MONETT, Mo. (AP) — State officials are investigating to determine if a massive fish kill and a bad odor that hung over a southwest Missouri town was caused by a chemical from a Tyson Foods plant that disrupted a wastewater treatment plant and fouled a stream.
The Missouri Department of Conservation and the Department of Natural Resources are conducting a joint investigation into the incident, which began May 16 when a chemical compound called Alimet, a feed ingredient, was spilled at Tyson's feed mill in Aurora.
Workers captured most of the chemical but some of it made it into the wastewater treatment plant in Monett, The Monett Times reported.
Skip Schaller, Monett's utilities superintendent, said the chemical killed the bacteria that the wastewater plant used to treat effluent, allowing some contaminated water to flow into Clear Creek.
The bacterial disintegration in the 15 million to 20 million gallons of water in the plant created mostly undiluted ammonia that caused a foul odor around Monett for several days. The smell had mostly dissipated this week, Schaller said, and the wastewater plant in Monett was beginning to operate properly.
The ammonia killed virtually all aquatic life in the stream between Monett and Pierce City, said Adam Borman, who is leading the investigation for the conservation department.
"We're talking about thousands of fish," he told The Joplin Globe.
DNR spokeswoman Gena Terlizzi said the department and the conservation department are conducting a joint investigation.
Tyson Foods spokesman Worth Sparkman said in a statement, "We're working cooperatively with city and state officials as they investigate this matter. We're awaiting additional details so we can understand if our operations played a role in what happened."
According to test results received Wednesday, ammonia levels from tests taken last Friday reached around 20 milligrams per liter. Monett's plant is licensed by the DNR for ammonia of about six milligrams per liter.
Schaller said Wednesday he was confident ammonia levels in the water had dropped to safe levels but daily samples were being taken from the creek to track the progress.
Meanwhile, Schaller said the city will probably face fines for exceeding its wastewater permit limits.
"We're going to review the situation when this is done and definitely try not to let something like this happen again, and how to protect the plant better next time," he said. "If anything, it's proved to me we have to tighten up some of our controls and procedures."