Description: Summary
The Watershed and Subwatershed hydrologic unit boundaries provide a uniquely identified and uniform method of subdividing large drainage areas. The smaller sized 6th level sub-watersheds (up to 250,000 acres) are useful for numerous application programs supported by a variety of local, State, and Federal Agencies. This data set is intended to be used as a tool for water-resource management and planning activities, particularly for site-specific and localized studies requiring a level of detail provided by large-scale map information. The dataset is seamless and, for the most part, a nationally consistant geospatial database. Description
This data set is a complete digital hydrologic unit boundary layer of the Subbasin (8-digit) 4th level for the entire United States. This data set consists of geo-referenced digital data and associated attributes created in accordance with the "Federal Guidelines, Requirements, and Procedures for the National Watershed Boundary Dataset; Chapter 3 of Section A, Federal Standards, Book 11, Collection and Delineation of Spatial Data; Techniques and Methods 11-A3" (04/01/2009). http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/water/watersheds/?cid=nrcs143_021630 . Polygons are attributed with hydrologic unit codes, name, and size. The data is currently updated through the USGS National Hydrography Dataset (NHD) Program and replicated to NRCS twice per year.
Copyright Text: Funding and support for the Watershed Boundary Dataset (WBD) were provided by the Natural Resources Conservation Service, the Environmental Protection Agency, and the United States Geological Survey. Representatives from the U.S. Geological Survey and Environmental Protection Agency contributed a substantial amount of time and salary towards quality review and updating of the dataset in order to meet the Federal Standards for Delineation of Hydrologic Unit Boundaries.