MADISON, Wis. — Additional tests show more southwestern Wisconsin wells are contaminated with manure.
Scientists tested 34 private wells in Grant, Iowa and Lafayette counties in mid-August and found 25, or 73%, were contaminated with human or livestock manure.
The wells are a subset of 840 wells sampled in November 2018 and April 2019. About 32% showed evidence of bacterial or nitrate pollution. Researchers have begun testing smaller subsets of those wells to gather more details.
Tests on an initial 35-well subset in April showed 91% were contaminated with human or livestock manure.
Lafayette County officials in November accused media outlets of reporting 91% of the entire region’s wells were contaminated. They threatened to prosecute journalists who reported on the second round of tests without quoting a county news release verbatim but later backed off amid a firestorm of criticism.