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List of lakes of Wales facts for kids

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This is a list of lakes in Wales. Most lakes in Wales start with the word "Llyn", which is Welsh for "Lake".

By area

In terms of surface area, the ten largest lakes in Wales are

  • Llyn Tegid (Bala Lake) — 1,196 acres (4.84 km2)
  • Llyn Trawsfynydd — 1,180 acres (4.8 km2)
  • Lake Vyrnwy — 1,120 acres (4.5 km2)
  • Llyn Brenig — 894 acres (3.62 km2)
  • Llyn Celyn — 800 acres (3.2 km2)
  • Llyn Alaw — 762 acres (3.08 km2)
  • Claerwen Reservoir — 655 acres (2.65 km2)
  • Llyn Clywedog — 601 acres (2.43 km2)
  • Nant y Moch Reservoir — 525 acres (2.12 km2)
  • Caban Coch Reservoir — 519 acres (2.10 km2)

All of the above, with the exception of Llyn Tegid, are reservoirs held back by dams. Llyn Tegid was the largest natural lake in Wales though its level is now artificially controlled. The largest natural lake in South Wales is Llangors Lake or Llyn Syfaddan, which is also the second largest natural lake.

By unitary authority

This list of Welsh lakes ordered by unitary authority 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 unitary authority 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 (*).


Lake name Catchment Grid ref. Area (acres) Status/Use
Llyn Alaw River Alaw SH375853 762 Water supply to north Anglesey
Llyn Bodgylched No main catchment SH585770
Llyn Cefni Afon Cefni SH443771 167 Water supply to central Anglesey
Llyn Coron No main catchment SH380700 69
Llyn Dinam No main catchment SH312778 24
Llyn y Gors No main catchment SH575748 Amenity (fishing)
Llyn Gwaith-glo No main catchment SH450713
Llyn Llygeirian No main catchment SH347898
Llyn Llywenan No main catchment SH347815
Llyn Llwydiarth Afon Braint SH549786
Llyn Maelog No main catchment SH325730 65 Former water supply to Rhosneigr
Llyn Pen y Parc No main catchment SH585751 Water supply (disused)
Llyn Penrhyn No main catchment SH313770 55 RSPB bird reserve
Llyn Rhosddu No main catchment SH425648
Llyn Traffwll No main catchment SH325770 91
Llyn Treflesg No main catchment SH307770 RSPB bird reserve

Blaenau Gwent

Lake name Catchment Grid ref. Area (acres) Status/Use
Carno Reservoir Ebbw River SO164131 reservoir
Cwmtillery Reservoir Ebbw River SO220071 reservoir
Rhyd-y-blew Pond Ebbw River SO160112
Parc Brynbach lake Sirhowy River SO127101 amenity
Scotch Pete's Reservoir Sirhowy River SO155088 reservoir
Shon-Sheffrey's Reservoir Sirhowy River SO158116 reservoir


Lake name Catchment Grid ref. Area (acres) Status/Use
Kenfig Pool River Kenfig SS797815 70 Natural lake


Lake name Catchment Grid ref. Area (acres) Status/Use
Lower Blaen Rhymney Reservoir Rhymney River SO103103 reservoir
Upper Blaen Rhymney Reservoir Rhymney River SO098104 reservoir
Bute Town Reservoir Rhymney River SO101091
Nant-y-draenog Reservoir Sirhowy River ST188935 5 reservoir
Parc Cwm Darran Lake Rhmney River ST117032 amenity
Rhaslas Pond Rhymney River SO095072
Ffrwd Farm lake (west) Rhymney River ST154920 angling
Ffrwd Farm lake (east) Rhymney River ST155920 angling


Lake name Catchment Grid ref. Area (acres) Status/Use
Cardiff Bay River Taff ST190726 Amenity
Hendre Lake Faendre Reen ST245805 12 Recreation and amenity
Llanishen Reservoir Rhymney River ST185815 Water supply to Cardiff
Lisvane Reservoir Rhymney River ST189822 Water Supply to Cardiff
Roath lake Rhymney River ST184795 Recreation and amenity


Lake name Catchment Grid ref. Area (acres) Status/Use
Llyn Brianne River Tywi SN790485 530 Regulation reservoir
Garn Ffrwd pond? Gwendraeth Fach SN508142 5
Llanelli North Dock lake coastal water body SS498996 amenity (former dock)
Llyn Llech Owen Reservoir Gwendraeth Fawr SN568151 amenity/reservoir
Cwm Lliedi Reservoir Afon Lliedi SS519036 ex water supply
Llyn y Fan Fach River Tywi SN803219
Llyn Taliaris Afon Dulais SN634283
Lower Talley Lake Afon Cothi SN633331 natural lake
National Wetlands Centre coastal water bodies SS529986 conservation/wildlife
Old Castle Pond/Pond Twym coastal lake SN500003 amenity
Sandy Water coastal lake SN495003 amenity
Upper Lliedi Reservoir Afon Lliedi SS511045 reservoir
Upper Talley Lake Afon Cothi SN631337 natural lake
Usk Reservoir River Usk SN832288 Water supply
un-named lake coastal lake SS507987 amenity


Lake name Catchment Grid ref. Area (acres) Status/Use
Llyn Berwyn River Teifi SN743569 40 Natural lake
Llyn Craigpistyll River Dyfi SN722858 Natural lake
Dinas Reservoir River Rheidol SH000000 Hydroelectricity
Llyn Du River Severn SN800698 Natural lake
Llyn Egnant River Teifi SN792674 Water supply
Falcondale Lake River Teifi SN563491 Amenity
Llyn Frongoch River Ystwyth SN721752 Lead mining ?/ Natural
Llyn Fyrddon Fach River Severn SN796701 Natural lake
Llyn Fyrddon Fawr River Severn SN800708 Natural lake
Llyn Glandwgan River Ystwyth SN707752 Natural lake
Glanmerin Lake River Dyfi SN755990 Natural lake
Llyn y Gorlan River Teifi SN786670 Water supply
Llyn Gwngi River Severn SN839729 Natural lake
Llyn Hir River Teifi SN789676 Water supply
Nant-y-moch Reservoir River Rheidol SN870636 Hydroelectricity
Llyn Rhosrhydd River Ystwyth SN705759 Natural lake
Llyn Syfydrin River Rheidol SN723848 Natural lake
Llyn Teifi River Teifi SN781675 Water supply


Lake name Catchment Grid ref. Area (acres) Status/Use
Aled Isaf Reservoir River Clwyd SH912594 65.7 Water supply
Llyn Aled River Clwyd SH917574 112.7 Water supply
Llyn Alwen River Dee SH898565 65
Alwen Reservoir River Dee SH943538 372.9 Water supply
Llyn Bochlwyd River Ogwen SH654592 10
Llyn Bodgynydd SH760592 14 Industrial supply (disused)
Llyn Brenig River Dee SH973555 920 Flow regulation
Llyn Coedty River Conwy SH754666 11.6 Hydroelectricity
Llyn Conwy River Conwy SH780462 101.3 Water supply for Llanrwst
Llyn Cowlyd River Conwy SH727624 269 Water supply for Conwy
Llyn Crafnant River Conwy SH749610 52 Former water supply for Trefriw
Dulyn Reservoir River Conwy SH700665 33 Water supply
Llyn Eigiau River Conwy SH720651 120
Llyn Elsi River Conwy SH783552 26 Water supply for Betws-y-coed
Llyn Geirionydd River Conwy SH763608 45
Llyn Goddionduon River Conwy SH753586 10
Ffynnon Lloer River Ogwen SH662621 6
Ffynnon Llugwy River Conwy SH692627 40
Llynnau Mymbyr River Conwy SH000000 58
Llyn Ogwen River Ogwen SH659604 78
Llyn y Parc River Conwy SH792588 22
Llyn-y-foel Afon Lledr SH714547 natural lake


Lake name Catchment Grid ref. Area (acres) Status/Use
Brickfields Pond River Clwyd SJ012803 8.9 Local nature reserve
Llyn Brân SH961592 31.4
Llyn Brenig River Dee SH973555 920 Flow regulation
Llyn Cyfynwy SJ217546 17.5
Llyn Gweryd SJ172550 13.1
Llyn Mynyllod SJ012402 6.2
Nant-y-Ffrith Reservoir SJ242530 12.1
Pendinas Reservoir SJ235518 16.3
Rhyl Marine Lake River Clwyd SH999804 28.7
unnamed lake on Rûg estate River Dee SJ058440 8.4


Lake name Catchment Grid ref. Area (acres) Status/Use
Llyn Helyg River Clwyd SJ113772 37
Padeswood Pool SJ278619 12.6 angling
Shotwick Lake River Dee SJ315725 amenity
unnamed reservoir, Cilcain SJ155641 5.4
unnamed reservoir, Oakenholt SJ262710 5.7
Ysceifiog Lake SJ147716 13.8


Lake name Catchment Grid ref. Area (acres) Status/Use
Llyn yr Adar River Glaslyn SH655479 10
Llyn Anafon Afon Aber SH698698 13 Water supply
Llyn Arenig Fach SH827417 34 Natural lake
Llyn Arenig Fawr River Dee SH846380 84 water supply for Bala town, natural lake
Llynnau Barlwyd River Dwyryd SH710484 10 + 5 Industrial water supply
Llyn y Bi River Mawddach SH669264 6
Llyn Bodlyn Afon Ysgethin SH648239 42 Water supply
Llyn Bowydd River Dwyryd SH725467 22 Industrial water supply.
Llyn Caerwych River Dwyryd SH640350 5
Llyn Cau River Dysynni SH714123 33
Llyn Celyn River Dee SH000000 815 River Regulation
Llyn Conglog River Dwyryd SH674473 18
Llyn Conglog Mawr River Dwyryd SH758387 8
Craiglyn Dyfi also written as Creiglyn Dyfi River Dyfi SH867225 15 Natural corrie lake
Llyn Croesor River Glaslyn SH661457 5
Llyn Cwm Corsiog SH663470 7 Industrial water supply (disused)
Llyn Cwellyn Afon Gwyrfai SH559549 215 Water supply
Llyn Cwm Bychan Afon Artro SH640312 25
Llyn Cwm Dulyn Afon Llyfni SH492495 34 Water supply
Llyn Cwmffynnon River Conwy SH649562 20
Llyn Cwm-mynach River Mawddach SH678237 14
Llyn Cwmorthin River Dwyryd SH677463 22
Llynnau Cwm Silyn Afon Llyfni SH513508 15 + 15
Llyn Cwm y Foel River Glaslyn SH655468 8
Llyn Cwmystradllyn River Dwyfor SH561444 98 Natural lake
Llyn Cynwch River Mawddach SH737207 26 Amenity
Llyn Dinas River Glaslyn SH616495 60 Natural lake
Llynnau Diwaunedd River Conwy SH682537 19 + 13 Natural lakes
Llyn Dulyn Afon Ysgethin SH661244 5 Natural lake, reservoir
Llyn Du'r Arddu River Seiont SH600557 5 Natural lake
Llyn Dwythwch River Seiont SH570580 24
Llyn y Dywarchen Afon Gwyrfai SH560534 40
Llyn Edno River Glaslyn SH62497 10
Llyn Eiddew-mawr Afon Artro SH646338 22
Llyn Ffynnon y Gwas Afon Gwyrfai SH591553 10
Llyn y Gadair Afon Gwyrfai SH568521 50
Llyn Gwynant River Glaslyn SH644519 85
Llyn Hesgyn River Dee SH885442 5
Llyn Hywel SH663266 13
Llyn Idwal River Ogwen SH645596 28
Llyn Llagi River Glaslyn SH649482 8
Llyn Llydaw River Glaslyn SH629543 110
Llyn Llywelyn River Glaslyn SH562499 6
Llyn Mair River Dwyryd SH652412 14
Marchlyn Bach reservoir River Seiont SH607625
Marchlyn Mawr River Seiont SH615622 Hydroelectricity
Llyn Mwyngil (Talyllyn Lake) River Dysynni SH717099 220
Llyn Nantlle Uchaf Afon Llyfni SH514530 80
Llyn Newydd River Dwyryd SH722471 12
Llyn Peris River Seiont SH591595 95
Llyn Padarn River Seiont SH572613 280 Hydroelectricity
Tanygrisiau Reservoir River Dwyryd SH679441 95
Llyn Tecwyn Isaf SH629370 7
Llyn Tecwyn Uchaf River Dwyryd SH640381 31
Llyn Tegid – (Bala Lake) River Dee SH911338 1,196
Llyn Teyrn River Glaslyn SH641547 5
Llyn Trawsfynydd River Dwyryd SH674377 1,180 Nuclear and Hydroelectricity
Llyn Tryweryn River Dee SH788384 20
Llyn Wylfa SH000000 6

Merthyr Tydfil

Lake name Catchment Grid ref. Area (acres) Status/Use
Cantref Reservoir * River Taff SN996154 Water supply
Cyfarthfa Castle Lake River Taff SO039073 amenity
Dol-y-gaer Reservoir * (Pentwyn Reservoir) River Taff SO060118 Water supply
Llwyn-on Reservoir * River Taff SO012113 Water supply
Penywern Middle Pond River Taff SO073083 angling
Penywern Top Pond River Taff SO071086 angling
Pitwellt Pond River Taff SO078098 former reservoir (dam breached)
Pontsticill Reservoir * River Taff SO060118 Water supply


Lake name Catchment Grid ref. Area (acres) Status/Use
Llandegfedd reservoir River Usk ST325985 434 Water supply
Pwll Pen-ffordd-goch/Keepers Pond River Usk SO255109 Amenity. Former reservoir for Garn-ddyrys ironworks
Wentwood reservoir River Usk ST430929 41 Water supply

Neath Port Talbot

Lake name Catchment Grid ref. Area (acres) Status/Use
Cwmwernderi Reservoir SS817902 reservoir
Eglwys Nunydd River Afan SS791855 260 Industrial water supply + fishing
Furzemill Pond River Afan SS810857 5 former millpond?
Rheola Pond River Neath SN843043
larger un-named lake at Aberclwyd River Neath SN847043 amenity
smaller un-named lake at Aberclwyd River Neath SN852045 amenity


Lake name Catchment Grid ref. Area (acres) Status/Use
Bosherston lakes Coastal stream SR974946 Natural lakes
Llys-y-Frân Reservoir Western Cleddau SN036242 212 Water supply
Rosebush Reservoir Western Cleddau SN061291 30 Water supply


Lake name Catchment Grid ref. Area (acres) Status/Use
Beacons Reservoir River Taff SN987182 52 Water supply
Caban-coch Reservoir River Severn SN924645 500 (including Garreg-ddu Reservoir) Water supply
Cantref Reservoir * River Taff SN996154 42 Water supply
Claerwen Reservoir River Severn SN869963 664 Water supply
Llyn Clywedog River Severn SN911870 River regulation
Craig-goch Reservoir River Severn SN893686 217 Water supply
Cray Reservoir River Usk SN883220 100 Water supply
Dol-y-gaer Reservoir * (Pen-twyn Reservoir) River Taff SO054144 Water supply
Garreg-ddu Reservoir River Severn SN911639 500 (including Caban-coch Reservoir) Water supply
Llyn Gludy River Usk SO018298
Llangorse Lake River Usk SO132266 327 Natural lake
Llwyn-on Reservoir * River Taff SO012113 150 Water supply
Llyn y Fan Fawr River Tawe SN832216
Lower Neuadd Reservoir River Taff SO030180 Water supply
Upper Neuadd Reservoir River Taff SO029188 Water supply
Penygarreg Reservoir River Severn SN911673 124 Water supply
Pontsticill Reservoir * River Taff SO060118 Water supply
Talybont Reservoir River Usk SO104205 Water supply
Ty Mawr Pool River Usk SO074264 natural lake
Lake Vyrnwy River Vyrnwy SH000000 Water supply
Ystradfellte Reservoir River Neath SN955175 Water supply

Rhondda Cynon Taff

Lake name Catchment Grid ref. Area (acres) Status/Use
Dare Valley Country Park lower lake Afon Cynon SN977028 amenity
Lluest-wen Reservoir Afon Rhondda Fach SN947017
Llyn Fawr River Taff SN917034 24
Nant-hir Reservoir Afon Cynon SN989069
Nant-moel Reservoir Afon Cynon SN982071
Penderyn Reservoir River Neath SN938072
?Perthgelyn Reservoir Afon Cynon ST053970 reservoir


Lake name Catchment Grid ref. Area (acres) Status/Use
Lake Fendrod River Tawe SS676967 13 Amenity
Lower Lliw Reservoir River Lliw SN650036 Water Supply
Oxwich Marsh Lake coastal stream SS503873 >15 Natural lake
Upper Lliw Reservoir River Lliw SN661062 Water Supply
Tawe Barrage River Tawe SH664926 Amenity
Specimen Lake River Loughor SN598056 10 amenity/angling


Lake name Catchment Grid ref. Area (acres) Status/Use
Blaen Bran Reservoir (lower) Afon Lwyd ST267971
Coity Pond Afon Lwyd SN233090 former reservoir

Vale of Glamorgan

Lake name Catchment Grid ref. Area (acres) Status/Use
Cosmeston Lake River Cadoxton ST176692 Amenity
Hensol Lake River Ely ST045789 Amenity and reservoir
Hensol Mill Pond River Ely ST050790 6 former mill pond


Lake name Catchment Grid ref. Area (acres) Status/Use
Cae Llwyd Reservoir SJ270479 10.6
Chirk Castle Lake SJ269386 11.1
Fenn's Bank Mere SJ505386 8.4
Gresford Flash SJ346536 8.2 amenity
Hanmer Mere SJ452392 45.2 natural lake
Monk's Pool SJ303448 5.2
Pant-yr-ochain Lake SJ349529 14.1
Penycae Top Reservoir SJ267452 6.2
Ty Mawr Reservoir SJ276480 21.3
Wynnstay Park Lake SJ307428 8.9
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