The Iowa Department of Natural Resources is investigating a large fish kill in northeast Iowa.
The DNR says the fish kill was first identified in Crane Creek in Bremer County near the town of Readlyn.
A news release says the creek has been significantly impacted, with dead fish being seen nearly 20 miles downstream, near Dunkerton in Black Hawk County.
The DNR gives an intersection near Readlyn where the problem may have originated but did not identify the source.
Agency officials say downstream water users should avoid using water from Crane Creek.