This polygon shapefile depicts land areas within the County of San Mateo, California that receive tax breaks under the Williamson Act. The California Land Conservation Act, better known as the Williamson Act, has been the California’s agricultural land protection program since its enactmentin1965. The Williamson Act preserves agricultural and open space lands through property tax incentives and voluntary restrictive use contracts. Private landowners voluntarily restrict their land to agricultural and compatible open space uses under minimum ten year rolling term contracts with local governments. In return, restricted parcels are assessed for property tax purposes at a rate consistent with their actual use, rather than potential market value. This layer is part of a collection of GIS data for San Mateo County, California.This coverage can be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analyses of geospatial data.