Henry's Fork
HENRY'S FORK
ReportDry-dropper rigs, large nymph and terrestrial insect patterns fished close to banks remain standard for Box Canyon fishing success. Overcast conditions, which have been frequent recently, offer the best fishing with early AMs best. Tricos are most active early with tiny BWOs taking over until the sun gets too bright. Terrestrial insect patterns, including those for spruce moths, dead drifted in front of banks bring trout up everywhere.
From Warm River downstream, summer heat makes early and late in the day the best time to fish. PMDs are becoming much less numerous as summer rolls on, but tiny BWO activity is beginning, a few mahoganies are showing, and late in the day caddis activity brings fish up. Weed growth can be dense in slower waters. Take a break during bright middays and maybe until evening as the river is warmest in the afternoon. Try a streamer pattern of choice during low-light conditions.
Flow at Box Canyon is about 680 cfs, below Ashton Dam is about 1400 cfs, and about 1220 cfs at St. Anthony.
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Trico | #20–22 | Spinner fall, early morning | First light to 9 AM |
| Blue-Winged Olive (BWO) | #20–22 | Emerging adults, best under overcast | Mid-morning until sun brightens |
| Spruce Moth | #12–14 | Terrestrial fall along banks | Morning through early afternoon |
| PMD | #18–20 | Declining — sporadic adults and emergers | Morning (below Ashton) |
| Mahogany Dun | #16–18 | Just beginning, scattered | Midday to afternoon (below Ashton) |
| Caddis | #18–20 | Evening egg-laying and adult activity | Late afternoon into dusk (below Ashton) |
- FIRST LIGHT TO 9 AM: Fish Trico spinner falls and early BWO activity in Box Canyon and throughout the upper river — overcast mornings are the best of the best.
- LATE AFTERNOON TO DUSK: Below Ashton Dam and at St. Anthony, caddis activity picks up and streamer fishing in low light can be excellent — avoid the warm midday hours.
- ALL DAY (OVERCAST ONLY): When clouds move in and stay, dry-dropper rigs with terrestrials and large nymphs tight to Box Canyon banks can produce throughout the day.
