Discovering the allure of fly fishing the Big Thompson River Colorado is an angler’s rite of passage, a journey into the heart of the Rockies where wild trout and stunning scenery converge. This iconic waterway offers a uniquely rewarding experience, flowing directly from the pristine wilderness of Rocky Mountain National Park and carving a path through dramatic canyons before calming in the plains. The river is home to a thriving population of diverse trout species, making every cast an exciting prospect. However, true success on these waters often hinges on understanding the rhythm of its seasonal hatches and the nuances of its currents. For any angler, from the seasoned pro to the curious beginner, knowing the best public access points is the key that unlocks the river’s full potential.
Why the Big Thompson is a Fly Fisher’s Paradise
The Big Thompson River, affectionately known as the “Big T,” is more than just a place to fish; it’s a story of resilience. After devastating floods in 2013, a massive restoration effort not only rebuilt the river’s path but also re-engineered it with prime fish habitats. This has resulted in a world-class fishery with an incredible structure of pools, riffles, runs, and pocket water that challenges and delights anglers. The river’s character changes dramatically along its course, offering a variety of experiences in a single day. You can be casting to rising brook trout in a high-meadow stream in the morning and battling a hefty brown trout in a deep canyon pool by the afternoon. The proximity to the town of Estes Park also makes it incredibly accessible, blending a wilderness feel with the convenience of nearby amenities.
Understanding the River’s Anatomy: Key Sections to Explore
To truly master the Big Thompson, you need to think of it not as one river, but as several distinct fisheries, each with its own personality and secrets. Breaking the river down into its primary sections allows you to tailor your approach, gear, and expectations for a more successful outing.
The Upper Reaches: Moraine Park in RMNP
Inside Rocky Mountain National Park, the Big Thompson meanders through Moraine Park, presenting a classic high-meadow stream experience. Here, the river is smaller, gentler, and more intimate. The primary residents are wild brook trout, greenback cutthroat, and brown trout, which are often eager to rise to a well-presented dry fly. The casting can be tight due to willows lining the banks, demanding accuracy and a stealthy approach. This section is perfect for anglers who value solitude and the sheer beauty of their surroundings as much as the fishing itself. Wading is generally easy, but the fish are spooky, so tread lightly and use the natural cover to your advantage.
A Guide to Fly Fishing the Big Thompson River Colorado’s Canyon
This is the section that defines the Big Thompson for most anglers. From the Estes Park dam downstream through the Big Thompson Canyon, the river gains speed and power. It’s a quintessential freestone river environment, characterized by large boulders, deep pools, and fast-moving riffles. This is where you’ll find the highest concentration of fish, including some of the river’s largest brown and rainbow trout. Access is readily available along Highway 34, with numerous pull-offs and designated fishing areas.
“The canyon doesn’t give up its secrets easily,” says Elias Vance, a veteran Colorado fishing guide with over 20 years on the ‘Big T.’ “You have to learn to read the water. Look for the seams behind big rocks and the slower water on the edges of fast currents. That’s where the big boys are resting and waiting for a meal.”
Below the Dam: The Tailwater Fishery
Just below the Lake Estes dam, the river takes on the characteristics of a tailwater fishery. The water temperatures are more consistent year-round, which fosters prolific insect life and allows trout to grow larger. This short stretch can be incredibly productive, especially during the winter months when much of the upper river is frozen or inaccessible. Nymphing is often the most effective technique here, but don’t be surprised to find fish rising to midges even on a cold winter day.
When is the Best Time to Cast a Line?
Timing is everything on the Big Thompson. The river’s mood and the fish’s behavior are dictated by the seasons, the water flows, and the corresponding insect hatches. Understanding this calendar is crucial for any angler planning a trip.
Spring’s Awakening: The Pre-Runoff Window
As the snow begins to melt in the high country, a window of opportunity opens up. From March to early May, before the main runoff begins, the fishing can be fantastic. This period is defined by significant hatches of Blue-Winged Olives (BWOs), small mayflies that drive the trout into a feeding frenzy on overcast days. Nymphing with Baetis patterns is a consistently effective strategy during this time.
Summer’s Prime Time: The Green Drake Spectacle
Summer is the main event on the Big Thompson. After the spring runoff subsides, usually by late June or early July, the river clears and the insect life explodes. The most anticipated event is the Green Drake hatch, a large mayfly that brings the river’s largest trout to the surface. This is prime time for dry fly fishing. Throughout the summer, you’ll also encounter hatches of Pale Morning Duns (PMDs), caddisflies, and terrestrial insects like ants and grasshoppers, providing diverse opportunities.
Autumn’s Golden Opportunity
As the leaves change color, so does the fishing. September and October are magical months on the river. The crowds thin out, and the brown trout become aggressive as they prepare to spawn, displaying their vibrant colors. They will chase streamers with abandon, creating some of the most exciting hookups of the year. Dry fly action can still be excellent with late-season BWO and caddis hatches.
Gearing Up: Essential Flies and Equipment
While you could bring a dozen fly boxes, success on the Big Thompson often comes down to having the right patterns for the season and the right gear to present them effectively. A 9-foot, 4 or 5-weight fly rod is the perfect all-around tool for this river. For leaders, a 9-foot 4X or 5X leader will cover most situations, though you may want to go down to 6X when casting tiny midges in the winter. Waders are essential for most of the year to properly navigate the river and stay comfortable.
| Fly Type | Key Patterns for the Big Thompson | When to Use |
|---|---|---|
| Dry Flies | Parachute Adams, Elk Hair Caddis, Green Drake, PMD, Griffith’s Gnat | During insect hatches, especially in summer and fall. Used for surface feeding. |
| Nymphs | Pheasant Tail, Hare’s Ear, Zebra Midge, Pat’s Rubber Legs | Year-round. Especially effective in deeper pools, runs, and during winter. |
| Streamers | Woolly Bugger (black, olive), Sculpzilla, Slump Buster | Best in fall for aggressive brown trout or in high, off-color water. |
Elias Vance adds a crucial tip on fly selection: “Don’t just match the hatch, match the size and stage. If you see bugs on the water, take a moment to really look at them. Sometimes, going one size smaller than what you see, or fishing an emerger pattern just below the surface, makes all the difference.”
Navigating the Waters: Access Points and Regulations
One of the best features of the Big Thompson is its generous public access. The majority of the river flowing through the canyon is on public land managed by the U.S. Forest Service. Look for official pull-offs and designated parking areas along Highway 34 between Loveland and Estes Park. Within Rocky Mountain National Park, a park pass is required, but access is readily available in areas like Moraine Park and along the road.
Remember, while much of the river is public, there are still private stretches. Respect all posted signs. Colorado law requires a valid fishing license for anyone 16 or older. Always check the current Colorado Parks and Wildlife regulations for specific rules regarding bag limits, and any special regulations for certain sections, such as catch-and-release only areas.
The journey of exploring and learning the nuances of this incredible river is what makes it so special. Every trip offers a new lesson, a different challenge, and the chance to connect with a truly wild Colorado landscape. Whether you are a seasoned local or a first-time visitor, the experience of fly fishing the Big Thompson River Colorado will undoubtedly leave a lasting impression, calling you back to its clear, cold waters time and time again.
Reviews
Caleb R.
★★★★★
My family and I visited Estes Park from Texas, and I snuck away for a day of fishing on the Big Thompson. Absolutely epic. The scenery in the canyon is breathtaking. I’m a relative beginner, but I managed to land a beautiful rainbow trout on a Pheasant Tail nymph just by following the advice I read online. The access points were easy to find. Can’t wait to come back!
Marianne Shaw
★★★★★
I’ve been fishing the Big T for over 30 years, and it’s fishing better now than it has in a long time. The habitat restoration post-flood has been a game-changer. The pocket water in the canyon is holding a ton of healthy fish. For anyone visiting, my advice is to move around. Don’t just stay in one spot. Each pool and run is different. Great article, captures the spirit of the river perfectly.
David Chen
★★★★☆
Had a great but challenging day on the river last October. The brown trout were active and I had a few big ones chase my streamer, but they were tricky to fool. The water is crystal clear, which means you have to be stealthy. Lost a monster right at the net! It’s a humbling river that really makes you work for it, which I respect. Four stars only because I didn’t land the big one!
Sofia Petrova
★★★★★
As someone new to fly fishing, I hired a local guide for a half-day trip on the Big Thompson, and it was the best decision I could have made. My guide, Tim, was patient and taught me how to read the water and get a proper drift. I caught my first-ever trout on a fly rod here! The river is beautiful and surprisingly not too crowded on a weekday. An unforgettable experience.
Liam O’Connell
★★★★★
Fished the section in RMNP (Moraine Park) and it was a totally different experience than the canyon. Much more delicate and technical. The brook trout were small but absolutely gorgeous. It felt like a true wilderness experience. If you value solitude and a more intimate setting, I highly recommend heading into the park. Just be prepared for some bushwhacking along the banks.
