The biggest obstacle I had to overcome when I first started fly fishing was being able to successfully “read the water” – i.e. being able to predict the areas where trout hold in streams. Years of bait fishing for catfish and largemouth, and tossing Texas-rigged watermelon Yamasenko worms into deep creek holes for smallmouth had created a pattern of mind-numbing repetition that left me clueless when it came to trout fishing. My previous experience told me that fish held in deep pools (which is only partly true). So for a long time, I would hop from one deep pool to the next, skipping all the water in between. Needless to say, I passed up on a lot of fish in those early days. It wasn’t until I ran into another fly fisherman nymphing a riffle, that I started to learn more about trout holding areas.
As most trout bums know, trout behavior and survival is largely dependent on water temperature. In water temps below 45 degrees, the trout become lethargic and don’t feed very often and usually hold in slow, deep pools. As water temps rise in the spring, the metabolism of the trout increase. In water temperature between 68 and 70 degrees, the fish will still actively feed, but they will generally hold in broken/fast water because of the higher oxygen content. If the water stays between 50 and 65 degrees, and there is adequate food, trout can be found in all types of stream environments – pools, riffles, runs, and pocket water. Water above 70 degrees is dangerous for trout, and trout struggling in these water temps should probably be left alone. If the trout have any hope of surviving the high temps, they need all of their energy reserves and the added stress of being caught by a fisherman will likely be fatal.
In faster water, objects like large rocks or trees obstruct the current and slow it down via friction. Where the current meets the object, an area of slow, slack water will form on all sides of the object, allowing a place for aquatic insects to gather without being knocked downstream by the current. It also provides a place for a trout to rest out of the current, and close to a food source. Pocket water, which is fast water with a lot of obstructions creating heavily broken surface water, can be extremely difficult to fish, but it can also hold a boat load of trout.
On the flip side, areas that appear to lack adequate cover, such as long, flat pools, can be very productive during a heavy hatch because it is easier for the fish to spot and intercept insects on the surface in slower water.
Don’t make the same mistake I did when I first transitioned to fly fishing for trout – don’t be a one dimensional fly fisherman. Use your knowledge of trout survival (water temps), trout food sources (hatches/aquatic insects), and stream characteristics to make educated guesses on where you should target. I think you will find an increase in the number of trout brought to net (coming from a guy who spent years throwing casts to the wrong areas!). And remember, there is no substitute for time spent on the water. Get out on your favorite stream and experiment!
Robert Fravel grew up in Pennsylvania, where he started fishing local streams and lakes at a very young age. During his college years, Robert spent the summers working as a whitewater rafting guide in the Pocono Mountains of northeast Pennsylvania. As an avid fly fisherman and fly tier, he enjoys exploring backcountry streams in search of untouched wild trout waters. He currently works as a lawyer in Dublin, Pennsylvania.