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 Ocean on 14 July 1789. The river he named "Disappointment River" would later be renamed in his honor. No European reached its mouth again until Sir John Franklin on 16 August 1825. The following year he traced the coast west until blocked by ice while John Richardson followed the coast east to the Coppermine River. In 1849 William Pullen reached the Mackenzie from the Bering Strait. In the following decades the North West Company established forts on the river, the precursors of present-day settlements such as Fort Simpson (formerly Fort of the Forks). A lucrative fur trade was carried out,