MADISON, Wis. -- The Sierra Club is suing the University of Wisconsin-Madison, saying it is illegally operating a power plant that is a major source of pollution in Madison.

The San Francisco-based group claimed the university violated the Clean Air Act by failing to install modern pollution controls when it performed several upgrades to the plant built in 1954.

The lawsuit alleged that the university also failed to inform the Department of Natural Resources about the work or obtain permits required for construction on power plants.

The group wants the university to replace the plant with one that uses cleaner-burning fuels or at least install technology that would drastically cut pollution there.

"As our community grows we failed to take the necessary investments in cleaning up our oldest and dirtiest sources of power plant pollution, including the Charter Street power plant," said Bruce Nilles, of the Sierra Club.

A university spokesman said the UW-Madison is reviewing the claims but he said he believes the plant complies with the law.