Still Waters
STILL WATERS
ReportOCT 21 — 28, 2026
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Flow
—CFS
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Water Temp
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Weather
32–63°F
Mostly Clear
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Reported By
Bruce Staples
On the water
Cooling October temperatures are clearing blue-green algae from southern Idaho irrigation reservoirs, opening the door for improving fly fishing. Midge pupa fished at the right depth is the primary tactic right now.
From the ShopBruce Staples · October 21, 2026
Fishing on irrigation reservoirs is improving because of cooling waters and the retreat of blue-green algae mats. These not only hinder fly presentation, but interfere with aquatic insect growth.
On still waters without algae mats, midge pupa will be the primary pattern for success — the key is finding the taking depth. The recent heavy rainfall may have put some remote roads into four-wheel drive condition; check with County Road and Bridge websites before heading out.
Fish salvage regulations are being applied to a few southern Idaho irrigation reservoirs that have been drained down to the extreme.
What's Working — Hot Flies
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Midge (Chironomid) — Pupa | #16–22 | All day; peaks midday as water warms | 10 AM – 3 PM |
| Midge (Chironomid) — Adult | #18–22 | Light surface activity on calm, warmer afternoons | 12 PM – 2 PM |
| Midge (Chironomid) — Larva | #16–20 | Sub-surface; fish deep near bottom early in the day | 8 AM – 11 AM |
Best Time Window
- 10 AM – 2 PM: Prime midge pupa window as air temps climb toward the low 60s and surface activity picks up — focus on finding the taking depth with a suspended pupa rig.
- 2 PM – DARK: Slower but fish remain active sub-surface; slow-strip or dead-drift a balanced leech or midge pupa combo as light fades and temperatures begin to drop.
Guide's Tip
From the benchThe single most important variable on these reservoirs right now is depth — midge pupa need to be presented at the exact level fish are holding, which can change throughout the day. Start shallow and work deeper in measured increments until you find the taking zone, then stay there. Before driving to any remote reservoir, check your county's Road and Bridge website; recent heavy rains may have left access roads in four-wheel drive condition. Also note that a handful of southern Idaho irrigation reservoirs are currently under fish salvage regulations due to extreme drawdowns — confirm your destination's status before you go.
Main Species
Rainbow Trout
Brook Trout
Yellowstone Cutthroat Trout
