APPENDIX E 

An Approach for Evaluating 

Numeric Water Quality Criteria 

for Wetlands Protection 

WATER QUALITY STANDARDS HANDBOOK 

SECOND EDITION 
AN APPROACH FOR EVALUATING NUMERIC WATER QUALITY CRITERIA 

FOR WETLANDS PROTECTION 

by 

Cynthia A. Hagley and Debra L. Taylor 

Asci Corporation 

Duluth, Minnesota 55804 

Project Officer 

William D. Sanville 

Project Leader 

Environmental Research Laboratory 

Duluth, Minnesota 55804 

DU: BIOL 

ISSUE: A 

PPA: 16 

PROJECT: 39 

DELIVERABLE: 8234 

July 8, 1991 
ABSTRACT 

Extension of the national numeric aquatic life criteria to 

wetlands has been recommended as part of a program to develop 

standards and criteria for wetlands. This report provides an 

overview of the need for standards and criteria for wetlands and 

a description of the numeric aquatic life criteria. The numeric 

aquatic life criteria are designed to be protective of aquatic 

life and their uses for surface waters, and are probably 

applicable to most wetland types. This report provides a 

possible approach, based on the site-specific guidelines, for 

detecting wetland types that might not be protected by direct 

application of national numeric criteria. The evaluation can be 

simple and inexpensive for those wetland types for which 

sufficient water chemistry and species assemblage data are 

available, but will be less useful for wetland types for which 

these data are not readily available. The site-specific approach 

is described and recommended for wetlands for which modifications 

to the numeric criteria are considered necessary. The results of 

this type of evaluation, combined with information on local or 

regional environmental threats, can be used to prioritize wetland 

types (and individual criteria) for further site-specific 

evaluations and/or additional data collection. Close 

coordination among regulatory agencies, wetland scientists, and 

criteria experts will be required. 

i 
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

OFFICE OF 

WATER 

SUBJECT: Numeric Water Quality Criteria for Wetlands 

FROM: William R. Diamond, Director 

Standards and Applied Science Division 

Office of Science and Technology 

TO: Water Management Division Directors (Regions I-X) 

Environmental Services Division Directors (Regions I-X) 

State Water Pollution Control Agency Directors 

The purpose of this memorandum is to provide you with a copy 

of a report entitled "An Approach for Evaluation of Numeric Water 

Quality Criteria for Wetlands Protection", prepared by EPA’s 

Environmental Research Laboratory in Duluth, Minnesota. This 

report was requested in the early stages of planning for wetland 

water quality standards to assess the applicability of EPA's 

existing numeric aquatic life criteria methodology for wetlands. 

This report was prepared by the Wetlands Research Program and is 

part of the Agency's activities to assist States with developing 

water quality standards for wetlands. 

The report evaluates EPA's numeric aquatic life criteria to 

determine how they can be applied to wetlands. Numeric aquatic 

life criteria are designed to be protective of aquatic life for a 

wide range of surface water types. The report suggests that most 

numeric aquatic life criteria are applicable to most wetland 

types. 

However, there are some wetland types where EPA's criteria 

are not appropriate. This report presents an approach that 

States may use as a screening tool to detect those wetland types 

that may be under- or overprotected by EPA's criteria. The 

proposed approach relies on data readily available from EPA's 

304(a) criteria documents, as well as species assemblages and 

water quality data from individual wetland types. The results of 

this type of simple evaluation can be used to prioritize wetland 

types where further evaluation may be needed prior to setting 

criteria. Two example analyses of the approach are included in 

the report. EPA's site-specific criteria development guidelines 

can then be used to modify criteria if appropriate. 
This report compiles existing information from EPA's 304(a) 

criteria guidance documents and site-specific criteria 

methodologies and does not contain new guidance or policy. The 

report has been peer reviewed by ERL/Duluth scientists who 

develop EPA's 304 criteria. The report also has been reviewed by 

the Standards and Applied Science Division and the Wetlands 

Division. 

If you have additional questions on the information 

contained in this report or its applications, contact the 

following persons: David Sabock, Water Quality Standards Branch, 

at 202-475-7315 regarding designated uses and water quality 

standards policies; Bob April, Ecological Risk Assessment Branch, 

at 202-475-7315, regarding EPA's aquatic life criteria: or Bill 

Sanville, Environmental Research Laboratory/Duluth, at 218-720- 

5500, regarding the research for this report. 

Attachment 

cc: Water Quality Branch Chiefs (Regions I-X) 

Water Quality Standards Coordinators (Regions I-X) 

Wetlands Coordinators (Regions I-X) 

David Sabock 

Bob April 

Bill Sanville 

2 
CONTENTS 

Abstract i 

Tables iii 

Acknowledgements iv 

1. 

2. 

3. 

4. 

5. 

6. 

Introduction 

Need for standards for wetlands 

Proposed approach to development of wetland 

standards 

Purpose of this document 

Current Surface Water Standards and Criteria 

Description of standards and criteria 

Development of national aquatic life numeric 

criteria 

Site-specific guidelines 

The Need for Evaluating Numeric Water 

Quality Criteria: Use of the Site-Specific 

Guidelines 

Overall relevance of criteria to wetlands 

Wetland variability 

Use of the site-specific guidelines for 

wetlands 

Aquatic plants 

Evaluation Program 

Classification 

Evaluating the appropriateness of direct 

application of criteria 

Developing site-specific criteria 

Example Analyses 

Example 1 

Example 2 

Summary of the example analyses 

Conclusions 

References 

Appendices 

A. Sources used in species habitat identification 

for Minnesota marshes 

B. Sources used in species habitat identification 

for prairie potholes 

1 

1 

3 

4 

6 

6 

7 

8 

9 

9 

10 

10 

14 

16 

16 

17 

18 

19 

19 

21 

24 

26 

28 

31 

32 

ii 
TABLES 

Number Page 

1 

2 

3 

4 

5 

6 

7 

8 

9 

Freshwater numeric aquatic life criteria 

Suitability of wetland species to fill minimum 

family requirements for six criterion chemicals 

Some conditions recommended for dilution water 

for water quality criteria testing 

Effects of cofactors on criterion chemical toxicity 

Water chemistry for selected Minnesota marshes 

Comparison of test species with Minnesota marsh 

biota for six criterion chemicals 

Number of species tested for acute criteria and 

percentage of test species that are not found in 

Minnesota marshes or oligosaline prairie potholes 

Water quality characteristics for oligosaline 

prairie potholes 

Comparison of test species with prairie pothole 

biota for six criterion chemicals 

33 

34 

35 

36 

37 

38 

40 

41 

42 

iii 
ACKNOWLEDGEMENTS 

Preparation of this document has been funded by the U.S. 

Environmental Protection Agency. This document has been prepared 

at the EPA Environmental Research Laboratory in Duluth, 

Minnesota, through Contract # 68033544 to AScI Corporation. This 

document has been subjected to the Agency's peer and 

administrative review. Excellent reviews and assistance were 

received from C. Stephan, R. Spehar, C. Johnston, E. Hunt, D. 

Robb, and J. Minter. 

iv 
SECTION 1 

INTRODUCTION 

NEED FOR STANDARDS FOR WETLANDS 

Wetlands have been studied and appreciated for a relatively 

short time in relation to other types of aquatic systems. The 

extent of their value in the landscape has only recently been 

recognized: in fact, a few decades ago government policies 

encouraged wetland drainage and conversion. Wetlands 

traditionally have been recognized as important fish and wildlife 

habitats, and it is estimated that over one-third of U.S. 

endangered species require wetland habitat for their continued 

existence. Some of their many other values, however, have become 

apparent only recently. These include attenuation of flood 

flows, groundwater recharge, shoreline and stream bank 

stabilization, filtering of pollutants from point and nonpoint 

sources, unique habitats for both flora and fauna, and 

recreational and educational opportunities.1 

Impacts to Wetlands 

Despite new appreciation of the valuable functions that 

wetlands perform in the landscape, they continue to be destroyed 

and altered at a rapid pace. Since pre-settlement times over 

half of the wetlands in the continental U.S. have been destroyed, 

and losses over the last few decades have remained high.2 These 

figures only represent actual loss of acreage and do not account 

for alterations to or contamination of still-extant wetlands. 

The causes of wetland destruction and degradation include:3 

* Urbanization - Resulting in drainage and filling, 

contamination, and ecological isolation of wetlands. 

* Agriculture Conversion - Drainage, cropping, and 

grazing which change or destroy wetland structure and 

ecological function. 

* Water Resource Development - Water flow alterations to 

wetlands from diking, irrigation diversions, 

alterations to rivers for navigation, diversions for 

1 
water supply, and groundwater pumping. These result in 

changes in the hydrology that sustains the wetland 

system. 

* Chemical Pollution - From point and nonpoint sources, 

hazardous waste sites, mining, and other activities. 

These can overwhelm the assimilative capacity of 

wetlands or be toxic to wetland organisms. 

* Biological Disturbances - Introduction or elimination 

of plant and animal species that affect ecosystem 

processes. 

Gaps in Federal Regulatory Programs 

Existing Federal regulatory programs intended to reduce some 

of the impacts described above leave major gaps in the protection 

of wetlands. Section 404 of the Clean Water Act (CWA) requires a 

permit to be obtained from the Army Corps of Engineers, in 

cooperation with the U.S. Environmental Protection Agency (EPA), 

before dredged material or fill can be discharged into waters of 

the United States. Alterations such as drainage, water 

diversion, and chemical contamination are not covered by Section 

404 unless material will be discharged into the wetland in 

association with such alterations. The Resource Conservation and 

Recovery Act, which regulates the disposal of hazardous wastes, 

and the CWA, which regulates contamination from waste-water 

discharges and nonpoint-source pollution, could provide 

protection from certain impacts, but they have not been used 

consistently to regulate impacts to wetlands. Programs designed 

to protect endangered species, migratory birds, and marine 

mammals have also been used to reduce impacts to wetlands, 

"the application of these programs also has been uneven."4 

but 

Gaps in State Regulatory Programs 

Wetland regulations vary greatly among States. Some States 

are now developing narrative standards for wetlands (e.g. 

Wisconsin, Rhode Island, and others). On the other hand, 

although wetlands are included in the Federal definition of 

"waters of the United States" and are protected by Section 101(a) 

of the CWA, not all States include them as "waters of the State" 

in their definitions. A review conducted in 1989 by the EPA 

Office of Wetlands Protection and the Office of Water Regulations 

and Standards found that only 27 of 50 States mentioned wetlands 

in definitions of State waters. The review verified that there 

generally is a lack of consideration given to water quality 

standards for wetlands.' 

2 
Effective Use of Existing Regulatory Options 

Although some impacts (e.g. excavation, most drainage, and 

destruction of vegetation) are not addressed by the current 

implementation of existing regulations and programs, much of the 

chemical contamination of wetlands could be controlled through 

existing Federal and State water pollution control laws.‘ The 

National Wetlands Policy Forum recommended that EPA and State 

water pollution control agencies review the implementation of 

their water quality programs to ensure that the chemical 

integrity of wetlands is adequately protected. The Forum 

stressed the need to develop water quality standards designed to 

protect sensitive wetlands.4 

Under Section 401 of the CWA, States have authority to 

authorize, condition, or deny all Federal permits or licenses in 

order to comply with State water quality standards, including, 

but not limited to, Sections 402 and 404 of the CWA, Sections 9 

and 10 of the Rivers and Harbors Act, and Federal Energy 

Regulatory Commission licenses. States with water quality 

standards that apply to or are specifically designed for wetlands 

can use 401 certification much more effectively as a regulatory 

tool. 

As wetlands receive more recognition as important components 

of State water resources, the need for testing the applicability 

of some existing guidelines and standards to wetlands regulation 

becomes more apparent. 

PROPOSED APPROACH TO DEVELOPMENT OF WETLAND STANDARDS 

The EPA Office of Water Regulations and Standards and Office 

of Wetlands Protection recently completed a document entitled, 

"National Guidance: Water Quality Standards for Wetlands."6 It 

recommends a two-phased approach for the development of water 

quality standards for wetlands. In the first 3-year phase of 

this program, standards for wetlands would be developed using 

existing information in order to provide protection to wetlands 

consistent with the protection afforded other State waters. 

Technical support for this initial phase will be provided through 

documents such as this one, which focuses on the application of 

existing numeric criteria to wetlands. These criteria are widely 

used. Applying them to wetlands requires a small amount of 

effort and can be accomplished quickly. 

The development of narrative biocriteria is also required in 

the initial phase of standards development. The long-term goal 

(3-10 years) of this program is to develop numeric biocriteria 

for wetlands. It is anticipated that both narrative and numeric 

3 
biocriteria can provide a more integrative estimate of wholewetland health and better identification of impacts and trends 

than can be attained by traditional numeric chemical criteria. 

Field-based, community-level biosurveys can be implemented to 

complement, and help validate, laboratory-based conclusions. 

Results of such surveys can be used to monitor wetlands for 

degradation and establish narrative or numeric biocriteria or 

guidance which take into account "real world" biological 

interactions and the interactions of multiple stressors. 

More information on the development of numeric biocriteria 

will be available in a guidance document in coming years. 

Technical guidance to support the development of biological 

criteria for wetlands has also been prepared.' This guidance 

provides a synthesis of technical information on field studies of 

inland wetland biological communities. 

PURPOSE OF THIS DOCUMENT 

A number of steps are needed to develop wetland standards. 

The document, "National Guidance: Water Quality Standards for 

Wetlands," mentioned above, provides general guidelines to the 

States for each of the following steps: the inclusion of 

wetlands in definitions of State waters, the relationship between 

wetland standards and other water-related programs, use 

classification systems for wetlands, the definition of wetland 

functions and values, the applicability of existing narrative and 

numeric water quality criteria to wetlands, and the application 

of antidegradation policies to wetlands. 

The technical document for biological criteria7 and this 

report are companions to the guidance document described above. 

This report is directed primarily toward wetland scientists 

unfamiliar with water quality regulation and is intended to 

provide a basis for dialogue between wetland scientists and 

criteria experts regarding adapting numeric aquatic life criteria 

to wetlands. More specifically: 

1) It provides background information and an overview of 

water quality standards and numeric chemical criteria, including 

application to wetlands. 

2) The need for evaluating numeric water quality criteria is 

discussed. The site-specific guidelines are introduced and 

discussed in two contexts: a) as an initial screening tool to 

ensure that water quality in extreme wetland types is adequately 

protected by criteria, and b) in terms of using the site-specific 

guidelines to modify criteria for wetlands where criteria might 

be over or underprotective. 

4 
3) An approach is described that uses information available 

from criteria documents and is designed to: a) detect wetland 

types where water quality is not clearly protected by existing 

criteria, and b) help prioritize further evaluations and research 

efforts. 

4) A simple test of the approach is presented with two 

examples. Results are not considered conclusive and are 

presented only as an example of the procedure. 

Most of the data and examples are based on the freshwater 

acute criteria. A similar approach should be equally applicable 

to the saltwater acute criteria and to both saltwater and 

freshwater chronic criteria. 

5 
SECTION 2 

CURRENT SURFACE WATER STANDARDS AND CRITERIA 

This section describes how criteria are used in State 

standards, how national numeric criteria are derived, and what 

options are currently available for modifying national aquatic 

life criteria. 

DESCRIPTION OF STANDARDS MD CRITERIA 

Surface waters are protected by Section 101(a) of the CWA 

with the goal: "to restore and maintain the chemical, physical, 

and biological integrity of the nation's waters." State water 

quality standards are developed to meet this goal. 

State Standards 

There are two main components to establishing a standard: 

1) The level of water quality attainable for a particular 

waterbody, or the designated use of that waterbody (e.g. 

recreational, fishery, etc.) is determined; 2) Water quality 

criteria (usually a combination of narrative and numeric) are 

established to protect that designated use. Water quality 

standards also contain an antidegradation policy "to maintain and 

protect existing uses and water quality, to provide protection 

for higher quality waters, and to provide protection for 

outstanding national resource waters."8 State standards for a 

particular waterbody must be met when discharging wastewaters. 

The "National Guidance: Water Quality Standards for Wetlands"6 

outlines a basic program to achieve these goals for wetlands. 

Aquatic Criteria 

Narrative Criteria-- 

Narrative criteria are statements, usually expressed in a 

"free from . . . " format. For example, all States have a narrative 

statement in their water quality standards which requires that 

their waters not contain "toxic substances in toxic amounts." 

Narrative criteria are typically applied at the State level when 

combinations of pollutants must be controlled or when pollutants 

are present which are not listed in State water quality 

6 
standards.8 States must document the process by which they 

propose to implement these narrative criteria in their standards. 

Numeric Criteria-- 

Pollutant-specific numeric criteria are used by the States 

when it is necessary to control individual pollutants in order to 

protect the designated use of a waterbody. Fate and transport 

models commonly are used to translate these criteria into permit 

limits for individual dischargers. Some criteria apply Statewide and others are specific to particular designated uses or 

waterbodies. 

National numeric criteria are developed by EPA based on best 

available scientific information. They serve as recommendations 

to assist States in developing their own criteria and to assist 

in interpreting narrative criteria.9 These include human health 

and aquatic life pollutant-specific criteria and whole effluent 

toxicity criteria. Sediment criteria are now being developed. 

States can adopt national numeric criteria directly. 

Alternatively, site-specific criteria may be developed using EPAspecified guidelines, and State-specific criteria can be derived 

using procedures developed by the State.8 

DEVELOPMENT OF NATIONAL AQUATIC LIFE NUMERIC CRITERIA 

National aquatic life criteria are usually derived using 

single-species laboratory toxicity tests. Tests are repeated 

with a wide variety of aquatic organisms for each chemical. The 

criteria are designed to protect against unacceptable effects to 

aquatic organisms or their uses caused by exposures to high 

concentrations for short periods of time (acute effects), to 

lower concentrations for longer periods of time (chronic 

effects), and to combinations of both.9 EPA criteria are 

composed of 1) magnitude (what concentration of a pollutant is 

allowable): 2) duration of exposure (the period of time over 

which the in-stream concentration is averaged for comparison with 

criteria concentrations): and 3) frequency (how often the 

criterion can be exceeded without unacceptably affecting the 

community).10 Separate criteria are determined for fresh water 

and salt water. Field data are used when appropriate. 

All acceptable data regarding toxicity to fish and 

invertebrates are evaluated for inclusion in the criteria. Data 

on toxicity to aquatic plants are evaluated to determine whether 

concentrations of the chemical that do not cause unacceptable 

effects to aquatic animals will cause unacceptable effects to 

plants. Bioaccumulation data are examined to determine if 

residues in the organisms might exceed FDA action levels or cause 

known effects on the wildlife that consume them. For a Complete 

7 
description of the procedures for deriving ambient criteria, 

consult the "National Guidelines" (1985).9 

Numeric water quality criteria are designed to protect most 

of the species inhabiting a site.9 A wide variety of taxa with a 

range of sensitivities are required for deriving criteria. 

Guidelines are followed to determine the availability of 

sufficient experimental data from enough appropriate taxa to 

derive a criterion. For example, to derive a freshwater Final 

Acute Value for a chemical, results of acute tests with at least 

one species of freshwater animal in at least eight different 

families are required. Acute and chronic values can be made to 

be a function of a water quality characteristic such as Ph, 

salinity, or hardness, when it is determined that these 

characteristics impact toxicity, and enough data exist to 

establish the relationship. Table 1 lists the chemicals for 

which freshwater aquatic life criteria have been developed and 

indicates which of those criteria are pH, hardness, or 

temperature dependent. 

SITE-SPECIFIC GUIDELINES 

An option for modifying national aquatic life water quality 

criteria to reflect local conditions is presented in the sitespecific guidelines. States may develop site-specific criteria 

by modifying the national criteria for sites where 1) water 

quality characteristics, such as pH, hardness, temperature, etc., 

that might impact toxicity of the pollutants of concern differ 

from the laboratory water used in developing the criterion; or 2) 

the types of organisms at the site differ from, and may be more 

or less sensitive than, those used to calculate the criterion; or 

3) both may be true. Site-specific criteria take local 

conditions into account to provide an appropriate level of 

protection. They can also be used to set seasonal criteria when 

there is high temporal variability.8 

A testing program can be used to determine whether sitespecific modifications to criteria are necessary. This program 

may include water quality sampling and analysis, a biological 

survey, and acute and chronic toxicity tests.11 If site-specific 

modifications are deemed necessary, 3 separate procedures are 

available for using site-specific guidelines to modify criteria 

values, including the recalculation procedure, the indicator 

species procedure, and the resident species procedure. These 

will be discussed more fully in the next section. 

8 
SECTION 3 

THE NEED FOR EVALUATING NUMERIC WATER QUALITY CRITERIA: 

USE OF THE SITE-SPECIFIC GUIDELINES 

OVERALL RELEVANCE OF CRITERIA TO WETLANDS 

The national aquatic life criteria have been developed to 

provide guidance to the States for the protection of aquatic life 

and their uses in a variety of surface waters. They are designed 

to be conservative and "'... have been developed on the theory 

that effects which occur on a species in appropriate laboratory 

tests will generally occur on the same species in comparable 

field situations. All North American bodies of water and 

resident aquatic species and their uses are meant to be taken 

into account, except for a few that may be too atypical ..."9 A 

wide variety of taxonomic groups sensitive to many materials are 

used in testing, including many taxa common to both wetlands and 

other surface waters. In order to ensure that criteria are 

appropriately protective, water used for testing is low in 

particulate matter and organic matter, because these substances 

can reduce availability and toxicity of some chemicals. For 

these reasons, the "National Guidance: Water Quality Standards 

for Wetlands" states that, in most cases, criteria should be 

protective of wetland biota.6 

Although the water quality criteria are probably generally 

protective of wetlands and provide the best currently available 

tool for regulating contamination from specific pollutants, there 

are many different types of wetlands with widely variable 

conditions. There might be some wetland types where the resident 

biota or chemical and physical conditions are substantially 

different from what the criteria were designed to protect. These 

differences could result in underprotection or overprotection of 

the wetland resource. This section discusses the use of sitespecific guidelines for wetland types for which certain criteria 

might be over or underprotective, but its primary focus is to 

provide a mechanism to identify wetland types that might be 

underprotected by certain criteria and that might require further 

research. 

9 
WETLAND VARIABILITY 

Wetlands are usually located at the interface between 

terrestrial systems and truly aquatic systems, and so combine 

attributes of both." They are intermediate between terrestrial 

and aquatic systems in the amount of water they store and process 

and are very sensitive to changes in hydrology.'* Their chemical 

and physical properties, such as nutrient availability, degree of 

substrate anoxia, soil salinity, sediment properties, and pH are 

influenced greatly by hydrologic conditions. Attendees at a 

Wetlands Water Quality Workshop (held in Easton, Maryland in 

August, 1988) listed the most common ways in which wetlands 

differ from "typical" surface waters: higher concentrations of 

organic carbon and particulate matter, more variable and 

generally lower pH, more variable and generally lower dissolved 

oxygen, more variable temperatures, and more transient 

availability of water." 

There is also high variability among wetland types. 

Wetlands, by definition, share hydrophytic vegetation, hydric 

soils, and a water table at or near the surface at some time 

during the growing season. Beyond these shared features, 

however, there is tremendous hydrological, physical, chemical, 

and biological variability. For example, an early 

classification system for wetlands "Circular 39", listed 20 

distinctly different wetland types 14 and the present "Cowardin" 

system lists 56 classes of wetlands.15 This variability makes it 

important to evaluate different wetland types individually. 

USE OF THE SITE-SPECIFIC GUIDELINES FOR WETLANDS 

The site-specific guidelines outlined in Section 2 are 

designed to address the chemical and biological variability 

described above. Determining the need for site-specific 

modifications to criteria requires a comparison of the aquatic 

biota and chemical conditions at the site to those used for 

establishing the criterion. This comparison is useful for 

identifying wetland types that might require additional 

evaluation. The three site-specific options are discussed in the 

context of their general relevance to wetlands and are used in 

this discussion to provide a framework for evaluating the 

protectiveness of criteria for wetlands. 

In most cases, because of the conservative approach used in 

the derivation of the criteria, use of the site-specific 

guidelines to modify criteria results in no change or in their 

relaxation, provided that an adequate number of species are used 

in the calculations. However, criteria can also become more 

10 
restrictive. Newly tested species could be especially sensitive 

to certain pollutants, or extreme water conditions found in some 

surface waters or wetland types might not reduce the toxicity of 

a chemical. Disease, parasites, predators, other pollutants, 

contaminated or insufficient food, and fluctuating and extreme 

conditions might all affect the ability of organisms to withstand 

toxic pollutants.9 

Appropriateness of Testing Organisms: Recalculation Procedure . 

The first option given in the site-specific guidelines is 

the recalculation procedure.8,11 This approach is designed to 

take into account differences between the sensitivity of resident 

species and those used to calculate a criterion for the material 

of concern. It involves eliminating data from the criterion 

database for species that are not resident at that site. It 

could require additional resident species testing in laboratory 

water if the number of species remaining for recalculating the 

criterion drops below the minimum data requirements. "Resident" 

species include those that seasonally or intermittently exist at 

a site.11,16 

Use of the recalculation procedure will not necessarily 

result in a higher acute criterion value (less restrictive), even 

if sensitive species are eliminated from the dataset and minimum 

family requirements are met. The number of families used to 

calculate Final Acute Values is important. If a number of nonwetland species are dropped out of the calculation without adding 

a sufficient number of new species, a lower (more restrictive) 

Final Acute Value can result, because data are available for 

fewer species." 

Similarity of Required Taxa and Typical Wetland Species-- 

The variety of test species required to establish the 

national numeric criteria was chosen to represent a wide range of 

taxa having a wide range of habitat requirements and sensitivity 

to toxicants. Establishment of a freshwater Final Acute Value 

for a chemical requires a minimum of 8 different types of 

families to be tested. These include: 1) the family Salmonidae; 

2) a second family of fish, preferably a warmwater species: 3) a 

third family in the phylum Chordata (fish, amphibian, etc.): 4) a 

planktonic crustacean: 5) a benthic crustacean: 6) an insect: 7) 

a family in a phylum other than Arthropoda or Chordata; and 8) a 

family in any order of insect or phylum not already represented.9 

When a required type of family does not exist at a site, the 

guidelines for the recalculation procedure specify that 

substitutes from a sensitive family, resident in the site, should 

be added to meet the minimum family data requirement. should it 

happen that all resident families have been tested and the 

11 
minimum data requirements still have not been met, the acute 

toxicity value from the most sensitive resident family that has 

been tested should be used as the site-specific value. 

Most of the required families are probably well-represented 

in most wetland types. Some types of wetlands, however, seldom 

or never contain fish, and most wetland types do not support 

salmonids or aquatic insects requiring flowing water. 

General Evaluation of Species Suitability-- 

Table 2 presents six criterion chemicals chosen as examples 

and the eight taxonomic groups required to establish criteria. 

The chemicals include two organochlorines: polychlorinated 

biphenyls (PCBs - used in industrial applications, 

environmentally-persistent, bioaccumulate) and pentachlorophenol 

(widely used fungicide and bactericide); one organophosphate: 

parathion (insecticide); two metals: zinc and chromium (VI); and 

cyanide. 

The species used for acute toxicity testing for each of the 

six chemicals have been broken down by taxonomic group and 

evaluated based on the likelihood that those species can be found 

in wetlands. Except for the unsuitability of the Salmonidae to 

most wetland types, most of the taxonomic groups are wellrepresented for the six chemicals used as examples. Wetland 

species were not present in the list of species used to calculate 

the Final Acute Value for the "non-arthropod/non-chordate" and 

"another insect or new phylum" groups for a few of the criteria. 

This is not because these groups are not represented in wetlands. 

These are very general classifications. For example, the "nonarthropod/non-chordate" group can include rotifers, annelids, and 

mollusks among other phyla, all of which should have many 

representatives in most types of wetlands. There is a large 

degree of variation in the total number of species tested for the 

six chemicals used as examples, ranging from 10 fish and 

invertebrates for polychlorinated biphenyls (PCBs) to 45 for zinc 

(Table 7). Criteria based on smaller numbers of species are less 

likely to include a sufficient number of wetland species to 

fulfill the minimum family requirements. Additional toxicity 

testing, using laboratory water and wetland species from the 

missing families, can be done to fill these gaps. 

While the general taxonomic groups required for toxicity 

testing are fairly well represented in wetlands, the similarity 

between the genera and species inhabiting individual wetland 

types and those used for criteria testing varies widely among 

criteria and wetland types. Species chosen for toxicity testing 

were seldom or never chosen with wetlands in mind. In addition, 

relatively little is known about species assemblages in some 

types of wetlands (particularly in those lacking surface waters, 

12 
such as wet meadows or bogs). Defining typical wetland taxa is 

difficult. For example, while most m of wetlands do not 

support salmonids, Coho salmon are highly dependent on wetlands 

in Alaska, where there is a higher percentage and acreage of 

wetlands than in any other State. Part of the utility of the 

evaluation proposed here is in identifying where significant gaps 

in data exist. 

. 

. uence of Cofactors. -or Species Proca 

The second of the three site-specific procedures, the 

indicator species procedure, accounts for differences in 

biological availability and/or toxicity of a material caused by 

physical and/or chemical characteristics of the site water, or 

cofactors. For the acute test, the effect of site water is 

compared to the effect of laboratory water, using at least two 

resident species or acceptable non-resident species (one fish and 

one invertebrate) as indicators. A ratio is determined, which is 

used to modify the Final Acute Value. See Carlson et al. (1984) 

for information and guidelines for determination of site-specific 

chronic values." 

Suitability of Standard Testing Conditions-- 

Standard aquatic toxicity tests are performed using natural 

or reconstituted dilution water that should not of itself affect 

the results of toxicity tests. For example, organic carbon and 

particulate matter are required to be low to avoid sorption or 

complexation of toxicants, which might lower the toxicity or 

availability of some criterion chemicals. Recommended acute test 

conditions for certain water quality characteristics of fresh and 

salt water are listed in Table 3. Wetlands, as well as some 

types of surface waters, can have values far outside the ranges 

used for standard testing for some of these characteristics (most 

notably total organic carbon, particulate matter, pH, and 

dissolved oxygen). Wetland types can be evaluated to identify 

these extremes. 

Wetland Cofactors-- 

Many water quality characteristics can 1) act as cofactors 

to affect the toxicity of pollutants (e.g. alkalinity/acidity, 

hardness, ionic strength, organic matter, temperature, dissolved 

oxygen, suspended solids); 2) can be directly toxic to organisms 

(e.g. un-ionized ammonia, high or low pH, hydrogen sulfide, low 

dissolved oxygen); or 3) can interfere mechanically with feeding 

and reproduction (e.g. suspended solids). The criteria for some 

of these water quality characteristics can be naturally exceeded 

in many wetland types, as well as in some lakes and streams. 

Hardness, pH, and temperature adjustments built into a few 

of the criteria account for effects from these cofactors in a few 

13 
ca8es, but no other cofactors are now included in the criteria, 

despite some known effects. For example, alkalinity, salinity, 

and suapended solids, in addition to pH and hardness, are known 

to affect the toxicities of heavy metals and ammonia. These 

cofactors are not included in the criteria primarily because 

there are insufficient data.' For example, most toxicity tests 

have been performed under conditions of low or high salinity, so 

that estuaries, where salinity values can vary greatly, may 

require 

metals." 

salinity-dependent site-specific criteria for some 

An initial evaluation of the adequacy of protection 

provided to a wetland type by a criterion should take possible 

cofactor effects into account. 

. 

. e&nt mcies Procew 

The resident species procedure accounts for differences in 

both species sensitivity and water quality characteristics." 

This procedure is costly, because it requires that a complete 

minimum dataset be developed using site water and resident 

species. It is designed to compensate concurrently for 

differences in the sensitivity range of species represented in 

the dataset used to derive the criterion and for site water 

differences which may markedly affect the biological availability 

and/or toxicity of the chemical." 

AQUATIC PLANTS 

One of the most notable differences between wetlands and 

other types of surface waters is the dominance (and importance) 

of aquatic macrophytes and other hydrophytic vegetation in 

wetlands. Aquatic plants probably constitute the majority of the 

biomass in most wetland types. 

Few data concerning toxicity to aquatic plants are currently 

required for deriving aquatic life criteria. Traditionally, 

procedures for aquatic toxicity tests on plants have not been as 

well developed as for animals. Although national numeric 

criteria development guidelines state that results of a test with 

a freshwater alga or vascular plant "should be available" for 

establishing a criterion, they do not require that information.' 

The Final Plant Value is the lowest (most sensitive) result from 

tests with important aquatic plant species (vascular plant or 

alga), in which the concentrations of test material were measured 

and the endpoint was biologically important. Plant values are 

compared to animal values to determine the relative sensitivities 

of aquatic plants and animals. If plants are "among the aquatic 

organisms that are most sensitive to the material," results of a 

second test with a plant from another phylum are included.9 

14 
Results of tests with plants usually indicate that criteria 

which protect aquatic animals and their uses also protect aquatic 

plants and their uses.' As criteria are evaluated for their 

suitability for wetlands, however, plant values should be 

examined carefully. Additional plant testing may be advisable in 

some cases. If site-specific adjustments are made to some 

criteria, they could result in less restrictive acute and chronic 

values for animals. Some plant values could then be as sensitive 

or more sensitive than the animal values. Chemicals with fairly 

sensitive plant values include: aluminum, arsenic(III), cadmium, 

chloride, chromium(VI), cyanide, and selenium(V1). For example, 

fish are generally much more sensitive to cyanide than 

invertebrates. If the recalculation procedure was used to 

develop a site-specific cyanide criterion for a wetland type 

containing no fish, values for these sensitive species would be 

replaced in the calculation, possibly by less sensitive species. 

A less restrictive criterion could result, possibly making the 

plant value more sensitive than the animal value. Therefore, 

additional consideration should be given to plant toxicity data 

for wetland systems. 

15 
SECTION 4 

EVALUATION PROGRAM 

The direct application of existing aquatic life criteria to 

wetlands is assumed to be reasonable in most cases. It provides 

a practical approach towards protecting the biological integrity 

of wetlands. The following evaluation program offers a possible 

strategy to identify extreme wetland types that might be 

underprotected by some criteria, to prioritize wetland types and 

criterion chemicals for further testing or research, and to 

identify gaps in available data. The approach can be helpful for 

identifying those instances where modifications to existing 

criteria might be advisable. The proposed evaluation program 

offers a screening tool to begin to answer the following 

questions: 1) Are there some wetland types for which certain 

criteria are underprotective? 2) For criteria in wetland types 

that cannot be applied directly, can site-specific guidelines be 

used to modify the criteria to protect the wetland? 3) Will 

additional toxicity testing under wetland conditions and with 

wetland species be necessary in some cases in order to establish 

site-specific criteria? 

The proposed approach relates species and water quality 

characteristics of individual wetland types to species and water 

quality characteristics important in deriving each criterion. It 

involves identifying wetland types of concern, identifying 

cofactors possibly affecting toxicity for the criteria of 

interest, gathering data on the biota and water quality 

characteristics of the wetland type, and comparing to data used 

to derive the criterion. 

CLASSIFICATION 

The proposed program for the evaluation of the suitability 

of aquatic life criteria discussed in this section can be done 

separately for individual wetland types. These can be defined in 

the classification process, which is the first step in developing 

standards for wetlands. The classification process requires the 

identification of the various structural types of wetlands and 

identification of their functions and values.6 The 

classification should provide groups of wetlands that are similar 

16 
enough structurally and functionally so that they can reasonably 

be expected to respond in kind to inputs of toxic chemicals. 

EVALUATING THE APPROPRIATENESS OF DIRECT APPLICATION OF CRITERIA 

Information Needed 

1. Identification of cofactors. Cofactors potentially 

affecting mobility and biological availability for each criterion 

chemical should be identified. Cofactors known to affect each 

criterion chemical are listed in individual national criteria 

documents and are summarized in Table 4. The absence of a 

relationship between a cofactor and a chemical on Table 4 does 

not ensure that no relationship exists, merely that none was 

discussed in the criteria document. The chemistry of the effects 

of the cofactors on the chemicals is often very complicated, and 

limited data are available regarding some of the relationships. 

The approach presented here is simplistic and is geared toward 

directing further efforts. Other sources of information, in 

addition to the criteria documents, should be consulted when 

actually applying this approach. Criteria that include hardnessor pH-dependent correction factors (Table 1) should apply 

directly to wetlands unless the wetland type has extremes of pH 

or hardness well outside the ranges used in toxicity testing. 

For example, the pH of acid bogs can be as low as 3.5, well below 

the 6.5 lower limit for toxicity testing (Table 3). 

2. Comparison to wetland water chemistry. Natural levels 

and variability of those cofactors should be identified as well 

as possible for each major wetland type of interest. Wetlandsrelated information can be accumulated through consultation with 

wetland researchers, through literature searches, and from 

monitoring agencies. 

3. Comparison of species lists. Species lists of fish, 

invertebrates, and plants should be compiled for each wetland 

type and compared to lists of species used for testing each 

criterion. Lists should be evaluated on two levels: a) Species 

level - Are the species used for toxicity testing representative 

(the same species or genera, or "similar" in terms of sensitivity 

to toxicants) of the species found in the wetland type? 

b) Family level - Does the wetland contain suitable 

representatives for each of the families listed in the minimum 

family requirements?8,11 Consultation with fish and invertebrate 

specialists, plant ecologists, and wetlands experts will be 

necessary to do this comparison. 

17 
Adoption of Existing Water Quality Criteria 

The existing water quality criterion should be suitable for 

that wetland type if the following are true: 

1. Important cofactor levels are not naturally exceeded in 

the wetland to a degree that might seriously affect toxicity or 

availability of the chemical. Would toxicity likely be higher, 

lower, or not influenced by typical levels or extremes of a 

particular cofactor in a particular wetland type? 

2. Sufficient species or genera used for aquatic toxicity 

testing are found in the wetland type so that the minimum family 

requirements can be met by resident wetland species. 

Consultation between wetland scientists and criteria experts will 

be necessary in many cases to make judgements on how wellrepresented some wetland types are. 

3. The criterion itself is not naturally exceeded in the 

wetland. 

DEVELOPING SITE-SPECIFIC CRITERIA 

When one or more of these stipulations is not true or when 

insufficient data are available, more evaluation is advisable. 

Again, consultation between wetland scientists and criteria 

experts might be helpful in prioritizing those wetland types for 

which additional protection, or additional research, might be 

needed for some chemicals. Once a priority list for further 

evaluation is established, an approach to obtaining the 

additional required data can be determined. It might be possible 

to group wetlands by type, and possibly by designated use, and 

then develop site-specific criteria for all wetlands of that type 

in the State. 

18 
SECTION 5 

EXAMPLE ANALYSES 

Evaluations of the applicability of the six criteria listed 

in Table 2 will be made for two sets of wetland data, including 

shallow marshes and prairie potholes. The analyses in these 

examples were made with limited data for each wetland type and 

are preliminary. They have been compiled to be used only as 

illustrations of the usefulness of this approach. 

EXAMPLE 1 

The first example is based on a wetland study taking place 

in southcentral Minnesota. The wetlands are being studied to 

evaluate the effects of disturbance on water quality, as well as 

the effects of pesticides on wetland communities. Therefore 

chemical and biological data have been collected." 

Classification 

The wetland study sites are primarily shallow marshes 

(freshwater palustrine, persistent emergent, semi-permanently or 

seasonally-flooded, according to Cowardin15), dominated by 

Phalaris (reed canary grass) and Typha (cattails), but also 

include a small number of wet meadow/seasonally-flooded wetlands, 

deep marsh, shrub/scrub + woody wetlands, and ponds. 

Steps 1 and 2: Identification of Cofactors and Comparison to 

Wetland Water Chemistry 

Cofactors are identified for criteria chemicals in Table 4. 

Some water quality characteristics averaged for 5 seasons for the 

Minnesota wetlands are summarized in Table 5. 

Although some water chemistry conditions in the shallow 

marshes were within the ranges of the aquatic toxicity testing 

conditions, others were exceeded (Table 3). Wetland values for 

pH were well within the 6.5-9.0 range allowed for testing, so 

criteria having pH as a possible cofactor affecting toxicity 

and/or biological availability should not be underprotective 

because of pH effects. As Table 4 shows, PCP, chromium (VI), 

zinc, and cyanide can be more toxic at low pH values, so a very 

19 
acidic wetland might require additional evaluation in regard to 

PH. The PCP criterion has an adjustment factor for pH, which 

indicates that enough suitable data are available to allow this 

relationship to be incorporated into the criterion. 

Hardness values were not available for these marshes, but 

were probably fairly low since alkalinity was low. Table 4 lists 

hardness as a cofactor for zinc and chromium (VI). Table 1 

reveals that the zinc criterion has an adjustment factor for 

hardness, so any effect of hardness on zinc toxicity and/or 

biological availability is already included in the criterion and 

does not have to be considered further. Chromium (VI) is more 

toxic at low alkalinity and hardness, but the criterion was 

derived using soft water and should be protective for the 

wetlands. 

Total organic carbon (TOC) was highly variable in the 

wetlands and generally well above the 5 mg/L limit for toxicity 

testing. However parathion and zinc, the two criteria with TOC 

cofactor effects, have reduced toxicity and/or biological 

availability at high levels of organic matter (Table 4), so 

criteria should be protective. 

Dissolved oxygen (DC) was highly variable in the wetlands 

and reached very low levels in late summer. The shallow waters 

of the marshes were extremely warm on hot summer days. Toxicity 

and/or biological availability is increased by low DO and high 

temperatures for PCBs, PCP, and cyanide. These relationships 

will require further evaluation. 

Step 3: Comparisons of Species Lists 

In Step 3, fish, invertebrates, and plants inhabiting the 

wetlands are compared to species used in testing each criterion. 

For these examples, only the acute toxicity lists have been 

consulted. A list of genera common to both the marshes and to 

the toxicity tests was compiled for each criterion. When 

identical species were not found, species from the same genus 

were compared to determine whether habitat requirements are 

suitable enough to include them as representative species for 

these wetlands. The shortened list of marsh species the same as, 

or similar to, species used for toxicity testing was examined to 

determine whether the minimum family requirements for acute 

toxicity tests could be met for each criterion. Table 6 contains 

a list of marsh genera that could be used to fulfill minimum 

family requirements for each criterion. Appendix A contains a 

list of the sources that have been consulted in making this 

comparison. 

20 
The aquatic species found in the Minnesota wetlands were 

fairly well-represented by the acute toxicity test species for 

the six chemicals used in this example. The percentages of total 

species tested that have not been found in these wetlands were 

below 50% for all six criteria (Table 7). Except for PCBs, for 

which no plant value is available, plant species tested 

overlapped with species occurring in the wetlands. The absence 

of salmonids in wetlands was the only consistent omission. 

Of all the species tested, the salmonids are the most 

sensitive to PCP and cyanide and are much more sensitive than 

most invertebrate species. The inclusion of highly sensitive 

salmonid data in the criteria calculations probably ensures that 

these two criteria are adequately protective when applied to 

wetlands not containing this sensitive family (not considering 

cofactor effects). It would perhaps be more important to 

consider the effects of the absence of salmonids in Minnesota 

marshes for criteria where salmonids are among the least 

sensitive species, including parathion and chromium (VI). In this 

case, the presence of salmonid toxicity data in the criterion 

calculation, despite their absence from the wetlands, could 

possibly cause the criterion to be less restrictive than is 

appropriate for the wetland. 

Salmonids do not occur in the wetlands included in this 

example. Three criteria were missing an additional required 

taxonomic group (from Table 6: PCBs, chromium (VI), and cyanide). 

There are certainly representatives of this taxonomic group 

(nonarthropod/nonchordate) inhabiting the wetlands, but the 

genera used for toxicity tests did not correspond to the wetland 

genera. These three criteria have the least species on the acute 

toxicity list, so there are less species to compare to, in 

relation to the other criteria (Table 7). Toxicity experts and 

wetland biologists might be able to fill some of these data gaps 

by reaching conclusions on the suitability of wetland species to 

fulfill the minimum family requirements. 

EXAMPLE 2 

This example is based on data for a number of oligosaline 

prairie pothole wetlands in southcentral North Dakota.19,20 

Oligosaline is defined as ranging from 0.5-5 g/kg salinity, or 

specific conductance of 800-8,000 μS/cm at 25° C.15 

The chemical types of the majority of wetlands used in this 

example include magnesium bicarbonate, magnesium sulfate, and 

sodium sulfate." 

21 
Wetlands included in this example are semipermanent (cover 

type 4 of the classification system develo ed by Stewart and 

Kantrud for the glaciated prairie region) 2P containing wet 

meadow, shallow marsh, and deep marsh. ClAssification of these 

wetlands based on the Cowardin system can be found in Kantrud et 

a1.20 

. . . 

. DS land 2. Identtiication of Cofpctors QDd Co-on to 

WetLgnd Water Chew 

Cofactors are identified for criteria chemicals in Table 4. 

Water quality data for the prairie pothole wetlands are 

summarized in Table 8. A comparison of water chemistry 

conditions for the prairie potholes with standard toxicological 

testing conditions (Table 3) reveals a number of differences. 

These wetlands are extremely alkaline and saline compared to 

water used for freshwater toxicity testing. Salinity (reported 

as specific conductance) can vary greatly over the year and is 

concentrated by the high rates of evaporation and transpiration 

that take place in the summer. A number of the wetlands have pH 

values above the 6.5-9.0 range that the criteria are designed to 

protect. No data were available for total organic carbon (TOC), 

but dissolved organic carbon values from other prairie pothole 

systems were general1 4; well above the TOC limit of 5 mg/L used 

for toxicity testing. As in Example 1, hardness can be 

eliminated from consideration as a cofactor, because toxicity 

and/or biological availability is decreased as hardness 

increases. Similarly, the probable high TOC levels would 

decrease toxicity and/or biological availability for zinc and 

chromium(V1). The high pH values should cause decreased toxicity 

and/or biological availability. Bioavailability of zinc is 

reduced in high ionic strength waters such as these. 

Dissolved oxygen (DO) levels drop in the winter and in 

middle to late summer, allowing anoxic conditions to develop. 

Although no aquatic temperature data were available, the Dakotas 

have moderately hot summers (mean July temperature of 22.3°C).20 

The shallow waters of the prairie potholes probably become very 

warm in late summer, corresponding with low DO levels. Toxicity 

and/or biological availability is increased by low DO and high 

temperatures for PCBs, PCP, and cyanide. These relationships 

will require further evaluation. 

Steb 3: Comndsons of Species Listg 

Semi-permanent prairie pothole wetlands are generally 

shallow and eutrophic. Water levels fluctuate greatly, as does 

22 
salinity. The cold winters can cause some of the wetlands to 

freeze to the bottom. Both winterkill and summerkill, caused by 

the effects of lack of oxygen, can occur. Fish can survive only 

in semipermanent wetlands that have connections to deeper water 

habitat. The only native fishes known to occur in semi-permanent 

prairie potholes are fathead minnow LXQW&LS) and 

brook stickleback (Culaeg inconstam 

The invertebrate taxa of prairie potholes are typical of 

other eutrophic, alkaline systems in the United States. 

Macroinvertebrate species assemblages are highly influenced by 

hydroperiod and salinity in these systems, and species diversity 

drops as salinity increases.20 Care must be taken in aggregating 

large salinity ranges into one wetland type (i.e. "oligosalinem 

may be too broad a class in terms of species representativeness). 

Comparisons of species typical of the wetlands with the criteria 

species lists reveals some major differences. For example, a 

large proportion of the aquatic insects tested for each criterion 

are found in flowing water, and therefore might not be 

characteristic of prairie pothole aquatic insects. Although many 

species of aquatic insects are found in these wetlands", there 

are not many suitable aquatic insects on the criteria species 

lists to compare to resident wetland species. Prairie pothole 

wetlands do not harbor Decapods (crayfish and shrimp), another 

common group for testing. Eubranchiopods (fairy, tadpole, and 

clam shrimp) are commonly found in prairie pothole wetlands", 

but only one representative of this group has been used to 

establish criteria, and that species was not on the list for any 

of the criteria used as examples here. Except for PCBs, for 

which no plant value is available, plant species tested do 

overlap with species occurring in the wetlands. Appendix B 

contains sources used in making comparisons. 

The above discussion has obvious implications for 

determining applicability of criteria based on suitability of 

species. As Table 7 shows, the percentages of species tested for 

each criterion that have not been found in prairie potholes are 

rather high (up to 67%). There are more gaps in the minimum 

family requirements for fish and chordates (Table 9) than were 

found for the Minnesota marsh example. The lack of fish in these 

wetlands dictates that amphibians or other chordates be used to 

fill these family requirements. The paucity of fish in these 

wetlands again has relevance to the protectiveness of the 

criteria. Fish are the most sensitive group tested for PCP and 

cyanide, so these criteria may have an added "buffer" of 

protection (in relation to the other criteria used as examples) 

when applied with no modifications to this wetland type. 

23 
SUMMARY OF THE EXAMPLE ANALYSES 

The conclusions discussed below should be considered as 

examples only. They should not be considered final for these 

wetland types. 

Cofactor Effects 

Based on this simple analysis, the only cofactors that 

potentially could cause criteria to be underprotective were DO 

and temperature. The low DO and high temperatures common in both 

wetland types in mid to late summer could cause increased 

toxicity and/or biological availability for PCBs, PCP, and 

cyanide. Cofactor effects for chromium (VI), zinc, and parathion 

were either not important under the chemical conditions 

encountered in these wetlands or should result in criteria being 

more, rather than less, protective for the wetland biota. Based 

on water quality characteristics, it can be concluded that 

chromium (VI), zinc, and parathion criteria are probably 

adequately protective of these wetland types with no acute 

modification. 

The importance of the DO and temperature relationship 

requires further evaluation for PCBs, PCP, and cyanide. Chemists 

and wetlands experts should be consulted and further literature 

reviews should be completed to evaluate the need for additional 

toxicity tests. If it is determined that a modification to a 

criterion is warranted, seasonal site-specific criteria might be 

appropriate in this case. The indicator species procedure could 

be used, requiring toxicity tests using site water on one fish 

and one invertebrate. The tests could be done at the high 

temperatures and low DO found in late summer in the wetlands. 

Species Comparisons 

The Salmonidae are a required family group for establishing 

a Final Acute Value and yet are not present in either of the 

wetland types used as examples. This evaluation is most 

concerned with ensuring that criteria are adequately protective, 

so the absence of this family in the wetlands should only be 

considered a problem if the unmodified criterion (which includes 

the Salmonidae) might be underprotective. This would most likely 

be true for parathion and chromium(W). 

For several criteria, some family requirements are not 

fulfilled because the available toxicity data for that taxonomic 

group do not include wetland species or genera ("NT" in Tables 6 

and 9). While this document made comparisons at the genus level, 

others have made comparisons at the family level to determine if 

the species listed in the criteria document is a member of a 

24 
family that exists at the site.16 Issues related to species 

comparisons should be addressed through discussion with criteria 

experts and wetlands ecologists and through further literature 

review. 

The absence of fish in prairie potholes to fill the "other 

chordates" category for cyanide, zinc, chromium (VI), and PCBs may 

warrant additional toxicity tests and site-specific 

modifications. The only other fish likely to be present in these 

wetlands is the brook stickleback (Culaea inconstans)20 which was 

not tested for any of the six criteria. No non-fish chordates 

were tested either, so no evaluation of the probable sensitivity 

of other chordates to these criteria can be made based on the 

criteria documents. 

If it is decided upon more rigorous evaluation that these 

differences in taxonomic groups warrant additional efforts and 

development of site-specific criteria, the recalculation 

procedure can be used. A suitable family, resident in the 

wetlands, can be added to the list to replace the Salmonidae 

and/or other missing groups, either through additional toxicity 

tests or by including additional available data. 

Further Evaluation 

This approach helps to prioritize wetland types and criteria 

for further evaluation. It was concluded that zinc, 

chromium (VI), and parathion criteria require no modification with 

regard to cofactor effects. PCBs, PCP, and cyanide, however, 

should be evaluated further in regard to the effects of high 

temperatures and low DO on toxicity, for both wetland types. The 

absence of salmonids may be most important for parathion and 

chromium (VI) in both wetland types. Further consideration should 

be given to the need for additional tests with chordates from 

prairie pothole wetlands for cyanide, zinc, chromium (VI) and 

PCBs, although there is no evidence to suggest that the absence 

of representative wetland chordates from the test species will 

result in underprotective criteria. 

This type of evaluation, done for a number of wetland types 

and criteria, can be combined with information on the types of 

pollutants that threaten particular wetland types. In this way 

wetland types requiring additional evaluation and perhaps 

eventually some additional toxicity testing for particular 

pollutants can be prioritized based on adequacy of existing 

criteria, potential threats to the system, and resources 

available for testing. These examples illustrate the need for 

wetland scientists to work closely with criteria experts. Expert 

judgement is needed to evaluate the significance of the gaps in 

the available data. 

25 
SECTION 6 

CONCLUSIONS 

The efficient use of limited resources dictates that 

criteria and standards for wetlands be developed by making good 

use of the wealth of data that has been accumulated for other 

surface waters. This report focused on the application of 

numeric aquatic life criteria to wetlands. The numeric aquatic 

life criteria are designed to protect aquatic life and their 

uses. The criteria are conservative, and for most wetland types 

are probably protective or overprotective. 

A simple, inexpensive evaluation technique has been proposed 

in this document for detecting wetland types that might be 

underprotected for some chemicals by existing criteria. The 

approach relies on information contained in criteria documents, 

data regarding species composition and water quality 

characteristics for the wetland types of interest, and 

consultation with experts. It is intended to be used as a 

screening tool for prioritizing those wetland types that require 

additional evaluations and research. 

Two tests of the approach demonstrated that it can be used 

to identify cases in which criteria might be underprotective, but 

further evaluation and close coordination among regulatory 

agencies, wetland scientists, and criteria experts are needed to 

determine when actual modifications to the criteria are 

necessary. 

Site-specific guidelines for modifying the numeric criteria 

should be appropriate for use on wetlands in cases where 

additional evaluations reveal that modifications are needed. The 

approach described in this document can be used to compile lists 

of the most commonly under-represented species and the most 

frequently encountered chemicals. Aquatic toxicity tests can 

then be conducted which would apply to a number of wetland types. 

Information obtained with this approach can be used to 

prioritize further evaluations and research, identify gaps in 

data, and make further testing more efficient, but has some 

limitations. It does not adequately address the importance of 

plants in wetland systems and applies only to the aquatic 

component of wetlands. It relies on species assemblage and water 

26 
quality data that are not available for some wetland types. For 

these reasons, a meeting of wetland scientists and criteria 

experts is recommended to discuss the need for this type of 

evaluation, the utility of this approach, and possible 

alternative approaches. 

The application of numeric criteria to wetlands is just one 

part of a large effort to develop wetland standards and criteria. 

The development of biocriteria, sediment criteria, and wildlife 

criteria will help to ensure that all components of the wetland 

resource are adequately protected. 

27 
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2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

U.S. Fish and Wildlife Service. 1984. An Overview of Major 

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Tiner, R.W., Jr. 1984. Wetlands of the United States: 

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39. Washington, D.C., 67p. 

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 

1979. Classification of Wetlands and Deepwater Habitats of 

the United States. FWS/OBS-79/31. U.S. Fish and Wildlife 

Service. 

Hansen, D.J., J. Cardin, L.R. Goodman, and G.M. Cripe. 

1985. Applicability of Site-Specific Water Quality Criteria 

Obtained Using the Resident Species Recalculation Option. 

Internal report, U.S. EPA, Narragansett, Rhode Island and 

Gulf Breeze, Florida. 

American Society for Testing Materials. 1988. Standard 

Guide for Conducting Acute Toxicity Tests with Fishes, 

Macroinvertebrates, and Amphibians. Standard E 729-88a, 

ASTM, Philadelphia, Pennsylvania. 

Detenbeck, N.E. 1990. Effects of Disturbance on WaterQuality Functions of Wetlands: Interim Progress Report: 

January 1990. Natural Resources Research Institute. 

Internal report submitted to U.S. EPA, Duluth, Minnesota. 

Swanson, G.A., T.C. Winter, V.A. Adomaitis, and J.W. 

LaBaugh. 1988. Chemical Characteristics of Prairie Lakes 

in South-central North Dakota - Their Potential for 

Influencing Use by Fish an Wildlife. U.S. Fish and wildlife 

Service Technical Report 18. 

Kantrud, H.A., G.L. Krapu, and G.A. Swanson. 1989. Prairie 

Basin Wetlands of the Dakotas: A Community Profile. U.S. 

Fish and Wildlife Service Biological Report 85(7.28). 

29 
21. Stewart, R.E., and H.A. Kantrud. 1971. Classification of 

Natural Ponds and Lakes in the Glaciated Prairie Region. 

U.S. Fish and Wildlife Service Resource Publication 92. 

57p. 

22. LaBaugh, J.W. 1989. Chemical Characteristics of Water in 

Northern Prairie Wetlands. Pages 56-90 In A.G. van der 

Valk, ed., Northern Prairie Wetlands. Iowa State University 

Press. 

30 
APPENDIX A 

SOURCES USED IN SPECIES HABITAT IDENTIFICATION 

FOR MINNESOTA MARSHES 

Fishes: 

Eddy, S., and J.C. Underhill. 1974. Northern Fishes. 3rd 

edition. University of Minnesota, Minneapolis. 

Nelson, J.S. 1984. Fishes of the World. 2nd edition. New 

York: John Wiley and Sons. 

Niering, W.A. 1987. Wetlands. New York: Alfred A. Knopf. 

Personal Communications: 

P. DeVore and C. Richards of the Natural Resources 

Research Institute, Duluth, Minnesota. 

G. Montz, Minnesota Dept. of Natural Resources. 

Macroinvertebrates: 

Nierinq, W.A. 1987. Wetlands. New York: Alfred A. Knopf. 

Pennak, R.W. 1978. Fresh-water Invertebrates of the United 

States. 2nd edition. New York: John Wiley and Sons. 

Williams, W.D. 1976. Freshwater Isopods (Asellidae) of 

North America. U.S. EPA, Cincinnati. 

Personal Communications: 

P. DeVore and A. Hershey of the Natural Resources 

Research Institute, Duluth, Minnesota. 

P. Mickelson of the University of Minnesota, Duluth. 

31 
APPENDIX B 

SOURCES USED IN SPECIES HABITAT IDENTIFICATION 

FOR PRAIRIE POTHOLES 

Fishes: 

Kantrud, H.A., G.L. Krapu, and G.A. Swanson. 1989. Prairie 

Basin Wetlands of the Dakotas: A Community Profile. U.S. 

Fish and Wildlife Service Biological Report 85(7.28). 

Swanson, G.A., T.C. Winter, V.A. Adomaitis, and J.W. 

LaBaugh. 1988. Chemical Characteristics of Prairie Lakes 

in South-central North Dakota - Their Potential for 

Influencing Use by Fish an Wildlife. U.S. Fish and Wildlife 

Service Technical Report 18. 

Macroinvertebrates: 

Broschart, M.R. and R.L Linder. 1986. Aquatic 

invertebrates in level ditches and adjacent emergent marsh 

in a South Dakota wetland. Prairie Nat. 18(3):167-178. 

Eddy, S. and A.C. Hodson. 1961. Taxonomic Keys to the 

Common Animals of the Northcentral States. Minneapolis: 

Burgess Publishing Co. 

Krapu, G.L. 1974. Feeding ecology of pintail hens during 

reproduction. The Auk 91:278-290. 

Pennak, R.W. 1978. Fresh-water Invertebrates of the United 

States. 2nd edition. New York: John Wiley and Sons. 

Swanson, G.A. 1984. Invertebrates consumed by dabbling 

ducks (Anatinae) on the breeding grounds. Journal of the 

Minnesota Academy of Science 50:37-45. 

van der Valk, A., ed. 1989. Northern Prairie Marshes. 

Ames: Iowa State University Press. 

32 
TABLE 1. FRESHWATER NUMERIC AQUATIC LIFE CRITERIA* 

Chemical 

H, T, or pH** 

Dependent Chemical 

H, T, or pH** 

Dependent 

Organochlorines: 

Aldrin 

Chlordane 

DDT 

Dieldrin 

Endosulfan 

Endrin 

Heptachlor 

Lindane 

PCBs 

Pentachlorophenol 

Organophosphates: 

Chlorpyrifos 

Parathion 

PH 

Metals: 

Aluminum 

Arsenic (III) 

Cadmium 

Chromium (III) 

Chromium (VI) 

Copper 

Lead 

Mercury 

Nickel 

Selenium 

Silver 

Zinc 

Others: 

Ammonia 

Chloride 

Chlorine 

Cyanide 

Dissolved oxygen 

H 

H 

H 

H 

H 

H 

H 

PH, T 

T 

* Summarized from individual criteria documents. Chemicals 

that have adjustment factors built into the criteria are 

indicated. 

** H= Hardness, T = Temperature. 

33 
TABLE 2. SUITABILITY OF WETLAND SPECIES TO FILL MINIHUH FAMILY 

REQUIREMENTS FOR SIX CRITERION CHEMICALS 

Required 

Taxonomic 

Group 

Para- ChromPCBs thion PCP Cyanide Zinc ium(VI) 

Salmonid NP* NP NP NP NP NP 

Other Fish Y . . Y Y Y Y Y 

Other 

Chordate Y Y Y Y Y Y 

Planktonic 

Crustacean Y Y Y Y Y Y 

Benthic 

Crustacean Y Y Y Y Y Y 

Insect Y Y Y Y Y Y 

NonarthropodNonchordate NT*** Y Y Y Y Y 

Another 

Insect Y Y Y NT Y Y 

or New Phylum 

l NP Not present: Taxonomic group not present in most wetland 

types. 

**y Wetland genera represented adequately. 

***NT Not tested: Available toxicity data does not include 

sufficient wetland species. 

34 
TABLE 3. SOME CONDITIONS RECOMMENDED FOR DILUTION WATER 

FOR WATER QUALITY CRITERIA TESTING" 

Characteristic Freshwater Saltwater 

Total organic carbon <5 mg/L ~20 mg/L' 

Particulate matter <5 mq/L ~20 mg/L' 

PH 6.5-9.0 Stenohaline 8.0 

Euryhaline 7.7 

Range ~0.2 

Hardness 

(mg/L as CaC03) 

Salinity 

Soft water 40-48 

Range ~5 mg/Lb 

Stenohaline 34 g/kg 

Euryhaline 17 q/W 

Range ~2 g/kg' 

Dissolved oxygen 60-100% saturationd 60-100% saturationd 

Temperature +/- 5 OC of water' 

of origin 

' ~5 mg/L for tests other than saltwater bivalve molluscs. 

b Or 10% of average, whichever is higher. 

' Or 20% of average, whichever is higher. 

d For flow-through tests (40-100% for static tests). 

l For invertebrates only. 

35 
TABLB 4. BrrBCTB or cformrom3 OH CRITBRIOM CEBMICAL TOXICITY 

Corwroast Bffoat of Qreator Value 

PH Tot TIJRB TRW DO l? IONIC B BKJTR/ORQ 

Organoahlorines: 

Aldrin 

Chlordane 

DDT 

Dieldrin 

Endrin 

Heptachlor 

Lindane 

Endosulfan 

PCBs 

Pentachlorophenol 

Toxaphene 

+ + + 

+ 0 

+ - 

+ - 

+ 

Organophoaphatos: 

Parathion 

Chlorpyrifos 

not81#: 

Arsenic (III) 

ium 

L. 

nium (VI) 

,mium (III) 

Copper 

Lead 

Mercury 

Nickel 

Selenium 

Silver 

Zinc 

Aluminum 

+ + 

7 0 

+ 

+ - 

+ 

+ 

Other: 

Chlorine 

Cyanide 

Ammonia 

Chloride 

Do 

0 

+ 

0 

-? 

3 

0 

0 

+ - - 

+ - 

+? 

+: increased toxicity/mobility ?: tested and found inconclusive 

0: no effect on toxicity/mobility : not discussed in criteria document 

-t decreased toxicity/mobility +: short-term increase/long-term decrease 

TOC: total organic carbon DO: dissolved oxygen H: hardness 

TURB: turbidity NUTR/ORG: nutrients/organic acids 

m* -. ionic strength/cations S: salinity 

36 
TABLE 5. WATER CHEMISTRY FOR SELECTED MINNESOTA MARSHES. 

Water Quality 

Characteristic Mean Value 

Comparison with 

Standard Testing 

Range Conditions 

pH (pH units) 

Total organic 

carbon (mg/L) 

Dissolved 

oxygen (w/L) 

Hardness 

(mg/L as CaCO,) 

Alkalinity 

(mg/L as CaCO,) 

Temperature ("C) 

Turbidity (NTU) 

7.1 

20 

8.2 

No data 

6.1 - 7.6 Within range 

5 - 60 High 

0.4 - 15.4 Seasonally low 

8 4 - 14 

11.9 0.3 - 31.0 Seasonal extremes 

33 1 - 412 

l Data taken from Detenbeck (1990), n=42 wetlands.18 

37 
TABLE 6. COMPARISON OF TEST SPECIES WITH 

MINNESOTA MARSH BIOTA FOR SIX CRITERIA 

Required 

Taxonomic 

Group 

PCBs Parathion PCP 

Salmonid Npd NP NP 

Other Fish' Micropterus Lepomis Micropterus 

Other 

Chordate Pimephales Pimephales Rana 

Planktonic 

Crustacean Daphnia Daphnia Daphnia 

Benthic 

Crustacean 

unknown 

amphipod Orconectes Orconectes 

Insect Ishnurab Chironomus Tanytarsus 

Nonarthropod- unknownC unknow+ 

Nonchordate NTe nematodes/ nematodes/ 

annelids annelids 

Another unknown 

Insect Tanytarsus Ishnura amphipod/ 

or New Phylum isopod 

Aquatic 

Plant NT alga Lemna 

continued 

38 
TABLE 6, CONTINUED 

Required 

Taxonomic 

Group 

Cyanide Zinc Chromium(V1) 

Salmonid NP 

Other Fish' Perca 

Other 

Chordate Lepomis 

Planktonic 

Crustacean Daphnia 

Benthic 

Crustacean 

unknownC 

amphipod/ 

isopod 

Insect Tanytarsus 

NonarthropodNonchordate Physa 

Another 

Insect 

or New Phylum 

NT 

Aquatic 

Plant Lemna 

NP 

Lepomis 

Pimephales 

Daphnia 

unknownc 

amphipod/ 

isopod 

Argiab 

Physa 

unknownC 

annelid/ 

nematode 

Lemna 

NP 

Lepomis 

Pimephales 

Daphnia 

Orconectes 

Chironomus 

Physa 

NT 

alga 

a Fish were sampled in water bodies associated with some of 

the wetlands, not in the wetlands themselves. 

b Probable or seen as an adult. 

C Unknown species from these taxa found in wetlands. May or 

may not be similar in terms of habitat requirements, etc. to 

species used in toxicity tests. 

d Not present: Taxonomic group not present in wetland type. 

e Not tested: Available toxicity data does not include 

sufficient wetland species. 

39 
TABLE 7. NUMBER OF SPECIES TESTED FOR ACUTE CRITERIA AND 

PERCENTAGE OF TEST SPECIES THAT ARE NOT FOUND IN 

MINNESOTA MARSHES OR OLIGOSALINE PRAIRIE POTHOLES* 

Species Used to Not Present Not Present in 

Chemical Establish FAV" in Marshes Prairie Potholes 

(Total Number) (Per cent) (Per cent) 

PCBs 10 30% 40% 

Parathion 37 43% 64% 

PCP 37 22% 43% 

Cyanide 17 29% 65% 

Zinc 45 45% 67% 

Chromium(V1) 33 27% 64* 

t Remainder of percentage includes both those species that are 

known to occur in these wetlands and those species that may 

occur in the wetlands, but insufficient data are available. 

l + Final Acute Value. 

40 
TABLE 8. WATER QUALITY CHARACTERISTICS FOR 

OLIGOSALINE PRAIRIE POTHOLES' 

Water Quality 

Characteristic Mean Value 

Comparison with 

Standard Testing 

Range Conditions 

pH (pH units) 8.9 7.4 - 10.3b High 

Total organic 

carbon (mg/L) No data' 

Dissolved 

oxygen (wm) No datad 

Hardness No data' 

(mg/L as CaC03) 

Alkalinity 

(mg/L as CaCO,) 

650 230 - 1300 High 

Temperature ("C) No data‘ 

Specific conductance 3568 750 - 8000 

(bS/cm at 25'C) 

;: 

Data summarized from Swanson et al. (1988)." 

N=27 wetlands. 

C Dissolved organic carbon data for Manitoba prairie potholes 

ranged from 0.4-102 mg/L, and for Nebraska, from 20-60 mg/L 

in one study and 139-440 mg/L in another study.22 

d Winterkill, caused by low dissolved oxygen under ice, occurs 

in many of these lakes. 

e An estimate of hardness based on alkalinity values gives a 

mean of 760 mg/L as CaCO. 

f Region is characterized b y very cold winters and warm 

summers. 

41 
TABLE 9. COMPARISON OF TEST SPECIES WITH 

PRAIRIE POTHOLE BIOTA FOR SIX CRITERIA 

Required 

Taxonomic 

Group 

PCBs Parathion PCP 

Salmonid NP NP NP 

Other Fish Pimephales Pimephales Pimephales 

Other 

Chordate NT Pseudacris' Rana' 

Planktonic 

Crustacean Daphnia Daphnia Daphnia 

Benthic 

Crustacean Gammarus' Gammarud Hyalella 

Insect damselflyb Peltodytes Tanytarsusb 

Nonarthropod- tubificid tubificid 

Nonchordate NT WOrmb WOrmb 

Another 

Insect Tanytarsusb Chironomus Physa 

or New Phylum 

Aquatic 

Plant NT Microcystis Lemna 

42 
TABLE 9, CONTINUED 

Required 

Taxonomic 

Group 

Cyanide Zinc Chromium(V1) 

Salmonid 

Other Fish 

Other 

Chordate 

Planktonic 

Crustacean 

Benthic 

Crustacean 

Insect 

NonarthropodNonchordate 

Another 

Insect 

or New Phylum 

Aquatic 

Plant 

NP 

Pimephales 

NP 

Pimephales 

NT NT 

Daphnia 

Gammarus' 

Tanytarsusb 

Physa' 

NT 

Lemna 

Daphnia 

Gammartd 

Argiab 

Physa' 

tubificid 

wormb 

Lemma 

NP 

Pimephales 

NT 

Daphnia 

Hyalella 

Chironomus' 

Physa' 

damselflyb 

Nitzschia 

;: 

Genus is present in the wetlands; may not be same species. 

Species representative of that taxonomic group from criteria 

testing lists probably present in prairie potholes, but no 

actual data available. 

43