The story
Llyn Cowlyd had been a reservoir since 1908, owned by the Conwy and Colwyn Bay Joint Water Supply Board. By 1915 rights to water extraction were also held by the Aluminium Corporation and the North Wales Power and Traction Co. Ltd., both of Dolgarrog, and a severe drought in this year prompted the decision to increase water reserves by building a much higher dam.
Construction of the Cowlyd Tramway began in 1916, and reached Llyn Cowlyd the following year. The dam was completed in December 1921, being built entirely from rock quarried from the adjacent mountainside, and was opened the following year in more favourable weather.
The tramway was essentially a branch line of the former Eigiau Tramway, built originally as a standard gauge tramway to serve Llyn Eigiau, and connected to the works at Dolgarrog by a series of rope-worked inclines which ran down the steep Dolgarrog escarpment.
The Eigiau Tramway was itself a successor to the narrow gauge Cedryn Quarry Tramway. At the time of the construction of the Cowlyd Tramway the Eigiau Tramway was re-gauged to the same narrow gauge so that the same locomotives could be used on both. After the collapse of the Eigiau dam in 1925, and the closure of that tramway, the inclines were only used by the Cowlyd Tramway.
From Wikipedia’s article on Cowlyd Tramway, shared under CC BY-SA 4.0.3