Yuba County is a county located in north-central Central Valley, California, United States. As of the 2020 U.S. Census, its population was 81,575. Yuba County is included in the Yuba City metropolitan statistical area, which is also included in the Sacramento–Roseville combined statistical area. The county is in the Central Valley region along the Feather Riv…Yuba County is a county located in north-central Central Valley, California, United States. As of the 2020 U.S. Census, its population was 81,575. Yuba County is included in the Yuba City metropolitan statistical area, which is also included in the Sacramento–Roseville combined statistical area. The county is in the Central Valley region along the Feather River; the county seat is Marysville.