KEWAUNEE, Wis. — One of Wisconsin’s largest dairy farms is suing the Wisconsin Department of Natural Resources over changes to its wastewater permit that require the operators to limit the size of their herd and begin monitoring groundwater in an area where nitrate contamination has occurred.

Kinnard Farms in Kewaunee County said in its complaint that the business will be harmed if it isn’t allowed to expand its herd and will be burdened by the cost of a groundwater monitoring system.

Farm operators say the monitoring system will cost tens of thousands of dollars initially, plus the fees indefinitely paid to experts to sample, analyze and interpret data from the wells.

The Kinnard operation includes 16 industrial farms with about 8,000 cows. It has struggled with agricultural pollution for years as contaminants began showing up in private wells.

The permit changes are seen as a big win for area residents, who said they felt like it was the first time the DNR had listened to their concerns about their water in public hearings and submitted testimony.

“Kewaunee County residents have been suffering from groundwater contamination, caused by massive amounts of cow manure, for many years. Given Kinnard Farms’ track record, we are not surprised they would challenge basic measures that are necessary to protect their neighbors’ drinking water,” said Peg Sheaffer, spokeswoman for Midwest Environmental Advocates.

Kinnard Farms is required to submit a plan for monitoring the groundwater by May 25. After the plan is approved, the farm would be responsible for installing the wells and monitoring the water for contaminants such as nitrogen, ammonia, nitrates, potassium and E. coli.