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ASSESSMENT OF SELECTED CONSTITUENTS IN THE SURFACE WATER OF THE UPPER SNAKE RIVER BASIN, IDAHO AND WESTERN WYOMING, WATER YEARS 1975-1989.
Description:
In 1991, a water-quality investigation of the upper Snake River Basin (1704) was initiated as part of the USGS National Water-Quality Assessment Program. Nearly 9,000 analyses of nutrients and suspended sediment from more than 450 stations were retrieved from the U.S. Environmental Protection Agency STORET and USGS WATSTORE data bases. 19 stations were analyzed, 4 located on relatively unaffected stream reaches, 8 at or near mouths of tributary basins affected by agricultural activities, 7 on the main stem of the Snake River. Nitrite plus nitrate and total phosphorus concentrations generally increased in a downstream direction along the Snake River; concentrations were largest at the mouths of drainage basins tributary to the Snake River. Concentrations of nitrite plus nitrate, total nitrogen, dissolved orthophosphate, and total phosphorus were significantly larger at agriculturally affected and main-stem stations than at unaffected stations; concentrations of nitrite plus nitrate, total nitrogen, and total phosphorus at agriculturally affected stations were significantly larger than at main-stem stations. Significant differences in seasonal concentrations of some nutrient species were noted. Few suspended sediment and pesticide data were available for the study basin. USGS Water-Resources Investigations Report 93-4229. Gregory M. Clark. 1994. 49 pp.