In the 1950s, Wimpey Construction built the Lairg Dam at the southeast end of the loch. The wall is not large by international standards, but the result on a long, narrow Highland basin was dramatic. The water level rose by more than thirty feet, drowning shoreline farms, old paths, and a band of vegetation that had been there for centuries. The justification was hydroelectric power - part of the great post-war programme led by the North of Scotland Hydro-Electric Board, championed by Tom Johnston as Secretary of State for Scotland during the war, designed to bring electricity to glens that had never had it. By the late 1950s power was flowing south, and the loch had taken on the shape it has today: wider, deeper, and quieter than its original self.

On either side of the loch the land rises into some of the most distinctive mountains of the northwest. To the west is Ben More Assynt, the highest peak in Sutherland at 3,273 feet, sharing a ridge with its twin Conival. The geology beneath their grey screes is Cambrian and Pre-Cambrian rock, some of the oldest exposed strata in Europe. To the east, Ben Klibreck rises to 3,154 feet, a more isolated and rounded mass with a long whaleback ridge. Both are Munros, both attract hillwalkers in summer, and both are deserted most of the year. Standing on the loch shore between them you have a sense of being held in a long corridor of stone, with the water running through it and the wind running over it.

The loch drains through the short, steep River Shin, which falls almost immediately into the gorge above the Falls of Shin. From there the water joins the Kyle of Sutherland at Inveran and flows out into the Dornoch Firth and the North Sea. The whole journey from the head of Loch Shin to the open ocean takes perhaps half a day in spate, less when the dam is running heavily. Atlantic salmon and sea trout make the journey in reverse each summer, climbing the falls and entering the loch system to spawn in the rivers and tributaries that drain into it.

The land around the loch is among the most thinly inhabited in Scotland. Sheep farming is the main agricultural activity, the heirs of the great changes that reshaped Sutherland in the nineteenth century when townships across the strath were cleared and the population moved or scattered. Three miles north of Lairg, on the road that follows the loch's eastern shore, stands a monument commemorating an early attempt by the Sutherland estates to 'improve' the Highlands - the very phrase used at the time for the clearance policies. The monument is a reminder that the apparent emptiness of this country is not natural; it is the result of decisions made in country houses far from here, two centuries ago. The loch reflects the hills, the wind ripples the surface, and the road runs on for many miles before reaching the next village.