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Fly Fishing Colorado's Backcountry


It was 40 years ago when I first wet a line in a high-mountain lake, and I was hooked forever. Fishing these lakes interested me in backpacking—often the only way to fish some of the more remote alpine lakes. I enjoyed the solitude of the backcountry and not having to compete for choice waters. I honed my dry-fly fishing skills, caught more trout in an afternoon than you could shake a rod at, and stalked some beefy trout that rivaled the big boys in our state’s finest tailwaters. Best of all, I enjoyed swapping fishing tales with close friends and sharing what I learned.

Colorado’s 2,000 high lakes are the remnants of our last glacial episode that ended about 12,000 years ago. These lakes are located primarily along the crest of the Continental Divide, in the Flat Tops of northwest Colorado and in the Sangre de Cristo Range of southern Colorado. Elevations at most lakes are between 9,000 and 12,500 feet. Ninety percent are less than 20 acres in size, and three-quarters are less than 30 feet deep, making them easily fishable with a fly rod. Most can be fished from shore for at least part of the open water season.

Although more than half of the high lakes today contain trout, few high lakes in Colorado originally contained fish. People began stocking the lakes as soon as they settled the state, and by 1900 most lakes contained an assortment of different species of trout. In the majority of these lakes, only brookies and lakers can successfully reproduce so other species must be stocked periodically to maintain populations. Today, Colorado Parks and Wildlife stocks a large number of these lakes on a regular basis and introduces predominantly inch-long cutthroat trout—greenback hybrids to the east of the Divide, Rio Grande cutthroats to the west of the Divide in the southern mountains, and Colorado River cutthroats to the west of the Divide elsewhere. Brookies persist in many lakes, often overpopulating the lakes and seldom reaching 12 inches. However, in some lower elevation lakes where populations are sparse, I’ve caught brook trout up to 20 inches. Cutthroats grow slowly in the cold mountain waters, reaching 12 inches in 3 years, 16 inches in 5 years, and topping out at over 20 inches. They can live for up to 14 years.

Anglers will be pleased to know that fishing high lakes has many similarities to fishing lower elevation streams and rivers. However, there are also many differences. Fish respond to weather, water conditions and insect life similarly in both types of water. In rivers and streams, the water is moving and the fish are primarily stationary, holding in feeding lanes. However in lakes, the water is stationary and the fish are constantly moving. Understanding the movement of trout is the key to successfully fishing high-mountain lakes. Trout in high lakes move in response to water temperature, insect hatches, light intensity and cover.

Water temperatures completely dominate the lives of cold-blooded trout and dictate where they are found in high lakes. Beneath the ice of most lakes in winter, trout can be found near the bottom where the water is the warmest. When lakes below timberline thaw from late May through June, winds effectively mix all waters so that the lake becomes an even 39 degrees Fahrenheit. With increased daylight and solar radiation, the near-shore and surface waters warm faster than the rest of the lake. Hungry trout that were trapped beneath ice for seven or eight months move into the warmer shallows to feed. This is classic ice-out fishing, and trout can be readily taken on streamers and wet flies fished parallel to shore. Search for trout along drop offs, submerged rocks, sunken logs and weed beds. Successful patterns include No. 8 or 10 black Marabou Leeches, Woolly Buggers, Muddler Minnows, orange soft hackles and Royal Coachman streamers stripped on a full-sinking line. Ice-out conditions last at a given lake for up to three weeks until temperatures climb above 55 degrees. Then, trout below timberline will move toward the middle of lakes to access cooler, deeper water and be less accessible to anglers.

Summer brings insect activity to the high lakes and the opportunity to match the hatch. The entomology at high lakes is dominated by midges. Midges are the first insects to hatch after ice-out and the last to hatch before the lakes freeze in the fall. The first midges to hatch have large black bodies with white wings and can be matched with a No. 16 or 18 Black Gnat. Then progressively smaller midges in grays and tans appear. Trout often sip midge larvae in the surface film, leaving telltale dimples that resemble raindrops falling on the water’s surface. Effective patterns in this situation include a No. 16, 18 or 20 Orange Asher or Griffith’s Gnat or a No. 20 Black Beauty, RS2 or Andy’s Flash Pupa suspended off a dry fly indicator. Often stripping a bead-head Orange Asher in the film will also take fish.

Caddisflies are perhaps the next most important insect because of their size and high activity. The pupae wiggle energetically toward the surface when water temperatures climb above 45 degrees. They are effectively imitated with a No. 14 Gold-ribbed Hare’s Ear, Lafontaine’s Emergent Sparkle Pupa or bead-head caddis stripped either below the surface or in the surface film. The Elk-hair Caddis fished dry will take trout even when there are no caddis hatching. Other important insects include Callibaetis mayflies below timberline and gray drake mayflies above timberline. No. 14 and 16 Adams and Mosquitoes are good imitations of the adult, while a Pheasant Tail imitates the nymph. In addition, terrestrials like flying ants, beetles and small grasshoppers, can be important in July and August.

Along with temperature and insect hatches, trout in high lakes move in response to light intensity and cover. Trout move into the shallows when light is low at dawn or dusk. On cloudy days, trout are often more active and move closer to shore. However on bright sunny days, trout often move into the deeper water to filter the bright light. Trout also move to shore under the temporary cover of a lake surface that is rippled by a stiff breeze. The broken surface diffracts light and makes trout less wary.

Anglers should also be aware that stocking patterns can heavily influence one’s fishing experience. While it is obvious that stocking controls the presence of different species within a lake, the frequency and numbers of fish stocked will influence catch rates. Periodic stocking every two to four years often results in healthy populations of cutthroats, providing that the lakes don’t winterkill and are not overharvested. However, stocking one-inch fry in lakes already containing a large population of brookies often provides them with a good food source and a fondness for streamers. Stocking few fish or stocking infrequently can result in a lake with a small number of large, trophy-sized cutthroats. But this is no problem because at a high lake it only takes one five-pound trout to make one’s day.