MADISON, Wis. (AP) — The state Department of Natural Resource is helping local government workers clean up after a fire flooded a dairy plant with butter.

The fire broke out in a butter storage room at the Associated Milk Producers, Inc., facility in Portage around 9 p.m. on Monday, the Wisconsin State Journal reported. The butter heated up and flowed through the building, impeding access. Firefighters needed several hours to extinguish the blaze.

Most of the butter that escaped the plant flowed into the sewers and traveled to a wastewater treatment plant, DNR officials said Thursday. Plant personnel have been clearing butter out of their equipment since the fire but the facility is still operating effectively, agency officials said.

About 20 gallons of butter flowed into the storm sewers and into a nearby canal, DNR officials said. Booms were deployed to contain the butter and it’s since been removed, they said.

The incident’s overall environmental impact appears to be minimal, they said. An investigation is ongoing.