Moraga (incorporating the former communities of Moraga Town, Rheem, and Rheem Valley) is a suburban incorporated town located in Contra Costa County, California, United States, in the San Francisco Bay Area. It is named in honor of Joaquin Moraga, whose grandfather was José Joaquin Moraga, second in command to Juan Bautista de Anza. As of 2010, Moraga had a total population of 16,016people.