some plants such as arrow arum and swamp rose-mallow are "obligate" wetland plants (growing only in wetlands), while "facultative" wetland plants such as pawpaw and sycamore trees can grow on flood plains away from wetland soils
(click on images for larger versions)
Technically, wetlands are "areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.""1 Wetlands do not have to have standing water 12 months of the year, but soils and plants must reflect the frequently-high water table.
wetland at mouth of Neabsco Creek, at Leesylvania State Park
wetlands at mouth of Pohick Creek and Accotink Creek
Source: US Fish and Wildlife Service National Wetlands Inventory, Wetlands Mapper
Virginia wetland statistics (calculated at the end of the 1970's):2
1 million acres of wetlands of all types
72% are palustrine vegetated wetlands ("palustrine" wetlands are located in fields/forests and on the edge of streams - but not adjacent to large lakes or on the edge of tidal waters)
23% are estuarine wetlands ("estuarine" wetlands are associated with tidal waters, east of the Fall Line)
72% of all wetlands are located in the Coastal Plain
22% of all wetlands are located in the Piedmont
6% of all wetlands are in the other physiographic provinces
Wetlands are now a valued ecological resource in Virginia - but in the 400 years of settlement after Jamestown, 42% of the natural wetlands were drained or filled for agriculture, industrial facilities, roads/ports, and urban/suburban development. In particular, estuarine and palustrine vegetated wetlands were lost. At the same time, new natural beaver bonds and artificial construction of farm ponds and reservoirs created an increase in open water areas.3
Today, government policy is to ensure "no net loss" of wetlands, ideally by avoiding alteration of a natural wetland. As described by the Environmental Protection Agency:4
Projects that destroy even tiny wetland areas are required to mitigate the loss by creation of artificial wetlands of an equivalent type. Destruction of a forested wetland requires two acres of new forested wetland for every acre destroyed, while destruction of a scrub-shrub wetland must be mitigated by a 1.5-to-1 ratio.
The Virginia Department of Environmental Quality (DEQ) issues Virginia Water Protection Permits for non-tidal wetlands, and the Virginia Marine Resources Commission (VMRC) manages changes to tidal wetlands. The Federal government authority to regulate wetlands is based on Section 404 of the Clean Water Act, processed by the US Army Corps of Engineers. Section 404 requires a permit before dredged or fill material may be discharged into waters of the United States.
Source: US Fish and Wildlife Service, MidAtlantic Wetlands: A Disappearing Natural Treasure
According to the state summary of the National Water Summary on Wetland Resources (U.S. Geological Survey Water-Supply Paper 2425):5
estuarine wetlands on eastern side of Eastern Shore
Source: US Fish and Wildlife Service, National Wetlands Inventory, Wetlands Mapper
Virginia still has 144 named swamps, but has lost over 40% of its wetlands since the 1780's. The "lost" acres have been converted into upland (filled in with dirt and other materials) or open water (through dredging or erosion).
The Army Corps of Engineers issues permits for dredging and filling wetlands. These permits are required by Section 404 of the Clean Water Act (Public Law 95-217). A list of public notices being considered by the Norfolk District will almost always include a few announcements about 404 permit applications in Virginia.
The Federal government's claim to authority to control even minor land disturbance is based on the constitutional authority to regulate navigable waterways (including Section 10 of the Rivers and Harbors Act passed in 1899). As described Section 320.2 of the Code of Federal Regulations:6
"Isolated wetlands" that are not directly connected to the navigable waters of the United States (such as a vernal pool in a forested area, away from a stream) are excluded from Federal regulation, but modification of isolated wetlands still requires a state permit from DEQ. Also excluded from Section 404 Federal regulation are many farming/forestry activities.
Mathews County wetlands
Source: US Fish and Wildlife Service, National Wetlands Inventory
Filling wetlands will change the way water runs off into the navigable streams, such as the James River. The Corps is notorious in some quarters for its philosophy of building structures rather than preserving the natural environment, even when the economic (as well as environmental) costs of a waterway or dam exceed the benefits - but according to the Federal rules of the game, it's the Corps that determines what permits to approve or reject.
There is a key difference between the definitions of "biological" and "jurisdictional" wetlands. Wetland protection became a political issue in the Bush/Quayle administration, with claims that the "no net loss" commitment was a fraud because the definition of wetland was being narrowed to just areas with standing water throughout the year. The Federal agencies, including the Department of Agriculture farming bureaus, the Department of the Interior wildlife conservation bureaus, and the Environmental Protection Agency, were unable to adopt one standard manual for mapping wetlands consistently.
It requires professional judgment to determine the exact edge of a wetland. "Delineation" of a wetland boundary is not a cookbook process that any landowner can do. The Corps definition of wetlands recognizes that areas that are dry for much of the year can still be classified as wetlands. The Corps specialists will conduct on-site reviews to determine exactly where the regulations require a permit based on the vegetation, soil, and hydrology.
So cutting down the cattails to disguise the existence of a wetland won't work. The Corps advises landowners to request consultation if , in the Corps definition, an:7
Bay 101: Wetlands from Chesapeake Bay Program on Vimeo