Illinois River Levels & Streamflow

As of August 21, 2026, Illinois rivers are running at 201% of normal across 153 USGS streamgauges, and the Mississippi River At Chester is reporting the highest discharge at 239,000 cfs. The full sortable gauge table is below.

As of August 21, 2026, the highest discharge in Illinois is 239,000 cfs on the Mississippi River At Chester. See the sortable gauge table for the full statewide ranking.

Compare the statewide percent-of-normal on this page: above 100% means Illinois rivers are running higher than the seasonal average for the date, below 100% means lower (a dry spell or drought). Each gauge also shows its own percent of median.

The U.S. Geological Survey National Water Information System. USGS streamgauges report continuously (every 15 minutes) and the data is the canonical real-time record for U.S. rivers. Snoflo pulls the latest readings and joins them to a 7-day NOAA weather forecast for each station.

Cubic feet per second — the standard unit for streamflow. One cfs is about 7.5 gallons per second. Small creeks run at single-digit cfs; the Mississippi at hundreds of thousands.

The water level at the gauge in feet above the reference datum. Used together with discharge to track river state. Flood stage and runnable levels are typically expressed in gauge height (e.g., "flood at 16 ft").

USGS streamgauges report every 15 minutes; Snoflo re-pulls throughout the day. The AI briefing regenerates daily.

Yes. Save any USGS gauge as a favorite in the Snoflo iOS app, set a discharge or stage threshold (e.g. "alert me when discharge crosses 2,000 cfs"), and you'll get a push the moment it crosses.

No. Snoflo is informational. For flood life-safety decisions always follow guidance from your local NWS forecast office and state emergency management. Snoflo data is one input among several.