Beaverhead River At Twin Bridges
Beaverhead River · Rockies · USGS gage 06023100
Trout (marginal) (summer mean 19.1°C — trout, warm in summer).
Water
73°F
Flow
179 cfs
Air
72°F
Sky
51%
Pressure
29.87 in
Wind
2 mph
Predicted hatches · 2026-07-31
PredictedHexagenia (Hex)Hexagenia limbata0.55
Predicted by conditions; no reports yet. water 22.7°C (73°F) sits in the prime band (19-23°C); shoulder of the season; 8 days sustained ≥18°C; bright moon — night activity; watch after dark — the famous night hatch.
flies: Hex Dun #4-8, Hex Nymph, Hex Spinner
PredictedHopper / TerrestrialsAcrididae (grasshoppers)0.50
Predicted by conditions; no reports yet. water 22.7°C (73°F) sits in the prime band (17-24°C); shoulder of the season; 8 days sustained ≥14°C; watch warm, breezy afternoons.
flies: Morrish Hopper #8-12, Chubby Chernobyl, Dave's Hopper
PredictedSlate Drake / IsonychiaIsonychia spp.0.43
Predicted by conditions; no reports yet. water 22.7°C (73°F) is cooling past the prime band (16-21°C); peak season; 8 days sustained ≥14°C; watch afternoon/evening; nymphs crawl to shore to emerge.
flies: Isonychia #10-12, Slate Drake, Leadwing Coachman
PredictedTricoTricorythodes spp.0.22
water 22.7°C (73°F) is cooling past the prime band (16-21°C); shoulder of the season; 8 days sustained ≥15°C; watch early morning spinner falls.
flies: Trico Spinner #20-24, CDC Trico, Griffith's Gnat
PREDICTED from the first-principles model only. Report-confirmed signal (fly-shop & forum reports) is the next milestone.