Fewer Marshes + More Man-Made Ponds = Increased Wetlands - New York Times

"WASHINGTON, March 30 — In the bog of the federal regulatory code, a wetland is defined as a marshy area of saturated soils and plants whose roots spend part of their lives immersed in water. In the Interior Department's periodic national surveys, a wetland is defined, more or less, as wet.

Traditional tidal, coastal and upland marshes count, but so do golf course water hazards and other man-made ponds whose surface is less than 20 acres.
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A net total of 523,500 acres of swamps and tidal marshes had been lost, but the Fish and Wildlife Service measured gains of 715,300 acres of shallow-water wetlands, or ponds. According to the report's author, Tom Dahl, those can be 20 to 30 feet deep."