EPA RESPONSE

TO PUBLIC COMMENTS

on the

DRAFT AQUATIC LIFE

AMBIENT WATER QUALITY CRITERIA

CADMIUM - 2015

March 2016

Office of Water

U.S. Environmental Protection Agency

Washington, DC
ii

TABLE OF CONTENTS

INTRODUCTION ........................................................................................................................................1

TOPIC 1: Comments regarding acute criteria duration change from 24 hours to one hour .........................2

TOPIC 2: Comments regarding H. azteca test by Ingersoll is not acceptable; retest should be done or test 

should be removed from criteria development............................................................................4

TOPIC 3: Comments regarding dissolved vs total concentration use...........................................................7

TOPIC 4: Comments regarding data quality, use, and availability...............................................................9

TOPIC 5: Comments regarding ESA considerations..................................................................................16

TOPIC 6: Other comments .........................................................................................................................22
1

INTRODUCTION

EPA’s Office of Water is charged with protecting ecological integrity and human health from 

adverse anthropogenic, water-mediated effects, under the purview of the Clean Water Act 

(CWA) Section 304(a)(l). The Agency has been working to update water quality criteria to 

protect aquatic life and aquatic-dependent wildlife from the presence of cadmium in freshwater 

and estuarine/marine environments in order to reflect the latest scientific knowledge.

EPA’s Ambient Water Quality Criteria (AWQC) document for cadmium presents draft acute and 

chronic criteria expressed as concentrations of cadmium in fresh and estuarine/marine waters 

(dissolved). The 2016 cadmium criteria document is an update to the 2001 cadmium criteria. The 

2016 update incorporates additional toxicological data for cadmium, while using the same 

criteria derivation process that was used in 2001. 

EPA submitted its Draft AWQC for Cadmium – 2015 for public comment on December 1, 2015. 

The request for scientific views on the draft was open for 90 days, and as of February 1, 2016 ten 

comment letters were received (note: one entry was repeated). EPA considered scientific views 

from the public on this draft document as well as any new data or information received. This 

report documents EPA’s response to the public comments provided.

The following tables divide the comments into common topics for ease of the reader (e.g., 

criteria duration, Hyalella azteca data, etc.). Comments are summarized and EPA’s responses to 

the summarized public comments are provided. EPA revised the 2015 draft considering these 

comments, and noted in the table where the document was edited, when applicable. Additional 

information about the public comments can be accessed at the official public docket that EPA 

has established for this action: Docket ID No. EPA-HQ-OW-2015-0753, accessible at 

www.regulations.gov.
2

TOPIC 1: Comments regarding acute criteria duration change from 24 hours to one hour

Comment

Number

(Organization)

Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0012

(Utility Water Act 

Group)

UWAG has concerns with EPA’s proposal to change 

the acute freshwater and estuarine/marine criteria 

averaging duration from 24 hours to 1 hour. The 

change is not adequately justified and is not supported 

by new studies in the Draft. The current 24-hour 

duration should be retained unless a strong scientific 

justification is presented.

Every previous iteration of the cadmium criteria has 

endorsed a 24-hour duration for the acute criteria. 

EPA appears to be making a policy decision that the 

acute criteria should be 1 hour, but does not present 

the associated science to support the revision which is 

inconsistent with CWA § 304(a)(1), which mandates 

EPA establish “criteria for water quality accurately 

reflecting the latest scientific knowledge.”

EPA compares the acute toxicity to ammonia but fails 

to provide information that compares the timedependent toxicity of cadmium with ammonia. 

Furthermore, assessing the toxicity of cadmium 

during the first 24 hours of an acute test is 

problematic because the vast majority of published 

studies reporting the acute toxicity of cadmium do not 

report patterns of lethality during the first 24 hours.

Several acceptable selected studies (Besser et al. 

2007; Buhl 1997; Diamond et al. 1997; Mebane et al. 

2012; Nebeker 1986) do not report 24-hour LC50s 

and the one study with relevant data (Duncan and 

Klavercamp 1983) had a 12-hour LC50 that was five 

times greater than the 96-hour LC50 (5.35 vs. 1.11 

μg/L, respectively). This value would be expected to be 

similar if cadmium was a fast-acting pollutant.

An earlier EPA publication (Speed of Action of 

Metals Acute Toxicity to Aquatic Life; EPA-822-R95-002) also justifies the 24-hour averaging period. 

The statement that “every previous iteration of the cadmium 

criteria has endorsed a 24-hour duration for the acute criteria” is 

inaccurate. Only the 2001 final cadmium criteria document used an 

averaging period of 24 hours, all prior cadmium criteria revisions 

(1996, 1985, and 1980) and the draft version of the 2001 revision 

used a one-hour averaging period. Further, with the exception of 

the criteria derived for freshwater copper, all other acute criteria 

for aquatic life use an averaging period of one hour.

The 1985 Guidelines provides the basis for the 1-hour duration. 

The criteria document states that “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.”

The 1985 Guidelines additionally state that “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.” Accordingly, the 

one hour averaging period is designed to be conservative and 

protective based on the potential for latent effects. 

A detailed discussion of the rationale for selecting the one hour 

averaging period was presented in Section 5.1.4 of the 2015 draft 

criteria revision, and is included in the final 2016 criteria 

document. As noted in this section, the 24-hour duration used in 

the 2001 final cadmium criteria document was based on a limited 

number of fish toxicity studies and did not address trends in 

duration for a broader range of fish species or for other species

groups, including aquatic invertebrates. 

No edits
3

Comment

Number

(Organization)

Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

This document estimated a kinetic coefficient (k) using 

a regression of LC50 values versus time, with the 

averaging period being calculated as the inverse of k. 

The larger the k value the faster acting the pollutant. 

None of the estimated averaging periods in the 

document for freshwater and saltwater species 

approached 1-hour. The highest estimated k values 

mentioned, for the freshwater fathead minnow, were 6 

and 17 hours, with saltwater species having even 

larger values. The selection of the 1-hour averaging 

period is baseless and arbitrary.

Additionally, the 1985 Guidelines say the duration 

should be “substantially less than 48 to 96 hours,” but 

do not say that 24 hours is an inappropriate duration 

and therefore the Guidelines do not support, nor 

should it be a justification for the proposed revision.

The EPA 1995 document (Speed of Action of Metals Acute 

Toxicity to Aquatic Life, EPA-822-R-95-002) that the commenter 

refers to is a compilation of a series of memos and data from a 

contractor to EPA. This 1995 document suggests the possibility of 

longer averaging periods. However, that 1995 document included 

tests for only a very few aquatic species, and very little data at 

observation periods of less than 24 hours was included. 

Additionally, in Summary Table 1 of this 1995 document, eight of 

the 11 tests for cadmium indicate an averaging period of less than 

24 hours; thus an averaging period of 24 hours would not be 

protective. Additionally, all of the species in the tests in the 1995 

document were relatively insensitive to cadmium, less acutely 

sensitive than 40 other genera, and falling above the 50th percentile 

in the sensitivity distribution presented in the 2016 criteria 

document. Thus we do not currently consider this 1995 publication

a strong premise upon which to revise the long-standing and

standard one-hour averaging period recommended in the 1985 

Guidelines, and followed in 44 of the 46 numeric Aquatic Life 

Criteria that have been published by EPA. Thus, based on the 

limited nature of the available data, the absence of additional 

supporting information for other species, and the potential for 

latent effects, EPA revised the acute duration in the 2015 draft 

documents to the one-hour duration to be consistent with 1985 

Guidelines recommendations and the more protective one hour 

averaging period used for almost all other criteria. The one-hour 

duration for the acute criteria is retained in the 2016 final cadmium 

Aquatic Life Criteria.

EPA-HQ-OW2015-0753-0012

(Utility Water Act 

Group)

Water Quality-Based Effluent Limits (WQBELs) for 

cadmium are often expressed as a daily (24-hr) 

maximum value. Changing the WQBEL to a 1-hour 

averaging duration could require a permittee to 

collect several compliance samples during a 24-hour 

period. This additional burden is unnecessary since

there is minor variability of the cadmium levels during 

a typical 24-hour period, and this additional 

monitoring is unwarranted without sound scientific 

basis.

Please see response to above comment. While the criterion 

duration will now be expressed as one hour, WQBELs will

continue to be expressed in terms of Maximum Daily and Average 

Monthly averaging periods. This is consistent with NPDES 

regulations at 40 CFR 122.45(d) and with WQBEL derivation 

procedures in EPA’s TSD, as it has been applied to other 

chemicals that have acute aquatic life criteria expressed with a onehour duration component. Changing the duration to one hour 

would therefore not have an effect on the expression of WQBELs

or necessitate that additional samples be collected.

No edits
4

TOPIC 2: Comments regarding H. azteca test by Ingersoll is not acceptable; retest should be done or test should be 

removed from criteria development

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0007

and EPA HQ-OW2015-0753-0008

(Illinois 

Environmental 

Protection 

Agency)

The proposed chronic criterion is based on a flawed 

toxicity test (Ingersoll and Kemble 2001) conducted 

on the amphipod Hyalella azteca. The Hyalella test 

used in the criterion derivation should be repeated 

using current feeding procedures that are proven to 

result in better growth and reproduction. While the 

IEPA acknowledges and commends the improvements 

USEPA has made in the assessment and analysis of 

Hyalella sp. data compared to the 2001 cadmium 

criteria document, specifically in regards to the 

sensitivity of this organism to the presence/absence of 

chloride and bromide in culture and test water, the 

IEPA contends that the feeding regime employed in 

the 2000 USGS study is deficient by today’s standards 

and likely resulted in malnourished, stressed test 

organisms.

Specifically, test organisms in the 2000 USGS study 

were underfed and/or fed improper diets based on

current research. Dr. Soucek, at the Illinois Natural 

History Survey, conducted new research that focused 

on determining the appropriate amounts of food for 

test organisms. His research has led to improved 

growth of test organisms compared to earlier diet 

regimes. The diet used in the 2000 USGS study 

consisted of a ration of 1.0 ml YCT/d, whereas Dr. 

Soucek’s research contends that a diet consisting of 

Tetramin supplemented with diatoms greatly improves 

growth and reproduction of Hyalella azteca compared 

to YCT-only diets (Soucek et al. 2016, in press).

The diet in the 2000 USGS study restricted growth 

and fecundity when compared to Tetramin-based diets 

(Soucek et al. 2016, in press), and brings into question 

the accuracy of the test results.

While the results of the investigation by Soucek et al. (in press) 

suggest increased H. azteca growth and reproduction when diets of 

Tetramin are supplemented with diatoms or wheatgrass, compared 

to YCT, these results do not indicate a different level of H. azteca

sensitivity to chemicals. Moreover, growth and reproduction for 

the Ingersoll and Kemble (2001) investigation are within the 

acceptable range based on current applicable guidelines. Average 

control growth (0.524 mg dw/individual after 42 days, as indicated 

by the regression equation) is acceptable based on applicable 

guidelines presented in ASTM (2005) (> 0.15 mg dw/individual) 

and Environment Canada (2013) (> 0.10 mg dw/individual), and as 

recommended by Mount and Hockett (Appendix K) (> 0.50 mg 

dw/individual). Similarly, average control reproduction (6.4 

young/female after 42 days) is acceptable based on applicable 

guidelines presented in ASTM (2005) (> 2 young/female) and as 

recommended by Mount and Hockett (Appendix K) (> 6 

young/female). The test by Ingersoll and Kemble (2001) is 

therefore considered to be acceptable for use in deriving the 

chronic criterion. Further, EPA’s use of the Ingersoll and Kemble 

(2001) data reflects external peer reviewer recommendations that 

this specific study be used, as it represents the best available data 

for estimating cadmium toxicity to H. azteca.

No edits

EPA-HQ-OW2015-0753-0007

and EPA HQ-OW2015-0753-0008

Test organisms in the 2000 USGS study did not attain 

minimum growth requirements based on the direct 

measure of organism weight, with the average dry 

weight of the controls being 0.27 mg/individual 

EPA communicated directly with the author of the 2000 USGS 

study, who indicated direct measures of weight were unreliable at 

the time the study was conducted, primarily due to the small 

weights of the organisms being measured. In contrast, length

No edits
5

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

(Illinois 

Environmental 

Protection 

Agency)

(<0.50 mg/individual). USEPA concluded that the dry 

weights measured in the test were inaccurate and 

subsequently used length data to extrapolate to dry 

weight via a regression equation. However there is no 

documentation provided for this equation or how it 

was derived. It is unlikely that the dry weights were 

underestimated (while an overestimation can be 

expected due to inadequate drying of test organisms), 

and it is therefore considered unlikely that the 

organisms achieved the minimum weight requirements 

for this test to be valid.

measures had long been used by the lab and were determined to be

accurate and reliable by the author at the time the study was 

conducted. The equation used to determine weight from length, 

and which was established by the same lab, has been used in 

multiple peer-reviewed publications (examples provided in 

Appendix A) and will be included in the forthcoming ASTM 

guidance for conducting tests with H. azteca.

Provided below is a list of representative peer-reviewed 

publications using H. azteca length-to-weight regression in toxicity 

test results, indicating both the utility and acceptability of this 

approach.

Besser JM, Brumbaugh WG, Ingersoll CG, Ivey CD, Kunz JL, 

Kemble NE, Schlekat CE, Garman ER. 2013. Chronic toxicity of 

nickel‐spiked freshwater sediments: Variation in toxicity among 

eight invertebrate taxa and eight sediments. Environ. Toxicol.

Chem. 32:2495-2506.

Besser JM, Ingersoll CG, Brumbaugh WG, Kemble NE, May TW, 

Wang N, MacDonald DD, Roberts AD. 2015. Toxicity of 

sediments from lead-zinc mining areas to juvenile freshwater 

mussels (Lampsilis siliquoidea), compared to standard test 

organisms. Environ. Toxicol. Chem. 34:626-639.

Besser JM, Ivey CD, Brumbaugh WG, Ingersoll CG. 2015. Effect 

of Diet Quality on Chronic Toxicity of Aqueous Lead to the 

Amphipod, Hyalella azteca. Environ. Toxicol. Chem. (in 

press) doi:10.1002/etc.3341

Ivey CD, Ingersoll CG. 2016. Influence of bromide on the 

performance of the amphipod Hyalella azteca in reconstituted 

waters. Environ. Toxicol. Chem. (in press) doi: 10.1002/etc.3421

Kemble NE, Hardesty DK, Ingersoll CG, Kunz JL, Sibley PK, 

Calhoun DL, Gilliom RJ, Kuivila KM, Nowell LH, Moran PW. 

2013. Contaminants in stream sediments from seven U.S. 

metropolitan areas: II. Sediment toxicity to the amphipod Hyalella 

azteca and the midge Chironomus dilutus. Arch. Environ. Contam.

Toxicol. 64:52-64.
6

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-

0007andEPA HQOW-2015-0753-

0008 (Illinois 

Environmental 

Protection 

Agency)

The dilution series (control and 5 treatment 

concentrations: 0.1, 0.3, 0.5, 2.0 and 3.0 μg/L.) used 

in the 2000 USGS test did not appropriately bracket 

the effect concentration. The dilution series was not 

standard, with a large gap in concentration between 

the NOEC and LOEC (0.5 and 2.0 μg/L, respectively). 

While a point estimation technique was used to 

determine the effect concentration, the lack of a 1.0 

μg/L treatment may have changed this estimation. The 

precision of this estimation is paramount, as the test 

result was the sole determinant of the GMCV, which is 

the most sensitive in the chronic dataset, and a small 

change in the GMCV can therefore have a substantial 

effect on the final chronic value.

When graphed with a response curve, the data indicate a break in 

the curve close to the 1.9 ppb treatment concentration. Dr. Mount 

and Dr. Hockett (EPA Duluth Lab) conducted a sensitivity analysis 

and determined that, because the curve breaks close to 1.9 ppb, the 

spacing of treatments between 0.51 ppb and 1.9 ppb would not 

have an appreciable effect on the calculated EC20.

No edits

EPA-HQ-OW2015-0753-0007

and EPA HQ-OW2015-0753-0008

(Illinois 

Environmental 

Protection 

Agency)

At this time, the IEPA is in support of the adoption of 

the acute cadmium criterion as proposed, but is 

requesting a one year extension for the adoption of the 

chronic criterion. A one year extension would allow 

for a retest on Hyalella azteca using current feeding 

recommendations and would allow for revisions to be 

made to the chronic criterion. A round robin 

approach would ensure that the data are obtained 

using the appropriate test procedures and would 

provide additional information regarding the 

sensitivity of Hyalella azteca to cadmium. If time does 

not permit a repeat of the test, then the chronic 

criterion should be recalculated with the Hyalella 

data removed.

EPA found that survival, growth, and reproduction in the USGS 

2000 study is consistently acceptable based on current guidelines. 

Based on this and on the results of the additional detailed 

evaluation of the USGS study conducted by Dr. Mount and Dr. 

Hockett (EPA Duluth Lab) and Dr. Ingersoll (USGS), it was 

confirmed that the USGS study is acceptable for use in deriving 

the acute cadmium criterion. EPA has used the best available 

reliable data in the derivation of both the acute and chronic 

cadmium criteria.

No edits
7

TOPIC 3: Comments regarding dissolved vs total concentration use

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA HQ-OW2015-0753-0005

(Florida 

Department of 

Environmental 

Protection)

Additional documentation is needed to support the 

total to dissolved conversion factors. Very little 

information is provided concerning the derivation of 

the conversion factors, and more detailed information 

is needed to fully assess their appropriateness for 

natural waterbodies.

Information has been added to the document to better describe the 

use of derived total to dissolved conversion factors.

The acute freshwater conversion factors were determined 

empirically whereby total and dissolved cadmium concentrations 

were measured during 48- and 96-hour Daphnia magna and 

fathead minnow static toxicity tests conducted at different total 

hardness (TH) levels (Stephan 1996; University of Wisconsin –

Superior 1995). Either cadmium chloride or cadmium sulfate were 

spiked in Lake Superior water and measured at test initiation and 

completion. The time weighted averages (TWA) obtained for 

percent dissolved cadmium for each simulation were used to 

determine the freshwater acute conversion factors of 0.973 at 50 

mg/L TH, 0.944 at 100 mg/L TH and 0.915 at 200 mg/L TH. 

Freshwater chronic conversion factors obtained from the same tests 

and extrapolation procedures were 0.938, 0.909 and 0.880 at 50, 

100 and 200 mg/L TH, respectively. The lower chronic conversion 

factors are due to the longer TWA period employed relative to the 

acute factors. The acute saltwater conversion factor of 0.99 

determined by Lussier et al. (1999) was based on an Americamysis 

bahia 96-hr flow-through exposure and mean weighted total and 

dissolved cadmium concentrations. Narragansett Bay seawater was 

spiked with cadmium chloride and exposure concentrations were 

measured at 1- and 96-hrs. 

Section 2.6 

EPA HQ-OW2015-0753-0005

(Florida 

Department of 

Environmental 

Protection) 

It is unknown if the solutions prepared from Cd salts, 

that were used to develop the conversion factors, 

adequately represent the forms of Cd found in natural 

waterbodies.

Cadmium chloride and cadmium sulfate salts were used in the 

simulation tests, which are the same salts generally used in 

cadmium toxicity testing and typically found in the environment. 

Section 2.6 
8

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA HQ-OW2015-0753-0005

(Florida 

Department of 

Environmental 

Protection)

An explanation is needed as to why the conversion 

factors for the acute and chronic criteria are different. 

It also appears illogical that the constant conversion 

factor of 0.994 used for marine water is higher than 

for freshwater, especially because the hardnessdependent conversion factor for freshwater decreases 

as hardness increases.

Information has been added to explain the difference between the 

acute and chronic conversion factors. 

The acute and chronic freshwater conversion factors were obtained 

from the same acute toxicity tests, with the only difference 

between the tests being the longer time weighted average (TWA) 

procedure applied to derive the chronic conversion factors relative 

to the acute factors. 

The freshwater and saltwater conversion factors are each based on 

dissolved-to-total ratios determined with toxicity tests using 

natural surface water. The only difference between the two is that 

the freshwater conversion factors were extrapolated using TWA 

procedures, whereas the saltwater conversion factor was based on 

mean weighted total and dissolved cadmium concentrations

determined at test initiation and completion.

Section 2.6 

EPA HQ-OW2015-0753-0005

(Florida 

Department of 

Environmental 

Protection)

While it is noted in several places in the document, 

clarify that the recommended criteria values are 

expressed as dissolved cadmium concentrations (not 

total). Also clarify if states have the option to adopt 

total Cd criteria values.

EPA provides both dissolved and total concentrations for use by 

states and is maintaining both of these values in the final cadmium 

criteria document. However, EPA recommends the use of 

dissolved concentration, whenever possible, as it better represents

the bioavailable fraction of cadmium in water.

No edits

EPA HQ-OW2015-0753-0011

Kansas has utilized the total recoverable metals 

criteria and data, and is not set up to sample for total 

dissolved metals. A conversion factor would be 

applied to calculate the dissolved concentration and 

Kansas recommends that EPA retain this flexibility in 

its final criteria.

Please see response to previous comment.

No edits
9

TOPIC 4: Comments regarding data quality, use, and availability

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0006

(Kansas 

Department of 

Health and 

Environment)

Some of the values that are new/revised since the 2001 

AWQC document are from studies that were published 

before 2001. Table 22 has general information 

describing why GMAVs have changed between the 

2001 and 2015 document, but it does not provide 

details on why these "new" data were now considered

acceptable. Include another table that describes why 

the studies that were excluded previously are now 

included.

The “new” acceptable data published prior to 2001 were never 

reviewed during the 2001 document update because the 

papers/reports were not available at that time. Acquisition of 

papers/reports during the 1999/2000 time frame was more difficult 

than currently available procedures, especially with present day 

enhanced internet capabilities. In some cases, data considered 

acceptable back in 2001 were deemed unacceptable during this 

update because more stringent acceptability criteria were 

implemented by EPA.

No edits

EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey)

Should toxicity tests conducted under less-than 

optimal conditions be discounted? This comment goes 

beyond just the test results for Hyalella, because while 

laboratory tests used for criteria development use 

conditions that are as close to optimal as possible, 

wild populations in diverse natural conditions are 

often exposed to conditions that sub-optimal, and 

therefore laboratory tests may be underprotective in 

natural conditions (i.e., additional stresses) (see, 

Holmstrump et al. 2010; Besser et al. 2015). 

The acceptability of test results for inclusion in criteria 

development is currently based on the standards of acceptability 

established in the 1985 Guidelines and applicable testing protocols 

(e.g., ASTM).The list of studies considered acceptable for 

qualitative but not quantitative use in criteria derivation (“Other 

Data”) are provided in Appendix H and I of the 2016 cadmium 

criteria document for freshwater and estuarine/marine tests, 

respectively. Tests that were not included in the quantitative 

evaluation were discussed, as appropriate, as part of the Effects 

Characterization (Section 5). The list of studies considered 

unacceptable for use in criteria development and the reason why 

they were not used are provided in Appendix J of the 2016 

cadmium criteria document. EPA concurs there is a range of 

natural variables that will affect organism condition in the 

environment. However, the test acceptability methodology 

employed for the selection of studies used in criteria derivation 

ensures acceptable test quality and reduces the potential that test 

outcomes are affected by artifacts.

No edits

EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey)

“Other data” are not addressed consistent with the 

Guidelines. While these data are not used in the 

species sensitivity distribution rankings, they should 

not be thrown away, discounted, or deemed 

“unacceptable.” “Other Data” can be invoked to 

lower a criterion (e.g., chronic value in the 1987 

selenium criterion). Revaluate Riddel et al. (2005a, b) 

and include a larger discussion of their effect 

concentrations/findings and other similar 

behavioral/ecological studies.

These “Other data” are used qualitatively to support toxicity data 

compiled for existing species to derive the criteria. While some of 

these data may be used in characterization, data deemed 

unacceptable are not used in criteria derivation.

The artificial stream study data from Riddel et al. (2005a, b) and 

Mebane et al. (2014) describing cadmium effect concentrations on 

behavior and predator-prey interactions have been added to Section

5.2 of the document.

Sections 5 and 5.2
10

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey)

With many organisms, a strong difference in the 

sensitivity of different life stages makes it 

inappropriate to roll up data from different 

developmental stages. Pooling salmonid effects 

concentrations across developmental stages to obtain 

a SMAV could produce a misleading result (see, 

Hansen et al. 2002; Mebane et al. 2012; Chapman 

1978; Chapman and Stevens 1978).

When a clear difference in the sensitivity of species is apparent 

across life stages then only the data for the most sensitive life stage 

is used to calculate the SMAV. The data in Appendix A and B 

were re-evaluated and the SMAV for rainbow trout and Chinook 

salmon were re-calculated using only the most sensitive life stages

(i.e., smolts were not used in the SMAV calculation).

Appendix A

Ranked FW Acute 

Table

EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey)

The decision to only use ELS chronic data in which 

the exposures began in the egg stage, and to exclude 

long-term data in which the exposures began in the fry 

stage is non-conservative.

This decision was based on previous external peer review 

comments. The use of the life cycle (LC) tests over the early life 

stage (ELS) tests in the draft reviewed by the external peer 

reviewers was consistent with the 1985 Guidelines. It was noted by 

the reviewer that for salmonids there was no consistent pattern of 

early life stage tests being more sensitive than life cycle tests.

Based upon the peer reviewer comment, use of sensitive salmonid 

tests was reconsidered and changes in the approach were made for 

the 2015 draft criteria. Specifically, ELS tests were used to 

calculate the revised SMCV in instances where they were more 

sensitive than the LC tests (e.g., Salmo trutta). Therefore the most 

conservative test type was chosen for each species.

No edits

EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey)

SMAV calculations tagged with the footnote “C”,

indicating that “Data not used to calculate SMAV 

because more sensitive life stage available, or flowthrough measured test available”, should be 

separated into two different footnotes since they are 

very different reasons.

A footnote has been added to separate out “Data not used to 

calculate SMAV because more sensitive life stage available” from

“flow-through measured test available”. Appendix A and 

Appendix B

EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey) 

Address the following Appendix A specific 

errors/changes:

 Daphnia magna (various)

o Many “S, U” tests (tests with 

unmeasured concentrations) are 

underlined, indicating they are included 

in the SMAV calculations. These should 

be excluded per the Guidelines.

 Per the 1985 Guidelines (Section IV. I), acceptable 

static/unmeasured acute tests are only excluded from SMAV 

calculations when there is an acceptable flowthrough/measured test available for the species. In addition, 

only for certain volatile or easily degraded contaminants 

(which cadmium is not) would static/unmeasured tests be 

considered for exclusion. Thus, if an acceptable flowthrough/measured test is not available for Daphnia magna, 

then all acceptable acute data are used to calculate the SMAV 

for this species.

Appendix A

Ranked FW Acute 

Table

 Mayfly (formerly, Ephemerella grandis) Drunella 

grandis

o Tested species was listed in the source 

 Warnick and Bell (1969) did indeed conduct toxicity studies 

with Ephemerella subvaria, but Clubb et al. (1975) conducted 

tests with Ephemerella grandis (now classified as Drunella 
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document as Ephemerella subvaria, 

which is still a valid species name 

according to ITIS.gov.

grandis grandis). These two tests were broken out in 

Appendix A, with the corrected name changes cited where 

appropriate.

 Rainbow trout (smolt), Chapman 1975 (>2.9 

μg/L)

o Should be excluded from SMAV because 

it is from a resistant life stage. Also, 

should be listed as “Rainbow trout 

(Steelhead smolt)” as Steelhead are not 

just Rainbow Trout by a different name, 

but have physiological differences in 

regard to ion regulation. Chapman 

(1975) should only be cited when no 

alternative exists, because it was never 

formally released by EPA and is not 

publicly available online. Chapman 

(1978) reports the same data and is a 

better citation.

 Rainbow trout (smolt), Chapman 1975 (4.1 μg/L)

o Suspect value, exclude from SMAV. 

Chapman (1978) lists the value for the 

same test as >2.9 μg/L. Chapman (1978) 

is the peer-reviewed publication of 

record for these data; Chapman (1975) 

was an unpublished, work-in-progress 

progress report that sometimes still gets 

cited because it includes data never 

published elsewhere, such as the coho 

data shown in the figure in this memo. 

Exclude from SMAV, resistant life stage 

and re-label as ““Rainbow trout 

(Steelhead smolt”. See Chapman (1978, 

Table 3).

 The Chapman (1975) unpublished report data were deleted 

from the appropriate tables, based on indication by the author 

that the published paper (i.e., Chapman 1978) superseded the 

report. Further, the value for the smolt was removed from the 

calculation of the SMAV for rainbow trout because it is a 

more resistant life stage. Studies were grouped by scientific 

name for evaluation, and were not differentiated based on 

functional characteristic.

 Rainbow trout (299 mg), Stratus (1.29 μg/L)

o Exclude from SMAV; pH was 

manipulated (lowered to 6.5) and 

matched tests with unmanipulated pH of 

7.5 were much more sensitive

 The pH manipulated value from Stratus Consulting (1999) for 

the rainbow trout is appropriate to use since it is within the pH 

range for permitted outfalls (6.5-9.0) and is within the range of 

pH found in ambient surface waters. Thus the test conducted 

at pH 6.5 reflects the natural environment and should be 

included in the database.

 Chinook salmon (parr, 11.58g) (3.5 μg/L)

o Exclude value from SMAV, based on a 

resistant life stage being tested. Value is 

 The Chinook salmon values for the parr and the smolt were 

removed from the SMAV calculation because they are from a 

more resistant life stage.
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twice as high as the value obtained with 

swim-up fry in matched tests and 

confidence limits don’t overlap.

 Chinook salmon (smolt, 32.46 g) (>2.9 μg/L)

o Should be excluded from SMAV, based 

on a resistant life stage being tested.

 Bull trout (84.2 mg) (2.89 μg/L)

o Exclude from SMAV; pH was 

manipulated (lowered to 6.5) and 

matched tests with a natural pH of 7.5 

were much more sensitive

 The pH manipulated value from Stratus Consulting (1999) for 

the bull trout is appropriate to use since it is within the pH 

range for permitted outfalls (6.5-9.0) and is within the range of 

pH found in ambient surface waters. Thus the test conducted 

at pH 6.5 reflects the natural environment and should be 

included in the database.

 Colorado squawfish

o Old common name is now considered 

repugnant. AFS calls it “Colorado 

pikeminnow”. “Pikeminnow” is one 

word.

 The Colorado squawfish common name was changed to 

Colorado pikeminnow.

EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey)

Address the following Appendix C specific 

errors/changes:

 Snail, Aplexa hyporum (Holcombe) (4.0 μg/L)

o I got an EC20 of about 2.6 μg/L. By 

excluding the highest treatment with 

total mortality I could reproduce the 4.0 

EC20 value, but it had a poor fit with Y0.

Two separate EC20s for Holcombe et al. (1984) were calculated: 1) 

an un-normalized EC20 of 4.002 μg/L based on the number of egg 

masses per snail for tanks A and B, and 2) an un-normalized EC20

of 0.8737 μg/L based on survivors to test end for tanks C and D. 

The EC20 of 4.002 μg/L was calculated using the threshold sigmoid

model in TRAP version 1.21 (and was replicated in TRAP version 

1.30 with the same result) using the following initial parameters: 

log X50 = 0.7, S=2, y-intercept=90. 

No treatments were excluded (treatments with 100% mortality 

were treated as having 0 egg masses/snail). 

If test data from tanks A and B are combined with data from tanks 

C and D, the un-normalized EC20 for egg-masses per snail was 

calculated as 2.515 μg/L, using a threshold sigmoid model in 

TRAP version 1.30. This was the only method where EPA was 

able to calculate an EC20 similar to 2.6 μg/L.

The present method of calculation (two EC20s of 4.002 and 0.8737 

μg/L, respectively) results in a similar (un-normalized geometric 

EC20 of 1.870 μg/L), but slightly more conservative value for 

Aplexa than the un-normalized 2.515 μg/L that would be obtained

for the number of egg masses per snail by combining data from 

tanks A-D.

No edits
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EPA-HQ-OW2015-0753-0013

(Chris Mebane, 

US Geological 

Survey)

Add the following additional relevant data:

 Pascoe and Mattey 1977

o Chronic stickleback exposure

 Wang et al. 2014

o Chronic fathead full life-cycle test

 Brinkman and Vieira 2008

o Acute and chronic mountain whitefish

 Mebane et al. 2014 (paper provided)

o Effects of cadmium on larval aquatic 

insect communities in 30-day 

experimental stream tests

 Pascoe and Mattey 1977

o Study was deemed unusable because of: 1) no control 

information and 2) dilution water was not defined 

(appears to be reconstituted water).

 Wang et al. 2014

o Study was deemed unusable because of: 1) only three 

exposure concentrations, 2) a static chronic exposure

(should be static-renewal or flow-through) and 3) 

only a 21-day fish test (should be at least 28 days).

 Brinkman and Vieira 2008

o Consistent with 1985 Guidelines, the study was 

deemed unusable because scientific name was not 

given (only common name given).

o Further, elevated cadmium concentrations were 

measured in controls.

o Additionally, for the Early Life Stage tests, 

temperature measurement did not follow ATSM 

guidance. 

 Mebane et al. 2014

o Initial review of preliminary summary shows 32-day 

effects levels at 0.1-0.8 μg/L Cd. However the natural 

river water used for dilution is only partially 

characterized.

Mebane et al. (2014) 

added to Section 5.2
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EPA-HQ-OW2015-0753-0014

(Center for 

Biological 

Diversity)

There is concern about the focus on fish in developing 

the criteria. EPA needs to bring in other species 

including insects and freshwater mussels into the 

process when developing criteria for cadmium. This 

lack of additional species prevents a more holistic 

picture of the freshwater community, and results in 

criteria that are not protective of all aquaticdependent wildlife. EPA has consistently failed to fully 

consider aquatic-dependent wildlife in the 

development of national criteria.

The 1985 Guidelines requires acceptable data to be available for at 

least eight genera with a specified taxonomic diversity, which is

the standard eight-family minimum data requirement (MDR). The 

purpose of the eight-family MDR is to serve as a surrogate sample 

community representative of the larger and typically much more 

diverse natural aquatic community, which includes aquatic 

invertebrates and extends well beyond the protection of fish. In 

fact, five of the 8 MDRs are for invertebrates, not fish. Data were 

available to meet these MDRs for freshwater acute and chronic 

criteria and for the estuarine/marine acute criterion. Table 5 was 

revised in the final criteria document to more clearly summarize

species included as part of the MDRs. 

As discussed in Section 2.3 of the criteria document, mammals and 

avian wildlife could be exposed to cadmium in abiotic media while 

foraging in aquatic habitats or via the ingestion of prey that have 

bioaccumulated cadmium from the aquatic environment. However, 

freshwater biota are considered to be the most sensitive to 

cadmium. Marine organisms are generally considered to be more 

resistant than freshwater organisms, while mammals and birds are 

considered to be comparatively resistant to cadmium (Burger 2007; 

Eisler 1985). Based on these observations, criteria that are 

protective of aquatic life are also considered to be protective of 

mammalian and avian wildlife (including aquatic-dependent 

wildlife) and aquatic life were therefore the focus of the 

evaluation.

No edits

EPA-HQ-OW2015-0753-0010

(Hampton Roads 

Sanitation 

District)

There is concern with the continued lack of 

estuarine/marine chronic cadmium toxicity data and 

that no new chronic toxicity data have been generated 

since 2001. EPA should conduct additional chronic 

toxicity studies (particularly with vertebrate species) 

to expand the estuarine/marine chronic toxicity 

dataset. More estuarine/marine chronic data are 

needed to develop a scientifically reliable chronic 

cadmium criterion.

Chronic data on estuarine/marine species are extremely limited. 

For this reason, ACRs were derived using the robust acute 

estuarine/marine database and consistent with the 1985 Guidelines 

to support derivation of the estuarine/marine chronic value. EPA 

agrees that generation of additional estuarine/marine chronic 

toxicity data for cadmium by the scientific community would be 

desirable.

No edits
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EPA-HQ-OW2015-0753-0010

(Hampton Roads 

Sanitation 

District)

The mysid Neomysis integer is a new species added to 

the estuarine/marine acute dataset, but this mysid is 

potentially non-native to the United States. Since there 

are available values for two other native mysid 

species (M. bigelowi and A. bahia), this non-native 

species should be removed (unless documentation is 

provided confirming it is naturally occurring within 

waters of North America).

Neomysis integer has been removed from the database since it is 

not occurring within waters of North America. In addition, a new 

North American estuarine/marine species, Neomysis americana, 

has been added to the database after obtaining a new paper (i.e., 

Roberts et al. 1982), thus potential use of the non-native species as 

a surrogate for other mysids is unnecessary. 

Section 3.2.1 and 

Appendix B
16

TOPIC 5: Comments regarding ESA considerations

Comment 

Number

Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0014

(Center for 

Biological 

Diversity)

EPA must ensure that any criteria (“Action”) that it 

recommends to states for adoption will be fully 

protective of listed species. The federal act of 

establishing criteria has both direct and indirect 

effects for listed species. Therefore Section 7 

consultations would be beneficial since there are 

several areas where peer reviewers and the EPA 

disagree (i.e., bioaccumulation, data used in the 

hardness correction, and incorporation of the BLM). 

Involvement of biologists from the Services could 

benefit the resolution of these and other issues.

Furthermore, the language in the Endangered Species 

Act (“ESA”) states that EPA must consult the Services 

in its recommendations of the criteria.

EPA disagrees that before making general recommendations to 

states regarding future state actions to adopt cadmium criteria 

(“national recommendations”), it is helpful or legally necessary to 

first engage in consultation under the ESA to ensure that any 

possible subsequent federal action to approve new or revised state 

cadmium criteria consistent with the national recommendations 

would necessarily be protective of listed species. The issuance of 

national criteria recommendations for cadmium does not impose

any legally binding requirements on states. Nor does it authorize 

any state or federal action that would otherwise be inconsistent 

with the ESA, simply on the grounds that such action is consistent 

with EPA’s national recommendations under the Clean Water Act. 

Since the distribution of listed species which might affect the 

appropriate water quality criteria is location-specific, and the 

national recommendations for cadmium are intended to be 

generally informative, allowing the most sensitive location-specific 

potential concerns to drive national recommendations would tend 

to inappropriately distort those recommendations. 

EPA believes that national-level efforts to consult on potential 

future approvals of new and revised state cadmium criteria would 

be neither efficient, likely to ensure a consistent approach to 

evaluating the effects of pollutants on species, nor necessary to 

address the effects of action on species whose ranges cross state 

boundaries: (1) It would be inefficient because it would tend to 

produce national criteria recommendations for cadmium that states 

would need to modify to make less stringent before incorporating 

into their own standards, based on the absence of species-specific 

concerns. EPA believes that it is more efficient for states to 

modify national criteria recommendations for cadmium to make 

them more stringent, as needed based on the presence of localized 

species-specific concerns. (2) It is unlikely to ensure a consistent 

approach because the Services have indicated that national 

consultation on recommended cadmium criteria would not obviate 

the need for further consultation at the Service field office level, on 

subsequent federal actions to approve particular new or revised 

state water quality criteria for cadmium. Any gains in consistency 

from an initial national consultation are likely to be undone by 

inconsistencies among the follow-up consultations at the field 

office level. (3) National consultation is unnecessary to adequately 

No edits
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address concerns about trans-boundary movement of cadmium or 

organisms because when ESA consultation occurs on the proposed 

approval of a state’s new or revised cadmium criteria, there is no 

bar to considering pertinent effects on species outside the state’s 

jurisdiction. Such effects may be relevant for a number of reasons, 

including that EPA requires each state to take into consideration 

the water quality standards of downstream waters when setting its 

own criteria. 40 CFR 131.10(b).

Irrespective of these national 304(a) recommendations, EPA 

intends to consult with the Services about a proposed approval of 

a state water quality standard under Clean Water Act Section 

303(c), before undertaking the Federal action of approving, to the 

extent that it determines that such approval may affect listed 

species. 

EPA-HQ-OW2015-0753-0014

(Center for 

Biological 

Diversity) 

To ensure the final cadmium water quality criteria is

fully protective of all types of wildlife, EPA should 

engage the Fish and Wildlife Services (FWS) broadly

(not just as is legally required by the ESA) and 

include other divisions of the FWS that may have 

additional expertise and information that would be 

beneficial to the EPA.

Congress expected that EPA would engage with the 

FWS and other federal agencies when developing 

criteria. This engagement does not need to be 

burdensome or formalistic. The Fish and Wildlife 

Coordination Act (FWCA) can be used as a 

framework to achieve this coordination and 

strengthen the final recommended criteria.

EPA acknowledges that FWS strives to ensure that inter-agency 

consultation is neither burdensome nor formalistic. Nonetheless, 

for the reasons described above, consultation on these non-binding 

national 304(a) criteria recommendations is neither necessary nor 

helpful.

EPA disagrees with FWS’ suggestion that the FWCA would be a 

useful coordination framework for discussing national criteria 

recommendations under CWA § 304(a) and notes that the 

suggestion appears to be premised on a misunderstanding of the 

Clean Water Act. The FWCA relates to circumstances in which it 

is “proposed or authorized” that certain waters be “impounded, 

diverted, the channel deepened, or the stream or other body of 

water otherwise controlled or modified for any purpose.” 16 

U.S.C. § 662. In communicating national criteria 

recommendations to the public, EPA is neither proposing nor 

authorizing any modification of any water body.

No edits

EPA HQ-OW2015-0753-0009

(California State 

Water Resources 

Control Board)

The NMFS and FWS Final Biological Opinion for the 

State of Oregon’s adoption of the previous AWQC 

cadmium criteria (2001) and USEPA’s disapproval of 

the acute criterion required the State to develop 

replacement criteria based on:

1. Only using toxicity data for cadmium that 

was specific to salmonid fishes, and green 

sturgeon and eulachon, if available

2. Curve-fitting all toxicity data used to derive 

the numeric criterion

The NMFS and FWS (referred to here as the Services) Biological 

Opinions were developed for the state of Oregon’s Water Quality 

Standard, not the 2001 national 304(a) criteria, nor the draft 2016 

national 304(a) updated criteria, which are recommendations that 

were developed per EPA’s Guidelines for National Aquatic Life 

Criteria (Stephan et al, 1985). 

The commenter confuses the Reasonable and Prudent Alternatives 

expressed in NMFS’ biological opinion with the remedies stated in 

EPA’s Clean Water Act disapproval of the state water quality 

No edits
18

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Criteria Document

3. Extrapolating threshold acute and chronic 

toxic effect concentrations using the curvefitted data

4. Adjusting derived criteria to ac7count for 

chemical mixtures

5. Using a population model that integrates the 

derived criteria to predict no negative 

change in each species population’s intrinsic 

growth rate

These requirements were not applied to the new draft 

recommended criteria and the new acute value is 

greater than the previous recommendation. Since 

California shares similar ESA species populations to 

those in Oregon, the NMFS biological opinion must 

be considered. Furthermore, since the previous lower 

acute value resulted in a jeopardy decision, it is likely 

the new higher criteria will not be viewed favorably.

standard. Not one of the requirements listed by the commenter 

was actually imposed by EPA on the State of Oregon in its January 

30, 2013 disapproval of the Oregon acute criterion for cadmium.

The NMFS biological opinion found that exposure to cadmium at 

levels equivalent to the acute cadmium criterion values adopted by 

Oregon would jeopardize the continued existence of some of the 

endangered species under its jurisdiction and therefore the opinion 

included Reasonable and Prudent Alternatives (as summarized in 

the comment) to remedy the jeopardy decision. The final biological 

opinion from FWS did not find that the acute cadmium criterion 

would result in jeopardy of the listed species under its jurisdiction 

and did not contain the Reasonable and Prudent Alternatives 

summarized by the commenter. 

Because EPA is developing a federal rulemaking for Oregon to 

resolve EPA’s 2013 disapproval of Oregon’s acute cadmium 

criterion, EPA has conducted additional analyses, consistent with 

the Reasonable and Prudent Alternatives contained in the NMFS 

opinion, on the updated 2016 acute cadmium criterion magnitude 

relative to salmonid species of concern in Oregon. EPA notes that 

available salmonid “curve-fitted data” indicate that mean minimal 

salmonid effect levels specified by NMFS in the opinion occur at 

concentrations slightly higher than the national acute criterion 

recommendation or water quality standard based on this 

recommendation. EPA is conducting further analyses on potential 

mixture effects based on available data and results indicate 

protection from mixture combinations specified by NMFS at the 

cadmium acute criterion magnitude. EPA is also examining 

population modeling recommendations made in the NMFS 

Biological Opinion, in concert with the NMFS. 

Finally, EPA notes that additional protection is expected because 

the acute criterion duration is specified to be a one-hour duration, 

and the frequency recommendation is that the one-hour 

concentration not be exceeded more than once in 3 years on 

average. . The 2001 acute criterion for which the NMFS biological 

opinion was developed recommends a 24-hour duration. Therefore, 

the 2016 cadmium acute criterion duration provides an added level 

of protection for these species of concern, in addition to the 

protective magnitude through the use of a one-hour duration 
19

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Criteria Document

EPA HQ-OW2015-0753-0009

(California State 

Water Resources 

Control Board)

The new chronic criterion also presents a similar 

challenge, since it is higher than the criterion in the 

FWS and NMFS biological opinions. The 2015 draft 

recommended criteria are not sufficiently protective of 

ESA species in California.

Please see response to the above comments.

At such time as EPA reviews specific new or revised aquatic life 

water quality criteria for cadmium in California under Clean Water 

Act Section 303(c), EPA intends to consult with the Services about 

any proposed approval, to the extent that EPA determines that such 

approval may affect listed species. 

No edits

EPA HQ-OW2015-0753-0015

(National Marine 

Fisheries Service)

EPA needs to work with the NMFS to conduct a more 

thoughtful evaluation of the implications of their 

guidelines methodology for criteria development for

ESA listed species, especially in context of the limited 

data available for ESA-listed species. Comments on 

the prior ESA Section 7 Consultation with NMFS are 

included as attachments (multiple attachments). 

EPA's approach to addressing obligations under ESA 

(ESA consultation when agency approves stateproposed criteria) leads to a piecemeal approach, 

particularly for broadly-ranging species. Given the 

scope of the guidelines, the conclusions of such an 

assessment and any associated implementation 

guidance would need to have the same 

authority/regulatory implications of a Section 7 

Consultation.

Thank you for your comment. Please see response to comment 

EPA-HQ-OW-2015-0753-0014. No edits

EPA HQ-OW2015-0753-0015

(National Marine 

Fisheries Service)

’’EPA’s freshwater acute guideline is slightly above 

Oregon’s proposed criterion of 2.0 μg/L. It was 

determined that the proposed 2.0 μg/L criterion would 

jeopardize the continued existence of ESA-listed 

species occurring in that state. Several of the 96 hour 

LC50 values for the ESA-listed species used in the 

derivation of the Oregon standard are below the 

criterion, so these data were used to evaluate the 

implications on population growth rates. The analyses 

identified cases where population growth rates would 

be significantly altered based on exposure to 2.0 μg/L 

cadmium (see NMFS Attachment 4).

EPA’s chronic freshwater guideline for cadmium is 

also higher than the chronic criterion proposed by 

Oregon (0.73 μg/L vs 0.25 μg/L). NMFS analyses 

indicated exposure to 0.25 μg/L cadmium would result 

in sublethal effects, but the effects did not rise to the 

Please note the final 2016 acute freshwater criterion has been 

revised to 1.8 μg/L from 2.1 μg/L in the 2015 public review draft 

document based on minor changes to the salmonid dataset. 

Updated acute and chronic 304(a) national cadmium criteria 

recommendations are based on a robust dataset that included 101 

and 27 species, respectively. These data reflect the best available 

science, and include consideration of all available, quality tests on 

endangered species. As is true for all criteria, if data are available 

for endangered or other sensitive species that may be present in a 

state, state water quality standards can be developed to protect 

species present.

CWA Section 304(a) water quality criteria pertaining to the 

protection of aquatic life include three components, magnitude, 

frequency, and duration, which function together to provide 

protection to aquatic life. Duration components of the cadmium 

criteria reflect periods of time that are substantially shorter than the 

No edits
20

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Criteria Document

level of jeopardy. EPA’s 0.73μg/L guideline is nearly 

three-fold Oregon’s criterion and would be expected 

to result in more severe effects.

Idaho’s proposed (2006) acute and chronic 

freshwater criteria of 1.3 and 0.6 μg/L, respectively, 

and a NMFS analysis of these criteria determined they 

were not likely to adversely affect Idaho’s ESA-listed 

salmonids under NMFS jurisdiction (see NMFS 

Attachment 5). However, criteria applied elsewhere 

would still require an analysis incorporating locationspecific considerations.

lengths of toxicity tests used to derive criteria. Accordingly, 

duration components provide additional protection beyond the 

criteria magnitude. The frequency aspect of criteria provides 

additional protection, in that criteria magnitudes are recommended 

not to be exceeded more than once in 3 years on average. 

Regarding the chronic criterion, the cadmium chronic criterion 

duration is specified as 4 days, and is based on effects observed in 

chronic tests following exposures to cadmium that range from 

approximately 3 weeks to 6 weeks in duration. Thus, the cadmium

criterion chronic duration is expected to provide additional 

protection to aquatic species. The chronic criterion also cannot be 

exceeded more than once in 3 years on average. 

Population modeling to assess potential chronic effects should 

necessarily incorporate not just the magnitude, but the duration and 

frequency aspects of criteria in order to provide robust predictions 

of any projected population level effects.

EPA HQ-OW2015-0753-0015

(National Marine 

Fisheries Service) 

While the Oregon consultation concluded that ESAlisted sea turtles would be unlikely to accumulate a 

significant amount of cadmium from state waters, the 

draft cadmium guidelines apply to all waters of the 

US, so exposures would occur throughout the US 

portion of a sea turtle’s range. Cadmium accumulates 

in tissue with age and sea turtles are long lived 

species (20-50 years). For long lived species, it needs 

to be determined if cadmium accumulation from US 

waters over a lifespan would reach tissue 

concentrations resulting in or contributing to adverse 

effects. Dietary exposure of the more omnivorous sea 

turtle species (i.e., leatherback, loggerhead) are of 

particular concern. 

Data on estuarine/marine species, particularly chronic data, are 

extremely limited. Data on longer-lived species also remain a data 

gap for both EPA and other federal partners. As discussed in the 

criteria document, based on available data cadmium is unlikely to 

accumulate to levels that would result in adverse effects to aquatic 

invertebrates, fish, or wildlife from the ingestion of aquatic life that 

have accumulated cadmium in their tissues. No edits

EPA HQ-OW2015-0753-0015

(National Marine 

Fisheries Service)

There is a concern about the lack of data for the 

effects of cadmium on smalltooth sawfish and Atlantic, 

Gulf, or shortnose sturgeon species, and that ambient 

aquatic exposures alone would be inadequate to 

assess effects to ESA-listed species. These are longlived species (>20 years) that are known to ingest 

sediment (which may include particulate-bound 

cadmium originating from the water column) with 

their benthic prey.

EPA agrees that there is a lack of empirical data for listed species. 

As discussed in the criteria document, based on available data, 

cadmium is unlikely to accumulate to levels that would result in 

adverse effects to aquatic invertebrates, fish, or wildlife from the 

ingestion of aquatic life that have accumulated cadmium in their 

tissues. Most aquatic organisms are considered to be more 

susceptible to cadmium from direct aqueous exposure than through 

bioaccumulation and direct exposure effects are considered more 

applicable to the development of criteria protective of aquatic life.

No edits
21

Comment 

Number

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in 2016 Cadmium 

Criteria Document

EPA HQ-OW2015-0753-0015

(National Marine 

Fisheries Service)

While the limited data (see, Reichelt-Brushett and 

Harrison 2005; Mitchelmore et al. 2007; Howe et al. 

2014) suggest that the EPA guidelines for cadmium in 

marine waters are protective of coral species, the 

certainty of this conclusion is limited by the absence 

of data on colonization and recruitment, wound 

recovery, and predation activity.

There were no data available for coral species for EPA to consider. 

It is noteworthy that that criteria recommendations include 

components that increase the protection afforded aquatic species 

through limitations on exposure duration and frequency, in 

addition to magnitude (concentration) (see comment #: EPA HQOW-2015-0753-0015II). These aspects of criteria provide 

additional levels of protection to aquatic life, particularly if data 

suggest that the magnitudes of the updated cadmium criteria are 

protective.

No edits
22

TOPIC 6: Other comments

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0014

(Center for 

Biological 

Diversity)

In the description of sources of cadmium in the 

document, EPA overlooked the contribution from coal 

combustion, coal mining waste, and coal ash ponds 

spills, seepage, and discharge. These important 

sources need to be recognized and addressed.

Additional available information has been added to the document 

detailing the anthropogenic sources of cadmium from coal ash 

ponds/pits.

Section 2.1 

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

Check the document for errors and typos. Specific 

examples include:

 Pg.27 which is intended to provide an acute 

criterion protective of nearly all individuals in the 

distribution (Stephan et al. 1985);the FAV/2 

approach was developed to estimate minimal 

effect levels,

 Pg.30 This outcome was based on the poor 

correlation between hardness and acute toxicity 

for D. magna and occurred only when tests with 

less than 24-hr old neonates were included in the 

database. Accordingly, only the five D. magna 

tests from Chapman et al. (1980} initiated with 

less than 24-hr old neonates were used for the 

analysis

 Pg.33 Two species of sculpin, Cottus bairdii and 

Cottus confusus, are used to derive the 

normalized GMAV of 4.962 μg Cd/L

o **Per Appendix A, this value should be 

4.926**

 Pg.34 The hardness-normalized GMAV of 7.911

μg/L total cadmium for the genus Oncorhynchus 

is the fifth lowest in the acute dataset

o **Per Appendix A, this value should be 

7.841 **

 Pg.42 2. Ceriodaphnia, Cladoceran 

(GMCV=1.293μg/l total Cd)

 Pg. 74 Acceptable chronic toxicity data are 

available for 27 freshwater species representing 

20 different genera

 Pg. C-8 d Not used to calculate SMAV because 

either a more definitive value available, value is 

considered an outlier, or preference was given to 

the more sensitive exposure scenario (LC versus 

ELS tests).

The document was thoroughly reviewed prior to Federal Register 

publication. Typos and grammatical errors have been corrected and 

suggestions highlighted in your comments have been addressed.

Various locations
23

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

While Table 5 summarizes the Phyla, Families, 

Genera, and Species used to derive the revised 

criterion, it is unclear which species were used to 

meet each of the MDRs. Include a table that lists the 

eight requirements and the species used to fulfill them.

Table 5 has been modified to include the genus used to fulfill each 

of the family MDRs. 

Table 5

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

Verify that the Spehar and Fiandt 1986 data for 

Pimephales promelas is appropriate to include in the 

freshwater acute hardness correction.

The Spehar and Fiandt (1986) data for Pimephales promelas

satisfy the requirements for use in the freshwater acute slope 

derivation, and although the acute value for this study is lower than 

the other data evaluated at a similar hardness level, there is no 

justification for exclusion. Additional tables were added to 

Appendices A and C to list which studies and values were used in 

the respective hardness normalization analysis.

Appendix Table A-1, 

A-2, C-1 and C-2

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

Expand Table 6 to include the actual data that were

used in the freshwater acute hardness correction for 

each species.

An additional table was added to Appendix A to list which studies 

and values were used in the hardness normalization analysis. Appendix Table A-2 

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

Include a graph showing the freshwater acute 

hardness linear regression to better illustrate the 

normalization process.

A graph has been added showing the freshwater acute hardness 

linear regression to better illustrate the normalization process. Figure 2
24

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0006

Wisconsin 

Department of 

Natural 

Resources) 

Indicate how the R2value of 0.964 was obtained in the 

freshwater acute hardness correction. Attempts to 

replicate the value resulted in a slope of 1.104 and R2

of 0.698.

Indicate how the R2value of 0.841 was obtained in the 

freshwater chronic hardness correction. Attempts to 

replicate the value resulted in a slope of 0.798 and R2

of 0.632.

The differences in r2for both the acute and chronic hardness 

correction slopes represents differences in the models used to 

calculate these slopes. While the commenter manually normalized 

log transformed hardness and toxicity values by species prior to the 

regression (inferred from Figure 1 and 2), the draft document did 

not manually normalize to species, but rather used the following 

multiple linear regression model:

lnToxicity = Species + lnHardness;

Where “lnToxicity” represents either ln transformed acute or 

chronic toxicity values, as applicable.

The inclusion of a “Species” term in a multiple regression model 

prior to the lnHardness term returns a normalized hardness slope 

without having to manually normalize data to species, as shown by 

the equivalent hardness slopes calculated using the two 

approaches. The higher r2in the multiple regression model is due 

to the inclusion of the species term, as the effects of species are 

also accounted for in the model, but the hardness slopes are 

equivalent. This is the same approach used in the previous (2001)

cadmium criteria document. 

No edits

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

It was not apparent if the MATC or EC20 value was 

used for the freshwater chronic slope derivation. 

Indicate which of the toxicity values were used in the 

derivation in Appendix C and Table 8.

A table was added to Appendix C to list which studies, effect 

measurement and values were used in the hardness normalization 

analysis.

Appendix Table C-2 

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

Include a graph showing the freshwater chronic 

hardness linear regression to better illustrate the 

normalization process.

A graph has been added showing the freshwater chronic hardness 

linear regression to better illustrate the normalization process. Figure 4

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

The language that describes the computation of the 

final acute value on pg. 32 is insufficient. Include a 

reference to section 4.3.1 after the reference to Figure 

2 on page 32.

Reference to Section 4.3.1 has been added. Section 3.1.1
25

Comment 

Number Public Comment EPA Response

Revision Location 

in 2016 Cadmium 

Criteria Document

EPA-HQ-OW2015-0753-0006

(Wisconsin 

Department of 

Natural 

Resources)

It is unclear how the intercept of the freshwater acute 

and chronic criterion equations were derived. Add 

additional language to clarify how these values were 

derived.

The intercept and slope of the freshwater acute and chronic 

criterion equations were derived based on an analysis of the data as 

described in section 3.1.1 for acute freshwater, and section 3.1.2 

for chronic freshwater criteria. 

The intercepts can be calculated by rearranging the criterion 

equations for total cadmium and solving for the intercept. The 

constants/intercept in the equations for the CMC and CCC were 

derived as follows:

The total cadmium CMC= e(0.9789 x ln(hardness) – 3.866)

Where, 0.9789 is the acute pooled slope and -3.866 is calculated 

as

=ln(CMC at 100 hardness) - (Pooled Acute Slope x (ln(100)))

=ln(1.9)-(0.9789 x 4.605)

The dissolved cadmium CMC can be calculated by multiplying the 

total cadmium CMC by a conversion factor, CF

Acute CF= 1.136672 - [(ln hardness) x (0.041838)]

Similarly, the total cadmium CCC = e(0.7977 x ln(hardness) – 3.909)

Where, 0.7977 is the chronic pooled slope and;

-3.909 is calculated as

=ln(CCC at 100 hardness) - (Pooled Chronic Slope x (ln(100)))

=ln(0.79)-(0.7977 x 4.605)

The chronic total-to-dissolved CF = 1.101672 - [(ln hardness) x 

(0.041838)]

No edits