Colorado River At Lees Ferry
Colorado River · Southwest · USGS gage 09380000
Coldwater (summer mean 11.8°C — prime coldwater; very large river (10,500 cfs)).
Water
70°F
Flow
9,320 cfs
Air
81°F
Sky
0%
Pressure
29.74 in
Wind
6 mph
Predicted hatches · 2026-09-15
PredictedSlate Drake / IsonychiaIsonychia spp.0.93
Predicted by conditions; no reports yet. water 21.2°C (70°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
PredictedHopper / TerrestrialsAcrididae (grasshoppers)0.56
Predicted by conditions; no reports yet. water 21.2°C (70°F) sits in the prime band (17-24°C); shoulder of the season; 8 days sustained ≥14°C; warm sun favors it; watch warm, breezy afternoons.
flies: Morrish Hopper #8-12, Chubby Chernobyl, Dave's Hopper
PredictedTricoTricorythodes spp.0.47
Predicted by conditions; no reports yet. water 21.2°C (70°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.