National Watershed Boundary

This U.S. Geological Survey (USGS) map layer displays the National Watershed Boundary Dataset (WBD). The WBD defines the perimeter of drainage areas formed by the terrain and other landscape characteristics. The drainage areas are nested within each other so that a large drainage area (Upper Mississippi River), will be composed of multiple smaller drainage areas like the Wisconsin River. Each of these smaller areas can be further subdivided into subsequently smaller drainage areas. The intent of defining hydrologic units (HU) for the WBD is to establish a base-line drainage boundary framework, accounting for all land and surface areas. The WBD is a comprehensive aggregated collection of HU data consistent with the national criteria for delineation and resolution. Each HU is identified by a unique hydrologic unit code (HUC). This service includes HU boundaries for HUC2 (Regions), HUC4 (Subregions), HUC6 (Basin), HUC8 (Subbasins), HUC10 (Watersheds), HUC12 (Subwatersheds), and HUC14.