Stillwater · Slate · Denbighshire / Hiraethog moors, GB-WLS

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
Evening session looks promising at Llyn Brenig
Good wave on — drift country. A useful wave. Work the productive shore.
61% confidence
What moved it
  • WindN 14 km/hGentle breeze
Today's fly
Olive Damsel
Olive Damsel10-12
Retrieve, sub-surface
Conditions on the water
Live gauge
Wind
Gentle breeze
N 14 km/h
N
N
from the north
Wave20 cm ripple
Water temp—
Air temp15°C
CloudClear
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 Olive Damsel (10-12) — on the point. 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 surface work dries up, try a diawl bach or hare's ear on the point and skate a sedge pattern on the bob at last light.

Watch for

Evening tends to be the best period in summer — stay late if you can for a sedge or spinner fall.

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

Top nymph shown — see all 3 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
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
65%
Cloud70%
Wind65%
Temp60%

A reasonable day here, though temperature isn't quite in the sweet spot.

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
  • Sedge is in its seasonal window, boosting the chance of targeted feeding.
Directions
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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