The structure was built as part of the Lochaber hydroelectric scheme by Balfour Beatty for the British Aluminium Company and construction was finished in 1934.

[1][2] The dam is about 700 feet (210 metres) long,[3] and 48 m (157 ft) high between the level of the foundations and the crest of the spillway.

[4] As well as the spillway, there are six self-priming siphons embedded into the centre of the dam, controlled automatically by system of air valves.

From there, the waters travel through a further 15 miles (24 kilometres) of tunnel, 15 feet (4.6 metres) in diameter, before descending the hillside to a power house at Fort William through five steel pipes.

Between 1941 and 1943, the catchment was further expanded by constructing another dam across the headwaters of the River Spey, and diverting flow through a tunnel to Loch Laggan.