A survey of wells in the vicinity of the flooding Wapsipinicon River finds amajority are contaminated. Linn County Sanitarian Tom Hart and his stafftested private drinking water wells in the area on Thursday and Friday.Hart says for the next four weeks, residents in the flooded areas who use aprivate well for their water should boil that water for at least 10 minutesbefore using it.Hart says people may contact their local health department for a test oftheir well. Hart says water well contamination can occur even in areaswhich didn’t see surface flooding. About one-third of the residents of LinnCounty depend upon a private well for their drinking water.