National Wetlands Inventory

The National Wetlands Inventory (NWI) is the U.S. Fish and Wildlife Service's national repository for digital wetlands map data.

The Yellowstone River Conservation Districts Council obtained a grant from the Montana Land Information Advisory Council in 2009 to fund the Montana Natural Heritage Program to map wetlands and riparian areas in 54 7.5-minute quadrangles along the lower Yellowstone River and add them to the NWI and the Montana Wetlands and Riparian Framework.

The completed mapping includes wetland polygons that have been classified using the Classification of Wetlands and Deepwater Habitats of the United States (Cowardin et al. 1979).  Wetland polygons were also attributed with hydrogeomorphic modifiers that link polygon types to wetland functions.  Riparian polygons were mapped and classified according to A System for Mapping Riparian Areas in the Western United States (USFWS 1997).  Field reconnaissance trips were conducted as necessary to determine whether polygons were correctly classified, and to review any questionable types, and to gather data on wetlands of particular ecological significance, which will be documented in the MTNHP site database. Quality assurance/ Quality control followed National Standards and Quality Components (USFWS 2004).

These data and wetlands data for the entire river corridor in Montana are available in the Montana Wetland and Riparian Framework (MWRF):