The South Fork of the Snake River
Midges. As in most other tailwater rivers, midges are the most abundant aquatic insect. They emerge throughout the year, but are most prolific during the cold winter months. Most of the larger mayflies and caddis hatches are over by mid-October and the trout really begin to key in on the smaller insects. The slicks, quiet pools, and tailouts are the best spots to find midge-feeding trout. They usually pod up as they softly sip the tiny flies. The trick is to try to pick off the trout feeding at the edge of the pod. If you hook a trout in the middle of the group, you’ll risk putting down the entire pod of fish.
Like caddisflies, the midge’s pupal stage is usually the most important for the angler. For that reason, I like to tie on a high-riding pattern such as a Griffith’s Gnat, and tie a midge pupa as a dropper about a foot off the hook bend. That way if I see the top fly move or hesitate, or if I see a rise or boil near the dry, I can set the hook. I like to tie my midge pupa patterns very lean, with a thread or biot body and a touch of dubbing or soft hackle at the hook eye. The best colors are gray, dark olive, or rusty brown.
Seasons
Idaho is one of the few states that still has a fishing season. It opens the Saturday before Memorial Day and closes November 30. The section from the measuring cable below Heise to the confluence with the Henry’s Fork is open year-round.
Spring. Spring runoff normally starts in May and can continue until mid-July. When the snowpack is light, the river can clear as early as the third week in June. Because the river is very difficult to fish with a fly rod and can be downright treacherous during runoff, I would take advantage of the other great fly-fishing opportunities nearby, including the Henry’s Fork, Blackfoot, and Firehole Rivers.
Once the runoff starts to subside, you can start catching trout on streamers and rubber-leg patterns by casting up against the banks. Swinging a streamer through the deep runs with a fast-sinking line is the best way to slam one of the giant browns that inhabit the South Fork.
Summer. The hatches get into full swing as soon as the runoff subsides in July. The South Fork gets a lot of local traffic, and I try to avoid it on weekends because of its proximity to Idaho Falls and Jackson Hole. The best thing about the summer, however, is that there is always something hatching, no matter what the weather or conditions are like.
The flows drop as the demand for irrigation decreases. In July it is often hard to find much access unless you have a boat, but by mid-August you can fish lots of spots from the road. By September you can wade many of the shallow runs and access most of the side channels. You can get stream-flow information at http://www.idaho.usgs.gov/rt-cgi/gen_tbl_pg/ or by calling (800) 658-5771. The fly shops also keep up-to-date on the latest stream-flow information.
Fall. If I had only two weeks to fish the South Fork, I would wait until late October. I’m amazed at how little interest there is in the South Fork during the autumn months. I have never experienced better fishing, with dries, nymphs, or streamers, than on the South Fork during October and November. By then the normal flows are low enough to enable wading anglers to access every part of the river. Pods of trout rise throughout the day on hatching Blue-winged Olives and midges.
Knowing this is the best time of the year to catch a trophy-size brown can leave you in a real dilemma. I usually take two rods, one rigged for dries and the other for streamers. I like a 4-weight rod rigged with at least a 12-foot leader for my late-season dry-fly fishing. For the streamer rod I like an 8-weight with a 6-foot fast-sinking tip to get the fly down quick when I’m fishing the undercut banks. I use a short leader, not more than four feet, so the fly will stay down. If I’m fishing deeper runs, I’ll slide a cone head down the leader to the fly in order to keep it deep. Rubber-leg Woolly Buggers, sculpin, and Muddler-type patterns are usually effective.
Winter. Midges offer outstanding dry-fly fishing during the winter. I’ve had great fishing on days when I had to break the ice out of the guides on every other cast. The stream flows are low enough to provide wading access almost everywhere. The best part is that you normally never see another angler. I also like to keep my streamer rod handy. Many anglers hold the misconception that brown trout are the major predators in the river, but I’ve also caught some huge cutthroats on streamers at this time.
The Critical Flows
As is the case with so many other great rivers, we cannot take the outstanding fishing on the South Fork for granted. Current politics in Idaho favor using the river as a means to move irrigation water to the potato fields of the Snake River Plain. Flow management is the responsibility of the Bureau of Reclamation, whose past decisions have resulted in dangerously low winter flows while filling Palisades Reservoir, and unnecessarily high floods in the spring after miscalculations of the amount of storage in the reservoir.
Studies conducted on the South Fork by the Idaho Department of Fish and Game indicate that flows lower than 1,500 cfs are lethal to fish and other aquatic life, but as this is written, the river’s flow is just over 1,000 cfs. The local chapter of Trout Unlimited, the Snake River Cutthroats, has made a great effort to protect the river, but they could use your support (www.snakerivercutthroats.com). The Idaho State Council Trout Unlimited (www.idahotu.org) and Idaho Rivers United (www.idahorivers.org) can also provide you with more information. My hope is that the great fishing that I have enjoyed on the South Fork can be preserved for generations to come.
Mike Lawson is former owner of the Henry’s Fork Angler. He has an upcoming book Fly Fishing the Henry’s Fork with Greycliff Publishing. He lives in St. Anthony, Idaho.
Accommodations
• The South Fork Lodge (877) 347-4735
• Teton Valley Lodge (800) 455-1182
• The Lodge at Palisades (208)483-2222
• Three Rivers Ranch (208) 652-3750
• Heise Cabins (208) 538-7312
• Hansen-Silver Guest Ranch (208) 483-2305
• Timberwolf Resort (208) 483-3581
• Granite Creek Guest Ranch (208) 538-7140
• Cutthroat Inn (208) 538-7963
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