In this report
107 CFS in August: Low Water, High Stakes
The gauge is reading 107 CFS, and that matters more than usual right now. On the Pueblo tailwater in midsummer, that’s not a sweet spot—it’s a warning sign. At this flow, thin water heats fast under August sun, and the trout know it. Every afternoon the temperature climbs, and by mid-day the fish retreat to the deepest, slowest slots they can find. You need to fish deliberately, early, and with genuine concern for the water’s welfare.
Carry a thermometer. If you’re reading this and planning to drive down, check the live flow chart before you leave—these releases swing violently (42 to 177 CFS in two weeks is not rare here), and what the gauge says today may not match what you find on the water. But more important than flow volatility this week is water temperature. In August at 107 CFS, Pueblo tailwater gets thin and vulnerable. Fish the coolest hours: dawn until mid-morning, then again from late afternoon into dusk. If the thermometer hits the mid-60s during the day, step back off the water entirely. These brown and rainbow populations are strong, but summer heat plus low flow is a genuine stressor.
Where the Water Actually Holds Fish Right Now
At 107 CFS, the river is compressed. The flat, sunlit margins you’d pick at higher water are now hot, clear, and nearly empty. Every trout of consequence is stacked in the deep inside bends, the darker slots below any structure that creates a current break, and the plunge pools where one channel drops into another. These are your only targets. The thin flats are a waste of time and energy—and frankly, a waste of the fish’s patience too.
Focus on the deep holes that run tight against the banks, especially on the outside of bends where the current does the work. Where you see the water darken, where it moves with intention even at this low flow, that’s where the holding water is. The trout are not ranging; they’re locked down, finicky, and spooky because the whole river is gin-clear and they’ve got nowhere to hide.
The Hatch Window: Midges and Tricos, Nothing Else
August on Colorado’s tailwaters runs on two clocks: the evening caddis (which is present, but secondary right now) and the small morning hatches that dominate Pueblo’s reputation. Midges—zebra midges, black beauties, Mercury Midge emergers—are your baseline. They’re here every day, size #20–24, and you’ll find adult activity from first light through mid-morning. Fish the black emergers subsurface on a tight-line or a light indicator in the deeper slots.
The real pull this week is the Trico spinner fall. Tricos (#20–24) hatch in low light early in the morning, and the spinner fall—when spent females drop back to the water—is a focused, often violent event in the first hour or two after sunrise. At 107 CFS, that fall is even more concentrated than usual. The trout are not roaming; they’re posted in specific seams waiting for spinners to drift into their window. If you’re not there at first light, you’re missing the best dry-fly window of the day.
Afternoon brings caddis—tan and gray, size #14–16—but the activity is muted at this low flow and low water. Fish caddis patterns if you see adults, but don’t hang your whole day on it.
The Rig: Specifics for Clear, Shallow Water
At 107 CFS with gin-clear water, you need to go small, light, and long on the tippet.
For the Trico spinner fall (sunrise, 6X or 7X tippet): Use a dry Trico spinner pattern, size #22–24, with 18–20 inches of 6X or 7X below your main line. No indicator, no split shot—just drag-free float. The water is clear enough that trout will see a heavier tippet and refuse. Expect refusals; make delicate casts, and give the fly room to drift naturally.
For subsurface midges and nymphs (all day, but especially mid-morning through mid-afternoon): Rig a double nymph. Start with a small #20–24 zebra midge or emerger as your point fly. Add a #18 PMD emerger as your upper dropper, hung 18 inches above on a tag of 5X. Use a single small split shot pinched on the main line, 12–14 inches above the upper dropper. This rig gets you down without over-weighting; the light shot ticks the bottom of the deep slots without snagging constantly. Fish it on a tight-line or under a small indicator (use a yarn or foam indicator no bigger than a pea—the water is clear, and a big bobber will spook fish).
Tippet size matters here more than on higher flows. At 107 CFS, 5X and 6X are your baseline. Go lighter for the small stuff (#20–24), heavier (5X, maybe 4X) only on the larger dropper or when you’re slinging caddis. The gin-clear water gives every knot and every thickness away.
Water Access and Fish Welfare
The Pueblo tailwater through the city and below is accessible, but respect the regulations in the upper reaches closest to the dam. This is a special-regulation tailwater—verify the current regs for the exact section you plan to fish, but be ready for artificial flies and lures only, with trout over 16 inches released (not full catch-and-release), in the most restrictive stretches. The Colorado Parks and Wildlife website is your source; those regulations shift, and this week is not the time to guess.
More urgent: if the water temperature gets warm, stop fishing. A #20 midge or a tiny Trico spinner is a small thing, but a stressed trout in thin, warm water is a real problem. Fish the edges of the cool holding water, not the open shallows. Dawn and dusk are not luxuries this week—they’re the boundary between a decent day and a harmful one.
107 CFS is a reminder that the Pueblo tailwater’s true strength shows in winter, when flows stabilize cold and low and the fishing is consistent and ethical. In August at this level, the fishing is possible but precarious. Go early, stay small and delicate, keep the thermometer handy, and respect what the water is telling you.