Mitigation
Site
Type
Classification
A Methodology To
Classify Pre-Project
Mitigation Sites And
Develop Performance
Standards For
Construction And
Restoration Of
Forested Wetlands:
Results of an EPA-Sponsored Workshop
Falls Creek State Resort Park • Pikeville, Tennessee -August 13-15,1989
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MiST:
A METHODOLOGY TO CLASSIFY PRE-PROJECT MITIGATION SITES
AND DEVELOP PERFORMANCE STANDARDS
FOR CONSTRUCTION AND RESTORATION OF FORESTED WETLANDS:
Results of an EPA-sponsored Workshop
Edited by
Timothy A. White
James A. Allen
Stephen F. Mader
Dennis L. Mengel
Donna M. Perison
D. Thompson Tew
Performed for
Region IV Wetlands Planning Unit
U.S. Environmental Protection Agency
Atlanta, Georgia
Hardwood Research Cooperative
North Carolina State University
Raleigh, North Carolina 27695-8002
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ACKNOWLEDGEMENTS
This document summarizes the results of a Workshop held
August 13-15, 1989 at Fall Creek Falls State Resort Park ir.
Pikeville, TN and compiles the expertise of many individuals
throughout the Southeast. The editors are grateful to the
following individuals for their contributions at the Workshop and
to this report:
Mr. William Ainslie
U.S. E.P.A.
345 Courtland St., NE
Atlanta, GA 30365
(404) 347-2126
Dr. Clark Ashby
Dept. of Botany
So. Illinois Univ.
Carbondale, IL 62901
(618) 536-2331
Dr. Charles Belin
US Army Corps of Engineers
P.O. Box 889
Savannah, GA 31402-0889
(912) 944-5838
Mr. Ellis J. Clairain
US Army Corps of Engineers
Waterways Expt. Stn.
P.O. Box 631
Vicksburg, MS 39180
(601) 634-3774
Mr. David Cobb
Dohan Engineering
P.O. Box 528
Madisonville, KY 42431
(502) 821-7343
Mr-. Jeff Furness
Texas Gulf, Inc.
P.O. Box 48
Aurora, NC 27806
(919) 322-8249
Mr. Bob Bay
U.S. Fish and
Wildlife Service
P.O. Box 845
Cookeville, TN 38503
(615) 528-6481
Dr. Mark Brinson
Biology Dept.
East Carolina Univ.
Greenville, NC 27858
(919) 757-6307
Dr. Andre Clewell
Society of
Ecol. Restoration
1447 Tallevast Rd.
Sarasota, FL 34243
(813) 355-5065
Mr. Wayne Davis
Dept. Fish & Wildlife
Resources
#1 Game Farm Road
Frankfort, KY 40601
(502) 564-5448
Dr. William Harms
S.E. Forest Expt. Stn.
U.S. Forest Service
2730 Savannah Highway
Charleston, SC 29407
(803) 556-4860
Dr. Ronnie Haynes
U.S. Fish & Wildlife
Service
75 Spring Street
Atlanta, GA 30303
(404) 331-3580
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Mr. Delbert Hicks
U.S. E.P.A.
Environmental Services Div.
College Station Road
Athens, GA 30 613
(404) 546-2294
Mr. Glenn Kelley
Kentucky State Soil Scientist
333 Waller Ave.
Room 305
Lexington, KY 40504
(606) 233-2751
Dr. Russell Lea
College of Forest Resources
N.C. State Univ.
Box 8002
Raleigh, NC 27695-8002
(919) 737-3674
Dr. Wade Nutter
Univ. of Georgia
School of Forest Resources
Athens, GA 30602
(404) 542-1772
Mr. Jim Sandusky
Peabody Coal Company
Will Scarlet Mine
Stonefort, IL 62987
(618) 777-2591
Mr. Thomas Welborn
U.S. E.P.A.
345 Courtland St., NE
Atlanta, GA 30365
(404) 347-2126
Mr. Charles L. Hooks
Univ. of Illinois
RR #1 Box 164
Percy, IL 62272
(618) 965-9211
Dr. William Kruczynski
U.S. E.P.A., Sabine Island
Gulf Breeze, FL 32561-5299
(904) 932-5311
Dr. Jack Nawrot
So. Illinois Univ
Coop. Wildlife
Research Laboratory
Carbondale, IL 62901
(618) 453-2801
Mr. Phil 0'Dell
Kentucky Div. Water
Frankfort Office Park
18 Reilly Road
Frankfort, KY 40601
(502) 564-3410
Mr. Russell Theriot
US Army Corps of Engineers
Waterways Expt. Stn.
P.O. Box 631
Vicksburg, MS 39180
(601) 634-2733
Mr. Don Walker
Kentucky Dept. of
Environmental Protection
Division of Water
18 Reilly Road
Frankfort, KY 40601
(502) 564-3410
In addition, the editors express their appreciation to B.
Arville Touchet, Louisiana State Soil Scientist, for his
review and comments and to J.W. Walden, N.C. State University
School of Design for the cover illustration.
Development and preparations for the Workshop and this
document was supported through TVA Contract #TV-75524A.
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PREFACE
The goals of the Clean Water Act (CWA) are to protect and
maintain the chemical, physical, and biological integrity of the
nation's waters. The Environmental Protection Agency (EPA) and
Army Corps of Engineers are given regulatory authority for the
discharge of dredged or fill material into waters of the United
States. Section 404 of the CWA has become the primary mechanism
for the protection of wetlands by Federal authorities. While "no
net loss" of wetlands - an interim goal of a stable national
wetlands inventory in terms of acreage and function - has been
identified by some groups as a top national priority (The
Conservation Foundation, 1988) , there remains the fundamental
technical challenge of restoring or creating new wetland
resources to offset inevitable or unavoidable losses that will
continue to occur.
Lack of standardization has led to inconsistencies in the
evaluation of mitigation plans by state and federal agencies
across EPA Region IV (Alabama, Florida, Georgia, Kentucky,
Mississippi, North Carolina, South Carolina, and Tennessee). EPA
Region IV and the Tennessee Valley Authority approached the North
Carolina State Hardwood Research Cooperative (HRC) to conduct a
workshop to address these problems. The Workshop on BLH Forest
Mitigation of Disturbed Sites was held at the Fall Creek Falls
State Resort Park near Pikeville, Tennessee on August 13 - 15,
1989. The summaries of the deliberations of this Workshop and
subsequent review are contained in this document.
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HRC proposed that consistency in the evaluation of mitigation
plans could be reached by developing a framework to classify
pre-construction mitigation sites. The classification system
would be used to objectively sort out the range of potential
options available to monitor the success of mitigation projects.
This framework could also serve to enhance communication
throughout the Region. Consequently, a prototype classification
system was developed by the HRC and presented to Workshop
participants which they adopted and refined.
The end result of the Workshop is the Mitigation Site Type
Classification System (MiST) . A decision was made early in the
Workshop to expand the initial focus from BLH systems to a more
regional approach encompassing all freshwater forested wetlands.
The classification system is contained within this document.
MiST is composed of three parts including 1) the
classification of mitigation sites; 2) the statements of
performance standards for sites undergoing mitigation and; 3) the
measurements required to evaluate mitigation performance.
Performance is tied to a Reference Forest Ecosystem.
A fundamental assumption of MiST is that the potential for
success (or, conversely, risk of failure) in forested wetland
replacements is related to pre-replacement site conditions.
Importantly, MiST requires a monitoring program of all forested
wetland mitigations and monitoring intensity is related to the
original site condition (perceived risk of failure).
While the goals of the Workshop were to address concerns
related specifically to Section 404, an additional benefit of
MiST is the potential for its use outside of regulatory programs.
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Classification of mitigation sites and development of
performance standards and monitored characteristics can lead tc
better restoration of lands currently under consideration for
conversion to forested wetland ecosystems through the
Conservation Reserve Program. Thus, MiST can also assist in an
increase in the quality and quantity of the nation's wetland
resource. Nevertheless, while MiST can assist in the evaluation
of mitigation plans contingent to 404 permitting, it is not
intended to supercede avoidance policies.
This document currently should be regarded as a DRAFT for use
by Region IV EPA and interested parties including other federal
and state agencies and forested wetland mitigators. It should
not be considered an official EPA publication at this time. The
editors welcome comments and criticisms of the MiST
classification system and suggestions for its refinement.
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TABLE OF CONTENTS
Page
Acknowledgements ii
Preface iv
List of Tables and Figures viii
PART I: EPA PERSPECTIVES 1
PART II: WORKSHOP CHARGES 19
PART III: SUMMARIES OF WORKING GROUP DELIBERATIONS
Vegetation Working Group 27
Soils Working Group 34
Hydrology Working Group 40
Water Quality Working Group 4 6
Habitat Working Group 54
PART IV: USE OF MiST IN THE FIELD AND SELECTION
OF A REFERENCE FOREST ECOSYSTEM
Using MiST in the Field: Suggestions and Key
to the Mi'ST Classification 60
Selection of a Reference Forest Ecosystem:
Issues and Approaches 71
GLOSSARY 81
LITERATURE CITED 83
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LIST OF TABLES
Pagg
Workshop Charges
Table 1. Some functions of forested wetland ecosystems 21
Vegetation Working Group
Table 1. MiST Classification for Vegetation 28
Table 2. Monitoring Required for MiST Vegetation
Performance Standards Assessment 33
Soils Working Group
Table 1. MiST Soil classification system 35
Table 2. Chemical and physical factors to be measured
on the reference and mitigation sites 37
Table 3. Measurement schedule of factors by disturbance
class on the reference and mitigation sites 38
Hydrology Working Group
Table 1. MiST Classification System for Hydrology 41
Table 2. Measurements required for MiST Hydrology
Performance Standards 43
Table 3. Frequency of monitoring of MiST Hydrologic
Performance Standards 44
Water Quality Working Group
Table 1. Monitoring of Water Quality Parameters 50
Habitat Working Group
Table 1. Potential mitigation measures to benefit fish
and wildlife during replacement of freshwater
forested wetland ecosystems 57
Table 2. Habitat Mitigation Phases 58
Key to the use of the Mitigation Site Type
Classification System {MiST) 68
LIST OF FIGURES
EPA Perspectives
Figure 1. Generalized Section 404 Permit Process 4
Figure 2. Generalized Section 404(b)(1)
Guidelines Evaluation Process 5
Figure 3. Council on Environmental Quality Mitigation
Types (40 CFR Part 1508.20 a-e) 7
Figure 4. Mitigation Credit Ratios 11
Figure 5. Options with Compensatory Mitigation 12
Figure 6. Ranking of Mitigation Options 16
Water Quality Working Group
Figure 1. Successful restoration of water
quality parameter 48
Figure 2. Failed restoration of water quality parameter 4 9
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PART I
EPA PERSPECTIVES
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MITIGATION OF BLH WETLANDS AND THE SECTION 404 PERMIT PROGRAM:
EPA PERSPECTIVES
William Ainslie and William L. Kruczynski
INTRODUCTION
The growing realization of the importance of wetland
habitats, and the fact that over one-half of our nation's
wetlands have been lost, has resulted in several developments
providing increased protection to our remaining wetland
resources. In 1987, at the request of EPA, the Conservation
Foundation convened the National Wetlands Policy Forum (NWPF)
The goal of the NWPF was to take a broad view of how this natioTi
can better protect and manage the remaining wetland resources. In
response to the Forum's Final Report, the Agency has initiated an
action plan with a goal of no net loss of wetlands. President
George Bush has been quoted to be in direct support of this goal.
Development of wetland areas has been regulated at the
national level since 1972 under Section 404 of the Clean Water
Act. Section 404 requires a permit be issued before any fill
material is placed in wetlands. The apparent dilemma of how a
permitting program can remain in effect while achieving a goal of
"no net wetland loss" has been approached by mitigating
unavoidable wetland losses through wetland creation. However,
there have been inconsistencies within the Agency in assessing
the status of proposed mitigation sites and in the criteria used
to evaluate mitigation projects and proposals. In addition, EPA
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Region IV has expressed a need to develop standardized criteria
to evaluate the success of permitted mitigation projects. Ic is
Region IV's policy to only allow replacement mitigation for
wetland communities in which replacement mitigation is proven
possible.
The National Workshop on Bottomland Hardwood Mitigation of
Disturbed Lands was convened to address these problems for 3LH
wetland communities. This Workshop evolved through discussions
between EPA Region IV and the Tennessee Valley Authority (TVA).
An interagency agreement between TVA and EPA utilized TVA's
cooperative agreement with North Carolina State University's
Hardwood Research Cooperative (NCSU-HRC) to organize and
facilitate the Workshop because of their research expertise in
BLH wetland functions and creation and their knowledge of
industry and development impacts on forest habitats.
SECTION 404 - A HISTORICAL PERSPECTIVE
The goal of the Clean Water Act (CWA) is to "restore and
maintain the chemical, physical and biological integrity of the
Nation's waters." Section 404 of the CWA is the primary Federal
wetlands statute and requires receipt of a permit for placement
of dredged or fill material into waters of the United States of
which wetlands are a subset. Discharges are allowed after
receipt of a Corps of Engineers (COE) permit if these discharges
are not restricted by EPA pursuant to its veto authority under
Section 404(c) of the Act.
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The Section 404 Permitting Process
The Section 404 permit review process is summarized in Figure
1. Applicants submit a permit application to the COE.
Applications are advertised in public notices which are
distributed for review. The public and resource agencies (EPA,
U.S. Fish and Wildlife Service, National Marine Fisheries
Service, State regulatory agencies) provide comments to the COE
concerning potential environmental effects of the proposed
project. The COE determines whether a public hearing and/or an
Environmental Impact Statement is required to evaluate potential
environmental impacts. Finally, the COE makes a determination
whether it is in the public's interest to issue a permit.
If the COE District Engineer serves a notice of its intent to
issue a permit for a project which Federal resource agencies have
determined would result in unacceptable environmental impacts,
agencies can elevate that decision to higher authority for review
as specified in Memoranda of Agreement between the COE and
resource agencies (Section 404(q)). In addition, EPA can veto a
permit or predesignate areas as unsuitable for receipt of fill
material under its authority given in Section 404 (c) . However,
that option is not exercised frequently because it is very labor
intensive and may be highly political.
The Regulatory Reform Task Force targeted the Section 404
program for reform in 1980 which resulted in new 404(q) Memoranda
of Agreement which gave the COE the sole authority to determine
whether a project could receive elevated review and at what level
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Figure 1. Generalized Section 404 Permit Process
the review would take. This development, and a reluctance by EPA
to exercise its Section 404(c) veto, resulted in Region IV
increasing the number of recommendations that included wetlands
creation mitigation in exchange for wetland losses, even when
wetland losses were avoidable.
Section 404(b)(1) Guidelines
Section 404(a) states that the COE shall administer the
permitting program. Section 404(b) requires that EPA, in
conjunction with the COE, will develop guidelines by which permit
applications are reviewed. The Section 404(b) (1) Guidelines are
summarized in Figure 2 (40CRF230). There are four "Guidelines"
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Figure 2. Generalized Section 404 (b) (1) Guidelines
Evaluation Process
NO DISCHARGE WILL BE PERMITTED IF ANY ONE OF
THE FOLLOWING 13 TRLJF:
Practicable Alternatives Exist Which Would Have Lasa
Adverse Impact on the Aquatic Ecosystem
(Unleaa the Alternative Would Have Other Significant
Adverse Environmental Consequences!
'Practicaoie' Means Availaoig ana CapaOle ot
eing Dona Altar Taking into Consideration Costs.
Existing Tecnnoiogy, ana Logistics
II a Non-Mater Dapanoent Oiscnargg At tacts a\
Special Aquatic Site, Practicaoie Alternatives
are Presumed to Exist •
It Causes or Contributes to Significant Degradation ot
Waters ol the United States
t
All Appropriate and Practicable Steps Have Not Been Taken to
Minimize Potential Adverse Impacts to the Aquatic Ecosystem
• 'Special aquatic sites' include wetlands, mudflats,
vegetated shallows, coral reefs, and rlffig/pool complexes
and EPA has adopted a policy that these guidelines should be
evaluated sequentially; failure to satisfy any one of the four
steps should result in denial of the permit application.
Guideline 1 (33CFR230.1(a)) requires that no discharge of
dredged or fill material into waters of the United States shall
be permitted if there is a practicable alternative which would
result in less environmentally damaging impacts. For non-water
dependent projects, the regulations establish a rebuttable
presumption that such alternatives exist. The "alternatives
test" is the threshold which must be satisfied before a Section
404 permit is issued. "Practicable" takes cost, distance,
technology, purpose, and logistics into consideration.
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Guideline 2 (33CFR230.1(b)) states that no permit should be
granted if it causes or contributes to a violation of ar.y
applicable state water quality standard, toxic effluent standard,
jeopardizes an endangered species or habitat, or impacts a marine
sanctuary. If this requirement is met, the next step is to
determine whether the discharge will result in significant
degradation of waters of the United States (Guideline 3)
(33CFR230.1(c)). This includes ecological degradation,
degradation to fishery resources or aquatic ecosystems, human
health or welfare.
If Guidelines 1 through 3 are met, the final step in the
Section 404 (b) (1) analysis is that no discharge will be permitted
unless efforts have been made to minimize potential adverse
impacts (Guideline 4, 33CFR 230.1(d)). This is the step in the
process where replacement mitigation has been used to replace
habitat values lost due to filling activities.
History of Wetlands Mitigation
Although the word "mitigation" does not appear in the CWA and
has not appeared in any Section 404 regulations until the latest
issue of the Corps Regulations (1986, 33CFR320.4(r)), mitigation
has been used in the permitting process since the inception of
the program in an attempt to minimize wetland losses. One
meanx-.g of "mitigation" is to reduce adverse impacts (Figure 3) .
If a project is reduced in size or modified to the point where
the impacts have been reduced so that there is no significant
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Figure 3. Council on Environmental Quality Mitigation
Types (40 CFR Part 1508.20 a-e)
1. Avoiding the impact altogether by not taking a certain
action or parts of an action.
2. Minimizing impacts by limiting the degree of magnitude
of an action and its implementation.
3. Rectifying the impact by repairing, rehabilitating, or
restoring the affected environment.
4. Reducing or eliminating the impact over time by
preservation and maintenance operations during the
life of the action.
5. Compensating for the impact by replacing or providing
substitute resources or environments.
degradation (Guideline 3), then a project is determined to be
acceptable.
The Federal government has struggled since the inception of
the program in 1972 with the role of wetland creation/replacement
mitigation in the Section 404 permitting process. Many times
issuance of a permit was considered for projects which reviewing
agencies considered nonpermittable, but agencies did not have the
ability to stop permit issuance. Consequently, the agencies
sought to compensate for wetland losses through replacement
mitigation. This approach seemed to work and some resources were
returned for wetlands that were lost through filling. However,
many wetlands that were lost were highly valuable, and many times
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the promised mitigation was never performed or did not work.
Also, many of the permitted activities did not conform to
Guideline 1, i.e. there were practicable alternatives which would
have avoided wetland impacts. This practice of considering
replacing wetland losses for any project became the standard
procedure in permit review during the period of regulatory
reform.
Section 404 Today
Seventeen years after the inception of the program,
regulators are still wrestling with the role of mitigation in
Section 404. The advent of "no net loss", as recommended by the
NWPF and supported by President Bush, has resulted in closer
scrutiny of the alternatives analysis (Guideline 1) by the Corps,
EPA, and other resource agencies.
President Bush has been quoted as saying "All wetlands, no
matter how small, should be preserved." Such a goal precludes a
permitting program; if every wetland is to be preserved, no
permits can be issued for filling of wetlands. Given the current
Federal law, which does not preserve wetlands but regulates
filling activities, regulators are viewing the President's
statement as a goal consistent with the goal of the NWPF, i.e.,
no net wetland loss. For permitted wetland fills, compensatory
replacement mitigation must be included to achieve no net wetland
loss.
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At the national level, the COE and EPA have drafted an
interagency mitigation policy; however, basic philosophic
differences in the role of mitigation in the Section 404(b)
review must be resolved before a joint policy is finalized. The
difference in opinion between the agencies on the role of
mitigation in the alternatives analysis resulted in EPA's Section
404(c) veto of a COE permit in the Attleboro Mall case. It is
EPA's position that replacement mitigation should not be part of
the alternatives analysis. Practicable alternatives include
sites or methods or project modifications which would result in
less environmental damage. It does not include replacement of
m
losses through creation. Some COE Districts, however, continue
to opine that the promise of replacement of wetlands is a less
environmentally damaging alternative than a project without
mitigation. This issue must be resolved at the national level.
EPA Region IV has adopted the position that if a project
conforms to the Section 404 (b) (1) Guidelines, mitigation of
wetland losses may be an acceptable option to replace losses.
Replacement mitigation is an acceptable option in cases where the
impacts to wetlands are not significant enough to warrant permit
denial. Compensatory mitigation could be included as a special
condition to a COE permit for projects where there are no less
environmentally damaging alternatives (Guideline 1), no statute
is violated (Guideline 2), the impacts have been minimized
(Guideline 4) and have been determined to be not significant
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(Guideline 3) or could be rendered insignificant with replacement
mitigation.
EPA Region IV has adopted a policy that projects which
conform to the Section 404 (b) Guidelines and whose impacts can be
made insignificant through proven compensatory replacement
mitigation techniques will perform the mitigation at an
acceptable credit ratio dependent upon the mitigation type.
These ratios are summarized in Figure 4 and are presented as
guidance to assure standardization of the mitigation requirement
among permit reviewers and agencies. Exchange and preservation
ratios should be determined on a case-by-case basis. The
definitions of these mitigation options are given below.
MITIGATION OF FORESTED WETLAND SYSTEMS
History
The word mitigation was first defined in the regulatory
context in the 1977 regulations of the National Environmental
Policy Act (NEPA). Mitigation means- to "moderate the intensity
or to lessen the impacts" of a particular project. NEPA lists
five different ways in which impacts can be mitigated (Figure
3), including impact avoidance (1), minimizing the impacts (2),
and compensating for losses (5) through restoration and
replacement.
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Figure 4. Mitigation credit ratios.
Mitigation Type Acres mitigated acres filled ratio
Restoration 1.5 : 1 or 1 : 1, if upfront
Creation 2 : 1 or 1 : 1, if upfront
Enhancement 3 : 1 or 2 : 1, if upfront
Exchange case by case basis
Preservation case by case basis
Types of Mitigation
EPA recently completed a report entitled "Wetland Creation
and Restoration: The Status of the Science" (Kusler and Kentula
1990). This report provides some standardization of the
mitigation process including an analysis of where mitigation fits
into the Section 404(b) review processs. In addition, it define
project types where mitigation is an acceptable option, what
kinds of and with what assurance communities can be replaced, and
what criteria are used to judge the success of a mitigation
project.
The mitigation options which are discussed in the EPA
document are listed in Figure 5. It is important for regulatory
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Figure 5. Options with compensatory mitigation
Types
Restoration
Creation
Enhancement
Exchange
Preservation
Timing
Up-front (before)
Concurrent
After
Location
On-site
Off-site
Community
In kind
Out of kind
former wetland, no or few functions
made from a different community
increases certain wetland functions
enhancement to the extreme; hard to evaluate
use only if area is not regulated
most prudent; require if unknowns exist
encouraged for typical projects
discouraged
same watershed or ecosystem
different watershed
same species composition
different species composition
activities to have standardized definitions of mitigation
options. Restoration is defined as converting a former wetland,
which is currently performing few wetland functions, to its
previous capabilities. For example, a degraded wetland with
little or no habitat value could be restored through
re-establishing the hydroperiod and/or vegetation to their former
condition.
Creation converts a non-jurisdictional community into a
wetland community. Scraping down an upland area to bottomland
elevations could result in a created wetland. Surface mining
operations generally alter the site so completely that wetland
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replacement on mined land would almost always be considered
creation even though a wetland may have once occupied the site.
Enhancement is performed as a result of a management
decision. Enhancement results in improving some wetland functions
often at the expense of other functions. For example, a typical
enhancement project would convert an historically impounded marsh
into a tidal area by breaking the dikes. This would result in
reconnecting the wetland to tidal waters. However, this
enhancement may result in reduced duck or wading bird habitat
provided by the impoundment. In this case, a management decision
was made to allow export of productivity to fisheries in adjacent
waters instead of utilization within the impoundment by wading
birds.
Exchange is enhancement taken to the extreme; it is
converting one wetland type into another type. For example,
deposition of dredged material in open shallow water may result
in marsh creation in exchange for an open water community.
Determining whether an ecological benefit has occurred in such a
circumstance is difficult since the two systems are judged by
different criteria.
Preservation is another compensatory mitigation option which
EPA feels should be considered only under special circumstances
following careful and extensive consideration of all available
options. Preservation results in the maintenance of wetland
functions in an existing tract to compensate for on-site project
disturbances. The preserved land may be on-site or off-site and
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is usually donated to an organization such as the Audubon Society
and/or a local or state resource agency. This is an approach
which is frequently proposed by applicants with substantial
resources and may be viewed by some as purchasing a permit. Since
the ethical nature of this approach is questionable at best,
preservation should be used only in very unusual circumstances
and usually in combination with different mitigation options. For
example, preservation may be used to compensate for the time that
created or restored wetlands become fully functional.
Mitigation Options
Additional mitigation options which must be considered in the
permit review process are listed in Figure 5. Mitigation can be
accomplished up-front (i.e. before the impact), concurrent, or
after the impact has occurred. An applicant should get more
"credit" if a constructed wetland system is in place before the
impacts occur. Concurrent mitigation should be encouraged for
typical mitigation projects so that it is part of the permit
review process and not a "tag-on project." After-the-fact
mitigation should be discouraged since recent studies show that
it may not be performed or may be performed poorly once the
development project is completed.
Another mitigation option includes the location of the
constructed wetland ecosystem. On-site mitigation is defined in
the EPA manual as "within the watershed" and should be encouraged
since it ensures that the replacement wetland is situated in the
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same ecosystem as the one which is removed through filling.
Off-site mitigation is within a different watershed and should
only be acceptable in unusual circumstances.
Different community types could be established during
mitigation projects. In-kind mitigation should be encouraged
since it replaces the same community type which was lost.
Out-of-kind mitigation may be an acceptable option in
circumstance where it is not feasible or desirable to replace the
same community type. For example, it may be determined that the
habitat function of an ecosystem could be improved by replacing a
common habitat type with a different habitat type.
Ranking of Mitigation Options
The EPA mitigation report presents framework in which
mitigation options can be evaluated through development of a
mitigation matrix (Figure 6). This matrix can be used to help
standardize the decision making process in evaluating a wide
range of potential mitigation options.
The ranking of options given in the matrix is the result of
weighting the different mitigation options. For example,
restoration (3) is ranked higher than other options since more
credit is given to restoring a degraded wetland to full function
than creating (2) a wetland from a functional uplands or
enhancing (1) an existing wetland.
By assigning values to other mitigation options, one can
compare the different mitigation projects by summing the values
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Figure 6. Ranking of mitigation options.
RESTORATION (3)
CREA TION (2)
OPTIONS
Timing
Community
type
Timing
Community
type
Site location
Option score
ENHANCEMENT (1)
Upfront (3)
Concurrent (2)
Post (1)
Timing
Community
type
Site location
Option score
for the options. Thus, restoring, upfront, in-kind and on-site
is rated the best mitigation option given in Figure 6 since that
combination receives a value of 12 based upon the suggested
weighting of options. Conversely, creating, after-the-fact,
out-of-kind, off-site wetlands would only receive a value of 5.
Regulators could use such a decision matrix to determine
whether a proposed mitigation project could be permitted by
setting an acceptable level of mitigation combinations. For
example, if the acceptance value is set at 9 in the proposed
weighting, mitigation options which yield a value of 9 or greater
could be approved for the project. This also allows some
flexibility in options available to the developer. Thus,
16
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acceptable compensation for filling of a Spartina marsh could be
accomplished through creation of upfront, in-kind, and on-site
(11). However, the applicant could not create, concurrently, an
out-of-kind wetland, off-site (6). This means that creation of
one acre of cypress swamp would not be an acceptable replacement
for one acre of Spartina marsh given the weighting system used in
this example.
CONCLUSIONS
Region IV is particularly interested in forested wetland
restoration because of mining activities in the west Kentucky
*
coalfields. Two valuable resources are in direct opposition in
this area: wetlands and coal. The inability to replace forested
wetlands on some disturbed lands has led EPA to seek help in
providing technical guidance to the regulatory and industrial
communities on how to best restore forested wetlands to full
functional capacity. Some of the problems which EPA has
encountered in the coalfields are overburden removal, the swell
factor, restoration of hydrology, and soil reconstruction. A
general problem has been a general lack of detailed, long range
mining plans and conceptual restoration plans by the mining
companies.
There is a need in Region IV for establishment of test plots
to demonstrate that forested wetlands can be restored on various
types of disturbed lands. Replacement mitigation can only be
considered a valid part of the permit process if it is proven to
17
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be possible in test plots. These attempts at replacing forested
wetland areas must be documented to record successful and modify
unsuccessful techniques. The prolonged nature and lack of
monitoring of BLH restoration/creation projects makes the
establishment of functioning forested wetland systems
questionable and regulatory agencies leery of allowing
destruction of naturally functioning wetlands for unproven
mitigation.
Thus, a major reason for this Workshop is to establish the
criteria and performance standards to use in the evaluation of
mitigation test plots and mitigation proposals and to develop
standardized criteria to be used to evaluate the success of
created forested wetlands. In addition, it is hoped that some
needs which are identified at the Workshop can be pursued by the
research community to facilitate forested wetland mitigation.
Finally, this Workshop is a vehicle for development of
communication between regulatory, industry, and research
communities to exchange information on ecological and economic
parameters which must be factored into every permit decision.
Increased information and knowledge will provide greater
understanding of the difficulty and complexity involved in
forested wetland mitigation and may provide for greater agreement
and amicability in the management of the wetland resource.
18
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PART II
WORKSHOP CHARGES
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WORKSHOP CHARGES
No net loss and increases in the quantity and quality of the
nation's wetland resource has been identified by the National
Wetlands Policy Forum as top short and long-term national
priorities (The Conservation Foundation, 1988) . Avoidance
policies of regulatory agencies serve to limit disturbances on
functional forested wetland ecosystems and contribute to the
realization of the no net loss policy. However, this approach
alone will not result in increases in the quality and quantity of
•
forested wetland ecosystems. This goal can only be accomplished
through restoration ecology in conjunction with numerous
subdisciplines. Mitigation can play a key role in the effort.
Replacement of ecosystem structure, particularly the
vegetation component, is currently accomplished by mitigators.
Unresolved is the extent to which desired functional attributes
are achieved in the process of establishing ecosystem structure.
Some functions have been defined for forested wetland ecosystems
under different categories: hydrology, vegetation, wildlife,
soils, fisheries, and ecosystem processes (Roelle, et al., 1987,
Table 1). In the development of mitigation applications, an
accounting of ecosystem processes will be necessary to ensure
functioning forested wetlands are replaced.
20
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Table 1. Some functions of forested wetland ecosystems (Roelle,
et al., 1987c)
HYDROLOGY
1. Flood control (storage and desynchronization).
2. Ground water recharge.
3. Ground water discharge.
VEGETATION
4. Primary productivity.
5. Timber harvest.
WILDLIFE
6. Provision of food, cover, and other life requisites both
on and off site.
7. Recreation associated with wildlife.
SOILS
8. Sediment trapping.
9. Erosion control.
FISHERIES
10. Provision of food, cover, and other life requisites both
on and off site.
11. Recreation associated with fisheries.
ECOSYSTEM PROCESSES
12. Inputs, outputs, and processing of nutrients, and/or
carbon contaminants.
13. Water quality maintenance.
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Charges to Workshop Participants
Workshop participants were given three charges. For the
purposes of addressing Charge I, Workshop participants were
divided into three Workgroups: Vegetation, Soils, and Hydrology.
During consideration of Charges II and III, participants were
redistributed into two additional Workgroups: Water Quality and
Habitat. Consequently, some individuals will appear as
co-authors for more than one Working Group paper.
Charge I: Development of a Site Classification for Forested
Wetland Mitigation Projects
A conceptual framework was developed by which to classify the
attributes of sites to be used for forested wetland mitigation.
Such a framework was requested to facilitate communication
between mitigators, regulatory agencies, and forested wetland
researchers. This classification system was based on the
condition of vegetation, soils, and hydrology on the proposed
forested wetland mitigation site. Each class of disturbance
represents an incremental change in impact to the functions
delivered by forested wetlands. Thus, while the disturbance
class of vegetation, soils, and hydrology was based on measurable
field characteristics, each class also correlates as nearly as
possible to a specific level of functional change to the
ecosystem. A suggested framework was offered by the N.C. State
University Hardwood Research Cooperative for the consideration of
Workshop participants who adopted the concept and refined its
contents during the Charge I phase of the Workshop.
22
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Disturbance classification factors, while indicating the
potential for forested wetland ecosystem establishment, also
directly mesh with current characteristics agreed upon in che
Federal Manual for Identifying and Delineating Jurisdictional
Wetlands (Federal Interagency Committee for Wetland Delineation,
1989). Consequently, adoption of these factors for classification
of mitigation sites will enable regulators and mitigators to more
quickly adapt their current delineation efforts to include
classification of forested wetland mitigation project sites.
Working groups were requested to accept or reject the
suggested classification framework as it related to their
particular working group area and, if rejected, to develop more
appropriate classification divisions. As a minimum, participants
were requested to evaluate the classification with regard to its
relevance to forested wetland function, its field thresholds, its
broad-scale applicability and its ease of use.
Charge II: Development of Performance Standards
Before lists of monitored characteristics could be developed,
definitions of the parameters by which successful forested
wetland mitigation will be measured were needed. The second
charge to Workshop participants was: Develop the basis upon
which a given forested wetland mitigation will be deemed
successful, i.e., define the goals toward which all forested
wetland mitigations should strive. Each Working Group
(Vegetation, Soils, Hydrology, Water Quality, and Habitat)
evaluated this charge as it related to their specific expertise.
-------
Charge III: Development of Monitoring Lists
The condition of the functions on a proposed forested wetland
mitigation site correlates with the complexity of post-mitigation
parameters to be monitored. The third charge to Workshop
participants was to develop sets of measurable field
characteristics for tracking the relative effectiveness of a
mitigation plan. These characteristics represented, as nearly as
possible, indicators of forested wetland developmental progress.
Each set of field measurements was developed for a given
disturbance status found on the pre-mitigation landscape. For
example, pre-project sites with considerable soil disturbances
(Class III) might require more post-mitigation soil
characteristics to be monitored for longer periods than
pre-project sites with less soil disturbances (Class I). In
addition to monitored features for vegetation, soil, and
hydrology, characteristics for habitat and water quality
functions were also developed. The latter two factors were
included in post-project monitoring requirements because, along
with vegetation, they represent measures of ecosystem restoration
success that the ecosystem driving factors of soil and hydrology
can not. Also, it avoided the practical problem of artificially
trying to separate hydrology and water quality.
Participants were requested to base the requirement of each
characteristic and its level of post-project performance upon the
best available information at the time of the Workshop.
Supportive information from refereed journals were given highest
priority in this regard. Nevertheless, owing to the relatively
24
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high level of uncertainty associated with developing success
criteria, this set of characteristics was viewed as a firsc
approximation derived through group consensus; updating will
occur as these levels are verified through research.
25
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PART III
SUMMARIES OF WORKING GROUP
DELIBERATIONS
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1. VEGETATION WORKING GROUP
Andre Clewell (Chair), Russell Lea, William Harms, Clark Ashby,
Russell Theriot, Don Walker, Ronnie Haynes, D. Thompson Tew
(Recorder)
The MiST classification system for vegetation was adopted by
consensus of the working group for use at pre-project forested
wetland mitigation sites. This classification is presented in
Table 1. It is easy to apply and it will characterize a broad
range of project site types for mitigation purposes. The system
quantifies the degree of disturbance for sites, both wetland ana
non-wetland, that are candidates for forested wetland mitigation
projects.
This classification system compares the vegetation on a
proposed mitigation site with that of a reference forest
ecosystem (RFE, see Glossary). Description of the RFE will
require a careful definition for each proposed project. In its
simplest form, the RFE could be a particular wetland or forested
wetland from which exotic and weedy species were ignored in the
floristic inventory. In other cases, the vegetative component of
the RFE could be synthesized from regional ecosystem descriptions
in the literature. In any case, particular care must be taken to
exclude species from the RFE that represent habitat types that
are not targeted for restoration. For example, the RFE should
not include deep tupelo swamp species, if the mitigation site is
to be inundated only briefly each year.
Use of a RFE is chosen in lieu of mandating a specific
"reference wetland" for two reasons: First, virtually all
candidate reference wetlands have suffered at least some
relatively recent disturbance, and forested wetland restoration
27
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Table 1.
MiST Classification for Vegetation.
CLASS
DEFINITION
0 Site has an overstory and understory species
composition and physiognomy similar to the
Reference Forest Ecosystem (RFE-see glossary).
1 Loss, relative to the RFE, of up to 50% of the:
a) tree canopy, and/or
b) canopy tree species composition, and/or
c) undergrowth cover, and/or
d).undergrowth species composition.
2 Loss, relative to the RFE, of more than 50% of the:
a) tree canopy, and/or
b) canopy tree species composition, and/or
c) undergrowth cover, and/or
d) undergrowth species composition.
3 Originally the project site was not sufficiently
populated with hydrophytic vegetation to be delineated
as a wetland or the forested wetland ecosystem
was entirely removed prior to mitigation.
projects generally should not aim at emulating disturbances.
Second, careful study of mature, relatively undisturbed wetlands
often reveals considerable intra-stand variation in species
composition and dominance, owing to subtle habitat differences
and to the play of stochastic events in serai processes (Clewell
and Lea, 1989) . The selection of one reference wetland over
another, therefore, is not justified ecologically. Consequently,
the RFE will provide a more satisfactory target for calibrating
project success.
The distinction between the reference wetland and the RFE
approaches is exemplified in those instances where a reference
wetland is dominated by an undesirable escaped exotic species.
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The mitigation site will usually serve a greater public interest,
if returned to a forested wetland stand lacking that exotic
species.
MiST vegetation classes 1 and 2 are based on the degree cf
loss in both the canopy and the undergrowth in terms of cover and
of species composition, as related to the RFE. Percent cover and
species composition are parameters, which represent the broad
structural components of forested wetland vegetation. Fifty
percent loss (relative to the RFE) is used as a separation poinc
to allow for ease of classification and to facilitate
communication on the degree of disturbance. These classes also
reflect the relative amount of time required for natural
regeneration to rehabilitate a proposed project site.
As an example of how the classification would be applied,
suppose a forest has been disturbed by the selective harvest of
black walnut (Juglans nigra). When compared to a RFE which has a
black walnut component, this vegetational condition would
represent class 1, because it suffered a loss in tree species
composition. Even if some walnut remained standing, the site
would still represent class 1, because of loss of canopy cover.
As another example, suppose an uncut forest has been subjected to
heavy grazing by cattle. This forest would be classified as
class 2 (if loss of undergrowth cover exceeded 50%) or class 1
(if less than 50%). Grazing may have caused a replacement of the
original flora of the undergrowth by weeds. Even though there may
be considerable weedy cover, the site would be classified as
class 2 (not class 1) because of the loss of more than 50% of the
species in the undergrowth, relative to the RFE.
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The addition of class 3 to the MiST classification fcr
vegetation allows for projects that lack on-site propacuie
sources to attain adequate revegetation by species typical of the
RFE.
Charge II: Definition of Performance Standards.
Performance standards describe the minimum thresholds of
acceptable vegetational recovery at mitigation sites.
Performance standards are attained when the mitigated forested
wetland project sites contain:
1) An approved composition of canopy and undergrowth species
typical of the RFE and represented by self-sustaining
populations.
2) An approved tree abundance in terms of density and spatial
distribution throughout the project site.
3) Well established trees, that is, trees that have been
rooted at the mitigation site long enough to survive the
normal gamut of extremes in environmental conditions.
It is incumbent upon those responsible for developing and
approving the restoration plan to determine to what degree, if
any, that natural regeneration will lead to the prompt attainment
of performance standards. Some restoration may be accomplished
passively merely by protecting the project site, so that natural
processes can proceed. Many projects, though, will require
out-p1=nting of nursery stock or other active measures.
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Charge III: Specific MiST Vegetation Performance Standards
The following standards should be attained before the
mitigation project is ready for release from regulatory
liability:
1) A mean density of 400 trees per acre (TPA) are growing at
the project site consisting of preferred, potential canopy
species, which are at least 6 feet tall and which have been
established on site for at least 2 4 months.
2) At least 400 TPA, regardless of height and duration of
establishment, grow on every acre-sized parcel within the project
site.
3) Included among the canopy tree species are certain key
species (dominants, characteristic species, etc., to be approved
in advance), each of which is present at a minimum density of 10
TPA.
4) At least some plants of selected woody and herbaceous
undergrowth species will have been growing at the project site
for at least 12 months prior to project release. The number of
species shall be approved before mitigation activities begin and
will include at least 10 percent of the preferred undergrowth
species of the RFE.
5) Nuisance species will cover less than 10 percent of the
project area at the time of release. To the greatest extent
possible, potential nuisance species should be identified in
advance, and their populations should be controlled at a level
sufficiently low as to be non-threatening to the prompt release
of the project.
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Certain species with characteristically slow growth (e.g.,
cabbage palms, Sabal palmetto) may be allowed to meet the density
standard as long as their terminal buds are elevated above the
soil. This height requirement waiver is subject to the approval
of the regulatory authority.
Exclusions of specific project acreage for determining tree
density may be approved at the discretion of the regulatory
agency, based on (1) non-anthropogenic physical habitat
restrictions (e.g., naturally unproductive habitats, or seasonal
sloughs where tree densities are normally low); (2) forest type
considerations (e.g., cypress rings or cane breaks that normally
have low tree densities); or (3) management considerations (e.g.,
intended future use of the site for wildlife species that require
semi-open forest). Exclusions other than these examples may also
be considered with regulatory authority approval.
Monitoring is required in order to determine whether or not
the restored vegetation at a project site has attained the
requisite levels of performance. Table 2 outlines the kinds of
monitoring needed. The intensity of monitoring is dependent
upon the vegetation class (Table 1), prior to the commencement of
restoration activities.
Assessment methods should be approved prior to the onset of
replacement activities. A report containing monitoring data
should be submitted to the permitting agency immediately
following each assessment.
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Table 2. Monitoring Required for MiST Vegetation Performance
Standards Assessment.
TREE CRITERIA:
400 TPA overall 6+ feet tall, 400 TPA on every acre,
and approved species present at 10 TPA.
CLASS 1: Determine if all criteria are met at the end
of the 2nd year. (Assumes no tree planting
was necessary.)
CLASS 2: a) Initially, assess potential for natural
recovery. If adequate potential, determine if all
criteria are met at the end of the 2nd year. If
inadequate potential, then prepare & implement
plan for tree planting.
b) Oversee tree planting, if any.
c) If trees were planted, determine their
survival following the first growing season.
d) If trees were planted, determine their
species densities and heights following
subsequent growing seasons.
CLASS 3: a) Oversee tree planting.
b) Determine planted tree survival following
the first growing season.
c) Determine planted tree species densities
and heights following subsequent growing
seasons.
UNDERGROWTH AND NUISANCE SPECIES CRITERIA:
10% of RFE represented, and <10% nuisance species present.
CLASS 1: Determine if undergrowth and nuisance species
criteria were met after the 2nd year using
approved sampling methods.
CLASS 2: Prepare lists of all preferred undergrowth
species and all nuisance species annually
on a per acre basis using approved sampling
methods.
CLASS 3: Prepare lists of all preferred undergrowth
species and all nuisance species annually
on a per acre basis using approved sampling
methods.
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2. SOILS WORKING GROUP
Jack Nawrot (Chair), Ellis Clairain, David Cobb, Wayne Davis,
Jeff Furness, Charles Hooks, Glenn Kelley, Steve Mader,
Jim Sandusky, Thomas Welborn, Dennis Mengel (Recorder)
The goal of the Soils Working Group was to recognize the
value of mitigation guidelines, but to avoid the regulatory
pitfalls of site-specific performance criteria. The MiST Soil
classification treats the soil as a physical substrate for
establishment of the desired forested wetland type. MiST soil
classifications emphasize physical disruptions of the soil
profile that can adversely affect the ability of the proposed
mitigation site to support the desired forested wetland type or
RFE. The proposed soil condition classification system does not
emphasize macro- or micronutrient conditions, or short-term
organic matter (litter layer) development processes. These
conditions and processes are site-specific or dependent on
natural, short-term disturbances and, thus, not appropriate for a
Region-wide classification system.
Table 1 presents the MiST classification system for project
site soils. There are four classes ranging from sites free of
anthropogenic disturbance (Class 0) to complete disruption of the
original soil (Class 4). Increasing class level implies a higher
degree of difficulty in mitigating the site, i.e., Class 4 will
require more inputs than Class 2.
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Table 1. MiST Soil classification system.
CLASS CONDITION
0 Soils are undisturbed by other than natural means.
1 Disturbance limited to the top 12 inches of the soil1
(e.g., clearing, plowing, significant changes to
site hydrology) and/or loss of up to 50% of the top
12 inches of the existing soil.
2 1) Disturbance within the top 12 inches with loss of
greater than 50% of the top 12 inches of the existing
soil, AND/OR, 2) Compaction that has been identified
affecting the rooting zone at a degree greater than the
reference soil. The significance of the size of area
affected should be determined on an on-site basis.
3 Reconstructed soil (e.g., mining - soil horizon
replacement).
4 1) Loss of soil profile to a depth greater than 12
inches, OR, 2) Loss of the original subsoil structure,
OR, 3) new soils developed from materials other than
original mineral soil. -
Twelve inches was chosen because the majority of the root
related activity in forested ecosystems occurs in the top 12
inches of the soil surface.
Charge II: Development of Success Criteria
The following statement defines successful soil mitigation of
the site:
A soil will be considered acceptable from a restoration
viewpoint if it has the physical and chemical properties that
are necessary for the successful re-establishment of the
desired reference forest e'cosystem. At a minimum, the soil
will contain hydric characteristics as listed in the
definitions of the Federal Wetland Delineation Manual (1989).
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The intent of the above statement is to define what needs co
be accomplished, not how to accomplish it.
Two sites will be involved in the mitigation project, the RFE
and the proposed mitigation site. These two areas may be at cr.e
same (on-site mitigation) or separate (off-site mitigation)
locations.
The RFE will be characterized to obtain baseline data of the
undisturbed soil condition. These baseline data will be used as
the criteria against which the restored soil will be compared.
Monitoring the mitigation site will take place in two phases,
an initial and a restoration / reclamation phase. The initial
phase will establish a baseline characterization of the project
site landscape prior to forested wetland mitigation. Soil
physical and chemical conditions deemed necessary for successful
vegetation establishment will be measured and physical or
chemical conditions (e.g., toxicity), that require amelioration
will be identified. The restoration / reclamation phase will
consist of annual monitoring to document short-term trends and
indication of long-term success.
Charge III: MiST Soil Success Parameters
To achieve the above objectives, specific variables need to
be measured in the monitoring process. Table 2 presents the
minimum set of variables that need to be measured on the RFE and
mitigation r^tes. The measurements are divided into two groups:
physical and chemical. The chemical group is further divided
into potential phytotoxic/micronutrients and macronutrients
subgroups. Each group or subgroup is designated by a letter code
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Table 2. Chemical and physical factors to be measured on che
reference and mitigation sites.
FACTOR VARIABLES
Phvs ical
A Saturated hydraulic conductivity, texture
(to assess the ability to establish hydric soil
conditions)
Chemical
B Potential phytotoxic/micronutrient conditions
pH, pyritic sulphur, neutralization potential, Al, Cu,
Zn, B, Mn, base saturation, conductivity, redox
potential
C Macronutrients
N, P, K, organic C
in the Tables. Table 3 relates these codes to the frequency of
measurement on each site by Mi ST soil class. Table 3 also
indicates the depth of measurement of each group of variables on
each site. Physical factors (Factor A) are measured as needed in
the restoration/reclamation phase, because they are not likely to
change over the length of the project. Only those physical
factors that have been ameliorated during the restoration process
will need monitoring to determine the success of the mitigation.
The intensity at which the sites are to be sampled will be
based on the size of the project and the inherent heterogeneity
of the specific soil-site conditions. The number of samples
needed for each variable will be determined through consultation
with the regulatory authority and/or soil science experts
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Table 3. Measurement schedule of factors by disturbance class
on the reference and mitigation sites.
MiST SOIL CLASSES
II III IV
BASELINE REFERENCE ABC1
FACTORS
INITIAL SITE ?
CHARACTERIZATION ABC ABC ABC ABC
RESTORATION /_ < A as needed >
RECLAMATION < B C > < B C >
(min. 2 years) (min. 5 years)
These only apply to the reference forest ecosystem
(Class 0). Factor A measured in rooting zone; B and
C factors measured at 0 - 9 inches depth.
2
Factor A to be measured in the rooting zone as
defined from the reference site. Factors B and C to
be measured at:
Class I, II - 0 -9 inches;
Class III - by horizon;
Class IV - by horizons or depth as determined by
backfill placement technique)
3
All factors measured as defined in 2 above on an
annual basis.
conversant in hydric soils and their relationship to wetland
vegetation and hydrologic characteristics.
The developed list is not exhaustive. Variables not
identified in this document may be encountered and considered
important on a site by si-e basis. Therefore, this list
represents the minimum set of variables that need to be measured
on a given site. Note that field and/or laboratory methodologies
are not listed in this document in order to allow for regional
38
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differences in methodologies to obtain these data. However,
regardless of the procedures employed for measurement, the same
methods should be used when measuring specific variables on the
reference and mitigation sites. For example, if pH is measured
using a 1:1 soil to water ratio on the reference site, the pH
should be determined on the mitigation site using the same racio.
Detailed procedures for assessing chemical and physical
parameters can be found in Page et al. (1982) and Klute (1986).
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3. HYDROLOGY WORKING GROUP
Wade Nutter (Chair), William Ainslie, Phil O'Dell, Mark Brinson,
Charles Belin, William Kruczynski, Delbert Hicks, James Allen,
Donna Perison (Recorder)
Introduction
The hydrology present on a mitigation project site is the
driving force of the wetland system. Hydrology is defined as
the presence of hydrologic factors such as frequency, duration,
seasonality, and source of inundation and/or soil saturation that
result in the maintenance of a reference forest ecosystem (RFE).
The hydrologic condition present on any site will dictate what
type of plant community can be supported. The fact that specific
hydrologic regimes are associated with different reference
ecosystems, makes it necessary to integrate the evaluation of
hydrologic mitigation success with the type of reference forest
ecosystem that is desired.
Of the aforementioned hydrologic factors, source of
inundation and/or saturation and seasonality of inundation and/or
soil saturation are unique to specific RFEs. A project site with
hydrologic conditions of equal magnitude to the RFE will be
ranked as a Class 0 disturbance. If source and seasonality are
not intact, a site will be ranked in the highest disturbance
class (Class IV). Intermediate classes of hydrologic condition
are determined by deviations in frequency and duration from the
RFE with no departure in the crucial hydrologic factors of source
and seasonality. (Table 1). For example, a mitigation site will
be given a Class I disturbance if a 4 month period of inundation
during the dormant season on the RFE is 3 months during the
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Table 1. MiST Classification System for Hydrology
CLASS DISTURBANCE
Class 0 Undisturbed hydrology based on comparison with
hydrologic conditions in the RFE.
Class I A deviation in frequency and duration
hydrologic conditions not greater than 25% of
the RFE.
Class II A deviation in frequency and duration of
hydrologic conditions not greater than 50% of
the RFE. The dominant season and source of
inundation do not deviate from the RFE.
Class III A deviation in frequency and duration of inundation
greater than 50% of the RFE. The dominant season
and source of inundation do not deviate from
the RFE.
Class IV A deviation in frequency and duration of inundation
greater than 50% of the RFE AND the dominant season
and source of inundation deviate from the RFE.
dormant season on the mitigation site. This would represent
a deviation in a principal hydrologic condition not greater than
25% of the RFE.
Charge II: Development of Success Criteria
Both in-kind and out-of-kind mitigation efforts will be aimed
at obtaining the RFE hydrologic conditions dictated in Class 0
which emphasizes the establishment of proper seasonality and
source. In addition, if the vegetative, soil, and water quality
conditions for success are satisfied within Class I hydrology
criteria, hydrologic conditions will be considered to have been
restored within the bounds of successful mitigation. The chosen
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RFE is also assumed to fall within the bounds of a jurisdictional
wetland.
The time required to produce a successful nydroiocic
condition is dictated in most cases by achievement of me
vegetation and water quality success criteria. It is expected
that between two and five years of normal climatic and hydrologic
conditions may be needed to create conditions for judging
success.
Charge III: Mist Hydrologic Perfomance Standards
A number of basic recommendations can be made with regard to
the assessment of hydrologic success parameters. These include:
1) Because soil physical properties are important to
maintenance of hydrologic conditions, those soil
properties must be created/restored.
2) A techniques manual should be prepared describing
fundamental methodologies for measuring/observing
conditions for judging success.
3) Mitigation processes should not result in an
adverse impact to the water resource (e.g., aquatic
habitat in river)
Minimum monitoring by disturbance class
Tables 2 and 3 establish the minimum monitoring schedules for
the hydrologic parameters of frequency, duration, seasonality and
source of inundation. These schedules assume that a RFE is
paired with the proposed mitigation site in a manner similar to a
paired catchment.
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Table 2.
Measurements required for MiST Hydrology Performance
Standards.
CLASS
MONITORED PARAMETERS
0
No monitoring is required.
I
Frequency and Duration
1) Semi-annual visual observation of site
during dormant and early part of growing
season
2) Follow-up visits to determine duration
plus visual observation of drift lines,
sediment on leaves, silt lines on
trees, etc.
II
Frequency and Duration
Quarterly monitoring visits coupled
with a continuous recording device
(combination piezometer/crest gage)
with a frequency of recording not
greater than seven days; couple recorded .
data with visual observations.
III
Frequency and Duration
Monthly monitoring visits coupled
with a continuous recording device.
IV
Frequency and Duration
Same as Class III
Seasonality and Source
1) Same as Class III
When local stream gaging data (e.g., USGS) are available and
correlation of the gaging data can be made with at least one year
of reference and mitigation site monitoring data, gaging station
data may be substituted for on-site monitoring.
In addition to the above requirements for hydrologic
monitoring, other considerations are:
1) Frequency of monitoring to determine depth of flooding or
drawdown may be modified on a case by case basis dependent on the
type of RFE to be mitigated (e.g., some forested wetlands have
43
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Table 3. Frequency of monitoring of MiST Hydrologic
Performance Standards
MiST HYDROLOGY CLASS
I II III
SUCCESS CRITERION
Frequency
Duration
Seasonality
Source
SA
SA
/
/
Q
Q
/
/
M
M
/
/
M
M
M
/ - Not required
M - Monthly
Q - Quarterly
SA - 2 times/year
less variation in frequency and duration of flooding than
others).
2) A minimum of one monitoring station is required. However,
recognizing that instruments may fail or can be vandalized, at
least two stations are recommended and must be strategically
placed to represent the entire mitigated forested wetland when
compared with the RFE.
3) A strong correlation of conditions at the mitigated site
with the reference site shown early in the project may allow for
the reduction in the frequency of monitoring if the establishment
of vegetation and soils is progressing as planned. This
determination should be made in conjunction with regulatory
authorities.
44
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The above plan represents the minimum instrumentation ar.c
sampling frequency to monitor mitigation. Additional
instrumentation may be necessary to completely characterize ~r.e
site. This may include several piezometers for manual
measurements during site visits, a piezometer nest to determine
vertical groundwater movement, and crest stage gauges to further
characterize inundation across the site.
45
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4. WATER QUALITY WORKING GROUP
Mark Brinson (Chair), William Kruczynski, Delbert Hicks, Don
Walker, Charles Belin, Stephen Mader (Recorder)
Charge II: Develop the definition of success relative to
RFE characteristics
Criteria for judging the successful achievement of acceptable
water quality following mitigation are the same for all MiST
classes (Hydrology, Soils, Vegetation). In practice, the more
degraded the site, the longer is the expected time to achieve
success. However, there is no a priori reason to alter the water
quality parameters as a function of initial site condition.
Monitoring of the RFE and the constructed or restored site should
be approached as a paired watershed experiment. The RFE wili
serve as the control for establishing the levels and variability
of target thresholds while the constructed/restored site will
serve as the experimental treatment. Successful restoration is
achieved when levels of water quality parameters approach those
of the RFE. Minimally, levels should not violate state water
quality (401) standards. When applicable, state-established
variances for certain wetlands and classes of naturally-deviating
surface waters should be accommodated during evaluation.
The permittee may choose to select more than one RFE, using
average water quality values as goals. This is recommended if
there is a possibility that background conditions (i.e., quality
of source waters to the wetland) may change sianificantly within
the 5-year evaluation period due to alterations in land use,
point source discharges, or water flow. Also, the wide variation
among natural ecosystems and the inexperience of most
46
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practitioners in recognizing realistic RFEs further argue f::
multiple reference sites.
Performance standards will be achieved when, for each wacer
quality parameter, comparisons of the distributions of sampled
data between the mitigation site and FIFE overlap by a certain
percentage. Both the methodology to determine the overlap and
the percentage of overlap are to be approved by the regulatory
agency. Importantly, approved overlap percentages may vary among
water quality parameters.
One example of methodology is the graphical analysis of
paired histograms (Figures 1 and 2). Another approach is to
calculate of means and standard deviations and applying
appropriate statistical tests. All water quality parameters must
meet its particular performance standard for the mitigation to be
successful. However, it is paramount to recognize that sampling
and methodological errors may preclude achieving high overlap in
some cases. This should be considered by the mitigator and
regulatory agency during the determination of appropriate overlap
percentages.
Charge III: Develop a list of monitored characteristics
within each level of project site condition.
Monitored characteristics were chosen for:
1) Simplicity: the list is short and methods of collection
are straightforward.
2) Familiarity: standard procedures are available that can
meet quality assurances.
47
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Figure 1. Successful restoration of water
quality parameter.
PERCENT OF SAMPLES
PARAMETER CLASS
Frequency distribution of parameter
for constructed/restored site overlaps
>90% of reference wetland distribution.
3) Information: the parameters provide insight into
ecosystem function.
4) Cost: in large measure, these methodologies are fairly
inexpensive.
The list of water quality parameters to be monitored
following the execution of a mitigation plan is presented below
with a brief rationale for each. Hem (1985) has provided more
detailed descriptions. The types of analyses for monitoring
water quality are shown in Table 1.
1) Temperature: This is needed for expressing dissolved
oxygen as percent saturation.
2) Acidity, alkalinity, and electrical conductivity (surface
water): These environmental properties are important to aquatic
48
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Figure 2. Failed restoration of water quality
parameter.
PERCENT OF SAMPLES
100
80 -
WETLAND STATUS
Constructed/restored Reference wetland
60 -
PARAMETER CLASS
Frequency distribution of parameter for
constructed/restored site overlaps <90%
of reference wetland distribution.
organisms and bi'ogeochemical processes. For example, many
organisms have optimal ranges of pH values. Chemical equilibria
that control the availability of phosphorus, other essential
nutrients, and potentially toxic metals are pH dependent.
Alkalinity is closely associated with pH because it is an index
of the buffering capacity of water to resist change in pH.
Conductivity is a robust index of total ion activity and total
dissolved solids. Fresh water of high conductivity is less
likely to create nutrient limitations to aquatic primary
productivity than water of very low conductivity. Conductivity
and alkalinity may be strongly correlated when calcium is the
dominant cation. Depending on lithology of the area,
49
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Table 1. Monitoring of Water Quality Parameters.
, 2 Surface Ground
Analyses ' water water
Field: Temperature"^ X
Acidity X X
Conductivity X X
Dissolved oxygen^ X
Redox potential (Eh) X4
Lab: Alkalinity X X
Suspended solids X
TOC\
TOC/TON X
TON/
"'"EPA quality assurance is implied. These are the minimum
required; additional analyses may be added for special
cases such as sites formerly occupied by mines, industry,
or other intensive land-uses.
2
The ecosystem parameters listed in this table are to be
monitored for all MiST Classes. In the unique situation-
where a MiST Soils Classification III is determined,
additional parameters judged appropriate may be added to
this list of mandatory characteristics for ground water
and surface water monitoring (i.e., former mine sites).
3
Paired sites should be measured at nearly the same time of
day because of anticipated diel functions.
4
Precautions should be taken to assure that in situ values
are not altered in the process of measurement.
50
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conductivity may indicate the source of water masses, thus aiding
in the interpretation of hydrologic functions. In cases where it
is critical to know sources of water and their relative
contributions, analysis of major cations and anions may be
necessary.
3) Suspended solids: Suspended solids are usually derived
from erosive surfaces. The amount should indicate the extent to
which the wetland functions as a depositional environment ana
reduces suspended solids. High levels of suspended solids may be
due to either a persistent source outside the system or an
unstable depositional environment within the wetland.
4) TOC: Total organic carbon reflects the organic richness of
the system. Watersheds with abundant wetlands and organic soils
normally yield higher concentrations of TOC than those which are
sparse in wetlands (Mulholland and Kuenzler 1979). Humic
compounds are the major organic constituents of darkly stained
waters whereas plankton production is the dominant source of
organic compounds in clear waters.
5) TON: Total organic nitrogen can be used in conjunction
with TOC to provide C/N ratios; such ratios in water exported
from wetlands are high in "black-water" and low in water that
lacks the organic staining. Wetlands that accumulate organic
carbon in soils due to reducing conditions may vary greatly in
absolute concentrations of TOC and TON, but the ratio between the
two tends to normalize the indices by removing variation due to
dilution and concentration effects.
6) Acidity, alkalinity, and electrical conductivity (ground
water): The groundwater measurements of pH, alkalinity, and
-------
conductivity yield essentially the same type of information as
for surface water. The values may reflect soil chemical
properties relevant to suitability for soil organisms and plane
lif e.
7) Redox potential (Eh): Redox potential estimates the
reducing status of soils/sediments on a scale that extends beyond
the depletion of oxygen. It indicates the extent to which
anaerobic respiration has taken place and, like pH, provides
insight into the abundance, form, and activity of elements such
as inorganic nitrogen, iron, sulfur, and heavy metals (Stumm and
Morgan 1981).
Procedures for Sampling Water Quality Characteristics
The recommendations given below should be considered
guidelines that may need to be modified extensively according to
size, location, and other site-specific conditions. They are
summarized below:
1. Number of samples.
a. Minimally, sets of samples of surface water and ground
water will be taken on a monthly basis for two years.
Thus, at least 24 sets of samples will be obtained from
the mitigation site and 24 sets will be taken
simultaneously from the RFE. These data will be used in
frequency analyses.
b. If surface water is not present on either the reference
ecosystem or experimental site at all desired monthly
sampling times, samples will be taken until 24 surface
water samples are collected. In this instance, sampling
52
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intervals will occur no shorter than monthly. If 24
samples have not been obtained within 5 years after zhe
initiation of monitoring, a determination of success is
based on the completed measurements. In this case, a
trend analysis rather than frequency analysis might be
more applicable.
2. Peak flows.
Samples must include at least 4 peak flows. Peak flows
are defined as maximum flow that occurs during a given
stormflow event, usually expressed as cubic feet per
second (cfs).
3. Sampling design.
The sampling design will be sufficiently rigorous to
characterize the reference and constructed/restored sites
and physiographic heterogeniety within them (e.g.,
sloughs, flats, channels, discrete wetland types).
Physiography affects the quality of exported water so that
it may be necessary to arrange the analysis of results
according to physiographic type.
4. Connectivity among sites.
If a series of constructed/restored sites is connected,
each site should be monitored separately. It should be
noted that if hydrologic connectivity among sites is high,
water quality values among sites are likely to be
correlated. Consequently, this covariance could detract
from the usefulness of related water quality performance
standards of specific traits.
53
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5. HABITAT WORKING GROUP
Ronnie Haynes (Chair), Wayne Davis, Ellis Clairain, Bob Bay,
Jim Sandusky, James Allen (Recorder)
Charges II and III: Develop the definition of success relative tc
the reference ecosystem characteristics and develop a list of
monitored characteristics within each MiST class.
Previous workshops dealt with the impacts of various
activities and the assessment of functions associated with
bottomland forest ecosystems (Forsythe, et al. 1987a - c). These
workshops addressed the identification of criteria believed to be
useful in evaluating the recovery of these ecosystems from a
wildlife perspective and provided a basis for discussions within
the present habitat working group.
Several conclusions can be reached about the identification
and monitoring of criteria for determining the success of
restoration of habitat factors associated with the establishment
of freshwater forested wetland communities:
1) For activities that could result in a major loss of the
freshwater forested wetland community (e.g., MiST classification
II for vegetation or classes III or IV for hydrology), the
selection and use of meaningful criteria for measuring and
evaluating the performance of replaced habitat factors for
species that reside in or use the ecosystem type are unclear
given the typical regulatory time frames associated with
permitting disturbance activities.
This conclusion was based on the fact that replacement of a
mature freshwater forested wetland community, with functions and
values similar to those that occurred prior to disturbance,
requires a lengthy period of time. The time period required for
54
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this replacement will be influenced by many environmental factors
including growth media and hydrologic conditions. Yet,
regulatory permit requirements are usually specified for a period
of only a few years to possibly 10 years in special demonstration
cases.
2) Successful implementation of the specific mitigation
measures for replacing vegetation, soils, and hydrology (as
detailed in the working group reports herein) should provide
reasonable and acceptable assurance that a freshwater forested
wetland community similar to that which existed prior to
disturbance will occur given sufficient time.
Natural regeneration produces a succession of community types
over time leading to a freshwater forested wetland community.
Given no intervention, the type of community eventually replaced
will depend upon time, hydrologic, edaphic, and other
environmental factors. Wildlife species being opportunistic, are
expected to use the various habitat types over time according to
their life needs (i.e., food, cover, water, etc.).
At the time when the replacement forest community resembles
the habitat components found in the pre-disturbance or RFE, the
wildlife species that reside in or use the replacement forest
should correspond, unless habitat isolation problems or other
unrecognized limiting factors exist.
Compensation measures
Although the habitat working group does not recommend
monitoring of specific habitat factors for evaluating successful
replacement of damaged freshwater forested wetland ecosystems
within a short-term monitoring plan (i.e., 2-10 years),
55
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monitoring of key habitat factors for selected species of special
interest is recommended as a compensation measure.
Compensation of habitat components lost as a result of major
disturbance activities (i.e., MiST class II for vegetation or
hydrology MiST class III or IV) is recommended because of the
risk that a given forested wetland mitigation may not adequately
achieve the performance standards set forth in this document and
the potential lack of regulatory accountability given such a
event.
Selected compensation measures should be developed and
integrated into the mitigation plan in consultation with the
state fish and wildlife agency and the U.S. Fish and Wildlife
m
Service. The mitigation plan would address the reduction or
elimination of limiting habitat factors that would occur as a
result of the disturbance by 1) identifying the specific species
or groups of species compensated for during the regulatory permit
period and; 2) listing the specific habitat compensations needed
based on the known life needs of the evaluation species.
Examples of potential compensation measures to benefit fish
and wildlife are noted in Table 1. It should be noted that this
list is not exhaustive. The need for compensatory wildlife
measures must be project specific. Thus, some mitigations may
not require any of these compensations while others would need
all of them and more for the mitigation plan to be acceptable.
Habitat mitigation and monitoring will consist of three
phases, two of which are required and one optional (Table 2).
Identification of endangered species, preparation of species
lists, etc., (i.e., most of Phase I) will often be components of
56
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Table 1. Potential mitigation measures to benefit fish and
wildlife during replacement of freshwater forested
wetland ecosystems.
1. Installation and maintenance of wood duck nest boxes (Marcy
1986/ Mitchell 1988).
2. Building and managing moist-soil areas for waterfowl and other
species (Fredrickson and Taylor 1982).
3. Establishment of small food plots within forest areas.
4. Leaving dead snags and large trees with cavities whenever
possible.
5. Leaving buffer zones along streams whenever possible.
6. Selective thinning to promote new vegetation growth.
7. Establishing brush piles for cover (Martin and Steele 1986).
8. Establishing a source of permanent water if none exists
(Martin and Marcy 1989).
9. Establishing vegetative corridors between existing and
replaced freshwater forested tracts.
10.Ensuring interspersion of habitat types over the total
project area.
Other potential references include Mitchell and Newling (1986)
and Teaford (1986) .
the initial, pre-mitigation permit application process.
Nevertheless, their identification will assist in developing
compensation measures if the proposed disturbance is approved.
Compensation measures, when needed, will be prepared according to
the results of the Phase I analysis.
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Table 2. Habitat Mitigation Phases
PHASE I - RFE1 / PROPOSED IMPACT SITE ANALYSIS
A. Determine if endangered/threatened species are present.
B. Develop species lists.
C. Select evaluation species based on perceived importance,
indicator status, etc.
C. Evaluate habitat quality for selected species.
D. Determine relationship of reference site to surrounding
landscape (interspersion among other habitat types, total
area of reference type, etc.)
PHASE II - MONITORING DURING PERMIT REGULATORY PERIOD
(Assumed to be up to 5 years, with maximum of 10)
A. Use MiST soils, hydrologic, and vegetation monitoring
criteria as acceptable measures of long-term habitat
mitigation success; assumes acceptable values for most
species will be met.
B. For MiST Class II Vegetation and classes III or IV ^
Hydrology, calculate habitat suitability index values of
selected evaluation species and community characteristics
known to be important to wildlife (e.g., size of area,
interspersion factors) during the following periods:
1) One year after mitigation plan is implemented.
2) Midway through regulatory period.
3) Immediately prior to regulatory release.
C. For MiST Class II Vegetation and Classes III or IV
Hydrology, ensure that short term habitat improvement
practices were implemented (See Table 1).
PHASE III - LONG-TERM MONITORING (optional)
A. Follow-up study by management entity (to be identified
in mitigation plan) to compare baseline values with
post mitigation values with goal of replacement of
habitat type(s) and associated values.
2 RFE = Reference Forest Ecosystem (see glossary).
See Schamberger et al. (1982) .
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PART IV
USE OF MiST IN THE FIELD
AND
SELECTION OF A REFERENCE FOREST ECOSYSTEM
-------
USING MiST IN THE FIELD: SUGGESTIONS AND KEY TO THE
MiST CLASSIFICATION
T.A. White
Introduction
Information contained in this document can result in a
significant contribution to the development of useful and high
performance replacement forested wetlands. The purpose of this
section is to transfer the information contained in the
preceding tables and text into a format that can be immediately
applicable in a variety of field situations.
A number of approaches can and will be developed to execute
the MiST classification system. So although this section
provides guidance in the use of MiST, it does not suggest that
this is the exclusive manner in which to utilize the system.
Instead, it relates current field testing considerations in a
manner that, hopefully, will obviate some potential difficulties.
As MiST continues to be field-tested, new and more appropriate
approaches will certainly be developed.
Moreover, the variability of environmental and
project-related factors renders much of the MiST system as
negotiable between the mitigator and the regulatory authority.
For example, the percentage of acceptable overlap of a mitigation
site water quality parameter with its counterpart from the RFE
may vary depending upon the importance that the contribution of
given mitigation site has upon the water quality of its
particular watershed. This determination can only be done on a
case by case basis in conjunction with regulatory authorities.
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Approximately 100 different combinations of vegetation, soils
and hydrology could technically exist on the landscape. In
practice, however, a number of them will probably not oe
encountered. This is because degradation of one parameter very
often occurs in conjunction with degradation of another. For
example, it is difficult to imagine total reconstruction of a
soil (S4) without simultaneous total loss of forest cover (V3).
Thus, S4-V0 or S4-V1 combinations are rather unlikely. Similar
situations reduce the possible number of classification
combinations.
Timing of MiST classification
Every MiST attribute should be given the highest class
possible for a given mitigation project to ensure that an
adequate level of monitoring intensity occurs following the
execution of the mitigation plan. Consequently, timing of the
Mi'ST classification is extremely important and can depend upon
the project, the attribute, and the permitted activity. In many
cases, classification can be accomplished using currently
existing site conditions. However, in certain situations,
classifying the attribute on the basis of what will occur either
during or after the conduct of the mitigation or as a result of
the permitted activity may be desirable. For example, current
soil conditions on a mitigation site may yield a classification
of SI. Yet, if the mitigation plan dictates soil disruptions
significant enough to yield a S3 or S4 classification, the soils
should be classified at the higher level (i.e., S3 or S4).
61
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On a given project, MiST classification timing may vary with
the attribute. For example, one can invoke MiST classification
of vegetation, soils, and hydrology simultaneously on ar.
abandoned, previously forested wetland soybean field. In this
case, the soybean field is at the point of greatest disturbance
simultaneously for all three attributes and MiST classification
is straightforward. Alternatively, suppose a mitigation plan
calls for a wetland creation where lowering of site elevations is
proposed with a consequent change in hydrologic conditions. In
this project, soil and vegetative MiST classification would occur
following the elevational manipulation. Yet, hydrologic MiST
classification must occur before the site is carved down as it is
at this point in time that the site's hydrologic conditions
deviate the most from the RFE.
It is not always necessary to classify MiST at the exact
point in time when attribute degradation is at its greatest,
i.e., it is possible to predict the classification of an
attribute in certain circumstances. This is particularly true in
cases where the attribute is given the highest class. When the
mitigator wishes to "pre-classify" the site at a classification
level less than maximum, it is advisable that the mitigator do so
only with the knowledge and endorsement of the regulatory
authority.
HOW TO DETERMINE CLASSIFICATION LEVEL
Selecting the Reference Forest Ecosystem
Selection of a RFE to compare functionality and original site
condition is one of the first tasks of the forest wetland
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mitigator. Choosing an appropriate RFE can be an easy or complex
task depending on a number of factors. These factors are
outlined and discussed in a separate section of this document.
The RFE should be thoroughly characterized with regard co
vegetation, soils, and hydrology. In many cases, comparison of
the mitigation site with the RFE will be necessary to obtain the
appropriate MiST classification. Characterization procedures can
be found in the Wetlands Delineation Manual (1989) and other
publications listed at the end of this document.
Classifying forested wetland attributes
Classification of forested wetland attributes with MiST
involves consideration of any of a number of potential
disturbances. Site conditions need to be thoroughly studied
before attempting to classify the site. Once the disturbances
are understood, users of MiST can refer to the Key to MiST at the
end of this section. Some approaches to analyzing site
conditions follow.
Vegetation
Where V2 or V3 classifications are anticipated, determine
whether the site is a jurisdictional wetland.
Where VO and VI classifications are expected:
a. Select an agency-approved RFE. Determine overstory and
understory composition and cover through approved
sampling methods.
b. Sample existing mitigation site to determine:
1. Overstory cover (can be represented by percent
cover and/or basal area)
2. Overstory species composition
3. Understory cover (percent cover)
4. Understory species composition
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Soils
On sites that are not jurisdictional wetlands or where soils
will be removed and replaced, an S3 or S4 classification is
assumed. No further activities are required for classificaciop.
except to outline soil reconstruction procedures if an S3
classification is desired.
Classification of soils under other circumstances can vary in
complexity. During the determination of soil classification, it
is important to consider all potential disturbances and recognize
that disturbance can be represented by physical and/or chemical
disruptions. These disturbances may be obvious or more subtle.
Nevertheless, both types can greatly affect the ability of the
site to support desired communities. For example, erosion losses
may be obvious and result in an SI classification for the site.
In contrast, a site with significant changes to frequency and
duration of flooding may not show physical disruptions, but have
significant changes to redox potential manifesting in an- SI
classification. Note that change in and by itself should not be
used as a criterion. Only changes that could result in shifts of
species composition, productivity, or habitat degradation away
from the desired ecosystem should be considered.
1. Types of Disturbance:
i. Erosion
Ideally, one evaluates soil erosion losses through comparison
with adjacent, uneroded soils of the same series where possible.
Examination of soil survey maps and field reconnaissance can
assist in identifying areas of similar soils. Preferably, any
64
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comparison of horizon thicknesses should be done as close to the
mitigation site as possible since considerable variation ir.
horizon thicknesses as well as other soil properties can exist
within a given soil series.
In the absence of similar comparatively undisturbed soils in
the immediate area of the mitigation, erosion can be assessed by
evaluation of mitigation site soil profile horizon thicknesses in
comparison with type-profiles described in SCS soil surveys for
the soil series under scrutiny. It is strongly recommended than
this be done with caution and under the scrutiny of a soil
scientist familiar with hydric soils and their properties for the
region of the mitigation site.
ii. Compaction
Physical impediments to root growth and soil water movement
can adversely affect site productivity for extended periods of
time. Numerous approaches exist to estimate compaction. Use of
bulk density rings, penetrometers, etc. can all provide relative
estimates of compaction. However, determination of saturated
hydraulic conductivity provides useful integrative soil physical
data. Saturated hydraulic conductivity is related to factors
influenced by water movement in the soil such as soil redox
potential, acidity, oxygen percent, and total N in the soil water
(Aust et al. 1989). Moreover, net production of woody plants was
shown to vary directly with saturated hydraulic conductivity in
one forested wetland study (Mader et al. 1989). In addition,
this parameter has the added advantage of relative ease of
determination. For these reasons, determination of saturated
-------
hydraulic conductivity is recommended over bulk density and soil
strength estimates. Amoozegar and Warrick (1986) provides field
methodologies for this parameter.
iii. Chemical changes
Addition of toxic materials, significant shifts in redox
potential, significant increases in acidity or alkalinity,
significant losses of macronutrients or potentially deficient
micronutrients, addition of materials that inhibit exchange of
gases and liquids between the soil atmosphere interface, etc.
Methods for assessing chemical levels in soils and, thus,
contribute to the determination of chemical disturbance can be
found in Page et al. (1982).
iv. Loss of litter layer integrity.
Forested wetland ecosystems, as well as other forested
ecosystems are characterized by the development of a distinct
layer of leaves, branches and other debris. This debris serves as
a storehouse of nutrients, organic matter and microflora that
contribute significantly to the productivity of the forest
community. Absence of the litter layer is easily assessed by
comparison with the RFE. Both litter layer thickness and areal
extent should be considered.
Hydrology
Hydrologic deviation of the mitigation site from the RFE is
the criterion used to classify this attribute. Departure in
frequency and duration mark the delineation of the MiST hydrology
6 6
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classes 1, 2 and 3. Class 4 couples deviation of frequency and
duration with deviation in seasonality and source of inur.daticn
waters.
Generally, it is easier to determine large deviations in
hydrologic parameters from the RFE than small variations. This
is particularly true when mitigation sites vary in water source.
In cases where variation of the mitigation site from the RFE is
expected to be small, the mitigator must obtain hydrologic daca
from both sites to evaluate. Some stream channels have been
historically monitored by organizations such as U.S. Geological
Survey. Several other potential sources of historical hydrologic
information are listed in the Federal Manual for Identifying anfl
Delineating Jurisdictional Wetlands. Use of this information in
conjunction with USGS topographic or on-site survey maps can
assist in determining hydrologic deviations between the two
sites. In the absence of historical hydrologic data, selection
of methodology to determine' deviation of the mitigation site
should be done in conjunction with the regulatory agencies.
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KEY TO THE USE OF THE MITIGATION SITE TYPE CLASSIFICATION SYSTEM
(MiST)
Key to MiST Vegetation
Key to MiST Soils
Key to MiST Hydrology
Section 1. VEGETATION
1. Mitigation site (MiS) is a juridictional
forested wetland 2
1. MiS is not as above V3
2. MiS is currently a forested wetland ecosystem
that will be removed or replaced prior to or ^
as part of the execution of a mitigation plan V3
2. MiS is not as above 3
3. Identify Reference Forest Ecosystem (RFE). MiS has
greater than 85% of the overstory species cover
AND composition relative to that present on the RFE 4
3. MiS vegetation is not as above 5
4. MiS has greater than 85% of the understory
species cover AND composition relative to the RFE.... VO
4. MiS vegetation is not as above 5
5. MiS has greater than 50% and less than 85%
of overstory species cover relative to that
present on the RFE 6
5. MiS vegetation is not as above V2
6. MiS has greater than 50% and less than 85%
of understory species cover relative to that
present on the RFE 7
6. MiS vegetation is not as above V2
7. MiS has greater than 50% and less
than 85% of overstory species
composition relative to the RFE 8
7. MiS vegetation is not as above V2
8. MiS has greater than 50% and less
than 85% of understory species
composition relative to the RFE VI
8. MiS vegetation is not as above V2
Forested wetland ecosystems as considered here include
the vegetation, soils, and hydrology of the site.
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Section 2. SOILS
1. MiS is a jurisdictional wetland 2
1. MiS is not as above S4
2. MiS soils will be removed prior to or as part
of mitigation plan 3
2. MiS soils are not as above 4
3. Surface (A) horizon and subsurface (B)
horizon to be replaced on MiS in
their entirety S3
3. MiS soils are not as above S4
4. Identify and characterize the chemical and physical
properties of the soils found on the RFE 5
5. MiS soils have lost greater than 12 inches from
the top of the profile when compared to
existing, undisturbed, similar soil series S4
5. MiS soils are not as above 6
6. MiS soils have lost between 6-12 inches from
the top of the profile when compared to existing
undisturbed, similar soil series S2
6. MiS soils are not as above 7
7. MiS soil rooting zone significant-
ly more compact than RFE rooting zone S2
7. MiS soils are not as above 8
¥¥¥
8. Chemical or physical disturbance
limited to the top 12 inches of MiS soil SI
8. MiS soils are not as above SO
Properties of soil series are defined in current Soil
Survey of the county where the mitigation site resides
or must be defined by a soil scientist familiar with
hydric soils and their properties in the region of the
mitigation site.
¥¥
Significance of soil compaction is a function of both the
quantitative estimate of the level of compaction and
the relative proportion of the mitigation site that is
compacted.
¥¥¥
Chemical and physical disturbance includes, but is not
limited to, loss of litter layer or up to 6 inches of
the top of the profile, presence of materials
(nutrients, toxic chemicals, materials that disrupt
gaseous or liquid exchange, etc.) at a level high
enough to inhibit productivity of the site (relative to
the RFE) and significant changes'in redox potential.
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Section 3. HYDROLOGY
1. MiS is a jurisdictional wetland 2
1. MiS is not as above H4
2. Identify and characterize the frequency,
duration, seasonality, and source of
hydrologic inundation to the RFE 3
3. MiS seasonality of inundation differs
from that present on the RFE H4
3. MiS hydrology is not as above 4
4. MiS source of inundation differs
from that present on RFE H4
4. MiS hydrology is not as above 5
5. MiS frequency of inundation deviates
from that present on the RFE by
less than 10% 6
5. MiS hydrology is not as above 7
6. MiS duration of inundation deviates
from that present on the RFE by
less than 10% HO
6. MiS hydrology is not as above 7
7. MiS frequency of inundation deviates
from that present on the RFE
by 10% to 25% 8
7. MiS hydrology is not as above 9
8. MiS duration of inundation differs
from that present on the RFE by
10% to 25% HI
8. MiS hydrology is not as above 9
9. MiS frequency of inundation
deviates by 25% to 50% from
that present on the RFE 10
9. MiS hydrology is not as above.... H3
10. MiS duration of inundation
deviates by 25% to 50% from
that present on the RFE H2
10. MiS hydrology not as above.. H3
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SELECTION OF A REFERENCE FOREST ECOSYSTEM:
ISSUES AND APPROACHES
T.A. White
This document strives to provide technical assistance in the
evaluation of mitigation plans. However, the selection of che
Reference Forest Ecosystem (RFE), fundamental to the use of MiST,
raises a number of practical issues that should be considered by
mitigators, regulators and policymakers. The purpose of this
section is to illuminate at least a portion of the issues
surrounding the selection and use of the RFE in the MiST system.
Introduction
Permitted impacts to forested wetland ecosystems may require
compensatory mitigation in the form of creation, restoration, or
other types of replacement. Monitoring is required of the
mitigation project to ensure that ecosystem structure and
function are on the appropriate trajectory for successful
replacement to occur. Establishing this trajectory would ideally
be accomplished by monitoring the proposed impact area
simultaneously with the mitigation project area. In that manner,
one would know how the mitigation compared to the actual function
of the impacted site over a similar time frame.
However, in most cases, the "up-front" mitigation type
described above is not an available option for a variety of
reasons. A common reason is the relative time period required
for mitigation establishment and monitoring is much greater than
that required for completion of projects proposed for 404
permitting. Consequently, the impacted area often cannot serve
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as half of the monitored pair for assessing mitigation success.
In these instances, one must use a reference wetland to act as a
surrogate for the area to be impacted. The reference wetland is
defined here as a field community of organisms with attributes
similar to the area to be filled.
While the reference wetland concept is sound on paper, the
procedures for selecting it are often problematic. Several
direct and indirect issues arise when attempting to define it.
For this reason, the MiST document proposes use of the
Reference Forest Ecosystem (RFE) concept in place of the
reference wetland as a means to monitor forested wetland
mitigation projects. Selection of the RFE is fundamental to the
implementation of MiST. As well as forming the basis for
quantitative mitigation performance standard comparisons, the RFE
also serves as a goal toward which to direct mitigation design
and implementation efforts.
Issues surrounding the selection of the RFE
The RFE is defined earlier in this document as "The kind of
forest selected for creation or restoration, as it is represented
locally (same or nearby watershed) in terms of species
composition and physiognomy. It is imcumbent upon the applicant
to characterize the reference forest type to the satisfaction of
the regulatory authority."
The RFE departs from the reference wetland approach in
several important ways. Depending upon the site attribute, the
RFE may be equal or very similar to the reference wetland or it
may be quite different. It is, at least in part, a conceptual
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model. To examine the reasons for selecting the RFE based on a
conceptual/field model rather than strictly an on-site approach,
both direct and indirect issues will be discussed.
Direct issues
Vegetation
Species composition of the RFE should attempt to emulate the
area proposed for impact. Yet, a key consideration in the
selection of the RFE is to define exactly what the RFE is
attempting to replace. Locating undisturbed forested wetland
ecosystems is, at best, difficult on a regional basis and often
impossible at the watershed-specific level. Studies indicate
that even in relatively undisturbed forested wetland ecosystems
considerable intra-stand species composition and dominance often
are the rule (Clewell and Lea, 1989). Moreover, some sites have
otherwise suitable overstories that have been overrun with exotic
competitors such as Pueria or Lonicera. Consequently, selecting
a RFE on the basis of species composition representative of a
particular watershed is likely to be not only difficult to
replicate but often undesirable as well.
Similarly, if the permitted fill area is a degraded wetland
initially, the desirability of replacing this ecosystem may be
questionable. In many cases, opportunities exist for enriching
the mitigation area with additional species whose presence in the
current landscape (including the permitted area) is diminished or
entirely lacking. For example, suppose a permitted area is
composed of a poorly stocked, monospecific river birch (Betula
nigra) community. In the reference wetland approach, mitigation
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for this impact should replace the river birch community. In
cases where river birch communities are not frequent; on the
landscape, this may be desirable. However, on landscapes where
these communities are commonplace and where mast-producing
species are lacking, a replacement forested wetland such as one
dominated by overcup or Nuttall oaks (Quercus lyraca and Quercus
nutallii, respectively) would have greater habitat value. Thus,
while species composition should always be a focal point, it
should not necessarily drive the selection of the reference.
The RFE provides positive flexibility to the reference
wetland concept and allows the establishment of the oak community
in spite of its relative absence from the local flora. RFE
selection should use the species composition of an impacted area
as a minimum sideboard to the mitigation project; species
composition changes should be done in conjunction with regulatory
and commenting agencies.
Habitat
Similar to vegetational condition, the habitat type present
on many forested wetlands is often degraded. Consequently,
opportunities to improve upon existing habitat in a particular
watershed should, in many cases, outweigh the desirability of
reproducing inferior habitat that might exist on available
reference wetlands.
Soils and Hydrology
In contrast to vegetation and habitat, field characterization
of soils and hydrology of the RFE is a crucial component in its
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selection. The soils-hydrology combination drives the
development of any wetland community and the selection of RFZs
with similar soils and hydrology to the impacted wetland is
considered important for ensuring that many functional
performance standards are achieved. Review of soil survey maps,
historical hydrologic data, and field evaluations of both are
recommended as part of the selection process.
Failure of many forested wetland mitigations can be traced to
inadequate establishment of site hydrologic conditions
appropriate to the tolerances of the woody species planted there.
Understanding the hydrologic conditions of the RFE is best done
in situ so, in the case of hydrology, the RFE and reference
wetland concepts are similar.
MiST soils requirements do not necessarily attempt to
duplicate entire soil profiles and are purposely open with regard
to specific levels of soil attributes as they reflect the RFE. A
good theoretical basis exists for this approach. First, similar
to the reasoning for allowing freedom (with regulatory approval)
to determine vegetational composition, situations exist in the
landscape to improve upon bottomland soil properties that might
benefit the overall productivity and site functions related to
productivity such as food chain support.
Second, natural ecosystems are subject to environmental
extremes in temperature and water availability during the growing
season. High soil water tensions have the additional indirect
effect of temporarily reducing nutrient availability. One reason
that wetland ecosystems are often the most productive within a
given watershed (indeed, in some cases, representing the most
75
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productive ecosystems in the world) is that they are naturally
buffered from environmental extremes as a result of their
position in the landscape.
Soils act as a medium for retaining and conducting water ana
nutrients to the rhizosphere and for anchoring the plant (as well
as habitat for many organisms). Regulations requiring
replacement of specific thicknesses of soil on upland sites have
their theoretical foundation in assuring that the site has
sufficient soil volume (and, thus, sufficient water and nutrient
availability) to insulate it from the environmental extremes
normally present during the growing season. Yet, since wetland
soils are naturally buffered from these extremes, it may be
inappropriate to equate the potential impacts of upland soil
disturbances with similar disturbances on wetland soils.
As a consequence of the above, the driving force behind
forested wetland soil replacement should be the assurance that
the soil has the physical and chemical attributes suitable for
good plant growth. This does not mean the soils will not be
monitored; a vigorous soils monitoring program is required from
all mitigations including measurement of the levels of total N,
P, K and other macronutrients as well as micronutrients.
Materials toxic to plant growth and physical attributes are also
monitored. While pedogenic similarities between RFE and
mitigation soils are not required, comparisons of the above
parameters are part of the monitoring program. Nevertheless,
since the aim of all forested wetland mitigation projects is to
produce a fully functional ecosystem, the mitigator myst
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carefully compare the benefits of mitigation designs with the
cost of not attaining performance standards.
Water Quality
The RFE and reference wetland concepts are similar in the
evaluation of water quality functions. Consideration of the
ability of the constructed forested wetland to improve water
quality is not only one of the most important aspects in the
choice of the RFE but also a factor that can make RFE
identification difficult. To minimize confoundment in the
assessment of water .quality -improvement, RFE selection should
attempt to equalize relative cumulative effects between the RFE
and the mitigation site. At a minimum and to the extend
possible, the RFE should emulate the forested wetland ecosystem
that will be impacted or the condition that existed prior to the
impact. Since all mitigations strive to replace ecosystem
function as well as form, a landscape level approach should
identify not only site specific functional effectiveness, but
also the opportunity and social significance of site functions.
In short, activities within the RFE watershed should be as
similar as possible to those within the permitted and mitigation
site watershed(s) particularly on-site and upstream. The easiest
way to ensure this is to select a RFE within the same basin and
in a similar topographic position as the impacted area. However,
in many cases, this option may not be available and one must look
outside of the impacted watershed boundaries. This latter case
may require more information than the former. While it may not
be necessary in many cases, where selection of the RFE is
controversial, one may wish to employ a Wetland Evaluation
77
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Technique (WET) analysis (Adamus, 1987) to the potential RFE to
ensure that the functional relationships of the off-watershed RFE
approach those of the impacted area. This option is particularly
useful in urban situations where development has caused
significant changes to the upstream and downstream
characteristics of the watershed.
Finally, as a result of the above complications and to
alleviate the impact of any changes in upland land use upon water
quality assessment, the Water Quality working group suggests
selecting more than one RFE for this purpose. This determination
must be done on a case-by-case basis.
Indirect issues
In some instances, the land base of the permit applicant may
not contain a suitable RFE. In other situations, forested
wetland disturbance may be so severe that a suitable RFE may not
be available in the vicinity of the mitigation site. Some
alternatives must be available to the permit applicant to offset
such situations. A limited set of alternatives is presented
here.
One alternative would be to obtain an easement from an
adjacent landowner(s) on whose property a suitable RFE might
reside. Another alternative would be to utilize portions of
public lands such as state, national, or university forests as
RFEs. Use of either of these options would depend upon the
proximity of the RFE to the mitigation site, its vegetation,
soils, and hydrologic makeup, position within the watershed,
similarity to the impacted site, etc. Moreover, their
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utilization would require agreements between the permittee and
the organization with authority over the proposed RFE. Selection
of off-site RFEs must be made with extreme care and on a
case-by-case basis to ensure that functions are monitored
properly.
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GLOSSARY
AND
LITERATURE CITED
-------
GLOSSARY
CANOPY: The uppermost stratum of trees in the reference fores-
ecosystem.
COMPACTION: Degree of firmness in the soil. When present at a
high degree, it reduces water,movement and limits plant root
penetration. Relative degrees can be determined by comparing
bulk density and/or soil strength (e.g., as measured with a
constant rate penetrometer).
DURATION: The average length of time in months that inundation
and/or saturation occurs each year.
FREQUENCY: The number of inundation and/or saturation events
that occur on the average each year. At least one inundation
/ saturation event must occur on the average each year to
meet Federal guidelines.
HABITAT: The total of environmental conditions of a specific
place occupied by a wildlife species or a population of that
species. It can be described in terms of food, water, cover,
and any other recognized life requisites and their relative
location (interspersion) within a given area.
NATURAL DISTURBANCE: Physical processes (i.e., soil scouring,
sediment deposition) normally associated with inundation of
floodplain zones.
NEW SOIL: Recently deposited or drastically altered soil
profiles atypical of undisturbed soils within the reference
area (e.g., dredge spoil, mine tailings, mixed mine soil,
overburden, construction backfill material).
NUISANCE SPECIES: Competitive weeds, vines, or other plants
having the potential to retard project development and
release.
PEAK FLOW: The maximum flow that occurs during a given stormflow
event, usually expressed as cubic feet per second (cfs).
PREFERRED SPECIES: Plant species typical of the RFE that serves
as the model for mitigation. Preferred species generally
exclude exotic species, aggressively colonizing weeds of open
environments, non-persisting canopy gap herbs, off-site
species that may occur sporadically in the RFE but that are
more typical of other ecosystems, and rhizomatous grasses
with the propensity to form turfs.
REFERENCE FOREST ECOSYSTEM: The kind of forest selected for
creation or restoration, as it is represented locally (same
or nearby watershed) in terms of species composition and
physiognomy. It is incumbent upon the applicant to
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characterize the reference forest type to the satisfaction c:
the regulatory authority.
REFERENCE SOIL: Soil type(s) associated with the reference
forest ecosystem.
SEASONALITY: The season or seasons (growing and dormant) during
which the dominant period of inundation and/or saturation
occurs. The dominant season of inundation cannot be
different from the reference BLH forest ecosystem, otherwise
a different forest ecosystem would develop over time.
SOURCE: The principal source of inundation and/or saturation
such as riparian (upland) discharge, overbank flow and rising
groundwater. The dominant source of inundation cannot be
different from the reference BLH forest ecosystem.
UNDERGROWTH: All species of vascular plants of the RFE that do
not contribute ordinarily to the canopy (except as vines or
epiphytes), including herbs, vines, shrubs, and small trees.
UNDISTURBED NATURAL AREAS: BLH forest communities that do not
exhibit evidence of an adverse impact by man-made activities
(e.g., logging, grazing, agriculture, construction runoff and
sedimentation).
WETLAND HYDROLOGY: The hydrologic factors such as frequency,
duration, seasonality, and source of inundation and/or soil
saturation resulting in maintenance of a reference BLH forest
ecosystem (as further defined in the Vegetation Criteria
Section). By definition, the reference BLH forest ecosystem
must meet Federal criteria for jurisdictional delineation as
a wetland.
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