Water Resources of Idaho
Water Resources of Idaho |
The Northern Rockies NAWQA will increase the scientific understanding of surface- and ground-water quality and the factors that influence water quality. This information will benefit the water-resource managers that need, but often lack, the data required to implement effective water-quality management actions and evaluate long-term changes in water quality.
Water-quality improvements in the study area have been identified and these may be related to improvements in mining, forestry, agricultural-related activities, and the treatment of municipal and industrial wastes. However, the effects of land-use and water- use practices on many rivers and ground-water resources remain a priority concern to water- resource managers, planners, State and local governments, and citizen groups.
The following water-quality issues have been identified by water-resource managers as high priority, regional-scale issues of concern:
The quality of surface water and ground water in the watersheds of both the Clark Fork-Pend Oreille and Spokane Rivers (figure 2) is affected by mining wastes or tailings. In the Clark Fork drainage, tailings have been transported and deposited along more than 150 miles of river channel and flood plain from Butte to near Missoula. Similarly, tailings discharged directly to the South Fork Coeur d'Alene River have been transported and deposited along the river channel and flood plain into Lake Coeur d'Alene, and potentially out of the lake and along the Spokane River. Mine tailings in the study area typically contain elevated concentrations of the trace metals arsenic, cadmium, copper, lead, and zinc. Six major fish kills in the upper Clark Fork since 1984 and the scarcity of bottom- dwelling organisms in Lake Coeur d'Alene have been attributed to the toxic effects of these trace metals. Public water supplies from the alluvial aquifer near Milltown Reservoir have been abandoned because of arsenic contamination which may come from tailings accumulated in bottom sediments of the reservoir.
The quality of surface water also is affected by nutrients and sediment. Nitrogen and phosphorus concentrations sometimes exceed criteria for biological enrichment in the Clark Fork headwaters. Nutrient enrichment and potential eutrophication are of concern for Flathead Lake, Lake Pend Oreille, and Lake Coeur d'Alene, where residential and commercial shoreline development and recreational use are rapidly increasing. Sources of nutrients include municipal wastes, septic-system effluent, and soil erosion from timber-harvest activities and agriculture. Increased sediment loads from timber harvesting and attendant road building, and from agriculture may be responsible for declines in populations of native trout species.
The Missoula and Spokane Valley/Rathdrum Prairie aquifers have been designated as sole- source aquifers by the U.S. Environmental Protection Agency. In many areas these coarse-grained aquifers are susceptible to contamination. Whereas the quality of water in these alluvial aquifers generally is good, some parts of these aquifers have been adversely affected by human activities.
Information on these issues can be found on the NROK Publications page.
U.S. Department of the Interior | U.S. Geological Survey
URL: id.water.usgs.gov/nrok/issues.htm
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Page Last Modified: Wednesday, 22-Apr-2009 14:16:33 EDT