The Assiniboine River (; ) is a 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, Souris and Whitesand 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." Course The Assiniboine River rises in eastern Saskatchewan east of the community of Kelvington on the upper prairie level above the Manitoba Escarpment. The Assiniboine River flows through three basic zones with different channel characteristics. Upstream of Brandon, the main stem of the river and its most important tributaries flow within a very large valley. The valley was cut by huge glacial melt water flows at the end of the last glaciation. The floor of this spillway valley provides a natural floodplain for the river and the valley provides a significant storage volume making the construction of the Shellmouth Dam north of Russell both technically and economically viable. The major tributaries in this reach are the Qu'Appelle, Shell and Little Saskatchewan Rivers. The glacial flows created a large delta east of Brandon extending almost to Portage la Prairie. The river has eroded down through sediments of the delta cutting a narrow valley through these sediments as it drops through a vertical distance of about to the Lake Agassiz – Red River Plain . In this valley, the river is confined with a narrow valley floor. The Souris River is the primary tributary contributing flow to the Assiniboine in this reach. Near Portage la Prairie the river emerges from the delta reach onto the relatively flat Red River plain (the floor of former Glacial Lake Agassiz) and at this point it can flow in any direction