Wetlands are areas that are inundated or saturated with water for significant periods during the growing season. They may be adjacent to bodies of open water and subject to flooding, or they may be isolated and receive water from ground sources and precipitation. Plant growth is limited to those species adapted to the lack of oxygen in saturated soils, resulting in distinct wetland vegetation. Wetlands include swamps, marshes, and bogs, as well as man-made features such as shallow ponds and roadside ditches.

Although inventories of West Virginia wetlands are incomplete it is clear that they are uncommon features and unevenly distributed in the state. The total area of wetlands is estimated to comprise less than one-half percent of the state's area, the lowest in the 48 contiguous states. The small area of wetlands is a reflection of the state's mountainous topography.

The largest wetland complex in West Virginia is in Canaan Valley, Tucker County. Other important wetland areas include the upper Meadow River drainage in Greenbrier County, Cranesville Swamp in Preston County, Cranberry Glades in Pocahontas County, and the drainages of Muddelty and Little Beaver creeks in Nicholas County. Additional counties with relatively large areas of wetlands include Randolph, Grant, Barbour, Mason, Fayette, Berkeley, Jefferson, and Hampshire. Numerous small wetlands are located in every county of the state.

Wetlands have many ecological functions and provide many benefits to people. In West Virginia they are likely to be especially important for improving water quality, for wildlife habitat, and as scenic attractions. Wetlands have the capacity to improve water quality by removing nutrients and sediments and may improve the pH of acid mine run-off. In relation to their small area, wetlands contribute disproportionately to the state's biological diversity. About 40 percent of the plants and 20 percent of the vertebrates considered rare by the West Virginia Natural Heritage Program are found primarily in wetlands. Wetlands are the primary habitat for hundreds of common plants and animals and provide resources at some life stage for even more. Wetlands such as Cranberry Glades are among the state's most frequently visited tourist stops.

More than half of the nation's original wetlands have been destroyed, with similar losses in West Virginia, although statistics are lacking. Many of the state's wetlands have been drained for agriculture and filled for industrial and residential development. Others have been flooded behind locks and dams. Large areas of wetland forests have been cleared and converted to pasture. Today, the federal government under the Clean Water Act regulates the state's wetlands, but losses continue. This has been partly compensated for by reversion of agricultural lands following failure of drainage systems and by restoration and construction of wetlands by humans and by beavers.