October 18, 2023
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The morning frost helps you appreciate that extra cup of coffee because you know there’s no reason to rush to the river. The crisp air carries little humidity, the mountains seem closer, the rivers are clearer, and the shorter daylight hours seem to sharpen your attention. Like you, the trout are also more focused. Gone are the all-night feeding sessions, and the trout instead flip-flop to a diurnal feeding behavior, necessitated by water temperatures and seasonal hatches.
Memorial Day to Labor Day is tourist season in the Rockies, when family vacations are in full bloom, the riverside parking lots are full, and the summer heat causes oppressive midday doldrums. But when the aspen hillsides turn golden, and the first frosts in the valley hit the rivers, the fishing becomes magical.
The changing of seasons brings solitude, consistent flows, dependable hatches, opportunistic trout, and spectacular landscapes filled with magnificent colors. With the days getting shorter, and the end of the season in sight, the fair-weather fishermen have put their rods away, while serious anglers feel a gravitational pull toward the river.
Autumn has opportunities for all fly fishers. Passionate dry-fly anglers can capitalize on some of the best surface activity of the year. Tailwater junkies find some of the finest sight nymphing of the season, especially for spawn-run brown trout. And it would be an understatement to say the streamer fishing isn’t bad, either.
Fall is arguably the best dry-fly fishing of the season; at the very least, it is the most dependable. Precipitation-fed freestone streams are at the lowest flows of the year, providing anglers with consistent dry-fly opportunities.
Bottom-release tailwaters provide similar conditions, as the need for downstream agricultural water becomes less demanding in the fall. Autumn hatches are impressive, with scores of rising fish feasting on midges, Tricos, and Blue-winged Olives as they prepare for the long, harsh winter that lies ahead.
Dense midge hatches occur each morning between 8 and 10 A.M., then again in the late afternoon. As the season progresses toward winter, the midge hatches will center themselves around the warmest hours of the day.
Fly fishers should familiarize themselves with all stages of the midge life cycle because matching the hatch often involves imitating a specific stage of midge development. Make sure your fly boxes are stocked with plenty of red and pale olive larvae in sizes 18-20, pupae in 20-22, and adults in 20-24. Some of my favorites include Mercury Blood Midges, Medallion Midge Pupae, Top Secret Midges, Griffith’s Gnats, and tiny Parachute Adams.
Tricos produce a feeding frenzy that is unequaled by any other mayfly emergence of the year. Tricos are often dubbed the “white-winged curse” because they bring out the best (or worst) of any serious dry-fly angler.
In late summer female Trico duns begin hatching in early morning, and mating swarms develop later. The spinner fall follows shortly thereafter, usually lasting for an hour or two. Male Tricos hatch the evening before the spinner fall, and while you can fool a few trout with dun imitations just before dark, your main emphasis should be placed on the morning spinner fall.
Spent-wing Tricos have a distinct silhouette that distinguishes their appearance from the duns. Spinners lie flat on the water, with the tail, abdomen, and wings outstretched. Fly fishers who fail to switch from upright dun imitations to spentwing patterns will most likely become frustrated from their inability to catch fish.
Unlike duns that leave the water quickly, dying spinners remain on the water for long periods of time. Trout recognize this opportunity and feed on them with a sophisticated singularity. My favorite Trico imitation is Shane Stalcup’s CDC Trico Compara-dun. It fishes well for both Trico duns and spinners, and can be fished as a drowned spinner by simply adding a small split-shot.
By late September, the Trico hatch takes on a new twist as the males no longer hatch in the evening due to cooler air temperatures. Cool mornings have the same effect on the females too, which delays the hatch an hour or two, and that fall “magic” happens when you no longer have to wake up early for good fishing.
The two hatches (the males, which normally hatch in the evening and the females that hatch in the morning) evolve into one event, with the male duns hatching first, followed by the females. Spinner falls typically occur around noon and last for an hour or so.
Blue-winged Olives also provide fall fly fishers with consistent dry-fly fishing almost every afternoon, and on overcast days it can become absolutely epic. On rainy days or the first snowfall of the year, don’t stay home. The most dependable Blue-winged Olive hatches occur in nasty weather, as inclement conditions delay the emerging process and keep the duns sitting on the water longer. If Mother Nature is kind enough to drizzle or snow all day, expect a blanket hatch where you can see thousands of duns on the water at one time. Hatches may start earlier and last longer under these conditions.
My favorite Blue-winged Olive patterns include #20-24 Mathews’s Sparkle Dun, Barr’s Vis-A-Dun, Cannon’s Snowshoe Dun, and Hi-Vis Baetis.
Bright, sunny conditions accelerate the development of adult mayflies, helping the duns leave the water quickly. Don’t let bluebird days fool you however—fishing can still be excellent with Baetis nymphs. It’s hard to go wrong with Stalcup’s Baetis Nymph, Craven’s Juju Baetis, or a standard Pheasant-Tail Nymph (#18-20) when the trout are aggressively feeding on the small, dark mayfly nymphs. These tiny nymphs are lightly weighted, so you’ll need an assortment of split-shot, or Perizzolo’s Nymphing Mud (formerly called Mojo Mud) to get your flies to the right depth.
At the end of your dead drift, allow the flies to swing upward under tension as the dark, rising nymphs imitate the swimming action of the naturals. Likewise, swinging soft-hackles with conventional wet-fly tactics is another reliable tactic any time Blue-winged Olives have been hatching. Charlie Craven’s Soft Hackle Emerger is one of my favorite emerger patterns.
Autumn is the best time of the year to catch truly large brown trout.
By late September, wary brown trout begin moving from deeper water and other heavily structured areas into shallow water searching for areas to spawn. Large brown trout also migrate from stillwater impoundments, or warmer downriver areas, and move upriver into spawning areas with the same goal in mind.
Brown trout become vulnerable during the fall because their spawning behaviors override their normal instincts to hide beneath overhead structure, and to feed during the low-light hours. Brown trout that have been off the grid for several months suddenly appear on the radar for two or three weeks.
Take advantage of this opportunity, because your window is short and sweet. Brown trout take on magnificent colors as they prepare to spawn. Their olive-brown backs fade into a rich golden-yellow flank, sprinkled with brown and red dots outlined with a brilliant silver-blue halo. Males get pumpkin-colored bellies and develop pronounced hooked jaws called kypes. During the spawning season, brown trout become territorial, and are often willing to eat or chase anything that comes nearby.
COLORADO RIVER. The Middle Park section of the Colorado River has several easy access points and plenty of public water. The most popular destinations include Paul Gilbert, Lone Buck, and Breeze State Wildlife Areas (SWAs) near Parshall.
These areas have beautiful riffles, runs, and deep pools. They provide fly fishers convenient walk-and-wade access with opportunities to catch fish on nymphs, drys, and streamers. Expect to catch brown trout between 10 and 16 inches, with a few trout surpassing 18 inches. Last fall, my fishing buddy Mark Plowden caught a 21-inch brown in the Breeze SWA.
The Pumphouse-to-Radium section offers the option to either float or walk/wade the Colorado. If you fish from an inflatable raft or drift boat you'll experience one of Colorado's best drifts through a beautiful landscape known as Mini Gore Canyon. Inexperienced oarsmen should be aware of the Eye of the Needle, a technical stretch that requires above-average rowing skills.
If you prefer to walk, focus on the Pumphouse Recreational Area between the mouth of the canyon and the campground, which equates to about a mile of stream. There are several braided sections with shelves and gravel bars that cater to nymph fishers. You'll catch mostly brown trout and whitefish in this section, with the occasional rainbow. Walk/wade access is also available by parking in the Radium Recreational Area parking lot and walking upstream.
WILLIAMS FORK. The Williams Fork is a beautiful tailwater with 2 miles of public access between Williams Fork Reservoir and the confluence of the Colorado River. It has a mixture of riffles, runs, pools, and superb pocketwater, all loaded with brown trout from 10 to 16 inches.
During the autumn, migratory fish from the Colorado River enter the Williams Fork to spawn, and the average size of the fish becomes noticeably larger. Fish between 14 and 18 inches are common in late fall, and browns over 20 inches are caught in this section every year. They are impressive giants for such a small body of water. If the flows are above 250 cubic feet per second (cfs), the fishing becomes challenging. Ideal flows are between 100 and 200 cfs.
You can have good dry-fly fishing in the fall, but nymphs and streamers are the most effective when trying to fool the larger brown trout from the Colorado. It can be hard to focus on the subsurface activity, as excellent hatches of midges, Tricos, and Blue-winged Olives bring many smaller trout to the surface.
CHARLIE MEYERS SWA. The meandering meadow stretch of the South Platte between Spinney and Elevenmile Reservoirs used to be locally called the "Dream Stream" but it's now officially named after the late outdoor writer Charlie Meyers, who was a great conservationist and frequent fly fisher on the South Platte.
In late September to the third week of October, migratory trout move from Elevenmile Reservoir into the South Platte searching for areas to spawn. Brown trout up to 28 inches are caught every season here, making it one of Colorado's best trophy trout waters. Spotting and stalking your target is the best way to fool a large brown trout, as during the low fall flows, the trout are extremely spooky.
The biggest fish sit in the deep runs and holes, seeking refuge from the hordes of anglers trying to catch them. Most of the spawning occurs at night or during the lowlight hours when the fish feel comfortable enough to enter shallow water. I recommend getting to the river early and staying late to increase your odds.
If you sit in a hole and blind cast, you'll have very little success here this time of year. Savvy fly fishers walk several miles each day scouting the water. Look before you cast is the way to go. New fish enter the system hourly, so it's to your advantage to fish as much water as possible.
Please refrain from fishing to trout actively spawning or positioned on the redds. Disturbing spawning trout is unethical, and will have adverse effects on yearly recruitment of wild fish. The goal here is to catch the trout during their migration, and before they actually begin spawning.
ARKANSAS RIVER. The stretch of river near Salida is a dry-fly paradise in its purest form. The cottonwood-lined Arkansas flows through a lush valley with the Collegiate Peaks providing a stunning backdrop. This has always been one of my favorite destinations when I'm seeking a little solitude. It's not that few fly fishers visit the Arkansas, it's just that there's so much room for them to spread out.
The fish here are small on average (10 to 14 inches) but there are lots of them, and they feed opportunistically at the surface on midges, Blue-winged Olives, and various attractor patterns. There is also a growing population of whirling disease-resistant Hofer rainbows in the Salida area, with many of them in the 14- to 16-inch range. My favorite stretches are the Stone Bridge Recreational Area, Smyth Lease, and Big Bend Lease.
Flies & Tactics
Don’t go fishing in the fall without a full selection of egg patterns. Several species of gamefish (brook, brown, Kokanee salmon, mountain whitefish, and in some areas even rainbow trout) propagate during the fall. Because they don’t all spawn at exactly the same time, eggs can be an important food source for nearly two months.
Observant fly fishers know that every gamefish deposits a slightly different-colored egg. I tie a variety of McFly Foam egg patterns in different sizes and in different colors to cover my bases. The most productive colors for me are apricot, McCheese, golden, and chartreuse.
Kamloops rainbows, which frequently spawn during the fall, drop a chartreuse-colored egg, so you’ll need to adjust accordingly. Even if there aren’t Kamloops rainbows around, a chartreuse egg is a great attractor pattern in the Rockies from October through April.
Whitefish spawn between October and November and imitations of their eggs can be deadly when the whities broadcast their eggs on gravel bars and shallow riffles. Whitefish eggs are cream-colored, and smaller than trout eggs, requiring another adjustment.
Most egg imitations are too big. I tie my egg patterns on #18 scud hooks and keep them about 3/16" in diameter. I also tie micro eggs on #20-22 scud hooks, which can be important when trying to imitate whitefish eggs.
Egg patterns are best in riffled water below spawning flats and tailouts. Egg/midge and egg/Baetis combos are excellent tandem rigs from October until the first part of December.
While eggs and small nymphs catch most of the fish during the fall, streamers catch more of the really big brown trout. I use large articulated streamers, Meat Whistles, Slumpbusters, Autumn Splendors, Woolhead Sculpins, and Conehead Woolly Buggers.
Streamer tactics vary greatly from one angler to another depending on the conditions and what they want to accomplish. The most common method is the strip-and-swing technique—cast your streamer across-stream, allowing the fly to swing in the current and then add extra action by stripping line in quick 3- to 6-inch pulls. Vary your retrieve and never rule out experimentation. Sometimes a slow strip triggers a strike while other times a faster retrieve creates explosive strikes when a trout thinks its prey is escaping. Generally, the colder the water, the slower you’ll need to move the fly, so that fast retrieve you used successfully in early October might not be the best approach by Thanksgiving.
There are two schools of thought when fishing streamers. You can fish blind and cover all the water methodically, or you can cast your flies to specific holding areas, allowing them to swing into the desired structure or in front of sighted fish. You can also slow the fly by adding slack into the line, or mending, and you can speed it up by tightening the line, and forcing the fly to swing and rise in the current.
To work the fly deeper, try using sinking-tip lines, either integrated sinking-tip lines or looped-on sinking tips. You can also add a split-shot to the leader 12 to 18 inches ahead of the fly. Trout don’t even seem to mind it if the split-shot slides right down to the fly, and some guys start fishing with the split-shot snug on the eye of the hook.
The size of the split-shot and the distance from the hook affect both the depth of the fly and the action. There is no right way or wrong way here, just be able to make modifications based on the depth and speed of the water, and the mood of the fish.
A good rule of thumb is to move a streamer quickly in slow water, and move it slowly in fast water.
Dead-drifting a streamer is extremely effective at times, especially in faster riffles, point bars, and mid-channel shelves (everywhere you’d normally think would be a good spot for nymphing).
Fish sitting in transitional areas love to crush a streamer when they see it drift over a drop-off, and while stripping a streamer in fast water tends to compact a fly, allowing it to dead-drift lets the hackles, rubber legs, and other fibers breathe and come to life in the water.
A high-stick approach works best for dead-drifting streamers because you can control the depth with the butt end of your leader, simply moving your arm up and down to achieve the proper depth. When a trout takes your streamer the line will tighten abruptly. There will be no doubt you’ve had a strike. Once you feel the line go taut use a strip set or lift the rod tip to set the hook.
Pine Squirrel Leeches or Mayer’s Mini Leeches are both excellent dead-drift streamer patterns. I use them in a tandem nymphing rig, using the leech as the attractor, and adding one or two smaller nymphs below it. It’s surprising how many fish smash the streamer, even when small midges and BWOs are the dominant food sources.
Whether you like to fish streamers, nymphs, or drys (or all three) late autumn is a special season. Pack an extra jacket, a Thermos of hot coffee, and enjoy “off season” in the Rockies.
Stalcup’s CDC Trico Compara-dun
- Hook: #20-24 Tiemco 100.
- Thread: Black 8/0 UNI-Thread.
- Tail: White Microfibetts.
- Wing: White CDC.
- Body: Black goose biot.
- Thorax: Black Superfine.
- Hook: #18-24 Tiemco 101
- Thread: Light Cahill 8/0 UNI-Thread
- Tail: Medium dun hackle fibers, one shank length long
- Wing: Cerise McFlylon
- Hackle: Medium dun, tied parachute style
- Body: BWO Superfine
- Hook: #6-10 Tiemco 5263
- Conehead: Brass
- Thread: Brown 6/0 UNI-Thread
- Tail: Brown Marabou with copper Krystal Flash
- Underbody: Lead wire (.030")
- Body: Brown chenille
- Rib: Copper Ultra Wire (small)
- Legs: Yellow rubber legs (medium)
Pat Dorsey is co-owner of the Blue Quill Angler in Evergreen, Colorado. He is the author of Tying & Fishing Tailwater Flies: 500 Step-by-Step Photos for 24 Proven Patterns (Stackpole Books, Headwater Books, 2010).