Lake Diefenbaker is a reservoir lake south of Saskatoon, Sask. It was formed by the construction of 2 dams that created a widening in the South Saskatchewan River as part of the South Saskatchewan River Development Project, inaugurated in 1958. The reservoir has a live storage capacity of about 4 billion m3 of water that feeds a hydroelectric power plant and an irrigation project. It contributes to the water supply of Saskatoon and is a popular water recreation area. It was named in 1967 for John Diefenbaker, the first Saskatchewan resident to become prime minister of Canada; the larger of the 2 dams is named for James G. Gardiner, Diefenbaker's arch-opponent.