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 was built across part of its eastern side to supply water for the power station at Dolgarrog. This power station then provided energy to the adjacent aluminum works. Materials for the dam were transported along the newly laid Eigiau Tramway, which followed the path of the former Cedryn Quarry Tramway.