Produced by Alma Bahman for Chicago Loopster

The plants began garnering some notice in November 2002 when the U.S. Environmental Protection Agency scaled back Clean Air Act regulations. Instead of requiring plants to upgrade to modern pollution controls when any equipment is repaired, they get a maintenance "allowance" from the governement.

This means companies have to upgrade only when they spend more than that allowance while maintaining their equipment. Companies also don't have to update pollution controls if the government reviewed them in the past decade.

Opponents to these relaxed regulations were outraged.

In August 2003, Pilsen and Little Village environmental groups - where the Fisk and Crawford plants are located - protested at hearings where the plants expected to win new air pollution permits from the Illinois EPA. In the name of health problems caused by the dirty air, the groups wanted the plants to follow stricter emissions standards and switch to cleaner burning natural gas or coal.

"They are using this permitting process to advance a different campaign of closing down coal plants," said Doug McFarlan, a spokesman for Midwest Generation, in a Chicago Tribune article. "Coal still provides half of the electricity we use in this country. We understand our plants have an impact on air quality; that's why we are trying to focus on being environmentally responsible."

In the article, McFarlan also said converting the plants to natural gas would be "economically impossible."

In August 2005, Atty. Gen. Lisa Madigan sent a letter to the Illinois EPA chronicling more than 7,600 pollution violations since 1999 between Midwest Generation's six plants, including Fisk and Crawford.

Despite the 512 violations between Fisk and Crawford, EPA official said there wasn't a problem.

Madigan’s office and the environmental groups finally sued the EPA over the plants' operation permits in September 2007. They alleged the plants have been violating air standards. Plus, Midwest Generation updated the plants’ equipment, which should have meant stricter Clean Air Act standards.

Surprisingly, around the same time, the EPA gave Midwest Generation a notice of violation, stating the same issues being brought against the EPA. Nothing really came of it.

Shortly after this first lawsuit against the EPA, more environmental groups resorted to legal action against the plants and Chicago alderman began efforts to pass the Clean Power Ordinance.

In 2011, groups like Greenpeace and supporters of shutting down the plants began to more aggressively protest the plants and Chicago's dependence on coal.

So what happened with all that legal action? Midwest Generation made a deal with the state EPA - and maybe with the city - to regulate its emissions, but it doesn't look like the battle will end any time soon.