- Wetland restoration—the return of a wetland to a close approximation of its condition prior to disturbance, including reestablishment of its predisturbance aquatic functions and related physical, chemical, and biological characteristics.
- Creation—the construction of a wetland in an area that was not a wetland within the past 100 to 200 years and is isolated from other wetlands.
- Enhancement—the modification of one or more structural features of an existing wetland to increase one or more functions based on management objectives. Enhancement, while causing a positive gain in one function, frequently results in a reduction in another function.
- Replacement or reallocation—activities in which most or all of an existing wetland is converted to a different type of wetland, and has the same drawback as enhancement.
Each of these approaches has benefits and drawbacks.
Private Initiatives
More than 75% of the wetlands in the United States are privately owned. Therefore, the protection and restoration or enhancement of most wetlands will be done on private property. A number of government programs, both regulatory and voluntary, exist to foster wetland protection, and some foster both restoration and enhancement. Many have been successful, but government cannot do it all. Some of the most successful wetland programs and projects are the result of private initiatives. Frequently, private organizations form partnerships with landowners to buy, lease, or create easements paid for with private, or a mix of private and public, funds.
Organizations such as the Nature Conservancy, Ducks Unlimited, the Audubon Society, the Chesapeake Bay Foundation, and hundreds of others are working with private landowners, corporations, local communities, volunteers, and federal and state agencies in innovative projects to protect and restore wetlands. For example, the Nature Conservancy has two wetland restoration projects on the Illinois River, Spunky Bottoms and Emiquon, that aim to return more than 8,500 acres of farmed land to their original wetland state.
In another example, Ducks Unlimited is working with the National Resource Conservation Service to implement the Wetland Reserve Program in the Mississippi Alluvial Valley, which historically comprised twenty-four million acres of hardwood bottom stretching from southern Illinois to Louisiana. Since the partnership formed, 8.7 million hardwood seedlings have been planted on 29,000 acres in Arkansas, Louisiana, and Mississippi.
Constructed Wetlands
One growing source of constructed wetlands is waste-water treatment. Constructed wetland treatment systems are designed and constructed to use the natural processes involving wetland soils, vegetation, and their associated microbes to assist with the treatment of waste-water. They are designed to take advantage of many of the same processes that occur in wetlands but in a more controlled manner. While some of these systems are operated solely to treat wastewater, others were designed with the multiple objectives of using treated wastewater effluent as a source of water for the creation or restoration of wetland habitat for wildlife and environmental enhancement. The cost is often competitive with traditional wastewater treatment alternatives. The primary drawback is that they are land intensive; large land tracts are not always available at affordable prices.
There are two general types of constructed wetland treatments: subsurface flow systems and free water surface systems. Both types are usually constructed in basins or channels with a natural or constructed subsurface barrier to limit seepage. The subsurface flow systems create subsurface flow through a permeable medium (soil, sand, gravel, or crushed rock), keeping the water below the surface to minimize odors and other nuisance problems. (See Figure 7.9.) These are also known as rock-reed filters, vegetated submerged bed systems, and root-zone systems. Free water surface systems are designed to simulate natural wetlands, with the water flowing over the soil surface at shallow depths.
Wetlands constructed for wastewater treatment can be found throughout the United States. Alabama, Arizona, California, Colorado, Florida, Illinois, Maryland, Michigan, Mississippi, Nevada, Oregon, and South Carolina are some of the states using constructed wetlands for this purpose.
Marsh construction and wetland rehabilitation as a method of disposing of dredged spoil materials are another growing source of wetland construction. The Army Corps of Engineers has been using dredged material to restore or construct marshes since 1969. Dredged material is placed on shallow bay bottoms to build up elevations to an intertidal level, usually by pumping hydraulically dredged material to the marsh construction site. If the site is exposed to high wind or wave action, protective structures such as riprap breakwaters are built to protect the site. Vegetation can be actively planted or
FIGURE 7.9
A constructed wetland
Restoration of the Florida Everglades
The Everglades is America's premier wetland. It has been designated an International Biosphere Reserve, a World Heritage Site, and a Wetland of International Importance. According to the World Heritage Committee in its report of May 15, 2000, the Everglades is one of two U.S. sites (Yellowstone National Park is the other) on the List of World Heritage in Danger. Figure 7.10 shows how agricultural and industrial activities and urbanization have reduced the Everglades to about half its former size.
The Everglades is part of the South Florida Ecosystem, an 11,000-square-mile region extending from the Kissimmee River near Orlando to the Florida Keys. Originally a wide expanse of wetland, pine forests, man-groves, coastal islands, and coral reefs, today it is one of the nation's most highly populated and manipulated regions. Its freshwater supply comes from rainfall (forty to sixty-five inches per year) in the Kissimmee River Basin and southward, mostly in May through October.
Slow and rain driven, the natural cycle of freshwater circulation feeding the Everglades historically built up in shallow Lake Okeechobee, which averages twelve feet deep and covers about 730 square miles. Thus began the flow of the wide, shallow "river of grass," as it was called by Native Americans. Fifty miles wide in places, one to three feet deep in the slough's center, and only six inches deep elsewhere, it flowed south at a rate of about 100 feet per day across the sawgrass of the Everglades to the mangrove estuaries on the Gulf of Mexico. A six-month dry season followed this flow. During the dry season, water levels gradually drop. The plants and animals of the Everglades are adapted to the alternating wet and dry seasons.
During the past one hundred years, an elaborate system of dikes, canals, levees, floodgates, and pumps has been built to move water to agricultural fields, urban areas, and Everglades National Park. Water runoff from agriculture and urban development have brought excess nutrients into the Everglades, reducing production of beneficial algae and promoting unnatural growth of other vegetation. Ill-timed human manipulation of the water supply has interfered with the natural water cycle, ruining critical spawning, feeding, and nesting conditions for many species.
The Florida legislature has enacted a number of laws to combat the growing water shortage in Florida, including the Everglades. The 1981 Save Our Rivers Act and the 1990 Preservation 2000 Fund authorize the water management districts to buy property to protect water sources, groundwater recharge, and other natural resources. The South Florida Water Management District (SFWMD), the agency that oversees flood protection and water supply, began buying out landowners in the east Everglades area in hopes of retaking more than 200,000 acres of agricultural and residential property at an estimated cost of $2.2 billion. The action is aimed at restoring water flow to the Everglades National Park. For updated status reports on land acquisition efforts, see http://www.evergladesplan.org/pm/progr_land_aquisition.cfm.
In 1998 the Army Corps of Engineers and the SFWMD released their plan for improving Florida's ecological and economic health. This plan covers the entire region and its water problems, and focuses on recovering the major characteristics that defined the "river of grass." Specifically, the plan calls for:
- Reducing the freshwater flows into the Caloosahatchee River and St. Lucie Canal, restoring to the Everglades water now lost to the tide
- Returning the water flow in the Kissimmee River to its former floodplain to achieve a more meandering river system
- Restoring 40,000 acres of marshes for water storage and filtration to remove nutrients prior to water entering the Everglades
- Modifying water deliveries through improved timing and distribution to mimic historic water conditions
FIGURE 7.10
The Everglades, past and present
SOURCE: "The Everglades—Past and Present," in South Florida Ecosystem Restoration: An Overall Strategic Plan and a Decision-Making Process Are Needed to Keep the Effort on Track, U.S. General Accounting Office, 1999 - Reestablishing historic flows and water levels to sloughs feeding into Florida Bay to restore natural estuarine salinity
In 2000 Congress passed the Comprehensive Everglades Restoration Plan, the largest environmental restoration project ever attempted anywhere in the world. Over its thirty-year life, the project will implement the Corps-SFWMD plan. The project will restore critical water flows to the Everglades and ensure adequate water supplies for south Florida cities, communities, and farmers well into the future. The cost of the project will be shared equally between the state of Florida and the federal government.
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