approximately 550 producing 

CBNG wells exist in the CX Ranch Field near 

Decker, Montana. Throughout Montana, very little 

information is available relative to CBNG production 

or testing outside of the current producing area at CX 

Ranch. Further, there are a variety of underground 

coal seams that must be considered, including areas 

in the Powder River Basin, Bull Mountain Basin and

areas elsewhere in the state (including the entirety of 

the two BLM RMPs).

1. Economic Production Limits on CBNG Wells: 

The BLM in Wyoming selected an average 

production life for CBNG wells in the Planning 

Area based on production decline analysis from 

existing production on federal leases. These 

analyses assume an economic limit of 

approximately 1,000 thousand cubic feet (MCF) 

per month (personal communication, Bob Chase, 

BLM). CBNG producers currently operating in 

the Wyoming Powder River Basin suggested the 

economic limit of 1,000 MCF per month to the 

BLM. Based on Wyoming’s limited planning 

area and the extent of existing data available that 

is directly within the Planning Area, this 

approach appears justified. To date, no wells 

have been confirmed as reaching their economic 

limit in the Powder River Basin in either 

Wyoming or Montana. Several wells have 

reached monthly production of less than 1,000 

MCF per month and several other wells have 

been shut-in. However, based on existing 

knowledge of CBNG operations, it is not clear 

whether shut-in wells will remain shut-in without 

further production.

The economic limits used by the Wyoming BLM 

of 1,000 MCF per month appear reasonable for 

planning in the Wyoming portion of the basin. 

However, there are many examples of wells 

producing at rates of less than 1,000 MCF per 

month for considerable periods. The Wyoming 

portion of the Powder River Basin has 

production rates less than 1,000 MCF while 

continuing to produce. However, it is currently 

unknown whether CBNG wells in the Montana 

Powder River Basin will be shut-in and plugged 

once a production rate of 1,000 MCF per month 

is achieved.

Of further consideration is the rationale that the 

proposed economic production limit used in the 

Wyoming EIS is based on certain economics 

provided by operators currently producing in 

Wyoming. Many of these producers are 

relatively large businesses. In the case of 

conventional oil and gas production, it is 

common for larger producers to sell production 

to smaller companies that may be capable of 

operating projects at a lesser cost—especially 

later in the life of the project when production 

rates are substantially reduced. This progression 

of producing properties transitioning from large 

companies to smaller companies supports the

argument that the viable economic production 

life of a CBNG well could be less than 1,000 

MCF per month. This is especially significant 

considering the socioeconomic situation in 

Montana and especially relative to the Northern 

Cheyenne and Crow reservations. 

2. Geologic Differences: Because the Montana 

Planning Area includes the entire state, there are 

significant differences in geology when 

comparing assumptions used for impact analyses 

between the two plans.

3. Data Limitations: CBNG production in 

Montana and Wyoming is relatively new as 

compared to conventional oil and gas production 

in either of these states. In Montana, 

approximately 550 producing CBNG wells exist 

in an area near Decker, Montana. Throughout 

Montana, little information is available relative 

to CBNG production or testing outside of one 

current producing area at CX Ranch. Further, 

there are a variety of underground coal seams 

that must be considered, including areas in the 

Powder River Basin, Bull Mountain Basin and

areas elsewhere in the state (including the 

entirety of the two BLM RMP areas). Figure 4-3 

presents production data for the CX Ranch field 

near Decker, Montana (MBOGC 2005). This 

figure shows that actual production of CBNG in 

Montana started in April 1999.
CHAPTER 4

Environmental Consequences 

4-16

FIGURE 4-3 

CBNG PRODUCTION CX RANCH FIELD 

0

200000

400000

600000

800000

1000000

1200000

1400000

Jun-98

Dec-98

Jun-99

Dec-99

Jun-00

Dec-00

Jun-01

Dec-01

Jun-02

Dec-02

Jun-03

Dec-03

Jun-04

Dec-04

Jun-05

Dec-05

Month/Year

CBNG Production (Mcf)

CBNG Production

(Mcf)

4. Variations in Rank of Coal: Coals in the 

Powder River Basin are all of Tertiary age 

throughout both Montana and Wyoming. 

However, the Montana Planning Area includes 

coals that are much older and of higher rank. For 

instance, the coal seams near Bozeman Pass and 

Great Falls are of Cretaceous age and have an 

overall higher rank than Powder River Basin 

coals. This suggests that these coals may contain 

methane that is more thermogenic in nature than 

biogenic. Although there is not any existing 

production data for areas other than the CX 

Ranch in Montana, it is reasonable to assume 

that CBNG wells in these areas may produce 

economic quantities of methane for longer 

durations than in the Powder River Basin 

without the benefit of historical production data. 

In certain situations, where multiple coal beds 

are present, a well’s productive life can be 

extended by reworking the well to produce gas 

from deeper coal beds. For example, well 

completions in multiple coal beds could extend 

the life of a well site by 10 to 30 years. 

Studies of CBNG wells in the San Juan Basin, which 

produce from greater depths than CBNG wells in the 

PRB, have projected CBNG gas production for 20 

years. The deeper coal in other basins of Montana 

may produce in a similar fashion and have a well life 

of 20 years.

Differences in Produced Water Sodium 

Absorption Rate (SAR) and Electrical 

Conductivity (EC) Values

These differences are based on differences that exist 

across the basin. These differences are based on 

geologic and the available produced water data for 

each state. The geologic differences relate to how the 

coal seams change northward across the basin. In 

Wyoming, the coals seams are thicker (averaging up 

to 250 feet or more in aggregate thickness in many 

areas) and more continuous, northward in the basin 

into Montana, the coal seams thin (generally less than 

100 aggregate feet) and become locally 

discontinuous.

In Montana there is a limited data set with little data 

outside the CX Ranch, which was used as the basis 

for the SAR and EC values in the DEIS. The 

produced water data available for the Montana 

Powder River Basin indicates there are significant 

differences in water quality in the northern part of the 

basin in comparison to the Wyoming portion of the 

Powder River Basin. The water quality data available 

for Montana varies enough from Wyoming that using 

the Wyoming data for impact analysis in Montana 

would underestimate the potential impacts in 

Montana.
CHAPTER 4

Environmental Consequences 

4-17

Maximum Drawdown in Coal-Seam 

Aquifers

The Montana Bureau of Mines and Geology 

(Wheaton and Metesh 2002) released a report on the 

potential groundwater drawdown and recovery in the 

Montana portion of the Powder River Basin. The 

results of this report indicate that drawdown within 

the coal seams could be as high as 240 to 600 feet 

within the well field. The report also indicated 

drawdown as high as 300 feet in the interburden units

and 6 feet in the overburden units. The results of the 

model showed drawdown up to 30 feet at a distance 

of approximately two miles from the well field and 

drawdown of five feet at a distance of approximately 

seven miles. The results of this model have been used 

for the impact analysis in this document. 

Decrease Flow in Surface Water

In the Montana portion of the Powder River Basin, 

the bulk of the coals of the Fort Union Formation are 

confined to the Tongue River Member, while the 

Lebo and Tullock Members are predominantly shale 

and shaley sand (McLellan et al. 1990). Because of 

the confined nature of the coals and lack of the 

Wasatch Formation in Montana, the production of 

CBNG water is not expected to result in decreases to 

surface water base flows. There are also several 

potential increases to flow that may mask any 

potential decreases in surface water flow. The 

discharge of CBNG-produced water to the ground 

surface and surface waters would mask any reduction 

in flow in the surface waters. 

Beneficial Use of CBNG Production Water 

The Montana EIS preparation team assumes 

20 percent of the produced water will be available for 

beneficial purposes in Alternatives C and D. Under 

Alternatives E, F, G and H it is assumed that 

emphasizing beneficial uses combined with increased 

flexibility for water management practices should 

result in an increase in beneficial water usage. The 

beneficial uses envisioned are based on current 

practices, such as livestock watering, creation of 

wildlife watering areas (Environmental News 

Network 2001), coal mine dust suppression (Fidelity 

2001), irrigation, constructed wetlands (Davis 1995), 

domestic water supply, produced water as drilling 

fluid (Clark and Hemler 1992), de-icing of road 

aggregate storage piles (DeWalle and Geleone 1990)

and enhancement of fisheries and riparian zones 

(Wyoming Game and Fish Department, n.d.).

Wyoming RFD Impacts 

The Montana EIS accounts for the full scale of 

development proposed by the current Wyoming RFD

(which has since been adopted). In the Minerals 

Appendix an expanded discussion regarding both the 

Wyodak RFD of 6,000 wells and the current 

Wyoming RFD with a proposed new 39,400 wells is 

addressed. Furthermore, within the Hydrology and 

Air sections of Chapter 4 under the Conclusions for 

Alternative A the effects of the expanded Wyoming 

RFD is acknowledged and accounted for in the 

impact analysis. These conclusions are also 

referenced under the other alternatives conclusion 

sections for cumulative impacts because they address 

the full range of possible impacts from Wyoming 

CBNG development.
CHAPTER 4

Air Quality and Climate

4-18

Resource Topics

Air Quality and Climate

Air Quality

Existing air quality throughout most of the analysis area is in 

attainment with all ambient air quality standards. However, three 

areas have been designated as federal nonattainment areas where 

the applicable standards have been exceeded in the past: Lame 

Deer (PM10—moderate) and Laurel (SO2—primary), Montana; 

and Sheridan, Wyoming (PM10—moderate).

Air emission impacts based on modeling show potential impacts 

only. Potential impacts would be mitigated through project 

level permitting by federal, state, or tribal regulatory agencies.

Alternatives A, B and D were modeled in the 2003 Final

Statewide EIS based upon the modeling domain and receptor 

grids used in the Technical Support Document (Argonne 2002).

Alternatives C and E were not modeled, as their emission 

sources were essentially the same as for Alternative B.

Alternatives E, F and H were subsequently modeled for this 

FSEIS by using an updated grid system, which expanded the 

near-field receptor grid; an updated meteorological base year 

(2002); updated emission sources to the most currently 

available data (2004); and updating RFFAs to include the TRR. 

Alternative G was not modeled, but would represent emission 

levels of approximately 65 percent of Alternative F due to only 

65 percent of CBNG wells being completed in this scenario. 

Additionally, CO was not modeled for Alternatives E, F and H 

in the FSEIS, as initial modeling conducted in the 

2003 Oil and Gas EIS showed impacts were quite small in 

relation to existing applicable air quality standards.

In 2007, BLM prepared a Supplemental Air Quality Analysis to 

assess the level of CBNG development that would require 

mitigation to reduce the potential for impacts to air quality. The 

Supplemental Air Quality Analysis provides additional 

information and analyses regarding the level of CBNG 

development that would have the potential to impact air quality 

within the Powder River and Billings RMP areas. It includes an 

analysis and comparison of the potential for CBNG 

development to impact air quality under different air quality 

emission rates under the preferred alternative (Alternative H). 

The information contained within the Supplemental Air Quality 

Analysis is intended to expand on the air quality information 

presented in the DSEIS and the Air Quality Technical Support 

Document (revised October 2007).

Alternative A

No Action (Existing CBNG Management)

• Localized short-term increases in CO, NOx, SO2, PM2.5

and PM10 concentrations.

• Maximum concentrations would be below applicable 

state and National Ambient Air Quality Standards and 

PSD increments for near-field and far-field modeling.

• Potential direct impact on visibility within one 

mandatory federal PSD Class I, one Class II Area and 

the Class II Crow Reservation. 

• Cumulative Impacts:

− Potentially exceed the 24-hour PM10 NAAQS and 

PSD Class II increments south of Spring Creek 

Mine.

− Potentially exceed PSD Class I increments for 24-

hour PM10 on the Northern Cheyenne Reservation.

− Potentially exceed atmospheric deposition 

thresholds in the very sensitive Upper Frozen Lake 

in the PSD Class I Bridger Wilderness Area. 

− Potential visibility impacts in 10 of 17 federal PSD 

Class I including the Crow and Fort Peck 

reservations. Additional visibility impacts to 7 of 

13 PSD Class II sensitive areas including the Crow 

and Fort Belknap reservations. 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Localized short-term increases in CO, NOx, SO2, PM2.5

and PM10 concentrations. 

• Maximum concentrations are expected to be below 

applicable state and NAAQS and PSD increments for 

near-field and far-field modeling.

• Potential direct visibility impacts within seven mandatory 

federal PSD Class I Areas and the Northern Cheyenne 

Reservation. Additional visibility impacts to seven federal 

PSD Class II areas including the Crow and Fort Belknap

Reservations and three Wilderness Areas and one 

National Recreation Area and one National Monument. 

• Cumulative Impacts:

− Potentially exceed the 24-hour PM10 and PM2.5

NAAQS south of Spring Creek Mine.

− Potentially exceed the PSD Class II increments for 

24-hour PM10 south of Spring Creek Mine.

− Potentially exceed PSD Class I increments for 24-

hour PM10 on the Northern Cheyenne Reservation

and Washakie WSA.

− Potentially exceed PSD Class I increments for 

annual NO2 on the Northern Cheyenne Reservation. 

− Potentially exceed atmospheric deposition 

thresholds in the very sensitive Upper Frozen Lake 

in the PSD Class I Bridger Wilderness Area and 

Florence Lake in the Class II Cloud Peak Wilderness 

Area.

− Potential visibility impacts in all federal PSD Class I 

and II sensitive areas including the Northern

Cheyenne, Fort Peck, Fort Belknap and Crow 

reservations.

Alternative C

Emphasize CBNG Development

• Impacts under Alternative C are expected to be 

comparable to those describe for Alternative B but 

somewhat increased in severity due to the lack of control 

over operators choice of compressor fuel, reduced limits 

on compressor hook ups and the lack of enforceable 

control measures.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Localized short-term increases in CO, NOx, SO2, PM2.5

and PM10 concentrations. 

• Maximum concentrations are expected to be below 

applicable state and NAAQS and PSD increments for 

near-field and far-field modeling.

• Potential direct visibility impacts within one mandatory 

federal PSD Class I Areas. Additional visibility impacts to 

three PSD Class II areas including the Crow Reservation, 

one Wilderness Area and one National Recreation Area. 

• Cumulative Impacts:

− Potentially exceed the 24-hour PM10 and PM2.5
CHAPTER 4

Air Quality and Climate

4-19

NAAQS south of Spring Creek Mine.

− Potentially exceed the PSD Class II increments for 

24-hour PM10 south of Spring Creek Mine.

− Potentially exceed PSD Class I increments for 24-

hour PM10 on the Northern Cheyenne Reservation

and Washakie WSA.

− Potentially exceed atmospheric deposition 

thresholds in the very sensitive Upper Frozen Lake 

in the PSD Class I Bridger Wilderness Area.

− Potential visibility impacts in 14 of 17 federal PSD 

Class I and all Class II sensitive areas including the 

Northern Cheyenne, Fort Peck, Fort Belknap and 

Crow reservations.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts while 

Maintaining Existing Land Uses

• Impacts modeled for Alternative E would consist of the 

potential for localized short-term increases in NOx, SO2, 

PM10 and PM2.5 concentrations. 

• Maximum concentrations resulting from project-related 

activities are expected to be below applicable state and 

NAAQS and PSD increments.

• Alternative E would not result in a change in acid 

neutralizing capacity above significance thresholds for any

Class I areas in the modeling domain.

• Visibility impacts above 1.0 dv would occur in 7 to 10 PSD 

Class I areas and 6 to 12 PSD Class II Areas. 

• Given the non-project emission sources located throughout the 

analysis region, there would be a potential for cumulative air 

quality impacts to exceed applicable thresholds under 

Alternative E. However, none of the predicted impacts 

exceeds state or NAAQS.

• The air-quality permitting process would be used to analyze 

emission sources at the project level. Emission sources that 

would violate standards would not be permitted by the 

agencies; therefore, residual impacts would remain within 

standards.

Alternative F

Phased Development Multiple Screens (High Range)

• Impacts under Alternative F would be comparable to those 

described for Alternative E, but would be fewer and would 

level off over time due to the 5 percent annual limit for

applications for permit to drill (APDs) approved on BLMadministered surface. 

• Cumulative impacts under Alternative F would be the same 

as for Alternative E.

• The air quality permitting process would be used to analyze 

emission sources at the project level. Emission sources that 

would violate standards would not be permitted by the 

agencies; therefore, residual impacts would remain within 

standards.

Alternative G

Low-range, Phased CBNG Development

• Impacts under Alternative G would be fewer than for 

Alternatives E or F due to a lower number of wells predicted 

to be drilled. This would result in a reduction of 

approximately 65 percent in the number of compressors that 

would be required. Fewer well pads and roads would also 

have to be constructed. 

• Cumulative impacts under Alternative G would be fewer 

than for Alternatives E or F due to 65 percent less wells 

predicted to be drilled. This would result in construction of 

approximately 65 percent fewer compressors, well pads and

roads.

• The air quality permitting process would be used to analyze 

emission sources at the project level. Emission sources that 

would violate standards would not be permitted by the 

agencies; therefore, residual impacts would remain within 

standards.

Alternative H

Preferred Alternative - Multiple Screens

• Impacts under Alternatives H would be less than those 

described for Alternative E due to the implementation of the 

air quality screen for CBNG development. 

• Cumulative impacts under Alternatives H would be less than

those described for Alternative E due to the implementation 

of the air quality screen for CBNG development. 

• The air quality permitting process would be used to analyze 

emission sources at the project level. Emission sources that 

would violate standards would not be permitted by the 

agencies; therefore, residual impacts would remain within 

standards.

ASSUMPTIONS

Potential air quality impacts for Alternatives A, B

and D were evaluated using the air quality model 

conducted for the 2003 Montana Statewide Final Oil 

and Gas Environmental Impact Statement and 

Proposed Amendment of the Powder River and 

Billings Resource Management Plans (Statewide 

Document) (Argonne 2002). Alternatives C and E

were not modeled for the Statewide Document, as 

their emission sources were essentially the same as 

for Alternative B. Those data and the impact analysis 

based on that modeling effort are retained in this

FSEIS. Alternatives E, F and H were subsequently 

modeled for this FSEIS using an updated receptor 

grid system (which expanded the near-field receptor 

grid), an updated meteorological base year (2002), 

updated emission sources to the most currently 

available data (2004) and updating the reasonably 

foreseeable future actions (RFFAs) to include the 

TRR. Alternative G was not modeled, but would 

represent potential emission impacts at approximately

65 percent of Alternative F due to that percent fewer 

CBNG wells being completed under Alternative G 

compared to Alternative F. 

Three groups of emission sources contribute to the 

modeled emission results. They are existing 

emissions, CBNG project-related emissions and 

RFFA emissions. Existing emissions consist of 

emissions from those sources that currently exist for 

the baseline year of 2004. Existing emission data 

were obtained from the appropriate state regulatory 

agencies as well as the Western Regional Air Project 

(WRAP) database. CBNG project-related emissions 

were developed on the basis of the RFD scenario 

outlined in the Minerals Appendix and modified for 
CHAPTER 4

Air Quality and Climate

4-20

elements specific to each alternative. CBNG projectrelated emissions were further broken down into 

emissions that result from construction activities and 

emissions that result from operations and 

maintenance activities. RFFA emissions consist of 

those that would result from projects or facilities not 

currently operating, but reasonably expected to 

operate sometime during CBNG development. 

Examples of RFFA emission sources would be the 

TRR or the Roundup Power Plant.

The modeling methodology and detailed results for 

the model conducted for this FSEIS are contained 

within the Air Quality Appendix. A summary of the 

results is found in the impact analyses for 

Alternatives E, F and H, as well as a discussion of

potential impacts for Alternative G.

Although the CBNG development (project sources) 

and non-project sources emit carbon dioxide and 

methane, climate impacts are anticipated to be small 

from implementation of any of the alternatives. 

Climate impacts may even be beneficial to the extent 

that:

• Development of the CBNG resource reduces the 

natural emissions of methane from coal mines

• Use of CBNG displaces combustion of coal or 

oil, both of which emit more carbon dioxide than 

methane per unit energy produced.

Carbon monoxide (CO) was not modeled for 

Alternatives E, F and H in the FSEIS, as initial 

modeling conducted in the Statewide Document 

(Argonne 2002) showed impacts were quite limited 

relative to existing applicable air quality standards.

The potential for ozone formation due to projectrelated sources was not included as part of the FSEIS

modeling effort. The decision to not include ozone 

within the modeled constituents was based on results 

predicted in previous modeling efforts conducted for 

the Coal Study (ENSR 2005a, 2005b) and the 2003 

Oil and Gas EIS (Argonne 2002). These modeling 

efforts indicated that primary pollutants (oxides of 

nitrogen [NOx]), CO and non-methane volatile

organic compounds (VOCs), which are known to be 

precursors required for the formation of ozone, would 

not be produced from project-related sources at levels 

that would contribute to ambient ground level ozone 

concentrations to any measurable extent.

With respect to analysis of prevention of significant 

deterioration (PSD) increments, a regulatory PSD 

increment analysis has to include all historic emission 

changes since the PSD trigger date, which extends 

back to 1978 for the area around Colstrip. Both 

increment expansion and consumption have taken 

place since that date. An analysis of this sort is 

beyond the scope of this project. The Montana 

Department of Environmental Quality (MDEQ), in 

cooperation with the Northern Cheyenne Tribe and 

the Environmental Protection Agency (EPA), is 

conducting this type of analysis. The results will be 

factored into the new source review process in 

permitting additional CBNG sources in the study 

area.

Potential impacts to air quality are summarized in 

this section. A more complete summary of the 

modeled potential air quality impacts for Alternatives 

A thru D are given in the Air Quality Appendix - Part 

1 with a highly detailed description of the air quality 

modeling given in Argonne 2002. The Air Quality 

Appendix—Part 2 for this FSEIS—includes a 

detailed description of the methodology and results of 

the air quality modeling conducted for this FSEIS for 

Alternatives E, F and H.

Issues, Impact Types and Criteria

Fugitive dust and exhaust from construction 

activities, along with air pollutants emitted during 

operation (e.g. well operations, field and sales 

compressor engines), are potential causes of air 

quality impacts. These issues are more likely to 

generate public concern where natural gas 

development activities occur near residential areas. 

The Federal Land Managers (FLM), including the 

U.S. Department of Agriculture (USDA), USFS; the 

U.S. Department of Interior (USDI), National Park 

Service (NPS); and the USDI, U.S. Fish & Wildlife 

Service (FWS), have also expressed concerns 

regarding potential atmospheric deposition and 

visibility impacts within PSD Class I and PSD Class 

II areas under their administration, located 

throughout Montana, Wyoming, southwestern North 

Dakota, western South Dakota, northwestern 

Nebraska and southeastern Idaho.

Air pollution impacts are limited by local, state, tribal 

and federal air quality regulations, standards and

implementation plans established under the Clean Air 

Act (CAA) and administered by the MDEQ—Air 

Resources Management Bureau and the EPA. 

Although not applicable to the proposed Alternatives, 

the Wyoming Department of Environmental 

Quality—Air Quality Division (WYDEQ) has similar 

jurisdiction over potential air pollutant emission 

sources in Wyoming, which can have a cumulative 

impact with MDEQ approved sources. Air quality 

regulations require certain proposed new, or modified 

existing, air pollutant emission sources (including 

CBNG compression facilities) to undergo a 

permitting review before their construction can begin. 
CHAPTER 4

Air Quality and Climate

4-21

Therefore, the applicable air quality regulatory 

agencies have the primary authority and 

responsibility to review permit applications and to 

require emission permits, fees and control devices, 

prior to construction and/or operation.

In addition, the U.S. Congress (through the CAA 

Section 116) authorized local, state and tribal air 

quality regulatory agencies to establish air pollution 

control requirements more (but not less) stringent 

than federal requirements. Site-specific air quality 

analysis would be performed and additional emission 

control measures, including a best available control 

technology (BACT) analysis and determination, may 

be required by the applicable air quality regulatory 

agencies to ensure protection of air quality resources. 

Also, for resources discussed in this SEIS, the BLM 

will not authorize any activity that does not conform 

to all applicable local, state, tribal and federal air 

quality laws, regulations, standards and

implementation plans.

The significance criteria for potential air quality 

impacts include local, state, tribal and federally 

enforced legal requirements to ensure air pollutant 

concentrations would remain within specific allowable 

levels. These requirements include the National and 

Montana Ambient Air Quality Standards, which set 

maximum limits for several air pollutants and PSD 

increments, which limit the incremental increase of 

NO2, sulfur dioxide (SO2) and particulate matter less 

than 10 microns in diameter (PM10) concentrations 

above legally defined baseline levels. These legal 

limits were presented in Chapter 3. Where legal limits 

have not been established, the BLM uses the best 

available scientific information to identify thresholds 

of significant adverse impacts. Thresholds have been 

identified for hazardous air pollutant (HAP) exposure, 

potential atmospheric deposition impacts to sensitive 

lake water chemistry and a “just noticeable change” in 

potential visibility impacts.

An extensive air quality modeling technical support 

document was prepared by Argonne National 

Laboratory (Argonne 2002) and is summarized in the 

Air Quality Modeling Appendix of the Statewide 

Document (BLM 2003). This technical report is 

available for review (contact information is given in 

the Air Quality Appendix – Part 1). Argonne 

modeled potential changes in air quality from 

individual Alternatives A, B, C, D and E, non-project 

emission sources and all sources cumulatively by 

alternative. Since Alternatives B, C and E have 

similar emission inventories, a single air quality

analysis represents all three alternatives.

An Air Quality Model Technical Support Document

(AQTSD, revised October 2007) and a Supplemental 

Air Quality Analysis (SAQA) report were also 

prepared for the modeling effort conducted for this 

FSEIS. These documents are available for review on 

the FSEIS project website at

http://www.blm.gov/eis/mt/milescity_seis/. 

The air quality modeling was based on the best 

available engineering data and assumptions, 

meteorology data and dispersion modeling procedures, 

as well as professional and scientific judgment. 

Due to the regional nature of this analysis, it should be 

considered a reasonable estimate of predicted impacts. 

Actual impacts at the time of project level 

development (subject to air pollutant emission source 

permitting) are likely to be less.

The EPA CALPUFF dispersion model was used with 

meteorological data generated by the MM5 (mesoscale 

model) and CALMET models. Meteorological 

information was assembled to characterize 

atmospheric transport and dispersion from several 

1996 data sources, including the following: 

1) 36 km gridded MM5 (mesoscale model) values 

with continuous four-dimensional data 

assimilation

2) Hourly surface observations (wind speed, wind 

direction, temperature, cloud cover, ceiling 

height, surface pressure, relative humidity and

precipitation)

3) Twice-daily upper air vertical profiles (wind 

speed, wind direction, temperature and pressure)

4) PRISM-adjusted hourly precipitation 

measurements

Potential air pollutant emissions from the 

alternatives’ emission sources (denoted as project 

sources) were calculated separately to determine 

potential impacts. These emissions were then 

combined with existing sources, proposed nonPowder River Basin oil and gas developments, RFFA 

emissions (denoted as non-project sources) and

RFFA emissions from potential CBNG development 

on the Northern Cheyenne and Crow reservations and 

the Ashland District of the Custer National Forest to 

determine the total potential cumulative air quality 

impacts. All of the tables in this analysis and the Air 

Quality Appendix display modeled emissions from 

the following: 

1) The project sources only

2) The project sources combined with emissions 

from potential CBNG development on the 

Northern Cheyenne and Crow reservations and 

the Ashland District of the Custer National 

Forest (denoted as “Project + RFFA Sources)
CHAPTER 4

Air Quality and Climate

4-22

3) The non-project sources

4) Cumulative totals

The non-project sources include development 

permitted by the following agencies and states: 1) 

MDEQ; 2) WYDEQ; and 3) within the states of 

North Dakota, South Dakota and Nebraska; and 

projections for the Wyoming Powder River Basin Oil 

and Gas Project DEIS Alternative sources (BLM 

2002a); and other RFFA sources from states within 

the geographic area covered by the model. Table 4-7 

shows total emissions from the non-project permitted

and other RFFA sources, Wyoming Powder River

Basin oil and gas project sources and Montana 

Powder River Basin oil and gas project sources, 

combined with RFFA sources. These emissions are 

for Alternatives B, C and E; Alternative A and D 

emissions would be lower and potential CBNG wells 

on the Northern Cheyenne and Crow reservations and 

the Ashland District of the Custer National Forest 

have been included with emissions for Alternatives 

B, C and E.

The meteorology data and air pollutant emission 

values were combined to predict maximum potential 

direct, indirect and cumulative near-field air quality 

impacts in the vicinity of assumed well and 

compressor engine emission sources for comparison 

with applicable air quality standards and PSD Class 

II increments. Maximum potential near-field 

particulate matter emissions from traffic on unpaved 

roads and during well pad and compressor station 

construction were used to predict the maximum 

annual and 24-hour average SO2, particulate matter 

less than 2.5 microns in diameter (PM2.5) and PM10

impacts. Maximum air pollutant emissions from each 

CBNG well would be temporary (i.e., occurring 

during a 12-day construction period) and would occur 

in isolation, without significantly interacting with 

adjacent well locations. Particulate matter emissions 

from well pad, compressor station and resource road 

construction would be minimized by application of 

water and/or chemical dust suppressants. The control 

efficiency of these dust suppressants was estimated at 

50 percent during construction. During well 

completion testing, natural gas could be burned 

(flared) on a single day.

Air pollutant dispersion modeling was also 

performed to quantify potential particulate matter, 

CO, NO2 and HAP impacts during operation. 

Operation emissions would primarily occur due to 

TABLE 4-7 

NON-PROJECT AND PROJECT TOTAL EMISSIONS SUMMARY

Source Category

Annual Emissions (tons/year)

NOx SO2 PM10 PM2.5 CO VOCs

Non-Project Sources (2006)

DM&E Sources 14,391 3,655 722 263 799 294

CDWII Sources 1,269 563 257 --- --- --- 

Wyoming Sources 7,250 1,773 2,691 1,028 13,505 2,795

Montana Sources 3,169 950 2,279 1,003 2,576 880

Nebraska & North Dakota Sources 1,114 26 102 48 449 132

New Sources Subtotal 27,192 6,966 6,051 2,343 17,329 4,101

Montana RFFA Sources 2,844 4,796 127 71 6,171 20

Wyoming RFFA Sources 1,578 3,381 298 155 3,381 -- 

South Dakota RFFA Sources 289 35 53 53 175 71

Other RFFA Sources Subtotal 4,710 8,212 478 279 9,277 91

Wyoming Alternative 1 Project Sources

(w/Project Year noted)

17,834

(Yr 5)

829

(Yr 3)

2,918

(Yr 6)

1,280

(Yr 5)

14,799

(Yr 5)

8,268

(Yr 5)

Total Non-Project Sources 49,737 16,007 9,447 3,902 41,855 12.460

Montana Alt. B, C and E Project + RFFA 

Sources (w/Project Year noted)

9,959

(Yr 18)

339

(Yr 5)

1,230

(Yr 5)

514

(Yr 15)

9,378

(Yr 20)

4,841

(Yr 20)

DM&E – Dakota, Minnesota and Eastern Railway Corporation

CDWII – Continental Divide/Wamsutter II and South Baggs Natural Gas Development Projects
CHAPTER 4

Air Quality and Climate

4-23

increased compression requirements, including field 

and sales compressor stations. Since produced natural 

gas is nearly pure methane and ethane, with little or 

no liquid hydrocarbons, direct VOC emissions are 

not likely. HAP impacts were predicted based on an 

assumed, six-unit, 1,650-horsepower each, 

reciprocating compressor engine station operating at 

full load with emissions generated by a single stack.

The EPA CALPUFF dispersion model was also used 

to determine maximum far-field ambient air quality 

impacts at downwind mandatory federal PSD Class I 

areas and other sensitive receptors, to accomplish the 

following: 

1) Determine if the PSD Class I increments might 

be exceeded

2) Calculate potential total sulfur and nitrogen 

deposition and their related potential impacts to 

sensitive lakes

3) Predict potential visibility impacts (regional 

haze) within distant sensitive receptors

The National Environmental Policy Act (NEPA) 

analysis compares potential air quality impacts from 

the proposed alternatives to applicable ambient air 

quality standards and PSD increments, but 

comparisons to the PSD Class I and II increments are 

intended to evaluate a threshold of concern for 

potential impacts and do not represent a regulatory 

PSD Increment Consumption Analysis. Even though 

most of the development activities would occur 

within areas designated PSD Class II, the potential 

impacts on regional Class I areas are to be evaluated. 

The MDEQ will perform the required regulatory PSD 

increment analysis during the new sources review 

process. This formal regulatory process will include 

analysis of impacts on Class I and II air quality areas 

by existing and proposed emission sources. The 

activities are not allowed to cause incremental effects 

greater than the stringent Class I thresholds to occur 

inside any PSD Class I Area. Stringent emission 

controls (BACT – Best Available Control 

Technology) and emission limits may be stipulated in 

air quality permits as a result of this review, or a 

permit could be denied.

Several lakes within five USFS-designated wilderness 

areas were identified as being sensitive to atmospheric 

deposition and for which the most recent and complete 

data have been collected. The USFS (Fox et al, 1989) 

has identified the following total deposition (wet plus 

dry) thresholds below which no adverse impacts to airquality related values (AQRVs) are likely: 5 kilograms 

per hectare per year (kg/ha-yr) for sulfur and 3 kg/ha-yr 

for nitrogen. The USFS Rocky Mountain Region has 

also developed a screening method (U.S. Department of 

Agriculture Forest Service - USFS 2000) which 

identifies the following Limit of Acceptable Change 

regarding potential changes in lake chemistry: no more 

than a 10 percent change in acid neutralizing capacity 

(ANC) for those water bodies where the existing ANC 

is at or above 25 microequivalents per liter (μeq/l) and 

no more than a 1 μeq/l change for those extremely 

sensitive water bodies where the existing ANC is below 

25 microequivalents per liter (μeq/l). No sensitive lakes 

were identified by either the NPS or FWS.

Since the proposed Alternative and cumulative air 

pollutant emission sources constitute many small 

sources spread out over a very large area, discrete 

visible plumes are not likely to impact the distant 

sensitive areas, but the potential for cumulative 

visibility impacts (increased regional haze) is a 

concern. Regional haze degradation is caused by fine 

particles and gases scattering and absorbing light. 

Potential changes to regional haze are calculated in 

terms of number of days with greater than a 

perceptible “just noticeable change” (1.0 deciview, or 

dv) in visibility when compared to background 

conditions. A 1.0 dv change is considered potentially 

significant in mandatory federal PSD Class I areas as 

described in the EPA Regional Haze Regulations 

(40 CFR 51.300 et seq.) and originally presented in 

Pitchford and Malm (1994). A 1.0 dv change is 

defined as about a 10 percent change in the extinction 

coefficient (corresponding to a 2 to 5 percent change 

in contrast, for a black target against a clear sky, at 

the most optically sensitive distance from an 

observer). This is a small but noticeable change in 

haziness under most circumstances when viewing 

scenes in mandatory federal Class I areas. However, 

the perceptibility threshold can be smaller or larger 

than this value depending on viewing conditions. 

For example, a 1.0 dv change is not a “just noticeable 

change” in all cases for all scenes. Visibility changes 

less than 1.0 dv are likely to be perceptible in some 

cases, especially where the scene being viewed is 

highly sensitive to small amounts of pollution, such 

as a site with preferential forward light scattering. 

Under other view-specific conditions, such as where 

the sight path to a scenic feature is less than the 

maximum visual range, a change greater than 1.0 dv 

might be required to be a “just noticeable change.”

This NEPA analysis is not designed to be a 

regulatory analysis conducted to Federal Land 

Manager (FLM) specifications nor is the analysis 

designed to predict specific visibility impacts for 

specific views in specific mandatory federal PSD 

Class I areas based on specific project designs. 

Rather, it is to characterize reasonably foreseeable 

visibility conditions that are representative of a fairly 
CHAPTER 4

Air Quality and Climate

4-24

broad geographic region, based on multiple 

assumptions regarding project and non-project source 

emissions. This approach is consistent with both the 

nature of regional haze and the requirements of 

NEPA. The modeling was conducted to identify areas 

that may require more detailed consideration when 

specific project-level permits are issued for CBNG 

development. At the time of a preconstruction air 

quality permit application, the applicable air quality 

regulatory agency may require a much more detailed 

visibility impact analysis. Factors such as the 

magnitude of dv change, frequency, time of the year

and the meteorological conditions during times when 

predicted visibility impacts are above the 1.0 dv 

threshold should all be considered when identifying 

areas for scrutinizing at the project-permitting level. 

The USFS, NPS and FWS have published their Final 

FLAG Phase I Report (Federal Register, Vol. 66 

No. 2, dated January 3, 2001), providing a consistent 

and predictable process for assessing the impacts of 

new and existing sources on AQRVs including 

visibility. For example, the FLAG report states, “A 

cumulative effects analysis of new growth (defined as 

all PSD increment-consuming sources) on visibility 

impairment should be performed,” and further, “If the 

visibility impairment from the proposed action, in 

combination with cumulative new source growth, is 

less than a change in extinction of 10 percent [1.0 dv] 

for all time periods, the FLMs will not likely object 

to the proposed action.”

Air Quality Modeling Assumptions: Near-field 

impacts refer to receptor points less than 50 km 

(31.25 miles) from the emissions source; far-field 

impacts are greater than 50 km from the source. 

When reviewing the modeled near- and far-field 

results, it is important to understand the assumptions 

made regarding potential resource development. In 

developing this analysis, there is uncertainty 

regarding ultimate development (i.e., number of 

wells, equipment to be used and specific locations) 

and so actual impacts may vary from the modeled 

values and would be affected by project permit 

conditions or stipulations. The modeling was based 

on the following assumptions: 

• Total predicted short-term air pollutant 

concentrations were assumed to be the sum of 

the assumed background concentration, plus the 

predicted maximum cumulative modeled 

concentrations (for comparison to national and 

state AAQS; background concentrations are not 

added to modeled concentrations for comparison 

to PSD increments), which may occur under 

different meteorological conditions. 

• Background air pollution concentrations were 

assumed to occur throughout the 20-year life of 

project at all locations in the region; even though 

this background was derived from monitoring 

primarily conducted in urban or industrial areas, 

rather than rural areas. The uniform background 

PM10 levels for each state are assumed to be 

representative of the background conditions for 

the entire modeled area of the PRB, based on 

monitoring data gathered throughout 

northeastern Wyoming and southeastern 

Montana.

• The maximum predicted air quality impacts 

occur only in the vicinity of the anticipated 

emission sources. Actual impacts would likely 

be less at distances beyond the predicted points 

of maximum impact.

• All emission sources were assumed to operate at 

their reasonably foreseeable maximum emission 

rates simultaneously throughout the life of 

project. Given the number of sources included in 

this analysis, the probability of such a scenario 

actually occurring over an entire year is very 

small.

• In developing the emissions inventory and 

model, there is uncertainty regarding ultimate 

development (i.e., number of wells, equipment to 

be used, specific locations, etc.) Most (90 

percent) proposed CBNG wells and 30 percent of 

conventional wells were assumed to be fully 

operational and remain operating (no shut-ins) 

throughout the life of project.

• The total proposed booster (field) and pipeline 

(sales) compression engines were assumed to 

operate at their rated capacities continuously 

throughout the life of project (no phased 

increases or reductions). In actual developments, 

compression equipment is expected to be added 

or removed incrementally as required by the well 

field operation, compressor engines would 

operate below full horsepower ratings and all 

compressor stations would not be operating at 

maximum levels simultaneously.

• The HAP analyses assumed a 9,900 horsepower, 

six-unit, reciprocating compressor engine station 

would operate at full load and at maximum 

emission levels continuously throughout the life 

of project. 

• The emissions inventory and model use peak 

years of construction and peak years of 

operations, which would not occur throughout 

the entire development region at the same time. 
CHAPTER 4

Air Quality and Climate

4-25

However, these conditions may occur in some 

areas.

• The emissions inventory and model assumed that 

an emission rate for compressor engines of 1.5 

grams per brake horsepower-hour (b/bhp-hr) of 

NOx. Since BACT is decided on a case-by-case 

basis, actual emission rates could be decided to 

be less or more than this level by the 

Departments of Environmental Quality in 

Wyoming or Montana and on Indian lands by 

EPA, for field and sales compressor engines. 

Actual NOx emission rates may range from 0.7 to 

2 b/bhp-hr. 

• There are no applicable local, state, tribal or 

federal acid deposition standards. In the absence 

of applicable standards, the acid deposition 

analysis assumed that a “limit of acceptable 

change” is: a 10 percent change in ANC for lakes 

with a background ANC greater than 25 μeq/l; or 

a 1 μeq/l change in ANC for lakes with a 

background ANC less than 25 μeq/l and would 

be a reasonably foreseeable significant adverse 

impact. Further, the atmospheric deposition 

impact analysis assumed no other ecosystem 

components would affect lake chemistry for a 

full year (assuming no chemical buffering due to 

interaction with vegetation or soil materials).

• The visibility impact analysis assumed that a 1.0 

dv “just noticeable change” would be a 

reasonably foreseeable significant adverse 

impact, although there are no applicable local, 

state, tribal or federal regulatory visibility 

standards. However, some FLMs are using 0.5 

dv as a screening threshold for significance.

• Mitigation measures are included in the 

emissions inventory and model that may not be 

achievable in all circumstances. However, actual 

mitigation decided by the developers and local 

and state authorities may be greater or less than 

those assumed in the analysis. For example, 

maintaining a construction road speed limit of 15 

mph may be reasonable in a construction zone 

but difficult to enforce elsewhere. Full (100 

percent) mitigation of fugitive dust from 

disturbed lands may not be achievable. Further, 

50 percent reduction in fugitive emissions is 

assumed based on construction road wetting on 

the unimproved access road to the pad and at the 

pad, but this level of effectiveness is 

characterized as the maximum possible. In the 

air quality modeling, no specific road wetting or 

other emissions were assumed to be used during 

the operations phase of the development (e.g., 

for maintenance vehicle traffic). However, 

during the review of proposed projects 

(applications for permit to drill [APDs]) the 

BLM would require specific mitigation measures

in certain areas during the operational phase of 

development.

• Induced or secondary growth related to increases 

in vehicle miles traveled (believed to be on the 

order of 10 percent overall) is not included in the 

emissions inventory and model. Not all fugitive 

dust emissions (including county and other 

collector roads) have been included in the 

emissions inventory and model. 

• Fugitive dust emissions from roads are treated as 

area sources rather than line sources in the 

model, which may thereby reduce or increase the 

predicted ambient concentrations at maximum 

concentration receptor points near the source, 

depending on the inputs to the model (e.g. 

meteorology, terrain). By not placing modeled 

receptors close to emission sources (e.g. wells 

and roads), the model may not capture higher 

ambient concentrations near these sources. A 

more refined, regulatory model may yield higher 

concentrations at locations near fugitive dust 

sources.

• For comparisons to the PSD Class I and II 

increments, the emissions inventory and model 

included only CBNG and reasonably forseeable 

future actions (RFFA) sources. Other existing 

increment consuming sources such as Campbell 

County coal mines were not included in this 

comparison, as the focus of the air quality 

analysis is on the proposed project and 

alternatives, and does not represent a regulatory 

PSD increment consumption analysis. A 

regulatory PSD increment consumption analysis 

needs to identify and consider all PSD increment 

consuming sources to determine the level of PSD 

Class II increment consumption. Additionally, a 

regulatory PSD increment analysis has to include 

all historic emission changes since the PSD 

trigger date, which extends back to 1978 for the 

area around Colstrip. Both increment expansion 

and consumption have occurred since that date. 

An analysis of this sort is beyond the scope of 

this project. MDEQ, in cooperation with the 

Northern Cheyenne Tribe and EPA, is 

conducting this type of analysis and the results 

will be factored into the new source review 

process in permitting additional CBNG sources 

in the study area.

• Monitoring data in Wyoming has indicated an 

upward trend in particulate matter concentrations 

in Campbell County since 1999, which coincides 
CHAPTER 4

Air Quality and Climate

4-26

with CBNG development but is also exacerbated 

by prolonged drought in the region. 

Given these assumptions, the model represents an 

estimate of potential air quality impacts in the project 

area and region.

It is important to note that before actual development 

could occur, the applicable air quality regulatory 

agencies (including the state, tribe, or EPA) would 

review specific air pollutant emissions 

preconstruction permit applications that examine 

potential project-wide air quality impacts for some 

categories of sources. As part of these permits

(depending on source size), the air quality regulatory 

agencies could require additional air quality impacts 

analyses or mitigation measures. Thus, before 

development occurs, additional site-specific air 

quality analyses would be performed to ensure 

protection of air quality. Emission sources that would 

violate standards would not be permitted.

Impacts from Management Common 

to All Alternatives

Air quality impacts would occur during construction 

(due to surface disturbance by earth-moving 

equipment, vehicle traffic fugitive dust, well testing

and drilling rig and vehicle engine exhaust) and 

production (including well production equipment and 

field and sales compression engine exhausts), as well 

as emissions associated with secondary growth. The 

amount of air pollutant emissions during construction 

and production would be controlled by watering; 

applying chemical stabilizers, surface material or 

reseeded vegetation to disturbed soils; and by air 

pollutant emission limitations imposed by applicable 

oil and gas lease management agencies and air 

quality regulatory agencies. Actual air quality 

impacts depend on the amount, duration, location and

characteristics of potential emissions sources, as well 

as meteorological conditions (wind speed and 

direction, precipitation, etc.).

Impacts from Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

Impacts to air quality would be minimal under this 

alternative. Based on air quality modeling of 

potential near-field (direct, indirect and cumulative) 

air quality impacts (Argonne 2002), localized shortterm increases in CO, NOx, SO2 and PM10

concentrations could occur, but most maximum 

concentrations are expected to be below applicable 

state and National Ambient Air Quality Standards 

(NAAQS), as well as NAAQS PSD increments, as 

shown in Table 4-8. These results are for near-field 

modeling. Far-field modeling results were also found 

to be below NAAQS and PSD Increments

(Additional data on near and far-field modeling 

results are contained in the Air Appendix – Part 1). 

Alternative A project source emissions would not 

result in an increase in ANC change above 10 percent 

for any Class I areas in the modeling domain. For the 

sensitive Upper Frozen Lake, within the mandatory 

federal PSD Class I Bridger Wilderness Area, the 

predicted impact is an ANC change of 0.65 percent 

which equates to a 0.04 μeq/l change. This is below 

threshold level of 1.0 μeq/l.

Direct visibility impacts from Alternative A project 

source emissions are predicted to be limited to the 

Class II, Crow Reservation. Up to 2 days annually 

were predicted to have a greater than “just noticeable 

change based on Alternative A project source 

emissions only. The Alternative A sources are 

predicted to have no direct impact on visibility in the 

other Class I and Class II areas (as shown in 

Table 4-11, under the “Project Sources Only” 

column.) 

Cumulative Impacts

Given the extensive non-project emission sources 

located throughout the analysis region (including 

CBNG developments in the Wyoming section of the 

Powder River Basin), there is a potential for 

cumulative air quality impacts from Alternative A 

project sources and non-project sources to exceed 

applicable thresholds under Alternative A. Two 

receptor points south of the Spring Creek Coal Mine 

had a maximum near-field cumulative impact of 104 

μg/m3 for 24-hour PM10. When combined with the 

assumed background level of 105 μg/m3

, the total 

impact of 210 μg/m3 would exceed the 24-hour PM10

NAAQS of 150 μg/m3

. Note that the Alternative A 

project sources contribute a maximum of 1.8 μg/m3

, 

as shown in Table 4-9. (Note: The contributions from 

each source represent maximums and do not 

necessarily occur at the same location. Therefore the 

sum of the individual contributions will not always 

equal the cumulative totals.)

In addition, non-project sources have the potential to 

exceed the PSD Class I increment for 24-hour PM10

on the Northern Cheyenne Reservation, as well as the 

PSD Class II increment, near the maximum assumed 

development area (see Table 4-10). For the Northern 
CHAPTER 4

Air Quality and Climate

4-27

TABLE 4-8

ALTERNATIVE A—PROJECT SOURCES CRITERIA POLLUTANT IMPACTS

Pollutant

Averaging 

Time

Project 

Modeled 

Impact 

(μg/m3

) 

PSD 

Increments a

(μg/m3

) Class 

II

Montana 

Background 

(μg/m3) 

Total 

Impactb

(μg/m3) 

Montana 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 1.94 25 11 12.9 100 100

1-hour 20.6 n/a 117 138 566 n/a

SO2 Annual 0.27 20 16 16 60 80

24-hour 0.87 91 73 74 260 365

3-hour 1.54 512 291 293 n/a 1,300

1-hour 1.86 n/a 666 668 1,300 n/a

PM10 Annual 0.52 17 30 31 50 Revoked

24-hour 1.83 30 105 107 150 150

PM2.5 Annual 0.27 n/a 8 8 15 15

24-hour 0.97 n/a 20 21 35 35

CO 8-hour 29.78 n/a 6,600 6,630 10,000 10,000

1-hour 49.4 n/a 15,000 15,049 26,000 40,000

a PSD Increment is to be compared to the Project Modeled Impact.

b Total Impact is the sum of the Project Modeled Impact and Background values. 

n/a – not applicable

TABLE 4-9

ALTERNATIVE A POTENTIAL NAAQS/MAAQS EXCEEDANCES

Location Pollutant

Contributions (μg/m3)

Cumulative 

Total

NAAQS/ 

MAAQS

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Background

Near-Field PM10

24-hr 1.8 n/a 104 105 210 150/150

TABLE 4-10

ALTERNATIVE A POTENTIAL PSD INCREMENT EXCEEDANCES

Location Pollutant

Contributions (μg/m3) 

PSD Class I 

Increment

PSD Class 

II 

Increment

Project 

Sources 

Only

Project 

+ RFFA 

Sources

NonProject 

Sources

Cumulative 

Total

Northern Cheyenne 

Reservation

PM10

24-hr 0.5 n/a 8.4 8.7 8 n/a

Near-Field PM10

24-hr 1.8 n/a 104 105 n/a 30

n/a – not applicable
CHAPTER 4

Air Quality and Climate

4-28

Cheyenne Reservation the far-field analysis indicated 

a maximum increment level of 8.7 μg/m3 with the 

non-project sources contributing 8.4 μg/m3 and the 

Alternative A project sources contributing up to 0.5 

μg/m3. All NEPA analysis comparisons to PSD 

increments are intended to evaluate a threshold of 

concern and do not represent a regulatory PSD 

increment consumption analysis.

Given a minimal background ANC level for Upper 

Frozen Lake within the mandatory federal PSD Class 

I Bridger Wilderness Area (5.8 μeq/l), the predicted 

cumulative impact of 1.6 μeq/l change would exceed 

the threshold level of 1.0 μeq/l. Approximately 

2.5 percent of this change would be attributable to 

Alternative A project sources alone. It should be 

noted that the very low background ANC level is 

based on only four samples taken on 3 days between 

1997 and 2000.

Potential visibility impacts were predicted to occur 

from non-project sources alone in every sensitive 

area analyzed (see Table 4-11). The Alternative A 

project sources in themselves were predicted to have 

a negligible direct impact on these areas (exception is 

the Class II Crow Reservation). However, the 

cumulative analysis predicted an average daily 

visibility impact increase of approximately 1 day per 

year for some Class I sensitive areas. Of the 15 

mandatory federal PSD Class I areas analyzed, 

cumulative average annual impacts would occur at 

the Fitzpatrick Wilderness Area (up to 10 days per 

year); the Scapegoat Wilderness Area (up to 3 days 

per year); the Teton Wilderness Area (up to 10 days 

per year); the Washakie Wilderness Area (up to 15 

days per year); and Wind Cave National Park (up to 

28 days per year).

Up to 42 days annually were predicted to have a

greater than “just noticeable change” within the redesignated PSD Class I Northern Cheyenne 

Reservation based on cumulative impact. The 

Alternative A project sources are predicted to have 

no direct impact on visibility whereas the non-project 

sources are predicted to have an impact of up to 38 

days annually.

The maximum potential cumulative visibility impacts 

(Table 4-12) predicted at the PSD Class II Crow 

Reservation were 69 days per year with Alternative A 

project sources directly contributing up to 2 days per 

year and non-project sources contributing up to 61 

days per year. Fewer cumulative impacts were 

predicted at other PSD Class II sensitive receptors, 

including the Absaroka-Beartooth Wilderness Area 

(30 days per year), the Bighorn Canyon National

Recreation Area (23 days per year), the Cloud Peak 

Wilderness Area (30 days per year), Devils Tower 

National Monument (39 days per year) and Jewel 

Cave National Monument (32 days per year). The

Alternative A project sources contributed generally 1 

to 2 days per year to these cumulative totals. Note 

that visibility impacts are due to PM2.5, NO2 and SO2

emissions from project and non-project sources.

Crow Reservation

Given the proximity of proposed Alternative A 

emission sources near or on the Crow Reservation, it 

is understandable that several of the maximum air 

pollutant impacts would occur on tribal lands. All 

direct, indirect and cumulative impacts were 

predicted to comply with applicable air quality 

standards and increments. Additionally, the following 

potential visibility impacts were predicted to occur on 

the Crow Reservation: up to 2 days per year from 

Alternative A project sources directly; up to 61 days 

per year from non-project sources; and up to 69 days 

per year from all sources cumulatively.

Northern Cheyenne Reservation

Given the proximity of proposed Alternative A 

emission sources near or on the Northern Cheyenne 

Reservation, it is understandable that some of the 

maximum air pollutant impacts would occur on tribal 

lands. With the exception of a potential non-project 

and cumulative sources exceedance of the 24-hour 

PM10 Class I Increments, all direct, indirect and

cumulative impacts were predicted to comply with 

applicable air quality standards and increments. 

Additionally, the following potential visibility 

impacts were predicted to occur on the Northern 

Cheyenne Reservation: no increased haze days per 

year from Alternative A project sources directly; up 

to 38 days per year from non-project sources and up 

to 42 days per year from all sources cumulatively.

Potential Mitigation

Roads and well locations constructed on soils 

susceptible to wind erosion could be appropriately 

surfaced to reduce the amount of fugitive dust 

generated by traffic or other activities. Dust inhibitors 

(i.e., surfacing materials, non-saline dust 

suppressants, water, etc.) could be used as necessary 

on unpaved collector, local and resource roads, which 

present a fugitive dust problem. To further reduce 

fugitive dust, operators could establish and enforce 

speed limits (i.e., 15 miles per hour [mph]) on all 

project-required roads in and adjacent to the project 

area.
CHAPTER 4

Air Quality and Climate

4-29

TABLE 4-11

ALTERNATIVE A CLASS I AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr) 

Maximum 

Δdv1

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Badlands Wilderness Area 0 n/a 17 to 25 18 to 25 10.0

Bridger Wilderness Area 0 n/a 8 to 10 8 to 10 10.9

Fitzpatrick Wilderness Area 0 n/a 7 to 9 8 to 10 13.5

Fort Peck Reservation 0 n/a 1 to 2 2 to 2 6.0

Gates of the Mountains Wilderness Area 0 n/a 3 to 4 3 to 4 12.7

Grand Teton National Park 0 n/a 4 to 6 4 to 6 5.8

Northern Absaroka Wilderness Area 0 n/a 10 to 12 11 to 12 11.3

Northern Cheyenne Reservation 0 n/a 30 to 38 33 to 42 39.9

Red Rock Lakes Wilderness Area 0 n/a 0 to 1 0 to 1 2.3

Scapegoat Wilderness Area 0 n/a 2 to 2 2 to 3 8.2

Teton Wilderness Area 0 n/a 7 to 9 7 to 10 11.9

Theodore Roosevelt National Park (North Unit) 0 n/a 1 to 2 1 to 2 3.3

Theodore Roosevelt National Park (South Unit) 0 n/a 2 to 4 2 to 4 3.9

U.L. Bend Wilderness Area 0 n/a 5 to 5 5 to 6 23.7

Washakie Wilderness Area 0 n/a 11 to 14 12 to 15 20.

Wind Cave National Park 0 n/a 21 to 27 22 to 28 7.7

Yellowstone National Park 0 n/a 9 to 11 9 to 11 9.0

1

∆dv – change in deciview

TABLE 4-12

ALTERNATIVE A CLASS II AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum 

∆dv

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Absaroka Beartooth Wilderness Area 0 n/a 28 to 29 28 to 30 15.2

Agate Fossils Bed National Monument 0 n/a 10 to 15 10 to 15 10.4

Bighorn Canyon National Recreation Area 0 n/a 19 to 21 19 to 23 28.2

Black Elk Wilderness Area 0 n/a 20 to 26 20 to 26 8.4

Cloud Peak Wilderness Area 0 n/a 21 to 28 23 to 30 13.9

Crow Reservation 2 n/a 56 to 61 65 to 69 53.0

Devils Tower National Monument 0 n/a 24 to 38 26 to 39 9.7

Fort Belknap Reservation 0 n/a 60 to 61 61 to 61 23.6

Fort Laramie National Historic Site 0 n/a 13 to 17 13 to 17 14.4

Jewel Cave National Monument 0 n/a 24 to 31 24 to 32 11.0

Mount Rushmore National Memorial 0 n/a 17 to 22 17 to 22 7.5

Popo Agie Wilderness Area 0 n/a 8 to 10 8 to 10 11.9

Soldier Creek Wilderness Area 0 n/a 13 to 18 13 to 18 9.3
CHAPTER 4

Air Quality and Climate

4-30

Potential emission reduction measures (BLM 1999d) 

are available to further limit NOx and other pollutant 

emissions. The appropriate level of control would be 

determined and required by the applicable air quality 

regulatory agencies during the preconstruction permit 

process. Visibility impacts would be mitigated by 

reducing emissions of PM2.5, NO2 and SO2. 

Compressor emissions could be reduced by any of 

the following methods:

• Reduce Compression Requirements. Reduce

the need for life of project compression by 

limiting the need for field compressors.

• Electric Compression. Using electric-powered 

compressor motors in place of the typical natural 

gas-fired compressor engines could eliminate 

direct NOx emissions from compressor station 

locations.

• Best Available Control Technology (BACT).

MDEQ would probably require BACT for 

compressor engines. Compressor engines would 

have an average potential NOx emission rate of 

less than the 1.5 grams per horsepower per hour 

(b/bhp-hr) used in the modeling assessment.

Additional discussion of particulate and NOx emission 

mitigation measures is provided in the Air Quality 

Appendix – Part 1. Mitigation measures for particulate 

matter have also been included in the Air Quality 

Appendix of this FSEIS. Some of these measures have 

been incorporated as management features of the 

alternatives (see Table 2-1 and Table 2-2 in Chapter 2).

Conclusion

Future development activities must comply with 

applicable local, state, tribal and federal air quality 

laws, statutes, regulations, standards, increments and

implementation plans. Increases in air pollutant 

emissions would occur under Alternative A. Given 

the assumptions applied in this analysis, it is unlikely 

direct air quality impacts from Alternative A project 

sources would violate any local, state, tribal, or 

federal air quality standards. When combined with 

other non-project emission sources, the 24-hour PM10

PSD Class II increment and NAAQS was predicted 

to be exceeded near the Spring Creek Coal Mine. 

Additionally, the cumulative impact of Alternative A 

project and non-project sources were predicted to 

exceed the 24-hour PM10 PSD Class I increment at 

the Northern Cheyenne Reservation. Finally, 

cumulative air quality impacts were predicted to 

exceed: 1) atmospheric deposition thresholds in the 

very sensitive Upper Frozen Lake in the PSD Class I 

Bridger Wilderness Area; and 2) visibility impact 

thresholds in all sensitive federal PSD Class I and 

Class II areas. 

Alternative B—CBNG Development with 

Emphasis on Soil, Water, Air, Vegetation, 

Wildlife and Cultural Resources

There is the potential for direct air quality impacts to 

occur under this alternative. Based on air quality 

modeling of potential near-field (direct, indirect and

cumulative) air quality impacts (Argonne 2002), 

localized short-term increases in CO, NOx, SO2 and

PM10 concentrations could occur and some maximum 

concentrations are predicted to be above applicable 

state and NAAQS and PSD increments.

The modeled impacts from project sources are shown 

in Table 4-13. These results, which are all below the 

Montana Ambient Air Quality Standards (MAAQS), 

NAAQS and PSD increments, are for near-field 

modeling. Far-field modeling results for project 

sources are also below the MAAQS, NAAQS and 

PSD Increments. (Refer to “Project Sources Only” 

columns in the following tables.)

Alternative B project sources by themselves would 

not result in an increase in ANC change above 

10 percent for any Class I areas in the modeling 

domain. For the sensitive Upper Frozen Lake, within 

the mandatory federal PSD Class I Bridger 

Wilderness Area, the predicted impact is an ANC 

change of 3.3 percent, which equates to a 0.19 μeq/l 

change. This is below threshold level of 1.0 μeq/l.

Even without other development in the region, 

Alternative B project sources alone may impact

visibility within seven mandatory federal PSD Class I 

Areas. Impacts greater than a “just noticeable 

change” of 1.0 dv was predicted to average 3 days 

per year within the Washakie Wilderness Area 

(maximum 3.7 Δdv), 2 days per year within the 

Bridger, Fitzpatrick and North Absaroka Wilderness 

Areas (maximum 2.4, 2.3 and 3.6 Δdv, respectively

and 1 day per year within the Teton Wilderness Area, 

U.L. Bend Wilderness Area and Yellowstone 

National Park (maximum 2.1, 4.3 and 3.0 Δdv, 

respectively). Given their proximity to anticipated 

Alternative B project sources, average annual 

visibility changes were also predicted to occur on up 

to 33 days within the re-designated PSD Class I 

Northern Cheyenne Reservation (maximum 13.4 

Δdv).

For PSD Class II areas, Alternative B project sources 

were predicted to impact visibility of greater than 

1.0 dv on 9 days within the Bighorn Canyon National 
CHAPTER 4

Air Quality and Climate

4-31

TABLE 4-13

ALTERNATIVE B—PROJECT SOURCES CRITERIA POLLUTANT IMPACTS

Pollutant

Averaging 

Time

Project 

Modeled 

Impact 

(μg/m3

) 

PSD1

Increments 

Class II 

(μg/m3

) 

Montana 

Background 

(μg/m3) 

Total2

Impact 

(μg/m3) 

Montana 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 9.1 25 11 20.1 100 100

1-hour 99.7 n/a 117 217 566 n/a

SO2 Annual 0.66 20 16 17 60 80

24-hour 2.1 91 73 75 260 365

3-hour 3.5 512 291 295 n/a 1,300

1-hour 4.6 n/a 666 671 1,300 n/a

PM10 Annual 3.6 17 30 34 50 50

24-hour 12.1 30 105 117 150 150

PM2.5 Annual 1.4 n/a 8 9 15 15

24-hour 6.2 n/a 20 26 65 65

CO 8-hour 74.1 n/a 6,600 6,674 10,000 10,000

1-hour 109 n/a 15,000 15,109 26,000 40,000

1 PSD Increment is to be compared to the Project Modeled Impact.

2 Total Impact is the sum of the Project Modeled Impact and Background values. 

n/a – not applicable

Recreation Area (maximum 5.4 Δdv) and on up to 

61 days within the PSD Class II Crow Reservation

(maximum 21.5 Δdv). Less extensive potential direct 

visibility impacts were also predicted for the PSD 

Class II Absaroka-Beartooth Wilderness Area (up to 

2 days per year, max. 5.0 Δdv), Cloud Peak 

Wilderness Area (up to 6 days per year, max. 3.8 

Δdv), Popo Agie Wilderness Area (up to 2 days per 

year, max. 2.6 Δdv), Devils Tower National 

Monument (up to 1 day per year, max. 2.8 Δdv) and 

Fort Belknap Reservation (up to 1 day per year, max. 

4.1 Δdv).

Temporary Impacts

Based on modeling, the potential maximum 24-hour 

average PM10 concentration due to fugitive dust 

emissions from the largest construction site of the 

Montana Project (6-acre sales compressor station 

with a two-track road 480 m long and 12 m wide) 

was estimated to be about 57 μg/m3

, occurring about 

400 m away from the center of construction site and 

about 200 m from the road. Although the temporary, 

short-term impacts of fugitive dust emissions from a 

construction site are not usually subjected to the 

requirements of ambient air quality standards, the 

total PM10 concentration, including the contributions 

from the largest construction site of the Montana 

Project, was estimated and compared with applicable 

MAAQS and NAAQS. Adding the estimated 

potential maximum 24-hour average PM10

concentration increase of 57 μg/m3 to the background 

concentration of 105 μg/m3 would amount to a total 

concentration of about 162 μg/m3

, which is about 108 

percent of MAAQS. All other construction sites of 

the Montana Project would be smaller in size than the 

6-acre sales compressor station construction site and

therefore, potential PM10 concentration impacts at 

these smaller sites would be less.

In addition, it is anticipated temporary electrical 

generators would be used during construction of the 

compressor stations. The exact number of temporary 

natural gas and diesel generators for compressor 

stations cannot be predicted, but typical emission 

factors were used to estimate the near-field impacts 

from one temporary diesel generator. The potential 

ground-level concentrations resulting from operation 

of a temporary generator are as follows: CO 1-hour 

up to 403 μg/m3

, CO 8-hour up to 243 μg/m3; NO2

24-hour up to 7.5 μg/m3

; NO2 annual up to 5.3 μg/m3; 

PM2.5 3-hour up to 0.4 μg/m3

; PM2.5 annual up to 0.4 

μg/m3

; SO2 3-hour up to 0.4 μg/m3; SO2 24-hour up 

to 0.3 μg/m3

; and SO2 annual up to 0.013 μg/m3. All 

concentrations are well below the ambient air quality 

standards.
CHAPTER 4

Air Quality and Climate

4-32

The HAP impact analysis was based on a maximum 

assumed six-unit reciprocating compressor engine 

station as described in the Air Quality Appendix. 

Since neither the MDEQ nor EPA have established

HAP standards, predicted 8-hour HAP concentrations 

were compared to a range of 8-hour state maximum 

Acceptable Ambient Concentration Levels (USEPA 

1997a). Formaldehyde was the only HAP predicted 

to exceed even the lowest threshold level. The 

maximum predicted cumulative 8-hour formaldehyde 

impact was 11.9 μg/m3

, which is within the threshold 

range of 4.5 μg/m3 (Pinnellas County Air Pollution 

Control Board, Florida) to 71 μg/m3 (State of 

Nevada, Division of Environmental Protection, Air 

Quality Control). The maximum formaldehyde 

concentration was predicted to occur at 85 meters 

(less than 300 feet) adjacent to a compressor station; 

as the distance from the emission source increases, 

the predicted concentrations decrease rapidly.

Analysis was conducted to determine the possible 

incremental cancer-risk over a 70 year lifetime for a 

most likely exposure (MLE) to residents and to a 

maximally exposed individual (MEI), such as 

compressor station workers. These cancer risks were 

calculated based on the maximum predicted annual 

concentrations, EPA’s unit risk factors for 

carcinogenic compounds (EPA 1997b) and an 

adjustment for time spent at home or on the job. This 

analysis assumed that residential exposure would be 

20 years (well over the national nine year average 

duration a family lives at a residence) and worker 

exposure would be 20 years (the full life of project). 

In addition, it was assumed that family members 

would be exposed to the maximum formaldehyde 

concentrations 64 percent of the day and to one 

fourth of this concentration for the remaining 36 

percent of the day.

The resulting incremental cancer risks were 

calculated to be 1.6 x 10-6 (MLE) and 2.2 x 10-6

(MEI). Both of these values fall near the lower end of 

the 1 to 100 x 10-6 threshold. The MLE and MEI 

cancer risks would fall below this threshold at 310 

and 460 meters away from the emission source, 

respectively. This distance would be even less for 

smaller compressors.

Cumulative Impacts

Given the non-project emission sources located 

throughout the analysis region, there is a potential for 

cumulative air quality impacts to exceed applicable 

thresholds under Alternative B. Two receptor points 

south of the Spring Creek Coal Mine had a maximum 

near-field cumulative impact of 107 μg/m3 for 24-hr 

PM10. When combined with the assumed background 

level of 105 μg/m3

, the total impact of 211 μg/m3

would exceed the 24-hour PM10 NAAQS of 

150 μg/m3

. The Alternative B project sources 

contribute a maximum 12.1 μg/m3 alone. The project 

sources combined with the RFFA (Reservation and 

Forest Service) developments contribute a total of 

13.1 μg/m3 and the non-project sources contributed 

104 μg/m3

. (Note: The contributions from each 

source represent maximums and do not necessarily 

occur at the same location. Therefore the sum of the 

individual contributions will not always equal the 

cumulative totals.)

Furthermore, a maximum near-field cumulative 

impact for 24-hour PM2.5 was determined to be 46 

μg/m3

. When combined with the assumed 

background level of 20 μg/m3

, the total impact of 66 

μg/m3 would exceed the 24-hour PM2.5 NAAQS of 

65 μg/m3

. Note that the Alternative B project sources 

contribute a maximum 6.2 μg/m3 alone. The project 

sources combined with the RFFA (Reservation and 

Forest Service) developments contribute a total of 6.9 

μg/m3 (see Table 4-14). 

In addition, Alternative B non-project sources have 

the potential to exceed the PSD Class I increment for 

24-hour PM10 on the Northern Cheyenne Reservation

and the Washakie Wilderness area. For the Northern 

Cheyenne Reservation the far-field analysis indicated 

a maximum increment level of 12.8 μg/m3 with the 

non-project sources contributing 8.4 μg/m3 and 

project sources contributing up to 4.2 μg/m3 alone. 

The project sources combined with the RFFA 

(Reservation and Forest Service) developments 

contribute a total of 5.9 μg/m3

. 

For the Washakie Wilderness Area the far-field 

analysis indicated a maximum increment level of 9.2 

μg/m3 with the non-project sources contributing 7.2 

μg/m3 and project sources contributing up to 1.4 

μg/m3 alone. The project sources combined with the 

RFFA (Reservation and Forest Service) 

developments contribute a total of 2.0 μg/m3

. 

Alternative B non-project sources also have the 

potential to exceed the PSD Class I increment for 

annual NO2 on the Northern Cheyenne Reservation

(see Table 4-15). The far-field analysis indicated a 

maximum increment level of 4.2 μg/m3 with the nonproject sources contributing 0.5 μg/m3 and project 

sources contributing up to 1.9 μg/m3 alone. The 

project sources combined with the RFFA 

(Reservation and Forest Service) developments 

contribute a total of 3.7 μg/m3

. 
CHAPTER 4

Air Quality and Climate

4-33

TABLE 4-14

ALTERNATIVE B POTENTIAL NAAQS/MAAQS EXCEEDANCES

Location Pollutant

Contributions (μg/m3) 

Cumulative 

Total NAAQS/ MAAQS

Project 

Sources 

Only

Project + 

RFFA 

Sources

NonProject 

Sources

Background

Near-Field PM2.5

24-hr 6.2 6.9 44.1 20 66 65/--- 

Near-Field

PM10

24-hr 12.1 13.1 104 105 212 150/150

TABLE 4-15

ALTERNATIVE B POTENTIAL PSD INCREMENTS EXCEEDANCES

Location Pollutant

Contributions (μg/m3)

PSD Class I 

Increment

PSD Class II 

Increment

Project 

Sources Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Northern 

Cheyenne 

Reservation

PM10

24-hr

4.2 5.9 8.4 12.8 8 n/a

Northern 

Cheyenne 

Reservation

NO2

Annual

1.9 3.7 0.5 4.2 2.5 n/a

Washakie 

Wilderness 

Area

PM10

24-hr

1.4 2.0 7.2 9.2 8 n/a

Near-Field PM10

24-hr

12.1 13.1 103.8 107 n/a 30

For Class II areas near the Spring Creek Coal Mine, 

the cumulative impact of 107 μg/m3 exceeds the 

Class II increment of 30 μg/m3 for 24-hour PM10. 

The non-project source contribution was predicted to 

be up to 104μg/m3 and the project source 

contribution was predicted to be up to 12.1 μg/m3

alone. The project sources combined with the RFFA 

(Reservation and Forest Service) developments 

contribute a total of 13.1 μg/m3

. 

All NEPA analysis comparisons to PSD increments 

are intended to evaluate a threshold of concern. They 

do not represent a regulatory PSD increment 

consumption analysis. 

Given a minimal background ANC level for Upper 

Frozen Lake within the mandatory federal PSD Class I 

Bridger Wilderness Area (5.8 μeq/l), the predicted 

cumulative impact of 1.8 μeq/l change would exceed the 

threshold level of 1.0 μeq/l. Approximately 11 percent 

of this change would be attributable to Alternative B 

project sources alone. Additionally, the potential 

cumulative impact of 10.4 μeq/l change would exceed 

the threshold level of 10 μeq/l for Florence Lake in the 

Class II Cloud Peak Wilderness Area.

Note that potential visibility impacts were predicted 

to occur from Alternative B non-project sources 

alone in every sensitive area analyzed. When 

Alternative B project sources are included in the 

cumulative analysis, average daily visibility impacts 

increase by 1 to 3 days per year at most areas, except 

the Northern Cheyenne Reservation and Class II 

Crow Reservation. Both are located near the potential 

Alternative B sources. 

Cumulative impacts from non-project, Alternative B 

and RFFA sources are likely to degrade visibility 

within fourteen of the fifteen mandatory federal PSD 

Class I Areas. When Alternative B project sources 

are combined with the RFFA (Reservation and Forest 

Service) developments cumulative impacts resulted 

in an increase of 1 to 5 days per year, as shown in the 

table below. The cumulative impacts ranged from a 

total of 2 to 32 days per year for these Class I areas 
CHAPTER 4

Air Quality and Climate

4-34

with a maximum ∆dv of 29.1 for the U.L. Bend 

Wilderness Area. 

Modeled project sources could impact seven of the 

PSD Class I Areas. A “just noticeable change” of 

1.0 dv was predicted to average 3 day per year within 

the Washakie Wilderness Area, 2 days per year 

within the Bridger, Fitzpatrick and North Absaroka 

Wilderness Areas and 1 day per year within the Teton 

Wilderness Area, U.L. Bend Wilderness Area and 

Yellowstone National Park (see Table 4-16). 

Given their proximity to anticipated Alternative B 

emission sources, cumulative average annual 

visibility changes were also predicted to occur on up 

to 92 days per year within the re-designated PSD 

Class I Northern Cheyenne Reservation. The 

maximum ∆dv was modeled to be 54.8. Project 

sources alone contributed up to 33 days per year. The 

project sources combined with the RFFA 

(Reservation and Forest Service) developments 

contribute a total of 60 days per year. Although no 

direct visibility impacts to the Fort Peck Reservation

may be attributable to Alternative B project sources, 

the cumulative impact was predicted to increase 3 

days per year with a maximum ∆dv of 7.4.

For PSD Class II areas, cumulative impacts from 

project sources combined with the RFFA 

(Reservation and Forest Service) sources and nonproject sources were predicted to be 11 days to 116 

days per year, as shown in Table 4-17 below with a 

maximum ∆dv of 66.9 (on Crow Reservation). The 

Alternative B project sources combined with RFFA 

sources contributed generally 1 to 55 days per year to 

these cumulative totals. Alternative B project source 

impacts were predicted to occur on 9 days within the 

Bighorn Canyon National Recreation Area and on up 

to 61 days within the PSD Class II Crow Reservation. 

Less extensive potential direct visibility impacts were 

also predicted for the PSD Class II AbsarokaBeartooth Wilderness Area (up to 9 days per year), 

Cloud Peak Wilderness Area (up to 6 days per year), 

Popo Agie Wilderness Area (up to 2 days per year), 

Devils Tower National Monument (up to 1 day per 

year) and Fort Belknap Reservation (up to 1 day per 

year). Note that visibility impacts are due to PM2.5, 

NO2 and SO2 emissions from project and non-project 

sources. 

TABLE 4-16

ALTERNATIVE B CLASS I AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum 

∆dv

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Badlands Wilderness Area 0 0 17 to 25 21 to 28 10.9

Bridger Wilderness Area 2 3 8 to 10 10 to 12 13.3

Fitzpatrick Wilderness Area 2 3 7 to 9 10 to 12 16.6

Fort Peck Reservation 0 1 1 to 2 4 to 5 7.4

Gates of the Mountains 

Wilderness Area

0 0 3 to 4 4 to 4 15.0

Grand Teton National Park 0 0 4 to 6 6 to 8 7.0

Northern Absaroka Wilderness 

Area

2 4 10 to 12 13 to 15 14.9

Northern Cheyenne Reservation 33 60 30 to 38 87 to 92 54.8

Red Rock Lakes Wilderness Area 0 0 0 to 1 2 to 3 2.9

Scapegoat Wilderness Area 0 0 2 to 2 3 to 3 9.9

Teton Wilderness Area 1 3 7 to 9 10 to 11 14.6

Theodore Roosevelt National Park

(North Unit) 0 0 1 to 2 2 to 3 3.7

Theodore Roosevelt National Park

(South Unit) 0 1 2 to 4 4 to 7 4.6

U.L. Bend Wilderness Area 1 1 5 to 5 6 to 8 29.1

Washakie Wilderness Area 3 5 11 to 14 16 to 18 24.8

Wind Cave National Park 0 0 21 to 27 25 to 32 9.1

Yellowstone National Park 1 3 9 to 11 12 to 13 12.8
CHAPTER 4

Air Quality and Climate

4-35

TABLE 4-17

ALTERNATIVE B CLASS II AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum 

∆dv

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Absaroka Beartooth Wilderness 

Area

2 4 28 to 29 32 to 33 21.5

Agate Fossils Bed National 

Monument 

0 0 10 to 15 14 to 19 12.8

Bighorn Canyon National 

Recreation Area 

9 17 19 to 21 32 to 34 34.0

Black Elk Wilderness Area 0 1 20 to 26 24 to 31 9.4

Cloud Peak Wilderness Area 6 10 21 to 28 35 to 39 16.3

Crow Reservation 61 75 56 to 61 113 to 116 66.9

Devils Tower National Monument 1 3 24 to 38 34 to 47 11.4

Fort Belknap Reservation 1 1 60 to 61 61 to 62 28.4

Fort Laramie National Historic 

Site

0 1 13 to 17 16 to 20 16.9

Jewel Cave National Monument 0 0 24 to 31 28 to 36 12.1

Mount Rushmore National 

Memorial

0 0 17 to 22 20 to 26 8.4

Popo Agie Wilderness Area 2 3 8 to 10 11 to 13 14.6

Soldier Creek Wilderness Area 0 0 13 to 18 16 to 21 11.4

Crow Reservation

Given the proximity of proposed Alternative B 

emission sources near or on the Crow Reservation, it 

is understandable that air pollutant impacts would 

occur on tribal lands. All direct, indirect and

cumulative impacts were predicted to comply with 

applicable air quality standards and increments. 

Additionally, the following potential visibility 

impacts were predicted to occur on the Crow 

Reservation: up to 61 days per year from 

Alternative B project sources directly; up to 75 days 

per year from project and RFFA sources; up to 61 

days per year from non-project sources; and up to 

116 days per year from all sources cumulatively. The 

maximum ∆dv was 66.9.

Northern Cheyenne Reservation

Given the proximity of proposed Alternative B 

emission sources near or on the Northern Cheyenne 

Reservation, it is understandable that some of the 

maximum air pollutant impacts could occur on tribal 

lands. With the exception of a potential non-project 

and cumulative source exceedance of the 24-hour 

PM10 and annual NO2 Class I Increments, all direct, 

indirect and cumulative impacts were predicted to 

comply with applicable air quality standards and 

increments. Additionally, the following potential 

visibility impacts were predicted to occur on the 

Northern Cheyenne Reservation: up to 33 days per 

year from Alternative B project sources directly; up 

to 60 days per year from project and RFFA sources; 

up to 38 days per year from non-project sources and 

up to 92 days per year from all sources cumulatively. 

The maximum ∆dv was 54.5.

Mitigation

Potential mitigation measures to further reduce 

potential air quality impacts from Alternative B 

sources would be the same as those presented for 

Alternative A sources above. 

Conclusion

Future development activities must comply with 

applicable local, state, tribal and federal air quality 

laws, statutes, regulations, standards, increments and

implementation plans. Increases in air pollutant 

emissions that could occur under Alternative B, 

resulting in direct air quality impacts would not be 

permitted. It is unlikely direct air quality impacts 
CHAPTER 4

Air Quality and Climate

4-36

from Alternative B project sources alone would 

violate local, state, tribal or federal air quality 

standards. 

When Alternative B project source impacts are 

combined with the RFFA (Reservation and Forest 

Service) sources and non-project sources, the 24-hour 

PM10 NAAQS and the 24-hour PM2.5 NAAQS were 

predicted to be exceeded near the Spring Creek Coal 

Mine. In addition, cumulative impact of Alternative 

B project, RFFA and non-project sources have the 

potential to exceed the PSD Class I increment for 24-

hour PM10 and PSD Class I Increment for annual 

NO2 on the Northern Cheyenne Reservation, as well 

as the PSD Class I increment for 24-hour PM10 on the 

Washakie Wilderness area. 

For Class II areas near the Spring Creek Coal Mine, 

the cumulative impact of 107 μg/m3 exceeds the 

Class II increment of 30 μg/m3 for 24-hour PM10. 

Finally, cumulative air quality impacts were 

predicted to exceed: 1) atmospheric deposition 

thresholds in the very sensitive Upper Frozen Lake in 

the PSD Class I Bridger Wilderness Area and in 

Florence Lake in the Class II Cloud Peak Wilderness 

Area; and 2) visibility impact thresholds in all PSD 

Class I and Class II area (including 15 mandatory 

federal PSD Class I areas) included in this analysis. 

Alternative C—Emphasize CBNG 

Development

Potential direct and cumulative air quality impacts 

are comparable to Alternative B.

Alternative D—Encourage CBNG 

Exploration and Development While 

Maintaining Existing Land Uses

Potential direct air quality impacts could occur under 

this alternative. Based on air quality modeling of 

potential near-field (direct, indirect and cumulative) 

air quality impacts (Argonne 2002), localized shortterm increases in CO, NOx, SO2 and PM10

concentrations could occur, but most maximum 

concentrations are expected to be below applicable 

state and NAAQS, as well as NAAQS PSD 

increments and some maximum concentrations are 

predicted to be above applicable state and NAAQS 

and PSD increments.

The modeled impacts from project sources only are 

shown in Table 4-18 below. These results, which are 

all below the MAAQS, NAAQS and PSD 

increments, are for near-field modeling. Far-field 

modeling results for project sources were also found 

to be below the MAAQS, NAAQS and PSD 

Increments. (Refer to “Project Sources Only” 

columns in the following tables.)

Alternative D project sources by themselves would 

not result in an increase in ANC change above 10 

percent for any Class I areas in the modeling domain. 

For the sensitive Upper Frozen Lake, within the 

mandatory federal PSD Class I Bridger Wilderness 

Area, the predicted impact is an ANC change of 1.8 

percent, which equates to a 0.1 μeq/l change. This is 

below threshold level of 1.0 μeq/l set as the level of 

significant impact.

Alternative D project sources by themselves are 

likely to directly degrade visibility within one 

mandatory federal PSD Class I Area. A greater than 

“just noticeable change” of 1.0 dv was predicted to 

average 1 day per year within the Washakie 

Wilderness Area (maximum 2 ∆dv) and up to 17 days 

within the re-designated PSD Class I Northern 

Cheyenne Reservation (maximum 8 ∆dv).

For PSD Class II areas, Alternative D project sources 

were predicted to impact visibility greater than 1.0 dv 

on 3 days within the Bighorn Canyon National 

Recreation Area (maximum 3 ∆dv), 1 day within the 

Cloud Peak Wilderness Area (maximum 2 ∆dv) and 

up to 42 days within the PSD Class II Crow 

Reservation (maximum 11 ∆dv). 

Temporary Impacts

Temporary impacts for Alternative D are expected to 

be comparable to those described under Alternative B.

Cumulative Impacts

Given the non-project emission sources located 

throughout the analysis region, there is a potential for 

cumulative air quality impacts to exceed applicable 

thresholds under Alternative D (see Table 4-19). Two 

receptor points south of the Spring Creek Coal Mine 

had a maximum near-field cumulative impact of 

106 μg/m3

. When combined with the assumed 

background level of 105 μg/m3

, the total impact of 

211 μg/m3 would exceed the 24-hour PM10 NAAQS 

of 150 μg/m3

. The Alternative D project source 

emissions would contribute a maximum of 10.8 

μg/m3 alone. The project and RFFA sources 

combined would contribute a maximum of 11.5 

μg/m3

. (Note: The contributions from each source 

represent maximums and do not necessarily occur at 

the same location. Therefore the sum of the 

individual contributions will not always equal the 

cumulative totals.)
CHAPTER 4

Air Quality and Climate

4-37

TABLE 4-18

ALTERNATIVE D—PROJECT SOURCES CRITERIA POLLUTANT IMPACTS

Pollutant

Averaging 

Time

Project 

Modeled 

Impact 

(μg/m3

) 

PSD 

Increments1

(μg/m3

) Class 

II

Montana 

Background 

(μg/m3) 

Total2

Impact 

(μg/m3) 

Montana 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 6.4 25 17.4 20.1 100 100

1-hour 49.5 n/a 167 217 566 n/a

SO2 Annual 0.65 20 16.7 17 60 80

24-hour 2.1 91 75.1 75 260 365

3-hour 3.5 512 295 295 n/a 1,300

1-hour 4.5 n/a 671 671 1,300 n/a

PM10 Annual 3.3 17 33.3 34 50 50

24-hour 10.8 30 116 117 150 150

PM2.5 Annual 1.2 n/a 9.2 9 15 15

24-hour 4.3 n/a 24.3 26 65 65

CO 8-hour 29.1 n/a 6,629 6,674 10,000 10,000

1-hour 47.6 n/a 15,048 15,109 26,000 40,000

1 PSD Increment is to be compared to the Project Modeled Impact.

2 Total Impact is the sum of the Project Modeled Impact and Background values. 

n/a – not applicable

TABLE 4-19

ALTERNATIVE D POTENTIAL PSD INCREMENTS EXCEEDANCES

Location Pollutant

Contributions (μg/m3)

Cumulative 

Total

NAAQS/ 

MAAQS

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources Background

Near-Field PM2.5

24-hr

4.3 4.7 44.1 20 65 65/--- 

Near-Field PM10

24-hr

10.8 11.5 103.8 105 211 150/150

na=not applicable

TABLE 4-20

ALTERNATIVE D POTENTIAL PSD INCREMENTS EXCEEDANCES

Location Pollutant

Contributions (μg/m3) 

PSD Class I 

Increment

PSD Class 

II 

Increment

Project 

Sources 

Only

Project 

+ RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Northern 

Cheyenne 

Reservation

PM10

24-hr

3.3 4.4 8.4 11.1 8 n/a

Washakie WSA PM10

24-hr

0.61 0.85 7.2 8.1 8 n/a

Near-Field PM10

24-hr

10.8 11.5 103.8 106.5 n/a 30
CHAPTER 4

Air Quality and Climate

4-38

Furthermore, a maximum near-field cumulative

impact for 24-hour PM2.5 was determined to be 45.3 

μg/m3

. When combined with the assumed 

background level of 20 μg/m3

, the total impact of 

65.3 μg/m3 would exceed the 24-hour PM2.5 NAAQS 

of 65 μg/m3

. Note that the Alternative D project 

sources contribute a maximum 4.3 μg/m3 alone. The 

project and RFFA sources combined contribute 4.7 

μg/m3

. 

In addition, Alternative D non-project sources have 

the potential to exceed the PSD Class I increment for 

24-hour PM10 on the Northern Cheyenne Reservation

(see Table 4-20). The far-field analysis indicated a 

maximum increment level of 9.8 μg/m3 with the nonproject sources contributing 8.4 μg/m3 and the project 

sources contributing up to 3.3 μg/m3 alone. The 

project and RFFA sources combined contribute 4.4 

μg/m3

. The far-field analysis also indicated a 

maximum cumulative increment level of 8.1 μg/m3

for the Washakie Wilderness Area. Non-project 

sources were determined to contribute 7.2 μg/m3 and 

the project sources contributing up to 0.61 μg/m3

alone. The project and RFFA sources combined 

contribute 0.85 μg/m3

. 

For Class II areas near the Spring Creek Coal Mine, 

the cumulative impact of 106 μg/m3 exceeds the 

Class II increment of 30 μg/m3 for 24-hour PM10. 

The non-project sources contribution was predicted 

to be up to 104 μg/m3 and the project sources 

contributions were predicted to be up to 10.8 μg/m3

alone. The project and RFFA sources combined 

contribute 11.5 μg/m3

. 

All NEPA analysis comparisons to PSD increments 

are intended to evaluate a threshold of concern. They 

do not represent a regulatory PSD Increment 

Consumption Analysis.

Given a minimal background ANC level for Upper 

Frozen Lake within the mandatory federal PSD Class 

I Bridger Wilderness Area (5.8 μeq/l), the predicted 

cumulative impact of 1.7 μeq/l change would exceed 

the threshold level of 1.0 μeq/l. Approximately 

6 percent of this change would be attributable to 

Alternative D project sources alone.

Note that potential visibility impacts were predicted 

to occur from Alternative D non-project sources 

alone in every sensitive area analyzed. When 

Alternative D project and RFFA sources are included 

in the cumulative analysis, the average daily visibility 

impacts increase by 1 to 2 days per year for thirteen 

of the fifteen areas as noted (see Table 4-21). The

maximum ∆dv was predicted to be 26.0 at the U.L. 

Bend Wilderness Area. Alternative D project sources 

alone are likely to directly degrade visibility within 

only one of the fifteen mandatory federal PSD Class I 

Areas. A change of 1.6 dv was predicted to average 1 

day per year within the Washakie Wilderness Area. 

For PSD Class II areas, Alternative D project source 

impacts were predicted to occur on up to 1 day within 

the Cloud Peak Wilderness Area (maximum 1.9 ∆dv) 

and up to 3 days within the Bighorn Canyon National 

Recreation Area (maximum 2.6 ∆dv). Cumulative 

impacts from project with RFFA sources and nonproject sources were predicted to be up to 35 days 

and 28 days per year, respectively. 

The Alternative D project sources with RFFA sources 

contributed generally 1 to 7 days per year to the 

cumulative totals for the Class II areas listed in 

Table 4-22. The maximum ∆dv was predicted to be 

30.6 at the Bighorn Canyon National Recreation Area

and 59.3 at the Crow Reservation. Note that visibility 

impacts are due to PM2.5, NO2 and SO2 emissions 

from project and non-project sources. 

Crow Reservation

Given the proximity of proposed Alternative D 

emission sources near or on the Crow Reservation, it is 

understandable that air pollutant impacts would occur 

on tribal lands. All direct, indirect and cumulative 

impacts were predicted to comply with applicable air 

quality standards and increments. Additionally, the 

following potential visibility impacts were predicted to 

occur on the Crow Reservation: up to 42 days per year 

from Alternative D project sources directly; up to 56 

days per year from project and RFFA sources 

combined; up to 61 days per year from non-project 

sources; and up to 105 days per year from all sources 

cumulatively. The maximum ∆dv was predicted to be 

59.3.

Northern Cheyenne Reservation

Given the proximity of proposed Alternative D 

emission sources near or on the Northern Cheyenne 

Reservation, it is understandable that air pollutant 

impacts would occur on tribal lands. With the 

exception of a potential non-project and cumulative 

source exceedance of the 24-hour PM10
CHAPTER 4

Air Quality and Climate

4-39

TABLE 4-21

ALTERNATIVE D CLASS I AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr) 

Maximum 

∆dv

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Badlands Wilderness Area 0 0 17 to 25 20 to 26 10.4

Bridger Wilderness Area 0 1 8 to 10 9 to 11 11.7

Fitzpatrick Wilderness Area 0 0 7 to 9 8 to 10 14.6

Fort Peck Reservation 0 0 1 to 2 2 to 3 6.5

Gates of the Mountains Wilderness Area 0 0 3 to 4 3 to 4 13.7

Grand Teton National Park 0 0 4 to 6 5 to 7 6.3

Northern Absaroka Wilderness Area 0 1 10 to 12 12 to 14 12.4

Northern Cheyenne Reservation 17 38 30 to 38 70 to 76 47.9

Red Rock Lakes Wilderness Area 0 0 0 to 1 1 to 2 2.6

Scapegoat Wilderness Area 0 0 2 to 2 2 to 3 8.9

Teton Wilderness Area 0 0 7 to 9 9 to 10 12.9

Theodore Roosevelt National Park

(North Unit)

0 0 1 to 2 1 to 2 3.5

Theodore Roosevelt National Park

(South Unit)

0 0 2 to 4 3 to 5 4.2

U.L. Bend Wilderness Area 0 0 5 to 5 5 to 6 26

Washakie Wilderness Area 1 1 11 to 14 14 to 16 21.9

Wind Cave National Park 0 0 21 to 27 23 to 29 8.2

Yellowstone National Park 0 0 9 to 11 11 to 12 10.5 

TABLE 4-22

ALTERNATIVE D CLASS II AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum 

∆dv

Project 

Sources 

Only

Project + 

RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Absaroka Beartooth Wilderness Area 0 1 28 to 29 30 to 31 17.8

Agate Fossils Bed National Monument 0 0 10 to 15 12 to 17 11.4

Bighorn Canyon National Recreation 

Area 

3 7 19 to 21 25 to 28 30.6

Black Elk Wilderness Area 0 0 20 to 26 22 to 28 8.8

Cloud Peak Wilderness Area 1 2 21 to 28 28 to 35 14.9

Crow Reservation 42 56 56 to 61 102 to 105 59.3

Devils Tower National Monument 0 0 24 to 38 29 to 42 10.3

Fort Belknap Reservation 0 0 60 to 61 61 to 61 25.5

Fort Laramie National Historic Sites 0 0 13 to 17 15 to 18 15.5

Jewel Cave National Monument 0 0 24 to 31 26 to 34 11.5

Mount Rushmore National Monument 0 0 17 to 22 18 to 23 7.9

Popo Agie Wilderness Area 0 1 8 to 10 9 to 11 12.9

Soldier Creek Wilderness Area 0 0 13 to 18 14 to 20 10.1
CHAPTER 4

Air Quality and Climate

4-40

Class I increments, all direct, indirect and cumulative 

impacts were predicted to comply with applicable air 

quality standards and increments. Additionally, the 

following potential visibility impacts were predicted to 

occur on the Northern Cheyenne Reservation: up to 17 

days per year from Alternative D project sources 

directly; up to 38 days per year from project and RFFA 

sources combined; up to 38 days per year from nonproject sources; and, up to 76 days per year from all 

sources cumulatively. The maximum ∆dv was 

predicted to be 47.9.

Mitigation

Potential mitigation measures to further reduce 

potential air quality impacts from Alternative D 

sources would be the same as those presented for 

Alternative A sources above.

Conclusion

Future development activities must comply with 

applicable local, state, tribal and federal air quality 

laws, statutes, regulations, standards, increments and

implementation plans. Increases in air pollutant 

emissions would occur under Alternative D. Given 

the assumptions applied in this analysis, it is unlikely 

direct air quality impacts from Alternative D project 

sources alone would violate any local, state, tribal, or 

federal air quality standards. 

When combined with Alternative D non-project 

sources and RFFA sources, the 24-hour PM10

NAAQS and 24-hour PM2.5 NAAQS was predicted to 

be exceeded near the Spring Creek Coal Mine. In 

addition, the cumulative impact from Alternative D 

project sources with RFFA sources and non-project 

sources have the potential to exceed the PSD Class I 

increment for 24-hour PM10 on the Northern 

Cheyenne Reservation. For Class II areas near the 

Spring Creek Coal Mine, the cumulative impact is 

predicted to exceed the Class II increment for 24-

hour PM10. 

Finally, cumulative air quality impacts were 

predicted to exceed: 1) atmospheric deposition 

thresholds in the very sensitive Upper Frozen Lake in 

the PSD Class I Bridger Wilderness Area; and 2) 

visibility impact thresholds in all PSD Class I and 

Class II areas (including 15 mandatory federal PSD 

Class I areas) included in this analysis. 

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts while 

Maintaining Existing Land Uses

Alternative E has been modeled in the FSEIS to allow 

direct comparison of the 2003 Final EIS preferred 

Alternative E to the new preferred Alternative H. The 

new air model was also used to predict impacts from 

Alternatives F and H. The new model incorporated an 

extended near-field receptor grid to include an 

expanded portion of the CBNG development area for 

both Montana and Wyoming, updated the emission 

inventories to the most currently available year (2004), 

added in the TRR as an RFFA and added emission 

sources identified by Environmental Defense Fund that 

were within the modeling domain. The new model also 

used three years of meteorological data initially to 

determine the meteorological year showing the highest 

impacts for the modeled base year (2004). The base 

year modeling indicated that meteorological year 2002 

predicted the highest impacts and was chosen as the 

meteorological year for modeling future alternatives 

development. Assumptions used in the Statewide EIS

for air emissions relating to CBNG development, as 

well as conventional oil and gas development, apply 

for the new modeling effort as well. 

Under the new model, predicted impacts for the base 

year indicated the potential for localized short-term 

increases in NOx, SO2, PM10 and PM2.5 

concentrations. However, maximum concentrations 

were predicted to be below applicable state and 

NAAQS, as well as PSD increments. The new model 

incorporated the emissions used for base year 

modeling and adjusted the emission factors for nonproject-related sources to account for changes to 

future emissions. This was done to allow a direct 

comparison of modeled impacts to applicable state 

and NAAQS, as well as PSD increments. Again, this 

was only done for comparative purposes; it does not 

constitute an effort to predict PSD increment 

consumption. In general, the base-year modeled 

impacts predicted ambient air concentrations that 

were higher than the monitored levels obtained for 

the year 2004. 

Most source groups were modeled separately and, in 

some cases, were added together in the postprocessing phase of modeling. This was done to 

provide a conservative estimate of impacts from 

various source groupings; in actuality, however, 

impacts were often at different receptors and 

occurred at different meteorological hours. A detailed 

description of the new model and predicted results 

are included in the Air Quality Appendix – Part 2. 

Based on air quality modeling of potential near-field 

(direct, indirect and cumulative) air quality impacts, 
CHAPTER 4

Air Quality and Climate

4-41

localized short-term increases in NOx, SO2, PM10 and

PM2.5 concentrations could occur, but most maximum 

concentrations are expected to be below applicable 

state and NAAQS, as well as PSD increments.

Additionally, the air quality permitting process would 

be used to analyze emission sources at the project 

level for CBNG development and to develop any 

needed mitigation. Emission sources that would 

violate standards would not be permitted by the 

agencies; therefore, residual impacts would remain 

within standards.

The modeled impacts from Montana CBNG sources 

only are shown in Table 4-23 below. These results for 

near-field modeling are all below the MAAQS, 

WAAQS and NAAQS; Far-field modeling results for 

project sources were also found to be below the 

MAAQS, NAAQS and most PSD increments. (Refer 

to “Project Sources Only” columns in the following 

tables.) The contributions from each source represent 

maximums and do not necessarily occur at the same 

location. Therefore, the sum of the individual 

contributions will not always equal the cumulative 

totals.

TABLE 4-23

ALTERNATIVE E PROJECT SOURCES CRITERIA POLLUTANT IMPACTS

Montana Impacts

Pollutant

Averaging 

Time

MT CBNG 

(Construction) 

Modeled 

Impact 

(μg/m3) 

MT CBNG 

(Operation) 

Modeled 

Impact 

(μg/m3) 

Montana

Base Year 

(All Sources) 

(μg/m3) 

PSD 

Increments1

(μg/m3) 

Class II 

Montana 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 0.46 3.60 3.91 25 100 100

1-hour 118.6 435 428 n/a 566 n/a

SO2 Annual 0.04 0.10 1.71 20 60 80

24-hour 0.56 0.98 15.1 91 260 365

3-hour 3.54 4.82 43.9 512 n/a 1,300

1-hour 10.57 11.51 140 n/a 1,300 n/a

PM10 Annual 0.25 1.43 3.52 17 n/a n/a

24-hour 3.33 12.9 30.6 30 150 150

PM2.5 Annual 0.01 0.20 0.88 n/a 15 15

24-hour 0.10 2.16 6.83 n/a 35 35

Wyoming Impacts

Pollutant

Averaging 

Time

MT CBNG 

(Construction) 

Modeled 

Impact 

(μg/m3) 

MT CBNG 

(Operation) 

Modeled 

Impact 

(μg/m3) 

Wyoming 

Base Year 

(All Sources) 

(μg/m3) 

PSD 

Increments1

(μg/m3) 

Class II

Wyoming 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 0.01 0.23 27.2 25 100 100

SO2 Annual 0.001 0.01 17 20 60 80

24-hour 0.01 0.06 124 91 260 365

3-hour 0.03 0.22 552 512 1,300 1,300

PM10 Annual 0.01 0.16 13.5 17 n/a n/a

24-hour 0.09 2.02 89.2 30 150 150

PM2.5 Annual 0.004 0.07 2.11 n/a 15 15

24-hour 0.04 1.10 9.4 n/a 35 35

1 PSD increment is to be compared to the Montana CBNG modeled impact. 

n/a – not applicable
CHAPTER 4

Air Quality and Climate

4-42

Alternative E project sources by themselves would 

not result in an increase in ANC change above 

10 percent for any Class I areas in the modeling 

domain. For the sensitive Upper Frozen Lake, within 

the mandatory federal PSD Class I Bridger

Wilderness Area, the predicted impact would be an 

ANC change of 133 percent, which equates to a 

2.6 μeq/l change. This is above the threshold level of 

1.0 μeq/l set as the level of significant impact.

However, this represents a 0.2 μeq/l change from the 

base year modeled impact of 2.4 μeq/l.

Using Visibility Method 2 indicates that Alternative E 

CBNG sources by themselves are likely to have an 

impact on visibility within ten mandatory federal PSD 

Class I Areas. A greater than “just noticeable change” 

of 1.0 dv was predicted to average up to 4 days per 

year within the Bridger Wilderness Area (maximum 

2.3 ∆dv), 3 days per year within the Fitzpatrick 

Wilderness Area (maximum 2.3 ∆dv), 1 day per year 

within the Fort Peck Reservation (maximum 1.4 ∆dv), 

6 days per year within the North Absaroka Wilderness 

Area (maximum 2.5 ∆dv), 2 days per year within the 

Teton Wilderness Area (maximum 1.2 ∆dv), 3 days 

per year within Theodore Roosevelt National Park 

(maximum 1.3 ∆dv), 6 days per year within the 

Washakie Wilderness Area (maximum 2.2 ∆dv), 1 day 

per year within Wind Cave National Park (maximum 

1.2 ∆dv), 2 days per year within Yellowstone National 

Park (maximum 2.4 ∆dv) and 235 days within the redesignated PSD Class I Northern Cheyenne 

Reservation (maximum 15.1 ∆dv). Using Visibility 

Method 6 to predict visibility impacts indicates that 

Alternative E project sources by themselves were 

predicted to have an impact on visibility within five 

mandatory federal PSD Class I areas. A greater than 

“just noticeable change” of 1.0 dv was predicted to 

average up to 1 day per year within the Fort Peck 

Reservation (maximum 1 ∆dv), 3 days per year 

within the North Absaroka Wilderness Area 

(maximum 1.5 ∆dv), 2 days per year within Theodore 

Roosevelt National Park (maximum 1.5 ∆dv), 1 day 

per year within the UL Bend Wilderness Area 

(maximum 1 ∆dv), 3 days per year within the 

Washakie Wilderness Area (maximum 1.2 ∆dv) and

1 day per year within Yellowstone National Park 

(maximum 1.3 ∆dv). Additionally, Alternative E 

project sources alone were predicted to impact 

visibility above 1.0 dv for 215 days within the 

designated PSD Class I Northern Cheyenne 

Reservation (maximum 13 ∆dv).

Alternative E project sources were predicted with 

Visibility Method 6 to impact visibility greater than 

1.0 dv on six PSD Class II areas. The model 

indicated up to 4 days per year within the Absaroka 

Beartooth Wilderness Area (maximum 3.3 ∆dv), 24 

days within the Bighorn Canyon National Recreation 

Area (maximum 3.5 ∆dv), 9 days per year within the 

Cloud Peak Wilderness Area (maximum 7.1 ∆dv), 

248 days per year within the Crow Reservation

(maximum 13.4 ∆dv), 2 days per year within the 

Devils Tower National Monument (maximum 1.1 

∆dv) and 4 days per year within the Wind River 

Reservation (maximum 1.3 ∆dv).

Hazardous Air Pollutant Impacts

Estimates of HAPs impacts were developed for both 

1-hour and annual near-field impacts for Montana 

CBNG sources. Results of the 1-hour modeled 

impacts for these modeling efforts were compared to 

the reference exposure levels (RELs) (EPA 1990).

Short-term impacts for the six analyzed compounds 

(benzene, ethyl benzene, formaldehyde, n-hexane, 

toluene and xylene) were compared to the RELs. 

Results showed that all impacts were well below the 

RELs, except for formaldehyde in the Wyoming 

near-field receptor grid. Impacts are approximately

50 percent of the established acute REL for 

formaldehyde for Alternative E. In Montana, the 

1-hour formaldehyde impact is approximately 

18 percent or less of the established acute REL.

Temporary Impacts

Temporary impacts for Alternative E are expected to

be comparable to those described under Alternative B.

Cumulative Impacts

Given the non-project emission sources located 

throughout the analysis region, there is a potential for 

cumulative air quality impacts to exceed applicable 

thresholds under Alternative E. However, none of the 

predicted impacts would exceed state or NAAQS. 

The maximum predicted 1-hour NO2 concentration 

for all sources combined for Montana near-field

receptors is 531 μg/m3 compared with a NAAQS of 

566 μg/m3. The base year maximum predicted impact 

for 1-hour NO2 concentrations from all sources 

combined is 428 μg/m3. Thus, predicted future-year 

impacts represent an increase of 24 percent. For 

existing Montana CBNG sources, the base year, 

1-hour NO2 concentration impacts would be 

122 μg/m3 for construction and 200 μg/m3 for 

operation. The maximum predicted impacts would be

118.6 μg/m3 and 435 μg/m3 for construction and 

operation, respectively. This indicates a slight 

decrease in ambient levels as construction declines 

and an increase of 117 percent from increased well 
CHAPTER 4

Air Quality and Climate

4-43

operation. The predicted 1-hour NO2 concentration 

from the TRR is 263 μg/m3, which is higher than the 

change due to combined Montana CBNG 

construction and operation. 

The maximum predicted base year impact to 

Wyoming near-field receptors for annual NO2

concentration from all sources combined is 

27.2 μg/m3. The future predicted impact is 

40.7 μg/m3, representing an increase of 50 percent. 

The Wyoming Ambient Air Quality Standards

(WAAQS)/NAAQS is 100 μg/m3. All modeled 

source groups’ annual NO2 impacts are below the 

WAAQS/NAAQS. However, the base year modeled 

impact exceeds the PSD Class II increment of 25 

μg/m3. Actual monitoring data for the base year are

significantly lower than base year model results, 

indicating the conservative nature of the model. 

The maximum model predicted base year 24-hour 

PM10 impact to Montana near-field receptors from all 

sources combined is 30.1 μg/m3. The future year 

impact from all combined sources is 45.5 μg/m3, or 

an increase of 51 percent. Again, the base year model 

results indicate an exceedance of the PSD Class II 

increment level (30 μg/m3), while actual monitored 

data are well below the PSD increment. The change 

from base year to future modeled year of 15.4 μg/m3

is below the PSD Class II increment level. For 

existing Montana CBNG sources, the base year 

predicted impact is 2.91 μg/m3 for construction and 

2.93 μg/m3 for operation. Future modeled impacts of 

3.33 μg/m3 and 12.9 μg/m3 indicate increases of 

14 percent due to construction and 340 percent for 

operation. The predicted 24-hour PM10 impacts from 

RFFA sources (TRR and Roundup Power Plant) are 

1.38 μg/m3 and 0.49 μg/m3, respectively.

All NEPA analysis comparisons to the PSD 

increments are intended to evaluate a threshold of 

concern and do not represent a regulatory PSD 

increment consumption analysis. 

The maximum predicted base year impact to 

Wyoming near-field receptors for 24-hour PM10

concentrations from all sources combined is 

89.2 μg/m3. The future predicted impact is 

105.8 μg/m3, representing an increase of 

18.6 percent. The WAAQS/NAAQS is 150 μg/m3. 

All modeled source groups’ 24-hour PM10 impacts 

are below the WAAQS/NAAQS. However, the base 

year modeled impact exceeds the PSD Class II 

increment of 30 μg/m3. The change from base year to 

future modeled year of 16.6 μg/m3 is below the PSD 

Class II increment. 

The maximum predicted 24-hour SO2 concentration 

for all sources combined for Montana near-field

receptors is 15.1 μg/m3, compared to an NAAQS of 

365 μg/m3. The base year maximum predicted impact 

for 24-hour SO2 concentration from all sources 

combined is 15.1 μg/m3. Thus, predicted future year 

impacts represent no change from the base year. For 

existing Montana CBNG sources, the base year 

24-hour SO2 concentration impacts are 0.45 μg/m3

for construction and 0.21 μg/m3 for operation. The 

maximum predicted impacts are 0.56 μg/m3 and 

0.98 μg/m3 for construction and operation, 

respectively. This indicates a slight change above the 

base year impacts. The predicted 24-hour SO2

concentration from the TRR is 3.08 μg/m3, which is 

higher than the change due to combined Montana 

CBNG construction and operation. The predicted 

24-hour SO2 concentration from the Roundup Power 

Plant is the same as for Montana CBNG construction.

The maximum predicted base year impacts to 

Wyoming near-field receptors for 24-hour SO2 and 

3-hour SO2 concentrations from all sources combined 

are 124 μg/m3 and 552 μg/m3. The future predicted 

impacts are unchanged from the base year. The base 

year modeled 24-hour SO2 and 3-hour SO2

concentration impacts exceed the PSD Class II 

increments of 91 μg/m3 and 512 μg/m3. 

In addition, Alternative E all sources combined has

the potential to exceed the PSD Class I increments 

for annual NO2 and 24-hour PM10 on the Northern 

Cheyenne Reservation (see Table 4-24). The far-field 

analysis indicated a maximum increment level of 

3.78 μg/m3 for annual NO2 and 10.9 μg/m3 for 24-

hour PM10. The annual NO2 level represents a change 

from the base year of 3.49 μg/m3, which is above the 

Class I PSD increment. However, the 

24-hour PM10 change over the base year is 

3.57 μg/m3, which is lower than the PSD increment. 

Additionally, the Alternative E all-Montana sources 

and Montana CBNG operation sources have the 

potential to exceed the PSD Class I increment for 

annual NO2 and 24-hour PM10 on the Northern 

Cheyenne Reservation. The impacts predicted from 

all Montana sources combined are 3.73 μg/m3 for 

annual NO2 and 9.73 μg/m3 for 24-hour PM10. 

Montana CBNG operation sources contribute 

3.57 μg/m3 to annual NO2 and 9.17 μg/m3 to 24-hour 

PM10. This is because in future year modeling the 

CBNG resource development for Indian owned land 

and Forestry Service managed land (RFFAs) was

included in the Montana CBNG source group. These 

high impacts are most likely due to RFFA 

development within the Northern Cheyenne 

Reservation and Custer National Forest. The 
CHAPTER 4

Air Quality and Climate

4-44

Fort Peck Reservation indicates a potential to exceed 

the Class I PSD increment for 24-hour SO2 of 5 

μg/m3, with all sources combined having a modeled 

impact of 7.02 μg/m3. The combined “other” source 

group category, containing mines, refineries and

various non-coal or oil and gas related sources, 

contributes 6.82 μg/m3 to this and is unchanged from 

the base year model. Similarly, Theodore Roosevelt 

National Park has the potential to exceed the Class I 

PSD increment for 3-hour and 24-hour SO2. Again, 

the other source group contributes over 99 percent to 

these totals, which are unchanged from the modeled 

base year. 

For Class II areas, the maximum cumulative impact 

from all combined sources of 45.8 μg/m3 on the 

Crow Reservation exceeds the Class II increment of 

30 μg/m3 for 24-hour PM10. The Montana coal 

sources’ contribution was predicted to be up to 44.8 

μg/m3, indicating CBNG sources contributions of 1.0 

μg/m3 alone. 

All NEPA analysis comparisons to the PSD 

increments are intended to evaluate a threshold of 

concern and do not represent a regulatory PSD 

increment consumption analysis. 

Given a minimal background ANC level for Upper 

Frozen Lake within the mandatory federal PSD Class 

I Bridger Wilderness Area (5.8 μeq/l), the predicted 

cumulative impact of 2.6 μeq/l change would exceed 

the threshold level of 1.0 μeq/l. The base year 

modeled background for Upper Frozen Lake was 2.4 

μeq/l, with CBNG related project activities 

contributing only 0.2 μeq/l to the cumulative impact 

of 2.6 μeq/l.

Potential visibility impacts were predicted to occur 

from Alternative E non-project sources alone in every 

sensitive area analyzed. When Alternative E project 

and RFFA sources are included in the cumulative 

analysis, the predicted visibility impacts show an 

increase of 23 days in the Northern Cheyenne 

Reservation (see Table 4-25). The maximum ∆dv was 

predicted to be 45.6 at the Bridger Wilderness Area. 

For PSD Class II areas, Alternative E Montana 

project plus RFFA source visibility impacts were 

predicted to occur in six sensitive areas. Cumulative 

impacts from Montana CBNG, combined with RFFA 

sources, added 8 days to the total days of predicted 

impacts to the Crow Reservation and 2 days to the 

Cloud Peak Wilderness Area. Non-project sources 

showed modeled visibility impacts at all Class II 

sensitive areas, with the maximum of 

365 days at the Crow Reservation. The Alternative E 

Montana CBNG sources, CBNG with RFFA sources

and non-project sources visibility impacts for the 

Class II areas are listed in Table 4-26. The maximum 

∆dv was predicted to be 57.8 at the Crow 

Reservation. 

TABLE 4-24

ALTERNATIVE E POTENTIAL PSD INCREMENTS EXCEEDANCES

Location Pollutant

Contributions (μg/m3) 

MT CBNG

Only

All 

Sources

Base Year

All Sources

PSD Class I 

Increment

PSD Class II 

Increment

Northern 

Cheyenne 

Reservation

Annual NO2

24-hr PM10

3.57

9.17

3.78

10.9

0.123

0.229

2.5

8 

n/a

n/a

Fort Peck 

Reservation

24-hr SO2 0.0004 7.02 6.97 5 n/a

Theodore 

Roosevelt NP

3-hr SO2

24-hr SO2

0.0007

0.0002

36.6

10.9

36.5

10.9

30

5 

n/a

n/a

Crow 

Reservation

24-hr PM10 18.8 45.8 46.7 n/a 30

MT Near Field 24-hr PM10 12.9 45.5 30.6 n/a 30

WY Near Field Annual NO2

24-hr PM10

Annual PM10

3-hr SO2 

24-hr SO2

0.23

2.02

0.16

0.22

0.06

40.7

106

19.1

552

124

27.2

89.2

13.5

552

124

n/a

n/a

n/a

n/a

n/a

25

30

17

512

91

na=not applicable
CHAPTER 4

Air Quality and Climate

4-45

TABLE 4-25

ALTERNATIVE E CLASS I AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum 

∆dv

Montana 

CBNG 

Sources Only

Montana 

CBNG +RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Badlands Wilderness Area 0 0 1 to 90 219 23

Bob Marshall Wilderness Area 0 0 1 to 22 28 6 

Bridger Wilderness Area 0 0 1 to 70 146 45.6

Fitzpatrick Wilderness Area 0 0 1 to 43 109 31.8

Fort Peck Reservation 1 1 1 to 16 92 16.9

Gates of the Mountains 

Wilderness Area

0 0 12 to 40 69 11.8

Grand Teton National Park 0 0 2 to 32 92 18.2

Northern Absaroka Wilderness 

Area

3 3 1 to 34 90 25.6

Northern Cheyenne 

Reservation

215 238 2 to 59 325 33.8

Red Rock Lakes Wilderness 

Area

0 0 1 to 19 50 9.4

Scapegoat Wilderness Area 0 0 5 to 31 48 11.3

Teton Wilderness Area 0 0 1 to 32 92 26.8

Theodore Roosevelt National

Park 

2 2 1 to 32 172 35.6

U.L. Bend Wilderness Area 1 1 5 to 47 99 15.4

Washakie Wilderness Area 3 3 1 to 38 115 36.8

Wind Cave National Park 0 0 1 to 122 262 27.5

Yellowstone National Park 1 1 2 to 38 105 22.6

Note: Visibility impacts were determined using Method 6 with monthly f(RH) values

Crow Reservation

Given the proximity of proposed Alternative E emission 

sources, either near or on the Crow Reservation, it is 

understandable that air pollutant impacts would occur on 

tribal lands. All direct, indirect and cumulative impacts 

were predicted to be in compliance with applicable air 

quality standards and increments, except the 24-hour 

PM10 Class II increment. Additionally, the following 

potential visibility impacts were predicted to occur on the 

Crow Reservation: up to 248 days per year from 

Alternative E CBNG sources directly; up to 256 days per 

year from project and RFFA sources combined; up to 

359 days per year from non-project sources; and up to 

365 days per year from all sources cumulatively. The 

maximum ∆dv was predicted to be 57.8. 

Northern Cheyenne Reservation

Given the proximity of proposed Alternative E 

emission sources, either near or on the Northern 

Cheyenne Reservation, it is understandable that air 

pollutant impacts would occur on tribal lands. With the 

exception of potential Montana CBNG and cumulative 

source exceedance of the annual NO2 and 24-hour PM10

Class I Increments, all direct, indirect and cumulative 

impacts were predicted to in compliance with applicable 

air quality standards and increments. Using Method 6, 

the following potential visibility impacts were predicted 

using Method 6 to occur on the Northern Cheyenne 

Reservation: up to 215 days per year from 

Alternative E Montana CBNG sources directly; up to 

238 days per year from Montana CBNG and RFFA 

sources combined; up to 59 days per year from nonproject sources; and, up to 219 days per year from all 
CHAPTER 4

Air Quality and Climate

4-46

TABLE 4-26

ALTERNATIVE E CLASS II AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions to Visibility (No. of days >1.0 dv/yr)

Maximum 

∆dv

Montana 

CBNG

Sources 

Only

Montana 

CBNG 

+RFFA 

Sources

Non-Project 

Sources

Cumulative 

Total

Absaroka Beartooth Wilderness 

Area

4 4 1 to 74 137 30.3

Agate Fossils Bed National 

Monument 

0 1 9 to 9 237 39.9

Bighorn Canyon National 

Recreation Area

24 24 18 to 74 298 41.1

Black Elk Wilderness Area 0 0 18 to 18 233 27.0

Cloud Peak Wilderness Area 9 11 1 to 29 147 23.9

Crow Reservation 248 256 37 to 359 365 57.8

Devils Tower National Monument 2 2 1 to 20 279 27.8

Fort Belknap Reservation 0 0 5 to 50 92 14.3

Fort Laramie National Historic 

Site

0 0 7 to 7 249 53.7

Jedediah Smith Wilderness Area 0 0 19 to 19 96 17.4

Jewel Cave National Monument 0 0 19 to 19 252 29.3

Lee Metcalf Wilderness Area 0 0 10 to 79 114 15.3

Mount Naomi Wilderness Area 0 0 1 to 1 52 19.8

Mount Rushmore National 

Monument

0 0 14 to 14 221 26.2

Popo Agie Wilderness Area 0 0 4 to 14 137 50.2

Soldier Creek Wilderness Area 0 0 11 to 11 245 39.6

Westville Mountain Wilderness 

Area

0 0 0 to 0 40 16.1

Wind River Reservation 4 4 13 to 35 243 56.6 

Note: Visibility impacts were determined using Method 6 with monthly f(RH) values

sources cumulatively. The maximum ∆dv was predicted 

to be 23.

Mitigation

Potential mitigation measures to further reduce 

potential air quality impacts from Alternative E 

sources would be the same as those presented for 

Alternative A sources above. Mitigation measures 

used to reduce potential visibility impacts are 

discussed under Alternative H in this Chapter.

Alternative F—Phased Development 

Multiple Screens (High Range)

The potential direct air quality impacts that could 

occur under this alternative are nearly identical to 

those predicted under Alternative E. Extensive 

review of modeling results presented for Alternative 

E indicates that many predicted impacts come from 

existing emission sources within the model domain, 

or are due to RFFA or non-project emissions. 

Potential near-field (direct, indirect and cumulative) 

air quality impacts show that, while localized shortterm increases in NO2, SO2, PM10 and PM2.5

concentrations could occur, most maximum 

concentrations are expected to be below applicable 

state and NAAQS, as well as PSD increments. When 

compared to base year modeled impacts a few

maximum concentrations are predicted to be above 

applicable state and NAAQS and PSD increments, 

however, the change from base year to future 

modeled year is insignificant and considerably below 

NAAQS and PSD increments. Additionally, the air 

quality permitting process would be used to analyze 

emission sources at the project level for CBNG 
CHAPTER 4

Air Quality and Climate

4-47

development and institute any needed mitigation. 

Emission sources that would violate standards would 

not be permitted by the agencies; therefore, residual 

impacts would remain within standards.

CALPOST Visibility Method 6 was used to predict 

visibility impacts under Alternative F, which 

indicated project sources alone would likely have an 

impact on visibility within four mandatory federal 

PSD Class I areas. A greater than “just noticeable 

change” of 1.0 dv was predicted to average up to 

3 days per year within the North Absaroka 

Wilderness Area (maximum 1.4 ∆dv), 2 days per year 

within Theodore Roosevelt National Park (maximum 

1.4 ∆dv), 3 days per year within the Washakie 

Wilderness Area (maximum 1.1 ∆dv) and 1 day per 

year within Yellowstone National Park (maximum 

1.2 ∆dv). Additionally, Alternative F project sources 

alone were predicted to impact visibility above 1.0 dv 

for 214 days within the re-designated PSD Class I 

Northern Cheyenne Reservation (maximum 12.5 

∆dv).

Visibility Method 6 was used to predict Alternative F 

project sources that would impact visibility greater 

than 1.0 dv on six PSD Class II areas. The model 

indicated up to 3 days per year within the Absaroka 

Beartooth Wilderness Area (maximum 3.1 ∆dv), 

18 days per year within the Bighorn Canyon 

National Recreation Area (maximum 3.1 ∆dv), 

8 days per year within the Cloud Peak Wilderness 

Area (maximum 6.8 ∆dv), 115 days per year within 

the Crow Reservation (maximum 12.9 ∆dv), 

1 day per year within the Devils Tower National 

Monument (maximum 1 ∆dv) and 3 days per year 

within the Wind River Reservation (maximum 1.2 

∆dv).

Because of the conditions for development within the 

crucial sage-grouse habitat areas, a lower level of 

development would likely occur over approximately 

93,529 acres (93,529 acres represents 12.8 percent of 

the potential CBNG development area within the 

Powder River Basin), which constitutes the area of 

the four identified crucial sage-grouse habitat areas. 

This lower level of development could result in an 

overall reduction of approximately 12.8 percent in 

CBNG related air emissions and associated impacts. 

Decreases in CBNG related air emissions and 

associated impacts would likely be higher within and 

locally around the four identified crucial sage-grouse 

habitat areas. The actual decrease in CBNG related 

air emissions and associated impacts would depend

on the level of development that might take place 

within the four crucial sage-grouse habitat areas.

The modeled impacts from CBNG sources only are 

shown in Table 4-27. 

Temporary Impacts

Temporary impacts for Alternative F are expected to 

be comparable to those described under Alternative E.

Cumulative Impacts

Given the non-project emission sources located 

throughout the analysis region, there is a potential for 

cumulative air quality impacts to exceed applicable 

thresholds under Alternative F. However, none of the 

model predicted impacts would exceed state or 

NAAQS. As discussed for Alternative E and as 

presented in Table 4-24, impacts for Alternative F 

could exceed PSD Class I and Class II increments. 

The impacts that could exceed PSD increments are 

generally due to existing RFFA or non-project 

sources, as described under Alternative E. All NEPA 

analysis comparisons to the PSD increments are 

intended to evaluate a threshold of concern and do 

not represent a regulatory PSD increment 

consumption analysis. 

Potential visibility impacts were predicted to occur 

from Alternative F non-project sources alone in every 

sensitive area analyzed. Alternative F project and 

RFFA sources are combined in the cumulative 

analysis, with the predicted visibility impacts 

showing a change of an increase of 23 days in the 

Northern Cheyenne Reservation (see 

Table 4-28). The maximum ∆dv was predicted to be 

45.6 at the Bridger Wilderness Area. 

For PSD Class II areas, Alternative F Montana 

project and RFFA source visibility impacts were 

predicted to occur in six sensitive areas. Cumulative 

impacts from Montana CBNG combined with RFFA 

sources added 8 days to the total days of predicted 

impacts to the Crow Reservation and 2 days to the 

Cloud Peak Wilderness Area. Non-project sources 

showed modeled visibility impacts at all Class II 

sensitive areas, with the maximum of 

365 days at the Crow Reservation. The Alternative F 

Montana CBNG sources, CBNG with RFFA sources

and non-project sources visibility impacts for the 

Class II areas are listed in Table 4-29. The maximum 

∆dv was predicted to be 57.7 at the Crow 

Reservation. 

Crow Reservation

Alternative F emission sources near or on the 

Crow Reservation would lead to potential air pollutant 
CHAPTER 4

Air Quality and Climate

4-48

TABLE 4-27

ALTERNATIVE F—PROJECT SOURCES CRITERIA POLLUTANT IMPACTS

Montana Impacts

Pollutant

Averaging 

Time

MT CBNG 

(Construction) 

Modeled 

Impact 

(μg/m3) 

MT CBNG 

(Operation) 

Modeled 

Impact 

(μg/m3) 

Montana

Base Year 

(μg/m3) 

PSD 

Increments1

(μg/m3) 

Class II

Montana 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 0.26 3.59 3.91 25 100 100

1-hour 67 435 428 n/a 566 n/a

SO2 Annual 0.02 0.10 1.71 20 60 80

24-hour 0.35 0.97 15.1 91 260 365

3-hour 2.08 4.82 43.9 512 n/a 1,300

1-hour 6.05 11.51 140 n/a 1,300 n/a

PM10 Annual 0.15 1.43 3.52 17 n/a n/a

24-hour 2.03 12.87 30.6 30 150 150

PM2.5 Annual 0.01 0.20 0.88 n/a 15 15

24-hour 0.20 2.16 6.83 n/a 35 35

Wyoming Impacts

Pollutant

Averaging 

Time

MT CBNG 

(Construction) 

Modeled 

Impact 

(μg/m3) 

MT CBNG 

(Operation) 

Modeled 

Impact 

(μg/m3) 

Wyoming 

Base Year 

(μg/m3) 

PSD 

Increments1

(μg/m3) 

Class II

Wyoming 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 0.014 0.23 27.2 25 100 100

SO2 Annual 0.128 1.93 17 20 60 80

24-hour 0.013 0.15 124 91 260 365

3-hour 0.054 1.04 552 512 1,300 1,300

PM10 Annual 0.003 0.06 13.5 17 n/a n/a

24-hour 0.072 0.22 89.2 30 150 150

PM2.5 Annual 0.014 0.06 2.11 n/a 15 15

24-hour 0.002 0.01 9.4 n/a 35 35

1 PSD Increment is to be compared to the Montana CBNG Modeled Impact.

n/a – not applicable
CHAPTER 4

Air Quality and Climate

4-49

TABLE 4-28

ALTERNATIVE F CLASS I AREA POTENTIAL VISIBILITY IMPACTS

Contributions Visibility (No. of days >1.0 dv/yr)

Location

Montana CBNG

Sources Only

Montana CBNG 

+RFFA Sources

Non-Project 

Sources

Cumulative 

Total

Maximum

∆dv

Badlands Wilderness Area 0 0 1 to 90 219 23

Bob Marshall Wilderness Area 0 0 1 to 22 28 6

Bridger Wilderness Area 0 0 1 to 70 146 45.6

Fitzpatrick Wilderness Area 0 0 1 to 43 109 31.8

Fort Peck Reservation 0 0 1 to 16 91 16.9

Gates of the Mountain Wilderness Area 0 0 12 to 40 69 11.8

Grand Teton National Park 0 0 2 to 32 92 18.2

Northern Absaroka Wilderness Area 3 3 1 to 34 90 25.5

Northern Cheyenne Reservation 214 237 2 to 59 328 33.8

Red Rock Lakes Wilderness Area 0 0 1 to 19 50 9.4

Scapegoat Wilderness Area 0 0 5 to 31 48 11.3

Teton Wilderness Area 0 0 1 to 32 92 26.7

Theodore Roosevelt National Park 2 2 1 to 32 172 35.6

U.L. Bend Wilderness Area 0 0 5 to 47 97 15.3

Washakie Wilderness Area 3 3 1 to 38 115 36.8

Wind Cave National Park 0 0 1 to 122 262 27.5

Yellowstone National Park 1 1 2 to 38 105 22.5

 Note: Visibility impacts were determined using Method 6 with monthly f(RH) values

TABLE 4-29

ALTERNATIVE F CLASS II AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum ∆dv

Montana 

CBNG

Sources Only

Montana CBNG 

+RFFA Sources

Non-Project 

Sources

Cumulative 

Total

Absaroka Beartooth Wilderness Area 3 3 1 to 74 137 30.2

Agate Fossils Bed National Monument 0 0 4 to 134 237 39.9

Bighorn Canyon National Recreation Area 18 18 4 to 129 298 40.9

Black Elk Wilderness Area 0 0 1 to 94 233 27

Cloud Peak Wilderness Area 8 10 1 to 52 146 23.9

Crow Reservation 115 123 13 to 359 365 57.7

Devils Tower National Monument 1 1 1 to 97 279 27.8

Fort Belknap Reservation 0 0 5 to 50 92 14.3

Fort Laramie National Historic Site 0 0 1 to 145 249 53.7

Jedediah Smith Wilderness Area 0 0 3 to 31 95 17.4

Jewel Cave National Monument 0 0 1 to 109 252 29.3

Lee Metcalf Wilderness Area 0 0 1 to 79 114 15.2

Mount Naomi Wilderness Area 0 0 1 to 25 52 19.8

Mount Rushmore National Monument 0 0 1 to 91 221 26.2

Popo Agie Wilderness Area 0 0 1 to 66 137 50.2

Soldier Creek Wilderness Area 0 0 4 to 142 245 39.6

Westville Mountain Wilderness Area 0 0 2 to 12 40 16.1

Wind River Reservation 3 3 4 to 96 243 56.5

Note: Visibility impacts were determined using Method 6 with monthly f(RH) values
CHAPTER 4

Air Quality and Climate

4-50

impacts on tribal lands. All direct, indirect and

cumulative impacts were predicted to be in compliance 

with applicable air quality standards and increments, 

with the exception of the 24-hour PM10 PSD Class II 

increment, which was shown under Alternative E to be 

due to a coal source and not project-related.

Additionally, the following potential visibility impacts 

were predicted to occur on the Crow Reservation: up 

to 257 days per year from Alternative F Montana 

CBNG sources directly, up to 265 days per year from 

project and RFFA sources combined, up to 359 days 

per year from non-project sources and up to 365 days 

per year from all sources cumulatively. The maximum 

∆dv was predicted to be 57.8 (Table 4-29).

Northern Cheyenne Reservation

Given the proximity of proposed Alternative F 

emission sources near or on the Northern Cheyenne 

Reservation, it is understandable that air pollutant 

impacts would occur on tribal lands. With the 

exception of potential project and cumulative source 

exceedance of the annual NO2 and 24-hour PM10

Class I increments, all direct, indirect and cumulative 

impacts were predicted to be in compliance with 

applicable air quality standards and increments. 

Additionally, the following potential visibility 

impacts were predicted to occur on the Northern 

Cheyenne Reservation: up to 214 days per year from 

Alternative F Montana CBNG sources directly, up to 

237 days per year from project and RFFA sources 

combined, up to 59 days per year from non-project 

sources and up to 328 days per year from all sources 

cumulatively. The maximum ∆dv was predicted to be 

33.8 (Table 4-28).

Mitigation

Potential mitigation measures to further reduce 

potential air quality impacts from Alternative F 

sources would be the same as those presented for 

Alternative A sources above. Mitigation measures 

that could be used to reduce these potential impacts 

are discussed under Alternative H in this 

chapter.Alternative G—Low Range Phased CBNG 

Development

Potential direct air quality impacts are comparable to 

Alternative F, but would be reduced by 

approximately 65 percent (this reduction would not 

be directly linear due to variables such as 

photochemistry, well locations, etc.) The air quality 

permitting process would be used to analyze emission 

sources at the project level for CBNG development 

and develop any mitigation needed. Emission sources 

that would violate standards would not be permitted 

by the agencies; therefore, residual impacts would 

remain within standards. 

Cumulative Impacts

Given the non-project emission sources located 

throughout the model domain, there is a potential for 

cumulative air quality impacts to exceed applicable 

thresholds under Alternative G. While project-related

impacts would be reduced by approximately

65 percent, impacts for Alternative G would still have 

the potential to exceed PSD Class I and Class II 

increments. The impacts that have the potential to 

exceed PSD increments are generally due to existing, 

RFFA, or non-project sources, as described under 

Alternative E. As was previously described under 

Alternative E, base year modeled impacts show the 

potential to exceed PSD Class I and Class II 

increments even without considering project emission 

sources. The existing and non-project emission 

sources contributing to the base year impacts would 

be unchanged under Alternative G; thus the potential 

for exceeding PSD increments would be similar to 

that described for Alternative E. Additionally, certain 

RFFAs (TRR and Roundup Power Plant) would be 

the same under each alternative. Receptors near these 

emission sources would be affected similarly under 

each alternative, with project emission sources 

contributing only a small portion of the total.

Alternative H—Preferred Alternative - 

Multiple Screens

The potential direct air quality impacts that could 

occur under Alternative H were modeled using five 

different scenarios within the SAQA. The results 

presented here are from scenario 1 which represents 

the predicted model emissions that would result from 

the implementation of Alternative H and using 

current practices for the development of CBNG 

resources within the PRB of Montana. A review of 

modeling results indicates that many of the predicted 

emissions come from existing emission sources 

within the model domain, or are due to RFFA or nonproject emissions. Potential near-field (direct, indirect

and cumulative) air quality impacts show that 

localized short-term increases in NO2, SO2, PM10 and

PM2.5 concentrations could occur, but maximum 

concentrations are predicted to be below applicable 

state and NAAQS, as well as PSD increments. 

Using Visibility Method 6 to predict visibility 

impacts indicates that Alternative H project sources 

would not result in a “just noticeable change” to 

visibility of greater than 1.0 dv at any of the 

mandatory federal PSD Class I Areas evaluated 

within the modeling domain. Alternative H project 
CHAPTER 4

Air Quality and Climate

4-51

TABLE 4-30

ALTERNATIVE H (SCENARIO 1)—PROJECT SOURCES CRITERIA POLLUTANT IMPACTS

Montana Impacts

Pollutant

Averaging 

Time

MT CBNG 

(Construction) 

Modeled 

Impact 

(μg/m3) 

MT CBNG 

(Operation) 

Modeled 

Impact 

(μg/m3) 

Montana 

Base Year 

(μg/m3) 

PSD 

Increments1

(μg/m3) 

Class II

Montana 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 0.24 1.69 3.91 25 100 100

1-hour 33.1 251 428 n/a 566 n/a

SO2 Annual 0.024 0.007 1.71 20 60 80

24-hour 0.16 0.049 15.1 91 260 365

3-hour 0.94 0.28 43.9 512 n/a 1,300

1-hour 3.18 0.94 140 n/a 1,300 n/a

PM10 Annual 0.18 0.43 3.52 17 50 50

24-hour 1.13 2.9 30.6 30 150 150

PM2.5 Annual 0.052 0.21 0.88 n/a 15 15

24-hour 0.37 1.49 6.83 n/a 65 65

Wyoming Impacts

Pollutant

Averaging 

Time

MT CBNG 

(Construction) 

Modeled 

Impact 

(μg/m3) 

MT CBNG 

(Operation) 

Modeled 

Impact 

(μg/m3) 

Wyoming 

Base Year 

(μg/m3) 

PSD 

Increments1

(μg/m3) 

Class II

Wyoming 

AAQS 

(μg/m3) 

NAAQS 

(μg/m3) 

NO2 Annual 0.048 0.35 27.2 25 100 100

SO2 Annual 0.005 0.002 17 20 60 80

24-hour 0.03 0.009 124 91 260 365

3-hour 0.15 0.04 552 512 1,300 1,300

PM10 Annual 0.047 0.13 13.5 17 50 50

24-hour 0.28 0.93 89.2 30 150 150

PM2.5 Annual 0.017 0.082 2.11 n/a 15 15

24-hour 0.13 0.69 9.4 n/a 65 65

1 PSD Increment is to be compared to the Montana CBNG Modeled Impact. 

n/a – not applicable

sources were predicted to impact visibility above 

1.0 dv for 19 days within the designated PSD Class I 

Northern Cheyenne Reservation. 

Using Visibility Method 6 to predict visibility 

impacts indicates that Alternative H project sources 

would result in a “just noticeable change” to visibility 

of greater than 1.0 dv at four PSD Class II areas. The 

model results predict one day per year within the 

Absaroka Beartooth Wilderness Area, four days per 

year within the Bighorn Canyon National Recreation 

Area, four days per year within the Cloud Peak 

Wilderness Area, and 61 days per year within the 

Crow Reservation. 

The modeled impacts from project sources are shown 

in Table 4-30. 

Temporary Impacts

Temporary impacts for Alternative H would be less 

than those described under Alternative E due to 

implementation of the provisions within the Air 

Quality Screen.

Cumulative Impacts

Cumulative impacts under Alternative H (scenario 1) 

for the Montana near-field receptor grid indicate that 

there are no exceedances of air quality standards 
CHAPTER 4

Air Quality and Climate

4-52

predicted. The 1-hour NO2 ambient concentration for 

the All Montana source group is 539 μg/m3 and for 

the All Sources source group is 540 μg/m3. While the 

standard of 565 μg/m3 is not exceeded, the model 

predicted concentrations are close enough to the 

standard to indicate that there is a potential for this 

standard to be exceeded.

Crow Reservation

At the Crow Reservation, all direct, indirect and 

cumulative impacts are predicted to be below any 

applicable air quality standards.

Alternative H project sources were predicted to 

impact visibility above 1.0 dv for 61 days within the 

PSD Class II Crow Reservation. Up to 165 days of 

impacted visibility are predicted to occur from 

CBNG RFFA sources and up to 365 days of impacted 

visibility are predicted to occur from all sources 

cumulatively (Table 4-32).

Northern Cheyenne Reservation

At the Northern Cheyenne Reservation, all direct, 

indirect and cumulative impacts are predicted to be 

below any applicable air quality standards.

Alternative H project sources were predicted to 

impact visibility above 1.0 dv for 19 days within the 

designated PSD Class I Northern Cheyenne 

Reservation. Up to 136 days of impacted visibility 

are predicted to occur from CBNG RFFA sources 

and up to 337 days of impacted visibility are 

predicted to occur from all sources cumulatively 

(Table 4-31). 

TABLE 4-31

ALTERNATIVE H (SCENARIO 1) - CLASS I AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum 

∆dv

Montana 

CBNG 

Sources 

Only

Montana 

CBNG 

+RFFA 

Sources

Non-Project 

Sources

All Sources

Cumulative 

Total

Badlands Wilderness Area 0 0 1 to 90 218 12.5

Bob Marshall Wilderness Area 0 0 1 to 22 28 4.2

Bridger Wilderness Area 0 0 1 to 70 146 15.2

Fitzpatrick Wilderness Area 0 0 1 to 43 109 12.8

Fort Peck Reservation 0 0 1 to 16 90 8 

Gates of the Mountains Wilderness Area 0 0 12 to 40 69 9.1

Grand Teton National Park 0 0 2 to 32 92 7.6

Northern Absaroka Wilderness Area 0 0 1 to 34 90 12.5

Northern Cheyenne Reservation 19 136 2 to 59 337 15.5

Red Rock Lakes Wilderness Area 0 0 1 to 19 50 5.3

Scapegoat Wilderness Area 0 0 5 to 31 48 6.7

Teton Wilderness Area 0 0 1 to 32 92 11.9

Theodore Roosevelt National Park 0 0 1 to 32 170 13.6

U.L. Bend Wilderness Area 0 0 5 to 47 98 5.9

Washakie Wilderness Area 0 0 1 to 38 115 15.2

Wind Cave National Park 0 0 1 to 122 260 14.7

Yellowstone National Park 0 0 2 to 38 105 9.6

Note: Visibility impacts were determined using Method 6 with monthly f(RH) values
CHAPTER 4

Air Quality and Climate

4-53

TABLE 4-32

ALTERNATIVE H (SCENARIO 1) - CLASS II AREA POTENTIAL VISIBILITY IMPACTS

Location

Contributions Visibility (No. of days >1.0 dv/yr)

Maximum ∆dv

Montana 

CBNG 

Sources 

Only

Montana 

CBNG 

+RFFA 

Sources

Non-Project 

Sources

All Sources

Cumulative 

Total

Absaroka Beartooth Wilderness Area 1 1 1 to 74 136 12.5

Agate Fossils Bed National Monument 0 0 4 to 134 237 13.2

Bighorn Canyon National Recreation Area 4 7 4 to 129 313 63.9

Black Elk Wilderness Area 0 0 1 to 94 232 15

Cloud Peak Wilderness Area 4 4 1 to 52 145 17

Crow Reservation 61 165 13 to 359 365 66.5

Devils Tower National Monument 0 0 1 to 97 278 13.4

Fort Belknap Reservation 0 0 5 to 50 92 5.4

Fort Laramie National Historic Site 0 0 1 to 145 249 14.9

Jedediah Smith Wilderness Area 0 0 3 to 31 95 6.6

Jewel Cave National Monument 0 0 1 to 109 251 14.1

Lee Metcalf Wilderness Area 0 0 1 to 79 112 6.1

Mount Naomi Wilderness Area 0 0 1 to 25 52 7 

Mount Rushmore National Monument 0 0 1 to 91 220 14.7

Popo Agie Wilderness Area 0 0 1 to 66 137 16.3

Soldier Creek Wilderness Area 0 0 4 to 142 245 12.5

Westville Mountain Wilderness Area 0 0 2 to 12 40 5.6

Wind River Reservation 0 0 4 to 96 243 2.1

Note: Visibility impacts were determined using Method 6 with monthly f(RH) values

Mitigation

Potential mitigation measures to further reduce 

possible ambient air quality impacts from 

Alternative H sources would be the same as those 

presented for Alternative A sources. 

Modeled visibility impacts resulting from project 

CBNG sources do not show the potential to increase

the number of days with visibility impairment to 

mandatory Class I areas. Modeled visibility impacts 

resulting from project CBNG sources do show the 

potential to increase the number of days with 

visibility impairment at the designated Class I 

Northern Cheyenne Reservation and at the Class II 

Crow Reservation. Mitigation measures would be 

used to minimize these model predicted increases. In 

addition to the mitigation measures presented below, 

BLM would work with and assist cooperating 

agencies to perform visibility modeling studies in 

conjunction with monitoring conducted under 

Alternative H. The results of the monitoring and 

visibility modeling studies would be reviewed by the 

Air Quality Task Group. The Air Quality Task Group 

would also work with BLM to identify and select the 

appropriate party to perform the modeling studies. 

This might entail operator-funded, third-party 

contractors; BLM-funded agency or private 

contractors; or some other combination of funding 

sources. 

Mitigation measures that could be used to reduce 

potential visibility impacts include the following: 

• Reduce source emissions from drilling 

operations by minimizing the number of 

well pads through use of improved drilling 

technologies such as horizontal drilling, or 

other similar approaches that may become 

available during the expected CBNG 

development and operation duration. This 

would result in decreased emissions of 

particulate matter from well pad and road 
CHAPTER 4

Air Quality and Climate

4-54

construction during the construction and 

would reduce particulate matter emissions 

from travel along roads to well pads during 

the operation phase.

• Increasing spacing between well pads would 

cause a decrease in localized ambient 

impacts as well as reducing far-field effects 

to an extent.

• Requiring the use of best available control 

technology (BACT) for certain emission 

sources, such as compressor engines, would

reduce emissions. If BACT alone did not 

provide sufficient reduction in emissions to 

avoid visibility impacts, a requirement for 

the lowest achievable emissions rate 

(LAER) might become necessary for CBNG 

development in areas with visibility impact 

concerns. As an example, LAER for 

compressors could involve use of electric 

powered compressor engines. 

• Use of alternate fuels such as low sulfur and 

low nitrogen content fuels would minimize 

NOx and SO2 formation. 

• Alternative H has a feedback loop where the 

effectiveness of each mitigation measure, or 

set of measures, is quantified through 

monitoring and modeling. As monitoring 

and modeling results become available, 

BLM might adopt more stringent measures 

to avoid predicted air quality impacts. BLM 

would provide CBNG operators with a 

target of no exceedances of ambient air 

quality standards and a list of possible 

mitigation measures to minimize impacts to 

visibility. Operators would then design 

projects with selected mitigation measures. 

Alternative H’s adaptive management 

approach would allow BLM to accept the 

proposals and retroactively apply successful 

mitigation measures to existing projects, as 

needed. While DEQ would play a lead role 

in ongoing air quality monitoring and 

modeling, BLM would support it in 

performing any additional work that might

be required to meet Alternative H objectives 

of no exceedances.

The following mitigation measures were 

discussed in Chapter 2 as part of the description 

of the Air Quality Screen of Alternative H.

• The number of wells connected to each 

compressor would be maximized and

natural-gas-fired or electrical compressors or 

generators would be required. 

• To reduce dust, operators of federal leases 

would have to post and enforce speed limits 

for their employees and contractors. 

Operators could work with local government 

to use dust suppression techniques on roads.

See additional mitigation measures in the 

Air Quality and Climate Appendix.

• If subsequent visibility modeling conducted 

as part of the air screen indicates 

unacceptable impacts would occur at a 

future point in the PRB development, 

modeling would then include mitigation 

scenarios that would investigate mitigation 

measures. Mitigation efforts would focus on 

compressor motors and the extent of 

operating compressors because it appears 

that gas-fired compressor motors account for 

approximately 90% of the overall project 

emissions and visibility impacts.

Supplemental Air Quality Analysis

The air analysis conducted for the DSEIS showed the 

potential for CBNG project-related activities to have 

an impact on air quality (particularly to visibility) at 

certain Class I areas within the planning area, 

including the Northern Cheyenne Reservation. The 

Supplemental Air Quality Analysis (SAQA) was 

conducted to determine at what level CBNG projectrelated development would have an impact on 

visibility at the Northern Cheyenne Reservation, as 

well as on other Class I areas within the planning 

area and to modify the preferred alternative to 

include monitoring, mitigation and avoidance of 

those potential impacts.

The SAQA contains data on five scenarios that were 

modeled for the planning area. The revised 

Alternative H scenario was modeled to better 

determine the direct impacts to air quality from 

project-related CBNG development. The first and 

second scenarios are modifications that reflect the 

differences in how current CBNG development is 

conducted within the Montana portion of the Powder 

River Basin versus what was predicted in the DSEIS. 

Two additional mitigation scenarios were modeled 

with data presented on impacts resulting from 

reduced compression requirements for project CBNG 

development under the first and second scenarios. 

The SAQA also contains a modification to the 

preferred alternative to allow for monitoring, 

mitigation and avoidance of the potential impacts to 
CHAPTER 4

Air Quality and Climate

4-55

air quality within the planning area. These changes 

are included in the preferred alternative. 

The data contained within the SAQA are intended to 

augment information in the DSEIS, not replace it.

Project-related emissions include those from CBNG 

construction and operations activities in Montana. 

The scenarios presented within the SAQA were 

analyzed to achieve the following: 

• Assess project-related versus non-projectrelated CBNG emissions under Revised 

Alternative H. 

• Assess emissions associated with compressor 

operations using different NOX emissions 

factors and adjusting well to field to sales 

compressor ratios to more accurately represent 

current practice within the Montana portion of 

the PRB under scenarios 1 and 2. 

• Assess the level at which project-related

CBNG emissions would have to be reduced to 

achieve zero days of impacts to visibility at the 

PSD Class I areas under scenarios 1A and 2A. 

The DSEIS evaluated potential emissions from Coal 

Bed Natural Gas (CBNG) related activities by 

combining project related CBNG development, as 

outlined in the Reasonably Foreseeable Development 

(RFD) scenario, with non-project related CBNG 

development on the Crow and Northern Cheyenne 

reservations, as outlined in the Reasonably 

Foreseeable Future Actions (RFFA) scenario, into 

one emissions source group. The SAQA evaluates 

these two emissions groups separately to allow for 

the determination of potential air quality impacts that 

result directly from project related CBNG activities. 

Also included are potential air quality impacts from 

emission sources in Montana (All Montana Source 

Group), which includes project related CNBG 

emissions, and cumulative emissions (All Source 

Group) which includes all emissions sources both 

project related and non-project related. Information 

on the potential air quality impacts from specific 

source groups is contained within Appendix C of the 

SAQA document. Additionally, emission points 

representing potential emissions from CBNG 

construction, operations, and maintenance activities 

were decentralized within each watershed to better 

represent actual development conditions. The 

adjustments to emission point locations and the 

separation of RFD and RFFA CBNG wells were 

applied to each of the supplemental scenarios 

analyzed which are described below. Emission 

factors used were derived from the air quality 

modeling analyses conducted for the Statewide 

Document (BLM, 2003) conducted by Argonne 

National Laboratories (Argonne 2002). The air 

modeling analysis was conducted to separate project 

RFD emissions from non-project RFFA emissions; 

decentralize the project RFD and non-project RFFA 

emission source points; and utilize a well to field 

compressor to sales compressor ratio of 240 wells 

connected to 10 field compressors connected to 1 

sales compressor (240:10:1) with a NOX emissions 

factor for compressors of 1.5 grams per brake 

horsepower-hour (1.5 g/bhp-hr). This scenario is 

referred to in the SAQA document as Alternative H 

Revised.

Current CBNG development within the Montana 

portion of the Powder River Basin (PRB) is 

conducted using a ratio of 200 wells connected to 5 

field compressors connected to 1 sales compressor. 

The SAQA includes an air modeling analysis 

scenario which uses this ratio of 200:5:1 and a NOX

emissions factor for compressors of 1.5 g/bhp-hr for 

project RFD wells; the well to field compressor to 

sales compressor ratio for non-project RFFA wells 

was not adjusted. This scenario is referred to as 

scenario 1.

The SAQA also evaluates an air modeling analysis 

scenario (scenario 2) using the 200:5:1 well to field 

compressor to sales compressor ratio and the NOX

emissions factor of 1.0 g/bhp-hr for project RFD 

wells; the NOX emissions factor for non-project 

RFFA wells was not adjusted. The 1.0 g/bhp-hr NOx 

emission factor was selected for scenario 2 to reflect 

an emission level permitted by the Montana 

Department of Environmental Quality (MDEQ) for 

certain CBNG compressors within the PRB. 

scenarios 1 and 2 utilize the same number of 

operating CBNG wells but would have varying 

compressor and horsepower requirements and 

subsequent emissions output related to compressor 

operations. The lowering of the NOX emissions factor 

to reflect some MDEQ permitting levels for scenario

2 would further reduce the emissions associated with 

scenario 1.

The SAQA evaluates a mitigation scenario (scenario

1A) which assumes a 50% reduction applied to 

scenario 1 compressor horsepower requirements. 

This scenario reduces compressor operations 

emissions and associated maintenance emissions by 

50% but leaves all other emissions the same as 

previously modeled for scenario 1. The effect of this 

assumption reduces calculated compressor emissions 

by 50% for NOX, SO2, PM10, and PM2.5. 

The SAQA evaluates a second air quality mitigation 

scenario (scenario 2A) which assumes a 50% 

reduction applied to the scenario 2 compressor 

horsepower requirements. This scenario reduces 
CHAPTER 4

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4-56

compressor operations emissions and associated 

maintenance emissions by 50% but leaves all other 

emissions the same as previously modeled for 

scenario 2. The effect of this assumption reduces 

calculated compressor emissions by 50% for NOX, 

SO2, PM10, and PM2.5. 

The SAQA also includes revised emissions data for 

the Tongue River Railroad (TRR) which was 

reconfigured to better simulate a linear emission 

source. The total emissions for the TRR were kept 

constant and are the same as presented in the 

AQTSD; however, the number of emission points 

representing the TRR alignment was increased from 

20 to 96.

Project related emissions include emissions from 

CBNG construction and operations activities in 

Montana. The five scenarios presented were 

analyzed to assess project related versus non-project 

related CBNG emissions under Revised Alternative 

H, assess emissions associated with compressor 

operations utilizing different NOX emissions factors 

and adjusting well to field to sales compressor ratios 

to more accurately represents current practice within 

the Montana portion of the PRB under scenarios 1 

and 2, and assess at what level project related CBNG 

emissions would need to be reduced to achieve zero 

days of impacts to visibility at the Prevention of 

Significant Deterioration (PSD) Class I areas under 

scenarios 1A and 2A.

The SAQA analyses used the CALMET and 

CALPUFF models to assess the potential for impacts 

from project-related and non-project-related

cumulative air emissions of PM10, PM2.5, NOX, and 

SO2 on air quality and air quality related values at 

near-field receptor locations within the PRB and farfield receptor locations within the modeling domain. 

Far-field receptor locations consist of PSD Class I 

and Class II areas. Results of these analyses show 

that project-related CBNG activities would not have 

the potential to exceed NAAQS or MAAQS for NO2, 

PM10, PM2.5, or SO2 under any of the scenarios 

evaluated at either near-field or far-field receptors or 

NO2, PM10, or SO2 PSD increments.

Visibility impacts to Class I and Class II areas were 

evaluated using the Federal Land Managers Air 

Quality Related Values Workgroup (FLAG) Method 

2 and the Regional Haze Rule Method 6. Method 6

Results are presented as consistent with the Best 

Available Retrofit Technique (BART) guideline. 

Using Method 6, visibility impacts were evaluated 

for select Class I and Class II areas within the 

modeling domain. Visibility impacts were evaluated

for the designated Class I Northern Cheyenne 

Reservation because of its proximity to proposed 

development. Using Method 6, visibility impacts to 

the Northern Cheyenne Reservation consisted of 19 

days for scenario 1, zero days for scenario 1A, 7 days 

for scenario 2 and zero days of visibility impacts 

under scenario 2A. As a result, BLM modified the 

Air Quality Screen for Alternative H to more 

proactively track development and assess potential 

impacts relative to CBNG project-related

development to mitigate potential visibility impacts 

before any days of visibility impacts would occur 

from project-related development to nearby Class I 

areas; in particular the Northern Cheyenne 

Reservation. 

Climate Change

Introduction

The assessment of greenhouse gas (GHG) emissions 

and climate is an ongoing scientific endeavor. Oil 

and gas development is likely to contribute to future 

emissions of GHGs to the atmosphere. However, 

while it’s generally accepted that human activities are 

changing the composition of Earth's atmosphere; 

important scientific questions remain about how 

much warming will occur, how fast it will occur, and 

how warming will affect the rest of the climate 

system including temperatures, precipitation patterns 

and storms. Additionally, while oil and gas 

development may contribute emissions of GHGs, the 

amount of any contribution cannot be compared to 

any regulatory standards because there are no 

applicable Federal or State standards at this time. It 

has been noted that “[t]o date, many of the models 

needed to make effective decisions at the local and 

regional levels have not been developed” (DOI, 

2007). According to the USGS (2008) “It is 

currently beyond the scope of existing science to 

identify a specific source of CO2 emissions and 

designate it as the cause of specific climate 

impacts...”. The EPA has noted that “Answering 

these questions will require advances in scientific 

knowledge in a number of areas:

• Improving understanding of natural climatic 

variations, changes in the sun's energy, landuse changes, the warming or cooling effects 

of pollutant aerosols, and the impacts of 

changing humidity and cloud cover. 

• Determining the relative contribution to 

climate change of human activities and 

natural causes. 

• Projecting future greenhouse emissions and 

how the climate system will respond within 

a narrow range. 
CHAPTER 4

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4-57

• Improving understanding of the potential for 

rapid or abrupt climate change. 

Addressing these and other areas of scientific 

uncertainty is a major priority of the U.S. Climate 

Change Science Program (CCSP).” (EPA, 2007; 

http://www.epa.gov/climatechange/science/stateofkn

owledge.html#ref). 

Given these analysis limitations, accounting and 

disclosure of potential GHG emissions is the 

preferred option at this time. A comparison between 

project emissions and total State, U.S. and global 

emissions is provided on Table 4-CC-3.

This analysis focuses on GHG emissions from CBNG 

development. The development of CBNG in 

Montana is not anticipated to noticeably affect sinks 

of GHGs, and the feasibility of CBNG development 

is not anticipated to be affected by global climatic 

change. 

Five scenarios were evaluated for GHG emissions 

from CBNG development in Montana. These are No 

Action (Alternative A), high RFD with no screens 

(Alternatives B, C, D and E), high RFD with 

restrictive screens (Alternative F), low RFD with 

restrictive screens (Alternative G), and high RFD 

with less restrictive screens (Alternative H). 

Sources of CO2 from the project include emissions 

from construction activities, operations, and 

maintenance. The emissions for each type of source 

were discretely determined for Alternatives B, C, D 

and E which were based on the high RFD with no 

screens (see table 4-CC-1). For other alternatives the 

emissions were proportioned based upon the ratio of 

gas anticipated to be produced in each alternative 

relative to the high RFD with no screens (see Table 

4-CC-2). 

The EPA has noted that “[t]he U.S. natural gas 

system encompasses hundreds of thousands of wells, 

hundreds of processing facilities, and over a million 

miles of transmission and distribution pipeline. All 

industry sectors, including gas production, 

processing, transmission, and distribution emit 

methane to the atmosphere to varying degrees. 

Methane emissions are generally process-related, 

with normal operations, routine maintenance, and 

system upsets being the primary contributors” (EPA, 

2007b). The amount of methane (CH4) that is emitted 

relative to the amount of gas produced was calculated 

by using Energy Information Administration (EIA) 

estimates of US total methane emissions from natural

gas systems (EIA, 2007) from 1995 to 2006, plotted 

against EIA data for the gross withdrawal of natural 

gas (EIA, 2008). EIA methane emission data (EIA, 

2007) also allows for the estimation of the likely 

sources of methane emissions, with emissions from 

production and processing accounting for 37.9% of 

methane emissions from natural gas systems. This 

allows for the calculation of an emission factor of 

2.36 million metric tones (MMT) carbon dioxide 

equivalent (CO2e) of methane per trillion cubic feet 

(TCF) of gas produced. 

The adoption of the EPA’s Gas STAR BMPs is not a 

part of any of the alternatives, and it is a voluntary 

program; however if these practices were employed it 

would reduce the volume of methane emitted per 

TCF of gas and emissions would be less than 

reported from this analysis. By following these 

practices the EPA has reported reductions of 85.9 

BCF of emissions for 2006 (the latest year figures 

were available for). EPA estimates that this is the 

equivalent of removing approximately 7.5 million 

cars from the road for the year. 

Calculated CH4 emission values are combined with 

the CO2 emissions values to give a total GHG 

emission value for each alternative in terms of CO2e. 

These resulting values are divided by 40 to give an 

average annual emission rate. This annual emission 

rate is then compared to existing (2004 & 2005) and 

projected statewide, nationwide and global emissions 

values (see Table 4-CC-3). 

Impacts from Management Specific to 

Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

There would be no additional contribution to 

atmospheric CO2e levels from the development of 

CBNG in Montana under this alternative. See Tables 

4-CC-2 and 4-CC-3 for CO2e emissions that are 

projected result with no additional CBNG 

development in Montana.

Alternatives B, C, D, & E

Construction activities, operations, and maintenance 

would result in CO2 emissions. CO2 emissions over 

the 40 year life of the project would be approximately 

45.9 MMT (see Table 4-CC-1). Emissions of 

methane are anticipated to equal approximately 11.8 

MMT in CO2 equivalents (CO2e) over the life of the 

project. These emissions combine to contribute 57.7 

MMT of CO2e over the 40 year life of the project 

(see Table 4-CC-2); or an average of 1.44 MMT of 

CO2e per year. According to the EPA’s online

calculator (EPA, 2008c; 

http://www.epa.gov/cleanenergy/energy-
CHAPTER 4

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4-58

resources/calculator.html

Cumulative Impacts:

) this average annual rate 

would be approximately equivalent to the annual 

greenhouse gas emissions from 264,000 passenger 

vehicles, or the annual CO2 emissions of 0.3 coal 

fired power plants.

The CCS conducted an inventory of GHG emissions 

in the State of Montana for 2005 (CCS, 2007). These 

values indicate that CBNG development under these 

alternatives would add approximately 3.9% to the 

State’s emissions (see Table 4-CC-3). 

Data from the EIA (2007) and the EPA (2006) can be 

used to estimate total 2005 U.S. GHG emissions and 

total 2004 global GHG emissions. In these contexts 

the annual emissions of GHGs from CBNG 

development in Montana under these alternatives 

would cause a 0.020% and a 0.0039% increase 

respectively (see Table 4-CC-3).

The cumulative impact of the GHG emissions from 

the SEIS decisions (CBNG development) together 

with other activities with GHG emissions that have 

occurred, are occurring or are reasonably foreseeable 

are set forth herein. Assuming there are other GHG 

emitting activities that have, are, or will occur, the 

impacts of those activities, together with this 

Amendment’s activities could result in certain 

climatic changes. 

Montana emissions projections for 2010 and 2020 are 

also available from the CCS GHG Inventory (2007). 

These projections “are based on a compilation of 

various existing projections of electricity generation, 

fuel use, and other GHG emitting activities” (CCS, 

2007) and as such it incorporates all past present and 

reasonably foreseeable GHG emitting activities in the 

State. The reference case scenario “[a]ssumes very 

limited CBM activity”. Therefore, this scenario is 

comparable to that assumed for Alternative A 

(Existing Management), and is used as the baseline 

for this analysis. Based upon these values CBNG 

development under these alternatives would add 

approximately 3.7% to the State’s emissions in 2010 

and 3.5% to the State’s emissions in 2020 (see Table 

4-CC-3). 

Using data from the EIA (2007) and the EPA (2006) 

the U.S. and global GHG emissions can be projected 

for 2010 and 2020. These projections incorporate all 

past present and reasonably foreseeable GHG 

emitting activities. Relative to the U.S. values for 

2010 and 2020 the annual emissions of GHGs from

CBNG development in Montana under these 

alternatives would cause a 0.019% and a 0.017%

increase respectively. Relative to the global data for 

2010 and 2020 the annual emissions of GHGs from 

CBNG development in Montana under these 

alternatives would cause a 0.0034% and a 0.0029% 

increase respectively. 

The EPA has evaluated the likely cumulative impacts 

from increased atmospheric CO2 levels for the 

mountain west (EPA Region 8; EPA 2008a; 

http://www.epa.gov/region8/climatechange/ClimateC

hange101FINAL.pdf

At a broader level the EPA has evaluated a variety of 

potential national and global impacts from climate 

change (EPA 2007b; 

). This evaluation is included by 

reference here. This analysis indicates that “In the 

coming decades, scientists project that climate 

change will lead to significant changes in the 

Mountain West and Great Plains”. The mid-range of 

the IPCC is for a change of 5.4oF. This is enough to 

make Missoula as warm as Denver is now. 

www.epa.gov/climatechange/effects/index.html). 

This evaluation is included by reference here. These 

impacts include an increase in average temperature, 

shrinking of glaciers, thawing of permafrost, later 

freezing and earlier break-up of ice on rivers and 

lakes, lengthening of growing seasons, shifts in plant 

and animal ranges and earlier flowering of trees. 

Human health, agriculture, natural ecosystems, 

coastal areas, and heating and cooling requirements 

are examples of systems that are sensitive to climate 

change.

Additional discussions of the various types of 

impacts that can be expected from climate change are 

available at the EPA’s Climate Change website 

(www.epa.gov/climatechange) (EPA, 2008c).

According to the Intergovernmental Panel on Climate 

Change (IPCC, 2007) global climate change may 

ultimately contribute to a rise in sea level, destruction

of estuaries and coastal wetlands, and changes in 

regional temperature and rainfall patterns, with major 

implications to agricultural and coastal communities. 

The IPCC has suggested that the average global 

surface temperature could rise 1 to 4.5 degrees 

Fahrenheit (°F) in the next 50 years, with significant 

regional variation. The National Academy of 

Sciences (2008) has confirmed these estimates, but 

also indicated that there are uncertainties regarding 

how climate change may affect different regions. 

Computer models indicate that such increases in 

temperature will not be equally distributed globally, 

but are likely to be accentuated at higher latitudes, 

such as in the Arctic, where the temperature increase 

may be more than double the global average (BLM 

2007). Also, warming during the winter months is 

expected to be greater than during the summer, and 

increases in daily minimum temperatures is more 
CHAPTER 4

Air Quality and Climate

4-59

TABLE 4-CC-1: 

PROJECTED CO2 EMISSIONS FROM CBNG 

DEVELOPMENT BASED ON THE RFD FOR 

ALTERNATIVES B, C, D, AND E

CO2

Emission Source (MMT) % of total

Construction Emissions

Heavy Equipment 0.64 1.4%

Commuting Vehicles 0.01 0.02%

Total Construction 0.65 1.42%

Operations Emissions

Compressor Stations

Field Compressors 9.87 21.5%

Sales Compressors 34.80 75.9%

Dehydrators 0.49 1.1%

Commuting Vehicles 0.0001 0.0003%

Wells

Workovers - On-site 0.04 0.08%

Workovers - On-road 0.001 0.003%

Well and Pipeline 

Inspections 0.001 0.003%

Total Operations 45.20 98.55%

Maintenance Emissions

Road Maintenance

Heavy Equipment 0.01 0.03%

Commuting Vehicles 0.0001 0.0002%

Compressor Station Maintenance

Commuting 

Vehicles 0.0002 0.000%

Total Maintenance 0.014 0.03%

TOTAL CO2 EMISSIONS 45.9

(Well:Field:Sales = 200:5:1)

likely than increases in daily maximum temperatures. 

Vulnerabilities to climate change depend 

considerably on specific geographic and social 

contexts.

Alternative F—Phased Development 

Multiple Screens (High Range)

Construction activities, operations, and maintenance 

would result in CO2 emissions. CO2 emissions over 

the 40 year life of the project would be approximately 

25.7 MMT. Emissions of methane are anticipated to 

equal approximately 6.6 MMT in CO2e over the life 

of the project. These emissions combine to 

contribute 32.3 MMT of CO2e over the 40 year life of 

the project (see Table 4-CC-2); or an average of 0.81 

MMT of CO2e per year. According to the EPA’s 

online calculator (EPA, 2008b; 

http://www.epa.gov/cleanenergy/energyresources/calculator.html) this average annual rate

TABLE 4-CC-2: 

PROJECTED CBNG CO2 AND CH4 EMISSIONS BY 

ALTERNATIVE OVER THE LIFE OF THE 

PROJECT

Alternative

Estimated

CO2

Emissions

(MMT 

CO2e)

Estimated

CH4

Emissions

(MMT 

CO2e)

Total 

Estimated

Emissions

(MMT 

CO2e)

Alt A 0.0 0.0 0.0

Alts B,C,D & E 45.9 11.8 57.7

Alt F 25.7 6.6 32.3

Alt G 9.2 2.4 11.5

Alt H 31.2 8.0 39.2

MMT = Millions of Metric Tons

CO2e = Carbon Dioxide Equivalent

would be approximately equivalent to the annual 

greenhouse gas emissions from 148,000 passenger 

vehicles, or the annual CO2 emissions of 0.2 coal 

fired power plants.

The Center for Climate Strategies conducted an 

inventory of GHG emissions in the State of Montana 

for 2005 (CCS, 2007). These values indicate that 

CBNG development would add approximately 2.2% 

to the State’s emissions under this alternative (see 

Table 4-CC-3). 

Data from the EIA (2007) and the EPA (2006) can be 

used to estimate total 2005 U.S. GHG emissions and 

total 2004 global GHG emissions. In these contexts 

the annual emissions of GHGs from CBNG 

development in Montana under this alternative would 

cause a 0.011% and a 0.0022% increase respectively 

(see Table 4-CC-3). 

Cumulative Impacts:

Based upon the CCS GHG Inventory (2007) CBNG 

development under this alternative would add 

approximately 2.1% to the State’s emissions in 2010 

and 1.9% to the State’s emissions in 2020 (see Table 

4-CC-3). 

Using data from the EIA (2007) and the EPA (2006) 

the U.S. and global GHG emissions can be projected 

for 2010 and 2020. Relative to the U.S. values for 

2010 and 2020 the annual emissions of GHGs from 

CBNG development in Montana under this 

alternative would cause a 0.011% and a 0.010% 

increase respectively. Relative to the global data for 

2010 and 2020 the annual emissions of GHGs from 

CBNG development in Montana under these 

alternatives would cause a 0.0019% and a 0.0016% 

increase respectively (see Table 4-CC-3).
CHAPTER 4

Air Quality and Climate

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TABLE 4-CC-3:

COMPARISON OF MONTANA, U.S. AND GLOBAL CO2E EMISSIONS & PROJECTIONS 

TO CO2E EMISSIONS PROJECTED FOR CBNG DEVELOPMENT IN MONTANA

MMT of Emissions per Year

Existing*

(2004/2005)

Projected

2010 2020

Alternative A 

Montana1 MMT CO2e 36.8 38.5 41.7

U.S.2 MMT CO2e 7,181 7,405 8,275

Global2 MMT CO2e 36,510 41,851 49,750

Alternatives B,C,D & E

Montana

MMT CO2e 38.2 39.9 43.1

% diff+ 3.9% 3.7% 3.5%

U.S.

MMT CO2e 7,182 7,406 8,276

% diff+ 0.020% 0.019% 0.017%

Global

MMT CO2e 36,511 41,852 49,751

% diff+ 0.0039% 0.0034% 0.0029%

Alternative F 

Montana

MMT CO2e 37.6 39.3 42.5

% diff+ 2.2% 2.1% 1.9%

U.S.

MMT CO2e 7,182 7,406 8,275

% diff+ 0.011% 0.011% 0.010%

Global

MMT CO2e 36,511 41,852 49,751

% diff+ 0.0022% 0.0019% 0.0016%

Alternative G 

Montana

MMT CO2e 37.1 38.8 42.0

% diff+ 0.8% 0.7% 0.7%

U.S.

MMT CO2e 7,181 7,405 8,275

% diff+ 0.004% 0.004% 0.003%

Global

MMT CO2e 36,510 41,851 49,750

% diff+ 0.0008% 0.0007% 0.0006%

Alternative H 

Montana

MMT CO2e 37.8 39.5 42.7

% diff+ 2.7% 2.5% 2.4%

U.S.

MMT CO2e 7,182 7,406 8,276

% diff+ 0.014% 0.013% 0.012%

Global

MMT CO2e 36,511 41,852 49,751

% diff+ 0.0027% 0.0023% 0.0020%

* Values for Montana and the U.S. are for 2005, global values are for 2004.

1 = CSC, 2007 2 = EIA, 2007 and EPA, 2006

MMT = Millions of Metric Tons

CO2e = Carbon Dioxide Equivalent + % difference from the No Action

The likely cumulative climatic impacts from 

increased atmospheric CO2e levels would not be 

measurably different from those described for 

alternatives B, C, D and E. 

Alternative G—Phased Development 

Multiple Screens (Low Range)

Construction activities, operations, and maintenance 

would result in CO2 emissions. CO2 emissions over 

the 40 year life of the project would be approximately 

9.2 MMT. Emissions of methane are anticipated to 

equal approximately 2.4 MMT in CO2e over the life 

of the project. These emissions combine to 

contribute 11.5 MMT of CO2e over the 40 year life of 

the project (see Table 4-CC-2); or an average of 0.29 

MMT of CO2e per year. According to the EPA’s 

online calculator (EPA, 2008b; 

http://www.epa.gov/cleanenergy/energyresources/calculator.html) this average annual rate 

would be approximately equivalent to the annual 

greenhouse gas emissions from 53,000 passenger 

vehicles, or the annual CO2 emissions of 0.1 coal 

fired power plants.
CHAPTER 4

Air Quality and Climate

4-61

The Center for Climate Strategies has conducted an 

inventory of GHG emissions in the State of Montana 

for 2005 (CCS, 2007). These values indicate that 

CBNG development would add approximately 0.8% 

to the State’s emissions under this alternative (see 

Table 4-CC-3). 

Data from the EIA (2007) and the EPA (2006) can be 

used to estimate total 2005 U.S. GHG emissions and 

total 2004 global GHG emissions. In these contexts 

the annual emissions of GHGs from CBNG 

development in Montana under this alternative would

cause a 0.004% and a 0.0008% increase respectively 

(see Table 4-CC-3).

Cumulative Impacts:

Based upon the CCS GHG Inventory (2007) CBNG 

development under this alternative would add 

approximately 0.7% to the State’s emissions in 2010 

and 0.7% to the State’s emissions in 2020 (see Table 

4-CC-3). 

Using data from the EIA (2007) and the EPA (2006) 

the U.S. and global GHG emissions can be projected 

for 2010 and 2020. Relative to the U.S. values for 

2010 and 2020 the annual emissions of GHGs from 

CBNG development in Montana under this 

alternative would cause a 0.004% and a 0.003% 

increase respectively. Relative to the global data for 

2010 and 2020 the annual emissions of GHGs from 

CBNG development in Montana under these 

alternatives would cause a 0.0007% and a 0.0006% 

increase respectively.

The likely cumulative climatic impacts from 

increased atmospheric CO2e levels would not be 

measurably different from those described for 

alternatives B, C, D and E. 

Alternative H—Preferred Alternative - 

Multiple Screens

Construction activities, operations, and maintenance 

would result in CO2 emissions. CO2 emissions over 

the 40 year life of the project would be approximately 

31.2 MMT. Emissions of methane are anticipated to 

equal approximately 8.0 MMT in CO2e over the life 

of the project. These emissions combine to 

contribute 39.2 MMT of CO2e over the 40 year life of 

the project (see Table 4-CC-2); or an average of 0.98 

MMT of CO2e per year. According to the EPA’s 

online calculator (EPA, 2008b; 

http://www.epa.gov/cleanenergy/energyresources/calculator.html) this average annual rate 

would be approximately equivalent to the annual 

greenhouse gas emissions from 179,000 passenger 

vehicles, or the annual CO2 emissions of 0.2 coal 

fired power plants.

The Center for Climate Strategies conducted an 

inventory of GHG emissions in the State of Montana 

for 2005 (CCS, 2007). These values indicate that 

CBNG development would add approximately 2.7% 

to the State’s emissions under this alternative (see

Table 4-CC-3). 

Data from the EIA (2007) and the EPA (2006) can be 

used to estimate total 2005 U.S. GHG emissions and 

total 2004 global GHG emissions. In these contexts 

the annual emissions of GHGs from CBNG 

development in Montana under this alternative would 

cause a 0.014% and a 0.0027% increase respectively 

(see Table 4-CC-3).

Cumulative Impacts:

Based upon the CCS GHG Inventory (2007) CBNG 

development under this alternative would add 

approximately 2.5% to the State’s emissions in 2010 

and 2.4% to the State’s emissions in 2020 (see Table 

4-CC-3). 

Using data from the EIA (2007) and the EPA (2006) 

the U.S. and global GHG emissions can be projected 

for 2010 and 2020. Relative to the U.S. values for 

2010 and 2020 the annual emissions of GHGs from 

CBNG development in Montana under this 

alternative would cause a 0.013% and a 0.012% 

increase respectively. Relative to the global data for 

2010 and 2020 the annual emissions of GHGs from 

CBNG development in Montana under these 

alternatives would cause a 0.0023% and a 0.0020% 

increase respectively.

The likely cumulative climatic impacts from 

increased atmospheric CO2e levels would not be 

measurably different from those described for 

alternatives B, C, D and E.
CHAPTER 4

Cultural Resources

4-62

Cultural Resources

Cultural Resources

Approximately 73,600 cultural resource sites exist above known 

coal resources within the CBNG emphasis area

Alternative A

No Action (Existing CBNG Management)

• An estimated 17 cultural resource sites could be identified 

during foreseen CBNG activities. Of these only one or 

two would likely be eligible or need additional work to 

evaluate eligibility for the NRHP. 

• Cumulative Impacts:

− An estimated 4,285 cultural sites could be identified 

resulting in 430 to 612 sites that could be eligible for 

the NRHP.

Alternatives B, C and D 

• The number of cultural resource sites identified would be 

practically the same for Alternatives B, C and D based on 

the level of development, associated area of disturbance 

and minor differences between the alternative realty 

management actions. An estimated 630 cultural resource 

sites could be identified.

• Cumulative Impacts:

− An estimated 5,135 cultural sites could be identified. 

Of these between 514 and 734 sites would likely be 

eligible or need additional work to evaluate 

eligibility for the NRHP. 

− Potential for impacts to TCPs would increase with 

the development of CBNG. 

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• An estimated 893 to 1,080 cultural resource sites could be 

identified.

• Cumulative Impacts:

− An estimated 5,398 to 5,585 cultural sites could be 

identified. Of these between 540 and 798 sites would 

likely be eligible or need additional work to evaluate 

eligibility for the NRHP.

− Potential for impacts to TCPs would increase with 

the development of CBNG.

Alternative F

Phased Development Multiple Screens (High Range)

• The number of cultural resource sites identified would be 

similar to Alternative E. 

• An estimated 893 to 1,080 cultural resource sites could be 

identified. 

• Should no drilling occur within crucial sage-grouse 

habitat, the number of cultural resources sites that could 

be identified would be reduced by 12.8 percent. 

• Cumulative Impacts:

− An estimated 5,398 to 5,585 cultural sites could be 

identified. Of these between 540 and 798 sites would 

likely be eligible or need additional work to evaluate 

eligibility for the NRHP.

− The potential for impacts to TCPs would increase 

with the development of CBNG.

− Should no drilling occur within crucial sage-grouse 

habitat, the cumulative number of cultural resources 

sites that could be identified would be reduced from 

5,447 to 5,284.

Alternative G 

Phased Development Multiple Screens (Low Range)

• Impacts would be similar to those for Alternative F, 

except that expected impacts to cultural resource sites 

would be reduced by approximately 65 percent due to 

fewer federal applications for permit to drill (APDs) being

issued.

• An estimated 312 to 378 cultural resource sites could be 

identified based on the reduced number of federal APDs 

being issued. 

• Cumulative Impacts:

• An estimated 4,817 to 4,883 cultural sites could be 

identified based on the reduced number of federal 

APDs being issued. Of these between 482 and 698 

sites would likely be eligible or need additional 

work to evaluate eligibility for the National register 

of Historic Places (NRHP). 

• Potential for impacts to TCPs would be similar to 

Alternative F, but would be reduced by 

approximately 65 percent based on the reduced 

number of federal APDs being issued. 

Alternative H 

Preferred Alternative - Multiple Screens

• The number of cultural resource sites identified would be 

similar to those for Alternatives E and F.

• Should no drilling occur within crucial sage-grouse 

habitat, the number of cultural resources sites that could 

be identified would be reduced by 12.8 percent

• An estimated 893 to 1080 cultural resource sites could be 

identified.

• Cumulative Impacts:

• An estimated 5,398 to 5,585 cultural sites could be 

identified. Of these between 540 and 798 sites would 

likely be eligible or need additional work to evaluate 

eligibility for the NRHP.

• Potential for impacts to TCPs would increase with 

the development of CBNG.

Assumptions

Cultural resources would be treated similarly and 

equally in terms of type, composition and

significance; their distributions and densities are 

detailed in Chapter 3. Cultural resources are treated 

in this manner only for purposes of evaluation in this 

report, since the particular cultural resources to be 

affected are not necessarily known at this time. It 

must be understood that not all cultural resources are 

equal in terms of importance, National Register 

eligibility, density and location. Federally recognized 

tribes will need to be consulted, consistent with the 

requirements of the National Historic Preservation

Act (NHPA) and regulations found at 36 Code of 

Federal Regulations (CFR) Part 800. Most of the 

mitigation for Native American cultural resources 
CHAPTER 4

Cultural Resources

4-63

will entail avoidance, particularly any site associated 

with burials of human remains. Cultural resource 

attributes will have to be taken into consideration 

when impacts are considered for each individual 

CBNG development. Operators will need to develop 

an approach for mitigating cultural resources based 

on the plan for CBNG development that they submit. 

The Cultural Resource section of that plan will need 

to include the following guidelines in BLM's 8100 

Manual Series, the Secretary of the Interior’s 

Standards and Guidelines For Archaeology and 

Historic Preservation (FR 48 (190)44716-44742, 

1983) and the Advisory Council on Historic 

Preservation’s document the “Treatment of 

Archaeological Properties” (ACHP 1980) 

Surface disturbance assumptions are detailed in the 

Analysis Assumptions and Guidelines section of this 

chapter. There would be one site for every 100 acres 

surveyed for cultural resources. This assumption was 

made by averaging the number of sites vs. acres 

surveyed in the Planning Area from existing surveys. 

This estimate is based on surveys that covered 

19 percent of the estimated CBNG development area. 

The actual number of cultural resources in a 

particular CBNG development field could vary 

dramatically depending on the exact location of the 

field.

Impacts from Management Common 

To All Alternatives

Cultural resources would be impacted by surface and 

subsurface disturbing activities. Activities that 

involve the use of heavy equipment (road 

construction, well drilling, pad construction, pipeline 

and utility placement, etc.) that result in changes to 

the natural landscape could cause the most 

disturbance and could have the greatest effect on 

cultural resources. Other activities, such as increased 

travel and vandalism resulting from access

improvements and increased erosion resulting from 

surface disturbances, would also impact cultural 

resources. These activities can also produce indirect 

impacts to cultural resources from fires; and to rock 

art sites from gas emissions, abrasive dust and

vibrations from drilling equipment. Noise, activity, 

traffic and smells can affect the quality and continued 

use of Traditional Cultural Properties (TCPs). 

Traditional Cultural Properties important to the 

Northern Cheyenne and Crow and their perceptions 

of mitigation are presented in The Northern 

Cheyenne Tribe and its Reservation: 2002 (The 

Northern Cheyenne Tribe 2002), Crow Reservation

(Crow Tribe of Indians 2002) and An Ethnographic 

Overview of Southeast Montana (Peterson and 

Deaver 2002).

Impacts would occur at an estimated 318 cultural 

resource sites. Of these sites, 32 to 46 are projected to 

be eligible for the National Register of Historic 

Places. The estimated number of sites includes 

176 cultural resource sites from disturbance by 

conventional oil and gas development and 142 sites 

as a result of impacts caused by cumulative projects 

foreseen including surface coal mining activities. 

Additional cultural resources could be found as a 

result of cultural resource inventories conducted 

before beginning surface disturbing activities. 

Locating additional cultural resources would result in 

a better understanding of the nature and distribution 

of those resources. 

The TRR tabulated all cultural resources within a 

100-foot ROW of the proposed corridor and 

extending 1,500 feet on either side of the alignment. 

The Surface Transportation Board’s environmental 

analysis section for its SEIS indicated that with 

mitigation neither the construction nor the operation 

of the TRR would result in significant impacts to 

cultural resources.

Identified traditional cultural properties within the 

3,000-foot-wide corridor consist of two known sites. 

One site (24BH1617) was identified as a medicine 

wheel and the other site is an important paint/mineral 

source currently used by the Northern Cheyenne 

Tribe to obtain red ochre (Deaver and Tallbull 1991) 

Both of these sites could be affected by visual or 

audible impacts caused during construction; however, 

mitigation measures, as agreed to with the tribes, 

would be implemented.

Based on the information presented in the 

environmental analysis section of the FSEIS, it 

appears that battlefields and TCPs would most likely 

be indirectly affected by TRR operation and 

maintenance. 

Impacts from Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG

Management)

Alternative A has the least impact to cultural 

resources of all alternatives since this alternative has 

the least amount of surface and subsurface 

disturbance. Approximately 17 cultural resource sites 

would be identified by all projected CBNG activities 

in state and BLM planning areas. An estimated four 

sites would be impacted from exploration activities in 
CHAPTER 4

Cultural Resources

4-64

state planning areas; six sites would be impacted 

from production activities at CX Ranch; and seven 

would be impacted from exploration activities in 

BLM planning areas. One or two of these identified 

sites could be found eligible for the National Register 

of Historic Places. There would be no production 

activities in BLM planning areas under this 

alternative and therefore no impacts from production.

Crow Reservation

Impacts to cultural resources on the Crow 

Reservation are not expected because no exploration 

wells are planned for installation on the Reservation 

at this time. However if exploration wells were to be 

drilled on the Reservation the likelihood of site 

impacts would occur at a similar frequency as 

described for Cultural Resources in general though 

there could be an increase in cultural resource sites 

identified because of the increased number of 

possible TCPs.

Northern Cheyenne Reservation

Impacts to cultural resources on the Northern 

Cheyenne Reservation also are not expected at this 

time because the Northern Cheyenne have not 

indicated that exploration wells would be drilled. As 

with the Crow Reservation, it is anticipated that, 

should the Northern Cheyenne Tribe explore its

reservation for CBNG resources, cultural resources

would be encountered with the same regularity as 

described for cultural resources in general. It is 

conceivable that the density of cultural sites would be 

increased on the reservation because of the increased 

possibility of TCPs. It is assumed that the tribe would 

be involved in all surveys and site inspections on the 

reservation. Therefore, the incidents of cultural 

resource impacts could be minimized and possibly 

avoided altogether.

Conclusion

Over the next 20 years, disturbances from CBNG

development, conventional oil and gas development

and other cumulative effect analysis project activities 

could identify 4,285 cultural resource sites. Impacts 

from surface disturbance would be minimized by 

using existing disturbances where possible and by 

allowing aboveground utility lines. The impacts from 

erosion as a result of surface discharge of produced 

water at CX Ranch would be negligible because of 

the conveyance systems used to transport the 

relatively small amount of discharged water. The 

mitigation measures would be the same as those 

discussed in Chapter 2. However, given the number 

of acres likely to be disturbed by all anticipated 

CBNG development, it is unlikely that it would be 

necessary to mitigate sites or cultural properties 

through data recovery. In almost all situations, direct 

impacts to cultural properties would be avoided by 

relocating well sites or pipelines. Monitoring may 

indicate sites adjacent to the development fields are 

being indirectly affected by vandalism and other 

types of indirect impacts in which case data recovery 

would be the preferred mitigation. Consultation with 

tribes may indicate the presence of TCPs that would 

have to be avoided or which would require alteration 

of the well field plan in order to mitigate impacts to 

TCPs.

These are the best estimates of cultural resources that 

can be derived at this level of study. It is understood 

that sites occur in clusters based on a host of various 

criteria (location to water, slope, view, predominate 

wind, etc) and that some sites are more important 

than others.

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Under this alternative, an estimated 629 cultural 

resource sites would be identified by all projected 

CBNG activities in state and BLM planning areas. 

An estimated 16 sites would be impacted by 

exploration activities in state planning areas, 335 

sites from production activities in state planning 

areas, 10 sites from exploration activities in BLM 

planning areas and 269 sites from production 

activities on BLM planning areas.

Crow Reservation

Impacts to cultural resources on the Crow 

Reservation would be minimal because no 

development is anticipated on the reservation at this 

time. Disturbance totals include TCPs that would be 

identified off reservation and impacted from the 

above mentioned activities.

Northern Cheyenne Reservation

There would be no impacts to cultural resources on

the Northern Cheyenne Reservation based on 

commercial CBNG development within the region. 

Disturbance totals include TCPs that would be 

identified off reservation and impacted from the 

above mentioned activities.

Conclusion

Over the next 20 years, disturbances from CBNG

development in state, BLM, Native American and
CHAPTER 4

Cultural Resources

4-65

USFS planning areas; conventional oil and gas 

development; and surface coal mining activities 

would identify approximately 5,135 cultural resource 

sites. These totals include traditional cultural 

properties that would be identified and impacted from 

the abovementioned activities. The requirement of 

transportation corridors, one-way in-and-out roads

and the prevention of surface discharge of produced 

water would help to minimize the number of cultural 

resource sites impacted. The mitigation measures

would be the same as those discussed in Chapter 2.

Alternative C—Emphasize CBNG

Development

Under this alternative, impacts to cultural resources 

would be similar to Alternative B with the following 

exceptions: transportation corridors are not required, 

thereby increasing the number of disturbed acres and 

the likelihood of identifying and, hence, disturbing,

more sites; discharge of produced water directly to 

the ground surface would increase erosion and site 

disturbance; power lines may be aboveground or 

buried, which would decrease the number of 

disturbed acres. The estimated number of cultural 

sites identified under Alternative C would total 629.

Crow Reservation

There would be no impacts to cultural resources on

the Crow Reservation from commercial CBNG

development in the region. 

Northern Cheyenne Reservation

Impacts to cultural resources on the Northern 

Cheyenne Reservation would be minimal based on 

the off-reservation development and avoidance 

practices employed. 

Conclusion

Cumulative impacts would be similar to 

Alternative B with some exceptions. The surface 

disturbance from roads and utilities would be greater 

because one-way in-and-out roads and transportation 

corridors would not be required. Cultural resource 

inventories would need to be conducted along the 

surface watercourses. Surface discharge of produced 

water would result in increased erosion. The 

discharge of produced water to the surface would 

increase erosion and cause increased surface 

disturbance. The increased surface disturbance would 

be in the area near the production area and in the 

downstream segments of perennial streams and 

valleys leading to the major surface waters. Further 

discussion of erosion and the disturbances to soils 

can be found in the Soils section of this chapter. 

Mitigation measures would be similar to 

Alternative B with some exceptions. Mitigation 

measures would include the use of piping instead of 

discharging waters into drainage ditches in order to 

minimize erosion.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Under this alternative, impacts to cultural resources 

would be similar to Alternative B.

Crow Reservation

There would be no impacts to cultural resources on 

the Crow Reservation from commercial CBNG

development within the region. 

Northern Cheyenne Reservation

There would be no impacts to Northern Cheyenne 

cultural resources on the reservation from offreservation CBNG development. Off-reservation 

TCPs may be impacted in some locals but avoidance 

and early identification should eliminate any 

important sites from being disturbed.

Conclusion

Cumulative impacts would be similar to 

Alternative B. Mitigation measures would be the 

same as for Alternative B.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts while 

Maintaining Existing Land Uses

Under this alternative, the impact to cultural 

resources would be similar to Alternative B with the 

following exceptions: the removal of an inactive 

buffer zone around active coal mines and reservations 

would increase the potential acreage for CBNG

development and hence potentially increase the 

number of cultural resources encountered; there 

might be a decrease in the number of well pads built 

since operators would be able to use vertical wells for 

deep coal seams; transportation and utility corridors 

are not required, thereby increasing the number of 

disturbed acres and hence encountered cultural 

resources; power lines may be aboveground or 

buried, which should decrease the number of 

disturbed acres in most areas. 
CHAPTER 4

Cultural Resources

4-66

The operator’s project plan would help develop a 

survey identification strategy and increase the 

likelihood of cultural resource identification and 

implementation of mitigation measures. The 

estimated number of cultural resources identified 

under Alternative E would be 893 to 1,080. 

Additional cultural resources could be found as a 

result of cultural resource inventories conducted 

before beginning surface disturbing activities. 

Locating cultural resources would result in a better 

understanding of the nature and distribution of those 

resources. 

Crow Reservation

No cultural resources would be impacted on the 

Crow Reservation from commercial CBNG

development off-reservation lands. With regards to 

off-reservation TCPs, the BLM has developed 

specific mitigation measures for protecting sites of 

religious and cultural concern to Native Americans. 

These measures have been developed in consultation 

with the tribes and their representatives.

Northern Cheyenne Reservation

No cultural resources would be impacted on the 

Northern Cheyenne Reservation from commercial 

CBNG development off-reservation lands. With 

regards to off-reservation TCPs, the BLM has 

developed specific mitigation measures for protecting 

sites of religious and cultural concern to Native 

Americans. These measures have been developed in 

consultation with the tribes and their representatives. 

These measures include provisions for information 

sharing and for the prevention of impacts to Northern 

Cheyenne homestead sites, traditional plant gathering 

sites, important hunting and fishing locations, 

culturally significant springs, grave sites and human 

remains. 

With these specific measures in place to mitigate 

impacts to Northern Cheyenne culturally important 

sites and with the BLM committed to providing 

technical assistance to the tribe in inventorying, 

recording and evaluating cultural sites, it is plausible 

that impacts will be reduced.

Conclusion

Over the next 20 years, disturbances from CBNG 

development, conventional oil and gas development

and other RFFA could identify 5,398 to 5,585

cultural resource sites. With the implementation of 

specific Northern Cheyenne and general Native 

American mitigation measures impacts to offreservation TCP sites will be reduced and data 

collection efforts enhanced.

Alternative F—Phased Development 

Multiple Screens (High Range)

Under this alternative an estimated 893 to 1,080

cultural resource sites could be identified during field 

surveys conducted before surface disturbing activities 

occur for proposed CBNG exploration and 

production sites in the Planning Area. Locating 

cultural resource sites would result in the 

accumulation of additional artifacts and information. 

Impacts to cultural resources and sites identified 

before surface disturbing activities occur would be 

similar to those described in Alternatives B, C, D and 

E. Known cultural resources and sites would be 

protected by implementing mitigation measures such 

as locating CBNG activities to avoid cultural 

resources and sites and BMPs. 

Given that some level of development is likely to 

occur in the crucial sage-grouse habitat areas, the 

total acreage of surveyed land will remain the same. 

However, less intense development over 93,529 acres 

would reduce the potential for direct impacts to 

cultural resources within these areas.

Crow Reservation

CBNG activities that would be located off of the 

Crow Reservation would not directly impact cultural 

resources or sites located on the reservation. Cultural 

resources and sites located off of the reservation 

related to the Crow Tribe would be protected because 

activities would be relocated to avoid cultural 

resources and sites. Consultation with the tribe would 

update knowledge about cultural resources and sites 

and improve the likelihood to avoid known cultural 

resources and sites. Information about these resources 

and sites is held confidential by the tribe and BLM 

which minimizes opportunities for the public to 

vandalize or steal cultural resources. With regards to 

off-reservation TCPs, the BLM has developed 

specific mitigation measures for protecting sites of 

religious and cultural concern to Native Americans. 

These measures have been developed in consultation 

with tribes and their representatives. 

Northern Cheyenne Reservation

CBNG activities that would be located off of the 

Northern Cheyenne Reservation would not directly 

impact cultural resources or sites located on the 

reservation. Cultural resources and sites located off 

of the reservation related to the Northern Cheyenne 

Tribe would be protected due to mitigation measures 
CHAPTER 4

Cultural Resources

4-67

that would relocate development activities to avoid 

cultural resources and sites. Consultation with the 

tribe would update knowledge about cultural 

resources and sites and improve the likelihood to 

avoid known cultural resources and sites. Information 

about these resources and sites is held confidential by 

the tribe and BLM which minimizes opportunities for 

the public to vandalize or steal cultural resources. 

With regards to off-reservation TCPs, the BLM has 

developed specific mitigation measures for protecting 

sites of religious and cultural concern to Native 

Americans. These measures have been developed in 

consultation with tribes and their representatives. 

These measures include provisions for information 

sharing and for the prevention of impacts to Northern 

Cheyenne homestead sites, traditional plant gathering 

sites, important hunting and fishing locations, 

culturally significant springs, grave sites and human 

remains. 

Conclusion

Under this Alternative, an estimated 893 to 1,080

cultural resource sites could be discovered during 

field surveys conducted before federal permits are 

approved and before surface disturbing activities 

occur for proposed TRR and CBNG exploration and 

production sites in the two RMP areas. Known 

cultural resources and sites would be protected by 

implementing mitigation measures and BMPs. 

Mitigation measures would be the same as those 

discussed in Chapter 2. Over the next 20 years, 

disturbances from CBNG development, conventional 

oil and gas development and other RFFA project 

activities could identify 5,398 to 5,585 cultural 

resource sites. Locating additional cultural resources 

would result in a better understanding of the nature 

and distribution of those resources. 

The Surface Transportation Board’s section of 

environmental analysis for its SEIS concluded that 

with mitigation neither the construction nor the 

operation of the TRR would result in significant

impacts to cultural resources.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Under this alternative, impacts to cultural resources 

would be similar to Alternative F except that they 

would be reduced by approximately 65 percent based 

on the fewer number of APDs that are predicted to be 

issued. Under this alternative an estimated 312 to 378 

cultural resource sites could be identified during field 

surveys conducted before surface disturbing activities 

occur for proposed CBNG exploration and 

production sites in the Planning Area. 

Crow Reservation

CBNG activities that would be located off of the 

Crow Reservation would not directly impact cultural 

resources or sites located on the reservation. Cultural 

resources and sites located off of the reservation 

related to the Crow Tribe would be protected because 

activities would be relocated to avoid cultural 

resources and sites. Consultation with the tribe would 

update knowledge about cultural resources and sites 

and improve the likelihood to avoid known cultural 

resources and sites. Information about these resources 

and sites is held confidential by the tribe and BLM 

which minimizes opportunities for the public to 

vandalize or steal cultural resources. With regards to 

off-reservation TCPs, the BLM has developed 

specific mitigation measures for protecting sites of 

religious and cultural concern to Native Americans. 

These measures have been developed in consultation 

with tribes and their representatives. 

Northern Cheyenne Reservation

CBNG activities that would be located off of the 

Northern Cheyenne Reservation would not directly 

impact cultural resources or sites located on the 

reservation. Cultural resources and sites located off 

of the reservation related to the Northern Cheyenne 

Tribe would be protected because activities would be 

relocated to avoid cultural resources and sites. 

Consultation with the tribe would update knowledge 

about cultural resources and sites and improve the 

likelihood to avoid known cultural resources and 

sites. Information about these resources and sites is 

held confidential by the tribe and BLM which 

minimizes opportunities for the public to vandalize or 

steal cultural resources. With regards to offreservation TCPs, the BLM has developed specific 

mitigation measures for protecting sites of religious 

and cultural concern to Native Americans. These 

measures have been developed in consultation with 

tribes and their representatives. These measures 

include provisions for information sharing and for the 

prevention of impacts to Northern Cheyenne 

homestead sites, traditional plant gathering sites, 

important hunting and fishing locations, culturally 

significant springs, grave sites and human remains. 

Conclusion

Under this Alternative, an estimated 312 to 378

cultural resource sites could be discovered during 

field surveys conducted before federal permits are 

approved and before surface disturbing activities 

occur for proposed TRR and CBNG exploration and 

production sites in the two RMP areas. Known 

cultural resources and sites would be protected 
CHAPTER 4

Cultural Resources

4-68

because activities would be relocated to avoid 

cultural resources and sites. Mitigation measures 

would be the same as those discussed in Chapter 2. 

Over the next 20 years, disturbances from CBNG 

development, conventional oil and gas development

and other cumulative effect analysis project activities 

could identify 4,817 to 4,883 cultural resource sites.

Locating additional cultural resources would result in 

a better understanding of the nature and distribution 

of those resources. 

Transportation Boards’ section of environmental 

analysis for their SEIS concluded that with mitigation

neither the construction nor the operation of the TRR 

would result in significant impacts to cultural 

resources.

Alternative H—Preferred Alternative - 

Multiple Screens

Under this alternative an estimated 893 to 1,080

cultural resource sites could be discovered during 

field surveys conducted before surface disturbing 

activities occur for proposed CBNG exploration and 

production sites in the Planning Area. Of these sites, 

the majority are predicted to be located in the Powder 

River RMP area. Locating cultural resource sites 

would result in the accumulation of additional 

artifacts and information. Impacts to cultural 

resources and sites identified before surface 

disturbing activities occur would be similar to those 

described in Alternatives B, C, D and E. Known 

cultural resources and sites would be protected by 

implementing mitigation and BMPs, such as locating 

CBNG activities to avoid cultural resources and sites.

Crow Reservation

CBNG activities that would be located off of the 

Crow Reservation would not directly impact cultural 

resources or sites located on the reservation. Cultural 

resources and sites located off of the reservation 

related to the Crow Tribe would be protected because 

activities would be relocated to avoid cultural 

resources and sites. Consultation with the tribe would 

update knowledge about cultural resources and sites 

and improve the likelihood to avoid known cultural 

resources and sites. Information about these resources 

is held confidential by the tribe and BLM which 

minimizes opportunities for theft and vandalism of 

cultural resources. With regards to off-reservation 

TCPs, the BLM has developed specific mitigation

measures for protecting sites of religious and cultural 

concern to Native Americans. These measures have 

been developed in consultation with tribes and their 

representatives. 

Northern Cheyenne Reservation

CBNG activities that would be located off of the 

Northern Cheyenne Reservation would not directly 

impact cultural resources or sites located on the 

reservation. Cultural resources and sites located off 

of the reservation related to the Northern Cheyenne 

Tribe would be protected because activities would be 

relocated to avoid cultural resources and sites. 

Consultation with the tribe would update knowledge 

about cultural resources and sites and improve the 

likelihood to avoid known cultural resources and 

sites. Information about these resources is held 

confidential by the tribe and BLM which minimizes 

opportunities for theft and vandalism of cultural 

resources. With regards to off-reservation TCPs, the 

BLM has developed specific mitigation measures for 

protecting sites of religious and cultural concern to 

Native Americans. These measures have been 

developed in consultation with tribes and their 

representatives. These measures include provisions 

for information sharing and for the prevention of 

impacts to Northern Cheyenne homestead sites, 

traditional plant gathering sites, important hunting 

and fishing locations, culturally significant springs, 

grave sites and human remains. 

Conclusion

Under this Alternative, an estimated 893 to 

1,080 cultural resource sites could be discovered 

during field surveys conducted before federal permits

are approved and before surface disturbing activities 

occur for proposed TRR and CBNG exploration and 

production sites in the two RMP areas. Known 

cultural resources and sites would be protected 

because activities would be relocated to avoid 

cultural resources and sites. Mitigation measures 

would be the same as those discussed in Chapter 2. 

Over the next 20 years, disturbances from CBNG 

development, conventional oil and gas development

and other cumulative effect analysis project activities 

could identify 5,398 to 5,585 cultural resource sites.

Locating additional cultural resources would result in 

a better understanding of the nature and distribution 

of those resources.

The Transportation Boards’ section on environmental 

analysis for their SEIS concluded that, with 

mitigation, neither the construction nor the operation 

of the TRR would result in significant impacts to 

cultural resources.
CHAPTER 4

Geology and Minerals

4-69

Geology and Minerals

Geology and Minerals

Montana’s mineral resources are intimately tied to the complex 

geologic framework of the state. Locatable minerals and 

conventional Oil and Gas resources are found throughout the 

Planning Area in various recoverable and non-recoverable 

amounts 

Alternative A

No Action (Existing CBNG Management)

• Federal:

− Only minor loss of CBNG during testing operations.

• State:

− Irretrievable commitment of CBNG resources from 

production on state planning areas.

− Delayed development or expansion of conventional 

oil and gas, coal mining and surface mineral mining 

in minor instances with no interruption to existing 

activities.

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Federal:

− Irretrievable commitment of CBNG resources from 

production, magnitude and complexity to reflect 

increase scale of development.

− Potential mineral drainage between federal mineral 

estates and state, private and tribal developments 

depending on site-specific conditions.

• State:

− Increased commitment of CBNG resources due to 

increased level of CBNG development.

− Mineral drainage issues same as for federal.

− The presence of shallow CBNG production could 

delay certain types of seismic prospecting for 

conventional oil and gas reservoirs

Alternative C

Emphasize CBNG Development

• Federal:

− Same as Alternative B with minor increase in water 

drawdown and potential operational interference 

within and adjacent to coal mines without the 1-mile 

buffer zone.

• State:

− Same as Alternative B.

− Potential mineral drainage between federal mineral 

estates and state, private, or tribal developments 

depending on site-specific conditions.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Federal:

− Same as Alternative B.

• State:

− Same as Alternative B.

− Potential mineral drainage between Federal mineral 

estates and state, private, or tribal developments 

depending on site-specific conditions.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Federal:

− Same as Alternative B with the addition of 

increased water drawdown and potential 

operational interference within and adjacent to coal 

mines without the 1-mile buffer zone.

− Protection of tribal CBNG from drainage because 

of resource protection protocols.

• State:

− Potential mineral drainage between federal mineral 

estates and state, private or tribal developments 

depending on site-specific conditions.

Alternative F

Phased Development Multiple Screens (High Range)

• Federal:

− Rate of development managed by limit set on the 

number of Federal APDs that would be approved per 

year

− Geographic development of CBNG resources 

managed through limits set on the number of federal 

APDs allowed for each 4th Order Watershed

− Limit on amount of untreated produced water from 

federal wells discharged within each 4th Order 

Watershed.

− Amount of acres disturbed in crucial habitat areas 

managed by limits associated with federal wells.

− Protection of tribal resources from federal wells 

within 5 miles of reservation boundaries. 

− Potential drainage of federal CBNG from production 

on state, private and tribal leases depending on sitespecific conditions, increased potential for drainage 

of federal CBNG due to the cumulative limit on the 

number of Federal APDs allowed per year.

− Potential drainage of federal CBNG underlying 

crucial sage-grouse habitat, or a reduction in the 

production of federal CBNG in crucial sage-grouse 

habitat if alternative development scenarios are 

implemented. 

• Potential operational interference within coal mine permit 

boundaries and adjacent to coal mines.

• State:

− Increased commitment of CBNG resources due to 

increased level of CBNG development.

− Potential drainage of the federal CBNG from 

production on state and private leases depending on 

site-specific conditions.

− Potential for drainage or lower levels of production 

from some private and state leases if operators 

cannot economically develop small tracts of these 

leases within the crucial sage-grouse habitat areas.

• The presence of CBNG production could delay certain 

types of seismic activities.

Alternative G

Phased Development Multiple Screens (Low Range)
CHAPTER 4

Geology and Minerals

4-70

• Federal:

− Rate of development managed by limit set on the 

number of Federal APDs that would be approved per 

year. 

− Geographic development of CBNG resources 

managed through limits set on the number of federal 

APDs allowed for each 4th Order Watershed.

− Limit on amount of untreated produced water from 

federal wells discharged within each 4th Order 

Watershed.

− Amount of acres disturbed in crucial habitat areas 

managed by limits associated with federal wells

− Protection of tribal resources from federal wells 

within 5 miles of reservation boundary.

− Potential drainage of the federal CBNG from 

production on state, private and tribal leases 

depending on site-specific conditions, increased 

potential for drainage of federal CBNG due to the 

cumulative limit on the number of Federal APDs 

allowed per year.

− Potential drainage of federal CBNG underlying 

crucial sage-grouse habitat, or a reduction in the 

production of federal CBNG in crucial sage-grouse 

habitat if alternative development scenarios are 

implemented.

− The presence of CBNG production could delay 

certain types of seismic activities

• State:

− Increased commitment of CBNG resources due to 

increased level of CBNG development.

− Potential drainage of the federal CBNG from 

production on state and private leases depending on 

site-specific conditions.

− Potential for drainage or lower levels of production 

from some private and state leases if operators 

cannot economically develop small tracts of these 

leases within the crucial sage-grouse habitat areas

• The presence of CBNG production could delay certain 

types of seismic prospecting for conventional oil and gas 

reservoirs

Alternative H

Preferred Alternative - Multiple Screens

• Federal:

− Rate of development managed by the number of 

Federal APDs that would be approved per year to 

protect other resources.

− Geographic development of CBNG resources 

managed by the location of federal APDs approved 

to protect other resources.

− Amount of acres disturbed in crucial habitat areas 

managed by limits associated with federal wells

− Protection of tribal resources from federal wells 

within 5 miles of reservation boundaries.

− Potential drainage of the federal CBNG from 

production on state, private and tribal leases 

depending on site-specific conditions, increased 

potential for drainage of federal CBNG due to the 

cumulative limit on the number of Federal APDs 

allowed per year.

− Potential drainage of federal CBNG underlying 

crucial sage-grouse habitat, or a reduction in the 

production of federal CBNG in crucial sage-grouse 

habitat if alternative development scenarios are 

implemented.

• The presence of CBNG production could delay certain 

types of seismic activities.

• Irretrievable commitment of CBNG resources from 

production, magnitude and complexity to reflect increase 

scale of development.

• Potential drainage of federal CBNG from production on 

state, private and tribal leases depending on site-specific 

conditions.

• Potential operational interference within coal mine permit 

boundaries and adjacent to coal mines.

• Protection of tribal CBNG from drainage by federal 

CBNG wells because of 5-mile buffer zone.

• The presence of CBNG production could delay certain 

types of seismic prospecting for conventional oil and gas 

reservoirs.

• State:

− Increased commitment of CBNG resources due to 

increased level of CBNG development.

− Potential mineral drainage of the federal mineral 

estates from production on state and private leases

depending on site-specific conditions.

Assumptions

Federal oil and gas leases would continue to be 

issued with standard lease terms and stipulations as 

identified by BLM. No Surface Occupancy (NSO), 

Controlled Surface Use (CSU) and Timing 

Restriction (Timing) stipulations provide protection 

to other resources from oil and gas lease activities. A 

detailed listing and description of stipulations are 

found in the Final Oil and Gas EIS/Amendment 

(BLM 1992).

• Federal APDs and Sundry Notices would 

continue to be issued with Conditions of 

Approval (COAs) as identified by BLM. COAs 

provide mitigation to minimize or eliminate 

impacts to other resources or land uses from oil 

and gas activities. COAs must conform to lease 

rights and land use decisions.

• BLM would continue to consult with private 

surface owners before approving oil and gas 

activities on private surface. Surface owner 

requirements can be incorporated as COAs.

• BLM would continue to require a certification 

that a signed agreement between the private 

surface owner and the CBNG operator exists 

before approving drilling operations on private 

surface.

• The Miles City Field Office and the Reservoir 

Management Group located in the Casper BLM 

Office would share drainage case information for 
CHAPTER 4

Geology and Minerals

4-71

cases within one mile of the Montana Wyoming 

state line.

• Other related Assumptions regarding typical 

CBNG operations are found at the beginning of 

this chapter.

Impacts From Management 

Common to All Alternatives

The production or drainage of oil and gas results in 

the irreversible and irretrievable loss of these 

resources. Oil and gas resources within a lease area 

can be directly removed by wells located on the lease 

area or drained by wells located adjacent to the lease 

when geologic conditions allow. Gas resources are 

irreversibly and irretrievably lost during venting or 

flaring operations. The cumulative impact to oil and 

gas resources would be a reduction in the known 

amount of these resources.

Existing BLM and State regulations allow for the 

production of oil and gas in a manner that conserves 

those resources so they are not wasted. Oil and gas 

production is guided by well spacing rules, field 

rules, lease development requirements and protective 

agreements such as communitization and unitization 

agreements. Flaring and venting operations must be 

conducted in accordance with agency approval, 

which also seeks to limit the wasting of gas resources 

as well as minimizing air quality and safety impacts.

CBNG development in Wyoming would result in 

drainage to Montana lands by wells just across the 

state boundary. The 80-mile-wide belt of the Powder 

River Basin that is prospective for CBNG would 

represent approximately 320 1/4-by-1/2-mile (80-

acre) spacing units draining resources (gas) from the 

adjacent state. Hydrocarbon (including CBNG) 

drainage is mitigated by regulations contained in 

43 CFR Parts 3100, 3106, 3108, 3130 and 3160. 

These regulations are meant to avoid waste and 

protect correlative mineral rights. Regulatory 

mechanisms include communitization agreements, 

protection well demands and compensatory royalties.

Oil and gas development would impact strippable 

coal resources in areas adjacent to existing coal 

mines or in new areas of coal mine interest. Oil and 

gas well bores and the production infrastructure 

would hinder the mining of coal in areas of oil and 

gas production.

BLM-issued oil and gas leases are issued with an 

NSO stipulation in an area with an active federal coal 

lease and an approved mine plan. The NSO 

stipulation prohibits surface occupancy and use for 

oil and gas lease operations. In areas outside of 

approved mine plans, BLM may issue both coal and 

oil and gas leases on the same parcel of land. BLM 

regulations support approval of applications from the 

first lessee, but also require lessees to resolve 

conflicts. Resolution of conflicts is further guided by 

BLM Instruction Memorandum WO-IM-2003-253

(BLM 2003a).

Conventional oil and gas lease operations would not 

impact CBNG resources because of the geology and 

well bore requirements. Migration of conventional oil 

and gas from source rocks to coal seams usually does 

not occur because of impermeable layers that exist

between the hydrocarbon bearing formations and the 

coal seams. The BLM and State require well bores to 

be completed with steel casing and cement in key 

locations of the well annulus to prevent the migration 

of fluids and drastically reduce the migration of 

hydrocarbons from one formation to another 

formation.

Conventional oil and gas wells and the associated 

infrastructure could be located on a lease area with 

CBNG wells and associated infrastructure.

Sand, gravel, or scoria needed for lease operations 

can be removed from BLM-administered surface by 

the operator from areas disturbed by lease operations 

under authority of the lease. Removal of sand, gravel, 

or scoria from BLM-administered surface by the 

operator outside of the area of disturbance for lease 

operations or removal by a third party would require 

a separate permit approved by BLM.

Methane migration due to CBNG extraction is a 

possibility but highly unlikely based on the nature of 

the Powder River Basin methane, the low-grade coals 

present in the basin and the geologic formations 

between the coal seams and the ground surface. 

These low-grade, low-strength coals do not support 

extensive fracturing that might give rise to methane 

seeps (GRI 2000). Furthermore, preliminary results 

of the on-going BLM Casper, Wyoming study, (see 

Chapter 3 geology and minerals discussion) do not 

indicate that seepage is occurring (Personal 

Communication, Dan Leeman, Mike McKinley and

Ed Heffern, November 2005).

The methane contained in Fort Union coals of the 

PRB is present in a free state, adsorbed on interior 

pore surfaces and micropores of the coal matrix and

dissolved in water contained within the coal seam. 

CBNG wells depressurize coals by producing water, 

as water production continues coals begin producing 

methane as the pressure drops below the local 

desorption pressure threshold. With continued water 

production, pressure around the CBNG wells drops 
CHAPTER 4

Geology and Minerals

4-72

Producing CBNG Wells Impacted 

Water 

Well

Ground Level

Ambient Water Level

Water level at onset of CH4 production

Net water movement CH4

CBNG Field 

Depressurization

Water Well 

Depressurization

Depressurized Water Level

and the depressurization front migrates out from the 

producing wells—as the front migrates outwards, net 

water movement is always toward the producing 

wells. Methane molecules and bubbles of gas will not 

migrate against the water flow within the coals. If a

water well or monitoring well produces methane, this 

suggests the methane is indigenous to coals around 

the well and was mobilized by the migration of the 

depressurization front. Figure 4-4 below illustrates 

the phenomenon of de-pressurization and methane 

drainage. 

Migration of methane is largely driven by water 

migration in the coal, operators report that migration 

within a well-managed CBNG field leads ultimately 

to drainage of between 40 and 80 acres per well, this 

is radial migration of 660 to 1320 feet over seven to 

ten or more years. 

Monitoring wells in the area of Decker, Montana 

have been impacted by methane production since 

before any CBNG wells were drilled in Montana; 

these wells were likely impacted by dewatering 

performed by the coal mines in the vicinity 

(Wheaton et al. 2006). Some monitoring wells 

produced gas as soon as they were completed, even 

though they were located considerably outside the 

influences of either coal mines or CBNG production. 

Outside of either coal mining or CBNG activities 

MBMG has recorded methane release for four 

monitoring wells. Since the arrival of CBNG 

production to the Montana portion of the PRB, more 

water wells and monitoring wells have been recorded 

with methane release. The MBMG maintains a 

database of water wells and monitoring wells which 

release methane; the database currently shows four 

wells have been influenced by coal mine de-watering 

and 16 wells by CBNG dewatering. Four of the 16 

wells released gas previous to CBNG development 

but have been noted to release more gas now 

(Wheaton et al. 2006).

Potential seepage areas may contain existing well 

bores and areas where faults, fractures, or sandstone 

layers occur in an orientation that provides a vertical

conduit for movement of methane from depressurized 

coals. Methane hazard areas have not been mapped or 

compiled within the Project Area. No estimate of 

seepage is available for the PRB.

Water well mitigation agreements currently in use in 

the PRB were reviewed to determine the 

effectiveness of these agreements to alleviate the 

impacts of methane migration and seepage. Typical 

agreements included a definition of well or water 

source impacts that included the increased presence 

of methane or changes in water quality. The 

agreements required the operator to reconfigure, 

redrill, or replace; the well or water source in such a

case. Access to another water source could also be

FIGURE 4-4 

DEPRESSURIZATION OF CBNG STRATA AND METHANE PRODUCTION
CHAPTER 4

Geology and Minerals

4-73

provided as a method to mitigate such impairment. 

The implementation of a Water Well Mitigation 

Agreement can be a method to rectify the effects to 

domestic water wells or springs from methane 

migration caused by CBNG production. 

BLM has the responsibility and authority to protect 

resources and land uses including public health and 

safety, from its authorized activities. BLM can 

impose requirements or restrictions on companies 

through conditions of approval included with 

approved permits. Implementation of conditions of 

approval should mitigate impacts to resources and 

land uses, including public health and safety. 

Mitigation measures could include cisterns or gas 

extractors that allow the water to de-gas. Water level 

manipulation by way of injection wells will likely be 

of little use in controlling methane. The water well 

may ultimately need to be plugged and water 

supplied to the land owner by another means such as 

a new well completed in a different coal. 

CBNG production may impact adjacent coal mines 

by increasing coal bed aquifer drawdown and by 

interfering with expansion of existing coal mines. 

However a symbiotic relationship could be 

established whereby the coal mine benefits from 

methane extraction prior to coal removal. The added 

dewatering from CBNG operations would 

beneficially affect the coal mines during production 

operations but could hinder and complicate aquifer 

restoration efforts once mining activities cease. In 

addition, the removal of coal seam water may create 

a situation where some coal mines would need to 

purchase water for dust control. Spring Creek Mine is 

a dry mine that does not produce water.

The drawdown of groundwater from coal seams 

would not damage the coal resource through 

compaction, nor would the likelihood of coal seam 

fires be greater than before. The circumstances for 

self-ignition of coal would not be present in the 

immediate vicinity of CBNG wells. During the 

production stage of CBNG activity, conditions 

essential to cultivate spontaneous combustion of coal 

such as oxidation, heat of wetting, airflow rate, coal 

particle size, pyrite content and temperature are not 

present. In fact, the design and construction of CBNG 

wells efficiently vents heat out of the coal so that 

temperatures needed for coal ignition are neither 

present nor anticipated. 

All oil and gas wells, including CBNG wells, must be 

plugged and abandoned when the wells are no longer 

capable of production or needed. The plugging 

procedure must be approved by either BLM or the 

state. Unlike abandoned underground coal mines, 

CBNG wells leave no underground voids vulnerable 

to further subsidence or associated spontaneous coal 

ignition. The probability of completely dewatering a 

coal bed and exposing large areas of fine coal 

particles to oxygen are unlikely due to the nature of 

producing CBNG in the PRB (Lyman and Volkmer 

2001). 

The presence of CBNG wells and the associated 

infrastructure could prevent certain types of seismic 

operations from being conducted in the area of 

CBNG production. The use of explosives could 

damage well bores or surface equipment and could 

damage the upper coal seam used for CBNG 

production.

The drawdown of groundwater from CBNG activities 

has been identified as the cause of surface subsidence 

in Wyoming (Case et al. 2000). The subsidence was 

recorded as 1/2 inch and represents a minimal impact 

to surface lands. In Montana where coal seams are 

thinner, subsidence would be less than what has been 

observed in Wyoming where coal seams are thicker.

Impacts From Management Specific 

To Each Alternative

Alternative A—No Action (Existing CBNG

Management)

Under this alternative, CBNG production would be 

limited by the number of wells that can be permitted 

for CBNG production by BLM and the State. The 

total number of producing CBNG wells is limited to 

250 by the terms of the Settlement Agreement 

affecting the State. The constraint is in place until the 

State has completed an EIS addressing the impacts 

from CBNG field development throughout the state. 

BLM is not approving the production of CBNG from 

federal wells until completion of the EIS, which 

addresses the impacts from CBNG field development 

in the Powder River and Billings RMP areas.

The production and venting of CBNG during the 

testing phase represent an irretrievable loss of that 

resource. Under the existing situation, CBNG may be 

drained from federal lands by producing CBNG wells 

on private and state leases. This drainage of federal 

CBNG represents an irretrievable loss of that 

resource. The venting of CBNG during coal mining 

represents the irretrievable loss of the resource.

Expansion of the Decker coal mine to the west and 

south and expansion of the Spring Creek coal mine to 

the south would be constrained by CBNG wells and 

the associated infrastructure of the CX Field. Mine 
CHAPTER 4

Geology and Minerals

4-74

expansion could occur after abandonment of the CX 

Field and removal of facilities and equipment.

Removal of groundwater by CBNG wells in coal 

seams that are being mined by Decker and Spring 

Creek could reduce the amount of groundwater 

flowing into the mine areas. Reduction in the amount 

of groundwater or degradation of groundwater 

quality by CBNG production would reduce the 

amount of groundwater available for domestic water 

wells from a particular coal seam. CBNG could 

migrate to domestic wells or escape at the surface 

from the removal of groundwater for CBNG

production.

Crow Reservation

Producing CBNG wells located within one mile of 

the Crow Reservation boundary could drain CBNG

resources from the Reservation. This drainage of 

Indian owned or privately owned CBNG would 

represent an irretrievable loss of the resource and a 

loss of royalties to the mineral owner. The location of 

CBNG wells and associated infrastructure on private 

and state lands could influence the location of future 

CBNG wells and associated infrastructure on lands 

within the Crow Reservation. This scenario is not 

anticipated under Alternative A because of the State 

Settlement Agreement. 

A detailed description of potential drainage impacts 

to Crow resources is found in the Environmental 

Justice section and a detailed description of potential 

impacts to groundwater from drawdown by CBNG

wells is found in the Hydrology section.

Northern Cheyenne Reservation

It is not anticipated any producing CBNG wells 

would be located within one mile of the Northern 

Cheyenne Reservation boundary and therefore 

drainage of tribal CBNG resources from the 

Reservation is not anticipated. 

Conclusion

The production of CBNG by state and private wells 

and the venting of CBNG represent the irreversible 

and irretrievable loss of the resource. The restrictions 

on the total number of CBNG wells approved for 

production reduces and delays associated revenues to 

lessees and government. The venting of CBNG

during coal mining represents the irreversible and 

irretrievable loss of the resource.

Production of CBNG should not impact the geology 

of the production area or any conventional oil and gas 

in the area of CBNG production. CBNG wells and 

the associated infrastructure would hinder the 

expansion of the Decker and Spring Creek coal mines 

toward the CX Field. The production of CBNG

would not prohibit the production of conventional oil 

and gas resources from the area of CBNG production. 

The production of conventional oil and gas in or 

around the CX Field would increase and intensify the 

impacts to other resources and on land uses.

The mitigation measures for this alternative would be 

similar to those described in Chapter 2.

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Under this alternative, the types of impacts 

experienced would be similar to those described 

under Alternative A, but increased because of 

expanded CBNG production on state, private and

BLM oil and gas lease areas. The increased 

development as part of this alternative would result in 

more CBNG production and the irretrievable 

commitment of more resources. Increased CBNG

production would amplify the opportunity for 

methane drainage from adjacent leases. Under this 

alternative, multiple coal seams would be developed 

from a single well bore. All coal seams would be 

developed at the same time and directional drilling 

for deeper coal seams would be required.

This alternative also includes a 1-mile buffer zone 

around active coal mines that would minimize the 

operational interference and water drawdown impacts 

from nearby CBNG production. Production of CBNG

would not be authorized on federal leases within a 

2-mile buffer zone in Montana along the Reservation 

boundary. The state may allow production of CBNG

from state leases within the buffer zone. The 

prohibition on the production of CBNG within the 

buffer zone would not apply to private leases within 

the buffer zone. 

The drawdown of groundwater from coal seams 

would not damage the coal resource present through 

compaction, nor would the likelihood of coal seam 

fires be greater than before. The circumstances for 

self-ignition of coal would not be present in the direct 

vicinity of CBNG wells in the emphasis area. During 

the production stage of CBNG activity, conditions 

essential to cultivate spontaneous combustion of coal 

such as oxidation, heat of wetting, airflow rate, coal 

particle size, pyrite content and temperature are not 

present. In fact, the design and construction of CBNG

wells efficiently vents heat out of the coal so that 

temperatures needed for coal ignition are neither 

present nor anticipated. 
CHAPTER 4

Geology and Minerals

4-75

After the coal seam is exhausted of economically 

recoverable methane resources, wells must be 

plugged and sealed. Unlike abandoned mines, CBNG

wells leave no underground voids vulnerable to 

further subsidence and associated spontaneous coal 

ignition. The probability of completely dewatering a 

coal bed and revealing large areas of fine coal 

particles to oxygen seem exceedingly remote (Lyman 

and Volkmer 2001). Further discussion regarding 

groundwater issues is contained in the Hydrology 

section of this chapter. 

The drawdown of groundwater from CBNG activities 

has been identified as the cause of surface subsidence 

in Wyoming (Case et al. 2000). The subsidence was 

recorded as 1/2 inch and therefore represents a 

minute impact to surface lands. In Montana where 

coal seams are thinner, subsidence would be less than 

what has been observed in Wyoming where coal 

seams are thicker.

Crow Reservation

Impacts to mineral resources on the Crow 

Reservation would be the same as described above in 

this alternative. Producing CBNG wells located 

within one mile of the Crow Reservation boundary 

could drain CBNG resources from the Reservation. 

This drainage of Indian owned or privately owned

CBNG would represent an irretrievable loss of the 

resource and a loss of royalties to the mineral owner. 

The location of CBNG wells and associated 

infrastructure on private and state lands could 

influence the location of future CBNG wells and 

associated infrastructure on lands within the Crow 

Reservation. Expanded CBNG development activities 

would increase the impacts and extraction of tribal

CBNG resources.

Northern Cheyenne Reservation

Impacts to mineral resources on the Northern 

Cheyenne reservation would be the same as described 

above in this alternative. Producing CBNG wells 

located within one mile of the Northern Cheyenne 

Reservation boundary could drain CBNG resources 

from the Reservation. This drainage of Indian owned 

or privately owned CBNG would represent an 

irretrievable loss of the resource and a loss of 

royalties to the mineral owner. The location of 

CBNG wells and associated infrastructure on private 

and state lands could influence the location of future 

CBNG wells and associated infrastructure on lands 

within the Crow Reservation. Expanded CBNG

development activities would increase the impacts 

and extraction of tribal CBNG resources. 

Conclusion

One of the cumulative impacts from this alternative 

would be increased production of CBNG from an 

increased number of producing wells including tribal

wells and from multiple coal seam development 

simultaneously. Multiple coal seam development 

simultaneously would result in the production of a 

higher rate of CBNG than single seam completions. 

Along with venting of CBNG during well testing, this 

would represent an irreversible and irretrievable loss 

of the resource.

The increased number of producing CBNG wells and 

the associated infrastructure could inhibit the 

expansion of existing coal mines, even with the 1-

mile buffer zone. This would delay or possibly 

preclude the mining of coal in certain areas. Areas of 

new coal mine interest would be excluded from 

opening new coal mines by the existence of 

producing CBNG wells and infrastructure.

The mitigation measures for this alternative would be 

similar to those described in Chapter 2. Additional 

mitigation measures include buffer zones around 

existing coal mines and simultaneous production of 

multiple coal seams through single well bores, 

subsurface injection of untreated water produced with 

CBNG and maximizing the number of producing 

CBNG wells connected to field compressors.

Alternative C—Emphasize CBNG

Development

Under this alternative, CBNG production could occur 

on state, private and BLM lease areas. Operators 

would not be required to produce CBNG

simultaneously from multiple coal seams through a 

single well bore. CBNG production from multiple 

coal seams could occur simultaneously through 

single well bores or simultaneously through separate 

well bores or different coal seams could be developed 

separately (staggered over time) or a combination of 

production methods. 

Allowing CBNG production from state, private and

BLM leases would increase the amount of CBNG

produced. Producing CBNG from multiple coal 

seams simultaneously would have impacts similar to 

those described in Alternative B. The potential for 

drainage of CBNG resources by producing CBNG

wells would increase with the increase in the number 

of producing wells. Directional drilling would not be 

required. Without directionally drilled wells, the 

impacts from vertical wells would be the same as 

Alternative A but increased for the scale of 

development.
CHAPTER 4

Geology and Minerals

4-76

CBNG production will impact adjacent coal mines by 

increasing coal bed aquifer drawdown and by 

interfering with expansion of existing coal mines. 

The added dewatering from CBNG operations would 

affect the coal mines by hindering and complicating 

aquifer restoration efforts the mine must perform 

once mining activities cease. In addition, the removal 

of coal seam water may create a situation where some 

coal mines would need to purchase water for dust

control.

The drawdown of groundwater does not represent an 

immediate impact to surface lands resulting from 

subsidence. The thinness of the coal seam aquifers 

and their shallow depth should prevent them from 

being substantially impacted by groundwater 

withdrawal and subsequent aquifer compaction.

Crow Reservation

Impacts on the Crow Reservation would be the same 

as described for the study area in general for 

Alternative C. However, without the 2-mile 

Reservation buffer zone, tribal CBNG resources 

would have an increased vulnerability to drainage 

from adjacent state, federal and private wells.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the study area 

under this Alternative. Furthermore, without the 2-

mile Reservation buffer zone, tribal CBNG resources 

would have an increased vulnerability to drainage 

from adjacent state, federal and private wells.

Conclusion

The cumulative impacts for this alternative would be 

similar to Alternative B with some exceptions. The 

removal of the requirement for a buffer zone around 

coal mines would result in increased drawdown and 

greater operational interference within the mines 

from CBNG production. After mining has ceased, the 

added dewatering will need to be remediated by the 

mine operators. Remediation bonds executed by the 

mine operators prior to operations will need to be 

honored. Unless the impact of the CBNG production 

can be separated from impacts by the coal mine, the 

remediation bond will force the mine operator to 

spend more money to remediate the aquifer. Coal 

mine operators may develop aquifer mitigation

agreements with CBNG operators prior to CBNG

production. The mitigation measures for this 

alternative would be similar to Alternative A.

Tribal development of CBNG resources on 

reservations would increase the irreversible and 

irretrievable loss of the resource.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Impacts from management objectives outlined in 

Alternative D would be similar to the impacts 

described under Alternative B.

Crow Reservation

Impacts to the Crow Reservation would be similar to 

impacts described in Alternative B.

Northern Cheyenne Reservation

Impacts to the Northern Cheyenne Reservation would 

be similar to impacts described in Alternative B.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Impacts to coal and existing coal mines would be the 

same as Alternative C because a buffer zone would 

not be required around existing coal mines.

Impacts to CBNG resources would be the same as 

Alternative B if all coal seams are produced 

simultaneously or to Alternative C if coal seams are 

produced separately. Impacts to CBNG production 

and wells would be the same as Alternative A 

because multiple seam production through a single 

well bore would not be required.

Impacts on conventional oil and gas resources would 

be the same as discussed in the Management 

Common section.

The production of CBNG and the venting of CBNG

represent the irreversible and irretrievable loss of the 

resource. Drainage by off-lease CBNG wells 

represents the irreversible and irretrievable loss of the 

resource and royalties to the lessee of the lease being 

drained.

For Alternative E, the Crow and Northern Cheyenne 

Reservation would be protected from drawdown of 

coal seam aquifers and drainage of tribal CBNG

resources as described in Chapter 2 of this document. 

To gauge incipient impacts related to groundwater 

and CBNG resource drainage on the Crow and 

Northern Cheyenne reservations, monitoring wells 
CHAPTER 4

Geology and Minerals

4-77

would be required to be installed during the 

exploration phase on all BLM-administered oil and 

gas leases that show hydrologic connectivity with the 

reservation aquifers. 

Crow Reservation

Impacts to the Crow Reservation from federal lease 

operators under Alternative E would be minimized. A 

buffer zone would not be established around the 

borders of the Reservation. However, other 

mitigation options would be available for 

consideration by the tribes. These include reducing 

production rates, shutting in the well or wells, 

payment of compensatory royalties, establishment of 

communitization agreements, or spacing to protect 

reservation CBNG resources from drainage. Under 

this alternative, there would be no drainage of tribal 

CBNG resources by federal lease operators. The 

potential for drainage by private lands within the 

reservation boundary and along the exterior boundary 

would still exist.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation from 

federal lease operators under Alternative E would be 

minimized. A buffer zone would not be established 

around the borders of the Reservation. The BLM has 

the responsibility to use reasonable means to prevent 

drainage of tribal CBNG caused by development on 

federal lands. Operators would be required to provide 

site-specific analyses prior to field development in 

areas of potential drainage to tribal CBNG resources. 

In these analyses, operators must demonstrate 

whether and to what extent federal CBNG production 

is likely to drain Reservation CBNG. The analysis 

would be used by BLM to determine the timing of 

CBNG production, monitoring requirements and

additional data needs.

If monitoring or reservoir modeling indicates 

drainage of CBNG resources is occurring, the BLM 

would enter negotiations with the operator and the 

tribe to protect the correlative rights of the tribe. 

BLM requirements could include reducing 

production rates, shutting in the well or wells, 

establishment of communitization agreements, or 

payment of compensatory royalty.

To protect the correlative rights of the tribe from state 

and private CBNG development, the BLM would 

represent the tribe at MBOGC hearings that set 

spacing units for the production of CBNG resources 

including state and private lands. The BLM would 

work with the MBOGC under its existing 

Memorandum of Understanding to protect tribal

resources that may be affected by state or private 

permits, or establishment of CBNG spacing units 

adjacent to tribal resources. Under this alternative, 

there would be no drainage of tribal CBNG resources 

by federal lease operators. The potential for drainage 

by private lands within the reservation boundary and 

along the exterior boundary would be minimized to 

the extent possible.

Conclusion

Under this alternative, cumulative impacts would be 

similar to Alternative B with the exception that 

injection of produced water would not be required. 

Injection of produced water into a subsurface 

formation approved by the state would be one water 

management option available to operators under this 

alternative and such disposal would not impact other 

mineral resources. Other produced water 

management options would be making produced 

water available for beneficial uses and treating, as 

needed, produced water before being discharged onto 

the surface or into bodies of water or used in 

managed irrigation. Impacts from produced water 

management options are described in other resource 

sections, such as hydrology and soils.

Alternative F—Phased Development 

Multiple Screens (High Range)

Under this alternative, impacts to CBNG resources 

would be similar to Alternative E except that they 

would be dispersed or spread out over time and place

by numerical limits for cumulative and watershed 

specific APDs that BLM would approve per year.

Impacts to coal and existing coal mines would be the 

same as Alternative C except they might be delayed 

or dispersed over time and place. The annual, 

calendar-based cumulative limit placed on federal 

APDs approved by BLM would be set at five percent

(910 APDs) of the high-range number of state, 

private and federal CBNG APDs (18,225) predicted 

to be approved in the RMP areas (as identified in the 

Reasonably Foreseeable Development scenario in the 

Statewide Document). A limit would also be 

established on the number of federal APDs that 

would be approved each year within each 4th Order 

Watershed. This limit would be set at the total 

number of wells predicted for each watershed times 

the predicted rate of development in the Statewide 

Document. These combined limits would serve to 

level the impacts over a 20-year development period. 

Imposition of phased development limits may impair 

the ability of some operators to develop their leases 

in a timely fashion due to the inability to obtain a 

sufficient number of federal APDs within a given 
CHAPTER 4

Geology and Minerals

4-78

year or timeframe to allow for development within a 

particular lease or area. This could result in a less 

orderly development of the gas resource and could 

result in lost or delayed revenue for the operators and 

other royalty interests. This less orderly development 

could also result in unintended environmental 

impacts due to possible increases in surface 

disturbance necessary to produce the wells.

Producing infrastructure for the wells may have to 

bypass certain areas and then additional infrastructure 

installed later as wells are drilled.

The production of CBNG and the venting of CBNG 

represent the irreversible and irretrievable loss of the 

resource. Drainage of federal CBNG by off-lease 

CBNG wells represents the irreversible and 

irretrievable loss of the federal resource and royalties 

to the lessee as well as the federal government and 

state of Montana. Under Alternative F, watershed 

specific and cumulative numerical limits would be 

placed on the number of federal APDs approved each 

year. This could result in the situation where state 

and private leases that adjoin federal leases could 

experience CBNG resource development for a 

number of years prior to federal APDs being 

approved for the federal leases. For example, state 

and private APDs could use the majority of annually 

approved APDs (ratio 80 percent: 20 percent) for the 

first several years resulting in a disproportionate 

development pattern in the field. This would result in 

a delay of CBNG resources developed on federal 

leases. The development occurring on adjoining state 

or private leases would increase the potential for 

drainage of federal minerals and may cause wells on 

federal minerals to be uneconomic and not drilled. 

The lack of equitable and concurrent federal 

development would result in a loss of royalty income 

to the federal government as well as the state portion 

and a loss of income to the lessee of the federal lease. 

There are currently 120 wells drilled on federal 

minerals within the CX Field. As a result of an Order 

issued by the U.S. District Court for Montana, 

restrictions were imposed upon BLM regarding the 

annual number of CBNG APDs that can be approved 

by BLM during preparation of the FSEIS. 

Subsequent to the District Court Order, the Ninth 

Circuit Court of Appeals issued an injunction which 

prohibited BLM from approving any permits for the 

production of CBNG in the Montana portion of the 

PRB. These restrictions resulted in extended delays 

to approximately five percent of the federal APDs 

submitted. Drilling and development of adjoining 

state and private minerals has continued and it is 

likely that the five percent federal mineral locations 

are being drained and may no longer be economical 

to drill. For Alternative F, if five percent of the 

proposed wells were not drilled because of 

restrictions on the number of annual APDs approved, 

a total of 425 wells would not be drilled representing 

a loss of approximately 127.5 billion cubic feet 

(BCF) of natural gas to the Federal Government. This 

would be a loss of income to the lessees of the federal 

leases and a loss of royalty to the federal government 

and to county governments. 

For years 1 thru 9 of phased development under 

Alternative F, the number of state and private APDs 

issued would be greater than the number of 

federal/BLM APDs issued. In years 3, 4 and 5 it is 

predicted that no federal/BLM APDs would be 

issued. It is this situation that creates the increased 

potential to drain federal minerals from production on 

adjoining state and private minerals.

For Alternative F, the Crow and Northern Cheyenne 

reservations would be protected from drawdown of 

coal seam aquifers and drainage of tribal CBNG 

resources from federal CBNG wells by the 

establishment of a 5-mile buffer zone around the 

borders of the Crow and Northern Cheyenne 

reservations, except along the common border of the 

two reservations. Resource protection protocols that 

demonstrate protection of Indian groundwater and 

CBNG would be required to be included in each 

operator’s POD that includes the development of 

federal CBNG wells within the 5-mile buffer zone. If 

the development of federal minerals within the 5-mile 

buffer zone is delayed or restricted while 

development on state and private leases continue, 

then the situation develops where there would be the 

increased potential for drainage of federal minerals.

CBNG Indian resources could be impacted by 

development of state and private leases within the 5-

mile buffer zone. 

Within the 5-mile buffer zone of a reservation 

boundary, BLM managed minerals represent 24

percent (127,165 acres) of total mineral ownership 

(463,118 acres) within the Billings RMP Area and 64

percent (250,565 acres) of total mineral ownership 

(355,307 acres) within the Powder River RMP Area.

These federal minerals could contain as much as 1.4 

TCF of gas that may be lost to the federal and county 

governments [(127,165 acres + 250,565 acres)/1 well 

per 80 acres * 0.3BCF per well]. These statistics do 

not take into account the federal minerals 

administered by the Custer National Forrest, Ashland 

Ranger District. 

The buffer could also cause a reduction in the 

development of federal leases due to the increased 

economic investment required to develop CBNG 

within the zone. Additional costs include installation 

of added monitoring wells and air monitoring stations
CHAPTER 4

Geology and Minerals

4-79

and additional geologic engineering work to 

demonstrate that the CBNG production would have 

no impact on Indian Trust Assets (ITAs). 

Furthermore, if companies were required to

temporarily or permanently cease production of 

CBNG wells because of a perceived or established 

impact to ITAs, the decision could affect production 

of CBNG from any federal lease within the five mile 

buffer. It is unlikely that companies would be willing 

to invest capital in drilling and developing a lease if 

they are not guaranteed an opportunity to recover the 

capital investment and make a reasonable profit for 

their shareholders. This could also result in a scenario 

where the federal tracts in the buffer area may be 

leased but would be viewed as having a lesser value 

than a private or state lease that did not contain these 

same restrictions/requirements. If the lessees of the 

federal leases in the buffer area were not allowed to 

pursue development of the lease, a case might be 

made for a "taking" of their rights as lessee.

Under this alternative, restrictions applied to the

development of federal CBNG in crucial sage-grouse 

habitat areas would likely lead to some level of 

drainage of federal CBNG from adjacent state and 

private wells and may actually cause some drainage 

impacts to private and State mineral estate. This is 

because the allowable development within the crucial 

sage-grouse habitat areas is likely to be less efficient 

in the recovery of the CBNG resource. If no 

development were to occur on Federal mineral estate 

within these areas, some small isolated tracts of 

private or State minerals would be considered 

uneconomic to develop and would be subject to 

drainage, or not developed. 

A “no development” outcome would lead to a loss of 

Federal royalties. For an estimate of Federal royalties 

lost due to “no development” see the socioeconomic 

section. Similarly, private and State mineral estates 

would lose royalties. The no development outcome is 

considered unlikely and is used for comparing 

impacts between full development and no 

development within the crucial sage-grouse habitat 

areas.

Crow Reservation

CBNG resources of the Crow Tribe would be 

protected from production of federal CBNG through 

the establishment of a 5-mile buffer zone on the east, 

west and north sides of the reservation. The BLM has 

the responsibility to use reasonable means to prevent 

drainage of tribal groundwater and CBNG resources. 

Within the 5-mile buffer zone surrounding the Crow 

Reservation, BLM would require the operator to 

demonstrate the protection of Indian resources in the

POD. The operator’s analyses would need to 

demonstrate if Indian minerals and groundwater 

would be impacted by development of federal CBNG 

wells. If groundwater and minerals might be 

impacted, the POD must include resource protection 

protocols for these assets. If the POD does not show 

protection of Indian Trust Assets and adequate 

resource protection protocols are not included, BLM 

would not approve the APD. 

Resource protection protocols could include a 

requirement for monitoring wells to be installed 

between the development area and the reservation. If 

monitoring indicates that Indian minerals are not 

being protected, then CBNG development wells 

would be shut-in. If CBNG development occurs on a 

reservation, this requirement may be modified in 

consultation with the tribe and other affected parties. 

Other resource protection protocols that could be 

considered to protect reservation groundwater and 

CBNG resources from drainage include reducing 

federal CBNG well production rates, establishment of 

communitization agreements in consultation with the 

tribe, or adjusting CBNG well spacing requirements. 

Under this alternative, there would be no drainage of 

tribal CBNG resources by federal CBNG wells. The 

potential for drainage of undeveloped federal and 

Indian leases by development of state and private 

leases along the exterior boundary would still exist.

Northern Cheyenne Reservation

A buffer zone would be established on the south, 

north and east sides of the Reservation. The 

protection of Indian minerals and groundwater for the 

Northern Cheyenne Tribe would be the same as 

described for the Crow Tribe with the exception of 

drainage of Indian CBNG from the drilling of private 

leases within the reservation because the tribe owns 

the majority of minerals within the reservation. 

Conclusion

Under this alternative, cumulative impacts would be 

similar to Alternative E with the exception that 

impacts would be dispersed or spread out over time 

and place due to the implementation of cumulative 

and watershed specific numerical limits on the 

number of federal CBNG APDs approved per year. 

Delays in the development of CBNG resources on 

federal leases could result in the increased potential 

for drainage of federal minerals due to the 

development of CBNG resources on adjoining state 

or private leases. This alternative could lessen the 

value of federal leases because of drainage occurring 

from offsetting private and state wells that would 
CHAPTER 4

Geology and Minerals

4-80

never be recovered. Conflicts could arise between 

lessees over who can develop first, or at all and the 

resultant loss of revenue to the lessee. This 

alternative could also require the federal government 

to extend leases beyond their primary term without 

production due to the government not allowing 

timely development.

Indian CBNG and groundwater would be protected 

from production of federal CBNG wells through the 

implementation of a 5-mile buffer zone within which 

operators would be required to conduct site-specific 

analyses and develop resource protection protocols 

that would be included with their PODs for any 

CBNG wells to be drilled on federal leases. The 

buffer zone and protection protocols would not apply 

to wells approved by the state which could result in 

direct and indirect impacts to groundwater and 

CBNG located under the reservations. 

Alternative G—Phased Development 

Multiple Screens (Low Range)

Under this alternative, impacts to CBNG resources 

would be similar to Alternative F except that they 

would be reduced by approximately 65 percent based 

on the fewer number of APDs that are predicted to be 

issued. Under Alternative G, the annual cumulative 

limit placed on federal APDs approved by BLM 

would be set at five percent (323 APDs) of the lowrange number of state, private and federal CBNG 

APDs (6,470) predicted to be approved in the RMP 

areas (as identified in the Reasonably Foreseeable 

Development scenario in the Statewide Document). 

A limit would also be established on the number of 

federal APDs that would be approved each year 

within each 4th Order Watershed. This limit would 

be set at the total number of wells predicted for each 

watershed times the predicted rate of development in 

the Statewide Document These combined limits 

would serve to level the impacts over a 20-year 

development period. 

Since the annual rate of development would be 

limited to five percent of the cumulative APDs 

predicted, the potential for the drainage of federal 

minerals from production on adjacent or adjoining 

state or private leases would be the same as for

Alternative F. In years 1 through 9, the number of 

state and private APDs issued would be greater than 

the number of federal/BLM APDs issued and in years 

three, four and five when it is predicted that no 

federal/BLM APDs would be issued. This would 

create the potential for an increase in the drainage of

federal CBNG by production on adjacent state and 

private leases. Applying the same example as 

outlined under Alternative F, if five percent of federal 

CBNG wells are not drilled this would represent 

approximately 150 wells and a loss of approximately

45 BCF of natural gas from federal leases. This 

would be a loss of income to the lessees of the federal 

leases and a loss of royalty to the federal government 

and the counties and state of Montana.

Imposition of phased development limits may impair 

the ability of some operators to develop their leases 

in a timely fashion due to the inability to obtain a 

sufficient number of APDs within a given year or 

timeframe to allow for development within a 

particular lease or area. This could result in a less 

orderly development of the gas resource and could 

result in lost or delayed revenue for the operators and 

other royalty interests. This less orderly development 

could also result in unintended environmental 

impacts due to possible increases in surface 

disturbance necessary to produce the wells.

Producing infrastructure for the wells may have to 

bypass certain areas and then additional infrastructure 

installed later as wells are drilled.

For Alternative G, a 5-mile buffer zone would be 

established around the borders of the Crow and 

Northern Cheyenne reservations. Resource protection 

protocols and potential impacts, including the 

increased potential for the drainage of federal minerals 

due to delayed or restricted development of federal 

leases, would be the same as for Alternative F. 

Crow Reservation

Impacts to the Crow Reservation would be similar to 

impacts described in Alternative F. 

Northern Cheyenne Reservation

Impacts to the Northern Cheyenne Reservation would 

be similar to impacts described in Alternative F. 

Conclusion

Under this alternative, cumulative impacts would be 

similar to Alternative F except that they are expected 

to be less due to approximately 65 percent fewer 

APDs being issued. Impacts would be dispersed or 

spread out over time and place due to the 

implementation of cumulative and watershed specific 

numerical limits on the number of federal CBNG 

APDs approved per year. Delays in the development 

of CBNG resources on federal leases could result in 

the increased potential for drainage of federal 

minerals due to the development of CBNG resources 

on adjoining state or private leases. This alternative 

could lessen the value of federal leases because of 

drainage occurring from offsetting private and state 

wells that would never be recovered. Conflicts could 
CHAPTER 4

Geology and Minerals

4-81

arise between lessees over who can develop first, or 

at all and the resultant loss of revenue to the lessee. If 

lessees are not allowed to develop the gas resources 

this would result in a loss of the resource to the 

nation. This alternative could also require the federal 

government to extend leases beyond their primary 

term without production due to the government not 

allowing timely development.

ITAs would be protected through the implementation 

of a 5-mile buffer zone within which operators would 

be required to conduct site specific analyses and 

develop mitigation measures and monitoring that 

would be included with their POD for any CBNG 

wells to be drilled on federal leases. The buffer zone 

and mitigation measures would not apply to wells 

approved by the state which could result in direct and 

indirect impacts to groundwater and CBNG located 

under the reservations. 

Alternative H—Preferred Alternative - 

Multiple Screens

Under this Alternative, impacts to federal leases, 

CBNG resources and federal lessees would be similar 

to Alternative F. This Alternative manages the pace 

(rate) and place (geography) of federal CBNG 

development through protection measures applied to 

crucial habitat areas and limits to the discharge of 

untreated produced water from federal CBNG wells 

and emissions from sources associated with federal 

CBNG wells. More federal APDs could be approved 

annually and geographically than under Alternatives 

F and G as long as other resources are protected. 

Monitoring data would be required to help BLM 

determine which (where and when) federal APDs 

could be approved. These limits and thresholds (see 

Wildlife Appendix and Hydrology section) would 

serve to level the cumulative impacts over time. The 

production of CBNG would continue for a longer 

overall period of time compared to Alternative E 

because fewer number of federal CBNG wells may 

be drilled each year. 

The production and venting of CBNG represents the

irreversible and irretrievable loss of the resource; 

although the production of CBNG makes it available 

in the market place. Drainage of federal CBNG by 

off-lease CBNG wells represents the irreversible and 

irretrievable loss of the federal resource and loss of

revenue to the operator, lessee, federal government

and state of Montana. 

Imposition of phased development limits may impair 

the ability of some operators to develop their leases 

in a timely fashion due to the inability to obtain a 

sufficient number of approved APDs within a given 

year or timeframe to allow for development within a 

particular lease or area. This could result in a less 

orderly development of the gas resource and could 

result in lost or delayed revenue for the operators, 

lessees, the federal government and state of Montana.

This less orderly development could also result in 

unintended environmental impacts due to possible 

increases in surface disturbance necessary to produce 

the wells. Producing infrastructure for the wells may 

have to bypass certain areas and then additional 

infrastructure installed later as wells are drilled.

Under this alternative, restrictions applied to the 

development of federal leases in crucial sage-grouse 

habitat areas would likely lead to some level of 

drainage of federal CBNG from adjacent state and 

private wells and may actually cause some drainage

impacts to private and State mineral estate. This is 

because the allowable development within the crucial 

sage-grouse habitat areas is likely to be less efficient 

in the recovery of the CBNG resource. If no 

development were to occur on federal leases within 

these areas, some small isolated tracts of private or 

State minerals would be considered uneconomic to 

develop and would be subject to drainage, or not 

developed. 

A “no development” outcome would lead to a loss of 

Federal royalties. For an estimate of Federal royalties 

lost due to “no development” see the socioeconomic 

section. Similarly, private and State mineral owners

would lose royalties. The no development scenario

compares impacts between full development and no 

development within the crucial sage-grouse habitat 

areas.

Under Alternative H, the Crow and Northern 

Cheyenne reservations would be protected from 

drawdown of groundwater in coal seams and 

drainage of tribal CBNG from federal CBNG wells

by the establishment of a 5-mile buffer zone around 

the borders of the reservations and implementation of 

mitigation measures associated with federal CBNG 

wells within the 5-mile zone. Mitigation measures 

that demonstrate protection of Indian minerals and 

groundwater would be required to be included in 

each operator’s POD that includes the development 

of federal CBNG wells within the 5-mile buffer zone. 

If the development of federal minerals within the 5-

mile buffer zone is delayed or restricted while 

development on state and private leases continue, 

then the situation develops where there would be the 

increased potential for drainage of federal minerals. 

Within the 5-mile buffer zone of a reservation 

boundary, BLM managed minerals represent 24

percent (127,165 acres) of total mineral ownership 

(463,118 acres) within the Billings RMP Area and 64
CHAPTER 4

Geology and Minerals

4-82

percent (250,565 acres) of total mineral ownership 

(355,307 acres) within the Powder River RMP Area.

These federal minerals could contain as much as 1.4

to 1.6 TCF of gas[(127,165 acres + 250,565 acres)/1 

well site per 80 acres * 0.3 to 0.34 BCF per well site]. 

If federal leases within the 5-mile zone are not fully 

developed, the gas resource may be produced by 

adjacent state and private CBNG wells or not fully 

recovered. This would also result in lower revenues 

to the lessee and federal, state and county 

governments. For an estimate of Federal royalties lost 

due to “no development” see the socioeconomic 

section.

The buffer could also cause a reduction in the 

development of federal leases due to the increased 

economic investment required to develop CBNG 

within the zone. Additional costs include installation 

of added monitoring wells and air monitoring stations

and additional geologic engineering work to 

demonstrate that the CBNG production would have 

no impact on ITAs. Furthermore, if companies were 

required to cease production of CBNG wells because 

of a perceived or established impact to ITAs, the 

decision could affect production of CBNG from any 

federal lease within the 5 mile buffer. It is unlikely 

that companies would be willing to invest capital in 

drilling and developing a lease if they are not 

guaranteed an opportunity to recover the capital 

investment and make a reasonable profit for their 

shareholders. This could also result in a scenario 

where tracts in the buffer area may be leased but 

would be viewed at a lesser value than a private or 

state lease that did not contain these same 

restrictions/requirements. If the lessees of the federal 

leases in the buffer area were not allowed to pursue 

development of the lease, a case might be made for a 

"taking" of their rights as lessee.

Impacts on conventional oil and gas resources would 

be the same as discussed in the Management 

Common section.

Crow Reservation

CBNG resources of the Crow Tribe would be 

protected through the establishment of a 5-mile 

buffer zone around the east, west and north sides of 

the reservation. The BLM has the responsibility to 

use reasonable means to prevent drainage of tribal

CBNG and groundwater resources. Within the 5-mile 

buffer zone surrounding the Crow Reservation, BLM 

would require site-specific analyses be included with 

the operator’s POD. The operator’s analyses would 

need to demonstrate if Indian minerals and 

groundwater would be impacted by development of 

federal CBNG wells. If groundwater and minerals 

might be impacted, the POD must include resource 

protection protocols for these assets. If the analyses 

do not show protection of ITAs and adequate 

resource protection protocols are not identified 

during consultation with the tribe, BLM would not 

approve the APD. 

Resource protection protocols could include a 

requirement for monitoring wells to be installed 

between the development area and the reservation. If 

monitoring indicates that Indian minerals or 

groundwater are not being protected, then 

consultation with the tribe would be conducted to 

determine a suitable mitigation measure, or CBNG 

development wells could be shut-in. If CBNG 

development occurs on the reservation, this 

requirement may be modified in consultation with the 

tribe and other affected parties. 

Other resource protection protocols that could be 

considered to protect reservation groundwater and 

CBNG resources from drainage include reducing 

federal CBNG well production rates, establishment of 

communitization agreements in consultation with the 

tribe, or adjusting CBNG well spacing requirements. 

Under this alternative, there would be no drainage of 

tribal CBNG resources by federal lease operators. 

The potential for drainage of undeveloped federal 

minerals by development of private leases within the 

reservation buffer zone and development of state and 

private leases along the exterior boundary would still 

exist. 

Northern Cheyenne Reservation

A buffer zone would be established on the south, 

north and east sides of the Reservation. The 

protection of Indian minerals and groundwater for the 

Northern Cheyenne Tribe would be the same as 

described for the Crow Tribe with the exception of 

drainage of Indian CBNG from the drilling of private 

leases within the reservation because the tribe owns 

the majority of minerals within the reservation. 

Conclusion

The cumulative impacts under this alternative would 

include production of CBNG from more federal wells 

drilled annually than under Alternatives F and G, but 

probably fewer federal wells drilled annually than 

under Alternative E. This would result in an overall 

longer period of time to produce CBNG in the 

Planning Area compared to Alternative E and

probably a shorter overall period of time compared to 

Alternatives F and G. CBNG production represents 

the recovery of the resource for the nation and 
CHAPTER 4

Geology and Minerals

4-83

revenue for federal, state and local governments, 

companies and individuals. 

Delays in the development of CBNG resources on 

federal leases could result in the increased potential 

for drainage of federal CBNG due to the 

development of CBNG resources on adjoining state 

or private leases. This alternative could lessen the 

value of federal leases because of drainage occurring 

from offsetting private and state wells that would 

never be recovered. Conflicts could arise between 

lessees over who can develop first or at all and the 

resultant loss of revenue to the lessee. This 

alternative could also require the federal government 

to extend leases beyond their primary term without 

production due to the government not allowing 

timely development

The increased number of producing CBNG wells and 

the associated infrastructure located near coal mine 

permit boundaries could inhibit the expansion of 

existing coal mines. This could delay or possibly 

preclude the mining of coal in certain areas. Areas of 

new coal mine interest would be excluded from 

opening new coal mines by the existence of 

producing CBNG wells and infrastructure.

Furthermore, CBNG related impacts particularly 

from federal wells would be dispersed or spread out 

over time and place due to the implementation of 

BLM imposed restrictions or “screens” previously 

described. 

Indian groundwater and minerals would be protected 

through the implementation of a 5-mile buffer zone 

within which operators would be required to conduct 

site-specific analyses and develop resource protection 

protocols that would be included with their PODs for 

any CBNG wells to be drilled on federal leases. If the 

operators cannot demonstrate that there would be no 

impact to the Indian groundwater and minerals, their 

APDs would not be approved. This would result in a 

loss of the gas resource to the nation. The buffer zone 

and protection protocols would not apply to wells 

approved by the state which could result in direct and 

indirect impacts to groundwater and CBNG located 

under the reservations. 
CHAPTER 4

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4-84

Hydrological Resources

Hydrological Resources

Surface water: Some surface waters in the Powder River Basin 

are of good quality and frequently used for irrigation. Other 

rivers are characterized as having fair to poor quality water 

and may go dry, the waters are used for stock and limited 

irrigation. 

Groundwater: Groundwater is available in stream bottom 

alluvium, but becomes scarce away from water courses. Coal 

beds and interlayered sands are the most commonly used 

aquifers away from riparian areas. Groundwater quality is 

variable. 

Alternative A

No Action (Existing CBNG Management) 

• Federal:

− No impacts to surface or groundwater resources 

• State:

− Negligible changes in Tongue River quality and 

flow. 

− Groundwater drawdown within the immediate 

vicinity of the CX Ranch 

− Continued beneficial reuse of produced water at the 

CX Ranch

• Cumulative Impacts:

− Surface Water: 

Wyoming CBNG discharges will result in moderate

increases in flow and changes in water quality in 

rivers shared between Montana and Wyoming, 

however downstream uses will not be diminished

- Tongue River Railroad construction could lead to 

localized soil erosion and impact to surface water 

focused run-off, localized increased stream flow and

increased suspended sediment. 

− Groundwater:

Drawdown from Wyoming CBNG and the CX 

Ranch may extend several miles from development.

− Beneficial Reuse:

Wyoming and CX Ranch discharges may increase 

opportunities for beneficial use.

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Surface Water

− Similar to Alternative A, potential for increased 

sediment loads due to soil disturbance and erosion.

• Groundwater:

− Drawn down will occur over large continuous areas

− Immediate drawdown will be minor. However, as 

CBNG production matures, coal seam aquifer 

drawdown may extend 4 to 5 miles from the edge of 

production

− No change in groundwater quality 

• Beneficial Reuse:

− Same as Alternative A

• Cumulative Impacts:

− Surface water flow and quality will be the same as 

Alternative A

− Montana and Wyoming CBNG production will 

noticeably drawdown coal seam aquifers

− Groundwater quality in Montana and beneficial 

reuse will be the same as Alternative A

Alternative C

Emphasize CBNG Development

• Surface Water

− Water quality in some watersheds will be noticeably 

altered. 

− Flows will be considerably increased.

• Groundwater:

− Drawdown similar to Alternative B.

− Alluvial groundwater quality may be altered due to 

infiltration of untreated production water

• Beneficial Reuse:

− Same as Alternative A

• Cumulative Impacts: 

− Surface water quality in some watersheds will be 

noticeably altered. 

− Flows will be considerably increased.

− Impacts to groundwater drawdown, quality and 

beneficial reuse will be the same as in Alternative B 

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Surface Water

− Similar to Alternative A, potential for increased 

sediment loads due to soil disturbance and erosion.

− Flows will increase similar to Alternative C

• Groundwater:

− Drawdown same as Alternative B

− No groundwater quality impacts

• Beneficial Reuse:

− Increased beneficial uses, estimated at 20 percent of 

production

• Cumulative Impacts: 

− Surface water quality will be slightly altered due to 

Wyoming CBNG discharges.

− Surface water flows will be similar to Alternative C 

− Groundwater drawdown and quality changes will be 

the same as in Alternative B

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses 

• Surface Water

− Water quality will be slightly altered, however 

beneficial uses will not be diminished 

− Flows will be moderately increased

• Groundwater:

− Drawdown same as Alternative B.

− Alluvial groundwater quality may be altered due to 

infiltration of untreated production water

• Beneficial Reuse:

− Required Water Management Plans from all 

operators will result in beneficial reuse of 

approximately 20 percent of production

• Cumulative Impacts: 

− Cumulative impacts to surface waters will be 

reduced dependent on MDEQ numerical standards

− Surface water quality will be slightly altered 

however downstream uses will not be diminished 

− Surface water flows will be moderately increased 

− Groundwater drawdown will be similar to 

Alternative B 

− Shallow groundwater quality may be slightly altered 
CHAPTER 4

Hydrological Resources

4-85

Alternative F

Phased Development Multiple Screens (High Range)

• Surface Water:

− Water quality will be slightly altered, however 

beneficial uses will not be diminished

− Flows will be moderately increased

• Groundwater:

− Drawdown same as Alternative B

• Beneficial Reuse:

− Required Water Management Plans from all 

operators will result in beneficial reuse of 

approximately 20 percent of production water

• Cumulative Impacts:

− Cumulative impacts to surface waters will be less 

than MDEQ standards.

− Surface Water quality will be slightly altered,; 

however downstream uses will not be diminished

− Surface water flows will be moderately increased

− Groundwater drawdown would be similar to 

Alternative B

− Conditions placed on CBNG federal mineral 

development within crucial sage-grouse habitat may 

reduce the overall number of CBNG wells 

developed. If no development occurs within the 

crucial sage-grouse habitat, the number of wells and

associated produced water, would be reduced by 

12.8%.

Alternative G

Phased Development Multiple Screens (Low Range)

• Surface Water:

− Water quality will be slightly altered, however 

beneficial uses will not be diminished

− Flows would slightly increase

• Groundwater:

− Drawdown effects near CBNG fields would be the 

same as Alternative B, but fewer CBNG fields 

would be developed

• Beneficial Reuse:

− Required Water Management Plans from all 

operators will result in beneficial reuse of 

approximately 20 percent of production water

• Cumulative Impacts:

− Cumulative impacts to surface waters will be less 

than MDEQ standards.

− Surface Water quality will be slightly altered,; 

however downstream uses will not be diminished

− Surface water flows will be slightly increased

− Drawdown effects near CBNG fields would be the 

same as Alternative B, but fewer CBNG fields 

would be developed

Alternative H 

Preferred Alternative - Multiple Screens

• Surface Water:

- Water quality will be slightly altered, however 

beneficial uses will not be diminished

- Flows will be moderately increased

• Groundwater:

- Drawdown same as Alternative B

• Beneficial Reuse:

- Required Water Management Plans from all operators 

will result in beneficial reuse of approximately 20

percent of production water

• Cumulative Impacts:

- Cumulative impacts to surface waters will be less 

than MDEQ standards.

- Surface Water quality will be slightly altered,; 

however downstream uses will not be diminished

- Surface water flows will be moderately increased

- Conditions placed on CBNG federal mineral 

development within crucial sage-grouse habitat may 

reduce the overall number of CBNG wells developed. 

If no development occurs within the crucial sagegrouse habitat, the number of wells and associated 

produced water, would be reduced by 12.8%.

The key water quality parameters for predicting the 

potential effects of CBNG development on irrigated 

agriculture are sodicity (as sodium adsorption ratio, 

SAR) and salinity (as electrical conductivity, EC). 

The MDEQ believes irrigated agriculture is the most 

sensitive beneficial use for surface waters in the 

study area, thus protection of irrigated agriculture 

will be sufficient to protect all other beneficial uses. 

Instream numerical targets for these parameters are 

used to model environmental impacts. 

The water quality standards for EC and SAR were 

adopted in 2003 by the Montana Board of 

Environmental Review (BER) to protect the most 

salinity-sensitive beneficial use of the streams and 

rivers in Montana's Powder River Basin, i.e., irrigated 

agriculture. The standards establish the maximum 

levels of EC and SAR that may be discharged into 

the rivers and streams throughout the basin without 

harming plants and soils. These standards have been 

approved by the U.S. EPA. As such, all Clean Water 

Act (CWA) permits issued in Montana must contain 

provisions that limit EC and SAR, so that the water 

quality standards will be met. In addition, all CWA 

permits issued in Wyoming authorizing discharges 

into streams that flow north into Montana contain 

conditions to ensure that Montana’s water quality 

standards are not exceeded at the border. Note 

Montana’s EC and SAR standards are currently being 

challenged in both Montana and federal courts.

The MDEQ water quality standards for EC and SAR 

are listed in Table 3-6.
CHAPTER 4

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4-86

In March 2006, the Montana BER amended its 

regulations implementing Montana's nondegradation 

policy in terms of EC and SAR. The State's 

nondegradation policy is part of the State's water 

quality standards program; therefore, any changes to 

regulations implementing the policy must be 

approved by EPA. Although the amended 

nondegradation regulations became effective under 

state law on May 19, 2006, they will not be enforced 

until approved by EPA.

Once approved, the new nondegradation 

requirements will apply to any proposal that would 

result in a new or increased discharge of EC and SAR 

into "high quality" waters of the State. State waters 

are considered high quality if the quality of those 

waters is better than that required by the water quality 

standards. Since MDEQ determines whether a water 

body is high quality on a parameter-by-parameter 

basis, a water body will be considered high quality in 

terms of EC and SAR, if the ambient quality of the 

stream is better than the water quality standards 

established for those parameters. A waterbody will 

not be considered high quality if the water is listed on 

the State's § 303(d) list as impaired because it does 

not meet the water quality standards for EC and SAR 

Under Montana's nondegradation law, any change in 

the existing quality of high quality waters is 

prohibited unless an authorization to degrade is 

obtained from MDEQ, or the change is deemed 

"nonsignificant" under rules adopted by the Montana 

BER. Under the newly amended regulation, any 

change in the existing quality of a high quality stream 

is deemed "significant" when the ambient quality of 

the stream is 40 percent of the standard or above.

Since all of the high quality streams within the 

Powder River Basin have ambient water quality that 

exceeds 40 percent of the standard for EC, any new 

proposal to discharge into those waters may require 

an authorization to degrade from MDEQ. 

In May 2002, the Northern Cheyenne Tribe adopted 

numerical water quality standards for SAR and EC 

applicable to waters within the Reservation. Although 

these tribal standards do not have Clean Water Act 

regulatory status until approved by the EPA, the 

adopted numerical standards do set out the tribe’s 

considered determination of the water quality needed 

to protect irrigated agriculture on the Reservation 

(Northern Cheyenne Tribe 2002). Standards for 

surface water quality proposed by the Northern 

Cheyenne Tribe are summarized in Table 3-24. 

The Montana BER standards adopted by the MDEQ 

on April 25, 2003 have been used in the analysis. It 

should also be noted that a non-degradation criterion 

exists for flow on high quality waters. This flow 

criterion requires individual discharge permits do not 

cause a 10 percent increase or decrease in the 7Q10 

flow or a 15 percent increase or decrease in mean 

monthly flow (Administrative Rules of Montana 

[ARM] 17.30.715.1.a). The non-degradation rules 

also state MDEQ may determine the change resulting 

from an activity is “significant” based on cumulative 

impacts despite it meeting the “nonsignificant” 

criteria for individual permits (ARM 17.30.715.2.a). 

It has been suggested a 40 percent increase in 

minimum mean monthly flow may be an appropriate 

level at which this cumulative significance threshold 

is met for flow; however this evaluation will be made 

based on the specific conditions which exist when 

each Montana Pollutant Discharge Elimination 

System (MPDES) permit is requested. Forty percent 

of minimum mean monthly flow will be used as a 

comparison analysis threshold for alternatives A-E 

and as a limiting factor for Montana discharges under 

alternatives F-H.

More recently, the Montana BER modified these 

standards by designating EC and SAR as “harmful” 

parameters. Harmful parameters are regulated under 

the non-degradation rules, which do not allow a 

discharge to increase a harmful parameter if ambient 

water quality is greater than 40 percent of the 

standard (see Hydrology Appendix for further 

details). If implemented, the effect of this rule would 

be that CBNG discharges to surface waters will need 

to be treated to ambient water quality standards since 

ambient EC and SAR values are greater than 40

percent of the standards in these watersheds. This 

modification of the EC and SAR standards has not 

been approved by EPA, so it does not have CWA

standing and is not enforceable upstream into 

Wyoming. The Wyoming Governor’s office has 

openly opposed this change. As such, it is assumed 

that CBNG development in Montana would have to 

be in compliance with these rules and treat all 

discharges to ambient water quality, but Wyoming 

development will not. If EPA approves these 

changes, the non-degradation rules would apply to 

Wyoming as well and impacts would be less than 

calculated. Forty percent of the EC and SAR values 

have been added as criteria for Alternatives A-E and

are incorporated into the analysis of Alternatives FH.

The Ayers and Westcot EC/SAR relationship is used 

to determine the effect of irrigation waters on the 

infiltration capacity of soils. This relationship 

recognizes that as salinity increases the potential 

impacts of SAR decrease. This relationship is not 

unbounded, however, because of the potential impact 

of rainfall on sodic soils. Rainfall can cause SAR

problems in surface soil because of the differential
CHAPTER 4

Hydrological Resources

4-87

way in which EC and SAR respond to a rain event 

(significant lowering of the EC and little change in 

the SAR). This rain-on-sodic-soil problem is 

addressed in a number of the standards proposals (see 

Hydrology Appendix) through adoption of an 

absolute maximum SAR (i.e., the standard “caps” the 

Ayers and Westcot EC/SAR relationship). It will be 

important to be mindful of an upper bound on the 

Ayers and Westcot relationship in reviewing the 

conclusions reached in the alternatives analyses in 

this document. This may help explain situations 

where the most restrictive proposed limit (MRPL) (or 

perhaps, the least [LRPL]) shows a potential effect, 

where the Ayers and Westcot diagram indicates no 

reduction in infiltration. This relationship is used as 

criteria against which the results of the surface water 

quality are compared.

Another factor to consider in applying these SAR and 

EC values is the significant distinction between the 

modeling approach applied to the analysis of 

alternatives and the approach that eventually will be 

used in calculating discharge limits for future, 

specific CBNG projects: 

• The modeling approach used in this document 

begins with an assumed water management 

method for all the reasonably foreseeable CBNG 

development in Montana and Wyoming and, 

applying a series of assumptions (see discussion

below), predicts a resultant instream cumulative 

water quality. Predicted water quality modeling 

output is then displayed against the full range of 

proposed SAR and EC limits and other criteria.

• The water quality-based approach that is actually 

used to calculate future Montana Pollutant 

Discharge Elimination System (MPDES) 

permitting requirements will begin with 

appropriate and specific instream water quality 

standards. Through the total maximum daily load 

(TMDL) process, those standards will be 

translated into discharge limits for specific 

CBNG projects. 

The standards serve as the regulatory basis for 

controlling CBNG discharges and the water qualitybased permitting approach that implements these 

standards is different from the predictive modeling 

approach used in this EIS. 

The water quality-based approach begins with a 

desired instream water quality and, using that as the 

target, calculates the CBNG discharge limits needed 

to ensure the desired instream water quality is 

achieved. The TMDL process identifies capacity for 

a waterbody to assimilate substances (maximum 

load). That capacity then has to be allocated among 

the appropriate governmental entities along that 

waterbody. It should be noted that, where a tribe is 

one of the appropriate governmental entities, EPA 

has a trust responsibility to ensure a fair and 

meaningful portion of the available assimilative 

capacity is reserved for that tribe. 

The spreadsheet model used in the analysis of 

impacts for the EIS employs a steady state mass 

balance approach to estimate concentrations of EC 

and SAR after stream water and CBNG discharged 

water are mixed. The steady state mass balance 

approach is commonly used by the EPA in predicting 

possible effects of point source discharges on 

receiving waters. Input parameters to the spreadsheet 

model were developed from analysis of reasonably 

conservative assumptions, as well as measures of 

central tendency (typical or mean values). 

The Surface Water Quality Analysis Technical 

Report (SWQATR) lists the input parameters and 

indicates whether conservative or mid-range values 

were used in the impact analysis model. The resultant 

spreadsheet model is considered to provide a 

conservative, yet reasonable estimate of the impacts 

of CBNG development on surface water quality in 

the Powder River Basin. The SWQATR also 

discusses the problems of manipulating sample SAR 

values (BLM 2003e). It should be noted this model is 

meant to be used to compare alternatives, not to 

predict precise resultant water quality.

Assumptions

CBNG development has the potential to impact 

surface water, surface aquifers and coal seam aquifers 

that hold the groundwater resources in the planning 

and CBNG emphasis area. The following 

assumptions form the framework for analyzing the 

impacts:

• Under the expanded development RFD, the 

maximum volume of CBNG water production 

and discharge is predicted to occur in year six for 

alternatives B-E. All surface water impacts are 

calculated using this maximum CBNG discharge 

volume.

• Under the phased development alternatives (F, G

and H), peak water production occurs at a 

different time for each watershed. Surface water 

impacts are calculated using the peak for each 

watershed.

• All modeling results shown in this EIS are for 

the minimum mean monthly stream discharges. 

7Q10 discharges are also included in the 

SWQATR analysis.
CHAPTER 4

Hydrological Resources

4-88

• SAR and EC were calculated using a simple 

flow-weighted mass balance equation. This 

assumption is strictly correct for EC however it 

results in an overestimation of SAR. This results 

in a conservative model of impacts due to CBNG 

discharges.

• To facilitate analysis, a range of water quality 

criteria was assumed based on the proposals 

before the Montana Board of Environmental 

Quality. This analysis has been supplemented by 

incorporation of the current Montana BER

approved standards for EC and SAR.

A complete listing of all model assumptions may be 

found in the SWQATR.

Impacts From Management 

Common to All Alternatives

Tongue River Railroad 

Construction of this railroad would be in accordance 

with all state and federal rules and regulations and

hydrological impacts are expected to be short-lived 

and minor. The act of construction in the vicinity of 

the Tongue River riparian zone will increase the local 

effects of soil erosion. This soil erosion is expected to 

deliver increased suspended sediment load to the 

Tongue and its tributaries. Localized erosion and 

runoff could cause locally increased streamflow in 

the river tributary and alter stream geometry. 

Mitigating measures and best management practices 

are expected to be required in the EIS for the TRR in 

order to minimize erosion and control runoff 

velocity. These impacts are anticipated to be of low 

intensity and of short duration. Sediment yields will 

return to natural levels once vegetation is 

reestablished. 

Conventional Oil and Gas Production

Conventional oil and gas production can produce 

large volumes of water that could impact surface and 

groundwater resources because of the quality of the 

produced water. Since 1953, the MBOGC has 

regulated the use and disposal of water produced in 

association with the production of oil and natural gas 

to mitigate the potential for impacts to the 

environment. 

The use of surface impoundments is controlled by 

BLM and the state. BLM permits water disposal pits 

(surface impoundments) on federal leases. The 

permitted surface impoundments are those designed 

primarily for evaporation. Any impoundments 

constructed in the state, including those involving 

federal land or minerals, would require approval from 

the MBOGC. Further, the MDEQ permits any pointsource discharges to surface waters (e.g., streams), 

including those that could result from surface 

impoundments. 

Conventional oil and gas is typically produced from 

depths below usable aquifers and below coal seams. 

Regulations require the isolation of oil and gas 

producing zones from other reservoirs containing 

possible hydrocarbons or from aquifers that contain 

usable water. Underground Injection Control (UIC) 

regulations also require safeguards to isolate injection

zones from other zones that contain hydrocarbons 

and from aquifers that contain usable or potentially 

usable quality water (i.e., groundwater containing 

less than 10,000 mg/l of total dissolved solids). 

Produced water that has a total dissolved solids 

(TDS) concentration of less than 15,000 mg/l, can be 

discharged to permitted surface impoundments. As a 

result of the existing regulations, the impact on 

surface water and groundwater resources from 

conventional oil and gas production is minimal.

CBNG Groundwater Drawdown and 

Water Mitigation Agreements

Drawdown from CBNG could cause wells and 

springs which obtain their water from the developed 

coal seams to have reduced yields. The drawdown of 

Powder River Basin coal seam aquifers as a result of 

CBNG production has been modeled several times. 

The Montana Bureau of Mines and Geology has 

performed two studies using Montana field 

parameters—a two-dimensional model (Wheaton and 

Metesh 2001) and a three-dimensional model 

(Wheaton and Metesh 2002). In addition, threedimensional modeling has been carried out using 

parameters from the Wyoming portion of the Powder 

River Basin (BLM 1999b).

The maximum lateral extent of drawdown within coal 

seam aquifers has been estimated by several methods. 

Monitoring around dewatered coal mines in the 

Wyoming portion of the Powder River Basin 

indicates five feet of drawdown extends from 2 to 14 

miles from mined areas after 15 years of mining 

(BLM 1999b). Three dimensional (3D) groundwater 

modeling conducted in conjunction with the 

WYODAK EIS (BLM 1999b) predicted five feet of 

drawdown at distances from 10 to 22 miles from the 

edge of production. Two dimensional (2D) 

groundwater modeling, which should represent the 

maximum limit of drawdown due to vertical leakage 

being ignored, was conducted in conjunction with 

this EIS. This 2D modeling indicated that five feet of 
CHAPTER 4

Hydrological Resources

4-89

drawdown within the Powder River Basin may 

extend up to 11 miles from the edge of CBNG 

production (Wheaton and Metesh 2001). 3D 

groundwater modeling of the East Fork of Hanging 

Woman Creek was also conducted in conjunction 

with this EIS. This model indicates the maximum 

extent of the five-foot drawdown contour extends up 

to seven miles from the edge of production (Wheaton 

and Metesh 2002). Based upon this information, the 

five-foot drawdown contour that would likely result 

from CBNG development, would extend from 7 to 11 

miles from the pumped area. The range of estimates 

however extends from 2 to 22 miles from the pumped 

area. 

These differences between results are not unexpected 

and serve to emphasize the site-specific nature of the 

geology in the Powder River Basin. As the hydrology 

is fundamentally linked to the geology, it will be 

critical to manage drawdown-related impacts in an 

adaptive manner, using site-specific data gathered 

through monitoring. Management alternatives may 

include re-supply of water to individuals who have 

springs or wells affected by drawdown (as required 

by Montana Code Annotated [MCA] 82-11-175), 

modification of production plans to limit drawdown 

impacts to springs where such springs have been 

determined to be culturally significant or critical to 

wildlife, or the installation of a hydrologic barrier 

that will limit the lateral extent of drawdown.

A hydraulic barrier would most likely take the form 

of a line or system of injection wells. These wells 

would inject water into the coal aquifer being 

developed to limit the lateral extent of groundwater 

drawdown and prevent that drainage of methane and 

groundwater resources. It should be emphasized the 

installation of a hydraulic barrier is just one of many 

methods that may be employed to prevent drainage. 

The feasibility and necessity of installing such a 

barrier will be addressed on a case-by-case basis. The 

water injected by a hydraulic barrier system would 

most likely be obtained from nearby CBNG 

production wells completed in the same aquifer as the 

injection wells. Class V permits for injection of 

produced water with less than 3, 000 mg/l TDS 

would generally need to be obtained from EPA 

Region VIII for such a project. Other permit 

requirements may apply depending on the quality of 

the injected water and quality of the water in the 

target coal seam. 

The uncertainty associated with modeling a five-foot 

drawdown contour is not insignificant since output of 

this nature is very sensitive to slight changes in the 

input parameters used for the model. Five feet of 

drawdown would not, in most cases, impact the 

usefulness of a well. Since a 20-foot drawdown 

contour can be modeled with a much higher degree of 

certainty and it is a more realistic parameter for 

evaluation of impacts, the 20-foot drawdown contour 

is used in this analysis to represent the extent of the 

drawdown which results from CBNG development. 

Based upon the 3D model prepared in conjunction 

with this EIS, the 20-foot contour can be expected to 

extend four to five miles from the edge of CBNG 

production.

As discussed in Chapter 3, monitoring since the 

completion of the statewide EIS indicates that “After 

six years of CBM production, drawdown of up to 20 

feet has been measured in the coal seams at a typical 

distance of roughly one mile and a maximum 

distance of one and a half miles outside the 

production areas. These distances are similar to, but 

somewhat less than predicted in the Montana CBM 

environmental impact statement.” (Wheaton et al. 

2006). 

Aquifers other than the produced coal seams, such as 

alluvium or sandstone bedrock aquifers, are less 

vulnerable to drawdown from CBNG production due 

to low vertical hydrologic conductivity in the Tongue 

River member of the Fort Union Formation. This will 

limit the vertical movement of groundwater 

(Wheaton and Metesh 2002, Wheaton and Donato 

2004). As discussed in Chapter 3, CBNG drawdown 

has not been observed in units other than the 

developed coal seams. Groundwater in units below 

the Tongue River Member of the Fort Union 

Formation would not be affected by CBNG 

development since it is underlain by the Lebo Shale, 

which is an effective aquitard.

Impacts to wells and springs which derive their water 

from regional flow within the produced coal seams 

and are located within the drawdown area would take 

the form of decreased discharge (yield). Few springs 

in this area obtain their water from regional flow 

through coal seams (Wheaton and Donato 2004). 

Most springs are located at the base of clinker ridges

and are fed by local flow systems. These locally-fed 

springs are not expected to be impacted by coal seam 

aquifer drawdown. Wells are anticipated to have 

decreased yields as a result of drawdown; however it 

is not anticipated they would go dry since the coal 

would continue to be saturated. For example, a 

typical PRB coal seam well with an initial head 200 

feet above the top of the coal could be pumped at a 

rate of approximately 25 gpm for six hours. If the 

head were decreased by 20 feet the rate achievable 

for six hours would drop to approximately 22.5 gpm

and if the head were dropped to five feet above the 

top of the coal the rate would drop to approximately 
CHAPTER 4

Hydrological Resources

4-90

2.3 gpm. The five feet above the top of the coal is 

comparable to conditions anticipated within CBNG 

fields while the 20-foot drawdown contour may 

extend four to five miles from the edge of CBNG 

fields (Wheaton and Metesh, 2002).

Although production of CBNG water enhances cleat 

within the coal seams, it would not propagate vertical 

fracturing into the adjacent shale confining units.

Recovery of the coal seam aquifers after production 

ends is a slow process involving recharge from 

undrained areas of the aquifer, infiltration of 

precipitation from the surface in areas where the coal 

aquifers outcrop and the slow process of infiltration 

from aquifers above and below the produced coal 

seams (this is expected to take the longest time 

because of the confined nature of these units).

Modelers assisting the Wyoming BLM determined 

coal seams that have experienced substantial 

drawdown also experience recovery as a two-part 

process: 

“After CBNG development (and water removal) 

ends, within three to four years water levels in the 

coal aquifers are expected to partially recover to 

within 20 to 30 feet of pre-operational conditions. 

Complete water level recovery will be a long-term 

process, likely requiring hundreds of years for the 

removed groundwater to be replaced through the 

infiltration of precipitation” (BLM 2000b). 

A similar recovery process is expected to occur in the 

Montana area of CBNG interest with most of the 

recovery happening in a short time but full coal seam 

aquifer recovery requiring hundreds of years. The 3D 

computer modeling conducted in conjunction with 

the statewide EIS estimates recovery schedules for 

methane-productive coal seams, nonproductive coal 

seams and surface aquifers in Montana. For 

productive coals within CBNG fields, the aquifers are 

expected to recover at least 70 percent of their 

hydrostatic pressure within five to 12 years. Outside

the field, productive coals should regain 90 percent of 

their pressure within three to five years. 

Nonproductive coals are predicted to regain 80 

percent of their pressure within five years. Surface 

aquifers that are projected to lose only six feet of 

pressure, would regain 50 percent of that pressure in 

less than 10 years (Wheaton and Metesh 2002). 

Precise local groundwater recovery differs depending 

on site-specific conditions. 

Water mitigation agreements are required in Montana 

under MCA 82-11-175, which was enacted by the 

Montana legislature in 2003. MCA 82-11-175 

requires CBNG operators offer a reasonable 

mitigation agreement to each person who holds an 

appropriation right or a permit to appropriate ground 

water and for which the point of diversion is within 

one mile of the coal bed methane well; or one-half 

mile of a well or spring that is adversely affected by 

the CBNG well.

Mitigation agreements must address the reduction or 

loss of water resources and must provide for prompt 

supplementation or replacement of water from any

natural spring or water well adversely affected by the 

coal bed methane well. 

MCA 82-11-175 applies to all

As such, the impacts due to ground water drawdown 

are mitigated by existing state requirements. It should 

wells and springs, not 

just those which derive their water from the 

developed coal seams and requires “...prompt 

supplementation or replacement of water from any 

natural spring or water well adversely affected by the 

CBNG project...” Adversely affected could include 

decreased yields, decreased water pressure, increase 

or sudden appearance of methane, or a change in 

water quality. Although the terms of water mitigation

agreements are to be “under such conditions as the 

parties mutually agree upon” the replacement of 

water required by these agreements is anticipated to 

take the form of reconfiguring existing wells, redrilling wells, or drilling new wells. These measures 

would be effective for replacing water sources since 

drawdown from CBNG activity is anticipated to 

primarily affect the produced coal seams and to only 

minimally affect other aquifers (such as sandstones) 

within the Tongue River Member of the Fort Union 

Formation. Any lost or diminished water sources or 

adversely affected groundwater would be anticipated 

to be replaced with a permanent source before the 

termination of the agreement. It is recognized that 

additional costs (power, moving irrigation piping, 

etc.) may be associated with the reconfiguration, 

redrilling, or replacement of impaired water wells

and those additional costs are typically paid for by 

the operator as outlined in the agreements. 

Furthermore, if a replacement well were required, a 

Replacement Well Water Right might be issued by 

DNRC, which would retain the priority date of the 

original well. An example water mitigation 

agreement is included in the Hydrology Appendix.

The owners of water sources are also protected from 

impacts from CBNG through the Coal Bed Methane 

Protection Act (MCA 76-15-9). This act provides for 

the establishment of the Coal Bed Methane 

Protection Account which can only be used to 

compensate landowners and water right holders for 

damages attributable to coal bed methane 

development. The text of MCA 76-15-9 is included 

in the Hydrology Appendix.
CHAPTER 4

Hydrological Resources

4-91

be noted drawdown itself is not eliminated; however 

affected parties have multiple means by which to be 

made whole. 

Impacts from Management Specific 

to Each Alternative

Impacts on Hydrological Resources under the 

management alternatives are summarized in 

Chapter 2, Table 2-3, Comparison Summary of 

Impacts. The impacts are discussed in detail for the 

major watersheds in the following sections.

Alternative A—No Action (Existing CBNG 

Management) 

Alternative A consists of the existing (2003) CBNG 

management scenario, with the addition of the 

forecasted future development of CBNG resources in 

the Wyoming portion of the Powder River Basin that 

occurs upstream of Montana. The Wyoming BLM 

has adopted Wyoming’s Alternative 2A for CBNG 

water management (BLM 2003d).

Under Montana’s Alternative A, only those 

producing wells that currently exist in the CX Ranch 

field will produce CBNG and water in Montana. 

Other CBNG exploration wells could be drilled on 

state and private minerals, but would not be allowed 

to produce gas or water. Rosebud Creek, the Bighorn 

River and Mizpah Creek would not receive any 

CBNG produced water under this alternative, as they 

would not be affected by Wyoming’s production. 

However, an analysis of their flow volumes and 

water chemistries are included for comparison to 

other alternatives. The Tongue River, Powder River

and Little Powder River watersheds could have 

impacts from CBNG development due to Wyoming 

production. 

Exploration

CBNG exploration activities on state, private, or 

BLM-administered mineral estates would result in 

only slight effects on groundwater and would not 

affect surface waters. Exploration wells would be 

tested but not commercially produced. Testing of 

CBNG exploration wells involves pumping the wells 

for several weeks; however, the volume of coal seam 

aquifer groundwater removed is moderate and is not 

expected to impact nearby water wells or springs. 

Recovered produced water and drilling wastes would 

be contained in impoundments or tanks and would be 

disposed of in accordance with regulations for 

conventional oil and gas wastes. 

Production

CBNG water production would continue to be 

allowed within the CX Ranch CBNG field, but at a 

level approximately 20 percent above current 

conditions; this would constitute a total of 250 

producing wells. An increase in soil erosion resulting 

from the construction of additional well pads and 

lease roads could occur, adding to the suspended 

sediment load of area surface waters.

The 250 producing CBNG wells at the CX Ranch 

field would also affect groundwater resources within 

the producing coal seam aquifers. Production at this 

level would result in increases to groundwater 

drawdown levels within the three coal seam aquifers 

being produced. Groundwater drawdown within the 

coal seams currently extends approximately one mile 

beyond the edge of CBNG production at the CX 

Ranch field (Wheaton et al. 2006). Increasing the size 

of the field by approximately 20 percent would add to 

the drawdown.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 

Water released to unlined surface impoundments may 

infiltrate into shallow aquifers, causing measured 

impacts to the groundwater. The introduction of this 

water into the aquifer may improve or degrade the 

usability of these waters, depending on site specific 

conditions. In general, it would be anticipated that 

over the short term (<5 years), as soluble salts 

(calcium-magnesium (Ca-Mg) sulfates) are dissolved 

from the flow path, the infiltration of this water will 

cause an increase in EC and a decrease in SAR

within the immediate vicinity of the impoundment. 

Over the long term (>5 years), after soluble salts are 

flushed from the system, the continued infiltration of 

this water would cause a decrease in EC and an 

increase in SAR. These impacts will be localized; 

however the precise geographic extent will depend on 

site specific conditions.

Surface Water Analysis

Tongue River

The Tongue River has its headwaters in the Bighorn 

Mountains to the south. This river could receive 

CBNG impacts from current and future development 

in both the Wyoming and Montana portions of the 
CHAPTER 4

Hydrological Resources

4-92

TABLE 4-33

EFFECTS ON SURFACE WATERS OF THE TONGUE RIVER UNDER ALTERNATIVE A

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity 

(Min. Mean Monthly) 

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Tongue River at 

Stateline Near Decker 3 1,000 5 1,500 178 0.86 731 183 1.93 773

Tongue River Near 

Birney Day School 3 1,000 5 1,500 183 1.09 863 190 2.52 912

Tongue River at 

Brandenburg Bridge 

Near Ashland, 

Montana

3 1,000 5 1,500 207 1.36 1,016 214 2.5 1,058

Powder River Basin. The detailed input data, 

calculation of impacts and summary of impacts from 

Alternatives can be reviewed in the SWQATR. 

Table 4-33 displays the impacts for the three stream 

stations analyzed along the Tongue River in 

Montana. It is assumed that approximately 15 percent 

of the water discharged into impoundments in the

Wyoming portion of the Tongue River watershed

would reach the Tongue River. In addition, other 

impacts to the Tongue River under Alternative A 

could result from the approximately 250 CBNG wells 

in the CX Ranch field. For this analysis, the CX 

Ranch discharge was split between the Decker station 

and the Birney station. 

During the minimum mean monthly flow, these 

impacts increase the flow volume and EC value in the 

stream by only a few percentage points, but increase 

the SAR value in the river water by up to 133 percent 

(1.4 units). The resultant mixed stream water and 

CBNG water can be compared to the following 

surface water criteria: 

• Northern Cheyenne Standards: Surface water 

alteration forecasted under Alternative A would 

be at or below the tribe’s proposed limits during 

the irrigation season (April through October) but 

would exceed the proposed standard for SAR 

during the non-irrigating season by up to 0.52 

SAR.

• Ayers and Westcot: The SWQATR displays the 

SAR versus EC plots for the Tongue River. 

These plots show that at no time would water 

cause infiltration impacts to soils under irrigation 

under Alternative A.

• MDEQ Irrigation Season Standards (Mt-Irr): 

These standards are set at a SAR of 3.0 and an 

EC of 1000 micro-Siemens per centimeter 

(μS/cm) for the Tongue River. The forecast 

surface water quality under Alternative A during 

minimum mean monthly flows is below these 

standards for all stations and below these EC 

standards for all stations except for the station at 

Brandenburg Bridge. Existing conditions at 

Brandenburg Bridge during minimum mean 

monthly flows are also in excess of this standard.

The 40 percent non-degradation analysis 

threshold for EC (400 μS/cm) is exceeded by 

existing conditions and the resulting surface 

water quality would increase this exceedance. 

The 40 percent non-degradation analysis 

threshold for SAR (1.2) is exceeded by existing 

conditions at the Brandenburg station and the 

resulting surface water quality would cause it to 

be exceeded at all stations.

• MDEQ Non-Irrigation Season Standards (MtNon): These standards are set at a SAR of 5.0 

and an EC of 1500 μS/cm for the Tongue River. 

The forecasted surface water quality under 

Alternative A during minimum mean monthly 

flows is below these SAR and EC standards for 

all stations. The 40 percent non-degradation 

analysis threshold for EC (600 the resulting 

surface water quality would increase this 

exceedance. The 40 percent non-degradation 

analysis threshold for SAR (2) is greater than 

existing conditions and the resulting surface 

water quality would cause it to be exceeded at 

the Birney Day School and Brandenburg 

stations.

• The 40-percent increase of minimum mean 

monthly flow analysis threshold (40 percent
CHAPTER 4

Hydrological Resources

4-93

MMM): This analysis threshold is not exceeded 

for any station.

Under Alternative A the surface water quality in the 

Tongue River would be slightly altered by CBNG 

development in Wyoming and the untreated 

discharge occurring in Montana under an existing 

permit. The numerical standards, which were 

developed to protect beneficial uses, are not exceeded 

except for EC at the Brandenburg station. The EC at 

the Brandenburg station also exceeds this standard 

under existing conditions. Therefore, it is not 

anticipated beneficial uses will be altered. 

Discharges of CBNG water would only slightly 

increase surface water flow in the Tongue River, 

causing negligible changes to physical stream 

conditions, even during historically low-flow periods. 

Powder River

The Powder River has its headwaters in the 

Wyoming portion of the Powder River Basin and as 

such would receive CBNG water from development 

in Wyoming. As no Montana CBNG wells are 

assumed to discharge into the Powder River under 

Alternative A, all forecasted alterations would be due 

to CBNG development in Wyoming. The analysis 

conducted at the Locate, Montana station includes all 

CBNG discharges into the Powder, Little Powder and

Mizpah, cumulatively. Table 4-34 summarizes these

impacts. During MMM flows the Powder River is 

expected to be affected by Wyoming CBNG 

development, resulting in an appreciable alteration of 

surface water chemistry. Only Wyoming CBNG 

development would affect the river. Flow volumes 

are forecasted to increase by approximately 54 

percent SAR would be increased by approximately 

130 percent and EC would be increased by 3 to 4 

percent. The resultant mixed stream water quality can 

be compared to the available surface water criteria:

• Ayers and Westcot: The SWQATR includes 

SAR vs. EC plots to document that the resultant 

water quality during minimum mean monthly 

flows will not cause infiltration impacts to soils 

under irrigation.

• MT-Irr: These standards are set at a SAR of 5.0 

and an EC of 2,000 μS/cm for the Powder River. 

The forecasted surface water quality under 

Alternative A during minimum mean monthly 

flows is above the SAR and EC standards. 

Existing conditions also exceed this EC standard. 

As such, permitted discharges in Wyoming may 

have to be managed differently than assumed 

under Wyoming's Alternative 2A in order to be 

in compliance with the Montana standard. The 

40 percent non-degradation analysis threshold 

for EC (800 μS/cm) and SAR (2) are exceeded 

by existing conditions and the resulting surface 

water quality would increase these exceedances. 

• MT-Non: These standards are set at a SAR of 6.5 

and an EC of 2,500 μS/cm for the Powder River. 

The forecasted surface water quality under 

Alternative A during minimum mean monthly 

flows is above this SAR standard and below the 

EC standard. As such, permitted discharges in 

Wyoming may need to be managed differently 

than assumed under Wyoming's Alternative 2A 

in order to be in compliance with the Montana 

standard. The 40 percent non-degradation 

analysis threshold for EC (1000 μS/cm) and 

SAR (2.6) are exceeded by existing conditions

and the resulting surface water quality would 

increase these exceedances. 

• 40 percent MMM: This analysis threshold would 

be 203 cfs at Moorhead and 200 cfs at Locate. 

This is exceeded for both stations by discharges 

in Wyoming.

TABLE 4-34 

EFFECTS ON SURFACE WATERS IN THE POWDER RIVER UNDER ALTERNATIVE A

MDEQ Surface 

Water Quality 

Standards Irrigation 

Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water 

Quality and Quantity

(Min, Mean Monthly)

Resulting Stream Water 

Quality and Quantity (Min, 

Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Powder River at 

Moorhead 5 2000 6.5 2500 145 4.65 2154 224 10.7 2230

Powder River at 

Locate 5 2000 6.5 2500 143 4.61 2287 236 11.36 2320
CHAPTER 4

Hydrological Resources

4-94

Under Alternative A the surface water quality in the 

Powder River would be noticeably altered by CBNG 

development in Wyoming. Flows would also 

substantially increase, potentially leading to 

noticeable changes to physical stream conditions. The 

numerical standards for EC and SAR, which were 

developed to protect beneficial uses, are exceeded at 

all stations. The EC standards are also exceeded by 

existing and historic ambient conditions. As such, 

permitted discharges in Wyoming may need to be 

managed differently than assumed under Wyoming's 

Alternative 2A in order to be in compliance with the 

Montana standards.

The Little Powder River 

The Little Powder River has its headwaters in the 

Wyoming portion of the Powder River Basin and as 

such it is expected to receive CBNG water from 

development in that state. All analyses for this stream 

are conducted at the Weston, Wyoming, station, near 

the stateline. At this station, no effects are possible 

from Montana CBNG under any alternative; however 

Montana CBNG discharges are addressed by the 

cumulative analysis of the Powder River at Locate.

Table 4-35 illustrates the effects expected on the 

Little Powder River from CBNG development under 

Alternative A. 

Only Wyoming CBNG discharges affect the river 

under this alternative. During minimum mean 

monthly flows, this development will cause the flow 

to increase by 515 percent, the EC to decrease by 51 

percent and the SAR to increase by 50 percent. The 

resultant mixed stream water and CBNG water can 

be compared to the following surface water criteria:

• Ayers and Westcot: The SWQATR plots suggest 

that during the mean monthly flows for 2 months 

of the year (November and December) the mixed 

water may cause infiltration impacts to soils 

under irrigation. The elevated SAR may reduce 

soil permeability, thereby reducing the rate of 

water infiltration. 

• MT-Irr: These standards are set at a SAR of 5.0 

and an EC of 2,000 μS/cm for the Little Powder 

River. The forecasted surface water quality under 

Alternative A during minimum mean monthly 

flows is well above the SAR standard and below 

the EC standard. Existing conditions exceed the 

SAR and EC standards. As such, permitted 

discharges in Wyoming may need to be managed 

differently than assumed under Wyoming's 

Alternative 2A in order to be in compliance with 

the Montana standard. The 40 percent nondegradation analysis threshold for EC (800 

μS/cm) is exceeded by existing conditions and

the resulting surface water quality would 

decrease this exceedance. The 40 percent nondegradation analysis threshold for SAR (2) is 

exceeded by existing conditions and the resulting 

surface water quality would increase this 

exceedance. 

• MT-Non: These standards are set at a SAR of 6.5 

and an EC of 2,500 μS/cm for the Little Powder 

River. The forecasted surface water quality under 

Alternative A during minimum mean monthly 

flows is well above this SAR standard and below 

the EC standard. Existing conditions exceed the 

SAR and EC standards. As such, permitted 

discharges in Wyoming may need to be managed 

differently than assumed under Wyoming's 

Alternative 2A in order to be in compliance with 

the Montana standard. The 40 percent nondegradation analysis threshold for EC (1000 

μS/cm) is exceeded by existing conditions and

the resulting surface water quality would 

decrease this exceedance. The 40 percent nondegradation analysis threshold for SAR (2.6) is 

exceeded by existing conditions and the resulting 

surface water quality would increase this 

exceedance.

TABLE 4-35

EFFECTS ON SURFACE WATERS OF THE LITTLE POWDER RIVER UNDER ALTERNATIVE A

MDEQ Surface Water 

Quality Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Little Powder above 

Dry Creek 5 2000 6.5 2500 3 6.9 3300 16 10.4 1606
CHAPTER 4

Hydrological Resources

4-95

• 40 percent MMM: This analysis threshold would 

be 4.6 cfs at Weston. This is exceeded by 

forecast Wyoming discharges, with the result 

being 16 cfs.

Under Alternative A the surface water quality in the 

Little Powder River would be noticeably altered by 

CBNG development in Wyoming. The numerical 

standards for EC and SAR were developed to protect 

beneficial uses. The numerical EC standard is 

exceeded by existing conditions, but would not be 

exceeded by forecasted conditions. The numerical 

SAR standard is exceeded by existing conditions and

this exceedance would be increased by forecasted

conditions. As such, permitted discharges in 

Wyoming may need to be managed differently than 

assumed under Wyoming's Alternative 2A in order to 

be in compliance with the Montana standards. 

Wyoming discharges of CBNG water would increase 

surface water flow into the Little Powder River by 

more than six times, causing major changes to stream 

conditions including increased flow, channel erosion

and sedimentation during historically low-flow 

periods.

Mizpah Creek

The Mizpah contains low quality water that has 

limited irrigation use, but can be used for stock 

watering and wildlife. This watershed is not expected 

to be affected by CBNG activity under Alternative A, 

as shown on Table 4-36. This stream water can be 

compared to the following surface water criteria:

• Ayers and Westcot: Except for 3 months out of 

the year, the average existing water exceeds 

irrigation water quality limits set by Ayers and 

Westcot.

• MT-Irr: These standards are set at a SAR of 3.0 

and an EC of 500 μS/cm for tributaries of the 

Powder River. Existing surface water quality 

during minimum mean monthly flows is above 

these SAR and EC standards. The 40 percent 

non-degradation analysis thresholds for EC (200 

μS/cm) and SAR (1.2) are also exceeded by 

existing conditions. 

• MT-Non: These standards are set at a SAR of 5.0 

and an EC of 500 μS/cm for tributaries of the 

Powder River. Existing surface water quality 

during minimum mean monthly flows is above 

these SAR and EC standards. The 40 percent 

non-degradation analysis thresholds for EC (200 

μS/cm) and SAR (2) are also exceeded by 

existing conditions.

• 40 percent MMM: This analysis threshold would 

be 0.36 cfs at Mizpah. No discharge is forecast in 

this watershed under this alternative.

All current uses of these waters would be maintained 

under Alternative A.

Bighorn and Little Bighorn Rivers

These rivers carry high quality water from the 

Bighorn Mountains north into Montana. No CBNG 

wells in Wyoming or Montana are expected to impact

these rivers under Alternative A. Stream water 

quality and flow volume are expected to remain 

unchanged. As shown on Table 4-37, the following 

expected results can be compared to the following 

surface water quality criteria: 

• Ayers and Westcot: The monthly average 

existing water quality at all three stations is 

within irrigation water quality limits set by 

Ayers and Westcot.

TABLE 4-36

EFFECTS ON SURFACE WATER OF MIZPAH CREEK UNDER ALTERNATIVE A

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Mizpah Creek at 

Mizpah 3 500 5 500 0.26 16.6 3503 0.26 16.6 3503
CHAPTER 4

Hydrological Resources

4-96

TABLE 4-37

EFFECTS ON SURFACE WATERS OF THE LITTLE BIGHORN AND BIGHORN RIVERS 

UNDER ALTERNATIVE A

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Little Bighorn River 

at Wyola N/A N/A N/A N/A 110 0.53 548 110 0.53 548

Little Bighorn at 

Hardin N/A N/A N/A N/A 123 0.99 768 123 0.99 768

Bighorn River at 

Bighorn N/A N/A N/A N/A 1523 2.08 952 1523 2.08 962

• EC and SAR standards have not been developed 

for these waters. 

• 40 percent MMM: This analysis threshold would 

be 154 cubic feet per second (cfs) at Wyola, 172 

cfs at Hardin and 2132 cfs at Bighorn. No 

discharge is forecast in this watershed under this 

alternative.

All current uses of these waters would be maintained 

under Alternative A.

Rosebud Creek

This creek drains part of the Powder River Basin in 

Montana. No CBNG water would be discharged into 

this creek; therefore, stream water quality and flow is 

unchanged as shown on Table 4-38. These expected 

results can be compared to the following surface 

water quality criteria:

• Ayers and Westcot: The monthly average 

existing water quality at both stations is within 

irrigation water quality limits set by Ayers and 

Westcot.

• MT-Irr: These standards are set at a SAR of 3.0 

and an EC of 1,000 μS/cm for Rosebud Creek. 

Existing surface water quality during minimum

mean monthly flows is above the SAR standard 

at the Rosebud station and above the EC 

standard for both stations. The 40 percent nondegradation analysis threshold for EC (400 

μS/cm) is exceeded at both stations. The 40 

percent non-degradation analysis threshold for 

SAR (1.2) is exceeded by existing conditions at 

the Rosebud station.

• MT-Non: These standards are set at a SAR of 5.0 

and an EC of 1500 μS/cm for Rosebud Creek. 

Existing surface water quality during minimum 

mean monthly flows is below the SAR standard 

for both stations and above the EC standards for 

the Rosebud station. The 40 percent nondegradation analysis threshold for EC (600 

μS/cm) is exceeded at both stations. The 40

percent non-degradation analysis threshold for 

SAR (2) is exceeded by existing conditions at the 

Rosebud station. 

• 40 percent MMM: This analysis threshold would 

be 2.5 cfs at Kirby and 11.8 cfs at Rosebud. No 

discharge is forecast in this watershed under this 

alternative.

All current uses of these waters would be maintained 

under Alternative A.

Yellowstone River

The Yellowstone River drains all of the Montana 

watersheds in the Powder River Basin. As such it 

provides an analysis of the cumulative effects 

forecasted from CBNG development in Montana and 

Wyoming in the Bighorn, Rosebud, Tongue, Powder 

and Yellowstone watersheds. 

Only the station at Sidney is expected to receive 

CBNG related effects under Alternative A. These 

effects are in the form of discharge from CX Ranch 

in Montana and Wyoming CBNG wells. After 

mixing, the flow of the Yellowstone would be 

increased by 1 percent, the SAR would be increased 

by 13 percent and the EC would be increased by 1 

percent. The resultant mixed stream water, shown on 

Table 4-39, can be compared to the following surface 

water criteria:
CHAPTER 4

Hydrological Resources

4-97

TABLE 4-38

EFFECTS ON SURFACE WATER OF ROSEBUD CREEK UNDER ALTERNATIVE A

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Rosebud Creek at 

Kirby 3 1000 5 1500 1.78 0.77 1016 1.78 0.77 1016

Rosebud Creek at 

Rosebud 3 1000 5 1500 8.42 4.84 1780 8.42 4.84 1780

TABLE 4-39

EFFECTS ON SURFACE WATER OF THE YELLOWSTONE RIVER UNDER ALTERNATIVE A

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface Water 

Quality Standards 

Non-Irrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Yellowstone at 

Forsyth, Montana N/A N/A N/A N/A 5820 1.99 745 5820 1.99 745

Yellowstone at 

Sidney, Montana N/A N/A N/A N/A 5764 2 870 5805 2.26 881

• Ayers and Westcot: The SWQATR’s plots 

predict that the mixed water would not cause 

infiltration impacts to soils under irrigation under 

Alternative A.

• EC and SAR standards have not been developed 

for these waters.

• 40 percent MMM: This analysis threshold would 

be 8148 cfs at Forsyth and 8070 cfs at Sidney.

This analysis threshold is not exceeded for either 

station.

Under Alternative A the surface water quality in the 

Yellowstone River would be slightly altered by 

CBNG development in Wyoming and the untreated 

discharge occurring in Montana under an existing 

permit. The numerical standards, which were 

developed to protect beneficial uses, are not 

exceeded. Therefore, it is not anticipated that

beneficial uses will be altered. 

Discharges of CBNG water would only slightly 

increase surface water flow in the Yellowstone River, 

causing negligible changes to physical stream 

conditions, even during historically low-flow periods. 

Abandonment

Abandoned well pads would be restored to their 

original condition with the only effect being the 

short-term increase in suspended sediments in area 

surface waters resulting from the increased erosion of 

disturbed soil. CBNG wells that are not produced 

would be abandoned in accordance with existing 

regulations and with procedures for the abandonment 

of oil and gas wells to protect groundwater resources, 

or converted to monitoring wells as deemed 

necessary. 

Crow Reservation

The Crow Reservation can expect few effects from 

CBNG development within Montana under this 

alternative. Continued development is expected in the 

CX Ranch field near Decker. Groundwater 

drawdown is expected to extend approximately 4-5 

miles from the CX Ranch development. This 
CHAPTER 4

Hydrological Resources

4-98

drawdown could impact water wells and springs that 

receive water from these coal seams on tribal land. 

Scattered CBNG exploration drilling and testing 

would have only slight effects on reservation coal 

seam aquifers.

CBNG development in Montana and Wyoming could 

drain groundwater and methane from coal seams 

under the Reservation.

If Wyoming CBNG operators are able to discharge 

CBNG water into either the Little Bighorn or 

Bighorn watersheds, there could be effects to surface 

waters on the Reservation. However, there are 

currently no proposals to develop CBNG in these 

watersheds in Wyoming. 

Northern Cheyenne Reservation

The Northern Cheyenne Reservation can expect 

effects to surface water by CBNG development 

outside the reservation under this alternative. The CX 

Ranch has a permit to discharge CBNG water to the 

Tongue River and this would continue under this 

alternative. Effects to surface water are described in 

detail in the surface water section of this alternative

and in the SWQATR. Groundwater drawdown is 

expected to extend approximately four to five miles 

from the CX Ranch development. This groundwater 

drawdown effect would not reach the Northern 

Cheyenne Reservation.

CBNG development in Wyoming is not expected to 

affect groundwater under the Reservation. Permitted 

outfalls, accidental releases and unintended 

infiltration under storage ponds could contribute 

some effect to the Tongue River from Wyoming.

Conclusion

Montana-based CBNG development, conventional oil 

and gas development, the Tongue River Railroad and

surface coal mining would have the potential for 

effects to surface water and coal seam aquifer 

groundwater resources in Montana. Few CBNG wells 

would be drilled and impacts would be limited in 

both magnitude and geographic extent. CBNG 

development at the CX Ranch field could expand, 

although surface discharge volume to the Tongue 

River would be controlled by an existing permit. 

Groundwater impacts to methane-productive coal 

seam aquifers from the CX Ranch are expected to 

extend 4-5 miles from the edge of development. 

Scattered CBNG exploration and testing would have 

a slight effect on static water levels in coal seam 

aquifers, but would not affect surface waters.

Coal seams that are the targets of surface coal mining 

operations typically contain groundwater. As a result 

of the presence of this water, coal mine operators 

must remove this water as it collects in the bottom of 

the pits in order to mine the coal. Map 4-2 shows coal 

mines in the Planning Area. These mines cover 

approximately 50,000 acres where coal seam aquifers 

have been impacted either by the removal, partial 

depletion, or total depletion of groundwater. In the 

mining areas around Colstrip and Decker, coal seam 

aquifers have been drawn down by as much as 75 

feet near the coal mines, with a radius of impact of up 

to 4 miles from the mines (Wheaton and Metesh 

2001). The discharge of groundwater pumped from 

mine pits would also affect surface water depending 

on the quality of groundwater near the mine and the 

quantity of groundwater discharged. In instances 

where the mines do not discharge because all of the 

recovered groundwater is used, there would be no 

direct impacts to surface water quality. Much of the 

groundwater pumped from the mine pits would be 

stored and used to control dust on roads, truck and

train car loading areas and the mine face. 

Following the release of the Wyodak EIS (BLM 

1999b), the RFD for the Wyoming portion of the 

Powder River Basin was reassessed and a new RFD 

was issued (BLM 2001a). This more recent study 

indicates that the total number of CBNG wells in the 

Wyoming portion of the Powder River Basin may 

approach 50,000 (BLM 2001a). An EIS using this 

level of development has been completed for 

Wyoming.

Groundwater resources in Montana’s coal seam 

aquifers could be affected by CBNG production in 

Wyoming. CBNG-producing wells in northern 

Wyoming would cause a drawdown of coal aquifers 

on adjacent land, with groundwater drawdown 

possibly extending northward into Montana. If 

CBNG fields were located in Wyoming adjacent to 

the border with Montana, it can be expected that 

groundwater levels within coal seam aquifers would 

be drawn down 20 feet at 4-5 miles into Montana. 

Drawdown impacts of this magnitude would result in 

impacts on private lands, the Crow Reservation, 

state-owned lands and federal lands controlled by 

BLM. Cumulative groundwater impacts to coal seam 

aquifers would be largest near CX Ranch and close to 

the Wyoming border.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 
CHAPTER 4

Hydrological Resources

4-99
CHAPTER 4

Hydrological Resources

4-100

The numerical surface water quality limits adopted 

by the Montana Board of Environmental Review are 

enforceable upstream under the CWA. As such, both 

Montana and Wyoming may need to curtail the 

surface discharge of CBNG water. If Wyoming 

CBNG development reaches expected levels, 

Montana watersheds could be impacted to the point 

where water quality standards could prohibit CBNG

discharge. For this impact analysis, it is assumed that 

the Wyoming Alternative 2A will be implemented; 

however in some watersheds development in 

Wyoming may need to proceed differently than 

assumed under Wyoming's Alternative 2A in order to 

ensure that Montana's surface water quality standards 

are not exceeded.

The Montana BER’s rule change which made EC and 

SAR harmful parameters has not been approved by 

the EPA and so it does not have CWA standing; 

however if this change is approved by EPA further 

modification of water management practices in 

Wyoming would be needed.

Surface water discharge permits that limit the 

quantity and quality of discharged CBNG water are 

required in Montana and Wyoming. This permitting 

process, which incorporates the numerical and nondegradation standards, would mitigate the impacts 

from Wyoming CBNG production and from 

expanded CX Ranch production since permitted 

discharges must be in compliance with the CWA. 

Beneficial reuse of CBNG water is expected to 

continue in the vicinity of the CX Ranch field as well 

as other areas near the Wyoming-Montana border. 

The increased flow of water in some streams may 

allow increased utilization of the mixed water if 

quality is appropriate.

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Alternative B consists of full-scale development of 

CBNG with water produced from CBNG exploration 

wells stored in tanks or impoundments and all water 

produced from CBNG production wells to be injected 

into approved subsurface zones other than the coal 

seam from which it was produced. No CBNG water

would be discharged to the surface. The number of 

producing CBNG wells being analyzed is 16,500, 

which is the RFD number minus those wells not 

covered by this EIS (tribal and USFS wells) minus 10 

percent dry holes. The estimated 16,500 CBNG wells 

would draw down groundwater levels within coal 

seam aquifers in areas adjacent to CBNG 

development, affecting water wells and springs that 

draw water from the productive coal seams. The 

construction of well pads and lease roads would 

result in surface disturbances that would increase the 

potential for soil erosion, consequently increasing 

short-term surface water suspended sediment loads. 

Exploration

Full-scale CBNG exploration would require water 

generated from the testing of CBNG exploration 

wells be stored in tanks or impoundments on state 

and federal lands. Construction permits would require 

measures to reduce leakage from impoundments. The 

estimated 2,000 dry CBNG exploration wells would 

result in the short-term disturbance of approximately 

2,000 acres of land at the well sites. These disturbed 

acres would be vulnerable to soil erosion that would 

cause run-off water impacted by suspended sediment. 

BMPs to curtail soil erosion such as water bars across 

lease roads, relieving and mulching cut-banks and

restoration of the surface would serve to mitigate 

erosion related effects to surface water resources. 

Short-term testing of CBNG exploration wells would 

not substantially affect static water levels of area coal 

seam aquifers

Production

CBNG production is expected to be concentrated in 

the Powder River Basin, but could also develop 

locally in other portions of the state. This full-scale 

level of CBNG development would result in the 

potential for impacts to surface water resources from 

increased soil erosion and the accidental releases of 

produced water. Full-scale development of 

16,500 producing CBNG wells would disturb an 

estimated 54,000 acres, which would increase the 

potential for soil erosion and the corresponding 

impact to surface water. However, the 

implementation of BMPs described in the preceding 

paragraph would reduce the potential for impacts 

from soil erosion. Because produced water would be 

disposed by injection into deep aquifers, surface 

water quality effects are predicted to be the same as 

Alternative A. 

The projected 16,500 production wells would 

generate an estimated average of 2.9 billion cubic 

feet of produced water per year over 20 years. CBNG 

water produced in Montana is expected to be similar

in chemistry to Wyoming CBNG water. The 

produced water would be expected to have a range of 

SAR values from 22 to 47 and EC values ranging 

from 2,077 to 3,042 μS/cm. 

Using the assumptions in the RFD and the 

extrapolated discharge trend line, it is calculated that 
CHAPTER 4

Hydrological Resources

4-101

the maximum annual volume of produced water 

would occur in year 6 of the plan. During year six, 

7,750 wells would be producing with an average rate 

of 6.2 gpm per well, for a total volume of 3.4 bcf of 

produced water in that year. 

Water management options under this alternative 

would consist of the injection of CBNG-produced 

waters into approved subsurface zones. No discharge 

of CBNG waters would be allowed. Some of the 

produced water would be temporarily stored in tanks 

or impoundments prior to injection. These facilities 

could fail, causing localized impacts to surface water 

and shallow groundwater. The implementation of 

BMPs concerning the location and construction of 

these impoundments would mitigate the potential for 

impacts to surface water from the stored produced 

waters. Berms around tank batteries would reduce the 

potential for impacts from leaks and catastrophic 

failures. 

Localized impacts from impoundments would be 

similar to those described under Alternative A.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. During the 20-year 

planning period for CBNG production, groundwater 

levels within coal seam aquifers could be drawn 

down over large, contiguous areas of the state. For 

example, the Upper Tongue watershed covers 

590,000 acres and could hold 5,800 CBNG wells as 

projected in the RFD. Over the life of the project 

approximately five percent of the groundwater in the 

coal seam aquifers could be lost to CBNG production 

in this watershed. Following methodology detailed in 

the Water Resources Technical Report (ALL 2001b), 

potential CBNG-producing wells per watershed and 

potential coal seam aquifer groundwater production 

estimates for 20 years of production for each of the 

watersheds have been calculated and are listed in 

Table 4-40. 

In those portions of Montana where CBNG is 

developed outside of the Powder River Basin, CBNG 

production is not expected to be as concentrated and 

hydrological impacts would be less. Limited CBNG 

production in these areas would result in the localized 

drawdown of groundwater levels within coal seam 

aquifers. 

An estimated 2.9 bcf of produced water would be 

injected into deep aquifers annually throughout the 

state. This process would not affect coal seam 

aquifers. The injection of CBNG-produced water has 

not been conducted in Montana, but is commonplace 

for waters produced from conventional oil and gas 

activities. In the year 2000, the state of Montana 

averaged 847 injection/disposal wells that disposed 

of 0.6 billion cubic feet of water every year (average 

injection of 128,000 bbl of water per well per year). 

Injection of CBNG water under this alternative is 

estimated to increase the number of injection wells to 

nearly 3,000. These new CBNG injection wells 

would have an average injection rate of 265,000 

barrels of water per well per year. This water would 

either be injected into shallow aquifers with 

compatible water quality or into deep aquifers, whose 

water is not fit for use. Given the effectiveness of 

current injection regulations, the increase in injected 

volume resulting from CBNG production is 

anticipated to have only a minimal effect on surface 

water or groundwater resources. 

The major limitation to injection will be the presence 

of suitable injection zones. As discussed in Chapter 

3, within particular study areas it has been shown 

suitable shallow sand injection targets underlie 

approximately 9 percent of the area (Wheaton and 

Reddish 2005). Injection zones need to be able to 

transmit water away from the injection well and store 

it. 

Thick channel sandstones and undeveloped coals 

within the Fort Union Formation are expected to have 

sufficient transmissivity, would maintain the water 

quality and would allow the water to be retrieved in 

the future. Injection into these shallow zones may be 

limited due to the injection zones already being 

saturated and pressurized and sandstones being 

lenticular in nature. These shallow zones may also 

contain water wells, monitoring wells and boreholes 

which would provide conduits to the surface for the 

injected water. Because these zones are shallow the 

fracture pressure of the zone is low and will not allow 

much pressure to be applied while injecting, this 

would limit the amount of water that could be forced 

into the zone. If the fracture pressure of the zone was 

exceeded the injected water may be forced into other 

zones and to the surface through water wells or 

monitoring wells. These factors may cause these 

zones to be limited in the volume of water that they 

may accept.
CHAPTER 4

Hydrological Resources

4-102

TABLE 4-40

GROUNDWATER DEPLETION BY CBNG DEVELOPMENT IN THE MONTANA POWDER RIVER

BASIN

Watershed Potential CBNG Producing Wells

Potential Produced CBNG Water in 20 years

(billion cubic feet)

Little Big Horn 675 2.5

Little Powder 200 0.7

Lower Bighorn 800 2.8

Lower Tongue 3,450 12.0

Lower Yellowstone 1,700 6.0

Middle Powder 2,100 7.4

Mizpah 125 0.5

Rosebud 3,600 12.6

Upper Tongue 3,850 13.5

Total 16,500 58.0

Note: Calculated maximum potential coal seam aquifer groundwater production by watershed (billion cubic feet) after 20 years of 

CBNG production. Details on the method used to calculate these numbers can be obtained from the Water Resources Technical 

Report (ALL 2001b).

Deeper injection zones, such as the Madison 

Formation, are expected to have sufficient 

transmissivity and storativity to accept the water; 

however the saline nature of the existing water in 

these zones would degrade the injected water to the 

point where it could not be retrieved and used. The 

depth to these zones would also prohibit the recovery 

of the water resource. Injection into deep zones may 

also be prohibitively expensive, resulting in less 

CBNG development than predicted in the RFD.

Abandonment

When the estimated 16,500 production wells are 

abandoned throughout the life of the resource in the 

Planning Area, 33,000 acres of soil would be 

disturbed for a short time period. This disturbed soil 

would be vulnerable to erosion and the resulting 

suspended material could be washed into adjacent 

surface waters unless mitigating measures are 

employed. The implementation of BMPs would 

mitigate the potential for impacts to surface water 

resources resulting from soil erosion until 

groundcover and original site conditions are restored. 

CBNG wells that are not produced, or have reached 

the end of their productive life would be abandoned 

in accordance with existing regulations and

procedures for the abandonment of oil and gas wells 

to protect groundwater resources, or converted to 

monitoring wells, as deemed necessary.

Crow Reservation

Surface water effects on Crow Tribal Lands under 

Alternative B would include those impacts noted in 

Alternative A. Additional impacts from suspended 

sediment due to soil erosion and runoff from the 

disturbed acreage are expected near the Crow 

Reservation from the development of private land 

within the exterior boundaries of the Crow 

Reservation, or from development of CBNG on tribal

Lands. 

Groundwater impacts would include those detailed in 

Alternative A as well as additional impacts from 

nearby wells. The tribe can expect 20 feet of 

drawdown in coal seam aquifers from CBNG wells to

extend 4 to 5 miles from CBNG wells near the 

Reservation boundaries towards the later part of the 

20 year production period. The drawdown in 

producing coal seams may be as high as 10 feet for 

wells within one to two miles of the boundary during 

the early stages of production. This drawdown would 

affect water wells and springs within the reservation 

that derive water from productive coal seam aquifers. 

In addition, because of the large presence of private

land within the exterior boundaries of the Crow 

Reservation, CBNG development on those nonreservation lands could also affect surface water and 

groundwater in a manner consistent with other areas 

of the Powder River Basin. The development of 

CBNG on private lands within the reservation 

boundary could result in increased suspended 

sediment loads from surface disturbances in the 
CHAPTER 4

Hydrological Resources

4-103

Bighorn, Little Bighorn, Rosebud and Squirrel Creek 

watersheds. 

Northern Cheyenne

Surface water effects on Northern Cheyenne Tribal 

Lands under Alternative B would include those 

impacts noted in Alternative A. Additional effects are 

expected from suspended sediment as a result of soil 

erosion and runoff from the area upstream of the 

Northern Cheyenne Reservation. Increased sediment 

loads would affect both the Tongue River and 

Rosebud Creek watersheds resulting from the surface 

disturbances associated with CBNG development. 

Groundwater drawdown effects on the reservation 

would be similar to impacts in other areas of the 

Powder River Basin. The tribe can expect up to 20 

feet of drawdown to extend four to five miles in the 

produced coal seam aquifers from CBNG 

development near the reservation boundary. This 

drawdown would affect water wells and springs 

within the reservation that derive water from the 

produced coal seam aquifers. 

Conclusion

Impacts on surface water and groundwater as a result 

of Wyoming CBNG development, coal mines and the

Tongue River Railroad would be same as discussed 

under Alternative A. Impacts on surface water would 

include those impacts listed under Alternative A plus 

the impact of suspended sediment generated by soil 

erosion taking place near CBNG development. There 

would be no substantial increase in surface water 

flow beyond what was described for Alternative A 

because all CBNG produced water in Montana would 

be managed by injection. 

CBNG production in Montana under Alternative B 

would result in the withdrawal of approximately 

five percent of the groundwater resources contained

within the producing coal seams and approximately 

0.1 percent to 0.2 percent of the total recoverable 

groundwater resources that underlie Montana’s 

portion of the Powder River Basin. This withdrawal 

estimate was derived from Specific Storage values 

(3x10-4 to 9 x 10-4) from modeling (Wheaton and 

Metesh 2002) assuming an average of 70 feet of coal 

and a drawdown of 200 feet needed to release 

economic volumes of methane. Water wells 

completed in the developed coals near CBNG fields 

could experience drops in static water levels. 

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 

Alternative C—Emphasize CBNG 

Development

Alternative C consists of the direct discharge of 

CBNG-produced waters to the land surface. Impacts 

to water resources resulting from this alternative 

would consist of coal seam drawdown-related effects 

similar to Alternative B and effects due to the large 

volume of CBNG water being discharged to the 

ground and allowed to flow into drainages and water 

bodies. 

Discharge to the ground would cause increased soil 

erosion between the discharge point and the nearest 

drainage. There would be a corresponding increase in 

the suspended sediment load in surface waters 

adjacent to CBNG development. As CBNG water 

flows along drainages, infiltration of the water would 

occur, resulting in rising shallow groundwater 

elevations and shifts in the chemistry of the shallow 

groundwater. These shifts in groundwater chemistry

may improve or degrade the usability of the 

groundwater, depending on site-specific conditions. 

In general it would be anticipated that over the short 

term, as soluble salts (Ca-Mg sulfates) are dissolved 

from the flow path, the introduction of this water

would cause an increase in EC and a decrease in 

SAR. Over the long term, when the soluble salts are 

flushed from the system, the continued infiltration of 

this water may cause a decrease in EC and an 

increase in SAR since the CBNG water typically has 

an EC less than the alluvial groundwater and an SAR 

greater than the alluvial groundwater. The infiltrated 

water would flow downgradient in the alluvial 

aquifers until a perennial waterway is reached. In 

gaining streams, this groundwater would be 

discharged to surface waters. Within the PRB most 

streams are losing streams, with alluvial groundwater 

levels below the base of the streams which results in 

surface water infiltrating into the groundwater.

CBNG water that does not infiltrate or evaporate en 

route would reach perennial waterways as point 

discharges. The addition of CBNG water to drainages 

and surface water bodies, through both point and 

diffuse discharges, would result in increased flow 

volumes and changes in water chemistry. These 

changes would, in turn, lead to loss of soil structure, 

increased erosion rates and increased suspended 

sediment loads. The chemistry of the surface waters 

would also potentially impact some uses by humans 

and wildlife.
CHAPTER 4

Hydrological Resources

4-104

Exploration

Impacts would be similar to those described in the 

Alternative B discussion. The moderate volume of 

water generated by the testing of CBNG exploration

wells would be stored in tanks or impoundments to 

be discharged under the appropriate permits. 

Impacts from exploration would be similar to those 

discussed under alternative B.

Production

Alternative C assumes 80 percent of the volume of 

CBNG water produced would be discharged directly 

to the land surface adjacent to the wellhead. Impacts 

to water resources would consist of those effects of 

coal seam drawdown described in the impacts 

common to all alternatives section, soil erosion and 

the increase in suspended sediments in area rivers 

and streams, changes in the elevation of groundwater 

in alluvial aquifers, changes in alluvial aquifer water 

chemistry and changes in the chemistry of perennial 

water bodies. The discharge at the CBNG wellhead 

would result in the erosion of soils, creating gullies 

that would connect to natural runoff areas where the 

water would join natural drainage. These natural 

drainages or ephemeral portions of the water-course 

would also be impacted by increased erosion and 

would likely become more nearly perennial as a 

result of receiving CBNG discharge water. Before the 

CBNG water reaches surface water, some portion 

would evaporate or infiltrate into the soil. The portion 

lost would depend upon season of the year, 

permeability of the soil and the presence of a 

shallow, unconfined aquifer connected to surface 

water. 

In addition to direct surface discharge, produced 

water would also be placed into impoundments for 

use by livestock and wildlife. Impacts from 

impoundments would be similar to those described 

under Alternative A.

Impacts on groundwater under this alternative would 

be the same as in Alternative B, except that

discharged water could infiltrate into soils and 

underlying shallow alluvial aquifers. The produced 

water from the only Montana CBNG field (CX 

Ranch) has an SAR value in excess of the water 

contained in most shallow aquifers, including the 

alluvial aquifers (ALL 2001b). If infiltration of 

CBNG-produced water occurred, the water quality of 

the alluvium could be adversely impacted.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 

Surface Water Analysis

The following discussion concentrates on watersheds 

of the Powder River Basin, because the Powder River 

Basin is the most likely area for major CBNG activity 

that could impact surface water resources. 

Tongue River

The Tongue River could be impacted from current 

and future CBNG development in both the Wyoming 

and Montana portions of the Powder River Basin. 

The detailed input data, calculation of effects and a 

summary of impacts are presented in the SWQATR. 

Table 4-41 encapsulates the effects for three stream 

stations along the Tongue River in Montana for 

Alternative C.

These results show the combined effects for CBNG 

water discharged from RFD development for 

Wyoming and Montana. These discharges would 

result in a 10 to 27 percent increase in surface water 

EC, a 211 to 725 percent increase in surface water 

SAR and a 5 to 28 percent increase in flow. The 

resultant mixed stream water can be compared to the 

following surface water criteria: 

• Northern Cheyenne Proposed Standards: The 

resultant mixed water quality at the stateline 

station would exceed the proposed irrigation 

season limits for SAR during 5 months out of the 

year and the 7Q10; the 7Q10 flow would also 

exceed the EC limit. The resultant water quality 

is similarly above the non-irrigation season 

proposed limits.

• The resultant water quality at the Birney Day 

School station, near the southern boundary of the 

Reservation, would exceed the SAR limit for 

11 months of the year and would only exceed the 

EC limit during 7Q10 flows. The water quality 

near the northern end of the Reservation is seen 

at the Ashland station. The calculated impacts at 

Ashland demonstrate that the Northern Cheyenne 

proposed standards would be exceeded for SAR 

on all but one month while the EC limits would 

not be exceeded.
CHAPTER 4

Hydrological Resources

4-105

TABLE 4-41

EFFECTS ON SURFACE WATERS OF THE TONGUE RIVER UNDER ALTERNATIVE C

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water 

Quality and Quantity 

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Tongue River at 

Stateline near 

Decker

3 100 5 1500 178 0.86 731 187 2.68-

2.94 806-812

Tongue River Near 

Birney Day School 3 1000 5 1500 183 1.09 863 213 6.38-

7.43

1055-

1080

Tongue River at 

Brandenburg Bridge 

near Ashland, 

Montana

3 1000 5 1500 207 1.36 1016 265 9.51-

11.22

1278-

1319

• Ayers and Westcot: Impact analyses show that 

Tongue River water at Decker would not result 

in impacts to soil except during 7Q10 flow. The 

resultant water quality at the Birney Day School 

and Ashland stations would result in some 

impacts to soil during irrigation use. 

• MT-Irr: These standards are set at a SAR of 3.0 

and an EC of 1000 μS/cm for the Tongue River. 

The forecasted surface water quality under 

Alternative C during minimum mean monthly 

flows are below these standards for the Stateline 

station and above these standards for all other 

stations. As such, an authorization to degrade 

would be needed from the MDEQ for 

development to occur in this manner. 

• MT-Non: These standards are set at a SAR of 5.0 

and an EC of 1500 μS/cm for the Tongue River. 

The forecasted surface water quality under 

Alternative C during minimum mean monthly 

flows is below these standards for the Stateline 

station. EC values are below these standards for 

all stations. SAR values at the Birney Day 

School station and Brandenburg Bridge stations 

are in excess of these standards. As such, an 

authorization to degrade would be needed from 

the MDEQ for development to occur in this 

manner. The non-degradation analysis threshold

would also be exceeded.

• 40 percent MMM: This analysis threshold would 

be 249 cfs at Decker, 256 cfs at Birney Day 

School and 290 cfs at Brandenburg. This 

analysis threshold is not exceeded at any station.

The surface water quality of the Tongue River would 

be degraded, requiring management practice changes 

by downstream users during part or all of the year 

under Alternative C. This is a legal option, so long as 

CBNG producers were granted a permit to degrade 

surface waters by the MDEQ. Additional impact 

analyses are presented in the SWQATR.

Moderate increases in flow would also result under 

this alternative, which may result in slight changes to 

physical stream conditions. 

Powder River

The Powder River has its headwaters in the 

Wyoming portion of the Powder River Basin and as 

such would receive CBNG water from development 

in Wyoming and Montana. The detailed analysis and 

calculations for the data summarized in Table 4-42 

can be found in the SWQATR. Table 4-42 

summarizes the impacts for two stations along the 

Powder River for Alternative C during the minimum 

mean monthly flow. The analysis conducted at the 

Locate station includes all CBNG discharge in the 

Powder, Little Powder and Mizpah watersheds, 

cumulatively. 

The Powder River contains water that is naturally 

above some of the proposed limits. The Powder River 

is expected to be affected by Wyoming and Montana 

CBNG development under this alternative. The 

resultant water quality is altered by slight changes of 

1 percent to 3 percent for EC, but SAR increases by 

as much as 200 percent. The flow rate is expected to 

increase between 25 percent and 30 percent. The 

resultant mixed stream water and CBNG water can 

be compared to the following surface water criteria:
CHAPTER 4

Hydrological Resources

4-106

TABLE 4-42 

EFFECTS ON SURFACE WATERS IN THE POWDER RIVER UNDER ALTERNATIVE C

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water 

Quality and Quantity

(Min. Mean Monthly)

Resulting Stream Water

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Powder River at 

Moorhead 5 2000 6.5 2500 145 4.65 2154 231 11.08-

11.56

2226-

2253

Powder River at 

Locate 5 2000 6.5 2500 143 4.61 2287 250 11.97-

13.13

2323-

2361

• Ayers and Westcot: The SWQATR displays the 

SAR vs. EC plots that show that the only time 

the water quality at the Powder River stations 

would be likely to cause infiltration impacts to 

soils under irrigation is during 7Q10 flow.

• MT-Irr: These standards are set at a SAR of 5.0 

and an EC of 2,000 μS/cm for the Powder River. 

The forecasted surface water quality under 

Alternative C during minimum mean monthly 

flows is above the SAR and EC standards. 

Existing conditions also exceed this EC standard. 

As such an authorization to degrade would be 

needed from the MDEQ for development to 

occur in this manner. The non-degradation 

analysis threshold would also be exceeded.

• MT-Non: These standards are set at a SAR of 6.5 

and an EC of 2,500 μS/cm for the Powder River. 

The forecasted surface water quality under 

Alternative C during minimum mean monthly 

flows is above this SAR standard and below the 

EC standard. As such an authorization to degrade 

would be needed from the MDEQ for 

development to occur in this manner. The nondegradation analysis threshold would also be 

exceeded.

• 40 percent MMM: This analysis threshold would 

be 203 cfs at Moorhead and 200 cfs at Locate.

This analysis threshold would be exceeded at 

both stations.

The surface water quality in the Powder River is 

degraded under Alternative C. These effects would 

likely require management practice changes by 

downstream irrigators. This is a legal option, so long 

as CBNG producers were granted a permit to degrade 

surface waters by the MDEQ. Additional impact 

analyses are presented in the SWQATR.

Substantial increases in flow would also result under 

this alternative, which might result in noticeable 

changes to physical stream conditions. 

Little Powder River 

The effects to the Little Powder River station at 

Weston, Wyoming, would be the same as 

Alternative A since there are no Montana wells being 

discharged upstream of this station. The impacts from 

Montana wells downstream of this station are 

analyzed in the analysis for the Powder River at 

Locate station. 

Mizpah Creek

Mizpah Creek carries water into the Powder River in 

Montana. There are no CBNG wells in Wyoming that 

could affect this watershed. Under Alternative C 

effects to Mizpah Creek would result from the 

discharge of Montana CBNG produced water only. 

Table 4-43 summarizes predicted changes in surface 

water chemistry in Mizpah Creek just upstream from 

its junction with the Powder River. 

Although CBNG discharge would decrease surface 

water EC by 10 to 24 percent, the SAR would 

increase by 25 to 112 percent. The resultant mixed 

stream water can be compared to the available 

surface water criteria:
CHAPTER 4

Hydrological Resources

4-107

TABLE 4-43 

EFFECTS ON SURFACE WATERS IN THE MIZPAH CREEK UNDER ALTERNATIVE C

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Mizpah Creek at 

Mizpah 3 500 5 500 0.26 16.6 3503 0.99 20.43-

35.26 

2663-

3163

• Ayers and Westcot: The SWQATR displays the 

plots that show the mixed water quality at the 

Mizpah station would likely cause infiltration 

impacts to soils under irrigation during all flows 

except for one or two high flow months a year. 

Discharge of CBNG waters would cause further 

exceedance of these criteria.

• MT-Irr: These standards are set at a SAR of 3.0 

and an EC of 500 μS/cm for tributaries of the 

Powder River. The forecasted surface water 

quality under Alternative C during minimum 

mean monthly flows is well above these 

standards. As such an authorization to degrade 

would be needed from the MDEQ for 

development to occur in this manner. The nondegradation analysis threshold would also be 

exceeded.

• MT-Non: These standards are set at a SAR of 5.0 

and an EC of 500 μS/cm for tributaries of the 

Powder River. The forecasted surface water 

quality under Alternative C during minimum 

mean monthly flows is well above these SAR 

and EC standards. As such an authorization to 

degrade would be needed from the MDEQ for 

development to occur in this manner. The nondegradation analysis threshold would also be 

exceeded.

• 40 percent MMM: This analysis threshold would 

be 0.42 cfs. This analysis threshold would be 

exceeded under this alternative.

The surface water quality in Mizpah Creek is 

degraded under Alternative C. These effects would 

likely require management practice changes by 

downstream irrigators. This is a legal option, so long 

as CBNG producers were granted an authorization to 

degrade surface waters by the MDEQ. The 

Additional impact analyses are presented in the 

SWQATR.

Substantial increases in flow would also result under 

this alternative, which might result in noticeable 

changes to physical stream conditions. 

Bighorn and Little Bighorn Rivers

These rivers carry water from the Bighorn Mountains 

north from Wyoming into Montana. No CBNG wells 

in Wyoming are expected to affect these rivers. 

Under Alternative C, the effects to these rivers would 

be the result of discharge from Montana CBNG 

discharge only. Table 4-44 summarizes the effects for 

two stations along the Little Bighorn River and one 

on the Bighorn River, just upstream from its 

confluence with the Yellowstone River, for the 

minimum mean monthly flow.

The resultant water quality impacts for these rivers 

would include an increase in EC by approximately 

11 percent to 162 percent and an SAR increase of 

27 percent to 400 percent. Flows would increase by 

2 to 8 percent. The resultant mixed stream water can 

be compared to the following surface water criteria:

• Ayers and Westcot: The Technical Report 

displays the plots that show the mixed water 

quality at the Wyola and Hardin stations would 

be likely to cause infiltration impacts to soils 

under irrigation during several months of the 

year. The resultant water qualities represent a 

low EC to SAR relationship and thus the water 

would likely impact clayey soils if used for 

irrigation. Water quality at Bighorn would likely 

cause no infiltration impacts and be adequate to 

use for irrigation. 

• EC and SAR standards have not been developed 

for these waters. 
CHAPTER 4

Hydrological Resources

4-108

TABLE 4-44 

EFFECTS ON SURFACE WATERS OF THE BIGHORN AND LITTLE BIGHORN RIVERS

UNDER ALTERNATIVE C

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Little Bighorn River 

at Wyola N/A N/A N/A N/A 110 0.53 548 115 2.26-

2.64 623-632

Little Bighorn River 

at Hardin N/A N/A N/A N/A 123 0.99 768 133 3.94-

4.59 881-896

Bighorn River at

Bighorn N/A N/A N/A N/A 1523 2.08 952 1542 2.54-

2.64 968-970

• 40 percent MMM: This analysis threshold would 

be 154 cfs at Wyola, 172 cfs at Hardin and 2132 

cfs at Bighorn. This analysis threshold is not 

exceeded at any station.

The surface water quality in the Bighorn rivers in 

Montana would be degraded, resulting in minor 

management practice changes by downstream users 

for continued irrigation use. This is a legal option, so 

long as CBNG producers were granted a permit to 

degrade surface waters by the MDEQ. Additional 

impact analyses are presented in the SWQATR.

Moderate increases in flow would also result under 

this alternative, which may result in slight changes to 

physical stream conditions. 

Rosebud Creek

Rosebud Creek drains part of the area of the Powder 

River Basin in Montana. This creek begins on the 

Crow Reservation, flows through a portion of 

Montana, flows through the Northern Cheyenne 

Reservation, then through another portion of 

Montana prior to joining the Yellowstone River near 

Rosebud Montana. No CBNG wells in Wyoming 

could affect the Rosebud. The effects to this stream 

would be the result of CBNG discharges in Montana. 

Table 4-45 summarizes the predicted effects for two 

stations along Rosebud Creek in Montana for the 

minimum mean monthly flow.

These results show the effects of CBNG discharge on 

the flow and water quality of Rosebud Creek. 

Because there is so little water in the Creek naturally, 

flow increases by an order of magnitude with CBNG 

discharge and water quality is more representative of 

the CBNG discharged water than the existing stream 

water quality. The resultant mixed stream water and 

CBNG water can be compared to the available 

surface water criteria:

• Ayers and Westcot: The plots show that the 

mixed water quality at the Kirby and Rosebud 

stations would likely cause severe infiltration 

impacts to soils under irrigation during all 

months of the year under Alternative C.

TABLE 4-45 

EFFECTS ON SURFACE WATER OF ROSEBUD CREEK UNDER ALTERNATIVE C

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Rosebud Creek at 

Kirby 3 1000 5 1500 1.78 0.77 1016 22 35.62-

43.25

2110-

2293

Rosebud Creek at 

Rosebud 3 1000 5 1500 8.42 4.84 1780 49 32.85-

39.32

2133-

2298
CHAPTER 4

Hydrological Resources

4-109

• Northern Cheyenne Standards at Southern 

Boundary (Kirby): These standards are set a 

SAR of 2.0 and an EC of 1000 μS/cm. The 

forecasted surface water quality under 

Alternative C during minimum mean monthly 

flows would be well above these SAR and EC 

standards. If these standards are adopted by the 

EPA, CBNG operators would need to obtain 

authorizations to degrade from the Northern 

Cheyenne Tribe for development to occur in this 

manner.

• MT-Irr: These standards are set at a SAR of 3.0 

and an EC of 1,000 μS/cm for Rosebud Creek. 

The forecasted surface water quality under 

Alternative C during minimum mean monthly 

flows is well above these standards at both 

stations. As such an authorization to degrade 

would be needed from the MDEQ for 

development to occur in this manner. The nondegradation analysis threshold would also be 

exceeded.

• MT-Non: These standards are set at a SAR of 5.0 

and an EC of 1500 μS/cm for Rosebud Creek. 

The forecasted surface water quality under 

Alternative C during minimum mean monthly 

flows is well above the SAR and EC standards 

for both stations. As such an authorization to 

degrade would be needed from the MDEQ for 

development to occur in this manner. MDEQ has 

never approved an authorization to degrade. The 

non-degradation analysis threshold criteria

would also be exceeded.

• 40 percent MMM: This analysis threshold would 

be 2.5 cfs at Kirby and 11.8 cfs at Rosebud. This 

analysis threshold would be exceeded at both 

stations.

Under Alternative C, the surface water quality in 

Rosebud Creek in Montana would be degraded, 

resulting in severe curtailment of irrigation use of this 

water. This is a legal option, so long as CBNG

producers were granted a permit to degrade surface 

waters by the MDEQ. Additional impact analyses are 

presented in the SWQATR.

Substantial increases in flow would also result under 

this alternative, which might result in noticeable 

changes to physical stream conditions. Increased flow 

may contribute to already impaired stream 

conditions.

Yellowstone River

The waters of the Yellowstone River are the 

confluence of all the other watersheds that are 

expected to receive effects from CBNG development 

in Montana. The Forsyth station would be affected by 

CBNG discharges into the Bighorn and Little 

Bighorn watersheds. The Sidney station would be 

affected by all Montana CBNG development and that 

development in Wyoming that occurs in the Tongue, 

Powder and Little Powder watersheds. Table 4-46 

summarizes the impacts for two stations along the 

Yellowstone River in Montana for the minimum 

mean monthly flow for Alternative C.

Because of the significant volume of water available 

in the Yellowstone to dilute the CBNG production 

water in Montana and Wyoming, the resultant water 

quality shows only slight changes in both EC and 

SAR. The resultant mixed stream water and CBNG

water can be compared to the following surface water 

criteria:

• Ayers and Westcot: The plots show that the 

mixed water quality would not cause infiltration 

impacts to soils under irrigation at any time. 

Under Alternative C, the surface water quality in 

the Yellowstone River in Montana is slightly 

reduced; however, there should be no 

management practice changes required of 

downstream users for continued irrigation use of 

this water. The resultant water quality in the 

Yellowstone River is sufficient for irrigation 

even during the months with the lowest flows.

• EC and SAR standards have not been developed 

for these waters. 

• 40 percent MMM: This analysis threshold would 

be 8148 cfs at Forsyth and 8070 cfs at Sidney.

This analysis threshold is not exceeded at either 

station.

The surface water quality in the Yellowstone River 

would be noticeably degraded by discharges from 

Montana and Wyoming under Alternative C; 

however, beneficial uses would not be impacted. 

Additional impact analyses are presented in the 

SWQATR.

Moderate increases in flow would also result under 

this alternative, which may result in slight changes to 

physical stream conditions. 
CHAPTER 4

Hydrological Resources

4-110

TABLE 4-46

EFFECTS ON SURFACE WATERS OF THE YELLOWSTONE RIVER UNDER ALTERNATIVE C

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Lower YellowstoneSunday near Forsyth N/A N/A N/A N/A 5820 1.99 745 5850 2.18-

2.22 753-754

Lower YellowstoneSunday near Sidney N/A N/A N/A N/A 5764 2.00 870 5857 3.12-

3.31 912-917 

Abandonment

Effects on water resources caused by abandonment 

operations would be similar to impacts by produced 

water discharged to the surface. The two activities—

soil disturbance at abandonment and 20 years of 

surface discharge—would combine to increase the 

suspended sediment load within area surface water 

streams and rivers.

Crow Reservation

Effects on the Crow Reservation’s surface water 

would be in the form of increased flow volume and 

changes in water quality. Groundwater impacts 

would be the same as Alternative B. In addition, 

potential CBNG development on private land within 

the external boundaries of the reservation could cause 

more direct effects that would also be similar to those 

effects described for the CBNG emphasis area. 

Surface waters would be affected in terms of both 

quantity and quality based on the extent of discharge 

to the watersheds within the reservations boundary 

(Bighorn, Little Bighorn, Rosebud and Squirrel 

Creek watersheds). The effects on these surface 

waters would place additional impacts onto the 

tribe’s way of life by limiting the uses of effected 

waters.

Northern Cheyenne

Effects on the Northern Cheyenne Reservation are 

similar to effects projected for the CBNG emphasis 

area. Effects to surface water would include increases 

in flow volume and changes in various water quality 

parameters in the Tongue River and Rosebud Creek

watersheds. The effects to the Tongue River and 

Rosebud Creek watersheds from Wyoming and 

Montana CBNG development could affect existing 

uses of these waters within the reservation boundary. 

Groundwater effects would be the similar to 

Alternative B, with additional impacts resulting from 

the infiltration of produced water into shallow 

aquifers along the Tongue River and Rosebud Creek 

watersheds within the reservation boundary. 

The effects to these surface waters would limit the 

uses of affected waters. The changes to groundwater 

quality that result from infiltration would be sitespecific and depend on the quality of the alluvial 

aquifers. The tribe can expect drawdown of coal 

seam aquifers from CBNG production in the area 

surrounding the reservation for distances of 

approximately four to five miles. 

Conclusion

Effects on groundwater include those listed under 

Alternative B, as well as effects from infiltration of 

surface water into shallow aquifers from 

impoundments and drainages. 

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 

Surface water quality in some watersheds would be 

slightly to severely degraded, resulting in restricted 

downstream use of some waters. Surface water flows 

will be considerably increased in some watersheds, 

causing persistent riparian erosion, changes in 

watercourses and increased sedimentation. Surface 

water quality standards and non-degradation analysis 

thresholds for EC and SAR would be exceeded in 

most watersheds and beneficial uses would be 

impaired.
CHAPTER 4

Hydrological Resources

4-111

Area surface waters would be affected by an increase 

in suspended sediments contained in the discharged 

CBNG water. This increase in suspended sediment 

load would result from the increased erosion of soils

due to surficial disturbances, CBNG water runoff 

from the point of discharge to drainages and from the 

increased erosion of stream banks resulting from 

increased water volume and increased SAR (which 

causes clays to lose their cohesiveness and erode 

more easily). The increase in suspended sediment 

content of surface water could affect its beneficial 

uses. All of the watersheds in the CBNG emphasis 

area would be vulnerable to effects from an increase 

in suspended sediment. Discharge to ephemeral 

channels would cause deepening and widening of the 

channels.

Effects on Montana watersheds from Wyoming 

CBNG discharge, coal mines and the Tongue River

Railroad would be the same under this alternative as 

under Alternative A.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

An estimated 20 percent of produced water would be 

used for beneficial uses and the remaining 80 percent 

would be treated to pre-development surface water 

chemistry prior to discharge under a MPDES permit. 

Discharge would be accomplished by pipeline or 

constructed watercourse to the nearest body of water 

to eliminate soil erosion, the generation of suspended 

sediments and the infiltration of treated CBNG water. 

The treatment of CBNG-produced waters would 

eliminate or greatly reduce effects to surface water

quality. Treatment may increase the potential for 

beneficial uses of CBNG water.

The changes in surface water quality shown in 

Table 4-47 for Alternative D are due to the discharge 

of untreated CBNG water from Wyoming CBNG 

development. Changes in flow volume are due to 

treated and untreated discharges in both Montana and 

Wyoming. The effects originating from Wyoming 

would be the same as those detailed under 

Alternative A. Effects on surface water from 

Montana CBNG development are due to the increases

in baseflow. The stations analyzed would experience 

a 0.2 percent (Yellowstone at Forsyth) to 

1135 percent (Rosebud at Kirby) increase in flow 

under this alternative. These increases in water flow 

rates would be likely to cause changes in streambed 

geometry, flow regime, stream depth distribution, 

presence and condition of instream vegetation and

other physical factors associated with the stream and 

adjacent riparian zone.

Exploration

Any water generated by drilling and testing would be 

treated, with 80 percent of the treated water 

discharged via pipeline under a MPDES permit and 

20 percent used for beneficial purposes. Treatment 

would eliminate potential impacts to water quality. 

Water quantity impacts would be minor because of 

the moderate volume produced from the testing of 

CBNG exploration wells.

Production

Approximately 80 percent of CBNG-produced water 

would be treated and discharged under this 

alternative. Because the water is piped to the

receiving body of water, no conveyance losses are 

deducted. 

Impoundments may be used to store CBNG water 

prior to treatment. Impacts from impoundments would 

be similar to those described under Alternative A.

Peak total field discharge during year six would add 

about 0.7 percent to the total discharge of the 

Yellowstone. In detail, every watershed, except the 

Yellowstone and the Bighorn, experience at least a 10 

percent increase in flow in at least one portion of the 

watershed. Rosebud Creek, the Little Powder and

Mizpah Creek would experience the greatest 

percentage change in baseflow during year 6, with 

1,135 percent, 515 percent and 285 percent increases 

in baseflow respectively. These increases in flow 

volume would result in increased erosion in affected 

watersheds. 

These changes in flow are in excess of the 40 percent

MMM flow analysis threshold in the Rosebud and 

Powder River (including the Little Powder and 

Mizpah) watersheds. In the Rosebud watershed this 

exceedance would be caused by treated discharges in 

Montana. The exceedance in the Powder and Little 

Powder rivers would be due to discharges in both 

Montana and Wyoming. The exceedance in the 

Mizpah would be due to treated discharges in 

Montana. An increase in flow of this magnitude 

would likely be found to be significant under 

MDEQ’s non-degradation rules. As such, permits to 

degrade would likely be needed before discharge at 

this scale would be allowed. Additional impact 

analyses are presented in the SWQATR.
CHAPTER 4

Hydrological Resources

4-112

TABLE 4-47

SUMMARY OF SURFACE WATER PARAMETERS BEFORE AND AFTER MIXING1

UNTREATED CBNG DISCHARGE FROM WYOMING AND TREATED CBNG DISCHARGES FROM 

MONTANA UNDER ALTERNATIVE D

Station

Existing Stream Water Quality and Quantity 

(Min. Mean Monthly)

Resulting Stream Water Quality and Quantity

(Min. Mean Monthly)

Flow

(cfs) SAR EC

(μS/cm)

Flow

(cfs) SAR EC

(μS/cm)

Tongue River Stateline Near Decker 178 0.86 731 188 1.49 747

Tongue River Near Birney Day 

School

183 1.09 863 220 1.59 824

Tongue River at Brandenburg 

Bridge Near Ashland, Montana

207 1.36 1016 278 1.67 904

Little Bighorn River at Wyola 110 0.53 548 117 0.53 548

Little Bighorn River at Hardin 123 0.99 768 135 0.99 768

Bighorn River at Bighorn 1523 2.08 952 1547 2.08 952

Rosebud Creek at Kirby 1.78 0.77 1016 272 0.77 1016

Rosebud Creek at Rosebud 8.42 4.84 1780 592 4.84 1780 

Little Powder River Stateline Station 

Weston, WY (No Montana CBNG 

wells will impact this station)

2.6 6.94 3300 162 10.41 1606

Powder River at Moorhead 145 4.65 2154 2332 11.08 2226

Powder River at Locate 143 4.61 2287 2502 10.89 2268

Mizpah Creek at Mizpah 0.26 16.6 3503 1.172 16.6 3503

Yellowstone at Forsyth, Montana 5820 1.99 745 5870 1.99 745

Yellowstone at Sidney, Montana 5764 2 870 5866 2.23 870

1 Calculations of flow volume and water quality were conducted for low mean monthly stream flows and the maximum calculated levels of CBNG 

discharge (year 6 discharge). Change in minimum mean monthly flow is greater than 40 percent. 

2 Change in minimum mean monthly flow is greater than 40 percent.

Substantial increases in flow would also result under 

this alternative in some watersheds, which would 

result in noticeable changes to physical stream 

conditions.

Since discharge water would be treated, the water 

quality of the streams and therefore the beneficial 

uses of surface waters, would not be directly affected 

by Montana CBNG development.

The treatment of CBNG-produced waters could result 

in the generation of residues that would contain 

concentrated salts extracted from the CBNG water. 

This residuum would need to be analyzed on a caseby-case basis to determine its character and would 

need to be disposed of in an appropriate manner. 

Impacts on groundwater under this alternative would 

be the same as in Alternative B. As discussed under 

impacts common to all alternatives, drawdown from 

CBNG could cause wells and springs which obtain 

their water from the developed coal seams to have 

reduced yields. It is anticipated the requirements for 

water mitigation agreements under MCA-82-11-175

and the protections provided by MCA 75-15-9, will 

mitigate these drawdown-related impacts. 

Abandonment

Effects on water resources caused by abandonment 

operations would be similar to the effects identified 

under Alternative B. When the estimated 

16,500 CBNG production wells are abandoned over 

the 20-year life of the resource, 33,000 acres of soil 

would be disturbed for a short time period. This 

disturbed soil would be vulnerable to erosion and the 

resulting suspended material would be washed into 

adjacent surface waters unless mitigating measures 

are employed. The implementation of BMPs would 

control soil erosion until groundcover and original 

site conditions are restored. 
CHAPTER 4

Hydrological Resources

4-113

Crow Reservation Impacts 

Surface water impacts on Crow Tribal Lands under 

Alternative D are expected to include those impacts 

noted in Alternative B. Because the produced water 

would be treated prior to discharge, the reservation 

could expect impacts to surface water in the form of 

increased flow volume to the Bighorn, Little Bighorn, 

Rosebud and Squirrel Creek watersheds from 

development on private lands within the external 

boundary of the reservation. Groundwater effects 

would be similar to those detailed in Alternative B.

Northern Cheyenne Impacts

Surface water impacts on Northern Cheyenne Tribal 

Lands under Alternative D are expected to include 

those effects noted in Alternative B with the added 

effects from the treated surface discharge of 80 

percent of the produced water from all of the 

Montana CBNG wells forecast in the RFD in the 

Rosebud and Tongue River watersheds. Groundwater 

effects would include those detailed in Alternative B. 

Conclusion

Treatment and discharge of produced water from 

Montana would not affect surface water quality, but 

would affect river flow volumes. Flow volumes in 

some watersheds would change only slightly, but 

some watersheds would see large flow increases, 

especially during times of traditionally low flow. The 

effects of these changes could include bank erosion, 

riparian area alteration and loss of indigenous habitat. 

Effects to surface water flow would be similar to but 

slightly greater than for Alternative C, due to lower 

conveyance loss. Effects on Montana watersheds due 

to Wyoming CBNG discharge, coal mines and the 

Tongue River Railroad would be the same under this 

alternative as under Alternative A. 

As discussed under Alternative A, Wyoming CBNG 

discharges in some watersheds will cause degradation 

of surface water quality and the exceedance of 

numerical standards. Degradation would also be 

caused due to severe increases in the flows of some 

streams. This degradation may cause beneficial uses 

to be impacted. As such, water management in 

Wyoming and Montana will likely need to be done 

differently than assumed under this alternative in 

order to protect Montana’s numerical and nondegradation surface water quality standards for EC, 

SAR and flow. The discharge of treated CBNG water

would dilute Wyoming CBNG discharges as these 

waters flow further into Montana. Cumulative effects 

on surface water could include localized erosion and 

stream alteration. These effects would be similar to 

those caused by major rain events, but they would 

last for the duration of the producing fields’ life. 

Effects from surface impoundments would be similar 

to effects under Alternative A.

Drawdown effects to groundwater would be the same 

as under Alternative B. 

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses 

Water produced from CBNG wells could be managed 

in a much broader fashion than has been analyzed in the 

previous alternatives by emphasizing beneficial use of 

CBNG water and MPDES requirements be met. A 

Water Management Plan (WMP) would be required 

prior to exploration or production. Water management 

options would include injection, treatment and 

discharge, impoundment, direct discharge, or other 

operator proposed methods, provided they are 

addressed in the WMP, the plan is approved by the 

appropriate agency and MPDES requirements are met. 

The WMP must address both site-specific conditions 

and cumulative effects of proposed water management 

methods. The plan would address the proposed water 

management practices and their effects on soil, water, 

vegetation, wildlife, stream channel stability and any 

other resources reasonably expected to be impacted by 

the actions. The WMP would be submitted in 

conjunction with Plans of Development (PODs) and

would need to be approved prior to or concurrent with 

the approval of any Applications for permit to Drill 

(APDs). Under this alternative, the Water Management 

Plan would be part of an Application for Permit to Drill 

and include certification that water well or spring 

mitigation agreements have been entered into with the 

owner(s) of any water well/spring within one mile. This 

is more comprehensive and thus more protective of 

potential impacts to existing groundwater sources. State 

law requires that an agreement be offered, consistent 

with existing State of Montana rules (MCA 82-11-175 

and MBOGC Order 99-99). 
CHAPTER 4

Hydrological Resources

4-114

Exploration

The volume of water generated by the testing of 

CBNG exploration wells would be stored in tanks or 

lined (clay or geotextile) impoundments to be 

disposed of under the appropriate permits. 

Impacts would be similar to those discussed under 

Alternative B.

Production

Water would be produced by each of the 

16,500 CBNG wells expected to be developed in the 

CBNG emphasis area. The maximum volume of 

CBNG water would be produced during year 6 with 

lesser volumes before and after this period. Unlike 

Alternative C, Alternative E allows for wide latitude 

in produced water management. The combination of 

emphasizing beneficial use and increased flexibility 

for managing produced water would likely increase 

water used for beneficial purposes, such as stock 

watering, irrigation, dust control, etc. Increases in 

beneficial use would also result in decreased impacts 

resulting from surface discharge as compared to 

Alternative C. Because actual management practices 

are yet to be defined as far as the level of beneficial 

use and alternate water management practices (e.g., 

surface discharge), Alternative E assumes 20 percent

will be used beneficially.

Impacts on groundwater under this alternative would 

be the same as in Alternative B. As discussed under 

impacts common to all alternatives, drawdown from 

CBNG could cause wells and springs which obtain 

their water from the developed coal seams to have 

reduced yields. It is anticipated the requirements for 

water mitigation agreements under MCA 82-11-175

and the protections provided by MCA 75-15-9, will 

mitigate these drawdown-related impacts.

Surface Water Analysis

The analyses that follow address the watersheds 

within the Montana portion of the Powder River

Basin. Although other watersheds may be impacted 

around the state as a result of CBNG development, 

the Powder River Basin is the area most likely to 

experience CBNG activity. Alternative E 

management options would maintain the beneficial 

uses of existing surface water resources in the 

Montana portion of the Powder River Basin. These 

beneficial uses will be protected through the MPDES 

permitting process under the CWA. The Montana 

BER standards are a part of this process.

The impacts calculated for this alternative are based 

on the results from the SWQATR, with modifications

resulting from the adoption of numerical standards 

for EC and SAR and for the definition of EC and 

SAR as harmful parameters. The 40 percent MMM 

criteria is also used in this analysis to limit flow 

increases in surface waters. Results are compared to 

surface water standards for EC and SAR were 

adopted by the Montana BER and EPA since the 

completion of the statewide document. Resultant 

water quality would not exceed these standards, 

except where existing water quality is in excess of 

these standards. Comparison to the standards is

provided under the analysis for each watershed if 

appropriate. 

Tongue River

The Tongue River could be impacted by current and 

future CBNG development in both the Wyoming and 

Montana portions of the Powder River Basin. The 

impact analysis discussed below is a summary of that 

analysis, using low mean monthly flows for 

comparison. This information for the Tongue River is 

summarized in Table 4-48. 

Water quality before and after mixing for the Decker 

Station is shown graphically in Figure 4-5. In this 

figure water qualities before and after mixing are 

shown for low mean monthly flows. The resulting

water qualities are plotted against the Ayers and 

Westcott criteria. The relationship between the 

resulting mixed waters can be compared to the 

following criteria:

• Northern Cheyenne Proposed Standards: Set at a 

SAR of 2.0 and an EC of 1,000 and 2,000 μS/cm 

at the south boundary of the Reservation. Surface 

water alteration forecasted under Alternative E 

would be below the tribe’s proposed limits 

except during 7Q10 flow. 

• Ayers and Westcot: The SWQATR discusses 

SAR versus EC plots as a way of determining 

potential impacts to soil texture after irrigation. 

The plot as shown in Figure 4-5 includes the 

boundary below which no impacts to soil are 

likely. Predicted water qualities during low mean 

monthly flows indicate that mixed waters will 

not cause infiltration impacts to soils under 

irrigation under Alternative E. 
CHAPTER 4

Hydrological Resources

4-115

TABLE 4-48 

EFFECTS ON SURFACE WATER FORECAST TO THE TONGUE RIVER

UNDER ALTERNATIVE E

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR EC

(μS/cm)

SAR EC

(μS/cm)

Flow

(cfs)

SAR EC 

(μS/cm)

Flow

(cfs)

SAR EC

(μS/cm)

Tongue River at 

Stateline Near 

Decker

3 1000 5 1500 178 0.86 731 183 1.93 773

Tongue River Near 

Birney Day School 3 1000 5 1500 183 1.09 863 190 2.52 912

Tongue River at 

Brandenburg Bridge 

Near Ashland, 

Montana

3 1000 5 1500 207 1.36 1016 214 2.5 1058

FIGURE 4-5 

WATER QUALITY PLOT BEFORE AND AFTER MIXING WITH WYOMING’S ALTERNATIVE 2A 

AND MONTANA’S ALTERNATIVE E CBNG DISCHARGES 

TONGUE RIVER NEAR DECKER, MONTANA

0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000

SAR

EC (uS/cm)

Stream Water Quality Before and After Mixing with CBM 

Produced Water for 7Q10 and Mean Monthly Flows

Irrigation Season WQ Before Mixing with CBM 

Water

Irrigation Season WQ After Mixing with CBM 

Water

Non-Irrigation Season WQ After Mixing with CBM 

Water

Non-Irrigation Season WQ Before Mixing with 

CBM Water

7Q10 WQ after Mixing with CBM Water

7Q10 WQ Before Mixing with CBM Water

Irrigation WQ Threshold

Non-Irrigation Season WQ Standard

Irrigation Season WQ Standard



WQ=Water Quality

Source: Surface Water Quality Analysis Technical Report
CHAPTER 4

Hydrological Resources

4-116

• MDEQs Irrigation Season Standards (MT-Irr): 

These standards are set at a SAR of 3.0 and an 

EC of 1000 μS/cm for the Tongue River. The 

forecasted surface water quality under 

Alternative E during minimum mean monthly 

flows is below these SAR standards for all 

stations and below these EC standards for all 

stations except for the station at Brandenburg 

Bridge. Existing conditions at Brandenburg 

Bridge during minimum mean monthly flows are 

also in excess of this standard. The 40 percent

non-degradation analysis threshold for EC (400 

μS/cm) is exceeded by existing conditions and

the resulting surface water quality would 

increase this exceedance. The 40 percent nondegradation analysis threshold for SAR (1.2) is 

exceeded by existing conditions at the 

Brandenburg station and the forecasted impacts 

under this alternative would cause it to be 

exceeded at all stations.

• MDEQ Non-Irrigation Season Standards (MTNon): These standards are set at a SAR of 5.0 

and an EC of 1500 μS/cm for the Tongue River. 

The forecasted surface water quality under 

Alternative A during minimum mean monthly 

flows is below these SAR and EC standards for 

all stations. The 40 percent non-degradation 

analysis threshold for EC (600 μS/cm) is 

exceeded by existing conditions and the resulting 

surface water quality would increase this 

exceedance. The 40 percent non-degradation 

analysis threshold for SAR (2) is not exceeded 

by existing conditions at any stations; however 

the forecasted impacts under this alternative 

would cause it to be exceeded at the Birney Day 

School and Brandenburg stations.

• 40 percent MMM: This analysis threshold would 

be 249 cfs at Decker, 256 cfs at Birney Day 

School and 290 cfs at Brandenburg. This 

analysis threshold is not exceeded at any station.

The Tongue River is an important source of irrigation 

water in the Powder River Basin. The effects on the 

Tongue River would be the same as those for 

Alternative A, since no untreated Montana CBNG 

discharge to the Tongue would be assumed under this 

alternative analysis, besides discharge in accordance 

with the existing CX Ranch MPDES permit. This 

permit allows for 1,600 to 2,500 gpm of untreated 

CBNG discharge from up to 15 locations. This 

grandfathered permit causes some degradation of 

surface water quality. There would be no impact to 

beneficial uses under this alternative since surface 

water quality standards are not projected to be 

exceeded.

Of the 33,282 gpm predicted to be produced during 

year six of the RFD, approximately 31,682 gpm will 

need to be managed by means other than untreated 

surface discharge. As mentioned previously it is 

assumed that 20 percent of all produced water would 

be used for beneficial uses. Other water management 

options, anticipated to be used on a site-specific basis 

include infiltration basins, injection wells, water 

treatment and lined evaporation basins. These same 

water management practices are assumed for all 

watersheds analyzed. It should be noted that this 

distribution of water management practices is 

intended only for use in this analysis and is not 

intended to prescribe water management practices for 

any particular project. Any properly permitted water 

management alternatives can be used. A site specific 

Water Management Plan will need to be developed 

for each project under Alternative E and may include 

any, all, or none of the water management methods 

listed above.

Surface disturbance from water management 

activities are covered under the Assumptions section 

of Chapter Four. These ground disturbing activities 

would result in slight short term increases in 

sediment yield and suspended sediment loads until 

vegetation becomes reestablished. Effects from 

impoundments are discussed under Alternative A.

Effects from injection facilities are discussed under 

Alternative B. Effects from surface discharge of 

treated water might include changes to stream flow, 

erosion and sedimentation, especially where 

discharge occurs to ephemeral or intermittent 

drainages. Hanging Woman Creek is an impaired 

waterbody due to siltation; surface discharge of 

treated water may need to be limited in this drainage. 

Little Bighorn and Bighorn Rivers

The Bighorn River and its tributary, the Little 

Bighorn, are not expected to be affected by Wyoming 

CBNG development, but are expected to be affected 

by CBNG wells on Indian Lands and state and 

private lands in Montana. 

The resultant surface water impacts to the Bighorn 

rivers would be similar to but less than Alternative C. 

The actual volume of water that is allowed to be 

discharged will depend on the water quality standards 

set by the Montana Board of Environmental Review

and the MPDES permit program administered by the 

MDEQ. CBNG discharge volumes will be dependent 

on site-specific conditions and the approval of a 

WMP. In order to be approved the WMP would need 

to show how the produced water could be managed 
CHAPTER 4

Hydrological Resources

4-117

without impacting beneficial uses. These results are 

shown in Table 4-49 and can be compared to the 

following surface water criteria:

• Ayers and Westcot: Predicted water qualities 

would only exceed this criterion during 7Q10 

flows and only at the upstream stations under 

this alternative.

• EC and SAR standards have not been developed 

for these waters.

• 40 percent MMM: This analysis threshold would 

be 154 cfs at Wyola, 172 cfs at Hardin and 2132 

cfs at Bighorn. This analysis threshold is not 

exceeded at any station.

Surface water would be degraded under this 

alternative; however there would not be anticipated 

impacts to beneficial uses since standards would not 

be exceeded. Additional impact analyses are 

presented in the SWQATR.

The water management in the Bighorn Watershed is 

assumed to be similar to the Tongue; however since 

discharges would be under the National Pollutant 

Discharge Elimination System (NPDES) program, 

some untreated discharge could occur. Surface 

disturbance from water management activities are 

covered under the Assumptions section of Chapter 4. 

These ground disturbing activities would result in 

slight short term increases in sediment yield and

suspended sediment loads until vegetation becomes 

reestablished. Effects from impoundments are 

discussed under Alternative A. Effects from injection

facilities are discussed under Alternative B. Effects 

from surface discharge of treated water might include 

changes to stream flow, erosion and sedimentation, 

especially where discharge occurs to ephemeral or 

intermittent drainages. 

Rosebud Creek

Rosebud Creek is not expected to be affected by 

Wyoming CBNG wells and because Rosebud Creek 

contains such high quality water at such low flow 

rates, there is expected to be no discharge of Montana 

CBNG water into Rosebud Creek under the analysis 

of Alternative E. For comparison purposes, these 

forecasted effects are summarized on Table 4-50. 

The effects on Rosebud Creek would be the same as 

those for Alternative A, since no additional Montana 

discharges to Rosebud Creek are assumed under this 

alternative. A comparison to surface water quality 

criteria is provided in the discussion of Rosebud 

Creek under Alternative A. As there would be no 

discharge under this alternative there would be no 

degradation of beneficial uses. 

The water management in the Rosebud Watershed is 

assumed to be similar to that in the Tongue; however 

no treated or untreated discharges would occur. 

Surface disturbance from water management 

activities are covered under the Assumptions section 

of Chapter 4. These ground disturbing activities 

would result in slight short term increases in 

sediment yield and suspended sediment loads until 

vegetation becomes reestablished. Effects from 

impoundments are discussed under Alternative A.

Effects from injection facilities are discussed under 

Alternative B.

TABLE 4-49 

EFFECTS ON SURFACE WATERS OF THE LITTLE BIGHORN AND BIGHORN RIVERS

UNDER ALTERNATIVE E

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Little Bighorn River 

at Wyola N/A N/A N/A N/A 110 0.53 548 115 2.26 – 

2.64 623-632

Little Bighorn River 

at Hardin N/A N/A N/A N/A 123 0.99 768 133 3.94-

4.59 881-896

Bighorn River at 

Bighorn N/A N/A N/A N/A 1523 2.08 952 1542 2.54-

2.64 968-970
CHAPTER 4

Hydrological Resources

4-118

TABLE 4-50

EFFECTS ON SURFACE WATER IN THE ROSEBUD CREEK

UNDER ALTERNATIVE E 

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Rosebud Creek at Kirby 3 1000 5 1500 1.78 0.77 1016 1.78 0.77 1016

Rosebud Creek at 

Rosebud 3 1000 5 1500 8.42 4.84 1780 8.42 4.84 1780

Little Powder River

The effects on the Little Powder River surface water 

quality at the Weston, Wyoming, station would be 

the same as Alternative A, since there are no 

Montana wells discharging upstream of this station. 

The effects from Montana wells downstream of this 

station are calculated in the analysis for the Powder 

River at Locate station. 

The water management in the Little Powder 

Watershed is assumed to be similar to that in the 

Tongue. Surface disturbance from water management 

activities are covered under the Assumptions section 

of Chapter 4. Effects from impoundments are 

discussed under Alternative A. These ground 

disturbing activities would result in slight short term 

increases in sediment yield and suspended sediment 

loads until vegetation becomes reestablished. Effects 

from injection facilities are discussed under 

Alternative B. Effects from surface discharge of 

treated water might include changes to stream flow, 

erosion and sedimentation, especially where 

discharge occurs to ephemeral or intermittent 

drainages. 

Powder River

The impacts to the Powder River watershed are 

shown in Table 4-51; impacts to EC, SAR and flow 

will come from discharges to the river from 

Wyoming CBNG development As the increase in 

flow which result from Wyoming CBNG 

development are projected to exceed the 40%MMM 

analysis threshold, it is not anticipated that any 

discharge of treated or untreated CBNG water will be 

allowed in Montana. These resulting surface water 

qualities can be compared to the following surface 

water criteria:

• Ayers and Westcot: This criterion would only be 

exceeded during 7Q10 flows under this 

alternative

• MT-Irr: These standards are set at a SAR of 5.0 

and an EC of 2,000 μS/cm for the Powder River. 

The forecasted surface water quality under 

Alternative E during minimum mean monthly 

flows would be above the SAR and EC 

standards. Existing conditions also exceed this 

EC standard. An authorization to degrade would 

be needed from the MDEQ for development to 

occur in this manner. As such, it is anticipated 

the adopted SAR standard will severely curtail 

untreated CBNG discharges in the Powder River 

watershed. In Montana MPDES permits are 

required and these permits would need to 

incorporate the Montana BER standards. As 

such, CBNG discharges which would cause the 

mean monthly SAR to exceed 5.0 would not be 

allowed. Wyoming CBNG development may 

also need to proceed differently than assumed 

under Wyoming's Alternative 2A in order to 

prevent violation of the Montana BER standards 

at the state line. The 40 percent non-degradation 

analysis threshold for EC (800 μS/cm) is 

exceeded by existing conditions at both stations

and the resulting surface water quality would 

increase this exceedance. The 40 percent nondegradation analysis threshold for SAR (2) is 

exceeded by existing conditions at both stations

and the resulting surface water quality would 

increase this exceedance.
CHAPTER 4

Hydrological Resources

4-119

TABLE 4-51

EFFECTS ON SURFACE WATER IN THE POWDER RIVER

UNDER ALTERNATIVE E

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water Quality 

and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Powder River at 

Moorhead 5 2000 6.5 2500 145 4.65 2154 224 10.7 2230

Powder River at Locate 5 2000 6.5 2500 143 4.61 2287 236 11.36 2320

• MT-Non: These standards are set at a SAR of 6.5 

and an EC of 2,500 μS/cm for the Powder River. 

The forecasted surface water quality under 

Alternative E during minimum mean monthly 

flows is above this SAR standard and below the 

EC standard. An authorization to degrade would 

be needed from the MDEQ for development to 

occur in this manner. MDEQ has never approved 

an authorization to degrade. As such, it is 

anticipated the adopted SAR standard will 

severely curtail untreated CBNG discharges in 

the Powder River watershed. In Montana 

MPDES permits are required and these permits 

would need to incorporate the Montana BER

standards. As such, CBNG discharges which 

would cause the mean monthly SAR to exceed 

6.5 would not be allowed. Wyoming CBNG 

development may also need to proceed 

differently than assumed under Wyoming's 

Alternative 2A in order to prevent violation of 

the Montana BER standards at the state line. The 

40 percent non-degradation analysis threshold

for EC (1000 μS/cm) is exceeded by existing 

conditions at both stations and the resulting 

surface water quality would increase this 

exceedance. The 40 percent non-degradation 

analysis threshold for SAR (2.6) is exceeded by 

existing conditions at both stations and the 

resulting surface water quality would increase 

this exceedance.

• 40 percent MMM: This analysis threshold would 

be 203 cfs at Moorhead and 200 cfs at Locate. 

This analysis threshold would be exceeded at 

both stations.

The Powder River watershed is unique to the PRB in 

Montana; the existing water is seasonally variable 

and often of low quality, there is significant CBNG 

discharge to this river in Wyoming at the present time 

that does not appear to be impacting the river [see 

Appendix E in the SWQATR Greystone 2002)] and

CBNG water quality data in the Montana portion of 

the watershed is limited. 

CBNG producers in the Wyoming portion of this 

watershed will be held to the Montana BER standards 

at the state line since these standards have CWA 

standing. 

There would not be anticipated impacts to beneficial 

uses under this alternative since MPDES permits

must incorporate all applicable surface water 

standards. The WYDEQ has also modified its 

permitting process to prevent exceedance of 

Montana’s standards at the stateline.

The water management in the Powder River

Watershed is assumed to be similar to the Tongue; 

however no treated or untreated discharges could 

occur in Montana. Surface disturbance from water 

management activities are covered under the 

Assumptions section of Chapter 4. These ground 

disturbing activities would result in slight short term 

increases in sediment yield and suspended sediment 

loads until vegetation becomes reestablished. Effects 

from impoundments are discussed under Alternative 

A. Effects from injection facilities are discussed 

under Alternative B. 

Mizpah Creek

Table 4-52 illustrates the small amount of water 

within Mizpah Creek. Only 125 Montana CBNG 

wells are projected to be productive in this 

watershed; and there are no Wyoming CBNG wells. 

Impacts are expected to be similar under Alternative 

E as under Alternative A, since only CBNG water 

which had been treated to ambient water quality 

could be discharged. Beneficial uses would not be 

reduced. 
CHAPTER 4

Hydrological Resources

4-120

The water management in the Mizpah Creek

Watershed is assumed to be similar to the Tongue. 

Surface disturbance from water management 

activities are covered under the Assumptions section 

of Chapter 4. Effects from impoundments are 

discussed under Alternative A. These ground 

disturbing activities would result in slight short term 

increases in sediment yield and suspended sediment 

loads until vegetation becomes reestablished. Effects 

from injection facilities are discussed under 

Alternative B. Effects from surface discharge of 

treated water may have noticeable effects on stream 

flow, erosion and sedimentation in this watershed, 

especially where discharge occurs to ephemeral or 

intermittent drainages. 

Yellowstone River

The Yellowstone River receives the combined flows 

of all the other watersheds in the Montana portion of 

the Powder River Basin. The Forsyth station is the 

upstream station which receives no contribution from 

Wyoming discharges, but will receive some Montana

CBNG discharge. The Sidney station is the 

downstream station and it will receive discharges 

from all Montana Powder River Basin wells and 

approximately 21,391 CBNG wells from the 

Wyoming portion of the Powder River Basin under 

Alternative E. 

The effects to the Yellowstone River would be less 

than those indicated for Alternative C as the volume 

of CBNG water discharged to tributaries of the 

Yellowstone would be limited. Table 4-53 

summarizes the effects of these discharges on the 

Yellowstone River. These resultant surface water 

chemistries can be compared to the following criteria.

• Ayers and Westcot: Predicted water qualities 

would not exceed this criterion even during 

7Q10 flows.

• EC and SAR standards have not been developed 

for these waters. 

• 40 percent MMM: This analysis threshold would 

be 8148 cfs at Forsyth and 8070 cfs at Sidney. 

This analysis threshold is not exceeded at either 

station.

Surface water would be slightly altered under this 

alternative; however there would not be anticipated 

impacts to beneficial uses. Additional impact 

analyses are presented in the SWQATR.

TABLE 4-52 

EFFECTS ON SURFACE WATERS OF MIZPAH CREEK DRAINAGE 

UNDER ALTERNATIVE E

Station

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water 

Quality and Quantity (Min. 

Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly) 

SAR EC SAR EC Flow SAR EC Flow SAR EC

Mizpah Creek at Mizpah 3 500 5 500 0.26 16.6 3503 0.26 16.6 3503

TABLE 4-53

EFFECTS ON SURFACE WATER IN THE YELLOWSTONE RIVER UNDER ALTERNATIVE E

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water 

Quality and Quantity

(Min. Mean Monthly)

Resulting Stream Water Quality 

and Quantity 

(Min. Mean Monthly) 

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC

(μS/cm)

Yellowstone at 

Forsyth, Montana N/A N/A N/A N/A 5820 1.99 745 5851 2.22 – 2.18 753 – 754

Yellowstone at 

Sidney, Montana N/A N/A N/A N/A 5764 2 870 5848 2.54 – 2.60 891 – 893
CHAPTER 4

Hydrological Resources

4-121

The water management in the Yellowstone River

Watershed as a whole is assumed to be similar to the 

Tongue. Surface disturbance from water management 

activities are covered under the Assumptions section 

of Chapter 4. Effects from impoundments are 

discussed under Alternative A. These ground 

disturbing activities would result in slight short term 

increases in sediment yield and suspended sediment 

loads until vegetation becomes reestablished. Effects 

from injection facilities are discussed under 

Alternative B. Effects from surface discharge of 

treated water might include changes to stream flow, 

erosion and sedimentation, especially where 

discharge occurs to ephemeral or intermittent 

drainages.

Summary of Surface Water Impacts

A summary of calculated surface water effects by 

USGS station for Alternative E is shown in 

Table 4-54. The table summarizes effects of forecast 

discharges of CBNG water from the Wyoming 

Alternative 2A and Montana's Alternative E for 

watersheds in the Montana portion of the Powder 

River Basin. Surface water quality in some 

watersheds would be slightly degraded; however, 

downstream uses would not be diminished. Surface 

water flow would be moderately increased causing 

some riparian erosion, as well as increased 

sedimentation. In some watersheds these increases in 

flow would be in excess of the 40 percent MMM 

analysis threshold. 

TABLE 4-54 

CUMULATIVE IMPACTS ON SURFACE WATERS UNDER WYOMING’S ALTERNATIVE 2A AND 

MONTANA’S ALTERNATIVE E

MDEQ Surface 

Water Quality 

Standards 

Irrigation Season

MDEQ Surface 

Water Quality 

Standards NonIrrigation Season

Existing Stream Water 

Quality and Quantity

(Min. Mean Monthly)

Resulting Stream Water 

Quality and Quantity 

(Min. Mean Monthly)

Station SAR

EC

(μS/cm) SAR

EC

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Flow

(cfs) SAR

EC 

(μS/cm)

Tongue River at 

Stateline Near 

Decker

3 1000 5 1500 178 0.86 731 183 1.93 773

Tongue River Near 

Birney Day School 3 1000 5 1500 183 1.09 863 190 2.52 912

Tongue River at 

Brandenburg Bridge 

Near Ashland, Mt.

3 1000 5 1500 207 1.36 1016 214 2.5 1058

Little Bighorn River 

at Wyola N/A N/A N/A N/A 110 0.53 548 115 2.26 – 

2.64

623 - 

632

Little Bighorn River 

at Hardin N/A N/A N/A N/A 123 0.99 768 133 3.94-

4.59 881-896

Bighorn River at 

Bighorn N/A N/A N/A N/A 1523 2.08 952 1542 2.54-

2.64 968-970

Rosebud Creek at 

Kirby 3 1000 5 1500 1.78 0.77 1016 1.78 0.77 1016

Rosebud Creek at 

Rosebud 3 1000 5 1500 8.42 4.84 1780 8.42 4.84 1780

Little Powder River

Stateline Weston, 5 2000 6.5 2500 2.6 6.94 3300 16 10.41 1606

Powder River at 

Moorhead 5 2000 6.5 2500 145 4.65 2154 224 10.7 2230

Powder River at 

Locate 5 2000 6.5 2500 143 4.61 2287 236 11.36 2320

Mizpah Creek at 

Mizpah 3 500 5 500 0.26 16.6 3503 0.26 16.6 3503

Yellowstone at 

Forsyth, Montana N/A N/A N/A N/A 5820 1.99 745 5851 2.18 – 

2.22

753 – 

754

Yellowstone at 

Sidney, Montana N/A N/A N/A N/A 5764 2 870 5848 2.54 – 

2.60

891 - 

893
CHAPTER 4

Hydrological Resources

4-122

The adoption of the Montana BER numerical 

standards since completion of the Statewide 

document and the non-degradation rules will reduce 

impacts to surface water quality from CBNG, 

particularly in the Powder River watershed. These 

standards are not anticipated to be exceeded, except 

where existing conditions exceed these standards. As 

such, beneficial uses of surface waters will not be 

impacted.

Abandonment

Impacts to water resources due to abandonment 

operations would be similar to impacts under 

Alternative B. When the estimated 16,500 CBNG 

production wells are abandoned over the 20-year 

project life, 33,000 acres of soil would be disturbed

and reclaimed. This disturbed soil would be 

vulnerable to erosion and the resulting suspended 

material could be washed into adjacent surface waters 

unless mitigating measures are employed. The 

implementation of BMPs would reduce soil erosion 

until groundcover and original conditions are 

restored. 

Crow Reservation

Surface water effects on tribal lands under 

Alternative E would be similar to, but less than, those 

effects noted in Alternative C. The wider variety of 

water management options would lessen the effects 

from produced water. Groundwater effects within the 

reservation boundary would be identified and 

controlled by monitoring and production restrictions. 

The monitoring would track drawdown of aquifers 

from CBNG production on federal leases outside the 

reservation boundary. If drawdown is detected, the 

production rate of CBNG wells on federal leases 

would be restricted. 

Northern Cheyenne

Surface water effects to Northern Cheyenne Tribal 

Lands under Alternative E would be similar to those 

impacts noted in Alternative A, since no additional 

direct discharge of CBNG water is assumed to occur 

in the Tongue River or Rosebud Creek. The 

beneficial use of the Tongue and Rosebud streams 

would be maintained under Alternative E. 

CBNG developments have the potential to impact 

groundwater resources under tribal lands. 

Groundwater impacts within the reservation 

boundary would be detected and managed by 

monitoring the magnitude of aquifer drawdown. The 

monitoring wells would be engineered and placed to 

best intercept drawdown effects from CBNG 

development. Nests of monitoring wells will be used 

to track drawdown of multiple producing coal seams. 

The USGS has installed six well clusters along the 

southern boundary of the reservation. The BLM has

also installed monitoring well clusters throughout the 

Montana portion of the Powder River Basin, 

including areas adjacent to the Northern Cheyenne

and Crow reservations. The BLM wells will provide 

regional hydrological information as well as locally 

important data. In addition, CBNG operators are

required to monitor groundwater levels within CBNG 

fields. The entire monitoring well network would 

monitor drawdown of coal seams and surface 

aquifers. Monitoring well data would be placed in the 

public record by the USGS, the BLM and responsible 

state agencies where it can be accessed and used by 

tribal officials as well as agency staff.

If drawdown is detected on the reservation, the 

production rate of CBNG wells operated on federal 

leases would be restricted until mitigation measures

can be put into place. Mitigation measures could 

include curtailment of CBNG production, 

replacement of affected water wells or springs, or a 

hydrologic barrier engineered to reduce additional 

drawdown. The BLM would use all reasonable 

means to assure that reservation groundwater is not 

adversely affected by off-reservation CBNG 

production. Mitigation measures would substantially 

reduce drawdown originating from federal mineral 

leases, but the potential still exists for CBNG wells 

on nearby state and private leases to drawdown 

groundwater within the reservation boundaries. 

Conclusion

Effects of Alternative E to groundwater will be the 

same as Alternative B. Minor effects on shallow 

groundwater quality from impoundment infiltration 

and surface discharge of some untreated production 

water would also occur. The operator’s WMPs would 

result in increased beneficial use of produced CBNG

water, estimated to total at least 20 percent. 

Cumulative impacts to Montana watersheds due 

Wyoming CBNG discharge, coal mines and the 

Tongue River Railroad would be the same under this 

alternative as under Alternative A.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. Anticipated impacts 

under this alternative include slight degradation of 

surface water quality, without diminishing 

downstream use.
CHAPTER 4

Hydrological Resources

4-123

Weathered landscape with exposed Fort Union Formation

Alternative F—Phased Development 

Multiple Screens (High Range)

Water produced from CBNG wells could be managed 

similar to that in Alternative E by emphasizing 

beneficial use of CBNG water while assuring 

MPDES as well as Phased Development 

requirements are met. Under this alternative 

statewide and watershed-wide phased development 

rules limit the timing of development within each

watershed. Furthermore, there may be a decrease of 

2,333 wells drilled if development does not occur 

within crucial sage-grouse habitat areas. The decrease 

in wells would primarily occur within the Upper 

Tongue watershed and to a lesser degree within the 

Lower Tongue and Middle Powder watersheds.

In addition to the timing factor, cumulative surface 

discharge of untreated CBNG water in any watershed 

is limited to 10 percent of the 7Q10 value. This limit 

would apply to intermittent and ephemeral tributaries 

as well as main stems. For example, the 7Q10 value 

for the Powder River at Locate is 1.6 cfs, so the total 

CBNG discharge into the Powder River watershed 

could be no greater than 0.16 cfs (72 gpm). Hanging 

Woman Creek is an intermittent stream, so its 7Q10 

is zero, thus no untreated discharge from federal 

wells would be allowed in that drainage. For 

watershed totals see Table 4-55. If untreated 

discharge from Wyoming CBNG were greater than 

this limit, no untreated water would be discharged 

from federal CBNG wells in the Montana portion of

the watershed. If pre-existing federal, state and 

private CBNG wells accounted for more than the 

untreated discharge limit, there could be no 

additional untreated discharge from federal CBNG 

wells. This analysis threshold would not be a limiting 

factor at this time since EC and SAR have been 

determined by the Montana BER to be harmful 

parameters which are regulated by the nondegradation rules. Since ambient water quality is 

greater than 40 percent of the standards in all 

watersheds, no untreated CBNG discharge would be 

allowed in Montana.

A WMP would be required prior to any exploration 

or production, listing the manner in which forecasted

produced water would be managed. MPDES 

requirements must be met prior to any discharges 

(treated or untreated). The WMP must address both 

site-specific conditions and cumulative effects of 

proposed water management methods. The plan 

would address the proposed water management 

practices and their effects on soil, water, vegetation, 

wildlife, stream channel stability and any other 

resources reasonably expected to be impacted by the 

actions. The WMP would be submitted in 

conjunction with PODs and would need to be 

approved prior to or concurrent with the approval of 

any Applications for Permit to Drill (APDs).
CHAPTER 4

Hydrological Resources

4-124

TABLE 4-55

WATERSHED UNTREATED DISCHARGE LIMITS

Watershed

Most Downstream Station 

with Adequate Data

7Q10

(cfs)

10% of 7Q10

(cfs)

10% of 7Q10

(gpm)

Bighorn River Bighorn near Bighorn 870 87 39,046

Rosebud Creek Rosebud near Rosebud 0 0 0 

Tongue River Tongue River at 

Brandenburg Bridge 70 7 3,142

Powder River Powder River at Locate 1.6 0.16 72

Exploration

The volume of water generated by the testing of 

CBNG exploration wells would be stored in tanks or 

lined impoundments to be disposed of under the 

appropriate permits. 

Impacts from exploration would be similar to those 

discussed under Alternative B.

Production

Water would be produced by each of the 

16,403 CBNG wells expected to be developed in the 

CBNG Planning Area. Unlike Alternatives B through 

E, the maximum volume of CBNG water would vary 

from watershed to watershed depending upon the 

drilling allowed by the Phased Development plan. 

It is assumed that initially, drilling on state and 

private minerals will account for much of the CBNG 

drilling allowed. Because actual management 

practices are yet to be defined as far as the level of 

beneficial use and alternate water management 

practices (e.g., surface discharge), Alternative F, like 

Alternative E, assumes 20 percent will be used 

beneficially.

Produced water could be managed by a variety of 

means. Any discharges to surface waters would need 

to meet MPDES requirements. For this analysis it is 

assumed non-degradation rules for EC, SAR and

flow will be applicable. The EC and SAR nondegradation rules will require all Montana CBNG 

discharges be treated prior to discharge. It is assumed 

Wyoming development will follow their Alternative 

2A, except they will need to meet the numerical 

surface water quality standards at the stateline. Forty 

percent of the minimum MMM flow is used for 

analysis purposes to indicate where cumulative flow 

changes would trigger a significance determination 

by the MDEQ under the non-degradation rules for 

flow. The actual point at which this determination is 

made will depend on the specific information 

available at the time when an application is made for 

a MPDES permit. Water management practices other 

than treated discharge to surface waters include 

beneficial use, injection, impoundment and any other 

properly permitted water management practice.

Impacts from impoundments would be similar to 

those described under Alternative A; however the 

amount of surface disturbances would be 

commensurate with the increased number of potential 

impoundments similar to Alternative E. 

Because of the conditions for development within the 

crucial sage-grouse habitat areas, a lower level of 

development is anticipated to occur over 

approximately 93,529 acres of which 78,982 acres 

are in the Upper Tongue watershed, 11,820 acres are 

in the Lower Tongue watershed and 2,727 acres are 

in the Middle Powder watershed. This would 

represent a decrease of 1970 wells drilled in the 

Upper Tongue watershed, 295 wells in the Lower 

Tongue watershed and 68 wells in the Middle 

Powder watershed. If development does not occur 

within the crucial sage-grouse habitat then the 

quantity of CBNG produced water would be 

decreased in proportion to the number of fewer wells 

drilled for the three watersheds which contain crucial 

sage-grouse habitat. Additionally, if development 

does not occur within the crucial sage-grouse habitat 

areas then the drawdown of groundwater would be 

locally lessened around these areas.

Impacts on groundwater under this alternative would 

be the same as in Alternative B. As discussed under 

impacts common to all alternatives, drawdown from 

CBNG could cause wells and springs which obtain 

their water from the developed coal seams to have 

reduced yields. It is anticipated the requirements for 

water mitigation agreements under MCA 82-11-175
CHAPTER 4

Hydrological Resources

4-125

and the protections provided by MCA 75-15-9, will 

mitigate these drawdown-related impacts. 

Surface Water Analysis

The analyses that follow address the watersheds 

within the Montana portion of the Powder River

Basin. Although other watersheds may be impacted 

around the state as a result of CBNG development, 

the Powder River Basin is the area most likely to 

experience CBNG activity. The Alternative F 

management option would maintain the beneficial 

uses of existing surface water resources in the 

Montana portion of the Powder River Basin. The 

number of APDs listed for each watershed is in Table 

4-1. Under this alternative the MDEQ’s nondegradation analysis thresholds for EC, SAR and 

Flow would apply to discharges in Montana while 

Wyoming development would operate under their 

Alternative 2A. The 10 percent of 7Q10 untreated 

discharge threshold is maintained for this alternative; 

however it would not be an issue unless either EC or 

SAR were determined to be non-harmful parameters 

since new untreated discharges would not be allowed 

in Montana due to non-degradation standards. 

Therefore the 10 percent of 7Q10 untreated discharge 

threshold is not a part of this analysis, but rather 

provides an additional level of assurance due to the 

transitional nature of CBNG rules in Montana at this 

time. Treated discharges will be held to ambient 

water quality.

For analysis purposes it is assumed that for this 

alternative 20 percent of the produced water will be 

used beneficially and the rest will be treated and 

discharged unless MPDES permits are limited due to 

the MDEQ’s cumulative non-degradation standard 

for flow (assumed in this analysis to be encountered 

at 40 percent MMM). If the flow limit is encountered, 

the remaining CBNG water would be managed by 

other options, which this analysis assumed to be split 

as 40 percent evaporation basins, 30 percent

infiltration basins and 30 percent injection. This split 

is for analysis purposes only and is in no way 

intended to limit properly permitted water 

management options.

Tongue River

The Tongue River could be impacted by current and 

future CBNG development in both the Wyoming and 

Montana portions of the Powder River Basin. The 

peak rate of water production from Montana CBNG 

wells in the Tongue River watershed under 

Alternative F would occur in year 7 when 29,832 

gpm would be produced. Twenty percent of this 

produced water (5,966 gpm) is assumed to be used 

for beneficial uses. 

Conditions placed on the development of CBNG 

within crucial sage-grouse habitat may result in less 

CBNG water being produced and potentially being 

discharged to the Tongue River. There are 78,982 

acres of crucial sage-grouse habitat within the Upper 

Tongue River watershed and 11,820 acres within the 

Lower Tongue watershed.

Impacts from water management activities will be 

similar to E. No additional untreated Montana CBNG 

surface discharge to the Tongue would be assumed 

under this alternative. One existing permit allows for 

1,600 to 2,500 gpm of untreated CBNG discharge 

from up to 15 locations. Therefore, the surface water 

quality impacts will be similar to those listed under 

Alternative E. 

The Tongue River is an important source of irrigation 

water in the Powder River Basin. The existing 

permits are anticipated to cause an unnoticeable 

amount of alteration in water quality and there would 

not be anticipated impacts to beneficial uses under 

this alternative since standards would not be 

exceeded. Any future MPDES permits for untreated 

discharge would require an authorization to degrade. 

Little Bighorn and Bighorn Rivers

The Bighorn River and its tributary, the Little 

Bighorn, are not expected to be affected by Wyoming 

CBNG development, but are expected to be affected 

by CBNG wells on state, private and federal lands in 

Montana. 

The resultant surface water quality impacts to the 

Bighorn rivers would be between those identified for 

Alternatives D and E since untreated discharge is 

anticipated under the Preferred Alternative only on 

the Crow Reservation. Untreated discharges could 

occur on the Crow Reservation, provided appropriate 

NPDES permits were obtained from the EPA. The 

EPA has not developed standards for EC or SAR and

Montana’s “harmful” designation for these 

parameters has not been approved by the EPA,

leaving it unenforceable upstream onto the Crow 

Reservation. NPDES permits issued by EPA would 

need to meet Montana’s numerical standards for EC 

and SAR (which have been approved under the 

CWA) at the reservation boundary. The expected 

discharges would be much less than the 40 percent 

MMM analysis threshold. The disturbance associated 

with these water management activities would be 

comparable to that estimated under Alternative E.

Actual CBNG discharge volumes will be dependent 

on site-specific conditions and the approval of a 
CHAPTER 4

Hydrological Resources

4-126

WMP. In order to be approved the WMP would need 

to show how the produced water could be managed 

without impacting beneficial uses. MPDES/NPDES

permits will be required prior to the approval of 

WMPs. As such, there would be no impact to 

beneficial uses under this alternative.

The slight increases in flow which would result from 

treated discharges may result in slight changes to 

physical stream conditions. 

Rosebud Creek

Rosebud Creek is not expected to be affected by 

Wyoming CBNG wells and because Rosebud Creek 

contains such high quality water at such low flow 

rates, there is expected to be no untreated discharge 

of Montana CBNG water into Rosebud Creek under 

the analysis of Alternative F. Limited discharge of 

treated water could occur but the 40 percent MMM 

analysis threshold is the limiting factor. As there 

would be no untreated discharge under this 

alternative, the resulting water quality would be the 

same as Alternative D and there would be no 

degradation of beneficial uses. Other management 

practices such as injection, infiltration, beneficial use

and evaporation will also need to be utilized.

The moderate increases in flow which would result 

from treated discharges may result in slight changes 

to physical stream conditions. 

Little Powder River

The Little Powder watershed is the site of CBNG 

development in Wyoming but the most prospective

portion of the Fort Union Formation (the Tongue 

River Member) is sparsely present under this 

watershed in Montana. Because of the distribution of 

the Fort Union, little CBNG exploration and 

production is expected to occur in the Montana 

portion of the watershed. The quality of the Little 

Powder River exceeds the numerical standards of the 

MDEQ and it is an intermittent stream (7Q10=0).

Therefore, no untreated discharges are expected 

under Alternative F. Other management practices 

such as injection, infiltration, beneficial use and

evaporation will need to be utilized. The disturbance 

associated with these water management activities 

would be comparable to that estimated under 

Alternative E. Impacts would be the same as 

Alternative A and there would be no degradation of 

beneficial uses. 

The slight increases in flow which would result from 

treated discharges may result in minor changes to 

physical stream conditions. 

Powder River

Alternative F assumes 100 percent of potential 

CBNG discharge (40 percent MMM) would be taken 

up by Wyoming development, therefore none of the 

water produced in Montana would be discharged 

under this alternative. The impacts to surface water 

quality under Alternative F will be similar to those 

identified for Alternative D, except discharges would 

be limited by the 40 percent MMM analysis 

threshold. Other management practices such as 

injection, infiltration, beneficial use and evaporation 

will need to be utilized. The disturbance associated 

with these water management activities would be 

comparable to that estimated under Alternative E.

Conditions placed on the development of CBNG 

within crucial sage-grouse habitat may result in less

CBNG water being produced and potentially being 

discharged to the Powder River. There are 2,727 

acres of crucial sage-grouse habitat within the Middle 

Powder River watershed.

Mizpah Creek

Impacts to surface waters are expected to be similar 

to Alternative A since no untreated CBNG produced 

water could be discharged under this alternative and

treated discharges would be limited by the 40 percent

MMM analysis threshold. Other management 

practices such as injection, infiltration, beneficial use

and evaporation will need to be utilized. The 

disturbance associated with these water management 

activities would be comparable to that estimated 

under Alternative E. Beneficial uses would not be 

reduced. 

The slight increases in flow which would result from 

treated discharges may result in minor changes to 

physical stream conditions.

Yellowstone River

The Yellowstone River receives the combined flows 

of all other watersheds in the Montana portion of the 

Powder River Basin. The Forsyth, Montana station is 

the upstream station which receives no contribution 

from Wyoming discharges, but will receive some 

Montana CBNG discharge. The Sidney, Montana 

station is the downstream station and it will receive 

discharges from all Montana Powder River Basin 

wells and the approximately 21,391 CBNG wells 

from the Wyoming portion of the Powder River 

Basin under Alternative F. The cumulative impact at 

the Sidney station, however, is expected to be less 

under this alternative than under Alternative E. The 

phased development plan of this alternative will 

space out the drilling and production of wells so that 
CHAPTER 4

Hydrological Resources

4-127

the maximum development will not occur until year 

12 rather than year six under Alternative E. Because 

development is extended out over a longer time 

period, the maximum development level is less under 

Alternative F although this peak development level 

will extend over more time than under Alternative E.

The Yellowstone at the Sidney gauging station will 

be impacted by a maximum number of wells during 

year 12 when Montana CBNG wells are forecast to 

produce 34,961 gpm of water. This is approximately 

79.5 percent of the 43,989 gpm forecast for year six

under Alternative E. Effects to the Yellowstone at 

Sidney are predicted to be slightly less than effects 

under Alternative E in terms of both EC and SAR, 

although in reality these slight differences will likely 

be unnoticeable. Although some discernable surface 

water effects may be detected at the Sidney station, 

beneficial uses would not be reduced under 

Alternative F.

Summary of Surface Water Impacts

Impacts to surface water under this alternative will be 

less than under Alternative E. 

Surface water quality in some watersheds would be 

slightly degraded under Alternative F; however, 

downstream uses would not be diminished. Surface 

water flow would be moderately increased causing 

some localized riparian erosion, as well as locally 

increased sedimentation. There would not be 

anticipated impacts to beneficial uses under this 

alternative since MPDES permits would be required 

prior to discharge. 

Abandonment

Impacts to water resources due to abandonment 

operations would be similar to impacts under 

Alternatives B through E. When the estimated 

16,403 CBNG production wells are abandoned over

the 20-year project life, 33,000 acres of soil would be 

disturbed and reclaimed. This disturbed soil would be 

vulnerable to erosion and the resulting suspended 

material could be washed into adjacent surface waters 

unless mitigating measures are employed. The 

implementation of BMPs would reduce soil erosion 

until groundcover and original conditions are 

restored. 

Crow Reservation

Surface water effects on Crow Tribal Lands under 

Alternative F would be less than those effects noted 

in Alternative E. The peak volume of water 

discharged to the Little Bighorn River would be 

reduced and the water would need to be treated prior 

to discharge. Groundwater effects within the 

reservation boundary would be identified and 

controlled by monitoring and production restrictions. 

Any proposed federal CBNG development within 

5 miles of the reservation boundary would be 

required to conduct groundwater modeling to 

determine if there is the potential to impact tribal 

groundwater. If the potential exists monitoring of the 

produced coal seams will be required. The 

monitoring would track drawdown of aquifers from 

CBNG production on federal leases outside the 

reservation boundary. If drawdown is detected, the 

production rate of CBNG wells on federal leases 

could be restricted, or wells could be shut in, until an 

agreement is reached between the operator and the 

tribe regarding how groundwater impacts will be 

mitigated. Mitigation measures would substantially 

reduce drawdown originating from federal mineral 

leases, but the potential still exists for CBNG wells 

on nearby state and private leases to drawdown 

groundwater within the reservation boundaries. 

Northern Cheyenne

Surface water quality effects to Northern Cheyenne 

Tribal Lands under Alternative F would be similar to 

those impacts noted in Alternatives A and E, since no 

additional direct discharge of untreated CBNG water 

is assumed to occur into the Tongue River or 

Rosebud Creek. Flows in the Tongue and Rosebud 

would be moderately increased due to the discharge 

of treated water. The beneficial use of the Tongue 

and Rosebud streams would be maintained under 

Alternative F. 

CBNG developments have the potential to impact 

groundwater resources under Northern Cheyenne 

Tribal Lands. Any proposed federal CBNG 

development within 5 miles of the reservation 

boundary would be required to conduct groundwater 

modeling to determine if there is the potential to 

impact tribal groundwater. If the potential exists, 

monitoring of the produced coal seams will be 

required. The monitoring would track drawdown of 

aquifers from CBNG production on federal leases 

outside the reservation boundary. If drawdown is

detected, the production rate of CBNG wells on 

federal leases could be restricted, or wells could be 

shut in, until an agreement is reached between the 

operator and the tribe regarding how groundwater 

impacts will be mitigated. Mitigation measures would 

substantially reduce drawdown originating from 

federal mineral leases, but the potential still exists for 

CBNG wells on nearby state and private leases to 

drawdown groundwater within the reservation 

boundaries. 
CHAPTER 4

Hydrological Resources

4-128

Conclusion

Effects of this alternative on groundwater will be the 

same as Alternative B, with the exception that if 

CBNG development is lessened or does not occur 

within crucial sage-grouse habitat then groundwater 

drawdown would be locally decreased around these 

habitat areas. Additionally, modeling and monitoring 

would be required within 5 miles of the reservations 

in order to protect tribal groundwater. The operator’s 

WMPs would result in increased beneficial use of 

produced CBNG water, estimated to total at least 

20 percent. 

Cumulative Impacts to Montana watersheds due 

Wyoming CBNG discharge, coal mines and the 

Tongue River Railroad would be the same under this 

alternative as under Alternative A.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 

Anticipated impacts under this alternative include 

slight alteration of surface water quality, without 

diminishing downstream use. MPDES permits will be 

required prior to the discharge of any CBNG water 

(treated or untreated). The Montana BER standards 

are not anticipated to be exceeded and the WDEQ has 

modified its process to ensure numerical surface 

water standards are not exceeded at the stateline. As 

such, beneficial uses of surface waters will not be 

impacted.

Conditions placed on development within crucial 

sage-grouse habitat may result in a decreased 

quantity of CBNG produced water potentially being 

discharged; primarily to the Upper Tongue watershed 

and to a lesser degree the Lower Tongue and Middle 

Powder River watersheds. 

Alternative G—Phased Development 

Multiple Screens (Low Range)

Under this alternative, phased development would 

occur, but only 35 percent of the wells predicted for 

Alternative F would be drilled over the 23-year life of 

the resource. Maximum development is forecast to 

only involve 6,470 APDs and 5,823 CBNG wells. 

Water produced from CBNG wells could be managed 

similarly to that in Alternative F by emphasizing 

beneficial use of CBNG water while assuring that

MPDES requirements are met. The distribution of 

wells under Alternative G is forecast by applying the 

35 percent factor to each of the watersheds referred to 

under Alternative F. 

Under Alternative G surface discharge of untreated 

CBNG water in any watershed is limited to 10

percent of the 7Q10 value. This limit would apply to 

intermittent and ephemeral tributaries as well as main 

stems. For watershed totals see Table 4-55. If 

untreated discharge from Wyoming CBNG were

forecast to be greater than this limit, no untreated

water would be discharged from federal CBNG wells 

in the Montana portion of the watershed. If preexisting federal, state and private CBNG wells 

accounted for more than the untreated discharge 

limit, there could be no additional untreated 

discharge from federal CBNG wells. This analysis 

threshold would not be a limiting factor at this time 

since EC and SAR have been determined by the 

Montana BER to be harmful parameters which are 

regulated by the non-degradation rules. Since 

ambient water quality is greater than 40 percent of 

the standards in all watersheds, no untreated CBNG 

discharge would be allowed in Montana.

A WMP would be required prior to any exploration 

or production, listing the manner in which forecasted

produced water would be managed. Water 

management options other than untreated discharge 

may include beneficial use, injection, or treatment 

and discharge or any other properly permitted water 

management option. MPDES requirements must be

met prior to any discharges (treated or untreated). 

The WMP must address both site-specific conditions 

and cumulative effects of proposed water 

management methods. The plan would address the 

proposed water management practices and their 

effects on soil, water, vegetation, wildlife, stream 

channel stability and any other resources reasonably 

expected to be impacted by the actions. The WMP 

would be submitted in conjunction with PODs and

would need to be approved prior to or concurrent 

with the approval of any APDs.

Exploration

The volume of water generated by the testing of 

CBNG exploration wells would be stored in tanks or 

lined impoundments to be disposed of under the 

appropriate permits. 

Impacts from exploration would be similar to those 

discussed under alternative B.

Production

Water would be produced by each of the 

5,853 CBNG wells expected to be developed in the 
CHAPTER 4

Hydrological Resources

4-129

CBNG emphasis area; 35 percent of the number of 

wells forecast under Alternative G. Water will be 

managed by a number of options available to the 

operator. Because actual management practices are 

yet to be defined as far as the level of beneficial use 

and alternate water management practices (e.g., 

surface discharge), Alternative G, like Alternative F, 

assumes 20 percent will be used beneficially. The 

remainder of the water is assumed to be managed as 

in Alternative F discussed above except that the total 

volume to be managed would be only 35 percent of 

the volume forecast under Alternative F. 

Impacts from impoundments would be similar to 

those described under Alternative A.

Impacts on groundwater under this alternative would 

be similar to Alternative B in that drawdown is 

anticipated to extend 4-5 miles from CBNG fields 

after 20 years; however there would be fewer CBNG 

fields that drawdown would extend from. As 

discussed under impacts common to all alternatives, 

drawdown from CBNG could cause wells and springs 

which obtain their water from the developed coal 

seams to have reduced yields. It is anticipated 

requirements for water mitigation agreements under 

MCA 82-11-175 and the protections provided by 

MCA 75-15-9, will mitigate these drawdown-related 

impacts. 

Surface Water Analysis 

The analyses that follow address the watersheds 

within the Montana portion of the Powder River

Basin. Although other watersheds may be impacted 

around the state as a result of CBNG development, 

the Powder River Basin is the area most likely to 

experience CBNG activity. The Alternative G 

management option would maintain the beneficial 

uses of existing surface water resources in the 

Montana portion of the Powder River Basin. The 

number of APDs is listed for each watershed in Table 

4-2. Under this alternative the MDEQ’s nondegradation analysis thresholds for EC, SAR and 

Flow would apply to discharges in Montana, while 

Wyoming development would operate under their 

Alternative 2A. The 10 percent of 7Q10 untreated 

discharge threshold is maintained for this alternative; 

however it would not be an issue unless either EC or 

SAR were determined to be non-harmful parameters 

since new untreated discharges would not be allowed 

in Montana due to non-degradation standards. 

Therefore the 10 percent of 7Q10 untreated discharge 

threshold is not a part of this analysis, but rather 

provides an additional level of assurance due to the 

transitional nature of CBNG rules in Montana at this 

time. Treated discharges will be to ambient water 

quality. 

For analysis purposes the same process for assuming 

water management practices as outlined for 

Alternative F would also be used under Alternative 

G. This split is for analysis purposes only and is in no 

way intended to limit properly permitted water 

management options.

Tongue River

The Tongue River could be impacted by current and 

future CBNG development in both the Wyoming and 

Montana portions of the Powder River Basin. 

No additional untreated Montana CBNG surface 

discharge to the Tongue would be assumed under this 

alternative. One existing permit allows for 1,600 to 

2,500 gpm of untreated CBNG discharge from up to 

15 locations. Therefore, the surface water quality 

impacts will be similar to those listed under 

Alternative E. 

The remainder of the water produced in the Tongue 

River watershed is assumed to be treated and 

discharged; however other properly permitted 

managed water management practices would also be 

allowed. The disturbance associated with these water 

management activities would be approximately 35

percent of that estimated under Alternative E. 

The Tongue River is an important source of irrigation 

water in the Powder River Basin. The existing 

permits are anticipated to cause an unnoticeable 

amount of alteration in water quality and there would 

not be anticipated impacts to beneficial uses under 

this alternative since standards would not be 

exceeded. Any future MPDES permits for untreated 

discharge would require an authorization to degrade. 

Moderate increases in flow would occur as a result of 

treated discharges; however these increases would be 

less than the 40 percent MMM analysis threshold. 

These moderate increases in flow may result in slight 

changes to physical stream conditions. 

Little Bighorn and Bighorn Rivers

The Bighorn River and its tributary, the Little 

Bighorn, are not expected to be affected by Wyoming 

CBNG development, but are expected to be affected 

by CBNG wells on Indian lands as well as federal, 

state and private lands in Montana. Only 35 percent

of APDs and CBNG wells are expected in this 

watershed as under Alternative F. This volume of 

discharge is anticipated to only minimally affect 

water quality and resultant water quality would be 

between that calculated for Alternatives A and F. As 
CHAPTER 4

Hydrological Resources

4-130

such there would be no degradation of beneficial 

uses. The disturbance associated with these water 

management activities would be approximately 35

percent of that estimated under Alternative E.

The slight increases in flow that would result from 

this Alternative would result in unnoticeable changes 

to physical stream condition.

Rosebud Creek

Rosebud Creek is not expected to be affected by 

Wyoming CBNG wells and because Rosebud Creek 

contains such high quality water at such low flow 

rates, there is expected to be no untreated discharge 

of Montana CBNG water into Rosebud Creek under 

Alternative G; however there would be limited 

treated discharge. The 40 percent MMM analysis 

threshold would limit discharges in this watershed 

therefore impacts would be the same as Alternative F. 

The treated discharges would not degrade beneficial

uses. Other management practices such as injection, 

infiltration, beneficial use and evaporation will need 

to be utilized. The disturbance associated with these 

water management activities would be approximately 

35 percent of that estimated under Alternative E.

The moderate increases in flow caused by these 

discharges may result in minor changes to physical 

stream conditions.

Little Powder River

The Little Powder watershed is the site of CBNG 

development in Wyoming but the most prospective 

portion of the Fort Union Formation (the Tongue 

River Member) is sparsely present under this 

watershed in Montana. Because of the distribution of 

the Fort Union, little CBNG exploration and 

production is expected to occur in the Montana 

portion of the watershed. The quality of the Little 

Powder River exceeds the numerical standards of the 

MDEQ and it is an intermittent stream (7Q10=0).

Therefore, no untreated discharges are expected 

under Alternative G. As such, the resultant water 

quality would be the same as Alternative A and there 

would be no degradation of beneficial uses. Other 

management practices such as injection, infiltration, 

beneficial use and evaporation will need to be 

utilized. The disturbance associated with these water 

management activities would be approximately 35

percent of that estimated under Alternative E.

The slight increases in flow which would result from 

treated discharges may result in minor changes to 

physical stream conditions. 

Powder River

Alternative G assumes none of the produced CBNG 

water would be discharged under this alternative

since the allowable discharge (40 percent MMM) 

would be used up in Wyoming. The impacts to 

surface water quality under Alternative G (from 

Wyoming and Montana) will be less than those 

forecast under Alternative A due to the development 

of surface water quality standards which are 

enforceable at the stateline. Other management 

practices such as injection, infiltration, beneficial use

and evaporation will need to be utilized. The 

disturbance associated with these water management 

activities would be approximately 35 percent of that 

estimated under Alternative E.

The increases in flow which would result from 

Wyoming discharges may result in changes to 

physical stream conditions. 

Mizpah Creek

Impacts to surface water quality is expected to be the 

same under Alternative G as under Alternative A, 

since no untreated CBNG produced water could be 

discharged; beneficial uses would not be reduced.

Other management practices such as injection, 

infiltration, beneficial use and evaporation will need 

to be utilized. The disturbance associated with these 

water management activities would be approximately 

35 percent of that estimated under Alternative E.

The slight increases in flow which would result from 

treated discharges may result in minor changes to 

physical stream conditions. 

Yellowstone River

The Yellowstone River receives the combined flows 

of all the other watersheds in the Montana portion of 

the Powder River Basin. The Forsyth station is the 

upstream station which receives no contribution from 

Wyoming discharges, but will receive some MT 

CBNG discharge. The Sidney station is the 

downstream station and it will receive discharges 

from all 5,823 Montana Powder River Basin wells 

and approximately 21,391 CBNG wells from the 

Wyoming portion of the Powder River Basin under 

Alternative G. The effects to the Yellowstone River 

would be somewhat less than those indicated for 

Alternative F. Beneficial uses would not be reduced 

under Alternative G. 

The slight increases in flow that would result from 

this Alternative would result in unnoticeable changes 

to physical stream condition.
CHAPTER 4

Hydrological Resources

4-131

Summary of Surface Water Impacts

Surface water quality in some watersheds would be 

slightly reduced; however, downstream uses would 

not be diminished. Surface water flow would be 

slightly increased, potentially causing some riparian 

erosion, as well as increased sedimentation. Effects 

would be similar to, but somewhat less than under 

Alternative F.

Abandonment

Impacts to water resources due to abandonment 

operations under Alternative G would be 35 percent

of the impacts under Alternative F. When the 

estimated 5,823 CBNG production wells are 

abandoned over the 23-year resource life, an 

estimated 11,550 acres of soil would be disturbed and 

reclaimed. This disturbed soil would be vulnerable to 

erosion and the resulting suspended material could be 

washed into adjacent surface waters unless 

appropriate mitigating measures are employed. The 

implementation of various suitable mitigating 

measures would reduce soil erosion until 

groundcover and original conditions are restored. 

Crow Reservation

Surface water effects on Crow Tribal Lands under 

Alternative G would be similar to those effects noted 

in Alternative F, except the peak volume of water 

discharged to the Little Bighorn River would be 

reduced. Groundwater effects within the reservation 

boundary would be identified and controlled by 

monitoring and production restrictions. Any proposed 

federal CBNG development within 5 miles of the 

reservation boundary would be required to conduct 

groundwater modeling to determine if there is the 

potential to impact tribal groundwater. If the potential 

exists to impact tribal groundwater, monitoring of the 

produced coal seams will be required. The 

monitoring would track drawdown of aquifers from 

CBNG production on federal leases outside the 

reservation boundary. If drawdown is detected, the 

production rate of CBNG wells on federal leases 

could be restricted, or wells could be shut in, until an 

agreement is reached between the operator and the 

tribe regarding how groundwater impacts will be 

mitigated. Mitigation measures would substantially 

reduce drawdown originating from federal mineral 

leases, but the potential still exists for CBNG wells 

on nearby state and private leases to drawdown 

groundwater within the reservation boundaries. 

Northern Cheyenne

Surface water quality effects to Northern Cheyenne 

Tribal Lands under Alternative G would be similar to 

those impacts noted in Alternative A, since no 

additional direct discharge of CBNG water is 

assumed to occur into the Tongue River or Rosebud 

Creek. The volume of flow in the Tongue and 

Rosebud would increase due to treated discharges. In 

the Tongue this increase would be less than projected 

under Alterative F. In the Rosebud the increase 

would be the same as alternative F. Slight alteration

of the Tongue River would occur as a result of 

existing permits, however the beneficial uses of the 

Tongue and Rosebud would be maintained. 

CBNG developments have the potential to impact 

groundwater resources under Northern Cheyenne 

Tribal Lands. Any proposed federal CBNG 

development within 5 miles of the reservation 

boundary would be required to conduct groundwater 

modeling to determine if there is the potential to 

impact tribal groundwater. If the potential exists to 

impact tribal groundwater, monitoring of the 

produced coal seams will be required. The 

monitoring would track drawdown of aquifers from 

CBNG production on federal leases outside the 

reservation boundary. If drawdown is detected, the 

production rate of CBNG wells on federal leases 

could be restricted, or wells could be shut in, until an 

agreement is reached between the operator and the 

tribe regarding how groundwater impacts will be 

mitigated. Mitigation measures would substantially 

reduce drawdown originating from federal mineral 

leases, but the potential still exists for CBNG wells 

on nearby state and private leases to drawdown 

groundwater within the reservation boundaries. 

Conclusion

Similar to the other alternatives, drawdown from 

CBNG developments would be expected to extend 

4 to 5 miles from CBNG fields; however, there 

would be fewer fields to exhibit drawdown. 

Cumulative Impacts to Montana watersheds due to 

Wyoming CBNG discharge, coal mines and the 

Tongue River Railroad would be the same under this 

alternative as under Alternative A.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated the requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 
CHAPTER 4

Hydrological Resources

4-132

Minor effects on shallow groundwater quality from 

impoundment infiltration and surface discharge of 

some untreated production water may also occur as 

discussed under alternatives A and B. The operator’s 

WMPs would result in increased beneficial use of 

produced CBNG water, estimated to total at least 

20 percent. 

Surface water effects under Alternative G would be 

the same as, or less than the effects of Alternative F 

in the individual watersheds. Even where discharge is 

an available option operators may choose other 

options when managing their CBNG water with 

simultaneous reductions in the volume of surface 

discharge. Consultation with state and federal 

agencies charged with managing Wyoming’s 

resources have allowed close cooperation and 

improved estimation of likely impacts to the surface 

waters of Montana from CBNG and other activities 

under this alternative. The cumulative impacts to 

surface water and groundwater further depend upon 

MDEQ standards. Anticipated impacts under this 

alternative include slight alteration of surface water 

quality, without diminishing downstream use. The 

slight increases in flow which would result from

discharges may result in minor changes to physical 

stream conditions. 

Alternative H—Preferred Alternative - 

Multiple Screens

Under this alternative, CBNG development is 

expected in approximately the same total numbers 

predicted for Alternative F although development 

rate is somewhat different due to there being no 

annual or watershed limit. Water produced from 

CBNG wells could be managed similarly to that in 

Alternative F by emphasizing beneficial use of 

CBNG water while assuring that MPDES 

requirements are met. The distribution of wells under 

the Preferred Alternative is forecast by modifying the 

forecast development within the various watersheds 

referred to under Alternative F. In the Preferred 

Alternative, development of the CBNG resource 

under each watershed is expected to occur in a more 

discrete, more rapid manner rather than the drilling 

being drawn out within each watershed. Total wells 

in the watersheds and total wells in the Planning Area

are forecast to be approximately the same. 

If untreated discharges within a watershed exceed 

10% of the 7Q10 the BLM would coordinate with 

MDEQ to prepare a surface water monitoring report. 

If the results of this analysis indicate CBNG 

discharges have the potential to cause exceedances of 

surface water quality standards, the BLM would 

coordinate with MDEQ to develop appropriate 

mitigation measures to prevent exceedances. 

Additionally, no future untreated discharge of CBNG 

water would be allowed from federal wells unless the 

regional surface water monitoring stations above and 

below the proposed discharge are active.

If CBNG discharges are causing surface water quality 

standards to be exceeded no additional CBNG 

discharges would be allowed from federal wells 

upstream of the exceedance. Previously approved

water management plans may also be modified. 

Water quality thresholds and the surface water 

monitoring requirements are detailed in the 

Monitoring Appendix. 

A WMP would be required prior to any exploration 

or production, listing the manner in which forecast 

produced water would be managed. Water 

management options other than untreated discharge 

may include beneficial use, injection, treatment and 

discharge or any other properly permitted water 

management option. MPDES requirements must be 

met prior to any discharges (treated or untreated). 

The WMP must address both site-specific conditions 

and cumulative effects of proposed water 

management methods. The plan would address the 

proposed water management practices and their 

effects on soil, water, vegetation, wildlife, stream 

channel stability and any other resources reasonably 

expected to be impacted by the actions. The WMP 

would be submitted in conjunction with PODs and

would need to be approved prior to or concurrent 

with the approval of any APDs.

Exploration

The volume of water generated by the testing of 

CBNG exploration wells would be stored in tanks or 

lined impoundments to be disposed of under the 

appropriate permits. 

Impacts from exploration would be similar to those 

discussed under alternative B.

Production

Water would be produced by each of the 

approximately 16,404 CBNG wells expected to be 

developed in the CBNG emphasis area under the 

Preferred Alternative. Water will be managed by a 

number of options available to the operator. Because 

actual management practices are yet to be defined as 

far as the level of beneficial use and alternate water 

management practices (e.g., surface discharge), the 

Preferred Alternative, like Alternative F, assumes 20

percent will be used beneficially. The remainder of 

the water is assumed to be managed as in Alternative 

F discussed above. 
CHAPTER 4

Hydrological Resources

4-133

Impacts from impoundments would be similar to 

those described under Alternative A.

Impacts on groundwater under this alternative would 

be the same as in Alternative B with the exception 

that groundwater drawdown would be somewhat 

reduced if development does not occur or is lessened 

within crucial sage-grouse habitat areas. As discussed 

under impacts common to all alternatives, drawdown 

from CBNG could cause wells and springs which 

obtain their water from the developed coal seams to 

have reduced yields. It is anticipated the requirements 

for water mitigation agreements under MCA 82-11-

175 and the protections provided by MCA 75-15-9, 

will mitigate these drawdown-related impacts. 

Surface Water Analysis 

This analysis will occur following the same rules as 

Alternative F, except in the event the 10 percent of 

7Q10 untreated discharge limit became a factor, there 

would be the option to wave this criterion if the 

monitoring identified by the IWG were in place. The 

analyses that follow address the watersheds within 

the Montana portion of the Powder River Basin. 

Although other watersheds may be impacted around 

the state as a result of CBNG development, the 

Powder River Basin is the area most likely to 

experience CBNG activity. The Preferred Alternative

management option would maintain the beneficial 

uses of existing surface water resources in the 

Montana portion of the Powder River Basin. 

Tongue River

The Tongue River could be impacted by current and 

future CBNG development in both the Wyoming and 

Montana portions of the Powder River Basin. 

No additional untreated Montana CBNG surface 

discharge to the Tongue would be assumed under this 

alternative. One existing permit allows for 1,600 to 

2,500 gpm of untreated CBNG discharge from up to 

15 locations. Therefore, the surface water quality 

impacts will be similar to those listed under 

Alternative E. 

The remainder of the water produced in the Tongue 

River watershed is assumed to be treated and 

discharged; however other properly permitted 

managed water management practices would also be 

allowed. The disturbance associated with these water 

management activities would be comparable to that 

estimated under Alternative E.

The Tongue River is an important source of irrigation 

water in the Powder River Basin. The existing 

permits are anticipated to cause an unnoticeable 

amount of alteration in water quality and there would 

not be anticipated impacts to beneficial uses under 

this alternative since standards would not be 

exceeded. Any future MPDES permits for untreated 

discharge would require an authorization to degrade. 

Additionally, pollutants including salinity, total 

dissolved solids and nutrients also are frequently 

associated with agricultural operations.

Moderate increases in flow would occur as a result of 

treated discharges; however these increases would be 

less than the 40 percent MMM analysis threshold. 

These moderate increases in flow may result in slight 

changes to physical stream conditions. 

Little Bighorn and Bighorn Rivers

The Bighorn River and its tributary, the Little 

Bighorn, are not expected to be affected by Wyoming 

CBNG development, but are expected to be affected 

by CBNG wells on state, private and federal lands in 

Montana under the Preferred Alternative. 

The resultant surface water impacts to the Bighorn 

rivers would be between those identified for 

Alternatives D and E since untreated discharge is 

anticipated under the Preferred Alternative only on 

the Crow Reservation. Actual CBNG discharge 

volumes will be dependent on site-specific conditions 

and the approval of a WMP. In order to be approved 

the WMP would need to show how the produced 

water could be managed without impacting beneficial 

uses. MPDES permits will be required prior to the 

approval of WMPs. As such, there would be no 

impact to beneficial uses under this alternative.

The slight increases in flow that would result from 

this Alternative would result in minor changes to 

physical stream condition. 

Rosebud Creek

Rosebud Creek is not expected to be affected by 

Wyoming CBNG wells and because Rosebud Creek 

contains such high quality water at such low flow 

rates, there is expected to be no untreated discharge

of Montana CBNG water into Rosebud Creek under 

the Preferred Alternative and impacts would be the 

same as Alternative F. As there would be no 

untreated discharge under this alternative there would 

be no alteration of beneficial uses. 

The moderate increases in flow caused by these 

discharges may result in minor changes to physical 

stream conditions.
CHAPTER 4

Hydrological Resources

4-134

Little Powder River

The Little Powder watershed is the site of CBNG 

development in Wyoming but the most prospective 

portion of the Fort Union Formation (the Tongue 

River Member) is sparsely present under this 

watershed in Montana. Because of the distribution of 

the Fort Union, little CBNG exploration and 

production is expected to occur in the Montana 

portion of the watershed. The quality of the Little 

Powder River exceeds the numerical standards of the 

MDEQ and it is an intermittent stream (that is, 

7Q10=0). Therefore, no treated or untreated 

discharges are expected under the Preferred 

Alternative. Impacts would be the same as 

Alternative F and there would be no degradation of 

beneficial uses. 

The moderate increases in flow caused by treated

discharges may result in minor changes to physical 

stream conditions.

Powder River

The Preferred Alternative assumes 100 percent of 

potential CBNG discharge (40 percent MMM) would 

be taken up by Wyoming development, therefore 

none of the water produced in Montana would be 

discharged either in untreated or treated form under 

this alternative. The impacts to surface water quality 

under the Preferred Alternative will the same as

under Alternative F. 

Mizpah Creek

Impacts to surface waters are expected to be the same 

under the Preferred Alternative as under 

Alternative F since no untreated CBNG produced 

water could be discharged under these alternatives

and treated discharges would be limited by the 40

percent MMM analysis threshold. Beneficial uses 

would not be reduced. 

The moderate increases in flow caused by these 

discharges may result in minor changes to physical 

stream conditions.

Yellowstone River

The Yellowstone River receives the combined flows 

of all other watersheds in the Montana portion of the 

Powder River Basin. The Forsyth station is the 

upstream station which receives no contribution from 

Wyoming discharges, but will receive some MT 

CBNG discharge. The Sidney station is the 

downstream station and it will receive discharges 

from all Montana Powder River Basin wells and the 

approximately 21,391 CBNG wells from the 

Wyoming portion of the Powder River Basin under 

the Preferred Alternative. CBNG discharges to these 

streams would be a combination of treated and 

untreated water. The cumulative impact at the Sidney 

station, however, is expected to be less under this 

alternative than under Alternative E. 

The Yellowstone at the Sidney gauging station will 

be impacted by a maximum number of wells during 

year 12 when Montana CBNG wells are forecast to 

produce 34,961 gpm of water. Effects to the 

Yellowstone under the Preferred Alternative are 

expected to be approximately the same as those under 

Alternative F. Although some discernable surface 

water effects may be detected at the Sidney station, 

beneficial uses would not be reduced under the 

Preferred Alternative. 

The slight increases in flow that would result from 

this Alternative would result in unnoticeable changes 

to physical stream condition.

Summary of Surface Water Impacts

Impacts to surface water under this alternative will be 

essentially the same as under Alternative F. 

Surface water quality in some watersheds would be 

slightly altered due to existing permits and CBNG 

development in Wyoming; however, downstream 

uses would not be diminished. Surface water flow 

would be moderately increased causing some 

localized riparian erosion, as well as locally increased 

sedimentation. 

Abandonment

Impacts to water resources due to abandonment 

operations would be similar to impacts under 

Alternative E. When the estimated 16,403 CBNG 

production wells are abandoned over the 20-year 

project life, 33,000 acres of soil would be disturbed 

and reclaimed. This disturbed soil would be 

vulnerable to erosion and the resulting suspended 

material could be washed into adjacent surface waters 

unless mitigating measures are employed. The 

implementation of BMPs would reduce soil erosion 

until groundcover and original conditions are 

restored. 

Crow Reservation

Surface water effects on Crow Tribal Lands under the 

Preferred Alternative would be similar to those 

effects noted in Alternative F, except that the peak 

volume of water discharged to the Little Bighorn 

River would be reduced. Groundwater effects within 

the reservation boundary would be identified and 

controlled by monitoring and production restrictions. 

Any proposed federal CBNG development within 
CHAPTER 4

Hydrological Resources

4-135

5 miles of the reservation boundary would be 

required to conduct groundwater modeling to 

determine if there is the potential to impact tribal 

groundwater. If the potential exists, monitoring of the 

produced coal seams will be required. The 

monitoring would track drawdown of aquifers 

resulting from CBNG production on federal leases 

outside the reservation boundary. If drawdown is 

detected, the production rate of CBNG wells on 

federal leases could be restricted, or wells could be 

shut in, until an agreement is reached between the 

operator and the tribe regarding how groundwater 

impacts will be mitigated. Mitigation measures would 

substantially reduce drawdown originating from 

federal mineral leases, but the potential still exists for 

CBNG wells on nearby state and private leases to 

drawdown groundwater within the reservation 

boundaries. 

Northern Cheyenne

Surface water effects to Northern Cheyenne Tribal 

Lands under the Preferred Alternative would be 

similar to those impacts noted in Alternative F, since 

no additional direct discharge of CBNG water is 

assumed to occur into the Tongue River or Rosebud 

Creek. The beneficial use of the Tongue and Rosebud 

streams would be maintained under the Preferred 

Alternative. 

CBNG developments have the potential to impact 

groundwater resources under Northern Cheyenne 

Tribal Lands. Any proposed federal CBNG 

development within 5 miles of the reservation 

boundary would be required to conduct groundwater 

modeling to determine if there is the potential to 

impact tribal groundwater. If the potential exists, 

monitoring of the produced coal seams will be 

required. The monitoring would track drawdown of 

aquifers from CBNG production on federal leases 

outside the reservation boundary. If drawdown is 

detected, the production rate of CBNG wells on 

federal leases could be restricted, or wells could be 

shut in, until an agreement is reached between the 

operator and the tribe regarding how groundwater 

impacts will be mitigated. Mitigation measures would 

substantially reduce drawdown originating from 

federal mineral leases, but the potential still exists for 

CBNG wells on nearby state and private leases to 

drawdown groundwater within the reservation 

boundaries. 

Conclusion

Effects of this alternative on groundwater will be the 

same as Alternative B with the exception that if 

CBNG development is lessened or does not occur 

within crucial sage-grouse habitat then groundwater 

drawdown would be locally decreased around these 

habitat areas. The operator’s WMPs would result in 

increased beneficial use of produced CBNG water, 

estimated to total at least 20 percent. 

Cumulative impacts to Montana watersheds due 

Wyoming CBNG discharge, coal mines and the 

Tongue River Railroad would be the same under this 

Preferred Alternative as under Alternative A.

As discussed under impacts common to all 

alternatives, drawdown from CBNG could cause 

wells and springs which obtain their water from the 

developed coal seams to have reduced yields. It is 

anticipated requirements for water mitigation

agreements under MCA 82-11-175 and the 

protections provided by MCA 75-15-9, will mitigate 

these drawdown-related impacts. 

Anticipated impacts under this alternative include 

slight alteration of surface water quality due to 

existing permits in Montana as well as current and 

forecast Wyoming CBNG development; however 

downstream uses will not be diminished. MPDES 

permits will be required prior to the discharge of any 

CBNG water (treated or untreated). It is not 

anticipated MDEQ would allow any untreated 

discharges due to the non-degradation rules for EC 

and SAR. The Montana BER standards are not 

anticipated to be exceeded. As such, beneficial uses 

of surface waters will not be impacted.
CHAPTER 4

Indian Trust and Native American Concerns

4-136

Indian Trust and Native American 

Concerns

Indian Trust Assets

Indian Trust Assets (ITAs) are official interests in assets held in 

trust by the federal government for Indian tribes or individuals.

The U.S. Department of the Interior (DOI) Departmental 

Manual 303 DM 2 defines ITAs as lands, natural resources, 

money, or other assets held by the federal government in trust 

or that are restricted against alienation for Indian tribes and 

individual Indians.

Alternative A

No Action (Existing CBNG Management)

• No measurable impacts to Indian trust impacts would 

occur from the CBNG activities. 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Federal:

− No surface water quality impacts.

− Potential CBNG drainage, dependent on specific site 

conditions, delayed by buffer zone.

− Air Quality impacts to reservation PSD Class I 

areas.

− Visibility impacts.

− Potential cultural resource impacts to TCPs

• State:

− Groundwater drawdown inward from reservation 

boundaries.

− Potential CBNG drainage, dependent on specific site 

conditions, no delay due to adjacent development.

Alternative C

Emphasize CBNG Development

• Federal:

− Potential for surface water quality and quantity 

impacts.

− Potential CBNG drainage, same as Alternative B.

− Cultural Resource impacts same as B.

− Air quality and visibility impacts same as 

Alternative B.

• State:

− Groundwater drawdown same as Alternative B.

− Surface water quality and quantity impacts.

− Potential CBNG drainage, same as Alternative B.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Federal:

− Groundwater drawdown same as Alternative B.

− Surface water quality impacts reduced by source 

treatment, increased availability of surface waters 

for irrigation and other beneficial uses

− Increased surface water flow could in increase 

riparian erosion.

− Potential CBNG drainage, same as Alternative B.

− Cultural Resource impacts same as B.

− Air Quality and visibility impacts reduced.

• State:

− Groundwater drawdown same as Alternative B.

− Surface water quality impacts reduced.

− Potential CBNG drainage, same as Alternative B.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Federal:

− Effects from groundwater drawdown substantially 

reduced by resource protection protocols. Potential 

CBNG drainage mitigated or compensated.

− Surface water quality impacts reduced, with 

increased availability of surface waters for irrigation 

and other beneficial uses.

− Increased surface water flow could increase riparian 

erosion.

− Air Quality impacts mitigated through site specific 

permits and control measures.

• State:

− Groundwater drawdown potential on the 

reservations would be minimized. CBNG drainage 

minimized by state spacing. 

− Surface water quality protected.

Alternative F

Phased Development Multiple Screens (High Range)

• Federal:

− Potential effects from groundwater drawdown 

reduced by implementation of a 5-miles buffer zone. 

Potential CBNG drainage mitigated or eliminated.

− Surface water quality impacts reduced.

− Traditional cultural property (TCP) sites identified 

sooner through the use of block surveys and tribal

consultations.

− Air Quality impacts mitigated through site specific 

permits and control measures.

• State:

− Same as Alternative E

Alternative G

Phased Development Multiple Screens (Low Range)

• Federal:

− Potential impacts from alternative G would be 

similar to Alternative F except that they would be 

approximately 65 percent less due to the reduced 

number of APDs that are predicted to be issued. A 5-

mile buffer zone would still be implemented around 

the reservation boundaries to protect against CBNG 

drainage or groundwater drawdown

− Surface water quality impacts similar to Alternative 

F although reduced due to the decreased number of 

APDs that are predicted to be issued. 

− TCP site identified sooner through the use of block 

surveys and tribal consultations.

− Air Quality impacts mitigated through site specific 

permits and control measures.

• State:

Same as Alternatives E and F.
CHAPTER 4

Indian Trust and Native American Concerns

4-137

Alternative H

Preferred Alternative - Multiple Screens

• Federal:

− Potential effects from groundwater drawdown 

reduced by implementation of a 5-miles buffer zone. 

Potential CBNG drainage mitigated or eliminated.

− Surface water quality impacts reduced.

− TCP site identified sooner through the use of block 

surveys and tribal consultations.

− Air Quality impacts mitigated through site specific 

permits and control measures.

• State:

- Groundwater drawdown potential on the 

reservations would be minimized. CBNG drainage 

minimized by state spacing. Surface water quality 

protected.

Assumptions

The BLM's responsibilities include identifying and 

protecting tribal resources and trust assets from 

impacts resulting from BLM actions. The state does 

not have a trust responsibility similar to the federal 

governments. The 2-mile buffer zone around the 

reservations as called for in the management 

objectives for Alternatives B and D would only apply 

to federal leases. The 5-mile buffer zone around the 

reservations as called for in the management 

objectives for Alternatives F, G and H would only 

apply to federal leases.

Impacts From Management 

Common to All Alternatives

While the BLM would not have jurisdiction over 

Indian lands located on or off the reservation, the 

BLM would have a trust responsibility that 

encompasses oil and gas exploration. Indian Trust 

Assets (ITAs) would be managed following the DOI 

Secretarial Order 3215, Principles for the Discharge 

of the Secretary’s Trust Responsibility.

The conventional wells expected to be drilled on 

BLM-administered lands could impact adjacent 

reservation lands by draining tribal hydrocarbons or 

groundwater, or even by allowing produced water to 

impact surface water resources or soil. Drainage by 

adjacent wells is addressed by 43 CFR Part 3162.2-2, 

which instructs the BLM on steps to be taken to 

protect Indian landowners from drainage.

The number of conventional wells estimated for 

reservation development (12) coupled with the 

predicted wells (less than 25) adjacent to reservation 

lands; do not represent a measurable increase in 

development on or near the reservation for the next 

20 years. This level of development would not impact 

tribal hydrocarbons or effect groundwater resources. 

The direct land impacts from this small number of 

wells on reservation lands would be minor (less than 

75 total acres impacted) with regard to grazing lands, 

vegetation and biological resources.

Construction and maintenance of the Tongue River 

Railroad (TRR) route would not directly impact 

Indian reservation lands; however, emissions from 

trains could impact air quality over parts of the 

reservations. Because of the proximity of the 

approved TRR route, the two reservations and 

residents could be indirectly impacted by the 

construction activities and the train traffic. Impacts to 

Indian lands along the entire TRR extension route are 

described, in part, in the follow three reports: 

− Potential Cultural Effects on the Northern 

Cheyenne from the TRR Extension (Deaver 

and Tallbull 1991)

− Montana Department of Natural Resources 

Conservation, Tongue River Reservoir EIS

(Aaberg and Tallbull 1993, Peterson et al. 

1995)

− Draft Economic, Social, Cultural 

Supplement, Powder River I Regional EIS, 

(BLM 1989)

− TRR EIS (Surface Transportation Board 

2004)

In considering Native American concerns, any 

Surface Transportation Board decision during 

construction or operation of the TRR Extension 

would be subject to the mitigation set forth in the 

programmatic agreement as detailed in Chapter 

4.2.5.3 of the Supplemental EIS for the TRR 

Extension (STB 2004). 

Social and economic impacts identified by the 

Northern Cheyenne that are associated with the 

construction of the TRR center primarily on potential 

in-migration of Native and non-Native Americans in

search of construction related jobs. If the regional 

population was to increase, there are fears that nonNative Americans would settle in reservation 

communities if off-reservation housing facilities 

prove inadequate, leading to potential commensurate 

increase of contact with non-Native Americans. This 

increased inter-racial contact could increase tribal 

member exposure to prejudice; intolerance; and 

divergent ideas, values and behaviors (ICC 1992). 
CHAPTER 4

Indian Trust and Native American Concerns

4-138

With regards to important wild plants, there are 

concerns that traditional gathering localities may be 

disturbed and access to these areas could be 

precluded by fencing erected along the route (ICC 

1992). 

As discussed earlier under Alternative C, the 

Absaloka Coal Mine could be encroached on by 

CBNG development but wells could not be drilled 

within permitted coal mining acres. The coal is held 

in trust for the Crow Tribe. 

Mitigation measures would help protect Northern 

Cheyenne tribal resources and off-reservation sites,

such as the Rosebud and Wolf Mountain Battlefields, 

known to be of special importance to the tribe. A 

discussion of these mitigation measures is presented 

in the Northern Cheyenne Mitigation Appendix. 

These mitigation and monitoring measures have been 

designed to help protect resources such as 

groundwater, CBNG, air quality, wildlife, vegetation

and off-reservation cultural resources of special 

interest to the tribe. 

The Northern Cheyenne Tribe also has offreservation properties held in trust that consist of two, 

tracts of land, approximately 160 acres each, in the 

vicinity of the Tongue River Reservoir. The tribe also 

acquired off-reservation surface estate consisting of 

the Moreland Ranch property. The mineral estate for 

the Moreland Ranch property is owned by the 

Consolidated Coal Company and could be subject to 

development; however it is currently not leased. The 

BLM would consult with the tribe to determine what 

mitigation measures are needed to protect the surface 

use of the ranch. Tribal buffalo herds are pastured at 

the Moreland Ranch property.

With regard to off-reservation TCPs and cultural 

artifacts the BLM has implemented a cultural survey 

requirement for the majority of CBNG lands to be 

developed under each POD. The use of these “block 

surveys” coupled with tribal consultation 

requirements has demonstrated the ability to identify 

the majority of sites that could be affected and reduce 

the potential impacts associated with developing 

CBNG in the vicinity of cultural resources.

Furthermore, on January 12, 2006, the BLM Montana 

State Office issued additional cultural resource 

requirements for oil and gas operations in Montana 

and the Dakotas. These requirements are intended for 

both oil and gas operators and cultural resource 

consultants hired by oil and gas operators. They 

supplement the Guidelines for Identifying Cultural 

Resources H-8110-1 (the handbook) which remains 

the basic guidance for cultural resource work 

completed for BLM undertakings. Notice to Lessees, 

NTL-MSO-1-85, provides guidelines to operators 

when they are required to conduct cultural resource 

inventories. The NTL establishes the minimum 

survey area of 10 acres centered on each proposed 

well plus the access road, pipeline and ancillary areas 

subject to surface disturbance. Washington Office 

Instruction Memorandum (IM) No. 2003-147 (BLM 

2003c) recommends block surveys ranging from 40 

acres for individual wells to entire lease or full field 

development areas for large-scale projects to improve 

the APD process. Block surveys offer many 

advantages including reducing the probability that 

multiple surveys will be required to site a single

project. Additionally, operators are encouraged to 

complete cultural resource surveys prior to the onsite 

inspection. This will allow the well location and/or 

access route to be sited prior to the onsite in order to 

avoid adverse effects on cultural resources and 

reduce the likelihood of having to change a location 

due to a cultural resource conflict discovered later in 

the APD review process.

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG

Management)

There would not be any impacts to measurable ITAs 

from the CBNG activities planned under this 

alternative.

This is based on the limited development scenario 

under this alternative, the known locations of 

production wells (CX Ranch) and the number of 

exploration wells. 

Conclusion

There would not be any impacts to ITAs from 

management decisions under Alternative A or from 

management practices common to all alternatives. 

Cumulative effect impacts could result from the 

Absaloka Coal Mine and the production and 

discharge of CBNG production waters from 

Wyoming.

Mining activities at the 5,400-acre Absaloka Coal 

Mine facility located just north of the northeastern 

corner of the Crow Reservation has resulted in the 

irretrievable loss of the coal mined at approximately 

5 million tons per year and has removed or disturbed 

approximately 3,150 acres of topsoil. Additional 

impacts have occurred from the dewatering of the 

coal that lowered the surrounding groundwater by an 

estimated 75 feet (Wheaton and Van Voast 1998). 
CHAPTER 4

Indian Trust and Native American Concerns

4-139

Finally, the surface water within the vicinity of the 

mine has undergone a reduction in quality, resulting 

in impacts on the local watercourses and subsequent 

fields using these waters as sources of irrigation.

Development of CBNG in Wyoming during the next 

20 years has the potential to impact the surface water, 

groundwater and methane resources of the Crow and 

Northern Cheyenne tribes. Drawdown of 

groundwater levels is an unavoidable impact from 

CBNG development. Increased groundwater 

drawdown would be experienced in coal seam 

aquifers along the southeastern border of the Crow 

Reservation adjacent to and up to 5 miles north of the 

Wyoming state line (Wheaton and Metesh 2001). The 

magnitude of impact to water wells and springs 

would depend on the location and number of CBNG

producing wells south of the state boundary. 

Depending upon their locations, natural springs and 

water wells on tribal lands could go dry.

Wyoming CBNG production could also drain 

methane from tribal mineral resources. As 

groundwater is drawn down and reservoir pressures 

decrease, methane is liberated from the coal matrix 

and becomes free to be produced or migrate. Twodimensional modeling (Crockett and Meyer 2001) 

suggests that drainage of methane could occur at 

distances more than 5 miles from a producing CBNG

field. Recent three-dimensional modeling suggests 

that the methane drainage effect is less than two

miles. This is based on the model results indicating 

that 80 feet of water would be drawn down at two

miles from the edge of a producing field (Wheaton 

and Metesh 2002). In either case, the Crow 

Reservation is adjacent to the Wyoming boundary 

and is close enough to be drained by CBNG wells 

that may be drilled in Wyoming.

Full-scale CBNG production in the Wyoming portion 

of the Powder River Basin would result in limited 

surface discharge and infiltration of produced water 

to streams that flow north into Montana. Expected 

levels of development would result in volumes of 

discharged water causing a slight increase in annual 

flow rates of the Powder, Little Powder and Tongue 

rivers. A corresponding slight alteration in the quality 

of surface water would also be felt downstream from 

these Wyoming discharges. The percent increase in 

flow volume would be greater during periods of lowflow. This alteration may require downstream users 

to implement minor management changes. Impacts to 

the Tongue River would be felt by the Northern 

Cheyenne and Crow members who use river water 

for irrigation. Detailed discussions regarding surface 

water quality and flow changes are presented in the 

Hydrologic Resources section of this chapter.

The Bighorn and Little Bighorn rivers carry high 

quality water from the Bighorn Mountains north into 

Montana. No CBNG wells in Wyoming or Montana 

would impact these rivers under Alternative A. 

Stream water quality and flow volume would remain 

unchanged. 

The Northern Cheyenne have a large reserved water 

right in the Tongue River Reservoir. That stored 

water represents a marketable commodity and if it 

were to experience even a slight decrease in quality, 

it would affect the tribes’ ability to market or use the 

water. Under this full-scale Wyoming development 

scenario, it is conceivable that the reservoir water 

quality could be slightly altered.

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Based on the development scenario presented in 

Alternative B and on the management objectives 

described under this alternative, potential impacts on 

ITAs include the drawdown of groundwater, 

alterations in surface water quality, air quality 

changes, potential social and cultural impacts, 

potential wildlife adaptation and the drainage of tribal

CBNG.

A 20 foot drawdown of the groundwater table within 

the vicinity of a producing Montana CBNG field has 

been modeled (3D) by the Montana Bureau of Mines 

and Geology (MBMG) at between 4 to 5 miles from 

the edge of production (Wheaton and Metesh 2002). 

Without site-specific information, it is impossible to 

predict the degree of drawdown to a neighboring 

aquifer. In the case of the Crow and Northern 

Cheyenne, it is conceivable that the reservations’ 

groundwater would be drawn down to some extent 

along the boundaries by both state and BLM-leased 

development. The drawdown of groundwater within 

the reservation could result in impacts on shallow 

stock and domestic wells and some surface springs. 

These impacts would reduce water pressure and in 

some cases could render the complete loss of water 

from a well or spring.

The recognition of a 2-mile buffer zone around the 

reservations would effectively reduce and delay the 

drawdown that would be experienced by the tribes in 

these areas from BLM leased mineral development. 

In the case of development on either private or state 

private lands, the state would not be subject to the 

same buffer zone restrictions and therefore, the 

drawdown could be generated earlier and be to a 

greater horizontal and vertical extent. The effect of 
CHAPTER 4

Indian Trust and Native American Concerns

4-140

these combined drawdowns would create a long-term 

impact to the groundwater level.

The alteration of surface water quality from the 

management objectives in this alternative is almost 

negligible because the alternative calls for the 

injection of all produced water and the storage of all 

waters generated during exploration well tests. 

However, the potential exists for localized, shortterm (less than 1 year) impacts from spills and 

ruptures associated with these water disposal 

methods. Undetected ruptures along water conduits

feeding injection wells also would impact soils and 

create erosion problems within the immediate 

vicinity. These impacts are not expected to reach 

reservation lands under this management objective. 

Only the spilled or released waters entering 

associated watersheds near the reservations would be 

affected.

Numerous social and cultural impacts have been 

predicted by Native Americans as a result of CBNG

development on adjacent private, state and federal 

minerals. These potential impacts include the lack of 

access to well-paying energy-related employment

contributing to the reduced annual Native American 

income; over-commitment of tribal revenues; 

population influx; abridged effectiveness of tribal

governments; stressed infrastructure and servicerelated capacity; altered social organization and 

social well-being perception; and the further 

influence of western culture resulting in changes to 

traditional belief and value systems.

Off-reservation cultural and paleontological artifacts 

also run the risk of being damaged or lost due to the 

increased access and land-disturbing activities 

associated with full-scale development. TCPs may be 

affected as development expands. These impacts 

would be minimized through survey and consultation 

with the tribes.

Wildlife would adapt to the CBNG development 

infrastructure in ways that could be interpreted as 

negative or positive. For example, depending on 

one’s perspective, big game migratory paths could 

shift resulting in greater opportunities for tribal 

outfitters and tribal hunters or diminished chances for 

euro-American outfitters and hunters. This scenario 

could result in reduced herd strength or increased 

susceptibility could also be viewed as a negative 

outcome or singularity. Given the various and 

complex perspectives, wildlife impacts need to be 

assessed on a case-by-case basis as individual CBNG

actions are reviewed.

CBNG development would threaten to drain methane 

resources under tribal lands in the Planning Area. 

Drainage of CBNG resources from Native American 

minerals is dependent upon local reservoir 

parameters. It is assumed that a single CBNG well 

would drain the methane from a single coal seam 

over an 80-acre unit. Research by the BLM in the 

Wyoming portion of the Powder River Basin, 

however, suggests that drainage may be across a 

broader radius (Crockett and Meyer 2001) from 

BLM, private, or state lands. The Wyoming BLM 

estimates that considerable methane drainage 

happens when 40 percent of the hydrostatic head is 

removed from the coal aquifer. Modeling by the 

MBMG (Wheaton and Metesh 2002) suggests that 

the hydrostatic head of a producing coal seam could 

be reduced sufficiently to cause methane liberation at 

a distance of approximately two miles from the edge 

of a producing CBNG field. The reduction of 

hydrostatic pressure achieved by lowering the water 

table within a specific coal seam is necessary for 

CBNG production. This reduction liberates the 

methane held in the coal matrix; however, the 

complex, site-specific aquifer conditions dictate the 

actual radius of methane drainage. Therefore, 

conclusions regarding methane drainage from tribal 

minerals need to be made on a case-by-case basis

during development. 

The reduction of the hydrostatic pressure in a coal 

seam and the resulting liberation of CBNG could also 

cause the methane to migrate along the path of least 

resistance and appear as an unchecked seepage at the 

surface. This scenario would be unlikely in view of 

the depths of the coal seams being explored (greater 

than 500 feet below the ground surface), the distance 

of foreseeable producing fields to the reservations

and the relatively shallow groundwater wells used on 

the reservations for water production.

This alternative calls for the directional drilling of 

deeper coal seams, multiple completions in a single 

well bore and the simultaneous development of all 

coal seams within a field. These techniques would 

increase the likelihood that CBNG would be drawn 

from adjacent Indian mineral resources. Detailed 

explanations for these potential impacts can be found 

in the Hydrology, Geology and Minerals and Air 

Quality sections of this Chapter.

Mitigation agreements would be used to replace 

water lost from the drawdown of groundwater within 

aquifers impacted by CBNG production. These 

agreements would call for the replacement of the 

groundwater wells at the operator’s expense. Another 

mitigation measure for large-scale groundwater 

drainage to the reservations is the installation of a 

hydraulic barrier between the production field and the 

reservation boundary. BLM would apply this 
CHAPTER 4

Indian Trust and Native American Concerns

4-141

mitigation measure to reduce and delay any water 

drainage from the reservations. Although hydraulic 

barriers have been used successfully to prevent 

migration of brackish or salty waters into drinking 

water resources, more research would be required to 

determine if they could be employed successfully in 

the coal seam aquifers of the Powder River Basin to 

prevent loss of groundwater resources.

Surface water discharge permits that limit the 

quantity of CBNG-produced water that is discharged 

would mitigate the impacts from Wyoming CBNG

production, as well as from expanded CX Ranch 

production. Potential hydrocarbon migration would 

be the subject of detailed monitoring and periodic 

drainage analysis conducted by the BLM as part of 

their trust responsibility (see Monitoring Appendix 

for details and frequency of monitoring). Monitoring 

and conducting drainage analysis would reduce the 

likelihood for drainage of tribal CBNG resources. 

Native American development of reservation CBNG

resources is another potential mitigation measure that 

would ensure the tribes receive their fair share of the 

CBNG revenues.

Conclusion

Impacts from management decisions included in 

Alternative B would result in impacts to surface 

water quality, groundwater availability, cultural 

artifacts and sites, wildlife, air quality, visibility and

the irreversible loss of fluid and solid minerals.

The surface water quality impacts would be similar to 

those described under Alternative A, with only slight 

alterations to current quality. 

The water drawdown from Montana CBNG

development under Alternative B, coupled with the 

development of CBNG on the reservations, would 

result in a more widespread effect than just adjacent 

to the reservation boundaries. Considering the 

location of known coal occurrences, the groundwater 

drawdown would be experienced generally along the 

eastern portion of the Crow Reservation and across 

the entire Northern Cheyenne Reservation. The water 

drawdown would be contingent on the continuity of 

the coals, many of which are fractured, crop out, 

pinch out or have shale stringers. Impacts could not 

be detailed until the fields are developed. Under any 

scenario of development, the BLM would take 

measures to mitigate reservation groundwater 

drawdown resulting in no contributing influences 

from federal mineral development.

Associated with the development of full-scale CBNG

production across the Powder River Basin are a 

network of gas compressors and other small emission 

sources that could contribute to air quality changes in 

the region. The non-project sources combined with 

the project sources to form a cumulative effect that 

contributions to changes in air quality. These changes 

could add to the pollutant concentration, possibly 

exceeding the Northern Cheyenne’s PSD Class I area 

for the annual NO2 and 24-hour PM10 increment 

standards. If site- specific analysis indicates these 

contributions would add to the pollutant 

concentration on the Lame Deer nonattainment area 

resulting in an exceedance, the tribe, state and the 

Federal Government would require mitigation 

measures to reduce and control the contributing 

sources of CBNG emissions.

The Crow Reservation would experience similar 

changes in air quality, but due to the reservation’s 

classification as a PSD Class II area would not likely 

experience any exceedance of standards.

With regards to visibility, the air model indicates that 

the Crow and Northern Cheyenne reservations would 

experience some form of reduced vision or increased 

haze. Visibility impacts would increase under 

predicted cumulative impacts from project and nonproject emissions. For more detailed discussions 

regarding Air Quality changes to the reservations see 

the Air Quality section of this chapter.

Potential effects to cultural artifacts, TCPs and

wildlife would be mitigated by site-specific 

protective and control measures developed to reduce 

and/or eliminate detrimental changes.

Alternative C—Emphasize CBNG

Development

The differences in management objectives for 

Alternative C that would affect ITAs are the direct 

discharge of a portion of untreated production water

and to some extent, the removal of the directional 

drilling and multiple completion requirements. 

Impacts to air quality, visibility, cultural resources, 

wildlife and social services and infrastructure would 

be the same or similar to those described for 

Alternative B.

Important to note is that, depending on the water 

quality criteria developed by the MDEQ, various 

levels of impacts on surface water would occur. If the 

criteria imposed were to be relatively conservative, 

the discharge of CBNG produced water would be 

limited into watersheds of both low and high water 

quality, resulting in minimal surface water quality 

impacts and increased treatment and use of 

alternative disposal methods. On the other hand, if 

the criteria were to be somewhat liberal and allow 

untreated discharge of produced CBNG water into 
CHAPTER 4

Indian Trust and Native American Concerns

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watersheds of higher quality, then impacts such as the 

following would be experienced: increased soil 

erosion and a corresponding increase in the addition 

of suspended sediment to surface waters adjacent to 

CBNG development; the elevation of existing SAR, 

EC and bicarbonate values for streams and rivers 

used by the tribes for irrigation; and the increase in 

flow that would result in riparian erosion and river 

course changes. These impacts are discussed in 

further detail in the Hydrology section of this chapter.

Impacts on groundwater would consist of the same 

drawdown effects as described in Alternative B. The 

development of federal minerals near the reservations 

would increase the rate at which the groundwater is 

removed and discharged to the surface. Additionally, 

impacts on shallow aquifers from the infiltration of 

untreated produced water are expected where the 

soils have a coarser texture (sandy to loamy) and 

good internal drainage (ALL 2001a), which would 

allow infiltration of produced water into subsoilthereby impacting shallow aquifers. Some of the 

shallow aquifers adjacent to reservation boundaries 

would be affected by this type of short-term 

infiltration.

The discharge of untreated produced water into 

drainages and ephemeral watercourses adjacent to 

well sites would cause an overall increase in erosion 

leading to gullying. Based on the Soils Technical 

Report (ALL 2001a), much of the soil would likely 

be susceptible to increasing sodicity when irrigated or 

land applied with water having a high SAR 

(generally greater than 12). The long-term 

consequence is an anaerobic, waterlogged, 

saline/sodic soil that can be reclaimed, but would be 

very difficult to mitigate.

Drainage of Native American CBNG resources by 

adjacent production would be similar to that 

described for Alternative B for adjacent production. 

Site-specific conditions control methane liberation 

and collection and therefore, to evaluate potential 

drainage, a case-by-case drainage determination is 

necessary. 

Encroachment on the Absaloka Coal Mine by CBNG

development would inhibit future coal resource 

recovery. Impacts associated with the groundwater 

drawdown would also occur. This is discussed further 

in the Geology and Minerals section of this chapter.

Conclusion

Impacts from management decisions included in 

Alternative C would result in impacts to surface 

water quality. State and private development would 

reduce groundwater availability and cause the 

irreversible loss of fluid minerals.

The impacts to surface water quality would be greater 

than described in Alternative B, but the biggest 

factors influencing water quality would be the 

creation of a Water Quality Agreement between 

Montana and Wyoming and the implementation of 

water quality criteria regarding degradation of 

Montana watersheds by the MDEQ. CBNG

development on reservations would further increase 

the SAR value of available surface waters, adding to 

the chain reaction of impacts associated with erosion, 

sedimentation, riparian damage and land use 

applications.

Impacts on the Northern Cheyenne’s water right in 

the Tongue River Reservoir would be as described 

under Alternative A. 

Impacts on groundwater drawdown and availability 

would be similar to those explained under 

Alternative B. Drawdown adjacent to the reservations 

would be increased. 

Monitoring and drainage analysis would be necessary 

to evaluate the case-by-case CBNG drainage of 

adjacent fields. As stated under Alternative B, the 

timely development of CBNG on reservations would 

reduce the potential for adjacent mineral drainage, 

but would increase the likelihood of proximityrelated impacts to the Absaloka Coal Mine.

The impacts on lands irrigated by streams and rivers 

receiving untreated CBNG discharge would be as 

described in the Soils Technical Report (ALL 2001a)

and would be greatly dependent on the altered quality 

of the particular watershed being used. Increased soil

erosion leading to gullying would be a result of 

development on the reservations along with erosion 

outside reservation boundaries.

Impacts to air quality, visibility, cultural resources, 

wildlife, social services and infrastructure would be 

the same or similar to those described for 

Alternative B.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

The only differences in management objectives for 

Alternative D that would have an effect on ITAs is 

the treatment and piped conveyance of production 

water. This difference would reduce the impacts to 

erosion along ephemeral drainages, lower the 

sediment load in watercourses and limit the water 

quality impact to both surface water and 
CHAPTER 4

Indian Trust and Native American Concerns

4-143

groundwater. There would be an increase in available 

surface water for beneficial reuse because of the 

required treatment and lack of conveyance losses 

from the piped system of discharge. The lack of 

conveyance losses would increase the flow in 

receiving watercourses resulting in course changes 

and riparian alterations, as identified in 

Alternative A. 

Groundwater drawdown would be as described in 

Alternative B because of the use of the buffer zone 

by the BLM. Mineral drainage also would be the 

same as discussed under Alternative B, with the use 

of monitoring required to evaluate the case-by-case 

field conditions. Irrigated lands would be less 

affected by the use of treated waters, as described in 

the Soils section of this chapter. The Absaloka Coal 

Mine would experience the same groundwater 

drawdown impacts as described under Alternative B. 

Impacts to visibility, cultural resources, wildlife, 

social services and infrastructure would be the same 

or similar to those described for Alternative B on all 

reservations. Impact to air quality on all reservations 

would be lower than Alternative B.

Conclusion

Impacts from management decisions included in 

Alternative D, management practices common to all 

alternatives and from projects evaluated under the 

cumulative effects analysis would result in increased 

surface water flow, reduction of groundwater 

availability and the irreversible loss of fluid minerals.

Impacts on surface water quality would be similar to 

those discussed under Alternative B with regard to 

the influence of Wyoming’s CBNG production 

waters entering Montana and affecting the Northern 

Cheyenne water right in the Tongue River Reservoir. 

With the increase in flow from the treated waters in 

Montana, the overall SAR values would be adjusted 

downward, but only slightly. CBNG development on 

reservations would further add to available surface 

waters once treatment is administered; groundwater 

drawdown would be the same as discussed in 

Alternative B. Soil erosion would be decreased 

because of the use of conveyance systems, which 

would result in the reduction of suspended solids in 

watercourses and the elimination of gullying. The 

impacts on lands irrigated by streams and rivers 

receiving treated CBNG discharge would be reduced. 

Impacts to air quality, visibility, cultural resources, 

wildlife, social services and infrastructure would be 

the same or similar to those described Alternative B. 

Impacts to air quality on all reservations would be 

lower than those discussed under alternative B.

As stated under Alternative B, the timely 

development of CBNG on reservations would reduce 

the potential for adjacent fluid minerals drainage, but 

would increase the likelihood of proximity-related 

impacts to the Absaloka Coal Mine.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

The management objectives for Alternative E would 

result in surface water, groundwater and potential 

methane drainage impacts similar to those described 

under Alternative E in the Hydrology section. 

Noteworthy are the approved Draft Surface Water 

Quality Standards of the Northern Cheyenne Tribe, 

which if approved by EPA, could result in restricted 

discharges in the Tongue River and Rosebud Creek. 

Regardless of what choice is made, impacts would 

resemble those described under Alternative E in the 

Hydrology section of this chapter. There would be no 

discharge of produced water (treated or untreated) 

into the watershed unless the operator has an 

approved NPDES permit and can demonstrate in their 

Water Management Plan how discharge could occur 

in accordance with water quality laws. 

Impacts on groundwater would consist of the same 

drawdown effects as described in Alternative B, 

however, implementation of the BLM mitigation

measures would reduce the likelihood that 

reservation water resources would be drained from 

off-reservation CBNG activities. 

Water quality impacts from infiltration would be 

minimized as a result of the design and placement of 

impoundments. Impoundments proposed as part of 

the Water Management Plan would be designed and 

located to minimize or mitigate impacts to soil, 

water, vegetation and channel stability reducing 

infiltration impacts to groundwater quality. In 

addition, impoundments are required to be permitted 

under the MDEQ General MPDES permit that 

includes additional conditions to minimize impacts to 

groundwater (see Hydrology Appendix).

Impacts on Native American hydrocarbons via 

adjacent production drainage would be similar to 

those described for Alternative C. As previously 

mentioned, site-specific conditions control methane 

liberation and collection and therefore, to evaluate 

potential drainage, a case-by-case study is necessary. 

These studies would be required as part of the APD 

approval process, along with intensified monitoring 

to determine when and if tribal CBNG resources 
CHAPTER 4

Indian Trust and Native American Concerns

4-144

would be drained. If drainage is likely, the BLM 

would require the operator to take appropriate action, 

in consultation with the tribes, to reduce or eliminate 

the drainage, or in the case of a federal well, to 

compensate the tribe for the loss. 

As discussed earlier under Alternative C, the 

Absaloka Coal Mine could be encroached on by 

CBNG development but wells could not be drilled 

within permitted coal mining acres. The coal is held 

in trust for the Crow Tribe. 

As for impacts to air quality, visibility, cultural 

resources, wildlife, social services and infrastructure 

these would be reduced from those described under 

Alternative B because of the control measures 

employed with each site-specific Project Plan and the 

other management features of this alternative 

discussed in Chapter 2. 

Mitigation measures have been developed to protect 

the Northern Cheyenne Tribal resources, as well as 

culturally important off-reservation sites. A 

discussion of these mitigation measures is presented 

in the Northern Cheyenne Mitigation Appendix. 

These mitigation and monitoring measures have been 

designed to provide the BLM and the tribe with 

additional information regarding measures that would 

be used to protect site-specific resources such as 

groundwater, CBNG, air quality, wildlife, vegetation

and cultural resources. 

Conclusion

Impacts from management decisions included in 

Alternative E have the potential to result in a slight 

decrease to surface water quality and a minimal 

reduction in groundwater availability.

Impacts to the Northern Cheyenne’s water right in 

the Tongue River Reservoir would be as described 

under Alternative A.

Potential impacts on reservation groundwater 

drawdown and availability would be mitigated by the 

implementation of specific BLM control measures. 

Potential impacts to groundwater would be identified 

early by the intensified monitoring planned under 

Alternative E. 

Monitoring and drainage analysis would be 

conducted by the BLM to evaluate the potential for 

CBNG drainage. If monitoring indicated tribal

resources were impacted measures such as 

production decreases or well shut-in would be 

instituted and the appropriate tribal compensation 

agreement implemented. 

The impacts to lands irrigated by streams and rivers 

receiving CBNG discharge would be minimal as only 

slight alterations in surface water quality are 

anticipated. 

Impacts to air quality, visibility, cultural resources, 

wildlife, social services and infrastructure would be 

reduced from those described under Alternative B 

because of the mitigation measures employed with 

each site specific Project Plan and the other 

management features of this alternative discussed in 

Chapter 2. Cultural resources include important offreservation hunting, fishing and plant gathering sites.

Impacts to the Northern Cheyenne Reservation

resources would be mitigated by the implementation 

of control measures described by the BLM in the 

Northern Cheyenne Mitigation Appendix. 

Alternative F—Phased Development 

Multiple Screens (High Range)

Alternative F would result in reduced surface water, 

groundwater and methane drainage impacts to Indian 

Trust Assets as compared to Alternative E. This is 

due to the use of the 5-mile buffer zone, the 10

percent of the 7Q10 discharge threshold for federal 

minerals and enforcement of additional monitoring 

requirements for federal mineral development within 

this zone.

The MDEQ has set numerical criteria for surface 

water discharges within the Powder River Basin 

watersheds. These standards are displayed in Table 3-

6. Direct, untreated discharge into stream is no longer 

permitted. Some existing operations obtained permits

prior to this ruling and may continue to discharge 

limited amounts (1,600 to 2,500 gpm) of untreated 

CBNG produced water directly into the Tongue 

River. These permits are flow-based and allow 

increased regulated discharges during certain higher 

flow conditions. The new permit standards may result 

in restricted discharge to most rivers and streams in 

the CBNG emphasis area. This restricted discharge 

would most likely increase impoundment use, either 

as a means of disposal or storage prior to treatment. 

Regardless of what choice is made, impacts would 

resemble those described under Alternative F in the 

Hydrology section of this chapter. There would be 

no, or very limited, discharge of produced water 

(treated or untreated) into the watersheds from 

federally developed minerals due to the curtailment 

of the discharge by the threshold limit of 10 percent

of the 7Q10. 

Impacts on groundwater would consist of the same 

drawdown effects as described in Alternative B; 

however, implementation of the BLM mitigation
CHAPTER 4

Indian Trust and Native American Concerns

4-145

measures coupled with the 5-mile monitoring 

proximity would further reduce the likelihood that 

any reservation water resources would be drained 

from off-reservation federal CBNG activities. 

Current monitoring at the CX field as gauged by 162 

monitoring wells indicate that draw-down 

measurements after more than four years of 

production are 20 feet extending 1-2 miles (Wheaton 

and Donato 2004). Groundwater monitoring indicates 

drawdown is "similar to but somewhat less than 

expected" from the groundwater modeling conducted 

for the Statewide Document (Wheaton et al. 2005). 

Water quality impacts from infiltration would be 

minimized as a result of the design and placement of 

impoundments. Impoundments proposed as part of 

the Water Management Plan would be designed and 

located to minimize or mitigate impacts to soil, 

water, vegetation and channel stability reducing 

infiltration impacts to groundwater quality. In 

addition, any impoundments within 5-miles of the 

reservations would be monitored for infiltration 

effects to groundwater quality.

Impacts on Native American hydrocarbons via 

adjacent state or private production drainage would 

be similar to those described for Alternative C. The 

required drainage analysis and follow-up studies for 

operators extracting federal minerals within 5 miles 

of the reservations would further reduce the 

likelihood of tribal resources being drained. If 

drainage is determined to be likely, the BLM would 

require the operator to take appropriate action. The 

action would consist of consultation with the affected 

tribes, implementation of measures to reduce or 

eliminate the drainage, or in the case of a federal 

well, shut-in production until a later date when the 

drainage issue can be mitigated. 

As discussed earlier under Alternative C, the 

Absaloka Coal Mine could be encroached on by 

CBNG development but wells could not be drilled 

within permitted coal mining acres. The coal is held 

in trust for the Crow Tribe. 

The potential for impacts to air quality, visibility, 

wildlife, social services and infrastructure would be 

less than under Alternative E because of the control 

measures employed with each site-specific Project 

Plan and the general leveling out of the development 

pace for CBNG across the basin. More 

comprehensive air quality analysis and possibly 

monitoring would also be required for PODs 

submitted within 5 miles of the reservation exterior 

boundary. 

Mitigation measures would help protect Northern 

Cheyenne tribal resources and off-reservation sites, 

such as the Rosebud and Wolf Mountain Battlefields, 

known to be of special importance to the tribe. A 

discussion of these mitigation measures is presented 

in the Northern Cheyenne Mitigation Appendix. 

These mitigation and monitoring measures have been 

designed to help protect resources such as 

groundwater, CBNG, air quality, wildlife, vegetation

and off-reservation cultural resources of special 

interest to the tribe. 

The Northern Cheyenne Tribe also has offreservation properties held in trust that consist of two, 

tracts of land, approximately 160 acres each, in the 

vicinity of the Tongue River Reservoir. The tribe also 

acquired off-reservation surface estate consisting of 

the Moreland Ranch property. The mineral estate for 

the Moreland Ranch property is owned by the 

Consolidated Coal Company and could be subject to 

development; however it is currently not leased. The 

BLM would consult with the tribe to determine what 

mitigation measures are needed to protect the surface 

use of the ranch. Tribal buffalo herds are pastured at 

the Moreland Ranch property.

With regard to off-reservation TCPs and cultural 

artifacts the BLM has implemented a cultural survey 

requirement for the majority of CBNG lands to be 

developed under each POD. The use of these “block 

surveys” coupled with tribal consultation 

requirements has demonstrated the ability to identify 

the majority of sites that could be affected and reduce 

the potential impacts associated with developing 

CBNG in the vicinity of cultural resources.

Furthermore, on January 12, 2006, the BLM Montana 

State Office issued additional cultural resource 

requirements for oil and gas operations in Montana 

and the Dakotas. These requirements are intended for 

both oil and gas operators and cultural resource 

consultants hired by oil and gas operators. They 

supplement the Guidelines for Identifying Cultural 

Resources H-8110-1 (the handbook) which remains 

the basic guidance for cultural resource work 

completed for BLM undertakings. Notice to Lessees, 

NTL-MSO-1-85, provides guidelines to operators 

when they are required to conduct cultural resource 

inventories. The NTL establishes the minimum 

survey area of 10 acres centered on each proposed 

well plus the access road, pipeline and ancillary areas 

subject to surface disturbance. Washington Office IM 

No. 2003-147 (BLM 2003c) recommends block 

surveys ranging from 40 acres for individual wells to 

entire lease or full field development areas for largescale projects to improve the APD process. Block 

surveys offer many advantages including reducing 

the probability that multiple surveys will be required 

to site a single project. Additionally, operators are 
CHAPTER 4

Indian Trust and Native American Concerns

4-146

encouraged to complete cultural resource surveys 

prior to the onsite inspection. This will allow the well 

location and/or access route to be sited prior to the 

onsite in order to avoid adverse effects on cultural 

resources and reduce the likelihood of having to 

change a location due to a cultural resource conflict 

discovered later in the APD review process. 

Conclusion

Impacts from management actions under

Alternative F have the potential to preserve surface 

water quality and minimize the drawdown of 

groundwater on the reservations. 

Impacts to the Northern Cheyenne Tribe’s water right 

in the Tongue River Reservoir would be as described 

under Alternative A.

Potential impacts on reservation groundwater 

drawdown and availability would be mitigated by the 

implementation of specific BLM control measures. 

Potential impacts to groundwater would be identified 

by the use of the 5-mile analysis requirement under 

Alternative F. 

Monitoring and drainage analysis would be 

conducted by the BLM and operators to evaluate the 

potential for CBNG drainage. If monitoring indicated 

tribal resources were to be impacted measures such 

as production decreases or well shut-in would be 

instituted. 

The impacts to lands irrigated by streams and rivers 

receiving CBNG discharge would be further reduced 

as only state and private untreated discharge would 

be likely. 

Impacts to air quality, visibility, wildlife, social 

services and infrastructure would be reduced from 

those described under Alternative E because of the 

pace of development coupled with existing mitigation

measures employed with each site specific Project 

Plan. 

Cultural resources, including important offreservation hunting, fishing and plant gathering sites

would be identified within the POD development 

process due to the use of surveys and tribal 

consultation efforts.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Effects under Alternative G would be the same as 

Alternative F but would be reduced by approximately 

65 percent based on the fewer number of APDs that 

are predicted to be issued. Under Alternative G, the 

annual cumulative limit placed on federal APDs 

approved by BLM would be set at five percent (323

APDs) of the low-range of state, private and federal 

CBNG APDs (6,470) predicted to be approved in the 

Planning Area (as identified in the Reasonably 

Foreseeable Development scenario in the Statewide 

Document). This would result in a 65 percent

reduction in activities related to CBNG development 

that could potentially have an effect on tribal 

resources or off-reservation sites of special interest.

Alternative H—Preferred Alternative - 

Multiple Screens 

Under this Alternative, impacts to federal leases, 

CBNG resources and federal lessees would be similar 

to Alternative F. This Alternative manages the pace 

(rate) and place (geography) of federal CBNG 

development through protection measures applied to 

crucial habitat areas and limits to the discharge of 

untreated produced water from federal CBNG wells 

and emissions from sources associated with federal 

CBNG wells. More federal APDs could be approved 

annually and geographically than under Alternatives 

F and G as long as other resources are protected. 

Monitoring data would be required to help BLM 

determine which (where and when) federal APDs 

could be approved. These limits and thresholds (see 

Wildlife Appendix and Hydrology section) would 

serve to level the cumulative impacts over time. The 

production of CBNG would continue for a longer 

overall period of time compared to Alternative E 

because fewer number of federal CBNG wells may 

be drilled each year.

Alternative H would result in reduced surface water, 

groundwater and methane drainage impacts to Indian 

Trust Assets as compared to Alternative E. This is 

due to the use of the 5-mile buffer zone and 

enforcement of additional monitoring requirements 

for federal mineral development within this zone.

The MDEQ has set numerical criteria for surface 

water discharges within the Powder River Basin 

watersheds. These standards are displayed in 

Table 3-6. Direct stream discharge is no longer 

permitted on new wells. Existing operations were 

"grandfathered" in and are discharging directly into 

streams. Also, proposals are being considered to 

allow regulated discharges during certain flow 

conditions. These efforts would result in restricted 

discharge to most rivers and streams in the CBNG 

emphasis area and flow based discharge with 

increased impoundment use. Regardless of what 

choice is made, impacts would resemble those 

described under Alternative H in the Hydrology 

section of this chapter. There would be no or very 

limited discharge of produced water (treated or 
CHAPTER 4

Indian Trust and Native American Concerns

4-147

untreated) into the watersheds from federally 

developed minerals due to the curtailment of the 

discharge by the threshold limit of 10 percent of the 

7Q10. 

Implementation of the BLM mitigation measures

coupled with the 5-mile monitoring proximity would 

reduce the likelihood that any reservation 

groundwater resources would be drained from offreservation federal CBNG activities. Current 

monitoring at the CX field as gauged by 162 

monitoring wells indicates that drawdown 

measurements after more than four years of 

production are 20 feet extending 1-2 miles (Wheaton 

and Donato 2004). Groundwater monitoring indicates 

that drawdown is "similar to but somewhat less than 

expected" from the groundwater modeling conducted 

for the Statewide Document (Wheaton et al. 2005)

Water quality impacts from infiltration would be 

minimized as a result of the design and placement of 

impoundments. Impoundments proposed as part of 

the Water Management Plan would be designed and 

located to minimize or mitigate impacts to soil, 

water, vegetation and channel stability reducing 

infiltration impacts to groundwater quality. In 

addition, any impoundments within five miles of the 

reservations would be monitored for infiltration 

effects to groundwater quality.

Impacts on Native American hydrocarbons via 

adjacent state or private production drainage would 

be similar to those described for Alternative B. The 

required drainage analysis and follow-up studies for 

operators extracting federal minerals within five

miles of the reservations would further reduce the 

likelihood of tribal resources being drained. If 

drainage is determined to be likely, the BLM would 

require the operator to take appropriate action. The 

action would consist of consultation with the affected 

tribes, implementation of measures to reduce or 

eliminate the drainage, or in the case of a federal 

well, shut-in production until a later date when the 

drainage issue can be mitigated. 

The Absaloka Coal Mine could be encroached on by 

CBNG development but wells could not be drilled 

within permitted coal mining acres. The coal is held 

in trust for the Crow Tribe. Encroachment on the 

Absaloka Coal Mine by CBNG development would 

create impacts associated with the groundwater 

drawdown. Increased coal bed aquifer drawdown 

could benefit the mine from methane extraction prior 

to coal removal, but could hinder and complicate 

aquifer restoration efforts once mining activities 

cease. In addition, the removal of coal seam water 

may create a situation where the coal mine would 

need to purchase water for dust control.

The potential for impacts to air quality, visibility, 

wildlife, social services and infrastructure would be 

less than under Alternative E because of the use of 

the air quality screen. The screen would be used to 

require modifications be made to existing operations 

if observed effects and modeled impacts completed 

for the annual review by MDEQ show that state or 

federal regulatory standards would be exceeded. 

Under these circumstances the BLM could 

disapprove additional CBNG APDs if available 

monitoring and air modeling of new proposals 

indicated effects that violate state or federal 

regulatory standards. In such cases BLM would first 

consider mitigation measures that would reduce 

impacts so that actions would comply with such 

standards. Furthermore, management direction under 

this alternative requires control measures to be 

employed with each site-specific Project Plan, 

maximum number of wells connected to each 

compressor and use of natural gas or electrical 

compressors only.

Mitigation measures would help protect Northern 

Cheyenne Tribal resources and off-reservation sites, 

such as the Rosebud and Wolf Mountain battlefields, 

known to be of special importance to the tribe. A 

discussion of potential mitigation measures is 

presented in the Northern Cheyenne Mitigation 

Appendix. These mitigation and monitoring measures 

have been designed to help protect resources such as 

groundwater, CBNG, air quality, wildlife, vegetation 

and off-reserbation cultural resources of special 

interest to the tribe. 

The Northern Cheyenne Tribe also has offreservation properties held in trust that consist of two 

tracts of land, approximately 160 acres each, in the 

vicinity of the Tongue River Reservoir. The tribe also 

acquired off-reservation surface estate consisting of 

the Moreland Ranch property. The mineral estate for 

the Moreland Ranch property is owned by the 

Consolidated Coal Company and could be subject to 

development; however it is currently not leased. The 

BLM would consult with the tribe to determine what 

mitigation measures are needed to protect the surface 

use of the ranch. Tribal buffalo herds are pastured at 

the Moreland Ranch property.

With regard to off-reservation TCPs and cultural 

artifacts the BLM has implemented a cultural survey 

requirement for the majority of CBNG lands to be 

developed under each POD. The use of these “block 

surveys” coupled with tribal consultation 

requirements has demonstrated the ability to identify 

the majority of sites that could be affected and reduce 

the potential impacts associated with developing 

CBNG in the vicinity of cultural resources.
CHAPTER 4

Indian Trust and Native American Concerns

4-148

Furthermore, on January 12, 2006 the BLM Montana 

State Office BLM issued additional cultural resource 

requirements for oil and gas operations in Montana 

and the Dakotas. These requirements are intended for 

both oil and gas operators and cultural resource 

consultants hired by oil and gas operators. They 

supplement the Guidelines for Identifying Cultural 

Resources H-8110-1 (the handbook), which remains 

the basic guidance for cultural resource work 

completed for BLM undertakings. Notice to Lessees, 

NTL-MSO-1-85, provides guidelines to operators 

when they are required to conduct cultural resource 

inventories. The NTL establishes the minimum 

survey area of 10 acres centered on each proposed 

well plus the access road, pipeline and ancillary areas 

subject to surface disturbance. Washington Office IM 

No. 2003-147 (BLM 2003c) recommends block 

surveys ranging from 40 acres for individual wells to 

entire lease or full field development areas for largescale projects to improve the APD process. Block 

surveys offer many advantages including reducing 

the probability that multiple surveys will be required 

to site a single project. Additionally, operators are 

encouraged to complete cultural resource surveys 

prior to the onsite inspection. This will allow the well 

location and/or access route to be sited prior to the

onsite in order to avoid adverse effects on cultural 

resources and reduce the likelihood of having to 

change a location due to a cultural resource conflict 

discovered later in the APD review process.

Conclusion

Impacts from management actions under

Alternative H would be the same as under 

Alternatives F and G.

Potential impacts on reservation groundwater 

drawdown and availability would be mitigated by the 

implementation of specific BLM control measures. 

Potential impacts to groundwater would be identified 

by the use of the 5-mile analysis requirement. 

Monitoring and drainage analysis would be 

conducted by the BLM and operators to evaluate the 

potential for CBNG drainage. If monitoring indicated 

tribal resources were to be impacted measures such 

as production decreases or well shut-in would be 

instituted. 

The impacts to lands irrigated by streams and rivers 

receiving CBNG discharge would be further reduced 

as only state and private untreated discharge would 

be likely. 

Impacts to air quality, visibility, wildlife, social 

services and infrastructure would be reduced from 

those described under Alternative E because of the 

pace of development coupled with existing mitigation

measures employed with each site specific Project 

Plan 

Cultural resources, including important offreservation hunting, fishing and plant gathering sites

would be identified within the POD development 

process due to the use of surveys and tribal 

consultation efforts.
CHAPTER 4

Lands and Realty

4-149

Lands and Realty

Lands and Realty

Planning Area Land Ownership:

 - Private 69% 

 - Federal 15% 

 - Tribal 10%

 - State 5%

Total Acreage:

19,371,593

Miles of Road:

 - Interstate, 386

 - US, 675

 - State, 409

 - Off-System,

24,431

Miles of Railroad:

 - Burlington Northern Santa 

Fe (BNSF), 573

- MontanaRail Link, 146

Alternative A

No Action (Existing CBNG Management)

• Federal:

− Minimal land area displaced by roads.

− 400 acres disturbed during CBNG exploration drilling. 

• State:

− Increased motorized access on the CX Ranch.

− Increase motorized trespass.

− 1,100 acres disturbed during CBNG exploration and 

production activities.

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Federal:

− Increase fire hazard and motorized access. 

− 25,600 acres disturbed during CBNG development 

activities.

• State:

− Displace agricultural lands.

− Disrupt irrigation system, increase cost of farm 

operation.

− Reduced property values.

− Displace community and residential growth. 

− Increase dust and noise impacts on residential use.

− Increased cost of county road maintenance. 

− Increase long-term motorized access. 

− 29,750 acres disturbed during CBNG development.

Alternative C

Emphasize CBNG Development

• All impacts in Alternative B occur in Alternative C in addition 

to:

− The land use displacement from roads and utility lines 

during lease operations is greatest in Alternative C 

− 70,000 acres would be disturbed by CBNG activities on 

private, state and federal lands

Alternative D 

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• All impacts in Alternative B occur in Alternative D in addition 

to: 

− Federal: Permanent loss of land use from road network. 

Alternative E

CBNG Exploration and Development with Enhanced Mitigation 

to Minimize Environmental Impacts While Maintaining 

Existing Land Uses

• Levels of disturbance would be 27 percent greater than 

Alternative B because transportation corridors and the use of 

existing disturbed lands would not be required for roads and 

utilities. 

• Impacts from power lines, roads, pipelines and other utilities not 

requiring transportation corridors would be the same as 

Alternative C. 

Alternative F

High Range Phased CBNG Development

• Federal:

− 25,600 acres disturbed during CBNG exploration and 

construction activities (short-term).

− 15,250 acres disturbed during operation (long-term).

• State:

− 29,550 acres disturbed during CBNG exploration and 

construction activities (short-term).

− 17,600 acres disturbed during operation (long-term).

• 88,170 acres cumulative effects. 

• If no development occurs in crucial sage-grouse habitat, 

cumulative impacts would be reduced to 82,527 acres (6.4% 

reduction from 88,170 acres).

Alternative G 

Low Range Phased CBNG Development

• Levels of disturbance are 65 percent less than Alternative F.

• Federal:

− 9,100 acres disturbed during CBNG exploration and 

construction activities (short-term).

− 5,400 acres disturbed during operation (long-term).

• State:

− 10,500 acres disturbed during CBNG exploration and 

construction activities (short-term).

− 6,250 acres disturbed during operation (long-term).

• 20,450 acres cumulative effects. 

Alternative H 

Preferred Alternative

• Federal:

− 25,600 acres disturbed during CBNG exploration and 

construction activities (short-term).

− 15,250 acres disturbed during operation (long-term).

• State:

− 29,500 acres disturbed during CBNG exploration and 

construction activities (short-term).

− 17,600 acres disturbed during operation (long-term).

• 88,170 acres cumulative effects.
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Assumptions 

Gas from CBNG wells is normally measured at the 

well site or on a collection line before mixing at field 

compression stations, making it possible for flow 

lines and compression stations to be shared by 

different operators to reduce development cost and 

surface disturbance. 

Split estate surface owners have the right to maintain 

control of non-CBNG related access. 

Operators are responsible for communicating 

requirements and stipulations to independent 

contractors working on behalf of the operator when 

performing various phases of CBNG exploration and 

production development. 

There are no expected disruptions to existing fiber 

optic, phone, gas, electric, or water lines as a result of 

the construction, production, or abandonment of 

project alternatives. It is the responsibility of the 

operator to identify and avoid buried lines within the 

pathway of new surface-disturbing activities. 

According to the Farmland Protection Policy Act, 

federal agencies involved in proposed projects that 

may convert farmland to non-agricultural uses must 

complete a USDA Farmland Conversion Impact 

Rating Form AD-1006. The form focuses on two 

farmland designations: prime farmland and 

agricultural lands of statewide importance. Prime 

farmland and agricultural lands designations are 

based on soil type and productivity and are not based 

on present use. The AD-1006 form would be 

completed for each APD application or as part of an 

Environmental Assessment (EA) checklist to assess 

impacts to agriculture on federal lands.

No physical displacements of residences or 

commercial property would result from project 

alternatives.

CBNG-related, human activity increases fire hazards 

in the Planning Area. The loss of vegetation by fire 

would impact all land uses including ranching, 

recreation and agriculture and would limit access to 

public lands because reclamation would be sensitive 

to soil disturbance.

The required reclamation plan by the operator would 

be reviewed and approved by BLM on federal lands, 

by the state on state lands and by the landowner on 

private lands.

Impacts from Management Common 

to All Alternatives

Potential land use impacts would primarily consist of 

conflicts between conventional oil and gas activities 

and other uses of property, such as agriculture, 

residences and coal mines. New authorizations for 

major gathering lines, major transportation lines and

power lines, for example, would impact rights-ofway (ROWs) and land segmenting. The development 

of oil and gas resources impacts agricultural 

production by taking land out of production and by 

soil contamination from drilling and production 

activities.

Surface disturbance associated with oil and gas 

activities, such as roads, well pads and battery sites 

would remove those areas of agricultural production 

during the life of the road, well pad, or tank battery 

site. Removal of vegetation would reduce the acreage 

available for livestock grazing or crop production. 

Buried flowline and utility line routes would be 

seeded so the acreage would be temporarily removed 

from use for grazing or crop production. The 

infrastructure associated with oil and gas production 

could affect the movement or area available for 

livestock and could hinder irrigation systems.

Most existing roads would be lightly traveled by 

local residents, ranchers and oil and gas workers. Use 

of unimproved roads would increase because of daily 

operations for a month at each site during 

development and testing of exploration wells. This 

road activity would be increased in general areas 

targeted for well development. Unimproved roads 

would be vulnerable to damage in adverse weather 

conditions. Public and private lands could be 

impacted by driving on soft or unstable road surfaces. 

Residents and public visitors would be impacted by 

the sights, sounds and delays caused by the 

construction and testing of exploratory and 

production wells. An increase in slow-moving 

vehicles would be an impact in areas not currently 

experiencing these activities. Creation of a 

temporary, unimproved, unrestricted access road to 

an area would allow public access and exposure of 

the property in a new way and would expand the road 

system requiring maintenance by federal or state 

agencies and private landowners. 

Public access to most wells would likely be limited 

because 69 percent of the land area is private; 

however, there would be conflicts with recreation 

(see the Recreation section of this chapter). Shortterm impacts would occur during road building, pad 

development, drilling and production-related 
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activities. Access for recreation on legally accessible 

public lands would increase as a result of the increase 

in unimproved roads. These impacts would be 

viewed as a benefit to sportsmen, who generally 

support increased vehicle access. Road densities on 

private lands would likely increase in the areas 

targeted for oil and gas wells, but property owners 

would be responsible for access control.

CBNG development would increase the likelihood of 

fire because there would be potential incendiary 

activities occurring where none now occur. Specific 

causes may include methane leaks, electrical fires 

from drilling and other construction activities, fires 

from ruptured gas pipelines, careless smokers, gas 

migrating from domestic wells contaminated with 

methane gas and hot catalytic converters on vehicles.

Produced water of quality suitable for livestock could 

be placed in impoundments in areas currently without 

such impoundments for livestock. This would 

enhance or expand livestock grazing. Construction 

disturbance would also force cattle onto previously 

unused range, further changing land use (see 

discussion on Livestock Grazing). Similar 

displacement would occur for wildlife, disrupting 

hunting on land designated for controlled or general 

hunts.

There may be a trespass impact to private landowners 

from the conversion of unroaded federal lands with a 

right-of-way that now allows access to private lands. 

On private and public lands, road maintenance would 

be specified in the lease agreement, drilling permit or 

Right of Way as the responsibility of either the 

contractor or landowner.

Complete removal of the indication of vehicle 

passage and revegetation of two-track exploration on 

public lands would be important to prevent these 

temporary roads from becoming an established 

access through consistent misuse by four-wheel-drive 

and all-terrain vehicles, especially in areas 

historically not accessed by vehicles. The Vegetation

section describes the seeding policy for reclaiming 

surface disturbances. 

Activities other than those associated with CBNG 

production are expected to result in additional land 

disturbance. These activities include conventional oil 

and gas, active coal mines, fires, highway projects, 

power plants and the proposed Tongue River

Railroad.

The proposed Tongue River Railroad would require 

the acquisition of 447 to 636 acres for the ROW. 

Land within the ROW would be lost to its present use

and some parcels would be intersected by the rail 

line, possibly resulting in a change in existing use. 

Construction of the railroad would increase vehicle 

use and maintenance of local roads in the project area 

over the short term, while travel along these roads 

would also be affected over the long term by delays 

from grade-level train crossings (STB 2004). 

Impacts From Management Specific 

To Each Alternative

Alternative A—No Action (Existing CBNG 

Management) 

Impacts on multiple uses of public lands would be 

minimal because there would be no CBNG 

production development on federal lands. State and 

private lands would have limited CBNG production 

activities. 

Exploration

The amount of new roads to be built would be 

minimal relative to other alternatives. The primary 

land use impacts on federal and state lands are from 

short-term direct land use displacement by 

exploratory well pads and the creation of two-track 

trails across prairie or other lands from exploratory 

equipment. Impacts on private lands would be largely 

addressed in the contractual agreement with the 

private owners of the CX Ranch.

Production

Newly created roads for CBNG production would 

increase access across the CX Ranch that may 

displace or change the land use patterns on the land. 

Abandonment

Two-track trails and associated motorized access

created by CBNG exploration on federal and state 

lands would be reclaimed after abandonment, unless 

otherwise authorized. New access created under a 

ROW may be reclaimed depending on the situation 

and the BLM and surface owner’s requirements. New 

motorized access in watersheds targeted for water 

quality restoration by MDEQ may require road 

reclamation as part of abandonment. Reclamation 

based on water quality would be on a case-by-case 

basis with involvement from MDEQ. Abandonment 

and reclamation of roads on the CX Ranch could be 

highly variable according to the agreement with the 

surface owner. Abandonment impacts on private land 

cannot be determined because of its variability, but 

private landowners would be able to negotiate 

reclamation agreements to avoid long-term impacts 

to their land. Unwanted roads on the CX Ranch 
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would be obliterated and revegetated according to the 

agreement with the lease operator. 

Crow Reservation

Impacts on the Crow Reservation would be the same 

as described in general for Alternative A. If there 

were no CBNG development on tribal Lands, then 

there are expected to be minimal, if any, impacts to 

the reservation. Trespassing from CBNG related

vehicles might increase because of activities adjacent 

to the reservation. Traffic is also expected to increase 

on reservation roads.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation. Traffic is also expected to increase on 

reservation roads.

Conclusion

Alternative A would have the least land use impact 

among alternatives because of the limited number of 

exploration and production wells within the Planning 

Area. The greatest potential land use impact would be 

the ranching disturbance and displacement on the CX 

Ranch (see the Livestock Grazing section of this 

chapter). Approximately 500 acres of surface area 

would be disturbed (Table 4-56), which is less than 

0.01 percent of the total Planning Area. 

Cumulative impacts are estimated to be 

approximately 41,070 acres of disturbance from 

CBNG related and other activities within the 

Planning Area. The cumulative impacts comprise less 

than 1 percent (0.21 percent) of the entire Planning 

Area. 

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Exploration and Production

Short-term impacts of land uses during construction 

would consist of the physical intrusion by CBNG 

crews and equipment, the local generation of dust and 

noise and the limited obstruction of traffic. Longterm impacts include loss of existing land use, 

increased access from roads and loss of land value. 

Some surface landowners are unaware of the severed 

mineral rights and even though compensated, would 

be displeased with the possibility of having well 

facilities located near dwellings. There are no legally 

required buffer distances between CBNG facilities 

and residential, community, or government 

dwellings. Placement of roads and well pads near 

residential, business and community dwellings may 

cause direct reduction of property values. 

TABLE 4-56 

ACRES OF LAND DISTURBANCE FOR CBNG WELL EXPLORATION, CONSTRUCTION AND

OPERATION BY ALTERNATIVE

Acres of Short-term Land Disturbance 

(Exploration and Construction)

Acres of Long-term Land 

Disturbance (Operation) Total Acres 

of 

Cumulative 

Effects1 Alternative

Number 

of Wells

Federal 

Wells

State/Private 

Wells Total

Federal 

Wells

State/Private 

Wells Total

A 675 400 1,100 1,500 0 500 500 41,070

B and D2 18,275 25,600 29,750 55,350 15,250 17,700 32,950 88,270

C2,3 18,275 32,400 37,600 70,000 22,000 25,600 47,600 109,497

E2,3 18,275 34,250 39,750 74,000 20,350 23,650 44,000 99,370

F and H2,4 18,225 26,600 29,550 55,150 15,250 17,6004 32,850 88,170

G2 6,470 9,100 10,500 19,600 5,400 6,250 11,650 20,450

1 Cumulative effects include long-term acres of disturbance from CBNG well operation (BLM, state and other) and other projects or activities 

identified in the RFD. Other projects or activities included in the cumulative effects total an additional 41,070 acres as described in the Minerals 

Appendix.

2 Ten percent of CBNG wells are predicted to be dry holes. Acres of disturbance for these wells are considered to be the same as for exploration. 

Consequently, only 90 percent of the predicted wells would result in long-term land disturbance from construction and operation. 3 The long-term direct impacts and the length of roads and corridors would be 27 percent greater for Alternatives C and E than for Alternatives B, 

D and F because transportation corridors and the use of existing disturbed lands would not be required for roads and utilities under Alternatives C 

and E.

4 Fifty fewer state wells are included for Alternatives F and H because they were predicted to occur in the three counties outside the Billings and 

Powder River RMP areas. The difference in total acres of land disturbance from these wells is small relative to the total acres of land disturbance 

from all predicted wells.
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Although there may be no statute that covers buffer 

distances, State of Montana oil and gas leases include 

a minimum buffer distance of 200 feet. Reasonable 

additional buffers can be added as needed at the time 

of site-specific operating plan review, including 

movement up to 656 feet on Federal leases.

Impacts from placement of roads, utility lines, 

pipelines and well pads around communities may 

cause loss of future community development 

opportunities. These uses displace other surface uses 

like residential development and location of public 

parks and schools. There are safety and liability 

concerns.

Although private landowners and state land 

managing agencies would help decide road routes on 

their lands, as described in the Mitigation section, 

they would likely want to maintain some roads that 

benefit existing or future uses. 

The increase in average daily traffic of U.S., 

interstate and state highways by action alternatives 

would be minor and is not expected to decrease their 

designed level of service within the CBNG Planning 

Area. Increased highway average daily traffic over 

the 20-year life of the project would be largely from 

increases in demographics. 

County roads in some portions of the Planning Area

would receive substantial CBNG exploration and 

development traffic volumes. This large influx of 

CBNG-related traffic on some isolated county and 

local roads would increase their associated road 

maintenance cost.

Lease operators would discuss compensation with 

county and local road and bridge departments when 

CBNG-related traffic has caused increased road 

maintenance cost. There may be times when an 

operator or a group of operators may choose to 

provide maintenance for a particular road. 

Short-term exploration impacts to farming include 

seasonal loss of crops during construction, 

interference with irrigation patterns and increased 

introduction of noxious weeds.

Cropland area converted to production well pads and 

roads would be lost for the up to 20-year life of the 

project. Four percent of wells in the Powder River

RMP area and 8 percent of the wells in the Billings 

RMP area would occur in cropland soils. Specific 

long-term impacts include land displacement; 

alteration of existing flood and center pivot irrigation 

systems; modification of farming operations near and 

around well pads and access roads; potential for 

proliferation of noxious weeds; surface and 

groundwater quality losses; farming operations that 

are no longer commercially viable at certain 

locations; economic losses associated with all of the 

above; and lower land values.

Direct impacts on commercial woodlands would be 

caused by the immediate harvest of timber in ROWs 

and well pad sites and the loss of timber growth in 

these areas during the life of production and time of 

regrowth to merchantable trees. The income loss for 

the tree growth loss is reflective of time to grow 

merchantable trees, which is 50 to 100 years after 

reclamation of ROWs and pad sites. New roads on 

public forest lands may become part of the existing 

road system and their ROWs would be a permanent 

loss of timber production. The increased use of fourwheel-drive and all-terrain vehicles would allow 

other vehicles to have extensive access once a route 

is established.

Roads from CBNG development and CBNG-related 

motorized activity may create conflict with timber 

cruising, logging and hauling activities of an active 

timber sale. CBNG-related traffic could increase 

traffic hazards with log-hauling trucks unless road 

use coordination occurs. 

Indirect impacts from land clearing include wood fuel 

loading, introduction of noxious weeds; increases in 

insect population from slash buildup; and increased 

access for forest and fire management. CBNGconstructed roads may not always be located in the 

best area for managing forest resources.

Abandonment

On federal and state lands, the access plan would 

create fewer two-track trails and roads than other 

development alternatives. Utility reclamation would 

occur with road reclamation because they are located 

in the same corridor. Public access would be 

restricted over the life of the CBNG productions on 

the road network and would not become part of the 

permanent public access network. On private lands, 

road abandonment would be highly variable because 

each landowner agreement could be different. 

Regeneration time of timber to commercial size after 

CBNG activities or other related land use would 

likely be 50 to 100 years. Road obliteration would 

include re-contouring the landscape and planting tree 

seedlings appropriate to the forest site. 

Damage from a fire related to CBNG activities would 

be the responsibility of the operator. Liability of fire 

is detailed in Statute 50-63-103 MCA. 
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Crow Reservation

If there were no CBNG development on tribal Lands, 

then impacts on the reservation, other than CBNG

related traffic discussed above, would be minimal. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under Alternative B.

Conclusion

Alternative B would have fourth smallest impact to 

present land use of the seven development 

alternatives (B, D, C, E, F, G & H). For example, the 

required use of a transportation corridor for both road 

and utility lines in a one-way pattern reduces the 

direct surface disturbance by an estimated one-third 

compared to a grid pattern, multiple corridor 

approach. 

Common land use impacts from roads, pads, 

pipelines and utility lines include direct loss of 

agriculture, timber, grazing, recreation and wildlife 

habitat and increased potential of wildfire. Indirect 

impacts include limited road access; dust, noise and

reduced property values; and increased local road 

maintenance cost, production, water storage and

ground injection, which reduces the potential direct 

and indirect impacts to other surface land uses. 

Residual benefits of the road networks created for 

CBNG development include increased access for 

fighting fires and create fuel breaks.

Most direct and indirect impacts are mitigated 

through reclamation and financial compensation. 

Although minimal impacts due to dust may occur, 

dust abatement measures would be actively employed 

to minimize impacts to air quality as well as land 

resources. Surface owner agreements would be used 

to prevent avoidable impacts to residents and 

communities. Impacts minimized by surface owner 

agreements include, but are not limited to, disruption 

to irrigation facilities, placement of roads, pipelines

and well pads. Unmitigated impacts include 

displaced, non-monetary uses like public access, fire 

hazards and noise disturbance to livestock. 

Alternative B is estimated to cause 32,950 acres of 

long-term surface disturbance (Table 4-56), which is 

less than 1 percent of the total Planning Area. 

Cumulative impacts for Alternative B include 

increased fire hazards from CBNG exploration and 

development, which are the largest potential 

cumulative economic and environmental impacts to 

future land uses. The loss of range, timber, habitat, 

dwellings, access and other impacts would not be 

recovered for a long time. However cumulative 

impacts are estimated to be 88,270 acres which is less 

than 1 percent of the entire Planning Area. 

Alternative C—Emphasize CBNG 

Development

The less stringent access plan, separate placement of 

pipelines, utility lines, lack of buffers and use of 

production water, would lead to an increase in 

surface land disturbance when compared to the other 

alternatives.

Exploration and Production

New production roads may be placed along existing 

trails or be placed in the more traditional road grid 

system, which allows multiple routes from any 

production intersection. The traditional road grid 

system used for CBNG production would create the 

highest density of roads and may increase the size of 

the public road network. On private lands, road 

placement would be a contractual agreement with the 

surface owner and roads may be left in place or 

reclaimed. 

Surface disturbance from roads, pipelines and utility 

lines is estimated to be approximately 30 percent 

greater than Alternatives B and D (see Table 2-2 in 

Chapter 2) because there are not the same road and 

utility restrictions to this alternative. Surface 

disturbance and its impact to agriculture is similar to 

Alternative B because most agriculture is on private 

lands. The potential impacts from production water 

discharges are also similar for the same reason. 

CBNG production water may have high levels of 

salinity or sodicity, which can cause negative impacts 

to agriculture with continued use. The saline level of 

the average CBNG production water is near the 

threshold for causing yield reduction. Reduction in 

yields would be expected in salinity-sensitive crops 

like alfalfa, corn and clover hay. High SAR 

production water would reduce water infiltration, 

especially in clay soils and would increase erosion. 

CBNG water with combined high SAR and low EC 

can cause notable reductions in the water infiltration 

rate of irrigated crops (ALL 2001b). Repeated 

sprinkler-applied CBNG water high in saline can 

cause salt accumulation near the soil surface and 

cause foliar damage to certain crops. Dewatering coal 

seams may lead to release of methane gas that can 

contaminate neighboring agricultural and residential 

wells (ALL 2001b). The contamination of wells is a 

possibility that cannot be estimated in either amount 

of methane per well or by proximity of a well to a 

CBNG field. Any contaminated well could be 
CHAPTER 4

Lands and Realty

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rendered unusable and if the well is within a closed 

structure, increased ventilation is required to reduce 

buildup to explosive quantities.

It must be assumed that the historic road grid system 

used for CBNG development is a worst-case scenario 

allowed under this alternative when there are no 

existing disturbances. The road grid system would 

create the densest road network and largest surface 

disturbance by providing multiple access to all the 

wells in the 80-acre well spacing proposal. 

Abandonment

Land use displacement from road disturbances would 

be an assumed 20-year loss on federal, state and

private lands as in Alternative B, except there is more 

displacement on federal and state lands with this 

alternative. Land use displacement on private lands 

would have varying degrees of reclamation based on 

whether road placements benefit long-term private 

operations. 

There is limited access to many small federal land 

parcels within the Planning Area. CBNG lease 

operators would create roads to these parcels and 

increase access and potential public use of the federal 

parcels. Neighboring private owners who have 

contributed access to the federal and state parcels 

may incur increased trespass problems similar to 

Alternatives B and D. 

Crow Reservation

If there were no CBNG development on tribal lands, 

then impacts on the reservation, other than increased 

CBNG-related trespass problems discussed above, 

would be minimal. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation 

would be similar to those described for the Crow 

Reservation under Alternative C.

Conclusion

CBNG management under Alternative C would result 

in the most impacts to present land uses among the 

seven development alternatives (B, C, D, E F, G & 

H). The disturbance is estimated to be one-third 

greater than Alternatives B and D. The two main 

causes for the increased surface disturbance and land 

use displacement are from use of a traditional road 

grid system. Surface owner agreements would be 

used to minimize surface disturbance due to road 

placement.

Overall, approximately 47,600 surface acres would 

be impacted, even with the increased impacts, this 

area is less than one percent of the Planning Area. 

Cumulative impacts including the additional surface 

impacts total 109,497 acres for Alternative C. The 

increased cumulative impacts remain below 1 percent 

of the entire Planning Area. 

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Short-term transportation impacts on federal and state 

land uses would be the same as Alternative B.

However, the long-term transportation impacts would 

be greatest because road obliteration and reclamation 

might not occur under this alternative and would 

permanently displace present and future land uses. 

The roads would become part of the public 

transportation system and would increase vehicle 

access on federal lands. The existing public road 

network may receive substantial traffic during 

production, requiring increased maintenance cost by 

public agencies. The new roads on federal lands that 

are not reclaimed would become the maintenance 

responsibility of the corresponding public agency. 

Crow Reservation

Impacts on the Crow Reservation would be primarily 

the result of vehicle trespassing. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under Alternative D.

Conclusion

Alternative D has the same short-term transportation 

impacts as Alternative B but has the greatest longterm land use displacement impacts from the created 

permanent roads. The types of land use displacement 

with this alternative are the same as other 

development alternatives. Surface owner agreements 

would be used to minimize impacts due to land use 

displacement.

Most direct and indirect impacts are mitigated 

through reclamation and financial compensation. 

Unmitigated impacts include public access, fire 

hazards and disturbance to livestock. Total permanent 

surface impacts and cumulative impacts are estimated 

to be the same as alternative B. 
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Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Exploration and Production

The type of impacts from roads, pipelines and utility 

lines in Alternative E are the same as those described 

in Alternative B. The extent of these impacts would 

be the same as described in Alternative C. This 

alternative, like Alternative C, would not require 

transportation corridors for the placement of roads, 

utility lines and pipelines. Existing disturbances 

would be used as much as possible for utility access. 

Management features of Alternative E include 

burying power lines in certain locations and 

requirements of a project plan to minimize impacts. 

Land use displacement from road disturbances would 

be up to 20-years on federal, state and private lands 

as with Alternatives B and C. CBNG lease operators 

would create roads to small federal and state parcels 

never before road accessible to the public. Motorized 

trespass would be enhanced as a result of the 

increased road network on federal, state and private 

lands from CBNG-related exploration and 

development.

Agricultural-related impacts would be the same as 

those described in Alternative B.

CBNG activities increase the likelihood of fire. Road 

networks created for CBNG development would 

increase access for fighting fires.

Abandonment

Abandonment of roads, utility lines and powerlines 

would be the same as described in Alternative C.

On private lands, road abandonment would be highly 

variable as with the other alternatives because each 

landowner agreement would be different.

Liability of fire is detailed in Statute 50-63-103 

Montana Code Annotated.

Conclusion

CBNG operators would be required to submit a 

Project Plan when the proposed development for an 

area would exceed one well per 640 acres.

The type of impacts from roads, pipeline and utility 

lines in Alternative E are the same as those described 

in Alternative B. The extent of impacts would be the 

same as described in Alternative C. This alternative, 

like Alternative C, would not require transportation 

corridors for the placement or roads, utility lines and

pipelines. Existing disturbances would be used as 

much as possible.

New roads would remain open or closed at the 

surface owner’s discretion. Roads would be 

reclaimed upon abandonment.

There would be no degradation of watersheds from 

release of production water. A Water Management 

Plan would be required for every exploration Permit 

to Drill. First priority for discharged water would be 

for beneficial uses.

The potential for fire hazard is the same as 

Alternatives B, C and D. Surface disturbances 

associated with Alternative E would impact 

approximately 44,000 acres long term (Table 4-56). 

This is equivalent to less than one percent of the 

Planning Area. The total area of cumulative impacts, 

including surface disturbances from additional 

activities described previously, is estimated to be 

99,370 acres. This total area is less than 1 percent of 

the entire Planning Area. 

Alternative F—High Range Phased CBNG 

Development

Exploration and Production

The types of impacts from roads, pipelines and utility 

lines are the same as those described for Alternatives 

B and D (Table 4-56). Development would likely 

have less surface land disturbance, decreased road 

construction and decreased long-term use due to the 

following: restrictions on the number of federal 

permit applications approved annually; consideration 

of cumulative effects within each 4th Order 

watershed and crucial habitat polygons during POD 

development; and the possible discharge of some 

untreated federal CBNG water to surface water 

instead of storage or treatment and conveyance. 

Watershed protection would likely include road 

obliteration and reclamation to mitigate sensitive 

wildlife resources, particularly sage-grouse. Thus, 

this alternative is expected to result in a decrease in 

open roads and a decrease in road maintenance costs. 

More roads are expected to be reclaimed under this 

alternative.

However, over the entire development period, it is 

expected that the total area disturbed would be most 

similar to, but slightly less than, Alternatives B and 

D, including exploration, construction, operation and

cumulative effects. Thus, cumulative effects over the 

entire time period would be similar to Alternatives B, 

D and F (see Table 4-56). The difference between 
CHAPTER 4

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Alternative F and Alternatives B and D is primarily 

the phasing of approved activities rather than the 

amount and extent of activities. Alternative F would 

result in a more even level of disturbance activity 

over the development period. With this phasing, it is 

likely that slightly less disturbance would occur than 

Alternatives B and D. 

The type of agricultural effects would be similar to 

Alternative B, although the impacts would be 

distributed differently over the development period 

due to phasing of CBNG development. 

CBNG activities would continue to increase the 

likelihood of fire, while road networks created for 

CBNG development would help to increase access

for fighting fires.

Abandonment

Land use displacement from road disturbance is 

expected to be less considering the extent of 

displacement in a given year but with a similar total 

amount as Alternatives B and D over the 

development period. This is due to a phased 

development approach of well development and 

associated road construction, use, operation and

maintenance.

Crow Reservation

For development proposed within 5 miles of the 

Crow Reservation, Alternative F would require the 

operator to include site-specific groundwater and air 

quality analyses in the POD to demonstrate no impact 

to reservation resources. Additionally, groundwater 

and air quality monitoring may be required during 

development to ensure that no impacts occur. As a 

result of this additional level of evaluation, an 

operator would likely be more cautious regarding its 

level of disturbance and the tribe would likely have 

increased opportunity to comment beyond 

consultation required under all alternatives. Potential 

mitigation measures reached in agreement with the 

tribe could include minimizing the amount of surface 

area disturbance and the extent of new road 

construction. The tribe could also request increased 

road abandonment and vegetation restoration 

following surface disturbance activities, all of which 

could decrease the overall extent of land disturbance.

Northern Cheyenne Reservation

Land use effects to the Northern Cheyenne 

Reservation would be similar as described above for 

the Crow Reservation. 

Conclusion

Although the potential amount of surface and road 

disturbance for Alternative F is similar to 

Alternatives B and D, surface area disturbance and 

road construction associated with federal CBNG 

development would occur in different amounts and 

within different areas over the development period 

based on the phasing and watershed-level limitations 

that are part of this alternative. 

With the potential to limit land disturbance and road 

construction based on watershed-level analysis, the 

presence of sensitive wildlife habitat and/or the 

location of development on or adjacent to Northern 

Cheyenne and Crow reservation lands, this 

alternative has the potential to have less land use 

impacts than Alternatives B, C, D and E. However, 

disturbance to specific areas over the development

period is difficult to predict due to the decision to 

continue to reevaluate development in each 

watershed over the planning development period and 

the adaptive management approach that would be 

used to determine future location and extent of 

CBNG development. 

Alternative G—Low Range Phased CBNG 

Development

Exploration and Production

The extent of impacts from roads, pipelines and

utility lines would be about 65 percent less than 

Alternative F (Table 4-56). Effects would be phased 

over time and would have less surface land 

disturbance and decreased road construction and 

long-term use than the other development 

alternatives. Watershed protection would likely 

include road obliteration and reclamation in the 

interest of mitigating sensitive wildlife resources, 

particularly sage-grouse, which is sensitive to human 

disturbance. Thus, this alternative is expected to 

result in the lowest open road mileage and least road 

maintenance costs among all action alternatives. The 

maximum amount of open roads is expected to be

reclaimed under this alternative.

Over the entire development period, it is expected 

that Alternative G would result in greater land 

disturbance than Alternative A (no action) but less 

land disturbance than the other development 

alternatives (Alternatives B, C, D, E, F and H). 

The type of agricultural effects would be similar to 

Alternative B, although the impacts would be 

distributed differently over the development period 

due to phasing of development. 
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CBNG activities would continue to increase the 

likelihood of fire, while road networks created for 

CBNG development would help to increase access

for fighting fires.

Abandonment

Land use displacement from road disturbance is 

expected to be the least amount in any given year and 

over the development period compared to the other 

action alternatives. This is due to the lowest number 

of new wells planned for construction, operation and

maintenance, which would result in the lowest 

amount of road mileage. 

Crow Reservation

Similar to Alternative F, Alternative G would have 

the least effect on Crow Reservation lands because 

this alternative would also require consultation with 

the Crow Tribe to minimize overall CBNG 

development effects. Mitigation measures reached in 

agreement with the Crow Tribe could include 

minimizing the amount of surface area disturbed and 

the extent of new road construction. The Crow Tribe

could also request increased road abandonment and 

vegetation restoration following surface disturbance 

activities, all of which could decrease the overall 

extent of land disturbance.

Northern Cheyenne Reservation

Impacts on Northern Cheyenne tribal lands would be 

similar to that described under the Crow Reservation. 

Conclusion

Alternative G would result in the lowest number of 

new wells and the least amount of total disturbed 

acres among the development alternatives. Other 

development effects of Alternative G would be 

similar to Alternative F since both alternatives would 

use a phased development approach. 

Similar to Alternative F, Alternative G would limit 

land disturbance and road construction based on a 

watershed-level analysis, the presence of sensitive 

wildlife habitat and/or the location of development on 

or adjacent to Northern Cheyenne and Crow 

reservation lands. However, disturbance to specific 

areas over the development period is difficult to 

predict due to the decision to continue to reevaluate 

development in each watershed over the development 

period and the adaptive management approach that 

would be used to determine future locations and 

extents of CBNG development. 

Alternative H—Preferred Alternative - 

Multiple Screens

Exploration and Production

The types of impacts from roads, pipelines and utility 

lines are the same as those described for Alternatives 

B, D and F (Table 4-56). Development would likely 

have less surface land disturbance and decreased road 

construction and long-term use through the use of 

four resource screens. Similar to Alternative F, 

mitigation would likely include road obliteration and 

reclamation in the interest of mitigating sensitive 

wildlife resources, particularly sage-grouse, as well 

as water and air resources. Additionally, long-term 

stakeholder planning within watersheds would likely 

result in consolidation of infrastructure through 

coordination and sharing between stakeholders. Thus, 

this alternative is expected to result in a similar level 

of open and closed roads, as well as decreased road 

maintenance costs as Alternative F. 

Over the entire development period, it is expected 

that the total area disturbed would be most similar to

Alternative F, including exploration, construction, 

operation and cumulative effects. The difference 

between Alternative H and Alternative F is how 

sensitive resources would be treated (water, wildlife

and air), although cumulative land use effects are 

expected to be similar. Although Alternative H does 

not include an annual limit on APDs, the rate of 

development is expected to be similar to Alternative 

F due to the level of planning and environmental 

review necessary to address the four resource 

screens. 

The type of agricultural effects would be similar to 

Alternatives B and F, although the impacts would be 

distributed over the development period more like 

Alternative F due to application of the four resource 

screens to proposed CBNG development. 

CBNG activities would continue to increase the 

likelihood of fire, while road networks created for 

CBNG development would help to increase access

for fighting fires.

Abandonment

Land use displacement from road disturbance is 

expected to be less, considering the extent of 

displacement in a given year, but with a similar total 

amount as Alternatives B, D and F over the 

development period. This is due to the level of 

planning necessary to address the four resource 

screens for proposed well development and 

associated road construction, use, operation and

maintenance.
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Crow Reservation

Alternative H includes a Native American Concerns 

screen, which would likely result in less impacts to 

the Crow Reservation and its resources than 

Alternatives B through F. For any POD submitted 

proposing activities within 5 miles of the reservation, 

Alternative H would require the operator to 

demonstrate in the POD that no impacts would occur 

to reservation resources, as well as monitoring during 

operations to ensure that no impacts occur (similar to 

Alternative F). Additionally, operators would be 

required to consult with affected tribes when 

proposing development in the vicinity of traditional 

cultural properties. Consequently, an operator would 

likely be more cautious on its level of disturbance

and the tribe would likely have an increased 

opportunity to comment, although consultation with 

the tribe would occur under all alternatives. Potential 

mitigation measures reached in agreement with the 

tribe could include minimizing the amount of surface 

area disturbance and the extent of new road 

construction. The tribe could also request increased 

road abandonment and vegetation restoration 

following surface disturbance activities, all of which 

could decrease the overall extent of land disturbance.

Northern Cheyenne Reservation

Land use effects to the Northern Cheyenne 

Reservation would be similar as described above for 

the Crow Reservation. 

Conclusion

The potential amount of surface and road disturbance 

for Alternative H is similar to Alternatives B, D and

F. For alternative H, surface area disturbance and 

road construction associated with federal CBNG 

development would occur in different amounts and 

within different areas over the development period 

based on the resource screens and watershed-level 

analysis that are part of this alternative. 

This alternative has the potential to have less land use 

impacts than Alternatives B, C, D and E, but similar 

effects as Alternative F. Alternative H has the 

potential to limit land disturbance and road 

construction based on a screening level analysis for 

air and water, the presence of sensitive wildlife 

habitat and/or the location of development on or 

adjacent to Northern Cheyenne and Crow reservation

lands and traditional cultural properties, However, 

disturbance to specific areas over the development

period is difficult to predict due to the decision to 

continue to reevaluate development in each 

watershed over the planning development period and 

the adaptive management approach that would be 

used to determine future location and extent of 

CBNG development. 
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Livestock Grazing

Livestock Grazing

AUM is equal to the amount of forage required to support one 

cow and her calf or 5 sheep for one month.

Within the FSEIS Planning Area, BLM-administered surfaces 

have an estimated 1,389,908 acres of land classified as grazing, 

capable of supporting 259,554 AUMs. 

Alternative A

No Action (Existing CBNG Management)

• Exploration wells located within BLM-permitted 

rangelands would result in the temporary loss of 

69 AUMs

• State:

− The exploration wells and production wells located 

at CX Ranch would result in a maximum 

construction loss of 272 AUMs on state and private 

rangelands. 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Exploration wells would result in the temporary loss of 

413 AUMs (BLM 163, State 250).

• Production wells would result in a maximum construction 

loss of 11,960 AUMs (BLM 4,770, State 7,190).

Alternative C

Emphasize CBNG Development

• Impacts to livestock grazing would be similar to but 

slightly greater than those in Alternative B due to the 

discharge of untreated production water on to the ground 

resulting in increased erosion 

• CBNG discharge water could be used for livestock 

watering.

• Increased erosion could result in increased surface 

disturbance, which could lead to disrupted grazing 

patterns, undermined fencing and reduced forage.

• A decrease in forage could occur if discharged produced 

water is too high in saline content; and possible effects to 

livestock if produced water is to unsuitable quality for 

stock watering.

Alternative D 

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Impacts would be similar to Alternative B with some 

exceptions: disturbed acreage would increase due to the 

piping of discharge water to the nearest disposal point. 

There would be less forage losses than Alternative B.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Impacts to livestock grazing would be similar to 

Alternative B. 

• Suitable CBNG discharge water could be used for 

livestock watering.

• Managed irrigation of produced water would promote 

growth of vegetation.

Alternative F

Phased Development Multiple Screens (High Range)

• Impacts to livestock grazing would be similar to 

Alternative B and phased in after watershed analysis. 

• Water Management Plans for federal CBNG wells would 

incorporate results and requirements identified by 

watershed-level analysis

• Impacts from federal CBNG development would occur 

primarily in the latter years of the planning period, 

generally following after state and private development. 

Alternative G

Phased Development Multiple Screens (Low Range)

• Impacts would be similar to Alternative F but the land 

disturbance area would be 65 percent less.

Alternative H 

Preferred Alternative - Multiple Screens

• Impacts to livestock grazing would be similar to 

Alternative B. 

• CBNG PODs would be screened for four resources, of 

which water management would have the most potential 

effects on livestock grazing.

• Water Management Plans for federal CBNG wells would 

incorporate results and requirements identified by 

watershed-level analysis. 

Livestock grazing and petroleum development would 

be generally compatible because exploration activity 

would be temporary and operational activities require a 

small area for equipment. Livestock grazing on 

rangeland would continue during CBNG and 

conventional oil and gas development.

Assumptions

Affected acres and animal unit months (AUMs) were 

calculated assuming all CBNG activity would be 

located on grazing lands. AUM losses were predicted 

separately for the two BLM RMPs and the state 

because of differences in permits and land grazing 

capacities. The analysis is focused on the Planning 

Area, but applies to similar areas throughout Montana. 

It is assumed that existing roads and fence crossings 

would be used for oil and gas operations as much as 

possible.

Impacts from Management Common 

to All Alternatives

Impacts on rangeland would occur from the loss of 

vegetation for livestock grazing; the disruption to 

livestock management practices; and loss of grazing 

capacity from construction of well pads and roads. 

Each well would present its own set of unique 

circumstances that would be mitigated to minimize 

impacts. With the exception of minimal short-term 
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forage loss, these impacts would only last as long as 

construction activities were ongoing. Controlling 

livestock movement by maintaining fence line integrity 

would be used to preserve efficient livestock and range 

management. The construction of roads and pipelines 

would bisect fences, which would require placement 

and maintenance of cattleguards and gates. The current 

development of oil and gas and CBNG on state land 

would require installation of cattleguards on fence

lines to prevent livestock escape. The impacts of oil 

and gas development would result in the loss of about 

833 AUMs on BLM-Administered surface in the 

Billings RMP, 830 AUMs in the Powder River RMP

and 359 AUMs on state-permitted rangelands. These 

losses would be reduced to a total of 735 AUMs during 

the production phase of oil and gas activities.

While roads, trails and well pads would block 

traditional cattle trails, this network of new roads 

would provide livestock producers with improved 

access to remote livestock facilities and grazing areas. 

However, road systems would interfere with livestock 

dispersal and cause decreased forage efficiency 

because cattle tend to congregate and travel along 

roads. The relatively high volumes of exploration 

vehicle traffic would present a hazard to livestock. 

Heavy traffic on temporary access roads would 

increase the risk of collision with stock, resulting in 

injury or death of the animals. Airborne dust stirred up 

by heavy exploration vehicles would settle on forage 

along the road. The dust would affect the palatability 

of grass and forbs up to 1/4 mile from the road. 

Livestock forage could be killed by accidental spills of 

crude oil, high saline-produced water, or drilling fluid.

Areas of soil disturbance, such as results from 

construction, may experience an influx of noxious 

weeds. Noxious weeds reduce rangeland value to 

livestock by displacing preferred forage species. Severe 

infestations would result if weeds are not controlled, 

decreasing rangeland capacity for grazing. Additionally, 

some weed species are poisonous to livestock, causing 

illness, internal injury, or death when ingested.

Loss of AUMs may be reduced somewhat through the 

beneficial use of produced water, primarily in poorly 

watered pastures and secondary rangelands. Also, there 

may be opportunities for surface owners upon well 

abandonment, to take ownership of CBNG wells and 

power sources for livestock watering purposes. 

Activities other than those associated with CBNG 

production are expected to result in additional 

disturbances to livestock grazing. These activities 

include conventional oil and gas, active coal mines, 

fires, highway projects, power plants and the proposed 

Tongue River Railroad.

The proposed Tongue River Railroad would extend 

between 17.3 and 29.4 miles, traversing grazing lands 

bordering the valley bottom land. The ROW would 

include between 447 and 636 acres, most of which is 

agricultural rangeland (411 to 599 acres). The entire 

ROW would be fenced to keep domestic livestock off 

the tracks and livestock passes would be installed to 

allow continued movement between pastures. However 

local ranchers are concerned livestock may be reluctant 

to use the passes, especially those used infrequently

and this may increase the time required to herd 

livestock between pastures. Operations may also 

increase the potential for railroad-caused range fires

(Surface Transportation Board 2004). 

Impacts from Management Specific to 

Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

Exploration wells located on BLM-permitted 

rangelands would result in the temporary loss of 30 

AUMs for the Billings RMP rangeland and 39 AUMs 

for the Powder River RMP rangeland. There would be 

no production activities in BLM planning areas under 

this alternative and, therefore, no impacts from 

production. State-permitted exploration and production 

wells located at CX Ranch would result in a loss of 

272 AUMs. Revegetating parts of the well pads during 

production would reduce the losses to 194 AUMs. 

Crow Reservation

Impacts on the Crow Reservation would be the same as 

described in general for Alternative A. If there were no 

CBNG development on tribal Lands, then there are 

expected to be minimal, if any, impacts on livestock 

grazing on the reservation. If there is CBNG 

development on the reservation, then reductions in

AUMs could occur.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described for the Crow Reservation. 

Conclusion

During the next 20 years, disturbances from CBNG

development, conventional oil and gas development

and other projects considered under the cumulative 

effects analysis would result in the loss of about 

863 AUMs in the Billings RMP, 869 AUMs in the 

Powder River RMP and 631 AUMs on state-permitted

and private rangelands. These losses would be reduced 
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to a total of 929 AUMs during the production phase of 

CBNG and conventional oil and gas activities. After 

CBNG production ceases, the lands would be 

reclaimed. Revegetated areas would be available for

livestock grazing. 

Alternative B—Emphasize Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

Alternative B considers expanded development of 

CBNG resources. Table 4-57 presents the predicted 

AUMs that would be lost from exploration, 

construction and production on both BLM and state

grazing lands. Losses from exploration would be 

mostly temporary (less than 5 years) and would be 

reclaimed after exploration activities cease. 

Revegetating parts of the well pads during production 

would be used to reduce construction losses to those 

shown below under operation losses.

Impacts on livestock grazing would be reduced under 

this alternative through the requirement of 

transportation corridors, using multiple completions 

per well bore and directional drilling, injecting 

produced water instead of storing on-site in 

impoundments and rehabilitating new roads at the end 

of the well lifetime. All of these would help to 

minimize the area of surface disturbances shown in 

Table 4-57 by up to 35 percent during construction and 

40 percent during production, thus reducing the 

number of AUMs lost. 

Crow Reservation

If there were no CBNG development on tribal Lands, 

then there are expected to be minimal, if any, impacts 

on livestock grazing on the reservation. If there is 

CBNG development on the reservation, then 

reductions in AUMs would occur.

Northern Cheyenne Reservation

If there were no CBNG development on tribal Lands, 

then there are expected to be minimal, if any, impacts 

on livestock grazing on the reservation. If there is 

CBNG development on the reservation, then 

reductions in AUMs would occur.

Conclusion

During the next 20 years, disturbances from CBNG 

development on state, BLM, Native American and

USFS lands; along with the cumulative effects of other 

projects would result in the loss of about 18,500 

AUMs. These AUM losses would be partially 

recovered during the production phase of CBNG and 

oil and gas activities and after production ceases and 

the lands are reclaimed. The requirement for 

transportation corridors, injection of produced water 

(less land needed for impoundments) and multiple use

of drilling pads would help to minimize livestock 

grazing losses up to 35 or 40 percent.

Alternative C—Emphasize CBNG

Development

Impacts on livestock grazing would be similar to 

Alternative B with the following exceptions: 

transportation corridors and collocation of wells would 

not be required, thereby increasing the number of 

disturbed acres and AUMs lost compared to 

Alternative B (see Table 4-57); suitable CBNG 

discharge water could be used for livestock watering 

reducing the amount discharged; and the discharge of 

produced water to the surface would increase erosion

and cause increased surface disturbance to livestock. 

Other impacts would include the possibility of an 

increase of noxious weeds and a decrease in forage 

material if produced water that is too high in saline 

content is discharged on the land surface and possible 

health effects if livestock consume produced water that 

is unacceptable (ALL 2001b).

TABLE 4-57 

NUMBER OF PREDICTED ANIMAL UNIT MONTHS (AUMS) LOST TO EXPLORATION, 

CONSTRUCTION AND PRODUCTION FOR ALTERNATIVE B

AUMs Lost to Exploration AUMs Lost to Construction AUMs Lost to Operation 

Billings RMP 11 340 209

Powder River RMP 152 4,430 2,275

BLM Sub-total 163 4,770 2,484

State/Private Lands 250 7,190 4,420

Total 413 11,960 6,904
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Generally, water is acceptable for livestock if the 

TDS is lower than 10,000 mg/l and the EC is less 

than 16,000 μS/cm. Some CBNG water has also been 

found to exceed standards for fluoride (2 mg/l) and 

aluminum (0.2 mg/l) (ALL 2001b). Discharging 

untreated CBNG-produced water on the ground 

surface at the well pad would lead to increased 

localized soil erosion and gullying, which could also 

lead to disrupted grazing patterns, undermined 

fencing and reduced forage. 

Crow Reservation

Off-reservation development will not affect onReservation livestock grazing practices. The 

discharge of untreated CBNG production water on 

ground surfaces within the reservation boundary 

(from development adjacent to the reservation) could 

lead to localized soil erosion, which could result in 

the creation of gullies, fence post disturbance and

limited vegetation loss. 

Northern Cheyenne Reservation

Off-reservation development will not affect onReservation livestock grazing practices. The 

discharge of untreated CBNG production water on 

ground surfaces within the reservation boundary 

(from development adjacent to the reservation) could 

lead to localized soil erosion, which could result in 

the creation of gullies, fence post disturbance and

limited vegetation loss.

Conclusion

Cumulative impacts would be similar to 

Alternative B with some exceptions. The surface 

disturbance could be greater since transportation 

corridors and collocated wells are not required. 

Surface discharge of untreated produced water could 

result in increased forage loss, erosion, gullying, 

grazing pattern disruptions and fencing undermining. 

Forage losses could be permanent because of soil 

sterilization by saline water applications. This 

amount would vary depending on the quality and 

quantity of water discharged. Watering livestock 

represents only a small portion of the estimated 20 

percent beneficial reuse assumed under this 

alternative, but would still result in a small amount of 

impacts reduction to the other resources. 

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Impacts on livestock grazing would be similar to 

Alternative C with the following exceptions: impacts 

from drilling and collocation of wells would be the 

same as Alternative B; transportation corridor and 

road impacts would be similar to Alternative B; 

discharged CBNG-produced water would be treated 

and not discharged directly at the well site; and there 

would be a reduction to forage losses from increased 

managed irrigation of produced water through 

irrigation applications. This would be a favorable 

impact from having more treated water available in 

the winter and arid months available for livestock 

watering and irrigation of grazing lands. Mitigation 

measures would be similar to Alternative B.

Crow Reservation

Off-reservation development will not affect onReservation livestock grazing practices. 

Northern Cheyenne Reservation

Off-reservation development will not affect onReservation livestock grazing practices. 

Conclusion

Cumulative impacts would be similar to 

Alternative C with some exceptions: impacts from 

drilling and co-location of wells would be the same 

as Alternative B; transportation corridor and road 

impacts would be similar to Alternative B; there 

would be a reduction to forage losses from increased 

managed irrigation of produced water; and there 

would be less soil and forage loss from erosion of 

soils.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Impacts on livestock grazing would be similar to 

Alternative B with the following exceptions: 

transportation corridors and co-location of wells 

would not be required, thereby increasing the number 

of disturbed acres and AUMs lost compared to 

Alternative B (see Table 4-57); suitable CBNG

discharge water could be used for livestock watering 

reducing the amount discharged; Water Management 

Plans would be designed on a site-specific basis so no 
CHAPTER 4

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degradation would occur to water quality or to 

beneficial use. Such uses could include livestock 

watering and irrigation (benefits for livestock). 

Mitigation measures would be similar to 

Alternative B.

Crow Reservation

Off-reservation development will not affect onReservation livestock grazing practices. 

Northern Cheyenne Reservation

Off-reservation development will not affect onReservation livestock grazing practices. 

Conclusion

Cumulative impacts would be similar to 

Alternative B with some exceptions. The surface 

disturbance could be greater since transportation 

corridors and co-located wells are not required. There 

would be less soil and forage loss from erosion of 

soils. Beneficial use of produced water by watering 

livestock would reduce, by a small amount, the 

impacts to other resources.

Alternative F—Phased Development 

Multiple Screens (High Range)

Impacts on livestock grazing would be similar to 

Alternative B with the following exceptions: surface 

disturbance would be less since transportation 

corridors would not be utilized fully (but subject to

watershed-level analysis), CBNG-produced water 

would be managed on a watershed basis and sitespecific Water Management Plans would be designed 

so that no degradation would occur to water quality 

or to beneficial uses, such as livestock water; and 

CBNG production on BLM-administered surfaces 

would be limited on an annual and watershed basis, 

resulting in impacts being distributed differently over 

time and among watersheds. Development of federal 

CBNG wells would occur primarily in the latter years 

of the planning period, generally following state and 

private development, but subject to annual and 

watershed-specific development limits.

Crow Reservation

Off-reservation development will not affect onReservation livestock grazing practices. 

Northern Cheyenne Reservation

Off-reservation development will not affect onReservation livestock grazing practices. 

Conclusion

Cumulative impacts would be similar to 

Alternative B with some exceptions. The surface 

disturbance potentially could be less since use of 

existing transportation corridors or less new road 

construction may be required as a result of 

watershed-level analysis. Water Management Plans 

for federal CBNG wells would incorporate results 

and requirements identified by watershed-level 

analysis, thereby potentially increasing beneficial 

uses of discharge water, which could include 

livestock watering. Impacts from federal CBNG 

development would occur primarily in the latter years 

of the planning period, generally following after state 

and private development, but subject to annual and 

watershed-specific limits.

Alternative G—Phased Development 

Multiple Screens (Low Range)

The extent of land disturbance from roads, pipelines

and utility lines would be about 65 percent less than 

Alternative F. Effects to livestock grazing would 

likely be similarly less than Alternative F overall but 

would vary by watershed. Effects would be phased 

over time and would have less surface land 

disturbance and decreased road construction and 

long-term use than the other action alternatives. Thus, 

Alternative G is expected to result in the least effect 

on livestock grazing of the action alternatives over 

the entire planning period. 

Crow Reservation

Impacts on Crow Reservation lands would be similar 

to those described for Alternatives B, D and F. 

Northern Cheyenne Reservation

Similar to Alternative F, Alternative G would have 

the least effect on livestock grazing on Northern 

Cheyenne Reservation lands. 

Conclusion

The cumulative effects of Alternative G would result 

in the lowest number of new wells and the least 

amount of total disturbed acres among the action 

alternatives. Other development effects of Alternative 

G would be similar to Alternative F since both 

alternatives would result in a phased development 

approach based on watershed analysis. 

Disturbance to specific areas over the 20-year 

planning period is difficult to predict, because the 

alternative would reevaluate development in each 

watershed over the planning period by using an 

adaptive management approach to determine future 

location and extent of CBNG development. 
CHAPTER 4

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Alternative H—Preferred Alternative - 

Multiple Screens

Alternative H is similar to Alternatives B and F, 

although four resource screens would be used to 

evaluate PODs and on-going development, rather 

than applying specific annual limits on approved 

APDs. However, the rate of development is assumed 

to be similar to Alternative F. In addition to applying 

the resource screens and watershed-level analysis, 

operators would be required to follow standard

operating procedures for all CBNG development 

projects. Each POD would be developed in 

consultation with affected tribes, affected surface 

owner(s), permittees or lessees and other involved 

permitting agencies. BMPs would also be used in 

CBNG development.

As a result of the management actions stipulated for 

this alternative for crucial sage-grouse habitat areas, a 

lower level of development is anticipated to occur 

over approximately 93,259 acres. This would reduce 

the number of lost AUMs from construction and 

production phases when compared to Alternatives B 

and F. Overall, the AUMs lost may be reduced by up 

to 610 during construction and 318 during operation 

phases. These figures are likely higher than what will 

occur because some level of development is likely 

within the crucial sage-grouse habitat areas.

Four resource screens would be used to develop and 

evaluate PODs: water resources, wildlife, Native 

American concerns and air resources. The water 

screen could affect livestock grazing by altering the 

surface water quality of available stock water. 

Impacts on livestock grazing would be similar to 

Alternative F, but Alternative H would have the 

benefit of additional water protection. Surface 

disturbance would be reduced by limiting 

transportation corridors through watershed-level 

analysis. CBNG-produced water would be managed 

on a watershed basis and site-specific Water 

Management Plans would be designed to prevent 

degradation of water quality or beneficial uses, such 

as livestock water. 

For each Water Management Plan, the BLM would 

establish a threshold for the volume of untreated 

water that could be discharged to surface waters from 

federal CBNG wells. These requirements would be in 

addition to the surface water quality and discharge 

volume limitations which are a part of the MPDES 

discharge permitting process.

If surface water monitoring indicates a water quality 

threshold would be exceeded, no further untreated 

discharge would be allowed from federal wells 

upstream from the monitoring station. Previously 

approved water management plans could be modified 

or rescinded if monitoring indicates unacceptable 

impacts are occurring. Water quality thresholds and 

surface water monitoring requirements are detailed in 

the Hydrology Appendix.

Produced water management plans and permits

would be approved by BLM or the appropriate 

agency in consultation with affected surface owners. 

Surface storage of produced waters would also 

require an MPDES permit issued by MDEQ. 

Impoundments proposed as part of a Water 

Management Plan would be designed and located to 

minimize or mitigate impacts on soil, water, 

vegetation and channel stability. The WMP would 

also include designs to minimize or mitigate impacts 

to the available grazing forage. Additionally, such 

impoundments may be sources of water for uses 

benefiting livestock, such as livestock watering or 

surface irrigation.

Crow Reservation

The Crow Tribe considers groundwater a critical 

resource to their tribal health and welfare. 

Groundwater is used on the reservation for stock 

watering and drinking water supplies. In response to 

these concerns, the BLM would require federal lease 

operators to protect groundwater from loss or 

degradation. For all proposed CBNG development 

within 5 miles of the Crow Reservation, the BLM 

would require site-specific groundwater analyses to 

demonstrate its protection as part of the operator’s 

POD. If the analysis indicates impairment to 

groundwater would occur, the BLM would not 

approve the APDs. BLM may require an operator to 

install groundwater monitoring wells between its

development area and the reservation to confirm 

findings of the initial analysis. Protection of 

reservation groundwater resources would prevent 

potential impacts to groundwater available for stock 

watering. Also, development near reservations may 

provide an additional source of water for beneficial 

uses on the reservation.

Northern Cheyenne Reservation

The effects to livestock grazing on the Northern 

Cheyenne Reservation would be the same as those 

for the Crow Reservation. 

Conclusion

Cumulative impacts would be similar to Alternatives 

B and F. Water Management Plans for federal CBNG 

wells would incorporate results and requirements 

identified by watershed-level analysis and the water 

resource screen, thereby potentially increasing 

beneficial uses of discharge water, which could 

include livestock water. 
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Paleontological Resources

Paleontological Resources

Paleontological resources consist of fossil-bearing rock 

formations that underlie the entire Planning Area. Fossil 

outcrops are relatively rare throughout the emphasis area, but 

know areas are protected. 

Alternative A

No Action (Existing CBNG Management)

• It is unlikely that any of the 1,500 acres disturbed during 

CBNG development activities would contain noteworthy 

paleontological resources. The 575-acre Bridger Fossil 

Area of Critical Environmental Concern (ACEC) (only 

paleontological resource) would not be disturbed. 

Alternatives B, C, D, E and F 

• Impacts would be nearly the same based on level of 

disturbance, known locations of rich fossil areas and 

distribution of geological formations with paleontological 

resources.

• There would be between 55,400 and 74,000 short term 

acres disturbed during CBNG development activities 

increasing the chance of impacts to fossil resources. 

Cumulative impacts would disturb an additional 33,400 

acres increasing the potential for impacts to fossil 

resources. 

Alternative G

Phased Development Multiple Screens (Low Range)

• Impacts would be similar to Alternative F with the 

exception that they would be reduced by approximately 65

percent due to the lower number of APDs that are 

predicted to be issued.

• There would be between 19,400 and 25,900 short term 

acres disturbed during CBNG development activities 

increasing the chance of impacts to fossil resources. 

Cumulative impacts would disturb an additional 11,700 

acres increasing the potential for impacts to fossil 

resources.

Alternative H

Preferred Alternative - Multiple Screens

• Impacts would be similar to the other expanded 

development alternatives based on level of disturbance, 

known locations of rich fossil areas and distribution of 

geological formations with paleontological resources. 

However, the consolidated planning for ROWs would 

result in decreased surface disturbances. 

• There would be between 55,400 and 74,000 short term 

acres disturbed during CBNG development activities 

increasing the chances that a minor fossil discovery would 

be made. Cumulative impacts would disturb an additional 

33,400 acres increasing the likelihood of additional fossil 

discoveries. Should no drilling occur within crucial sagegrouse habitat areas, the cumulative impacts to 

paleontological resources will be less than the other 

alternatives.

Assumptions

Surface occupancy is prohibited within designated 

paleontological sites on BLM-administered minerals

in the Planning Area. A modification or waiver may 

be applied for as mentioned for the Cultural Resource

section. Provided the paleontological resource values 

can be protected or undesirable impacts mitigated, 

the exception would be granted.

The collection of vertebrate paleontological remains 

on BLM-administered surface would be done under a 

valid paleontological resources use permit and that 

reasonable, non commercial collections of 

invertebrate fossils and fossil plants would be 

allowed under 43 CFR 8365.1. The collection of 

petrified wood would be allowed under the terms of 

43 CFR 3622.

Impacts from Management Common 

to All Alternatives

Impacts would occur if paleontological resources 

were encountered unexpectedly during surface 

disturbance activities. 

The construction of the TRR would not disturb any 

known paleontological resources in the rocks or soils 

that exist within the alignment ROW. Construction 

could result in potential impact on currently unknown 

paleontological resources. Paleontological localities 

would be identified during detailed pedestrian 

surveys of the alignment as required in the Surface 

Transportation Board’s programmatic mitigation

agreement. If any paleontological resources are 

located during surveys, mitigation measures would be 

carried out that include collection and curation of 

scientifically significant fossils, additional sampling, 

or monitoring of excavations.

Impacts from Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG

Management)

Impacts from this alternative would be similar to 

those described in the Impacts From Management 

Common to All Alternatives section above. Other 

impacts could include vandalism and the illegal

removal of fossils by unpermitted fossil collectors 

resulting from increased accessibility to remote areas.
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Crow Reservation

There would not be impacts to paleontological 

resources on the Crow Reservation from offreservation CBNG development. 

Northern Cheyenne Reservation

There would not be impacts to paleontological 

resources on the Northern Cheyenne Reservation

from off-reservation CBNG development. 

Conclusion

Cumulative impacts would include the effects from 

CBNG development, conventional oil and gas 

development and surface coal mining activities. 

Known paleontological resources within the Planning 

Area would be protected by Section 6 of the lease 

terms. NSO stipulations applied to known 

paleontological resources would help protect those 

sites.

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Impacts from Alternative B would be similar to 

Alternative A, with some exceptions. Development 

could result in increased access to remote areas. The 

impacts of increased access could include vandalism 

or the illegal removal of fossils by unpermitted fossil 

hunters.

Crow Reservation

There are no anticipated impacts to paleontological 

resources on the Crow Reservation from offreservation CBNG development. 

Northern Cheyenne Reservation

There are no anticipated impacts to paleontological 

resources on the Northern Cheyenne Reservation

from off-reservation CBNG development. 

Conclusion

Cumulative impacts under this alternative would 

include increased CBNG development and a potential 

increase in vandalism or the illegal removal of 

fossils.

With the development of tribal CBNG resources, it is 

anticipated some reservation sites would be 

encountered that may contain important 

paleontological resources. As the tribes develop their 

own CBNG resources, it is anticipated tribal monitors 

would oversee all surface disturbing activities and, 

therefore, all significant paleontological resources 

would be protected. 

Alternative C—Emphasize CBNG

Development

Impacts would be similar to Alternative B with some 

exceptions. Under this alternative, surface 

disturbances from ROWs would result in impacts on 

paleontological resources and increased access to 

remote areas. The impacts of increased access could 

include increased vandalism and the illegal removal 

of fossils by unpermitted fossil hunters.

Crow Reservation

There are no anticipated impacts to paleontological 

resources on the Crow Reservation from offreservation CBNG development. 

Northern Cheyenne Reservation

There are no anticipated impacts to paleontological 

resources on the Northern Cheyenne Reservation

from off-reservation CBNG development. 

Conclusion

Cumulative impacts would be similar to 

Alternative B with increased surface disturbance 

from the lack of ROWs, potential vandalism or 

removal of fossils because of increased access to 

remote areas. 

The use of tribal monitors overseeing surface 

disturbing activities on the reservations during tribal

CBNG development would prevent most impacts 

from occurring to paleontological resources. 

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Impacts would be the same as described under 

Alternative B.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Impacts would be similar to Alternative C with some 

exceptions. Under this alternative, the project plan 

stipulations could decrease the amount of surface 

disturbance. Directional drilling may be performed 
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on deeper coal seams and would decrease surface 

disturbances. The potential for impacts from surface 

disturbances resulting from the placement of 

underground utilities would increase impacts to 

paleontological resources. Where significant 

paleontological resources are suspected, the 

operator’s plan will include a paleontological 

component that will address data collection and 

evaluation methods if paleontological remains are 

encountered.

Crow Reservation

There are no anticipated impacts to paleontological 

resources on the Crow Reservation from offreservation CBNG development. 

Northern Cheyenne Reservation

There are no anticipated impacts to paleontological 

resources on the Northern Cheyenne Reservation

from off-reservation CBNG development. 

Conclusion

Cumulative impacts under this alternative would be 

similar to Alternative C with the exception of the 

potential for less surface disturbances. The impacts to 

paleontological resources would be minimized. 

The use of tribal monitors overseeing all land 

disturbing activities on the reservations during tribal

CBNG development would prevent most impacts 

from occurring to paleontological resources. 

Alternative F—Phased Development 

Multiple Screens (High Range)

Under this alternative, impacts to paleontological 

resources would be similar to Alternative E with the 

exception that impacts may be less due to the 5-mile 

buffer zone for federal development around the Crow 

and Northern Cheyenne reservation boundaries.

Crow Reservation

There are no anticipated impacts to paleontological 

resources on the Crow Reservation from offreservation CBNG development. 

Northern Cheyenne Reservation

There are no anticipated impacts to paleontological 

resources on the Northern Cheyenne Reservation

from off-reservation CBNG development. 

Conclusion

Cumulative impacts under this alternative would be 

similar to Alternative E with the exception of the 

potential for less surface disturbances due to the 5-

mile buffer zone around the Crow and Northern 

Cheyenne reservation boundaries. The impacts to 

paleontological resources would be minimized. 

Alternative G—Phased Development 

Multiple Screens (Low Range)

Under this alternative, impacts to paleontological 

resources would be similar to Alternative F with the 

exception that the potential impacts to 

paleontological resources would be reduced by 

approximately 65 percent based on the fewer number 

of APDs that are predicted to be issued. Under 

Alternative G, the annual cumulative limit placed on 

federal APDs approved by BLM would be set at five 

percent (323 APDs) of the low-range number of state, 

private and federal CBNG APDs (6,470) predicted to 

be approved in the RMP areas (as identified in the 

Reasonably Foreseeable Development scenario in the 

2003 FEIS)

Crow Reservation

There are no anticipated impacts to paleontological 

resources on the Crow Reservation from offreservation CBNG development. 

Northern Cheyenne Reservation

There are no anticipated impacts to paleontological 

resources on the Northern Cheyenne Reservation

from off-reservation CBNG development. 

Conclusion

Cumulative impacts under this alternative would be 

similar to Alternative F with the exception that the 

potential impacts to paleontological resources would 

be reduced by approximately 65 percent. 

Alternative H—Preferred Alternative - 

Multiple Screens

Under this alternative, approximately 320,000 acres

could be surveyed during POD development as part 

of the cultural resource survey efforts. This surveying 

would enhance the likelihood that paleontological 

sites would be identified as part of the CBNG 

location and placement effort. Impacts to 

paleontological resources would be minimized but 

resemble those described for Alternative E. 
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The use of directional drilling may be performed on 

deeper coal seams and would decrease surface 

disturbances. The potential for impacts from surface 

disturbances resulting from the placement of 

underground utilities may increase impacts to 

paleontological resources. However under this 

alternative, surface disturbances from ROWs would 

be consolidated to reduce the amount of disturbance 

and minimize the footprint. This consolidated 

development would also reduce the amount of roads 

and marginally increase access to remote areas. The 

impacts from increased access could include 

vandalism and the illegal removal of fossils by

unpermitted fossil hunters. The need for 

paleontological inventories would be determined 

using the Potential Fossil Yield Classification System 

outlined in BLM Instruction Memorandum 2008-

2009.

Where significant paleontological resources are 

suspected, the operator’s plan will include a 

paleontological component that will address data 

collection and evaluation methods if paleontological 

remains are encountered.

Crow Reservation

There are no anticipated impacts to paleontological 

resources on the Crow Reservation from offreservation CBNG development. 

Northern Cheyenne Reservation

There are no anticipated impacts to paleontological 

resources on the Northern Cheyenne Reservation

from off-reservation CBNG development. 

Conclusion

The degree of cumulative impacts under this 

alternative would be similar to those described for 

Alternative F with the exception of the potential for 

less surface disturbances due to the consolidated 

development planning. The impacts to 

paleontological resources would be minimized.
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Recreation

Recreation

Montana’s natural features offer a variety of year-round 

recreational opportunities

Alternative A 

No Action (Existing CBNG Management)

• Minor loss of land for recreation purposes and the 

disruption to recreation activities

• Exploratory activities such as drilling and testing could 

temporarily displace game species locally

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Moderate loss of land for recreation purposes and the 

disruption to recreational activities

• Increased opportunities for access to remote areas

Alternative C

Emphasize CBNG Development

• Impacts would be similar to Alternative B with the 

exception that increased erosion could lead to a reduced 

amount of land available for recreation activities and 

could disrupt habitat for game species.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Impacts would be similar to Alternative B.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Impacts would be similar to Alternative B.

Alternative F

Phased Development Multiple Screens (High Range)

• Impacts would be similar to Alternative E.

• Impacts from federal CBNG development would occur 

differently than the other alternatives based on annual and 

watershed-based limits. 

Alternative G 

Phased Development Multiple Screens (Low Range)

• Impacts would be similar to Alternative F in the sequence 

of development but would result in lower impacts than the 

other alternatives.

Alternative H

Preferred Alternative - Multiple Screens

• Impacts would be similar to or less than Alternative F in 

the sequence of development, but could result in lower 

visual impacts than the other alternatives due to the use of

resource screens and mitigation and management plans for 

development.

Assumptions

Recreation uses and areas are described in Chapter 3. 

Most of the recreation resources in the study area 

consist of dispersed activities such as hunting and 

fishing. BLM stipulations would be applied. Surface 

disturbance assumptions are detailed in the Analysis 

Assumptions and Guidelines section of this chapter. 

In general, the demand for recreational activities 

would increase proportionately with the increase or 

decline of regional populations. 

Impacts from Management Common 

to All Alternatives

Recreation areas are potentially impacted by surfacedisturbing activities. The activities that involve the 

use of heavy equipment (road construction, well 

drilling, pad construction, pipeline and utility 

placement, etc.) would result in changes to the 

natural landscape, which would cause the most 

surface disturbance and have the greatest impact on 

recreation areas. Other activities, such as increased 

travel and vandalism resulting from access

improvements and increased erosion from surface 

disturbances, can also impact recreation areas. These 

activities can produce indirect impacts to recreation 

areas such as fires, hazardous waste spills and 

cleanups, changes in livestock grazing patterns and

changes in wildlife habitats. 

BLM has stipulations to protect developed recreation 

areas and undeveloped recreation areas receiving 

concentrated public use The state also has 

stipulations for protection of recreation areas 

including prohibiting activity within 100 feet of 

streams, ponds, lakes, or other water facilities. 

Additional state stipulations include a 1/8-mile buffer 

for rivers, lakes, or reservoirs and a sensitive areas 

stipulation that may be used when field staff receive 

comments regarding recreation areas. Most of the 

recreation resources in the study area are dispersed 

activities, such as hunting and fishing and are not 

developed recreation sites. Exploratory activities 

such as drilling and testing would temporarily 

displace game species locally. Installation of oil and 

gas production facilities in areas used for hunting, 

hiking and other dispersed recreational activities 

would infringe on the solitude and rural 

characteristics of the area. The oil and gas 

infrastructure and activities would reduce the number 

of game animals in the area or force some game 

animals to leave the area which would reduce or 

eliminate certain hunting activities. Hunters would be 

concerned about shooting around facilities and 

equipment.
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Exploration and production would create new roads 

that would provide easier motorized access to areas 

that may not have been accessible before. Motorized 

recreation user groups would see this as a benefit to 

their sports and would appreciate increased access to 

streams, lakes and hunting areas. Non-motorized 

recreational enthusiasts who seek solitude and quiet, 

including backpackers, hikers and some hunters and 

anglers, would not benefit from road development. 

As formerly remote areas become more accessible 

and competition for limited resource escalates, 

conflicts among these user groups would occur. 

Increased human access and increased human activity 

associated with exploration and development would 

result in increased legal and possibly illegal harvest 

of fish from nearby drainages. Increased legal harvest 

would be a recreation benefit as fishing opportunities 

are more accessible to a wider range of people and 

game regulations are adapted to accommodate the 

increased fishing pressure. However, if increased 

illegal harvest causes fish populations to drop below 

a sustainable level, fishing as a recreational resource 

could be affected. 

Increased access typically causes an increase in 

vandalism and the need for law enforcement. As 

recreation in public lands becomes more popular, 

undeveloped recreation sites would generally require 

more time and attention and have the potential to 

become developed sites, if use becomes concentrated 

to that level. Exploration and production activities 

may cause some ranches to be closed to hunting 

access via surface agreements. 

While impacts related to human access would likely 

increase in areas of CBNG development, public 

access is limited within much of the area, so that such 

impacts are expected to be small for most of the 

public. Current development has limited access by 

the use of locked gates and not granting public access 

to development areas.

Effects on recreation from the proposed Tongue 

River Railroad would vary, depending on the 

alignment constructed. The Original Preferred 

Alignment ROW would run through the Tongue 

River Reservoir State Park and the second-home 

subdivision of Cormorant Estates and affect access to 

the park and reservoir shoreline. The Western 

Alignment would be located between one and two 

miles from public camping areas at the state park, but 

the line would be constructed in cuts through most of 

this area to provide both a visual barrier and sound 

buffer from the camping areas. This alignment would 

avoid Cormorant Estates. The Four Mile Creek 

Alternative would also avoid Cormorant Estates and 

be located farther from the state park (STB 2004).

Recreational fishing opportunities are available at 

public access points along the Tongue River, 

although access for much of the river is controlled by 

private landowners. During construction, the quality 

of recreational fishing may be affected by additional 

turbidity or modified fish behavior. Access to the 

river may also be impaired in those areas where the 

railroad is between the river and the Tongue River 

Road (STB 2004). 

Impacts from Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG

Management)

Construction of roads, well pads and facility sites in 

designated recreation areas or immediately adjacent 

to them would detract from the quality of the 

recreation areas and diminish the quality of the 

recreational experience. Each well would present its 

own set of unique circumstances that would need to 

be mitigated to minimize impacts. Exploratory 

activities such as drilling and testing would 

temporarily displace game species locally. Since 

there would be no production activities in BLM 

planning areas under this alternative, there would not 

be direct impacts from production occurring on 

BLM-administered surface. 

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described above for recreation in general. If 

there were no CBNG development on tribal Lands, 

then there would be minimal impacts on recreation 

on the reservation. Impacts to hunting and fishing 

from trespassing could impact Native Americans who 

rely on these resources for subsistence purposes. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusion

Cumulative impacts would include the effects of 

Alternative A combined with conventional oil and 

gas development and other projects discussed in the 

Minerals Appendix. These would include impacts 

from nearby activities such as mining or power 

generation facilities, which can result in increased 

use due to increases in population associated with 

additional available jobs. (Note: surface mining is 
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preparing to expand by 4,000 acres under permit 

request now. See this chapter’s Introduction section.) 

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Alternative B would allow development with singlelane roads and turnouts. Upon abandonment, new 

roads would be rehabilitated and closed. Impacts 

from this alternative would be similar to Alternative 

A with the addition of increased CBNG development

resulting in increased access, resulting in increased 

impacts on dispersed recreation activities such as 

hunting and fishing. 

Crow Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting. 

Northern Cheyenne Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting.

Conclusion

The residual impact of this alternative is increased 

CBNG development, which could result in increased 

access to remote areas and increased vandalism. 

Cumulative impacts under this alternative would be 

greater than those described under Alternative A. 

Alternative C—Emphasize CBNG

Development

Impacts on recreation areas would be similar to 

Alternative B, but an increased number of disturbed 

acres and opportunities for access. Discharge of 

produced water directly to the ground could increase 

erosion. Increased erosion could lead to a reduced 

amount of land available for recreation activities and 

could disrupt habitat for game species. 

Crow Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting. The discharge of untreated 

CBNG production water on ground surfaces within 

the reservation boundary (from development adjacent 

to the reservation) could lead to localized soil 

erosion, which could result in the creation of gullies 

and limited vegetation loss that could further alter 

wildlife habitat and change hunting opportunities.

Northern Cheyenne Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting. The discharge of untreated 

CBNG production water on ground surfaces within 

the reservation boundary (from development adjacent 

to the reservation) could lead to localized soil 

erosion, which could result in the creation of gullies 

and limited vegetation loss that could further alter 

wildlife habitat and change hunting opportunities.

Conclusion

The residual impacts of this alternative are similar to 

Alternative B. The greater surface disturbance from 

roads could increase the opportunity for access to 

remote areas. The discharge of water could increase 

erosion and damage lands used for recreation.

Cumulative impacts would be greater than those 

described under Alternative B, but on a large scale 

because of the emphasis on CBNG development. 

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Impacts on recreation resources would be similar to 

Alternative B, but less because of water management 

measures to eliminate soil erosion by piping 

discharged water to the nearest body of water. 

New oil and gas roads would remain open or closed 

at the surface owner’s discretion. Open roads would 

create impacts; closed roads would prevent impacts. 
CHAPTER 4

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Crow Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting.

Northern Cheyenne Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting.

Conclusion

The residual impacts of this alternative would be 

similar to those described under Alternative B. 

Cumulative impacts would be greater than those 

described under Alternative A because of the 

expanded CBNG development. 

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Alternative E would allow CBNG development 

subject to existing planning restrictions and balances 

CBNG development and the protection of the natural 

environment. Impacts on recreation areas would 

include the loss of land for recreation purposes and

the disruption to recreation activities. Each well 

would present its own set of unique circumstances 

that would need to be mitigated to minimize impacts. 

Exploratory activities such as drilling and testing 

would temporarily displace game species locally. 

Impacts from surface disturbance would be 

minimized by using existing disturbances where 

possible. Because transportation corridors are not 

required, the number of disturbed acres and 

opportunities for access would be greater than 

Alternative B. 

Crow Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development.

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting. 

Northern Cheyenne Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife migration patterns, which could affect onreservation hunting.

Conclusion

The residual impacts of this alternative are similar to 

Alternative B. Surface disturbance from roads would 

be greater than Alternative B, increasing the 

opportunity for access to remote areas. 

Cumulative impacts would be similar to those 

described under Alternative B.

Alternative F—Phased Development 

Multiple Screens (High Range)

Impacts on recreation areas would be similar to 

Alternative E, including the loss of land for 

recreation purposes and disruption of recreation 

activities. However, surface disturbance from roads 

and utilities would be similar to or less than those 

discussed under Alternative B, because transportation 

and utility corridors may be required based on 

watershed-level planning. Corridors planned at the 

watershed-level would require actions to minimize 

resource impacts from federal CBNG development. 

During the first several years of the planning period, 

the number of disturbed acres and opportunities for 

access from federal CBNG development would be 

less than Alternative E, resulting in lower initial 

impacts to recreation. However, the number of 

disturbed acres and opportunities for access could be 

similar to Alternative E during the latter half of the 

planning period as the predicted annual limits on 

federal CBNG wells increase. 

Recreation impacts under Alternative F could be less 

than the other alternatives because each proposal for 

development would be subject to review against the 

four resource screens (air, water, wildlife and Native 

American concerns) and planning and mitigation

requirements. This review process would balance 

CBNG development with protection of the natural 

environment. Recreation is not an individual screen 

for the POD review process, but is considered in 

individual analyses. Additionally, key environmental 

and wildlife resources are subject to the screening 

process. Protection of these resources would help 

maintain some wildlife habitat. The anticipated lower 

level of development intensity in the crucial sagegrouse habitat areas is an example of how wildlife 
CHAPTER 4

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protection measures may influence impacts to 

recreation opportunities. Specifically, fewer roads 

within the sage-grouse habitat areas may reduce 

access to some lands, which may increase the quality

of some hunting opportunities. Conversely, increased 

road density could aid guides in increasing hunter 

success rates.

Crow Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife distribution patterns, which could affect onreservation hunting. 

Northern Cheyenne Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Fragmentation of wildlife habitat by surface 

disturbances outside of the reservation may change 

wildlife distribution patterns, which could affect onreservation hunting. However, there appears to be 

little or no seasonal migration of mule deer in 

southeastern Montana (BLM 1984b).

Conclusion

The residual impacts of this alternative would be

similar to Alternative E. Surface disturbance from 

federal CBNG development would be less than 

Alternative E and similar to Alternative B because 

watershed-level analysis would further limit the 

amount of surface disturbance and the disposal of 

produced water. 

The amount of cumulative impacts would eventually 

be similar to that expected under Alternative E.

Impacts may include the loss of land for recreation 

purposes, disruption of recreation activities and

increased use due to increases in population 

associated with additional available jobs. These 

impacts would result from CBNG-related activities 

under this alternative, as well as other activities 

existing or proposed within the area, such as 

conventional oil and gas development, coal mining, 

power generation plants and the Tongue River

Railroad.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Overall impact to recreation at the end of the 20-year 

development cycle would be noticeably less than that 

of the other action alternatives because Alternative G 

would result in approximately one-third the number 

of wellheads. Alternative G would be similar to 

Alternative F in the sequence of development 

predicted and impacts would accumulate each year as 

the number of developed wells increases. Since 

development would be distributed over several 

watersheds, those with the greatest number of 

wellheads could experience the greatest impacts from 

federal CBNG development. 

Crow Reservation

Impacts on the Crow Reservation would be similar in 

nature to those described for Alternative F; however, 

the amount of impacts would be less than the other 

action alternatives due to the limited number of wells 

that would be developed. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusions

Overall impacts of this alternative would be similar

in nature to Alternative F. Surface disturbance from 

federal CBNG development would be less than the 

other action alternatives due to the limited number of 

wells that would be developed. Additionally, 

watershed-level analysis could further limit the 

amount of surface disturbance and the disposal of 

produced water. Discharge of produced water directly 

to surface waters could increase erosion which could 

lead to a reduced amount of land available for 

recreation activities or disrupt habitat for game 

species. 

As with Alternative F, short-term construction 

impacts would be greater than the long-term impacts 

because the footprint of each operating well is 

smaller than the necessary construction footprint.

Cumulative impacts would be less than those 

described under the other action alternatives because 

fewer total wells would be developed. 

Alternative H—Preferred Alternative - 

Multiple Screens

Overall impacts to recreation would be similar to or 

less than Alternatives E and F. Based on a rate of 

development similar to that predicted for Alternative 

F, impacts from federal CBNG development under 

Alternative H would be lower during the first few 

years of the planning period than Alternatives B, C, 

D and E. Impacts would accumulate each year 
CHAPTER 4

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thereafter as the number of developed wells 

increases. Since development is distributed over 

several watersheds, those with the greatest number of 

developed wells could experience the greatest impact 

to recreation activities. The greatest effects due to 

federal development are predicted to be in the Lower 

and Upper Tongue, Middle Powder and Rosebud 

watersheds based on the anticipated resource 

availability and level of development these areas are 

anticipated to receive the greatest number of CBNG 

wells.. 

Recreation impacts under Alternative H could be less 

than the other alternatives because each proposal for 

development would be subject to review against the 

four resource screens (air, water, wildlife and Native 

American concerns) and planning and mitigation

requirements. This review process would balance 

CBNG development with protection of the natural 

environment. Recreation is not an individual screen 

for the POD review process, but is considered in 

individual analyses. Additionally, key environmental 

and wildlife conditions are subject to the screening 

process. Implementation of these conditions would 

help maintain wildlife habitat. 

Impacts on recreation areas may include the loss of 

land for recreation purposes and the disruption to 

recreation activities. Exploratory activities such as 

drilling and testing would temporarily displace game 

species locally. 

BLM would require a water management plan and 

use watershed-based thresholds for the volume of 

untreated water that could be discharged to surface 

waters from federal CBNG wells. These requirements 

would be in addition to the surface water quality and 

discharge volume limitations already included in the 

MPDES discharge permitting process.

Disturbance to movement of big game species due to 

new roads could be less than Alternatives E and F 

because there would be minimal road construction. 

Transportation corridors (proposed roads, flowline 

routes and utility line routes) would be located to 

follow existing routes, or areas of previous surface 

disturbance, where possible. 

Cumulative impacts to water quality and quantity 

would result within the watersheds as both federal 

and state/private development occurs. However, 

Alternative H includes watershed-level analysis as 

part of POD development and review to evaluate and 

address cumulative impacts as they are identified.

Crow Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. The 

Native American concerns screen would provide an 

additional level of resource protection for 

development proposed within 5 miles of the 

reservation and in the vicinity of traditional cultural 

properties through consultation with the tribe and 

monitoring during development.

Northern Cheyenne Reservation

Most recreation resources on the reservation will not 

be affected by off-reservation development. 

Additionally, the Native American concerns screen 

would provide an additional level of resource 

protection for development proposed within 5 miles 

of the reservation and in the vicinity of traditional 

cultural properties through consultation with the tribe 

and monitoring during development.

Conclusion

The residual impacts of this alternative are similar to 

Alternatives E and F. Development could result in 

increased access to remote areas and increased 

vandalism. Short-term construction impacts would be 

greater than the long-term impacts because the 

footprint of each operating well is smaller than the 

necessary construction footprint.

Cumulative impacts would be similar to those 

described under Alternative B and would result over 

time and within the watersheds as both federal and 

state/private CBNG well development occurs.

Cumulative impacts would include the effects of 

CBNG development combined with other existing or 

proposed activities, such as conventional oil and gas 

development, coal mining, power generation plants

and the Tongue River Railroad. These activities 

could result in increased use due to increases in 

population associated with additional available jobs.
CHAPTER 4

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Social and Economic Values

Social and Economic Values

Socio-economics address the changes in demographics; social 

organization, including housing, attitudes and lifestyles; 

economics, such as employment, unemployment, and per capita 

income; and government revenue sources, including taxes, state 

oil and gas lease income, federal mineral revenues and private 

landowner revenues.

Alternative A

No Action (Existing CBNG Management)

• Few social impacts (only small changes in employment, 

population, demand for services, etc.). 

• Small impact on economic conditions as a result of new 

production wells.

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• It is expected that most new CBNG jobs would be filled 

by CBNG workers commuting from Wyoming. If this 

occurs, social benefits and impacts could be less than 

described below.

• Social impacts would include new jobs and new 

population moving to the area.

• Economic benefits include generation of new personal and 

government income.

• Additional disposal costs associated with injection of 

produced water.

• Additional demands on public services.

Alternative C

Emphasize CBNG Development

• Social impacts same as Alternative B. Increase in impacts 

on lifestyles and values.

• Economic impacts same as Alternative B. Increase in 

impacts to water resource users.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Social impacts same as Alternative B. Small increase in 

impacts on lifestyles and values.

• Economic impacts same as Alternative B. Small increase 

in impacts to water resource users.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Social impacts same as Alternative B. Public burden to 

maintain roads may increase depending on landowner 

access decisions.

• Economic impacts same as Alternative B, except that oil 

and gas income may be less depending on water treatment 

costs.

Alternative F

Phased Development Multiple Screens (High Range)

• Because development is phased, it is likely that most new 

CBNG jobs would be filled by CBNG workers 

commuting from Wyoming. 

• Social impacts similar to Alternative E and less than 

Alternatives B through D during certain years, but longer 

in duration due to phased development.

• Economic benefits and impacts lower than Alternatives B 

through E, but longer in duration due to the evening out of 

CBNG activities over the phased development period.

• The potential for 2,333 fewer wells to be drilled in crucial 

sage-grouse habitat would have little discernible impact 

on the number of jobs or duration of the overall project.

• Reduction of wells or resource recovery in crucial sagegrouse habitat will reduce the revenues to operators, 

royalties and taxes paid to the Federal, State and local 

government, as well as potentially affecting some private 

mineral estate owners.

Alternative G 

Phased Development Multiple Screens (Low Range)

• Social impacts less than other development alternatives, 

with duration of impacts similar to Alternative F due to 

phased development. 

• Economic benefits and impacts lower than Alternatives B 

through F, with duration of impacts similar to Alternative 

F due to phased development. 

Alternative H 

Preferred Alternative - Multiple Screens

• Social and economic impacts similar to Alternative F due 

to similar rate of CBNG well development. 

Assumptions

It is assumed that the average CBNG production well 

in Montana produces about 125,000 cubic feet per day 

(MBOGC 2001a). Using a gas price of about $4.00 per

thousand cubic feet, the average well would generate 

about $182,500 per year in total income. Incomeproducing wells on average are expected to last 

between 10 and 20 years, with an average production 

life of 15 years. Exploration wells do not produce 

income. 

The social and economic analysis in this chapter is 

based on the RFD rate of development over a 20-year 

period for Alternatives A through E and up to a 23-

year period for Alternatives F, G and H. During this 

20- or 23-year period, all CBNG wells would be 

drilled and production would peak. However, because 

CBNG wells typically produce for 10 to 20 years, a 

well drilled in year 20 would continue to produce until 

year 40. Thus, social and economic consequences of 

production and abandonment would continue for up to 

20 more years beyond the period assessed here.
CHAPTER 4

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4-177

The number and type of jobs related to CBNG 

development would vary with the project phase, 

exploration, development, production, or 

abandonment. During exploration and development, 

the majority of jobs created would be for well drillers 

and pipeline installers along with specialty positions 

such as land surveyors, supervisors and geologists. A 

number of related support personnel (e.g., truck drivers 

and material handlers) would also be required during 

these activities. During production, most new jobs 

would be for maintenance and repair workers and their 

supervisors. During abandonment, field workers, 

support workers and their supervisors would be in 

demand. Average numbers and types of jobs and their

associated wages are estimated based on a recent 

report on the economic impacts of CBNG development 

in the Powder River Basin (ZurMuehlen 2001), which 

assumes the following ratios: 49 jobs per 160 wells for 

exploration/development; 9 jobs per 160 wells for 

production; and 12 jobs per 160 wells for 

abandonment.

Based on interviews with CBNG operators currently 

working in the Planning Area, it is likely that workers 

from Sheridan, Buffalo and Gillette, Wyoming would 

fill most of the new jobs related to CBNG and 

described in the alternatives (Langhus 2006). Most of 

the CBNG companies and related service companies 

have offices located in these Wyoming cities while one 

CBNG company has an office in Billings, Montana 

and service companies have offices located in Billings, 

Forsyth and Miles City.

For most of the well sites, CBNG workers would

commute on a daily basis from their homes in 

Wyoming. See Map 4-3 for a depiction of existing 

CBNG well sites, proposed development areas (based 

on existing coal deposits) and roads CBNG workers 

would use to access development areas. The first years 

of CBNG development would likely be near the 

Wyoming border and the Tongue River (Big Horn 

County), just north of Sheridan. In later years, 

development would likely move east into Powder 

River County, north of Gillette. The last wells to be 

developed would likely be those to the north in 

Rosebud County and in the counties west of the 

reservations. The number of wells to be developed in 

the western portion of the Planning Area would be

much lower than in the eastern portion. Some workers

who would be unwilling to commute would likely 

share or bring their own camping facilities. Motels 

may provide temporary housing for CBNG workers. 

Recent interviews with operators indicate they would

be able to meet the CBNG labor demand for the 

alternatives within their existing organizations. One 

reason this will be feasible is that work on each well 

during each phase of development would be short-term 

and often part-time. For example, installation of each 

well would require a crew of 7 to 8 workers over 3 to 5 

days for drilling, with an additional 2 to 3 days for 

completion work. Rather than have multiple crews 

install many wells at the same time, the same crew 

would move from site to site installing wells over a 

longer period of time. The abandonment phase would

work in a similar manner. During the operational 

phase, only a few workers would be needed to monitor 

wells since, due to automated systems, only short and 

periodic visits to the wells would be needed. A small 

number of workers would be needed for water 

management. Most water treatment technologies are 

automatically operated and assembled from modular 

components.

To simplify this analysis, all dollar amounts (e.g., 

wages and other project-related income) are reported in 

2002 dollars, as originally used in the Statewide 

Document, with no adjustment for inflation over time.

Impacts From Management Common 

to All Alternatives

Although many jobs are estimated to be created by 

CBNG development, the socioeconomic impacts of 

this development would depend to a great extent on 

how the operators distribute employment. If current 

CBNG industry employees from Wyoming fill the jobs 

created by the proposed CBNG development as 

expected, the economic benefits of the wages earned 

would mainly go to Wyoming. Some indirect benefits 

in the Planning Area would be realized due to 

expenditures near CBNG sites (gas stations, 

restaurants, stores, etc.).

There are few towns and commercial establishments 

between Sheridan or Gillette and the Montana CBNG 

sites where workers would be able to spend their 

wages or purchase supplies. For that reason, most 

indirect employment and income from support 

expenses would occur in Wyoming. Most of the 

CBNG employees working in Montana commute from 

Wyoming (BLM 2003). 

Impacts on social conditions would include changes in 

the services provided by governments due to increased 

funds from CBNG development; the effects of drilling 

and related activities on rural lifestyles in the project 

area; and changes in levels of traffic, noise, visual 

resource impacts and psychological stress levels, as 

described below. Employment and population would 
4-178 
CHAPTER 4

Social and Economic Values

4-179

not likely change because CBNG workers would be 

supplied by the existing workforce in Wyoming. This 

would limit both the employment opportunities and 

adverse effects of population change on local housing, 

schools and services.

The information reflected in the public comments and 

newspaper reports summarized in Chapter 3 indicate a 

range of attitudes and beliefs with respect to the 

development of CBNG and its relationship to the 

lifestyles and values of area residents. 

As discussed in Chapter 3, the majority of public 

comments received during scoping related to concerns 

about impacts on the environment and water quality 

and quantity in particular. The possibility of 

unfavorable economic impacts resulting from 

environmental impacts are also a concern. Other 

concerns include possible increases in traffic levels, 

noise, visual resource impacts and psychological stress 

associated with changes to the surrounding built and 

natural environment. 

Numerous social and cultural impacts have been 

predicted by Native Americans as a result of CBNG 

development on adjacent private, state and federal

minerals. These potential impacts include: the lack of 

access to energy-related employment, population 

influx, over-commitment of tribal revenue, abridged 

effectiveness of tribal governments, stressed 

infrastructure and service related capacity, altered 

social organization and social well being perception

and the further influence of western culture resulting in 

changes to traditional beliefs and value systems.

Direct economic impacts of the project would include 

lease, royalty and production payments; taxes and 

other government levies; impacts resulting from 

changes in environmental quality; and related changes 

in the fiscal health of county, state and federal 

governments. Changes in personal income resulting 

from new employment of CBNG workers and 

purchases of services from vendors are more likely to 

occur in Wyoming than the Planning Area. Similarly,

indirect impacts including induced economic activity 

from local purchases of equipment, supplies and

services and induced economic activity from purchases 

of goods and services by project workers would also be 

most likely to occur in Wyoming. The largest 

economic benefit from CBNG development is the 

methane itself, measured by the revenues obtained by 

the companies involved in developing the resource. It 

is assumed that most of these revenues would go to 

out-of-state companies. Montana’s share of that benefit 

would come mostly in the form of natural gas taxes 

and royalties, discussed below.

Conventional oil and gas development would have 

economic impacts on landowners, communities, 

county governments, reservations and the state and 

Federal governments. When hydrocarbons are 

produced and sold, the operator is responsible for 

paying the mineral owner and governmental entities in 

the form of taxes and royalties. 

Property values would be affected by full field 

development. Full-size ranches would be impacted by 

the increase in activity accompanying development. 

This could include such factors as the change in rural 

character of the land. Ranchers choosing to sell their 

ranches would receive less monetarily if the ranch sells 

without mineral rights attached. Outfitting would be 

impacted from the visual intrusion of increased road 

and CBNG facility development, causing a decline in 

outfitting income.

Conventional well development is projected at 

between 595 to 2,325 additional oil and gas wells over 

the next 20 years. This level of industrial activity 

(average 116 wells per year) would have negligible 

impact on the social and economic resources of the 

area. 

It is expected that development will occur first within 

the southern portion of the Planning Area along the 

Montana/Wyoming border and then expand to the 

north and to the east of the CX Field. CBNG workers 

that come from Sheridan, Buffalo or Gillette, 

Wyoming to work in the existing CBNG fields and the 

areas most likely to be developed next in Montana will 

not travel across the Northern Cheyenne or Crow 

reservations on their journey to work. 

When the wells to the north of the Northern Cheyenne 

Reservation are developed, CBNG workers may need 

to drive across the Northern Cheyenne Reservation to 

reach some of the sites. Although the number of wells 

predicted in the RFD to be developed north of the 

Northern Cheyenne Reservation is relatively small, 

limited traffic, noise, safety and road maintenance 

impacts on the reservation could occur. The Northern 

Cheyenne are concerned that this would increase tribal

member contact with outsiders, increasing the negative 

effects of social change described above. However, 

with any of the alternatives, there would be little 

reason for CBNG workers to stop on the reservation, 

because few services are offered on the reservation 

routes that would be used. Interaction with commuting 

workers is not expected. 

CBNG workers needing to travel from Sheridan or 

Gillette to the potential CBNG sites in the western part 

of the Planning Area would likely drive from Sheridan 

to Lovell, Wyoming or travel north from Powell, 

Wyoming or travel south from Billings, Montana. 
CHAPTER 4

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4-180

Cumulative effects of coal development in Wyoming, 

including CBNG development, is discussed in the Task 

3C Report for the Powder River Basin Coal Review 

Cumulative Social and Economic Effects Report 

(BLM 2005e). The analysis projects employment in 

the Wyoming Powder River Basin to increase by onethird (more than 2,300 jobs) compared to 2003 levels, 

with the largest growth occurring by 2010. The 

increase in employment is expected to increase income 

to individuals and government agencies in the area, but 

would also stimulate migration to the area, resulting in 

shortages in housing and community services. Effects 

to communities would depend on how well they can 

absorb the increase in population. Development of 

CBNG in Montana would increase these cumulative 

effects because CBNG operators are expecting to use 

the same workforce in Wyoming to develop CBNG 

wells in Montana. 

If the Tongue River Railroad is built, there would be 

cumulative socioeconomic effects in areas where the 

railroad is near CBNG sites. Construction of the 

railroad would create primary and secondary jobs and

promote purchases of equipment and material from 

local vendors. However, construction labor 

requirements raise the potential for creating temporary 

(2- or 3-year) demands on limited local services. The 

increased taxable revenues would benefit local 

governments and school districts. Land use effects 

from construction of the railroad would include 

permanent acquisition of land for railroad right-of-way 

and short-term acquisition of land for construction 

areas. Some parcels would be severed, which could 

interfere with cattle and wildlife movement and 

irrigated agriculture. Presence of the railroad through 

or near recreational home sites could reduce the market 

value of the individual tracts. Construction of the 

railroad would increase in vehicle travel on local roads.

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

As explained under the Assumptions section, most jobs 

created for CBNG development in Montana would 

likely be filled by Wyoming CBNG workers. This is

true for Alternative A as well. In general, the scenario 

below lists greater economic benefits and greater social 

impacts than would likely occur. 

Employment and Unemployment

The location and distribution of the exploratory wells 

by county is not known and therefore, this analysis 

assumes the wells in the two RMPs are distributed 

across those areas and the wells to be drilled statewide 

are also distributed geographically in proportion to the 

RFD estimates for development. The production wells 

are assumed to be confined to the CX Ranch in Big 

Horn County. 

Average numbers and types of jobs and their 

associated wages are estimated based on a recent 

report on the economic impacts of CBNG development 

in the Powder River Basin (ZurMuehlen 2001), which 

assumes the following ratios: 49 jobs per 160 wells for 

exploration/development; 9 jobs per 160 wells for 

production; and 12 jobs per 160 wells for 

abandonment. As shown in Table 4-58, the estimated 

number of jobs created under Alternative A would 

range between 175 (Year 1) and 14 (Years 8 

through 19), for an average of about 32 jobs per year 

over the period. This change would be small compared 

to the total employment in the Planning Area (122,000

in 1998). For Alternative A, it is assumed that all wells 

would be abandoned by year 20 of the project.

Measurable indirect changes to local employment

would not be anticipated for Alternative A. The 

purchase of equipment, supplies and services related to 

the proposed wells would have some impact but likely 

would not be distinguishable from the existing 

economic activity in the Planning Area and in the state.

Thus, few or no new jobs would be created indirectly. 

New employment created directly and indirectly for 

Alternative A would be small in relation to total 

employment in the Planning Area (122,000 in 1998)

and therefore, it would not be expected to result in 

changes to current county or state unemployment rates.

Demographics

Employees who would fill the CBNG jobs would 

likely be a mixture of current residents from the 

surrounding areas and those who would be drawn to 

the project and its employment opportunities from 

around the region. It is assumed that local labor (i.e., 

those within commuting distance of the CBNG well

locations) would be used to the extent available;

however, many of the new jobs would likely be filled 

by new migrants to the region. The degree to which the 

jobs would be filled by current residents would depend 

on a number of factors, including job skills. The extent 
4-181 

TABLE 4-58
CHAPTER 4

Social and Economic Values

4-182

to which workers who move to the region for new jobs 

would bring families with them would depend on a 

number of factors, most notably the duration of the job 

in a given location. Assuming a mixture of single 

employees and those with families, it is estimated that, 

on average, each new employee would bring one 

additional person to the region. Even if all the jobs 

(175 during Year 1) were filled by new migrants to the 

region and resulted in new persons moving to the area, 

the total new population (perhaps 350 persons) would 

be small compared to the total regional population 

(196,000 in 2000). There would likely be some 

concentration of new residents associated with jobs in 

Big Horn County related to the CX Ranch. Given that 

any new population would be spread over both time 

and geographic area, no change in demographics

would be anticipated from Alternative A.

Social Organization

Housing Units and Vacancy

Only small changes in the supply or demand of 

permanent or temporary housing are anticipated as part 

of Alternative A. This follows from the small changes 

in employment and population discussed above. 

However, there could be short term localized housing 

shortages depending on the size of the population 

increase in Big Horn County. 

Public Services and Utilities

The relatively small scale of CBNG well development 

would not result in any substantial changes in the 

ability of county, state, or Federal governments to 

provide public services or utilities. The basis for this 

conclusion is the lack of additional temporary or 

permanent population and the associated lack of 

demand for additional public services. However, there 

could be short term localized increases in public 

services demands depending on the size of the 

population increase in Big Horn County. 

Attitudes, Beliefs, Lifestyles and Values

The limited development of CBNG proposed for 

Alternative A likely would be experienced by the 

communities in the Planning Area as a continuation of 

existing oil and gas development practices in the 

region and in the state. As a result, these actions by 

themselves would likely be perceived as generally 

consistent with the attitudes, beliefs, lifestyles and

values of most population groups (e.g., ranchers, 

Native Americans, small town residents). 

Personal Income

Wages paid to project employees would contribute to 

the total personal and per capita income of every 

county where employees reside. As shown in 

Table 4-58, total direct wages from Alternative A over 

20 years are estimated at about $21 million and would 

range from a high of $5.2 million (Year 1) to a low of 

$539,000 (Years 8 through 19). 

Any of the producing wells proposed for operation on 

the CX Ranch would generate new personal income, 

depending on ownership. Individuals who own the 

mineral rights to their land and lease those rights to 

developers as part of the existing management scenario 

would receive additional income from rents or 

royalties. Although only a small percentage of 

landowners own mineral rights, the royalty income to 

any one individual would still be substantial over many 

years if a given well is highly productive. Individuals 

on whose land CBNG is developed but who do not 

own the mineral rights to their land would receive onetime payments as compensation for land disturbance. 

However, given the small scale of production 

anticipated, these changes to personal income likely 

would have only a small effect on the per capita 

income of the Planning Area or the state as a whole.

Additional personal income for residents of the 

counties and the state would be generated by 

circulation and re-circulation of dollars paid out as 

business expenditures and as state and local taxes. 

Government Revenues

The primary source of government revenues generated 

by the project would be from taxes levied on property, 

equipment, income and natural gas output generated by 

production wells. Exploratory wells would generate 

government income only to the extent the associated 

temporary facilities are subject to local property taxes. 

Oil and Gas Income

Royalties of 12.5 percent are typically earned for oil 

and gas production on state and federal lands. About 

50 percent of royalties paid to the federal government 

are generally returned to the state from which they 

originate. Assuming the 250 production wells on the 

CX Ranch proposed for Alternative A each generate 

about $182,500 in gross production income per year 

(assuming production of 125,000 cubic feet per day 

and a price of $4.00 per thousand cubic feet), the total 

annual gross income would be about $45.6 million per 

year for an average of 15 years. About 12.5 percent, or 

$5.7 million, of this new income would accrue to the 

state, federal, or private mineral owner annually. 
CHAPTER 4

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4-183

Rents on state and federal lands leased for oil and gas 

development are bid competitively, with the lowest bid 

being $1.50 per acre. Resulting government income 

would depend on the specifics of leases on the CX 

Ranch; however, it is assumed that additional income 

would accrue to the state and federal government. 

Taxes

Income Taxes

A portion of the taxable income (wages, rent or royalty 

income and land disturbance payments) generated by 

Alternative A would accrue to the state as income tax 

revenue. Income taxes would be paid on the annual 

wages paid for the average 32 jobs per year discussed 

under Employment. Dividing the estimated total wages 

over 20 years by the estimated total jobs for the same 

period (Table 4-58), the average annual salary per job 

would be about $34,000. Income in Montana is taxed 

according to a graduated rate structure with rates 

ranging from 2 percent to 11 percent of taxable 

income; the average rate in 2000 was about 3 percent 

(Montana Department of Revenue 2001). It is 

important to note that these sums are already included 

in the estimates of personal income (income taxes are a 

transfer of personal income to the state). Thus, 

estimated income tax revenues from an annual average 

of 32 jobs at $34,000 would range from $21,800 

(2 percent tax rate) to $119,700 (11 percent tax rate), 

with a likely amount closer to $32,600 (3 percent tax 

rate) based on recent history. The project would result 

in an increase in state tax revenues to the extent that 

new income is created that didn’t previously exist in 

the state.

Property Taxes

Both real and personal property are subject to property 

taxes. Personal property would consist of structures, 

equipment and materials used for the proposed 

exploration and production of CBNG. Taxes on real 

property would be based on changes in the assessed 

value that result from improvements to the property. 

Each county in which facilities were located would 

assess tax levies and apply them to the taxable value of 

the relevant facilities. The levy would be based on the 

total value of property multiplied by a tax rate or rates 

specific to the property location (i.e., county and 

special service districts). Any such additional property 

taxes would contribute new income directly to both the 

county tax base and the local economy. It should be 

noted that property taxes on business equipment (e.g., 

drilling equipment) would likely be phased out by 

2006, reducing the total taxes that would be collected.

Given the limited nature of CBNG exploration and 

development proposed in Alternative A, changes in 

taxes are not expected to be substantial for any given 

county. The exception is Big Horn County, where the 

new production wells are proposed. Additional county 

tax revenues would be anticipated. Property tax 

revenues would be a cost to CBNG development 

companies and landowners and a benefit to the 

counties and the state.

Natural Resources Taxes

The products of natural resource extraction in 

Montana, including natural gas, are subject to state 

natural resource taxes, including local government 

severance taxes. Any new production of natural gas 

generated by the 250 production wells in Big Horn 

County would be subject to such taxes. Severance 

taxes are distributed to a variety of state and local 

funds and would contribute positively to the state and 

local economies.

Other Taxes

In general, the local and state economies would benefit 

from sales of goods and services by local businesses to 

oil and gas operators associated with the project. 

However, local sales of goods and services associated 

with CBNG development would not generate increases 

in tax revenues because there is no sales tax in 

Montana.

Water Resource Values

The purpose of a discussion of water resource values in 

the Economics section of this report is to acknowledge 

that the existing surface and groundwater resources in 

the Planning Area have an economic value that is part 

of the overall economy of the area and that alterations 

to these resources, would have economic impacts to 

water users or to the regional economy. Affected users 

would include those who depend on surface water or 

groundwater for irrigation, ranching, municipal water 

needs, home water needs, landscape needs and any 

other business and household need of water from a 

surface water body or well. 

Given the relatively limited scale of CBNG 

development proposed for Alternative A, effects on 

water resources and water resources economics would 

be relatively limited (see the analysis in the 

Hydrological Resources section). For Alternative A,

untreated water from exploration would be placed in 

holding facilities for beneficial re-use, which would 

provide an economic benefit to affected water users. 

No discharge to waters of the United States would be 

allowed for BLM-authorized exploration wells; the 

state has permitted discharge for the CX Ranch field of 
CHAPTER 4

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3,300 to 4,200 gpm of untreated and treated production 

water. Because of the small scale, no economic 

impacts to downstream surface water users would be 

anticipated.

Localized groundwater depletion would result over 

time (more than 5 years) from the CBNG wells 

proposed for Alternative A. However, state law (MCA 

82-11-175) requires CBNG operators to offer a 

reasonable mitigation agreement to each person who 

holds an appropriation right or a permit to appropriate 

groundwater and for which the point of diversion is 

within one mile of a CBNG well; or one-half mile of a 

well that is adversely affected by CBNG well. These 

mitigation agreements must address the reduction or 

loss of water resources and must provide for prompt 

supplementation or replacement of water from any 

natural spring or water well adversely affected by the 

coal bed natural gas well.

Crow Reservation

Impacts to social and economic values on the Crow 

Reservation would be small because it is assumed that 

no CBNG wells would be developed on the 

Reservation initially. Social impacts would be more 

likely to affect those individuals living off the 

reservations or whose activities are conducted off the 

reservations. Native American development is 

considered as part of the cumulative effects potential. 

Few, if any, tax revenues would accrue to tribal

governments as a result of off-reservation CBNG 

development. It is likely that a smaller number of 

Native Americans who are interested in the 

development of energy resources for the long-term 

social and economic betterment of tribal members 

would perceive or experience fewer impacts from 

CBNG development.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be small because it is assumed that no CBNG wells 

would be developed on the Reservation. Social impacts 

would be more likely to affect those individuals living 

off the reservations or whose activities are conducted 

off the reservations. Native American development is 

considered as part of the cumulative effects potential. 

Few, if any, tax revenues would accrue to tribal

governments as a result of off-reservation CBNG 

development. It is likely that a smaller number of

Native Americans who are interested in the 

development of energy resources for the long-term 

social and economic betterment of tribal members 

would perceive or experience fewer impacts from 

CBNG development.

Conclusions

The Alternative A management scenario is a 

continuation of existing oil and gas industry practices 

in the Planning Area and would not result in social 

impacts. They would be only a small effect on 

economic conditions in the Planning Area, as well as 

environmental and social conditions. However, there 

could be short term localized impacts to housing and 

services in Big Horn County. 

The new jobs and related social and economic impacts 

from Alternative A would be small, with the exception 

of the proposed production wells in Big Horn County, 

which would result in positive economic impacts in 

that county. Future development in the area, such as 

further expansion of existing surface coal mines, 

would likely have larger social and economic impacts 

(e.g., creation of more jobs and income) than those 

impacts from Alternative A. 

Alternative B—Emphasize Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

As explained under the Assumptions section, most jobs 

created for CBNG development in Montana would 

likely be filled by Wyoming CBNG workers. In 

general, the scenario below lists greater economic 

benefits and greater social impacts than would likely 

occur. 

Employment and Unemployment

Estimated direct employment from CBNG under the 

development scenario for the 20-year project life is 

presented in Table 4-59. (Wage information is 

discussed under Economics.) The number and type of 

jobs involved would vary with the project phase. The 

types of jobs would be the same as those described for 

Alternative A. 

As shown in Table 4-59, development (drilling of 

about 18,300 wells over 20 years) would result in an 

estimated average of 851 jobs per year, with a range 

from 334 (Year 1) to 943 (Year 18) for all project 

phases combined. The actual number of jobs in a given 

year would depend on the actual number of wells 

drilled, in production, or abandoned in that year. 

Abandonment of wells during years 21-40 would result 

in an estimated 1,054 additional jobs, for an average of 

about 53 jobs per year during that period. 
4-185

TABLE 4-59

this table.
CHAPTER 4

Social and Economic Values

4-186

The additional jobs created would be small compared 

to the total employment in the Planning Area (122,000

in 1998). However, given that most of the CBNG wells 

would be located in three counties (Big Horn, Powder 

River and Rosebud), a large number of the jobs would 

be concentrated in those counties. Because some of 

these jobs would go to non-local residents, the actual 

number of new jobs in the study area would be less.

The water management conditions included in 

Alternative B would require injection wells, the 

installation and operation of which would be 

associated with additional jobs. Water injection wells 

would be required at a rate of about 1 per 10 CBNG 

wells. This would result in an increase in jobs and 

wages of about 10 percent over those reported in 

Table 4-59 for all phases of the project combined.

In addition to the direct jobs created by the project, 

some additional jobs would be created indirectly 

through additional work for persons in related support 

industries such as truckers, material suppliers, 

inspectors and various other specialists. One estimate 

is that one indirect job would be created for every four 

direct jobs created (ZurMuehlen 2001).

The effect of the new jobs on current unemployment

rates in the area would be moderate. Although the new 

direct jobs would help boost total employment in the 

Planning Area, the increases would be limited to those 

sectors and individuals with the appropriate skills for 

the jobs and to those geographic locations where the 

jobs are located. For example, the relatively high 

unemployment rates (about 9 percent) in the mining 

sector in Big Horn and Rosebud counties would be 

decreased if unemployed persons gain employment 

from the new CBNG development.

Any new jobs filled by new residents (see the 

Demographics section) would increase the number of 

employed persons in a given county but would not 

decrease the number of unemployed persons. To the 

extent that indirect jobs are created by the project, 

some increased employment in other service industries 

also would occur.

Demographics

As with Alternative A, employees who would fill the 

CBNG jobs would likely be a mixture of current 

residents from the surrounding areas and those who 

would be drawn to the project and its employment

opportunities from around the region. It is assumed 

that local labor would be used to the extent it is 

available; however, for Alternative B it is likely that 

many additional workers (e.g., drill rig crews) from 

outside the area would be needed, especially during the 

peak employment years of the project. It is assumed 

that drill rigs from a variety of locations-both Montana 

and Wyoming-would be used, depending on supply 

and demand at any given time. The potential for new 

population is greatest in the counties where the number 

of CBNG wells to be drilled is greatest: Big Horn, 

Powder River and Rosebud counties (about 90 percent 

of proposed CBNG wells would be drilled in these 

three counties; see Table 4-60). As with Alternative A, 

it is estimated that, on average, each new employee 

would bring one additional person to the region. 

Assuming, for example, that all of the jobs were filled 

by new migrants to the area, as many as 1,986 people 

(993 x 2) might be added to the region during the peak 

employment year (Year 5). An increase of this 

magnitude would be small compared to the total 

regional population (196,000 in 2000). However, the 

new population could be concentrated in the three 

counties with the most CBNG wells (see Table 4-60). 

Because these three counties have a relatively small 

combined population (about 24,000), population 

change within these counties could be substantial. Of 

the approximately 24,000 persons in the three counties, 

about 10,400 or 44 percent are Native American (see 

Chapter 3). 

Social Organization

Housing Units and Vacancy

Depending on the type and duration of the jobs (e.g., 

long-term production supervisor versus drill rig crew 

member), new employees in the area would seek either 

temporary housing (hotels, apartments, trailer parking) 

or permanent housing (homes to purchase or to rent 

long-term). Individual choices about where to live are 

hard to predict and vary with personal preference, in 

addition to the supply of housing and availability of 

services in a given location and the mobility demands 

of a given job. The relatively limited supply of 

temporary and permanent housing in the smaller 

communities in the Planning Area would limit the 

number of new employees (and families, if applicable) 

who would be able to live there without additional 

housing and related services. The larger communities, 

such as Billings or Gillette and Sheridan, Wyoming, 

have a greater supply of temporary and permanent 

housing and would be likely settlement locations for 

people employed by the CBNG industry. In part 

because of the general trend of migration within 

Montana from the east to the west during recent years, 

vacant housing is available in a number of 

communities. As discussed in Chapter 3, vacancy rates 

for both temporary and permanent housing are 

adequate to high in the Planning Area. This 

information, combined with the large size of the 

geographic area and the dispersed nature of the new 
CHAPTER 4

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4-187

TABLE 4-60

TOTAL PROJECTED WELLS AND PERCENT BY COUNTY

Alternatives B, C, D and E Alternatives F and G

County

Wells to be 

Drilled

Percent of Total Wells to be 

Drilled1

Percent of 

Total

Big Horn 7,000 38.3% 7,000 38.4%

Blaine 10 0.1% 0 0.0%

Carbon 400 2.2% 400 2.2%

Carter 0 0.0% 0 0.0%

Custer 300 1.6% 300 1.6%

Gallatin 15 0.1% 0 0.0%

Golden Valley 0 0.0% 0 0.0%

Musselshell 150 0.8% 150 0.8%

Park 25 0.1% 0 0.0%

Powder River 6,700 36.6% 6,700 36.7%

Rosebud 2,800 15.3% 2,800 15.3%

Stillwater 700 3.8% 700 3.8%

Sweetgrass 25 0.1% 0 0.0% 

Treasure 25 0.1% 25 0.1%

Wheatland 0 0.0% 0 0.0%

Yellowstone 150 0.8% 150 0.8%

Subtotal 18,300 100.0% 18,225 100.0%

Combined Total: 16,500 90.2% 16,500 90.4%

Big Horn, Powder River, and Rosebud counties 

1

The number of wells to be drilled under Alternative G is approximately 65 percent less than Alternative F. However, 

the percent of total is the same for both alternatives.

job opportunities and associated new population, 

suggest that adequate housing opportunities would be 

available in the larger communities but might not be 

available in some of the smaller communities. 

Public Services and Utilities

Impacts on the ability of local governments to provide 

public services and utilities would be related to the 

ability of the service providers to adapt to relevant 

fiscal or physical changes from CBNG development. 

Affected services typically include police and fire 

protection, emergency medical services, schools, 

public housing, park and recreation facilities, water 

supply, sewage and solid waste disposal, libraries, 

roads and other transportation infrastructure. Given the 

large geographic scale of the CBNG development 

scenario, it is infeasible to quantitatively assess the 

relationship of the project to these individual services. 

Effects would be greatest in the three counties (Big 

Horn, Powder River and Rosebud) where most of the 

CBNG wells are proposed to be drilled; however, these

counties would also receive the greatest amounts of 

property tax and other government revenues (see the 

Economics section) that would fund improvements or 

other changes to services.

The alternatives being considered include varying 

management objectives with respect to the 

construction of roads and utilities. The construction 

and maintenance of utilities would be funded by the 

users. The decision as to whether to maintain roads 
CHAPTER 4

Social and Economic Values

4-188

upon abandonment of CBNG facilities would be up to 

the land owner, which could be either a public or 

private entity. To the extent local governments opt to 

maintain these roads after this time, additional revenue 

would be required to balance the additional costs 

required to do so.

Attitudes, Beliefs, Lifestyles and Values

The large scale development of a large number of 

CBNG wells in the Planning Area would likely 

conflict with the attitudes, beliefs, lifestyles and values 

of many individuals and population subgroups in the 

area (e.g., farmers, ranchers, small town residents, 

Native Americans, retirees, etc.). Drilling, testing and

operation of CBNG wells would result in increased 

traffic from trucks and other vehicles; noise from 

traffic and the operation of generators and drilling and 

other equipment; visual resource impacts from the 

construction of the wells themselves as well as power 

lines and related electrical infrastructure; and 

psychological stress associated with unwanted change, 

division in the community, or other impacts. The 

population subgroups would be affected to the degree 

to which their lifestyles and values are inconsistent 

with such impacts.

The majority of individuals in the Planning Area are 

understood to have traditional rural lifestyles in which 

the relatively quiet and pristine surroundings are an 

important value. They would likely find CBNG 

development inconsistent with the desired balance 

between environmental stewardship and economic 

development expressed in many of the scoping 

comments and newspaper reports. This would be 

particularly true for Big Horn, Powder River and

Rosebud counties where the majority of the wells 

would be developed. Large-scale CBNG development 

could be viewed as part of a gradual transition away 

from traditional rural and agricultural lifestyles. A 

smaller group of people in the area who are more 

interested in the potential economic benefits of CBNG 

development would likely perceive or experience 

fewer impacts with respect to lifestyles and values.

Large-scale CBNG development is likely to conflict to 

some degree with traditional Native American values 

which emphasize preservation of cultural heritage and 

a reverence for the natural environment. Native 

American groups could be affected by increases in 

noise, impacts on visual resources and plant 

populations, etc., in particular as they affect locations 

and resources used for spiritual or religious purposes. 

It is assumed that no CBNG wells would be developed 

on the Native American reservations initially and

therefore impacts would be more likely to affect those 

individuals living off the reservations or whose 

activities are conducted off the reservations. Native 

American development is considered as part of the 

cumulative effects impact potential. It is likely that a 

smaller number of Native Americans who are 

interested in the development of energy resources for 

the long-term social and economic betterment of tribal 

members would perceive or experience fewer harmful 

impacts from CBNG development.

Impacts on recreation areas would include the loss of 

land for recreation purposes and the disruption to 

recreation activities. Each well would present its own 

set of unique circumstances that would need to be 

mitigated to minimize impacts. Exploratory activities 

such as drilling and testing would temporarily displace 

game species locally. 

The subsurface discharge of produced water would 

likely be seen as consistent or somewhat inconsistent 

with the desired balance between environmental 

stewardship and economic development expressed in 

many of the scoping comments and newspaper reports. 

Impacts on groundwater would be the same for 

Alternatives B, C, D, E, F and H with the primary 

impact being the drawdown of groundwater. 

Personal Income

Wages paid to CBNG workers would contribute to the 

total personal income in the county where the 

employees reside. As shown in Table 4-59, wages

would be generated from all three project phases. Over 

the first 20 years of the project, total wages paid for all 

phases of the project would be an estimated 

$598 million. Estimated annual wages would range 

from $10 million in Year 1 to almost $35 million in 

Years 18 and 19. Although this much estimated 

personal income would be generated by the project, it 

would not all be experienced as “new” income within a 

given county or the state. New income would be the 

difference between the income of workers before 

CBNG development and the income after CBNG 

development.

A number of the producing wells in the development 

scenario would generate new personal income for 

those who own the land or the mineral rights, as stated 

under Alternative A. The circulation and re-circulation 

of direct income (including royalties to private owners) 

generated by the project would generate additional 

(indirect) personal income throughout the region. 

Government Revenues

Oil and Gas Income

Assuming each of the approximately 16,500 

production wells anticipated for Alternative B generate 
CHAPTER 4

Social and Economic Values

4-189

about $182,500 in gross production income per year of 

operation, the total annual gross income would vary 

depending on the number of wells in production in a 

given year. As shown in Table 4-59, the estimated 

number of producing wells ranges from 510 in Year 1 

to 14,100 in Year 19. It follows that the estimated 

annual gross income would range from $93 million 

(Year 1) to $2.5 billion (Year 19). Most of this revenue 

would go to methane companies and would accrue to 

the companies in the states where they are located. The 

12.5 percent royalty collected on this annual income 

would range from about $12 million (Year 1) to $322 

million per year. It is estimated that about one-half the 

well sites would be permitted on minerals administered 

by the federal government (BLM), about 5 to 

10 percent on state (private) minerals and the 

remaining 40 to 50 percent on private minerals. As a 

result, about half of the royalty income would initially 

go to the federal government, with about half of the 

federal half being returned to the state. Thus, an 

estimated 30 to 35 percent of royalty income, between 

$4 million and $113 million in a given year, ultimately 

would accrue to the state. Given that total state 

revenues received from minerals management on state 

lands in FY 2000 was $11.6 million and total federal 

mineral revenues collected on Montana lands and 

disbursed to the state were $20.4 million in FY 2000 

(see Chapter 3), new state revenues from CBNG would 

be substantial, especially during the peak years of the 

project.

Rents on state and federal lands leased for oil and gas 

development are bid competitively, with the lowest bid 

being $1.50 per acre. Resulting government income 

would depend on the specifics of the leases. It is 

assumed that additional income would accrue to the 

state and federal government from these rents.

Net government revenues would be reduced by costs 

incurred for monitoring and regulating CBNG activity.

These costs would be relatively small compared to the 

revenues generated. 

Water treatment costs for Alternative B would be 

greater than for Alternatives D, E and F and much 

greater than for Alternative C.

Taxes

Income Taxes

A portion of the taxable income (wages, rent or royalty 

income and land disturbance payments) generated by 

Alternative B would accrue to the state as income tax 

revenue. Income taxes would be paid on the annual 

wages paid for the average 851 jobs per year discussed 

above under Employment. Dividing the estimated total 

wages over 20 years by the estimated total jobs for the 

same period (Table 4-59), the average annual salary 

per job would be about $35,000 (does not account for 

inflation over time). Income in Montana is taxed 

according to a graduated rate structure with rates 

ranging from 2 percent to 11 percent of taxable 

income; the average rate in 2000 was about 3 percent 

(Montana Department of Revenue 2001). It is 

important to note that these sums are already included 

in the estimates of personal income (income taxes are a 

transfer of personal income to the state). Thus, 

estimated income tax revenues from an annual average

of 851 jobs at $35,000 would range from $596,000 

(2 percent tax rate) to $3.3 million (11 percent tax 

rate), with a likely amount closer to 894,000 (3 percent 

tax rate) based on recent history. As discussed above, 

the project would generate new income tax revenue for 

the state to the extent that revenue generated by new 

jobs, for example, exceeds existing tax revenues. The 

income tax sums are already included in the estimates 

of personal income.

Property Taxes

See general discussion of property taxes for 

Alternative A. Only at the time when a given property 

is improved (i.e., a CBNG well or other facilities are 

developed there) would estimated new property tax 

revenues be calculated. However, property taxes would 

accrue to counties roughly in proportion to the number 

of new wells. Big Horn, Powder River and Rosebud 

counties would have the vast majority of new wells; 

therefore, they would be anticipated to experience the 

greatest increases in assessed values and the greatest

increase in new county property tax revenues. These 

new revenues could help improve schools, roads, 

community services and other county assets, after any 

new costs associated with CBNG are accounted for.

Natural Resources Taxes

Natural resources taxes would be greater than 

described under Alternative A because they would be 

based on 18,000 wells.

Other Taxes

Other taxes would be the same as described under 

Alternative A.

Water Resource Values

Surface discharge of produced water would be 

prohibited and therefore surface water impacts such as 

erosion and water quality would be avoided. In the 

absence of surface water impacts, no associated 

economic impacts to surface water users would occur. 
CHAPTER 4

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4-190

The primary impact to groundwater resources is 

removal of groundwater in the Powder River Basin 

affecting wells and springs. 

Crow Reservation

Social and economic impacts from off-Reservation 

development in Alternative B would include creation 

of a limited number of new jobs in the Planning Area

and related demographic shifts from people moving to 

the area. It is anticipated the impact of added 

employment and population on social conditions on the 

Crow Reservation would be small. Some new personal 

and government income would be generated as 

discussed above. The effect of this new income on the 

Reservation would depend on a number of factors, 

including the extent to which Reservation members 

participate in the off-Reservation jobs or mineral 

ownership. Some additional demands on public 

services also would result.

See the Attitudes, Beliefs, Lifestyles and Values section 

under this alternative for additional information on 

effects to Native Americans.

As shown in the RFFA, 4,000 wells could be 

developed on the Crow Reservation. If this entire 

number of wells were developed, additional economic 

impacts would occur. Such impacts would generally be 

in the form of new jobs and employment opportunities, 

a drawdown in groundwater and additional personal 

income and revenues from CBNG development and 

production.

Indian allottees and the Crow Tribe would receive 

access, damage payments, royalties and possible tax 

revenues.

Northern Cheyenne Reservation

Social and economic impacts from off-Reservation 

development in Alternative B would include creation 

of a limited number of new jobs in the Planning Area

and related demographic shifts from people moving to 

the area. It is anticipated the impact of added 

employment and population on social conditions on the 

Northern Cheyenne Reservation would be small. Some 

new personal and government income would be 

generated as discussed above. The effect of this new 

income on the Reservation would depend on a number 

of factors, including the extent to which Reservation 

members participate in the off-Reservation jobs or 

mineral ownership. Some additional demands on 

public services also would result.

See the Attitudes, Beliefs, Lifestyles and Values section 

under this alternative for additional information on 

effects to Native Americans.

As shown in the RFFA, 4,000 wells could be 

developed on the Northern Cheyenne Reservation. If 

this entire number of wells were developed, additional 

economic impacts would occur. Such impacts would 

generally be in the form of new jobs and employment

opportunities, a drawdown in groundwater and

additional personal income and revenues from CBNG 

development and production. 

Indian allottees and the Northern Cheyenne Tribe

would receive access, damage payments, royalties and

possible taxes revenues.

Conclusion

The primary social impacts identified from 

Alternative B would be the new jobs created in the 

Planning Area as a result of development and change 

from a predominantly rural and agricultural based 

lifestyle. These new jobs would result in some 

demographic shifts as a result of people moving to the 

area. It is anticipated the impact of added employment

and population on social conditions would be small 

overall but that impacts in the three counties with the 

most CBNG activity could be greater. Alternative B 

would result in the generation of new personal and 

government income. New personal income would 

include the wages from both direct and indirect jobs 

created by the project, as well as income from land 

disturbance payments and mineral leases. Similarly, 

new local, state and federal government income would 

be generated through the variety of means discussed. 

Over the long term, there is the possibility of a “boom 

and bust” cycle as CBNG activity rises and falls.

As shown in the RFD scenario presented in the 

Minerals Appendix, in addition to the 18,300 CBNG 

wells considered for Alternative B, an additional 

8,200 CBNG wells would be developed in this area in 

the future: 4,000 on the Northern Cheyenne 

Reservation, 4,000 on the Crow Reservation and about 

200 wells on USFS land. This number is about 44 

percent of those proposed for Alternative B. If this 

entire number of wells was developed over the same 

20-year period as the other 18,300 wells, additional 

economic impacts would occur. Such impacts would 

generally be in the form of new jobs and employment

opportunities, additional population, additional 

demands on public services, a drawdown in 

groundwater and additional personal income and 

government revenues from CBNG development and 

production. Potentially large social and economic 

impacts also would result from other developments 

proposed for the area, including expansion of existing 

surface coal mines. The impacts from these other 

developments would be additive to those identified 

above for Alternative B.
CHAPTER 4

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4-191

Alternative C—Emphasize CBNG

Development

Employment And Unemployment

Employment and unemployment would be the same as 

described under Alternative B, except that there would 

be no additional jobs created from installation of 

injection wells, which would not be required for this 

alternative.

Demographics

Demographics would be the same as described under 

Alternative B. 

Social Organization

Housing Units and Vacancy

Housing units and vacancy would be the same as 

described under Alternative B.

Public Services and Utilities

Public services and utilities would be the same as 

described under Alternative B.

Attitudes, Beliefs, Lifestyles and Values

General impacts on population subgroups are the same 

as for Alternative B.

Impacts on recreation areas would include the loss of 

land for recreation purposes and the disruption to 

recreation activities. Each well would present its own 

set of unique circumstances that would be mitigated to 

minimize impacts. Exploratory activities such as 

drilling and testing would temporarily displace game 

species locally. 

Alternative C would allow discharge of untreated 

water to the land surface. As indicated in the 

Hydrological Resources section, this discharge would 

result in erosion and water quality impacts. Such 

impacts would be inconsistent with the desired balance 

between environmental stewardship and economic 

development expressed in many of the scoping 

comments and newspaper reports. The primary reasons 

for this conclusion include the potentially large scale 

of this discharge, the potential for degraded water to 

negatively affect farming and ranching operations 

(e.g., reduce economic viability), increased noise, loss 

of natural scenery and the inconsistency of this 

approach with the rural lifestyles and values discussed 

in Chapter 3.

Personal Income

Personal income would be the same as described under 

Alternative B, with the possible exception of decreases 

in farming or ranching income as a result of water 

quality and erosion impacts. See the Attitudes, Beliefs, 

Lifestyles and Values section under this alternative for 

additional information on social effects to lifestyles 

and Values.

Government Revenues

Government revenues would be the same as described 

under Alternative B.

Oil and Gas Income

Oil and gas income would be about the same as 

described under Alternative B. Water treatment costs 

would be less than for Alternative B due to the 

allowance of discharge to the land surface (see Water 

Resource Values below).

Taxes

Income Taxes

Income taxes would be the same as described under 

Alternative B.

Property Taxes

Property taxes would be the same as described under 

Alternative B.

Natural Resources Taxes

Natural resources taxes would be the same as 

described under Alternative B.

Other Taxes

Other taxes would be the same as described under 

Alternative B.

Water Resource Values

See the discussions for Alternative B. Alternative C 

would allow discharge of untreated water to the land 

surface. As indicated in the Hydrological Resources

section elsewhere in this document, this discharge 

would result in erosion and water quality impacts. In 

turn, some downstream surface water users who 

depend on surface water resources for their livelihood 

would be affected (for example, if suitable irrigation 

water were no longer available or if ranch land were 

lost to erosion). See further discussion under Attitudes, 

Beliefs, Lifestyles and Values, above. Groundwater 

impacts would be similar to Alternative B. A
CHAPTER 4

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4-192

difference is that no groundwater would be reinjected 

as it would for Alternative B, possibly increasing the 

risk of groundwater drawdown in some locations.

Crow Reservation

Impacts from Alternative C would include creation of 

a limited number of new jobs in the Planning Area and 

related demographic shifts from people moving to the 

area. The impact of added employment and population 

on social conditions on the Crow Reservation would be 

small. Some new personal and government income 

would be generated as discussed above. The effect of 

this new income on the Crow Reservation would 

depend on a number of factors, including the extent to 

which Reservation members participate in the offReservation jobs or mineral ownership. Additional 

demands on public services also would result. 

Somewhat greater impacts on water resource users and 

on lifestyles and values would occur compared to 

Alternative B. See the Attitudes, Beliefs, Lifestyles and 

Values section under this alternative for additional 

information on social effects to Native Americans.

Northern Cheyenne Reservation

Social and economic impacts from development in 

Alternative C would include creation of a limited 

number of new jobs in the Planning Area and related 

demographic shifts from people moving to the area. 

The impact of added employment and population on 

social conditions on the Northern Cheyenne 

Reservation would be small. Some new personal and 

government income would be generated as discussed 

above. The effect of this new income on the Northern 

Cheyenne Reservation would depend on a number of 

factors, including the extent to which Reservation 

members participate in the off-Reservation jobs or 

mineral ownership. Additional demands on public 

services also would result. Somewhat greater impacts 

on water resource users and on lifestyles and values 

would occur compared to Alternative B. See the 

Attitudes, Beliefs, Lifestyles and Values section under 

this alternative for additional information on social 

effects to Native Americans.

Conclusions

Residual impacts would be similar to those for 

Alternative B, except for impacts to lifestyles and 

water resource values, which would be greater for 

Alternative C than for Alternative B.

Cumulative impacts would be greater than for 

Alternative B, given the water resource impacts.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Employment and Unemployment

Employment and unemployment would be the same as 

described for Alternative B.

Demographics

Demographics would be the same as described under 

Alternative B.

Social Organization

Housing Units and Vacancy

Housing units and vacancy would be the same as 

described under Alternative B.

Public Services and Utilities

Public services and utilities would be the same as 

described under Alternative B.

Attitudes, Beliefs, Lifestyles and Values

General impacts on population subgroups are the same 

as for Alternative B.

Impacts on recreation areas would include the loss of 

land for recreation purposes and the disruption to 

recreation activities. Each well would present its own 

set of unique circumstances that would be mitigated to 

minimize impacts. Exploratory activities such as 

drilling and testing would temporarily displace game 

species locally. 

Treatment of most produced water and discharge via 

pipeline or other constructed water courses would 

eliminate most of the erosion and water quality 

impacts. 

Personal Income

Personal income would be the same as described under 

Alternative B, with the possible exception of decreases 

in farming area ranching income as a result of water 

quality and erosion impacts. See the Attitudes, Beliefs, 

Lifestyles and Values section under this alternative for 

additional information on social effects to lifestyles 

and Values.

Government Revenues

Government revenues would be the same as described 

under Alternative B.
CHAPTER 4

Social and Economic Values

4-193

Oil and Gas Income

Oil and gas income would be the same as described 

under Alternative B. Water treatment costs would be 

greater than for Alternative C and much less than for 

Alternative B.

Taxes

Income Taxes

Income taxes would be the same as described under 

Alternative B.

Property Taxes

Property taxes would be the same as described under 

Alternative B.

Natural Resources Taxes

Natural resources taxes would be the same as 

described under Alternative B.

Other Taxes

Other taxes would be the same as described under 

Alternative B.

Water Resource Values

See discussion for Alternatives B and C. Most 

discharge would be treated and carried over land in 

pipes. Surface water impacts and the potential for 

resulting economic impacts to surface water users 

would be less than for Alternative C and greater than 

for Alternative B. Groundwater impacts would be the 

same as Alternative C.

Crow Reservation

Impacts from Alternative D would include creation of 

a limited number of new jobs in the Planning Area and 

related demographic shifts from people moving to the 

area. It is anticipated the impact of added employment

and population on social conditions on the Crow 

Reservation would be small. Some new personal and 

government income would be generated as discussed 

above. The effect of this new income on the Crow 

Reservation would depend on a number of factors, 

including the extent to which Reservation members 

participate in the off-Reservation jobs or mineral 

ownership. Additional demands on public services also 

would result. Additional impacts on water resource 

users and on lifestyles and values would occur but they 

would be less than for Alternative C. See the Attitudes, 

Beliefs, Lifestyles and Values section under this 

alternative for additional information on social effects 

to Native Americans.

Northern Cheyenne Reservation

Social and economic impacts from Alternative D 

would include creation of a limited number of new 

jobs in the Planning Area and related demographic 

shifts from people moving to the area. It is anticipated 

the impact of added employment and population on 

social conditions on the Northern Cheyenne 

Reservation would be small. Some new personal and 

government income would be generated as discussed 

above. The effect of this new income on the 

Reservation would depend on a number of factors, 

including the extent to which Reservation members 

participate in the off-Reservation jobs or mineral 

ownership. Additional demands on public services also 

would result. Additional impacts on water resource 

users and on lifestyles and values would occur but they 

would be less than for Alternative C. See the Attitudes, 

Beliefs, Lifestyles and Values section under this 

alternative for additional information on social effects 

to Native Americans.

Conclusions

Residual impacts would be similar to those for 

Alternative B, except with respect to impacts on water 

resource economics and related lifestyle impacts, 

which would be less than Alternative C but greater 

than Alternative B.

Cumulative impacts would be less than Alternative C 

and somewhat greater than Alternative B, given the 

differences in water resource impacts.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Employment and Unemployment

Employment and unemployment would be the same as 

described under Alternative B. It is assumed that the 

approximate number of additional jobs created from 

installation of injection wells required for 

Alternative B would also occur for Alternative E, 

except that some of the jobs would be associated with 

the variety of site-specific produced water 

management options.

Demographics

Demographics would be the same as described under 

Alternative B.
CHAPTER 4

Social and Economic Values

4-194

Social Organization

Housing Units and Vacancy

Housing units and vacancy would be the same as 

described under Alternative B.

Public Services and Utilities

Public services and utilities would be the same as 

described under Alternative B, except that the oil and 

gas roads would remain open or be closed at the 

surface owner’s discretion, potentially increasing or 

decreasing the burden on public jurisdictions to 

maintain these roads.

Attitudes, Beliefs, Lifestyles and Values

General impacts on population subgroups would be the 

same as for Alternative B.

Alternative E would have impacts on water resources 

and water resource values that are similar to the 

impacts of Alternative B and Alternative D (see

Hydrological Resources section).

Personal Income

Personal income would be the same as described under 

Alternative B.

Government Revenues

Government revenues would be the same as described 

under Alternative B.

Oil and Gas Income

Oil and gas income would be about the same as 

described for Alternative B, although water treatment 

costs could be greater, thus potentially decreasing the 

net income to producers.

Taxes

Income Taxes

Income taxes would the same as described under 

Alternative B.

Property Taxes

Property taxes would be the same as described under 

Alternative B.

Natural Resource Taxes

Natural resource taxes would be the same as described 

under Alternative B.

Other Taxes

Other taxes would be the same as described under 

Alternative B.

Water Resource Values

Alternative E would have impacts on water resources 

and water resource values that are similar to the 

impacts of Alternative B and Alternative D (see 

discussion in Hydrological Resources section). The 

activities proposed to prevent the degradation of 

surface and groundwater resources would substantially 

reduce erosion and surface water quality impacts. 

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described above for Alternative E. Social and 

economic impacts would include creation of a limited 

number of new jobs in the Planning Area and related 

demographic shifts from people moving to the area. 

The impact of added employment and population on 

social conditions on the Crow Reservation would be 

small. Some new personal and government income 

would be generated as discussed above. The effect of 

this new income on the Reservation would depend on a 

number of factors, including the extent to which 

Reservation members participate in the off-Reservation 

jobs or mineral ownership. Compared to other 

alternatives, oil and gas income could be less, 

depending on water treatment costs. See the Attitudes, 

Beliefs, Lifestyles and Values section under this 

alternative for additional information on social effects 

to Native Americans.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described above for Alternative E. 

Social and economic impacts would include creation of 

a limited number of new jobs in the Planning Area and 

related demographic shifts from people moving to the 

area. The impact of added employment and population 

on social conditions on the Northern Cheyenne 

Reservation would be small. Some new personal and 

government income would be generated as discussed 

above. The effect of this new income on the 

Reservation would depend on a number of factors, 

including the extent to which Reservation members 

participate in the off-Reservation jobs or mineral 

ownership. Compared to other alternatives, oil and gas 

income could be less, depending on water treatment 

costs. See the Attitudes, Beliefs, Lifestyles and Values

section under this alternative for additional information 

on social effects to Native Americans.
CHAPTER 4

Social and Economic Values

4-195

Social and economic impacts from CBNG 

development on federal lands would be mitigated as 

described in the Northern Cheyenne Mitigation 

Appendix. However, most measures focus on 

preventing the loss of tribal resources such as CBNG 

water. The BLM would consult with the tribe where 

site-specific analysis identifies social or economic 

impacts on the Reservation. 

The Northern Cheyenne Tribe can require their special 

socioeconomic mitigation measures in tribal leases on 

the reservation. 

Conclusions

Residual impacts would be similar to those for 

Alternative B, with the exception of the reduced 

impacts on lifestyles and values and water resource 

values that would result from the proposed measures to 

prevent the degradation of water resources.

Cumulative impacts would be somewhat less than for 

Alternative B, given the greater variety of control 

measures that would be used to prevent water resource 

impacts.

Alternative F—Phased Development 

Multiple Screens (High Range)

Because Alternative F would create fewer jobs 

annually and through completion of development than 

Alternatives B through E although wells would be 

drilled over a longer period of time, it is even more 

likely that jobs created under Alternative F would be 

filled by CBNG workers from Wyoming, as described 

in the Assumptions section. 

The following discussion quantifies impacts associated 

with full development within the crucial sage-grouse 

habitat areas. If no development occurs in these areas, 

the socioeconomic impacts such as jobs and revenues 

would be approximately 12.8 percent lower. While this 

scenario would reduce revenues and jobs to some 

degree, there would be less demand placed on 

infrastructure, schools and other public services. The 

overall effect of reducing development impacts in the 

crucial sage-grouse habitat are expected to be less than 

the 12.8 percent reduction.

Employment and Unemployment

Employment changes resulting from Alternative F are 

shown in Table 4-61 and are expected to be lower than 

Alternatives B through E. Employment for Alternative 

F may be slightly higher than shown, since a small 

number of additional jobs would be created to manage 

produced water from the federal CBNG wells. While 

the types of jobs generated under this alternative would 

be similar to those generated under Alternatives B-E, 

the number of jobs and rate of jobs created per year are 

predicted to vary from the other alternatives. The 

number of wells drilled per year under Alternative F 

would be more constant than for the Alternatives B-E 

and H and would extend for an additional three years. 

This would result in fewer new jobs created annually, 

but new jobs created annually over a longer period of 

time compared to Alternatives B-E and H. 

The numbers of jobs presented in Table 4-61 have 

been calculated on an annual basis. In year 1 of the 

development period, 217 new jobs are expected to be 

created to implement approved APDs. In year 2, 354 

jobs would be required; however, 217 of these jobs 

would likely be filled by the workers employed in year 

1. Consequently, the maximum number of workers 

needed in any one year would gradually increase over 

the development period from 217 to a peak of 1,039 in 

year 20, then gradually decrease as wells are 

abandoned. 

Over the 23-year phased development period, an 

annual average of 774 jobs would be created by this 

alternative. This breaks out to an annual average of 

243 initial development jobs, 523 production jobs and

8 well abandonment jobs created. There would be 

additional abandonment jobs after the development 

period (years 24 through 46). The total number of jobs 

created during the 23-year phased development period

under Alternative F would be 14,707, as compared to 

17,013 jobs during the 20-year development period for 

Alternatives B through E. The difference is mainly in 

the number of production jobs, which would be lower 

due to fewer producing wells per year as compared to 

other alternatives.

The effect of Alternative F on current unemployment

rates in the area would be less than for Alternatives B 

through E. There would be a potential for some 

residents in the Planning Area to obtain these new jobs 

if they have the appropriate skills, which would 

directly reduce unemployment. However, most of the 

jobs created would likely go to Wyoming CBNG 

workers. Consequently, most of the indirect effects of 

this new employment (wages spent on support 

services) are expected to occur in Wyoming.

Demographics

Employees working in the CBNG industry in the 

Montana portion of the Powder River Basin would 

likely be commuting from Wyoming. Most of the 

existing CBNG operations in Montana are located near 

Decker, Montana, with Sheridan, Wyoming (located 

approximately 20 miles away), the closest community 

with a population large enough to support CBNG 

operations. In addition, much of the proposed drilling 
Social and Economic Valuesl

CHAPTER 4

4-196

TABLE 4-61 

ALTERNATIVES F AND H: ESTIMATED WAGES AND JOBS FOR WELL DEVELOPMENT, PRODUCTION and ABANDONMENT (WAGES REPORTED IN 

CONSTANT DOLLARS)1

Year

Wells 

Drilled 

per 

Year

Initial 

Development 

Jobs1

Initial 

Development 

Wages1

Wells 

Producing 

Per Year2

Production 

Jobs1

Production 

Wages1

Wells 

Abandoned 

per Year2

Abandonment 

Jobs1

Abandonment 

Wages1

Estimated 

Total Jobs

Estimated 

New Jobs 

per Year

Estimated 

Total Wages

1 607 186 $5,390,919 546 31 $1,177,313 0 0 $0 217 217 $6,568,231

2 910 279 $8,081,938 1,336 75 $2,880,750 0 0 $0 354 137 $10,962,688

3 1074 329 $9,538,463 2,333 131 $5,030,531 0 0 $0 460 106 $14,568,994

4 1170 358 $10,391,063 3,386 190 $7,301,063 0 0 $0 549 89 $17,692,125

5 1074 329 $9,538,463 4,352 245 $9,384,000 0 0 $0 574 25 $18,922,463

6 910 279 $8,081,938 5,171 291 $11,149,969 0 0 $0 570 -4 $19,231,906

7 910 279 $8,081,938 5,991 337 $12,918,094 0 0 $0 616 46 $21,000,031

8 910 279 $8,081,938 6,810 383 $14,684,063 0 0 $0 662 46 $22,766,000

9 910 279 $8,081,938 7,628 429 $16,447,875 0 0 $0 708 46 $24,529,813

10 910 279 $8,081,938 8,447 475 $18,213,844 0 0 $0 754 46 $26,295,781

11 910 279 $8,081,938 9,266 521 $19,979,813 0 0 $0 800 46 $28,061,750

12 906 277 $8,046,413 10,081 567 $21,737,156 0 0 $0 845 45 $29,783,569

13 824 252 $7,318,150 10,823 609 $23,337,094 0 0 $0 861 17 $30,655,244

14 824 252 $7,318,150 11,565 651 $24,937,031 0 0 $0 903 42 $32,255,181

15 824 252 $7,318,150 12,307 692 $26,536,969 0 0 $0 945 42 $33,855,119

16 704 216 $6,252,400 12,941 728 $27,904,031 0 0 $0 944 -1 $34,156,431

17 703 215 $6,243,519 13,574 764 $29,268,938 0 0 $0 979 35 $35,512,456

18 654 200 $5,808,338 14,163 797 $30,538,969 0 0 $0 997 18 $36,347,306

19 543 166 $4,822,519 14,652 824 $31,593,375 0 0 $0 990 -6 $36,415,894

20 444 136 $3,943,275 15,052 847 $32,455,875 0 0 $0 983 -8 $36,399,150

21 509 156 $4,520,556 14,964 842 $32,266,125 546 41 $1,416,966 1,039 56 $38,203,647

22 496 152 $4,405,100 14,590 821 $31,459,688 819 61 $2,124,281 1,034 -5 $37,989,069

23 499 153 $4,431,744 14,072 792 $30,342,750 967 72 $2,507,119 1,017 -17 $37,281,613

23-Year 

Total

18,225 5,121

$161,860,781

9,586

$461,545,313

2,332 175

$6,048,366

14,707

$629,454,459

Annual 

Average

792 243

$7,037,425

523

$20,067,188

101 8

$262,972

774

$27,367,585

NOTES:

1

Numbers of jobs and wages were calculated using the same method as Table 4-58. The numbers of jobs have been calculated on an annual basis. The maximum number of workers needed in any one year 

would gradually increase over the development period from 217 to a peak of 1.039 in year 20, then gradually decrease as the wells are abandoned.

2

Numbers of production and abandonment wells are based on the assumption that 10% of all wells drilled would be dry holes.
CHAPTER 4

Social and Economic Values

4-197

in Montana would occur in four watersheds: Middle

Powder River, Lower Powder River, Upper Tongue 

River and Lower Tongue River. These areas are 

located in the general vicinity of Sheridan, Buffalo and 

Gillette, Wyoming. 

New temporary jobs related to CBNG could be created 

by drilling and construction activities, or the 

application of technology that requires additional 

employees, while new permanent jobs could be created 

to oversee additional production wells and facilities.

The available jobs range from laborers and other field 

positions to technical/professional positions, such as 

geologists and engineers and other office staff 

positions. Additional support jobs could include 

surveyors and research scientists. 

Most of the subcontracting companies used by CBNG 

companies operating in Montana are based in 

Wyoming. A small number of subcontracting 

companies and individual workers are from Montana. 

Job opportunities related to CBNG are advertised in 

both the Wyoming and Montana state job databases.

Social Organization

Housing Units and Vacancy

Most employees would commute from Wyoming, thus 

there would be little additional demand for housing in the 

Planning Area due to implementation of Alternative F.

Public Services and Utilities

Similarly, this alternative would have little effect on 

public services and utilities in the Planning Area, since 

most of the workers would be living in Wyoming 

rather than the Planning Area. The communities of 

Sheridan, Gillette and Buffalo, Wyoming, would most 

likely be affected by additional employees needed to 

support CBNG operations in the area of Montana with 

the greatest potential for CBNG development. 

Cumulative impacts to Wyoming communities are 

discussed in the Impacts from Management Common 

to All Alternatives section.

Attitudes, Beliefs, Lifestyles and Values

General impacts on population subgroups such as 

farmers, ranchers, small town residents, Native 

Americans and retirees, would be similar but are likely 

to have less effect than Alternatives B through E, 

particularly in the short-term (years 1-5 of the 

development period). Effects could include conflict 

with the attitudes, beliefs, lifestyles and values of 

many individuals. Drilling, testing and operation of 

CBNG wells would result in increased traffic from 

trucks and other vehicles; noise from traffic and the 

operation of generators and drilling and other 

equipment; visual resource impacts from the 

construction of the wells themselves, as well as power 

lines and related electrical infrastructure; and 

psychological stress associated with unwanted change, 

division in the community, or other impacts. The 

population subgroups would be affected to the degree 

to which their lifestyles and values are inconsistent 

with such impacts.

The majority of individuals in the Planning Area are 

understood to have traditional rural lifestyles in which 

the relatively quiet and pristine surroundings are an 

important value. They could find CBNG development 

inconsistent with the desired balance between 

environmental stewardship and economic development 

expressed in many of the scoping comments and 

newspaper reports. This would be particularly true for 

Big Horn, Powder River and Rosebud counties where 

the majority of the wells would be developed. Largescale CBNG development could be viewed as part of a 

gradual transition away from traditional rural and 

agricultural lifestyles. Some people in the area who are 

more interested in the potential economic benefits of 

CBNG development would likely perceive or 

experience fewer impacts with respect to lifestyles and 

values.

Large-scale CBNG development is likely to conflict to 

some degree with traditional Native American values 

which emphasize preservation of cultural heritage and 

a reverence for the natural environment. Native 

American groups could be affected by increases in 

noise, impacts on visual resources and plant 

populations, etc., in particular as these affect locations 

and resources used for spiritual or religious purposes. 

It is assumed that no CBNG wells would be developed 

on the Native American reservations initially and

therefore impacts would be more likely to affect those 

individuals living off the reservations or whose 

activities are conducted off the reservations. Native 

American development is considered as part of the 

cumulative effects impact potential. It is likely that a 

smaller number of Native Americans who are 

interested in the development of energy resources 

would perceive or experience fewer harmful impacts 

from CBNG development.

Impacts on recreation areas would include the loss of 

land for recreation purposes and the disruption to 

recreation activities. Each well would present its own 

set of unique circumstances that would require

mitigation to minimize impacts. Exploratory activities, 

such as drilling and testing, would temporarily displace 

game species locally. Less recreation area would likely 

be disturbed under Alternative F because the maximum 

level of federal well development would be limited in 
CHAPTER 4

Social and Economic Values

4-198

each watershed and habitat disturbance would be 

limited. 

The use of watershed-level analysis, water management 

plans and water balance projections as part of PODs 

would reduce the amount of erosion and water quality 

impacts expected from surface discharge of produced 

water. By use of watershed-level management of surface 

discharged water (i.e., 10 percent of 7Q10), impacts to 

surface water would be less than Alternative C and 

likely less than Alternative E.

The main difference under Alternative F would be that 

by limiting the number of federal wells approved each

year per watershed, the overall rate of well 

development would be slower than for Alternatives B 

through E, especially in those areas where the greatest 

level of drilling would occur (the Upper Tongue, 

Lower Tongue and Middle Powder watersheds). For 

example, in year 4 (the year with the highest number of 

predicted wells), 2,200 wells would be drilled under 

Alternatives B through E versus 1,170 wells under 

Alternative F. While initial development under 

Alternatives B through E would likely be concentrated 

near areas that have already been developed, 

watershed-based limits under Alternative F would 

require development to be more dispersed among 

watersheds. Based on this more even development 

over time and among watersheds, combined with the 

20/20 crucial habitat screen, the amount of habitat 

disturbance and fragmentation from federal wells 

would also be limited within each watershed. 

This more even pace of development and restricted 

place of development may help residents adjust to the 

influx of CBNG development, but the impacts could 

last longer than under Alternatives B through E. Early 

in the phased development period, specific sources of 

noise, visual intrusion and surface disturbance would 

be less each year per watershed under this alternative 

than under Alternatives B through E because of the 

limits placed on approval of federal wells. In the later 

years of the development period, the sources of 

disturbance would be greater for this alternative as 

more federal wells would be developed than under 

Alternatives B through E. However, residents in the 

areas of CBNG development would still be impacted 

by any activities approved by the state. 

Personal Income

Estimated CBNG wages for Alternative F are shown in 

Table 4-61. These wages would add to the total 

personal income mainly in the localities where 

employees reside (Wyoming). Wages would be 

produced from the development, production and

abandonment phases. The estimated total wages over 

the phased development period would be 

$629,454,459. Annual wages are estimated to be 

$27,367,585, but would range from $6.6 million in 

year 1 to $38.2 million in year 21. 

Income would also be generated by those who own the 

land or the mineral rights as described for Alternative 

A. Purchases made with CBNG income would produce 

some additional indirect income in the region as wages 

circulate through the economy. Most income from 

wages would likely be spent in Wyoming, where most 

CBNG workers live and income from land and mineral 

rights would likely be spent in Montana, where 

landowners live.

Government Revenues

Oil and Gas Income

Assuming that of the 18,225 wells drilled, 

approximately 10 percent would be dry holes leaving

approximately 16,403 wells to generate production 

income. Production income under Alternative F would 

be expected to be lower than Alternatives B through E 

for years 3 through 17 and higher in the other years 

due to the limited number of APDs allocated per year.

Using the same production income as Alternative B, 

gross production income per year of operation would 

be approximately $182,500 per well. The number of 

producing wells would range from 546 in year 1 to 

15,052 in year 20 (see Table 4-61). It follows that 

estimated annual gross income would range from $100 

million (year 1) to $2.7 billion (year 20). Royalty 

income of 12.5 percent would range from $12 million 

(year 1) to $343 million (year 20), as compared to $12 

to $322 million for Alternatives B through E. The 

maximum annual number of producing wells for this 

alternative would be higher than for Alternatives B 

through E (15,052 in year 20 versus 14,100 in year 18). 

Distribution of production and royalty income to BLM, 

state (private) minerals and private minerals and 

income from rents and leases for oil and gas 

development would be similar to Alternative B. 

Generally, new state revenues from CBNG would be 

substantial. This source of state revenue would be 

more evenly spread over the phased development

period under Alternative F as compared to Alternatives 

B through E. This would be a more constant source of 

income for the state, rather than a large infusion of 

revenue early in the program (years 1-5) that would 

dwindle over time. 

Similar to Alternative B, government revenue from oil 

and gas would be reduced by costs for monitoring and 

regulating CBNG activity and water treatment. 

However, these costs are relatively small as compared 

to the generated revenue.
CHAPTER 4

Social and Economic Values

4-199

Under Alternative F, the Crow and Northern Cheyenne 

reservations would be protected from drawdown of 

coal seam aquifers and drainage of tribal CBNG and 

groundwater resources by the establishment of a 5-mile 

buffer zone around the borders of the reservations. If 

the development of federal minerals within the 5-mile 

buffer zone is delayed or restricted while development 

on state and private leases continue, then the situation 

develops where there would be the increased potential 

for drainage of federal minerals. Within the 5-mile 

buffer zone of reservation boundaries, BLM managed 

minerals represent 24 percent (127,165 acres) of total 

mineral ownership (463,118 acres) within the Billings 

RMP Area and 64 percent (250,565 acres) of total 

mineral ownership (355,307 acres) within the Powder 

River RMP Area. These federal minerals could contain 

as much as 1.4 to 1.6 TCF of gas that may be lost to 

the federal, state and county governments [(127,165 ac

+ 250,565 ac)/1 well site per 80 acres * 0.3 to 0.34 

BCF per well site]. The loss of royalties to the Federal 

government would be approximately $1.2 billion at 

current gas prices.

Alternative F differs from other alternatives in that 

Federal revenues and the associated state revenues, 

could be reduced if operators and BLM cannot find 

economic means of developing within the crucial sagegrouse habitat areas. If this transpires, then overall 

Federal royalties would be reduced by approximately 

$299,000,000 over the life of the field development. 

Similarly, private and State mineral estates may lose 

approximately $100,000,000 in royalties, assuming a 

similar royalty rate is paid to these mineral estate 

owners.

Taxes

Income Taxes

Income taxes would be somewhat lower than 

Alternative B due to the lower average number of 

estimated jobs (851 versus 774 jobs per year). 

However, since most of the workers are expected to 

come from Wyoming, it is likely that most of the 

income taxes generated by CBNG development would 

be paid in Wyoming. 

Property Taxes

Like Alternatives B through E, property taxes would 

accrue to counties roughly in proportion to the number 

of new wells. Big Horn, Powder River and Rosebud 

counties would have the vast majority of new wells; 

therefore, they would be anticipated to experience the 

greatest increases in assessed values and the greatest 

increase in new county property tax revenues. These 

new revenues could help improve schools, roads, 

community services and other county assets, after 

accounting for any new costs associated with CBNG.

There could be some slight difference between these 

alternatives related to which counties would accrue 

these taxes. This may be caused by focusing CBNG 

development by watersheds instead of other 

jurisdictional boundaries. 

Natural Resources Taxes

Like the other alternatives, the products of natural 

resource extraction in Montana, including natural gas, 

are subject to state natural resource taxes, including 

local government severance taxes. Any new production 

of natural gas would be subject to such taxes. 

Severance taxes are distributed to a variety of state and 

local funds and would contribute positively to the state 

and local economies.

Other Taxes

The local and state economies would benefit from 

sales of goods and services by local businesses to oil 

and gas operators associated with the project.

However, local sales of goods and services associated 

with CBNG development would not generate increases 

in tax revenues because there is no sales tax in 

Montana. In addition, most of the purchases associated 

with CBNG would likely be made in Wyoming.

Water Resource Values

Alternative F would have impacts on water resources 

and water resource values similar to Alternative E. 

However, disposal under this alternative would be 

managed on a watershed basis to reduce water quality

impacts that may adversely affect downstream water 

users. Alternative H would allow limited discharge of 

untreated water under certain conditions. The volume 

of discharge from federal wells would be based on 10 

percent of the 7Q10 flow calculated from all CBNG 

wells at the downstream end of the watershed. If this 

10 percent limit is being used by state or private wells, 

then no additional discharge of untreated water would 

be allowed from federal wells. Water produced by 

federal wells may be treated, used for beneficial uses, 

or re-injected into the ground if the 10 percent 

allowable discharge has already been exceeded. 

Discharge of produced water into state waters would 

be allowed only under an approved State permit which 

would protect existing uses. Produced water put to 

beneficial use would provide an economic benefit to 

affected water users.

As for Alternatives B though E, localized groundwater 

drawdown would occur over time. The risk of such 

drawdown would likely be greater than Alternative B, 
CHAPTER 4

Social and Economic Values

4-200

since reinjection of all produced water is not required 

under this alternative. However, water well mitigation

agreements would address the potential reduction or 

loss of water resources and provide for prompt 

supplementation or replacement of water from any 

nearby natural spring or water well adversely affected 

by a CBNG well.

Crow Reservation

With lower numbers of jobs expected, Alternative F 

would result in somewhat lower social and economic

impacts on the Crow Reservation as compared to

Alternatives B through E. Similar to other Montana 

residents, unless Crow tribal members are already 

working in the CBNG industry out of Wyoming, it is 

unlikely that tribal members would fill the jobs created 

by Alternative F. 

Alternative F requires monitoring of federal CBNG 

development within 5 miles of the Crow Reservation. 

Site-specific groundwater and air quality analysis and 

mitigation measures would be required and 

implemented through the operator’s Plan of 

Development. ITAs would be protected from federal 

CBNG wells located within 5 miles of the Crow 

Reservation and if analysis showed that ITAs would be 

adversely affected, then BLM would consult with the 

tribe and determine appropriate mitigation measures 

which may include not approving the APDs. BLM 

would require groundwater monitoring wells and air 

monitoring between the federal well field development 

area and the reservation. If this monitoring indicates 

ITAs are not being protected, then the wells would be 

shut in.

CBNG workers needing to travel from Sheridan or 

Gillette to the potential CBNG sites in the western part 

of the Planning Area would likely avoid traveling 

across the Crow Reservation by driving from Sheridan 

to Lovell, Wyoming or travel north from Powell, 

Wyoming or travel south from Billings, Montana. 

However, if CBNG development occurs on the Crow 

Reservation workers from Wyoming would enter the 

Crow Reservation.

Northern Cheyenne Reservation

Due to a lower number of new jobs expected and the 

fact that CBNG workers will not be crossing the 

Northern Cheyenne Reservation on their journey to 

work, except for the wells developed in the northern 

portion of the Planning Area, Alternative F would 

likely result in somewhat lower impacts on the 

Northern Cheyenne Reservation related to population, 

employment and social conditions as Alternatives B 

through E. Like other Montana residents, unless 

Northern Cheyenne tribal members are already 

working in the CBNG industry out of Wyoming, it is 

unlikely that tribal members would fill the jobs created 

by Alternative F. Some off-site members may be

encouraged by perceived job opportunities to return to 

the Reservation, which could increase demand for 

public services. Some tribe members are concerned 

that increased stress caused by social changes due to 

CBNG development may also increase the likelihood 

of alcoholism, drug abuse and family violence. 

Alternative F would require monitoring of federal 

CBNG development within 5 miles of the Northern 

Cheyenne Reservation. These requirements would 

protect ITAs and include site-specific groundwater and 

air quality analysis. This analysis would be included in 

the operator’s Plan of Development. ITAs would be 

protected from federal CBNG wells located within 5 

miles of the Northern Cheyenne Reservation and if 

analysis showed that ITAs would be adversely 

affected, then BLM would consult with the tribe and 

determine appropriate mitigation measures which may 

include not approving the APDs. BLM would require 

groundwater and air monitoring between the federal 

well field development area and the Reservation. If this 

monitoring indicates ITAs are not being protected, 

then the wells would be shut in.

CBNG operators and subcontractors may need to drive 

across the Northern Cheyenne Reservation to reach 

some well sites in the northern part of the Planning 

Area (Rosebud County). Although the number of wells 

to be developed north of the Northern Cheyenne 

Reservation is relatively small, limited traffic, noise, 

safety and road maintenance impacts could occur on 

the reservation. The Northern Cheyenne are concerned 

that this would increase tribal member contact with 

outsiders, increasing the negative effects of social 

change described above. However, there is little reason 

for CBNG workers to stop on the reservation, as few 

services are offered on the reservation routes that 

would be used. Interaction with commuting workers

would be of short duration and sporadic. 

Conclusions 

Social and economic impacts, such as employment, 

income, demographic migration, taxes, changes in 

lifestyle and social conditions would likely be less than

to those for Alternative B through E and there is less 

likely to be a “boom and bust” cycle associated with 

Alternative F. Like the other alternatives, new jobs 

would likely be filled by CBNG workers from 

Wyoming. Under this alternative, CBNG development 

would be relatively steady over the phased

development period, provided development continues 

and the demand for natural gas remains. Under the 
CHAPTER 4

Social and Economic Values

4-201

other development alternatives, CBNG development 

would increase rapidly, peaking over a 5-year period

and then decrease over the remainder of the 

development period. In addition, the social and 

economic impacts are likely to vary slightly from the 

other alternatives because development would occur 

based on watersheds, which may further spread CBNG 

development outside the three main counties most 

affected under Alternatives B through E (Big Horn, 

Powder River and Rosebud). This may reduce the 

overall impacts on social conditions and lifestyles. 

The cumulative reduction in federal royalties due to 

the conditions placed on development within crucial 

sage-grouse habitat areas coupled with the 5-mile 

buffer development delay/restriction around 

reservations would result in a $1.5 billion loss to the 

federal government at current gas prices.

Cumulative water resource impacts from Alternative F 

would be less than Alternative C and E and more than 

Alternative B.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Under Alternative G, fewer jobs would be created 

annually and through completion of development of all 

the Alternatives considered. Although wells would be 

drilled over a longer period of time, it is even more 

likely that jobs created under Alternative G would be 

filled by CBNG workers from Wyoming, as described 

in the Assumptions section. 

Employment and Unemployment

CBNG employment under Alternative G is shown in 

Table 4-62 and would be similar (in the types of job 

opportunities) to Alternatives B through F. However, 

this alternative would result in a substantially lower 

number of new jobs, approximately 65 percent fewer 

jobs on average. The numbers of jobs presented in 

Table 4-62 have been calculated on an annual basis. In 

year 1 of the development period, 77 new jobs are 

expected to be created to implement approved APDs. 

In year 2, 126 jobs would be required; however, 77 of 

these jobs would likely be filled by the workers 

employed in year 1. Consequently, the maximum 

number of workers needed in any one year would 

gradually increase over the development period from 

77 to a peak of 369 in year 21, then gradually decrease 

as wells are abandoned.

Under Alternative G, over the phased development 

period, an annual average of 275 jobs would be 

created. This breaks out to an annual average of 86

initial development jobs, 186 well production jobs and

3 well abandonment jobs. After the 23-year 

development period (years 24 through 46), there would 

be additional abandonment jobs. The total number of 

jobs created during the 23-year phased development 

period under Alternative G would be 6,323, as 

compared to 14,707 jobs during the 23-year phased 

development period under Alternative F and 17,013 

jobs during the 20-year development period under 

Alternatives B through E. 

Similar to other alternatives, limited phased CBNG 

development would create some new jobs for persons 

with the appropriate skills. However, the number of 

jobs created would be substantially less than the other 

development alternatives and it is not likely that this 

alternative would have a large effect on unemployment

in the area as compared to other development 

alternatives. 

Demographics

The type of effects from this alternative on 

demographics would be similar to Alternative F, while 

the amount of change would be less due to 

substantially fewer new jobs. As described under 

Alternative F, employees working in the CBNG 

industry in the Montana portion of the Powder River

Basin would likely commute from Wyoming.

Most of the subcontracting companies used by CBNG 

companies operating in Montana are based in 

Wyoming. A small number of subcontracting 

companies and individual workers are from Montana. 

Job opportunities related to CBNG are advertised in 

both the Wyoming and Montana state job databases.

Social Organization

Housing Units and Vacancy

Like Alternative F, most employees under Alternative 

G would commute from Wyoming; thus, there would 

be little additional demand for housing in the Planning 

Area. 

Public Services and Utilities

Similarly, this alternative would have little effect on 

public services and utilities within the Planning Area, 

since most of the workers would be living in Wyoming

rather than the Planning Area. The highway connecting 

Sheridan to Decker would receive the most vehicle 

traffic related to CBNG operations in Montana.

The types of effects on public services and utilities 

would be similar to Alternative F, but less due to the 

lower number of expected new jobs. The communities 

of Sheridan, Gillette and Buffalo, Wyoming, would

most likely be called upon to provide public services. 
Social and Economic Valuesl

CHAPTER 4

4-202

TABLE 4-62 

ALTERNATIVE G: ESTIMATED WAGES AND JOBS FOR WELL DEVELOPMENT, PRODUCTION and ABANDONMENT (WAGES REPORTED IN 

CONSTANT DOLLARS)1

Year

Wells 

Drilled 

per 

Year

Initial 

Development 

Jobs1

Initial 

Development 

Wages1

Wells 

Producing 

Per Year2

Production 

Jobs1

Production 

Wages1

Wells 

Abandoned 

per Year2

Abandonment 

Jobs1

Abandonment 

Wages1

Estimated 

Total Jobs

Estimated 

New Jobs 

per Year

Estimated 

Total Wages

1 215 66 $1,909,469 194 11 $418,313 0 0 $0 77 77 $2,327,781

2 323 99 $2,868,644 486 27 $1,047,938 0 0 $0 126 50 $3,916,581

3 381 117 $3,383,756 829 47 $1,787,531 0 0 $0 163 37 $5,171,288 

4 415 127 $3,685,719 1,204 68 $2,596,125 0 0 $0 195 32 $6,281,844

5 381 117 $3,383,756 1,547 87 $3,335,719 0 0 $0 204 9 $6,719,475

6 323 99 $2,868,644 1,838 103 $3,963,188 0 0 $0 202 -1 $6,831,831

7 323 99 $2,868,644 2,129 120 $4,590,656 0 0 $0 219 16 $7,459,300

8 323 99 $2,868,644 2,420 136 $5,218,125 0 0 $0 235 16 $8,086,769

9 323 99 $2,868,644 2,711 152 $5,845,594 0 0 $0 251 16 $8,714,238

10 323 99 $2,868,644 3,002 169 $6,473,063 0 0 $0 268 16 $9,341,706

11 323 99 $2,868,644 3,294 185 $7,102,688 0 0 $0 284 16 $9,971,331

12 322 99 $2,859,763 3,583 202 $7,725,844 0 0 $0 300 16 $10,585,606

13 293 90 $2,602,206 3,846 216 $8,292,938 0 0 $0 306 6 $10,895,144

14 293 90 $2,602,206 4,110 231 $8,862,188 0 0 $0 321 15 $11,464,394

15 293 90 $2,602,206 4,373 246 $9,429,281 0 0 $0 336 15 $12,031,488

16 250 77 $2,220,313 4,598 259 $9,914,438 0 0 $0 335 -1 $12,134,750

17 250 77 $2,220,313 4,823 271 $10,399,594 0 0 $0 348 13 $12,619,906

18 232 71 $2,060,450 5,033 283 $10,852,406 0 0 $0 354 6 $12,912,856

19 193 59 $1,714,081 5,206 293 $11,225,438 0 0 $0 352 -2 $12,939,519

20 158 48 $1,403,238 5,347 301 $11,529,469 0 0 $0 349 -3 $12,932,706

21 181 55 $1,607,506 5,316 299 $11,462,625 194 15 $501,891 369 20 $13,572,022

22 176 54 $1,563,100 5,182 291 $11,173,688 291 22 $754,003 367 -2 $13,490,791

23 177 54 $1,571,981 4,998 281 $10,776,938 343 26 $889,397 361 -6 $13,238,316

23-Year 

Total

6,470 1,982

$57,470,569

4,279

$164,023,781

827 62

$2,145,291

6,323

$223,639,641

Annual 

Average

281 86

$2,498,720

186

$7,131,469

36 3

$93,274

275

$9,723,463

NOTES:

1

Numbers of jobs and wages were calculated using the same method as Table 4-58. The numbers of jobs have been calculated on an annual basis. The maximum number of workers needed 

in any one year would gradually increase over the development period from 77 to a peak of 369 in year 21, then gradually decrease as the wells are abandoned. 2

Numbers of production and abandonment wells are based on the assumption that 10% of all wells drilled would be dry holes.
CHAPTER 4

Social and Economic Values

4-203

emergency services and support services for 

employees and their families.

Cumulative impacts to Wyoming communities are 

discussed in the Impacts from Management Common 

to All Alternatives section 

Attitudes, Beliefs, Lifestyles and Values

The type of impacts on population subgroups such as 

farmers, ranchers, small town residents, Native 

Americans, retirees under Alternative G would be 

similar to Alternative F. However, this alternative is 

anticipated to have a greatly reduced effect on 

attitudes, values, beliefs and lifestyles as compared to 

other alternatives (see below for details). Not only is 

the location of development more restricted than 

Alternatives B through E (Alternative G is similar to 

Alternative F in that well location development is 

restricted by watershed), but the pace of development 

is greatly reduced even over Alternative F. Thus, under 

Alternative G, noise, visual impacts and surface 

disturbance would be minimized as compared to the 

other alternatives. In addition, less recreational or 

habitat areas would be disturbed. 

Although Alternative G would have fewer effects on 

attitudes, values, beliefs and lifestyles, the 

development of CBNG wells would still result in 

increased traffic from trucks and other vehicles; noise 

from traffic and the operation of generators and 

drilling and other equipment; visual resource impacts 

from the construction of the wells themselves as well 

as power lines and related electrical infrastructure; and 

psychological stress associated with unwanted change,

division in the community, or other impacts. The 

population subgroups would be affected to the degree 

to which their lifestyles and values are inconsistent 

with such impacts.

The majority of individuals in the Planning Area are 

understood to have traditional rural lifestyles in which 

the relatively quiet and pristine surroundings are an 

important value. They could find CBNG development 

inconsistent with the desired balance between 

environmental stewardship and economic development 

expressed in many of the scoping comments and 

newspaper reports, although they may find Alternative 

G more acceptable. Some people in the area who are 

more interested in the potential economic benefits of 

CBNG development would likely perceive or 

experience fewer impacts with respect to lifestyles and 

values.

Alternative G may be more acceptable with Native 

Americans and may conflict less with traditional 

Native American values, which emphasize 

preservation of cultural heritage and a reverence for 

the natural environment. However, Native American 

groups could still be affected by increases in noise, 

impacts on visual resources and plant populations, etc., 

in particular as these affect locations and resources 

used for spiritual or religious purposes. It is assumed 

that no CBNG wells would be developed on the Native 

American reservations initially and therefore impacts 

would be more likely to affect those individuals living 

off the reservations or whose activities are conducted 

off the reservations. Native American development is 

considered as part of the cumulative effects impact 

potential. It is likely that a smaller number of Native 

Americans who are interested in the development of 

energy resources would perceive or experience fewer 

harmful impacts from CBNG development.

Impacts on recreation areas would include the loss of 

land for recreation purposes and the disruption to 

recreation activities. Each well would present its own 

set of unique circumstances that would require

mitigation to minimize impacts. Exploratory activities, 

such as drilling and testing, would temporarily displace 

game species locally. Less recreation area would likely 

be disturbed under Alternative G than the other 

Alternatives. 

As for Alternative F, the use of watershed-level 

analysis, water management plans and water balance 

projections as part of PODs would reduce the amount 

of erosion and water quality impacts expected from 

surface discharge of produced water. By use of 

watershed-level management of surface discharged 

water (i.e., 10 percent of 7Q10), as well as a lower 

level of development, impacts to surface water would 

be less than Alternatives C, E and F. 

More than any other alternative, Alternative G limits

the number of federal wells approved each year per 

watershed, so the overall rate of well development 

would be slower than for Alternatives B through F, 

especially in those areas where the greatest level of 

drilling would occur, such as the Upper Tongue, 

Lower Tongue and Middle Powder watersheds. For 

example, in year 4 (the year with the highest number of 

predicted wells), 2,200 wells would be drilled under 

Alternatives B through E versus 416 wells under 

Alternative G. The number of federal wells and the 

amount of habitat disturbance and fragmentation from 

federal wells would also be limited in each watershed. 

This lower level and more even pace of development 

and restricted place of development may help residents 

adjust to the influx of CBNG development, but the 

impacts could last longer than under Alternatives B 

through E. Throughout the phased development period, 

specific sources of noise, visual intrusion and surface 

disturbance would be less each year per watershed 

under this alternative than the other development 
CHAPTER 4

Social and Economic Values

4-204

alternatives. However, residents in the areas of CBNG 

development would still be impacted by any activities 

approved by the State. 

Personal Income

The estimated wages for Alternative G are shown in 

Table 4-62. Similar to other development alternatives, 

the wages earned from CBNG development would 

directly increase personal income for those working in 

the CBNG industry and indirectly increase personal 

income for persons working in other economic sectors 

where CBNG workers may spend income. Like the 

other alternatives, most of the direct and indirect 

income would go to workers in Wyoming. The 

predicted total wages over the phased development 

period for Alternative G would be $223,639,641. As 

compared to Alternative F, this alternative would 

produce approximately 35 percent as much personal 

income ($629,454,459 versus $223, 639,641). Income 

would also be generated by persons who own the land 

or mineral rights where drilling would occur similar to 

Alternative A.

Government Revenues

Oil and Gas Income

Assuming that 10 percent of the 6,470 wells drilled 

under this alternative would be dry holes, 

approximately 5,822 wells would remain to generate 

production income. Using the same production income 

ratio as Alternative B, gross production income per 

year of operation would be approximately $182,500 

per well. The number of producing wells would range 

from 194 in year 1 to 5,341 in year 20 (see Table 

4-62). It follows that estimated annual gross income 

would range from $35 million (year 1) to $976 million 

(year 20). Royalty income of 12.5 percent would range 

from $4.4 million (year 1) to $12 million (year 20). 

The oil and gas income generated under Alternative G 

would be significantly less than other development 

alternatives as income for other development 

alternatives is as high as $2.7 billion. 

Taxes

Income Taxes

The estimated average yearly income tax revenue 

generated by Alternative G would be $289,000, 

assuming a three percent tax rate. Alternative G would 

generate $605,000 less tax revenue than Alternatives B

through E and $524,000 less than Alternative F.

However, since most of the jobs are expected to be 

filled by workers living in Wyoming, most of these 

taxes would likely be paid in Wyoming.

Property Taxes

Like Alternatives B through F, property taxes would 

accrue to counties roughly in proportion to the number 

of new wells. Big Horn, Powder River and Rosebud

counties would have the majority of new wells; 

therefore, they would be anticipated to experience the 

greatest increases in assessed values and the greatest 

increase in new county property tax revenues. These 

new revenues could help improve schools, roads, 

community services and other county assets, after 

accounting for any new costs associated with CBNG. 

Property taxes would be lower for Alternative G than 

the other alternatives because fewer wells would be 

developed. Similar to Alternative F, which would 

focus CBNG development by watershed instead of 

other jurisdictional boundaries, there could be some 

differences related to which counties accrue the taxes. 

Natural Resources Taxes

Like the other alternatives, the products of natural 

resource extraction in Montana, including natural gas, 

are subject to state natural resource taxes, including 

local government severance taxes. Any new production 

of natural gas would be subject to such taxes. 

Severance taxes are distributed to a variety of state and 

local funds and would contribute positively to the state 

and local economies. Natural Resources taxes would 

be lower for Alternative G than the other alternatives 

because fewer wells would be developed. There could 

be some slight difference between these alternatives 

related to which counties would accrue these taxes. 

This may be caused by limiting CBNG development 

by watershed instead of other jurisdictional boundaries. 

Other Taxes

The local and state economies would benefit from 

sales of goods and services by local businesses to oil 

and gas operators associated with the project.

However, local sales of goods and services associated 

with CBNG development would not generate increases 

in tax revenues because there is no sales tax in 

Montana. In addition, most of the purchases associated 

with CBNG would likely be made in Wyoming 

Water Resource Values

Alternative G would produce less water, but due to 

discharge limitations, it would likely have impacts on 

water resources and water resource values similar to 

Alternatives C, D, E and F. Like Alternative F, this 

alternative would allow limited discharge of untreated 

water under certain conditions. The volume of 

discharge from federal wells would be based on 10 

percent of the 7Q10 flow calculated from all CBNG 
CHAPTER 4

Social and Economic Values

4-205

wells at the downstream end of the watershed. If this 

10 percent limit is being used by state or private wells, 

then no additional discharge of untreated water would

be allowed from federal wells. Water produced by 

federal wells may be treated, used for beneficial uses, 

or re-injected into the ground if the 10 percent 

allowable discharge has already been exceeded. 

Discharge of produced water into State waters would 

be allowed only under an approved State permit which 

would protect existing uses. Produced water put to 

beneficial use would provide an economic benefit to 

affected water users.

As for Alternatives B though F, localized groundwater 

drawdown would occur over time. The risk of such 

drawdown would likely be greater than Alternative B, 

since reinjection of all produced water is not required 

under this alternative, but less than Alternatives C 

through F due to the reduced level of development. 

Water well mitigation agreements would address the 

potential reduction or loss of water resources and 

provide for prompt supplementation or replacement of 

water from any nearby natural spring or water well 

adversely affected by a CBNG well.

Crow Reservation

The types of social and economic impacts of 

Alternative G on the Crow Reservation would be 

similar to Alternative F. However, the magnitude of 

impacts would be lower with fewer expected new jobs. 

Similar to other Montana residents, unless Crow tribal 

members are already working in the CBNG industry 

out of Wyoming, it is unlikely that tribal members 

would fill jobs created by Alternative G.

Similar to Alternative F, Alternative G would require 

monitoring of federal CBNG development within 5 

miles of the Crow Reservation. Site-specific 

groundwater and air quality analysis and mitigation

measures would be required and implemented through 

the operator’s Plan of Development. ITAs would be 

protected from federal CBNG wells located within 5 

miles of the Crow Reservation and if analysis showed 

that ITAs would be adversely affected, then BLM 

would consult with the tribe and determine appropriate 

mitigation measures which may include not approving 

the APD. BLM may require groundwater monitoring 

wells and air monitoring between the federal well field 

development area and the reservation. If this 

monitoring indicates ITAs are not being protected, 

then the wells would be shut in. 

CBNG workers needing to travel from Sheridan or 

Gillette to the potential CBNG sites in the western part 

of the Planning Area would likely avoid traveling 

across the Crow Reservation by driving from Sheridan 

to Lovell, Wyoming or travel north from Powell, 

Wyoming or travel south from Billings, Montana. 

However, if CBNG development occurs on the Crow 

Reservation, workers from Wyoming would enter the 

Crow Reservation.

Northern Cheyenne Reservation

The types of social and economic impacts of

Alternative G on the Northern Cheyenne Reservation

would be similar to Alternative F, although the amount 

of impacts would be lower due to fewer expected new 

jobs. Similar to other Montana residents, unless 

Northern Cheyenne tribal members are already 

working in the CBNG industry out of Wyoming, it is 

unlikely that tribal members would fill jobs created by 

Alternative F. Some off-site members may be 

encouraged by perceived job opportunities to return to 

the Reservation, which could increase demand for 

public services. Some tribe members are concerned 

that increased stress caused by social changes due to 

CBNG development may also increase the likelihood 

of alcoholism, drug abuse and family violence. 

Similar to Alternative F, Alternative G would require 

monitoring of federal CBNG development within 5 

miles of the Northern Cheyenne Reservation. Sitespecific groundwater and air quality analysis and 

mitigation measures would be required and 

implemented through the operator’s Plan of 

Development. ITAs would be protected from federal 

CBNG wells located within 5 miles of the Northern 

Cheyenne Reservation and if analysis showed that 

ITAs would be adversely affected, then BLM would 

consult with the tribe and determine appropriate 

mitigation measures which may include not approving 

the APD. BLM may require groundwater monitoring 

wells and air monitoring between the federal well field 

development area and the reservation. If this 

monitoring indicates ITAs are not being protected, 

then the wells would be shut in. 

Like Alternative F, CBNG operators and 

subcontractors may need to drive across the Northern 

Cheyenne Reservation to reach some well sites in the 

northern part of the Planning Area (Rosebud County). 

Although the number of wells to be developed north of 

the Northern Cheyenne Reservation is relatively small, 

limited traffic, noise, safety and road maintenance 

impacts could occur on the reservation. The Northern 

Cheyenne are concerned that this would increase tribal 

member contact with outsiders, increasing the negative 

effects of social change described above. However, 

there is little reason for CBNG workers to stop on the 

reservation, as few services are offered on the 

reservation routes that would be used. Interaction with 
CHAPTER 4

Social and Economic Values

4-206

commuting workers would be of short duration and 

sporadic. 

Conclusions

Generally, the social and economic impacts resulting 

from Alternative G would be less than the other 

alternatives because of the greatly reduced number of 

federal wells that would be drilled. Also, a “boom and 

bust” cycle would be less likely as compared to the 

other alternatives, since CBNG development would be 

relatively steady over the phased development period, 

provided that development continues and the demand 

for natural gas remains.

Cumulative water resource impacts from Alternative G 

would be similar in nature to those expected from 

Alternative F. However, the magnitude of impacts 

would be less than Alternative F, as well as all the 

other development alternatives, due to the lower 

number of federal wells developed. 

Alternative H—Preferred Alternative - 

Multiple Screens

Under this Alternative, impacts would be similar to 

Alternative F. Alternative H manages the pace (rate) 

and place (geography) of federal CBNG development 

through protection measures applied to crucial habitat 

areas and limits to the discharge of untreated produced 

water from federal CBNG wells and emissions from 

sources associated with federal CBNG wells. More 

federal APDs could be approved annually and 

geographically than under Alternatives F and G to the 

extent that full field development could eventually 

occur under Alternative H as long as other resources 

are protected. Monitoring data would be required to 

help BLM determine which (where and when) federal 

APDs could be approved. These limits and thresholds 

(see Wildlife Appendix and Hydrology section) would 

serve to level the cumulative impacts over time. The 

production of CBNG would continue for a longer 

overall period of time compared to Alternative E 

because fewer number of federal CBNG wells may be 

drilled each year.

With these screens, the overall rate of well 

development would likely be about the same as 

Alternative F and slower than for Alternatives B 

through E, especially in those areas where the greatest 

level of drilling would occur, such as the Upper 

Tongue, Lower Tongue and Middle Powder 

watersheds. If no development occurs in the screen 

areas as a result of monitoring data, socioeconomic 

impacts including jobs and revenues could be reduced 

by as much as 12.8 percent. However, if monitoring 

data allows for the full field development of the screen 

areas, jobs and revenues could reach the levels 

predicted under the full field development alternative.

Employment and Unemployment

The development of wells for Alternative H is 

expected to follow the same pattern as Alternative F; 

therefore, employment for this alternative would be 

similar to Alternative F. Employment for Alternative F 

is shown in Table 4-61. Like Alternative F, Alternative 

H employment is expected to be lower than 

Alternatives B through E, but higher than Alternatives 

A and G. As for Alternative F, employment for 

Alternative H may be slightly higher than shown in 

Table 4-61, since a small number of additional jobs 

would be created to manage produced water from the 

federal CBNG wells. While the types of jobs generated 

under this alternative would be similar to those 

generated under the other development alternatives, the 

number of jobs and rate of jobs created per year are 

predicted to vary from the other alternatives. The 

number of wells drilled per year under Alternative H 

would be limited by the application of the four 

resource screens and watershed-level analysis, rather 

than a specific annual numerical limit on number of 

approved APDs. Therefore the number of wells 

developed each year could vary somewhat from what 

is predicted under Alternative F. 

The numbers of jobs presented in Table 4-61 have 

been calculated on an annual basis. In year one of the 

development period, 217 new jobs are expected to be 

created to implement approved APDs. In year two, 354 

jobs would be required; however, 217 of these jobs 

would likely be filled by the workers employed in year 

one. Consequently, the maximum number of workers 

needed in any one year would gradually increase over 

the development period from 217 to a peak of 1,039 in 

year 20, then gradually decrease as wells are 

abandoned.

Over the 23-year development period, there would be 

an annual average of 774 jobs created. This breaks out 

to an annual average of 243 initial development jobs, 

523 production jobs and 8 well abandonment jobs 

created. Additional abandonment jobs would be 

created after the development period. Like Alternative 

F, the total number of jobs created during the 23-year 

phased development period under Alternative H would 

be 14,707, as compared to 17,013 jobs during the 20-

year development period for Alternatives B through E.

The effect of Alternative H on current unemployment

rates in the area could be less than for Alternatives B 

through E. There is a potential for some residents in 

the Planning Area to obtain these new jobs if they have 

the appropriate skills, which would directly reduce 

unemployment, but most of the jobs created would 
CHAPTER 4

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likely be filled by CBNG workers living in Wyoming. 

Since most jobs created would go to Wyoming 

residents, most of the indirect effects of this new 

employment (wages spent on support services) would

also occur in Wyoming. 

Demographics

Employees working in the CBNG industry in the 

Montana portion of the Powder River Basin would 

likely commute from Wyoming. Most of the existing 

CBNG operations in Montana are located near Decker, 

Montana, with Sheridan, Wyoming (located 

approximately 20 miles away), the closest community 

with a population large enough to support CBNG 

operations. In addition, much of the proposed drilling 

in Montana would occur in four watersheds: Middle 

Powder River, Lower Powder River, Upper Tongue 

River and Lower Tongue River. These areas are 

located in the general vicinity of the towns listed 

above. 

New temporary jobs related to CBNG could be created 

by drilling and construction activities, or the 

application of technology that requires additional 

employees, while new permanent jobs could be created 

to oversee additional production wells and facilities. 

The available jobs range from laborers and other field 

positions to technical/professional positions such as 

geologists and engineers and other office staff 

positions. Additional support jobs include surveyors 

and research scientists. 

Most of the subcontracting companies used by CBNG 

companies operating in Montana are based in 

Wyoming. A small number of subcontracting 

companies and individual workers are from Montana. 

Job opportunities related to CBNG are advertised in 

both the Wyoming and Montana state job databases. 

Social Organization

Housing Units and Vacancy

Effects on housing would be similar to Alternative F. 

Most employees would commute from Wyoming, thus 

there would be little additional demand for housing in 

the Planning Area due to implementation of this 

alternative.

Public Services and Utilities

Similarly, this alternative would have little effect on 

public services and utilities since most of the workers 

would be living in Wyoming rather than the Planning 

Area. The highway connecting Sheridan to Decker 

would receive the most vehicle traffic related to CBNG 

operations in Montana. The communities of Sheridan, 

Gillette and Buffalo, Wyoming, would most likely be 

affected by additional employees needed to support 

CBNG operations in the area of Montana with the 

greatest potential for CBNG development. These 

communities, especially Sheridan, would continue to 

be called upon to provide public services, emergency 

services and support services for employees and their 

families. 

Cumulative impacts to Wyoming communities are 

discussed in the Impacts from Management Common 

to All Alternatives section. 

Attitudes, Beliefs, Lifestyles and Values

General impacts on population subgroups such as 

farmers, ranchers, small town residents, Native 

Americans and retirees, would be similar to 

Alternative F. Effects could include conflict with the 

attitudes, beliefs, lifestyles and values of many 

individuals. Drilling, testing and operation of CBNG 

wells would result in increased traffic from trucks and 

other vehicles; noise from traffic and the operation of 

generators and drilling and other equipment; visual 

resource impacts from the construction of the wells 

themselves, as well as power lines and related 

electrical infrastructure; and psychological stress 

associated with unwanted change, division in the 

community, or other impacts. The population 

subgroups would be affected to the degree to which 

their lifestyles and values are inconsistent with such 

impacts.

The majority of individuals in the Planning Area are 

understood to have traditional rural lifestyles in which 

the relatively quiet and pristine surroundings are an 

important value. They could find CBNG development 

inconsistent with the desired balance between 

environmental stewardship and economic development 

expressed in many of the scoping comments and 

newspaper reports. This would be particularly true for 

Big Horn, Powder River and Rosebud counties where 

the majority of the wells would be developed. Largescale CBNG development could be viewed as part of a 

gradual transition away from traditional rural and 

agricultural lifestyles. Some people in the area who are 

more interested in the potential economic benefits of 

CBNG development would likely perceive or 

experience fewer impacts with respect to lifestyles and 

values.

CBNG development is likely to conflict to some 

degree with traditional Native American values which 

emphasize preservation of cultural heritage and a 

reverence for the natural environment. Native 

American groups could be affected by increases in 

noise, impacts on visual resources and plant 

populations, etc., in particular as these affect locations 
CHAPTER 4

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and resources used for spiritual or religious purposes. 

It is assumed that no CBNG wells would be developed 

on the Native American reservations initially and

therefore impacts would be more likely to affect those 

individuals living off the reservations or whose 

activities are conducted off the reservations. Native 

American development is considered as part of the 

cumulative effects impact potential. It is likely that a 

smaller number of Native Americans who are 

interested in the development of energy resources 

would perceive or experience fewer harmful impacts 

from CBNG development.

Impacts on recreation areas would include the loss of 

land for recreation purposes and the disruption to 

recreation activities. Each well would present its own 

set of unique circumstances that would require

mitigation to minimize impacts. Exploratory activities, 

such as drilling and testing, would temporarily displace 

game species locally. Less recreation area would likely 

be disturbed compared to Alternatives B through E 

because the level of federal well development would 

likely be lower in each watershed and habitat 

disturbance would be limited. 

As for Alternative F, the use of watershed-level analysis, 

water management plans and water balance projections 

as part of PODs would reduce the water quality impacts 

expected from surface discharge of produced water. By 

use of watershed-level management of surface 

discharged water (i.e., 10 percent of 7Q10), impacts to 

surface water would be less than Alternative C and 

likely less than Alternative E.

The rate of development may not be as even as 

Alternative F if the screens allow more development.

This may concentrate the effect of development in 

earlier years more than Alternative F, but likely still 

less than Alternatives B through E. Residents in the 

areas of CBNG development would still be impacted 

by any activities approved by the State. 

Personal Income

Estimated CBNG wages for Alternative H would be 

about the same as shown in Table 4-61 for Alternative 

F. These wages would add to the total personal income 

mainly in the localities where employees reside 

(Wyoming). Wages would be produced from the 

development, production and abandonment phases. 

The estimated total wages over the phased 

development period would be $629,454,459. Annual 

wages are estimated to be $27,367,585, but would 

range from $6.6 million in year 1 to $38.2 million in 

year 21. 

Income would also be generated by those who own the 

land or the mineral rights as described for Alternative 

A. Purchases made with CBNG income would produce 

some additional indirect income in the region as 

earnings circulate through the economy. Most of this 

would likely be spent in Wyoming, where workers are 

expected to reside. 

Government Revenues

Oil and Gas Income

Assuming that of the 18,225 wells drilled, approximately 

10 percent would be dry holes, then approximately 

16,403 wells would be left to generate production 

income. Production income under Alternative H would 

be expected to be about the same as Alternative F and 

lower than Alternatives B through E.

Using the same production income as Alternative B, 

gross production income per year of operation would 

be approximately $182,500 per well. The number of 

producing wells would range from 546 in year 1 to 

15,052 in year 20 (see Table 4-61). It follows that 

estimated annual gross income would range from $100 

million (year 1) to $2.7 billion (year 20). Like 

Alternative F, royalty income of 12.5 percent would 

range from $12 million (year 1) to $343 million (year 

20), as compared to $12 to $322 million for 

Alternatives B through E. There is no maximum 

annual number of producing wells for this alternative, 

although the screens would limit well development. 

Distribution of production and royalty income to BLM, 

state (private) minerals and private minerals and 

income from rents and leases for oil and gas 

development would be similar to Alternatives B and F. 

Generally, new state revenues from CBNG would be 

substantial. This source of state revenue could be more 

evenly spread over the development period like 

Alternative F. If this occurs, this would be a more 

constant source of income for the state, rather than a 

large infusion of revenue early in the program (years 1-

5) that would dwindle over time. 

Similar to Alternative B and F, government revenue 

from oil and gas would be reduced by costs for 

monitoring and regulating CBNG activity and water 

treatment. However, these costs are relatively small as 

compared to the generated revenue.

Under Alternative H, the Crow and Northern 

Cheyenne reservations would be protected from 

drawdown of coal seam aquifers and drainage of tribal 

CBNG and groundwater resources by the 

establishment of a 5-mile buffer zone around the 

borders of the reservations. If the development of 

federal minerals within the 5-mile buffer zone is 

delayed or restricted while development on state and 

private leases continue, then the situation develops 
CHAPTER 4

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where there would be the increased potential for 

drainage of federal minerals. Within the 5-mile buffer 

zone of reservation boundaries, BLM managed 

minerals represent 24 percent (127,165 acres) of total 

mineral ownership (463,118 acres) within the Billings 

RMP Area and 64 percent (250,565 acres) of total 

mineral ownership (355,307 acres) within the Powder 

River RMP Area. These federal minerals could contain 

as much as 1.4 to 1.6 TCF of gas that may be lost to 

the federal, state and county governments [(127,165 

acres + 250,565 acres)/1 well site per 80 acres * 0.3 to 

0.34 BCF per well site]. The loss of royalties to the 

Federal government would be approximately $1.2 

billion at current gas prices.

These statistics do not take into account the federal 

minerals administered by the Custer National Forest, 

Ashland Ranger District. 

Taxes

Income Taxes

Income taxes generated from CBNG development

would be similar to Alternative F and they would 

likely be paid in Wyoming, since most workers are 

expected to come from that state. 

Property Taxes

Like the other alternatives, property taxes would 

accrue to counties roughly in proportion to the number 

of new wells. Big Horn, Powder River and Rosebud 

counties would have the vast majority of new wells; 

therefore, they would likely experience the greatest 

increases in assessed values and the greatest increase 

in new county property tax revenues. These new 

revenues could help improve schools, roads, 

community services and other county assets, after 

accounting for any new costs associated with CBNG. 

There could be some slight difference between the 

alternatives related to which counties would accrue 

these taxes. This may be caused by limiting CBNG 

development by watersheds instead of other 

jurisdictional boundaries. 

Natural Resources Taxes

Like the other alternatives, the products of natural 

resource extraction in Montana, including natural gas, 

are subject to state natural resource taxes, including 

local government severance taxes. Any new production 

of natural gas would be subject to such taxes.

Severance taxes are distributed to a variety of state and 

local funds and would contribute positively to the state 

and local economies.

Other Taxes

The local and state economies would benefit from 

sales of goods and services by local businesses to oil 

and gas operators associated with the project.

However, local sales of goods and services associated 

with CBNG development would not generate increases 

in tax revenues because there is no sales tax in 

Montana. In addition, most of the purchases associated 

with CBNG development would likely be made in 

Wyoming.

Water Resource Values

Due to the water screen, Alternative H would have 

impacts on water resources and water resource values 

similar to or less than Alternatives C through F. This 

alternative would allow limited discharge of untreated 

water under certain conditions. The volume of 

discharge from federal wells would be based on 10 

percent of the 7Q10 flow calculated from all CBNG 

wells at the downstream end of the watershed. The 10 

percent limit would not apply if surface water 

monitoring is being conducted above and below the 

proposed outfalls. If surface water monitoring indicates 

a water quality threshold would be exceeded, no 

further untreated discharge would be allowed from 

federal wells upstream from the station. Previously 

approved water management plans may be modified or 

rescinded if monitoring indicates unacceptable impacts 

are occurring. Water quality thresholds and the surface 

water monitoring requirements are detailed in the 

Hydrology Appendix. Water produced by federal wells 

may be treated, used for beneficial uses, or re-injected 

into the ground if the 10 percent allowable discharge 

has already been exceeded. 

Discharge of produced water into State waters would 

be allowed only under an approved State permit which 

would protect existing uses. Produced water put to 

beneficial use would provide an economic benefit to 

affected water users.

As for Alternatives B though F, localized groundwater 

drawdown would occur over time. The risk of such 

drawdown would likely be greater than Alternative B, 

since reinjection of all produced water is not required 

under this alternative. However, water well mitigation

agreements would address the potential reduction or 

loss of water resources and provide for prompt 

supplementation or replacement of water from any 

nearby natural spring or water well adversely affected 

by a CBNG well. 

Crow Reservation

Alternative H would result in similar social and 

economic impacts on the Crow Reservation as 
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Alternative F. Similar to other Montana residents, 

unless Crow tribal members are already working in the 

CBNG industry out of Wyoming, it is unlikely that 

tribal members would fill the jobs created by 

Alternative H. Alternative H requires monitoring of 

federal CBNG development within 5 miles of the 

Crow Reservation. Site-specific groundwater and air 

quality analysis and mitigation measures would be 

required and implemented through the operator’s Plan 

of Development. Indian Trust Assets (ITAs) would be 

protected from federal CBNG wells located within 5 

miles of the Crow Reservation and if analysis showed 

that ITAs would be adversely affected, then BLM 

would consult with the tribe and determine appropriate 

mitigation measures which may include not approving 

the APD. BLM would require groundwater monitoring 

wells and air monitoring between the federal well field 

development area and the reservation. If this 

monitoring indicates ITAs are not being protected, 

then the wells would be shut in.

CBNG workers needing to travel from Sheridan or 

Gillette to the potential CBNG sites in the western part 

of the Planning Area would likely avoid traveling 

across the Crow Reservation by driving from Sheridan 

to Lovell, Wyoming or travel north from Powell, 

Wyoming or travel south from Billings, Montana. 

However, if CBNG development occurs on the Crow 

Reservation, workers from Wyoming would enter the 

Reservation.

Northern Cheyenne Reservation

Alternative H would likely result in similar impacts on 

the Northern Cheyenne Reservation related to 

population, employment and social conditions as 

identified under Alternative F. Like other Montana 

residents, unless Northern Cheyenne tribal members 

are already working in the CBNG industry out of 

Wyoming, it is unlikely that tribal members would fill 

the jobs created by Alternative F. Some off-site 

members may be encouraged by perceived job 

opportunities to return to the Reservation, which could 

increase demand for public services. Some tribe 

members are concerned that increased stress caused by 

social changes due to CBNG development may also 

increase the likelihood of alcoholism, drug abuse and

family violence.

Alternative H includes a Native American Concerns 

screen that would protect groundwater and air 

resources and would require monitoring of federal 

CBNG development within 5 miles of the Northern 

Cheyenne Reservation. These requirements would 

protect ITAs and include site-specific groundwater and 

air quality analysis. This analysis would be included in 

the operator’s Plan of Development. Indian Trust 

Assets (ITAs) would be protected from federal CBNG 

wells located within 5 miles of the Northern Cheyenne 

Reservation and if analysis showed that ITAs would be 

adversely affected, then BLM would consult with the 

tribe and determine appropriate mitigation measures 

which may include not approving the APD. BLM 

would require groundwater and air monitoring between 

the federal well field development area and the 

Reservation. If this monitoring indicates ITAs are not 

being protected, then the wells would be shut in. 

Like the other alternatives, CBNG operators and 

subcontractors under Alternative H may need to drive 

across the Northern Cheyenne Reservation in order to 

reach some well sites in the northern part of the 

Planning Area (Rosebud County). Although the 

number of wells to be developed north of the Northern 

Cheyenne Reservation is relatively small, limited

traffic, noise, safety and road maintenance impacts 

could occur on the reservation. The Northern

Cheyenne are concerned that this would increase tribal 

member contact with outsiders, increasing the negative 

effects of social change described above. However,

there is little reason for CBNG workers to stop on the 

reservation, as few services are offered on the 

reservation routes that would be used. Interaction with 

commuting workers would be of short duration and 

sporadic.

Conclusions

Social and economic impacts, such as employment, 

income, demographic migration, taxes, changes in 

lifestyle and social conditions would likely be similar 

to Alternative F. Like the other alternatives, new jobs 

would likely be filled by CBNG workers from 

Wyoming. Depending on limitations set by the four 

resource screens and watershed-level analysis, CBNG 

development could be relatively steady over the 

development period, provided development continues 

and the demand for natural gas remains. Under 

Alternatives B through E, CBNG development would 

increase rapidly, peaking over a 5-year period and then 

decrease over the remainder of the development 

period.

The social and economic impacts are likely to vary 

slightly from the other alternatives because 

development would occur based on watersheds, which 

may further spread CBNG development outside the 

three main counties most affected under Alternatives B 

through E (Big Horn, Powder River and Rosebud). 

This may reduce the overall impacts on social 

conditions and lifestyles. 

The cumulative reduction in federal royalties due to 

the 5-mile buffer development delay/restriction around 
CHAPTER 4

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reservations would result in a $1.2 billion loss to the 

federal government at current gas prices.

Cumulative water resource impacts from Alternative H 

would be less than Alternative C and E and more than 

Alternative B. 

Environmental Justice

Environmental Justice

Executive Order 12898 requires the non-discriminatory 

treatment of minority and low-income populations for projects 

under the jurisdiction of a federal agency 

Alternative A

No Action (Existing CBNG Management)

• Few adverse impacts with the exception of the 

undetermined Wyoming discharge influence. 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• The influence of Wyoming’s discharge on Montana rivers 

would constitute a potential environmental justice issue if 

unresolved. 

Alternative C

Emphasize CBNG Development 

• Same as Alternative B except for adverse environmental 

effects would be expected from downstream water quality 

changes resulting in limitations to subsistence living 

styles. These limitations would fall disproportionately on 

minority or low-income populations from this alternative. 

Wyoming Discharge issues same as Alternative B.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• No adverse human health or environmental effects would 

be expected to fall disproportionately on minority or lowincome populations from this alternative. Wyoming 

Discharge issues same as Alternative B.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• No adverse human health or environmental effects would 

be expected to fall disproportionately on minority or lowincome populations from this alternative.

Alternative F

Phased Development Multiple Screens (High Range)

• With mitigation, no adverse human health or 

environmental effects would be expected to fall 

disproportionately on minority or low-income populations 

from this alternative. Wyoming Discharge issues same as 

Alternative E. 

• Project Plan and watershed-level analysis requirements 

would help to mitigate potential impacts.

• Project Plan consultation with tribes and on-going 

monitoring for developments within 5 miles of a 

Reservation would help to protect Indian Trust Assets.

Alternative G 

Phased Development Multiple Screens (Low Range)

• Impacts would be less than other development alternatives 

due to fewer federal wells being developed.

• With mitigation, no adverse human health or 

environmental effects would be expected to fall 

disproportionately on minority or low-income populations 

from this alternative. Wyoming Discharge issues same as 

Alternative B.

• Project Plan and watershed-level analysis requirements 

would help to mitigate potential impacts.

• Project Plan consultation with tribes and on-going 

monitoring for developments within 5 miles of a 

Reservation would help to protect Indian Trust Assets.

Alternative H 

Preferred Alternative - Multiple Screens

• Impacts would be similar to Alternative F due to similar 

number of wells developed. With mitigation, no adverse 

human health or environmental effects would be expected 

to fall disproportionately on minority or low-income 

populations from this alternative. Wyoming Discharge 

issues same as Alternative B.

• Project Plan, resource screens and watershed-level 

analysis requirements would help to mitigate potential 

impacts.

• Project Plan consultation with tribes and on-going 

monitoring for developments within 5 miles of a 

Reservation would help to protect Indian Trust Assets.

Assumptions

The purpose of this analysis is to report whether high 

and adverse human health or environmental effects of 

the proposed alternatives are likely to fall 

disproportionately on minority or low-income 

populations. This analysis focuses on the populations 

that are located within the areas potentially affected by 

the alternatives. It examines where expected high and 

adverse impacts, if any, fall relative to minority and 

low-income populations. In order to make a finding 

that a proposed project is inconsistent with the 

Environmental Justice policy established in Executive 

Order (EO) 12898 and described in Section 4.10.1.7, 

two situations must occur at the same time: 1) there

must be a minority or low-income population; and 

2) that population must receive a disproportionately 

high and adverse environmental or human health 

impact.

Two options are considered depending on what the 

impacts are:

• If adverse impacts are identified in the resource 

analyses, the individual occurrence potential is 
CHAPTER 4

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4-212

analyzed for disproportionate effects on minority 

and/or low-income populations.

• If no adverse impacts are identified in the resource 

analyses, then no environmental justice issues 

would be expected as a result of the alternative. 

Therefore, it can be concluded that no adverse 

human health or environmental effects would fall 

disproportionately on minority or low-income 

populations. Consequently, none of the impacts of 

the alternative can be described as having a high 

and adverse impact in the context of EO 12898. 

The proposed alternatives are therefore consistent 

with the policy established in EO 12898.

Scoping comments indicated that analysis from the 

Economic, Social and Cultural Supplement to the 

Powder River I Regional EIS (BLM 1989) was 

relevant to the analysis of impacts to the reservations. 

The analysis found that although coal development 

activities would be off-reservation, economic, social

and cultural impacts could occur on the reservation.

Economic and social impacts would occur primarily 

due to tribal members moving back to the reservation 

to seek employment and people living off-reservation 

coming to the reservation to seek recreation and 

services. Impacts identified by the supplement 

included increased demand for services such as 

housing, water, health services, education and

emergency services, as well as increased stress 

associated with social change potentially leading to 

increases in alcoholism, drug abuse, family violence, 

crime and feelings of deprivation because the 

reservation would receive negative impacts, but few 

benefits, from regional coal development. 

This type of effect is not expected to occur because, 

unlike the development of coal, which employs many 

Montana workers, CBNG development would not 

provide many employment opportunities for people in 

Montana. Most of the jobs would be filled by workers 

currently employed by the CBNG industry based in 

Wyoming. These workers would have little to no affect 

on the reservation because they will not be driving 

across it on a routine basis. Similar to other Montana 

residents, unless tribal members are already working in 

the CBNG industry out of Wyoming, it is unlikely that 

tribal members would fill the jobs created by the 

alternatives. In addition, the area of high interest for 

CBNG is located further away from the Northern 

Cheyenne Reservation than some of the possible coal 

mines projected in the 1989 Coal SEIS. 

In addition to the concern listed above, the increased 

need for coordination and interaction with local, state

and federal governments is a concern for tribal 

resources. See the Indian Trust and Native American 

Concerns section in this chapter for further discussion 

of cultural impacts.

Impacts from Management Common to All 

Alternatives

Social and Economics Values

Although none of the alternatives propose CBNG 

development on the reservations, the Crow and 

Northern Cheyenne tribes could be affected by

increases in noise, impacts on visual resources and 

plant populations, etc., in particular, as these affect 

locations and resources used for spiritual or religious 

purposes.

It is expected that development will occur first within 

the southern portion of the Planning Area; this is where 

CBNG development is currently occurring within the 

CX Ranch Field. CBNG workers that come from 

Sheridan or Gillette in Wyoming to develop wells 

within the southern portion of the Planning Area will 

not cross the Northern Cheyenne or Crow Reservations 

on their journey to work. 

When the wells to the north are developed, CBNG 

workers may need to drive across the Northern 

Cheyenne Reservation to reach some of those sites. 

Although the number of wells to be developed north of 

the Northern Cheyenne Reservation is relatively small, 

limited traffic, noise, safety and road maintenance 

impacts on the reservation could occur. The Northern 

Cheyenne are concerned that this would increase tribal 

member contact with outsiders, increasing the negative 

effects of social change described above. However, as 

with any of the alternatives, there would be little 

reason for CBNG workers to stop on the reservation, 

as few services are offered on the reservation routes 

that would be used. Interaction with commuting 

workers is not expected

CBNG workers needing to travel from Sheridan or 

Gillette to the relatively small number of potential 

CBNG sites in the western part of the Planning Area

would likely drive across the Crow Reservation on 

I-90. Because this is a heavily traveled interstate, the 

incremental increase in traffic would not adversely 

affect the Crow Reservation. 

There is a small Amish community in Rosebud County

that may be a low-income population. Well 

development under any of the alternatives would 

adversely affect this community if well sites are 

located nearby. However, with the measures to 

mitigate effects on groundwater and other measures to 

reduce effects, CBNG development is not expected to 

have disproportionately high and adverse effects on 

this community.
CHAPTER 4

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Under management common to all alternatives, the EO 

and BLM policy guidance would continue to provide 

for minority participation in future BLM management 

decisions. 

Impacts From Management Specific to 

Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

Areas that require further analysis for disproportionate 

effects to minorities or low-income populations

include water quality (potential impact of CBNGproduced waters being discharged into the Little 

Bighorn River and the Tongue River Reservoir from 

Wyoming CBNG activities) and social and economic 

effects. See discussions below.

Water Quality

Crow Reservation

The Little Bighorn River, which originates in 

Wyoming and flows onto the Crow Reservation, could 

experience impacts to its water quality. The changes in 

water quality would be dependent upon the terms of 

the Final Water Quality Agreement signed between 

Montana and Wyoming. The current interim agreement 

does not address the Little Bighorn watershed. Impacts 

could range from a negligible effect to a modest 

increase in SAR, TDS, EC and bicarbonate. If the 

agreement allows for some CBNG-produced water to 

be discharged into the Little Bighorn River, the 

resulting downstream water would increase SAR, EC, 

TDS and bicarbonate, thus the tribe’s beneficial use of 

that water may be diminished, as well as the tribe’s 

ability to market their water as a commodity. No health 

effects are foreseen from the change in water quality or 

the consumption of downstream fish present in the 

Little Bighorn River. 

Northern Cheyenne Reservation

Impacts to the Northern Cheyenne’s Water Right in the 

Tongue River Reservoir would be the result of 

Wyoming allowing CBNG-produced waters to be 

discharged into the Tongue River, altering the water 

quality of the reservoir. The range of water quality 

changes would be dependent upon the Final Water 

Quality Agreement between Montana and Wyoming. 

Current policy in Wyoming is that there would be no 

discharge of CBNG-produced water into the Tongue 

River. The scenarios for possible impact ranges are 

described in detail in the Hydrological Resources 

section of this chapter. Worth mentioning though, is 

that even a slight change in water quality to the 

reservoir could impact the Northern Cheyenne’s ability 

to market their water as a commodity and reduce their 

own beneficial uses.

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All Alternatives

could occur under Alternative A. However, there 

would be fewer CBNG workers driving across the 

reservation than for Alternatives B thru H; thus, the 

potential traffic, noise, safety, road maintenance and

worker interaction impacts on the Northern Cheyenne 

Reservation would be less.

Conclusion

The potential impacts to the surface water concerns of 

both tribes would be somewhat alleviated by their 

participation in the state-to-state discussions regarding 

the Water Quality Agreement. If either tribe were to 

obtain self-governance over their water quality, they 

could act with the authority of a state and set their own 

water quality or non-degradation standards and 

negotiate with Wyoming for an altered agreement 

more in line with their specific needs and concerns. 

Currently, the Northern Cheyenne are working with 

the EPA to adopt draft water quality standards and 

obtain primacy for their surface water. The lower 

number of jobs associated with this alternative would 

lead to fewer people driving across the reservations. 

Alternative B—Emphasize Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

A review of the resource analyses conducted for 

Alternative B identifies the following impacts that 

warrant further review for disproportionate effects on 

minority or low-income populations. The impacts 

included in this evaluation are the drawdown of 

groundwater; air quality changes; changes to 

vegetation and soils; and social and economic values. 

Groundwater Drawdown

CBNG production in Montana would result in the 

depletion of an estimated 23 percent (ALL 2001b) of 

the groundwater resources in the productive coal seams 

beneath Montana’s Powder River Basin. This 

drawdown would be basinwide and correspond to the 

geographical distribution of production wells. The 

occurrence potential is not localized and would not 

impact segregated portions of the population; the 

impact would be felt evenly across the region. 

Furthermore, the drawdown has the potential to reduce 

surface water flows in some drainages depending on 

specific site conditions. The availability of 

groundwater is important, as many rural families 
CHAPTER 4

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depend on the supply of groundwater for their 

household and ranch/agricultural (irrigation) 

applications.

Air Quality Changes

CBNG development in the Powder River Basin would 

necessitate the construction of minor emission sources 

spread out over a very large area. The air quality 

modeling shows potential air quality impacts at 

downwind mandatory Federal PSD Class I areas and

that other “sensitive receptors” would exceed the PSD 

Class I NO2 increment; cause nitrate and sulfate 

atmospheric deposition (and their related impacts) in 

sensitive lakes; and cause perceptible visibility impacts 

(regional haze). Additionally, there is the potential for 

the NAAQS to be exceeded for NOx in the Spring 

Creek Coal Mine area. However, it should be noted 

that these findings are representative of the maximum 

potential air quality impacts.

Generally, the potential changes in air quality from 

development would be within acceptable limits, 

widespread and distributed across the region. The 

impacts associated with the dispersion of air pollutants 

across the region would not be disproportionately 

distributed upon any minority or low-income groups.

Crow Reservation

Under this alternative, a 2-mile buffer zone would be 

enforced on federal mineral development around the 

reservation to restrict development of minerals 

adjacent to these boundaries. This buffer zone would 

delay some of the groundwater drawdown impact 

associated with federal pumping but would not prevent 

state and private mineral estates from being developed 

adjacent to the reservation. Therefore, drawdown could 

affect Indian populations within the Crow Reservation

adjacent to off-reservation development.

The Crow tribal government derives some of its 

income from operator lease fees: ranchers and 

irrigators operating both on private and reservation

lands. If these operators were to experience a reduction 

in available groundwater that impacted their operations 

and the Crow Tribe subsequently had to reduce their 

fees, the tribe would lose a portion of their income. 

Trust agencies might be needed to resolve conflicts. 

The form of resolution most desirable would be the 

replacement of water resources and the according 

adjustment in fees. If the replacement of water 

resources could not be achieved because of sitespecific conditions or other variables, the loss in 

potential income generation from reduced fees and 

limited new private opportunities would have to be 

made up for or this could be an environmental justice

issue.

Northern Cheyenne Reservation 

The Northern Cheyenne Tribe would experience 

similar groundwater drawdown and potential operator 

lease private issues as discussed under the Crow 

Reservation section above.

As described under the above Air Quality Changes 

section, the air quality modeling shows potential air 

quality impacts at downwind mandatory Federal PSD 

Class I areas and the Northern Cheyenne’s PSD Class I 

area, as well as causing a small increase in perceptible 

visibility impacts (regional haze). However, these 

findings are representative of the maximum potential 

air quality impacts.

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All Alternatives

could occur under Alternative B. There would be more 

CBNG workers driving across the reservations to reach 

well sites due to the larger number of wells to be 

developed; thus, the traffic, noise, safety, road 

maintenance and worker interaction impacts on the 

Northern Cheyenne Reservation would be more than 

Alternative A, but are not expected to be substantial, as 

described in Impacts from Management Common to All 

Alternatives. To reduce effects of speeding vehicles, 

operators of federal leases would be required to post 

and enforce speed limits on their employees, or 

employees of their contractors.

Conclusions

If the Northern Cheyenne and Crow tribes elected to 

develop their CBNG resources the federal buffer zone 

would not be used to limit the effect on the reservation. 

An additional percentage of drawdown would be 

experienced across the basin watersheds from the 

Northern Cheyenne and Crow tribal developments (see 

Hydrological Resources section for details). If the 

tribe’s CBNG resources were drilled to the degree 

estimated in the RFFA (4,000 wells for each 

reservation), the depletion of the coal seam aquifer 

groundwater resource could increase across the region 

and cause a hardship on numerous low-income and 

minority populations, which are prevalent throughout 

the area. However, water well and spring mitigation

agreements required by the MBOGC, BLM and

TLMD would provide alternate sources of water due to 

groundwater lost to the drawdown of resources within 

the coal seam aquifers. Drawdown in non-producing 

coal seams aquifers is not anticipated. Replacement 

may not be possible in some areas with concentrated 

CBNG production. This represents a possible 

environmental justice issue if the non-replacement 
CHAPTER 4

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areas are adjacent to reservation boundaries and no 

suitable water is available for mitigation.

No adverse human health impacts are foreseen from 

these environmental changes. The influence of 

Wyoming’s discharge on Montana rivers would 

constitute a potential environmental justice issue if 

unresolved. Social and economic effects on the Crow 

and Northern Cheyenne tribes under this alternative 

would be more than Alternative A, but are not 

expected to be substantial.

Alternative C—Emphasize CBNG 

Development

The resource analyses performed for Alternative C 

indicate that groundwater drawdown, social and 

economic values and changes to the surface water 

quality and the subsequent impacts on vegetation, 

wildlife and aquatic resources would have effects that 

warrant further review for disproportionate effects on 

minority or low-income populations.

Groundwater Drawdown

The drawdown of groundwater within the Powder 

River Basin would have greater effects than described 

under Alternative B. Without the federal development 

buffer zone around reservations, drawdown effects 

could be amplified and appear sooner on reservation 

properties than under Alternative B.

Surface Water Quality

Under Alternative C, the quality and quantity of 

surface waters in the Powder River Basin could be 

altered depending on the outcome of the statewide 

water quality standards. The MDEQ is in the process 

of setting statewide water quality standards that would 

likely include the framework for managing surface 

discharge of CBNG-produced water throughout the 

state. The watersheds would most likely experience 

increases in SAR values, sedimentation, TDS and a 

marginal increase in base flow as described in the 

Hydrological Resources section of this chapter. Based 

on SAR values, the addition of untreated CBNGproduced waters with high SAR values under the least 

restrictive extreme criteria would not exceed an SAR 

value of 12. High-quality watersheds in the FSEIS

Planning Area would have adequate assimilative 

capacity to accept expected discharges from full-scale 

development of CBNG. All other watersheds should 

only experience a slight increase in SAR, which would 

remain below the suggested not to exceed a value of 

3 for some soils and possibly as high as 12 for others.

It is assumed that the sodium content of produced 

CBNG water is the target contaminant that determines 

the usefulness of the water for crop irrigation. 

Irrigation uses the majority of water resources in those 

watersheds thought to have the greatest potential for 

CBNG development. Sodium causes osmotic stress to 

plants and destroys the texture of clayey soils; these 

combined effects make sodium content and especially 

SAR, a point of emphasis when gauging impacts to 

water resources from CBNG water. Other parameters 

such as TDS, nitrogen and barium concentration may 

be locally important in determining restrictions to 

beneficial use. It is assumed that discharge to highquality watersheds would be limited during the 

irrigation season and managed on a flow-based 

discharge scenario. Under these circumstances, highquality watersheds in the FSEIS Planning Area would 

have sufficient capacity to meet the current irrigation 

needs. Flow-based discharge would however, require 

additional storage of produced water during the 

irrigation season for later discharge when stream flows 

are less sensitive to being impacted by produced water 

discharges.

The consequential downstream effects of increased 

SAR and base flow would result in the erosion of 

riparian areas along rivers, the reduction of both 

vegetation and wildlife habitat and the impairment of 

fish populations. These consequential effects are 

mentioned because of the large number of Native 

Americans who have a traditional reliance on the 

natural agriculture for sacred plants used in medicines 

and for their hunting and fishing way of life. If these 

combined water quality impacts are realized, there 

could be a disproportionate effect felt by the Native 

Americans as it reduces their ability to gather sacred 

plants and limit their hunting and fishing opportunities. 

A large percentage of the population in Big Horn 

(61 percent) and Rosebud (33 percent) counties are 

Native Americans and constitutes a sizeable minority 

population within the FSEIS Planning Area. 

Crow Reservation

Impacts on the Crow Reservation are expected to be 

similar to impacts projected for the FSEIS Planning 

Area. The reservation can expect impacts to Bighorn, 

Little Bighorn, Rosebud and Squirrel Creek 

watersheds, such as increased flow volume, changes to 

water quality parameters, including SAR, EC and

bicarbonate. The Crow Tribe could experience 

drawdown of groundwater in coal seam aquifers from

Wyoming and Montana CBNG production. The 

traditional pattern of natural resource consumption 

would be altered and therefore impacts to sacred plants 

and hunting and fishing are expected.
CHAPTER 4

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Northern Cheyenne

Impacts on the Northern Cheyenne Reservation are 

expected to be similar to impacts projected for the 

FSEIS Planning Area. The Northern Cheyenne 

Reservation could experience impacts to the Tongue 

River and Rosebud Creek in the form of increased flow 

volume and changes to water quality parameters, 

including SAR, EC and bicarbonate. The reservation 

could also experience drawdown of coal seam aquifers 

from CBNG production in the area surrounding the 

reservation. The traditional pattern of natural resource 

consumption would be altered and therefore impacts to 

sacred plants and hunting and fishing are expected.

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All 

Alternatives could occur under Alternative C. The 

number of CBNG workers driving across the 

reservations to reach well sites would be similar to 

Alternative B; thus, the traffic, noise, safety, road 

maintenance and worker interaction impacts on the 

Northern Cheyenne Reservation would be similar.

Conclusions

These surface water quality and quantity effects, when 

combined with the increases projected from similar 

current and planned CBNG development activities in 

Wyoming, would further increase the SAR value, base 

flow and other potential constituents of concern in the, 

Powder and Little Powder rivers. The combined 

decrease in water quality would necessitate the use of 

flow-based discharge to avoid limiting the resource for 

use as a source of irrigation. The resulting impacts may 

still impair tribal government leasing activities. This 

could create an environmental justice issue to tribes as 

described under Alternative B.

No adverse human health impacts are foreseen from 

these environmental changes. The influence of 

Wyoming’s discharge on Montana rivers would 

constitute a potential environmental justice issue if 

unresolved. It is concluded that adverse environmental 

effects could occur from downstream water quality 

changes, resulting in limitations to subsistence living 

styles. These limitations would fall disproportionately 

on minority or low-income populations from this 

alternative.

Social and economic effects on the Crow and Northern 

Cheyenne tribes under this alternative would be similar 

to Alternative B.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Air Quality, Surface Water Quality and

Groundwater Drawdown

A review of the resource analyses for Alternative D 

revealed that similar potential effects would be felt as 

described under Alternative B for groundwater 

drawdown and air quality changes and under 

Alternative C for surface water quality but at a reduced 

impact because of water treatment and discharge 

conveyance. The same trickle-down effects would be 

experienced under Alternative D as described in 

Alternative C but, again, at a reduced level because of 

water treatment.

Crow Reservation

Impacts on the Crow Reservation are expected to be 

similar to impacts described under Alternative C with 

the exception of Montana CBNG surface water quality 

impacts. Surface water impacts would be limited to 

changes due to increased quantity of surface discharge 

but treatment prior to discharge would reduce impacts 

to water quality compared to Alternative C. 

Groundwater impacts would be the same as 

Alternative B.

Northern Cheyenne

Impacts on the Northern Cheyenne Reservation would 

be similar to impacts described under Alternative C 

with the exception of Montana CBNG surface water 

quality impacts. Surface water impacts to the Tongue 

River and Rosebud Creek would result from increases 

in quantity of surface discharge but treatment prior to 

discharge could reduce impacts to water quality. 

Groundwater impacts would be the same as 

Alternative C.

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All 

Alternatives could occur under Alternative D. The 

number of CBNG workers driving across the 

reservations to reach CBNG sites would be similar to 

Alternatives B and C, thus the traffic, noise, safety, 

road maintenance and worker interaction impacts on 

the Northern Cheyenne Reservation would be similar. 

To reduce effects of speeding vehicles, operators of 

federal leases would be required to post and enforce 

speed limits on their employees, or employees of their 

contractors.
CHAPTER 4

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Conclusions

The surface water quantity effects, when combined 

with the increases projected from similar current and 

planned CBNG development activities in Wyoming, 

would be less than those described in Alternative C 

because of the treatment of discharge water. Water 

would be available for irrigators and tribal government 

leasing activities and would not be impaired. The 

drawdown of groundwater and subsequent availability 

would be as described in Alternative B. If the Northern 

Cheyenne and Crow Tribes elected to develop their 

CBNG resources, impacts would occur as described 

under Alternative B. 

Social and economic effects on the Crow and Northern 

Cheyenne Tribes under this alternative would be 

similar to Alternatives B and C.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Air Quality, Surface Water Quality and

Groundwater Drawdown

The impact analyses for Alternative E shows that 

impacts on surface water quality would be slightly 

altered; however, downstream uses would not be 

diminished nor would the State’s water quality 

standards be exceeded. Alternative E stresses the 

beneficial uses of produced water from CBNG wells 

and requires a Water Management Plan be developed 

that demonstrates how an operator can discharge 

without degrading the surface water quality before any 

discharge can occur. Similar potential effects would 

occur as described under Alternative B for 

groundwater drawdown and air quality changes. 

Crow Reservation

Impacts on the Crow Reservation are expected to be 

similar to impacts projected for the region under 

Alternative E with the exception of groundwater 

impacts. Operators are required to conduct site-specific 

hydrological studies prior to APD approval. If the sitespecific studies determine there would be an effect to 

Reservation groundwater, the operator must develop 

and apply measures to prevent the impact of 

groundwater withdrawal and monitor the effectiveness 

of such measures. These measures would be approved 

by BLM in consultation with the tribe. Furthermore, 

operators must modify federal CBNG production if 

production is resulting in an effect on groundwater or 

CBNG on the Reservation. BLM requirements could 

include reducing production rates, shutting in the well 

or wells, or providing compensation to the tribe. The 

operator must correct the impact of groundwater 

withdrawal prior to resuming full production.

For lands under the jurisdiction of the State, the 

operator would be required to follow recommendations 

in the Technical Advisory Committee’s guidance 

document for meeting the requirements of the 

MBOGC Order No. 99-99. The order requires an 

evaluation of pre-development groundwater 

conditions, plus monitoring and evaluations, including 

procedures for monitoring and reporting the effects of 

CBNG development on water users. Based on the 

implementation of these measures tribal groundwater 

resources would be protected and potential impacts 

eliminated. 

Northern Cheyenne

Impacts on the Northern Cheyenne Reservation are 

expected to be similar to impacts projected for the 

region under Alternative E with the exception of 

groundwater impacts. Operators are required to 

conduct site-specific hydrological studies prior to APD 

approval. If the site-specific studies determine there 

would be an effect to Reservation groundwater, the 

operator must develop and apply measures to prevent 

the impact of groundwater withdrawal and monitor the 

effectiveness of such measures. These measures would 

be approved by BLM in consultation with the tribe. 

Furthermore, operators must modify federal CBNG 

production if monitoring shows production is resulting 

in an effect to groundwater or CBNG on the 

Reservation. BLM requirements could include

reducing production rates, shutting in the well or wells, 

or providing compensation to the tribe. The operator 

must correct the impact of groundwater withdrawal 

prior to resuming full production.

For lands under the jurisdiction of the State, the 

operator would be required to follow recommendations 

in the TAC guidance document for meeting the

requirements of the MBOGC Order No. 99-99. The 

order requires an evaluation of pre-development 

groundwater conditions, plus monitoring and 

evaluations, including procedures for monitoring and 

reporting the effects of CBNG development on water 

users. Based on the implementation of these measures, 

tribal groundwater resources would be protected and 

potential impacts eliminated. 

Surface water impacts on the Tongue River and 

Rosebud Creek would also be reduced. The surface 

water quality in these two waterbodies would be 

slightly altered; however, downstream uses would not 

be diminished nor would the proposed Northern 

Cheyenne water quality standards be exceeded. 
CHAPTER 4

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4-218

With regards to air quality, operators would be 

required to provide the information necessary for BLM 

to conduct an analysis of air quality impacts for all 

relevant parameters when submitting their exploration 

APDs or field development project plans. BLM would 

use the information to determine the individual and 

cumulative impact on the reservations' air quality, 

disclose the analysis results in the appropriate NEPA 

document and consult with the tribes when the analysis 

shows impacts from a specific drilling or development 

proposal. 

Approval of exploration APDs and field development 

plans and the air quality new source review process 

would include conditions to prevent violations of 

applicable air quality laws, regulations and standards. 

Mitigating measures may include surfacing roads and 

well locations, applying dust suppressants, requiring 

operators to develop and enforce speed limits on 

project roads, minimizing construction of roads, 

requiring use of natural gas-fired and electric 

compressors and optimizing the number of wells 

connected to one compressor. 

Operators near the Reservation may be required to 

restrict the timing or location of CBNG development if 

monitoring or modeling by the air quality regulatory 

authority finds their CBNG development is causing or 

threatening to cause non-compliance with applicable 

local, state, tribal and federal air quality laws, 

regulations, standards and implementation plans.

To protect important hunting, fishing and plant 

gathering sites, the BLM would require operators in 

the area east of the Tongue River between Ashland and 

Birney to inventory BLM-administered surfaces for 

traditional plant gathering sites near the proposed 

drilling locations. APD approvals may include 

avoidance or timing restrictions to prevent impacts to 

identified important hunting, fishing and plant 

gathering sites depending on the developments' 

location. These measures would prevent potential 

impacts to subsistence living methods for tribal 

members. Migratory paths traditionally used by game 

to cross the Northern Cheyenne Reservation would be 

monitored as part of the Wildlife Monitoring and 

Protection Plan. If these impacts to migration routes 

result in a reduction of available game measures would 

be developed in consultation with the tribe to provide 

for wildlife migration. 

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All Alternatives

could occur under Alternative E. The number of 

CBNG workers driving across the reservations to reach 

well sites would be similar to Alternatives B, C and D; 

thus, the traffic, noise, safety, road maintenance and

worker interaction impacts on the Northern Cheyenne 

Reservation would be similar. To reduce effects of

speeding vehicles, operators of federal leases would be 

required to post and enforce speed limits on their 

employees, or employees of their contractors.

Conclusions

These surface water quality and quantity effects, when 

combined with the increases projected from similar 

current and planned CBNG development activities in 

Wyoming, would be less than those described in 

Alternative C. Water would be available for irrigators 

and tribal government water leasing activities would 

not be impaired. The groundwater would be protected 

as described in the Northern Cheyenne Mitigation 

Appendix. 

If the Northern Cheyenne and Crow tribes elected to 

develop their CBNG resources, impacts as described 

under Alternative B above would occur. 

Social and economic effects on the Crow and Northern 

Cheyenne tribes under this alternative would be similar 

to Alternatives B, C and D.

Alternative F—Phased Development 

Multiple Screens (High Range)

Air Quality Changes

Review of the air resource analysis indicated that 

Alternative F would have impacts on air quality 

similar, but less than Alternative E. The sources of 

CBNG generated emissions would be minor and 

widespread under Alternative F, particularly since 

development would be limited within any given 

watershed. There would be a more dispersed pattern of 

development across the region, thus the emissions 

would be less concentrated and more apt to disperse 

with little effect on human health and thus on 

environmental justice populations.

Groundwater Drawdown

Potential effects on groundwater drawdown would be 

similar to Alternatives B through E. Under Alternative 

F, federal APDs would be more dispersed throughout 

the region and limited in a given watershed in any

given year. Thus, groundwater drawdown would not 

likely be concentrated in any one area and affect low 

income or minority populations. 

Surface Water Quality

Surface water quality impacts under Alternative F 

would be similar or less than those described under 

Alternative E. While some discharge of untreated 
CHAPTER 4

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4-219

water would be allowed, the volume would be limited

to 10 percent of the 7Q10. If volumes exceed the 

allowable amount per watershed, then any additional 

federally produced water would be required to be 

injected, treated (including using impoundments), or 

put to a beneficial use. 

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All Alternatives

could occur under Alternative F. The number of CBNG 

workers driving across the reservations to reach well 

sites would be less than Alternatives B through E and 

similar to Alternative H because of phased development; 

thus, the traffic, noise, safety, road maintenance and

worker interaction impacts on the Northern Cheyenne 

Reservation would be similar. To reduce effects of 

speeding vehicles, operators of federal leases would be 

required to post and enforce speed limits on their 

employees, or employees of their contractors.

Avoidance and Mitigation Measures

In addition to the enhanced mitigation requirements 

listed for Alternative E that include conducting sitespecific hydrological studies, development of 

mitigation measures, monitoring techniques for water 

and air quality and POD preparation prior to APD 

approval, Alternative F would extend these 

requirements to any areas within 5 miles of the 

Reservation. 

The analysis and monitoring data would be required to

demonstrate that Indian Trust Assets on the Crow and 

Northern Cheyenne Reservations would not be 

affected by development of federal CBNG wells. If the 

analysis does not show protection of these assets, the 

BLM would hold tribal consultations to determine 

appropriate mitigation measures, which may include 

denying the APDs. 

The potential loss of royalties to the Federal 

government from a 5-mile buffer would be 

approximately $1.2 billion at current gas prices.

Monitoring wells and air monitoring stations may be 

required between the well development area and the 

reservations to ensure protection of reservation air and 

groundwater resources. If monitoring indicates impacts 

to ITAs on the Crow and Northern Cheyenne 

reservations, wells would be shut in. If CBNG 

development occurs on a reservation, this monitoring 

requirement may be modified in consultation with the 

tribes and other affected parties. Thus, Alternative F 

would be less likely than Alternative E to affect 

environmental justice populations, given the CBNG 

development requirements for resource analysis, 

mitigation and monitoring.

Implementation of the wildlife screen could lead to a 

situation where no CBNG development would occur 

within crucial sage-grouse habitat. This would lead to a 

loss of royalties to the Federal government of 

approximately $290 million at current gas prices. 

Conclusions

Surface water quality and quantity impacts when 

combined with undesirable effects from CBNG 

development in Wyoming would be less than those 

described under Alternative E. Generally, groundwater 

would be protected and impacts to ground and surface 

water quality/quantity would be limited. 

Social and economic effects on the Crow and Northern 

Cheyenne Tribes under this alternative would be 

similar to Alternatives B through E. 

Overall there is likely to be limited impacts on low 

income or minority populations under Alternative F. If 

the Crow and Northern Cheyenne tribes decided to 

develop their CBNG resources, potential impacts 

would occur as described under Alternative B.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Air Quality, Surface Water Quality and

Groundwater Drawdown

Air quality, groundwater drawdown, surface water 

quality and social and economic impacts would be 

similar to Alternative F; however, the magnitude of the 

impacts would be greatly reduced because of the lower 

number of wells that would be developed 

(approximately 65 percent fewer wells). Some 

watersheds would still experience more well 

development than other watersheds, but compared to 

Alternative F, the level of impact across the watersheds 

would be less under Alternative G. Since Alternative F 

is not anticipated to impact environmental justice

populations, Alternative G also would have little effect 

on these populations.

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All 

Alternatives could occur under Alternative G. This 

alternative would employ fewer workers because of the 

reduced number of wells that would be developed 

under Alternative G. This may result in fewer CBNG 

workers driving across the Northern Cheyenne 

Reservation than under Alternatives B thru E and F 
CHAPTER 4

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4-220

and H, thus the traffic, noise, safety, road maintenance

and worker interaction impacts on the reservation 

would be less. To reduce effects of speeding vehicles, 

operators of federal leases would be required to post 

and enforce speed limits on their employees, or 

employees of their contractors.

Avoidance and Mitigation Measures

Mitigation measures for well development on or in 

close proximity (within 5 miles) to the reservations 

would be the same as for Alternative F. However, due 

to the reduced number of wells that would be 

developed under this alternative, the potential loss of 

royalties to the Federal government from a 5-mile 

buffer would be about 65 percent less than for 

Alternative F (approximately $420 million).

Conclusions

While air quality, groundwater drawdown and surface 

water quality impacts would be similar to Alternative 

F, the magnitude of these impacts would be greatly 

reduced under this alternative, due to significantly less 

well development.

Social and economic effects on the Crow and Northern 

Cheyenne tribes under this alternative would be similar 

to but less than Alternatives B through F. 

Alternative H—Preferred Alternative - 

Multiple Screens

Air Quality Changes

Review of the air resource analysis indicated that 

Alternative H would have impacts on air quality 

similar to Alternative F. The sources of CBNG 

generated emissions would be minor and widespread 

under Alternative H, particularly since development 

would be limited within any given watershed. There 

would be a more dispersed pattern of development 

across the region, thus the emissions would be less 

concentrated and more apt to disperse with little effect 

on human health and thus on environmental justice

populations.

Groundwater Drawdown

CBNG production in Montana would result in the 

depletion of approximately 23 percent of the 

groundwater resources in the productive coal seams 

beneath Montana’s Powder River Basin (ALL 2001b). 

This drawdown would be basinwide and correspond to 

the geographical distribution of production wells. By 

implementing watershed-level analysis, water 

management planning and water balance projections as 

part of PODs, federal CBNG well development under 

Alternative H would be more dispersed throughout the 

region and limited in a given watershed in any given 

year as compared to Alternatives B through E. 

As for the other development alternatives, the 

occurrence potential is not localized and would not 

impact segregated portions of the population; the impact 

would be felt evenly across the region. Furthermore, the 

drawdown has the potential to reduce surface water 

flows in some drainages depending on specific site 

conditions. The availability of groundwater is important, 

as many rural families depend on the supply of 

groundwater for their household and ranch/agricultural 

(irrigation) applications.

Surface Water Quality

Due to the water screen, Alternative H would have 

impacts on water resources and water resource values 

similar to or less than the other development alternatives. 

This alternative would allow limited discharge of 

untreated water under certain conditions. The volume of 

discharge from federal wells would be based on 10 

percent limit of the 7Q10 flow calculated from all CBNG 

wells at the downstream end of the watershed. The 10 

percent would not apply if surface water monitoring is 

being conducted above and below the proposed outfalls. 

If surface water monitoring indicates a water quality 

threshold would be exceeded, no further untreated 

discharge would be allowed from federal wells upstream 

from the station. Previously approved water management 

plans may be modified or rescinded if monitoring 

indicates unacceptable impacts are occurring. Water 

quality thresholds and the surface water monitoring 

requirements are detailed in the Hydrology Appendix. If 

volumes exceed the allowable amount per watershed, 

then any additional federally produced water would be 

required to be injected, treated (including using 

impoundments), or put to a beneficial use.

Social and Economic Values

The same social and economic effects listed under 

Impacts from Management Common to All 

Alternatives could occur under Alternative H. The 

number of CBNG workers driving across the 

reservations to reach well sites would be less than

Alternatives B through E and similar to Alternative F 

because of phased development; thus, the traffic, noise, 

safety, road maintenance and worker interaction 

impacts on the Northern Cheyenne Reservation would 

be similar. To reduce effects of speeding vehicles, 

operators of federal leases would be required to post 

and enforce speed limits on their employees, or 

employees of their contractors.
CHAPTER 4

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Avoidance and Mitigation Measures

Alternative H incorporates the enhanced mitigation

requirements from Alternative F, which include 

conducting site-specific hydrological studies, 

development of mitigation measures, monitoring 

techniques for water and air quality, watershed-level 

analysis and additional air and groundwater analysis 

and tribal consultation for development proposed 

within 5 miles of the Crow or Northern Cheyenne 

reservations. Alternative H would also require the 

BLM to use the four resource screens, including air 

quality and Native American concerns, to evaluate 

PODs and on-going development prior to approval of 

additional APDs. 

Within 5 miles of either reservation, analysis and 

monitoring data would have to demonstrate how ITAs

on the Crow and Northern Cheyenne reservations 

would be affected from development of federal CBNG 

wells. If the analysis does not show protection of these 

assets, the BLM would hold tribal consultations to 

determine appropriate mitigation measures, which may 

include denying the APDs.

The potential loss of royalties to the Federal 

government from a 5-mile buffer would be 

approximately $1.2 billion at current gas prices.

Monitoring wells and air monitoring stations may be 

required to be installed between the well development 

area and the reservations. If monitoring indicates that 

Trust Assets on the Crow and Northern Cheyenne

reservations are not being protected, wells would be 

shut in. If CBNG development occurs on a reservation, 

this monitoring requirement may be modified in 

consultation with the tribe and other affected parties. 

Thus, Alternative H would be less likely than 

Alternative E to affect environmental justice

populations given the CBNG development 

requirements for resource analysis, mitigation and

monitoring.

If no development were to occur within crucial sagegrouse habitat, then the socio-economic effect would 

be similar to that described under Alternative F.

Conclusions

Surface water quality and quantity impacts, when 

combined with undesirable effects from CBNG 

development in Wyoming, would be less than those 

described under Alternative E. Generally, groundwater 

would be protected and impacts to ground and surface

water quality/quantity would be limited. Social and 

economic effects on the Crow and Northern Cheyenne 

Tribes under this alternative would be similar to 

Alternatives B through F.

If either the Northern Cheyenne Tribe or Crow Tribe

elects to develop their CBNG resources, the federal 5-

mile buffer zone would not be used to limit the effect 

on the reservation. An additional percentage of 

drawdown would be experienced across the basin 

watersheds from the Northern Cheyenne or Crow tribal 

developments (see Hydrological Resources section for 

details). If each tribe’s CBNG resources were drilled to 

the degree estimated in the RFFA (4,000 wells for each 

reservation), the depletion of the coal seam aquifer 

groundwater resource could increase across the region 

and cause a hardship on numerous low-income and 

minority populations, which are prevalent throughout 

the area. However, water well and spring mitigation

agreements required by the MBOGC, BLM and

TLMD would provide alternate sources of water due to 

groundwater lost to the drawdown of resources within 

the coal seam aquifers. Drawdown in non-producing 

coal seam aquifers is not anticipated. Replacement 

may not be possible in some areas with concentrated 

CBNG production. This represents a possible 

environmental justice issue if the non-replacement 

areas are adjacent to reservation boundaries and no 

suitable water is available for mitigation. 
CHAPTER 4

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Soils

Soils

Montana has a wide mix of geologic parent material, which 

produces a vast array of different soil types

Alternative A

No Action (Existing CBNG Management)

• There would be minor occurrences of soil erosion, runoff

and sedimentation, mostly during construction activities. 

• Approximately 1,500 acres would be disturbed short term 

during CBNG exploration and construction activities.

• 500 acres would be disturbed longer term during 

production, with a majority of the land reclaimed after 

production is ceased. 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• CBNG development would result in 55,400 acres being 

disturbed.

• 32,950 acres would be disturbed longer term during 

production, with a majority of the land reclaimed after 

production is ceased. 

• No impacts would occur to soils from CBNG waters.

Alternative C

Emphasize CBNG Development

• CBNG development activities would disturb 70,000 acres.

• Surface discharge and irrigation of produced water could 

result in detrimental impacts to soils. 

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Impacts would be similar to Alternative B with the 

exception that produced water would be treated prior to 

discharge and not injected.

• More water would be available for irrigation of 

agricultural land.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Impacts would be similar to Alternative B. There would 

be a slight increase in the level of disturbance due to the 

increased use of impoundments to contain produced 

water.

• Produced water would be available for beneficial use, 

including irrigation.

Alternative F

Phased Development Multiple Screens (High Range)

• Impacts would be similar to Alternative E, although some 

impacts would not occur or be delayed due to the 

implementation of cumulative and watershed specific 

numerical limits on the number of federal CBNG APDs 

approved per year.

• Produced water would be available for beneficial use, 

including irrigation

• CBNG development would result in approximately 55,150 

acres being disturbed. If no development occurs within the 

crucial sage-grouse habitat, then approximately 48,091

acres of disturbance would occur.

• An estimated 32,850 acres would be disturbed longer term 

during production, with a majority of the land reclaimed 

after production has ceased. Alternatively, if development 

does not occur in crucial sage-grouse habitat, then the 

acres of long-term disturbance is reduced to 28,645. 

Alternative G

Phased Development Multiple Screens (Low Range)

• Impacts would be similar to Alternative F, although 

impacts would be about 65 percent less due to the limit on 

the number of federal CBNG APDs (323 versus 910)

approved per year.

• Produced water would be available for beneficial use, 

including irrigation

Alternative H 

Preferred Alternative - Multiple Screens

• Impacts to soils would be similar to Alternative F.

• CBNG development would result in approximately 55,150 

acres being disturbed. 

• An estimated 32,850 acres would be disturbed longer term 

during production, with a majority of the land reclaimed 

after production has ceased. 

Assumptions

Surface disturbance assumptions are detailed in the 

Analysis Assumptions and Guidelines section of this 

chapter. This analysis is focused on the CBNG

emphasis area, but can be used by inference on 

similar areas in Montana. A more detailed discussion 

of soils is presented in the Soils Technical Report

(ALL 2001a).

Impacts From Management 

Common to All Alternatives

Impacts on soils would occur from various activities 

during the exploration, construction, operation and

abandonment of conventional oil and gas wells 

developed resulting in a loss of either soil resources 

or soil productivity. These impacts would include soil 

compaction under disturbed areas such as well sites 

and lease access roads, soil erosion in disturbed areas

and chemical impacts from spills of liquids. Some 

impacts would be unavoidable, such as those 

resulting from the construction of well sites. Other 

impacts would be mitigated by standard oil field 

practices, such as the use of berms around production 

facilities. Short-term impacts would occur typically 

during construction phases, including reclamation of 

construction sites.

Soils disturbed by the building of access roads, drill 

pads and pipelines would be prone to accelerated 
CHAPTER 4

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erosion because of the removal of protective 

vegetation and litter cover during construction 

activities. This protective cover would bind the soil, 

provide desirable surface texture for infiltration of 

water and air and protect the surface from water and 

wind erosion. Accelerated soil erosion would occur 

during the production phase in high traffic areas of 

the well pad or along access roads or in portions of 

the well pad that have not been properly graded. In 

areas where soils have high to severe erosion 

potential and are unstable, disturbance would result 

in accelerated erosion to the extent that damage to 

facilities and roadways may occur. Wind and water 

erosion on bare soil surfaces would cause more 

sedimentation in streams from runoff following 

rainfall or snowmelt. 

Impacts would be greatest on shallow soils of low 

productivity and on soils on moderately sloping to 

steep landscapes. Project activities would have 

minimal effect on slope stability because surface 

disturbance on slopes in excess of 30 percent would 

be avoided where possible. Where such disturbances 

cannot be avoided, mitigation measures required by 

MBOGC and BLM through the APD authorization 

process would be implemented to reduce erosion and 

protect watershed resources. BLM and TLMD lease 

stipulations would also be used to mitigate soil 

erosion. Eastern Montana suffers from excessive 

wind erosion primarily from dry soil, sparse 

vegetative cover and erodible soils.

Drilling activity-especially equipment transportwould cause soil compaction. The degree of 

compaction would be influenced by soil texture, 

moisture content, organic matter and soil structure. 

Soils with a mixture of sand, silt and clay compacts 

more than a soil with more uniform particle size. 

Coarse-textured sandy soils generally would be more 

compactable than fine-grained soils. Soil moisture 

would be the most critical factor in compaction. At 

field capacity, which is the amount of soil moisture 

remaining after a soil mass is saturated and allowed 

to drain freely for 24 hours, sufficient water remains 

in the pores to provide particle-to-particle lubrication 

and maximum compaction potential under load. 

Thus, moist but not wet soils would be most 

susceptible to compaction. 

Organic matter such as roots and humus would help 

reduce soil compaction. In general, the greater the 

organic matter content, the less compaction. 

Compaction would severely affect plant growth by 

inhibiting root penetration, limiting oxygen and 

carbon dioxide exchange between the root zone and 

the atmosphere and severely limiting the rate of water 

infiltration into the soil. Compaction of soils would 

inhibit reclamation and natural revegetation of 

disturbed areas. Loss of topsoil and a decrease in soil 

productivity from soil layer mixing and compaction 

would impact the natural vegetation supported in the 

area, which in turn may affect forage and habitat for 

wildlife and livestock. The use of off-road vehicles 

and heavy equipment would cause soil compaction, 

which will lead to increased surface runoff and 

subsequent erosion. Effects will be most severe when 

off-road vehicles and heavy equipment are used 

during moist and wet soils conditions.

With development, the potential for impacts to soil 

from drilling and produced fluids would increase. 

Soil contamination from conventional oil and gas 

development in Montana would result mainly from 

leaking and improperly reclaimed reserve/brine pits. 

Produced hydrocarbons and fuel spills would 

occasionally cause impacts. Spills generally would 

not be large and the materials would be relatively 

immobile. Toxic and saline concentrations from the 

spilled fluids would be capable of sterilizing the soil.

Construction disturbances from conventional oil and 

gas production would lead to the disturbance of 

approximately 12,650 acres (9,817.5 acres of BLMadministered surfaces and 2,832.5 acres of state 

lands) during the next 20 years. Revegetating parts of 

the well pads during production would reduce the 

area of disturbance to 4,600 acres. Most of these 

acres would be remediated after the hydrocarbons 

have been produced.

When siting impoundments, there are different soil 

characteristics one should consider before choosing a 

location. Understanding the existing soil conditions, 

both at the surface and at depth, will aid operators 

during impoundment siting and design. Site-specific 

soils analyses, including soil salinity, soil K- factors, 

textures, slope, soil classification, Atterberg limits, 

location and extent of rock strata and permeability, 

can assist operators to determine the areas most 

suited for construction of impoundments. 

Information should be obtained regarding the types of 

soils present near impoundments, relative to the clay 

content, cation-exchange capacity and the percentage 

of certain soluble mineral assemblages in the soils, 

each of which can cause changes to the infiltrating 

water chemistry. Clay mineralogy can affect 

impoundment design considerations. For instance, 

within the Powder River RMP, the clays that 

compose the surface soils are predominantly smectite 

clays (montmorillonite family), a clay mineral 

commonly referred to as a “swelling” clay. The 

swelling nature of smectite is a result of its ability to 

take water into the clay’s internal structure resulting 

in the expansion or swelling of the clay mineral. This 
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swelling can result in decreased porosity and 

permeability of the soils which could cause 

infiltration rates under impoundments to decrease 

considerably. 

Cation exchange capacity (CEC) is a soil property 

attributed to the type and quantity of clay minerals 

and organic matter present in a soil and is the degree 

to which the soil particles are capable of attracting 

and holding positively charged (cation) ions on their 

surface. Soils with lower CEC potential would result 

in greater geochemical changes to infiltrating water. 

Gypsum and CaCO3 (calcite) can affect the quality of 

infiltrating water. Soils analyses, including soil 

salinity, soil K- factors, textures, slope, soil 

classification, Atterberg limits, location and extent of 

rock strata and permeability, can assist operators to 

determine the areas most suited for construction of an 

impoundment. The Soils Appendix provides 

additional information about soils in the Planning 

Area.

Areas would be reclaimed as prescribed by an 

approved reclamation plan that includes revegetation 

to reduce soil erosion. Most soil disturbances and 

related erosion would begin to be mitigated within 

25 days after drilling the well. Exceptions would be 

sites with severe characteristics (slope and physical 

and chemical nature of the soils) or sites where saline 

water spills or site contamination have occurred. 

These sites may take longer to remediate because 

special erosion control seeding or remediation 

measures may be necessary to achieve successful 

reclamation. These impacts may result in a loss of 

either soil resources or soil productivity.

Saline water would have a more persistent and 

detrimental effect on soil productivity. There would 

be some loss of soil through erosion as a result of 

surface disturbance, but this would be minimized 

with an approved surface use plan.

Additional disturbances would occur from coal 

mining in the CBNG emphasis area, which is 

estimated at a total of 49,500 acres.

Prime Farmland

If prime farmland exists on federal or state surface 

where CBNG development is proposed, the same 

type of reclamation plan would be developed. A 

difference would be that more topsoil probably would 

be available for reclamation purposes on a prime 

farmland site and would be identified in the 

reclamation plan prior to development.

If the site proposed for development were private 

surface, then the reclamation plan would be 

developed in consultation with and according to the 

wishes of the private landowner. Most likely, the 

reclamation plan on Federal versus state and private 

surface would be very similar.

No prime farmlands are known to exist on the federal 

surface. Privately owned prime farmlands over 

federal and state leases that are impacted by roads or 

site development would be reclaimed in accordance 

with consultation with the private surface owner. 

This situation would be same for all alternatives.

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG

Management)

Impacts on soils may occur from various activities 

during the exploration, construction, operation and

abandonment of CBNG wells developed for the 

project and may result in a loss of either soil 

resources or soil productivity. The primary concerns 

include increased soil erosion, loss of topsoil, mixing 

of soil horizons, compaction and contamination of 

soils from various pollutants. These impacts may 

result in a loss of either soil resources or soil 

productivity.

Under this alternative, all CBNG water on BLMadministered land would be contained or beneficially 

used at the well site, while all CBNG water on private 

lands would be discharged under the existing 

MPDES permit into the Tongue River (up to 1,600 

gpm), impounded, or used for dust control at on-site 

coal mines.

Exploration

Under Alternative A for BLM-administered surfaces, 

approximately 400 acres would be disturbed for 

exploratory wells. On state and private lands, 

approximately 275 acres would be disturbed during 

exploration. All produced CBNG water during 

exploration will be contained; therefore, there would 

be no impacts to soils caused by high saline/sodium 

water applications.

Production

There will be no CBNG production on BLMadministered surfaces and therefore no impacts from 

production. Only state and private lands will have 

CBNG production. During the construction of the 

well sites, access roads, utilities and other facilities, 

812 acres of soils will be disturbed. Revegetating 

parts of the well pads during production would 

reduce the state and private soil disturbances to 500 
CHAPTER 4

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4-225

acres. Production water may be discharged to surface 

waters in accordance with the existing MPDES 

Discharge Permits that allow discharge between 

3,300 and 4,200 gpm into the Tongue River. This 

small increase in flow volume is not considered 

sufficient to cause added erosion to stream banks or 

streambeds. Produced water may also be used 

beneficially by industry and landowners, or stored in 

impoundments onsite. If the quality of the water were 

acceptable (not too high in SAR or salinity), there 

would be little or no additional impacts to soils from 

managed irrigation. If the quality of land-applied 

water were detrimental, further mitigation measures

would need to be implemented to reduce the impacts 

to soils (ALL 2001a).

Abandonment

After reclaiming the exploratory wells, there will be 

500 acres of soil disturbed long-term-all on state and 

private lands. The area will be reclaimed as 

prescribed by an approved reclamation plan including 

revegetation to reduce soil erosion. Soils would be 

stabilized by vegetative cover and erosion eliminated 

within 2 to 5 years following the beginning of 

reclamation. Exceptions may be sites with severe 

characteristics (slope and physical and chemical 

nature of the soils) or sites where saline water spills 

or site contamination have occurred. These sites may 

take longer to remediate because special erosion 

control seeding or remediation measures may be 

necessary to achieve successful reclamation. 

There may be some irretrievable loss of soil through 

erosion as a result of surface disturbance, but this can 

be minimized with a well-developed and approved 

surface use plan. Soil beneath unlined surface 

impoundments would also require extensive 

reclamation because of accumulation of sodium 

during infiltration of water. The soils structure could 

be damaged severely, plant growth would be minimal

and accumulation of salt in the soils would likely lead 

to the soil being treated in-situ or removed and 

disposed.

Crow Reservation

There would be no impacts to the soils on the Crow 

Reservation from regional CBNG development. 

Northern Cheyenne Reservation

There would be no impacts on the Northern 

Cheyenne Reservation soils from regional CBNG

development. 

Conclusion

During the next 20 years, disturbances from limited 

CBNG development and exploration, conventional 

oil and gas development, coal mining and other 

projects considered under the cumulative effects 

analysis would result in the disturbance of about 

37,500 acres of soil. These disturbances would be 

reduced to about 36,500 acres during the production 

phase of CBNG, conventional oil and gas activities

and coal mining. 

After production ceases and lands used for 

production and mining are abandoned, most land can 

be returned to production (excluding permanent roads 

and facilities). There would be minimal unavoidable, 

irreversible and irretrievable impacts to soils. There 

would be a temporary increase in soil erosion, runoff

and sedimentation, mostly during construction 

activities. If the qualities of land-applied or 

impounded waters were acceptable, there would be 

little or no impacts to soils; but if water quality is 

detrimental, additional mitigation measures would 

need to be implemented.

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Impacts to soils would be reduced under this 

alternative by requiring transportation corridors; 

using a single trench for utilities and piping; using 

multiple completions per well bore and directional 

drilling; using temporary tank storage and injection

of all produced CBNG water; and rehabilitating new 

roads at the end of the well lifetime. All of these 

mitigation measures would help to minimize the area 

of surface disturbances, which would be up to a 

35 percent or higher reduction in soil disturbances.

Exploration

Under this alternative, approximately 850 acres of 

BLM-administered surfaces would be disturbed for 

exploratory wells. On state and private lands, 

approximately 1,000 acres would be disturbed during 

exploration. All produced CBNG water during 

exploration will be contained; therefore, there would 

be no impacts to soils caused by high saline/sodium 

water applications. Losses from exploration would be 

mostly temporary and would be reclaimed after 

exploration activities cease.

Production

During the construction of the well sites, access

roads, utilities and other facilities, 25,600 acres of 
CHAPTER 4

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BLM-administered soils and 29,750 acres of state 

and private soils will be disturbed. Revegetating parts 

of the well pads during production would reduce the 

BLM soil disturbances to 15,250 acres and state and 

private soil disturbances to 17,700 acres. Production 

water will be injected; therefore, no impacts to soils 

from CBNG waters will occur. 

Abandonment

Reclaiming all of the exploratory wells would 

provide vegetation cover to 1,850 acres of disturbed 

soils. Additional reclamation activities at the 

production wells and utility right-of-ways (ROWs) 

would further establish vegetation cover to these 

previously disturbed soils. The disturbed areas would 

be reclaimed as prescribed by an approved 

reclamation plan including revegetation to reduce soil 

erosion. Soils would be recovered and erosion halted 

within 2 to 5 years, following the beginning of 

reclamation. Exceptions may be sites with severe 

characteristics (slope and physical and chemical 

nature of the soils). There may be some irretrievable 

loss of soil through erosion as a result of surface 

disturbance, but this can be minimized with a welldeveloped and approved surface use plan.

Crow Reservation

There are no tribal sponsored CBNG developments 

anticipated for the reservation; however, there is the 

possibility of on-reservation private or private lands 

being developed in small pockets. These small onreservation developments are expected to impact the 

soils in proximity to the wells and associate 

infrastructure in a similar fashion as describe above 

in general for Alternative B. 

Northern Cheyenne Reservation

There would be no impacts on the Northern 

Cheyenne Reservation soils from regional CBNG

development. It is not anticipated there would be any 

tribal sponsored CBNG development on the 

reservation nor areas of private development. 

Conclusion

During the next 20 years, disturbances from CBNG

development, conventional oil and gas development, 

coal mining and other projects considered under the 

cumulative effects analysis would result in the 

disturbance of about 117,150 acres of soil. These 

disturbances would be reduced to about 84,700 acres 

during the production phase of CBNG, conventional 

oil and gas activities and coal mining. After 

production ceases and lands used for production and 

mining are abandoned, most land can be returned to 

production (excluding permanent roads and 

facilities). There would be minimal unavoidable, 

irreversible and irretrievable impacts to soils. There 

would be a temporary increase in soil erosion, runoff

and sedimentation, mostly during construction 

activities.

Development of the Crow and Northern Cheyenne 

reservations would disturb an initial 24,200 acres or 

12,100 acres per reservation. Following the same 

reclamation measures as commercial CBNG

development, the disturbances would be reduced by 

nearly 10,000 acres. Each reservation would have a 

residual 7,200 acres of disturbed soils around well 

pads, access roads, utility corridors and water 

management facilities. 

Alternative C—Emphasize CBNG

Development

Under this alternative, impacts on soils would be 

similar to Alternative B with the following 

exceptions:

• Untreated CBNG discharge water could be used 

for managed irrigation

• The discharge of produced water to the ground 

surface would increase erosion

• There would be a 35 percent increase in 

impacted soils due to specific management 

practices for transportation routes

The long-term impacts of using CBNG water or 

diluted discharge water for agricultural purposes 

include crop effects, farming practice changes, 

irrigation management and direct effects to soils. 

Based on the generally fine texture of the surface 

soils (clayey) in the emphasis area, much of the soil 

would likely be susceptible to increasing sodicity 

when irrigated or land applied with water having a 

high SAR (generally greater than 3 for some soils and 

greater than 12 for others). If sodic water is applied to 

these soils, the probability of soil dispersion 

(deflocculation) is high, causing infiltration and 

drainage decreases. The long-term consequence is an 

anaerobic, waterlogged, saline/sodic soil, which 

would be difficult to reclaim. Those soils with a 

coarser texture (sandy to loamy) and good internal 

drainage will be the least susceptible to increasing 

sodicity and salinity. 

Dispersed soil would also be subject to accelerated 

erosion leading to gullying, increased sedimentation

and harm to riparian vegetation and aquatic habitats. 

The native species composition in these affected
CHAPTER 4

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4-227

areas also will change. CBNG water discharge will 

have the cumulative effect of encouraging the 

establishment and proliferation of non-native and 

noxious weed species. As noted in the Soils 

Technical Report (ALL 2001a), there are fewer 

irrigated than non-irrigated acres along the Tongue 

and Powder Rivers, which, based on the RFD, is 

where a majority of the potential CBNG activity 

would reside. However, if adequate water and 

suitable agricultural soils were available in areas 

adjacent to production, more irrigated land would be 

available for production and use. 

The use of high salinity/sodium CBNG water may 

have long-term effects on crops, limiting crops to 

those that are more salt tolerant. Additional irrigation 

water would be required for leaching to ensure salts 

are moved out of the root zone. Increasing the 

frequency of irrigation may also need to be 

implemented to maintain soil water content and to 

decrease the effects of applying saline water (lower 

water-holding capacity and higher salinity levels). 

These increases in irrigation water amounts would 

lead to producers having to file for additional water 

rights or finding other sources of lower salinity water 

for leaching, as well as a potential for more saline 

seeps in areas irrigated with CBNG water. The Soils 

Technical Report (ALL 2001a) discusses the impacts 

of discharging CBNG waters to soils in more detail.

Exploration

Under this alternative, impacts on soils would be 

similar to Alternative B, except water generated by 

testing CBNG wells could be discharged to surface 

waters and the land surface-with impacts as discussed 

above.

Production

Under this alternative, impacts on soils would be 

similar to Alternative B, except untreated water 

generated during production could be discharged to 

surface water with appropriate permits and to the 

land surface at the well pad. Impacts of managed 

irrigation of CBNG waters are discussed above.

Abandonment

Under this alternative, impacts on soils would be 

similar to Alternative B. Roads would be 

rehabilitated and closed. The use of unlined 

impoundments would have impacts similar to those 

mentioned in Alternative A.

Crow Reservation

The Crow Reservation would not experience impacts 

to soils being irrigated with waters from the Bighorn 

or Little Bighorn rivers. Impacts associated with onreservation private lands would be similar to those 

described in general for Alternative B. In addition, 

impacts associated with direct discharge practices as 

described for Alternative C would be expected for 

these wells. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be expected to soils being irrigated with 

waters from the Tongue River and Rosebud Creek. 

Since these waterbodies would experience increases 

in their SAR and EC values, it is conceivable that 

tribal irrigators would also experience the types of 

soil impacts described in general for Alternative C. 

Soils impacts from tribal sponsored development on 

the reservation are not anticipated for this alternative.

Conclusion

Cumulative impacts would be similar to 

Alternative B, except that the surface disturbances 

would increase by up to 35 percent and surface 

discharge and irrigation of produced water would 

increase detrimental impacts to soils. Saline water 

has a more persistent and detrimental effect on 

plants’ ability to extract water. Cumulative 

disturbances from all regional projects would result 

in the disruption of about 138,360 short-term acres of 

soil. These disturbances would be reduced to about 

105,900 acres during the production phase of CBNG, 

conventional oil and gas activities and coal mining. 

One advantageous side effect would be that more 

water would be available for irrigation if acceptable 

agricultural land is available, but if acceptable 

qualities of water are not used, there could be an 

increased detrimental impact on additional soils.

Soil disturbance levels on the Crow and Northern 

Cheyenne Reservations would be similar to those 

discussed in the Conclusions section of Alternative 

B, (12,100 – 7,200 acres); however, they are 

expected to be somewhat increased due to the surface 

discharge of production water. 

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Under this alternative, impacts on soils would be 

similar to Alternative B except that produced water 
CHAPTER 4

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4-228

would be treated prior to discharge onto the surface 

or for irrigation and not injected, which would reduce 

the detrimental impacts caused by application of 

high-SAR water to soils.

Exploration

Under this alternative, impacts on soils would be 

similar to Alternative B, except that water generated 

by testing CBNG wells would be treated prior to 

discharge to surface waters and the land surface 

(instead of injection), which lessens the impacts 

caused by application of high-SAR water to soils.

Production

Under this alternative, impacts on soils would be 

similar to Alternative B, except water generated 

during production would be treated prior to discharge 

to the land surface and to surface water-with 

appropriate permits. Impacts of the managed 

irrigation of CBNG waters are discussed above.

Abandonment

Under this alternative, impacts on soils would be 

similar to Alternative B. Roads would remain open or 

closed at surface owner’s discretion. The use of 

unlined impoundments would have impacts similar to 

those mentioned in Alternative A.

Crow Reservation

The only soils impacted on the Crow Reservation

would be from on-reservation private developments 

similar to those previously described in Alternative 

B.

Northern Cheyenne Reservation

There would be no impacts to soils on the Northern 

Cheyenne Reservation from regional CBNG

development. Lands irrigated with waters from either 

Rosebud Creek or the Tongue River are not expected 

to be impacted, since production water will be treated 

prior to discharge. 

Conclusion

Cumulative impacts would be similar to 

Alternative B with the exception that produced water 

would be treated prior to discharge onto the surface 

and not injected, which would reduce the detrimental 

impacts caused by application of high-SAR water to 

soils.

Soils disturbance levels on the Crow and Northern 

Cheyenne reservations would be similar to those 

discussed in the Conclusions section of Alternative 

B, (12,100 – 7,200 acres). 

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Under this alternative, impacts on soils would be 

similar to Alternative B except produced water would 

be managed per a site-specific Water Management 

Plan with first priority being beneficial use of 

produced water; impoundments designed to minimize 

or mitigate impacts to soil, water and vegetation; an 

option for injection of CBNG water; and no 

degradation of a watershed. All of these factors 

would reduce the detrimental impacts caused by 

application of high-SAR water to soils. There would 

be a 35 percent increase in impacted soils over 

alternatives B and D due to specific management 

practices for transportation routes-this percent will 

vary depending on site-specific Project Plans for 

ROWs agreed upon with the surface owners.

Exploration

Under this alternative, impacts on soils would be 

similar to Alternative B, except that water generated 

by testing CBNG wells would not be allowed to 

degrade the watershed, which lessens the impacts 

caused by application of high-SAR water to soils.

Production

Under this alternative, impacts on soils would be 

similar to Alternative B, except water generated 

during production would be beneficially used, stored 

in impoundments, or discharged without impacts to 

the watershed. Impacts of the managed irrigation of 

CBNG waters are discussed above.

Abandonment

Under this alternative, impacts on soils would be 

similar to Alternative B. Roads would remain open or 

closed at surface owner’s discretion. The use of 

unlined impoundments would have impacts similar to 

those mentioned in Alternative A.

Crow Reservation

The Crow Reservation would not experience impacts 

to soils being irrigated with waters from the Bighorn 

or Little Bighorn rivers. Impacts associated with onreservation private lands would be similar to those 

described in general for Alternative B. 
CHAPTER 4

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Northern Cheyenne Reservation

There would be no impacts to soils on the Northern 

Cheyenne Reservation from regional CBNG

development. Lands irrigated with waters from either 

Rosebud Creek or the Tongue River are not expected 

to be impacted, since only slight alterations in surface 

water quality are anticipated.

Conclusion

Cumulative impacts would be similar to 

Alternative B with the exception that produced water 

would be managed per a site-specific Water 

Management Plan that would be geared toward 

minimizing impacts to soil, water and vegetation and

surface owners would have more input in the Project 

Plan for the transportation corridors. Cumulative 

disturbances from all regional projects would result 

in the disruption of about 135,600 short-term acres of 

soil. These disturbances would be reduced to about 

95,800 acres during the production phase of CBNG, 

conventional oil and gas activities and coal mining. 

Soils disturbance levels on the Crow and Northern 

Cheyenne reservations would be similar to those 

discussed in the Conclusions section of Alternative

B, (12,100 – 7,200 acres). It is anticipated the tribes 

would manage or require their produced water to be 

managed in a similar manner to what will be required 

of off-reservation commercial CBNG developers. 

With this assumption no additional impacts to 

reservation soils are anticipated from on-reservation 

development.

Alternative F—Phased Development 

Multiple Screens (High Range)

Under this alternative, impacts on soils would be 

similar to Alternative B except the impacts to soils 

would be delayed due to the phased approach used by 

the BLM in the approval of APDs based on the 

number of federal APDs approved each year and

within each 4th Order Watershed. These combined 

limits would serve to level the impacts over a 23 year 

development timeframe thus eliminating periods of 

high impact due to peak development. The leveling 

of development resulting from a phased approach 

would reduce the overall detrimental impacts caused 

by the application of high SAR water to soils. 

Soils on the Crow and Northern Cheyenne

reservations would not be impacted by CBNG 

development off of the reservations unless the tribes 

approved certain activities, such as irrigation or 

impoundment construction, to occur on the 

reservations. Impacts to soils from such activities 

would be the same as described in Alternative C.

Exploration

Under this alternative, impacts on soils would be 

similar to Alternative B. 

Production

Under this alternative, impacts on soils would be 

similar to Alternative B, except the impacts would be 

spread over a longer period of time and the 

restrictions on volumes of untreated discharge waters 

in 4th Order watersheds may slightly reduce impacts 

to soils in the riparian zone. 

Abandonment

Under this alternative, impacts on soils would be 

similar to Alternative B, except for the impact being 

spread out over a longer period of time. 

Crow Reservation

The Crow Reservation would not experience impacts 

to soils being irrigated with waters from the Bighorn 

or Little Bighorn rivers. Impacts associated with onreservation private lands would be similar to those 

described in general for Alternative B. 

Northern Cheyenne Reservation

Similar to Alternative B, there would be no impacts 

to soils on the Northern Cheyenne Reservation from 

regional CBNG development. Lands irrigated with 

waters from either Rosebud Creek or the Tongue 

River are not expected to be impacted since limits 

would be in place on the volume of untreated CBNG 

water that could be discharged from the development 

of federal minerals. 

Conclusion

Under this alternative, cumulative impacts would be 

similar to Alternative B with the exception that 

impacts would be delayed due to the implementation 

of cumulative and watershed specific numerical 

limits on the number of federal CBNG APDs 

approved per year. Cumulative disturbances from all 

regional projects would be similar to Alternative B 

which would result in the disruption of about 117,050

short-term acres of soil. These disturbances would be 

reduced to about 84,600 acres during the production 

phase of CBNG, conventional oil and gas activities

and coal mining. Soils disturbance levels on the Crow 

and Northern Cheyenne reservations would be 

similar to those discussed in the Conclusions section 

of Alternative B (12,100 – 7,200 acres). It is 

anticipated the tribes would manage or require their 

produced water to be managed in a similar manner to 
CHAPTER 4

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what will be required of off-reservation commercial 

CBNG developers. With this assumption no 

additional impacts to reservation soils are anticipated 

from on-reservation development.

As with most other impacts described under this 

alternative, if crucial sage-grouse habitat areas are 

not developed, the overall impacts to soils would be 

reduced by a factor of approximately 12.8 percent 

within the development area. While some level of 

development is anticipated within these areas, it is 

likely to be less dense than the 80-acre spacing 

accounted for in other alternatives.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Under this alternative, impacts on soils would be 

similar to Alternative F except they would be reduced 

by approximately 65 percent based on the fewer 

number of APDs predicted to be issued. Under 

Alternative G, the annual cumulative limit placed on 

federal APDs approved by BLM would be set at five

percent (323 APDs) of the low-range number of state, 

private and federal CBNG APDs (6,470) predicted to 

be approved in the RMP areas (as identified in the 

Reasonably Foreseeable Development scenario in the 

Statewide document). A limit would also be 

established on the number of federal APDs approved 

each year within each 4th Order Watershed. This 

limit would be set at the total number of wells 

predicted for each watershed times the predicted rate 

of development in the Statewide document. These 

combined limits would serve to level the potential

impacts to soils over a 23 year development period. 

Soils on the Crow and Northern Cheyenne

reservations would not be impacted by CBNG 

development off of the reservations unless the tribes 

approved certain activities, such as irrigation or 

impoundment construction, to occur on the 

reservations. Impacts to soils from such activities 

would be the same as described in Alternative C.

Exploration

Under this alternative, impacts on soils would be 

similar to Alternative F. 

Production

Under this alternative, impacts on soils would be 

similar to Alternative F except that they would be 

reduced by approximately 65 percent due to the 

lower level of predicted development.

Abandonment

Under this alternative, impacts on soils would be 

similar to Alternative F except that they would be 

reduced by approximately 65 percent due to the 

lower level of predicted development.

Crow Reservation

The Crow Reservation would not experience impacts 

to soils being irrigated with waters from the Bighorn 

or Little Bighorn rivers. Impacts associated with onreservation private lands would be similar to those 

described in Alternative F. 

Northern Cheyenne Reservation

Similar to Alternative F, there would be no impacts 

to soils on the Northern Cheyenne Reservation from 

regional CBNG development. Lands irrigated with 

waters from either Rosebud Creek or the Tongue 

River are not expected to be impacted since limits 

would be in place on the volume of untreated CBNG 

water that could be discharged from the development 

of federal minerals. 

Conclusion

Under this alternative, cumulative impacts would be 

similar to Alternative F with the exception that 

impacts would be reduced by approximately 65

percent due to the lower level of predicted 

development.

As in Alternative F, it is anticipated the tribes would 

manage or require their produced water to be 

managed in a similar manner to what will be required 

of off-reservation commercial CBNG developers. 

With this assumption no additional impacts to 

reservation soils are anticipated from on-reservation 

development.

Alternative H—Preferred Alternative - 

Multiple Screens

Under this alternative, impacts on soils would be 

similar to Alternative F; however, the use of the 

multiple screens would serve to level the impacts 

over the development period thus eliminating periods 

of high impact due to peak development. The

leveling of development would reduce the overall

detrimental impacts caused by the application of high

SAR water to soils. 

Impacts to soils would be further reduced under this 

alternative by requiring long-term planning for 

transportation corridors and utility ROWs; using 

multiple completions per well bore and directional 
CHAPTER 4

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4-231

drilling; and rehabilitating new roads at the end of the 

well lifetime. All of these would help to minimize the 

area of surface disturbances, which would result in an 

approximate 25 percent reduction in soil 

disturbances.

Under this alternative produced water would be 

managed per a site-specific Water Management Plan 

with first priority being beneficial use of produced 

water; impoundments designed to minimize or 

mitigate impacts to soil, water and vegetation; an 

option for injection of CBNG water; and no 

degradation of a watershed. All of these factors 

would reduce the detrimental impacts caused by 

application of high-SAR water to soils. 

Soils on the Crow and Northern Cheyenne

reservations would not be impacted by CBNG 

development off of the reservations unless the tribes 

approved certain activities, such as irrigation or 

impoundment construction, to occur on the 

reservations. Impacts to soils from such activities 

would be the same as described in Alternative C.

Exploration

Under this alternative, approximately 850 acres of 

BLM-administered surface would be disturbed for 

exploratory wells. On state and private lands, 

approximately 1,000 acres would be disturbed during 

exploration. All produced CBNG water during 

exploration will be contained; therefore, there would 

be no impacts to soils caused by high saline/sodium 

water applications. Losses from exploration would be 

mostly temporary and would be reclaimed after 

exploration activities cease.

Production

Under this alternative, impacts on soils would be 

spread over a slightly longer period of time, 

development would occur at a more level rate and the 

restrictions on volumes of untreated discharge waters 

in 4th Order watersheds would be imposed, resulting 

in a marked reduction of impacts to soils. 

Furthermore, consolidated transportation and utility 

planning for the construction of the well sites, access

roads, powerlines, pipelines and other facilities, 

would reduce the amount of soils disturbed. 

Revegetating parts of the well pads during production 

would further reduce the BLM soil disturbances. 

Water generated during production would be 

beneficially used, stored in impoundments, or 

discharged without impacts to the watershed. 

Abandonment

Under this alternative, impacts on soils would be 

spread out over a longer period of time thus delaying 

some reclamation activities. Reclaiming all of the 

exploratory wells would provide initial vegetative

cover to disturbed soils. Additional reclamation 

activities at the production wells and utility ROWs 

would further establish vegetative cover to these 

previously disturbed soils. The disturbed areas would 

be reclaimed as prescribed by an approved 

reclamation plan including revegetation to reduce soil 

erosion. Soils would be recovered and erosion 

minimized within two to five years, following the 

beginning of reclamation. Exceptions may be sites 

with severe characteristics (slope and physical and 

chemical nature of the soils) or sites where saline 

water spills or site contamination have occurred. 

These sites may take longer to remediate because 

special erosion control seeding or remediation 

measures may be necessary to achieve successful 

reclamation. There may be some irretrievable loss of 

soil through erosion as a result of surface disturbance, 

but this can be minimized with a well-developed and 

approved surface use plan.

Soil beneath unlined surface impoundments would 

require extensive reclamation because of the

accumulation of sodium during infiltration of water. 

The soils structure could be damaged severely, plant 

growth would be minimal and accumulation of salt in 

the soils would likely lead to the soil being treated insitu or removed and disposed.

Crow Reservation

The Crow Reservation would not experience impacts 

to soils being irrigated with waters from the Bighorn 

or Little Bighorn rivers. Impacts associated with onreservation private lands are expected to impact the 

soils in proximity to the wells and associated 

infrastructure in a similar fashion as described above 

in general. 

Northern Cheyenne Reservation

Similar to Alternative F, there would be no impacts 

to soils on the Northern Cheyenne Reservation from 

regional CBNG development. Lands irrigated with 

waters from either Rosebud Creek or the Tongue 

River are not expected to be impacted since limits 

would be in place on the volume of untreated CBNG 

water that could be discharged from the development 

of federal minerals. It does not appear there would be 

any tribally-sponsored CBNG development on the 

reservation nor areas of private development in the 

near future. However, if development were to be 
CHAPTER 4

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4-232

initiated on the reservation soil impacts would be in 

proximity to the wells and associated infrastructure in 

a similar fashion as described under this alternative in 

general. 

Conclusion

Cumulative disturbances from all regional projects 

would be similar to Alternative F which would result 

in the short-term disruption of about 117,050 acres of 

soil. These disturbances would be reduced to about 

84,600 acres during the production phase of CBNG, 

conventional oil and gas activities and coal mining.

After production ceases and lands used for 

production and mining are abandoned, most land can 

be returned to production (excluding permanent roads 

and facilities). There would be minimal unavoidable, 

irreversible and irretrievable impacts to soils. There 

would be a temporary increase in soil erosion, runoff

and sedimentation, mostly during construction 

activities.

Produced water would be managed per a site-specific 

Water Management Plan geared toward minimizing 

impacts to soil, water and vegetation and surface 

owners would have more input in the Project Plan for 

the transportation corridors. 

Development of CBNG on the Crow and Northern 

Cheyenne reservations would disturb an initial 

24,200 acres or 12,100 acres per reservation. 

Following the same reclamation measures as 

commercial CBNG development, the disturbances 

would be reduced by nearly 10,000 acres. Each 

reservation would have a residual 7,200 acres of 

disturbed soils around well pads, access roads, utility 

corridors and water management facilities. It is 

anticipated the tribes would manage or require their 

produced water to be managed in a similar manner to 

what will be required of off-reservation commercial 

CBNG developers. With this assumption no 

additional impacts to reservation soils are anticipated 

from on-reservation development.
CHAPTER 4

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4-233

Solid and Hazardous Waste

Solid and Hazardous Wastes

Solid and hazardous wastes are under the jurisdiction of the 

MDEQ for RCRA wastes, MBOGC for RCRA exempt wastes

and the EPA for wastes generated on tribal lands

Alternative A

No Action (Existing CBNG Management)

• Typical solid waste refuse can be disposed of in local 

landfills. 

• Drilling mud and cuttings can be disposed of onsite with 

the landowner’s permission. 

• Minor impacts would also occur from the use of pesticides 

and herbicides during access and construction activities

Alternatives B, C, D, E, F and G

• Impacts for Alternative B, C, D, E, F and G would include 

increased quantities of waste requiring onsite disposal or 

transport to commercial landfills.

• Oil and gas developers are responsible for any damages to 

property, real or personal, resulting from the lack of 

ordinary care during operations. Operators are required to 

maintain SPCC plans and immediately remove any spilled 

or unused non-exempt wastes from the sites.

• No long term impacts to private, state or federal lands 

would occur from waste products associated with CBNG

development. 

Alternative H 

Preferred Alternative - Multiple Screens 

• Typical solid waste refuse can be disposed of in local 

landfills. 

• Drilling mud and cuttings can be disposed of onsite with 

the landowner’s permission. 

• Minor impacts would also occur from the use of pesticides 

and herbicides during access and construction activities

• Impacts would include increased quantities of waste 

requiring onsite disposal or transport to commercial 

landfills.

• Oil and gas developers are responsible for any damages to 

property, real or personal, resulting from the lack of 

ordinary care during operations. Operators are required to 

maintain Spill Prevention Control and Countermeasures 

(SPCC) plans and immediately remove any spilled or 

unused non-exempt wastes from the sites.

• No long term impacts to private, state or federal lands 

would occur from waste products associated with CBNG 

development.

Assumptions

All wastes generated by oil and gas operations 

including CBNG that are Resource Conservation and 

Recovery Act of 1976 (RCRA)-classified wastes, 

such as paint wastes or RCRA-exempt wastes such as 

drilling wastes, would be disposed of in accordance 

with regulations. Any release of a hazardous material 

would be reported in a timely manner to the relevant 

agency or to the BLM via a Report of Undesirable 

Event (NTL-3A). Any release of a CERCLA 

substance would be reported in accordance with 

regulations.

Impacts From Management 

Common to All Alternatives

Typical solid waste refuse would be generated by oil 

and gas drilling operations and can be disposed of in 

local landfills. The largest volume of waste generated 

from drilling activities would be from the drilling 

mud and cuttings generated. These drilling wastes 

would be exempt from RCRA and are considered 

non-hazardous. Drilling mud containing less than 

15,000 mg/l TDS can be disposed of on-site with the 

landowner’s permission. The amount of waste 

generated should not exasperate the landfills in the 

area. Other impacts would result from spills of waste 

during maintenance activities, including waste oil 

from generators, paint waste from construction 

activities and other solid wastes from construction 

activities. Impacts would also occur from the use of 

pesticides and herbicides during access and 

construction activities.

The TRR plans to principally transport coal; any 

potentially hazardous chemicals and materials would 

only be those associated with its operation of the 

railroad as a coal transporter. Petrochemicals, such as 

diesel fuel and lubricants, would be the primary 

hazardous materials involved in operating such a 

train. Given the route of the TRR and the sparse 

population and no industry, there is little expectation 

hazardous materials would be transported. In the 

event the TRR should decide to transport these types 

of materials, it would undertake the plans and 

procedures required by state and federal laws to 

insure their safe handling and storage including 

training of employees. The TRR would operate in full 

compliance with Hazardous Materials Transportation 

Act (49 U.S.C. 1080 et seq.), governing regulations 

and rail industry guidelines for the transportation of 

hazardous materials. It is not anticipated these 

materials would cause any impact to regional 

landfills or exposure to the surrounding environment.
CHAPTER 4

Solid and Hazardous Waste

4-234

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG

Management)

Impacts from Alternative A would be similar to the 

impacts described in the previous Impacts From 

Management Common to All Alternatives section. 

The solid and hazardous waste generated during 

CBNG exploration, production and abandonment 

would be similar to conventional oil and gas. The 

drilling muds would be of lesser quantity because of 

the shallow drilling depths for CBNG wells 

compared to conventional oil and gas.

Crow Reservation

There are no CBNG developments anticipated on 

tribal Lands under this alternative and therefore no 

impacts are expected. Furthermore, there would be no 

impacts on the reservation from the use of solid and 

hazardous materials on off-reservation CBNG

operations. 

Northern Cheyenne Reservation

There would be no impacts on the Northern 

Cheyenne Reservation from solid or hazardous 

material use on off-reservation CBNG developments. 

Conclusion

The cumulative impacts of this alternative would 

include the solid and hazardous waste generated from 

conventional oil and gas, surface mining activities

and CBNG development. These other activities 

would result in increased production of both solid 

and hazardous waste that occur as part of general 

operation activities. Mitigation would include the 

disposal of all wastes in accordance with applicable 

federal, state and local regulations. 

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

The impacts from this alternative would be similar to 

the impacts under Alternative A. However, CBNG

development would result in larger quantities of solid 

and hazardous waste production.

Crow Reservation

There are no tribal sponsored CBNG developments 

anticipated on the reservation under this alternative; 

however, private lands on the reservation could have 

private CBNG developments. These small 

developments are expected to generate solid and 

hazardous wastes in the same proportions as their offreservation counterparts. These wastes will need to 

be disposed of in accordance with applicable tribal

and EPA regulations.

There would be no impacts on the reservation from 

the use of solid and hazardous materials on offreservation CBNG operations. 

Northern Cheyenne Reservation

There would be no impacts on the Northern 

Cheyenne Reservation from solid or hazardous 

material use on off-reservation CBNG developments. 

Conclusion

The cumulative impacts from this alternative would 

be similar to Alternative A. However, the increased 

scale of CBNG development, including the potential 

development of CBNG on the Crow and Northern 

Cheyenne reservations and USFS lands, would 

increase the volume of solid and hazardous waste 

generated. The increased volume of solid and 

hazardous wastes would result in local landfills 

reaching capacity sooner, which would generate the 

need for the construction of new landfills that would 

further disturb lands. The additional trucks used for 

hauling waste would increase traffic and air 

emissions.

Wastes generated on the reservations from tribal

development would need to be disposed of following 

EPA regulations and tribal laws, if any. This may 

necessitate the construction of a non-hazardous 

landfill for the acceptance of solid wastes from the 

RFFA estimate of 4,000 wells per reservation.

Alternative C—Emphasize CBNG

Development

The impacts under Alternative C would be the same 

as for Alternative B.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

The impacts under Alternative D would be the same 

as for Alternative B.
CHAPTER 4

Solid and Hazardous Waste

4-235

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

The impacts under Alternative E would be the same 

as for Alternative B.

Alternative F—Phased Development 

Multiple Screens (High Range)

The impacts under Alternative F would be similar to 

those described for Alternative B, however local 

landfills would receive solid and hazardous wastes at 

a reduced pace resulting in the capacity of the 

landfills to extend further. Construction of new 

landfills would also be delayed. Traffic and air 

emissions from trucks hauling CBNG generated 

wastes would be reduced.

Alternative G—Phased Development 

Multiple Screens (Low Range)

The impacts under Alternative G would be similar to 

those described for Alternative F but reduced by 

approximately 65 percent based on the fewer number 

of APDs predicted to be issued. Under Alternative G, 

the annual cumulative limit placed on federal APDs 

approved by BLM would be set at five percent (323

APDs) of the low-range number of state, private and

federal CBNG APDs (6,470) predicted to be 

approved in the RMP areas (as identified in the 

Reasonably Foreseeable Development scenario in the 

Statewide document).

Alternative H—Preferred Alternative - 

Multiple Screens

Typical solid waste refuse would be generated by oil 

and gas drilling operations and can be disposed of in 

local landfills. The largest volume of waste generated 

from drilling activities would be from the drilling 

mud and cuttings generated. These drilling wastes 

would be exempt from RCRA and are considered 

non-hazardous. Drilling mud containing less than 

15,000 mg/l TDS can be disposed of on-site with the 

landowner’s permission. The amount of waste 

generated should not overwhelm the landfills in the 

area. Other impacts would result from spills of waste 

during maintenance activities, including waste oil 

from generators, paint waste from construction 

activities and other solid wastes from construction 

activities. Impacts would also occur from the use of 

pesticides and herbicides during access and 

construction activities.

The solid and hazardous waste generated during 

CBNG exploration, production and abandonment 

would be similar to conventional oil and gas. The 

drilling muds would be of lesser quantity because of 

the shallow drilling depths for CBNG wells 

compared to conventional oil and gas. However, 

CBNG development would result in larger quantities 

of solid and hazardous waste production due to the 

number of wells predicted.

Crow Reservation

The tribal sponsored CBNG developments 

anticipated on the reservation under this alternative 

coupled with the private lands on the reservation 

would generate solid and hazardous wastes in the 

same proportions as their off-reservation 

counterparts. These wastes will need to be disposed 

of in accordance with applicable tribal and EPA 

regulations. There would be no impacts on the 

reservation from the use of solid and hazardous 

materials on off-reservation CBNG operations. 

Northern Cheyenne Reservation

There would be no impacts on the Northern 

Cheyenne Reservation from solid or hazardous 

material use on off-reservation CBNG developments. 

It is not anticipated the Northern Cheyenne would 

develop any CBNG wells on the reservation for the 

foreseeable future.

Conclusion

The cumulative impacts from this alternative would 

result in drilling wastes and construction debris being 

generated as previously described. However, the 

increased scale of CBNG development, including the 

potential development of CBNG on the Crow and 

Northern Cheyenne reservations and USFS lands, 

would increase the volume of solid and hazardous 

waste generated. The increased volume of solid and 

hazardous wastes would result in local landfills 

reaching capacity sooner than originally planned. 

Eventually new landfills would need to be 

constructed to manage the county and tribal wastes as 

typical domestic and commercial waste generation 

will continue. These new landfills would disturb 

lands but are anticipated, in long-term plans. 

The Tongue River Railroad plans to principally 

transport coal; any potentially hazardous chemicals 

and materials would only be those associated with 

operation of the railroad as a coal transporter. 

Petrochemicals, such as diesel fuel and lubricants, 

would be the primary materials involved in operating 

such a train. It is not anticipated these materials 
CHAPTER 4

Solid and Hazardous Waste

4-236

would cause any impact to regional landfills or 

exposure to the surrounding environment. 

Wastes generated on the reservations from tribal

development would need to be disposed of following 

EPA regulations and tribal laws. This may necessitate 

the construction of a non-hazardous landfill for the 

acceptance of solid wastes from the RFFA estimate 

of 4,000 wells per reservation.
CHAPTER 4

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4-237

Vegetation

Vegetation

Acreages by land classification overlaying coal beds: 

 - Grasslands, 3.55 million (2.56 million in RMP areas)

 - Shrublands 1.8 million, (1.66 million in RMP areas)

 - Forests, 1.36 million (1.29 million in RMP areas)

 - Riparian Areas, 378,000 (268,000 in RMP areas)

 - Barren Lands, 372,000 (297,000 in RMP areas)

87,400 acres overlaying coal beds currently contain non-native 

plants and noxious weeds (37,000 acres in the Planning Area).

Alternative A

No Action (Existing CBNG Management)

• 1,142 acres of native habitat would be impacted under this 

Alternative, more than half (580 acres) in grasslands. 

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• 55,400 acres of native habitat could be impacted under 

this Alternative, with 21,450 acres in grasslands. 

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Alternative C

Emphasize CBNG Development

• 70,000 acres of native habitat could be impacted under 

this Alternative, with 27,300 acres in grasslands. 

• If SAR values exceed 10 in water, riparian vegetation 

would be impacted, affecting as many as 3,535 acres of 

riparian habitat.

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• 55,400 acres of native habitat could be impacted under 

this Alternative, with 21,450 acres in grasslands. 

• Hydrology changes may affect as much as 2,776 acres of 

riparian habitat due to increased stream flow.

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Impacts would be similar to those for Alternative D, 

however no riparian habitat would be affected.

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Alternative F

Phased Development Multiple Screens (High Range)

• Impacts would be similar to those for Alternative B.

• Resource impacts from proposed development projects 

would be evaluated on a watershed-level basis. 

• Annual and watershed-based limits on federal CBNG 

development would result in a different spatial and 

temporal distribution of impacts than the other 

development alternatives.

• Watershed-based analysis would limit the amount of 

disturbed habitat on BLM-administered surface or on 

private surface overlying federal minerals within each 4th 

Order watershed, based on the potential to affect species 

of special concern from habitat fragmentation.

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Alternative G

Phased Development Multiple Screens (Low Range)

• Impacts would be similar to Alternative F but the land 

disturbance area would be 65 percent less.

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Alternative H

Preferred Alternative - Multiple Screens

• Impacts would be similar to those for Alternative B.

• Resource impacts from proposed development projects 

would be evaluated on a watershed-level basis. 

• Use of resource screens and watershed-based limits on 

federal CBNG development would result in a spatial and 

temporal distribution of impacts similar to Alternative F. 

• Watershed-based analysis would limit the amount of 

disturbed habitat on BLM-administered surface or on 

private surface overlying federal minerals within each 4th 

Order watershed, based on the potential to affect species 

of special concern from habitat fragmentation.

• No federal threatened or endangered plant species are 

known to occur within the FSEIS Planning Area. 

Assumptions

The Miles City BLM Seeding Policy, dated 

October 27, 1999 (BLM 1999c), lists guidelines for 

seeding practices by typical Montana soil types; it is 

assumed this policy will be implemented where 

appropriate. Recommended species are identified for 

quick coverage of disturbed soils, to discourage 

invasion of noxious weeds and to attenuate soil 

erosion. Reclamation work will be considered 

complete when the disturbed area is stabilized, soil 

erosion is controlled and at least 60 percent of the 

disturbed surface is covered with the prescribed 

vegetation.

Under all alternatives, most riparian areas and certain 

wildlife habitats (see the Wildlife section) are protected 

from direct impact under current stipulations on BLM-
CHAPTER 4

Vegetation

4-238

administered surface that restrict surface occupancy 

but not road crossings (BLM 1994).

Although, no federal threatened or endangered plant 

species are known to occur in the Planning Area, 

surveys to confirm the absence of federally listed 

species would occur on BLM-administered surface or 

minerals. The APD requires that BLM determine if the 

proposed development plan would affect any species 

listed as threatened or endangered.

Formal consultation with the FWS would occur for 

site-specific federal CBNG projects developed under 

this EIS if a federally listed threatened and endangered 

(T&E) species or candidate or proposed species may 

be affected. Section 7(a) of the Endangered Species 

Act (ESA) requires that federal actions “are not likely 

to jeopardize the continued existence of any 

endangered or threatened species or result in the 

destruction or undesirable modification of its habitat.” 

BLM policy for proposed and candidate species is to 

avoid actions that would jeopardize a species and 

require formal listing under the ESA.

Special management attention is given by state and 

federal agencies to state and BLM Species of Concern. 

Agencies approve actions to avoid areas that would 

jeopardize a species and thereby require federal 

protection in the future. 

The MBOGC environmental review includes an 

assessment of potential impacts to vegetation during 

construction and drilling operations. MBOGC policies 

require the operators to minimize the size of drilling 

pads and require complete restoration of the area once 

operations are complete (Administrative Rules of 

Montana [ARM] 36.22). Mitigation plans are included 

with the environmental review to notify operators of 

requirements prior to construction.

For federal actions, FWS is required to provide

consultation or provide comments to federal agencies

if the potential for taking occurs. They do not have this 

same requirement for state agencies. Even if a state 

agency requests a consultation, the FWS does not have 

the authority to provide it. If a state or private CBNG 

project triggers a federally related action, the FWS

would need to be consulted for federally protected 

species, by the federal agency.

The FWS would be consulted under Section 10 of the 

ESA if a federally related action is triggered.

On BLM-administered surfaces, where specific 

stipulations do not exist or do not currently apply, 

there is a presumption that impacts on T&E plant 

species would be avoided through development and 

observation of specific conservation measures 

developed through consultation with FWS intended to 

avoid impacts on T&E species as required under the 

ESA.

Impacts on T&E plants on non-federal lands are less 

likely to be avoided through conservation measures 

because they are not protected.

Species of concern on all lands would likely receive a 

relatively high degree of protection at a regional scale 

because federal and state agencies are committed to 

avoiding measures that would require listing protection 

under ESA. However, this would likely not protect all 

individuals or perhaps some populations within the 

region.

BLM field clearances and other required preexploration activities developed through this EIS 

process and which are intended to identify site-specific 

occurrence of T&E species, would be conducted as 

specified, leading to knowledge of specific resources 

and implementation of appropriate avoidance actions 

and conservation measures discussed above. 

Federal and state agency monitoring of exploration, 

development and production activities are assumed to 

be adequate to ensure all lease conditions and ESA 

requirements are followed.

Preventing the spread of noxious weeds is easier, more 

successful and less costly and time-consuming than 

reclamation or mitigation. Stipulations for current 

exploration authorizations within the Billings and 

Powder River RMP areas cover weed management and 

riparian/wetland management (BLM 1992). Under 

these stipulations, all categories of noxious weeds must 

be managed. 

Stipulations and options for containment of noxious 

weeds on state lands are listed in the Minerals 

Appendix, Table MIN-5.

The BLM has co-developed an action plan for weed 

containment and eradication practices that will be 

implemented for all alternatives (BLM 1996). Pertinent 

sections of Appendix 3 from that document are 

reproduced in Table 4-63. The action plan applies to 

the State of Montana’s list of weed species of concern 

(see Table VEG-7, Vegetation Appendix). This list 

includes species that are considered to be highly 

invasive and disruptive to natural systems. It is 

assumed that these weed-prevention activities will be 

required for CBNG exploratory and production sites, 

roadways, pipelines, utility corridors and other 

disturbed sites on BLM-administered surface except as 

specifically noted for some of the alternatives. 
CHAPTER 4

Vegetation

4-239

TABLE 4-63

EXAMPLE: PARTIAL BLM DISTRICT-WIDE WEED PREVENTION SCHEDULE

Prevention Activity When Who Is Responsible

Clean off-road equipment with powerwash or high-pressure 

to remove all mud, dirt and plant parts before moving into 

relatively weed-free areas.

All Year Equipment Operators; Fire Crew

Re-establish vegetation on all disturbed soil from 

construction, reconstruction and maintenance activities.

Spring/Fall Project Proponent

Inspect gravel pits and fill sources to identify weed-free 

sources. Gravel and fill to be used in relatively weed-free 

areas must come from weed-free sources.

Spring/Summer Surface Protection Specialist; 

Equipment Operator

Retain bonds (for mineral activity) for weed control until the 

site is returned to desired vegetative conditions.

All Year Mineral Specialist

Include weed-risk considerations for environmental analysis 

for habitat improvement projects.

All Year Wildlife Biologist

Provide weed identification training for field-going 

employees and managers.

Winter/Summer Weed Coordinator

Distribute public information/brochures. Spring/Summer Public Affairs Officer

Include weed risk factors and weed prevention considerations 

in Resource Advisor (Environmental Specialist) duties on all 

Incident Overhead Teams and Fire Rehabilitation Teams.

Summer Resource Advisor

Note: Revised from BLM 1996.

Wetlands are legally protected by Section 404 of the 

Clean Water Act. Therefore, all such wetlands must be 

surveyed and delineated before any drilling can take 

place. If wetlands will be impacted by proposed 

drilling or road alignments, they must be avoided or 

mitigation measures must be developed to compensate 

for impact. This compensation may include the 

development of replacement wetlands. In some 

instances, Nationwide 404 Permits may apply to 

CBNG projects. Applicable permits include Utility 

Line Activities and Linear Transportation Crossings. 

The producers must meet all terms and conditions of 

the Nationwide 404 Permit for it to apply.

On private lands, it is assumed that the private 

landowner will negotiate with the producer before 

exploration and development and come to an 

agreement as to what measures the producer will 

instigate for weed control, site restoration and as to 

what criteria constitutes successful site restoration and 

proper weed control.

Impacts From Management Common 

to All Alternatives

Construction of facilities and roads would cause the 

primary effects on vegetation. For a developed well 

site, about 40 percent of the original drill site would 

remain disturbed for the life of the well (20 years). 

However, unsuccessful exploratory sites would be 

reclaimed. Reclamation generally includes spreading 

topsoil and reseeding according to the landowner’s 

request (private land) or the BLM Seeding Policy

(BLM 1999c). The BLM Seeding Policy and site 

restoration stipulations do not extend beyond the 

borders of their lands. Therefore, it is essential that 

private landholders negotiate with the producer prior to 

exploration and development on private lands and 

come to an agreement as to what measures the 

producer must instigate for weed control and site 

restoration. This includes what criteria will be used to 

assess adequate site restoration and proper weed 

control. Pre-development agreements are the 

responsibility of the landowner.
CHAPTER 4

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4-240

Small areas of vegetation would be lost to roads and 

drill sites for each well. Dust and vehicle emissions 

could reduce growth of vegetation adjacent to roads 

and drill sites. If disturbed areas are prepared and 

seeded properly, reclamation may further reduce the 

effects of dust. The effects of drilling on vegetation 

would be of particular concern under the following 

circumstances: 

• When drill sites or roads are proposed within or 

cross riparian areas, wooded drainages, or 

wetlands

• Where drill sites or roads would cause 

sedimentation or channel down-cutting in riparian 

areas

• When drill sites or roads would be in areas that 

contain populations of special status plants

• Where operations could spread or encourage the 

growth of weeds

• In case of reserve pit leakage

• In the event of blowouts or wildfire

Drilling sometimes may occur in or near areas that 

support riparian vegetation or special status plants. If 

located in or at the head of drainages, drill sites and 

access roads can add sediment to streams and 

wetlands. Channel degradation can also occur. Heavy 

sediment loads or severe degradation would affect 

riparian vegetation. Roads and facilities are supposed

to avoid sensitive areas “to the extent practicable.” 

Therefore many, but not all, sensitive areas such as 

riparian areas and wetlands would be avoided.

Soil disturbance associated with drilling can cause 

weeds to spread. Of even greater concern is the longdistance transport of certain weed species by drilling 

equipment and vehicles. Weed spread is reduced if 

disturbed areas are re-vegetated during the season of 

disturbance or the next growing season as 

recommended (Table 4-63). All well drilling 

operations are covered by the County Noxious Weed 

Control Act, which holds landowners responsible for 

weed control. The contribution of oil and gas drilling 

to weed spread is comparable to other types of 

construction. 

Because of the legal restrictions placed on the harm or 

take of federally listed species, direct impacts to these 

listed species would not occur on federal land. Indirect 

impacts to federally listed species such as habitat 

destruction will be addressed on a species-by-species 

basis. Federally listed plant species on non-federal land 

ownership may be impacted through conventional oil 

and gas activities because threatened and endangered 

plants on private lands are generally not surveyed and 

their presence may not be known.

Mitigation

Site clearance surveys would be conducted prior to 

disturbance. Where necessary, operator plans would be 

adjusted as appropriate to avoid impacts to federally 

listed species.

Review of Montana Natural Heritage Program data on 

a case-by-case basis for TLMD Montana Oil and Gas

lease sale may indicate areas of plant locations on state 

lands. A vegetation survey stipulation is used on the 

lease. For site-specific proposals, the TLMD field staff 

may consult with DNRC biologists and Montana-NHP 

botanists as needed. The TLMD stipulation (see Table 

MIN-5), reads as follows: “Plant species of concern 

have been identified on or near this tract. A vegetation 

survey in areas of proposed activity will be required 

prior to disturbance. Identified rare plant species will 

be avoided, unless authorized by the TLMD.”

Conclusions

There would be no impact on federal land to federally 

listed species. There may be impacts to federally listed 

plants on non-federal land and to other species of 

concern.

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

Previous authorizations have allowed selected CBNG

exploration in the Powder River and Billings RMP 

areas as well as selected well development and 

exploration on state lands. 

Disturbance to vegetation is of concern because 

wildlife habitat and livestock production capabilities 

may be diminished or lost over the long-term through 

direct loss of vegetation (including direct loss of both 

plant communities and specific plant species). Indirect 

impacts, such as noxious weed invasion erosion could 

result in loss of desirable vegetation. Under the No 

Action Alternative, only riparian habitat types and 

certain wildlife habitats (see Wildlife section) are 

protected under current stipulations (BLM 1995).
CHAPTER 4

Vegetation

4-241

Direct impacts on vegetation would occur during landdisturbing activities associated with installation of 

exploratory or development CBNG wells that remove 

vegetation to construct a facility (e.g., roads, drilling 

pads, mud pits). All direct impacts from exploratory 

wells are for the life of the well, then rehabilitated. 

Both temporary and permanent impacts would occur 

with installation of development wells. 

DNRC, TLMD uses buffer stipulations and use of the 

no-surface-occupancy of navigable riverbeds and 

related acreage stipulation on its oil and gas leases on a 

case-by-case basis for protection of riparian habitat. 

Table 4-64 summarizes the acreage that could be 

potentially impacted in the two RMP areas and the 

three counties under state-permitting jurisdiction. 

Vegetation types to be potentially impacted were 

determined based on the extent of each vegetation type 

overlying coal beds. Impacts to specific vegetation 

types were assigned in proportion to their total acreage 

within an ownership (see Table 4-64). For example, 

there are 1,537,000 acres of grassland in the Powder 

River RMP area or 40 percent of the total area. 

Assuming that 200 acres would be permanently 

disturbed in the Powder River RMP area, 80 acres 

(40 percent) of permanent, direct impacts would be 

expected to occur in grassland. If natural communities 

from Table 4-65 are considered, grasslands would be 

expected to experience the largest permanent loss

(580 acres), based on occurrence. Shrubland would be 

the next most permanently impacted habitat

(174 acres), followed by forest land (114 acres), barren 

land (46 acres) and riparian habitat (56 acres). Of the

56 permanently impacted riparian acres, 20 are on 

BLM-administered surface and most are protected by 

stipulation

during exploration. Indirect impacts may be as 

important as direct impacts for plants and habitats. As 

noted earlier, indirect impacts would include the 

effects of erosion, changes in wildlife and livestock 

distribution, riparian community changes and the 

spread of noxious weeds.

Erosion from roads and drilling sites can indirectly 

affect vegetation from high runoff velocities scouring 

the plants from the site or by sediment burying the 

plants. The extent of this potential impact would be 

determined by the effectiveness of erosion-control 

measures and the level of enforcement of stormwater 

management plans. Plant community impacts would be 

in the same proportions as discussed under direct 

impacts. The basis of this analysis is formed from the 

assumption that installation of erosion-control 

procedures and effective enforcement of stormwater 

management plans would occur. Implementation of 

erosion-control measures and stormwater management 

plans would result in no long-term impacts from 

erosion. Short-term impacts are still likely to occur 

from thunderstorms during first few years and from 20 

years of active roadbeds.

A total of 250 acres may be reclaimed following 

temporary disturbance at state-permitted wells. Failure 

to adequately restore these acres to pre-disturbance 

conditions would result in a loss of native habitat. 

Typical seeding mixes only include herbaceous 

species. Therefore, after reclamation and reseeding, 

there would be a change in the vegetative composition 

of the disturbed areas.. If reseeding is successful, it 

would potentially reduce noxious weed invasion, 

erosion and dust through restoration of plant cover.

TABLE 4-64 

AMOUNT OF ACREAGE WITH UNDERLYING COAL BEDS IN EACH HABITAT TYPE

(BY RMP AREA AND STATE LAND)1

Area Grassland Shrubland Forest Land

Barren 

Land Riparian2

Agricultural or Other 

Land Not Included as 

Native Vegetation 

Powder River RMP area 1,537,000

(40%)

920,000

(24%)

908,000

(23%)

210,000

(5%)

170,000

(4%)

138,000 

(4%)

Billings RMP area 1,022,000

(40%)

737,000

(29%)

377,000

(15%)

87,000

(3%)

98,000

(4%)

207,000

(8%)

MBOGC-regulated land 990,000

(56%)

152,000

(9%)

89,000

(5%)

75,000

(4%)

93,000 

(5%)

359,000

(20%)

1

Figure in parentheses indicates percentage of total acreage within the RMP area and MBOGC-regulated land. 

2

These acres are exempt from CBNG development as a result of stipulations that omit this type from consideration for CBNG exploration 

and development; they may be affected by water pollution and increased salinity.
CHAPTER 4

Vegetation

Internal Working Document 4-242

CBNG exploration activities could result in the 

recruitment of noxious weeds by disturbing present 

vegetative cover, compacting soil, exposing mineral 

soil to seed fall and aiding the migration of seeds 

through movement of vehicles and drilling equipment 

from site to site. Noxious weeds can indirectly impact 

native vegetation by out-competing native plants for 

scarce nutrient, light and water resources, thereby 

displacing the native species. Sites with the greatest 

potential for noxious weed invasion, erosion, or 

difficulty in restoring to pre-disturbance vegetation are 

generally sites with pre-existing weed problems or 

drier sites, such as those designated as barren land. 

Noxious weeds introduced into a forest environment 

would be very difficult to control because of access

restrictions when weeds spread into deep drainages and 

timbered hills where chemical control would be 

difficult. Control of noxious weeds is addressed under 

current BLM stipulations or state law. The increase in 

the number and potential for spread of noxious weeds 

with disturbance is an important consideration even at 

the current level of exploration and development. This 

concern is related to other indirect impacts, such as 

lack of successful reclamation and erosion. 

Roads are considered a major contributing factor to the 

continuing spread of exotic plant species. Improved 

roads can provide the means by which adjacent natural 

habitats are converted to ecosystems highly vulnerable 

to invasion by exotic plants. Various factors influence 

the susceptibility of communities farther from roads 

versus those along roads, including dominant 

vegetation, soil moisture, nutrient levels, soil depth, 

disturbance and topography. Plant communities 

appearing most vulnerable are those that are both 

physically conducive to invasion (e.g., having deep or 

fertile soils) and disturbed (Gelbard and Belnap 2003).

Species of concern include federally listed T&E and

candidate species; Montana species of concern; BLM 

species of concern, and Montana Natural Heritage 

Program species of concern. For the state, this 

document addresses only those listed as category S1, 

which are species of extreme rarity or species for 

which some factor of its biology makes it especially 

vulnerable to extinction. The Vegetation Appendix, 

Table VEG-6 describes and lists all special-status 

species.

As discussed in the Species of Concern section of 

Chapter 3 in this EIS, there are no known federally 

listed threatened or endangered plant species in the 

Planning Area. In accordance with the ESA, any 

identified federally listed species and their habitat must 

be protected from possible impact by oil and gas and 

CBNG development on federal land, but not on state or 

private land. Additionally, 69 species are classified as 

“species of special concern” by the Montana BLM and 

the Montana Natural Heritage program. By policy, 

BLM management cannot impact these species in a 

way that may cause further declines in the species’ 

population status. 

Crow Reservation

CBNG development on the Crow Reservation is 

expected to be very limited. To the extent that it does 

occur, impacts to plant communities and natural 

vegetation would be similar to those described for 

private lands and would occur on a much smaller scale 

than on BLM or State lands.

TABLE 4-65

ACREAGE POTENTIALLY IMPACTED IN EACH HABITAT TYPE FOR ALTERNATIVE A

(BY RMP AREA AND STATE-PERMITTED LAND1) 

Area

Grassland Shrubland Forest Land Barren Land Riparian Other Areas Permanent Temporary Permanent Temporary Permanent Temporary Permanent Temporary Permanent Temporary Permanent Temporary

Powder River RMP 80 0 48 0 46 0 10 0 8 0 8 

Billings RMP 80 0 58 0 30 0 6 0 8 0 16

MBOGC-regulated land 420 140 68 23 38 13 30 10 38 13 150 50

Total* 580 140 174 23 114 13 46 10 54 13 174 50

*These estimates were arrived at using GIS data. Sweet Grass and Carter counties did not have enough bituminous coal beds to show up 

on those layers, therefore CBNG well data for those two counties are not included in these estimates. The total acres of impact using GIS 

data are 1,391 acres. Total real impacts for all counties are estimated to be 1,488 acres.

1 MBOGC regulated
CHAPTER 4

Vegetation

4-243

Northern Cheyenne Reservation

CBNG development on the Northern Cheyenne 

Reservation is expected to be very limited. A study of 

methane gas development on Northern Cheyenne lands 

concluded that it would be uneconomical (Little 

Coyote 2001; Herco-Hampton 1989). To the extent 

development does occur, impacts to plant communities 

and natural vegetation would be similar to those 

described for private lands and would occur on a much 

smaller scale than on BLM-administered or State 

lands.

State Species of Concern

Direct and indirect impacts on other species of concern 

would be expected to some degree.

Conclusions

Up to 1,105 acres of native vegetation (excluding up to 

20 riparian acres on BLM-administered surface) would 

be lost through CBNG exploration activities and an 

additional 250 acres would be temporarily disturbed. 

Unspecified impacts to native vegetation through 

livestock grazing would occur if displaced animals 

concentrate in certain areas. Shrub, forested and barren 

lands would not be adequately restored using the 

existing recommended seeding mix, which reseeds 

only grasses. For all habitats, some reclamation efforts 

may fail. Strict adherence to reclamation policies 

would result in no impact to vegetation from noxious 

weed infestations. However, these guidelines and 

regulations have been in place for many years and 

weeds continue to spread across central and eastern 

Montana. Therefore, some further infestations of 

noxious weeds would be expected. User-created roads 

would result in additional loss of vegetation and 

increased potential spread of noxious weeds (USDI 

and USDA 2001). No impacts on the Ute ladies’-tress 

would be expected.

Cumulative Impacts

Cumulative impacts may occur from coal mining 

operations. Coal mining occurs within the same area 

covered by this EIS. Vegetation will be destroyed 

within the disturbed area of a coal mine. As the mine 

area is reclaimed, topsoil is redeposited and reseeded 

to reestablish vegetation. Reseeding during 

reclamation activities will generally result in an 

increase in grasslands with less plant diversity than 

was present under pre-mining conditions. 

Construction of the proposed Tongue River Railroad 

would result in the removal or disturbance of 328 to 

456 acres of vegetation within the ROW. Vegetation 

within each of the three ROWs is a mixture of 

pine/juniper, grassland/sagebrush, agricultural, 

deciduous tree/shrub and breaks habitat. Revegetation 

would reduce the area of permanent disturbance (STB 

2004).

During operations, principal impacts to vegetation 

would be caused by the use of herbicides to control 

weeds, range fires and possibly coal dust. The use of 

herbicides could damage native plant species and could 

increase the likelihood of range fires due to the 

presence of dead and dying vegetation. Local ranchers 

have expressed concern regarding the propagation of 

noxious weeds by passing trains, as well as the 

potential for railroad-caused range fires. In addition to 

being a fire hazard, weeds can reduce crop production 

(Surface Transportation Board 2004). 

About 92 percent of the coal volume located in the 

Powder River basin occurs within Wyoming (Ellis et 

al. 1999b) and as many as 50,000 CBNG wells may be 

developed in the Wyoming portion of the basin. The 

direct and indirect effects of Wyoming CBNG 

development would far surpass the effects of CBNG 

development in Montana under Alternative A because

of so many wells. Some rivers entering Montana from 

Wyoming would be expected to have higher flows, 

resulting in potential erosion of wetland and riparian 

communities and habitat degradation.

ESA provisions applied to other projects should avoid 

cumulative impacts to T&E wildlife species when 

considered in conjunction with CBNG exploration and 

development. 

Alternative B—Emphasize Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

As listed under Alternative A, four habitat types 

(grassland, shrubland, forest land and barren land) will 

be affected in varying amounts depending on the 

alternative and the amount of habitat with underlying 

coal beds. Well development is estimated at 18,300 

wells in the RFD, but only 16,470 of these will be 

production wells. If these wells are distributed evenly 

over habitats by the proportion of habitats with 

bituminous coal beds, a total of approximately 55,360 

acres would be directly impacted by production wells 

and dry hole drilling. Approximately 48,864 acres 

would occur on land with native vegetation: 21,446 

acres of grassland vegetation, 13,214 acres of 

shrubland, 11,680 acres of forest land and 2,523 acres 

of barren land could be potentially impacted, if wells 

were distributed in proportion to the amount of acres in 

each habitat type. Direct impacts to riparian areas are 

similar to Alternative A.

Table 4-66 estimates the acres of direct impact for each 

action alternative based on information in Chapter 2. 
CHAPTER 4

Vegetation

4-244

TABLE 4-66

ACRES OF LAND AND LENGTH OF ROADS AND UTILITY CORRIDORS DIRECTLY IMPACTED BY 

NEW CBNG CONSTRUCTION 

Alternative

B and D C E F and H G 

Area disturbed per well1, 2 3.25 acres 4.14 acres 4.14 acres 3.25 acres 3.25 acres

Length of roads per well2 0.237 miles 0.365 miles 0.365 miles 0.237 miles 0.237 miles

Length of utility corridor per well3 0.734 miles 1.13 miles 1.13 miles 0.734 miles 0.734 miles

Number of wells2 18,300 18,300 18,300 18,225 6,470

Total area directly disturbed3,4 55,360 acres 70,015 acres 73,860 acres 59,045 acres 21,035 acres

Length of CBNG roads per square mile2, 

4

2.9 to 8.8 miles 3.9 to 11.9 

miles

3.9 to 11.9 

miles

2.9 to 8.8 miles 2.9 to 8.8 miles

Total length of CBNG roads1, 2 6,680 miles 9,018 miles 9,018 miles 6,662 miles 2,375 miles

Length of pipeline and utility corridors 

per square mile3,5

9.04 to 27.12 

miles

12.2 to 36.61 

miles

12.2 to 36.61 

miles

9.04 to 27.12 

miles

9.04 to 27.12 

miles

Total length of pipeline and utility 

corridors1, 3

20,679 miles 27,917 miles 27,917 miles 20,623 miles 7,345 miles

1

The land area disturbed and the length of roads and corridors would be 27 percent greater for Alternatives C and E than for Alternatives B, D, F and H 

because transportation corridors and the use of existing disturbed lands would not be required for roads and utilities under Alternatives C and E. 

2 Short-Term. 

3 Long-Term. 

4 Area of direct disturbance for Alternative E is greater than Alternative C to account for the 3,700 wells requiring water basin impoundment structures. 

Alternatives F, G and H also account for water basin impoundment structures.

5

Length of roads, pipelines and utility corridors per square mile covers the range of 8 to 24 wells per square mile of land overlying 1 to 3 coal seams, 

respectively. At an average of 8 wells per square mile, 2,287 square miles (2281 square miles for Alternative F and H, 813 for Alternative G) would be 

impacted by intensive CBNG development. At 24 wells per square mile, 762 square miles (760 square miles for Alternative F, 271 for Alternative G)

would be impacted by intensive CBNG development. Additional wildlife habitat surrounding well fields would be indirectly impacted by human 

activities and presence.

Direct vegetation loss by habitat type is assumed to 

be proportional to the relative amount of each habitat 

type shown in Table 4-64. 

As discussed in the Wildlife section, water production 

and roads can alter the distribution of wildlife and 

livestock. As wildlife or livestock use is concentrated 

due to those factors, plant communities can be altered 

through overgrazing. Overgrazing tends to favor 

establishment and reproduction of annual and 

invasive plant species. These species tend to displace 

native plant assemblages. To the extent grazing 

animals concentrate in smaller areas, plant 

communities would change to less diverse, 

introduced plant communities. Most county weed 

control efforts focus on herbicide spraying, which 

reduces plant diversity even more.

Indirect effects include changes in wildlife and 

livestock distribution patterns as a result of 

machinery disturbance or removal of habitat. 

When disturbance removes vegetative cover from 

soil, it is open to erosion from wind and water. 

Erosion from roads and drilling sites can indirectly 

affect vegetation from high runoff velocities scouring 

plants from the site or by sediment burying the 

plants. The extent of this potential impact would be 

determined by the effectiveness of erosion-control 

measures and the stormwater management plans. 

Types of plant community impacts would be in the 

same proportions as discussed above but on a much 

greater scale than for Alternative A. 

Existing hydrology and riparian vegetation would not 

be affected by build-up of salts with this alternative 

because of the use of injection and holding tanks for 

production water. The potential for spreading noxious 

weeds is substantially greater than under 

Alternative A because 20 times as much land would 

be disturbed.
CHAPTER 4

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4-245

Species of Concern-Federally Listed 

Species

Direct impacts to federally protected species are 

prohibited by law and would not occur under 

Alternative B, which is the same as under Alternative 

A, because none have been reported in the Planning 

Area. 

The potential for direct and indirect impacts on other 

species of concern would be much greater under this 

alternative because of the much larger amount of 

habitat that will be disturbed or lost with the 

increased level of vegetation disturbance associated 

with the greater number of well pads, roads, pipelines

and utility lines. More roadways provide greater 

access and more potential for disturbance of 

protected species.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative B. If there 

were no CBNG development on tribal Lands, then 

there is expected to be minimal, impacts on 

vegetation for the reservation. If there is CBNG 

development on the reservation, then the acres of 

disturbed habitat could be inferred to the reservation 

using the same approach used in this section. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described in general for this 

Alternative.

Conclusions

The impacts of CBNG development under 

Alternative B would be substantially greater than 

under Alternative A because 20 times as many wells 

would be developed and 20 times as much area 

would be disturbed. 

Reclamation after well abandonment on 44,000 acres 

may revegetate well sites and roads, but not 

necessarily restore the sites to previous vegetation or 

habitats, resulting in native habitat loss.

Cumulative Impacts

Cumulative impacts would be the same as described 

for Alternative A except that Montana CBNG 

development impacts would be greater.

Alternative C—Emphasize CBNG

Development 

A total of approximately 70,015 acres would be 

directly impacted. Approximately 62,238 of this 

acreage would be on sites with native vegetation 

cover. Approximately 27,316 acres of grassland 

vegetation, 16,831 acres of shrubland, 14,877 acres 

of forest land and 3,214 acres of barren land could be 

potentially impacted, if wells were distributed in 

proportion to the amount of acres in each habitat 

type. Direct impacts to riparian areas are similar to 

Alternative A. In addition, although no wells will be 

authorized in riparian areas under any alternative, the 

discharge of untreated water from exploration and 

production onto the surface could affect riparian 

vegetation, perhaps as much as 3,535 acres. This is 

the estimated average total acreage of habitat with 

riparian vegetation that is underlain by bituminous 

coal bed (BLM and state). 

Indirect impacts would include the impacts noted 

earlier of noxious weed invasion, erosion and

changes in wildlife and livestock distribution. In 

addition, indirect impacts would include increased 

SAR and salinity levels, which could result in 

riparian community changes and increased erosion 

potential for wetland and riparian communities. 

Alternative C has the greatest potential for erosion 

because of the increased disturbance area with no 

restrictions on corridors for pipelines, utilities and 

roadways and no requirements for directional drilling 

or multiple completions in a single well. The extent 

of erosion would be determined by the effectiveness 

of erosion-control measures and the stormwater 

management plans. This alternative will potentially 

increase the area of disturbance over Alternatives B 

or D by approximately 15,000 acres (Table 4-66). 

This acreage increase will increase the potential for 

erosion.

With discharge of the CBNG water to surface 

drainages and streams, erosion could occur, which 

could damage or destroy instream and streambank 

riparian vegetation (Regele and Stark 2000). The 

erosion could result in increased sediment loads that, 

along with the potential high salinity and sodicity, 

could degrade the stream and impact riparian 

vegetation. Impacts of discharging CBNG waters 

would likely be greatest in intermittent and smaller 

perennial drainages during low-flow periods. 

Releases during low-flow periods of late summer and 

fall would have the greatest potential to impact 

riparian vegetation. This is also the time when this 

vegetation is naturally stressed because of low water. 

The potential for impacts on riparian vegetation 
CHAPTER 4

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exists along drainages and streams throughout the 

CBNG development area.

CBNG groundwater discharge has an SAR capable of 

killing vegetation (Regele and Stark 2000). Plant 

growth is affected in sodic soils due to decreased soil 

permeability, increased pH (which lowers nutrient 

availability) and accumulation of certain elements 

(sodium, boron and molybdenum) at a level toxic to 

plants. Because of the typically low flows of the 

CBNG wells (approximately 5 to 10 gallons per 

minute), it is likely that these SAR impacts would be 

localized in the vicinity of the discharge, unless flow 

were collected from a large number of wells. 

Species of concern have a higher potential for direct 

and indirect impacts compared to Alternative B 

because of more surface disturbance.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative C. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described in general for this 

Alternative.

Conclusion

Reclamation of vegetation after well abandonment 

may revegetate well sites and roads, but not 

necessarily restore the sites to previous vegetation or 

habitats, resulting in native habitat loss. 

Localized increases in salinity and SAR values may 

be the most important aspect of this alternative. 

Salinity can have long-term effects on vegetation, 

including changes in species composition to more 

salt-tolerant species and high concentrations of salt in 

riparian soils. Soil impacts may last long after a given 

project site has been abandoned. Increased SAR 

values may prevent nonhydrophytic reclamation 

vegetation from succeeding. Increased roads result in 

more land being disturbed, more wildlife and 

livestock forage will be removed and more area for 

noxious weed invasion being present.

All species of concern that are not federally protected 

may be impacted by habitat changes caused by 

vegetation removal that are not fully recovered with 

reclamation after well abandonment, by increased 

access through increased roads and/or by changing 

streambed hydrology and increased SAR and salinity 

values in water and soil.

Cumulative Impacts

The types of cumulative impacts are the same as 

discussed under Alternative A. Disturbed habitat 

quantities would be similar to those described in 

Alternative B.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses 

Impacts

Impacts on habitat types under this alternative would 

be the same as Alternative B except for the potential 

for riparian impacts. Although no wells will be 

authorized in riparian areas on BLM-administered 

surface under any alternative, the discharge of water 

from exploration and production onto the surface 

could create riparian areas that will be abandoned and 

could affect the hydrology of current riparian areas, 

perhaps as much as 2,776 acres.

Under this alternative, indirect impacts could include 

the impacts noted earlier of noxious weed invasion, 

erosion and changes in wildlife and livestock 

distribution. In addition, indirect impacts would 

likely include increased water being added to riparian 

systems, which could affect riparian vegetation. 

Reservoirs that are used in this alternative for holding 

treated water could produce problems when they are 

abandoned. Riparian vegetation that developed 

during the operation dies after abandonment and the 

bed of the drying reservoir tends to become infested 

with noxious weeds (Lahti 2001).

Erosion potential may increase under this alternative 

because there are no reclamation requirements for 

roadbeds. This is offset somewhat by the stipulation 

that no slopes greater than 30 percent can be used for 

CBNG construction.

Discharge of water from exploration and production 

onto the surface could affect the hydrology of as 

much as 2,776 acres of current riparian vegetation. 

Species of concern could be impacted as described 

for Alternative B and by discharge of CBNG water.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative D. 
CHAPTER 4

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Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described in general for this 

Alternative.

Conclusions

There is no requirement for road abandonment so 

long-term impacts caused by removal of vegetation 

for roadways is not known, but would occur. 

Stipulations concerning slope of land for potential 

CBNG sites are likely to protect such slopes from 

failure and mass wasting problems. A secondary 

effect is that such areas will remain in their existing 

habitat and plant communities. Reclaimed areas may 

revegetate adequately, but this will not restore the 

sites to previous native vegetation or habitats. There 

is potential for habitat loss because of the lack of 

requirements for roadbed reclamation or for 

abandoned reservoirs. Areas that are not reclaimed 

would represent a permanent loss of native vegetation 

and be subject to noxious weed infestations.

All species of concern that are not federally protected 

may be impacted by habitat changes caused by 

vegetation removal that are not fully recovered with 

reclamation after well abandonment, by increased 

access through user-created roads, or by changing 

streambed hydrology and increased SAR and salinity 

values in water and soil.

Cumulative Impacts

Cumulative impacts from Alternative D would be the 

same type of impacts as described for Alternative A. 

The quantity of disturbed habitat would be the same 

as discussed under Alternative C.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Impacts

The same types of impacts to vegetation and species 

of concern described for Alternative C would occur 

under Alternative E because no additional specific

mitigation measures will be required and because 

transportation corridors will not be required. There 

will be additional impacts in addition to those for 

Alternative C for the 3,700 wells that will have water

basin impoundment structures. This will increase area 

of total impacts to approximately 73,860 acres. Of 

this, approximately 66,457 acres of native vegetation 

will be impacted, 29,168 acres of grassland, 17,972 

acres of shrubland, 15,885 acres of forest land and

3,432 acres of barren land. 

This Alternative would require a Water Management 

Plan for every well exploration APD on a sitespecific basis for management of production water. 

There would be no discharge of produced water, 

either treated or untreated, into the watershed under 

this alternative unless the operator can demonstrate in 

the Water Management Plan how discharge could 

occur without damaging the watershed in accordance 

with water quality laws. Water quality laws will not 

protect riparian vegetation from inundation and other 

changes in the water level as a result of production.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative E. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described in general for this 

Alternative.

Specific mitigation measures proposed by the 

Northern Cheyenne Tribe that will be implemented 

by the BLM are described in the Northern Cheyenne 

Tribe Mitigation Appendix.

Conclusions

Residual impacts would be the same as described for 

Alternative C. All species of concern that are not 

federally protected may be impacted by habitat 

changes caused by vegetation removal that are not 

fully recovered after well abandonment and by 

increased access through increased road densities, 

which may cause greater disturbance and noxious 

weed infestations. 

Cumulative Impacts

The cumulative impacts from Alternative E would be 

the same types of impacts as described for 

Alternative A. The quantity of disturbed habitat 

would be the same as discussed under Alternative C.

Alternative F—Phased Development 

Multiple Screens (High Range)

Impacts

The area of surface disturbance for Alternative F, in 

which vegetation and species of concern could be 

impacted, is expected to be approximately 59,100
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acres, which is slightly higher than Alternative B but

less than Alternative E (Table 4-66). As under 

Alternative E, this alternative would require 

development of PODs in consultation with tribes, 

surface owners and other involved permitting 

agencies. Each of these Project Plans would include a 

site-specific Reclamation Plan, Wildlife Monitoring 

Plan, Surface Use Plan, Noxious Weed Management 

Plan and Water Management Plan. Unlike 

Alternative E, this alternative would use watershedlevel analysis to evaluate resource effects from 

CBNG and other activities occurring within the 

affected watersheds. 

The allowable development in the crucial sage-grouse 

habitat areas would likely be less dense than the typical 

80-acre well-site spacing and if no development were to 

occur in these areas, overall impacts to vegetation would 

be reduced by approximately 12.8 percent. This would 

reduce the amount of disturbed vegetation by 

approximately 7,565 acres. 

Additionally, annual and watershed-specific limits on

the number of federal CBNG wells developed would 

reduce the impacts that would otherwise occur under 

the other development alternatives during the initial 

years of the planning period. The resultant rate of 

development would provide a more even level of 

impacts as most of the predicted state wells are 

developed in the first half of the planning period and 

more of the predicted federal CBNG wells are 

developed in the latter half. Additionally, vegetation 

disturbance may be reduced based on results of the 

watershed-level analysis used to evaluate 

development proposals. Disturbance in individual 

watersheds would be limited to prevent the potential 

for fragmentation of habitat for species of concern. 

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative F. Project 

Plans of Development requiring consultation with 

tribes, resource protection protocols based on 

watershed-level analysis and monitoring of 

development within a 5-mile buffer around the 

Reservation would provide additional opportunities 

for protection of Reservation resources.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation. 

Specific mitigation measures proposed by the 

Northern Cheyenne Tribe that could be implemented 

by the BLM are described in the Northern Cheyenne 

Tribe Mitigation Appendix.

Conclusions

Residual impacts would be similar to Alternative B, 

except that they would occur more evenly during the 

20-year planning period. Site-specific Project Plans 

of Development and watershed-level of analysis 

would likely reduce potential effects to species of 

concern under Alternative F relative to Alternatives B 

through E. 

Cumulative Impacts

The cumulative impacts from Alternative F would

have similar types of impacts as described for 

Alternative B. However, the quantity of disturbed 

habitat would be slightly higher than Alternative B, 

because of additional water basin impoundment 

structures required for Alternative F (Table 4-66). 

However, the timing and location of habitat 

disturbance would vary for this alternative versus 

Alternatives B through E due to the annual and 

watershed-based limits imposed on federal well 

development. 

Alternative G—Phased Development 

Multiple Screens (Low Range) 

Impacts

The area of surface disturbance for Alternative G, in 

which vegetation and species of concern may be 

impacted, is expected to be approximately 21,100 

acres, which is less than Alternative F because the 

number of wells and the resulting area of disturbance 

would be approximately 65 percent less. The types of 

impacts of Alternative G would be similar to 

Alternative F, because both alternatives would use 

watershed-level analysis to evaluate resource effects 

from CBNG and other activities occurring within the 

affected watersheds.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative G. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation. 
CHAPTER 4

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Conclusions

The impacts from Alternative G would be the same 

types of impacts as described for Alternative F, but 

would occur over a 65 percent smaller area.

Cumulative Impacts

The cumulative impacts from Alternative G would be 

the same types of impacts as described for 

Alternative F, but would be less because of the 

smaller affected area.

Alternative H—Preferred Alternative - 

Multiple Screens

Impacts

Alternative H is the BLM’s Preferred Alternative for 

the development of CBNG resources on BLMadministered lands. Alternative H will review CBNG 

proposals against four resource screens. This 

Alternative would also require PODs that include 

mitigation measures. The resource screens would be 

applied to water resources, wildlife, Native American 

concerns and air resources. The screens would be 

implemented with the goal of monitoring impacts and 

developing a decision-making process to control and 

reduce impacts before they become unsustainable. 

Of the four screens only the wildlife and water 

screens would directly affect vegetation. The air 

screen would not affect vegetation, while the Native 

American screen could indirectly affect vegetation on 

Native American lands by addressing discharge of 

groundwater onto surface vegetation and protecting 

Indian Trust Assets. 

The area of surface disturbance for Alternative H, in 

which vegetation and species of concern could be 

impacted, is expected to be approximately 59,100 

acres, which is similar to Alternative F, higher than 

Alternative B, but less than Alternative E. As under 

Alternatives E and F, the PODs would be developed 

in consultation with tribes, surface owners and other 

involved permitting agencies. Each of the PODs 

would include a site-specific Reclamation Plan, 

Wildlife Monitoring Plan, Surface Use Plan, Noxious 

Weed Management Plan and Water Management 

Plan. BLM would continue to implement the concept 

of adaptive management by using data from studies, 

monitoring and inspections to guide approvals of 

federal lease operations. POD requirements, the use 

of state and federal permits, lease stipulations, as well 

as the use of surface owner agreements and other 

management actions as described in Alternative E 

would also be features of this alternative. 

Like Alternative F, Alternative H would use 

watershed-level analysis to evaluate resource effects 

from CBNG and other activities occurring within the 

affected watersheds. Vegetation disturbance may be 

reduced based on results of the watershed-level 

analysis used to evaluate development proposals. 

Disturbance in individual watersheds would be

limited to prevent the potential for fragmentation of 

habitat for species of concern. 

The combined numerical limits for cumulative and 

watershed development, coupled with the disturbed 

habitat limit would necessitate a varied geographical 

development and corresponding vegetation 

disturbance pattern across the CBNG Planning Area. 

Only a few watersheds (Upper Tongue, Lower 

Tongue, Middle Powder and Little Powder) would 

likely be developed in the initial three to five year 

period, while the remaining watersheds would be 

developed in later years.

Operators would be required to include noxious weed 

management plans in their PODs to prevent the 

spread of noxious weeds. The noxious weed 

management plans must include measures to prevent 

the spread of weed seeds from any vehicles and 

equipment from or prior to mobilization to the project 

area. In the reclamation plans, early serial plants 

would be specified for revegetation to provide a 

quick cover before noxious weeds could become 

established. 

Indirect effects to vegetation would be similar to 

Alternative B through F, but would be reduced by the 

mitigation measures included in the PODs. Habitat 

could be disturbed or lost with the vegetation 

disturbance associated with well pads, roads, 

pipelines and utility lines. Roadways would provide 

greater access and more potential for disturbance, 

illegal harvest, or harassing of protected species.

Crow Reservation

Impacts to the Crow Reservation would be similar to 

those described in general for Alternative H. 

Operator PODs requiring consultation with tribes 

would be developed for all proposed CBNG 

development within 5 miles of the Crow Reservation. 

BLM would require site-specific groundwater and air 

analyses submitted as part of the operator’s POD. 

Resource protection protocols and mitigation

measures based on watershed-level analysis and 

monitoring of development would provide additional 

opportunities for protection of reservation resources. 
CHAPTER 4

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Northern Cheyenne Reservation

Impacts to the Northern Cheyenne Reservation would 

be similar to those described for the Crow 

Reservation. Specific mitigation measures proposed 

by the Northern Cheyenne Tribe that could be 

implemented by the BLM are described in the 

Northern Cheyenne Tribe Mitigation Appendix. 

Conclusions

Residual impacts would be similar to Alternative F. 

Site-specific PODs, watershed-level of analysis and

multiple screens would likely reduce potential effects 

to species of concern under Alternative H relative to 

Alternatives B through F. Reclamation after well 

abandonment may revegetate well sites and roads, 

but not necessarily restore the sites to previous 

vegetation or habitats, resulting in native habitat loss. 

Cumulative Impacts

The area of habitat disturbance and the types of 

cumulative impacts from Alternative H would be the 

same as described for Alternative F. However, the 

timing and location of habitat disturbance would vary 

for this alternative versus Alternatives B through E 

due to the watershed-based limits and multiple 

screens imposed on federal well development for 

Alternative H. Cumulative impacts may occur from 

coal mining operations within the Planning Area and 

the proposed Tongue River Railroad in addition to 

proposed CBNG development. Vegetation would be 

destroyed within the disturbed area of each coal mine

and reclamation will generally result in an increase in 

grasslands with less plant diversity than was 

originally present. The proposed TRR would result in 

the disturbance of approximately 513 to 542 acres of 

vegetation. CBNG development in Wyoming may 

increase flows of rivers entering Montana, resulting 

in potential erosion of wetland and riparian 

communities and habitat degradation.
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Visual Resource Management

Visual Resource Management

Visual resources include Montana features such as landform, 

water, vegetation, color, adjacent scenery, uniqueness, 

structures and man-made features of aesthetic value 

Alternative A

No Action (Existing CBNG Management) 

• Federal and State: 

− Dust emissions would reduce visibility to a small 

degree near active field operations

− Well pads, roads and compressors would disrupt the 

visual landscape. Semi-permanent structures are 

designed to blend into the surrounding environment

− Drill rigs, two-track trails, heavy road-making 

equipment and generators would disrupt the visual 

landscape short-term 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• There would be impacts to BLM VRM Class III and IV 

areas only.

• Type of impacts common to Alternative A would occur 

under Alternative B, at a scale commensurate with 

development.

• View shed impacts from road network could last for 

20 years until reclamation occurs.

Alternative C

Emphasize CBNG Development

• Impacts common to Alternative B would occur with 

Alternative C, in addition to the following:

− Above ground power lines would greatly impact 

skyline and viewshed.

− Visual impacts from roads and utility lines are 

greatest with this alternative.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Impacts common to Alternative B would occur with 

Alternative D, in addition to the following: 

− Production related roads that are not reclaimed and 

made part of the permanent road network would 

result in permanent visual impact.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Impacts would be reduced by the mitigation measures in 

the Project Plan for visual resources.

Alternative F

Phased Development Multiple Screens (High Range)

• Impacts would be similar to Alternative E.

• Locations and amounts of impacts would vary compared 

to the other alternatives based on annual and watershedbased federal CBNG development limits. 

Alternative G 

Phased Development Multiple Screens (Low Range)

• Impacts would be similar to Alternative F in the sequence 

of development but would result in lower impacts than the 

other action alternatives.

Alternative H

Preferred Alternative - Multiple Screens

• Impacts would be similar to or less than Alternative F in 

the sequence of development, but could result in lower 

visual impacts than the other alternatives due to the 

screening process and use of mitigation and management 

plans for development. 

Assumptions

Based on the Visual Resource Management (VRM) 

class, BLM stipulations and conditions of approval 

would require special design, including location, 

painting and camouflage, to blend with the natural 

surroundings and meet visual quality objectives for 

the area. A standard component typically includes 

painting facilities to camouflage them and a standard 

color may be specified.

Impacts From Management 

Common to All Alternatives

Visual resources would be impacted to varying 

degrees by oil and gas exploration and production 

activities. Exploration would involve minor visual 

impacts from clearing operations for access to 

exploratory sites. The majority of this impact would 

be expected to result from access road construction, 

site construction, drill rig operations and on-site 

generator use. Short-term visual impacts would occur 

where construction and drilling equipment is visually 

evident to observers. Long-term impacts would occur 

from construction of roads and pads, installation of 

facilities and equipment, vegetation removal and

change in vegetation communities. These would 

produce changes in landscape line, form, color and

texture.

Impacts would occur locally on a case-by-case basis 

as the native vegetation is disturbed and small 

structures are erected. Landscape line, form, color

and texture would all be expected to change. The 

view to travelers throughout much of the Powder 

River area is a high plain with low-lying scrub-shrub 

vegetation and periodic rock outcrops. In the Castle 

Rock Project, there is rough terrain, high hills and 

buttes and timber present. Much of the area is very 

scenic and quite a contrast to the landscape of open 

prairie that might be found in other areas of the 

Powder River Basin. Visual impacts may include 

building roads in rough terrain or cutting timber. 
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Introducing man-made structures into this landscape, 

although small and painted for camouflage, changes 

the overall nature of the visual resource. 

Four thousand acres of surface mining expansion 

under permit consideration may be approved this 

year. This mining activity may affect some visual 

resources in those areas for the next 20 to 30 years. 

Construction and operation of the Tongue River

Railroad would result in additional cumulative 

impacts to visual resources. The overall purpose of 

the proposed rail line is to transport coal from mines 

in the Powder River Basin and Tongue River Valley 

to markets in the Midwest and northeastern states. 

Analysis of the proposed project concluded that there 

would be very low to moderate long-term impacts to 

the scenic quality of the landscape along much of the 

approximately 130 miles of proposed route. Visual 

impacts would result from construction of fill prisms 

in several locations and from visibility of trains from 

sensitive areas. Impacts from construction of fill

prisms would be designed so that the cuts would fit 

with natural contours and surrounding environment 

and then planted. Additional short-term impacts 

would occur as a result of construction activities. 

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

CBNG production well activities would have visual 

impacts. CBNG wells, typically covered in a box, or 

“housing” for protection from weather, are isolated 

structures approximately 4 feet high by 4 feet wide 

by 4 feet long. The wells are scattered across a wide 

area and are connected to field compressors. The 

compressors are larger and create more of a visual 

impact-although in a much smaller area because these 

structures are more widely distributed. Compressors 

range in size from field compressors at 8x12x8 

(width, length, height; in feet) to sales compressors at 

12x18x10. Visual impacts also would arise from 

construction activities related to developing access to 

the sites. Exploration well activities may have shortterm visual impacts if the exploration wells are not 

converted to production wells. These short-term 

impacts (approximately 2 months) would be from the 

visual effects of the drill rig, portable generator and

access road.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative A. If there 

were no CBNG development on tribal lands, then 

there is expected to be minimal, if any, impacts on 

visual resources for the reservation. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusions

Exploration wells would cause short term impacts 

and impacted areas will be repaired on an as-needed 

basis. Minimal permanent visual impacts 

(approximately 500 acres) are anticipated within the

CX Ranch due to well houses, compressor stations, 

power lines and associated roads. 

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Visual impacts would occur from the development of 

CBNG wells in this alternative for lands in VRM

Classes III and IV. VRM Class I and II lands would 

not be developed and the No Surface Occupancy 

stipulation applies. The Controlled Surface Use 

stipulation would be applied to Class III and IV 

lands. On lands without VRM objectives, a Visual 

Resource Inventory and Visual Contrast Rating 

would be accomplished, on a case-by-case basis, to 

determine the VRM class, visual qualities, site 

specific impacts and mitigation. On lands with VRM 

objectives, a Visual Contrast Rating would be 

completed, on a case-by-case basis, to determine site 

specific visual impacts and mitigation. Impacts from 

utilities would be minimal as power lines are buried 

and other utilities are concentrated within roadway 

corridors.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative A.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusions

Residual visual impacts would include the impact of 

the expanded road network when viewed from a 

distance or from higher elevations. Cumulative 
CHAPTER 4

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impacts would include the visual impact of additional 

roads when combined with existing roads and new 

roads being constructed for other uses. 

Alternative C—Emphasize CBNG 

Development

For Alternative C, visual impacts would occur from 

the development of CBNG wells for lands in VRM 

Classes II, III and IV. VRM Class I lands would not 

be developed and the No Surface Occupancy 

stipulation would apply. The Controlled Surface Use 

stipulation would be applied to Class II, III and IV 

lands. On lands without VRM objectives, a Visual 

Resource Inventory and Visual Contrast Rating 

would be accomplished, on a case-by-case basis, to 

determine the VRM class, visual qualities, site 

specific impacts and mitigation. On lands with VRM 

objectives, a Visual Contrast Rating would be 

completed, on a case-by-case basis, to determine site 

specific visual impacts and mitigation. 

Power lines would be aboveground in this alternative 

and roads would be allowed to be placed according to 

operator plans. This would result in power lines 

where none now exist, as well as a wider expanse of 

roads.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative C. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusions

Residual visual impacts would include the impact of 

the expanded road network when viewed from a 

distance or from higher elevations. There also would 

be a network of power lines visible from many 

places.

Cumulative impacts would be the same as described 

for Alternative B.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Visual impacts would be the same as described for 

Alternative B.

Conclusions

Residual and cumulative impacts are the same as 

described for Alternative B.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Visual impacts would occur from the development of 

CBNG wells for lands in VRM Classes II, III and IV. 

VRM Class I lands would not be developed and the 

No Surface Occupancy stipulation would apply. The 

Controlled Surface Use stipulation would be applied 

to Class II, III and IV lands providing options for 

lessening the visual impact through design and 

landscape features. On lands without VRM 

objectives, a Visual Resource Inventory and Visual 

Contrast Rating would be accomplished, on a caseby-case basis, to determine the VRM class, visual 

qualities, site specific impacts and mitigation. On 

lands with VRM objectives, a Visual Contrast Rating 

would be completed, on a case-by-case basis, to 

determine site specific visual impacts and mitigation. 

Visual contrast Ratings would be completed at the 

APD or POD stage to identify site specific impacts 

and determine mitigation.

This alternative does allow for installation of 

pipelines, power lines and roads where there are none 

now. But, it also requires that the operator minimize 

or mitigate impacts from these activities in the 

Project Plan and state how the surface owner was 

consulted for input on the location of roads, pipeline 

and utility line routes. It also allows, at the surface 

owner’s discretion, the closing and rehabilitation of 

roads or the option of leaving them open, after well 

abandonment. 

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative E. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusions

Use of the mitigation plan as part of the Project Plan 

would lessen many of the visual impacts but would 

not eliminate them. New roads and power lines 
CHAPTER 4

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would be a residual visual impact from this 

alternative.

There would be cumulative visual impacts from the 

combination of new and existing roads and utilities.

Alternative F—Phased Development 

Multiple Screens (High Range)

Overall visual impacts at the end of the 20-year 

development cycle would be similar to Alternative E

because both alternatives will have approximately the 

same cumulative level of development. Based on the 

sequence of development predicted for this 

alternative, visual impacts from federal CBNG 

development would be lower during the first few

years of the planning period than any of the other 

action alternatives. Impacts would accumulate each 

year thereafter as the number of developed wells 

increases. Since development is distributed over 

several watersheds, those with the greatest number of 

developed wells would experience the greatest visual 

impacts from federal CBNG development. The 

greatest effects due to federal development are 

predicted to be in the Lower and Upper Tongue, 

Middle Powder and Rosebud watersheds. Cumulative 

impacts will result over time and within the 

watersheds as both federal and state/private CBNG 

well development occurs. 

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described for Alternative E. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusions

Use of management and mitigation plans would 

lessen many of the visual impacts but would not 

eliminate them. New roads and aboveground power 

lines would be a residual visual impact from this 

alternative. As with Alternative E, short-term 

construction impacts would be greater than the longterm impacts because the footprint of each well is 

smaller than the necessary construction footprint.

Cumulative impacts would be similar to those 

described under Alternative E.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Overall visual impacts at the end of the 20-year 

development cycle would be noticeably less than 

those of Alternative F because Alternative G would 

result in approximately one-third the number of 

developed wells. Alternative G would be similar to 

Alternative F in the sequence of development 

predicted for this alternative. Impacts would

accumulate each year thereafter as the number of 

developed wells increases. Since development is 

distributed over several watersheds, those with the 

greatest number of wellheads would experience the 

greatest visual impacts from federal CBNG 

development. As with Alternative F, the greatest 

effects due to federal development are predicted to be 

in the Lower and Upper Tongue, Middle Powder and

Rosebud watersheds. Cumulative impacts will result 

over time and within the watersheds as both federal 

and state/private development occurs. 

Crow Reservation

Impacts on the Crow Reservation would be similar in 

nature to those described for Alternative F; however 

the amount of impacts would be approximately onethird of Alternative F due to limited well 

development under Alternative G. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative.

Conclusions

Use of management and mitigation plans would 

lessen many of the visual impacts but would not 

eliminate them. New roads and aboveground power 

lines would be a residual visual impact from this 

alternative. As with Alternative F, short-term 

construction impacts would be greater than the longterm impacts because the footprint of each operating 

well is smaller than the necessary construction 

footprint.

Cumulative impacts would be less than those 

described under Alternative F due to the reduced 

amount of well development.

Alternative H—Preferred Alternative - 

Multiple Screens

Overall visual impacts would be similar to or less 

than Alternatives E and F. Based on a sequence of 
CHAPTER 4

Visual Resource Management

4-255

development similar to that predicted for Alternative 

F, visual impacts from federal CBNG development 

under Alternative H would be lower during the first 

few years of the planning period than Alternatives B 

through E. Impacts would accumulate each year 

thereafter as the number of developed wells 

increases. Since development is distributed over 

several watersheds, those with the greatest number of 

developed wells would experience the greatest visual 

impacts from federal CBNG development. The 

greatest effects due to federal development are 

predicted to be in the Lower and Upper Tongue, 

Middle Powder and Rosebud watersheds. Cumulative 

impacts will result over time and within the 

watersheds as both federal and state/private CBNG 

well development occurs. 

Visual consequences under Alternative H could be 

less than the other alternatives because each proposal 

for development would be subject to review against 

the four resource screens (air, water, wildlife, Native 

American concerns), as well as planning and 

mitigation requirements. This review process would 

balance CBNG development with protection of the 

natural environment. While visual resources do not 

have an individual screen for the review process, it is 

considered in the individual analyses. Additionally,

key environmental and wildlife conditions are subject 

to the resource screens. Protection of these conditions 

would contribute to a more natural-appearing visual 

character. 

Visual impacts due to erosion from CBNG-produced 

water could be less than Alternatives C, D and E and 

similar to Alternative F because the BLM would 

require a water management plan and use watershedbased thresholds for the volume of untreated water 

that could be discharged to surface waters from 

federal CBNG wells. 

Visual disturbance could be less than Alternatives E 

or F because there would be minimal road 

construction. Transportation corridors (proposed 

roads, flowline routes and utility line routes) would 

be located to follow existing routes, or areas of 

previous surface disturbance, where possible. In 

addition, low-voltage distribution power lines would 

be buried. 

Cumulative impacts would result within the 

watersheds as both federal and state/private 

development occurs. However, Alternative H 

includes watershed-level analysis as part of POD 

development and review to evaluate and address 

cumulative impacts as they are identified.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative H. If there 

were no CBNG development on tribal lands, then 

there are expected to be minimal, if any, impacts on 

visual resources for the reservation. The Native 

American concerns screen would provide an 

additional level of resource protection for 

development proposed within 5 miles of the 

reservation and in the vicinity of traditional cultural 

properties through consultation with the tribe and 

monitoring during development.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation

would be similar to those described for the Crow 

Reservation under this alternative. 

Conclusion

Use of the screening process and management and 

mitigation plans would lessen many of the visual 

impacts, but would not eliminate them. A limit on 

new roads construction and putting power lines 

underground would help maintain the naturalappearing landscape.

As with the other alternatives, short-term 

construction impacts would be greater than the longterm impacts because the footprint of each operating 

well is smaller than the necessary construction 

footprint.

Cumulative impacts would include the visual impact 

of additional roads, if any, when combined with 

existing roads and new roads being constructed for 

other uses.
CHAPTER 4

Wilderness Study Areas

4-256

Wilderness Study Areas

Wilderness Study Areas

There are 6 WSAs within the CBNG emphasis area

Alternative A

No Action (Existing CBNG Management)

• BLM WSAs are closed to oil and gas leasing so there 

would be no direct impact to WSAs. Because there would 

be no production activities in BLM planning areas under 

this alternative, there would be no impacts.

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• No direct impact to WSAs from CBNG development.

Alternative C

Emphasize CBNG Development

• No direct impact to WSAs from CBNG development.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• No direct impact to WSAs from CBNG development.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• No direct impact to WSAs from CBNG development.

Alternatives F & G

High and Low Range Phased CBNG Development

• No direct impacts to WSAs from phased CBNG 

development.

Alternatives H

Preferred Alternative - Multiple Screens

• No direct impacts to WSAs from CBNG development.

Assumptions

Wilderness Study Area (WSA) policy prohibits 

leasing of WSA lands for resource extraction subject 

to rights associated with valid claims and leases 

existing at the time of designation.

Impacts From Management 

Common to All Alternatives

BLM leasing restrictions are designed to protect 

WSAs from considerable impact. The WSA policy 

prohibits leasing of these lands for resource 

extraction. It is expected that WSAs will not be 

impacted through conventional oil and gas 

development under current management. Remote 

areas may be accessed as CBNG development 

proceeds, but this does not mean that WSAs will be 

impacted. Specific potential impacts to WSAs cannot 

be quantified until specific development proposals 

are received.

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG

Management)

State and private lands would be impacted by CBNG

production activity. There would be no production 

activities in BLM planning areas under this 

alternative and therefore no impacts from CBNG

activities. 

Conclusion

Impacts from this alternative would be similar to 

management common to all alternatives. Since 

stipulations for WSAs prevent leasing of these lands 

for resource extraction, there are expected to be no 

major impacts to WSAs. 

There are no cumulative impacts from CBNG

development.

Alternative B—Emphasize Soil, Water, 

Air, Vegetation, Wildlife and Cultural 

Resources

Alternative B would allow development while 

emphasizing the protection of natural and cultural 

resources. Under this alternative development would 

result in increased access to remote areas. The 

impacts from this alternative would be similar to 

those described under Impacts From Management 

Common to All Alternatives. 

Conclusion

Impacts from this alternative would be similar to 

those described under Alternative A.

Alternative C—Emphasize CBNG

Development

Alternative C would emphasize CBNG exploration 

and development with minimal restrictions. The 

impacts from this alternative would be similar to 

management common to all alternatives.

Conclusion

Impacts from this alternative would be similar to 

those described under Alternative A.
CHAPTER 4

Wilderness Study Areas

4-257

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Alternative D would encourage CBNG development 

while maintaining existing land uses and protecting 

downstream water consumers. The impacts from this 

alternative would be similar to management common 

to all alternatives.

Conclusion

Impacts from this alternative would be similar to 

those described under Alternative A.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Alternative E would allow CBNG development 

subject to existing planning restrictions and balances 

CBNG development and the protection of the natural 

environment. The impacts from this alternative would 

be similar to those described under Impacts From 

Management Common to All Alternatives. 

Conclusion

There are no cumulative impacts from CBNG

development.

Alternative F—Phased Development 

Multiple Screens (High Range)

Alternative F would allow CBNG development 

subject to watershed level planning coupled with 

phased development. The impacts from this 

alternative would be similar to those described under 

Impacts From Management Common to All 

Alternatives. 

Conclusion

There are no cumulative impacts from CBNG 

development.

Alternative G—Phased Development 

Multiple Screens (Low Range)

Alternative G would be the same as Alternative F in 

that it would allow CBNG development but at a 

lower number of allowed federal APDs. 

Conclusion

There are no cumulative impacts from CBNG 

development.

Alternative H—Preferred Alternative - 

Multiple Screens

Alternative H would allow CBNG development 

subject to multiple screens, increased monitoring and 

long-term corridor planning. 

BLM leasing restrictions are designed to protect 

WSAs from considerable impact. The WSA policy 

prohibits leasing of these lands for resource 

extraction. It is expected that WSAs will not be 

impacted through CBNG development. 

Mitigation

There are no mitigation measures necessary since no 

development is current allowed within WSAs. 

Conclusion

There are no cumulative impacts to WSAs from 

regional projects as forecasted at this time. 
CHAPTER 4

Wildlife

4-258

Wildlife

Wildlife

Mammal Species: 10 bats. 8 shrews, 34 small mammals and 

lagomorphs, 17 predators, 4 big game, 

Bird Species: 32 waterfowl, 33 shore & wading birds, 

18 diurnal & 11 nocturnal raptors, 8 gallinaceous, 

8 wood peckers, 137 songbirds

Reptiles and Amphibian species: 1 salamander, 4 frogs, 

4 toads, 3 turtles, 2 lizards, 9 snakes

Species of Concern consist of 16 mammals, 9 reptiles and 

amphibians, and 22 birds, including: Sage-grouse, 

Mountain Plover, Bald Eagle, Interior Least Tern, 

Peregrine Falcon, Gray Wolf, Black-tailed Prairie Dog, 

Canada Lynx, Black-footed Ferret, Grizzly Bear

Alternative A

No Action (Existing CBNG Management)

• Direct impacts include habitat loss, death from vehicle 

collisions and effects associated with greater human access

into previously untraveled areas.

• Indirect impacts on wildlife include disturbance and 

displacement, stress, power lines, noxious weed invasion, 

user-created roads, habitat fragmentation, water quality 

degradation from road runoff and increased livestock 

grazing.

• Indirect impacts on wildlife would occur on 33,840 to 

84,000 acres.

• Potential indirect impacts to T&E species, such as human 

disturbance, increased illegal harvest or collisions with 

vehicles, would be low because of the limited number of 

CBNG wells permitted.

• Species of concern that are not federally protected may be 

impacted by habitat loss, disturbance and habitat changes. 

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• Same as Alternative A but on a much larger scale. 

Twenty-five times as many wells, roads and utility 

corridors as under Alternative A. 6,680 miles of roads 

(2.9 to 8.8 miles per square mile). 20,697 miles of utility 

corridors (9 to 27.1 miles per square mile). Indirect 

impacts to wildlife on 884,000 to 4.7 million acres from:

• Loss of high value habitats such as prairie dog towns, 

sage-grouse leks and big game winter range.

• Loss of intermittent wildlife habitat associated with 

streams because of groundwater withdrawal.

• Potential indirect impacts to T&E species, such as human 

disturbance, increased illegal harvest or collisions with 

vehicles could occur, but impact would be less than 

Alternatives C or D with the restricting of utilities and 

roadways to the same corridor.

• All species of concern that are not federally protected 

may be impacted by habitat loss, disturbance and habitat 

changes. 

Alternative C

Emphasize CBNG Development

• Similar impacts as Alternative B. Indirect impacts to 

wildlife would occur on 884,000 to 4.7 million acres from:

− Discharge of untreated CBNG water into drainages 

would impact riparian and wetland habitat and 

associated species because of poor water quality and 

erosion.

− Increased livestock grazing within two miles of CBNG 

discharges that occur in areas without summer water

− Potential indirect impacts to T&E species, such as 

human disturbance, increased illegal harvest or 

collisions with vehicles, are greater under this 

alternative than any other because of the increased 

number of CBNG well permits. 

− Potential indirect impacts to T&E species from 

changes in riparian habitat. Bald Eagles and Interior 

Least Terns may also be affected if SAR changes 

affect forage fish.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• Impacts would be similar to Alternative B:

− Discharged treated CBNG water would erode riparian 

and wetland habitat

− Potential indirect impacts to T&E species, such as 

human disturbance, increased illegal harvest or 

collisions with vehicles would occur at a level less 

than Alternative C.

− Potential indirect impacts to T&E species from 

hydrology changes caused by increased water levels 

may impact nesting Interior Least Terns. If hydrology 

changes from surface water runoff, cause riparian 

vegetation changes, other T&E species may be 

impacted as well, such as nesting Bald Eagles.

− Species of concern that are not federally protected may 

be impacted by habitat loss, disturbance and habitat 

changes. 

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• Direct and indirect impacts would occur similar to 

Alternative B. 

• Indirect impacts to wildlife would occur on 884,000 to 

4.7 million acres depending on development spacing.

• Loss of intermittent wildlife habitat associated with 

streams because of groundwater withdrawal.

− This alternative would not directly impact any T&E 

listed wildlife species.

− Potential indirect impacts to T&E species, such as 

human disturbance, increased illegal harvest or 

collisions with vehicles could occur.

− Species of concern not federally protected may be 

impacted by habitat loss, disturbance and habitat 

changes. These impacts may be less than under 

Alternatives B, C, & D through the implementation of 

the Wildlife Monitoring and Protection Plan. 

However, this alternative would include more holding 

ponds than any other development alternative and

consequently, Alternative E would include a greater 

risk of West Nile virus infection to sage-grouse than 

any other development alternative. The risk would be 

minimized by implementing BMPs to control 

mosquito populations associated with holding ponds. 

• More water would be available for wildlife and livestock 

as a result of CBNG production. 

• An adaptive management strategy, included in the 

Wildlife Monitoring and Protection Plan, would help to 

minimize impacts to wildlife and habitat by:

− Utilizing and evaluating new information to change 
CHAPTER 4

Wildlife

4-259

or form additional conditions of approvals.

− Monitoring habitat use/wildlife populations and 

reclamation activities that will allow mitigation

measures and stipulations to be evaluated for 

effectiveness. 

Alternative F

Phased Development Multiple Screens (High Range)

• Direct impacts are expected to be less than Alternatives 

B, C, D and E during the time when fewer wells are 

being drilled and fewer production facilities are installed.

• If habitat thresholds are met and well development is 

restricted, acreages of indirect impacts would be the less 

than Alternatives B, C, D and E.

• Indirect effects from new roads and new utility lines 

would be similar to Alternatives B and D, but less than 

Alternatives C and E while federal restrictions are 

applied.

• Loss of wildlife habitat associated with streams as a 

result of groundwater withdrawal.

• Thresholds for important sagebrush-steppe habitat 

impacts could result in slightly less impacts to wildlife

than under Alternative E particularly sage-grouse and 

other sagebrush and grassland associated species 

• Species may be impacted by habitat loss, disturbance and

habitat changes. These impacts may be less than under 

the other development alternatives due to established 

habitat and well development thresholds and the 

implementation of the Wildlife Monitoring and 

Protection Plan. However, this alternative would include 

a greater risk of West Nile virus infection to sage-grouse 

than Alternatives B, C, D, or G.

• Potential impacts to sage-grouse and other sagebrush 

dependant species would be lessened due to conditions 

placed on development within crucial sage-grouse habitat 

areas.

• Potential indirect impacts to T&E species, such as human 

disturbance, increased illegal harvest, or collisions with 

vehicles are present, but less so than other development 

alternatives due to implementation of the Wildlife 

Monitoring and Protection Plan and established habitat 

and well development thresholds.

• An adaptive management strategy, as described under 

Alternative E above, would help to minimize impacts to 

wildlife and habitats.

Alternative G

Phased Development Multiple Screens (Low Range)

• Acres of direct and indirect impacts would be less than 

all other development alternatives.

• Indirect effects from new roads and new utility lines 

would less than all other development alternatives.

• Species may be impacted by habitat loss, disturbance and

habitat changes. These impacts would be less than under 

the other development alternatives due the less amount of 

well, road and utility line development, as well as the 

implementation of the Wildlife Monitoring and 

Protection Plan. However, the risk of West Nile Virus to 

sage-grouse would be greater than Alternatives B, C and

D, but less than Alternatives E or F. 

• Potential indirect impacts to T&E species, such as human 

disturbance, increased illegal harvest, or collisions with 

vehicles, but less so than Alternatives B, C, D, E and F.

• An adaptive management strategy, as described under 

Alternative E above, would help to minimize impacts to 

wildlife and habitats.

Alternative H 

Preferred Alternative - Multiple Screens

• There would be less potential for displacement of sagegrouse as Alternative H calls for maintaining sage-grouse 

populations consistent with control populations.

• Rate of development managed by the number of Federal 

APDs that would be approved per year to protect other 

resources.

• Geographic development of CBNG resources managed 

by the location of federal APDs approved to protect other 

resources.

• Amount of acres disturbed in crucial habitat areas 

managed by limits associated with federal wells

• Protection of tribal resources from federal wells within 5 

miles of reservation boundaries

• BLM would require wildlife monitoring and use adaptive 

management techniques to protect wildlife

Less potential for the displacement of sage-grouse from crucial 

habitat areas due protecting source populations

Assumptions

CBNG exploration, production and abandonment on 

BLM-administered minerals is subject to the 

stipulations summarized in Table 4-67. These 

stipulations are recommended for, but do not 

necessarily apply to, CBNG-related activities on nonBLM-administered surfaces. Therefore, the 

stipulations would avoid some of the potential impacts 

on BLM-administered surfaces, but may or may not 

avoid impacts on non-BLM-administered surfaces. The 

success of these stipulations in avoiding impacts would 

require collection of site-specific information 

regarding the resources to be protected in relation to 

exploration, production and abandonment plans, 

followed by strict adherence to the terms of the 

stipulations. For the purposes of this analysis it is 

assumed that the stipulations offer some protection to 

wildlife species on BLM-administered lands. It is 

further assumed that these stipulations which are very 

species specific, offer some degree of protection to 

many other species that use the same habitat during the 

same time period.

The assumption is made that existing stipulations 

would provide some protection to sage-grouse habitat 

including lek areas, nesting habitat and winter range. It 

is recognized that these actions would not completely 

protect this species. Mitigation measures within the 

Wildlife Monitoring and Protection Plan (WMPP) 

located in the Wildlife Appendix will provide 

additional protective measures. Lease stipulations and 

terms and conditions would provide protection to 
CHAPTER 4

Wildlife

4-260

TABLE 4-67

EXISTING WILDLIFE-RELATED LEASE STIPULATIONS COVERING CBNG EXPLORATION AND 

DEVELOPMENT ON BLM-ADMINISTERED SURFACES 

Resource No Surface Use No Surface Occupancy

No Surface Use or 

Occupancy

Riparian areas X 

100-year floodplains of major rivers, 

streams and water bodies 

X 

Water bodies and streams X 

Crucial big game and sage-grouse

winter range*

December 1 - March 31

Elk calving areas* April 1 - June 15

Powder River Breaks bighorn sheep 

range

Within designated 

bighorn sheep range

Grouse leks Within 1⁄4 mile of lek

Grouse nesting zones* Within 2 miles of leks 

from March 1 - June 15

 

Raptor nests* Within 1⁄2 mile from 

March 1 to August 1, 

within 1⁄2 mile of raptor 

nest sites which have been 

active within the past 2 

years.

Within 1⁄4 mile of nest

Bald eagle nests and nesting habitat Within 1⁄2 mile from 

March to August 1, within 

1⁄2 mile of raptor nest sites 

which have been active 

within the past 2 years.

Within 1⁄2 mile of nests 

active in the last 7 years 

and within riparian area 

nesting habitat

Peregrine falcon Within 1 mile of nests

Ferruginous hawk Within 1⁄2 mile of nests 

active within 2 years

Piping plover Within 1⁄4 mile of wetlands 

identified as piping plover 

habitat

Interior least tern Within 1⁄4 mile of wetlands 

identified as Interior Least 

Tern habitat

Prairie dog colonies > 80 acres Controlled surface use

Note: These stipulations are attached to leases and can affect exploration and construction

*Stipulation does not apply to operation and maintenance of production facilities.

Please refer to Table MIN-5, Minerals Appendix, for a listing of resource mitigation.
CHAPTER 4

Wildlife

4-261

raptors and the mountain plover. Protective measures 

contained in the WMPP (if fully implemented) would 

help reduce, but cannot avoid all impacts to all species 

of wildlife.

The DNRC TLMD may apply the following 

stipulations on a case-by-case basis to school trust 

lands leased for oil and gas exploration, development 

and production. The noxious weed stipulation is placed 

on all oil and gas leases issued by TLMD. Some of the 

stipulations indirectly relate to wildlife, while others 

are more specific. The dates on the timing restriction 

stipulation vary depending on the wildlife species to 

which it applies.

• Notification: Lessee shall notify and obtain

approval from the DNRC’s TLMD prior to 

constructing well pads, roads, power lines and

related facilities that may require surface 

disturbance on the tract. Lessee shall comply with 

any mitigation measures stipulated in TLMDs 

approval.

• Weeds: The lessee shall be responsible for 

controlling any noxious weeds introduced by 

Lessee’s activity and shall prevent or eradicate the 

spread of those noxious weeds onto land adjoining 

the lease premises.

• Sensitive Areas: This lease includes areas that 

may be environmentally sensitive. Therefore, if 

the lessee intends to conduct any activities on the 

lease premises, the lessee shall submit to TLMD 

one copy of an Operating Plan or Amendment to 

an existing Operating Plan, describing in detail the 

proposed activities. No activities shall occur on 

the tract until the Operating Plan or Amendments 

have been approved in writing by the Director of 

the Department. TLMD shall review the Operating 

Plan or Amendment and notify the lessee if the 

Plan or Amendment is approved or disapproved.

After an opportunity for an informal hearing with 

the lessee, surface activity may be denied or 

restricted on all or portions of any tract if the 

Director determines in writing that the proposed 

surface activity would be detrimental to trust 

resources and therefore not in the best interests of 

the trust.

• Wildlife Restrictions:

− To protect certain wildlife during periods 

important to their survival, surface occupancy 

or other activity shall be restricted from 

March 15 through July 15 of each year unless 

otherwise authorized in writing by the TLMD.

− Potential wildlife conflicts have been 

identified for this tract. The TLMD would 

contact either the Montana Department of 

Fish, Wildlife and Parks office or the FWS 

office in the area for advice on alleviating any 

possible conflicts caused by lessee’s proposed 

activities. Additional mitigation measures

may be required.

− Wildlife species of concern have been 

identified on or near this tract. A survey in 

areas of proposed activity may be required 

prior to disturbance. Identified species would 

be avoided, unless otherwise authorized by 

the TLMD. Additional mitigation measures

may also be required.

• Miscellaneous Restrictions:

− Plant species of concern have been identified 

on or near this tract. A vegetation survey in 

areas of proposed activity would be required 

prior to disturbance. Identified rare plant 

species would be avoided, unless otherwise 

authorized by the TLMD.

− A critical weed problem exists on this tract. 

Additional mitigation measures would be 

required to prevent further spread of noxious 

weeds. The department may require such 

measures as power washing of vehicles, car 

pooling, timing restrictions for seismic, etc. to 

facilitate this prevention.

− This tract contains biological weed-control 

sites, which must be avoided unless otherwise 

authorized by TLMD.

• Other:

− Any activity within 1/8 mile of the river or 

lake/reservoir on or adjacent to this tract must 

be approved in writing by the TLMD prior to 

commencement. No surface occupancy would 

be allowed within the bed of the river, 

abandoned channels, the bed of the 

lake/reservoir, or on islands and accretions 

associated with the river or lake/reservoir.

− No activity shall be allowed within 100 feet 

of any perennial or seasonal stream, pond, 

lake, prairie pothole, wetland, spring, 

reservoir, well, aqueduct, irrigation ditch, 

canal, or related facilities without prior 

approval of the TLMD.

− Wooded areas on this tract would be avoided 

unless otherwise authorized by the TLMD.
CHAPTER 4

Wildlife

4-262

In addition to these stipulations, motorized vehicle use 

for recreationists on state trust lands is restricted by 

current policy to federal, state and dedicated county 

roads or other roads regularly maintained by the 

county, or to other roads that have been designated 

open by DNRC. Off road use is prohibited. Increased 

posting efforts, i.e., Walk-In Only signs, may be 

implemented by the TLMD to reduce unauthorized use 

of two-track trails and roads by recreationists to 

alleviate increased pressure on wildlife. Exploration 

for and development of CBNG wells would cause a 

wide range of both direct and indirect impacts on 

wildlife. The extent and duration of effects on wildlife 

would depend on the animal species, the type and 

quantity of vegetation removed, the nature and period 

of disturbance and the success of stipulations in 

reducing or avoiding some impacts. The impacts 

described below assume that the site-specific natural 

resource information and the stipulations discussed 

above are successfully used to avoid certain impacts on 

BLM-administered and state lands. 

As previously described, the No Action Alternative 

includes exploration for and development of a 

relatively small number of CBNG wells (compared to 

the other alternatives) and the associated roads, pads, 

power lines, pipelines, utility corridors, facilities and

human activities and presence. Many of the direct and 

indirect impacts of CBNG development on wildlife 

described for Alternative A would occur regardless of 

the number of CBNG wells developed, with the extent 

of impacts roughly proportional to the number of 

wells. These direct and indirect impacts are discussed

below under the No Action Alternative and referenced 

as appropriate in the discussion of the impacts of 

Alternatives B through H. Additional ecosystem-level 

impacts associated with the substantially larger number 

of CBNG wells that would be developed under 

Alternatives B through H are discussed under those 

alternatives.

For Alternatives A thru E, sage-grouse habitat would 

be managed in accordance with the current BLM 

policy for management of BLM sensitive species and 

as outlined in the FSEIS and WMPP; specifically, 

BLM sensitive species management cannot impact 

these species in a way that may cause further declines 

in the species population status. For Alternatives F and

G, a wildlife screen is included for the protection of 

wildlife habitat. For Alternatives F and G, additional 

sage-grouse population management prescriptions 

could also be implemented with the goal of 

maintaining the current sage-grouse populations (see 

WMPP for specifics). For Alternative H, BLM would 

apply broad or universal BMPs within crucial sagegrouse habitat, coupled with monitoring to determine 

the success of these BMPs. Development within sage 

grouse habitat would only be allowed if the operator 

can show the development will not result in the 

decrease in sage-grouse populations, when compared 

to control leks. Further restrictions could be 

implemented if monitoring shows the management is 

not effective in maintaining sage-grouse in the 

development areas.

Impacts From Management Common 

to All Alternatives

The responses of wildlife to facilities and activities 

associated with oil and gas development are complex 

but well documented (Wisdom et al. 2000; USDI and 

USDA 2001; Trombulak and Frissell 2000). Tolerance 

of various types of environmental disturbances varies 

among species and among individuals of the same 

species. The potential for impact is related to the 

timing and nature of the disturbance, severity of 

winter, habitats and species present, physiological 

status of the animal, hunting pressure and other 

disturbance factors and predictability of the 

disturbance. The scale of oil and gas development, 

number and length of associated roads and other 

facilities and implementation of measures to avoid or 

reduce impacts also influence the probability and 

severity of impacts on wildlife.

Direct and indirect impacts of road construction and 

use on wildlife and wildlife habitat have been well 

documented for oil and gas projects and other natural 

resource developments. Impacts include a wide range 

of biological effects, such as habitat loss, displacement 

because of noise and human disturbance and stress. 

The types of impacts expected to result from oil and 

gas development would be similar to those described 

in detail under Alternative A for CBNG development. 

The extent of the impacts would vary depending on the 

level of development. 

A detailed discussion of impacts and mitigation

measures for wildlife is included in the remainder of 

this section and in the Wildlife Appendix. This 

discussion addresses the direct and indirect 

quantitative and qualitative impacts that would likely 

result from CBNG development in the Powder River

and Billings RMP areas. The impacts from 

conventional oil and gas development would be similar 

to those anticipated for CBNG but at a scale associated 

with conventional oil and gas development as 

identified in the Miles City District’s Oil and Gas 

Final EIS (BLM 1992). 

Construction and operation of the proposed TRR

would directly and indirectly affect wildlife in the 

project area, primarily big-game species (deer and 

pronghorn) and birds (upland, waterfowl, songbirds 
CHAPTER 4

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4-263

and raptors). Direct impacts would include the loss of 

some wildlife habitat within the ROW and 

displacement of some wildlife within or near the 

ROW. Other wildlife impacts could include 

elimination of relatively nonmobile species; loss of 

animals due to collision with trains or maintenance 

vehicles; creation of a barrier to some species;

potential damage or elimination of habitat by dust, 

herbicides, fuel or other hazardous material spills and

fire; and disturbances to nearby animals. Indirect 

impacts would include general demands on the 

environment associated with increased human 

population, such as increased county road wildlifevehicle collisions, displacement of wildlife by 

recreationists and increased illegal harvest and hunting

(STB 2004). Construction and operation of the TRR

would be in accordance with all state and federal rules 

and regulations and would use mitigation measures and 

BMPs to minimize impacts to wildlife.

Impacts From Management Specific 

to Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

CBNG exploration and production includes 

development of roads, pads, power lines, pipelines, 

utility corridors and facilities as well as human 

activities and regular human presence. Much of this 

activity would occur in the relatively undisturbed 

native short grass prairie of eastern Montana, resulting 

in both direct and indirect impacts on wildlife. Those 

impacts would be localized around CBNG exploration 

and production sites and proportional to the level of 

activity at a particular location. The following 

discussion documents the types of impacts that would 

be expected from CBNG-related actions. These 

impacts would occur on BLM, state and private lands. 

While the types of impacts described below would 

occur under all of the alternatives, the extent of the 

impact would be roughly proportional to the extent of 

CBNG development under each alternative. The 

number of CBNG exploratory and development wells 

under the No Action Alternative is 1/20th the number 

that would be developed under the other alternatives. 

Therefore, the extent to which these impacts would 

occur under the No Action Alternative is relatively 

minor compared to the other alternatives.

With a few exceptions, the same types of impacts to 

wildlife would occur under all of the alternatives. 

Therefore, they are described under Alternative A 

below. Differences in the type or extent of impacts 

between alternatives are noted for Alternatives B 

through H. 

Direct habitat loss and direct and indirect impacts 

because of habitat disruption and wildlife disturbance 

caused by roads, pipelines and utility corridors would 

cause the bulk of the impacts on wildlife. Numerous 

studies have documented the direct and indirect 

impacts on wildlife from road development, human 

presence in formerly remote areas and facilities 

construction (Trombulak and Frissell 2000, Wisdom 

et al. 2000). The nature of these impacts and how they 

relate to exploration, development and maintenance of 

CBNG wells is discussed in the text that follows. In 

most instances, the impacts would occur during all 

CBNG phases. Exceptions are noted as appropriate. 

Direct impacts would include loss of habitat to 

accommodate project features. They would persist for 

the duration of CBNG activities and, in the case of loss 

of habitat value, beyond that time. Some degree of 

habitat loss and degradation would continue following 

CBNG abandonment because of ecological differences 

between reclaimed sites and native vegetation.

The amount and types of habitat that would be directly 

lost from exploration and development are described in 

the Vegetation section. The species that would be 

affected by direct habitat loss would depend on the 

location of CBNG exploration and development and 

the types of habitat affected. Based on the average area 

expected to be disturbed by exploration and 

development of each CBNG well, about 675 acres 

would be impacted during exploration, a total of 1,500 

acres would be impacted in the short term by well 

development (including the 675 exploration acres) and

500 acres would be subject to long term impacts during 

operations under Alternative A. Direct impacts on 

wildlife would also include mortality as relatively less 

mobile small mammals, reptiles and amphibians are 

killed during road and other site construction. Smaller 

mammals, reptiles and amphibians are most likely to 

be directly killed by vehicles and are vulnerable when 

crossing roadways (USDI and USDA 2001). 

Amphibians are especially vulnerable to being killed 

on all types of roads because their life histories often 

involve migration between wetland and upland habitats 

and individuals are often inconspicuous and slowmoving. Inexperienced juveniles of many raptor 

species experience high rates of mortality from 

collisions with vehicles (Trombulak and Frissell 2000). 

Grouse are particularly susceptible to collision 

mortality during the spring because they often fly to 

and from leks near the ground. Also, higher CBNGrelated traffic volumes on existing paved roads would 

result in higher mortality rates for reptiles that seek out 

roads for thermal cooling and heating (Vestjens 1973). 
CHAPTER 4

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Direct mortality from vehicle collisions would be 

expected to increase for all wildlife along both new 

and existing roads used for CBNG exploration and 

well construction and maintenance (Groot et al. 1996). 

Collision mortality would be most injurious to small 

and declining populations with limited distribution. 

Direct impacts from collision and crushing would 

continue for the duration of the project along roads 

until they are successfully closed and reclaimed. Some 

additional mortality would continue indefinitely 

because some new CBNG roads would not be closed 

and reclaimed.

Additional direct impacts would occur on private lands 

because state and federal lease stipulations are 

recommended but not required. State requirements 

would lessen direct impacts on state lands compared to 

private lands. These impacts include greater potential 

loss of riparian vegetation and other floodplain habitats 

valuable for wildlife, abandonment of raptor nests 

because of direct habitat loss and disturbance and

habitat loss for a wide range of species that occupy 

prairie dog towns. 

Table 4-68 indicates the relative level of vulnerability 

of different representative types of wildlife to direct 

and indirect impacts. Most indirect impacts on wildlife 

would occur during all CBNG phases on BLM, state

and private lands. The duration of effects would 

correspond with the duration of each phase and the 

intensity of activity during that phase. The relative 

magnitude of impacts would be directly related to the 

nature and extent of activities associated with each 

phase of CBNG development. Some indirect effects 

would persist beyond abandonment because continued 

human use of some CBNG and user-created roads that 

are not closed and reclaimed (USDI and USDA 2001).

While roads do not affect all species and ecosystems 

equally, the overall presence of roads correlates highly 

with changes in species composition, population size

and hydrologic and geomorphic processes that shape 

aquatic and riparian systems. All types of roads affect 

terrestrial species in several ways: 

(1) increased mortality from road construction, 

(2) increased mortality from collisions with vehicles, 

(3) modification of animal behavior, (4) alteration of 

the physical environment, (5) alteration of the 

chemical environment, (6) spread of exotic species and

(7) increased alteration and use of habitats by humans 

(Trombulak and Frissell 2000).

CBNG-developed roads and two-track trails would 

provide access into previously roadless areas and 

would result in additional user-created roads and trails 

branching off from CBNG roads (USDI and USDA 

2001). Access to most CBNG roads on private lands 

would be restricted by the surface owner. Public access 

would be restricted on most CBNG roads on BLMadministered surfaces through the use of fences and 

gates. This is expected to be successful in limiting the 

majority of public access. However, the open rolling 

nature of the terrain in the project area combined with 

the proliferation of four-wheel-drive trucks and allterrain vehicles would allow the creation of usercreated roads (USDI and USDA 2001). This would 

cause additional road-related direct and indirect 

impacts over large open areas because of the great 

sight distances in central and southeastern Montana.

Some CBNG roads would continue to be used by the 

public throughout the entire production phase because 

road closures are difficult to implement and enforce in 

flat to rolling short grass prairie habitat. This continued 

use would hamper reclamation efforts on some CBNG 

roads while others would remain open to the public by 

choice. Some portion of CBNG roads, as well as usercreated roads, would become permanent, with all of 

the associated direct and indirect impacts on wildlife 

and habitat.

Human use of all types of roads is a source of stress for 

many species (Knick et al. 2003). Roads also may 

affect an animal’s reproductive success (Gutzwiller 

1991). Golden eagles prefer to nest away from human 

disturbances, including roads and have reduced nesting 

success in nests located closer to roads than in nests 

farther from roads (Fernandez 2001). Chronic 

physiological stress on wildlife can result in increased 

sickness, a decrease in individual productivity (Knight 

and Cole 1991 Anderson and Keith 1980, Yarmoloy et 

al. 1988) and eventually result in population declines 

(Anderson and Keith 1980).

The increased access provided by both CBNG and 

user-created trails and roads over the span of all CBNG 

phases and beyond would result in additional legal and 

illegal harvest of game animals (Cole et al. 1997), 

recreation shooting of animals such as prairie dogs or

other species (Ingles 1965) and chasing and harassing 

of animals (Posewitz 1999, USDI and USDA 2001). 

Human-caused fires are likely to increase in areas not 

regularly accessed by the general public before CBNG 

and user-created roads were present. 

Indirect impacts of road development and use as would 

occur during exploration, development and production 

on wildlife and wildlife habitat have been well 

documented for a variety of natural resource extraction 

and development projects (Trombulak and Frissell 

2000, USDI and USDA 2000, Wisdom et al. 2000, 

Braun et al. no date listed). Indirect impacts of CBNG 

exploration and development on certain species of 

wildlife more sensitive to development and human 

disturbance would occur over much larger areas than 

the direct impacts.
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The Oil and Gas Development on the Southern UTE 

EIS (BLM 2002c) suggested human presence 

associated with exploration and development of oil and 

gas wells disturbed wildlife at distances up to 1/2 mile

and that operation and maintenance activities caused 

disturbance within 1/4 mile of wells and roads. The 

disturbance results both from the presence of people 

and from the noise associated with exploration and 

development. There are numerous studies documenting 

wildlife avoidance of roads and facilities and wildlife 

disturbance at distances of 1,650 feet (Madsen 1985), 

6,600 feet (Van der Zande et al. 1980) and as far as 

two miles or more for sage-grouse (summarized in 

Connelly et al. 2000) and raptors (Fyfe and Olendorff 

1976). 

Impacts to mule deer habitat use, movements and

populations are also a concern and have recently been 

examined by the Wyoming Cooperative Fish and 

Wildlife Research Unit in the Pinedale Anticline 

Project area in western Wyoming. This area has been 

identified as important winter range for mule deer and

concerns exist regarding potential effects conventional 

gas field development may have on the deer 

population. Conclusions in the most recent progress 

report show there have been considerable interruptions 

in movement patterns and shifts in habitat areas used, 

resulting in population declines of approximately 48 

percent in the wintering deer population. While no 

studies have been done in Montana evaluating CBNG 

impacts on mule deer movements and habitat use, it is 

reasonable to conclude mule deer in southern Montana, 

which do not exhibit migratory behavior, would be 

impacted by CBNG development. The types of 

impacts would be similar to those identified in the 

Wyoming study. 

Elk avoidance of roads has been documented in many 

studies throughout the West (Lyon 1979 and 1983, 

Perry and Overly 1976, Rost and Bailey 1979, Ward et 

al. 1973). Human presence along roads displaces big 

game species such as elk as well as other species 

sensitive to human presence from otherwise useable 

habitat, especially during the day. Elk in Montana 

prefer spring feeding sites away from visible roads 

(Grover and Thompson 1986) and both elk and mule 

deer in Colorado prefer areas greater than 660 feet 

from roads during the winter (Rost and Bailey 1979). 

Lyon (1983) studied the effects of roads on elk 

distribution and habitat use. He reported that within 

blocks of available elk habitat, road densities of only 

two miles of primitive (undeveloped) road open to 

vehicle traffic per square mile resulted in elk 

displacement from over 50 percent of the available 

habitat in the areas with roads present. The avoidance 

was due to human disturbance and the resulting lack of 

security for the elk. This type of disturbance would be 

greatest in open country such as much of the Planning 

Area where line-of-sight distances are relatively long 

and escape cover is often limited.

Displacement from habitat because of roads, CBNG 

facilities and human disturbance may result in any of a 

number of individual and population level impacts on 

wildlife (Trombulak and Frissell 2000, Wisdom et al. 

2000). These include stress, disruption of normal 

foraging and reproductive habits, abandonment of 

unique habitat features and increased energy 

expenditure. These factors contribute to reduced overwinter survival for individuals, poor condition entering 

the breeding season, reduced reproductive success and 

recruitment and eventually population declines 

(Trombulak and Frissell 2000, Wisdom et al. 2000). 

For example, many raptor species that nest along 

prominent landscape features such as cliffs in open 

country are easily disturbed during the nesting season, 

often resulting in nest abandonment (Fyfe and 

Olendorf 1976).

Overhead power lines constructed for production wells 

pose problems for a variety of wildlife species. Raptors 

sage-grouse and other species of birds occasionally 

collide with power lines, especially during periods of 

relatively poor visibility. Overhead power lines can 

benefit some raptors in open country by providing 

hunting perches. However, the additional perches also 

result in local population declines in prey species. For 

example, overhead power lines constructed in the 

vicinity of grouse leks and wintering areas can 

substantially increase predation rates on grouse. The 

risk of electrocution on federal and state lands is small 

because the BLM and State require power lines and 

poles be constructed to standards that would avoid 

raptor electrocution. Raptor and sage-grouse collisions 

with power lines have also been noted throughout the 

west including eastern Montana. Bevanger (1998) 

noted growing empirical evidence of the high risk of 

collision with powerlines for birds with heavy bodies 

and small wings that are characterized by rapid flight. 

These birds, including grouse, have a restricted ability 

to react swiftly to unexpected obstacles, such as 

powerlines (Bevanger 1998).

Another wildlife disturbance factor associated with 

CBNG exploration, development and operation is 

noise. The highest noise levels and greatest impacts 

would be expected during exploration and 

development, with lower noise levels during 

production operations. Noise levels would be similar 

on BLM and other lands. Animals react differently to 

noises, but noise is especially troublesome for birds. 

Many neotropical birds that occur in the project area, 

such as western meadowlark, lark bunting, grasshopper 

sparrow, vesper sparrow, Brewer’s sparrow, burrowing 
4-266

TABLE 4- 68
CHAPTER 4

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owl and short-eared owl, may be affected by energy 

development. There is little research identifying 

impacts of energy development to these 

sagebrush/grassland migratory species. However, there 

is research documenting negative impacts of noise to 

many species. Most species are vulnerable to activities 

that reduce or fragment sagebrush/grassland habitats. 

Direct impacts include destruction of nests during 

construction of roads, pipelines, power lines (buried 

and overhead), well pads and retention ponds; and 

displacement of birds from the construction area.

Increased mortality of migratory birds would be likely 

from increased road traffic associated with operation 

and maintenance of these facilities.

Indirect impacts would include physical disturbances 

and physiological stresses on migratory birds from 

increased human activity in the area, as well as

increased habitat fragmentation leading to reduced 

nesting for species that require large habitat areas. 

CBNG activities that reduce or fragment 

sagebrush/grassland habitat would impact nesting 

migratory birds in the project area. Although average 

territory size for grasshopper sparrows, for example, is 

small (less than 2 hectares), they are area-sensitive and 

prefer large grassland areas over small areas (Dechant 

et al. 1998). 

When construction is completed and human presence 

has decreased, some displaced migratory birds would

return to suitable habitats. 

Male neotropical migrant birds that breed in short 

grass prairie, sagebrush and riparian communities use 

songs to establish and defend breeding territories and 

attract females. Noise interferes with this ability, with 

the level of interference related to the volume and 

frequency of the noise (Luckenbach 1975, Luckenbach 

1978, Memphis State University 1971, Weinstein 

1978). Other noise-related problems for birds around 

CBNG exploration and production wells and 

compressors include interference with the ability to 

recognize warning calls and calls by juveniles, both of 

which can result in higher predation rates. The area of 

disturbance would vary by species and CBNG activity. 

Producing wells would be relatively quiet once 

production is underway. Compressors would be limited 

to 50 decibels at a distance of 1/4 mile. 

Stipulations prohibit surface occupancy in riparian 

areas and on floodplains of major rivers. However, 

they do not prohibit crossing of streams or construction 

of roads through riparian areas. Roads constructed 

through riparian areas and other forest and shrub 

stands for CBNG development and operation create 

edge effects and alter the physical environment 

(Trombulak and Frissell 2000). Roads create drier 

conditions in the vicinity of the road, thereby altering 

habitat for many species. In grassland and shrubland 

habitats, trails and roads create edge habitat for 

predators and reduce patch size of remaining habitat 

for area-sensitive species (USDI and USDA 2001, 

Ingelfinger 2001). Swihart and Slade (1984) found 

prairie voles (Microtus ochrogaster), which occur in 

the Planning Area, were reluctant to cross tire tracks 

running through an open field. Reluctance to cross 

narrow gravel roads has also been observed in whitefooted mice (Peromyscus leucopus), which also occur 

in the Planning Area and many other rodent species 

(Mader 1984, Merriam et al. 1989, Oxley et al. 1974). 

Consequently, roads can function as barriers to 

population dispersal and movement for small 

mammals that occur in the Planning Area. 

Many amphibians annual life cycles require migration 

between habitats with different ecological properties. 

These species’ populations depend on dispersal 

connections and landscape links (Gibbs 1998). Simple 

linear structures such as roads of all types can act as 

physical and psychological barriers for amphibian 

movement (Mader 1984, Gibbs 1998). Furthermore, 

motorized off-highway travel may disrupt reptile and 

amphibian habitat to the point where it becomes 

unusable (Busack and Bury 1974). Pronghorns and 

mountain lions have also demonstrated reluctance to 

crossing roads (Bruns 1977, Van Dyke et al. 1986). 

Noxious weeds and exotic plants rapidly colonize 

disturbed sites, prevent native species from being reestablished following ground disturbance, spread into 

undisturbed areas reducing habitat value on additional 

lands and provide very poor quality wildlife habitat or 

forage. Mitigation measures discussed under 

vegetation are intended to avoid, reduce and control 

new infestations of noxious weeds through a variety of 

actions. Consistent and successful application of these 

mitigation measures would reduce potential habitat 

degradation. However, use of chemicals to control 

noxious weeds usually also kills non-target beneficial 

native plants, contributing to habitat loss. 

Roads are sources of fine sediment that can enter 

wetlands and intermittent and perennial drainages, 

especially following thunderstorms. Effects include 

increased turbidity (Reid and Dunne 1984), smothering 

wetland vegetation and degradation of habitat for 

amphibians and other aquatic life (Newcombe and 

Jensen 1996).

There are no apparent differences between indirect 

impacts on wildlife on BLM-administered and state 

lands. Impacts on private lands may be more 

substantial because stipulations and mitigation

measures are not mandated on private lands. 
CHAPTER 4

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Species of Concern

Species of concern include federally listed T&E and 

candidate species; Montana species of concern; BLM 

species of concern, and MNHP species of concern. For 

the State of Montana species of concern, this document 

addresses only those listed as category S1, which are 

species of extreme rarity or species for which some 

factor of its biology makes it especially vulnerable to 

extinction. Chapter 3 of the EIS describes and lists all 

special-status species.

As discussed in the Species of Concern section of 

Chapter 3 in this EIS, there are 9 federally listed 

threatened, endangered and proposed species; and 

3 federal candidate species. In accordance with the 

ESA, listed wildlife must be protected from possible 

impact by oil and gas and CBNG development on all 

lands. ESA protected plants are not protected on 

private lands. Additionally, there are many species 

classified as “species of special concern” by the 

Montana BLM and Montana Natural Heritage program 

(MNHP). By policy, BLM management cannot impact 

these species in a way that may cause further declines 

in the species’ population status. These include 68 

plant, 16 mammal, 9 herptile and 22 bird species and

are listed by the state and BLM. This section will 

address federally listed wildlife species protected 

under the ESA. General recommendations for other 

species of concern wildlife species can be found within 

the general Wildlife impact sections. Federally listed 

species are discussed individually because of the need 

for species-specific mitigation measures to avoid 

extensive impacts. Conclusions are summarized after 

all of the species are discussed.

For sensitive species, displacement from important 

habitat features is often effectively equal to loss of 

habitat for the individuals that occupied that habitat. 

Wildlife cannot generally just move to unoccupied 

habitat in response to disturbance and survive there, as

other suitable habitat is occupied by other individuals 

of the same species or by similar species using the 

available resources. 

Federally Listed Species

Mountain Plover

Mountain plover are most susceptible to disturbance 

during the nesting season, which occurs between midApril and early July. Construction activity and 

operations and maintenance could disturb the 

nesting/courting birds during this period. Noise and the 

presence of humans and equipment would be the main 

causes of disturbance. The absence of stipulations to 

protect mountain plover nesting areas (prairie dog

towns smaller than 80 acres) would result in impacts 

on this species if exploration or development occurs in 

or near occupied nesting habitat. Prairie dog towns 

often are located on flat, topographically low areas.

Interior Least Tern

As with mountain plover, this species is susceptible to

disturbance during the nesting period. 

Gray Wolf

Roads and the presence of humans would increase the 

threat from shooting, either on purpose or accidental 

(when mistaken for a coyote). The potential density of 

roads in occupied wolf areas could force wolves from 

occupied areas and could increase stress on wolves and 

result in the loss of some individuals. 

Canada Lynx

Canada lynx would be expected mainly in western and 

south-central Montana, where high-elevation, dense, 

old-growth forests are most likely to be found. 

Although possible, exploration and development of 

CBNG are not expected to occur in these habitats. 

Therefore, there would be no impacts to Canada lynx.

Black-Footed Ferret

Black-footed ferrets are exclusively found associated 

with their main prey species: prairie dogs. Prairie dogs 

are found throughout the project area. Any activity 

affecting prairie dog colonies has the potential to 

impact the ferret. Prairie dog colonies are frequently 

located on level to slightly sloping ground. Two BLM 

leasing stipulations address black-footed ferret

concerns. The first states that exploration in prairie dog 

colonies within potential black-footed ferret 

reintroduction areas comply with the Draft Guidelines 

for Oil and Gas Activities in Prairie Dog Ecosystems 

Managed for Black-footed Ferret Recovery (FWS 

1988, BLM 1992). If these guidelines are accepted, 

they specify that conditions of approval depend on the 

type and duration of the proposed activity, proximity to 

occupied ferret habitat and other site-specific 

conditions. Exceptions or waivers of this stipulation 

may be granted if the Montana Black-Footed Ferret 

Coordination Committee determines that the proposed 

activity would have no disagreeable impacts on ferret 

reintroduction or recovery. The status of the Fort 

Belknap population allows them to be treated as a 

proposed species, which may require a conference with 

FWS if impacts are expected in the vicinity of the 

reservation.

The second stipulation requires that all prairie dog

colonies or complexes greater than 80 acres in size be 

surveyed for black-footed ferret absence or presence 

prior to ground disturbance. Prairie dog complexes 
CHAPTER 4

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may consist of several smaller colonies located near 

one another. The results of the survey determine if 

restrictions or denial of use are appropriate for the site. 

Permits issued by MBOGC do not have the same 

stated requirements for protection of prairie dog towns 

of certain sizes; however, the ESAs protection of listed 

wildlife does apply to state and private land. Operators 

are prohibited from causing harm to the ferret. As 

appropriate, state leases would include a survey 

stipulation or contact MFWP stipulation for species of 

concern.

Implementation of stipulations in potential and 

occupied habitat would avoid impacts to the ferret on 

BLM-administered surface. 

Grizzly Bear

Threats to grizzly bears mainly result from human-bear 

interactions, which occasionally end in the death of the 

grizzly bear. If exploration moves into sparsely settled 

areas or previously roadless areas within grizzly bear 

range, the possibility of bear-human interaction 

increases. 

Federal Candidate Species

One candidate species may potentially be found in the 

project area: the black-tailed prairie dog. Although not 

subject to the substantive or procedural provisions of 

the ESA, FWS encourages no action be taken that 

could impact candidate species and contribute to the 

need to list the species. The state also has a policy that 

the state should take no action that could contribute to 

these species being listed. The USFWS issued a “not 

warranted” finding for black-tailed prairie dogs in 

2004.

Black-Tailed Prairie Dog

As discussed under black-footed ferret above, BLM 

has stipulations governing activities that could impact 

black-tailed prairie dog towns larger than 80 acres if 

ferrets are found to be present. However, these 

protections do not apply if the ferret is not present. The 

MFWP through a working group composed of state, 

federal and private individuals is developing a Prairie 

Dog Conservation Plan to address how to avoid 

continuing impacts, which are resulting in population 

declines. There are no special protective measures 

being implemented by the state or BLM at this time, 

although an evaluation including associated impacts to 

other listed species, in order to identify measures to 

avoid impacts is required. Construction of CBNG 

exploration and production wells on all land 

ownerships is expected to impact black-tailed prairie 

dog towns. 

BLM, USFS and Montana Species of 

Concern

Under all alternatives, the variety of life forms and the 

large number of species of concern, the lack of 

specificity of project locations and the wide variation 

in habitat used by these species preclude the ability to 

identify specific impacts to each individual species of 

concern. Exploration and development of CBNG wells 

would result in a variety of direct and indirect impacts 

to species of concern. Specific impacts would depend 

on the species, the amount and type of habitat removed

and the nature and period of disturbance. Leasing 

stipulations as discussed above and in the Wildlife

section would offset or offer some protection to 

federally listed species. However, there are no 

stipulations for most species of concern.

Alternative A presents a discussion of impacts to all 

wildlife species, of which species of concern are a 

subset. That discussion is not repeated here and the 

reader should refer to the Wildlife section for an 

understanding of impacts to wildlife species of 

concern. Some of these species are particularly 

vulnerable because of their scarcity or narrow habitat 

niche.

Guidelines recently developed by Connelly et al. 

(2000) to manage sage-grouse populations and their 

habitat indicate that the stipulations stated above that 

are intended to avoid impacts on sage-grouse leks and

nesting areas during exploration are not adequate to do 

so. Sage-grouse are extremely sensitive to human 

disturbance and habitat alteration and breeding 

populations have declined dramatically throughout 

much of their range (Connelly and Braun 1997) 

including south-central and southeastern Montana

(Eustace 2001). MFWP has been monitoring certain 

sage-grouse leks in south-central Montana since the 

early 1980s. There has been an approximate 50 percent 

reduction in the number of these active leks since the 

monitoring began. Eustace attributes this decline to 

habitat loss and human disturbance and stated that he 

believes similar declines have occurred in other 

portions of Montana. Connelly et al. (2000) indicate 

energy-related facilities should be located at least two

miles from sage-grouse leks. Connelly et al. further 

note sage-grouse populations display four types of 

migratory patterns: 1) distinct winter, breeding and

summer areas; 2) distinct summer areas and integrated 

winter and breeding areas; 3) distinct winter areas and 

integrated breeding and summer areas; and 4) nonmigratory populations. Furthermore, recent studies in 

eastern Idaho have found that sage-grouse wintering 

areas may vary considerably from year to year 

depending on snow accumulation (Kemner and Lowe 

2002). 
CHAPTER 4

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Avoiding impacts on sage-grouse requires protecting 

the integrity of all seasonal ranges. Average distances 

between leks and nests vary from 0.7 to 3.9 miles 

(Autenreith 1981, Wakkinen et al. 1992, Fischer 1994, 

Hanf et al. 1994, Lyon 2000) and movements between 

seasonal ranges may exceed 45 miles (Dalke et al. 

1963, Connelly et al. 1988). Furthermore, sage-grouse

have high fidelity to all seasonal ranges (Keister and 

Willis 1986, Fischer et al. 1993). Females return to the 

same area to nest each year (Fischer et al. 1993) and 

may nest within 660 feet of their previous year’s nest 

(Gates 1983). However, other studies by Lyon 2000, 

Fischer et al. 1993 and Berry and Eng 1985 found 

average distances of 683 meters (2,240 feet), 740 

meters (2,427 feet) and 552 meters (1,811 feet), 

respectively. Therefore, while important, protecting a 

1/4-mile (1,320 feet) radius area around leks as 

specified in the stipulations, may be inadequate to 

avoid impacts on displaying and nesting birds. 

Furthermore, this stipulation does not provide 

sufficient protection of the breeding area or any 

wintering areas. This stipulation is not adequate to 

avoid all the impacts on sage-grouse from CBNG 

activities. Sage-grouse would be impacted by CBNG 

activities that occur within two miles of sage-grouse

leks or within winter range.

Elevated noise levels might interfere with the ability of 

female sage-grouse to hear the booming of cock sagegrouse on the lek (USFWS 2005b). This might result 

in reduced lek attendance and reproductive success 

near CBNG locations, particularly where compressors 

that produce relatively loud noise levels are present. 

Researchers at University of California, Davis, are 

currently conducting a study on the effects of noise 

from CBNG development on sage-grouse in Wyoming 

(personal communication, G. Patricelli, 2005). Once 

complete, this study should provide additional 

information on the effects of noise on these birds. 

Montana’s Comprehensive Fish and Wildlife 

Conservation Strategy identifies the need to quantify 

impacts of energy development and determine ways to 

reduce, eliminate, or mitigate negative effects (MFWP, 

2005d). Recent and ongoing research has focused on 

these issues. 

In a recent research study conducted by Holloran and 

Anderson from the University of Wyoming, findings 

suggest natural gas development causes displacement 

of male sage-grouse from lek sites, ultimately 

contributing to localized sage-grouse extirpations, with 

negative, but less severe, influences on regional 

population levels (Holloran and Anderson 2004, 

Holloran 2005). Three levels of natural gas well 

development were evaluated in the study. Leks with 

fewer than 5 wells within the 5-km (3.2 miles) radius 

buffer were considered lightly impacted (control leks); 

leks with 5 to 15 wells within 5 km were moderately 

impacted; and leks with more than 15 wells within 5 

km were heavily impacted. On heavily impacted leks, 

the maximum number of males declined by 51 percent 

from the year before impact. Furthermore, the 

maximum number of males on three heavily impacted 

leks situated centrally within the developing field 

declined 89 percent and two of the three leks were 

essentially inactive in 2004. 

At a regional level, the number of strutting males 

counted on leks declined annually by an average of 

13 percent (Holloran 2005). The study also indicated 

that female sage-grouse avoided nesting near the 

infrastructure of natural gas fields and natural gas 

related impacts negatively influenced female 

population growth. While this study was conducted in 

a conventional natural gas development field and not 

in CBNG areas, the types of impacts are expected to be 

similar.

Habitat fragmentation negatively impacts population 

persistence, both short and long term, with more 

fragmentation increasing habitat isolation and possibly 

changing population response to habitat modification

(Patten et al. 2005). Fuhlendorf and others (2002) 

noted that large-scale patterns of land use and 

fragmentation have been associated with the decline of 

many imperiled wildlife populations. Their study of 

scale-dependent relationships between landscape 

structure and change, as well as long-term population 

trends for lesser prairie-chicken populations in the 

southern Great Plains, indicated that modifications in 

landscape structure over the past several decades 

resulted in stronger relationships with lesser prairiechicken population dynamics than current landscape 

structure. Wisdom and others (2002) indicated the 

sage-grouse has been extirpated from five states and 

one province. Breeding populations have declined an 

average of 35 percent since 1985, due to a variety of 

detrimental land uses. These studies suggest that local 

populations have to be viewed at a landscape-level. 

Future conservation efforts should address effects of 

fragmentation on natural populations, including 

dispersal, colonization and extinction patterns 

(Fuhlendorf et al. 2002, Patten et al. 2005, Wisdom et 

al. 2002).

Beginning in 2003, Montana and Wyoming BLM have 

worked cooperatively with the University of Montana 

and other partners to determine the potential impacts of 

CBNG development in the Powder River Basin. The 

research being conducted has evolved into three phases 

that are expected to answer management questions 

about development impacts on sage-grouse and 

effectiveness of BLM mitigation measures. Final 
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reports are scheduled to be completed during January 

2007 and January 2008.

In 2006, Dr. David E. Naugle, associated with the 

University of Montana and his researchers used 

satellite imagery on a landscape level to identify 

priority habitats for sage-grouse in the PRB. This 

information identified areas of high value sage-grouse 

habitats. This mapping used several components, 

including roughness, sagebrush coverage 

(height/abundance) and distance from conifers. In 

general, Dr. Naugle determined suitable long-term 

sage-grouse habitat must contain a minimum of 

1,000 contiguous acres of sagebrush and must be at 

least 400 meters from visible conifers. Dr. Naugle’s 

findings showed that sage-grouse avoided disturbance 

associated with CBNG development. Males on leks 

within areas of heavy CBNG development declined 

dramatically, while leks on the edge of development 

had increased numbers of males (Naugle, et al 2007). 

This increase is interpreted as an indication that those 

males previously using leks within areas of 

development were displaced to leks on the edge of 

disturbance. Leks outside of areas of disturbance 

followed the regional trend. 

While the aforementioned studies provided compelling 

evidence of impacts, long-term studies in the Pinedale 

Anticline Project Area gave the most complete picture 

of cumulative impacts of energy development to sagegrouse populations. Lyon and Anderson (2003) 

showed that early in the development process, nest 

sites were farther from disturbed leks than from 

undisturbed leks, that nest initiation rate for females 

from disturbed leks was 24% lower than for birds 

breeding on undisturbed leks, and that 26% fewer 

females from disturbed leks initiated nests in 

consecutive years. As development of the Pinedale 

Anticline progressed, Holloran (2005) reported that 

adult female sage-grouse remained in traditional 

nesting areas regardless of increasing levels of 

development, but yearling females that had not yet 

imprinted on habitats inside the gas field avoided 

development by nesting farther from main haul roads. 

Kaiser (2006) and Holloran et al. (2007) later 

confirmed that yearling females avoided infrastructure 

when selecting nest sites and that yearling males that 

avoided leks inside of development were displaced to 

those nearer the periphery of the gas field. Recruitment 

of males to leks also declined as distance within the 

external limit of development increased, indicating the 

likelihood of lek loss near the center of development.

Perhaps the most important finding from studies in the 

Pinedale Anticline was that sage-grouse declines are at 

least partially explained by lower survival of female 

sage-grouse, and that impacts to survival resulted in a 

true population-level decline (Holloran 2005). The 

population-level decline observed in sage-grouse 

(Holloran 2005) is similar to that observed in Kansas 

in the Lesser Prairie-chicken (Tympanuchus 

pallidicinctus) (Hagan 2003), a federally threatened 

species that also avoided otherwise suitable sandsagebrush (Artemisia filifolia) habitats proximal to oil 

and gas development (Pitman et al. 2005, Johnson et 

al. 2006). High site fidelity but low survival of adult 

sage-grouse combined with lek avoidance by younger 

birds (Kaiser 2006, Holloran et al. 2007) resulted in a 

time lag of 3-4 years between the onset of development 

activities and lek loss (Holloran 2005). The time lag 

observed by Holloran (2005) in the Pindeale Anticline 

matched that for leks that became inactive 3-4 years 

following intensive coal bed natural gas development 

in the Powder River Basin (Walker et al. 2007).

Overhead power lines pose several problems for sagegrouse. Sage-grouse occasionally collide with power 

lines, especially during periods of relatively poor 

visibility, such as flying to and from the leks. 

Overhead power lines provide hunting perches for 

raptors. Predation rates on sage-grouse increase 

dramatically when these lines are located in the 

vicinity of sage-grouse leks and wintering areas, 

resulting in population declines (Connelly et al. 2000, 

Milodrgovich 2001, Braun et al. no date listed). 

As discussed in the Hydrological Resources section, 

surface water bodies would not be impacted directly 

from groundwater withdrawal due to the depth and 

confined nature of the individual coal seams. In the 

unlikely event that there is a very localized connection 

between a spring-fed stream and groundwater 

withdrawals, effects on wildlife and habitat would 

include drying of springs and reduced flow and 

duration in intermittent and small perennial drainages. 

Sage-grouse could be severely impacted, as broods 

spend much of July and August in more mesic sites as 

sagebrush habitats desiccate (Gill 1965, Savage 1969, 

Connelly and Markham 1983, Fischer et al. 1998). 

Reduced availability of mesic sites would reduce sagegrouse brood survival and unfavorably affect 

populations (Connelly et al. 2000).

Bald Eagle

Bald eagles are sensitive to human presence. Based on 

the assumptions listed in the introduction to the 

Wildlife section, protection of nests and nesting habitat 

should prevent eagles from abandoning traditional 

nesting sites in the project area, but periodic or 

complete abandonment of non-nesting habitat may 

occur depending on the level of human use and noise. 

Above-ground transmission facilities could result in 

the death of some bald eagles because of electrocution. 
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However, the risk of electrocution on federal and state 

lands is small because the BLM and State require 

power lines and poles be constructed to standards that 

would avoid raptor electrocution (Table MIN-5). 

Power lines also pose strike hazards for bald eagles, 

especially near perennial rivers and water bodies that 

support fish and waterfowl. Removal of large trees in 

wintering areas, particularly at established roost sites, 

would also displace bald eagles by removing perch and 

roost sites.

Crow Reservation

Off reservation CBNG development would not 

indirectly impact wildlife on the Crow Reservation. 

Northern Cheyenne Reservation

There would be fewer impacts to wildlife on the 

reservation resulting from off-reservation CBNG 

development, as the buffer between development and 

the reservation should mitigate most impacts.. 

Mitigation 

Agency-applied mitigation measures for BLM and 

state lands related to natural resources are presented in 

Chapter 2 and Table MIN-5 of the Minerals Appendix. 

Agency-applied measures would be implemented as 

needed and enforced during all CBNG phases. 

Agency-applied mitigation measures are intended to 

compensate after-the-fact for some impacts not 

avoided through standard lease stipulations. Residual 

impacts are those that remain after implementation of 

mitigation measures. 

BLM would include and enforce agency applied 

mitigation (described in Chapter 2 and the Minerals 

Appendix) through application of standard lease 

stipulations during the site-specific plan approval 

stage. Measures to further avoid or reduce impacts in 

addition to those included at the plan approval stage 

may be recommended. The state would apply 

additional mitigation measures on a case-by-case basis 

through the use of field rules. 

Species of Concern Mitigation Measures

Bald Eagle

Before construction begins, a wildlife biologist would 

survey the construction zone in a 0.5-mile radius for 

bald eagles and bald eagle nests and identify any 

locations found. The use of no surface occupancy 

within 0.5 miles of known nests would reduce but not 

eliminate potential impacts to nesting, foraging and

roosting bald eagles.

Mountain Plover

Surveys would be made within suitable mountain 

plover habitat within the roadway corridor and pad 

sites prior to exploration. FWS survey protocol for 

mountain plover would be followed. See the Wildlife 

Appendix Biological Assessment for Mountain Plover 

Survey Guidelines. This includes surveying from May 

1 through June 15 for presence or absence on potential 

sites. Exploration and Construction would be avoided 

in these areas during this time period to assure that 

potential nesting mountain plovers are not prevented 

from setting up territories as a result of the presence of 

equipment and humans.

Interior Least Tern

The likelihood of encountering least terns within the 

SEIS area is remote. Should nest tern locations be 

identified, exploratory drilling and construction sites 

would be identified and appropriate surveys would be 

conducted for this species. Surface occupancy and use

is prohibited within 1/4 mile of wetlands used by 

nesting interior least terns during exploration. This 

stipulation would minimize impacts to interior least 

tern. Occupied wetlands and water levels would be 

protected in all phases of drilling and construction and 

no discharge of produced water into occupied wetlands 

would be permitted. 

Gray Wolf

Prior to construction in potential gray wolf habitat, 

surveys would include specific searches for this 

animal, occupied dens, or scat. The corridor would be 

surveyed in the spring, prior to construction, by a 

wildlife biologist for scat. If scat is found, the site 

would be surrounded by a buffer zone recommended 

through consultation with an FWS biologist. If wolves 

or other wolf indicators are found, FWS would be 

consulted and proper protocols followed.

Canada Lynx

Any construction areas or drilling pads located in high 

elevation, old growth forested areas considered 

potential Canada Lynx habitat, would be surveyed 

prior to construction for scat and individuals following 

established protocols. If found, the site would be 

avoided and surrounded by a buffer zone 

recommended by FWS biologists.

Black-Footed Ferret

Implementation of stipulations on occupied habitat 

would avoid impacts to the ferret on BLMadministered surface. 
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Grizzly Bear

Garbage and other human refuse would be removed 

from drilling and construction sites on a daily basis in 

potential bear habitat to avoid attracting bears. Surveys 

for scat and other sign of grizzly bears in remote, 

sparsely roaded areas would be conducted prior to 

construction. If found, protocol would be established 

after consultation with FWS biologists.

Black-Tailed Prairie Dog

Development of mitigation measures for the prairie 

dog depends upon the recommendations developed in 

the Conservation Plan for Black-Tailed and WhiteTailed Prairie Dogs in Montana (January 2002). This 

plan would address how to avoid continuing impacts. 

Conclusions

If a state or private CBNG project triggers a federally 

related action, the FWS would need to be consulted for 

federally protected species, by the Federal agency. 

Stipulations would avoid some impacts for some

species. However, these stipulations would not be 

100 percent effective for all species because of limits 

on available biological information, some stipulations 

do not apply to operations and the stipulations are not 

meant to eliminate all negative impacts. The potential 

for impacts is relatively low under Alternative A 

compared to the other alternatives because of the 

limited number of CBNG wells. Mitigation measures

(Table MIN-5, Minerals Appendix) generally focus on 

vegetation reclamation and related efforts to reduce 

erosion and water pollution. Measures intended to 

reduce surface disturbance in sensitive habitats are to 

be implemented “to the extent practicable.” Therefore, 

it is likely some sensitive habitats and species could be 

directly impacted by CBNG development under 

Alternative A. The intent of reclamation, as identified 

in Miles City Field Office (MCFO) policy is to reestablish a vegetative cover on disturbed areas rather 

than to restore native plant communities as they 

existed prior to disturbance. Plant species diversity 

would be lower on reclaimed sites than before 

disturbance, reducing overall wildlife habitat values. 

Existing mitigation measures would not effectively 

compensate for impacts on wildlife.

Some wildlife species and habitat may be disturbed or 

lost during construction. Individual animals may be 

lost through collisions with vehicles and indirect 

impacts as described previously for general wildlife. 

Indirect impacts also could result in displacement or 

abandonment of habitat or to increased legal and 

illegal hunting pressure. Species of concern on all 

lands do not have the same level of protection as ESAprotected species. Therefore, some direct and indirect 

impacts on individuals or even populations within 

metapopulations would be expected. This alternative 

would have the least impact on all species because of 

the limited number of wells and (500 long-term acres) 

associated disturbances.

If habitat degradation is minimized, mitigation

measures applied and appropriate surveys conducted 

prior to construction, ensuring these species are not 

found within the project area and, if found, are 

buffered by suitable no construction zones and work 

restrictions, wildlife species would be affected but the 

impacts should be mitigatable. 

There could be some displacement of bald eagles in 

non-nesting habitat. Black-tailed prairie dogs would be 

impacted by this alternative on or adjacent to prairie

dog towns where CBNG development occurs. 

Species not federally protected may be impacted by 

habitat changes caused by vegetation removal, changes 

in vegetation species composition, increased access

because of more roads, increased noise levels and

conflicts with CBNG infrastructure and increased 

human pressure. Changes in stream or spring 

hydrology and increased SAR and salinity values in 

water and soil could also have adverse impacts.

Cumulative Impacts 

The cumulative impacts on wildlife resulting from the 

effects of Alternative A include the direct loss of 

wildlife habitat, habitat fragmentation and wildlife 

mortality from collisions. Noise and human presence 

would disturb wildlife species over large areas near 

developed well fields, causing local population 

declines for some species. This would be particularly 

problematic for sensitive species such as raptors, sagegrouse and other birds dependent on sagebrush 

habitats. 

Impacts from Wyoming CBNG development on wildlife 

and wildlife habitat would be similar to those described 

under Alternative A, but at a far larger scale. More than 

2.5 times as many CBNG wells may be developed in the 

Powder River basin of Wyoming than the 18,300 

considered under Alternatives B, C, D and E in 

Montana. The magnitude of direct and indirect 

Wyoming CBNG impacts on wildlife and wildlife 

habitat would be about 2.5 times greater than described 

for Alternatives B, C and D (described in the following 

sections). CBNG development in Wyoming would 

cumulatively impact many species in Montana. 

The increase in water volume at certain times has the 

potential to cover sandbars and other open areas. There 

would be potential cumulative impacts for bald eagles 

and interior least tern present in this river habitat, as 
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flow fluctuations and alterations in SAR values could 

affect the food chain these species rely on and because 

it may affect their nesting habitat. 

Cumulative impacts of other activities, including the 

Tongue River Railroad, conventional oil and gas, 

active coal mines and fires are expected to result in the 

long term loss of an additional 41,070 acres. Types of

indirect impacts on wildlife would be similar to those 

described above and would affect an area much larger 

than 37,000 acres. Some impacts on sensitive and 

protected species would be expected from 

development on this scale.

Alternative B—Emphasize Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

Generally, the same types of impacts on wildlife 

described for Alternative A would occur under 

Alternative B. However, Alternative B includes 

development or the drilling of 18,300 CBNG wells. 

This is about 20 times as many wells; miles of roads, 

pipelines and utility corridors and facilities and 

20 times more human activity than for Alternative A. It 

is important to recognize the development would take 

place over a 20-year period and the initiation of well 

development (20 times) would not occur all at once. 

However, production at any given well is expected to 

continue for 20 years so there would be substantial 

overlap between wells developed early and those 

developed later in the 40-year time frame between 

development of the first wells and closure of the last 

ones. Because of this level of CBNG development, 

Alternative B would have widespread ecosystem-level 

types of impacts on wildlife and wildlife habitat as 

discussed at length for Alternative A.

Virtually every wildlife species that occurs within 

CBNG development areas would be impacted to some 

degree, with sensitive species suffering the greatest 

impacts because of their already precarious status. For 

example, wintering and nesting sage-grouse and 

nesting golden eagles would be expected to suffer 

large-scale impacts. It is likely that, at this scale of 

development, some species would become locally rare 

or vacate large areas. All of the wildlife groups listed 

in Table 4-68 would have a high probability of being 

impacted throughout the CBNG development area 

under Alternative B because of the scale of the 

development.

Table 4-66 in the Vegetation section notes the number 

of acres of direct impact (habitat loss) and the number 

of miles of roads, pipelines and utility corridors that 

would result from CBNG development under 

Alternatives B, C, D and E. Development under 

Alternative B would result in the direct short term loss 

of about 55,400 acres of wildlife habitat to well pads, 

roads (6,680 miles) and pipeline and utility corridors 

(20,679 miles). Long term impacts would persist on 

about 33,000 acres after reclamation of exploration 

disturbance. However, as noted for Alternative A, 

plant species diversity would be lower on reclaimed 

lands than before disturbance, resulting in reduced 

habitat value for many species and habitat 

fragmentation for some species. Additional vegetation 

would be disturbed by multiple exploration vehicles 

moving across the landscape searching for suitable 

locations to drill exploratory wells. Direct and indirect 

impacts on wildlife from this scale of development 

would be widespread.

The discussion of impacts for Alternative A indicated 

mule deer, elk, sage-grouse, raptors and other species 

are particularly sensitive to human disturbance 

associated with CBNG development and related roads. 

Not all wildlife species are as sensitive to roads and 

disturbance as these species. However, those that are 

the most sensitive often include species that are 

declining in numbers and distribution because of this 

sensitivity, such as sage-grouse and raptors, including 

ferruginous hawks (Buteo regalis). With respect to 

sage-grouse, recent research by Doherty, et. al. (2007) 

outlines the sensitivity of this species to CBNG 

development. CBNG development in Wyoming has 

displaced sage-grouse from crucial habitat and their 

population continues to decline as CBNG activity 

expands into previously undeveloped areas. These

impacts are also likely to occur in the Montana portion 

of the PRB, even when timing limitations and 

avoidance areas are applied as BMPs. Table 4-69 

provides estimates of the area of habitat within which 

species sensitive to disturbance and roads may be 

affected both within and around the perimeter of 

CBNG well fields. The table presents data on the size 

of areas which potentially are affected at both 1/2-mile 

and 2-mile perimeters around well fields (Fyfe and 

Olendorff 1976, Lyon 1983, Connelly et al. 2000). 

Table 4-69 assumes well field development would 

include 8, 16, or 24 wells per square mile and that each 

well field would include 200 wells. CBNG well 

development is projected to occur over a 20-year 

period with an average well life of 20 years. Therefore, 

the information presented in Table 4-69 represents the

maximum area of disturbance for sensitive wildlife 

species in year 20 when all wells would be developed 

and none closed. Approximately 44 percent of the 

wells and associated disturbance would be in place in 

year 5, 72 percent in year 10 and 87 percent in year 15. 

By year 20, indirect impacts of CBNG development 

would affect sensitive species of wildlife on between 

880,000 and 4.7 million acres. Sagebrush obligate song 

birds, which are suffering range-wide population 
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declines, are also sensitive to disturbance and habitat 

fragmentation. They avoid pipeline and road corridors 

even when the roads are unpaved and receive little use 

(Ingelfinger 2001). His research in Wyoming natural 

gas fields found that the density of sagebrush obligates 

including Brewer’s sparrow (Spizella breweri), sage 

sparrow (Amphispiza belli) and sage thrasher 

(Oreoscoptes montanus) were 

TABLE 4-69

AREA OF DIRECT IMPACTS AND INDIRECT WILDLIFE DISTURBANCE AND DISPLACEMENT1 WITHIN AND 

AROUND CBNG WELL FIELDS FOR MORE SENSITIVE WILDLIFE SPECIES FOR ALTERNATIVES B 

THROUGH G AND H

(ASSUMES 200 WELLS PER WELL FIELD, 8, 16, OR 24 WELLS PER SQUARE MILE2)

Indirectly Affected Area Within 1/2 Mile Indirectly Affected Area Within 2 Miles

Number of Wells 

Per Square Mile

Acres Per 

Well Field

Additional Area 

Affected Around 

Perimeter of Each 

Well Field

Total Affected Area 

Within Well Fields and 

Within 1/2 Mile of Well 

Field Perimeters3

Additional Area 

Affected Around 

Perimeter of Each 

Well Field

Total Affected Area Within 

Well Fields and Within 2 

Miles of Well Field 

Perimeters3

Acres Acres Acres Acres

Alternatives B Through F and H4--18,300 Wells and 91.5 Well Fields

8 16,000 7,040 2,108,160 35,840 4,743,360

16 8,000 5,120 1,200,480 28,160 3,308,640

24 5,312 4,352 884,256 25,152 2,787,456

Cumulative Impact of CBNG Development Only for Alternatives B Through F and H--26,500 Wells and 132.5 Well Fields

8 16,000 7,040 3,052,800 35,840 6,868,800

16 8,000 5,120 1,738,400 28,160 4,791,200

24 5,312 4,352 1,280,480 25,152 4,036,480

Alternative G--6,470 Wells and 32.4 Well Fields

8 16,000 7,040 746,496 35,840 1,679,616

16 8,000 5,120 425,088 28,160 1,171,584

24 5,312 4,352 313,114 25,152 987,034

Cumulative Impact of CBNG Development Only for Alternative G--14,670 Wells and 73.4 Well Fields

8 16,000 7,040 1,691,136 35,840 3,805,056

16 8,000 5,120 963,008 28,160 2,654,144

24 5,312 4,352 709,338 25,152 2,236,058

1

See text for discussion of individual and population level consequences of displacement.

2

A larger average number of wells per field would reduce the affected area. For example, fields averaging 1,000 wells per field and 8 wells per 

square mile would impact 1,738,061 acres instead of 2,108,160 acres.

3

Affected area around well fields assumes there is no overlap between affected areas of adjacent well fields. Overlap would reduce affected 

perimeter area.

4

Although Alternatives F and H include 75 fewer predicted wells than Alternatives B through E, the total area of indirect disturbance is only 

slightly less. Consequently, Alternatives F and H are considered to have the same amount of indirect disturbance as Alternatives B through E.
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reduced by 50 percent within 100 meters of lightly

traveled unpaved roads compared to densities in 

undisturbed sagebrush communities. Sage sparrow 

density along a natural gas pipeline route with no 

traffic was 64 percent lower within 100 meters of the 

route compared to densities in nearby undisturbed 

sagebrush. Ingelfinger (2001) attributed these declines 

to noise (along the roads), habitat fragmentation, edge 

avoidance and possibly inter-specific competition with 

horned larks, a species that forages along roads. At full 

development there would be 6,680 miles of new roads. 

Assuming no overlap, 100 meters on each side of these 

roads would include over 530,000 acres and additional 

effective habitat loss would occur along pipelines. 

These lands are included in the information presented 

in Table 4-69. 

Some additional direct and indirect impacts not 

described for Alternative A would be expected to 

occur under Alternative B because of the much greater 

scale of CBNG development. Prairie dog colonies tend 

to be located on relatively flat ground and often in 

valleys. Prairie dog towns also support much higher 

densities of birds and mammals and greater avian 

species richness than adjacent prairie (Agnew et al. 

1986). Various studies have reported 163 vertebrate 

species using black-tailed prairie dog colonies in 

Montana including several species of concern such as 

burrowing owl and mountain plover (Reading et al. 

1989, Tyler 1968, Clark et al 1982, Agnew 1986). 

Prairie dog colonies larger than 80 acres are protected 

from surface occupancy only if black-footed ferrets are 

found and this protection applies on BLM administered

surface only.

Smaller colonies and larger colonies without ferrets 

would effectively receive no special protection on any 

lands. Considering the ferrets extreme rarity, it is 

unlikely that any prairie dog towns would be protected 

from impacts from CBNG development. However, due 

to the anticipated release of black-footed ferrets onto 

the Northern Cheyenne Reservation in 2008, the level 

of protection could increase. Road, well pad, pipeline

and utility line placement across prairie dog towns 

would result in direct mortality and impact large 

numbers of species through habitat loss and 

displacement to unsuitable habitat, which would result 

in the loss of displaced individuals. 

As discussed in the Hydrological Resources section, 

surface water bodies would not be impacted directly 

from groundwater withdrawal due to the depth and 

confined nature of the individual coal seams. In the 

unlikely event there is a localized connection between 

a spring-fed stream and groundwater withdrawals, 

effects on wildlife and habitat would include reducing 

or even drying of springs and reduced flow and 

duration in intermittent and small perennial drainages. 

Reduced surface water would result in more xeric 

vegetation and would impact all types of wildlife, but 

would be especially important for amphibians and 

certain bird species that depend on mesic plant 

communities. Sage-grouse could suffer substantial 

impacts because broods spend much of July and 

August in more mesic sites as sagebrush habitats 

desiccate (Gill 1965, Savage 1969, Connelly and 

Markham 1983, Fischer et al. 1998). Reduced 

availability of mesic sites would reduce sage-grouse

brood survival and unfavorably affect populations 

(Connelly et al. 2000).

There would be no differences between the direct and 

indirect impacts on BLM and state lands. Impacts on 

private lands could be much more substantial because 

stipulations and mitigation measures would not apply.

Federally Listed Species

Direct impacts to federally protected species are 

prohibited by law and would be the same as under 

Alternative A. 

The potential for indirect impact would be greater 

under this alternative because of the much larger 

amount of habitat that would be disturbed or lost with 

the increased level of vegetation disturbance associated 

with the greater number of well pads, roads and utility 

lines. Increased roadways for more wells would result 

in greater human access, with the potential for more 

illegal harvest, indirect disturbance, or harassing of 

protected species. As many as 4.7 million acres of 

habitat for species sensitive to human disturbance may 

be indirectly affected by CBNG development 

(Table 4-69). Since federally listed species are often 

rare because of their sensitivity to human disturbance, 

it is unlikely that all potential indirect impacts would 

be avoided.

The same agency-applied mitigation measures

described for Alternative A would apply to 

Alternative B. The effect of these mitigation measures 

on impacts would also be the same as under 

Alternative A. 

Crow Reservation

Indirect impacts on the Crow Reservation would be 

similar to those described in general for Alternative B 

and be the result of developments in close proximity to 

reservation boundaries. 

Within the boundaries of the reservation, regulations 

related to wildlife would be under the jurisdiction of 
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tribal Laws and not state or federal laws. Full-scale 

development forecast under this alternative would 

increase the risk of impacts to wildlife on the 

reservation. 

Wildlife vulnerability to impacts would be similar to 

that presented in Table 4-69. Indirect impacts of this 

level of CBNG development on the Crow reservations 

on species sensitive to human disturbance are shown in 

Table 4-69 under cumulative impacts. 

Northern Cheyenne Reservation

There would be no direct impacts to wildlife on the 

Northern Cheyenne Reservation from off-reservation 

development. Indirect impacts on the Northern 

Cheyenne Reservation would be similar to those 

described in general for Alternative B and be the result 

of developments near reservation boundaries.

Conclusions

The same types of impacts described for wildlife and 

species of concern under Alternative A would be 

expected. However, the extent of impacts would be 

about 20 times greater in area and scope because of 

greater CBNG well development and associated direct 

and indirect impacts. Stipulations would avoid some 

impacts for certain species. However, they would not 

be 100 percent effective because some stipulations do 

not apply to operations and non-CBNG human 

activities that would be facilitated by new CBNG 

roads. The potential for impacts is high under 

Alternative B because of the large number of CBNG 

wells.

Cumulative Impacts

Cumulative impacts would be similar to those 

described for Alternative A except that the impacts 

from Montana CBNG development would be 

substantially greater. Additionally if CBNG 

development were to occur on the Crow and Northern 

Cheyenne Reservations and in the Custer National 

Forest the development is expected to result in the 

direct short-term loss of an additional 25,000 acres and 

long term loss of about 14,750 acres. Degraded habitat 

value of reclaimed lands would be similar to that 

described for Alternative A. Other actions considered 

to be cumulative impacts would result in the long term 

loss of an additional 41,000 acres.

Table 4-69 estimates additional cumulative indirect 

impacts of more CBNG development on species 

sensitive to human activities and development. It is 

estimated cumulative indirect impacts of CBNG 

development in Montana could affect sensitive wildlife 

on between 1.28 and 6.87 million acres. Since sensitive 

and federally listed species are often rare because of 

their sensitivity to human disturbance, it is unlikely 

that all potential indirect impacts would be avoided.

Alternative C—Emphasize CBNG 

Development

The same types of impacts on wildlife described for 

Alternatives A and B would occur under Alternative C. 

However, Alternative C would have direct impacts on 

more acres of wildlife habitat than Alternative B 

because Alternative C includes fewer measures to 

reduce impacts. Table 4-66 in the Vegetation section 

notes the number of acres of direct impact (habitat 

loss) and the number of miles of roads and pipeline 

and utility corridors that would result from CBNG 

development under Alternative C. Development under 

Alternative C would result in the direct short term loss 

of about 70,000 acres of wildlife habitat to well pads, 

roads (9,018 miles versus 6,680 miles for 

Alternative B) and pipeline and utility corridors 

(27,917 miles versus 20,679 miles for Alternative B). 

More land would be directly impacted because roads 

would not be required to follow existing corridors and 

there would be no requirement to place pipelines and 

utilities in corridors. Long term habitat loss would 

affect about 47,600 acres and reclaimed areas would 

have reduced habitat value. Direct and indirect impacts 

on wildlife from this scale of development would be 

widespread.

Table 4-69 estimates the area on which sensitive 

species of wildlife would be disturbed by CBNG 

development under Alternative C. Indirect disturbance 

and effective habitat loss for sensitive species would 

be the same as under Alternative B and would 

indirectly affect sensitive wildlife on between 880,000 

and 4.7 million acres. Effects of disturbance were 

described under Alternative A.

CBNG development produces excess surface water 

that has not been available in the past. It is unlikely 

that this water would go unused. Information in the 

Water Resources Technical Report (ALL 2001b) 

indicates that virtually all of the water produced during 

CBNG extraction would be suitable for livestock or 

wildlife use. Cattle typically move up to 0.6 mile from 

water to graze in steep terrain, but will move up to two

miles in relatively flat areas (Stoddart et al. 1975). 

CBNG development areas that are greater than 0.6 to 

two miles from natural or currently developed 

perennial water sources, depending on terrain, are 

either not used or used lightly by livestock on a 

seasonal basis. Increased stock water availability from 

CBNG-produced water would permit private land 

owners and state and BLM grazing permittees to adjust 

the distribution and management of their herds to use 
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more of the forage within 0.6 to two miles of CBNG 

wells. Each CBNG production well field that is located 

in an area without current perennial water sources 

could make up to several thousand acres available to 

more intensive cattle grazing. Utilization would be 

most intensive in the immediate vicinity of the water 

discharge location wells. Increased livestock grazing 

reduces forage otherwise available for wildlife and 

degrades habitat value for many species of wildlife 

(Saab et al. 1995). The additional CBNG water would 

also be available for wildlife use.

The release of untreated CBNG water to surface 

drainages and streams could result in serious erosion, 

damaging or destroying instream and stream bank 

riparian vegetation that constitutes valuable wildlife 

habitat (Regele and Stark 2000). The erosion can result 

in increased sediment loads, which along with the 

potential high salinity and sodicity, can degrade the 

stream and impact riparian vegetation. Impacts of 

discharging sodic CBNG waters would likely be 

greatest in intermittent and smaller perennial drainages 

during low-flow periods. Releases during low-flow 

periods of late summer and fall would have the greatest 

potential to impact riparian habitat and sensitive 

wildlife species such as amphibians. This is also the 

time when this vegetation is naturally stressed because 

of low water and amphibians are confined to remaining 

water or are burrowed into shallow mud. The potential 

for impacts on riparian habitat and amphibians exists 

along drainages and streams throughout the CBNG 

development area.

Because of the typically low flows of the CBNG wells 

(approximately 5 to 10 gallons per minute), it is likely 

that these impacts would be localized in the vicinity of 

the discharge, unless flow were collected from a large 

number of wells, which may occur. There are no 

apparent differences between the direct and indirect 

impacts on BLM-administered and state lands. Impacts 

on private lands would be much more substantial 

because stipulations and mitigation measures would 

not apply.

Species of Concern

Direct impacts to federally protected species are 

prohibited by law and are the same as under 

Alternatives A and B.

The potential for indirect impacts or modification to 

habitat would be greater under this alternative than for 

Alternative B (Table 4-69) because fewer potential 

impacts would be avoided. Reclamation of disturbed 

areas would not necessarily restore sites to previous 

habitat configurations or specific habitat needs of listed 

species. This alternative would have the greatest 

acreage of disturbance from roadways, pipelines and

utilities of any alternative. Power line strike hazards 

are highest with this alternative. This alternative may 

affect SAR levels in rivers that would affect BLM and 

state species of concern and bald eagle foraging, 

interior least tern foraging success and nesting habitat. 

Production water disposal could also develop riparian 

areas that would be lost after abandonment. If listed 

species come to rely on these areas of developed 

habitat, this would lead to future declines when the 

water source for them no longer exists.

Crow Reservation

Impacts to the Crow Reservation would be similar to 

the indirect impacts described in general for 

Alternative C. These indirect impacts would occur in 

areas adjacent to off-reservation CBNG developments.

Northern Cheyenne Reservation

Since there is no tribally sponsored CBNG 

development, impacts to the Northern Cheyenne 

Reservation would be similar to the indirect impacts 

described in general for Alternative C. These indirect 

impacts would occur in areas adjacent to offreservation CBNG developments. 

Conclusions

The same types of impacts described for Alternatives 

A and B for wildlife and the same as described for 

Alternative B for sensitive species would be expected. 

However, impacts would be at a greater level due to 

the emphasis on CBNG production under 

Alternative C. Approximately 21,000 more acres 

would be directly impacted in both the short and long 

term compared to Alternative B.

Cumulative Impacts

The types of cumulative impacts would be the same as 

described for Alternatives A and B. CBNG 

development is expected to result in the direct short 

and long term loss of an additional 21,000 acres 

compared to Alternative B. Degraded habitat value of 

reclaimed lands would be similar to that described for 

Alternative A. Other actions considered to be 

cumulative impacts would result in the long term loss 

of an additional 41,000 acres.

Table 4-69 estimates additional cumulative indirect 

impacts of more CBNG development on species 

sensitive to human activities and development. It is 

estimated cumulative indirect impacts of CBNG 

development in Montana could affect sensitive wildlife 

on between 1.28 and 6.87 million acres. Since sensitive 

and federally listed species are often rare because of 
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their sensitivity to human disturbance, it is unlikely 

that all potential indirect impacts would be avoided.

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

The same types of direct and indirect impacts on 

wildlife described for the Alternatives A and B and in 

Tables 4-68 and 4-69 would occur under 

Alternative D. Areas affected by direct and indirect 

impacts would be similar to those reported for 

Alternative B with the additions noted below. The 

impacts of the beneficial use of water for livestock 

grazing described for Alternative C would also occur 

under Alternative D. Unlike Alternative C, CBNG 

water discharged under Alternative D would be treated 

before release. Additional treated water provided to 

intermittent and small perennial streams may result in 

both impacts and benefits, depending mostly on the 

volume of discharge water relative to the natural flow, 

the steepness of the terrain and the erodibility of the 

soil. Relatively high volumes of water discharged into 

smaller drainages could erode the channel, destroying 

riparian vegetation either directly or as a result of 

channel down-cutting, which would reduce water 

availability to plants. Intermittent water sources that 

become perennial because of CBNG discharge would 

attract grazing livestock for longer periods of the year, 

resulting in reduced forage and cover for wildlife. 

Increased flows may also result in improved and more 

extensive riparian vegetation in intermittent drainages 

where seasonal water stress limits the current extent or 

condition of the vegetation and in more widespread 

water availability for wildlife. However, this benefit 

would be offset if more livestock grazing occurs in the 

vicinity and downstream of the discharge points. Lack 

of a requirement to reclaim roads and abandoned 

reservoirs would increase the potential for noxious 

weed occurrence and resulting habitat degradation.

There are no apparent differences between the types of 

direct impacts on BLM or state lands. Furthermore 

indirect impacts would have very little difference 

between BLM and state managed lands. Impacts on 

private lands would be much more substantial because 

stipulations and mitigation measures would not apply. 

The same agency-applied mitigation measures

described for Alternative B would apply to 

Alternative D. The effect of these mitigation measures 

on impacts would also be the same as under 

Alternative B. 

Species of Concern

Direct impacts to federally protected species are 

prohibited by law and are the same as under 

Alternative A. The potential for indirect impacts or 

modification to habitat would be greater under this 

alternative than Alternatives A or B, but less than 

Alternative C. As with those alternatives, reclamation 

of disturbed areas would not necessarily restore sites to 

previous habitat configurations or specific habitat 

needs of listed species. There would be increased 

roadways with this alternative over either 

Alternatives A or B. As with Alternative C, production 

water disposal, which would be treated under this 

alternative, could develop riparian areas that would be 

lost following abandonment. 

Mitigation is the same as for Alternative B. 

Crow Reservation

Indirect impacts on the Crow Reservation would be 

similar to those described in general for Alternative B. 

However, since there would be no tribal sponsored 

development, impacts would be limited to adjacent 

boundaries from off-reservation development. Small 

areas of private development on the reservation would 

cause direct impacts similar to those described in 

Alternative D, but adjusted for the limited scale of 

development.

Northern Cheyenne Reservation

Indirect impacts on the Northern Cheyenne 

Reservation would be similar to those described in 

general for Alternative B and are expected to occur in 

areas adjacent to off-reservation development. No 

tribal sponsored CBNG development is anticipated for 

this alternative and therefore no direct impacts to 

wildlife are expected to occur on the Reservation. 

Conclusions

Direct, indirect and residual impacts on wildlife would 

be similar to those described for Alternative B.

Under all alternatives, the variety of life forms and the 

large number of species of concern, the lack of 

specificity of project locations and the wide variation 

in habitat used by these species preclude the ability to 

identify specific impacts to each individual species of 

concern. Exploration and development of CBNG wells 

would result in a variety of direct and indirect impacts 

to species of concern. Specific impacts would depend 

on the species, the amount and type of habitat removed

and the nature and period of disturbance. Leasing 

stipulations as discussed above would reduce or avoid 

some impacts to federally listed and other sensitive 

species. However, there are no stipulations for most 

species of concern.
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Cumulative Impacts

Cumulative impacts would be similar to those 

described for Alternative B.

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

The types of impacts on wildlife under Alternative E 

would be similar to those described in Alternative A. 

However, the magnitude of the impacts would be 

substantially higher because the level of development 

would be much higher, as shown on Table 4-69. 

Examples of types of impacts similar to Alternative A 

follow: 

• Direct habitat loss and direct and indirect impacts 

because of habitat disruption and wildlife 

disturbance caused by roads, pipelines and utility 

corridors would cause the bulk of the impacts on 

wildlife.

• Direct impacts would include loss of habitat to 

accommodate project features. They would persist 

for the duration of CBNG activities and, in the 

case of loss of habitat value, beyond that time. 

Some degree of habitat loss and degradation 

would continue following CBNG abandonment 

because of ecological differences between 

reclaimed sites and native vegetation. 

• Based on the average area expected to be 

disturbed by exploration and development of each 

CBNG well, Alternative E would result in the 

direct disturbance of 73,860 acres resulting from 

development of 18,300 wells, 9,018 miles of roads

and 27,917 miles of utility corridors (Table 4-66). 

Direct impacts on wildlife would also include

mortality as relatively less mobile small mammals, 

reptiles and amphibians are killed during road and 

other site construction. Smaller mammals, reptiles

and amphibians are most likely to be directly 

killed by vehicles and are vulnerable when 

crossing roadways (USDI and USDA 2001).

• Additional direct impacts would occur on private 

lands because state and federal lease stipulations 

are recommended but not required.

• Table 4-68 indicates the relative level of 

vulnerability of different representative types of 

wildlife to direct and indirect impacts. Most 

indirect impacts on wildlife would occur during all 

CBNG phases on BLM, state and private lands. 

The duration of effects would correspond with the 

duration of each phase and the intensity of activity 

during that phase. The relative magnitude of 

impacts would be directly related to the nature and 

extent of activities associated with each phase of 

CBNG development. Some indirect effects would 

persist beyond abandonment because continued 

human use of some CBNG and user-created roads 

that are not closed and reclaimed (USDI and 

USDA 2001).

• Table 4-68 provides estimates of the area of 

habitat within which species sensitive to 

disturbance and roads may be affected both within 

and around the perimeter of CBNG well fields. 

Potentially affected areas are estimated for both 

1/2-mile and 2-mile perimeters around well fields 

and related activity (Fyfe and Olendorff 1976, 

Lyon 1983, Connelly et al. 2000). The information 

presented in Table 4-69 represents the maximum 

area of disturbance for sensitive wildlife species in 

year 20 when all wells would be developed and 

none would have been closed. By year 20, indirect 

impacts of CBNG development would affect 

sensitive species of wildlife on between 880,000 

and 4.7 million acres. Species sensitive to indirect 

impacts at this scale were discussed under 

Alternative A.

• Overhead power lines constructed for production 

wells pose problems for a variety of wildlife 

species. Raptors, sage-grouse and other species of 

birds occasionally collide with power lines, 

especially during periods of relatively poor 

visibility. Overhead power lines can benefit some 

raptors in open country by providing hunting 

perches. However, the additional perches also 

result in local population declines in prey species. 

For example, overhead power lines constructed in 

the vicinity of sage-grouse and sharp-tailed grouse 

leks and wintering areas can substantially increase 

predation rates on the grouse. The risk of raptor 

electrocution on federal and state lands is small 

because the BLM and State require power lines 

and poles be constructed to standards that would 

avoid raptor electrocution (APLIC 2006). Raptor 

and sage-grouse collisions with power lines have 

also been noted throughout the west including 

eastern Montana. 

• Stipulations prohibit surface occupancy in riparian 

areas and on floodplains of major rivers. However, 

they do not prohibit crossing of streams or 

construction of roads through riparian areas. 

Roads constructed through riparian areas and other 

forest and shrub stands for CBNG development 

and operation create edge effects and alter the 

physical environment (Trombulak and Frissell 

2000). Roads create drier conditions in the vicinity 

of the road, thereby altering habitat for many 

species. In grassland and shrubland habitats, trails 
CHAPTER 4

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and roads create edge habitat for predators and 

reduce patch size of remaining habitat for areasensitive species (USDI and USDA 2001, 

Ingelfinger 2001). Swihart and Slade (1984) found 

that prairie voles (Microtus ochrogaster), which 

occur in the Planning Area, were reluctant to cross 

tire tracks running through an open field. 

Reluctance to cross narrow gravel roads has also 

been observed in white-footed mice (Peromyscus 

leucopus), which also occur in the Planning Area

and many other rodent species (Mader 1984, 

Merriam et al. 1989, Oxley et al. 1974). 

Consequently, roads can function as barriers to 

population dispersal and movement for small 

mammals that occur in the Planning Area. 

• The assumption is made that existing stipulations 

would provide some protection to sage-grouse

habitat including lek areas, nesting habitat and 

winter range. It is recognized that these actions 

would not completely protect this species.

Mitigation measures within the WMPP will 

provide additional protective measures. Lease 

stipulations and terms and conditions would 

provide protection to raptors and the mountain 

plover. Implementation of protective measures 

contained in the WMPP would help reduce, but 

cannot avoid all, impacts to all species of wildlife 

including sagebrush-obligate birds.

See Alternative A for a complete discussion of the 

types of impacts on wildlife expected from CBNG 

development, including impacts on threatened and 

endangered and candidate species. 

Alternative E has the potential to have a greater 

magnitude of impacts than Alternatives B and D, due 

to the larger area directly disturbed and the higher 

mileage of road, pipeline and utility corridors 

constructed. However, implementation of BLM 

required Conditions of Approval and the WMPP would 

help to reduce wildlife impacts. 

Project Plans would be developed and approved using 

the programmatic guidance outlined in the WMPP. 

They would include baseline inventory for sensitive 

wildlife and habitats in areas where such inventories 

have not been completed. Certain broad landscape 

level inventories would be conducted by the BLM. The 

BLM or Operators would conduct additional, more 

detailed inventories and monitoring. Operators would 

be required to submit plans that demonstrate how their 

project design minimizes or mitigates impacts to 

surface resources and meets objectives for wildlife 

before exploration and approval of the APD. The 

WMPP would be a cooperative approach that 

incorporates adaptive management principles to try to 

deal with impacts as they occur. The WMPP also 

establishes a framework that encourages industry, 

landowners and agencies to work together 

constructively to incorporate conservation measures 

into CBNG development. All CBNG development 

would follow the programmatic guidance to address 

wildlife concerns and each individual Project Plan 

would include a site-specific Monitoring and 

Protection Plan which includes mitigation specific to 

species or local habitats. Over the life of the CBNG

project, monitoring and evaluation through area 

specific WMPPs would offer some insight as to the 

effectiveness and failures of management actions and

therefore encourage adaptive strategies to address 

specific and unforeseen problems.

Some examples of how the WMPP would be applied 

are described below. It must be recognized however, 

that because of the scale of CBNG development 

proposed under this alternative, it would only be 

possible to reduce or lessen impacts to important 

wildlife habitats utilizing measures described in the 

WMPP.

As discussed in alternative A, the primary objective of 

reclamation is to restore vegetative cover to the 

disturbed site. With the required seed mixes, 

restoration to near-native conditions is not likely to 

occur. However, flexibility provided by the WMPP 

allows for more creative options in reclamation plans 

to restore important wildlife habitats. An example 

would be to focus on restoration of sagebrush stands 

on big game winter ranges as opposed to establishing 

herbaceous cover only. 

As part of the approval process for project protection 

plans, location and use of roads would be a very high 

focus. Project design would include locating roads in 

such a manner as to avoid crucial big game and sagegrouse winter ranges (i.e. south facing slopes, 

sagebrush flats and valley floors), raptor nesting areas 

and prairie dog towns. Additionally, stipulations may 

be applied that preclude use of these roads during 

critical time periods of the year (seasonal restrictions) 

or day (timing restrictions) that would apply to all 

CBNG activities.

The power infrastructure associated with CBNG 

development is identified as a major wildlife impact. 

Agencies already require all powerlines to be raptor 

proof according to accepted standards. However, 

additional stipulations may be required based on site 

specific needs. Examples of this may be locating 

powerlines away from sage-grouse leks and winter 

concentration areas, burying powerlines in crucial

areas and applying more aggressive raptor-proofing 

options than previously required. 

Mandatory mitigation measures are listed in Chapter 2.
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Species of Concern

The types of direct and indirect impacts would be 

similar to the other development alternatives. 

Alternative E has the potential to have a greater 

magnitude of impacts to species of concern than 

Alternatives B and D, due to the larger area that would 

be directly disturbed and the higher mileage of road, 

pipeline and utility corridors to be constructed. 

However, implementation of BLM required COAs and 

the WMPP would help to reduce impacts to species of 

concern. 

The WMPP addresses guidance for developing Plans 

of Development. Project Plans and conservation 

measures applied as Conditions of Approval provide a 

full range of practicable means to avoid or minimize 

harm to wildlife species or their habitats. Operators 

would minimize impacts on wildlife by incorporating 

applicable WMPP programmatic guidance into Project 

Plans. Not all measures may apply to each site-specific 

development area and means to reduce harm are not 

limited to those identified in the WMPP. BLM and 

MFWP would work together to collect baseline 

information about wildlife and sensitive habitats 

possibly containing special status species.

The WMPP is intended to reduce potential impacts on 

a variety of sensitive species by requiring inventories 

prior to exploration. This action would likely reduce 

potential direct impacts on sensitive species and may 

also reduce potential indirect impacts in some cases. 

However, given the scale of CBNG development, it is 

very unlikely that all direct and indirect impacts on 

species of concern can be avoided. Monitoring 

findings may result in additional conditions of 

approval and mitigation measures for CBNG 

development that occurs after initial monitoring data 

are collected and analyzed, which could further reduce, 

but not eliminate, potential impacts on sensitive 

species.

Alternative E does include indirect potential West Nile 

virus impacts to sage-grouse that would not occur 

under Alternatives B, C and D. Specifically, 

Alternative E would include approximately 8,285 

infiltration and evaporation ponds, each assumed to be 

about 5 acres in size that could serve as sources for the 

mosquito (Culex tarsalis) responsible for the spread of 

the West Nile virus. An on-going study by researchers 

at Montana State University has indicated this

mosquito thrives in CBNG holding ponds in northern 

Wyoming (Montana State University News Service 

2005). Measures to minimize the exploitation of the 

CBNG ponds by breeding mosquitoes are included in 

the WMPP and would be implemented under 

Alternative E.

Crow Reservation

Indirect impacts on the Crow Reservation would be 

similar to those described in general for Alternative E. 

Impacts would be limited to adjacent boundaries from 

off-reservation development. 

Northern Cheyenne Reservation

Indirect impacts on the Northern Cheyenne 

Reservation would be similar to those described in 

general for Alternative E. Specific mitigation measures

proposed by the Northern Cheyenne Tribe that would 

be implemented by the BLM are described in the 

Northern Cheyenne Mitigation Appendix. 

Conclusions

The types of direct, indirect, residual and cumulative 

impacts would be generally the same as those noted for 

Alternatives A and B. Discharge of treated water to 

intermittent and small perennial streams would result 

in both impacts and benefits to aquatic/riparian 

vegetation, amphibians, aquatic wildlife and 

invertebrates; depending mostly on the volume and 

quality of discharge water relative to the natural flow. 

Impacts to wildlife from habitat loss, wildlife 

disturbance and mortality, including illegal harvest, 

have the potential to be greater under this alternative 

than either Alternatives B or D (Table 4-66). However, 

as mentioned earlier, implementation of the WMPP 

would reduce direct and indirect effects to wildlife.

All wildlife species would be impacted at some level 

by habitat changes caused by the replacement of predisturbance vegetation with lesser diversity of 

vegetation following reclamation, increased access

through increased roads and other indirect effects. 

However, implementation of stipulations, the WMPP

and adaptive management should ensure species do not 

decline to the point they need protection of the ESA. 

Recent research (Holloran and Anderson 2004, 

Holloran 2005); and ongoing studies specific to CBNG 

development in the Powder River Basin indicate 

potential for declining local populations of sage-grouse 

under this alternative. For federally-listed species, 

some effects may occur, but effects are not likely to 

cause adverse population responses.

The magnitude of cumulative impacts would be similar 

to those described for Alternative C.

Alternative F—Phased Development 

Multiple Screens (High Range)

Under this alternative, the type of impacts to wildlife 

would be similar as the other development alternatives. 

However, the magnitude of direct impacts is expected 

to be less than the other action alternatives for the 
CHAPTER 4

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following reasons: (1) as with Alternatives B and D, 

Alternative F provides restrictions on the amount of 

surface disturbance on federal leases within crucial 

habitat areas; (2) Alternative F (as with Alternative E) 

includes additional conservation measures described in 

the WMPP; (3) Alternative F includes thresholds on 

impacts to crucial habitats, which would reduce 

impacts to sagebrush and grassland obligated species;

(4) Alternative F includes sage-grouse habitat 

conditions for protecting crucial habitat areas and 

avoiding the displacement of sage-grouse; and (5) 

Alternative F includes phasing of development that 

would result in a lesser magnitude of impact for a 

particular area over time.

The threshold component of Alternative F would limit 

the amount of impacted habitat on BLM-administered

surface or on private surface overlaying federal 

minerals within each 4th Order watershed. The 

threshold value would allow no more than 20 percent 

of any crucial habitat area within to be directly 

impacted over a 20-year period within the watershed. 

This would include removal of crucial habitat (e.g., 

nesting, brood-rearing and wintering habitats), 

resulting from the proposed project activities, a 400 

meter corridor along major travel routes (12 or more 

vehicles per day) and other unrelated projects that 

result in habitat removal. Best available science 

(including any information available from ongoing 

research, modeling and other sources), combined with 

documentation specific to POD-level analysis, would 

be used to document existing crucial habitat and 

impact areas. Research is currently being conducted 

within the Powder River Basin of Montana and 

Wyoming, specifically on sage-grouse and habitat use.

Implementation of this threshold would have little 

effect on protecting species or habitats, as it is unlikely 

disturbance would reach the 20 percent threshold over 

a 20-year period. In addition, seasonal restrictions do 

little to protect wildlife beyond the time period 

development takes place. Operation and maintenance 

of wells are not precluded by this stipulation, which 

often result in impacts to habitat in which the 

stipulations were intended to protect. The “adaptive 

management” feature (identified in Chapter 2 and 

expanded in the Wildlife Monitoring and Protection 

Plan in the Wildlife Appendix) would increase BLM’s

ability to modify the threshold percentage if needed, to 

reduce the magnitude and level of habitat impacts. The 

adaptive management approach would include utilizing 

and evaluating new information to form additional or 

to change conditions of approvals. Important 

information such as the on-going sagebrush/sagegrouse research in CBNG (pre and post) development 

areas in Montana and Wyoming, would be utilized. 

BLM would manage sage-grouse habit using a 

combination of the stipulations attached to the oil/gas 

leases, management identified in the 20/20 wildlife 

screen and stipulations identified in the WMPP. This 

alternative, while developed using the best information 

available at the time, would likely result in a 

significant loss of sag-grouse habitat in the areas of 

and directly development.

For indirect impacts, new information (relative to the 

Statewide Document) is presented in Table 4-70. The 

table provides information by watershed, as 

Alternative F includes maximum thresholds for 

impacts based on the watershed scale. For the entire 

Planning Area, total acres of indirect impacts are 

different between Table 4-69 and Table 4-68 because 

Table 4-69 is based on slightly different assumptions 

regarding well development. Specifically, the indirect 

impacts (calculated in Table 4-69) assume all wells 

will be developed at the same density (8, 16, or 24 

wells per square mile) while Table 4-70 incorporates 

recent experience indicating that well site density can 

vary depending on the available coal layers. Well site 

density is a more accurate measurement because 

existing well sites may have as many as five wells.

Taken together, Tables 4-69 and 4-70 provide a range 

of expected indirect impacts from the development 

alternatives. Note that in all cases, the tables indicate 

total acres of indirect impacts are the same under all 

action alternatives. In reality, acreages of indirect 

impacts from Alternative F are expected to be less, 

given the habitat and development thresholds that are 

part of this alternative. In addition, note that indirect 

effects from new utility lines, pipelines and roads 

would not be the same under each alternative. 

Specifically, Alternatives B, D and F would have 

fewer indirect impacts from utility lines, pipelines and

roads, since these alternatives include more restrictions 

on their development than the other action alternatives. 

Types of indirect effects on wildlife from roads, 

pipelines and utility lines are described above in the 

discussion of Alternative A.

Species of Concern

For the same reasons as described above, Alternative F 

would include the same types of direct and indirect 

impacts to species of concern as described in the other 

development alternatives (B, C, D and E) but at a 

lesser magnitude. Under Alternative F, thresholds for 

impacts to crucial habitat would provide unique 

protection compared to the other development 

alternatives. Fragmentation of habitat, dispersal, 

colonization and extinction patterns would be reduced 

under this alternative. In addition, Alternative E 

discussed potential indirect effects to sage-grouse from 

holding ponds and risk of West Nile virus infection. 
Wildlife

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TABLE 4-70 

AREA OF POTENTIAL INDIRECT WILDLIFE DISTURBANCE AND DISPLACEMENT WITHIN AND AROUND STANDARD-SIZED1

CBNG WELL FIELDS FOR MORE SENSITIVE WILDLIFE SPECIES BY 4TH ORDER WATERSHED, ALTERNATIVES B, C, D, E, F AND H

Acres in 

Montana

Number of 

Production 

Wells per 

Watershed 

(Assuming 10% 

are Dry Holes)

Well Fields per Watershed2 Additional 

Acreage of 

Indirect 

Disturbance 

within 1/2 mile 

of Well Field 

Perimeters3,4

Total 

Indirect 

Disturbance1 

within Well 

Fields

Total 

Indirect 

Disturbance 

from CBNG 

Development4

Percentage of 

Watershed in 

Montana

Indirectly 

Watershed Disturbed

200 Wells 

per Field, 8 

Wells per 

Square Mile

400 Wells 

per Field, 16 

Wells per 

Square Mile

600 Wells 

per Field, 24 

Wells per 

Square Mile

Total 

Number of 

Standard 

Sized Well 

Fields

Clark's Fork Yellowstone 978,374 405 2.0 0.0 0.0 2.0 14,256 32,400 46,656 4.77%

Little Bighorn 830,773 608 3.0 0.0 0.0 3.0 21,402 48,640 70,042 8.43%

Little Powder 416,598 180 0.9 0.0 0.0 0.9 6,336 14,400 20,736 4.98%

Lower Bighorn 1,266,927 720 3.6 0.0 0.0 3.6 25,344 57,600 82,944 6.55%

Lower Tongue 1,835,479 3,105 7.8 3.9 0.0 11.6 81,972 186,300 268,272 14.62%

Lower Yellowstone-Sunday 3,062,384 1,530 7.7 0.0 0.0 7.7 53,856 122,400 176,256 5.76%

Middle Musselshell 1,223,591 90 0.5 0.0 0.0 0.5 3,168 7,200 10,368 0.85%

Middle Powder 454,527 1,890 6.6 1.4 0.0 8.0 56,549 128,520 185,069 40.72%

Mizpah 510,281 113 0.6 0.0 0.0 0.6 3,978 9,040 13,018 2.55%

Rosebud 834,998 3,240 12.2 2.0 0.0 14.2 99,792 226,800 326,592 39.11%

Stillwater 521,362 90 0.5 0.0 0.0 0.5 3,168 7,200 10,368 1.99%

Upper Musselshell 2,570,399 68 0.3 0.0 0.0 0.3 2,394 5,440 7,834 0.30%

Upper Tongue 586,044 3,465 0.0 4.3 2.9 7.2 50,820 115,500 166,320 28.38%

Upper Yellowstone-Lake Basin 1,003,984 720 3.6 0.0 0.0 3.6 25,344 57,600 82,944 8.26%

Upper Yellowstone-Pompey's Pillar 1,279,948 180 0.9 0.0 0.0 0.9 6,336 14,400 20,736 1.62%

TOTAL 16,403 50.0 11.7 2.9 64.6 454,714 1,033,440 1,488,154

1 For this table, a standard-sized well field is considered to be 200 well sites with an 80-acre spacing, which results in a total standard field size of 16,000 acres. Number of wells and acres of 

disturbance for Alternative F represent the maximum development for this alternative. In reality, Alternative F may include a lesser acreage of effect, due to the threshold limits and 

implementation of the WMPP that is part of this alternative.

2 When more than one layer of coal is present, wells can be co-located on the surface within the same 80-acre spacing. The following watersheds have multiple coal layers: Lower Tongue, 

50% with 2 layers; Middle Powder, 30% with 2 layers; Rosebud, 25% with 2 layers; and Upper Tongue, 50% with 2 layers, 50% with 3 layers.

3 The additional acreage within 1/2 mile of a standard-sized well field (16,000 acres) is approximately 7,040 acres (see Table 4-68). 

4 These acreages assume there is no overlap between affected areas of adjacent well fields. Overlap would reduce the total area of indirect disturbance outside well field perimeters.
CHAPTER 4

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Note that Alternative F could include as many holding 

ponds as Alternative E only if the development 

thresholds were not met under Alternative F. 

Crow Reservation

Types of indirect impacts to wildlife on the Crow 

Reservation would be similar to those described in 

general for the development alternatives. However, the 

phased aspect of development, the threshold on 

disturbance of crucial habitats and adaptive 

management techniques would result in reduced 

indirect impacts to Crow Reservation wildlife, relative 

to Alternatives B, C, D and E. 

Northern Cheyenne Reservation

Effects to Northern Cheyenne Tribe wildlife resources 

would be similar to that described for the Crow 

Reservation. 

Conclusion

Under this alternative, cumulative impacts would be 

less than Alternative E, primarily due to the 

implementation of cumulative and watershed-specific 

numerical limits on the number of federal CBNG 

APDs approved per year.

All wildlife species would be impacted at some level 

by habitat changes caused by vegetation removal not 

reclamation to predisturbance conditions, increased 

access through increased roads and other indirect 

effects. However, implementation of stipulations, the 

WMPP, development thresholds and adaptive 

management would help ensure species do not decline 

to the point needing protection of the ESA. An 

exception to this finding is uncertainty concerning 

declines of sage-grouse populations. Recent research 

(Holloran and Anderson 2004, Holloran 2005); and 

ongoing studies specific to CBNG development in the 

Powder River Basin indicate potential for declining 

local populations of sage-grouse under this alternative. 

Most significantly is the finding related to the need to 

minimize disturbance to large tracts of remaining high 

quality sagebrush communities. For federally-listed 

species, some effects may occur, but are not likely to 

cause adverse population responses.

Alternative G—Phased Development 

Multiple Screens (Low Range)

This alternative would include the same type of 

impacts as the other development alternatives. 

However, the magnitude of direct and indirect effects 

to wildlife would be less than all other development 

alternatives (Alternatives B, C, D, E and F), due to the 

lower level of well development. As with Alternative 

F, Alternative G includes conservation measures as 

described in the WMPP that would also reduce direct 

and indirect effects to wildlife. Alternative G also 

includes the same thresholds levels for impacts as 

Alternative F. However, given the relatively low level 

of development under Alternative G, these thresholds 

may never be met under this Alternative. Alternative G 

would directly affect 19,665 acres, compared to 55,210 

acres to 73,860 acres that would be directly affected 

under Alternatives B through F (Table 4-66). Total 

acres of habitat indirectly disturbed under Alternative 

G would be approximately one-third that of the other 

development alternatives (Tables 4-70 and 4-71).

As with Alternatives B, D and F, Alternative G would 

have fewer indirect impacts from utility lines and 

pipelines than Alternatives C and E. Alternative G 

includes fewer CNBG road miles than any other 

development alternative and consequently, direct and 

indirect effects to wildlife from roads would be less 

under this alternative.

Species of Concern

Given the lower level of well development and roads 

and the inclusion of the WMPP conservation measures 

under Alternative G, this alternative would have less 

direct and indirect effect on species of concern than 

Alternatives B, C, D, E, or F. However, the risk of 

West Nile virus to sage-grouse would be greater than 

Alternatives B, C and D, but less than Alternatives E 

or F. 

Crow Reservation

Types of indirect impacts to wildlife on the Crow 

Reservation would be similar to indirect effects 

described in the other development alternatives. 

However, the magnitude of indirect impacts would be 

less than all other development alternatives due 

primarily to the lower level of well development under 

Alternative G.

Northern Cheyenne Reservation

Effects on Northern Cheyenne Tribe wildlife resources 

would be the similar to those described for the Crow 

Tribe. 
4-286

WildlifeCHAPTER 4

TABLE 4-71 

AREA OF POTENTIAL INDIRECT WILDLIFE DISTURBANCE AND DISPLACEMENT WITHIN AND AROUND STANDARD-SIZED1

CBNG WELL FIELDS FOR MORE SENSITIVE WILDLIFE SPECIES BY 4TH ORDER WATERSHED UNDER ALTERNATIVE G

Acres in 

Montana

Number of 

Production 

Wells per 

Watershed 

(Assuming 10% 

are Dry Holes)

Well Fields per Watershed2 Additional 

Acreage of 

Indirect 

Disturbance 

within 1/2 mile 

of Well Field 

Perimeters3,4

Total Indirect 

Disturbance1 

within Well 

Fields

Total 

Indirect 

Disturbance 

from CBNG 

Development4

Percentage 

of 

Watershed

in Montana

Indirectly 

Watershed Disturbed

200 Wells 

per Field, 8 

Wells per 

Square Mile

400 Wells 

per Field, 16 

Wells per 

Square Mile

600 Wells 

per Field, 24 

Wells per 

Square Mile

Total 

Number of 

Standard 

Sized Well 

Fields

Clark's Fork Yellowstone 978,374 153 0.8 0.0 0.0 0.8 5,386 12,240 17,626 1.80%

Little Bighorn 830,773 216 1.1 0.0 0.0 1.1 7,603 17,280 24,883 3.00%

Little Powder 416,598 63 0.3 0.0 0.0 0.3 2,218 5,040 7,258 1.74%

Lower Bighorn 1,266,927 252 1.3 0.0 0.0 1.3 8,870 20,160 29,030 2.29%

Lower Tongue 1,835,479 1,089 2.7 1.4 0.0 4.1 28,750 65,340 94,090 5.13%

Lower Yellowstone-Sunday 3,062,384 540 2.7 0.0 0.0 2.7 19,008 43,200 62,208 2.03%

Middle Musselshell 1,223,591 36 0.2 0.0 0.0 0.2 1,267 2,880 4,147 0.34%

Middle Powder 454,527 666 2.3 0.5 0.0 2.8 19,927 45,288 65,215 14.35%

Mizpah 510,281 36 0.2 0.0 0.0 0.2 1,267 2,880 4,147 0.81%

Rosebud 834,998 1,143 4.3 0.7 0.0 5.0 35,204 80,010 115,214 13.80%

Stillwater 521,362 36 0.2 0.0 0.0 0.2 1,267 2,880 4,147 0.80%

Upper Musselshell 2,570,399 27 0.1 0.0 0.0 0.1 950 2,160 3,110 0.12%

Upper Tongue 586,044 1,215 0.0 1.5 1.0 2.5 17,820 40,500 58,320 9.95%

Upper Yellowstone-Lake Basin 1,003,984 270 1.4 0.0 0.0 1.4 9,504 21,600 31,104 3.10%

Upper Yellowstone-Pompey's Pillar 1,279,948 81 0.4 0.0 0.0 0.4 2,851 6,480 9,331 0.73%

TOTAL 5,823 17.9 4.1 1.0 23.0 161,893 367,938 529,831

1 For this table, a standard-sized well field is considered to be 200 well sites with an 80-acre spacing, which results in a total standard field size of 16,000 acres.

2 When more than one layer of coal is present, wells can be co-located on the surface within the same 80-acre spacing. The following watersheds have multiple coal layers: Lower Tongue, 

50% with 2 layers; Middle Powder, 30% with 2 layers; Rosebud, 25% with 2 layers; and Upper Tongue, 50% with 2 layers, 50% with 3 layers.

3 The additional acreage within 1/2 mile of a standard-sized well field (16,000 acres) is approximately 7,040 acres (see Table 4-68). 

4 These acreages assume there is no overlap between affected areas of adjacent well fields. Overlap would reduce the total area of indirect disturbance outside well field perimeters.
CHAPTER 4

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4-287

Conclusion

Under this alternative, cumulative impacts would be 

less than the other development alternatives, primarily 

due to the reduced level of well development under 

Alternative G.

All wildlife species would be impacted at some level 

by habitat changes caused by vegetation removal not 

fully recovered with reclamation to predisturbance 

conditions, increased access through increased roads

and other indirect effects. However, implementation of 

stipulations, the WMPP, development thresholds and

adaptive management would help ensure species do 

not decline to the point of needing protection under the 

ESA. For federally-listed species, some effects may 

occur, but effects are not likely to cause adverse 

population responses.

Alternative H—Preferred Alternative - 

Multiple Screens

For wildlife, restrictions on CBNG development would 

be similar to Alternative F, but would incorporate 

adaptive management to identify conditions of 

approval (COAs), BMPs and alternative development 

schemes, based on available science and monitoring 

information (see the WMPP). BLM would work with 

CBNG operators, surface owners, Native American 

tribes, FWS and MFWP to identify any additional 

protection measures necessary. On split estate lands, 

BLM recognizes that achieving the objectives of this 

alternative would require cooperation with surface 

owners.

Specifically, this alternative includes (1) changes in 

management if mule deer or pronghorn populations 

decline by more than 30 percent in a 3-year period, (2) 

management modification if monitoring data indicate a 

change in wildlife species populations within crucial 

habitats on or adjacent to POD areas where federal 

mineral ownership occurs for Tier 1 species identified 

in the Montana Comprehensive Fish and Wildlife 

Strategy (2005c), (3) sage-grouse would be managed 

to maintain populations trends consistent with adjacent 

“control” populations, (4) through the use of BMPs, 

adaptive management, etc. management changes will 

be made if populations decline by 25 percent over a 

five year period, (5) siting surface disturbance 

proposals to meet objectives for sage-grouse habitat 

management within 1 mile of a lek (6) restrictions on 

new roads and utilities (either explicitly or through 

watershed-level resource analysis; (7) burying all 

powerlines in sage-grouse habitat, where feasible and

(8) conservation measures described in the WMPP. As 

research and monitoring continued, BLM and partners 

might develop new COAs and BMPs to supplement 

those already contained in the WMPP and other BLM 

publications.

While Alternative F includes a phased development 

component that would limit the number of APDs 

approved each year, Alternative H would require POD 

development and approval be based on the four 

resource screens and watershed-level impact analysis 

so that the rate of APD approval is expected to be 

similar to that of Alternative F. 

Alternative H would allow CBNG to occur, with strict 

application of COAs and monitoring of populations to 

with a goal of managing habitat to ensure populations 

remain consistent with adjacent control populations. In 

addition, even with the application of the best science, 

BMPs etc. population may be negatively impacted. 

Monitoring will focus on these changes and if sagegrouse populations decline by 25 percent or more over 

5 years or if populations appear to be headed in this 

direction, BLM would implement changes in 

management designed to maintain sage-grouse 

populations at a level consistent with adjacent 

populations. Alternative H would start with more

restrictions and increase restrictions if monitoring 

showed BMPs were unsuccessful at meeting the 

objectives of this alternative. Recent research 

(Holloran and Anderson 2004, Holloran 2005); and 

ongoing studies specific to CBNG development in the 

Powder River Basin indicate potential for declining 

local populations of sage-grouse unless large quality 

habitat areas are maintained that provide suitable 

habitat for all critical life cycle periods (i.e., brood 

rearing, breeding and wintering). 

As noted previously, Alternative H has the following 

objectives: maintaining the connectivity of sagegrouse habitat within the PRB and adjacent regions, 

maintenance of source populations for repopulation of 

areas from which displacement may have occurred due 

to CBNG development and maintain sage-grouse 

habitat so that population trends follow the general 

magnitude of decline or increase as that occurs on the 

control leks. 

Even with the possibility of a slower pace of 

development in crucial sage-grouse habitat under this 

alternative, there is a potential that sage-grouse may be 

displaced from some of the habitat before the impacts 

become evident in the monitoring data, which would 

reduce sage-grouse populations. However, the

monitoring and adaptive management may limit the 

extent of decline and allow BLM to modify 

management to stabilize populations. 

Consequently, effects of Alternative H on wildlife 

would be similar to Alternative F, except for sagegrouse and sagebrush obligate species.
CHAPTER 4

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General Effects to Wildlife

As with the other development alternatives, CBNG 

development and construction and use of related 

facilities (i.e., roads, pipelines and utility corridors) can 

cause numerous direct and indirect effects to wildlife. 

The primary effects include: (1) direct mortality (from 

crushing by construction equipment, collision with 

vehicles and collision with powerlines); (2) habitat 

loss, degradation (e.g., invasion of noxious weeds, 

changes in water quantity and quality) and

fragmentation; (3) noise and visual disturbance; (4) 

increased legal and illegal hunting; and (5) barriers to 

dispersal and movement. Effects to individual species 

depend on extent, location and timing of the activity 

and sensitivity of the species, among other factors. 

Table 4-68 indicates the relative level of vulnerability 

of different representative types of wildlife to direct 

and indirect impacts. 

As under Alternative F, the threshold component of 

Alternative H would limit the amount of impacted 

habitat on BLM-administered surface or on private 

surface overlaying federal minerals. BLM would 

manage disturbance in crucial habitats (e.g., crucial 

brood rearing/breeding/wintering habitat) where 

federal mineral ownership occurred. Crucial habitat for 

additional species, particularly Tier 1 species identified 

in the Montana Comprehensive Fish and Wildlife 

Strategy (MFWP 2005d), might be identified and 

existing crucial habitats modified based on additional 

habitat monitoring/surveys. 

A requirement for each proposed POD would be to 

identify crucial habitat polygons during project 

implementation. Management might be modified if 

monitoring data indicated a change in wildlife species 

populations within crucial habitats on or adjacent to 

POD areas. The “adaptive management” feature 

(identified in Chapter 2 and expanded in the Wildlife 

Monitoring and Protection Plan in the Wildlife 

Appendix) would increase the BLM’s ability to modify 

the threshold percentage, if needed, to reduce the 

magnitude and level of habitat impacts. 

Tables 4-66, 4-68 and 4-70 provide quantitative 

information on acres of direct and indirect impacts 

under the development alternatives. Assuming full 

CBNG development, Alternative H would result in the 

direct disturbance of up to 59,045 acres, resulting from 

development of 18,225 wells, 6,662 miles of roads and

20,623 miles of pipeline and utility corridors (Table 4-

66). Taken together, Tables 4-70 and 4-71 provide a 

range of expected indirect impacts from the 

development alternatives. In all cases, the tables 

indicate that the total acres of indirect impacts are the 

same under all action alternatives. In reality, acreages 

of indirect impacts from Alternative H are expected to 

be less, given the habitat and development thresholds 

that are part of this alternative. In addition, note that 

indirect effects from new utility lines, pipelines and

roads would not be the same under each alternative. 

Specifically, Alternatives B, D, F and H would have 

fewer indirect impacts from utility lines, pipelines and

roads, since these alternatives include more restrictions 

on their development than the other action alternatives. 

Lower-intensity development, or no development, 

within the crucial sage-grouse habitat areas would 

further reduce the overall impacts to other species that 

occupy these habitat areas. 

As with Alternatives E, F and G, PODs under 

Alternative H would be developed and approved using 

the programmatic guidance outlined in the WMPP, 

BMPs, adaptive management and the stipulations 

identified in this document. These PODs would 

include baseline inventories for sensitive wildlife and 

habitats in areas where such inventories have not been 

completed as well as certain broad landscape-level 

inventories. Operators would be required to submit 

plans demonstrating how their project design 

minimizes or mitigates impacts to surface resources 

and meets objectives for wildlife before exploration 

and approval of the APD. The WMPP would be a 

cooperative approach incorporating adaptive 

management principles to try to address impacts as 

they occur. Over the life of the CBNG project, 

monitoring and evaluation through area-specific 

WMPPs would offer some insight as to the 

effectiveness of management actions and therefore 

encourage adaptive strategies to address specific or

unforeseen problems.

Species of Concern

The types of direct and indirect impacts would be 

similar to the other development alternatives and to 

those described in the “General Effects to Wildlife” 

section under Alternative H above. However, 

implementation of the sage-grouse population change

threshold combined with the WMPP would reduce 

impacts of CBNG development for most sensitive 

species compared to Alternatives B, C, D and E. 

Fragmentation of natural populations, including sagegrouse; and dispersal, colonization and extinction 

patterns would be reduced under this alternative. As 

with Alternative F, Alternative H could include 

approximately 8,286 infiltration and evaporation ponds 

(if not limited by development thresholds) with each 

pond assumed to cover about five acres and serving as 

a potential source for West Nile virus. Measures to 

minimize the exploitation of the CBNG ponds by 

breeding mosquitoes are included in the WMPP and 

would be implemented under Alternative H. 
CHAPTER 4

Wildlife

4-289

Crow Reservation

Indirect impacts on the Crow Reservation would be 

similar to those described in general for Alternative H. 

Impacts would be reduced from federal CBNG wells 

by implementation of mitigation and monitoring 

requirements within 5 miles of the Reservation 

boundary. 

Northern Cheyenne Reservation

Indirect impacts on the Northern Cheyenne 

Reservation would be similar to those described in 

general for the Crow Reservation 

Conclusions

The types of direct, indirect, residual and cumulative 

impacts would be generally the same as those noted for 

the other development alternatives.

Given the threshold limits on development and the 

implementation of the WMPP, impacts to wildlife 

from habitat loss, wildlife disturbance and mortality 

are expected to be less than Alternatives B through E,

and between Alternatives F and G. 

All wildlife species would be impacted at some level 

by habitat changes caused by the replacement of 

predisturbance vegetation with a different composition 

of vegetation following reclamation after well 

abandonment, increased access through increased 

roads and other indirect effects. However, 

implementation of stipulations, the WMPP, 

development thresholds, crucial sage-grouse habitat 

area objectives and adaptive management would 

ensure species do not decline to the point they need 

protection of the ESA as a result of BLM approved

actions. For federally-listed species, some effects may 

occur, but effects are not likely to be adverse. Note that 

the Biological Assessment (see the Wildlife Appendix)

provides additional information on effects to federallylisted species.
CHAPTER 4

Wildlife

4-290

Aquatic Resources

Wildlife (Aquatic Resources)

Fish species vary between watersheds within the FSEIS

Planning Area from 8 in the Little Big Horn River to 47 in the 

Yellowstone River. 

Special Status Aquatic Species: Pallid sturgeon, Blue sucker, 

Northern redbelly X Finescale dace, Paddlefish, Pearl dace, 

Sauger, sturgeon chub and Yellowstone cutthroat trout.

Alternative A

No Action (Existing CBNG Management)

• Minor short-term impacts on aquatic resources during 

CBNG exploration and production may result from 

increased sediment delivery and its effects on aquatic 

habitat and organisms, possible impedance of fish 

movements, potential for accidental spills of petroleum 

products and possibly increased fish harvest. 

• Relatively minor long-term increases in river flow and 

TDS concentration from production water discharge 

would not be expected to impact aquatic resources.

• Conditions of MPDES Permits would provide legally 

enforceable assurances that water quality, aquatic 

resources and the beneficial uses of receiving waters 

would not be degraded by production water discharges. 

• Impacts from CBNG abandonment would be minor and 

subside over time.

Alternative B

CBNG Development with Emphasis on Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

• The same types of impacts described for Alternative A 

(No Action) would occur under Alternative B, except as 

noted in the following two bullets.

− The scale of potential impacts associated with 

sediment delivery, fish movements, petroleum spills

and fish harvest would be greater under Alternative 

B because of the development of over 18,000 CBNG 

wells across a much larger geographic area.

− No CBNG production water would be discharged to 

surface drainages under Alternative B. 

• Based on fish species, fisheries management policies, 

fisheries resource values and projected intensity of CBNG 

development, the drainages most sensitive to the effects of 

CBNG development would be the Lower Bighorn, Upper 

Tongue and Little Bighorn; then the Lower Tongue, Little 

Powder and Rosebud; followed by the Mizpah. 

• The potential for affecting aquatic resources, particularly 

in sensitive drainages, would be less under Alternative B 

than under Alternatives C or D.

Alternative C

Emphasize CBNG Development

• The same types of impacts described for Alternative A 

would occur under Alternative C, but they would occur on 

a far greater scale because of the development of over 

18,000 CBNG wells.

• A total of 0.67 billion cubic feet of untreated CBNG

production water would be discharged to drainages each 

year. Resultant flow and TDS increases could potentially 

impact aquatic organisms, especially in smaller drainages 

during dry times of the year. 

• Conditions of MPDES Permits would provide legally 

enforceable assurances preventing the degradation of 

water quality, aquatic resources and the beneficial uses 

of receiving waters. 

• The potential for affecting aquatic resources in the 

sensitive drainages would be greater under Alternative C 

than under Alternatives B or D.

Alternative D

Encourage CBNG Exploration and Development While 

Maintaining Existing Land Uses

• The same types of impacts described for Alternative A 

would occur under Alternative D, but they would occur 

on a far greater scale because of the development of over 

18,000 CBNG wells. 

• The annual discharge of 2.24 billion cubic feet of treated 

CBNG production water through pipelines or 

constructed water courses and resultant flow increases 

could impact aquatic resources in smaller drainages 

during dry times of the year. 

• The treatment of CBNG production water prior to its 

discharge would greatly reduce the potential for elevated 

TDS and salinity impacts on aquatic resources. 

• MPDES Permits would provide legal assurances that 

water quality, aquatic resources and beneficial uses of 

receiving waters would be protected. 

• The potential for affecting aquatic resources in the 

sensitive drainages would be greater under Alternative D 

than under Alternative B but less than under 

Alternative C.

Alternative E

CBNG Exploration and Development with Enhanced 

Mitigation to Minimize Environmental Impacts While 

Maintaining Existing Land Uses

• The same types of impacts described for Alternative A 

would occur under Alternative E, but the impacts would 

occur on a far greater scale because of the development 

of over 18,000 CBNG wells.

• The potential for affecting aquatic resources would be 

greater under Alternative E than under Alternatives B or 

D but less than under Alternative C. 

• Pipelines or constructed water courses and resultant flow 

increases could impact aquatic resources in smaller 

drainages during dry times of the year. 

• About 2.24 billion cubic feet of CBNG production water 

managed through flexible options, but allows no 

degradation of water quality (including thermal criteria). 

• The required Water Management Plans and MPDES 

Permits would provide assurances that water quality, 

aquatic resources and beneficial uses of receiving waters 

would be protected. 

• The potential for affecting aquatic resources in sensitive 

drainages would be greater than Alternatives B and D 

but less than under Alternative C.
CHAPTER 4

Wildlife

4-291

Alternative F

Phased Development Multiple Screens (High Range)

• The same types of impacts described for Alternative A 

would occur under Alternative F, but the impacts would 

occur on a far greater scale because of the development 

of over 18,000 CBNG wells.

• The potential for affecting aquatic resources would be

more than Alternatives B and G, similar to Alternatives

D and E but less than under Alternative C.

• About 2.24 billion cubic feet of CBNG production water 

managed through flexible management options, but 

limits the volume of untreated water discharged to 

surface waters. 

• MPDES Permits would provide assurances that water 

quality, aquatic resources and beneficial uses of 

receiving waters would be protected.

• Limits CBNG development and total disturbed habitat 

annually and by watershed.

• Sequential and controlled development schedule, 

combined with watershed-level analysis, provides a 

framework for assessing potential impacts through a 

systematic monitoring program.

• Incorporates Adaptive Management approach in the 

phased development process that uses the monitoring 

data.

Alternative G

Phased Development Multiple Screens (Low Range)

• The approximate 6,500 CBNG wells are about 65 

percent fewer than the other action alternatives, resulting 

in less overall impacts.

• The effects on aquatic resources would be similar in 

nature to Alternative F, but substantially less than 

Alternative F. 

• About 0.78 billion cubic feet of CBNG production water 

managed through flexible management options, but 

limits the volume of untreated water discharged to 

surface waters. 

• MPDES Permits would provide assurances that water 

quality, aquatic resources and beneficial uses of 

receiving waters would be protected.

• Limits CBNG development and total disturbed habitat 

annually and by watershed.

• Sequential and controlled development schedule, 

combined with watershed-level analysis, provides a 

framework for assessing potential impacts through a 

systematic monitoring program

• Incorporates Adaptive Management approach in the 

phased development process that uses the monitoring 

data. 

Alternative H

Preferred Alternative - Multiple Screens

• The same types of impacts described for Alternative A

would occur under Alternative H, but the impacts would 

occur on a far greater scale because of the development 

of over 18,000 CBNG wells.

• The potential for affecting aquatic resources would be 

similar to Alternative F . 

• About 2.24 billion cubic feet of CBNG production water 

managed through flexible management options, but 

limits the volume of untreated water discharged to 

surface waters based on water quality monitoring. 

• MPDES Permits would provide assurances that water 

quality, aquatic resources and beneficial uses of 

receiving waters would be protected.

• Unlike alternatives F and G, which set specific limits on 

the number of CBNG development by watershed, 

Alternative H uses water quality and quantity criteria to 

manage the number of CBNG wells in the various 

watersheds

• Incorporates Adaptive Management approach in the 

development process that uses the monitoring data.

Assumptions

The BLM has identified numerous mitigation measures

in Chapter 2 that would be implemented to avoid or 

minimize impacts on biological resources and 

hydrological features resulting from CBNG

exploration, production and abandonment activities on 

BLM-administered surfaces. These measures are 

common to all of the alternatives being analyzed in this 

EIS and are derived from current BLM leasing 

stipulations (contained in Minerals Appendix, Table 

MIN-5), standard operating procedures and BMPs and

State of Montana field orders. Several of the mitigation 

measures related to aquatic resources are briefly 

reviewed here for reader reference prior to discussing 

potential impacts and impacts that would be avoided or 

minimized, assuming the successful implementation of 

these mitigation measures. 

A key mitigation measure that directly affects aquatic 

resources is that the Montana and Wyoming Water 

Quality Agreement, which is pending final approval, 

would preserve the current water quality in the Tongue 

River and prevent Wyoming operators from 

discharging poor quality production water into the 

Tongue River. Examples of other mitigation measures

related to aquatic resources that are referenced in 

Chapter 2 and described in Table 4-67 of the Wildlife 

section include a prohibition on the surface occupancy 

or use of water bodies and streams, riparian areas and

100-year floodplains of major rivers, streams and

water bodies. In addition, surface occupancy and use is 

prohibited within 1/4 mile of designated reservoirs 

with fisheries, to protect the fisheries and recreational 

values of reservoirs. 

Specific mitigation measures are directed at protecting 

water quality and aquatic resources in drainages by 

controlling erosion and sediment delivery, particularly 

on steep slopes and during wet times of the year; 

minimizing the number of stream crossings; 
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reclaiming, reseeding and revegetating disturbed areas; 

and maintaining a Spill Prevention Control and 

Countermeasures (SPCC) Plan to deal with accidental 

spills and control storm water run-off. A number of 

mitigation measures that would be applied on a caseby-case basis, as needed, are described in Appendix 

Table MIN-5. Examples of mitigation measures 

associated with aquatic resources, some of which are 

directed at special status species, include 

considerations of the location and timing of stream 

crossings as they relate to fish spawning periods and 

habitat and the minimization or avoidance of inchannel activities to reduce the potential for habitat 

loss. The reader is referred to Chapter 2, Table 4-67 

and Minerals Appendix, Table MIN-5 for a complete 

listing of all mitigation measures. 

These mitigation measures would avoid some of the 

impacts that may otherwise occur on BLMadministered surfaces in the absence of such measures, 

but they do not apply to CBNG-related activities on 

non-BLM-administered surfaces and therefore would 

not avoid impacts on non-BLM-administered surfaces. 

The only management objective that applies to BLMadministered surfaces and lands subject to state 

regulations is the required placement of untreated 

waters from exploration activities in holding pits, 

tanks, or reservoirs, with no discharge to waters of the 

United States allowed. 

CBNG exploration, production and abandonment 

activities would potentially impact aquatic resources in 

a number of ways. The likelihood of these impacts 

occurring depends on the exact nature, location and

timing of CBNG activities; the proximity of CBNG 

activities to water bodies and the presence of sensitive

species and/or sensitive life stages in these water 

bodies; and the nature of mitigation measures that 

would be implemented to minimize, avoid, or mitigate 

the potential occurrence of impacts. The success of 

these actions requires and assumes a site-specific 

understanding of the resources to be protected and 

adherence to mitigation measures during CBNG 

activities. The assumptions stated in the Hydrological 

Resources section of this chapter also form a portion of 

the framework for analyzing potential impacts from 

CBNG activities on aquatic resources.

The discussion of impacts in the following text for the 

No Action Alternative first describes the types of 

impacts that would result from CBNG activities in the 

absence of mitigation measures. It then assesses the 

likelihood of such impacts occurring based on the 

nature and magnitude of CBNG activities, the 

proximity of those activities to aquatic resources and

the rigor of mitigation measures that would be 

implemented on lands managed by BLM and on lands 

subject to state regulations. Conclusions address the 

residual impacts that would remain following the 

implementation of mitigation measures. Conclusions 

also address the cumulative impacts that would result 

from the residual impacts of CBNG development 

combined with the potential effects of other projects in 

the area.

Many of the same types of direct and indirect impacts 

on aquatic resources would occur regardless of the 

number of CBNG wells developed, although the 

magnitude of impact would vary. Many of the same 

types of mitigation measures also would be 

implemented. Therefore, the detailed discussions of 

types of impacts first presented for the No Action 

Alternative are referenced, as appropriate, in 

subsequent discussions of impacts for Alternatives B

through H. The potentially greater magnitude and 

geographic extent of impacts on aquatic resources

because of the substantially greater number of CBNG

wells that would be developed under Alternatives B 

through H are discussed under those alternatives. 

Impacts from Management Common to All 

Alternatives

Types of impacts on aquatic resources, including fish, 

aquatic invertebrates and their habitat, potentially 

resulting from CBNG development activities would be 

similar to those described for oil and gas exploration 

and development activities (MBOGC 1989). These 

include direct removal of habitat, habitat degradation 

from sedimentation, altered spawning and seasonal 

migration because of stream obstructions, direct loss of 

fish from accidental spills or pipeline ruptures 

releasing harmful substances, increased legal harvests 

of fish because of increased human access and reduced 

stream flows because of removing water for drilling 

activities. These potential types of impacts are 

common to all alternatives and are described further 

under Alternative A (the No Action Alternative). An 

additional impact on aquatic resources that would only 

occur under all alternatives except B is the potential for 

altered stream water quality and/or increased flows in 

those instances when production water is discharged to 

drainages. This impact also is described under the No 

Action Alternative. However, no impacts would result 

from conventional oil and gas activities because of 

protection of reservoirs on 1,844 acres.
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Impacts from Management Specific to 

Each Alternative

Alternative A—No Action (Existing CBNG 

Management)

Numerous irrigation-related or naturally occurring 

dewatering problems that affect aquatic resources have 

been identified for drainages in the Billings RMP and 

Powder River RMP areas that would continue under 

the No Action Alternative. These problems were 

described in discussions of the affected environment 

and are not CBNG-related. In the Billings RMP area, 

these include periodic dewatering of portions of the 

Yellowstone River and downstream sections of the 

Clarks Fork and Bighorn rivers and chronic dewatering 

of the Boulder River, the upstream section of the 

Clarks Fork, portions of the Musselshell River and

Careless Creek. In the Powder River RMP area, 

dewatering problems include periodic dewatering of 

the downstream section of the Tongue River and 

chronic dewatering of the Powder River. Dewatering 

indicates a reduction in streamflow, usually during the 

irrigation season (July through September), beyond the 

point where stream habitat is adequate for fish. 

Periodic dewatering indicates a crucial problem in 

drought or water-short years and chronic dewatering 

indicates a critical problem in virtually all years 

(Montana State Library NRIS 2005).

The two most common forms of water quality effects 

in the Billings RMP and Powder River RMP area 

drainages are from elevated sediment and salinity 

concentrations, primarily from non-point sources 

related to agricultural practices (MBOGC 1989). 

Levels of dissolved solids in drainages tend to increase 

proceeding downstream because of contributions from 

irrigation return flows, increased base flows that have 

been in contact with soil and rocks for long periods of 

time and effects of human activities. Water in 

intermittent and ephemeral drainages often is of poor 

quality because of the sudden and highly variable 

nature of discharge (snowmelt, intense rainstorms) that 

would result in elevated turbidity, dissolved solids and

suspended sediment levels in these and in downstream 

perennial drainages (MBOGC 1989). These water 

quality conditions would likely continue under the No 

Action Alternative.

Fish populations and habitat in perennial and 

intermittent streams in the Billings RMP and Powder 

River RMP areas are impacted by drought, high 

temperatures, prolonged cold, heavy icing and flooding 

(BLM 1995). Pond habitat and fisheries in the RMP 

areas also would be affected by dry, low-water years 

when excessive water temperatures and reduced 

dissolved oxygen levels during summer would kill fish

and by extended periods of ice and snow and 

subsequent oxygen depletion during winter that would 

kill fish (BLM 1995).

Previous studies have summarized the ways in which 

aquatic resources, including fish, aquatic invertebrates

and their habitat, would potentially be impacted, either 

directly or indirectly, by CBNG activities (BLM 1992; 

USDI 2000; Regele and Stark 2000). Many of these 

impacts are the same as described for oil and gas 

exploration and development activities (MBOGC 

1989). They include the following effects:

• Loss of aquatic and riparian habitat at stream 

crossings and near well sites

• Habitat degradation and loss from increased 

sediment delivery and sedimentation

• Altered spawning and seasonal migrations of fish 

because of stream obstructions

• Direct loss of fish and aquatic invertebrates from 

accidental spills, leakage and runoff of harmful 

substances into drainages

• Increased legal and possibly illegal harvests of 

fish because of increased human presence

• Altered water quality and increased stream flows 

from discharging CBNG production water into 

nearby drainages

While roads do not affect all species and ecosystems 

equally, the overall presence of roads is highly 

correlated with changes in species composition, 

population sizes and hydrologic and geomorphic 

processes that shape aquatic and riparian systems. All 

types of roads affect aquatic ecosystems in several 

general ways: (1) increased mortality from road 

construction, (2) alteration of the physical 

environment, (3) alteration of the chemical 

environment, (4) spread of exotic species and (5) 

increased alteration and use of habitats by humans 

(Trombulak and Frissell 2000).

Crossing streams and placing facilities such as 

culverts, bridges and cattle guards during the

construction or upgrading of access roads to well sites 

would result in the localized loss of aquatic and 

riparian habitat. Depending on stream location and 

hydrology, drainages may provide year-round 

(perennial) or seasonal (intermittent or ephemeral) 

habitat for a variety of fish species and their life stages, 

including spawning, incubating, rearing, holding and

over-wintering. Drainages also provide habitat for 

aquatic macro- and micro-invertebrates that are 

typically important fish foods, such as aquatic insects, 
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zooplankton, clams, snails and worms, as well as 

habitat for aquatic plants, including periphyton, 

phytoplankton and vascular macrophytes. Instream 

activities also would alter habitat characteristics such 

as water depth, velocity and habitat types that are 

important to native and introduced fish species as well 

as benthic invertebrates. 

The loss of riparian habitat would be especially 

important in smaller drainages because of its many 

influences on the quality of aquatic habitat. Murphy 

and Meehan (1991) reported that riparian habitat can 

form a protective canopy that provides overhead cover 

for fish and moderates the extreme effects of air 

temperatures during summer (helps to cool streams) 

and winter (helps to insulate streams). Riparian habitat 

also helps reduce soil erosion and filters sediment 

before it enters streams, stabilizes streambanks and

allows for the formation of undercut banks that provide 

cover for fish. In addition, riparian habitat contributes 

litter (nutrients and food for invertebrates) and woody 

debris (instream cover) to drainages and it provides 

habitat for insects that fall to the water’s surface and 

are consumed by fish (Murphy and Meehan 1991). The 

loss of these riparian functions would result in impacts 

on aquatic resources.

Soil disturbance, erosion and runoff during CBNG

activities would result in increased sediment delivery 

to streams and the degradation or loss of aquatic 

habitat. Examples of such activities include the 

construction, upgrading, use, maintenance and

retirement of access roads; the installation of culverts, 

bridges and cattle guards at stream crossings; other 

instream activities such as fording streams; site 

preparation, well drilling and related onsite facilities; 

and the construction and placement of pipelines for gas 

delivery. The potential for erosion and runoff would be 

greatest where wet or moist soils on steep slopes with 

little or no vegetative cover have been compacted by 

heavy equipment (BLM 1992). 

Increased sediment delivery to drainages would affect 

aquatic resources through the sedimentation of habitat 

and increased levels of turbidity and suspended 

sediment in the water column. Increased sedimentation 

would cause a reduction or elimination of stream 

bottom habitat used by aquatic insects such as 

caddisflies, mayflies and stoneflies; a subsequent 

reduction in aquatic insect abundance and diversity; a 

reduction in the permeability among interstitial spaces 

within spawning gravels that inhibits the flow of welloxygenated water and the removal of metabolic 

wastes; a subsequent reduction in spawning success, 

hatching success and fish production; and a reduction 

in the interchange of surface and subsurface waters in 

the hyporheic (mixing) zone beneath the stream 

channel (Nelson et al. 1991; USDI 2000). Substantially 

increased sedimentation would eliminate or reduce the 

depths of pools that provide important year-round 

cover for juvenile, sub-adult and adult fish and would 

cause the premature siltation of beaver ponds, which 

often provide year-round habitat for trout (MBOGC 

1989). If severe enough, increased sediment loads 

would cause the erosion and migration of stream 

channels (Chamberlin et al. 1991) and the degradation 

of aquatic and riparian habitat.

Elevated turbidity and suspended sediment levels 

caused by increased sediment delivery would have 

sublethal and acute effects on fish. Nelson et al. (1991) 

reported that suspended sediment concentrations of 

1,200 mg/l can cause mortalities in under yearling 

salmonids, while suspended sediment concentrations 

as low as 100 mg/l up to 1,000 mg/l are sometimes 

associated with a general reduction in fish activity, 

impaired feeding, reduced growth, downstream 

displacement and decreased resistance to other 

environmental stressors. MBOGC (1989) reported fish 

and fish food production would be affected by the 

abrasive effects of very fine sediment on fish embryos 

and fry and on immature aquatic insects. In addition, 

very turbid waters would exhibit increased 

temperatures because of the water’s capacity to retain 

more heat. This would affect those fish and 

invertebrate species with the most restrictive coldwater or cool-water thermal requirements. 

The most severe aquatic impacts resulting from 

increased sediment delivery would be to trout, 

whitefish and grayling. These species have relatively 

narrow habitat requirements, including the need for 

clean, cold, well-oxygenated water and/or gravels for 

spawning, egg incubation, rearing and adult success 

(Bjornn and Reiser 1991). The MBOGC (1989) 

generally concluded that in Montana, increased 

sediment delivery would have a greater impact on 

aquatic resources in high-gradient mountain streams 

than in low-gradient prairie streams. Mountain streams 

typically support the very sensitive and highly valued 

species of salmonids, which are generally much less 

tolerant of increased sediment and turbidity levels than 

are the warm water fish species found in the lowergradient prairie streams and rivers in Montana. The 

MBOGC (1989) also noted that the potential for 

impacts from sediment delivery to drainages may be 

greatest in mountainous terrain because roads and 

pipelines are typically constructed close to streams 

where slopes are less steep.

Fish spawning migrations and localized movements 

would be affected in the event of improper placement, 

misalignment, or construction of culverts and bridges. 

Improperly designed facilities would block fish 

passage directly or constrain fish movements by 

creating hydraulic barriers caused by excessive water 
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velocities or insufficient water depths. Furniss et al. 

(1991) reported that unless properly designed, stream 

crossings would be considered dams that are designed 

to fail, with subsequent impacts on fish passage and 

the sedimentation of habitat. Four aspects of culvert 

design, including diameter, length, slope and vertical 

drop to the water’s surface, can potentially affect fish 

passage, especially of smaller fish. The MBOGC 

(1989) reported that perched culverts or small-diameter 

culverts with high water velocities effectively block 

trout spawning migrations. Bell (1986) stated that 

improperly designed culverts may preclude the passage 

of small fish and possibly discourage larger fish from 

attempting passage.

Accidental spills, leakage and runoff or leaching of 

petroleum products, drilling fluids stored in reserve 

pits and other potentially harmful substances such as 

CBNG production water (discussed further below) to 

surface water drainages may have acute and chronic 

effects on fish and their foods (BLM 1992; USDI 

2000). These effects are influenced by the nature of the 

substance including its persistence and fate, volume of 

spill, distance from surface water and likelihood of 

entry, the volume and diluting ability of the receiving 

water and sensitivity of organisms exposed to the 

substance. Direct effects can include mortalities of 

aquatic organisms, while indirect effects may be 

exhibited through chemically induced changes in 

densities and community structures of aquatic 

organisms (Norris et al. 1991). Examples include

alteration of environmental characteristics such as 

cover, food, or some other variable important to the 

well-being of fishes. Effects would be comparatively 

greater during low-flow than high-flow periods and in 

smaller rather than larger water bodies. The MBOGC 

(1989) concluded that the potential for impacts from 

accidental spills may be greatest in headwater 

mountain streams with relatively low flows because 

soils in such areas are often porous and runoff to 

streams is direct and rapid. 

Increased human access because of new roads and 

increased human activity associated with CBNG

exploration and production may result in increased 

legal and illegal harvest of fish from nearby drainages 

(MBOGC 1989). Besides angling mortalities of game 

species, legal fishing activities may result in the 

trampling of eggs and recently emerged fry from 

wading in streams and walking on or next to 

streambanks may cause increased bank erosion and 

habitat sedimentation. 

As discussed in the Hydrological Resources section, 

surface water bodies should not be impacted directly 

from groundwater withdrawal due to the depth and 

confined nature of the individual coal seams. In the 

unlikely event that there is a very localized connection 

between a spring-fed stream and groundwater 

withdrawals, examples of resultant habitat 

modifications that could impact fish and invertebrates 

include reduced water depths; slower water velocities; 

fewer and/or shallower pools and riffles; increased 

water temperatures during summer; exposed stream 

channel bottom and stream banks; reduced habitat for 

spawning, rearing, holding and refugia; reduced 

riparian habitat quantity, quality and function; and 

reduced fish and invertebrate production. 

Several examples illustrate the potential effects, or in 

the case of the proposed project, the anticipated 

absence of effects, of groundwater withdrawals on 

surface water hydrology and aquatic resources. The 

Southern Ute DEIS (USDI 2000) noted the potential 

for decreased surface water flows because of CBNG

production water withdrawals from groundwater 

aquifers on the Southern Ute Reservation in New 

Mexico and Colorado. That analysis estimated that 

between 1,600 and 2,500 acre-feet of water may be lost 

from instream flows and concluded that this was not 

anticipated to impact fish habitat. This is equivalent to 

a 2.2 to 3.5 cfs reduction in instream flows spread 

evenly over a year. Under other circumstances and 

depending on the size of the drainage potentially 

affected, a flow reduction of about 3 cfs would have 

substantive effects on very small perennial and 

intermittent drainages, but negligible effects on very 

large perennial drainages. Studies also were conducted 

for the Deer Creek Coal Bed Methane Project, which is 

in the Tongue River watershed in the northwestern part 

of the Powder River Basin (BLM 2000a). Hydrologic 

analysis of the Deer Creek Project, like the hydrologic 

analysis in this EIS, indicated that because of the 

sealing effect of the overlying aquitards, water levels 

in shallow aquifer zones and in shallow wells in the 

Planning Area would not be impacted by water level 

drawdowns caused by CBNG well operations (BLM 

2000a). The Deer Creek analysis concluded that flows 

and aquatic habitat in Planning Area drainages should 

not be depleted or aquatic habitat degraded. Similar 

findings were presented for studies of the Castle Rock 

Project, which concluded that cumulative impacts on 

the surface water resources of the exploration area, 

which include the Powder River and Pumpkin Creek, 

are expected to be minimal to nonexistent in the short 

term (BLM 2000b). 

Aquatic resources would be affected by the discharge 

to surface waters of groundwaters that are withdrawn 

during CBNG production activities. The discharge of 

groundwaters would alter surface water quality and 

increase flows, potentially impacting aquatic habitat 

and biota. The effects of production water discharge 

would be most evident in smaller drainages during 

low-flow times of the year, particularly in those 
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drainages with low levels of TDS. The specific ionic 

constituents comprising TDS are also important 

determinants of a water body’s effect on aquatic 

organisms. For purposes of comparison, fresh water

usually has a salinity of less than 500 mg/l while sea 

water has an average salinity of 35,000 mg/l. The 

surface discharge and runoff of production water also 

would cause erosion of soils and even higher 

concentrations of solids. Examples of TDS 

concentrations in groundwater found in coal aquifers 

of the Powder River Basin were presented previously 

in the Hydrological Resources section of this 

document and ranged from 401 to 2,646 mg/l. 

Based on the mitigation measures and assumptions 

described earlier, relatively few impacts on aquatic 

resources would be expected from exploration 

activities at 400 CBNG wells on BLM-administered 

lands under Alternative A. However, short-term 

impacts on aquatic resources resulting from CBNG

exploration activities on BLM-administered lands 

would include increased sediment delivery to nearby 

drainages during runoff events. Fish passage would 

also be impeded if culverts or bridges are used to cross 

drainages and are inappropriately placed. In addition, 

there is the potential for the accidental spill or leakage 

and entry of petroleum products into drainages 

associated with vehicles using the access roads and 

present at exploration sites. Increased access and 

human presence during exploration activities also may 

result in some increased harvest of game fish. There 

would be no anticipated change in streamflow volumes 

by exploration activities since these activities would 

not discharge production waters into surface drainages. 

Any untreated waters from exploration would be 

placed in holding pits, tanks, or reservoirs, with no 

discharge to waters of the United States allowed.

As noted in the earlier discussion of wildlife resources, 

nearly all of the mitigation measures for CBNG 

activities on BLM-administered surfaces do not apply 

to CBNG activities on non-BLM-administered surfaces 

(i.e., lands subject to state regulations). Therefore, the 

absence of mitigation measures that prohibit the 

occupancy or use of water bodies, floodplains and

riparian areas on lands subject to state regulations 

increases the likelihood that exploration activities at 

275 CBNG wells on state-regulated lands within or 

immediately adjacent to these habitats would have a 

greater potential for impacting aquatic resources than 

on BLM-managed lands. These impacts would be in 

addition to those described in the preceding text for 

exploration activities on BLM-administered surfaces. 

However, the magnitude of these impacts would 

probably still be minor because of the somewhat 

limited nature of exploration activities. There would 

continue to be the potential for increased sediment 

delivery, possible impedance of fish movements in 

streams, potential for accidental spills of petroleum 

products and possibly increased fish harvest. However, 

there would be no effect on stream flow volume. In 

addition, as noted for exploration activities on BLMadministered surfaces, there would be requirements for 

placing untreated exploration water in holding pits, 

tanks, or reservoirs, with no discharge to waters of the 

United States allowed. 

The State of Montana has stressed the importance of 

protecting high-value recreational fish populations 

that occur in drainages in the CBNG Planning Area. 

It is expected that the state would not allow 

exploration activities to be conducted in a manner 

that would impact these highly valued fisheries. They 

include trout fisheries and populations of other 

important species of game fish, particularly in those 

drainages in each county that have been judged by the 

State of Montana to support a resource of national 

renown and to have outstanding, high, or substantial 

fisheries resource values.

Under the No Action Alternative, CBNG production 

would only occur on the CX Ranch, where there are no 

specific mitigation measures for CBNG production 

activities. Because of this, potential impacts from the 

development of 250 producing CBNG wells on the CX 

Ranch would generally include the same impacts that 

were described for exploration activities on lands 

subject to state regulations, although they would 

extend over a longer period of time. Discharge of 

production water from these wells would be regulated 

by the MDEQ via a MPDES permit, which would 

allow 1,600 gallons per minute (gpm) discharge into 

the upper Tongue River from up to 11 discharge 

points. During Water Year 2005, the average CBNG 

produced water discharge to the Tongue River in 

Montana was approximately 1,067 gpm upstream of 

the Tongue River Reservoir (MBMG 2005). However, 

current permits (as of February 2006) allow 3,300 to 

4,200 gpm upstream of the reservoir (varying by 

season) and an additional 1,122 gpm downstream of 

the reservoir (see the Hydrological Resources section 

in Chapter 3).

The TDS concentration in CBNG-produced water from 

the CX Ranch is about 1,400 mg/l, while Regele and 

Stark (2000) reported the average TDS concentration 

for the Tongue River is 284 mg/l. The resultant TDS 

concentration from discharging 3.6 cfs (approximately 

1,600 gpm) of production water (1,400 mg/l TDS) to 

the Tongue River with a flow of 39 cfs (284 mg/l TDS) 

would be 378 mg/l TDS. This represents a 94 mg/l 

increase in TDS over background levels, but it is still 

well below the TDS guideline of 1,000 mg/l associated 

with possible effects on fish. Resultant water 

temperatures would likely be similar to that of the 
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Tongue River upstream of the mixing zone because of 

the predominance of river flow. This would not be the 

case when there is very low or sometimes no 

background flow in the Tongue River, as is the case 

during critical drought periods. Under the very worstcase conditions, the only flow in the river would 

theoretically consist of CBNG produced water with a 

TDS concentration of approximately 1,400 mg/l that 

has been discharged to the river. While this TDS value 

would exceed the 1,000 mg/l TDS concentration 

associated with possible effects on aquatic organisms, 

it would be the only source of water in the drainage 

and probably provide at least some refuge for aquatic 

organisms until background flows return. Water 

temperatures may initially be somewhat cooler than 

would normally occur during low-flow periods, but 

they would likely increase proceeding downstream in 

response to local climatic conditions.

This same type of analysis can be done by evaluating 

the effect of produced water and the dilution effect of 

Tongue River water using bioassays and predictive 

modeling. However, the results of bioassays differ 

substantially from and show far fewer effects on aquatic 

organisms than suggested by predictive modeling. The 

Mount et al. (1997) model would predict that the 

produced water from the CX Ranch wells would be 

lethal to 100 percent of fathead minnows. Once the 

water is discharged to the Tongue River, the dilution 

would be such that there would be no increase in 

toxicity to fish in the river. The model would indicate 

that if there was no or very little dilution of this 

discharge by either flowing or standing river water, it 

would be toxic to fish and aquatic invertebrates. 

Results of actual whole effluent toxicity testing using 

fathead minnows and a cladoceran (water flea), 

Ceriodaphnia dubia, showed far fewer or no 

mortalities than predictive modeling. A representative 

sample of effluent from Fidelity Exploration & 

Production Company coal bed natural gas wells that 

discharges to the Tongue River and of Tongue River 

receiving water collected immediately upstream of the 

effluent outfall were used in whole effluent toxicity 

testing. Acute toxicity tests (96 hours for fathead 

minnows and 48 hours for Ceriodaphnia) were 

conducted at Energy Laboratories, Inc. (2001) in 

Billings Montana, from March 22 through March 26, 

2001, in accordance with Region VIII EPA guidelines. 

Six dilutions were used during whole effluent toxicity

testing with percent effluent in each dilution at 0 

percent (pure receiving water control), 12.5 percent, 25 

percent, 50 percent, 75 percent and 100 percent (pure 

effluent). The effluent passed the 50 percent mortality 

test for both species tested, indicating there would be 

no mortalities at equal parts of effluent (or less) and 

receiving river water. At effluent levels of 75 and 100 

percent, fathead minnow survival after 96 hours was 

85 percent and 60 percent, respectively. Ceriodaphnia 

survival after 48 hours at effluent levels of 75 and 100 

percent was 95 and 80 percent, respectively (Energy 

Laboratories, Inc. 2001). These test results generally 

indicate some mortalities of fish and insects could 

occur when the volume of effluent constitutes more 

than 50 percent of the flow in a drainage.

Experiments have shown that increased bicarbonate 

concentrations (sodium bicarbonate from CBNG 

produced water) appears to have greater toxicity to 

some fish than was previously estimated (Skarr et al 

2005). Studies of newly hatched fathead minnows 

showed mortality when exposed to waters with 

bicarbonate concentrations greater than 400 mg/l. 

While white suckers show improved hatching and 

early survival rates at bicarbonate concentrations as 

high as 1,400 mg/l when compared to control groups. 

However, at higher concentrations (between 4,049 and 

6,678 mg/l) the percent mortality of white suckers was 

as much as 50 percent (Skarr et al 2005). CBNG 

produced waters in the Tongue and Powder River 

watersheds have average bicarbonate concentrations of 

approximately 1,000 to 1,500 mg/l (Skarr, 2006). 

In addition to untreated produced water discharge 

volumes, two additional permits were submitted to 

MDEQ for the discharge of treated water to the 

Tongue River (MBMG 2005) and subsequently 

approved. One of these permits would allow for 

discharge upstream of the Tongue River Reservoir 

(1,700 gpm) and the other for discharge downstream of 

the reservoir (1,122 gpm). The combined CBNG water 

discharges would result in a total of 7.6 cfs of 

increased flows to the river, or about 10 percent of the 

7Q10 flow at Brandenburg Bridge. 

The abandonment of exploratory and producing wells 

would have few, if any, direct or indirect impacts on 

aquatic resources. Activities that impact aquatic habitat 

and biota during CBNG exploration and production 

phases would cease with CBNG abandonment. Any 

associated long-term effects on aquatic resources from 

these discontinued activities, such as sediment delivery 

from roads, would gradually subside as disturbed areas 

are reclaimed.

Special Status Species

The federally endangered pallid sturgeon and one

federal candidate species (Montana Arctic grayling) 

are present in portions of the Planning Area. Also 

present in portions of the Planning Area are seven 

BLM-sensitive and/or state fish species of special 

concern, including sturgeon chub, blue sucker, sauger, 

northern redbelly dace x finescale dace hybrid, 

paddlefish, pearl dace and Yellowstone cutthroat trout.
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Distribution of these species was described in Chapter 

3 discussions of the affected environment for aquatic 

resources. The affected environment for special status 

amphibians and aquatic dependent reptiles is discussed 

in the wildlife section of Chapter 3 and the potential 

impacts to these species from the project alternatives 

are presented in the wildlife section of Chapter 4. 

Because of their scarcity or narrow habitat niche, these 

special status species may be somewhat more 

vulnerable to potential project effects than were 

described above for all aquatic resources. However, the 

potential for affecting any of the federally listed, 

candidate, significant concern, BLM-sensitive, or state 

species of concern would generally be similar to that 

described in the preceding text for other aquatic 

species and would either be low or absent. For 

example, all water from exploration activities would be 

captured in tanks and not discharged to rivers. In 

addition, conditions of MPDES Permits would provide 

legally enforceable assurances that water quality, 

aquatic resources and the beneficial uses of receiving 

waters would not be degraded by production water 

discharges. Some impacts could potentially occur, 

however, during extreme low or no flow conditions. 

Release of adequate quality water from production 

may improve habitat that has been degraded through 

water withdrawals. The range and type of other 

potential effects discussed above for aquatic resources 

also apply to special status species since they are a 

subset of aquatic resources. Special status species 

could be minimally affected through construction of 

stream crossings, erosion generated by construction 

activities and effects of other activities discussed above 

for aquatic resources.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative A. However, 

regulations mentioned above related to aquatic 

resources would be under the jurisdiction of tribal laws 

and not state or federal laws. CBNG development on 

the Crow Reservation is expected to be very limited. 

To the extent that it does occur, potential impacts on 

aquatic resources would be similar to those described 

for private lands and would occur on a much smaller 

scale than on BLM or State lands. If there were no 

CBNG development on tribal Lands, then there is 

expected to be minimal impacts on aquatic resources 

on the reservation. CBNG development in Wyoming 

could impact surface waters on the reservation and 

could have an effect on aquatic life. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described in general for 

Alternative A. CBNG development on the Northern 

Cheyenne Reservation is expected to be very limited. 

To the extent that it does occur, impacts on aquatic 

resources would be similar to those described for 

private lands and would occur on a much smaller scale 

than on BLM-administered or State lands. If there were 

no CBNG development on tribal Lands, then there is 

expected to be minimal impacts on aquatic resources 

on the reservation. CBNG development in Wyoming

could impact surface waters on the reservation and 

could have an effect on aquatic life. However, the 

pending Montana and Wyoming Water Quality 

Agreement would preserve the current water quality in 

the Tongue River and prevent Wyoming operators 

from discharging poor quality production water into 

the Tongue River. The Tongue River borders the 

reservation on the east.

Conclusions

Relatively few residual impacts on aquatic resources, 

including the special status species, would be expected 

from exploration activities on BLM-managed lands. 

Some minor, short-term impacts on aquatic resources 

on BLM-administered surfaces may result from 

increased sediment delivery, possible impedance of 

fish movements in streams, potential for accidental 

spills of petroleum products and possibly increased 

fish harvest. Residual impacts on aquatic resources 

from exploration activities on lands subject to state 

regulations would be similar to these impacts, although 

possibly slightly greater in magnitude because of the 

lack of mitigation measures prohibiting surface 

occupancy or use of water bodies, floodplains, riparian 

areas and steep slopes. Expected impacts on aquatic 

resources on state-regulated lands would still be 

relatively minor because of the limited nature of 

exploration activities and their dispersed pattern over a 

large geographic area. Residual impacts from 

developing 250 CBNG wells on the CX Ranch would 

include the same potentially minor kinds of impacts 

that were described for exploration activities on lands 

subject to state regulations, although they would 

extend over a longer period of time. The effects of 

discharging production water from these wells to the 

upper Tongue River drainage basin would cause river 

flow to increase from about 39 cfs to 43 cfs and river 

TDS concentration to increase from 284 mg/l to 378 

mg/l. These increases would not be expected to impact 

aquatic habitat or organisms in the Tongue River. In 

addition, the conditions of the MPDES Permit would 

provide legally enforceable assurances that water 

quality, aquatic resources and the beneficial uses of 

receiving waters would not be degraded by production 

water discharges. Discharges of CBNG produced water 

during extreme drought conditions of no background 

flow (worst-case conditions) would probably provide 
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some refuge for aquatic organisms, even though TDS 

concentration would be approximately 1,400 mg/l and 

water temperatures would initially be cool but 

increase. There also could be some mortalities of 

aquatic organisms, as indicated by results of whole 

effluent toxicity WET testing, under these extreme 

conditions. The abandonment of CBNG wells would 

have few, if any, direct or indirect residual impacts on 

aquatic resources. Long-term effects on aquatic 

resources associated with discontinued activities, such 

as sediment delivery from roads, would subside as

disturbed areas are reclaimed. Agency mitigation 

measures implemented during abandonment would 

reduce erosion potential, prevent water quality 

degradation, facilitate reclamation of disturbed lands

and further reduce the potential for long-term impacts 

on aquatic resources, including special status species. 

Cumulative Impacts 

This assessment considers the potential cumulative 

impacts on aquatic resources resulting from the effects 

of the No Action Alternative together with the effects 

from five coal mines, two minerals/metals mines, five 

existing power plants, four oil and gas refineries, two 

manufacturing facilities and the proposed Tongue 

River Railroad that are present within the Planning 

Area. The greatest potential for impacts on aquatic 

resources from these other projects is probably from 

coal mines, both through the direct loss of habitat and 

the degradation of water quality. Surface water quality 

near coal mines is impacted by increased sediment 

load because of increased erosion during mining. This 

is mitigated by the use of sediment settling ponds and 

the vegetation of overburden and topsoil storage areas. 

The discharge of groundwater pumped from mine pits 

also may affect surface water quality and quantity, 

depending on the quality of groundwater within the 

mine vicinity and the quantity of groundwater 

discharged. Aquatic resources associated with nearby 

springs and surface streams within the area could be 

impacted by the lowering of water tables from mining 

activities. In some instances, mining activities impact 

aquatic resources by diverting streams or drainage 

areas that are within the area to be mined. Original 

topography, including stream channels and drainage 

areas, are restored during mine reclamation activities. 

Some of these same types of impacts also may occur at 

minerals/metals mines, but would be less likely to 

occur at the power plant, oil and gas refinery and

manufacturing sites. 

Other possible impacts on aquatic habitat and biota 

from these projects include sediment delivery from 

access roads located near drainages, loss of riparian 

habitat and function along streams and reduction in 

water-based recreational activities such as fishing with 

the loss of aquatic habitat. The nature of effects on 

aquatic resources from these activities would be 

similar to those described for potential impacts under 

the No Action Alternative for CBNG development. 

Most of these impacts would be limited in area given 

the generally localized nature of these other projects. 

Their effects are typically mitigated by following 

standard construction and operating procedures and 

BMPs and by implementing reclamation activities 

during or following project construction, operation

and/or abandonment—the same as described for 

CBNG development under the proposed project. For 

these reasons, the effects from these other projects 

would not be expected to result in substantive 

cumulative impacts on aquatic resources potentially 

affected by CBNG development. 

Regele and Stark (2000) discussed some of the 

possible biological issues associated with CBNG gas 

development in Montana, including the effects of 

pumping and discharging production water from 

CBNG wells into surface drainages. They reported that 

much of the groundwater being produced from more 

than 3,000 CBNG-producing wells in the Wyoming 

portion of the Powder River Basin is being discharged 

into rivers that flow directly into southeastern 

Montana. These include the Powder and Little Powder 

rivers and their tributaries. Some potential short-term 

and long-term CBNG developmental effects identified 

by Regele and Stark (2000) include decreased surface 

water availability in some areas because of 

groundwater pumping; increased surface water flows 

in areas receiving CBNG discharges in other areas; and 

water quality effects of CBNG development discharges 

on waters and biota receiving the CBNG discharges. 

However, Wyoming EISs and EAs found no decrease 

in surface water because of aquitards between 

production coals and surface waters.

The Hydrological Resources impact analysis presented 

in this chapter evaluated the potential cumulative 

effects of full-scale CBNG development and discharge 

of produced water to the Powder River Basin in 

Wyoming. That analysis recognized the substantial 

flow increases and associated hydrologic and water 

quality impacts that would occur in the Powder, Little 

Powder and Tongue rivers in Montana as a result of 

those discharges. Impacts on aquatic habitat and biota 

from that magnitude of discharge also would be 

substantial. The Hydrological Resources analysis 

noted, however, that the WYDEQ and MDEQ have 

pledged to maintain water quality in these three rivers

and that surface water discharge permits limiting the 

quantity of CBNG-produced waters that would be 

discharged would mitigate impacts from Wyoming 

CBNG on Montana rivers. This action also would 

mitigate the potential for cumulative impacts on 
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aquatic resources from the effects of Wyoming CBNG

on Montana rivers.

The proposed Tongue River Railroad could impact 

aquatic invertebrates and fish through habitat 

disturbance and water quality impacts, such as 

temporary increases in sediment loading and TSS, 

caused by construction of bridges and portions of the 

rail line adjacent to the Tongue River. Increases in TSS 

may temporarily increase downstream drift of aquatic 

invertebrates, resulting in lower invertebrate 

populations in the construction area and deter fish 

movement through the construction zone. Increased 

sediment loading may also cause the irritation of the 

gills of sensitive fish species. One spawning area for 

smallmouth bass may be temporarily or permanently 

lost and spawning habitat for northern pike may also 

be impacted. During operation of the railroad, impacts 

to aquatic resources may caused by loss of aquatic 

habitat from alteration of the flood plain, use of 

herbicides and fuel or other hazardous material spills.

However, construction and operation of the railroad 

will be in accordance with all state and federal rules 

and regulations and will use mitigation measures and 

best management practices to minimize impacts to 

aquatic resources. 

Alternative B—Emphasize Soil, Water, Air, 

Vegetation, Wildlife and Cultural Resources

Most but not all of the same types of impacts on 

aquatic resources described for CBNG activities under 

Alternative A (No Action Alternative) would occur 

under Alternative B. These impacts and some of their 

effects include the direct removal of aquatic and 

riparian habitat at stream crossings and near well sites, 

habitat degradation and loss from sedimentation, 

altered spawning and seasonal migration because of 

stream obstructions, direct loss of fish and aquatic 

invertebrates from accidental spills or pipeline ruptures 

releasing harmful substances and increased harvests of 

fish because of increased human access. The 

magnitude and geographic extent of these impacts 

would potentially be greater under Alternative B than 

Alternative A because of the activities associated with 

the development of an estimated 23,850 CBNG 

production wells and 2,650 CBNG dry holes. There 

would be an estimated 7,621 production wells and 847 

dry holes on BLM-administered land, 8,849 production 

wells and 983 dry holes on state-regulated land, 7,200 

production wells and 800 dry holes on tribal land and

180 production wells and 20 dry holes on USFSadministered land. 

Impacts described under the No Action Alternative that 

are associated with the discharge of production water 

to drainages and resultant increases in stream flows 

and elevated levels of TDS and constituents would not 

occur under Alternative B. There would be a potential 

for the accidental spill, release, or seepage of 

production waters temporarily stored in holding ponds 

or tanks prior to their injection. However, as noted in 

the Hydrological Resources impact analysis, berms 

around these facilities would be designed to contain 

and prevent the accidental runoff to nearby drainages 

of stored production waters, which should minimize 

the potential for impacting aquatic habitat and 

resources. 

The Hydrological Resources impact analysis indicates 

based on the estimated groundwater depletions, those 

watersheds that may experience the greatest CBNG

development activity. The most active watersheds are 

projected to be the Little Bighorn and Lower Bighorn, 

Upper Tongue and Lower Tongue, Little Powder and 

Middle Powder, Mizpah and Rosebud, where an 

estimated 14 to 50 percent of the groundwater resource 

in the coal seams within a watershed would be 

depleted after 20 years. Even though few impacts on 

aquatic resources are projected under Alternative B, 

data on fish species present, fisheries management 

policies and fisheries resource values would be used to 

identify those watersheds and drainages that are 

probably most sensitive to the effects of CBNG 

development and should be monitored closely during 

CBNG activities. Based on these fisheries criteria, 

drainages probably most sensitive to the effects of 

CBNG development are the Lower Bighorn, Upper 

Tongue and Little Bighorn. The Lower Bighorn and 

Upper Tongue are managed as trout fisheries and have 

high fisheries resource values, while the Little Bighorn 

is managed for warm/cool water fish species and trout

and has a moderate fisheries resource value. The 

Lower Tongue, Little Powder and Rosebud are 

probably less sensitive from a fisheries perspective, 

being managed as non-trout or undesignated fisheries, 

but they have high to substantial fisheries resource 

values. The Mizpah is probably the least sensitive of 

these drainages, being managed as a non-salmonid 

(warm water) fishery with a moderate to limited 

fisheries resource value.

Special Status Species

The types of impacts and potential project effects on 

special status species under Alternative B would 

generally be similar to those described in the preceding 

text for aquatic resources under this alternative. Many 

of these effects also would be similar to those 

described under Alternative A. However, they would 

be greater in magnitude and extent because of 

considerably more production wells and would 

primarily result from construction-related activities. 

No production water would be discharged to drainages 
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under Alternative B and there would be no resultant 

potential for affecting special status species. The 

overall likelihood of affecting special status species 

would probably be low or absent, depending on species 

distribution. However, as noted for Alternative A, 

these species may be somewhat more vulnerable than 

the more commonly-occurring aquatic species because 

of their limited distribution, low abundance and/or 

narrow habitat requirements.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative B. CBNG 

development on the Crow Reservation is expected to 

comprise a portion of the estimated 7,200 CBNG

production wells to be developed on tribal lands. To 

the extent that it does occur, potential impacts on 

aquatic resources would be similar to those described 

for private lands but would probably occur on a 

somewhat smaller scale than on BLM-administered or 

State lands. If there were in fact no CBNG 

development on the Crow Reservation, then there are 

expected to be minimal impacts on aquatic resources 

on the reservation. Until the tribe approves CBNG 

development on the reservation, a 2-mile wide buffer 

zone around the reservation would be enforced under 

Alternative B to minimize the potential for adjacent 

CBNG development to affect tribal aquatic resources. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described in general for 

Alternative B. CBNG development on the Northern 

Cheyenne Reservation is expected to comprise a 

portion of the estimated 7,200 CBNG production wells 

to be developed on tribal lands. To the extent that it 

does occur, impacts on aquatic resources would be 

similar to those described for private lands but would 

probably occur on a much smaller scale than on BLM 

or State lands. If there were no CBNG development on 

the Northern Cheyenne Reservation, then there are 

expected to be minimal impacts on aquatic resources 

on the reservation. Until the tribe approves CBNG 

development on the reservation, a 2-mile wide buffer 

zone around the reservation would be enforced under 

Alternative B to minimize the potential for adjacent 

CBNG development to affect tribal aquatic resources. 

Conclusions

The types of residual impacts that would persist for 

Alternative B are the same as described for Alternative 

A, with the following two exceptions. Impacts would 

occur on a far greater scale under Alternative B than 

Alternative A. Also, no CBNG-produced water would 

be discharged under Alternative B and there would be 

no potential for resultant residual impacts on aquatic 

resources, including special status species, from that 

particular activity.

When compared to Alternative A, there would be an 

increased risk for cumulative effects from CBNG 

activities associated with Alternative B, but the 

impacts would be less than Alternative C. In addition, 

the 1-mile-wide buffer around active coal mines under 

Alternative B would reduce the potential for 

cumulative groundwater drawdown impacts to result 

from coal mine projects. 

Alternative C—Emphasize CBNG 

Development

Impacts on aquatic resources associated with 

Alternative C would include all of those CBNG-related 

impacts described for Alternatives A or B, but they 

would be greater in magnitude. The intensity and 

geographic extent of CBNG exploration, production

and abandonment under Alternative C would be the 

same as described for Alternative B. However, 

Alternative C emphasizes CBNG exploration and 

development with minimal restrictions and it would 

disturb many more acres (101,000 acres short-term, 

69,000 acres long-term) than Alternative B (80,000 

acres short-term, 48,000 acres long-term). Alternative 

C contains the same set of mitigation measures as 

Alternative B, whose benefits were described earlier 

and which were listed in Chapter 2. However, unlike 

Alternative B, CBNG exploration and production 

water under Alternative C would be discharged, 

untreated, onto the ground’s surface where it would 

subsequently enter surface water drainages. There 

would be no requirement for injecting CBNG 

production water into the ground, for treating water 

prior to its discharge, or for preparing a site-specific 

water management plan. Discharged CBNG water 

would be available for beneficial uses by industry, 

landowners, agriculture and for wildlife if of suitable 

quality. 

The effects of increased TDS concentrations would 

probably be greater on the more sensitive species of 

salmonids in headwater mountain streams than on 

native fish species in prairie streams that have evolved 

in an environment of naturally higher TDS levels. In 

addition, sensitive species of salmonids and non-native 

warm water fish that have not evolved in highly saline 

water but that now reside in prairie streams also would 

be at risk. These species may be particularly vulnerable 

because TDS levels are generally already high in 

prairie streams, thereby increasing the potential for 

TDS-related impacts from CBNG production.

Regele and Stark (2000) discussed impacts on aquatic 

resources resulting from CBNG effects on drainage 
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hydrology and water quality that would probably have 

the greatest likelihood of occurring under 

Alternative C. Potential impacts from reduced surface 

water availability would probably be limited to the 

unlikely event of a localized connection between a 

spring-fed stream and groundwater withdrawals. This 

could possibly result in the reduction or loss of springs 

and flowing reaches of stream channels that provide 

habitat for native flora and fauna in southeastern 

Montana. Regele and Stark (2000) cited studies by the 

MFWP that recognized the importance of perennial 

and intermittent prairie streams in the life history of 

native fishes, by providing spawning and rearing 

habitat for mainstem fish species. The effects of 

increased flows from CBNG discharges would include 

channel erosion, soils and vegetation loss, increased 

sediment load and sedimentation and degraded water 

quality; these effects would directly and indirectly 

impact fish, amphibians, aquatic invertebrates and

algae. Also, if great enough, increased TDS and 

salinity levels in streams receiving CBNG discharges

would affect fish and aquatic invertebrates, especially 

those species not well adapted to high TDS levels, 

such as salmonids found in higher-elevation streams. 

Regele and Stark (2000) cited studies that showed TDS 

concentrations should not be increased above 1,200 

micromhos if a water’s “excellent biological health 

characteristics are to be preserved.” The potential 

development of saline seeps down-gradient of CBNG 

holding ponds also would affect aquatic resources 

present in streams receiving these discharges. Regele 

and Stark (2000) cited the MFWP, which concluded 

that because of the limited fisheries habitat available in 

the arid environment of southeastern Montana, great 

care must be taken where there is a potential to 

degrade aquatic resources.

The Hydrological Resources impact analysis in this 

chapter estimated that 0.67 billion cubic feet of CBNG 

water would be discharged to the Montana portion of 

Powder River Basin drainages each year. This is 

equivalent to an additional, total year-round basin flow 

of 21 cfs and assumes a 70 percent conveyance loss 

prior to discharges reaching drainages. The 

Hydrological Resources impact analysis showed that 

resultant flow increases over base flows would average 

less than 1 percent in most of the Powder River Basin 

drainages. The largest percent base flow changes 

would occur in the Little Powder and Rosebud 

drainages, which are managed as non-trout, 

undesignated fisheries and have high or substantial 

fisheries resource values. Rosebud Creek has been 

proposed to be classified as a cold water fishery by the 

Northern Cheyenne Tribe. It supports northern pike 

and rainbow trout (FWS 1980). This additional volume 

of water in Powder River Basin drainages would not be 

expected to impact larger drainages or their water 

temperatures, but it would impact smaller perennial, 

intermittent and ephemeral drainages, especially if 

peak discharges of CBNG water to smaller drainages 

greatly exceed this annual average. Water quality 

would be impacted much more than water quantity 

from CBNG discharges because of the considerably 

higher TDS and constituent concentrations typically 

found in CBNG-produced water than in surface 

drainages. The Wildlife impact analysis in this chapter 

notes that the potential for impacting water quality by 

discharging CBNG production water with high salinity 

and sodicity would be greatest in smaller perennial and 

intermittent drainages during low-flow periods of the 

year. The effects of high TDS and constituent 

concentrations on aquatic organisms were discussed 

under Alternative A.

The temperature of the smaller perennial, intermittent

and ephemeral receiving water bodies may also be 

affected by the increased groundwater discharge 

associated with this alternative. The resultant 

temperature change and potential for affecting aquatic 

resources would depend on a number of variables that 

would have to be determined on a site-specific basis, 

such as volume and temperature of production and 

receiving water, time of year, species present and their 

thermal tolerances and life history considerations. In 

the event of reduced water temperatures in receiving 

waters, any resultant adverse effects would tend to be 

greater in those systems or portions of systems (for 

example, downstream reaches) dominated by species 

with warm water thermal preferences.

Surface discharges of CBNG-produced water would be 

subject to MDEQ MPDES Permit requirements and 

limitations for discharge into identified watersheds. 

The volume of CBNG production water potentially 

discharged to the Powder River Basin drainages in 

Montana that were listed in the Hydrological 

Resources impact analysis has a greater potential for 

causing sediment, flow and water quality-related 

impacts on aquatic resources than the effects of 

Alternatives A or B. However, these effects would be 

within the range of acceptable limitations stipulated 

under the various MPDES Permits that would have to 

be issued under Alternative C. For this alternative to be 

viable, conditions of the MPDES permits must be able 

to provide legally enforceable assurances that water 

quality, aquatic resources and the beneficial uses of 

receiving waters would not be degraded by production 

water discharges.

Special Status Species

The types of impacts and potential project effects on 

federally listed, candidate, significant concern, BLMsensitive and state species of concern under Alternative 

C would generally be similar to those described in the 
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preceding text for aquatic resources under this 

alternative. Special status species would potentially be 

affected by changes in the quantity and quality of 

receiving waters from discharges of CBNG-production 

water, construction of stream crossings, erosion 

generated by construction activities and effects of other 

activities discussed above for aquatic resources. Since 

production water would not be held in tanks or 

improved in quality, that which reaches the Tongue, 

Little Powder and Powder rivers would likely have 

increased SAR values that could affect the quantity 

and quality of receiving waters, especially during low 

or no flow conditions, as well as food sources for 

special status species. One special status species 

possibly present in downstream reaches of several of 

these drainages and found in the Yellowstone River

within the Powder River RMA that is potentially at 

risk is the federally-listed, endangered pallid sturgeon. 

Other special status species occupying similar habitat 

types in these particular waters also may be at risk. 

There also is the potential for affecting Montana Arctic 

grayling because of the nature of CBNG exploration 

and development activities that would occur under 

Alternative C. However, the likelihood of risk is 

probably low because grayling are generally found at 

relatively high, cold headwater locations within the 

Planning Area. Minimizing or avoiding activities in 

these specific types of areas to the extent possible 

would minimize the potential for affecting this species.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative C. CBNG 

development on the Crow Reservation is expected to 

comprise a portion of the estimated 7,200 CBNG 

production wells to be developed on tribal lands. To 

the extent that it does occur, potential impacts on 

aquatic resources would be similar to those described 

for private lands but would probably occur on a 

somewhat smaller scale than on BLM-administered or 

State lands. If there were in fact no CBNG 

development on tribal lands, then there are expected to 

be minimal impacts on aquatic resources on the 

reservation. Unlike Alternative B, there would be no 

restrictive buffer zone around the reservation under 

Alternative C.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described in general for 

Alternative C. CBNG development on the Northern 

Cheyenne Reservation is expected to comprise a 

portion of the estimated 7,200 CBNG production wells 

to be developed on tribal lands. To the extent that it 

does occur, impacts on aquatic resources would be 

similar to those described for private lands but would 

probably occur on a somewhat smaller scale than on 

BLM or State lands. Unlike Alternative B, there would 

be no restrictive buffer zone around the reservation 

under Alternative C.

Conclusions

The types of residual impacts that would persist for 

Alternative C are the same as described for Alternative 

A, but they would occur on a far greater scale. In 

addition, a large volume of CBNG-produced water 

would be discharged under Alternative C and there 

would be a potential for resultant residual impacts on 

aquatic habitat and organisms, including special status 

species, from that particular activity. One of the most 

noteworthy potential effects of this alternative on 

special status aquatic species would be possible risks 

to the endangered pallid sturgeon. 

There would be an increased risk for cumulative 

effects from CBNG activities associated with 

Alternative C, when compared to all the other 

alternatives, because of the substantial number of wells 

that would be developed. 

Unlike Alternative B, there would be no buffers around 

active coal mines or Indian reservations to minimize 

the potential for inter-related effects. 

Alternative D—Encourage Exploration and 

Development While Maintaining Existing 

Land Uses

Impacts on aquatic resources associated with 

Alternative D would include all of those CBNG-related 

impacts described for Alternatives A and/or B, but they 

would be greater in magnitude. The intensity and 

geographic extent of CBNG exploration, production

and abandonment and the acres of land disturbed in the 

short-term and long-term under Alternative D would 

be the same as described for Alternative B. However, 

Alternative D encourages CBNG development while 

maintaining existing land uses and protecting 

downstream water consumers. Alternative D, like 

Alternative B, contains the same set of mitigation

measures designed to avoid, minimize, or mitigate the 

impacts of CBNG development activities on aquatic 

resources. However, unlike Alternative B, CBNGproduced water (depending on water quality) would be 

treated, prior to its discharge or storage in holding

facilities, so that the effluent meets standards 

established by the MDEQ for downstream uses. 

Beneficial uses of produced water would be allowed 

and treatment would vary based on industrial, 

municipal, agricultural and wildlife uses. Treated, 

produced water would be discharged to drainages by 
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pipeline or constructed watercourses to avoid the 

potential for erosion and sediment-related impacts on 

aquatic resources. The treatment of produced water 

prior to its discharge to surface drainages through 

constructed facilities would greatly reduce the 

potential for elevated TDS, salinity and sodicity levels 

described for Alternative C. 

The Hydrological Resources impact analysis estimated 

that 2.24 billion cubic feet of CBNG water would enter 

the Montana portion of Powder River Basin drainages 

each year. This is equivalent to an additional, total 

year-round basin flow of 71 cfs and assumes no 

conveyance losses because of the use of pipelines or 

constructed water courses to convey discharges. The 

Hydrological Resources impact analysis showed that 

resultant flow increases over base flows would average 

1 percent in Powder River Basin drainages. The 

greatest increase in base flows (approximately by a 

factor of 4) would occur in the Little Powder and 

Rosebud drainages, which would impact aquatic 

habitat and organisms through the same mechanisms 

described under Alternative A. This volume of water 

would not be expected to impact larger drainages, but 

it would impact other smaller perennial, intermittent

and ephemeral drainages, especially if peak discharges 

of CBNG water to smaller drainages greatly exceed 

this annual average. There would also be a potential 

for adverse temperature-related effects on warm water 

fish species if there is a reduction in receiving water 

temperature in these smaller drainages. Otherwise, 

water quality of these streams would not be impacted 

by discharged water since it would have been treated. 

As noted for Alternatives A, B and C, conditions of the 

MPDES permits issued under Alternative D must be 

able to provide legally enforceable assurances that 

water quality, aquatic resources and the beneficial uses 

of receiving waters would not be degraded by 

production water discharges. 

Special Status Species

The types of impacts and potential project effects on 

special status species under Alternative D would 

generally be similar to those described in the preceding 

text for aquatic resources under this alternative. Many 

of these effects also would be similar to those 

described under Alternatives A and B, except they 

could be greater in magnitude because of the discharge 

of treated production water to drainages under 

Alternative D. Special status species potentially most 

vulnerable to project-related effects would include 

those in smaller perennial and intermittent drainages 

within the Powder River Basin. The overall likelihood 

of affecting special status species would probably be 

low or absent, depending on species distribution. 

However, as noted for the other alternatives, special 

status species may be somewhat more vulnerable than 

the more commonly-occurring aquatic species because 

of their limited distribution, low abundance and/or 

narrow habitat requirements.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative D. CBNG 

development on the Crow Reservation is expected to 

comprise a portion of the estimated 3,600 CBNG 

production wells to be developed on Crow tribal lands. 

To the extent that it does occur, potential impacts on 

aquatic resources would be similar to those described 

for private lands but would probably occur on a 

somewhat smaller scale than on BLM-administered or 

State lands. If there were no CBNG development on 

tribal lands, then there are expected to be minimal 

impacts on aquatic resources on the reservation. Until 

the tribe approves CBNG development on the 

reservation, a 2-mile wide buffer zone around the 

reservation would be enforced under Alternative D to 

minimize the potential for adjacent CBNG 

development to affect tribal aquatic resources.

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described in general for 

Alternative D. CBNG development on the Northern 

Cheyenne Reservation is expected to comprise a 

portion of the estimated 3,600 CBNG production wells 

to be developed on Northern Cheyenne Tribal lands. 

To the extent that it does occur, impacts on aquatic 

resources would be similar to those described for 

private lands but would probably occur on a somewhat 

smaller scale than on BLM-administered or State 

lands. If there were no CBNG development on tribal

Lands, then there are expected to be minimal impacts 

on aquatic resources on the reservation. Until the tribe

approves CBNG development on the reservation, a 2-

mile wide buffer zone around the reservation would be 

enforced under Alternative D to minimize the potential 

for adjacent CBNG development to affect tribal

aquatic resources.

Conclusions

The types of residual impacts that would persist for 

Alternative D are the same as described for 

Alternative A, with the following two exceptions. 

Impacts would occur on a far greater scale under 

Alternative D than Alternative A. Also, CBNG

production water discharged under Alternative D 

would be treated. Except for possible water 

temperature changes in smaller drainages, there would 

be no potential for residual water quality impacts on 
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aquatic resources, including special status species, 

from that particular activity. 

When compared to Alternative A, there would be an 

increased risk for cumulative effects from CBNG 

activities associated with Alternative D, but the effects 

would be less than Alternative C (based on the total 

number of wells developed). In addition, the 1-milewide buffer around active coal mines and the 2-milewide buffer around reservations under Alternative D 

would reduce the potential for cumulative inter-related 

impacts to occur. 

Alternative E—CBNG Exploration and 

Development with Enhanced Mitigation to 

Minimize Environmental Impacts While 

Maintaining Existing Land Uses

Impacts on aquatic resources associated with 

Alternative E would generally be comparable to the 

CBNG-related impacts described for Alternative B, 

which emphasizes the protection of natural and cultural 

resources. The number of CBNG wells developed 

would be the same as under Alternative B although 

more land would be disturbed under Alternative E in 

the short-term (99,000 acres) and the long-term 

(59,000 acres).The objective of Alternative E is to 

manage CBNG development in an environmentally 

sound manner while sustaining existing land uses. To 

meet this objective, Alternative E contains 

requirements designed to protect hydrologic resources 

by combining management options of CBNGproduced water so that no degradation of water quality, 

including thermal criteria, would be allowed in any 

watershed. These options include, but are not limited 

to, industrial, municipal, agricultural and wildlife 

beneficial uses, as well as injection, treatment, 

impoundment and discharge of CBNG water. CBNG 

operators would be required to develop a Water 

Management Plan as part of their overall Project Plan 

that describes how impacts on surface resources 

resulting from exploration and production activities 

would be minimized or mitigated and how a discharge 

(if proposed by the operator) could occur without 

damaging the watershed-in accordance with a required 

and approved MPDES Permit and MDEQ water 

quality laws. The Project Plan would be prepared in 

consultation with the affected Indian tribes, affected 

surface owners and other involved permitting agencies 

according to guidelines to be developed by the BLM 

and State of Montana. 

The lack of transportation corridor requirements under 

Alternative E would result in greater surface 

disturbances and possibly increased sediment delivery 

to nearby drainages compared to Alternative B. 

However, because of the overall beneficial effect of 

protective measures, including the mitigation measures

described earlier, relatively few impacts on aquatic 

resources would be expected under Alternative E. 

Aquatic resources in the same watersheds and 

drainages identified under Alternative B as being most 

sensitive to CBNG development also should be 

monitored closely during CBNG activities under 

Alternative E.

Special Status Species

The types of impacts and potential project effects on 

special status species under Alternative E would 

generally be similar to those described in the preceding 

text for aquatic resources under this alternative. 

Requirements designed to protect hydrologic resources 

by combining management options of CBNGproduced water so that no degradation of water quality 

would be allowed in any watershed would benefit 

special status species. The lack of transportation 

corridor requirements under this alternative would 

result in comparatively greater surface disturbances 

than under Alternative B and possibly increased 

sediment delivery to nearby drainages. However, 

because of the overall beneficial effect of protective 

measures, relatively few impacts on special status 

species would be expected under Alternative E. The 

same watersheds and drainages identified under 

Alternative B as being most sensitive to CBNG 

development also should be monitored closely during 

CBNG activities under Alternative E.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative E. CBNG 

development on the Crow Reservation is expected to 

comprise a portion of the estimated 3,600 CBNG 

production wells to be developed on Crow tribal lands. 

To the extent that it does occur, potential impacts on 

aquatic resources would be similar to those described 

for private lands but would probably occur on a 

somewhat smaller scale than on BLM or State lands. If 

there were no CBNG development on tribal lands, then 

there are expected to be minimal impacts on aquatic 

resources on the reservation. To determine potential 

impacts to the Crow Reservation from CBNG 

development on lands adjacent to the reservation, 

monitoring wells would be installed during the 

exploration phase on all BLM-administered oil and gas

estates that adjoin reservation boundaries in Montana. 

If monitoring indicates drawdown would occur on the 

reservation, mitigation such as the operator providing a 

hydrologic barrier, communitization agreement, or 

spacing that would protect Indian minerals from 

drainage, would be required.
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Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described in general for 

Alternative E. CBNG development on the Northern 

Cheyenne Reservation could reach as high as an 

estimated 3,600 CBNG production wells. To the extent 

that it does occur, potential impacts on aquatic 

resources would be similar to those described for 

private lands but would probably occur on a somewhat 

smaller scale than on BLM or State lands. If there were 

no CBNG development on tribal Lands, then there are 

expected to be minimal impacts on aquatic resources 

on the reservation. The same monitoring and 

mitigation procedures that were described for the Crow 

Reservation would be used on the Northern Cheyenne 

Reservation. 

Conclusions

The types of residual impacts that would persist for 

Alternative E are similar to those for Alternative B. 

These impacts would be essentially the same as 

described for Alternative A, except that impacts would 

occur on a greater scale.

When compared to Alternative A, there would be an 

increased risk for cumulative effects from CBNG 

activities associated with Alternative E, but the effects 

would be less than Alternative C. 

Alternative F—Phased Development 

Multiple Screens (High Range)

Impacts on aquatic resources associated with 

Alternative F (Phased Development) would generally 

be comparable to the CBNG-related impacts described 

for Alternatives B and E, which emphasize the 

protection of natural and cultural resources. The acres 

of land disturbed in the short term and long term under 

this alternative would be about the same as described 

for Alternative E. 

The objective of Alternative F is to manage CBNG 

development in a phased or sequential manner within 

4th Order watersheds, while maintaining limits on 

surface discharge of untreated produced water and 

surface area disturbances. To meet this objective, 

Alternative F is designed to protect hydrologic 

resources by establishing numerical limits on 

development rates within individual 4th Order 

watersheds while combining management options for 

CBNG-produced water to minimize water quality 

impacts. These produced water management options 

include, but are not limited to, industrial, municipal, 

agricultural and wildlife beneficial uses, as well as 

injection, treatment, impoundment and discharge of 

CBNG water. However, it is assumed that untreated 

CBNG discharge from state-permitted wells will 

exceed the limits established under Alternative F, so no 

untreated discharge is likely from BLM development 

under this alternative. For example, current discharge 

permits for untreated CBNG-produced water in the 

Tongue River drainage (including permits approved in 

2006) is approximately equal to the total allowable 

untreated discharge volume for the entire watershed 

under Alternative F (10 percent of 7Q10 flow) (see the 

Hydrological Resources section in Chapter 3). This 

limitation is established to minimize impacts on 

surface resources resulting from exploration and 

production activities while adhering to the required and 

approved MPDES Permit stipulations and MDEQ 

water quality laws.

The possibility that transportation corridors would not 

be utilized fully (subject to watershed-level analysis) 

under Alternative F coupled with the increased 

handling or processing requirements of production 

water, would result in greater surface disturbances and 

possibly increased sediment delivery to nearby 

drainages compared to Alternative B. However, 

because of the protective measures and the gradual 

development rate within each 4th Order watershed, 

relatively few impacts on aquatic resources would be 

expected under Alternative F. Aquatic resources in the 

same watersheds and drainages identified under 

Alternative B as being most sensitive to CBNG 

development also would be monitored closely during 

CBNG activities under Alternative F using an adaptive 

management approach.

The phased development and adaptive management 

aspects of Alternative F are likely to provide a 

substantial level of protection for aquatic resources. 

There is considerable uncertainty regarding the 

specific effects of CBNG development activities on 

aquatic resources because of limited data, unknown 

influences of other environmental factors (e.g., drought 

conditions and other land use activities) and the 

variability and uncertainty concerning baseline (predevelopment) conditions. Given these uncertainties, 

the systematic and gradual increases in CBNG 

development under Alternative F provide opportunities 

to monitor potential changes occurring in watersheds 

where CBNG development is occurring, as well as 

baseline conditions in watersheds scheduled for initial 

development activities. 

While all of the action alternatives would likely be 

implemented in a sequential manner, similar to 

Alternative F, they do not include specific schedules 

for overall development or development within 

specific watersheds. The scheduling uncertainties of 

the other alternatives decrease the likelihood of 

obtaining accurate and quantifiable data concerning 

potential changes in aquatic resources as a result of 
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CBNG development. For example, Alternative F 

establishes a sequential order of development for the 

various watersheds, which is expected to limit the 

variability of other environmental factors that can 

increase the uncertainty of monitoring results. 

The adaptive management process would use the 

information obtained from monitoring baseline 

conditions and conditions occurring during sequential 

CBNG development in a watershed to make 

appropriate adjustments to the extent or schedule for 

CBNG development in specific watersheds and the 

overall Planning Area. 

Special Status Species

The types of impacts and potential project effects on 

special status species under Alternative F would 

generally be similar to those described in the preceding 

text for aquatic resources under this alternative. 

Requirements designed to protect hydrologic resources 

by combining management options of CBNGproduced water to minimize water quality/quantity 

impacts in each watershed would protect special status 

aquatic species. The possibility that transportation 

corridors would not be utilized fully (subject to 

watershed-level analysis) under this alternative would 

result in comparatively greater surface disturbances 

than under Alternative B and possibly increased 

sediment delivery to nearby drainages. However, 

because of the protective measures, relatively few 

impacts on special status species would be expected 

under Alternative F. The same watersheds and 

drainages identified under Alternative B as being most 

sensitive to CBNG development also should be 

monitored closely during CBNG activities under 

Alternative F.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described in general for Alternative F. CBNG 

development on the Crow Reservation is expected to 

comprise a portion of the estimated 3,600 CBNG 

production wells to be developed on Crow Tribal 

lands. To the extent that it does occur, potential 

impacts on aquatic resources would be similar to those 

described for private lands but would probably occur 

on a somewhat smaller scale than on BLM or State 

lands. However, it is assumed that CBNG development 

would also occur in a similar incremental fashion for 

watersheds on the reservation to maintain economic 

viability of development activities. In addition, any 

developments on the Crow Reservation would be 

included in the total number of allowable wells (either 

annually or cumulatively) for each 4th Order 

watershed. If there were no CBNG development on or 

upstream of tribal lands, then there are expected to be 

minimal impacts on aquatic resources on the 

reservation. 

To determine potential impacts to the Crow 

Reservation from CBNG development within 5 miles 

of the reservation boundary in Montana, groundwater 

monitoring wells and analyses would be required to 

demonstrate the protection of Indian Trust Assets. If 

such protection could not be demonstrated, BLM 

would not approve the APD(s) in that area or would 

stop on-going development activities and shut in wells. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described in general for 

Alternative F. CBNG development on the Northern 

Cheyenne Reservation could reach as high as an 

estimated 3,600 CBNG production wells. To the extent 

that it does occur, potential impacts on aquatic 

resources would be similar to those described for 

private lands but would probably occur on a somewhat 

smaller scale than on BLM or State lands. If there were 

no CBNG development on tribal Lands, then there are 

expected to be minimal impacts on aquatic resources 

on the reservation. The same monitoring and 

mitigation procedures that were described for the Crow 

Reservation would be used on the Northern Cheyenne 

Reservation. 

Conclusions

The types of residual impacts that would persist for 

Alternative F are similar to those for Alternative B. 

These impacts would be essentially the same as 

described for Alternative A, except that impacts would 

occur on a far greater scale. However, the annual and 

cumulative watershed development limits would result 

in gradual environmental changes (if changes occur as 

a result of CBNG development) and the adaptive 

management approach would likely result in less

overall impacts than the other action alternatives. 

As some untreated production water could be 

discharged under Alternative F, there would be a 

potential for resultant residual impacts on aquatic 

resources, including special status species. However, 

such impacts would be limited by the constraints of the 

MPDES permit and the cumulative limit of untreated 

discharge from all CBNG developments within each 

4th Order watershed.

Cumulative effects from this activity would be similar 

to the effects described in Alternative A. However, an 

increased risk for cumulative effects would occur from 

CBNG activities associated with Alternative F, but 

would be less than Alternative C. 
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Alternative G—Phased Development 

Multiple Screens (Low Range)

Impacts on aquatic resources associated with 

Alternative G (Limited Phased Development) would 

be similar in nature to the CBNG-related impacts 

described for Alternative F, which emphasizes the 

same phased development approach. However, with 65 

percent fewer wells developed under Alternative G, the 

overall impacts to aquatic resources are expected to be 

substantially lower than all the other alternatives. 

The objective of Alternative G is the same as 

Alternative F, which is to manage CBNG development 

in a phased or sequential manner within 4th Order 

watersheds, while maintaining limits on surface 

discharge of untreated produced water and surface area 

disturbances. Thus, Alternative G is designed to 

protect hydrologic resources by establishing numerical 

limits on development rates within individual 4th

Order watersheds, while combining management 

options for CBNG-produced water to minimize water 

quality impacts. 

Like Alternative F, it is assumed that untreated CBNG 

discharge from state-permitted wells will exceed the 

limits established under Alternative G, so no untreated 

discharge is likely from BLM development under this 

alternative. 

Also similar to Alternative F, transportation corridors 

might not be utilized fully under Alternative G. In 

addition, the increased handling or processing 

requirements of production water, could result in 

greater surface disturbances and possibly increased 

sediment delivery to nearby drainages on an average 

(per well) basis, compared to the other alternatives. 

However, because of the adaptive management 

approach, the gradual development rate and the 

reduced overall development within each 4th Order 

watershed, relatively few impacts on aquatic resources 

would be expected under Alternative G. Aquatic 

resources in the most sensitive watersheds would also 

be monitored closely under the adaptive management 

approach.

While there is considerable uncertainty regarding the 

specific effects of CBNG development on aquatic 

resources, the phased development and adaptive 

management aspects of Alternative G (along with the 

overall reduced development) are likely to provide 

substantial protection for aquatic resources. 

While all of the action alternatives would also likely be 

implemented in a sequential manner, Alternatives F 

and G include specific schedules for overall 

development or development within specific 

watersheds. The scheduling increases the likelihood of 

obtaining accurate and quantifiable data concerning 

potential effects of CBNG development on aquatic 

resources because it facilitates adaptive management. 

The adaptive management process would use the 

information obtained during sequential CBNG 

development in a watershed to make appropriate 

adjustments to the extent or schedule of additional

CBNG development in that watershed or the overall 

Planning Area. 

Special Status Species

The types of impacts and potential project effects on 

special status species under Alternative G would be 

similar in nature to Alternative F, although the overall 

effects are expected to be less because 65 percent 

fewer CBNG wells would be developed within each 

4th Order watershed. The same watersheds and 

drainages identified under Alternative B as being most 

sensitive to CBNG development also should be 

monitored closely during CBNG activities under 

Alternative G. 

Crow Reservation

Impacts on the Crow Reservation would be similar to 

those described for Alternative F. As in Alternative F,

CBNG development on the Crow Reservation is 

expected to comprise a portion of the estimated 3,600

CBNG production wells to be developed on Crow 

Tribal lands. Any developments on the Crow 

Reservation would be included in the total number of 

allowable wells (either annually or cumulatively) for 

each 4th Order watershed. If there were no CBNG 

development on or upstream of tribal lands, then there 

are expected to be minimal impacts on aquatic 

resources on the reservation. 

To determine potential impacts to the Crow 

Reservation from CBNG development within 5 miles 

of the reservation boundary in Montana, groundwater 

monitoring wells and analyses would be required to 

demonstrate the protection of Indian Trust Assets. If 

such protection could not be demonstrated, BLM 

would not approve the APD(s) in that area or would 

stop on-going development activities and shut in wells. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described for the Crow Reservation. 

Total CBNG development on the Northern Cheyenne 

Reservation could reach as high as an estimated 3,600 

CBNG production wells. The same monitoring and 

mitigation procedures that were described for the Crow 

Reservation would be used on the Northern Cheyenne 

Reservation. 
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Conclusions

The types of residual impacts that would persist for 

Alternative G are similar to those for Alternative F, 

except that impacts would occur on a smaller scale, 

due to the restricted overall development. Also, the 

annual and cumulative watershed development limits 

would result in gradual environmental changes (if 

changes occur as a result of CBNG development) and

the adaptive management approach would likely result 

in less overall impacts than the other action 

alternatives. 

As some untreated production water could be 

discharged under Alternative G, there would be a 

potential for resultant residual impacts on aquatic 

resources, including special status species. However, 

such impacts would be limited by the constraints of the 

MPDES permit and the cumulative limit of untreated 

discharge from all CBNG developments within each 

4th Order watershed. Cumulative effects from this 

activity would be similar to the effects described in 

Alternative F, but less extensive.

Alternative H—Preferred Alternative - 

Multiple Screens

For aquatic resources, restrictions on CBNG 

development would likely be similar to Alternative F, 

as both alternatives assume a similar extent of CBNG 

development. While Alternative F uses restrictions on 

the overall and geographic extent of CBNG 

development to protect aquatic resources, Alternative 

H relies on specific screening criteria. Of the four 

screening criteria, the water resources criteria 

principally relates to aquatic resources. Thus, 

alternatives F and H provide mechanisms for 

controlling the cumulative effects of CBNG 

development within the CBNG project area, using an 

adaptive management approach. However, Alternative 

H would minimize the potential effects of CBNG 

development on aquatic resources by also relying on 

actual water quality monitoring data, rather than just 

limiting or gradually increasing CBNG development. 

Although monitoring and the actual rate of CBNG 

development would likely be similar for both of these 

alternatives, Alternative H uses specific monitoring 

criteria to facilitate the adaptive management decisionmaking process. However, because of the similarities 

between these two alternatives, their overall effects on 

aquatic resources would likely be similar. The type and 

magnitude of such effects are summarized below. 

Unlike Alternative F, where it is assumed that 

untreated CBNG discharge from state-permitted wells 

would exceed the MPDES discharge limits and allow 

no additional untreated BLM discharges, Alternative H 

could result in additional BLM discharges so long as 

water quality criteria are not exceeded. This approach 

places more emphasis on specific water quality 

criteria, rather than relying on total discharge 

limitations to protect aquatic habitat. The water quality 

criteria under Alternative H would also encompass 

potential indirect effects of off-line reservoirs or 

surface applications of produced water on aquatic 

resources. 

In addition to applying the water resources screening 

process, Alternative H would require operators to 

prepare Project PODs for well densities greater than 1 

per 640 acres. This is expected to control the rate of 

CBNG development in specific geographic regions and

provide a process for adaptive management review. 

While there is still considerable uncertainty regarding 

the specific effects of CBNG development on aquatic 

resources, the adaptive management and water quality 

monitoring aspects of Alternative H are likely to 

provide additional protection for aquatic resources 

compared to other alternatives. 

While all of the action alternatives would likely be 

implemented in a sequential manner, Alternatives F, G

and H include specific adaptive management criteria to 

control overall development, development rate, or 

development within specific watersheds. The 

scheduling and/or monitoring components increase the 

likelihood of obtaining accurate and quantifiable data 

concerning potential effects of CBNG development on 

aquatic resources, thereby facilitating the adaptive 

management process. This process would use the 

information obtained during sequential CBNG 

development in a watershed, or overall Planning Area, 

to make appropriate adjustments to the extent or 

schedule of additional CBNG development. As a 

result, few impacts on aquatic resources are expected 

under Alternative H, however, this alternative is 

expected to have more impacts on aquatic resources 

than Alternatives B and G. 

The construction and use of CBNG-related facilities 

(i.e., roads, pipelines and utility corridors) can also 

cause direct and indirect effects to aquatic resources. 

The primary effects include direct loss of habitat (e.g., 

road crossing culverts), effects on water quantity and 

quality from changes in runoff characteristics and

migration barriers or habitat fragmentation. The effects 

of these development-related facilities under 

Alternative H would be similar to Alternative F, as 

both alternatives have provisions to limit such 

facilities. However, the specific water quality 

monitoring requirements of Alternative H are expected 

to incorporate these potential additional effects on 

aquatic resources.
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Special Status Species

The types of impacts and potential project effects on 

special status species under Alternative H would be 

similar to Alternative F, as both alternatives assume a 

similar extent of CBNG development and both include 

measures to control the rate of development. The same 

watersheds and drainages identified under Alternative 

B as being most sensitive to CBNG development also 

should be monitored closely during CBNG activities 

under Alternative H.

Crow Reservation

Impacts on the Crow Reservation would be similar to 

alternatives F and G, as CBNG development within 5 

miles of the reservation boundary in Montana would 

require groundwater monitoring wells and analyses to 

demonstrate the protection of Indian Trust Assets. In 

addition, the maximum extent of CBNG development 

on the Crow Reservation would be the same for all 

these alternatives. If no CBNG development occurs on 

or upstream of tribal lands, minimal impacts to 

reservation aquatic resources are expected. 

Northern Cheyenne Reservation

Impacts on the Northern Cheyenne Reservation would 

be similar to those described for the Crow Reservation. 

Total CBNG development on the Northern Cheyenne 

Reservation could reach as high as an estimated 3,600 

CBNG production wells. The same monitoring and 

mitigation procedures that were described for the Crow 

Reservation would be used on the Northern Cheyenne 

Reservation. 

Conclusions

The types of residual impacts that would persist for 

Alternative H are similar to those for Alternative F. 

Although Alternative H has no specific annual or

cumulative watershed development limits, CBNG 

development is expected to be about the same as 

Alternative F. This is expected to result in gradual 

environmental changes (if changes occur as a result of 

CBNG development) and the monitoring and adaptive 

management aspects would likely result in less overall 

impacts than the other full-field development

alternatives. 

As some untreated production water could be 

discharged under Alternative H, there would be a 

potential for greater residual impacts on aquatic 

resources, including special status species. However, 

such impacts would be limited by the constraints of the 

MPDES permit and water quality monitoring 

requirements. Cumulative effects from this activity 

would also be similar to the effects described in 

Alternative F.