Abstract

The Watershed Boundary Dataset (WBD) is a comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. This document establishes interagency guidelines for creating the WBD as seamless and hierarchical hydrologic unit data, based on topographic and hydrologic features across the United States. This document provides guidelines, requirements, and procedures for expanding and revising the previous U.S. Geological Survey (USGS)-Natural Resources Conservation Service (NRCS) national data published in 1994. Expansion is accomplished by creating two additional levels of detailed hydrologic unit boundaries nested within the 1:250,000-scale hydrologic units, and revision occurs through increasing the data resolution to 1:24,000-scale in the conterminous United States, 1:25,000 scale in the Caribbean, and 1:63,360 scale in Alaska. The guideline contains details for compiling the two additional levels, Watersheds (5th-level, 10-digit hydrologic units) and Subwatersheds (6th-level, 12-digit hydrologic units), to be incorporated into the WBD. The guidelines are designed to enable local, regional, and national partners to consistently and accurately delineate watersheds. Such consistency improves watershed management through efficient sharing of information and resources and by ensuring that digital geographic data are usable with other related Geographic Information System (GIS) data.

Terminology, definitions, and procedural information are provided to ensure uniformity in hydrologic unit boundaries, names, and numeric codes. Detailed requirements and specifications for data are included. The document also includes discussion of objectives, communications required to revise the 1:250,000-scale source data, as well as final review and data-quality criteria. Instances of unusual landforms or artificial features that affect the hydrologic units are described with metadata requirements. Up-to-date availability of Watersheds (5th-level hydrologic units) and Subwatersheds (6th-level hydrologic units) is listed at http://www.ncgc.nrcs.usda.gov/products/datasets/watershed/

This publication has been updated and clarified from the previous NRCS guidance document “Federal Standard for Delineation of Hydrologic Unit Boundaries, Version 2.0, October 1, 2004,” through contributions of the WBD Technical Support Team, as requested by the Subcommittee on Spatial Water Data. The USGS online publication is available on the Web at http://pubs.usgs.gov/tm/tm11a3/

Posted March 11, 2009