This is a 400ft long rock filled dam, damming the River Treig at north end of Loch Treig . It was built to convert the loch into a reservoir, providing a water supply for the hydroelectric scheme opened with the Lochaber Aluminium Works. The water level was raised by 36ft.
The water runs downhill in a tunnel some 15 miles long which drops 72ft along its length before reaching the penstocks of the power station of the smelter at Fort William.
The dam crosses the original route of the West Highland Railway and the water level normally covers part of its former course. Just over a mile of the line was diverted to higher ground - Loch Treig Deviation (London and North Eastern Railway).
Fort William [1st]
| Bridge 1|
Loch Treig Tunnel
Fersit Speeder Shed
Loch Treig Valve Shafts
Loch Treig Speeder Shed
Fersit Cement Shed
Fersit Fitting Shop
|Location names in dark blue are on the same original line.|