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Yellowstone River near Corwin Springs, MT


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Yellowstone River Basin

Project Description


NAWQA study units in the USAFederal, State, and local governments and industry have made significant commitments to the protection of water quality during the past two decades. Large financial investments have been made for water-quality management and protection and future expenditures are anticipated to abate and control water pollution. Nationally consistent information is needed to make valid regional comparisons and national statements about current water-quality conditions and about changes in these conditions. The U.S. Geological Survey began implementing a full-scale National Water-Quality Assessment (NAWQA) program in 1991 to address this need for national water-quality information. Assessing water quality in every area of the Nation would be impractical, thus major activities of the NAWQA program will take place within a set of hydrologic systems called study units. The Yellowstone River Basin was selected as 1 of 59 study units because

  • the basin represents an important hydrologic region where good-quality water is a valued resource vital to the region's economy,

  • the basin is one of the most important, unique, and/or threatened ecosystems in the Nation,

  • of high priority needs of other federal and non-federal agencies participating in the NAWQA advisory council.

Major Water-Quality Issues

Major water-quality issues in the Yellowstone River Basin vary from potential degradation of pristine streams in headwater areas to industrial and agricultural effects in downstream reaches, and include both point and non-point sources. The issues generally are related to land and water use, but some are related to natural factors. Potential water-quality issues to be investigated include

  • Trace elements - Leachate from mine spoils and tailings can increase trace elements in both ground and surface water. Leaching of soils derived from marine shales of cretaceous age in some locations has caused elevated concentrations of selenium in water resources. Geothermal source areas, like those in the Yellowstone National Park area, can be sources for elevated concentrations of trace elements, such as arsenic, in both ground and surface water. Concentrations of radionuclides in water resources are a concern because of the widespread distribution of uranium-bearing rocks in the basin. Trace elements and phosphorus also can be associated with suspended sediments in surface water.

  • Toxic compounds - Potential sources of toxic compounds in both ground and surface water include: leachate from abandoned and active landfills; pesticides and fertilizers from lawns and croplands; hydrocarbons from leaking tanks, refining operations, pipelines, and spills; and waste from industrial and commercial activities.

  • Salinity - Increases in the salinity of both ground and surface water can occur from saline ground water disposal, irrigation return flows, and some irrigation practices.

  • Sedimentation - Loss of streambank vegetation, easily erodible soils, and many land-use activities can contribute to sediment problems in streams throughout the basin.

  • Bacteria - Fecal coliform bacteria concentrations can exceed water-quality guidelines for streams. New guidelines are being considered for Escherichia coli, a species of bacteria associated with waste from warm-blooded animals.

  • Nutrient concentrations - Nutrient concentrations in streams can exceed guidelines for the prevention of nuisance algal growths. Excessive concentrations of algae can result in inadequate dissolved-oxygen concentrations and harmful effects to aquatic life, as well as impeding aesthetic properties and recreational uses.

  • Low-density residential development - Low-density residential development in the outskirts of communities has the potential to affect ground-water quality in these areas. Potential influences include leachate from septic systems; fertilizer and pesticide use on lawns, pastures, and gardens; manure from horses and pets; and increases in road construction and vehicle traffic.

  • Other water-related issues - There are many other water-quality issues in the basin including: acidification of water resources by leaching of industrial wastes, increased concentrations of nutrients in surface and ground water, localized de-watering of sole-source aquifers, potential water-quality problems related to coalbed methane production and water-related concerns on tribal lands.


Project activities in the NAWQA program are conducted in cycles to accomplish the objectives of the study. The first two years of the project focus on planning and analysis of available data. Years 3 through 5 emphasize data collection and analysis. A lower level of data collection continues for subsequent years to evaluate long-term trends in water quality. The Yellowstone River Basin Study is one of seventeen study units begun in 1997 as part of the NAWQA Program.

The Yellowstone River Basin NAWQA project is currently (2010) conducting low-intensity sampling of surface-water quality and aquatic ecology at site 06324970, Little Powder River above Dry Creek, near Weston, Wyo.

Planning is currently (2010) underway for a groundwater study related to agricultural land use (see special studies).

Study Unit Design

The nationwide design for the NAWQA program is described by Gilliom and others (1995). The NAWQA study units across the Nation share common protocols and goals (https://water.usgs.gov/nawqa/) for surface-water, ecological, and ground-water investigations. The study design of the Yellowstone River Basin NAWQA investigation includes national components and elements specific to this basin.

Surface-Water Chemistry and Ecology

The sampling network was designed to investigate water-quality characteristics of streams in the context of environmental settings in the Yellowstone River Basin (Zelt and others, 1999). Surface-water chemistry, aquatic ecology, bed sediment, and fish-tissue monitoring was conducted at fixed and intensive sampling sites noted in the table below. Additional bed sediment and fish tissue samples were collected at miscellaneous sites as part of an occurrence and distribution survey. Synoptic studies of bacteria and algal-nutrient relations also were conducted as noted on the next page. Streamflow and chemistry data for surface water, ground water, fish tissue, and bed sediment are available at: https://wy.water.usgs.gov/infodata/index.html. Taxonomic data for biota are available at: https://wy.water.usgs.gov/projects/yell/data.html.

Ground Water

The study design for the major aquifer surveys focused on the Bighorn Basin, an asymmetric structural basin about 22,000 square miles in areal extent within the larger Yellowstone River Basin. Water-chemistry samples were collected from wells completed in unconsolidated Quaternary deposits and in consolidated lower Tertiary rocks that are widespread in the Yellowstone River Basin. A land-use ground-water study was conducted in three areas of low-density residential development. The ground-water chemistry data are available at https://wy.water.usgs.gov/infodata/index.html.

Map of wells in the study area.

(Click on image for a larger version, 87 kb)

Table 1. (37Kb PDF file) Basic and intensive stream sampling sites, Yellowstone River Basin, 1999-2001.

Table 2. (58Kb PDF file) Stream chemistry, stream ecology, and ground water chemistry.

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Peter Wright
1728 Lampman Drive
Billings, Montana 59102
(406) 656-1444 X11
Email: prwright@usgs.gov

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