South Fork Snake River

The South Fork Snake is the Palisades Dam tailwater — 66 miles from the Wyoming-Idaho line down to its confluence with the Henry's Fork near Menan. It's the West's premier native cutthroat fishery, with Yellowstone and Snake River fine-spotted cutthroat as the primary species, wild browns concentrated in the lower river, and rainbows as the third species in the upper tailwater. Fish densities in the upper twelve miles below Palisades exceed 5,000 trout per mile, and average size runs 15-17 inches with plenty of fish over 20. The river splits naturally into three distinct stretches — the heavily-accessed upper tailwater below Palisades, the wilderness-feeling canyon from Swan Valley down to Heise (no road access for a 15-mile remote stretch), and the wider lower river from Heise on down to the Henry's Fork confluence.

The South Fork fishes well from May through October. It's primarily a float fishery, though wade access is excellent at every put-in and takeout. Drift boats are the standard rig. Flows are dam-controlled and run cold and clear all summer (typically 4,000-15,000 CFS at Heise depending on irrigation demand and reservoir level). The salmon fly hatch typically comes off late May into mid-June and progresses upstream at 5-10 river miles per day — chasing it is the classic South Fork trip. Golden stones, PMDs, Yellow Sallies, and caddis layer in through summer, with mahogany duns and BWOs taking over in fall. The mutant stonefly — a stubby-winged late-summer black stone that hatches at dawn — produces some of the most aggressive dry fly fishing on the river in late August and early September. October caddis run September-October. Hopper fishing through August on the lower river is as good as anywhere in Idaho.

The access town is Swan Valley, ID, with WorldCast Anglers (US 26) and South Fork Lodge as the primary fishing-focused operations. Idaho Falls and Rigby serve the lower river. Drive times: 1 hour from Idaho Falls, 1 hour from Jackson, 2.5 hours from Bozeman, 4 hours from Salt Lake City. The river is managed cooperatively by the BLM (which owns most of the canyon section), the Bureau of Reclamation (which operates Palisades Dam), and Idaho Fish and Game. There is no special-regulation section — statewide trout rules apply, with a 2-trout daily limit (one of which can be a cutthroat between 16-22 inches in some seasons; check current IDFG regs). The river runs murky for several weeks in May/June when Palisades discharges sediment-laden water during reservoir draw-down. Check the BLM South Fork conditions page if you're planning a spring trip.