Llyn Trawsfynydd sits high in Snowdonia — a dramatic, wind-blown upland water surrounded by moorland and crag. It's fished from the bank only (no boats), and the isolation and altitude give it a genuine mountain-water atmosphere. Wild and stocked trout inhabit the water; the scenery is spellbinding. Spring and early summer (April–May) see the best hatches — small olives and early buzzers. The granite moorland setting means soft, slightly acidic water and fast clearing after rain, so lure fishing can be briefly productive after spates. This is a place where you go for the surroundings as much as the sport — the kind of water that teaches you patience and presence.
Good late spring conditions for Llyn Trawsfynydd Reservoir
Good wave on — drift country. Drift fishing weather — three flies on a long leader.
Conditions are not ideal but fishable at Llyn Trawsfynydd Reservoir. The ripple should help fish move and feed more confidently.
66% confidence in this read
Live now
Conditions on the water
Trends shown where the gauge supports them
Wind
W 12 km/h
Gentle breeze
Wave
20 cm ripple
Water temp
—
No reading
Air temp
7°C
Cloud
Broken
Pressure
—
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
Conditions are not ideal but fishable at Llyn Trawsfynydd Reservoir. The ripple should help fish move and feed more confidently.
Where
Start with Buzzer (14-16) on a slow figure-of-eight or hang under indicator. If that does not produce, switch depth or speed before changing the pattern entirely. In the ripple, a bushy searching dry (Hopper, Shipman's, Elk Hair Caddis) outperforms flush emergers — it stays visible and holds the surface tension.
Method
Method not yet authored.
Kit
Kit not yet authored.
Today's tactical plan
The plan
Plan A · Plan B · what to watch · bank or boat
The plan
Plan A
Start with Buzzer (14-16) on a slow figure-of-eight or hang under indicator. If that does not produce, switch depth or speed before changing the pattern entirely. In the ripple, a bushy searching dry (Hopper, Shipman's, Elk Hair Caddis) outperforms flush emergers — it stays visible and holds the surface tension.
Plan B
If fish refuse on top, drop to a buzzer under an indicator at different depths.
Watch for
Keep an eye on changing conditions — wind shifts and cloud breaks can trigger short feeding spells.
Either bank or boat
Good ripple suits both bank and boat. Bank: work inflows, dam walls, and points. Boat: broadside drift covering wind lanes.
Hatches & runs
What's on, when
Twelve months at a glance
Through the year
0–3 scale · May highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
2
1
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Reservoir BuzzerHatch
2
3
3
3
3
3
2
Daphnia SwarmHatch
2
3
3
3
2
Lake OliveHatch
2
3
3
3
3
3
2
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
- Hawthorn Fly is in its seasonal window, boosting the chance of targeted feeding.
Detail · next 12h
Precipitation
The reading most likely to move tomorrow's verdict
About this water · Lough note · 4 min read
Llyn Trawsfynydd Reservoir · profile
Who this water suits
Strengths · watch-outs · best for
About this water
Llyn Trawsfynydd Reservoir, on the water
Field guide · contributor-editedLlyn Trawsfynydd Reservoir · about
What this water is
Background · character · contributors
About this water
Llyn Trawsfynydd sits high in Snowdonia — a dramatic, wind-blown upland water surrounded by moorland and crag. It's fished from the bank only (no boats), and the isolation and altitude give it a genuine mountain-water atmosphere. Wild and stocked trout inhabit the water; the scenery is spellbinding. Spring and early summer (April–May) see the best hatches — small olives and early buzzers. The granite moorland setting means soft, slightly acidic water and fast clearing after rain, so lure fishing can be briefly productive after spates. This is a place where you go for the surroundings as much as the sport — the kind of water that teaches you patience and presence.
- Reservoir
- Granite
Llyn Trawsfynydd Reservoir · directions
How to get to the water
Directions
Llyn Trawsfynydd Reservoir · zones
Where the rules change
Seasons · zones · per-species rules
Seasons & zones
- Trout15 March → 5 October
Llyn Trawsfynydd Reservoir
Google Places
Llyn Trawsfynydd sits high in Snowdonia — a dramatic, wind-blown upland water surrounded by moorland and crag.
Species
Good late spring conditions for Llyn Trawsfynydd Reservoir
Good wave on — drift country. Drift fishing weather — three flies on a long leader.
Conditions are not ideal but fishable at Llyn Trawsfynydd Reservoir. The ripple should help fish move and feed more confidently.
66% confidence in this read
Conditions
Wind
W 12 km/h
Gentle breeze
Wave
20 cm ripple
Water temp
—
No reading
Air temp
7°C
Cloud
Broken
Pressure
—
Rain · 24h
0.0 mm
No rain
Some readings unavailable — check directly before fishing.
Condition match
65%
Cloud70%
Wind65%
Temp60%
A reasonable day here, though temperature isn't quite in the sweet spot.
How to fish it · for brown trout
When
Conditions are not ideal but fishable at Llyn Trawsfynydd Reservoir. The ripple should help fish move and feed more confidently.
Where
Start with Buzzer (14-16) on a slow figure-of-eight or hang under indicator. If that does not produce, switch depth or speed before changing the pattern entirely. In the ripple, a bushy searching dry (Hopper, Shipman's, Elk Hair Caddis) outperforms flush emergers — it stays visible and holds the surface tension.
Method
Method not yet authored.
Kit
Kit not yet authored.
The plan
Plan A
Start with Buzzer (14-16) on a slow figure-of-eight or hang under indicator. If that does not produce, switch depth or speed before changing the pattern entirely. In the ripple, a bushy searching dry (Hopper, Shipman's, Elk Hair Caddis) outperforms flush emergers — it stays visible and holds the surface tension.
Plan B
If fish refuse on top, drop to a buzzer under an indicator at different depths.
Watch for
Keep an eye on changing conditions — wind shifts and cloud breaks can trigger short feeding spells.
Either bank or boat
Good ripple suits both bank and boat. Bank: work inflows, dam walls, and points. Boat: broadside drift covering wind lanes.
Why this score
- Hawthorn Fly is in its seasonal window, boosting the chance of targeted feeding.
Through the year
0–3 scale · May highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
2
1
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Reservoir BuzzerHatch
2
3
3
3
3
3
2
Daphnia SwarmHatch
2
3
3
3
2
Lake OliveHatch
2
3
3
3
3
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Gallery · 1
Terrain map
Directions
About this water
Llyn Trawsfynydd sits high in Snowdonia — a dramatic, wind-blown upland water surrounded by moorland and crag. It's fished from the bank only (no boats), and the isolation and altitude give it a genuine mountain-water atmosphere. Wild and stocked trout inhabit the water; the scenery is spellbinding. Spring and early summer (April–May) see the best hatches — small olives and early buzzers. The granite moorland setting means soft, slightly acidic water and fast clearing after rain, so lure fishing can be briefly productive after spates. This is a place where you go for the surroundings as much as the sport — the kind of water that teaches you patience and presence.
- Reservoir
- Granite
Seasons & zones
- Trout15 March → 5 October
About this water · Lough note · 4 min read
Llyn Trawsfynydd sits high in Snowdonia — a dramatic, wind-blown upland water surrounded by moorland and crag. It's fished from the bank only (no boats), and the isolation and altitude give it a genuine mountain-water atmosphere. Wild and stocked trout inhabit the water; the scenery is spellbinding. Spring and early summer (April–May) see the best hatches — small olives and early buzzers. The granite moorland setting means soft, slightly acidic water and fast clearing after rain, so lure fishing can be briefly productive after spates. This is a place where you go for the surroundings as much as the sport — the kind of water that teaches you patience and presence.
Other water nearby · 5