MWRD Storm Report 11 AM

The past weekend saw another round of severe storms hitting the Chicagoland area. The rain only added to what has already been a wet year.  The MWRD rain gauge at the Calumet Water Reclamation Plant had 3.77 inches of rain for this storm alone. 

The MWRD operates the Tunnel and Reservoir Plan (Tunnel and Reservoir Plan (TARP) | MWRD), which consists of giant underground tunnels and reservoirs that capture and capture and store stormwater until it can be treated at the water reclamation plants. The MWRD currently has over 13 billion gallons of stormwater in the deep tunnels and reservoirs that has been captured during multiple waves of storms. As soon as possible after the storms end, we begin dewatering TARP and cleaning that water at our water reclamation plants to make room for the next storm.  

The Thornton Composite Reservoir is currently 94% full, with 7.3 billion gallons captured in the reservoir, which is the fullest it has been since becoming operational in 2015.  Prior to this summer’s storms, the high-water mark was approximately 54.5% full back in 2019.  

The McCook Reservoir reached capacity on July 3 for the sixth time this year.   For context, the McCook TARP system filled 5 times cumulatively between 2021 and 2025.

Applications are now open for municipalities and local government entities to partner with the MWRD on four stormwater management programs designed to mitigate community flooding throughout Cook County. More information can be found at mwrd.org/stormwater/partnerships.

Visit these links for more information about the MWRD, Stormwater Management, TARP and how to help reduce flooding and protect water quality.