DARLINGTON — The first round of well water sampling in Grant, Iowa and Lafayette counties as part of the Southwest Wisconsin Groundwater and Geology Study, also known as SWIGG, has been completed, with state geologist Ken Bradbury and federal biologist Joel Stokdyk awaiting results of specific microbe sampling in the found contaminated wells — results that should give them a clearer picture of the sources of their reported widespread contamination.

News broke in January that 42 percent of the wells tested last fall in the tri-county area through the study tested positive for one or more of the following contaminants: coliform, E. coli and nitrates. These initial results have instigated action from elected officials, including Gov. Tony Evers, who proposed spending $75,000 for the SWIGG study and increase funding for the Well Compensation Grant Program. Assembly Speaker Robin Vos also formed a bipartisan Speaker’s Task Force on Water Quality, which includes both members of the state Assembly and Senate.

Bradbury and Stokdyk spoke to attendees at the second annual meeting of the Lafayette Ag Stewardship Alliance on Feb. 28, explaining how the study will help them better understand how many wells are contaminated, what is causing the contamination and if there are risk factors associated with wells that are contaminated. Bradbury and his team at the Wisconsin Geological and Natural History Survey will also develop geological maps of the tri-county area that can be used and referenced after the study is completed.

“Southwest Wisconsin is a very vulnerable landscape with its geology,” Bradbury said. “Geology is important here, along with soil depth, which effects groundwater vulnerability.”

Along with the area’s unique geology, there are a large number of older wells in Wisconsin that are cased above the water table, which could be a cause of contamination and something the SWIGG team continues to study. Bradbury has found more than 900 wells in Grant County alone were constructed in this manner, and if data proves this type of well construction could increase contamination, may result in recommendations for well construction into the future for southwest Wisconsin.

The two-year study began last fall when 301 wells were sampled — 62 in Lafayette County, 117 in Iowa County and 122 in Grant County. Participants were mailed a letter and selected randomly; samples were collected Nov. 9-10 and sent to a lab at UW-Stevens Point for analysis. After lab analysis, results were shared with the participants in December and further testing on a random sampling of wells that tested positive continued, in which researchers tested for host-specific microorganisms that are unique to humans, cows and pigs.

Of those 301 wells tested in Grant, Iowa and Lafayette counties, an average of 34 percent tested positive for coliform and 4 percent tested positive for E. coli. Sixteen percent of the samples tested positive for high nitrate, which is classified as above 10 parts per million.

“The nitrate issue isn’t just Wisconsin; it’s a big deal in the Midwest, and other states are struggling with this as well,” Bradbury said. “We are not alone.”

Although a similar study was recently completed in Kewaunee County, and results there showed significant agricultural-related contamination of nitrate and coliform, Stokdyk was careful to compare the two studies. Results may differ in southwest Wisconsin, he said, and the solutions to address the contamination may differ too.

SWIGG study representatives have mailed out 2,083 letters to qualified participants and are hopeful to get a better participation rate the second go-round of 500 landowners. The second sampling of wells in Grant, Iowa and Lafayette counties is set for early April.

For more information on the SWIGG study, visit https://iowa.extension.wisc.edu/community-development/swigg or reach out to county conservation contacts Lynda Schweikert in Grant County; Katie Abbott in Iowa County; and Terry Loeffelholz in Lafayette County.