Spate · Old Red Sandstone · Wales / Brecon Beacons (Tawe tributary)

Afon Twrch

The Afon Twrch, a small upland river, winding through a moorland valley in the Brecon Beacons

The Twrch is the main tributary of the Tawe — small, double-bank, and known to those who know it as one of the best-kept brown trout secrets in south Wales.

Poor · Brown Trout
Pheasant Tail Nymph · 14-16
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 temp21.4°C
  • ClarityClear
Today's fly
Pheasant Tail Nymph
Pheasant Tail Nymph14-16
Upstream, sub-surface
Conditions on the water
Estimate
Level
Dry recently
No gauge reading
Water temp21.4°C
ClarityClear
Weather23°C
WindN 15 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
21°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 21.4°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots.
Hatch timeline · todayQuiet day

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Sub-surface · on the nymphunder the surface

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Beyond the hatch · worth watchingambient prey

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Evidence
Survey-backed · regionalHigh 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
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.

Ranked for today
Brown Trout fly box
Beats · 1
Afon Twrch — Beats 1 & 2 via Fishing PassportAccess varies
Two short day-ticket beats on the Twrch — Beat 1 (¾ mile) and Beat 2 (½ mile) — both double bank.
What's coming
Plan ahead
5-day outlook
Water here around 21°C. Nothing cooler within range — carry a thermometer.
Gallery · 3
  1. The Afon Twrch, a small upland river, winding through a moorland valley in the Brecon Beacons
    The Afon Twrch winding through moorland above Ystradgynlais
  2. River Twrch looking south downstream from the side of Pen yr Helyg
    River Twrch looking south downstream from the side of Pen yr Helyg
  3. Terrain map of the venue
    Terrain map
About this water

The Twrch is the main tributary of the Tawe — small, double-bank, and known to those who know it as one of the best-kept brown trout secrets in south Wales. Two short Passport beats (¾ mile and ½ mile), seventeen quid a day, five for juniors. The kind of small Brecon Beacons spate water that rewards quiet wading and small flies. The Tawe gets the headlines; the Twrch quietly fishes.

  • Old red sandstone
The full read · show the working · for Brown Trout · confidence 80%
How the 19 is built — score × weight = contribution
Temperature11 × 28%3.1
Flow60 × 22%13.2
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity52 × 12%6.2
Limiting factor: Water temperature (21.4°C) is outside Brown Trout's preferred range (10–16°C)= 52
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
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.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout3 March → 30 September
Related guides
Yorkshire & SpidersNorth Country methodsEuro Nymphingsubsurface methods
Booking & contacts