In this report
Flow is Low and Warm — Fish Accordingly
The Arkansas River below Pueblo is running at 107 CFS right now, and that’s a real problem this week. We’re deep into June heat, and at that volume, this tailwater warms fast. The good news: you can still catch trout, but only if you fish smart and put fish welfare first.
Here’s the context: in summer, the Pueblo tailwater struggles below 70 CFS. You’re at 107, which is marginally better than crisis, but it’s still low for early June. The thin water column heats up quickly once the sun gets high. Air temperature and sun exposure become your limiting factors faster than the hatch does. Carry a thermometer. If the water climbs past the mid-60s, the trout are stressed, and you should stop. Early morning and evening sessions—say, 6 a.m. to 9 a.m. and 6 p.m. to dark—are your real windows. Midday fishing is not a good idea this week.
That said, the flows are stable at the moment. Before you drive down, check the flow chart on this page: swings on the Pueblo tailwater can be violent and sudden. A 107 reading today can become 60 or 200 CFS inside days, depending on what Pueblo Reservoir operations decide. If the number has shifted materially by the time you leave your driveway, reassess—low flows get worse fast, and high summer flows can muddy the water and kill the bite.
Pale Morning Duns and Gin-Clear Spookiness
The PMD hatch is running, and it’s your primary focus from about 10 a.m. through early afternoon—though the window is narrow in this heat and low water. Expect emergences in the #16–18 range, Ephemerella-style. The bugs hatch in fits, not blankets, because the thin water doesn’t have the thermal mass to support a sustained emergence. Fish that do show up are concentrated in the best holding lies and spooky as hell.
Caddis will appear in the evening, #14–16, mostly in that magic hour before sunset when the water cools slightly. And midges—the year-round workhorse of this tailwater—are active all day in #20–24 sizes. Midge emergers and small nymphs will often outfish the mayfly dries, especially in the gin-clear low water.
The clarity is your tactical challenge. At 107 CFS and low gradient below the dam, the water is translucent. Fish see you. Fish see your leader. Fish see your tippet knot. Long leaders are mandatory: 9 feet of 4X or 5X down to a 4–5 foot tippet of 6X or 7X. The drag-free drift matters more than your fly choice. Sloppy casting will shut down fish fast.
Rig for the Deep Slots
Low flows concentrate trout. Forget the shallow, sunlit flats—they’re warm and barren in this season. Fish the deep slots and inside bends where current scour has carved out cold-water refuges. That’s where the trout are holding, and that’s where you spend your time.
For nymphs, use a two-fly rig: a heavier anchor fly—a Barr’s Spawn, Barr’s Emerger, or small tungsten bead nymph in dark colors—on the point, and a lighter, more realistic emerger trailing 12–18 inches above on a 4X dropper. Weight the rig to tick the bottom without snagging constantly. At 107 CFS, you don’t need heavy tungsten; a single BB split shot pinched 8–10 inches above the point fly will do. Fish this rig tight-line or under a small indicator, depending on the depth of the slot and your confidence in feeling the take. Long drifts through the cold pockets will outfish short, aggressive probing.
For dries during the PMD emergence, stay on the tippet long: 5–6 feet of 6X minimum. A #16 or #18 PMD emerger, fished in and around the current breaks at the head and tail of the deep slots, will draw strikes. Expect refusals from spooky fish; if a trout looks at your fly and turns away, it’s usually your tippet or drag, not the fly. Make another cast 3 feet upstream and let it drift naturally.
For evening caddis, switch to a #14–16 tan or brown dry, fished the same way: long leader, delicate landing, and position yourself to avoid lining the fish. The evening bite is often the strongest part of your day in this heat and low flow—the water cools slightly, fish rise more freely, and you can cover more water with dries than you can with nymphs.
Midge fishing—small #22–24 black or zebra patterns—is your insurance policy. When the mayfly hatch falters or the caddis are late, midges will be eating, and a small emerger fished just below the surface in the film often draws subtle but reliable strikes. This is not flashy fishing; it requires attention and patience, but it will produce fish when other tactics don’t.
What This Water Actually Demands
The Pueblo tailwater below the dam is a precision fishery, especially at low summer flows. It rewards the angler who thinks like a trout in thin, warm water: early, late, deep, cold, and careful. The fish are there—special-regulation protection and a year-round population of big browns and rainbows see to that—but they’re not aggressive, and they’re not forgiving.
Don’t assume the hatch will save you. At 107 CFS in June heat, the hatch is a small part of the picture. Fish welfare, water temperature, and stealth are the larger story. Wade slowly and deliberately; disturb the water as little as possible. Fish the lies, not the current. Stop early if the water gets warm. And before you commit to the drive, verify the flow hasn’t blown out or dropped into crisis territory. This river can surprise you fast.