Dolgarrog Hydro Site
UK hydro sites in operation
Dolgarrog is situated 6 miles south of the town of Conwy on the edge of the Snowdonia National Park.
The original construction of a hydroelectric scheme at Dolgarrog was carried out in 1907 by the Aluminium Corporation to provide power for smelting aluminium in the Conwy Valley.
A dam was built to raise the level of Lake Eigiau by 6 metres from where it flowed to the edge of the valley overlooking the village more than 300 metres below. From there, a single steel pipeline delivered the water to the power station, on the same site as the aluminium works.
Further modifications were carried out over the years and now Dolgarrog has two separate systems, each served by separate catchment areas.
Cowlyd reservoir provides water for Dolgarrog's "high head" scheme (17MW total output) via a 5km pipeline utilising a total catchment area of about 44 square kilometres.
Coedty reservoir provides water for Dolgarrog's "low head" scheme (15MW total output) via a 3km pipeline with a catchment area of around 27 square kilometres.