The Big Thompson River is one of the more popular small rivers on the northern Colorado Front Range...and it is a very healthy fishery thanks to the catch and release regulations and decent flows for the last half decade!
The Big T (as it is commonly called) is a 40 minute drive north of Boulder. The river begins in the Forest Canyon area in the Rocky Mountain National Park, flows down through Moraine Park and the town of Estes Park, then into Lake Estes. The headwaters have greenback cutthroat and the Moraine meadows have everything...cutthroat, brookies, browns and rainbow trout. And the lake in town is full of dumb stocker rainbows.
Below the dam on Lake Estes is the "tailwater" section of the river, although it fishes more like a very bug rich, freestone than your stereotypical tailwater. This has more to do with the river structure than anything else. It can be swift at times, but can be some of the most enjoyable pocket water fly fishing in the area! The river follows Route 34 down through the town of Drake, then on to the mouth of the canyon and into the town of Loveland. Well, actually, the road follows the river....sorry.
My favorite section of the canyon has always been the 10 mile stretch between the Estes dam and the small town of Drake. There are rainbows and browns in this area...averaging 10 to 14 inches. There are plenty of 16 to 20 inch fish around, though! In the canyon stretch there are mainly rainbow trout (70%) with just enough browns to keep it interesting (30%).
The stream flows through the canyon can vary dramatically...and this can obviously affect the fishing. In the spring (during runoff) it is very important to check the canyon flows before taking the time to drive up for the day. You can use the stream reports on our Rocky Mountain Anglers website or go directly to the USGS site.
I have always found that the Big Thompson canyon fishes best when the flows are between 80 cfs and 180 cfs. This time of year you want to have blue-winged olive mayfly patterns with you...both dry and subsurface.