manure spreader
May 22, 2018

Water Quality in Wisconsin

 |  By: Jim Dickrell

Underlain by fractured bedrock that allows water to move from the surface to wells hundreds of feet deep, water quality issues in Kewaunee County, Wis., are a case study in emotion, science and politics. Back in 2015, USDA microbiologist Mark Borchardt went so far as to say well contamination in the town of Lincoln was what he would expect to find in a Third World country. And because Kewaunee County has the largest number of Confined Animal Feeding Operations in the state (15 dairy, one beef), many residents immediately blamed large dairies for the well contamination.

The complicating factor is the county also has 4,822 residential septic systems which also release effluent into the soil on a daily basis. Sorting out where the well contamination was coming from was no easy task, until now. Borchardt is finalizing a major study funded by the Wisconsin Department of Natural Resources, the Wisconsin Groundwater Research Advisory Council, USDA’s Agricultural Research Service and the U.S. Geological Survey. Borchardt was able to use DNA typing to identify whether bacteria were coming from human or bovine sources. He reviewed preliminary results of the study at the Professional Dairy Producers of Wisconsin Business Conference on March 15. Final results are expected this summer. The study was massive. Some 317 wells were sampled in November 2015 during groundwater “recharge” following precipitation. Four hundred wells were sampled in July 2016 when no recharge was occurring.

The conclusions: On a countywide basis, 26% to 28% of wells are positive for total coliforms, E. coli and nitrate-N greater than 10 parts per million. At soil depths to bedrock less than 20', contamination rates generally exceed statewide averages. Bacterial contamination of wells is coming from both human and bovine fecal sources. Human fecal sources appear more frequently during periods of no recharge, while bovine sources are more prevalent when manure is applied and ground- water is being recharged. Contaminated wells contain significant pathogens: Salmonella, Enterohemorrhagic E. Coli, Cryptosporidium parvum and rotavirus. Kids, the elderly and calves are at risk, with an estimated 140 people and 1,700 calves infected with Crypto annually. The critically important part is what policy makers will now do with the research findings.

Currently, the Wisconsin DNR is proposing prohibiting spreading any manure on land with less than 2' of top soil. One concern is for small operators, whose entire farm might overlay an area with less than 2' of top soil. That would leave them no land on which to spread manure, says Don Niles, a local dairy farmer who heads up a clean water advocacy group, Peninsula Pride Farms (see sidebar). Application rates then vary with soil depths of 2' to 3', 3' to 5' and 5' to 20'. There are also rules requiring either injection or incorporation after manure application unless the field is no-till or had cover or perennial crops growing at the time of application. These rules would apply not only to Kewaunee County but to areas of cropland underlain by the same Silurian Dolomite bedrock in 15 Wisconsin counties bordering Lake Michigan.

The Wisconsin DNR estimates 1.6 million acres would be affected. The Wisconsin Legislature has yet to weigh in and finalize rules. Final thought: If farmers are expected to curtail manure applications, what will be required of homeowners? Researchers estimate farmers in Kewaunee County apply 700 million gallons of manure annually while rural septic systems discharge about 200 million gallons of effluent each year. Yet, just under half of the fecal contamination found in wells is coming from rural septic systems.

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