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    Federal
USGS Water-Quality 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
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
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
Attributes for NHDplus Catchments (Version 1.1) for the Conterminous United States: Population Density, 2000
Department of the Interior —
This data set represents the average population density, in number of people per square kilometer multiplied by 10 for the year 2000, compiled for every catchment of... - 
  
    Federal
Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Hydrologic Landscape Regions
Department of the Interior —
This data set represents the area of Hydrologic Landscape Regions (HLR) compiled for every catchment of NHDPlus for the conterminous United States. The source data... - 
  
    Federal
Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Physiographic Provinces
Department of the Interior —
This dataset represents the area of each physiographic province (Fenneman and Johnson, 1946) in square meters, compiled for every catchment of NHDPlus for the... - 
  
    Federal
Attributes for NHDPlus Catchments (Version 1.1) in the Conterminous United States: Bedrock Geology
Department of the Interior —
This data set represents the area of bedrock geology types in square meters compiled for every catchment of NHDPlus for the conterminous United States. The source...