NANFA-- Ecological Importance of Geographically Isolated Wetlands

Christopher Scharpf (
Tue, 11 Jun 2002 20:09:14 GMT


The U.S. Fish and Wildlife Service released a report today on the ecology
and extent of geographically isolated wetlands of the United States. The
report is the first in a planned series of ecological reports, with maps,
about important types of wetlands.

"People increasingly realize how important geographically isolated
wetlands in their areas are to wildlife conservation and a healthy
environment," said Steve Williams, Director of the U.S. Fish and Wildlife
Service. "The Prairie Pothole region, known as America's duck factory,
represents only one of many different landscapes nationwide that provide
invaluable wildlife habitat in their isolated wetlands. The report we are
issuing today provides a solid introduction to the basic ecology and
geography of these irreplaceable resources."

"In desert areas, isolated wetlands provide vital fresh water oases for
wildlife and function as stepping stones for migrating birds. Their
isolation has promoted the evolution of unique plant and animal life that
is specially adapted to these habitats," Williams explained. "Isolated
wetlands are also vital for human well being. Many of them contribute
important subsurface water flows to other wetlands and streams. In
areas like the Prairie Pothole region, these wetlands also store rainwater,
which reduces flooding and recharges groundwater supplies, in addition
to providing habitat for wildlife."

Isolated wetlands, which the report defines are "wetlands with no
apparent surface water connection to perennial rivers and streams,
estuaries, or the ocean," have no surface water outlet. Because they are
completely surrounded by uplands, they are vulnerable to changes in
surrounding land use practices.

The report describes 19 types of isolated wetlands, such as the Nebraska
Sandhills wetlands, Delmarva potholes, and Carolina Bay wetlands, and
provides ecological profiles of their fish and wildlife conservation
values. A series of computer-generated maps in the report depict the
potential extent of geographically isolated wetlands in each of 72 selected
study areas, designed to provide a cross-section of national conditions.
The report indicates that geographically isolated wetlands appeared to be
most extensive and abundant in subhumid to arid regions of the country
where precipitation averages less than 24 inches a year, and in Florida's
karst topography. More than half of the identified wetland acreage in
eight of the 72 study areas - located in Nevada, Washington, Texas,
Indiana, Wyoming, South Dakota, and Nebraska - was designated as

The report does not address the regulation of isolated wetlands and the
maps do not depict isolated wetlands for jurisdictional purposes.

The report and maps are available on the Internet at
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