Spate · Slate · North Wales / Gwynedd / Eryri

Ogwen

The Ogwen river flowing from Llyn Ogwen with the peak of Tryfan rising behind it.
Contributor photo

Afon Ogwen just after leaving Llyn Ogwen, with Tryfan in the background, Snowdonia.

John Fielding, CC BY-SA 2.0

Short Eryri river — under seven miles from Llyn Ogwen above Bethesda to the Menai Strait at Aber.

Poor · Atlantic Salmon
Poorlive now
Slow going — better windows ahead
River lifting fast on the rain. Little in your favour today. Fish the certain lies, or leave it for a better one.
90% confidence
What moved it
  • LevelProxyvia Seiont
  • Water temp21.4°C
  • ClarityVery colouredColouring up
Conditions on the water
Proxy gauge
Level
Rising
Proxy
via Seiont
Water temp21.4°C
ClarityVery coloured
Weather22°C
WindSW 10 km/h
Pressure1019 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

No gauge on this water — conditions are inferred from Seiont. The trend transfers, the absolute level does not.

Water temperature for atlantic salmon
Warm — slow
21°C est.ideal 10–14°C
0°14°28°
How to fish it · for atlantic salmon
When
Summer through autumn. Fish on the drop after rain — 6 to 12 hours into a falling spate. Grilse from July.
Where
Lower Ogwen pools through the slate-walled stretches above the tidal limit at Aber.
Method
Small doubles 10 to 12 across-and-down on a floating line; small tubes on a sink-tip in spring or coloured water. Fish the named lies in each pool, working systematically before moving on. Mandatory catch-and-release under NRW byelaw — every salmon goes back.
Kit
10 ft #7/8 single-hander or 11 ft switch — small spate scale; double-handers are wasted on these rivers. Floating line plus light sink-tip. 10 to 12 lb fluoro tippet.
Why this works
⛔ Water at 21.4°C. This is the line where catch-and-release kills atlantic salmon. Do not fish for them today.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 3 active hatches hour by hour with Pro.

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Evidence
Survey-backed · regionalModerate confidence

Backed by regional invertebrate surveys; no sampling on this exact reach yet.

Through the year
0–3 scale · July highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Salmon runRun
1
2
2
2
2
2
1
Sea trout runRun
1
2
2
2
2
2
2
1
Trout seasonSeason
1
2
2
2
2
2
1
Daddy Long LegsHatch
2
3
2
March BrownHatch
2
3
2
GrannomHatch
2
2
Large StoneflyHatch
2
3
2

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

Beats · 1
Ogwen Valley AA — day ticket via Fishing PassportAccess varies
The Ogwen begins at Llyn Ogwen and falls rapidly through the Ogwen Falls into a string of small pools that hold wild brown trout only — the upper section is too steep and broken for migratory fish.
What's coming
Plan ahead
5-day outlook
Cooler water nearby · 1
Probably above the atlantic salmon safety line — these are likely cooler, but carry a thermometer.
Dwyfor / Dwyfach
30 km
~18°C
Brown trout · Salmon · Sea trout
Gallery · 2
  1. The Ogwen river flowing from Llyn Ogwen with the peak of Tryfan rising behind it.
    Afon Ogwen just after leaving Llyn Ogwen, with Tryfan in the background, Snowdonia.
  2. Terrain map of the venue
    Terrain map
About this water

Short Eryri river — under seven miles from Llyn Ogwen above Bethesda to the Menai Strait at Aber. Ogwen Valley AA reports consistent sea trout and a creditable salmon and grilse run for a river so small. Slate-walled pools, quick rise and quicker drop, and a fishery of much more interest than the size suggests. Atlantic salmon are under serious conservation pressure — Natural Resources Wales mandates catch-and-release for salmon on all rivers, so all fish must be returned.

Under the surface

Afon Ogwen drains some of the greatest peaks in Eryri — the Glyderau and Carneddau crowd its head — gathering in Llyn Ogwen from three mountain streams before tipping over the cataracts of Rhaeadr Ogwen and down the glacier-carved trough of Nant Ffrancon. It is a short river, barely seven miles, but a steep and dramatic one, falling fast from lake to sea on the eastern edge of Bangor past the vast slate tips of the Penrhyn quarry. The water is clear, cold and acidic off the high ground, carried over hard rock and boulder through a classic U-shaped glaciated valley. Despite its size it holds a good run of sea trout and a strong run of salmon and grilse, with wild brown trout above. The character is true spate water, quick to rise and fall. Wading is boulder work on uneven, slippery rock, and the falls and steep reaches ask for a careful foot.

Wading: Slippery boulders and steep cataracts

  • Slate
  • Partly confined
  • Step pool
  • Pool riffle
Why this score · for atlantic salmon
  • Temperature130% weight
  • Flow6025% weight
  • Clarity1520% weight
  • Feeding Time5015% weight
  • Pressure8510% weight
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Salmon1 April → 17 October
  • Sea trout3 March → 17 October
  • Trout3 March → 30 September

Sea trout: Variable seasonal (2026) — Short Eryri spate with consistent reported sewin from the local association. Fast response means the windows are brief; All-Wales At Risk picture applies.

Related guides
Atlantic Salmonsalmon tacticsYorkshire & SpidersNorth Country methodsEuro Nymphingsubsurface methods
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