Following the launch of trove.scot in February 2025 we are now planning the retiral of some of our webservices. Canmore will be switched off on 24th June 2025. Information about the closure can be found on the HES website: Retiral of HES web services | Historic Environment Scotland
Field Visit
Date 2010
Event ID 881923
Category Recording
Type Field Visit
Permalink http://canmore.org.uk/event/881923
Laggan Dam is a large concrete gravity dam some 700 feet long and over 130 feet high. The dam increased the length of the loch without adding to its height. It provides storage for the Lochaber scheme, and feeds into Loch Treig (see separate record) via a tunnel at the south end of the dam. The dam contains innovative self regulating siphon valves which use a ball-cock and air filled chamber to automatically start the siphon when the water level reaches a certain height. This is a major dam in the Lochaber scheme, with a significant degree of design interest in the arched arcade which carries the roadway across the top. The landscape contribution of the dam is also significant, set at the top of a steep glen and directly adjacent to a busy A road. The dam also exhibits technical interest with automatic regulation provided by the siphon valves which start the siphons when the water level reaches a predefined height. J R Hume, 1977; P L Payne,1988; E Wood, 2002; Concrete and Constructional Engineering IV (1909); Alcan, ; The British Aluminium Co. Ltd, 1930; Paxton and Shipway, 2007.
