FREEDOM - The Wisconsin Department of Natural Resources said a manure spill at a large dairy farm early this week resulted in a "significant fish kill" in Dutchman Creek.

The spill, which occurred at Neighborhood Dairy, affected about 1½ miles of the creek and is almost entirely within the boundaries of the Oneida Nation. The spill has been contained and cleanup efforts are continuing.

Neighborhood Dairy estimated the manure was released late Sunday or early Monday. The spill was reported to the DNR about 11 a.m. Monday.

DNR runoff specialist Ben Uvaas said a full manure pit and a valve malfunction allowed manure to back up and run out of the farm's runoff collection system, flow through a wide grassy swale and enter the creek. The spill then flowed northeast and crossed under Section Line Road and Vans Road.

RELATED: Dairy farm turns manure into compost side hustle

RELATED: Mega-dairy's future in question after ruling

A berm constructed north of Vans Road contained the spill. Uvaas said the farm hired contractors to help with cleanup efforts, which will continue for several days.

The DNR said the spill killed forage fish like bullheads, mud minnows and sticklebacks

"I imagine quite a high percentage of the fish aren't going to make it because of the strength of the manure in that stretch of the creek," Uvaas said.

The volume of the spill is unknown. The DNR said the region's thick clay soil may prevent groundwater contamination.

"Right now, I think we've got it pretty well boxed-in," Uvaas said.

Neighborhood Dairy operates under a Concentrated Animal Feeding Operation permit and has a "pretty clean compliance record over the years," according to Uvaas. The farm has about 950 milking cows.

The DNR sees several similar spills in the region each year, Uvaas said.

Ethan Safran: 920-996-7267, or esafran@postcrescent.com; on Twitter @EthanSafran