North Fork Feather River

The North Fork Feather River is a watercourse of the northern Sierra Nevada in the U.S. state of California. It flows generally southwards from its headwaters near Lassen Peak to Lake Oroville, a reservoir formed by Oroville Dam in the foothills of the Sierra, where it runs into the Feather River. The river drains about 2,100 square miles (5,400 km2) of the western slope of the Sierras. By discharge, it is the largest tributary of the Feather.

It rises at the confluence of Rice Creek and a smaller unnamed stream in the southern part of the Lassen Volcanic National Park. The river flows east, receiving Warner Creek from the left, and passes the town of Chester. It then empties into Lake Almanor, which is formed by the Canyon Dam. After leaving the dam the river cuts south into a gorge, and turns southwest to receive Butt Creek from the right. The East Branch North Fork Feather River, the North Fork's largest tributary, comes in from the left near Belden, where the river is impounded again at the Rock Creek Dam. It then flows southwards into the north arm of Lake Oroville.

The fork's portion of the Feather River Canyon is notable as part of the Feather River Route, and the railroad's North Fork Bridge near the river's mouth is the longest reinforced concrete bridge in the US. Reservoirs on the North Fork include those of the 1962 Rock Creek-Cresta Hydroelectric Project.