The Head of the Pool — An Easy Spot for Prospecting

Often the water is too deep for you to pick out individual rocks, or the rocks are too small to be differentiated from the characteristic marks on the surface. Even though trout will key in on certain rocks no bigger than themselves, and fish will lie on top of or just behind certain rocks year after year, no one has come up with a formula for predicting what rocks offer exactly the right hydraulics. I hope they never do. When you can't locate the rocks, you have to use other clues. The head of a pool or run is the first place I go, because the water there is faster than in the rest of the pool, so the fish will be easier to approach and fool. (I never told you we would always force ourselves to do this the hard way, did I?) Water coming into a pool, right in the tongue as it spills over whatever obstruction forms the head of the pool, may often be too fast to hold trout. Without a log or rock to block the current's force, this part of a pool may be sterile. Usually, though, as the current entering a pool starts to flatten and slow (typically just below the standing waves, if there are any), there will be a shelf, with an area of calm water below its lip. Here trout can hold in comfort and have the pick of the current. If you can tell me how to get to them in early spring, when there are four feet of raging current above them, then you should be writing this book instead of me. Once in a while, if you twist enough lead in front of a streamer, toss it above the pool, and strip just as it drops over the lip, you might draw one out of the maelstrom. But in the early season the water generally is too cold for a trout to chase anything moving faster than a crawl, so you're out of luck anyway. You can try those guys under the waterfall in midsummer, when the current barely whispers over their heads. There are easier places at the head of the pool.

In a fast bend trout may be found more often on the protected inside of the bend.

Look at the edges of the fast current on either side of the tongue, the place New Zealanders call the "eye" of the pool. If there is a bend in the river at the head of the pool, as there often is (do you know how hard it is to find a "classic" pool with mirror-image seams on either side?), there will be an inside and outside bend. Where most of the trout will be found depends on current speed. In fast current, where the water on the outside bend smashes against the bank, you'll find more trout on the inside. The outside may even be completely sterile. I once coveted a spot on a favorite trout stream where the current plowed up against the far bank, carving a dark undercut. I never saw a trout rise there and never hooked one blind­fishing, so I assumed there was a monster brown in residence. One steamy August day when even bobbing away in an inner tube looked inviting, I put on a diving mask and poked around. I was disappointed. Not only were there no trout in a place I had paid much attention to over the years, the bottom was as smooth as a beach pebble and offered not one place for a trout to get out of the current.

In a slow bend trout will be where the food flow is concentrated — on the outside of the bend.

On the other hand, if the current is so slow that leaves and other debris collect on the inside of the bend, you'll find more trout on the faster outside, where the meager current will bring them the most food. In streams with poor to average fertility you would expect to find trout where there is at least some current to bring them food, but in a rich river trout can be anywhere, including those neglected backwaters. Also, if the head of a pool is formed by a gentle riffle rather than a slick tongue of fast water, you'll find trout distributed all across the riffle, not just at the seams on both sides of the tongue.

Turbulence is what makes the head of a pool easier to fish. At the tail of a pool, and usually in the middle, the water velocity is stratified: faster water is at the top, where your fly enters, and much slower water is near the bottom, where the trout lie. When you cast a dry fly upstream in the tail of a pool, the water closest to you is accelerating before it dumps over into the next pool or riffle, so drag sets in almost as soon as your fly lands, making it move unnaturally.

At the head of a pool water velocity is more uniform in a vertical cross section; it stratifies in the middle and tail.

When you cast a nymph upstream, it starts to sink, but the leader and line on top of the water are moving faster, so they begin to pull the fly upward, keeping it out of the productive water below and, again, dragging unnaturally. Your choices include dumping a lot of slack into the cast when fishing a dry or nymph upstream, using a technique that is independent of the current, such as a streamer, or using a technique that uses current to your advantage, like a swung wet fly or a skating caddis. If you're unfamiliar with these techniques, don't worry; I'll describe them in later chapters.

At the head of a pool or riffle, though, turbulence mixes the currents so they're much less stratified. The downstream progress of the water is impeded, making it easier to slip a nymph through the currents or to get a drag-free float with a dry fly. And you can still swing a streamer or wet fly through these currents, so your options are doubled.

Riffles and Soft Spots

A plain, boring — and easy — riffle on the Bighorn. It's a real soft spot.

Plain, boring old riffles are some of the easiest and most productive places to blind-fish, because the way the water moves conspires against the trout. Current speeds seem uniform both vertically and horizontally: the many cells of turbulence are so small that they produce, for practical purposes, a uniform body of water, lessening drag on a dry fly or a nymph. Contrast a riffle, with its many tiny goose bumps of turbulence showing on the surface, to a boiling slick, where the turbulence cells are larger, big enough to grab your leader and wrench your fly. In a boiling slick the turbulence may even be strong enough to push a trout out of position constantly. Since trout like predictability, if they have to fight for position or they can't accurately take a piece of food, they'll move in a hurry. Unless I'm streamer fishing or I have seen a decent trout rising in them (which is seldom), I avoid boiling slicks like a bank full of worm fishermen.

Datus Proper, in his thought-provoking and iconoclastic book What the Trout Said, describes places he calls "soft spots." These are places where almost anything you do will produce a strike — places that Proper takes rank beginners to bolster their confidence. Every stream I fish has some soft spots, which I have found through experience, and I use them for special guests, children, and impatient or discouraged fishing buddies. All of the soft spots I know are in gentle riffles, lacking either strong whorls of current or the rooster tails of standing waves.

The result of fishing a nymph in that soft spot on the Bighorn.

A wide expanse of riffle, whether at the head of a pool or in a transition between pools, seems at first to have no features. Look harder. First you'll notice seams at the edge of the riffle, and these are worth much of your time and effort. Out in the middle of the riffle, look for slicks — areas that look as though someone polished and flattened the bumps on the surface. Slicks are formed either when the water is too deep for the turbulence formed by contact with the bottom to reach the surface, or when the water is slowed by a plateau in the streambed or an object on the bottom. If there is enough water, all of these places will hold trout. Depth is a limiting factor for trout abundance only when the water is so shallow that trout feel insecure about holding in it. In a riffle the water may be too shallow to hold adult trout, because as a rule they need to have a foot of water over their backs and a nearby refuge. So look for the places where the water is too deep for you to see the stones on the bottom clearly; when looking at slicks, make sure they are big enough or deep enough that a trout can find a place to hide when you stumble up through the currents. A slick the size of a kitchen sink in the center of a shallow riffle might offer all the food and protection from fast currents a trout needs, but a trout won't stay alive there for long unless the merganser population has flown south for the winter.

If you can find a slick the size of a bathtub with secure cover nearby, you may find a trout that everyone else has missed. I remember one place in a shallow riffle I must have walked through fifty times without a cast. There was an old dead tree trailing in the riffle, and at the downstream end was a tiny pocket, barely deep enough to cover my ankles. I stared and thought I could see bare stream bottom, but I cast a Gray Fox Variant anyway. A brown shape formed seemingly out of the gravel, rose to meet the fly, moved without apparent haste to the tangle of branches, and broke my leader. I have been back to the same place another fifty times and have not seen that trout again.

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