How Does Chicago River Water High quality Evaluate to Lake Michigan? – Weblog

Image: Public well being researchers monitored bacterial ranges beneath seven bridges alongside the Main Stem of the Chicago River on six events main as much as the 2025 Chicago River Swim. None of the samples measured anyplace close to the 1,000-per-100 mL benchmark thought of protected for swimming proven, as proven within the evaluation. Source: University of Illinois Chicago School of Public Health

Water-quality Monitoring Reveals a Healthy River for Swimming

When almost 300 swimmers took to the Chicago River on September 21, 2025, they had been swimming in a river that a long time in the past few may have imagined would host an open-water swim. But what was the water high quality really like? It was pretty much as good as swimming in Lake Michigan.

Following the identical protocols that they use for the Chicago Park District to watch water high quality at Chicago’s Lake Michigan seashores to find out whether or not situations are acceptable for swimming, University of Illinois Chicago School of Public Health epidemiologists sampled river water beneath eight bridges alongside the Main Stem (Wabash, State, Dearborn, Clark, LaSalle, Wells, Franklin, and Wacker) on six separate days between September 2 and 17.  Every day each pattern was nicely beneath the Beach Action Value benchmark of 1,000-per-100 mL, that means the water high quality met the swimmable customary. None of the samples would have triggered a water-quality swim advisory which applies the identical customary at Chicago’s Lake Michigan seashores.

This constant discovering throughout eight places and 6 separate sampling days provides us a glimpse at simply how far the Chicago River has come. The outcomes don’t imply the Chicago River is prepared for swimming in every single place, daily. Like Lake Michigan, river water high quality modifications with situations. Heavy rainfall and mixed sewer overflows can quickly improve bacterial contamination, which is why making routine river swimming doable would require dependable monitoring and continued infrastructure enhancements corresponding to designated swimming areas, protected entry factors, ladders and different technique of coming into and exiting the water, and amenities that defend swimmers from boat site visitors.

Chicago’s Place within the Global Urban Swimming Movement

The query is now not merely whether or not folks can ever swim within the Chicago River. Swimming was authorised as a legally designated use in a lot of the river system by the Illinois Pollution Control Board and USEPA in 2011. And, we now have real-world water-quality knowledge, the Chicago River Swim, and the expertise of communities across the globe working to reclaim their city waterways for swimming to point out us what ought to occur now. The subsequent hurdle is what it should take to make a swimmable river an enduring a part of our watershed’s future. As the Chicago area faces hotter summers and more and more frequent excessive warmth, creating extra locations for folks to securely entry and funky off within the water can be a matter of local weather resilience and fairness.

This is the dialog we are going to proceed on the Chicago-Calumet River Swimming Summit: Jumping Back In on January 28 on the Peggy Notebaert Nature Museum. Join us and get extra information right here.