Oklahoma has resolved the decades-long legal battle against six companies over the alleged poultry-litter pollution of the Illinois River Watershed.

Announcing the decision yesterday (13 July), Oklahoma Attorney General Gentner Drummond said it “resolves the case in full”.

The new settlement covers all six of the original defendants – Tyson Foods, Cargill, George's, Peterson Farms, Cal-Maine and Simmons Foods.

The companies will collectively pay about $44m.

The settlement follows the rejection of a “narrower” settlement with four of the six companies, Drummond added.

Under the new agreement, $41.6m will go toward an environmental relief fund, while $1.9m will be used to create an independent compliance auditor.

Another $420,000 in penalties will be paid into the Oklahoma Department of Environmental Quality Revolving Fund.

As part of the deal, the companies have agreed to “progressively” cut the share of poultry litter applied within the watershed over a seven-year period.

During the first two years, no more than 40% of the waste generated in the watershed may be spread on nearby land.

That limit will fall to 30% in the third and fourth years, and then to 20% from the fifth through the seventh years.

The agreement also requires the companies to pay for, or obtain financing for, half of the cost of installing “vegetative buffers” on eligible poultry farms along Lake Tenkiller and the watershed’s Scenic Rivers.

The buffers are intended to filter runoff before it enters the water.

Drummond said: “When the court asked us to strengthen the agreement, we went back to work and reached a better result. Every company has now made enforceable commitments with clear deadlines, creating a balanced solution that protects our natural resources while supporting one of Oklahoma’s most important industries.”

The case was first brought in 2005 by then-attorney general Drew Edmondson, who accused the six companies of contributing to phosphorus contamination in the river through runoff from poultry litter used as fertiliser.

In January 2023, the federal court ruled in the state’s favour.

The companies later asked the court to throw out the case, arguing that phosphorus concentrations had seen a “significant reduction” since the trial.

The federal court dismissed that claim, stating that phosphorus levels were still “alarmingly high”.

A final judgment issued in December found the companies jointly liable and mandated clean-up actions as well as limits on waste application.