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Big Thompson River

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.

River description excerpted from Flyfisher's Guide to Colorado by Marty Bartholomew
River description excerpted from Flyfisher’s Guide to Colorado by Marty Bartholomew

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Latest Guide Report

Fishing Report Date: 03-05-2018

The Big Thompson is fishing well. Canyon closures begin about 3 miles into the canyon, single lane traffic from mile marker 67-68.

Midges begin to come off around 10 and ramp up from noon to 2 or so. If you want to catch fish on small dries give these patterns a stab. Griffith’s gnat (#22), stuck in the shuck midge (#22), or an Adams (#22) Dry dropper rigs have been working pretty well since flows have been ranging from 17-22 cfs. Proven nymphs have been black or olive zebra midges (#20-22). A black zebra with a red bead has been pretty productive lately. Other nymphs include blue poison tungs (#20-22), sparkle midge (#22), and red and black two-bit hookers (#20). Watch out for the wind this time of year.
Report Statistics
3.5/5Time on Water:
Number of Anglers:
Hoook Ups:
Fish Landed:
Weather Experienced

Wind Conditions: Calm
Precipitation: None
Water Observations

Water Temperature:
Flow Level: CFS
Runoff? Clear

Report Submitted By: Randy Hanner

Big Thompson River Water Flow Graphs