Maentwrog hydro-electric scheme
near Blaenau Ffestiniog.
By 1921 North Wales Power and Traction Co had carried out development work in the mountainous land to the west of the Conway Valley including a power station at Dolgarrog, discharging into the river.[1]
1925 Failure of the Eigiau Dam at Dolgarrog. 11 workers were killed in the disaster. Within 24 hours, the supply to the towns served by the plant had been substituted by a supply from the other power station at Cwm Dyli, near Snowdon. The furnaces of the Aluminium Co were also flooded by the water from the broken dam.
By 1928 a large expenditure had been made by the North Wales Power Co in augmenting the water storage capacity of the natural lakes, linked by a series of tunnels to the new 24 MW capacity power station at Maentwrog which was also linked by overhead transmission lines to the existing generating stations at Dolgarrog and Cwm Dyli.[2]