Will Cook County News

By Claude Martinez.

Thornton — After heavy rainfall during the Fourth of July weekend, the Thornton Composite Reservoir filled with a staggering 7.3 billion gallons of stormwater.

The Village of South Holland wrote in a Facebook post on July 6 that “the Thornton Composite Reservoir (the Quarry) is now 94% full, holding an incredible 7.3 billion gallons of stormwater. That’s the fullest it has been since opening…”

This was not always the case. “The Metropolitan Water Reclamation District of Greater Chicago (MWRD) completed the reservoir in 2015 as part of the Tunnel and Reservoir Plan (TARP), also known as the “Deep Tunnel,” wrote MWRD. “Its sheer size has helped nearly eliminate combined sewer overflows (CSOs) by collecting this stormwater and sewage before it can be conveyed to the Calumet Water Reclamation Plant five miles north to be transformed into clean water and released into the Little Calumet River.”

The reservoir can hold up to 7.9 billion gallons of stormwater and reach a depth of 500 feet in certain spots. With it now at 94% capacity, the system is helping reduce flooding and prevent combined sewer overflows throughout the south suburbs.

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