Low water, which typically is accompanied with clear water, often provides challenging fishing conditions. Fish are often spooky, as these conditions make them more vulnerable to their predators.

But you can learn a lot about a body of water or flowing river by fishing them when they are low. Finishing up what has been a hot, dry, nearly-drought-like summer, there have been plenty of opportunities to learn.

Armstrong County’s Keystone Lake — which I’ve fished several times in recent weeks — is a good example. Currently the lake is about nine feet below full pool. Significant drawdowns occur on Keystone during dry years, as the incoming water sources are small. Couple that with elevated power needs (example: air conditioners) during an excessively hot summer — which translate into added water demands for cooling towers — and its water level drops considerably.

While getting your boat in and out of the Atwood ramp is more of a challenge, once on the lake a person can really see things that are usually covered with water. This includes old road beds, bridges (in tributary bays), stump fields, rock piles and brushpiles.

The upper tips of submergent vegetation are also up on the surface. In Keystone’s clear waters weeds grow out to depths in the 12 to 15- foot range (depending on where you are on the lake). When the lake stays full few weeds reach the surface, even by late summer. With the level down, though, weedlines are right on top, creating a visible outline of major structures, as well as well-defined targets to cast toward.

Keystone has a lot of shale banks. As the lake recedes, shelves are formed along these banks by wave action, particularly when the level stays at a given point for some time. When the lake fills back up these ledges are now underwater— providing ambush points for species such as smallmouth bass — along what was pretty much a featureless bank.

All of these details can easily be logged by taking a few shots with a camera, or even a short video, both of which can easily be accomplished with today’s smartphones. A short description entered in a written log, or computer file, ups the chances of the information being useful the following year.

Low water is not only helpful on drawn-down lakes, but on flowing waters as well. This is especially true on medium to larger sized streams and rivers; smaller streams often become a mere trickle during low water, with all fish concentrated in the deeper pools, which are the only places with enough water to support them.

But on larger flowing waters like the Conemaugh, Kiski, Clarion, and the middle Allegheny, fish holding character becomes much more visible as levels drop. When flows are higher such areas are simply buried under the higher flow.

Free-flowing rivers in this part of the country follow a riffle-run-pool sequence, based on surrounding topography of the area they drain. Fast riffles give way to runs, where the current is somewhat slower, and the water deeper. Runs eventually become pools — deeper and slower yet. At some point the pool will begin to thin out (commonly called the tail-out section), speeding up and then spilling into the next riffle, which starts the sequence again. On medium-sized streams like Mahoning Creek this can all take place within a couple hundred yards, whereas on the Allegheny it can take miles for the same transitions to occur.

When the water is low, riffles and runs become much easier to identify. And as you fish these waters, the small little details, such as a rock ledge within a run, or a fish-holding weed bed growing in a tail-out, become evident. Fish a flowing water long enough and you’ll come to learn which areas are most likely to produce fish given the flows of the day.

Jeff Knapp is an outdoors columnist for the Butler Eagle.