NATIONAL ESTUARINE EUTROPHICATION 

ASSESSMENT UPDATE: 

Workshop Summary and Recommendations for Development of a 

Long-term Monitoring and Assessment Program

Proceedings of a workshop September 4-5, 2002

Patuxent National Wildlife Research Refuge, Laurel, Maryland

U.S. Department of Commerce

National Oceanic and Atmospheric Administration

National Ocean Service

National Centers for Coastal Ocean Science
This report should be cited as: S. Bricker, G. Matlock, J. Snider, A. Mason, M. Alber, W. Boynton, D. Brock, G. Brush, D. 

Chestnut, U. Claussen, W. Dennison, E. Dettmann, D. Dunn, J. Ferreira, D. Flemer, P. Fong, J. Fourqurean, J. Hameedi, 

D. Hernandez, D. Hoover, D. Johnston, S. Jones, K. Kamer, R. Kelty, D. Keeley, R. Langan, J. Latimer, D. Lipton, R. 

Magnien, T. Malone, G. Morrison, J. Newton, J. Pennock, N. Rabalais, D. Scheurer, J. Sharp, D. Smith, S. Smith, P. Tester, 

R. Thom, D. Trueblood, R. Van Dolah. 2003. National Estuarine Eutrophication Assessment Update: Workshop summary 

and recommendations for development of a long-term monitoring and assessment program. Proceedings of a workshop 

September 4-5, 2002, Patuxent Wildlife Research Refuge, Laurel, Maryland. NOAA, National Ocean Service, National 

Centers for Coastal Ocean Science. Silver Spring, MD: 19 pp.

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National Estuarine Eutrophication Assessment Update:

Workshop Summary and Recommendations for Development of a Long-term 

Monitoring and Assessment Program

Proceedings of a Workshop September 4-5, 2002

Patuxent National Wildlife Research Refuge, Laurel, Maryland

April 2004

National Centers for Coastal Ocean Science

National Ocean Service

National Oceanic and Atmospheric Administration

1305 East-West Highway

Silver Spring, MD 20910
PARTICIPANTS

Workshop Sponsors and NOAA Project Team:

Suzanne Bricker, Gary Matlock, Jean Snider and Andrew Mason

Workshop Participants

Merryl Alber University of Georgia

Walter Boynton University of Maryland

David Brock Texas Water Development Board

Grace Brush Johns Hopkins University

David Chestnut South Carolina Department of Health and Environmental Control

Ulrich Claussen German Federal Environmental Agency

Bill Dennison University of Maryland

Edward Dettman Environmental Protection Agency, Narragansett

Dean Dunn National Oceanic and Atmospheric Administration

Joao Ferreira Institute of Marine Research, Universidade Nova de Lisboa, Portugal

David Flemer Environmental Protection Agency, Washington, DC

Peggy Fong University of California, Los Angeles

James Fourqurean Florida International University

Jawed Hameedi National Oceanic and Atmospheric Administration 

Debra Hernandez South Carolina Department of Health and Environmental Control

Daniel Hoover University of Hawaii

Deborah Johnston California Department of Fish and Game

Stephen Jones University of New Hampshire

Krista Kamer Southern California Coastal Water Resource Program

Ruth Kelty National Oceanic and Atmospheric Administration

David Keeley Maine State Planning Offi ce

Richard Langan Cooperative Institute for Coastal Estuarine and Environmental Technology

Jim Latimer Environmental Protection Agency, Narragansett

Doug Lipton University of Maryland

Robert Magnien Maryland Department of Natural Resources

Thomas Malone University of Maryland

Gerold Morrison Environmental Protection Agency Hillsborough County

Jan Newton Washington State Department of Ecology

Jonathan Pennock University of New Hampshire

Nancy Rabalais Louisiana Universities Marine Consortium

David Scheurer National Oceanic and Atmospheric Administration

Jonathan Sharp University of Delaware

Dick Smith US Geological Survey

Stephen Smith Centro de Investigacion Cientifi ca y de Educacion Superior de Ensenada

Patricia Tester National Oceanic and Atmospheric Administration

Ron Thom Battelle Marine Sciences Laboratory

Dwight Trueblood Cooperative Institute for Coastal Estuarine and Environmental Technology 

Robert Van Dolah South Carolina Department of Natural Resources
TABLE OF CONTENTS

Executive Summary: This document describes results and recommendations of 

the National Estuarine Eutrophication Assessment (NEEA) Update Workshop held 

by NOAA at the Patuxent National Wildlife Research Refuge in Laurel, Maryland on 

September 4 –5, 2002.

INTRODUCTION: THE PROBLEM............................................................................4

THE WORKSHOP......................................................................................................6

 Objectives............................................................................................................6 

Desired Outcomes...............................................................................................6

OVERALL RECOMMENDATIONS.............................................................................8

TOPICS OF DISCUSSION.......................................................................................10

 Defi nition of Eutrophication...............................................................................10

Typology Development......................................................................................10

 Monitoring, Assessment and Classifi cation.......................................................12 

 Nutrient related eutrophication......................................................................12

 Socioeconomic impacts to human uses........................................................14

 Modeling and Management of Eutrophication...................................................15

NEXT STEPS...........................................................................................................17

REFERENCES.........................................................................................................18

1

During recent decades, human activities have increased 

nutrient loads to estuaries and coastal waters many times 

above natural levels. These changes have caused a variety 

of impacts. Potential consequences of eutrophication range 

from ecological changes to socioeconomic impairments 

(e.g. fi sheries) to serious human health threats. There 

is clearly a need to monitor and assess causes and 

consequences of nutrient related water quality conditions 

to provide the basis for effective management of this 

pervasive problem.

Workshop Intent and Objectives

The overall intent of the workshop was to discuss the 

design of a long-term monitoring and assessment program 

to address nutrient over-enrichment and consequent water 

quality problems in estuaries and coastal waters (Figures 

1 and 2). This follow up program should address the 

question “To what extent do nutrient inputs to US estuaries 

and coastal waters impair society’s uses of those water 

bodies?” by measurement and assessment of:

• Status and trends of water quality related to 

nutrient enrichment.

• Causes of observed problems (e.g. susceptibility, 

nutrient loadings). 

• Socioeconomic impacts of nutrient related water 

quality degradation.

• Alternative management responses and the 

impacts of those alternatives.

Desired Outcomes

The framework developed at the workshop served as 

the basis for this guidance document which describes 

the development and implementation of the program 

including:

• Classifi cation of types of estuaries and coastal 

water bodies.

• Appropriate variables for characterization of 

nutrient over-enrichment status.

• Assessment methods for determination of 

nutrient pollution status and trends, human use 

impairment, economic impacts, and causes of 

observed problems (e.g. loadings, susceptibility).

• Methods for translation and transfer of data/

information from scientists to managers.

• Identifi cation/development of a database or data 

access framework.

• Identifi cation of long-term data sources.

• Identifi cation of potential partnerships to support 

this long-term effort.

Discussion Topics

Workshop discussions, mostly in parallel breakout groups, 

were designed to address:

• Defi nition of Eutrophication

Workshop participants fi ne tuned a defi nition and 

proposed an operational defi nition to be adopted 

for the program under development (see page 

10).

• Typology Development

Workshop participants identifi ed a list of variables 

(hydromorphological and physico-chemical 

parameters) for consideration in the development 

of a type classifi cation specifi cally to help in the 

assessment of eutrophic conditions. The main 

purpose for determining typology is that the 

thresholds for eutrophication classes will vary 

according to type.

Figure 1. Conceptual model of eutrophication.

EXECUTIVE SUMMARY
2

Figure 2. Nutrient sources and effects in estuaries (Bricker et al., 1999).
3

• Monitoring, Assessment and 

 Classifi cation

Workshop participants discussed two monitoring 

assessment and classifi cation topics:

Nutrient related eutrophication

A core set of variables that should be measured 

in all types of water bodies and an enhanced set 

of variables, to be used only if applicable, were 

developed by workshop participants. This includes 

measurement of loadings so causal linkages can 

be made between loading and water quality status. 

Assessment methods should be developed with 

these variables. Participants agreed to use NEEA 

methods and recent adaptations as a starting 

point for development of improved assessment 

methods. 

Socioeconomic impacts to human uses 

This component of the assessment was not 

included in the NEEA and requires further 

development. It was agreed that participation of 

additional social scientists and economists would 

be crucial in developing an appropriate approach 

to socioeconomic analysis.

• Modeling and Management of 

 Eutrophication

Models need to be developed to better understand 

and predict nutrient input/water body response 

relationships to guide management of human 

related eutrophication.

Participants concluded that a proper adaptive 

management strategy for eutrophication must, 

besides having effective abatement measures, 

address two general themes:

1. translation and integration of science into 

information and tools that are useful to 

managers, and 

2. reporting of results to the public and 

Congress to leverage action and funding for 

management and related research. 

These discussions led to a recommendation that working 

groups be formed to address three categories of issues 

more thoroughly (see recommendations chapter for more 

detail): 

1. Typology.

2. Monitoring, Assessment and Classifi cation 

including variable selection and development 

of metrics and indices for nutrient related 

conditions and associated economic impacts.

3. Modeling and Management for better understanding of loading/response relationships, 

and to address what mangers need to 

successfully manage nutrient related issues 

in estuaries and coastal waters. 

Next Steps

The development of a monitoring and assessment 

program for eutrophication assessment will include further 

development of typology, defi nition of relevant indicator 

variables (including reference conditions and classifi cation), 

modeling, and management. The overall guidance for 

periodic assessments should include a component that 

assesses the socioeconomic impacts of eutrophication. 

Further development of these methods and models should 

be done through an appropriate selection of candidate 

estuaries for pilot studies.
4

The Problem

Eutrophication is a natural process in which the addition 

of nutrients to estuaries and coastal waters from the 

watershed, atmosphere, and ocean stimulates algal 

growth. During recent decades, human activities such as 

fossil fuel burning and agricultural use of fertilizers have 

increased nutrient loads to many times natural levels. 

These changes have caused a variety of impacts; high 

levels of chlorophyll a (Boynton et al., 1982), overgrowth 

of seaweed and epiphytes, occurrences of anoxia and 

hypoxia (Gerlach, 1990; CENR, 2000), nuisance and toxic 

algal blooms (ORCA, 1992, Rabalais et al., 1996), and 

loss of submerged aquatic vegetation (SAV, Twilley et al., 

1985, Burkholder et al., 1992b; Figures 1 and 2). 

Potential consequences of eutrophication range from mere 

nuisances to serious human health threats. Anoxia related 

fi sh kills (Glasgow and Burkholder, 2000) cause noxious 

odors. Loss of seagrasses (Twilley et al., 1995; Burkholder 

et al., 1992b, Figure 3) and benthic organisms (Rabalais 

and Harper, 1992) may lead to long-term reductions 

in abundance, diversity, and harvest of fi sh in eutrophic 

systems (Brietburg, 2002). Algal toxins threaten human 

health if ingested in fi sh or shellfi sh tissue or when inhaled 

directly (Anderson et al., 2000). These impacts have been 

observed at varying levels in water bodies of the U.S. and 

many other countries (Table 1).

Measurable socioeconomic costs include economic losses 

to fi sheries (Lipton and Hicks, 1999, 2003; Lipton, 2003; 

Mistaien et al., 2003), seasonal tourism, and the seafood 

industry (Anderson et al., 2000), while indirect and nonuse values are more diffi cult to determine (Turner et al., 

1999). Of particular concern, and a challenge to future 

management, are predicted increases in problems as 

coastal populations and use of fertilizers and fossil fuels 

continue to increase (Bricker et al., 1999; NRC, 2000; 

Boesch, 2002). There is clearly a need to monitor and 

assess causes and consequences of nutrient related 

eutrophic conditions to provide the basis for effective 

management of this pervasive problem.

This document describes the results of the National 

Estuarine Eutrophication Update Workshop held by NOAA 

at the Patuxent National Wildlife Research Refuge in 

Laurel, Maryland on September 4 –5, 2002. The purpose 

of the workshop was to discuss the design of a long-term 

monitoring and assessment program to address nutrient 

over-enrichment and consequent water quality problems in 

estuaries and coastal waters using the National Estuarine 

Eutrophication Assessment and recent methodological 

Table 1. Example locations of Observed Eutrophic Symptoms.

Eutrophication 

Symptoms

System or Country 

of Observation

Toxic Algal Blooms

•Pamlico and Neuse River Estuaries 

(Burkholder et al., 1992a, 1995, 1999)

•NE Coast of UK (Joint et al., 1997)

Nuisance Algal Blooms

•Lower Laguna Madre 

(Whitledge and Pulich, 1991)

•Southern North Sea (Gillbricht, 1988)

•Baltic Sea (Bonsdorff et al., 1997)

•Mediterranean Sea (e.g. Lac de Tunis: 

Kelly and Naguib, 1984), 

•Northern Adriatic 

(Chiaudani et al., 1980), 

•Australia (Hodgkin and Birch 1982; 

Hodgkin and Hamilton 1993) 

•Japan (Okaichi, 1989; Okaichi, 1997)

Depleted Dissolved Oxygen

•Mississippi River Plume 

(Rabalais et al., 1996)

•Chesapeake Bay 

(Cooper and Brush, 1991)

Loss of SAV

•Chesapeake Bay 

(Orth and Moore, 1983, 1984)

•Tampa Bay (Greening et al., 1997)

•Laguna Madre (Onuf, 1995)

Figure 3. SAV with colonizing algae (inset) and without.

INTRODUCTION
5

improvements (NEEA; Bricker et al., 1999, Bricker et al., 

2003.) as a starting point. 

The follow up program should be designed to address the 

question “To what extent do nutrient inputs to US estuaries 

and coastal waters impair society’s uses of those water 

bodies?” It should also address management of human 

related eutrophication in areas that are impacted. This 

program should include measurement, assessment, and 

modeling of water quality related to nutrient enrichment, 

the impacts of nutrient related water quality degradation on 

human uses of estuaries, the sources of nutrients to water 

bodies and factors that infl uence development of nutrient 

related problems, and the development of appropriate 

management responses. There were 40+ participants, 

resource managers and scientists, from federal and state 

agencies, and universities who were specifi cally chosen 

for their experience, knowledge, and geographic location 

(see participant list, inside front cover).
6

After introductory remarks by Dr. Gary Matlock, Director of 

the National Centers for Coastal Ocean Science (NCCOS), 

three speakers made presentations entitled:

1. “What data and information do managers need in 

order to address coastal nutrient pollution and overenrichment?” (David Keeley, Maine State Planning 

Offi ce).

2. “Application of the National Estuarine Eutrophication 

Assessment (NEAA) to some European estuaries.” 

This presentation demonstrated the use of statistically 

determined quantitative values calculated from data, 

GIS for calculating area weighted scores rather than 

expert knowledge, and a simple hydrological and 

exchange model to determine anthropogenic pressure 

and assimilation capacity of the systems.” (Joao 

G. Ferreira, Institute of Marine Research, Portugal; 

Bricker et al., 2003).

3. “Measuring the economic impacts of eutrophication”. 

This presentation showed the economic impacts of 

nutrient-enrichment in Chesapeake Bay using the 

Striped Bass recreational and Blue Crab commercial 

fi sheries as examples. (Doug Lipton, Department of 

Agricultural and Resource Economics and Sea Grant 

Extension, University of Maryland; Lipton and Hicks, 

1993, 2003; Lipton, 2003; Mistaien et al., 2003).

The participants worked in breakout groups for the 

remainder of the two day workshop, discussing the 

objectives of the program being designed and making 

recommendations on how to proceed.

Objectives

The focus of the workshop was to develop a monitoring 

and assessment program, including plans for periodic 

assessment updates that would be the basis for evaluation 

of trends in nutrient related water quality issues, with 

important implications to the management of estuarine 

and coastal resources. The update components include: 

assessment of status and trends in nutrient related water 

quality, causes of observed problems (i.e., nutrient inputs, 

physical processing), consequences to water quality 

and to human uses of estuaries and coastal waters (if 

nothing is done), and alternative management options 

and the impacts of those alternatives. Consequently, three 

breakout groups, working mostly in parallel, addressed the 

following issues:

• The defi nition of “cultural eutrophication” or 

“human-induced nutrient over-enrichment” 

including what variables “defi ne” eutrophication 

and what are the thresholds that characterize an 

estuary/coastal water as eutrophic.

• Classifi cation of estuaries/coastal waters by 

physical/chemical characteristics into groups 

that behave similarly such that models of nutrient 

input/water body response might be determined 

(i.e., development of an appropriate typology). 

• The data and information, most useful format, 

and the temporal and spatial scales of data and 

information that are needed by managers to do 

their jobs effi ciently and successfully, and how 

scientists can better provide what managers 

need. 

• Appropriate variables, variable characteristics, 

and methods to accurately characterize nutrient 

over-enrichment including core and enhanced 

sets of variables, and temporal and spatial scales 

for sampling.

• Assessment methods and models for linking 

nutrient related water quality degradation with 

impacts to society’s uses of estuaries/coastal 

waters including cost benefi t analyses.

Desired Outcomes

The principal desired outcome was the development of 

a framework for a long-term monitoring and assessment 

program to address the question of whether, and to what 

extent, nutrient inputs are causing impairments to society’s 

uses of estuaries. The framework developed at the 

workshop served as the basis for this guidance document 

describing the development and implementation of the 

program including:

• Appropriate variables for characterization of nutrient 

over-enrichment status.

THE WORKSHOP
7

• Assessment methods for determination of nutrient 

pollution status, susceptibility to nutrient overenrichment, human use impairment, trends in 

nutrient pollution status, and economic impacts of 

nutrient related water quality problems.

• Models for understanding nutrient input/water 

body response that can be used in predictive and 

management capacities.

• Methods for measurement of sources and amounts 

of nutrient loading to explain nutrient pollution 

status and trend data.

• Methods for timely delivery and appropriate 

formatting of data and information from scientists to 

managers.

• Identifi cation/development of a database or data 

access framework.

• Identifi cation of long-term data sources.

• Identifi cation of potential partnerships to support 

this long-term effort.
8

Development of regional nitrogen input limits for 

estuarine and Great Lakes coastal systems). 

4. Convene sub-groups to tackle details of :

• Typology classifi cation that captures system 

variability in a context that is useful for the 

assessment and management of eutrophication.

• Monitoring, Assessment and Classifi cation 

including selection of variables and assessment 

methods appropriate for describing: 1) nutrient 

related eutrophication, and 2) consequences 

of impacts, such as the relationships between 

society’s uses and nutrient related impacts on 

estuarine/coastal waters.

• Modeling and Management of eutrophication 

for better understanding of nutrient input/water 

body response and other relationships that 

elucidate causes of, and management solutions 

to, eutrophication which should include a clearer 

defi nition of manager’s needs (information and 

tools) and impacts of alternative management 

actions, including if no action is taken. 

5. Develop the impact component (i.e. human use 

impairment) of the assessment, particularly the link 

between nutrient related water quality degradation 

and society’s uses of estuaries and coastal waters. 

Participants agreed that additional economists and 

social scientists should be brought into the group to 

provide the experience and knowledge needed to 

develop the approach and methods for the envisioned 

national scale evaluation of the link between nutrient 

pollution and economic costs. 

6. Issues should be addressed on three levels as for 

the NEEA (Bricker et al., 1999; NOAA 1996, 1997a, 

b, c, 1998): individual estuary, regional, and national. 

Program results should maintain local relevance 

and must provide data and information to resource 

managers in a timely way and in a useful format. 

7. Develop tools for use by resource managers, such as 

models of the link between nutrient loading and fi sh 

production, and between nutrient loading and loss of 

submerged aquatic vegetation.

While most of these topics were touched on during the 

two days of discussion, there was inadequate time for full 

consideration of all program components. What follows 

are summaries of each of the discussions by topic, and 

recommendations for how to proceed, based on the group’s 

discussions.

1. Develop a quantitative monitoring and assessment 

program to provide the basis to address nutrient 

related eutrophication in US estuaries, embayments, 

and other coastal waters (including Great Lakes as 

well as Alaskan and Hawaiian systems). This program 

should be viewed as interactive with, and a companion 

program to, the National Research Program for 

Nutrient Pollution in Coastal Waters (Howarth et al., 

2003). 

2. Program development should proceed on two 

simultaneous and related tracks: 

• Typology (classifi cation) which will lead to variable 

selection for assessment of nutrient related 

eutrophication, appropriate spatial and temporal 

sampling scales, appropriate assessment 

methods, development of nutrient input/water body 

response relationships, and predictive models for 

different input scenarios for the different water 

body types, and

• Identifi cation of linkages and relationships 

between: nutrient-impaired water quality, their 

impacts on estuarine and coastal resources, and 

consequent impacts on society’s uses of estuarine 

and coastal resources.

3. Partnerships should be identifi ed and developed 

to assure long-term funding and should use prior 

experiences of other programs to develop broad scale 

consistency. For instance, the EPA Offi ce of Water’s 

development and implementation of nutrient criteria 

and total maximum daily loads (TMDLs; http://www.

epa.gov/owow/tmdl/) may benefi t from a program such 

as this and vice versa. A product of those partnerships 

could be an overall national approach to assess and 

manage eutrophication that combines assessment 

approaches (e.g. NEEA update) and management 

aspects (e.g. US EPA Atlantic Ecology Division [AED] 

OVERALL RECOMMENDATIONS
9

8. Conduct a pilot study to further develop and test 

assessment methods developed by sub-groups in a 

variety of systems representing the diversity of types 

of estuaries along the US coast. Candidate estuaries 

must have an existing robust database.

9. Learn from work done to implement the European 

Union Water Framework Directive (WFD 2000/60/

EC, e.g. COAST, 2003; Bettencourt et al., in press.; 

Ferreira et al., 2003) and the Oslo-Paris Convention 

for Protection of the Marine Environment of the NorthEast Atlantic (OSPAR, 2002). In these fora much work 

has already been done regarding typology, reference 

conditions and threshold determination, as well as 

classifi cation of eutrophication status using statistically 

determined quantitative values calculated from data, 

GIS for calculating area weighted scores, and simple 

hydrological and exchange models to determine 

anthropogenic pressure and assimilation capacity of 

the systems.

10. Improve public outreach concerning causes and 

consequences of nutrient over-enrichment to develop 

public support for management through: identifi cation of 

the problem, development of solutions, implementation 

of solutions, and outcomes or status of implementation 

on estuarine and coastal resources.
10

Defi nition of Eutrophication 

Workshop participants agreed that there were several 

existing defi nitions of eutrophication that would be 

adequate, with some revisions. The defi nition on page v in 

the Executive Summary of the NEEA (below, Bricker et al., 

1999) was used a starting point and the defi nition refi ned 

based on some additional considerations (see box). 

Eutrophication is the accelerated production of organic 

matter, particularly algae, in a water body. It is usually 

caused by an increase in the amount of nutrients being 

discharged to the water body. As a result of accelerated 

algal production, a variety of impacts may occur, including 

nuisance and toxic algal blooms, depleted dissolved 

oxygen, and loss of submerged aquatic vegetation. These 

impacts are interrelated and usually viewed as having a 

negative effect on water quality and ecosystem health.

Some additional considerations for enhancing the 

defi nition follow: 

• Need to focus on the anthropogenic side (i.e. “cultural” 

eutrophication), 

• Couple susceptibility/sensitivity with the level of 

enrichment, 

• Should call eutrophication “nutrient enrichment”, 

“nutrient over-enrichment”, or “nutrient pollution”, 

• Should use climatology in determination of cultural 

eutrophication in the context of departure from longterm average conditions, 

• Add Nixon’s defi nition (i.e., eutrophication is the 

accumulation of organic matter from anthropogenic 

inputs, or as an increase in organic matter in the water 

column),

• Include the undesirable effects of nutrient over 

enrichment and add quantitative measures, 

• Defi nition should include a section on the meaning of 

the word for management purposes,

• Defi nition should include nutrient forcing and 

management goals.

The following defi nition incorporates recommended 

revisions and should be adopted for the program under 

development:

Eutrophication is a natural process by which productivity 

of a water body, as measured by organic matter, increases 

as a result of increasing nutrient inputs. These inputs 

are a result of natural processes but in recent decades 

they have been greatly supplemented by various human 

related activities. Cultural eutrophication, or nutrient overenrichment, is the enhanced accumulation of organic 

matter, particularly algae, that is caused by human related 

increases in the amount and composition of nutrients 

being discharged to the water body. A variety of impacts 

may result, including nuisance and toxic algal blooms, 

depleted dissolved oxygen, and loss of submerged 

aquatic vegetation and benthic fauna. These impacts 

are interrelated and usually viewed as having a negative 

effect on water quality, ecosystem health, and human 

uses. Management concerns should address the human, 

or cultural, portion of nutrient additions insofar as the 

additions are detrimental to the environment.

Typology Development

Development of a type-classifi cation for estuaries and 

coastal waterbodies is the cornerstone to the development 

of the assessment and monitoring program because the 

waterbody type will dictate the appropriate variables 

to monitor, the sampling time frame and spatial scale, 

and appropriate management actions. The classifi cation 

scheme should capture the system variability in a context 

that is useful for the assessment of eutrophication and 

should be quantitative in nature (Figure 4).

A list of hydromorphological and physico-chemical variables 

(below) was identifi ed for consideration in the development 

of types of characteristic estuarine and coastal waters 

(including the Great Lakes). While the quality of the receiving 

water body (i.e. unimpacted levels of; nutrients, Chl a, etc) 

is not included here, it might be considered since these 

conditions clearly separate systems such as Florida and 

Hawaii from others with naturally higher level nutrients and 

Chl a. Additionally, coastal waters should be considered 

along with estuaries in order to include descriptions of 

the diversity of water body types that were included in the 

NEEA as some are not traditional estuaries. 

TOPICS OF DISCUSSION
11

The philosophy for development of the list of variables was 

to review the obvious types within regions to ensure that all 

major types would be described, and then look for variables 

that might be used to develop an objective classifi cation 

scheme to capture these types rather than a “one size fi ts 

all” approach. The resultant list of hydromorphological and 

physico-chemical variables that should be considered for 

description of water body types is*:

1. Latitude and longitude 

2. Basin shape 

3. Depth

4. Volume

5. Water residence time

6. Tidal range

7. Climate and seasonality (temperature, light, 

photo-period, precipitation)

8. Sediment substratum (type and rate of 

accumulation)

9. Ratio of catchment size to surface area of estuary

10. Discharge (fl ow source, magnitude, pattern, 

quality) to estuary scaled to area or volume of 

estuary

11. Climatology of salinity immediately outside the 

system (i.e., offshore adjacent coastal waters) at 

monthly to quarterly time frames

12. Salinity within the waterbody

13. Wave climate (sheltered or exposed)

14. Potential Habitat (i.e. what habitats would be there 

in the absence of human intervention)

15. Stratifi cation (seasonal)

16. Sea ice/Ice coverage

*note that the quality of receiving waters is not included 

but might be an additional variable given that ambient or 

unimpacted conditions (e.g. nutrients) might be useful for 

classifi cation of types of systems with very low natural 

levels or those with naturally high levels due, for instance, 

to upwelling.

Recommendations:

• Convene a sub-group of the Update Workshop 

participants, plus others who might be appropriate, to 

proceed with development of a typology classifi cation 

metric or formulation. There should be overlap between 

this group and the Variable sub-group to maximize use 

of data and to validate typology descriptions.

• Use previous NOAA susceptibility work (eg., Quinn 

et al., 1989), previous LOICZ (http://www.kgs.ukans.

edu/Hexacoral/Envirodata/envirodata.html, http://

Figure 4. Photos of four different types of systems. (Pictures 2,3,4 clockwise from upper left: copyright©

2002 Kenneth Adelman, California Coastal Records Project, www.californiacoastline.org)
12

data.ecology.su.se/MNODE/), and European work 

(eg; COAST, 2003; OSPAR, 2001) as a starting point. 

Everything else follows from the typology, including 

selection of variables for eutrophication assessment, 

sampling scheme (spatial and temporal), assessment, 

classifi cation, models and management implication. 

• Use system parameters (residence time, volume, 

depth, stratifi cation, etc.) that affect the system 

sensitivity to nutrient loading rather than classical 

geomorphological classes (coastal plain estuary, 

lagoon, etc.) for typology classifi cation. Classes 

defi ned by these two approaches overlap to some 

extent, but they differ in their emphasis. Selected 

variables should be sub-divided into quantitative 

ranges (categories) with thresholds for ranges set by 

common agreement based on expert knowledge or 

other approaches. The parameter-based approach 

lends itself better to mathematical expression, and 

therefore to mathematical model building.

• Typology should not include water quality issues 

refl ecting degradation which can be added as a data 

layer once the classifi cation is complete, though 

ambient or unimpacted levels of nutrients might be 

useful for separation into types where concentrations 

are naturally very low, or high due to upwelling. 

• Human modifi cation of systems should be noted 

(modifi ed systems may be a “type”). Modifi ed systems 

might be identifi ed by degree of pressure (e.g., 

number of persons per area or volume) or degree of 

response (e.g., percent change in primary productivity 

due to pressure) or degree of structural change (e.g. 

percentage of shoreline modifi cation).

• Limit the total set of types to a manageable number 

(fewer than 10 “common” types).

Monitoring, Assessment and

Classifi cation 

Development of assessment and classifi cation methods 

is a fi rst step toward development of a program that 

integrates the science and management of nutrient related 

problems through appropriate monitoring, assessment, 

modeling, and research. Assessment methods will be 

used to classify the status and to track nutrient-related 

problems over time, with the intent of guiding development 

and evaluating the success of management actions and in 

support of research. Additionally, modeling will be helpful 

for understanding how human impacts of eutrophication 

can be more effectively managed (Figure 5).

The type classifi cation should be a fi rst step since the 

variables appropriate for accurately characterizing nutrient 

related water quality conditions are ultimately type related, 

as are appropriate spatial and temporal considerations for 

sampling (Figure 6). 

Nutrient Related Eutrophication

Workshop participants developed two lists of variables; a 

core set of variables that should be measured in all types 

and an enhanced set of variables that is specifi c to a type 

of estuary/coastal water or its specifi c eutrophication 

status (see lists following; Figure 7). It should be noted 

that some core variables may not be applicable to all types 

Figure 5. Flow diagram for adaptive management 

framework. 

Airshed

Coastal

Watersheds

Large 

Upstream 

Watersheds

Coastal Water Body

Wetlands Open Ocean

Exchange

Smaller Streams

Figure 6. Schematic showing general sources of nutrients 

and main route of transport to coastal waters.
13

of estuaries and coastal waters, for instance, sea grasses 

are nonexistent in South Carolina estuaries. It should 

also be noted that variables that would be monitored for 

management purposes might only partly overlap with the 

variables that would be monitored in support of research

It is important to defi ne the variables to be measured in 

order to answer questions, both conceptual (i.e. what is 

there) and mathematical (i.e. to predict what might be 

there). Models might further be used to narrow the fi eld of 

core variables, in addition to their use to better understand 

nutrient input / water body response relationships in 

pursuit of effective management options. The outcome 

of this monitoring and assessment program should be 

geared toward giving resource managers what they need, 

when they need it, to do their jobs effectively. The intent is 

to provide a constant data stream that can be used for the 

development of status, trends, and predictions for nutrient 

related eutrophication (Figure 8). Workshop participants 

developed the following core and enhanced variables for a 

long-term monitoring and assessment program: 

Possible Core Variables Depending on Estuarine/

Coastal Water Types

1. Salinity

2. Temperature (global/regional, seasonal, climate) 

3. Meteorological data

4. Water residence time

5. Turbidity, KD

6. Chl a*

7. Seagrass*

8. Macrophytes*

9. Benthic algae*

10. Phytoplankton*

11. Dissolved Oxygen – relative to diel variability

12. Sediment organic content

13. Dissolved nutrients (NO3

-

, NO2

-

, NH4

+, PO43-, Si)

14. Total nutrients (TN, TP)

15. N:P:Si ratios

16. Freshwater Flow, nutrient concentration, load

17. Seawater exchange, nutrient concentration, load

18. Anthropogenic and natural nutrient loads

19. Point sources

20. Nonpoint sources (e.g. atmospheric)

*Changes in biomass, percent composition, aereal 

coverage: i.e. areal coverage for phytoplankton refers to 

the areal extent of blooms of very high concentration of Chl 

a as in the NEEA (Bricker et al., 1999).

Possible Enhanced Variables Depending on 

Estuarine/Coastal Water Types

1. TSS

2. Depth range of macrophytes

3. HPLC pigments - Taxon specifi c

4. Benthic community composition. and structure

5. SOD/BOD

6. Stable Isotopes 

7. Heavy metals (Ex. Fe)

8. Harmful Algal Blooms (HABs)

Figure 8. CTD deployment.

Figure 7. CHL a, DO, DIN, DIP plots for Chesapeake and San 

Francisco Bays (Cloern, 2001). 
14

Other Important Variables and Rates

1. Fish stocks

2. Land use

3. Population changes

4. Sediment fl uxes

5. Internal nutrient cycling

It is very important to consider that the minimum temporal 

and spatial resolution necessary for characterization 

is dependent on typology. Depending upon the type of 

system and variables being measured, sampling frequency 

could vary through the year with highest frequency during 

the growing season and lowest frequency during the lowgrowth season. Quality control in data acquisition and 

processing should be assured and encouraged.

Participants agreed that it was likely that thresholds for 

measured variables, marking the levels above which 

water quality is considered undesirable, will be different for 

different types of estuaries and coastal systems, and the 

scales (i.e. high, medium, low) will require normalization for 

synthesis of the regional and national pictures, e.g. through 

the use of rating curves. Determination of thresholds for 

different types of systems requires considerable caution 

in application. As an example: dissolved oxygen in the 

water dictates the ecology, but thresholds set in absolute 

concentration may differ widely between regions depending 

on local (particularly temperature) conditions. For example, 

two widely differing values between the northern U.S. and 

the Gulf of Mexico may actually correspond to an identical 

value in percentage saturation. 

It is also important to note that some parameters, such 

as harmful algal blooms, are not always amenable to 

management. While some blooms within estuarine 

systems are triggered by nutrients, others are not. This 

occurs, for instance, in parts of the U.S. Pacifi c, Gulf of 

Mexico, and North Atlantic coasts with the formation of 

toxic algal blooms in offshore frontal systems, which are 

then advected into estuarine areas. In addition, the link 

between toxic algal forms and nutrients is not always well 

established.

Socioeconomic Impacts to Human Uses

This component of the assessment is intended to evaluate 

the impact of nutrient related water quality problems on 

various human uses of the water bodies. This was not 

explored thoroughly in the NEEA and is the least developed 

of all the assessment components. Workshop participants 

agreed that the design of an economic analysis of the 

linkage between nutrient pollution effects and uses of 

estuaries and coastal waters was beyond the scope of 

their expertise. It was recognized that development of 

socioeconomic models of the impacts of human related 

eutrophication would be a signifi cant addition to the 

assessment update. A recommendation was made that 

additional social scientists and economists with experience 

in economic impact analysis linking water quality and human 

use impairments be invited to participate in development of 

this component.

Recommendations

• Convene a sub-group of the workshop participants, 

some from the “Typology” sub-group, to proceed 

with selection of core and enhanced variables for 

the different types. This group should also address 

spatial and temporal sampling considerations, such 

as segmentation of estuarine/coastal water types by 

salinity or some other basis, and how to combine data 

for different segments. Determination of reference 

values, as well as thresholds for category ranges, 

methods for combining variable data into an overall 

score, and other methods, should also be developed 

by this sub-group. The assessment results should be 

comparable on a national basis.

• Convene a sub-group from members of the “Typology” 

and “Monitoring, Assessment and Classifi cation” 

sub-groups to develop nutrient input/water body 

response (and other) models that address and 

inform management options. Model development will 

draw from results of the “Typology” and “Monitoring, 

Assessment, and Classifi cation” subgroups.

• Use 3-4 core variables that are measured in all 

types, and additional (enhanced) variables that are 

tailored to specifi c types of systems to get an accurate 

characterization of conditions. The core parameter 

set will be identical for all types when dealing with 

a particular issue, although there may be additional 

enhanced parameters for systems within a specifi c 

type to more accurately characterize conditions for 

systems within that type.

• Support research for variables that show promise as 

indicators but need more research to link pressure 

to response and use new probes (e.g., new nitrate 

sensors, optical sensors, chlorophyll probes, etc.). 

Use new technologies (e.g., meters and probes) as 
15

they become available to obtain data of concern. 

Incorporation of new technologies should begin at the 

auxiliary level and not as primary methods. Work with 

EPA on changing methods of data collection to gain 

acceptance/approval for regulatory purposes.

• Use a suite of variables that is manageable. 

These should be used to develop indicators for 

characterization of status and for “early warning” of 

impending problems. 

• Convene a sub-group composed of workshop 

participants, social scientists, and economists who 

have experience in economic impact analysis to 

develop an approach for determining what society’s 

uses of systems are and methods for linking nutrient 

related water quality impacts to changes in those uses 

and their socioeconomic costs.

• Use sediment cores to determine past trends in order to 

fi nd variables that have infl uenced conditions in the past 

and to provide an historical framework for interpretation 

of present and possible future conditions.

• Assure quality control in data acquisition and 

processing, both within a system and between systems, 

types, and regions. Pooling data is a huge asset to this 

kind of project and should be encouraged.

Modeling and Management of 

Eutrophication

The results of the “Typology” and “Monitoring, assessment 

and classifi cation” groups should be used to develop 

models to better understand the response of different 

types of water bodies to varying nutrient input levels. 

These models can then instruct and guide development 

of appropriate management alternatives for different 

systems dependent upon type and level of impairment. In 

addition, model scenarios should be used to predict what 

might occur with changes in loadings (Figure 9). These 

models and results should be provided to managers for 

optimization of adaptive management success.

Proper adaptive management of eutrophication has to 

implement effective abatement measures, and also to fulfi ll 

the following two general objectives:

1) Translation and integration of science into 

information and tools that are useful to managers.

2) Reporting of results to the public and to Congress 

to leverage action (i.e. changes in legislative 

mandates) and funding for management and 

related research. 

Communication between managers and researchers about 

research and monitoring results is critical to appropriate 

and successful management, however, it is not suffi ciently 

developed at present. Managers need data and information 

on specifi c time and spatial scales in order to manage 

resources appropriately. For example, states typically get 

blocks of data for a 5 year time period, which matches the 

life span of permits but is not useful for analyzing episodic 

and/or brief events such as algal blooms. Sometimes, 

long-term data are necessary for understanding short-term 

events and natural variability within a system. 

Managers must articulate to the scientists what they need 

and when they need it. Scientists, in turn, must provide data 

and results in forms that are useful to managers. This might 

take the form of an “Operational Oceanography” interface 

between scientists and managers but the interface needs 

to be developed. This interface represents a continuous 

collection of data that can be used at any time to assess 

the status and trends in nutrient related problems, and uses 

historical and current data to make predictions, similar to 

the methods the weather service uses for forecasts. 

Scientists should help managers by outlining what 

monitoring and research is being done and how that 

can help them to manage. Screening models and other 

analytical tools should be developed for identifying 

Figure 9. Comparative evaluation of fi shery response to nutrient 

loads in the Gulf of Mexico (CENR, 2000).
16

susceptibility to nutrients, including what variables must 

be monitored (and on what time scales) to detect changes 

in the system and when the system is above the threshold 

of desirable conditions. For example, a simple web-based 

screening template or tool could allow resource managers 

to easily determine the approximate status of an estuary or 

coastal water. Once the types of estuaries are described 

and referenced as well as threshold values of concern 

identifi ed for each type, an on-line program could be set 

up so that a manager could:

1. Enter the estuary/coastal water body type (e.g., 

shallow, river dominated, coastal etc.), which would 

then bring up the appropriate variables associated with 

monitoring in that type of system. The manager could 

then enter measured values for those variables.

2. Threshold levels for that type of system would then be 

compared to the measured values. Variables above 

the threshold would be fl agged.

3. Depending on the combination of variables found to 

be above threshold levels, the web-based tool would 

be able to provide the overall status of the water body 

and recommend appropriate levels of action. In cases 

where there are a limited number of systems within a 

type, the program could be preloaded with typological 

data (retention time, fresh water infl ow, etc) for 

individual systems making the characterizations more 

accurate. 
17

The web-tool output could also provide information on how 

the system was coded by the original NEEA and provide 

a summary of the data (i.e. number of records, range, 

median, mean, etc). The output should also be put into a 

comparative regional and national perspective which can 

be used to set priorities for funding.

Improved public outreach is necessary to convey 

information on nutrient related eutrophication impacts 

and success of management efforts in such a way that 

they are meaningful to the public. These efforts should 

include development of the linkage between the impacts of 

nutrients in an estuary/coastal water and society’s uses of 

these waters. Impact valuations are key and necessary to 

convince the public and legislature to support research and 

management efforts. As an example, in Sarasota Bay, the 

mayor and city council were much more enthusiastic about 

creating habitat that might support 300 million additional 

fi sh, though small, than they were about secchi disk depths 

increasing by 25 % and seagrass meadows increasing by 

700 acres. This demonstrates how this approach will serve 

to develop public support for management.

 

Recommendations

• Develop an organizing framework for states’ managers, 

that includes a translation mechanism from the science 

to the managers that should include: descriptions of 

the susceptibility of systems to nutrients, the indicators 

that should be monitored to understand the direction 

and magnitude of change in water quality, and the 

thresholds that prompt policy and management 

changes. 

• Develop an operational observation system that 

routinely provides data and information to managers 

on appropriate time frames and in the most useful 

format. Use the idea of “Operational Oceanography” 

interface between scientists and managers.

• Develop models and analytical tools for management 

purposes. 

• Identify a Steering Group to guide further development 

of the monitoring and assessment program.

• Determine sub-group membership for “Typology” and 

“Monitoring, assessment and classifi cation” (including 

reference conditions and classifi cation issues, such 

NEXT STEPS

as variable thresholds), “Modeling and Management” 

(for development of an operational framework and 

analytical tools) and write the scope-of-work for the 

groups. Overlap among groups is key.

• Identify and contact appropriate economists and 

social scientists for participation and guidance on 

development of the economic impacts/society’s uses 

component.

• Compile a summary of data in preparation for selection 

of candidate estuaries for a pilot study (include search 

for models of susceptibility and input/response, such 

as that for Tampa Bay).

• Begin designing pilot studies.
18

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21
April 2004