Saskatchewan River Delta

53°27′9″N 100°37′28″W / 53.45250°N 100.62444°W / 53.45250; -100.62444

The Saskatchewan River Delta (SRD), also known as Cumberland Marshes, is a large alluvial delta that straddles the border of the provinces of Saskatchewan and Manitoba in Western Canada. Currently terminating at Cedar Lake, Manitoba, the delta is composed mainly of various types of wetlands, shallow lakes, and active and abandoned river channels bordered by forested natural levees. Sixty-five percent of the delta is occupied by vegetated wetlands, over one third of which comprise peat-forming fens and bogs.^[2][3] Geographically, the SRD consists of two parts – western and eastern – separated by a prominent moraine (The Pas Moraine) that was deposited by the Laurentide Ice Sheet during late stages of the Wisconsinan glacial epoch. These two components, commonly termed the "upper delta" and "lower delta", together occupy an area of approximately 10,000 km² (3,900 sq mi) making the SRD one of the largest active inland deltas in North America.^[4] The broad wetland tracts of the upper delta in Saskatchewan are sometimes referred to as the Cumberland Marshes.^[5] Approximately 5% of the delta surface has been drained for agricultural use following feasibility studies by the Prairie Farm Rehabilitation Administration in the 1950s.

The SRD is fed mainly by the Saskatchewan River, whose drainage basin extends westward to the continental divide and includes the eastern slopes of the Canadian Rocky Mountains and much of the high plains region of southern Alberta and Saskatchewan. The Saskatchewan River sensu stricto begins at the confluence of its two main tributaries, the North and South Saskatchewan Rivers, 175 kilometres (109 mi) upstream from the head of the SRD. Approximately 80% of the flow to the delta comes from the Saskatchewan River whereas the other 20% is supplied by smaller streams that enter the SRD at its margins. These include the Torch, Mossy, Grassberry, Sturgeon-Weir, Carrot, and Pasquia Rivers. Most of the SRD is uninhabited, but approximately 15,000 people live in scattered communities around its perimeter, about two-thirds comprising Metis and First Nations peoples and one-third Euro-Canadian. Principal communities, including associated Indian reserves, are The Pas, Moose Lake, and Cormorant (in Manitoba) and Cumberland House, Red Earth, and Shoal Lake (in Saskatchewan). Well over half of the delta population resides in and near The Pas, situated on The Pas Moraine between the upper and lower deltas.