Other Environmental Themes

Wetlands: Master Plumbers

For most of this country's history, the federal government actively promoted the drainage of swamps, bogs, and marshes, regarding them as nuisances in general and mosquito breeding grounds in particular. Under the Swamp Land Acts, starting in the mid-1800s, the federal government gave the states nearly 65 million wetland acres for "reclamation" and conversion to other uses. The practice of filling in wetlands abated later in this century with the passage of the Clean Water Act and other policies that recognized the value of these soggy zones in sustaining wildlife, safeguarding water supplies and controlling floods. That realization came none too soon, as more than half of this country's original wetlands have been wiped out by human activities. 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. In the Aral Sea basin in Central Asia, for example, wetlands have shrunk by 85 percent, dramatically reducing waterfowl populations.

Wetlands are, in fact, biodiversity havens, providing breeding grounds and habitat for a wide variety of birds, fish and other wildlife. In the United States, they offer refuge to one half of the fish, one third of the bird species and one sixth of the mammal species considered threatened or endangered. Wetlands enhance water quality by filtering out pollutants, sediments and nutrients that overflow a river's banks. They also limit flood damage by providing a buffer that can hold floodwater and delay its return to a river. The economic value of both activities is tremendous. Although estimates have been made in certain cases, no one has attempted a full tally, nor is it likely that such an exercise could ever yield an accurate figure.

In 1989, President George Bush established a "no net loss of wetlands" policy that allowed developers to destroy existing wetlands if they restored previously converted wetlands or created new ones of equal size. The results of that experiment are now in: A 2001 report by the National Research Council concluded that the program has failed to curb the loss of wetlands nationwide because the replacement systems do not function nearly as well as natural ones, assuming they "function" at all.

The history of wetlands restoration and creation is mixed, at best, and we still don't know the extent to which human engineering can revive the remarkable plumbing systems and biodiversity sanctuaries that nature once provided. Even though the effectiveness of mitigation efforts will surely improve over time, protecting existing wetlands should remain the top priority.