Wetlands of the United States

Wetlands of the United States
Name	Wetlands of the United States
Location	United States
Type	diverse wetland ecosystems
Area	historic and current extents variable by region

Wetlands of the United States are diverse ecosystems including marshes, swamps, bogs, fens, and prairie potholes that occur from the Arctic littoral of Alaska to the subtropical estuaries of Florida and the coral atolls of Hawaii. These habitats have shaped landscapes in regions such as the Great Lakes, the Mississippi River Delta, and the Pacific Northwest while supporting species tied to places like Everglades National Park, Chesapeake Bay, and San Francisco Bay. Federal, state, and tribal actors including United States Fish and Wildlife Service, National Oceanic and Atmospheric Administration, Bureau of Land Management, and the National Park Service coordinate with NGOs such as The Nature Conservancy and Ducks Unlimited to study and manage wetlands.

Overview and Definitions

Wetlands are broadly defined in U.S. practice by criteria used by agencies like the United States Army Corps of Engineers and the Environmental Protection Agency that reference hydrology, hydrophytic vegetation, and hydric soils, linking regulatory definitions to statutes such as the Clean Water Act and decisions from the Supreme Court of the United States. Wetland categories used by programs from the National Wetlands Inventory and the International Ramsar Convention inform inventories across landscapes from Alaska tundra to Gulf Coast saltmarshes near New Orleans. Scientific research institutions including the Smithsonian Institution and universities such as University of Florida and University of California, Davis contribute mapping and classification frameworks.

Types and Regional Distribution

Major wetland types include tidal marshes of the Atlantic Coast and Gulf of Mexico, freshwater marshes in the Midwest prairie pothole region, forested swamps in the Southeast such as the Okefenokee Swamp, and peatlands in Minnesota and Maine. The Everglades represent sawgrass marsh and ridge-and-slough systems, while the Sacramento–San Joaquin River Delta and San Francisco Bay Estuary feature tidal wetlands and salt ponds. Alpine wetlands occur in the Rocky Mountains near Yellowstone National Park; coastal wetlands buffer storm surges along New Jersey and Texas; and interior wetlands populate riverine corridors like the Mississippi River and Columbia River basins.

Ecology and Biodiversity

Wetlands support high productivity and provide critical habitat for migratory species using flyways such as the Atlantic Flyway, Mississippi Flyway, and Pacific Flyway. They sustain populations of iconic fauna including American alligator in the Everglades, Whooping crane in Aransas National Wildlife Refuge and Wood stork in Florida. Plant communities include mangroves near Florida Keys National Marine Sanctuary, cattail marshes in the Prairie Pothole Region, and sphagnum-dominated bogs in New England. Wetlands foster invertebrates, fish such as Chinook salmon in Puget Sound tributaries, and amphibians like the California red-legged frog, with ecosystem services recognized by entities including the Intergovernmental Panel on Climate Change and the United States Geological Survey.

Historical and Contemporary Losses

Conversion and drainage driven by agricultural expansion in the 19th century and engineered projects like the Erie Canal and levees along the Mississippi River reduced wetland area, as did urbanization in metropolitan centers including Chicago, Los Angeles, and Houston. The destruction of coastal wetlands accelerated near ports such as New Orleans and Galveston and in energy corridors in Louisiana associated with infrastructure by firms regulated under laws influenced by the Department of the Interior. Historic drainage schemes including those in the Central Valley Project and the Prairie Pothole Region resulted in habitat loss affecting species protected under statutes like the Endangered Species Act.

Conservation, Management, and Restoration

Large-scale restoration initiatives include projects in the Everglades Restoration Plan coordinated among U.S. Army Corps of Engineers, South Florida Water Management District, and State of Florida agencies, tidal marsh restoration in the San Francisco Bay Restoration Authority portfolio, and wetland easements funded through the Natural Resources Conservation Service. Conservation organizations such as Audubon Society, World Wildlife Fund, and The Nature Conservancy partner with tribal nations including the Yurok Tribe and Penobscot Nation on habitat protection. Adaptive management draws on monitoring by the National Oceanic and Atmospheric Administration and modeling from labs at Scripps Institution of Oceanography and Woods Hole Oceanographic Institution to guide reestablishment of hydrology, revegetation, and invasive species control.

Legal and Policy Framework

Key statutes shaping wetland policy include the Clean Water Act Section 404 permit program administered by the United States Army Corps of Engineers with oversight from the Environmental Protection Agency, the Swampbuster provisions of the Food Security Act of 1985 enforced by the United States Department of Agriculture, and protections for species implemented through the Endangered Species Act. International obligations stem from the Ramsar Convention and cross-border initiatives involve bilateral ties with Canada and Mexico under agreements managed by agencies such as the International Joint Commission. Judicial decisions by the Supreme Court of the United States and rulemaking by agencies periodically redefine jurisdictional scope and mitigation requirements.

Threats and Climate Change Impacts

Contemporary threats include sea level rise affecting coastal marshes along Louisiana and Florida, saltwater intrusion into freshwater wetlands in the Chesapeake Bay and Everglades, altered sediment regimes from dam projects on the Missouri River and Columbia River, pollution from agricultural runoff in the Mississippi Basin and urban wastewater in the Great Lakes Basin, and invasive species such as Phragmites australis and Nutria that transform habitats. Climate-driven changes noted by Intergovernmental Panel on Climate Change scenarios project shifts in wetland distribution, carbon sequestration dynamics relevant to United Nations Framework Convention on Climate Change commitments, and increased frequency of storms impacting infrastructure tied to coastal communities like New York City and Miami.

Category:Wetlands of the United States