Estuarine drainage area boundaries for the conterminous United States

To quantify the potential for landward migration at the estuary level, we developed a geospatial dataset for the conterminous United States (CONUS) that identifies the boundaries for estuarine drainage areas. Nine estuarine drainage areas in south Florida were delineated using data developed by the South Florida Water Management District (SFWMD 2018). For the rest of CONUS, we used information contained within the National Fish Habitat Action Plan (NFHAP) - Coastal Spatial Framework (CSF) (National Centers for Coastal Ocean Science 2021). The original NFHAP-CSF data included 612 drainage areas, which were too many for our purposes. Therefore, we merged smaller drainage areas with larger, adjacent drainage areas to reduce the number to 166, which includes 62, 39, and 65 estuarine drainage areas along the Pacific, Gulf of Mexico, and Atlantic coasts, respectively. To ensure that all coastal ecosystems were included, the near-coast estuarine drainage area boundaries were expanded oceanward with a 25-km buffer.