This scheme for hydro-electric power generation is centred around Loch Earn, Loch Lyon and Loch Tay, approximately 14 miles (22 km) north northwest of Callander. The area is well suited to hydro-electric power generation, with significant rainfall on high peaks which flows down into deep valleys. The scheme includes seven power stations and was built by the North of Scotland Hydro-Electric Board under the chairmanship of Tom Johnston (1881 - 1965). Although the first section came on-stream in 1956, it was not fully operational until 1961.
Behind Ben Lawers a system of tunnels and aqueducts collects water and diverts it into Lochan-na-Lairige behind a massive buttress-type dam, 344m (1128 feet) long and 42m (138 feet) high. Water descends a vertical distance of 415m (1361 feet; the greatest drop of any Scottish hydro-electric scheme) to Finlarig power station on the shores of Loch Tay.
To the west, the Killin section includes three power stations at Lubreoch, Lochay and Cashlie and involves a main storage reservoir at Loch Lyon retained by another massive buttress dam, 530m (1738 feet) long and 39m (128 feet) high. Water is diverted into Loch Lyon from the Rivers Lochay and Dochart to the south. This section includes fish ladders and lifts to convey salmon to their spawning areas.
Between Loch Tay and Loch Earn is the St. Fillans section, which involves dams at Loch Breaclaich and the man-made Loch Lednock. The latter is a rare British example of a dam designed to cope with earthquake hazards, which are occasionally caused by movement on the nearby Highland Boundary Fault. Water passes through the small Lednock power station on it way into the Loch Lednock Reservoir and then flows down to the 21 MW power station buried in a hillside at St. Fillans. A weir below Loch Earn diverts water into the small Dalchonzie Power Station.
The stations forming this scheme generate a total of 120 MW of power and are run by the privatised Scottish & Southern Energy Plc (previously Scottish Hydro-Electric), headquartered in Perth, which has an annual turnover of £2.3 billion.