An expansion of the River Dee, Tongland Loch is a narrow body of water at least 2½ miles (4 km) in length. Retained at its southern end by the Tongland Dam, a concrete arch dam, the loch forms a reservoir for the Tongland Power Station, part of the Galloway Hydro Electric Scheme, located a half-mile (1 km) to the southwest. It opened in 1935.
The importance of the Dee as a salmon river was always a concern when the Hydro Scheme was being built, and a fish ladder was installed to allow the fish to climb over the dam by passing through a staircase comprising 29 pools.
