Freshwater Wetlands - Hydro-Environmental Analysis: Freshwater Environments - page 515

Forested swamps

Shrub swamps

FIGURE 19.6 Examples of swamps. (From the National Wetlands Research Center.)

frequently called bottomland hardwood swamps. In the Northwest, the dominant trees include wil-
lows ( Salix spp.) and western hemlock ( Tsuga sp.). Brush swamps are commonly dominated by
shrubs, such as the buttonbush or smooth alder and are frequently found near or associated with
forested swamps.

19.3 WETLAND IDENTIFICATION AND CLASSIFICATION
The types of wetlands previously discussed represent a very diverse assemblage of ecological sys-
tems. This diversity makes it dificult to develop a universally accepted deinition of wetlands,
and such a deinition will vary depending on the purpose of that deinition (e.g., scientiic study or
regulatory purpose). Similarly, a wide variety of classiication systems has been developed for vari-
ous purposes, such as the scientiic study of wetlands, to establish trends in wetlands, or to identify
systems as wetlands in order to preserve and protect them (regulatory classiication).
One example of a wetland identiication system is that developed for identifying whether a sys-
tem is subject to protection under Section 404 of the CWA. Under Section 404, discussed in detail
in the following sections as it relates to wetlands, a permit is required from the U.S. Army Corps
of Engineers (the Corps) for the discharge of dredged or ill material into any waters of the United
States, including wetlands. Therefore, the Corps has to have criteria that it can use in this process
to identify if a particular system is a “water of the United States,” and then whether that system is
a wetland (a “jurisdictional” determination). The methods developed to delineate a wetland were
published in the “Corps of Engineers wetland delineation manual” in 1987 (USACE 1987). In that
manual, the Corps speciied the criteria to be used to establish whether or not a system is a wetland,
subject to protection under the CWA. The criteria were based on the presence of three factors:

1. Hydrophytic vegetation

2. Wetland hydrology

3. Hydric soils

The manual also stressed the need for “sound professional judgment, providing latitude to dem-
onstrate whether an area is a wetland or not based on a holistic and careful consideration of evidence