Some say it will take a month to fill, others two months. But since lunchtime yesterday the peaty waters of the River Tarff and a host of other rivers and burns have been rising behind the new multi-million pound dam high in the hills above Fort Augustus at the south-western end of Loch Ness.
Some say it will take a month to fill, others two months. But since lunchtime yesterday the peaty waters of the River Tarff and a host of other rivers and burns have been rising behind the new multi-million pound dam high in the hills above Fort Augustus at the south-western end of Loch Ness.
This means that Scottish and Southern Energy's £150m Glendoe hydro-electric project is nearing its operational phase when it will be capable of generating 100mw of power, sufficient to power Glasgow.
It's a far cry in scale from the efforts of the monks of St Benedict's Abbey in nearby Fort Augustus, who in 1890 constructed an 18-kilowatt water turbine on one of the local streams to supply the abbey and the village. The scale may be bigger, but the basic resource remains the same.
Yesterday the rain was again doing its bit to build up the required 12.7 million cubic metres of water when Alex Salmond appeared on the scene. His mission was to "plug the dam", or more accurately push the button to close the sluice gates. Having done so, the water began turning back on itself, edging back up the pipe towards the rough terrain behind the dam.
The creation of a reservoir with a surface area of two square kilometres had started. A ruined shieling, and great swathes of heather, peat and boulders will soon be submerged with only the herds of red deer suffering obvious loss of amenity. Only the enthusiastic walker and the airborne will see the new expanse of water or the dam retaining it.
The colossal new structure will provide the mass of water required to pour down eight kilometres to an underground power station before being discharged into Loch Ness itself, 600m below.
The plant should be fully operational by Christmas and is scheduled to be supplying electricity into the grid in early 2009. At full production it will generate enough green energy to power more than six million low-energy light bulbs. It will be the second largest hydro project out of the 80 already installed across Scotland.
Most were built in the late 1940s and early 1950s under the direction of Tom Johnston, the war-time secretary of state for Scotland who later became chairman of the North of Scotland Hydro-electric Board, which he was instrumental in setting up. They were built in the face of stiff opposition, particularly from landowners. But the "hydro boys" rampaged across rural Scotland leaving a folkore and mythology in their wake as well as their giant concrete memorials. One thousand or so of their successors did the same at Glendoe over the past two years, although it was no longer Irishmen who were working in the tunnels, but Slovakians.
There was also another difference, a 220m boring machine nicknamed Eliza Jane by local schoolchildren, which finished digging out underground tunnels.
But it is not only the construction techniques that have changed. Now the economics of the electricity industry dictate that even a new scheme such as Glendoe will only provide power at peak times. During the night it is the base load suppliers - the nuclear, coal, and oil power stations - which can't simply throw the off-switch, which are left meeting our needs. However, if one of them breaks down they are normally keen to buy hydro-power rather than incur penalties for loss of supply.
Mr Salmond, who has always had an enthusiasm for hydro-power, could not hide his satisfaction yesterday and thought the industry was about to enjoy a new lease of life. He said: "I think hydro is back, and it is back in a big way. Glendoe heralds more a pointer to the future rather than the close of a chapter.
"I am certain there is substantially more potential for hydro in Scotland and I am certain we will get there. The scale of it will depend on a variety of figures. There are potentially other big projects, but there are also medium-sized projects as well and I would be looking at a significant expansion of hydro-power from where we are just now."
He added: "Scottish and Southern Energy's Glendoe scheme is the first large-scale hydro-electric station to be built in Scotland for 50 years. This is one of the projects which will ensure Scotland's long tradition of generating hydro-power continues for many years to come.
"I am delighted to be involved in marking this major milestone in this ambitious project, which will utilise Scotland's natural resources for the creation of clean, renewable energy.
"The Scottish Government has set an ambitious target to generate 50% of our electricity demand from renewable sources by 2020. The total renewables capacity installed, consented and under construction in Scotland is now over 4.5 GW - we are now less than 500 MW short of our 5 GW target by 2011."
He said Scotland had been the first country to recognise the importance of hydro-energy and to use the water around us to create electricity.
He said: "Today hydro-energy continues to be an important source of power, but if we are to achieve our ambition of making Scotland the green energy capital of Europe we must realise the potential of our huge untapped water resources."
Meanwhile, Iain Marchant, chief executive of SSE, said his company was already the UK's leading generator of renewable energy and planned to invest a further £3bn in renewable projects over the next five years.
He said: "Much of this investment will be made in Scotland. SSE's commitment to renewable energy is not just about tackling climate change, it is about delivering security of energy supply."
