Water-quality data identify surface-water-quality problems in Bear Creek basin, Jackson County, Oreg., where possible, their causes or sources. Irrigation and return-flow data show pastures are sources of fecal coliform and fecal streptococci bacteria and sinks for suspended sediment and nitrite-plus-nitrate nitrogen. Bear Creek and its tributaries have dissolved oxygen and pH values that do not meet State standards. Forty to 50% of the fecal coliform and fecal streptococci concentrations were higher than 1,000 bacteria colonies per 100 milliliters during the irrigation season in the lower two-thirds of the basin. During the irrigation season, suspended-sediment concentrations, average 35 milligrams per liter, were double those for the nonirrigation season. The Ashland sewage-treatment plant is a major source of nitrite plus nitrate, ammonia, and Kjeldahl nitrogen, and orthophosphate in Bear Creek. (USGS)
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USGS Numbered Series
Water quality of Bear Creek basin, Jackson County, Oregon
U.S. Geological Survey,
viii, 130 p. ill., maps (1 fold. in pocket) ;27 cm.