Description This dataset is a complete digital hydrologic unit boundary layer to the subwatershed (12-digit) 6th level at 1:24,000 scale. It consists of geo-referenced digital data and associated attributes created in accordance with the Federal Standard for Delineation of Hydrologic Unit Boundaries. The hydrologic unit boundaries provide a uniquely identified and uniform method of subdividing large drainage areas, defining the aerial extent of surface water drainage to a point. "Watershed" hydrologic units (HU) are generally subdivided into 5 to 15 units. The average size of an 8-digit sub-basin hydrologic unit is about 450,000 acres. The typical 10-digit watershed size is 40,000 to 250,000 acres, while the typical 12-digit subwatershed is 10,000 to 40,000 acres. 8- and 10-digit watersheds can be derived from 12-digit watershed shapefiles.