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Some important definitions to consider...


Wetland Restoration Activities


Wetland mitigation is generally the development of wetland habitat in compensation for destroying or impairing other wetland habitat. For more information on wetland mitigation see the EPA wetland mitigation website.

The EPA defines mitigation

Mitigation, a term that frequently occurs in discussions of restoration, "refers to the restoration, creation, or enhancement of wetlands to compensate for permitted wetland losses" (Lewis, 1989). Under Section 404 of the Clean Water Act, wetlands may legally be destroyed, but their loss must be compensated for by the restoration, creation, or enhancement of other wetlands. In theory, this strategy should result in "no net loss" of wetlands. For a recent analysis of the effectiveness of wetland mitigation, see articles by J. Zedler (1996) and M. S. Race and M. S. Fonseca (1996) in the scientific journal, Ecological Applications.[1]

Mitigation rule

On March 31, 2008, EPA and the U.S. Army Corps of Engineers (the Corps) issued revised regulations governing compensatory mitigation for authorized impacts to wetlands, streams, and other waters of the U.S. under Section 404 of the Clean Water Act. These regulations are designed to improve the effectiveness of compensatory mitigation to replace lost aquatic resource functions and area, expand public participation in compensatory mitigation decision making, and increase the efficiency and predictability of the mitigation project review process. Here is a fact sheet about the rule.

Wetland Construction or "Constructed Wetland"

Wetlands for water and wastewater treatment are usually referred to as Constructed Wetlands. Despite some claims to the contrary these wetlands do typically provide the same habitat value as wetlands created specifically for habitat. Treatment wetlands are often characterized by shallow channels filled with dense vegetation with little or no open water to maximize the stem surface area for biological conversion of wastes.

Wetland Creation or "Created Wetland"

EPA definition of wetland creation

Creation is the "construction of a wetland in an area that was not a wetland in the recent past (within the last 100-200 years) and that is isolated from existing wetlands (i.e., not directly adjacent)" (Gwin, et al., 1999). In other words, creation occurs when a wetland is placed on the landscape by some human activity on a non-wetland site (Lewis, 1989). Typically, a wetland is created by excavation of upland soils to elevations that will support the growth of wetland species through the establishment of an appropriate hydrology.[2]

Wetland Enhancement

EPA definition of wetland enhancement

Gwin, et al. (1999) define enhancement as "the modification of specific structural features of an existing wetland to increase one or more functions based on management objectives, typically done by modifying site elevations or the proportion of open water. Although this term implies gain or improvement, a positive change in one wetland function may negatively affect other wetland functions". Lewis (1989) also states that enhancement may also be the alteration of a site to produce conditions that did not previously exist in order to accentuate one or more values of a site. For example, increasing the area of deep water by excavating parts of an emergent wetland may provide more duck habitat (the desired wetland value), but may decrease foraging and cover habitat for young fish.

Enhancement: the manipulation of the physical, chemical, or biological characteristics of a wetland (undisturbed or degraded) site the heighten, intensify, or improve specific function(s) or for a purpose such as water quality improvement, flood water retention or wildlife habitat. Enhancement results in a change in wetland function(s) and can lead to a decline in other wetland function, but does not result in a gain in wetland acres. This term includes activities commonly associated with the terms enhancement, management, manipulation, directed alteration. [3]

Wetland Restoration

EPA definition of wetland retoration

The National Research Council (NRC) , in its 1992 report, Restoration of Aquatic Ecosystems, defined restoration as the "return of an ecosystem to a close approximation of its condition prior to disturbance." That report also states, "The term restoration means the reestablishment of predisturbance aquatic functions and related physical, chemical and biological characteristics (Cairns, 1988; Magnuson et. al., 1980; Lewis, 1989). Restoration is ... a holistic process not achieved through the isolated manipulation of individual elements.

The holistic nature of restoration, including the reintroduction of animals, needs to be emphasized ... Merely recreating a form without the functions, or the functions in an artificial configuration bearing little resemblance to a natural form, does not constitute restoration. The objective is to emulate a natural, self-regulating system that is integrated ecologically with the landscape in which it occurs. Often, restoration requires one or more of the following processes: reconstruction of antecedent physical conditions, chemical adjustment of the soil and water; and biological manipulation, including the reintroduction of absent native flora and fauna..."

The NRC report also advises: "Without an active and ambitious program in the United States, our swelling population and its increasing stresses on aquatic ecosystems will certainly reduce the quality of human life for present and future generations. By embarking now on a major national aquatic ecosystem restoration program, the United States can set an example of aquatic resource stewardship that ultimately will also improve the management of other resource types and will set an international example of environmental leadership."

Gwin, et al. (1999) state that restoration requires knowledge of the wetland type prior to disturbance; restoration has the goal of returning the wetland to that type. However, Lewis (1989) notes that "it is not necessary to have complete knowledge of what those pre-existing conditions were; it is enough to know a wetland of whatever type was there and to have as a goal to return to that same wetland...it is not necessary that a system be returned to a pristine condition." He also finds that restoration may occur when a degraded wetland is returned to a previous condition of ecological functioning, although that previous condition may have also been altered by human activity.

The Society for Ecological Restoration (SER) includes sustainable cultural activities, such as those practiced by indigenous peoples, in its current definition of restoration. SER defines ecological restoration as "the process of assisting the recovery and management of ecological integrity. Ecological integrity includes a critical range of variability in biodiversity, ecological processes and structures, regional and historical context, and sustainable cultural practices."

Restoration: the manipulation of the physical, chemical, or biological characteristics of a site with the goal of returning natural/historic functions to former or degraded wetland. For the purpose of tracking net gains in wetland acres, restoration is divided into:

  • Re-establishment: the manipulation of the physical, chemical, or biological characteristics of a site with the goal of returning natural/historic functions to a former wetland. Re-establishment results in rebuilding a former wetland and results in a gain in wetland acres.
  • Rehabilitation: the manipulation of the physical, chemical, or biological characteristics of a site with the goal of repairing natural/historic functions of degraded wetland. Rehabilitation results in a gain in wetland function, but does not result in a gain in wetland acres.
Restoration, an alternate viewpoint

Because watersheds and systems are highly modified from historical conditions it is not always possible to restore a wetland site to the same conditions that once existed. As such restoration may involve the return of an area that was previous a wetland environment to a wetland with slightly different form or function. For example in areas where river flows no longer fluctuate and flow over bank it may be possible to 'restore' these sites and manage them for habitat using pumps and water control structures. Such an action might not restore exactly the same function as the original wetland but is likely to provide value to wildlife and should be considered as a valid restoration.

Types of Wetlands

EPA brochure and link on what is a wetland. EPA webpage describing different wetland types.

Size of Wetland Projects

There is no standard definition of restoration project size, some of the largest restorations include ongoing work on the Everglades. Another example of a very large restoration project is the Vic Fazio Wildlife Area in California that was originally restored by Ducks Unlimited, Inc. For the purposes of this site it is useful to identify restoration sites as tiny, small, medium and large wetland restoration projects. Stream restoration sites are often measured linearly rather than by the number of acres restored, nevertheless the same catagories apply.

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