One very important tool for the river smallmouth bass fisherman is the USGS River Gauges. Simply find the river where you intend to fish, find the gauge closest to where you intend to fish and check the gauge height or flow speed CFS (cubic feet per second).
Here is a graph that shows this stream at about 780 CFS:
CFS and gauge height match. For example at 5.2'high, the CFS will always be 780 CFS and so on. Pick one to remember or write in a log somewhere. It will be your note keeping which helps you be informed when to fish most effectively. Getting out on the stream and observing are still key. You need to have a mental image of what it looks like at that height. In comparing different streams, 780 CFS may be low for Giant River A, but for Creek B is a blowout condition. All depends on the size of the stream.
Here is the corresponding graph that shows the gauge height in feet:
This graph shows a gauge height of about 5.2'. Up more than 2' in the last couple days of rain. This means the creek is probably muddy. Of course, there are other factors. You can find streams with little surrounding loose soil that rise with very little turbidity.
Keep in mind, the gauge height does not pertain to actual depth on the river. It will give you an idea how much above or below average the flow height is. If you study these charts often, then you can compare what a comfortable fishing height is to you.
Even though the creek is up 2', if it normally runs very clear and has great surrounding habitat, you may find very fishable areas during high water. High water tends to push bait fish towards shoreline eddies and so the smallmouth bass. Big fish can be caught at times when they'd be hard to target in summer low water periods. Problem is usually one of visibility. The fish are right at your feet along the bank. Another factor, is how long since a rain event. Water can be high but clear because the rain was from several days previous.
Not all rivers and creeks have gauges. In this case, look at the closest river or creek for an idea of rise or fall of your target river.
Studying and logging your river gauges will help you avoid danger on the water and fish the conditions you want to fish. Reading and having a record of many different streams will help ensure you find somewhere to fish on those precious weekends.