Water resource subbasin
# Water resource subbasin

A water resource subbasin is the fourth-level subdivision of the United States hydrologic unit system. Water resource subbasins were formerly called water resource cataloging units. There are currently 2,200 water resource subbasins in the system. Water resource subbasins are further subdivided into watersheds and subwatersheds. Water resource basins have a 8-digit Hydrologic Unit Code (HUC).

