Clearwater River At Spalding
Clearwater River · Rockies · USGS gage 13342500
Coldwater (summer mean 13.0°C — prime coldwater; very large river (13,300 cfs)).
Water
61°F
Flow
13,100 cfs
Air
93°F
Sky
86%
Predicted hatches · 2026-06-16
PredictedEastern Green DrakeEphemera guttulata1.00
Predicted by conditions; no reports yet. water 15.9°C (61°F) sits in the prime band (14-18°C); peak season; 3 days sustained ≥12°C; watch evening; the spinner (Coffin Fly) falls at dusk.
flies: Green Drake #8-10, Coffin Fly Spinner, Drake Emerger
PredictedSalmonflyPteronarcys californica0.90
Predicted by conditions; no reports yet. water 15.9°C (61°F) sits in the prime band (13-16°C); peak season; 3 days sustained ≥12°C (wants 4); watch late morning through evening.
flies: Rogue Foam Salmonfly #4-6, Chubby Chernobyl, Pat's Rubber Legs
PredictedGolden StoneHesperoperla / Calineuria0.87
Predicted by conditions; no reports yet. water 15.9°C (61°F) sits in the prime band (14-18°C); peak season; 2 days sustained ≥13°C (wants 3); watch afternoon and evening.
flies: Chubby Chernobyl #8-10, Yellow Stimulator, Pat's Rubber Legs
PredictedSulphurEphemerella dorothea / invaria0.87
Predicted by conditions; no reports yet. water 15.9°C (61°F) sits in the prime band (15-19°C); peak season; 2 days sustained ≥13°C (wants 3); watch evening, the last two hours of light.
flies: Sulphur Comparadun #16-18, Sulphur Spinner, Pheasant Tail
PredictedGreen DrakeDrunella spp.0.70
Predicted by conditions; no reports yet. water 15.9°C (61°F) is cooling past the prime band (11-15°C); peak season; 8 days sustained ≥10°C; watch midday, often cloudy.
flies: Green Drake Parachute #10-12, Cripple, Hares Ear #10
PredictedLight CahillStenacron / Stenonema0.54
Predicted by conditions; no reports yet. water 15.9°C (61°F) is warming toward the prime band (16-20°C); peak season; watch dusk.
flies: Light Cahill #14-16, Cream Cahill, Cahill Spinner
PredictedPale Morning DunEphemerella spp.0.50
Predicted by conditions; no reports yet. water 15.9°C (61°F) sits in the prime band (13-18°C); shoulder of the season; 3 days sustained ≥12°C; watch late morning to early afternoon.
flies: PMD Comparadun #16-18, Sparkle Dun, Pheasant Tail #16
PredictedSpotted / Summer CaddisHydropsyche spp.0.50
Predicted by conditions; no reports yet. water 15.9°C (61°F) sits in the prime band (14-19°C); shoulder of the season; 3 days sustained ≥12°C; watch evening, last hour of light.
flies: Elk Hair Caddis #14-16, Iris Caddis, X-Caddis
PredictedMarch Brown (Eastern)Maccaffertium vicarium0.50
Predicted by conditions; no reports yet. water 15.9°C (61°F) sits in the prime band (14-18°C); shoulder of the season; 3 days sustained ≥12°C; watch sporadic through the day, midday into afternoon.
flies: March Brown #10-12, Hare's Ear, Spinner
PredictedSlate Drake / IsonychiaIsonychia spp.0.38
Predicted by conditions; no reports yet. water 15.9°C (61°F) is warming toward the prime band (16-21°C); shoulder of the season; 1 day sustained ≥14°C (wants 2); 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.