In this report
97 CFS: Ultra-Technical Water, and Fish Know It
The flow chart reads 97 CFS, and that is the story this week at Cheesman Canyon. We are well below the 250–400 CFS band where this tailwater spreads fish across a healthy range of summer and fall lies. At this level, you are fishing experienced, spooky trout concentrated into the deepest pockets and tightest slots the canyon offers—the kind of water that demands small flies, long leaders, and the kind of patience that separates anglers who belong here from anglers who will leave frustrated.
The upside: this is the water Cheesman Canyon was built on. This is the original arena for light-tippet, small-fly technical nymphing in Colorado. The trout here are wild and large, and at 97 CFS they are not going anywhere—they are locked into their best holding water, where you can find them if you read the granite and glass correctly. The downside is equally real: marginal wading, reduced holding water, and fish that will bolt at a shadow or a careless presentation. There is no margin for error. This is not a week for wide-open, forgiving casting.
Midges and Fall BWOs: The October Baseline
October in the canyon runs on two insects, and both are small. Midges dominate year-round on this tailwater—Black Beauty, Mercury Midge, zebra midge, and RS2 emergers in #20–24—and they do not stop in fall. If anything, their importance deepens as water cools and larger mayflies thin out. Expect midges to be in the water or available every day, in every type of water. They are the safety net when nothing else is rising.
Fall baetis (Baetis—small brown olives, not to be confused with summer PMDs) emerge sporadically on gray days in October, sizing out around #20–22. They are not a guaranteed hatch yet, but watch for them on overcast mornings or afternoons. When they do show, you will see occasional rises in the slower, smoother edges—exactly the kind of water that looks deceptively easy to fish at 97 CFS but requires precision because trout are concentrated there and highly alert.
Brown trout are entering pre-spawn mode, and while you will not see organized spawning runs in the canyon this early, feeding behavior is already shifting toward protein density. Streamers have a place, but save the heavy artillery for early morning or late light when the light-shy fish turn aggressive. Most of your week will be spent on small, weighted nymphs and emergers.
The Rig: Long, Light, and Deep
Here is what works at 97 CFS in Cheesman Canyon:
Start with a 12-foot leader tapered to 5X or 6X tippet. Yes, 5X—this is not a hair-splitting exercise; at this flow, the extra diameter gives you security when trout are short-striking tiny nymphs or when you need to hold a fly tight on micro-drifts through slots. 6X is workable if you are confident in your knot work and your ability to stay calm, but 5X will not spook these fish at this low level.
Rig a heavier anchor fly—a #20 Barr’s Emerger or Mercury Midge in black or dark olive—as your point fly. Add split shot (one or two BB-size) 12 inches above it. Drop a #22 RS2 emerger or tiny baetis nymph 18 inches above that on a 2–4 inch tag of 6X. This gives you weight to reach the bottom of the narrow slots where trout hold, an anchor that can take abuse from the granite, and a smaller, lighter pattern above that responds to the drift and picks up the feeding fish.
Fish tight-line or with a small indicator, depending on water type. In the deepest, tightest slots, tight-line nymphing lets you feel the subtle take before the fish rejects a fake. In the smoother, slower edges—the glass-clear pockets between boulders—an indicator makes sense; it keeps your drift vertical and gives you the split-second reaction time you need when trout refuse 97 times and accept on the ninety-eighth cast.
Water Worth Your Time
At this flow, water type is everything. Skip the fast runs and the obvious current seams—they are holding less water and concentrating fewer fish. Focus instead on the deep slots between the giant granite boulders, the kind of tight, glass-clear pockets where you can see the bottom and see trout holding. These are your A-water this week.
The slower edges on the inside of bends, where current slows and trout can rest without burning energy, are B-water. They will produce, but they demand finer casting and a more disciplined drift because the fish there are exposed and know it.
Skip anything that looks thin or marginal. At 97 CFS, marginal water is truly marginal—not worth the energy or the risk of spooking fish you might find elsewhere.
One Last Thing: Access and Temperature
The Gill Trail hike in is more rewarding than ever at 97 CFS—water is clearer, smaller, and easier to read—but the low flow also means clearer light and warming exposure during midday. Fish welfare is not an acute issue at this level the way it would be at 70 CFS and dropping in late summer, but do not abuse it. If you see fish gasping or hanging in the deepest holes and refusing to feed, it is time to stop and leave them alone.
The trail itself is standard October difficulty. No snow yet, but it is wet and loose in sections. Bring good boots and take your time. This canyon does not reward rushing.