Officials say about 2,500 gallons of wastewater have spilled from a facility in Fort Dodge, and most of it entered the Des Moines River.
The state Department of Natural Resources says sludge was being transferred Sunday from the facility when the hose on the transfer pump came out of the receiving structure. The incident happened when the transfer pump was left unattended for 10 minutes.
Only about 55 gallons could be recovered because of snow melt and other complications. Most of the remaining sludge entered a nearby intake that discharges directly into the Des Moines River. However, officials say dilution limited the impact to the river.
DNR says it will continue to monitor the situation.