The Chicago River, a defining feature of the city’s urban landscape, often prompts questions about its environmental health. Its iconic status, from its role in the city’s history to its vibrant present-day Riverwalk, sparks curiosity regarding its ecological condition. This article examines the river’s cleanliness, its past, current challenges, and ongoing efforts to foster a healthier waterway for Chicago.
Current State of the River
Assessing the Chicago River’s water quality involves examining various indicators of its overall health. Key metrics include dissolved oxygen levels, vital for aquatic life, and bacteria counts such as E. coli, indicating fecal contamination. Chemical pollutants from various sources are also regularly monitored. Significant improvements have been made over time, allowing for a more diverse ecosystem.
The Metropolitan Water Reclamation District of Greater Chicago (MWRD) and Friends of the Chicago River actively monitor the river’s conditions. H2NOW Chicago, a pilot project by Current, utilizes sensors to provide real-time data on microbial pollution, including E. coli levels, offering immediate insights into water quality. These efforts support a growing number of fish species, increasing from 10 types in 1974 to over 80 species today.
A River Transformed: Historical Perspective
Historically, the Chicago River existed in a natural state before extensive human intervention. As Chicago rapidly industrialized in the late 1800s, the river became heavily polluted with sewage and industrial waste. This waste flowed directly into Lake Michigan, the city’s primary source of drinking water. The threat of disease outbreaks like cholera and typhoid prompted a radical engineering solution.
In response to public health concerns, the Sanitary District of Chicago (now MWRD) undertook the ambitious project of reversing the river’s flow. The Chicago Sanitary and Ship Canal, a 28-mile waterway, was completed on January 2, 1900. This redirected the river’s discharge away from Lake Michigan towards the Des Plaines River, eventually reaching the Mississippi River system. This monumental feat transformed the river into what author Upton Sinclair described as an “open sewer,” highlighting the severe environmental degradation of the era.
Addressing Water Quality Challenges
Despite the historic reversal, the Chicago River continues to face water quality challenges primarily from combined sewer overflows (CSOs) and stormwater runoff. Chicago’s combined sewer system carries both sewage and stormwater in the same pipes. During heavy rains, as little as 0.3 inches of precipitation can overwhelm this system, leading to untreated wastewater and stormwater discharge directly into the river. Stormwater runoff also carries pollutants such as oil, litter, sediment, heavy metals, and nutrients from urban surfaces into the waterways.
To mitigate these issues, the MWRD implemented the Tunnel and Reservoir Plan (TARP), often called the “Deep Tunnel” project, in the mid-1970s. This large-scale engineering initiative involves 110 miles of deep tunnels and vast reservoirs designed to capture and store combined sewage and stormwater until it can be treated at reclamation plants. Since its initial tunnels became operational in 1981, TARP has significantly reduced CSOs, bringing the average number of overflow days per year down from over 100 to approximately 50. Green infrastructure initiatives, such as permeable pavement, green roofs, and rain gardens, are also being implemented to manage stormwater closer to its source. Community-led efforts, like the annual Chicago River Day, further contribute to cleanup by removing trash and invasive plants.
Recreation and Public Access
Improvements in the Chicago River’s water quality have expanded opportunities for recreation and public access. Activities such as kayaking, boating, and fishing are now common along various stretches of the river. The Chicago Riverwalk, a pedestrian path, has also enhanced public enjoyment and connection to the waterway.
While recreational activities are encouraged, safety precautions remain important. Individuals engaging in water contact activities like kayaking are advised to avoid ingesting river water and to wash thoroughly with soap and water after contact, due to the potential presence of bacteria like E. coli. Wearing a personal flotation device is mandatory for kayakers, and awareness of commercial boat traffic and currents is important for safety. An open-water swim in the Chicago River is planned for September 2025, marking the first such event in nearly a century and signaling increasing confidence in the river’s improving conditions.