Iowa fertilizer spill in Montgomery County killed more than 749,000 fish

RED OAK, Iowa  – The Iowa Department of Natural Resources (DNR) announced on Thursday that the fertilizer spill near Red Oak in Montgomery County, Iowa, earlier this month killed nearly all the fish in an almost 50-mile stretch of the East Nishnabotna River to the Missouri border. 

On March 11, NEW Cooperative, Inc. in Red Oak notified the Iowa DNR of a release occurring on-site. Approximately 1,500 tons (265,000 gallons) of liquid nitrogen fertilizer (32% solution) discharged into a drainage ditch, then into the East Nishnabotna River. The DNR said the release occurred due to an aboveground storage tank valve left open for the weekend. 

Upon learning of the release, DNR staff from the Environmental Field Office worked with the NEW Cooperative staff to stop the release and began cleanup efforts. DNR Fisheries staff began investigating the impacts to the Nishnabotna River. 

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DNR Fisheries staff documented the fish kill occurring in all 49.8 miles of the East Nishnabotna and Nishnabotna Rivers downstream of the spill. The kill continued in Missouri’s portion of the Nishnabotna River and ended near the confluence with the Missouri River.

DNR Fisheries staff used methods outlined in American Fisheries Society, Special Publication 35, and 571 Iowa Administrative Code Chapter 113 to evaluate the extent of the fish kill and estimate the number of dead fish. The rules and the use of the American Fisheries Society’s methodology are authorized by Iowa Code section 481A.151.

Cleanup efforts at the NEW Cooperative facility are ongoing. Contaminated soils continue to be removed from the facility and from around a levee west of the facility. The contaminated soils will be land applied at approved locations, at agronomic rates consistent with Iowa law.

Additionally, NEW Cooperative is pumping water from the east side of the levee. The pumped water will be stored in on-site holding tanks until land application can occur. A third-party consultant is collecting samples of the water-fertilizer mixture to determine accurate land application rates. 

Per Iowa Code section 455B.186, a pollutant cannot be discharged into a river without a permit. The DNR said in Thursday’s release that agency field staff are working with the DNR’s Legal Services Bureau to determine next steps with regards to enforcement action and restitution for lost aquatic life. The DNR will continue to monitor cleanup efforts.

Field test results indicate ammonia levels are declining in the river. The DNR continues to advise people to avoid recreating on the river and collecting and/or eating dead fish found on or near the river.