By MaryBeth Matzek
Research shows that human and bovine waste is finding its way into wells in Kewaunee County.
Dr. Mark Borchardt, a microbiologist with the U.S. Department of Agriculture, shared those findings during a presentation earlier this year at the 2017 Midwest Manure Summit in Green Bay. In a study funded by the Department of Natural Resources, Borchardt and his team used DNA sequencing to identify bacteria and pathogens in different Kewaunee County wells to determine if they came from cows or people.
The county has been ground zero in Wisconsin in the battle between some residents and large-scale farmers. In 2014, six environmental groups petitioned the U.S. Environmental Protection Agency to investigate groundwater contamination in the county. The DNR then brought together farmers, neighbors, environmental groups and government officials to find strategies to reduce groundwater pollution risk.
“There has been a lot of finger pointing and politics going on regarding water in Kewaunee County so we took a closer look at this issue to determine the source of the pollution,” Borchardt said. “The evidence shows both people and cows are contaminating the groundwater in Kewaunee County.”
Borchardt said three factors play a role in the problem: the county’s high animal population (it is home to 16 CAFOs), the presence of more than 4,700 septic systems and the area’s fractured karst bedrock, which means liquids on the surface can find their way quickly to the groundwater below.
“Septic systems, by their very nature, are designed to release effluent underground,” he said. “There’s a lot of septic systems in Kewaunee County and they’re holding a lot of waste.”
Borchardt designed a study to randomly sample wells that accounted for differences in the depth to bedrock and looked for bacteria at different times of the year, including “recharge” events, such as heavy rains or when the melting snow increases the amount of surface water.
In 2016, Borchardt’s team sampled water during three time periods and found contamination linked to sanitary septic systems during dry periods, such as the summer. During wet conditions, contamination was linked to cows.
A closer look at the study results:
• April: 11 cases of contamination linked to human sources and five cases linked to cows.
• July: Six cases tied to humans and five cases linked to cows.
• November: 16 cases linked to cows and one from humans. The samples were taken after a heavy rain event.
Based on those results, Borchardt hypothesized the county’s septic systems provide a continuous contamination source throughout the year but waste from cows is entering the groundwater after recharge events.
“This study is ongoing, but the data we have is sound. Our interpretation of the data may change over time, but this is where we are at now,” he said. “I think farmers and county residents recognize they bear some responsibility. I might be naïve, but I am hoping both parties can contribute to a solution.”