The full power of Minnesota’s agricultural industry will line up against state pollution regulators in a Ramsey County court on Wednesday, in an unexpectedly heated conflict over how much time the public will have to comment on a major expansion of a dairy megafarm in Winona County.

Eight of the state’s leading agricultural groups filed suit against the Minnesota Pollution Control Agency (MPCA), arguing that the agency lacks authority to add two weeks to a 30-day public comment period outlined in state law.

At issue is the expansion of Daley Farms of Lewiston, from 1,728 dairy cows to 4,680, in an area of the state which is already experiencing significant drinking-water contamination from agriculture. In Utica Township, where the dairy is located, some 46 percent of private wells tested higher than the legal limit for nitrate, which primarily comes from fertilizer and manure.

The Daley proposal is just one of many new or expanding large animal operations generating conflicts in communities throughout southeast Minnesota. The MPCA is weighing whether to take the unusual step of conducting major environmental reviews on two proposed animal operations, one in Fillmore County and another in Wabasha County.

In Winona County, the Daley proposal has generated intense public interest on both sides of the question. The business is already operating above the size allowed by county regulations, but it was grandfathered in when the county changed its ordinance.

Earlier this year, it applied for a state permit to expand, and the MPCA opened a 30-day public comment period on Oct. 1. A public hearing on Oct. 16 drew a crowd that included supporters and opponents. After receiving requests from the public, the MPCA agreed to extend the comment period to Nov. 15, despite the objections of Daley Farms.

On Friday the agricultural groups, including the Minnesota Farm Bureau, the Minnesota Pork Producers and others, filed suit. Daley Farms is not one of the plaintiffs.

“The issue has nothing to do with Daley per se,” said Gene Hugoson, interim director of the Minnesota AgriGrowth Council, a major industry group. “It’s about whether or not the MPCA has the authority to arbitrarily change the law in terms of the number of days to comment.”

The MPCA said in a legal document filed Tuesday that it does have legal authority to extend the comment period, and an agency spokesman said it has done so before. In this case, the agency said, it had received more comments than usual, and that many people called asking for an extension because local farmers were too busy with the harvest. The agency also said the Daley proposal would more than double what is already the largest feedlot in the county, and it wanted to be sure that the community had the chance for meaningful engagement.

That’s exactly what the farm groups are trying to prevent, said Bobby King, policy director for the Land Stewardship Project, a conservation and family farm group that has been involved in the fight. “They don’t want more opportunity for local farmers and residents to understand what’s being proposed,” he said.

The Daley proposal includes thousands of documents and significant potential impacts around the community, King said. It calls for two new wells that would each draw 30 million gallons of water per year, bringing the total used by the farm to 92 million gallons per year. Manure would be spread in areas near municipal drinking water systems that are already high in nitrate, and where karst geology and sinkholes pull contaminants directly from surface fields into the aquifer. And there are already 13 feedlots within a 3-mile radius.

At the hearing scheduled for Wednesday, a Ramsey County judge will consider the agricultural groups’ request for an injunction that would immediately end the public comment period.

Matthew Berger, an attorney who represents the groups in the lawsuit and Daley Farms in its proposed expansion, said extending the public comment period for another two weeks will imperil the success of the project. Though he declined to provide specifics, he said that, “with rising interest rates and circumstances in the agricultural economy in general, it’s vital they get the approvals they need in timely fashion.”

Hugoson said the case involves a larger principle for the industry.

“If you can extend it 15 days this time, what’s to prevent 60 days or two years,” he said. “We need some certainty here.”

The state permit is not the only regulatory hurdle Daley Farms has to clear. It must also win a variance from a county ordinance that restricts the size of feedlots, and it must get a conditional use permit as well.