Henry's Fork
HENRY'S FORK
ReportOvercast conditions and right after storms offer the best dry fly fishing. Nymphing remains the best producer in Box Canyon. Rubber legs and bead head nymph patterns fished deep are worth trying. Terrestrial insect patterns, including those for flying ants, dead drifted using long fine leaders in front of banks, bring trout up everywhere during warm middays.
From Last Chance to Pinehaven, mahogany duns and BWOs are emerging. Tiny BWO (pseudos) emerge best during bright light conditions. If waters from the dam down to Last Chance become turbid, switch to using small-sized nymph patterns.
Brown trout migrating upstream are the big attraction to fishing in the river above and below Ashton Dam. Streamer patterns during low light conditions are the best ways to encounter them. When warming conditions come on, presenting terrestrial insect patterns close to vegetated banks will bring trout to the surface.
Caddis are active during evenings throughout the river. Flow at Box Canyon is about 200 cfs, below Ashton Dam is about 700 cfs, and about 800 cfs at St. Anthony.
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Mahogany Dun | #14–16 | Moderate — emerging Last Chance to Pinehaven | Midday to afternoon, especially overcast windows |
| Blue-Winged Olive (BWO / Pseudos) | #22–24 | Good — tiny pseudos emerging in bright light | Midday under bright or overcast skies |
| Flying Ants (Terrestrials) | #16 | Strong — bringing trout up everywhere near banks | Warm midday hours |
| Caddis | #18–20 | Active throughout the river | Evening |
| Stonefly / General Nymphs (Box Canyon) | #6–12 | Best subsurface producer — rubber legs and bead heads fished deep | All day |
- OVERCAST / POST-STORM: Prime window for dry fly fishing with BWOs and mahogany duns from Last Chance to Pinehaven
- WARM MIDDAY (10am–2pm): Dead drift flying ant patterns on long fine leaders tight to vegetated banks — trout are coming up everywhere
- LOW LIGHT / EVENING: Streamer fishing for migrating brown trout near Ashton Dam; caddis active throughout the river at dusk
