GRIMES - Workers discovered a red color in the Grimes wastewater treatment plant when they arrived at 7 a.m. Oct. 1.
They diverted water to a holding or equalization basin, but some of the red discharge had already reached Little Beaver Creek in Polk County.
By 9:30 a.m., the red color had moved downstream to the state Highway 141 bridge. DNR staff did not see any impact on fish or other aquatic animals, but advise people to avoid contact with the creek until the color dissipates.
DNR is looking for the source of the discharge.