Stillwater · Mixed · Anglesey, North Wales

Llyn Alaw

Shoreline view across the still open water of Llyn Alaw reservoir on Anglesey, with reeds and a bankside bush in the foreground and low hills on the far shore.

Anglesey's largest lake — a reservoir built in 1965-66 by flooding Cors y Bol bog, historically run by Welsh Water as a well-regarded rainbow and wild brown trout fishery.

Fair · Rainbow
Coch-y-Bonddu Beetle · 10-14
A respectable few hours, if you choose your moments
Useful ripple, fishable wave. Worth a session if the wind holds.
49% confidence
limited data

Llyn Alaw is often best in spring through autumn.

What moved it
  • WindN 27 km/hModerate breeze
Today's fly
Coch-y-Bonddu Beetle
Coch-y-Bonddu Beetle10-14
Upstream dry, on top
Conditions on the water
Estimate
Wind
Moderate breeze
N 27 km/h
N
N
from the north
Wave60 cm wave
Water temp—
Air temp14°C
CloudClear
Pressure1022 hPa
Rain · recent0.0 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

How to fish it · for Rainbow
When
Conditions are not ideal but fishable at Llyn Alaw. Early morning is often the most productive window in summer — make the most of it.
Where
Start with Daddy Long Legs (10-12) on a As per local method. Evening can produce explosive surface takes — try a foam beetle or booby on a long leader. Rainbows respond to more active retrieves — try short strips between pauses.
The plan
Plan A

Start with Daddy Long Legs (10-12) on a As per local method. Evening can produce explosive surface takes — try a foam beetle or booby on a long leader. Rainbows respond to more active retrieves — try short strips between pauses.

Plan B

If the daddy is being refused, drop to a hopper or a single foam beetle and cover rising fish individually.

Watch for

Sedge should come on through the afternoon as the water warms.

Bank

Bank-only venue. Fish from accessible margins, points, weed edges, and inflows.

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 4 guilds with Pro.

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 5 with Pro.

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Through the year
0–3 scale · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
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
Silverhorns & LonghornsHatch
1
2
2
2
1

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Rainbow fly box

Traditional wild-trout llyn fishing. Wet flies and dabblers stay central, with buzzer, caddis, terrestrials and occasional small fry patterns becoming important as the season warms.

Bays & launches · 1

No confirmed current fishery operator. Contact Dŵr Cymru Welsh Water's North Wales reservoirs office before planning a trip.

Fishery status — currently closedMembers-only
Welsh Water suspended fishing here around 2012-13 pending a management retender that appears never to have concluded.
Visit official site ↗
What's coming
Plan ahead
5-day outlook
Condition match
38%
Cloud25%
Wind30%
Temp60%

Conditions are away from Llyn Alaw's sweet spot — it usually fishes best in ripple wind with cloud skies.

Other water nearby · 5
Llyn Cefni Reservoir
10 km
Brown trout · Rainbow trout
Llyn Coron
17 km
Brown trout · Rainbow trout
Llyn Padarn
32 km
Brown trout · Arctic char
Llyn Cwm Dwythwch
34 km
Brown trout
Llyn Cwellyn
36 km
Brown trout · Arctic char · Salmon
Gallery · 2
  1. Shoreline view across the still open water of Llyn Alaw reservoir on Anglesey, with reeds and a bankside bush in the foreground and low hills on the far shore.
    Southern end of Llyn Alaw Reservoir
  2. Terrain map of the venue
    Terrain map
About this water

Anglesey's largest lake — a reservoir built in 1965-66 by flooding Cors y Bol bog, historically run by Welsh Water as a well-regarded rainbow and wild brown trout fishery. Important honesty note: the fishery has been closed to public angling since around 2012-13, pending a management tender that never visibly concluded — Welsh Water's current list of reservoirs open for fishing (Brenig, Alwen, Aled and Cowlyd, the Elan valley, Llys-y-fran, Llandegfedd, and several South Wales reservoirs) does not include Alaw. Older day-ticket pricing and contact details still circulate on directory sites, but they predate the closure and shouldn't be trusted. The lake is now primarily a bird reserve (SSSI, notified for over-wintering whooper swan, shoveler and teal), which is likely part of why angling hasn't resumed.

  • Reservoir
  • Mixed
Why this score
  • Wind conditions (windy) are not ideal for this water.
  • Daddy Longlegs are in their seasonal window, boosting the chance of targeted feeding.
Related guides
Big Stillwater Playbookreservoir tacticsReservoir Entomologymatching the hatchThermal Layers & Troutreading depth and temperature
Casting instructors near here
Booking & contacts