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Federal
EnviroAtlas - HU12_polygon
U.S. Environmental Protection Agency —
This data set is a complete digital hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for the entire United States. This data set consists of... -
Federal
National Hydrography Dataset Plus - NHDPlus
U.S. Environmental Protection Agency —
This high-level metadata data document will be supplemented with detailed regional metadata at a later date. The NHDPlusV2 is an integrated suite of application-ready...