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DNR Investigates "Orange Water" and Fish Kill in Cheslea Creek in Mason City
Posted: 08/10/2012
MASON CITY – A discharge of iron-laden cooling water and resulting fish kill is being investigated by the Iowa Department of Natural Resources (DNR) on Cheslea Creek on the south side of Mason City.

The DNR responded to a report Thursday morning that water in Cheslea Creek was orange. The orange discharge was traced back to a tile outfall where the Golden Grain Energy facility is allowed to release cooling water from the process.

A final fish count by DNR fisheries biologists was not available yet on Friday afternoon. The fish killed were smaller, minnow species and no sport fish were found. There were also portions of the stream where accurate fish counts could not be obtained because the water was so discolored.

The Golden Grain facility is located approximately one-and-a-half miles south of Mason City. Cheslea Creek flows north toward the city, through Lester Milligan Park and eventually to the Winnebago River. About a mile of Cheslea Creek was affected and it did not reach Big Black Lake in Lester Milligan Park.

Upon further investigation by DNR environmental specialists, it was discovered that excess sulfuric acid had been added to the cooling water system that mobilized rust within the plant piping system, which then resulted in an orange discharge into Cheslea Creek.  

The affected cooling tower was taken off line and approximately 600,000 gallons of the iron-laden water diverted to a storm water pond that Golden Grain has on site. The pond discharge pipe is closed and the pond is very nearly empty due to the drought conditions. The water will be stored there and then processed back through the plant with no expected discharge.

The DNR is currently waiting for water samples to be analyzed and will consider appropriate enforcement actions once the data has been received.  In addition, restitution may be sought for the dead fish.