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

CHICAGO — When organizers announced their plans for an open swim in the Chicago River in September, residents across the city raised their eyebrows.

The days when the river was a dumping ground for the largest slaughterhouse in the world are long past. And, sewage that once flowed directly into the river is now funneled through wastewater treatment plants first. But when powerful storms hit the city, sewage and stormwater runoff spill into local waterways raising bacteria levels.

Caitlin Jonassen, a lifelong Chicagoan, said she would not even consider swimming in the river. Last year, she said she was getting in a kayak near the end of the swim’s planned course when she fell in.

“Not only was it freezing, and I was extremely grossed out by the masses of who knows what floating close by, but I actually broke out in a horrible rash all over that took a couple of days to clear,” Jonassen said. “It was a pretty horrific experience. As a Chicago native, I wish the river could be cleaned up enough where I would trust swimming in it, but for now it’s extremely far away from that for me.”

Still, swimming in the river, which has improved dramatically over the past few decades, can be done safely, according to many experts.

“A lot of people think about the Chicago River as being super gross, super polluted,” Elsa Anderson, an assistant professor of environmental science at Northwestern University, said. “And at one point in time, that was true. But with the Clean Water Act in the early 1970s, it’s not.”

Anderson said scientists have been able to measure the river’s improvement by looking at the vast increase in fish and plant species. The river has become a thriving wetland, according to Anderson.

Since the announcement of the race three weeks ago, more than 1,100 swimmers have applied to compete, said organizer Doug McConnell, who emphasized that safety is a priority. McConnell is still working on getting approval from the city.

McConnell, who has swum the English Channel, Manhattan Island and Tampa Bay, said participants will be heavily screened and carefully selected.

“We are going to make sure the people that actually go into the water are really qualified,” McConnell said. “These are people who have swum the English Channel, swum Amsterdam, or done other urban swims and know what they’re getting themselves into.”

How long ago it rained

Though the river may be improving, organized swimming hasn’t been authorized in more than a century.

Timothy Hoellein, an aquatic ecologist at Loyola University Chicago who studies urban ecosystems, said that’s because heavy rains and a large urban population can contribute to dangerous conditions.

Chicago has a combined sewer system, which means stormwater runoff and sewage flow through the same pipes. That waste is decontaminated at a wastewater treatment plant, which removes disease-causing organisms before they enter the river.

But, intense downpours can overwhelm the system and cause overflows that send untreated runoff and human waste directly into the river.

According to the Metropolitan Water Reclamation District, sewage was discharged into the Chicago River because of heavy rains a handful of times last summer.

So much rain fell over the July 1 weekend that waste and runoff poured out of nearly a dozen overflow pipes across Cook County, from Evanston to Westchester, many for hours at a time. MWRD had to open the locks near Navy Pier to relieve pressure on the system, allowing more than 1.1 billion gallons of waste to flow into Lake Michigan.

“There’s been really, really major changes in how we manage our drinking water, and our wastewater and our environmental footprint as it relates to the river,” Hoellein said. “But when there’s been one of these combined sewer overflows, there’s more potential for disease-causing organisms and microbes in the water.”

As long as everything in the river has gone through a wastewater treatment plant, Hoellein added, it’s safe to swim.

“Whether I’d get in depends on how long ago it rained very hard,” Hollein said. “A couple of days or a week or so after, I think it would probably would be OK. But if you’re talking like right after a big rainfall or right after a plant overflow, I would not (get in).”

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.”

A final step

A Long Swim is inviting 500 participants to swim 2.4 miles from the Clark Street Bridge through a loop course between State Street and Wolf Point. The event will support ALS research at Northwestern University and has long been a dream for McConnell, a Chicago-area native who lost his dad to ALS.

“We wanted it to be in Chicago, because we’re from here, Northwestern is here, and we’ve got this fabulous resource in the form of the Chicago River,” McConnell said. “It’s really the whole reason Chicago is here in the first place.”

While McConnell said he has been in touch with the U.S. Coast Guard, he hasn’t received approval or the appropriate permits from the city –– despite opening applications for the race.

Ald. Bill Conway, 34th, whose ward is where the swim would take place, said he was surprised to learn the event had been planned without collaboration with his office or the Chicago Department of Cultural Affairs and Special Events.

At a Cultural Affairs meeting earlier this month, Conway asked city officials about the event and was told it had not yet been permitted.

“Moving forward, it’s important that they coordinate closely with DCASE and area alders to obtain the appropriate permits and ensure this event can be done safely for both participants and residents in our community,” Conway said.

McConnell said A Long Swim is working toward getting city approval and is hopeful the event will proceed as planned.

“We’re working with the Coast Guard, who is coordinating with the city,” he said. “We want to make sure we have the most successful and safe event possible.”