The Qu'appelle River Dam is the smaller of two embankment dams: which created Lake Diefenbaker in Saskatchewan, Canada. The larger dam is Gardiner Dam, the biggest embankment dam in Canada and one of the biggest in the world. Construction of both dams began in the 1959 and was completed in 1967. The dam keeps the flow of water in the Qu'Appelle River relatively constant, as the Qu'Appelle river used to dry up in many places every summer when the snow that fills in the South Saskatchewan River from the Rocky Mountains was done melting. This along with Buffalo Pound Dam at Buffalo Pound Lake: which supplies water to Regina, Moose Jaw and The Mosaic Company Potash Mine at Belle Plaine keeps the lake from fluctuating too much. The Canadian Pacific Railway crosses the river atop of the dam. The dam is 3100 metres long and 27 metres high. Douglas Provincial Park (named after former premier of Saskatchewan Tommy Douglas) extends from the dam to Mistusinne.