The watersheds of the North and South Saskatchewan Rivers reflect an array of prairie rivers. In the south, they come from seven small rivers flowing from the Great Divide in both Montana and southern Alberta. These southern rivers merge between the cities of Lethbridge and Medicine Hat, and the South Saskatchewan River first appears (at an elevation of 740 meters) at the confluence (north of Grassy Lake, Alberta). The Red Deer River is also a major tributary of the South Saskatchewan River, merging 16 kilometers east of the Alberta-Saskatchewan border.
After cutting its way through Alberta prairie grasslands, the South Saskatchewan River flows east past Medicine Hat, receiving some tributary flow from small streams rising on the slopes of the Cypress Hills, then flows northeast into Saskatchewan, and continues a course roughly parallel to the North Saskatchewan River to the confluence of the two rivers, located at at Saskatchewan River Forks, some 130 km downstream.
The South Saskatchewan has been dammed about 100 km south of Saskatoon, creating a long broad reservoir, called Lake Diefenbaker, which provides hydroelectric power and irrigation for southwestern Saskatchewan. At Lake Diefenbaker, there is a diversion, that ultimately flows east into the Qu’Appelle River (considered one of the Great Canadian Rivers).
From the confluence of the North and South Saskatchewan Rivers, the river continues nearly 600 km eastward through Tobin Lake and Cumberland Lake, and into Manitoba, where it trends southeast past The Pas and into Cedar Lake. The waters of the Saskatchewan River enter Lake Winnipeg at Grand Rapids, and are then carried to the Hudson Bay by the Nelson River.
From the headwaters, the South Saskatchewan River flows for 1,392 kilometers. At its mouth (Saskatchewan River Forks), it has an average discharge of 280 cubic meters per second. It has has a watershed of about 146,100 km², 1,800 of which are in Montana, and 144,300 km² in Alberta and Saskatchewan.
Located in the steppe region known as Palliser’s Triangle, it has a semi-arid, continental climate (Köppen climate classification BSk), with cold, dry winters and warm to hot summers. However, the winter cold is occasionally ameliorated by mild and dry chinook winds blowing from the west, and hot summer daytime temperatures are made more tolerable by low humidity and rapid cooling in the evening hours. The region receives less precipitation annually than many other locations on the Canadian Prairies and plentiful sunshine (Medicine Hat is widely known as “The sunniest city in Canada”). Maximum precipitation typically occurs in the late spring and early summer.
Located in the region is Cypress Hills, Canada’s first interprovincial park, and the highest point in Canada between the Rocky Mountains and Labrador (maximum elevation – 1,466 metres above sea level). The Cypress Hills are unique in that they were not glaciated during the last ice age; the park’s montane environment is an oasis of mixed lodgepole pine forests in the midst of the Canadian prairies.
Read more… about the Alberta and Saskatchewan portions of the South Saskatchewan River (Partners FOR the Saskatchewan River Basin)