SHELDON, IOWA (KELO.com) -- On Saturday, Iowa DNR officials were informed of a fish kill on the North Fork of the Floyd River about seven miles northeast of Sheldon in O'Brien County.
The next day dead fish were found near the North Fork and the Floyd River and continuing about four miles downstream.
DNR specialists have not yet identified the pollutant source saying recent rainfall likely diluted the pollutant.
The investigation is ongoing.
