Henry's Fork
🎣 Blue-Ribbon Trout
Fremont Co. · 120 mi · Class Riffles–II
929CFS/ 2.91 ft
Optimal→Stable
Optimal: 600–2000 CFS · USGS #13046000
Length
Difficulty
Optimal
Avg Flow
Hist. Median
USGS Gauge
Blue-Ribbon Trout Stream · Harriman State Park
Legendary spring creek voted number one trout stream in America by Trout Unlimited. Henry's Fork of the Snake River is a pilgrimage destination for fly fishers worldwide. The Railroad Ranch section in Harriman State Park is holy water — glassy spring-fed flats where massive rainbow trout sip tiny mayflies in water so clear every refusal is visible.
Trip sections
Big Springs to Island Park Reservoir — 15 mi, spring creek, intimate
Railroad Ranch (Harriman SP) — 6 mi, the holy water, flat and glassy
Last Chance to Ashton — 20 mi, Box Canyon and Mesa Falls, Class II–III
Outfitters
TroutHunter
Henry's Fork fly shop and lodge, Island Park
Henry's Fork Anglers
Island Park-based guides and gear
72-Hour Flow Forecast
NOAA NWPSLoading forecast...
10-Year Flow Patterns
See 10 years of flow patterns for this river — historical analysis is a Pro feature.Upgrade to Pro →
Your Optimal Range
Set your personal optimal CFS window per river — custom ranges are a Pro feature.Upgrade to Pro →
Data Quality
River conditions are community-verified. CFS ranges, difficulty ratings, and trip sections may not reflect every flow level or seasonal change. Always check current conditions, scout unfamiliar rapids, and paddle within your skill level. If you spot an error, use the Improve This River button at the top of the page — your local knowledge is what makes this atlas accurate.