In the beginning: the legend of Ben Cruachan

Legend has it there was once a fountain that welled up from the peak of Ben Cruachan, guarded by the Cailleach Bheur, or Old Hag of the Ridges.

Her duty was to cover the spring with a slab of stone at sundown and lift away the rock at dawn. One evening she fell asleep and the well overflowed, rushing down the mountainside and bursting open a new outlet to the sea through the Pass of Brander.

Legend says this is how the River Awe and Loch Awe were formed. The Cailleach was turned to stone as punishment for her negligence and to this day sits above the Pass of Brander.


Conceiving the Hollow Mountain

Cruachan was the brainchild of Sir Edward McColl, a Dumbarton-born engineer and pioneer of hydro power in Scotland.

Having started his career at the Glasgow Corporation and Clyde Valley Electric Power Company, McColl turned his attention to bringing hydroelectricity to the Highlands and conceived the idea for Cruachan Power Station in the 1930s.

Ben Cruachan mountain


Tom Johnston pushes Cruachan through parliament

Tom Johnston, a native of Kirkintilloch and wartime Secretary of State for Scotland, was a huge advocate of hydroelectric power in the region. When he came across the scheme for the Hollow Mountain he forced it through Parliament in 1947.

Visitors in the control room


Design begins

The designer of Cruachan was James Williamson, a civil engineer from Lanarkshire. A lot of time was spent at the design stage, optimising all aspects of construction and operation. Many working models of the turbines were built and work tests were carried out on completed alternators before being delivered to the site.

Cruachan dam construction
Cruachan dam construction


The Tunnel Tigers get to work

During the six years of construction, there was a large workforce of 1,300 men, affectionately known as the Tunnel Tigers. But before they could build the power station inside the mountain, they had to drill and blast into it. The men used handheld air drills to bore holes in the solid granite rock, which were then packed with gelignite and blasted.

Because of the limitations of local roads and the size of the access tunnel, all the equipment had to be broken down into manageable loads for transportation. The first plant items to be installed were the turbine casings, which were mounted at the lower levels of the cavern.

Cruachan construction - the Tunnel Tigers


Connecting Cruachan

A 275,000V transmission line was constructed to carry power from the top of the cable shaft just in front of the dam to Dalmally substation, five miles east of Cruachan, and then on to Windyhill, north of Glasgow. This line remains in place today, passing through rough terrain and reaching 550 metres above sea level at its highest point.

Cruachan machinery
Cruachan substation transformer


The Royal Opening

Cruachan Power Station was officially opened by Her Majesty The Queen on 15 October 1965. It was the first reversible pumped storage hydro system on this scale to be built in the world.

Queen Elizabeth opening Cruachan


Reaching full load

At the time The Queen officially opened the power station just two of the turbines were completed and operational. It was with the two remaining turbines coming into service in 1966 and 1967 that the Cruachan Power Station reached its full capacity.

Transformer at Cruachan

Cruachan Mural

Inside the machine hall visitors can find a mural of inlaid woods by artist Elizabeth Falconer which depicts the history of Cruachan, from its legendary origins to its role in power generation today.