Canada Geese enjoying a wetland. Photo: © William H. Mullins 2004

Defining Wetlands

You'd think the answer to "What is a wetland?" would be easy. No such luck. Scientists, politicians, environmentalists, ranchers, farmers and developers have all been debating the definition of a wetland for over fifty years. Although many definitions of wetlands exist, the two definitions used by the U.S. Government agree that a wetland contains specific:

• Hydrology (amount and period of time that water is present)
• Hydrophytic vegetation (wetland plants adapted to wet soils)
• Hydric soils (soils low or absent in oxygen due to their saturation in water).

The U.S. Fish and Wildlife Service (FWS) says an area need have only one of these conditions to be considered a wetland. The U.S. Army Corps of Engineers (Corps) says an area must have all three conditions before it is considered a wetland. The Corps administers the wetlands provisions of the federal Clean Water Act, so its definition is the one most used by the federal, state, and local governments. The definition, as published in the 1987 Corps of Engineers Wetlands Delineation Manual, says:

"Wetlands are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions."

Within this definition there are many different types of wetlands, and many common names to describe these different wetlands.

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