Main Stem Snake River
MAIN STEM SNAKE RIVER
ReportSEP 16 — 23, 2026
🌊
Flow
3250CFS
SNAKE RIVER NR BLACKFOOT ID
🌡️
Water Temp
56.3°F
Updated 2026-09-15
☀️
Weather
47–85°F
Partly Cloudy
🎣
Reported By
Bruce Staples
On the water
Flow below American Falls Dam is running around 5,300 cfs — prime for boating but dangerous for wading — with water temps at 56.3°F and a warm, sunny stretch ahead before a chance of Thursday showers.
From the ShopBruce Staples · September 16, 2026
Holiday crowds of Labor Day Weekend are gone and flow has dropped some as storage in American Falls Reservoir is ramping up. Streamer and woolly bugger patterns on sink tip or full sinking lines with stout leaders remain the best producers.
The snowflake dun (Epeorus) emergence is ongoing in good numbers from the Tilden Bridge area and on downstream. All boat launches above the Tilden Bridge are open.
Flow below American Falls Dam is about 5,300 cfs, so wading there remains dangerous but is ideal for boating.
What's Working — Hot Flies
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Snowflake Dun (Epeorus) | #14–16 | Active — good numbers | Afternoon into evening, Tilden Bridge downstream |
| Baetis / Blue-Winged Olive | #18–22 | Seasonal — watch for overcast windows | Midday to afternoon |
| Caddis | #16–18 | Seasonal — sporadic | Evening |
Best Time Window
- EARLY MORNING TO MIDDAY: Run streamers and woolly bugger patterns on sinking lines — fish are actively chasing baitfish in the big flows
- AFTERNOON INTO EVENING: Watch for the snowflake dun (Epeorus) emergence from Tilden Bridge downstream and be ready to switch to a dry fly presentation
- WEDNESDAY ALL DAY: Sunny skies and temps near 85°F make for a full day on the water — streamer bite should hold strong before Thursday's storm chance arrives
Guide's Tip
From the benchRig a full sinking or sink tip line with a stout leader before you launch — that's the setup Madison says is producing, and at 5,300 cfs below the dam you won't have time to swap mid-float. For the snowflake dun rise, a dedicated Epeorus or Snowflake Dun dry fly pattern is the ideal match; if you tie your own, bring a few size 14–16 comparaduns or sparkle duns in pale yellow-olive. All boat launches above Tilden Bridge are open, so plan your put-in accordingly and leave the wading gear at home below the dam.
Main Species
Brown Trout
Rainbow Trout
Yellowstone Cutthroat Trout
