Plumas County is a county located in the Sierra Nevada of the U.S. state of California. The county gets its name from the Spanish words for the Feather River (Río de las Plumas), which flows through the county. As of the 2010 census, the population 20,007, down from 20,824 at the 2000 census. The county seat is Quincy.
The only incorporated city in the county is Portola, several other populated places are CDPs.