As torrential rain completely soaked parts of Chicago on Sunday morning, basements and partially submerged streets were not the only things that got flooded. Inbound calls poured into the city’s nonemergency system, 311.
More than 1,400 complaints — of “water in basement” or “water on street” — were logged on Sunday, and there were more than 700 the following day. Most were concentrated on the city’s Far Northwest and Far North sides.
One in four of the complaints came from Portage Park.
West Ridge, Edgewater, Albany Park and Lincoln Square had the next highest volume of complaints.
The West Ridge neighborhood received more than 4 inches of rain, according to data from the National Weather Service. North Center got just over 3 inches. Meanwhile, O’Hare and Midway airports got 1.95 and 1.40 inches, respectively.
The rain fell unevenly on Sunday, inundating some areas with intense downpours while sparing others, which explains, in part, why 311 service requests spiked in some neighborhoods and not others.
On May 17, 2020, a similar rainstorm swept through Chicago, flooding the Chicago River and leaving several swaths of the city waterlogged. 311 received nearly 1,800 complaints about water rising in basements or collecting on the streets that day.
The highest volume of requests came from communities throughout the city, particularly from the Northwest Side. The five leading communities were Austin, then Portage Park, Washington Heights, Belmont Cragin and Logan Square.
When residents file a complaint about a flooded street with the address of the incident and the location of the water — in the middle of the street, on the curb or in an alley — 311 then dispatches a sewer crew, according to the 311 website.
The complaint data is one of the inputs the Department of Water Management uses to determine where to improve portions of the city’s sewer system.
But not everyone calls 311 when issues arise. Some Chicagoans might not know the service exists, while others might choose not to call 311 because they don’t think it’ll be helpful to them.
Still, 311 data is one of a few data sources available that can help researchers and the city understand, broadly, the severity of storms and where they occur, said Ryan Wilson, manager of water resources at the Metropolitan Planning Council.
“Flooding happens as a result of rainfall which can be very erratic, from neighborhood to neighborhood or even block to block, and the amount of water that goes into our sewers and potentially back into our basements is really hard to predict, much less track,” Wilson said.
For Wilson and his team, 311 calls are a good way to understand how intense a rain event was, but not necessarily who was most impacted.
“That’s a very different problem when we think about equity, infrastructure and distribution of flooding impact. That’s not something where 311 data tells a really clear story,” he said.
Charmaine Runes is WBEZ’s data/visuals reporter. Amy Qin is WBEZ’s data reporter.
