Watershed Boundary Dataset
The newly released Natural Resources Conservation Service Hydrologic Unit Code (HUC) 12-digit Watershed Boundary Dataset (WBD) provides one of the fundamental frameworks upon which analysis and reporting of WATERS programs takes place.
The older 8-digit Watershed Boundary Dataset is now referred to as the "legacy" WBD for clarity. To allow for migration activities the legacy WBD is also stored in WATERS.
Many WBD layers are provided as mapping services. See WATERS mapping services for more information.
NRCS Watershed Boundary Datasets:
12-digit subwatershed region polygons as released by Natural Resources Conservation Service.
10-digit watershed subregion polygons aggregated by Hydrologic Unit Code.
8-digit subbasin polygons aggregated by Hydrologic Unit Code.
6-digit basin polygons aggregated by Hydrologic Unit Code.
4-digit subregion polygons aggregated by Hydrologic Unit Code.
2-digit region polygons aggregated by Hydrologic Unit Code.
Legacy Watershed Boundary Datasets:
8-digit legacy subbasin polygons. Generalized layer features point removal to about 75 meters.
6-digit legacy basin polygons. Generalized layer features point removal to about 75 meters.
4-digit legacy subregion polygons. Generalized layer features point removal to about 75 meters.
2-digit legacy region polygons. Generalized layer features point removal to about 75 meters.
Storage Details for WBD Layers
- WBD tables are stored in the waters_wbd schema with all tables publically accessible to internal users at EPA.
- WBD tables are stored in the same coordinate space (NAD83) as RAD and NHD layers.
- WBD tables are registered to ArcSDE allowing use by any internal EPA ESRI client.
- NRCS WBD tables are named indicating the vintage of the data (i.e. WBD20090316_HUC12_OS). To account for future updates to the WBD, each table has a spatial view with no vintage information in the name (i.e. WBD_HUC12_OS). The view should be used when hard-coding tablenames in services and procedures. By using the generic view name, the developer can be assured that they will pull the most recent information available in the WATERS instance. No such naming scheme is required for legacy WBD datasets.
- All views of the WBD layers are ArcSDE registered spatial views.