The Rheidol hydro-electric scheme covers 160sq km and includes three power stations, three reservoirs, a sub-station and fish weir. Constructed between 1957 and 1961, the scheme produced 53 megawatts (56 megawatts by 1997). The 5,700 million gallon Nant-y-moch Reservoir (nprn 268169) with normal water level at 1113ft OD is impounded by a reinforced concrete dam 1150ft long and 172ft high. From here the water drops 278ft to the smaller Dinas Reservoir (nprn 308001) then via the main turbines at Cwm Rheidol (nprn 91558) to discharge through a small regulating reservoir (nprn 33626) to the river at about 150ft OD.
SN 6978 7959 is the National Grid Reference of the Visitor Centre in Cwm Rheidol.
(Sources: Powergen plc; A Guide to the Industrial Archaeology of Mid-Wales, Association for Industrial Archaeology, 1984)
B.A.Malaws, RCAHMW, 17 November 2011.