Wetland Management - notes

TERMINOLOGY

The management of wetlands and their use for water quality purposes has resulted in the introduction of a number of terms. Though definitions have not been standardized, recently established definitions for some of these variably applied terms, which we will follow are provided here:

Natural Wetlands - wetlands that do not exist as the result of man's activities.

Wetlands - those areas that are inundated or saturated 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 areas.

Wetland construction - creation of wetlands built specifically for water quality improvement purposes; this typically involves controlled outflow and a design that maximizes certain treatment functions.

Wetland creation - bringing a wetland into existence, whether by accident or intentional, where none existed previously; this includes creation of wetlands for mitigation, habitat, and water quality purposes.

Wetland enhancement - the modification of a natural or created wetland to enhance one or more functions. Enhancement of some wetland functions may negatively affect other functions.

Wetland restoration - the reestablishment of a disturbed or altered wetland as one with greater function or acreage. This may involve reestablishing original vegetation, hydrology, or other parameters to reestablish original or closer-to-original wetland functions.

OVERVIEW

Wetland management generally involves activities that can be conducted with, in, and around wetlands, both natural and man-made, to protect, restore, manipulate, or provide for their functions and values. This discussion of wetland management is divided into issues associated with: 1) natural wetland protection; 2) activities, involving natural wetlands, that are specifically exempted from regulatory requirements; 3) wetland creation and restoration; and 4) wetland construction for water quality improvement.

The values of wetlands are by now well recognized.  This involves not only buffering wetlands from direct human pressures, but also maintaining important natural processes that operate on wetlands from the outside and that may be altered by human activities. Management toward this goal should emphasize long-term sustenance of historical, natural wetland functions and values.

To support the national "no net loss" goal, many activities affecting natural wetlands must be conducted within the framework of government regulatory and other protection programs. Manipulation of natural wetlands, within regulatory jurisdiction, is typically limited to restoration of degraded habitats. The use of natural wetlands for primary water quality treatment of either point or nonpoint pollution sources is inappropriate.

Effective wetland management requires knowledge on a range of wetland subjects. Some of them are as follows:

Factors to consider in setting the designated use and developing a management strategy for a wetland include:

• wetland type and landscape position
• surrounding land uses
• cumulative impacts on the wetland
• vegetation quality
• presence or absence of rare or endangered species
• surface water quality
• wildlife habitat
• cultural values

It is not important to protect only rural or wilderness area wetlands. Urban wetlands can provide multiple values for suburban and city dwellers. The aesthetic and recreational amenities of urban wetlands, and their value as wildlife habitat, can be significant. The capacity of a functional urban wetland in flood control can also be very important.

The Challenge of Protection

The simple goal of protecting a wetland's existing functions can prove to be incredibly complex in the modern landscape. It involves minimizing the human-induced changes affecting the natural forces that shape and sustain a wetland, such as hydrology, climate, biogeochemical fluxes, fire, and species movement. 

Pressures created by human activities include:

• proposals to fragment wetlands with roads and other linear facility crossings
• impacts from recreational uses, including off-road vehicles, especially in residential settings
• impacts from adjacent property owners, or partial or full wetland owners
• incursion of trampling, soil compaction, intense herbivory, and waste loading by domesticated animals, pest control treatments, in urban settings, pedestrian access, mowing, landscaping, solid waste dumping, and domesticated animal activity

Other pressures that affect wetland functions operate less directly and are less apparent. These include:

hydrologic alterations, such as direct surface drainage by ditch-digging, impoundment, de-watering by redirection of contributing land area inflows, de- watering by consumptive use of surface water inflows, de-watering through drawdown of unconfined aquifer from either groundwater withdrawal or stream channelization, making wetter in wet season and drier in dry season by changing both quantity and timing of inflows through placement of impervious surfaces and ditch- digging, and over-inundating by increasing contributing land area and/or increasing yield from a given land area through earthmoving, ditching, drain-tiling, and/or pumping; 

increased sediment, nutrient, organic matter, metals, pathogen and other water pollutant loadings from stormwater runoff and wastewater discharges; 

changes to physical characteristics of inflows, such as temperature, dissolved oxygen, clarity, and pH resulting from a variety of activities; 

atmospheric deposition of pollutants; 

introduction of nuisance and exotic plant and animal species; 

loss of more sensitive wetland plant and animal species due to changes in adjacent land uses; 

loss of surrounding habitat for wetland-dependent species that also require upland habitat; and 

"edge effect" changes in plant and animal species due to changes in light, temperature, and moisture regimes, and from noise, pesticide drift.