Hay River (Canada) border, the annual discharge is . Hay River (Canada) The Hay River (in South Slavey: "Kátå’odehche") is a large river in northern Alberta and southern Northwest Territories, Canada. It originates in the muskeg of north western Alberta, flows west to British Columbia, then curves northward and returns to Alberta, where it follows a north-northeast course towards the Northwest Territories. After passing over two main waterfalls, the Alexandra Falls and Louise Falls, it flows through the town of Hay River and discharges into the Great Slave Lake. From there, its waters are carried to the Arctic Ocean by the Mackenzie River.
Mackenzie River watershed drains about 20 percent of Canada. It is the largest river flowing into the Arctic from North America, and including its tributaries has a total length of , making it the thirteenth longest river system in the world. Through its many tributaries, the Mackenzie River basin covers portions of five Canadian provinces and territories – British Columbia (BC), Alberta, Saskatchewan, Yukon, and Northwest Territories. Thutade Lake, in the Northern Interior of BC, is the ultimate source of the Mackenzie River via the Finlay–Peace River system, which stretches through BC and Alberta. The Athabasca River originates further south, in Jasper