If you repeatedly paddle the same river and keep track of the gauge readings, you will soon develop a good feel for what a given flow rate means in terms of volume and current velocity.
The USGS gauge for the Kankakee at Shelby, IN reports here:
http://waterdata.usgs.gov/in/nwis/uv?site_no=05518000
Note that the flow data graph also gives you median flow rates for the same dates in the past. Some USGS gauging sites also provide water temperatures.
In addition to checking the Shelby gauge, it is a good idea to check upstream gauges, particularly during or immediately following periods of heavy rainfall. This will give you an idea not only of what the river is doing at Shelby, but what it is likely to do in the immediate future. In this case there is a USGS gauge at Dunn's Bridge, IN:
http://waterdata.usgs.gov/in/nwis/uv?site_no=05517500
Typically, rivers gain volume as the flow downstream gathering tributaries so generally, the flow rates will increase as you look at gauge readings progressively downstream. This may not be true for rivers impounded by dams if the amount of water flowing into the reservoir is less than what is being released at the dam. It may also not be true for rivers in which large volumes of water are being withdrawn for water supplies of large cities or for agriculture. An example is the mighty Colorado River which is sucked dry before it reaches the Gulf of California. Another example is the Delaware River which has such large volumes diverted into reservoirs by New York State to supply drinking water for NYC that there is a potential risk that the brackish water of the Delaware Bay estuary could back up sufficiently to contaminate the water supply for Philadelphia.
In the case of the Kankakee there are no large tributaries between Dunn's Bridge and Shelby and nobody appears to be sucking the river dry, so the flow rate at Shelby (1800 cfs) is only a little greater than at Dunn's Bridge upstream (1400 cfs). If you look at the next gauge downstream at Momence, IL you find that the river has picked up a fair bit of volume (2270 cfs):
http://waterdata.usgs.gov/il/nwis/uv?05520500
Note that the stage of the river at Momence is 2.46 feet, the stage at Dunn's Bridge is 5.12 feet but the river has more than half again as much volume flow at Momence as at Dunn's Bridge.
During periods of heavy rain a river will typically rise first at its headwaters. The stream bed is physically smaller there so the stage will typically rise more quickly and much more dramatically than it will further dowstream. By watching the upstream gauge during and following rains and comparing it with the Shelby gauge you will develop a feel for how long it takes for a rise in the river upstream to be reflected at Shelby, and how much precipitation it takes to produce a given rise in the river.