http://www2.census.gov/geo/maps/dc10map/GUBlock/st06_ca/cousub/cs0608591602_lexington_hills/DC10BLK_CS0608591602_000.pdf US Census 2010 map for Lexington Hills CCD 93175] The area covers approximately 54 sqmi , much of it open space, Open Space Authority of Santa Clara County and contains Lake Elsman, Lexington, and Williams reservoirs, as well as the Lexington Reservoir County Park Santa Clara County Parks: Lexington Reservoir and Bear Creek Redwoods Bear Creek Redwoods Open Space Preserve and Sierra Azul Sierra Azul Open Space Preserve open space preserves.