Classification of Wetlands and Deepwater 

 Habitats of the United States 



by 

 Lewis M. Cowardin 



U.S. Fish and Wildlife Service 



Northern Prairie Wildlife Research Center 



Jamestown, North Dakota 58401 



Virginia Carter 

 U.S. Geological Survey, Reston, Virginia 22092 



Francis C. Golet 



Department of Natural Resources Science 

 University of Rhode Island, Kingston, Rhode Island 02881 



and 



Edward T. LaRoe 



U.S. National Oceanographic and Atmospheric Administration 



Office of Coastal Zone Management 



Washington, D.C. 20235 



Abstract 



This classification, to be used in a new inventory of wetlands and deepwater habitats of the United 

 States, is intended to describe ecological taxa, arrange them in a system useful to resource managers, 

 furnish units for mapping, and provide uniformity of concepts and terms. Wetlands are defined by 

 plants (hydrophytes), soils (hydric soils), and frequency of flooding. Ecologically related areas of deep 

 water, traditionally not considered wetlands, are included in the classification as deepwater habitats. 



Systems form the highest level of the classification hierarchy; five are defined— Marine, Estuarine, 

 Riverine, Lacustrine, and Palustrine. Marine and Estuarine Systems each have two Subsystems, Sub- 

 tidal and Intertidal; the Riverine System has four Subsystems, Tidal, Lower Perennial, Upper Peren- 

 nial, and Intermittent; the Lacustrine has two, Littoral and Limnetic; and the Palustrine has no 

 Subsystems. 



Within the Subsystems, Classes are based on substrate material and flooding regime, or on vegetative 

 life form. The same Classes may appear under one or more of the Systems or Subsystems. Six Classes 

 are based on substrate and flooding regime: (1) Rock Bottom with a substrate of bedrock, boulders, 

 or stones; (2) Unconsolidated Bottom with a substrate of cobbles, gravel, sand, mud, or organic material; 

 (3) Rocky Shore with the same substrates as Rock Bottom; (4) Unconsolidated Shore with the same 

 substrates as Unconsolidated Bottom; (5) Streambed with any of the substrates; and (6) Reef with 

 a substrate composed of the living and dead remains of invertebrates (corals, mollusks, or worms). 

 The bottom Classes, (1) and (2) above, are flooded all or most of the time and the shore Classes, (3) 

 and (4), are exposed most of the time. The Class Streambed is restricted to channels of intermittent 

 streams and tidal channels that are dewatered at low tide. The life form of the dominant vegetation 

 defines the five Classes based on vegetative form: (1) Aquatic Bed, dominated by plants that grow 

 principally on or below the surface of the water; (2) Moss-Lichen Wetland, dominated by mosses or 

 lichens; (3) Emergent Wetland, dominated by emergent herbaceous angiosperms; (4) Scrub-Shrub 

 Wetland, dominated by shrubs or small trees; and (5) Forested Wetland, dominated by large trees. 



The Dominance Type, which is named for the dominant plant or animal forms, is the lowest level 

 of the classification hierarchy. Only examples are provided for this level; Dominance Types must be 

 developed by individual users of the classification. 



Modifying terms applied to the Classes or Subclasses are essential for use of the system. In tidal 

 areas, the type and duration of flooding are described by four Water Regime Modifiers: subtidal, 

 irregularly exposed, regularly flooded, and irregularly flooded. In nontidal areas, eight Regimes are 

 used: permanently flooded, intermittently exposed, semipermanently flooded, seasonally flooded, 

 saturated, temporarily flooded, intermittently flooded, and artificially flooded. A hierarchical system 



