Island Park Reservoir, ID

The reservoir lies north and west of Harriman State Park. It is the source of the Henry's Fork at Box Canyon, site of the Island Park Dam. Like Henry's Lake, Island Park is a relatively shallow lake and offers many fly-fishing opportunities. Unlike Henry's Lake, access to the best fly-fishing areas is good and in most cases you can drive right to where you plan to fish. Island Park is a man-made lake, fed on the north by the Henry's Fork of the Snake and on the west by many small streams and springs. It is primarily a rainbow fishery with some Brook Trout, Cutthroat and Kokanee. The quality of fishing has really been a roller coaster over the past several decades. Increased populations of rough fish, draw downs from drought, and poor bureaucratic management have contributed to the problems. The Idaho Fish & Game Department has killed all of the fish in the reservoir at least once during the past four decades in an effort to eliminate rough fish. The Island Park Reservoir is still a first rate fishery but it could be a lot better. Like most waters improving the fishery is a complicated package but the reservoir is definitely better fishing when there is enough water to keep the reservoir level from being drawn down during the winter months. The west end of the reservoir is the top fly-fishing area, reached by driving west from Harriman State Park over Green Canyon Pass, about a 10-mile drive on a good gravel road. There are long fingers and coves all along the lake with small roads out to most of the points. You can camp on some of the points and there is also a Forest Service campground available. Fly-fishing is good off most of the points and in the coves. The action starts in mid-June and continues throughout the season. Fishing leeches and Woolly Worms through the weedbeds is the most productive method. You'll need a medium or fast-sinking fly line. Sometimes the strike is very soft, but as soon as the fish is hooked, hang on! Dry-fly fishing can be excellent on Island Park Reservoir but it is often unpredictable. Morning hours are best, before the wind comes up, as the big rainbows cruise the coves and near the weedbeds, rising to numerous callibaetis mayfly duns and spinners. These fish can be a real handful on light tackle. Imagine a six-pound rainbow smashing through the weeds on a 5X tippet! The fish usually aren't selective about fly patterns. Accurate casting is much more important. A #14 or #16 Adams will take fish when they're rising.