Hudson Bay drainage basin

The Hudson Bay drainage basin is the drainage basin in northern North America where surface water empties into the Hudson Bay and adjoining waters. Spanning an area of about 3861400 km2 and with a mean discharge of about 30,900 m³/s, the basin is almost entirely within Canada. It encompasses parts of the Canadian Prairies, Central Canada, and Northern Canada. A small area of the basin is in the northern part of the Midwestern United States. The Hudson Bay drainage basin coincides almost completely with the former territory of Rupert's Land, claimed by the Hudson's Bay Company in the 17th century. It was an ideal area for the early North American fur trade.

Boundaries and limits
The Hudson Bay's connection to the Labrador Sea (the Atlantic Ocean) is at the Hudson Strait's mouth, between Resolution Island in the Qikiqtaaluk Region and Cape Chidley on the Labrador Peninsula. The watershed's headwaters to the south-west are on the Continental Divide of the Americas, bounded at Triple Divide Peak to the south, and Snow Dome to the north. The western and northern boundary of the watershed is the Arctic Divide, and the southern and eastern boundary is the Laurentian Divide.

The basin covers parts of the Canadian provinces and territories of Quebec, Ontario, Manitoba, Saskatchewan, and Alberta, Nunavut, and the Northwest Territories. U.S. states within the basin include Montana, South Dakota, North Dakota, and Minnesota.

Hudson Bay is often considered part of the Arctic Ocean. For example, the International Hydrographic Organization (in its current unapproved working edition only of Limits of Oceans and Seas) defines the Hudson Bay, with its outlet extending from 62.5 to 66.5 degrees north (just a few miles south of the Arctic Circle) as being part of the Arctic Ocean, specifically "Arctic Ocean Subdivision 9.11". Other authorities include it with the Atlantic Ocean, in part because of its greater water budget connection.

Rivers
The largest river system within the Hudson Bay drainage basin is the Nelson River. While the Nelson runs a relatively short 644 km from Lake Winnipeg to the Hudson Bay, its tributaries extent as far west as the Rocky Mountains. From the Hudson Bay to Nelson River's farthest tributary, the Bow River, it has a length of 2575 km and a drainage basin of 1072300 km2. Some significant rivers include the Saskatchewan (550 km), North Saskatchewan (1287 km), South Saskatchewan (1392 km), Red (880 km), Assiniboine (1070 km), and the Red Deer (740 km).

The following list of rivers includes the principal rivers draining into the Hudson, James, and Ungava Bays of the Hudson Bay drainage basin. The rivers are presented by coastline, clockwise, starting with the George River in north-eastern Quebec, just south of Cape Chidley and the entrance to the Atlantic Ocean.

George
 * Rivers of Quebec

Whale

False

Koksoak

Leaf

Arnaud

Kovik

Povungnituk

Kogaluc

Innuksuac

Qikirtaluup Kuunga

Nastapoka

Little Whale

Great Whale

Roggan

La Grande

Eastmain

Pontax

Rupert

Broadback

Nottaway

Harricana

Moose
 * Rivers of Ontario

Albany

Lawashi

Attawapiskat

Ekwan

Winisk

Severn

Hayes
 * Rivers of Manitoba

Nelson

Churchill

South Knife

North Knife

Seal

Caribou

Geillini
 * Rivers of Nunavut

Thlewiaza

Tha-anne

Ferguson

Wilson

Thelon

Lorillard

Brown

Kirchoffer (Southampton Island)

Koukdjuak (Baffin Island)