USEPA defines wetlands as areas that are inundated or saturated by surface or ground water 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. Wetlands generally include swamps, marshes, bogs, and similar areas.

Wetland systems can be identified through the presence of hydrophytic vegetation, hydric soils, and wetland hydrology.

Hydrophytic vegetation are plants which must be in water, either completely or partially submerged, for part of their life cycle.

Wetland hydrology describes the events that contribute to anaerobic conditions which can include overbank flooding, upwelling of groundwater, or surface runoff.