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Federal
Watershed Boundary Dataset (WBD) - USGS National Map Downloadable Data Collection NGDA
Department of the Interior —
The Watershed Boundary Dataset (WBD) is a comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and... -
Federal
Attributes for NHDPlus Catchments (Version 1.1): Level 3 Nutrient Ecoregions, 2002
Department of the Interior —
This data set represents the area of each level 3 nutrient ecoregion in square meters, compiled for every catchment of NHDPlus for the conterminous United States. The...