What’s in the Chicago River and Is it Safe to Swim?

Written by Telea Dodge
Updated: September 14, 2023
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The Chicago River spans 156 miles of natural and manmade canals and riverways. The river is actually a system of rivers, and it flows through the city of Chicago in the midwestern state of Illinois. The river has an interesting history, which we will briefly touch on here while we explore what kinds of animals live in the Chicago River and answer one big question: “Is the Chicago River safe to swim in?”

The Chicago River is famous for the fact that it runs backward.

About the Chicago River

The Chicago River, as noted previously, is a river system that spans 156 total miles. It reaches a maximum depth of 21 feet and has three main branches – North, South, and Main. The river has one incredibly interesting feature – it actually flows backward! When city officials realized that raw sewage from the river was flowing into Lake Michigan – Chicago’s clean water supply – they knew they had to act. The city took measures to permanently reverse the flow of the Chicago River. Now, instead of draining into Lake Michigan, the Chicago River is fed by it.

As a result, the polluted water flows to the Mississippi River instead, by way of the Des Plaines River and the Illinois River. A man-made canal helps divert this water from the south branch of the Chicago River to the Des Plaines River called the Chicago Sanitary and Ship Canal. It’s a clever solution to a complicated problem, but it carries implications for the Mississippi River – North America’s largest watershed. Pollution is a serious problem for North America’s waterways and the wildlife that lives in and around them. The Mississippi is the most polluted river in North America, partially as a result of diversions like these.

Fortunately, there are plenty of people working on this issue. From scientists to river cleanup crews to engineers, rivers have many allies. The Chicago River has its own powerful ally – Friends of the Chicago River. This organization is the only one of its kind – an allyship that works solely to protect the Chicago River.

Dog Park Series - Chicago

A view of the Chicago River is something humans and dogs alike can appreciate.

©Page Light Studios/Shutterstock.com

The Chicago River on a Map

This interactive map shows the Chicago River where it begins as a watershed for Lake Michigan. Navy Pier features some excellent views of the river, and the riverwalk takes you along the bank of the Chicago River to a lake-front park with a view of the pier and the Franklin Delano Roosevelt Bridge.

Pollution in the Chicago River

Unfortunately, pollution threatens the Chicago River. Heavy industry plays a huge role in this pollution. Runoff from streets is also a risk for the river – the oils and trash from cars and human use make their way to the river. Additionally, the storm-sewer system that Chicago utilizes has a heavy impact on the river. Engineers built the system in the 1850s as a response to the need for a better sewage system than open gutters. At the time, a combined storm and sewage system seemed like a great idea. However, as the population of the city grew and the need for freshwater increased, the system became outdated.

Let’s explain that. First, population growth directly impacts sewage systems. Any sewage system has a maximum number of people it can accommodate. You have to expand your sewage processing capabilities as you expand your population. Next, climate change is responsible for an increased number of heavy rainfalls in the area. This poses a risk to a combined storm and sewage system. The city works very hard to address these issues, including adding additional sewage piping to divert wastewater to treatment facilities. Unfortunately, heavy rainfall will still cause the system to back up and flood. Runoff, untreated sewage, and any trash and noxious liquids dumped into regional drains all make their way to the river when the system floods. These events are called ‘combined sewer flows’, and they are catastrophic to the water habitats that so many creatures rely on for life.

Even without this factor, the river still takes on too much. Pollution from agriculture and industry, along with runoff from trash and oil-covered streets, puts this hybrid ecosystem at risk. The canals made to widen the river are helpful and hurtful to its course.

River Cleanup Efforts

All Chicago River Drawbridges raised elevated at the same time under a clear blue sky in summer

Thanks to cleanup efforts, the waters that run through Chicago are far less polluted than they were only a few decades ago.


You might think that the Chicago River faces a dismal fate, but think again. With the help of various organizations and environmental agencies, the river has actually gotten a lot cleaner! The Clean Water Act of 1972 did a lot to help turn the tables for this river and canal system. This act changed the course of the river’s history by rewriting laws across the United States to prevent pollution build-up in rivers. The act includes new guidelines for the treatment of wastewater and updates on the legality of dumping chemicals and other pollutants into the nation’s waterways.

Residents are also doing their part. Several different groups work diligently to keep trash and other contaminants out of the river. Now, the waters that run through Chicago are far less polluted than they were only a few decades ago.

Only 10 species of fish remained in the Chicago River during the 70s. Now, over 70 species of fish populate its waters. A fish hotel – an underwater manmade habitat – helps fish thrive in the artificial canals in the river. Because of the better water quality and the other work put in to create a healthier habitat, fishing is once again a part of recreation on the Chicago River.

Is the Chicago River Safe to Swim in?

Unfortunately, despite all of these efforts, we still do not recommend taking a dip in the Chicago River. The water quality has improved drastically since the 1970s, but the waterways still face challenges. Much less litter pollutes the banks, but unseen dangers still lie below.

City officials do not recommend swimming in the water – yet. They are very proud of the cleanup efforts so far, but it is bacteria and other less visible risk factors that stop them from clearing swimming in the area. The water still has high levels of fecal coliforms such as E. coli. Since raw sewage still does make its way into the river, anyone swimming in its waters is risking exposure and illness. The local government recommends visiting a physician if you end up taking a dip. Other dangers may include sharp trash or glass that still rests at the bottom of the river. Despite this, the city has made incredible progress toward clean water. City officials even drew attention to this fact by risking a dip of their own. Still, they do not think it’s safe for residents to be going for a swim – yet.

Wildlife in the Chicago River

river otters

The pollution of the Chicago River deeply impacted many animal species that depend on it.


Humans aren’t the only creatures facing challenges with their water supply. The pollution of the Chicago River deeply impacted many animal species. Luckily, the water cleanup efforts have proven helpful in restoring habitats for many animals. We mentioned before that the fish population in the Chicago River is growing again. This population includes species such as American eels, black bullheads, green sunfish, largemouth bass, and northern pike.

Aside from fish, many mammals depend on the river for life, especially bats. There are 12 species of bat native to the state of Illinois. Most of these species live along the Chicago Riverway. Friends of the Chicago River is helping preserve bat habitats along the river, recognizing that bats are incredibly water-dependent as a species and rely on the Chicago River for food, water, and shelter.

You may see other common animals while walking along the river. Muskrats, river otters, raccoons, and striped skunks all stop along the banks. You may even see some white-tail deer, especially in less populated neighborhoods. Squirrels bounce around everywhere – by the river and around the city. Several bird species also depend on the water that runs through the channels. Bank swallows, double-crested cormorants, osprey, and mallard ducks enjoy the cool waters. This knowledge instills how pressing it is that efforts are continued to clean up, protect, and preserve the waters of the Chicago River. Many are depending on it.

The photo featured at the top of this post is © vichie81/Shutterstock.com

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About the Author

Telea Dodge is an animal enthusiast and nature fiend with a particular interest in teaching a sense of community and compassion through interactions with the world at large. Carrying a passion for wild foraging, animal behaviorism, traveling, and music, Telea spends their free time practicing their hobbies while exploring with their companion dog, Spectre.

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