The Meaning of Water
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Rapids, Runs and Riffles:
I distinguish riffles from rapids from runs by the depth of water. Runs generally lead to rapids and rapids to riffles to pools or vice versa depending on how you look at it. The turbulence in riffles and rapids are caused from subsurface rock structure, while runs may be shallow with little resistance or the water too deep for sub-surface structure to disturb it.
Often long runs of fast moving water will hold few fish or simply be too fast to fish effectively. But if you look for larger rocks and flat spots, the places where a submerged tree or stone has created an area of calmer water chances are it will hold fish. Trout will occasionally move in and out of the fast water to hijack passing insects and other food items and if there is a rock big enough to cover and protect the trout, then it’s a good spot to prospect a fly.
Shallow or quiet runs usually occur after deeper or faster water. The shallow gravelly areas of a stream are where most aquatic insects and fry emerge and thrive. On most streams you can see evidence of mayfly and stonefly nymphs as their empty husks cling to streamside stones or the cocoon like shell of a caddis fly attached to the underside of rocks or moving slowly about the shallows.
Trout usually feed alongside or downstream of these areas during the day, but in the evening when these aquatic insects turn into their adult form, the hatches can be thick and trout will move into these ‘flat’ areas aggressively feeding on the emerging adults.
The head or tail of a pool is usually a riffle or rapid that often holds many trout. Riffles are used as forage areas and can be very productive because of the excellent light penetration and clean, well aerated gravel, which provides valuable habitat for many fish-food invertebrates.
These are prime areas for trout; however, tailouts tend to hold bigger trout on average. It only makes sense really. If I were a trout, I’d go where there was the most abundant food supply, in a good current with a nice view of the pool in front of me. Kind of like a poolside restaurant at a fancy resort. The pool affords trout an unobstructed view of incoming insects as they are funneled into the tailout.
The water flowing into the tailout gets faster and shallower so the best place for holding trout is at the edge of the pool just as the darker deeper water turns to the lighter shallower water. Also, as the rate of the current increases through the tailout, look to the edges of the banks or debris that creates natural eddies and cover for trout.
Pocket full of trout:
Pocket water is probably the most overlooked and underappreciated holding area for trout. They are often inconspicuous bumps in a run or riffle, a submerged rock or a pile of smaller rocks between the size of a melon and a beach ball. As water rushes over a submerged rock, resistance creates turbulence caused by the difference in fast and slow water. If the current is flowing too strong it will create white water, too much turbulence, and boulders won’t make for good trout holding zones. However, in moderate flows or peripheral areas of the stream where the current is not so torrential, you will find trout holding in the relative comfort of the rock’s shadow.
As the water passes over or around the rock it creates a pocket of slack water, with currents fl
owing around either side. Depending on the size of the obstruction, the length and depth of the slick will vary. The narrowest part of the ‘V’ created by the current flowing over the rock is where trout will most likely hold, gobbling up offerings from either segment.
These are trout havens, as they often afford good hiding spots from a passing osprey as well as a constant supply of food. However, unless you intend to stack a lot of line, avoid placing a fly directly behind a large rock where the current piles up. The kinetic energy of the water will create immediate drag and probably spook the fish. Better to float or drift your offering through the nearest seam or close to it.
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