This geospatial dataset represents the 6th level (12-digit) hydrologic unit boundaries from the Watershed Boundary Dataset (WBD) layer for Oregon. Hydrologic units within the WBD_OR_HUC_12 represent drainage areas delineated to the 6th level drainage systems. Their boundaries are defined by hydrographic and topographic criteria that delineate an area of land upstream from a specific point on a river, stream, or similar surface waters. Hydrologic units within the WBD_OR_HUC_12 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. Boundaries within the WBD_OR_HUC_12 were delineated by Pacific Northwest (PNW) Hydrography Framework Partners to meet state requirements and to contribute to the national WBD repository. To meet these goals, the WBD must adhere to the "Federal Standards for Delineation of Hydrologic Unit Boundaries", dated October, 2004. These HUC_12 boundaries were made from the Oregon dataset that has been given national certification by Natural Resources Conservation Service (NRCS) Prior to submission the dataset was subjected to an iterative review and edit process to ensure that the hydrologic boundaries fully satisfy the federal standards. This work was completed under a Memorandum of Understanding between the Pacific Northwest Hydrography Framework Partnership and the US Geological Survey (USGS). The current dataset includes all 6th level boundaries that are in all 4th level (8-digit) subbasins that fall within or intersect the Oregon state boundary.