National Hydrography Dataset and Watershed Boundary Dataset
Overview
The National Hydrography Dataset (NHD) is a comprehensive set of digital spatial data that contains information about surface water features such as lakes, ponds, streams, rivers, springs, and wells.
The Watershed Boundary Dataset (WBD) defines the areal extent of surface water drainage to a point, accounting for all land and surface areas.
The NHD is stored in and distributed as a geodatabase. The NHD geodatabase contains two feature datasets: Hydrography and WBD. The Hydrography Feature Dataset contains the classic NHD features and the WBD Feature Dataset includes the WBD Hydrologic Units. Subbasins along the US/Canadian boundary now include NHD and WBD into Canada at the 8-digit level.
NHD/WBD Stewardship
National Stewardship of the NHD & WBD relies heavily on State Stewards. State Stewards are tasked with representing the interests of the state's hydrography user community and providing the USGS with the most widely-accepted representation of surface water in the given state.
The Idaho NHD & WBD are actively updated through this NHD/WBD Stewardship Program. Through MOU and other agreements with the United States Geological Survey (USGS), IDWR was named the Principal Steward for the NHD & WBD in Idaho. IDWR accepts input from other agencies and organizations, considers any changes to the NHD/WBD, and updates the NHD/WBD if appropriate. The Principal Steward adjudicates any decision through the Hydrography Technical Working Group (TWG), if necessary.
The following documents are reference documents used by Idaho Sub-Stewards editing the NHD:
The Idaho Map (TIM)
The Idaho Map (TIM) is a collection of Framework Data Themes as envisioned in the Idaho Spatial Data Infrastructure Strategic Plan. TIM contains 14 Framework layers which encompass the federally-recognized geospatial framework data layers, as outlined by the National Spatial Data Infrastructure (NSDI) Framework and described by the Federal Geographic Data Committee (FGDC), and additional layers defined by the Idaho GIS Community. Datasets are recognized though a process outlined in the Idaho Technology Authority Guideline 350. Hydrography is one of the identified Framework Layers described in TIM and has two recognized Data Elements: Watersheds and Water Features.
- The WBD is recognized by the Idaho Geospatial Council Executive Committee (IGC-EC) as the Framework Dataset of the Watershed Element of the Hydrography Framework Data Theme for Idaho.
- The NHD is recognized by the IGC-EC as the Framework Dataset for the Water Features Element of the Hydrography Framework Data Theme for Idaho.
The framework approach is a collaborative effort to create a widely-available source of basic geographic data. It provides the most common data themes geographic data users need as well as an environment to support the development and use of these data. The framework represents "data you can trust"—the best available data for an area, certified, standardized, and described according to a common standard. It provides a foundation on which organizations can build by adding their own detail and compiling other data sets. (https://www.fgdc.gov/initiatives/framework/index_html/)