The following definition of wetland is the regulatory definition used by the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (Corps.)
"Those areas that are inundated or saturated by surface or ground water (hydrology) at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation (hydrophytes) typically adapted for life in saturated soil conditions (hydric soils). Wetlands generally include swamps, marshes, bogs, and similar areas" (40 CFR 232.2(r))
The U.S. Army Corps of Engineers regulates wetland uses under authority of the Rivers and Harbors Act and the Clean Water Act. The Corps requires use of the 1987 Corps of Engineers Wetlands Delineation Manual for jurisdictional purposes. The Corps manual utilizes a three-parameter method for identifying wetlands requiring positive indicators of hydrophytic vegetation, hydric soils, and wetland hydrology.