Skip Navigation Link  
NOAA logo - Click to go to the NOAA homepage National Weather Service NWS logo - Click to go to the NWS homepage
Advanced Hydrologic Prediction Service
Image background of Navigation bar Left
Bookmark and Share Navigation Bar End Cap


Web Portal Changes:

  • AHPS - Scheduled operations ends on Tuesday, May 28th, 2024
  • Please see it NOW!  The pages will automatically redirect to until May 28, 2025.
  • To go to a specific gauge location  - use - where NWSLI is the five character ID of your favorite location.
  • Other Important URL changes - Service Change Notice 24-29 

Please visit for more information.

Hydrograph River at a Glance Download
Mainstream Deep Tunnel at McCook Reservoir Stage (ft)Observed: -240.44 ft at 7:00AM May 19, 2024Observed: -247.71 ft at 7:00AM May 21, 2024Observed: -250.03 ft at 7:00AM May 22, 2024Observed: -252.65 ft at 7:00AM May 23, 2024Metropolitan Water Reclamation DistrictMCCI2(plotting HGIRZ) Graph Created (11:55PM May 23, 2024)ObservedLatest observed value: -252.65 ft at 7:00 AM CDT 23-May-2024.
Printable Image
About this graph
Tabular Data (UTC)
Tabular Data (CDT)
XML Data
RSS Files
Datum: NAVD88
NOTE: Graphical forecasts are not available for the Mainstream Deep Tunnel at McCook Reservoir. During times of high water, forecast crest information can be found in the text products.
Return to Area Map
Downstream Gauge Downstream Gauge - at Lemont
Flood Categories (in feet)
Not Available

Historic Crests
(1) -35.00 ft on 05/06/2019
(2) -38.90 ft on 05/21/2020

(P): Preliminary values subject to further review.

Recent Crests
Currently none available.

Low Water Records
Currently none available.
Zoom Level:16
KML Image
Gauge LocationGauge Map Marker
Latitude/Longitude Disclaimer: The gauge location shown in the above map is the approximate location based on the latitude/longitude coordinates provided to the NWS by the gauge owner.
Flood Impacts & Photos Collapse
If you notice any errors in the below information, please contact our Webmaster
-40 McCook Reservoir reaches 100 percent of full storage. Combined sewer overflow event likely.
-95 McCook Reservoir reaches 75 percent of full storage. Combined sewer overflow event possible.
-155 McCook Reservoir reaches 50 percent of full storage.
-215 McCook Reservoir reaches 25 percent of full storage.
-280 McCook Reservoir is empty, 0 percent of full storage.
About This Location Collapse

Latitude: 41.777500° N, Longitude: 87.836600° W, Horizontal Datum: NAD83/WGS84

River Stage
Reference Frame
Gauge Height Flood Stage Uses
NWS stage 0 ft Not Available Interpreting hydrographs and NWS watch, warnings, and forecasts, and inundation maps
Vertical Datum Elevation
(gauge height = 0)
(gauge height = flood stage)
Elevation information source
NAVD88 579.20 529.20 Survey grade GPS equipment, FEMA flood plain maps, newer USGS topographic maps
NGVD 29 579.48 529.48 Older USGS topographic maps, NGVD29 benchmarks
MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks
Other 0.0 -50.0 Chicago City Datum
Additional Information Collapse
McCook Reservoir Webcam
TARP Reservoir Storage Levels
Resources Collapse
Hydrologic Resources Additional Resources
Collaborative Agencies Collapse
The National Weather Service prepares its forecasts and other services in collaboration with agencies like the US Geological Survey, US Bureau of Reclamation, US Army Corps of Engineers, Natural Resource Conservation Service, National Park Service, ALERT Users Group, Bureau of Indian Affairs, and many state and local emergency managers across the country. For details, please click here.
NWS Information
National Weather Service
Chicago Weather Forecast Office
333 W. University Dr.
Romeoville, IL 60446
(815) 834-1435
Ask Questions/Webmaster
Page last modified: 30-Oct-2020 4:09 PM
Privacy Policy
About Us
Career Opportunities