The Qu'appelle River Dam is the smaller of two embankment dams along the South Saskatchewan River that created Lake Diefenbaker in the Canadian province of Saskatchewan. The bigger of the two dams is Gardiner Dam, which is the largest embankment dam in Canada and one of the largest in the world. Construction of both dams began in 1959 and was completed in 1967. Lake Diefenbaker is the largest lake in southern Saskatchewan.