Flooding in Chicago is a getting worse. Here's why.

In a little-noticed memo early last year, Illinois scientists made a dire prediction.

“Bulletin 76,” a communication from University of Illinois researchers, warned that intense rain made worse by climate change was going to get a lot more severe in the next 25 years.

“What is considered safe and adequate today may not hold true in the future,” they wrote of the threat to homes, buildings and people.

The threat has been building for years. Over the past century in Chicago, the likelihood of heavy rainstorms has increased sevenfold. These storms can drop more than 8.5 inches of rain in 24 hours.

Designed decades ago, Chicago’s sewers can handle just 2 inches in that short period of time before flooding becomes likely.

That means every neighborhood in Chicago is at risk of flooding, and that threat rises with every big storm.

A half-century ago, construction on the so-called Deep Tunnel began to improve the old method of flood control in the city: dumping sewer water directly into the Chicago River, a practice that continues today, though less frequently.

The multibillion-dollar system of underground tunnels and massive reservoirs designed to capture floodwater has worked to help protect the river, as well as Lake Michigan. But it hasn’t stopped neighborhood sewer systems, which carry both stormwater and everything flushed down toilets, from backing up into home basements through drains, destroying property and creating unhealthy conditions.

Chicago was built on a swamp and has always had flooding problems. Stronger thunderstorms, fueled in part by climate change, are overwhelming the city’s sewers. The rain is falling so hard and so fast that the water doesn’t have a chance of flowing to those massive pipes built under the Deep Tunnel project.

Damage estimates to Chicago homes and other property have skyrocketed to billions of dollars in the past 20 years, government records show.

But the bulletin from climate scientists last year wasn’t just a warning. It was a call to action, one that politicians, planners and engineers can heed or face catastrophic consequences.

To get a sense of how bad it can be, consider what happened in 2023, when storms drenched the West Side, South Side and nearby suburbs with 8 to 9 inches over a short period.

Sewers were overwhelmed, flooding tens of thousands of homes and driving hundreds of people to find shelter elsewhere from the rain. Many hundreds, if not thousands, are believed to still be living with mold as a result of the water that surged inside, pouring in through drains and even basement walls.

“This is a serious public health issue,” says Clabe Johnson, whose apartment in Austin was inundated with 4 feet of water in July 2023.

He says his brother Gene, who was staying with him, suffered respiratory problems from lingering mold and was hospitalized.

“We felt powerless and helpless,” he says.

More rain, more problems

Across the West Side, community advocates say residents are still plagued with mold from that storm.

Even more flood survivors across Chicago and Cook County are still waiting for government help after the deluge of 2023.

“Without changes, we’re going to see an increase in [disaster] impacts,” says Illinois state climatologist Trent Ford, who consulted on the 2025 memo, which warned that the amount of rain falling in 24 hours during these storms could grow by another inch by 2050.

Even an increase of a quarter-inch of rain can affect hundreds of people and cause millions of dollars in additional damage from flooding, Ford says.

The key to prevent flooding, many experts agree, involves creating more green spaces to help soak up the excess water before it reaches the sewers — and building more underground infrastructure to capture or divert the water somewhere else.

The challenge is these solutions can take many years and cost millions if not billions of dollars.

Cities in Illinois and across the United States already are far behind in the race to counter nature’s destructive forces, experts say.

Outdated infrastructure, such as sewers and streets, and overbuilt, dense urban areas planned decades ago with far too much concrete and too few greenways turn major storms into severe flooding events. With fewer permeable surfaces, the water has nowhere to go. The built environment is as much a culprit as the intensifying weather.

The overwhelming majority of people experiencing the greatest impact are in Black and Latino communities where buildings, streets and other infrastructure have seen fewer improvements.

These areas often feature large stretches of pavement and other hard surfaces built over low-lying areas or other places with poor drainage and a lack of green space.

‘People are traumatized every time it rains’

In July 2023, Austin, the West Side neighborhood where Mayor Brandon Johnson lives, was hit with a historic flood that overwhelmed the sewer following more than 8 inches of rain, forcing hundreds from their basement apartments and creating geysers that even blew the lid off of a manhole cover, according to one witness.

That was just one neighborhood. That storm flooded at least 70,000 West Side and suburban basements in summer 2023.

And many people faced cleaning up the mess on their own. Private insurance generally doesn't cover flood damage and federal aid can be hard to come by and often is delayed, which is what has happened in Chicago.

The city was awarded $426 million last year by the federal government for “disaster recovery purposes” after the 2023 flooding. But nearly three years later, none of that money has been spent.

That’s terrible news, according to Princess Shaw of North Lawndale, who has been advocating for speedy help to West Side flood survivors who have been waiting for assistance with construction and mold removal for the past three years.

“People are traumatized every time it rains,” she says.

She sees a lack of accountability among city and state politicians and bureaucrats and calls government efforts to address the problem disjointed: “There is a lot of finger-pointing.”

In a statement, Mayor Johnson blamed the procedures for securing federal money. He also noted the need for improvements to reduce flooding.

“These are my neighbors, and as a fellow West Sider, I share their frustration with this process,” Johnson said. “The infrastructure deficiencies which exacerbated the effects of this storm reflect decades of systemic underinvestment in West Side communities.”

For that same 2023 storm, Cook County was awarded $244 million from the federal housing department.

None of the Chicago or Cook County grant money has been spent.

Is Chicago taking this problem seriously? Clabe Johnson doesn’t think so. “They turn a deaf ear.”

“I almost lost my brother. Nobody explained the severity,” he says. “What about our seniors? What about our disabled people in this community who have no voice?”

Outside of Chicago, Cicero was hit just as hard by the 2023 storm and continues to seek government assistance. The same year, Calumet City experienced a 500-year flood that paralyzed the community.

Chatham has been flooding for decades

While these communities have been hit more recently, Chatham has long been harmed by extreme flooding. A low-lying area, Chatham was built on former marshland. In the mid- to late 1800s, the area was so swampy it was known as Mud Lake.

Once entirely white, Chatham’s population became predominantly Black by 1960.

Cheryl Watson’s family was one of the first Black homeowners on her block, she says. Despite decades of flooding in her neighborhood, solutions never followed.

“It’s always the Black communities, because we have the least representation,” says Watson, who works on flooding mitigation. “Everybody leaves us hanging.”

Watson remembers her father would head down to the basement of her family home in the 1970s. Along with other men from the neighborhood, her dad would routinely remove damaged items and clean up the muck after hard rains.

Now 70, Watson returned to her childhood home after her parents died. She has a sump pump in her basement that helps with the stormwater, but that hasn’t completely solved the problem.

Chatham has a number of strikes against it. Besides once being a marsh, what’s now the Dan Ryan Expressway, built in the 1960s, divides the community. Watson says it’s long been known that Chatham is in a flood-prone area of the city. But little has been done to improve the situation, she says.

“I’ve seen all these starts and stops,” she says.

Some communities hit harder than others

While Chatham faces some particular challenges, it fits a model for flood vulnerability.

An analysis by the not-for-profit Center for Neighborhood Technology found that Chicago communities with the most federal flood-disaster claims between 2007 and 2016 were almost all — 96% — from communities of color. They include West Side communities of Belmont Cragin, Austin and Humboldt Park and areas south to Ashburn, then east to Auburn Gresham and Chatham and south to Roseland and South Deering.

“The most vulnerable communities are being hit now repetitively,” says Cyatharine Alias, who is the group’s urban resilience director. “The history of our region, the lack of investment in so many communities and the lack of maintenance on the infrastructure is what is leading to a lot of the flooding.”

‘These people didn’t have a place to sleep’

Jacqueline Reed knows a lot about that. Once a week, Reed holds a community meeting at Every Block a Village church at which people share experiences, work to solve problems and pray.

Flooding has been a pressing topic there for the past three years.

Reed, who heads the Westside Long Term Recovery Group, which advocates for aid to flooding survivors, describes the soaked mattresses and valuables pulled from many dozens of basement apartments across Austin, many of them occupied by seniors.

Volunteers waded through waist-high water after the 2023 floods to help people whose homes were affected. Mattresses and valuables floated in the dirty water that came up through the sewer drains. Crews of volunteers helped clean out “the muck.”

“These people didn’t have a place to sleep,” says Reed, who spent years pleading with the city to provide money to people who were hit by the flooding.

She and others helped pull together private money and some small amounts of city dollars. But they say it’s a slow process.

How to flood-proof Chicago

Potential ways to help prevent flooding are expensive. They include fixes that would contain flood water through traditional pipes and structures as well as natural sources, like green spaces with plants and trees that can help absorb the overflow when sewers are full.

“One of the problems with flood management in the U.S. today is: A flood happens. It’s an emergency. The government drops a whole lot of money. They build the exact same thing that they had before,” says Howard Neukrug, a University of Pennsylvania professor and former city of Philadelphia official who led stormwater management strategy.

Chicago and other cities can include green solutions, but those will only go so far, he says. More tunnels and water storage are needed. And one of the hardest choices of all will be determining that some areas essentially aren’t livable and ultimately will need to be abandoned.

Still, small fixes can also make a difference. For instance, there are more than 40 playgrounds around Chicago that are built to capture stormwater underneath in a containment space. These playgrounds include South Side and West Side areas susceptible to flooding.

There is a city program that has been slowly replacing traditional hard-surface alleys with so-called green alleys that are permeable and can hold water. The cost to reconstruct an alley is about $480,000, though that can vary. Almost 500 have been installed since 2007. More are expected this year, paid for with $20 million budgeted for 2026. Chicago has nearly 2,000 miles of public alleys that could be adapted.

There need to be more of these innovations, and they need to come fast, according to Neukrug and others.

Richard Fisher, former engineer in charge of stormwater management projects for the Metropolitan Water Reclamation District of Greater Chicago, spearheaded many of the almost 300 flood-control projects the district has worked on in just over a decade. They include large-scale projects as well as the smaller ones Neukrug talks about.

Formerly known as the Chicago Sanitary District, the government body that engineered and built the Deep Tunnel and once famously reversed the flow of the Chicago River away from Lake Michigan is now looking at green solutions to help flooding.

Fisher stands in a wide-open field in Glenwood, just west of Assumption Catholic Cemetery and Mausoleum.

It’s 800 acres. A square mile. Fisher sees a potential for wetlands that would be managed by the Forest Preserves of Cook County.

He estimates that the project would help reduce flooding for about 3,000 homes, from Calumet City to Dolton to Ford Heights, communities that have been ravaged by flooding.

Fisher describes it as “really managing the storm water where it falls,” which is a departure from the strategy of diverting floodwater to the massive reservoirs located in the suburbs.

The cost could be as much as $300 million. It’s not clear yet whether it will be feasible. The estimated time to complete the project could be 10 years or more.

But this type of solution won’t work everywhere. There aren’t 800 acres near Chatham, Austin and many other Chicago neighborhoods.

There’s also a need for traditional engineering projects along the lines of the Deep Tunnel project.

A proposal for another massive tunnel project, for the Far Southeast Side, is being considered by the city’s water management department. That project would connect with the Deep Tunnel. The cost is estimated at $1 billion, for which funding hasn’t been found.

Climate change is intensifying

With the dire prediction that rainfall in Chicago could increase by another inch by 2050, it’s important to take steps now, experts say. The rain won’t wait.

“We’re seeing climate change really move that goal post,” says Kate Evasic, lead planner for climate resilience for the Chicago Metropolitan Agency for Planning, the primary government planning organization for the Chicago area.

Evasic says the warning state officials sounded last year will be key to making decisions.

“We are in a better place,” she says. “But we’re having to account for the oversight and the mistakes that were made.”

Michael Wilson, who owns a home in Auburn Gresham, says he’s had flooding headaches for years. After flooding last summer, he had sewer water come up through his basement drains in January, leaving “a rotten smell” that “left a lot of dark mud and crud.”

Six years ago, he experenced flooding at another property he owns in Chatham. After that, he paid a contractor more than $12,000 to install a flood-prevention system that he says has worked to avoid additional problems.

“When it starts raining, I do get anxiety,” Wilson says. “I’m just trying to figure out the next step to prevent this problem from happening again. Hopefully, the city of Chicago will figure out a solution.”

This article was produced as a project for USC Annenberg’s Center for Health Journalism and Center for Climate Journalism and Communication 2025 Health and Climate Change Reporting Fellowship.