[1] The lake was created between 1924 and 1928 by building four dams in order to supply water for Maentwrog power station.

More than twenty properties, some of historical significance, were lost in the creation of the lake but there was little local objection at the time.

[2] Indeed, the power station was regarded as a good thing because it could supply the whole of North Wales' electricity needs.

In 1965 the lake became the source of cooling water for the Trawsfynydd nuclear power station which began generating electricity for the UK National Grid.

[3] Since the plant's closure, the lake has cooled to natural levels allowing fauna and flora to regenerate.