Listed Building

The only legal part of the listing under the Planning (Listing Buildings and Conservation Areas) (Scotland) Act 1997 is the address/name of site. Addresses and building names may have changed since the date of listing – see 'About Listed Buildings' below for more information. The further details below the 'Address/Name of Site' are provided for information purposes only.

Address/Name of Site


Status: Designated


There are no additional online documents for this record.


Date Added
Local Authority
Planning Authority
NN 37254 80749
237254, 780749


C S Meik and William Halcrow supervising engineers; Balfour Beatty general engineers, 1934; some later additions. Curved plan gravity dam with continuous arcade of arches (interrupted by valve house to centre) bearing roadway and control towers. Concrete downstream face (W) with coursed bullfaced rubble to arched arcade and parapet. Broad central bay breaking parapet with tall narrow round arched opening and paired rectangular openings above. Central square plan, single storey, single bay coursed rubble control tower to parapet with round headed doorway in west side and multi-pane glazing to windows. Similar, but 2-storey, control tower at south end of dam both housing control valves and gates.

Statement of Special Interest

This dam is located in a very prominent location, adjacent to the A86 road with picturesque backdrop of mountains formed by the Grey Corries. The dam design includes innovative self regulating siphons which manage the water level in the dam without the need for human intervention. The dam also forms part of the Lochaber water power scheme and aluminium smelter, one of the most significant civil engineering schemes of the 20th century in Britain. The dam provides storage capacity for the hydroelectric powerhouse at Lochaber with the water passed through a tunnel (the tower to the S end of the dam contains a control gate for the tunnel) into Loch Treig and then on to the powerhouse via a further tunnel running under Ben Nevis.

The architectural treatment of the dam is a fusion of both plain classical design with a striking modernist form characterised by the sweeping line of the flared dam wall. The striking use of concrete to create dynamic forms clearly illustrates the idea of modernity and progress which characterised the development of hydroelectricity in this period.

The design of the dam includes automatic siphon valves to the upstream face which allow water level to self regulate. The siphons contain a float operated air valves that prime and subsequently break the siphon action at preset reservoir levels.

The Lochaber powerhouse and smelter were part of one of the most significant British engineering achievements of the 20th century. The creation of a pressure tunnel bored through solid bedrock under the flanks of Ben Nevis to connect the powerhouse with the Laggan and Treig reservoirs was a major technological achievement in 1929. The scheme was designed to a very high degree of detail, capturing every available water supply available and was highly efficient.

The development of the Lochaber scheme predates the 1943 Hydroelectric (Scotland) Act which formalised the development of Hydroelectricity in Scotland and led to the founding of the North of Scotland Hydroelectric Board. Those developments which predated the 1943 act were developed by individual companies as a response to particular market and topographic conditions. The completion of a number of schemes (including Galloway, Grampian and those associated with Alcan - see separate listings) without a national strategic policy framework is exceptional as is the consistency of high quality aesthetic and engineering design across all of the schemes.

Sir William Halcrow was one of the foremost engineers of the 20th century, and was highly experienced in the development of hydroelectricity having served his apprenticeship with Thomas Meik and Sons who were responsible for both Kinlochleven and Lochaber water power schemes on behalf of the British Aluminium Company (see separate listings). His work on the Grampian scheme came in between the Kinlochleven and Lochaber developments, and his experience in developing the Kinlochleven scheme can clearly be seen in the highly efficient pioneering nature of the Tummel Garry development. Halcrow's association with hydropower and water engineering was longstanding and after 1943 he went on to work on a number of projects for the North of Scotland Hydro-Electric Board including the Glen Affric and Glen Morriston schemes. The company also completed work elsewhere in the UK and overseas.

(Upgraded B to A as part of Hydroelectric Power Thematic Survey 2010)



Peter Payne, The Hydro: a study of the development of the major hydro-electric schemes undertaken by the North of Scotland Hydro-Electric Board, 1988, pp. 6; Emma Wood, The Hydro Boys, 2002, pp 39; The Lochaber Water Power Scheme; Concrete and Constructional Engineering IV (1909) p.585-587; Alcan, Aluminium in the Scottish Highlands; The British Aluminium Co. Ltd, The Lochaber Water Power Scheme; W. M Morrison, Aluminium and Highland Water Power, Lecture to the Institute of Metals, 1939; Mary Miers, The Western Seaboard, (2008) pp. 45.

About Listed Buildings

Historic Environment Scotland is responsible for designating sites and places at the national level. These designations are Scheduled monuments, Listed buildings, Inventory of gardens and designed landscapes and Inventory of historic battlefields.

We make recommendations to the Scottish Government about historic marine protected areas, and the Scottish Ministers decide whether to designate.

Listing is the process that identifies, designates and provides statutory protection for buildings of special architectural or historic interest as set out in the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997.

We list buildings which are found to be of special architectural or historic interest using the selection guidance published in Designation Policy and Selection Guidance (2019)

Listed building records provide an indication of the special architectural or historic interest of the listed building which has been identified by its statutory address. The description and additional information provided are supplementary and have no legal weight.

These records are not definitive historical accounts or a complete description of the building(s). If part of a building is not described it does not mean it is not listed. The format of the listed building record has changed over time. Earlier records may be brief and some information will not have been recorded.

The legal part of the listing is the address/name of site which is known as the statutory address. Other than the name or address of a listed building, further details are provided for information purposes only. Historic Environment Scotland does not accept any liability for any loss or damage suffered as a consequence of inaccuracies in the information provided. Addresses and building names may have changed since the date of listing. Even if a number or name is missing from a listing address it will still be listed. Listing covers both the exterior and the interior and any object or structure fixed to the building. Listing also applies to buildings or structures not physically attached but which are part of the curtilage (or land) of the listed building as long as they were erected before 1 July 1948.

While Historic Environment Scotland is responsible for designating listed buildings, the planning authority is responsible for determining what is covered by the listing, including what is listed through curtilage. However, for listed buildings designated or for listings amended from 1 October 2015, legal exclusions to the listing may apply.

If part of a building is not listed, it will say that it is excluded in the statutory address and in the statement of special interest in the listed building record. The statement will use the word 'excluding' and quote the relevant section of the 1997 Act. Some earlier listed building records may use the word 'excluding', but if the Act is not quoted, the record has not been revised to reflect subsequent legislation.

Listed building consent is required for changes to a listed building which affect its character as a building of special architectural or historic interest. The relevant planning authority is the point of contact for applications for listed building consent.

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