Water quality of the lower Columbia River basin; analysis of current and historical water-quality data through 1994

Water-Resources Investigations Report 95-4294

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This report, done by the U.S. Geological Survey in cooperation with the Lower Columbia River Bi-State Water-Quality Program, describes the water-quality conditions in the lower Columbia River Basin by interpreting data collected historically and in 1994. In 1994, arsenic, a human carcinogen, was detected in 15 of 16 samples in the lower Columbia River, but was not detected in any of the sampled tributaries. All 15 arsenic detections had concentrations that exceeded both the EPA ambient water-quality criteria for the protection of human health and the EPA human-health advisories for drinking water. Twenty organic compounds were detected of the 47 compounds analyzed for this study. None of the organic compounds detected exceeded EPA's ambient water-quality criteria or drinking-water guidelines. The largest concen- trations of the agricultural pesticides atrazine, metolachlor, and simazine were detected in the Willamette River, where they were detected in 85 to 90 percent of the samples collected. The largest concentrations of atrazine in the Willamette River were associated with the spring application and fall runoff periods. Both historical and current water-temperature data from the lower Columbia River Basin showed exceedances of the "special condition" criterion for the State of Washington (20 degrees Celsius) during August. Trend tests using data from 1974 to 1994 showed significant (p < 0.05) upward trends for water temperature at the Columbia River at Warrendale and the Willamette River at Portland. Trend tests showed significant (p < 0.05) downward trends from 1973 to 1994 for three constituents at the Columbia River at Warrendale: phosphorus in unfiltered water, total dissolved solids, and specific conductance.

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Water quality of the lower Columbia River basin; analysis of current and historical water-quality data through 1994
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Water-Resources Investigations Report
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U.S. Geological Survey ; Earth Science Information Center, Open-File Reports Section [distributor],
x, 157 p. :ill., maps ;28 cm.