NWI data can be accessed in several ways depending on your needs. To display and query wetlands data in your software application please use our Web Map Services. This will ensure you have the latest data and reduce data management overhead. If you need to conduct GIS analysis please reference the information below to download the data by watershed or by state. For downloads larger than a state, please contact the Wetlands Team to request a custom download.
Please note that NWI data is continuously being improved and new data is added on a biannual basis. Those updates are reflected on the Wetlands Mapper and in the data downloads in October and May of each year. To ensure that you have the most up to date information, please refer to the published date in the metadata, the location of new data on the Projects Mapper and download new data regularly.
Data can be downloaded by HUC 8 Watershed Boundary or by State. The data is downloaded as a .zip file that contains the following layers:
Information about each of these layers can be found on our Metadata page.
Detailed documentation of the Cowardin Classification system can be found on our Wetland Code page. Here you can also download the NWI Code Definitions Table that provides users with the full wetland or deepwater habitat description within their own mapping application.
Wetlands data viewed on the Wetlands Mapper can be downloaded by HUC8 watershed or by State or U.S. Territory in either file Geodatabase or Shapefile (PDF) format. The Wetlands Mapper 'Get Data' button allows data to be downloaded by HUC8 watershed or by State. The State Downloads page allows data to be downloaded by state.
You can view the Geodatabase and Shapefiles by using ESRI's ArcGIS Explorer free software, among others. Please note that ArcGIS version 10.* is required for Geodatabase downloads.
State and watershed data downloaded will be in an equal area Albers projection with a North American Datum (NAD) of 1983.
*AutoCAD* users: In order to view NWI data you must first add the Albers projection information into your AutoCAD library. Do this by using the MAPSCSCREATE command and click ‘c’ for coordinate system. Then input the Albers specific projection information.