Illinois flood information from USGS and NOAA
Courtesy of Emily Wild, USGS librarian and scientist:
USGS news release: USGS Measures Record Flooding in Illinois
USGS Flood information, National, or select state of interest, e.g. Illinois
These two web sites show the same data: USGS and NOAA. When it comes to forecasting the river data, NOAA takes over the data interpretation.
Be safe out there if you are near a high river with Flood Safety Information.