Using ArcGIS to Determine the Long-Term Impacts of Anthropogenic Freshwater Runoff on Los Peñasquitos Lagoon in San Diego, CA

Many areas of northern San Diego County experienced a population boom in the 1980’s. This increase in population resulted in the urbanization of watersheds. As the landscape of these watersheds changed, so too did the coastal ecosystems they fed into. This project used GIS to analyze the impact of increased freshwater input (using urbanization as a proxy) on a northern San Diego County estuary, Los Peñasquitos Lagoon. This research extends earlier work titled, Vegetation Type Conversion in Los Peñasquitos Lagoon, California: An Examination of the Role of Watershed Urbanization, (Greer & Stow 2003). The vegetation within the lagoon was mapped from 1929-2018 using aerial images and historical data and analyzed for change in relation to urbanization. A shift from saltwater-associated vegetation to freshwater-associated vegetation suggests decreasing salinity in the lagoon. This increased freshwater correlates with increasing urbanization in land use within the watersheds. The change in this vegetation has the potential to impact the fauna within the lagoon and change how the ecosystem, as a whole, functions.