Water-Related Issues in Montana

Effects of Abandoned or Inactive Mine Lands on Water Resources

Mining for precious metals in Montana began in the mid-1800’s and had a major influence on the settlement and economic development of the State.  Although mining activity has decreased in recent years, numerous sites in mountainous areas throughout western and central Montana have been disturbed as a result of past mining activities.  Many of these sites, most of which are now abandoned or inactive, are on or adjacent to Federal lands and affect resources on those public lands.

Current Activities

In 1995, an interdepartmental strategy was developed to address the remediation of affected areas on public lands.  The strategy uses a watershed approach, and is focused on developing methods to understand the processes that release and transport acid and metals to streams and the subsequent response of biological communities.  The USGS is working closely with the U.S. Forest Service (USFS) and the Bureau of Land Management (BLM) to develop efficient and cost-effective methods to evaluate effects and formulate plans for remediation.  A multidisciplinary pilot study for this strategy was initiated in 1997 in the Boulder River watershed in Montana.   The pilot study is scheduled for completion in 2003.  The results of the multiple scientific investigations conducted as part of this study will be synthesized and published in a U.S. Geological Survey Professional Paper.  Successes in the pilot study have led to the development of additional studies of various scopes in cooperation with the USFS and/or U.S. Environmental Protection Agency (EPA) in the Prickly Pear Creek, Tenmile Creek, Soda Butte Creek, Miller Creek, Fisher Creek, and Daisy Creek watersheds in Montana. 

Effects of Coal-Bed Methane (CBM) Development on Water Resources

The Powder River Basin in Montana, Wyoming, and North Dakota contains vast coal resources.  Although coal mining has been active in the Basin for decades, the recovery of methane from coal beds has recently emerged as a rapidly expanding method of natural-resource extraction.  The methane is contained in solution and on cleat surfaces within the coal bed and held in place by hydraulic pressure.  Lowering of the hydraulic pressure by withdrawal of water from wells completed in the coal bed allows the methane to be released and recovered.  About 200 such wells have been permitted in Montana and permit applications for as many as 16,000 more wells are possible over the next 10 years.  Data indicate that each of these wells will produce about 2.5 gallons per minute of ground water on average over an estimated 20-year life of the well.

The large existing and potential future withdrawals of water can have numerous effects on ground water and surface water.  Many of the coal beds serve as aquifers, and decreasing water levels from the large-scale withdrawals can cause wells used for domestic and livestock supplies to become unproductive and result in decreases of ground-water inflow to streams.  The large-scale withdrawals can also affect the discharge characteristics of small streams and could have a detrimental effect on the quality of water in large streams, such as the Tongue River and Powder River, which are sources of irrigation water.

Current Activities

The Montana District continues to organize meetings of technical representatives of Federal, State, and tribal agencies involved in natural-resource assessment and management to discuss needs and concerns and to coordinate efforts for monitoring and assessing the potential effects on water and other resources in areas of existing or anticipated coal-bed methane development.  Surface-water data collection continues at numerous sites in the Tongue and Powder River watersheds, including three sites that have been equipped with continuous specific-conductance monitors.  We’re completing a study to document current stream-channel morphology along the Tongue River for later comparison to determine if flow alterations resulting from CBM development are affecting channel morphology.  In 2002 we began a study to establish a ground-water-monitoring network along the southern edge of the Northern Cheyenne Reservation to detect changes in water levels in the coal aquifers on the reservation resulting from CBM development. During the installation of the monitoring wells, the coals were be cored and the cores were tested for gas desorption by members of the USGS Central Region Energy Team.  In addition, in 2002, we participated in an interdisciplinary effort to examine the possible effects of CBM development on wetlands in the Tongue River watershed and began a reconnaissance level surface-water sampling effort on six to ten small streams along the eastern edge of the Crow Reservation.

Effects of Population Growth on the Water Resources in Intermontane Valleys

The population of much of western and south-central Montana is increasing rapidly.  Some of the increase is occurring in cities—such as Bozeman, Missoula, Kalispell, and Helena—but much of the increase is occurring outside of established cities and towns, in areas such as the Gallatin, Bitterroot, Missoula, Paradise, Flathead, and Helena Valleys.  Population increases in cities create additional demands on public water supplies and larger sewage outflows, which can affect the quantity and quality of surface water.  Population increases in suburban or rural settings typically create additional demands on ground water for individual supplies and additional stresses on ground-water quality through the use of individual septic systems.  Septic systems may leach nitrates, wastewater compounds such as pharmaceuticals, and even bacteria and viruses into shallow aquifers.

Most ground-water supplies in the intermontane valleys are obtained from alluvial aquifers, which are typically hydraulically connected to local streams and rivers.  In some areas, ground-water systems are also recharged by irrigation of agricultural land.  Conversion of this agricultural land to residential subdivisions decreases or ends ground-water recharge from irrigation and can alter the ground-water flow system in these areas.  The existing and potential effects of the increase in population are of significant concern to resource managers, planners, developers, and the general public.  Although the general hydrologic characteristics of many of these areas are known, a much more detailed understanding is needed to address these concerns and to allow for protection and wise development of the water resource.

Current Activities

We have recently completed studies in the Helena and Gallatin valleys examining these issues.  The results of each study were documented in a Water-Resources Investigations Report and a Fact Sheet.  We continue to work with local officials in the affected areas seeking funding for studies to address the many questions that remain unanswered regarding the impact of rapid population growth on water resources.

Stream-Channel Geomorphology and Hydraulic Analysis

Streams and their flood plains comprise dynamic systems that support a variety of important domestic, agricultural, industrial, and recreational uses.  Natural and anthropogenic factors affect these systems in complex ways that can be detrimental to one or more of their beneficial uses.  Record high streamflows, large-scale contamination remediation efforts, increased residential and recreational development along streams, and numerous man-made small- to moderate-scale channel modifications have affected many stream channels in Montana. Landowners, recreationists, and resource managers are increasingly voicing their concerns about these effects and requesting comprehensive analysis of stream-channel geomorphology and hydraulics. 

Current Activities

We are completing a study to analyze the hydraulic characteristics of the upper Yellowstone River as part of a multi-agency effort to determine the cumulative effects of numerous channel changes and provide a scientific basis for future decisions regarding channel modifications.  We’re also completing a study to improve regression equations for estimation of peak discharge in western Montana by including other channel geomorphological features such as bankfull depth in the regression analysis.  Improving these regression equations should aid cooperators and others who are involved in stream-restoration projects.  We’re also finishing up a study to define the geomorphology of the Tongue River and selected tributaries in Montana.  The objective of the study will be to document current channel morphology before the potential discharge of large quantities of water produced to

Surface-Water-Quality Monitoring and Assessment

Interest in surface-water quality continues to increase as the number of activities related to the Clean Water Act increases.  Because of several lawsuits related to TMDLs, the State of Montana and EPA have increased funding for surface-water-quality monitoring activities.  Many stream segments in Montana are listed on the State’s 303(d) list because of excessive concentrations of sediment, nutrients, and trace metals.  TMDLs will need to be developed to address each of these listed stream segments and constituents in order to improve the quality of the water in the State’s streams and rivers.

Current Activities

In 1999, a fixed-station surface-water-quality monitoring network was established jointly by the USGS and Montana Department of Environmental Quality (MDEQ) to gather data on long-term surface-water quality and trends for the State’s streams.  The network consists of 37 stations:  several of these stations currently are operated as part of other USGS programs, such as NASQAN, NAWQA, or cooperative programs.  The network is scheduled for long-term operation. 

Effects of Drought on Water Resources

As parts of Montana begin the fifth consecutive year of drought, the public is becoming increasingly concerned about water availability for domestic and agricultural use.  Changing climatic conditions resulting from recent El Nino and La Nina events have altered the typical amount, timing, and distribution of precipitation in Montana.  Several of the State’s reservoirs have been depleted by this string of dry years limiting the availability of irrigation water to ranchers and farmers.  The ongoing drought will continue to have an impact on ground-water levels and streamflows even if the state receives an average amount of precipitation this year or next.

Current Activities

The USGS-Montana District has been a non-voting member of the Montana Drought Advisory Committee since it was established in 1991.  Our primary role has been to brief the Committee on current streamflow conditions.  Our most significant drought-related activity is to measure streamflow at hundreds of locations statewide.  As surface-water becomes scarce, accurate and timely streamflow measurements are critical to management of the resource.  During the recent drought years we have been very responsive to the needs of the citizens of Montana for streamflow information.  We have made many extra streamflow measurements to refine stage-discharge relations at low stages and have quickly installed additional streamgages when requested.  We have also been providing pictures of drought-impacted streams to the maintainers of the Montana Drought Advisory Committee’s web page.

Changes in Hydrology Caused by Wildfires

During the 2000 and 2001 fire seasons more than 1 million acres of Montana’s forests burned.   Some areas were burned very severely and all foliage was removed.  In many of these severely burned areas the soil was heated so much that it became impermeable.  The removal of foliage and changes in soil permeability altered the drainage-basin characteristics in these areas making these watersheds much more susceptible to flash flooding and debris flows during intense rainstorms.  Intense rainstorms in these areas also mobilize large volumes of ash-laden sediment that can be a significant water-quality concern.

Current Activities

In the summer of 2001, we documented several large flood events on small, severely burned watersheds.  Working with USGS-Geology discipline staff, we also investigated numerous debris flows in the same areas.  We have installed sixteen tipping-bucket rain gages, five crest-stage gages, and three continuous streamflow gages in burned watersheds throughout the State.  Water-quality monitoring was initiated at two stations in the Bitterroot Valley and one in the Flathead Valley to look for water-quality changes resulting from fires in these areas.