Water quality has improved dramatically in the Chicago River. But how safe is swimming?

Monitoring bacteria levels

MWRD records and regularly publishes the amount of fecal coliform in the river.

Drinking or coming into contact with elevated levels of this type of bacteria may cause an upset stomach, vomiting, fever or diarrhea. It can also cause serious conditions or death in vulnerable populations such as children, older people and those with weak immune systems.

According to the Illinois Department of Public Health, the maximum safe level of fecal coliform in freshwater is 500 colony-forming units per 100 milliliters of water. In 2023, MWRD reported an average of 1,536 cfu per 100 ml at Wells Street –– where swimmers will be –– down from a 2022 average of 5,290 cfu per 100 ml.

McConnell said the threat of a combined sewer overflow was front of mind in planning the event. The group picked September, Chicago’s driest month, and chose the downtown section of the river purposely to avoid contaminants.

Hoellein said water in the downtown strip of the Chicago River water primarily flows from the lake. Somewhere like the North Shore Channel is far more likely to see raw sewage, he said.

Still, McConnell said his nonprofit A Long Swim, which is putting on the event, will monitor water safety up until the day of the swim using data from MWRD and H2NOW Chicago, a water quality monitoring system in the Chicago River that updates every 15 minutes. In the event of a combined sewage overflow, he said, the event will be canceled.

“We will monitor bacteria levels in the water, just like they do bacteria levels at Oak Street Beach, or, you know, at the indoor pools of health clubs,” McConnell said.

Laura Kochevar, who is from the Chicago area, said she kayaks in the river every couple of weeks. She said she’s increasingly seen birds, fish and turtles on her trips, and she applied to swim in September’s event.

“They have a lot of safety measures in place, and I’m very comfortable,” she said. “People just have ‘The Jungle’ by Upton Sinclair in mind, but that’s from 1905. That image of a meatpacking plant is just cemented in their mind, and that’s not the case any longer.”

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