There is a divergence of opinion on the issue of wetland restoration and creation. The optimists maintain that humans can go far toward reviving and building systems that emulate nature to a large extent, while pessimists tend to dwell on the shortcomings of these attempts. There is some validity to both perspectives, and on one point most observers seem to agree: Getting the hydrology right is the first step toward achieving any measure of success. That means having the presence of water when you need it, where you need it, and at the right elevation depending on the time of year. Achieving this goal requires a careful sculpting of the land - creating basins with the proper grade to hold water at the right place and level.
"Things go right when you get the water right," says hydrologist Donald Hey, who directs the Des Plaines River Wetlands Demonstration Project in northern Illinois, among other ventures. "Soil chemistry changes in response to the presence or absence of water," he adds. "The soils will follow the hydrology, and the plants will follow the hydrology and soils. If you can control the invasion of weedy plants, you could have a high-quality wetland."
William Mitsch - an Ohio State University wetlands ecologist who is overseeing the research wetlands built on campus along the Olentangy River - explains that a rigid, engineering-style philosophy doesn't work in the design of natural systems because "we're still not smart enough to know exactly how nature works." Mitsch recommends finding a site with suitable hydrology where wetlands previously existed or near existing wetlands. Rather than "overengineer" the system with an elaborate network of artificial channels and rectangular basins, the system should rely on natural water flows to the full extent possible. Floods are to be expected rather than feared.
"The idea of a so-called designer wetland, where you specify exactly what kinds of vegetation you want, is really just gardening, and we can't afford to do that on a large scale," Mitsch says. "At some point, we have to let nature have the major role, which is what we call self-design." Patience is then needed, as wetlands do not become functional overnight. "It could take years to establish the right mix of water, plants, soil nutrients, and wildlife," he adds. "Strategies that try to short-circuit ecological succession or overmanage it are doomed to failure."
Hydrologist Hey, who also endorses the policy of self-design, squarely places himself within the "optimist" camp on the restoration divide. "We can restore wetlands and replicate their functions, although maybe not in minute details," he says. "But in time, perhaps those details can be achieved. And just by setting the land aside and making a commitment to wetlands, we have the opportunity to go back and try again, even if we initially fail."
More than half of the wetlands in the United States have been lost to human activities and as much as 90 percent of the wetlands in states such as California and Ohio have been wiped out.