This definition appears rarely
0 km) northeast of Oroville in eastern Butte County. In terms of drainage areas the largest is the North Fork, which drains about 60% of the entire upper Feather River watershed. The Middle Fork is the second largest, draining about 32% of the upper basin. The South Fork and the West Branch are much smaller, each drains less than 5% of the upper basin.  The main stem Feather River begins at Oroville Dam, the outlet of Lake Oroville.