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General Listing
Title of Listing:
National Wetlands Inventory (NWI) Products
Maps/Geographic Data
US Geological Survey-USGS, All Listings
Document #:
Web Site:

The National Wetlands Inventory (NWI) provides wetlands data. These data provide consultants, planners and resource managers with information on wetland location and type. The standard NWI map product is a 1:24,000-scale map of wetland point, line, and area features overlaid on a United States Geological Survey (USGS) 7.5-minute topographic map. Maps are compiled from National Aerial Photography Program (NAPP) 1:40,000-scale and National High Altitude Photography program (NHAP) 1:58,000- or 1:80,000-scale aerial photography with source dates ranging from the 1980s to the present.

          All photo-interpretable wetlands are mapped. In the treeless prairies, 1_4-acre wetlands are mapped. In forested areas, small open water and emergent wetlands are mapped. In general, the minimum mapping unit is from 1 to 3 acres depending on the wetland type and the scale and emulsion of the aerial photography. In regions of the country where evergreen forested wetlands predominate, wetlands smaller than 3 acres may not be mapped. Thus, a detailed on-the-ground analysis of a single site may result in a revision of the wetland boundaries established through photographic interpretation. In addition, some small wetlands and those obscured by dense forest cover may not be included on the maps.

          The wetlands are classified in accordance with the "Classification of Wetlands and Deepwater Habitats of the United States" by Cowardin et. al., published by the United States Fish and Wildlife Service in 1979 (FWS/OBS - 79/31).

          The 1:3,168,000-scale national map should be used only as a graphic to approximate relative distribution and location of wetlands.

          Digital wetland data are digitized from the 1:24,000-scale wetlands maps into topologically correct data files containing ground planimetric coordinates and wetland attributes.

          USGS Information Services accepts fax and mail orders only.

          Visit the USGS at or
Mapping/GIS, Remote Sensing, Wetlands

Additional Topics/Tags/Keywords
Maps, Aerial Photography, Hydrology, Land, Cover, Surface, Wetlands

US Department of the Interior (DOI), US Geological Survey (USGS)
Information Services
Box 25286
Information Services (800) 435-7627
Earth Science Information Center(800) 872-6277
Zip/Postal Code:
EROS Data Center(605) 594-6151
United States
Fax: Information Services (303) 202-4693
Branch Locations: