## EPA’s Review of Revised 2016 Freshwater Acute Cadmium Criterion for Oregon in

accordance with the Reasonable and Prudent Alternatives in the National Marine

Fisheries Service 2012 Biological Opinion on Oregon’s Toxic Water Quality Standards

The information pro vided in t his document addresses the process for deriving a criterion specified in the

reasonable and prudent alternative (RPA) for Oregon’s freshwater acute cadmium criterion, contained in the

National Marine Fisheries Service (NMFS) 2012 biological opini on. 1



### BACKGROUND INFORMATION

On May 20, 2004, the Oregon Environmental Quality Commission (EQC) adopted 89 new and revised criteria

for 25 chemicals . The freshwater acute cadmium (Cd) criterion was one of the revised criteria included in

Oregon’s adoption. Oregon submitted their revisions to the Environmental Protection Agency (EPA) for review

and action on July 8, 2004. At that time, the freshwater acute cadmium criterion adopted by Oregon was

consistent with the EPA’s 304(a) recommendation. 2



### The EPA subm itted a biological evaluation of the effects of the revised freshwater acute cadmium criterion to

the NMFS on January 14, 2008. On August 14, 2012, the NMFS completed their biological opinion and found

the revised freshwater acute cadmium criterion would j eopardize the continued existence of endangered

salmonids. The NMFS 2012 biological opinion contains a process for deriving a freshwater acute cadmium

criterion which is intended to avoid jeopardizing the continued existence of listed species or the destru ction or

adverse modification of designated critical habitat.

On January 31, 2013, EPA took formal action under the Clean Water Act to approve, in part, and disapprove, in

part, Oregon’s toxics criteria for aquatic life. EPA approved 38 of the 83 3 

### new and revised water quality criteria

and disapproved 45 of the 83 new and revised water quality criteria that Oregon adopted. The disapproval

action included the freshwater acute cadmium criterion that was evaluated in the NMFS jeopardy opinion.



## I. RPA ANALYSIS

I ntroduction:

The RPA steps in the NMFS 2012 biological opinion outlined a process for deriving a n acute cadmium

criterion (see Appendix A for the language contained in the RPA). The process can be summarized in the

following steps:

1. Use toxicity data specific to salmonids. If new toxicity data becomes available for green sturgeon and

eulachon then this data should be used in the analysis.

2. Toxicity data must be curve

- fitted where the literature provides the necessary raw data. Note: in this

document the term “curve

- fitted” is referred to as the “concentration

- response (C

- R) curve.”

3. The curve

- fitted data, or concentration

- response curve

, must be used to extrapolate a threshold acute

effects concentration. For example, if the threshold effect is considered to be at the LC 0 5



### , the

1 Jeopardy and Adverse Modification of Critical H abitat B iological O pinion for the Environmental protection Agency’s Proposed

Approval of Certain Oregon Administrative Rules Related to Revised Water Quality Criteria for Toxic Pollutants , NMFS

, August 14,

2012

.

2 EPA’s 304(a) recommendation was the 2001 Update of Ambient Water Quality Criteria for Cadmium

, EPA

- 822

- R

- 01

- 001, April 2001.

3 In 2007, Oregon made corrections to their water quality standards and inadvertently removed 6 aquatic life criteria from their

standards (acute and chronic freshwater and saltwater arsenic, and acute and chronic saltwater chromium VI). Therefore , in

, 2013,

EPA acted on 83 of Oregon’s original criteria (i.e., 89 minus 6). Oregon re

- adopted these 6 criteria into their wate r quality standards

in January 2014. EPA successfully completed ESA consultation and approved the re

- adoption of these 6 criteria in February 2014

.



### 1

### concentration on the curve associated with the LC 0 5 

### would be considered the threshold effect. 4 

### The

minimum effects threshold shall be used to derive the criteria instead of using the EPA acute adjustment

factor or the acute

- to

- chron ic ratio to derive criteria. 5



### 4. Derived criteria must be model

- adjusted to account for chemical mixtures.

5. An appropriate population model must be applied to the derived criteria, and must predict no negative

change in the intrinsic population growth rate.

S ection A below addresses RPA steps 1 through 3 (i.e., deriving an acute criterion based on the minimum

threshold effect from the co ncentration

- response curve), Section B addresses RPA step 4 (i.e., mixtures

analysis), and Section C addresses RPA step 5 (i. e., population model).

A. Process for Deriving Acute Cadmium Criterion from Toxicity Studies for Salmonids

EPA performed the followi ng C

- R curve analysis to derive minimum effect thresholds (i.e., LC 10 

### and LC 05 

### ) for

salmonids in order to meet RPA steps 1

- 3 (below) specifically pertaining to acute cadmium. As stated in the

NMFS 2012 biological o pinion:

“...EPA shall derive criteria for acute ammonia, acute cadmium, and acute and chronic aluminum in

compliance with the following five requirements:

1) Only use toxicity data for ammonia, cadmium, and aluminum that is specific to salmonid fishes

(if new information becomes available for these compounds for green sturgeon and eulachon,

then EPA shall include this data in its analysis);

2) All toxicity data u sed to derive the numeric criteria must be curve

- fitted, where the literature

provides the necessary data to perform this step;

3) When available, the curve

- fitted toxicity data must be used to extrapolate threshold acute and

chronic toxic effect concentrati ons;...”

When performing the C

- R analysis to fulfill the RPAs above, EPA also considered the acute aspects of the

specifics discussed in the NMFS 2012 biological o pinion below.

“More specifically, EPA shall ensure that the derived criteria are develope d in compliance with the

following mandatory sideboards:

The EPA shall use toxicity data specific to salmonid fishes. The EPA shall use the acute and chronic

toxicity data in this opinion as a minimum data set. For green sturgeon and eulachon, EPA shall use the

salmonid fishes toxicity data for this analysis, as described in section 2.6.2 in this opinion, in addition to

any new data that becomes available for green sturgeon and eulachon.

The EPA shall use toxicity data based on exposure

- res ponse curves and fixed duration toxicity tests to

estimate acute and chr onic toxic effect thresholds to assess effects on multiple life stages and multiple

endpoints, to include at a minimum: mortality, latent mortality, reproduction, growth, physiological,

cellular, behavioral, and biochemical effects, where the data exists. The EPA may use existing toxicity

data for ammonia, cadmium, and aluminum or generate new data, but the data shall be curve

- fitted (see

4 The LC 0 5 is the concentration of a pollutant that would be lethal to 5% of the individuals in toxicity tests.

5 If the raw data is provided in a toxicity test

, EPA can (1) calculate a concentration

- response curve for each individual toxicity test

using the Toxicity Relationship Analysis Program (TRAP, version 1.30a) to generate LC 0 5 and LC 10 values, and (2) use the

geometric mean of the LC 05 and LC 10 values for each genus or species (if only one genus) to generate a species distribution (SD )

curve (a minimum of 15 data points is needed to develop a SD ) to calculate the “minimum effect threshold” NMFS requested in

the RPA.



### 2

### Figure 2.6.1.1) to determine the minimum effect thresholds ( e.g. , 5%) at which acute and chronic toxic

effects are predi cted. The minimum effects thresholds shall be used to derive the criteria instead of using

the EPA acute adjustment factor or the acute

- to

- chronic ratio to derive criteria.”

EPA’s goal was to identify the minimum acute effect threshold for salmonids, stur geon, and eulachon exposed

to cadmium in freshwater per the RPAs provided by NMFS 2012 b iological o pinion. Specific EPA objectives

included:

1. Conduct a literature search for cadmium toxicity studies with green sturgeon and eulachon and review

them for technical adequacy according to the EPA

, Office of Water (OW)

, Aquatic Life Criteria

Guidelines (Stephen et al. 1985 )

. 6



### 2. For those green sturgeon and eulachon studies that meet test acceptability requirements and contain

enough data, calculate normalized C

- R curves.

3. Determine if EPA’s on

- line version of the Interspecies Correlation Estimation program (WebICE) can

be used to estimate cadmium

- specific LC 50 

### (s) for green sturgeon or eulachon if no acceptable acute

toxicity data exist.

4. Obtain the acute cadmium toxicity test data reported in the salmonid studies cited by EPA in the 304(a)

cadmiu m criteria document (dated March 2016), and, if sufficient data are available, calculate a

hardness

- normalized C

- R curve (at 100 mg/L hardness as CaCO 3 

### ) for each test.

a. Un fortunately, because the acute toxicity data tab les contained in the NMFS 2012 biological

o pinion largely did not specify test species or citations for toxicity values provided, EPA was

unable to use the ac ute toxicity data from the NMFS 2012 biological o p inion as a minimum data

set (as specified in RPA specifics above) . Consequently, EPA considered the high

- quality

salmonid toxicity data

, used to calculate the 2016 freshwater acute cadmium criterion that also

had availabl e raw data to perform C

- R analysis. The quality of toxicity data used in both criteria

derivation and C

- R analysis was assessed following the 1985 Guidelines

. 6



### 5. Identify the minimum effects thresholds (i.e., lethal or effect concentration, LC or EC, at the 5 or 10

percent response level) for each test based on the C

- R curve generated for all salmonid, green sturgeon

and eulachon studies, and, wh en estimating/extrapolating the minimum effect threshold s, note if there

are any technical or statistical issues. For example, note if the minimum eff ect threshold is estimated to

be below the control response or if the threshold lies beyond the bounds of what the data (statistically)

allow.

a. To access study

- specific data and summary sheets relating to the C

- R curve fit analysis, please

see the attached excel file entitle: C

- R Curve Fit Analysis Spreadsheets _A

.

Summary:

No acceptable studies were found in the literature search for acute (or chronic) cadmium toxicity to green

sturgeon or eulachon. The WebICE LC 50 

### values predicted for sturgeon at the genus ( Acipenser ) and family

level ( Acipenseridae) based on acute cadmium toxicity to Xyrauchen texanus (razorback sucker) were 23.28

and 23.73 μg/L ( dissolved Cd, hardness = 100 mg/L) , respectively. X. texanus was selected as the surrogate

species following WebICE model selection guidance. Given data limitations, WebICE could not estimate

cadmium toxicity to eulachon at the species, genus, or family

- level.

Twenty

- nine acute c admium toxicity tests from seven sa lmonid studies identified by EPA contained sufficient

data to generate a C

- R curve and calculate minimum effect thresholds ( see Table 1). The geometri c mean LC 10



### and LC 05 

### values for 28 of the 29 tests with no technical or statistical issues were 2.18 and 1 .89 μg/L total

cadmium normalized to 100 mg/L (as CaCO 3 

### ) hardness, respectively. The salmonid

- specific geometric mean

6 Stephan, C.E., D.I. Mount, D.J. Hansen, J.H. Gentile, G.A. Chapman, and W.A. Brungs. 1985. Guidelines for deriving numerical

national water quality criteria for the protection of aquatic organisms and their uses. PB85

- 227049. National Technical Information

Service, Springfield, VA. 98 pp.



### 3

### LC 10 

### and LC 05 

### values expressed as dissolved cadmium (after application of the conversion factor of 0.944), are

2.06 and 1.79 μg/L, respect ively . Using concentration

- response data, EPA also calculated the salmonid specific

LC 50 

### value to be 3.93 μg/L as total cadmium at a hardness of 100 mg/L (3.71 μg/L, dissolved cadmium; see

E xcel file entitle: C

- R Curve Fit Analysis Spreadsheets_A ).

EPA posted its final 304(a) national recommended cadmium criteria online on March 30, 2016 (EPA

- 820

- R

- 16

- 002). The acute criterion magnitude is 1.8 μg/L (dissolved cadmium at 100 mg/L hardness , EPA aquatic life

criteria are reported to two significant figu res ) and is equivalent to the salmonid LC 05 

### C

- R curve

- based

minimum effects threshold and more stringent than the salmonid LC 10 

### C

- R curve

- based minimum effects

threshold.

EPA notes that the full definition of the acute cadmium criterion includes frequency and duration aspects in

addition to magnitude (concentration) : the full definition of the acute cadmium criterion, based on the definition

given in Stephan et al. (1985) is that the one

- hour (duration) average concentration does not exceed the cr iterion

maximum concentration (CMC) more than once every three years (frequency) on the average. This is a

conservative approach that captures possible latent effects, considering that acute criteria are based on 96

- hour

continuous concentration laboratory exposure toxicity tests

.

When considering the magnitude and duration components of both acute and chronic cadmium criteria together,

EPA calculated (Equation 1) the acute magnitude may only be met for a total of < 14 hours before the chronic

criterion is exceeded.

Equation 1 : [>CCC] = [(CMC)(X)/96]

Where :

CCC = >0.25 μg/L = chronic criterion exceedance,

CMC = 1.8 μg/L = acute criterion magnitude,

96 = chronic criterion duration,

X= number of hours the acute criterion can be met before chronic criterion is exceeded.

As a result, considering only 96

- hour effect concentrations does not adequately account for additional

protection provided by the duration component of the acute cadmium criterion. Therefore, 14

- hour LC 50 

### values

may better reflect magnitude a nd duration components of the crite rion; however, such data remain largely

unreported. For comparative purposes, EPA calculated 14

- hour acute cadmium LC 50 

### values from two studies

used in the C

- R analysis where data permitted (Table 1, Stratus Consulting 19 99, Tests 9901 for rainbow trout

and bull trout ). These particular tests were chosen to derive 14

- hour LC 50 

### values because they calculated LC 50 

### values for multiple exposure durations using empirically measured toxicity data

. Availability of empirically

measured toxicity data at multiple exposure durations is necessary before LC 50 

### values can be estimated for

exposure durations for which empirical data are unavailable, such as 14 hour exposures.

The specific data from the Stratus Consulting (1999) study u sed in the calculation of 14

- hour LC 50 

### values were

t oxicity tests termed test phase 9901, specifically those performed in water with a pH = 7.5, hardness = 30 .7

mg/L as CaCO 3



### , and water temperature of 8°C. These pH and water hardness values are nearly iden tical to the

mean water chemistry conditions in the Willamette River at Portland, Oregon, part of a major migration route

for multiple salmonid species. For both bull trout and rainbow trout, Stratus Consulting (1999) calculated LC 50 

### values for 48, 60, 72, 84, 96, 108, 120, 132 and 144 hour exposures to acutely toxic cadmium concentrations.

A graph of LC 50 

### concentration s on the y

- axis and exposure durations on the x

- axis yields a curve , termed a

time

- to

- effect curve, where LC 50 

### conc entration s are higher at shorter exposure durations than they are at longer

exposure durations. V isually , such a graph looks similar to an exponential decay curve , where the LC 50 

### values

4

### eventually become asymp totic to the x

- axis. The LC 50 

### concentration at the asymptote to the x

- axis (exposure

duration) is the incipient lethal level. Multiple statistical methods have historically been employed to fit time

- to

effect curves, including exponential, hyperbolic and polynomial regressions, as wel l as Micha e lis

- Menten

kinetic and power functions. Once a cur ve has been fit to time

- to

- effect data, the curve can be ex trapolated in

both directions. Extrapolation to longer exposure durations result in the calculation of the incipient lethal level,

where as extrapolation to shorter exposure durations permit calculation of LC 50 

### values for shorter exposure

durations than were estimated from empirically recorded toxicity test data.

EPA has determined that for the Stratus Consulting (1999) bull trout and rain bow trout toxicity data, a

polynomial regression provided t he best fit of the time

- to

- effect data for both bull trout and rainbow trout, with

coefficients of variation (r 2 

### ) greater than 0.99 for both data sets. Once normalized to a hardness of 100 mg/L as

CaCO 3 

### , the c alculated 14

- hour cadmium LC 50 

### values for rainbow trout and bull trout were 13.77 μg/L and

40.20 μg/L (dissolved Cd ), respectively. The 14

- hour rainbow trout LC 50 

### values is 73 % greater than the 96

- h our

salmonid

- mean LC 50 

### (i.e., 3.71 μg/L, dissolved cadmium, hardness = 100) , while the 14

- hour bull trout LC 50 

### is

more than 90% greater than the salmonid

- mean 96

- hour LC 50 

### value.

It is important to reiterate that the acute criterion duration is only one ho ur, not 14 hours. Therefore, 14

- hour

acute criterion exposures could not occur continuously , as was the case in t oxicity tests used to calculate 14

-

hour LC 50 

### values

. EPA further extrapolated along the time

- to

- effect curve to specifically capture the one hour

duration specified in the acute cadmium criterion. One

- hour LC 50 

### values for rainbow trout and bull trout are

18.85 μg/L and 66.88 μg/L (dissolved cadmium, hardness = 100 mg/L), respectively.

Regardless of variable exposure duration, t he magnitude component of the 2016 acute criterion of 1.8 μg/L

(dissolved cadmium at 100 mg/L hardness) is equal to the salmonid minimum effects threshold NMFS specified

th at EPA should use to derive the acute cadmium criterion. (From the NMFS 2012 biological opinion : “ The

minimum effects thresholds shall be used to derive the criteria instead of using the EPA acute adjustment factor

or the acute

- to

- chronic ratio to derive criteria.” )

. Based on this analysis, EPA concludes that RPA steps 1

- 3,

are met.

5

### Table 1 . Summary of LC 10 

### and LC 05 

### Values Calculated for 29 Tests with Available C

- R data from seven Acceptable Studies Investigating the

Acute Toxicity of Cadmium to Salmonids (studies from Ap pendix A of the 2016 304(a) cadmium aquatic life c riteria document).

Study Species

(common) Test

Description Hardness

(mg/L) Dissolved? Unadjusted 1 Unadjusted

(Tot al 2 ) Hardness

Normalized

(Total) 3 Species

- Study

Geometric Mean TRAP

Flags 4 Exclude Comments LC10 LC05 LC10 LC05 LC10 LC05 LC10 LC05

Besser et al.

2007 Rainbow trout Acute 2 103 yes 2.578 2.370 2.730 2.510 2.652 2.438

3.197 2.964 IP

Acute 3 103 yes 3.64 3.327 3.855 3.523 3.744 3.422 IP, no

convergence yes No model

convergence

Acute 4 103 yes 3.747 3.503 3.968 3.710 3.854 3.603 large SE

–

X50 & S

Brinkman

2012 Rio Grande

cutthroat trout 44.9 yes 3.509 3.275 3.607 3.367 7.898 7.371 7.898 7.371 IP, no CI

Davies et al.

1993 Acute 1

– 200H, 30

alk see notes no see

notes see

notes 0.392 0.289 Hardness differed

for individual conc.,

was normalized

prior to TRAP.

Hardness >50 from

Mg, not CaCO3.

Acute 2

– 200H, 30

alk see notes no see

notes see

notes 1.303 1.080 Hardness differed

for individual conc.,

was normalized

prior to TRAP.

Hardness >50 from

Mg, not CaCO3.

Acute 1

– 50H, 30 alk see notes no see

notes see

notes 4.332 3.963 Hardness differed

for individual conc.,

was normalized

prior to TRAP.

Hardness >50 from

Mg, not CaCO3.

Source water

hardness = 45

mg/L.

Acute 2

– 50H, 30 alk see notes no see

notes see

notes 5.661 5.337 IP, no CI Hardness differed

for individual conc.,

was normalized

prior to TRAP.

Hardness >50 from

Mg, not CaCO3.

Source water

hardness = 45

mg/L.

Rainbow trout Acute 1

– unaged hard 281 yes 9.966 9.434 10.893 10.311 3.961 3.750 3.225 2.845

no CI



### 6Study Species

(common) Test

Description Hardness

(mg/L) Dissolved? Unadjusted 1 Unadjusted

(Tot al 2 ) Hardness

Normalized

(Total) 3 Species

- Study

Geometric Mean TRAP

Flags 4 Exclude Comments LC10 LC05 LC10 LC05 LC10 LC05 LC10 LC05

Davies and

Brinkman

1994b Acute 2

– unaged hard 281 yes 6.000 5.298 6.558 5.791 2.385 2.106

Acute 1

– aged hard 258 yes 3.334 2.641 3.644 2.887 1.441 1.141 IP Retained, but

flagged due to

uncertainty of

response between 2

highest conc.

Acute 2

– aged hard 276 yes 6.924 6.121 7.568 6.690 2.801 2.476 IP, large SE

– X50 & S

Acute 1

– unaged soft 29 yes 1.890 1.726 1.943 1.774 6.526 5.960 no CI

Acute 2

– unaged soft 28 yes 1.266 1.116 1.301 1.147 4.524 3.988

Phipps and

Holcombe

1985 Rainbow trout 44.4 no 1.955 1.759 1.955 1.759 4.328 3.894 4.328 3.894

Stratus

Consulting

1999

Bull trout Bank 1

– Bull, H30.7,

pH 7.5,

9901 30.7 no 0.685 0.643 0.685 0.643 2.177 2.044

2.412 2.111 no CI

Bank 2

– Bull, H89.3,

pH 7.54,

9901 89.3 no 3.146 2.705 3.146 2.705 3.514 3.021

Bank 3

– Bull, H30,

pH 6.65,

9901 30 no 1.502 1.255 1.502 1.255 4.880 4.078

Bank 3

– Bull, H29.3,

pH 7.56,

9905 29.3 no 0.526 0.453 0.526 0.453 1.747 1.506

Bank 2

– Bull, H33.7,

pH 7.58,

9908 31.7 no 0.443 0.366 0.443 0.366 1.365 1.126

Bank 3

– Bull, H30.2,

pH 7.57,

9908 30.2 no 0.685 0.642 0.685 0.642 2.211 2.072 IP, no CI

Rainbow trout Bank 1

– RBT,

H30.7, pH

7.51, 9901 30.7 no 0.393 0.349 0.393 0.349 1.250 1.110 0.995 0.845



### 7Study Species

(common) Test

Description Hardness

(mg/L) Dissolved? Unadjusted 1 Unadjusted

(Tot al 2 ) Hardness

Normalized

(Total) 3 Species

- Study

Geometric Mean TRAP

Flags 4 Exclude Comments LC10 LC05 LC10 LC05 LC10 LC05 LC10 LC05

Stratus

Consulting

1999 (Cont.) Bank 2

– RBT,

H89.3, pH

7.52, 9901 89.3 no 1.059 0.827 1.059 0.827 1.183 0.924

Bank 3

– RBT, H30,

pH 6.66,

9901 30 no 0.413 0.319 0.413 0.319 1.341 1.037

Bank 3

– RBT,

H29.3, pH

7.39, 9905 29.3 no 0.242 0.212 0.242 0.212 0.804 0.706

Bank 2

– RBT,

H31.7, pH

7.43, 9908 31.7 no 0.251 0.217 0.251 0.217 0.774 0.669

Bank 3

– RBT,

H30.2, pH

7.42, 9908 30.2 no 0.244 0.224 0.244 0.224 0.788 0.722

Stubblefield

1990 (ENSR) Brown trout 48 no 1.190 0.977 1.190 0.977 2.441 2.004 2.441 2.004

Rainbow trout 52 no 0.716 0.585 0.716 0.585 1.358 1.109 1.358 1.109

Mountain

Whitefish 52 no na na na na yes No C

- R

relationship.

Toxicity assay not

included as one of

29 tests with

sufficient C

- R data.

1

– When multiple TRAP model solutions were available, the model that most effectively fit the low effect range was selected.

2

– For those studies where unadjusted LCx values were calculated on the basis of dissolved cadmium because only measured dissolv ed cadmium concentrations were reported,

the LCx values were converted to total cadmium (see Unadjusted Total) using conversion factors of 1.028, 1.059 and 1.093 for tota l hardness levels closest to 50, 100 and 200

mg/L, respectively. The approach and conversion factors are consistent with approach a nd conversion factors used in Appendix A of the 2016 ALC document.

3

– Hardness normalizati on equation= EXP(0.9789*4.605+( ( LN(LC50))

- (0.9789*(LN(hardness)))) based on acute Cd toxicity

- hardness pooled slope of 0.9789 derived March

2016

4

– IP (inadequate p artial responses), no convergence (model could not converge to a solution), no CI (confidence intervals could not be calculat ed), large SE (large standard error

for X50 (EC50) or S (slope) parameter)



### 8

# C B. Mixture Analysis

The information provided in this section a ddresses RPA s tep 4 contained in the NMFS 2012 biological

opinion. RPA step 4 pertains specifically to ensuring the acute cadmium criterion is adjusted, as necessary,

to account for pollutant mixtures in freshwaters. The RPA inclu des the following language:

EPA shall ensure that each derived criterion for ammonia, cadmium, and aluminum is adjusted to

account for chemical mixtures using a concentration

– addition model or response

- addition model

to determine whether or not exposure t o multiple compounds will result in additive effects to the

listed species considered in this opinion. The concentration

– addition model or response

- addition

model shall include all compounds listed in Table 1.1. If the mixture effects prediction is greater

than one, EPA shall adjust the concentrations for ammonia, cadmium, and aluminum until the

mixture effects prediction is less than one.

The NMFS 2012 b iologi cal o pinion assumed the following mixture of pollutants would occur in a

waterbody

. Therefore, EP A used the following pollutants (below) in the mixture analysis consistent with

the approach outlined in the NMFS 2012 biological o pinion :

Aluminum Copper

Arsenic Cadmium

Chromium III Lead

Nickel Selenium

Chromium VI Silver

Tributyltin Zinc

EPA used the following equation, specified in the NMFS 2012 biological opinion for the mixtures analysis

(below):

Equation 2 :

ECx Mix =



### Where : 

## n 

# ∑

I

= 1 I 

# EC

xi



### 9

### n = the number of compounds in the mixture,

C i 

### = assessment exposure concentration (acute criterion),

E C xi 

### = assessment lethal effects concentration (geometric mean of the criterion

- specific toxicity data set).

EC

x Mix 

### = the sum of toxic units in the mixture, where a toxic unit (TU) is defined as C i 

### /EC xi



### In calculating the acute criterion

- specific EC xi 

### values (geometric mean of LC 50 

### values from acute toxicity

tests) in the table below, EPA used LC 50 

### effect concentrations from acute tests with salmonid fishes,

supplied in Tables 2.6.2.2.1.1 through 2.6.2.2.12.1 of the NMFS 2012 biological opinion for aluminum,

arsenic, chromium III an d VI, lead, nickel, selenium, silver, tributyltin and zinc. In a number of these tables

(e.g., Tables 2.6.2.2.1.1 through 2.6.2.2.12.1; aluminum, arsenic, nickel, selenium, silver, tributyltin and

zinc), NMFS included effect concentrations from chronic tes ts and tests for which there is no test duration

information when calculating geometric mean LC 50 

### values. Because NMFS concluded the chronic cadmium

criteria is adequately protective of salmonid species, EPA only considered effect concentrations from acute

tests when calculating the acute criterion

- specific EC xi 

### for each chemical used in the mixture analysis. As a

result, the geometric mean values for aluminum, arsenic, nickel, selenium, silver, tributyltin and zinc in the

table below are different than the geometric mean values presented in Tables 2.6.2.2.1.1 through Table

2.6.2.2.12.1 of the NMFS 2012 biological opinion . With respect to the acute criterion

- specific EC xi 

### values

for copper and cadmium, EPA utilized acute toxicity data (LC 50 

### ) for salmonids fr om EPA’s updated 304(a)

criteria documents. Specifically, EPA considered acute cadmium salmonid data used to calculate the acute

cadmium 304(a) criterion value. Using this information and the equation above, EPA calculated a mixture

effects prediction resu lt of 0.944.

1. Tables 2.6.2.2.1.1 through 2.6.2.2.12.1 of the NMFS 2012 biological opinion included data for salmonids, eulachon and green

sturgeon, but the tables do not provide references or specify which tests are associated with which species. Therefore EPA

used all of LC 50 effect concentrations in the tables, with the exception of c hronic test data and data where test duration was not

identified.

2. Metals criteria calculated assuming a hardness of 100 mg/L CaCO 3.

3. Acute criterion was derived using EPA’s 2007 freshwater copper criterion (biotic ligand model) using input values based on

Oregon

- specific ecoregion data (i.e., 10 th percentile of existing concentrations of DOC, calcium, magnesium, sodium,

potassium, sulfate, chloride, pH, temperature and alkalinity from Oregon’s Level III ecoregions)

. Chemical Acute

Criterion

(C i ) (μg/L) Acute EC xi TU

Aluminum 1 750 4275 0.175

Arsenic 1 340 12917 0.026

Cadmium 2, 1.8 5.9 0.305

Chromium III 1,2 570 9825 0.058

Chromium VI 1 16 68333 0.000

Copper 5.14 3 96.00 0.054

Lead 1,2 65 14675 0.004

Nickel 1,2 470 29548 0.016

Selenium 1 190 3945 0.048

Silver 1,2 3.2 67.55 0.047

Tributyltin 1 0.46 4.31 0.107

Zinc 1,2 120 1162.81 0.103

EC xMix 0.944

10

### Summary:

The result of the mixtures analysis is less than 1. Salmonids exposed to multiple pollutants , including cadmium,

in freshwaters are unlikely to suffer toxicity greater than the assessment effect concentrations. In addition to

multiple metals, the mixtures analysis also considered an algaecide ( tributyltin ; TBT ) most commonly detected

in oceans and estuaries. Therefore, the mixtures analysis (section B) may overestimate mixture toxicity in

freshwaters. Based on the Section B mixtures analysis, EPA concludes RPA step 4 is met.

11

### Table 2. Freshwater Salmonid Acute Toxicity Data Used for RPA (s tep 4) Mixtures Analysis

Species Chemical Hardness

(mg/L CaCO 3 ) Acute Value

(μg/L , Total ) Normalized Acute

Value 1

(μg/L , dissolved ) Reference

Rio Grande cutthroat trout

(fry, 0.26 g),

Oncorhynchus clarkii virginalis Cadmium

sulfate 44.9 2.467

(2.40 reported dissolved) 5.099 Brinkman 2012

Coho salmon (parr),

Oncorhynchus kisutch Cadmium

chloride 22 2.7 11.215 Chapman 1975

Rainbow trout (130 mm),

Oncorhynchus mykiss Cadmium

sulfate 31 1.75 5.198 Davies 1976a

Rainbow trout

(swim

- up fry, 0.17 g),

Oncorhynchus mykiss Cadmium

chloride 23 1.3 5.172 Chapman 1978

Rainbow trout (parr, 6.96 g),

Oncorhynchus mykiss Cadmium

chloride 23 1.0 3.978 Chapman 1978

Rainbow trout (8.8 g),

Oncorhynchus mykiss Cadmium

chloride 44.4 3.0 6.269 Phipps and

Holcombe 1985

Rainbow trout

(juvenile, 18.3 g),

Oncorhynchus mykiss Cadmium

chloride 52 1.88

3.365 Stubblefield 1990

Rainbow trout (1.8 g),

Oncorhynchus mykiss - 47 2.66 5.257 Davies et al. 1993

Rainbow trout (1.8 g),

Oncorhynchus mykiss - 204 3.15 1.479 Davies et al. 1993

Rainbow trout (1.8 g),

Oncorhynchus mykiss - 49 3.02 5.730 Davies et al. 1993

Rainbow trout (1.8 g),

Oncorhynchus mykiss - 224 6.12 2.623 Davies et al. 1993

Rainbow trout (fry, 1.0 g),

Oncorhynchus mykiss Cadmium

sulfate 29 2.79 8.846 Davies and Brinkman

1994b

Rainbow trout (fry, 2.5 g),

Oncorhynchus mykiss Cadmium

sulfate 258

(aged solution) 8.54 3.187 Davies and Brinkman

1994b

Rainbow trout (fry, 2.5 g),

Oncorhynchus mykiss Cadmium

sulfate 281 13.4 4.600 Davies and Brinkman

1994b

Rainbow trout (fry, 1.0 g),

Oncorhynchus mykiss Cadmium

sulfate 28 2.09 6.858 Davies and Brinkman

1994b

Rainbow trout (fry, 2.5 g),

Oncorhynchus mykiss Cadmium

sulfate 276

(aged solution) 10.5 3.668 Davies and Brinkman

1994b

Rainbow trout (fry, 2.5 g),

Oncorhynchus mykiss Cadmium

sulfate 281 10.0 3.433 Davies and Brinkman

1994b

Rainbow trout (263 mg),

Oncorhynchus mykiss Cadmium

chloride 30.7 0.71 2.129 Stratus Consulting

1999

Rainbow trout (659 mg),

Oncorhynchus mykiss Cadmium

chloride 29.3 0.47 1.475 Stratus Consulting

1999

Rainbow trout (1,150 mg),

Oncorhynchus mykiss Cadmium

chloride 31.7 0.51 1.482 Stratus Consulting

1999

Rainbow trout (1,130 mg),

Oncorhynchus mykiss Cadmium

chloride 30.2 0.38 1.158 Stratus Consulting

1999

Rainbow trout (299 mg),

Oncorhynchus mykiss Cadmium

chloride 30.0 1.29 3.956 Stratus Consulting

1999

12Species Chemical Hardness

(mg/L CaCO 3 ) Acute Value

(μg/L, Total) Normalized Acute

Value 1

(μg/L, Dissolved) Reference

Rainbow trout (289 mg),

Oncorhynchus mykiss Cadmium

chloride 89.3 2.85 3.005 Stratus Consulting

1999

Rainbow trout

(swim

- up fry, 0.131 g),

Oncorhynchus mykiss - 103 3.7

3.393 Besser et al. 2007

Rainbow trout

(juvenile, 0.496 g),

Oncorhynchus mykiss - 103 5.2

4.768 Besser et al. 2007

Rainbow trout

(18 dph, 0.1 g, 24.33 cm),

Oncorhynchus mykiss Cadmium

chloride 104 3.061

(2.89 reported dissolved) 2.780 Calfee et al. 2014

Rainbow trout

(32 dph, 0.12 g, 26.67 cm),

Oncorhynchus mykiss Cadmium

chloride 107 5.115

(4.83 reported dissolved) 4.518 Calfee et al. 2014

Rainbow trout

(46 dph, 0.22 g, 32.1 cm),

Oncorhynchus mykiss Cadmium

chloride 107 2.933

(2.77 reported dissolved) 2.591 Calfee et al. 2014

Rainbow trout

(60 dph, 0.33 g, 37.1 cm),

Oncorhynchus mykiss Cadmium

chloride 104 3.929 f

(3.71 reported dissolved) 3.568 Calfee et al. 2014

Rainbow trout

(74 dph, 0.42 g, 40.3 cm),

Oncorhynchus mykiss Cadmium

chloride 96 4.808

(4.54 reported dissolved) 4.723 Calfee et al. 2014

Rainbow trout

(95 dph, 0.7 g, 45.43 cm),

Oncorhynchus mykiss Cadmium

chloride 103 3.135

(2.96 reported dissolved) 2.874 Calfee et al. 2014

Rainbow trout

(juvenile, 26 dph),

Oncorhynchus mykiss Cadmium

chloride 100 5.401

(5.1 reported dissolved) 5.099 Wang et al. 2014a

Chinook salmon (juvenile),

Oncorhynchus tshawytscha Cadmium

chloride 25 1.41 5.170 Chapman 1978; 1982

Chinook salmon

(swim

- up fry, 0.23 g),

Oncorhynchus tshawytscha Cadmium

chloride 23 1.8

7.161 Chapman 1978

Chinook salmon (juvenile),

Oncorhynchus tshawytscha Cadmium

sulfate 21 1.1 4.784 Finlayson and Verrue

1982

Lake whitefish

(yearling, 140 mm, 22 g),

Coregonus clupeaformis - 81 530 614.827 McNicol 1997

Mountain whitefish (209 g),

Prosopium williamsoni Cadmium

chloride 52 >8.29 >14.839 Stubblefield 1990

Brown trout

(fingerling, 22.4 g),

Salmo trutta Cadmium

chloride 48 2.85

5.518 Stubblefield 1990

Brown trout (fingerling),

Salmo trutta Cadmium

sulfate 37.6 2.37 5.827 Davies and Brinkman

1994c

Brown trout (fry),

Salmo trutta Cadmium

sulfate 29.2 1.23 3.874 Brinkman and

Hansen 2004a; 2007

13Species Chemical Hardness

(mg/L CaCO 3 ) Acute Value

(μg/L, Total) Normalized Acute

Value 1

(μg/L, Dissolved) Reference

Brown trout (fry),

Salmo trutta Cadmium

sulfate 67.6 3.9 5.401 Brinkman and

Hansen 2004a; 2007

Brown trout (fry),

Salmo trutta Cadmium

sulfate 151 10.1 6.368 Brinkman and

Hansen 2004a; 2007

Bull trout (76.1 mg),

Salvelinus confluentus Cadmium

chloride 30.7

(pH=7.5) 0.91 2.729 Stratus Consulting

1999

Bull trout (200 mg),

Salvelinus confluentus Cadmium

chloride 29.3

(pH=7.5) 0.99 3.108 Stratus Consulting

1999

Bull trout (221 mg),

Salvelinus confluentus Cadmium

chloride 31.7

(pH=7.5) 1.00 2.907 Stratus Consulting

1999

Bull trout (218 mg),

Salvelinus confluentus Cadmium

chloride 30.2

(pH=7.5) 0.90 2.742 Stratus Consulting

1999

Bull trout (84.2 mg),

Salvelinus confluentus Cadmium

chloride 30.0

(pH=6.5) 2.89 8.864 Stratus Consulting

1999

Bull trout (72.7 mg),

Salvelinus confluentus Cadmium

chloride 89.3

(pH=7.5) 6.06 6.390 Stratus Consulting

1999

Brook trout

(yearling, 21 cm, 110 g),

Salvelinus fontinalis - 45

(44

- 46) >405 >835.25 Drummond and

Benoit 1976

Brook trout (100 g),

Salvelinus fontinalis Cadmium

chloride 47.4 5,080 9,957.3 Holcombe et al. 1983

1. 

### Values under the heading “Normalized Acute Value” have been normal ized to a hardness of 100 mg/L

and are presented as dissolved cadmium.

a) 

### Hardness normalizatio n equation = EXP(0.9789*4.605+(( LN(LC50))

- (0.9789*(LN(hardness))))

b) 

### Total to dissolved adjustment factor (at hardness = 100 mg/L) = 0.944

14

### C. Population Model

The information provided in this section addresses RPA step 5 contained in the NMFS 2012 biological opinion.

RPA step 5 pertains specifically to assessing the potential effects of cadmium on salmonids at the population

level. The RPA includes the following language:

To ensure that the derived numeric criteria for ammonia, cadmium, and aluminum meet the population

growth rate condition of the RPA, EPA shall run the criteria for ammonia, cadmium, and aluminum

through a population model (e.g., Leslie Matrix), parameterized for Pacific salmonid fishes. Model

requirements include: (1) scenarios based on change in first year survival; (2) an assumption that the

populations are density

- independent, to reduce the probability of Type II errors; (3) sigmoid slopes are

generated from the data used to derive the numeric criteria, and if a slope cannot be generated from the

data, EPA shall use the default sigmoid slope of 3.6 used in this opinion; and (4) exposure

- response

scenarios using the geometric mean of the curve

- fitted data, and the minimum species mean value of the

curve

- fitted data from the toxicity data used to derive the numeric criteria.



### Population Model Methods:

Of the 28 acceptable 96

- hour toxi city studies used to calculate minimum effect thresholds (Section A), 26 were

model

- compatible (Table 3). For population model analysis, EPA included all 96

- hour acute values (i.e.

, 96

- hour

LC 50 

### ) from tests using fish in the 0

- 10g range (i.e., juve nile or first

- year fish). EPA specifically considered 0

- 10g salmonid fishes because population

- level effects predicted from the model are most sensitive to first

- year fish

survival (See 2012 NMFS biological opinion, Appendix III, Table A

- 1). Most importantly, the model uses the

acute exposure

- response relationship from the toxicity data to adjust only the f irst

- year survival parameter. Thus, it

would be inappropriate to apply test results from other salmonid life stages to any surviva l response to first

- year fish.

Toxicity t ests not included in population modeling were those that used large juvenile fish ( i.e., second

- year

juveniles based on size and/o r weight ), or adult fish. Toxicity test data (e.g., 96

- hour LC 50 

### ) inclu ded in the

po pulation model dataset was obtained from tests using rainbow trout, Rio Grande cutthroat trout , and bull trout

(geometric mean 96

- hour LC 50 

### = 3.572 μg/L

, dissolved Cd , hardness = 100 mg/L ). The minimum species mean

value ( 96

- hour LC 50 

### ) of all included species was for rainbow trout (rainbow trout geometric mean 96

- hour LC 50 

### = 3.36 μg/L

, dissolved Cd, hardness = 100 mg/L). All 96

- hour LC 50 

### values were converted to total cadmium (as

necessary), then adjusted to hardness of 100 mg/L CaCO 3 

### , and finally converted back to the dissolved fraction

, consistent with approach and conversion factors use d in Appendix A of the 2016 aquatic life criteria document.

Concentration

- response relationships were es timated using raw data from acceptable toxicity tests (Table 3)

using the following two parameter logistic function (Equation 3) :

Equation 3 : percent survival = 100/(1+(concentration/LC 50 

### )^slope),

where survival (as percent) and concentration ( μg/L dissolved Cd ) were regressed to generate LC 50 

### and slope

estimates for each toxicity test in Table 3. The geometric mean of all calculated 96

- hour LC 50 

### values and slope

values, as well as the minimum species mean value (i.e., rainbow trout geometric mean 96

- hour LC 50 

### ) and

corresponding slope value, we re used as input for the population model. The geometric mean of the model

compatible 96

- hour LC 50 

### data is 3.572 μg/L (dissolved Cd, hardness = 100 mg/L) and the geometric mean slope

of concentration

- response test data is 4.978 (unitless). The minimum spec ies mean 96

- hour LC 50 

### value is 3.360

μg/L (dissolved Cd, hardness = 100 mg/L), with a slope of 4.562.

E PA ran four additional model scenarios based on 14

- hour and 1

- hour acute LC 50 

### values (see Section A) and

slopes for rainbow trout and bull trout (Stratus Consulting 1999). EPA used 14

- hour and 1

- hour LC 50 

### values, when

15

### available, to understand population

- level effects of cadmium, when the population model more accurately reflects

th e acute cadmium criterion by considering the duration component (i.e., averaging period) of the criterion.

Population models based on 14

- hour LC 50 

### values were selected to represent acute exposure scenarios that could

occur without exceeding the chronic cadmium criterion. Specifically, the acute criterion magnitude (i.e.,

concentration) could only be met for < 14 hours throughout the chronic criterion duration (i.e., 96 hours) before the

chronic criterion is exceeded, assuming cadmium concentrations are 0 .0 μg/L for the remaining 8 2 hours of the

chronic criterion duration.

Notably, 14

- hour continuous acute exposures would exceed the acute cadmium criterion by exceeding the duration

component, even though the magnitude component remains at criterion concen trations. Therefore, 1

- hour LC 50 

### values represent the maximum continuous acute cadmium exposure allowed by the acute cadmium criterion (i.e.,

1.8 μg/L dissolved Cd at hardness = 100 mg/L for 1 hour). As a result, p opulation model run s using 1

- hour LC 50



### values explicitly reflect the acute criterion duration

.

EPA is currently undergoing analyses to explore potential methods for accurately considering excursion frequency

in the population model. P otential methods for accurately considering the frequency c omponent of the acute

criterion remain preliminary and are therefore not presented here.

In total, EPA ran the population model under six scenarios:

1. Juvenile, salmonid

- mean 96

- hour LC 50 

### with corresponding slope

2. Juvenile, 96

- hour lowest salmonid species mean value (i.e.

, rainbow trout) with corresponding slope

3. Juvenile, rainbow trout 14

- hour LC 50 

### with corresponding slope

4. Juvenile, bull trout 14

- hour LC 50 

### with corresponding slope

5. Juvenile, rainbow trout 1

- hour LC 50 

### with corresponding slope

6. Juvenile, bull trout 1

- hour LC 50 

### with corresponding slope

Each model scenario (above) was run for four salmonid life histories :

1. Chinook, ocean type

2. Chinook, stream type

3. Coho

4. Sockeye

Population Model Results:

All four salmonid life

- history models using the salmonid geometric mean 96

- hour LC 50 

### value predict three percent

mortality with a negative change in the mean population growth rate (lambda) of one percent. Using the 96

- hour minimum species mean LC 50 

### value, the four salmonid life

- history models predict five percent mortality

with a negative change in lambda ranging from one to two percent.

The primary output of the p opulation model is a mean lambda value calculated from 10,000 individual model

iterations; the variation in the iterations themselves provides an estimate of overall model variability. Figure 1

shows histograms summarizing individual model iterations for a control population of ocean

- type chinook

(chinookot

c 

### in blue) and a population exposed to cadmium (chinookot

e 

### in yellow )

. T o generate Figure 1 data,

t he chinook (ocean type life history) population model was run using the geomean LC 50 

### value based on 0

- 10g

salmonid fish es exposed to cadmium for 96 continuous hours

. Histograms for lambda estimates from control

and exposed populations overlap to the extent it is visually difficult to distinguish the two

. The h istograms

suggest there is no detectable difference between the model output of lambda for a control population and a

population exposed to cadmium at the proposed criterion magnitude over exposure durations (i.e., 96 hours)

and excursion frequencies that are inconsistent with the acute cadmium criterion. Model output indicated a

16

### change in lambda of 1 % b etween control and exposed mean lambda estimates of chinook (ocean type)

populations, while also specifying a change in lambda of 12.7 % is required to detect a significant change

between the control and exposed mean lambda estimates. For all life history and exposure scenario model

runs, the change in lambda between control and exposed populations never exceeded one standard deviation

of the control lambda.

When using LC 50 

### data that more accurately consider the duration component of the acute cadmium criterion

(i.e., 14

- hour LC 50 

### values for rainbow trout and bull trout), the model predicts zero mortality and no negative

change in lambda for each fish life history model run (Table 4). Similarly, when using LC 50 

### data that

accurately consider the duration component of the acute cadmium criterion (i.e., 1

- hour LC 50 

### values for

rainbow trout and bull trout), the model also predicts zero mortality and no negative change in lambda f or

each fish life history model run (Table 4).

Summary:

The ability of the population model to detect a population

- level effect from cadmium exposure is limited given

the variability of the control population lambda values determined from 10,000 model iterations

. Variation in

both control and exposed lambda values results from the underlying variation associated with the demographic

information used to parameterize the model matrix. Appendix 3 of the NMFS 2012 biological opinion , which

describes the tec hnical details of the population model, states (pg

. 750):

The percent change in lambda is considered different from control when the difference is greater than the

percent of one standard deviation of the control lambda.



### In other words, the difference between the mean lambda of the control population and the mean lambda of the

exposed population must be greater than one standard deviation of the distribution of control lambda values in

order to statistically tell them apart (note: these values are provided in the model out put and are shown in Table

4).

For each life history, the model provides a summary estimate of the inherent uncertainty in its estimate of

change in lambda between the control and exposed scenarios (i.e., the percent change in lambda)

. F or all

scenarios run (see Table 4 ) , values of the percent change in lambda representing a significant change range from

4.3 to 12.9 percent. In other words, the population model is n ot adequately sensitive to identify differences in

lambda that may be caused by cadmium exposure if the threshold for acceptance is “no net negative change

. ” If

the threshold of acceptance is mean exposed population lambda values falling within one standar d deviation of

the control population lambda means (as noted in Appendix 3 of the NMFS 2012 biological opinion) , the n all

population model scenarios run for each s almonid life history suggest no population

- level effects of cadmium.

Using toxicity estimates based on 96

- hour exposures in the population model results in overly conservative

model output that does not reflect how duration and frequency components of the acute cadmium criterion

further protect salmon populations, in addition to the crite rion magnitude

. 

### EPA believes that incorporating

frequency and duration aspects into the population model is consistent with the RPA. Therefore, EPA also ran

the population model using 14

- hour and 1

- hour toxicity data that more accurately considers the dura tion component

of the acute ca dmium criterion (see Section A). Population models run using 14

- hour and 1

- hour toxicity data resulted

in no life history models showing significant differences between the lambdas for control popul ations and those

exposed to the acute cadmium criterion magnitude

. W hen the appropriate duration aspect of the criterion is

incorporated in the model runs, there are n o population

- level risks. Therefore, E PA concludes RPA step 5 is

met.

17

### Table 3. 96

- Hour Acute Juvenile Salmonid Toxicity Data Sources for Population Model Analysis

Study Species (common) Test Description Hardness (mg/L) Dissolved? Notes

Besser et al. 2007 Rainbow trout Acute 2 103 yes

Acute 4 103 yes

Brinkman 2012 Rio Grande cutthroat trout 44.9 yes

Davies et al. 1993 1,2 Rainbow trout Acute 1

- 200H, 30

alk see notes no Hardness differed for individual conc., was

normalized prior to regression. Hardness

>50 from a Mg salt, not a Ca salt. Source

water hardness = 45 mg/L.

Acute 2

- 200H, 30

alk see notes no Hardness differed for individual conc., was

normalized prior to regression. Hardness

>50 from a Mg salt, not a Ca salt. Source

water hardness = 45 mg/L.

Acute 1

- 50H, 30 alk see notes no Hardness differed for individual conc., was

normalized prior to regression. Hardness

>50 from a Mg salt, not a Ca salt. Source

water hardness = 45 mg/L.

Acute 2

- 50H, 30 alk see notes no Hardness differed for individual conc., was

normalized prior to regression. Hardness

>50 from a Mg salt, not a Ca salt. Source

water hardness = 45 mg/L.

Davies and Brinkman

1994b Rainbow trout Acute 1

- unaged hard 281 yes

Acute 2

- unaged hard 281 yes

Acute 1

- aged hard 258 yes Retained, but flagged due to uncertainty of

response between 2 highest conc.

Acute 2

- aged hard 276 yes

Acute 1

- unaged soft 29 yes

Acute 2

- unaged soft 28 yes

Phipps and Holcombe

1985 Rainbow trout 44.4 no

Stratus Consulting 1999 Bull trout Bank 1

- Bull, H30.7,

pH 7.5, 9901 30.7 no

Bank 2

- Bull, H89.3,

pH 7.54, 9901 89.3 no

Bank 3

- Bull, H30,

pH 6.65, 9901 30 no

Bank 3

- Bull, H29.3,

pH 7.56, 9905 29.3 no

Bank 2

- Bull, H31.7,

pH 7.58, 9908 31.7 no

Bank 3

- Bull, H30.2,

pH 7.57, 9908 30.2 no

Rainbow trout Bank 1

- RBT, H30.7,

pH 7.51, 9901 30.7 no

Bank 2

- RBT, H89.3,

pH 7.52, 9901 89.3 no

Bank 3

- RBT, H30,

pH 6.66, 9901 30 no

Bank 3

- RBT, H29.3,

pH 7.39, 9905 29.3 no

Bank 2

- RBT, H31.7,

pH 7.43, 9908 31.7 no

Bank 3

- RBT, H30.2,

pH 7.42, 9908 30.2 no

18

### Table 4. Population Model Analysis Results

Geometric Mean 96

- Hour LC 50 (0

- 10g salmonids)

Parameter Value Output Control Exposed

Chemical Cd % change lambda

- - 1

Concentration 1.8 % chg l std

- 12.7

LC50 3.572 lambda mean 1.09 1.08

LC50 slope 4.978 lambda std 0.1 0.1

species chinook, ot S1 5.64E

- 03 5.46E

- 03

% Mortality 3 Significant change 9.1

Percent Exposed 100

Chemical Cd % change lambda

- - 1

Concentration 1.8 % chg l std

- 4.3

LC50 3.572 lambda mean 1 0.99

LC50 slope 4.978 lambda std 0.03 0.03

species chinook, st S1 6.44E

- 02 6.22E

- 02

% Mortality 3 Significant change 3.1

Percent Exposed 100

Chemical Cd % change lambda

- - 1

Concentration 1.8 % chg l std

- 7.9

LC50 3.572 lambda mean 1.01 1

LC50 slope 4.978 lambda std 0.06 0.06

species sockeye S1 2.57E

- 02 2.49E

- 02

% Mortality 3 Significant change 5.6

Percent Exposed 100

Chemical Cd % change lambda

- - 1

Concentration 1.8 % chg l std

- 7.4

LC50 3.572 lambda mean 1.03 1.02

LC50 slope 4.978 lambda std 0.05 0.05

species coho S1 2.97E

- 02 2.87E

- 02

% Mortality 3 Significant change 5.3

Percent Exposed 100

96

- Hour Lowest Species Mean Value (0

- 10g; rainbow trout )

Parameter Value Output Control Exposed

Chemical Cd % change lambda

- - 1

Concentration 1.8 % chg l std

- 12.7

LC50 3.36 lambda mean 1.09 1.07

LC50 slope 4.562 lambda std 0.1 0.1

species chinook, ot S1 5.64E

- 03 5.33E

- 03

% Mortality 5 Significant change 9.1

Percent Exposed 100

Chemical Cd % change lambda

- - 1

Concentration 1.8 % chg l std

- 4.3

LC50 3.36 lambda mean 1 0.99

LC50 slope 4.562 lambda std 0.03 0.03

19species chinook, st S1 6.43E

- 02 6.08E

- 02

% Mortality 5 Significant change 3.1

Percent Exposed 100

Chemical Cd % change lambda

- - 1

Concentration 1.8 % chg l std

- 7.8

LC50 3.36 lambda mean 1.01 1

LC50 slope 4.562 lambda std 0.06 0.06

species sockeye S1 2.58E

- 02 2.43E

- 02

% Mortality 5 Significant change 5.6

Percent Exposed 100

Chemical Cd % change lambda

- - 2

Concentration 1.8 % chg l std

- 7.3

LC50 3.36 lambda mean 1.03 1.01

LC50 slope 4.562 lambda std 0.05 0.05

species coho S1 2.97E

- 02 2.80E

- 02

% Mortality 5 Significant change 5.3

Percent Exposed 100

14

- Hour LC 50 ( rainbow trout )

Parameter Value Output Control Exposed

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 12.9

LC50 13.767 lambda mean 1.09 1.09

LC50 slope 4.131 lambda std 0.1 0.1

species chinook, ot S1 5.62E

- 03 5.64E

- 03

% Mortality 0 Significant change 9.1

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 4.4

LC50 13.767 lambda mean 1 1

LC50 slope 4.131 lambda std 0.03 0.03

species chinook, st S1 6.44E

- 02 6.44E

- 02

% Mortality 0 Significant change 3.1

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 7.9

LC50 13.767 lambda mean 1.01 1.01

LC50 slope 4.131 lambda std 0.06 0.06

species sockeye S1 2.56E

- 02 2.57E

- 02

% Mortality 0 Significant change 5.6

20Percent Exposed 100

Chemical Cd % change lambda

- - 0

Concentration 1.8 % chg l std

- 7.5

LC50 13.767 lambda mean 1.03 1.03

LC50 slope 4.131 lambda std 0.05 0.05

species coho S1 2.97E

- 02 2.96E

- 02

% Mortality 0 Significant change 5.3

Percent Exposed 100

14

- h ou r LC 50 ( bull trout )

Parameter Value Output Control Exposed

Chemical Cd % change lambda

- - 0

Concentration 1.8 % chg l std

- 12.8

LC50 40.198 lambda mean 1.09 1.09

LC50 slope 9.47 lambda std 0.1 0.1

species chinook, ot S1 5.65E

- 03 5.64E

- 03

% Mortality 0 Significant change 9.1

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 4.4

LC50 40.198 lambda mean 1 1

LC50 slope 9.47 lambda std 0.03 0.03

species chinook, st S1 6.43E

- 02 6.44E

- 02

% Mortality 0 Significant change 3.1

Percent Exposed 100

Chemical Cd % change lambda

- - 0

Concentration 1.8 % chg l std

- 7.9

LC50 40.198 lambda mean 1.01 1.01

LC50 slope 9.47 lambda std 0.06 0.06

species sockeye S1 2.58E

- 02 2.57E

- 02

% Mortality 0 Significant change 5.6

Percent Exposed 100

Chemical Cd % change lambda

- - 0

Concentration 1.8 % chg l std

- 7.5

LC50 40.198 lambda mean 1.03 1.03

LC50 slope 9.47 lambda std 0.05 0.05

species coho S1 2.97E

- 02 2.97E

- 02

% Mortality 0 Significant change 5.3

Percent Exposed 100

211

- Hour LC 50 (rainbow trout)

Parameter Value Output Control Exposed

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 12.9

LC50 18.85 lambda mean 1.09 1.09

LC50 slope 4.131 lambda std 0.1 0.1

species chinook, ot S1 5.62E

- 03 5.64E

- 03

% Mortality 0 Significant change 9.1

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 4.4

LC50 18.85 lambda mean 1 1

LC50 slope 4.131 lambda std 0.03 0.03

species chinook, st S1 6.44E

- 02 6.44E

- 02

% Mortality 0 Significant change 3.1

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 7.9

LC50 18.85 lambda mean 1.01 1.01

LC50 slope 4.131 lambda std 0.06 0.06

species sockeye S1 2.56E

- 02 2.57E

- 02

% Mortality 0 Significant change 5.6

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 7.5

LC50 18.85 lambda mean 1.03 1.03

LC50 slope 4.131 lambda std 0.05 0.05

species coho S1 2.97E

- 02 2.97E

- 02

% Mortality 0 Significant change 5.3

Percent Exposed 100

1

- hour LC 50 (bull trout)

Parameter Value Output Control Exposed

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 12.9

LC50 66.878 lambda mean 1.09 1.09

LC50 slope 9.47 lambda std 0.1 0.1

species chinook, ot S1 5.62E

- 03 5.64E

- 03

% Mortality 0 Significant change 9.1

22Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 4.4

LC50 66.878 lambda mean 1 1

LC50 slope 9.47 lambda std 0.03 0.03

species chinook, st S1 6.43E

- 02 6.43E

- 02

% Mortality 0 Significant change 3.1

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 7.9

LC50 66.878 lambda mean 1.01 1.01

LC50 slope 9.47 lambda std 0.06 0.06

species sockeye S1 2.57E

- 02 2.57E

- 02

% Mortality 0 Significant change 5.7

Percent Exposed 100

Chemical Cd % change lambda

- 0

Concentration 1.8 % chg l std

- 7.5

LC50 66.878 lambda mean 1.03 1.03

LC50 slope 9.47 lambda std 0.05 0.05

species coho S1 2.97E

- 02 2.97E

- 02

% Mortality 0 Significant change 5.3

Percent Exposed 100

23

### Figure 1. Histograms summarizing individual model iterations of the control and exposed scenarios for

the chinook ocean

- type life history model. X axis indicates lambda estimate while Y axis indicates the

number of iterations (counts) for each unique lambda estimate. Blue bars indicate control population

( chinookot

c 

### ) iterations; yellow bars indicate exposed population ( chinookot

e 

### ) iterations

. Gree n indicates

o verlap between two histograms. Data used to generate figure were from the population model using the

geometric mean of 96 hour toxicity data for 0

- 10 g salmonid fish es as input (Table 4).



## II. SUMMARY OF ACUTE RPA RESPONSE ANALYSIS

The available toxicity data set for cadmium was relatively large compared to other pollutants. As a result, EPA

was able to perform RPA steps 1

- 5 using quality data which would be considered acceptable for 304(a) water

quality criteria derivation. The EPA followed the p rocess outlined in RPA steps 1

- 3 in the NMFS 2012

biological opinion to estimate a minimum effects threshold (e.g., LC 5 

### or LC 10 

### ) for cadmium. EPA identified 29

acute cadmium toxicity tests from seven salmonid studies that contained sufficient quality data to generate a C

R curve and calculate minimum effect thresholds. Twenty

- eight studies (i.e., those without technical or

statistical errors) were specifically used to calculate minimum effect thresholds. The salmonid

- specific

minimum effect thresholds are 2 .06 μg/L (LC 10 

### , dissolved Cd , hardness = 100 mg/L) and 1.79 μg/L (LC 05



### , dissolved Cd , hardness = 100 mg/L). Because the acute cadmium criterion magnitude for Oregon is equal to the

salmonid minimum effects threshold (LC 05 

### ) that NMFS specified EPA use in deriving the acute cadmium

criterion, EPA co ncludes that RPA steps 1

- 3 are met . Furthermore, the mixtures analysis suggest s that metal

mixtures in freshwaters will not result in toxic effects to salmonids, eulachon, and green sturgeon greater than

the asse ssment effect concentrations. As a result, EPA also concludes that RPA step 4 is met

.

24

### Population model (based on 96 hour LC 50 

### values) output demonstrated that cadmium

- exposed population

lambda values never differed from control population lambda values by more than one standard deviation of the

control lambda distribution. As a result, the population model did not detect significant differences in

population

- level effects of cadmium between control (i.e., unexposed to cadmium) and exposed salmonid

populati ons. Additionally, EPA used the population model with inputs that are consistent with the magnitude

and duration components of the acute cadmium criterion and found no change in the intrinsic growth. 7



### Therefore, EPA considers RPA step 5 to be met.

This RPA analysis demonstrates that the acute aquatic life cadmium criterion the EPA is proposing to

promulgate in Oregon is consistent with the intent of the RPA and avoids jeopardizing Endangered Species Act

threatened and endangered species or adversely modi fying their designated critical habitat.

7 EPA is currently underg oing analyses to explore potential methods for accurately considering excursion fr equency in the population

model

.

25

## Appendix A

Reasonable and Prudent Alternatives for Cadmium

Acute. The EPA shall disapprove the State of Oregon’s acute crite rion of 2.0 μ g/L at 100 mg/L Ca CO 3 

### for

freshwater cadmium. The EPA shall use the Process for Deriving Criteria, specified below, to derive an acute

criterion for the State of Oregon for freshwater cadmium. The EPA shall recommend that the State adopt, and

EPA will promulgate if necessary, the derived acute cadmium criterion. The EPA will ensure that the derived

acute ammonia, cadmium or aluminum criteri a will be effective within 24 months after EPA’s final action to

approve or disapprove Oregon’s proposed water quality criteria under the CW A.

Process for Deriving Criteria (pages 550

– 551 of the NMFS 2012 biological o pinion ) :

The EPA shall use the process for deriving criteria, specified below, to set an acute criterion for

freshwater cadmium

.

The EPA shall utilize analytical methods that meet NMFS

- specified requirements to derive numeric

criteria for aquatic life, taking into account the same factors considered by NMFS in completing its

analysis for the other criteria in this opinion. In particular, the EPA shall derive criteria for acute

ammonia, acute cadmium, and acute and chronic aluminum in compliance with the following five

requirements:

1) Only use toxicity data for ammonia, cadmium, and aluminum that is specific to salmonid fishes (if

new information becomes available for these compounds for green sturgeon and eulachon, then

EPA shall include this data in its analysis);

2) All toxicity data used to derive the numeric criteria must be curve

- fitted, where the literature

provides the necessary data to perform this step;

3) When available, the curve

- fitted toxicity data must be used to extrapolate threshold acute and

chronic toxic effect concentrations;

4) Derived criteria must be model

- adjusted to account for chemical mixtures; and

5) An appropriate population model must be applied to the derived criteria, and must predict no

negative change in the intrinsic population growth rate (e.g., lambda).

More specifically, EPA shall ensure that the derived criteria are developed in compliance with the

following mandatory sideboards:

• The EPA shall use toxicity data specific to salmonid fishes. The EPA shall use the acute and chronic

toxicity data in this opinion as a minimum data set. For green sturgeon and eulachon, EPA shall use the

salmonid fishes [ sic ] toxicity data for this analysis, as described in section 2.6.2 in this opinion, in

addition to any new data that becomes available for green sturgeon and eulachon.

• The EPA shall use toxicity data based on exposure

- response curves and fixed duration toxicity tests to

estimate acute and chronic toxic effect thresholds to assess effects on multiple life stages and multiple

endpoints, to include at a minimum: mortality, latent mortality, reproduction, growth, physiological, cellular,

behavioral, and biochemical effects, where the data exists. The EPA may use existing toxicity data for

26

### ammonia , cadmium or aluminum

... or generate new data, but the data shall be curve

- fitted (see Figure

2.6.1.1) to determine the minimum effect thresholds (e.g., 5%) at which acute and chronic toxic effects are

predicted.

• 

### The EPA shall ensure that each derived criterion for ammonia, cadmium, and aluminum is adjusted to

account for chemical mixtures using a concentration

– addition model or response

- addition model to

determine whether or not exposure to multiple compounds will result in additive effects to the listed species

considered in this opinion. The concentration

– addition model or response

- addition model shall include all

compounds listed in Table 1.1. If the mixture effects prediction is greater than one, EPA shall adjust the

concentrations for ammonia, cadmium, and aluminum until the mixture effects prediction is less than one.

• 

### The EPA shall ensure that the derived criteria for ammonia, cadmium, and aluminum do not result in a

negative change in the intrinsic population growth rate based on the geometric mean abundance data for each

life history type, i.e

., coho salmon ( O. kisutch ), sockeye salmon ( O. nerka ) and ocean

- type and stream

- type

Chinook salmon ( O. tshawytscha ), of salmonid fish considered in this opinion, at the population scale. The

EPA shall use stream

- type Chinook salmon as a surrogate for steelhead, and ocean

- type Chinook salmon as a

surrogate for chum salmon in the population model, as described in section 2.6.5.1 of this opinion. Pacific

salmon and steelhead abundance data is available from the Northwest Fisheries Science Center Salmon

Population Summary Database 8



### or from the Columbia Basin Fish and Wildlife Authority Status of the Fish and

Wildlife Resources Database 9



### . The abundance data used for the population growth rate analysis shall include

data from all years with available abundance data. For green sturgeon and eulachon, EPA shall use the

salmonid fishes toxicity data and modeling results as surrogate data and outputs for this analysis.

• 

### To ensure that the derived numeric criteria for ammonia, cadmium, and aluminum meet the population

growth rate condition of the RPA, EPA shall run the criteria for ammonia, cadmium, and aluminum through a

population model ( e.g.

, Leslie Matrix), parameterized for Pacific salmonid fishes. Model requirements

include: (1) scenarios based on change in first year survival; (2) an assumption that the populations are

density

- independent, to reduce the probability of Type II errors; (3) sigmoid slopes are generated from the

data used to derive the numeric criteria, and if a slope cannot be generated from the data, EPA shall use the

default sigmoid slope of 3.6 used in this opinion; and (4) exposure

- response scenarios using the geometric

mean of the curve

- fitted data, and the minimum species mean value of the curve

- fitted data, and the

minimum species mean value of the curve

- fitted data, from the toxicity data used to derive the numeric

criteria.

8 https:// www.webapps.nwfsc.noaa.gov/sps

9 http;//sort.cbfwa.org

27