United StatM
               Environmental Protection
Offica of Water (WH-556F).
Office of Wattands, Ocaana,
and Watersheds (A-104 F)
EPA843-F-93-001 j
March 1993
               WETLANDS FACT SHEET*   9
               Definition and  Delineation

      Since the 1970's, the U.S. Army Corps of
Engineers (Corps) and the US. Environmental
Protection Agency (EPA) have used the same
definition of wetlands for regulatory purposes:
 Wetlands an anas that an inundated or satu-
 rated 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 anas.

      Basically, wetlands are areas where the
frequent and prolonged presence of water at or
near the soil surface drives the natural system -
the kind of soils that form and the plants that
grow, and the fish and/or wildlife communities
that use the habitat Swamps, marshes and bogs
are well-recognized types of wetlands, but there
aremanyimportantspecific wetland types, such
as vernal pools, playas and prairie potholes, that
have drier or more variable water regimes than
those well-recognized by the general public.

        Field Indicators

      When the upper part of the soil is satu-
rated with water at growing season tempera-
tures, soil organisms consume the oxygen in the
soil, and conditions unsuitable for most plants
quickly develop. Such conditions also cause the
development of soil characteristics (e.g., color
and texture) that are diagnostic of so called
"hydric soils". The plants that can grow in such
conditions are called "hydrophytes" (e.g., marsh
grasses). Together, hydric soilsand hydrophytes
 Wetlands Hotime» at 1-800-832-7828
   are useful field indicators of the presence of
   wetlands and are essential for field identifica-
   tion of wetlands.

         The actual presence or absence of water
   itself (Le., by ponding, flooding, or soil satura-
   tion), however, is a less reliable indicator of the
   presence of wetlands.  Except for wetlands
   flooded by ocean tides, the hydrology of wet-
   lands fluctuates as a result of rainfall patterns,
   snowmelt, dry seasons and droughts. Some of
   the most well-known wetlands, such as the Ev-
   erglades and Mississippi bottomland hardwood
   swamps, are often dry. Conversely, many up-
   land areas are very wet during and shortly after
   wet weather. Such natural fluctuations must be
   taken into account when identifying areas sub-
   ject to federal wetlands jurisdiction.  Similarly,
   the effects of upstream dams, drainage ditches,
   dikes, irrigation and other modifications must
   also be considered.

        Delineation Manual

         EPA and the Corps are currently using
   the 1987 Corps of Engineers Wetlands Delinea-
   tion Manual to delineate wetlands for the Clean
   Water Act Section 404 permit program. Section
   404 requires a pernit from the Corps or autho-
   rized State for the discharge of dredged or fill
   material into the waters of the United States,
   including wetlands. The 1987 Manual will re-
   main in use pending review of public omments
   on the 1991 proposed Manual and the ongoing
   National Academy of Sciences study of  wet-
   lands delineation.
         The 1987 manual organizes field indica-
   tors into three categories- soils, vegetation, and
   hydrology- and has evidence thresholds, or cri-
   teria, for each category. With this approach, an
   area that meets all three criteria is considered a
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