LUXEMBURG — Up to 60 percent of sampled wells in a Kewaunee County study contained fecal microbes, many of which are capable of making people and calves sick, a new scientific study has found.
The microorganisms included Cryptosporidium, a parasite that comes from both people and animals. Researchers estimated Crypto in drinking water is likely infecting 140 of the county’s 20,000 residents each year.
More than 200 people gathered last week at the Expo Hall at the Kewaunee County Fairgrounds to hear the latest results of a study into the source of viruses, bacteria and parasites in their private well water, and what, if anything, they can do to protect their health.
Kewaunee County, where cattle outnumber people nearly 5 to 1, has become a focal point in Wisconsin over whether local, state and federal governments adequately protect drinking water from manure from dairy farms, especially in areas of fractured bedrock, which is common in northeastern Wisconsin. The latest results show an even higher percentage of well contamination than earlier rounds of testing, which had found that about one-third of tested wells were polluted.
According to the study, financed in part by the state Department of Natural Resources, the source of the contamination is both bovine and human waste that enters groundwater through cracks in so-called karst or fractured bedrock in Kewaunee County. The DNR began supplying bottled water this spring to local residents whose wells were found to be tainted by manure.
The researchers cautioned that the percentage of wells with microbial contamination may be even higher than their data show, since the 131 targeted wells were sampled only once during the study period, from April 2016 to March 2017.
“It’s my professional opinion, based on 25 years of experience, that if we sampled more than once, (the contamination rate) would creep up to 90 percent,” Mark Borchardt, a microbiologist with the U.S. Department of Agriculture’s Agricultural Research Service, told the crowd.
According to Borchardt’s research, 40 of the 79 tainted wells contained bovine microbes; 29 contained human microbes, and seven had both. The remainder of the contaminated wells had microbes that could have come from either source.
Some area residents were left confused by the results.
“I’m having a hard time wrapping my head around it,” Kewaunee County resident Sandy Winnemueller said. “Obviously we shouldn’t have septic systems if they aren’t working. We haven’t solved a darn thing. This study has just muddied the waters.”
Nancy Utesch, a local beef farmer and member of advocacy group Kewaunee Cares, said she believes the picture is even worse than the data suggest.
“What people really suspect here is that it’s much worse than the last few years of research implicate,” she said. “It’s become an acceptable way of life here. People just know at certain times of the year not to drink the water.”
In an interview before the presentation, researcher Maureen Muldoon said that due to the fast movement of groundwater through the aquifer, water quality can change in a matter of hours. She affirmed that one sample does not adequately reflect well quality.
“Your well can be fine one day, then contaminated, then fine again,” said Muldoon, a geology professor at the UW-Oshkosh. “It’s like, if you wanted to measure the (annual) temperature and you only went out for one day.”
Kewaunee County has 4,896 private wells. The study tested water from 621 of them representing wells with various depths of soil to bedrock. Of those wells, 208 tested high for total coliform or nitrate. From that subset, 131 wells were randomly selected for further testing.
Seventy-nine of those wells were contaminated by a fecal microorganism — either a virus, parasite or bacteria — 62 of which were linked directly to either bovine or human sources. The other microbes could have come from either source, the researchers found.
The parasite Crypto was found in 12 percent of the sampled wells, with rotavirus A turning up in 14 percent. Borchardt noted that the concentration of bovine-specific rotavirus A was extremely high, in the thousands of “bugs per quart” compared to the concentration of human-specific ones. Other pathogens found included E. coli, Salmonella and rotavirus C, the last of which Borchardt said is rarely detected in groundwater.
The sampling found both Cryptosporidium hominis, which is human specific, and also Cryptosporidium parvum, which can transfer back and forth between people and cattle. According to the CDC, symptoms of Cryptosporidiosis can be serious, and can lead to severe or life-threatening illness for people with weakened immune systems.
In Kewaunee County, the scientists estimated that 3.1 percent of private wells providing drinking water for both humans and calves are contaminated with Cryptosporidium parvum. Of the 12,200 people using private wells in the county, a projected 140 people per year are infected, as well as 1,700 calves.
Borchardt said rotavirus C is one of the few gastrointestinal viruses that can go back and forth between humans and bovine. It can cause diarrhea, vomiting, dehydration and possible death.
Soil depth little protection
The researchers’ original hypothesis was that the greater the depth of the soil, the greater the protection from pollution. And while readings at shallow depths under 5 feet exceeded statewide averages for contamination by nitrate, total coliform and E. coli, they also found more contamination than expected in deeper layers, even where soil depths exceeded 20 feet.
“(Contamination) is worst where the soil is shallowest, because that’s where things get in. If you have 80 feet of clay, it will be diluted. If you are in the center of the county with shallow depth to bedrock, you are very vulnerable,” Muldoon said.
“I cannot think of a hydrogeologically worse place than northeast Wisconsin to put a lot of cows,” she added.
The study was done in conjunction with Randy Hunt from the U.S. Geological Survey’s Wisconsin Water Science Center.
DNR policy adviser Russ Rasmussen said the findings will help his agency develop policy, including proposed changes to administrative rules aimed at preventing manure runoff.
“The DNR wants to find out what’s going on to make good policy decisions,” he said after the meeting. “We are working on implementing all the recommendations that apply to us. We are taking this issue very seriously.”