Red River drainage basin, with the Assiniboine River highlighted
|Mouth||Red River of the North
|Basin countries||Canada & USA|
|Length||1,070 kilometres (660 mi)|
|Source elevation||640 m (2,100 ft)|
|Mouth elevation||230 m (750 ft)|
|Avg. discharge||45 cubic metres per second (1,600 cu ft/s)|
|Basin area||182,000 km2 (70,000 sq mi)|
The Assiniboine River is a 1,070-kilometre (660 mi) river that runs through the prairies of Western Canada in Saskatchewan and Manitoba. It is a tributary of the Red River. The Assiniboine is a typical meandering river with a single main channel embanked within a flat, shallow valley in some places and a steep valley in others. Its main tributaries are the Qu'Appelle and Souris Rivers. For early history and exploration see Assiniboine River fur trade.
The river takes its name from the Assiniboine First Nation. Robert Douglas of the Geographical Board of Canada (1933) made several comments as to its origin: "The name commemorates the Assiniboine natives called by La Vérendrye in 1730 'Assiniboils' and by Governor Knight in 1715 of the Hudson's Bay Company 'stone Indians.' Assiniboine is the name of an Indian tribe and is derived from 'assine' a stone and 'bwan' native name of the Sioux, hence Stony Sioux name was possibly given because they used heated stones in cooking their food."
Tributaries include the Whitesand River which joins it near Kamsack, Saskatchewan, the Souris River which joins it near Wawanesa, the Birdtail River which joins at the Birdtail Sioux First Nation, the Little Saskatchewan which joins west of Brandon and the Qu'Appelle River which joins near the site of historic Fort Ellice.
Flow rates and flood potential 
There are three hydrometric stations on the river that have been taking measurements since 1913. The Assiniboine River near Headingley has an average discharge of 45m3/s. One millimeter of runoff from half the watershed would take 70 hours to drain at flow rates of 360 m3/s. The following discharge rates were recorded during the 1995 flood:
|Location||Peak flow, 1995
|Mean flow, April '95
|Mean flow, May '95
|Max flow, date
April 29, 1922
May 7, 1923
April 27, 1916
It is prone to spring flooding. Some flood flows can be diverted into Lake Manitoba at Portage la Prairie. In 1967, the Shellmouth Dam was built in Shellmouth to help reduce flood peaks and to supplement flows during dry periods. The Portage Diversion was completed in 1970. Despite these efforts, in May 2011 it was necessary to breech one of the dikes beside the river to relieve flood stresses east of Portage la Prairie. A Manitoba-wide state of emergency was declared in the wake of one in three hundred-year floods on the Assiniboine River at Brandon.
See also 
- Atlas of Canada. "Rivers of Canada". Archived from the original on 24 February 2008. Retrieved 2008-02-15.
- R. Douglas, Place names of Manitoba, Geographic Board of Canada, Department of Interior, Canada, 1933
- Natural Resources Canada. "The Assiniboine River bursts its banks". Archived from the original on 3 February 2008. Retrieved 2008-02-15.
- (The Canadian Press)
- (CJOB 68)