Chicago Unveils Stormwater Unit as McCook Reservoir Hits 3.6 Billion Gallons
Updated
Updated · NBC Chicago · Jul 7
Chicago Unveils Stormwater Unit as McCook Reservoir Hits 3.6 Billion Gallons
3 articles · Updated · NBC Chicago · Jul 7
Summary
MWRD and Mayor Brandon Johnson on Tuesday unveiled a new wing storage unit near Central and North avenues on the Far West Side to hold excess stormwater after recent rains strained Chicago’s flood system.
3.6 billion gallons now fill the McCook Reservoir, while the Thornton quarry is more than 90% full, pushing the region’s Tunnel and Reservoir Project close to its limits.
13 billion gallons of stormwater were captured in the past week, and MWRD says it is pumping more than 600 million gallons a day back into the system for treatment.
2026 has already filled McCook six times, compared with five times in all of 2021-2025, a surge officials link to heavier, more frequent rain and a rising overflow risk.
A 50-year, $3 billion-to-$4 billion Deep Tunnel system is still holding for now, but MWRD is urging household water conservation and building another 6 billion gallons of McCook capacity.
With Chicago's flood system failing, why are hundreds of millions in federal disaster funds from 2023 still unspent?
As basements keep flooding, are costly home retrofits the only real defense against Chicago's overwhelmed sewer system?
Chicago's Deep Tunnel was built for a past climate. Can green infrastructure really protect the city from future superstorms?
2026 Chicago Floods Expose Limits of Deep Tunnel System and Drive Citywide Green Infrastructure Overhaul
Overview
In the summer of 2026, Chicago faced severe rainfall, especially during the July 4th weekend, leading to widespread basement and street flooding on the West and South Sides. Earlier in the year, heavy spring rains and flooding along the Des Plaines River had already strained the city’s infrastructure. With soils saturated and reservoirs nearly full, even moderate rain now poses a high flood risk. The McCook Reservoir reached capacity more often than ever before, highlighting the growing pressure on Chicago’s flood defenses and the urgent need for both immediate and long-term solutions.