# List of lakes of Wales

This is a list of lakes in Wales, including those created as reservoirs. The names of most lakes in Wales start with the word "Llyn", which is Welsh for "lake". Except where otherwise referenced, all lakes listed here are named on the relevant Ordnance Survey map at 1:25000 scale.

## By area

In terms of surface area, the ten largest lakes in Wales are
* Bala Lake (Llyn Tegid) — 1,196 acres (4.84 km$^2$)
* Llyn Trawsfynydd — 1,180 acres (4.8 km$^2$)
* Lake Vyrnwy — 1,120 acres (4.5 km$^2$)
* Llyn Brenig — 894 acres (3.62 km$^2$)
* Llyn Celyn — 800 acres (3.2 km$^2$)
* Llyn Alaw — 762 acres (3.08 km$^2$)
* Claerwen Reservoir — 655 acres (2.65 km$^2$)
* Clywedog Reservoir — 601 acres (2.43 km$^2$)
* Nant-y-moch Reservoir — 525 acres (2.12 km$^2$)
* Caban Coch Reservoir — 519 acres (2.10 km$^2$)
All of the above, with the exception of Bala Lake, are reservoirs held back by dams. Bala Lake was the largest natural lake in Wales though its level has been artificially controlled by sluices since about 1804. The largest natural lake in South Wales is Llangorse Lake (Llyn Syfaddan), which is also the second largest natural lake.

## By counties and county boroughs

This list of Welsh lakes ordered by principal areas (counties and county boroughs) includes lakes with a surface area of greater than 5 acres (2.0 ha), but excludes those lakes and ponds created as part of an active industrial site (i.e., works ponds) and also excludes service reservoirs used to store drinking water as part of the water supply system. Grid references identify the approximate centre of the lake or the dam in the case of artificial reservoirs. For some lakes the principal area boundary passes through a lake; in these cases the lake is represented in the list for each appropriate authority. Known occurrences include Llyn Brenig, Pontsticill Reservoir, Llwyn-on Reservoir, Cantref Reservoir and Dol-y-gaer Reservoir. All occurrences are marked with an asterisk (*).

### Anglesey

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### Blaenau Gwent

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### Bridgend

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### Caerphilly

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### Cardiff

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### Carmarthenshire

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### Ceredigion

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### Conwy

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### Denbighshire

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### Flintshire

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### Gwynedd

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### Merthyr Tydfil

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### Monmouthshire

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### Neath Port Talbot

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### Pembrokeshire

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### Powys

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Note: Caban Coch and Garreg-ddu reservoirs are separately named but form one contiguous area of water at normal levels. The area quoted is for the two combined. At high water levels, Pentwyn Reservoir is continuous with Pontsticill Reservoir, its dam being submerged.

### Rhondda Cynon Taf

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### Swansea

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### Torfaen

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### Vale of Glamorgan

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### Wrexham

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## By national park

Lakes and reservoirs within each of Wales' three national parks.

### Brecon Beacons

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### Pembrokeshire Coast

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### Snowdonia

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## By supply to England

Many Welsh lakes supply the nation itself with water, however, some lakes and reservoirs supply England.
The main reservoirs created for this purpose include:
| Reservoir name | Location | Built by | Supplies water to |
| Lake Vyrnwy | Powys | Liverpool Corporation | Liverpool, Cheshire and Manchester |
| Claerwen | Elan Valley reservoirs | Birmingham Corporation Water Department | Birmingham |
| Craig-goch | Elan Valley reservoirs | Birmingham Corporation Water Department | Birmingham |
| Pen-y-garreg | Elan Valley reservoirs | Birmingham Corporation Water Department | Birmingham |
| Garreg-ddu | Elan Valley reservoirs | Birmingham Corporation Water Department | Birmingham, |
| Caban-coch | Elan Valley reservoirs | Birmingham Corporation Water Department | Birmingham |
| Alwen Reservoir | Conwy | The Corporation of Birkenhead | Birkenhead |
| Llyn Celyn (via and Bala Lake) | Gwynedd | Liverpool Corporation Waterworks | Liverpool |
| Llyn Clywedog | Powys | Reed and Mallick of Salisbury | Shropshire, West Midlands to Bristol |

## Former lakes

| Lake name | Catchment | Grid ref. | Status/Use | Principal area |
| Bryn-bach Pond | Sirhowy River | SO122100 | formerly industrial use (not same site as modern lake) | Blaenau Gwent |
| Cairn Mound Impounding Reservoir | River Clydach | SO202136 | former reservoir | Blaenau Gwent |
| Clyn-mil Pond | River Taff | SO062052 | formerly industrial use | Merthyr Tydfil |
| Glyn-dyrys Pond | River Taff | SO049047 | formerly industrial use | Merthyr Tydfil |
| Hirwaun Ponds | River Cynon | SN945060 | formerly industrial use | Rhondda Cynon Taf |
| Lower Neuadd Reservoir | River Taff | SO030180 | former reservoir (dam breached) | Merthyr Tydfil |
| Llyn Nantlle-isaf | Afon Llyfni | SH506528 | natural lake | Gwynedd |
| Pitwellt Pond | River Taff | SO078098 | former reservoir (dam breached) | Merthyr Tydfil |
| Rhyd-y-blew Pond (Rassa) | Ebbw River | SO160112 | formerly industrial use | Blaenau Gwent |
| Scotch Peter's Reservoir | Sirhowy River | SO155088 | former reservoir | Blaenau Gwent |
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