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Fly Fishing The Big Thompson River – Colorado

The Big Thompson River is an awesome trout fishery located in Colorado. Often referred to as the “Big T”, it starts high up in Rocky Mountain National Park, and then flows down into Estes Park. After it reaches Lake Estes, the river turns into a tailwater. Below the Lake Estes dam, the river gets a bit more technical, with more fishing pressure and picky trout. After this tailwater section, it flows into the Big Thompson Canyon which offers great fishing as well. Eventually, it reaches the South Platte River.

The Big Thompson is roughly 78 miles long, and holds trout throughout its entire length. If you’re looking for a fun small stream to fish, the Big Thompson should definitely be on your list. Its proximity to the front range offers trout fishing close to home.

Big Thompson River Access

There are so many access points on the Big Thompson River. We will start up high in Rocky Mountain National Park, and then work our way down.

Moraine Park / Cub Lake Trailhead

This is on the upper reaches of the river, and Moraine Park offers wonderful fishing. This is a meadow section with undercut banks as the river winds through the valley floor. Here, you can fish dry flies, nymphs and streamers. There are some surprisingly large fish in this section, especially the larger brown trout.

Off of Bear Lake Road, you can take a quick right onto South Moraine Road. Here, there is a small parking lot. From this lot, you can work your way up the meadow section for a long ways.

If you want to start higher up, you can park at the Cub Lake Trailhead or the Fern Lake Trailhead. From these lots, you can access the upper portion of the river, which usually means less anglers. On this stretch, you will encounter more Brook Trout.

The Tailwater Section

Below Lake Estes, the Big Thompson turns into a tailwater section. Here, you must use smaller flies, lighter tippet, and be more stealthy. The access for this area is super easy – turn off of Mall Road towards the dam, and there is a larger parking lot for anglers. Here, you can easily access the tailwater for a day of fly fishing.

The tailwater section is often fished during the winter months, because it doesn’t freeze. The Moraine Park section totally freezes over in the winter, and becomes un-fishable. Winter anglers can access the tailwater with ease, and fish all winter long.

Big Thompson Canyon

Below the tailwater section, the Big Thompson follows highway 34 down into the town of Loveland. This canyon stretch offers wonderful fishing, especially during the summer months. There are many, many dirt pull offs where anglers can find some water for themselves. During the summer, the dry fly fishing can be amazing in the canyon – there are many insect hatches such as Caddis, Pale Morning Duns and Yellow Sallies.

The canyon is also a good choice if the tailwater section is too crowded. You can find some real solitude in the canyon.

Flies To Use On The Big Thompson

The Big Thompson has many insect hatches, and is actually quite prolific in terms of bug life. Coming prepared with the right flies will help you have more success on this river.

Winter Insects

In the winter, midges will be the main hatch. Having a good selection of midges in sizes #18-#24 will help you, especially on the tailwater section where there are more midge hatches. Make sure to have some midge dry flies as well for the tailwater section.

You can also fish streamers in the winter, just make sure to move them slow – and fish the deeper pools.

Spring Insects

In the spring, Blue Winged Olives start to hatch on the Big T. Having a good selection of BWO’s is always a good idea, in sizes #18-#22.

You can also fish midges in the spring as well.

Throwing streamers in the spring is also a good choice, as the Rainbow Trout are more aggressive due to the spawn.

Summer Insects

Summer on the Big T brings lots of bug life. You will find Caddis, Pale Morning Duns, Yellow Sallies, Green Drakes, Ants, Beetles and Hoppers.

The fish can get a little more picky during the summer, as they will key in on a certain hatch – so identifying the hatch and matching it is crucial. This is especially true on the tailwater section below the dam. There are often multiple hatches happening at once, which can make fishing a bit trickier.

Fall Insects

During the fall, Blue Winged Olives come back into play in sizes #18-#22. Make sure to have BWO nymphs as well as some dries.

You can also do well with streamers in the fall, as the Brown Trout start to get more aggressive due to the spawn. I like to fish smaller streamers such as Woolly Buggers and Sculpzillas.

In the fall, you will see Caddis and Hoppers on some days. Fishing a dry dropper setup can produce great results.

Best Months To Fish The Big Thompson

The tailwater section can be fished year round, since the water temperatures are very consistent. Winter is actually my favorite time to fish here, as there are way less anglers. During the warmer months, the tailwater section can get extremely crowded, which is less fun.

For the Moraine Park section and the canyon section, summer and fall are the best times to fish. During the winter and spring, these sections have lots of ice, and are un-fishable.

Trout Species Of The Big Thompson

The Big Thompson contains mostly Rainbow Trout and Brown Trout. However, on the upper reaches in Rocky Mountain National Park, you will find more Brook Trout, and even the stray Cutthroat here and there. If you are looking to get into some Brookies, fish the upper reaches.