Yakima River Fly Fishing Report - September 20, 2026
YAKIMA RIVER
ReportSEP 20 — 27, 2026
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Flow
1160CFS
YAKIMA RIVER AT UMTANUM, WA
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Water Temp
—
Updated 2026-09-19
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Weather
55–79°F
Mostly Clear
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Clarity
Clear
Check post-storm
Flow is running 1,160 CFS at Umtanum with a gauge height of 31.15 ft — down meaningfully from mid-September levels and dropping, pushing trout off the banks and into deeper seams and mid-channel slots. Clarity is excellent and with sunny skies and a high of 78°F today, expect afternoon terrestrial and BWO action to fire.
What's Working — Hot Flies
Parachute - Blue Wing Olive #22
#22
Juju Baetis Tungsten #22
#22
Top Secret Baetis #16
#16
Bionic Hopper - Tan #12
#12
Bionic Ant 2.0 - Black #16
#16
Egan's Thread Frenchie Jig - Olive #12
#12
Egan's Frenchie #12
#12
Corn-fed Caddis (CDC) Tan #20
#20
Olsen's Hare's Ear Blowtorch Barbless #20 - 28
#20
Tungsten Rainbow Warrior - Extra Heavy #14
#14
Egan's Silver Bullet - Baetis #14
#14
Soft Hackle Pheasant Tail Jig - Barbless #12
#12
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Blue-Winged Olive (Baetis) | 20-22 | Moderate | 11 AM - 2 PM |
| Caddis | 16-20 | Light | 5 PM - 7 PM |
| Terrestrials (Ants & Hoppers) | 12-16 | Moderate | 12 PM - 4 PM |
| Midges | 20-24 | Light | 8 AM - 10 AM |
| PMD (Pale Morning Dun) | 18-20 | Light | 10 AM - 1 PM |
Best Time Window
- 7 AM - 10 AM: Morning midge and early BWO nymphing in deeper runs and seams before the sun hits the water.
- 11 AM - 3 PM: Prime terrestrial and BWO dry-fly window as temps climb toward 78°F — work tailouts and slow inside bends for rising fish.
- 5 PM - 7 PM: Evening caddis activity picks up in riffles; swing a soft hackle or dead-drift a CDC caddis through the heads of pools before dark.
Guide's Tip
From the benchWith flows at 1,160 CFS and dropping, the Yakima's trout have vacated the shallow bank water and stacked into the deeper mid-channel seams and the soft water behind larger boulders — focus your indicator rigs there, not along the edges. Set your indicator depth to at least 1.5x the water depth and use a longer leader (10-12 ft) off the indicator to keep your nymph in the strike zone longer on each drift. During the midday warmup (noon to 3 PM), keep an eye on flat, slow tailouts for rising fish sipping BWOs and ants — these are the biggest, most selective trout on the river and they're worth the stalk. Approach from downstream, stay low, and make your first cast count.
Main Species
Rainbow Trout
Westslope Cutthroat Trout
Mountain Whitefish
