ALLISON, Iowa — The Iowa Department of Natural Resources (IDNR) is investigating a fertilizer spill that occurred July 11 in Allison, Iowa.

According to Trent Lambert, IDNR environmental specialist, an employee of the Farmers Cooperative was pulling a tank of 32 percent liquid nitrogen fertilizer when a seam on the tank ripped open.

"About 800 gallons of the fertilizer spilled on a city street," he said. "Without reporting the spill to the IDNR, employees decided to wash the spilled liquid into a storm sewer.

"The IDNR was notified (on July 12), 26 hours after the spill," he added. "IDNR staff advised the co-op to flush the storm sewer with water and pump up the mix of water and fertilizer, to prevent additional fertilizer from reaching a nearby stream. They were also asked to soak up liquids standing on the street."

But when the IDNR staff arrived that afternoon, they found dead minnows for about one-half mile downstream of the storm sewer.

"Initial water sampling over the eight-mile stretch of stream to the West Fork of Cedar River showed elevated levels of ammonia in spots, but ammonia levels dropped significantly over the next three days," Lambert said. "By Monday afternoon (July 14), no additional dead fish had been found."

On July 12, the IDNR staff initially asked the co-op to build a dam across a drainage ditch south of Allison to collect additional contaminated water. By early Monday afternoon, the co-op had recovered about 42,000 gallons of the water-fertilizer mix.

The IDNR will continue to monitor the cleanup and consider appropriate enforcement actions, Lambert added.