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Hatch predictions for 300+ US rivers — built from live water & weather, then confirmed against real fly-shop reports.

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Bitterroot River Near Darby

Bitterroot River · Rockies · USGS gage 12344000

Coldwater (summer mean 15.2°C — prime coldwater).

Water
n/a
Flow
237 cfs
Air
34°F
Sky
100%
Pressure
29.98 in
Wind
1 mph
Predicted hatches · 2026-10-31

No bugs scoring above the noise floor right now.

PREDICTED from the first-principles model only. Report-confirmed signal (fly-shop & forum reports) is the next milestone.