In this report
107 CFS and a Water-Temperature Warning
At 107 CFS, the Pueblo tailwater is running thin—well below the summer sweet spot and approaching the threshold where trout welfare becomes the lead story. Before you load the truck, understand what you’re walking into: this is low summer flow on a dam-controlled water that heats fast in the thin column. The gauge reading you see right now may not hold; Pueblo’s releases swing dramatically day to day, so verify the live flow chart before you drive down. But whatever the current number, understand that at this flow and this time of year, water temperature is the controlling factor.
Carry a thermometer. If the water climbs past the mid-60s, stop targeting rising fish and shift to nymphing in the deepest, coldest holding water—the plunge pool immediately below the dam and the long dark slots where the channel cuts deep and shaded. Trout are already stressed in thin, warm water; you’re not helping by keeping them on the rise during the heat of the day. Fish early and late, when the air is cooler and the water hasn’t had eight hours of sun beating down on it.
The thin flow does concentrate fish into fewer places, but it also makes them spooky. Expect to work harder for every take.
What’s Hatching This Week
August on the Pueblo tailwater runs on midge, small mayfly, and caddis—the calendar hatches that don’t care about dam releases or air temperature, they just happen because it’s midsummer.
Midges are the foundation. Black Beauty, Mercury Midge, and zebra midge emergers in #22–24 should be in your box, fished deep on a dead drift or tight-line rig. Midges hatch all day in small, scattered pulses; they’re not the explosive spinner fall of winter, but they’re consistent and they’re always worth a cast. Fish them 18 to 24 inches below a small split shot in the soft current along the seam where current meets slack water.
Tricorythodes spinners (Tricos) come off in the early morning—typically dawn to mid-morning—as tiny #20–24 black spinners. If you’re on the water at first light, watch for the spent-wing fall in the slow, smooth water near the banks and in the long glassy tailouts. These spinners are small enough that they look invisible on the water, but trout key on them hard. Fish a #20–22 black spinner imitation dead-drift in the film, or go slightly upstream with an emerger and let it drift down through the feeding zone.
PMDs (#18) continue in small numbers through the afternoon. They’re not a dominant hatch in August, but they’re present, and a #18 PMD emerger or nymph can produce all day in the deeper runs. Rig it as a second fly below a midge anchor.
Caddis in the evening: Tan and olive caddis (#16–18) begin to show around dusk. Fish them soft-hackle or as dry flies in the faster current seams where the water is most oxygenated. Evening hatches often produce the most aggressive takes of the day—fish are less spooky in low light, and caddis bring up good fish.
Terrestrials (ants, beetles, small hoppers #12–16) should be in your pocket during the warm part of the day. They’re not a “hatch,” but they’re what trout see falling into the water during a hot August afternoon. When nothing is rising, a small black ant or a #14 hopper drifted along the bank can be the key.
How to Fish It at 107 CFS
At this flow, the water column is thin and gin-clear. Your presentation needs to match. Trout can see you, your line, and a poorly tied knot. Tie small knots and be honest about your leader.
Upper reaches closest to the dam: This is the most productive water, and it’s also the most regulated. The special-regulations stretch runs artificial flies and lures only, with trout over 16 inches released (not full catch-and-release). Verify the current specific boundaries and bag limits before you fish—they can shift year to year and vary by sub-section. Your advantage here is predictability: controlled releases, steady cold water, and big browns and rainbows that have nowhere else to go. Work this water with discipline and respect, and it will reward you.
Rigging for depth in thin water:
- Use a small tungsten nymph (Barr’s Graphic Caddis, Mercury Black Beauty, or a beadhead Hare’s Ear #20–22) as your anchor.
- Tie a 12–18 inch dropper of 5X or 6X tippet to the bend of that hook.
- Add a #22–24 midge emerger or PMD emerger to the dropper.
- Add one small split shot 8–10 inches above the anchor fly, or go weight-free and fish it on a tight-line rig if the current is slow enough to maintain contact.
- Fish with a 7X tippet from your leader to the point fly on the Tricos and tiny midges—yes, 7X will cost you occasional fish, but at 107 CFS and this clarity, 6X is still too thick on a #22 hook.
Where to fish:
- Deep slots and the plunge pool: These are your priority in warm, thin water. The water is coldest deepest, and trout are holding tight to the bottom. Nymph these places with a dead drift or tight-line rig, no indicator. Count your fly down, feel for contact, and watch your leader for the subtle twitch that means a take.
- Current seams where fast water meets slack: Trout sit in the slower water just off the main flow, where food drifts past but they don’t expend energy fighting the current. A 3–6 foot drift through these seams with a light nymph rig will find most of your fish.
- Shaded banks and overhanging structure: In low, warm water, trout seek cover and shade. Fish tight to the bank, under willows, in the shadow of a big rock. Your fly needs to drift right to where the trout are hiding.
- Skip the thin, sunlit flats. At 107 CFS and warm-ish water, the flats are too thin and too exposed. Fish will be in the deep, cool, dark water. Don’t waste time in the bright spots.
Stewardship: Know the Regs, Fish Smart
The Pueblo tailwater is a special-regulation tailwater, and it deserves care. At low summer flow and warm water, every fish you land is a stressed fish. Use barbless hooks or crimp your barbs. Land fish quickly, keep your hands wet, and release them gently back into deep, cool water. If the water warms above the mid-60s, stop fishing the surface and keep your focus on nymphing in the coldest water you can find.
Before you fish the upper section near the dam, confirm the current regulations for that stretch. The flies-and-lures-only and over-16-inch-release rules vary by exact location and can change. A few minutes online now saves you a confusing conversation with a CPW officer later.
Get on the water early, fish the deep cold water, and respect the fact that this river, at this flow and this temperature, is a privilege, not a playground.