Spring Valley. 1 Uninc. community (1990 pop. 55,331), within the confines of San Diego, San Diego co., SW Calif., on Sweetwater Lake. It is a rapidly growing residential community, with some light industrial production (transportation equipment and paper and metal products). The Bancroft Ranch House Museum (1856) is a national historic landmark. 2 Residential village (1990 pop. 21,802), Rockland co., SE N.Y., near the N.J. line; inc. 1902. It is a fast-growing suburb with office complexes and shopping malls.