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.
The watershed and subwatershed hydrologic unit boundaries provide a uniquely identified and uniform method of subdividing large drainage areas. These smaller sized hydrologic units (up to 250,000 acres) are useful in many programs supported by the NRCS and others.
This is public information and may be interpreted by organizations, agencies, units of government, or others based on needs; however they are responsible for the appropriate application of the data. Federal, state, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions they make. The Natural Resources Conservation Service will not perform any evaluations of these maps or purposes related solely to State or local regulatory programs. Photographic or digital enlargement of these maps to scales greater than that at which they were originally delineated can cause misrepresentation of the data. If enlarged, the maps will not include the fine detail that would be appropriate for mapping at the small scale. Digital data files are periodically updated. Files are dated, and users are responsible for obtaining the latest version of the data.
The PNWHF Partnership initiated a workshop-oriented process whereby agreed-upon hydrologic boundaries were accepted or delineated using 1:24,000 scale Digital Raster Graphics. A number of new Hydrological Unit Boundaries were also delineated using flow lines and basins computed from 10- and 30-meter horizontal resolution Digital Elevation data based on flow derived from the elevation grid to determine potential pour points. This workshop process resulted in a seamless hydrologic boundary dataset for Oregon.
The PNWHF dataset was made available via its website for operational edits. PNWHF Partners downloaded the dataset, edited boundaries and attribution, and submitted the updated dataset back to the PNWHF server.
The dataset was frozen prior to submittal to the review and edit process, the precursor to NRCS certification.
EDIT_TYPE - Type of edits that took place.
NEW_ACRES- Change in acres after edit.
HUC_10_TYPE - Fifth Level Hydrologic Unit Type
HUC_10_MOD - Fifth Level Hydrologic Unit Modifications
HUC_12_TYPE - Sixth Level Hydrologic Unit Type
HUC_12_MOD - Sixth Level Hydrologic Unit Modifications
Dropped the following attribute fields:
The WBD_Oregon coverage contains attributes for polygons and arcs. Hydrologic Unit delineations are closed polygons that encompass all area draining toward the lowest point (called pour point) in the polygon. Because of nominal sizes for the different hydrologic unit level: Watershed (40,000 to 250,000 acres) and Subwatershed (generally 10,000 to 40,000 acres), some polygons do not include all areas up to the drainage divide but all areas to one or more other upstream hydrologic units. A unique hydrologic unit code is used to identify each hydrologic unit. The hydrologic unit codes start with the 8-digit Sub-basin (huc_8) number that contains the Watershed. Likewise the Subwatershed hydrologic unit codes (huc_12) start with the 10-digit Watershed number (huc_10) that contains the Subwatershed. Attributes associated with a hydrologic unit code includes: ACRES, HUC_10_TYPE, HUC_12_TYPE, HUC_10_MOD, HUC_12_MOD, , HU_8_NAME, HU_10_NAME, HU_12_NAME, STATES, NCONTRB_A, HU_10_DS, HU_12_DS, HUC_MOD, COMMENT, HUC_8, HUC_10, HUC_12, HU_10_GNIS_NUM, HU_12_GNIS_NUM, HUC_LEVEL, LINESOURCE, LINEVER, LINEDATE, LINEORG, META_ID, COMMENT.