DES MOINES - The DNR is investigating fish kills in Ida, Clay and Lyon counties on Thursday.
Ammonia levels in Odebolt Creek, near Arthur in Ida County, ranged from 7.5 to 10 parts per million (ppm). Ammonia levels from 3 to 5 ppm, depending on conditions, can be toxic to fish and other aquatic life. The DNR observed a small number of dead minnows and chubs, and estimated the kill happened Tuesday or Wednesday.
Investigators at Willow Creek, near Royal in Clay County, are working to identify a possible source of pollution that caused the fish kill there. Investigators found ammonia levels at 15 ppm and very low dissolved oxygen levels, in addition to a strong manure smell. The kill affected bullheads, chubs and minnows in the creek.
The DNR is also starting an investigation of a fish kill on Mud Creek near Alvord in Lyon County.
Recent heavy rains likely washed manure into many northwest Iowa streams with low flow conditions. With these conditions, dissolved oxygen levels are also low. When manure decomposes in a stream, it releases ammonia and uses up available oxygen in the water, suffocating fish.
"With the weather and current conditions, it's likely that these are not the only fish kills in northwest Iowa," said Ken Hessenius, supervisor of the DNR's Spencer field office. "That's why it's so important for producers to take precautions with their manure and for people to report fish kills right away when they see them."
Reporting a fish kill or manure release as soon as you discover it can help the DNR respond quickly and work to reduce the impact on water. Fish kills and spills can be reported to your local DNR field office within normal business hours. Outside of normal business hours, report fish kills and spills to the DNR's 24-hour spill hotline at (515) 281-8694. DNR field offices include: Manchester: (563) 927-2640, Mason City: (641) 424-4073, Spencer: (712) 262-4177, Atlantic: (712) 243-1934, Des Moines: (515) 725-0268, Washington: (319) 653-2135.
Anyone with information regarding any of the fish kills should contact the DNR Spencer field office at (712) 262-4177.