The State Line Power Plant's age meant that it was not fitted with many of the pollution control equipment that is mandated on more modern generating plants. Instead, State Line's operations were grandfathered, giving the plant the right to vent nitrogen oxides, airborne mercury, and sulphur dioxide into the air. According to a September 2010 article in the Chicago Tribune, the State Line Power Plant was described as one of the greatest single point-source contributors to the Chicago area's ongoing noncompliant status under the Clean Air Act.
