List of lakes of Wales

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 (*).

Anglesey

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

Bridgend

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

Caerphilly

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

Cardiff

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

Carmarthenshire

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

Ceredigion

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		Hydrolectricity
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

Conwy

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

Denbighshire

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

Flintshire

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

Gwynedd

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

Monmouthshire

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

Pembrokeshire

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

Powys

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

Swansea

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

Torfaen

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

Wrexham

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