Main Stem Snake River
MAIN STEM SNAKE RIVER
ReportSEP 1 — 8, 2026
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Flow
4450CFS
SNAKE RIVER NR BLACKFOOT ID
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Water Temp
56.3°F
Updated 2026-09-01
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Weather
49–84°F
Isolated Showers And Thunderstorms
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Reported By
Bruce Staples
On the water
Flow at the Blackfoot gauge is 4,450 cfs and water temperature is 56.3°F — ideal boating conditions with all launch sites above Tilden Bridge open and accessible. Flow below American Falls Dam is running around 8,600 cfs, making wading in that stretch dangerous.
From the ShopBruce Staples · September 1, 2026
Through this week and into the following weekdays will be the best time to beat the holiday crowds on Labor Day Weekend. The number of motorized recreationists on the river those three days will make fishing less tranquil.
Streamer and woolly bugger patterns on sink tip or full sinking lines with stout leaders remain the best producers. There is a snowflake dun (Epeorus) ongoing in good numbers during cloudy conditions on slower waters from the Tilden Bridge area and on downstream.
All boat launches above the Tilden Bridge are open. Flow below American Falls Dam is about 8,600 cfs, so wading there is dangerous. This flow is ideal for boating and makes all launch sites easily used.
What's Working — Hot Flies
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Snowflake Dun (Epeorus) | #14–16 | Good numbers during cloudy conditions | Midday–Afternoon on overcast days |
| Caddis | #16–18 | Moderate — typical late-summer presence | Evening |
| Terrestrials (Ants, Hoppers) | #10–16 | Opportunistic — warm September afternoons | Midday–Afternoon |
Best Time Window
- TUESDAY SEPT 1 THROUGH FRIDAY SEPT 5 (WEEKDAYS): Fish now and after the holiday to avoid heavy motorized boat traffic — Labor Day Weekend will be crowded on the water
- CLOUDY AFTERNOON WINDOWS: Target slower water from Tilden Bridge downstream for the Epeorus snowflake dun hatch — overcast skies trigger the best activity
- FULL DAY FROM A BOAT: All launches above Tilden Bridge are open and the 4,450 cfs flow at Blackfoot makes every site easily accessible — ideal conditions for a float
Guide's Tip
From the benchThe snowflake dun (Epeorus) hatch is a pale, delicate mayfly — watch for rising fish in the slower, flatter water from Tilden Bridge downstream whenever clouds roll in, which looks likely this afternoon and again Wednesday night per the forecast. No exact snowflake dun dry fly is in our current catalog, so ask us at the shop for our closest Epeorus imitation. Pair a stout leader with your sink tip or full sinking line for streamers — the current is pushing hard and light tippet will cost you fish.
Main Species
Brown Trout
Rainbow Trout
Yellowstone Cutthroat Trout
