The Yuba River is a tributary of the Feather River in the Sierra Nevada and eastern Sacramento Valley, in the U.S. state of California. The main stem of the river is about 40 miles long, and its headwaters are split into three major forks. The Yuba River proper is formed at the North Yuba and Middle Yuba rivers' confluence, with the South Yuba joining a short di…The Yuba River is a tributary of the Feather River in the Sierra Nevada and eastern Sacramento Valley, in the U.S. state of California. The main stem of the river is about 40 miles long, and its headwaters are split into three major forks. The Yuba River proper is formed at the North Yuba and Middle Yuba rivers' confluence, with the South Yuba joining a short distance downstream. Measured to the head of the North Yuba River, the Yuba River is just over 100 miles long.