The Iowa Department of Natural Resources is investigating a fish kill near Houghton in Lee County following a reported pesticide rinsate spill. According to the DNR, the agency’s Washington Field Office was notified on Thursday, June 25 of a possible spill near the ChemGro facility in Houghton.
Officials say the rinsate, a diluted mixture of pesticide used during the cleaning of storage tanks or spray equipment, contained an ammonia-based cleaning agent. Investigators determined the material was discharged onto the ground at the co-op before entering a storm drain that flows into a rural creek south of Houghton.
The drainage eventually connects with larger streams. Co-op staff were instructed to flush the drainageway and pump water from the affected area while DNR personnel collected water samples. Investigators reported the creek water appeared white in color and had a noticeable ammonia odor.
When DNR staff returned to the site the following day, they found numerous dead fish, primarily minnows and bullheads, along about three miles of the creek between 130th Street and 140th Street downstream from the spill.
Preliminary field tests detected elevated ammonia levels in the water. Additional samples have been collected for laboratory analysis, including tests for ammonia, biological oxygen demand, and pesticides or herbicides.
The investigation remains ongoing, and the DNR says it will determine whether enforcement action is warranted once the investigation is complete.
To report a release after hours, please call the DNR’s emergency spill line at (515) 725-8694. Quick reporting can help DNR staff identify the cause of an incident. The DNR website has more information about spill reporting requirements.