Marshes are wetlands dominated by emergent herbaceous vegetation and are often found in association with other wetland types, such as forested swamps and bogs. Marshes are habitat for a large variety of plants, fish, salamanders, frogs, turtles, mammals, and birds, and are especially important for many species considered rare in West Virginia.

In West Virginia, marshes are typically found in natural depressions, around artificial impoundments, and where water flows are impeded by drainage obstructions in low-lying areas, such as an old beaver dam. Because of the rugged topography, marshes cover only about 14,000 acres of West Virginia, a relatively small proportion compared to other states.

Marshes occur throughout the state, with large marsh areas in Canaan Valley and along the Meadow River in Greenbrier County. Other marshes occur at Green Bottom Swamp in Cabell County, Short Mountain Wetlands in Hampshire County, Altona-Piedmont Marsh in Jefferson County, and Cranesville Swamp in Preston County.

Construction that impeded natural drainage and deforestation of swamps has increased marsh acreage in parts of West Virginia. However, marshes have been destroyed by many human activities, including draining, ditching, filling, and impounding. For example, marshes on marl deposits in Berkeley and Jefferson counties, which support many rare species, have been reduced from about 2,700 acres in 1750 to fewer than 300 acres at present. Conservationists have been working to protect marshes by setting them aside as nature preserves, restoring areas impacted by drainage attempts, and increasing public awareness of their importance to wildlife.