The world's largest poultry producer, Tyson Foods, is among nearly a dozen poultry companies that have less than two months to reach agreement with the state of Oklahoma on how to clean a watershed polluted by chicken litter. U.S. District Judge Gregory Frizzell in Tulsa ruled Wednesday that Arkansas-based Tyson Foods, Minnesota-based Cargill Inc. and other companies polluted the Illinois River, caused a public nuisance and trespassed by spreading the litter, or manure, on land in eastern Oklahoma, and that it then leached into the river's watershed. The companies and the state have until March 17 to present an agreement on how to remedy the pollution's effects, which includes low oxygen levels in the river, algae growth and damage to the fish population.