Groundwater sampling results in three Wisconsin counties show contamination by nitrate and coliform bacteria. According to WMTV, results of samples from 301 private wells in Grant, Iowa and Lafayette Counties were released by the Wisconsin Geological and Natural History Survey.
According to WMTV, 42% of the wells tested were considered unsafe overall. 34% of the samples were positive for total coliform and 4% were positive for E. Coli. According to state well codes, the presence of either bacteria at any level in drinking water is considered unsafe.
According to WMTV, 16% of the samples exceeded the health standards of 10 part per million for nitrate-nitrogen. High nitrate levels in drinking water have been associated with blue baby syndrome, colorectal cancer, thyroid disease and central nervous system birth defects, according to WMTV.
The geologist leading the study, Ken Bradbury, was not surprised by the results. According to Bradbury, southwestern Wisconsin is an area where groundwater can be easily contaminated and the best way to avoid contamination is to make sure wells are in good shape and to test them regularly.
"The thing to know is when you have a private well, there’s nobody else that’s paying attention to it, it’s not like if you live here in Madison where there’s a water utility that’s testing the water," Bradbury said to WMTV. "You’re on your own if you have a well. So it’s up to the homeowner to do the testing themselves and so we do recommend once a year."
According to Terry Leffelholz, the Conservation and Zoning Administrator for Lafayette County, the results are preliminary and he is waiting to draw conclusions when more results are available. He hopes the study shows whether the counties have a groundwater problem, what the problem is and whether the Department of Natural Resources well code is appropriate for this region of the state.
The Wisconsin Geological and Natural History Survey release said the cause and source of the contamination are not known and will be the focus of additional sampling in 2019. According to the release, the study will collect a second set of samples and then evaluate factors that contribute to groundwater contamination.