The Nechako River arises on the Nechako plateau east of the Coast Range of British Columbia and flows north toward Fort Fraser, then east to Prince George where it enters the Fraser River. Its main tributaries are the Stuart River, which enters about east of Vanderhoof; the Chilako, which enters about west of Prince George; and the Nautley River.
The Nechako is one of the main tributaries of the Fraser River, although most of its flow has been diverted through the Coast Mountains to the Kemano generating station at sea level on the Gardner Canal, below the reservoir's intakes, which supplies power to the aluminum smelter at nearby Kitimat. The main reservoir of the Nechako power diversion is named Ootsa Lake Reservoir, but there are many subnames for different parts of the lake as its conversion into a reservoir involved the amalgamation of chains of lakes, the largest of which were Eutsuk Lake and Natalkuz Lake.
The damming of the Nechako in 1952 and the consequent massive reduction in flow has been the source of considerable political controversy. The Cheslatta people (a subgroup of the Dakelh or Carrier) were flooded out by the creation of the reservoir and forced to abandon their homes with only two weeks' warning. The increase in water temperature caused by the reduction in flow has been an ongoing problem for the salmon run.
The expedition of Alexander MacKenzie went past the mouth of the Nechako in 1793, curiously, without observing it. The first European to ascend the Nechako was James McDougall, a member of Simon Fraser's expedition, in 1806.
"Nechako" is an anglicization of [netʃa koh], its name in the indigenous Carrier language which means "big river".