Laggan Dam is a dam located on the River Spean south west of Loch Laggan in the Scottish Highlands. The dam is 700 feet (213 metres) long and rises 170 feet (52 metres) above its foundations, and is part of the Lochaber hydro-electric scheme. The structure was built by Balfour Beatty for the British Aluminium Company and construction was finished in 1934.
Water from the dam is conveyed to Loch Treig through 3 miles (4.8 km) of tunnel. From there, the waters are conveyed to a power house at Fort William via 15 feet (4.6 metre) diameter pipe 15 miles (24 km) long. The dam can be found next to the A86 road from Fort William. The catchment area of the dam was increased by an aqueduct which can be seen at the side of the road in Strath Mashie.