S Twin River near Round Mountain
S Twin River · Sierra / West · USGS gage 10249300
Coldwater (summer mean 13.7°C — prime coldwater).
Water
58°F
Flow
2 cfs
Air
82°F
Sky
0%
Pressure
29.67 in
Wind
12 mph
Predicted hatches · 2026-07-31
PredictedPale Morning DunEphemerella spp.1.00
Predicted by conditions; no reports yet. water 14.7°C (58°F) sits in the prime band (13-18°C); peak season; 8 days sustained ≥12°C; low pressure — fish looking up; watch late morning to early afternoon.
flies: PMD Comparadun #16-18, Sparkle Dun, Pheasant Tail #16
PredictedGolden StoneHesperoperla / Calineuria1.00
Predicted by conditions; no reports yet. water 14.7°C (58°F) sits in the prime band (14-18°C); peak season; 8 days sustained ≥13°C; low pressure — fish looking up; watch afternoon and evening.
flies: Chubby Chernobyl #8-10, Yellow Stimulator, Pat's Rubber Legs
PredictedSpotted / Summer CaddisHydropsyche spp.1.00
Predicted by conditions; no reports yet. water 14.7°C (58°F) sits in the prime band (14-19°C); peak season; 8 days sustained ≥12°C; low pressure — fish looking up; watch evening, last hour of light.
flies: Elk Hair Caddis #14-16, Iris Caddis, X-Caddis
PredictedSalmonflyPteronarcys californica0.55
Predicted by conditions; no reports yet. water 14.7°C (58°F) sits in the prime band (13-16°C); shoulder of the season; 8 days sustained ≥12°C; low pressure — fish looking up; watch late morning through evening.
flies: Rogue Foam Salmonfly #4-6, Chubby Chernobyl, Pat's Rubber Legs
PredictedGreen DrakeDrunella spp.0.55
Predicted by conditions; no reports yet. water 14.7°C (58°F) sits in the prime band (11-15°C); shoulder of the season; 8 days sustained ≥10°C; low pressure — fish looking up; watch midday, often cloudy.
flies: Green Drake Parachute #10-12, Cripple, Hares Ear #10
PredictedSulphurEphemerella dorothea / invaria0.47
Predicted by conditions; no reports yet. water 14.7°C (58°F) is warming toward the prime band (15-19°C); shoulder of the season; 8 days sustained ≥13°C; low pressure — fish looking up; watch evening, the last two hours of light.
flies: Sulphur Comparadun #16-18, Sulphur Spinner, Pheasant Tail
PredictedSlate Drake / IsonychiaIsonychia spp.0.23
water 14.7°C (58°F) is warming toward the prime band (16-21°C); peak season; low pressure — fish looking up; watch afternoon/evening; nymphs crawl to shore to emerge.
flies: Isonychia #10-12, Slate Drake, Leadwing Coachman
PREDICTED from the first-principles model only. Report-confirmed signal (fly-shop & forum reports) is the next milestone.