Qualla: Loch Sloy Hydro-Electric Scheme

Loch Sloy Hydro-Electric Scheme: Introduction

Sat, 30 May 2026 00:00:00 GMT

Photo credit Scotland_location_map.svg: Eric Gaba, NordNordWest derivative work: Uwe Dedering, CC BY-SA 3.0. Margaret Johnston cut the first sod on 11 June 1945 using an 18-ton bulldozer instead of the traditional polished spade, which seemed about right for the scale of what was beginning. Six weeks earlier the war in Europe had ended. Britain had a power crisis, a labour shortage, and an Act of Parliament authorising the new North of Scotland Hydro-Electric Board to make electricity from rainfall. Loch Sloy was their first project. Over the next five years, in incessant rain, with workers fleeing the cold and inedible camp food, with 398 German prisoners of war hauling cement up the mountain, the Board built a 184-foot buttress dam, drove tunnels through the Arrochar Alps, and installed the largest generator sets in Britain. Twenty-one men died during construction. The plaque in the power station bears their names.

Image: Scotland_location_map.svg: Eric Gaba, NordNordWest derivative work: Uwe Dedering | CC BY-SA 3.0

Loch Sloy Hydro-Electric Scheme: The Engineer With 102 Ideas

Sat, 30 May 2026 00:00:00 GMT

Photo credit James T M Towill, CC BY-SA 2.0. Edward MacColl had been thinking about Loch Sloy since 1936. Working for the Central Electricity Board, he proposed something radical: a pumped-storage scheme that would push water uphill from Loch Lomond into Loch Sloy at night, when demand was low, and let it fall back through ...

Image: James T M Towill | CC BY-SA 2.0

Loch Sloy Hydro-Electric Scheme: Building in the Rain

Sat, 30 May 2026 00:00:00 GMT

Photo credit James T M Towill, CC BY-SA 2.0. The post-war labour shortage hit construction immediately. Within months, 398 German prisoners of war joined 45 British workers on the project. They built access roads, camps, and a railway bridge for the West Highland Line. Aggregate came from a quarry at Coiregrogain, moved by ...

Image: James T M Towill | CC BY-SA 2.0

Loch Sloy Hydro-Electric Scheme: The Buttress Dam

Sat, 30 May 2026 00:00:00 GMT

Photo credit James T M Towill, CC BY-SA 2.0. James Williamson, one of the Board's panel engineers, designed the dam as a buttress rather than a solid gravity wall. The decision saved roughly twenty percent of the concrete that would otherwise have been needed, a serious benefit when cement was being rationed. The completed ...

Image: James T M Towill | CC BY-SA 2.0

Loch Sloy Hydro-Electric Scheme: Catchments, Tunnels, and Five-Minute Standby

Sat, 30 May 2026 00:00:00 GMT

Photo credit James T M Towill, CC BY-SA 2.0. Loch Sloy's natural catchment was too small for the project. The engineers extended it westward and southward by capturing burns that would otherwise have run to Loch Long, Loch Fyne, and Loch Lomond directly. Tunnels and pipelines now thread through the Arrochar Alps from Eas Ri...

Image: James T M Towill | CC BY-SA 2.0