The Sierra Club filed a federal civil lawsuit, in Missouri, against the utility on Wednesday asking Ameren to reduce air pollution at three power plants and asks that the court issue financial penalties for past violations.
The environmental group filed a formal notice of intent to sue in December, saying Ameren's testing shows nearly 8,000 violations since March 2009 at the utility's Meramec power plant in St. Louis County; the Rush Island plant in Jefferson County; and the Labadie plant along the Missouri River in Franklin County, according to the Associated Press.
The suit comes as Ameren Missouri prepares to build a coal ash landfill next to the Labadie power plant. The utility also plans to build a coal ash landfill at Rush Island.
The Sierra Club is also involved in a separate lawsuit against Ameren in Illinois citing several federal Clean Air Act violations at the E.D. Edwards coal-fired power plant in Bartonville.