For more than a century, the river has served a serious purpose -- keeping sewage out of Lake Michigan, which is the source of the city's drinking water. But in recent years, a growing number of people have also been using the river for boating, kayaking, and other activities. Now the federal government and others say it's time to clean it up.
"The fact is we can't have a world class city like Chicago with a third world river running through the heart of it," Ann Alexander, Natural Resources Defense Council, said.
"This is one of the most pressing water pollution issues facing rivers in America, affecting the lives of millions of people. And it's something we know how to fix," Jessica Dexter, Environmental Law and Policy Center, said.
The Chicago River has long been regarded as an open sewer with billions of gallons of partially-treated waste being dumped into the waterway every year. But in the past decade, the city has spent tens of millions to improve public access with river walks, restaurants, parks and playgrounds nearby. Riverfront condos and apartments have also sprouted up.
"The river flows through neighborhoods. It goes through people's backyards. It goes by parks," Margaret Frisbie, Friends of the Chicago River, said. "If the water's splashing, this is getting aerated. I can breathe it in, and I can get sick even if I'm on a motor boat, and I don't think I got wet."
Cleaning the river would require tens of millions of dollars worth of disinfecting chemicals. The independent agency that oversees the river, The Metropolitan Water Reclamation District, questions the cost and effectiveness. Some residents also wonder if it's worth it.
"It's a matter of priorities, yeah. I mean the city has bigger priorities than the river right now," Alex Mahlis, resident, said.
Last week, the U.S. EPA ordered Illinois officials to impose stricter water quality standards for the river. The plan is backed by the new mayor.
"We have a front yard to take care of, which is our lakefront, and we have a backyard to take care of, which is our riverfront," Mayor Rahm Emanuel said.
"What the EPA is asking is very reasonable. It's something that's being done in just about every other city in the United States and every major city in the United States," Gary Belan, American Rivers, said.
The Metropolitan Water Reclamation District, which is independent from the city and state, has not responded to ABC7's request for a statement. The Illinois EPA says it's been trying to clean up the river, but the regulatory process has been dragging on for three years.