The Wisconsin Department of Natural Resources reports human error is to blame for the release of sewer water into the Wisconsin River last January.
About 6500 pounds of anhydrous milk fat from the Kraft Heinz cheese plant in Wausau drained into the sewer and plugged it up when the material solidified. That led to 3.7 million gallons of sewer water flowing into the river.
The human error involved a valve being set incorrectly during a production run. The cleanup cost the city more than $51,000.
