I1: Oral Presentation C Thursday, 1:30 � 2:00 pm C Lake Superior Ballroom MN

National Hydrography Dataset

Ron Wencl
U.S. Geological Survey
National Mapping Program
2280 Woodale Drive
Mounds View, MN  55112

The National Hydrography Dataset (NHD) is a digital spatial dataset that provides hydrographic data and information about surface water features for the United States. The NHD is the culmination of cooperative efforts of the U.S. Environmental Protection Agency (EPA) and the U.S. Geological Survey (USGS). It combines elements of USGS Digital Line Graph (DLG) hydrography files and the EPA Reach File Version 3 (RF3). The DLG files contribute a national coverage of features, including water bodies such as lakes, linear water features such as rivers, and point features such as springs. These files provide standardized feature types, delineation, and spatial accuracy. From RF3, the NHD acquires hydrographic sequencing, upstream and downstream flow direction and reach codes. The feature names are from the Geographic Names Information System (GNIS). 

The NHD provides comprehensive coverage of hydrographic data for the United States. Some of the applications of the NHD are multiuse hydrographic modeling and water-quality studies. While initially based on 1:100,000-scale data, the NHD is planned so that it can incorporate the development of the higher resolution data that many users require. The higher resolution data will be incorporated into the NHD through the participation of users at the national, State, and local levels. The common identifiers for the features are the basis for tracking and sharing modifications of features during data maintenance. The NHD will improve the integration of hydrographically related data in support of the varied applications and will also enable shared maintenance and enhancement.