The Minnesota Court of Appeals on Monday ordered the state's pollution regulators to reconsider a permit they approved for a mega-dairy farm in southeastern Minnesota, saying they failed to consider the effects of greenhouse gas emissions from the huge milking operation.

The judges reversed the permit, calling the Minnesota Pollution Control Agency's (MPCA) decision not to conduct a full environmental review of the dairy expansion "arbitrary and capricious."

It's an unusual move, both sides agree, and one that raises the possibility that the state could start considering climate change effects as they permit large feedlots.

The project at issue is Daley Farms of Lewiston, in Winona County. The Daley family has been fighting to expand their operation from 1,500 to 3,000 cows, or about 6,000 animal units. That's very large for Minnesota.

The environmental groups that filed the appeal lauded the win.

The MPCA has failed to conduct full environmental impact reviews of huge feedlots, they said, despite years of protest. The expanded Daley Farms would create more than 46 million gallons of manure each year, twice as much waste as the city of Rochester, they said in a statement.

Feedlots — where animals emit gas and large stockpiles of manure decompose — generate significant greenhouse gas emissions such as methane and nitrous oxide. Daley Farms would generate so much methane, the environmental groups argued in their appeal, that it would be the 43rd-largest greenhouse gas emitter in the state.

"Mega-dairies and factory farms in Minnesota are significant contributors to greenhouse gas pollution, and we're glad the Court of Appeals is forcing the MPCA to study the impact of this pollution," Amelia Vohs, a lawyer for the Minnesota Center for Environmental Advocacy, said in the statement.

The Daley family is suing Winona County for denying them the variance they needed, arguing that the county failed to grant them due process because the panel was biased. Winona County limits feedlots to 1,500 animal units. It's one of the few counties in the state with a blanket cap.

In an interview, Bobby King, a director at the Land Stewardship Project, called the appellate court decision "an embarrassment" for the MPCA.

"Whenever the court orders an agency to do its job, to service the people of Minnesota, that is good news," King said.

The MPCA did not respond in time for this story.

Matthew Berger, a lawyer for the Daley family, said the decision was somewhat surprising. But he downplayed the significance, saying the judges did not necessarily require the MPCA to change its practices. It just requires them "to look and make a decision and explain their decision," said Berger.

"I see it as more of a procedural, minor issue," Berger said.

He said they haven't decided whether to ask the state Supreme Court to take the case.

Meanwhile, the family's fight in Winona County continues. In an interview, Ben Daley said the farm is a family business that they want to be able to pass on to the next generation.

"I am a fifth-generation dairy farmer," Daley said. "My nieces and nephews that went to school and came back love farming; they want to continue this family business and maybe give it to their children."

Jennifer Bjorhus • 612-673-4683