Snake River
Chironomids are on the water just about everyday, but the real surface action is on blue-winged olives which begin to pop around 1pm and intensify around 3pm and wane about an hour later. The most active water is almost exclusively in seams along eddies and in riffle current margins. Longer, slower runs can have actions further out in main currents.
Nymphs are producing from about 11am until dusk with the sweet spot occurring after 1pm. Go with dry-dropper rigs with tippet in the three to four and a half foot range and target riffles, seams, confluences, eddy seams, and ledge rock pools. The morning hours can produce with double nymph rigs with leader in the five to six foot range from trailing fly to suspension device.
Streamers are working better with the cooler weather in and taking a good number of fish on the mid-reaches from Moose down the South Park. Use moderately sized imitations fished on floating lines and sinking tips in the INT to 3ips range. Slow to moderate retrieves with steady line strips in key. Target banks, structure, troughs, and the inside turn of riffles (the latter later in the afternoon.
Dry flies – Mary Kays, Parachute Extended Body BWOs and Mahogany Duns, Copper Hazes, Parachute Adams, Comparaduns, Booty’s BWO Emerger, Booty’s DL BWO Cripple, Parachute Midges, CDC Midge Emergers, and Film Critics.
Nymphs – Peach Fuzz Jigs, Duracells, Copper Johns in red, copper, or black, Lightening Bugs, Egan’s Iron Lotus, Perdigons, Booty’s Day-2 Midge Pupa, and Zebra Midges.
Streamers – McKnight’s Home Invader, Craven’s Swim Coach, Yellow Buggers, Booty Call Minnows, and Arum’s Lil’ Kim.
South Fork
Blue-winged olives are the name of the game when it comes to surface action on the South Fork most days. The feeding has been best in slow, glassy water types in riffle pools, backwater side channels, and along banks with slow current and moderate depths.
Nymphing is productive from around 10am until late afternoon with the best action occurring in riffles, riffle pools, and seams. As on the Snake, dry-droppers (double droppers are worth considering when fishing dries) working just as well as on double/triple nymph rigs. Go with dropper tippets in the three to six foot range. Roe imitations are the one pattern getting into fish consistently in riffles with shallow depths and moderate current speeds. Flats are worth targeting with egg patterns as well.
Streamers are still working well on the South Fork but a bit of an upside down bell curve most days with the morning and late after new hours being the hot time and the mid-day stretches being more inconsistent. The lower reaches from Wolf Eddy down to Lorenzo are still fishing best with baitfish imitations, although the upper reach is doing pretty solid. Go with moderately sized streamers and fish them on floating lines or intermediate sinking lines. Slow retrieves are the default presentations. Going moderate with paused line strips every now and then is a good fallback.
Dry flies – Parachute Extended Body BWOs and Mahogany Duns, Parachute Adams, Snowshoe Duns, Booty’s DL BWO Cripple, Parachute Midges, CDC Midge Emergers, Chez’s Krystal Wing Midge Emerger, and Pheasant Tail Emergers.
Nymphs – Pat’s Rubber Leg, Brush Hogs, Duracells, Psycho Princes, Flashback Pheasant Tails, Military Mayflies, Perdigons, Zebra Midges, Otter’s Soft Milking Eggs, Veiled Eggs, and Clown Egg Clusters.
Streamers – Strolis’ Masked Avenger, Goldilocks, Rustic Trombones, Arum’s Lil’ Kim, Booty’s Tri-Bunny, Baby Bunnies, and Kreelux.