Lake Powell isn't exactly a famous fly fishing destination...yet. If the proper techniques and flies are used, fly fishing can be very effective. Fly fishing success is determined by the ability to get the fly into the depth where the fish are feeding. Depending on the time of year and water temperature, the fly line and fly choices must match the depth of the active fish. Another obvious factor is the species that you are targeting.
Fly rods from 6 to 9 weight, depending on the depth and fly size. Line type will vary from floating to super fast sink either sink-tip or full sink. My choice for floating lines is either bass bug or salt water tapers. Both of these are built to throw large, wind resistant flies a fair distance. Sometimes an intermediate sink line is needed to get down just a few feet below the surface. This works when the stripers are chasing shad on or close to the surface. Smaller stripers can be targeted with intermediate lines; they often use the upper portion of the water column in the warm months. Full sink and sink-tip lines work best when stripers are in their familiar mode of suspending in large schools 25 to 70 feet deep.
Smallmouth and Largemouth Bass
Rod weight from 4 to 8, again depending on depth and fly size. I usually choose a fast action 6 weight for smallies. I have a fast 30 foot sink tip and floating lines ready to go. I often target prominent points and lines of flooded brush with surface flies on the floating line. I will often use weedless flies and an 8 weight to target largemouth in between the flooded trees. The extra stiffness of the 8 weight alows me to horse the fish clear of the linbs and land it. I will use the sink tip lines when the top water action is not happening. Fly choice is usually some kind of shad or minnow immitation.