The 6 Best Fly Fishing Rivers in Colorado, in our opinion, range from the Animas down near Durango to the South Platte up by Denver.  

The Centennial State contains countless rivers with hundreds of creeks branching and emptying into them. With thousands of square miles of river, it would take an angler a lifetime to explore all of them. While fishing every waterway in Colorado would be a life well-lived, we have taken into account what we consider some of the best fly fishing rivers in Colorado. As always, this is merely our opinion and open to discussion.

Animas River

The Animas River is a world-class river system with a pedigree of large fish. Spanning one hundred feet or more wide in some areas, the Animas provides plenty of space and adequate food sources for the brown and rainbow trout to grow to a significant size. The former Colorado state record brown trout of 20 pounds was hauled from the Animas in the 1950s. Both private and public opportunities are available on the Animas. The town of Durango offers almost seven miles of riverbank to access fishing.

Rio Grande

The second-longest river in the United States, the Rio Grande is a gold standard for Colorado fly fishing. Here, you’ll find a variety of fish with brown trout making up a large percentage. The Rio is both wadeable and floatable depending on the season with its long runs and deep pockets. While there’s a good bit of public access, you can find that those close to the road get a fair amount of pressure. On the other hand, private waters are nearly unfished as many of the properties are working cattle ranches whose owners don’t have time to wet a line. If you’re lucky, you might also pull a few cutties out of the Rio as well as cutbows. 

San Juan River

The San Juan River is home to healthy brown and rainbow trout populations. Public access for the river is pretty sparse in many areas with the exception of in and around Pagosa Springs. 

The other area that the San Juan River is most famous for is the Navajo Dam. This tailwater is in New Mexico, so it’s important to ensure proper licenses are in hand before fishing it. The best fishing on the river is with access to the stretches of private river between the upper and lower San Juan. Rolling hills and ranch land make this riverway very good for brown trout and rainbows that lurk in the deep pools.

Piedra River

In southwest Colorado, the Piedra River creates some of the most jaw-dropping scenery available. With deep pools shadowed by carved cliffs to open meadow streams, the Piedra will leave an impression long after you have left. 

Rainbow and brown trout are the most common fish in the river, but cutthroat trout are also found throughout the river system. The canyon system is accessible by hike-in only. Since this requires leg work, you may be fishing these pools by yourself. For a location unlike any other, this is the river system to try. 

A word of caution though, with the canyons’ high walls, it’s not advised to try and fish the early spring runoff where the snowmelt comes rushing through the canyon. Wait for runoff to end before fishing through the box canyon.

Dolores River

The Dolores River is two different fisheries in one river. The tailwater fishery between Rico and the Dolores reservoir features a healthy brook, brown, and rainbow trout population. Much of this area reservoir is accessible publicly. The lower river is primarily private land with larger fish receiving less fishing pressure. Fish gorge themselves on the hatches of salmon flies, caddis, and midges, all common hatches on the Dolores.

South Platte River

The South Platte is hardly an unknown river, but it deserves mentioning for several reasons. The South Platte is near Denver, allowing traveling fly fishermen fast access after leaving the airport. Rainbow, cutthroat, and brown trout can all be caught in the Platte. 

The most iconic section of the river is located on the north fork above the Eleven Mile Reservoir and below the Spinney Reservoir, known as the Dream Stream. This section of tailwater and meandering river is available for public access. While this may increase the number of fishing “neighbors,” the quantity of large fish that cruise this stretch of river more than makes up for it.

While many of Colorado’s rivers and creeks may hold a monster brown or have a hatch that will live on in campfire tales for decades, the evidence points to a handful of river systems that are the best. Rivers that are healthy enough to support sustainable numbers of trout. Rivers that feature a blend of public and private access, with enough room to fish alone if need be. Those are the characteristics that make up an excellent fly fishing river.