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Fall/Winter 2001 Vol. 1 No. 2

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Wetlands at former Navy Base Homeport, Mobile, Ala. (photo courtesy U.S. Army Corps of Engineers) A Wetland Gained
for a Wetland Lost?

When a National Research Council committee studying wetlands visited a site in southern California, it found a variety of vibrant wetland vegetation and heard from local officials there that several species of wildlife -- including at least one cougar -- had been seen visiting the habitat. This particular wetland, however, was not the work of nature, but rather of human engineering.

It was created by a development com-pany in exchange for a permit to build on nearby natural wetlands. The company graded and contoured part of a regional park, rerouted the flow of water, and removed nonindigenous weeds, planting typical wetland vegetation in their place. The result was a 25-acre wetland that appeared to replicate the natural structure of the 20-acre wetland that was filled.

Up until the 1970s, when the Clean Water Act became law, wetlands were generally considered nothing more than breeding grounds for mosquitoes. Developers regularly filled them in, transforming them into prime real estate for new houses, businesses, and farms. By the 1980s, wetland area in the contiguous United States was half what it had been two centuries earlier. But wetlands, such as marshes, swamps, and bogs, are in fact complex ecosystems that can improve water quality, control floods, diminish droughts, and stabilize shorelines. They also are home to many endangered species.

Inspector on wetlands site with permit applicants (photo courtesy U.S. Army Corps of Engineers) These and other environmental benefits are why the Clean Water Act prohibits wetlands from being filled unless otherwise authorized by a permit issued under Section 404 of the act. Such permits are usually handed out by the U.S. Army Corps of Engineers, which first requires permit applicants to steer clear of, or at least minimize, damage to wetlands. If damage cannot be avoided, the Corps requires the permit holder, or a third party paid by the permit holder, to restore or create nearby wetlands as compensation. In 1989 the White House said the goal of this program should be "no net loss" of wetlands, which federal agencies have taken to mean no loss of acreage or of ecological function.

However, the committee found that, at least as far as ecological function is concerned, the goal was not being met. Although the annual rate of wetland loss has been decreasing in recent years -- perhaps in part because developers have been deterred by the permit process -- the committee found that some required mitigation projects are never undertaken or are not completed. Of those that are, many do not replicate the ecological function of nearby natural wetlands, though the magnitude of loss in function is hard to determine because data are not kept on the ecological status of wetlands that are lost or those that are restored or created.

Insufficient data made it difficult for the committee to determine whether there has been no net loss of wetland acreage, which led it to call on the Corps to create a national database to track the wetland area and functions gained and lost. The Corps also should require permit holders to provide a stewardship organization, such as the Nature Conservancy, with an easement on or title to wetland sites along with sufficient funds for long-term monitoring and maintenance.

It is easier to restore a natural wetland than to create a brand new one, the committee said, adding that rehabilitated or constructed wetlands will be most successful if their functions are considered in terms of their role in the overall surrounding watershed. Strong enforcement by the Corps and other responsible agencies will be needed to ensure that mitigation projects begin on time and meet the design criteria outlined in the permit.

The Corps recently acknowledged what it called "legitimate concerns" raised in the report and issued new guidelines to promote a no-net-loss policy.   -- Bill Kearney

Compensating for Wetland Losses Under the Clean Water Act. Committee on Mitigating Wetland Losses, Board on Environmental Studies and Toxicology and Water Science and Technology Board, Division on Earth and Life Studies (2001, 348 pp.; ISBN 0-309-07432-0; available from National Academy Press, tel. 1-800-624-6242; $49.95 plus $4.50 shipping for single copies).

The study was chaired by Joy Zedler, professor of botany and Aldo Leopold Chair of Restoration Ecology, University of Wisconsin, Madison. Leonard Shabman, professor, Virginia Polytechnic Institute and State University, Blacksburg, served as vice chair. The study was funded by the U.S. Environmental Protection Agency, the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service, and the National Marine Fisheries Service.

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Copyright 2001 by the National Academy of Sciences