on inorganic soils Freshwater swamp forest; seasonally flooded forest, wooded swamps; on inorganic soils Peatlands; forest, shrub or open bogs Alpine and tundra wetlands; includes alpine meadows, tundra pools, temporary waters from snow melt Freshwater springs, oases and rock pools Geothermal wetlands Inland, subterranean karst wetlands C—Human-made wetlands Water storage areas; reservoirs, barrages, hydro-electric dams, impoundments (generally > 8 ha) Ponds, including farm ponds, stock ponds, small tanks (generally < 8 ha) Aquaculture ponds; fish ponds, shrimp ponds Salt exploitation; salt pans, salines Excavations; gravel pits, borrow pits, mining pools Wastewater treatment; sewage farms, settling ponds, oxidation basins Irrigated land and irrigation channels; rice fields, canals, ditches Seasonally flooded arable land, farm land United States Wetlands of the United States are classified according to the U.S. Fish and Wildlife Service's National Wetlands Inventory (NWI). In the US, the best known classification systems are the Cowardin classification system and the hydrogeomorphic (HGM) classification system. See also Biome classification Ecological land classification References Wetlands