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 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 unitary authority. This list of Welsh lakes ordered by unitary authority 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 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 (*). Powys. 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. By national park. Lakes and reservoirs within each of  Wales' three national parks. By supply to England. Most Welsh lakes supply the nation itself with water, however, there are lakes and reservoirs which supply England. The main reservoirs created for this purpose include: