What Is Wetland Restoration?

In its 1992 report, Restoration of Aquatic Ecosystems, the National Research Council defined restoration as the "return of an ecosystem to a close approximation of its condition prior to disturbance." The concept of restoration is further clarified by defining many types of restoration-related activities. These activities, such as creation, reallocation and enhancement, are similar to restoration, but differ in some way from the process of renewing native ecosystems to sites where they once existed.

The holistic nature of restoration, including the reintroduction of animals, is important. 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 Society for Ecological 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."

What Is 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.

What Is 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.

What Is Reallocation or Replacement?

These terms apply to activities in which most or all of an existing wetland is converted to a different type of wetland. For example, changing an emergent wetland to a pond converts the habitat from one wetland type to something quite different.

What Is 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 be legally destroyed, but their loss must be compensated for by the restoration, creation, or enhancement of other wetlands. This strategy should result in "no net loss" of wetlands.

Federal Agency Definitions of Wetland Tracking

The Federal Geographic Data Committee, Wetlands Subcommittee developed definitions for restoration and related activities designed to aid agencies in accurately reporting wetland increases due to their program activities. Many different definitions of these terms have been used by various agencies. The definitions, below, provide standard terminology for the more than 15 agencies involved in wetland restoration, related activities, and/or mitigation.

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.

Establishment: the manipulation of the physical, chemical, or biological characteristics present to develop a wetland that did not previously exist on an upland or deepwater site. Establishment results in a gain in wetland acres.

Enhancement: the manipulation of the physical, chemical, or biological characteristics of a wetland (undisturbed or degraded) site 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.

Protection/Maintenance: the removal of a threat to, or preventing decline of, wetland conditions by an action in or near a wetland. Includes purchase of land or easement, repairing water control structures or fences, or structural protection such as repairing a barrier island. This term also includes activities commonly associated with the term preservation. Protection/Maintenance does not result in a gain of wetland acres or function.

Federal Geographic Data Committee

• US Department of Interior
• US Fish and Wildlife Service
• Bureau of Land Management
• National Park Service
• US Geological Survey
• Bureau of Reclamation
• Office of Surface Mining
• Bureau of Indian Affairs
• US Department of Agriculture
  • Natural Resources Conservation Service
  • Forest Service
• Environmental Protection Agency
• National Marine Fisheries Service (NOAA)
• National Aeronautical and Space Agency
• Department of Energy
• Tennessee Valley Authority
• Army Corps of EngineersDepartment of the Army
• US Marine Corps
• US Navy
• US Air Force
• Office of Management and Budget
• National Capital Planning Commission
• Department of Housing and Urban Development

References

Gwin, S.E., M.E. Kentula, and P.W. Shaffer. 1999. Evaluating the Effects of Wetland Regulation through Hydrogeomorphic Classification and Landscape Profiles. Wetlands 19(3): 477-489.

Lewis, R. R. III 1989. Wetland restoration/creation/enhancement terminology: Suggestions for standardization. Wetland Creation and Restoration: The Status of the Science, Vol. II. EPA 600/3/89/038B. U.S. Environmental Protection Agency, Washington, D.C.

National Research Council. 1992. Restoration of Aquatic Ecosystems: Science, Technology and Public Policy. National Academy Press, Washington, D.C.

Society for Ecological Restoration website