I use the USGS site almost every day. But since I started paddling more down around the Gulf Coast, I've had to learn some new truths about cfs and stream volume.
Up on the piedmont, and in the mountains, the cfs figure will often tell me whether a stream is big enough and deep enough to paddle. In most of Georgia, for example, if a creek or small river carries at least 300 cfs, it may be comfortable to paddle. A larger, wider river may need more cfs to cover the shallows and shoals. Another rule of thumb I use is that a creek with a 30 square mile watershed area (above the USGS gauge) may be negotiable after a heavy rain, but it's better to have a watershed area well over 100 square miles if you hope to find a stream that's runnable throughout the spring.
You can find watershed area for a particular gauge by going to the pull-down data menu for that stream and clicking on the "location". A wonderful selection of maps will come down, mouse-controlled. And above the map you should see the watershed area in square miles. I used to calculate watershed areas from topos I bought. Now I seldom have to.
Whether a stream has enough watershed area and current streamflow in cfs is knowledge you need to accumulate from experience. Use the USGS data to find out what streamflow you had on your last attempt to paddle a stream. You can often extrapolate from one stream to another, such as from Hatchet Creek to Weogufka in central Alabama. They are similar in size. Hatchet takes 600 cfs for a decent run, and if Hatchet is high enough, Weogufka should be also.
Back to the coast. Rivers with good flow, like the Bogue Chitto, obey roughly the same rules as piedmont and mountain rivers. Smaller streams like Coldwater in Florida probably do too. But I found that for bayous, which often have good channels but very slow flow, the USGS cfs figures do not predict runnability. A bayou might have a 30 cfs flow in a dry period, yet be big enough for outboards. Sometimes when the flow is low enough, the USGS gauge only reports gauge height, not flow, and that's just as well.
As someone quoted an army seargeant, it's the situation and the terrain.