Without a doubt, reading the water is among the most important skills a fly fisher can possess, yet among the most difficult to learn.Anyone can practice fly casting in the yard and eventually develop a beautiful cast but it's very difficult to learn the nuances of where trout position in the current without spending time on the water. We have videos planned that will clearly illustrate this, but we're so excited to share our knowledge we've put together a short post about the most important elements of reading the water.Foam Is HomeTrout will eat your fly because they are actively looking for food. If you know where to look for the trout food you're sure to find a fish that will eat your fly. Trout may be almost anywhere in a river or stream, but if they are in areas with little to no food they probably aren't interested in feeding. The most basic thing to know about reading the water is knowing where a fish will feed. Fortunately it's incredibly easy. In fact it's so easy that we can look at a river or stream from a fair distance and pick out areas where hungry fish will congregate.It's important to realize that trout live in a moving environment. Water is moving downstream 24 hours a day, 7 days a week, 365 days a year. It never stops. The aquatic insects trout eat also live in this environment. Some of these insects are better swimmers than others, but they are all swept by the current. Just imagine for a moment that you are swimming in the surf at the beach. Remember how you might throw a frisbee with friends or surf the waves on a boogey board? You moved around where you wanted to, but eventually you'd look up and notice your hotel was waaaayyyyyy up the beach from where you were. The tide or rip current swept you away even as you could move around where you wanted to.This is just the same with aquatic insect nymphs and larva. The currents will sweep them along and they are truly at the mercy of the currents as they move to the surface to hatch and complete their metamorphasis to a winged adult at the surface. Look at any river or stream and you will see drift lines of white bubbles. The bubbles aren't spread across the stream at random. They are funneled into well defined drift lines by the currents. Rock formations, boulders, and river banks all create obstacles for the current to flow around. These all create choke points where trout have food brought right to them. The thicker the line of bubbles is, the more food is funneled there and the more trout will be waiting there to find food.Charity hooked up with a nice fish in a drift line full of foam.The thickest drift lines will have so many bubbles as to look more like foam than mere bubbles. Just remember, foam is home for trout!Look for the sharp transitions in currentTrout must be very efficient if they are to survive. They can't grow if they burn more calories swimming in the current than they gain from eating. Adults will lose weight and eventually die if they expend more energy than they eat. Trout are instinctively in spots where they get the most food for the least effort. The best places to look for hungry trout is right on the edge of swift water, but not quite in it. This allows a trout to swim in easier, slower moving water while being right next to an area where more is moving past. That swift water will have more insects drifting downstream but the trout doesn't have to fight that extra swift water to get those morsels. He'll position himself on the slower edge and duck in and out of the swifter water as food comes along.Most anglers make the mistake of looking for the calmest water since they expect trout to sit somewhere that they won't need to fight current. The problem is that a trout doesn't get very much food if it remains in still water. In fact, it's less efficient for a fish to feed in calm water most of the time because he'll need to swim around looking for food. This is a problem for a fish because the most vulnerable nymphs are swept up by current. If there's no current to dislodge an insect from the rocks, there's not much food for a trout. Trout in calm water are rarely feeding.Charity fishes a nymph right along the edge of swift water. Notice how the water has been forced around the large boulder along with any insects in the current.Even though trout will burn up some calories swimming in the current they will eat far more calories in current than calm water. Look for those narrow zones right next to swift water, and of course the best spots will be marked with the white foam bubbles.Heads and TailsTrout will inhabit a variety of areas in a run of water, but two areas will often produce the most fish. The one zone that most anglers eventually figure out on their own is the head of a run where swift water or a set of rapids starts to slow down. Some anglers eventually figure this out on their own because they catch fish here most often. This is because the head of a run tends to attract the greediest trout.Trout are not team players; it's every fish for himself out there. The head of a run is highly desirable for a trout because this is where bugs will tumble into a pool from the rapids above. It's first come, first served so the most highly motivated fish will position themselves here. In fact, several fish will often try to jam into a spot like this and each knows that if he sees a bug he has to get it before any of his compatriots can. As a result these fish may take a fly without getting a very good look at it. They're main objective is to be the first to grab it. This makes them highly susceptible to a fly fisher's offering.A brook trout in position near the head of a run watching for insects in the current.Another valuable position in a pool, but one not recognized by as many anglers is the tail of a pool or run of water. Every pool is unique but many will empty into the next via a bottleneck that creates a funnel. In most instances this will be slower water than is found at the head of the run but the combination of current and a funnel make this extremely valuable real estate for trout. Sometimes the largest fish in a run will set up in this position. Larger fish are masters of efficiency and have little interest in fighting swift water only to have a smaller fish jump in front of them for every tidbit that comes along.Large trout have also dodged close encounters with predators in their life. Life out in the wild is dangerous and only the most paranoid survive. Have you ever heard someone comment about going in a bar for a drink and deciding it was a little rougher joint than they anticipated? The safest seat was with their back to the wall so they could keep an eye on those shady looking characters being rowdy up at the bar. That's the mentality of a large trout in the rear of a pool. No one can sneak up on him from behind and he can see the entire pool ahead of him. Even better all the food adrift in the run gets funneled to him.Now go use this knowledge and go out to the river to have some fun!