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.
Each State data download is available as either a compressed file Geodatabase or a Shapefile (PDF). Both files are compressed by using the .zip format and contain the following layers:
- Wetlands polygon data
- Wetlands Project Metadata (includes image dates and project information)
- Wetlands Historic Map Information*
- Riparian polygon data*
- Riparian Project Metadata (includes image dates and project information)*
- Historic Wetlands*
- Historic Wetlands Project Metadata (includes image dates and project information)*
- Watershed Boundary Dataset (WBD) HUC8 modified**
* If available at the requested location.
** Not include in State downloads.
Not all of Alaska has been digitally mapped by the U.S. Fish and Wildlife Service. Please refer to the Wetlands Mapping Status layer in the Wetlands Mapper Legend to view where wetlands have been mapped in Alaska. The state downloads include a Wetlands Project Metadata layer that identifies where and when wetlands were mapped within the state.
Due to the amount of data being downloaded, the resulting time to download each file may take up to 60 minutes or more, and each file can range in sizes from 1MB to approximately 4GB.
NOTE: Due to the variation in use and analysis of this data by the end user, each of states wetlands data extends beyond the state boundary. Each state includes wetlands data that intersect the 1:24,000 quadrangles that contain part of that state (1:2,000,000 source data). This allows the user to clip the data to their specific analysis datasets. Beware that two adjacent states will contain some of the same data along their borders.