United States
Environmental Protection
Agency
Office ot Water,
Office of Wetlands,
Oceans and Watersheds (4502 F)
EPA843-F-95-001y
February 1995
Wetlands and Runoff
Since wetlands are typically the
lowest area on the landscape, they
often receive runoff from surrounding
land. Several of the key programs
that address such pollution are
discussed in this fact sheet.
Runoff (sometimes called "stormwater"
or "nonpomt source pollution") is
caused by rainfall or snow melt moving
over and through the ground. Runoff
carries natural and manmade pollut-
ants into low areas such as wetlands,
lakes, streams, and eventually into
ground water. In addition, atmo-
spheric deposition and hydrological
modifications can contribute pollut-
ants to runoff as well as directly into
surface water. The quality or U.S.
wetlands and other water resources is
related to the quality of the environ-
ment contributing to these waters.
However, programs have historically
focused on single goals or small sets of
goals. These programs have succeeded
in identifying and controlling, to some
degree, the larger point sources of
pollution. EPA has expanded its focus
to use an approach that addresses the
interconnections between water
resources and the land, air, and water
environment surrounding the
resources.
Untreated Runoff
Impacts to Wetlands
Untreated runoff from agricultural
land, urban areas, and other sources is
a leading cause of water quality
impairment. Siltation; pollutants;
excess nutrients; and changes to water
flows, such as more frequent inunda-
tion, and increased turbidity, are
responsible for most of the impacts to
wetlands from runoff.
Impacts to wetlands have resulted in
consequences such as changed species
composition, increased pollutant
loadings (e.g., heavy metals), and
replacement of complex wetland
systems with less desired open water.
Modifications of wetlands associated
with some runoff management
practices have resulted in significant
impacts to wetlands. Some impacts
have been particularly tragic, such as
in Kesterson and Stillwater Wildlife
Refuges, where untreated, contami-
nated runoff resulted in mortality and
deformities of wildlife populations,
particularly fish and migratory birds.
Current Status
EPA has developed technical informa-
tion that landowners can use to
protect the many functions of wet-
lands, including water quality im-
provement. An issue paper
highlighting the impacts of stormwater
on wetlands, entitled Natural Wetlands
and Urban Stormwater: Potential
Impacts and Management, is available
through the EPA Wetlands Informa-
tion Hotline (contractor operated).
Other information that can be
obtained includes a guide describing
best management practices to pretreat
stormwater runoff before it enters a
natural wetland (in press). Additional
materials on wetlands protection and
restoration for nonpoint source
benefits will be developed to assist in
implementation of the wetlands and
riparian areas chapter in the CZARA
Management Measures Guidance (see
box on page 2). EPA will continue to
work to address potential opportunities
' and conflicts regarding wetlands and
programs addressing runoff.
For more information, contact the EPA Wetlands Information Hotline
at 1-800-832-7828 (contractor operated).
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