Wetlands (USFWS) (Regulatory and Environmental) The U.S. Fish and Wildlife Service (USFWS) has defined wetlands as follows: Wetlands are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface, or the land is covered by shallow water. For purposes of this classification, wetlands must have one or more of the following three attributes: 1 at least periodically, the land supports predominantly Hydrophytes (Hydrophytic Vegetation), 2 the substrate is predominantly undrained Hydric Soils, and 3 the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season of each year (Wetland Hydrology). The term wetland includes a variety of areas that fall into one of five categories: 1 areas with hydrophytes and hydric soils, such as those commonly known as marshes, swamps, and bogs, 2 areas without hydrophytes but with hydric soils for example, flats where drastic fluctuation in water level, wave action, turbidity, or high concentration of salts may prevent the growth of hydrophytes, 3 areas with hydrophytes but nonhydric soils, such as margins of impoundments or excavations where hydrophytes have become established but hydric soils have not yet developed, 4 areas without soils but with hydrophytes such as the seaweed-covered portion of rocky shores, and 5 wetlands without soil and without hydrophytes, such as gravel beaches or rocky shores without vegetation. While Wetlands and Deepwater Habitats are defined separately, the USFWS approach to a definition views these two regimes as a continuum of an ecological classification system, and therefore both must be considered in an ecological approach to classification. The deepwater habitat/wetland classification includes five major systems: 1 Marine 2 Estuarine 3 Riverine 4 Lacustrine 5 Palustrine The first four of these classifications include both wetland and deepwater habitats, but only the Palustrine System see Wetlands, Palustrine includes only wetland habitats. Wetlands have been found to provide many valuable functions to include groundwater recharge and discharge, flood flow alteration, sediment stabilization, sediment and toxicant retention, nutrient removal and/or transformation, diverse wildlife and aquatic habitats, and recreation see Wetlands, Benefits. Also see Deepwater Habitat. See Appendix D–2 for an explanation of the Wetland and Deepwater Habitat Classification System and more detailed information on these systems.