Big Thompson River Report

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Big Thompson River Report

9-29-2026

Flows are slowly dropping, but the fishing still remains good. Most action has been subsurface, but with the forecast cloudy and rainy days, BWO's will be active. Observed hatches are Midges, BWO's, Caddis and terrestrials.

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For dries, use a Chubby Chernobyl, Flying Ant, Rosen Para Beetle, Hi Viz Quill Midge, No See Um Hi Viz BWO, Center Stage Caddis, Ms Tickle Cripple in BWO, Griffith's Gnat, Compara Dun BWO, AR's BWO Adult and Emerger, All Season Caddis, Superman Caddis, and a Hot Mess Midge.

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For sub-surface, use a Juju Baetis, BTS Mayfly, RS-2, Puparazi, Zebra Midge, Tailwater Sow Bug, AR's Spanish Bullet, Lil Bit, Tung Stud, Thin Mint, Juggarate Chocolate Baetis, Tung Poudre Pupa and a Hogan S&M Nymph.

Guide Rating

4/5

Weather Experienced

- Temperature: Upper 50's

- Wind Conditions: Light breeze

- Precipitation: 50% chance of showers and storms

Water Observations

- Water Temperature: Mid to upper 50's

- Flow Level: 39.10 CFS

- Water Clarity: Light stain

About Big Thompson River Fly Fishing

Starting as a mere trickle on the east side of the Continental Divide, inside Rocky Mountain National Park, the Big Thompson flows from Forest Canyon Pass near the top of Trail Ridge Road through Forest Canyon. As small drainages offer additional snowmelt, the Big Thompson picks up volume, turning into one of Colorado’s finest streams.

The Big Thompson becomes fishable at Moraine Park in Rocky Mountain National Park, about six miles downstream of its headwaters. It’s there at Moraine Park, where the river splits into numerous braids and channels, that fisherman encounter the river’s first public access. Trails leading up and down the river from that point will lead you to great flyfishing experiences.

Moraine is a wide-open area, but the Big Thompson’s banks are lined with willows. It’s typical small stream conditions, and the river is filled with, you guessed it, brook, brown, and cutthroat trout in the 6- to 12-inch range. They’ll readily take a variety of general attractor flies.