On Thursday, January 15, EPAs Office of Research
and Development released the final report,
Connectivity of Streams and Wetlands to
Downstream Waters: A Review and Synthesis of the
Scientific Evidence. The report summarizes
current scientific understanding about the
connectivity of streams and wetlands to
downstream waters. EPA has conducted a thorough
review of the literature more than 1,200
peer-reviewed and published documents on the
scientific evidence regarding the effects that
streams, nontidal wetlands, and open waters have
on larger downstream waters such as rivers, lakes, estuaries, and oceans.
This report represents the state-of-the-science
on the connectivity and isolation of waters in
the United States. It makes five major conclusions, summarized below:
· The scientific literature unequivocally
demonstrates that streams, regardless of their
size or frequency of flow, are connected to
downstream waters and strongly influence their function.
· The scientific literature clearly shows
that wetlands and open waters in riparian areas
(transitional areas between terrestrial and
aquatic ecosystems) and floodplains are
physically, chemically, and biologically
integrated with rivers via functions that improve
downstream water quality. These systems act as
effective buffers to protect downstream waters
from pollution and are essential components of river food webs.
· There is ample evidence that many wetlands
and open waters located outside of riparian areas
and floodplains, even when lacking surface water
connections, provide physical, chemical, and
biological functions that could affect the
integrity of downstream waters. Some potential
benefits of these wetlands are due to their
isolation rather than their connectivity.
Evaluations of the connectivity and effects of
individual wetlands or groups of wetlands are
possible through case-by-case analysis.
· Variations in the degree of connectivity
are determined by the physical, chemical and
biological environment, and by human activities.
These variations support a range of stream and
wetland functions that affect the integrity and
sustainability of downstream waters.
· The literature strongly supports the
conclusion that the incremental contributions of
individual streams and wetlands are cumulative
across entire watersheds, and their effects on
downstream waters should be evaluated within the
context of other streams and wetlands in that watershed.
EPA, along with other federal agencies and
states, can use this scientific report to inform
policy and regulatory decisions, including the
Clean Water Rule being developed by EPA and the
U.S. Army Corps of Engineers. Knowing the
important role the Ecological Society of America
plays in advancing our scientific understanding
of the environment, I wanted to make sure you
were aware of this new report. If you have any
questions, please contact me at 703-347-8623, or
<mailto:[email protected]>[email protected].
You can view and download the report using the
URL, <http://www.epa.gov/ncea>www.epa.gov/ncea.
Jeff
Jeffrey B. Frithsen, Ph.D.
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, SW (8623-P)
Washington, DC 20460
703-347-8623 (office phone)
Physical Office Address/Overnight Deliveries
Two Potomac Yard (North Building), Room N-7741
2733 South Crystal Drive, Arlington, VA 22202
