United States
Environmental Protection
Agency
Office of Water
Office of Wetlands,
Oceans and Watersheds (4502T)
EPA843-F-01-002C
March 2002
Wetlands are
considered valuable
because they clean
the water, recharge
water supplies,
reduce flood risks,
and provide fish and
wildlife habitat. In
addition, wetlands
provide recreational
opportunities,
aesthetic benefits,
sites for research and
education, and
commercial fishery
benefits.
Long regarded as wastelands, wetlands are now recognizer1 —
important features in the landscape that provide numeroi
beneficial services for people and for fish and wildlife.
Some of these services, or functions, include protecting
and improving water quality, providing fish and wildlife
habitats, storing floodwaters, and maintaining surface
water flow during dry periods. These beneficial services,
considered valuable to societies worldwide, are the
result of the inherent and unique natural characteristics
ofwetlands.
Functions Versus Values
Wstland functions include water quality
improvement, floodwater storage, fish
and wildlife habitat, aesthetics, and biological
productivity. The value of a wetland is an
estimate of the importance or worth of one or
more of its functions to society. For example, a
value can be determined by the revenue
generated from the sale offish that depend on
the wetland, by the tourist dollars associated
with the wetland, or by public support for
protecting fish and wildlife.
Although large-scale benefits of functions can
be valued, determining the value of individual
wetlands is difficult because they differ widely
and do not all perform the same functions or
perform functions equally well. Decision-
makers must understand that impacts on
wetland functions can eliminate or diminish the
values ofwetlands.
Water storage. Wetlands function
like natural tubs or sponges,
storing water and slowly releasing
it. This process slows the water's
momentum and erosive potential,
reduces flood heights, and allows
for ground water recharge, which
contributes to base flow to
surface water systems
during dry periods.
Although a small wetland
might not store much water, a
network of many small wetlands can
store an enormous amount of water.
The ability ofwetlands to store
floodwaters reduces the risk of costly
property damage and loss of life—benefits that
have economic value to us. For example, the
U.S. Army Corps of Engineers found that
protecting wetlands along the Charles River in
Boston, Massachusetts, saved $17 million in
potential flood damage.
Water filtration. After being slowed by a
wetland, water moves around plants, allowing
the suspended sediment to drop out and settle
to the wetland floor. Nutrients from fertilizer
application, manure, leaking septic tanks, and
municipal sewage that are dissolved in the
water are often absorbed by plant roots and
microorganisms in the soil. Other pollutants
stick to soil particles. In many cases, this
filtration process removes much of the water's
nutrient and pollutant load by the time it leaves
a wetland. Some types ofwetlands are so good
at this filtration function that environmental
managers construct similar artificial wetlands
to treat storm water and wastewater.
Red-osier dogwood
-------
Biological productivity. Wetlands are some of
the most biologically productive natural
ecosystems in the world, comparable to tropical
rain forests and coral reefs in their productivity
and the diversity of species they support.
Abundant vegetation and shallow water provide
diverse habitats for fish and wildlife. Aquatic
plant life flourishes in the nutrient-rich
environment, and energy converted by the
plants is passed up the food chain to fish,
waterfowl, and other wildlife and to us as well.
This function supports valuable commercial fish
and shellfish industries.
D\D VOL) IL
The Great Flood of 1993 in the upper Mississippi River Basin caused billions
of dollars in property damage and resulted in 38 deaths. Historically,
20 million acres of wetlands in this area had been drained or filled, mostly
for agricultural purposes. If the wetlands had been preserved rather than
drained, much property damage and crop loss could have been avoided.
In 1991 wetland-related ecotourism activities such as hunting, fishing, bird-watching, and
photography added approximately $59 billion to the national economy.
According to the Pacific Coast Federation of Fishermen's Associations, almost $79 billion per
year is generated from wetland-dependent species, or about 71 percent of the nation's
entire $111 billion commercial and recreational fishing industry in 1997.
An acre of wetland can store 1-1.5 million gallons of floodwater.
Up to one-half of North American bird species nest or feed in wetlands.
Although wetlands keep only about 5 percent of the land surface in the conterminous United
States, they are home to 31 percent of our plant species.
Seventy-five percent of commercially
harvested fish are wetland-dependent.
Add shellfish species and that
number jumps to 95 percent.
American Avocet
The Wetland Fact Sheet Series
Wetlands Overview
Types of Wetlands
Functions & Values of Wetlands
Threats to Wetlands
Wetland Restoration
Funding Wetland Projects
Wetland Monitoring & Assessment
Sustainable Communities
Volunteering for Wetlands
Teaching about Wetlands
For more information, visit www.epa.gov/owow/wetlands.
On the Internet
Ecosystem Valuation www.ecosystemvaluation.org
Economic Valua tion of Wetlands www. ramsar.org/lib_val_e_index. htm
In Print
Restoration, Creation, and Recovery of Wetlands: Wetland Functions, Values, and Assessment, R.P. Novitzki, R.D. Smith,
and J.D. Fretwell. United States Geological Survey Water Supply Paper 2425. Available on-line at http://water.usgs.gov/
nwsum/WSP 2 4 2 5/functions. html.
Technical Aspects of Wetlands: Wetland Hydrology, Water Quality, and Associated Functions, Virginia Carter. United States
Geological Survey Water Supply Paper 2425. Available on-line at http://water.usgs.gov/nwsum/WSP2425/hydrology.html.
Wetlands Functions and Values. Visit the North Carolina State University Water Quality Group's on-line informational
database, WATERSHEDSS, at http://h2osparc.wq.ncsu.edu/info/wetlands/funval.html.
------- |