With the Thornton Composite Reservoir near capacity for the first time in its history, south suburban residents are fearful of more flooding and some are sickened by the stench of sewage.
After the round of pouring rain that swept the suburbs over the weekend, the Thornton Composite Reservoir reached 94% capacity, the fullest it has been since becoming operational in 2015, according to the Metropolitan Water Reclamation District of Greater Chicago.
As of 10:15 a.m. Tuesday, the water level had receded slightly from that high to 93% capacity, or 7.3 billion gallons, according to the district’s website. The highest the reservoir has ever been before was in 2019, when it hit 54.5% capacity.
With billions of gallons of sewer water sitting open to the air, nearby residents have to deal with the stench.
“It smells,” said Thornton Village Clerk Nikki Kitakis. “It’s pretty horrific.”
Odors from the reservoir have been a long-standing issue for residents of Thornton, though Kitakis said the issue is particularly severe with the reservoir so full.
“The stench is putrid, and it affects all facets of life because it smells so terrible,” Kitakis said. “I wish there was Smell-O-Vision so I could send a sample your way because it’s, it’s awful.”
The water reclamation district has taken some measures to mitigate the stench, but it’s hard to adequately address a “quarry full of disgustingness,” she said.
“All we can do is wait and see, but in the meantime, it’s pretty disgusting,” Kitakis said.
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The water reclamation district said on social media it is “working around the clock” to pump down both the Thornton Composite Reservoir and the McCook Reservoir in southwest suburban Bedford Park, which serves central Chicago.
The Thornton reservoir takes in water from 14 communities, including Chicago’s Far South Side, Calumet Park, Dixmoor, Dolton, Harvey, Lansing, Markham, Phoenix, Posen, Riverdale and South Holland, an area with 556,000 people, and is the largest combined sewer reservoir in the world, according to the Metropolitan Water Reclamation District.
Those communities could face increased risks of overbank flooding and potential for combined sewer overflows if the reservoir hits capacity, the district warned.
In Dolton, residents shared their stories of flooding at Monday’s Village Board meeting. Mayor Jason House expressed empathy for “every loss of basement furniture.”
“I know there are many residents who cringe when it rains, and I promise you, I cringe with them,” House said.
He also emphasized relief will likely be slow, as a complete overhaul of the village’s flood infrastructure would require about $50 million.
Matt Stacy, who recently returned as the village’s public works superintendent, asked residents to “cross your fingers, say a couple prayers that we don’t get no rain for a little while.”
He said he was on the phone with the Metropolitan Water Reclamation District all day Saturday, concerned that the Thornton reservoir had nearly filled.
When meeting attendees brought up that more rain is forecast for this weekend, Stacy said that “hopefully, it blows the other way.”
Forecasts predict possible rain for the Chicago area on Thursday and Friday, with a lower chance on Saturday, according to the National Weather Service.
To drain the reservoir, the district allows water flow by gravity through a tunnel to the Calumet Water Reclamation Plant, 5 miles north of the reservoir, said Allison Fore, public and intergovernmental affairs officer for the district.
At the plant, 400 E. 130th St., Chicago, the district pumps water up about 300 feet to treat it, clean it and return it to the environment via the Little Calumet River, Fore said.
The reservoir holds 7.9 billion gallons of storage, Fore said. That means that at current levels, it still has room for about 600 million more gallons of water.
“The Thornton Reservoir still has some available capacity, but it is significantly reduced because of the recent storm event,” public affairs specialist Patrick Thomas said in an email. “Whether the system can handle additional rainfall depends on the amount, intensity, duration, and location of the rain, as well as the level of the reservoir and tunnels at that time.”
Thomas said the district can’t provide a timeframe for when the water will be treated and drained.
“The timing depends on additional rainfall, incoming flows, tunnel levels and treatment plant conditions,” Thomas said.
He also encouraged the public to report odors by calling 800-332-3867.