EPA

United States Office of Water EPA 822-R-98-002

Environmental Protection 4304 June 1998

Agency

National Strategy for the

Development of Regional

Nutrient Criteria

June 1998
ii

CONTENTS

PREFACE BY ROBERT PERCIASEPE, ASSISTANT ADMINISTRATOR, OFFICE OF

WATER ................................................................. iii

NOTE TO THE READER ................................................... vi

I. INTRODUCTION ..................................................... 1

A. Background ........................................................ 1

B. Nutrient Pollution Problems ............................................ 2

C. Past Nutrient Reduction Efforts ......................................... 2

D. Other Current Nutrient-Related Efforts ................................... 3

II. THE NATIONAL NUTRIENT STRATEGY ................................ 5

A. The Five Key Elements of the Strategy ................................... 6

B. How the Elements are Integrated ....................................... 14

III. WATERBODY-TYPE TECHNICAL GUIDANCE ........................... 15

A. Indicators ........................................................ 17

B. Data Storage and Processing .......................................... 22

C. Management and Evaluation .......................................... 25

D. Research Needs .................................................... 30

APPENDIX A: Summary of Water Quality Criteria and Standards for Nutrient 

Overenrichment ............................................. 35

APPENDIX B: Nutrient Criteria Activities and Timeline ........................... 41

APPENDIX C: Draft Outline for the Development of Nutrient Criteria for Rivers,

Lakes, Reservoirs, Estuarine and Coastal Systems .................... 45

APPENDIX D: Drafting Committee for the National Nutrient Strategy ................ 49

APPENDIX E: Excerpt from the Clean Water Action Plan ......................... 50

REFERENCES ............................................................ 52
iii

PREFACE

In February of this year, President Clinton and Vice President Gore released a 

comprehensive Clean Water Action Plan. The Action Plan provides a blueprint for Federal

agencies to work with States and others stakeholders in restoring and protecting the Nation’s

water resources and addresses three major goals: 

C enhanced protection from public health threats posed by water pollution;

C more effective control of polluted runoff; and 

C promotion of water quality restoration and protection on a watershed basis. 

A key part of the Action Plan provides for expanded efforts to reduce nutrient

overenrichment of waters. 

Nutrients, in appropriate amounts, are essential to the health of aquatic systems. 

Excessive nutrients, however, can result in excessive growth of macrophytes or phytoplankton

and potentially harmful algal blooms leading to oxygen declines, imbalance of aquatic species,

public health threats, and a general decline in the aquatic resource. 

Recent reports on water quality conditions provided by States indicate that nutrients are

the leading cause of impairment in lakes and coastal waters and the second leading cause of

impairment to rivers and streams. Nutrient overenrichment has also been strongly linked to the

large hypoxic zone in the Gulf of Mexico and to recent outbreaks of the toxic microorganism

Pfiesteria along the Gulf and Mid-Atlantic coasts. 

The Action Plan calls on EPA to accelerate the development of scientific information

concerning the levels of nutrients that cause water quality problems and to organize this

information by different types of waterbodies (e.g. streams, lakes, coastal waters, wetlands) and

by geographic regions of the country. EPA is also to work with States and Tribes to adopt

criteria (i.e. numeric concentration levels) for nutrients, including nitrogen and phosphorus, as

part of enforceable State water quality standards under the Clean Water Act. 

 This National Strategy for Development of Nutrient Criteria describes the approach

that EPA will follow in developing nutrient information and working with States and Tribes to

adopt nutrient criteria as part of State water quality standards. Some key aspects of the Strategy

are described below. 
iv

Region and Waterbody Approach

Section 304(a) of the Clean Water Act directs EPA to develop scientific information on

pollutants and to publish “criteria guidance,” often expressed as pollutant concentration levels,

that will result in attainment of a designated use of the waterbody (e.g. fishing, swimming) that is

determined by the State. These concentration levels generally are the same for all types of

waterbodies and to all areas of the country. States consider these EPA “criteria guidance” when

they adopt water quality standards for waterbodies. A water quality standard commonly includes

a designed use for the waterbody and criteria (i.e. concentration levels) for a range of pollutants

that will assure that the waterbody will support the designated use. 

In the case of nutrients, however, there is a great deal of variability in inherent nutrient

levels and nutrient responses throughout the country. This natural variability is due to differences

in geology, climate and waterbody type. Because of this variation, EPA's custom of developing

scientific information about a pollutant and recommending a single pollutant concentration

number to support a designated use for nationwide application is not appropriate for nutrients. 

EPA believes that distinct geographic regions and types of waterbodies need to be evaluated

differently and that recommended nutrient concentration levels need to reflect geographic

variation and waterbody types. 

Waterbody-Type Guidance Documents

An essential element of this Strategy is development of waterbody-type guidance

documents describing the techniques for assessing the trophic state of a waterbody and

methodologies for developing nutrient criteria appropriate to different geographic regions. 

Separate guidance documents will be developed for rivers, lakes, coastal waters, and wetlands. 

Each waterbody guidance document will provide scientific information required by section

304(a) of the Clean Water Act, including recommended nutrient concentration levels that are

appropriate for the waterbody type, the geographic region, and various designated uses. EPA will

use State databases to develop these criteria guidance documents, supplemented with new

regional case studies and demonstration projects to provide additional information. EPA expects

that these levels will be expressed as numerical target ranges for variables such as phosphorus,

nitrogen, and other nutrient indicators. Guidance documents for rivers, lakes, and coastal waters

will be completed by the end of the year 2000 and the guidance document for wetlands will be

developed by the end of 2001. 

Adding Nutrients to Water Quality Standards

EPA expects States and Tribes to use the waterbody type guidance documents and

nutrient target ranges as a guide in developing and adopting numeric levels for nutrients that

support the designated uses of the waterbody as part of State water quality standards. EPA will

work with States to support and assist in this process. States should have adopted nutrient

criteria that support State designated uses by the end of 2003. 

EPA will review and approve the new or revised nutrient elements of water quality
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standards under Section 303(c)(3) of the Clean Water Act. If EPA disapproves the new standard

submitted by a State or Tribe (because EPA determines that it is not scientifically defensible), or if

EPA determines that a new or revised nutrient standard is necessary for a State or Tribe (because

EPA determines that the State or Tribe has not demonstrated reasonable progress toward

developing numerical nutrient standards), EPA will initiate rulemaking to promulgate nutrient

criteria values that will support the designated use of the waterbody and are appropriate to the

region and waterbody types. Any resulting water quality standard would apply until the State or

Tribe adopts, and EPA approves, a revised standard.

Once adopted as part of State or Tribal water quality standards, the nutrient criteria in

State standards will become the basis for identifying waters where nutrients result in impairment

of water quality and making many management decisions to reduce excessive nutrient levels in

these waters. 

National and Regional Nutrient Teams

The Office of Water will provide additional technical and financial assistance to the

Regions and States to accelerate the development of nutrient criteria. 

This effort will include the establishment of a National Nutrient Team, including

coordinators from each EPA Region. The Regional Coordinator will foster the development and

implementation of State projects, databases, nutrient criteria and standards, and the award of

financial assistance to States and Tribes to support these endeavors. Each Regional coordinator

will be responsible for nutrient management activities for that Region and its member States and

Tribes consistent with decisions of the national nutrient program. 

Each Regional Coordinator will form a Regional Nutrient Team that includes State and

Tribal representatives and other federal and local representatives, as needed, to develop nutrient

databases and nutrient target ranges.

I am confident that this effort to include nutrient concentration levels in State water

quality standards will be a major step forward for efforts to restore and protect the Nation’s

waters. I look forward to working with water program managers and other interested parties in

this important initiative. 

 

 

Robert Perciasepe Date

Assistant Administrator

Office of Water
vi

NOTE TO THE READER

This document sets forth EPA’s strategy to develop scientific information (i.e., criteria documents

under section 304(a) of the Clean Water Act) which EPA will recommend that States use to

adopt nutrient criteria to support State water quality standards. These nutrient criteria provide a

critical foundation to address overenrichment problems in the Nation’s surface waters. It also

provides guidance to States, Tribes and the public regarding how EPA intends to exercise its

discretion in implementing the provisions of the Clean Water Act concerning the adoption of

water quality standards. 

This document is designed to implement national policy on the issues it addresses. It does not,

however, substitute for the Clean Water Act or EPA’s regulations; nor is it a regulation itself. 

Thus, it cannot impose legally binding requirements on EPA, States, Tribes or the regulated

community and may not apply to some particular situations. EPA, State and Tribal

decisionmakers retain the discretion to adopt approaches on a case-by-case basis that differ from

this guidance where appropriate. EPA also retains discretion to change the guidance contained in

this strategy in the future.
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I. INTRODUCTION 

A. Background

Nutrients, in the appropriate amounts, are essential to the health and continued functioning of

natural ecosystems. Depending upon specific characteristics of the receiving waterbodies, they

can be present in excessive, limiting, or optimal amounts. Insufficient nutrients will result in less

than optimal growth of primary producers (i.e., plants, including phytoplankton and submerged

aquatic vegetation). Adequate primary productivity is essential to support all the other trophic

levels and a healthy, diverse, and productive ecosystem. 

Excessive nutrient loadings will, however, result in excessive growth of macrophytes or

phytoplankton and potentially harmful algal blooms (HAB), leading to oxygen declines, imbalance

of prey and predator species, public health concerns, and a general decline of the aquatic resource. 

It is the excesses of these nutrients resulting from human activities, rather than natural spatial and

temporal variations, that are the concern of this document and it is this cultural eutrophication

that is most appropriately the subject of management efforts.

When nutrient inputs exceed the assimilative capacity of a waterbody system, the system

progresses toward hypereutrophic conditions. Symptoms include an overabundance of primary

producers, decreased biological diversity, algal blooms (some toxic), low dissolved oxygen,

episodic anoxia, loss of vascular plant life, and fish kills. Investigations have shown that the key

causative factors are excessive concentrations of the primary nutrients phosphorus and nitrogen.

The term nutrient is loosely used to describe a compound that is necessary for metabolism. 

Nitrogen (N) and phosphorus (P) are required in relatively large amounts by cells and are called

macronutrients, as opposed to micronutrients such as iron or molybdenum. 

Nutrient criteria is intended to be interpreted in its broadest sense, covering both legal and

scientific interpretations. Legally, a nutrient criterion is the numeric value which supports a

particular beneficial designated use in defining a water quality standard. Scientifically, a nutrient

criterion is meant to encompass both causal and response variables (e.g., nitrogen or phosphorus

levels), as well as aquatic community response parameters such as but not limited to algal

biomass, chlorophyll a, and secchi depth. 

Similarly, in this text the problem of eutrophication is used to describe an increase of nutrients in

a waterbody which results in an overabundance of plant biomass (Flemer, 1972). 

The terms water quality measurement and water resource measurement are both intended to

mean a comprehensive array of measurements including chemical, physical, and biological

parameters.

In all aquatic ecosystems some general processes determine whether N or P is the limiting

macronutrient and can be expressed as the nitrogen-to-phosphorus ratio (N:P). The Redfield

ratio of N:P for primary producers in marine systems is approximately 16:1 on a molar scale
2

(Redfield, 1958). In freshwater systems the phosphorus limitation tends to be greater at an N:P

ratio of up to about 26:1. Ecosystems that deviate substantially from these ratios are likely to

experience nutrient limitation of either N or P (i.e., if the ratio in marine or estuarine waters is less

than 16, N could be limiting; if the ratio is greater than 16, P is probably the limiting nutrient).

B. Nutrient Pollution Problems

According to the U.S. Environmental Protection Agency’s (EPA’s) National Water Quality

Inventory: 1996 Report to Congress (required under section 305(b) of the Clean Water Act) , 50

States, Tribes, and other jurisdictions surveyed water quality conditions in 19 percent of the

Nation’s total 3.6 million miles of rivers and streams. 

Some 36% of these surveyed waters were impaired by various pollutants. The leading cause of

impairment was siltation, contributing to impairments in 51% of these waters. Nutrients were the

second most significant cause of impairment, contributing to impairment of 40% of waters. 

Excessive nutrients were the leading cause of impairment of affected lakes and impaired coastal

waters at 51% and 57% respectively.

Excessive nutrients have also been linked to hypoxia conditions in the Gulf of Mexico and have

been associated with outbreaks of Pfiesteria in several Gulf and Mid-Atlantic States.

Sources historically associated with nutrient overenrichment are fertilizers, sewage treatment

plants, detergents, septic systems, combined sewer overflows, sediment mobilization, animal

manure, atmospheric deposition and internal nutrient recycling from sediments. Other factors that

can influence overenrichment are light attenuation, land-use practices, and imbalance of primary,

secondary, and tertiary producers and consumers (plankton, macrophytes, epiphytes, grazers,

predators, and decomposers).

C. Past Nutrient Reduction Efforts

Over the years, the EPA’s Office of Water has issued a number of technical guidance documents

and has supported the development of water quality simulation models and loading estimating

models that can be used to assess the impacts of urban, rural, and mixed land use activities on

receiving waters. 

In addition, some States currently have water quality standards that incorporate criteria, primarily

narrative, aimed at controlling problems associated with nutrient overenrichment (see Appendix A

for a list of water quality criteria and standards currently in use by States). However, for State,

Tribal and local agencies to better understand and manage nutrient impacts to surface waters,

additional work is necessary.
3

According to a State Nutrient Water Quality

Standards 1994 EPA Survey:

Ç 17 States have no WQS for nitrates/nitrites

Ç 21 States have no WQS for phosphorus

Ç Many States have narrative standards only

Ç 10 States have adopted EPA criteria unrelated

to eutrophication (e.g., 10 mg/L for nitrate, or 

0.10 ug/L elemental phosphorus)

Ç Only 9 criteria (N and P) are waterbody-based

In 1993, the EPA Nutrient Task Force gathered existing data on nutrient problems and currently

available tools. It recommended that EPA provide additional assistance to States in developing

and implementing appropriate nutrient indicators, assessment methodologies, and models. The

first step in carrying out the recommendations of the task force was the nutrient overenrichment

assessment workshop held in Washington, DC, on December 4-6, 1995. The workshop was

organized around plenary and breakout group discussions on four major waterbody types: 

C estuarine and coastal marine water; 

C lakes, impoundments/reservoirs, and ponds; 

C rivers and streams; and

C wetlands. 

Issue papers describing the state of the science, gaps, and user needs in terms of nutrient

assessment tools and methodologies for each waterbody type were developed and used as

foundations for these group discussions. The results of this workshop, compiled in National

Nutrient Assessment Workshop Proceedings (EPA 822-R-96-004, 1996), form the basis of this

Strategy. 

D. Other Current Nutrient-Related Efforts

In addition to this Strategy, there are a number of other evolving efforts that focus on elements

related to the nutrient overenrichment problem. These include the following:

C Criteria and Standards Plan. The Plan describes six new criteria and standards 

program initiatives that EPA and the States/Tribes will pursue over the next

decade including the nutrient criteria effort. The Plan presents a “vision” and

strategy for meeting these important new initiatives and improvements. The Plan

will guide EPA and the States/Tribes in the development and implementation of

criteria and standards and will provide a basis for enhancements to the Total

Maximum Daily Load (TMDL) program, National Pollutant Discharge Elimination

System (NPDES) permitting, nonpoint source control, wetlands protection and

other water resources management efforts.

C Nonpoint Sources: Picking Up the Pace; A National Strategy for

Strengthening Nonpoint Source Pollution Management (draft, September
4

1997). This strategy envisions that all States/Tribes, with the active assistance and

participation of all stakeholders, will implement dynamic and effective nonpoint

source pollution programs to achieve and maintain beneficial uses of water by the

end of calendar year 2013.

C Strategy for Addressing Environmental Public Health Impacts from Animal

Feeding Operations (AFOs) (draft, March 1998). This strategy strives to

minimize environmental and public health impacts from AFOs through an effective

mix of voluntary and regulatory measures. EPA is working with the US

Department of Agriculture to develop a joint USDA/EPA national strategy on

Animal Feeding Operations. This joint strategy -- which will supersede the draft

EPA AFO Strategy -- will be published in draft form in July and in final form in

November.

C The National Harmful Algal Bloom Research and Monitoring Strategy. This

strategy was developed as an effort to coordinate Federal research and monitoring

activities on Pfiesteria and other HABs. Federal HAB programs are spread across

several Federal agencies, including the National Oceanic and Atmospheric

Administration (NOAA); EPA; the Department of Health and Human Services–

Centers for Disease Control and Prevention, the Food and Drug Administration,

and the National Institute of Environmental Health Sciences (DHHS– CDCP,

FDA, and NIEHS); the National Biologic Service (NBS); the National Science

Foundation (NSF); and the U.S. Fish and Wildlife Service (USFWS), and an

interagency workgroup was formed to address a diverse list of current and planned

HAB activities. 

After reporting relevant research and programmatic activities, questions were

formulated that addressed the objectives of a comprehensive research strategy. 

The research questions and objectives were differentiated into near-term and longterm activities, and the workgroup classified each agency activity into groups that

reflect the eight objectives cited in Marine Biotoxins and Harmful Algae: A

National Plan (Anderson et al., 1993). Agency activities have been categorized

into these objectives allowing the workgroup to identify obvious coordination

points, and data/research gaps. 

C Water Quality Standards Regulation: Advance Notice of Proposed Rule

Making (ANPRM). EPA is about to publish an Advance Notice of Proposed

Rulemaking (ANPRM) on the Water Quality Standards Regulation in the Federal

Register. The ANPRM solicits public comment on potential revisions to the basic

water quality standards program regulation governing State adoption and EPA

approval of water quality standards under Section 303(c) of the Clean Water Act. 

The ANPRM also requests comment on changes in policy and guidance that

support the regulation. 

The ANPRM expresses current EPA thinking in a number of areas addressed by

the current regulation, policy and guidance and requests comment on that thinking. 
5

One of the main themes of the ANPRM is updating and modernizing water quality

standards so that standards may be better implemented on a watershed basis using

refined use designations and tailored criteria. New science and assessment

methodologies, as well as better data, and new types of data and analysis would

need to be used by States and Tribes to refine water quality standards in this

manner. The ANPRM highlights the potential resource challenge for States and

Tribes and requests comment regarding concerns over resource constraints and

ideas for how to address them. 

C The USDA Nutrient Management Policy. The USDA’s Natural Resources

Conservation Service (NRCS) proposed a revised nutrient management policy to

its National Agronomy Manual. This revised policy will impact the NRCS national

conservation practice standards for Nutrient Management (Code 590) and Waste

Utilization (Code 633). The nutrient policy discusses certification of plans,

describes what is in nutrient management plans, and discusses soil and plant tissue

testing, nutrient application rates, record keeping and other special considerations. 

The revised policy will be adopted after the June 22, 1998 comment period closes. 

The groups developing the strategies are all investigating related problems ... land use-nutrient

loading relationships, ecological responses, and appropriate mitigation activities. As all of these

strategies progress, it will be essential to coordinate the information and activities that result so

that consistent policy is developed.

II. EPA NATIONAL STRATEGY FOR DEVELOPING REGIONAL NUTRIENT

CRITERIA 

This Strategy proposes to build on the work accomplished to date and to establish an objective,

scientifically sound basis for assessing nutrient overenrichment problems. Improving the basis for

assessing nutrient overenrichment problems will provide critical support for expanded efforts to

control nutrient levels in waters and meet the Nation’s clean water goals. 

Specifically, this Strategy proposes a two-phase process for the development of water quality

standards for nutrients:

1) EPA will develop “nutrient criteria guidance” for nitrogen, phosphorus,

and other nutrient parameters such as chlorophyll a, secchi depth, and algal

biomass. These criteria will be developed under section 304(a) of the

Clean Water Act and will represent EPA’s guidance regarding the amounts

of those contaminants that may be present in waters without impairing their

designated uses. Unlike other criteria guidance that EPA has developed,

EPA intends to express nutrient criteria guidance as numerical ranges,

reflecting a menu of different values based on the type of waterbody (i.e.,

streams and rivers, coastal waters and estuaries, lakes and reservoirs, and

wetlands) and the region of the country in which the water is located. 

2) EPA expects States and Tribes to adopt nutrient water quality criteria
6

(including N and P concentration levels) to support designated uses of

waters. These “nutrient criteria” will be based on EPA’s nutrient criteria

guidance or other scientifically defensible methods and will be incorporated

into the States’ water quality standards. The goal is for the States/Tribes

to establish these criteria as part of their water quality standards as soon as

the appropriate criteria guidance is developed. The target date for

adoption of nutrient criteria as part of water quality standards is within

three years of completion of the guidance, (i.e., by the end of the calendar

year 2003). EPA will step in and promulgate nutrient water quality criteria

for a State or Tribe if EPA determines that federal action is necessary.

Adding nutrient criteria to State water quality standards is essential for Federal,

State and local agencies, and the public, to better understand, identify, and manage

nutrient overenrichment problems in surface waters. 

The following sections will present the key elements of the Strategy and describe the tasks and

activities that EPA will undertake to promote nutrient assessment and criteria development over

the next several years.

A. The Five Key Elements of the Strategy

1) Geographic Region Approach. 

EPA intends to develop nutrient criteria guidance on a regional, rather than a national, basis. The

Agency expects States and Tribes to develop water quality criteria and standards for nutrients in

their geographic regions based on the guidance provided by EPA. The criteria established would

therefore be the product of a joint EPA-State/Tribal effort tailored to that part of the country. 

This approach permits the objective of overenrichment abatement to be met by recognizing the

ambient “natural” background levels of nutrients in each region and then concentrating on the

“cultural” eutrophication which exceeds this. As noted below, regional criteria information will

be presented for four categories of waterbodies.

Although this Strategy is organized around the four major waterbody types specified below, it is

recognized that approaches for assessing regional and waterbody-specific nutrient concerns must

consider that waterbody types are not independent from each other, but are part of an

interconnected and larger system. With that in mind, the need for integration of concepts

associated with the assessment and control of nutrient overenrichment between waterbody types

is clear. This understanding of an integrated approach is an important concept to keep in mind

during the implementation of this Strategy.

One well-defined spatial framework which can be used to define a region for nutrient assessment

is the “ecoregion” system developed by James Omernik of the EPA Corvalis, OR laboratory. 

While it is acknowledged that several other classification schemes have been developed, for the

purposes of this strategy, EPA plans to use Ecoregions as defined by Omernik et al., to initiate

development of regional nutrient indicator ranges and, ultimately, to include them in the State and

Tribal nutrient water quality criteria. A draft map has been created as a starting point for this
7

process (See figure 1). Still to be determined is what scale of ecoregion is appropriate for the

development of regional nutrient criteria guidance within a short period of time (by the end of

calendar year 2000). The degree of variability within each of these 14 nutrient ecoregions will

determine whether the map needs further refinement. These issues will be resolved once data has

been reviewed, analyzed, and discussed at meetings of the National Nutrient Team and its

Regional components (see item 4 below). In addition, this does not preclude the use of other

classification schemes by Regions and States and Tribes if they are judged to be more appropriate

for that part of the country. For more details on the ecoregion concept and how it can be applied

in a nutrient assessment see Omernik (1995) and Omernik et al (1988).

Upon determination of the best ecoregion scale, the next task which is integral to the development

of nutrient ecoregional ranges is the identification of reference conditions within each of the

nutrient ecoregions. Reference conditions refer to information from relatively undisturbed areas

within each ecoregion. The concept of reference conditions and how they are selected will be

described in more detail in the technical guidance documents.

2) Waterbody-Type Technical Guidance. 

 A major element of this Strategy will be the technical nutrient criteria guidance manuals, which

will provide methodologies for developing region-specific nutrient criteria by waterbody type: 

C streams and rivers,

C lakes and reservoirs,

C estuaries and coastal marine waters, and 

C wetlands.

These manuals will also include discussions on overenrichment indicators, sampling and analytical

techniques, and management methods. The manuals will be designed to be adapted in the various

regions of the country.

The manuals will also provide technical assistance to implement nutrient abatement practices and

will include data processing and manipulation techniques, best management practices, and case

study demonstrations. An outline of the proposed content of the guidance document is in

Appendix C, and elements of the technical material are presented in part III of this document. 

EPA plans to publish guidance documents for streams and rivers, and lakes and reservoirs in

1999; a guidance document on estuaries and coastal marine waters in 2000; and a guidance

document on wetlands in 2001. In each document, where data is available, EPA will also

provide target regional nutrient ranges for phosphorus and nitrogen (and potentially other

parameters), which States and Tribes may elect to use as the basis of their nutrient criteria and

standards in lieu of applying the methodology. Where appropriate, they may also use these values

as the basis for TMDLs and NPDES permit limits. 

EPA and the Regional teams will collect and organize nutrient data on a geographic basis and

develop target nutrient ranges based on historical nutrient data, reference conditions, and expert 
8
9

panel opinion. Where adequate data is available, EPA intends to append these ranges to its

waterbody-type guidance manuals. This information can be used by individual States/Tribes

which lack sufficient data of their own. Each appendix will be a “stand alone,” peer reviewed

document for a specific nutrient ecoregion. 

As a preliminary measure for development of these nutrient criteria ( i.e., the particular indicators

used to assess the overenrichment or potential for overenrichment of a waterbody), EPA is

seeking the cooperation of States and Tribes to pool available information in the determination of

such ranges of target values for each region of the country. EPA will initially develop ranges for

phosphorus, nitrogen, chlorophyll and secchi depth. 

Collecting the data necessary to establish ranges for these parameters will be the first priority of

the National Nutrient Team and Regional Coordinators. These ranges are intended to reflect the

variability of conditions typically associated with particular waterbody types within an ecoregion. 

In addition, the ranges of target values serve as a starting point for making the proper

measurements of waterbody enrichment and overenrichment so the appropriate management can

be initiated. The guidance manuals are designed to provide the best methods for such measuring

and evaluation.

An essential element of this process is the determination of the natural, background trophic state

representative (Reference condition) of that area and waterbody so that abatement management

can be directed at the cultural eutrophication of concern. It is not the intention of this strategy or

the subsequent program to require States or Tribes to correct a natural enrichment process typical

of their region; rather it is the purpose of the strategy to help States and Tribes develop

mechanisms to remedy the enrichment effects of human development and commerce which

impede the biota and beneficial uses of that waterbody. 

3) Nutrient Criteria and Standards Development. 

Upon completion of all the waterbody-type guidance documents, EPA expects all States and

Tribes to adopt and implement numerical nutrient criteria into their water quality standards within

three years of publication of waterbody type guidance documents and to complete adoption of

nutrient criteria for all waterbodies in the State by no later than December 31, 2003. EPA expects

States and Tribes to accomplish this by developing their own regional values in watersheds where

applicable data are available, or by using the EPA target nutrient ranges. EPA expects States and

Tribes to select a single value within the range as their water quality criterion where data is

sufficient.

With regard to criteria and standards development, State and Tribes can choose to use the

following approaches:

- The EPA target ranges, or values within those ranges, can be directly adopted 

 by the States or Tribes as their criteria and standards and used to interpret narrative 

standards.

- The States or Tribes can use the EPA target ranges together with their own 
10

databases to develop their own criteria or to evaluate the protectiveness of any 

numerical nutrient criteria they may already have.

- States or Tribes may elect to use the EPA methodology described in waterbody-type

guidance to develop criteria or employ their own approach, independent of the ranges,

as long as it is scientifically defensible.

Once submitted to EPA, the Agency will review the new or revised standards under Section

303(c)(3) of the Clean Water Act. If EPA disapproves the new standard submitted by a State

or Tribe (e.g., because EPA determines that it is not scientifically defensible), or if EPA

determines that a new or revised nutrients standard is necessary for a State or Tribe (e.g.,

because EPA determines that the State or Tribe has not demonstrated reasonable progress

toward developing numerical nutrient standards), EPA will initiate rulemaking to promulgate

nutrient criteria values appropriate to the region and waterbody types. Any resulting water

quality standard would apply until the State or Tribe adopts and EPA approves a revised

standard. In the event EPA promulgates nutrient water quality standards for a State or Tribe,

EPA would likely use the point in the range of greatest confidence (i.e., central tendency). 

When reviewing the adequacy of State/Tribe derived criteria and or ascertaining whether a

State or Tribe is making reasonable progress toward developing an adequate nutrient criterion

and standard, EPA is likely to use the target ranges. 

When the initial target ranges have been established and the States or Tribes have begun the

criteria and standard development process, EPA through the Regional Nutrient Coordinators

will also provide technical and financial assistance for nutrient management planning and

application. This will be through guidance manuals and the services of regional and national 

specialists associated with the Team, as well as financial assistance also administrated by these

Regional Nutrient Coordinators. 

4) Nutrient Teams. 

EPA Headquarters and Regional staff will work closely with State officials and other

interested parties in the development of the nutrient criteria. The overall national nutrient

criteria project will be managed by a National Nutrient Team. The EPA National Nutrient

Team will include Office of Water staff, a Coordinator from each EPA Region, State/Tribal

representatives, and representatives of other Federal agencies (See Figures 2 and 3). EPA will

provide guidance and support to States/Tribes in the form of technical and financial assistance

to help establish their regional programs. 

In addition, each Regional Office will select a Regional Nutrient Coordinator and will establish

a Regional Nutrient Team. The Regional Coordinator will promote the development and

implementation of State and Tribal projects, databases, and nutrient criteria and standards, as

well as manage the award of financial assistance to support this endeavor. Specifically,

Regional Coordinators will have a large role facilitating the collection of nutrient data from

States and Tribes within their Regions. Ultimately, the Regional Coordinators and National

Team will work together to develop nutrient ranges for each ecoregion wherever appropriate

data is available. 
11

FIG. 2

National Nutrient Team

EPA HQ Offices (OW, ORD)

10 Regional Coordinators

3-5 States

Other Federal Agencies (USGS, NOAA, USDA, et. al.)

Function:

 Establish ecoregion maps for nutrients

 Establish best process for collecting data from all sources

 Establish best process for analyzing data and developing 

 nutrient criteria (minimum data and statistics)

FIG. 3

Regional Nutrient Team

1 Regional Nutrient Coordinator

1 HQ Representative

1 State Representative from each State in the Region

Other Federal/State/Local Representatives as needed

Function:

 Collect and analyze regional nutrient data

 Establish nutrient ranges (criteria)

 Award assistance grants to State/Academia where gaps exist 

 in our knowledge
12

Ten Regional Nutrient Coordinators, one from each Region, have been selected and they have 

begun the process of forming their Regional Nutrient Teams. Regional Teams will likely

include representatives from each State in the Region and other federal, State, local

representatives, as needed (including water quality managers, NPDES permit writers, field

biologists, monitoring and modeling experts). For example, a regional team could include

other Regional EPA specialists such as those in Regional and ORD laboratories, as well as

specialists from such agencies as the U.S. Geological Survey (USGS); NOAA– National

Marine Fisheries Service (NOAA-NMFS); the U.S. Department of Agriculture-Natural

Resources Conservation Service and Cooperative State Research, Education, and Extension

Service (USDA– NRCS and CSREES); the U.S. Forest Service (USFS); and the USFWS. 

State/Tribal counterparts of these agencies and States and Tribes regulatory specialists should

also be included. University specialists should be considered, as well as the local communities

and environmental and special interest groups. While this list of participants might be the

ideal, in reality local circumstances will probably dictate a smaller group whose composition is

likely to change with time and needs. However, the agency and community resources

described above should, at the very least, be consulted for information and historical

perspectives on the waters in question.

As technical guidance and assistance is established in the various States and Tribes, periodic

meetings of the Regional Nutrient Team Coordinators should be held to compare experiences,

including successes and failures of approaches taken and techniques tried. Key participants, in

addition to the Coordinators, should be the specialists and natural resource managers (as

described above) who conducted the work so detailed question-and-answer sessions can be

held. A proceedings document for each of these meetings should be prepared and circulated

among the States and Tribes and agencies promptly so nutrient measurement and management

information can be rapidly disseminated.

Following organizational meetings at which the objectives of the program are established, the

business of obtaining State and Tribal cooperation in providing nutrient and other enrichment

indicator data must be addressed. This is best accomplished by indicating the positive

consequences of the information exchange. A trial watershed project, in which the

information is actually applied to help solve an overenrichment problem significant to the

State/Tribe, is an appropriate way to start. This demonstration project can be initiated in

tandem with the overall data-gathering effort and will serve as an incentive to other

States/Tribes to become involved. 

5) Management and Evaluation. 

While the primary focus of this Strategy is to develop regional nutrient criteria guidance, it is

essential to understand the role criteria and standards play in overall nutrient management. 

The management of nutrient overenrichment is not just the development of nutrient criteria

and the application of standards; it is a management process which must integrate a number of

programs and methods including but not limited to: Nonpoint and Watershed programs;

NPDES Permitting program; Biosolids Management program.
13

These various programs offer many options for the resource manager to consider and there

are many new programs still being developed. However, there are some fundamental

management concepts that should apply in most of these situations. Presented below are ten

sequential elements to consider. 

This comprehensive approach incorporates all of the key elements essential to good

management planning, but the user might find that some steps can be consolidated or that

circumstances necessitate a different sequence in the chronology.

1. Problem identification

Make sure a problem exists and is clearly defined in terms that make it possible to seek

a solution.

2. Background investigation

Use literature searches, questionnaires, interviews, and other background

investigations to better describe the problem and determine the information available

about it.

3. Data gathering

Conduct an assessment of water quality including physical, chemical, and biological

parameters and related loading sources in the watersheds. This step should usually be

of one or more years’ duration to accommodate seasonal and annual variation.

4. Identification of key problem areas

Conduct a thorough assessment of all of the above information.

5. Alternative management options

Evaluate each possibility and its impact on present uses with respect to scientific

validity, cost-effectiveness, and sociopolitical feasibility. Involve local and States and

Tribal governments, property owners, citizen groups, and public and business interests

in discussions about the optimal approach. 

6. Detailed management plan

Prepare a plan that discusses how to address each key element of the nutrient problem

in the most effective sequence. Include a stepwise sequence of coordinated activities

in detail. Usually such a management plan is of a maximum 5-year duration. Such a

duration accommodates sufficient measurement and seasonal variation but is short

enough in planning scope to be included in most budget systems. Longer projects

might require sequential management plans.

7. Implementation and communication

Initiate the management program, including adoption of nutrient water quality criteria

and standards and, where appropriate, establishment of nutrients limitations in NPDES

permits and development of TMDLs as elements of the program. Maintain

community, interest group, and other agency involvement through regular updates on

the process. This communication may begin earlier, e.g., at step 4 or sooner, but it
14

should be emphasized here.

8. Monitoring and periodic review

Incorporate water quality monitoring before, during, and after the project to

demonstrate relative response of the system to management efforts. Build in specific

intervals for management review to allow response to changing circumstances;

modifications of methods and schedules; and changes in emphasis as needed.

9. Completion and evaluation

Has the water resource been protected or improved? Give credit to the community

and other participants. Report on successes and failures for future applications and on

lessons learned.

10. Continue monitoring and maintenance

Water resource monitoring stations and parameters should continue on a reduced

scale. Ensure regular maintenance of management efforts to preserve the effects

achieved. Monitoring provides warning of any future degradation, so, if necessary,

resource managers can intervene in a timely, cost-effective manner. Close the cycle by

returning to step 1 for next generation response.

With a good database predicated on reliable indicators and the development of regional

nutrient criteria guidance, States, Tribes, and other jurisdictions will be capable not only of

assessing the trophic status of their waters, but also should be able to establish their criteria

and plan, prioritize, and evaluate their management responses. In doing so, all five strategy

objectives are interrelated at the regional level where problem recognition and remediation are

most effective.

B. How the Elements are Integrated

This national Strategy consists of a regional, waterbody-type approach which permits the

variability in natural nutrient loadings to waterbodies around the country to be recognized,

and criteria to be established which account for this variability. The criteria so developed will

also be waterbody-type specific because different waterbodies respond differently to nutrient

loadings. Also, in recognition of this discrete, but interrelated enrichment process, the finally

developed criteria must limit not only the unacceptable enrichment of a given waterbody or

watercourse, but also must factor in the effects of that enrichment on downstream receiving

waters. 

The waterbody-type technical guidance manuals being developed will provide specific

guidance to the States and Tribes for making the necessary measurements and for developing

the criteria from those measurements, including the establishment of regional target values as

guidelines. These manuals (including wetlands) are scheduled to be completed by the end of

2001. Each technical guidance manual will include ecoregional target ranges. If there is

sufficient data within each of the 14 ecoregions available to develop a nutrient range within

each of the ecoregions for the four waterbody types, 56 nutrient range appendices will be

developed by the end of 2000. If sufficient nutrient data is not available or is insufficient to
15

develop an acceptable peer reviewed nutrient range, EPA will continue to promote data

development in these ecoregions after publication of guidance. 

Once the nutrient guidance and ecoregional ranges are completed it is expected that

States/Tribes will develop nutrient criteria (see Figure 4). 

The implementation of the criteria will be supported by the regional nutrient teams by

providing technical and logistical expertise as well as funding assistance. The criteria can then

be used in management planning and evaluation on a watershed basis with community

involvement so the ultimate objective of enhancing and protecting our nations water resources

is achieved.

III. WATERBODY-TYPE TECHNICAL GUIDANCE.

Waterbody-type guidance manuals will provide the standardized methods available to the

States/Tribes and other jurisdictions to promote the development of consistent regional

databases that reflect conditions in each part of the country. This is important because

overenrichment and natural levels of enrichment differ from one geographic area to another, in

part because of differing cultural, geologic, and climatologic influences. These factors change

the ambient background from one region to another and necessitate a regional approach to

these measurements and to the nutrient criteria to be developed. 

A key element of each waterbody-type guidance manual is the recommended list of reliable

indicators of overenrichment, how they might best be measured, and how and when to collect

the necessary samples for this measurement. (These manuals may also include sections

addressing the remaining objectives of this strategy, i.e., data storage and assessment, research

needs, and best management practices for nutrient impact mitigation.) EPA intends that the

publication of these technical guidance documents will help standardize assessments and

promote regional interstate cooperation for nutrient control. 

The following is a partial listing of overenrichment indicators, data requirements, management

options, and research needs recommended by the component nutrient workgroups at the

December 1995 meeting in Washington DC, and by subsequent reviewers. Some of these

recommendations are qualitative in nature; such indicators are also valuable and definitive in

their own right. All of the indicators are meant to serve as a starting point for enrichment

assessments, which are expected to be expanded and refined into more quantitative

evaluations as the guidance is further developed and as individual States/Tribes make regional

adjustments to the methods. 

Even as a partial listing, this material may seem remarkably detailed to the general reader for a

strategy document. It must be recognized that this strategy is predicated upon the proper
14 ECOREGION

NUTRIENT CRITERIA

RANGES APPENDED TO

WATERBODY GUIDANCE

DOCUMENT

NATIONAL NUTRIENT STRATEGY

LAKES AND

RESERVOIRS

GUIDANCE

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RIVERS AND

STREAMS

GUIDANCE

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ESTUARINE

AND COASTAL

GUIDANCE

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WETLANDS

GUIDANCE

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STATE/TRIBAL IMPLEMENTATION OF GUIDANCE AND CRITERIA

PROMULGATION IF STATES/TRIBES TAKE NO ACTION TO

DEVELOP NUMERICAL NUTRIENT WATER QUALITY STANDARDS

16

 Figure 4
17

measurement of valid environmental indicators for the establishment of scientifically defensible

nutrient criteria. The identification of the premises upon which these criteria are based is

essential to a fair and objective review of this strategy by the public.

A. INDICATORS

The indicators (parameters) listed below are the initial candidates for inclusion in the guidance

documents. Each EPA technical guidance drafting committee will make final

recommendations as they further explore the scientific veracity and practicality of the material. 

Additionally, each document will include recommendations for the most appropriate sampling

and analytical techniques.

LAKES AND RESERVOIRS

A focus of this guidance will be to establish the connection between lake nutrient

environmental impacts to public health concerns, e.g., septic and sewage effluent discharges. 

This twofold approach relating environmental degradation to potential public health risks (as

well as recreational uses and biodiversity concerns) should further stimulate public support of

these initiatives. An outline of this proposed guidance document is attached as Appendix C.

The guidance will include and emphasize watershed-scale assessments and management

approaches, illustrated by case histories and demonstration projects.

Surveys should address both spatial and temporal variability, including seasonality and in some

instances variation over the course of a day. Whenever possible, year-round sampling is

advisable. For in-lake surveys, it is presumed that the investigator will design for optimal

spatial and bathymetric placement of the stations for that waterbody and that these data will

be compared to reference lakes in that classification. Some of the parameters or indicators to

consider follow: 

C Early Warning Watershed Indicators

— Land use/loading assessments and changes in watersheds (geographic information

systems (GIS) are effective tools for evaluating nutrient loadings as a function of

land use at a variety of scales). In areas of the country where agriculture and/or

animal feeding operations exist, it is imperative to identify and assess these

locations of potential sources of nutrients by collecting data on size and location of

farms/animal feeding operations within a given watershed.

— Changes in hydrologic regimes

C Chemical/Biomass Parameters

— Phosphorus (P) concentration (total P (TP) and total dissolved P in hypolimnion )

— Nitrogen (N) Concentration (total KN, NO as N, NO as N, and NH as N, e.g., 2 3 4

total N (TN), also N:P ratios)

— Chlorophyll (total or chlorophyll a)
18

— Secchi disk depth (m)

— DO (hypolimnetic)

C Community Structure Parameters

— Algal community (composition and biomass)

— Macroinvertebrate structure (composition and biomass)

— Fish (composition and biomass)

— Macrophytes (composition and biomass)

C Secondary Parameters

— Total suspended solids (TSS)

— Total organic carbon (TOC)

C Indicators for Immediate Assessment

— Preliminary survey data in addition to early warning land use information: TP, total

chlorophyll, Secchi depth and DO. These should have established validity, low

cost, and they should be readily used in prediction and modeling.

A historical perspective might be helpful to the data assessment process by integrating

paleolimnological surveys with an evaluation of land use practices and changes. 

STREAMS AND RIVERS

It is useful, for assessment purposes, to separate streams and rivers into two categories with

optimal reference systems: for plankton-dominated systems and periphyton-dominated

systems. The major differentiating characteristic between these two systems is that nutrients

saturate the biomass at a much lower level in the periphyton-dominated systems than they do

in the plankton-dominated systems. Summarized below are potential nutrient indicators for

the plankton- dominated and periphyton-dominated systems. Early warning indicators of

potential excess nutrient loadings may be significant shifts in land use patterns or in

climatological events or other activities contributing to extreme runoff.

The indicators that follow are not presented in any order of sensitivity or utility. 

C Plankton-dominated Systems C Periphyton-dominated Systems

— Algal biomass — Algal biomass (mg/m percent 2

coverage)

— Transparency — Transparency 

— TN — TN, dissolved inorganic nitrogen

(DIN)

C Appropriate to Either Plankton or Periphyton-dominated Systems
19

— pH (maximum and diel) — Sediment composition

(physical/chemical)

— DO (minimum and diel) — Ratios of summer/winter nutrient

concentration

— Ash Free Dry Weight (AFDW)/ — Ratios of dissolved/total nutrient

Chlorophyll a concentrations

— Aesthetics (foam, scum) — Temperature

— Benthic community metabolism — TSS, volatile to suspended solids 

ratio

— Secondary production (meiofauna, — Biointegrity (macroinvertebrate 

index macroinvertebrates, fish) community composition)

— Hydrologic characteristics — Production/respiration

— TP, soluble reactive — Dissolved organic material

phosphorus (SRP) — Relative plankton composition of 

Cyanophyta and dinoflagellates

ESTUARIES AND COASTAL MARINE WATERS

Estuaries and coastal marine systems can be subclassified for assessment according to the

dominant vegetation type, as was done by the Estuaries Workgroup during the 1995

workshop. However, other systems of classification, such as classification by physical

characteristics, can also be used. The participants in the December 1995 workshop selected

the following categories: seagrass-dominated, plankton-dominated, and macroalgaedominated (as indicated below). The indicators associated with these categories can be

applied to either short-term or long-term assessments. It should also be noted that there are

physical, chemical, and biological indicators other than those listed below (such as fish kills,

suspended material, nutrient concentrations, toxins, and benthic invertebrate communities). 

Early warning indicators of potential excess nutrient loadings might be significant shifts in land

use patterns or in climatological events or other activities contributing to extreme runoff. All

indicator measurements in these waters must be qualified by attention to tide cycles, density

and salinity gradients, and currents when they were made.

C Seagrass-dominated Systems

— Areal surveys of distribution, abundance, and depth of grasses

— Waterbody-type light requirements (seagrass depth vs. light attenuation)

— C:N:P ratios in plant leaves

— Leaf chlorophyll a

— Quantum irradience levels

— Chlorophyll a-to-b ratios

— Transparency

C Plankton-dominated Systems

— Chlorophyll a

— Algae such as cyanophyta, dinoflagellate, and diatom assemblages including HABs;

documentation of the incidence and location of blooms

— DO determinations that consider cyclic fluctuations and distinguish between natural
20

and anthropogenic causes

— The role of silica relative to nitrogen and phosphorus in phytoplankton blooms

— Macroinvertebrate and other consumer community changes

C Macroalgae-dominated Systems

— Macroalgae influence on DO concentrations, dissolved organic carbon concentrations,

and lower trophic levels.

WETLANDS

Methods for assessing nutrient impacts to wetlands are perhaps less established and

standardized than those for the other waterbody types. This is due to the variability within

wetland types (e.g., bogs, swamps, etc.) and the lack of historic databases in these areas. 

Some methods developed for lakes and rivers are applicable to wetlands with standing water,

but there are few methods appropriate for wetlands that have saturated soils or are

infrequently flooded. Surveys of wetlands should address both the spatial and temporal

variability in nutrient levels, including seasonal and diel variation. Surveys should also address

the variation in nutrient levels both within a wetland and between different wetland types. 

Some wetlands are often naturally eutrophic and will respond to nutrient additions much

differently than bogs and other oligotrophic wetlands. The variability in plant communities

(i.e., succession) will also affect how a wetland assimilates nutrients.

The following are suggested methods for assessing the effects of nutrients in wetland habitats. 

However, for most of these parameters, few baseline data are available with which to compare

collected data.

C Early Warning Watershed Indicators

— Land use/loading assessments and changes in watersheds

— Precipitation, in-flow, runoff, and any extreme climatological or anthropogenic events

C Chemical/Biomass Parameters

— Phosphorus concentration (total)

— Nitrogen concentration (total, also N:P ratios)

— Chlorophyll (total or chlorophyll a)

— Secchi disk depth (m) (for wetlands with standing water)

— DO and soil oxygen demand

C Biological Assemblage Parameters (e.g., composition, richness, diversity, and indicator 

 species)

— Attached microbial community

— Algae such as dinoflagellates and diatoms

— Macrophytes including emergent vegetation

— Macroinvertebrates

— Fish (for wetlands with standing water)

C Secondary Parameters
21

— TSS

— TOC

Since wetlands differ in their capacity to assimilate nutrients, it might be difficult to evaluate

whether a given nutrient load will have a significant ecological impact on a wetland. 

Biological monitoring is useful to assess the response of wetland plants and animal

assemblages to overenrichment and to detect degraded habitats. Microbial, macrophyte

communities and algae, such as dinoflagellate and diatom assemblages, are particularly useful

for detecting nutrient impacts by measuring their diversity, richness, composition, and

structure. These assemblages can be compared to the assemblages found in reference

wetlands that range from “minimally disturbed” to severely impacted by nutrient enrichment. 

Thus, the biological integrity of a wetland can be determined relative to the biologic

assemblages present in the reference wetlands. The macroinvertebrate, fish, and plant

assemblages can also reflect direct impacts of overenrichment and indirect impacts such as

reduced levels of dissolved oxygen. 

Another method of monitoring wetlands is to identify the accumulation of organic material

over time as an indication of a change in productivity. This can be done by placing pieces of

feldspar within wetlands and monitoring them for accumulation. Feldspar does not react with

other chemicals in the soil and, therefore, could be used as a benchmark for measuring the

buildup of organic material. 

There are two systems of wetland classification that might be useful for selecting and

comparing wetlands. Cowardin et al. (1979) developed a hierarchical system of wetland

classification based largely on the structure of the plant community (e.g., forested,

scrub/shrub, emergent, etc.). In addition, Brinson (1993) developed a hydrogeomorphic

(HGM) framework for classifying wetlands based on a wetland’s landscape position, source of

water, and hydrodynamics.

B. DATA STORAGE AND PROCESSING 

Once a standardized methodology for data gathering is available, the States and Tribes will

also need a consistent and mutually compatible data storage, retrieval, and assessment system

to help them interpret data and convert them to meaningful management information. An

element of each waterbody-type guidance document should be convenient desktop, PC-based

data storage and modeling programs. Such programs will not only enhance data assessment,

but will, if consistent throughout a region, promote coordinated interstate surveys and data

sharing. Many States already have sufficient nutrient databases and such data storage systems

should be established in consultation with all potential partners. In fact, as Regions develop

this aspect of the strategy, it is imperative that they consult with the States/Tribes to establish

what systems are most efficient, cost-effective, and appropriate for data sharing without

violating resource management confidentiality. EPA is currently engaged in determining the

future design of a nationwide database, and this strategy should be compatible with that effort. 

Ensuring compatibility would include standardization of both data storage systems and

models. The success of multi-State cooperation and coordination of monitoring activities will

depend on this.
22

In all cases it will be essential that the quality of the data entered into these databases be

carefully documented. Documentation should include information on methods used, minimum

detection limits, and comparison to standards. Modelers should use due caution if quality

assurance aspects of the data are not available.

Once such a database system is in place, calibrated and verified models can be developed or

applied to help predict the likely consequences of management actions or, just as important,

the lack thereof. Listed below are suggested needs or available resources appropriate to each

waterbody type.

LAKES AND RESERVOIRS

Modeling:

Modeling is ideal in many ways for lake assessments. The BATHTUB and Reckhow-Simpson

technique are two of many examples of existing lake models used by managers to predict

trophic responses to estimating nutrient loading adjustments. The BATHTUB applies a series

of empirical eutrophication models to morphologically complex lakes and reservoirs. The

program performs steady-state water and nutrient balance calculations in a spatially segmented

hydraulic network that accounts for advective and diffusive transport, and nutrient

sedimentation. (For details, see National Nutrient Assessment Workshop Proceedings, EPA

822-R-96-004, July 1996.) 

The goal of this strategy is to provide simple, user-friendly, desktop-based software models

for States and Tribes and local governments to aid them in waterbody management decision

making. Impoundments/reservoirs often have unique hydrographic profiles and therefore will

probably require models calibrated specifically for use with these waterbodies.

STREAMS AND RIVERS

Modeling:

It is necessary to identify ways to improve on the existing models to examine the

interrelationships and links between nutrient sources and nutrient impacts and help to tailor

these models to both plankton- and periphyton-dominated systems. Participants at the

December 1995 workshop noted in particular that modeling tools are lacking for periphytondominated systems, including both simple mass balance or regression relationships and

complex process-based models. Below are ways to improve on the existing models’

capabilities. For more details on any of the models listed below, see the National Nutrient

Assessment Workshop Proceedings (EPA 822-R-96-004, July 1996).

C Provide land use connections in watershed-scale models.

C Conduct sensitivity analyses.

C Conduct carbon-based simulations.
23

C Add temperature simulation to the WASP5 model. WASP5 is widely used in both water 

quality assessment and toxic modeling. The model considers comprehensive dissolved 

oxygen and algal processes, but does not include the carbon and silica cycles or full

sediment diagenesis model. In addition, its use is limited because it does not account for 

temperature. Therefore, adding temperature simulation to WASP5 would allow for

diurnal temperature variations.

C Add periphyton to the QUAL2E, WASP5, and HSPF models. QUAL2E and HSPF are 

models that capture the longitudinal transport that dominates in most rivers and streams. 

QUAL2E and HSPF both consider advection and dispersion. Adding periphyton to these

models would allow for simulation of periphyton biomass in the riverine system.

C Introduce load/response relationship (plankton) and concentration/response relationship

(periphyton) to pinpoint where nutrient loading reduction can be targeted.

C Develop desktop models that are easily transferred across waterbodies and use the

following parameters: TP, TN, total chlorophyll, DO, temperature and transparency

(Secchi disk and black disk).

ESTUARIES AND COASTAL MARINE WATERS

Modeling:

Estuarine and coastal marine models are in the process of development and testing around the

country, including efforts on the Chesapeake Bay. Much of this work is promising, and the

following are areas requiring further effort.

C Seagrass-dominated Systems

— Develop water quality models, from simple to complex, that look at simulation of

chlorophyll a concentrations over seagrass beds from nutrient loadings of the

surrounding watershed.

— Develop multiple regression analysis models that simultaneously consider such factors

as TSS, color, and chlorophyll a.

C Plankton-dominated Systems

— There is a need for an estuarine version of “Vollenweider” relationships to better

understand the relation of nutrient loadings to chlorophyll a.

C Macroalgae-dominated Systems

— Many databases exist that would allow identification of nutrient loading thresholds for

macroalgae-dominated systems.
24

WETLANDS

Modeling:

Very few models exist that are capable of predicting wetland responses to nutrient loadings. 

Of the literature reviewed, Mitsch and Gosselink (1993) and Howard-Williams (1985) offer

conceptual diagrams of potential relationships for nutrients in wetlands. Wetlands can

function as a source, sink, or transformer for a particular nutrient. A wetland is considered a

sink if it has a net accumulation of a nutrient. In contrast, a wetland is considered a source if

it exports more of a nutrient than it accumulates. A wetland is a transformer if it transforms a

chemical from one form to another, such as from dissolved to particulate form, but does not

change the amount going into or out of the wetland (Mitsch and Gosselink, 1993). In some

cases, a wetland can be a sink for one nutrient while it is simultaneously a source for another

nutrient.

Nutrient models for wetlands, as for all waterbodies, should account for atmospheric, surface,

and subsurface inflows and outflows. The models should account for gaseous, aqueous, solid,

and sediment-attached forms of the nutrients. The models should also account for the uptake

and release of nutrients by living biomass and by decomposition of biomass. In addition, the

models should address the seasonal and daily patterns of nutrient uptake and release by plants

and animals. Chemical transformations based on changes in pH and concentrations of other

chemicals should also be considered. All models should be validated on reference wetlands.

Sediment loading models used to predict TMDL loading rates from storm events can be useful

for estimating phosphorus inputs. Some traditional water quality models, such as CEQUALW2 and WASP5, have been used for evaluating wetlands. Hydrodynamic models, such as

EFDC, are being applied to wetlands in Florida to assess hydrologic response. Analysis of

wetlands may also include the assessment of inputs/loadings using a variety of loading models

(e.g., SWMM, HSPF) that can be used to predict nutrient and sediment loads to local

wetlands (USEPA 1992). Further model development is needed, particularly for wetlands

that have saturated soils and are infrequently flooded.

C. MANAGEMENT AND EVALUATION

The material in this section is not intended to be an all-inclusive list of remediation, protection,

and management approaches. However, it is an introductory presentation of some of the

readily evident options States and Tribes and other responsible parties can use to make a

positive response to the nutrient information they obtain and the water quality criteria States

and Tribes develop. 

Options also exist that might not be specific to waterbody-type, such as the watershed

approach. This approach allows communities to focus resources on a watershed’s most

serious nutrient sources, which might include animal waste and excess fertilizer runoff. 

Additional basic management measures can be found in other EPA documents such as

Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal

Waters (EPA 840-B-92-002). The following, as well as additional approaches (such as the
25

development of TMDLs for nutrient-impacted waters, the control of animal waste discharges,

and the control of outbreaks of Pfiesteria and similar harmful algal blooms), will be explored

further in the guidance materials to be developed as part of this strategy.

MANAGEMENT

In considering the various management options, the resource manager should also keep in

mind that the different waterbody types described here may often be interrelated, e.g., streams

draining to and from lakes, and rivers entering estuaries and coastal waters. Under these

circumstances, the manager should be careful to select for a management plan practices that

do not have negative downstream effects. For example, it might not be appropriate to raise a

lake level to the detriment of riparian wetlands and influent streams.

LAKES AND RESERVOIRS

Examples of management options to consider when dealing with lakes and reservoirs are

provided below. 

C Vegetative buffer zones— Preserve or reestablish natural, indigenous vegetation (ground

cover, shrubs, trees) in the riparian zone to intercept sediment and nutrient runoff before

the runoff reaches the waterbody.

C Watershed land use changes— Identify critical loading sources and promote changes of 

these land use practices. Examples of practices to promote are implementation of

conservation farming; use of manure holding facilities; use of road, commercial, and

municipal runoff diversions and detentions; restoration of woodlots in critical drainage

areas; land use planning to avoid excessive tiers of lake residences; and on-site septic

system use and improvement.

C Habitat restoration— Improve lake nursery and spawning areas to restore a diverse

aquatic community and food chain.

C Fish stocking and removal— Perform adjustment of fish communities disrupted by

overenrichment by the selective removal of undesired species, the addition of more

preferred species.

C Water column precipitation and sediment sealing techniques— Apply alum to the water

column to remove P and to seal nutrients into bottom sediments under precipitate.

C Macrophyte harvesting and flow regulation— Perform weed control by use of mechanical

harvesters to enhance lake use of nutrients and to remove some nutrients present in

biomass. Initiate winter or other episodic drawdowns of lake/reservoir waters to augment

sediment removal or consolidation. 

C Biomanipulations— Ensure balanced predator stocking or grazer support to control bluegreen algae and other nuisance primary producers.
26

C Relocation of sewage outfalls— Move sewage outfalls to locations that will minimize

deleterious impacts to the waterbody.

C Restoration and protection of strategic wetlands— Restore and protect wetlands located

in areas critical to water quality concerns.

C Hypolimnetic aeration— Implement techniques designed to aerate the hypolimnion.

C Point source nutrient removal— Remove nutrients at point sources using techniques such

as tertiary treatment and phosphorus precipitation.

C Storm water management— Implement storm water BMPs such as constructing ponds,

wetlands, infiltration and detention basins, and diversions.

STREAMS AND RIVERS

Issues and actions to consider associated with the abatement of nutrients in streams and rivers

include:

C Land use— Include land use as a separate early warning indicator (i.e., if development is

proposed in a watershed, an environmental impact study should be done to assess the

potential impact of such development on the surrounding waterbody).

C Designated use and biomass relationships— Employ public survey techniques to monitor

relationships between designated uses and algal biomass.

C Seasonal relationships— Investigate seasonal relationships between nutrients and biomass

across streams.

C Nitrogen-phosphorus cycling— Enhance nitrogen-phosphorus cycling on different land

uses to reduce mobilization (septic, forest systems).

C Riparian zone management— Introduce riparian buffers, shade the streams, or perform

canopy restoration to minimize direct sunlight on surface water. Shading can also reduce

the amount of direct air deposition of nitrogen and other nutrient sources.

C Channel restoration— Minimize the nutrient loadings by constructing channels to help 

reduce the rapid nutrient flush from one segment of the waterbody to another.

C Biological controls— Introduce biomass eating organisms such as caddis fly larvae 

(Dicomoecus gilvipes), which efficiently remove both periphytic diatoms and filamentous

algae from rock substrata.

C Hydrology, hydraulics (flow regime, storm water management, stream regulation)—

Identify natural hydrologic regimes and use such information in addressing dam operations

to better replicate natural conditions in the area while generating power or preserving
27

intended reservoir levels. 

C Impoundment removal— Remove man-made impoundments that have lost their utility and

are now causes of flow interruption and sources of excessive algae and water quality

degradation.

C Restoration of riparian and floodplain wetlands— Implement programs designed to restore

riparian and floodplain wetlands. 

C Point source nutrient removal— Remove nutrients at point sources using techniques such

as tertiary treatment and phosphorus precipitation.

C Storm water management— Implement storm water BMPs such as constructing ponds,

wetlands, infiltration and detention basins, and diversions.

ESTUARIES AND COASTAL MARINE WATERS

The following are basic management options to consider for all vegetation system types:

C Land use and development controls— Promote natural vegetative cover in shore areas and

zoning restrictions on dense residential or commercial/industrial development along

shoreline areas.

C Discharge and dumping regulation and marine sanitation devices— Encourage enhanced

Publicly Owned Treatment Works (POTW) design and operation, and the diversion of

POTW effluent from sensitive or poorly circulated waters. Promote and enforce marine

sanitation device (MSD) regulations including providing adequate pumpout services.

C Restricted estuarine/coastal areas— Protect sensitive waters such as endangered 

shellfish beds, spawning and nursery areas, and recovering weed beds. 

C Shoreline erosion controls— Implement erosion controls on banks subject to wave or ice

damage. Restrict access to sensitive shorelines, dune restoration areas, and shorelines

susceptible to erosion. 

C Seagrass replenishment— Restore weedbeds in estuaries, including wetland areas. Plant

and protect emergents and terrestrial riparian vegetation as further protection of tidal zone

wetlands from runoff.

WETLANDS

Best management options to consider for wetlands include: 

C Wetland protection and restoration— Preserve and restore wetlands through the

implementation of voluntary and regulatory programs.
28

C Vegetative buffer zones— Preserve or reestablish natural, indigenous vegetation (ground

cover, shrubs, trees) as buffer zones adjacent to wetlands to intercept sediment and

nutrient runoff before the runoff reaches the wetland.

C Watershed land use changes— Identify critical land loading sources and promote changes

of these land practices. Examples of changes that could be made include the

implementation of conservation farming techniques; the reduction of the use of fertilizers

on farms and lawns; the construction of manure holding facilities, runoff diversions and

detentions, filter strips, and vegetated drainage ways; the implementation of forestry

BMPs; the implementation of controls on urbanization and industrial development; and the

upgrading of on-site and municipal wastewater treatment systems.

C Land use planning— Protect wetlands by limiting amounts of impervious surfaces, limiting

development near waterbodies or steep slopes, and minimizing discharges from storm

water, sewer, and septic systems.

C Protect and restore streams entering wetland— Stabilize stream channels and establish

riparian buffers to reduce the amount of sediment-attached nutrients entering a wetland.

EVALUATION

Once the appropriate parameters or indicators have been established, EPA and the States or

Tribes will be able to evaluate the effectiveness of the management and regulatory approaches

taken. The databases and monitoring systems developed, together with the derived criteria,

should be used to assess actual management progress toward ameliorating overenrichment

conditions. (This process will be described in detail in each waterbody type specific technical

guidance manual.) Where methods and techniques have been successfully employed, the

experience may be applied to similar circumstances elsewhere. Where success has not been

achieved, the knowledge gained is valuable in developing alternative approaches and in

avoiding making the same mistake again. This information should be shared among the

Regional Nutrient Teams, through correspondence and national meetings, to enhance

management effectiveness. 

Periodic program progress reports and budget statements will be prepared for the Office of

Water, based on the proceedings described immediately above, so continuity of the program

can be maintained, funding and other administrative support provided, and new needs

identified and addressed.

The sum total of these reports and proceedings of the periodic national team meetings will

provide the necessary feedback to EPA Headquarters to help further development and

shaping of national policy with respect to nutrient management of the Nation’s waters.

D. RESEARCH NEEDS
29

For all four major waterbody types, there are a number of research needs that should be

addressed. A number of these research needs are noted below. They are highlighted to

indicate areas which each technical guidance drafting group should address to attempt to

reduce uncertainty in the assessment process.

LAKES AND RESERVOIRS

C Phosphorus and nitrogen speciation investigations.

C Sedimentation and nutrient load impacts on trophic states.

C Internal loading and recycling of nutrients regarding biological responses.

C Biomanipulation techniques.

C Better understanding of cascading trophic interactions, i.e., the effects of nutrient changes

on one level of the food chain and how the rest of the community is affected. 

STREAMS AND RIVERS

C Chlorophyll measurements (periphyton).

— Sampling methods

C Cladophora, diatom, and blue-green alga growth requirements.

— Field research

C Literature search on stream models (periphyton system).

C Stream bank, riparian zone, and denitrification.

C Investigation of dissolved oxygen and pH amplitude.

C Investigation of community metrics to characterize rivers for nutrient effects.

— Ecoregions

— Which metrics are most sensitive?

— Literature search on indicator taxa

— Is biointegrity sensitive as an early warning tool?

C Role of fluvial geomorphology as a factor in controlling algae development.

C Whole stream overenrichment studies.

C Investigation of seasonal relationships between nutrients and biomass across streams.

In addition to identifying the above research needs, the December 1995 workshop participants 

discussed a number of other actions that should be taken to help managers and scientists

assess nutrient impacts on river and stream systems. These actions include the following:

C Conduct literature searches on stream modeling techniques, community metrics, and 

designated use and biomass relationships (e.g., using survey techniques).

C Explore how biological indicators can be used to determine causes of systematic change.

C Explore, on an ecoregional basis, the level at which biomass and chlorophyll a

concentrations begin to impair beneficial uses of rivers and streams.

C Explore causal linkages observed in stream community metrics.

C Explore how the use of various management options, in addition to nutrient controls, will 

help maintain designated uses of river and stream systems (e.g., sediment and erosion 

controls, channel restoration, riparian zone management, etc).

C Involve other organizations in efforts to understand nutrient impacts on river and stream 
30

systems, including volunteer monitoring programs.

ESTUARIES AND COASTAL MARINE WATERS

C Resolution of N-P limiting question with salinity gradients.

C Role of dissolved oxygen in estuarine overenrichment.

C Role of sedimentation-turbidity in overenrichment.

C Biological community indicators.

C Tidal and discharge dynamics in estuarine nutrient flux resources including marine

loadings vs. watershed resources.

C Impact of shore discharges on estuaries and coastal marine overenrichment including

better loading estimation models.

C Models to predict HAB events in eutrophic systems and appropriate response strategy as

described in National Harmful Algal Bloom Research and Monitoring Strategy: an initial

focus on Pfiesteria, fish lesions, fish kills and public health (draft, November 1997).

WETLANDS

C Development of an accepted national wetland classification system similar to the

hydrogeomorphic system developed by the Army Corps of Engineers.

C Development of a nationwide database for natural wetlands like that currently available for

constructed wetlands should be developed. The database should include wetland types

and statistical characteristics that apply to each type. A national database could be used to

compare the measurement parameters of assessed (impacted) wetlands to an established

set of reference conditions.

C Comprehensive literature search to determine what work has already been done on

nutrient-related wetland issues. 

C Development and testing of biological assessment and monitoring methods for detecting

nutrient impacts.

— Which biological assemblages are most sensitive?

— Which metrics are most sensitive?

C Establishment of a regionalized network of wetlands of different types (e.g., bogs, swamp)

across a gradient of nutrient disturbance from “minimally impacted” to degraded.

C Further research on the impacts of nutrients on different wetland types (e.g., bog, marsh,

swamp).

C Further research on influence of land use within watersheds on the impacts of nutrients to

wetlands.

C Field experimentation to determine nutrient limitation to wetland type and to isolate the

effects of nutrients from other variables, such as hydrology, climate, and physical

alteration of habitat. 

C Models for nutrient inflow, export, and transformation within different wetland types.

C Further investigation of how the bioavailability of nutrients is affected by water chemistry

(e.g., pH, dissolved metals) and substrate (e.g., percent clay, percent organic matter).
31
32

APPENDICES
33

Appendix A: Summary of Water Quality Criteria and Standards for Nutrient

Overenrichment 

In 1994, EPA commissioned a study that gathered information on State Water Quality Criteria

and Standards for Nutrients. The following is an abstract of that study. Table 1 is a summary

of water quality criteria and standards for nutrient enrichment listed by State.

Nitrogen

Seventeen States, the District of Columbia, and the Virgin Islands have no specified water

quality criteria for nitrates and/or nitrites. Seven States have only narrative criteria for

nitrogen. Four States have narrative and quantitative criteria. Nine States use only EPArecommended nitrate-nitrogen criteria (10 mg/L) for the protection of domestic drinking

water supplies. Twelve States and Puerto Rico use EPA-recommended criteria in conjunction

with other criteria, either quantitative or narrative. Five States and four U.S. territories have

quantitative water quality criteria for nitrogen but do not incorporate EPA-recommended

criteria into them.

Phosphorus

In the case of phosphorus, 21 States, the District of Columbia, and the Virgin Islands have no

specified water quality criteria. Twelve States have narrative criteria addressing phosphorus

in general. Seven States have both narrative criteria and quantitative criteria addressing

phosphorus. One state, Florida, uses the EPA-recommended phosphorus criterion of 0.10

ug/L for its estuarine and marine waters. Fifteen States and five U.S. territories have

quantitative water quality criteria addressing phosphorus but do not use the EPArecommended numerical criteria.
34

TABLE 1

SUMMARY OF STATES’ EXISTING WATER QUALITY CRITERIA AND STANDARDS 

FOR NUTRIENT OVERENRICHMENT

Region/State Nitrate Ammonia Nitrogen Phosphorus

Total Total 

Region 1

Connecticut T (3)

Maine T (7,3,8)

Massachusetts T (2) T (2) T (2)

New Hampshire T (2)

Rhode Island T (3) T (3) T (3)

Vermont T (2) T (2) T (2)

Region 2

New Jersey T (2) T (2) T (9,3)

New York T (2)

Puerto Rico T (9) T (9) T (8,2)

Virgin Islands T (8,9)

Region 3

Delaware T (2) T (2) T (2)

District of Columbia

Maryland

Pennsylvania

Virginia T (4)

West Virginia

Region 4

Alabama

Florida T (2) T (7,2)

Georgia T (3)

Kentucky T (2)

Mississippi

North Carolina T (3)

South Carolina T (2) T (2) T (3)

Tennessee
TABLE 1

SUMMARY OF STATES’ EXISTING WATER QUALITY CRITERIA AND STANDARDS 

FOR NUTRIENT OVERENRICHMENT

Region/State Nitrate Ammonia Nitrogen Phosphorus

Total Total 

35

Region 5

Illinois T (1) T (1,3,9)

Indiana T (1,2)

Michigan T (2) T (2) T (2)

Minnesota

Ohio T (2,4)

Wisconsin

Region 6

Arkansas T (2) T (2) T (2) T (2)

Louisiana T (2) T (2) T (2)

New Mexico T (2) T (2) T (7,2)

Oklahoma

Texas T (2) T (2) T (2)

Region 7

Iowa

Kansas T (2)

Nebraska

Missouri

Region 8

Colorado

Montana

North Dakota T (2) T (7,2,9)

South Dakota T (2) T (3)

Utah T (2) T (2) T (7,3)

Wyoming

Region 9

American Samoa T(2) T(2) T (1,9) T (1,9)

Arizona T(5) T(5) T (1,2) T (1,2)

California T (1,5) T(5) T(1,2) T (1,6,7)
TABLE 1

SUMMARY OF STATES’ EXISTING WATER QUALITY CRITERIA AND STANDARDS 

FOR NUTRIENT OVERENRICHMENT

Region/State Nitrate Ammonia Nitrogen Phosphorus

Total Total 

36

Guam T (2,7) T(5) T(2) T (2,7)

Hawaii T (1,9) T (1,9) T (1,9) T (1,9)

Nevada T (5) T (2,5) T(1,7,9) T (1,7,9)

Northern Mariana Islands T(7) T (5) T (7) T (7)

Trust Territories of the Pacific T(2) T(2) T (7) T (7,9)

Islands

Region 10

Alaska

Idaho T (2)

Oregon

Washington

NOTES FOR TABLE 1

Blank entry indicates that neither a narrative nor numeric criterion for the nutrient have been specified by the State.

(1) Site-specific numeric values for ambient nutrient levels.

(2) Narrative criteria related to natural conditions, eutrophication and nutrient overenrichment for nitrate, ammonia,

inorganic nitrogen, total nitrogen, or total phosphorus.

(3) Narrative criterion that is not related to natural conditions, eutrophication, or nutrient overenrichment issues.

(4) Numeric values for effluent nutrient levels.

(5) Numeric values related to public health (nitrate) or aquatic toxicity (ammonia).

(6) Habitat-based numeric values for ambient nutrient levels.

(7) Water use classification- or water use designation-based numeric values for ambient nutrient levels.

(8) State wide numeric values for ambient nutrient levels.

(9) Waterbody-based ( streams, rivers, lakes, estuaries, coastal/oceanic waters) numeric values for ambient nutrient

levels.
37

Appendix B: Nutrient Criteria Activities and Timeline

Year Activities Products Date

1997 Publish Final National Nutrient Strategy & FR Notice of 6/98 FR notice

Strategy Availability

1998 Publish Technical Guidance

Document for:

Lakes and Reservoirs Final Guidance 12/98

Demonstrations and Case

Studies:

Initiate 3-5 case studies Methodology validation On-going

and regional criteria for

Lakes and Reservoirs

Outreach Activities &

Communication Strategy:

Regional/State Meetings on Proceedings 10/98

Strategy and Nutrient Criteria 

Development

WQS Academy Presentations Summer,1998

Document availability via Internet Brochures & Fact National

Sheets Nutrient 

Strategy

Link info to Regional Nutrient Training On-going

Teams

1999 Publish Technical Guidance

Documents for:

Rivers and Streams Final Guidance 03/99
Year Activities Products Date

38

1999 Demonstrations and Case

Studies:

Initiate 5-10 case studies Methodology validation On-going

and regional criteria for

Rivers and Streams

Methodology validation On-going

and regional criteria for

Marine Coastal Waters

and Estuaries

Outreach Activities:

Regional/State Meetings on Rivers Proceedings 7/99

& Streams/Lakes Guidance

WQS Academy, Presentations On-going

Document availability via Internet Brochures & Fact Lakes and

Sheets Reservoirs

2000-2 Publish Technical Documents

for:

Coastal Marine Waters and Final guidance 03/00

Estuaries

Wetlands Draft guidance 03/00

Data processing and assessment Final Guidance & 4/00

National Modeling

Database

Demonstrations and Case

Studies:

Maintain ongoing case studies and Regional Criteria 01-02

publish regional criteria Guidance
Year Activities Products Date

39

2000-02 Outreach Activities:

Regional/State Meetings on Coastal Proceedings On-going

Waters and Estuaries Guidance 

WQS Academy

Document availability via Internet Sheets Streams

Presentations On-going

Brochures & Fact Rivers and

Coastal Waters

and Estuaries 

Data processing

and Assessment
40

Appendix C: Draft Outline for the Development of Nutrient Criteria for Streams and

Rivers, Lakes and Reservoirs, and Estuaries and Coastal Marine Waters.

I. Introduction

Concept of Nutrient Criteria

— Regional in nature

— Methods and guidance to support development of nutrient criteria

— Discussion of criteria vs. standards

— Narrative criteria vs. numeric, but always quantitatively based

Uses of Nutrient Criteria

— Basis for State/Tribal Water Quality Standards

— Resource assessment

— Setting of management priorities

— Evaluation of management projects

— Long-range planning

— Coordination of nutrient management planning and implementation with other

related programs

Rationale for Trophic Classification and Tiered Sampling Design

— Discussion of deriving nutrient reference conditions

— Discussion of cost-effectiveness of tiers, potential to evolve toward more

detailed sampling as needed

— Detailed discussion of importance of adequate data for decision making

compared to budget and level of certainty needed

II. Conducting Nutrient Surveys

Classification of the surface waters

Indicators

— How analyzed

— When to sample

— Where to sample

Survey Design

Data Storage and Processing

Interpretation

III. Trophic Classification
41

How to establish regions

Size classifications

Watershed classifications

Cultural development classes

IV. Indicators

For each indicator:

— Method of collection

— Storage and time constraints

— Method(s) of analysis

— Expected range of results and trophic state indicated by geographic region and

season

V. Sampling Design

Number of stations based on waterbody size

Placement of survey stations relative to characteristics of the waterbody and suspected

loading sites

Time of year and frequency of sampling

VI. Data Processing and Storage

Discuss models and software packages 

Regional databases and multi-State coordination of efforts

VII. Interpretation

Synopsis of indicator meanings

Discussion of interrelationships of trophic state and overenrichment indicators

Comprehensive interpretations

VIII. Detailed Nutrient Investigations for Cause and Effect Determination

Follow-up on initial surveys to generate definitive information
42

Seasonal adjustments

Relocation of some stations and addition of others

— Importance of basic survey continuity

IX. Management Response 

Should be broad-based and general to indicate potential as opposed to a directive to

the community

Types of loadings the indicators reflect

— BMPs and other protection or mitigation measures available

Approaches to achieve protection or change

— Local government

— Communities

— Property owners

— Businesses

Management Planning

— Incorporate the 10-step approach described in Chapter IV of this nutrient

strategy document

X. Evaluation Monitoring

A variation on the original survey plan is used to keep track of the response of the

waterbody to the protection or remediation effort

This information is used to assess the relative success of the project and to plan future

courses of action

— Evaluation of “before, during, and after” project data

Close the loop in the management process by returning to step 1 of the 10-step

process to plan the next phase of management or to apply these results to other

similar, nearby waterbodies.

Appendices 

Discussion of how States get from data gathering to using the information in

management decision making to incorporation into State policies.

Illustration of these experiences with case studies and names of contacts for further

information.
43

Appendix D: Drafting Committee for the National Nutrient Strategy

Office of Science and Technology Office of Wetlands, Oceans, and Watersheds

Nick Baer John Heisler

USEPA Office of Water USEPA Office of Water

Health and Ecological Criteria Division Oceans and Coastal Protection Division

(202) 260-1306 (202) 260-8632

Robert Cantilli, National Nutrient Program Kristen Martin

Coordinator USEPA Office of Water

USEPA Office of Water Assessment and Watershed Protection Division

Health and Ecological Criteria Division (202) 260-7108

(202) 260-5546

George Gibson

USEPA Office of Water

Health and Ecological Criteria Division

(202) 260-7580/(410) 573-2618

Patrick Ogbebor

USEPA Office of Water

Permits Division

(202) 260-6322
44

APPENDIX E: Excerpt from the Clean Water Action Plan

Reduce Nutrient Over-enrichment

Nutrients, in the appropriate amounts, are essential to the health and continued functioning of

aquatic ecosystems. Excessive nutrient loadings will, however, result in excessive growth of

macrophytes or phytoplankton and potentially harmful algal blooms (HAB), leading to oxygen

declines, imbalance of aquatic species, public health risks, and a general decline of the aquatic

resource. Nutrient over-enrichment has also been strongly linked to the large hypoxic zone in

the Gulf of Mexico and to recent outbreaks of Pfiesteria along the mid-Atlantic Coast.

State water quality reports indicate that over-enrichment of waters by nutrients (nitrogen and

phosphorus) is the biggest overall source of impairment of the nation’s rivers and streams,

lakes and reservoirs, and estuaries. In the 1996 National Water Quality Inventory, states

reported that 40 percent of surveyed rivers, 51 percent of surveyed lakes, and 57 percent of

surveyed estuaries were impaired by nutrient enrichment. Agriculture is the most widespread

source of these impairments, followed by municipal sewage treatment plants, urban runoff and

storm sewers, and various other nonpoint pollution sources, including air deposition. 

Define Nutrient Reduction Goals 

Although nutrient over-enrichment is clearly a major challenge for the nation’s waters, the

assessment of the seriousness and extent of the problem is often based on subjective criteria

that can result in widely varying assessments. Research to improve the basis for understanding

and assessing nutrient over-enrichment problems is critical to better control of nutrient levels

in waters and to meeting the nation’s clean water goals.

EPA is developing a strategy to establish an objective, scientifically sound basis for assessing

nutrient over- enrichment problems. Specifically, EPA will develop nutrient criteria -

numerical ranges for acceptable levels of nutrients (i.e., nitrogen and phosphorus) in water.

Unlike other criteria that EPA has developed, nutrient criteria will be established as a menu of

different numeric values based on the type of water body (i.e., river, estuary, lake) and the

region of the country in which the water is located. It is vital that this work be done to provide

the technical basis for pollution reduction plans. 

EPA will develop nutrient criteria for the various water body types and ecoregions of the

country by the year 2000. Under the Clean Water Act, states use pollutant criteria established

by EPA as the basis for adopting water quality standards. Within three years of EPA issuance

of applicable criteria, all states and tribes with water quality standards should have adopted

water quality standards for nutrients. Where a state or tribe fails to adopt a water quality

standard for nutrients within the three-year period, EPA will begin to promulgate the nutrient

criteria appropriate to the region and water body type. When promulgated, the EPA standard

would apply until a state or tribe adopts, and EPA approves, a revised standard. 
45

KEY ACTION: EPA will establish, by the year 2000, numeric criteria for nutrients (i.e.,

nitrogen and phosphorus) that are tailored to reflect the different types of water bodies (e.g.,

lakes, rivers, and estuaries) and the different ecoregions of the country, and will assist states in

adopting numeric water quality standards based on these criteria over the following three

years. If a state does not adopt appropriate nutrient standards, EPA will begin the process of

promulgating nutrient standards. 
46

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