Reservoirs of Wales

There are a large number of reservoirs in Wales reflecting the need for the supply of water for both industry and for consumption, both within the country itself and in neighbouring England. A number also provide hydroelectricity and many old reservoirs also provided motive power for industries, especially for the processing of minerals such as metal ores and slate.

Wales has a relatively high rainfall and significant areas of mountainous topography which are sparsely populated which ensures that water is a plentiful natural resource. Much of the south and east of England has significantly lower rainfall^[1] and a high population density which puts significant strain on the water supply infrastructure there. Collecting water in deep valleys with high river flows is far more efficient that trying to collect sparse rainfall in a generally flat landscape. Because of this engineers have viewed Wales as a potential supply of water. The rapidly growing populations of the industrial centres of Britain in the Industrial Revolution made the need for high volume supplies of clean water even more important and Wales was seen as the ideal source. Such engineering and economic views paid scant regard to the social, cultural and linguistic impacts that the constructions of large reservoirs in Wales would create.

Some reservoirs have been formed by the raising of dams on water courses, others are natural water bodies, the levels of which have been raised to various degrees both for direct supply of water or else for regulation of supply with water being extracted from the river some way downstream. Many reservoirs which were constructed for one purpose e.g. industry, may now serve different or additional purposes e.g amenity or, as in many cases, have been abandoned entirely. Reservoirs range in size with many under 1 acre in area serving local needs, up to Llyn Trawsfynydd which extends to 1,128 acres (456 ha). Bala Lake (Llyn Tegid) is a natural lake which at 1,192 acres (482 ha),^[2] slightly exceeds Llyn Trawsfynydd in size, but whose height has been slightly raised.