This raster layer is a void-filled digital elevation model (DEM) of North America at 15 arc-seconds resolution. Elevation is expressed in meters and referenced to the WGS84 EGM96 geoid. The primary data s ource of HydroSHEDS is the digital elevation model of the Shuttle Radar Topography Mission. SRTM elevation data were obtained by a specially modified radar system that flew onboard the Space Shuttle Endeavor during an 11-day mission in February of 2000. Regions of no-data (voids), specifically mountainous regions, or those over large water bodies prevented the production of reliable elevation data. The existence of no-data in the DEM causes significant problems for deriving hydrological products, which require continuous flow surfaces. Therefore, a void-filling procedure has been applied to provide a continuous DEM for HydroSHEDS.The goal of developing HydroSHEDS was to generate key data layers to support regional and global watershed analyses, hydrological modeling, and freshwater conservation planning at a quality, resolution and extent that had previously been unachievable.