Polygon feature class representing major watersheds in Philadelphia. Data was developed originally from either USGS and the 2004 Sanborn DEM (digital elevation model) using ArcHydro watershed extraction tools. Major Watersheds are dissolved from subshed boundaries which reflect surface flow in relationship to stormwater inlets and outfalls. Trouble downloading or have questions about this City dataset? Visit the [OpenDataPhilly Discussion Group](http://www.phila.gov/data/discuss/)