The lake lies in a glacial valley which follows the Bala to Tal-y-Llyn fault line. The valley was blocked by a terminal moraine in the area of the village of Bala, thus forming the lake, which has remarkably straight and parallel sides.
Origins of name
wrote of the lake in Wild Wales in 1856, "The lake has certainly not its name, which signifies 'Lake of Beauty', for nothing". In English the lake is sometimes named after the nearby town of Bala, whose name means "outlet of a lake" in Welsh. An older, now unused, English name for the lake is Pemble Mere or Pimble Mere. The twelfth century traveller, Giraldus Cambrensis mentions it as Penmelesmere which translator Sir Richard Colt Hoare writing in 1806 records in a footnote also in the form Pymplwy meer or the 'meer of five parishes adjoining the lake'. Hoare goes on to say that it is, in modern days, better known by the name of Bala Pool.
Biology
Llyn Tegid has abundant pike, perch, brown trout, roach, eel. It also contains the gwyniad, a fish unique to the locality and listed as critically endangered by the IUCN due to the introduction of the invasive and non native ruffe; and the very rare mollusc Myxas glutinosa. According to legend, whilst the Dee itself flows through the lake, the waters never mix. However this was not confirmed by the detailed limnological work undertaken from the 1990s, to understand and manage the occurrence of algal blooms on the lake. The lake now forms part of the River Dee regulation system and the level at its outflow is automatically controlled. Depending on flow conditions and the level of water in Llyn Celyn, water can flow either into or out of the lake at the normal outflow point. In the 1990s the lake suffered from blooms of blue-green algae which indicated a significant and worrying eutrophication of the lake. Investigation by the Environment Agency in partnership with the water industry, the farming community and others has put in place a plan for reducing pollution inputs to the lake.
Legend
In the legend of the History of Taliesin, the character Tegid Foel was the husband of the goddess or witch Ceridwen. The place where his court stood is now beneath the waters of the lake. According to folk tradition, the court was drowned one night. It is said that the light of the court and the little town around it can be seen on a moonlit night.
Recreation
Bala has two sailing clubs, and a number of companies provide kayaks, yachts and various other types of boats for hire.
