From a plane, it would be easy to think one of the nation's dirtiest power plants is within the Chicago city limits.
But the aging State Line Power Station, a major contributor to the city's chronically dirty air, sits just a few hundred feet over the state border in Indiana, leaving it largely unnoticed and untouched during a decades-long effort to transform the Chicago area's smog-choked history.
Protesters regularly march in front of two other coal-fired power plants in Pilsen and Little Village, demanding an end to noxious pollution that wafts into the Chicago neighborhoods. Federal and state prosecutors are suing the owner of the plants to force significant cuts in smog- and soot-forming emissions.
Yet a Tribune analysis reveals that the State Line plant, built along Lake Michigan by ComEd in 1929 and bought by Virginia-based Dominion Resources in 2002, is far dirtier than either of the Chicago plants. It emits more lung-damaging nitrogen oxide than the Pilsen and Little Village plants combined, and churns more sulfur dioxide and toxic mercury into the air than either plant.
Only a dozen other coal plants nationwide emit more nitrogen oxide in relation to the amount of electricity generated — a sign of how much less efficient State Line is than bigger, cleaner power plants.
State Line also is a fish killer, one of several old plants around the Great Lakes allowed to suck up millions of gallons of water to cool equipment, then pump it back out steaming hot. Illinois and Indiana banned the technology at newer plants decades ago because it is so destructive to aquatic life.
"It's a highly polluting plant that has existed for years in a sort of never-never land," said Howard Learner, president of the Environmental Law and Policy Center.
That may be changing. Last year, officials in the U.S. Environmental Protection Agency's Chicago office quietly accused ComEd and Dominion of repeatedly violating federal soot limits and upgrading State Line without installing required pollution controls.
Although President Barack Obama's administration is targeting dirty old coal plants around the nation for aggressive enforcement, it so far has held off filing a lawsuit against State Line, prompting environmental groups recently to nudge the EPA by threatening their own legal action.
Responding to questions, Dominion said it decided earlier this year that it isn't worth cleaning up the company's sooty relic. It plans to keep selling State Line's electricity on the open market until a federal lawsuit or tougher pollution rules make it too costly to keep operating the plant.
"We aren't going to make significant capital expenditures in the future at State Line," said Jim Norvelle, a Dominion spokesman.
Sandwiched between Lake Michigan and the Chicago Skyway, the power plant is the first of several big industrial polluters encountered on a drive along the lake's southwestern shore from Illinois to Indiana. The only road into the plant's arched brick entrance begins in Chicago's East Side neighborhood near Calumet Park.
State Line once was the nation's largest power plant. Its latest pair of coal-fired steam turbines, installed in the late 1950s and early 1960s, generate enough electricity for about 100,000 homes.
As environmental laws forced dozens of other coal plants to clean up or shut down, State Line's owners largely avoided the toughest provisions of the federal Clean Air Act and other regulations. Regulators during the 1970s exempted dozens of old plants like State Line after utilities said they wouldn't be running much longer.
Four decades later, complaints about State Line are motivated in part by new research showing that people living in the Chicago area face some of the nation's worst health risks from coal plant pollution, which has been linked to cancer, lung disease and heart problems.
In the metropolitan region that stretches around Lake Michigan from Kenosha to Naperville to Gary, 347 people die, 584 suffer heart attacks and 264 are admitted to emergency rooms each year as a result of exposure to coal plant pollution, according to an analysis commissioned by the Clean Air Task Force, a Boston-based environmental group.
Only New York and Philadelphia record more deaths and illnesses from coal plant pollution, the group concluded after relying on peer-reviewed methods endorsed by the EPA and National Academy of Sciences.
Illinois officials have documented that pollution drifting from northwest Indiana is a big contributor to the Chicago area's dirty air problems. While air pollution locally and nationwide is declining, State Line's emissions have remained relatively constant for years.