High Quality Content by WIKIPEDIA articles! The Yuba River is a tributary of the Feather River in the Sacramento Valley of the U.S. state of California. It is one of the Feather`s most important branches, providing about a third of its flow. The main stem of the river is about 40 miles (64 km) long, and its headwaters are split into North, Middle and South forks; the confluence of the former two is considered the beginning of the Yuba. The river drains about 1,339 square miles (3,470 km2) of the western slopes of the Sierra Nevada mountain range as well as a small portion of the Sacramento Valley.