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Watershed Boundary Dataset (WBD) Facts

History

• 1974 - USGS / Water Resources Council mapped and published the 2-, 4-, 6-, and 8-digit drainages.
• 1970’s-80’s - SCS (now the NRCS) mapped Watersheds and Subwatersheds. (Standards were few and dependent on local use or sponsor needs.)
• 1992 - SCS National Instruction (NI 170-304) released for Hydrologic Unit mapping and digitizing. Provided a comprehensive set of instructions on delineating boundaries and digitizing.
• 1996 - Comments received from USGS, FS and BLM on working draft. Many comments incorporated into standard, two delineation criteria differences exist.
• 2000 - Federal Standards for Delineation of Hydrologic Unit Boundaries out for FGDC-Spatial Water Data Subcommittee member review and comment. Even though it is in draft format, states should be using it as the official guideline in 10 and 12-digit hydrologic unit delineation.
• 2001 - December 6; The Spatial Water Data Subcommittee approved Version 1.0 of the Federal Standards for Delineation of Hydrologic Unit Boundaries.
• 2004 - October 1; The Spatial Water Data Subcommittee approved Version 2.0 of the Federal Standards for Delineation of Hydrologic Unit Boundaries.

Criteria

• Scale at 1:24,000 and the base data meets or exceeds the USGS 7.5 Quad Sheets.
• Delineation Basis
• Hydrologically based
• Crosses stream at confluence
• May cross at other points if other HUs at same level are upstream
• No delineations running down stream centerline

Interagency Standard

• Interagency Standard for Delineation of Hydrologic Unit Boundaries
• Sponsored by the Federal Geographic Data Committee (FGDC)
• Subcommittee on Spatial Water Data with members from the:
• Natural Resources Conservation Service
• USGS
• Forest Service
• Bureau of Land Management
• Corp of Engineers
• Environmental Protection Agency
• Federal Emergency Management Agency
• National Oceanic and Atmospheric Administration
• National Weather Service