A reservoir in S Highland Council Area, the Blackwater Reservoir lies to the north of Rannoch Moor and east of Kinlochleven. It extends 8 miles (13 km) east-west and is drained by the River Leven into Loch Leven. It is fed by a number of streams, the most significant of which are the Black Water and the Ciaran Water.
The reservoir was constructed between 1905 and 1909 to provide water for a hydro-electric scheme which powered the former aluminium smelter at Kinlochleven. The power is now used by another smelter at Fort William.
The Blackwater Dam, at 914m (3000 feet) in length and 27.4m (90 feet) in height, was the largest in Europe of its day. It was also the last major construction project in Scotland to be built without the aid of machinery, but requiring the hard-labour of more than 3000 navvies. A small graveyard which lies just below the dam provides the last resting place for workers who died during the construction.