Spate · Limestone Karst · North East Wales (Alyn Valley, Dee tributary)

Alyn

The River Alyn flowing through autumn woodland near Rhydymwyn, North Wales.
Contributor photo

Autumn, River Alyn, Rhydymwyn area

Phil Corless - Public Domain

The Alyn rises on Llandegla Moors and crosses a carboniferous-limestone gorge at Loggerheads that genuinely swallows it — between Loggerheads and Rhydymwyn the river can run dry into natural swallow holes in low rainfall, worsened by the Milwr Tunnel, a Victorian lead-mine drainage tunnel that still permanently diverts around 23 million gallons a day out of the catchment to the Dee Estuary.

Poor · Brown Trout
Coch-y-Bonddu Beetle · 10-14
Poorlive now
Not the day for it
River temperature is the limiting factor today, not the flow. This is not the day to push it. Check the thermal advice above before you head out.
80% confidence
What moved it
  • LevelDry recentlyNo gauge reading
  • Water temp21.5°C
  • ClarityClear
Today’s fly
CY
Coch-y-Bonddu Beetle10-14
Upstream dry, on top
Conditions on the water
Estimate
Level
Dry recently
No gauge reading
Water temp21.5°C
ClarityClear
Weather28°C
WindE 8 km/h
Pressure1020 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

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

Water temperature for brown trout
Warm — slow
22°C est.ideal 10–16°C
0°14°28°
How to fish it · for brown trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Why this works
⚠️ Water at 21.5°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots. Otherwise very poor — water clarity is in the right range.
Hatch timeline · todayPeak at 12pm

Hatch predictions

Today's headline hatch shown — see all 12 active hatches hour by hour with Pro.

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Through the year
0–3 scale · July highlighted
J
F
M
A
M
J
J
A
S
O
N
D
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.

Ranked for today
Brown Trout fly box
Beats · 3 · 1 reaches

Day-ticket access concentrates on the lower-middle river around Rossett and Wrexham (Rossett & Gresford Flyfishers, Bradley AC). Warrington AA's water is members-only.

Alyn day-ticket water · 3 beatsMixed
Rossett & Gresford Flyfishers, Bradley Angling Club, Warrington AA — Ithell's Farm
The 3 beats
Rossett & Gresford FlyfishersDay tickets
Rossett & Gresford Flyfishers (day ticket via Fishing Passport)
2.5 miles from the railway bridge at Rossett upstream to Wormswood, Gresford — founded 1906, one of the oldest continuously-running clubs in Wales. Wild brown trout throughout; grayling established here since 2008 and now breeding. Migratory salmon and sea trout are seen scaling Rossett weir most years but rarely dwell — not a targetable run.
Day ticket £20/rod (2026 pricing). Fly-only, barbless hooks, no dogs, wash-off biosecurity policy applies.
Bradley Angling ClubDay tickets
Bradley Angling Club
From the Llay new road, Wrexham, upstream to Llay Hall Industrial Estate — mid-lower river, downstream of the Rossett & Gresford water.
Season 3 Mar–30 Sep. New adult £30, junior/senior £20 (2026 prices). Bag limit 2/day. Worm or fly only — no maggots or spinners.
Warrington AA — Ithell's FarmMembers
Warrington Anglers Association
Ithell's Farm stretch near Rossett, plus a second stretch elsewhere on the river — a large Cheshire-based club that also holds water on the Severn and Vyrnwy.
Members only, open membership policy — no day tickets sold.
What's coming
Plan ahead
5-day outlook
Water here around 22°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. The River Alyn flowing through autumn woodland near Rhydymwyn, North Wales.
    Autumn, River Alyn, Rhydymwyn area
  2. Terrain map of the venue
    Terrain map
About this water

The Alyn rises on Llandegla Moors and crosses a carboniferous-limestone gorge at Loggerheads that genuinely swallows it — between Loggerheads and Rhydymwyn the river can run dry into natural swallow holes in low rainfall, worsened by the Milwr Tunnel, a Victorian lead-mine drainage tunnel that still permanently diverts around 23 million gallons a day out of the catchment to the Dee Estuary. Above and below that dry section it's real wild brown trout and grayling water — alkaline, gin-clear over gravel, and notably flashy after rain. Salmon and sea trout are occasionally seen at Rossett weir but don't hang around; this isn't a migratory-fish river.

  • Limestone karst
The full read · show the working · for brown trout · confidence 80%
How the 18 is built — score × weight = contribution
Temperature10 × 28%2.8
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity63 × 12%7.6
Limiting factor: Water temperature (21.5°C) is outside Brown Trout's preferred range (10–16°C)= 58
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
What would change the calculation
Cooler water — back toward the 10–16 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Related guides
Grayling Playbookgrayling tacticsYorkshire & SpidersNorth Country methodsEuro Nymphingsubsurface methods
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