The Missouri Department of Natural Resources found that in May this year, Tyson’s pre-treatment plant in Monett received wastewater containing Alimet, a liquid poultry feed supplement from another Tyson operation in Aurora. The waste was pre-treated at the Tyson plant, then discharged to the city’s sewage system. The compound killed the bacteria that process the wastewater effluent in Monett’s plant, causing virtually undiluted ammonia to flow into a nearby river.
The company revealed the investigation earlier this month in its quarterly notice to the US Securities and Exchange Commission.
Missouri’s Attorney General also filed a six-count civil lawsuit against Tyson after the spill, seeking fines, compensation for damage to the stream and reimbursement for the costs of the state's investigation.