In this report
107 CFS and the Midsummer Squeeze
At 107 CFS, the Pueblo tailwater is running low for July—well below the several-hundred range that makes for comfortable wading and distributed fish. This is not a winter flow (which fishes beautifully thin at 70–150 CFS because the water stays cold). This is a hot-weather low, and it matters. Air temps in early July push the Reservoir Valley into the 80s and low 90s regularly. Thin water warms fast. Before you drive down, check the flow chart on this page—these releases swing hard day to day, and what you see now may not hold. But if you find 107 CFS when you arrive, plan for gin-clear desperation tactics, not comfort-zone fishing.
The low flow concentrates trout into the deep slots and undercuts closest to the dam and in the scour holes below the city. Wading is easy—almost too easy, because the exposed flats and gravel bars look fishy but hold almost nothing. The holding water is obvious: dark, deep channels where current breaks and depth provides refuge. Fish are spooky at 107 CFS, and the gin-clear water leaves no margin for error. You will see them before they see you if you’re careless. You will not if you’re dialed in.
Water Temperature: Lead with Welfare
Carry a thermometer. At this flow in July, water temps can drift into the mid-60s°F by mid-afternoon, especially if the dam gates stay open and the day is hot. Past 65°F, trout are stressed—their metabolism cranks, their metabolism burns oxygen they can’t easily find in thin water, and they stop eating. Fish dawn and dusk, when temps drop. Skip the 10 a.m.–4 p.m. window if the thermometer climbs past 65°F. If you’re already wet and the temp tops 66°F, make peace with walking. Catch-and-release on stressed trout is not virtuous—it’s damage. The winter fishery on this tailwater is a reason people fish it year-round; respect it by not torching the summer population when conditions don’t support it.
The Hatch Right Now: Midges, PMDs, and Evening Caddis
Midges are the spine of July on the Pueblo water. Black Beauty and Mercury Midge nymphs in #22–24 should be in your box year-round here, but they’re especially critical when the water thins and the trout retreat. Tricos are starting their spinner falls in the early morning hours (5–7 a.m., roughly), #20–24 patterns, females laying eggs. This is a small-fly window and a short one, but the fallout is real, especially if you’re up and wade-in before full sun.
PMDs are still active in the #16–18 range (emerger and dun), spinning in the evenings and hatching through midday transitions. At this flow, the hatch is less concentrated and easier to miss than it would be at higher flows, because the water spreads thinner and bugs don’t stack. But the fish are keyed on them, especially in the deeper slots where the current carries emergers down efficiently.
Caddis in the evening—#16–18 tan and olive—start moving after 6 p.m., peaks around 7–8 p.m. This is your premium dry-fly window on a 107 CFS day. Fish the margins of deep runs where the current edges shallow again and where adult caddis kick out from the water. A simple tan elk-hair caddis or an olive Chubby Chernobyl fished tight to undercut banks will draw takes. But wait until the light softens and the air cools; midday caddis activity is sparse.
Terrestrials—ants and beetles in #14–16—show up on hot afternoons, especially around riparian shade. At 107 CFS, these can work if you’re in the right slots (deep, cool, slow-edge water near overhanging willow or cottonwood), but they’re secondary to the midge-emerger game. Don’t chase them at the expense of the high-percentage stuff.
Rigging for 107 CFS: Depth, Spookiness, and Specifics
The rig is a nymph-and-dropper in clear water, fished tight-line or under a small indicator. Start with a heavier anchor—a #18 PMD emerger or a #22 Mercury Midge on point, 18 inches above a Barr’s Olive or Black Beauty #24 dropper, or reverse it. Add one small split shot pinched onto the tippet 6 inches above the point fly to reach the seam fast without tumbling into the thin water and spooking everything in a 20-foot radius.
Use 5X tippet minimum, 6X preferred on the dropper if you’re confident in your knots. At 107 CFS, the trout have time to inspect, and a thick tippet will cost you bites—more so than it costs you on a bigger, busier water. The gin-clear water is a liability; make the leader and fly work like they’re supposed to.
Fish the deep slots and undercut runs—the plausible holding water. Skip the thin, bright flats. Wade slow, keep your profile low, and cast from the shallows or the bank when possible. A 45-foot cast to a deep slot, laid out soft, will outfish 20 casts to water that isn’t holding anything. Trout are compressed and attentive.
Tight-line nymph (a 6- to 8-foot euro-style rod with a thin leader and no indicator, reading the line for takes) can be devastating at this flow if you can feel it. The lack of an indicator means no visual disturbance, and the long, sensitive rod telegraphs the subtle takes that are all you get in thin water. If you’re skilled at it, it’s the highest-percentage technique here right now.
Access and Stewardship in the Heat
The upper sections closest to the dam offer the coldest water and the best holding habitat at low flows, but special regulations apply—verify the current bag limits and artificial-only restrictions before you fish. These rules vary by sub-section and can shift year to year. Know your water before you cast.
Fish only if the thermometer says it’s safe. A 107 CFS day in July is a test of judgment, not a free pass. The winter fishery will be here in five months and worth protecting.