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Fact Sheet 2005–3137

Prepared in cooperation with the Montana Department of Environmental Quality

Surface-Water Monitoring in Watersheds of the Powder River Basin, 2005

By Melanie L. Clark¹, John H. Lambing¹, and Andrew L. Bobst²

¹U.S. Geological Survey
²Bureau of Land Management

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Powder River Basin Interagency Working Group

The Powder River Basin (PRB) is a geologic structural basin that contains an extensive natural gas resource associated with regional coal deposits. This coalbed natural gas (CBNG) is located beneath millions of acres of private and public land in southeastern Montana and northeastern Wyoming (fig. 1). The PRB Interagency Working Group (IWG) was established in June 2003 as a forum to identify, discuss, and find solutions to issues of common concern to government agencies involved in permitting and monitoring CBNG development. The PRB IWG is led by the Bureau of Land Management (BLM) and is composed of managers and technical staff from local, State, tribal, and federal government agencies with land management, conservation, or regulatory responsibilities in the PRB, as well as agencies like the U.S. Geological Survey (USGS) that provide technical support. The mission of the PRB IWG is to: (1) provide for environmentally sound energy development, (2) develop coordinated and complementary best management practices, guidelines, and programs related to CBNG activities to conserve and protect resources, (3) monitor the impact of CBNG activities and assess the effectiveness of mitigating measures, (4) develop and integrate the databases and scientific studies needed for effective resource management and planning, and to make that information readily available, and (5) promote compatibility in the application of each agency’s mission. In order to more effectively address the technical issues presented by CBNG development, Task Groups that are staffed by technical specialists from the member agencies of the PRB IWG were formed to address specific resource issues. The Task Groups include Air, Aquatics, Water, and Wildlife. More information about the PRB IWG and Task Group activities is available at URL http://www.wy.blm.gov/bfo/prbgroup/index.htm.

Water Task Group

Substantial volumes of ground water are extracted from coalbeds in order to produce CBNG. The removal of ground water from aquifers and use or disposal of produced water on the surface have the potential to cause environmental impacts. One objective of the Water Task Group is to develop and implement monitoring plans for surface water and ground water at local and regional scales. This monitoring will help agencies make more informed decisions regarding CBNG permitting, and allow for dissemination of information to the public. This factsheet summarizes the surface-water-monitoring plan developed by the Water Task Group and describes the surface-water monitoring accomplished during 2005.

Surface-Water-Monitoring Plan

The surface-water-monitoring plan is a proposed sampling network that is generally composed of sites where PRB IWG member agencies have been conducting surface-water monitoring. Sampling sites may be located on mainstems or selected tributaries in each watershed (fig. 1, table 1). Proposed sampling frequencies vary with stream type and constituent class (table 2). The constituent classes recommended for monitoring include:

• Streamflow
• Field measurements—pH, dissolved oxygen, specific conductance, and temperature
• Major ions—dissolved calcium, magnesium, potassium, sodium, alkalinity, chloride, fluoride, sulfate, and silica; dissolved solids; and sodium-adsorption ratio
• Nutrients—total and dissolved nitrogen and phosphorus species
• Trace elements (primary)—total and dissolved aluminum, arsenic, barium, beryllium, iron, manganese, and selenium
• Trace elements (secondary)—total and dissolved cadmium, copper, chromium, lead, nickel, and zinc.
• Suspended sediment

Figure 1. Location of sampling sites proposed in the Water Task Group's surface-water-monitoring plan for the Powder River Basin.

Table 1. Sampling sites proposed in the Water Task Group’s surface-water-monitoring plan for the Powder River Basin.

Table 2. General sampling strategy proposed in the Water Task Group’s surface-water-monitoring plan for the Powder River Basin.

Monitoring Summary, 2005

Because of funding shortfalls for surface-water monitoring, only part of the proposed sampling in the surface-water-monitoring plan was accomplished during 2005 (table 3). For the sites where the sampling was partially completed, either the sampling frequency was less than the proposed sampling frequency or not all of the constituent classes were analyzed. The Tongue River watershed was the only watershed where the sampling proposed in the surface-water-monitoring plan was fully completed.

Several of the agencies that participate on the PRB IWG contributed funding for monitoring and reporting, including:

• BLM,
• Montana Department of Environmental Quality,
• Montana Department of Natural Resources and Conservation,
• Northern Cheyenne Tribe,
• U.S. Environmental Protection Agency,
• USGS,
• Wyoming Department of Environmental Quality, and the
• Wyoming State Engineer’s Office.

Streamflow data and water-quality samples were collected by USGS personnel using standard USGS field methods (http://water.usgs.gov/owq/FieldManual/). Samples were analyzed at the USGS National Water Quality Laboratory in Lakewood, Colorado.

Table 3. Monitoring accomplished for surface-water-monitoring plan during 2005.
[C, completed; P, partially completed; and N, not completed.]

Data Availability

Data collected as part of Water Task Group surface-water-monitoring plan are stored electronically in the USGS National Water Information System. Continuous streamflow and water-quality data are available to the public at URL: http://waterdata.usgs.gov/nwis/. Other USGS data for Montana and Wyoming can be accessed at http://mt.water.usgs.gov/, http://tonguerivermonitoring.cr.usgs.gov/, and http://wy.water.usgs.gov/.

Future Work

Another objective of the Water Task Group is to interpret the surface-water-monitoring data that are collected. Until more data are collected, much of the initial inter­pretive analysis may focus on sites with historical data that were collected for previous monitoring programs. For example, the Powder River at Arvada, Wyoming has been sampled for many years, and relations between constituents, such as specific conductance and the sodium-adsorption ratio, have been established (fig. 2). If the monitoring data indicate that water quality is changing, managers can use adaptive management and appropriate mitigation measures to address environmental concerns.

Figure 2. Specific conductance and sodium-adsorption ratio relation for the Powder River at Arvada, Wyo.

For more information, contact: Water Science Center Director, U.S. Geological Survey Montana Water Science Center 3162 Bozeman Avenue Helena, Montana 59601 Water Science Center Director, U.S. Geological Survey Wyoming Water Science Center 2617 E. Lincolnway, Suite B Cheyenne, Wyoming 82001 Field Office Manager, Bureau of Land Management Buffalo Field Office 1425 Fort Street Buffalo, Wyoming 82834-2436 Field Office Manager, Bureau of Land Management Miles City Field Office 111 Garryowen Road Miles City, Montana 59301

Layout by Suzanne C. Roberts

For additional information on the water quality of the Powder River Basin watersheds, visit the USGS Web site at http://wy.water.usgs.gov/

or contact

Director of the USGS Wyoming Water Science Center 2617 E. Lincolnway, Suite B Cheyenne, Wyoming 82001 (307) 775-9162 Email: state_rep_wy@usgs.gov