United States
Environmental Protection Agency
Office of Water
(4501F)
EPA841-F-00-003
March 2000
&EPA Principles for the Ecological Restoration
of Aquatic Resources
Restoration - the return of a degraded ecosystem to a close approximation of its remaining natural
potential is experiencing a groundswell of support across the United States. The number of stream,
river, lake, wetland and estuary restoration projects grows yearly. Current Federal initiatives call for a
wide range of restoration actions, including improving or restoring 25,000 miles of stream corridor;
achieving a net increase of 100,000 acres of wetlands each year; and establishing two million miles of
conservation buffers. Many on-going or completed restoration projects now offer valuable lessons. To
help build on these lessons and promote effective restoration, the Watershed Ecology Team of the Office
of Wetlands, Oceans, and Watersheds has assembled the following list of principles that have been
critical to the success of a wide range of aquatic resource restoration projects. These principles apply to
different stages in the life of a restoration project from early planning to post-implementation
monitoring - and are offered here for use by a wide variety of people and organizations, ranging from
Federal, State, Tribal, and local agencies to outdoor recreation or conservation groups, corporations,
landowners, and citizens' groups.
These principles focus on scientific and technical issues, but as in all environmental management
activities, the importance of community perspectives and values should not be overlooked. The
presence or absence of public support for a restoration project can be the difference between positive
results and failure. Coordination with the people and organizations that may be affected by the project
can help build the support needed to get the project moving and ensure long-term protection of the
restored area. In addition, partnership with stakeholders can also add useful resources, ranging from
money and technical expertise to volunteer help with implementation and monitoring.
Restoration Guiding Principles
Preserve and protect aquatic resources
Restore ecological integrity
Restore natural structure
Restore natural function
Work within the watershed/landscape context
Understand the potential of the watershed
Address ongoing causes of degradation
Develop clear, achievable and measurable goals
Focus on feasibility
Use reference sites
Anticipate future changes
Involve a multi-disciplinary team
Design for self-sustainability
Use passive restoration, when appropriate
Restore native species, avoid non-native species
Use natural fixes and bioengineering
Monitor and adapt where changes are necessary
Watershed Ecology Team, US EPA Office of Wetlands, Oceans and Watersheds
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Restoration Guiding Principles
Preserve and protect aquatic resources. Existing,
relatively intact ecosystems are the keystone for
conserving biodiversity, and provide the biota and other
natural materials needed for the recovery of impaired
systems. Thus, restoration does not replace the need to
protect aquatic resources in the first place. Rather,
restoration is a complementary activity that, when
combined with protection and preservation, can help
achieve overall improvements in a greater percentage of
the Nation's waters. Even with waterbodies for which
restoration is planned, the first objective should be to
prevent further degradation.
Restore ecological integrity. Restoration should
reestablish insofar as possible the ecological integrity of
degraded aquatic ecosystems. Ecological integrity
refers to the condition of an ecosystem particularly
the structure, composition, and natural processes of its
biotic communities and physical environment. An
ecosystem with integrity is a resilient and
self-sustaining natural system able to accommodate
stress and change. Its key ecosystem processes, such as
nutrient cycles, succession, water levels and flow
patterns, and the dynamics of sediment erosion and
deposition, are functioning properly within the natural
range of variability. Biologically, its plant and animal
communities are good examples of the native
communities and diversity found in the region.
Structurally, physical features such as the dimensions of
its stream channels are dynamically stable. Restoration
strives for the greatest progress toward ecological
integrity achievable within the current limits of the
watershed, by using designs that favor the natural
processes and communities that have sustained native
ecosystems through time.
Restore natural structure. Many aquatic resources in
need of restoration have problems that originated with
harmful alteration of channel form or other physical
characteristics, which in turn may have led to problems
such as habitat degradation, changes in flow regimes,
and siltation. Stream channelization, ditching in
wetlands, disconnection from adjacent ecosystems, and
shoreline modifications are examples of structural
alterations that may need to be addressed in a
restoration project. In such cases, restoring the original
site morphology and other physical attributes is
essential to the success of other aspects of the project,
such as improving water quality and bringing back
native biota.
Restore natural function. Structure and function are
closely linked in river corridors, lakes, wetlands,
estuaries and other aquatic resources. Reestablishing
the appropriate natural structure can bring back
beneficial functions. For example, restoring the bottom
elevation in a wetland can be critical for reestablishing
the hydrological regime, natural disturbance cycles, and
nutrient fluxes. In order to maximize the societal and
ecological benefits of the restoration project, it is
essential to identify what functions should be present
and make missing or impaired functions priorities in the
restoration. Verifying whether desired functions have
been reestablished can be a good way to determine
whether the restoration project has succeeded.
Work within the watershed and broader landscape
context. Restoration requires a design based on the
entire watershed, not just the part of the waterbody that
may be the most degraded site. Activities throughout
the watershed can have adverse effects on the aquatic
resource that is being restored. A localized restoration
project may not be able to change what goes on in the
whole watershed, but it can be designed to better
accommodate watershed effects. New and future urban
development may, for example, increase runoff
volumes, stream downcutting and bank erosion, and
pollutant loading. By considering the watershed context
in this case, restoration planners may be able to design a
project for the desired benefits of restoration, while also
withstanding or even helping to remediate the effects of
adjacent land uses on runoff and,nonpoint pollution.
For example, in choosing a site for a wetland restoration
project, planners should consider how the proposed
project may be used to further other related efforts in
the watershed, such as increasing riparian habitat
continuity, reducing flooding, and/or enhancing
downstream water quality. Beyond the watershed, the
broader landscape context also influences restoration
through factors such as interactions with terrestrial
habitats in adjacent watersheds, or the deposition of
airborne pollutants from other regions.
Understand the natural potential of the watershed.
A watershed has the capacity to become only what its
physical and biological setting its ecoregion's
climate, geology, hydrology, and biological
characteristics will support. Establishing restoration
goals for a waterbody requires knowledge of the
historical range of conditions that existed on the site
prior to degradation and what future conditions might
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be. This information can then be used in determining
appropriate goals for the restoration project. In some
cases, the extent and magnitude of changes in the
watershed may constrain the ecological potential of the
site. Accordingly, restoration planning should take into
account any irreversible changes in the watershed that
may affect the system being restored, and focus on
restoring its remaining natural potential.
Address ongoing causes of degradation. Restoration
efforts are likely to fail if the sources of degradation
persist. Therefore, it is essential to identify the causes
of degradation and eliminate or remediate ongoing
stresses wherever possible. While degradation can be
caused by one direct impact such as the filling of a
wetland, much degradation is caused by the cumulative
effect of numerous, indirect impacts, such as changes in
surface flow caused by gradual increases in the amount
of impervious surfaces in the watershed. In identifying
the sources of degradation, it is important to look at
upstream and up-slope activities as well as at direct
impacts on the immediate project site. Further, in some
situations, it may also be necessary to consider
downstream modifications such as dams and
channelization.
Develop clear, achievable, and measurable goals.
Restoration may not succeed without good goals. Goals
direct implementation and provide the standards for
measuring success. Simple conceptual models are a
useful starting point to define the problems, identify the
type of solutions needed, and develop a strategy and
goals. Restoration teams should evaluate different
alternatives to assess which can best accomplish project
goals. The chosen goals should be achievable
ecologically, given the natural potential of the area, and
socioeconomically, given the available resources and
the extent of community support for the project. Also,
all parties affected by the restoration should understand
each project goal clearly to avoid subsequent
misunderstandings. Good goals provide focus and
increase project efficiency.
Focus on feasibility. Particularly in the planning stage,
it is critical to focus on whether the proposed restoration
activity is feasible, taking into account scientific,
financial, social and other considerations. Remember
that solid community support for a project is needed to
ensure its long-term viability. Ecological feasibility is
also critical. For example, a wetlands restoration
project is not likely to succeed if the hydrological
regime that existed prior to degradation cannot be
reestablished.
Use a reference site. Reference sites are areas that are
comparable in structure and function to the proposed
restoration site before it was degraded. As such,
reference sites may be used as models for restoration
projects, as well as a yardstick for measuring the
progress of the project While it is possible to use
historic information on sites that have been altered or
destroyed, historic conditions may be unknown and it
may be most useful to identify an existing, relatively
healthy, similar site as a guide for your project.
Remember, however, that each restoration project will
present a unique set of circumstances, and no two
aquatic systems are truly identical. Therefore, it is
important to tailor your project to the given situation
and account for any differences between the reference
site and the area being restored.
Anticipate future changes. The environment and our
communities are both dynamic. Although it is
impossible to plan for the future precisely, many
foreseeable ecological and societal changes can and
should be factored into restoration design. For example,
in repairing a stream channel, it is important to take into
account potential changes in runoff resulting from
projected increases in upstream impervious surface area
due to development. In addition to potential impacts
from changes in watershed land use, natural changes
such as plant community succession can also influence
restoration. For instance, long-term, post-project
monitoring should take successional processes such as
forest regrowth in a stream corridor into account when
evaluating the outcome of the restoration project.
Involve the skills and insights of a multi-disciplinary
team. Restoration can be a complex undertaking that
integrates a wide range of disciplines including ecology,
aquatic biology, hydrology and hydraulics,
geomorphology, engineering, planning,
communications and social science. It is important that,
to the extent that resources allow, the planning and
implementation of a restoration project involve people
with experience in the disciplines needed for the
particular project. Universities, government agencies,
and private organizations may be able to provide useful
information and expertise to help ensure that restoration
projects are based on well-balanced and thorough plans.
With more complex restoration projects, effective
leadership will also be needed to bring the various
disciplines, viewpoints, and styles together as a
functional team.
Design for self-sustainability. Perhaps the best way to
ensure the long-term viability of a restored area is to
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minimize the need for continuous maintenance of the
site, such as supplying artificial sources of water,
vegetation management, or frequent repairing of
damage done by high water events. High maintenance
approaches not only add costs to the restoration project,
but also make its long-term success dependent upon
human and financial resources that may not always be
available. In addition to limiting the need for
maintenance, designing for self-sustainability also
involves favoring ecological integrity, as an ecosystem
in good condition is more likely to have the ability to
adapt to changes.
Use passive restoration, when appropriate. "Time
heals all wounds" applies to many restoration sites.
Before actively altering a restoration site, determine
whether passive restoration (i.e., simply reducing or
eliminating the sources of degradation and allowing
recovery time) will be enough to allow the site to
naturally regenerate. Many times there are reasons for
restoring a waterbody as quickly as possible, but there
are other situations when immediate results are not
critical. For some rivers and streams, passive
restoration can reestablish stable channels and
floodplains, regrow riparian vegetation, and improve in-
stream habitats without a specific restoration project.
With wetlands that have been drained or otherwise had
their natural hydrology altered, restoring the original
hydrological regime may be enough to let time
reestablish the native plant community, with its
associated habitat value. It is important to note that,
while passive restoration relies on natural processes, it
is still necessary to analyze the site's recovery needs
and determine whether time and natural processes can
meet them.
Restore native species and avoid non-native species.
American natural areas are experiencing significant
problems with invasive, non-native (exotic) species, to
the great detriment of our native ecosystems and the
benefits we've long enjoyed from them. Many invasive
species outcompete natives because they are expert
colonizers of disturbed areas and lack natural controls.
The temporary disturbance present during restoration
projects invites colonization by invasive species which,
once established, can undermine restoration efforts and
lead to further spread of these harmful species.
Invasive, non-native species should not be used in a
restoration project, and special attention should be given
to avoiding the unintentional introduction of such
species at the restoration site when the site is most
vulnerable to invasion. In some cases, removal of non-
native species may be the primary goal of the
restoration project.
Use natural fixes and bioengineering techniques,
where possible. Bioengineering is a method of
construction combining live plants with dead plants or
inorganic materials, to produce living, functioning
systems to prevent erosion, control sediment and other
pollutants, and provide habitat. Bioengineering
techniques can often be successful for erosion control
and bank stabilization, flood mitigation, and even water
treatment. Specific projects can range from the creation
of wetland systems for the treatment of storm water, to
the restoration of vegetation on river banks to enhance
natural decontamination of runoff before it enters the
river.
Monitor and adapt where changes are necessary.
Every combination of watershed characteristics, sources
of stress, and restoration techniques is unique and,
therefore, restoration efforts may not proceed exactly as
planned. Adapting a project to at least some change or
new information should be considered normal.
Monitoring before and during the project is crucial for
finding out whether goals are being achieved. If they
are not, "mid-course" adjustments in the project should
be undertaken. Post-project monitoring will help
determine whether additional actions or adjustments are
needed and can provide useful information for future
restoration efforts. This process of monitoring and
adjustment is known as adaptive management.
Monitoring plans should be feasible in terms of costs
and technology, and should always provide information
relevant to meeting the project goals.
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Notice: This document is intended to promote effective
restoration approaches and practices. This document does
not substitute for the Clean Water Act or EPA's regulations;
nor is it a regulation itself. Thus, it cannot impose
legally-binding requirements on EPA, States, or the
regulated community, and may not apply to a particular
situation based upon the circumstances. EPA retains the
discretion to adopt approaches on a case-by-case basis that
differ from this guidance where appropriate. EPA may
change this guidance in the future.
This publication should be cited as: USEPA, 2000.
Principles for the Ecological Restoration of Aquatic
Resources. EPA841-F-00-003. Office of Water (450IF),
United States Environmental Protection Agency,
Washington, DC. 4pp. To order single, free copies, call 1-
800-490-9198 and request document number EPA841-F-00-
003. The document is also on the OWOW Restoration
Website at http://www.epa.sov/owow/restore/
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