Rivers in Illinois
Mainstream Deep Tunnel at McCook Reservoir
Below flood stage
-178.53ftStage
Observed Tue, Sep 29, 6:00 PM CDT
- Flood stage
- -30.00 ft
- Record crest
- -33.70 ft2026
Flood stages and impacts
| Category | Stage |
|---|---|
| Minor flood | -30.00 ft |
| Action | -100.00 ft |
- -22.00 ftLowest rim of McCook Reservoir.
- -40.00 ftMcCook Reservoir reaches 100 percent of full storage. Combined sewer overflow event likely in central Cook County. Water remains contained within the reservoir.
- -95.00 ftMcCook Reservoir reaches 75 percent of full storage. Combined sewer overflow event possible in central Cook County.
- -155.00 ftMcCook Reservoir reaches 50 percent of full storage.
- -215.00 ftMcCook Reservoir reaches 25 percent of full storage.
- -280.00 ftMcCook Reservoir is empty, 0 percent of full storage.
Crest history
16 crests on NOAA’s list since 2018.
| # | Date | Stage |
|---|---|---|
| 1 | April 16, 2026 | -33.70 ft |
| 2 | July 6, 2026 | -34.50 ft |
| 3 | April 5, 2026 | -35.00 ft |
| 4 | May 6, 2019 | -35.40 ft |
| 5 | August 12, 2026 | -36.00 ft |
| 6 | August 19, 2025 | -36.60 ft |
| 7 | May 20, 2019 | -38.40 ft |
| 8 | May 23, 2018 | -38.50 ft |
| 9 | May 1, 2020 | -38.60 ft |
| 10 | May 21, 2020 | -38.90 ft |
| 11 | June 25, 2026 | -39.10 ft |
| 12 | October 30, 2021 | -39.80 ft |
| 13 | July 16, 2024 | -40.70 ft |
| 14 | August 2, 2026 | -40.80 ft |
| 15 | July 4, 2023 | -42.60 ft |
| 16 | July 2, 2021 | -44.00 ft |
Most recent crests
- August 12, 2026: -36.00 ft
- August 2, 2026: -40.80 ft
- July 6, 2026: -34.50 ft
- June 25, 2026: -39.10 ft
- April 16, 2026: -33.70 ft
- April 5, 2026: -35.00 ft
- August 19, 2025: -36.60 ft
- July 16, 2024: -40.70 ft
- July 4, 2023: -42.60 ft
- October 30, 2021: -39.80 ft
Nearby
Upstream, downstream and the gauges around this one.
What this means
Forecasts by the North Central River Forecast Center. Forecasts are issued as needed during times of high water, but are not routinely available. River forecasts for this location take into account past and future precipitation. The stages/flows that will occur may be different if future rainfall is different than forecast.
Sources
Stage, flood stages, impacts and crest history from NOAA’s National Water Prediction Service.