Wetland Types

Wetlands can be classified and assessed in many ways. Delineating and classifying wetlands is complex and must be conducted by wetland experts. In Minnesota the Wetland Conservation Act (WCA) prescribes the methods used for delineating wetland boundaries, determining wetland types and assessing wetland functions.

Wetland Classifications and Types

The Minnesota Wetland Conservation Act requires wetland types be determined according to Wetlands of the United States, (1971 edition) and the Minnesota Wetland Conservation Act also adopts by reference the Classification of Wetlands and Deepwater Habitats of the United States.

Classification of Wetlands and Deepwater Habitats of the United States - National Wetlands Inventory
The most widely used formal wetland classification system in the United States is the U.S. Fish and Wildlife Service classification system developed by Cowardin et al. (1979). This system is the basis for the National Wetlands Inventory maps.

Deepwater Habitats of the United States - Circular 39
An older system described in Circular 39 of the U.S. Fish and Wildlife Service (Shaw and Fredine 1956) is simpler and still used in some areas. The Cowardin system superseded Circular 39 in 1979.

The U.S. Army Corps of Engineers also recognizes the hydrogeomorphic classification.

Hydrogeomorphic Classification
In 1993 the Corps published a report titled “A hydrogeomorphic classification for wetlands”, whose purpose is to facilitate the development of improved models for evaluation of wetland functions by grouping functionally similar wetland types. The hydrogeomorphic (HGM) classification is not meant to replace other wetland classification systems.

Source: Wetlands Management Handbook, U.S. Army Engineer Research and Development Center