Despite the constraints on achieving 100 percent success, despite our inadequate knowledge of how to restore wetlands, and despite the problems that will occur during implementation, there is an urgent need to restore large areas of wetland throughout the nation. This need derives from the severe losses of acreage and function that have occurred over the past two centuries (Dahl, 1990), as well as from the potential for substantial human benefits from restored wetlands.
Where wetlands have been drained for agriculture or silvicultural purposes, wetland restoration must be balanced against both the need for agricultural commodities and the landowners' property rights. Because landscape drainage affects both surface and subsurface waters, the halting of drainage may increase crop yields in surrounding lands, while only moderately reducing crop loss in the restored wetland. If restoration of wetland hydrology is shown to cause unreasonable losses in production, then programs to offset personal losses (e.g., CRP, AWRP crop subsidy programs) may be needed.
Perhaps the greatest short-term return can be realized by initially restoring isolated wetlands, wetlands within minimally developed watersheds, and wetlands in the upper reaches of watersheds. Elsewhere, the higher priority may be acquisition of property and/or flood easements in critical parts of the landscape to control hydrology in downstream portions of the landscape before restoration is undertaken. For example, the Russell Sage National Wildlife Refuge System near Monroe, Louisiana, is located in the midreaches of its watershed. Although reforestation of some original bottomland hardwood forest is possible, off-site liabilities related to watershed drainage and flood ''management" limit the potential for restoration of a functional bottomland hardwood forest.
Setting an acreage goal for wetland restoration in the United States requires several assumptions about the extent and condition of damaged wetlands. If only the wetlands along rivers and streams are considered, and if a 100-ft-wide wetland along each side of the waterway is restored, one estimates a potential wetland area of 77,578,758 acres (3.2 million miles, 0.038 mile wide, 640 acres per square mile).