Tummel hydro-electric power scheme

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The Tummel hydro-electric power scheme for the generation of hydro-electric power is located in the Grampian Mountains, between Loch Ericht, Loch Rannoch and Loch Tummel, in Perth and Kinross, Scotland.

The Tummel valley is ideally suited to hydro-electric power generation, with heavy rainfall in a catchment area of 1,839 square kilometres. The Grampians, sculpted by glacial action during the last ice age, contain some of the most rugged and remote parts of the Scottish Highlands. There are nine power stations located between Pitlochry in the east, Dalwhinnie in the north and Rannoch Moor to the west. The scheme was constructed between 1930 and 1962 and employs the cascade principle, where the water is used repeatedly as it progresses down river.

In the north, the 2.5 MW Cuaich station in Glen Truim discharges into the largest reservoir in the scheme, Loch Ericht. The 2.2 MW Ericht station is fed from Loch Garry in the mountains above. From here, the water flows down through the 44.1 MW Rannoch station on the northern shore of Loch Rannoch.

In the west is the 7.9 MW Gaur station, the first in Scotland to be automated in 1953, sited on the River Gaur which flows into Loch Rannoch. From Loch Rannoch water flows down to the control centre for the scheme, the 34 MW Tummel Bridge station on Dunalastair Reservoir, and then into Loch Tummel. The 75 MW Errochty station, the largest in the scheme, is fed by tunnel from Loch Errochty to the north which is the location for the small Trinafour station..

Water from Loch Tummel is conveyed by tunnel to the 61.2 MW Clunie station just south of Killiecrankie, at the confluence of the rivers Garry and Tummel, before flowing on to The 15 MW Pitlochry station on Loch Faskally. The loch is retained behind Pitlochry dam and attracts approximately 500,000 visitors annually, due in part to the fish ladder where visitors can watch salmon pass up river to spawn.

The stations forming the Tummel scheme generate a total of 245 MW, and water arriving at Pitlochry may have passed through five power stations en route. The scheme is run by Scottish & Southern Energy plc (previously the privatised Scottish Hydro-Electric), with headquarters in Perth.