Stillwater · Slate · Denbighshire / Hiraethog moors

Llyn Brenig

Broad landscape view across Llyn Brenig reservoir on a clear day, moorland hills reflected in calm open water.
Fair · Rainbow
Olive Damsel · 10-12
Fairlive now
Good summer conditions for Llyn Brenig
Water temperature is the limiting factor today, not the wave. Fish dawn or dusk if you go at all, and handle everything with extra care.
61% confidence
What moved it
  • WindSW 10 km/hLight breeze
Today's fly
OD
Olive Damsel10-12
Retrieve, sub-surface
Conditions on the water
Live gauge
Wind
Light breeze
SW 10 km/h
N
SW
from the south-west
WaveRipple
Water temp—
Air temp27°C
CloudBroken
Pressure1020 hPa
Rain · recent0.0 mm

Some readings unavailable — check directly before fishing.

How to fish it · for Rainbow
When
Cold-water upland — buzzers come on later than the southern reservoirs, May through July. Sedges into September; back-end lures before October close. Wait for the air to warm.
Where
Open water boat marks; the dam end and the eastern bays. Brenig's altitude means weather drives the fishing more than season alone.
Method
Floater with buzzers under indicator in late spring; midge-tip with team of three through summer; lures on intermediate when fish are deep.
Kit
10 ft #7 boat rod; floating, intermediate and fast-intermediate lines; 6 to 8 lb fluoro. Drogue and a long-handled net.
The plan
Plan A

Start with Diawl Bach (12-14) — on the bob / top dropper — slow figure-of-eight retrieve. 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

Fish early and late, try deeper during the heat of the day with a fast-sinking line.

Watch for

Buzzers may strengthen through the middle of the day as conditions warm.

Either bank or boat

Good ripple suits both bank and boat. Bank: work inflows, dam walls, and points. Boat: broadside drift covering wind lanes.

Sub-surface · on the nymphunder the surface

Hatch predictions

See the full sub-surface read with Pro.

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 3 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
Trout seasonSeason
1
2
2
2
2
2
2
1
Daphnia SwarmHatch
2
3
3
3
2
Daddy Long LegsHatch
2
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
What's coming
Plan ahead
5-day outlook
Condition match
88%
Cloud100%
Wind100%
Temp60%

Conditions are ideal for Llyn Brenig — wind, cloud and temperature all line up.

Other water nearby · 5
Alwen Reservoir
3.0 km
Brown trout · Rainbow trout
Llyn Clywedog (Saron)
4.0 km
Brown trout
Tyn Y Fron Fishing
18 km
Rainbow trout · Brown trout
Tan-y-Mynydd Trout Fishery
19 km
Rainbow trout · Brown trout
Llyn Elsi
19 km
Brown trout
Gallery · 6
  1. Broad landscape view across Llyn Brenig reservoir on a clear day, moorland hills reflected in calm open water.
    Llyn Brenig Reservoir
  2. Upland reservoir landscape at Llyn Brenig showing open water amid moorland under a wide sky.
    Llyn Brenig
  3. Wide panoramic view of Llyn Brenig reservoir showing the full breadth of open water under a cloudy sky.
    Llyn Brenig from the western shore
  4. Golden sunrise light over the open water of Llyn Brenig reservoir, North Wales.
    Sunrise over Llyn Brenig
  5. Fishing boats moored on the shore of Llyn Brenig reservoir with open water and moorland hills behind.
    Boats on Llyn Brenig
  6. Terrain map of the venue
    Terrain map
Water quality (WFD)
  • Ecology: Moderate
  • Chemical: Unknown
What this classification means

NRW WFD Cycle 3 (lake) — Llyn Brenig: Moderate ecological status. Re-tagged 2026-06-18 from a feeder-river reach to the reservoir's own lake waterbody. Source: NRW DataMapWales WFD Cycle 3 classification layer.

NRW (Wales) · GB31133923

Why this score
  • Wind conditions (ripple) closely match what this water fishes best in.
  • Cloud cover (mixed) suits the fishery well.
  • Buzzers are in their seasonal window, boosting the chance of targeted feeding.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 26 March → 15 October
Related guides
Big Stillwater Playbookreservoir tacticsReservoir Entomologymatching the hatchThermal Layers & Troutreading depth and temperature
Casting instructors near here
Booking & contacts
Clubs & associations