The nitrate contamination of private well water in Iowa.
The State-Wide Rural Well-Water Survey was conducted between April 1988 and June 1989. About 18% of Iowa's private, rural drinking-water wells contain nitrate above the recommended health advisory level (levels of NO3-N greater than 10 mg/L); 37% of the wells have levels greater than 3 mg/L, typically considered indicative of anthropogenic pollution. Thirty-five percent of wells less than 15 m deep exceed the health advisory level, and the mean concentration of nitrate-nitrogen for these wells exceeds 10 mg/L. Depth of well is the best predictor of well-water contamination. Individually, NO3-N levels of more than 10 mg/L occurred alone in about 4% of the private wells statewide; pesticides were present alone in about 5%. Total coliform positives occurred alone at 27% of the sites. In a cumulative sense, these three contaminants were detected in nearly 55% of rural private water supplies.
Kross
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Department of Preventive Medicine and Environmental Health, AMRF-Oakdale Campus, University of Iowa, Iowa City 52242.
Hallberg
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Bruner
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DR
Cherryholmes
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Johnson
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JK
D004755:Enterobacteriaceae / Q000302:isolation & purification; D007484:Iowa; D009566:Nitrates / Q000032:analysis*; D010575:Pesticides / Q000032:analysis; D012423:Rural Health; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
D009566:Nitrates; D010575:Pesticides; D014874:Water Pollutants, Chemical