From a placid flowing spring creek to cascading whitewater, the Henry’s Fork is likely the most diverse trout river in the world. It’s like six rivers in one. Aside from their source, streams and rivers are defined by the land over which they flow. Giant springs flush forth from the bowels of one of the largest volcanic calderas on earth. From there it meanders quietly through open meadows until it cuts its way through a deep canyon cascading down at least 1000 feet until it begins its journey through the farm country of the upper valley toward its mother river, the Snake. Mike Lawson’s latest book, Fly Fishing Guide to the Henry’s Fork, is available online for more detailed information about the fishing, hatches, access, maps and more. Fly Fishing the Henry's Fork DVD is another tremendous resource.
Henry’s Fork is, by definition, is a true spring creek above the Island Park Reservoir. Born from giant springs that gush forth from deep within the Island Park Caldera, it winds through open grasslands and willows until it necks down and speeds through rough volcanic rock to form Coffeepot Rapids. After that it stalls at the McCrea Bridge into an estuary of the reservoir. This water is managed by the Idaho Department of Fish & Game with liberal fishing regulations and is very popular with local anglers during the summer months. Perhaps the greatest asset to the upper river is its value as a spawning stream for large trout that inhabit the reservoir. Early in the spring and again in the fall, after the tourist season, it is possible to hook some truly giant fish up from the reservoir below.
This 3 mile section of river is a tailwater that flushes from the Island Park Dam. While the water is fast and difficult to wade, there is good walk-in access from a variety of parking areas. The Box Canyon is one of the most popular sections of the river for float fishing. It is also very popular with recreational floaters, especially on the weekends. With an average of 3,000 trout per mile, the fast rocky water provides a sanctuary for trout of all sizes. This productive water is home to stoneflies, caddisflies, mayflies, midges and other aquatic insects as well as leeches, crayfish, scuds and other invertebrates. Sculpins and other forage fish are at the top of the food chain for these fast growing trout.
By Idaho law, outfitters may not have more than 3 boats in a section of the Henry’s Fork at any one time. For that reason we encourage our guests who plan to fish the Box Canyon to make requests as early as possible. Nymph fishing is dependable throughout the year. Dry fly fishing is best in June when larger stoneflies are abundant. It is possible to float through the Box Canyon in less than three hours but our guides can easily make a day of it by walking their drift boats through the most productive runs.
Harriman State Park
From the mouth of Box Canyon at Last Chance, the Henry’s Fork meanders softly through open grasslands for the next 10 miles. Seven miles of this water flows within the boundary of the Harriman State Park. Originally known as the Railroad Ranch, this 11,000 acre piece of heaven was donated by Roland and Averell Harriman to become Idaho’s first state park. Most anglers simply know it as “the Ranch.”
Anglers come from all over the world to test their fly fishing skills on some of the most selective trout on the planet. Angling literature is filled with references to this water. The defining work on this water, Fly Fishing the Harriman Ranch by John McDaniel, was published in September 2012. He also produced a very detailed map of the Ranch. The density and diversity of the aquatic insect community is incomparable to anyplace else. Tricky currents make a drag-free float next to impossible. Couple this with trout that grow immense and you have “the Ranch.”
After the Ranch, the Henry’s Fork descends through a deep canyon for the next 20 miles. Much of it is whitewater with several major waterfalls. Part of it is navigatable and provides some great pocket water fishing, especially early in the season when the Salmonflies are on. There are three major waterfalls, the largest Upper Mesa Falls, is an attraction not to be missed. Two floats are popular through the canyon section. The trip through Cardiac Canyon below Lower Mesa Falls is worth doing for the scenery alone. For this float our guides drag large catarafts down a steep trail to the river.
Another popular float is from the mouth of the canyon downstream to the Ashton Reservoir, a distance of just over seven river miles. Known as the Warm River to Ashton float, the fishing is consistent and reliable through the season. It’s a great float for novice fly fishers yet there are enough large rainbows and browns to keep the most experienced angler in the game.
Some of the most productive water on the Henry’s Fork is the tailwater stretch from the Ashton Dam to the Chester Dam. This section provides 6-1/2 miles of terrific dry fly fishing from late winter into early July. This fishing picks up again in September and continues into the winter season. The diversity and density of the aquatic insects is matched only by the Ranch water above. While rainbows are the predominant trout, anglers can expect to find browns of trophy proportions.
Lower Henry’s Fork
Fall River, a major freestone tributary of the Henry’s Fork, dilutes the tailwater at the Chester Dam. From there the river continues its journey to the confluence with the South Fork of the Snake. While most of this water is easy to wade, public access is limited. Mike Lawson has fished this water since he was a boy and he has shared his vast knowledge and experience of this lower water with the guides at Henry’s Fork Anglers. Anglers floating this section can count on catching some nice trout as well as sighting Bald Eagles, Osprey, moose and other wildlife.