Location in the UK : Wales, Trawsfynydd reservoir , Gwynedd Type of installation: Hydro on/offshore: on Turbines :4 Capacity : 33 MW Approx Date of 1st power generation:
It originally had an 18 megawatt output from three turbines but a fourth was added in 1934, increasing its output to 24 megawatts. It was replanted in 1991 further increasing capacity to 30 megawatts, and is currently operated by Magnox Limited Ltd.
Trawsfynydd reservoir was formed by the construction of four dams. The principal dam, built cross the Afon Prysor (at the northern end of the lake), was the first large arch dam ever built in Britain. The lake covered an area of two square miles and contains over 33 million cubic metres of water.