The Hour Before Coffee on the Dream Stream
The first time the Tricos really got me was on the Dream Stream below Spinney, an August morning so still the only sound was the click of my reel. I had walked in at first light expecting to nymph the morning away, and instead I stood ankle-deep watching the world’s smallest mayflies drift overhead in clouds. By six-thirty there were spinners dropping into the slow water at the head of the run. By seven, every fish above twelve inches was sipping in a steady, metronomic rhythm I have only ever seen during a Trico fall. I missed three before I tied on a size 22 spent-wing and figured out the timing. The trico hatch Colorado tailwater anglers chase all summer is a different kind of fishing — small bugs, light tippet, and a hatch that is mostly over before most people have finished breakfast. Get the timing right and you can have the best dry-fly water in the state to yourself for two hours, every morning, for two months.
When the Trico Peaks in Colorado
Trico (Tricorythodes) is almost exclusively a tailwater event in Colorado, and the windows are remarkably consistent from one river to the next. The hatch begins building in mid-July as water temperatures stabilize above 55°F through the night, ramps to peak intensity through August, and tapers across September. A few productive mornings continue into early October on the warmer tailwaters.
Tailwater Windows
| River | Prime Window | Daily Peak | Hatch Sequence | Hook Size |
|---|---|---|---|---|
| South Platte — Cheesman Canyon | Jul 15 – Oct 15 | 7 – 10 a.m. | Dun emergence at dawn, spinner fall by 8:30 | 18-22 |
| South Platte — Dream Stream | Jul 20 – Sep 30 | 8 – 11 a.m. | Spinner fall dominant; slow-water sippers | 20-22 |
| South Platte — Deckers | Jul 15 – Oct 15 | 9 a.m. – noon | Slightly later than Cheesman; longer dun window | 18-22 |
| South Platte — Eleven Mile Canyon | Jul 15 – Oct 15 | 11 a.m. – 2 p.m. | Tailwater cooling delays everything ~2 hours | 18-22 |
| Frying Pan below Ruedi | Aug 1 – Sep 30 | Before 10 a.m. | Spinner falls in slow flats; very small bugs | 18-24 |
| Arkansas — Pueblo Tailwater | Jul 15 – Oct 15 | 8 – 11 a.m. | Extended window into late fall | 20-24 |
Two patterns stand out. First, every productive Trico water in Colorado is a tailwater — the steady, cool flows from bottom-release dams keep the substrate stable enough for Trico nymphs to thrive through the summer. Freestone rivers do not produce meaningful Trico hatches in this state. Second, the daily window shifts predictably with water temperature: cold tailwaters like Eleven Mile push the peak into early afternoon, while sun-warmed sections of the lower South Platte fire by sunrise. Always check the Colorado Parks and Wildlife fishing regulations before your trip — several of these tailwater stretches carry catch-and-release-only, flies-and-lures rules.
Best Flies to Match the Trico
Trico anglers fail more often from fly size than fly shape. Colorado Trico spinners run 18-22 on tailwaters like Cheesman and Dream Stream and drop to 22-24 on the Frying Pan and lower Arkansas. If your size 18 is getting consistent refusals, drop two sizes before changing patterns.
Surface patterns (spinners, duns, and emergers):
- Hi-Vis Trico Spinner, sizes 20-22 — white poly wing makes a 22 visible on flat water
- Spent-Wing Trico, sizes 20-24 — low-riding profile for educated sippers
- CDC Trico Spinner, sizes 20-22 — buoyant on slow tailwater glides without floatant
- Female Trico (green egg sac), size 20 — overlooked but deadly during egg-laying flights
- Parachute Trico, sizes 18-22 — visible during the dun window before spinner fall
- Sprout Trico, sizes 20-22 — emerger that sits half in the film, kills early in the hatch
- WD-40 (olive or black), sizes 20-22 — pre-hatch dropper for fish already keyed up
The spinner stage does most of the work, but the hour before the fall is when the dun and emerger flies earn their keep. Trout transition to surface feeding gradually as the first duns punch through the film, and an emerger pattern fished in those first thirty minutes will outproduce a spinner that is still ten minutes too early. Below the surface, the nymph migration starts before sunrise, and fish keyed up on tiny mayfly nymphs will eat a small dropper for an hour before any wings appear on top.
Subsurface patterns (nymphs and droppers):
- Black RS-2, sizes 20-22 — primary Trico nymph imitation, fish it 18 inches under any dry
- Top Secret Midge, sizes 22-24 — crossover pattern that doubles as a tiny Trico spinner
- Mercury Black Beauty, sizes 22-24 — point fly for the hour before the spinner fall
Carry duplicates of every spinner pattern. You will lose flies to 6X breakoffs and you will mash hackle on every fish that eats deep — being able to retie identical at sunrise without rummaging matters more than carrying more variety.
Top Rivers for the Trico
The four-section South Platte tailwater system is the marquee Trico water in the state. Cheesman Canyon is the technical benchmark — clear water, wild fish, long leaders required. Walk the canyon trail at first light, position downstream of feeding lanes in the slow tailouts, and fish a size 20 spent-wing on 6X. The Dream Stream between Spinney and Eleven Mile reservoirs is the most consistent Trico water for spinner-fall purists; the gradient is gentle, the bugs concentrate in the slow bends, and pods of fish line up sipping for two hours straight. Deckers is the friendliest section for anglers learning the hatch — bigger water, more forgiving drifts, and a window that often runs past 10 a.m. Eleven Mile Canyon runs cold and runs late; if you missed the Dream Stream window, drive thirty minutes south and pick the hatch back up at lunch.
The Frying Pan below Ruedi produces Trico fishing on a different scale — bugs as small as size 24, fish that have seen every imitation, and a window that often closes by 9:30 a.m. The flats below the dam concentrate the spinner fall, but expect drag-free 15-foot leaders and 7X tippet to be the price of admission. The Arkansas River through the Pueblo Tailwater is the dark horse — extended Trico activity into late fall, less crowding than the South Platte, and warm enough through the morning that the hatch builds slowly rather than firing all at once. Smaller productive Trico water exists on the Williams Fork tailwater and the Big Thompson below Estes, both worth scouting if you can stand a 4 a.m. alarm and a long drive.
How to Fish the Trico
A Trico morning has three distinct phases and your rig has to match. Phase one is the dun emergence, generally from first light to about an hour after sunrise. Trout key on cripples and stuck-shuck emergers during this window because perfectly hatched duns are airborne in seconds. Fish a Sprout Trico or a parachute on top with a Black RS-2 dropper on 12 inches of 6X — most takes come on the dropper while you watch the dry.
Phase two is the spinner fall itself, typically thirty to sixty minutes of intense feeding that starts when the air clouds of mating Tricos begin dropping to the water. This is where most anglers struggle: the fish are everywhere, rising rhythmically, and looking past anything that does not lie flush in the film. Switch to a Hi-Vis Trico Spinner or a CDC spent-wing, drop tippet to 6X or 7X, and lengthen your leader to twelve feet minimum. Pick one rising fish, watch its rhythm for three full feeding cycles, and deliver the fly two feet upstream of its last rise. Casting at every splash is how you blow a Trico morning. Patience and target selection are how you save it.
Phase three is the late-morning lull — the spinner fall ends, the dispersed fish quit working, and most anglers leave. Stay another hour. The fish that fed hardest are now stationed in the same lies digesting, and a dead-drifted Top Secret Midge or a Mercury Black Beauty on 6X will pick off the biggest ones in any given pod. Many of my best Trico-day fish have come between 11 a.m. and noon, not during the hatch itself.
Check Live Conditions Before You Go
The FlyGuysNLies app shows real-time flows and fishing verdict for every river — pull up River Conditions before you leave the driveway.
The app’s Hatch Charts also track Trico emergence intensity by river so you can see whether Cheesman is firing this week or whether the Dream Stream is still building. Pin your Trico waters as Favorite Rivers and log every hatch session in Fishing Reports — two summers of entries turns intuition into pattern recognition, and next year you will know the Dream Stream spinner fall starts within ten minutes of the same time each morning without having to guess.
Making the Most of the Two-Hour Window
The trico hatch Colorado tailwater season rewards anglers willing to lose sleep, and once you have one good morning under your belt, the trico hatch Colorado calendar starts dictating the rest of your August. Be on the water with a rig already tied and a backup leader in your pocket by first light. Carry magnifiers if your eyes are over forty — threading a size 22 in low light at the start of the spinner fall is not the moment to fumble. Match the size before the shape, fish 6X or 7X without apology, and treat every refusal as a tippet message before you change patterns. Trout Unlimited’s Colorado chapter does the work of protecting the tailwater flows that make these hatches possible — their advocacy is worth supporting, and the South Platte fishery in particular owes them a lot. Two hours of perfect dry-fly water, sixty mornings a year, with the rest of the state still asleep. There is not much in fly fishing that beats it.
