A good nymph fisherman is like a sharpshooter that applies all focus to their target and ignores everything else. Unfortunately, many anglers use more of a shotgun approach when wade fishing and try to scour a creek or river by spraying casts in every direction. Many fly fisherman quickly begin to learn that most trout occupy a small percentage of a river, choosing to remain in the most productive zones such as seams, riffle corners, and riffle drops. Even when anglers recognize the best holding water in a river, I have noticed that few fisherman consistently use the correct casting distance for specific situations when nymph fishing.
Casting distance and angles are one of the most components of a good presentation. Many fishermen mistakenly assume that they are adequately covering good trout water by simply having their flies in the feeding lanes. The reality is that the geometry of a cast has a lot to do with a good presentation an often casts are wasted since the length and angle of a cast does not permit the correct drift on the flies. The vast majority of wading fisherman that I guide step into a run without planning their approach and begin casting from one position to all of the good looking trout zones they can reach. A lot of my time guiding wade anglers is spent coaching them on the correct "setup" for their presentation. This involves wading into the correct location so that the first cast to the prime trout holding spot is going to produce the ideal presentation. By predetermining the ideal casting distance and angle for a given run and then wading into the correct location, our clients begin to greatly increase their hookup rates. Here are a few examples of common water types with some basic strategies that produce ideal drifts.
Long, Deep Runs with Uniform Currents
I generally recommend making as short a cast as possible when nymph fishing. The exception is when you are fishing long runs with uniform currents. On larger rivers, trout often hold in 3-5 feet of water in large swift runs. Flies need some time to sink to these depths even with a split shot. Short casts do not allow adequate time for the flies to sink and remain in the "money zone." In these situations making long casts at a 45-degree angle upstream is ideal. I try to make a powerful cast that I can "check" just above the water so that the flies tuck below the line and free fall quickly upon entering the run. As the flies drift toward you, one or two big mends are needed to control the drift while some of the slack that is generated is retrieved. When the flies pass your location in the river you can feed some line back while mending to continue the drift. With this, approach you should be standing about 10-15 feet away from the line of drift at its closest point to you, directly across the current.
Complicated Slicks on Spring Creeks
Smooth, glassy slicks on spring creeks appear to look fairly simple with their drift lines, but upon careful inspection you will notice that the currents are actually complicated and occur with a variety of different speeds. If you make too long of a cast, the line holds across too many lanes of current and drag results on the flies. If you cast too close, the flies look great but you have spooked the trout. A medium cast of 20-30 feet is usually ideal in these cases. The best drift angles to spring creek trout is generally made with a cast at a slightly downstream angle that allows the flies to reach the trout before the leader. When fishing under these technical conditions, it is imperative to first identify the feeding lanes in the run and then slowly and carefully wade into a position across, and slightly upstream, of the trout before making the perfect cast.
Swift water with rocks and boulders dispersed throughout is ideal trout habitat. The presence of numerous rocks also breaks the current up into a variety of different lanes of varying speeds. Trout in these locations often concentrate on the seams between the fast water in the main current and the slow eddy water behind rocks. Making long casts in these conditions results in nearly instant drag on the presentation since the line is surely holding across numerous lanes and getting pulled unevenly down river. Fortunately, trout in this fast and broken water, are not easily spooked, allowing anglers to get as close as 5 feet in some cases. The ideal presentation under these conditions is to make short casts at a 45-degree angle upstream and then immediately lift the rod high to remove the fly line off of the water. This "high sticking" technique produces ideal drifts since drag is non-existent. It is critical when high sticking to constantly change your body position so that you are located about 7 to 10 feet away from the productive seams that you target.
Brian McGeehan spends several weeks casting nymphs as a Montana Fly Fishing outfitter and owner of Montana Angler Fly Fishing.