In 1911 a dam ¾ mile long and  high was built across part of its eastern side to supply water for the power station at Dolgarrog, which in turn provided power for the adjacent aluminium works. Materials for the dam were transported along the newly laid Eigiau Tramway, which ran from Dolgarrog and utilized the route of the former Cedryn Quarry Tramway.
In 1911, a dam ¾ mile long and high was constructed across part of its eastern side to provide water for the power station at Dolgarrog, which then supplied energy to the nearby aluminum works. Materials for the dam were transported along the newly laid Eigiau Tramway, which originated from Dolgarrog and utilized the path of the former Cedryn Quarry Tramway.