WASHINGTON – Authorities with the US Environmental Protection Agency has launched a criminal investigation into a chemical spill in Monett, Mo.

The EPA issued a search warrant on Springdale, Arkansas-based Tyson Foods Inc.'s Monett facility searching for documents and records as part of a criminal investigation into the incident that caused a fish kill in Clear Creek.

In May, Tyson received a shipment of wastewater containing Alimet, which is a liquid animal feed supplement, from another company facility in Aurora, Mo. Tyson reportedly sent the wastewater to its pre-treatment facility and later discharged the water to the city of Monett's sewer system. The Missouri Department of Natural Resources (DNR) said the discharge caused operational problems at the city's wastewater treatment facility. Dead fish were discovered along a six-mile stretch of Clear Creek when the Monett Municipal Wastewater Treatment Facility discharged the water into a tributary of Clear Creek.

The DNR cited Tyson with a notice of violation for the fish kill. The agency also cited the city Monett for failing "to operate and maintain facilities to comply with the Missouri Clean Water Law and applicable permit conditions".

Missouri Attorney General Chris Koster also filed a lawsuit against Tyson Foods for "unlawful dumping of untreated industrial wastewater" that led to the fish kill in Clear Creek.