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The South Fork of the Snake River

The South Fork of the Snake River is in southeastern Idaho close to the Wyoming border. The South Fork begins as it flows out of 20 mile long Palisades Reservoir in the community of Swan Valley, forming a 64-mile stretch of legendary tail-water fly-fishing. The South Fork is also a beautiful river for flat water rafting, canoeing and kayaking. If you float this river in a canoe know what you are doing as it is big water and its flat-water appearance can fool you to its dangers.

Bald eagles and Ospreys are prevalent and many nest high above on treetops along the riverbanks, it is always a treat to see one swoop down and catch an unsuspecting fish. The South Fork Snake River has been called Idaho’s most unique riparian ecosystem containing the largest continuous cottonwood ecosystem in the state. The South Fork provides habitat for nine nesting bald eagle pairs and up to 100 wintering eagles. The U.S. Fish and Wildlife Service considers this river section to be the most important fish and wildlife habitat in the state of Idaho. Moose are seen regularly in the river bottom.

The South Fork of the Snake boasts 4,000 fish per mile, which makes it one of the most productive rivers in the country. The quality of fishing on the South Fork has improved dramatically since a slot limit was introduced. All fish between 8 and 16 inches (the prime breeders) must be released and you are only allowed to keep two fish that aren’t rainbows. The South Fork also is an all-wild trout fishery as they quit planting it years ago. It is said that it is the best wild-trout fishery in the lower 48 states. Wild native cutthroat trout are a mixture of both fine-spotted and Yellowstone races. Fine-spotted cutthroat are stocked as sub-catchables and catchables into Palisades Reservoir and some are flushed into the South Fork with reservoir drawdowns.

Although exotic wild rainbow, hybrid, and brown trout provide a significant component of the catch throughout the South Fork drainage, they pose a potential threat to the genetic integrity and long-term viability of wild cutthroat populations. Stocking in the mainstem and tributaries was discontinued in the early 1980s.

The majority of anglers practice the catch-and-release ethic, because of this and the slot limit the river has maintained a healthy population of breeding fish. The river is primarily a cutthroat fishery; however, it is also possible to get into a fair number of browns and rainbows. In recent years we have seen a dramatic increase of the rainbow population and the Idaho Game and Fish is encouraging fisherman to kill all rainbow caught. As much as I prefer to catch a brown or rainbow because of their better fighting ability I would also like to maintain a healthy Cutthroat population because they are more likely to be caught on a dry fly than Rainbows and Browns.

The key to fishing the banks of this river while floating is getting your fly as tight to the bank as possible and allowing it to drift just inches form the bank in most spots. When fishing from a gravel bar its possible to hook and land a dozen or more. This is one reason why the South Fork has gained a reputation as one of the country’s greatest trout fisheries.

After spring runoff and the start of potato irrigation there is very limited access for wade fishing due to high river flows so a float trip is recommended from June till September. A drift boat allows access to many of the productive gravel bars and side channels that are inaccessible on foot. There are also many miles of the South Fork inaccessible from roads.

The first 12 miles (section one) begins at the Palisades Dam and ends at the Connant boat ramp. This is the most accessible and as a result, the most crowded. Despite the crowds, some of the larger fish tend to be caught and released on this upper section of the river. This section of river provides outstanding views of the rugged mountains on either side of the river and hosts one of the most picturesque small waterfalls anywhere. The downside is some are calling this section “the parade of homes” for the growing number of trophy homes springing up along it’s banks.

The 24-mile stretch below Connant boat ramp is considered the “Canyon,” the Canyon is divided into two sections called the middle and lower (or section two and section three). Section two ends at Cottonwood Boat Ramp. There are many National Forest campgrounds along the riverbanks. Camping is a great way to enjoy the river and break up the long canyon section. Both section one and two make for exceptional one-day fishing trips. The canyon is spectacular, with walls towering hundreds of feet straight up from the river and dotted with pine trees. The canyon gives the impression of a wilderness trip although you are floating right below cultivated barley and wheat fields you can’t see. It is common for an experienced angler to boat 30 fish a day with the average fish ranging from 16 to 18 inches.

Access to section three is through Ririe ID; you drive up a dirt road on the north side of the river to Cottonwood boat ramp and start you float there. There are several places to fish along the road if you don’t have a boat.

Section four starts at Byington Boat Ramp in Ririe and goes to where it joins up with the Henry’s Fork of the Snake by Manan ID. The river here changes character as it is no longer in the mountains, it is flatter, more braided and winds through private farmland but is an awesome fishery none the less, many big browns can be found here. Most boaters take out at the Lorenzo river access off of highway 20 between Idaho falls and Rexburg ID but the lightly fished section below Lorenzo can be very productive and there is a takeout right below where the South Fork merges with the Henry’s Fork.  For the best dry fly action the river is best fished from July through mid August. The first half of July is the height of the prolific stone fly hatches, which brings just about all of the fish to the surface to gorge themselves on one of the largest dry flies, the largest of the Stone Flies the Salmon Fly is sometimes 3 inches in length.

By the first week of August the fish are a bit more reluctant to bite as most have been caught and released several times by then. When the fish continue to refuse dry flies, emerger and cripple patterns are highly effective, especially “when the fish are feeding in the riffles and back channels.

The warm summer days of August bring out one of the trouts favorite foods, the grasshopper. When the fish are keying in on hoppers and are becoming weary of hopper patterns, try twitching a rubber legged hopper pattern. The twitching motion of those rubber legs can entice a wary fish into a strike.

Educated trout can sometimes be fooled with a dropper fly. A dropper is a nymph, emerger or attached to a buoyant and visible fly attached with an 18 inches of 4X or 5X tippet to bend of the hook. Hoppers, Turck’s Tarantula and the Double Humpys are excellent flies to set up with a dropper. The large high floating dry works well to spot the takes on the small drys, nymphs and emergers.

October brings in a season of extremes, the fishing can be the best but the weather can be the worst. For those willing to take the gamble and come in October the rewards can be tremendous. The cooler weather of fall bring on the Blue Wing Olive hatches and many of the fishermen have left for the year and gone hunting and the trout lose their weariness of flies that they acquire during the heavy fishing pressure of summer. These hatches last well into the winter. This time of year the browns are moving to their spawning beds and there are increased chances of catching big browns. The Idaho State record brown was set at 26.6 pounds and was taken on the South Fork. Monster browns in the 15-pound class are taken every year.

Fall is also a better time of the year for the wade fisherman as the lower water flows of fall open up many places to wade that are inaccessible during higher water.


South Fork Rods and Reels:
All-Purpose Rod:  Diesel 590-4 All-Purpose Trout
Streamer Rod:  Diesel 690-4 Streamer Rod
Trout Spey:  Diesel 5110-4 Trout Spey/Switch
Single Hand Fly Reel:  Diesel 5/6 Fly Reel
Trout Spey Fly Reel:  Diesel 7/8 Fly Reel
Leaders/Tippet:  0-5x

– Various All-Purpose Nymph patterns
– BH Pheasant Tails
– Midges
– BH Hare’s Ears

– Buggers
– Leeches
– Zonkers
– Small Intruder style flies

Dry Flies:
– Elk Hair Caddis
– Parachute Adams
– Wulffs
– Humpies
– Hoppers