A federal lawsuit has been filed to block a new steel mill from opening in Osceola. The Blytheville Courier News reports Nucor Steel filed a lawsuit in Jonesboro yesterday against Big River Steel. In the suit, Nucor says Big River Steel violated the federal Clean Air Act. Nucor says pollutants from Big River Steel would cause harm to the productivity of its workers. Nucor operates two steel mills outside of Blytheville. Big River Steel is planning a $1.3 billion steel mill south of Osceola. Despite objections during Big River's approval process, an air quality permit for the mill was approved by state officials in April. Big River Steel founder John Correnti tells the Associated Press that the lawsuit is frivolous.