Mitigation Technical
^ Guidance
u.s
9
Chesapeake Bay Wetlands
EPA Report Collection
Information Resource Center
US EPA Region 3
lnhia PA 1Q107
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Mitigation Technical Guidance
—for —
Chesapeake Bay Wetlands
S. Diane Eckles
U.S. Fish and Wildlife Service, Ecological Services, Annapolis, MD
Thomas Barnard
Virginia Institute of Marine Science, Gloucester Pt,, VA
Frank Dawson
Maryland Department of Natural Resources, Annapolis, MD
Tim Goodger
National Marine Fisheries Service, Oxford, MD
Ken Kimidy
U.S. Army, Corps of Engineers, Norfolk District, Norfolk, VA
Anne Lynn
U.S. Soil Conservation Service, Annapolis, MD
Jim Perry
Virginia Institute of Marine Science, Gloucester Pt., VA
Kenneth Reisinger
Pennsylvania Department of Environmental Resources, Harrisburg, PA
Charles Rhodes
U.S. Environmental Protection Agency, Philadelphia, PA
Robert Zepp
U.S. Fish and Wildlife Service, Ecological Services, Annapolis, MD
and the
Chesapeake Bay Wetlands Workgroup
Prepared For
living Resources Subcommittee
Chesapeake Bay Restoration Program
U.S. Environmental Protection Agency
October 1994
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ACKNOWLEDGEMENTS
Appreciation is extended to all those who provided written or verbal
comments to the revision of this document, particularly Dr. Bill Kruczynski,
Dr. Mark Brinson, Dr. Curtis Bohlen, Ms. Barbara D'Angelo, Mr. Bruce
Williams, Ms. Carin Bisland, and Mr. Colin Powers.
Completion of this document in its present form could not have occurred
without the competent technical editing and creative input of Ms. Nina
Fisher.
The authors extend their appreciation to Ms. Betty Wilson, Maryland
Department of Natural Resources, who patiently and expertly typed all
editorial revisions to the final document. Ms. Sandy Koch, U.S. Fish and
Wildlife Service, provided the original artwork for the cover and designed
the document layout.
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Ill
TABLE OF CONTENTS
Acknowledgements «
List of Tables iv
List of Figures iv
Preface 1
Executive Summary : 2
Introduction = 4
Parti: The Mitigation Concept 8
Part II: Compensatory Mitigation Site Selection Criteria:
Ecological Considerations 12
Introduction 12
Wetland Compensatory Mitigation Site
Selection Criteria 14
Variable 1: Identification of wetland ecosystem
hydrologic and structural factors 14
Variable 2: Identification of wetland ecosystem
processes, functions, and values 21
Variable 3: Identification of types of compensatory
mitigation 26
Variable 4: Identification of in-kind or out-of-kind
replacement '• 27
Variable 5: Identification ofon-site or off-site location 31
Variable 6: Identification of compensatory mitigation
timing 32
Variable 7: Identification of lands amenable to compen-
satory mitigation efforts 33
Variable 8: Identification of lands not amenable to
compensatory mitigation efforts 34
Glossary 35
Literature Cited : 37
Selected References 41
Appendix A: Federal Legislation or Related Programs
Affecting Chesapeake Bay Wetlands 42
Appendix B: Applicability of Selected Federal Wetlands
Legislation and Programs to the Chesapeake
Bay Wetlands Mitigation Technical Guidance
Document 47
Appendix C: Technical Summary of Wetland Ecosystem
Processes 49
Appendix D: Atlantic Coast Joint Venture Focus Areas 53
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w
LIST OF TABLES . ^^
W"
Table I. Wetland ecosystem processes.
Table 2. Examples of wetland ecosystem functions, processes, and values.
Table 3. Wetland values and identifying criteria.
LIST OF FIGURES
Figure 1. Conceptualization of the compensatory mitigation process.
Figure 2. Wetland disturbance continuum.
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PREFACE
The wetlands of the Chesapeake Bay watershed are at risk. From the mid-
1950's to the late-1970's, 11,500 acres of coastal wetlands and 54,600 acres of
inland vegetated wetlands were lost within the watershed. Annual losses
during this time in the Bay region averaged over 2/800 acres and national
wetland losses continue at a rate of over 300,000 acres per annum (Tiner
1984,1987). Direct and indirect threats to wetlands and other Bay ecosys-
tems include the quick pace of development and the rapid consumption of
the Bay's natural resources. (U.S. Army Corps of Engineers 1984).
Given the projected level of development within the Bay watershed,
continued loss of some wetlands is unavoidable. The mandate of govern-
ment at all levels should be the minimization of such unavoidable losses
while accommodating the public's needs. Wetland mitigation, in the
broadest sense, is a mechanism that helps achieve this delicate balance
between conflicting interests.
The science of wetland compensatory mitigation has advanced considerably
in the recent past. While "mitigation" has been accepted as a concept in the
environmental impact assessment field for some time, the application of the
concept in regulatory programs such as Section 404 of the Clean Water Act
has been problematic. There is a move towards consensus on the sequenc-
ing of mitigation steps (Kruczynski 1989; Salvesen 1990, U.S. Army Corps of
Engineers, and VS. Environmental Protection Agency 1989). Research
continues into the technical aspects of wetland mitigation but the results to
date reflect the difficulty in offsetting ecological damage due to develop-
ment (Reimold and Cobler 1986; Larson and Neill 1987; Kusler and Kentula
1989a and 1989b).
The purpose of this guidance document is to clarify the concept of wetland
mitigation. At the same time, the document provides a common approach
to mitigation that will allow governmental decisions to rely on a sound
scientific basis. Natural resource interests, developmental groups, and the
general public deserve a wetland regulatory program that is based on
scientific principles and is reasonably predictable.
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EXECUTIVE SUMMARY
Like most wetlands in the United States, those in the Chesapeake Bay
watershed are at risk. Recognizing this risk, the signatories of the 1987
Chesapeake Bay Agreement signed the Chesapeake Bay Wetlands Policy
which focuses on attaining an immediate goal of no net loss of wetlands
and ultimately on achieving a net gain in wetlands. To reach the policy's
goals, regulatory agencies are encouraged to apply the sequential process of
mitigation (avoiding, minimizing, and compensating for wetland impacts)
to all activities adversely affecting wetlands.
This guidance document focuses on the use of mitigation (which includes
compensatory mitigation) to restore and protect wetlands. The first part
provides background information on the sequential process of mitigation.
The rest of the document concentrates on appropriate site selection criteria
fundamental to the development of a compensatory mitigation effort. Since
the guidance in this document relies heavily on the landscape management
approach, use of this information is strongly encouraged outside of the
Chesapeake Bay watershed as well as within its borders.
Although the concept of wetland mitigation was first defined in 1978,
confusion still exists as to what constitutes acceptable and proper mitigation
practices. The primary defining factor in mitigation is that the process is
sequential. That is, every effort should be made to fulfill the first criterion
before moving on to subsequent steps. In addition, the process of mitiga-
tion should be applied in an ecological context by including the landscape
as a significant scale of evaluation. Because cumulative impacts are land-
scape-level phenomena resulting from numerous regulatory and non-
regulatory decisions (Gosselink and Lee 1989), applying mitigation only at
the site-specific level will continue to compromise the ecological integrity of
wetland ecosystems.
The first step in the sequential process of mitigation is avoiding an impact
to a wetland parcel, community, and system by not conducting a specific
activity. In cases where the impact is unavoidable, the second step should
minimize adverse impacts to these areasi>y limiting the degree or magni-
tude of the activity. The third step involves compensating for the impact by
replacing or providing substitute resources or environments.
Historically, applicants viewed the process of compensatory mitigation as a
means to obtain a permit or satisfy a permit condition. In recent years, the
process has evolved to a mechanism to replace both lost wetland acreage
and function. Although exact replication of a wetland community is
unlikely, development and subsequent implementation of compensatory
mitigation plans should utilize the functions, values, and structures of the
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project wetland community as a model. To develop a viable compensatory
mitigation plan, this document proposes the use of eight variables to serve
as both site selection criteria and ecological goals:
Variable 1:
Identification of wetland hydrologic core and structural factors
Variable 2:
Identification of wetland ecosystem processes, functions, and values
Variables:
Identification of compensatory mitigation types
Variable 4:
Identification of in-kind or out-of-kind replacement
Variables:
Identification ofon-site or off-site location
Variable 6:
Identification of compensatory mitigation timing
Variable 7:
Identification lands compatible with compensatory mitigation efforts
Variable 8:
Identification of lands not compatible with compensatory mitigation effort
The use of variables 1,2, and 3 serve as baseline data for the project wet-
land. These data are fundamental sources of information critical for the
replacement of wetland ecosystem properties. Federal and state regulatory
and review agencies should determine the applicability of variables 4
through 8 for each particular case.
Traditionally, mitigation has occurred primarily at the site-specific scale for
the sole purpose of meeting a regulatory obligation. This document greatly
expands the scope of the mitigation process, incorporating the landscape as
a primary consideration in the management of an affected wetland parcel.
The approach espoused in the document suggests evaluating the optimal
means of mimicking the values and functions of the project wetland for use
in the replacement site. Generally, the closer the replacement wetland is to
the project site in terms of geographic location, geomorphic similarity,
physical structure, hydrology, and ecological integrity (as well as other
factors), the more closely it will replicate the project site and meet the
ultimate goals of the sequential process of mitigation.
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INTRODUCTION
In December 1988, the signatories of the 1987 Chesapeake Bay Agreement
signed the Chesapeake Bay Wetlands Policy. The goal of the policy is:
"....to achieve a net resource gain in wetland acreage and function over
present conditions by:
(1) protecting existing wetlands; and
(2) rehabilitating degraded wetlands, restoring former wetlands, and
creating artificial wetlands."
The objectives of the policy include an immediate target of "no-net-loss" and a
long-term target of "net-resource-gain."
"Mitigation" in this document is defined as the sequential process of avoiding,
minimizing, and compensating for impacts to wetlands. This sequential
process is critical to achieve the no-net-loss goal. The principles of mitigation
should apply in any proposed project which may result in adverse impacts to
wetlands. To merge the no-net-loss goals of the Bay policy with the federal and
state regulatory programs in the Chesapeake Bay watershed, the regulatory
agencies are encouraged to apply the sequential process of mitigation to all
activities affecting wetlands.
Regulatory programs at the federal and state levels have limited ability to deal
with wetland issues comprehensively. Wetland ecosystems, the landscapes
surrounding them, and the activities which affect wetland ecosystem processes,
are interactive. The functioning of wetlands and the benefits provided .to
society by wetlands are critically dependent on the interactions among the
wetland ecosystem, land use activities, and the landscape.
The sequential mitigation concept should become an integral part of all govern-
mental decisions, both regulatory and non-regulatory, that affect the functional
integrity of any wetland ecosystem. It is only through such efforts that the
differentiation of "cumulative effects" from "cumulative impacts" can occur
(Preston and Bedford 1988). The identification of both the cumulative impact
sources and the management efforts necessary to control or eliminate such
sources are a function of such a landscape level perspective. Until a landscape
management approach is applied to the living resources of the Chesapeake Bay
(including wetland ecosystems), the no-net-loss and net-resource-gain goals
remain lofty policy expressions rather than realistic policy goals.
Field application of mitigation has not yet achieved the no-net-loss goal due to
many factors including:
1. a lack of definitive scientific data concerning natural wetlands and the
interaction of these wetlands with terrestrial and aquatic communities;
2. the scientific uncertainty of predicting compensatory mitigation results;
3. the lack of unified mitigation guidance, directives, standards, and criteria
among federal, state, and local agencies;
4. a lack of technical and scientific training of agency staff; and
5. a lack of quality control concerning compensatory mitigation projects
(i.e., oversight, tracking, and monitoring).
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To achieve a net resource gain, additional mechanisms are necessary to
complement federal and state regulatory programs. Mitigation, particularly
compensatory mitigation, can not result in a net-resource-gain indepen-
dently. The development and application of initiatives, such as comprehen-
sive incentive programs aimed at wetland conservation, restoration, and
creation, are critical to achieve the net resource gain goal
Wetlands are complex systems and do not generally function in a linear
fashion. By the same token, management directives affecting compensatory
mitigation efforts must take this complexity into consideration. The funda-
mental guiding principle for compensatory mitigation should be repairing
the damage resulting from project impacts on wetland communities. Better
methods are needed to document and account for cumulative impacts which
adversely affect wetlands.
Since federal and state laws, policies, and regulations may exempt some
activities or minimum wetland acreage from specific regulatory require-
ments, wetland ecosystem structure and function within the Chesapeake Bay
drainage basin may become diminished or fragmented by such measures.
Because wetland ecosystems are integral to the functioning of the Chesa-
peake Bay landscape, land use impacts to other ecosystems in the Bay
directly or indirectly affect wetland ecosystems.
Compensatory mitigation cannot fully restore or protect wetlands indepen-
dent of other factors. The guidance in this document therefore, focuses both
on the use of replacement when wetland impact is unavoidable along with
the ecological considerations of replacement activities. Only the replacement
of wetland ecosystems with comparable wetlands is considered. Replacing
wetland features with non-wetland properties will not provide the magni-
tude and diversity of wetland functions and values in the Bay landscape.
The application of the mitigation sequence is an important first step in the
implementation of the immediate no-net-loss goal mandated by the Chesa-
peake Bay Wetlands Policy. Fart I - The Mitigation Concept provides the
necessary background information on the sequential process of mitigation.
Part II - Compensatory Mitigation Site Selection Criteria: Ecological
Considerations emphasizes the ecological complexity associated with
compensatory mitigation and reinforces the sequential process in mitigation.
In the future, as more data become available and compensatory mitigation
efforts are more thoroughly analyzed, the studies may show that avoiding
the impact initially may be the most ecologically and economically sound
decision in the long term. The sequential mitigation concept, as applied to
currently proposed activities, serves as a management tool to minimize
potential negative impacts to the Bay landscape.
Application of any or all of the guidance contained within this document to
federal and state actions outside of the Chesapeake Bay drainage may be
appropriate and is strongly encouraged for application throughout the mid-
Atlantic region. Implementing this for the Chesapeake Bay region may
enhance management decisions concerning living resources across geopoliti-
cal boundaries.
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Several policy and regulatory documents were used as background
informational sources for the development of the mitigation discussion:
1. Chesapeake Bay Wetlands Policy
2. 404(b)(l) Guidelines
3. Section 404 Mitigation Memorandum of Agreement (February 6,1990)
4. VS. Fish and Wildlife Service Mitigation Policy
'5. Council on Environmental Quality Regulations for Implementing
the Procedural Provisions of the National Environmental Policy Act
(NEPA).
A comprehensive literature search of information concerning mitigation
(particularly compensatory mitigation efforts) was not undertaken. Litera-
ture addressing the ecological principles and issues pertinent to compensa-
tory mitigation, however, was selected from several sources, including a
comprehensive annotated bibliography on wetland restoration and creation
(Schneller-McDonald et aL 1990), a review of the scientific status of compen-
satory mitigation efforts (Kusler and Kentula 1989a and 1989b), and relatively
recent symposia, conference, and peer-reviewed journal articles. Literature
references cited in this document as well as additional references that may
provide more in-depth information are also provided.
In addition to the federal legislation and guidance cited above, the follow-
ing federal laws and programs are relevant with respect to the mitigation
process: the Emergency Wetlands Resources Act of 1986, the North
American Waterfowl Management Plan and the Atlantic Coast Joint
Venture, the North American Wetlands Conservation Act, the wetland
conservation provisions of the 1985 Food Security Act, and the 1990 Food,
Agriculture, Conservation, and Trade Act (i.e., the 1985 Farm Bill and 1990
Farm Bill, respectively). Appendix A contains a description of these laws
or programs and Appendix B describes the applicability of these programs
and legislation to this guidance document—~
Currently, this guidance document addresses only a small portion of the
many components associated with mitigation (Figure 1). This document
represents the first in a series of technical guidance materials that will.
eventually be compiled into a mitigation technical guidance handbook.
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STEP1: 2 STEP 2: J
•entifyGoal
("~
e.g.,
hydrological,
structural
and func-
tional
equivalency,
sustainable
systems, etc)
Impact Site
Analysis
a) Conduct
functional
assessment
b) Gather
Baseline data
• Site-specific
• Landscape
• Reference
wetlands
c) Determine
inkind, out-of-
kind or
combination
in-kind/out-of-
Icind
d) Ratio
determina-
tion1
fe
w
STEP 3: S STEP 4: J STEPS: H STEP 6: ^ STEP 7:
Compensatory
Mitigation Site
Analysis
a) Identify
potential
suitable sites
• onsite
• consoli-
dated sites
b) Gather
baseline data
• site-specific
• landscape
c) Identify
mitigation
type suitable
to site(s)
d) Determine if
compensatory
mitigation
site(s) can"
support ratio
area
• identify
other
sites if
necessary2
Site Design
1 1
Monitoring Plan
a) Identify
success
criteria1
b) Include
provisions for
remedial
actions
c) Identify
required
management
d) Identify type
of monitoring,
length
reporting
schedule and
contents, and
who will
conduct
monitoring
e) Use of
reference
wetlands
Develop
Permit
Conditions
Reflecting
Steps 1
through 5
Conduct
Compensatory
Mitigation as
Specified in
Plan
a) Conduct
inspection(s)
of compensa-
tory mitiga-
tion site
under
construction
b) Conduct
permit
compliance
follow-up
•Revise
permit
conditions
if neces-
sary4
n *.J
• Provide
annual
status
report of
compensa-
tory
mitigation1
.-
1 Ratio determinations may be based on quantification of functions/values, potential success/
risk associated with type of mitigation selected, hydrologic dynamics or vegetation structure
to be replaced; temporal losses of functions, both site-specific and in a landscape context
'Selection of additional sites due to hydrological factors, existing or future land use, etc.,
should also be based on the identified goal, and whether in-kind, out-of-kind, or a
combination has been selected to achieve the goal.
1 Success criteria should be based on the identified goal; replacement in-kind, out-of-kind, or
a combination; and the sustainability of the replacement site.
4 This should occur only as a result ofunforseen environmental catastrophies; compensatory
mitigation plan specifics which, due to variability of environmental factors, will not achieve
the goal; site design or construction mistakes.
5 Regulatory agencies should compile an annual report that provides a yearly update of all
compensatory mitigation efforts which are 'active' (i.e., construction or monitoring
underway). In addition, the availability of the report should be well advertised.
Figure 1. Conceptualization of the compensatory mitigation process.
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PARTI
THE MITIGATION CONCEPT
The Council of Environmental Quality (CEQ) first
denned the concept of mitigation in 1978. The
council's definition includes the following comments:
(a) Avoiding the impact altogether by not taking
a certain action or parts of an action.
(b) Minimizing impacts by limiting the degree or
magnitude of the action to its implementation.
(c) Rectifying the impact by repairing, rehabilitat-
ing, or restoring the affected environment
(d) Reducing or eliminating the impacts over time
by preservation and maintenance
operations during the life of the action.
compensatory mitigation projects incorporate
public or private arrangements for long-term
management ^_
• Compensation projects will generally be
designed and evaluated cooperatively among
project sponsors, the signatories, and appropri-
ate public and private entities.
• Monitoring and evaluation of the success of
compensatory mitigation replacement projects
shall be incorporated by the signatories as a
fundamental part of the mitigation process.
To address the above mitigation policies, the Wet-
lands Workgroup Implementation Plan included the
following actions:
(e) Compensating for the impact by
replacing or providing substitute
resources or environments.1
The Chesapeake Bay Wetlands Policy
subscribes to the CEQ definition of mitiga-
tion and defines it as a sequential process.
The "Section 404 Mitigation Memorandum
of Agreement'' (U.S. Army Corps of Engi-
neers and Environmental Protection Agency
1989) also supports the sequential mitigation
process. Furthermore, the Wetlands Policy
sets forth the following principles which
provide guidance in the development and
implementation of mitigation activities to
achieve the stated goals:
• Mitigation will be included for any
project conducted by or subject to
review or approval by the signatories
(i.e., the Chesapeake Bay Executive
Council [see glossary]).
• Compensatory mitigation shall proceed
from the presumption that "in-kind'1
and "on-site" is the preferred solution.
Other solutions, including "off-site"
and "out-of-kind" mitigation, will only
be allowed when acceptable to public/
government agencies or performed in
the context of watershed management
planning or other specific objectives.
• The signatories shall require that
Landscape Ecology
Until recently, the ecology of a wetland was studied largely by
examining the wetland itself, exclusive of the characteristics of
the landscape surrounding the study area. With the realization
that wetlands are integrally connected to this landscape, how-
ever, scientists have strived to incorporate distinctive features
of both the terrestrial and aquatic landscape into their studies.
Landscape ecology uses a holistic approach that promotes a
more comprehensive examination of wetlands and other eco-
systems by focusing on the primary ecological interactions of
the surrounding landscape (or watershed). The key to land-
scape ecology is the recognition that processes operate at a
variety of scales within a landscape. Rather than concentrating
only on the smallest-scale processes within a given wetland
parcel, it is more important to exa mine the full suite of processes
and their functions. Several factors contribute to the function of
wetlands within the landscape context: scale, thresholds, and
the size, slope, and position of the wetlands within the land-
scape (Preston and Bedford, 1988)
On a more practical level, landscapes or watersheds often cross
jurisdictional boundaries, making management at these scales
challenging. Within the landscape, wetlands and other ecosys-
tems are often ephemeral and dynamic—that is, boundaries of
a wetland may naturally shift seasonally and over longer time
periods, complicating management efforts. However, land-
scape level information can be used to minimize duplication
and enhance management efforts because it addresses the
linkages between wetland and other systems. Therefore, land
management decisions incorporate the connectivity between
units of the landscape. In addition, because landscape-level
information is comprehensive in nature and useful to a variety
of land managers, its application promotes dialogue and coop-
eration between different government units so that integrated
land management decisions result
1 Quoted material is indented and in bold type throughout the document.
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The Federal Signatory, in consultation with
appropriate governmental agencies, will
develop updated standards and criteria in
compliance with the overall wetland protec-
tion goals and specific mitigation policies
incorporating state-of-the-art technological,
ecological, and biological applications.
Traditionally, mitigation has occurred primarily at
the site-specific scale such as the filling of a wet-
land parcel for a parking lot The filling is the
direct impact and is typically addressed within
federal and state regulatory programs. Indirect
impacts, such as declining water quality due to
pollutant discharges from the parking lot, may also
be addressed. The application of the process of
mitigation in an ecological context, however,
requires an additional scale of evaluation: the
"landscape." A landscape is a spatial mosaic of
ecosystems which interact functionally (Fonnan
and Godson 1986; Gosselink et al. 1990). Ex-
amples include watersheds/ physiographic prov-
inces, and ecoregions.
In the parking lot example, the effects from the
parking lot runoff may not be limited to the
surrounding wetland community but may extend
adjacent wetlands and waterways. Within a
ib-basin, other parking lots may be contributing
similar runoff pollutants. Individually small or
insignificant activities may cumulatively affect
wetland ecosystem properties within the sub-basin
landscape negatively.
Because existing regulatory programs generally
focus on individual projects and analyses of
potential environmental impacts are usually
limited to the immediate project wetland parcel or
community, these other effects may not be evalu-
ated. Furthermore, different analyses may not be
coordinated among agencies or between regula-
tory and non-regulatory programs.
Regulatory programs are often incapable of
effectively managing impacts which originate
beyond the wetland system. The adverse effects of
numerous individual projects accumulate in time
and/or space and are called "cumulative impacts"
(Bedford and Preston 1988). Because cumulative
impacts are landscape-level phenomena resulting
from numerous regulatory and non-regulatory
decisions (Gosselink and Lee 1989), applying
mitigation only at the site-specific level will
tinue to compromise the ecological integrity of
etland ecosystems.
Cumulative Effects vs Cumulative Impacts
Although "cumulative effects" and "cumulative impacts" may
appear to be interchangeable terms at first glance, an important
distinction differentiates the two. The term, "cumulative ef-
fects," is broader scope and identifies those changes that result
from a specific alteration(s) within the wetland system. These
effects indicate only a change from the norm; no value is placed
on these changes. When society determines that certain effects
are negative, the effects then become known as impacts. In
other words, "cumulative impacts" incorporate a value judg-
ment on the ultimate effect of the changes.
Several mechanisms (Beanlands et aL 1986) may
trigger cumulative impacts to wetland ecosystems:
(1) Disturbances clustered so closely in time that
an ecosystem does not have sufficient
recovery time between the actions and
resulting effects. Disturbances of this nature
are "time-crowded perturbations."
(2) Disturbances occurring dose together or
overlapping so that the effects are concen-
trated in a specific area. Such disturbances
are "space-crowded perturbations."
(3) Individual disturbances which collectively
produce effects that are quantitatively and
qualitatively unlike the individual perturba-
tions. These disturbances are called "syner-
gistic" effects.
(4) Disturbances which cause successive actions
producing effects that are temporally or
spatially distinct from the original distur-
bance. Disturbances of this form are defined
as "indirect" effects.
(5) Disturbances which result in small changes
(i.e., incremental effects) or produce a
gradual diminution in quality or quantity
(i.e., detrimental effects).
Wetland ecosystems are closely coupled with
terrestrial and aquatic systems (Nixon and Oviatt
1973; Likens and Bormann 1974; Mulholland and
Kuenzler 1979; Brinson et al. 1981; Odum et al.
1984). Transport mechanisms, such as water,
animals, wind, and people control the flow of
materials and energy across the ecosystem bound-
aries within a landscape (Fonnan and Godson
1986). While much remains unknown about these
linkages, integrating information derived from
landscape-level analyses into regulatory programs
is critical if the mitigation sequence is to have
ecological meaning.
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10
This document addresses the ecological context of
mitigation, particularly as it applies to compensa-
tory mitigation site-selection criteria. Understand-
ing each component of the sequential process is a
prerequisite to the ecological application of the
mitigation concept.
Avoidance
Avoiding an impact to a wetland parcel, commu-
nity, and system is the first step in the sequential
process of mitigation. Analyzing the potential
impacts from a proposed project requires site-
specific and landscape level evaluation. The
nature of cumulative impacts in relation to the loss
of wetland ecosystem function suggests that even
small wetland communities or parcels may be
important within a landscape context (Odum 1978)
and the application of the sequential process to
proposed projects in such areas is ecologically
sound.
With respect to current federal regulatory prac-
tices, the application of avoidance pursuant to
Section 404 must adhere to the 404(b)(l) guidelines
which largely parallel the NEPA guidelines. The
principles upon which the guidelines are based,
however, can be applied in a broader context.
These guidelines are the environmental standard
against which projects are measured to secure a
Section 404 permit To satisfy the avoidance
directive in the guidelines, an applicant's proposal
must meet all of the following standards:
1. No practicable alternatives to the proposed
discharge exist (Section 230.10(a»;
2. The proposed activity complies with other
environmental standards (i.e., state water
quality standards; toxic effluent standards or
prohibitions pursuant to Section 307; Endan-
gered Species Act; and the Marine Protec-
tion, Research, and Sanctuaries Act of 1972)
(Section 230.10(b)); and
3. The project will not cause significant degra-
dation and adverse effects (Section
230.10(c)).
Due to their rarity or unique faunal or floral
assemblages, some types of wetland communities
are ecologically difficult to replicate and may be
immitigable, regardless of the type of compensatory
mitigation proposed. Examples include wetlands
characterized by the U.S. Fish and Wildlife Service
(1981) as "Resource Category 1" or wetlands identi-
fied by state Natural Heritage Programs such as
Atlantic white cedar communities or the Delmarva
Bays.2 Many of these rare or unique communities are
hydrologically linked to other wetlands. Impacts to
the linked wetlands may result in ecological damage
to the rare or unique communities. It is, therefore,
important to evaluate not only alternatives to direct
impacts but also those to .indirect impacts.
Within the federal and state regulatory programs,
the most effective way to avoid impacts to wetland
systems is to address the issues at the local level
Enhanced communication concerning federal and
state program processes and requirements is criti-
cally needed between local planning entities and
federal and state agencies. The programs designed
to avoid wetland impacts must incorporate im-
proved gathering and dissemination of natural
resource information. Additionally, improved lines
of communication among government agencies, the
regulated community, and the general public must
exist along with better integration of resource
information into local planning activities at a scale
that is sensitive to wetland ecosystem properties.
These improvements will enhance effective decision
making; subsequently, wetland resources will be
more effectively regulated.
Section 230.80 of the 404(b)(l) Guidelines is one
mechanism for addressing avoidance within a
landscape context. This section of the guidelines
discusses the application of "Advanced Identifica-
tion" (ADID) of disposal sites in general terms. In
the ADID process, the COE and EPA identify
wetlands or other waters of the U.S. as:
(1) Possible future disposal sites, including
existing disposal sites and non-sensitive
areas; or
(2) Areas generally unsuitable for disposal site
specifications.
The identification of sites as "possible" or "generally
unsuitable" does not constitute a permit decision nor
does it prohibit anyone from applying for a permit in
any of the identified sites. Ecological information
concerning wetlands and other systems is provided
1 The U.S. Fish and Wildlife Seivice lists four 'Resource Categories' in Hs Mitigation Policy. Resource Category 1 is tiabitat to be
impacted is of high value for evaluation species and is unique and irreplaceable on a national basis or in the ecoregion section.' The
'Mitigation goal' for Resource Category 1 habitat is 'no loss of existing habitat value.'
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11
through the ADID process in a manner which is
it often available to .the regulatory agencies
ig routine permit evaluations and which
ilitates permit processing. While the process is
focused on the federal regulatory program, ADID
may provide helpful information to assist local
planning and permitting agencies, land trusts,
conservation organizations, and other entities
whose decisions may affect wetland systems
within the ADID landscape. Moreover, landscape
analyses can be conducted either apart from or as a
precursor to a formal ADID.
Minimization
Once all efforts to avoid impacts have been ex-
hausted, minimizing adverse impacts to a wetland
parcel, community, or system is the second step in
the mitigation process. For projects requiring a
Section 404 permit, a thorough analysis of efforts to
minimize project impacts to a wetland parcel or
community is mandatory (see Section 230.10(d) of
the guidelines). Subsection H of the guidelines
provides a listing of actions which should be
investigated to minimize detrimental effects to
wetland systems (see Section 230.70 through
1230.77 of the guidelines). This list can also
jvide guidance for minimization efforts relative
fb activities that do not require a Section 404
permit.
The following example illustrates efforts to mini-
mize impacts to a wetland parcel.
A marina is proposed in "waters of the United
States" and all efforts to avoid wetland impacts
have been undertaken. Placement of piers across a
freshwater marsh is "unavoidable," however,
several options are available: (1) reducing the size
and/or number of piers proposed; and/or (2)
relocating all or some of the piers to cross the
narrowest portion of the wetland. Either option, or
both, will minimize adverse potential impacts to
the marsh. Like avoidance, investigating all efforts
to minimize adverse impacts to wetland systems is
a necessary step of the mitigation process. The same
principles apply in cases of bulkhead construction,
direct filling, or other regulated activities which may
result in adverse effects to the wetland parcel.
Compensatory Mitigation
The final step in the sequential mitigation process is
compensating for alterations to wetland systems known
as compensatory mitigation.3 To initiate the application
of wetland functional replacement in compensatory
mitigation projects (Le., replacing the functions of the
altered wetland community at the compensatory
mitigation site), site-selection criteria must involve
variables such as "in-kind," "out-of-kind," "on-site,"
"off-site," and "hydrologic, structural, and functional
equivalency" to evaluate compensatory plans.
In the Chesapeake Bay Wetlands Policy,"... compensa-
tory mitigation... must not substitute for efforts to
avoid or minimize losses or prejudice an agency
determination affecting wetlands" (Chesapeake Bay
Executive Council 1988). Compensatory mitigation
generally involves restoration, creation, and enhance-
ment which Part n covers in detail.
Recently, the VS. Environmental Protection Agency
published the two-volume report entitled Wetknd
Creation and Restoration: The Status of the Science (Kusler
and Kentula 1989a and 1989b). This report identified
three general conclusions on the scientific aspect of
wetland restoration and creation:
1. Practical experience and available scientific
data bases on restoration and creation are
limited for most wetland types and vary
regionally.
2. Most wetland restoration and creation
projects do not have specified goals, compli-
cating efforts to evaluate "success."
3. Monitoring of wetland restoration and
creation projects has been uncommon.
The third conclusion is of concern to those reviewing,
permitting, designing, and implementing compensa-
tory mitigation projects since it indicates that there is
minimal information on the "functional" replacement
of wetlands. Attempts to replace natural wetland
functions are currently based on incomplete data since
effective methods to quantify or assess wetland func-
tions are still evolving. Similar to other wetlands in the
United States, the scientific data base is incomplete for
Chesapeake Bay wetlands, particularly its nontidal
wetland ecosystems. Yet, despite this deficit, alterations
to these systems continue.
compensatory mitigation* is used throughout this document in lieu of the shorthand term 'mitigation.' Mitigation, as defined
this document and following existing federal laws, regulations, policies and agreements, is the sequential process of avoidance,
fimization, and compensatory mitigation. Compensatory mitigation, therefore, is only one component of the whole mitigation
process. The two terms are not interchangeable nor equivalent in meaning.
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12
PART II
COMPENSATORY MITIGATION SITE
SELECTION CRITERIA:
ECOLOGICAL CONSIDERATIONS
Introduction
Historically, compensatory mitigation has been
viewed from two perspectives;
1) As a means to an end (Le., receiving a permit
to conduct work in wetland systems).
2) Creating (usually) or restoring a site to
satisfy the permit condition with little, if any,
evaluation of the ecosystem processes and
functions of the project wetland.
More recently, the emphasis has been on not only
replacing lost wetland acreage but also wetland
function. (Quammen 1986; Kusler and Kentula
1989a). Partly due to wetland ecosystem variabil-
ity, £xa£t replication of a wetland community (e.g.,
structure, processes, functions), is unlikely. This
document suggests that development and subse-
Pulsed Stability in Wetlands
Wetlands, more than many other systems, are subject to
constantly changing physical and chemical conditions. Often
these changes are acute and rapid so that a wetland exists more
in a state of dynamic equilibrium rather than following a linear
path towards some marked successional endpoint These
changes, known as pulses, can cause wetlands to remain in an
ever-changing state of development
A variety of physical forces impose pulses upon the wetlands.
Some of the more frequent include tides which cause both
nutrient fluxes and the periodic aeration and Hooding of the
substrate, patterns of drought and fire which cause changes in
decomposition rates and modifications in the hydrologic con-
dition of the soil, and drought and flooding which can signifi-
cantly affect seed germination and vegetation survival particu-
larly in freshwater wetland systems.
At one time, pulses of most sorts were regarded as destructive.
Wetland ecosystems, however, are adapted to these sorts of
fluctuations and the pulses are critical to their survival. In
maintaining existing wetlands, projects impacting these sys-
tems must account for the inherent variability and minimize
disruption of natural pulses. In creating new wetlands, a
balance must be found that mimics the natural variability of a
particular type of wetland without creating pulses that swing so
wildly or are so frequent that the system does not have
adequate response time.
quent implementation of compensatory mitigation
plans may use the functions; values, and structure
of the project wetland community as a model.
Some argue that human impacts to landscapes are
so pervasive that replacement of wetland charac-
teristics modeled on these communities is not
ecologically sound since they are "degraded."
Although this is true in some situations, making a
decision that a wetland parcel or community is
completely "degraded" based solely on the appear-
ance of the site may be more questionable.
The approach presented in this document is
founded on the following principles and concepts:
• A key principle of wetland ecosystems is that
they are dynamic (Willard and Miller 1989).
These ecosystems vary bom temporally and
spatially and are "pulsed" (Niering 1987). The
variability so characteristic of wetland systems
largely results from the hydrology and its
effects on the internal properties of a wetland
community (e.g., vegetation community
structure or composition, microtopographic
relief, primary productivity, organic matter
decomposition, and faunal assemblages).
Whether a wetland community is dominated
by surface water or groundwater regimes (or a
combination of the two), hydrologic processes
exhibit temporal fluctuations. These fluctua-
tions occur daily, seasonally, and annually.
This temporal hydrologic variability is a
"natural disturbance" (White 1979). Other
relevant natural disturbances include fire,
wind or ice storms, shoreline ice buildup and
movement, temperature fluctuations, coastal
and alluvial soil deposition and erosion,
coastal dune movement, salinity fluctuations,
and intrusion of salt water into freshwater
wetlands (modified from White 1979). An
evaluation at a site is a snapshot of the dy-
namics which structure the wetland commu-
nity at that particular moment. Components
of compensatory mitigation plans—site
selection, monitoring, and design criteria—
need to reflect this inherent variability.
• Wetland systems can. be characterized along a
continuum of anthropogenic disturbance,
with "pristine" wetlands at one end and very
disturbed (degraded) wetlands at the other
(Figure 2). There are many wetland ecosys-
tems, however, that are often considered
degraded when in fact they have not com-
pletely deteriorated. These wetland systems
continue to provide values to society even
though they have been altered physically in
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23
PRISTINE
DISTURBED
DEGRADED
I
Relatively
Undisturbed
Moderately
Disturbed
Highly
Disturbed
Figure 2. The wetland disturbance continuum
some manner and are "disturbed." systems.
Disturbed wetlands have adjusted to the
fluctuations caused by human activities that
have altered the surrounding landscape.
Unless a site is fundamentally degraded
(based on valid scientific evidence), it is
generally more appropriate to use the existing
wetland communities as templates for com-
pensatory mitigation.
Within the continuum, smaller scale
continuums characterize each disturbance
type. For example, wetland systems classified
as disturbed may be highly disturbed, moder-
ately disturbed, or relatively undisturbed.
The purpose of recognizing a disturbance
continuum is to identify the effort required for
compensatory mitigation efforts.
• Management actions for specific landscapes
may not use the existing wetland community
model for compensatory mitigation due to
existing landscape conditions. Two common
examples include: (1) highly urbanized areas
in which the wetlands may not yet be de-
graded but are reduced in number or acreage
or lack the appearance of functional integrity;
or (2) degraded wetlands. Both situations offer
several options:
Highly urbanized settings: Detailed
hydrogeochemical and biotic analyses are
often necessary to determine the functional
status of the wetland systems in the land-
scape. Consideration of aesthetics should be
distinct from ecological function. The analy-
ses should then be used to develop a land-
scape management plan for compensatory
mitigation. Effective functional replacement
in urbanized settings, however, may require
additional wetland ecosystem acreage beyond
that typically mandated in compensatory
mitigation plans.
Degraded
communities or sstms:
Degraded wetland systems are those altered
by toxic substances or other pollutants mat
result in unpaired ecosystem processes and
functions, and lack any societal benefits (e.g.,
water quality deterioration from heavy metal
loadings resulting in the closure of shellfish
bed harvesting or the restriction of recre-
ational fishing). Degradation usually results
from watershed land practices. Using de-
graded systems as models for the replacement
of wetland losses is not generally desirable.
The identification of such areas is important,
however, to implement remedial actions
within the landscape and reverse degradation
of the wetland system. The use of compensa-
tory mitigation as a sole remedy will probably
not result in ecologically meaningful long-
term replacement if the sources of the degra-
dation remain untreated or if other communi-
ties in the vicinity of the wetland system are
not rehabilitated.
1 Landscape-level analysis may indicate
changes in wetland ecosystem functions due
to recent land use practices. These practices
are accompanied by a decrease in the
wetland's ability to perform certain functions
and benefits. These changes may dictate
several responses regarding compensatory
mitigation:
A determination is made that compensatory
mitigation efforts will not use existing wet-
land communities as models. This decision
may require the use of intensively managed
systems such as stormwater ponds.
A verification of wetland functional change
and the associated decrease in ecosystem
values may prompt changes in the land
practices causing the adverse effects. The
response of the wetland to changes in land
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14
practices should be monitored to determine
whether compensatory mitigation efforts
should continue to use models of existing
wetland communities. A decision to either
alter the mitigation model or abandon it
altogether (and develop a new model based
on the monitoring results) will then be based
upon the best available information.
• • The federal permit program generally
' requires compensatory mitigation for
moderate or large-scale projects in which
significant impacts to wetland systems are
easily identifiable. A comparable require-
ment is not generally applied to projects in
which the impacts are small either in terms
of acreage or measurable functional loss. The
guidance in this document does not distin-
guish between the requirements for compen-
satory mitigation based on size or the degree
of project impact In circumstances where
wetland losses result from unregulated
activities, guidance in this document can be
used to direct efforts in which restoration,
creation, or enhancement is deemed appro-
priate or necessary.
• Regardless of the type of compensatory
mitigation or whether the existing wetland
community serves as the mitigation tem-
plate, compensatory mitigation will not
maximize ecological function unless it is
integrated into a landscape perspective.
Many of the information sources and
methods for landscape analysis are presently
beyond the scope of regulatory programs at
any level. Current efforts in the Chesapeake
Bay basin, however, are developing land-
scape-level information which will enhance
compensatory mitigation efforts. It is also
incumbent upon federal, state, and local
agencies involved in regulating wetland
systems to develop a mechanism for gather-
ing, sharing, and implementing landscape-
level information.
The previous discussion outlines many of the issues
addressed in mis section of the document and lays
the foundation for the more detailed discussions
which follow.
The compensatory mitigation process involves
several steps (Figure 1). The following informa-
tion, however, is limited to steps 1 through 3.
Information relevant to steps 4,5,6 and 7 will be
developed in the future for inclusion as additional
chapters.
Wetland Compensatory Mitigation
Site Selection'Criteria
Site selection criteria are those variables funda-
mental to the development of a viable compensa-
tory mitigation effort. They are particularly
important in plan development and serve as the
ecological goals of each compensatory mitigation
effort. A complete evaluation of the variables is
critical for both the affected wetland community
and the replacement site(s). Information on the
variables should be collected at both the commu-
nity and landscape levels. The variables presented
below constitute the site selection criteria needed
for the effective review of wetland compensatory
mitigation plans:
Variable 1: Identification of wetland hydro-
logic core and structural factors
Variable 2: Identification of wetland ecosystem
processes, functions, and values
Variable 3: Identification of compensatory
mitigation types
Variable 4: Identification of in-kind or out-of-
kind replacement
Variable 5: Identification ofon-site or off-site
location
Variable 6: Identification of compensatory
mitigation timing
Variable 7: Identification of lands compatible
with compensatory mitigation efforts
Variable 8: Identification of lands not com-
patible withxompensatory mitigation
efforts
Variables 1 through 3 for the project wetland are
the baseline data. Baseline data serve as funda-
mental sources of information critical for the
replacement of wetland ecosystem properties.
These data may be collected by the project sponsor
or a consultant for the project sponsor, federal, or
state agency employees. Application of variables 4
through 8 should be determined by federal and
state regulatory and review agencies.
Variable 1: Identification of wetland ecosystem
hydrologic core and structural factors
1A. HYDROLOGIC CORE FACTORS
Hydrology is the driving force shaping wet-
lands (Gosselink and Turner 1978) and describes
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15
the water movement into, through, and out of a
wetland ecosystem. The balance between the
|inflows and outflows is the water budget
(Mitsch and Gosselink 1986). The inflow
components of the water budget are precipita-
tion, surface runoff, groundwater discharge,
and, where appropriate, tidal inflow. Evapo-
transpiration, surface outflow, groundwater
recharge, and tidal outflow constitute the
outflows of water from wetland ecosystems
(Mitsch and Gosselink 1986; Zimmerman 1988).
Determining a water budget as part of compen-
satory mitigation is expensive since several of
the parameters are difficult to measure precisely
(e.g., evapotranspiration rates). In lieu of
developing a water budget for each project, it
may be more practical to focus on elements of
the water budget components.
The physical replacement of a wetland and its
attendant ecosystem processes and functions
(and the goods and services provided by them)
are dependent upon several hydrological
properties termed "core factors" (Brinson and
Lee 1989). Core factors largely determine the
wetland community which will result from
compensatory mitigation efforts since they
define the "energy signature" of a particular
etland community or ecosystem (Odum 1983).
.e core factors consist of the hydroperiod,
hydrologic energy, and nutrient regime. If a
compensatory mitigation plan does not include
information on these factors, one cannot deter-
mine what type of wetland community will
result from the compensatory mitigation effort.
Predictions concerning the wetland functions
and values likely to result as well as the physical
and ecological resemblance to the affected
wetland will be uncertain.
1A1. Hydroperiod
Hydroperiod is defined as the depth, duration,
frequency, and timing of both inundation or of
the seasonal highs of water table (in part, after
Brinson et al. 1981; Hollands et al. 1986), or the
"seasonal pattern" of water level for a particular
wetland community (Mitsch and Gosselink
1986). Depth is defined as the water level
during flooding, ponding, or soil saturation (as
measured in an unlined borehole). Duration
describes the length of time of a specific hydro-
logical event (typically measured in days or
months). Frequency describes the return
interval of a particular hydrologic event. Tim-
ing describes when a particular hydrologic
•ent occurs (e.g., during the winter/spring,
January through June).
1A2. Hydrologic Energy
The hydrologic energy of wetland ecosystems
describes the direction and source of water
(Brinson and Lee 1989; Brinson 1988; Gosselink
and Turner 1978). Hydrologic energy direction
is vertical, bidirectional, or unidirectional
(Brinson 1988). Wetland communities in
topographic depressions (e.g., Delmarva Bays)
typically exhibit vertical hydrologic energy due
to fluctuations in groundwater levels. Bidirec-
tional flow is characteristic of tidal and lakeside
wetlands, resulting from lunar or wind influ-
ences on surface waters. Wetlands along
drainage pathways may be influenced by
unidirectional hydrologic energy as a result of
overbank flow (Brinson and Lee 1989).
The force of a particular type of hydrologic
energy on a wetland system can be described
along a continuum (Brinson and Lee 1989), with
depressional wetland systems exhibiting low
hydrologic energy, tidal/lakeside wetland
systems having intermediate energy, and
streamside wetland system communities
showing high hydrologic energy. Each energy
signature has specific variables which control
the effect of the hydrologic energy direction.
For example, overbank flows have unidirec-
tional hydrologic energy which may vary both
in velocity and the aerial extent of flooding
through a wetland system for a particular storm.
Seasonal and daily fluctuations in vertical
hydrologic energy may exist laterally within
some wetland systems which exhibit both
groundwater discharge and recharge capabili-
ties (Doss 1991). Tidal amplitude varies daily,
seasonally, and annually when bidirectional
hydrologic energy dominates. Understanding
the mechanics and dynamics of the hydrologic
energy direction in a wetland system aid in
defining its ecosystem processes, functions, and
values.
Many wetland systems throughout the Chesa-
peake Bay basin exhibit more than one pattern
of hydrologic energy. For example, wetlands on
floodplains of the Coastal Plain physiographic
province of Maryland and Virginia experience
some degree of overbank flooding. Although,
the duration of flooding is relatively short,
water table levels remain high following the
flood event. If such an event occurs during the
peak of vegetation growth (July-September),
then evapotranspiration will readily lower the
high water table. During this same period,
however, precipitation levels tend to be high
and a cycle of overbank discharge coupled with
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16
a seasonally high water table may be common.
Groundwater fluctuations appear to dominate
most of these floodplain wetland systems, but
•surface flooding also affects nutrient cycling,
vegetation community dynamics,
microtopographic relief, organic matter produc-
tion, decomposition, organic and dissolved
carbon export, and biotic interactions.
Identification of water sources to the project
wetland and the compensatory mitigation site(s)
is critical since the water chemistry of these
sources may vary considerably and affect the
wetland ecosystem processes and functions.
Possible sources include overland runoff, direct
precipitation, groundwater, overbank flooding,
tidal exchange, or a combination of these
sources. It is advisable to use long-term hydro-
logic data when available (e.g., U.S. Geological
Survey river gaging stations, U;S. Soil Conserva-
tion Service water table wells, U.S. Army Corps
of Engineers navigation or flood control
projects), since a single observation (e.g., day,
season, or year) of hydrology does not charac-
terize the long-term hydrologic dynamics
affecting wetlands. Indeed, as Loucks (1989)
notes,"... the size and return period of ex-
treme events must be considered ... the signifi-
cance of return-time consideration lies in the fact
that restoration on a large number of wetlands
must be designed for events that are unusual
locally, but fairly frequent over a large popula-
tion of wetlands."
Where waterways (e.g., small tributaries and
tidal guts) are part of the project wetland and/
or replacement effort, it is necessary to investi- .
gate the morphology of either the existing
waterway or one which serves as a model for
the replacement site.
1A3. Nutrient Supply
The nutrient supply is a function of the
hydroperiod, particularly duration, as well as
"residence time" which is the average time that
water remains in a wetland community or
system (Mitsch and Gosselink 1986). It is
important to identify nutrient sources, constitu-
ents, and fluctuations along with hydrologic
energy characteristics of the project wetland and
compensatory mitigation site. Sources of
nutrients include adjacent, upstream, and
downstream land uses and vegetation cover
types; soils; precipitation; wind; and biotic
contributions (e.g., presence of a seasonal
waterfowl or wading bird population, wastewa-
ter treatment plant effluent). Plans for temporal
changes in nutrient supply at the compensatory
mitigation site and integrating some require-
ments for remedial actions in the monitoring
component of the plan are important if these
fluctuations are necessary to achieve the goals of
the replacement effort.
Craft et al. (1988) found that three regularly
flooded marshes with organic substrates had
higher concentrations of nitrogen (N), carbon
(C), and phosphorus (P) than three comparable
marshes that were created. Two natural marshes
with mineral soils, however, had similar N, C,
and P concentrations compared to two created
marshes. Researchers attribute this similarity to
the relatively young age of the natural marshes
and the hydrologic regime of the compared
sites. In addition, total C and N pools of the
natural marshes were significantly larger than
those for the created marshes. As a result of
tidal exchange, salt and brackish water marshes
may have adequate supplies of Mg, Ca, K, and
S, and fertilizer or other soil amendments may
not be required for these elements. However, N
and P may be limiting, particularly in sandy
substrates or where the topsoil at the replace-
ment has been stripped (Broome 1989). Nutrient
conditions and dynamics, therefore, need to be
identified prior to wetland replacement (Broome I
1989).
IB. STRUCTURAL FACTORS
Closely linked to the hydrologic core factors are
the other physical features which influence
wetland ecosystem processes, functions, and
values. The structural factors consist of geo-
morphic features and geologic substrates,
vegetation, and landscape setting.
1B1. Geomorphic Features and Geologic
Substrates
Wetland communities and systems exhibit a
variety of geomorphic features that are under-
laid by differing geologic substrates which
should be documented at both the project
wetland and substrate sites. Many of these
elements are closely linked with the hydrologic
dynamics.
IBl(a). Physiographic provinces. The character-
istics of each physiographic region affect the
distribution, biotic assemblages, and values of
wetland communities and systems (Heeley and
Motts 1973).
lBl(b). Geomorphic setting. This factor refers to
the landforms on which wetland communities
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27
are situated. For example, to determine the
) cumulative effects of wetland alteration on
water quality, Brinson (1988) proposed classify-
ing wetlands into three categories: basin
(depressional wetlands); riverine (riparian
wetlands); and fringe (tidal wetlands). This
classification is tied closely to the hydrologic
energy directions discussed above. Together,
the two factors characterize the
hydrogeomorphic setting of the project wetland
communities, clarifying desired replacement site
characteristics. Each of the geomorphic loca-
tions also provides a genera] description of
hydroperiod and nutrient supply (Brinson 1988).
This hydrogeomaphic classification has since
been revised, and in addition to the previous
three wetland categories includes extensive
peatlands (i.e., blanket bogs) (Brinson 1993).
The hydrogeomorphic classification serves as
the foundation for the functional assessment
models under development by the Corps of
Engineers, Waterways Experiment Station (Dan
Smith, personal communication). It will also
provide a useful tool to implement compensa-
tory mitigation within a landscape context (e.g.,
throughout a watershed).
Another means of describing the geomorphic
ig of wetland systems is through a
hydrogeologic characterization of the landscape
(O'Brien and Motts 1980). This classification is
landscape-based and uses a variety of data
sources to establish the hydrogeomorphic units,
including surface and groundwater characteris-
tics, land use and vegetation cover type, surfical
geology, topography, physiography, and soil
properties (O'Brien and Motts 1980). This type
of classification enhances the understanding of
the relationships among hydrology, geomorphic
setting, and wetland ecosystem properties.
Recently, the U.S. Geological Survey identified
and classified the two regional geomorphic
settings of the Delmarva Peninsula into
"hydrogeomorphic units" (Phillips 1992;
Phillips et al. 1993). Results of the hydrologic
and nutrient analyses conducted on the
Delmarva Peninsula indicate that wetlands
located in different hydrogeologic units (i.e.,
different hydrogeologic settings) alter ground-
water quality differently (Phillips et al. 1993).
IBl(c). Macrotopography. Topography may be
viewed at either broad or detailed scales; both
are relevant to wetland compensatory mitiga-
ion efforts. Macrotopography refers to the
ilope and elevation of the project wetland—
important variables to establish for use in the
replacement site. Both are closely linked to
hydroperiod and hydrologic energy direction
and source.
Slope and elevation, as well as tidal amplitude,
are important in the replacement of salt and
brackish water marshes (Broome 1989). These
three elements determine the boundary between
the "low" and "high" marshes (Broome 1989).
Broome recommends observing or measuring
the lower and upper elevation limits of a
neighboring marsh. McKee and Patrick (1988)
reviewed the existing literature to determine the
relationship between Spartina alterniflora and
tidal elevations along the Atlantic and Gulf
coasts. This analysis revealed a positive correla-
tion between mean tide range and the growth of
Spartina alterniflora relative to elevation. In
addition, they cite other biotic and abiotic
factors which may, in addition to tidal ampli-
tude, limit the distribution of Spartina alterniflora
along the elevational gradient. These factors
including edaphic features (e.g., salinity, avail-
able nutrients, and redox potential), interspecific
competition, and natural and human distur-
bance (e.g., mosquito ditching). In addition,
elevation may be a significant factor controlling
particle size as well as the amount and disper-
sion of nutrients within marsh communities
(Lindau and Hossner 1981).
The slope of a project wetland should serve as a
guide for the replacement site gradient. Slopes
of tidal wetland communities are another
important element in determining the aerial
extent of marsh vegetation. The steepness of a
slope will affect the dissipation of wave energy
which in turn influences plant colonization and
survival (Woodhouse 1979; Broome 1989).
Gentle slopes dissipate wave energy over a
broad area, whereas steep slopes concentrate the
force of the wave over a small distance. Slopes
which are too flat, however, may impede
drainage, limit soil aeration, and concentrate
salts which may inhibit the growth of desired
plant species.
Elevation and slope are also important in the
replacement of nontidal wetland communities.
Slopes which are too steep will not exhibit the
desired hydrologic conditions and be subject to
significant erosion. Because of the linkages with
hydroperiod and elevation, incorrect elevations
may result in significantly longer or shorter
hydroperiods than those of the project wetland.
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18
IBl(d). Micro-relief. Micro-relief (microsite)
refers to the fine-scale topographic heterogene-
ity exhibited by most wetland communities as a
function of substrate, hydrologic dynamics and
other physical disturbances, and biotic forces.
Excluding some tidal shoreline wetland com-
munities, the "hummocky-hollow" nature of
wetland communities is fairly common, par-
ticularly in those areas with organic substrates
and long periods of soil saturation. Micro-relief
is also present in many forested floodplain
wetland communities where floods have
moved sediment and other debris so that a
variety of microtopographies exist across the
site. Downed and decaying woody materials,
such as tree stumps, trunks, limbs, exposed
roots, or mounds from tree uprootings also
cause small-scale differences in relief. Micro-
relief is important in the regeneration of
wetland vegetation communities (Huenneke
and Sharitz 1986). The distribution and diver-
sity of microsites may differ significantly
between wetland communities and even within
a community due to disturbance (Huenneke
and Sharitz 1986).
Where possible, compensatory mitigation plans
should incorporate micro-relief features of the
project wetland at the replacement site based on
an evaluation of the factors responsible for the
micro-relief at the project wetland. This evalua-
tion will determine if similar factors exist at the
replacement site, the temporal nature of these
factors, the abundance and types of microsites of
the project wetland, design specifications needed
to achieve the desired micro-relief features, and
monitoring requirements.
IBl(e). Soil properties. The important soil
properties of wetland communities include:
texture, organic matter content and structure
(applicable for peatlands), types of horizons
present and their corresponding depths, pH,
redox potential, soil salinity, nutrient pool,
cation exchange capacity, conductivity, and
Munsell color (matrix and mottles). Soil
characteristics which indicate hydrologic
dynamics such as the presence of iron and
manganese concretions and oxidized rhizo-
spheres, porosity, hydraulic conductivity, bulk
density, presence of toxic substances (heavy
metals, pesticides, herbicides), and measure-
ments for wetland gases (methane, ethylene,
hydrogen sulfide) (Veneman 1986; Pacific
Estuarine Research Laboratory 1990) are also
important.
Evaluating several of the soil properties listed
involves some data collection and laboratory
analysis. Due to differences in soil properties
between wetland communities, it is not practical
to determine what soil properties must be
measured for all sites. It is, therefore, advisable
to have a suite of soil properties evaluated for
different types of wetlands based on the estab-
lishment of "reference wetland communities"
(see pages 26 - 27 for a discussion of reference
wetlands).
1B1 (f). Surficial geologic characteristics.
Wetland ecosystem distribution and the diver-
sity of wetland communities are related to
surficial geologic characteristics which affect the
hydrologic dynamics (Heely and Motts 1973).
Phillips (1992) found groundwater movement
beneath forested wetlands along drainage
divides in the upper sandy zone of the surficial
aquifer. Groundwater pathways beneath
forested riparian wetlands occurred in the lower
sandy zones of the same surficial aquifer. The
results from this study help to elucidate the
relationship between the geomorphic position of
wetlands and their hydrogeologic dynamics,
and the way in which this relationship affects
wetland ecosystem structure, processes, func-
tions, and values.
lBl(g). Underlying bedrock. This feature may be
important in evaluating the hydrologic proper-
ties, functions, and values of wetland communi-
ties in some physiographic provinces (e.g., the
Appalachian Plateau).
1B2. Vegetation
Wetland vegetation dynamics refers to the
temporal and spatial changes exhibited by the
structure and composition of wetland ecosys-
tems as a result of changes in the environment
(Neiring 1987). One of the most important
environmental factors responsible for wetland
vegetation changes is hydrology. The relevance
of vegetation dynamics to wetland compensa-
tory mitigation efforts is the recognition that
the vegetation composition at any one time is
the result of both past and present changes in
environmental conditions. While we may use
such data as part of the replacement model,
continual structural and florisric changes are
inevitable. Understanding the elements in-
volved in wetland vegetation dynamics is key in
evaluating the vegetation at the project wetland
and transferring that information to the replace-
ment site, as well as determining monitoring
requirements.
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lB2(a). Succession. For many years, succession
was viewed as the predictable and directional
ge in vegetation community structure and
sition over time in both wetlands and
other systems. Succession was accepted as the
result of autogenic factors within the commu-
nity, always moving towards a single "climax"
community ultimately determined by the
regional climate (Clements 1916,1936). As an
alternative to this model, Henry Gleason (1939)
proposed that local environmental conditions
determine the composition of a plant unit and
time and space variability cause changes in the
environmental conditions—the "individualistic
concept" of plant succession.
Studies by Whittaker (1953 and 1967) and others
resulted in greater support of the individualistic
concept as opposed to the Qementsian "climax"
view. Their analyses demonstrated that plants
are individually distributed along "environ-
mental gradients" and that changes in plant
species composition are related to changes in
these environmental gradients (van der Valk
(1982). For wetland ecosystems, the spatial
differences within and between wetland com-
munities are affected directly or indirectly by
Allogenic vs Autogenic Factors
Studies on succession have bng been dominated by the
relative importance of allogenic vs autogenic factors in driving
changes in vegetation. Autogenic factors are those changes in
the ecosystem caused by the plants themselves. Plants alter
the environment by shading the ground, adding and removing
nutrients from the soil, minimizing temperature fluctuations,
changing the micro-climate, and altering the soil structure.
Thus, changes through time to the ecosystem as a whole result
from self-contained factors within the environment
Allogenic factors also drive successional change. Unlike the
biological autogenic factors, however, allogenic factors are
geological, physical, or chemical changes which propel suc-
cession. The local organisms have no control over this sort of
wholesale ecosystem change because the alterations are
caused by external forces.
Wetlands are driven predominantly by allogenic factors al-
though autogenic factors do alter the environment to some
degree. Of the allogenic factors, hydrology is most important
in determining allogenic succession. The ecosystem hydrol-
ogy can be described by the hydroperiod-the seasonal fluc-
tuations of a wetla nd's water level-along with the type of local
landforms, other local water bodies, water sources, precipita-
tion, and the chemical constituency of the wetland's water.
Tides also influence the hydrology of coastal and some estua-
rine wetlands.
changes along the "moisture gradient." As such,
the Clementsian model of "succession" is gener-
ally not relevant to wetland ecosystems (Van der
Valk 1981; Neiring 1987). Because hydrology
exerts such a considerable effect on wetland
vegetation dynamics and hydrologic conditions
are inherently variable, existing wetland ecosys-
tems are likely to remain until human or natural
disturbances alter the hydrologic connection (van
der Valk 1982). Wetland communities are greatly
influenced by allogenic factors although
autogenic processes (e.g., competition) are also
important (Neiring 1987).
In lieu of the Qementsian model, van der Valk
(1981) proposed a "Gleasonian" model for
succession in wetland ecosystems. The model
focuses on wetland vegetation "succession" (i.ev
annual changes in the floristic composition of
vegetation within a wetland site) in response to
three life history traits: the potential life span of
a species, propagule longevity, and propagule
establishment requirements as affected by
fluctuating water regimes (van der Valk 1982).
lB2(b). Seed Banks. Because of the limited
information available on life history characteris-
tics of wetland vegetation, the Gleasonian model
of succession is qualitative and depicts
allogenic succession only. One important
contribution of this model, however, is that
it highlights the relevance of wetland
vegetation seed banks for compensatory
mitigation efforts. A seed bank is "... the
number, store, or density of viable seeds in
the soil at a given time" (van der Valk et al.
1992). In addition to seeds, other vegetative
propagules are included in the seed bank
Van der Valk and Davis (1978) examined
the relationship of seed banks to vegetation
dynamics in glacial prairie marshes of
Iowa. They identified three categories of
seed banks present in this type of wetland
system and determined that changes in
water level and the muskrat population
were primarily responsible for the cyclic
vegetation changes occurring at intervals
between five and 30 years. Leek and
Graveline (1979) investigated the seed bank
of freshwater tidal marshes in New Jersey
and found a diverse seed bank which
reflected the standing vegetation. Van der
Valk and Davis 1978 reported similar
results for the prairie glacial marshes
although Milton (1939) did not find similar
findings for a salt marsh.
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20
The Seed Bank
In wetlands, the seed bank is the substrate that contains the
seed reserves for the immediate wetland plant community.
Seeds transported to the seed bank either by wind or water
dispersal often remain dormant until conditions suitable for
their germination occur. The seed bank also contains vegeta-
tive propagules in addition to the seeds.
Seed banks are critical sources of new vegetation both in
pristine and impacted wetlands. Although characteristics of
the sediments play a role in the species type, composition, and
viability of seed bank species, the hydrologic patterns in the
wetland may be equally or more important (Schneider and
Sharitz, 1986). The significant role of hydrology in controlling
seed bank dynamics has important implications for the status
and restoration of some wetlands. Anthropogenic changes to
the wetland hydrology can alter a major mechanism for
sustaining the diversity and abundance of wetland vegetation.
Leek and Graveline (1979) found that annuals
were more prevalent than perennials overall,
although some perennials (e.g., Typha latifblia)
may dominate perennial numbers. They found
the species numbers decreased with soil depth
although the surface layers had few seeds,
possibly reflecting environmental conditions
(e.g., tidal exchange, export of surface seeds
with debris); there was a more gradual decrease
of seeds with depth compared to upland com-
munities (which may reflect prolonged dor-
mancy and increased longevity of a tidal fresh-
water marsh seed bank); and there appeared to
be different germination requirements and
viability of the marsh vegetation as reflected in
the seed bank. Wienhold and van der Valk
(1989) found that the number and density of
vegetation species found in drained wetland
seed banks declined over time. Typha
angustifblia was the only emergent species
represented in the seed banks of wetlands which
had been drained for 70 years.
Schneider and Sharitz (1986) examined seed
bank dynamics of a cypress-tupelo swamp and
bottomland hardwood communities. They
found dissimilar seed bank compositions
between the two communities both prior to and
following the first winter flood. After the flood,
however, the appearance of Acer rebrum and Itea
virginica seeds in the cypress-tupelo seed bank
caused an increase in similarity. Acer rubrum
produces samaras which are dispersed initially
by wind and are relatively short-lived. The
investigators concluded mat the presence of
Acer rubrum in the cypress-typelo swamp
samples after the flood was due to dispersal by
flood waters and wind. Unlike the results from
the freshwater tidal and nontidal marsh studies,
the woody seed banks of the two communities
did not reflect the standing floristic compositions
The herbaceous seed banks of both communities*
were similar, however, with the seed banks more
diverse in species composition than the standing
vegetation.
Utilizing a seed bank from a project wetland may
offer a more successful means of establishing the
wetland vegetation communiry(ies) at the
replacement site. The previous studies show that
seed banks are variable, however, and a thor-
ough examination of both the seed bank from the
project wetland and the environmental condi-
tions affecting germination from the seed bank
(particularly the hydrologic core factors) is
required prior to implementing compensatory
mitigation efforts (van der Valk 1992).
lB2(c) Vegetation Evaluation. Merely noting the
presence of a few plant species from the project
wetland does little to indicate the eventual
vegetation community(ies) that will develop at
the replacement site. In addition to either
describing or conducting a statistical sampling of
community dominants from each vegetation
strata present, an evaluation of the plant commu-
nity should also include the number and distri-
bution of federal or state-listed endangered and
threatened plant species. Such an assessment
will trigger coordination between the project
proponent and the VS. Fish and Wildlife Service
pursuant to the Endangered Species Act. Other
state natural heritage listed species which do not
fall into one of the preceding status categories
should also be noted. Other factors to consider
include: an estimate of the age or developmental
stage of the vegetation community; microsite
types and abundance (refer to the micro-relief
discussion above); and seed bank composition,
relation with soil depth, and utility at the replace-
ment site (e.g., can the seed bank be used, should
it be augmented with other species and why,
what conditions at the replacement site preclude
the use of the project wetland community seed
bank, etc.). In addition, geomorphic features and
hydrologic core factors need to be incorporated
in the evaluation of project wetland vegetation
dynamics to serve as the template for the replace-
ment site. In circumstances where the project
wetland does not serve as the model for the
replacement effort, an evaluation of the vegeta-
tion, geomorphic, and hydrologic characteristics
of an adjacent wetland community (or from a
population of reference wetlands) is suggested.
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21
1C LANDSCAPE SETTING
This factor refers to the spatial relation of the
(project wetland community and the replacement
site within the landscape and how this relation-
ship affects the hydrologic core and structural
factors of the project wetland for implementa-
tion at the replacement site. The surrounding
landscape and project wetland community
interact in the exchange of materials, energy,
and biotic forces. Wetland ecosystem processes,
functions, and values provided by the project
wetland are a reflection of the structure and
function of the surrounding landscape.
The boundaries of the landscape setting evalua-
tion should incorporate some hydrologically
defined area, such as a subwatershed or water-
shed (Gosselink and Lee 1989). Components of
the evaluation include the spatial relationship of
terrestrial, aquatic, and other wetland communi-
ties with land use features. For example, the
evaluation of a project wetland might include
the following assessment:
The project wetland occupies approximately
one-tenth of a contiguous forested wetland
ecosystem that extends three miles longitudi-
nally and 1,000 feet laterally along a third-order
stream. The forested wetland system occupies
ipproximately 27% of the drainage area of the
third-order stream and represents the largest
intact forest within the watershed. The project
wetland community is contiguous with a
beaver-impounded scrub-shrub wetland down-
stream and is part of a mature forested wetland
community extending upstream. Wetland
communities altered by beaver are common
throughout the system. A drinking water
supply reservoir exists one-half mile down-
stream. The entire forested wetland ecosystem
borders farmed upland pasture and upland
forests. There is some low density residential
development in the forested uplands through-
out the watershed. All lots have septic systems.
A steep forested upland slope lies between the
project wetland and farmed upland. The
farmed upland is typically planted in com and
soybean with a three-year fallow period be-
tween. The fields are regularly fertilized with
inorganic fertilizers and periodically with
manure and sprayed with a commonly used
herbicide. Soil type within the project wetland
community is generally a sandy loam overlying
a two to five-foot thick clay loam subsoil. The
soil in the adjacent beaver wetland is a silt-loam
ith large amounts of organic material at the
soil surface. The adjacent forested slope has
draughty sandy soils. The fanned upland soils
adjacent to the forested slope are ajso sandy but
have a higher percentage of silt. Approximately
one-third of the stream/wetland association
above the project wetland community has been
fenced to prevent livestock entry into the stream
and wetlands although there is no fencing
downstream. Close to 30% of lands housing
livestock upstream of the project wetland have
on-site animal waste management. Only 2% of
downstream farms have on-site animal waste
treatment. The forested wetland system is
hydrologically driven by shallow groundwater,
overbank flooding, and by overland flow in the
headwaters. The project wetland is predomi-
nantly groundwater driven and receives water
input from a seepage along the forested upland
slope. It is also infrequently flooded by overbank
flow.
The previous example represents a minimum
evaluation of landscape setting. More indepth
analyses of spatial relationships throughout a
landscape will require use of a Geographic
Information System (GIS). While more costly and
time consuming in the short term, use of a GIS to
identify compensatory sites, as well as determine
impacts to wetlands within a landscape context,
will provide a more comprehensive and ecologi-
cal sound approach in the long term.
Inclusion of the landscape setting for the project
wetland and the replacement site will broaden
the spatial component of the compensatory
mitigation efforts. Analyzing the hydrologic core
and structural factors at the landscape scale will
enhance the understanding of wetland ecosystem
properties and result in more ecologically sound
management decisions affecting compensatory
mitigation.
Variable 2: Identification of wetland ecosystem
processes and functions, and wetland values
2A. ECOSYSTEM PROCESSES
The hydrologic core and structural factors
identified above are responsible for processes
which are identifiable at the ecosystem level.
Hydrology is the predominant factor defining the
ecosystem processes within wetlands, including
organic matter production and decomposition,
energy flow, and biogeochemical cycling and
transformation (Table 1). Appendix C provides a
summary of technical information regarding
these wetland ecosystem processes.
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22
Process
Organic Matter Production
Organic Matter Decomposition
Energy Flow
Table 1. Selected Wetland Ecosystem Processes.
Description
Ability of vascular plants, primarily macrophytes, and algae to fix carbon via
photosynthesis, producing a usable organic energy source for heterotrophs. Typi-
cally measured as g dry wt/m2/yr as primary productivity. Basis of most aquatic,
wetland, and terrestrial food webs.
Processing and reprocessing of plant material by chemical.and biological processes
for assimilation by invertebrates and vertebrates in aquatic, wetland, and terrestrial
systems. Production of detritus (decomposing plant matter) provides substrate for
further conversion of organic carbon to assimilative forms. Basis of detritat food
webs.
Detrital or grazing trophic pathways may dominate, but many wetlands exhibit a
complex interaction of both. Trophic structure dynamics (i.e., "whom" eats "whom,"
when, where, and how often) frequently involve aquatic, wetland, and terrestrial
organisms, including humans.
Nutrient Cycling and Transformation
•
Cycling and transformation of nutrients is biologically, geologically, hydrologically,
seasonally, and climatically mediated. Whether any particular wetland is primarily a
source, sink or transformer of nutrients depends on the previous variables, as well as
landuses which affect those variables. Generally, wetlands appear to function as
sinks for various inorganic nutrient forms, sources of organic materials to down-
stream and adjacent systems, or transformers of inorganic inputs to organic forms for
export.
2B. ECOSYSTEM FUNCTIONS
Wetland ecosystem processes can be categorized
into wetland ecosystem functions. Table 2
presents examples of wetland ecosystem func-
tions, specific ecosystem processes associated
with the function, and resultant societal values.
Several wetland functional assessments in use
today do address ecosystem processes indirectly
(e.g., "trophic chain support" or "organic matter
export"). The assessments, however, do not
reflect the degree to which the ecosystem pro-
cesses operate within any given wetland. Rather
they are surrogates that gauge the relative
importance of that particular process or function.
The measurements produced by quantitative
assessments determine whether a compensatory
mitigation project closely approximates the lost
functions and values of an altered wetland. As
Kusler and Kentula (1989a) state:
_ {the} authors and informed contributors
continually affirmed that the creation and
restoration of wetlands is a complex and often
difficult task. This in turn, pointed to the
need for setting dear, ecologically sound
goals for projects and developing quantitative
methods for determining if they have been
met To validate the goal setting process,
wetland science must progress and the role of
wetlands in the landscape must be under-
stood. Only then can one truly evaluate which
ecological functions of naturally occurring
wetlands are provided by created and restored
wetlands.
Existing wetland ecosystem assessments are
primarily qualitative regarding function. While
they are intended to provide a means to assess
attributes which may reflect wetland ecosystem
functions, sufficient quantitative data generally
do not exist for every wetland type to assess
those attributes confidentially. In addition, there
is no single synthesis of existing data for Chesa-
peake Bay wetland systems which would aid in
modifying existing assessments.
2C. WETLAND VALUES
Wetland values are defined as the goods, services,
and benefits provided by a particular wetland
community or ecosystem, reflecting the unique
hydrologic core and structural factors, ecosystem
processes, and functions of wetland systems. The
following are examples of wetland ecosystem
values (adapted from Adamus and Stockwell 1983):
• Passive and active recreation areas
• Archeological, historic, or unique geologic
features
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23
1 Aesthetics *
Education
Scientific research
Fish, wildlife, and endangered, threatened,
and rare species habitat
• Harvesting of wetland foods, fibers, and, plant
or animal products (e.g., pelts, skins, chemi-
cal/medicinal products)
• Rood storage and desynchronization
• Shoreline/sediment stabilization
• Water quality maintenance or enhancement
• Base flow augmentation (groundwater dis-
charge)
• Drinking water source (groundwater re-
charge)
Compensatory mitigation plans should include
measures to replace the values of the project
wetland at the community and landscape scales.
Unfortunately, the scientific data base docu-
menting wetland ecosystem properties in the
Chesapeake Bay is limited, particularly for
nontidal wetland systems. Existing wetland
"functional assessments" ultimately rely on a
literature base that may not represent Chesa-
peake Bay wetland systems. To assess systems,
geographically relevant information is critical.
For example, extrapolation of information on
hydroperiod dynamics from Mississippi alluvial
bottomlands to periodically inundated, season-
ally saturated forested wetlands on the lower
Coastal Plain of Virginia may inaccurately
assess hydrologic functions for the Virginia
wetlands.
It is, therefore, difficult to assess values for
Chesapeake Bay wetland systems and to de-
velop compensatory mitigation plans that
attempt to replicate the values identified for the
project wetland. The identification and quantifi-
cation (where feasible) of the hydrologic core
and structural factors of the project wetland will
increase the likelihood that the compensatory
mitigation site will approximate the values of
the project wetland. The collection of baseline
data should be integral to the development of
any compensatory mitigation plan.
2D. WETLAND ASSESSMENTS
It is important to document accurately the
specific hydrologic core and structural factors,
functions, and values of the project wetland
rather than evaluate the wetland superficially.
For example, forested wetlands provide habitat
for species requiring trees for survival (e.g..
Table 2. Examples of wetland ecosystem functions, processes, and values.1
Ecosystem Process
Identified Function
Resultant Value
• Biogeochemical Interactions
• Organic Matter Production
• Decomposition Dynamics
• Hydroperiod/Hydrologic
Energy Source and Direction
• Alluvial Deposition/Erosion Patterns
• Biotic Diversity
> Recreation
• Scientific Study
• Education
• Aesthitics
• Sustenance
• Commercial Harvesting
• Landscape Heterogeneity
• Biogeochemical Interactions
• Hydroperiod/Hydrologic Energy
Source and Direction
•Alluvial Deposition/Erosion Patterns
• Nutrient
Cycling/Transformation
Mechanisms
• Drinking Water Supply
• Recreation ("Fishable" and
"Swimmable" Waters)
• Wetland Ecosystem Maintenance
• Biogeochemical Interactions
• Hydroperiod/Hydrologic Energy
Direction and Science
• Organic Matter Production
• Decomposition Dynamics
• Energy Flow Pathways
•Trophic Structure
Support
• Commercial Harvesting
• Consumptive and Nonsumptive
Recreation
»Landscape Integrity
'(Adapted from information provided by Jean O'Neil, USCOE-WES, Vicksburg, MS.)
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24
barred owl, red-shouldered hawk,* and prothono-
tary warbler). A herbaceous wetland community
does not meet the needs of such forest-dwelling
species. While both wetland communities
provide habitat, the hydrologic core and struc-
tural factors for each wetland community are
very different and support different faunal
communities (vegetation structure is obviously
different, but so too are the hydrologic core and
other structural factors). While replacement of
the project wetland community with a herba-
ceous wetland may be more easily accomplished,
establishing "success" remains problematic.
Rationalizations of improved "community
diversity" are often put forward with little
substantiation. In the example just outlined,
development of the compensatory mitigation
plan should include measures to replace the
destroyed forested wetland community over
time. Such a plan may necessitate the natural
reestablishment and development of the plant
community from a herbaceous assemblage to a
community dominated by woody species. The
ultimate goal is the establishment of a forested
system that is similar to the altered one. The
guidance in this document suggests using the
project wetland as the model for the replacement
wetland.
Presently, various qualitative and quantitative
function and value assessments are in use, such
as Wetland Evaluation Technique - Part II
(Adamus et al. 1991) and Habitat Evaluation
Procedures (U.S. Fish and Wildlife Service 1980).
Such assessments are usually applied to large
wetland tracts or when the potential for signifi-
cant wetland impact exists. Some computer
models of water quality and flood events may
also be useful in the assessment of wetland
ecosystem values. The existing assessment
techniques are not designed to evaluate cumula-
tive impacts, including the ramifications from
existing compensatory mitigation practices.
Development of more sensitive wetland ecosys-
tem assessment tools is necessary, along with
significantly more research on the values of
Chesapeake Bay wetland systems. The science
and technology of wetland ecosystem assess-
ments will generally lag behind the information
requirements necessary for effective wetland
management. Therefore, federal and state
agency field personnel should assess and docu-
ment wetland ecosystem functions and values for
all wetlands potentially affected by a proposed
project. Such an interagency evaluation may use
qualitative or quantitative assessments or
professional judgement to provide such docu-
mentation. More in-depth quantitative analysi
may be required, particularly if the project is
controversial or significant impacts are likely.
Furthermore, efforts should ensure the utility
and compatibility of data gathered to expand
the base data. Table 3 presents various wetland
ecosystem values and identifying criteria which
may be helpful in evaluating minor impacts or
where an in-depth assessment of wetland values
is not possible due to time constraints.
Significant uncertainties remain regarding the
feasibility of replacing wetland ecosystem
processes, functions, and values (Moy and Levin
1991; Kusler and Kentula 1989a). Scientists lack
a basic understanding of many of the ecosystem
processes operating in wetland systems, the
interactions with adjacent systems within a
landscape, and the effect of human activities on
wetland ecosystem properties in the short or
long term. Qualitative assessments give a small
and incomplete measure of the complexity of
wetland ecosystems. From this information,
combined with hydrologic core and structural
baseline data, the type of wetland community to
replace and the required acreage are deter-
mined. Until better function and value assess-
ment tools based on scientific measurements are
available, the most appropriate course of action
is to replace unavoidable wetland ecosystem
losses on an acre-for-acre basis. This acre-for-
acre replacement is a minimum value. Where it
is determined that more than a 1:1 replacement
is necessary (e.g., based on a lack of demon-
strated "success," enforcement proceedings, or
state permit regulations), there should be a
sufficient water source and water supply given
the existing water uses of the replacement site
(Clewell and Lea 1989a).
2E. REFERENCE WETLANDS
A relatively recent concept in compensatory
mitigation efforts is the application of "refer-
ence wetlands" (Pacific Estuarine Research
Laboratory 1990). Reference wetlands are a
population of wetlands, including wetland
communities, which exhibit some degree of
disturbance. Reference wetlands serve several
purposes relative to compensatory mitigation
efforts:
• They may provide baseline data when project
wetlands have already been lost but develop-
ment of compensatory mitigation plans has
not occurred or been approved. The popula-
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25
Value
Erosion Control
Table 3. Wetland Values and Identifying Criteria
(adapted from Maryland Soil Conservation Service unpublished guidelines,
VIMS 1991, and Adamus et at. 1987).
Criteria
Wetland is located in a landscape position where it protects the soil from
erosion caused by concentrated surface flow, overbank flooding, or
wave action.
Sediment Control
Floodwater Storage and Flow
Reduction*
Water Quality Maintenance and
Enhancement
Migratory Bird Habitat
Endangered, Threatened, or Rare
Species Habitat
Upland Wildlife Habitat
Wetland Wildlife Habitat
Finfish Habitat
-Areas of Special Concern
Wetland is located in a landscape position which is adjacent to or
downstream of sediment sources, including Highly Erodible Land where
conservation practices are not in use; the wetland topographic gradient
is gradual; and/or the wetland is forested or otherwise heavily vegetated.
Wetland is characterized by presence of very sinuous channels within the
vicinity of the wetland, dense vegetation, watershed slope of at least 3%,
presence of vegetation with rigid stems (e.g., trees, shrubs, cattails), and/
or 1-foot or more of water is impounded during flood events.
Wetland is adjacent to sources of nutrients and pollutants such as
cropland, active pastureland, barnyards, manure storage areas, urban
lawns, golf courses, sewageoutfalls, dumps/landfills, defective septic
fields or those built on wet soils, lands denuded of vegetation, or
urbanized areas such as commercial parking areas.
The wetland provides or would provide feeding, nesting, resting, or cover
habitat for migratory birds, including songbirds, raptors, wading birds,
ducks, geese, swans, or other birds protected by Federal Migratory Bird
Treaty laws.
The wetland contains or is likely to contain habitat for Federal or state
listed plants and animals.
The wetland provides breeding, nesting, feeding, or cover habitat for
upland wildlife such as deer, pheasant, wild turkey, eastern cottontail,
black bear, woodcock, bobwhite quail, etc.
The wetland provides breeding, nesting, feeding, and cover habitat for
wetland wildlife species such as otter, beaver, muskrat, nutria, marsh
rabbit, mink, green frog, spring peeper, painted turtle, brown snake, four-
toed salamander, etc
The wetland is flooded at a sufficient depth and duration, and is
connected to surface water (i.e., stream, river, lake/reservoir, or the Bay)
which provides breeding, nursery, and/or feeding areas.
The wetland is located within an area designated by Federal, State, or
local government agencies as requiring particular landuse provisions
(e.g., Maryland's Critical Area law, Virginia's Chesapeake Bay Preserva-
tion Act, Executive Order 11988 - Floodplain Management and the
Floodplain Management Guidelines (£K 43(29) 1978); the wetland is
designated as an important natural resource area (e.g., NOAA designated
Estuarine Reserve); or the wetland is immediately adjacent to other
protected lands (e.g.. National Wildlife Refuge System, State wildlife
management area, land owned by a conservation organization).
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26
tion of reference wetlands should provide
baseline characteristics similar to the project
wetlands unless the goal of replacement is not
structural and functional equivalency. For
example, using ten salt marsh communities to
replace coastal forested flats in southeastern
Virginia would not be an appropriate reference
wetland population if the goal is to replace the
structure and function of die forested coastal
flats.
• Where baseline data are collected, such data
provide snapshots through time particularly
when hydrologic information is lacking. A
population of reference wetlands can supple-
ment the data base.
• A population of reference wetlands serves as a
means of adjusting monitoring criteria for
compensatory mitigation efforts underway.
• Reference wetlands serve as "living laborato-
ries" providing quantitative measurements of
wetland ecosystem structure, processes, and
functions. They also help identify the benefits
provided by a variety of wetland systems
within a landscape, enhancing management
decisions so that landscape integrity can be
maintained relative to wetland ecosystem
properties.
• Reference wetlands also serve as a useful tool in
refining compensatory mitigation site selection,
design, and success criteria.
To date, there has not been a systematic identifi-
cation and incorporation of reference wetlands
into mitigation efforts throughout the Chesapeake
Bay watershed. As a result of the June 1993
wetlands compensatory mitigation workshop in
Arnold, Maryland, however, a concerted effort is
underway to identify reference wetlands, test the
applicability of the reference wetland concept,
and design an implementation strategy for
forested wetlands on the Mid-Atlantic Coastal
Plain. This effort should assist in identifying
additional reference wetland populations
throughout the Chesapeake Bay region.
Variables: Identification of types of compensatory
mitigation
Once the baseline data for the project wetland have
been gathered and analyzed, the specific type of
compensatory mitigation should be determined by
the federal and state regulatory and review agencies.
A project sponsor or consultant acting on behalf of
the project sponsor can still present information on
a replacement site or sites and this is strongly
encouraged. For the regulatory and review agen-
cies to evaluate compensatory mitigation plans in
an ecological context, however, it is important to
consider variables four through eight. Application
of these variables must rest with the public agen-
cies which comment on and approve the activities
in question and the attendant compensatory
mitigation efforts. The entire site-selection process
(i.e., variables one through eight) should be an
iterative process.
Kruczynski (1989b) identified and discussed the
application of four types of compensatory mitiga-
tion: restoration, creation, enhancement and
preservation. These concepts, with some modifica-
tion, are presented below.
3A.RESTORATION
Restoration refers to the reestablishment of a
wetland community with hydrological modifica-
tions in an area where wetlands previously
existed in the same general topographic location.
Hydric soils may continue to characterize the
former wetland site, although the soils may exist
in an altered form (e.g., buried, oxidized,
drained). Restoration is an evolving science and
requires experts who understand and can
manipulate a site to reestablish wetland hydrol-
ogy. The relative potential for success is high
because only one or a few physical conditions
need to be altered or manipulated.
3B. CREATION
Creation involves the establishment of a wetland
community where one did not formerly exist.
Creation usually occurs in terrestrial environ-
ments but it has also taken place in open water.
Creation, like restoration, requires knowledge of
wetland hydrology. Unlike restoration, creation
generally involves the manipulation of terrestrial
environments to establish wetland hydrology.
The site soil conditions do not usually exhibit
hydric soil characteristics as determined by
texture, organic profiles, and other properties.
Creation is a more difficult process than restora-
tion and requires extensive pre-planning to
select the appropriate location and ensure the
proper elevations and water supply for establish-
ment of the hydroperiod. Creation often re-
quires more monitoring and follow-up than
restoration.
3C ENHANCEMENT
Enhancement is any activity conducted within
an existing wetland community that manipulates
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27
one or more physical characteristics of the site to
increase one or more wetland functions and/or
lues. Enhancement differs from restoration in
>t it occurs in existing wetland communities.
While enhancement often benefits specific wetland
ecosystem functions and values, it involves trade-
offs between wetland ecosystem structure, pro-
cesses, functions, and values. Enhancing one
wetland function or value may negatively affect
others. Evaluating when and where enhancement is
ecologically appropriate requires consideration
within a landscape context.
3D. EXCHANGE
Exchange is an extreme type of enhancement
which typically involves trading one wetland
vegetation community type for another
(e.g.,replacing a forested wetland with a marsh).
It can also include replacing wetland communities
of different hydrologies (e.g., replacing a tidal
marsh with a nontidal marsh or a riverine swamp
with a vegetated pond). Exchange may result in
an ecologically functioning replacement wetland.
However, the new wetland community may not
provide the site or landscape-specific functions
that were provided by the project wetland com-
munity. Implementing exchange, particularly as
a standard mitigation practice, will result in
ulative effects to adjacent systems and the
s and values they provide. As
Kruczynski (1989b) cautions, "Exchange should
only be used when there is ample scientific
evidence demonstrating that the functions of an
ecosystem or region are limited by the lack of a
particular community type." In other words,
there should exist an ecological void that must be
filled for an ecosystem or region to demonstrate'
ecological integrity.
3E. PRESERVATION
Preservation of existing wetland communities via
monetary or land donation is generally an unac-
ceptable form of compensatory mitigation when
associated with the federal regulatory program.
Many significant activities in existing wetland
communities are regulated through the federal
permitting program and some form of protection
is usually afforded. Additionally, to achieve the
no-net-loss goal in the Chesapeake Bay drainage
through federal and state programs, the replace-
ment of all wetland ecosystem losses is necessary.
The purchase or donation of existing wetland
communities in lieu of wetland replacement
results in a net deficit of wetland community
^•Acreage and ecosystem functions and values.
^^•urthermore, the source of funds (e.g., new vs.
preexisting) is not easily tracked and potentially
subject to abuse. The key to protecting existing
wetland systems rests with avoiding alterations,
acquiring or purchasing long-term easements
for both wetland systems and adjacent uplands
in perpetuity, and eliminating land practices
which result in wetland ecosystem degradation.
Compensatory mitigation plans should con-
sider, in order of preference: restoration, cre-
ation, and enhancement. Because the site-
selection process is intended to be dynamic, this
ordering may not be appropriate in all circum-
stances. Agencies, however, are encouraged to
document why the suggested order is not
applicable in specific cases.
The decision to select restoration, creation, or
enhancement is based on a variety of factors
including the probability of success for each
type of compensatory mitigation as well as the
land available. Documenting baseline data for a
project wetland prid to its alteration, designing
compensatory mitigation plans using the
baseline data from the project wetland, and
implementing the guidance contained in this
manual will enhance the probability of func-
tional replacement success.
Variable 4: Identification of in-kind and
out-of-kind replacement
4A. IN-KIND REPLACEMENT
Closely replicating the hydrologic core and
structural factors, ecosystem processes, func-
tions, and values of a project wetland is referred
to as "in-kind" compensatory mitigation. In-
kind replacement reflects hydrological, struc-
tural, and functional equivalency of the project
wetland community. Achieving hydrological,
structural, and functional equivalency involves
replacing as many of the specific hydrologic
core and structural factors, ecosystem processes,
and functions of a project wetland as possible.
A prime goal is to maintain the values provided
by the project wetland as well as achieve no-net-
loss of wetland resources throughout a land-
scape. Hydrologic core and structural factors as
well as ecosystem processes and functions of
any two wetland communities differ to some
degree. Along the continuum of wetland
structure and function, the closer the specific
structural characteristics and functions of one
wetland to another, the closer one approaches
in-kind wetland replacement.
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There are circumstances, however, in which
attempting hydrological, structural, and func-
tional equivalency of the project wetland may not
be ecologically sound. One example is replicating
wetland communities impacted by toxic runoff
(i.e., degraded wetlands). In other cases, human
activities have so disturbed the hydrology that
the wetland does not function as it did originally
and associated values are disrupted or nonexist-
ent (e.g., farmed wetlands).
As with any type of wetland ecosystem compen-
satory mitigation effort, it is important to assess
ecosystem functions and values and document
hydrologic core and structural factors of de-
graded and highly disturbed wetland communi-
ties, so a factual evaluation of replacement can
proceed. In such cases, the ecologically correct
approach may be to determine the "potential"
wetland ecosystem properties (i.e., hydrologic
core and structural factors, ecosystem processes,
functions, and values) of the project wetland
without the impact. The potential then serves as
the targeted site-selection variables of the com-
pensatory mitigation plan. In-kind replacement
refers to the potential ecosystem properties of the
project wetland community without the effects of
the current impactfsV
For example, seepage from a pesticide manufac-
turer has impacted a 10-acre forested wetland for
10 years. An evaluation shows that a proposed
roadway will affect 4.7 acres of the forested
wetland community. Analysis of soil, water,
vegetation, and wildlife (invertebrates and
vertebrates) indicates that the site is contami-
nated from leaching of the pesticide. Both a
recovery plan to restore the wetland system and
a compensatory mitigation plan for the loss due
to the roadway are developed. Compensatory
mitigation for the 4.7-acre road impact area is
based on the potential ecosystem properties of
the project wetland had it been unaffected by
pesticide runoff. The mitigation plan required
siring the replacement site adjacent to the newly
rehabilitated forested wetland ecosystem. In this
example, the emphasis is on the roadway impact.
Ideally, the development of compensatory
mitigation efforts and remedial actions due to
contaminant issues (e.g., Superfund sites) should
be coordinated to avoid cross-purpose goals that
may inhibit completion of either action.
Continuing with the example above, it is impor-
tant to use baseline data from the project wet-
land, such as the geomorphic setting,
hydroperiod, nutrient supply, and adjacent land
uses/covers to determine wetland community
potential. Reviewing aerial photography taken
prior to and during operation of the pesticide
plant may identify some of the potential hydro-
logic core and structural factors. Compiling an
information base with current and historical data
provides the framework for designing the
compensatory mitigation plan for the 4.7-acre
wetland community loss. There may be enough
information to easily determine whether in-kind
replacement is feasible; if not, one must use best
professional judgement to evaluate all the
available information to proceed. "Out-of-kind"
replacement may be the only feasible approach
in the long term, or an initial out-of-kind replace-
ment with the goal of eventual in-kind replace-
ment may also be an option.
It is very difficult to replace wetland losses in-
kind. In situations where the wetland commu-
nity is dominated by seemingly "simple" and
easily replicated hydrologic core and structural
factors (e.g., regularly-flooded Spartina
alterniflora marsh), evidence of in-kind replace-
ment may not initially be apparent. Even in
instances of the complete establishment of
vegetative cover for such "simple" communities,
some structural components may not have been
developed or were not considered. The nutrient
supply may be different so that nutrient cycling
and primary and secondary productivity path-
ways are significantly different from either the
project or reference wetlands. To attempt
ecological replacement of lost wetland ecosys-
tems, document the baseline data for either the
project wetland or the reference wetlands is
critical. If in-kind replacement is not ecologically
or physically practical the reasons must be
documented. Until a concerted effort is made to
achieve ecological integrity and document the
mitigation process, mitigation efforts will be
ineffective. Adherence to the best scientific
information and careful documentation of efforts
to replace wetland ecosystems should be the
guiding principles. Measures of "success" are
only valid in this context.
4B. OUT-OF-KIND REPLACEMENT
Out-of-kind compensatory mitigation refers to
the replacement of the project wetland with one
which is not hydrologically, structurally, and
functionally equivalent or which is not so
initially (particularly in cases involving wetland
creation). Out-of-kind mitigation may also
utilize another habitat type (e.g., non-wetland)
which may not provide comparable wetland
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I
In-Kind vs Out-of-Kind Replacement
In-kind replacement refers to the use of a hydrologically,
structurally, and functionally equivalent wetland community as
a substitute for the impacted project wetland. To achieve this
equivalency, the replacement community should duplicate as
many of the specific hydrologic, core and structural factors,
ecosystem processes, and functions of the project wetland as
possible. Such an effort maximizes the chance of transferring
the values and functions of the project wetland to the replace-
ment site while also achieving the no-net-loss goal.
In most cases, in-kind replacement is preferred over the alter-
native—out-of-kind replacement—since it attempts to closely
simulate the original site. Out-of-kind replacement is the cre-
ation, restoration, or enhancement of a project wetland with a
wetland that is not structurally and functionally equivalent (or
is not so initially) or with another habitat type which may not
provide wetland structural and functional equivalency. Certain
circumstances, however, dictate the use of out-of-kind replace-
ment as an alternative, particularly when the project wetland is
so degraded that the wetland is non-functional and provides
little or no value to society.
ecosystem properties. Generally, out-of-kind
compensatory mitigation includes: the establish-
ment of different wetland vegetation communi-
; the establishment of a different hydrologic
; use of a substrate deficient in organic
; location of the compensatory mitigation
site in a topographic location different from that
of the altered wetland; or application of practices
which affect other landscape features, such as the
stabilization of eroding stream banks or the
enhancement of an upland woodlot for deer
management. Out-of-kind compensatory
mitigation involving non-wetland ecosystems is
considered inappropriate. The achievement of
the no-net-loss goal of Chesapeake Bay wetland
acreage, functions, and values is not possible
using this type of compensatory mitigation.
Hydrologic and geomorphic site selection variables
are key factors in evaluating in-kind or out-of-kind
options. Early evaluation of these variables will, in
large measure, control the replacement wetland
community in terms of vegetation structure,
processes, functions, and values.
If the hydrological core factors differ significantly
from those at the project wetland, many other
site selection variables, including vegetation
community dynamics, biogeochemical dynamics,
and the values and functions provided by the
Toject wetland, will be affected. For example,
etland communities located within a riparian
corridor are affected by stream hydraulics
(e.g., overbank flow rates and duration,
sediment deposition, and scouring),
whereas other wetland communities are
more affected by groundwater, direct
precipitation, and surface runoff. The
hydrologic core factors of the two commu-
nities are different. As result, these con-
taminants exhibit different ecosystem
properties. .Riparian wetland communi-
ties are generally more free-flowing
systems in the exchange of materials,
energy, and biota than nonriparian
wetland communities. The two wetland
systems result from different geomorphic
settings. The replacement of a riparian
wetland community with a wetland
situated in a dissimilar hydrogeomorphic
location results in out-of-kind compensa-
tory mitigation.
In other scenarios, the vegetation structure
may not adequately reflect ecosystem
processes (e.g., when the hydroperiod has
been altered but vegetation has not significantly
changed). Ecosystem processes, such as
biogeochemical cycles, may have also changed
because of the relationship between the
hydroperiod and these processes. For example,
Whigham (1992) found only minor differences
between upstream and downstream wetland
vegetation communities in relation to growth
patterns, composition, and biomass (i.e., litter
production). Due to road construction across
the wetland communities, however, the
hydroperiod differed greatly between the two
sites and caused significant differences in soil
and leaf litter nitrogen levels and decomposition
rates. Such differences in ecosystem processes
may result in functional differences, such as
nutrient cycling, which may affect downstream
water quality or the trophic structure of the
adjacent aquatic community.
4C OUT-OF-KIND REPLACEMENT EXAMPLES
In many instances, an applicant or agency
representative proposes the replacement of one
vegetated wetland community type with
another. If the goal of compensatory mitigation
efforts is to strive for hydrological, structural,
and functional equivalency, however, this
cannot be achieved by trading vegetated wet-
land types. Where management considerations
dictate other courses, such actions should be
carefully considered from a landscape perspec-
tive to retain the overall goal of no-net-loss.
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30
Circumstances which routinely involve replacing
one vegetation community with another include:
1) Exotic or invasive species dominate one or
. more vegetation strata in the wetland com-
munity;
2) Hydrophytic vegetation is virtually absent
due to disturbance (e.g., farmed wetlands,
cleared or other disturbed sites where all or
most of the wetland vegetation has been
eliminated); or
3) Forested wetland community losses are to be
replaced.
The following examples illustrate out-of-kind
compensatory mitigation involving an invasive
hydrophytic plant species, fanned wetlands, and
replacement of forested wetlands.
4C1. Phragmites australis Wetland Replacement
Replacement of a regularly flooded intertidal
wetland vegetated with common reed (Phragmites
australis) is required. A native plant community
is proposed rather than reestablishing Phragmites
(a typically invasive species which often results
in monorypic stands). If the Phragmites wetland
is located in a salinity regime compatible with the
establishment of saltmarsh cordgrass (Spartina
alterniflora), this out-of-kind change is acceptable
since the intertidal cordgrass replacement
community is a herbaceous wetland, the hydro-
logic regime is the same, and the substrate may
be similar. These factors reflect structure which
in turn reflects wetland function and ultimately,
wetland values.
4C2. Farmed Wetland Replacement
Replacing farmed wetlands4 as a result of un-
avoidable losses will generally involve out-of-
kind replacement, particularly if the wetland site
is actively fanned (i.e., it only lies fallow during
rotational cycles or during very wet years).
Compensating for farmed wetland losses should
not involve only the creation of predominantly
open-water habitats (e.g., wildlife/waterfowl
ponds, stormwater management ponds, etc.) or
the enhancement of existing wetlands for such
purposes. The most acceptable action is to
reestablish, as closely as possible, the original
hydrology of a hydric soil in a cropland field and
then allow reestablishment of the natural hydro-
phytic vegetation. Agricultural wetlands which
are not actively cropped and are vegetated by
hydrophytes are, by definition, "natural" (i.e.,
vegetated) wetlands and must be replaced
accordingly.
4C3. Forested Wetland Repalcement
A considerable time span is required to replace
forested wetland communities. Appropriate
choices of vegetation and hydrology and the use
of existing soils from the project wetland site
(where practical) are critical elements. Even with
the establishment of the appropriate type and
composition of vegetation, the newly planted
vegetative community will rarely resemble the
project wetland community in terms of age,
community structure, vigor, and growth potential
over the short term. Such wetland replacement is
considered out-of-kind because the vegetative
structure does not reflect the project wetland and
wetland ecosystem processes, functions, and
values will often differ between the two wet-
lands. Baseline data for the project wetland or a
population of reference wetlands provide the
information required for compensatory mitiga-
tion plan design and the implementation of
appropriate management needed at the site.
While out-of-kind compensatory mitigation
cannot be avoided for forested wetland replace-
ment, comprehensive site planning, diligent
implementation of the plan, and long-term
management and monitoring of the site can guide
the initial out-of-kind scenario towards in-kind
replacement.
4D. ACHIEVING IN-KIND REPLACEMENT
Many creation projects fall under the out-of-kind
compensatory mitigation category. Wetlands are
often created on upland sites where hydrologic
core and structural factors are not initially
present. To achieve in-kind replacement, these
factors from the project wetland must be incorpo-
rated into the design of the compensatory mitiga-
tion plan. Where feasible, appropriate structural
factors within the project wetland (e.g., the soil
and seed bank of the project wetland) should be
transplanted to the replacement site. The remain-
ing structural factors and hydrologic core factors
of the project wetland can then be mimicked to
achieve in-kind replacement.
4 'Farmed wetlands" are defined by the U. S. Soil Conservation Service as wetlands that are seasonally flooded or ponded (i.e., surface
water is present for at least 15 consecutive days or 10% of the growing season, whichever is less under average conditions) and have
been manipulated for commodity crop production prior to December 23,198S, but otherwise meet wetland criteria.
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Unfortunately, no means exists to easily
measure at what point in-kind replacement
jj^k achieved. Furthermore, because of the
^Rherent variability of wetland systems, in-
kind replacement is a process with differ-
ent variables contributing at different
stages. The use of reference wetlands
significantly improves the understanding
of the in-kind replacement process and
provide temporal bench marks to evaluate
the progress of the replacement site. To
achieve the no-net-loss goal for Chesapeake
Bay wetland systems, efforts to replace
wetland hydrology, structure, and function
must become the norm rather than the
exception.
rep
«:
i
Variable 5: Identification o/cm-site and
off-site locations
Typically, the issue of replacing a wetland
community either "on-site" or "off-site"
has been interpreted from a regulatory
perspective. Ecological reasons, however, under-
lie the regulatory interpretation. Ecological
replacement on-site or off-site is an extension of
drologic, structural, and functional equivalency.
leoretically, the closer the distance of the re-
icement site to the project wetland, the more
likely the replacement wetland will have many of
the same hydrologic core and structural factors.
The characteristics of the replacement site, includ-
ing local land use and the type of compensatory
mitigation, also influence whether an on-site
location will enhance in-kind replacement. In
some circumstances, an off-site location may
provide a more appropriate environment to
achieve in-kind replacement. Hydrogeomorphic
factors are key elements in evaluating a site for
wetland community replacement.
5A. ON-SITE LOCATION
The following general guidance is intended to
clarify the relationship between on-site and off-
site locations relative to in-kind and out-of-kind
replacements. To achieve no net loss, locating the
replacement wetland on-site is generally pre-
ferred. On-site locations are areas adjacent to the
project wetland which will likely replace the
ecological functions and societal values of the
project wetland. Landscape-level processes
throughout the watershed are then minimally
upted, particularly in cases where on-site
i is closely allied to in-kind replacement.
On-site vs Off-site Location .
On-site location of a replacement wetland community uses an
area adjacent to the project wetland which is more likely to
duplicate the functions and values of the impacted wetland. In
most situations, a site closer to the project wetland is more
likely to have similar hydrologic core and structural factors than
one that is further removed and enhance the possibility of
achieving in-kind replacement On-site locations also help fulfill
the no-net-loss goal and minimize disruption of landscape-
scale processes within the watershed.
On-site location is generally preferred over off-site location. It
is more important, however, to achieve in-kind replacement of
the project wetland; in some cases, off-site locations are better
suited to accomplish this goal. In these situations, the replace-
ment site is not adjacent to the project wetland. Off-site
locations may be chosen because on-site locations may not be
available, project wetland equivalency is more likely at an off-
site location, or the off-site location (where equivalency is
likely) benefits adjacent protected lands. Each case is unique
and the particular circumstances affecting a given site should
be well understood before choosing an on-site or off-site
location for wetland replacement.
5B. OFF-SITE LOCATION
A wetland community replaced off-site is
located in an area not adjacent to the project
wetland. Selection of an off-site location gener-
ally compounds the difficulty of replacing in-
kind. An off-site location may result in out-of-
kind replacement when the replacement site is
in the same watershed but in a different
hydrogeomorphk setting, (e.g., locating the
replacement wetland in a headwater, first-order
stream to replace a project wetland located
downstream in a third-order reach). Sites not
adjacent to the project wetland may be more
conducive to achieving in-kind replacement
than an on-site location.
In addition to site variables, the type of compen-
satory mitigation may further strengthen
selection of an off-site location. The following
considerations should assist in determining
when selection of an off-site location is ecologi-
cally appropriate:
(1) a thorough investigation shows on-site
locations are not available (note: selection of
an off-site location should still emphasize
hydrological, structural, and functional
equivalency); or
(2) the achievement of hydrological, structural,
and functional equivalency of the project
wetland would be more successful at the off-
site location (i.e., site conditions are more
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conducive to achieving in-kinfl replacement
than at an on-site location); or
(3) hydrological, structural, and functional
equivalency are met at the off-site location
and the compensatory mitigation site would
benefit natural resources on adjacent pro-
tected lands (e.g., a NOAA-designated
estuarine reserve, a site adjacent to Nature
Conservancy land, etc.).
5C CONSOUDATED COMPENSATORY
MITIGATION
In specific circumstances, such as the scale of a
project, on-site and off-site replacement site
constraints, or other limiting factors, the selec-
tion of an off-site location may be through the
use of "consolidated .compensatory mitigation"
(e.g., joint mitigation projects, combined wet-
land replacement, aggregated wetlands replace-
ment, mitigation banking, or watershed/
regional-level compensatory mitigation).
Consolidated compensatory mitigation is the
replacement of multiple wetlands losses result-
ing from several specific activities at one off-site
location. Typically, consolidated compensatory
mitigation locations are geographically defined
within a watershed, hydrologic unit, or physi-
ographic province, to replace the functions and
values lost in the defined area as a result of
these activities.
Possible sites for consolidated compensatory
mitigation should be hydrogeomorphically
defined and incorporate as many of the project
wetland site selection variables as possible. A
matrix comparing the site selection variables for
the project wetland and those present at the
consolidated replacement site will indicate
whether in-kind or out-of-kind replacement is
feasible. When out-of-kind replacement ap-
pears inevitable for the long term, the matrix
can be used to help design ecologically signifi-
cant wetland ecosystem replacement. If the
consolidated compensatory mitigation site is
selected for replacing wetland losses due to
multiple projects, this matrix should be evalu-
ated for each project wetland.
Several consolidated compensatory mitigation
sites within a landscape subunit (e.g.,
subwatershed) may be needed to maintain the
spatial and functional heterogeneity throughout
the landscape reflected by existing wetland
ecosystems. This approach requires an evalua-
tion of trends in land practices (e.g., increasing
infrastructure and subsequent development in a
subwatershed) and an assessment of the site
variables for those wetland ecosystems likely to
be affected by potential land practices within
subwatershed. The identification of suitable
consolidated compensatory sites throughout the
subwatershed is also necessary.
Developing a common suite of baseline character-
istics at a consolidated compensatory mitigation
site to reflect the multiple functions and values
provided by several wetland communities is very
difficult. If selected consolidated compensatory
mitigation sites exhibit only one or a few of the
functions and values of the project wetlands, then
quantitative measures of wetland ecosystems will
be critical for "managing" the Chesapeake Bay
watershed to ensure that a minimal range of
wetland ecosystem functions and values contin-
ues to exist throughout the landscape.
5D. SELECTION OF ON-SITE OR OFF-SITE
LOCATIONS
Determination of an on-site or off-site location is
not separate from in-kind replacement consider-
ations or from the selection of the appropriate
type of compensatory mitigation. Again, evaluat-
ing the "right" mix of site selection variables
should complement the dynamic processes
affecting wetland ecosystems. The key to select-
ing this mix is to strive for ecological integrity a*
the wetland community and ecosystems levels
and within a landscape context.
Variable 6: Identification of compensatory
mitigation timing
Kruczynski (1989b) identified three time periods
associated with compensatory mitigation imple-
mentation:
(I) Prior to permit issuance ("up front" compen-
satory mitigation);
(2) Simultaneous with carrying out the project
("concurrent" compensatory mitigation); and,
(3) After project completion ("post project"
compensatory mitigation).
6A. UPFRONT COMPENSATORY MITIGATION
Implementing compensatory mitigation up front
is most applicable when the impacts associated
with the project are significant, the project
wetland community is complex, or the ability to
replace that community is uncertain or unproven
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33
6B. CONCURRENT COMPENSATORY
MITIGATION
Concurrent compensatory mitigation is accept-
ble when up front compensatory mitigation is
not feasible or applicable. Since the timing
schedule of a compensatory mitigation may
pose problems, particularly meeting optimal
planting dates, some flexibility in permit
conditions may be acceptable. For example, the
Corps of Engineers or an appropriate state
regulatory agency can impose conditions on a
permit so that earthmoving associated with
wetland community creation can occur simulta-
neously with any appropriate phase of project
construction. Planting can be delayed until
weather conditions ensure maximum vegetation
survival.
6C POST-PROJECT COMPENSATORY
MITIGATION
Post-project compensatory mitigation is not
generally recommended since it is very difficult
to ensure permit compliance, ecological goals,
and no net wetland loss. If this type of compen-
satory mitigation is the only option, the permit
should include initiation and completion dates,
posting of a performance bond, and any other
necessary conditions. If the applicant does not
kcomply with the critical date, the Corps or
ippropriate state agency should initiate appro-
priate enforcement actions. Post-project com-
pensatory mitigation has historically failed to
prove that it can achieve no-net-loss goals.
Variable 7: Identification of lands amenable to
compensatory mitigation efforts
Land suitable for compensatory mitigation is
relatively scarce and often competed for by
other land use interests (e.g., residential devel-
opment, stormwater management, waterfowl
ponds, etc.). Locating compensatory mitigation
projects on land with topographic and/or other
physical conditions characteristic of wetland
systems will enhance the success of replacing
the wetland ecosystem hydrology, structure,
and function. In addition, the relevance of
locating the replacement wetland on-site or off-
site compared to in-kind or out-of-kind replace-
ment must be considered. The decision to select
a site for compensatory mitigation must incor-
porate these factors if the no-net-loss goal is to
be achieved. The following discussion provides
;eneral information on the kinds of lands that
may be appropriate compensatory mitigation
sites under the conditions discussed.
7A. PRIOR-CONVERTED CROPLANDS
Prior-converted croplands are common through-
out the lower Coastal Plain of Maryland and
Virginia. Two types of these croplands are
generally recognized. Some still function as
wetlands (i.e., the land has not been "effectively
drained"). Conversely, other prior-converted
croplands have been effectively drained and no
longer provide wetland functions and values. It
is often difficult to determine whether a prior-
converted wetland is effectively drained with-
out extensive hydrologic studies. Both types of
cropland, however, occupy topographic posi-
tions which increase the likelihood of successful
compensatory mitigation. Use of prior-con-
verted croplands for compensatory mitigation
is, therefore, encouraged. Restoration carried
out on prior-converted croplands has a high
probability of success.
7B. FORMER DREDGED MATERIAL
DISPOSAL SITES
Former dredged material disposal sites which
are not wetlands and are no longer used or
planned for use as disposal sites are also good
candidates as compensatory mitigation lands.
The amount of fill to be removed, location of
another disposal site, and the potential for
contaminated sediments are factors that must be
thoroughly evaluated before selecting dredged
material disposal sites as compensatory mitiga-
tion lands. In addition, some filled former
wetlands on federal and state lands no longer
serve the purpose for which they were filled and
should be identified as potential compensatory
mitigation sjtes. Former wetlands which were
unnecessarily altered (i.e., channelized streams
and concrete channels constructed for flood
control) are also potential sites for compensatory
mitigation. Many of these former wetland
communities exist on small streams in urban
settings and could be restored as greenways.
Along with vegetated buffers, these greenways
provide stormwater management benefits.
7C ENHANCING PHRAGMITES-DOMINATED
WETLANDS
Enhancement of existing wetland communities
is possible on several types of lands. Common
reed (Phragmites australis) wetland communities
are commonplace in the Chesapeake Bay
landscape; replacing this invasive hydrophyte
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with a vegetation community which existed
previously (e.g., Spartina alterniflora) is possible.
Intensive site manipulation and long-term
management of the site, and surrounding area,
however, may be necessary to ensure domi-
nance of the newly established wetland plant
community. These management measures must
be included in the compensatory mitigation plan
if common reed wetland communities are
selected as replacement sites.
7D. DEGRADED WETLAND COMMUNITIES
"Degraded" wetland communities are often
cited as prime candidates for compensatory
mitigation activities. Such sites are often altered
by toxic substances or other pollutants (e.g.,
water quality deterioration resulting from
increased mercury or other heavy metal load-
ings and subsequent burial within the wetland)
and no longer function adequately to provide
values to society. The degradation process is
usually the result of land use changes within the
watershed rather than a single causative factor.
Degraded wetland communities can often be
enhanced, although compensatory mitigation
efforts may be more successful if the proximate
causes of degradation are identified and
remediated.
Variable 8: Identification of lands not
amenable to compensatory mitigation
Lands not suitable for compensatory mitigation
include rare or threatened habitats such as: old-
growth forests; old fields; habitat used by
federal or state-listed endangered, threatened,
or rare species; or habitat used by unlisted
species but demonstrating a documented
population decline. Uncommon habitat in an
ecologically important landscape should also be
avoided (e.g., upland pine or holly stands
scattered throughout an estuarine marsh which
provide cover or optimal nesting sites). In
addition, habitats which may be common but
provide diverse structure and interactive
ecosystem functions should not be selected as
compensatory mitigation sites (e.g., second-
growth forests contiguous to wetlands in an
urban landscape which provide inter-system
habitat diversity and allochthonous material for
trophic structure support).
Existing or proposed stormwater management
facilities are not generally successful as compen-
satory mitigation sites. For example, highway
interchanges may serve as excellent stormwater
facilities but do not provide optimal habitat,
particularly for wildlife with home ranges
exceeding the acreage within the interchanges.
More appropriate sites to replace the lost
wetlands should be investigated.
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35
GLOSSARY
Advanced Identification (ADID): The process by
which wetlands or other waters of the US. are
identified as either possible future disposal sites or
are generally unsuitable for disposal. See Section
230.80 of the 404(b)(l) Guidelines for additional
information concerning this process.
Chesapeake Bay Executive Council: Signatories to
the Chesapeake Bay Agreement of 1987, composed
of the governors of Maryland, Pennsylvania, and
Virginia, the mayor of the District of Columbia, the
administrator of the VS. Environmental Protection
Agency (for the federal government) and the Chair
of the Chesapeake Bay Commission.
Community: Similar to an ecosystem (see below).
The scale may be smaller and the boundaries
determined individually or in combination using
vegetation composition, hydroperiod, geomorphic
setting, or other factors such as biotic assemblages.
Creation: A type of compensatory mitigation which
involves the establishment of a wetland where one
did not formerly exist. Creation generally takes
place in upland environments.
ulative Impacts: Human activities which
individually may have insignificant adverse effects
but collectively result in significant impacts to
wetland acreage and function; disturbance mecha-
nisms causing adverse spatial or temporal effects to
ecosystems.
Degraded wetland: A wetland which no longer
provides any societal benefits due to the input of
toxic materials or other pollutants that have caused
significant impairment of the wetland ecosystem
function and values.
Disturbed wetland: A wetland with physically
altered structural factors and ecosystem processes
which continues to provide benefits to society.
Effectively drained: Drainage manipulation activi-
ties which completely alter the hydrology of a site
so that it no longer functions as a wetland.
Ecosystem: An area with similar functional, physical,
chemical, and biological forces and interactions
which are self-maintaining. (Adapted from
Gosselink et al. 1990.) As used in this document, a
grouping of wetland communities within a land-
scape.
Enhancement: A type of compensatory mitigation
which involves any activity conducted in an
existing wetland with the goal of manipulating one
or more physical characteristics of the wetland to
increase one or more of the wetland functions.
Exchange: A type of .enhancement which results in
the trading of one wetland type for another.
Fanned Wetland: Wetlands that are seasonally
flooded or ponded (i.e., surface water is present for
at least 15 consecutive days or 10% of the growing
season, whichever ever is less under average
conditions) and have been manipulated prior to
December 23,1985 to produce or with the intent of
producing an agricultural commodity crop, but
otherwise meet wetland criteria.
Federal Action: Any federally funded, permitted,
licensed, or otherwise sponsored activity, regard-
less of project size or potential impact.
Individual Permit: Authorization by the US. Army
Corps of Engineers for specific activities in "waters
of the US." and "navigable waters." Individual
permits may be issued for activities which involve
significant individual or cumulative impacts to
wetlands.
In-kind replacement: Compensatory mitigation
activities which replace the hydrologic core and
structural factors, ecosystem processes, functions,
and values of a project wetland.
Landscape: A spatial mosaic of ecosystems which
interact functionally and are typically measured in
kilometers. Examples are watersheds, physi-
ographic provinces or ecoregions (adapted from
Gosselink et al. 1990).
Mitigation: The sequential process of avoiding,
minimizing, and compensating for impacts to
wetlands and other waters of the United States.
Mitigation Banking: A type of off-site compensatory
mitigation which involves restoration or creation
activities to compensate for future wetland losses
and is established for certain types of activities,
impacts, and wetland types.
Monitoring and Evaluation Program: A formalized
plan which identifies the short and long-term
efforts to oversee the construction, establishment,
and functioning of a wetland mitigation site. The
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36
plan becomes part of an issued federal or state
permit, agreement, or other legal document.
Nationwide Permit: A type of authorization regu-
lated by the US. Army Corps of Engineers for work
in "waters of the U.S." and "navigable waters'*
which does not result in significant individual or
cumulative impacts.
No-net-loss Goal: Goal established in the Chesa-
peake Bay Wetlands Policy which is one temporal
component of the policy to conserve wetland
function and acreage in the short term (no net loss)
and long term (net resource gain). With mitigation,
no net loss is achieved first by avoiding impacts
and secondly by minimizing impacts to wetlands.
Implementing compensatory mitigation for all
remaining unavoidable impacts must then take
place.
Off-site Location: Locating the replicated wetland in
,an area which is not in close proximity to the
altered wetland and which may result in a wetland
that functions differently than the altered one.
On-site Location: Locating the replicated wetland in
an area which is adjacent to the altered wetland
where the ecological functions and societal values
are more likely to be replicated.
Out-of-kind replacement: Creating, restoring, or
enhancing a project wetland with a wetland which
is not structurally and functionally equivalent (or is
not so initially) or with another habitat type which
may not provide wetland structural and functional
equivalency.
Prior-converted cropland: Wetlands that were
drained, dredged, filled, leveled, or otherwise
manipulated (including removing woody vegeta-
tion) before December 23,1985, for the purpose or
to have the effect of producing an agricultural
commodity crop. Prior-converted cropland
includes wetlands which pond or flood for less
than 15 consecutive days during the growing
season and which have been manipulated for
commodity crop production. In addition, the term
includes wetlands which are only saturated by
groundwater and were drained or otherwise
manipulated prior to December 23,1985, and 1)
have been used to produce an agricultural com-
modity crop; 2) have not been abandoned; and 3)
are not currently flooded or ponded for at least 15
consecutive days.
Project Wetland: A wetland which is proposed for
alteration and to which the sequential mitigation
process applies. Synonymous with "altered
wetland."
Restoration: A type of compensatory mitigation
which involves reestablishment of a wetland
through hydrological modification in an area
where the wetland previously existed.
Section 404: Section of the Clean Water Act which
addresses the regulation of activities involving the
disposal of dredged or fill material into a wetland
or other "waters of the US."
Structural and Functional Equivalency: Wetland
replacement activities which are intended to
replicate as closely as possible the structural
factors, ecosystem functions, and societal values of
a wetland.
Unmitigable: Types of wetlands which cannot be
replaced due to their intrinsic value to society.
Defined by the U.S. Fish and Wildlife Service's
Mitigation Policy as "unique and irreplaceable"
habitat.
Wetland: Areas that are inundated or saturated by
surface water or groundwater at a frequency or
duration sufficient to support, and under normal
circumstances do support, vegetation typically
adapted for life in saturated soil (40 CFR Part 232,
Federal Register 53(108): 26764-20787).
Wetland Parcel: A portion of a wetland community
under evaluation for the mitigation process.
Wetland Ecosystem Functions: Groups of ecosystem
processes performed by wetlands.
Wetland Ecosystem Processes: The biogeochemical
interactions operating within wetland ecosystems
which contribute to wetland ecosystem functions
and, ultimately, the values provided by wetland
systems.
Wetland Ecosystem Values: The benefits provided
by wetland ecosystems which are advantageous to
society. Wetland ecosystem values come from the
mechanisms affecting wetland ecosystem processes
and functions, such as hydrology, vegetation
dynamics, and landscape setting.
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37
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Environmental Protection Agency, Philadelphia,
PA. 28pp.
US. Army Corps of Engineers. 1984. Chesapeake Bay
Low Freshwater Inflow Study: Main Report.
Baltimore, MD. 74pp.
US. Army Corps of Engineers and US. Environmental
Protection Agency. 1989. Memorandum of
Agreement Between the Environmental Protection
Agency and the Department of Army Concerning
the Determination of Mitigation Under the Clean
Water Act Section 404(b)(l) Guidelines. Washing-
ton, DC. 6pp.
US. Fish and Wildlife Service. 1980. Habitat Evaluation
Procedures. Ecological Services Manual 102. US.
Fish and Wildlife Service, Washington, DC.
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40
U.S. Fish and Wildlife Service. 1981. U.S. Fish and
Wildlife Service Mitigation Policy. Federal Register
46:7644-7663.
U.S. Fish and Wildlife Service. 1990. Wetland Reserve
Program Summary. Washington D.C. 1 p.
van der Valk, A.G. 1981. Succession in wetlands: A
Gleasonian approach. Ecology 2:688-696.
vanderValk, A.G. 1982. Succession in Temperate
North American Wetlands, pp. 169-179. In:
Wetlands Ecology and Management (B. Gopal, R.E
Turner, R-G. Wetzel and D.F. Whigham, eds.).
National Institute of Ecology and International
Scientific Publications, Jaipur, India.
van der Valk, A.G. and CB. Davis. 1978. The role of
seed banks in the vegetation dynamics of prairie
glacial marshes. Ecology 59322-335.
van der Valk, A.G., R.L. Pederson, and C.B. Davis. 1992.
Restoration and creation of freshwater wetlands
using seed banks. Wetlands Ecology and Management
10:191-197.
Veneman, P.LM. 1986. Science base for freshwater
wetland mitigation in the northeastern United
States: Soils, pp. 115-130. In: Mitigation Freshwater
Wetland Alterations in the Glaciated Northeastern
United States: An Assessment of the Science Base QS.
Larson and C Neill, eds.). Publication No. 87-1,
The Environmental Institute, University of Massa-
chusetts, Amherst, MA.
Wharton, C.H., W.M. Kitchens, EC Pendleton, and
T.W.Sipe. 1982. The Ecology of Bottomland
Hardwood Swamps of the Southeast: A Commu-
nity Profile. FWS/OBS-81/37. US. Fish and
Wildlife Service, Washington, DC. 133 pp.
Whigham, F.F. 1992. Ecological comparisons of a
hydrologically modified flood plain. Abstract
provided at the "Saturated Forested Wetlands of tht
mid-Atlantic Region" workshop, January 29-31,
1992, Annapolis, MD.
White, PS. 1979. Pattern, process and natural distur-
bance in vegetation. Botanical Review 45230-299.
Whittaker, R.H. 1953. A consideration of climax theory:
The climax as a population and pattern. Ecological
Monographs 23:41-78.
Whittaker, R.H. 1967. Gradient analysis of vegetation.
Biological Review 42:207-264.
Wienhold, C.E. and A.G. van der Valk. 1989. The
impact of duration of drainage on the seed banks of
northern prairie wetlands. Canadian Journal of
Botany 67:1878-1884.
Willard, D.E. and A.K. Hitler. 1989. Wetland dynamics:
Considerations for restored and created wetlands.
In: Wetland Creation and Restoration: The status of
the Science. Volume II: Perspectives (J.A. Kuslev
andM.EKentula,eds.). EPA 600/3-89/038b. US.
Environmental Protection Agency, Environmental
Research Laboratory, Corvallis, OR.
Woodhouse,W.W.,Jr. 1979. Building Salt Marshes
along the Coasts of the Continental United States.
Special Report No. 4. U.S. Army Corps of Engineers,
Coastal Engineering Research Center, Ft. Belvoir,
VA. 96pp.
Zimmerman, J.H. 1988. A multi-purpose wetland
characterization procedure, featuring the
hydroperiod. p. 31-54. In: Proceedings of the
National Wetland Symposium: Wetland Hydrology
(J.A. Kusler and G. Brooks, eds.). Association of
State Wetland Managers, Berne, NY.
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SELECTED REFERENCES
uglas, A.J. 1989. Annotated Bibliography of Eco-
nomic Literature on Wetlands. Biological Report
89(19). National Ecology Research Center, US. Fish
and Wildlife Service, Ft. Collins, CO. 67 pp.
Eggers, S.D. 1992. Compensatory Wetland Mitigation:
Some Problems and Suggestions for Corrective
Measures. US. Army, Corps of Engineers, St. Paul
District, St. Paul, Minnesota.
Hamilton, P.A., RJ. Shedlock, and P.J. Phillips. 1989.
Ground-water-quality Assessment of the Delmarva
Peninsula, Delaware, Maryland, and Virginia —
Analysis of Available Water-quality Data through
1987. Open-File Report 89-34. US Geological
Survey, Denver, CO.
Kusler, J.A., M.L Quammen, and G. Brooks, eds. 1988.
Proceedings of the National Wetland Symposium:
Mitigation of Impacts and Losses. ASWM Technical
Report 3. Association of State Wetland Managers,
Berne, NY. 459pp.
Marble, A.D. 1992. A Guide to Wetland Functional Design.
Lewis Publishers, Boca Raton, FL. 222 pp.
Larson, J.S.,ed. 1973. A Guide to Important Character-
~" istics and Values of Freshwater Wetlands in the
Northeast. Models for Assessment of Freshwater
Wetlands. Publication No. 31 (Reprint). Water
Resources Research Center, University of Massa-
chusetts, Amherst, MA. 91 pp.
Sather,J.H. and R.D. Smith. 1984. An Overview of
Major Wetland Functions and Values. FWS/OBS-
84/18. U.S. Fish and Wildlife Service, Washington,
D.C. 68pp.
. Environmental Protection Agency. 1984. Literature
Review of Wetland Evaluation Methodologies.
Technical Report. US. Environmental Protection
Agency, Region V, Chicago, IL. 120 pp. plus
Appendices.
US. Soil Conservation Service. 1992. Chapter 13,
Wetland Restoration, Enhancement, or Creation.
Engineering Field Handbook, Part 650. U.S.D.A., US.
Soil Conservation Service, Washington, D.C. 79pp.
Wolf, R.B.,LC. Lee, and R.R.Sharitz. 1986. Wetland
creation and restoration in the United States from
1970 to 1985: An annotated bibliography. Wetlands
6:1-88.
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*
APPENDIX A
FEDERAL LEGISLATION OR RELATED PROGRAMS
AFFECTING CHESAPEAKE BAY WETLANDS
A. Emergency Wetlands Resources Act of 1986
The Emergency Wetlands Resources Act was enacted by Congress in 1986
to:
"... promote, in concert with other Federal and state statutes and pro-
grams the conservation of wetlands of the Nation in order to main-
tain the public benefits they provide and to help fulfill international
obligations contained in various migratory bird treaties and conven-
tions with Canada, Mexico, Japan, the Union of Soviet Socialist
Republics and with various countries in the Western Hemisphere by-
(1) intensifying cooperative efforts among private interests and local,
state and Federal governments for the management and conservation
of wetlands; and
(2) intensifying efforts to protect the wetlands of the Nation through
acquisition in fee, easements or other interests and methods by local,
state and Federal governments and the private sector."
Section 301 of the act requires the establishment of a National Wetlands
Priority Conservation plan. This plan specifies regional wetland types and
interests which should be given priority acquisition by federal and state
agencies. In 1990, the US. Fish and Wildlife Service, Northeast Region
published a "Regional Wetlands Concept Plan" (i.e., Regional Plan) to
complement the National Plan. The Regional Plan identifies 850 privately-
owned wetlands in 13 northeastern and mid-Atlantic states. Most of these
sites meet the criteria for acquisition as outlined in the act. In addition,
these sites may be proposed as "Wetlands Conservation Projects" for
acquisition, easement, enhancement, or restoration pursuant to the North
American Wetlands Conservation Act
6. North American Waterfowl Management Plan and the Atlantic
Coast Joint Venture
In May 1986, the U.S. and Canada signed the "North American Waterfowl
Management Plan" which provides a framework for the conservation and
management of waterfowl. It addresses actions both countries must
undertake to reverse declining waterfowl populations. Chief among the
principles of the plan is the protection, enhancement, and management of
wetlands as important waterfowl habitat. Specifically, the thrust of this
continental effort is to protect habitat for 62 million breeding ducks, over
100 million migratory birds. In addition, habitat protection is needed to
support more than 6 million over-wintering geese. To achieve these goals,
the plan recommends establishment of "joint ventures." Joint ventures are
cooperative efforts between government and private organizations to both
finance priority research and plan, fund, and implement management
projects to benefit waterfowl.
The plan identified five geographic areas where the problem of habitat loss
is in need of immediate attention to increase waterfowl populations. These
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areas are termed "priority areas." Priority areas are historically important
waterfowl breeding and wintering habitats where significant habitat degra-
dation has occurred. The mid and northern Atlantic Coast were jointly
identified as one priority area. This priority area is historically significant as
migration and wintering habitat for black ducks (Anas rubripes).
To address the black duck population decline in the Atlantic Coast priority
areas the "Atlantic Coast Joint Venture Plan" (ACJV Plan) was developed.
As stated in the ACJV (p.ll) the goal of this cooperative government-private
effort is to:
"Protect and manage priority wetland habitats for migration, wintering,
and production of waterfowl with special consideration to black ducks, and
to benefit other wildlife in the joint venture areas."
To meet the ACJV Plan goal, the following two objectives were developed:
1. To protect, manage, and enhance consistent with the goal, 879,128
acres... of wetland and upland buffer habitats within the joint venture
area over the next 15 years.
2. To improve and enhance an additional 165,977 acres... of federal and
state wetland habitats currently managed for waterfowl to maximize
carrying capacity for waterfowl and other wildlife.
The ACJV Plan summarizes several strategies to achieve the above objec-
tives, including:
"Review migratory legislation and enforcement: Evaluate existing
wetland protection legislation and work with ongoing programs to
strengthen or improve existing federal-state wetland protection efforts
and to facilitate wetland management activities...."
"Wetland restoration; Implement measures to restore natural vegeta-
tion and improve the health and productivity of wetland habitats that
have deteriorated due to hiliman impact —"
"Watershed protection and management; Degradation of wetland
health and productivity by municipal waster, agricultural runoff,
sedimentation, and industrial contaminants needs to be eliminated by
developing guidelines and providing input to watershed management
plans."
"Mitigation: Work with federal and state regulatory agencies to ensure
mitigation policies and mitigation actions resulting from development
projects enhance wetland management opportunities."
The ACJV Plan identifies several wintering, migration and breeding areas
important to black ducks as well as other waterfowl, shore and wading
birds, raptors, anadromous fish, and other fish and wildlife species. These
lands are termed "focus areas". Appendix E lists the ACJV Plan focus areas
along with acreage and characterization as "protection"1 or "enhancement"2
1 Protection measures refer to acquisition, easement agreements, leases or donations.
2 Enhancement activities, such as open water marsh management noxious weed control, and
impoundment improvement are intended to improve an area's capacility to support waterfowl
and other fish and wildlife.
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C. North American Wetlands Conservation Act
The North American Wetlands Conservation Act was enacted to:
"... conserve North America's wetland ecosystems and waterfowl and
the other migratory birds and fish and wildlife that depend upon
such habitats."
The Act recognizes the importance of wetlands in the "maintenance of
healthy populations of migratory birds "throughout North America. As
such, its purposes are:
(1) "... to protect, enhance, restore, and manage appropriate distribu-
tion and diversity of wetland ecosystems and other habitats for
migratory birds and other fish and wildlife in North America;
(2) to maintain current or improved distributions of migratory bird
populations; and
(3) to sustain an abundance of waterfowl and other migratory birds
consistent with the goals of the North American Waterfowl
Management Plan and the international obligations contained in
the migratory bird treaties and conventions and other agreements
with Canada, Mexico, and other countries."
A key feature of this legislation is to recommend "Wetlands Conserva-
tion Projects." The projects must meet the purposes of the Act, the
North American Waterfowl Management Plan, or the Tripartite Agree-
ment of 1988 between the U.S., Canada, and Mexico, for funding pur-
poses. Wetlands Conservation Projects can take the form of acquisition,
easement, management, restoration, or enhancement of wetlands, and
must be conducted for the "long-term conservation of wetlands and fish
and wildlife." "Long-term conservation" is interpreted to mean3 projects
which reserve habitat in perpetuity. The establishment of easements to
conserve wetlands for 25 years of more is also viewed as a long term
conservation project, although less desirable than perpetual easements.
Short-term easements (i.e., less than 25 years) may be appropriate
when the landowner is likely to agree to a longer term conservation
agreement when the short-term agreement expires.
Wetland Conservation Projects which involve enhancement are defined
as those which result in "the modification of a wetland ecosystem to
improve its value for migratory birds and other fish and wildlife."
Wetland Conservation Projects involving restoration are those which
rehabilitate "a naturally occurring but degraded wetland ecosystem."
Implementation of federally-funded conservation projects is not in-
tended to imply blanket approval of such projects pursuant to Section
404 authorization, or any other federal or state wetland laws, regula-
tions, or requirements.4 In addition, the act is not intended to support
the alteration of existing viable wetlands to achieve single-purpose
benefits at the expense of the variety of benefits provided by existing
functioning wetlands. This it particularly relevant with respect to
'Information contained in the Senate Committee on Environment and Public Works report 1101-
161, October 15,1989, on the North American Wetlands Conservation Act.
'Ibid
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waterfowl production.5 Conversely, degraded habitats are considered
prime candidates for restoration (e.g., former disposal sites vegetated with •
Phragmites communis.
D. The Food Security Act of 1985 and the Food, Agriculture,
Conservation, and Trade Act of 1990
The Food Security Act (1985 Farm Bill) dramatically changed the public
approach to wetland conservation. For the first time, receipt of most
federal farm program benefits - including commodity price supports,
agricultural credit, and crop insurance - became contingent on the applica-
tion of land stewardship practices by agricultural producers, including the
protection of wetlands. Partially in response to the 1985 Farm Bill, the
protection, restoration and management of wetlands has become an impor-
tant USDA priority.
The main provisions of the Conservation Title of the 1985 Farm Bill were:
the Conservation Reserve Program, Swampbuster, Sodbuster, and Conser-
vation Compliance. The 1990 Farm Bill added the Wetland Reserve
Program to these previously authorized provisions.
Swampbuster Provisions:
Basically, Swampbuster includes provisions designed to discourage the
draining of wetlands for agriculture. Under the 1985 Farm Bill, a wetland
could be converted only if an agricultural commodity crop was not planted.
In addition, the penalty for a violation was complete denial of all federal
farm program benefits regardless of the size of the violation.
The 1990 Farm Bill strengthened Swampbuster by stipulating that viola-
tions include the act of draining or manipulating a wetland to make plant-
ing an agricultural commodity crop possible. The 1990 Farm Bill also
instituted a system of graduated fines that ranged from $750 to $10,000,
depending on the severity of the violation.
Wetland Reserve Program Provisions of the 1990 Farm Bill:
The 1990 Farm Bill contains provisions which require the U.S. Department
of Agriculture "to implement a voluntary wetland easement program to
assist owners of reliable lands in restoring and protecting wetlands." Lands
eligible for enrollment in the Wetland Reserve Program include the follow-
ing:
"Farmed and converted wetlands, excluding those that were not
commenced prior to December 23,1985, where the wetland value and
the likelihood of successful restoration merit inclusion, taking costs
into consideration."
"Functionally dependent adjacent lands (to be kept to a minimum)."
"Other associated wetlands, if they would significantly add to the
value of an easement (to be kept to a minimum)."
"Riparian corridors that link protected wetlands."
"Fanned and prior-convened wetlands which are presently enrolled in
the Conservation Reserve Program."
Mbid.
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Landowners willing to enroll lands under a permanent easement which
protect and enhance migratory bird and other wildlife habitat are given
priority over those whose lands which may be enrolled at the minimum 30-
year time period for this program.
Landowners are required to record the easements on the land deed, imple-
ment the wetland restoration and protection plan, provide an access route
for easement management, and preclude activities on adjacent lands that
decrease wetland benefits.
Easement plans will include details regarding restoration management and
other applicable measures, identify permitted uses (e.g., periodic haying,
grazing, or fishing) and the conditions of such uses, and other relevant
information to provide for the restoration and maintenance of wetland
functions and values.
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'APPENDIX B
APPLICABILITY OF SELECTED FEDERAL WETLANDS
LEGISLATION
AND PROGRAMS TO THE MITIGATION TECHNICAL GUIDANCE
FOR CHESAPEAKE BAY DOCUMENT
The goals of the Chesapeake Bay Wetlands Policy are supported by the
requirements of the Emergency Wetlands Resources Act, the North Ameri-
can Waterfowl Management Plan and Atlantic Coast Joint Venture, North
American Wetlands Conservation Act, and the Wetlands Reserve Provi-
sions of the 1990 Farm Bill.
In the wetlands regulatory arena, applications may be submitted for work
in wetlands listed in the Regional Wetlands Concept Plan. These plans
provide wetland values information used to determine if the site has
received special recognition by a federal or state agency.
The values information for the Regional Wetlands Concept Plan sites
should supplement information gathered from other sources. It should not
substitute for site reconnaissance or quantitative function or values infor-
mation.
Many of these sites are viewed by various federal and state natural resource
agencies as viably functioning wetlands which provide important public
benefits. As such, efforts to avoid impacts which would result in diminu-
tion of public benefits should be exhausted.
Where the sites comprise significant or critical portions of a watershed (e.g.,
Patuxent River marshes, Chickahominy River swamp), landscape-level
planning efforts are necessary to ensure that neither physical or functional
fragmentation of the wetland system will occur as a result of numerous
disjunct human activities.
Many prior converted wetlands1 on the Delmarva peninsula are prime
candidates for restoration activities. Where the hydrology has been altered
so that the area is "effectively drained"2, restoration activities can reestab-
lish wetland hydrology, vegetation, and at least periodically, reduced soil
conditions. Many of the areas could be managed for waterfowl, wading
birds, shorebirds, and other wildlife with little manipulation of existing site
conditions (e.g., removal of tile drainage structures, plugging existing
drainage ditches). Additionally, where conditions are feasible, terrestrial
habitat restoration is encouraged, particularly where such restoration
results in a naturally vegetated buffer adjacent to the wetland site. When
possible, acquisition of these lands by conservation organizations, land
trusts, educational institutions, or other nongovernment organizations is
encouraged to protect them in perpetuity. When acquisition is not feasible,
1 "Prior-converted croplands" are defined in the Food Security Act Manual as "...wetlands that were
drained, dredged, filled, leveled or otherwise manipulated before December 23, 1985 for the
purpose, or to have the effect of, making the production of an agricultural commodity possible.
This applies if (i) such production was not possible before the action, (ii) an agricultural commodity
has been produced (planted) at least once, and (iii) the area has not been abandoned.
2 Regulatory Guidance Letter No. 90-7, September 26, 1990.
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easements, agreement, or leases between government agencies or conserva-
tion organizations (e.g., Ducks Unlimited, The Nature Conservancy, local
land trusts) and the landowners should be sought.
Restoration of prior-converted croplands would help meet one of the
objectives of the Atlantic Coast Joint Venture Plan:
To protect, manage, and enhance, consistent with the goal, 879,138
acres... of wetland and upland buffer habitats within the joint venture
area over the next 15 years.
Both the North American Waterfowl Management Plan and the Atlantic
Coast Joint Venture Plan recognize that project implementations must
consider other wildlife and wetland values. As such, the following guide-
lines, in addition to those listed above, should be followed in the design of
restoration and enhancement plans on prior-converted wetlands:
• The basic ecological principals and guidance provided in this hand-
book should be followed.
• Federal and state natural resource agencies and conservation organiza-
tions are encouraged to develop a "Prior-converted Wetland Restora-
tion Plan." The plan should complement the Atlantic Coast Joint
Venture focus area plans and satisfy the purpose of the North Ameri-
can Wetlands Conservation Act (i.e., restoration activities should not
solely address waterfowl). The plan should also identify lands with
willing sellers and lands that could be managed cooperatively via
easements, agreement, or leases. Prior-converted wetlands adjacent to
existing state or federal lands should also be identified. Where pos-
sible, the target lands should connect or lie adjacent to other wetlands
which are protected.
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»
APPENDIX C
TECHNICAL SUMMARY OF
WETLAND ECOSYSTEM PROCESSES
Organic Matter Production
Organic matter production generally refers to the ability of plants, prima-
rily macrophytes, and various algae to fix carbon during photosynthesis to
produce an organic energy source usable by heterotrophs (Adamus and
Stockwell 1983; Larcher 1983). In tidal wetland systems, phytoplankton
also serve as an important organic energy source for heterotrophic organ-
isms (Odum 1984). Nitrogen-fixing prokaryotes (cyanophytes and bacteria,
such as the actinomycete Frankia) are able to fix atmospheric nitrogen (i.e.,
dinitrogen - N2) which is incorporated into carbon compounds to form
amino acids. The amino acids are synthesized to produce proteins, nucleic
acids and other nitrogen compounds for plant growth and maintenance
(Larcher 1983). In general, organic matter production in wetlands is
dominated by vascular plants (Moran et al. 1988).
Organic matter production in wetlands (or other community types) is
measured as "primary productivity" - the rate at which biomass is pro-
duced by plants per unit area . The total rate at which carbon is fixed via
photosynthesis is "gross primary production" (GPP). Gross primary
production minus community respiration equals "net primary productiv-
ity" (NPP) (Barbour et al. 1987). Estimates of net primary production are
but one indicator of a wetland's viability, however and should not consti-
tute the only variable to determine the inherent "value" of a wetland
(Brinson et al. 1981). For example, an ombrotrophic peatland typically has
a lower NPP than does a riparian wetland, but both systems contribute to
the regional landscape productivity (Brinson et al. 1981). In addition, such
peatlands, because of their extreme physical conditions, are typically
inhabited by endangered, threatened, and rare species, particularly plants.
As discussed more fully below, organic matter production together with
decomposition, energy flow, and nutrient cycling and transformation
processes support complex and diverse food webs. The trophic levels
dependent upon these wetland functions exist beyond the physical wetland
boundary, involving a variety of downstream and adjacent aquatic and
terrestrial fish and wildlife species.
Organic Matter Decomposition
Much of the fixed carbon in live plant material is unavailable as an energy
source and requires further biological and chemical breakdown to become
assimilated by other organisms. While herbivory (i.e., feeding upon live
plant material by herbivores and omnivores) does constitute an important
component of wetland food webs, decomposing plant tissue provides the
substrate upon which the majority of wetland trophic structures exist.
Decomposing plant matter is known as "detritus." Detritus can take
several forms: coarse particulate organic matter (CPOM), such as leaves
and twigs which are >1 mm; fine particulate organic matter (FPOM), leaves
and twigs which have been processed to particle sizes <1 mm; and dis-
solved organic matter (DOM), particles in solution which are <0.5 microns
(Wharton et al. 1982). The particulate organic matter (POM) is first pro-
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50
cessed by microorganisms such as fungi, with further particle size reduc-
tion occurring by "shredders" such as amphipods.
The production of detritus is controlled by a variety of physical factors
including temperature, oxygen, and water (Mitsch and Gosselink 1986).
High temperatures enhance rates of decomposition. In addition, fluctuat-
ing water and oxygen levels, such as those occurring in regularly flooded
tidal wetlands or nontidal wetlands with alternating wet/dry periods,
provide optimum physical conditions for increased rates of decomposition
in many wetland systems.
Biological factors also affect vegetation decomposition. The plant tissue
nutrient composition and physical structure (e.g., high nitrogen content,
low lignin content) are very important in determining the rate of decompo-
sition as well as the types of microorganisms responsible for the initial
decomposition process.
Energy Flow
Once organic carbon is produced and available via plants, various path-
ways exist to distribute the food energy. Depending upon the wetland
type, detrital or grazing food chains may predominate (Odum 1971). Many
wetlands have both detrital and grazing food chain linkages, resulting in
complex trophic interactions.
Detrital pathways involve numerous trophic levels, and the transportation
of organic materials. The concept of detrital food webs in wetlands begins
with the colonization of decomposing plant material by microorganisms,
such as protozoa, bacteria and fungi. These in turn are fed upon by
meiobenthic detritivores (e.g., nematodes), which further process the
material for consumption by macroinvertebrates, such as filter-feeders and
deposit-feeders. Some organisms directly ingest the organic material (e.g.,
crayfish). Macroinvertebrates may also ingest meiobenthic detritivores.
Detritivores include springtails, mites, isopods, annelids, and crayfish in
forested wetlands (Wharton et al. 1982; Brinson et al. 1981); chironomids
(larvae) and amphipods in tidal freshwater wetlands (Odum 1984); and
isopods, turbellarians, gastrotrichs and ostracods in salt marshes (Mitsch
and Gosselink 1986; Gosselink 1984). Vertebrate species within, adjacent, or
downstream of a wetland feed upon detritivores, macrobenthics, and other
vertebrate species. For example, crayfish which ingest detritus as well as
other detritivores are fed upon by raccoons, wading birds, and humans.
In addition, diatoms and other algae may colonize the decomposing plant
litter, enriching it as a food source for "scrapers" such as snails and other
grazers. Wading and shore birds feed upon the grazers. The particulate
matter ingested, processed and excreted also becomes FPOM, a source of
energy for deposit feeders (Mitsch and Gosselink 1986; Wharton et al. 1982).
Dissolved organic matter (DOM), particularly dissolved organic carbon, can
also be utilized by various organisms directly. Under appropriate condi-
tions, DOM may form aggregates of FPOM through physical flocculation
(Wharton et al. 1982; Cummins 1974). The FPOM is then filtered from
suspension by filter-feeders (McArthur 1989) or ingested by deposit feeders
as a component of the particulate detrital pathway.
Grazing food chains involve direct feeding upon live plant material by
herbivores and omnivores, termed "herbivory" (Odum 1971). Herbivory
may be an important pathway for converting fixed carbon in plants to
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energy for certain heterotrophs. Muskrat, Canada goose, beaver, deer,
marsh rabbit, several passerine bird species, and insects ingest live wetland
vegetation, including fruits, twigs, shoots, leaves, and tubers (Mitsch and
Gosselink 1986; Wharton et al. 1982). Such herbivores also contribute to
the detrital pathway via excrement deposited in the wetland and subse-
quent colonization of this excrement by decomposers.
Biogeochemical Cycling and Transformation
Studies of nutrient dynamics in wetlands are often intended to characterize
the wetland as a nutrient "source," "sink," or "transformer" (Mitsch and
Gosselink 1986). Nutrient studies may show that a wetland serves as a sink
for any particular element if there is a net retention of that element (or a
specific form of that element). If a wetland exports more of an element to
downstream or adjacent systems than would be exported if the wetland
were absent then the wetland is characterized as an exporter. If the amount
imported and exported for any element (or its specific form) remains the
same (but the chemical form is changed), the wetland is termed a trans-
former (Mitsch and Gosselink 1986). There is little agreement in the
literature on whether wetlands are sources, sinks, or transformers of
various nutrients. Wetlands do serve as sinks for certain inorganic nutri-
ents, export organic materials to downstream and adjacent systems, or
transform inorganic inputs to organic forms for export (Mitsch and
Gosselink 1986).
At the soil-water interface of wetlands, a thin layer of oxidized soil exists.
It is this layer which is important in wetland nutrient cycling and chemical
transformations (Mitsch and Gosselink 1986). The lower anaerobic soil
layers are characterized by reduced forms of nitrogen, sulfur, iron, and
manganese. The oxidized ions of these elements occur at the soil surface.
Phosphorus is not directly altered by spatial or temporal redox potential
fluctuations, but is affected by those elements which do fluctuate (Mitsch
and Gosselink 1986).
Nitrogen transformations involve the following processes: mineralization,
nitrification, nitrate reduction, denitrification, fixation, and ammonia
volatilization (Bowden 1986; Mitsch and Gosselink 1986; Brinson et al.
1981). Both biological and chemical activities are responsible for the
cycling of nitrogen in wetlands via these transformation processes.
Sulfur is rarely limiting in wetland systems, but in reduced form (i.e.,
sulfides) can be highly toxic to both microbes and rooted emergents
(Mitsch and Gosselink 1986). The familiar smell of rotten eggs in salt
marshes is reduced hydrogen sulfide. In wetland soils with high ferrous
iron (Fe**) concentrations, the sulfur binds with the iron to form insoluble
sulfides which can be less toxic than hydrogen sulfide. The black color
characteristic of many wetland soils is due to the presence of ferrous
sulfide (Mitsch and Gosselink 1986). Oxidation of sulfides to elemental
sulfur and sulfates is accomplished by chemoautotrophic and photosyn-
thetic microorganisms in wetland soil aerobic zones (Mitsch and Gosselink
1986).
Reduced forms of manganese (Mn**) and iron (Fe**) are characteristically
present in wetland soils. These forms are soluble and therefore more
obtainable by organisms (Mitsch and Gosselink 1986). The presence of Fe**
in wetland soils results in a bluish-green color characteristic of reduced soil
conditions.
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Phosphorus occurs in soluble and insoluble inorganic and organic forms in
wetland soils (Mitsch and Gosselink 1986). The soluble inorganic forms,
orthophosphates, are biologically available. The insoluble inorganic and
organic forms and the soluble organic forms of phosphorus must undergo
transformation processes before rendering them available for biological
uptake (Mitsch and Gosselink 1986). Much of the literature for freshwater
marshes, forested wetlands, and salt marshes suggests that phosphorus is
retained within a wetland, with much of it found within the soil (Mitsch
and Gosselink 1986), characterizing such wetlands as phosphorus "sinks."
Odum et al. (1984), however, hypothesized that tidal freshwater systems
transform inorganic oxidized forms of phosphorus via microbial activity to
organic forms with a net export of the organic phosphorus to tidal waters
for further biological processing and uptake. Decaying plant litter serves as
a site for long-term or seasonal immobilization of phosphorus by microbes
in both tidal (Odum et al. 1984) and nontidal wetland systems (Brinson
1977; Day 1982; Odum et al. 1982).
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APPENDIX D
ATLANTIC COAST
JOINT VENTURE FOCUS AREAS
Pennsylvania
The Atlantic Coast Joint Venture encompasses the eastern one-third of
Pennsylvania. Within this boundary are eight focus areas.
Southeastern Area
The Southeastern Area is in the Delaware River and Susquehanna River
drainage systems, The lower part of the Susquehanna is just above the
Chesapeake Bay. The Delaware River empties into the Delaware Bay. The
lower part of the Delaware River in Pennsylvania is tidal freshwater and
has accompanying marshes.
This area is a non-glaciated section of Pennsylvania. The major forest type
is oak-hickory. .The area has fertile soils (Alfisols, Ultisols, and Inceptisols)
and much of it is underlain with limestone. The land-use regime in this
area is cropland (60%), forest (25%), urban (10%), and idle and wetlands
(5%). Beaver are scattered throughout this area in limited numbers, espe-
cially in the northern part and along the Susquehanna and Delaware Rivers.
Waterfowl use the Southeastern Area in all seasons - breeding, migrating,
and wintering. Mallards, wood ducks, Canada geese, and black ducks are
the principle breeding waterfowl, in that order. Limited numbers of other
dabblers, especially teal, also nest here. Forty years ago, black ducks and
wood ducks were the most common breeders; now it is mallards and
Canada geese. During migrations, spring and fall, tens of thousands of
waterfowl move through the Southeastern Area, many stopping. It is
common to have 50,000-100,000 ducks and 100,000-150,000 Canada geese on
the ground during migration. While black ducks and mallards are the most
plentiful ducks migrating, most species of dabbling and diving ducks and
mergansers are present, some in good numbers. Also, thousands of whis-
tling swans stop during their travels. Some may stay as long as a month
during spring migration. During the late fall migration and into winter,
there often are as many and sometimes more, black ducks in the area as
there are mallards. Depending upon icing conditions, tens of thousands of
waterfowl, again chiefly mallards, black ducks, and Canada geese are
present; often many divers (e.g., canvasbacks, goldeneyes) and mergansers
are present.
Many other birds (waterbirds, shorebirds, rails, snipe, birds of prey, ruffed
grouse, wild turkey, and songbirds) use this area throughout the year.
Native species abound in the area: cottontail rabbits, squirrels, goundhogs,
deer, and furbearers. Muskrats, ring-necked pheasants, and bob-white
quail are present, but their abundance is limited by habitat factors.
Four focus areas have been identified of which the Susquehanna River is
the top priority.
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1. Susquehanna River Lowlands (Lancaster, Dauplin, York, and
Chester Counties) '
This focus area includes the Susquehanna River from Sunbury to the
Maryland state line and adjacent and nearby lands, including the
Octararo Reservoir and Muddy Run Reservoir. This whole complex
will be referred to as the Susquehanna River Lowlands (SRL). There is
a good waterfowl marsh on Department of Defense land at New
Cumberland.
The SRL is an important staging, migrating, and wintering area for
large numbers of waterfowl A good number of ducks (i.e., mallards,
wood ducks, and black ducks) and Canada geese also breed here and
on adjacent lands. Thousands of Canada geese, ducks, and whistling
swans rest and feed on the SRL and in nearby fields during spring and
fall migrations. The SRL is heavily used by black ducks and canvas-
backs. SRL is becoming an important area for migrating and wintering
bald eagles and osprey. In 1988, a bald eagle nested on the lower
reaches of the Susquehanna River. Herons and egrets nest on the river
islands. Yellow-crowned night herons nest here, the only known site in
the state. Other waterbirds and shorebirds migrate through here.
Upland sandpipers used to nest and many still nest in nearby fields.
Many small marshes and wetlands, bottomland hardwoods, idle land,
agricultural land, islands, and old canal beds need to be secured in the
SRL. A main threat is human development and degradation of this
environment Unwise use of the floodplain continues.
Several state management areas exist in this area and many opportuni-
ties exist to enhance the quality of these areas via water control struc-
tures, diking, and small impoundments. Being a major waterfowl
migration, wintering (until freeze up), and breeding (some) area, a
major management effort within the SRL can add to the numbers of
waterfowl using it, especially black ducks. Proper management can
also add to the well-being of waterfowl, especially by sending them
back to the breeding grounds in good condition. Approximately 8,300
acres have been identified for protection and 2,500 acres for enhance-
ment with this focus area.
2. Middle Creek Wildlife Management Area Ontelaunee Reservoir
• Corridor (Lebanon, Lancaster, and Berks Counties)
This area is comprised of fertile farmland, low-lying fields, and numer-
ous wet areas. Current public lands - Middle Creek WMA (Pennsylva-
nia Game Commission), Blue Marsh Lake (COE), and Ontelaunee
Reservoir (Reading Water Co.) - currently have large numbers of ducks
and Canada geese. During migration, numbers may peak at 30,000-
50,000 geese and 10,000-15,000 ducks. Mallards, wood ducks, and
black ducks are the common species, but reasonable numbers of other
species also occur. These four species also nest in the area in good
numbers. Many shorebirds, waterbirds, birds of prey (including
osprey and eagles), and songbirds migrate through. Threatened bog
turtle populations occur on Middle Creek. The area also contains good
habitat for muskrats, bobwhite quail, and ring-necked pheasants, all of
which are at low levels.
This land needs to be protected, not only for wildlife, but for water
table maintenance and watershed flood control It is continually under
threat of development, degradation, and pollution. An additional
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minimum 2,000 acres needs to be protected. Approximately one-fourth
of this amount should be enhanced.
3. Marsh Creek (Chester County)
The large marsh (perhaps the largest marsh in the Southeast Area),
adjacent Marsh Creek State Park, and surrounding area are extremely
important to waterfowl. Excessive encroachment, pollution, and habitat
degradation by people threaten the rich environment of this area.
Several thousand Canada geese and hundreds of ducks (many black
ducks and mallards) use this area for migration and wintering (when
ice-free). Many waterfowl also breed here.
A minimum of 1,500 acres needs to be protected via acquisition, lease, or
cooperative agreement on marsh and adjacent upland and 300 acres
enhanced.
4. Bucks and Montgomery County Wetlands
These two counties have a number of county parks with reservoirs that
harbor tens of thousands of Canada geese and thousands of ducks
(many black ducks and mallards) during migration and often through
winter. A number of these waterfowl interact with New Jersey, Dela-
ware, and Maryland. Many waterfowl breed here, especially wood
ducks, and their habitat desperately needs protection. For example, in
Bucks County, the 1987 Christmas Bird Count noted 35,000 geese. There
are a number of small wetlands associated with these reservoirs and also
scattered throughout the county and attractive adjacent uplands. These
areas need protection from rapidly expanding human development,
pollution, flood problems, water regime deficit, and habitat degradation.
These areas are especially attractive to shorebirds and birds of prey.
There is also limited nesting of Virginia and sora rails.
Approximately 1,500 acres need to be protected via acquisition, lease, or
cooperative agreements. Enhancement activities could include im-
poundments, nest boxes, predator and people control, sharecropping,
and information/education with local landowners. Much of this work
would be done in cooperation with the counties, electric companies, and
watershed groups.
Northeastern Area
The Northeastern Area is also in the Susquehanna and Delaware River
drainage systems. This area is experiencing a booming local economy fueled
by second home development, recreational/resort development (e.g. ski
areas), and peat mining. Approximately 80-90% of this focus area is forested.
While wetlands are generally small in size in this area, they are numerous. A
number of formerly productive waterfowl marshes have been converted to
recreational ponds. This area is the best black duck breeding area in the
state. In some locations, black ducks outnumber mallards. Overall, mallards
outnumber black ducks in a 6535 proportion. Wood ducks also are plentiful
and breed in this area in numbers that are at least equal to those of mallards.
A pilot breeding pair survey was conducted on sample plots in this area in
1988. The results suggested good numbers of breeding pairs of wood ducks,
mallards, and black ducks. Green-winged teal and hooded mergansers breed
in limited numbers. Local breeding Canada geese populations also are
increasing. Due to a successful hacking program, ospreys now breed in this
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area. American bittern (state-threatened species), Virginia rail, great blue
heron, and green-backed heron are some of the water birds that breed in
the area. These water birds, plus other shorebirds, ospreys, eagles, and
hawks migrate through the area. Otter, beaver, and black bear are frequent.
5. Tobyhanna-Gouldsboro Project (Wayne, Monroe, and Lackawanna
Counties)
This high-priority focus area is divided into two tracts - the northern
tract (primarily Silkman's Swamp) is all private land. The southern
tract is 3/4 private land with the remainder included in Tobyhanna
State Park and Tobyhanna Army Depot (just south of the State Park).
State Game Lands #127 (Game Commission owned) adjoins the State
Park on the southwest edge of the park.
The habitat is mostly forested with non-wooded marshes, timbered
wetlands, beaver dams, and streams. This area is most valuable for
waterfowl breeding, especially for black ducks and wood ducks.
Mallards, green-winged teal, and hooded mergansers also breed here.
Preservation and enhancement of this habitat will also benefit water-
birds, rails, and snipe. Other important wildlife in the area include
otter, bear, muskrat, beaver, osprey, other birds of prey (especially red-
shouldered hawks), and songbirds associated with wetlands. Approxi-
mately 26,666 acres have been identified for protection primarily via
acquisition, easement, and cooperative agreements. Enhancement
measures are needed on 5,200 acres of private, state park, and Army
Depot lands.
6. State Game Lands #13,57, and 66 (Wyoming, Sullivan, and Luzerne
Counties)
The habitat in this focus area is approximately 75% forested; the
remainder are open lands (farmland, reverting land) and marshes.
Beaver dams occur in forested and non-forested areas. The land is
about equally divided among private ownership and public (State
Game Lands).
This focus area has more value for breeding than for migrating water-
fowl. The area (totaling 94,000 acres of State Game Lands) is an
important core for breeding black ducks and wood ducks. Acquisition
of adjacent wetlands and enhancement of State Game Lands wetlands
could make this a much more significant area for waterfowl. Protec-
tion and enhancement of this whole area could contribute significantly
to populations of otter, muskrats, rails, bittern, other waterbirds and
waterfowl, red-shouldered hawks, osprey, bald eagles, and other
wildlife associated with quality wetlands. An additional 3,000 acres are
identified for protection, primarily via acquisition, and 15,000 acres are
in need of enhancement
7. State Game Lands #180 (Pike County)
The focus area consists of State Game Lands #180 (12,000 acres) and
approximately 12,000 acres of private land and public land surround-
ing State Game Lands 180. The habitat is approximately 80% forested.
The remainder is grasslands, reverting land, and non-wooded marshes.
Beaver impoundments occur in forested and non-forested areas. The
public land includes Pecks Pond, Promised Land State Park, and the
Delaware State Forest.
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This State Game Lands once attracted many waterfowl for breeding
and during migration. Waterfowl usage has decreased over the years
due to uncontrolled public use and deteriorating waterfowl habitat.
An uncontrollable factor that also may have affected waterfowl usage
is the second home/recreational development around and on other
wetlands in the vicinity of State Game Lands #180. Acquisition/public
use control of key wetlands near State Game Lands #180 and enhance-
ment of wetlands on the State Game Lands could significantly im-
prove waterfowl production in this project area. Aquatic mammals,
waterbirds, and birds of prey would certainly benefit. This State Game
Lands also is an eagle hacking site. Three thousand acres heed to be
protected and 5,000 acres enhanced.
8. Wayne County
This focus area is the remainder of Wayne County, not included in the
Tobyhanna-Gouldsboro project There are many wetlands, including
beaver impoundments, along with a good breeding waterfowl popula-
tion (wood ducks, black ducks, mallards). Approximately 40% of
Wayne County is forested (with forested wetland areas and impound-
ments). The remaining area is farmland, reverting land, and wetlands.
State Game Lands acreage in Wayne County totals 16,600 acres.
With the many wetlands in Wayne County, it is primarily important as
a waterfowl production area. Migrants, waterfowl and songbirds,
aquatic mammals, birds of prey, and other water birds also are impor-
tant fauna in this county. Eleven thousand acres are in need of protec-
tion and 15,000 acres for enhancement
PENNSYLVANIA FOCUS AREA SUMMARY
Focus Area
Susquehanna River Lowlands
Middle Creek WMA-
Ontelaunee Resevoir Corridor
Marsh Creek
Bucks and Montgomery County Wetlands
Tobbyhanna - Gouldsboro Project
State Game Lands #'s 13, 57, and 66
State Game Lands # 180
Wayne County
Total
Protect
8300
2,000
1,500
LSOO
26,666
3,000
3,000
11,000
56,966
Enhance
2,500
500
300
500
5,200
15,000
5,000
15,000
44,000
Total
10,800
2,500
1,800
2,000
31,866
18,000
8,000
26,000
100,966
Delaware
The Milford Neck/Big Stone Beach focus area is composed of 12,000 acres
of wetlands and agriculture lands. The wetland type is primarily regularly
to irregularly-flooded tidal wetlands composed of salt marsh cordgrass,
salt hay, salt marsh shrubs, and common reed. The area contains about 5.7
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miles of Delaware Bay shorefront consisting of a low duneline behind a
silty-sand beach and is heavily used by waterfowl and shorebirds. Approxi-
mately 11,270 acres need to be protected and 730 acres enhanced.
During fall and winter, tens of thousands of waterfowl utilize this area for
feeding and resting. This area is also important for the production of black,
mallard, and wood ducks; shorebird species such as dapper, king and black
rails, willets, killdeer, least terns, and oyster catchers; numerous song birds,
woodcock, and wild turkey. Both bald and golden eagles are known to feed
in the area/ and they could eventually nest here.
A significant proportion of North America's shorebird population stops to
feed and rest in this area during migrations. The spring stopover is a critical
"refueling" stop where hundreds of thousands of shorebirds feed on horse-
shoe crab eggs along the shoreline. Because of the area's importance in this
regard, it has been included in the proposed acquisition area of the Interna-
tional Western Hemisphere Shorebird Reserve Network.
If the land remains in private ownership, attempts will be made to fortify
the shoreline (bulkheads, rip-rap, etc.) for development purposes. This
development and associated activity will result in the loss of these critical
shorebird feeding and resting areas, as well as valuable nesting and winter-
ing habitat for black ducks and other waterfowl. Future attempts to create a
deepwater port just offshore, if successful, will substantially degrade this
area's environmental value.
At present, this focus area is composed of 2,300 acres of land owned and
managed by the Delaware Division of Fish and Wildlife, 1,760 acres of land
owned and managed by the Delaware Wildlands (a local conservation
organization), and 9,500 acres of privately owned wetland (60%) and
agricultural land (40%).
Maryland
1. Sinepuxent and Chincoteague Bay Marshes (Worcester County)
Coastal embayed marshes adjacent to these coastal bays are used by
large numbers of wintering waterfowl, particularly black ducks. This
focus area contains the 7,100-acre Assateague Island National Seashore
which adjoins Chincoteague National Wildlife Refuge in Virginia,
Assateague State Park (680 acres) and E.A. Vaughn Wildlife Manage-
ment Area (1,751 acres). Approximately 15,000 acres of wetlands and
potential upland buffers remain in private ownership.
Black ducks, buffleheads, canvasbacks, Canada geese, Atlantic brant,
and greater snow geese are the most numerous wintering waterfowl
species within this area. This is an important area for waterfowl, egrets,
herons, shorebirds, woodcock, and peregrine falcons migrating along
the Atlantic coast. Over 30 nesting colonies of 17 species of gulls, terns,
herons, and egrets have been documented within this area. A small
population of brown pelicans and one pair of bald eagles also nest
within this area.
Private land within and adjacent to Assateague Island State Park and
Assateague National Seashore should be protected by means of acquisi-
tion or long-term conservation easements. The salt marsh habitat and
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adjacent buffer of wooded uplands and agricultural fields along the
west shoreline of Newport and Chincoteague Bays need to be pro-
tected from development. Approximately 20,000 acres need to be
protected and 2,650 acres enhanced.
2. Blackwater and Nantkoke River Marshes (Dorchester and Wicomico
Counties)
Vast expanses of fresh and brackish estuarine marshes are the outstanding
feature of this area. Four major types of waterfowl habitat are well
represented: the fresh estuarine bay marsh, brackish estuarine bay marsh,
brackish estuarine river marsh, and brackish estuarine bay. Many of these
marshes are adjoined by large tracts of sawtimber used by nesting bald
eagles and good sized agricultural fields.
The Blackwater-Nanticoke section is an important waterfowl area. Canada
geese, mallards, black ducks, and canvasbacks are most important Large
numbers of blue-winged teal use mis area during their fall and spring
migration. Approximately 8,000 canvasbacks roost on Fishing Bay and the
Nanticoke River along the east shore of Elliotts Island. Black ducks are
well distributed ever all three types of estuarine marsh, although most
occur in the brackish bay marsh. A fairly large number of black ducks
breed in brackish, estuarine bay marshes. Additional breeding waterfowl
include mallards, blue-winged teal, gadwall, and wood ducks. Large
numbers of wood ducks concentrate at the head of the Blackwater, Little
Blackwater, and Transquaking Rivers during their fall migration.
Breeding peregrine falcons have been reintroduced to this area. At least
three pairs of bald eagles nest within mis area. It is an important winter-
ing area for 60-70 bald eagles. The Nanticoke River, Marshyhope Creek,
lower Blackwater River, and Transquaking River are important spawning
areas for striped bass and shad. Other major species include blue crabs
and finfish such as white perch, alewife, grey seatrout, and eels. The
shallow pond, tidal creeks, and mud flats of this area are important to
feeding and migrating herons, egrets, and shorebirds.
This area contains the 11,216-acre Blackwater National and the 17,208-aoe
Fishing Bay Wildlife Management Area. Several impoundments on
Blackwater NWR require adequate water supply to achieve full manage-
ment potential for producing moist soil foods. Several open marsh water
management (OMWM) projects have been completed in this area. The
long-term effects of this management upon waterfowl and wetland
communities need to be evaluated. Protection of these habitats should be
accomplished through acquisition or long-term leases. The waterfowl
carrying capacity of this area can be improved through OMWM projects
in high-phase marshes, reduction of insecticide use (mosquito spray),
improved management of existing state and federal impoundments, and
improved management of adjacent agricultural uplands in this area.
Protection of private wetlands and adjoining buffers is best accomplished
by either conservation easements, tax incentive programs, or acquisition.
Due to the importance of this area for a wide variety of wildlife, 53,500
acres are identified for protection and 5,000 acres for enhancement.
3. Lower Eastern Shore Marshes (Wicomico, Somerset, and Worcester
Counties)
Salt estuarine bays and salt estuarine bay marshes are the principal
habitats of this area. The broad marshes along the estuarine bay shores
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and on the offshore islands are the only large areas of salt estuarine bay
marsh in the entire upper Chesapeake Bay region. Numerous brackish
estuarine river marshes border tidal streams that extend into the interior.
There are two fairly large brackish estuarine bay marsh - the Broad
Creek marsh and the Marumsco Creek marsh.
This area is most important to waterfowl during unusually cold winters,
when other waterfowl habitats in other areas become frozen over. The
saltwater areas ordinarily do not have the high densities of waterfowl
that are characteristic of other habitats in this region, but they are so
extensive that they contain more than 75% of the black ducks observed
in the winter. Black ducks are common in this area during the fall,,
winter, and early spring. Scattered black ducks also breed in this habitat
later in the season. Large numbers of blue-winged teal, widgeon, and
gadwall utilize impoundments managed in this area for widgeon grass.
Wintering waterfowl include canvasbacks, scaup, common goldeneyes,
buffleheads, widgeon, gadwall, and green-winged teal.
This area contains 23 active nesting colonies of terns, herons, and egrets.
Eight breeding pairs of nesting bald eagles occur within mis area. An
additional 40-50 bald eagles use this area as wintering habitat
This area contains seven state wildlife management areas totaling 24,650
acres plus an additional 2,573 acres of state-owned lands. Martin
National Wildlife Refuge (4,423 acres), Bloodsworth Island (5,361 acres),
and Smith Island are located within this area.
Water bodies in this area include the Pocomoke, Manokin, and Big Anne-
messex Rivers, Dividing and Nassawango Creeks, and large embayments,
including Pocomoke and Tangier sounds. The estuarine portion is a prime
area for production of oysters and clams, and many of the upper tributaries
are prime spawning and nursery areas for a variety of fishes.
Protection of wetlands and adjoining upland buffers should be accom-
plished via conservation easements, tax incentives to landowners, and
acquisition. The carrying capacity of this area might be increased by the
development of impoundments at carefully selected sites. The habitat
quality of the 2,800-acre impoundment at Deal Island Wildlife Management
Area could be improved by the development of interior dikes dividing this
large impoundment into several smaller manageable cells. A total of 34,000
acres are in need of protection. Enhancement is needed on 6,100 acres.
4. Dickenson Bay (Talbot County)
This brackish estuarine bay on the north shore of the Choptank River
has been one of the State's most important wintering areas for Canada
geese, black ducks, and canvasbacks. The adjoining uplands and tidal
creeks provide additional feeding areas for wintering black ducks,
mallards, and Canada geese. The small island (10 acres) in Dickenson
Bay is utilized by nesting black ducks, common terns, and green herons.
At least one pair of bald eagles nest nearby and use this area for feeding.
Protection of this area should be accomplished by conservation ease-
ments and acquisition. Upland buffers should be established to protect
the value of this area to wintering waterfowl This area is in private
ownership. Presently, commercial gunning and residential development
are threatening the value of this area to wintering waterfowl. Approxi-
mately 1,250 acres have been identified for protection.
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5. Patuxent River Marshes (Prince George's, Anne Arundel, and Calvert
Counties)
The principal habitats are the open estuarine bays and the estuarine river
marshes. The freshwater portion of the marsh is the largest of its type in
the upper Chesapeake Bay region, occupying approximately 2,000 acres.
A great variety of diving ducks and dabbling ducks winter in this area.
Total waterfowl populations, however, are lower than would be expected
in habitats of such quality. Black ducks, mallards, and Canada geese are
abundant during the winter period. Excessive human disturbance and
residential development threaten the value of this habitat Conservation
easements on private lands would be beneficial.
This area has been designated as one of the State's Scenic Rivers.
Approximately 5,125 acres are under state ownership and managed for
wildlife. An additional 6,300 acres is managed by county governments.
The Patuxent River marshes are a major migration area for rails,
particularly sora rails. Four breeding pairs of bald eagles nest within
this area. Approximately 14,500 acres have been identified for protec-
tion and 500 acres for enhancement actions.
MARYLAND FOCUS AREA SUMMARY
Focus Area
Protect Enhance Total
Sinepuxent & Chincoteague Bay Marshes 20,000
Blackwater & Nanticoke River Marshes 53,500
Lower Eastern Shore Marshes 34,000
Dickenson Bay 1,250
Patuxent River Marshes 14,500
2,650 22,650
5,000 58,500
6,100 40,100
1,250
500 15,000
Total
123,250 14,250 137,500
Virginia
1. Virginia Eastern Shore (Seaside) including Assawoman, Metomkin,
and Cedar Islands (Accomack County)
The area includes extensive coastal salt marshes, barrier beach, and
interior marshes adjacent to the mainland. The area provides high
value habitat to wintering, migratory, and breeding black ducks, and
wintering habitat for a diversity of other waterfowl species such as
Atlantic brant, Canada geese, greater snow geese, goldeneyes, buffle-
heads, mergansers, and seaducks. The beach areas provide nesting
habitat for nearly two dozen species of colonial nesting birds and other
migratory birds including the endangered piping plover, brown
pelican, and Wilson's plover. Migrating raptors including the endan-
gered peregrine falcon make heavy use of these areas during migration.
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Wading and shore birds abound in this habitat The area is an impor-
tant nursery area for numerous economically important finfish and
shellfish species. Approximately 14,500 acres need protection and 500
acres need enhancement.
2. Virginia Eastern Shore (Bayside) (Accomack County)
This area primarily consists of tidal brackish high marshes bordering
the eastern side of the Chesapeake Bay from Saxis south to Hack Neck.
The marshes occurring in this area support populations of migrating,
wintering, and nesting black ducks. Other dabbling ducks use the area
during migration wintering as do Canada geese. Many of the marshes
in this area hold good potential for enhancement utilizing management
techniques. Associated wetlands are valuable to numerous species of
finfish and shellfish as nursery and production areas. Seven thousand
acres are identified for protection and 800 acres for enhancement.
3. Pamunkey River Marshes (King William and New Kent Counties)
The tidal fresh to brackish marshes and wooded swamps associated with
this area provide important migration and wintering habitat to a signifi-
cant portion of Virginia's puddle duck population including black ducks
and mallard as well as Canada geese. Breeding wood duck populations
are high. These marshes are valuable as both spawning and nursery areas
for several anadromous fish species including striped bass, American
shad, and river herring. The vicinity is used by nesting and wintering
American bald eagles. Approximately 9,200 acres are in need of protec-
tion and 100 acres for enhancement
4. Chickahominy River Marshes (New Kent, Charles City, and James
City Counties)
The tidal fresh to slightly brackish marshes in this system provide
migration and wintering habitat to a number of puddle duck species
including black duck, mallard, pintail, green-winged teal, and blue-
winged teal. The area is an important wood duck nesting area. The
area is heavily used by nesting, summering, and wintering American
bald eagles. Nesting ospreys are numerous as are wading birds.
Several species of anadromous fish utilize the area for spawning and
nursery phases of their life cycle. This focus area would include 3,650
acres for protection and 50 for enhancement.
5. James River Marshes (Prince George, Charles City, and Surry Counties)
The tidal fresh marshes in this system are important puddle duck
migration and wintering habitat for black duck, mallard, pintail, green-
winged teal, American widgeon, and gadwalL Canada geese make
heavy use of these marshes. The highest summer concentration of
American bald eagles in the mid-Atlantic states occurs in this stretch.
Eagle nesting and wintering is also heavy in mis area. Important
anadromous fish species such as striped bass, American shad, river \
herring, and an occasional sturgeon utilize the area for spawning and
nursery activities. Approximately 3,650 acres need protection and 50
acres need enhancement
6. Back Bay Marshes North Landing River (Virginia Beach)
The freshwater marsh complexes in this area provide excellent habitat
for migrating and wintering black ducks as well as a vast diversity of
other waterfowl including mallard, pintail, American widgeon, gad-
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wall, shoveler, green-winged teal, blue-winged teal, greater snow geese,
Canada geese, and tundra swan. Highly productive wood duck breed-
ing habitat is abundant adjacent to the North Landing River wetlands.
The large open-water areas adjacent to these wetlands have historically
been cast sources of submerged aquatic vegetation (SAV) although
currently the supply is greatly reduced. Diving duck species such as
canvasback, scaup, ring-necked duck, and ruddy are plentiful as are
American coots in years of good SAV production. The area is utilized
by nesting osprey and numerous other migrating raptors including the
endangered peregrine falcon. The area is an important freshwater fish
spawning and nursery area and supports economically important
populations of white perch, eels, and blue crabs. The area is currently
under great pressure from development interest from the fast-growing
Virginia Beach/Hampton Roads urban complex. Much of the problem
associated with the deterioration of SAV resources is linked to water
quality degradation from residential and agricultural runoff. In addi-
tion to wetland protection, buffer strip protection is essential if the "Bay"
is to be restored. A total of 8,800 acres have been identified in this focus
area for protection (8300) and enhancement (500).
7. Rappahannock River Marshes (Essex, Middlesex, Richmond, and
Lancaster Counties)
These tidal fresh to brackish marshes provide high-quality diverse migra-
tory and wintering habitat for black ducks and other waterfowl such as
mallards, blue-winged teal, green-winged teal, pintail, Canada geese, and
tundra swan. The area provides high-quality wood duck breeding habitat
The area provides excellent bald eagle nesting, summering, and wintering
habitat The area is extremely important for spawning and nursery activi-
ties of striped bass, American shad, and river herring. Blue crabs and
oysters abound in the downstream reaches. Approximately 4,150 acres are
in need of protection efforts and 200 acres for enhancement.
8. Mattaponi River Marshes (King and Queen, and King William Counties)
These tidal fresh to brackish marshes are very similar to the Pamunkey
River complex; however, they do not support the numbers of waterfowl
found on the Pamunkey. Migrating and wintering black ducks as well
as mallards and teal use the area along with limited numbers of Canada
geese. American bald eagles are observed year round in the watershed.
Striped bass, American shad, hickory shad, and river herring utilize this
area for spawning and nursery activities. This focus area includes 2,500
acres for protection and 100 acres for enhancement.
9. York River Marshes (Gloucester, York, and James City Counties)
These areas are tidal brackish high marshes that support moderate
numbers of migrating and wintering black ducks, mallards, and Canada
geese. Adjacent open water areas are populated with canvasback,
scaup, bufflehead, goldeneyes, and ruddy ducks. The marshes hold
good enhancement potential for waterfowl. Several species of economi-
cally important finfish and shellfish utilize these areas for nursery
activities. Fourteen hundred acres are in need of protection and 250
acres for enhancement.
10. Western Bayshore Marshes (Reedville to Mobjack Bay)
(Northumberland, Lancaster, Middlesex, and Matthews Counties)
These tidal brackish marshes are similar to the Eastern Shore Bayside
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wetlands. Although total waterfowl numbers are somewhat modest,
they do provide important migration and wintering habitat for black
duck as well as mallard, Canada geese, and tundra swan. The area is
heavily uHI.iy.ed by nesting osprey and many shore and wading bird
species. Virtually all of these marshes are adjacent to important finfish
and shellfish nursery areas. These marshes possess good potential for
waterfowl enhancement projects. This focus area includes a total of
2,475 acres for protection and 275 acres for enhancement.
VIRGINIA FOCUS AREA SUMMARY
Focus Area
VA Eastern Shore (Seaside)
VA Eastern Shore (Bayside)
Pamunkey River Marshes
Chickahominy River Marshes
James River Marshes
Back Bay/N. Landing River Marshes
Rappahannock River Marshes
Mattaponi River Marshes
York River Marshes
Western Bayshore Marshes
(Reedville-Mobjack Bay)
Total
Protect
14,500
7,000
9,200
4,400
3,650
8,300
4,150
2,500
1,400
2,475
57,575
Enhance
500
800
100
50
50
500
200
100
250
275
2,825
Total
15,000
7300
9300
4,450
3,700
8,800
4,350
2,600
1,650
2,750
60,400
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