The Iowa Department of Natural Resources says elevated chlorine levels from the city swimming pool were probably the cause of a small fish kill in the city of Cherokee.
On Wednesday, the DNR investigated a report of dead fish found Tuesday night in Railroad Creek.
The city reported that a valve on the chlorine tank was left on, resulting in chlorine reaching the stream through runoff into the storm sewer.
Ken Hessenius of the DNR's field office in Spencer said pool owners should make sure that runoff or drained water goes into a sanitary sewer or be neutralized. Hessenius said the chlorine levels contained in swimming pools can be toxic to aquatic life.