December 14, 2022
By Pat Dorsey
The South Platte River near the tiny hamlet of Deckers is arguably one of the best trout fisheries in the United States. Its close proximity to two major cities (Denver and Colorado Springs), stunning geographic locale, easy access, wild trout, and consistent year-round fishing are what separate this world-class stream from all the others. Toss in the huge upswing in fish numbers in recent years, and you really have something to talk about. With this kind of accessibility and opportunity, this stretch of river can be quite crowded during fair weather months, but between November and March it’s a different, quieter place with far fewer people.
The South Platte's Winter Fly-Fishing Water
In the winter, choosing the right location and water type can make or break your success. It’s important to stay away from fast water and target the softer margins, where you’ll find trout stacked up like cordwood. Winter trout are stingy feeders—they overwinter in the slower runs and deep pools that provide them with the greatest amount of food while expending the least amount of energy.
An interesting phenomenon referred to as “winter warm and summer cool” by aquatic biologists is what makes winter fishing possible in many locations on the South Platte. The Deckers area is tailwater where nutrient-rich water with relatively stable water temperatures flows from the base of a man-made impoundment.
And as strange as it might sound, the warmest water in the reservoir flows from the bottom during the winter months, and the coldest water in the reservoir exits the base of the dam during the summer. In the summer that water heats up in the sun as it flows downstream. In the winter, the water cools as it flows downstream, so the best locations to fish in and around the Deckers area are closest to Cheesman Lake—between the Cable Hole (the lower boundary of the Teepee Club, which is private) and Bridge Crossing Picnic Area.
Below Bridge Crossing Picnic Area to the confluence of the North Fork of the South Platte, the fishing depends on river flows. If outflows from Cheesman Reservoir are 150 cfs (or greater) the entire river usually remains fishable to the confluence of the North Fork. If Denver Water opts to reduce the output because of a lack of downstream demand, the lower river jams up with ice and often becomes unfishable.
If you arrive on the lower river and see anchor or slush ice, drive upstream until the conditions improve. As you progress toward the dam, the water temperature gradually gets warmer and the ice disappears. Unless the outflows are below 100 cfs, the river is typically ice-free from the Cable Hole down to Trumbull.
South Platte River Hatch Strategies
There’s a common belief among South Platte regulars that if you can consistently fool trout near Deckers, chances are good that you can catch trout anywhere in the world. I wholeheartedly agree—the South Platte River has the reputation of humbling anglers on a daily basis.
Growing up in Littleton, Colorado gave me the opportunity to frequently test my skills on some of the toughest trout in the country. It didn’t take me long to figure out that if I could regularly catch fish near Deckers—especially in the winter—fishing was a little easier everywhere else.
During the winter, you need to bring your A-game and focus your attention on midge fishing. I cannot overemphasize the importance of familiarizing yourself with the life cycle of midges. Come prepared to imitate the various stages of their development, and be sure your fly boxes are crammed with an ample supply of larvae, pupae, and adults.
Some of my favorite larvae imitations include Mercury Blood Midges, Rojo Midges, pale olive larvae, red larvae, Miracle Nymphs, and Demon Midges. Midge larvae are generally larger than pupae, so they work well as attractors in a tandem nymphing rig. The larger offering helps separate your smaller flies from the crowd without going overboard. I avoid fishing with large or gaudy attractors like red or pink San Juan Worms, Mop Flies, and Squirmy Wormies during the winter because they are often red flags in these slow-moving currents and have a tendency to spook trout instead of attracting them.
I typically trail two pupae off a larva to complete my multi-fly nymphing rig. Proven patterns include: Top Secret Midges, Black Beauties, Jujubee Midges, South Platte Brassies, Periwinkles, Pearl Jams, Zebra Midges, and Manhattan Midges. When choosing your dropper flies, smaller is always better. The difference between catching a few fish and not catching fish at all may be as simple as using a size 24 or 26 fly instead of a 22.
Don’t be surprised if you see a few sporadic Blue-winged Olives in early November. If you see a smattering of midday BWOs emerging, it’s never a bad idea to use one of Charlie Craven’s Juju Baetis as your lead fly (attractor), and trail two tiny midge patterns behind it. I’d have a few Craig Mathews’s Sparkle Duns handy in a size 22 in the event you stumble upon a fish or two feeding on tiny mayfly duns. But make no mistake about it—Blue-winged Olives take a subordinate role in comparison to the midges.
The best window of opportunity is between 10 A.M. and 3 P.M., but there are several other variables that can affect the fishing as well. It’s not uncommon for air temperatures to dip well below zero in December or January, resulting in an even slower start. Clear nights without a cloud ceiling produce the coldest temperatures. Adjust your arrival times based on current weather trends. Sometimes it’s just not worth showing up until late morning.
The water temperatures typically start off in the mid to upper 30s around 9 A.M., but gradually rise through the day.
A three- to five-degree temperature swing during the day can make a huge difference in your success.
The greatest challenge of winter fishing is often finding a feeding fish. For every dozen trout you come across, only a couple of them are actually eating. It’s not difficult to catch a trout that is feeding, but it is almost impossible to catch a trout that is not. It’s important to pay close attention to any visual clues that may help you decipher whether or not a trout is actively feeding. If a trout is nailed down to the bottom of the river, it’s safe to assume that the fish is not feeding. Ignore these types of fish and try to find fish that are suspended in the water column—a sure sign they are eating.
Look for trout sweeping back and forth eating pupae. Watch for the white of a trout opening its mouth, flashes in the water, or fish changing levels. These are all good indications that these are “catchable” fish.
If there are no obvious hatches, I fish with two or three midge larvae and dredge my imposters close to the substrate, where the greatest concentrations of naturals are found. Pale olive, cream, and red larvae are great options in a tandem nymph rig.
I typically use a 9-foot tapered leader terminating in 5X, then attach 12 inches of 6X tippet with a blood or surgeon’s knot to lengthen it. On the terminating end of the leader (tippet) I tie on an attractor pattern with a clinch knot; then trail an additional 12-inch piece of 6X tippet off the bend of the hook to fasten my second fly. I repeat this process if I opt to use a third fly. In most cases, I use a third fly because it stacks the odds in my favor and allows me to dial in the hatch when trout are feeding selectively.
When a midge hatch becomes evident, I swap out my larvae imitations for pupae. Larvae look like tube-shaped segmented worms. Pupae, on the other hand, have a swollen or bulbous thorax that contains the wings and legs of the emerging adult. I choose my flies based on the appropriate size, shape, and color of the aquatic insects present. Use a seine to see what’s in the water. If I am in doubt on the size, I always err on the small side.
Once I see adult midges buzzing around, it’s a good indication that the trout are keying on pupae. At this point, it’s extremely important to adjust your weight and strike indicator to get your flies in the correct feeding zone. During peak emergence, too much weight is as problematic as not enough. Typically a number 4 or 6 split-shot is sufficient to keep your flies drifting mid-column.
I’m a huge fan of yarn strike indicators because they create delicate deliveries and register subtle takes. Bobber-type indicators hit the water hard and often spook trout. If the fish move into a transitional zone or the riffles during the height of a midge hatch, make the necessary adjustments to keep your flies at the proper depth.
If you notice trout dimpling in a glassy pool, a size 22 to 24 Parachute Adams, Z-Lon Midge, Griffith’s Gnat, or Matt’s Midge are great options for dry-fly enthusiasts who are up for a challenge. Long leaders (12 to 15 feet) and 7X tippets are often required to fool these surface feeders. A downstream cast, with a reach mend, stacks the odds in your favor because the fly precedes the tippet.
Browns on the Rise
I’ve guided the South Platte River near Deckers for the past three decades, so I feel like I have a pretty good grasp on the trout populations and overall health of the stream. Over the past three years my catch rates on guide trips and personal days on the river indicate there is a substantial uptick in brown trout populations. I recently reached out to Colorado Parks & Wildlife (CPW) to see what they had to say.
Their recent electroshocking data confirms my hypothesis. CPW surveys two different stretches of river near Deckers—one above town and the other a third of a mile below. The end result is that the trout populations have been on a steady rise since 2010, despite an increase in fishing pressure. Catch-and-release works! The most recent data was collected in 2019. (CPW did not electroshock in 2020 due to Covid-19.) The data shows that there are 4,482 fish per mile above Deckers, and 9,705 fish per mile below.
Above Deckers, 69 percent of the fish collected were brown trout, with rainbow trout and cuttbows making up the balance. The station below Deckers was even more impressive, with brown trout making up 73 percent of the biomass. Rainbows, cuttbows, plus a few longnose and white suckers were the minority.
My guess is that recent drought years with lower outflows from Cheesman Dam and warmer water temperatures have created ideal conditions for brown trout to propagate. Now that the brown trout have taken a strong foothold, they are out-competing the rainbow and cuttbow populations.
That’s not to say that you won’t catch some nice rainbows. Some of the biggest rainbows of the year are caught during the winter because savvy anglers are able to spot and stalk (sight fish) them when the river levels are low. When the river rises in the spring due to an increase in downstream demand and spring runoff, these bigger trout are lost in the shuffle and are much harder to target.
Classic South Platte Flies
Some of the most popular trout patterns of all time were created for the South Platte River near Deckers. Gene Lynch and his buddies Ken Chandler and Tug Davenport carved their way into angling history by designing the South Platte Brassie back in 1960s. The Brassie originated during one of their routine tying sessions when they came up with the idea of wrapping copper wire around a hook shank to provide additional weight on some of their favorite nymphs.
The story is told that one of their “weighted nymphs” came apart after catching several fish on it, but to their surprise, they kept fooling fish on the shiny copper wire underbody. Based on their success, Lynch, Chandler, and Davenport decided to add a small piece of black heat-shrink tubing for the head and call their new concoction the South Platte Brassie.
In recent years, fly tiers have used a variety of materials for the thorax and head, including gray or black dubbing, peacock herl, or a few wraps of gray or black tying thread. My personal favorite is gray Superfine dubbing for the thorax with gray 8/O UNI-Thread for the head.
Ed Marsh developed the Miracle Nymph back in the early 1970s to imitate the abundant cream-colored midge larvae near Deckers. Marsh’s pattern is a great example that “less is more” when it comes to designing trout flies.
The original Miracle Nymph was tied with a black thread underbody overlaid with white thread and copper wire for a rib. The black color bleeds through the white thread, producing a cream-colored abdomen. The final step is a few wraps of black tying thread behind the eye of the hook to produce a prominent head.
Most modern tiers forgo the black thread underbody and simply use white thread and copper wire for the abdomen. The rest of the tying recipe is the same. In either scenario, the Miracle Nymph has been plucked by selective trout near Deckers for over 50 years.
Marsh is also known for developing the Buckskin, another important pattern for anglers who frequent the Deckers area. While the Buckskin is most often used as a caddis larva, it’s also deadly in sizes 20 to 24 for imitating cream-colored midge larvae. The original Buckskin recipe calls for a brown hen tail, but most tiers omit the tail (or clip it off) when they use it to imitate midge larvae. The abdomen is tied from a thin strip of chamois wrapped tightly around the hook shank and secured with black thread.
Rim Chung’s RS2 also surfaced in the early 1970s and is perhaps the most famous fly to originate near Deckers. RS2 stands for Rim’s Semblance number 2. Its predecessor was the RS1, which had a wingcase instead of an emerging wing. Although Chung’s pattern was originally designed as a mayfly emerger, it’s hard to go wrong with a size 22 or size 24 RS2 to imitate midge pupae during the winter month. Chung’s RS2 and its variations have probably caught more trout in the South Platte watershed than any other pattern.
Several other flies have become popular in recent years: Greg Garcia’s Rojo Midge, my Black Beauty and Top Secret Midge, Greg Blessing’s Purple Haze, and Charlie Craven’s Jujubee Midge. These patterns were designed out of necessity by a new wave of talented tiers taking the midge game to the next level.
Charlie Craven explains the driving force behind his Jujubee Midge: “I developed what was then known as the Super Midge to match that olive and black midge up in Deckers and Cheesman Canyon. This was back when I was guiding a lot in the early 1990s. I had been using an olive Miracle Nymph, but I wanted something that matched the hatch better. When I submitted the Super Midge to Umpqua Feather Merchants, they told me I needed a better name, so I named it Jujubee Midge after my daughter, Julie. I happened on the Super Hair technique by accident when tying barracuda flies and used it to create the variegated body for a midge pattern.” Craven shows how to tie the his Jujubee Midge, as well as the Black Beauty, the RS2, and many other patterns on the Fly Fisherman magazine YouTube channel.
The Manhattan Midge, developed by my son Forrest Dorsey, is one of the latest trending midge patterns that is designed for the finicky trout that reside near Deckers. According to Dorsey, “The Manhattan Midge is a souped-up hybrid of my father’s Top Secret Midge, Mercury Black Beauty, and Mercury Blood Midge that incorporates the best attributes of each pattern. It has a slim profile, segmented body, a flashy wing, peacock collar that breathes life, and a clear silver-lined bead to mimic the trapped air in the thorax during a midge’s emergence.” The Manhattan Midge has no doubt created a lot of buzz over the past few years because it gets the job done day in and day out.
Whether you’re using one of the “oldies but goodies” or trying some of the new cutting-edge patterns, all of these flies should be worthy of a spot in your fly box. I recommend stocking them in sizes 18-24 so that you’ll be prepared for a variety of situations.
South Platte Brassie
The South Platte River near Deckers is in a league of its own when it comes to tailwater fisheries. I hope you get a chance to fish it for yourself and see what all the hype is about.
Pat Dorsey is a co-owner of Blue Quill Angler and has been a guide on the South Platte River for more than 25 years. His most recent book is Fly Fishing Guide to the South Platte River (Stackpole Books, 2019).