COLLINS – A fish kill along Wolf Creek in Jasper County has been traced to high ammonia levels flowing out of an underground tile line about one mile southwest of Collins in Story County.
The most likely source of ammonia is fertilizer, manure or other sources like a cleaning product or industrial byproduct.
“We don’t know exactly where or how it got into the tile line. It could have been through a storm drain in town or a tile inlet in the country,” said Bill Gibbons, environmental specialist at the DNR’s Des Moines area field office.
“This is a good reminder that tile inlets and storm drains along the street carry water and pollutants directly to a nearby stream,” he said. “People need to take care and dispose of unused chemicals and fertilizer properly.”
The fish kill spanned more than nine miles of Wolf Creek starting near Collins and running south to Jasper County. More than 66,500 fish died, mostly minnows, shiners, stonerollers and chubs. Some bullheads, sunfish, and smallmouth and largemouth bass were also killed.
A farmer reported the fish kill Sept. 3 after discovering dead fish on his property. When Gibbons investigated Saturday he found elevated levels of ammonia and dead fish below where a county tile line empties into Wolf Creek, while live minnows swam above the area.
Gibbons visited with livestock facilities and a local co-op, but found no evidence of spills. Crops haven’t been harvested yet, so farmers haven’t started applying fertilizer or manure.
Lab results from water samples collected on Sept. 3 show ammonia nitrogen levels that are toxic to fish – 9.9 and 40 milligrams per liter – below the tile outlet.
The DNR is still seeking the responsible person. Anyone having information can call the DNR’s Windsor Heights field office at 515-725-0268. Report spills and fish kills to the DNR’s 24-hour spill line at 515-725-8694.
DNR fisheries staff determined the value of the fish killed was $7,082.19 and the cost of the fisheries investigation at $939.67.