Groundwater study in southwest Wisconsin reveals contamination

Results from the first round of groundwater sampling in Grant, Iowa and Lafayette Counties show contamination by nitrate and coliform bacteria.

In a release sent by the Wisconsin Geological and Natural History Survey, results of random samples from 301 private wells were released on Wednesday.

Overall, 42 percent of the wells tested were considered unsafe. Thirty-four percent of the samples were positive for total coliform and four percent were positive for E. Coli. The presence of either bacteria at any level in drinking water is considered unsafe according to state well codes.

Sixteen percent of the samples exceeded the health standards of 10 parts 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.

Ken Bradbury, a geologist leading the study, was not surprised by the results. He said southwestern Wisconsin is an area where groundwater can be easily contaminated.

Bradbury said the best way for people to avoid contamination is to make sure their 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," he said. "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."

The three counties led the push to have a groundwater study done, said Terry Loeffelholz, the Conservation and Zoning Administrator for Lafayette County. He said the results released Wednesday are preliminary, and he is waiting to draw conclusions until more results are available.

Loeffelholz said he hopes the study will show 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 release from the Wisconsin Geological and Natural History Survey said the cause and source of the contamination are not yet known and will be the focus of additional sampling and study in 2019.

The two-year study will collect a second set of samples in the spring and then will evaluate factors that contribute to groundwater contamination.

"I think it’s high time that we paid more attention to the groundwater quality in southwestern Wisconsin because it’s an important part of the state and you know, it’s a human health issue and there’s really nothing more important than clean groundwater, clean drinking water for everybody, and so understanding what the water quality is and how we can make it better is pretty important," Bradbury said.