Wetlands encompass an enormously diverse range of areas, with different water regimes, dominant plant species, and sediment or soil characteristics. However, all wetlands have water present for a significant period of time and plants adapted to their wet conditions. Wetlands encompass large areas along the shores of lakes and small prairie potholes found in the north central United States. Neither exclusively aquatic nor terrestrial, wetlands are in the zone between permanently wet and normally dry environments. While the crucial value of wetland ecosystems is widely recognized today, in the past they were considered swampland to be drained or filled in for agricultural and other uses. In the United States, some 117 million acres (47.4 million hectares) of wetlands, half the original acreage, have been lost to such conversion by the mid-1980s.

Modern society recognizes that wetlands play a major role in providing habitats for numerous plants and animals, including...