The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the sream segments or reaches that comprise the nation's surface water drainage system. Medium resolution NHD is based on the content of the U.S. Geological Survey 1:100,000-scale Digital Line Graph (DLG) hydrography data, integrated with reach-related information from the U.S. Environmental Protection Agency Reach File Version 3.0 (RF3). More specifically, it contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent water bodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria established by the Federal Geographic Data Committee.

Additional National Hydrography Resources Available:

NHDPlus is a geo-spatial, hydrologic framework dataset developed by EPA Office of Water with assistance from USGS. NHDPlus has been made available by EPA to the wider water resources community and has been used for many diverse applications including enhanced modeling and analytics. NHDPlus is an integrated suite of application-ready GIS data that incorporate features of the NHD, the National Elevation Dataset (NED), and the Watershed Boundary Dataset (WBD). NHDPlus data is available on a regional scale and located online at: http://www.horizon-systems.com/NHDPlus/index.php.

EPA Office of Water offers web services available on the EPA’s Mapping services page. Non-developers can utilize these services using a variety of mapping and GIS applications. Services can be located online at: http://water.epa.gov/scitech/datait/tools/waters/services/mapping_services.cfm.

NHD Tools: Multiple geospatial tools created to assist in the use and editing of National Hydrography data have been created by USGS, and are located online at: http://nhd.usgs.gov/tools.html#network.

USGS National Map: Maintained by USGS, the National Map provides numerous water related geospatial data including regularly updated Hydrographic databases of the US at multiple scales. Data is located online at: http://nationalmap.gov/small_scale/atlasftp.html?openChapters=chpwater%23chpwater%2Cchpwater#chpwater.