United States
Environmental Protection
Mm Agency
Implementing the Biological Condition
Gradient Framework for Management
of Estuaries and Coasts

Office of Research and Development
National Health and Environmental Effects Research Laboratory

May 2017
Implementing the Biological Condition Gradient Framework
for Management of Estuaries and Coasts
Giancarlo Cicchetti
Marguerite C. Pelletier
Kenneth J. Rocha
Patricia Bradley (retired)
Atlantic Ecology Division
National Health and Environmental Effects Research Laboratory
Narragansett, Rl
Deborah L. Santavy
Gulf Ecology Division
National Health and Environmental Effects Research Laboratory
Gulf Breeze, FL
Margherita E. Pryor
Region 1,
Boston, MA
Susan K. Jackson
Office of Water
Washington, DC
Susan P. Davies (retired)
Maine Department of Environmental Protection
Augusta, ME
Christopher F. Deacutis
Rl Department of Environmental Management
Jamestown, Rl
Emily J. Shumchenia
Great Lakes Environmental Center
Traverse City, Ml
National Health and Environmental Effects Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Atlantic Ecology Division
Narragansett, Rl

Implementing the Biological Condition Gradient Framework
Notice and Disclaimer
The EPA Office of Water's Biological Condition Gradient method was originally developed for
application to freshwater streams. This document adapts that approach for use in larger and more
complex estuarine and coastal systems. The discussions in this document are intended solely to
provide information on advancements in the field of biological assessment. The EPA through its Office
of Research and Development, Office of Water, and Region 1 funded and collaborated in the research
described here. This document has been subjected to the Agency's peer and administrative review
and has been approved for publication as an EPA document. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use. While this manual describes
EPA's scientific recommendations regarding biological assessment to help protect aquatic life in
coastal and estuarine ecosystems, it does not substitute for CWA or EPA regulations, nor is it a
regulation itself. Thus, it cannot impose legally binding requirements on EPA, states, territories,
tribes, or the regulated community and might not apply to a particular situation or circumstance.
EPA may change this guidance in the future. All environmental data in this document are reported in
the published literature and are used here to illustrate the Biological Condition Gradient development
process. This is a contribution to the EPA Office of Research and Development's Safe and Sustainable
Waters Research Program.
The appropriate citation for this report is:
Cicchetti, G., M.C. Pelletier, K.J. Rocha, P. Bradley, D.L. Santavy, M.E. Pryor, S.K. Jackson, S.P. Davies,
C.F. Deacutis, and E.J. Shumchenia. 2017. Implementing the Biological Condition Gradient Framework
for Management of Estuaries and Coasts. U.S. Environmental Protection Agency, Office of Research
and Development, Atlantic Ecology Division, Narragansett Rl. EPA/600/R-15/287.
This document can be downloaded from:
Cover photos, clockwise from upper left: 1) Entrance to Point Judith Pond, Narragansett, Rl.
2) Scientist collecting data, La Parguera reefs, PR. 3) Shipping cranes, San Pedro Harbor, Los
Angeles, CA. 4) Kayakers enjoying Caribbean coastal waters. 5) Elkhorn coral, Dominican Republic.
6) Mary Donovan Marsh, Little Compton, Rl.

Table of Contents
Table of Contents
Notice and Disclaimer	ii
Figures	iv
Tables	v
List of Acronyms	vi
Acknowledgments	vii
Executive Summary	viii
1.	Introduction	1
2.	The BCG in freshwater systems	5
2.1.	Key terms for BCG	7
2.2.	Overview of BCG	7
3.	Estuarine and coastal BCG implementation	9
3.1.	How can the BCG be implemented in estuarine and coastal settings?	9
3.2.	Development of estuarine/coastal BCG guidance	12
4.	Components of the estuarine/coastal BCG	23
4.1 Attributes and measures	23
4.2.	BCG levels	29
4.3.	The Generalized Stress Axis	36
5.	Application of the approach: details and examples	39
5.1.	Classification	39
5.2.	How can the BCG improve management of estuaries and coastal waterbodies?	42
5.3.	The BCG as part of larger social/ecological/economic management approaches	44
5.4.	Overall estuary or waterbody condition	49
5.5.	Sustainability and the estuarine/coastal BCG	56
6.	Results from early pilots	61
6.1.	Narragansett Bay	61
6.2.	Tampa Bay	66
6.3.	Mobile Bay	71
6.4.	Lower Columbia River	74
6.5.	Puerto Rico coral reefs	77
7.	Summary and next steps	85
References	89
Appendix A. Attributes and narratives to assign BCG levels in streams	97
Appendix B. The BCG for estuaries and coasts: FAQs	102
Appendix C. Attendees at the 2008 workshop	109
Appendix D. Attendees at the 2009 workshop	110

Implementing the Biological Condition Gradient Framework
Figure 1-1. Docks, roads, commercial fishing vessels, marine transportation, and industry in
Point Judith Harbor, Rl	1
Figure 1-2. Charleston Harbor, SC, an important low-lying urban southeastern estuary	3
Figure 2-1. Freshwater stream, Yosemite National Park, CA	5
Figure 2-2. Conceptual model of the BCG as developed for streams	6
Figure 3-1. Researcher collecting scientific data for a coral reef BCG, La Parguera, PR	9
Figure 3-2. The Providence River in Narragansett Bay, Rl, after 400 years of post-colonial
development	10
Figure 3-3. Woods Hole, MA, a complex coastal system	11
Figure 3-4. SNA map of collaborations within the Piscataqua River Estuary Program	14
Figure 3-5. Estuarine benthic invertebrates, often the basis of estuarine assessment	15
Figure 3-6. Scientists collecting the new data required to construct a coral reef BCG,
southwestern PR	16
Figure 3-7. Steps for calibration of a quantitative BCG	18
Figure 3-8. Oceanic influence near the mouth of Narragansett Bay, Rl	20
Figure 3-9. Taskinas Creek, part of the Chesapeake Bay NERR in Virginia	22
Figure 4-1. Seagrass is a biotope and a sensitive indicator of condition	24
Figure 4-2. Non-native taxa: dead man's fingers	25
Figure 4-3. Sediment profile image	26
Figure 4-4. Hydrological evidence for poor connectance-Watchemoket Cove, Rl	27
Figure 4-5. HICO satellite image of the Columbia River, OR and WA	28
Figure 4-6. Thicket of Acroporo cervicornis (staghorn coral) and reef fishes indicative of
coral reef BCG levels 1 and 2	32
Figure 4-7. Seagrass with barracuda	33
Figure 4-8. Small cove in Black Rock Harbor, CT	37
Figure 5-1. Two adjacent lagoonal estuaries (Green Pond and Great Pond, Cape Cod, MA)	39
Figure 5-2. An anthropogenic estuary built behind breakwaters (San Pedro Bay and Long Beach,
Los Angeles, CA)	40
Figure 5-3. Entrance to a small riverine estuary (Narrow River, Rl)	41
Figure 5-4. Large charismatic animals appeal to public sentiment, and are often dependent on
high water quality and suitable habitat availability	45
Figure 5-5. Charismatic brown pelican in Tampa Bay, FL	48
Figure 5-6. West Falmouth Harbor, MA	49
Figure 5-7. Seagrass habitat is important for the settling and development of juvenile conch	51
Figure 5-8. Aerial views of heads of two sub-estuaries showing biotopes	52
Figure 5-9. Migrating coho salmon show connectance between oceans, estuaries, and streams	54
Figure 5-10. Northeast corner of Greenwich Bay, Rl	55
Figure 5-11. Economy: investment in recreational fishing. Columbia River, OR and WA	57

Figures and Tables
Figure 5-12. Environment: seagrass and staghorn coral, both sensitive species,
in the Florida Keys Marine Sanctuary	57
Figure 5-13. Society: public enjoyment of the seashore. Town Beach, Charlestown, Rl	58
Figure 6-1. Narragansett Bay, Rl	61
Figure 6-2. Greenwich Bay, Rl, located mid-bay on the western shore of Narragansett Bay	63
Figure 6-3. The ecological and cultural history of Greenwich Bay	64
Figure 6-4. Habitat structure BCG model for Greenwich Bay	65
Figure 6-5. Tampa Bay, FL	66
Figure 6-6. TBEP graphic to describe 'Restoring the Balance'	68
Figure 6-7. Biological gradient for biotopes of Tampa Bay	69
Figure 6-8. Be Floridian sign	70
Figure 6-9. Road sign showing FL DOT support of the Be Floridian campaign	70
Figure 6-10. Mobile Bay, AL	71
Figure 6-11. Create a Clean Water Future campaign-changing public attitudes	72
Figure 6-12. Natural beauty of Three Mile Creek, Mobile Bay, AL	72
Figure 6-13. Another image from Three Mile Creek, Mobile, AL, illustrating the need to change
public actions	73
Figure 6-14. The Columbia River	74
Figure 6-15. Prairie Channel (WA) and the natural beauty of the Lower Columbia Estuary	75
Figure 6-16. Stakeholder investment: paddlers on the Lower Columbia Estuary	76
Figure 6-17. The stretch of reefs from La Parguera to Guanica Bay, southwestern PR	77
Figure 6-18. Diagram showing ecosystem connectance	78
Figure 6-19. EPA coral reef sites reflect a range of coral reef conditions	79
Figure 7-1. Photo montage of public/stakeholder interest in estuaries and coasts	85
Figure 7-2. Eroding marsh edge	87
Figure B-l. Conceptual model of the BCG as used in freshwater	103
Figure B-2. Excerpt from Buzzards Bay Report Card output	107
Figure B-3. 2012 Chesapeake Bay Report Card output	108
Table 4-1. Five attributes and potential measures for application to estuarine and coastal BCGs
at different scales	23
Table 4-2. Attributes and potential measures developed at the 2008 Estuarine BCG workshop	30
Table 4-3. Strengths and weaknesses of various methods used to determine undisturbed or
minimally disturbed conditions	32
Table 6-1. Summary descriptions of four coral reef condition categories (very good to poor)
based on expert assessments of individual stations	80
Table A-l. Ecological attributes and possible measures paired with example narratives for
BCG levels	97
Table A-2. Detailed matrix of Taxonomic Composition and Structure Attributes l-V for streams	101

Implementing the Biological Condition Gradient Framework
List of Acronyms
ALU	Aquatic Life Uses
AUV	Autonomous Underwater Vehicle
BCG	Biological Condition Gradient
CMECS	Coastal and Marine Ecological Classification Standard
CMSP	Coastal and Marine Spatial Planning
CPUE	Catch Per Unit Effort
CWA	Clean Water Act
CWA 303(d) Clean Water Act List of Impaired Waters
DPSIR	Drivers-Pressures-State-Impacts-Responses
EBM	Ecosystem-Based Management
EPA	Environmental Protection Agency
EU	European Union
FGDC	Federal Geographic Data Committee
GSA	Generalized Stress Axis
HICO	Hyperspectral Imager for the Coastal Ocean
IBI	Index of Biological Integrity
LCEP	Lower Columbia Estuary Partnership
MBNEP	Mobile Bay National Estuary Program
NBEP	Narragansett Bay Estuary Program
NCCA	National Coastal Condition Assessment
NEP	National Estuary Program
NERR	National Estuarine Research Reserve
NGO	Non-Governmental Organization
NOAA	National Oceanic and Atmospheric Administration
RPB	Regional Planning Body
SCCWRP	Southern California Coastal Water Research Project
SDM	Structured Decision Making
SNA	Social Network Analysis
TBEP	Tampa Bay Estuary Program
TALU	Tiered Aquatic Life Uses
TMDL	Total Maximum Daily Load
USCRTF	United States Coral Reef Task Force
WFD	Water Framework Directive
WQS	Water Quality Standards

This work was inspired by the earlier work of those scientists who developed the foundational
concepts of integrity, condition, bioassessment, biocriteria, and related topics. We thank the many
scientists who participated in our 2008 and 2009 workshops for their insights and contributions to
this effort. We are grateful to Holly Greening of the Tampa Bay Estuary Program for her continued
support. We recognize Catherine Corbett of the Lower Columbia Estuary Partnership as well as
Tom Herder and Roberta Swann of the Mobile Bay Estuary Program for their BCG work and insightful
comments. Marnita Chintala of the U.S. EPA Atlantic Ecology Division promoted these efforts,
while Naomi Detenbeck, Dan Campbell, and Elizabeth Watson (also of the Atlantic Ecology Division)
provided thoughtful reviews of this document.

Implementing the Biological Condition Gradient Framework
Executive Summary
Estuaries and coastal systems are areas of confluence and connection. The river and the land meet
the ocean here, resulting in steep gradients of habitat change, a diversity of life, and high biological
productivity. People also meet the ocean here and have been attracted to coastlines for many
thousands of years. Human populations are expanding rapidly on our coasts; this leads to increased
environmental stressors (including excess nutrients, habitat alteration, and toxic pollution) and the
need for more effective management of these valuable areas.
Living organisms respond to the cumulative impacts of all stressors, and natural populations of biota
have been affected for centuries. These biological changes can be addressed with bioassessments-
evaluations of the biological condition of a waterbody using surveys of the structure and function of
biotic elements. Bioassessment puts a spotlight on biology and allows managers to address the
cumulative impacts that degrade environmental condition. Bioassessment in estuaries and coasts
integrates many of the upstream stressors in the larger watershed as well as stressors within the
waterbody and is a vital part of managing at the waterbody and watershed levels.
The Biological Condition Gradient (BCG) is a conceptual scientific framework for interpreting biological
response to increasing effects of stressors on aquatic ecosystems (U.S. EPA 2016). The framework was
developed from common patterns of biological response to stressors observed empirically by aquatic
biologists and ecologists in different geographic areas of the United States. The framework describes
how attributes of aquatic ecosystems change in response to increasing levels of stressors, from an "as
naturally occurs" condition (e.g., undisturbed or minimally disturbed) to a severely altered condition.
The highest level of condition, level 1, represents natural or undisturbed biological communities and
anchors the starting point for defining five levels of change or departure from this condition with level
6 representing conditions that have been severely altered due to anthropogenic stress. Each level is
defined by a narrative description that can be consistently interpreted regardless of biology, location,
or sampling method. These narratives are translated into quantitative decision rules for specific local
areas through expert consensus. The BCG end product is a set of well-vetted and transparent decision
rules that can be readily interpreted and implemented by state water quality program managers and
scientists, and can be easily understood by stakeholders, the public, and higher levels of management.
This process provides the conceptual basis for comparable interpretation of assessments and for
clear communication of condition, because the levels have the same basic meaning wherever BCG
is applied. Level 4 for fish in a New Jersey estuary describes the same relative biological condition
as level 4 for invertebrates in a Maine stream, although in practice the different datasets used in
analyses will introduce variability. The BCG provides a tool for effective comparisons of condition
across time and among waterbodies, allowing managers to support Clean Water Act (CWA) and
Total Maximum Daily Load (TMDL) programs, communicate relative condition, develop thresholds,
set goals, and monitor progress towards these goals. The BCG framework was initially developed
for application in freshwater streams and has been applied in these environments for years as a
management tool to interpret baseline conditions, identify high quality waters, and define attainable
goals for improvements in degraded waters.

Executive Summary
This document expands the stream BCG framework and proposes guidance for estuarine and coastal
BCG implementation as a sequence of actions or steps to assist estuarine and coastal scientists and
managers as they plan and implement environmental decisions. The initial Steps (1-7) walk scientists
and managers through identifying stakeholders, problems, goals, and relevant biological indicators
to develop a descriptive BCG. This phase establishes a common understanding among potential users
on the role of a BCG in meeting their specific resource management needs. For example, a
descriptive (qualitative) BCG can be used to refine stakeholder visions, improve narrative designated
use categories, set broad goals, and communicate biological condition to motivate the public. The
last set of actions or Steps (8-11) guide development of a more rigorous quantitative BCG that can
help establish numeric thresholds for assessing biological condition, inform CWA decisions, track
changes in condition, develop biological criteria, and monitor to evaluate management actions.
The approach is flexible-coastal and estuarine managers can choose to develop any of the steps that
would best meet their requirements, and in any order. National Estuary Programs (NEPs) were the
first groups to adopt this BCG implementation guidance, and the approach is well suited to address
many of their needs. Implementation steps of estuarine/coastal BCG development are:
1.	Define problems, engage partners and stakeholders
2.	Collaborate to define management goals, visions, and objectives
3.	Determine the biological components, stressors, measures, and attributes most relevant
to management objectives
4.	Delineate and classify the waterbody and watershed of interest
5.	Organize and analyze existing data for the identified measures, collect new data if needed
6.	Define BCG level 1 conditions for the identified attributes
7.	Develop narrative descriptions of the biology expected at each BCG level as a narrative
BCG model; apply to management needs
8.	Convert narrative descriptions to quantitative metrics and thresholds, calibrate the BCG
9.	Develop a stressor gradient and stressor-response relationships
10.	Organize, interpret, and report results
11.	Develop decision support, communication, and monitoring tools; assist management
These BCG implementation steps provide a path for scientists and managers to identify and solve
environmental problems. The methods and outputs can be tailored to larger well-funded programs
such as state and federal agencies or to smaller programs with fewer resources including NEPs,
National Estuarine Research Reserves, town or county governments, and local Non-Governmental
Organizations (NGOs) or coalitions.
The estuarine and coastal BCG offers an easily understood method for communicating biological
condition in a way that engages the public and other stakeholders. BCG levels can be used at the
waterbody scale to define current biological conditions for determining attainment of CWA goals;
set non-regulatory goals and targets for attaining a desired biological or ecological condition;
and track environmental progress towards achieving targets and goals. NEPs who have used the
estuarine and coastal BCG identify the ability to set meaningful targets for habitat protection and

Implementing the Biological Condition Gradient Framework
restoration, and the ability to positively engage the public and other stakeholders as primary benefits
of the approach. At the national scale, consistent interpretation of biological assessments in
estuaries and coasts allows for comparisons across waterbodies and better reporting of condition
in national surveys, including documentation of successes in restoring or protecting these critical
resources. This application of the BCG to estuaries and coasts is adaptable and can be modified for
other waterbody types that are studied and managed as individual systems. The process is well
underway for estuaries and coral reefs and could also be applied to large rivers, lakes, and other
This document serves as technical guidance for scientists and managers taking on projects that would
benefit from use of bioassessment to manage complex coastal systems. BCG methods are described
in a logical order of development steps, with recommendations for different uses of BCG in
management. Case studies illustrate applications of this approach to waterbodies in a variety of
geographic and ecological settings.

1. Introduction
1. Introduction
Cumulative impacts and bioassessment
Estuaries and other coastal systems are among the environments most influenced by human
activities. These waters are affected by a variety of stressors that act at several scales, including
localized point sources of contaminants, anthropogenic inputs from the watershed and the ocean,
habitat destruction, widespread or diffuse non-point sources of contaminants, biological harvesting,
and larger scale impacts such as sea level rise (Figure 1-1). These valued ecosystems, and their biota,
are significantly altered by the cumulative impacts of multiple stressors. Over time, this has led to
"severe, long-term degradation of near-shore marine systems worldwide" (Lotze et al. 2006).
Effective management of cumulative impacts on any scale requires coordination among management
entities and a variety of tools to quantify degradation, identify causes, address those causes, and
track progress. No single approach can address all of these issues, but evaluations of biology are very
often used to characterize and communicate the extent of anthropogenic degradation. Biological
condition integrates the effects of all the stressors that living organisms are exposed to and can be
an effective tool in managing cumulative impacts. Many different methods and indices to quantify
biological condition have been developed and applied by scientists, local resource managers, states,
and federal agencies. Most bioassessments evaluate changes in quality or quantity of ecologically or
economically defined condition or value of habitats, communities, or species, relative to a defined
reference state.
Figure 1-1. Docks, roads, commercial fishing vessels, marine transportation, and industry in Point Judith
Harbor, Rl, an illustration of estuarine uses and stressors.

Implementing the Biological Condition Gradient Framework
Consistent bioassessrnent
These assessments, when applied in different estuaries, often evaluate very different aspects of
biology and use different reference conditions, usually for the good reason that biology differs among
estuaries. Nonetheless, independent bioassessments do not allow comparisons among estuaries on
statewide, regional, or national levels. Estuarine managers have little context for how biological
condition in their waterbody compares to that in nearby estuaries, and larger-scale managers cannot
easily provide area-wide condition reports or analyses with which to focus priorities for protection or
One approach to common assessment is to employ an Index of Biological Integrity (IBI), which may be
developed for different assemblages (e.g., fishes, invertebrates) in local or regional areas. I Bis tend
to be well calibrated and effective for their local area of development, but results are generally not
applicable to other areas. The issue of regional comparability has led to development of a nationwide
estuarine benthic index using invertebrates (Gillette et al. 2015). However, nationwide indices for
other assemblages have not been developed, and local managers may not have the appropriate data
or resources to apply these approaches.
Other nationwide approaches, described in the Coastal and Marine Ecological Classification Standard
(CMECS), can be based on analyses standardized to infaunal community successional stage (FGDC
2012), or on image-based indices of condition, e.g., sediment profile cameras but these measures
may be less sensitive than well-tuned local indices. Further, the widespread use of different
bioassessrnent endpoints leads to reports that are not comparable among waterbodies, states,
or federal agencies. A common framework for interpreting data and assessment results and
communicating this information to stakeholders would enhance collaboration within and among
different agencies and assist in coordination of management actions.
The Clean Water Act
Certain regulatory actions require consistent assessments. Within the U.S. EPA, the vision of the
1972 Clean Water Act (CWA) provides a long-term national objective to "restore and maintain the
. . . chemical, physical, and biological integrity of the Nation's waters". Under the Act, states are
responsible for water quality management programs to assess the condition of their waters, set
designated uses, establish criteria in their Water Quality Standards (WQS), and then monitor
attainment of the uses. The CWA has led to tremendous environmental improvements, largely by
regulating point sources and individual chemicals (U.S. EPA 1986). The path to biological integrity,
however, has not been as clear cut. Biological integrity has been defined as "the capability of
supporting and maintaining a balanced, integrated, adaptive community of organisms having a
composition and diversity comparable to that of the natural habitats of the region" (Frey 1977),
but the term is not specifically defined in the CWA itself. Nor does the CWA define the ecological
components, or attributes, that constitute biological integrity (Davies and Jackson 2006).

1. Introduction
Given this lack of specificity, a way to interpret biological condition consistently and independently
of assessment methods would more clearly communicate the current status of aquatic resources and
their potential for restoration (Davies and Jackson 2006), allowing scientists and managers to better
assess aquatic resources. These gaps in the available management tools led the U.S. EPA Office of
Water Biocriteria Program to develop the concept of a BCG. The BCG framework (U.S. EPA 2016) is
a scientific model for consistent interpretation of biological response to increasing effects of stressors
on aquatic ecosystems. This bioassessmenttool supports CWA and other decisions in freshwater
streams and is now being applied to coastal and estuarine systems. The BCG anchors biological
condition to natural or undisturbed conditions (level 1) and describes five declining levels of condition
from that starting point, with level 6 representing severe alteration from undisturbed condition.
These level assignments are defined by consistent narratives and methods, allowing comparisons
of condition across sampling methods, biological endpoints, waterbodies, and time.
A flexible BCG approach for estuaries and coasts
The objective of this document is to propose an approach for applying the BCG framework to
improve management of estuaries and coasts. This is presented as a toolbox of steps or actions that
take scientists and managers from identifying environmental problems to applying BCG for solutions.
Early steps lead scientists, stakeholders, and managers through the process of defining management
needs and goals. Next steps develop a narrative BCG to communicate condition, create visions, and
set targets. In the final steps, a more rigorous quantitative BCG is developed to better support
management and regulatory actions to protect or improve estuarine and coastal ecosystems. The
guidance is not prescriptive, the steps need not be approached in any defined order, and coastal or
estuarine scientists and managers can develop any step
or steps they deem valuable for their specific needs.
This flexible approach can benefit states in regulating
water quality, NEPs in developing goals, plans and
actions or national and regional managers in comparing
condition among estuaries and waterbodies. All steps
are consistent with the essential tenets of the BCG
framework as developed for freshwater streams by
the U.S. EPA's Office of Water Bioassessment Program
(U.S. EPA 2016).
Figure 1-2. Charleston Harbor, SC, an important low-lying urban southeastern estuary.
Image: Google Earth, data from SIO, NOAA, U.S. Navy, NGA, GEBCO

Implementing the Biological Condition Gradient Framework
This document describes the BCG framework as applied to streams in Chapter 2, then defines
and explains the estuarine and coastal BCG guidance in Chapter 3. Chapter 4 provides more detail
on the key components of the guidance, Chapter 5 discusses how to apply the guidance, and
Chapter 6 presents BCG pilots. A summary and discussion of next directions can be found in
Chapter 7. This report is authored by a workgroup of scientists and managers who have been
developing and promoting BCG applications in estuaries, coral reefs, and other complex systems
since 2008.

2. The BCG in freshwater systems
2. The BCG in freshwater systems
Figure 2-1. Freshwater stream, Yosemite National Park, CA.
BCG fundamentals
The BCG framework was developed as a conceptual model for consistent interpretation and
communication of bioassessment information to improve management of freshwater streams
and wadeable rivers (U.S. EPA 2016). The model is based on a scientific understanding of how
ecosystems respond to increasing levels of human disturbance or stress. As shown in Figure 2-2,
the BCG describes a gradient in biological condition that ranges from a natural or undisturbed
condition (level 1) to a severely altered condition (level 6).
These changes in biology are evaluated through attributes, which are measurable and ecologically
important characteristics of the ecosystem. These attributes include measures of biological
and ecological structure, non-native taxa, organism condition, ecosystem function, spatial and
temporal extent, and connectance (U.S. EPA 2016). The BCG provides consistent and comparable
interpretation of assessments, because all evaluations are relative to the same fixed starting point
(or anchor) of undisturbed conditions, and because consistent narratives define every level for each
attribute regardless of waterbody or method. In practice, the BCG approach synthesizes existing
data, observations, and expert interpretations to document the response of aquatic biota to
increasing levels of anthropogenic stress. This approach helps identify environmental targets
and develop biological criteria that support conservation, restoration, monitoring, and
management activities.

Implementing the Biological Condition Gradient Framework
The Biological Condition Gradient:
Biological Response to Increasing Levels of Stress
Levels of Biological Condition
Level 1. Natural structural, functional,
and taxonomic integrity is preserved.
Level 2. Structure & function similar
to natural community with some
additional taxa & biomass; ecosystem
level functions are fully maintained.
Level 3. Evident changes in structure
due to loss of some rare native taxa;
shifts in relative abundance; ecosystem
level functions fully maintained.
Level 4. Moderate changes in structure
due to replacement of some sensitive
ubiquitous taxa by more tolerant
taxa; ecosystem functions largely
Level 5. Sensitive taxa markedly
diminished: conspicuously unbalanced
distribution of major taxonomic groups;
ecosystem function shows reduced
complexity & redundancy.
Level 6. Extreme changes in structure
and ecosystem function; wholesale
changes in taxonomic composition;
extreme alterations from normal
Watershed, habitat, flow regime	Chemistry, habitat, and/or flow
and water chemistry as naturally	regime severely altered from
occurs.	natural conditions.
Level of Exposure to Stressors
Figure 2-2. Conceptual model of the BCG as developed for streams with narratives for levels 1-6.
The actual relationships between multiple stressors and their cumulative impacts on biology are not likely
to be linear, although they are presented here as such to better illustrate BCG concepts.
Graphic: U.S. EPA 2016

2. The BCG in freshwater systems
2.1.	Key terms for BCG
Aquatic Life Uses: Beneficial use designations (for state water quality standards) describing
how the waterbody should provide suitable habitat for survival and reproduction of native
aquatic organisms.
Attributes: Characteristics of structure, non-native taxa, condition, function, landscape, or
connectance that reflect biological or ecological condition and represent biological integrity.
Used to organize measures and standardize narratives for each of (up to) six levels of
biological condition.
Bioassessment: The use of biological indicators to evaluate environmental condition.
Biological Condition Gradient (BCG): A conceptual scientific framework for interpreting biological
response to increasing effects of stressors on aquatic ecosystems.
Biological Condition: Levels of biological status defined by narrative or numeric decision rules
that are derived from empirically observed patterns of biological response to stressors.
The patterns associated with each BCG level are described by ecosystem characteristics or
attributes (see above).
Ecology: The relationship between living things and their environment. In a BCG, ecology
includes the interactions among organisms and with their physical/abiotic environments.
Estuarine and Coastal BCG: A conceptual scientific framework (BCG) for interpreting biological
response to increasing effects of stressors on complex, multi-habitat aquatic ecosystems,
adapting the freshwater BCG to include larger scale processes. This may also be referred to
as the Estuarine/Coastal BCG or the Estuarine BCG.
Estuarine and Coastal BCG Implementation: A set of steps to assist estuarine and coastal scientists
and managers from stakeholder engagement and problem formulation (Steps 1-3) through
BCG development and application (Steps 4-11).
Metric: As used in this document, a calculated term or enumeration that represents a quantifiable
biological feature that changes in a predictable way with increased human influence.
Measure: As used in this document, any quantitative, calculated, qualitative, narrative, or
descriptive evaluation of a biological feature that changes in a predictable way with
increased human influence. Measures include metrics.
2.2.	Overview of BCG
The major components of the BCG framework (U.S. EPA 2016) are as follows:
1.	Biological attributes are used to assess biological condition.
2.	The BCG defines six levels of biological response to increasing stress (Figure 2-2, page 6).
3.	The highest level of condition (level 1) is anchored in undisturbed conditions as naturally
occur. BCG level 2 represents minimally disturbed conditions. In many places undisturbed
conditions no longer exist and cannot be determined, so BCG levels 1 and 2 are combined
and considered comparable to naturally occurring conditions. The poorest condition (level 6)
is defined as severely altered and heavily disturbed by high levels of multiple stressors.

Implementing the Biological Condition Gradient Framework
4.	Expert best professional judgment and consensus in an empirically-based process
(U.S. EPA 2016) lead to development of narrative decision rules for assigning sites to
BCG levels. Application of independent data sets turns these decision rules into quantitative
thresholds using statistically based methods, modeling, or other technical approaches.
5.	The BCG process is based on scientific data. Thresholds are calibrated and validated with data,
and development steps are documented. This creates a transparent, testable, and defensible
assessment method with the clear thresholds needed to determine impairment and likely
trajectories of condition.
BCG levels 1-6 provide a 'common language' for assessment because the repeatable scientific
process can be applied anywhere that a full range of biological condition can be described with
any method of characterizing biology. These levels are used to interpret biological assessments,
then apply this information to management decisions in a way that is easily communicated to the
public. The BCG identifies both improvements and degradations to biological and ecological
condition and can help managers set targets in a transparent way and track environmental progress
towards these targets. Further, comparisons among waterbodies allow managers to understand
the success of efforts in different systems and to perhaps anticipate the effects on their own
systems if stressor levels change to more closely resemble those of other systems.
In practice, expert panels are used in stream BCG development to synthesize biological data,
assemble guidelines to define levels for each attribute (e.g., narrative and then numeric decision
rules, algorithms and models), and determine level thresholds for designated use assignments.
Stream ecosystems across the country have a long history of monitoring for macroinvertebrate,
fish, and periphyton communities, although different sampling techniques have been used. Stream
ecologists have a good understanding of how these biological communities respond as stressors
increase, and in many areas can identify level 1 and 2 sites (Figure 2-2, page 6) as examples of
undisturbed or minimally disturbed environments.
The BCG is based on elements of both science and management, with a focus on translating scientific
thinking and available data into clear quantitative thresholds for management decision-making.
A gap between research and management can occur when the greater understanding of pattern
and process sought by scientists does not directly lead to the easily communicated answers that
managers need. The BCG bridges this gap through expert scientist workshops and workgroups that
distill complex science into six consistent levels of condition that are easily understood and easily
communicated to the public.

3. Estuarine arid coastal BCG implementation
3. Estuarine and coastal BCG implementation
3.1. How can the BCG be implemented in estuarine and coastal settings?
Applying the BCG to estuarine and coastal areas relies on the concepts described above, but
requires a broader ecological approach to address the many different types of coastal waters
(Figure 3-1). This adaptation of the freshwater BCG takes a system-level view of the waterbody
and modifies attribute descriptions to cover larger scales of assessment. For example, it expands
the stream organism condition attribute to include habitat condition, e.g., wetland condition indices
which evaluate a variety of plant species, marsh ponding, and other wetland-specific features.
The estuarine/coastal BCG provides guidance for management groups to involve stakeholders
in defining problems and setting goals and allows a more flexible BCG that can be tailored to the
specific problems of an individual waterbody. This BCG can be used to assess condition of coastal
waterbodies in the past and present, and can be used to develop visions for desired future
conditions. It can assist in a variety of management applications including goal setting by NEPs
and regulatory actions by states, and can be applied by small programs with fewer resources.
Figure 3-1. Researcher collecting scientific data for a coral reef BCG, La Parguera, PR.
How is managing estuaries different from managing streams?
Estuaries and coastal waterbodies are very different from the stream reaches that are monitored
and assessed in many state water quality management programs and so require different assessment
and management strategies. Estuaries and coastal systems represent a large diversity of waterbody
types, from small lagoons to coral reefs. Many are characterized by rapidly changing natural
conditions (e.g., salinity and temperature shifts over a tidal cycle or along the estuarine gradient)
and most have a large diversity of habitats, each contributing to overall waterbody function.

Implementingthe Biological Condition Gradient Framework
Many estuarine species are extremely tolerant of stressors and environmental variability yet recent
anthropogenic changes have severely disturbed estuarine organisms, communities, and habitats
(Cloern et a 1.2016). Worldwide, estuaries and coasts are among the areas most densely settled
over long periods of time. Narragansett Bay, for example, has seen over 400 years of post-colonial
development and thousands of years of Native American settlement before that (Figure 3-2).
Most estuaries show significant degradation from the cumulative effects of anthropogenic stressors,
including shoreline development, nutrient inputs, habitat alteration, and overfishing (Lotze et al.
2006, Bricker et al. 2007, Bolster 2012).
Figure 3-2. The Providence River in Narragansett Bay, RI, after 400 years of post-colonial development.
Estuaries and stream reaches also differ from a management perspective. Estuarine and
coastal management often involves several different entities at national, state, and local scales,
including organizations with different scopes and different mandates. Historic, natural, or
undisturbed conditions may be less common in estuaries due to these cumulative historic stresses,
and the characteristic variability of estuaries can make assessments difficult. Estuarine programs
such as NEPsand National Estuarine Research Reserves (NERRs) often work with limited budgets and
staff, so the coastal approach offers guidance for simplified development and use of narrative BCGs,
as well as of quantitative BCGs.
Estuaries and coasts are, in general, less intensively monitored than streams and the BCG
implementation steps can be used to organize whatever data are available and identify gaps.
While many stream reaches can be assessed in aggregate in the context of regional condition,
estuaries and coastal systems are usually managed as unique waterbodies requiring individual
attention and many different approaches have been used in various estuaries. In order to assess
and manage these coastal systems, estuarine/coastal BCG implementation keeps the advantages of
the BCG as originally developed for streams but provides management steps and greater flexibility to
address the complexity of estuarine and coastal biology (Figure 3-3).

3. Estuarine and coastal BCG implementation
Figure 3-3. Woods Hole, MA, a complex coastal system.
Origins of the estuarine and coastal BCG
The estuarine arid coastal approach was proposed and launched at a 2005 estuarine workshop
hosted by the U.S. EPA (Office of Water and Region 1) in Providence, Rl. Concepts were developed
further at workshops in Maine during the winter of 2006 and spring of 2007. The approach was
solidified when the EPA Office of Water, Region 1, and Office of Research and Development
co-sponsored a November 2008 workshop in Narragansett, Rl, inviting many national estuarine
experts and managers (Appendix C). The goal of these efforts was to develop and refine a nationally
applicable, integrative estuarine BCG approach to enable meaningful comparisons among measures
and waterbodies. Another workshop in 2009 gathered Narragansett Bay experts and managers
(Appendix D) to begin an estuarine BCG for that area. The work has evolved and been further
refined by a standing estuarine/coastal BCG workgroup and by pilot BCG work in Mobile Bay, AL;
the Lower Columbia River, OR and WA; Greenwich Bay, Rl; and Puerto Rico coral reefs. This
document summarizes work to date on development and application of guidance for estuarine
and coastal BCG implementation and provides a basis for further work to refine, test and apply
the approach.

Implementing the Biological Condition Gradient Framework
3.2. Development of estuarme/coasta! BCG guidance
Discussions at the Narragansett workshops and afterwards led to a sequence of eleven possible steps
or actions as guidance for scientific and management groups developing and applying the BCG to an
estuarine system. To address the variety of system types and needs, each group can review the steps
and create a path that works for their specific case and may choose to apply one, several, or all of
these implementation steps. While these are presented as separate steps, groups can merge these
concepts in their actual development process. Collaborative approaches to these steps might range
from informal discussions, to expert workgroups, to hosted workshops.
Eleven useful steps - outline
The first implementation steps of the guidance (1-3) do not involve an actual BCG per se, but
apply management decision tools to involve stakeholders and evaluate environmental problems
in preparation for BCG work. In the next steps (4-7) a BCG is built to solve these problems by
developing narratives for BCG levels used for communication, engaging stakeholders, and non-
regulatory approaches including assessment of condition, goal-setting, evaluating management
alternatives, and monitoring to track progress toward goals. In the final stages (8-11) a rigorous
and quantitative BCG is developed through expert consensus to define ALU thresholds and baseline
conditions, track changes in condition, and assess effectiveness of non-regulatory and regulatory
actions. Public/stakeholder engagement and hosted workshops can be critical throughout the
process. Steps:
1.	Define problems, engage partners and stakeholders
2.	Collaborate to define management goals, visions, and objectives
3.	Determine the biological components, stressors, measures, and attributes most relevant
to management objectives
4.	Delineate and classify the waterbody and watershed of interest
5.	Organize and analyze existing data for the identified measures, collect new data if needed
6.	Define BCG level 1 conditions for the identified attributes
7.	Develop narrative descriptions of the biology expected at each BCG level as a narrative
BCG model; apply to management needs
8.	Convert narrative descriptions to quantitative metrics and thresholds, calibrate the BCG
9.	Develop a stressor gradient and stressor-response relationships
10.	Organize, interpret, and report results
11.	Develop decision support, communication, and monitoring tools; assist management partners.

3. Estuarine and coastal BCG implementation
Eleven useful steps - details
The implementation steps should not be seen as prescriptive, but rather as a series of choices that
can be selected to deliver the desired benefits of a BCG for a coastal system or estuary. Some of
these steps may already have been accomplished for some systems or may not be necessary for
certain objectives. Every coastal group using a BCG approach will have different problems,
different goals, and different solutions. The eleven steps can serve as thinking and planning
points for BCG development.
Steps 1-3; initial collaborative management for effective BCG outcomes
1.	Define problems, engage partners and stakeholders. Scientists, managers, and stakeholders
should first address fundamental questions: What are the problems to be solved? What are the
stressors of concern? Who will use or care about the results? Identifying and involving stakeholders
(including partners, state and federal agencies, communities, industry, businesses, and the public)
early in the process leads to effective application of a developed BCG later on. Well-established
management frameworks (Section 5.3, pages 44-48) including Structured Decision Making (SDM)
or Drivers-Pressures-State-Impacts-Responses (DPSIR) are effective tools for working with partners
to produce a BCG that will be used in environmental decision-making. Social Network Analysis (SNA)
is an advanced method of identifying stakeholders, connections among groups, and participation
gaps (Figure 3-4). Forming relationships with stakeholders at the start of a project can be critical,
as outlined in Steps 1, 2, and 3 of this BCG guidance.
2.	Collaborate to define management goals, visions, and objectives. What are the ecological,
economic, and social outcomes that should be achieved relative to the management problems?
What are stakeholder visions for a desired future estuary? Relative to BCG, what are the
environmental objectives? As above, these questions are best addressed in partnerships
with stakeholders, and SDM or DPSIR can be very helpful.

Implementingthe Biological Condition Gradient Framework
NH Towns
ME Towns
Conservation Commissio]
& Boards //
O Water Districts
o Planning Commissions
(3 Universities/Research Orgs.
NH State Agencies (non-DE:
UNH Depts and Centers
NH DES and
O ME State Agencies
o Federal Agencies
State Agency Partners
from Other States
'Other" Cross-Jurisdictional
/ Great Bay \
Related Projects
\ Groups /
Figure 3-4. SNA map of collaborations within the Piscataqua River Estuary Program (PREP). Partner
types are shown with different colors based on participation in past projects and collaborative groups
(gray circle). Size of the nodes and thickness of the lines are proportional to the number of organizations
and projects represented. Graphic: Kate Mulvaney
3. Determine the biological components, stressors, measures, and attributes most relevant to
management objectives. The most effective components of biology, e.g., benthos (Figure 3-5),
seagrass, saltmarsh birds, fishes, are: 1) relevant to the management objectives, 2) susceptible to
human disturbance and affected by controllable stressors, 3) ecologically important, 4) important
to stakeholders, and 5) easily assessed with effective measures (e.g., benthic IBI scores, seagrass
acres, bird diversity indices, and fish Catch Per Unit Effort (CPUE) statistics). Evaluating candidate
components/measures/attributes and their stressors may require conceptual ecological models,
examination of species lists, habitat lists, guild lists, public/stakeholder workshops, information on
ecosystem services/values, etc. In many cases, proxies or models may be used to evaluate desired
attributes that are difficult to measure; for example, structural measures such as measured depth

3. Estuarine and coastal BCG implementation
of bioturbation may be used as proxies for functional attribute processes such as benthic
biogeochemical cycling. Any application of proxies or modeled measures should explain the
logic behind this use. Final selection of measures and attributes will also depend on the data that
are available for each, as described in Step 5 below. Measures are organized into the BCG estuarine/
coastal attributes described in Table 4-1 (page 23). This last step is critical because the narrative
descriptions used to consistently assign BCG levels are tied to specific attributes.
4*	i
% *
Figure 3-5. Estuarine benthic invertebrates, often the basis of estuarine assessment.
Scale shows one centimeter.
Steps 4-7: A narrative BCG model to identify and communicate condition,
develop visions, set goals and targets, and motivate stakeholders
4.	Delineate and classify the waterbody and watershed of interest. Bounding the research area
will streamline and improve this and later work. The estuary or area of interest should be defined,
identifying landward and seaward boundaries. The watershed of the estuary should also be
delineated. Areas of heightened interest should be identified, and a variety of spatial tools are
available to assist with all these tasks. Classifying the systems into types of estuaries lets managers
make comparisons among similar systems, including comparisons of methods to determine
undisturbed or minimally disturbed conditions. Classifications can also address specific issues
including conservation status or nutrient susceptibility. Within a waterbody, classification by
substrate, salinity, habitat, or other factors can reduce apparent natural variability in biological
data by grouping analyses within ecologically relevant types. Classification improves the BCG process
and clarifies links to stressors. Many established classification schemes exist for various purposes,
and this is covered in Section 5.1 (pages 39-42).
5.	Organize and analyze existing data for the identified measures, collect new data if needed.
Practitioners might consider three actions for each of the measures identified in Step 3 above:

Implementing the Biological Condition Gradient Framework
-	Identify the spatial and temporal coverages that are required to answer the scientific
and management questions, identify existing data, identify data gaps, and determine if
new data collection is advisable.
-	Develop data acceptance criteria (for existing data) and/or sampling design (for new
data). If helpful, texts and resources are available to assist with sampling design,
including Gibson et al. (2000) and U.S. EPA (2002).
-	As appropriate, if new data are required, define sample collection, sample processing,
data management, and Data Quality Objectives (U.S. EPA 2006b).
Different estuarine systems have been studied in various ways, and the types of data that exist in
each differ widely. For some estuaries, the type, quantity, quality, and organization of existing and
available data on biology and on stressors will be excellent. For many estuaries, some data will be
available but a considerable effort will need to be invested in finding, deciphering, and organizing
these data. Other estuaries will be relatively unstudied, and basic assessments may need to be
conducted. For every estuary, it is important to evaluate the types of data that exist, the resources
that are available to collect new data, and the types of new data that would be most useful
(Figure 3-6).
Figure 3-6. Scientists collecting the new data required to construct a coral reef BCG, southwestern PR.
6. Define BCG level 1 conditions for the identified attributes. An important element of BCG
development is that assessment is consistently linked to natural or undisturbed condition as level 1.
This reference is anchored to reduce problems associated with "shifting baselines" (Pauly 1995),
where what is perceived as 'good' condition declines over decades as humans collectively forget what
was 'good' 50 years ago. Methods to define this level 1 anchor are discussed in detail in Section 4.2

3. Estuarine and coastal BCG implementation
(pages 29-35). Conceptually, an undisturbed baseline will relate to both biological condition and
stressor levels and so can be identified in several ways. An undisturbed coastal or estuarine condition
can be defined as a biological state through structural or functional descriptors, as an ecological
narrative, as a time period, as a stressor level, or in some other manner. Undisturbed or natural
condition should be described as accurately as possible for each assessed waterbody, but methods
to determine an undisturbed state will differ among waterbodies depending on the data that are
available, on the local history of development, and on other factors. In some cases, level 1 cannot
be well defined, and levels 1 and 2 conditions are combined to describe an undisturbed/minimally
disturbed baseline. In all cases, baseline conditions can be defined by assembling panels of experts
to find consensus on biological conditions that would be expected in a waterbody under undisturbed
conditions given the data that are available.
7. Develop narrative descriptions of the biology expected at each BCG level as a narrative BCG
model; apply to management needs. Once level 1 is defined, narrative or conceptual descriptions
of expected biological structure, condition, and function at levels 2 through 6 can be developed for
each of the identified attributes. For consistency among BCG efforts in different areas, BCG narrative
for different levels should follow established level descriptions for each attribute. For estuaries and
coasts, see Table 4-2 (pages 30-31). These narratives were adapted from those developed and
tested in streams (U.S. EPA [2016], Tables A-l and A-2 of this document). Building on Table 4-2,
developing more specific narrative descriptions for each attribute in a particular waterbody better
defines the biology characterizing BCG levels. These level descriptions are a narrative BCG model
that assigns BCG levels to observed biology. Adding a Generalized Stress Axis (e.g., human
population, year for a historical BCG) would add value and context (see step 9 below).
Hosted workshops, panels of invited experts, or expert workgroups have been a successful approach
to develop these specific narratives. The basic process is formalized as BCG calibration in Step 8
below. Experts should be well prepared before the workshop, should arrive already familiar with the
basic concepts of BCG, and should have a clear vision of workshop expectations. Pre-analysis of data
can assist in this process. For example, in streams, biotic assemblage data were analyzed with
stressor data to produce empirically derived high stress and low stress indicator taxa; these data
were brought to the workshop and compared to expert conception of high and low stress indicator
taxa. In developing a BCG for coral reefs, experts were presented with a selection of representative
unlabeled photos and videos collected along a condition gradient, which helped facilitate discussion
and consensus. The descriptions of coral condition at each level were then used effectively in reef
evaluation and goal setting (Bradley et al. 2014). The essential elements of BCG calibration (Step 8
below) were used to develop this BCG model.
In the coral reef example above, a narrative BCG was used for assessment and for setting goals and
targets. A narrative BCG is an effective tool for public communication and can support a variety of
management needs. For non-regulatory approaches a narrative BCG can take management groups
through the entire process of engaging stakeholders, describing past and present conditions,
developing a vision for a desired future estuary, defining management goals and targets, evaluating
possible actions, and monitoring progress towards targets.

Implementing the Biological Condition Gradient Framework
Steps 8-11: A fully developed BCG model to support both regulatory
and non-regulatory needs
8. Convert narrative descriptions to quantitative metrics and thresholds, calibrate the BCG.
Building on narrative descriptions of the selected measures, numeric metrics (e.g., IBI scores, acres
of habitat, density of valued species) can be developed to better define thresholds between levels.
This can improve the ability of a narrative BCG to set numeric targets, track progress, prioritize
actions, refine stressor-response relationships, or support CWA regulations.
The BCG is calibrated when expert workgroups use consistent BCG level guidelines (Table 4-2) and
a consensus process to develop decision rules for assigning thresholds to BCG levels, then test these
rules with data and modify as needed. A narrative non-regulatory BCG model can and should be
calibrated, but a model intended to support CWA and other regulations must be quantitative,
rigorous, based on sufficient data and well-calibrated with the required testing and iteration.
U.S. EPA (2016) provides a
detailed, tested, and well-
established calibration
process for convening
experts, using scientific
consensus with available
data (e.g., stressor-
response relationships from
monitoring programs),
calibrating the BCG, and
assigning biological metric
scores to BCG levels (U.S.
EPA 2016). Figure 3-7
outlines the steps in
calibrating a BCG for
quantitative or regulatory
use by states, tribes,
territories, and counties in
supporting CWA and other
BCG Calibration
Step 1
Assemble data
Step 2
Analyze and prepare data
Step 3
Convene expert panel
Step 4
Develop decision model
Step 5
Test and
review model:
Calibrated BCG model with
quantitative decision rules for
assigning sample sites to BCG levels
Figure 3-7. Steps for calibration of a quantitative BCG. Graphic: U.S. EPA 2016

3. Estuarine and coastal BCG implementation
In Step 1 of calibration, data are assembled to cover the full range of condition and stress within one
or more estuaries or coastal settings. Calibration for regulatory application requires sufficient high-
quality data. In Step 2, these data are processed to describe stressor-response relationships, and
are put in a format that is useable by workshop participants. Step 3 (identifying and inviting an
appropriate range of experts) is critical to the success of the project because in Step 4 these experts
will use the data to develop a quantitative BCG, i.e., numeric decision rules for BCG levels in selected
attributes. In Step 5, the quantitative model and process are tested against data and recalibrated
until the BCG is consistent, scientifically defensible, transparent, well-documented, and ready for
use in CWA decision-making or other regulatory and non-regulatory applications. At this point,
the decision rules can be applied into the future without further consulting the expert panel.
These calibration steps were designed for development of BCG models for regulatory application
under the CWA and rely on quantitative data, but most estuarine or coastal BCG models are
developed by non-regulatory programs such as NEPs, and are not intended as a basis for regulation.
Further, the sparse data typical of estuaries may not be sufficient to support calibration and testing
for CWA decisions. However, the expert workgroup process described above improves any BCG
model, even when extensive testing and iteration are not possible. As before, coral reef BCG
practitioners used this expert calibration process with narrative descriptions of coral condition
to create a much-needed management tool. Expert panels are a central element in developing
any BCG model.
9. Develop a stressor gradient and stressor-response relationships. The Generalized Stress Axis
(GSA, the BCG x-axis of Figure 2-2, page 6) aggregates stressors on the assumption that biology
(the y-axis) responds to the cumulative impacts of all stressors (see U.S. EPA 2016, Chapter 5).
Anthropogenic stress to the estuary can be considered in general terms to address many BCG goals,
and better characterizations of GSA stressors may include human population numbers, loadings
from point sources, ambient pollutant levels, or time, as a surrogate for increasing anthropogenic
stress. An analysis of changes in land-use patterns in the estuarine watershed over time (e.g.,
changes in percent of impervious surface) or use of a landscape development index (Oliver et al.
2011) or other watershed index may be an effective tool for improving a generalized stressor
gradient. Many estuarine and coastal impacts are based on stressors within the watershed,
e.g., nutrient or sediment loads.
A stress gradient that identifies individual stressors allows development of specific thresholds
for these stressors and so leads to a more effective BCG. Diagnostics and control of stressors
may involve more detailed stressor characterization and additional analysis using specific
stressor-response data sets and diagnostic tools such as stressor identification and causal analysis
(www.epa.gov/rps/stressor-indicators, www3.epa.gov/caddis). Specific stressor-response models
linking stressor levels to BCG condition are extremely valuable for stressor control.
Oceanic stressors may also play a significant role (Figure 3-8). Temperature changes and rising sea
levels are stressors that influence biotic distribution and condition. If these larger-scale stressors
are not considered, local restoration (e.g., of saltmarshes) may not be effective. To best relate all
biological and stressor measures to a common anchor point, programs can include undisturbed
stressor levels in the definition of reference condition. Also, the human-caused component of

Implementingthe Biological Condition Gradient Framework
stressors should be separated from natural stressor variability. In many cases, for the more widely-
used indices, basic stressor-response relationships for the assessment measures will already have
been developed through established monitoring programs or through the published literature.
In other cases, e.g. measures of function and connectance, stressor-response relationships may be
estuary-specific and may need more development. In all cases, a stressor gradient that associates
biological condition with individual stressors is critical for managing specific stressors.
Figure 3-8. Oceanic influence near the mouth of Narragansett Bay, Rl.
10. Organize, interpret and report results. BCG attribute levels and a GSA can be organized as a
BCG model to evaluate environmental data and communicate estuarine condition in a meaningful
way. Analyses may focus on specific areas or on the entire waterbody to reveal what the overall
condition of the estuary is, which biotic components of the estuary are doing well, what the
significant biological problems are, what specific locations within the estuary are doing well
(or poorly), and how that estuary is faring in comparison to other estuaries. Stressor-response
linkages to biological condition can be reported for the GSA and for specific manageable
Data should be presented in ways that the public can easily understand and relate to. Although not
conducted using a BCG, the Chesapeake Bay Program provides helpful examples of data presentation,
having worked with the issues of summarizing multiple assemblages at multiple scales. They report

3. Estuarine and coastal BCG implementation
data at the embayment level, whole-bay and watershed level. Various measures are examined
separately, and averages are combined into an overall health index. The experiences of Chesapeake
Bay (and of other estuaries with long-term data such as Buzzards Bay or Tampa Bay) are useful
models for data presentation (See Appendix B, FAQsheet). Many of these analyses focus on the
relationship of the parts to the whole, e.g., evaluating the overall current condition of estuaries
relative to the condition of estuarine components, and relative to the conditions of the past.
11. Develop decision support, communication, and monitoring tools; assist management partners.
Work in pilot systems provides several excellent examples of applying BCG to management, and
Section 6 (pages 61-84) describes these efforts in detail. Different uses of BCG can be explored
to meet the objectives of each program:
•	Explicitly incorporating biology into estuarine and coastal management for greater public appeal
and for better addressing both cumulative impacts and specific stressors.
•	Using scientific and stakeholder consensus to improve interpretation of assessment and develop
environmental visions, goals, and targets. This can benefit National Estuary Program (NEP)
management plans; assist National Estuarine Research Reserve (NERR) programs (Figure 3-9),
Non-Governmental Organizations (NGOs) and other self-motivated stakeholders.
•	Communicating conditions, goals, progress towards goals, and other aspects of ecology and
management. Different forms of communication are usually needed to reach a wide range
of audiences and stakeholders. A motivated public can contribute to environmental success
in many ways, e.g., reducing inputs from lawns or generating political will.
•	Organizing and reporting results from existing monitoring programs; this improves assessments
of environmental conditions both nationally and locally.
•	Supporting CWA and other regulatory goals for environmental action by states, tribes, territories,
counties, and federal agencies. Regulatory goal-setting requires a rigorous calibrated BCG-
these goals are usually subject to a higher level of scrutiny than are the non-regulatory goals
described above.

Implementing the Biological Condition Gradient Framework
Figure 3-9. Taskinas Creek, part of the Chesapeake Bay NERR in Virginia. Photo: April Bahen,
As above, applying the coastal and estuarine BCG guidance can allow better assessment, goal-setting,
monitoring, and communication/reporting. It can also contribute to refinement of designated uses
so they are directly linked to biological measures. The guidance can be used to improve biological
criteria for management of nutrient inputs, assess the overall condition of the waterbody for better
communication, prioritize local land-planning decisions, interpret national monitoring programs,
communicate a need for protection of nature, or set numeric targets in a way the public can easily
The focus of the BCG approach is on developing the scientific underpinnings needed to assign BCG
level numbers to biological conditions. The issues of determining what conditions are or are not
acceptable for a specific waterbody are management questions, informed by BCG levels, but decided
through a process that considers public and stakeholder interests, environmental regulation,
ecological goals, and societal goals. NEPs and similar management groups are well positioned to
take BCG through the entire process, from initial stakeholder investment to BCG development
to stakeholder involvement in setting and achieving specific goals and targets.

4. Components of the estuarine/coastal BCG
4, Components of the estuarine/coastal BCG
4.1. Attributes and measures
How and Why Do We Group Biological Responses?
Biology responds to stressors in predictable ways that can be divided into types of response. Here we use
changes in structure; non-native taxa, condition, function, and conneciance as five meaningful groupings
of biological response, termed 'attributes' in the BCG approach. This is important because attributes respond
differently to stressors; increasing stress may affect species composition (structure} before it affects
bioturbation (function). Assigning levels of biological condition within attributes improves resolution
and consistency.
This BCG approach organizes important estuarine and coastal biological responses into ecological
attributes (Table 4-1). This table serves as a guide for a wide range of applications, is designed to be
useful at multiple spatial scales, and incorporates a variety of biological and ecological measures.
The stream attributes (see Appendix A, also U.S. EPA 2016) were used as the foundation for the table,
but were adapted to include estuarine and coastal features.
Table 4-1. Five attributes and potential measures for application to estuarine and coastal BCGs at different
scales, developed through expert consensus at a 2008 BCG workshop. This table provides an ecological
organization of measures but does not include all relevant measures and does not provide specific direction on
which ones to use in a given waterbody. Attribute and measure selection needs to consider the management
questions, the important stressors, and the data that exist or that can realistically be collected.
Potential Measures and Description
Measures of waterbody, community, or habitat structure and complexity, also recognizing loss of
habitats or species due to human activities
Examples include macroinvertebrate or fish indices, phytoplankton or zooplankton community
measures, epifaunal measures, biotope mosaics, presence/quantity of sensitive or susceptible taxa or
biotopes, measures of seagrass or macroalgae
Measures of non-native species, including intentionally introduced species
May include measures of the impact of introduced and non-native species
Examples include estimated numbers of species or individuals, biomass measures of natives and
non-natives, or replacements of native species
Measures of the condition ('health') of waterbodies, habitats, or species. Also includes measures of
Examples include harmful algal blooms, disease outbreaks, outbreaks of other harmful taxa, measures
of habitat or biotope health such as seagrass condition or wetland condition, fish pathology or shellfish
bed condition, measures of reproductive success
Measures of energy flow, trophic linkages, and material cycling, including proxy or snapshot measures
that correlate to functional measures
Examples include photosynthesis:respiration ratios, benthic:pelagic production rates, chlorophyll a
concentrations, benthic bioturbation, and form/extent of primary production
Measures of exchanges, movements, predation, migrations or recruitment of biota between
watersheds, waterbodies or habitats; measures may be strongly affected by factors adjacent to or
larger than the immediate study area
Proxies may be used as measures, including habitat landscape metrics, biological watershed inputs,
anadromous fish data, or hydrological measures

Implementing the Biological Condition Gradient Framework
Three basic attributes
The structure, non-native taxa, and condition attributes are often used in building BCG models.
These attributes are ecologically important, meaningful to stakeholders, and relatively easy to
measure. The structure attribute can be applied to almost all BCGs, and measures of these three
attributes can also serve as proxies for function and connectance.
The estuarine/coastal 'structure' attribute described in Table 4-1 considers structural patterns of
biology at several scales including community structure (e.g., IBIs and other measures), habitat
structure (e.g., patterns of primary and secondary production within seagrass beds), or waterbody
structure (e.g., numeric analyses of the mosaic of living habitats [biotopes] within the waterbody).
This attribute may further include biological features at the watershed scale (e.g., landscape measures
of terrestrial biology to evaluate the living watershed/waterbody complex).
Figure 4-1. Seagrass is a biotope and a sensitive indicator of condition.
Channel Islands National Marine Sanctuary, CA. Photo: NOAA
Non-native taxa
The coastal/estuarine 'non-native taxa' attribute evaluates the populations of invasive species in a
waterbody and their effects on native species. This is essentially identical to the stream non-native
taxa attribute, although different species are involved (Figure 4-2).

4. Components of the estuarine/coastal BCG
Figure 4-2. Non-native taxa: dead man's fingers (Codium fragile), a branching green seaweed, was first
seen in the U.S. in 1957 and has spread extensively since then. Codium displaces seagrasses, kelp, and
other native flora. Codium has washed up on shores in Massachusetts in such large quantities that beaches
have had to be closed to the public (Donohue 2006).
The estuarine 'condition' attribute mirrors the stream condition attribute in evaluating the anatomical
or physiological characteristics of an organism through disease, tumors, and deformities, but the
estuarine version may also consider ecological condition of a larger habitat or area. Coastal or
estuarine condition measures include coral or seagrass disease, multi-metric saltmarsh condition
indices, or outbreaks of destructive native taxa (e.g., predatory native urchins or starfish).
Higher-level attributes
In general, measures of biological structure, non-native taxa, and condition (described above) are
more available than measures of biological function and connectance as described below (Davies
and Jackson 2006). Yet, these higher attributes may better address concepts of sustainability and
resilience, and may help identify and predict critical ecosystem shifts and tipping points such as
system-level anoxia or coral reef loss. Some effective functional measures have been developed,
often based on surrogates or proxies. Structural measures may serve as proxies for function and
connectance when logic and assumptions are clearly explained.

Implementing the Biological Condition Gradient Framework
The 'function' attribute is very similar in both stream and coastal/estuarine BCGs. Both evaluate
ecosystem processes including primary production, respiration, and benthic biological exchange,
also, both use the evidence of structural proxies as measures of functions. To illustrate, the Southern
California Coastal Water Research Project (SCCWRP) and collaborators have developed a macroalgal
biomass measure for California coastal lagoons that indicates major shifts in ecological condition and
function (Sutula et al. 2014). Macroalgal biomass was linked to bioturbation depth (measured with a
sediment profile camera, Figure 4-3) which served as the more direct proxy for evaluating ecological
condition and functional shifts.
Figure 4-3. Sediment profile image showing shells on the sediment surface and a 15 cm deep section of
the sediment below the shelly surface. The light brown or reddish area nearest to the sediment surface
has been oxidized by the activities of burrowing animals. The depth of this area is an approximation of
benthic bioturbation, which controls many sediment processing rates and is a structural proxy for function.
The large brown vertical sediment disturbance just right of center is evidence of tunneling by a larger
benthic creature, likely a mantis shrimp (Squilla empusa) as they are abundant in this part of the Taunton
River (MA).
Other potential measures or proxies of function include system metabolism, form and quantity of
primary production, and sediment biogeochemical processing rates. Metrics quantifying changes
to the extent, proportion, and distribution of biotopes (living habitats) in an estuary or other area
(the biotope mosaic approach, see Section 5.4.1.C on pages 51-53) are structural proxies for function

4. Components of the estuarine/coastal BCG
at a larger scale: each biotope provides a unique set of functions, so when the mix of biotopes is
changed from the undisturbed condition, so too is the overall function of the waterbody. When high
functioning naturally-occurring biotopes (e.g., oyster reefs) are replaced with low functioning biotopes
(e.g., shell hash with small tube-building fauna), the overall function and biological condition of the
waterbody will be diminished-and this is a concept that engages public sentiment.
'Connectance' in estuaries occurs more broadly than in streams: estuaries are not linear, and water
movements are multi-directional. Connectance in estuaries, coastal habitats, and coral reefs includes
habitat exchanges (Figure 6-18, page 78), linkages within the estuary, and connections to streams,
coastal waters, and watersheds or watershed integrity. Proxies may include abundance of
anadromous or catadromous fishes (e.g., eels, salmon, and herring) or other taxa known to
depend on habitat connections.
Biological watershed inputs (e.g. phytoplankton chlorophyll o, prey species, salt-tolerant freshwater
taxa) may be used as proxies for watershed connectance. Within-estuary connectance can be
evaluated through spatial analyses of biotope mosaics, e.g., measures of landscape structural
connectedness, isolation, or fragmentation (Rutledge 2003). Similarly, hydrologic data (e.g., effects
of dams, culverts, causeways) when combined with biological data can be used as surrogates
for connectance (Figure 4-4).
Figure 4-4. Hydrological evidence for poor connectance-Watchemoket Cove, Rl, is connected to
Narragansett Bay only under a small bridge on an old railroad causeway.
The coastal and estuarine BCG adaptation does not use stream attribute IX (spatial and temporal
extent of detrimental effects). Draft narratives for all estuarine attributes follow U.S. EPA (2016)
stream narratives (Appendix A) to allow comparability in level assignments among BCG approaches
in different types of waterbodies.

Implementing the Biological Condition Gradient Framework
New methods
Moving forward, advanced new sampling technologies and analysis tools will lead to new or improved
measures to characterize the informative attributes of function and connectance. Evaluating and
monitoring coastal and estuarine systems can be difficult due to high levels of complexity and
variability. Yet, innovative remote sensing technologies (including acoustic imaging, aerial
photography, underwater still and video imagery, autonomous underwater vehicles [AUVs],
and satellite imagery) are now available for acquiring large amounts of data.
Satellite ocean color data (such as that previously provided by the Hyperspectral Imager for the
Coastal Ocean [HICO] on the International Space Station) offer high quality spectral data at global
scales and high spatial resolutions (Figure 4-5). While the HICO hyperspectral sensor with 90 m pixels
was damaged in a solar storm, other orbiting sensor platforms are currently providing multispectral
data (e.g., Operational Land Imager with 30 m pixels, Ocean and Land Color Instrument with 300 m
pixels). Several other hyperspectral sensors are planned for the future with 2020 and later launch
dates. Satellite remote sensing presents opportunities to link anthropogenic stressors to biological
responses in coastal and inland waters. EPA is developing spectral algorithms that better determine
chlorophyll levels, biological productivity (e.g., plankton blooms), and other water quality measures
in coastal waters. These could serve as proxies for BCG attributes of function and connectance.
While these developing technologies may enhance our
ability to better characterize and manage estuarine and
coastal resources, no single sampling method or tool
can successfully address all attributes relevant to a
waterbody. Incorporating several measures at
multiple scales in a BCG leads to a more comprehensive
understanding of condition, which should improve the
ability to engage the public, to set and track meaningful
environmental goals, and to understand the dynamic
conditions that exist within coastal waters. BCG is a way
to bring different attributes and lines of evidence together
with academic and scientific expertise to evaluate large
systems, e.g., the managed waterbody and its associated
watershed and coastal or oceanic systems.
Figure 4-5. HICO satellite image of the Columbia River, OR and WA. Image: HICO image gallery:
http://hico.coas.oregonstate.edu/gallery/gallery-scenes.php, accessed 5-23-2016

4. Components of the estuarine/coastal BCG
Once attributes and measures have been selected and the necessary data have been acquired, the
BCG is assembled by assigning narrative or numeric thresholds and decision rules for levels 1 through
6 for each measure. This will usually occur in separate stages of effort. The key to this process is the
consistent guidance of Table 4-2, which provides narrative to define all six levels for each estuarine/
coastal BCG attribute. Table 4-2 was developed through a panel of national estuarine experts at the
2008 BCG workshop (Appendix C), and the first two columns of Table 4-2 ('Attributes' and 'Potential
Measures') are identical to those in Table 4-1 (page 23). The six 'Examples of BCG Level Narratives'
columns present a flexible set of estuarine and coastal narratives that are closely aligned with stream
narratives (U.S. EPA 2016, Appendix A of this document), but have been modified to include estuarine
aspects including complexity, biotopes, and estuarine taxa.
The strength of the estuarine and coastal BCG level narratives as shown in Table 4-2 is their
consistency with the accepted freshwater level narratives. Level 2 in a Midwest stream should have
the same basic ecological meaning as level 2 in a Florida lagoon. BCG levels 1-6 provide a common
language for assessment because the methods and the narratives can be applied whenever a full
range of biological condition can be described using any characteristic of biology. Applications in
different estuaries will include different measures; the measure-specific narratives of Table 4-2 are
put forth as examples that could be modified for use with different approaches and measures. All
measures and narratives of this Table can be adapted as needed. Further, levels can be compressed
or eliminated as dictated by the available data or by management needs, e.g., combining levels 1 & 2,
3 & 4, and 5 & 6 as three units of reporting. Each estuarine or coastal BCG program should consider
their own uses of Table 4-2, but the basic guidelines provided by the freshwater stream narratives
should be followed. The left column of Figure 2-2 (the BCG conceptual model, page 6) shows stream
narratives applicable to all attributes, and Appendix A provides stream narratives for each individual
attribute. These narratives are discussed in U.S. EPA (2016).

Implementing the Biological Condition Gradient Framework
Table 4-2. Attributes and potential measures developed at the 2008 Estuarine BCG workshop
(left two columns) paired with examples of narratives for BCG levels (right 6 columns).

Examples of Estuarine BCG level Narratives, based on recommendations of a panel of experts
Potential Measures

and U.S. EPA (2016)

and Descriptions
Level 1
Level 2
Level 3
Level 4
Level 5
Level 6

Measures of waterbody,
Community or
Evident changes in
Most sensitive, large
Sensitive, large

community, or habitat
changes in
biological measures;
changes in
and/or long-lived
and/or long-lived

(i.e., biotope) structure
composition is
decreases in
taxa are absent, with
taxa are largely

and compositional
as naturally
sensitive species or
a dominance in
absent with

complexity; may also
occurs except
of biotopes,
biotopes and
marked decreases
abundance of

recognize loss of biotopes
for global
patterns of
increases in tolerant
in sensitive
tolerant taxa;
extremes in

or species due to human
species or biotopes;
species, including
significant shifts in
abundance of

patterns of
evident changes in
large or long-lived
species diversity, size
remaining taxa;

or other
patterns of primary
taxa; increases in
and densities of
marked shifts in

Examples include
producers and
tolerant species.
remaining species;
diversity, sizes,

macroinvertebrate or fish
biotope mosaic
estuarine biotope
Evident changes
patterns of primary
and densities of
indices, phytoplankton or
measures, and
changes in
in patterns of
producers and

zooplankton community
communities or

estuarine biotope
species; near

measures, epifaunal
areas with large,
of sensitive

producers and
mosaics significantly
complete loss or

measures, biotope mosaic
long-lived and
ortolera nt

estuarine biotope
altered; many
alteration of

measures, and presence,
sensitive species
species or

mosaics, which
sensitive natural
estuarine biotope

quantity, orarrangement
or biotopes are

are altered with
biotopes lost with
mosaic; marked

of sensitive taxa or
as naturally

replacement of
replacement by
losses in natural

biotopes, including large

natural biotopes
tolerant or non-
biotope area

long-lived benthic species,

by tolerant or
naturally occurring

seagrass, coral reefs,

non-natu rally

macroalgae, orwetland




Status of non-native
Non-native taxa,
Non-native taxa may
Some assemblages
Same as level 5

species. May include
if present, do
be prominent in
abundance of
(e.g., benthic

measures of the impact of
not significantly
may be
some assemblages
tolerant non-
invertebrates, algae,

invasive and non-native
reduce native
present, but
(e.g., benthic
native species;
biva Ives,

taxa or alter
crustaceans, fishes,

structural or
has a non-
crustaceans, algae,
prominent in
epifauna) are

Examples include
bivalves, fishes);
dominated by

estimated numbers of
species or individuals,
relative densities or
biomass measures of
natives and non-natives,
or replacements of native
effect on
some sensitive
native taxa may be
reduced or replaced
by functionally
equivalent non-
native species
tolerant and/or
invasive non-native

Measures of the condition
Same as
Incidences of
Incidences of
Incidences of
Diseases, harmful

of waterbodies, biotopes,
harmful algal
level 1
diseases, harmful
diseases, harmful
diseases, blooms,
algal blooms, and

communities, populations,
blooms, other

algal blooms, and
algal blooms, and
and other outbreaks
other outbreaks

ororganisms. Some
outbreaks of

other outbreaks may
other outbreaks
are increasingly
are common and

measures may serve as
harmful taxa,

be slightly higher
are slightly higher
serious, biotope

proxies for resiliency.
and biotope or

than expected;
than expected
particularly affecting
or community


biotope or
(e.g., coral
long-lived taxa

Examples include harmful
measures are

bleaching events
where biomass may
measures are
algal blooms, disease
consistent with

measures may be
also be reduced, e.g.,
extremely low,
outbreaks, outbreaks of

slightly lowerthan
and result in
coral bleaching

harmful native taxa (e.g.,

slightly elevated
events are frequent
outbreaks, etc.

starfish), fish pathology,
incidents and

mortality), and
and result in
may occur across

and measures of specific

other indices are
mortality. Other

biotopes orcommunities,

slightly lowerthan
indices are

e.g., indices of

significantly lower

invertebrate, coral,

than expected
taxa groups, or

wetland, or shellfish bed




4. Components of the estuarine/coastal BCG
Table 4-2. (continued)
Potential Measures
Examples of BCG Level Narratives, based on recommendations of a panel of experts and U.S. EPA (2016)

and Description
Level 1
Level 2
Level 3
Level 4
Level 5
Level 6

Measures of energy flow,
Energy flows,
Energy flows,
Virtually all
Most functions
Losses of some
Vlost functions

trophic linkages and
material cycling,
functions are
are maintained
show extensive

material cycling, including
and other
cycling, and
maintained through
and persistent

proxy or snapshot
functions are as
are manifested as

structural metrics that
naturally occur,
functions are
redundant system
redundant system
changed export or
including shifts in

correlate to functional
within the
attributes. Minimal
attributes, though
import of
primary pro-

characterized by
natural range
changes to export
evidence shows
resources, changes
duction, microbial

of va riability;
and other indicative
loss of efficiency
in energy and
dominance, fewer

Examples include
interactions and
functions. Some
or complexity,
material processing
and shorter-
production: respiration
trophic links
by complex
functions (e.g.,
and some
rates, production:
length trophic

ratios, benthic:pelagic
supporting large,
functional rates
respiration ratios,
links and highly

production ratios, extent
and trophic
may shift
benthic: pelagic
simplified trophic

of benthic bioturbation,
respiration) may

production ratios,
structure, marked

export rates, and

have increased

or respiration/
shifts in benthic:

form/extent of primary

large, long-
due to organic


production, e.g.,

pollution or low

production ratios

chlorophyll a concentra-

levels of disturbance

and in energy and

tions, macroalgal



processing rates

Measures of exchanges,
System is
Same as
Slight loss, or
Some loss, or
Significant loss or
For many groups,

movements, predation,
level 1
increase, in
increase, in
increase in
a complete loss

migrations, or
connected or

(or maximum

recruitment of biota
disconnected1" in

increase) in

between watersheds,
space and time -


waterbodies, or habitats.

waterbodies, or
waterbodies, or
connectance in at

Measures within the area

habitats, but
habitats, but
waterbodies, or
least one

being studied may be

habitats is evident;
dimension (either

strongly affected by
migrations, or

sources, refugia,
sources, refugia,
spatially or

factors adjacent to or

and other
and other
pathways and

larger than the immediate

mechanisms mostly

study area.

prevent complete
sources do not
reproductive or

waterbodies, or

disconnects or
exist for some

Structural measures may
habitats are as

biotopes ortaxa;
success and

be used as proxies,

some near-
prevents (orfuMy
including hydrological


metrics, presence of dams

disconnects or

or causeways, biotope
* Note that some

connects exist;

landscape metrics such as
systems are

predation, or

fragmentation or nearest-
naturally closed

reductions in highly

off, and this is


biological watershed
the Level 1 state


inputs, orcharacteristic

waterbodies, or

migratory species, e.g.,


anadromous or

Disconnects or


otherfailures are


frequent. Most



biotopes are

Defining BCG level 1:
The BCG is anchored in level 1 as natural or undisturbed conditions. This ties back to the CWA
requirement to protect the biological integrity of waterbodies, and the Frey (1977) definition of
biological integrity as grounded in natural condition. Quantitative data representing natural
conditions exist in some locations for some measures. In the absence of these data, narrative
descriptions from historic records prior to significant human influence (and other methods) may be
applied (Table 4-3).

Implementingthe Biological Condition Gradient Framework
Figure 4-6. Thicket of Acropora cervicornis (staghorn coral) and reef fish indicative of coral reef BCG
levels 1 and 2, very good to excellent conditions. Photograph from 1975, Florida Keys, FL.
In practice, four basic methods can be considered for determination of level 1 (or combined level 1
and 2) conditions, based on Gibson et al. (2000): use of historical data, use of current data from
'reference' areas, use of predictive models, and use of expert consensus. Each method has strengths
and weaknesses (Table 4-3), and is discussed further below. These methods can also be combined.
Table 4-3. Strengths and weaknesses of various methods used to determine undisturbed or
minimally disturbed conditions (Table 4-1 from Gibson et al. 2000).

Historical Data
Predictive Models
Expert Consensus

Yields actual
Yields obtainable,
When sufficient
Relatively inexpensive.

best present status.
data are not

information on

Can be better applied

to biological

Any assemblages or

assemblages than
Inexpensive to
Work well for water
deemed important

can be used.

Common sense and
experience can be

Data might be
Even best sites
Community and
May be qualitative

subject to human
ecosystem models
descriptions of "ideal"

not always reliable.

Studies likely

were designed
Degraded sites might
Experts might be
for different
lower subsequent
beyond known data
purposes: data
and relationships is

might be



Can be expensive.

Human impacts
present in
historical times


4. Components of the estuarine/coastal BCG
Historical data
Historical data have been used to describe undisturbed or minimally disturbed conditions in a
number of U.S. estuaries. The Chesapeake Bay Program set many conservation and restoration
goals on historic baselines, using 1994 for oysters and the 1930s for seagrass (CBP 2000). Seagrass
is frequently used as an indicator of historic conditions because early charts, records, or photographs
often show seagrass and because of its sensitivity and value (Figure 4-7). Historic conditions and
subsequent changes over time were also described for Greenwich Bay, Rhode Island (Pesch et al.
2012, Shumchenia et al. 2015). The Buzzards Bay Coalition compared biological data to a historical
baseline of pre-colonial conditions. The Lower Columbia Estuary Partnership (LCEP) used historical
habitat conditions (the 1870s) as a baseline to set targets for habitat acreage to restore historic
habitat diversity (LCEP 2012). Similarly, the Tampa Bay Estuary Program identified 1900 as minimally
disturbed conditions for bay habitats, and used historical conditions of 1950 as acreage targets both
for restoring seagrass and for restoring the historical balance (proportions) of multiple habitats in the
estuary (Greening and Janicki 2006, Cicchetti and Greening 2011). In Puget Sound, historical baselines
from the 19th century were incorporated into management of wetlands, bald eagles and resident killer
whales (Samhouri et al. 2011). Historical data can correct the misinterpretation of "natural"
conditions caused by shifting baselines, and have a solid track record in representing undisturbed
conditions for estuarine and coastal management.
Figure 4-7. Seagrass with barracuda.

Implementing the Biological Condition Gradient Framework
Current reference data
Present day biology in areas believed to reflect least disturbed reference conditions is also regularly
used to develop baselines, especially when applying indices of biological condition to distinguish
between unimpaired and impaired condition. Use of reference sites to define reference condition
is the preferred technique for setting baseline conditions in the U.S. as well as in areas managed by
the European Union (EU) (EC 2002). However, present day best condition may already be significantly
degraded from natural, and shifting baselines of human perception can obscure this. Best existing
reference may represent a range from undisturbed to minimally or moderately disturbed, so defining
the quality and meaning of the reference condition is important (Stoddard 2006), particularly for use
in BCG. In severely degraded estuaries, relatively unimpaired areas in a similarly classified estuary
may be used as a surrogate measure. Data from existing reference areas have been used extensively
in the Chesapeake Bay Program, sometimes supplemented by use of best professional judgment
(Weisberg et al. 1997). In BCG developments to date, expert panels have assigned present-day
reference sites to BCG levels 2, 3, and 4, reflecting opinions that the reference sites have been
exposed to some degree of disturbance. While subject to changes in natural stressors, BCG level 1
is considered anthropogenically unstressed. This is equivalent to the 'Biological Integrity Reference'
(Stoddard etal. 2006).
Predictive models
Predictive models have often been used in freshwater systems to approximate biological condition
in the absence of environmental impact (Hawkins et al. 2000). These methods, however, have not
been widely tested or used to assign minimally disturbed conditions in estuaries and near coastal
waters either in Europe (Muxika et al. 2007) or in the United States, although see 'combined
approaches' on the next page. This is an area in need of further development and evaluation.
Expert consensus
Expert consensus, panels of experts, or expert workshops can be used together with historical
information and/or data to describe the biota expected in undisturbed or minimally disturbed
conditions. This combination of methods has been used to narratively describe level 1 in freshwater
BCG applications, and is well suited to BCG work in providing an anchored baseline. This approach
was used to predict the biological assemblages (fish and macroinvertebrates) expected in
undisturbed/minimally disturbed coral reefs in Puerto Rico (Section 6.5, pages 77-82). Expert
consensus is also valuable in adjusting best existing condition to more closely match naturally
occurring conditions. As a cautionary note, expert consensus may not succeed where data are sparse
and conceptual understanding of how the system responds to stress is poor (Thompson et al. 2012).

4. Components of the estuarine/coastal BCG
Combined approaches
Combinations of methods will also be effective. A BCG level 1 condition for fish assemblages has been
proposed for the Upper Mississippi River based on historical data combined with a statistical modeling
approach (U.S. EPA 2016 Appendix Bl). The Upper Mississippi (like many estuaries) is so altered that
undisturbed or minimally disturbed conditions no longer exist, yet conditions have more recently been
improving under better environmental management. To apply a BCG with a full range of condition,
a synthetic historical fish community was developed for level 1. Known ecology and habitat needs
of fishes that were abundant early in European colonization were combined with large data sets of
modern fish species occurrences linked to a gradient of chemical, physical, and biological stressors.
Statistically pairing the living requirements of historically abundant fish to this gradient of stressors
led to the synthetic historical fish community, which quantitatively anchored the undisturbed end of
the stressor gradient as BCG levels 1 and 2. The full gradient of condition was then used to derive BCG
thresholds for existing fish index measures, and these thresholds were used to assess ALU attainment
under the CWA. Further, the science-based quantitative descriptions of abundant historical fish
species (together with the fact that many of these species are still present) provides context and
motivation for restoration in the direction of BCG levels 1 and 2, even if these levels are unattainable.
This approach to historic data, while still in development, may be valuable for application to estuarine
and coastal aquatic ecosystems—the Upper Mississippi River system is similar to many estuaries in
complexity and extent of degradation. Other combinations of the four basic methods to determine
reference could also be helpful, and expert consensus contributes to all methods.
Regardless of methods used, development of level 1 (or combined level 1 and 2) undisturbed
conditions is a critical part of BCG in setting the anchor point from which other levels will be derived.
When BCG levels are distributed over the full range of condition, consistent level narratives allow valid
comparisons among measures and attributes at different sites or waterbodies, and at different times
from the past, present, and future. This is the foundation for many of the benefits of the BCG
Thresholds and decisions
Level thresholds: After specific attributes and measures have been selected, level 1 has been
described, and data from the full range of condition have been prepared for analysis, an expert panel
should be convened to develop narrative and then numeric decision rules for assigning sites to BCG
levels (U.S. EPA 2016) following attribute guidelines in Table 4-2, pages 30-31. This 'consensus of
experts' approach brings different scientific viewpoints together to assign local measures to BCG levels
in a well-documented and transparent manner. Expert consensus integrates divergent scientific
thinking and imperfect or limited data into numeric thresholds for determining impairments or
trajectories of condition. Clear and quantitative threshold values will best determine trajectories of
impairment and improvement. Managers gain clear and defensible scientific answers backed by
expert consensus, while scientists gain understanding and insight from discussions and consensus-
building, and see their work and perspectives incorporated into the management process.

Implementing the Biological Condition Gradient Framework
Documentation of process: The BCG focus on transparency and consistent communication of data,
methods, expert logic, and assessments has been extremely helpful to managers. Clear
documentation of the entire development process includes:
-	Defining how undisturbed conditions were identified, including the basis for assuming that these
conditions approximate "as naturally occurs"
-	Describing how and why biological measures, attributes, and attribute narratives were selected
-	Describing the decision rules and numeric thresholds for levels and how these were developed
by experts in workgroups or workshops
-	Identifying any limitations of the science or of the scientific tools that were used.
This transparency provides the rationale for decision-making, addresses any perception that
management decisions are random, and provides rigor for defense in any legal proceedings that
may follow.
Decision-making: The BCG provides mechanisms to help translate biology into useful information
for management decision-making. The BCG can be used together with societal values and economic
considerations to inform management decisions, as in the non-regulatory goals and targets developed
by NEPs. In regulation under the CWA, states and territories must establish designated uses for each
water body and describe the conditions that are acceptable for these uses, including scientific, social
and economic factors. Specific management applications are discussed in Section 5.2 (pages 42—44).
43. The Generalized Stress Axis (GSA)
Multiple stressors
Stressors, in the BCG construct, include any or all anthropogenic events, actions, and outcomes that
decrease biological integrity. These are addressed on the X axis of the BCG Gradient (Figure 2-2,
page 6) as the Generalized Stress Axis (GSA). The GSA is a conceptual description of the full range
(or gradient) of all anthropogenic stressors that affect the biology of the waterbody in question. This
full range can then be parsed into a set of specific controllable stressors with known stressor-response
relationships. The GSA can be quantified using proxies for cumulative human impacts in a watershed,
for example human population, land use/land cover metrics, or time in years from undisturbed or less
disturbed conditions (e.g., early in European colonization).
A GSA based on more detailed statistical analyses of land use/land cover data leads to a useful
understanding of how and where stressors are generated. Further, these data support identification
of specific controllable land-based stressors that contribute to cumulative impacts (U.S. EPA 2016).
This is valuable for linked watershed-estuary analyses, but since estuaries and coasts are also
impacted by oceanic and in-estuary processes, land use analysis alone may not be able to capture
all of the important stressors impacting coastal waters.

4. Components of the estuarine/coastai BCG
Natural stressors are not considered in the BCG as causing detrimental effects because they are a
part of the natural environments under which biota evolved. As is typical in estuaries, strong natural
abiotic gradients (e.g., salinity, flow, abiotic habitat) may be clearly related to the observed biological
gradient. Here, classification (Section 5.1, pages 39-42) can remove the influence of the natural
gradient by defining undisturbed conditions within each class. For example, an estuary may be
classified into mesohaline and polyhaline areas. Some natural stressors may be influenced or
exacerbated by anthropogenic actions. In these cases, the change to natural stressor levels is
characterized as the anthropogenic component of that stressor.
Stressors in the BCG are considered in aggregate as part of the GSA (U.S. EPA 2016) because
biological communities integrate the influence of multiple stressors (Figure 4-8). The GSA is helpful
in addressing cumulative impacts and as part of the decision rules used to calibrate the BCG. The GSA
also supports state CWA actions and is useful in goal-setting, communication, long-range planning,
and other applications in coastal management. The GSA can be evaluated using a variety of methods
and at any level of detail.
Figure 4-8. Small cove in Black Rock Harbor, CT, an estuary known for high levels of stressors including
toxicity, nutrients, sediment input, and habitat alteration. The GSA (BCG X-axis) represents the
synergistic aggregation of all these stressors; the BCG Y-axis evaluates their cumulative impacts on biology.

Implementing the Biological Condition Gradient Framework
Individual stressors
Many environmental efforts (such as the TMDL program) identify one or more stressors that should
be reduced. Restoration may also focus on a single stressor (e.g., nitrogen) to promote recovery of
resources such as seagrass. Specific stressors of concern should be identified when defining
waterbody problems, selecting attributes and measures, and characterizing biological response to
an overall stressor gradient. The GSA captures the cumulative effects of stressors and serves as
an organizing framework for individual controllable stressors. The Greenwich Bay historical BCG
(Shumchenia et al. 2015) examined overall change in biological response over time, but also identified
the specific stressors impacting the embayment. Identifying the specific causal stressor or stressors
can also allow use of the diagnostic decision process (U.S. EPA 2010 [http://www.epa.gov/caddis],
Ho et al. 2012) that allows further management and improvement of the waterbody.
More sophisticated use of the stressor gradient has taken place in streams when large data sets
are available. Kashuba et al. (2012) used a Bayesian network model to identify the probability of
achieving a desired BCG level given a defined management action. For example, if management
actions reduced flashiness and specific conductance to certain levels in an urban stream, the
probability of receiving a BCG level 3 or better designation would increase from 24% to 70%.
Thus, BCG stressor work adds greater scientific understanding of the impacts to biological
communities while providing critical information and targets for TMDL work, other load reduction
efforts, and restoration. Stressor-response models linked to BCG levels are necessary for
management of specific stressors in the BCG framework. The GSA serves as a conceptual basket
that holds individual stressor-response models and captures their cumulative effects in a quantifiable
way. See U.S. EPA (2016) Chapter 5 and Appendix A for more information and detailed examples.

5. Application of the approach
5. Application of the approach: details and examples
5.1. Classification
Why classify?
Developing a basic understanding of the waterbody (or waterbodies) in question is fundamental
to coastal and estuarine management. Coastal systems across the U.S. occur in different sizes and
shapes, with varying bathymetry, tidal influence, volume of river inflow, circulation patterns, etc.
Within any given system, high spatial and temporal variability support multiple habitats and biological
communities. This complexity has led scientists and managers to treat each coastal and estuarine
system as a unique entity (Kelly 2008). Yet, these diverse and complex systems can be described
and classified through basic sets of geomorphologic, hydrologic, and physical characteristics
(Engle et al. 2007). Classification allows coherent groups to be identified so as to inform or simplify
a management question (Kurtz et al. 2006). Classification further allows information from one
estuary or coastal area to be applied to another, minimizing the need for intensive individual studies
of similar coastal systems (Figure 5-1).
Figure 5-1. Two adjacent lagoonat estuaries (Green Pond and Great Pond, Cape Cod, MA).

Implementing the Biological Condition Gradient Framework
Classification of estuaries
Many classification schemes have been developed for dividing estuaries into similar groups.
Geomorphic classifications (e.g., Pritchard 1967, Dyer 1973) use geologic origin or geology to define
estuary classes. Estuaries can be classified as drowned river valleys, fjords, deltas, lagoons, and
tectonic estuaries. Hydrodynamic classifications (e.g., Strommel & Farmer 1952, Hansen & Rattray
1966) use circulation and stratification to define estuary classes. Briggs (1974) developed a
classification based on zoogeographic regions used by the U.S. EPA's National Coastal Condition
Assessment (NCCA). On a smaller within-waterbody scale, habitat classification allows descriptions
and inventories of habitats and communities. Classifying data by sediment type, habitat, latitude,
salinity, or other influencing factors reduces variability in analysis and is valuable for evaluating
changes over time or space. One of the best known habitat classifications is the Cowardin et al.
(1979) scheme, which is hierarchical, starting with system (e.g., marine, lacustrine), and then using
physical and habitat features along with modifiers to classify habitat type. This model has been
further developed into the federally approved Coastal and Marine Ecological Classification Standard
or CMECS (FGDC 2012), which has been adopted and is used by many state agencies, several federal
agencies, and a number of academic and management groups. This standard assists in classifications
of habitats, estuaries, and coastal areas of all types (Figures 5-1, 5-2, and 5-3).
Figure 5-2. An anthropogenic estuary built behind breakwaters (San Pedro Bay and Long Beach,
Los Angeles, CA). Image: Google Earth, data from Landsat

5. Application of the approach
Figure 5-3. Entrance to a small riverine estuary (Narrow River, Rl).
Classification to meet different needs
More recently, estuarine classification systems have been developed for specific purposes. Edgar
et al. (2000) developed a system to identify conservation status. Estuaries were assigned to groups
based on geomorphology and hydrology. Fish and benthic invertebrate community structures were
used to validate and refine these estuary groupings, which were then ranked based on catchment
stressors (e.g., population, land use). Biological data were examined for biodiversity and endangered
species, allowing the individual estuaries to be categorized into one of six conservation levels. Bricker
et al. (1999) classified estuaries by their susceptibility to nutrient over-enrichment using physical
measures of dilution and flushing. In a study in Chesapeake Bay, Boynton and Kemp (2000) suggested
that classification may allow normalization of important factors so as to develop stressor-response
relationships that could be applied in multiple estuaries.
Classification can be used for many purposes, including "describing and inventorying communities
and habitat types, examining differences and similarities between groups, identifying and prioritizing
conservation efforts, managing resources, and guiding research" (Engle et al. 2007). The type of
classification chosen in a project will be determined by the questions being asked. If the priority
is to describe and inventory habitats and communities within an estuary, then geomorphic,
hydrodynamic, or habitat classification may be most appropriate. Assessment within groups
of similar biological expectation determined by (for example) salinity, depth, or substrate type
can improve the quality of assessments by eliminating data from different environmental regimes.
Managing resources, especially for TMDL or nutrient reduction work, may require identification of
susceptibility (Bricker et al. 1999) and/or normalization (Boynton and Kemp 2000) so that appropriate

Implementing the Biological Condition Gradient Framework
load-response relationships can be developed. If the differences and similarities between coastal
estuaries need to be examined or if conservation efforts need to be prioritized, then further
examination of conservation status groups as in Edgar et al. (2000) could be helpful.
For BCG application, the European Water Framework Directive (WFD) may be particularly relevant.
Here, estuaries and coastal waters are defined into types or classes based on physical and chemical
factors that determine the structure and function of biological communities. Waters are assigned
using (primarily) biology into one of five status (condition) categories (equivalent to BCG levels)
using a reference condition that is based on high status in other waters as the preferred method
(EC 2002). Reference conditions are determined within the same type or class of estuary (U.S. EPA
2011b) so that expectations are appropriate to the physical constraints of the system. For example,
reference conditions from an open embayment would not be applied to a lagoon. The extensive
work applying the WFD to European estuaries and coasts provides methods and lessons helpful to
the application of BCG to U.S. estuaries and coasts. See also the "Six required steps for managing
European estuaries" text box on page 83.
Grouping or classification allows better transfer of data, models, and lessons learned from one
estuarine or coastal system to another. Although our estuaries and coastal systems are unique
resources valued in different ways by their residents and stakeholders, classification creates
management opportunities to better protect a specific or unique system through comparisons
to other similar systems. Classification within an estuary streamlines and focuses biological
assessments. Classification of nature is a well-developed scientific field that can provide benefits
to all forms of environmental management.
5.2. How can the BCG improve management of estuaries and coastal waterbodies?
This BCG guidance provides a flexible approach that can be adapted to fit the unique characteristics
and management needs of an individual estuarine or coastal waterbody (or a classified set of
waterbodies) and then developed to make best use of the resources and data that are available.
The ability to make valid comparisons across measures, space, and time provides many benefits.
The estuarine and coastal BCG was designed to provide national, regional, state, and local managers
with scientific information needed to improve the environmental condition of their waterbodies.
Who can benefit?
National managers (e.g., the U.S. EPA Ocean and Coastal Protection Division) benefit from consistent
assessments of estuaries and estuarine biology. This improves communication and allows more
comparable national reports on the condition of estuaries and estuarine resources. State managers
benefit from the ability of the BCG to help with CWA goals: refine designated uses, develop
biocriteria, identify high-quality waters and watersheds, and document biological response to
stressors (U.S. EPA 2011a). Consistent assessments guide development of thresholds for Aquatic Life
Uses, TMDLs, the management of single or multiple stressors, and the communication of condition
to define goals and monitor progress. The BCG provides rigorous and transparent results that can be
used in regulation. This has been demonstrated in streams, and the concepts are equally applicable

5. Application of the approach
to management of estuaries. Applications of the BCG to state management and regulatory goals
are discussed in U.S. EPA (2016).
Local and regional non-regulatory management groups including NEPs, NGOs, Regional Planning
Bodies (RPBs), municipal planners, and others are assisted in communicating with stakeholders,
determining agreed-upon vision statements for desired future conditions, setting goals and targets,
prioritizing actions, and tracking progress towards targets and goals. The estuarine/coastal BCG
approach (or any part of it) can also be applied within a larger management program, for example
EPA's Healthy Watersheds Initiative, which embraces many of the same principles. Managers will
also find other advantages in using the BCG.
The estuarine and coastal BCG implementation approach considers waterbodies at several scales,
and extends several uses of the stream BCG approach to the management of larger systems:
1.	Assessing (consistently interpreting the environmental conditions that exist). The BCG defines
undisturbed conditions, then BCG levels consistently evaluate existing conditions relative to
those undisturbed conditions using data from any relevant biological measure at scales ranging
from organisms to waterbodies. Consistent assessments are the basis for effective management
from goal setting to monitoring to CWA decisions.
2.	Developing visions, goals, and targets (providing information to support consensus on desired
environmental conditions). Comparing existing conditions of valued biological resources to
higher quality (more natural) conditions expected with stressor reductions can help develop a
stakeholder vision of what is desirable and attainable for the future. Levels of condition linked
to specific attributes and measures can lead to both narrative and quantitative targets towards
visions and goals. Ultimately, a compelling vision of a desired future can engage stakeholders
to take action and generate the political will to protect and improve their waterbody; for added
motivation this vision can also be compared to the 'do nothing different' future (see number 5
3.	Informing specific management actions (identifying and prioritizing the stressors most relevant
to achievement of goals). Additional development of the GSA and stressor identification (see
www3.epa.gov/caddis) can help parse out the stressors (including stressors in the watershed)
that most contribute to cumulative impacts. This may also provide information to: identify the
specific and generalized stressor values that determine biological condition levels; develop actions
to manage those stressors; and evaluate whether environmental targets and goals are realistic.
4.	Monitoring progress (providing measures and levels to track progress towards desired
conditions). The same measures, attributes, and levels that were used to set targets for an
individual waterbody are then used to track progress towards those targets. Direct methods
to evaluate improvement or degradation lead to more effective adaptive management.

Implementing the Biological Condition Gradient Framework
5.	Predicting future scenarios (projecting current or alternative trajectories into the future). In many
cases the consequences of a 'do nothing different' management option can be predicted with
historic BCGs by extending the existing condition trajectory into the future (Cicchetti and Greening
2011). This may help management groups and communities prevent or prepare for undesirable
future conditions.
6.	Communicating (translating ecology into terms that are more easily understood and
communicated). BCG levels are easily understood as six grades of condition for what we have,
what we have lost, and what we can restore, relative to the natural state. The concept of restoring
valued resources that once existed can resonate with the public and stakeholders (Cicchetti and
Greening 2011). Further, BCG addresses issues specific to an estuary and includes resources that
are valued by local stakeholders. BCG levels can easily be converted into another form that may
appeal to certain groups (report cards, bar graphs, color codes, etc.). The BCG is a basis for
communication with many different audiences.
A goal of an estuarine and coastal BCG is to consider the estuary or coastal area and its stressors
in a comprehensive manner by combining consistent assessments at multiple scales. The BCG can
serve as a conceptual 'box' that is capable of capturing a wide range of scales and sub-regions from
watershed headwaters to the near coastal edge. This provides an ecological foundation for
integrating environmental and socioeconomic management.
All of the above benefits, however, presume that scientists and managers are well-informed as to
the underlying science of how their estuary functions, the human stressors that most alter that
function, the environmental, social and economic priorities of the local communities, and the
resulting management problems that need to be addressed (i.e., estuarine BCG implementation
Step 1). It will be difficult to develop a useful BCG model unless it is clear what needs to be assessed
and why. On the other hand, certain aspects of BCG development can assist with this process; for
example, an understanding of the historical distributions of biological resources may help clarify
goals and objectives.
In situations where objectives are uncertain, initial actions can be taken to apply larger socio-
ecological management approaches that better define environmental, social, and economic needs;
incorporate stakeholder values; clarify desired objectives; identify stressors; and balance opposing
goals. This allows BCG assessments to address those issues most relevant to stakeholders and
managers. In some cases, values articulated by stakeholders (e.g., protect charismatic megafauna,
figures 5-4 and 5-5) can be addressed through more tractable BCG measures (e.g., habitat quantity
and quality). Larger social frameworks used together with BCG can address these and other issues.

5. Application of the approach
Figure 5-4. Large charismatic animals appeal to public sentiment, and are often dependent on high
water quality and suitable habitat availability. Manatee calf resting chin on mother's back, Weeki
Wachee River, FL. Manatees require abundant aquatic vegetation for food and access to clean fresh water
for osmoregulation. Photo: N. Cicchetti
These larger approaches include Structured Decision Making (SDM) (Gregory et al. 2012), Ecosystem-
Based Management (EBM) (McLeod and Leslie 2009), Drivers-Pressures-State-Impacts-Responses
(DPSIR) (OECD 1994), and Coastal and Marine Spatial Planning (CMSP) (White House Council for
Environmental Quality 2010). BCG levels can also be linked to ecosystem service values. Of these,
SDM, DPSIR, and EBM have been used directly with BCG (Carriger et al. 2013, Corbett 2013, Yee et al.
2014, Shumchenia et al. 2015). These larger methods are valuable in any decision-making process,
and a better understanding of the ecological-social-economic landscape can benefit any BCG effort,
even after objectives and assessment goals have been established.
Structured Decision Making
Structured Decision Making is an approach that applies human benefits and stakeholder values
to identify clear objectives and evaluate management alternatives. The basic organization of SDM
(USFWS 2008, Gregory et al. 2012, Carriger et al. 2013, Yee et al. 2014, Bradley et al. 2015)
is as follows:
1.	Clarify the decision context - identify the significant problem(s) to be solved, and the
stakeholders involved.
2.	Define objectives and performance measures-develop environmental, social, and economic
objectives (usually in the form of 'more X, and less Y') that reflect stakeholder values. An
objectives hierarchy is used to organize this from broad values or 'fundamental objectives',

Implementing the Biological Condition Gradient Framework
to specific objectives ('means objectives'), to actions, to performance measures that track
progress towards the objectives.
3.	Develop alternatives - propose different management approaches, methods, or thresholds
through which objectives may be achieved, involving stakeholders in the process.
4.	Evaluate alternatives and select management actions; predict likely outcomes and
consequences of alternative approaches, in general applying scientific methods. Evaluate
tradeoffs with stakeholder input. Select the best approaches and actions as a management
decision that is informed by science and stakeholders.
5.	Implement, monitor, and review - initiate actions, monitor results using quantitative measures,
and review to support adaptive management.
In Puerto Rico (Section 6.5, pages 77-82), SDM was used prior to development of a coral reef BCG
to identify the fundamental objectives of managers and stakeholders, along with potential measures
in an objectives hierarchy (Carriger et al. 2013, Bradley et al. 2015). This objectives hierarchy
provided a clear list of desired goals and performance measures. For example, a fundamental
objective was 'maximize ecological integrity'. A sub-objective was 'living habitat condition (seagrass,
mangroves, corals).' Performance measures were 'living habitat condition indices'. Once objectives
had been defined, a means-ends network was used to develop those objectives (ends) and link them
to proposed actions (means) from a watershed management plan (Carriger et al. 2013). SDM
provides a clear understanding of linkages between objectives and management actions, engages
stakeholders, helps identify gaps, and facilitates evaluation of alternatives.
As part of SDM in Puerto Rico, the DPSIR framework provided further management context for BCG
development (Bradley et al. 2015, 2016). DPSIR is a comprehensive human-focused decision-making
framework that integrates humans, management, socioeconomics, and ecology. The DPSIR terms
have been defined in slightly different ways, especially with regard to 'Pressures', but in a general
form DPSIR includes five stages. 'Drivers' are basic human needs and their influences (e.g., need for
sustenance, living space, removal of waste), and 'Pressures' are the human activities and stresses
that Drivers place on the environment (additions of nutrients and toxins, destruction of natural
habitat). 'State' then describes the resulting environmental conditions (macroalgal biomass,
dissolved oxygen levels, seagrass acres, and benthic faunal indices). 'Impacts' describe the
resulting losses or changes to ecosystem services (valuable resource losses, fish kills, unsustainable
environments, loss of enjoyment of nature). 'Responses' are the actions taken by management
to address Impacts and changes in State (regulation of Pressures, restoration of State). DASEES
(www.dasees.org), described along with other SDM tools in Bradley et al. (2015, 2016), is an
online user-friendly platform to help practitioners use both SDM and DPSIR. For projects exploring
environmental links to human health, EPA has expanded the basic ecological version of DPSIR to
include human health/social issues on a parallel track. This Eco-Health DPSIR model better integrates
the relationships between humans and the environment, and is thoroughly discussed in Bradley and
Yee (2015).

5. Application of the approach
The BCG stressor-response approach is embedded in the D-P-S-l portion of the ecological DPSIR
framework. Anthropogenic BCG stressors can be DPSIR Drivers (e.g., need for living space and
urbanization), Pressures (e.g., nutrient additions, filling of wetlands, increased siltation) or States
(e.g., low dissolved oxygen levels, sediment toxicity). Biological BCG responses can be DPSIR States
(diversity measurements, benthic condition indices, seagrass abundance) or Impacts (decreased
biodiversity, loss of societally valued seagrass), noting that in the BCG approach, 'response' is used
in a stressor-response construct, and has a different meaning than does 'Response' in DPSIR, where
the term is used to describe management actions. In Puerto Rico, DPSIR was used to organize
scientific knowledge, stakeholder values, and conceptual linkages in a transparent way, and to help
establish the decision context with which to identify fundamental objectives (Yee et al. 2014,
Bradley et al. 2015). Within SDM and DPSIR, the coral reef BCG was valued for its ability to provide
the Pressure to State linkages and identify indicators. BCG allows a consistent determination of reef
condition that informs management actions across many reefs and reef areas, and plays an important
role within both SDM and DPSIR.
In the Greenwich Bay (Rl) BCG (see this document Section 6.1 [pages 61-65] and Shumchenia et al.
2015) the DPSIR framework was used to build a conceptual model of the complex pathways among
Drivers (human needs), the resulting Pressures (which were BCG stressors), State (which captured the
cumulative effects of stressors), and Impacts (which were linked to the biological response indicators
used in the BCG). These response indicators were eelgrass loss and replacement, benthic community
changes, and primary production/shellfish-which are connected in Greenwich Bay. This combination
of indicators addressed shallow substrates, deeper substrates, the water column, and valued species,
representing major components of estuarine biology. The DPSIR model organized the ecosystem,
included humans, identified BCG stressors, and linked them to meaningful indicators of biological
condition. Combining DPSIR and BCG better clarified the workings of the human-ecological system
(Shumchenia et al. 2015).
As a complementary management approach, managers, scientists, and stakeholders can work to
develop a consensus-based vision of a desired future state for the waterbody of concern. This is an
effective tool for initiating and guiding environmental efforts. The concept of building desired future
conditions into management is critical to both SDM and EBM (Carriger et al. 2013). National Ocean
Council guidance for regional marine planning (National Ocean Council 2013) also includes a visioning
step. Visioning is aligned with the BCG approach, and can take place before, during, and after BCG
development. An early or pre-BCG vision can inform selection of the biological condition measures
that are most relevant to the desired future state. A developed BCG can be used to derive or refine
a stakeholder vision by describing changes to estuarine condition over time. What was our estuary
like in the past (levels 1 and 2)? What is our estuary like now? What do we want our estuary to be
like in the future? This last leads to the vision, in the context of what we had, what we have, and
what we want. If no new actions are taken, forward projections of current environmental trajectories
can suggest possible future conditions-perhaps levels 5 or even 6.

Implementingthe Biological Condition Gradient Framework
A BCG visioning approach can be applied to a specific sub-area or to the overall condition of a coastal
waterbody or estuary. Public and stakeholder outreach and workshops can lead to an agreed-upon
vision for a desired estuarine condition that resonates with and motivates the public. Objectives,
BCG attributes, measures, BCG level targets and actions can be chosen to address the vision.
Environmental effects of these actions and progress towards targets, objectives, and the vision
can then be monitored and reported using the same measures and consistent BCG levels.
The Tampa Bay Estuary Program (Section 6.2, pages 66-70) used these concepts very effectively,
developing a simple and unifying vision to protect and restore certain valued biological attributes
to conditions experienced in the 1950s. This vision of a desired future motivated the public and led
to specific goals and targets that drove management actions (Cicchetti and Greening 2011). In 2015,
the Tampa Bay Estuary Program achieved (and then exceeded) their original goal of restoring
seagrass to the historic acreage present in 1950 (TBEP 2015). The vision of moving Tampa Bay
ecosystems back towards earlier conditions and to 'restore the balance' of Tampa Bay habitats led
to an engaged public, which was a critical element in the success of the program.
Figure 5-5. Charismatic brown pelican in Tampa Bay, FL, Photo: NOAA
Larger decision-making approaches like SDM and DPSIR, visioning, and BCG are valuable tools that
can benefit states, NEPs, NGOs and similar organizations in their roles as conveners of different
management and stakeholder interests. This work aligns with principles of integrated management
(e.g., EBM): evaluating and managing the waterbody and watershed to achieve ecological, societal,
and economic goals through involvement of many different groups and partners. This broad
participation is an effective way to address the continuing degradations caused by cumulative
impacts of multiple stressors.

5. Application of the approach
5.4. Overall estuary or waterbody condition
Why evaluate overall condition?
The public arid stakeholders are often very concerned about the overall condition or health of their
particular waterbody, whether that is a cove or bay where they live, swim, or fish, or an entire
estuary or coastal area. This concern is best addressed with an assessment of the overall condition
of that system and the multiple stressors that affect it. The BCG makes the appealing concept of
waterbody 'health' meaningful through consistent comparisons to past conditions, and to conditions
in other locations. Moreover, evaluating overall condition helps prioritize stressors to best address
waterbody-level problems.
Figure 5-6. West Falmouth Harbor, MA, a small lagoonal estuary located down-flow from a groundwater
injection sewage treatment facility. Note abundant sea grass in 2002. A good candidate for BCG
monitoring of overall condition over time.
How to evaluate overall condition
Overall condition of an estuary (or other waterbody) is difficult to measure. First, overall condition
or state derives from the conditions of the major subcomponents, their connections, and their
combined functions. Consequently, the waterbody should be considered as a system to include these
interactions. Classifying the waterbody (Section 5.1, pages 39-42), then assembling a conceptual
ecosystem model or diagram of the physical, chemical, and biological processes that structure the
system helps understand overall condition. Estuaries are spatially and temporally variable, with

Implementing the Biological Condition Gradient Framework
notable differences in structure and function along the axis between head and mouth, and along
transects from intertidal to deep waters.
Several methods and proxies have been developed to evaluate overall condition of the estuary or
coast, all of which could be included in a coastal and estuarine BCG through comparisons to
undisturbed or minimally disturbed conditions. Ideally, the set of biological measures chosen would
cover as much of the entire estuarine gradient as possible, and incorporate several components of
the estuary (e.g., intertidal and subtidal; primary and secondary production; benthos and nekton).
In practice, this will be limited by data availability. Different approaches (which can be combined)
to assess overall biological condition are described below.
5.4.1. Structural measures (e.g., number and type of organisms, acreage of habitats). The structure
attribute is often used in BCG for practical measurements and repeatable assessments of biological
5.4.1.a. Assessment with a single structural measure of condition: in some cases, one well-chosen
measure may meet management requirements for evaluating overall condition.
Keystone species, which have large and disproportionate effects on the ecosystem relative to their
abundance (Power et al. 1996), may be monitored to assess overall ecosystem condition. An example
is the U.S. west coast sea otter. In the absence of otters, sea urchins can completely graze down a
kelp forest, leaving a barren seafloor. The otter feeds on the urchins, keeping their population in
check, and maintaining the kelp forest (Estes and Palmisano 1974). However, recent work suggests
that the influence of keystone species may be context specific (Power et al. 1996), density-
dependent, or show lags in response (Dean et al. 2000, Konar 2000). Keystone species should be
used cautiously as a sole measure of overall condition.
Individual species or assemblages may also be assessed as indicators of overall condition when they
respond predictably to environmental stressors over a range of impact. Seagrass, for example, is
very sensitive to water quality (Dennison et al. 1993) and has been used as an indicator in many
estuaries. In general, plentiful beds of healthy seagrass in shallow areas of an estuary indicate
good overall condition, and the beds further provide important habitat for valued fauna
(Figure 5-7). Benthic invertebrates have also been used to assess the overall health of coasts and
estuaries. EPA has consistently collected benthic invertebrate data in estuaries since 1990 (U.S. EPA
2001, 2004, 2008, 2012) and summarizes estuarine condition using area-weighted benthic index
values (U.S. EPA 2006a). SCCWRP uses benthic invertebrate data and locally developed indices
to assess coastal health in southern California (http://www.sccwrp.org/ResearchAreas/
RegionalMonitoring). Other common indicator assemblages include wetlands, shellfish reefs,
and fishes.

5. Application of the approach
Figure 5-7. Seagrass habitat is important for the settling and development of juvenile conch.
The waterbody is good if several critical parts of it are good
5.4.1.b. Assessment with multiple structural indicators of condition: several species, communities,
or habitats may be used together for a more robust overall evaluation that is less prone to annual
or seasonal variability.
This approach has been used to evaluate and communicate condition in many estuaries and water-
bodies. The Massachusetts Estuaries Project (http://www.oceanscience.net/estuaries/about.htm)
uses both seagrass and infaunal invertebrates as indicator species. The Chesapeake Biotic Index
(http://ian.umces.edu/ecocheck/report-cards/chesapeake-bay/2011/indicators/biotic_index) jointly
assesses seagrass, benthic invertebrate communities, and phytoplankton communities to provide
an overall measure of condition for the entire Chesapeake Bay or for specific spatial areas of the
Bay. The health of the living resources of Buzzards Bay is determined by assessing present
condition of eelgrass, bay scallops and river herring in comparison to historic (pre-1900) condition
(http://www.savebuzzardsbay.org). Similarly, the Greenwich Bay (Rl) BCG (Section 6.1, pages 64-65)
evaluated seagrass, benthos, and a combined primary production/shellfish measure. Assessment
with multiple indicators depends on the availability of data for each indicator and may not be
practical in poorly studied waterbodies.
The waterbody is good if its mix of habitats is good
5.4.I.C. Assessment of the extent, composition, or arrangement of living habitats (biotopes): the mix
of critical living habitats within a waterbody reflects waterbody-scale changes due to anthropogenic
stressors and these habitat mixtures can be evaluated with statistical tools.

Implementing the Biological Condition Gradient Framework
Biotopes are repeating combinations of physical features and biological communities, named after
the dominant biota (see Appendix B, Question 9). Productive estuaries in a natural state are a mosaic
of biotopes (Henningsen 2005), including seagrass beds, oyster reefs, mussel reefs, salt marshes,
mangrove forests, clam flats, and specific soft-bottom benthic communities. The biotope mosaic
approach is a relatively new structural metric that evaluates the condition of a waterbody through
the mix of biotopes it contains (Figure 5-8), just as the condition of a faunal community is evaluated
through the mix of species it contains. This method considers biotopes as critical elements of
estuarine biology, and quantifies extent (acreages), composition (proportions), or arrangement
(spatial distributions) of the important biotopes within an estuary relative to minimally disturbed
conditions from a previous or historic state.
Anthropogenic stress to an estuary leads to destruction and alteration of natural biotopes through
removal (e.g., filling a wetland) or replacement with other biotopes (e.g., soft sediment fauna
replaces a seagrass biotope). A basic tenet of the approach is that restoration towards the mosaic
that would naturally occur will provide the greatest benefit for the native communities of organisms
that have evolved in that setting over millennia, thereby improving biological integrity. Use of
the biotope concept in management is described in Cicchetti and Greening (2011), and biotopes
are incorporated into classifications of biology in CMECS, a federal standard (FGDC 2012).
Figure 5-8. Aerial views of heads of two sub-estuaries showing biotopes. Left: a sub-estuary on Martha's
Vineyard (MA) showing seagrass, salt marsh, and maritime forest. Right: a sub-estuary in Long Island
Sound (CT) with no natural biotopes identifiable in the shallow subtidal, intertidal, or adjacent uplands.
Historical and present-day habitat distribution data are often available for estuaries through early
and recent maps, charts, photos, or habitat acreage studies. GIS methods are extremely helpful, and
this waterbody-scale evaluation can be very useful in showing major degradations and improvements

5. Application of the approach
over long time periods in a BCG. Biotope measures (e.g., extent, relative proportions, diversity, and
fragmentation) are inherently quantitative, and loss of certain habitats may identify specific stressors
of concern, e.g., loss of seagrass may identify poor water clarity as a stressor while loss of salt marsh
may identify filling or sea level rise as stressors.
Perhaps most importantly, the method tells a compelling and intuitive story for public and
stakeholder communication. This is described for the Tampa Bay example in Section 6.2 (pages
66-70). While the term 'biotope mosaic' provides a clear link to biological integrity and the BCG,
the synonymous term 'habitat mosaic' (or any other language) may be used for more immediate
understanding by public audiences.
Structure and function
Many of these structural measures (Sections 5.4.1.a, b, and c above) are assumed to be surrogates
for function and condition. Because species (Sections 5.4.1.a and b) occupy specific niches, they
have specific functional roles. For example, benthic invertebrates are involved in nutrient cycling,
oxygenation of sediments, and building seafloor structures. Structural measures such as species
abundance and diversity are often evaluated, but feeding type or pollution sensitivity metrics based
on species abundance can also been used to assess condition. An expansion of this approach is
biological traits analysis, which uses the life history characteristics of individual species to assess
ecosystem function (Bremner et al. 2006). Biodiversity is also related to ecosystem function
(Naeem et al. 1999). Here, a decrease in ecosystem function is likely related to the species that
become locally extinct (Cardinale et al. 2006), the functional characteristics of those species, and
the types of ecosystem and functional pathways within the system (Hooper et al. 2005). A similar
structure and function assumption can be made about biotopes (Section 5.4.l.c) in the larger
estuary. Since each biotope provides a unique set of species and functional contributions, the
overall function of the estuary is expected to change when the extent and relative proportions of the
individual biotopes change.
The waterbody is good if it works as it should
5.4.2. Measures of ecosystem function and connectance. Biological measures that quantify
processes of ecosystem function include evaluations of energy flows, trophic webs and linkages,
carbon or nutrient fluxes, production of diverse biomass, nutrient processing, rates, or resilience
to changes. Measures that capture complex interactions in the entire estuary may be particularly
valuable. These larger processes are often assessed using proxies that are easier to evaluate,
including structural measures as mentioned above.
Measurements and proxies of functional processes include photosynthesis:respiration ratios;
benthic-pelagic exchange and production rates; benthic bioturbation and nutrient cycling;
chlorophyll o concentrations; macroalgal biomass; biodiversity; other comprehensive measures of
biological organization; exchange, export, sedimentation, or migration rates; or results from flux
chamber work and trophic analyses. Bioturbation is a proxy for benthic ecosystem function (Solan et
al. 2004, Teal et al. 2010) and is relatively easy to assess as the depth of the color discontinuity in the

Implementingthe Biological Condition Gradient Framework
upper layers of sediment. Similarly, chlorophyll a may serve as a proxy for ecosystem function and
is also relatively easy to assess, particularly given new methods of remote sensing. Together, these
proxies can cover the vertical profile of an estuary from surface to bottom.
Connectance can refer to the connections of populations among patches, the relationships between
habitat patches and the organisms that move between them, or the extent to which the system
allows movement of organisms (Kindlmann and Burel 2008). As with ecosystem function, this
attribute is more easily measured using proxies, such as landscape ecology metrics from a biotope
mosaic approach (when estuarine data allow spatial GIS analyses). These proxies include nearest-
neighbor analyses, evaluations of corridors or fragmentation, and other approaches to measure
spatial dispersion and arrangement of habitats. Other proxies for connectance may include analyses
of metapopulation stability, anadromousfish runs (Figure 5-9), or hydrodynamic and current data
(Figure 4-4, page 27) which can be used to help predict isolation or dispersal capacity. As in all cases,
the logic behind selection of proxies should be clearly explained.
Figure 5-9. Migrating coho salmon show connectance between oceans, estuaries, and streams.
Photo: NOAA
The waterbody is good if biology is good and stressors are low
5.4.3. Combining biological condition and stressors. This is an often used and effective assessment
and communication tool that supports the use of stressor-response models in management. Any of
the above measures of biology can be combined with a stressor evaluation. The GSA (Section 4.3,
pages 36-38) links directly to BCG levels in evaluating the sum of the cumulative stressors to which
biota is exposed. The GSA can be characterized with proxies for anthropogenic stress including

5. Application of the approach
human population numbers, ambient pollutant levels, combinations of primary individual stressor
levels, or time. Analyses of changes in watershed land use overtime (e.g., changes in percent of
impervious surface or use of a landscape development index) relate to BCG levels and provide
information on the nature and distribution of cumulative stressors and their sources (U.S. EPA 2016).
These spatial analyses are useful for communicating stressor information and for managing at the
watershed level. Further, the GSA can be parsed into the individual stressors that contribute to
cumulative impacts and can help to prioritize these stressors.
In one example of this approach, overall health of Chesapeake Bay is calculated by combining the
biotic index mentioned above (Section 5.4.l.b, page 51) with a water quality stressor index that
includes water clarity, chlorophyll a, and dissolved oxygen measures. Overall health can be
calculated bay-wide or for individual sections of the bay. Similarly, overall status of Buzzards Bay
is determined by combining living resource indicators with indicators of pollution (nitrogen, bacteria,
and toxics) and watershed health (forest, streams, and wetlands). In developing the Puerto Rico coral
reef BCG, investigators combined measures of the reef and associated biological communities with
water clarity to define different levels of condition.
In a BCG for Greenwich Bay Rl (Figure 5-10), information from three biological indicators and several
attributes was put together with information on a GSA and on specific stressors. This produced an
integrated estuary-wide Biological Condition Gradient with an analysis of stressors and their
cumulative effects over historical time (Section 6.1, pages 63-65). The approach is valuable in
describing the current state of the estuary together with the significant events and processes that
have shaped it overtime. This provides context and information for scientists and managers working
on any question or issue within the estuary, helps prioritize the stressors most important to the
waterbody, and reinforces public and management perceptions of a thorough and meaningful
research effort.
Figure 5-10. Northeast corner of Greenwich Bay, Rl.

Implementing the Biological Condition Gradient Framework
More on overall condition
The EU approach (see text box on page 83) uses the overall condition of waterbodies as the primary
basis for regulatory decisions. In brief, a set of rules is used to develop status (condition) levels for
each of four biological elements: phytoplankton, flora, benthos and fish. Overall waterbody status is
determined as the lowest status among the four elements, and regulatory requirements start in with
a status below 'Good' for any one element, secondarily considering hydrogeomorphological elements
(e.g. dams, dredging) and physico-chemical elements (e.g. toxicants, nutrients). DPSIR is used to
evaluate alternative management methods to restore 'Good' status. This somewhat prescriptive
approach is used to ensure that Member States are effectively and consistently regulating their
Generally speaking, the public and stakeholders care about the overall condition of their
estuary. This is a scale at which people think about waterbodies, and think about waterbody
improvement. This scale is also effective for evaluating and managing the biological effects of
cumulative impacts, because these effects manifest throughout the entire estuary. For practical
application, developing a BCG for the overall condition of an estuary together with a stakeholder
vision for a desired overall future estuarine condition is an effective approach to management,
and may be of particular benefit to NEPs. Although estuarine and coastal ecosystems are used to
illustrate this, these methods can apply to overall assessment of any defined ecosystem. A BCG
may be developed to assess and manage areas of high ecological importance within a larger setting,
including large rivers, oyster reefs, or rocky outcrops in otherwise soft-sediment areas. Here, the
estuarine and coastal BCG may assess overall condition of the ecosystem or area of interest using
any of the methods described above, or other more specific approaches.
5.5. Sustainability and the estuarine/coasta! BCG
Sustainability has been adopted by the U.S. EPA as a major goal for research, management, and long-
range planning. The Agency defines sustainability as "meeting the needs of the current generation
while preserving the ability of future generations to meet their own needs" and recognizes the three
pillars of sustainability as "economy, environment, and society" (Anastas 2012, see Figures 5-11, 5-12,
and 5-13). In the estuarine and coastal BCG, environmental sustainability evaluates the ability of a
functioning ecosystem to maintain those functions given past, existing, and future levels of stress
and disturbance. The BCG can address the societal pillar of sustainability through stakeholder
involvement and stakeholder-driven visions of a desired future estuary-thus exploring the needs
of future generations (Section 5.3, pages 47-48). Information on economic sustainability can be
provided though an ecosystem services analysis linked to BCG levels. However, the BCG is
strongest in characterizing environmental sustainability; other tools can better evaluate
economic and societal sustainability.

5. Application of the approach
Figure 5-11. Economy: investment in recreational fishing. Columbia River, OR and WA, Photo: NOAA
Figure 5-12. Environment: seagrass and staghorn coral, both sensitive species, in the Florida Keys
Marine Sanctuary. Photo: NOAA

Implementingthe Biological Condition Gradient Framework
Figure 5-13. Society: public enjoyment of the seashore. Town Beach, Charlestown, RI.
The historical investigations that often accompany an estuarine BCG are useful in evaluating
sustainability in coastal systems, because trends over time show trajectories that may or may not
lead to support of future needs. Historical evaluations of Tampa Bay habitat mosaics showed that
the estuary continuously degraded from 1900 through 2005, and so the environment and associated
ecosystem services were not sustained-and would not be sustainable into the future given that
trend. In recent years, after concerted public and private efforts that began in the 1970s, trends
were reversed, sustainability of valued habitats has improved by way of meeting the needs of
future generations, and habitat measures have been trending up (Cicchetti and Greening 2011,
TBEP 2015). Yet, continued sustainability of the Tampa Bay estuary is threatened by projections
of greatly increased human populations and associated stressors by 2050.
BCG analyses of changes overtime can also show year-to-year consistency in ecosystem state,
another indicator of stability and sustainability. Ecosystems that are highly variable from one year
to the next may be more likely to cross a tipping point that would dramatically alter ecological state.
In conditions of high yearly variability in macroalgal bloom biomass, state change may be caused by
an inability of the biological system to recover from low dissolved oxygen, sulfides and other
macroalgal-related toxins (Sutula et al. 2014) when high algal biomass years occur back-to-back.
Incremental changes and feedback loops associated with high macroalgal biomass (Sutula et al. 2014)
or other stressors may also lead to state change.

5. Application of the approach
Sustainable systems have high resilience and low susceptibility. Resilience is defined as, "the capacity
of an ecosystem to absorb disturbance without shifting to an alternative state and losing function
and services" (Holling 1973, Cote and Darling 2010). Using BCG terminology, resilience is the ability
to maintain biological attribute levels when stressors increase, particularly attributes of function
and connectance. Resilient estuaries are characterized by high biodiversity of species and habitats
(relative to expectation for that estuary type). In systems with high species diversity, loss of sensitive
species is compensated by expansions of other species that fill the same ecological roles, and overall
function is retained (Tilman and Downing 1994, Godbold and Solan 2009). High natural connectance
within an estuary may enhance recruitment, recolonization, and movement of species from areas of
high abundance to areas of low abundance, providing a buffering capacity within the estuary to avoid
localized extinctions. The BCG approach offers measures that can serve as proxies for resilience,
e.g., species or habitat-level biodiversity and high connectance.
Susceptibility, when used to describe waterbodies in a BCG approach, is an estimate of the ability
of a waterbody to resist stress based upon physical factors such as hydrodynamics and flushing time
(Bricker et al. 1999, 2007). Waterbody susceptibility may also be affected by temperature, physical
energy, tidal range, depth, or other factors. Some other definitions of susceptibility (often when
resilience is not also considered) do include biological factors (Scavia and Liu 2009). However, in the
BCG construct biology is included in resilience and so susceptibility is limited to non-biological factors
in order to maintain a useful distinction between the two terms. Estuarine BCG levels of condition
use a locally-derived reference for minimally disturbed, so level assignments remain comparable
among estuaries of different physical susceptibilities. Further, estuarine classification by physical
susceptibility (Bricker et al. 1999, 2007) allows BCG comparisons among estuaries of similar
susceptibilities (Section 5.1, page 41).
Recovery potential
Recovery potential is a term used to predict the ability of degraded systems to recover, and the
probability of success in ecological restoration projects. Indicators of recovery potential consider
ecology, stressors, and social factors to evaluate the likelihood that efforts at a specific location will
actually lead to an improved environment. The biological and ecological aspects of recovery potential
consider current and projected stressor loads, stressor-response relationships, resilience, and
susceptibility. Social aspects include political will, community support, funding sources, and existing
infrastructure. Information on recovery potential can be found at

Implementing the Biological Condition Gradient Framework
Sustainability, resilience, susceptibility and recovery potential are interrelated concepts that can be
important to environmental planning and communication. These concepts can be examined through
indices or proxies (e.g., biodiversity), or through rates (and variability) of ecosystem change in the
past, present, or predicted future. The BCG approach helps by providing consistent measurements
of biological and stressor changes over space and time in a waterbody.

6. Results from early pilots
6. Results from early pilots
BCG and BCG-like approaches for estuaries arid coasts are in use or in development by NEPs on all
three marine coasts of the U.S. and in the Caribbean. These NEPs have identified significant benefits
of BCG through the ability to set targets for habitat protection and restoration, and the ability to
engage stakeholders and managers. This section describes NEP efforts as examples of BCG
application and finishes with a sidebar on a very similar approach taken by the European Union.
6.1. Narragansett Bay
Figure 6-1. Narragansett Bay, RI. Note the city of Providence at the northern end of the bay.
Image: Google Earth, data from Landsat

Implementing the Biological Condition Gradient Framework
Narragansett Bay (Figure 6-1) extends almost the full length of Rl and is characterized by a strong
north-south stressor gradient from high anthropogenic impacts in Providence and the northern bay
to less development and significant oceanic influence in the southern Bay. A group of EPA scientists
has been working with the Narragansett Bay Estuary Program (NBEP) and other partners on BCG
development since 2008. A 2009 workshop was attended by representatives of many scientific and
management groups from Rhode Island and Massachusetts including federal and state agencies,
NGOs and private groups, NBEP, and academic organizations (Appendix D). The workshop brought
out tremendous historical knowledge of Narragansett Bay and explored a number of environmental
trends within the Bay. It was a successful starting point by way of gathering information important
to a BCG. However, the diversity of opinion at the workshop together with some misunderstandings
of BCG principles held back a consensus description of a minimally disturbed Narragansett Bay-
which was a workshop goal. A lesson learned from this was that oversight and management of the
Narragansett Bay system was somewhat fragmented, with several influential groups arguing for
different approaches.
The workgroup concluded that building a Narragansett Bay BCG would need to include discussions to
identify common goals of the different user groups. The workgroup also concluded that a next expert
workshop to build consensus on BCG issues would benefit from a narrow set of workshop goals, and
from better informing participants about BCG approaches before the meeting. The Narragansett Bay
workgroup looks at the Puerto Rico Coral Reef workshops as a very successful model, particularly
regarding the instructions and materials that were sent to participants ahead of the meeting to
frame the discussions (Bradley et al. 2014).
Moving forward from the 2009 workshop, the BCG workgroup expanded into a discussion group
and community of practitioners to include EPA scientists working on the coral reef BCG together with
more EPA and non-EPA scientists and managers working in Narragansett Bay. These are the authors
of this document. Within this larger and more national group, the subset of scientists most
interested in Narragansett Bay turned to Greenwich Bay (Figure 6-2, a sub-estuary of Narragansett
Bay) to develop an estuarine BCG demonstration and to test the approach described in this
document. Greenwich Bay has a rich history of change, a high level of public interest, and relatively
abundant social and environmental data.

6. Results from early pilots
Greenwich Bay historical timeline
Figure 6-2. Greenwich Bay, Rl, located mid-bay on the western shore of Narragansett Bay.
Image: Google Earth, data from Landsat
Historical research on Greenwich Bay and the surrounding area led to a historic reconstruction and
trajectory of Greenwich Bay that included cultural history, ecological resources, and stressor impacts
(Pesch et al. 2012). This instructive story was published as an EPA report for a broad public and
scientific audience, and includes guidance for historical research. Figure 6-3 shows a composite of
changes and significant events in natural and anthropogenic stressors in Greenwich Bay together
with qualitative eelgrass abundance, all on the same historic timeline. This merged the natural
and anthropogenic history of the embayment and provided information on a baseline of 'as naturally
occurred'. The biological and stressor data uncovered through this effort were used to develop a
demonstration BCG for Greenwich Bay.

Implementing the Biological Condition Gradient Framework
Little Ice Age
Great Flood Major Nor' Easter
1759 1761
1807 1815 Big Gale
Present Warm Period
1938 1954 Carol
1991 Bob
9 *
Revolutionary War War of 1812
Sediment Quality iso
1820 1840
t	I	I
u u
World War I World War II
1914-18 1941-45
Civil War
B Cu
¦ Pb
s Cr
¦ i
1815 1829 1840 1855 1870 1885 1900 1915 1929 1940 1955/ 1972 1980
Water Quality
Less abundant

7~l T
1st sewer lines WWTF Greenwich Warwick
in East Greenwich in EG Cove closed WWTF
1896	^1928 to shellfishing 1965
Hypoxia in ApponaugCove Greenwich Bay
Apponaug closed to	closed to
Cove shellfishing	shellfishing
1922	1936	1993-1994
fish kill
m GB
—n	1	1	'	
Stonington	Union RR	Warwick RR Electric trolley
Railroad (RR)	Providence	extended to	Providence
built	to Warwick	Buttonwoods to Warwick
1832-37 1865 1881	1910
Figure 6-3. The ecological and cultural history of Greenwich Bay, describing the baseline of undisturbed
together with historic trajectories of stressors and biological responses. Graphic: Pesch et al. 2012
Greenwich Bay BCG
This BCG demonstration (Shumchenia et al. 2015) is a detailed historical account of stressors and
ecological responses over the last two centuries in Greenwich Bay, crafted into a qualitative BCG
using stressor changes over time as the GSA (Figure 6-4). BCG development included
1)	evaluating and selecting biological measures and attributes
2)	defining a minimally disturbed reference condition
3)	synthesizing available data to set thresholds for the six levels of biological response
to stress for each measure/attribute, and
4)	communicating results using the BCG stressor-response diagram (Figure 2-2, page 6).
Consistent narratives for BCG levels (e.g., Appendix A, page 97; Table 4-2, pages 30-31) were used for
thresholds. This allows comparability with new efforts to develop a BCG for all of Narragansett Bay.

6. Results from early pilots
Levels of biological condition
for Habitat Structure
Taxa, indices, and metrics are
as naturally occurs
Some decreases in abundance
of susceptible taxa and/or slight
increases in
Increases in tolerant taxa; slight 2
changes in other metrics
including patterns of vegetation
Evident changes in metrics;
decrease in susceptible taxa
and/or increase in t
evident changes in patterns of
tolerant taxa; 3
Significant changes in many metrics;
marked decreases in abundance of
susceptible taxa (including large and/
or long-lived taxa) and/or evident
increases in tolerant taxa; patterns of
vegetation significantly altered
Many susceptible, sensitive, large and/or
long-lived taxa are absent, with dominance
in abundance of tolerant taxa; shifts in
species diversity; sizes and densities of
remaining species significantly altered;
marked changes in patterns of vegetation
Susceptible, sensitive, large and/or
long-lived taxa are mostly absent, with
extremes in abundance of tolerant taxa;
marked shifts in species diversity and in
size spectra of organisms; marked loss
of natural vegetation may occur
Level of exposure
to stressors
Time 	~
Figure 6-4. Habitat structure BCG model for Greenwich Bay. EG = eelgrass extent; BH = benthic habitat;
PS = primary productivity and shellfish, which are linked in Greenwich Bay. The stressor axis is based on
time periods (top label) that correspond to stressors in Figure 6-3 (page 64); the response axis shows BCG
levels together with narrative threshold guidelines that are consistent with accepted BCG standards.
Graphic: Shumchenia et al. 2015
The BCG development process itself also led to ecological insights. Evaluating seagrass, benthic
communities, primary production and shellfish showed the benefits of including multiple
assemblages. Had the assemblages been examined separately this sub-estuary would have been
evaluated at different BCG levels, showing the importance of more holistic large scale approaches.
Shumchenia et al. (2015) was written to educate managers on the value of BCG for integrating
historical and biological information in setting goals that are supported by the public, and for
supporting decisions on how to achieve those goals. It also serves as an example for practitioners
applying BCG to other waterbodies. The Narragansett Bay group is using this paper to build
management support for a habitat mosaic BCG covering the entire estuary.

Implementing the Biological Condition Gradient Framework
6.2. Tampa Bay
Figure 6-5. Tampa Bay, FL. Image: Google Earth, data from SIO, NOAA, U.S. Navy, NGA, GEBCO
Early public involvement and a BCG-like approach
Tampa Bay (Figure 6-5) is Florida's largest open-water estuary. In the late 1970s environmental
managers and the public grew concerned about macroalgae covering their beaches, phytoplankton
blooms, and loss of marsh, seagrass, birds, fish, and manatees. This led to efforts to better the
condition of the Bay. In 1992, the Tampa Bay Estuary Program (TBEP) was formed to build on this
previous work and serve as a convener to organize different efforts, providing oversight for improving
the Bay. Starting their work before BCG concepts were formalized, TBEP and partners applied a
science-based management approach that is very similar to the estuarine and coastal BCG; in fact,
this estuarine/coastal BCG implementation document drew from key elements of the Tampa Bay
approach, including:
1.	Expert consensus and stakeholder outreach to identify biological measures that are important
to both estuarine function and the public
2.	An overall management approach with a focus on moving the system towards a less disturbed
condition that is closer to the ecological settings under which valued native species evolved
3.	Use of less disturbed time periods in the past as management restoration goals
4.	Expert workshops to assemble data and science for estimating past biological conditions

6. Results from early pilots
5.	Stakeholder consensus workshops to assist in decision-making, e.g., for setting attainable goals
that move the environment closer to a more natural state, while recognizing societal values
6.	A strong investment in public outreach and engagement.
Many of these elements involve the public and other stakeholders. TBEP has used a variety of
methods to engage, include, educate, and motivate these stakeholders, including hosted meetings,
events, public media, informational materials, volunteer opportunities, contests, newsletters
and economic valuations of the bay area (TBEP and TBRPC 2014).
Biotope mosaics and goals
An important TBEP contribution was the development of the biotope mosaic approach (Section
5.4. l.c, pages 51-53) where bioassessment is based on waterbody-wide changes to quantity (acres)
and distributions (relative proportions) of biotopes over time. Establishing 1900 as a minimally
disturbed historic condition for habitat acres, ecological priorities for Tampa Bay were to restore
the balance of critical biotopes to a less disturbed historic benchmark of 1950, with a specific goal
to restore seagrass acreage to that present in 1950 through improvements in water quality. The 1900
minimally disturbed condition and the 1950 goal were developed through consensus of scientists
and stakeholders in 1995.
Restoring the balance - a simple unifying vision
Tampa Bay stakeholders and the public were invested in the quantity and diversity of valued habitats,
and the concept of 'Restoring the Balance' (Figure 6-6) resonated with this community as a simple
unifying vision. The intuitive appeal of this message was effective at communicating estuarine
condition and developing stakeholder visions and goals, which led to management actions and
environmental results. This method can be used together with other approaches as an important
component in the management of estuaries. TBEP has been working with these concepts for many
years (Lewis and Robison 1995).

Implementing the Biological Condition Gradient Framework
New Habitat Restoration Goals
Support a Balanced Approach
The first update of TBEP's Habitat Master Plan in 15 years
was completed in 2010, recommending expansion of
two key habitats — low-salinity salt marshes and salt
barrens — critical to maintaining biodiversity in the bay
The revised Habitat Master Plan validates the original
"Restoring The Balance" approach adopted in 1995,
that called for restoring habitats in relative proportion to
their historic acreages in 1950.
Under "Restoring The Balance," more than 5,000 acres
of coastal wetland and upland habitats have been
restored or enhanced in the Tampa Bay watershed since
1995. Some 7,600 acres of seagrasses, the benchmark
barometer of the bay's health, have been recovered
since 1982. Additionally, 19 of 28 sites priority land
acquisition sites have been completely or partially
purchased, and eight of those have undergone at least
some restoration.
OOMKMmm	«.
6. Results from early pilots
subsequent improvements and progress towards goals. In 2015, Tampa Bay achieved their goal
(set in 1995) of restoring seagrass to the acreage present in 1950, shown as a red star in Figure 6-7.
A historic BCG (or BCG-like approach) offers many insights of value to scientists and managers. Going
further, assigning levels 1 through 6 to Tampa Bay metrics would have led to a BCG framework and
introduced a common language to improve comparisons among Tampa Bay and other waterbodies.
.2	U
1	£
2	-8
_	JS
tj	C
"3d ^
E 75%
\1 angrove/Soartina Area
Saltcorma Area
Seagrass Area
Acrostichum/Juncus Area
1900 1925	1950 1975
Figure 6-7. Biological gradient for biotopes of Tampa Bay. The 2015 attainment of the 1950 seagrass
goal is marked with a star. Graphic: modified from Cicchetti and Greening 2011
Be Floridean
Following water quality and seagrass acreage gains from improved sewage treatment, reduced
atmospheric deposition from power plant upgrades, and improved industrial practices, TBEP turned
to lawn and landscape fertilization as a significant source of nutrient pollution in urban areas of the
Tampa Bay watershed. Reducing these non-point inputs would depend on changing the mindsets
and actions of the individuals and communities who own or maintain outdoor spaces. So, the
"Be Floridian" campaign (Figure 6-8) was launched to positively engage the public to change their
landscaping practices. In "calling on all Southwest Floridians to help protect what makes Florida so
fun", the campaign uses billboards, news releases, community outreach, a flock of travelling painted
flamingos, even Florida DOT (Department of Transportation) road signs (Figure 6-9) that call for
residents to "skip the fertilizer during the summer rainy season", "protect our fun", "Floridify your
lawn", and similar. The program has buy-in from a number of cities, counties, organizations and
communities, the state DOT, and countless individuals. An expansive website with gardening guides
and tips, photo galleries, FAOs, lists of resources, and more can be found at www.befloridian.org.

Implementingthe Biological Condition Gradient Framework
"IBs iiiiiiii&rfkwiil'ifay
Figure 6-8. Be Floridian sign: "This summer I will skip fertilizing my lawn and do the responsible
thing instead: GO HAVE FUN". Image: TBEP, www.befloridian.org
Figure 6-9. Road sign showing FL DOT support of the Be Floridian campaign. Photo: TBEP,
TBEP efforts, based on a combination of approaches to achieve a simple and unifying vision, have
led to habitat gains in Tampa Bay that are widely regarded as a management and restoration success
(Cloern 2001;Tomasko et al. 2005; Duarte 2009; Duarte et al. 2015). In 2015, Tampa Bay achieved
and exceeded their seagrass restoration target of 1950s acreage (TBEP 2015) in large part due to
20-plus years of active engagement and reach-out to involve and motivate stakeholders including
the public, managers, commerce, and other partners (Holly Greening, pers. comm.).

6. Results from early pilots
6.3. Mobile Bay
Figure 6-10. Mobile Bay, AL. Image: Google Earth, data from Landsat and NOAA
The Mobile Bay BCG
Mobile Bay (Figure 6-10) is a relatively shallow estuary with a highly variable salinity regime and a
major deepwater port at the northern head of the Bay. Building a BCG approach for coastal Alabama
is one of the objectives of the Mobile Bay National Estuary Program (MBNEP) in their 2013-2018
Comprehensive Conservation & Management Plan (MBNEP 2013), and the Estuary Program has been
working on BCG well before that. The Mobile Bay BCG assesses changes in estuarine condition based
on indices of habitat distribution and quality along a continuum of anthropogenic stress (Thibaut et
al. 2014). Condition is evaluated and communicated in three levels (good, fair, poor) that are aligned
with BCG narrative. The Estuary Program and partners will use the BCG for monitoring status and
trends, communicating with the public, developing numeric criteria for condition, tracking
management effectiveness, and informing coastal restoration efforts.
Create a clean water future
Along the lines of the TBEP 'Be Floridian' project, MBNEP developed the 'Create a Clean Water
Future' outreach program (Figure 6-11). This is a public service campaign to raise awareness of
stormwater runoff and its impacts, increase political demand for management actions, clean up
trash, and empower individuals and communities with information and tools to reduce polluted

Implementingthe Biological Condition Gradient Framework
runoff from their homes, lawns, and streets. The program promotes the desire for a better future as
an inspirational message and provides a number of resources that communities and individuals can
use to reach out to others (see www.cleanwaterfuture.com). MBNEP recognized that changing the
day-to-day actions of residents is critical for reduction of non-point source pollution and that
motivated citizens are a powerful force in environmental improvement (Figures 6-11, 6-12, and 6-13).
Public outreach and incorporating the priorities and values of local stakeholders are central tenets of
the Estuary Program's work.
Clean Water
Figure 6-11. Create a Clean Water Future campaign-changing public attitudes to protect Mobile Bay.
Image: MBNEP
Figure 6-12. Natural beauty of Three Mile Creek, Mobile Bay, AL. Photo; MBNEP

6. Results from early pilots
Figure 6-13. Another image from Three Mile Creek, Mobile, AL, illustrating the need to change
public actions, and the need for the Clean Water Future campaign. Photo: MBNEP
Habitats, ecosystem services, and restoration
MBNEP, in partnership with The Nature Conservancy and NOAA, used NOAA's Habitat Priority
Planner to identify priority habitats throughout coastal Alabama. Through a year-long process of data
gathering and evaluation, MBNEP's Coastal Habitats Coordination Team identified 10 priority habitats
in need of preservation or restoration. During 2010 planning for the current CCMP, the MBNEP's
Science Advisory Committee evaluated the ability of each of these habitats to provide ecosystem
services at different levels of impact from a suite of stressors. Freshwater wetlands, streams, rivers
and riparian buffers, intertidal marshes, and flats were most stressed, primarily due to habitat
conversion. The BCG is used to measure changes in condition of these habitats due to restoration
efforts. This BCG also includes ecosystem services analyses to communicate the importance and
value of loss or improvement in habitat condition.
Going further
MBNEP is initiating a program for high resolution mapping of habitats to establish present-day
baselines for acreage and distribution of critical habitats (including seagrasses), with continued
monitoring for change. A later action would be to develop numeric criteria for habitat condition.
Also, an existing restoration effort in Mobile Bay's D'Oiive watershed is being used as a pilot to
develop and test a conceptual model to measure levels of ecosystem services as related to changes
in stressor levels. Restoration success here may guide the re-establishment of once-present seagrass
beds downstream. The BCG would be used to quantify this and other changes as well as to
communicate results in a way that resonates with stakeholders and informs further restoration
actions. MBNEP is building a comprehensive approach that effectively incorporates BCG into
management of Mobile Bay, and is developing these tools for transferability to other areas on
the Alabama coast.

Implementing the Biological Condition Gradient Framework
6.4. Lower Columbia River
Figure 6-14. The Lower Columbia River, which forms much of the border between Oregon
and Washington. Image: Google Earth, data from Landsat
The Lower Columbia River Estuary (Figure 6-14) is the 146 mile tidally-influenced reach of the
Columbia River from the Bonneville Dam (which is about 100 river miles east of Figure 6-14) to the
Pacific Ocean. The Lower Columbia Estuary Partnership (LCEP) uses the BCG to evaluate ecosystem
condition and to develop quantitative environmental targets for different areas of the river, thus
improving management of this system.
Engaging stakeholders and developing a vision
LCEP actively engaged and involved communities and stakeholders throughout the process of
articulating a holistic vision, determining objectives, and setting quantitative management targets.
Communicating and implementing the resulting plan was then a collaborative effort with these initial
partners. LCEP now practices adaptive management by monitoring to ensure that environmental
goals are met and reports results back to the involved communities and stakeholders. This approach
adopts the principles of both EBM and SDM (Section 5.3, pages 45-46).
Through this process, biological integrity and habitat loss/modification were identified as
management issues significant to the region, and were addressed in the Estuary Partnership's
Management Plan. A vision and goals (LCEP 2012) were developed as:
- Integrated, resilient, and diverse biological communities are restored and maintained in the
Lower Columbia River and estuary.

6. Results from early pilots
- Habitat in the Lower Columbia River and estuary supports self-sustaining populations of plants,
fish, and wildlife.
Moving to deliver on this vision, the Partnership has devoted significant time and resources to
address biological integrity and habitats using a BCG approach.
LCEP organized a two-day workshop in April 2012 with EPA support to define 'minimally disturbed'
and identify attributes specific to the estuary (Corbett 2012). Workshop participants specified
attributes including 1) natural habitat diversity, 2) focal species (e.g., Pacific salmon and steelhead),
3) water quality, and 4) ecosystem processes. While LCEP did not name their attributes in the
terminology of BCG (e.g., Table 4-2, pages 30-31), they identify stakeholder management priorities
which could easily be translated into specific BCG attributes. To address LCEP attribute 1 (natural
habitat diversity) the Partnership has identified priority habitats (including several classes of wetlands
and vegetation-based shore habitats) for protection and restoration based on past habitat coverage;
this is the BCG 'Structure' attribute and serves as a proxy for the 'Function' attribute.
Figure 6-15. Prairie Channel (WA) and the natural beauty of the Lower Columbia Estuary. Photo: LCEP
Quantitative targets
This group completed an extensive habitat change analysis comparing 1870 to 2009 land cover and
developed quantitative habitat coverage targets for native habitats based on past habitat extent
using species-area curves (MacArthur and Wilson 1967). The targets include 1) no net loss of native
habitats as of the 2009 baseline, 2) recover 30% of the historic coverage of priority habitats by 2030,
and 3) recover 40% of the historic coverage of priority habitats by 2050. By meeting these targets
the Lower Columbia River will have regained between 46-88% of its historic habitat coverage by
2050, depending on river reach, with an average of 60% historic habitat coverage. The Partnership's
next task is to identify "anchor areas" for larger protected reserves, a minimum number of reserves,
and important locations for filling habitat gaps and migratory corridors (i.e., connectance).

Implementing the Biological Condition Gradient Framework
The Estuary Partnership is in the process of developing numeric and spatially explicit targets for the
other three attributes. Focal species (LCEP attribute 2) were identified in the 2012 workshop, and the
Partnership has been developing draft targets for this attribute, particularly for juvenile salmonids,
a group of primary importance to the region (Corbett 2013).
Consensus and communication
The Partnership recognizes that quantitative targets, though they require a significant development
effort, are very effective tools for environmental improvement. Further, quantitative targets
promote Partnership goals within the larger competitive political landscape, and are an important
communication tool both for managers and the public (Corbett 2013). The Estuary Partnership has
made important strides in advancing BCG implementation, and continues to develop their plan,
emphasizing consensus and communication among stakeholders so that science-driven targets
are well-received and supported (Figure 6-16).
Figure 6-16. Stakeholder investment: paddlers on the Lower Columbia Estuary. Photo: LCEP

6. Results from early pilots
6.5. Puerto Rico coral reefs
Figure 6-17. The stretch of reefs from La Parguera to Guanica Bay, southwestern PR, the area of data
collection for the coral reef BCG. Note the heavily agricultural landscape. Image: Google Earth, data from
Coral reefs are unique ecosystems in decline
The southwestern Puerto Rico coast (Figure 6-17) is a patchy assortment of cays, coral reefs,
mangroves, seagrasses, and beaches known for snorkeling, scuba diving, and nature tourism.
Coral reefs, like estuaries, are complex coastal ecosystems made up of many closely linked habitats
that interact with other adjacent habitats. Connectance is high in functioning coral reef systems.
Mangroves and seagrasses, for example, strongly influence the community structure offish on
neighboring coral reefs (Figure 6-18, Mumby et al. 2004). These adjacent vegetated habitats also
improve water quality on nearby reefs by trapping sediments, nutrients and pollutants (Grimsditch
and Salm 2006). Coral reefs are the most biologically diverse marine ecosystems on earth and rely
on the interaction of many species including hard and soft corals, marine invertebrates, and fishes
(Sebens 1994, Odum 1997, Bradley et al. 2010).
Sadly, coral reef ecosystems are rapidly declining, in large part due to human activities including
agriculture and land use practices that lead to polluted runoff, overfishing, temperature change, ship
groundings and coastal development. Recognizing the importance and fragility of coral reefs, the
United States Coral Reef Task Force (USCRTF) was established by Presidential Executive Order in 1998
to conserve coral reefs, and includes 12 Federal agencies, a number of states and territories, and
many other partners. The Task Force selected Guanica Bay, Puerto Rico, as the first pilot of their
Watershed Initiative.

mplementing the Biological Condition Gradient Framework
Figure 6-18. Diagram showing ecosystem connectance between mangroves, seagrasses, and coral reefs
for different life history stages of a species of grunt. Label (A) shows juvenile grunts in a seagrass bed. Upon
reaching a certain size the fish move to mangroves (B). The mangroves serve as a nursery habitat as fish
further increase in size and migrate to patch reefs {C), then shallow fore reefs (D), and finally high relief reefs
(E). As adult grunts spawn on these high relief reefs their larvae {shown above in the upper water column)
grow into juveniles that move into seagrasses (A). If mangroves {B) are not present, grunts on patch reefs
{C) are smaller and significantly less abundant. Other species (F) including some parrotfishes {shown in orange
and green here) are more dependent on mangroves, and are not seen when mangroves are absent.
This connectance could be evaluated using a habitat mosaic approach. Graphic: Mumby et al. {2004),
reprinted with permission from Nature.
Workshop: Decision support, SDM, and DPSIR
Working with the USCRTF prior to developing a coral reef BCG for Guanica Bay, the EPA Office
of Research and Development and colleagues co-hosted a decision support workshop in 2010,
inviting decision makers, scientists, and stakeholders (Bradley et al. 2015). Goals were to facilitate
participants to:
-	Look at the watershed as a system
-	Share a collaborative vision for sustainable coral reefs
-	Initiate a systematic, deliberative process to analyze coastal and watershed decisions
that impact coral reefs and other ecosystems that provide services to humans
-	Advance an integrative framework to incorporate the ecological, social, economic and
legal consequences of alternative decisions.
This workshop used SDM and DPSIR to build consensus for management of the Guanica Bay
watershed, using SDM tools including an objectives hierarchy (Section 5.3, pages 45-46) and
a Social Network Analysis (Section 3.2, page 14) to better understand and improve stakeholder
communications, and an advanced online SDM/DPSIR tool (DASEES, www.dasees.org) to organize
the process. This work set the stage for development of a BCG. Bradley et al. (2015) present a
detailed report on the process and outcomes of the workshop.

6. Results from early pilots
Coral reef BCG
Moving forward from this foundation, EPA developed a conceptual narrative model and BCG
approach to describe how biological attributes of coral reefs change along a gradient of increasing
anthropogenic stress. The approach also identifies the critical attributes of coral reefs and evaluates
how each attribute changes in response to stress. This BCG assists decision-makers in understanding
the current conditions of Puerto Rico coral reefs relative to natural, undisturbed conditions. Decision
makers can then set realistic goals for their coral reefs, and establish monitoring (measurement)
endpoints based on attributes identified by the scientific community (Bradley et al. 2014).
Workshop: Biological integrity and levels of condition
To develop this BCG, EPA hosted an expert consensus workshop in 2012 (Bradley et al. 2014). Invited
scientists evaluated photos and videos collected by EPA and partners at 12 stations from Puerto Rico
coral reefs exhibiting a wide range of conditions. The experts individually rated each station for
observed condition ('good', 'fair' or 'poor') and documented their rationale for the assignment
(Figure 6-19).
Figure 6-19. EPA coral reef sites reflect a range of coral reef conditions, from good (left) to fair (middle),
to poor (right).
The group further identified the attributes that characterize high biological integrity (or natural
condition) for Puerto Rico's coral reefs. A BCG based on hard corals, fishes, gorgonians, sponges,
and other critical biota was developed for shallow-water linear reefs of southwestern Puerto Rico
(Bradley et al. 2014). The experts were able to identify and develop narratives for four distinct levels
of condition: very good-excellent, good, fair, and poor as shown in Table 4-2 (pages 30-31), a
qualitative but very useful approach. Going further, a quantitative BCG was later developed for
fish species based on decisions of a BCG panel using analyses of numeric fish data.

Implementing the Biological Condition Gradient Framework
Table 6-1. Summary descriptions of four coral reef condition categories (very good/excellent to poor)
based on expert assessments of individual stations. The description of Very good/excellent' condition is
based on panelist determination of features expected in very good stations (Bradley et al. 2014).
Condition Level
Attribute descriptions
BCG level 1-2)
Physical structure: High rugosity or 3D structure, substantial reef built above bedrock, many
irregular surfaces provide habitat for fish, very clear water, no sediment, floes or films
Corals: High species diversity including rare; large old colonies (Orbicella) with high tissue
coverage; balanced population structure (old and middle-aged colonies, recruits); Acropora
thickets present
Sponges: Large autotrophic and highly sensitive sponges abundant
Gorgonians: Gorgonians present but subdominant to corals
Condition: Low prevalence disease, tumors, mostly live tissue on colonies
Fish: Populations have balanced species abundance, sizes and trophic interactions
Vertebrates: Large, long-lived species present and diverse (turtles, eels, sharks)
Other invertebrates: Diadema, lobster, small crustaceans and polychaetes abundant, some large
sensitive anemone species
Algae/plants: Crustose coralline algae abundant, turf algae present but cropped and grazed by
Diadema and other herbivores, low abundance fleshy algae
BCG level 3)
Physical structure: Moderate to high rugosity, moderate reef built above bedrock, some irregular
cover for fish habitat, water slightly turbid, low sediment, floes or films on substrate
Corals: Moderate coral diversity; large old colonies (Orbicella) with some tissue loss; varied
population structure (usually old colonies, few middle aged, and some recruits); Acropora thickets
may be present; rare species absent
Sponges: Autotrophic species present but highly sensitive species missing
Gorgonians: Gorgonians more abundant than level 1-2
Condition: Disease and tumor presence slightly above background level, more colonies
have irregular tissue loss
Fish: Decline of large apex predators (e.g. groupers, snappers) noticeable; small reef fish
more abundant
Vertebrates: Large, long-lived species locally extirpated (turtles, eels)
Other invertebrates: Diadema, lobster, small crustaceans and polychaetes less abundant than
level 1-2; large sensitive anemones species absent
Algae/plants: Crustose coralline algae present but less than level 1-2, turf algae present and
longer, fleshier algae present than level 1-2
BCG level 4)
Physical structure: Low rugosity, limited reef built above bedrock, erosion of reef structure
obvious, water turbid, more sediment accumulation, floes and films; Acropora usually gone,
present as rubble for recruitment substrate
Corals: Reduced coral diversity; emergence of tolerant species, few or no large old colonies
(Orbicella), mostly dead; Acropora thickets gone, large remnants mostly dead with long uncropped
turf algae
Sponges: Mostly heterotrophic tolerant species and clionids
Gorgonians: More abundant than Levels 1-3; replace sensitive coral and sponge species

6. Results from early pilots
Table 6-1 (continued)
Condition Level
Attribute descriptions

Condition: High evidence of diseased coral, sponges, gorgonians; evidence of high mortality,
usually less tissue than dead portions on colonies
Fish: Absence of small reef fish (mostly damselfish remain)
Vertebrates: Large, long-lived species locally extirpated (turtles, eels)
Other invertebrates: Diadema absent; Palythoa overgrowing corals; crustaceans, polychaetes and
sensitive anemones conspicuously absent
Algae/plants: Some coralline algae present but no crustose coralline algae; turf is uncropped,
covered in sediment; abundant fleshy algae (e.g., Dictyota) with high diversity
BCG level 5-6)
Physical structure: Very low rugosity, no or little reef built above bedrock; no or low relief for fish
habitat; very turbid water; thick sediment film and floes covering bottom; no substrate for recruits
Corals: Absence of colonies, those present are small; only highly tolerant species, little or no tissue
Sponges: Heterotrophic sponges buried deep in sediment, highly tolerant species
Gorgonians: Small and sparse colonies, mostly small sea fans, often diseased
Condition: High incidence of disease on small colonies of corals, sponges and gorgonians,
if present
Fish: No large fish, few tolerant species, lack of multiple trophic levels
Vertebrates: Usually devoid of other vertebrates other than fishes
Other invertebrates: Few or no reef invertebrates, high abundance of sediment dwelling
organisms such as mud-dwelling polychaetes and holothurians
Algae/plants: High cover of fleshy algae {Dictyota); complete absence of crustose coralline algae
and rarely calcareous algae
Lessons from this coral reef workshop that apply to other BCG workshops are:
1.	The heightened contributions of motivated participants who care deeply about the
resource and who are committed to bioassessment as a management tool.
2.	The value of easily communicated measures of biology, e.g., visual assessment methods
that can be distributed as images for participant review before the workshop.
3.	The importance of thorough workshop pre-planning.
This workshop is described and discussed in Bradley et al. (2014).
Public Values Forum: Involving stakeholders in management decisions
The EPA group positioned this BCG in the USCRTF pilot effort in Guanica Bay to communicate
biological condition as part of a larger management effort. EPA further hosted a Public Values Forum
for stakeholders in Guanica Bay during the summer of 2013. Goals of this forum were to identify
stakeholder values, objectives, and performance measures, then prioritize management actions
to address stakeholder and public values. Anonymous electronic voting tools were used to gather
immediate, individual, and inclusive feedback. Stakeholders also developed a preliminary

Implementing the Biological Condition Gradient Framework
consequence table-a matrix of management alternatives vs. effects on values or concerns
(Bradley et al. 2016). This allowed EPA and partners to frame the issues, understand citizen values
and perceptions, engage stakeholders, clarify the decision landscape, and develop stakeholder
objectives. Together with BCG and previous SDM work, this led to effective management decisions
important to, and supported by, stakeholders. The forum is reported in Bradley et al. (2016) along
with a section on decision support tools.
Summary - Puerto Rico
These efforts in Puerto Rico followed a clear logic path through a series of stakeholder workshops:
first, the 2010 Decision Support workshop identified stakeholder objectives and measures using SDM,
an objectives hierarchy, and DPSIR; next, a workshop in 2012 developed a BCG as the scientific basis
for reef management; then, the Public Values Forum in 2013 elicited stakeholder values to further
inform the decision process. This path closely parallels the BCG implementation steps we present
here, but moves the process further into stakeholder-based management at a regional and water-
shed scale. These efforts are well documented in a number of U.S. EPA reports and publications
which serve as detailed examples for estuarine and coastal BCG practitioners. The EPA played a
very significant role in shaping decision-making in the Guanica Bay watershed as part of the large
interagency USCRTF effort. This work takes implementation of the BCG to a high level in supporting
management decision-making in coastal areas. While smaller management programs may not have
the equivalent funding to replicate these efforts, the sequence of activities taken in Puerto Rico could
be successfully enacted on a smaller scale with fewer resources.
Another example - waterbody management in the European Union
The twenty-eight countries in the European Union (EU) have been using a BCG-like approach to
manage their waters since the 2010 enactment of the EU Water Framework Directive (WFD), and
this body of work is relevant and instructive to estuarine and coastal BCG development in the
United States. EU Member States (countries) use the agreed-upon WFD to assess their coastal
and estuarine waters. The Directive applies core BCG concepts in a series of steps.

6. Results from early pilots
Six required steps for managing European estuaries
1)	The DPSIR framework with a 'pressures and impacts assessment' is used to evaluate
environmental problems.
2)	Waterbodies are classified into one of six 'categories' (rivers, lakes, estuaries, coasts, artificial
waterbodies, and heavily modified waterbodies), then each category is further classified into
'types' of similar systems to improve comparability. Types are determined using a hierarchy
of classification factors.
Obligatory Factors:
-	Ecoregion
-	Tidal Range
-	Salinity
Optional Factors for estuaries, in the following order if possible:
-	Mixing
-	Intertidal Area (%)
-	Residence Time
-	Other Factors (Depth, Current Velocity, Wave Exposure, etc.)
3)	Biological elements (a bit more prescriptive than BCG attributes) can be evaluated using any
method suited to the situation. All elements must be assessed.
Biological elements for estuaries:
-	Composition, abundance, and biomass of phytoplankton
-	Composition and abundance of other aquatic flora
-	Composition and abundance of benthic invertebrate fauna
-	Composition and abundance of fish fauna
4)	Type-specific reference conditions for biological elements are defined using a hierarchy
of methods, identical to those used in U.S. bioassessments (Gibson et al. 2000):
-	Comparison to an existing undisturbed site or
one with only very minor disturbance (preferred)
-	Use of historical data or information
-	Models
-	Expert Judgement
5)	Assignment of ecological status classes (High, Good, Moderate, Poor and Bad) to biological
elements is anchored in the type-specific reference condition and is based on consistently
defined narratives. This is analogous to the BCG approach, although the WFD formalizes
intermediate steps and applies an intercalibration process to assure that status class thresholds
have consistent meaning among Member States.
6)	The status classes are used with the DPSIR analyses (Step 1) in planning and decision-making.
Overall ecological status of the waterbody is defined as the lowest status of any of the four
biological elements, considering also (but to a lesser degree) status of hydromorphological and
physico-chemical elements. Waterbody thresholds between Good and Moderate (also between
High and Good) lead to sets of actions that must be taken by Member States to protect and
improve their waters.

Implementing the Biological Condition Gradient Framework
The WFD allows flexibility in methods for assessing condition and determining reference, but is
designed for comparable assessment and regulation across Member States and so is significantly
more prescriptive than the BCG we present here. The document (EC 2002) at
is an excellent guidance report for the European approach, with many lessons for applying the
BCG to estuaries and coasts on our side of the Atlantic. If you go to this document, take note of
terminological differences, particularly with 'typology' and 'classification'. Other WFD guidance
documents describing every stage of the process in detail can also be accessed as pdfs on
the internet.
The coastal and estuarine BCG and similar approaches have been used to manage a number of
waterbodies. Each case study is different, to address a variety of research and management needs.
Together, they provide a tremendous resource of ideas and insight for those considering or
implementing BCG methods.

7. Summary and next steps
Figure 7-1. Photo montage of public/stakeholder interest in estuaries and coasts. Clockwise from top left:
1) Manatees are a boon to tourism, Weeki Wachee River, FL. Photo: N. Cicchetti 2) Shallow water coral reef
scenes attract snorkelers, Florida Keys National Marine Sanctuary. Photo: NOAA 3) Recreational boating and
fishing are popular activities, Everglades City, FL. Photo: NOAA 4) Young beachgoers and a swimmer enjoying
the water, Charlestown, Rl.
7. Summary and next steps
Biological tools for managing estuaries and coasts
The BCG is the U.S. EPA approach to bioassessment and positions biology as a central element in
environmental management and decision making. BCG levels provide a 'common language' that
allows consistent biological assessment of waterbodies at different times, scales or locations.
The BCG stressor axis helps identify and address degradations due to cumulative impacts of many
stressors or due to specific impacts of individual stressors. This guidance document provides a
toolbox of actions to address management needs and build a BCG to solve environmental problems
in coasts and estuaries.

Implementing the Biological Condition Gradient Framework
Core aspects of developing an estuarine and coastal BCG for any system or area are to:
1.	Build public and stakeholder consensus, evaluate environmental problems, important stressors,
management needs, stakeholder needs, and available data to define the biological measures
and attributes that will best assess biological condition for the problems at hand.
2.	Apply expert consensus to define undisturbed and minimally disturbed conditions. Develop
narratives for BCG levels and use the narratives to support non-regulatory management needs,
including stakeholder engagement, visioning, target setting, assessments, and monitoring.
3.	Use expert best professional judgment to develop numeric decision rules and thresholds for
each level. Apply the BCG to management needs, both non-regulatory (e.g., increased impact
of all the above actions) and regulatory (e.g., state CWA actions or TMDLs). Use specific
stressor-response models, further stakeholder input, adaptive management, and other tools
as applicable.
Future development of estuarine and coastal BCG
New and continued use of BCG by management programs is by far the most effective way to improve
and expand this approach. Current adopters (Section 6 above) have shown many different ways to
use these methods, and will continue to innovate. The estuarine and coastal BCG is intended as a
flexible set of concepts and tools; new programs will select and develop those aspects best suited
to their particular situations and needs. This adds to the experiences of a community of users and
the approach will grow through a better understanding of what works in a variety of ecological,
social, and political settings.
Moving forward, a workgroup of scientists and managers (including the authors ofthis document)
continues to develop and promote BCG in estuaries, coral reefs and other complex systems. This
group has been active and growing since 2008. BCG projects for managing specific coastal and
estuarine waterbodies are underway in many areas across the country. Each application addresses
a different set of problems and explores a different approach to environmental management but the
goal for all projects is to improve decision-making by bringing biology and BCG methods into direct
use by managers. The workgroup is also addressing priorities identified as important for further
development of the estuarine and coastal BCG and its implementation.
One priority is to better develop the GSA (the BCG X axis). A detailed stressor gradient can improve
links between specific stressors and the resulting biological responses. When these relationships are
quantitative, BCG can inform target setting for reduction of specific stressor levels and guide related
management actions. Integrating these individual stressors-response measures into a well-
developed quantitative GSA (with its own measures and proxies that evaluate cumulative impacts)
would better define the entire stressor field to which biota is exposed and so improve both
management and communication.
On the biological condition axis (the BCG Y axis) the workgroup continues to explore the use of
higher attributes such as function and connectance to provide more comprehensive assessments

7. Summary and next steps
of waterbody condition. Developing more effective and easily attained measures of these attributes
would allow EPA and others to better address questions of waterbody sustainability and resilience.
This would be particularly applicable in degraded parts of estuaries where structure and composition
are so severely altered that improving function becomes the priority for restoration and management.
This information may in turn help human communities adapt to the effects of global change
(Figure 7-2).
Biotope mosaics are being explored as a way to evaluate function and connectance, and interest
in this approach has been growing. New stressors leading to biotope losses, including sea level rise,
are of growing concern. Mosaic measures are inherently quantitative, and work to consistently
assign values of measures to BCG levels would be a valuable contribution to application of the
method. This would require input from national experts working in different types of systems
at different stages of degradation.
Figure 7-2. Eroding marsh edge, which can be a cause of marsh loss due to sea level rise.
Lower Chesapeake Bay, VA,
Another interest is in improving tools that engage stakeholders in developing visions for desired
future estuarine conditions and in setting environmental goals. Proven tools such as facilitated
workshops and public fora may be supported by new tools such as electronic polling, Social Network
Analyses (SNA), and outreach through electronic or visual media. Other priorities include exploration
of more efficient sampling technologies including remote sensing of biology, which has potential
to change the scale at which we assess our coasts and estuaries. Further, better approaches to
estuarine classification-that specifically integrate the stressorfield and biological response-could
improve transfer of knowledge and practice among estuaries and estuarine managers.
Local or national expert workshops can refine implementation of the BCG to best meet management
needs and will contribute to addressing the issues listed above. The coastal/estuarine BCG work-
group has started to evaluate the need for national workshops to assist all BCG practitioners and
improve management applications. In fact, well-organized workshops have been indispensable in
advancing local and national efforts from the very beginning of the Office of Water BCG program.

Implementing the Biological Condition Gradient Framework
The estuarine and coastal BCG approach has an intuitive appeal to the public and other stakeholders.
The focus on living things has a clear connection to the human experience, as does the concept of
looking at changes over time. Linking stressor increases over historic time to losses of valued species,
habitats, and functions leads to collaborative goal-setting as 'what did we have, what do we have,
and what do we want', an approach that can resonate with people. Comparing existing condition
to natural condition makes intuitive sense, and people like to see evaluations of an entire waterbody
rather than just a part of it. This human appeal can engage citizens to participate in discussions
to identify biological measures they value and set targets for improving the condition of those
measures. A motivated public is a powerful driver of environmental change through their actions,
communications, volunteerism, and ability to increase political will. Engaging the public and
other stakeholders is a primary focus of the estuarine and coastal BCG.
Applicable at any scale or at multiple scales using one or several attributes, BCG is an effective and
flexible approach to bioassessment and environmental management. The ability to consistently
compare biology over time and location offers many advantages. The BCG is firmly entrenched
and supported within the U.S. EPA Office of Water and can be used in combination with other
management frameworks. A number of management groups have successfully applied the BCG
(or similar methods) to address the problems facing their waterbodies.
Increased use of the BCG in programs around the nation has inspired other groups to look into the
approach. This document proposes guidance for estuarine and coastal BCG implementation as a
logical set of actions to engage stakeholders, scientists, and managers in solving problems and
managing complex systems. NEPs, NGOs, states, and other interested parties are urged to contact
current users, the authors of this report, or the Office of Water bioassessment program for further
discussions and assistance.

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Appendix A
Appendix A. Attributes and narratives to assign BCG lewels in streams
Table A-l. Ecological attributes and possible measures (first three columns) paired with example narratives for BCG levels
(last 6 columns), from U.S. EPA (2016).
Structure arid
(Attributes I-V)
See Table AI-2
for detailed
descriptions of
these attributes
Community or habitat
structure and complexity.
May also recognize loss of
habitats or species due to
human activities.
Examples include
macroinvertebrate or fish
indices, phytoplankton or
zooplankton community
measures, epifaunai
measures, biotope
presence/quantity of
sensitive taxa or biotopes,
wetland vegetative
indices, etc.
composition is as
naturally occurs,
except forgiobat
extinctions based
on observations
from water bodies
with similar habitat
and ecoregion
measurable human-
caused stressors
(this includes
chlorophyll a levels,
biotope mosaics,
including large,
long-lived, and
sensitive species;
patterns of
vegetation are as
naturally occurs)
i sensitive species
Most sensitive,
large and/or long-
lived taxa are
absent, with a
abundance of
tolerant taxa;
species <
size, and densities
of remaining
species; biotope
mosaic significant^
altered with many
evident loss in
biotope or habitat
Sensitive, large,
and/or long-lived
taxa largely absent;
possible high or low
extremes in
abundance of
remaining taxa;
marked reduction in
species diversity
and in size spectra
of remaining
organisms; near
complete loss or
alteration of natural
biotope mosaic with

mplementing the Biological Condition Gradient Framework
Table A-l (continued)

Examples of BCG



Status of non-native
Non-native taxa, if
Non-native taxa
Ncn-native taxa
Some assemblages
Same as level 5; not

species. May include
present, do not
may be present, but
may be prominent
abundance of
(e.g., mollusks,

measures of the impact of
significantly reduce
occurrence has a
in some
tolerant non-native
based on non-native

invasive and non-native
native taxa or alter
assemblages (e.g.,
species (e.g.,
mscrophytes) are
species atone

structural or
effect on native
Common Carp, non-
dominated by


Examples include
functional integrity
bivalves, fish) and
native centrsrchids.
invasive non-native

estimated numbers of

some sensitive
Common Reed} or
taxa {e.g.. Silver

speciesor individuals,

native taxa may be
native species {e.g.,
Carp, Zebra

(Attribute VI)
relative density or

reduced or replaced
saimonids) only
Mussels, Eurasian

biomass measures of
nativesand non-natives.,
orreplseement of native

by equivalent non-
native species (e.g.,
replacement of
maintained by
WatermUfoiJ); or
dominance by


native trout with

tolerant non-native


species such as
Common Carp

Measures condition of
Diseases and
Incidences of
Incidences of
Disease outbreaks
Host species in

individual organisms,
anomalies are
anomalies are
diseases and
are increasingly
which diseases and

including anomaties and
consistent witli
consistent with
anomalies may be
anomalies are
common, anomalies
anomalies have

naturally occurring
naturally occurring
siightly highe r than
slightly higher than
are increasingly
been observed are

Examples include external
incidents and
incidents and
expected conditions
expected. For
now absent, so

anomalies, lesions,

example, corai
particularly in kmg-
diseases might be

disease outbreaks {local or

bleaching events
fived taxa where
difficult to detect.

widespread), coral

may occur
faiornass may afco
Ancmalies, disease,
(Attribute VII)
bleaching, seagrass

sporadically and
be reduced (e.g.,
etc.-may occur
condition, fish pathology,
and frequency of diseased

result in sirghtly
elevated mortality.
bleaching events
are frequent
across multiple
species or taxa
or affected organisms

Anomalies in fish
occur in a small
fraction of a
enough to cause
mortality of corals).
Anomalies, such as
erosion, lesions, and
tumors in fish, occur
in a measurable
fraction of a

Appendix A
Table A-l (continued)


s of BCG



Measures of energy flow.
Energy flows,
Energy flows,
Virtually alt
Most functions are
loss of some
Most functions

trophic linkages and
material cycling.
material cycling,
functions are
maintained through
ecosystem functions
show extensive and

material cycling. They may
and other functions
and other functions
maintained through
are manifested as

include proxy or snapshot
areas naturally
are within the
redundant system
changed export or
disruption, shifts to

structural metrics that
natural range of
redundant system
attributes, though
import of some
primary production.

correlate to functional
characterized by
attributes, minimal
there is evidence of
resources and

characterized by
changes to export
loss of efficiency
changes in energy
dominance, fewer
Examples include
interactions and
and other indicative
(e.g., increased
exchange rates
and shorter-length
{Attribute Viit)
long-lived links
interactions and
functions. Some
export or decreased
trophic links and

respiration ratios, benthic:
supporting targe,
long-lived links
functions increased
import, there may
respiration ratios.
highly simplified

pelagic production rates.
supporting large.
due to pollution or
be shifts in benthic;
benthic: pelagic
trophic structure,

chlorophyll a
low levef
pelagic production
production rates.
marked shifts in


disturbance (e.g.,
respiration or
benthic: pelagic

macroafgal biomass.


production rates

bacterial biomass and





Measures of a landscape's
N/A—A natural
Limited to small
Limited to a local
Mild detrimental
Detrimental effects
Detrimental effects

capacity, contributing
disturbance regime
pockets and short
area orwithln a
effects may be
extend far beyond
may eliminate all

surface water to a single
is maintained
detectable beyond
the focal area
refugia and

location, to maintain the

the local area and
leaving only a few
colonization sources

fuli range of ecological

may include more
isSands of adequate
within a regionor

processes and function

than one season
conditions; effect
catchment and

Spatial and
that support a resilient.

extends across
affect multiple
naturally occurring

multiple seasons
Ertent of
aquatic community. The

functions and processes to

(Attribute IX)
be measured include
hydroiogic regulation,
regulation of water
chemistry and sediments,
hydroiogic connectivity
(see also attribute X),
temperature regulation,
and habitat provision


Implementing the Biological Condition Gradient Framework
Table A-l (continued)

Examples of 6CG



Observations of exchange
System is naturally
System is naturally
Slight loss, or
Some loss, or
Significant loss, or
For many groups, a

or migrations of biota
connected, or
connected, or
increase, in
complete loss in

between adjacent water
disconnected, in
disconnected, in

bodies or habitats.
space and time,
space and time,
between adjacent
between adjacent
connectivity in at

important measures
water bodies or
water bodies or
between adjacent
least one dimension

within the area being
migrations, and
migrations, and
habitats (e.g.,
habitats (e.g.,
water bodies or
(either spatially or

studied may be strongly
recruitment from
recruitment from
between upstream
between upstream
habitats {e.g.,
temporally) lowers

affected by factors
adjacent water
adjacent water
and downstream
and downstream
between upstream
reproductive or

adjacent to or iarger than
bodies or habitats
bodies or habitats
water bodies), but
water bodies), but
and downstream
recruitment success

the immediate study area.
are as naturally
are as naturally
water bodies or
or prevents

Metrics may include
sources, refugia.
sources, refugia,
habitats) Is evident;
migration or

dams, causeways,

and other
and other
exchanges with

fragmentation measures,

mechanisms mostly
sources do not exist
adjacent water
hydrologies! measures, or

compensate. May
prevent complete
for some taxa, some
bodies or habitats,
proxies such as

also be increase in
disconnects or
{Attribute X)
characteristic migratory

connectivity due to
other failures
disconnects or
disconnects or


canals, interbasin

connect exist
other failures. For
other groups, a
complete loss in
disconnect in at
least one dimension
lowers reproductive
or recruitment
success (e.g.,
predatfon of
amphibians by fish
in once isolated
headwater streams)

Table A-2. Detailed matrix of Taxonomic Composition and Structure Attributes l-V for streams
(compressed into 'Structure' in Table A-l), from U.S. EPA (2016).

BCG Levels
Natural or native
Minimal changes in
Evident changes in
Moderate dianees
Maior changes
Severe chances in
the structure of the
structure of the
in structure of the
biotit rommimitv
and minimal
structure of the
structure of the
Native structural,
functions!, and
taxonomic integrity
is preserved;
ecosystem function
is preserved within
the range of natural
hiofir rommunitu
and minimal
bintir rrnmmi initv
and minimal
bintir rnmnvinitv
and moderate
hiotir mmmunitv
rhsnooc in
ecosystem function
ecosvstem function
rhanw<; ,n
ecosvstem function
chances m
ecosvstem function
wnswfoir) Function
Extreme changes in
structure; wholesale
changes in
extreme alterations
from normal
densities and
organism condition
is often poor;
ecosystem functions
sre severely altered
Virtually all native
ta*a are maintained
with sonie changes
in biomsss and/or
ecosystem functions
are fully maintained
within the range of
nature! variability
Some changes in
structure due to loss
of some rare native
taxa; shifts in
relative abundance
oftaxa but
ubiquitous taxa are
common and
ecosystem functions
arefufly maintained
through redundant
attributes of the
Moderate changes
in structure due to
replacement of
soft® sensitive-
ubiquitous taxa by
more tolerant taxa,
but reproducing
populations of some
sensitive taxa are
maintained; overall
distribution of ail
expected major
groups; ecosystem
functions largely
maintained through
Sensitive taxa are
distribution of major
groups from that
expected; organism
condition shows
signs of
physiological stress;
system function
shows reduced
complexity ami
increased build- up
or export of unused
lived or
endemic taxa
As predicted for
natural occurrence
except for giobai
As predicted for
natural occurrence
except for global
Some may be
marginally present
or absent due to
global extinction or
local extirpation
Some may be
marginally present
or absent due to
global, regional, or
local extirpation
Usually absent
sensitive taxa
As predicted for
natural occurrence,
with at most minor
changes from
natural densities
Most are
maintained with
Some loss, with
replacement by
equivalent sensitive-
ubiquitous texa
May be markedly
Usually absent or
only scarce
sensitive taxa
As. predicted for
natural occurrence,
with at most minor
changes from
natural densities
Present and may be
Common and
abundant; relative
abundance greater
than sensitive-rare,
Present with
maintained; some
replacement by
equivalent taxa of
Frequently absent
or markedly
tolerant taxa
As. predicted for
natural occurrence,
with at most minor
changes from
natural densities
As naturally present
with slight increases
in abundance
Often evident
increases in
Common and often
abundant; relative
abundance may be
sensitive- ubiquitous
Often exhibit
May occur in
extremely high or
extremely low
densities; richness
of ail taxa is low
Tolerant taxa
As naturally occur,
with at most minor
changes from
natural densities
As naturally present
with slight increases
in abundance
Maybe increases in
abundance of
functionally diverse
toierant taxa
May be common
but do not exhibit
Often occur In high
densities and may
be dominant
Usually comprise
the majority of the
assemblage; often
extreme departures
from normal
densities (high or

Implementing the Biological Condition Gradient Framework
Appendix B. The BCG for estuaries and coasts: Frequently Asked Questions
1	- Why bioassessment?
Bioassessment (the use of biological indicators to evaluate environmental condition) allows
biology to be included in management. Living organisms respond to the cumulative impacts of
many anthropogenic stressors, and this can be parsed into the impacts of individual stressors as
well. Bioassessment allows managers to address these impacts through approaches ranging from
public engagement to Clean Water Act regulations. Bioassessment in estuaries integrates many
of the upstream stressors in the larger watershed and is a vital part of managing at the waterbody
and watershed level.
2	- What exactly is the Biological Condition Gradient or BCG?
The BCG is a conceptual scientific framework for interpreting biological response to increasing
effects of stressors on aquatic ecosystems (U.S. EPA 2016). This method was developed by EPA's
Office of Water (Office of Science and Technology) to evaluate the extent of biological impairment
relative to a baseline condition of 'as naturally occurs' or 'minimally disturbed.' The BCG model
defines up to six levels of biological condition along a trajectory of degradation in response to
increasing anthropogenic stress (Figure B-l). The consistent narratives of condition on this
trajectory can be used for comparable interpretation of biological assessment, support of Clean
Water Act objectives, meaningful goal-setting, and coordinated management decision-making
(Davies and Jackson 2006, U.S. EPA 2016).
3	- How does the BCG provide a common language for different biological measures?
The levels of biological condition on the response axis of the BCG serve as a common language
for assessment in comparing different biological measures such as benthic IBIs, seagrass acres,
chlorophyll concentrations, etc. Levels of the BCG have the same inherent definitions for any
biological measure in any setting, so that level 3 carries the same basic meaning e.g. for
phytoplankton in a Vermont stream, benthos in a California lake, and fish communities in a
Georgia estuary.
The descriptive gradient of biological response to stressors (Figure B-l) is the scientific
underpinning behind a coastal and estuarine BCG. The gradient represents the full range of
condition from the natural or undisturbed anchor (level 1) to most severely disturbed (level 6).
Panels of experts bin the gradient into 6 levels using consistent descriptions of each level (left
column of Figure B-l). This process can be applied to any biological setting because the entire
range of biological condition can be defined anywhere and consistently divided into bins (levels).
In practice, U.S. EPA (2016) provides a detailed process for using expert consensus and available
data (e.g., stressor-response relationships from comprehensive monitoring programs) to define
the full range of condition, calibrate the BCG, and consistently assign biological metric scores to
BCG levels. BCG levels 1-6 provide a common language for assessment because the repeatable
scientific process can be applied anywhere that a full range of biological condition can be
described with any method of characterizing biology.

Appendix B
The Biological Condition Gradient:
Biological Response to Increasing Levels of Stress
Levels of Biological Condition
Level 1. Natural structural, functional,
and taxonomic integrity is preserved.
Level 2. Structures function similar
to natural community with some
additional taxa & biomass; ecosystem
level functions are fully maintained.
Level 3. Evident changes in structure
due to loss of some rare native taxa;
shifts in relative abundance; ecosystem
level functions fully maintained.
Level 4. Moderate changes in structure
due to replacement of some sensitive
ubiquitous taxa by more tolerant
taxa; ecosystem functions largely
Level 5. Sensitive taxa markedly
diminished; conspicuously unbalanced
distribution of major taxonomic groups;
ecosystem function shows reduced
complexity & redundancy.
Level 6. Extreme changes in structure
and ecosystem function; wholesale
changes in taxonomic composition;
extreme alterations from normal
Level of Exposure to Stressors
Watershed, habitat, flow regime	Chemistry, habitat, and/or flow
and water chemistry as naturally	regime severely altered from
occurs.	natural conditions.
Figure B-l. Conceptual model of the BCG as used in freshwater. Graphic: U.S. EPA 2016
4 - What are the ecological attributes and how do they relate to the BCG concept?
Attributes are ecological characteristics used to organize biological response. In streams, the
following ten attributes were tested and shown to be useful in environmental management:
Attribute I: Historically documented, sensitive, long-lived or regionally endemic taxa
Attribute II: Sensitive-rare taxa
Attribute III: Sensitive ubiquitous taxa
Attribute IV: Taxa of intermediate tolerance
Attribute V: Tolerant taxa
Attribute VI: Non-native or intentionally introduced taxa
Attribute VII: Organism condition
Attribute VIII: Ecosystem function
Attribute IX: Spatial and temporal extent of stressor effects
Attribute X: Ecosystem connectance

Implementing the Biological Condition Gradient Framework
In estuaries, the Estuarine BCG Workgroup proposes five attributes to be evaluated at multiple
scales, bundling Attributes I through V above into 'Structural and Compositional Complexity':
-	Structural and Compositional Complexity
-	Non-Native Taxa
-	Condition
-	Function
-	Connectance
Identifying and focusing on one, a few, or all attributes simplifies and improves BCG development.
Going beyond the more general definitions of levels in Figure B-l, each attribute provides more
precise definitions of each BCG level, tailored to the specific ecology of that attribute (Table A-l).
5 - What is the estuarine and coastal BCG implementation approach?
BCG implementation is proposed as a set of eleven actions or steps to assist coastal and estuarine
scientists and managers in framing environmental problems and applying BCG methods towards
solving those problems. The steps can be divided into three stages of development.
Steps 1-3. Initial collaborative management for effective BCG outcomes
1.	Define problems, engage partners and stakeholders
2.	Collaborate to define management goals, visions, and objectives
3.	Determine the biological components, stressors, measures, and attributes most relevant to
management objectives
Steps 4-7. A narrative BCG model to identify and communicate condition, develop visions, set goals
and targets, and motivate stakeholders
4.	Delineate and classify the waterbody and watershed of interest
5.	Organize and analyze existing data for the identified measures, collect new data if needed
6.	Define BCG level 1 conditions for the identified attributes
7.	Develop narrative descriptions of the biology expected at each BCG level as a narrative BCG
model; apply to management needs
Steps 8-11. A fully developed BCG model to support both regulatory and non-regulatory needs
8.	Convert narrative descriptions to quantitative metrics and thresholds, calibrate the BCG
9.	Develop a stressor gradient and stressor-response relationships
10.	Organize, interpret, and report results
11.	Develop decision support, communication, and monitoring tools; assist management partners
Taken together, these steps can provide a full path for managing coastal waterbodies. However,
the guidance and the steps are flexible, and managers should use any steps in any order and at
the level of rigor that best meets their management needs.

Appendix B
6	- Why is moving "up" BCG levels and closer to natural conditions a valuable environmental goal?
1.	From an EPA point of view, the Agency's mandate under the Clean Water Act is to "restore
and maintain the chemical, physical, and biological integrity of the Nation's waters", with
integrity often defined in the sense of 'as naturally occurs'.
2.	A natural state, its beauty, and its associated biodiversity confer significant human well-being.
3.	History has shown that deviations from the natural condition can lead to catastrophic
unforeseen consequences (building levees along the Mississippi, introducing rabbits to
Australia, building groins and jetties on beaches, etc.).
4.	A historic benchmark of 'as naturally occurs' can be anchored at a defined point in the past,
which avoids problems associated with 'shifting baselines' where expectations of "good"
condition become lower over time.
5.	For large-scale measures such as the biotope mosaic, natural biological condition describes
the relatively stable environments under which native biota evolved prior to rapid human
population growth. Restoring towards these conditions should favor the survival of valued
native organisms.
7	- How can this complement the ecosystem services/benefits work being done in many estuaries?
This BCG work can easily move forward in tandem with efforts to quantify ecosystem services and
benefits. By assessing the values associated with BCG levels, ecosystem service analyses can
demonstrate the importance and benefits of protecting or restoring an ecological state, and the
costs of not doing so. Ecosystem benefits information helps decision-makers address stakeholder
needs when setting goals and evaluating trade-offs between different management scenarios.
8	- What is the biotope mosaic method for bioassessment?
This bioassessment approach quantifies estuary-wide changes to living habitats (biotopes) and to
mosaics of these biotopes over time. Scientists at the Tampa Bay Estuary program (TBEP) posited
that the cumulative impacts of stressors manifest through destruction and conversion of
biotopes, and that returning the proportions or balance of biotopes to a previous and less-
disturbed state would benefit the estuary as a whole by moving the estuary closer to the mosaic
of biotopes under which native organisms evolved. Several quantitative metrics can be applied
to evaluate the estuary-wide mosaic of biotopes. Tampa Bay stakeholders and the public valued
quantity and diversity of habitats, and this method proved effective at communicating estuarine
condition and developing stakeholder visions and goals that led to management actions and
environmental results. This approach was written into a paper (Cicchetti and Greening 2011) that
informs scientists and managers of a successful management program that has many parallels
to the coastal/estuarine BCG framework.
9	- How is biotope defined?
A biotope is an area that is relatively uniform in physical structure, and that can be identified by
the dominant biota (Davies et al. 2004). A biotope is defined through the repeatable combination
of an abiotic habitat and a strongly associated biological species or group, and the biotope is
named after that species or group. Biotope can be used interchangeably with hobitot when
habitats specifically include biology: a sand bar is a habitat but not a biotope while seagrass is
both a habitat and a biotope. A more informative biotope name would include both the taxon

Implementing the Biological Condition Gradient Framework
and the abiotic setting, e.g., 'Zostero marina on subtidal sandy mud'. Bioassessment includes
biotopes, but not physical habitats. However, the term 'habitat' is more familiar to a public
audience and may be used in that context for better communication to stakeholders: 'the habitat
mosaic'. Biological classifications in the Coastal and Marine Ecological Classification Standard
(CMECS) document (www.csc.noaa.gov/cmecs) have a strong focus on the biotope concept, and
CMECS is a federally approved national classification standard.
10 - Where have BCG or similar approaches been applied to estuaries and coasts?
BCG approaches have been applied in Narragansett Bay, Mobile Bay, Lower Columbia River,
Puerto Rico Coral Reefs, and Tampa Bay (essentially a BCG approach). Work in these estuaries
is described in Section 6 of the EPA document "Implementing the Biological Condition Gradient
Framework for Management of Estuaries and Coasts".
Other estuaries have been evaluated and managed with bioassessments and other methods
using elements in common with the BCG approach. Two examples are described below:
Example 1:
Buzzards Bay (MA) and its side estuaries have suffered from losses and alterations to natural
species, communities, and habitats. The Buzzards Bay Coalition compared biological data to a
historical baseline, in this case pre-colonial conditions. While Buzzards Bay has not developed
a BCG, many of the critical elements exist - use of biology for assessment, determination of
conditions 'as historically occurred', and use of expert consensus and best professional judgement
to evaluate data (Figure B-2).

Appendix B
If you want to track the spread of nitrogen pollution in
your own corner of Buzzards Bay, watch the eelgrass.
This rooted underwater plant grows in meadows along
the bottom of harbors, coves, and tidal rivers that have
clear, shallow waters.
But when nitrogen pollution increases, it fuels the
growth of algae that reduces water clarity. Without
enough sunlight reaching the bottom, eelgrass dies. And
those species that depend on eelgrass - young fish, blue
crabs, and bay scallops - begin to vanish, too.
In 2015, the eelgrass score did not change from its
2011 score of 23. This score is based on the extent
of eelgrass meadows in the Bay in 2015 compared
with the Bay's maximum historical potential eelgrass
coverage (estimated by the Buzzards Bay National
Estuary Program).
Along with inputs of nitrogen pollution, eelgrass losses
in Buzzards Bay have leveled off as a whole. The good
news is that when we reduce nitrogen pollution and
water clarity improves, eelgrass can recover on its own.
For instance, in the Wareham River and outer New
Bedford Harbor, recent wastewater and stormwater
upgrades have led to increases in eelgrass acreage.
Bay Scallops 2 ^ Down I from 2011
Bay scallops were to Buzzards Bay what oysters
historically were to Long Island and the Chesapeake Bay.
But today, our once-abundant and highly-valuable bay
scallops have all but disappeared from most parts of
Buzzards Bay.
The bay scallop score fell to 2 in 2015, down one
point from 2011. The Massachusetts Division of Marine
Fisheries reported an average catch of roughly 1,500
bushels per year between 2011-2015. It's a stunning
decline from 1985, when nearly 70,000 bushels of bay
scallops were harvested in Buzzards Bay.
This drop in bay scallop harvest is linked to the effects
of nitrogen pollution. Bay scallops live and grow among
the shelter of eelgrass; as these underwater meadows
have disappeared, so have bay scallops. The graph below
shows the relationship between these two independent,
but closely related, indicators. As we reduce nitrogen
pollution and restore clean water, the Bay's signature
shellfish can begin to return to health.
45 Years of Eelgrass and Bay Scallop Abundance in Buzzards Bay (1970-2015)
Figure B-2. Excerpt from Buzzards Bay Report Card output. Trends of various measures are shown,
as well as resource improvements or declines. Numbers represent the comparative value of the resource
relative to historic reference value-a BCG concept. Graphic: Buzzards Bay Coalition 2015
Example 2:
The Chesapeake Bay Program is a well-funded effort that has monitored biological condition
for decades in several states. Many of their restoration targets are based on historic baselines
(CBP 2000). A variety of biological endpoints are monitored on a routine basis, and biological
condition is assessed by summarizing the data into indices based on information from reference
sites. These indices are reported separately, for the entire Bay and for each sub-embayment,
and can be compared to previous monitoring data for examination of trends. These indicators
are also combined into an overall Bay Health Index (Figure B-3).
¦ Eelgrass coverage
B Bay scallops catch

Implementingthe Biological Condition Gradient Framework
2012 Chesapeake Bay
Report Card
Bay Health Index
The Bay Health Index is an average of all seven indicators (chlorophyll a,
dissolved oxygen, water clarity, total nitrogen, total phosphorus, aquatic
grasses, and Benthic IBI) into an overall assessment of Chesapeake Bay
Bay Health
Moderate ecosystem health. The overall health of the Bay improved this
year, from 38% in 2011 to 47% in 2012. See trends tab for comparison.
Every Indicator except aquatic grasses improved in 2012. Total nitrogen
seems to be improving over time, while aquatic grasses have been
declining for several years now.
Figure B-3. 2012 Chesapeake Bay Report Card output. Graphic: CBP 2000
Although work in the Chesapeake was not done for BCG development, many of the important
elements of BCG are included. Biological data are used for assessment; reference conditions
are defined; multiple levels of condition are identified (in some cases only good/fair/poor);
and multiple assemblages are evaluated alone and in concert, at multiple scales, to determine
estuary health.
While these programs successfully used BCG concepts to manage estuaries, the development
of an actual BCG would allow unification of the indices used into a common language, better
management of CWA goals related to "as naturally occurs", comparability to sub-estuaries
and to other estuaries, more consistent prioritization, management, and monitoring, and
a more effective way to communicate condition to the public and other stakeholders in
a meaningful way.
11 - How have NEPs most benefited from the estuarine and coastal BCG?
NEPsthat are using a BCG approach identify significant benefits in 1) setting meaningful targets
for habitat protection and restoration and 2) engaging and motivating the public and other
stakeholders to participate in waterbody management and to improve the environment
by changing behaviors and actions.

Appendix C
Appendix C Attendees at the 2008 workshop: A proposed organizing
framework for bioassessment of estuaries
The goal of this effort was to develop and refine an integrative framework to provide a common
language and enable meaningful comparisons among measures and waterbodies, thus allowing
better management of entire estuaries and watersheds.
Walter Berry1
Curtis Bohlen2
Claire Buchanan3
Lilian Busse4
Marty Chintala1
Giancarlo Cicchetti1
Bob Connell5
Susan Davies6
Chris Deacutis7
Naomi Detenbeck1
Ed Dettmann1
Jerry Diamond8
Walt Galloway1
Tim Gleason1
Diane Gould9
Holly Greening10
Susan Jackson11
Danielle Kreeger12
Chris Madden13
Tim O'Higgins14
Angela Padeletti12
Peg Pelletier1
Margherita Pryor9
Richard Ribb7
Ed Sherwood10
Hilary Snook15
Martha Sutula16
1	U.S. EPA, Atlantic Ecology Division, Narragansett, Rl
2	Casco Bay Estuary Partnership, Portland, ME
3	Interstate Commission on the Potomac River Basin, Rockville, MD
4	San Diego Water Board, San Diego, CA
5	New Jersey Department of Environmental Protection, Leeds Point, NJ
6	Maine Department of Environmental Protection, Augusta, ME
7	Narragansett Bay Estuary Program, Narragansett, Rl
8Tetra Tech Corporation, Owings Mills, MD
9 U.S. EPA, Region 1, Boston, MA
10Tampa Bay Estuary Program, St. Petersburg, FL
11	U.S. EPA, Office of Water, Washington, DC
12	Partnership for the Delaware Estuary, Wilmington, DE
13	South Florida Water Management District, West Palm Beach, FL
14	U.S. EPA, Western Ecology Division, Newport, OR
15	U.S. EPA, Region 1, North Chelmsford, MA
16	Southern California Coastal Water Research Project, Costa Mesa, CA

Implementing the Biological Condition Gradient Framework
Appendix D. Attendees at the 2009 workshop: A biological condition
gradient for Narragansett Bay
The goals of this workshop were to develop a concept and qualitative description of 'minimally
disturbed' in the Narragansett Bay estuarine system, identify key indicators, and identify the existing
historical and current data that are available for these key indicators.
1	Brown University, Providence, Rl
2	Narragansett Bay Estuary Program, Narragansett, Rl
3	U.S. EPA, Atlantic Ecology Division, Narragansett, Rl
4	University of Rhode Island, Graduate School of Oceanography, Narragansett, Rl
5	University of Rhode Island, Coastal Institute, Narragansett, Rl
6	Save the Bay, Providence, Rl
7	Maine Department of Environmental Protection, Augusta, ME
8Tetra Tech Corporation, Owings Mills, MD
9	Rhode Island Natural History Survey, Kingston, Rl
10	College of William and Mary, Virginia Institute of Marine Science, Gloucester Point, VA
11	U.S. EPA, Office of Water, Washington, DC
12	University of Rhode Island, Kingston, Rl
13	Rhode Island Department of Environmental Management, Providence, Rl
14	Massachusetts Bays Program, Boston, MA
15	NOAA, National Marine Fisheries Service, Narragansett, Rl
16	Rhode Island Department of Environmental Management, Providence, Rl (retired)
17	U.S. EPA, Region 1, Boston, MA
18	University of Massachusetts, Water Resources Research Center, Amherst, MA
19	Marine Ecology and Technology Applications, Inc., Waquoit, MA
20	U.S. EPA, Region 1, North Chelmsford, MA
21	NOAA, National Marine Fisheries Service, Gloucester, MA
Andrew Altieri1
Tom Ardito2
Walter Berry3
David Borkman4
Keryn Bromberg Gedan1
Carrie Byron5
Christopher Calabretta4
Rachel Calabro6
Dan Campbell3
Marty Chintala3
Giancarlo Cicchetti3
Earl Davey3
Susan Davies7
Chris Deacutis2
Ed Dettmann3
Walt Galloway3
Jonathan Garber3
Jeroen Gerritsen8
Susan Jackson11
David Gregg9
Alana Hanson3
Carl Hershner10
Susan Jackson11
Roxanne Johnson3
Q Kellogg12
Sue Kiernan13
Chris Krahforst14
Lesley Lambert2
Chris Melrose15
Dave Murray1
Candace Oviatt4
Peg Pelletier3
Carol Pesch3
Chris Powell16
Sheldon Pratt4
Warren Prell1
Margherita Pryor17
Paul Rees18
Richard Ribb2
Ken Rocha3
Rodney Roundtree19
Liz Scott13
Emily Shumchenia4
Ted Smayda4
Charlie Strobel3
Diane Switzer20
Glen Thursby3
Sue Tuxbury21
Cathy Wigand3

United States
Environmental Protection
Office of Research and Development
National Health and Environmental
Effects Research Laboratory
Atlantic Ecology Division
Narragansett, Rl 02882
Official Business
Penalty for Private use
EPA/600/R-15/287 | May 2017

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