Manure runoff near Decorah kills 126,000 fish

Manure-laden runoff from a dairy farm killed more than 100,000 small fish in a creek in March near Decorah, according to the Iowa Department of Natural Resources.

Two people reported the manure runoff March 10, and the Iowa DNR traced it to Dale Humpal Dairy, about 7 miles southwest of Decorah. It has about 400 cattle.

Rainfall and snowmelt is believed to have washed manure from open lots at the site through a field and into a tile intake that goes to Dry Run Creek, said Brett Meyers, an environmental specialist for the Iowa DNR, who investigated the incident.

"We assume it was probably from that weekend," Meyers said. "But we don't really have a good way to estimate how much was discharged because it was a continuous flow — a small flow over a long period of time."

The department's investigation found dead fish in a stretch of about 10 miles of the creek, which was tainted with ammonia concentrations from manure that were toxic to aquatic life. The runoff at the dairy wasn't visibly contaminated by manure, Meyers said, but an investigative report noted areas of the creek that were covered with ice that had manure and fish stranded on their surfaces.

Iowa DNR officers "visually observed fish gasping for air on ice," one report said.

Meyers said Humpal was unaware of the contamination before the department's investigation. Humpal had constructed dams on parts of the site to prevent runoff from leaving the property.

Humpal did not immediately respond to a request to comment for this article.

The department's fish kill investigation estimated that about 126,000 small fish perished, including chubs, darters, minnows, shiners, stonerollers and suckers.

It is among the largest fish kills in Iowa documented by the Iowa DNR, based on the number of dead fish.

Insecticides are suspected of killing about 40,000 fish in a 20-mile stretch of Crane Creek in Bremer County last year. But also last year in southwest Iowa, a massive fertilizer spill at a farm cooperative killed more than 750,000 fish in a 60-mile stretch of the East Nishnabotna River.

The value of the fish in the kill near Decorah — for which the state can seek compensation from those responsible for killing them — was about $31,000. The department can also impose an additional fine of up to $10,000.

It's unclear when the department might issue the penalties.

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