The National Land Cover Database 2001 (NLCD) for mapping zone 03 was produced through a cooperative project conducted by the Multi-Resolution Land Characteristics (MRLC) Consortium. The MRLC Consortium is a partnership of federal agencies (www.mrlc.gov), consisting of the United States. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the United States Environmental Protection Agency (EPA), the United States Department of Agriculture (USDA), the United States Forest Service (USFS), the National Park Service (NPS), the United States Fish and Wildlife Service (FWS), the Bureau of Land Management (BLM) and the United States Department of Agriculture Natural Resources Conservation Service (USDA NRCS). One of the primary goals of the project is to generate a current, consistent, seamless and accurate National Land Cover Database (NLCD) circa 2001 for the United States at medium spatial resolution. For a detailed definition and discussion on MRLC and the NLCD 2001 products, refer to Homer et al. (2003) and http://www.mrlc.gov/mrlc2k.asp. The NLCD 2001 was created by partitioning the United States into mapping zones. A total of 66 mapping zones were delineated within the conterminous United States based on ecoregion and geographical characteristics, edge matching features and the size requirement of Landsat mosaics. This raster dataset depicts the mapping zone 03 for impervious surfaces and encompasses the nine county San Francisco Bay Area Region of California. Impervious surfaces include mainly artificial structures, such as pavements (roads, sidewalks, driveways and parking lots) and rooftops that are covered by impenetrable materials such as asphalt, concrete, brick and stone. Soils compacted by urban development are also highly impervious. 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.