The South Saskatchewan River is a major river in the Canadian provinces of Alberta and Saskatchewan. The river begins at the confluence of the Bow and Oldman Rivers in southern Alberta and ends at the Saskatchewan River Forks in central Saskatchewan. The Saskatchewan River Forks is the confluence of the South and North Saskatchewan Rivers and is the beginning of the Saskatchewan River.
For the first half of the 20th century, the South Saskatchewan would completely freeze over during winter, creating spectacular ice breaks and dangerous conditions in Saskatoon, Medicine Hat, and elsewhere. At least one bridge in Saskatoon was destroyed by ice carried by the river. The construction of the Gardiner Dam in the 1960s, however, lessened the power of the river by diverting a substantial portion of the South Saskatchewan's natural flow into the Qu'Appelle River. By the 1980s many permanent sandbars had formed due to the lowering of the level of the river.
From the headwaters of the Bow River, the South Saskatchewan flows for 1,392 kilometres (865 mi). At its mouth at Saskatchewan River Forks, it has an average discharge of 280 cubic metres per second (9,900 cu ft/s) and has a watershed of 146,100 square kilometres (56,400 sq mi), 1,800 of which are in Montana in the United States and 144,300 square kilometres (55,700 sq mi) in Alberta and Saskatchewan.

Quelle: Wikipedia