Where the water stands right now against the four official thresholds:
| Flood stage | Level (ft) | What it means |
|---|---|---|
| Action stage | 491 | water is approaching flood level — time to pay attention |
| # | Crest (ft) | Date | vs. minor flood stage |
|---|---|---|---|
| 1 | 506.44 | 2020-05-18 | — |
| 2 | 506.38 | 2013-04-19 | — |
| 3 | 506.35 | 2008-09-15 | — |
| 4 | 505.7 | 2018-02-22 | — |
| 5 | 505.23 | 1982-12-04 | — |
| 6 | 504.7 | 1957-07-14 | — |
| 7 | 504.5 | 1990-11-29 | — |
| 8 | 504.29 | 1997-02-22 | — |
| 9 | 503.5 | 1985-02-24 | — |
| 10 | 502.87 | 2007-08-25 | — |
| 11 | 498.89 | 2017-05-02 | — |
| 12 | 495.02 | 2017-07-23 | — |
Historic crests recorded at this gauge by the National Weather Service — the 12 highest on file.
The marker is this gauge; nearby gauges load live and are clickable.
The live reading at the top of this page answers that: the gauge is compared against its official NWS flood stages every 15 minutes. Blue means normal, yellow is action stage, orange minor, red moderate and dark red major flooding.
action stage 491 ft. These are official National Weather Service thresholds set specifically for this gauge, not generic values.
The highest crest on file at this gauge is 506.44 ft, reached on 2020-05-18. The full list of the highest crests is in the table on this page.
From the NOAA National Water Prediction Service, the official U.S. river gauge network — a U.S. government work in the public domain. Live stage is refreshed every 15 minutes; flood thresholds and historic crests are refreshed monthly. For life-safety decisions follow NWS Romeoville and local emergency management.