The Sweetwater River is a 55-mile (89 km) long stream in San Diego County, California. From its headwaters high in the Cuyamaca Mountains, the river flows generally southwest, first through rugged hinterlands but then into the urban areas surrounding its mouth at San Diego Bay. Its drainage basin covers more than 230 square miles (600 km2), all of it within San Diego County. Towns on the river include Descanso, La Presa and Chula Vista.