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Hazardous drinking water found in 42% of southwest Wisconsin wells
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Hazardous drinking water found in 42% of southwest Wisconsin wells

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Researchers plan to determine if manure from dairy or swine operations or faulty septic systems are the main culprit in tainted drinking water in southwest Wisconsin. The first scientific study of drinking water quality there found that four out of 10 wells were contaminated by dangerous bacteria or chemicals.

The first systematic study of well water in southwest Wisconsin found bacterial and chemical contamination at rates as bad as — and possibly worse than — areas targeted by new state water protection rules.

Some 42 percent of 301 randomly selected wells tested in Iowa, Grant and Lafayette counties exceed federal health standards for bacteria that can come from animal or human waste, or for a toxic fertilizer residue.

“I was surprised that it was as high as it is,” said Lynda Schweikert, administrator of Grant County’s conservation, sanitation and zoning department. “Now I’m just interested to see what is causing the contamination.”

A second round of testing involving more wells is planned for the spring, followed by a close evaluation of pathogens in the water to determine if they are the type that probably originated in dairy or swine manure, or from faulty septic systems.

Well tests conducted in November looked for E. coli and coliform, bacteria that signal the possible presence of other bacteria, viruses and parasites that can cause flu-like symptoms such as nausea, vomiting, fever and diarrhea. Symptoms can be mild to severe to life-threatening.

Testing was also done for nitrate, which causes potentially deadly methemoglobinemia, or blue-baby syndrome. A growing body of research links high nitrate consumption to health risks in adults, including thyroid disease and cancer. Nitrate in drinking water usually comes from fertilizer.

About one-quarter of Wisconsin’s population drinks water drawn from over 800,000 private wells.

The state Department of Natural Resources recommends annual well testing. Schweikert said several residents who participated in the study told her it had been a long time since they had done testing.

The three counties agreed to pay for the initial stage of the study.

Gov. Scott Walker in 2018 approved stricter standards for disposal of manure in 15 eastern Wisconsin counties that have vulnerable groundwater. Conservation groups argued similar conditions exist in southwest Wisconsin, but that region isn’t covered by the new standards.

Walker’s DNR declined to participate in the three-county study, said Scott Laeser, water program director for the nonprofit Clean Wisconsin, which helped coordinate funding. A DNR spokesman declined to comment.

Faulty protection

Pollutants on the surface of the land are carried deep into soil by rain and snowmelt. Throughout much of the state, drinking water is drawn from aquifers that are protected from pollutants by underground layers of rock.

But the bedrock is fractured and porous in a broad curving swath that runs under much of the eastern, southern and western sides of the state.

In the east, Kewaunee and Door counties have long had problems with contaminated drinking water. After years of pressure from residents and the federal government, Walker approved the new manure standards.

But the Wisconsin Dairy Business Association fought to narrow the rule, and it was limited to the 15 eastern counties because more was known about the geology and groundwater there.

The regulations aren’t yet being enforced because required technical standards weren’t included in the rule approved in 2018 by the Natural Resources Board and Gov. Scott Walker after two years of work by the DNR.

The technical standards — which are to be written by the state Department of Agriculture, Trade and Consumer Protection — will spell out how farmers will measure the distance from the land’s surface to the bedrock layer covering the aquifer. That distance is a factor in the rule’s limits on the amount of manure that can be spread on the ground.

It’s unlikely the technical standards will be written and approved in less than 18 to 24 months, said Lacey Cochart, director of DATCP’s bureau of land and water.


State geologist Ken Bradbury said enough was known about conditions in the southwest part of the state to justify applying the manure regulations there, too.

One of the objectives of the ongoing study of Iowa, Grant and Lafayette counties is to answer arguments that insufficient research and monitoring have been done, said Bradbury, who is helping lead the study.

Thus far, the initial results confirm what has been found in previous examinations of test results, Bradbury said.

In Kewaunee County, about one-third of tested wells were contaminated.

When variations in geology were taken into account test results indicated there was a 26 percent to 28 percent rate of contamination across Kewaunee County, said Mark Borchardt, a microbiologist with the U.S. Department of Agriculture’s Agricultural Research Service who led an in-depth study of conditions there.

Borchardt is also a leader of the ongoing study in the three southwest counties. He called the new study’s initial findings “eye-opening.”

Farmers are wary of being unfairly blamed for pollution, but many have expressed support for the study, said Katie Abbott, Iowa County’s conservationist.

“No one wants people getting sick from their drinking water,” Abbott said.

It’s possible that faulty septic systems are causing some portion of the contamination, or that wells need to be upgraded.

Before the study is completed in 2020, researchers plan to investigate a variety of factors that could contribute to contamination, Bradbury said.

For example, in the southwest part of the state at least some of the soil is composed of clay, which can slow the downward flow of pollutants. The clay areas need to be better mapped to understand the extent to which they may protect drinking water, Bradbury said.

“The shallow bedrock and thin soils in southwest Wisconsin make this a vulnerable setting from the standpoint of groundwater contamination,” Bradbury said.

“Now that we’re beginning to get some solid data sets we can begin to compare the results to physical parameters such as bedrock depth, soil type, and well construction in order to determine the most important factors controlling well vulnerability,” he said.

[Editor's note: This story has been updated to clarify two items in the sixth paragraph. The original said research links "the malady" to health risks in adults but should have said "high nitrate consumption." Also, while diabetes is one of the risks, the link has not been as well established as thyroid disease and cancer.]


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Steven Verburg is a reporter for the Wisconsin State Journal covering state politics with a focus on science and the environment as well as military and veterans issues.

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