Marysville is the county seat of Yuba County, California, United States. As of the 2010 United States Census, the population was 12,072, reflecting a decrease of 196 from the 12,268 counted in the 2000 Census. It is included in the Yuba City Metropolitan Statistical Area, often referred to as the Yuba-Sutter Area after the two counties, Yuba and Sutter. The metropolitan statistical area is part of the Greater Sacramento area.