1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, and 2011. County of San Mateo Information Services Department. This polygon shapefile depicts land areas within the County of San Mateo, California that receive tax breaks under the Williamson Act. The Californ... County of San Mateo Information Services Department.