Dive Brief:

• The Sierra Club sued Ameren Wednesday over alleged Clean Air Act violations at three St. Louis-area coal-fired power plants.
• Sierra Club contends that the Meramec, Labadie and Rush Island plants have been emitting more soot than allowed. Ameren denies the charges.

Dive Insight:

Sierra Club has been putting pressure on coal-fired power plants around the country as part of an effort to get as many as possible to shut down. In many cases, the environmental group's suits have led to unit retirements and air emissions projects. It is no surprise that the group is targeting these older coal-fired plants.