Water Levels/Floods/Gauges
This site gives the best information about water levels/gauges for the entire Rock River and some of its tributaries.
http://www2.mvr.usace.army.mil/WaterControl/new/layout.cfm
This site is very good information about water levels/gauges for the Rock River just in Illinois:
http://waterdata.usgs.gov/il/nwis/current/?type=flow
This site is good information about water levels/gaugesfor the central Rock River and as an overall site for the river:
http://www.americanwhitewater.org/content/River/detail/id/10167/#tab-flow
Another river gauge
http://water.weather.gov/ahps2/glance.php?wfo=mkx&gage=wpnw3&riverid=203217&view=1,1,1,1,1,1,1,1&toggles=10,7,8,2,9,15,6
Rock River reporting stations for Wisconsin and Illinois can be selected from the US Geological Survey site, USGS Current Water Data for the Nation
http://waterdata.usgs.gov/nwis/rt