The Amazing Restoration of the Chicago River
- Apr 21
- 6 min read
How One of America’s Filthiest Waterways Became a Model of Urban Environmental Recovery
On warm spring mornings, kayakers glide past downtown Chicago’s glass towers, their paddles cutting through water that reflects the skyline in shimmering blue. Along the riverwalk, joggers and families pause to watch herons stalk fish near the shoreline. It is a scene that today feels ordinary, almost serene.
This was not the case many years ago. Instead, the Chicago River was once viewed as one of the most polluted waterways in the United States.
Now, thanks to decades of government and private efforts, this mighty river has been largely rehabilitated and now stands as an example of environmental recovery in a heavily populated and industrial urban area.
Reversing the River
For much of the 19th and early 20th centuries, the Chicago River was inundated with industrial waste from factories, runoff from slaughterhouses, and untreated sewage that flowed directly into its channels. Residents described the river as a foul, “stinking” corridor that could make a person ill simply by standing nearby. Fish populations collapsed, aquatic life struggled to survive, and by the 1920s, river swimming had all but disappeared.
The crisis forced Chicago to do something unprecedented. In 1900, engineers completed one of the most ambitious urban infrastructure projects in American history: the reversal of the Chicago River’s flow. Instead of allowing the river to dump its pollution into Lake Michigan, the city’s primary source of drinking water, engineers redirected the river inland, through the Chicago Sanitary and Ship Canal, toward the Mississippi River system.
The move helped protect public health in Chicago, but it did not solve the river’s underlying contamination problems and ended up sending its toxic waters downstream.
The river reversal was “an extraordinary engineering response to a public health emergency,” said author Richard Lanyon, former executive director of the Metropolitan Water Reclamation District of Greater Chicago.
“But reversing the river was only the beginning. It bought time. It did not clean the river,” he wrote in his 2012 book, Building the Canal to Save Chicago.
For decades after the reversal, combined sewer system overflows continued to send untreated waste during heavy rains into the river, and industrial runoff and urban development worked to destroy its water quality. By the mid-20th century, the Chicago River had become a symbol of the environmental costs of rapid industrial growth.
Policy and Infrastructure
The turning point came in the latter half of the 20th century, when environmental awareness began to reshape public policy across the United States. The Clean Water Act of 1972 marked a critical shift, establishing enforceable standards for water quality and regulating pollutant discharges.
For the Chicago River, this legislation set in motion a long-term recovery process.
“We have made a lot of progress in cleaning up historic pollution and in trying to prevent more pollution through both a system of regulation and laws and permits,” Debra Shore, a former EPA regional administrator and previously a commissioner of the Chicago area’s Metropolitan Water Reclamation District, told Goucher Magazine in 2022. “Everyone deserves safe water to drink, clean air to breathe, and to not live on contaminated soils.”
Yet policy alone was not enough. Chicago also invested in massive infrastructure projects to address one of its most persistent problems—combined sewer overflows. During storms, rainwater and sewage would overwhelm the system, sending untreated waste directly into the river. To combat this, the city undertook the Tunnel and Reservoir Plan, commonly known as the Deep Tunnel, a vast underground network designed to capture and store excess stormwater and sewage until it could be treated.
The Deep Tunnel system is one of the most significant urban water management projects ever built, according to Lanyon and many others. It dramatically reduced the frequency and volume of untreated discharges into the river.
At the same time, wastewater treatment plants were upgraded to remove more contaminants from the water. Advances in treatment technology reduced nutrient loads, improved oxygen levels, and created conditions that allowed aquatic life to return.
A River Reborn
From a scientific perspective, the river’s recovery has been striking: Improvements in water chemistry and sediment conditions have led to the gradual return of microbial communities and aquatic ecosystems.
In fact, the number of fish species inhabiting the river has risen dramatically—from 10 to 77—from 1972 to now. The fish populations “changed because the water is cleaner due to cleaner sewage management practices,” Austin Happel, research biologist at Chicago’s Shedd Aquarium, recently told Inside Climate News.
In 2025, hundreds of swimmers took part in the first organized swim in the Chicago River in nearly a century.
Today, herons, cormorants, and even bald eagles call the river home, as do beavers, otters, muskrats, and a variety of other mammals. Sections of the river that once repelled visitors now attract kayakers, anglers, and tourists. In 2025, hundreds of swimmers took part in the first organized swim in the Chicago River in nearly a century, a symbolic milestone that underscored how far the river has come.
“It’s pretty clear that the Clean Water act has played an absolutely critical role in why we’ve had decades of progress,” said Jared Policicchio, deputy chief sustainability officer for the Chicago Department of the Environment, in an interview with CBS News in 2025.
But infrastructure and regulation tell only part of the story. Civic engagement played a crucial role in transforming the river’s identity from an industrial sewer to a shared public resource.
Margaret Frisbie, executive director of Friends of the Chicago River, has spent decades advocating for the river’s restoration along with other civic groups.
“I cannot tell you what it feels like for me to stand here [amid] the magic of the river and know how many people worked together to make this happen,” she told a gathering in 2015 that opened the Chicago Riverwalk, a pedestrian promenade along the river with restaurants, bars, cafes, boat and kayak rentals, and floating wetland gardens for ecological education.
The Chicago Riverwalk [is] a pedestrian promenade along the river with restaurants, bars, cafes, boat and kayak rentals, and floating wetland gardens for ecological education.
“Friends of the Chicago River,” she continued, “was founded in 1979 to improve and protect the Chicago River. Our vision is that the Chicago River is one of the world’s greatest metropolitan rivers, and I really think that we’re on our way. We have been working for decades to improve the water and the resources for people and for wildlife, and the city’s been an extraordinary partner.”
Organizations like Friends of the Chicago River have worked to raise awareness, promote habitat restoration, and push for stronger environmental protections. Their efforts have helped reconnect Chicago residents with a waterway that had long been ignored or avoided.
Urban design has further reinforced this reconnection. Riverwalk developments, floating wetlands, and habitat restoration projects have transformed the river’s edges into accessible public spaces. These initiatives not only improve ecological conditions but also encourage people to engage with the river in everyday life.
“When people experience the river directly, whether kayaking, walking, or simply sitting by the water, it changes their perspective,” Frisbie added. “They begin to see it as something worth protecting.”
Despite its remarkable recovery, the Chicago River still faces challenges. Combined sewer overflows, though reduced, have not been entirely eliminated. Legacy pollutants remain embedded in river sediments, posing long-term risks. Urban runoff continues to carry contaminants into the waterway, particularly during heavy rainfall.
These ongoing challenges highlight an important reality. Environmental restoration is not a one-time achievement but a continuous process. Maintaining progress requires sustained investment, adaptive management, and public commitment.
Yet the Chicago River’s transformation offers a powerful example of what is possible. Once dismissed as irredeemably polluted, the river now serves as a model of urban environmental recovery, demonstrating how engineering, policy, science, and community action can work together to restore degraded ecosystems.
Its story carries lessons for cities around the world. First, large-scale environmental problems can be addressed when governments commit to long-term solutions. Second, infrastructure investments, while costly, can yield profound public health and ecological benefits. Third, public engagement is essential. When people value a natural resource, they are more likely to support its protection.
Perhaps most importantly, the Chicago River shows that even heavily damaged ecosystems can recover when given time, resources, and care.
Standing along its banks today, it is difficult to imagine that this same river was once considered beyond saving. The water may not be pristine, and the work is far from complete, but the transformation is undeniable.
Whether other cities can replicate Chicago’s success likely depends on two things: 1) their willingness to invest in infrastructure and policy and 2) embracing a vision of restoration that sees polluted waterways not as lost causes but as opportunities for renewal.
*Deborah Harvey is a writer and researcher focused on science, technology, sustainability, and global innovation. Her work explores how emerging ideas shape the future of energy, infrastructure, and the environment.
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