Watershed Boundary Dataset, Hydrologic Unit Code 8 for the Northeast

This data set is a complete digital hydrologic unit boundary layer of the Subbasin (8-digit) 4th level for the entire United States, clipped to the Northeast. A hydrologic unit (HU) is a drainage area delineated to nest a multi-level, hierarchical drainage system. Its boundaries are defined by a hydrographic and topographic criteria that delineate an area of land upstream from a specific point on a river, stream, or similar surfaces waters. An HU can accept surface water directly from upstream drainage areas, and indirectly from associated surface areas such as remnant, non-contributing, and diversions to form a drainage area with single or multiple outlet points. HUs are only synonymous with classic watersheds when their boundaries [...]