Yesterday's cool temperatures and afternoon showers kept water quality excellent across all reaches. Most river temps stayed in the 50s all day — the coolest since May 21. Reservoir at 89%, drafting steadily as natural flow declines.
Reported by Rob Van Kirk · HFF Science & Technology
💧
Outflow
761cfs
↑ UP FROM 595 CFS
❄️
SWE
7%
↓ 2ND LOWEST ON RECORD
🏞️
Reservoir
89%
↓ BELOW AVG 98%
🌡️
Temp Δ
-11°F
↓ COOLEST SINCE MAY 21
01
▸ The Water · 3-Day Window
Reach by reach.
Real-time water quality, temperature, and clarity from the Henry's Fork Foundation sonde network and watershed science — supplemented by USGS flow gauges and NOAA forecasts. Tap any reach for the full dashboard.
Reach data sponsored by
Box Canyon
Island Park Dam Outflow · Henry's Fork, ID
Trout Comfort
Fish any time
Flow
761
CFS
Water Temp
52
°F
Clarity
Clear
Turbidity
1.5
NTU
Below average · algae growth cycle muted by wind mixing
Last Chance
Last Chance to Pinehaven · Henry's Fork, ID
Trout Comfort
Fish any time
Flow
820
CFS
Water Temp
57
°F
Clarity
Slightly off-color
Turbidity
3.5
NTU
Continuing slow decrease · below average for date
Warm River → Ashton
Fall River confluence · Henry's Fork, ID
Trout Comfort
Fish any time
Flow
1600
CFS
Water Temp
58
°F
Clarity
Slightly off-color
Turbidity
4.0
NTU
Fall River contribution stable · below average for date
Chester → St. Anthony
Lower Henry's Fork · below all diversions
Trout Comfort
Fish any time
Flow
480
CFS
Water Temp
59
°F
Clarity
Slightly off-color
Turbidity
4.5
NTU
Elevated from irrigation return flows · stable
🌡️
Trout thermal zones:
Optimal:below 65°
Stressful:65–68°
Harmful:above 68°
HFF voluntary closures protect trout during thermal stress
02
▸ The Bugs · Right Now
What’s on the wing.
A guide to the insects active across the Henry’s Fork — and the ones about to be.
— THE HATCH BOARD —
06 · 11 · 2026 · ALL REACHES · NORMAL vs HFF THERMAL MODEL
HEADWATERS PARTNER ·
🪶
Pale Morning Duns
Ephemerella spp.
Peak emergence. Best fishing in Last Chance and Box Canyon.
Normal Window
Jun 15 – Jul 15
long-term average
Predicted 2026
May 20 – Jun 20
~25 days early
HIGH
#16–18
🪶
Green Drakes
Drunella grandis
Active in Box Canyon. Watch for spinner falls in evening.
Normal Window
Jun 20 – Jul 10
long-term average
Predicted 2026
Jun 1 – Jun 20
~19 days early
HIGH
#10–12
🪶
Brown Drakes
Ephemera simulans
Triggered by warm evenings. Evening emergence Last Chance.
Normal Window
Jun 20 – Jul 5
long-term average
Predicted 2026
Jun 5 – Jun 20
~15 days early
BUILDING
#10–12
🪶
Yellow Sallies
Isoperla spp.
Active in riffles from Warm River downstream.
Normal Window
Jun 1 – Jul 15
long-term average
Predicted 2026
May 15 – Jun 30
~17 days early
HIGH
#14–16
🪶
Caddis (Mother's Day)
Brachycentrus occidentalis
Winding down. Egg-laying flights still active evenings.
Normal Window
May 5 – May 25
long-term average
Predicted 2026
Apr 15 – May 10
~20 days early
MODERATE
#14–16
⚡ HFF THERMAL MODEL
Bugs are emerging weeks ahead of schedule.
MAX
25
DAYS EARLY
MEAN
19
DAYS EARLY
MIN
15
DAYS EARLY
“
Water quality was good to excellent again yesterday due to cool temperatures and afternoon clouds. Water temperatures barely hit 60 degrees yesterday, as most river reaches stayed in the 50s all day.
— — Rob Van Kirk · June 11, 2026
★ FOR THE RIVER
You read this report. Now stand behind it.
Every data point on this page exists because of HFF members. Join 3,000+ anglers who fund the science that keeps this river alive.
Every input that drives the Henry’s Fork — snowpack, storage, diversion, and the subwatersheds feeding the system.
№ 01
🏞️
IP Reservoir
89%
Dropped 671 ac-ft · avg 98% for date
№ 02
🚰
Diversion
104%
of average · steady
№ 03
🌧️
WY Precip
90%
of average · afternoon showers helping
№ 04
💧
SWE
7%
of peak · 2nd lowest on record
№ 05
🌡️
Temp Δ
−11°F
Coolest day since May 21
№ 06
📊
Natural Flow
54%
of average · declining in all subwatersheds
Natural Flow · % of average
Upper HF
54%
Teton
54%
Fall River
54%
IP Dam Outflow · 14 days · USGS daily mean
04
▸ Today’s Charts · HFF Watershed
The science, plotted.
Six watershed charts straight from Rob Van Kirk’s daily water report. Mean temperature, precipitation, snow water equivalent, natural flow, diversion, and supply vs. demand — all year-to-date against the 38-year record.
Watershed Mean Temperature
Water year to date vs. 1989–2025 average
Watershed Precipitation
Accumulated, water year to date
Watershed SWE Accumulation
Snow water equivalent vs. record
Total Natural Flow
Henry’s Fork water supply
Watershed Total Diversion
Combined HF, Fall, Teton
Supply minus Demand
Indicator for Island Park draft
Charts produced by Henry’s Fork Foundation Science & Technology · Updated daily with Rob Van Kirk’s water report
05
▸ The Index · Live Dashboards
Go to the source.
Twelve direct links into Rob Van Kirk’s daily water report and HFF data apps for interactive, real-time data.
▸ ON-THE-WATER INTEL
Meet our River Ambassadors.
For the best knowledge of the fishing, contact one of our River Ambassadors — the guides and fly shops who live this river every day.
