Information About Small-Stream Fly Fishing on the Blue River in Colorado by Pat Dorsey

If you think the Blue is a place where you used to be able to catch feisty 14- to 16-inch rainbows and browns during summer PMD and Green Drake hatches, or where you used to be able to catch 5-pound and bigger tailwater trout on midges and Mysis shrimp in the winter, think again.Whirling disease and six years of drought may have put the Blue River on many anglers’ “Injured Reserve” list but, after three major habitat improvement projects and rainbow trout stocking by the Colorado Division of Wildlife, the Blue River is rapidly recovering its status as one of Colorado’s premier trout streams.

Small-Stream Fishing

The Blue begins its picturesque journey high atop the snow-capped Continental Divide, flows north off the backside of Hoosier Pass, and carves its way down to the mountain town of Breckenridge. Locals call this tightly confined, mostly private stretch the upper Blue. Below Breckenridge, the river widens and there are ample opportunities (Breckenridge Access, Gold Hill Access, and Swan Mountain Access) to sample this wild brown trout fishery before it spills into Dillon Reservoir. The Colorado Division of Wildlife (CDOW) also stocks this section with small rainbows, which adds to the thrill and excitement of small-stream fishing.

Several stream improvement projects have been completed in this area in recent years to combat the loss of trout habitat due to heavy mining and other land-use problems in the area. The rehabilitated areas have strategically placed boulder gardens, banks stabilized with riprap, and deep man-made pools for trout to over-winter. These project areas hold and attract many trout. One section in particular—an area referred to as the “steps” (Breckenridge Access)—is a long series of wing-dams that create plunge pool after plunge pool. This stretch is loaded with trout in the 8- to 14-inch range and is especially good for novice fly fishers.

Tailwater Trout

Below Dillon Reservoir, the Blue River is a classic tailwater fishery, supporting a mixed bag of rainbows, Snake River cutts, and browns. The trout fatten quickly on a diet of midges, mayflies, caddis, and thin, glasslike crustaceans known as Mysis shrimp.

Mysis shrimp were introduced to Dillon Reservoir, as well as nearby Taylor Park and Ruedi reservoirs, to feed resident Kokanee salmon. At certain times of the year these shrimp flush through the dam outlet into the rivers below, causing gluttony and rapid growth in the trout immediately below the outflow. Most of the trout in the Blue below Dillon Reservoir are between 14 and 16 inches, but trout that key on Mysis commonly reach 5 to 10 pounds.

Located approximately 60 miles west of Denver, this is a favorite stretch for anglers who enjoy the challenge of technical fishing. Cold, clear water from the bottom of Dillon Reservoir and sporadic hatches of small insects add to the complexity and difficulty of this fabled trout stream. The Blue gives up its fish stubbornly, but those who fish it regularly and master short-line nymphing techniques with 5X and 6X tippets have many rewarding days.

The section below the dam is open to angling all year and typically remains ice-free during the coldest winter months for nearly four miles below Dillon Dam. This section of river flows through the town of Silverthorne and is especially popular when other rivers become jammed with ice. A chain of factory outlet stores parallels the stream, and fast-food restaurants, gas stations, and convenience stores are nearby. The state’s major east-west interstate highway (I-70) crosses the river right above a good run—creating an urban experience in a gold medal trout stream. This may be the only place in the state where you can catch a 5-pound trout in February and buy a hot cappuccino without moving your vehicle.

Below Silverthorne

Flowing north from Silverthorne, the stream becomes a classic mountain trout stream sweeping through stands of conifers, aspen, and cottonwood trees and meadows sprinkled with wildflowers and sagebrush. The boulder-strewn river parallels Colorado Highway 9 between Silverthorne and Green Mountain Reservoir and is accessible from Blue River Campground, Sutton Unit, Eagle’s Nest, Palmer Gulch, and the Blue River State Wildlife Unit.

These public accesses are situated near beautiful trout habitat with deep runs, gravel bars, swirling pockets, and deep, clear pools. Browns, rainbows, and cuttbows in this area range from 9 to 15 inches but anglers occasionally catch fish in the 16- to 20-inch range, as well as the odd brook trout that drops down from the feeder creeks.

Kokanee salmon add to the experience later in the year as they run upstream out of Green Mountain Reservoir during the last two weeks of September and continue moving upriver for four to six weeks. The salmon average between 17 and 19 inches and are easiest to catch while they are holding in the deeper runs and pools. They eat egg patterns, Pink San Juan Worms, bead heads, and other brightly colored dead-drifted flies and sometimes chase and crush bright pink streamers.

My favorite rig this time of year is a #16 Nuclear Egg with a #20 Sparkle Wing RS II tied to the eye of the egg hook because it fools trout feeding on two important food sources. When the salmon begin to spawn, resident trout feed heavily on the eggs, and trout from the reservoir move upriver as well to partake in the feast. In this Poor Man’s Alaska it’s possible to find trout taking eggs behind the spawning redds of the salmon and then fish dry flies during the Baetis hatch all afternoon. I have experienced some of my best days during October when the river is loaded with an influx of trout from the reservoir, eggs are rolling along the stream bottom, and Baetis are hatching.

Private Water

The Blue River below Green Mountain Reservoir is known to hold monster trout. The Denver Post ran a photo of guide Matthew Burkett with a 25-pound rainbow he caught on private water the summer of 2005 (the fish was 33 inches long with a girth of 25 inches), but most anglers don’t get shots at these trout unless they are invited by a landowner or book a trip at Elktrout Lodge (970-724-3343).

Public access is limited to four small access points, but this may soon change as landowners and the Bureau of Land Management (BLM) are currently negotiating to consolidate the holdings into larger parcels. The four access points at the time of this writing are Green Mountain Canyon Access (a three-mile stretch right below the dam), a 1/4-mile BLM property above the gravel pit, another 1/4-mile BLM property above Trough Road, and finally the Yust Ranch property (two miles of public water) just above the confluence of the Colorado River. Please respect private property, and obey all no-trespassing signs. It is your responsibility to know the rules that govern these pieces of land.

Hatch Strategy

The Blue River is a typical tailwater fishery supporting a diverse number of aquatic insects. Closer to the dam, anglers can expect mostly midges, mayflies, and Mysis shrimp (depending on the flows), and the farther you progress downriver the better and more reliable the hatches are. Scores of rising fish eat Blue-winged Olives, caddis, Pale Morning Duns, Green Drakes, Red Quills, Tricos, and midges. Fishing with terrestrials brings trout to the surface through the summer months. Effective flies include hoppers (#6-10), beetles (#10-16), and ants (#14-18).

Midges hatch all year, but during the late fall, winter, and early spring they are the most reliable and important food source for Blue River trout. Most successful anglers fish a two-fly nymph rig and imitate the various stages of the midge hatch. If the fish are holding deep and no hatch is evident, your bottom fly should be a larva imitation like Barr’s Pure Midge Larva (#22). If you see fish suspended in the water column or a midge hatch in progress, use two pupa imitations. Proven patterns on this river include #18-24 Black Beauties, Mercury Midges, Rojo Midges, Jujubee Midges, and South Platte Brassies. During warm spells or in the event of an especially heavy hatch, trout rise to midge adults and can be fooled with imposters such as #22-24 Griffith Gnats, #24 Matt’s Midges, or #26 Parachute Adams.

Blue-winged Olives hatch in April and May and between late August and mid October. Overcast afternoons provide the best dry-fly fishing. Look for rising trout in the slower runs and pools, especially in the reaches above Green Mountain Reservoir. It’s not uncommon to find a pod of a dozen fish or more feeding on these sleek, olive-bodied mayfly duns. Make short, accurate upstream casts of no more than 30 or 40 feet with 6X or 7X tippets and concentrate on making repeated accurate casts to an individual trout until it finds your fly. Parachute Adams, Mathews’ Sparkle Duns, and Cannon’s Bunny Dun (#20-24) all fool trout taking duns from the surface.

Blue-winged Olive (Baetis) nymphs become active an hour before the hatch, creating excellent nymph fishing opportunities in the shallow riffles and along the edges of gravel bars. Use a two-fly rig with small mayfly nymphs such as #20-22 Pheasant-tail Nymphs, Smith’s Baetis Nymphs, Barr Emergers, or Hare’s Ears.

Expect caddis hatches between May and September through most of the drainage, and you can always catch fish during the summer on a pupa imitation such as a #16-18 Beadhead Breadcrust, Mercury Caddis, or LaFontaine Sparkle Pupa.

For dry-fly anglers, it’s hard to beat a #16-18 Elk-hair Caddis, especially when used as the top fly in a dry/dropper setup. It’s rare to find a fish taking caddis with a regular surface feeding rhythm, so covering the water methodically is your best option. The telltale splashy rise lets you know trout are taking either caddis or Yellow Sallies because there is relatively little surface disturbance when trout eat other food items such as mayflies and terrestrials.

Yellow Sallies begin to hatch in June, providing excellent dry-fly fishing in fast, shallow riffles. Anglers sometimes mistake these small yellow or lime-green stoneflies for caddis, but that’s okay, since trout in swift broken water also have a hard time telling the difference. Your caddis rig of an Elk-hair Caddis and a Deep Sparkle Pupa will take trout looking for Yellow Sallies, or you can try something more specific such as a #14-16 Yellow Stimulator with a Gold-bead Pheasant-tail Nymph. The key is to concentrate your effort on the water type that holds the most stoneflies.

Pale Morning Duns (PMDs) emerge daily during July and August and are often on the water at the same time (between 1 and 3 P.M.) as Western Green Drakes. On overcast days, expect a full-blown hatch with pods of trout surface-feeding in shallow flats and deep pools where the current seams gather the most food. My favorite PMD patterns are #16-18 Cannon’s Bunny Dun, Mathews’ Sparkle Dun, and Stalcup’s CDC Biot Compara-dun. On bright days the hatches are sparse and the mayflies fly quickly from the water. On these days, nymphing with #16-18 Pheasant Tails, Barr Emergers, and Mercury Pale Morning Dun Nymphs is the best tactic. Focus on the top of the runs where riffles dump into deeper runs or pools. Fishing behind gravel bars and mid-river shelves is also a good mid-day option.

The Green Drake hatch sometimes provides the best dry-fly fishing of the season. Many Green Drake duns emerge from their nymphal shucks just under the surface of the water. Green Drake emergers such as the Quigley Cripple (#10-12) or Stalcup’s Green Drake Nymph (#10-12) suspended just below the surface will draw crushing strikes from fish looking for a big, easy meal. Drakes don’t blanket the water like a Blue-winged Olive hatch, so you’ll have to cover the water with blind casts, or stand back and watch for several minutes to identify a feeding fish. Use a traditional dun imitation such as a #10 Hen Wing Green Drake or Mathews’ Sparkle Dun as your strike indicator in a two-fly rig.

Red Quills show up in the late afternoons (starting a 4 P.M.) during August and September. While not as dramatic as the mayfly hatches of early summer, the Quills fill an important gap as the PMDs and Green Drakes begin to wind down and fall Blue-winged Olives have yet to begin. Use #16 A. K.’s Red Quill Parachute or Stalcup’s CDC Biot Compara-dun for dun imitations and a thin, sparse #16 Pheasant Tail to imitate Red Quill nymphs.

As the summer season winds down, attractor fishing with a Royal Wulff, Limeade, House and Lot, Renegade, Humpy, or Rubber-legged Stimulator can cause aggressive takes by summer-fat fish. It’s usually best to use these types of flies as strike indicators for your nymphing rig when flows get low and the fish become suspicious of standard nymphing rigs with brightly colored strike indicators.

During higher flows, aquatic worms (earthworm brown and pink), and cranefly imitations (rockworms) work well. Egg patterns also catch fish during higher flows, and they are most effective throughout the spring and fall months when the trout and Kokanee salmon are spawning.

The Blue River in Silverthorne might not be for everyone—matching the hatch behind The Dress Barn or Tommy Hilfiger is a surreal experience—but the varied water up- and downstream of town offers a fine sampling of what the Colorado Rockies are famous for. And with all the conservation efforts going on there, it’s only getting better.

(Article reprinted with permission of Fly Fisherman)