SAN JUAN RIVER BELOW NAVAJO DAM
Sixty miles south of Durango lies New Mexico's most well-known fishery on the San Juan River below Navajo Dam. The San Juan heads in the mountains of the same name, flowing south to be impounded in Navajo Lake. Outflow from the dam is from the bottom ofthe lake, a situation that puts a constant flow of cold water into the river below, creating a marvelous tailwater fishery. If you are looking for solitude, the San Juan is not for you. But if you are looking for the chance for easy access to large rainbows, the San Juan is hard to beat. From Durango, the Navajo Dam is reached via US 550 south. From the south end of Durango, take US 160/550 south. In 5 miles, bear right onto US 550 south, heading toward Aztec. Continue 35 miles, crossing the New Mexico border, to Aztec, then turn left onto New Mexico 173. In 20 miles, again turn left onto NM 511. Access to the stream is easy from this intersection to the dam about 5 miles ahead. Outflow from the dam keeps water temperatures nearly constant at 42 degrees Fahrenheit.
The fishery is carefully managed for rainbow trout. Rainbows are stocked as fingerlings, growing up as near-wild fish and which grow to over 22 inches. Snake River cutthroats were once stocked in the San Juan, and cutbow hybrids are occasionally caught. Brown trout are unusual but may be found in the lower reaches of the Quality Water. Cold water temperatures require that anglers wear neoprene chest waders at all times. Prolific algae growth makes for slippery footing throughout the river. Additional dangers are found in the irregular stream bottom that hides deep holes and long eroded slots. Felt-soled wading shoes are essential equipment for fishing here, and chest waders should always be used with a wading belt to prevent water from flowing into your waders in case of a fall. The size of the water dictates the use of rods at least 9 feet long, especially for mending line on long floats on quiet water. Most fishing involves small flies and 4 to 6 weight lines are best. Nine-foot leaders and heavy tippet can be used fishing San Juan Worms and leech imitations, but many situations on the river call for 12-foot, 5X to 7X leaders. Angling the San Juan is always a challenge. Presentations must be exact and drifts must be drag free. But you'll have no trouble finding fish--they are everywhere. Adapt your fishing techniques to the location you select. The flats, the channels, the pools, and the riffles all hold plenty of trout. San Juan rainbows are careful, selective feeders. Successful anglers come to the river prepared to match the size and color of the dominant food source for that day. Fortunately, only a limited number of insect species are found on the river. Abundant midge hatches occur year-round, making midges the most important food source on the river. Fish feed on adult and immature insects, as well as mating clusters of insects. Midge larva and pupa patterns ranging from size 18 to 28 should be fished dead-drift at varying depths, including just below the surface.
Dry fly fishing with adult midge patterns can be effective, but if conditions are right, fishing midge cluster patterns may be more productive. Midge cluster flies are often simple black-thread bodies with a grizzly hackle tied parachute-style on a white post clipped short in sizes 14 or 16. When fish are freely rising to clusters, this type of pattern can make your day. Mayflies are found in riffles and on the flats below the riffles. Spring and fall hatches of Blue-winged Olives provide some excellent dry fly fishing, especially on calm, cloudy afternoons. Trout will rise to size 18 or 20 Blue-winged Olive patterns. From early July to late September, Pale Morning Dun hatches occur in early afternoon. The hatch is often better on sunny days. Fish them with size 14 or 16 pale yellow Comparaduns. If the fish are taking emergers below the surface, a variety of rusty, dark PMD emerger patterns should do well. Trout often take insects just below the surface. Come to the San Juan prepared to fish size 16 to 20 Pheasant Tail or dark Hare's Ear nymphs in the surface film. Sparsely tied RS2 and WD-40 nymphs, sizes 18 to 22, are also effective. Slight changes in coloration can make a big difference. When no insect activity is observed, prospect for trout with subsurface patterns. Red, orange, tan, and brown San Juan worms are effective year-round. Black or brown rabbit and marabou leeches in large sizes are a good choice in slow-moving water. Egg patterns are also popular on the river. You can find an incredible variety of patterns designed specifically for this river at local shop. Hot patterns come and go, so keep an open mind, experiment, try something different, and don't be reluctant to ask for suggestions at the local hangouts.
Excerpt from "Fly Fishing Southwest Colorado" available at Duranglers in Downtown Durango.