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ANALYSIS OF DATA ON NUTRIENTS AND ORGANIC COMPOUNDS IN GROUND WATER IN THE UPPER SNAKE RIVER BASIN, IDAHO AND WESTERN WYOMING, 1980-91
Description:
Nutrient and organic compound data from the U.S. Geological Survey and the U.S. Environmental Protection Agency STORET data bases provided information for development of a preliminary conceptual model of spatial and temporal ground-water quality in the upper Snake River Basin (1704). Nitrite plus nitrate concentrations exceeded the Federal drinking-water regulation of 10 milligrams per liter in 3 areas in Idaho: the Idaho National Engineering Laboratory, the area north of Pocatello (Fort Hall area), and the area surrounding Burley. Water from many wells in the Twin Falls area also contained the highest median nitrate concentrations; water from industrial and public-supply wells contained the lowest. Nitrate concentrations decreased with increasing well depth, increasing depth to water, and increasing depth below water table. Kjeldahl nitrogen concentrations decreased with increasing well depth and depth below water table. The relation between kjeldahl nitrogen concentrations and depth to water was poor. Nitrate and total phosphorus concentrations in water from wells were correlated among three hydrogeomorphic regions in the upper Snake River Basin. Concentrations were correlated with land-use classifications developed using the Geographic Information Retrieval and Analysis System and classifications developed by the ID Department of Water Resources. Data were sufficient to assess long-term trends of nitrate concentrations in water from only 8 wells. The trend in nitrate concentrations in water from all wells is upward. The following organic compounds were detected in ground water in the upper Snake River Basin: cyanazine, 2,4-D, DDT, dacthal, diazinon, dichloropropane, dieldrin, malathion, and metribuzin. Of 211 wells sampled for organic compounds, water from 17 contained detectable concentrations. USGS Water-Resources Investigations Report 94-4135. Michael G. Rupert. 1994. 40 pp.