MADISON, Wis. -- A federal judge said a 53-year-old power plant operated by the state and the University of Wisconsin-Madison has been in violation of the federal Clean Air Act for five years.

U.S. District Judge John Shabaz issued the ruling in response to a lawsuit filed by the Sierra Club.

The lawsuit claimed the university violated the Clean Air Act by failing to install modern pollution controls when it performed several upgrades to keep the power plant operating.

A spokesman for the university did not immediately respond to a message. A spokeswoman for the state Department of Administration also did not immediately respond to a message.