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MAJOR SOURCES OF NITROGEN INPUT AND LOSS IN THE UPPER SNAKE RIVER BASIN, IDAHO AND WESTERN WYOMING, 1990.
Description:
Total nitrogen input and loss from cattle manure, fertilizer, legume crops, precipitation, and domestic septic systems in the upper Snake River Basin, Idaho and western Wyoming (1704), were estimated by county for water year 1990. The purpose of these estimations was to rank input of nitrogen by source, determine the amount of total nitrogen potentially available to both ground and surface water through leaching and runoff, and identify areas in the basin where excess nitrogen is produced. The results of the input estimations suggest that domestic septic systems account for less than 1% of total nitrogen input in the basin and precipitation accounts for 6%. The remaining 93% is produced by cattle manure (29%), fertilizer (45%), and legume crops (19%). Input from these sources varies widely among counties and reflects differences in land-use practices such as different cropping patterns and numbers of dairies and feedlots. USGS Water-Resources Investigations Report 96-4008. Michael G. Rupert. 1996. 15 pp.