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Federal
National Hydrography Dataset (NHD) - USGS National Map Downloadable Data Collection NGDA
Department of the Interior —
The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's... -
Federal
USGS Surface-Water Data for the Nation - National Water Information System (NWIS)
Department of the Interior —
The USGS compiles online access to water-resources data collected at approximately 1.5 million sites in all 50 States, the District of Columbia, Puerto Rico, the... -
Federal
Base-flow index grid for the conterminous United States
Department of the Interior —
This 1-kilometer raster (grid) dataset for the conterminous United States was created by i nterpolating base-flow index (BFI) values estimated at U.S. Geological... -
Federal
Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Level 3 Ecoregions
Department of the Interior —
This data set represents the estimated area of level 3 ecological landscape regions (ecoregions), as defined by Omernik (1987), compiled for every catchment of... -
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...