Mention the "Henry’s Fork" in any western fly shop and you’re guaranteed to attract some attention. It is one of the most well known fly fishing trout streams in the world. Located in eastern Idaho, the Henry’s Fork is any fly fisher’s paradise. Its prolific hatches, rising fish, and incredible water diversity are enough to make any angler hungry for more. Long slow-water runs, fast pocket water, and spectacular falls characterize different sections of this world class river. On any given day you can fish everything from a size 20 dry fly to a size 2 streamer with success. However, the Henry’s Fork is most famous for technical dry fly fishing to large rising fish.
The Box Canyon, best known for the salmon fly hatch in early June, fishes extremely well early in the season. The rainbows in this section are some of the strongest fish in the Henry’s Fork. Expect superb dry fly fishing when the Salmon flies and Golden Stones are moving up the canyon. Large Stimulators, Chernobyl Ants, Turk’s Tarantulas, and many other Salmon fly patterns draw violent strikes during this time. Nymph fishing, however, is probably the most productive way to fish the Box. Kaufmann’s Rubber Leg Stones, Prince nymphs, Yuk Bugs, and Bitch Creeks will work well in this section all year. Try putting a smaller bead head dropper behind these larger nymphs. Copper Johns, Prince nymphs, Hares Ears, and Pheasant tail nymphs in sizes 12-18 are my favorite. If you aren’t much of a nymph fisherman, streamers can be very effective. Try a Kiwi Muddler or a Krystal Bugger; big fish are always looking for sculpins and leeches.
The water levels can vary from year to year, so it doesn’t hurt to have a sinking line or shooting head.
The section below Box Canyon is Last Chance. This area has some excellent dry fly fishing. The Last Chance section is the stretch of the river visible from the highway as you pass through the tiny town of Island Park. It’s a great area for sight fishing to large rainbows. The water in this section moves very slowly and is littered with aquatic vegetation which provides tremendous habitat for numerous insects. Water depths throughout this section are very consistent, making wade fishing very effective. In the early season there are prolific hatches of Blue Wing Olives followed by blankets of PMD’s. Have plenty of no-hackles, thorax duns, cripple patterns, and spinners in the appropriate colors and sizes to match these insects. Caddis hatch in unbelievable numbers throughout most of the season. Calm summer evenings allow the caddis to return to the water to drop their eggs. The late evening fishing is something you don’t want to miss. There is another larger mayfly that will show up in early June known as the Rithrogena. It will typically last up till the middle of June.
June brings the opening of Harriman State Park, the most famous section of the Henry’s Fork. This part of the river, also known as the Railroad Ranch, has some of the finest dry fly fishing in the world. The fish here can be very selective, but the opportunity to cast to trophy rainbow trout with dry flies draws anglers from all over the world. The water is shallow and meanders slowly for nine miles through the park. As a result the fish get a very good look at every bug, real or artificial, that floats down the river. Fly fishermen who frequent the Ranch have devised some of the most creative and highly productive spring creek flies in the world to fool these selective trout. In addition to having very realistic patterns, the Ranch angler must possess stealth and patience. This area of the Henry’s Fork is most effectively fished by searching for and stalking rising fish.
The match-the-hatch style of fly fishing typical of the Ranch is not for everyone. In the words of the infamous Mike Lawson, "the ranch rainbows have destroyed the egos of some of the world’s finest anglers on more than one occasion". The hatch here can blanket the river from bank to bank. In fact the hatches are often so heavy that the most productive time to target fish may be before or after the bugs have made their appearance. Dropping a tiny artificial fly into a sea of thousands of real bugs can be a painful experience. Not only is there only a slim chance of the fish eating your artificial, but an angler many times has great difficulty locating his fly amidst a thick film of naturals.
PMD's and caddis are the most consistent hatches during the first few months after the Ranch opens. Some of the best PMD patterns include the Thorax PMD, Sparkle Dun, and Comparadun patterns in sizes 16-18. Larger fish on the Ranch may key in on a specific stage in the life-cycle of these insects. Emergers and cripples are a necessity when targeting them.
My favorite caddis imitations include the Spent Partridge Caddis, CDC Elk Hair Caddis, Hemingway Caddis, and Peacock Caddis in 14-16. Caddis emergers and caddis pupa fished just below the surface are an excellent way to take fish before the hatch.
The most famous hatch on the Ranch is the Green Drake, which can last as long as two weeks. The bugs begin to emerge sometime during June, and can be found in large numbers on cool overcast days. This hatch can lure some of the largest trout in the river up to the surface to feed. We recommend a good selection of patterns for the Green Drake hatch. Emergers, cripples, spinners and duns in sizes 10-12 would be the most effective.
The Ephemerella flavilinea, commonly known as the "flav" produces superb summer dry fly fishing as well. Often confused with its larger cousin the Green Drake, the flav may be on the water with a number of other insects. This can be a great time to be on the Ranch if you can discover which kind of bug your fish is eating.. The flav hatch starts in mid to late June and can last through July. Smaller Green Drake patterns in size 14 will be great choices when the flavs are on the water.
As August approaches Trico’s and Callibaetis will begin to appear. Tricos are very tiny mayflies who often hatch in such large numbers that trout gorge themselves. Have plenty of trico spinners and arrive early in the morning to witness an impressive spinner fall. Thorax tricos, Parachute tricos, and small cripple patterns in sizes 20 -22 can be fished behind a larger caddis or Callibaetis pattern throughout the day to allow better visibility on the water. Callibaetis mayflies are found in lakes and very slow moving streams. They are easily identified by the dark pattern of spots on the wings of the duns and the spinners. Thorax duns, Sparkle duns, and parachutes in a size 14 are my favorite Callibaetis imitations.
As fall arrives so do the Blue Wing Olives and the Mahogany duns. Many of the fish have seen a number of anglers by this point in the season. Be prepared to fish longer leaders and approach rising fish with a bit more stealth. Sparkle dun patterns and no-hackles in size 16-18 are good selections for the Mahogany hatch. Thorax duns and quill body duns in 18-22s will take the fish focusing on the Blue Wings. As always it is good to have emerger patterns for the really tough fish.
As the Henry’s Fork leaves the Ranch it begins to drop in elevation. The river plunges down into a canyon which is accessible in only a few places along the Mesa Falls road. Boulders, cliffs, falls and long stretches of pocket water mark nearly the entire 15 miles of river down to the town of Ashton. The Salmonfly and Golden Stone hatches here are exceptional. During the hatch the rainbows look like overstuffed footballs, their stomachs bulging with huge insects. I like to fish the pocket water in the summer with large rubber leg dry flies. Turck’s Tarantulas, Stimulators, Chernobyl Ants, and large hopper patterns will draw fish up from the bottom. Try dropping a small nymph off the these high floating dries. Nymph fisherman can do exceptionally well in this stretch. There is a tremendous population of stoneflies in this section, and big rubber leg nymphs bounced along the bottom will draw a savage response all year long.
The Henry’s Fork offers unique fly fishing opportunities for every angler regardless of age or skill. No matter what time of year you choose to visit you can expect to find world class fishing.