In this report
Flow is Low and the Water is Warming — Fish Accordingly
At 107 CFS, the Pueblo tailwater is running well below the summer healthy threshold and squarely in the territory where you need to think carefully about fish welfare before you fish hard. This is not a “low but fishable” reading the way winter low flow (70–150 CFS) fishes well on cold water. In early June heat, thin water warms fast in the sun, and trout get stressed. Carry a thermometer. If you’re finding water in the mid-60s°F or above by mid-morning, dial back or shift to dawn and dusk fishing when the water is coolest and the trout are most willing to feed.
The consequence for wading is simpler: at 107 CFS you can cross the main channel without drama, but you’ll feel the loss of volume. The big deep slots and inside bends that normally hold fish through the summer are still there, but the water around them is shallower and brighter. Trout will be tucked into those deeper runs and under bank shadows more than usual. The gin-clear water means fish are spooky — expect longer tippet and smaller flies than you might otherwise throw.
Check the flow chart before you drive down. This tailwater’s releases are volatile. A reading of 107 today can swing to 150 or drop to 60 within days. What you see on the gauge now may not match what you find when you arrive.
Pale Morning Duns Dominate, But Fish Them Small
June is PMD season on tailwaters across Colorado, and the Pueblo is no exception. Pale Morning Duns (Ephemerella, #16–18) will be your primary dry-fly target, with peak emergence running late morning into the early afternoon. The nymphs are already moving in the water column, and both the emerger stage and the dun itself will draw aggressive takes.
But here’s the critical detail for this water at this flow: go smaller on your dry-fly sizes than you might on a higher, more forgiving flow. At 107 CFS with gin-clear water, trout are keyed in on detail. A #18 PMD dun will be more productive than a #16, and a realistic taper matters — avoid overstuffed or blocky duns. Comparadun-style wings and a lean body will draw better takes than a fat parachute.
The emerger bite is often stronger than the dry during the peak window. A #18 PMD emerger fished in the film or just under will often outfish a dry, especially on days when the hatch is prolific but surface takes are slow. Fish it on a dead drift or with a subtle inch-and-pause retrieve as the nymphs transition.
Caddis will also be present — #14–16 tan and olive patterns in the evening — but the hatch is secondary to the PMD activity. Expect the caddis to come off after 5 p.m., and if you stay for the evening session, have a few in your box.
Subsurface: Midges + Emergers in a Two-Fly Rig
Midges are the year-round heartbeat of the Pueblo tailwater, and in June they’re working all day. Black Beauty, Mercury Midge, and zebra midge patterns in #20–24 will catch fish constantly, especially in the slower seams and behind boulders where current slows.
Your core rig for this week should be a subsurface anchor + dropper setup. Tie a heavier midge or small nymph (a #22 Black Beauty or a Barr’s-style #20 nymph in brown or black) as your anchor fly, weighted with a small tungsten bead. Add 12–18 inches of 5X tippet above it and tie on a #18 PMD emerger as your dropper — this is where the takes often happen during the hatch window.
Weight it to fish the bottom of the deep runs. If you’re fishing a 9-foot leader on 5X, add a small split shot 8–10 inches above the anchor fly to get the rig down quickly and keep it working the zone where trout are holding.
The water is clear enough that a small indicator works, but tight-line nymphing with a short 6–7 foot leader can be deadly on this water if you’re experienced with it — less drag, and you’ll feel the strike faster on light tippet. If you go tight-line, stay ready to set gently; 5X tippet on small emergers doesn’t forgive a hammer.
Fish the deep inside bends, the tailouts of pools where current slows, and the seams along the banks. The thin water means fish are concentrated — they’re not scattered across the shallows. Work the likely holding water deliberately rather than covering a lot of ground.
Water Types Worth Your Time This Week
The deep slots below faster water are the prime zones. These are the transitions where water drops into a run 3–4 feet deep and slows slightly — exactly where trout retreat when water is warm and thin. Fish these with a controlled drift, letting your emerger and anchor work the seam naturally.
Bank shadows, especially on the south-facing side of the channel where morning and afternoon sun are intense, will hold trout seeking cooler water. These are often skinny, but the fish there are active feeders because they’re trying to intercept food in the moving current without leaving the shade. Short, precise drifts work better than long ones.
Avoid the shallow flats entirely. In 107 CFS of warm water, they’re a waste of time. The fish aren’t there.
One Stewardship Note
If the water hits the mid-60s°F, stop. Fish dawn and dusk only, and seriously consider not fishing at all if you’re seeing consistent readings above 65°F. This tailwater’s big browns and rainbows are resilient, but they’re also under stress in warm, thin water. Catch-and-release is better practice than it is therapy in these conditions — the fish need the energy you’re costing them.