The DNR is investigating a fish kill along about a 10-mile stretch of the Little Maquoketa River starting north of Epworth and running downstream to Durango.
Starting at Gun Club Road, DNR specialists found thousands of dead fish, mostly rough fish and minnows.
A pollutant could not be identified from preliminary field tests and the source of the fish kill has not yet been identified.
DNR staff took water samples for testing and will continue to look for the pollutant source.
MEDIA CONTACT: Brian Jergenson at 563-608-6749 (cell) or 563-927-2640 (office) or Brian.Jergenson@dnr.iowa.gov.