National Wetlands Inventory Line Data

The National Wetlands Inventory (NWI) requires that linear features mapped beyond the Federal Geographic Data Committee (FGDC) Wetland Mapping Standard be submitted as lines for all contracts signed after September 30, 2022. These features, also known as narrow linear habitats (NLH), are non-vegetated Cowardin-defined features (Federal Geographic Data Committee, 2013) that are less than 15 feet wide in the United States, as well as U.S. territories. If project goals require the inclusion of NLH features beyond the Wetland Mapping Standard, these features must be submitted to the NWI in a separate linear data layer that is provided within the national dataset schema.  

The submission of a linear data layer is NOT required by NWI to meet the Wetland Mapping Standard. To ensure data quality for those seeking to produce these data, the NWI has provided guidance and requirement documentation, as well as a set of data verification tools to assist data producers.  

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NWI Line Data 

Digital line data are available for download for the U.S. in Geodatabase or Shapefile format in areas where it has been produced. Though linear digital map data can stand alone, it is recommended that this data be used in conjunction with the associated polygonal wetlands and/or riparian riparian
Definition of riparian habitat or riparian areas.

Learn more about riparian
data. This will provide a “complete picture” of the ecological systems that have been mapped.