CHICAGO -- To the casual driver, the shuttered steel mills and landfills rising around the "Skyway" connecting Chicago and northwest Indiana are the remnants of a long-past industrial age. To people living in the shadows of the elevated highway, they are visible signs of a continuing environmental nightmare.

"We feel like we're living in an island of garbage," said Virginia Cap, 70, a 35-year resident of Hegewisch, a tightly knit, working-class neighborhood on the far southeast side of Chicago.

Cap exaggerates only a little. Hegewisch borders what is arguably one of the nation's most polluted areas, a six-square-mile region known as Lake Calumet, named for the shallow lake and marshes that have been Chicago's official dumping ground since the mid-19th century.

By the city's count, the Lake Calumet area has 51 landfills and dump sites, more per square mile than any other region of the country, according to environmentalists. In addition, thousands of tons of chemicals, sludge and other pollutants have been dumped illegally, creating what Mayor Richard M. Daley has termed a "toxic wasteland."

Such contamination has helped to create a thriving grass-roots environmental movement amid what seems an unlikely, blue-collar setting. Far from the stereotype of environmentalists as yuppies in Birkenstock sandals and L.L. Bean shirts, this assortment of schoolteachers, factory workers, public-housing residents and young activists has struggled for more than a decade to fight polluters and the waste industry.

Their rallying cry is simple and pointed: "No Dumps, No Deals."

In recent years, the activists have enjoyed notable successes. They persuaded the late mayor Harold Washington to ban new dumps and incinerators on the southeast side, and they focused attention on environmental problems at a Chemical Waste Management Inc. incinerator, shut down since an explosion damaged its furnace last year.

This summer, residents won what they considered their greatest victory when Daley declined to build the region's proposed third airport near Lake Calumet. His airport plan ignited anger on the southeast side largely because thousands of residences would have been demolished. Environmental activists said it would have destroyed valuable wetlands.

The Lake Calumet area was almost entirely marsh or swamp until the late 19th and early 20th centuries, when industrialists began filling in the area to build factories while discharging untreated liquid and garbage into its rivers and lakes.

The area became one of the country's most vibrant manufacturing centers, with giant steel and chemical plants taking root near easy access to Lake Michigan and a national railroad network junction in southeast Chicago. The region's fortune soured in the early 1980s with the decline of the steel industry and the loss of thousands of manufacturing jobs, which left behind empty plants and many environmental problems.

Today, one of the most curious aspects of Lake Calumet is that alongside heaping mounds of trash and abandoned buildings are stretches of prairies, marshes and open space that constitute the last place one can legally hunt in the city of Chicago.

On the banks of Indian Ridge Marsh, a visitor can watch the flight of the great egret, a giant white bird with a nearly four-foot wingspan. Seven endangered birds, including the egret and the black crown night heron, live in the vicinity of Lake Calumet.

Bud Polk, an amateur birder and a civic activist, said many workers grew up in this "urban wilderness" and are instinctively receptive to environmental concerns. "People may not be able to name a bird or a plant," he said, "but there is a deep appreciation."

Many residents have more basic concerns. Cap, a homemaker, said she began organizing after becoming fed up with the smell of steadily advancing incinerators near Hegewisch. "We couldn't open our windows," she said. "It stunk. Seven days a week, we were like prisoners in our own home."

Marian Byrnes, a retired public schoolteacher, tells of finding in her mailbox one day in 1979 a notice that the Chicago Transit Authority was planning a bus garage on 150 acres of beautiful open space in the back of her house. She helped to organize protests that blocked the garage and has been among principal organizers of protests against toxic-waste dumps, to the point of getting arrested during a rally blocking entrance to Chemical Waste Management's incinerator in 1990.

"We've been receiving the city's garbage for the last 100 years," said Byrnes, 66. "It's enough already, and it's definitely unfair for any more of it to come to the southeast side."

For state Rep. Clem Balanoff (D), who represents the region in the Illinois House, the issue struck home when he met several children with cancer during his first campaign for public office a few years ago. No one has documented a link between Lake Calumet's toxic waste and elevated cancer rates, but Balanoff and others have expressed strong suspicions.

They point, for instance, to state Department of Public Health studies that found higher-than-expected rates of lung and bladder cancer among area residents. "Cancer is something that touches the lives of just about everyone on the southeast side, whether it's your family, neighbor or child," Balanoff said.

Citizens in similar working-class areas nationwide have become increasingly vocal about environmental issues. Not only have such neighborhoods frequently been the target of industries that treat and dispose of waste, but national environmental groups also have often ignored local concerns while focusing on such national legislation as the clean air and water acts, according to Kevin Greene, research director for the Chicago office of Citizens for a Better Environment.

"You have a number of grass-roots groups emerging to deal with local problems in the absence of the {national} groups," he said. "The people were very frustrated. They decided to take matters into their own hands."

Not everyone is happy with the results. Mary T. Ryan, a vice president of Waste Management of North America Inc., which operates a landfill in the area, said activists focus considerable ire on the waste-disposal industry, which cleans up after the fact, rather than on large manufacturers that initially caused the pollution.

"I find that kind of amusing," she said. "Is it because these industries provide more jobs and are viewed more differently than we are?"

For all of their success in halting new landfills, activists have little to show in actual cleanup of spilled waste. Some experts said the price of a cleanup could reach $2 billion.

City officials said neighbors squandered a major opportunity to obtain a large portion of that money by opposing the new airport, because Daley had promised to set aside hundreds of millions of dollars for environmental cleanup. Now activists are promoting a longstanding idea to turn the area into a 2,400-acre ecological park.

Another obvious source of money, the federal Superfund program, has been unavailable to southeast Chicago because of a Catch 22: Superfund dollars are rare, so priority is given to cleanup sites where toxic contamination directly threatens drinking water.

No such link has been established here, although there are indications that groundwater beneath Lake Calumet, contaminated from years of environmental degradation, has been leaking into Lake Michigan, the source of drinking water for 5 million Chicago-area residents.

Rep. George E. Sangmeister (D-Ill.) recently obtained federal funds to study the possible link.

While an industrial revival occasionally appears to be underway around Lake Calumet, activists said business will never embrace the region until its environmental problems are solved.

"Businesses are reluctant to relocate here because of the potential liability," Balanoff said. "People understand that if we take care of the environmental problems, this is one of the only ways we're going to attract development."