This data set consists of geo-referenced digital map data and associated attributes. The hydrologic unit code attached to each delineated polygon is linked to the attribute data, which can contain information on area in acres, non-contributing area, state(s) the HU falls within, name for 7th and 8th level HU, 5th and 6th level code for downstream hydrologic unit, and hydrologic unit modifications. Each line has attributes that describe the HU level (1-8), originating source for that line and a metadata ID number that links the line to its associated metadata file.
This data set is intended as a tool for water-resource management and planning activities, particularly for site-specific and localized studies, which require the amount of detail provided by a large-scale map.
This is public information and may be interpreted by organizations, agencies, units of government, or others based on needs; however they are responsible for the appropriate application of the data. Federal, state, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions they make. The Natural Resources Conservation Service will not perform any evaluations of these maps or purposes related solely to State or local regulatory programs. Photographic or digital enlargement of these maps to scales greater than that at which they were originally delineated can cause misrepresentation of the data. If enlarged, the maps will not include the fine detail that would be appropriate for mapping at the small scale. Digital data files are periodically updated. Files are dated, and users are responsible for obtaining the latest version of the data.
Hydrologic unit boundaries generally were digitized within 0.01 inches of their locations on the digitizing source. The digital map elements are edge matched against the data for the adjacent Quadrangle. Edge match locations generally do not deviate from centerline to centerline by more than 0.01 inches.