First, I know the exact level of the water column where trout are feeding and holding in fast water – within about one foot of the river bottom. Due to friction with the river bottom, water currents move much slower along the bottom than they do at the surface. Trout stay directly on the bottom in fast water to conserve energy, and too much energy is generally required for trout to rise to the surface to feed on prey. Since trout are mainly feeding at the bottom, I also know the majority of their food is being taken in the form of nymphs. I use a bounce nymphing rig to attach my nymphs 10 inches and 18 inches off the bottom so my flies basically drift directly into a fish’s mouth.

Second, trout generally are less picky and easier to catch in fast water. I’ve watched trout in slow pools follow my flies 10 yards downstream before rejecting them, but in fast water, trout have only a split
second to decide if they want to eat your flies or not. Because fish must quickly decide if your fly presentations are real or not, you can often get away with fishing bigger and less exact nymph patterns compared to the actual aquatic insects which are currently hatching in the river.

Third, the trout you catch in fast water tend to be bigger in size. Big trout can fight fast currents easier than small trout, and baitfish are also easier for big trout to nab in fast water as they get sucked
downstream. Since trout only have a split second to decide if they want your fly or not, it’s also a lot easier to fool a big, educated trout in fast water than in slow water.

Fourth, I can get away with using a heavier leader and tippet. I regularly fish the West Branch Delaware River which receives a lot of angling pressure, and very light line is often needed to catch trout in slow water. When I use light line, I lose a lot of big fish during a fight, and lose a lot of flies from snags. Since trout can’t overanalyze your presentation in fast water, I get away with using heavier 3X and 4X tippets. This means I lose a lot less fish and am more likely to get my rig back during a snag up.

Last, trout can congregate by the masses in fast water during an aquatic insect hatch and when water temperatures heat up in the summer months. Fast riffles support an abundance of aquatic insects, and trout will move into fast, shallow water during an abundant hatch to feed on prey easier. Warm
water holds less dissolved oxygen, so in the warm summer months when water temperatures heat up, trout will often move into the faster, more oxygenated water.

More nymphing tips in fast water and all water types can be found in my guide book SIMPLE NYMPHING FOR TROUT IN RIVERS & STREAMS.

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