The Metropolitan Water Reclamation District reported that McCook Reservoir in the Chicago suburbs rose to 97 percent of its capacity on Tuesday, August 11, 2026, after a bout of heavy rain and strong winds. The increase represents a two‑percent gain from the previous night’s level and places the reservoir just shy of full storage.
The district’s monitoring network shows that the storm‑water system’s other key reservoirs experienced varied changes. Thornton Reservoir, also serving the region, held about 57 percent of its capacity, while Majewski Reservoir recorded no water, remaining at zero percent. These figures illustrate the uneven distribution of runoff across the district’s infrastructure during the same weather event.
The storms that moved through the Chicago area on Tuesday delivered intense precipitation and gusty conditions, prompting rapid inflow into the storm‑water basins. The district’s real‑time data collection tracks such fluctuations to manage flood risk and maintain water quality. The rise in McCook’s level reflects the basin’s ability to capture runoff from the surrounding suburban landscape.
Officials from the Metropolitan Water Reclamation District continue to observe reservoir levels as the weather system moves eastward. While McCook approaches full capacity, the district maintains that current storage remains within design limits and does not pose an immediate threat of overflow. The agency’s ongoing assessments will determine whether any operational adjustments are needed to accommodate further rainfall in the coming days.