In 2016, Debbie Waldecker from California State Parks (CSP) led a team in a strongly field-based update of the Western San Diego County Vegetation dataset for Border Field State Park, located in the southern portion of the mapping area. This mapping effort was conducted to support decisions regarding a road renovation project within the state park. The MMU was 0.4 ha for the majority of the park, with smaller polygons present in the area along the road. Dr. Kellie Uyeda of the Tijuana River National Estuarine Research Reserve and Dr. John Boland of Boland Ecological Services combined the maps produced by SFEI and CSP and assessed each polygon individually to ensure that a MMU of 0.1 ha was applied consistently across the mapping area. We made exceptions to the MMU for polygons that were part of our original field-based rapid assessment plots. Image interpretation was based on a combination of sources, including four-band (red, green, blue, NIR) orthoimagery collected in 2016 by Near Earth Observation Systems, LTD (15 cm spatial resolution), 2016 National Aerial Imagery Program four-band orthoimagery (60 cm spatial resolution), 2014 U.S. Geological Survey (USGS) four-band orthoimagery (10 cm spatial resolution), and 2014 USGS lidar point clouds (11 pts/m2). The lidar point clouds were processed to produce a digital elevation model and a canopy height layer. In addition, we conducted extensive ground reference surveys from 2016 - 2018, collecting over 3,700 geotagged photos across the mapping area. We mostly mapped to the association level, although in some highly disturbed sites where the exact species composition could not be clearly determined, we mapped only to the group level (Mediterranean California Naturalized Annual and Perennial Grassland Semi-Natural Stands and Naturalized Warm-Temperate Riparian and Wetland Semi-Natural Stands). Group and alliance level classes are noted in the association field with an asterisk. The vegetated habitats were based on the Western San Diego County Vegetation dataset, produced in 2012 by San Diego Association of Governments (SANDAG) with a minimum mapping unit (MMU) of 1 hectare (ha) for terrestrial systems and 0.5 ha for wetlands. Developed areas were mapped using the National Land Cover Dataset of 2011 with a MMU of 0.09 ha. Tidal channels and mudflats were based on the Southern California Wetlands Mapping Project from 2005 with a MMU of 0.2 ha. SFEI also conducted supplemental mapping based on aerial imagery from 2008 – 2010 to provide full coverage of the study area.