USGS

Water Quality in the Central Columbia Plateau, Washington and Idaho, 1992-95

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Summary of major issues and findings

|| Ground Water || Surface Water ||

Location map of the study unit

GROUND WATER: Ground water, the main source of drinking water, is substantially affected by agricultural practices.

Concentrations of nitrate in many wells exceed the drinking water standard (p. 6-8).

Pesticides are frequently detected, although generally at concentrations below drinking water criteria (p. 10-11).

Radon, a naturally occurring gas, is not increased by agricultural practices. Neither radon nor trace elements are a major concern in the Central Columbia Plateau.

Is ground-water quality improving?

Improvements from best management practices (BMPs) take decades or longer to be seen.

It is difficult to determine trends for pesticides because there are not enough data, but the patterns of detection may give some clues (p. 10).

SURFACE WATER: The health of the aquatic ecosystems is substantially affected by agricultural practices and, in a few streams, by wastewater discharges.

Eutrophication, caused by high concentrations of nutrients, is degrading streams (p. 17, 18).

Sediment erosion and runoff are degrading streams (p. 14-15, 19).

Riparian (streamside) habitat has been seriously reduced, and present-day agricultural practices limit natural recovery of the vegetation (p. 19).

Concentrations of agricultural pesticides occasionally exceed criteria for the protection of aquatic life in several streams (p. 12).

Is surface-water quality improving?

Soil erosion is decreasing as a result of best management practices (BMPs) (p. 14-15).

Although concentrations of nutrients are commonly still increasing, at some sites they have decreased slightly or begun to level off (p. 9, 17).


U.S. Geological Survey Circular 1144

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Suggested citation:
Williamson, A.K., Munn, M.D., Ryker, S.J., Wagner, R.J., Ebbert, J.C., and Vanderpool, A.M., 1998, Water Quality in the Central Columbia Plateau, Washington and Idaho, 1992-95: U.S. Geological Survey Circular 1144, on line at <URL: https://water.usgs.gov/pubs/circ1144>, updated March 3, 1998.

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Last modified: Thu Jun 4 15:34:37 1998