Hydrologic unit boundaries define the areal extent of surface water drainage to a point. In the 1970's the USGS developed a hierarchical system for the country. Over the past five years this hierarchical system has been expanded to include more refined boundary subdivisions. These new boundary subdivisions include the 10-digit Hydrologic Units (Watersheds between 40,000 to 250,000 acres) and the 12-digit Hydrologic Units (Sub Watersheds up to 40,000 acres). These resulting boundaries serve as important analysis and reporting units for the PNWHF partners.
The WBD underwent a national certification and improvement exercise in 2006-2008. This activity greatly improved the quality and collective ownership of the dataset. Stewardship of the WBD now ensures continuing improvement and adherance to the agreed-upon set of national standards. More>>
It recognizes ongoing stewardship roles at the national level, and hierarchically, within each state. Communication and collaboration is encouraged. Stewardship recognizes on-the-ground knowledge of the stewards and sub-stewards within each state. It ensures availability of the WBD dataset for maintenance and improvement, analysis, mapping and reporting activities. And lastly, it allows for the effective integration of these activities with similar activities for the NHD.
As with the NHD, the PNWHF Partners are committed to improving the quality of the WBD through time. Each Partner is primarily responsible for data quality for the portion of the WBD on lands under their jurisdiction. Each partner also serves as a conduit for moving proposed updates through the PNWHF stewardship process. Any user of the WBD may submit proposed edits to the stewardship process. The WBD State Stewards for Oregon and Washington have agreed to review and process proposed updated on a bi-annual basis. Proposed updates for each maintenance cycle should be submitted prior to either October 1st or April 1st. Please contact the following individuals if you identify a need for improvement to the dataset.
During the winter of 2013-14, edits were made to the Oregon and Washington portion of the WBD. This included several PNW Hydrography Framework (PNWHF) partner organization edits. The updated WBD is now available from this PNWHF website via the below links.
The WBD 10 and 12 Digit Hydrologic Units (Watersheds and Sub Watersheds) serve as "containers" for a variety of analytical and reporting purposes. PNWHF Partners use these units for many types of "watershed analysis" projects. More>>
To list a few examples, the BLM uses the WBD to support analysis of slope impact with regard to wood debris flow potential, determining rain on snow susceptibility, estimating peak water flow calculations, defining riparian management areas, evaluating and summarizing fish habitat restoration capacity, and determining slope sediment susceptibility. The NRCS in Washington State uses the WBD for River Basin studies, Watershed Protection and Flood Prevention studies, Rapid Watershed Assessments, and several other uses. Karen Hanson at USGS recently developed a WBD poster that lists additional information about the WBD and its uses.
Has your organization used the WBD in innovative ways? Please send brief descriptions of such uses to Jay Stevens (BLM – Gerald_Stevens@blm.gov) or Sheri Schneider (USGS – email@example.com) and they will be shared on this website.