The dam, lake and associated waterworks were designed by and built, from 1711 to 1712, by English civil engineer George Sorocold. Sorocold caused the construction of a weir on the Black Devon waterway at Forestmill, raising its waters by , and a lade to carry water about westward to Gartmorn, where it was impounded by an earth dike. The lake formed has a surface of about , reaches a maximum depth of deep, and it situated about above the level of the River Forth, and above Alloa. It is considered the earliest constructed reservoir in Scotland, and was for many years the largest artificial lake in Scotland.
