Wetlands
Wetlands are some of the most biologically productive natural ecosystems in the world. In fact, they can be compared to tropical rain forests and coral reefs in terms of the diversity of species they support.
Generally, wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface (Cowardin, December 1979). Wetlands generally include swamps, marshes, bogs and similar areas.
Wetlands provide many beneficial uses, including the following:
- Water quality protection
- Flood storage and control
- Groundwater Recharge
- Shoreline erosion control
- Fish and wildlife habitat
- Greenhouse gas control
- Recreation
Wetland plants filter pollutants carried by surface water runoff. A study of the water quality protection benefits of a 2,500 acre wetland in Georgia indicated that it saves $1 million annually in water pollution abatement costs.
Wetlands lower flood heights, reduce erosion of adjacent and downstream lands, and prevent waterlogging of agricultural lands. Once lost, this function can be very costly to replace. A study in Minnesota estimated that cost to replace the natural flood control function of 5000 acres of drained wetlands to be $1.5 million annually.
Wetlands play an active role in the hydrologic cycle by absorbing water and promoting groundwater recharge. One study of a five-acre Florida cypress swamp estimated that if 80 percent of the swamp was drained, available groundwater would be reduced by an estimated 45 percent.
Wetland plants hold soil in place and absorb flood waters, which helps prevent streambank and shoreline erosion. Wetlands reduce the loss of overbank land and reduce the need for costly stabilization repairs.
The Fish and Wildlife Service estimates that 43 percent of federally threatened and endangered species rely directly or indirectly on wetlands for their survival. Wetlands provide valuable habitat needed to support the fish and shellfish industries. Many animals at the base of the food chain, such as the macroinvertebrates that fish feed on, rely on both the live vegetation and the dead plant leaves and stems (detritus) present in wetlands for food.
Wetland plants store carbon dioxide, which helps to control the release of greenhouse gases linked to global warming into the atmosphere. Filling, clearing, and draining wetlands, like the clearing and burning of rain forests, releases this carbon dioxide into the atmosphere.
Wetlands, due to their rich diversity of plant and animal species, are a valuable asset for passive recreation activities such as hiking and birding.
The benefits of wetlands are especially important in urbanizing areas due to their ability to counteract increases in the rate an volume of surface water runoff. Once these benefits are lost, they are difficult to replace. The U.S. Army Corps of Engineers and the Virginia Department of Environmental Quality regulate wetlands impacts.
In the event that wetland impacts are permitted, wetland mitigation is often required. This requirement has led to the recent emergence of Wetland Mitigation Bank proposals in the County. Mitigation Bank Developers generally establish wetlands in areas able to support them, such as floodplains, and then sell wetland bank credits to developers who are required to mitigate for impacts caused by their development projects.
Mitigation banking is an important tool in managing wetland impacts. However, it is equally important to encourage preservation of these vital resources in order to provide balance for permitted impacts and mitigation. Preservation is the only way to ensure that wetlands remain in areas where their unique functions make them costly and ineffective to replace elsewhere.
Wetland areas should be clearly delineated on all development plans and appropriate permits must be obtained prior to impacting these areas. For more information on wetland permits, contact:
- United States Army Corps of Engineers 703-221-6967
- Virginia Department of Environmental Quality - Virginia Water Protection Program 804-698-4375
- Virginia Marine Resources Commission 757-247-8063
- Visit EPA's Office of Wetlands, Oceans, and Watersheds Web site. The information summarized on this Web page was taken in part from the Watershed Academy Training Module on Wetlands Functions and Values
Date Last Modified: 02/09/2006