What is the National Hydrography Dataset?
The National Hydrography Dataset is the culmination of recent cooperative efforts of the U.S. Environmental Protection Agency (EPA) and U.S. Geological Survey (USGS). It combines the best of the EPA Reach File Version 3.0 (RF3) and USGS Digital Line Graph (DLG) hydrography files: hydrologic ordering, hydrologic navigation for modeling applications, and a unique identifier (reach code) for surface water features from RF3; and the spatial accuracy and comprehensiveness of DLG hydrography. What are the advantages of the NHD? The National Hydrography Dataset is designed to provide comprehensive coverage of hydrologic data for the US. While based on 1:100,000-scale data, the National Hydrography Dataset is designed to incorporate–and encourage the development of–higher-resolution data required by many users. It will also facilitate the improved integration of hydrologically-related data in support of the application requirements of a growing national user community and will enable shared
