Yellowstone at 710 cfs: Wade Window Open as Caddis Hatches Build

What's Biting

What's Next

With gauge 06043500 holding at 710 cfs, wade anglers on the Yellowstone are working with favorable conditions — but the clock is ticking. Snowpack in the Absaroka and Beartooth ranges will begin releasing in earnest through mid-May, and flows on this stretch of the river historically rise sharply after the second week of the month. Plan your wade and float trips in the next seven to ten days while clarity and depth remain manageable.

The caddis emergence is the timing window to build your schedule around right now. Per Hatch Magazine's coverage of Yellowstone hatches, caddis can produce intense adult flights once afternoon water temperatures push into the mid-50s°F. No temperature reading is available from gauge 06043500 today, but that threshold is typically reached on this river in early to mid-May. Watch for caddis cases attached to streamside rocks — they're a reliable field indicator that hatches are about to fire. When surface activity begins, soft-hackles or elk hair caddis in sizes 14–16 during the afternoon window are the standard play.

Subsurface remains the bread-and-butter approach until dry-fly conditions develop consistently. Nymph rigs with caddis larva and pupa imitations fished tight to the bottom will produce brown trout and cutthroat in riffles and seams at 710 cfs. Streamer anglers should prioritize the low-light windows that the waning gibbous moon phase favors — dawn and dusk edges near undercut banks and deeper slots.

On the Missouri River tailwater, conditions are typically more insulated from runoff swings than the freestone Yellowstone. Trout below Holter Dam should be responding to caddis and pale morning dun nymphs drifted near the bottom, with afternoon dry-fly windows opening on warmer days. The Missouri's regulated flows make it the dependable backup option if the Yellowstone begins to rise and color.

**Access reminder:** Grey Bear FAS on the Yellowstone River remains partially closed through approximately May 21, per MT FWP Fishing News. Secure alternate launch and takeout points before finalizing float logistics. Check current PFAS consumption advisories at myfwp.mt.gov before keeping fish from any Montana waterbody.

Context

Early May sits at the inflection point between the Yellowstone's most fishable spring conditions and the high-water runoff that typically shuts down wade access by late May. Historically, flows on this stretch remain manageable through the first half of the month, then escalate as accumulated snowpack releases across the Absaroka and Beartooth drainages. A reading of 710 cfs is consistent with normal-to-low pre-runoff conditions for this time of year — by any seasonal benchmark, the river is currently fishing well.

Caddis emergences are one of Montana fly fishing's most anticipated annual milestones. Hatch Magazine, in its feature on Yellowstone hatches, notes that understanding emergence timing underpins angling success on this river — a principle that has held since these hatches were first systematically documented for western anglers. Montana's caddis season typically runs late April through July, peaking in May on the Yellowstone's warmer middle reaches. Field & Stream's recent guide to aquatic insects for trout anglers reinforces that caddisflies rank among the four foundational hatch groups any serious trout fisherman should know — and May is precisely when they matter most in this region.

The Missouri River tailwater, by contrast, is a year-round fishery that hits one of its prime windows in May. Stable regulated releases from Holter Dam combine with building insect activity to make the Craig stretch productive well before freestone rivers peak — and often well after they've blown out. Historically, May on the Missouri draws visiting anglers specifically to intercept consistent dry-fly opportunities ahead of summer crowds.

MT FWP's 41 proposed regulation changes for 2027–2028 are part of the agency's standard biennial review cycle; nothing in the current release signals emergency closures or major harvest changes for this season. The newly released PFAS consumption advisories represent updated guidance from recent sampling, not a new contamination event, and apply to specific waterbodies rather than the region broadly.

No gauge temperature data is available to benchmark this May precisely against prior years. The 710 cfs flow reading is the primary objective reference point for this report.