This map was created with data from a 2002 study of private wells in the Lower Yakima Valley. The wells shown were contaminated with nitrates, arsenic or bacteria. Nearby dairies -- one possible source of contamination -- are also shown. Other potential sources are failing septic systems, faulty wells and commercial fertilizer.
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For more information:
Nitrate  |   Arsenic  |   Coliform/E.coli  |   How can nitrates be reduced in my water?  |   More information about nitrates  |   Testing for coliform