09/09/2026
A photo of Cruachan Dam on Cruachan Reservoir under construction in the early 1960s. Cruachan was part of the Loch Awe scheme designed by James Williamson & Partners for the North of Scotland Hydro Electric Board. Built between 1959-65, the 440MW reversible pumped storage development was the first large pumped storage installation in Scotland. The massive buttress-type dam is 1037 ft long with a greatest height of 153 ft and a crest at 1315 ft above sea level. Cruachan power station and machine-hall are entirely underground, located in a cavern 300 ft long and 120 ft high, hewn out of the rock of the mountain. Generation of electricity is timed to occur during daytime peak loads on the supply system, using water flowing from the reservoir down to Loch Awe. Reverse pumping from Loch Awe back up to Cruachan Reservoir is carried out mostly at night and at weekends, using surplus energy from generating stations elsewhere. The Loch Awe Scheme comprised three power stations: Inverawe, Nant and Cruachan, the latter two being underground. Inverawe is supplied by a tunnel from Loch Awe and discharges into Loch Etive, whereas Nant is fed from Loch Nant by a tunnel supplemented by an aqueduct collecting from local streams and discharges into Loch Awe. The development of the scheme was a key component of the North of Scotland Hydro Electric Board’s plans to exploit the natural resources of the Highlands to generate electricity.
📸 © Copyright: HES (Records of the North of Scotland Hydro Electric Board (1943-90), Edinburgh, Scotland