Island Park Reservoir is the impoundment on the Henrys Fork that feeds the famous river below it, a broad, fertile, weed-rich stillwater up in the Island Park caldera holding rainbows and a few big browns. It's a boat-and-tube fishery, played with leeches, damsels, and chironomids over the weed beds and along the dam face. The fishing swings with the reservoir level and the irrigation draw, and it can get warm and weedy by late summer. Spring and fall, with the caldera rim all around and the big fish on the move, it's a fine, underrated stillwater.
A respectable few hours, if you choose your moments
Good wave on — drift country. A useful wave. Work the productive shore.
45% confidence — limited data
Live now
Conditions on the water
Trends shown where the gauge supports them
Wind
SW 13 km/h
Gentle breeze
Wave
20 cm ripple
Water temp
—
No reading
Air temp
20°C
Cloud
Overcast
Pressure
1013 hPa
Rain · 24h
0.0 mm
No rain
Some readings unavailable — check directly before fishing.
How to fish · for brown trout
The brief
When · where · method · kit
How to fish it · for brown trout
When
No strong hatch signals at the moment — general searching tactics should work best. The ripple is helpful — fish should move onto the feed and a slow-drifted team or single wet will cover water well.
Where
Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point. When no hatch is visible, a buzzer team — black stripped quill on the point, attractor or pearl-rib on the top dropper — is the default starting point on any UK stillwater.
Today's tactical plan
The plan
Plan A · Plan B · what to watch · bank or boat
The plan
Plan A
Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point. When no hatch is visible, a buzzer team — black stripped quill on the point, attractor or pearl-rib on the top dropper — is the default starting point on any UK stillwater.
Plan B
If the main plan is not working, switch to a smaller, more imitative pattern fished slower and deeper. A change of drift angle can also make a difference.
Watch for
Evening tends to be the best period in summer — stay late if you can for a sedge or spinner fall.
Boat — drift
A gentle ripple is ideal for drifting — broadside drift covering the wind lanes should be productive.
Hatches & runs
What's on, when
Twelve months at a glance
Through the year
0–3 scale · June highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Reservoir BuzzerHatch
2
3
3
3
3
3
2
Gray DrakeHatch
2
2
Silverhorns & LonghornsHatch
1
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Today's fly · curated pack
Top pattern + the box
5 patterns from this venue's curated pack
Evidence
Why today scores what it does
The factors driving today's verdict
Why this score
- Temperature (moderate) is in the sweet spot for summer fishing.
About this water · Lough note · 4 min read
Island Park Reservoir · profile
Who this water suits
Strengths · watch-outs · best for
About this water
Island Park Reservoir, on the water
Field guide · contributor-editedIsland Park Reservoir · about
What this water is
Background · character · contributors
About this water
Island Park Reservoir is the impoundment on the Henrys Fork that feeds the famous river below it, a broad, fertile, weed-rich stillwater up in the Island Park caldera holding rainbows and a few big browns. It's a boat-and-tube fishery, played with leeches, damsels, and chironomids over the weed beds and along the dam face. The fishing swings with the reservoir level and the irrigation draw, and it can get warm and weedy by late summer. Spring and fall, with the caldera rim all around and the big fish on the move, it's a fine, underrated stillwater.
- Reservoir
- Mixed
Island Park Reservoir · directions
How to get to the water
Directions
Island Park Reservoir · zones
Where the rules change
Seasons · zones · per-species rules
Seasons & zones
- TroutSaturday of Memorial Day weekend → 30 November
Island Park Reservoir · permits
Good to know
Permits & access
Permit required — see local rules.
- Idaho stillwater regulations — check Idaho Fish & Game
- Level swings with irrigation draw.
Island Park Reservoir
Google Places
Island Park Reservoir is the impoundment on the Henrys Fork that feeds the famous river below it, a broad, fertile, weed-rich stillwater up in the Island Park caldera holding rainbows and a few big browns.
Species
A respectable few hours, if you choose your moments
Good wave on — drift country. A useful wave. Work the productive shore.
45% confidence — limited data
Conditions
Wind
SW 13 km/h
Gentle breeze
Wave
20 cm ripple
Water temp
—
No reading
Air temp
20°C
Cloud
Overcast
Pressure
1013 hPa
Rain · 24h
0.0 mm
No rain
Some readings unavailable — check directly before fishing.
Condition match
77%
Cloud70%
Wind65%
Temp100%
A good match for this venue — most conditions are close to what it fishes best in.
How to fish it · for brown trout
When
No strong hatch signals at the moment — general searching tactics should work best. The ripple is helpful — fish should move onto the feed and a slow-drifted team or single wet will cover water well.
Where
Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point. When no hatch is visible, a buzzer team — black stripped quill on the point, attractor or pearl-rib on the top dropper — is the default starting point on any UK stillwater.
The plan
Plan A
Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point. When no hatch is visible, a buzzer team — black stripped quill on the point, attractor or pearl-rib on the top dropper — is the default starting point on any UK stillwater.
Plan B
If the main plan is not working, switch to a smaller, more imitative pattern fished slower and deeper. A change of drift angle can also make a difference.
Watch for
Evening tends to be the best period in summer — stay late if you can for a sedge or spinner fall.
Boat — drift
A gentle ripple is ideal for drifting — broadside drift covering the wind lanes should be productive.
Why this score
- Temperature (moderate) is in the sweet spot for summer fishing.
Through the year
0–3 scale · June highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Reservoir BuzzerHatch
2
3
3
3
3
3
2
Gray DrakeHatch
2
2
Silverhorns & LonghornsHatch
1
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Gallery · 1
Terrain map
Permits & access
Permit required — see local rules.
- Idaho stillwater regulations — check Idaho Fish & Game
- Level swings with irrigation draw.
Directions
About this water
Island Park Reservoir is the impoundment on the Henrys Fork that feeds the famous river below it, a broad, fertile, weed-rich stillwater up in the Island Park caldera holding rainbows and a few big browns. It's a boat-and-tube fishery, played with leeches, damsels, and chironomids over the weed beds and along the dam face. The fishing swings with the reservoir level and the irrigation draw, and it can get warm and weedy by late summer. Spring and fall, with the caldera rim all around and the big fish on the move, it's a fine, underrated stillwater.
- Reservoir
- Mixed
Seasons & zones
- TroutSaturday of Memorial Day weekend → 30 November
About this water · Lough note · 4 min read
Island Park Reservoir is the impoundment on the Henrys Fork that feeds the famous river below it, a broad, fertile, weed-rich stillwater up in the Island Park caldera holding rainbows and a few big browns. It's a boat-and-tube fishery, played with leeches, damsels, and chironomids over the weed beds and along the dam face. The fishing swings with the reservoir level and the irrigation draw, and it can get warm and weedy by late summer. Spring and fall, with the caldera rim all around and the big fish on the move, it's a fine, underrated stillwater.
Fishing better nearby · 5