USGS Washington Water Science Center
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Stretching from Pendleton, Oreg., to the Columbia River, the Lower Umatilla Basin covers 550 square miles. Concentrations of nitrate in the basin's ground water frequently exceed national drinking-water standards. The basin's complex ground-water system is exposed to five human-related sources of nitrate: septic tanks, feedlots, explosives, fertilizer, and land applications of food waste.
To help resource managers in the the Lower Umatilla Basin Ground Water Management Area (GWMA), the USGS is developing tools to identify sources of nitrate in specific wells in the GWMA. The USGS is evaluating the effectiveness of tools that use isotopes and tracers to "fingerprint" the different sources of nitrate.