Stillwater · Ordovician Volcanics · Wales / Snowdonia (Blaenau Ffestiniog uplands), GB-WLS

Llyn Cwm Corsiog

Calm upland lake (Llyn Cwm Corsiog) surrounded by rocky, grassy banks with misty hills in the background, Snowdonia.

Corsiog is the smallest, shallowest thing in the Cambrian AA book, and it fishes like it — a modest pool of peat-stained water tucked in below Conglog that colours quickly in wind and clears just as fast.

Fair · Trout
Minkie · 6-10
Fairlive now
Buzzer expected on Llyn Cwm Corsiog
Good wave on — drift country. A useful wave. Work the productive shore.
60% confidence

Llyn Cwm Corsiog is often best in spring through autumn.

What moved it
  • WindW 9 km/hLight breeze · Gusts to 18 km/h
Today's fly
Minkie
Minkie6-10
Retrieve, sub-surface
Conditions on the water
Estimate
Wind
Light breeze · Gusts to 18 km/h
W 9 km/h
N
W
from the west
WaveRipple
Water temp9.5°C
Air temp13°C
CloudOvercast
Pressure1017 hPa
Rain · recent0.0 mm

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

Head to
Wind driftSW wind
North-eastern end

A southwesterly has held for the best part of three days, running warmer than the water (12°C air against 10°C water). Expect fish at the north-eastern end — the bank it is blowing into — where the drift piles food, colour and warmth together. This reads the upper water, though — a bottom bait at range feels it far less than a floater or a fish in the margins. Treat it as a tiebreaker between good swims rather than an override — features and angling pressure usually count for more.

How to fish it · for Trout
When
June–August; best on overcast, breezy days
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.
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.

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

Watch for Sedge towards evening — this could be the best window of the day.

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 2 guilds as a supporter.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 5 as a supporter.

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Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Heather FlyHatch
2
2
Daddy Long LegsHatch
2
3
2
Claret DunHatch
2
3
2
Murrough (Great Red Sedge)Hatch
2
3
2

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

Ranked for today
Trout fly box
Bays & launches · 1
Day ticket via Cambrian Angling AssociationAccess varies
Very small, shallow moorland pool near Llyn Conglog; covered by the Cambrian AA's single day ticket across the whole llyn portfolio.
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What's coming
Plan ahead
5-day outlook
Condition match
73%
Cloud50%
Wind100%
Temp60%

A good match for Llyn Cwm Corsiog — most conditions are close to what it fishes best in.

Other water nearby · 5
Gallery · 2
  1. Calm upland lake (Llyn Cwm Corsiog) surrounded by rocky, grassy banks with misty hills in the background, Snowdonia.
    Llyn Cwm Corsiog
  2. Terrain map of the venue
    Terrain map
About this water

Corsiog is the smallest, shallowest thing in the Cambrian AA book, and it fishes like it — a modest pool of peat-stained water tucked in below Conglog that colours quickly in wind and clears just as fast. Don't come expecting size; come expecting the particular pleasure of fishing water nobody else bothers with. The wild brown trout here are small and willing rather than selective, which suits a short evening session when you've already walked further than planned to reach the bigger neighbours. Treat it as a bonus stop on a longer day in this corner of the uplands, not a destination in its own right.

  • Lake
  • Ordovician volcanics
Why this score
  • Wind conditions (ripple) closely match what this water fishes best in.
  • Buzzer is in its seasonal window, boosting the chance of targeted feeding.
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