MINNEAPOLIS (AP) — The Minnesota Court of Appeals has ordered state pollution regulators to reconsider their decision to grant a permit for a mega-dairy farm, saying the regulators failed to consider greenhouse gas effects when they decided a farm in southeastern Minnesota could expand its herd.

In a ruling Monday, the judges called the Minnesota Pollution Control Agency’s decision not to conduct a full environmental review of the dairy expansion “arbitrary and capricious.” The Star Tribune reported the ruling raises the possibility that the state could start considering climate change effects when permitting large-scale dairy farms.

Daley Farms of Lewiston had been granted a permit to expand its milking operation from 1,500 to 3,000 cows, which would be considered a large operation in Minnesota.

Environmentalists argued the expansion would create more than 46 million gallons of manure each year, generating so much methane that it would become 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 a statement.