Churchill River, Labrador, 856 km long (to head of Ashuanipi River), issues from Ashuanipi Lake, drops 75 m over Churchill Falls, broadens into Winokapau Lake and runs east through a deep glacial gorge past Happy Valley-Goose Bay into Lake Melville, Hamilton Inlet, entering the Atlantic near Rigolet (pop 317). It is the longest river in Labrador and has a drainage basin of 79 800 km2 and a mean discharge of 1620 m3/s. The power development at Churchill Falls has backed up the river and created the enormous Smallwood Reservoir. Farther upstream, a hydroelectric plant at the outfall from Menihek Lakes provides power for the former iron-mining town of Schefferville, Québec. With a heavy flow and large drop from the Labrador Plateau, the river has probably the greatest hydroelectric potential of any in North America. Fort Smith (now North West River) was an early HBC post at its mouth. John McLean first reached the river from the interior 1839. It was named for Sir Charles Hamilton, governor of Newfoundland in 1821, but Premier Joseph Smallwood renamed it in honour of Sir Winston Churchill (1965). The change has caused confusion since Canada already had a Churchill River (in Manitoba and Saskatchewan).