Colorado ·
Blue River Fly Fishing Report - September 20, 2026
BLUE RIVER
ReportSEP 20 — 27, 2026
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Flow
245CFS
BLUE RIVER BELOW GREEN MOUNTAIN RESERVOIR, CO
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Water Temp
—
Updated 2026-09-20
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Weather
32–63°F
Chance Rain Showers
💧
Clarity
Clear
Check post-storm
Flow is running at 245 CFS below Green Mountain Reservoir with a gauge height of 3.74 ft — wadeable, clear conditions through the Gold Medal canyon stretch that are ideal for technical sight fishing. Expect a crisp fall day topping out near 61°F with mostly sunny skies and light westerly winds.
What's Working — Hot Flies
Juju Baetis Tungsten #22
22
Olsen's Hare's Ear Blowtorch Barbless #20 - 28
20
Parachute - Blue Wing Olive #22
22
Black Zebra Midge(TBH) #20
20
Olsen's Peacock Blowtorch Barbless #22 - 24
22
Roza's World Spain Perdigon Barbless #18 - 32
20
Top Secret Baetis #16
16
Egan's Silver Bullet - Baetis #14
14
Olsen's Quilldigon - Olive - Barbless #22 - 24
22
Bionic Ant 2.0 - Black #16
16
Corn-fed Caddis (CDC) Olive #20
20
Egan's CDC Rainbow Warrior #22
22
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Midge (Chironomid) | 20-24 | Heavy | 9 AM - 3 PM |
| Blue-Winged Olive (Baetis) | 20-22 | Moderate | 11 AM - 2 PM |
| Caddis | 18-20 | Light | 4 PM - 6 PM |
| Terrestrials (Ants) | 16 | Light | 12 PM - 3 PM |
Best Time Window
- 8 AM - 10 AM: Pre-hatch nymphing in the deeper canyon runs before fish get wary — midge and BWO nymphs tight to the bottom.
- 11 AM - 2 PM: Prime BWO and midge hatch window with mostly sunny skies and temps climbing toward 61°F — watch for rising fish in the flats.
- 4 PM - 6 PM: Late-afternoon caddis and terrestrial window along grassy banks — fish are less pressured and more willing to eat a dry.
Guide's Tip
From the benchWith flows at 245 CFS and gin-clear water, stealth is everything today — stay low, wade slowly, and approach fish from downstream. Focus your nymphing in the 18-24 inch depth range along the seams where faster riffle water meets slower pools, keeping your indicator or sighter tight and your tippet long (5X or 6X fluorocarbon, 18-24 inches). During the midday BWO window between 11 AM and 2 PM, watch for subtle sipping rises in the slower flats and switch to a dry or emerger — these fish are selective, so match the size of the naturals you see on the water. After landing a fish, stay in position and rest the run for a few minutes before your next cast; in this low, clear water, a spooked fish will put the whole pod down.
Main Species
Rainbow Trout
Brown Trout
Mountain Whitefish
