Sf Boise River At Anderson Ranch Dam
Sf Boise River · Rockies · USGS gage 13190500
Coldwater (summer mean 9.7°C — prime coldwater).
Water
51°F
Flow
513 cfs
Air
51°F
Sky
0%
Pressure
29.94 in
Wind
2 mph
Predicted hatches · 2026-09-15
PredictedBlue-Winged OliveBaetis spp.0.50
Predicted by conditions; no reports yet. water 10.7°C (51°F) sits in the prime band (6-11°C); shoulder of the season; 7 days sustained ≥4°C; watch midday, especially overcast afternoons.
flies: BWO Sparkle Dun #18-22, RS2, Pheasant Tail #18
PredictedMidgeChironomidae0.44
Predicted by conditions; no reports yet. water 10.7°C (51°F) is cooling past the prime band (1-10°C); shoulder of the season; 7 days sustained ≥0°C; watch midday, especially cold months.
flies: Zebra Midge #18-22, Griffith's Gnat, Disco Midge
PREDICTED from the first-principles model only. Report-confirmed signal (fly-shop & forum reports) is the next milestone.