PB85-227049 

Guidelines for Deriving 

Numerical National Water Quality Criteria 

for the Protection Of Aquatic Organisms 

and Their Uses 

by Charles E. Stephen, Donald I. Mount, David J. Hansen, 

John R. Gentile, Gary A. Chapman, and William A. Brungs 

Office of Research and Development 

Environmental Research Laboratories 

Duluth, Minnesota 

Narragansett, Rhode Island 

Corvallis, Oregon 
Notices 

This document has been reviewed in accordance with U.S. Environmental Protection Agency 

policy and approved for publication. 

Mention of trade names or commercial products does not constitute endorsement or 

recommendation for use. 

This document is available the public to through the National Technical Information Service 

(NTIS), 5285 Port Royal Road, Springfield, VA 22161. 

 Special Note 

This December 2010 electronic version of the 1985 Guidelines serves to meet the requirements of Section 

508 of the Rehabilitation Act. While converting the 1985 Guidelines to a 508-compliant version, EPA 

updated the taxonomic nomenclature in the tables of Appendix 1 to reflect changes that occurred since the 

table were originally produced in 1985. The numbers included for Phylum, Class and Family represent 

those currently in use from the Integrated Taxonomic Information System, or ITIS, and reflect what is 

referred to in ITIS as Taxonomic Serial Numbers. ITIS replaced the National Oceanographic Data Center 

(NODC) taxonomic coding system which was used to create the original taxonomic tables included in the 

1985 Guidelines document (NODC, Third Addition - see Introduction). For more information on the 

NODC taxonomic codes, see http://www.nodc.noaa.gov/General/CDR-detdesc/taxonomic-v8.html. 

The code numbers included in the reference column of the tables have not been updated from the 1985 

version. These code numbers are associated with the old NODC taxonomic referencing system and are 

simply replicated here for historical purposes. Footnotes may or may not still apply. 

EPA is working on a more comprehensive update to the 1985 Guidelines, including new taxonomic tables 

which better reflect the large number of aquatic animal species known to be propagating in U.S. waters. 

ii 
Table of Contents 

Notices ___________________________________________________________________ ii 

Table of Contents ___________________________________________________________iii 

Executive Summary _________________________________________________________ iv 

Figure 1 ___________________________________________________________________ v 

Introduction________________________________________________________________ 1 

I. Definition of Material of Concern _______________________________________ 9 

II. Collection of Data___________________________________________________ 11 

III. Required data ______________________________________________________ 11 

IV. Final Acute Value ___________________________________________________ 14 

V. Final Acute Equation ________________________________________________ 17 

VI. Final Chronic Value _________________________________________________ 19 

VII. Final Chronic Equation_______________________________________________ 22 

VIII. Final Plant Value____________________________________________________ 25 

IX. Final Residue Value _________________________________________________ 25 

X. Other Data_________________________________________________________ 28 

XI. Criterion __________________________________________________________ 28 

XII. Final Review _______________________________________________________ 29 

References________________________________________________________________ 31 

Appendix 1. Resident North American Species of Aquatic Animals Used in Toxicity and 

Bioconcentation Tests_______________________________________________________ 33 

Introduction_____________________________________________________________ 33 

Freshwater Species Table __________________________________________________ 34 

Footnotes for Freshwater Species ____________________________________________ 42 

References for Freshwater Species ___________________________________________ 43 

Saltwater Species Table ___________________________________________________ 45 

Footnotes for Saltwater Species _____________________________________________ 51 

References for Saltwater Species ____________________________________________ 51 

Appendix 2. Example Calculation of Final Acute Value, Computer Program, and Printouts 53 

A. Example Calculation_________________________________________________ 53 

B. Example Computer Program in BASIC Language for Calculating the FAV______ 53 

C. Example Printouts from Program _______________________________________ 54 

iii 
Executive Summary 

Derivation of numerical national water quality criteria for the protection of aquatic organism and 

their uses is a complex process (Figure 1) that uses information from many areas of aquatic 

toxicology. After a decision is made that a national criterion is needed for a particular material, 

all available information concerning toxicity to, and bioaccumulation by, aquatic organisms is 

collected, reviewed for acceptability, and sorted. If enough acceptable data on acute toxicity to 

aquatic animals are available, they are used to estimate the highest one-hour average 

concentration that should not result in unacceptable effects on aquatic organisms and their uses. 

If justified, this concentration is made a function of a water quality characteristic such as pH, 

salinity, or hardness. Similarly, data on the chronic toxicity of the material to aquatic animals are 

used to estimate the highest four-daily average concentration that should not cause unacceptable 

toxicity during a long-term exposure. If appropriate, this concentration is also related to a water 

quality characteristic. 

Data on toxicity to aquatic plants are examined to determine whether plants are likely to be 

unacceptably affected by concentrations that should not cause unacceptable effects on animals. 

Data on bioaccumulation by aquatic organisms are used to determine if residues might subject 

edible species to restrictions by the U.S. Food and Drug Administration or if such residues might 

harm some wildlife consumers of aquatic life. All other available data are examined for adverse 

effects that might be biologically important. 

If a thorough review of the pertinent information indicates that enough acceptable data are 

available, numerical national water quality criteria are derived for fresh water or salt water or 

both to protect aquatic organisms and their uses from unacceptable effects due to exposures to 

high concentrations for short periods of time, lower concentrations for longer periods of time, 

and combinations of the two. 

iv 
Figure 1 

Derivation of Numerical National Water Quality Crtieria for the Protection of Aquatic Organisms and Their 

Uses 

Acute 

Toxicity to 

Animals

Bioaccumulation

Other Data

Chronic 

Toxicity to 

Animals

Toxicity to 

Plants

Final Acute 

Value 

Final 

Residue 

Value 

Lowest 

Biologically 

Important 

Value 

Final 

Chronic 

Value 

Final Plant 

Value 

Criterion 

Maximum 

Concentration

Criterion 

Continuous 

Concentration 

Review for 

Completeness 

of Data and 

Appropriateness 

of Results 

National Criterion 

Collect and 

Review 

Data

v 
Introduction 

Of the several possible forms of criteria, the numerical form is the most common, but the 

narrative (e.g., pollutants must not be present in harmful concentrations) and operational (e.g., 

concentrations of pollutants must not exceed one-tenth of the 96-hr LC50) forms can be used if 

numerical criteria are not possible or desirable. If it were feasible, a freshwater (or saltwater) 

numerical aquatic life national criterion*

 for a material should be determined by conducting field 

tests on a wide variety of unpolluted bodies of fresh (or salt) water. It would be necessary to add 

various amounts of the material to each body of water in order to determine the highest 

concentration that would not cause any unacceptable long-term or short-term effect on the 

aquatic organisms or their uses. The lowest of these highest concentrations would become the 

freshwater (or saltwater) national aquatic life water quality criterion for that material, unless one 

or more of the lowest concentrations were judged to be outliers. Because it is not feasible to 

determine national criteria by conducting such field tests, these Guidelines for Deriving 

Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their 

Uses (hereafter referred to as the National Guidelines) describe an objective, internally 

consistent, appropriate, and feasible way of deriving national criteria, which are intended to 

provide the same level of protection as the infeasible field testing approach described above. 

Because aquatic ecosystems can tolerate some stress and occasional adverse effects, protection 

of all species at all times and places is not deemed necessary. If acceptable data are available for 

a large number of appropriate taxa from an appropriate variety of taxonomic and functional 

groups, a reasonable level of protection will probably be provided if all except a small fraction of 

the taxa are protected, unless a commercially or recreationally important species is very 

sensitive. The small fraction is set at 0.05 because other fractions resulted in criteria that seemed 

too high or too low in comparison with the sets of data from which they were calculated. Use of 

0.05 to calculate a Final Acute Value does not imply that this percentage of adversely affected 

taxa should be used to decide in a field situation whether a criterion is too high or too low or just 

right. 

Determining the validity of a criterion derived for a particular body of water, possibly by 

modification of a national criterion to reflect local conditions 1, 2, 3

, should be based on an 

operation definition of "protection of aquatic organisms and their uses" that takes into account 

the practicalities of field monitoring programs and the concerns of the public. Monitoring 

programs should contain sampling points at enough times and places that all unacceptable 

changes, whether caused directly or indirectly, will be detected. The programs should adequately 

monitor the kinds of species of concern to the public, i.e., fish in fresh water and fish and 

macroinvertebrates in salt water. If the kinds of species of concern cannot be adequately 

monitored at a reasonable cost, appropriate surrogate species should be monitored. The kinds of 

species most likely to be good surrogates are those that either (a) are a major food of the desired 

kinds of species or (b) utilize the same food as the desired species or (c) both. Even if a major 

adverse effect on appropriate surrogate species does not directly result in an unacceptable effect 

on the kinds of species of concern to the public, it indicates a high probability that such an effect 

will occur. 

 

*

 The term "national criteria" is used herein because it is more descriptive than the synonymous term "section 304(a) 

criteria", which is used in the Water Quality Standards Regulation [1]. 

1 
To be acceptable to the public and useful in field situations, protection of aquatic organisms and 

their uses should be defined as prevention of unacceptable long-term short-term effects on (1) 

commercially, recreationally, and other important species and (2) (a) fish and benthic 

invertebrate assemblages in rivers and streams, and (b) fish, benthic invertebrate, and 

zooplankton assemblages in lakes, reservoirs, estuaries, and oceans. Monitoring programs 

intended to be able to detect unacceptable effects should be tailored to the body of water of 

concern so that necessary samples are obtained at enough times and places to provide adequate 

data on the populations of the important species, as well as data directly related to the reasons for 

their being considered important. For example, for substances that are residue limited, species 

that are consumed should be monitored for contaminants to ensure that wildlife predators are 

protected, FDA action levels are not exceeded, and flavor is not impaired. Monitoring programs 

should also provide data on the number of taxa and number of individuals in the above-named 

assemblages that can be sampled at reasonable cost. The amount of decrease in the number of 

taxa or number of individuals in an assemblage that should be considered unacceptable should 

take into account appropriate features of the body of water and its aquatic community. Because 

most monitoring programs can only detect decreases of more than 20 percent, any statistically 

significant decrease should usually be considered unacceptable. The insensitivity of most 

monitoring programs greatly limits their usefulness for studying the validity of criteria because 

unacceptable changes can occur and not be detected. Therefore, although limited field studies 

can sometimes demonstrate that criteria are underprotective, only high quality field studies can 

reliably demonstrate that criteria are not underprotective. 

If the purpose of water quality criteria were to protect only commercially and recreationally 

important species, criteria specifically derived to protect such species and their uses from the 

direct adverse effects of a material would probably, in most situations, also protect those species 

from indirect adverse effects due to effects of the material on other species in the ecosystem. For 

example, in most situations either the food chain would be more resistant than the important 

species and their uses or the important species and their food chains would be adaptable enough 

to overcome effects of the material on portions of the food chains. 

These National Guidelines 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, such as the Great 

Salt Lake, brine shrimp, and the siscowet subspecies of lake trout, which occurs in Lake Superior 

and contains up to 67% fat in the fillets 4

. Derivation of criteria specifically for the Great Salt 

Lake or Lake Superior might have to take brine shrimp and siscowet, respectively, into account. 

Numerical aquatic life criteria derived using these National Guidelines are expressed as two 

numbers, rather than the traditional one number, so that the criteria more accurately reflect 

toxicological and practical realities. If properly derived and used, the combination of a maximum 

concentration and a continuous concentration should provide an appropriate degree of protection 

of aquatic organisms and their uses from acute and chronic toxicity to animals, toxicity to plants, 

and bioaccumulation by aquatic organisms, without being as restrictive as a one-number criterion 

would have to be in order to provide the same degree of protection. 

Criteria produced by these Guidelines are intended to be useful for developing water quality 

standards, mixing zone standards, effluent limitations, etc. The development of such standards 

2 
and limitations, however, might have to take into account such additional factors as social, legal, 

economic, and hydrological considerations, the environmental and analytical chemistry of the 

material, the extrapolation from laboratory data to field situations, and relationships between 

species for which data are available and species in the body of water of concern. As an 

intermediate step in the development of standards, it might be desirable to derive site-specific 

criteria by modification of national criteria to reflect such local conditions as water quality, 

temperature, or ecologically important species 1, 2. 3

. In addition, with appropriate modifications 

these National Guidelines can be used to derive criteria for any specific geographical area, body 

of water (such as the Great Salt Lake), or group of similar bodies of water, if adequate 

information is available concerning the effects of the material of concern on appropriate species 

and their uses. 

Criteria should attempt to provide a reasonable and adequate amount of protection with only a 

small possibility of considerable overprotection or underprotection. It is not enough that a 

national criterion be the best estimate that can be obtained using available data; it is equally 

important that a criterion be derived only if adequate appropriate data are available to provide 

reasonable confidence that it is a good estimate. Therefore, these National Guidelines specify 

certain data that should be available if a numerical criterion is to be derived. If all the required 

data are not available, usually a criterion should not be derived. On the other hand, the 

availability of all required data does not ensure that a criterion can be derived. 

A common belief is that national criteria are based on "worst case" assumptions and that local 

considerations will raise, but not lower, criteria. For example, it will usually be assumed that if 

the concentration of a material in a body of water is lower than the national criterion, no 

unacceptable effects will occur and no site-specific criterion needs to be derived. If, however, the 

concentration of a material in a body of water is higher than the national criterion, it will usually 

be assumed that a site-specific criterion should be derived. In order to prevent the assumption of 

the "worst case" nature of national criteria from resulting in the underprotection of too many 

bodies of water, national criteria must be intended to protect all or almost all bodies of water. 

Thus, if bodies of water and the aquatic communities in them do differ substantially in their 

sensitivities to a material, national criteria should be at least somewhat overprotective for a 

majority of the bodies of water. To do otherwise would either (a) require derivation of sitespecific criteria even if the site-specific concentration were substantially below the national 

criterion or (b) cause the "worst case" assumption to result in the underprotection of numerous 

bodies of water. On the other hand, national criteria are probably underprotective of some bodies 

of water. 

The two factors that will probably cause the most difference between national and site-specific 

criteria are the species that will be exposed and the characteristics of the water. In order to ensure 

that national criteria are appropriately protective, the required data for national criteria include 

some species that are sensitive to many materials and national criteria are specifically based on 

tests conducted in water relatively low in particulate matter and organic matter. Thus, the two 

factors that will usually be considered in the derivation of site-specific criteria from national 

criteria are used to help ensure that national criteria are appropriately protective. 

On the other hand, some local conditions might require that site-specific criteria be lower than 

national criteria. Some untested locally important species might be very sensitive to the material 

of concern, and local water quality might not reduce the toxicity of the material. In addition, 

3 
aquatic organisms in field situations might be stressed by diseases, parasites, predators, other 

pollutants, contaminated or insufficient food, and fluctuating and extreme conditions of flow, 

water quality, and temperature. Further, some materials might degrade to more toxic materials, 

or some important community functions or species interactions might be adversely affected by 

concentrations lower than those that affect individual species. 

Criteria must be used in a manner that is consistent with the way in which they were derived if 

the intended level of protection is to be provided in the real world. Although derivation of water 

quality criteria for aquatic life is constrained by the ways toxicity and bioconcentration tests are 

usually conducted, there are still many different ways that criteria can be derived, expressed, and 

used. The means used to derive and state criteria should relate, in the best possible way, the kinds 

of data that are available concerning toxicity and bioconcentration and the ways criteria can be 

used to protect aquatic organisms and their uses. 

The major problem is to determine the best way that the statement of a criterion can bridge the 

gap between the nearly constant concentrations used in most toxicity and bioconcentration tests 

and the fluctuating concentrations that usually exist in the real world. A statement of a criterion 

as a number that is not to be exceeded any time or place is not acceptable because few, if any, 

people who use criteria would take it literally and few, if any, toxicologists would defend a literal 

interpretation. Rather than try to reinterpret a criterion that is neither useful nor valid, it is better 

to develop a more appropriate way of stating criteria. 

Although some materials might not exhibit thresholds, many materials probably do. For any 

threshold material, continuous exposure to any combination of concentrations below the 

threshold will not cause an unacceptable effect (as defined on pages 1 and 2) on aquatic 

organisms and their uses, except that the concentration of a required trace nutrient might be too 

low. However, it is important to note that this is a threshold of unacceptable effect, not a 

threshold of adverse effect. Some adverse effect, possibly even a small reduction in the survival, 

growth, or reproduction of a commercially or recreationally important species, will probably 

occur at, and possibly even below, the threshold. The Criterion Continuous Concentration (CCC) 

is intended to be a good estimate of this threshold of unacceptable effect. If maintained 

continuously, any concentration above the CCC is expected to cause an unacceptable effect. On 

the other hand, the concentration of a pollutant in a body of water can be above the CCC without 

causing an unacceptable effect if (a) the magnitudes and durations of the excursions above the 

CCC are appropriately limited and (b) there are compensating periods of time during which the 

concentration is below the CCC. The higher the concentration is above the CCC, the shorter the 

period of time it can be tolerated. But it is unimportant whether there is any upper limit on 

concentrations that can be tolerated instantaneously or even for one minute because 

concentrations outside mixing zones rarely change substantially in such short periods of time. 

An elegant, general approach to the problem of defining conditions (a) and (b) would be to 

integrate the concentration over time, taking into account uptake and depuration rates, transport 

within the organism to a critical site, etc. Because such an approach is not currently feasible, an 

approximate approach is to require that the average concentration not exceed the CCC. The 

average concentration should probably be calculated as the arithmetic average rather than the 

geometric mean 5

. If a suitable averaging period is selected, the magnitudes and durations of 

concentrations above the CCC will be appropriately limited, and suitable compensating periods 

below the CCC will be required. 

4 
In the elegant approach mentioned above, the uptake and depuration rates would determine the 

effective averaging period, but these rates are likely to vary from species to species for any 

particular material. Thus the elegant approach might not provide a definitive answer to the 

problem of selecting an appropriate averaging period. An alternative is to consider that the 

purpose of the averaging period is to allow the concentration to be above the CCC only if the 

allowed fluctuating concentrations do not cause more adverse effect than would be caused by a 

continuous exposure to the CCC. For example, if the CCC caused a 10% reduction in growth of 

rainbow trout, or a 13% reduction in survival of oysters, or a 7% reduction in reproduction of 

smallmouth bass, it is the purpose of the averaging period to allow concentrations above the 

CCC only if the total exposure will not cause any more adverse effect than continuous exposure 

to the CCC would cause. 

Even though only a few tests have compared the effects of a constant concentration with the 

effects of the same average concentration resulting from a fluctuating concentration, nearly all 

the available comparisons have shown that substantial fluctuations result in increased adverse 

effects 5, 6

. Thus if the averaging period is not to allow increased adverse effects, it must not 

allow substantial fluctuations. Life-cycle tests with species such as mysids and daphnids and 

early life-stage tests with warmwater fishes usually last for 20 to 30 days. An averaging period 

that is equal to the length of the test will obviously allow the worst possible fluctuations and 

would very likely allow increased adverse effects. 

An averaging period of four days seems appropriate for use with the CCC for two reasons. First, 

it is substantially shorter than the 20 to 30 days that is obviously unacceptable. Second, for some 

species it appears that the results of chronic tests are due to the existence of a sensitive life stage 

at some time during the test 7

, rather than being caused by either long-term stress or long-term 

accumulation of the test material in the organism. The existence of a sensitive life stage is 

probably the cause of acute-chronic ratios that are not much greater than 1, and is also possible 

when the ratio is substantially greater than 1. In addition, some experimentally determined acutechronic ratios are somewhat less than 1, possibly because prior exposure during the chronic test 

increased the resistance of the sensitive life stage 8. A four-day averaging period will probably 

prevent increased adverse effects on sensitive life stages by limiting the durations and 

magnitudes of exceedences*

 of the CCC. 

The considerations applied to interpretation of the CCC also apply to the CMC. For the CMC the 

averaging period should again be substantially less than the lengths of the tests it is based on, i.e., 

substantially less than 

48 to 96 hours. One hour is probably an appropriate averaging period because high 

concentrations of some materials can cause death in one to three hours. Even when organisms do 

not die within the first hour or so, it is not known how many might have died due to delayed 

effects of this short of an exposure. Thus it is not appropriate to allow concentrations above the 

CMC to exist for as long as one hour. 

The durations of the averaging periods in national criteria have been made short enough to 

restrict allowable fluctuations in the concentration of the pollutant in the receiving water and to 

restrict the length of time that the concentration in the receiving water can be continuously above 

 

*

 Although "exceedence" has not been found in any dictionary, it is used here because it is not appropriate to use 

"violation" in conjunction with criteria, no other word seems appropriate, and all appropriate phrases are awkward. 

5 
a criterion concentrations. The statement of a criterion could specify that the four-day average 

should never exceed the CCC and that the one-hour average should never exceed the CMC. 

However, one of the most important uses of criteria is for designing waste treatment facilities. 

Such facilities are designed based on probabilities and it is not possible to design for a zero 

probability. Thus, one of the important design parameters is the probability that the four-day 

average or the one-hour-average will be exceeded, or, in other words, the frequency with which 

exceedences will be allowed. 

The frequency of allowed exceedences should be based on the ability of aquatic ecosystems to 

recover from the exceedences, which will depend in part on the magnitudes and durations of the 

exceedences. It is important to realize that high concentrations caused by spills and similar major 

events are not what is meant by an "exceedence", because spills and other accidents are not part 

of the design of the normal operation of waste treatment facilities. Rather, exceedences are 

extreme values in the distribution of ambient concentrations and this distribution is the result of 

the usual variations in the flows of both the effluent and the receiving water and the usual 

variations in the concentrations of the material of concern in both the effluent and in the 

upstream receiving water. Because exceedences are the result of usual variation, most of the 

exceedences will be small and exceedences as large as a factor of two will be rare. In addition, 

because these exceedences are due to random variation, they will not be evenly spaced. In fact, 

because many receiving waters have both one-year and multi-year cycles and many treatment 

facilities have daily, weekly, and yearly cycles, exceedences will often be grouped, rather than 

being evenly spaced or randomly distributed. If the flow of the receiving water is usually much 

greater than the flow of the effluent, normal variation and the flow cycles will result in the 

ambient concentration usually being below the CCC, occasionally being near the CCC, and 

rarely being above the CCC. In addition, exceedences that do occur will be grouped. On the 

other hand, if the flow of the effluent is much greater than the flow of the receiving water, the 

concentration might be close to the CCC much of the time and rarely above the CCC, with 

exceedences being randomly distributed. 

The abilities of ecosystems to recover differ greatly, and depend on the pollutant, the magnitude 

and duration of the exceedence, and the physical and biological features of the ecosystem. 

Documented studies of recoveries are few, but some systems recover from small stresses in six 

weeks whereas other systems take more than ten years to recover from severe stress 3

. Although 

most exceedences are expected to be very small, larger exceedences will occur occasionally. 

Most aquatic ecosystems can probably recover from most exceedences in about three years. 

Therefore, it does not seem reasonable to purposely design for stress above that caused by the 

CCC to occur more than once every three years on the average, just as it does not seem 

reasonable to require that these kinds of stresses only occur once every five or ten years on the 

average. 

If the body of water is not subject to anthropogenic stress other than the exceedences of concern 

and if exceedences as large as a factor of two are rare, it seems reasonable that most bodies of 

water could tolerate exceedences once every three years on the average. In situations in which 

exceedences are grouped, several exceedences might occur in one or two years, but then there 

will be, for example, 10 to 20 years during which no exceedences will occur and the 

concentration will be substantially below the CCC most of the time. In situations in which the 

concentration is often close to the CCC and exceedences are randomly distributed, some adverse 

effect will occur regularly, and small additional, unacceptable effects will occur about every 

6 
third year. The relative long-term ecological consequences of evenly spaced and grouped 

exceedences are unknown, but because most exceedences will probably be small, the long-term 

consequences should be about equal over long periods of time. 

The above considerations lead to a statement of a criterion in the frequency-intensity-duration 

format that is often used to describe rain and snow fall and stream flow, e.g., how often, on the 

average, does more than ten inches of rain fall in a week? The numerical values chosen for 

frequency (or average recurrence interval), intensity (i.e., concentration), and duration (of 

averaging period) are those appropriate for national criteria. Whenever adequately justified, a 

national criterion may be replaced by a site-specific criterion 1

, which may include not only sitespecific criterion concentrations 2

, but also site-specific durations of averaging periods and sitespecific frequencies of allowed exceedences 3

. 

The concentrations, durations, and frequencies specified in criteria are based on biological, 

ecological, and toxicological data, and are designed to protect aquatic organisms and their uses 

from unacceptable effects. Use of criteria for designing waste treatment facilities requires 

selections of an appropriate wasteload allocation model. Dynamic models are preferred for the 

application of water quality criteria, but a steady-state model might have to be used instead of a 

dynamic model in some situations. Regardless of the model that is used, the durations of the 

averaging periods and the frequencies of allowed exceedences must be applied correctly if the 

intended level of protection is to be provided. For example, in the criterion statement frequency 

refers to the average frequency, over a long period of time, of rare events (i.e., exceedences). 

However, in some disciplines, frequency is often thought of in terms of the average frequency, 

over a long period of time, of the years is which rare events occur, without any consideration of 

how many rare events occur within each of those eventful years. The distinction between the 

frequency of events and the frequency of years in important for all those situations in which the 

rare events, e.g., exceedences, tend to occur in groups within the eventful years. The two ways of 

calculating frequency produce the same results in situations in which each rare event occurs in a 

different year because then the frequency of events is the same as the frequency of eventful 

years. 

Because fresh water and salt water have basically different chemical compositions and because 

freshwater and saltwater (i.e., estuarine and true marine) species rarely inhabit the same water 

simultaneously, these National Guidelines provide for the derivation of separate criteria for these 

two kinds of water. For some materials sufficient data might not be available to allow derivation 

of criteria for one or both kinds of water. Even though absolute toxicities might be different in 

fresh and salt waters, such relative data as acute-chronic ratios and bioconcentration factors often 

appear to be similar in the two waters. When data are available to indicate that these ratios and 

factors are probably similar, they are used interchangeably. 

The material for which a criterion is desired is usually defined in terms of a particular chemical 

compound or ion, or a group of closely related compounds or ions, but it might possibly be 

defined in terms of an effluent. These National Guidelines might also be useful for deriving 

criteria for temperature, dissolved oxygen, suspended solids, pH, etc., if the kinds of data on 

which the Guidelines are based are available. 

Because they are meant to be applied only after a decision has been made that a national water 

quality criterion for aquatic organisms is needed for a material, these National Guidelines do not 

7 
address the rationale for making that decision. If the potential for adverse effects on aquatic 

organisms and their uses is part of the basis for deciding whether an aquatic life criterion is 

needed for a material, these Guidelines will probably be helpful in the collection and 

interpretation of relevant data. Such properties as volatility might affect the fate of a material in 

the aquatic environment and might be important when determining whether a criterion is needed 

for a material; for example, aquatic life criteria might not be needed for materials that are highly 

volatile or highly degradable in water. Although such properties can affect how much of the 

material will get from the point of discharge through any allowed mixing zone to some portion of 

the ambient water and can also affect the size of the zone of influence in the ambient water, such 

properties do not affect how much of the material aquatic organisms can tolerate in the zone of 

influence. 

This version of the National Guidelines provides clarifications, additional details, and technical 

and editorial changes from the previous version 9

. These modifications are the result of 

comments on the previous version and subsequent drafts 10, experience gained during the U.S. 

EPA’s use of previous versions and drafts, and advances in aquatic toxicology and related fields. 

Future versions will incorporate new concepts and data as their usefulness is demonstrated. The 

major technical changes incorporated into this version of the National Guidelines are: 

1. The requirement for acute data for freshwater animals has been changed to include more 

tests with invertebrate species. The taxonomic, functional, and probably the toxicological, 

diversities among invertebrate species are greater than those among vertebrate species 

and this should be reflected in the required data. 

2. When available, 96-hr EC50s based on the percentage of fish immobilized plus the 

percentage of fish killed are used instead of 96-hr LC50s for fish; comparable EC50s are 

used instead of LC50s for other species. Such appropriately defined EC50s better reflect 

the total severe acute adverse impact of the test material on the test species than do 

LC50s or narrowly defined EC50s. Acute EC50s that are based on effects that are not 

severe, such as reduction in shell deposition and reduction in growth, are not used in 

calculating the Final Acute Value. 

3. The Final Acute Value is now defined in terms of Genus Mean Acute Values rather than 

Species Mean Acute Values. A Genus Mean Acute Value is the geometric mean of all the 

Species Mean Acute Values available for species in the genus. On the average, species 

within a genus are toxicologically much more similar than species in different genera, 

and so the use of Genus Mean Acute Values will prevent data sets from being biased by 

an overabundance of species in one or a few genera. 

4. The Final Acute Value is now calculated using a method 11 that is not subject to the bias 

and anomalous behavior that the previous method was. The new method is also less 

influenced by one very low value because it always gives equal weight to the four values 

that provide the most information about the cumulative probability of 0.05. Although the 

four values receive the most weight, the other values do have a substantial effect on the 

Final Acute Value (see examples in Appendix 2). 

5. The requirements for using the results of tests with aquatic plants have been made more 

stringent. 

8 
6. Instead of being equal to the Final Acute Value, the Criterion Maximum Concentration is 

now equal to one-half the Final Acute Value. The Criterion Maximum Concentration is 

intended to protect 95 percent of a group of diverse genera, unless a commercially or 

recreationally important species is very sensitive. However, a concentration that would 

severely harm 50 percent of the fifth percentile or 50 percent of a sensitive important 

species cannot be considered to be protective of that percentile or that species. Dividing 

the Final Acute Value by 2 is intended to result in a concentration that will not severely 

adversely affect too many of the organisms. 

7. The lower of the two numbers in the criterion is now called the Criterion Continuous 

Concentration, rather than the Criterion Average Concentration, to more accurately 

reflect the nature of the toxicological data on which it is based. 

8. The statement of a criterion has been changed (a) to include durations of averaging 

periods and frequencies of allowed exceedences that are based on what aquatic organisms 

and their uses can tolerate, and (b) to identify a specific situation in which site-specific 

criteria 1, 2, 3

 are probably desirable. 

In addition, Appendix 1 was added to aid in determining whether a species should be considered 

resident in North America and its taxonomic classification. Appendix 2 explains the calculation 

of the Final Acute Value. 

The amount of guidance in these National Guidelines has been increased, but much of the 

guidance is necessarily qualitative rather than quantitative; much judgment will usually be 

required to derive a water quality criterion for aquatic organisms and their uses. In addition, 

although this version of the National Guidelines attempts to cover all major questions that have 

arisen during use of previous versions and drafts, it undoubtedly does not cover all situations that 

might occur in the future. All necessary decisions should be based on a thorough knowledge of 

aquatic toxicology and an understanding of these Guidelines and should be consistent with the 

spirit of these Guidelines, i.e., to make best use of the available data to derive the most 

appropriate criteria. These National Guidelines should be modified whenever sound scientific 

evidence indicates that a national criterion produced using these Guidelines would probably be 

substantially overprotective or underprotective of the aquatic organisms and their uses on a 

national basis. Derivation of numerical national water quality criteria for aquatic organisms and 

their uses is a complex process and requires knowledge in many areas of aquatic toxicology; any 

deviation from these Guidelines should be carefully considered to ensure that it is consistent with 

other parts of these Guidelines. 

I. Definition of Material of Concern 

A. Each separate chemical that does not ionize substantially in most natural bodies of 

water should usually be considered a separate material, except possibly for 

structurally similar organic compounds that only exist in large quantities as 

commercial mixtures of various compounds and apparently have similar biological, 

chemical, physical, and toxicological properties. 

B. For chemicals that do ionize substantially in most natural bodies of water (e.g., some 

phenols and organic acids, some salts of phenols and organic acids, and most 

9 
inorganic salts and coordination complexes of metals), all forms that would be in 

chemical equilibrium should usually be considered one material. Each different 

oxidation state of a metal and each different nonionizable covalently bonded 

organometallic compound should usually be considered a separate material. 

C. The definition of the material should include an operational analytical component. 

Identification of a material simply, for example, as "sodium" obviously implies "total 

sodium", but leaves room for doubt. If "total" is meant, it should be explicitly stated. 

Even "total" has different operational definitions, some of which do not necessarily 

measure "all that is there" in all samples. Thus, it is also necessary to reference or 

describe the analytical method that is intended. The operational analytical component 

should take into account the analytical and environmental chemistry of the material, 

the desirability of using the same analytical method on samples from laboratory tests, 

ambient water, and aqueous effluents, and various practical considerations, such as 

labor and equipment requirements and whether the method would require 

measurement in the field or would allow measurement after samples are transported 

to a laboratory. 

The primary requirements of the operational analytical component are that it be 

appropriate for use on samples of receiving water, that it be compatible with the 

available toxicity and bioaccumulation data without making extrapolations that are 

too hypothetical, and that it rarely result in underprotection or overprotection of 

aquatic organisms and their uses. Because an ideal analytical measurement will rarely 

be available, a compromise measurement will usually have to be used. This 

compromise measurement must fit with the general approach that if an ambient 

concentration is lower than the national criterion, unacceptable effects will probably 

not occur, i.e., the compromise measurement must not err on the side of 

underprotection when measurements are made on a surface water. Because the 

chemical and physical properties of an effluent are usually quite different from those 

of the receiving water, an analytical method that is acceptable for analyzing an 

effluent might not be appropriate for analyzing a receiving water, and vice versa. If 

the ambient concentration calculated from a measured concentration in an effluent is 

higher than the national criterion, an additional option is to measure the concentration 

after dilution of the effluent with receiving water to determine if the measured 

concentration is lowered by such phenomena as complexation or sorption. A further 

option, of course, is to derive a site-specific criterion 1, 2, 3

. Thus, the criterion should 

be based on an appropriate analytical measurement, but the criterion is not rendered 

useless if an ideal measurement either is not available or is not feasible. 

NOTE: The analytical chemistry of the material might have to be taken into account 

when defining the material or when judging the acceptability of some toxicity tests, 

but a criterion should not be based on the sensitivity of an analytical method. When 

aquatic organisms are more sensitive than routine analytical methods, the proper 

solution is to develop better analytical methods, not to underprotect aquatic life. 

10 
II. Collection of Data 

A. Collect all available data on the material concerning (a) toxicity to, and 

bioaccumulation by, aquatic animals and plants, (b) FDA action levels 12, and (c) 

chronic feeding studies and long-term field studies with wildlife species that regularly 

consume aquatic organisms. 

B. All data that are used should be available in typed, dated, and signed hard copy 

(publication, manuscript, letter, memorandum, etc.) with enough supporting 

information to indicate that acceptable test procedures were used and that the results 

are probably reliable. In some cases it may be appropriate to obtain additional written 

information from the investigator, if possible. Information that is confidential or 

privileged or otherwise not available for distribution should not be used. 

C. Questionable data, whether published or unpublished, should not be used. For 

example, data should usually be rejected if they are from tests that did not contain a 

control treatment, tests in which too many organisms in the control treatment died or 

showed signs of stress or disease, and tests in which distilled or deionized water was 

used as the dilution water without addition of appropriate salts. 

D. Data on technical grade materials may be used if appropriate, but data on formulated 

mixtures and emulsifiable concentrates of the material of concern should not be used. 

E. For some highly volatile, hydrolyzable, or degradable materials it is probably 

appropriate to use only results of flow-through tests in which the concentrations of 

test material in the test solutions were measured often enough using acceptable 

analytical methods. 

F. Data should be rejected if they were obtained using: 

1. Brine shrimp, because they usually only occur naturally in water with salinity 

greater than 35 g/kg. 

2. Species that do not have reproducing wild populations in North America (see 

Appendix 1). 

3. Organisms that were previously exposed to substantial concentrations of the 

test material or other contaminants. 

G. Questionable data, data on formulated mixtures and emulsifiable concentrates, and 

data obtained with non-resident species in North America or previously exposed 

organisms may be used to provide auxiliary information but should not be used in the 

derivation of criteria. 

III. Required data 

A. Certain data should be available to help ensure that each of the four major kinds of 

possible adverse effects receives adequate consideration. Results of acute and chronic 

toxicity tests with representative species of aquatic animals are necessary so that data 

available for tested species can be considered a useful indication of the sensitivities of 

11 
appropriate untested species. Fewer data concerning toxicity to aquatic plants are 

required because procedures for conducting tests with plants and interpreting the 

results of such tests are not as well developed. Data concerning bioaccumulation by 

aquatic organisms are only required if relevant data are available concerning the 

significance of residues in aquatic organisms. 

B. To derive a criterion for freshwater aquatic organisms and their uses, the following 

should be available: 

1. Results of acceptable acute tests (see Section IV) with at least one species 

of freshwater animal in at least eight different families such that all of the 

following are included: 

a. the family Salmonidae in the class Osteichthyes 

b. a second family in the class Osteichthyes, preferably a 

commercially or recreationally important warmwater species 

(e.g., bluegill, channel catfish, etc.) 

c. a third family in the phylum Chordata (may be in the class 

Osteichthyes or may be an amphibian, etc.) 

d. a planktonic crustacean (e.g., cladoceran, copepod, etc.) 

e. a benthic crustacean (e.g., ostracod, isopod, amphipod, crayfish, 

etc.) 

f. an insect (e.g., mayfly, dragonfly, damselfly, stonefly, caddisfly, 

mosquito, midge, etc.) 

g. a family in a phylum other than Arthropoda or Chordata (e.g., 

Rotifera, Annelida, Mollusca, etc.) 

h. a family in any order of insect or any phylum not already 

represented. 

2. Acute-chronic ratios (see Section VI) with species of aquatic animals in at 

least three different families provided that one of the three species: 

• at least one is a fish 

• at least one is an invertebrate 

• at least one is an acutely sensitive freshwater species (the other two 

may be saltwater species). 

3. Results of at least one acceptable test with a freshwater alga or vascular 

plant (see Section VIII). If plants are among the aquatic organisms that 

are most sensitive to the material, results of a test with a plant in another 

phylum (division) should also be available. 

12 
4. At least one acceptable bioconcentration factor determined with an 

appropriate freshwater species, if a maximum permissible tissue 

concentration is available (see Section IX). 

C. To derive a criterion for saltwater aquatic organisms and their uses, the following 

should be available: 

1. Results of acceptable acute tests (see Section IV) with at least one species of 

saltwater animal in at least eight different families such that all of the 

following are included: 

a. two families in the phylum Chordata 

b. a family in a phylum other than Arthropoda or Chordata 

c. either the Mysidae or Penaeidae family 

d. three other families not in the phylum Chordata (may include 

Mysidae or Penaeidae, whichever was not used above) 

e. any other family. 

2. Acute-chronic ratios (see Section VI) with species of aquatic animals in at 

least three different families provided that of the three species: 

• at least one is a fish 

• at least one is an invertebrate 

• at least one is an acutely sensitive saltwater species (the other two may be 

freshwater species). 

3. Results of at least one acceptable test with a saltwater alga or vascular plant 

(see Section VIII). If plants are among the aquatic organisms most sensitive 

to the material, results of a test with a plant in another phylum (division) 

should also be available. 

4. At least one acceptable bioconcentration factor determined with an 

appropriate saltwater species, if a maximum permissible tissue concentration 

is available (see Section IX). 

D. If all the required data are available, a numerical criterion can usually be derived, 

except in special cases. For example, derivation of a criterion might not be possible if 

the available acute-chronic ratios vary by more than a factor of ten with no apparent 

pattern. Also, if a criterion is to be related to a water quality characteristic (see 

Sections V and VII), more data will be necessary. 

Similarly, if all required data are not available, a numerical criterion should not be 

derived except in special cases. For example, even if not enough acute and chronic 

data are available, it might be possible to derive a criterion if the available data 

13 
clearly indicate that the Final Residue Value should be much lower than either the 

Final Chronic Value or Final Plant Value. 

E. Confidence in a criterion usually increases as the amount of available pertinent data 

increases. Thus, additional data are usually desirable. 

IV. Final Acute Value 

A. Appropriate measures of the acute (short-term) toxicity of the material to a variety of 

species of aquatic animals are used to calculate the Final Acute Value. The Final 

Acute Value is an estimate of the concentration of the material corresponding to a 

cumulative probability of 0.05 in the acute toxicity values for the genera with which 

acceptable acute tests have been conducted on the material. However, in some cases, 

if the Species Mean Acute Value of a commercially or recreationally important 

species is lower than the calculated Final Acute Value, then that Species Mean Acute 

Value replaces the calculated Final Acute Value in order to provide protection for that 

important species. 

B. Acute toxicity tests should have been conducted using acceptable procedures 13. 

C. Except for test with saltwater annelids and mysids, results of acute tests during which 

the test organisms were fed should not be used, unless data indicate that the food did 

not affect the toxicity of the test material. 

D. Results of acute tests conducted in unusual dilution water, e.g., dilution water in 

which total organic carbon or particulate matter exceeded 5 mg/L, should not be used, 

unless a relationship is developed between acute toxicity and organic carbon or 

particulate matter or unless data show that organic carbon, particulate matter, etc., do 

not affect toxicity. 

E. Acute values should be based on endpoints which reflect the total severe acute 

adverse impact of the test material on the organisms used in the test. Therefore, only 

the following kinds of data on acute toxicity to aquatic animals should be used: 

1. Tests with daphnids and other cladocerans should be started with organisms less 

than 24 hours old and tests with midges should be started with second- or thirdinstar larvae. The result should be the 48-hr EC50 based on percentage of 

organisms immobilized plus percentage of organisms killed. If such an EC50 is 

not available from a test, the 48-hr LC50 should be used in place of the desired 

48-hr EC50. An EC50 or LC50 of longer than 48 hr can be used as long as the 

animals were not fed and the control animals were acceptable at the end of the 

test. 

2. The result of a test with embryos and larvae of barnacles, bivalve molluscs 

(clams, mussels, oysters, and scallops), sea urchins, lobsters, crabs, shrimp, and 

abalones, should be the 96-hr EC50 based on the percentage of organisms with 

incompletely developed shells plus the percentage of organisms killed. If such an 

EC50 is not available from a test, the lower of the 96-hr EC50 based on the 

percentage of organisms with incompletely developed shells and the 96-hr LC50 

14 
should be used in place of the desired 96-hr EC50. If the duration of the test was 

between 48 and 96 hr, the EC50 or LC50 at the end of the test should be used. 

3. The acute values from tests with all other freshwater and saltwater animal species 

and older life stages of barnacles, bivalve molluscs, sea urchins, lobsters, crabs, 

shrimps, and abalones should be the 96-hr EC50 based on the percentage of 

organisms exhibiting loss of equilibrium plus the percentage of organisms 

immobilized plus the percentage of organisms killed. If such an EC50 is not 

available from a test, the 96-hr LC50 should be used in place of the desired 96-hr 

EC50. 

4. Tests with single-celled organisms are not considered acute tests, even if the 

duration was 96 hours or less. 

5. If the tests were conducted properly, acute values reported as "greater than" 

values and those which are above the solubility of the test material should be 

used, because rejection of such acute values would unnecessarily lower the Final 

Acute Value by eliminating acute values for resistant species. 

F. If the acute toxicity of the material to aquatic animals apparently has been shown to 

be related to a water quality characteristic such as hardness or particulate matter for 

freshwater animals or salinity or particulate matter for saltwater animals, a Final 

Acute Equation should be derived based on that water quality characteristic. Go to 

Section V. 

G. If the available data indicate that one or more life stages are at least a factor of two 

more resistant than one or more other life stages of the same species, the data for the 

more resistant life stages should not be used in the calculation of the Species Mean 

Acute Value because a species can only be considered protected from acute toxicity if 

all life stages are protected. 

H. The agreement of the data within and between species should be considered. Acute 

values that appear to be questionable in comparison with other acute and chronic data 

for the same species and for other species in the same genus probably should not be 

used in calculation of a Species Mean Acute Value. For example, if the acute values 

available for a species or genus differ by more than a factor of 10, some or all of the 

values probably should not be used in calculations. 

I. For each species for which at least one acute value is available, the Species Mean 

Acute Value (SMAV) should be calculated as the geometric mean of the results of all 

flow-through tests in which the concentrations of test material were measured. For a 

species for which no such result is available, the SMAV should be calculated as the 

geometric mean of all available acute values, i.e., results of flow-through tests in 

which the concentrations were not measured and results of static and renewal tests 

based on initial concentrations (nominal concentrations are acceptable for most test 

materials if measured concentrations are not available) of test material. 

NOTE: Data reported by original investigators should not be rounded off. Results of 

all intermediate calculations should be rounded 14 to four significant digits. 

15 
NOTE: The geometric mean of N numbers is the Nth root of the product of the N 

numbers. Alternatively, the geometric mean can be calculated by adding the 

logarithms of the N numbers, dividing the sum by N, and taking the antilog of the 

quotient. The geometric mean of two numbers is the square root of the product of the 

two numbers, and the geometric mean of one number is that number. Either natural 

(base e) or common (base 10) logarithms can be used to calculate geometric means as 

long as they are used consistently within each set of data, i.e., the antilog used must 

match the logarithm used. 

NOTE: Geometric means, rather than arithmetic means, are used here because the 

distributions of sensitivities of individual organisms in toxicity tests on most 

materials and the distributions of sensitivities of species within a genus are more 

likely to be lognormal than normal. Similarly, geometric means are used for acutechronic ratios and bioconcentration factors because quotients are likely to be closer to 

lognormal than normal distributions. In addition, division of the geometric mean of a 

set of numerators by the geometric mean of the set of corresponding denominators 

will result in the geometric mean of the set of corresponding quotients. 

J. For each genus for which one or more SMAVs are available, the Genus Mean Acute 

Value (GMAV) should be calculated as the geometric mean of the SMAVs available 

for the genus. 

K. Order the GMAVs from high to low. 

L. Assign ranks, R, to the GMAVs from "1" for the lowest to "N" for the highest. If two 

or more GMAVs are identical, arbitrarily assign them successive ranks. 

M. Calculate the cumulative probability, P, for each GMAV as R/(N+1). 

N. Select the four GMAVs which have cumulative probabilities closest to 0.05 (if there 

are less than 59 GMAVs, these will always be the four lowest GMAVs). 

O. Using the selected GMAVs and Ps, calculate 

S2 = 

)4/))((()(

4/))ln(())((ln

2

2 2

∑∑

∑ ∑

−

−

F P

GMAV GMAV

L = ∑ − ∑ PSGMAV 4/)))(()(ln(

A = S )05.0( + L

FAV = A

e

(See 11 for development of the calculation procedure and Appendix 2 for an example 

calculations and computer program.) 

NOTE: Natural logarithms (logarithms to base e, denoted as ln) are used herein 

merely because they are easier to use on some hand calculators and computers than 

common (base 10) logarithms. Consistent use of either will produce the same result. 

16 
P. If for a commercially or recreationally important species the geometric mean of the 

acute values from the flow-through tests in which the concentrations of test material 

were measured is lower than the calculated Final Acute Value, then that geometric 

mean should be used as the Final Acute Value instead of the calculated Final Acute 

Value. 

Q. Go to Section VI. 

V. Final Acute Equation 

A. When enough data are available to show that acute toxicity to two or more species is 

similarly related to a water quality characteristic, the relationship should be taken into 

account as described in Sections B-G below or using analysis of covariance 15, 16. 

The two methods are equivalent and produce identical results. The manual meth

described below provides an understanding of this application of covariance analysis, 

but computerized versions of covariance analysis are much more convenient for 

analyzing large data sets. If two or more factors affect toxicity, multiple regression 

analysis should be used. 

od 

B. For each species for which comparable acute toxicity values are available at two or 

more different values of the water quality characteristic, perform a least squares 

regression of the acute toxicity values on the corresponding values of the water 

quality characteristic to obtain the slope and its 95% confidence limits for each 

species. 

NOTE: Because the best documented relationship is that between hardness and acute 

toxicity of metals in fresh water and a log-log relationship fits these data, geometric 

means and natural logarithms of both toxicity and water quality are used in the rest of 

this section. For relationships based on other water quality characteristics, such as 

pH, temperature, or salinity, no transformation or a different transformation might fit 

the data better, and appropriate changes will be necessary throughout this section. 

C. Decide whether the data for each species is useful, taking into account the range and 

number of the tested values of the water quality characteristic and the degree of 

agreement within and between species. For example, a slope based on six data points 

might be of limited value if it is based only on data for a very narrow range of values 

of the water quality characteristic. A slope based on only two data points, however, 

might be useful if it is consistent with other information and if the two points cover a 

broad enough range of the water quality characteristic. In addition, acute values that 

appear to be questionable in comparison with other acute and chronic data available 

for the same species and for other species in the same genus probably should not be 

used. For example, if after adjustment for the water quality characteristic, the acute 

values available for a species or genus differ by more than a factor of 10, rejection of 

some or all of the values is probably appropriate. If useful slopes are not available for 

at least one fish and one invertebrate or if the available slopes are too dissimilar or if 

too few data are available to adequately define the relationship between acute toxicity 

and the water quality characteristic, return to Section IV.G., using the results of tests 

17 
conducted under conditions and in waters similar to those commonly used for toxicity 

tests with the species. 

D. Individually for each species calculate the geometric mean of the available acute 

values and then divide each of the acute values for a species by the mean for the 

species. This normalizes the acute values so that the geometric mean of the 

normalized values for each species individually and for any combination of species is 

1.0. 

E. Similarly normalize the values of the water quality characteristic for each species 

individually. 

F. Individually for each species perform a least squares regression of the normalized 

acute toxicity values on the corresponding normalized values of the water quality 

characteristic. The resulting slopes and 95% confidence limits will be identical to 

those obtained in Section B above. Now, however, if the data are actually plotted, the 

line of best fit for each individual species will go through the point 1,1 in the center of 

the graph. 

G. Treat all the normalized data as if they were all for the same species and perform a 

least squares regression of all the normalized acute values on the corresponding 

normalized values of the water quality characteristic to obtain the pooled acute slope, 

V, and its 95% confidence limits. If all the normalized data are actually plotted, the 

line of best fit will go through the point 1,1 in the center of the graph. 

H. For each species calculate the geometric mean, W, of the acute toxicity values and the 

geometric mean, X, of the values of the water quality characteristic. (These were 

calculated in steps D and E above.) 

I. For each species calculate the logarithm, Y, of the SMAV at a selected value, Z, of 

the water quality characteristic using the equation: 

Y = ln W – V(ln X – ln Z). 

J. For each species calculate the SMAV at Z using the equation: SMAV = eY. 

NOTE: Alternatively, the SMAVs at Z can be obtained by skipping step H above, 

using the equations in steps I and J to adjust each acute value individually to Z, and 

then calculating the geometric mean of the adjusted values for each species 

individually. This alternative procedure allows an examination of the range of the 

adjusted acute values for each species. 

K. Obtain the Final Acute Value at Z by using the procedure described in Section IV.JO. 

L. If the SMAV at Z of a commercially or recreationally important species is lower than 

the calculated Final Acute Value at Z, then that SMAV should be used as the Final 

Acute Value at Z instead of the calculated Final Acute Value. 

M. The Final Acute Equation is written as: Final Acute Value = e(V[ln(water quality characteristic)] 

+ ln A – V[ln Z]), where V = pooled acute slope and A = Final Acute Value at Z. Because 

18 
V, A, and Z are known, the Final Acute Value can be calculated for any selected 

value of the water quality characteristic. 

VI. Final Chronic Value 

A. Depending on the data that are available concerning chronic toxicity to aquatic 

animals, the Final Chronic Value might be calculated in the same manner as the Final 

Acute Value or by dividing the Final Acute Value by the Final Acute-Chronic Ratio. 

In some cases it may not be possible to calculate a Final Chronic Value. 

NOTE: As the name implies, the acute-chronic ration (ARC) is a way of relating 

acute and chronic toxicities. The acute-chronic ratio is basically the inverse of the 

application factor, but this new name is better because it is more descriptive and 

should help prevent confusion between "application factors" and "safety factors". 

Acute-chronic ratios and application factors are ways of relating the acute and chronic 

toxicities of a material to aquatic organisms. Safety factors are used to provide an 

extra margin of safety beyond the known or estimated sensitivities of aquatic 

organisms. Another advantage of the acute-chronic ratio is that it will usually be 

greater than one; this should avoid the confusion as to whether a large application 

factor is one that is close to unity or one that has a denominator that is much greater 

than the numerator. 

B. Chronic values should be based on results of flow-through (except renewal is 

acceptable for daphnids) chronic tests in which the concentrations of test material in 

the test solutions were properly measured at appropriate times during the test. 

C. Results of chronic tests in which survival, growth, or reproduction in the control 

treatment was unacceptably low should not be used. The limits of acceptability will 

depend on the species. 

D. Results of chronic tests conducted in unusual dilution water, e.g., dilution water in 

which total organic carbon or particulate matter exceeded 5 mg/L, should not be used, 

unless a relationship is developed between chronic toxicity and organic carbon or 

particulate matter or unless data show that organic carbon, particulate matter, etc., do 

not affect toxicity. 

E. Chronic values should be based on endpoints and lengths of exposure appropriate to 

the species. Therefore, only results of the following kinds of chronic toxicity tests 

should be used: 

1. Life-cycle toxicity tests consisting of exposures of each of two or more groups of 

individuals of a species to a different concentration of the test material throughout 

a life cycle. To ensure that all life stages and life processes are exposed, tests 

with fish should begin with embryos or newly hatched young less than 48 hours 

old, continue through maturation and reproduction, and should end not less than 

24 days (90 days for salmonids) after the hatching of the next generation. Tests 

with daphnids should begin with young less than 24 hours old and last for not less 

than 21 days. Tests with mysids should begin with young less than 24 hours old 

and continue until 7 days past the median time of first brood release in the 

19 
controls. For fish, data should be obtained and analyzed on survival and growth 

of adults and young, maturation of males and females, eggs spawned per female, 

embryo viability (salmonids only), and hatchability. For daphnids, data should be 

obtained and analyzed on survival and young per female. For mysids, data should 

be obtained and analyzed on survival, growth, and young per female. 

2. Partial life-cycle toxicity tests consisting of exposures of each of two or more 

groups of individuals of a species of fish to a different concentration of the test 

material through most portions of a life cycle. Partial life-cycle tests are allowed 

with fish species that require more than a year to reach sexual maturity, so that all 

major life stages can be exposed to the test material in less than 15 months. 

Exposure to the test material should begin with immature juveniles at least 2 

months prior to active gonad development, continue through maturation and 

reproduction, and end not less than 24 days (90 days for salmonids) after the 

hatching of the next generation. Data should be obtained and analyzed on 

survival and growth of adults and young, maturation of males and females, eggs 

spawned per female, embryo viability (salmonids only), and hatchability. 

3. Early life-stage toxicity tests consisting of 28- to 32-day (60 days post hatch for 

salmonids) exposures of the early life stages of a species of fish from shortly after 

fertilization through embryonic, larval, and early juvenile development. Data 

should be obtained and analyzed on survival and growth. 

NOTE: Results of an early life-stage test are used as predictions of results of 

life-cycle and partial life-cycle tests with the same species. Therefore, when 

results of a life-cycle or partial life-cycle test are available, results of an early lifestage test with the same species should not be used. Also, results of early lifestage tests in which the incidence of mortalities or abnormalities increased 

substantially near the end of the test should not be used because results of such 

tests are possibly not good predictions of the results of comparable life-cycle or 

partial life-cycle tests. 

F. A chronic value may be obtained by calculating the geometric mean of the lower and 

upper chronic limits from a chronic test or by analyzing chronic data using regression 

analysis. A lower chronic limit is the highest tested concentration (a) in an acceptable 

chronic test, (b) which did not cause an unacceptable amount of adverse effect on any 

of the specified biological measurements, and (c) below which no tested 

concentration caused an unacceptable effect. An upper chronic limit is the lowest 

tested concentration (a) in an acceptable chronic test, (b) which did cause an 

unacceptable amount of adverse effect on one or more of the specified biological 

measurements, and (c) above which all tested concentrations also caused such an 

effect. 

NOTE: Because various authors have used a variety of terms and definitions to 

interpret and report results of chronic tests, reported results should be reviewed 

carefully. The amount of effect that is considered unacceptable is often based on a 

statistical hypothesis test, but might also be defined in terms of a specified percent 

reduction from the controls. A small percent reduction (e.g., 3%) might be 

20 
considered acceptable even if it is statistically significantly different from the control, 

whereas a large percent reduction (e.g., 30%) might be considered unacceptable even 

if it is not statistically significant. 

G. If the chronic toxicity of the material to aquatic animals apparently has been shown to 

be related to a water quality characteristic such as hardness or particulate matter for 

freshwater animals or salinity or particulate matter for saltwater animals, a Final 

Chronic Equation should be derived based on that water quality characteristic. Go to 

Section VII. 

H. If chronic values are available for species in eight families as described in Sections 

III.B.1 or III.C.1, a Species Mean Chronic Value (SMCV) should be calculated for 

each species for which at least one chronic value is available by calculating the 

geometric mean of all chronic values available for the species, and appropriate Genus 

Mean Chronic Values should be calculated. The Final Chronic Value should then be 

obtained using the procedure described in Section IV.J-O. Then go to Section VI.M. 

I. For each chronic value for which at least one corresponding appropriate acute value is 

available, calculate an acute-chronic ratio, using for the numerator the geometric 

mean of the results of all acceptable flow-through (except static is acceptable for 

daphnids) acute tests in the same dilution water and in which the concentrations were 

measured. For fish, the acute test(s) should have been conducted with juveniles. The 

acute test(s) should have been part of the same study as the chronic test. If acute tests 

were not conducted as part of the same study, acute tests conducted in the same 

laboratory and dilution water, but in a different study, may be used. If no such acute 

tests are available, results of acute tests conducted in the same dilution water in a 

different laboratory may be used. If no such acute tests are available, an acutechronic ratio should not be calculated. 

J. For each species, calculate the species mean acute-chronic ratio as the geometric 

mean of all acute-chronic ratios available for that species. 

K. For some materials the acute-chronic ratio seems to be the same for all species, but 

for other materials the ratio seems to increase or decrease as the Species Mean Acute 

Value (SMAV) increases. Thus the Final Acute-Chronic Ratio can be obtained in 

four ways, depending on the data available: 

1. If the species mean acute-chronic ratios seems to increase or decrease as the 

SMAV increases, the Final Acute-Chronic Ratio should be calculated as the 

geometric mean of the acute-chronic ratios for species whose SMAVs are 

close to the Final Acute Value. 

2. If no major trend is apparent and the acute-chronic ratios for a number of 

species are within a factor of ten, the Final Acute-Chronic Ratio should be 

calculated as the geometric mean of all the species mean acute-chronic ratios 

available for both freshwater and saltwater species. 

3. For acute tests conducted on metals and possibly other substances with 

embryos and larvae of barnacles, bivalve molluscs, sea urchins, lobsters, 

21 
crabs, shrimp, and abalones (see Section IV.E.2), it is probably appropriate to 

assume that the acute-chronic ratio is 2. Chronic tests are very difficult to 

conduct with most such species, but it is likely that the sensitivities of 

embryos and larvae would determine the results of life-cycle tests. Thus, if 

the lowest available SMAVs were determined with embryos and larvae of 

such species, the Final Acute-Chronic Ratio should probably be assumed to be 

2, so that the Final Chronic Value is equal to the Criterion Maximum 

Concentration (see Section XI.B). 

4. If the most appropriate species mean acute-chronic ratios are less than 2.0, and 

especially if they are less than 1.0, acclimation has probably occurred during 

the chronic test. Because continuous exposure and acclimation cannot be 

assured to provide adequate protection in field situations, the Final AcuteChronic Ratio should be assumed to be 2, so that the Final Chronic Value is 

equal to the Criterion Maximum Concentration (see Section XI.B). 

If the available species mean acute-chronic ratios do not fit one of these cases, a Final 

Acute-Chronic Ratio probably cannot be obtained, and a Final Chronic Value 

probably cannot be calculated. 

L. Calculate the Final Chronic Value by dividing the Final Acute Value by the Final 

Acute-Chronic Ratio. If there was a Final Acute Equation rather than a Final Acute 

Value, see also Section VII.A. 

M. If the Species Mean Chronic Value of a commercially or recreationally important 

species is lower than the calculated Final Chronic Value, then that Species Mean 

Chronic Value should be used as the Final Chronic Value instead of the calculated 

Final Chronic Value. 

N. Go to Section VIII. 

VII. Final Chronic Equation 

A. A Final Chronic Equation can be derived in two ways. The procedure described here 

in Section A will result in the chronic slope being the same as the acute slope. The 

procedure described in Sections B-N will usually result in the chronic slope being 

different from the actual slope. 

1. If acute-chronic ratios are available for enough species at enough values of 

the water quality characteristic to indicate that the acute-chronic ratio is 

probably the same for all species and is probably independent of the water 

quality characteristic, calculate the Final Acute-Chronic Ratio as the 

geometric mean of the available species mean acute-chronic ratios. 

2. Calculate the Final Chronic Value at the selected value Z of the water 

quality characteristic by dividing the Final Acute Value at Z (see Section 

V.M.) by the Final Acute-Chronic Ratio. 

22 
3. Use V = pooled acute slope (see section V.M.) as L = pooled chronic 

slope. 

4. Go to Section VII.M. 

B. When enough data are available to show that chronic toxicity to at least one species is 

related to a water quality characteristic, the relationship should be taken into account 

as described in Sections B-G below or using analysis of covariance 15, 16. The two 

methods are equivalent and produce identical results. The manual method described 

below provides an understanding of this application of covariance analysis, but 

computerized versions of covariance analysis are much more convenient for 

analyzing large data sets. If two more factors affect toxicity, multiple regression 

analysis should be used. 

C. For each species for which comparable chronic toxicity values are available at two or 

more different values of the water quality characteristic, perform a least squares 

regression of the chronic toxicity values on the corresponding values of the water 

quality characteristic to obtain the slope and its 95% confidence limits for each 

species. 

NOTE: Because the best documented relationship is that between hardness and acute 

toxicity of metals in fresh water and a log-log relationship fits these data, geometric 

means and natural logarithms of both toxicity and water quality are used in the rest of 

this section. For relationships based on other water quality characteristics, such as 

pH, temperature, or salinity, no transformation or a different transformation might fit 

the data better, and appropriate changes will be necessary throughout this section. It 

is probably preferable, but not necessary, to use the same transformation that was 

used with the acute values in Section V. 

D. Decide whether the data for each species is useful, taking into account the range and 

number of the tested values of the water quality characteristic and the degree of 

agreement within and between species. For example, a slope based on six data points 

might be of limited value if it is based only on data for a very narrow range of values 

of the water quality characteristic. A slope based on only two data points, however, 

might be useful if it is consistent with other information and if the two points cover a 

broad enough range of the water quality characteristic. In addition, chronic values 

that appear to be questionable in comparison with other acute and chronic data 

available for the same species and for other species in the same genus probably 

should not be used. For example, if after adjustment for the water quality 

characteristic, the chronic values available for a species or genus differ by more than 

a factor of 10, rejection of some or all of the values is probably appropriate. If a 

useful chronic slope is not available for at least one species or if the available slopes 

are too dissimilar or if too few data are available to adequately define the relationship 

between chronic toxicity and the water quality characteristic, it might be appropriate 

to assume that the chronic slope is the same as the acute slope, which is equivalent to 

assuming that the acute-chronic ratio is independent of the water quality 

characteristic. Alternatively, return to Section VI.H, using the results of tests 

23 
conducted under conditions and in waters similar to those commonly used for toxicity 

tests with the species. 

E. Individually for each species calculate the geometric mean of the available chronic 

values and then divide each chronic value for a species by the mean for the species. 

This normalizes the chronic values so that the geometric mean of the normalized 

values for each species individually and for any combination of species is 1.0. 

F. Similarly normalize the values of the water quality characteristic for each species 

individually. 

G. Individually for each species perform a least squares regression of the normalized 

chronic toxicity values on the corresponding normalized values of the water quality 

characteristic. The resulting slopes and the 95% confidence limits will be identical to 

those obtained in Section B above. Now, however, if the data are actually plotted, the 

line of best fit for each individual species will go through the point 1,1 in the center of 

the graph. 

H. Treat all the normalized data as if they were all for the same species and perform a 

least squares regression of all the normalized chronic values on the corresponding 

normalized values of the water quality characteristic to obtain the pooled chronic 

slope, L, and its 95% confidence limits. If all the normalized data are actually 

plotted, the line of best fit will go through the point 1,1 in the center of the graph. 

I. For each species calculate the geometric mean, M, of the toxicity values and the 

geometric mean, P, of the values of the water quality characteristic. (These were 

calculated in steps E and F above.) 

J. For each species calculated the logarithm, Q, of the Species Mean Chronic Value at a 

selected value, Z, of the water quality characteristic using the equation: Q = ln M – 

L(ln P – ln Z). 

NOTE: Although it is not necessary, it will usually be best to use the same value of 

the water quality characteristic here as was used in Section V.I. 

K. For each species calculate a Species Mean Chronic Value at Z using the equation: 

SMCV = eQ. 

NOTE: Alternatively, the Species Mean Chronic Values at Z can be obtained by 

skipping step J above, using the equations in steps J and K to adjust each acute value 

individually to Z and then calculating the geometric means of the adjusted values for 

each species individually. This alternative procedure allows an examination of the 

range of the adjusted chronic values for each species. 

L. Obtain the Final Chronic Value at Z by using the procedure described in Section IV.JO. 

M. If the Species Mean Chronic Value at Z of a commercially or recreationally important 

species is lower than the calculated Final Chronic Value at Z, then that Species Mean 

24 
N. The Final Chronic Equation is written as: Final Chronic Value = e(L[ln(water quality 

characteristic)] + ln S – L [ln Z]), where L = pooled chronic slope and S = Final Chronic Value 

at Z. Because L, S and Z are known, the Final Chronic Value can be calculated for 

any selected value of the water quality characteristic. 

VIII. Final Plant Value 

A. Appropriate measures of the toxicity of the material to aquatic plants are used to 

compare the relative sensitivities of aquatic plants and animals. Although procedures 

for conducting and interpreting the results of toxicity tests with plants are not well 

developed, results of tests with plants usually indicate that criteria which adequately 

protect aquatic animals and their uses will probably also protect aquatic plants and 

their uses. 

B. A plant value is the result of a 96-hr test conducted with an alga or a chronic test 

conducted with an aquatic vascular plant. 

NOTE: A test of the toxicity of a metal to a plant usually should not be used if the 

medium contained an excessive amount of a complexing agent, such as EDTA, that 

might affect the toxicity of the metal. Concentrations of EDTA above about 200 μg/L 

should probably be considered excessive. 

C. The Final Plant Value should be obtained by selecting the lowest result from a test 

with an important aquatic plant species in which the concentrations of test material 

were measured and the endpoint was biologically important. 

IX. Final Residue Value 

A. The Final Residue Value is intended to (a) prevent concentrations in commercially or 

recreationally important aquatic species from affecting marketability because of 

exceedance of applicable FDA action levels and (b) protect wildlife, including fishes 

and birds, that consume aquatic organisms from demonstrated unacceptable effects. 

The Final Residue Value is the lowest of the residue values that are obtained by 

dividing maximum permissible tissue concentrations by appropriate bioconcentration 

or bioaccumulation factors. A maximum permissible tissue concentration is either (a) 

an FDA action level 12 for fish oil or for the edible portion of fish or shellfish, or (b) a 

maximum acceptable dietary intake based on observations on survival, growth, or 

reproduction in a chronic wildlife feeding study or a long-term wildlife field study. If 

no maximum permissible tissue concentration is available, go to Section X because 

no Final Residue Value can be derived. 

B. Bioconcentration factors (BCFs) and bioaccumulation factors (BAFs) are quotients of 

the concentration of a material in one or more tissues of an aquatic organism divided 

by the average concentration in the solution in which the organism had been living. 

A BCF is intended to account only for net uptake directly from water, and thus almost 

25 
has to be measured in a laboratory test. Some uptake during the bioconcentration test 

might not be directly from water if the food sorbs some of the test material before it is 

eaten by the test organisms. A BAF is intended to account for the net uptake from 

both food and water in a real-world situation. A BAF almost has to be measured in a 

field situation in which predators accumulate the material directly from water and by 

consuming prey that itself could have accumulated the material from both food and 

water. The BCF and BAF are probably similar for a material with a low BCF, but the 

BAF is probably higher than the BCF for materials with high BCFs. Although BCFs 

are not too difficult to determine, very few BAFs have been measured acceptably 

because it is necessary to make enough measurements of the concentration of the 

material in water to show that it was reasonably constant for a long enough period of 

time over the range of territory inhabited by the organisms. Because so few 

acceptable BAFs are available, only BCFs will be discussed further. However, if an 

acceptable BAF is available for a material, it should be used instead of any available 

BCFs. 

C. If a maximum permissible tissue concentration is available for a substance (e.g., 

parent material, parent material plus metabolites, etc.), the tissue concentration used 

in the calculation of the BCF should be for the same substance. Otherwise, the tissue 

concentration used in the calculation of the BCF should be that of the material and its 

metabolites which are structurally similar and are not much more soluble in water 

than the parent material. 

D.

1. A BCF should be used only if the test was flow-through, the BCF was 

calculated based on measured concentrations of the test material in tissue and 

in the test solution, and the exposure continued at least until either apparent 

steady-state or 28 days was reached. Steady-state is reached when the BCF 

does not change significantly over a period of time, such as two days or 16 

percent of the length of the exposure, whichever is longer. The BCF used 

from a test should be the highest of (a) the apparent steady-state BCF, if 

apparent steady-state was reached, (b) the highest BCF obtained, if apparent 

steady-state was not reached, and (c) the projected steady-state BCF, if 

calculated. 

2. Whenever a BCF is determined for a lipophilic material, the percent lipids 

should also be determined in the tissue(s) for which the BCF was calculated. 

3. A BCF obtained from an exposure that adversely affected the test organisms 

may be used only if it is similar to a BCF obtained with unaffected organisms 

of the same species at lower concentrations that did not cause adverse effects. 

4. Because maximum permissible tissue concentrations are almost never based 

on dry weights, a BCF calculated using dry tissue weights must be converted 

to a wet tissue weight basis. If no conversion factor is reported with the BCF, 

multiply the dry weight BCF by 0.1 for plankton and by 0.2 for individual 

species of fishes and invertebrates 17. 

26 
5. If more than one acceptable BCF is available for a species, the geometric 

mean of the available values should be used, except that if the BCFs are from 

different lengths of exposure and the BCF increases with length of exposure, 

the BCF for the longest exposure should be used. 

E. If enough pertinent data exist, several residue values can be calculated by dividing 

maximum permissible tissue concentrations by appropriate BCFs: 

1. For each available maximum acceptable dietary intake derived from a chronic 

feeding study or a long-term field study with wildlife, including birds and 

aquatic organisms, the appropriate BCF is based on the whole body of aquatic 

species which constitute or represent a major portion of the diet of the tested 

wildlife species. 

2. For an FDA action level for fish or shellfish, the appropriate BCF is the 

highest geometric mean species BCF for the edible portion (muscle for 

decapods, muscle with or without skin for fishes, adductor muscle for 

scallops, and total soft tissue for other bivalve molluscs) of a consumed 

species. The highest species BCF is used because FDA action levels are 

applied on a species-by-species basis. 

F. For lipophilic materials, it might be possible to calculate additional residue values. 

Because the steady-state BCF for a lipophilic material seems to be proportional to 

percent lipids from one tissue to another and from one species to another 18, 19, 20, 

extrapolations can be made from tested tissues or species to untested tissues or 

species on the basis of percent lipids. 

1. For each BCF for which the percent lipids is known for the same tissue for 

which the BCF was measured, normalize the BCF to a one percent lipid basis 

by dividing the BCF by the percent lipids. This adjustment to a one percent 

lipid basis is intended to make all the measured BCFs for a material 

comparable regardless of the species or tissue with which the BCF was 

measured. 

2. Calculate the geometric mean normalized BCF. Data for both saltwater and 

freshwater species should be used to determine the mean normalized BCF, 

unless the data show that the normalized BCFs are probably not similar. 

3. Calculate all possible residue values by dividing the available maximum 

permissible tissue concentrations by the mean normalized BCF and by the 

percent lipids values appropriate to the maximum permissible tissue 

concentrations, i.e.,

Residue Value = 

normalized mean( percent te(appropria BCF) )lipids

concentrat tissueepermissibl maximum( )ion

a. For an FDA action level for fish oil, the appropriate percent lipids 

value is 100. 

27 
b. For an FDA action level for fish, the appropriate percent lipids value 

is 11 for freshwater criteria and 10 for saltwater criteria because 

FDA action levels are applied on a species-by-species basis to 

commonly consumed species. The highest lipid contents in the 

edible portions of important consumed species are about 11 percent 

for both the freshwater chinook salmon and lake trout and about 10 

percent for the saltwater Atlantic herring 21. 

c. For a maximum acceptable dietary intake derived from a chronic 

feeding study or a long-term field study with wildlife, the 

appropriate percent lipids is that of an aquatic species or group of 

aquatic species which constitute a major portion of the diet of the 

wildlife species. 

G. The Final Residue Value is obtained by selecting the lowest of the available residue 

values. 

NOTE: In some cases the Final Residue Value will not be low enough. For 

example, a residue value calculated from an FDA action level will probably result in 

an average concentration in the edible portion of a fatty species that is at the action 

level. Some individual organisms, and possibly some species, will have residue 

concentrations higher than the mean value but no mechanism has been devised to 

provide appropriate additional protection. Also, some chronic feeding studies and 

long-term field studies with wildlife identify concentrations that cause adverse effects 

but do not identify concentrations which do not cause adverse effects; again no 

mechanism has been devised to provide appropriate additional protection. These are 

some of the species and uses that are not protected at all times in all places. 

X. Other Data 

Pertinent information that could not be used in earlier sections might be available 

concerning adverse effects on aquatic organisms and their uses. The most important 

of these are data on cumulative and delayed toxicity, flavor impairment, reduction in 

survival, growth, or reproduction, or any other adverse effect that has been shown to 

be biologically important. Especially important are data for species for which no 

other data are available. Data from behavioral, biochemical, physiological, 

microcosm, and field studies might also be available. Data might be available from 

tests conducted in unusual dilution water (see IV.D and VI.D), from chronic tests in 

which the concentrations were not measured (see VI.B), from tests with previously 

exposed organisms (see II.F), and from tests on formulated mixtures or emulsifiable 

concentrates (see II.D). Such data might affect a criterion if the data were obtained 

with an important species, the test concentrations were measured, and the endpoint 

was biologically important. 

XI. Criterion 

A. A criterion consists of two concentrations: the Criterion Maximum Concentration 

and the Criterion Continuous Concentration. 

28 
B. The Criterion Maximum Concentration (CMC) is equal to one-half the Final Acute 

Value. 

C. The Criterion Continuous Concentration (CCC) is equal to the lowest of the Final 

Chronic Value, the Final Plant Value, and the Final Residue Value, unless other data 

(see Section X) show that a lower value should be used. If toxicity is related to a 

water quality characteristic, the CCC is obtained from the Final Chronic Equation, the 

Final Plant Value, and the Final Residue Value by selecting the one, or the 

combination, that results in the lowest concentrations in the usual range of the water 

quality characteristic, unless other data (see Section X) show that a lower value 

should be used. 

D. Round 14 both the CMC and the CCC to two significant digits. 

E. The criterion is stated as: 

The procedures described in the "Guidelines for Deriving Numerical National Water 

Quality Criteria for the Protection of Aquatic Organisms and Their Uses" indicate 

that, except possibly where a locally important species is very sensitive, (1) aquatic 

organisms and their uses should not be affected unacceptably if the four-day average 

concentration of (2) does not exceed (3) μg/L more than once every three years on the 

average and if the one-hour average concentration does not exceed (4) μg/L more 

than once every three years on the average. 

where (1) = insert "freshwater" or "saltwater" 

(2) = insert name of material 

(3) = insert the Criterion Continuous Concentration 

(4) = insert the Criterion Maximum Concentration. 

XII. Final Review 

A. The derivation of the criterion should be carefully reviewed by rechecking each step 

of the Guidelines. Items that should be especially checked are: 

1. If unpublished data are used, are they well documented? 

2. Are all required data available? 

3. Is the range of acute values for any species greater than a factor of 10? 

4. Is the range of Species Mean Acute Values for any genus greater than a 

factor of 10? 

5. Is there more than a factor of ten difference between the four lowest 

Genus Mean Acute Values? 

6. Are any of the four lowest Genus Mean Acute Values questionable? 

29 
7. Is the Final Acute Value reasonable in comparison with the Species Mean 

Acute Values and Genus Mean Acute Values? 

8. For any commercially or recreationally important species, is the geometric 

mean of the acute values from flow-through tests in which the 

concentrations of test material were measured lower than the Final Acute 

Value? 

9. Are any of the chronic values questionable? 

10. Are chronic values available for acutely sensitive species? 

11. Is the range of acute-chronic ratios greater than a factor of 10? 

12. Is the Final Chronic Value reasonable in comparison with the available 

acute and chronic data? 

13. Is the measured or predicted chronic value for any commercially or 

recreationally important species below the Final Chronic Value? 

14. Are any of the other data important? 

15. Do any data look like they might be outliers? 

16. Are there any deviations from the Guidelines? Are they acceptable? 

B. On the basis of all available pertinent laboratory and field information, determine if 

the criterion is consistent with sound scientific evidence. If it is not, another criterion, 

either higher or lower, should be derived using appropriate modifications of these 

Guidelines. 

30 
31 

 

References 

1

 U.S. EPA. 1983. Water Quality Standards Regulation. Federal Register 48: 51400-51413. November 8. 

2

 U.S. EPA. 1983. Water Quality Standards Handbook. Office of Water Regulations and Standards, Washington, 

DC. 

3

 U.S. EPA. 1985. Technical Support Document for Water Quality-Based Toxics Control. Office of Water, 

Washington, DC. 

4

 Thurston, C.E. 1962. Physical Characteristics and Chemical Composition of Two Subspecies of Lake Trout. J. 

Fish. Res. Ed. Canada 19:39-44. 

5

 Hodson, P.V., et al. 1983. Effect of Fluctuating Lead Exposure on Lead Accumulation by Rainbow Trout (Salmo 

gairdneri). Environ. Toxicol. Chem. 2: 225-238. 

6

 For example, see: Ingersoll, C.G. and R.W. Winner. 1982. Effect on Daphnia pulex (De Geer) of Daily Pulse 

Exposures to Copper to Cadmium. Environ. Toxicol. Chem. 1:321-327; Seim, W.K., et al. 1984. Growth and 

Survival of Developing Steelhead Trout (Salmo gairdneri) Continuously or Intermittental Exposed to Copper. 

Can. J. Fish. Aquat. Sci. 41: 433-438; Buckley, J.T., et al. 1982. Chronic Exposure of Coho Salmon to Sublethal 

Concentrations of Copper-I. Effect on Growth, on Accumulation and Distribution of Copper, and on Copper 

Tolerance. Comp. Biochem. Physiol. 72C: 15-19; Brown, V.M., et al. 1969. The Acute Toxicity to Rainbow Trout 

of Fluctuating Concentrations and Mixtures of Ammonia Phenol and Zinc. J. Fish. Biol. 1:1-9; Thurston, R.V., et 

al. 1981. Effect of Fluctuating Exposures on The Acute Toxicity of Ammonia to Rainbow Trout (Salmo 

gairdneri) and Cutthroat Trout (S. clarkii). Water Res. 15: 911-917. 

7

 For example, see: Horning, W.B. and T.W. Neiheisel. 1979. Chronic Effect of Copper on the Bluntnose Minnow, 

Pimephales notatus (Rafinesque). Arch. Environ. Contam. Toxicol. 8:545-552. 

8

 For example, see: Chapman, G.A. 1982. Letter to Charles E. Stephan. U.S. EPA, Duluth, Minnesota. December 6; 

Chapman, G.A. 1975. Toxicity of Copper, Cadmium and Zinc to Pacific Northwest Salmonids. Interim Report. 

U.S. EPA, Corvallis, Oregon; Sephar, R.L. 1976. Cadmium and Zinc Toxicity to Flagfish, Jordanelle floridae. J. 

Fish. Res. Board Can. 33: 1939-1945. 

9

 U.S. EPA. 1980. Water Quality Criteria Documents; Availability. Federal Register 45: 79318-79379. November 

28. 

10 U.S. EPA. 1984. Water Quality Criteria; Request for Comments. Federal Register 49: 4551-4554. February 7. 

11 Erickson, R.J. and C.E. Stephan. 1985. Calculation of the Final Acute Value for Water Quality Criteria for 

Aquatic Organisms. National Technical Information Service, Springfield, Virginia. PB88-214994. 

12 U.S. Food and Drug Administration. 1981. Compliance Policy Guide. Compliance Guidelines Branch, 

Washington, DC. 

13 For good examples of acceptable procedures, see: 

ASTM Standard E 729, Practice for Conducting Acute Toxicity Tests with Fishes, Macroinvertebrates, and 

Amphibians. 

ASTM Standard E 724, Practice for Conducting Static Acute Toxicity Tests with Larvae of Four Species of 

Bivalve Molluscs. 

14 Huth, E.J., et al. 1978. Council of Biology Editors Style Manual, 4th Ed. Council of Biology Editors, Inc., 

Bethesda, Maryland. p. 117. 

15 Dixon, W.J. and M.B. Brown (eds.). 1979. BMDP Biomedical Computer Programs, P-series. University of 

California, Berkeley. pp. 521-539. 

16 Neter, J. and W. Wasserman. 1974. Applied Linear Statistical Models. Irwin, Inc., Homewood Illinois. 
 

17 The values of 0.1 and 0.2 were derived from data published in: 

McDiffett, W.F. 1970. Ecology 51: 975-988. 

Brocksen, R.W., et al. 1968. J. Wildlife Management 32: 52-75. 

Cummins, K.W., et al. 1973. Ecology 54: 336-345. 

Pesticide Analytical Manual, Volume I, Food and Drug Administration, 1969. 

Love, R.M. 1957. In: M.E. Brown (ed.), The Physiology of Fishes, Vol. I. Academic Press, New York. p.411. 

Ruttner, F. 1963. Fundamentals of Limnology, 3rd Ed. Trans. by D.G. Frey and F.E. J. Fry. University of 

Toronto Press, Toronto. 

Some additional values can be found in: 

Sculthorpe, C.D. 1967. The Biology of Aquatic Vascular Plants. Arnold Publishing, Ltd., London. 

18 Hamelink, J.L., et al. 1971. A Proposal: Exchange Equilibria Control the Degree Chlorinated Hydrocarbons are 

Biologically Magnified in Lentic Environments. Trans. Am. Fish. Soc. 100:207-214. 

19 Lunsford, C.A. and C.R. Blem. 1982. Annual Cycle of Kepone Residue in Lipid Content of the Estuarine Clam, 

Rangia cuneata. Estuaries 5: 121-130. 

20 Schnoor, J.L. 1982. Field Validation of Water Quality Criteria for Hydrophobic Pollutants. In; J.G. Pearson, et al. 

(eds.), Aquatic Toxicology and Hazard Assessment. ASTM STP 766. American Society for Testing and 

Materials, Philadelphia. Pp. 302-315. 

21 Sidwell, V.D. 1981. Chemical and Nutritional Composition of Finfishes, Whales, Crustaceans, Mollusks, and 

Their Products. NOAA Technical Memorandum NMFS F/SEC-11. National Marine Fisheries Service, Southeast 

Fisheries Center, Charleston, South Carolina. 

32 
33 

Appendix 1. Resident North American Species of Aquatic Animals 

Used in Toxicity and Bioconcentation Tests 

Introduction 

These lists identify species of aquatic animals which have reproducing wild populations in North 

America and have been used in toxicity or bioconcentration tests. "North America" includes 

only the 48 contiguous states, Canada, and Alaska; Hawaii and Puerto Rico are not included. 

Saltwater (i.e., estuarine and true marine) species are considered resident in North America if 

they inhabit or regularly enter shore waters on or above the continental shelf to a depth of 200 

meters. Species do not have to be native to be resident. Unlisted species should be considered 

resident North American species if they can be similarly confirmed or if the test organisms were 

obtained from a wild population in North America. 

The sequence for fishes is taken from A List of Common and Scientific Names of Fishes from 

the United States and Canada. For other species, the sequence of phyla, classes, and families is 

taken from the NODC Taxonomic Code, Third Edition, National Oceanographic Data Center, 

NOAA, Washington, DC 20235, July, 1981, and the numbers given are from that source to 

facilitate verification. Within a family, genera are in alphabetical order, as are species in a 

genus. 

The references given are those used to confirm that the species is a resident North American 

species. (The NODC Taxonomic Code contains foreign as well as North American species.) If 

no such reference could be found, the species was judged to be nonresident. No reference is 

given for organisms not identified to species; these are considered resident only if obtained from 

wild North American populations. A few nonresident species are listed in brackets and noted as 

"nonresident" because they were mistakenly identified as resident in the past or to save other 

investigators from doing literature searches on the same species. 

 Special Note 

This December 2010 electronic version of the 1985 Guidelines serves to meet the requirements of Section 

508 of the Rehabilitation Act. While converting the 1985 Guidelines to a 508-compliant version, EPA 

updated the taxonomic nomenclature to reflect changes that occurred since the tables were originally 

produced in 1985. The numbers included for Phylum, Class and Family represent those currently in use 

from the Integrated Taxonomic Information System, or ITIS, and reflect what is referred to in ITIS as 

Taxonomic Serial Numbers. ITIS replaced the National Oceanographic Data Center (NODC) taxonomic 

coding system which was used to create the original taxonomic tables included in the 1985 Guidelines 

document (NODC, Third Addition - see Introduction). For more information on the NODC taxonomic 

codes, see http://www.nodc.noaa.gov/General/CDR-detdesc/taxonomic-v8.html. 

The code numbers included in the reference column of the tables have not been updated from the 1985 

version. These code numbers are associated with the old NODC taxonomic referencing system and are 

simply replicated here for historical purposes. Footnotes may or may not still apply. 

EPA is working on a more comprehensive update to the 1985 Guidelines, including new taxonomic tables 

which better reflect the large number of aquatic animal species known to be propagating in U.S. waters.
Freshwater Species Table 

Synonyms appear after the official Scientific Name and are marked with an asterisk (*). 

Non-resident species are noted in the Reference column and are marked with a dagger (†

) 

Class Family Species 

Common Name Scientific Name 

Reference

Phylum: Porifera (46861)

Demospongiae 

47528 

Spongillidae 

47691 

Sponge Ephydatia fluviatilis P93 

Phylum: Cnidaria (48738)

Hydrozoa Hydra Hydra oligactis E318, P112 

48739 

Hydridae 

50844 Hydra Hydra littoralis E321, P112 

Phylum: Platyhelminthes (53963)

Planarian Dugesia dorotocephala D22 

Planarian Dugesia lugubris 

Dugesia polychroa‡

D24 

Planarian Planaria gonocephala 1

Planariidae 

54502 

Planarian Polycelis felina§ nonresident 

Turbellaria 

53964 

Dendrocoelidae 

54469 

Planarian Procotyla fluviatilis 

Dendrocoelum lacteum*

E334, P132, D63 

Phylum: Gastrotricha (57597)

Chaetonotida 

57822 

Chaetonotidae 

57823 

Gastrotrich Lepidodermella squamata 

Lepidodermella squamatum*

E413 

Phylum: Rotifera (58239)

Eurotatoria Rotifer Philodina acuticornis Y 

(Formerly Bdelloidea) 

654070 

Philodinidae 

58266 Rotifer Philodina roseola E487 

Eurotatoria Rotifer Keratella cochlearis E442, P188 

(Formerly Monogononta) 

654070 

Brachionidae 

58344 Rotifer Keratella sp. 2

Phylum: Annelida (64357)

Polychaeta 

(Formerly Archiannelida) 

64358 

Aeolosomatidae 

68423 

Worm Aeolosoma headleyi E528, P284 

Lumbriculidae 

68440 

Worm Lumbriculus variegatus E533, P290 

Tubificid worm Branchiura sowerbyi E534, P289, GG 

Tubificid worm Limnodrilus hoffmeisteri E536, GG 

Tubificid worm Quistadrilus multisetosus 

Peloscolex multisetosus*

E535, GG 

Tubificid worm Rhyacodrilus montanus GG 

Tubificid worm Spirosperma ferox 

Peloscolex ferox*

GG 

Tubificid worm Spirosperma nikolskyi 

Peloscolex variegatus*

E534, GG 

Clitellata 

(Formerly Oligochaeta) 

568832 Tubificidae 

68585 

Tubificid worm Stylodrilus heringianus GG 

 

‡

 Synonym 

§

 Non-resident species 

34 
Class Family Species 

Common Name Scientific Name 

Reference

Tubificid worm Tubifex tubifex E536, P289, GG 

Tubificid worm Varichaeta pacifica GG 

Worm Nais sp. 2 

Worm Paranais sp. 2 

Naididae 

68854 

Worm Pristina sp. 2 

Clitellata 

(Formerly Hirudinea) 

568832 

Erpobdellidea 

69438 

Leech Erpobdella octoculata Formerly nonresident

(BB16) 

Phylum: Mollusca (69458)

Viviparidae 

70304 

Snail Campeloma decisum P731, M216 

Bithyniidae 

(Amnicolidae) 

(Bulimidae) 

(Hydrobiidae) 

70745 

Snail Amnicola sp. 2 

Snail Goniobasis livescens P732 

Snail Elimia virginica 

Goniobasis virginica*

E1137 

Snail Leptoxis carinata 

Nitocris carinata*

Mudalia carinata*

X, E1137 

Pleuroceridae 

71541 

Snail Nitocris sp. 2 

Snail Lymnaea acuminata† nonresident 

Snail Lymnaea catascopium 

Lymnaea emerginata*

Stagnicola emerginata*

M328 

Snail Lymnaea elodes 

Lymnaea palustris*

E1127, M351 

Snail Lymnaea luteola† nonresident 

M266 

Snail Lymnaea stagnalis E1127, P728, M296 

Lymnaeidae 

76483 

Snail Lymnaea sp. 2 

Snail Biomphalaria glabrata Formerly nonresident

(M390) 

Snail Gyraulus circumstriatus P729, M397 

Snail Helisoma campanulatum M445 

Planorbidae 

76591 

Snail Helisoma trivolvis P729, M452 

Snail Aplexa hypnorum E1126, P727, M373 

Snail Physa fontinalis† nonresident 

M373 

Snail Physa gyrina E1126, P727, M373 

Snail Physa heterostropha M378 

Snail Physa integra P727 

Gastropoda 

69459 

Physidae 

76676 

Snail Physa sp. 2 

Margaritiferidae 

79914 

Mussel Margaritifera margaritifera E1138, P748, J11 

Unionidae 

(Formerly Amblemidae) 

79913 

Mussel Amblema plicata AA122 

Bivalvia 

(Pelecypoda) 

79118 

Unionidae Mussel Anodonta imbecillis J72, AA122 

35 
Class Family Species 

Common Name Scientific Name 

Reference

Mussel Carunculina parva 

Toxolasma texasensis*

J19, AA122 

Mussel Cyrtonaias tampicoenis P759, AA122 

79913 

Mussel Elliptio complanata J13 

Corbiculidae Asiatic clam Corbicula fluminea E1159 

81381 Asiatic clam Corbicula manilensis P749 

Fingernail clam Eupera cubensis 

Eupera singleyi*

E1158, P763, G9 

Fingernail clam Musculium transversum 

Sphaerium transversum*

M160, G11 

Pisidiidae 

Sphaeriidae*

81388 

Fingernail clam Sphaerium corneum G12 

Phylum: Arthropoda (82696)

Lynceidae 

83769 

Conchostracan Lynceus brachyurus E580, P344 

Sididae 

83834 

Cladoceran Diaphanosoma sp. 2 

Cladoceran Ceriodaphnia acanthina E618 

Cladoceran Ceriodaphnia reticulata E618, P368 

Cladoceran Daphnia ambigua E607, P369 

Cladoceran Daphnia carinata 3

Cladoceran Daphnia cucullata† nonresident 

Cladoceran Daphnia galeata mendotae E610, P370 

Cladoceran Daphnia hyalina 4

Cladoceran Daphnia longispina 5

Cladoceran Daphnia magna E605, P367 

Cladoceran Daphnia parvula E611 

Cladoceran Daphnia pulex E613, P367 

Cladoceran Daphnia pulicaria A 

Cladoceran Daphnia similis E606, P367 

Cladoceran Simocephalus serrulatus E617, P370 

Daphniidae 

83872 

Cladoceran Simocephalus vetulus E617, P370 

Moinidae Cladoceran Moina macrocopa E622, P372 

(Formerly Daphnidae) 

84162 Cladoceran Moina rectirostris E623 

Bosminidae 

83935 

Cladoceran Bosmina longirostris E624, P373 

Branchiopoda 

(Formerly Crustacea) 

83687 

Polyphemidae 

83959 

Cladoceran Polyphemus pediculus E599, P385 

Ostracod Cypretta kawatai† nonresident 

U 

Ostracoda 

(Formerly Crustacea) 

84195 

Cyprididae 

Cypridae*

84462 Ostracod Cypridopsis vidua E770, P430 

Diaptomidae 

85779 

Copepod Eudiaptomus padanus† nonresident 

Temoridae 

85855 

Copepod Epischura lacustris E751, P407 

Copepod Cyclops abyssorum† nonresident 

Copepod Cyclops bicuspidatus E807, P405 

Copepod Cyclops vernalis E804, P405 

Maxillopoda 

(Formerly Crustacea) 

621145 

Cyclopidae 

88634 

Copepod Cyclops viridis 

Acanthocyclops viridis*

E803, P397 

36 
Class Family Species 

Common Name Scientific Name 

Reference

Copepod Acanthocyclops sp. 2 

Copepod Diacyclops sp. 2 

Copepod Eucyclops agilis P403 

Copepod Mesocyclops leuckarti E812, P403 

Isopod Asellus aquaticus† nonresident (I2) 

Isopod Caecidotea bicrenata 

(Formerly Asellus bicrenata) 

HH 

(I1,2) 

Isopod Asellus brevicaudus E875, P447, I 

Isopod Asellus communis E875, P448, I 

Isopod Asellus intermedius E875, P448, I 

Isopod Asellus meridionalis†

Asellus meridianus*†

nonresident 

Isopod Asellus racovitzai P449, I 

Asellidae 

92657 

Isopod Lirceus alabamae P875, I 

Crangonyctidae 

(Formerly Gammaridae) 

95080 

Amphipod Crangonyx pseudogracilis P459, T68, FF23 

Amphipod Gammarus fasciatus E877, P458, T53 

Amphipod Gammarus lacustris E877, P458, FF23 

Amphipod Gammarus pseudolimnaeus E877, P458, T48 

Amphipod Gammarus pulex† nonresident 

Amphipod Gammarus tigrinus L51, FF17 

Gammaridae 

93745 

Amphipod Gammarus sp. 2 

Hyalellidae 

(Talitridae) 

94022 

Amphipod Hyalella azteca 

Hyalella knickerbockeri*

E876, P457, T154 

Prawn Macrobrachium lamarrei† nonresident 

Prawn Macrobrachium rosenbergii 6

Palaemonidae 

96213 

Prawn Palaemonetes kadiakensis E881, P484 

Crayfish Cambarus latimanus E897 

Crayfish Faxonella clypeata E890 

Crayfish Orconectes immunis E894, P482 

Crayfish Orconectes limosus E893, P482 

Crayfish Orconectes propinquus E894, P482 

Crayfish Orconectes nais E894 

Crayfish Orconectes rusticus E893, P482 

Crayfish Orconectes virilis E894, P483 

Crayfish Pacifastacus trowbridgii E883 

Crayfish Procambarus acutus P482 

Crayfish Procambarus clarki 

Procambarus clarkii*

E885, P482 

Crayfish Procambarus simulans E888, P482 

Malacostraca 

(Formerly Crustacea) 

89787 

Cambaridae 

(Formerly Astacidae) 

97336 

Crayfish Procambarus sp. 2 

Mayfly Maccaffertium ithaca 

Stenonema ithaca*

Heptageniidae S173, O205 

100504 

Mayfly Maccaffertium modestum 

Stenonema rubrum*

S178, O205 

Insecta 

99208 

Baetidea Mayfly Callibaetis skokianus S116, N9 

37 
Class Family Species 

Common Name Scientific Name 

Reference

100755 Mayfly Callibaetis sp. 2 

Mayfly Cloeon dipterum O173 

Leptophlebiidae 

101095 

Mayfly Paraleptophlebia praepedita S89, O233 

Mayfly Drunella doddsii 

Ephemerella doddsi*

O245 

Mayfly Drunella grandis 

Ephemerella grandis*

O245 

Mayfly Ephemerella subvaria N9, O248, S71 

Ephemerellidae 

101232 

Mayfly Ephemerella sp. 2 

Caenidea 

101467 

Mayfly Caenis diminuta S51, O268 

Mayfly Ephemera simulans S36, N9, O283 

Mayfly Hexagenia bilineata N9, S39, O290 

Mayfly Hexagenia rigida O290, S41, N9 

Ephemeridae 

101525 

Mayfly Hexagenia sp. 2 

Libellulidae 

101797 

Dragonfly Pantala hymenaea 

Pantala hymenea*

N15, V603 

Damselfly Enallagma aspersum DD 

Damselfly Ischnura elegans† nonresident 

Damselfly Ischnura verticalis N15, E918 

Coenagrionidae 

Agrionidae*

Coenagriidae*

102077 

Damselfly Ischnura sp. 2 

Stonefly Pteronarcella badia L172 

Stonefly Pteronarcys californica L173 

Stonefly Pteronarcys dorsata E947 

Pteronarcyidae 

(Formerly Pteronarcidae) 

Pleronarcyidae*

102470 

Stonefly Pteronarcys sp. 2 

Nemouridae 

102517 

Stonefly Nemoura cinerea† nonresident 

Stonefly Acroneuria lycorias N4, E953 

Stonefly Acroneuria pacifica E953, L180 

Stonefly Claassenia sabulosa E953 

Perlidae 

102914 

Stonefly Agnetina capitata 

Neophasganophora capitata*

Phasganophora capitata*

E953, CC407 

Perlodidae 

102994 

Stonefly Skwala americana 

Arcynopteryx parallela*

E954 

Nepidae 

103747 

Water Scorpion Ranatra elongate†

(Species cannot be confirmed in 

ITIS)

nonresident 

Dytiscidae 

111963 

Beetle - 2 

Elmidae 

Elminthidae*

114093 

Beetle Stenelmis sexlineata W21 

Caddisfly Arctopsyche grandis L251, II98 

Caddisfly Hydropsyche betteni N24 

Caddisfly Hydropsyche californica L253 

Hydropsychidae 

115398 

Caddisfly Hydropsyche sp. 2 

Limnephilidae Caddisfly Clistoronia magnifica II206 

115933 Caddisfly Philarctus quaeris II272 

38 
Class Family Species 

Common Name Scientific Name 

Reference

Brachycentridae 

116905 

Caddisfly Brachycentrus sp. 2 

Tipulidae 

118840 

Crane fly Tipula sp. 2 

Ceratopogonidae 

127076 

Biting midge - 2 

Culicidae Mosquito Aedes aegypti EE3 

125930 Mosquito Culex pipiens EE3 

Midge Chironomus plumosus 

Tendipas plumosus*

L423 

Midge Chironomus tentans Q 

Midge Chironomus thummi† nonresident 

Midge Chironomus sp. 2 

Midge Paratanytarsus parthenogeneticus 7

Chironomidae 

127917 

Midge Paratanytarsus dissimilis 

Tanytarsus dissimilis*

R11 

Athericidae 

(Formerly Rhagionidae) 

Leptidae*

130928 

Snipe fly Atherix sp. 2 

Phylum: Ectoprocta (155470)

Pectinatellidae 

(Formerly 

Pectinatelcidae) 

156729 

Bryozoan Pectinatella magnifica E502, P269 

Lophopodidae 

156714 

Bryozoan Lophopodella carteri E502, P2671 

Phylactolaemata 

156688 

Plumatellidae 

156690 

Bryozoan Plumatella emarginata E505, P272 

Phylum: Chordata (158852)

Agnatha 

159693 

Petromyzontidae 

159697 

Sea lamprey Petromyzon marinus F11 

Anguillidae 

161125 

American eel Anguilla rostrata F15 

Pink salmon Oncorhynchus gorbuscha F18 

Coho salmon Oncorhynchus kisutch F18 

Sockeye salmon Oncorhynchus nerka F19 

Chinook Salmon Oncorhynchus tshawytscha F19 

Mountain whitefish Prosopium williamsoni F19 

Golden Trout Oncorhynchus aguabonita 

(Formerly Salmo aguabonita) 

F19 

Cutthroat trout Oncorhynchus clarki 

(Formerly Salmo clarki) 

F19 

Rainbow trout 

Steelhead trout*

Oncorhynchus mykiss 

(Formerly Salmo gairdneri) 

F19 

Atlantic salmon Salmo salar F19 

Brown trout Salmo trutta F19 

Brook trout Salvelinus fontinalis F19 

Actinopterygii 

(Formerly Osteichthyes) 

161061 Salmonidae 

161931 

Lake trout Salvelinus namaycush F19 

39 
Class Family Species 

Common Name Scientific Name 

Reference

Esocidae 

162137 

Northern pike Esox lucius F20 

Chiselmouth Acrocheilus alutaceus F21 

Longfin dace Agosia chrysogaster F21 

Central stoneroller Campostoma anomalum F21 

Goldfish Carassius auratus F21 

Common carp Cyprinus carpio F21 

Zebra danio 

Zebrafish

*

Danio rerio

†

Brachydanio rerio

*

†

nonresident 

F96 

Silverjaw minnow Notropis buccatus 

Ericymba buccata

*

F21 

Golden shiner Notemigonus crysoleucas F23 

Pugnose shiner Notropis anogenus F23 

Emerald shiner Notropis atherinoides F23 

Striped shiner Luxilus chrysocephalus 

Notropis chrysocephalus

*

F23 

Common shiner Luxilus cornutus 

Notropis cornutus

*

F23 

Pugnose minnow Opsopoeodus emiliae 

Notropis emiliae

*

F24 

Spottail shiner Notropis hudsonius F24 

Red shiner Cyprinella lutrensis 

Notropis lutrensis

*

F24 

Spotfin shiner Cyprinella spiloptera 

Notropis spilopterus

*

F25 

Sand shiner Notropis stramineus F25 

Steelcolor shiner Cyprinella whipplei 

Notropis whipplei

*

F25 

Northern redbelly dace Phoxinus eos F25 

Bluntnose minnow Pimephales notatus F25 

Fathead minnow Pimephales promelas F25 

Northern squawfish Ptychocheilus oregonensis F25 

Blacknose dace Rhinichthys atratulus F25 

Speckled dace Rhinichthys osculus F25 

Bitterling Rhodeus sericeus F26 

Rudd Scardinius erythrophthalmus F26 

Creek chub Semotilus atromaculatus F26 

Pearl dace Margariscus margarita 

Semotilus margarita

*

F26 

Cyprinidae 

163342 

Tench Tinca tinca F26 

Catostomidae White sucker Catostomus commersoni F26 

163892 Mountain sucker Catostomus platyrhynchus F26 

Black bullhead Ameiurus melas 

Ictalurus melas

*

F27 

Yellow bullhead Ameiurus natalis 

Ictalurus natalis

*

F27 

Brown bullhead Ameiurus nebulosus 

Ictalurus nebulosus

*

F27 

Ictaluridae 

163995 

Channel catfish Ictalurus punctatus F27 

40 
Class Family Species 

Common Name Scientific Name 

Reference

Clariidae 

164118 

Walking catfish Clarias batrachus F28 

Adrianichthyidae 

(Formerly Oryziidae) 

165623 

Medaka Oryzias latipe† nonresident 

F96 

Cyprinodontidae Banded killifish Fundulus diaphanus F33 

165629 Flagfish Jordanella floridae F33 

Mosquitofish Gambusia affinis F33 

Amazon molly Poecilia formosa F34 

Sailfin molly Poecilia latipinna F34 

Molly Poecilia sp. 

Guppy Poecilia reticulata 

(Lebistes reticulatus, Obs.) 

F34 

Poeciliidae 

165876 

Southern platyfish Xiphophorus maculatus F34 

Brook stickleback Culaea inconstans F35 

Threespine stickleback Gasterosteus aculeatus F35 

Gasterosteidae 

166363 

Ninespine stickleback Pungitius pungitius F35 

White perch Morone americana 

(Roccus americanus, Obs.) 

Percichthyidae F36 

170315 

Striped bass Morone saxatilis 

(Roccus saxatilis, Obs.) 

F36 

Rock bass Ambloplites rupestris F38 

Green sunfish Lepomis cyanellus F38 

Pumpkinseed Lepomis gibbosus F38 

Orangespotted sunfish Lepomis humilis F38 

Bluegill Lepomis macrochirus F38 

Longear sunfish Lepomis megalotis F38 

Redear sunfish Lepomis microlophus F38 

Smallmouth bass Micropterus dolomieui F39 

Largemouth bass Micropterus salmoides F39 

White crappie Pomoxis annularis F39 

Centrarchidae 

168093 

Black crappie Pomoxis nigromaculatus F39 

Rainbow darter Etheostoma caeruleum F39 

Johnny darter Etheostoma nigrum F40 

Orangethroat darter Etheostoma spectabile F40 

Yellow perch Perca flavescens F41 

Percidae 

168356 

Walleye Sander vitreus 

Stizostedion vitreum vitreum*

F41 

Sciaenidae 

169237 

Freshwater drum Aplodinotus grunniens F45 

Oscar Astronotus ocellatus F47 

Blue tilapia Tilapia aurea F47 

Cichlidae 

169770 

Mozambique tilapia Oreochromis mossambicus 

Tilapia mossambica*

F47 

Cottidae 

167196 

Mottled sculpin Cottus bairdi F60 

Amphibia Bullfrog Rana catesbeiana B206 

173420 

Ranidae 

173433 Green frog Rana clamitans B206 

41 
42 

Class Family Species 

Common Name Scientific Name 

Reference

Pig frog Lithobates grylio 

Rana grylio*

B206 

River frog Rana heckscheri B206 

Leopard frog Rana pipiens B205 

Wood frog Rana sylvatica B206 

Frog Rana temporia† nonresident 

Leopard frog Lithobates sphenocephalus 

sphenocephalus 

(Formerly Rana spenocephala) 

JJ 

Microhylidae 

173465 

Eastern narrowmouthed 

toad 

Gastrophryne carolinensis B192 

American toad Anaxyrus americanus americanus 

Bufo americanus*

B196 

Toad Bufo bufo† nonresident 

Green toad Anaxyrus debilis debilis 

Bufo debilis*

B197 

Fowler's toad Anaxyrus fowleri 

Bufo fowleri*

B196 

Red-spotted toad Anaxyrus punctatus 

Bufo punctatus*

B198 

Bufonidae 

173471 

Woodhouse's toad Anaxyrus woodhousii woodhousii 

Bufo woodhousii*

B196 

Northern cricket frog Acris crepitans B203 

Southern gray treefrog Hyla chrysoscelis B201 

Spring creeper Pseudacris crucifer 

Hyla crucifer*

B202 

Barking treefrog Hyla gratiosa B201 

Squirrel treefrog Hyla squirella B201 

Gray treefrog Hyla versicolor B200 

Hylidae 

173497 

Northern chorus frog Pseudacris triseriata B202 

Pipidae 

173547 

African clawed frog Xenopus laevis Z16 

Spotted salamander Ambystoma maculatum B176 

Mexican axolotl Ambystoma mexicanum† nonresident 

Ambystomatidae 

173588 

Marbled salamander Ambystoma opacum B176 

Salamandridae 

173613 

Newt Notophthalmus viridescens 

Triturus viridescens*

B179 

Footnotes for Freshwater Species

 

1

 Apparently this is an outdated name (D19, 20). Organisms identified as such should only be used if they were obtained from 

North America. 

2

 Apparently this is an outdated name (D19, 20). Organisms identified as such should only be used if they were obtained from 

North America. 

3

 If from North America, it is resident and should be called D. similis (C). If not from North America, it should be considered 

nonresident. 

4

 If from North America, it is resident and may be any one of a number of species such as D. laevie, D. dubia, or D. galeate 

mendoca (C). If not from North America, it should be considered nonresident. 
 

5

 If from North America, it is resident and may be any one of a number of species such as D. ambigua, D. longiremis, or D. rosea

(C). If not from North America, it should be considered nonresident. 

6

 This species might be established in portions of the southern United States. 

7

 The taxonomy of this species and this and similar genera has not been clarified, but this species should be considered resident. 

References for Freshwater Species 

A) Brandlova, J., Z. Brandl, and C.H. Fernando. 1972. The Cladocera of Ontario with remarks on some species 

and distribution. Can. J. Zool. 50: 1373-1403. 

B) W. F., et al. 1968. Vertebrates of the United States. 2nd Ed. McGraw-Hill, New York. 

C) Brooks, J.L. 1957. The Systematics of North American Daphnia. Memoirs of the Connecticut Academy of 

Arts and Sciences, Vol. XIII. 

D) Kenk, R. 1972. Freshwater Planarians (Turbellaria) of North America. Biota of Freshwater Ecosystems 

Identification Manual No. 1. U.S. G.P.O #5501-0365. 

E) Edmondson, W.T. (ed.) 1965. Fresh-water Biology. 2nd Ed. Wiley, New York. 

F) Committee on Names of Fishes. 1980. A List of Common and Scientific Names of Fishes from the United 

States and Canada. 4th Ed. Special Publication No. 12. American Fisheries Society. Bethesda, MD. 

G) Burch, J.B. 1972. Freshwater Sphaeriacean Clams (Mollusca: Pelecypoda) of North America. Biota of 

Freshwater Ecosystems Identification Manual No. 3. U.S. G.P.O. #5501-0367. 

H) N. 1972. Freshwater Polychaetes (Annelida) of North America. Biota of Freshwater Ecosystems 

Identification Manual No. 4. U.S. G.P.O. #5501-0368. 

I) Williams, W. D. 1972. Freshwater Isopods (Asellidae) of North America. Biota of Freshwater Ecosystems 

Identification Manual No. 7. U.S. G.P.O. #5501-0390. 

J) Burch, J. B. 1973. Freshwater Unionacean Clams (Mollusca: Pelecypoda) of North America. Biota of 

Freshwater Ecosystems Identification Manual No. 11. ‘U.S. G.P.O. #5501-00588. 

K) Kudo, R. R. 1966. Protozoology. 5th Ed. Thomas, Springfield, Illinois. 

L) Usinger, R. L. 1956. Aquatic Insects of California. University of California Press, Berkeley. 

M) Clarke, A. H. 1973. The Freshwater Molluscs of the Canadian Interior Basin. Malacologia 13: l-509. 

N) Hilsenhoff, W.L. 1975. Aquatic Insects of Wisconsin. Technical Bulletin No. 89. Dept. of Natural Resources. 

Madison, Wisconsin. 

O) Edmunds, G. F., Jr., et al. 1976. The Mayflies of North and Central America. University of Minnesota Press, 

Minneapolis. 

P) Pennak, R. W. 1978. Fresh-Water Invertebrates of the United States. 2nd Ed. Wiley, New York. 

Q) Wentsell, R., et al. 1977. Hydrobiologia 56: 153-156. 

R) Johannsen, O.A. 1937. Aquatic Diptera. Part IV. Chironomidae: Subfamily Chironominal. Memoir 210. 

Cornell Univ. Agricultural Experimental Station, Ithaca, NY. 

S) Burks, B.D. 1953. The Mayflies, or Ephemeroptera, of Illinois. Bulletin of the Natural History Survey 

Division. Urbana, Illinois. 

43 
44 

T) Bousfield, E.L. 1973. Shallow-Water Gammaridean Amphipods of New England. Cornell University Press, 

Ithaca, New York. 

U) Sohn, I. G., and L. S. Kornicker. 1973. Morphology of Cypretta kawatai Sohn and Kornicker, 1972 

(Crustacea, Ostracoda), with a Discussion of the Genus. Smithsonian Contributions to Zoology, No. 141. 

V) Needham, J. G., and M. J. Westfall, Jr. 1955. A Manual of the Dragonflies of North America. Univ. of 

California Press, Berkeley. 

W) Brown, H. P. 1972. Aquatic Dryopoid Beetles (Coleoptera) of the United States. Biota of Freshwater 

Ecosystems Identification Manual No. 6. U.S.G.P.O. #5501-0370. 

X) Parodiz, J.J. 1956. Notes on the Freshwater Snail Leptoxis (Mudalia) carinata (Bruguiere). Annals of the 

Carnegie Museum 33: 391-405. 

Y) Myers, F.J. 1931. The Distribution of Rotifera on Mount Desert Island. Am. Museum Novitates 494: l-12. 

Z) National Academy of Sciences. 1974. Amphibians : Guidelines for the breeding, care, and management of 

laboratory animals. Washington, D.C. 

AA) Horne, F.R., and S. McIntosh. 1979. Factors Influencing Distribution of Mussels in the Blanco River in 

Central Texas. Nautilus 94: 119-133. 

BB) Klemm, D. J. 1972. Freshwater Leeches (Annelida: Hirudinea) of North America. Biota of Freshwater 

Ecosystems Identification Manual No. 8. U.S.G.P.O. #5501-0391. 

CC) Frison, T. H. 1935; The Stoneflies, or Plecoptera, of Illinois. Bull. Ill. Nat. History Survey, Vol. 20, Article 4. 

DD) White, A. M. Manuscript. John Carroll University, University Heights, Ohio. 

EE) Darsie, R.F., Jr., and R.A. Ward. 1981. Identification and Geographical Distribution of the Mosquitoes of 

North America, North of Mexico. American Mosquito Control Association, Fresno, California. 

FF) Holsinger, J.R. 1972. The Freshwater Amphipod Crustaceans (Gammaridae) of North America. Biota of 

Freshwater Ecosystems Identification Manual No. 5. U.S.G.P.O. #5501-0369. 

GG) Chapman, P. H., et al. 1982. Relative Tolerances of Selected Aquatic Oligochaetes to Individual Pollutants 

and Environmental Factors. Aquatic Toxicology 2: 47-67. 

HH) Bosnak, A.D., and E.L. Morgan. 1981. National Speleological Society Bull. 43: 12-18. 

II) Wiggens, G.B. 1977. Larvae of the North American Caddisfly Genera (Tricoptera). University of Toronto 

Press, Toronto, Canada. 

JJ) Hall, R. J. and D. Swineford. 1980. Toxic Effects of Endrin and Toxaphene on the Southern Leopard Frog 

Rana sphenocephala. Environ. Pollut. (Series A) 23: 53-65.
45 

Saltwater Species Table 

Synonyms appear after the official Scientific Name and are marked with an asterisk (*). 

Non-resident species are noted in the Reference column and are marked with a dagger (†

) 

Class Family Species 

Common Name Scientific Name 

Reference

Phylum: Cnidaria (Coelenterata) (48738) 

Hydroid Campanularia flexiosa 

Campanularia flexuosa**

B122, E81 

Hydroid Laomedea loveni†† nonresident 

Campanulariidae 

49470 

Hydromedusa Phialidium sp. 1

(E81) 

Hydroza 

48739 

Campanulinidae 

49756 

Hydroid Eirene viridula† nonresident 

Phylum: Ctenophora (53856)

Pleurobrachiidae 

53860 

Tentaculata Ctenophore Pleurobrachia pileus B218, E162 

53858 

Mnemiidae 

53915 

Ctenophore Mnemiopsis mccradyi C39, I94 

Phylum: Nemertea (Rhynchocoela) (57411)

Heteronemertea 

57438 

Lineidae 

57443 

Nemertine worm Cerebratulus fuscus B252 

Phylum: Rotifera (Rotatoria) (58239)

Monogononta 

58342 

Brachionidae 

58344 

Rotifer Brachionus plicatilis B272 

Phylum: Annelida (64357)

Phyllodocidae 

65228 

Polychaete worm Phyllodoce maculata 

Anaitides maculata*

Nereiphylla maculata*

E334 

Polychaete worm Neanthes arenaceodentata 

Nereis arenaceodentata*

E377 

Polychaete worm Neanthes vaali† nonresident 

Polychaete worm Nereis diversicolor 

Neanthes diversicolor*

E337, F527 

Sand worm Nereis virens 

Neanthes virens*

B317, E337, C58 

Nereididae 

(Nereidae) 

65870 

Polychaete worm Nereis sp. 

Dorvilleidae Polychaete worm Ophryotrocha diadema P23 

66478 

Polychaete worm Ophryotrocha labronica†

Ophryotrocha labrunica*†

nonresident 

Spionidae 

66781 

Polychaete worm Polydora websteri E338 

Cirratulidae 

67116 

Polychaete worm Cirriformia spirabranchia G253 

Ctenodrilidae 

67217 

Polychaete worm Ctenodrilus serratus G275 

Capitellidae 

67413 

Polychaete worm Capitella capitata B358, E337 

Polychaeta 

64358 

Arenicolidae 

67500 

Polychaete worm Arenicola marina B369, E337 

 

** Synonym 

†† Non-resident species 
46 

Class Family Species 

Common Name Scientific Name 

Reference

Sabellidae 

68076 

Polycheate worm Eudistylia vancouveri DD 

Oligochaete worm Limnodriloides verrucosus Z 

Oligochaete worm Monopylephorus cuticulatus Z 

Oligochaeta 

68422 

Tubificidae 

68585 

Oligochaete worm Peloscolex gabriellae 

Tubificoides gabriellae*

Z 

Phylum: Mollusca (69458)

Haliotididae Black abalone Haliotis cracherodii C88, D17 

566897 Red abalone Haliotis rufescens D18 

Calyptraeidae 

72611 

Common Atlantic 

slippershell 

Crepidula fornicata C90, D141 

Muricidae 

73236 

Oyster drill Urosalpinx cinerea 

Urosalpinx cinereus*

B646, D179, E264 

Melongenidae 

(Neptuneidae) 

74069 

Channeled whelk Busycotypus canaliculatus 

(Formerly Busycon canaliculatum) 

B655, D223, E264 

Gastropoda 

69459 

 

Nassariidae 

(Nassidae) 

74102 

Mud snail Nassarius obsoletus 

Nassa obsoleta*

Icyanassa obsoleta*

B649, D226, E264 

Northern horse mussel Modiolus modiolus D434 

Blue mussel Mytilus edulis B566, C101, D428, 

E299 

Mytilidae 

79451 

Mediterranean mussel Mytilus galloprovincialis† nonresident 

Pectinidae 

79611 

Bay scallop Argopecten irradians D447 

Pacific oyster Crassostrea gigas C102, D456, E300 

Eastern oyster Crassostrea virginica D456, E300 

Oyster Crassostrea sp. 1 

Ostreidae 

79866 

Oyster Ostrea edulis E300 

Cardiidae 

80865 

Cockle Cerastoderma edule†

Cardium edule*†

nonresident 

Clam Mulinia lateralis D491 

Common rangia Rangia cuneata D491, E301 

Mactridae 

80942 

Surf clam Spisula solidissima B599, D489, E301 

Tellinidae Clam Macoma inquinata D507 

81032 Bivalve Tellina tenuis† nonresident 

Quahog clam Mercenaria mercenaria D523, E301 

Common Pacific littleneck Protothaca staminea D526 

Veneridae 

81439 

Japanese littleneck clam Tapes philippinarum D527 

Bivalvia 

(Pelecypoda) 

79118 

Myidae 

81688 

Soft-shell clam Mya arenaria B602, D536, E302 

Phylum: Arthropoda (82696)

Merostomata 

82698 

Limulidae 

82701 

Horseshoe crab Limulus polyphemus B533, E403, H30 

Branchiopoda 

(Formerly Crustacea) 

83687 

Artemiidae 

83689 

Brine shrimp Artemia salina† 2

nonresident 

Calanidae Copepod Calanus helgolandicus Q25 

85259 Copepod Undinula vulgaris Q29 

Eucalanidae Copepod Eucalanus elongatus AA 

85299 Copepod Subeucalanus pileatus 

Eucalanus pileatus*

AA 

Maxillopoda 

(Formerly Crustacea) 

621145 

Pseudocalanidae 

85351 

Copepod Pseudocalanus minutus E447, I155, Q43 
47 

Class Family Species 

Common Name Scientific Name 

Reference

Euchaetidae 

85524 

Copepod Euchaeta marina Q63 

Metridinidae 

(Formerly Metridiidae) 

593501 

Copepod Metridia pacifica X179, Y 

Pseudodiaptomidae 

85847 

Copepod Pseudodiaptomus coronatus E447, I154, Q101 

Temoridae 

85855 

Copepod Eurytemora affinis E450, I155, Q111 

Pontellidae 

86038 

Copepod Labidocera scotti R157 

Acartiidae Copepod Acartia clausi E447 

86083 Copepod Acartia tonsa E447, I154 

Harpacticidae Copepod Tigriopus californicus J78 

86329 Copepod Tigriopus japanicus† nonresident 

Tisbidae 

86444 

Copepod Tisbe holothuriae BB 

Ameiridae 

(Formerly 

Canthocamptidae) 

86999 

Copepod Nitokra spinipes 

Nitocra spinipe*

Q240 

Archaeobalanidae 

(Formerly Balanidae) 

89681 

Barnacle Semibalanus balanoides 

Balanus balanoides*

B424, E457 

Barnacle Balanus crenatus B426, E457 

Barnacle Balanus eburneus B424, E457 

Balanidae 

89599 

Barnacle Balanus improvisus B426, E457 

Mysid Heteromysis formosa E513, K720 

Mysid Americamysis bahia 

Mysidopsis bahia*

U173 

Mysid Americamysis bigelowi 

Mysidopsis bigelowi*

E513, K720 

Mysidae 

89856 

Mysid Neomysis sp. 1 

Isopod Idotea balthica 

Idothea baltica*

B446, E483 

Isopod Idotea emarginata† nonresident 

Idoteidae 

92564 

Isopod Idotea neglecta† nonresident 

Isopod Jaera albifrons† nonresident 

Isopod Jaera albifrons sensu† nonresident 

Janiridae 

92810 

Isopod Jaera nordmanni† nonresident 

Ampeliscidae 

93320 

Amphipod Ampelisca abdita E488, L136 

Eusiridae 

(Pontogeneiidae) 

93681 

Amphipod Pontogeneia sp. 1 

Amphipod Gammarus duebeni L56 

Amphipod Gammarus oceanicus E489, L50 

Amphipod Gammarus tigrinus L51 

Amphipod Gammarus zaddachi† nonresident 

Gammaridae 

93745 

Amphipod Marinogammarus obtusatus L58 

Uristadae 

(Formerly Lysianassidae) 

621432 

Amphipod Anonyx sp. 1 

Euphausiidae 

(Thysanopodidae) 

95500 

Euphausiid Euphausia pacifica M15 

Malacostraca 

(Formerly Crustacea) 

89787 

Penaeidae Brown shrimp Penaeus aztecus E518, N17 
48 

Class Family Species 

Common Name Scientific Name 

Reference

Pink shrimp Penaeus duorarum E518, N17 

White shrimp Penaeus setiferus E518, N17 

95602 

Blue Shrimp Penaeus stylirostris† nonresident 

Shrimp Leander paucidens† nonresident 

Prawn Leander squilla†

Palaemon elegans*†

nonresident 

Prawn Macrobrachium rosenbergii 3

Korean shrimp Palaemon macrodactylus T380 

Grass shrimp Palaemonetes pugio E521, N59 

Palaemonidae 

96213 

Grass shrimp Palaemonetes vulgaris B500, E521, N56 

Hippolytidae 

96746 

Sargassum shrimp Latreutes fucorum N78 

Coon stripe shrimp Pandalus danae T306, W163 

Shrimp Pandalus goniurus W163 

Pandalidae 

96965 

Pink shrimp Pandalus montagui B494, E522, W163 

Sand shrimp Crangon crangon† nonresident 

Bay shrimp Crangon franciscorum 

Crago franciscorum*

V176, W164 

Shrimp Crangon nigricauda V176, W164 

Crangonidae 

97106 

Sand shrimp Crangon septemspinosa B500, E522 

Nephropidae American lobster Homarus americanus B502, E532 

(Homaridae) 

97307 European lobster Homarus gammarus† nonresident 

Paguridae 

97774 

Hermit crab Pagurus longicarpus B514, E537, N125 

Cancridae Rock crab Cancer irroratus B518, E543, N175 

98670 Dungeness crab Cancer magister T166, V185, W177 

Blue crab Callinectes sapidus B521, C80, E543, 

N168 

Portunidae 

98689 

Green crab Carcinus maenas C80, E543 

Mud crab Eurypanopeus depressus B522, E543, N195 

Crab Leptodius floridanus S80 

Xanthidae 

(Pilumnidae) 

98748 

Mud crab Rhithropanopeus harrisii E543, N187 

Varunidae Shore crab Hemigrapsus nudus CC 

(formerly Grapsidae) 

621521 Shore crab Hemigrapsus oregonensis CC 

Drift line crab Armases cinereum 

(Sesarma cinereum) 

Sesarmidae B526, E544, N222 

(formerly Grapsidae) 

621520 Crab Sesarma haematocheir† nonresident 

Ocypodidae 

99080 

Fiddler crab Uca pugilator B526, E544, N232 

Phylum: Echinodermata (156857)

Asteroidea 

156862 

Asteriidae 

157212 

Starfish Asterias forbesi B728, E578, O392 

Ophiuroidea 

157325 

Ophiothricidae 

157792 

Brittle star Ophiothrix spiculata O672, T526 

Sea urchin Arbacia lixula† Arbaciidae nonresident 

157904 Sea urchin Arbacia punctulata B762, E572 

Toxopneustidae Sea urchin Lytechinus pictus T253 

157919 Sea urchin Pseudocentrotus depressus† nonresident 

Echinidae 

157940 

[chinoderm Paracentrotus lividus† nonresident 

Echinoidea 

157821 

Echinometridae 

157955 

Coral reef echinoid Echinometra mathaei† nonresident 

[Hawaii only] 
49 

Class Family Species 

Common Name Scientific Name 

Reference

Strongylocentrotidae 

157965 

Sea urchin Strongylocentrotus purpuratus O574, T202 

Dendrasteridae 

158008 

Sand dollar Dendraster excentricus O537, V363 

Phylum: Chaetognatha (158650)

Sagittoidea 

158655 

Sagittidae 

158726 

Arrow worm Ferosagitta hispida 

Sagitta hispida*

E218 

Phylum: Chordata (158852)

Chondrichthyes 

159785 

Rajidae 

160845 

Thornback ray Raja clavata† nonresident 

Anguillidae 

161125 

American eel Anguilla rostrata A15 

Atlantic menhaden Brevoortia tyrannus A17 

Gulf menhaden Brevoortia patronus A17 

Atlantic herring Clupea harengus 

Clupea harengus harengus*

A17 

Pacific herring Clupea pallasii 

Clupea harengus pallasii*

A17 

Clupeidae 

161700 

Herring Clupea harengus A17 

Engraulidae Northern anchovy Engraulis mordax A18 

553173 Nehu Encrasicholina purpurea†

tolephorus purpureus*†

nonresident 

[Hawaii only] 

Pink salmon Oncorhynchus gorbuscha A18 

Chum salmon Oncorhynchus keta A18 

Coho salmon Oncorhynchus kisutch A18 

Sockeye salmon Oncorhynchus nerka A19 

Chinook salmon Oncorhynchus tshawytscha A19 

Rainbow trout 

(Steelhead trout) 

Oncorhynchus mykiss 

(Formerly Salmo gairdneri) 

A19 

Salmonidae 

161931 

Atlantic salmon Salmo salar A19 

Gadidae Atlantic cod Gadus morhua A30 

164701 Haddock Melanogrammus aeglefinus A30 

Sheepshead minnow Cyprinodon variegatus A33 

Mummichog Fundulus heteroclitus A33 

Striped killifish Fundulus majalis A33 

Cyprinodontidae 

165629 

Longnose killifish Fundulus similis A33 

Poeciliidae Mosquitofish Gambusia affinis A33 

165876 Sailfin molly Poecilia latipinna A34 

Inland silverside Menidia beryllina A34 

Atlantic silverside Menidia menidia A34 

Atherinidae 

165984 

Tidewater silverside Menidia peninsulae A34 

Gasterosteidae Threespine stickleback Gasterosteus aculeatus A35 

166363 Fourspine stickleback Apeltes quadracus A35 

Syngnathidae 

166443 

Northern pipefish Syngnathus fuscus A36 

Percichthyidae 

170315 

Striped bass Morone saxatilis 

(Roccus saxatilis, Obs.) 

A36 

Kuhliidae 

168083 

Mountain bass Kuhlia sandvicensis† nonresident 

[Hawaii only] 

Actinopterygii 

(Formerly Osteichthyes) 

161061 

Carangidae 

168584 

Florida Pompano Trachinotus carolinus A43 
50 

Class Family Species 

Common Name Scientific Name 

Reference

Sparidae 

169180 

Pinfish Lagodon rhomboides A45 

Spot Leiostomus xanthurus A46 

Atlantic croaker Micropogonias undulatus A46 

Sciaenidae 

169237 

Red drum Sciaenops ocellatus A46 

Embiotocidae Shiner perch Cymatogaster aggregata A47 

169735 Dwarf perch Micrometrus minimus A48 

Pomacentridae 

170044 

Blacksmith Chromis punctipinnis A48 

Labridae Cunner Tautogolabrus adspersus A49 

170477 Bluehead Thalassoma bifasciatum A49 

Mullet Aldrichetta forsteri† nonresident 

Striped mullet Mugil cephalus A49 

Mugilidae 

170333 

White mullet Mugil curema A49 

Ammodytidae 

171670 

Pacific sand lance Ammodytes hexapterus A53 

Gobiidae Longjaw mudsucker Gillichthys mirabilis A54 

171746 Naked goby Gobiosoma bosci A54 

Cottidae 

167196 

Tidepool sculpin Oligocottus maculosus A61 

Bothidae Speckled sanddab Citharichthys stigmaeus A64 

172714 Summer Flounder Paralichthys dentatus A64 

Dab Limanda limanda† nonresident 

Plaice Pleuronectes platessa† nonresident 

English sole Parophrys vetulus A65 

Pleuronectidae 

172859 

Winter flounder Pseudopleuronectes americanus A65 

Balistidae 

173128 

Planehead filefish Monacanthus hispidus A66 

Tetraodontidae 

173283 

Northern puffer Sphoeroides maculatus A66 
51 

 

Footnotes for Saltwater Species

1

 Organisms not identified to species are considered resident only if obtained from wild populations in North America. 

2

 This species should not be used because it might be too atypical. 

3

 This species might be established in portions of the southern United States.

References for Saltwater Species 

A) Committee on Names of Fishes. 1980. A List of Common and Scientific Names of Fishes from the United 

States and Canada. 4th Ed. Special Publication No. 12. American Fisheries Society, Bethesda, MD. 

B) Miner, R. W. 1950. Field Book of Seashore Life. Van Rees Press, New York. 

C) George, D., and J. George. 1979. Marine Life: An Illustrated Encyclopedia of Invertebrates in the Sea. WileyInterscience, New York. 

D) Abbott, R.T. 1974. American Seashells. 2nd Ed. Van Nostrand Reinhold Company, New York. 

E) Gosner, K.L. 1971. Guide to Identification of Marine and Estuarine Invertebrates: Cape Hatteras to the Bay of 

Fundy. Wiley-Interscience, New York; Gosner, K.L. 1979. A Field Guide to the Atlantic Seashore. Houghton 

Mifflin, Boston. 

F) Hartmann, O. 1968. Atlas of the Errantiate Polychaetous Annelids from California. Allan Hancock 

Foundation, University of Southern California, Los Angeles, California. 

G) Hartmann, O. 1969. Atlas of the Sedentariate Polychaetous Annelids from California. Allan Hancock 

Foundation, University of Southern California, Los Angeles, California. 

H) Cooley, N.R. 1978. An Inventory of the Estuarine Fauna in the Vicinity of Pensacola, Florida. Florida Marine 

Research Publication No. 31. Florida Department of Natural Resources, St. Petersburg, Florida. 

I) Zingmark, R.G. (ed.) 1978. An Annotated Checklist of the Biota of the Coasta1 Zone of South Carolina. 

University of South Carolina Press, Columbia, South Carolina. 

J) Monk, C.R. 1941. Marine Harpacticoid Copepods from California. Trans. Amer. Microsc. Soc. 60:75-99. 

K) Wigley, R. , and B.R. Burns. 1971. Distribution and Biology of Mysids (Crustacea, Mysidacea) from the 

Atlantic Coast of the United States in the NMFS Woods Hole Collection. Fish. Bull. 69(4):717-746. 

L) Bousfield, E.L. 1973. Shallow-Water Gammaridean Amphipoda of New England. Cornell University Press. 

Ithaca, New York. 

M) Ponomareva, L.A. Euphausids of the North Pacific, their Distribution, and Ecology. Jerusalem: Israel 

Program for Scientific Translations. 1966. Translated from the Russian by S. Nemchonok. TT65-50098. 

NTIS, Springfield, VA. 

N) Williams, A.B. 1965. Marine Decapod Crustaceans of the Carolinas. Fish. Bull. 65(1):1-298. 

O) Hyman, L.H. 1955. The Invertebrates: Echinodermata. Vol. IV. McGraw-Hill, New York. 

P) Akesson, B. 1976. Morphology and Life Cycle of Ophryotrocha diadema, a New Polychaete Species from 

California. Ophelia 15(1): 23-25. 

Q) Wilson, C.B. 1932. The Copepods of the Woods Hole Region, Massachusetts. U.S. Nat. Mus. Bull. 158: 1-

635. 

R) Fleminger, A. 1956. Taxonomic and Distributional Studies on the Epiplanktonic Calanoid Copepods 

(Crustacea) of the Gulf of Mexico. Dissertation. Harvard University, Cambridge. 

S) Menzel, R.W. 1956. Annotated Checklist of the Marine Fauna and Flora of the St. George ’s Sound - 

Apalachee Bay region, Florida Gulf Coast. Contrib. No. 61. Fla. State Univ. Oceanogr. Inst. 
T) Ricketts, E.F., and J. Calvin. (Revised by Joe1 W. Hedgpeth). 1968. Between Pacific Tides. Stanford 

University Press, Stanford, California. 

U) Price, W.W. 1978. Occurrence of Mysidopsis almyra Bowman, M. bahia Molenock and Bowmaniella 

brasiliensis Bacescu (Crustacea, Mysidacea) from the Eastern Gulf of Mexico. Gulf Res. Reports 6(2): 173-

175. 

V) Light, S.F. (Revised by R.I. Smith, et a1.). 1961. Intertidal Invertebrates of the Central California Coast. 

University of California Press, Los Angeles, California. 

W) Kozloff, E.N. 1974. Keys to the Marine Invertebrates of Puget Sound, the San Juan Archipelago, and 

Adjacent Regions. University of Washington Press, Seattle, Washington. 

X) Calcofi Atlas. No.19. California Cooperative Oceanic Fisheries Investigations, State of California Marine 

Research Committee. Pp. 179-185. 

Y) Brodskii, K.A. 1967. Calanoida of the Far Eastern Seas and Polar Basin of the U.S.S.R. Jerusalem Series, 

Keys to the Fauna of the U.S.S.R. Zoological Inst., Academy Sciences, U.S.S.R. No. 35. 

Z) Chapman, P.M., et a1. 1982. Relative Tolerances of Selected Aquatic Oligochaetes to Individual Pollutants 

and Environmental Factors. Aquatic Toxicology 2: 47-67. 

AA) Venkataramiak, A., et al. 1982. Studies on Toxicity of OTEC Plant Components on Eucalanus sp. from the 

Gulf of Mexico. Ocean Science and Engineering. 

BB) Zingmank, R.G. (ed.). 1978. An Annotated Checklist of the Biota of the Coasta1 Zone of South Carolina. 

University of South Carolina Press. 

CC) Thatcher, T.O 1978. The Relative Sensitivity of Pacific Northwest Fishes and Invertabrates to Chlorinated 

Sea Water. In: R.L. Jolley, et al. (eds.), Water Chlorination: Environmenta1 Impact and Health Effects. Vol. 

2. Ann Arbor Science Publishers, Ann Arbor, Michigan. p. 341. 

DD) Young, J.S., et al. 1979. Effects of Copper on the Sabelled Polychaete, Eudistylia vancouveri: I. 

Concentration Limits for Copper Accumulation. Arch. Environ. Contam. Toxicol. 8: 97-106. 

52 
Appendix 2. Example Calculation of Final Acute Value, Computer 

Program, and Printouts 

A. Example Calculation 

N = total number of MAVs in data set = 8 

Rank MAV ln(MAV) ln(MAV)2 P = R / (N+1) P

4 6.4 1.8563 3.4458 0.44444 0.66667 

3 6.2 1.8245 3.3290 0.33333 0.57735 

2 4.8 1.5686 2.4606 0.22222 0.47140 

1 0.4 -0.9163 0.8396 0.11111 0.33333 

Sum 4.3331 10.0750 1.11110 2.04875 

S2

 = 

4/)04875.2(11110.1

4/)3331.4(0750.10

2

2

−

− = 87.134 

S = 9.3346 

L = [ 4.3331 – (9.3346)(2.04875)] / 4 = -3.6978 

A = (9.3346) ( 0 ) – 3.6978 = -1.6105 05.

FAV = e-1.6105 = 0.1998 

B. Example Computer Program in BASIC Language for Calculating the FAV 

10 REM This program calculates the FAV when there are less than 

20 REM 59 MAVs in the data set 

30 X = 0 

40 X2 = 0 

50 Y = 0 

60 Y2 = 0 

70 PRINT "How many MAVs are in the data set?" 

80 INPUT N 

90 PRINT "What are the four lowest MAVs?" 

100 FOR R = 1 TO 4 

110 INPUT V 

53 
54 

120 X = X + LOG(V) 

130 X2 = X2 + (LOG(V)) * (LOG(V)) 

140 P = R / (N + 1) 

150 Y2 = Y2 + P 

160 Y = Y + SQR((X2 – X * X / 4)) 

170 NEXT R 

180 S = SQR((X2 – X * X / 4) / (Y2 – Y * Y / 4)) 

190 L = (X – S * Y) / 4 

200 A = S * SQR(0.05) + L 

210 F = EXP(A) 

220 PRINT "FAV = " F 

230 END 

C. Example Printouts from Program 

How many MAVs are in the data set? 

? 8 

What are the four lowest MAVs? 

? 6.4 

? 6.2 

? 4.8 

? .4 

FAV = 0.1998 

How many MAVs are in the data set? 

? 16 

What are the four lowest MAVs? 

? 6.4 

? 6.2 

? 4.8 

? .4 

FAV = 0.4365