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.Ordnance Survey maps. 1:25000
By area In terms of surface area, the ten largest lakes in Wales are Llyn Tegid (Bala Lake) — Llyn Trawsfynydd — Lake Vyrnwy — Llyn Brenig — Llyn Celyn — Llyn Alaw — Claerwen Reservoir — Clywedog Reservoir — Nant-y-moch Reservoir — Caban Coch Reservoir —
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 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 , 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
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresLlyn AlawRiver Alaw water supply to north AngleseyLlyn BodgylchedNo main catchment Llyn CefniAfon Cefni water supply to central AngleseyLlyn CoronNo main catchment Llyn DinamNo main catchment Llyn y GorsNo main catchment amenity (fishing)Llyn Gwaith-gloNo main catchment Llyn LlygeirianNo main catchment Llyn LlywenanNo main catchment Largest natural body of water on AngleseyLlyn LlwydiarthAfon Braint Llyn MaelogNo main catchment former water supply to RhosneigrLlyn Pen y ParcNo main catchment water supply (disused)Llyn PenrhynNo main catchment RSPB bird reserveLlyn RhosdduNo main catchment Llyn TraffwllNo main catchment Llyn TreflesgNo main catchment RSPB bird reserve
Blaenau Gwent
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresBlaen-y-Cwm Reservoir (Blaen Clydach Reservoir)Ebbw River/River Clydach Reservoir, originally constructed in 1813 to supply the Nantyglo Ironworks.Carno ReservoirEbbw River reservoirCwmtillery ReservoirEbbw River reservoirLower Boat PondEbbw River amenity, formerly industrial supply along with smaller Upper Boat PondRhyd-y-blew PondEbbw River Parc Brynbach lakeSirhowy River amenityShon-Sheffrey's ReservoirSirhowy River reservoir
Bridgend
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresKenfig PoolRiver Kenfig natural lakeCraig yr Aber ReservoirNant Craig yr Aber man-made dam
Caerphilly
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresLower Blaen Rhymney ReservoirRhymney River reservoirUpper Blaen Rhymney ReservoirRhymney River reservoirBute Town ReservoirRhymney River Caerphilly Castle moatRhymney River Nant-y-draenog ReservoirSirhowy River reservoirParc Cwm Darran LakeRhymney River amenityRhaslas PondRhymney River Ffrwd Farm lake (west)Rhymney River anglingFfrwd Farm lake (east)Rhymney River anglingPen-y-fan PondSirhowy River built as canal feed reservoir.
Cardiff
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresCardiff BayRiver Taff/River Ely amenityHendre LakeNo main catchment recreation and amenityLlanishen ReservoirRhymney River water supply to CardiffLisvane ReservoirRhymney River water supply to CardiffRoath lakeRhymney River recreation and amenity
Carmarthenshire
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresLlyn BrianneRiver Tywi regulation reservoirGarn Ffrwd pond?Gwendraeth Fach Llanelli North Dock lakeCoastal waterbody amenity (former dock)Llyn Llech Owen ReservoirGwendraeth Fawr amenity/reservoirCwm Lliedi ReservoirAfon Lliedi ex water supplyLlyn y Fan FachRiver Tywi naturalLlyn TaliarisAfon Dulais Lower Talley LakeAfon Cothi natural lakeLagoons at National Wetlands CentreCoastal waterbodies conservation/wildlifeOld Castle Pond/Pond TwymCoastal lake AmenitySandy WaterCoastal lake amenityUpper Lliedi ReservoirAfon Lliedi reservoirUpper Talley LakeAfon Cothi natural lakeUsk ReservoirRiver Usk water supplyDelta LakeCoastal lake amenity
Ceredigion
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresLlyn BachRiver Teifi natural lakeLlyn BerwynRiver Teifi natural lakeLlyn CraigypistyllRiver Dyfi natural lakeDinas ReservoirRiver Rheidol hydroelectricity Llyn DuRiver Severn natural lakeLlyn EgnantRiver Teifi water supplyFalcondale LakeRiver Teifi amenityLlyn FrongochRiver Ystwyth lead mining ?/ naturalLlyn Fyrddon FachRiver Severn natural lakeLlyn Fyrddon FawrRiver Severn natural lakeLlyn GlandwganRiver Ystwyth natural lakeLlyn y GorlanRiver Teifi water supplyLlyn GwngiRiver Severn natural lakeLlyn GynonRiver Severn natural lakeLlyn HirRiver Teifi water supplyNant-y-moch ReservoirRiver Rheidol hydroelectricity Llyn Pond GwaithRiver Teifi NaturalLlyn RhosrhyddRiver Ystwyth natural lakeLlyn SyfydrinRiver Rheidol natural lakeLlyn TeifiRiver Teifi water supply
Conwy
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresAled Isaf ReservoirRiver Clwyd water supplyLlyn AledRiver Clwyd water supplyLlyn AlwenRiver Dee Alwen ReservoirRiver Dee water supplyLlyn BochlwydRiver Ogwen Llyn BodgynyddRiver Conwy industrial supply (disused)Llyn BrenigRiver Dee flow regulationLlyn CoedtyRiver Conwy hydroelectricityLlyn ConwyRiver Conwy water supply for LlanrwstLlyn CowlydRiver Conwy water supply for ConwyLlyn CrafnantRiver Conwy former water supply for Trefriw and LlanrwstDulyn ReservoirRiver Conwy water supplyLlyn EigiauRiver Conwy Llyn ElsiRiver Conwy water supply for Betws-y-coedLlyn GeirionyddRiver Conwy Llyn GoddionduonRiver Conwy Llyn y Foel-frechRiver Clwyd Tiny natural lakeFfynnon LloerRiver Ogwen Ffynnon LlugwyRiver Conwy Llynnau MymbyrRiver Conwy Llyn OgwenRiver Ogwen Llyn y ParcRiver Conwy Llyn-y-foelAfon Lledr natural lake
Denbighshire
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresBrickfields PondRiver Clwyd Local nature reserveLlyn Brân naturalLlyn BrenigRiver Dee flow regulationLlyn Cyfynwy Llyn Gweryd Llyn Mynyllod Nant-y-Ffrith ReservoirRiver Cegidog Pendinas ReservoirRiver Cegidog Rhyl Marine LakeRiver Clwyd unnamed lake on Rûg estateRiver Dee
Flintshire
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresLlyn HelygRiver Clwyd Padeswood Pool anglingShotwick LakeRiver Dee amenityunnamed reservoir, Cilcain unnamed reservoir, Oakenholt Ysceifiog Lake
Gwynedd
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresLlyn yr AdarRiver Glaslyn Llyn AnafonAfon Aber water supplyLlyn Arenig Fach natural lakeLlyn Arenig FawrRiver Dee water supply for Bala town, natural lakeLlynnau BarlwydRiver Dwyryd industrial water supply Llyn y BiRiver Mawddach Llyn BodlynAfon Ysgethin water supply Llyn BowyddRiver Dwyryd industrial water supply.Llyn CaerwychRiver Dwyryd Llyn CauRiver Dysynni Llyn CelynRiver Dee river regulation Llyn ConglogRiver Dwyryd Llyn Conglog MawrRiver Dwyryd Craiglyn Dyfi also written as Creiglyn DyfiRiver Dyfi natural corrie lakeLlyn CroesorRiver Glaslyn Llyn Cwm CorsiogAfon Dwyryd industrial water supply (disused) Llyn CwellynAfon Gwyrfai water supply, naturalLlyn Cwm BychanAfon Artro Llyn Cwm DulynAfon Llyfni water supplyLlyn CwmffynnonRiver Conwy Llyn Cwm-mynachRiver Mawddach Llyn CwmorthinRiver Dwyryd Llynnau Cwm SilynAfon Llyfni Llyn Cwm y FoelRiver Glaslyn Llyn CwmystradllynRiver Dwyfor natural lakeLlyn CynwchRiver Mawddach amenityLlyn DinasRiver Glaslyn natural lakeLlynnau DiwauneddRiver Conwy natural lakesLlyn DulynAfon Ysgethin natural lake, reservoirLlyn Du'r ArdduRiver Seiont natural lakeLlyn DwythwchRiver Seiont Llyn y DywarchenAfon Gwyrfai Llyn EdnoRiver Glaslyn Llyn Eiddew-mawrAfon Artro Llyn Ffynnon y GwasAfon Gwyrfai Llyn y GadairAfon Gwyrfai Llyn GwynantRiver Glaslyn Llyn HesgynRiver Dee Llyn Hywel Llyn IdwalRiver Ogwen Llyn IrddynAfon Ysgethin natural lakeLlyn LlagiRiver Glaslyn Llyn LlydawRiver Glaslyn Llyn LlywelynRiver Glaslyn Llyn MairRiver Dwyryd Artificial lakeLlyn ManodRiver Dwyryd Llyn ManodMarchlyn Bach reservoirRiver Seiont Marchlyn MawrRiver Seiont hydroelectricityLlyn Mwyngil (Talyllyn Lake)River Dysynni Llyn Nantlle UchafAfon Llyfni Llyn NewyddRiver Dwyryd Llyn PerisRiver Seiont lower reservoir for pump storage hydro-electricityLlyn PadarnRiver Seiont natural lake used for recreationTanygrisiau ReservoirRiver Dwyryd Llyn Tecwyn Isaf Llyn Tecwyn UchafRiver Dwyryd Llyn Tegid (Bala Lake)River Dee Largest natural water in WalesLlyn TeyrnRiver Glaslyn Llyn TrawsfynyddRiver Dwyryd nuclear power (formerly) and hydroelectric energyLlyn TrywerynRiver Dee Llyn WylfaAfon Mawddach natural lake
Merthyr Tydfil
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresCyfarthfa Castle LakeRiver Taff amenityDol-y-gaer (or Pentwyn) Reservoir *River Taff water supplyLlwyn-on Reservoir *River Taff water supplyPenywern Middle PondRiver Taff angling Penywern Top PondRiver Taff angling Pontsticill Reservoir *River Taff water supply
Monmouthshire
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresLlandegfedd ReservoirRiver Usk water supplyPwll Pen-ffordd-goch / Keepers PondRiver Usk amenity, formerly served Garn-ddyrys ironworksWentwood ReservoirRiver Usk water supply
Neath Port Talbot
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresCwmwernderi Reservoir reservoirEglwys NunyddRiver Afan industrial water supply, fishingFurzemill PondRiver Afan former millpond?Llyn FachRiver Neath Natural lakeRheola PondRiver Neath larger un-named lake at AberclwydRiver Neath amenitysmaller un-named lake at AberclwydRiver Neath amenity
Pembrokeshire
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresBosherston LakesCoastal stream artificialLlys-y-Frân ReservoirWestern Cleddau water supplyRosebush ReservoirWestern Cleddau water supply
Powys
Lake nameCatchmentGrid ref.AreaSatatus/Use Acres HectaresAbernant LakeRiver Irfon Created in 1903 by damming an oxbow of the IrfonBeacons ReservoirRiver Taff water supplyRiver Dyfi NaturalCaban-coch ReservoirRiver Severn water supply. See note regarding areaCantref Reservoir *River Taff water supplyLlyn CarwRiver Wye tiny natural lakeClaerwen ReservoirRiver Severn water supplyLlyn ClywedogRiver Severn river regulationCraig-goch ReservoirRiver Severn water supplyCray ReservoirRiver Usk water supplyLlyn Cwm LlwchRiver Usk tiny glacier lakeDol-y-gaer (or Pentwyn) Reservoir *River Taff water supplyGarreg-ddu ReservoirRiver Severn water supply. See note regarding areaLlyn GlanmerinRiver Dyfi natural lakeRiver Dyfi Llyn GludyRiver Usk Llan Bwch-llyn LakeRiver Wye Mesotrophic lake. Area is approximate.Llangorse LakeRiver Usk natural lake, largest in South WalesLlangynidr ReservoirEbbw River reservoirLlyn LluncawsAfon Tanat natural lakeLlyn y Fan FawrRiver Tawe Upper Neuadd ReservoirRiver Taff water supplyPenygarreg ReservoirRiver Severn water supplyPontsticill Reservoir*River Taff water supplyPwll gwy-rhocRiver Clydachnatural lake. Area is approximate.Talybont ReservoirRiver Usk water supplyTy Mawr PoolRiver Usk natural lakeLake Vyrnwy River Vyrnwy water supplyYstradfellte ReservoirRiver Neath water supply
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