ANKENY, Iowa (News Nation/WHO)— The Iowa Department of Natural Resources says 800 gallons of milk spoiled during the Derecho power outage on Tuesday was dumped into a storm drain outside a Hy-Vee supermarket in Ankeny and is now flowing into Fourmile Creek.

According to DNR, officers responded to Fourmile Creek Wednesday morning to investigate reports of the water turning white and fish struggling at the surface. Officers traced the white liquid to the storm drain at the Hy-Vee Store located at 410 N. Ankeny Boulevard.

The DNR says the store reported 800 gallons of milk were dumped into the drain. The store lost power for 19 hours this week after the Derecho storm blew through the state, leaving the milk unusable.

No dead fish have been found, but the DNR says as bacteria naturally break down the milk they will use up oxygen and possibly kill wildlife in the water. The DNR is currently working to slow or stop the flow of the milk-contaminated water. One option they are considering is creating a series of dams and then using vacuums to remove it.

The DNR says it is monitoring the cleanup efforts and “will consider appropriate enforcement action”.

“Materials that we think are harmless can actually be very toxic to the environment,” Iowa Department of Natural Resources Supervisor Ted Petersen said in the press release. “When disposing of a liquid into the municipal collection system, it’s important to check with the local wastewater treatment plant or DNR field office prior to disposal.”