The polygon shapefile identifies parcels within the nine county San Francisco Bay Area Region, California which are accurate identifications of Williamson Act contracted land for the California Open Space Subvention Act Program in Fiscal Year 2006-2007. Refer to Resource Quality entries for attribute table field definitions. The Williamson Act dataset represents parcels within a county with a Type I (a.k.a. "Prime"), Type II (a.k.a. "Sub-Prime") or Open Space Type II Williamson Act (WA). This dataset was developed/compiled for use in the San Francisco Bay Area Upland Habitat Goals Project, a Project used to identify a Conservation Lands Network (CLN) for biodiversity preservation to inform conservation investments and lasting cooperative conservation partnerships. The Conservation Lands Network GIS Database is the primary output of the Project. The data depicts the spatially explicit CLN that is recommended for the nine county San Francisco Bay Area Region, California. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.