DNR Revisions for Manure Spreading Take Effect July 1

MADISON - New rule revisions designed to reduce manure groundwater contamination, specifically in the northeast section of the state, take effect July 1.

The changes, under the Wisconsin Department of Natural Resources' ch. NR 151, Wis. Adm. Code, relate to Silurian bedrock, which are areas where the soil depth to bedrock is shallow and the bedrock may be fractured.

"The main purpose of this targeted performance standards is to reduce the risk for contamination in groundwater from manure applications on shallow bedrock soils," said Mary Anne Lowndes, DNR Watershed Management Section chief.

Lowndes said Silurian bedrock soils identified in the rule revisions are dolomite bedrock with a depth of 20 feet or less. The rule targets an area in the state that may include portions of Brown, Calumet, Dodge, Door, Fond du Lac, Kenosha, Kewaunee, Manitowoc, Milwaukee, Ozaukee, Racine, Sheboygan, Walworth, Washington, and Waukesha counties.

"Within a specified area, the rule sets forth manure spreading rates and practices that vary according to the soil depth and texture," said Lowndes. "For Silurian bedrock, the most restrictive practices apply to those limited areas with the highest risk for pathogen delivery, zero to five feet in depth, and less restrictive requirements apply in areas with five to 20 feet to bedrock."

Lowndes added that Concentrated Animal Feeding Operations (CAFOs) in the Silurian bedrock areas will be required to comply with the standards in the new rule, when it is incorporated into their permit under the Wisconsin Pollution Discharge Elimination System (WPDES), and a cross reference to the targeted performance standard language has also been added to ch. NR 243, Wis. Adm. Code., which applies to CAFOs subject to WPDES permitting. Non-permitted farms in Silurian bedrock areas will also be required to comply with the standards in the rule.

Lowndes added the DNR has worked with the University of Wisconsin Department of Soil Science to offer a Silurian bedrock map(exit DNR) tool that can be used to identify areas where the bedrock soil depth is less than 20 feet, and that the department is working with the Department of Agriculture, Trade, and Consumer Protection and county land conservation departments on how best to implement the new rules.

The new rule is based on a long-term effort by the department to seek public input on changes to NR 151, including conducting studies, public meetings and hearings and hosting a technical advisory committee and Groundwater Collaboration Workgroup that met between 2015-2017.