HYDROLOGY APPENDIX

HYDROLOGY APPENDIX

Summary of Water Resources Technical Report

HYD-1

Summary of Water 

Resources Technical 

Report

Introduction

During the second half of the 1990s, coal bed 

methane (CBNG) production increased dramatically 

nationwide to represent a significant new source of 

natural gas to meet ever-growing energy demands. In 

Montana, oil & gas development has been growing 

since the first oil wells were drilled in the early 20th

century. There are currently more than 200 

commercially producing CBNG wells in the state of 

Montana, all of which are located in the Powder 

River Basin near the town of Decker, Montana. 

CBNG development in the Montana portion of the 

Powder River Basin (PRB) is in part a result of 

successful development in the Wyoming portion of 

the basin where CBNG activity started as early as 

1993 (Flores et al. 2001).

A primary intent of the Montana CBNG

Environmental Impact Statement (EIS) is to provide 

an overall projection of impacts associated with 

CBNG development for the planning areas and to 

address issues raised as part of the public scoping

process. Of primary consideration for the EIS are 

water resources. Due to the extraction methods 

required for CBNG production, impacts to surface 

water and groundwater can potentially result from 

CBNG development. The purpose of the Water 

Resources Technical Report (WRTR) (ALL 2001b) 

is to serve as one of many supporting documents for 

the subject EIS. Following is a short summary of the 

WRTR.

Study Area

The planning area for the EIS is defined as the area 

where oil and gas decisions will be made by the BLM

and the State of Montana. The BLM’s planning area 

is the oil and gas estate administered by the BLM in 

the Powder River and Billings Resource Management 

Planning (RMP) areas. The State of Montana’s 

planning area is statewide, with emphasis on the 

state-administered oil and gas within the BLM 

planning area and in Blaine, Park and Gallatin 

counties. The planning area excludes those lands 

administered by other agencies (for example, Forest 

Service and Tribal Councils). For ease of reference, 

the Billings and Powder River RMP areas, and 

Blaine, Park, and Gallatin counties, are referred to in 

the document as the BLM and State “CBNG

emphasis area.” This is the 16-county area within the 

BLM and state planning area where CBNG

development interest has been identified.

CBNG Production Operations

During CBNG production, water is pumped up a 

tubing string to be put into a water flow-line for 

handling or discharge. At the only producing CBNG

field in the Montana portion of the PRB, the water is 

either used in drilling new wells, pumped into ponds 

for use by the land owner, or discharged to the 

Tongue River through a MDEQ discharge permit. 

Assessment of management alternatives requires an 

accurate estimate of the amount of produced water to 

be produced from each well. CBNG wells must pump 

water from the reservoir to lower pressure within the 

coal, to augment the formation of cleat, and to allow 

the natural gas to break out as a discrete phase. The 

amount of water that must be pumped off appears to 

vary not only from reservoir to reservoir, but also 

during the history of each individual producing well 

according to the specific coal bed reservoir it is 

producing from, and its proximity to other producing 

wells. The WRTR compiles average water production 

rates for approximately 200 wells in the CX field 

normalized to the age of each well (MBOGC oil and 

gas database). This data was prepared by averaging 

the water production rates from active CBNG wells 

during each month dating from the date of first 

production. The exponential trend line is extrapolated 

from this data is: Q = 14.661e-0.0242t When Q is 

discharge per well in gallons per minute (gpm), and t 

is time in months. This indicates that initial 

discharges are approximately 15 gpm per well, and 

the 20-year average discharge would be 2.5 gpm. It 

should be noted that although the average initial 

discharge is approximately 15 gpm, some wells have 

discharges as high as 20-25 gpm.

Regional Geology

The planning area of the EIS centers on the Powder 

River RMP area and the Billings RMP area. The 

planning area contains three major basinal features –

Powder River, Big Horn, and Bull Mountains – and 

surrounding uplifted areas. The asymmetric basins 

are the result of sedimentary deposition and structural 

subsidence with most of the fill consisting of the Fort 

Union Formation. The Fort Union Formation also 

contains most of the coals occurring in these three 

basins. 
HYDROLOGY APPENDIX

Summary of Water Resources Technical Report

HYD-2

Fort Union Formation

The Fort Union Formation encloses the various coal 

seams within the Montana portion of the PRB; these 

coals function as the source and reservoir for the 

CBNG, as well as aquifers carrying groundwater of 

varying quantity and quality. Depth to coal seams in 

the Montana portion of the PRB range from exposure 

at ground surface to 1,000 feet or more below land 

surface. Coal thickness varies from thin stringers to 

over 50 feet and can form aggregate thicknesses that 

exceed 100 feet. Coal seams in the Fort Union do not 

have significant matrix porosity and permeability; 

they can act as aquifers because fluids such as water 

and methane are contained within the coal’s fracture 

system, known as cleat. The fractures accumulate the 

fluids and allow the fluids to move horizontally and 

vertically.

Quaternary Alluvium 

Quaternary age sediments are those that are 

Pleistocene (the latest glacial episode) and Recent 

(post-glacial episode) in age; the sequence is 

dominated by events and effects associated with 

continental glaciation, including glacial till and 

exaggerated peri-glacial valley fill. Quaternary 

sediments in the PRB and most of the state are 

present as variable fill in stream and river valleys. 

Quaternary Alluvium consists of unconsolidated 

sand, silt, and gravel that make up the floodplains and 

stream terraces of creek valleys in the PRB. Alluvium 

aquifers are largely unconfined and connected to 

active river flow. Because alluvial aquifers can 

deliver large quantities of water-to-water supply 

wells, they are important stratigraphic features. 

Alluvial aquifers can be impacted by surface activity 

and can act as a conduit to carry those impacts to 

valuable surface water resources. 

Hydrology

Hydrology identifies aquifers (porous units 

containing water) and aquitards (non-porous strata 

that serve to confine and separate aquifers) in a 

geographic and vertical sense. Aquifers can contain 

drinkable water, brackish water of limited usability, 

or salt water. In the EIS planning area, several 

formations contain drinking water but show variable 

reservoir quality and water quality. The Montana 

portion of the PRB includes many aquifers that 

represent different hydrologic flow regimes. The 

basin includes unconfined aquifers as well as 

confined, bedrock aquifers. Aquifers range from the 

unconfined Quaternary alluvium in the streambeds of 

rivers and creeks to the Mississippian Age Madison 

Formation in excess of 10,000 feet below the surface. 

The water quality within these aquifers ranges from 

less than 300 mg/L TDS to more than 30,000 mg/L 

TDS. The aquifers also vary in depth from the basin 

center to the margin. Coal aquifers are widespread, 

supply large numbers of water wells, and will be 

impacted most by CBNG production. Alluvial 

aquifers are commonly unconfined and in direct 

contact with surface water and can, therefore, be 

impacted by surface discharge of CBNG water.

Watersheds

Watersheds are important to predicting the impacts 

from CBNG development in Montana. Water 

resource factors such as water quality, water use, and 

potential impacts are discussed throughout the report 

in terms of watersheds. Each watershed is drained by 

a single stream or river and each is bounded by a noflow topographic boundary. Streams and rivers are 

profoundly influenced by their watersheds; in 

particular water volume and water quality vary from 

base flow conditions to high-flow conditions under 

the control of runoff from land surfaces and recharge 

to rivers by aquifers. The WRTR highlights the 

watersheds in the PRB along with potential CBNG

areas. 

Groundwater Quality

Quality of groundwater resources are detailed in the 

WRTR. The report lists quality statistics for the 

major aquifers from various parts of the CBNG

emphasis area with emphasis on the coal seam 

aquifers. 

Water Resources Impact Issues

Groundwater Drawdown from CBNG

Development

Groundwater drawdown from CBNG production has 

been documented inside and adjacent to existing 

production in Montana. CBNG production in the 

PRB requires drawdown of coal aquifers within the 

producing field in order to liberate methane. Water 

wells and springs to but outside of a producing 

CBNG field may also be impacted. Drawdown can be 

documented by way of dedicated monitoring wells or 

by gauging private water wells. In Montana’s CX 

Ranch CBNG field, the MBMG has installed 

monitoring wells designed to track drawdown due to 

the coal mines in the area as well as CBNG

development.
HYDROLOGY APPENDIX

Summary of Water Resources Technical Report

HYD-3

Surface Water Impact from 

Discharge

Impacts to surface water from discharge of CBNG

water can be severe depending upon the quality of the 

CBNG water. Some watersheds may be able to 

absorb the discharged water while others are sensitive 

to large amounts of low-quality CBNG water. 

Surface water quality in the watersheds is tabulated 

in the WRTR. Water quality data is from stream 

gauging points maintained by the USGS; these multiyear collections of water quality data illustrate 

changes within the stream from times of high run-off 

(typically June for the PRB) when the river is the 

highest and water is mostly the result of precipitation 

from spring rains and melting snow. During periods 

of high flow the streams and rivers contain higher 

quality water. The USGS data also contains data on 

base-flow conditions (typically winter in the PRB) 

when streams are at their lowest flow and water 

quality is the lowest since much of the water is 

recharge from alluvial and bedrock aquifers where 

groundwater is often of low quality. Discharge 

scenarios are described and resultant water quality is 

computed on a watershed basis.

Mitigation

CBNG production in the Montana PRB will certainly 

impact groundwater. Impacts to groundwater 

resources may however be mitigated through the use 

of water well agreements, limits placed on discharge 

and monitoring programs. Furthermore, a predictive 

model may be helpful as an approximation of future 

impacts. Groundwater rights will be protected 

through the use of spring/water well mitigation 

agreements and an approved monitoring plan to aid 

in the identification of potentially significant 

drawdown impacts. Surface water resources can be 

protected by limiting discharge through alternative 

management techniques. 

Conclusions and Attachments

The WRTR concludes with a list of key water 

resource factors that are important to the subject of 

impacts. The appendices contain several pertinent 

documents as well as groundwater drawdown data 

from monitoring wells in the vicinity of the CX 

Ranch field, decline analysis from the CX Ranch 

field, and groundwater quality data from coal seam 

aquifers. 
HYDROLOGY APPENDIX

TMDL Schedule

HYD-4

TMDL Schedule for CBNG

Emphasis Area of Montana

Section 303 (d) of the Federal Clean Water Act and 

Sections 75-5-701 MCA, et. seq

On June 21, 2000, the United States District Court of 

Montana ordered EPA to work with the State of 

Montana to develop and adopt a schedule that would 

result in developing all necessary TMDLs for waters

on Montana’s 1996 Section 303(d) list (EIS Table 3-

6) by May 5, 2007. On November 1, 2000, MDEQ 

and EPA published a schedule that was based upon a 

watershed or planning area approach. MDEQ divided 

the state into 91 TMDL Planning Areas each with a 

deadline for completing all necessary TMDLs. Since 

that time, an agreement has been reached to extend 

these timelines such that all TMDLs will be 

completed prior to May 5, 2012 (Yashan, pers. com., 

12/8/05). This revised schedule is shown graphically 

on Figure HYD-1. The surface waters most likely to 

be affected by CBNG development are located in the 

Tongue Powder and Rosebud TMDL Planning Areas. 

The TMDL analyses for these areas are currently 

underway.

. of the Montana 

Water Quality Act requires Montana to develop 

“Total Maximum Daily Loads” (TMDLs) for lakes, 

rivers, and streams that are not meeting water quality 

standards. A TMDL is the amount of a pollutant that 

a waterbody can assimilate from point, non-point and 

natural sources and still meet water quality standards. 

In short, TMDLs guide the development of discharge 

targets for contributing sources that once 

implemented will restore or protect water quality.

All waters in Montana have been assigned to one of 

nine classifications based upon their presumed ability 

to support certain beneficial uses (i.e. drinking water, 

recreation, fisheries and aquatic life, agriculture, and 

industrial uses). Each classification has specific water 

quality standards including numerical and narrative 

limits. Waters that fail to meet the numerical or 

narrative standards are considered impaired. Montana 

must develop one or more TMDLs for each impaired 

waterbody. 

In accordance with Section 303(d) of the Federal 

Clean Water Act, the Montana Department of 

Environmental Quality (MDEQ) has prepared a list 

of impaired and threatened waters every two years 

since 1992. This so called “303(d) list” identifies 

lakes, rivers and streams that are not meeting water 

quality standards and establishes priorities for TMDL 

development. However, Montana like the rest of the 

nation was slow to develop TMDLs. 

Independent of the court order, but as required by the 

Federal Clean Water Act and the Montana Water 

Quality Act, MDEQ prepared a 303(d) list in 2004. 

The 2004 list was finalized with EPA approval on 

November 24, 2004. It is superior to earlier lists for 

several reasons. First, significantly more data was 

available for making listing decisions. Second, the 

public review process was substantially expanded 

including a lengthy comment period and public 

meetings around the state. Third, MDEQ 

significantly improved the methods for making 

listing decisions. Fourth, MDEQ dramatically 

improved the supporting documentation for all listing 

decisions and made the information easily accessible 

by the public.

Although the court order mandates the 1996 list (EIS 

Table 3-6) as the starting point, both the 1996 and the 

2004 lists should be consulted when making TMDL 

decisions. Figures HYD-2 to HYD-4 provides a 

summary of the waters in the Tongue, and Rosebud 

Creek basins that are on the 2004 list. No segments of 

the Powder River are on the 2004 list. The 

accompanying tables (Tables HYD-1 to HYD-3) 

identify the pollutants of concern and summarize the 

reasons for the listings.

The MDEQ or EPA is required to develop all 

necessary TMDLs for each waterbody and pollutant 

identified as impaired or threatened on the 1996 list. 

A TMDL may not be necessary for a waterbody 

listed on the 1996 list for a couple of reasons. First, a 

TMDL is unnecessary if further assessment, such as 

was done for the 2004 list, determines that the 

waterbody is meeting water quality standards for the 

particular pollutant. During the development of the 

2000, 2002, and 2004 lists, MDEQ determined that 

several waters in the Tongue, Powder, and Little 

Powder river basins that were listed as impaired on 

the 1996 list, were actually meeting water quality 

standards (i.e., Mizpah Creek was found to be fully 

supporting for nutrients, dissolved oxygen, inorganics 

and suspended solids). Second, EPA has determined 

that TMDLs are not necessary for “pollution” that is 

not associated with a specific pollutant (i.e., flow or 

habitat alteration). EPA described their position on 

this issue to MDEQ in a July 23, 2001 letter 

concerning a flow alteration TMDL for Big Creek, a 

tributary of the Upper Yellowstone River. It should 

be noted however, that further assessment frequently 

shows that flow or habitat alterations cause high 

levels of pollutants (i.e., flow and habitat alteration 

can cause violations of temperature standards). 
HYD-5

Figure HYD-1:

A graphical display of MDEQ's TMDL Planning Schedule (obtained from P. Schade (MDEQ) 
HYDROLOGY APPENDIX

TMDL Schedule

HYD-6

Figure HYD-2: Impaired Waterbodies in the Upper Tongue Watershed

Figure HYD-3: Impaired Waterbodies in the Lower Tongue River Watershed
HYDROLOGY APPENDIX

TMDL Schedule

HYD-7

Figure HYD-4: Impaired Waterbodies in the Rosebud Creek Watershed

Table HYD-1: List of Impaired Waterbodies in the Upper Tongue River Watershed

Hydrologic Unit Code 10090101 Watershed UPPER TONGUE

ID Segment ID Waterbody 

Segment

List 

Categor

y

Size

Use 

Clas

s

Use Support Probable Causes 

of Impairment

Probable 

Sources of 

Impairment Aqu

a 

Cold 

Fish

War

m 

Drin

k 

Swi

m 

A

gr

In

d

1 MT42B002_0

31

Hanging Women 

Creek from Stroud 

Cr. To the mouth 

(Tongue R.)

5 18.5 

M C-3 P P X Siltation

Grazing related 

sources

Agriculture

2

MT42B003_0

10

Tongue River 

Reservoir 5

3500 

A B-2 P X X P F F

Algal 

Growth/Chlorophyll 

a

Domestic 

wastewater 

lagoon

Agriculture
HYDROLOGY APPENDIX

TMDL Schedule

HYD-8

Table HYD-2: List of Impaired Waterbodies in the Lower Tongue River Watershed

Hydrologic Unit Code 10090102 Watershed LOWER TONGUE

ID Segment ID Waterbody 

Segment

List 

Categor

y

Size

Use 

Clas

s

Use Support Probable 

Causes of 

Impairment

Probable 

Sources of 

Impairment Aqu

a 

Cold 

Fish

War

m 

Drin

k 

Swi

m 

A

gr

In

d

1 MT42C001_0

11

TONGUE RIVER 

from diversion dam 

just above Pumpkin 

Cr. To the mouth 

(Yellowstone R.)

4C 20.4 

M B-3 P P X P F F Flow alteration

Dam 

Construction

Flow Regulation/ 

Modification

Hydromodificatio

Table HYD-3: List of Impaired Waterbodies in the Rosebud Creek Watershed

Hydrologic Unit Code 10100003 Watershed ROSEBUD

ID Segment ID Waterbody 

Segment

List 

Categor

y

Size

Use 

Clas

s

Use Support Probable 

Causes of

Impairment

Probable 

Sources of 

Impairment Aqu

a 

Cold 

Fish

War

m 

Drin

k 

Swi

m 

A

gr

In

d

1 MT42A001_0

11

ROSEBUD CREEK, 

From the mouth 3.8 

mi upstream to an 

irrigation dam

4C 3.8 M C-3 P P X

Bank erosion

Other habitat 

alterations

Removal of 

Riparian 

Vegetation

Habitat 

Modification 

(other than 

2

MT42A001_0

12

ROSEBUD CREEK, 

Northern Cheyenne 

Res. Boundary to an 

irrigation dam 3.8 mi 

above the mouth 5

105.8 

M C-3 X P X

Other

Nutrients

Dam 

Construction

Hydromodificatio

n

Although, during the preparation of the 2000, 2002, 

and 2004 lists the MDEQ determined that several 

waterbodies on the 1996 list were meeting the water 

quality standards for some of the listed pollutants, it 

was far more common for MDEQ to determine that

there was insufficient credible data to make a listing 

decision. MDEQ determined that many segments of 

the Tongue and Powder rivers and some tributaries 

lacked sufficient credible data to determine whether 

the waters are impaired, threatened, or fully 

supporting the numerical and narrative water quality 

standards. These waters require additional assessment 

prior to developing TMDLs for the associated TMDL 

Planning Areas. The reassessment work has been 

conducted, and MDEQ is in the process of evaluating 

that data. It is possible that MDEQ will determine 

that additional waterbodies are meeting the standards 

for listed pollutants. If so, a TMDL will not be 

necessary, even though the waterbody and the 

pollutant were listed on the 1996 list. Conversely, 

additional TMDLs may be necessary if the 

assessment demonstrates that a waterbody is 

impaired for other pollutants that were not originally 

identified on the 1996 list.

The 1996 list identified many waters within the 

Tongue and Powder TMDL planning areas as 

impaired by salinity, total dissolved solids, chlorides, 

metals, inorganics, suspended solids, siltation, 

nutrients, low dissolved oxygen, pathogens, flow 

alteration, thermal modification, and habitat 

alteration. Of these pollutants, salinity, total dissolved 

solids, metals, and nutrients are frequently associated 

with produced water from CBNG development.

Additionally, it should be noted that pollutants 

including salinity, total dissolved solids, and nutrients 

are also frequently associated with agricultural 

operations. CBNG development may also cause flow 

alterations and associated pollutants to exceed 

standards (i.e., total suspended solids). 
HYDROLOGY APPENDIX

TMDL Schedule

HYD-9

As mentioned earlier, the court order prohibits 

MDEQ from issuing any new MPDES permits or 

renewals that would increase permitted discharges 

until all necessary TMDLs are established for a 

particular impaired waterbody. This provision of the 

court order has a direct bearing on CBNG

development. Unless producers choose a no 

discharge option, such as reinjection, MPDES 

permits will be required for CBNG development. 

MDEQ and EPA are applying the court order on a 

pollutant-specific basis. For example, if the water is 

listed for nutrients and the new source will not 

discharge nutrients, a permit can be issued. Likewise, 

a permit can be renewed, if an existing source intends 

to increase its discharge but the effluent limit for 

nutrients will remain the same. Under some 

circumstances a permit can be issued even when the 

new discharge contains the pollutant of concern. By 

regulation, such permits must contain water quality 

based effluent limits that insure that the water quality 

standards will be met downstream of the discharge. 

For example, if the water quality standard is 

expressed as an in-stream concentration and the 

concentration in the discharge is less than the 

standard, the new source may actually improve water 

quality. 

MDEQ is prohibited from issuing permits for 

discharges that would cause exceedances of a state 

water quality standard (i.e., where there is no 

assimilative capacity). This will be the case for many 

impaired waterbodies. Therefore, MDEQ will 

frequently not be able to issue a permit until a TMDL 

is developed for the entire watershed. A watershed 

TMDL will identify the major point and non-point 

sources contributing to the impairment and establish 

discharge targets for the pollutant of concern. In 

combination, the limits for all the sources must insure 

that water quality will improve to the point where the 

standards are met. The Montana Water Quality Act 

requires MDEQ to work with local landowners to 

implement voluntary measures (reasonable land soil 

and water conservation practices) to reduce pollutant 

loads from non-point sources. The Act also requires 

targets for point sources to be incorporated into

MPDES permits in the form of effluent limits. The

changes would normally be made during the next 

scheduled permit renewal and could include permits 

issued between now and the final development of the 

watershed TMDL. A watershed TMDL may include 

an allocation for growth to allow for new or increased 

discharges in the future and facilitate permitting. To 

provide for growth existing point and non-point 

sources would need to reduce their discharges even 

further. 

Developing a TMDL takes time and involves 

completing the ongoing assessments; coordinating 

with landowners and CBNG producers in Montana, 

on tribal lands, and perhaps in Wyoming; assigning 

allocations for point and non-point sources; drafting 

the TMDL and a technical support document; 

conducting public meetings; and obtaining EPA 

approval. 
HYDROLOGY APPENDIX

EC and SAR Standards

HYD-10

Specific Electrical Conductivity (EC as uS/cm) and Sodium Adsorption Ratio 

(SAR) Limits for the Tongue, Powder, and Little Powder River Basins and 

Rosebud Creek

MONTANA DEQ NUMERIC STANDARDS FOR ELECTRICAL CONDUCTIVITY

(EC) AND SODIUM ADSORPTION RATIO (SAR). ARM 17.30.670 (2003 Version)

(1) No person may violate the numeric water quality standards or the 

criteria for determining nonsignificant changes in water quality 

identified in (2) through (6). Compliance with the standards and 

criteria contained in (2) through (6) will be determined according to 

the procedures specified in (7).

(2) The numeric standards for electrical conductivity (EC) and sodium 

adsorption ratio (SAR) for the mainstems of Rosebud Creek, the Tongue, 

Powder, and Little Powder rivers from November 1 through March 1 are as 

follows:

(a) for Rosebud Creek and the Tongue River, the monthly average 

numeric water quality standard for EC is 1500 μS/cm and no sample 

may exceed an EC value of 2500 μS/cm. The monthly average numeric 

water quality standard for SAR is 5.0 and no sample may exceed an 

SAR value of 7.5; and

(b) for the Powder River and the Little Powder River, the monthly 

average numeric water quality standard for EC is 2500 μS/cm and no

sample may exceed an EC value of 2500 μS/cm. The monthly average 

numeric water quality standard for SAR is 6.5 and no sample may 

exceed an SAR value of 9.75.

(3) The numeric standards for EC and SAR for the mainstems

of Rosebud Creek, the Tongue, Powder, and Little Powder rivers from 

March 2 through October 31 are as follows:

(a) for Rosebud Creek and the Tongue River, the monthly average 

numeric water quality standard for EC is 1000 μS/cm and no sample 

may exceed an EC value of 1500 μS/cm. The monthly average numeric 

water quality standard for SAR is 3.0 and no sample may exceed an 

SAR value of 4.5; and

(b) for the Powder River and Little Powder River, the

monthly average numeric water quality standard for EC is 2000 

μS/cm and no sample may exceed an EC value of 2500 μS/cm. The 

monthly average numeric water quality standard for SAR is 5.0 and 

no sample may exceed an SAR value of 7.5.

(4) For all tributaries and other surface waters in the Rosebud Creek, 

Tongue, Powder, and Little Powder River watersheds, the monthly average 

numeric water quality standard for EC is 500 μS/cm and no sample may 

exceed an EC value of 500 μS/cm. The monthly average numeric water 

quality standard for SAR from March 2 through October 31 is 3.0 and no 

sample may exceed an SAR value of 4.5. The monthly average numeric water

quality standard for SAR from November 1 through March 1 is 5.0 and no 

sample may exceed an SAR value of 7.5.

(5) For the Tongue River Reservoir, the monthly average numeric water 

quality standard for EC is 1000 μS/cm and no sample may exceed an EC 

value of 1500 μS/cm. The monthly average numeric water quality standard 

for SAR is 3.0 and no sample may exceed an SAR value of 4.5.

(6) Changes in existing surface or ground water quality with respect to 

EC and SAR are nonsignificant according to the criteria in 75-5-

301(5)(c), MCA, provided that the change will not have a measurable 
HYDROLOGY APPENDIX

EC and SAR Standards

HYD-11

effect on any existing or anticipated use or cause measurable changes in

aquatic life or ecological integrity.

(7) For purposes of determining compliance with the water quality 

standards and nonsignificance criteria for all parameters of concern in 

any new or increased discharge of unaltered ground water from coal bed 

methane development, the department shall determine effluent or 

compliance limits (e.g., evaluate the design of disposal systems) by 

using a flow-based analysis that considers a range of flows or monthly 

flow probability. With respect to EC and SAR, the department shall also 

use the median chemistry for the specified flow range or monthly flow.

(8) If any of the provisions of (6) or (7), or both of them, are 

declared to be invalid, then the numeric water quality standards and 

requirements specified in (1) through (7) shall be void. (History: 75-5-

301, 75-5-303, MCA; IMP, 75-5-301, 75-5-303, MCA; NEW, 2003 MAR p. 779, 

Eff. 4/25/03.)

17.30.670 NUMERIC STANDARDS FOR ELECTRICAL CONDUCTIVITY (EC) AND SODIUM 

ADSORPTION RATIO (SAR) (2006 Version)

(1) No person may violate the numeric water quality standards or the criteria for determining 

nonsignificant changes in water quality identified in (2) through (6). 

(2) The numeric standards for electrical conductivity (EC) and sodium adsorption ratio (SAR) for the 

mainstems of Rosebud Creek, the Tongue, Powder, and Little Powder rivers from November 1 through 

March 1 are as follows: 

(a) for Rosebud Creek and the Tongue River, the monthly average numeric water quality standard for EC 

is 1500 μS/cm and no sample may exceed an EC value of 2500 μS/cm. The monthly average numeric 

water quality standard for SAR is 5.0 and no sample may exceed an SAR value of 7.5; and 

(b) for the Powder River and the Little Powder River, the monthly average numeric water quality standard 

for EC is 2500 μS/cm and no sample may exceed an EC value of 2500 μS/cm. The monthly average 

numeric water quality standard for SAR is 6.5 and no sample may exceed an SAR value of 9.75. 

(3) The numeric standards for EC and SAR for the mainstems of Rosebud Creek, the Tongue, Powder, 

and Little Powder rivers from March 2 through October 31 are as follows: 

(a) for Rosebud Creek and the Tongue River, the monthly average numeric water quality standard for EC 

is 1000 μS/cm and no sample may exceed an EC value of 1500 μS/cm. The monthly average numeric 

water quality standard for SAR is 3.0 and no sample may exceed an SAR value of 4.5; and 

(b) for the Powder River and Little Powder River, the monthly average numeric water quality standard for 

EC is 2000 μS/cm and no sample may exceed an EC value of 2500 μS/cm. The monthly average numeric 

water quality standard for SAR is 5.0 and no sample may exceed an SAR value of 7.5. 

(4) For all tributaries and other surface waters in the Rosebud Creek, Tongue, Powder, and Little Powder 

river watersheds, the monthly average numeric water quality standard for EC is 500 μS/cm and no 

sample may exceed an EC value of 500 μS/cm. The monthly average numeric water quality standard for 

SAR from March 2 through October 31 is 3.0 and no sample may exceed an SAR value of 4.5. The 

monthly average numeric water quality standard for SAR from November 1 through March 1 is 5.0 and no 

sample may exceed an SAR value of 7.5. 

(5) For the Tongue River Reservoir, the monthly average numeric water quality standard for EC is 1000 

μS/cm and no sample may exceed an EC value of 1500 μS/cm. The monthly average numeric water 

quality standard for SAR is 3.0 and no sample may exceed an SAR value of 4.5. 

(6) EC and SAR are harmful parameters for the purposes of the Montana Water Quality Act, Title 75, chapter 5, 

MCA. (History: 75-5-301, 75-5-303, MCA; IMP, 75-5-301, 75-5-303, MCA; NEW, 2003 MAR p. 779, Eff. 

4/25/03; AMD, 2006 MAR p. 1733, Eff. 5/19/06.)
HYDROLOGY APPENDIX

EC and SAR Standards

HYD-12

Montana Board of Environmental Review 

March 23, 2006 Decisions Concerning New CBNG Water Quality Rules

Adopted

The Montana Board of Environmental Review (BER) adopted new rules for EC and SAR to be changed to harmful 

parameters. This designation triggers the non-degradation criteria under the Montana Pollutant Discharge 

Elimination System (MPDES) permitting process. It is consistent with Montana’s management of other parameters 

with numerical water quality standards. The essence of the non-degradation criteria is to protect high quality state 

waters and limit discharges so changes to water quality would always result in levels of "harmful parameters" (in 

this case EC and SAR) between existing water quality levels and 40% of the existing water quality standards (there 

is also a 10% change limit for any discharge). For example, if the water quality standard is 1000 uS/cm a discharge 

permit would need to result in an instream water quality (after the mixing zone) not greater than 400 uS/cm. 

Whenever ambient conditions exceed 40% of the existing standards, no assimilative capacity is available, and any 

discharges resulting in a measurable increase would not be permitted (can not cause an increase, but could keep it 

the same or make it less). It should be noted that the three CBNG permits into the Tongue River already use up most 

of the assimilative capacity there.

This rule would apply statewide, however it is only effective at this point on water bodies with numeric water 

quality standards for EC and SAR (i.e., Tongue, Powder, Little Powder, and Rosebud watersheds).

Companies would have to treat water in the Tongue River to SAR and EC levels comparable to ambient water 

quality, which is below the existing standards if they wanted to discharge to waters of the state. Discharges into the 

Powder River and Little Powder River would also be limited because the ambient conditions in these water bodies 

often exceed 40% of existing standards. Plans for treating water by companies operating in Montana that have been 

approved by the Montana Department of Environmental Quality (MDEQ) involve treating water to a very low SAR, 

approximately 0.04, and EC to about 233 uS/cm and then mixing at a rate (approximately 75% treated water to 25% 

untreated water) to meet instream water quality standards at the end of pipe. Adoption of the proposed rule would 

probably require treatment of more water overall and curtail the ability to blend treated with untreated water before 

discharging. 

The Wyoming DEQ would also be required to meet the non-degradation standards at the state line if the Montana 

standards are approved by the EPA.

The only way to obtain a permit if the 40% or 10% thresholds are exceeded would be to obtain a permit from the 

MDEQ to degrade. Although the MDEQ has a method for processing a permit to degrade, no such permits have ever 

been requested by any party in Montana.

Rejected

The BER rejected the portion of the proposed rule that requires injection of CBNG produced water and a rigorous 

process to bypass the requirement to use injection.

The Environmental Quality Council determined the proposed rule requiring CBNG companies to use injection as the 

initial method for disposal of produced water is outside of the jurisdiction of the Montana BER. Comments on the 

proposal from the public; the Environmental Quality Council findings; and the State’s review (Montana Bureau of 

Mines and Geology Study) of the feasibility of injection in the Power River Basin are all reasons this portion of the 

rule was rejected.

Other Actions 

The BER adopted the rule deleting the requirement to use a flow-based permit calculation method, and rejected the 

proposed rule to use the 7Q10 flow (lowest flow conditions). The MPDES section of the MDEQ has the discretion 

to use either method for calculating approved discharges for other MPDES permits, and has used both. This action 
HYDROLOGY APPENDIX

EC and SAR Standards

HYD-13

preserves the MDEQ’s discretion to use either, or a combination of the two, and makes the analysis and calculation 

of CBNG produced water permits consistent with other MPDES efforts.

The BER postponed ruling on the requirement to treat CBNG waters and the effluent limits proposed for treatment. 

The BER directed the MDEQ to return a proposal to the Board on this matter after performing additional analysis of 

proposed effluent limitations and documentation of the technical, economic, and environmental feasibility and costeffectiveness of those effluent limitations. This matter is scheduled to be presented to the BER at its September 29, 

2006 meeting. 

On March 10, 2006, the Northern Plains Resource Council (NPRC) proposed amending its own petition regarding 

effluent limits with an EPA-recommended statistical approach. This was proposed in response to numerous 

comments received on effluent limits of the proposed rule. The NPRC’s March 10 proposal also included exceptions 

to a requirement to treat CBNG water for any permitted beneficial uses. No interested parties were provided an 

opportunity to review or comment on the amended language provided by the NPRC. The BER did not consider the 

March 10 proposal a part of the proposed rule making under review. 
HYD-14

EC HYDROLOGY APPENDIX

and SAR Standards

WQS for Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR) Adopted by the Northern Cheyenne Tribe

The Northern Cheyenne Tribe’s EC and SAR numerical standards were adopted by the Tribal Council on May 28, 2002. The numerical standards apply to the 

Tongue River, Rosebud Creek and tributaries to each within the boundaries of the Reservation.

Tongue River and Rosebud 

Creek (within the Reservation 

Boundaries)

Irrigation Season

(4/1 - 11/15) Criteria Applicable All Year Notes

EC (30-day ave.) EC (inst. max.) SAR (inst. max.) The Tribe has also adopted 

indicator values for total 

dissolved solids (TDS) that 

will be used to monitor 

conditions and trends of these 

waters.

Southern Boundary 1000 2000 2.0

Northern Boundary 1500 2000 3.0

Tributaries 1500 2000 3.0
HYDROLOGY APPENDIX

Example Water Mitigation Agreement 

HYD-15

EXAMPLE WATER WELL MITIGATION AGREEMENT

WHEREAS, Owner has existing water wells within its property boundaries, providing Owner water 

for domestic and agricultural/livestock water, and 

WHEREAS, Operator has acquired leases for the development of Coalbed Natural Gas (CBNG) and 

intends to drill and complete wells for production of CBNG, and

WHEREAS, the development and production of CBNG usually requires the production of water in 

conjunction with CBNG and may require the localized reduction of water levels within certain 

individual strata of the Ft. Union Coals, and

WHEREAS, Operator has advised Owner that the production of water in association with gas could 

adversely affect the productive capacity of Owner’s existing water wells which draw water from the 

Ft. Union aquifer.

NOW, THEREFORE, as consideration for the mutual covenants herein, in order to facilitate the 

multiple usage of the natural resources consistent with sound environmental practices, to mitigate 

potential adverse affects on the Owner’s water wells, to assure prompt and effective remediation, 

and to reduce the need for regulatory intervention by State and Federal agencies, the Owner and 

Operator agree as follows:

DEFINITIONS

Ft. Union Coals – The Ft. Union Coals, as used herein, shall mean those individual coalbeds or 

several coal beds contained within the Tongue River member of the Ft. Union Formation, bounded 

above by the Wasatch Formation of Eocene, and below by the Lebo Shale member.

Circle of Influence (COI) – The area that falls within a circle, the center of which is the location of a 

producing CBNG well, which has a radius of one mile (5,280 feet).

Impaired Water Well – Any water well or spring existing on the Owner’s property within the COI, 

existing at the time of the CBNG development, that experiences a reduction of capacity to deliver 

water in quantity and/or quality sufficient to support the ordinary and customary use of the well or 

spring.

Strat Test – Any test well that is drilled with the purpose of obtaining geologic information that is not 

completed for production and is subsequently plugged and abandoned. Strat test may produce water 

and/or gas for a period not to exceed thirty (30) days without creating a COI.

CBNG Well – Any well drilled and completed for the production of CBNG that withdraws water 

and/or gas and water from the aquifer for a period exceeding sixty (60) days.
HYDROLOGY APPENDIX

Example Water Mitigation Agreement 

HYD-16

AGREEMENT

1. Upon the establishment of a COI, the Operator, at its sole cost and risk, will measure, or 

cause to be measured, the static water level and productive capacity (“the baseline 

measurement”) of all water wells and springs within the COI and will attempt to determine 

the depth and configuration of these wells through consultation with the Owner and from the 

records of the Montana Department of Natural Resources. Upon request, Owner shall 

provide Operator with the location of all wells and springs within one mile of Operator’s 

drilling operations. The Operator shall also test for the presence of methane in the water 

wells.

2. Owner shall, upon reasonable notice, allow the testing of water wells and springs within COI, 

including a static water level test which may require the cessation of withdrawals of water 

from the well or spring for a period not to exceed twenty-four (24) hours.

3. Operator shall establish a continuing water well monitoring program, the intent of which is to 

enable the Operator to identify changes in capacity of the Owner’s water wells and springs 

within the COI. The Owner shall allow continued periodic testing of the water wells and 

springs within the COI for this purpose. Operator shall immediately provide all test data, both 

“baseline data” and monitoring data, to the Owner as it is acquired by Operator.

4. If a water well or spring within the COI becomes impaired as defined herein, Owner shall first 

take reasonable steps to verify that the impairment is not due to mechanical, electrical, down 

hole integrity, or pump problems, and, if none of these problems appear to be the cause of 

the impairment, Owner shall notify Operator of the impairment. Notice shall be made by 

phone and by writing, delivered by hand or by registered mail to the Operator at the above 

address.

5. Within sixty (60) days of the receipt of notice of impairment, Operator shall restore the 

Owner’s access to water of sufficient quantity and quality to offset such impairment by 

reconfiguring, redrilling the well, the drilling of a new well, or by other means. It is recognized 

that additional power costs may be associated with any reconfiguration of an impaired water 

well which additional power costs shall be paid for by the Operator. The specific site of the 

well or water access may be changed by mutual agreement of Operator and Owner.

6. Operator agrees that upon notice of impairment and during the curative period, to provide 

and make available water for domestic and livestock usage in quantity, quality, and location 

required for the maintenance of normal and customary domestic, grazing, and livestock 

operations. Operator shall develop emergency procedures for immediate delivery of water to 

any such affected Owner within twenty-four (24) hour emergency contact. Owner shall make 

a good faith effort to inform Operator, by phone, fax, or other expedient method of 

communicating, of any impending loss or damage to livestock, allowing Operator a 

reasonable opportunity to mitigate such damage.

7. In the event it is determined that there is an impaired water well or spring, as defined above, 

in any COI, that COI shall be expanded based on the location of the impaired wells or 

springs. The COI shall be divided into quadrants (NE, NW, SW, SE) and based upon which 

quadrant the impaired water well or spring is located in, that quadrant shall be expanded by 

the area included within a arc one-eighth (1/8) of a miles wide (660 feet) outside the existing 

COI. Likewise, should it be determined that there is an impaired water well or spring within 

the expanded quadrant of the COI, that quadrant shall be again expanded by another 660 

feet increment. This expansion approach shall be used to expand any COI in any direction 

where impairment is determined during the life of the CBNG well. Notwithstanding the 

above, if no water well or spring exists within the expanded area, the arc and associated 

quadrant shall be expanded to included the next nearest water well or spring.
HYDROLOGY APPENDIX

Example Water Mitigation Agreement 

HYD-17

8. At any time that the Lessee undertakes activities to enhance Owner’s water well capacity or 

to restore Owner’s impaired water well capacity, and should such activities require permits 

from regulatory agencies or permissions from third parties for surface entry, Owner shall aid 

and assist Operator in the obtaining of permits and permissions necessary to conduct the 

operations. All costs of the operations, including fees for obtaining permits and permissions, 

shall be borne by the Operator.

9. In the event that the interpretation or enforcement of this Agreement results in legal action, 

the costs of such action, including reasonable attorneys’ fees, shall be borne by the 

individual parties, except in the event that the Owner is the prevailing party, in which case 

the Operator shall bear the costs and attorneys fees of the Owner.

10. The terms and provisions contained herein shall run with the land and shall be binding on 

the heirs, successors, and assigns of Owner and Operator. This Agreement shall terminate 

upon the expiration of the last Oil and Gas Lease or the Plugging and abandonment of the 

last CBNG well to which this Agreement applies, whichever is the later date.

This Agreement may be executed in any number of counterparts, each of which shall be considered 

an original.

OWNER: OPERATOR:

Owner Company

By:__________________________________ By:___________________________________
HYDROLOGY APPENDIX

MCA 82-11-175 CBM Well Requirements

HYD-18

Montana Code Annotated 2005

TITLE 82. MINERALS, OIL, AND GAS

CHAPTER 11. OIL AND GAS CONSERVATION

Part 1. Regulation by Board of Oil and Gas Conservation

Sub-Part 175

 82-11-175. Coal bed methane wells -- requirements.

(1) Coal bed methane production wells that involve the production of ground water must comply with this 

section. 

(2) Ground water produced in association with a coal bed methane well must be managed in any of the 

following ways: 

(a) used as irrigation or stock water or for other beneficial uses in compliance with Title 85, 

chapter 2, part 3; 

(b) reinjected to an acceptable subsurface strata or aquifer pursuant to applicable law; 

(c) discharged to the surface or surface waters subject to the permit requirements of Title 75, 

chapter 5; or

(d) managed through other methods allowed by law. 

(3) (a) Prior to the development of a coal bed methane well that involves the production of ground 

water from an aquifer that is a source of supply for appropriation rights or permits to appropriate 

under Title 85, chapter 2, the developer of the coal bed methane well shall notify and offer a 

reasonable mitigation agreement to each appropriator of water who holds an appropriation right or 

a permit to appropriate under Title 85, chapter 2, that is for ground water and for which the point 

of diversion is within: 

(i) 1 mile of the coal bed methane well; or 

(ii) one-half mile of a well that is adversely affected by the coal bed methane well. 

(b) The mitigation agreement 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. The mitigation agreement is not required to 

address a loss of water well productivity that does not result from a reduction in the amount of 

available water because of production of ground water from the coal bed methane well. 

 History: En. Sec. 4, Ch. 578, L. 2001; Sec. , MCA 2001; redes. by Sec. 1, Ch. 117, L. 2003. 
HYDROLOGY APPENDIX

CBM Protection Act

HYD-19

Montana Code Annotated 2005

TITLE 76. LAND RESOURCES AND USE 

CHAPTER 15. CONSERVATION DISTRICTS 

Part 9. Coal Bed Methane Protection Program 

76-15-901. Short title. This part may be cited as the "Coal Bed Methane Protection Act".

76-15-902. Legislative findings and declaration of purpose.

(1) The legislature finds that the need for an economical supply of clean-burning energy is a 

national and state priority. 

(2) The legislature further finds that Montana possesses plentiful reserves of clean-burning natural 

gas contained in coal beds. 

(3) The legislature further finds that the extraction of natural gas from coal beds may result in 

unanticipated adverse impacts to land and to water quality and availability. 

(4) The legislature declares that there is a compelling public need to promote efforts that preserve 

the environment and protect the right to use and enjoy private property. The legislature further 

declares that the purpose of this part is to establish a long-term coal bed methane protection 

account and a coal bed methane protection program for the purpose of compensating private 

landowners and water right holders for damage to land and to water quality and availability that 

is attributable to the development of coal bed methane wells. 

(5) The legislature further declares that the provisions of this part do not relieve coal bed methane 

developers or operators that own, develop, or operate coal bed methane wells and collection 

systems of their legal obligation to compensate landowners and water right holders for damages 

caused by the development of coal bed methane. 

(6) The legislature further declares that the provisions of this part do not relieve coal bed methane 

developers or operators from: 

(a) any liability associated with the exploration or development of coal bed methane; or 

(b) the responsibility to comply with any applicable provision of Titles 75, 82, and 85 and 

any other provision of law applicable to the protection of natural resources or the 

environment.

76-15-903. Definitions. As used in this part, unless the context requires otherwise, the following 

definitions apply: 

(1) "Agricultural production" means the production of: 

 (a) any growing grass, crops, or trees attached to the surface of the land; or 

 (b) farm animals with commercial value. 

(2) "Coal bed methane developer or operator" means the person who acquires a lease for the 

purpose of extracting natural gas from a coal bed. 

(3) "Department" means the department of natural resources and conservation as provided for in 

Title 2, chapter 15, part 33. 

(4) "Emergency" means the loss of a water supply that must be replaced immediately to avoid 

substantial damage to a landowner or a water right holder.

76-15-904. Coal bed methane protection account -- use.

(1) There is a coal bed methane protection account in the state special revenue fund. 

(2) There must be deposited in the account the proceeds from the distribution of oil and natural 

gas production taxes, as provided in 15-36-331. 

(3) All money paid into the account must be invested by the board of investments. Earnings from 

investments must be deposited in the account. 

(4) Subject to the conditions of subsection (5), money deposited in the account must be used to 

compensate landowners and water right holders for damages attributable to coal bed methane 

development as provided in this part. 
HYDROLOGY APPENDIX

CBM Protection Act

HYD-20

(5) Money deposited in the fund and earnings of the fund may not be expended until after June 

30, 2005. For fiscal years beginning after June 30, 2005, principal and earnings may be 

expended only in the case of an emergency. For fiscal years beginning after June 30, 2011, 

principal and earnings in the account may be expended for any purpose authorized pursuant to 

this part. 

(6) Money in the account must be appropriated to the department for use by conservation districts 

that have private landowners or water right holders who qualify for compensation as provided 

in 76-15-905. (Subsection (2) terminates June 30, 2011--sec. 10, Ch. 531, L. 2001.)

76-15-905. Coal bed methane protection program -- restrictions.

(1) There is a coal bed methane protection program administered by conservation districts that 

have coal beds within the exterior boundary of the district or whose water sources may be 

adversely affected by the extraction of coal bed methane. The purpose of the coal bed 

methane protection program is to compensate private landowners or water right holders for 

damage caused by coal bed methane development. 

(2) A conservation district shall establish procedures, approved by the department, for evaluating 

claims for compensation submitted by a landowner or water right holder. The procedures 

must include: 

(a) a method for submitting an application for compensation for damages caused by coal 

bed methane development; 

(b) a process for determining the cost of the damage to land, surface water, or ground 

water, if any, caused by coal bed methane development; 

(c) the development of eligibility requirements for receiving compensation that include 

an applicant's access to existing sources of state funding, including state-mandated 

payments, that compensate for damages; and 

(d) criteria for ranking applications related to available resources. 

(3) An eligible recipient for compensation includes private landowners and water right holders 

who can demonstrate as the result of damage caused by coal bed methane development: 

 (a) a loss of agricultural production or a loss in the value of land; 

(b) a reduction in the quantity or quality of water available from a surface water or

ground water source that affects the beneficial use of water; or 

(c) the contamination of surface water or ground water that prevents its beneficial use. 

(4) (a) Subject to the conditions of subsections (5) through (8), an eligible landowner may be 

compensated for the damages incurred by the landowner for loss of agricultural 

production and income, lost land value, and lost value of improvements caused by coal 

bed methane development. A payment made under this subsection (4)(a) may only cover 

land directly affected by coal bed methane development. 

(b) Subject to the conditions of subsections (5) through (8), an eligible water right holder 

may be compensated for damages caused by the contamination, diminution, or 

interruption of surface water or ground water. 

(5) In order to qualify for a payment of damages under this section, the landowner or water right 

holder shall demonstrate that it is unlikely that compensation will be made by the coal 

bed methane developer or operator who is liable for the damage to land or the reduction 

in or contamination of surface water or ground water as the result of coal bed methane 

development. 

(6) Compensation made to a landowner or a water right holder under this section may not exceed 

75% of the cost of the damages. The maximum amount paid to a landowner or water 

right holder may not exceed $50,000. 

(7) Conservation district administrative expenses for services provided under this section are 

eligible costs for reimbursement from the coal bed methane protection account. 

(8) (a) Except as provided in subsection (8)(b), compensation for damages allowed under this 

section may be made only after June 30, 2011. 

(b) Compensation for an emergency may be made after June 30, 2005.