Thornton Reservoir Near Capacity Raises Concerns of Flooding and Odor

The Thornton Composite Reservoir has reached an unprecedented level of capacity, creating concerns for residents in the south suburbs. Over the weekend, heavy rainfall pushed the reservoir to 94% capacity, the highest since it became operational in 2015, according to the Metropolitan Water Reclamation District of Greater Chicago. As of Tuesday morning, the level slightly decreased to 93%, or 7.3 billion gallons.

Previously, the reservoir’s highest recorded capacity was 54.5% in 2019. The large volume of exposed sewer water is causing severe odors, affecting local residents. Thornton Village Clerk Nikki Kitakis describes the smell as ‘pretty horrific’ and says it impacts daily life. Despite efforts by the water reclamation district to reduce the smell, challenges remain.

The district is continuously working to manage water levels in both the Thornton Composite Reservoir and the McCook Reservoir. These reservoirs serve regions including Chicago’s Far South Side and several communities, accommodating a population of 556,000 people. Risks of flooding increase if the Thornton Reservoir reaches full capacity.

In Dolton, residents shared experiences of flooding at a recent Village Board meeting. Mayor Jason House empathized with those suffering property loss due to flooding, acknowledging the high cost of infrastructure improvements needed for flood relief. Public Works Superintendent Matt Stacy advised residents to hope for minimal rain in the coming days.

With forecasts showing potential rain later in the week, concerns persist. A rain gauge in Flossmoor recorded over six inches of rain from the recent storms. Current draining of the reservoir involves using gravity-fed tunnels to the Calumet Water Reclamation Plant, where water is treated and returned to the Little Calumet River, according to Allison Fore, an officer with the water reclamation district.

The Thornton Reservoir has capacity for 7.9 billion gallons, leaving space for about 600 million gallons more at present levels. The water reclamation district did not offer additional comments on how long draining might take.