Chicago Urges Water Cuts as McCook Reservoir Reaches 95% Capacity
Updated
Updated · NBC Chicago · Aug 10
Chicago Urges Water Cuts as McCook Reservoir Reaches 95% Capacity
3 articles · Updated · NBC Chicago · Aug 10
Summary
An Overflow Action Day was declared for Monday as Chicago-area residents were told to delay showers, laundry and dishwashing with more storms expected to bring several more inches of rain.
McCook, the region’s key TARP reservoir, is already 95% full with nearly 5 billion gallons, while Thornton stands at 58%, leaving less room for runoff and wastewater.
If the Deep Tunnel system fills further, officials warn of basement and neighborhood flooding, sewage overflows into rivers, and possible releases of untreated water into Lake Michigan that could trigger beach closures.
The strain has intensified this year: McCook has already hit capacity six times in 2026, compared with five times in the previous five years combined.