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What sources were used to produce the National Hydrography Dataset (NHD)?

The National Hydrography Dataset (NHD) is a combination of USGS hydrologic digital line graph (DLG) files and Environmental Protection Agency (EPA) reach files, version 3.0 (RF3). U.S. Forest Service Cartographic Feature Files (CFF) and USGS Tagged Vector Hydro (TVH) captured from 7.5-minute printed maps were also used.

Some states also contributed their own stream layer data to the compilation of the 1:24,000-scale NHD. The USGS files were used for spatial accuracy and the EPA files were used for attribute information.

Learn more: Hydrography Standards and Specifications