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Fishing Llwyn-on Reservoir: what the data says
133-acre lake near Merthry Tydfil. The lake tops out around 72 ft. Contours on this water are modeled from its actual shoreline and max depth. Good for finding likely water, never for navigation. The season-by-season read for each species follows, from the map's own numbers.
On the chart, Llwyn-on Reservoir draws 133 acres inside 2.4 miles of shoreline. The shoreline is moderately structured (index 1.5) — enough points and pockets to pattern. Roughly 23% of the water is 15 ft or less as modeled, the band where the food chain lives.
Brown Trout fishing at Llwyn-on Reservoir
When the water first warms, brown trout slide up into 3 to 25 ft. By summer they slide out to 25 to 60 ft, and by winter most fish are in 5 to 35 ft. If you only fish one area, make it Break off the point: a drop-off around 32 ft that scores prime in summer. In summer the feeding windows fall in after dark and early morning. Keep a spoon at the thermocline or a deep stickbait (night) rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 25 ft | dawn & dusk | Main-lake point (18 ft) | Stickbait off planer boards (shallow), Small spoon along mud lines |
| Summer | 25 to 60 ft | night & dawn | Break off the point (32 ft) | Spoon at the thermocline, Deep stickbait (night) |
| Fall | 5 to 30 ft | dusk & dawn | Main-lake point (18 ft) | Jerkbait over gravel, Casting spoon |
| Winter | 5 to 35 ft | dawn | Break off the point (32 ft) | Jigging spoon, Small stickbait (slow) |
European Perch fishing at Llwyn-on Reservoir
Start shallow in spring: european perch sit in 3 to 12 ft that time of year. Summer pushes them deeper, 8 to 28 ft, and winter fish settle into 12 to 33 ft. The spot to know is Shallow bay flat, a weed flat in about 6 ft of water that rates prime for european perch in spring. Warm-month bites cluster around early morning. Throw a drop-shot micro plastics or a small crankbait (perch pattern) until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (6 ft) | Small jig + curly tail, Inline spinner #1-2 |
| Summer | 8 to 28 ft | dawn | Shallow bay flat (6 ft) | Drop-shot micro plastics, Small crankbait (perch pattern) |
| Fall | 10 to 33 ft | midday | Break off the point (32 ft) | Jigging spoon (small), Drop-shot on deep flats |
| Winter | 12 to 33 ft | midday & dawn | Break off the point (32 ft) | Tungsten jig + maggots, Small balance jig |
Northern Pike fishing at Llwyn-on Reservoir
The spring pattern is a shallow one: northern pike in 2 to 8 ft. Midsummer fish sit out in 8 to 20 ft before dropping to 5 to 15 ft for winter. The spot to know is Shallow bay flat, a weed flat in about 6 ft of water that rates prime for northern pike in spring. Plan around early morning and the evening in the warm months. Summer baits: a bucktail or a weedless spoon over cabbage gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (6 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Shallow bay flat (6 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (6 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (6 ft) | Tip-ups, Large jigging spoon |
Arctic Char fishing at Llwyn-on Reservoir
Spring arctic char on Llwyn-on Reservoir hold shallow, usually 4 to 15 ft. They move out to 20 to 60 ft in summer and finish the year down in 10 to 40 ft. Put Deep basin first on the milk run — a deep basin near 61 ft that grades prime for summer. The feeding windows run early morning. The summer box starts with a jigging spoon vertical or a tube jig (smelt).
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | midday & dawn | open water | Small casting spoon (silver/orange), Jerkbait (small) |
| Summer | 20 to 60 ft | dawn | Deep basin (61 ft) | Jigging spoon vertical, Tube jig (smelt) |
| Fall | 8 to 30 ft | midday & dusk | Break off the point (32 ft) | Casting spoon (orange/gold), Beadhead streamer |
| Winter | 10 to 40 ft | midday & dawn | Break off the point (32 ft) | Jigging spoon (glow/silver), Tungsten jig + plastic |
Notable structure
- Deep basin: deep basin, around 61 ft
- Break off the point: drop-off, around 32 ft
- Main-lake point: point, around 18 ft
- Secondary point: point, around 18 ft
- Shallow bay flat: weed flat, around 6 ft
- Back-bay flat: weed flat, around 6 ft
Common questions
How deep is Llwyn-on Reservoir?
Llwyn-on Reservoir is about 72 ft (22 m) deep at its deepest point. The contours here are modeled from the water's real shape and maximum depth, so treat them as a rough guide.
What fish are in Llwyn-on Reservoir?
Anglers target northern pike, european perch, brown trout, arctic char on Llwyn-on Reservoir. This isn't a survey of the water — none is published for it — but an informed estimate from the species common to the region, narrowed by this water's depth, size and each species' range.
Where is the best fishing spot on Llwyn-on Reservoir?
Shallow bay flat is the top-rated area: a weed flat in about 6 ft of water that rates prime for european perch in spring. Scroll up to the map for the complete spot list by species and season.
When is the best time to fish Llwyn-on Reservoir?
For brown trout, the summer bite is best in after dark and early morning. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Nearby waters
Llyn Fach 8 mi · Llangorse Lake 12 mi · Llyn y Fan Fawr 12 mi · Usk Reservoir 15 mi · Llan Bwch-llyn Lake 22 mi · Kenfig Pool 23 mi · Upper Talley Lake 27 mi · Lower Talley Lake 27 mi · Llyn Llech Owain 27 mi · Llyn Berwyn 32 mi · Llyn Gynon 35 mi · Llyn Pencarreg 36 mi
See how Llwyn-on Reservoir stacks up: best northern pike lakes in United Kingdom · best european perch lakes in United Kingdom · best brown trout lakes in United Kingdom · best arctic char lakes in United Kingdom
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