PIERRE, S.D. –  The South Dakota Dept. of Environment and Natural Resources (DENR) is investigating ammonia concentrations in the discharge from a Smithfield Foods wastewater treatment plant in Sioux Falls, South Dakota, where the company operates a pork production facility.

Smithfield reported on Aug. 15 that the wastewater treatment plant “had an upset” and that the ammonia concentrations in the discharge were higher than the regulatory limits in the company’s surface water discharge permit, the DENR said. The ammonia levels present no risks to human health but do pose a threat to fish.

In a statement, Smithfield said the company has corrected the problem.

“Smithfield Foods Inc. has corrected wastewater treatment operations at the company’s facility in Sioux Falls and is back within the regulatory limits of its Surface Water Discharge Permit. Smithfield takes environmental compliance very seriously and strives for 100 percent compliance, 100 percent of the time. There was no risk to human health and no reports of impact to fish or other area wildlife.”

DENR Secretary Steve Pirner said the agency will continue to monitor the situation. The DENR has sent investigators to collect water quality samples. No negative impacts to fish or the Big Sioux River have been observed. The specific cause of the increased ammonia concentrations is under investigation, and Smithfield is taking steps to reduce ammonia concentrations discharging to the Big Sioux.