MARSHES are periodically saturated,

flooded, or ponded with water and characterized by herbaceous (non-woody) vegetation

adapted to wet soil conditions. Marshes are

further characterized as tidal marshes

and non-tidal marshes.

Tidal (coastal) marshes occur along

coastlines and are influenced by tides

and often by freshwater from runoff,

rivers, or ground water. Salt marshes

are the most prevalent types of tidal

marshes and are characterized by salttolerant plants such as smooth cordgrass, saltgrass, and glasswort. Salt

marshes have one of the highest rates of

primary productivity associated with

wetland ecosystems because of the

inflow of nutrients and organics

from surface and/or tidal water.

Tidal freshwater marshes are located

upstream of estuaries. Tides influence

water levels but the water is fresh.

The lack of salt stress allows a

greater diversity of plants to thrive.

Cattail, wild rice, pickerelweed,

and arrowhead are common and

help support a large and diverse

range of bird and fish species,

among other wildlife.

Nontidal (inland) marshes are

dominated by herbaceous plants

and frequently occur in poorly

drained depressions, floodplains,

and shallow water areas along the

edges of lakes and rivers. Major

regions of the United States that

support inland marshes include the

Great Lakes coastal marshes, the

prairie pothole region, and the

Florida Everglades.

Do you think all wetlands are the same? Think again. Each

wetland differs due to variations in soils, landscape,

climate, water regime and chemistry, vegetation, and

human disturbance. Below are brief descriptions of the

major types of wetlands found in the United States

organized into four general categories: marshes, swamps,

bogs, and fens.

! Freshwater marshes are characterized by

periodic or permanent shallow water, little

or no peat deposition, and mineral soils.

They typically derive most of their water

from surface waters, including floodwater

and runoff, but do receive ground water

inputs.

! Wet meadows commonly occur in poorly

drained areas such as shallow lake basins,

low-lying depressions, and the land

between shallow marshes and upland areas.

Precipitation serves as their primary water

supply, so they are often dry in the summer.

! Wet prairies are similar to wet meadows

but remain saturated longer. Wet prairies

may receive water from intermittent

streams as well as ground water and

precipitation.

! Prairie potholes develop when snowmelt

and rain fill the pockmarks left on the

landscape by glaciers. Ground water input

is also important.

! Playas are small basins that collect rainfall

and runoff from the surrounding land.

These low-lying areas are found in the

Southern High Plains of the United States.

! Vernal pools have either bedrock or a hard

clay layer in the soil that helps keep water

in the pool. They are covered by shallow

water for variable periods from winter to

spring, but may be completely dry for most

of the summer and fall.

Reddish egret

United States Office of Water EPA 843-F-01-002b

Environmental Protection Office of Wetlands, September 2001

Agency Oceans and Watersheds (4502T)

Many vernal pools fill with water in

fall or spring.

Dave Davis

Freshwater marshes, like this one in

Sequoia National Park, are dependent

on rainfall, runoff, and seasonal

flooding for their water supplies.

Leigh Dunkelberger

The Vernal Pool Association

Farmland surrounds these prairie

potholes in Nebraska.
SWAMPS are fed primarily by surface water

inputs and are dominated by trees and

shrubs. Swamps occur in either freshwater or

saltwater floodplains. They are characterized by

very wet soils during the growing season and

standing water during certain times of the year.

Well-known swamps include Georgia’s Okefenokee Swamp and Virginia’s Great Dismal

Swamp. Swamps are classified as forested,

shrub, or mangrove.

Forested swamps are found in broad

floodplains of the northeast, southeast, and

south-central United States and

receive floodwater from nearby

rivers and streams. Common

deciduous trees found in these areas

include bald cypress, water tupelo,

swamp white oak, and red maple.

Shrub swamps are similar to

forested swamps except that

shrubby species like buttonbush and

swamp rose dominate.

Mangrove swamps are coastal wetlands characterized by salt-tolerant trees, shrubs, and other

plants growing in brackish to saline tidal waters.

These tropical and subtropical systems have a

North American range that extends from the southern tip of Florida along the Gulf Coast to Texas.

BOGS are freshwater wetlands characterized

by spongy peat deposits, a growth of evergreen trees and shrubs, and a floor covered by a

thick carpet of sphagnum moss. These systems,

whose only water source is rainwater, are

usually found in glaciated areas of the northern

United States. One type of bog, called a

pocosin, is found only in the

Southeastern Coastal Plain.

On the Internet

EPA’s Wetland Home Page contains information and pictures on several

types of wetlands...................................................................................................... www.epa.gov/owow/wetlands/types

Types of Wetlands and Their Roles in the Watershed, part of North Carolina

State University’s WATERSHEDSS ...................................................... h2osparc.wq.ncsu.edu/info/wetlands/types3.html

Wetlands of the United States from the USGS Northern Prairie

Wildlife Research Center ........................................................... www.npwrc.usgs.gov/resource/1998/uswetlan/types.htm

Prairie Potholes ...................................................................................... www.greatplains.org/resource/1999/ppjv/ppjv.htm

In Print

Wetlands. 3rd Edition. W.J. Mitsch, and J.G. Gosselink. 2000. John Wiley & Sons, Inc. New York, NY.

In Search of Swampland: A Wetland Sourcebook and Field Guide. R.W. Tiner, 1998. Rutgers University Press, Piscataway, NJ.

Adopting a Wetland—A Northwest Guide. S. Yates. 1989.

FENS are ground

water-fed peatforming wetlands

covered by grasses,

sedges, reeds, and

wildflowers. Willow

and birch are also

common. Fens, like

bogs, tend to occur in

glaciated areas of the

northern United

States.

The Wetland Fact Sheet Series

Wetlands Overview Funding Wetland Projects

Types of Wetlands Wetland Monitoring & Assessment

Functions & Values of Wetlands Sustainable Communities

Threats to Wetlands Volunteering for Wetlands

Wetland Restoration Teaching about Wetlands

For more information, visit www.epa.gov/owow/wetlands.

American Avocet

Bog ecosystems

support

cranberries,

blueberries, and

carnivorous

plants like the

pitcher plant.

Trees found in

swamps are sometimes buttressed at

the base, which

helps anchor them in

the saturated soils.

Dave Davis

U.S. Army Corps of Engineers

Forested swamps serve a

critical role in the watershed by reducing the risk

and severity of flooding

to downstream areas.