Maentwrog Hydroelectric Power Station
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The land on which the Maentwrog Hydroelectric Power Station, the lake and dam necessary to supply water to it, was purchased in the 1920s by the North Wales Power Company. Construction work began in 1925 and the station was opened on 15 October 1928. When first operated Maentwrog’s output far exceeded the highest demand for electricity in North Wales.
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 North 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.
In 1988 construction began on a replacement dam just 75 metres downstream of the original. Excavation of the foundations took just over a year followed by the pouring of 54,500 cubic metres of concrete to form a new 219m long and 38.8m high S-shaped dam.
Maentwrog’s new dam is at the head of the Ceunant Llennyrch Gorge. The area is part of the Snowdonia National Park and designated a Site of Special Scientific Interest due to the large number of rare species of Atlantic bryophyte flora to be found in the gorge.
During construction work in the late 80s every effort was made to minimise the effect on this special environment. Today the station’s ongoing commitment is to generate energy safely, competitively and with care for the environment.
Maentwrog
