EAU CLAIRE — Interest in water quality continues to grow as more and more people want to know what is coming out of their tap.

Proving that point, Mark Borchardt, a microbiologist with the U.S. Department of Agriculture’s Agricultural Research Service, was “thrilled” with the turn-out at a “What’s in Your Water?” event held Dec. 4 in Eau Claire.

In conjunction with other researchers, Borchardt has examined private well contamination in Kewaunee County extensively and continues to be a part of the Southwest Wisconsin Groundwater and Geology study in Iowa, Grant and Lafayette counties.

Much of the research has focused on tracking the source of fecal contamination, from humans and livestock, in private wells in addition to nitrate contamination. According to Borchardt, the fecal contamination portion of the research is more unique than the nitrate contamination, but both have the potential to be hazardous to human health.

Private well contamination is a contentious issue, often pitting the exurban community, who blames bovine waste for contamination, against agriculture, who blames an increased number of septic tanks, to the point where neither side trusts the other’s data, Borchardt said.

He commented on the relatively relaxed atmosphere at the Eau Claire meeting, away from the study locations, comparing it to divided and intense meetings he’s presented at with the locally affected populations, who tend to demonstrate the significant exurban/agriculture division.

However, of the 138 samples in Kewaunee County taken from 131 household wells previously known to have been contaminated, the “scoreboard” between those with bovine and human fecal contamination was nearly equal, Borchardt said. As the populations of cows and people grow in that area, the math was simple.

“More cows plus more people equals more fecal waste,” Borchardt said.

In addition to the bovine and human contamination, the SWIGG study has looked at swine contamination as well. Nonspecific sources were also tracked.

Being able to determine the sources of the fecal contamination, Borchardt said, is thanks to microbial source tracking, which has come a long ways in the past 20 years.

Earlier this year, 32 of 35 wells known to have been contaminated previously tested positive for contaminants in the first phase of the SWIGG study.

Results announced in a press release Monday, Dec. 2, showed “very similar” data to the prior round’s results, Borchardt said.

High levels of nitrate contamination were also found in the studies, and Borchardt reported that the Wisconsin Department of Agriculture, Trade and Consumer Protection found that 200 million pounds of excess nitrogen had been applied to agriculture fields.

Beyond the contaminant sources themselves, additional factors in the well pollution included depth to bedrock and the nature of the fractured bedrock environment that supplies water in the study areas.

Borchardt also discussed correlative data collected during the course of research. He reminded audience members that the data does not demonstrate cause and effect, just correlation.

Agricultural risk factors, such as the area of ag fields nearby and distance from manure lagoons, were more correlative to contaminants than septic system risk factors. A positive correlation between higher ag risk factors and higher risk of contamination was generally shown.

The correlation between the factors doesn’t necessarily mean causation. For example, Borchardt said, manure lagoons themselves may not be a culprit; another seemingly just as logical explanation could be nearby application of the manure contained in the lagoon.

Getting clean water into the homes can be complicated. Borchardt, citing an example, noted that just because a well meets code and would seem to be sufficiently deep doesn’t mean it’s protected from problems.

“You can’t construct your way out of it,” Borchardt said, adding that land use is more relevant than well construction.

Reverse osmosis systems can eliminate contamination and are nice, Borchardt said, with the caveat that they must be regularly maintained in order to be effective.

The private well studies focused on the parts of Wisconsin — primarily the southwest and east — with the fractured bedrock environment.

Areas with a more porous media for water to flow down through filter the water differently than the fractured bedrock does.

While Borchardt’s research is focused on private wells, primarily in rural areas, he did take time to address an audience member’s questions about the safety of city water as well.

Cities that use surface water, which must be disinfected, see much lower risk of illness among residents than cities that draw groundwater, which is not required to be disinfected, Borchardt said.

As of 2010, Wisconsin has a statute that prohibits the requirement to disinfect groundwater, Borchardt said.

Illness tied to water does still occur where disinfected surface water was used by the city, he said, but that likely occurs as a result of old distribution systems delivering the water or inadequate disinfection.

A well water quality viewer of private well data in Wisconsin can be accessed at https://tinyurl.com/y8n24qpn.