Main Stem Snake River
MAIN STEM SNAKE RIVER
ReportJUL 30 — AUG 6, 2026
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Flow
5160CFS
SNAKE RIVER NR BLACKFOOT ID
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Water Temp
56.3°F
Updated 2026-07-30
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Weather
61–101°F
Sunny then Isolated Showers And Thunderstorms
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Reported By
Bruce Staples
On the water
Spring inflows from the Fort Hall Reservation are keeping the upper reach (Tilden Bridge to the reservoir) cool at 56.3°F, with flows around 4,250 cfs — prime boating water. Below American Falls Dam, flows are running near 10,000 cfs; wading is dangerous and all fishing should be done from a boat.
From the ShopMadison Losee · July 30, 2026
The best fly fishing above the reservoir is from Tilden Bridge down to the reservoir because of cool inflow from numerous springs mostly coming in from the Fort Hall Reservation. Flow here is about 4,250 cfs. Boating is the safest and most effective way to fish. Streamer and woolly bugger patterns on sink tip or full sinking lines with stout leaders are the best producers under these conditions. All boat launch ramps are open.
Flow below American Falls Dam is about 10,000 cfs, so wading there is dangerous. This flow is ideal for boating and makes all launch sites easily accessible.
What's Working — Hot Flies
Hatch Chart
| Insect | Size | Activity | Prime Time |
|---|---|---|---|
| Baitfish / Sculpin | #4–6 | All day | Morning and overcast periods |
| Crayfish | #6 | Active | Morning through midday |
| Leeches | #8–14 | Moderate | Low-light hours |
Best Time Window
- EARLY MORNING (6–10 AM): Coolest air temps and low light — prime time to swing streamers and buggers through the spring seams from Tilden Bridge down to the reservoir.
- MIDDAY (10 AM–2 PM): Fish deeper runs and slots with full sinking lines as the sun climbs; below American Falls Dam, focus boat positioning on current edges at 10,000 cfs.
- AVOID AFTER 3 PM: Isolated thunderstorms possible both today and Friday afternoon — get off the water before storms develop in this exposed river corridor.
Guide's Tip
From the benchTraditional woolly buggers (not currently in the online catalog) are specifically called out by Madison as top producers — pick some up in-store or tie your own in olive and black before heading out. Rig a stout leader of 0X–2X on your sink-tip or full sinking line to turn over these heavier patterns and handle the fish that live in this kind of water. With highs near 96–101°F this week and afternoon thunderstorms possible after 3 PM, plan to be on the water early and off before the heat and storms build.
Main Species
Brown Trout
Rainbow Trout
Yellowstone Cutthroat Trout
