oEPA
United States
Environmental Protection
Agency
Region 9 & Office of Water
EPA-822-R-24-014
December 2024
FINAL
Aquatic Life and Aquatic-Dependent
Wildlife Selenium Water Quality Criterion
for Freshwaters of California
December 2024
U.S. Environmental Protection Agency
Office of Water
Office of Science and Technology
Washington, D.C.
U.S. Environmental Protection Agency Region 9
Water Division
San Francisco, CA
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Table of Contents
Table of Contents ii
List of Tables iv
List of Figures vi
Executive Summary x
Part 1 Introduction and Background 1
1.1 Early Selenium Efforts 1
1.2 California Toxics Rule 4
Part 2 Problem Formulation 6
2.1 Overview of Selenium Sources and Occurrence in California 6
2.2 Selenium Speciation in Aquatic Systems 13
2.3 Bioaccumulation of Selenium in Aquatic Systems 16
2.4 Effects and Biota 18
2.4.1 Mode of Action and Toxicity of Selenium 18
2.4.2 Narrow Margin between Sufficiency and Toxicity of Selenium 19
2.4.3 Adverse Effects of Selenium in Fish and Birds 20
2.5 Assessment Endpoints 23
2.6 Measures of Ecological Effect 23
2.7 Selenium Effects Concentrations in Fish Tissues and Bird Eggs 24
2.7.1 Water 26
2.7.2 Summary of Assessment Endpoints and Measures of Effect 27
2.7.3 Conceptual Model of Selenium Effects on Aquatic Life and Aquatic-Dependent
Wildlife 28
Part 3 Effects Analysis for Freshwater Aquatic Organisms 30
3.1 Purpose 30
3.2 Overview of Effects Analysis for Freshwater Aquatic Organisms 30
3.2.1 Fish Egg-Ovary Criterion Element Concentration 34
3.2.2 Fish Whole Body Criterion Element Concentration 34
3.2.3 Fish Muscle Criterion Element Concentration 35
Part 4 Effects Analysis for Aquatic-Dependent Wildlife 36
4.1 Purpose 36
4.2 Chronic Toxicity to Aquatic-Dependent Wildlife 36
4.2.1 Summary of Selenium Reproductive Toxicity Studies Used to Derive the Aquatic-
Dependent Wildlife Criterion 38
4.3 Derivation of Bird Egg Criterion Element 43
4.4 Previously Calculated Selenium Thresholds (as ECio) for Mallard Hatchability 45
4.5 Chronic Egg Selenium Criterion Element Concentration 52
4.6 Summary of Selenium Toxicology Studies Used Qualitatively in the Criterion
Derivation 53
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4.6.1 Reproductive Studies Used Qualitatively in the Criterion Derivation 53
4.6.2 Non-Reproductive Studies Used Qualitatively in the Criterion Derivation 64
Part 5 Method Used to Translate the Bird Egg and Fish Tissue Criterion Elements
into Water Column Elements 70
5.1 Purpose 70
5.2 Translation from Tissue Concentration to Water Column Concentration Using the
Mechanistic Model 70
5.3 Equation Parameters 72
5.3.1 Derivation of Trophic Transfer Factor (TTF) Values 72
5.3.2 Derivation of Egg-Ovary to Whole Body Conversion Factor (CF) Values for
Aquatic Life 80
5.3.3 Calculation of Site-Specific Enrichment Factor (EF) Values 82
5.4 Food Web Models 84
5.4.1 Aquatic Life 84
5.4.2 Aquatic-Dependent Wildlife 84
5.5 Deriving National Protective Water Column Concentrations for Lentic and Lotic
Systems 87
5.5.1 Aquatic Life 87
5.5.2 Aquatic-Dependent Wildlife 94
5.6 Derivation of Averaging Period for Chronic Water Criterion Element and
Intermittent-Exposure Water Criterion Element 102
Part 6 Aquatic and Aquatic-dependent wildlife Criteria for Selenium in
California's Fresh Waters 104
6.1 Protection of Downstream Waters 108
6.2 Site-specific Criteria 108
References 110
Appendix A Summary Information for Quantitative and Qualitative Bird
Studies A-l
Appendix B Calculation of Trophic Transfer Factors B-1
Appendix C Total Selenium and Dissolved Selenium Concentrations in
California Water Bodies C-l
Appendix D Comparison of Measured and Paired Bird and Fish Tissue Selenium
Concentrations Relative to Their Respective Tissue Criteria D-l
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List of Tables
Table 1-1. Summary of the Final California Selenium Ambient Chronic Water Quality
Criteria for Protection of Aquatic Life and Aquatic-Dependent Wildlife xii
Table 2-1. Predominant Chemical Forms of Selenium in Discharges Associated with
Different Activities and Industries 15
Table 2-2. Summary of Assessment Endpoints and Measures of Effect Used in Criteria
Derivation for Selenium 28
Table 3-1. Maternal Transfer Reproductive Toxicity Studies 32
Table 3-2. Four Lowest Genus Mean Chronic Values for Fish Reproductive Effects
(U.S. EPA 2016a) 34
Table 3-3. The Lowest Four Reproductive-Effect Whole Body GMCVs 35
Table 3-4. The Lowest Four Reproductive-Effect Fish Muscle GMCVs 35
Table 4-1. Effect of Dietary Selenium (as Selenomethionine) on Hatchability of Mallard Eggs
and the Associated Concentration of Selenium in Eggs 42
Table 4-2. Previously Calculated and Current Selenium ECio values for Mallard Hatchability.. 51
Table 5-1. EPA-Derived Trophic Transfer Factor ('/IT') Values for Freshwater Aquatic
Invertebrates (U.S. EPA 2016a) 78
Table 5-2. EPA-Derived Trophic Transfer Factor (TTF) Values for Freshwater Fish
(U.S. EPA 2016a) 78
Table 5-3. EPA-Derived Trophic Transfer Factor (TTF) Values for Aquatic-Dependent Birds.. 79
Table 5-4. EPA-Derived Egg-Ovary to Whole Body Conversion Factor (CF) Values
(U.S. EPA 2016a) 81
Table 5-5. EPA-Derived Composite Selenium Trophic Transfer Factors (TTFcomposite) for
Aquatic-Dependent Birds 86
Table 5-6. Composite Selenium Trophic Transfer Factors (TTFcomposite) for Aquatic-Dependent
Bird Species of Concern in California 87
Table 5-7. Data for the 65 Site Minimum Translations of the Fish Egg-Ovary Criterion
Concentration Element to a Water Column Concentration (U.S. EPA 2016a) 89
Table 5-8. Water Column Criterion Element Concentration Values Translated from the Fish
Egg-Ovary Criterion Element in the 2016 National Selenium Aquatic Life Criterion
(U.S. EPA 2016a) 93
Table 5-9. Data for the 65 Site Minimum Translations of the Bird Egg Criterion Concentration
Element to a Water Column Concentration 96
Table 5-10. Water Column Concentration Values Translated from the Bird Egg Criterion
Element Using the 26 Lentic and 39 Lotic Sites in the National Selenium Aquatic
Life Criterion (U.S. EPA 2016a) 101
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Table 5-11. Comparison of 20th Percentile Water Column Concentration Values (|ig/L)
Translated from the Fish Egg-Ovary Criterion Element and the Bird Egg Criterion
Element for the 26 Lentic and 39 Lotic Sites from the 2016 Aquatic Life Criteria
(ALC) Dataset and the 65 Sites from the ALC Dataset + 5 Additional California
Sites (4 Lentic and 1 Lotic) 101
Table 6-1. Summary of the Final California Selenium Ambient Chronic Water Quality
Criteria for Protection of Aquatic Life and Aquatic-Dependent Wildlife 105
Table A-l. Quantitative aquatic-dependent wildlife toxicity data considered and used for
criterion development A-2
Table A-2. Qualitative aquatic-dependent wildlife toxicity reproductive data considered for
criterion development A-3
Table A-3. Qualitative aquatic-dependent wildlife toxicity non-reproductive data considered
for criterion development A-8
Table B-l. American Avocet Trophic Transfer Factor (TTF) B-3
Table B-2. American Coot Trophic Transfer Factor (TTF) B-7
Table B-3. Cinnamon Teal Trophic Transfer Factor (TTF) B-l 1
Table B-4. Eared Grebe Trophic Transfer Factor (TTF) B-12
Table B-5. Gadwall Trophic Transfer Factor (TTF) B-16
Table B-6. Pied-Billed Grebe. Bird Egg to Fish (TTF) B-19
Table B-7. Red-Winged Blackbird Trophic Transfer Factor (TTF) B-20
Table B-8. Yellow-Headed Blackbird Trophic Transfer Factor (TTF) B-22
Table B-9. Ridgway's Rail Trophic Transfer Factor (TTF) after Reweighting Surrogate
Species American Coot Diet to a 15% Plant and 85% Animal Diet B-32
Table B-10. Black Rail Trophic Transfer Factor (TTF) after Reweighting Surrogate Species
American Coot Diet to a 13% Plant and 87% Animal Diet B-36
Table B-l 1. Light-Footed Ridgeway's Rail and Yuma Rail Trophic Transfer Factor (TTF)
after Reweighting Surrogate Species American Coot Diet to a 100% Animal Diet. B-40
Table B-12. American Dipper. Bird Egg to Diet (TTF) after Reweighting Surrogate Species
Red-Winged Blackbird to a 100% Animal Diet B-45
Table B-13. American Dipper. Bird Egg to Diet (TTF) after Reweighting Surrogate Species
Yellow-Headed Blackbird to a 100% Animal Diet B-47
Table B-14. Fish jjpcomP°site for the 32 species with empirically derived TTF B-58
Table C-l. Total Selenium Concentrations in California Water Bodies C-l
Table C-2. Dissolved Selenium Concentrations in California Water Bodies C-9
Table C-3. Total Selenium Concentrations by Regional Board Area C-l8
Table C-4. Dissolved Selenium Concentrations by Regional Board Area C-19
Table D-l. Counts and Relative Proportions of Whether Paired Selenium Measurements in
Bird Eggs and Fish Whole-Body or Egg-Ovary Tissues Met or Exceeded Their
Respective Criterion D-5
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Table D-2. Bird and Fish Tissue Species Level Average Selenium Concentrations
(mg Se/kg dw) D-10
List of Figures
Figure 2-1. Areas of California with seleniferous marine geology 8
Figure 2-2. Areas of California susceptible to selenium contamination (gray) and where
agricultural land is irrigated (green) 10
Figure 2-3. Distributions and abundances of total selenium concentrations (|ig/L) in surface
water samples collected from October 5, 2004 through June 3, 2014 12
Figure 2-4. Conceptual model diagram of sources, compartmental partitioning, and trophic
transfer pathways of selenium in the aquatic environment and bioaccumulation and
effects in aquatic-dependent wildlife 29
Figure 4-1. Logistic regression model of mallard hatchability in relation to egg selenium
concentrations 45
Figure 4-2. Mallard egg hatchability as a function of selenium concentration in eggs 46
Figure 4-3. Mallard egg hatchability in the six studies, fitted using a tolerance distribution
model, without normalization to control values. Source is Figure 2 in U.S. EPA
(201 la). Confidence intervals surrounding the ECio were not included in the source
document 47
Figure 4-4. Mallard percent hatch v. egg concentration for six studies values 49
Figure 5-1. Example aquatic system scenarios and the derivation of the equation parameter
YYpcomposite
Figure 5-2. Probability distribution of the water column concentrations translated from the
fish egg-ovary criterion element at 26 lentic and 39 lotic aquatic sites
(U.S. EPA 2016a) 93
Figure 5-3. Probability distribution of the water column concentrations translated from the
bird egg criterion element at the 26 lentic and 39 lotic aquatic sites from
U.S. EPA (2016a) 100
Figure C-l. Distributions and abundances of total selenium concentrations (|ig/L) in surface
water samples collected from October 5, 2004 through June 3, 2014 C-16
Figure C-2. Distributions and abundances of dissolved selenium concentrations (|ig/L) in
surface water samples collected from October 5, 2004 through June 3, 2014 C-17
Figure D-l. Selenium concentrations in paired bird egg and fish whole body tissue samples
throughout the Western U.S D-3
Figure D-2. Selenium concentrations in paired bird egg and fish egg-ovary tissue samples
throughout the Western U.S D-4
Figure D-3. Selenium concentrations in paired bird egg and fish whole body tissue samples
from lentic sites throughout the Western U.S D-6
Figure D-4. Selenium concentrations in paired bird egg and fish egg-ovary tissue samples
from lentic sites throughout the Western U.S D-7
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Figure D-5. Selenium concentrations in paired bird egg and fish whole body tissue samples
from lotic sites throughout the Western U.S D-8
Figure D-6. Selenium concentrations in paired bird egg and fish egg-ovary tissue samples
from lotic sites throughout the Western U.S D-9
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Acknowledgements
Technical Analysis Leads
Amanda Jarvis, U.S. EPA, Office of Water, Office of Science and Technology, Health and
Ecological Criteria Division, Washington, DC (primary contact), iarvis.amanda@epa.gov
Julie McLaughlin, Ph.D., (formerly in) U.S. EPA, Office of Water, Office of Science and
Technology, Standards and Health Protection Division, Washington, DC.
Daniel R. Oros, Ph.D. (retired from EPA in 2019), U.S. EPA Region 9, Water Quality
Assessment Office, Water Division; Ecosystem Branch, San Francisco, California.
U.S. EPA Office of Water Reviewers
Joseph Beaman
Colleen Flaherty
Kathryn Gallagher
Karen Kesler
EPA Peer Reviewers
Diane Fleck, U.S. EPA Region 9, San Francisco, CA
Karen Kessler, U.S. EPA, Office of Water, Office of Science and Technology, Standards and
Health Protection Division, Washington, DC
Jim Lazorchak, U.S. EPA, Office of Research and Development, National Exposure Research
Laboratory, Cincinnati, OH
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Acronyms
AE
Assimilation Efficiency
ALC
Aquatic Life Criteria
AWQC
Ambient Water Quality Criteria
BAF
Bioaccumulation Factor
CF
Conversion Factor
CFR
Code of Federal Regulations
CTR
California Toxics Rule
CWA
Clean Water Act
dw
Dry Weight
ECx
Effect Concentration at X Percent Effect Level
EF
Enrichment Factor
ESA
Endangered Species Act
EO
Egg-Ovary
FCV
Final Chronic Value
FR
Federal Register
fww
Fresh Wet Weight
GMCV
Genus Mean Chronic Value
GSD
Genus Sensitivity Distribution
IR
Ingestion Rate
ke
Rate of selenium loss
LCL
Lower Confidence Limit
LOEC
Lowest Observed Effect Concentration
M
Muscle
MATC
Maximum Acceptable Toxicant Concentration (expressed mathematically as the
geometric mean of the NOEC and LOEC)
NTR
National Toxics Rule
NPDES
National Pollutant Discharge Elimination System
NOEC
No Observed Effect Concentration
OLS
Ordinary Least Squares
SMCV
Species Mean Chronic Value
T&E
Threatened and Endangered
TMDL
Total Maximum Daily Load
TRAP
EPA's Statistical Program: Toxicity Relationship Analysis Program
TSD
Technical Support Document
TTF
Trophic Transfer Factor
UCL
Upper Confidence Limit
WB
Whole body
WQBELS
Water Quality-based Effluent Limitations
WQC
Water Quality Criteria
WQS
Water Quality Standards
WW
Wet Weight
IX
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Executive Summary
This document sets forth the U.S. Environmental Protection Agency's (EPA) basis for
and derivation of the final selenium water quality criterion for the inland surface waters,
enclosed bays, and estuaries of California to protect aquatic life and aquatic-dependent wildlife,
including federally listed threatened and endangered species. This assessment relies on the
EPA's Section 304(a) Aquatic Life Ambient Water Quality Criterion for Selenium - Freshwater
2016 for the aquatic life portion of the criteria (U.S. EPA 2016a). In addition, this assessment
provides a critical review of all data identified in the EPA's literature search quantifying the
toxicity of selenium to aquatic-dependent wildlife and provides a basis for a criterion that will
assure protection of aquatic-dependent wildlife species found in California from the chronic
toxic effects of selenium.
The EPA previously derived freshwater selenium aquatic life chronic tissue-based
criterion elements for egg-ovary, whole body and/or muscle concentrations in fish, and translated
the tissue-based criterion elements into freshwater selenium water column criterion elements for
aquatic life (U.S. EPA 2016a), both of which are summarized in this document. The aquatic-
dependent wildlife chronic tissue-based criterion element for bird eggs was not part of the 2016
aquatic life selenium criterion and therefore is derived herein.
The EPA utilized the translation equation from the peer-reviewed and validated
Ecosystem Scale Selenium Model (Presser and Luoma 2010) to independently derive protective
selenium concentrations in the water column based on bird egg criterion element concentration.
This mechanistic model approach is also the basis for the Performance Based Approach (PBA)
discussed in Methodfor Translating Selenium Tissue Criterion Elements into Site-specific Water
Column Criterion Elements for California, Version 2 December 2024 (EPA document number:
820-R-24-008; U.S. EPA 2024a), which can be used to derive site-specific protective selenium
concentrations in the water column from the fish tissue and bird egg criterion element
concentration in California. This mechanistic approach previously used for estimating protective
selenium concentrations in the water column from fish egg-ovary criterion concentrations (U.S.
EPA 2016a) is summarized in Part 5 of the present document. The translation equation uses
species-specific food web models, species-specific bioaccumulation parameters (conversion
factor (CF) and trophic transfer factors (TTF)), and a site-specific selenium enrichment factor
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(EF), which describes the enrichment of selenium concentrations from water to particulate
matter (plankton, detritus, and sediment), to calculate a site-specific water column concentration
element from the fish egg-ovary and bird egg criterion elements. All modeling incorporated site-
specific ecosystem variables (e.g., fish or bird species, EFs, and water body type) on a national
scale to calculate selenium water column-based criterion elements for lentic and lotic freshwater
systems and an intermittent water column-based criterion element that are appropriate for
California. In this analysis, the EPA found that the selenium water column-based criterion
elements previously derived by the EPA (U.S. EPA 2016a) to protect aquatic life are also
protective of aquatic-dependent wildlife, based on an independent analysis of the aquatic-
dependent wildlife data. These tissue-based and default water column criterion element
concentrations were developed to protect aquatic life and aquatic-dependent wildlife from
reproductive effects associated with dietary exposure and maternal transfer to eggs resulting in
mortality, teratogenicity, and decreased hatchability. The available data and modeling results
demonstrate that aquatic life and aquatic-dependent wildlife are expected to be protected from
the toxic effects of selenium in California by applying the following multi-element criterion:
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Table 1-1. Summary of the Final California Selenium Ambient Chronic Water Quality
Criteria for Protection of Aquatic Life and Aquatic-Dependent Wildlife.
Media
Type
Bird Tissue
Fish Tissue1
Water Column4
Criterion
Element
Bird Egg2
Egg-Ovary2
Fish Whole-
Body or
Muscle3
Monthly
Average
Exposure5
Intermittent Exposure6
8.5 mg/kg dw
whole-body
1.5 (ig/L in lentic
aquatic systems
Magnitude
11.2 mg/kg
dw
15.1 mg/kg dw
or
11.3 mg/kg dw
muscle
(skinless,
boneless filet)
3.1 (ig/L in lotic
aquatic systems
WQCint =
WQCzo-day CbkgrndQ fint)
f int
Duration
Instantaneous
measurement7
Instantaneous
measurement7
Instantaneous
measurement7
30 days
Number of days/month with an
elevated concentration
Frequency
Not to be
exceeded
Not to be
exceeded
Not to be
exceeded
Not more than
once in three
years on average
Not more than once in three years
on average
1. Fish tissue criterion elements are expressed as steady-state.
2. Fish egg-ovary supersedes any whole-body, muscle, or water column criterion elements for aquatic life when fish egg-ovaries are measured,
except as noted in footnote 4. Bird egg supersedes water column criterion elements for aquatic-dependent wildlife when bird eggs are measured,
except as noted in footnote 4. The bird tissue criterion element is independently applicable from and equivalent to the fish tissue criterion
elements.
3. Fish whole-body or muscle tissue supersedes the water column criterion elements when both fish tissue and water concentrations are measured,
except as noted in footnote 4.
4. Water column criterion elements are based on dissolved total selenium in water and are derived from fish tissue and bird tissue criterion elements
via bioaccumulation modeling. When selenium inputs are increasing, water column criterion elements are the applicable criterion elements in the
absence of steady-state condition fish tissue or bird tissue data.
5. The water column criterion element, which applies independently to the respective aquatic life and aquatic-dependent wildlife uses, is applicable
for all CWA purposes and consists of a water column value of 1.5 (ig/L in lentic aquatic systems and 3.1 (ig/L in lotic aquatic systems unless or
until a site-specific water column criterion element is derived for a particular waterbody following the methodology described in Method for
Translating Selenium Tissue Criterion Elements into Site-specific Water Column Criterion Elements for California, Version 2 December 2024.
This publication is incorporated by reference into this section with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1
CFRpart 5 1. All approved material is available at EPA, OW Docket, EPA West, Room 3334, 1301 Constitution Ave., NW, Washington, DC,
20004, (202) 566-2426. It is also available for inspection at the National Archives and Records Administration (NARA). For information on the
availability of this material at NARA, call 202-741 -6030 or go to www.archives.gov/federal-register/cfr/ibr-locations.html.
6. Where WQC30-day is the applicable water column monthly criterion element, Cbkgmd is the average background selenium concentration, and fmt is
the fraction of any 30-day period during which elevated selenium concentrations occur, with fmt assigned a value >0.033 (corresponding to 1 day).
7. Fish tissue and bird tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over time and space in
bird or fish population(s) at a given site.
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The EPA is finalizing the freshwater selenium criterion described in Table 1-1 for certain
waters in California, as provided in Section V - Applicability of the EPA Promulgated Water
Quality Standards of the final rule preamble. The EPA is finalizing the 2016 CWA section
304(a) selenium criterion for freshwater with the addition of a bird tissue criterion element, with
associated default water column criterion elements, with the addition of the ability to develop a
water column criterion element using a performance-based approach (PBA) for translating the
tissue elements into a corresponding water-column criterion element on a site-specific basis. This
approach allows for flexibility for dischargers and the State to derive site-specific water-column
criterion elements based on site-specific data, as appropriate. Available data indicate that
applying the criterion in Table 1-1 is expected to be protective of aquatic life and aquatic-
dependent wildlife from the toxic effects of selenium, recognizing that the fish tissue elements
and the bird egg element supersede any translated site-specific water column elements (except in
special situations, see footnote 4 in Table 1-1) and that the fish egg-ovary element supersedes all
other fish tissue elements. Two of the tissue criterion elements are based on the concentration of
selenium in fish tissue and one element is based on the concentration of selenium in bird eggs.
The final tissue criterion elements are: (1) a fish egg-ovary element; (2) a fish whole body and/or
muscle element; and (3) a bird egg element. The fish egg-ovary and bird egg criterion
concentrations are derived from analysis of the available selenium toxicity data for freshwater
aquatic life and aquatic-dependent wildlife species, respectively. The fish whole body and fish
muscle tissue criterion element concentrations are derived from a combination of directly
measured toxicity values and the fish egg-ovary toxicity values that have been converted using
concentration ratios among tissues. The default water column criterion lentic and lotic elements
are based on translation of the tissue criterion elements using the mechanistic Presser and Luoma
(2010) model to derive protective selenium concentrations in the water. The EPA is also
finalizing intermittent exposure water column elements for lentic and lotic waters. The PBA
consists of a methodology to allow translation of the tissue criterion elements into site-specific
water column criterion elements. The EPA is finalizing a bird tissue criterion element that is
independently applicable from and equivalent to the fish tissue elements. All tissue elements
supersede the translated water column criterion elements, either using the default or PBA water
column values, for the specific taxon when both are measured. The final selenium criterion,
expressed as a single criterion composed of multiple elements, is expected to be protective of
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aquatic life and aquatic-dependent wildlife from potential chronic effects of selenium in aquatic
ecosystems.
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Part 1 Introduction and Background
The purpose of this document is to provide the U.S. Environmental Protection Agency's
(EPA's) scientific rationale for this final selenium water quality criterion for certain waters in
California. This criterion is designed to protect aquatic life and aquatic-dependent wildlife,
including federally listed threatened and endangered species, and is based solely on the best
available data and best professional scientific judgements on the toxicological effects of
selenium in egg-laying fish and birds. This criterion was developed following the general
approach outlined in the EPA's "Guidelines for Deriving Numerical National Water Quality
Criteria for the Protection of Aquatic Organisms and Their Uses'' (Stephan et al. 1985). Pursuant
to Clean Water Act (CWA) section 303(c) and the EPA's implementing regulations at 40 CFR §
131.11(a), water quality criteria must be based on sound scientific rationale and must contain
sufficient parameters or constituents to protect designated uses. The selenium criterion for
California is intended to be protective of the State's established aquatic life and wildlife
designated uses in fresh waters which include: migration of aquatic organisms; spawning,
reproduction and early development of fish; estuarine habitat; warm and cold freshwater habitats;
wildlife habitat; and rare, threatened or endangered species. The criterion presented herein is the
EPA's best estimate of the maximum concentrations of selenium, with associated frequency and
duration specifications, that will support protection of aquatic life and aquatic-dependent wildlife
from unacceptable chronic effects in California.
The information provided herein does not substitute for the Clean Water Act or EPA
regulations, nor is this document a regulation itself. Thus, this document cannot, and does not,
impose any legally binding requirements on the EPA, the State of California, authorized Tribes,
the regulated community, or any other party.
1.1 Early Selenium Efforts
National Ambient Water Quality Criteria (AWQC) recommendations are established by
the EPA under section 304(a)(1) of the CWA. As provided for by the Clean Water Act, the EPA
reviews and from time to time revises 304(a) AWQC recommendations (CWA 304(a)
recommended criterion/a) to ensure the criteria are consistent with the latest scientific
information. Section 304(a) aquatic life criteria (ALC) serve as recommendations to states and
tribes in defining ambient water concentrations that will protect against adverse ecological
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effects to aquatic life and aquatic-dependent wildlife communities resulting from exposure to a
pollutant found in water from direct contact or ingestion of contaminated water and/or food.
Aquatic life criteria address the CWA goals of providing for the protection and propagation of
fish and shellfish. States and authorized Tribes may adopt this criterion into their water quality
standards (WQS) to protect aquatic life and aquatic-dependent wildlife designated uses. States
and authorized Tribes may also modify this criterion before adopting these into standards. After
adoption, states/authorized Tribes submit new and revised WQS to EPA for review and approval
or disapproval. When adopted into state or tribal WQS and approved by the EPA, this criterion
can become a basis for establishing National Pollutant Discharge Elimination System (NPDES)
program permit limits, listing impaired waters under Section 303(d) and establishing Total
Maximum Daily Loads (TMDLs).
In 1980, the EPA first published CWA 304(a) recommended numeric aquatic life criteria
for selenium in freshwater (acute criterion 260 |ig/L and chronic criterion 35 |ig/L, U.S. EPA
1980). These criteria were based on water-only exposure (no dietary exposure). In order to
address the lack of consideration of bioaccumulation in the 1980 selenium criteria, the EPA
published updated recommended selenium criteria in 1987 (U.S. EPA 1987) to address field-
based toxicity observed in aquatic ecosystems at concentrations below the existing criteria
values. The 1987 criteria were field-based and were based upon both the water column and
dietary uptake pathways manifested at Belew's Lake, NC, a cooling water reservoir that had
been affected by selenium loads from a coal-fired power plant. At that time, the EPA also
provided an acute criterion of 20 |ig/L derived from a reverse application of an acute-chronic
ratio obtained from conventional water-only exposure toxicity tests applied to the 5 |ig/L chronic
value based on dietary and water column exposure in Belew's Lake.
In 1998, the EPA held a peer consultation workshop to evaluate new science available for
selenium relevant to the selenium aquatic life criterion (U.S. EPA 1998). EPA concluded, and
the peer reviewers agreed, that fish tissue values better represent chronic adverse effects of
selenium than the conventional water concentration approach used by the EPA to protect aquatic
life, because chronic selenium toxicity is primarily based on the food-chain bioaccumulation
route, not a direct waterborne route. During the following years (1998-2016) and through
multiple criterion iterations, the EPA worked with technical experts to develop a final selenium
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criterion for fish tissue that would be protective of all aquatic life (See Section 1.1 of U.S. EPA
(2016a) for more details).
The EPA used the scientific principles established in a 2009 Pellston scientific workshop
on the ecological risk assessment of selenium (Chapman et al. 2009, 2010) and additional data
generated since 2009 to develop the 2014 draft recommended criterion (U.S. EPA 2014) that was
reviewed by an expert external peer review panel. In the EPA's 2016 final recommended
freshwater chronic criterion for selenium, revisions reflected consideration of the public and
external expert peer reviews of the 2014 draft, public comments on the 2015 draft, data and
information from additional studies provided by the public and peer reviewers, and additional
scientific analyses. The EPA's 2016 final recommended criterion reflected the latest scientific
consensus (e.g., Chapman et al. 2010) on the reproductive effects of selenium on aquatic life and
their measurement in aquatic systems and supersedes all previous EPA national recommended
aquatic life water quality criteria for selenium.
In 2016, the EPA recommended a national selenium criterion expressed as four elements
(U.E. EPA 2016a). All elements are protective against chronic selenium effects in aquatic life.
Two elements are based on the concentration of selenium in fish tissue (eggs and ovaries, and
whole body or muscle) and two elements are based on the concentration of selenium in the water
column (two 30-day chronic values (lentic and lotic) and two intermittent values (lentic and
lotic). The EPA derived the 30-day chronic water column element from the egg-ovary element
by modeling selenium bioaccumulation in food webs of lotic and lentic aquatic systems. The
EPA recommended the intermittent values to address short-term exposures, such as
noncontinuous discharges containing selenium, that could contribute to chronic exposures and
effects through selenium bioaccumulation in either lotic or lentic systems. The EPA derived the
intermittent element based on the chronic 30-day water column element and the fraction of any
30-day period during which elevated selenium concentrations occur. These water column
criterion elements apply to the total of all oxidation states (selenite, selenate, organic selenium,
and any other forms; See Appendix L in U.S. EPA (2016a) for Analytical Methods for
Measuring Selenium). Aquatic communities are expected to be protected by the EPA's
recommended chronic criterion from potential acute effects of selenium if adopted and applied
by states. Chapman et al. (2009) noted that selenium acute toxicity has been reported rarely in
the aquatic environment. The most harmful effects of selenium on aquatic life and aquatic-
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dependent wildlife come from the bioaccumulation of selenium through the food web (see Part
2.4 of this document below). As such, these chronic effects occur at lower concentrations of
selenium than acute exposures; thus an acute criterion element was not derived.
The EPA has not established national selenium criteria recommendations for the
protection of aquatic-dependent wildlife. However, the EPA has been involved in two separate
efforts dealing with wildlife criteria for selenium. On December 12, 2011, the EPA approved a
selenium wildlife criterion for Gilbert Bay of the Great Salt Lake (U.S. EPA 201 la).1 The EPA
approved criterion was 12.5 mg/kg dry weight (dw) in bird egg tissue that is a geometric mean
over the nesting season to be applied to Gilbert Bay of the Great Salt Lake. On June 30, 2016,
the EPA proposed to revise the current federal CWA selenium water quality criteria applicable to
the San Francisco Bay and Delta to ensure that the criteria are protective of aquatic life and
aquatic-dependent wildlife. Within the analysis that supports the final rule, the EPA reviewed
avian toxicity studies and determined that the most "at risk" birds in this system are expected to
be protected by the final criteria (U.S. EPA 2016b).2
1.2 California Toxics Rule
On May 18, 2000, the EPA promulgated Water Quality Standards; Establishment of
Numeric Criteria for Priority Toxic Pollutants for the State of California at 65 FR 31681
(hereafter referred to as the California Toxics Rule or CTR).3 The CTR established numeric
water quality criteria for priority toxic pollutants for inland surface waters and enclosed bays and
estuaries within California. The EPA promulgated the CTR after California rescinded its water
quality control plans containing pollutant objectives (criteria). The criteria that the EPA
previously promulgated for California in the National Toxics Rule (NTR), together with the
criteria promulgated in the CTR and California's designated uses and anti-degradation
provisions, set water quality standards for priority toxic pollutants for inland surface waters and
enclosed bays and estuaries in California.
Since research documented in U.S. EPA (2016a) demonstrates that the most significant
exposure pathway of selenium to species of concern is through diet, the freshwater criteria for
selenium from the CTR, based solely on direct water column toxicity, is not considered
1 https://dea.utah.gov/water-aualitv/great-salt-lake-water-qualitv-standards
2 https ://www. gpo. gov/fdsvs/pkg/FR-2016-07-15/pdf/2016-16266.pdf
3 https://www.gpo.gov/fdsvs/pkg/FR-2000-05-18/pdf/0Q-l 1106.pdf
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adequately protective of species in California because direct water column toxicity is known not
to be a major route of toxicity to oviparous (egg-laying) aquatic and aquatic-dependent
vertebrate species (Chapman 2010; U.S. EPA 2016a). This technical support document (TSD)
provides a scientifically-defensible revised selenium water quality criterion based on dietary
exposures to selenium for certain waters in California in accordance with CWA section 303(c)
and EPA's implementing regulations. This criterion is based on the best available data and best
professional scientific judgments on the toxicological effects of selenium. The criterion herein
relies heavily on the documented science supporting the EPA's 2016 final recommended
freshwater chronic criterion for selenium (U.S. EPA 2016a), as well as additional toxicity and
exposure data specific to aquatic-dependent wildlife in California that was not part of the aquatic
life criterion, and the overarching guidance outlined in the EPA's "Guidelines for Deriving
Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their
Uses" (Stephan et al. 1985). The criterion also reflects public comments and feedback the EPA
received on the proposed rulemaking in order to ensure broad protection for both aquatic and
aquatic-dependent species.
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Part 2 Problem Formulation
2.1 Overview of Selenium Sources and Occurrence in California
Selenium is a naturally occurring element present in sedimentary rocks and soils. It is
present in the aquatic environment as selenite and selenate, as organic forms such as selenium
methionine through transformation by algae (Simmons and Wallschlager 2011; LeBlanc and
Wallschlager 2016), or as methyl derivatives of selenium through methylation by bacteria
(Ranjard et al. 2003). There are around 40 known selenium-containing minerals, some of which
can have as much as 30% selenium, but all are rare and generally occur together with sulfides of
metals such as copper, zinc, and lead (Emsley 2011). Sedimentary rocks, particularly shales,
have the highest naturally occurring selenium content (Burau 1985). The distribution of organic-
enriched, sedimentary shales, petroleum source rocks, ore deposits, phosphorites, and coals, in
which selenium typically co-occurs, is well characterized in the United States (Presser et al.
2004). Natural weathering of geologic strata containing selenium can lead to selenium leaching
into groundwater and surface water. Two major categories of anthropogenic activities are known
to cause increased selenium mobilization and introduction into aquatic systems. The first is the
mining of metals, minerals, and refinement and combustion of fossil fuels; the second is
irrigation of selenium-rich soils. Atmospheric emissions of selenium can originate from several
sources including power plants and other facilities that burn coal or oil, selenium refineries that
provide selenium to industrial users, base metal smelters and refineries, resource extraction
industries, milling operations, and end-product manufacturers (e.g., semiconductor
manufacturers, ATSDR (2003)). Airborne selenium particles can settle either on surface waters
or on soils from which selenium can be further transported and deposited into water bodies
through ground or surface water conveyances or runoff.
Mining activities bring selenium-enriched deposits to the surface, where they are exposed
to physical weathering processes. The release of selenium related to resource extraction activities
is most common in the phosphate deposits of southeast Idaho and adjacent areas of Wyoming,
Montana, and Utah, and in coal mining areas in portions of West Virginia, Kentucky, Virginia,
and Tennessee (Presser et al. 2004). Where selenium-containing minerals, rocks, and coal are
mined, selenium can be mobilized when rock overburden and waste materials are crushed,
increasing the surface area and exposure of the material to weathering processes. Selenium
contamination of surface waters can also occur when sulfide deposits of iron, uranium, copper,
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lead, mercury, silver, and zinc are released during the mining and smelting of these metal ores.
Additionally, when coal is burned for power production, selenium can enter surface waters as
drainage from fly-ash ponds and fly-ash deposits on land (Gillespie and Baumann 1986). Fly ash
deposits have a high surface area to volume ratio, resulting in rates of selenium in leachate
several times higher than from the parent feed coal (Fernandez-Turiel et al. 1994). The refining
and burning of crude oil containing high levels of selenium can also be a major source of loading
in certain water bodies via direct discharge and atmospheric deposition, respectively (Maher et
al. 2010).
High selenium concentrations are found in phosphoritic sedimentary rock such as marine
shales and sulfide ore bodies (Mayland et al. 1989). Cretaceous marine sedimentary deposits
have weathered to produce high selenium soils in many areas of the western United States
(Lemly 1993b). In California, areas with Tertiary and Cretaceous marine sedimentary deposits
are known to have elevated selenium (Figure 2-1). Watersheds in these areas may have elevated
selenium levels in water, especially if human disturbances to the geological sedimentary deposits
in these areas are high (Seiler et al. 1999). For instance, human disturbances have included
expanding the width and depth of open drainage channels for flood control purposes in
agricultural and urbanized areas, and conducting construction activities in the upland hills that
contain marine shales, such that these activities have disrupted and exposed the underlying
selenium-bearing marine sedimentary deposits subjecting them to erosion, weathering, and
transport to downslope areas in the watershed.
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0 250 500 KILOMETERS
Figure 2-1. Areas of California with seleniferous marine geology.
Modified from: Seiler et al. (1999).
Irrigation of selenium-rich soils for crop production in arid and semi-arid regions of the
country can mobilize selenium and move it off-site in drainage water that has leached through
soil. Where deposits of Cretaceous marine shales occur, they can weather to produce high
selenium soils; such soils are present in many areas of the western United States (Lemly 1993b).
Selenium is abundant in the alkaline soils of the Great Plains, and some ground waters in
California, Colorado, Kansas, Oklahoma, South Dakota, and Wyoming contain elevated
concentrations of selenium due to weathering of and leaching from rocks and soils. In semi-arid
areas of the West, irrigation water applied to soils containing soluble selenium can leach
selenium. The excess water (from tile drains to irrigation return flow) containing selenium can be
discharged into basins, ponds, or streams. For example, elevated selenium levels at the Kesterson
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Reservoir in California originated from agricultural irrigation return flow collected in tile drains
that discharged into the reservoir (Ohlendorf et al. 1986). Areas of California susceptible to
selenium contamination from agricultural irrigation are shown in Figure 2-2.
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0 250 500 KILOMETERS
Figure 2-2. Areas of California susceptible to selenium contamination (gray) and where
agricultural land is irrigated (green).
Overlap of gray and green show areas susceptible to selenium discharge from irrigation.
Modified from: Seiler et al. (1999).
Figure 2-3 shows the distributions and abundances of total selenium concentrations in
California water bodies collected over a 10-year period from October 5, 2004 to June 3, 2014
(CEDEN 2015). The total selenium concentration data included 270 water bodies (94% lotic and
6% lentic) and 11,290 water samples collected throughout California. The samples were
collected and analyzed by multiple organizations that conduct water quality monitoring in
California. The data results are uploaded into the California Environmental Data Exchange
Network (CEDEN) database by those monitoring organizations. The concentration distributions
that are binned in the map shown in Figure 2-3 show the data results in relation to the California
Toxics Rule (CTR) selenium chronic water quality criterion of 5 |ig/L, which applied as the
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regulatory water quality criterion over the 10-year sampling period. The map shows that most of
the field sampling occurred in the central San Joaquin Valley, Central Coast, Los Angeles, and
San Diego areas. These same sampling areas also had the largest share of exceedances of the 5
|ig/L selenium chronic water quality criterion. As previously noted, these are areas of California
that have seleniferous marine and continental sedimentary deposits.
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Carson
Gity
cramento
Las
Vegas
Total Selenium (ng/L) range in
CA Surface Waters (2004-2014)
Figure 2-3. Distributions and abundances of total selenium concentrations (jug/L) in surface
water samples collected from October 5, 2004 through June 3, 2014.
The California Toxics Rule (CTR) water quality criterion for selenium is currently set at 5 |ig/L.
The data were accessed from the California Environmental Data Exchange Network website
(CEDEN: www.ceden.org/) on February 4, 2015.
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2.2 Selenium Speciation in Aquatic Systems
The fate and transport of selenium in aquatic systems is affected by the distribution of
selenium species and their transformations in water, sediment, and biota. These transformations
include the assimilation and conversion of inorganic selenium to organic selenium species in
plants and microbes that are transferred to higher trophic level consumer species throughout the
aquatic food web.
Aquatic organisms are exposed to a combination of predominantly organic selenium
forms present in the food web, which result from transformation of inorganic forms entering
aquatic environments. Organisms accumulate selenium via trophic transfer throughout their life
history reaching steady-state when elimination equals uptake. Effects to reproductive stages
reflect the integrated exposures to transformed inorganic and organic species of selenium. The
bioavailability and toxicity of selenium depend on both its concentration and chemical speciation
(Cutter and Cutter 2004; Meseck and Cutter 2006; Riedel and Sanders 1996). Selenium exists in
four oxidation states (VI, IV, 0, -II) and in a wide range of chemical forms across these oxidation
states (Doblin et al. 2006; Maher et al. 2010; Meseck and Cutter 2006). In the effects assessment
that follows, we have correlated the adverse effects on aquatic life with total dissolved selenium.
In oxygenated surface waters, the primary dissolved selenium species are selenate
(SeC>42 , or Se[VI]) and selenite (SeCte2 , or Se[IV]), as well as dissolved organic selenides (-II)
formed from fine particulate organic matter (e.g., Doblin et al. 2006; Meseck and Cutter 2006).
The relative abundance of selenate and selenite may depend on relative contributions from the
geologic and anthropogenic sources of selenium to the receiving waters if there is negligible
inter-conversion between the two species (e.g., Maher et al. 2010), or may be influenced by
interconversions (Simmons and Wallschlager 2011). Aqueous selenite is more abundant than
selenate when the majority of selenium originates from discharges from coal fly ash tailings or
oil refineries (e.g., Cutter 1989; Huggins et al. 2007). Particulate species in the water column
include selenate, selenite, and elemental selenium [Se(0)] bound to resuspended sediments and
organic particles, as well as particulate organic selenium species incorporated into suspended
detritus (e.g., Cutter and Bruland 1984; Meseck and Cutter 2006).
In sediments, selenate and selenite can be reduced to iron selenides or elemental selenium
under abiotic or biotic processes; elemental selenium and selenides can be converted to selenate
under oxidizing conditions (Maher et al. 2010). For example, selenate can be reduced to
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elemental selenium in sediments (e.g., Oremland et al. 1990) in the presence of iron oxides
(Chen et al. 2008) and iron sulfides (Breynaert et al. 2008). Elemental selenium and organic
selenides are produced by selenate-reducing microbes in sediments. Overall, the reduction of
selenate and particularly selenite in sediments increases with increasing sediment organic matter
(Tokunaga et al. 1997). Selenite in particular is readily bound to iron and manganese oxy-
hydroxides (Maher et al. 2010), and is readily adsorbed to inorganic and organic particles,
particularly at a lower pH range (e.g., McLean and Bledsoe 1992; Tokunaga et al. 1997).
Microbial reduction of selenite to organic forms (via methylation) increases the solubility and
bioavailability of selenium (Simmons and Wallschlager 2005). Plants and algae produce volatile
selenium species by biomethylation of excess selenium, which upon reaching the sediment can
be transformed to a more bioavailable species or deposited in the sediments and effectively
removed from the system (Diaz et al. 2009). Depending on environmental conditions, the
reduction processes described above are largely reversible, as elemental selenium and selenides
in sediments can be oxidized to selenate through microbial or abiotic transformations (e.g.,
Maher et al. 2010; Tokunaga et al. 1997).
The most important aspect of selenium chemistry, with respect to its toxicity to aquatic
organisms, is in the uptake and transformation of dissolved inorganic selenium in the tissues of
primary producers at the base of the food web. The main route of entry of selenium into aquatic
food webs is from the consumption of selenium incorporated in the tissue of primary producers,
and to a lesser degree, from the consumption of sediments (Doblin et al. 2006; Luoma and
Presser 2009). For algae, dissolved species of selenite and organic selenides are more
bioavailable than selenate (Baines et al. 2001; Luoma et al. 1992). In vascular plants, selenate
uptake is greater than for the other dissolved species, as most selenium uptake occurs in the
roots, and selenate is more easily transported to the shoots and leaves than selenite or organic
selenides (Dumont et al. 2006). Following uptake, selenium is metabolized into a variety of
organic species that are assimilated into plant tissues. Selenium metabolism in plants is
analogous to sulfur metabolism (e.g., Dumont et al. 2006; Ouerdane et al. 2013). Selenate is
reduced to selenite, which is then reduced to selenide in a process involving reduced glutathione
(Dumont et al. 2006). Selenide is converted to selenocysteine, which is then converted to
selenomethionine (Dumont et al. 2006). In addition to selenocysteine and selenomethionine, a
variety of other organic selenium species can be formed; however, selenocysteine, and
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particularly selenomethionine are toxicologically important because these amino acids
nonspecifically replace cysteine and methionine in proteins and are more bioavailable to higher
trophic level consumers (Fan et al. 2002; Freeman et al. 2006).
The chemical form of selenium that dominates a location is usually dependent on its
sources, effluent treatments, and biogeochemical processes in the receiving waters. Irrigation
activities in areas with seleniferous soils typically mobilize selenate (SeC>42 , or Se[VI]) (Seiler et
al. 2003). Combustion of coal for power generation creates predominantly selenite (SeC>32 , or
Se[IV]) in the fly ash waste due to the temperatures, pH, and redox conditions involved with the
process (Huggins et al. 2007). Similar conditions during refinement of crude oil can also result in
high concentrations of selenite relative to selenate, as was observed in the San Francisco Bay
estuary in the 1980s (Cutter 1989). Although selenite is the dominant species in the discharges
resulting from crude oil refining and coal burning using conventional technologies, the
implementation of alternative treatment technologies can alter the relative concentrations of
selenate and selenite. For example, in scrubbers with forced oxidation systems that produce
strong oxidizing conditions and high temperatures, most of the discharged selenium is in the
form of selenate (Maher et al. 2010). For flue gas desulfurization systems that are the inhibited
oxidation type, the selenium chemistry is more complex, and selenite may not be the primary
form emitted (Petrov et al. 2012). Table 2-1 shows the predominant chemical forms of selenium
that are associated with different activities and industries.
Table 2-1. Predominant Chemical Forms of Selenium in Discharges Associated with
Different Activities and Industries.
Selenium Form
Sources
Selenate
Agricultural irrigation drainage
Treated oil refinery effluent
Mountaintop coal mining/ valley fill leachate
Copper mining discharge
Selenite
Oil refinery effluent
Fly ash disposal effluent
Phosphate mining overburden leachate
Organoselenium
Treated agricultural drainage (in ponds or lagoons)
Source: Cutter and Diego-McGlone 1990; Presser and Ohlendorf 1987; Zhang and Moore 1996.
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2.3 Bioaccumulation of Selenium in Aquatic Systems
Dissolved selenium uptake by animals is slow, whatever the chemical form, such that
under environmentally relevant conditions, dissolved selenium in the water column makes little
or no direct contribution to bioaccumulation in animals (Lemly 1985; Ogle and Knight 1996),
but does influence the concentration of selenium in particulate matter. Selenium bioaccumulation
in aquatic organisms occurs primarily through the ingestion of food (Fan et al. 2002; Luoma et
al. 1992; Maher et al. 2010; Ohlendorf et al. 1986; Presser and Ohlendorf 1987; Presser et al.
1994; Saiki and Lowe 1987). However, unlike other bioaccumulative contaminants such as
mercury, the single largest step in selenium accumulation in aquatic environments occurs at the
base of the food web where algae and other microorganisms accumulate selenium from water by
factors ranging from several hundred to tens of thousands (Luoma and Presser 2009; Orr et al.
2012; Stewart et al. 2010). Bioaccumulation and trophic transfer through aquatic food webs are
the major biogeochemical pathways of selenium in aquatic ecosystems. Dissolved selenium
oxyanions (selenate, selenite) and organic selenides are assimilated into the tissues of aquatic
primary producers (trophic level 1 organisms), such as periphyton, phytoplankton, and vascular
macrophytes; and subsequently biotransformed into organoselenium. These organisms, together
with other particle-bound selenium sources, constitute the particulate selenium fraction in the
water column. Selenium from this particulate fraction is then transferred to aquatic primary
consumers such as zooplankton, insect larvae, larval fish, and bivalves (trophic level 2), and then
to predators such as fish and birds (trophic level 3 and higher). In addition to the presence of
selenium in the water, the process of selenium bioaccumulation in aquatic life residing in
freshwater systems depends on several factors specific to each aquatic system. These factors
include:
Water residence time. Residence time is a measure of the average time a water molecule
will spend in a specified region of space. Residence time influences both the proportion of
selenium found in particulate and dissolved forms and the predominant chemical form of
selenium. Organisms in waters with long residence times such as lakes, ponds, reservoirs,
wetlands, or estuaries will tend to bioaccumulate more selenium than those living in waters with
shorter residence times such as rivers and streams (ATSDR 2003; EPRI 2006; Luoma and
Rainbow 2005; Simmons and Wallschlager 2005). Several interrelated factors affect selenium's
greater bioaccumulation potential in slow moving systems including food web complexity and
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the organic content and reduction/oxidation potential of underlying sediments. Therefore,
selenium toxicity in flowing waters with shorter residence times may only be apparent
downstream of their selenium sources, whereas waters with longer residence times are more
likely to exhibit selenium toxicity near their sources (Presser and Luoma 2006).
Distribution of selenium between particulate and dissolvedforms. Selenium is found in
both particulate and dissolved forms in water, but direct transfer of selenium from water to
animals is only a small proportion of the total exposure. The proportion of selenium found in
particulate matter (algae, detritus, and sediment) is important because it is the primary avenue for
selenium entering into the aquatic food web (Luoma and Rainbow 2005; Luoma et al. 1992;
Ohlendorf et al. 1986; Presser and Luoma 2006; Presser and Ohlendorf 1987; Presser et al. 1994;
Saiki and Lowe 1987).
Bioaccumulation in prey. Trophic level 1 organisms such as periphyton and
phytoplankton, as well as other forms of particulate material containing selenium, such as
detritus and sediment, are ingested by trophic level 2 organisms such as mollusks, planktonic
crustaceans, and many insects, increasing the concentration of selenium in the tissues of these
higher-level organisms. Differences in the physiological characteristics of these organisms result
in different levels of bioaccumulation. Also, based on the limited toxicity data available,
selenium effects on invertebrates typically appear to occur at concentrations higher than those
that elicit effects on vertebrates (e.g., fish and birds) that prey upon them (Janz et al. 2010).
Additionally, certain molluscan taxa such as mussels and clams can accumulate selenium to a
much greater extent than planktonic crustaceans and insects (although the levels do not seem to
be toxic to the mussels) due to higher ingestion rates of both particulate-bound (algae) and
dissolved selenium from the water column through filter feeding, as well as the lower rate at
which they eliminate selenium (Luoma and Rainbow 2005; Stewart et al. 2013).
Trophic transfer to predators. Bioaccumulation of selenium by higher trophic level
organisms, such as trophic level 3 and 4 fish and birds, is highly influenced by the specific food
web of the aquatic environment that they inhabit. Prey selection influences the amount of
selenium bioaccumulated by predatory fish and birds (Ackerman and Eagles-Smith 2009; Luoma
and Presser 2009; Ohlendorf et al. 1986; Stewart et al. 2010). For example, fish and birds that
primarily consume freshwater mollusks (e.g., redear sunfish and lesser scaup) will exhibit greater
selenium bioaccumulation than fish and birds that consume primarily insects or crustaceans from
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waters with the same concentration of dissolved selenium because mollusks tend to accumulate
selenium at higher concentrations than other trophic level 2 organisms, as noted above (Luoma
and Presser 2009; Stewart et al. 2004).
Because egg-laying (oviparous) vertebrates such as fish and birds are the most sensitive
vertebrates to selenium effects, (Janz et al. 2010), these vertebrate consumers are also the most
vulnerable groups to the potentially harmful effects of selenium, such as reproductive
impairments, and selenium poisoning and therefore are the focal point of most selenium
environmental assessments and criteria derivations (Ogle and Knight 1996; Stewart et al. 2010).
2.4 Effects and Biota
2.4.1 Mode of Action and Toxicity of Selenium
Selenium is a naturally occurring chemical element that is also an essential micronutrient.
Trace amounts of selenium are required for normal cellular function in animals. However,
selenium at amounts not much above nutritional levels can have toxic effects, making it one of
the most toxic of the biologically essential elements (Chapman et al. 2010). Egg-laying
vertebrates have a lower tolerance than do mammals, and the transition from levels of selenium
that are biologically essential to those that are toxic for these species occurs across a narrow
range of exposure concentrations (Chapman et al. 2009, 2010; Haygarth 1994; Luckey and
Venugopal 1977; U.S. EPA 1987, 1998).
As a member of the Group 16 nonmetallic elements, selenium displays similar
characteristics to sulfur. Selenium can replace sulfur in two amino acids, the seleno-forms being
selenomethionine and selenocysteine. It has been a long-standing hypothesis that the cause of
malformations in egg-laying vertebrates is due to the substitution of selenium for sulfur in these
amino acids and their subsequent incorporation into proteins, which causes disruption of the
structure and function of the protein. When present in excessive amounts, selenium is
erroneously substituted for sulfur, resulting in the formation of a triselenium linkage (Se-Se-Se)
or a selenotrisulfide linkage (S-Se-S), either of which was thought to prevent the formation of the
normal disulfide chemical bonds (S-S). The result was thought to be distorted, dysfunctional
enzymes, and protein molecules that impaired normal cellular biochemistry (Diplock and
Hoekstra 1976; Reddy andMassaro 1983; Sunde 1984).
More recent research, however, suggests that selenium's role in oxidative stress plays a
part in embryo toxicity, whereas selenium substitution for sulfur does not. Contrary to what was
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previously hypothesized, the substitution of selenomethionine for methionine does not appear to
affect either the structure or function of proteins (Egerer-Sieber et al. 2006; Mechaly et al. 2000;
Yuan et al. 1998). The reason is apparently due to selenium not being distally located in
selenomethionine; a terminal methyl group on this amino acid insulates the protein from
selenium's effect on its tertiary structure and its function. Selenocysteine is present in several
enzymes (e.g., glutathione peroxidases) and unlike selenomethionine its incorporation into
proteins is highly regulated (Stadtman 1996). Selenium's incorporation into proteins either as
selenomethionine or selenocysteine therefore does not affect their functional and structural
properties. The role of selenium-induced oxidative stress in embryo toxicity and teratogenesis
appears to be related to glutathione homeostasis. A review of bird studies by Hoffman (2002)
showed exposure to selenium-altered concentrations and ratios of reduced to oxidized
glutathione and increasing measurements of oxidative cell damage. Palace et al. (2004)
suggested oxidative stress due to elevated selenium levels results in pericardial and yolk sac
edema in rainbow trout embryos. In addition to oxidative stress, Kupsco and Shlenk (2014)
found selenomethionine may disrupt endoplasmic reticulum (ER) homostasis in the Japanese
medaka which could result in teratogenesis and embryo lethality. Evidence for the role of
oxidative and ER stress in selenium toxicity is growing but mechanistic studies are still needed
to better understand its effects on egg-laying vertebrates. For a more in-depth discussion on the
mechanism of toxicity at the cellular level, including the evidence against sulfur substitution as a
cause and the role of oxidative stress, see Janz et al. (2010).
2.4.2 Narrow Margin between Sufficiency and Toxicity of Selenium
Selenium is an essential nutrient that is incorporated into functional and structural
proteins as selenocysteine and selenomethionine. Several of these proteins are enzymes that
provide cellular antioxidant protection. Selenomethionine is readily oxidized, and its antioxidant
activity arises from its ability to deplete reactive oxygen species. Selenomethionine is required as
a mineral cofactor in the biosynthesis of glutathione peroxidases. All the classic glutathione
peroxidases contain selenium and are found to be involved in the catalytic reaction of these many
enzymes (Allan et al. 1999). The major functions of the glutathione peroxidases involve the
reduction of hydrogen peroxide to water at the expense of the oxidation of glutathione, the
enzyme's cofactor, an important antioxidant process at normal dietary levels, and the
detoxification of lipid hydroperoxides. Selenium has a narrow range encompassing what is
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beneficial for biota and what is detrimental. This margin between essentiality and toxicity of
selenium is the narrowest of all trace elements, making the risk of negative impacts from
environmental contamination extremely high (Luoma and Rainbow 2008).
Aquatic and terrestrial organisms require low levels of selenium in their diet to sustain
metabolic processes, whereas excess concentrations of selenium that are approximately an order
of magnitude greater than the required level have been shown to be toxic to fish and birds
(Ohlendorf and Heinz 2011; Palace et.al. 2004). Dietary requirements in fish have been reported
to range from 0.05 to 1.0 mg Se/kg dw (Watanabe et al. 1997). Selenium requirements for
optimum growth and liver glutathione peroxidase activity in channel catfish were reported as
0.25 mg Se/kg dw (Gatlin and Wilson 1984). Estimated selenium dietary requirements in hybrids
of striped bass, based on selenium retention, were reported as 0.1 mg Se/kg dw (Jaramillo 2006).
Studies in rainbow trout were the first to identify the narrow range margin between essentiality
and toxicity of selenium, with toxicity occurring at between seven and 30 times greater dietary
exposure than essential levels (Hilton and Hodson 1983; Hodson et al. 1980). In birds, egg
selenium concentrations lower than 0.66 mg Se/kg dw may indicate inadequate selenium in the
diet, resulting in poor adult health and reproduction. In areas without selenium contamination,
background concentrations of selenium in bird eggs are 3 to 4 mg Se/kg dw, with maximum
individual values usually <5 mg Se/kg dw (Ohlendorf and Heinz 2011; Ohlendorf et al. 1986;
Skorupa et al. 1996; U.S. DOI 1998). Selenium deficiency has been found to affect humans (U.S.
EPA 1987), sheep and cattle (U.S. EPA 1987), deer (Oliver et al. 1990), fish (Thorarinsson et al.
1994; U.S. EPA 1987; Wang and Lovell 1997; Wilson et al. 1997), aquatic invertebrates (Audas
et al. 1995; Caffrey 1989; Cooney et al. 1992; Cowgill 1987; Cowgill and Milazzo 1989; Elendt
1990; Elendt and Bais 1990; Harrison et al. 1988; Hyne et al. 1993; Keating and Caffrey 1989;
Larsen and Bjerregaard 1995; Lim and Akiyama 1995; Lindstrom 1991; U.S. EPA 1987; Winner
1989; Winner and Whitford 1987), and algae (Doucette et al. 1987; Keller et al. 1987; Price
1987; Price et al. 1987; Thompson and Hosja 1996; U.S. EPA 1987; Wehr and Brown 1985).
The predominance of research on selenium deficiency in invertebrates and algae is related to
optimizing the health of test organisms cultured in the laboratory.
2.4.3 Adverse Effects of Selenium in Fish and Birds
The best documented, overt, and severe toxic symptoms in fish are reproductive
teratogenesis and larval mortality. Egg-laying vertebrates appear to be the most sensitive taxa,
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with toxicity resulting from maternal transfer to eggs. Selenomethionine is incorporated into
vitellogenin in fish liver and then transferred to eggs during vitellogenesis where it is cleaved
into distinct yolk proteins. In fish, the yolk proteins lipovitellin and phosvitin have been shown
to contain selenium (Janz et al. 2010; Janz 2011). In studies involving young organisms exposed
through transfer of selenium from adult female fish into their eggs, the most sensitive diagnostic
indicators of selenium toxicity in vertebrates occur when developing embryos metabolize
organic selenium that is present in egg albumen or yolk. It is then further metabolized by larval
fish after hatching. Enzymes such as cytochrome P-450 or flavin monoxygenase can
biotransform organoselenium compounds into selenoxides (Palace et al. 2004).
A variety of lethal and sublethal deformities (terata) can occur in developing fish exposed
to selenium, affecting both hard and soft tissues (Lemly 1993a). Developmental malformations
are among the most conspicuous and diagnostic symptoms of chronic selenium poisoning in fish
and have been used to identify impacts of selenium on fish populations (Lemly 1997; Maier and
Knight 1994). Deformities in fish that affect feeding or respiration can be lethal shortly after
hatching. Terata that are not directly lethal, but distort the spine and fins, can reduce swimming
ability and overall fitness. Because the rate of survival of deformed young would be less than
that for normal young, the percentage of deformed adults observed during biosurveys will likely
underestimate the underlying percentage of deformed young, although quantitation of the
difference is ordinarily not possible.
The most sensitive indicators of selenium toxicity in fish larvae are effects modulated
through the reproductive process and exhibited in fish larvae as teratogenic deformities such as
skeletal, craniofacial, and fin deformities, and various forms of edema that result in mortality
(Lemly 2002). The toxic effect generally evaluated is the reduction in the number of normal
healthy offspring compared against the initial number of eggs. In studies of young organisms
exposed to selenium solely through their own diet rather than via maternal transfer, reductions in
survival and/or growth are the effects that are generally evaluated.
Movement of selenium through the aquatic food web (e.g., aquatic plants, invertebrates
and fish) has been shown to lead to selenium bioaccumulation in aquatic-dependent wildlife,
which results in reproductive impairments and malformations (Hoffman et al. 1988; Hothem and
Ohlendorf 1989; Ohlendorf et al. 1986; Skorupa and Ohlendorf 1991). For birds, diet and
subsequent maternal transfer represent the critical selenium exposure route. Most of the selenium
21
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found in bird eggs is mobilized exogenously from the maternal diet rather than endogenously
from maternal tissue (DeVink et al. 2008; Ohlendorf and Heinz 2011). Thus, the most direct
means of determining the potential for toxic effects of selenium in birds is through measuring
egg selenium concentrations (Adams et al. 1998; Fairbrother et al. 1999; Ohlendorf and Heinz
2011). Additionally, given the rapid patterns of selenium accumulation and loss observed in
birds, selenium concentrations measured in eggs will also likely represent contamination of the
local environment.
Bird embryos are very sensitive to selenium (Moxon and Olson 1974; NAS 1976; Ort and
Latshaw 1977, 1978). The more sensitive chronic effects identified in birds are related to
reproductive impairments. Reproductive impairment is a general term including decreased
fertility, reduced egg hatchability (embryo mortality), and increased incidence of deformity in
embryos (Ohlendorf and Heinz 2011). Selenium exposure may cause multiple overt deformities
in bird embryos including hydrocephaly, missing eyes, twisted bills, and deformed limbs
(Hoffman and Heinz 1988; Hoffman et al. 1988; Ohlendorf and Heinz 2011). Toxicity studies on
birds show that thresholds for reduced egg hatchability are usually below those for teratogenic
effects (Ohlendorf 2003).
In 1983, incidents of mortality, congenital deformities, and reproductive failures in
aquatic birds were documented at Kesterson Reservoir (Merced County, CA), a U.S. Department
of Interior (DOI) National Wildlife Refuge located in the western San Joaquin Valley,
California. The Reservoir consisted of a series of twelve ponds within the Kesterson National
Wildlife Refuge (NWR) that were used for disposal of subsurface drainage from agricultural
fields. The analyses of food chain biota (such as plants, aquatic invertebrates, and fish) and bird
tissues or eggs showed that selenium was the only chemical found at concentrations high enough
to cause the adverse effects on bird health and reproduction that were observed (Ohlendorf
2002). Field studies, supported by findings from laboratory studies, revealed relationships
between exposure to high selenium diets, tissue selenium concentrations, and adverse effects
(Heinz et al. 1988, 1989, 1990; Hoffman and Heinz 1988). For example, the mean selenium
concentrations in bird eggs at Kesterson Refuge were usually 20 to 30 times higher than the
reference site at Volta Refuge, which did not receive agricultural subsurface drainage discharge
(Ohlendorf and Hothem 1995). All bird species mean egg concentrations at Volta were less than
3 mg/kg dw, which is typical of normal background, whereas mean egg concentrations at
22
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Kesterson were measured up to 69.7 mg/kg dw (Ohlendorf 2002). Similar occurrences of
impaired bird reproduction were subsequently observed elsewhere in the western U.S., including
in the Tulare Basin of California (Skorupa 1998a; Skorupa and Ohlendorf 1991).
2.5 Assessment Endpoints
Assessment endpoints are defined as "explicit expressions of the actual environmental
value that is to be protected" and are defined by an ecological entity (species, community, or
other entity) and its attribute or characteristics (U.S. EPA 1998). Assessment endpoints may be
identified at any level of organization (e.g., individual, population, community). In the context of
the Clean Water Act, aquatic life and aquatic-dependent wildlife criteria for toxic pollutants are
typically determined based on the results of toxicity tests with aquatic and aquatic-dependent
organisms in which unacceptable effects on growth, reproduction, or survival occurred. This
information is typically compiled into a sensitivity distribution based on genera and representing
the impact on taxa across the aquatic community. Criteria are intended to be protective of most
aquatic organisms in the community (i.e., approximately the 95th percentile of tested aquatic
organisms or aquatic-dependent wildlife representing the aquatic community).
Thus, the health of the aquatic ecosystem may be considered as an assessment endpoint
indicated by survival, growth, and reproduction. For more details on aquatic life assessment
endpoints for selenium see Section 2.6 in the EPA's 2016 "Aquatic Life Ambient Water Quality
Criterion for Selenium - Freshwater, 2016." This previously published aquatic life criterion was
developed using a genus sensitivity distribution (GSD), which represented the impact on taxa
across the aquatic community but focused on reproductive effects on the most sensitive aquatic
taxa, oviparous fish. For aquatic-dependent wildlife, there are significantly fewer toxicity studies
available that are focused on the assessment endpoints of survival, growth, and reproduction. For
this criterion, the EPA relied on toxicity studies from the most sensitive aquatic-dependent
wildlife species (mallard) tested to date to develop the aquatic-dependent wildlife assessment
endpoint based on mallard hatchability, a reproductive endpoint.
2.6 Measures of Ecological Effect
Each assessment endpoint requires one or more "measures of ecological effect," which
are defined as changes in the attributes of an assessment endpoint itself or changes in a surrogate
23
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entity or attribute in response to chemical exposure. Ecological effects data are used as measures
of direct and indirect effects to growth, reproduction, and survival of aquatic organisms.
The amount of toxicity testing data available for any given pollutant varies significantly,
depending primarily on whether any major environmental issues have occurred. An in-depth
evaluation of available data and subsequent review for data acceptability of selenium aquatic life
studies has been performed by the EPA (U.S. EPA 2016a; see Stephan et al. 1985 for additional
detail on data acceptability).
In conventional chronic tests used in many EPA aquatic life criteria documents,
organisms are exposed to contaminated water but fed a diet grown in uncontaminated media not
spiked with the toxicant prior to introduction into the exposure chambers. Such tests are not
suitable for deriving a criterion for a bioaccumulative pollutant unless (1) effects are linked to
concentrations measured in appropriate tissues, and (2) the route of exposure does not affect the
potency of residues in tissue. For selenium, the first condition might be met, but the second
condition is not, because the route of selenium exposure appears to influence the potency of a
given tissue residue (Cleveland et al. 1993; Gissel-Nielsen and Gissel-Nielsen 1978).
Consequently, water-only exposure tests (and any tests not relying on dietary exposure) were not
included in the EPA's 2016 aquatic life criteria for selenium (U.S. EPA 2016a) and are not
included in this assessment for determining criteria protective of aquatic-dependent wildlife.
Selenium toxicity in aquatic life and aquatic-dependent wildlife is primarily manifested
as reproductive impairment due to maternal transfer, resulting in embryo mortality and
teratogenicity. Measurements of fish tissue and bird tissue, such as eggs, are most closely linked
to the chronic adverse effects of selenium (Chapman et al. 2010), since chronic selenium toxicity
is based on the food chain bioaccumulation route, not a direct waterborne route. The following
parts of this TSD describe the approaches used to establish selenium effect concentrations in fish
tissue (U.S. EPA 2016a), and in bird egg, and to relate the concentrations in fish tissue and bird
egg to concentrations in water.
2.7 Selenium Effects Concentrations in Fish Tissues and Bird Eggs
Chronic measures of effect concentrations are the ECio, EC20, No Observed Effect
Concentration (NOEC), Lowest Observed Effect Concentration (LOEC), and Maximum
Acceptable Toxicant Concentration (MATC). The ECiois the concentration of a chemical that is
estimated to result in a 10 percent effect in a measured chronic endpoint (e.g., growth,
24
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reproduction, and survival); the EC20 corresponds to 20 percent effect. The NOEC is the highest
chemical concentration at which none of the observed effects are statistically different from the
control, as determined by hypothesis testing. The LOEC is the lowest test concentration at which
observed effects are found to be statistically different from the control. Finally, the MATC is
calculated as the geometric mean between the NOEC and the LOEC.
For selenium, in all cases the effect endpoint used in the estimation of chronic values
(e.g., EC 10 values) is an effect on offspring (with exposure via maternal transfer) from parents
exposed to selenium via diet. For fish and birds, selenomethionine was used exclusively in
dietary exposures in the lab, whereas field-exposed females would be exposed to a combination
of forms of selenium as a function of the selenium in their prey items. When considering the use
of the EC10 versus the EC20, an EC10 was determined to be a more appropriate measure of effect
concentration for tissue-based criteria given the nature of exposure and effects for this
bioaccumulative chemical. Historically, EC20 values have been used in the derivation of the EPA
criteria applicable to the water medium. While water concentrations may vary rapidly over time,
tissue concentrations of bioaccumulative chemicals are expected to vary gradually over time.
Thus, where concentrations of selenium in bird eggs and fish tissue are used as an effect
threshold, there is potential for sustained impacts on aquatic systems, relative to non-
bioaccumulative chemicals. Furthermore, it was found that the dose-response curves for
selenium across a broad range of fish genera are very steep compared to most toxicants, such that
a small change in selenium tissue concentration yielded a large increase in observed adverse
effect. These characteristically steep dose-response curves were also observed for mallards and
are likely present across additional bird genera (Ohlendorf 2003). Thus, selection of a more
protective effect endpoint level (EC 10) as the criterion basis was deemed appropriate. For more
information on methods used in the EPA's derivation of effects concentrations for aquatic life,
see the EPA's 2016 "Aquatic Life Ambient Water Quality Criterion for Selenium - Freshwater,
2016" This approach is consistent with the EPA's recent recommendations to States and Tribes
for setting selenium water quality criteria for aquatic life (U.S. EPA 2016a). In this document,
chronic values are presented as tissue concentrations (either fish egg-ovary, whole body fish
tissue, muscle fish tissue, or bird egg) of total selenium in units of mg/kg dry weight (dw).
25
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2.7.1 Water
As described in U.S. EPA (2016a), the EPA previously collaborated with the United
States Geological Survey (USGS) to develop a model (later published in Presser and Luoma
2010) that relates the concentration of selenium in fish tissue to the water column. The approach
models bioaccumulation and trophic transfer of selenium through aquatic food webs. Model
parameters are calculated using both field and laboratory measurements of selenium in water,
particulate material (algae, detritus and sediment), invertebrates, fish whole body, and fish egg-
ovary. Although the EPA and USGS use the same model to relate the concentration of selenium
in fish tissue to water, the EPA starts with selenium in the fish egg-ovary (reproductive effects
criterion) whereas USGS starts with selenium in the fish whole body. The EPA approach
therefore has the additional step of converting the concentration of selenium in the egg-ovary to
whole body or muscle tissue concentrations using a conversion factor. This model is described in
more detail in Section 3.2.1 of the EPA's 2016 "Aquatic Life Ambient Water Quality Criterion
for Selenium - Freshwater, 2016" as well as Parts 5.2, 5.3, and 5.4 of this document.
Additionally, for the purpose of developing water column criterion elements that would
also be protective of aquatic-dependent wildlife, the EPA used the model with appropriate
parameters to relate the concentration of selenium in bird eggs to water (Part 5.5.2). This
additional analysis showed that the water column criteria derived from fish tissue concentrations
(Part 5.5.1) are protective of aquatic-dependent wildlife. The default water column criterion
elements for California are the same as those defined in the Aquatic Life Ambient Water Quality
Criterion for Selenium - Freshwater, 2016. These water criterion elements are subordinate to the
bird and fish tissue criterion elements.
The EPA also developed a PBA for translating the fish and bird tissue elements into a
corresponding water-column criterion element that could be applied on a site-specific basis, as
appropriate. If using the PBA, the State will derive water-column criterion elements on a site-
specific basis that are translated from the fish and bird tissue criterion elements and therefore
correspond to the concentration of selenium in fish and bird tissue estimated to result in a 10
percent effect (lotic or lentic water bodies as described below in Part 5.5). A PBA-based water
criterion element would be subordinate to the bird and fish tissue criterion elements. As in U.S.
EPA (2016a), it would be derived by modeling transfer of selenium through the food web
resulting in the fish and bird tissue concentrations that yield the chronic reproductive effects of
26
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concern. In Part 5, the EPA discusses the translation of the tissue elements into water-column
concentrations using the mechanistic modeling approach and presents a translation for birds
(described below) that is comparable to the water-column translation for the fish tissue criterion
elements in the 2016 304(a) selenium criterion, and the default water column criterion elements
herein. An analysis of the translation from bird egg to water column criterion elements showed
that the water column element translated from fish tissue is also protective of aquatic-dependent
birds.
2.7.2 Summary ofAssessment Endpoints and Measures of Effect
The typical assessment endpoints for aquatic life and aquatic-dependent wildlife criteria
are based on effects on growth, deformity rates, reproduction, or survival of the assessed taxa.
These measures of effect on toxicological endpoints have potential consequences to populations
and are provided by results from toxicity tests with aquatic life and aquatic-dependent wildlife.
The toxicity values (i.e., measures of effect expressed as genus means) are used in the genus
sensitivity distribution of the aquatic community to derive the aquatic life criteria. For aquatic-
dependent wildlife, the tissue-based criterion is an ECio for mallard hatchability (a sensitive
endpoint for a sensitive species) exposed to selenomethionine and calculated from three
combined mallard toxicity studies. The tissue-based criterion was derived from toxicity data for
this one species since the current literature does not include sufficient toxicity data to develop a
sensitivity distribution for a range of avian species. However, mallard is the most sensitive
species for which there is selenium toxicity data (see Parts 4.2 and 4.6). Endpoints considered
and used in this assessment are listed in Table 2-2.
27
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Table 2-2. Summary of Assessment Endpoints and Measures of Effect Used in Criteria
Derivation for Selenium.
Assessment Endpoints
Measures of Effect
Fish: Survival, growth, and
reproduction/teratogenesis
of freshwater fish, other
freshwater vertebrates, and
invertebrate effects
For effects from chronic exposure:
1. ECio concentrations in egg and ovary for offspring mortality
and deformity.
2. Measured or estimated reproductive ECio in whole body and
muscle.
Note: The chronic criterion is expected to be protective of acute
effects.
Birds: Reproduction in
birds (hatchability,
teratogenesis, chick
survival, and growth)
For effects from chronic exposure:
1. ECio concentrations in bird egg for hatchability.
Note: The chronic criterion is expected to be protective of acute
effects.
2.7.5 Conceptual Model of Selenium Effects on Aquatic Life and Aquatic-Dependent Wildlife
A conceptual model depicts the relationship between a chemical stressor and ecological
compartments, linking exposure characteristics to ecological endpoints. The conceptual model
provided in Figure 2-4 summarizes potential pathways of selenium exposure for aquatic life and
aquatic-dependent wildlife.
Selenium initially enters the aquatic environment through runoff, leachate, and
wastewater discharges from mining, oil refineries, disturbance and excavation in Cretaceous
marine shales, and agricultural activities. Selenium entering the aquatic environment occurs as
selenate, selenite, and selenides in dissolved and particle-bound forms and readily sorbs to
surfaces, such as sediment and particulate matter in the water column, which is depicted in the
conceptual model (Figure 2-4). Exposure pathways for the biological receptors of concern (i.e.,
non-target aquatic-dependent wildlife) and potential effects (e.g., reproductive impairment by
reduced hatch, deformities, and mortality) in those receptors are represented in the conceptual
model (Figure 2-4). Both direct (i.e., exposure from the water column which is represented by *)
and indirect (i.e., bioconcentrated by producers and bioaccumulated by consumers in higher
trophic levels represented by **) pathways are represented in the conceptual model (Figure 2-4).
28
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Se Source
Point Sources
(from municipal dischargers,
mining of coal, phosphate, metals,
and sulfide minerals)
DC
U
u
Se in Water
Dissolved & Particle-Bound
Selenate, Selenite, &
Selenides
Se Source
Nonpoint Sources
(from disturbance and excavation
in Marine Cretaceous shales and
irrigation of seleniferous soils in
Western U.S. only)
Wj
to
.3
tr
"B
V
d
C/)
tJ
2
w
o'
Se in Sediment
Selenate, Selenite, & Selenides
Aquatic Life
Producers
Is' Trophic Transfer
(from phytoplankton, periphyton, macrophytes; e.g., algae, cyanobacteria, waterweed/common eelgrass)
c.
4(
U
1)
OS
Consumers
2nd Trophic Transfer
(to zooplankton, macroinvertebrates;
e.g., cladocerans/copepods &
mayflies/ribbed mussels)
I
Consumers
3rd Trophic Transfer
(to predatory fish;
e.g., longtiose dace/
American shad)
Consumers
4th Trophic Transfer
(to predatory fish;
e.g., largemouth bass/
striped bass)
Aquatic-Dependent Wildlife
Consumers
3rd Trophic Transfer
(to predatory birds; e.g., American
coot/lesser scaup)
I I
Consumers
4'" Trophic Transfer
(to predatory birds;
e.g.. great blue heron/bald eagle)
Figure 2-4. Conceptual model diagram of sources, compartinental partitioning, and trophic
transfer pathways of selenium in the aquatic environment and bioaccumulation and effects in
aquatic-dependent wildlife.
Selenium sources represented in ovals, compartments within the aquatic ecosystem represented by rectangles, and
effects (on trophic levels of aquatic-dependent wildlife, represented by shaded box) in pentagons. Examples of
organisms in each trophic transfer provided as freshwater/marine. Weighted arrows indicate relative proportion of
selenium from each source. Movement of selenium from water indicated by two separate pathways:
bioconcentration by producers (*) and direct exposure to all trophic levels within box (**). Relative proportion of
selenium transferred between each trophic level is dependent on life history characteristics of each organism.
29
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Part 3 Effects Analysis for Freshwater Aquatic Organisms
3.1 Purpose
The purpose of this chapter is to summarize the EPA's 2016 "Aquatic Life Ambient Water
Quality Criterion for Selenium - Freshwater, 2016" which was finalized and published in June
of 2016 (EPA 822-R-16-006).4 the EPA is finalizing the national recommended 2016 selenium
aquatic life criterion as the aquatic life criterion for California. The tissue-based criterion element
concentrations were developed to protect against reproductive impairment in aquatic life due to
maternal transfer of selenium to offspring, resulting in mortality and teratogenicity, and will be
briefly summarized in this chapter. The national recommended criterion has four elements: two
fish tissue-based elements and two water column-based elements. The fish tissue elements
consist of an egg or ovary tissue final chronic value of 15.1 mg Se/kg dw, and whole body or
muscle tissue final chronic values of 8.5 and 11.3 mg Se/kg dw, respectively. The water column
elements are described in detail in Part 5 of this Technical Support Document (TSD).
3.2 Overview of Effects Analysis for Freshwater Aquatic Organisms
In the EPA's 2016 "Aquatic Life Ambient Water Quality Criterion for Selenium -
Freshwater, 2016" data were obtained primarily by search of published literature using the
EPA's public ECOTOX database. The most recent ECOTOX database search extended to July
2013; this document also reflects data either gathered or received by the EPA based on
information from the 2014 public comment period and 2014 external expert peer review of the
"External Peer Review Draft" published in May 2014, as well as information gathered based on
public comments on the 2015 draft criterion. All available, relevant, and reliable chronic toxicity
values were incorporated into the appropriate selenium AWQC tables and used to recalculate the
final chronic value (FCV), as outlined in detail in the EPA Ambient Water Quality Criteria
Guidelines. The chronic values derived from the reproductive effects (survival, deformities, and
edema) endpoints are based on the concentration of selenium in the eggs or ovary, the tissues
most directly associated with the observed effects.
Data used to derive the FCV were differentiated based on the effect (reproductive and
non-reproductive effects). Acceptable chronic toxicity data on fish reproductive effects are
4 https://www.epa.gov/sites/production/files/2016-07/documents/aauatic life awac for selenium -
freshwater 2016.pdf
30
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available for 10 fish genera. Acceptable chronic toxicity data on non-reproductive effects are
available for 7 fish genera and 3 invertebrate genera. The fish non-reproductive chronic effects
data were not used to calculate tissue criterion elements because they were more variable and
less reproducible than the data on reproductive effects. The genus sensitivity distribution is
predominantly populated with data on fish species because field evidence demonstrated that fish
communities were affected in situations having no observable change in the accompanying
diverse array of invertebrate communities. As a result, decades of aquatic toxicity research have
focused primarily on fish. The studies that have been done with invertebrates have shown them
to be somewhat more tolerant than most of the tested fish species. Table 3-1 summarizes the
effect concentrations obtained from all acceptable reproductive studies with fish.
Also, while amphibians are potentially sensitive due to physiologic similarities to fish,
effects clearly attributable to selenium are not well-known (Hopkins et al. 2000; Janz et al. 2010;
Masse et al. 2016; Unrine et al. 2007). Hopkins et al. (2000) reported that amphibian larvae at
sites receiving coal combustion wastes appear to efficiently accumulate selenium in their tissues
and have exhibited axial malformations (possibly due to selenium). In a recent laboratory
exposure, Masse et al. (2015) determined an ECio of 44.9 mg Se/kg for the African clawed frog
(Xenopus laevis) suggesting that this species is similarly sensitive to the less sensitive fish
species.
This section presents a summary of reproductive studies included in the selenium data set
and how they were used to derive the tissue criterion elements for egg-ovary, whole body and
muscle. For a detailed review of each reproductive study used to derive the criterion, see Section
3.1.1 Acceptable Studies of Fish Reproductive Effects for the Four Most Sensitive Genera in the
EPA's 2016 aquatic life criterion (ALC) document. Other reproductive and non-reproductive
studies that support the derivation of the tissue criterion are provided in Section 6 of the 2016
ALC document, Effects Characterization.
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Table 3-1. Maternal Transfer Reproductive Toxicity Studies.
Species
Reference
Exposure Route
Toxicological
Endpoint
Chronic Value
mg Se/kg dwa
SMCV
mg Se/kg dw
GMCV
mg Se/kg dw
Salve linus malma
Dolly Varden
Golder
Associates 2009
dietary and waterborne
(field: Kemess Mine
NW British Columbia)
ECio for total
deformities
56.2 E
56.2 E
56.2 E
Esox Indus
northern pike
Muscatello et
al. 2006
dietary and waterborne
(field: Saskatoon, Sask.)
EC24 larval
deformities
34.0 E
34.0 E
34.0 E
Cyprinodon macularius
desert pupfish
Besser et al.
2012
dietary and waterborne
(lab) "
Estimated EC 10 for
offspring survival
27 E
27 E
27 E
Micropterus salmoides
largemouth bass
Carolina Power
& Light 1997
dietary (lab)
EC 10 for larval
mortality &
deformity
26.3 O
26.3 O
26.3 O
Pimephales promelas
fathead minnow
Schultz and
Hermanutz
1990
dietary and waterborne
(mesocosm: Monticello)
LOEC for larval
edema and
lordosis
<25.6 Eb
NAC
NA
Oncorhynchus mykiss
rainbow trout
Holm 2002;
Holm et al.
2003, 2005
dietary and waterborne
(field: Luscar River,
Alberta)
EC 10 for skeletal
deformities
24.5 Eb
24.5 E
25.3 E
Oncorhynchus clarkii
lew i si
Westslope cutthroat trout
Rudolph et al.
2008
dietary and waterborne
(field: Clode Pond, BC)
EC 10 for alevin
mortality
24.7 E
26.2 E
Oncorhynchus clarkii
lew i si
Westslope cutthroat trout
Nautilus
Environmental
2011
dietary and waterborne
(field: Clode Pond &
Fording River, BC)
EC 10 for survival
at swim-up
27.7 E
Salmo trutta
brown trout
Formation
Environmental
2011; AECOM
2012
dietary and waterborne
(field: Lower Sage
Creek & Crow Creek,
ID)
EC 10 for larval
survival
21.0 E
21.0E
21.0 E
32
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Species
Reference
Exposure Route
Toxicological
Endpoint
Chronic Value
mg Se/kg dw'1
SMCV
mg Se/kg dw
GMCV
mg Se/kg dw
Lepomis macrochirus
bluegill
Doroshov et al.
1992
dietary (lab)
ECio larval edema
22.6 E
20.6 E
20.6 E
Lepomis macrochirus
bluegill
Coyle et al.
1993
dietary and waterborne
(lab) "
ECio for larval
survival
26.3 E
Lepomis macrochirus
bluegill
Hermanutz et
al. 1992, 1996
dietary and waterborne
(mesocosm: Monticello)
EC io for larval
edema
14.7 Ob
A cipenser transmontanus
white sturgeon
Linville 2006
dietary (lab)
EC io for combined
edema and
deformities
15.6 E
15.6E
15.6 E
E-concentration reported in egg; O-concentration reported in ovary.
SMCV-species mean chronic value; GMCV-genus mean chronic value.
a All chronic values reported in this table are based on the measured concentration of selenium in egg-ovary tissues.
b Tissue value converted from ww to dw. See U.S. FWS (2017) for conversion factors.
c SMCV not calculated due to variability in the observations among replicates in Schultz and Hermanutz (1990). The chronic
value is presented in this table to show it is in the range of selenium effect concentrations. See U.S. FWS (2017) for detail.
Also, see Appendix E of U.S EPA (2016a) for an additional study with fathead minnow.
33
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3.2.1 Fish Ess-Ovary Criterion Element Concentration
The lowest four GMCVs for fish reproductive effects as measured in eggs or ovaries are
presented below in Table 3-2. With n = 15 GMCVs (see Section 3.1.6 in U.S. EPA 2016a), the
5th percentile projection yields an egg-ovary criterion element concentration of 15.1 mg Se/kg
dw egg-ovary, lower than the most sensitive fish species tested, white sturgeon (A.
transmontanus).
Table 3-2. Four Lowest Genus Mean Chronic Values for Fish Reproductive Effects (U.S.
EPA 2016a).
Relative Sensitivity
Rank
Genus
GMCV
(mg Se/kg dw egg-ovary)
4
Oncorhynchus
25.3
3
Salmo
21.0
2
Lepomis
20.6
1
Acipenser
15.6
3.2.2 Fish Whole Body Criterion Element Concentration
Whole body reproductive chronic values were calculated directly from whole body tissue
concentrations measured in the study or by applying an egg-ovary (EO) to whole body (WB)
conversion factor (CF) described in Section 3.2.2.2 of U.S. EPA (2016a). Direct calculations
were done when whole body measurements were available in the study and the data were
amenable to an effect level determination. The final EO/WB CF applied to each taxon was
determined using a hierarchical approach based on taxonomic relatedness and is described in
Section 3.2.2 and Appendix B of U.S. EPA (2016a). The four most sensitive reproductive-effect
fish whole body GMCVs are shown in Table 3-3. Because the factors used to convert egg-ovary
to whole body concentrations vary across species, the whole body rankings differ from the egg-
ovary rankings. With n = 15 GMCVs, the 5th percentile projection yields a whole body criterion
element concentration of 8.5 mg Se/kg dw whole body, slightly lower than the most sensitive
fish species tested, white sturgeon (A. transmontanus).
34
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Table 3-3. The Lowest Four Reproductive-Effect Whole Body GMCVs.
Relative Sensitivity
Rank
Genus
GMCV
(mg Se/kg dw whole body)
4
Salmo
13.2
3
Oncorhynchus
11.6
2
Lepomis
9.9
1
Acipenser
9.2
3.2.3 Fish Muscle Criterion Element Concentration
Reproductive chronic values for muscle tissue were calculated directly from muscle
tissue concentrations measured in the study or from the egg-ovary to muscle conversion factors
(described in Section 3.2 of U.S. EPA 2016a). Direct calculations were made when muscle
measurements were available in the study and the data were amenable to an effect level
determination. The final EO/M CF applied to each taxon was determined using a hierarchical
approach based on taxonomic relatedness, consistent with the approach used to calculate EO/WB
CFs. The four most sensitive reproductive-effect fish muscle GMCVs are shown in Table 3-4.
Because the factors used to convert egg-ovary to muscle concentrations vary across species
based on empirical data, the whole body rankings differ from both the egg-ovary rankings and
the muscle rankings. With n = 15 GMCVs, the 5th percentile projection yields a muscle criterion
element concentration of 11.3 mg Se/kg dw muscle, lower than the muscle value for the most
sensitive fish species tested, white sturgeon (A. transmontanus).
Table 3-4. The Lowest Four Reproductive-Effect Fish Muscle GMCVs.
Relative Sensitivity
Rank
Genus
GMCV
(mg Se/kg dw muscle)
4
Salmo
18.5
3
Lepomis
15.9
2
Oncorhynchus
14.3
1
Acipenser
11.9
35
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Part 4 Effects Analysis for Aquatic-Dependent Wildlife
4.1 Purpose
For the derivation of this aquatic life criterion, species that rely on aquatic prey as a
major food source were considered aquatic-dependent (see Part 4.2 for more detailed definition).
This tissue-based criterion was developed to protect against the adverse effects associated with
elevated exposure to selenium to aquatic-dependent wildlife, such as mortality, altered growth,
and reproductive impairment. Birds appear to be the most sensitive aquatic-dependent taxa to
selenium exposure (Janz et al. 2010; Ohlendorf 2003), therefore the chronic tissue-based
criterion element was derived using birds. Similar to previous assessments focused on the effects
of bioaccumulative contaminants on aquatic-dependent wildlife (U.S. EPA 1995, 1997, 2011a),
the derivation of this bird egg criterion element was based on toxicity data from the most
sensitive tested bird species (mallard), as this approach is expected to be protective of aquatic-
dependent wildlife including endangered species living in California. The tissue-based criterion
element was then translated to a protective water concentration, considering the different diets
and other life history traits of individual avian species. The resulting water concentration is
approximately equal to the chronic water column based criterion element for aquatic life (Part
5.5.2), which demonstrates that the chronic water column based criterion for aquatic life is also
protective of aquatic-dependent wildlife.
4.2 Chronic Toxicity to Aquatic-Dependent Wildlife
All available data relating to the chronic toxicological effects of selenium on aquatic-
dependent wildlife were considered in the derivation of this selenium criterion for the state of
California. Data meeting the quality objectives and test requirements that were utilized in
deriving this criterion for aquatic-dependent wildlife are presented in Table 4-1.
Aquatic-dependent wildlife data considered for inclusion in this California selenium
criterion were obtained from published literature reports on chronic exposures of selenium that
were associated with effects on mortality, growth, and/or reproduction. This set of published
literature was identified by both the EPA's public ECOTOX database and additional literature
searches. Studies with dietary and/or maternal transfer selenium exposures were considered for
possible inclusion. In developing this selenium aquatic-dependent wildlife criterion for the state
of California, only taxa that depend on aquatic prey (e.g., fish and emergent aquatic insects) as a
36
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major food source were considered aquatic-dependent. The dietary composition of the taxa
considered in this criterion consisted of 75% or greater aquatic prey, including fish, aquatic
invertebrates, amphibians, and other aquatic-dependent wildlife (birds). Additionally, studies
utilizing taxa that are not considered aquatic-dependent (e.g., members of the order Galliformes
such as chickens and pheasant) were not considered for possible inclusion unless the taxa could
be a surrogate for an aquatic-dependent species within the same or closely related order (e.g.,
studies focused on American kestrel were included because other members of this order such as
peregrine falcon are aquatic-dependent). Lastly, only studies that utilized organic selenium, such
as selenomethionine, were considered for possible inclusion. Selenomethionine has been shown
to be highly toxic to birds and appears to be the chemical form most likely to bioaccumulate in
tissues including bird eggs (Heinz et al. 1987; Hoffman and Heinz 1988), and therefore is
important to consider in evaluating potential risks from natural exposures experienced by wild
birds (Ohlendorf and Heinz 2011). Results based on dosing with selenite and/or selenate were
not utilized in the derivation of this criterion due to differences in toxicity when compared to
organic selenides (Heinz et al. 1987; Hoffman and Heinz 1988).
The studies meeting these inclusion criteria were screened for data quality by the EPA
OW generally as described by Stephan et al. (1985) in the 1985 Guidelines and the EPA OW's
Open Literature Standard Operating Procedure (SOP) (U.S. EPA 2024b). These data quality
reviews ensured the studies used to derive the criterion element were scientifically robust. These
toxicity data were further screened to ensure that the observed effects could be primarily
attributed to exposure to selenium. Both controlled laboratory experiments and field studies were
included. When available, measured selenium concentrations were used; however, for several
studies measured dietary selenium concentrations were not reported, and nominal concentrations
were utilized if a dose-response relationship was observed in another media (e.g., blood or eggs).
The studies meeting the inclusion criteria described above were used to derive a
reproductive effect-based ECio, which is the basis for this aquatic-dependent wildlife criterion
element for the state of California. As discussed in Part 2.7 above, due to the bioaccumulative
nature of selenium and the dietary pathway of exposure, the derivation of the criterion was based
on an effect concentration that impacted a small percentage of the study organisms (e.g., a 10%
effect concentration [ECio]; U.S. EPA 2016a).
37
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4.2.1 Summary of Selenium Reproductive Toxicity Studies Used to Derive the Aquatic-
Dependent Wildlife Criterion
Data for chronic selenium toxicity were available for eleven bird species, representing
nine families and six orders. Mallard (Anasplatyrhynchos) was the most sensitive species tested
and hatchability was consistently the most sensitive endpoint. In contrast, red-winged blackbird
(Agelaiusphoeniceus) appears to be the least sensitive species to selenium toxicity data in the
current literature, with Harding (2008) reporting adverse effects on hatchability at selenium egg
concentrations of approximately 22.0 mg/kg dw for this species, (see Part 4.6.1 for additional
details).
Six of the mallard toxicity studies described below (Heinz et al. 1987; Heinz et al. 1989;
Heinz and Hoffman 1996; Heinz and Hoffman 1998; Stanley et al. 1994; Stanley et al. 1996) had
a similar test design in which seleno-DL-methionine was fed to breeding pairs in artificial diets.
Data from three of these studies (Heinz et al. 1987; Heinz et al. 1989; Stanley et al. 1996) were
combined into a single concentration-response relationship for hatchability versus selenium
concentrations in eggs. This concentration-response relationship was used to derive the aquatic-
dependent wildlife criterion (see Part 4.3). The other three studies (Heinz and Hoffman 1996 and
1998; Stanley et al. 1994) were not included in the combined dataset mentioned above and were
not used quantitatively to derive the aquatic-dependent wildlife criterion. See Part 4.3 below for
details on the qualitative use of these studies. A summary of the studies including dietary
concentrations, control hatchability, and observed effects is in Part 4.6.1.
Below is a brief description of the three mallard toxicity studies used in the derivation of
the present criterion for the state of California, including a synopsis of the experimental design,
test duration, relevant test endpoints, and other critical information. Data are summarized in
Table 4-1, and more detailed study summaries are included in Table A-l.
All three mallard toxicity studies used to derive the bird egg criterion (Heinz et al. 1987,
1989; Stanley et al. 1996) were conducted at the Patuxent Environmental Science Center, Laurel,
Maryland under similar test conditions. Each study exposed breeding pairs of mallards (between
one and two years old) to a commercial diet supplemented with varying concentrations (between
1 and 16 mg/kg) of selenium as seleno-DL-methionine (Table 4-1). To delay the onset of egg
laying, females were kept in indoor pens for three to four weeks at eight hours of light per day.
The females were fed their assigned diet (control or selenium treated) prior to being paired with
males and placed in outdoor pens (1 m2). The dietary treatments and the number of breeding
38
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pairs per treatment for each study are listed in Table 4-1. Nests were monitored daily, eggs were
numbered sequentially, and either the eighth (Heinz et al. 1989; Stanley et al. 1996) or tenth
(Heinz et al. 1987) egg was collected to measure whole egg weight, length, width; shell weight
and thickness; and weight of egg contents. The contents of each of these eggs were saved for
selenium analyses. Additional eggs were collected throughout the breeding period from one extra
breeding pair by Heinz et al. (1987), as the first, fifth, ninth, thirteenth, seventeenth, twenty-first,
twenty-fifth, twenty-ninth, and thirty-third eggs, and from three extra breeding pairs by Heinz et
al. (1989) as the first, fourth, seventh, tenth, thirteenth, and sixteenth eggs to demonstrate that
selenium concentrations varied little across the clutch. In Stanley et al. (1996), females incubated
their own clutch of < 20 eggs. In Heinz et al. (1987, 1989) eggs were selected for incubation,
labeled according to pen, and stored at 10°C, until placement in an incubator maintained at
37.6°C and at a relative humidity of 60-68%.
In addition to selenium, Stanley et al. (1996), included dietary treatments that exposed the
birds to boron. To avoid complications of potential interactions with boron, only those treatments
to which selenium alone was added to the diet were included in the effects analysis for this study.
Heinz et al. (1987) and Heinz et al. (1989) included dietary treatments with chemical
forms of selenium (Se) other than seleno-DL-methionine. Heinz et al. (1987) included dietary
treatments of selenium as sodium selenite at 1, 5, 10, 25, and 100 mg/kg. Heinz et al. (1989)
included a dietary treatment of 16 mg/kg selenium as seleno-DL-cystine. As stated in the
previous section, the chemical form of selenium determined to be suitable for the effects analysis
was selenomethionine because of its toxicity and bioavailability. An example of its greater
bioavailability was observed in Heinz et al. (1987) where the dietary treatment of 10 mg/kg
selenium as selenite resulted in 0.53 mg Se/kg wet weight (ww) in eggs, whereas 10 mg/kg
selenium as selenomethionine yielded 4.6 mg Se/kg ww in eggs. Selenomethionine was also
found to be much more bioavailable than selenocystine in Heinz et al. (1989), where 16 mg/kg
dietary treatments of both forms of selenium resulted in the respective egg selenium
concentrations of 18 and 0.57 mg/kg ww. Additionally, eggs collected from extra breeding pairs
fed the selenium treated diets in Heinz et al. (1987) and Heinz et al. (1989) showed little intra-
clutch variability in measured selenium concentrations.
These three mallard toxicity studies looked at endpoints such as mortality and body
weight in the parents and offspring as well as hatchability, egg weight, embryo deformity,
39
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fertility, and growth. The addition of 10 mg/kg selenium as selenomethionine to the diet did not
have any effects on adult survival or weight at sacrifice (mean weights of 1,120 g for males and
1,114 g for females) compared to those in the control group (mean weights of 1,046 g for males
and 1,141 g for females) in Heinz et al. (1987). And while the percent hatch of fertile eggs and
duckling weight at twenty-one days old were reduced in the selenium treatment group (30.9%
hatch and 297 g, respectively) compared to the control group (65.7% hatch and 371 g,
respectively), these reductions were not statistically significantly different from controls.
However, an 18.3% increase in abnormal embryos was observed in the selenium treatment group
as were reductions in the percentage of healthy hatchlings surviving twenty-one days of age
(50%>) when compared to controls (98.7%>).
Similarly, Heinz et al. (1989) did not observe any effects on adult survival or signs of
selenium intoxication. The study authors reported statistically significant reductions in percent
hatch of fertile eggs in the 16 mg/kg selenium dietary treatment group (2.2%> hatch of fertile
eggs) and a statistically significant reduction in nestling weight in the 8 mg/kg selenium dietary
treatment group (58 g) compared to controls (59.6%> hatch of fertile eggs and 72 g, respectively).
Of embryos that did not hatch, 6.8 and 67,9%> contained malformed embryos in the 8 and 16
mg/kg selenium treatment groups, respectively, compared to 0.6%> in the control group. The
results of the deformity analysis in the Heinz et al. (1987, 1989) were reported and discussed in
Hoffman and Heinz (1988). For a summary of the deformity findings reported by Hoffman and
Heinz (1988), see Part 4.6.1.
Lastly, Stanley et al. (1996) did not observe any effects of selenium on adult weight.
However, reductions in fourteen-day old duckling weight were observed in the 7 mg/kg selenium
treatment group (mean weight of 130.1 g) compared to controls (mean weight of 145.1 g), but
these reductions were not statistically significant. A statistically significant decrease in hatching
success was observed in the 7 mg/kg selenium treatment group (41%> hatch) compared to the
control (62% hatch).
Hatchability was the reproductive endpoint that was consistently observed and most
sensitive in all three studies (Heinz et al. 1987, 1989; Stanley et al. 1996). Duckling weight,
growth, and production were all equally sensitive to hatching success in Stanley et al. (1996),
and the number of normal hatchlings and nestling weight were also similar in sensitivity to
hatchability in Heinz et al. (1989). Therefore, because hatchability was one of the most sensitive
40
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endpoints reported, was consistently observed and significantly different from controls in two of
the three studies Heinz et al. 1989 and Stanley et al. 1996), and was comparable across all three
studies, the bird egg criterion element was based on hatchability data reported by Heinz et al.
(1987, 1989) and Stanley et al. (1996).
41
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Table 4-1. Effect of Dietary Selenium (as Selenomethionine) on Hatchability of Mallard Eggs and the Associated
Concentration of Selenium in Eggs.
Modified from Table 17.1 in Ohlendorf (2003).
Diet Se
%
mg/kga
N
Egg
Hatchability
Percent
Egg Se,
Nominal
(hens)
Hatchability %b
as % Control
Moisture
mg/kg dw
Reference
Control
11
64.4
100
71
0.17
Heinz et al. 1987
10
5
34.6
54
71
15.9
Heinz et al. 1987
Control
32
57.3
100
70
0.60
Heinz et al. 1989
1
15
65.0
114
70
2.77
Heinz et al. 1989
2
15
59.6
104
70
5.33
Heinz et al. 1989
4
15
54.3
95
70
11.3
Heinz et al. 1989
8
15
42.3
74
70
36.7
Heinz et al. 1989
16
9
7.4*
13
70
60.0
Heinz et al. 1989
Control
33
62
100
71
0.93
Stanley et al. 1996
3.5
29
61
98
71
12.1
Stanley et al. 1996
7
34
41*
66
71
24.5
Stanley et al. 1996
a Selenium concentrations in diet are presented as nominal. Control diets typically contained 0.4 mg Se/kg dw.
b Asterisks indicate hatchability determined by respective authors to be significantly different than control following post hoc means
comparison testing.
42
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4.3 Derivation of Bird Egg Criterion Element
The data outlined in Table 4-1 from the three mallard toxicity studies summarized above in Part
4.2.1 (Heinz et al. 1987, 1989; Stanley et al. 1996) were analyzed using the statistical software
program R (version 3.4.3) and the associated dose-response curve (drc) package to calculate a
bird egg ECio of 11.2 mg Se/kg dw with a lower 95% confidence limit of 7.4 mg Se/kg dw and a
95% upper confidence limit of 15.0 mg Se/kg dw (Figure 4-1). All parameters in this model
yielded significant p-values (P < 0.05). This selenium ECio was derived from a four-parameter
model (Equation 4-1), and each observation was weighted according to sample size based on the
number of eggs. The bird egg ECio is the basis for the aquatic-dependent wildlife criterion
element.
, . d - c
TC(x) - c + ^ + eXpb(log(x) e))
(Equation 4-1)
where:
X
= Selenium concentration
7t(x)
= Probability egg hatches at concentration x
b
= Slope of the dose response curve at ECso
c
= Lower horizontal asymptote
d
= Upper horizontal asymptote
e
= ECso concentration
The approach used to derive the bird egg ECio of 11.2 mg Se/kg dw was similar to the
meta-analysis conducted by Ohlendorf (2003) described in detail in Part 4.4 below. The meta-
analysis by Ohlendorf (2003) included data from three mallard toxicity studies not included here
by the EPA (Heinz and Hoffman 1996, 1998; Stanley et al. 1994) to calculate a selenium mallard
ECio of 12.5 mg Se/kg dw based on hatchability. The Ohlendorf (2003) bird egg ECio of 12.5 mg
Se/kg dw serves as the basis for the selenium standard in the Great Salt Lake of Utah (CH2M
Hill 2008). Two of the three mallard toxicity studies used in Ohlendorf (2003) but not in this
meta-analysis had control hatchability below 52% (Heinz and Hoffman 1996, 1998) and
43
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therefore did not meet the EPA's test guidelines (U.S. EPA 2012). In contrast to Ohlendorf
(2003), data in this California selenium criterion analysis were not control normalized prior to
analysis, and a Fisher's exact test was performed to determine if statistically significant
differences existed in hatchability across the control groups. As a result, the data from Stanley et
al. (1994) were removed from the meta-analysis because the high control hatchability in this
study was determined to be statistically different from the other control groups in the meta-
analysis (91.4% in Stanley at al. 1994, compared to 57-64.4% in the remaining studies) and
resulted in a poor goodness of fit. The bird egg ECio derived from the remaining three studies
(Heinz et al. 1987, 1989; Stanley et al. 1996) was 11.2 mg Se/kg dw.
In addition to removing three of the studies for reasons described above, the data used to
derive the ECio of 11.2 mg Se/kg dw here differ from those analyzed by Ohlendorf (2003) in the
following respects. First, selenium concentrations used in the ECio calculation were converted
from wet weight to dry weight using whole egg percent moisture contents provided by the
authors in the respective studies, in contrast to the average value of 70% whole egg moisture
content used by Ohlendorf (2003). The difference was negligible. Second, for data from Heinz et
al. (1987) and Heinz et al. (1989), the arithmetic mean percent hatchabilities were determined
from raw data provided by the lead author instead of mean concentrations reported in the
respective publications in order to be consistent with the remaining study. Mean hatchabilities
reported in Heinz et al. (1987) and Heinz et al. (1989) had been back-calculated from arcsine
square root transformed values, which were slightly different than the original measured values
(G. Heinz, pers. comm.).
The modeling approach used to derive the bird egg ECio value of 11.2 mg Se/kg dw for
this selenium aquatic-dependent wildlife criterion was selected because it is conceptually similar
to the approach used by Ohlendorf (2003), which is a widely accepted ECio for selenium and
serves as the basis for the selenium standard in the Great Salt Lake of Utah (CH2M Hill 2008).
The bird egg ECio of 11.2 mg/kg dw calculated for this aquatic-dependent wildlife selenium
criterion is considered preferable to the Ohlendorf (2003) ECio because the corrections to the
dataset described above ensure that the EPA's data quality guidelines are met and that the
observed effects on egg hatchability reflect selenium exposure.
44
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1
Se Concentration (mg/kg dw)
10
Figure 4-1. Logistic regression model of mallard hatchability in relation to egg selenium
concentrations.
Mallard egg ECio for selenium of 11.2 mg Se/kg dw. Gray shaded area surrounding the fitted
curve represents 95% confidence interval.
4.4 Previously Calculated Selenium Thresholds (as ECm) for Mallard Hatchability
Meta-Analysis of Six Mallard Toxicity Studies - Ohlendorf (2003)
As mentioned above in Part 4.3, Ohlendorf (2003) calculated an egg ECio of 12.5 mg
Se/kg dw for mallard egg hatchability based on a meta-analysis of six different laboratory studies
using logistic regression (Heinz and Hoffman 1996, 1998; Heinz et al. 1987, 1989; Stanley et al.
1994, 1996). Data from the six studies were normalized to their respective controls and
combined in a single dataset prior to analysis. The resulting ECio for mallard egg hatchability
was 12.5 mg Se/kg dw, with a 5% lower confidence limit of 6.4 mg Se/kg dw and a 95% upper
confidence limit of 16.5 mg Se/kg dw (Figure 4-2). At around the same time, Adams et al.
(2003) using five of the above six studies (excluding Heinz et al. 1987), had calculated ECios in
45
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the range of 12-15 mg Se/kg dw (rounded to two digits) using logit, probit, and piece-wise linear
curves.
Se in Eggs (mg/kg, dry wt.)
Figure 4-2. Mallard egg hatchability as a function of selenium concentration in eggs.
Source is Figure 17.2 from Ohlendorf (2003).
The data were normalized to their respective control hatchability values. LCL = lower
confidence limit. UCL = upper confidence limit.
2011 EPA Reanalysis of the Six Mallard Toxicity Studies
The EPA performed an independent evaluation of the mallard data used in the Ohlendorf
(2003) analysis during its review of the selenium standard for the Great Salt Lake in Utah (U.S.
EPA 201 la; CH2M FTill 2008). The values used in the U.S. EPA (201 la) reanalysis were
adjusted from those in Ohlendorf (2003) after accounting for author-reported percent moisture
content in eggs, potential arsenic exposure in the Stanley et al. (1994) treatment mean, and
differences in mean percent hatchabilities from Heinz et al. (1987, 1989) resulting from back
calculation of arcsine square root transformed values as described in Part 4.3. Collectively, these
adjustments had a minor influence on the results but improved the accuracy of the dataset. In
U.S. EPA (201 la), three ECio values were calculated using different models (tolerance
distribution and nonlinear regression models) and data (all six studies vs. only the four studies
with control hatchability greater than 52%). The egg ECio values were calculated using the U.S.
EPA Toxicity Relationship Analysis Program (TRAP; U.S. EPA 201 lb) and ranged from 9.7-
46
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12.7 mg Se/kg dw. The concentration range of these tests supported the results of the Ohlendorf
(2003) analysis, which serves as the basis for the Great Salt Lake selenium standard (CH2M Hill
2008).
The first egg ECio was calculated from the six study Ohlendorf (2003) mallard dataset
without normalizing egg hatchability to controls. Some authors have suggested that control
normalization is inappropriate because control responses themselves contain variability, and that
control normalization effectively removes this estimation error from the control values (OECD
2006). The resulting egg ECio was 12.3 mg Se/kg dw using a tolerance distribution model
(Figure 4-3).
Log of Se (mg/kg) in Eggs
Figure 4-3. Mallard egg hatchability in the six studies, fitted using a tolerance distribution
model, without normalization to control values. Source is Figure 2 in U.S. EPA (201 la).
Confidence intervals surrounding the ECio were not included in the source document.
A second egg ECio with no control normalization was calculated from the combined
mallard dataset after excluding the two studies with low (<52%) control hatchability (Heinz and
Hoffman 1996, 1998). The resulting egg ECio was 12.7 mg Se/kg dw and was also calculated
using a tolerance distribution model.
In a third egg ECio calculation, the EPA derived an ECio for all six mallard studies after
first normalizing egg hatchability from each study to their respective controls. The EPA
47
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calculated an egg ECio of 9.7 mg Se/kg dw using a logistic nonlinear regression model. Although
this estimate of an egg ECio is different than the 12.5 mg Se/kg dw in Ohlendorf (2003), the EPA
could find no scientific basis for concluding that a logistic nonlinear regression fit was more or
less appropriate than a tolerance distribution fit. In the absence of any meaningful scientific
justification to prefer one approach over the other, the different values derived from the
application of these two models to the same data are both scientifically defensible.
The EPA further evaluated the effects of selenium in egg tissue below the ECio of 12.5
mg Se/kg dw. Figure 4-4 shows the percent hatch in the six control treatments, and the selenium
exposed treatments for those studies (U.S. EPA 201 la). The egg ECio of 12.5 mg Se/kg dw is
represented by the vertical line. Hatchability at all treatment concentrations less than 12.5 mg
Se/kg dw are within the range of the controls and the lower 95% confidence range of the control
mean, which is shown by the lower horizontal dashed line. By contrast, all treatment
concentrations greater than the egg ECio of 12.5 mg Se/kg dw yielded hatchability below the
lower confidence bound for the control mean and below the hatchability of any control. These
data suggest that the hatchability associated with the egg ECio of 12.5 mg Se/kg dw was
statistically similar to the that of the control mean, and that selenium concentrations up to 12.5
mg Se/kg dw would not be expected lead to additional reductions in hatchability beyond natural
conditions based on the limited available data.
48
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100 -|
90 -
SO -
70
J=
o
60
CO
X
50 -
40 -
30 -
20 -
10 -
0 -I
controls
o
o
1
O
2
O
3
+
4
~
5
-
6
Criterion
Control Avg
Confid range
0
0.1
100
1 10
Egg Se (mg/kg dw)
Figure 4-4. Mallard percent hatch v. egg concentration for six studies values.
Source is Figure 3 of U.S. EPA (201 la).
Raw data without normalization to control values.
1 = Heinz et al. (1989); 2 = Heinz et al. (1987); 3 = Stanley et al. (1996); 4 = Stanley et al.
(1994); 5 = Heinz and Hoffman (1996); 6 = Heinz and Hoffman (1998).
For this current aquatic-dependent wildlife selenium criterion for the state of California,
the EPA again reanalyzed the mallard toxicity data to calculate an egg ECio value for selenium
from the dataset described above in Part 4.3 based on the three mallard toxicity studies that met
the EPA data quality guidelines and did not have outliers when combined into a single dataset
(Heinz et al. 1987, 1989; Stanley et al. 1996). The selenium egg ECio of 11.2 mg Se/kg dw is
similar to those calculated in the 2011 EPA reanalysis of the mallard toxicity studies detailed
above.
A notable difference is regarding the model used to calculate the ECio value. As noted
above, the ECio values calculated in the 2011 EPA reanalysis of the mallard toxicity studies were
calculated with the use of TRAP (U.S. EPA 201 lb). However, TRAP was not designed to work
with data pooled from multiple studies. Therefore, in this current reanalysis and derivation of the
selenium aquatic-dependent wildlife criterion for the state of California, the EPA used a
generalized linear model to calculate an egg ECio of 11.2 mg Se/kg dw, which is believed to be a
better statistical fit to the mallard toxicity data compared to earlier meta-analyses.
49
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MallardBiphasic Dose-Response Analysis Study - Beckon et al. (2008)
Beckon et al. (2008) applied biphasic modeling in their description of the biphasic dose-
response behavior of selenium in biological samples. A biphasic model has both a rising and
falling limb and is applied to datasets where both low and high concentrations of a substance can
negatively impact an organism. Beckon et al. (2008) calculated an egg ECio of 7.7 mg Se/kg dw
for reduced egg hatchability when applying a biphasic model to the mallard egg hatchability data
reported by Heinz et al. (1989).5 Beckon et al. (2008) fit these same data to two other models, a
conventional log-logistic concentration-response model (with an egg ECio of 28.6 mg Se/kg dw),
and a second model with a rising and falling limb, the Brain-Cousens (Brain and Cousens 1989)
model (with an egg ECio of 3.4 mg Se/kg dw). Beckon et al. (2008) note that the Brain-Cousens
model provides a poor fit, and that the conventional log-logistic model is inappropriate if the
relationship between selenium and hatchability is biphasic.
The EPA has previously evaluated the biphasic relationship between selenium and egg
hatchability during its review of the selenium standard for the Great Salt Lake in Utah (CH2M
Hill 2008; U.S. EPA 201 la) and concluded that the relationship cannot be modeled as biphasic.
The six mallard toxicity studies were not designed to study selenium deficiency and included no
treatment that was intentionally selenium deficient. Consequently, implicit in fitting the biphasic
model to these data is a belief that the control diet (i.e., the culture diet) was unintentionally
deficient. If unintentionally deficient in selenium, there is little reason to suspect the deficiency
was limited to selenium - several other nutrients may have been involved. This implies that the
responses at all treatment levels could have been confounded by multiple stresses involving such
deficiencies (U.S. EPA 201 la). In addition, control hatchability among the six mallard toxicity
studies was high. If data from the six mallard studies are combined and fit to a biphasic model,
and the ECio for selenium excess and deficiency are calculated relative to the average control
hatchability of the six studies, the ECio for excess selenium would be 11.8 mg Se/kg dw, which
is within 10% of the Ohlendorf (2003) ECio of 12.5 mg Se/kg dw (U.S. EPA 201 la), and is
similar to the current calculated ECio of 11.2 mg Se /kg dw.
5 The ECio for the biphasic model is reported as 7.7 mg/kg in the text of Beckon et al. (2008) and as 7.3 in Figure 5
of Beckon etal. (2008).
50
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Table 4-2. Previously Calculated and Current Selenium ECio values for Mallard
Hatchability.
Common
Name
Scientific
Name
Toxicological
Endpoint3
Mean Egg Se
Effect
Threshold
(mg Se/kg egg
dw)
Reference
mallard
Anas
platyrhynchos
ECios for post-hatch
survival based on control
normalized results of
five laboratory studies,
using various curve
shapes
12 - 15
Adams et al. (2003)
mallard
Anas
platyrhynchos
EC 10 for egg hatchability
based on control
normalized results of six
laboratory studies with
mallards, using logistic
regression analysis
12.5
(95% CI =
6.4 - 16.5)
Ohlendorf (2003)
mallard
Anas
platyrhynchos
EC 10 for egg hatchability
based on results of six
laboratory studies with
mallards, using TRAP
12.3
U.S. EPA (2011a)
mallard
Anas
platyrhynchos
EC 10 for egg hatchability
based on results of four
laboratory studies with
mallards, using TRAP
12.7
U.S. EPA (2011a)
mallard
Anas
platyrhynchos
EC 10 for egg hatchability
based on control
normalized results of six
laboratory studies with
mallards, using TRAP
9.7
U.S. EPA (2011a)
mallard
Anas
platyrhynchos
EC 10 for egg hatchability
based on results of Heinz
et al. (1989), assuming
hormetic effects;
reanalysis using biphasic
model regression
7.7
Beckon et al. (2008)
51
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Common
Name
Scientific
Name
Toxicological
Endpoint3
Mean Egg Se
Effect
Threshold
(mg Se/kg egg
dw)
Reference
mallard
Anas
platyrhynchos
ECio for egg hatchability
based on results of three
mallard studies (Heinz et
al. 1987, 1989; Stanley et
al. 1996) using logistic
regression analysis. This
model serves as the basis
for the egg tissue
criterion element.
11.2
Part 4.3 of this
Current Draft
Document
a An effect concentration (EC) can be specified at different levels of effect and :
or different
endpoints. ECs are the concentrations of selenium that adversely affect a certain percentage of the
test organisms, i.e., an ECio level affects 10% of the test organisms.
TRAP is the Toxicity Relationship Analysis Program, U.S. EPA (201 lb).
4.5 Chronic Egg Selenium Criterion Element Concentration
Table 4-2 shows the effect concentrations obtained from maternal transfer reproductive
toxicity studies conducted with mallards. Mallard toxicity studies form the basis for the most
reliable bird thresholds to date. Based on an analysis described above in Part 4.3 of three mallard
toxicity studies meeting the EPA's data quality guidelines (summarized in Part 4.2), a selenium
egg EC io of 11.2 mg Se/kg dw was derived for the most sensitive bird species studied and was
based on the most sensitive endpoint (hatchability) measured. The EPA is finalizing a mallard
egg EC io of 11.2 mg Se/kg dw as an aquatic-dependent wildlife criterion for protecting aquatic-
dependent birds. As selenium concentrations appear to vary little within a single clutch and thus
are not influenced by laying sequence (DeVink et al. 2008; Heinz et al. 1987, 1989; Weech et al.
2012), a sampling effort to measure egg selenium concentrations would not be dependent on egg
laying sequence to reduce differences caused by intra-clutch variability. As discussed in Part 2.7,
an EC io was determined to be an appropriate effect concentration for tissue-based criteria given
the nature of exposure and effects for this bioaccumulative chemical.
In Part 5 of this TSD, the EPA translated the mallard egg ECio value of 11.2 mg Se/kg
dw to a selenium water column concentration based on the diets of a number of bird species to
provide an translation from bird egg to water that is equivalent to the previously derived 2016
52
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national aquatic life selenium criterion. In this analysis, the EPA found that the translated
selenium water column concentration for aquatic-dependent wildlife is approximately equal to
the 2016 national aquatic life selenium water column criterion element of 1.5 |ig/L for lentic and
3.1 |ig/L for lotic systems.
4.6 Summary of Selenium Toxicology Studies Used Qualitatively in the Criterion
Derivation
Several studies were identified as either not meeting the EPA's data quality guidelines for
inclusion in the criterion calculations or would not support the derivation of an ECio. However,
these studies showed similar effects and ranges of toxicity to the studies presented in Part 4.2.1
above and demonstrate that mallard is the most sensitive species to selenium exposure. To
provide additional evidence of the observed toxicity and effects of selenium, including the
relative sensitivity of the bird species studied compared to mallards, these studies are presented
below, divided into those with reproductive effects and non-reproductive effects and grouped by
order. NOEC and LOEC values are provided in several of the following studies as representative
effect concentrations for comparison to the ECio value calculated for mallards. The
NOEC/LOEC values were not used in a quantitative analysis toward the determination of the
final chronic value for aquatic-dependent birds. Summary tables for the qualitative reproductive
and non-reproductive studies described below are included in Appendix A.
4.6.1 Reproductive Studies Used Qualitatively in the Criterion Derivation
Anseriformes (Ducks, Geese, and Swans)
Hoffman and Heinz (1988) primarily described deformity endpoints for mallards that
were measured, but not reported, in two separate studies (Heinz et al. 1987, 1989) described in
Part 4.2.1 above. Both studies were conducted at the Patuxent Environmental Science Center,
Laurel, Maryland, where breeding pairs of mallards were exposed to a commercial feed diet
supplemented with different chemical forms of selenium (sodium selenite and seleno-DL-
methionine). Heinz et al. (1987) divided mallard breeding pairs into six groups: one control
group of eleven pairs, ten pairs fed 1, 5, 10, or 25 mg/kg selenium as sodium selenite, and five
pairs fed 10 mg/kg selenium as seleno-DL-methionine. Corresponding selenium concentrations
in eggs by group were 0.17, 0.10, 0.60, 1.77, 4.3, and 15.3 mg Se/kg dw. Heinz et al. (1989)
divided mallard breeding pairs into six groups: one control group of thirty-five pairs, fifteen pairs
fed 1, 2, 4, or 8 mg/kg selenium as seleno-DL-methionine, and ten pairs fed 16 mg/kg selenium
53
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as seleno-DL-methionine. Corresponding selenium concentrations in eggs by group were 0.60,
2.77, 5.33, 11.3, 36.7, and 60.0 mg Se/kg dw. In Heinz et al. (1987), the percentage of abnormal
embryos and day one to seven-day embryo mortality was significantly higher in the 10 mg/kg
sodium selenite treatment relative to controls. Abnormal embryos included all individuals with
any physical malformations, as well as edema and stunted growth, and are considered more
sensitive than deformity endpoints. Embryo mortality was significant when measured for all eggs
per treatment, but not for eggs per nest per treatment. In Heinz et al. (1989), the percentage of
malformed embryos was significantly higher in the 8 mg/kg seleno-DL-methionine treatment
relative to controls. The authors concluded that comparable dietary concentrations of seleno-DL-
methionine were more toxic than sodium selenite, most likely because seleno-DL-methionine is
more readily incorporated into tissues and transferred to offspring. The seleno-DL-methionine
test was found to be to be acceptable during data quality review. Therefore, this test could be
considered for quantitative use. However, this endpoint (% malformed embryos) was generally
less sensitive (LOEC reported here as 36.7 mg Se/kg dw) than the most sensitive endpoint of
hatchabililty (LOECs measured in eggs of 15.3, 60.0 and 24.48 mg Se/kg dw, respectively) that
was reported in other papers (Heinz et al. 1987, 1989 and Stanley et al. 1996) and that was used
quantitatively in the derivation of the mallard ECio of 11.2 mg Se/kg dw). Therefore, the data
presented in Hoffman and Heinz (1988) was not used to estimate an ECio for hatchability (as the
endpoints were different and the hatchability endpoint was measured for this study but reported
in separate publications) or in the derivation of the criteria.
Heinz and Fitzgerald (1993a) exposed forty breeding pairs of mallards to 15 mg Se/kg
ww (16.7 mg/kg dw) dietary selenium, as selenomethionine, for twenty-one weeks through
winter until soon after the first females began laying eggs, at which time dosing ceased. Controls
consisted of twenty breeding pairs. Treatment group females had statistically significant lower
body weight at pairing and took longer to lay the first egg after pairing. The hatching success of
the first eggs laid by selenium treated females was statistically significantly reduced (44% after
one week off selenium diet and 50% after two weeks off selenium diet) compared to controls
(70.5%) throughout experiment) and four of these early eggs contained deformed embryos.
Selenium concentrations in the series of eggs subsequently laid decreased over time following
the end of the exposure period. Two weeks after selenium treatments ceased reproductive
success in the selenium treatment group returned to levels comparable to controls. The authors
54
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concluded that for birds migrating from contaminated to uncontaminated areas, reproductive
performance would return to control levels within about two weeks after leaving the
contaminated site. For this study, based on the single treatment level and its effect on delaying
onset of egg-laying, the LOEC would be 15 mg Se/kg ww or 16.7 mg Se/kg dw in diet. This test
was of acceptable data quality and was considered for quantitative use. However, the authors
only reported dietary concentrations and did not measure or report the concentration in eggs.
Thus, without the egg concentrations this study could not be included to estimate an ECio for
mallard egg hatchability. Alternatively, this study indicates that the three studies used to estimate
an ECio for hatchability in mallard are protective since the dietary, author-reported LOECs are in
line (ranging between 7 and 16 mg Se/kg ww) with the dietary, author reported LOEC of 15 mg
Se/kg ww for this study.
Heinz and Hoffman (1996) fed ten breeding pairs of adult mallards a control diet and fed
fifteen breeding pairs diets containing 10 mg/kg selenium as either seleno-DL-methionine,
seleno-L-methionine or selenized yeast, respectively for approximately fourteen days. The
average selenium concentrations in the eighth egg of each clutch were 0.41, 9.2, 8.9, 6.6 mg
Se/kg ww for the control, seleno-DL-methionine, seleno-L-methionine, and selenized yeast
treatments, respectively. No effects on adult mallards were observed. Several endpoints showed
significant differences between the selenium treatments and the control including percent hatch
of fertile eggs and the number of six-day old ducklings produced per hen. For instance, hatching
of fertile eggs was significantly lower for females in both selenomethionine treatments (7.6%
and 6.4% for seleno-DL-methionine and seleno-L-methionine, respectively) compared to
controls (41.3%). Also, the number of six-day old ducklings produced per female was
significantly lower for mallards fed seleno-DL-methionine (0.47 ducklings/female) and seleno-
L-methionine (0.13 ducklings/female) compared to controls (6.10 ducklings/female). However,
no significant differences in reproductive endpoints were observed between the two forms of
selenomethionine. As noted above, the data from this study were not used in the derivation of the
bird egg criterion as test validity requirements in the EPA's Ecological Effects Test Guidelines
for Avian Reproduction Tests (U.S. EPA 2012) states that control hatchability should be greater
than 52% in mallard toxicity studies and the authors of this study report that the control
hatchability was 41.3% (Heinz and Hoffman 1996). The results of this study do provide
55
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qualitative support of the bird egg criterion in that the percent hatch of fertile eggs for the two
selenium treatments fall within the dose response curve for egg selenium (see Part 4.3).
In a separate study, Heinz and Hoffman (1998) fed adult mallard breeding pairs a control
diet or diets containing 10 mg/kg selenium, 10 mg/kg mercury, or 10 mg/kg mercury plus 10
mg/kg selenium, respectively, for fifty-six to seventy days. Average selenium concentrations
measured in the eleventh egg from each clutch was 0.35 mg Se/kg ww for controls, and 7.6,
0.39, 9.3 mg Se/kg ww for each of the three treatment groups listed above, respectively. No
effects were observed on adults in the selenium treatment group of 10 mg/kg selenium in diet
with 7.6 mg Se /kg ww in the eleventh egg. Also, no significant differences in the number of
days between eggs laid, percentage of eggs laid outside the nest box, whole egg weight, egg-shell
thickness, or fertility of eggs were observed among the treatments. The combination of 10 mg/kg
mercury and 10 mg/kg selenium in the diet had greater toxic effects on hatching success and
survival of ducklings (1.4% and 0.2%, respectively) compared to diets containing either mercury
(11.3% and 1.1%, respectively) or selenium (24.0% and 2.8%, respectively) alone. The percent
hatchability and survival of ducklings in the 10 mg/kg selenium only diet was low (24% and
2.8%), respectively), but was not significantly different than the control (44.2% and 7.6%,
respectively). Similar to Heinz and Hoffman (1996), the low control percent hatchability did not
meet the test validity for mallards (U.S. EPA 2012) as the percent hatch of fertile eggs in the
control was 44.2%, so these data were not used in the derivation of the bird egg criterion
element. However, the hatchability data do provide qualitative support of the wildlife criterion
(see Part 4.3).
Stanley et al. (1994) examined the independent and interactive effects of dietary selenium
and arsenic on adult mallard breeding pairs at the Patuxent Environmental Science Center,
Laurel, Maryland. Birds received a commercial diet spiked with one of eight dietary treatments.
One of two dietary concentrations of selenium, a control diet and a 10 mg Se/kg diet (as
selenomethionine) were crossed with four arsenic dietary concentrations: control, 25, 100, and
400 mg As/kg, respectively in a 4 x 2 factorial design. Measured selenium concentrations were
0.35 mg Se/kg dw in the control diet and 6.5 mg Se/kg dw in the selenium amended diet. Birds
were fed treated diets for four weeks before pairing, and diets were maintained throughout the
study (115-124 days). The eighth egg from every clutch was measured for selenium and arsenic
concentrations. Eggs were incubated by hens, hatchlings were placed on the same diet as their
56
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parents. Adult and hatchling weights and survival were measured. At the end of the study,
selenium and arsenic was measured in adult and hatchling tissues. No effects on adult weight or
survival were observed when breeding pairs were fed selenium treated diets. Alternatively,
decreased hatching success was observed in the 10 mg/kg selenium treatment group (8.5%)
compared to the control group (91.4%). The occurrence of embryo deformities and duckling
mortality was high in the selenium only treatment group (57.5% and 90%, respectively)
compared to controls (0% and 17.5%, respectively). The independent effects of arsenic were less
pronounced than those of selenium. Hatching success decreased from 91.4% to 74.5%, duckling
mortality increased from 17.5% to 56.7%, and embryo deformities were similar (0% and 2.9%)
between the control and the 400 mg As/kg treatment level. The co-occurrence of arsenic
mitigated the effects of selenium on hatchling success at 400 mg As/kg treatment level (59.7%),
but effects on embryo deformities and duckling mortality were minor (0% and 63.8%
respectively). This study was not included in the combined mallard dataset since the high control
hatchability observed in this study was determined to be statistically different from the other
control groups in the meta-analysis (91.4% compared to 57-64.4%) in the remaining studies).
Thus, the hatchability data from this study provide qualitative support of the wildlife criterion.
Pelecaniformes (Pelicans, Herons, Ibises, and Allies)
Smith et al. (1988) exposed ten breeding pairs of black-crowned night-herons (Nycticorax
nycticorax) to seleno-DL-methionine at dietary concentrations of 0 (control), 10, and 30 mg
Se/kg ww (9% moisture in diet) each over a period of ninety-two days. Average selenium
concentrations measured in eggs were 0.56, 3.3 and 9.2 mg Se/kg fresh wet weight (fww for the
control, 10 and 30 mg/kg ww dietary treatments, respectively). All groups lost weight during the
test, but male and female herons fed the 30 mg Se/kg diet lost more weight than herons fed the
10 mg Se/kg or control diets. The authors attribute this to a possible aversion to the selenium-
treated diets or perhaps illness caused by the selenium treatment. None of the herons died or
showed signs of selenium toxicosis. Hatching success of fertile eggs laid by the 10 mg Se/kg diet
group (43.9%>) did not differ significantly from controls (32.2%). Nor did they show soft tissue,
external, or skeletal deformities, although three day-old hatchlings in the 10 mg Se/kg ww
dietary treatment group had statistically significantly (P<0.05) shorter femur (15.1 mm) and
radius-ulna lengths (10.6 mm) compared to controls (15.7 and 11.3 mm, respectively).
57
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This test was determined to be of sufficient data quality. However, the study authors, who
are experienced with mallard studies described in this document, observed none of the mallard
teratogenic effects that had occurred at the equivalent 10 mg Se/kg ww diet, such as
hydrocephaly, bill and eye defects, and malformations of the legs, feet, and toes. Based on the
absence of such effects, and the absence of a reduction in hatching success, the study authors
conclude that black-crowned night-herons are less sensitive to selenium toxicity than mallards
(Smith et al. 1988). Egg concentrations of the 10 mg Se/kg ww diet group (yielding no effects)
averaged 3.3 mg Se/kg fresh wet weight (n = 5; range 2.7-3.6 mg Se/kg fw). Given the absence
of effects, a threshold cannot be ascertained, but assuming 82.4% moisture content (Sotherland
and Rahn 1987) the dry-weightNOEC would be 18.75 mg Se/kg dw egg. Therefore, this study
was not used quantitatively to derive the selenium criterion for aquatic-dependent wildlife and
was instead used to demonstrate the protectiveness of the criterion at 11.2 mg Se/kg dw based on
the most sensitive endpoint, hatchability, in the most sensitive species, mallard.
Strigiformes (Owls)
Wiemeyer and Hoffman (1996) administered selenium in the form of seleno-DL-
methionine to the diets of adult Eastern screech owls through the breeding season at the Patuxent
Environmental Science Center, Laurel, Maryland. Adults were divided into three groups of
breeding pairs and received either a control (<0.21-0.34 mg Se/kg dw), a low (average 8.81 mg
Se/kg dw), or a high (average 30.0 mg Se/kg dw) selenium diet. Adults were monitored for
changes in weight and survival. Hatchability, growth, and liver enzyme levels were measured.
Adult weights at the end of the study were statistically significantly lower in the high dietary
treatment than the control and low dietary treatment. Egg selenium concentrations in control,
low, and high dietary treatments averaged 0.26 mg Se/kg ww egg, 2.57 mg Se/kg ww egg, and
7.44 mg Se/kg ww egg, respectively. No nestlings survived to five days in the high selenium
treatment; however, nestling survival and average body mass were similar between the control
(2.4 five-day old nestlings per pair and 47.3 g, respectively) and low selenium treatment (3.3
five-day old nestlings per pair and 46.2 g, respectively). For the conventional endpoints of
nestling survival and adult weight, the NOEC was 8.81 mg Se/kg dw diet or 2.57 mg Se/kg ww
egg, and the LOEC was 30.0 mg Se/kg dw diet or 7.44 mg Se/kg ww egg and the MATC was
16.26 mg Se/kg dw in diet or 4.37 mg Se/kg ww. The egg concentrations were further converted
58
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to dry weights assuming a moisture content of 82.2% (Sotherland and Rahn 1987) to make them
comparable with other egg toxicity values reported in the literature and to the bird egg criterion
for selenium. The converted reported egg NOEC was 14.44 mg Se/kg dw, LOEC was 41.80 mg
Se/kg dw, and MATC 24.57 mg Se/kg dw. Therefore, this study was not used quantitatively to
derive the selenium criterion for aquatic-dependent wildlife and was instead used to demonstrate
the protectiveness of the criterion at 11.2 mg Se/kg dw.
Charadriiformes (Plovers, Sandpipers, and Allies)
Hoffman et al. (2002) collected American avocet and black-necked stilt eggs from three
sites with varying levels of selenium and hatched them in the laboratory. Fifteen, twenty-six, and
seventeen avocet eggs were collected from Tulare Lake Drainage District-north Kings County
(TLDD-N, water 2.5 ng/L Se), TLDD-south Kern and Kings Counties (TLDD-S, water 8.6 ng/L
Se) and Westfarmers Kern County (WF, water 190 ng/L Se), respectively. Sixteen, twenty-two
and seventeen stilt eggs were collected from these same respective locations. Geometric mean
egg selenium concentrations in dry weight for avocets were 3.3 mg Se/kg (TLDD-N), 6.7 mg
Se/kg (TLDD-S) and 31.4 mg Se/kg (WF). Geometric mean egg selenium concentrations (dw)
for the stilt eggs were 2.3 mg Se/kg (TLDD-N), 8.4 mg Se/kg (TLDD-S), and 20.5 mg Se/kg
(WF). No meaningful effects were observed in the stilts, which had an overall lower selenium
exposure compared to the avocets. There were no significant reductions in hatching success or
malformations in the avocets, which had comparatively higher exposures (31.4 mg Se/kg dw egg
at WF). There was, however, a small (7%) but significant reduction in chick weight (without
yolk sac) for avocets at the high exposure relative to the reference. The NOEC and LOEC for
this avocet chick weight endpoint were 6.7 mg Se/kg dw egg and 31.4 mg Se/kg dw egg,
respectively with an MATC of 14.5 mg Se/kg dw. This test was considered for qualitative use to
support the protectiveness of the bird egg criterion of 11.2 mg Se/kg dw because of the lack of
effects in hatching success and malformations, the relatively small (7%) difference in yolk sac-
free chick weights, and the large difference in concentrations between the moderately high (6.7
mg/kg dw in eggs) and high exposure sites (31.4 mg/kg dw in eggs).
Harding et al. (2005) investigated the effects of selenium on spotted sandpipers (Actitis
macularia) in areas of elevated selenium stream concentrations and in reference areas in the Elk
River watershed of British Columbia. The average spotted sandpiper egg selenium concentration
59
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was 7.3 mg Se/kg dw in the exposed areas compared to 3.8 mg Se/kg dw in the reference areas.
Fledglings per nest was 3.0 (standard error = 0.2, n = 27) in the exposed areas and 3.5 (standard
error = 0.13, n = 27) in the reference areas. The author-reported egg toxicity value for this study
was > NOEC of 7.3 mg Se/kg dw because the differences in the responses (egg failure,
hatchability, and nestling survival) between exposed and reference areas were not significantly
different. Further, the authors note that despite the slightly reduced hatchability in sandpipers,
overall productivity was higher than regional averages. In addition, no teratogenic effects were
detected in any embryos or juveniles (nestlings) observed. The author-reported NOEC of > 7.3
mg Se/kg dw was used qualitatively to support the protectiveness of the bird egg criterion of 11.2
mg Se/kg dw as spotted sandpipers would likely be protected by the bird egg criterion given the
lack of effects on any measured endpoints at the 7.3 mg Se/kg dw. A decision framework for
non-definitive values was applied that is consistent with past practice (U.S.EPA 2013), The
decision framework was not to use "greater than" values for concentrations of low magnitude or
"less than" values for concentrations of high magnitude because they do not provide meaningful
toxicity information. Additionally, considering the life history characteristics of spotted
sandpipers, which inhabit areas near or along the shoreline of freshwater and consume small
invertebrates (e.g., emergent insects, snails and small crustaceans), they are unlikely to be
exposed to high selenium concentrations.
Black necked stilts {Himantopus mexicanus) are one of the few species with sufficient
selenium exposure data from which to calculate an ECio that can be compared to mallards.
Adams et al. (2003) analyzed field data relating nest inviability in black-necked stilts to selenium
exposure originally presented in Skorupa (1998b). A nest was considered inviable if at least one
egg from a nest was inviable, making nest-wise, or clutch-wise, inviability a more sensitive
endpoint than egg inviability. Skorupa (1998a) applied a weighted average to stilt nests with egg
concentrations ranging from 4-9 mg/kg dw and concluded that the upper bound of safe exposure
for stilt eggs was around 6 mg/kg dw. Using a logistic model, Adams et al. (2003) calculated an
ECio of 16.0 mg/kg dw egg for stilt nest inviability across the full range (approximately 2-75
mg/kg dw) of field egg concentrations presented in Skorupa (1998b). In addition, Adams et al.
(2003) used an empirically calculated equation reported in Skorupa (1998b) to convert the
probability of an inviable clutch to the probability of an inviable egg, so that the stilt field data
would be more comparable to the mallard laboratory data. Adams et al. then grouped inviable
60
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egg data across the full range of selenium concentrations using a variety of binning schemes, and
calculated egg-inviability ECios using "hockey stick" regression ranging between 20.9-31.0
mg/kg dw egg depending on the binning scheme. Based on these results, Adams et al. (2003)
concluded that black necked stilts were less sensitive than mallards when similar endpoints were
compared. Therefore, this study was used qualitatively to demonstrate the protectiveness of the
bird egg criterion at 11.2 mg Se/kg dw.
Passeriformes (Perching Birds)
Weech et al. (2012) examined selenium concentrations in invertebrates and bird eggs of
several species, including tree swallows, in an environment receiving effluent from the Key Lake
uranium mill in northern Saskatchewan, and in nearby reference areas. Hatching success and
nestling health of tree swallows (Tachycineta bicolor) were also examined. Measured tree
swallow egg selenium concentrations had a maximum of 13.3 mg Se/kg dw. The authors found
no significant relationships between tree swallow egg selenium concentrations and hatchability
or clutch size. There was also no difference in the growth of tree swallow nestlings among study
areas. The study therefore does not provide a quantifiable threshold for effects.
However, the NOEC was > 13.3 mg Se/kg dw. This study was considered for qualitative use
since it was a field study with other chemicals potentially present. In particular, the study site
was downstream of a uranium mill and the study authors note that several metals are present at
the site in varying concentrations. However, this study provides insight into the relative
sensitivity of tree swallows exposed to selenium and indicates that the bird egg criterion of 11.2
mg Se/kg dw based on mallards would be protective of this species.
Walls et al. (2015) studied tree swallow reproduction in Watts Bar Reservoir, Tennessee,
in 2009-2010 following the spill of coal fly ash from the Kingston Fossil Plant in 2008. Tree
swallows were exposed to ash-related contaminants via their diet of emergent aquatic insects,
whose larval forms can accumulate constituents from submerged river sediments. Reproduction
of 471 tree swallow nests was assessed over a two-year period. Egg concentrations of mercury
and selenium in the impacted sites were somewhat elevated compared to reference sites. Average
selenium concentrations measured in eggs ranged from 3.15-4.75 mg Se/kg dw egg among six
impacted sites across two years and 2.79-3.04 mg Se/kg dw across the two years at the reference
site. Hatching success at ash-impacted sites (average of 87.4%) was statistically significantly
61
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lower than reference sites (98.5%), but female fledglings produced per nesting female (2.10 and
2.22 for ash-impacted and reference sites, respectively) were not significantly different. The
study authors indicated that this was likely due to larger clutch sizes in the impacted colonies that
was independent of selenium exposure. Even for hatching success, the authors indicate that no
combination of twenty-six potential contaminants measured (including selenium) in the eggs was
predictive in a multiple regression analysis. Therefore, the study does not provide a basis for
establishing an egg concentration threshold for effects. The author-reported NOEC was > 4.75
mg Se/kg dw. This study was considered for qualitative use given that it was a field study with
known mixtures and given the decision framework for non-definitive values that was applied to
be consistent with past practice (U.S.EPA 2013). The decision framework was not to use
"greater than" values for concentrations of low magnitude because they do not provide
meaningful toxicity information. In particular, the study site was downstream of a coal fly ash
spill that occurred in 2008, and the study authors note that several metals are present at the site in
varying concentrations. This study provides little insight into the relative sensitivity of tree
swallows exposed to selenium. However, when the life history characteristics of tree swallow are
considered, since they prefer to inhabit areas near water, but also nest in areas such as fields with
an abundance of small insects, the exposure of selenium to tree swallows is not expected to be as
high as waterfowl, such as mallard, which are the most sensitive species with selenium toxicity
data and are protected by the selenium aquatic-dependent wildlife criterion.
Harding (2008) evaluated the effects of selenium on the reproductive success in red-
winged blackbirds (Agelaiusphoeniceus) at a coal mining site in southeastern British Columbia,
Canada. Nests were monitored at reference sites and sites with elevated selenium for
productivity, hatching success, egg failure, egg size and health, mortality, glutathione
peroxidase, and malformations. Mean egg selenium across sites ranged from 2.96 to 21.7 mg
Se/kg dw with concentrations in individual eggs as high as 40 mg Se/kg dw. The only effect
observed to be related to selenium was hatchability; a quadratic model reported by the study
authors found a significant relationship between hatchability and egg selenium (P < 0.001, n =
116). The study authors indicated adverse effects on hatchability at approximately 22 mg Se/kg
dw egg. This author-reported value was considered a NOEC by the EPA in the development of
this selenium aquatic-dependent wildlife criterion. This study was considered for qualitative use
given that it was a field study with potential mixtures. In particular, the study site was
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downstream of a coal mining site. Additionally, the study use classification was influenced by
the amount of scatter in the hatchability data, which made the independent calculation of an ECio
value problematic. However, this study provides insight into the relative sensitivity of red-
winged blackbirds exposed to selenium and indicates that the bird egg criterion of 11.2 mg Se/kg
dw based on mallards would be protective of this species.
Ratti et al. (2006) collected reproductive data on 298 nests (from 152 reference and 146
mining sites) of American robin (Turdus migratorius) and 325 nests (from 166 reference and 159
mining sites) of red-winged blackbird (Agelaiusphoeniceus) in Idaho. Twelve reproductive
endpoints were measured, including nest success, clutch size, hatching success, fledging success,
egg weight, and neonate weight. Average egg selenium concentrations were somewhat higher at
the mining sites (4.48 mg Se/kg dw and 7.18 mg Se/kg dw in robin and blackbird, respectively)
compared to the reference sites (3.17 mg Se/kg dw and 2.73 mg Se/kg dw in robin and blackbird,
respectively). However, they did not often exceed concentrations that might have been expected
to cause effects (none of the robin eggs exceeded 10 mg Se/kg dw; 13% of blackbird eggs
exceeded 10 mg Se/kg dw). The authors did not observe any reductions in reproductive success.
With no effects observed, the species NOECs are deemed greater than the mining site reported
average concentrations: >4.48 mg Se/kg dw egg for American robin and >7.18 mg Se/kg dw egg
for red-winged blackbird. This study was considered for qualitative use since it was a field study
with known mixtures. In particular, some study sites were in mining areas. However, this study
provides insight into the relative sensitivity of red-winged blackbirds and American robins
exposed to selenium and indicates that the bird egg criterion of 11.2 mg/kg dw based on mallards
would likely be protective of this species. This is especially the case when the life history
characteristics of blackbirds and robins are considered. Blackbirds prefer to nest in areas near
water, such as wetlands and marshes, but also nest in areas such as meadows with an abundance
of small insects. American robins inhabit woodlands and forested areas. Therefore, the exposure
of red-winged blackbirds and American robins to selenium are not expected to be as high as
waterfowl, such as mallard, that appear to be more sensitive to and are likely to experience
higher exposure to selenium.
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4.6.2 Non-Reproductive Studies Used Qualitatively in the Criterion Derivation
Anseriformes (Ducks, Geese, and Swans)
The effects of dietary selenium concentrations as selenomethionine and sodium selenite
on newly hatched mallard ducklings were examined by Heinz et al. (1988) at the Patuxent
Wildlife Research Center in Laurel, MD. One-day old ducklings (n = 40) were assigned to one of
ten treatments, and fed commercial starter mash containing 0, 10, 20, 40, or 80 mg Se/kg in the
chemical form of either sodium selenite or selenomethionine for six weeks. Mortality, weight,
and food consumption were monitored daily throughout the study. Food consumption decreased
significantly in the 20, 40, and 80 mg/kg sodium selenite treatments by week one, and in the
same selenomethionine treatments by week three. Duckling weights were reduced significantly
in the 40 and 80 mg/kg sodium selenite treatments by week one, and in the same
selenomethionine treatments by week two. Significant mortality was observed in the 80 mg
Se/kg treatments for both selenium forms by week one. Mortality decreased significantly in the
40 mg/kg sodium selenite treatments by week two, and in the same selenomethionine treatments
by week three. After six weeks, mortality was 97.5% in the 80 mg/kg sodium selenite treatment
and 100% in the 80 mg/kg selenomethionine treatment. Six-week mortality was 25% in the 40
mg/kg sodium selenite treatment and 12.5% in the 40 mg/kg selenomethionine treatment.
Selenium concentrations in livers among surviving ducklings reached an asymptote of 10 mg/kg
among the sodium selenite treatments, but continued to increasingly bioaccumulate with
concentration levels among the selenomethionine treatments. The dietary LOEC of 40 mg Se/kg
observed for both growth and mortality endpoints in this study was higher than the range of
dietary LOEC values (7 to 16 mg Se/kg) determined for egg hatchability (Heinz et al. 1989;
Stanley et al. 1994, 1996). This finding supports the use of egg hatchability in maternal transfer
studies as a sensitive toxicity endpoint that will be protective of birds.
Hoffman et al. (1992) examined the independent and interactive effects of dietary
selenium and protein levels following a 3 x 3 factorial design, where three levels of dietary
selenium as selenomethionine (control, 15 mg Se/kg, and 60 mg Se/kg) were crossed with three
levels of dietary protein (11% - low, 22% - adequate, and 44% - high), and fed to one-day old
mallard ducklings for 28 days. A separate 2x3 factorial design was conducted using the same
three levels of dietary selenium crossed with the control and low protein diets described above,
where all treatments received supplemental dietary methionine (0.42% in the control diet and
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0.21% in the low protein diet). The study was conducted at the Patuxent Environmental Science
Center, Laurel, Maryland. Reduced 28-day weights were observed in the 15 mg Se/kg high
protein treatment, and in the 60 mg Se/kg control protein treatment. No ducklings receiving 60
mg Se/kg and a low protein diet survived to 28 days. Reduced 28-day tarsal lengths and survival
were observed in both the 60 mg Se/kg low protein and high protein treatments. There were no
statistically significant independent effects of supplemental methionine, although for the 22%
protein diet, survival in the 60 mg Se/kg treatment with the methionine supplement was slightly
higher than the 60 mg Se/kg treatment with no methionine supplement. The dietary NOEC and
LOECs of the standard and low protein treatments of this study were 15 and 60 mg Se/kg dw and
the NOEC of the high protein treatment group was <15 mg Se/kg dw since effects were
observed in the lowest selenium treatment group compared to controls. These toxicity values
were higher than the range of dietary LOEC values (7 to 16 mg Se/kg) determined for egg
hatchability (Heinz et al. 1989; Stanley et al. 1994; Stanley et al. 1996).
Heinz (1993) acclimated ten adult male mallards to either zero (control) or 15 mg Se/kg
as selenomethionine in a nearly dry diet (10% moisture content) for twenty-one weeks. There
were no effects at either dose. After this acclimation period, all birds received the control diet for
an additional 12 weeks. After this period of no exposure, the birds received either zero or 100
mg/kg selenomethionine for 5 weeks in their diet. The acclimation period was found not to
influence mortality (14-15%) or weight reduction (39-41%) during the 5-week 100 mg Se/kg
exposure. From the acclimation period results, it can be concluded that the NOEC is greater than
15 mg Se/kg in diet. As with the previously summarized toxicity studies, this dietary NOEC was
higher than those observed for the reproductive studies of mallard with dietary LOEC values
ranging between 7 to 16 mg Se/kg dw (Heinz et al. 1989; Heinz et al. 1987; Stanley et al. 1996).
Therefore, the selenium criterion for aquatic-dependent wildlife based on the most sensitive
endpoint of hatchability is expected to be protective of the growth effects observed in this study
on adult male mallards.
Heinz and Fitzgerald (1993b) exposed ten adult male mallards to dietary selenium
concentrations of 10, 20, 40, and 80 mg Se/kg ww in a commercial diet, corresponding to 11.3,
22.6, 45.2, and 90.4 mg Se/kg dw (in addition to the control), for sixteen weeks over the winter.
Mortality was monitored for an additional sixteen weeks after the exposure ended. No mortality
was observed at 11.3 mg Se/kg dw diet, 25% was observed at 22.6 mg Se/kg dw diet, and 95-
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100% was observed at 45.2-90.4 mg Se/kg dw diet. The dietary dry weight NOEC (0%
mortality) is 11.3 mg Se/kg dw and the LOEC (25% mortality) is 22.6 mg Se/kg dw. The data
are too sparse to confidently estimate an ECio, but they do suggest a steep concentration-
response slope, with a dietary ECio of approximately 19 mg Se/kg dw. These results indicate that
reduction in overwintering survival of adult mallards begins at dietary concentrations higher than
those yielding reductions in mallard egg hatchability, with dietary LOEC values ranging from 7
to 16 mg Se/kg dw. Therefore, the selenium criterion for aquatic-dependent wildlife based on the
most sensitive endpoint of hatchability is expected to be protective of the growth effects
observed in this study on adult male mallards.
Albers et al. (1996) fed one-year old male mallards a mash diet supplemented with 0, 10,
20, 40, 80 mg Se/kg ww as seleno-DL-methionine. Each treatment consisted of twenty-one
ducks that were fed the selenium-spiked diets for sixteen weeks in outdoor pens. All the ducks
died in the highest dietary treatment (80 mg Se/kg ww), with no significant mortality observed in
any other treatment. The most sensitive effect observed in the test was the number of molts
completed by the end of the sixteen- week treatment period. The number of molts over the
sixteen-week period in the control, 10, 20, 40, and 80 mg Se/kg ww dietary treatments were 21,
17, 19, 5, and 0, respectively. The 40 and 80 mg Se/kg ww treatments were significantly reduced
relative to the control. The NOEC, LOEC and MATC for this test were determined as 20, 40 and
28.3 mg Se/kg ww dietary selenium, respectively, based on the number of molts endpoint. These
dietary concentrations of selenium are more than double those in which egg hatchability effects
were observed in mallards. Therefore, the selenium criterion for aquatic-dependent wildlife
based on the most sensitive endpoint of hatchability is expected to be protective of the growth
effects observed in this study on adult male mallards.
Groups of twelve flightling male mallards were exposed to 0, 10, 25, and 60 mg Se/kg
ww (25%) moisture) dietary selenium as seleno-L-methionine by O'Toole and Raisbeck (1997).
Birds ate little of the 60 mg Se/kg ww diet and became emaciated. Birds on the 25 mg Se/kg ww
diet ate approximately 25% less than birds on the control and 10 mg Se/kg ww diet, but body-
weight reductions were statistically significant only intermittently, mostly during the first half of
the test. Alopecia (baldness) was observed at 25 mg Se/kg ww but not in the control, 10 mg
Se/kg ww, or 60 mg Se/kg ww groups. The dietary NOEC is 10 mg Se/kg ww or 13.3 mg Se/kg
dw, and the dietary LOEC is 25 mg Se/kg ww or 33.3 mg Se/kg dw for the food consumption
66
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endpoint. However, reduction of risk by avoidance of selenium contaminated food is not thought
to occur in real-world situations (U.S. EPA 2016a). If this study's dosing is thought to have
produced an unpalatable diet, then it might not be usable for estimating effect thresholds.
However, this dietary LOEC was higher than those observed for the reproductive studies of
mallard with dietary LOEC values ranging between 7 to 16 mg Se/kg dw (Heinz et al. 1989;
Heinz et al. 1987; Stanley et al. 1996). Therefore, the selenium criterion for aquatic-dependent
wildlife based on the most sensitive endpoint of hatchability is expected to be protective of the
effects observed in this study on adult male mallards.
DeVink et al. (2008) fed breeding pairs of two-year old lesser scaup (Aythya affinis)
environmentally relevant doses (at nominal concentrations of <1, 7.5, and 15 mg Se/kg dw) of
dietary selenium for thirty days. Seleno-L-methionine was added to commercial feed at
measured selenium dry weight concentrations of 0.65 mg Se/kg dw (control), 7.7 mg Se/kg dw,
and 14.9 mg Se/kg dw. There were no effects from selenium on adult survival or the number of
hens laying eggs. The study had a secondary focus of measuring the decrease of selenium in eggs
after the exposure period ended. Egg selenium concentrations decreased from approximately 33
mg Se/kg dw in the high dietary treatment (on the final day of the 30-day exposure) to
approximately 5 mg Se/kg dw in eggs collected 20 days after the selenium supplemented diet
ended. A similar rapid decrease in egg selenium occurred in the 7.7 mg Se/kg diet. Eggs
collected at the end of the 30-day exposure contained approximately 28 mg Se/kg dw; eggs
collected 20 days after the selenium treatment stopped contained approximately 3 mg Se/kg dw.
No selenium effect levels for chronic effects analysis were determined for this study. The
unbounded dietary NOEC of > 14.9 mg Se/kg dw was higher than the dietary LOECs of 7 to 16
mg Se/kg dw from the reproductive studies in which hatchability was the most sensitive endpoint
(Heinz et al. 1989; Heinz et al. 1987; Stanley et al. 1996). Therefore, the selenium criterion for
aquatic-dependent wildlife based on the most sensitive endpoint of hatchability is expected to be
protective of the effects observed in this study on adult male mallards.
Brady et al. (2013) exposed lesser scaup (Aythya affinis) to background/control (0.8 mg
Se/kg dw), moderate (8.1 mg Se/kg dw) and high (20.7 mg Se/kg dw) levels of dietary selenium
as seleno-L-methionine. Fifty-four wild-strain, captive ducks (twenty-eight females and twenty-
six males) were fed the dietary treatments in pens for twenty-three weeks. The ducks in the high
dietary treatment had significantly lower lipids after ten weeks; however, this difference was not
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observed after twenty-three weeks of exposure. After the twenty-three week exposure, there were
no survival effects, selenium-related oxidative stress, or cell-mediated immunity, although
immuno-stimulatory effects on antibody production were observed. No selenium effect levels for
chronic effects analysis were determined for this study. Therefore, the dietary NOEC for this
study was determined to be > 20.7 mg Se/kg dw. This NOEC was higher than the dietary LOECs
(ranging from 7 to 16 mg Se/kg dw) from reproductive mallard studies that were used to derive
the selenium criterion for aquatic-dependent wildlife.
Falconiformes (Falcons and Caracaras)
Yamamoto and Santolo (2000) exposed groups of American kestrels to measured dietary
selenium concentrations of 0.63, 6.3, and 12 mg Se/kg dw for a period of seventy-seven days.
The control group consisted of ten male-female pairs. The treatment groups consisted of fifteen
male-female pairs. Observations of the health of the male birds began at the end of exposure and
continued for 197 days (after the 77-day exposure). The authors excluded the female birds from
the analysis because their weights were too variable. The authors did not report body weights at
the beginning of exposure. If it could be assumed that the groups began the exposure with equal
weights, then relative to the control slight average reductions in total body weight were observed
at the end of the seventy-seven-day exposure period (that is, the beginning of the observation
period): 2.9% reduction at 6.3 mg Se/kg dw and 6.6% reduction at 12 mg Se/kg dw. By the end
of the 197-day observation period, differences were less; average weights in the 6.3 mg Se/kg dw
group were 2.2% greater than controls, and in the 12 mg Se/kg dw group were 3.9% less than
controls. Within-group variability yielded considerable overlap between groups. Most of the
body weight differences were in fat rather than lean tissue (measured non-invasively by total
body electrical conductivity). Overall, the effect of selenium on total body weight was less than
10%) and does not provide a basis for estimation of a threshold. Therefore, it was determined that
the NOEC was 6.3 mg Se/kg dw and the LOEC was 12 mg Se/kg dw for this study. The dietary
LOEC from this study was higher than some of the dietary LOECs (ranging from 7 to 16 mg
Se/kg dw) and was in line with the genus mean chronic value of 9.125 mg Se/kg dw from
reproductive mallard studies that were used to derive the selenium criterion for aquatic-
dependent wildlife. Therefore, the selenium criterion for aquatic-dependent wildlife based on the
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most sensitive endpoint of hatchability is expected to be protective of the effects observed in this
study on adult male mallards.
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Part 5 Method Used to Translate the Bird Egg and Fish Tissue
Criterion Elements into Water Column Elements
5.1 Purpose
This chapter outlines the details of the mechanistic modeling method that was used to
calculate protective default water column values and which also can be used to derive a site-
specific chronic water-column selenium criterion element. This chapter also summarizes the
translation of the fish tissue criterion element to a national water column element in the 2016
selenium aquatic life criterion (U.S. EPA 2016a) and discusses the translation of the bird tissue
criterion element to a water column element that is equivalent to the EPA's national 2016
selenium aquatic life criterion following a similar approach.
The mechanistic modeling method includes deriving and applying an equation to
translate the fish tissue selenium concentration and bird egg selenium concentration to water
column selenium concentrations that are protective of aquatic life and aquatic-dependent
wildlife, respectively. Part 5.5 discusses the translation of the fish (Part 5.5.1) and bird (Part
5.5.2) tissue criterion elements to both lentic and lotic water column elements. The fish tissue-to-
water column translation is a summary of the EPA's 2016 national selenium aquatic life
criterion. Data used in Part 5.5 were obtained from a nationwide search and were used to derive
lentic and lotic chronic water column elements for the national 2016 selenium criterion;
therefore, these data were not considered site-specific. The water elements derived herein are
provided to demonstrate that the 2016 national selenium aquatic life criterion water column
elements are protective of aquatic-dependent wildlife. The approach serves as an example of how
the mechanistic modeling method can be used to translate the tissue-based elements to a site-
specific water value using the performance-based approach.
5.2 Translation from Tissue Concentration to Water Column Concentration Using the
Mechanistic Model
As part of the effort to develop the EPA's 2016 national aquatic life criterion for
selenium (U.S. EPA 2016a), the EPA worked with USGS to derive a translation equation that
utilizes a mechanistic model of bioaccumulation previously published in peer-reviewed scientific
literature (Connolly 1985; Luoma and Fisher 1997; Luoma and Rainbow 2005; Luoma et. al.
1992; Presser 2013; Presser and Luoma 2006, 2010; Schlekat et al. 2002; Thomann 1981; Wang
2001; Wang et. al. 1996). This model quantifies bioaccumulation in animal tissues by assuming
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net bioaccumulation is a balance between assimilation efficiency from diet, ingestion rate, rate of
direct uptake in dissolved forms, loss rate, and growth rate. The equation uses species-specific
food web models, species-specific bioaccumulation parameters (conversion factor (CF) and
trophic transfer factor (TTF)), and a site-specific enrichment factor (EF) to calculate a site-
specific water column concentration element from the fish egg-ovary and bird egg criterion
elements. For more details on the model, please see Section 3.2.1 of the EPA's 2016 aquatic life
criterion (U.S. EPA 2016a). The general model is described by (Equation 5-1).
_ ^bird egg or fish egg
-water jy^composite EF X CF
(Equation 5-1)
Where:
Cwater = Selenium concentration in the water column (|ig/L) (i.e., water column
criterion element)
Cbird egg or fish = Selenium concentration in the eggs of birds (mg/kg) or the eggs or
egg ovaries of fish (mg/kg) (i.e., egg criterion element)
-/yy-L-omposite = Composite trophic transfer factor. The overall TTF, or level of
selenium bioaccumulation from the base of the food chain to the
tissues of the target species. TTFs are defined as concentration in
consumer species divided by concentration in food. Composite TTFs
take into consideration individual TTFs from all levels of the food web.
EF = Enrichment factor. The concentration of selenium in particulate matter
(algae, detritus, sediment) at the base of the food chain divided by the
selenium concentration in water collected at the same time and place
(L/g)
CF = Conversion factor. Whole body to egg-ovary conversion factor
(dimensionless ratio) [Used to convert fish egg-ovary to fish whole
body. Not used for birds, which uses only the bird egg value.]
(Equation 5-1) describes the translation from the concentration of selenium in the eggs of
birds or the eggs and ovaries of fish at the egg or egg/ovary tissue criterion element, respectively,
to the concentration of selenium in the water column that would be protective of these tissue
criterion elements. This translation approach explicitly recognizes the sequential transfer of
selenium between environmental compartments (water, particulate material, invertebrate tissue,
fish tissue, eggs and/or ovary tissue) by incorporating quantitative expressions of selenium
71
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transfer from one compartment to the other. TTFs and CFs are species specific because they are
influenced by the physiology of the animal (Presser and Luoma 2010). EFs are site specific
because of the influence of the local hydrologic environment (Presser and Luoma 2010). Because
this approach uses food web modeling along with species-specific TTF and CF parameters to
quantify most of the transfer between compartments, the only field measurements needed to
relate selenium in egg-ovary of fish or egg of birds to water are measurements from the water
column and particulate material sufficient to calculate EFs.
5.3 Equation Parameters
Empirical or laboratory data related to selenium bioaccumulation in aquatic organisms
are needed to derive the equation parameters EF, TTF, and CF. The EPA obtained these data by
searching published literature using the EPA's public ECOTOX database and other publication
databases. The studies used here are the same as those used in U.S. EPA (2016a) with the
addition of studies that included data on birds. The EPA used this collection of selenium
measurements to calculate EF values and to develop species-specific TTF and CF values in an
unbiased and systematic manner. A more detailed description of how the EPA calculated EFs is
described in the EPA's 2016 Aquatic Life Criterion (U.S. EPA 2016a). How the EPA calculated
TTFs and CFs as they related to aquatic life is described in detail in Appendix B of the EPA's
2016 Aquatic Life Criterion (U.S. EPA 2016a).
5.3.1 Derivation of Trophic Transfer Factor (TTF) Values
The parameter TTFcomposite (composite trophic transfer factor) in (Equation 5-1)
quantitatively represents all dietary pathways of selenium exposure for a particular fish or bird
species within an aquatic system. The parameter is derived from species-specific TTF values
representing the food web characteristics of the aquatic system and the proportion of species
consumed. It is possible to differentiate bioaccumulative potential for different predator species
and food webs by modeling different exposure scenarios. For example, where a fish or bird
species of interest is a trophic level 4 predator that primarily consumes trophic level 3 fish, the
term TTp^omposite can represented as the product of all TTF parameters that includes the
additional trophic level given as:
72
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(Equation 5-2)
where:
JJJ
-------
A) Three trophic levels (simple):
rj-~j.pcompozite j^j-pTLh ^ j^pTLl
Y
TTF713
J-JJTL2
5SS
B) Four trophic levels (simple):
jYpComposHe _ j^pTLA ^ jy^JZ3 x jy-p7Z2
YJfTL4
I TFTU TTF712 w%
Ifffl
C) Three trophic levels (mix within trophic levels):
jYpeompcste = jypTU x [(777^2 x j+ (777^2 x ^
V
TTFTLi
TTF,
w,
W-,
#t> <¦
777v
^7^
D) Three trophic levels (mix across trophic levels):
jjpcomposite = (p-fTU x ^ |+ (7-77^ xJTF712 X Wj
5
ttfTL3
w,
w-
0% ^
JYfTL2
m
E) Four trophic levels (mix across trophic levels):
jjpcompo'j" = ^jjpru x TTFm x 1(, j+ (jtpt
YYFTL4
j-jpTLS
TTfIL:
TTFtu
Figure 5-1. Example aquatic system scenarios and the derivation of the equation parameter
rprppcomposke
Example equations shown here are scenario-specific combinations of (Equation 5-2) and
(Equation 5-3). [Black-necked stilt and American avocet by Tracey Saxby and Catherine Ward.
Osprey by Jane Hawkey. Royal tern by Tracey Saxby. All bird images used with permission
from the Integration and Application Network, University of Maryland Center for Environmental
Science (http;//ian.umces.edu/irnagelibrarv/)1
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The previously derived TTFs for invertebrates and fish that are used and summarized in
this TSD are described in detail in U.S. EPA (2016a). The following paragraphs generally
describe the EPA's approach for TTFs for all taxonomic groups, including the newly derived
TTFs for birds.
The EPA derived TTF values for taxonomic groups of invertebrates, fish, and birds by
either using physiological coefficients found in the literature, or by evaluation of the empirical
relationship between matched pairs of selenium measurements in organisms and the food they
consumed. The latter are empirical measurements of selenium from field studies. For more on
physiological coefficients please see Section 3.2.2.1 in the EPA's 2016 Aquatic Life Criterion
(U.S. EPA 2016a). The EPA searched its collection of available selenium measurements and
identified measurements taken from aquatic organisms or aquatic-dependent birds. For each
measurement from an aquatic organism or aquatic-dependent bird, the EPA searched for
additional measurements from other aquatic organisms or particulate material that were collected
from the same aquatic site and of a type deemed likely to be ingested as a food source or in
conjunction with feeding activity (i.e., lower trophic level). If multiple lower trophic level
measurements were matched to an aquatic organism or bird measurement, the median of the
lower trophic level measurements was calculated. Each pair of measurements, one taken from a
consumer organism and the other representing the diet of the consumer organism, was designated
as a matched pair. For every consumer organism-diet organism pair, TTFs were calculated using
matched measurements from all available sites and studies. The EPA limited particulate data
used to calculate invertebrate TTFs from field data to those aquatic sites with at least two
particulate selenium measurements paired with invertebrate selenium measurements, and only
used sediment measurements if there was at least one measurement from algae or detritus. If
selenium concentrations from more than one category of particulate material (algae, detritus, or
sediment) were available, the EPA used the median selenium concentration of the available
categories as the particulate concentration for that site.
Because selenium is transferred to aquatic animals primarily through aquatic food webs,
the observable concentration of selenium in different environmental compartments may vary
over time. In Section 3.2.2.1 of U.S. EPA (2016a), an analysis was conducted that suggested the
relationship between selenium concentrations in particulate material and invertebrate tissue and
between invertebrate tissue and fish tissue is insensitive to relative collection time within a one-
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year period. These results also suggested that selenium becomes relatively persistent in the
aquatic ecosystem once dissolved selenium transforms to particulate selenium and becomes
bioavailable. Based on these analyses, the EPA concluded that selenium measurements from
samples collected at the same aquatic site within one year of each other are acceptable to use as
matched pairs of measurements from the aquatic sites. For the purposes of matching aquatic-
dependent bird egg measurements to lower trophic level measurements, the EPA used the same
rule established in U.S. EPA (2016a). The EPA concluded that use of this rule would be
appropriate after conducting an analysis to compare TTFs calculated from breeding season data
(defined here as April through July) to TTFs calculated from all available data for the migratory
species. Because many of the bird species analyzed eat invertebrates, and invertebrate sampling
collections are typically conducted outside of the breeding season time frames, many of the
datasets for the breeding season alone did not produce statistically significant regressions. For
those species where enough data were available during the breeding season to produce
statistically significant results, the resulting TTFs were very close to the TTFs calculated from all
data for the same bird species. Note that the EPA chose a relative collection period of one year
based on data taken from many different aquatic sites. Individual aquatic sites may have
selenium loads and/or bioaccumulation characteristics that require different relative collection
time criteria to accurately characterize selenium relationships.
In Section 3.2.2.1 of the EPA's 2016 Selenium Aquatic Life Criterion, the EPA evaluated
the advantages and disadvantages of using either the median ratio of a distribution of matched
pairs of data, or the slopes of linear regression models to derive species-specific TTF values for
field data and ultimately settled on a hybrid approach (U.S. EPA 2016a). Briefly, the approach
includes designating the median of the ratio of matched pairs of selenium measurements as the
TTF value, but only if ordinary least squares (OLS) linear regression of those data resulted in a
significant (P<0.05) fit and positive regression coefficient. Requiring a significant positive OLS
linear regression coefficient confirms the relationship between selenium in organisms and the
food they ingest is adequately represented by the available data. Using the median of the
individual ratios provides an estimate of central tendency for that relationship that is less
sensitive to potential bias from measurements taken from aquatic systems with very high or very
low selenium concentrations. The EPA used this approach for the new bird TTFs derived in this
technical support document (TSD).
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The EPA used the previously calculated TTF values for 13 invertebrate species and 32
fish species, and newly calculated TTF values for eight bird species that live in, or are dependent
on, freshwater aquatic environments in North America. The final TTF values are listed in Table
5-1, Table 5-2, and Table 5-3, respectively. The invertebrate and fish data used to derive these
previously calculated TTF values are provided in Appendix B of U.S. EPA (2016a). The
presence of physiological coefficients for a taxon in Table 5-1 and Table 5-2 indicates that the
TTF values were calculated using those parameters based on laboratory studies. The absence of
physiological coefficients for a taxon indicates that the EPA derived the TTF value using field
data. If a TTF value could be calculated from both physiological coefficients and field data, the
EPA used the TTF value calculated from the substantially larger number of field measurements
to minimize statistical uncertainty.
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Table 5-1. EPA-Derived Trophic Transfer Factor (TTF) Values for Freshwater Aquatic
Invertebrates (U.S. EPA 2016a).
Common name
Scientific name
AE"
IR"
ke"
TTF
Crustaceans
amphipod
Hyalella azteca
-
-
-
1.22
copepod
Copepoda
0.520
0.420
0.155
1.41
crayfish
Astacidae
-
-
-
1.46
water flea
Daphnia magna
0.406
0.210
0.116
0.74
Insects
dragonfly
Anisoptera
-
-
-
1.97
damselfly
Coenagrionidae
-
-
-
2.88
mayfly
Neocloeon triangulifer
-
-
-
2.38
midge
Chironimidae
-
-
-
1.90
water boatman
Corixidae
-
-
-
1.48
Mollusks
Asian clamb
Corbicula fluminea
0.550
0.050
0.006
4.58
zebra mussel
Dreissena polymorpha
0.260
0.400
0.026
4.00
Annelids
blackworm
Lumbriculus variegatus
0.165
0.067
0.009
1.29
Other
zooplankton
-
-
-
1.89
a AE = assimilation efficiency (proportion). IR = ingestion rate (g/g-day). ke = loss rate (/day).
b Not to be confused with Potamocorbula amurensis
Table 5-2. EPA-Derived Trophic Transfer Factor (TTF) Values for Freshwater Fish (U.S.
EPA 2016a).
Common name
Scientific name
AE"
IR"
ke"
TTF
Cypriniformes
blacknose dace
Rhinichthys atratulus
-
-
-
0.71
bluehead sucker
Catostomus discobolus
-
-
-
1.04
longnose sucker
Catostomus catostomus
-
-
-
0.90
white sucker
Catostomus commersonii
-
-
-
1.11
flannelmouth sucker
Catostomus latipinnis
-
-
-
0.98
common carp
Cyprinus carpio
-
-
-
1.20
creek chub
Semotilus atromaculatus
-
-
-
1.06
fathead minnow
Pimephales promelas
-
-
-
1.57
red shiner
Cyprinella liitrensis
-
-
-
1.31
redside shiner
Richardsonius balteatus
-
-
-
1.08
sand shiner
Notropis stramineus
-
-
-
1.56
Cyprinodontiformes
western mosquitofish
Gambusia afftnis
-
-
-
1.21
northern plains killifish
Fundulus kansae
-
-
-
1.27
78
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Common name
Scientific name
AE"
IR"
ke"
TTF
Esociformes
northern pike
Esox Indus
-
-
-
1.78
Gasterosteiformes
brook stickleback
Culaea inconstcms
-
-
-
1.79
Perciformes
black crappie
Pomoxis nigromaculatus
-
-
-
2.67
bluegill
Lepomis macrochirus
-
-
-
1.03
green sunfish
Lepomis cyanellus
-
-
-
1.12
largemouth bass
Micropterus salmoides
-
-
-
1.39
smallmouth bass
Micropterus dolomieu
-
-
-
0.86
striped bass
Morone saxatilis
0.375
0.335
0.085
1.48
walleye
Sander vitreus
-
-
-
1.60
yellow perch
Perca flavescens
-
-
-
1.42
Salmoniformes
brook trout
Salve linus fontinalis
-
-
-
0.88
brown trout
Salmo trutta
-
-
-
1.38
mountain whitefish
Pros opium w illiamsoni
-
-
-
1.38
cutthroat trout
Oncorhynchus clarkii
-
-
-
1.12
rainbow trout
Oncorhynchus mykiss
-
-
-
1.07
Scorpaeniformes
mottled sculpin
Cottus bairdi
-
-
-
1.38
Sculpin
Cottus sp.
-
-
-
1.29
Siluriformes
black bullhead
Ameiurus melas
-
-
-
0.85
channel catfish
Ictalurus punctatus
-
-
-
0.68
a AE = assimilation efficiency (proportion). IR = ingestion rate (g/g-day). ke = loss rate (/day).
Table 5-3. EPA-Derived Trophic Transfer Factor (TTF) Values for Aquatic-Dependent
Birds.
Common name
Scientific name
TTF
Non-Migratory
American coot
Firfica americana
1.89
red winged blackbird
Agelaius phoeniceus
0.86
Migratory
American avocet
Recurvirostra americana
1.44
cinnamon teal
Anas cyanoptera
1.79
eared grebe
Podiceps nigricollis
2.00
gadwall
Anas strepera
1.78
pied billed grebe
Podilymbus podiceps
0.78
yellow headed blackbird
Xanthocephalus xanthocephalus
1.04
79
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For fish species without sufficient data to directly calculate a TTF value, the EPA
estimated the TTF value by sequentially considering higher taxonomic classifications until one or
more taxa for which a calculated TTF value was available matched the taxon being considered. If
the lowest matching taxon was common to more than one species with a TTF value available, the
EPA used the median TTF from the matching species. For example, although data to directly
calculate TTF for northern redbelly dace (Chrosomus eos) were not available, this species is in
the family Cyprinidae, which also includes blacknose dace {Rhinichthys atratirfus), common carp
(Cyprinus carpio), creek chub (Semotilus atromaculatus), fathead minnow {Pimephales
promelas), red shiner (Cyprinella lutrensis), redside shiner (Richardsonius balteatus), and sand
shiner (Notropis stramineus). Because Cyprinidae is the lowest taxonomic classification where
Chrosomus eos matches a species with an available TTF value, the median of the blacknose
dace, common carp, creek chub, fathead minnow, red shiner, redside shiner, and sand shiner TTF
values was used as the TTF value for northern redbelly dace. The data and analyses used to
calculate all TTF values including those estimated by taxonomic classification are provided in
Table B-8 of Appendix B in U.S. EPA (2016a).
Empirical data for egg and diet pairs were not available for eight bird species that were
identified as species of concern for California by U.S. FWS (American dipper, brown pelican,
bald eagle, Ridgway's rail, Light-footed Ridgway's rail, Yuma Ridgway's rail, black rail, and
least tern) (U.S. FWS 2017). Therefore, composite TTFs (see Part 5.4.2) were estimated for these
species of concern from their species-specific dietary compositions and the application of
empirically-derived TTFs from surrogate species with similar diets. When possible, these trophic
level TTFs were applied from closely related surrogate species (in most cases within the same
order). For more details on TTF derivation for each bird species, see Appendix B.
5.3.2 Derivation of Egg-Ovary to Whole Body Conversion Factor (CF) Values for Aquatic Life
The parameter CF (conversion factor) listed in (Equation 5-1) represents the species-
specific partitioning of selenium as measured in the whole body and in egg-ovary tissue of fish.
The EPA derived species-specific CF (Table 5-4) values by applying the same method used to
derive species-specific TTF values, using empirical measurements of selenium concentrations in
different tissues of the same fish. To derive egg-ovary to whole body CF values, the EPA
defined matched pairs of selenium measurements from the whole body and from the eggs or
ovaries measured from the same individual fish or from matched composite samples. Egg-ovary
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concentration was defined as a measurement from either the eggs or the ovaries. If multiple
measurements from both eggs and ovaries of the same individual or matched composite sample
were available, the average value was used. As was the case with TTFs, CFs were calculated
using matched tissue measurements from all available sites and studies for a given species.
The EPA had sufficient egg-ovary and whole body selenium measurements to directly
derive egg-ovary to whole body CF values for 13 species of fish. However, matched pairs of
selenium measurements in eggs and/or ovaries and muscle (M) tissue, and matched pairs of
selenium measurements in muscle and whole body were also available. To derive CF values for
additional fish species, the EPA used either the additional data or a taxonomic classification
approach to estimate CF. The EPA derived 13 CF values directly from matched pairs of egg-
ovary and whole body selenium measurements and an additional seven CF values by multiplying
EO/M and M/WB conversion factors. For more details on CFs for fish see Section 3.2.2.2 and
Appendix B in U.S. EPA (2016a). For the process of translating the bird egg criterion to a water
column concentration, CFs were not necessary, because the only tissue value for birds is for
eggs.
Table 5-4. EPA-Derived Egg-Ovary to Whole Body Conversion Factor (CF) Values (U.S.
EPA 2016a).
Common name
Scientific name
CF
Std. Dev.a
Acipenseriformes
white sturgeon
Acipenser transmontanus
1.69
Cypriniformes
bluehead sucker
Catostomus discobolus
1.82
0.19
flannelmouth sucker
Catostomus latipinnis
1.41
0.20
white sucker
Catostomus commersonii
1.38
0.36
desert pupfish
Cyprinodon macidarius
1.20
0.10
common carp
Cyprinus carpio
1.92
0.49
roundtail chub
Gila robusta
2.07
0.29
fathead minnow
Pimephales promelas
1.40
0.75
creek chub
Semotilus atromacidatus
1.99
1.00
razorback sucker
Xyrauchen texanus
3.11
Esociformes
northern pike
Esox lucius
2.39
Perciformes
bluegill
Lepomis macrochirus
2.13
0.68
green sunfish
Lepomis cyamllus
1.45
0.23
smallmouth bass
Micropterus dolomieu
1.42
0.19
81
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Common name
Scientific name
CF
Std. Dev.a
Salmoniformes
brook trout
Salve linus fontinalis
1.38
Dolly Varden
Salve linus malma
1.61
brown trout
Salmo trutta
1.45
1.81b
rainbow trout
Oncorhynchus mykiss
2.44
cutthroat trout
Oncorhynchus clarkii
1.96
2.03b
mountain whitefish
Prosopium williamsoni
7.39
a Standard deviation for CF values for those species that had egg-ovary and whole body selenium
concentrations.
b The brown trout and cutthroat trout standard deviations for CF values of 1.81 and 2.03 are considerably
higher than the other standard deviations in this table. The brown trout data were taken from two
studies, Formation Environmental (2011) and Osmundson et al. (2007). CF values for three of the four
fish samples from Osmundson et al. were four to six times greater than the median. Also, the
Formation Environmental data consisted of samples collected from natural streams and samples
collected from a fish hatchery. The ('!' values for the fish hatchery samples were four to seven times
lower than the median value. Although collectively, the data set meets the criteria for including the
brown trout CF, the CF values for Osmundson et al. and Formation Environmental hatchery samples
may be anomalously high and low, respectively. Excluding these potentially anomalous data reduces
the brown trout standard deviation to 0.47. The cutthroat trout CF values are from two sources
(Formation Environmental 2012 and Hardy 2005). The reason for the higher variability in the cutthroat
trout CF values is due to the relatively higher ('!' values in the hatchery fish from the Formation study.
The standard deviation for cutthroat trout drops to 0.62 if the hatchery fish are excluded. See Appendix
B of (U.S. EPA 2016a) for a presentation of the data for both species.
5.3.3 Calculation of Site-Specific Enrichment Factor (EF) Values
The most influential step in selenium bioaccumulation occurs at the base of aquatic food
webs (Chapman et al. 2010). The parameter EF characterizes this step by quantifying the
partitioning of selenium between the dissolved and particulate (algae, detritus, and sediment). EF
can vary by at least two orders of magnitude across aquatic systems (Presser and Luoma 2010).
The greatest reduction in uncertainty when translating a fish tissue or bird tissue concentration of
selenium to a water column concentration using (Equation 5-1) is achieved when spatially and
temporally coincident site-specific empirical observations of dissolved and particulate selenium
of sufficient quality and quantity are used to accurately characterize the EF. Thus, when deriving
the 2016 national selenium aquatic life criterion, the EPA only used aquatic sites with sufficient
data to calculate a reasonably reliable EF value.
To calculate the EF of aquatic systems for the 2016 national selenium aquatic life
criterion, the EPA searched its collection of selenium concentration measurements from field
studies (see Section 2.7.8 of U.S. EPA 2016a for a description of data sources and acceptability
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criteria) and identified aquatic sites with measurements from both particulate material and the
water column. The EPA first identified all selenium measurements from algae, detritus, or
sediment, and then searched for corresponding water column measurements from samples
collected at the same aquatic site within one year of the particulate sample. If more than one
water measurement was available for any given particulate measurement, the median was used.
For each of these matched pairs of particulate and water measurements, the EPA calculated the
ratio of particulate concentration to water concentration. If more than one ratio for any given
category of particulate material (algae, detritus, or sediment) was calculated at an aquatic site,
the EPA used the median ratio to characterize the relationship of that category of particulate
material. The geometric mean of the algae, detritus, and sediment ratios was then used as the EF.
Because there were at most only three possible values (one for algae, one for detritus, and one
for sediment), the EPA used the geometric mean to reduce the potential for one of the values to
have excessive influence on the final site EF value.
The availability of selenium measurements from particulate material was limited. In
addition, a majority of particulate measurements were from sediment samples with a
significantly lower correlation to selenium in water (r = 0.34) compared to algae (r = 0.68; Fisher
r-to-z transformation, P<0.001) and detritus (r = 0.94; Fisher r-to-z transformation, P<0.001).
Therefore, to reduce uncertainty in estimating site-specific EF values, the EPA limited its
analysis to those aquatic sites with at least two particulate selenium measurements paired with
corresponding water column measurements, and only used sediment measurements if there was
at least one other measurement from either algae or detritus. Based on these requirements, EF
values were calculated for 96 individual aquatic sites, and these calculated EF values were used
to derive the 2016 national selenium aquatic life criterion.
In using a site-specific PBA approach to calculate site-specific EFs when translating the
fish and bird tissue criterion elements to a water column element, the State will follow the
methods under the PBA approach (Methodfor Translating Selenium Tissue Criterion Elements
into Site-specific Water Column Criterion Elements for California, Version 2 December 2024;
U.S. EPA 2024a).
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5.4 Food Web Models
5.4.1 Aquatic Life
For the 65 aquatic sites where an EF value was calculated and where fish were sampled,
the EPA modeled the food webs for the fish species the studies indicated were present. Some of
those studies provided information about the species and proportions of organisms ingested by
fish, either through direct analysis of stomach contents, or examination of the presence and
prevalence of invertebrate species. For those studies, that site-specific information in the food
web models was used. Most studies, however, did not provide site-specific food web
information. In those cases, the food webs of fish species present were modeled using
information about their typical diet and/or eating habits obtained from the NatureServe database
(http://www.natureserve.org).
After the EPA developed food web models, the EPA identified the appropriate species-
specific TTF values for each model and calculated TTFcomposite. Although individual TTF values
were derived for several different taxa of invertebrates and fish (Table 5-1 and Table 5-2), some
of the food web models included one or more taxa for which no TTF value was available. The
EPA estimated TTF values for these taxa using the same taxonomic approach used to estimate
egg-ovary to whole body, egg-ovary to muscle, and muscle to whole body conversion factors for
taxa without sufficient data. In brief, for taxa with insufficient data to calculate a TTF value, the
EPA sequentially considered higher taxonomic classifications until one or more taxa for which a
TTF value was available matched the taxon being considered. If the lowest matching taxon was
common to more than one species with a TTF value available, the EPA used the median TTF
from the matching species. The EPA parameterized food web models with T'/T's and EFs to
translate the egg-ovary criterion element to a set of water column concentrations in order to
derive the water column concentration element of the selenium criterion. Details of these food
web models are shown in Table B-8 of Appendix B in U.S. EPA (2016a).
5.4.2 Aquatic-Dependent Wildlife
The EPA modeled the food webs for 16 bird species using species-specific dietary
information to calculate composite TTFs. Eight of the bird species' composite TTFs were derived
based on species-specific dietary compositions and an empirically-derived TTF. The remaining 8
bird species' composite TTFs were estimated using their species-specific dietary compositions
and the application of empirically-derived TTFs from surrogate species that had similar diets
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and, when possible, were taxonomically related (within same order). Details regarding bird
jjpcomposite calculations are included in Appendix B.
5.4.2.1 Species-Specific Composite TTFs for Bird Species
Composite TTFs were calculated for eight bird species with empirically derived TTFs in
order to relate selenium concentrations in the bird eggs of those species to selenium in particulate
matter at the base of the food web. Particulate matter is defined here as algae, detritus, and
sediment (U.S. EPA 2016a). Bird dietary compositions were modeled using information from
species-specific descriptions within the Cornell Lab of Ornithology Birds of the World web site:
(https://birdsoftheworld.org/bow/home). The eight bird species with empirically derived TTFs
included two non-migratory (or resident) species: American coot and red-winged blackbird; and
four migratory species: American avocet, cinnamon teal, eared grebe, gadwall, pied-billed grebe,
and yellow headed blackbird.
The EPA first calculated bird TTFs following the general procedure described for the
calculation of TTFs in Part 5.3.1 above. Because six of the eight bird species consumed an
omnivorous diet, the calculation procedure followed for fish was modified as follows. For bird
species whose diet consisted of both plants and animals, information regarding species-specific
dietary descriptions was used to calculate the relative proportions of the bird diet consisting of
plants and animals. For every egg selenium measurement paired with additional selenium
measurements from both aquatic invertebrates and aquatic algae and vascular plants, a weighted
dietary selenium concentration was calculated. As with fish, paired data were required to be
collected at the same site within a one-year period (see Part 5.3.1 for additional details). Also,
following the approach used for fish, all paired invertebrate or primary producer species were
included, and considered as surrogates for dietary species from that trophic level. When more
than one paired potential diet item from the same trophic level was available, the median
selenium concentration was used.
Egg selenium concentrations and selenium concentrations in modeled diet organisms
were natural log transformed and evaluated using linear regression after removing outliers. If the
slope of a set of matched pairs of selenium measurements was both positive and statistically
significant (P <_0.05), then the relationship between selenium in the target bird species and the
food it consumes is considered adequately represented by the available data. Paired data and
regression results, as well as a more detailed description of the procedure used to determine
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outliers, can be found in Appendix B. For each set of paired data meeting the regression criteria,
the ratio of each egg selenium measurement was divided by its corresponding paired dietary
selenium measurement, and the species-specific TTF for that trophic level was calculated as the
median ratio of all pairs of data.
Next, food webs were constructed by estimating the diet of each target bird species from
the species-specific descriptions, and a final species-specific TTFco"'pos'te was calculated using
(Equation 5-2) and (Equation 5-3). The TTFTL2 linking the invertebrates consumed by that bird
species to the base of the food web is calculated by applying TTFs for invertebrate species or
groups of species obtained from U.S. EPA (2016a) (Table 5-1 here) to the corresponding
invertebrate taxa in the modeled bird species' diet. Table 5-5 lists TTFcomposite for the eight bird
species for which TTFs could be calculated. Dietary information and calculations performed to
calculate TTFcomposite for these species are listed in Appendix B.
Table 5-5. EPA-Derived Composite Selenium Trophic Transfer Factors (TTFcomposite) for
Aquatic-Dependent Birds.
Non-Migratory Species
j^ppcomposite
American coot
2.48
red-winged blackbird
1.67
Migratory Species
rprppcomposite
American avocet
2.61
cinnamon teal
3.04
eared grebe
3.15
gadwall
2.24
pied-billed grebe
1.47
yellow-headed blackbird
1.93
5.4.2.2 Threatened and Endangered Species of Concern Composite TTFs
Empirical data for egg and diet pairs were not available for the following species of
concern in California: American dipper, brown pelican, bald eagle, Ridgway's rail, light-footed
Ridgway's rail, Yuma Ridgway's rail, black rail, and least tern. These species were identified as
species of concern by U.S. FWS in the following report: "Species at Risk from Selenium
Exposure in California Inland Surface Waters, Enclosed Bays and Estuaries'" (U.S. FWS 2017).
Species-specific dietary descriptions for these Threatened and Endangered (T&E) species were
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used to model the relative proportions of the bird diet consisting of plants and animals, and then
paired selenium data from an appropriate surrogate species were weighted accordingly to
calculate a species-specific (egg to diet) TTF. Composite TTFs were then calculated for these
species of concern using their species-specific dietary composition and species-specific TTF
derived from a surrogate species. The surrogate species selected was based on similarity in
dietary composition and if possible taxonomic relatedness (within same order). For bird species
that consumed fish, the pied-billed grebe TTF was used as a surrogate, as pied-billed grebe is the
only piscivore with sufficient data to calculate a TTF. Table 5-6 lists TTFcomp"slte values for the
eight T&E species in California, with the surrogate species in parentheses. Specific calculations
used to generate these TTFco"'pos'te values are included in Appendix B.
Table 5-6. Composite Selenium Trophic Transfer Factors (TTFcomposUe) for Aquatic-
Dependent Bird Species of Concern in California.
Surrogate species (from Table 5-3) used for TTFs in parentheses.
California Bird Species of Concern
(surrogate species used)
Scientific name
rprppcomposite
American dipper (average of red-winged
blackbird and yellow-headed blackbird)
Cinclus mexiccimis
2.08
brown pelican (pied-billed grebe)
Peleccmus occidentalis
1.79
bald eagle (pied-billed grebe)
Haliaeetus leucocephalus
1.75
Ridgway's rail (American coota)
Rallus obsoletus
3.19
light-footed Ridgway's rail (American coota)
Rallus obsoletus levipes
1.70
Yuma Ridgway's rail (American coota)
Rallus obsoletus yumanensis
1.33
black rail (American coota)
Laterallus jamaicensis
1.69
least tern (pied-billed grebe)
Sternula antillarum
1.84
a Species-specific TTFs calculated using American coot paired data weighted to account for
species-specific plant vs. animal proportions (See Appendix B for details).
5.5 Deriving National Protective Water Column Concentrations for Lentic and Lotic
Systems
5.5.1 Aquatic Life
To derive the water column element for the 2016 national selenium aquatic life criterion,
the EPA translated the egg-ovary criterion element to a distribution of water column
concentration values for lentic and lotic aquatic systems. The EPA used the EF values calculated
for 96 aquatic sites, available information about the fish species present at those sites, and food
web models of those fish species. Because translation of the egg-ovary criterion element is site-
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and species-specific, several studies identifying more than one species of fish could potentially
provide more than one translated water column concentration (one translated water value for
each species). The EPA considered using all water column values for all species present to
generate distributions of translated water column values from lentic and lotic aquatic sites.
However, the number of reported fish species at aquatic sites with an EF value varied from one
to six fish species. Furthermore, the studies providing data for 31 of the 96 sites with EF values
do not provide information on the species of fish that may have been present at the aquatic site.
Because the number of fish species at an aquatic site was not consistently reported, and because
the number of reported fish species does not necessarily indicate the number of species present at
a site, the EPA calculated one translated egg-ovary criterion element to water column value for
each aquatic site with both an EF value and at least one reported fish species. When more than
one species was reported at a site, the EPA used the lowest translated water value for that site.
Using this methodology, the EPA translated the egg-ovary FCV into water column
concentrations at 26 lentic and 39 lotic aquatic sites. The EPA used these distributions of water
concentration values translated from the egg-ovary criterion element to derive chronic water
column criterion element values for lentic and lotic aquatic systems. Table 5-7 shows the model
parameter values used to translate the egg-ovary criterion element to individual water
concentrations for each site used in the 2016 national selenium aquatic life criterion, and Figure
5-2 shows the distribution of the translated values. For more information on how the EPA
classifies lotic (flowing waters) and lentic (standing waters) waters see Section 3.2.4 Classifying
Categories of Aquatic Systems in U.S. EPA (2016a). The translated water column values for each
individual site in Table 5-7 were used as part of a distribution to derive a protective water
column element value on a national basis for the 2016 national selenium aquatic life criterion.
The resultant concentration of selenium concentration the water column 1.5 |ig/L in lentic
aquatic systems and 3.1 |ig/L in lotic aquatic systems unless or until a site-specific water column
criterion element is derived for a particular waterbody following the methodology does not
exceed described in Methodfor Translating Selenium Tissue Criterion Elements into Site-
specific Water Column Criterion Elements for California, Version 2 December 2024.
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Table 5-7. Data for the 65 Site Minimum Translations of the Fish Egg-Ovary Criterion Concentration Element to a Water
Column Concentration (U.S. EPA 2016a).
Identification
Model Parameters
Translation
Reference
Site
Species
Type
EF'
CP3
0 mP° site-c
r1 d
^ water
(Hg/L)
Birkner 1978
East Allen Reservoir, Medicine Bow WY
Iowa darter
Lentic
2.31
1.45
2.87
1.57
Birkner 1978
Galett Lake, Laramie WY
Iowa darter
Lentic
0.88
1.45
2.87
4.15
Birkner 1978
Larimer Highway 9 Pond, Fort Collins CO
northern plains killifish
Lentic
1.70
1.20
2.44
3.04
Birkner 1978
Meeboer Lake, Laramie WY
northern plains killifish
Lentic
0.58
1.20
2.44
8.96
Birkner 1978
Miller's Lake, Wellington CO
Iowa darter
Lentic
2.37
1.45
2.87
1.53
Birkner 1978
Sweitzer Lake, Delta CO
fathead minnow
Lentic
0.87
1.40
2.78
4.45
Birkner 1978
Twin Buttes Reservoir, Laramie WY
Iowa darter
Lentic
1.21
1.45
2.87
3.01
Bowie etal. 1996
Hyco Reservoir
Bluegill
Lentic
2.35
2.13
2.00
1.51
Butler etal. 1993
Navajo Reservoir, Piedra River Arm, near
La Boca
brown trout
Lentic
1.26
1.45
2.78
2.98
Butler etal. 1997
Large pond south of G Road, southern
Mancos Valley
fathead minnow
Lentic
2.00
1.40
2.78
1.94
Butler etal. 1997
Pond downstream from site MNP2,
southern Mancos Valley
smallmouth bass
Lentic
5.15
1.42
1.93
1.07
Butler etal. 1997
Pond on Woods Canyon at 15 Road
fathead minnow
Lentic
0.90
1.40
2.78
4.29
Grasso et al. 1995
Arapahoe Wetlands Pond
fathead minnow
Lentic
0.86
1.40
2.78
4.49
Lemly 1985
Badin Lake
red shiner
Lentic
12.48
1.95
2.27
0.27
Lemly 1985
Belews Lake
red shiner
Lentic
1.75
1.95
2.27
1.94
Lemly 1985
High Rock Lake
red shiner
Lentic
4.99
1.95
2.27
0.68
Muscatello and Janz
2009
Vulture Lake
northern pike
Lentic
1.01
2.39
4.02
1.56
Orr et al. 2012
Clode Pond 11
cutthroat trout
Lentic
0.71
1.96
2.29
4.70
Orr et al. 2012
Elk Lakes 14
cutthroat trout
Lentic
1.64
1.96
2.29
2.05
Orr et al. 2012
Fording River Oxbow 10
cutthroat trout
Lentic
1.34
1.96
2.29
2.50
Orr et al. 2012
Henretta Lake 27
cutthroat trout
Lentic
0.50
1.96
2.29
6.72
Saiki and Lowe
1987
Kesterson Pond 11
western mosquitofish
Lentic
0.51
1.20
2.37
10.52
Saiki and Lowe
1987
Kesterson Pond 2
western mosquitofish
Lentic
0.32
1.20
2.37
16.83
89
-------
Identification
Model Parameters
Translation
Reference
Site
Species
Type
EF'
CF°
jj^omposite-c
P d
^ water
(Hg/L)
Saiki and Lowe
1987
Kesterson Pond 8
western mosquitofish
Lentic
0.60
1.20
2.37
8.84
Saiki and Lowe
1987
Volta Pond 26
western mosquitofish
Lentic
0.93
1.20
2.37
5.69
Stephens et al. 1988
Marsh 4720
common carp
Lentic
0.10
1.92
1.58
52.02
Butler etal. 1991
Uncompahgre River at Colona
rainbow trout
Lotic
0.63
2.44
2.33
4.21
Butler etal. 1993
Spring Cr. at La Boca
brown trout
Lotic
0.18
1.45
2.78
20.97
Butler etal. 1995
Hartman Draw near mouth, at Cortez
fathead minnow
Lotic
0.15
1.40
2.78
26.04
Butler etal. 1995
McElmo Cr. at Hwy. 160, near Cortez
fathead minnow
Lotic
0.90
1.40
2.78
4.32
Butler etal. 1995
McElmo Cr. downstream from Alkali
Cyn.
fathead minnow
Lotic
0.37
1.40
2.78
10.57
Butler etal. 1995
McElmo Cr. downstream from Yellow
Jacket Cyn.
red shiner
Lotic
0.12
1.95
2.27
28.34
Butler etal. 1995
McElmo Cr. upstream from Yellow Jacket
Cyn.
red shiner
Lotic
0.10
1.95
2.27
35.60
Butler etal. 1995
Navajo Wash near Towaoc
speckled dace
Lotic
0.20
1.95
1.36
29.07
Butler etal. 1995
San Juan River at Four Comers
red shiner
Lotic
0.26
1.95
2.27
12.97
Butler etal. 1995
San Juan River at Mexican Hat Utah
common carp
Lotic
0.29
1.92
1.58
17.24
Butler etal. 1995
Woods Cyn. Near Yellow Jacket
fathead minnow
Lotic
0.40
1.40
2.78
9.60
Butler etal. 1997
Cahone Canyon at Highway 666
green sunfish
Lotic
0.20
1.45
2.29
23.22
Butler etal. 1997
Mud Creek at Highway 32, near Cortez
fathead minnow
Lotic
0.07
1.40
2.78
55.27
Casey 2005
Deerlick Creek
rainbow trout
Lotic
2.24
2.44
2.33
1.18
Casey 2005
Luscar Creek
rainbow trout
Lotic
0.33
2.44
2.33
8.14
Formation
Environmental 2012
Crow Creek - 1A
brown trout
Lotic
0.80
1.45
2.96
4.42
Formation
Environmental 2012
Crow Creek - 3A
brown trout
Lotic
0.81
1.45
2.97
4.37
Formation
Environmental 2012
Crow Creek - CC150
brown trout
Lotic
1.04
1.45
2.91
3.44
Formation
Environmental 2012
Crow Creek - CC350
brown trout
Lotic
1.16
1.45
2.97
3.02
90
-------
Identification
Model Parameters
Translation
Reference
Site
Species
Type
EF'
CP
jj^omposite-c
P d
^ water
(Hg/L)
Formation
Environmental 2012
Crow Creek - CC75
brown trout
Lotic
1.19
1.45
2.87
3.07
Formation
Environmental 2012
Deer Creek
brown trout
Lotic
1.55
1.45
3.00
2.25
Formation
Environmental 2012
Hoopes Spring - HS
brown trout
Lotic
0.24
1.45
3.86
11.06
Formation
Environmental 2012
Hoopes Spring - HS3
brown trout
Lotic
0.54
1.45
2.63
7.40
Formation
Environmental 2012
Sage Creek - LSV2C
brown trout
Lotic
0.45
1.45
3.01
7.76
Formation
Environmental 2012
Sage Creek - LSV4
brown trout
Lotic
0.69
1.45
2.88
5.22
Formation
Environmental 2012
South Fork Tincup Cr.
brown trout
Lotic
1.32
1.45
3.05
2.58
Hamilton and Buhl
2004
Lower East Mill Creek
cutthroat trout
Lotic
1.32
1.96
2.29
2.55
McDonald and
Strosher 1998
Elk R. above Cadorna Cr. (745)
mountain whitefish
Lotic
6.30
7.39
2.97
0.11
McDonald and
Strosher 1998
Fording R. above Swift Cr. (746)
cutthroat trout
Lotic
0.23
1.96
2.29
14.91
Orr et al. 2012
Elk River 1
cutthroat trout
Lotic
0.55
1.96
2.29
6.14
Orr et al. 2012
Elk River 12
cutthroat trout
Lotic
2.67
1.96
2.29
1.26
Orr et al. 2012
Fording River 23
cutthroat trout
Lotic
0.21
1.96
2.29
16.20
Orr et al. 2012
Michel Creek 2
cutthroat trout
Lotic
0.28
1.96
2.29
11.85
Saiki and Lowe
1987
San Luis Drain
western mosquitofish
Lotic
0.36
1.20
2.37
14.81
Saiki and Lowe
1987
Volta Wasteway
western mosquitofish
Lotic
1.03
1.20
2.37
5.17
Saiki et al. 1993
Mud Slough at Gun Club Road
Bluegill
Lotic
1.37
2.13
1.47
3.53
Saiki et al. 1993
Salt Slough at the San Luis National
Wildlife Refuge
Bluegill
Lotic
0.43
2.13
1.47
11.29
Saiki et al. 1993
San Joaquin R. above Hills Ferry Road
Bluegill
Lotic
0.36
2.13
1.47
13.50
91
-------
Idonliriciilion
Model I'iinimelers
Tmnshilion
Reference
Silc
Species
Type
( 7-1'
y*y'y,vnin|)Hsiii- r
( h.iIit'1
(MS/I.)
Saiki et al. 1993
San Joaquin R. at Durham Ferry State
Recreation Area
Bluegill
Lotic
0.75
2.13
1.47
6.46
a - Geometric mean of the median enrichments factors (EF) for a
b - Taxa-specific conversion whole body to egg-ovary conversior
c - Composite trophic transfer factor (77iFcomP°s'tey Product of 777
d - Translated water selenium concentration corresponding to an
1 available food types (algae, detritus, and sediment). EF (L/g) = Cf0od/Cater.
factor (CF; dimensionless ratio).
7 values for all trophic levels.
sgg-ovary criterion element of 15.1 mg Se/kg dw, calculated by (Equation 5-1).
92
-------
Cumulative
proportion
m
*
X
*
X
A *
X
x*
X
*
X
x
1
m- X
.1
xx
X
1* *Lotic
X
i Lentic
* s
'
X
X
X
*
*
X
1 1 1 1 1 1 1 1 1
, ,
10
100
Water (tig I.")
Figure 5-2. Probability distribution of the water column concentrations translated from the
fish egg-ovary criterion element at 26 lentic and 39 lotic aquatic sites (U.S. EPA 2016a).
Dashed and dash-dot lines show the 20th percentiles of the lentic and lotic distributions,
respectively.
In the 2016 national selenium aquatic life criterion, the EPA selected the 20th percentile
from the distribution of translated water column values of each category as the final national
water column criterion element concentrations (3.1 |ig/L for lotic waters and 1.5 |ig/L for lentic
waters) because the 20th percentile is consistent with past practice as it provides a high
probability of protection for most aquatic systems in both lentic and lotic categories. Table 5-8
provides the 20th percentile of the water concentration values translated from the fish egg-ovary
criterion element value. These values were calculated by applying the mechanistic modeling
method on a national scale and are considered appropriate for California.
Table 5-8. Water Column Criterion Element Concentration Values Translated from the
Fish Egg-Ovary Criterion Element in the 2016 National Selenium Aquatic Life Criterion
(U.S. EPA 2016a).
Lentic
Lotic
20th percentile
(final 2016 EPA recommended water column criterion
element protective of aquatic life)
1.5 jig/L
3.1 jig/L
93
-------
As discussed in Section 2.2.2 of U.S. EPA (2016a), selenium bioaccumulation potential
depends on several biogeochemical factors that characterize a particular aquatic system.
Uncertainty in the translation of the egg-ovary criterion element to the water column element can
be reduced by deriving a site-specific water column criterion element that uses site-specific
selenium data and information on food web dynamics from a biological assessment of the
aquatic system. The general considerations are provided in the performance-based approach
(Methodfor Translating Selenium Tissue Criterion Elements into Site-specific Water Column
Criterion Elements for California, Version 2 December 2024) and in Appendix K of U.S. EPA
(2016a).
5.5.2 Aquatic-Dependent Wildlife
To translate the bird tissue criterion elements into a water column concentration that is
comparable to the 2016 national aquatic life criterion and to determine whether the U.S. EPA
(2016a) national water column criterion element (Table 5-8) is also protective of aquatic-
dependent wildlife, the EPA translated the bird egg tissue element to a distribution of water
column concentration values for the same lentic and lotic aquatic systems. To translate the bird
egg tissue element, the EPA utilized information from the same 65 aquatic sites shown in Table
5-7 and in U.S. EPA (2016a) in addition to the food web models of 16 bird species (see Parts
5.4.2.1 and 5.4.2.2) with a variety of diets, from plants and insects to fish. Using a similar
methodology to the one described in Part 5.5.1, the EPA translated the bird egg final criteria
value into water column concentrations at 26 lentic and 39 lotic aquatic sites. At each site, the
EPA used (Equation 5-1) to translate from the bird egg criterion element of 11.2 mg Se/kg dw to
a water column concentration using the EF for that site and the maximum T]"FcomP°slte for the 16
modeled bird species. The EPA chose to translate the bird egg element using the maximum
jjpcomposite 5ecause jt generates the most protective water column concentration that would
sufficiently protect sensitive species in bioaccumulative food webs. This is consistent with the
approach of selecting the most bioaccumulative food web for the fish species analysis in the
2016 Final Aquatic Life Selenium Criterion for Freshwater (U.S. EPA 2016a). Table 5-9 shows
the model parameter values used to translate the bird egg criterion element value to individual
water concentrations using data for each site used in the 2016 national selenium aquatic life
criterion, and Figure 5-3 shows the distribution of the translated water column values. The
translated water column values for each individual site in Table 5-9 were used as part of a
94
-------
distribution to calculate a protective water column element, paralleling the approach used in the
2016 national selenium aquatic life criterion. These values are default values for the State. The
State could also consider following the methodology described in the performance-based
approach to translate the bird tissue criterion element into a protective water column criterion
element value for a specific site under consideration.
95
-------
Table 5-9. Data for the 65 Site Minimum Translations of the Bird Egg Criterion Concentration Element to a Water Column
Concentration.
Sites and enrichment factors (EF) are those used to translate the fish egg-ovary criterion concentration element to water column
concentrations (U.S. EPA 2016a). The TTFco"'pos'te for Ridgway's rail was used for all sites, as it is the largest among the 16 bird
species described in this document, resulting in the most protective water column concentrations.
Identification
Model Parameters
Translation
Reference
Site
Species
Type
EF*
yyycomposite-b
CwaterC
fag/L)
Birkner 1978
East Allen Reservoir, Medicine Bow
WY
Ridgway's rail
Lentic
2.31
3.19
1.52
Birkner 1978
Galett Lake, Laramie WY
Ridgway's rail
Lentic
0.88
3.19
4.01
Birkner 1978
Larimer Highway 9 Pond, Fort Collins
CO
Ridgway's rail
Lentic
1.70
3.19
2.06
Birkner 1978
Meeboer Lake, Laramie WY
Ridgway's rail
Lentic
0.58
3.19
6.08
Birkner 1978
Miller's Lake, Wellington CO
Ridgway's rail
Lentic
2.37
3.19
1.48
Birkner 1978
Sweitzer Lake, Delta CO
Ridgway's rail
Lentic
0.87
3.19
4.02
Birkner 1978
Twin Buttes Reservoir, Laramie WY
Ridgway's rail
Lentic
1.21
3.19
2.91
Bowie et al. 1996
Hyco Reservoir
Ridgway's rail
Lentic
2.35
3.19
1.50
Butler et al. 1993
Navajo Reservoir, Piedra River Arm,
near La Boca
Ridgway's rail
Lentic
1.26
3.19
2.78
Butler et al. 1997
Large pond south of G Road, southern
Mancos Valley
Ridgway's rail
Lentic
2.00
3.19
1.75
Butler et al. 1997
Pond downstream from site MNP2,
southern Mancos Valley
Ridgway's rail
Lentic
5.15
3.19
0.68
Butler et al. 1997
Pond on Woods Canyon at 15 Road
Ridgway's rail
Lentic
0.90
3.19
3.88
Grasso et al. 1995
Arapahoe Wetlands Pond
Ridgway's rail
Lentic
0.86
3.19
4.06
Lemly 1985
Badin Lake
Ridgway's rail
Lentic
12.48
3.19
0.28
Lemly 1985
Belews Lake
Ridgway's rail
Lentic
1.75
3.19
2.01
Lemly 1985
High Rock Lake
Ridgway's rail
Lentic
4.99
3.19
0.70
Muscatello and Janz
2009
Vulture Lake
Ridgway's rail
Lentic
1.01
3.19
3.47
Orr et al. 2012
Clode Pond 11
Ridgway's rail
Lentic
0.71
3.19
4.91
96
-------
Identification
Model Parameters
Translation
Reference
Site
Species
Type
/:/¦'
yyycomposite-b
CwaterC
fag/L)
Orr et al. 2012
Elk Lakes 14
Ridgway's rail
Lentic
1.64
3.19
2.14
Orr et al. 2012
Fording River Oxbow 10
Ridgway's rail
Lentic
1.34
3.19
2.61
Orr et al. 2012
Henretta Lake 27
Ridgway's rail
Lentic
0.50
3.19
7.02
Saiki and Lowe 1987
Kesterson Pond 11
Ridgway's rail
Lentic
0.51
3.19
6.94
Saiki and Lowe 1987
Kesterson Pond 2
Ridgway's rail
Lentic
0.32
3.19
11.11
Saiki and Lowe 1987
Kesterson Pond 8
Ridgway's rail
Lentic
0.60
3.19
5.83
Saiki and Lowe 1987
Volta Pond 26
Ridgway's rail
Lentic
0.93
3.19
3.76
Stephens et al. 1988
Marsh 4720
Ridgway's rail
Lentic
0.10
3.19
36.65
Butler etal. 1991
Uncompahgre River at Colona
Ridgway's rail
Lotic
0.63
3.19
5.57
Butler et al. 1993
Spring Cr. at La Boca
Ridgway's rail
Lotic
0.18
3.19
19.63
Butler et al. 1995
Hartman Draw near mouth, at Cortez
Ridgway's rail
Lotic
0.15
3.19
23.54
Butler et al. 1995
McElmo Cr. at Hwy. 160, near Cortez
Ridgway's rail
Lotic
0.90
3.19
3.90
Butler et al. 1995
McElmo Cr. downstream from Alkali
Cyn.
Ridgway's rail
Lotic
0.37
3.19
9.55
Butler et al. 1995
McElmo Cr. downstream from Yellow
Jacket Cyn.
Ridgway's rail
Lotic
0.12
3.19
29.28
Butler et al. 1995
McElmo Cr. upstream from Yellow
Jacket Cyn.
Ridgway's rail
Lotic
0.10
3.19
36.78
Butler et al. 1995
Navajo Wash near Towaoc
Ridgway's rail
Lotic
0.20
3.19
17.93
Butler et al. 1995
San Juan River at Four Comers
Ridgway's rail
Lotic
0.26
3.19
13.40
Butler et al. 1995
San Juan River at Mexican Hat Utah
Ridgway's rail
Lotic
0.29
3.19
12.15
Butler et al. 1995
Woods Cyn. Near Yellow Jacket
Ridgway's rail
Lotic
0.40
3.19
8.68
Butler et al. 1997
Cahone Canyon at Highway 666
Ridgway's rail
Lotic
0.20
3.19
17.98
Butler et al. 1997
Mud Creek at Highway 32, near Cortez
Ridgway's rail
Lotic
0.07
3.19
49.96
Casey 2005
Deerlick Creek
Ridgway's rail
Lotic
2.24
3.19
1.57
Casey 2005
Luscar Creek
Ridgway's rail
Lotic
0.33
3.19
10.79
Formation
Environmental 2012
Crow Creek - 1A
Ridgway's rail
Lotic
0.80
3.19
4.40
97
-------
Identification
Model Parameters
Translation
Reference
Site
Species
Type
/:/¦'
yyycomposite-b
CwaterC
fag/L)
Formation
Environmental 2012
Crow Creek - 3 A
Ridgway's rail
Lotic
0.81
3.19
4.36
Formation
Environmental 2012
Crow Creek - CC150
Ridgway's rail
Lotic
1.04
3.19
3.37
Formation
Environmental 2012
Crow Creek - CC350
Ridgway's rail
Lotic
1.16
3.19
3.02
Formation
Environmental 2012
Crow Creek - CC75
Ridgway's rail
Lotic
1.19
3.19
2.96
Formation
Environmental 2012
Deer Creek
Ridgway's rail
Lotic
1.55
3.19
2.26
Formation
Environmental 2012
Hoopes Spring - HS
Ridgway's rail
Lotic
0.24
3.19
14.36
Formation
Environmental 2012
Hoopes Spring - HS3
Ridgway's rail
Lotic
0.54
3.19
6.55
Formation
Environmental 2012
Sage Creek - LSV2C
Ridgway's rail
Lotic
0.45
3.19
7.86
Formation
Environmental 2012
Sage Creek - LSV4
Ridgway's rail
Lotic
0.69
3.19
5.06
Formation
Environmental 2012
South Fork Tincup Cr.
Ridgway's rail
Lotic
1.32
3.19
2.65
Hamilton and Buhl
2004
Lower East Mill Creek
Ridgway's rail
Lotic
1.32
3.19
2.67
McDonald and
Strosher 1998
Elk R. above Cadorna Cr. (745)
Ridgway's rail
Lotic
6.30
3.19
0.56
McDonald and
Strosher 1998
Fording R. above Swift Cr. (746)
Ridgway's rail
Lotic
0.23
3.19
15.57
Orr et al. 2012
Elk River 1
Ridgway's rail
Lotic
0.55
3.19
6.41
Orr et al. 2012
Elk River 12
Ridgway's rail
Lotic
2.67
3.19
1.32
Orr et al. 2012
Fording River 23
Ridgway's rail
Lotic
0.21
3.19
16.92
Orr et al. 2012
Michel Creek 2
Ridgway's rail
Lotic
0.28
3.19
12.37
98
-------
Identification
Model Parameters
Translation
Reference
Site
Species
Type
EF*
yyycomposite-b
CwaterC
fag/L)
Saiki and Lowe 1987
San Luis Drain
Ridgway's rail
Lotic
0.36
3.19
9.77
Saiki and Lowe 1987
Volta Wasteway
Ridgway's rail
Lotic
1.03
3.19
3.41
Saiki et al. 1993
Mud Slough at Gun Club Road
Ridgway's rail
Lotic
1.37
3.19
2.57
Saiki et al. 1993
Salt Slough at the San Luis National
Wildlife Refuge
Ridgway's rail
Lotic
0.43
3.19
8.22
Saiki et al. 1993
San Joaquin R. above Hills Ferry Road
Ridgway's rail
Lotic
0.36
3.19
9.83
Saiki et al. 1993
San Joaquin R. at Durham Ferry State
Recreation Area
Ridgway's rail
Lotic
0.75
3.19
4.71
a - Geometric mean o:
?the median enrichment factors (EF) for all available food types (algae, detritus, and sediment). EF (L/g) =
Cfood/Cwater.
b - Composite trophic transfer factor (TTFco'"pos"e). Product of TTF values for all trophic levels.
c - Translated water selenium concentration corresponding to a bird egg criterion element of 11.2 mg Se/kg dw, calculated by
(Equation 5-1).
99
-------
1 1
t A
Cumulative
Proportion
i*
-*1 /
* L'
i >
t A
i
* Lotic
Lentic
A .
I
1 10
Water (|ig/L)
100
Figure 5-3. Probability distribution of the water column concentrations translated from the
bird egg criterion element at the 26 lentic and 39 lotic aquatic sites from U.S. EPA (2016a).
Dashed and dash-dot lines show the 20th percentiles of the lentic and lotic distributions,
respectively.
As in the 2016 national aquatic life criterion for selenium, the EPA presented the 20th
percentile from the distribution of translated water column values of each category as the water
column concentrations (3.0 |ig/L for lotic waters and 1.5 |ig/L for lentic waters) so that a direct
comparison can be made to the aquatic life water-column concentrations, and because the 20th
percentile is consistent with past practice as it provides a high probability of protection for most
aquatic systems in both lentic and lotic categories. Table 5-10 provides the 20th percentile of the
water concentration values translated from the bird egg criterion element value. Since the EPA
translated water column concentration values for aquatic-dependent wildlife for both lentic and
lotic systems are equal to or extremely close (1.5 |ig/L for lentic waters and 3.0 |ig/L for lotic
waters) to the translated water column concentration values for aquatic life (1.5 |ig/L for lentic
waters and 3.1 |ig/L for lotic waters), the EPA's 2016 national selenium aquatic life water
column criterion elements for lentic and lotic waters is expected to be protective of aquatic-
dependent wildlife as well. The differences in the translated water column concentration value
for lotic waters between the aquatic life and aquatic-dependent wildlife are within the range of
uncertainty of the 2016 national selenium water column criterion elements.
100
-------
As discussed in Section 2.2.2 of U.S. EPA (2016a), selenium bioaccumulation potential
depends on several biogeochemical factors that characterize a particular aquatic system.
Uncertainty in the translation of the egg-ovary criterion element to the water column element can
be reduced by deriving a site-specific water column criterion element that uses site-specific
selenium data and information on food web dynamics from a biological assessment of the
aquatic system. The general considerations are provided in the performance-based approach
{Methodfor Translating Selenium Tissue Criterion Elements into Site-specific Water Column
Criterion Elements for California, Version 2 December 2024) and in Appendix K of U.S. EPA
(2016a).
The EPA conducted a separate analysis to run the model with five additional sites where
EFs could be calculated for California waters. The sites are located within two selenium
impacted areas, and when added to the dataset, the translated water column concentrations for
birds changed from 1.5 ng/L to 1.6 ng/L for lentic systems, and remained at 3.0 ng/L for lotic
systems. This analysis was also conducted with the water column criterion elements translated
from fish egg-ovary criterion. After the five California sites were added, the translated lentic
water column concentration increased from 1.5 ng/L to 1.6 ng/L, and remained unchanged at 3.1
Hg/L for lotic systems. A comparison is shown in Table 5-11.
Table 5-10. Water Column Concentration Values Translated from the Bird Egg Criterion
Element Using the 26 Lentic and 39 Lotic Sites in the National Selenium Aquatic Life
Criterion (U.S. EPA 2016a).
Lentic
Lotic
20th percentile
(protective aquatic-dependent wildlife water column value)
1.5 jig/L
3.0 jig/L
Table 5-11. Comparison of 20th Percentile Water Column Concentration Values (jig/L)
Translated from the Fish Egg-Ovary Criterion Element and the Bird Egg Criterion
Element for the 26 Lentic and 39 Lotic Sites from the 2016 Aquatic Life Criteria (ALC)
Dataset and the 65 Sites from the ALC Dataset + 5 Additional California Sites (4 Lentic
and 1 Lotic).
Translation Site Dataset
Translated from
Fish Egg-Ovary
Translated from
Bird Egg
Lentic
Lotic
Lentic
Lotic
26 Lentic and 39 Lotic (2016 ALC Sites)
1.5 |ig/L
3.1 |ig/L
1.5 |ig/L
3.0 |ig/L
65 ALC Sites + 5 CA Sites (4 Lentic and 1 Lotic)
1.6 |ig/L
3.1 |ig/L
1.6 |ig/L
3.0 |ig/L
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5.6 Derivation of Averaging Period for Chronic Water Criterion Element and
Intermittent-Exposure Water Criterion Element
A previous analysis done in U.S. EPA 2016a (see Section 3.2.6 and Appendix J in U.S.
EPA 2016a) demonstrated that a 30-day averaging period for the chronic water criterion element
affords protection under all conditions for fish. The EPA is finalizing the same averaging period
for the water column elements of California's selenium criterion.
Chapman et al. (2009) noted that selenium acute toxicity has been reported rarely in the
aquatic environment and that traditional methods for predicting effects based on direct exposure
to dissolved concentrations do not work well for selenium. As demonstrated in Appendix J of
U.S. EPA (2016a), the kinetics of selenium accumulation and depuration are sufficiently slow
that attainment of the water criterion element concentration by ambient 30-day averages will
protect sensitive aquatic life species even where concentrations exhibit a high degree of
variability.
To address situations where pulsed exposures of selenium could result in
bioaccumulation in the ecosystem and potential chronic effects in aquatic life and aquatic-
dependent wildlife, the EPA is providing an intermittent-exposure water criterion element
concentration intended to limit cumulative exposure to selenium, derived from the chronic 30-
day water criterion element magnitude and from its duration, which was obtained from the
kinetic analysis of Appendix J in U.S. EPA (2016a). That is, the intermittent criterion element is
based on the same kinetic analysis used to derive the water chronic averaging period (30 days).
The 30-day average concentration, C3o-day, is given by (Equation 5-4):
(Equation 5-4)
Where:
fint
Cbkgrnd
Cint
the intermittent spike concentration (|ig/L)
the fraction of any 30-day period during which elevated selenium
concentrations occur
the average daily background concentration occurring during the
remaining time, integrated over 30 days.
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Cy,o-day i s not to exceed the chronic criterion element, \VQC30-day. If the intent is to apply a
criterion element, WQCint, to the intermittent spike concentrations, then replacing Cim with
WQCint and C30-day with WQCso-day in the above equation, and then solving for WQCint yields
(Equation 5-5):
wqc30
-day Cbkgrndi.l fint)
fint
(Equation 5-5)
The equation expresses the intermittent-exposure water criterion element in terms of the
30-day average chronic water criterion element, for a lentic or lotic system, as appropriate, while
accounting for the fraction (in days) of any 30-day period the intermittent spikes occur and for
the concentration background occurring during the remaining time. The reasonable worst-case
assumption inherent in this approach is that selenium bioaccumulation is linear over a very wide
range of concentrations, that is, EF and TTF values do not decrease significantly as
concentrations increase. For more information and examples on the intermittent-exposure water
criterion element, please see Section 3.3 of U.S. EPA (2016a).
WQCint
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Part 6 Aquatic and Aquatic-dependent wildlife Criteria for
Selenium in California's Fresh Waters
The available data indicate that aquatic life and aquatic-dependent wildlife would be
protected from the toxic effects of selenium by applying the following criteria, recognizing that
fish tissue elements and bird egg elements supersede the translated site-specific water elements
(except in special situations, see footnote 4 in Table 6-1), and that the fish egg-ovary elements
supersede all other fish tissue elements:
1. The concentration of selenium in bird eggs does not exceed 11.2 mg/kg, dry weight;
2. The concentration of selenium in the eggs or ovaries of fish does not exceed 15.1 mg/kg,
dry weight;
3. The concentration of selenium (a) in whole body of fish does not exceed 8.5 mg/kg dry
weight, or (b) in muscle tissue of fish (skinless, boneless fillet) does not exceed 11.3
mg/kg dry weight;
4. The 30-day average concentration of selenium in water does not exceed 1.5 |ig/L in lentic
aquatic systems and 3.1 |ig/L in lotic aquatic systems unless or until a site-specific water
column criterion element is derived for a particular waterbody following the
methodology does not exceed described in Methodfor Translating Selenium Tissue
Criterion Elements into Site-specific Water Column Criterion Elements for California,
Version 2 December 2024;
5. The intermittent concentration of selenium in either a lentic or lotic water, as appropriate,
1,1 WQC30-day - Cbkarnd(l~f int) ,1 ,1
does not exceed WQCint = - more than once in three years on
/int
average.
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Table 6-1. Summary of the Final California Selenium Ambient Chronic Water Quality
Criteria for Protection of Aquatic Life and Aquatic-Dependent Wildlife.
Media
Type
Bird Tissue
Fish Tissue1
Water Column4
Criterion
Element
Bird Egg2
Egg-Ovary2
Fish Whole-
Body or
Muscle3
Monthly
Average
Exposure5
Intermittent Exposure6
8.5 mg/kg dw
whole-body
1.5 (ig/L in lentic
aquatic systems
Magnitude
11.2 mg/kg
dw
15.1 mg/kg dw
or
11.3 mg/kg dw
muscle
(skinless,
boneless filet)
3.1 (ig/L in lotic
aquatic systems
WQCint =
WQCzo-day CbkgrndQ fint)
f int
Duration
Instantaneous
measurement7
Instantaneous
measurement7
Instantaneous
measurement7
30 days
Number of days/month with an
elevated concentration
Frequency
Not to be
exceeded
Not to be
exceeded
Not to be
exceeded
Not more than
once in three
years on average
Not more than once in three years
on average
1. Fish tissue criterion elements are expressed as steady-state.
2. Fish egg-ovary supersedes any whole-body, muscle, or water column criterion elements for aquatic life when fish egg-ovaries are
measured, except as noted in footnote 4. Bird egg supersedes water column criterion elements for aquatic-dependent wildlife when
bird eggs are measured, except as noted in footnote 4. The bird tissue criterion element is independently applicable from and
equivalent to the fish tissue criterion elements.
3. Fish whole-body or muscle tissue supersedes the water column criterion elements when both fish tissue and water concentrations
are measured, except as noted in footnote 4.
4. Water column criterion elements are based on dissolved total selenium in water and are derived from fish tissue and bird tissue
criterion elements via bioaccumulation modeling. When selenium inputs are increasing, water column criterion elements are the
applicable criterion elements in the absence of steady-state condition fish tissue or bird tissue data.
5. The water column criterion element, which applies independently to the respective aquatic life and aquatic-dependent wildlife uses,
is applicable for all CWA purposes and consists of a water column value of 1.5 |ig/L in lentic aquatic systems and 3.1 |ig/L in lotic
aquatic systems unless or until a site-specific water column criterion element is derived for a particular waterbody following the
methodology described in Method for Translating Selenium Tissue Criterion Elements into Site-specific Water Column Criterion
Elements for California, Version 2 December 2024. This publication is incorporated by reference into this section with the approval
of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 5 1. All approved material is available at EPA, OW
Docket, EPA West, Room 3334, 1301 Constitution Ave., NW, Washington, DC, 20004, (202) 566-2426. It is also available for
inspection at the National Archives and Records Administration (NARA). For information on the availability of this material at
NARA, call 202-741 -6030 or go to www.arcliives.gov/federal-register/cfr/ibr-locations.html.
6. Where WQC3o-day is the applicable water column monthly criterion element, Cbkgmd is the average background selenium
concentration, and fmt is the fraction of any 30-day period during which elevated selenium concentrations occur, with fmt assigned a
value >0.033 (corresponding to 1 day).
7. Fish tissue and bird tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over
time and space in bird or fish population(s) at a given site.
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The chronic selenium criterion is derived to be protective of the entire aquatic
community, including fish, amphibians, invertebrates, and aquatic-dependent wildlife. Based on
this analysis and the EPA's previous work in U.S. EPA (2016a), fish and birds are the most
sensitive taxa to selenium effects. When both endpoints are translated to protective lentic and
lotic water column concentration, the results are equal or nearly equal. Selenium water quality
criterion elements based on fish tissue (egg-ovary, whole body, and/or muscle) or bird egg
sample data override the criterion elements based on water column selenium data due to the fact,
noted above, that fish and bird tissue concentrations provide the most robust and direct
information on potential selenium effects in fish and birds. However, because selenium
concentrations in fish and bird tissue are a result of selenium bioaccumulation via dietary
exposure, there are two specific circumstances where the fish concentrations do not fully
represent potential effects on fish and the aquatic ecosystem: 1) in "fishless" waters for the fish
tissue elements, and 2) in areas with new selenium inputs for both taxa.
Fishless waters are defined as waters with insufficient instream habitat and/or flow to
support a population of any fish species on a continuing basis, or waters that once supported
populations of one or more fish species but no longer support fish (i.e., extirpation) due to
temporary or permanent changes in water quality (e.g., due to selenium pollution), flow or
instream habitat. Because of the inability to collect sufficient fish tissue to measure selenium
concentrations in fish in such waters, water column concentrations will best represent selenium
levels required to protect aquatic communities and downstream waters in such areas. It is
possible that birds will still represent potential effects of selenium in these fishless waters. As
shown in Part 5 of this TSD, some birds that consume invertebrates bioaccumulate more
selenium than birds that eat primarily fish and may therefore more susceptible to selenium
effects.
Footnote 1 in Table 6-1 indicates that the fish tissue concentrations of the criterion are
expressed as steady-state. Since avian taxa are more mobile across aquatic habitats, the bird
tissue concentrations of the criterion are not expressed in terms of steady-state. An organism is in
steady-state when the rates of chemical uptake and depuration are equal and tissue
concentrations remain constant over time (U.S. EPA 2003). For the purposes of EPA's 2016
recommended aquatic life selenium criterion, steady-state refers to conditions where sufficient
time has passed after the introduction of a new or increased discharge of selenium into a water
106
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body so that fish tissue concentrations of selenium are no longer increasing (U.S. EPA 1991).
For a fish tissue measurement to be meaningful, the system from which the sample is taken
should not be experiencing recent new inputs of selenium. In the EPA's Aquatic Life Ambient
Water Quality Criterion for Selenium-Freshwater 2016, new inputs are defined as new
anthropogenic activities resulting in the release of selenium into a lentic or lotic aquatic system.
New inputs do not refer to seasonal variability of selenium that occurs naturally within a system
(e.g., spring run-off events or precipitation-driven pulses). New inputs will likely result in a
greater concentration of selenium in the food web and a relatively slow increase in the selenium
concentration in fish. Fish tissue data should not be utilized for implementation of the criterion
until after selenium concentrations in the fish have stopped increasing. The EPA estimates that
the concentration of selenium in fish tissue will not reach steady-state for several months in lotic
systems and for longer time periods (e.g., 2-3 years) in lentic systems. Achievement of steady-
state in an aquatic system depends on the hydrodynamics of the aquatic system (particularly
reservoirs with multiple riverine inputs and controlled releases of water into downstream water
bodies), the location of the selenium input, and the particular food web. The EPA expects the
time needed to achieve steady-state with new or increased selenium inputs to be site-specific.
Thus, the EPA recommends that fish tissue criterion elements not take precedence over the water
column criterion elements until the aquatic system achieves steady-state. In the interim, the EPA
recommends sampling and using site-specific data to gain a better understanding of the selenium
bioaccumulation dynamics in a receiving water and to determine when steady-state conditions
have been reached.
Additionally, given that the chronic selenium criterion is derived to be protective of the
entire aquatic community, fish tissue and bird tissue elements were independently derived and an
analysis was conducted to determine if the fish tissue elements would be protective of aquatic-
dependent birds or vice versa (Appendix D). In this analysis, measured bird and fish tissue
selenium concentrations were used to indicate if one criterion element would be protective of the
other. In the analysis presented in Appendix D, the proportion of sites where both bird and fish
attain their respective criterion is higher in lotic sites than lentic sites, and the proportion of sites
where birds attain but fish do not is higher in lentic sites than in lotic sites. It is unclear if these
lentic-lotic differences represent a general result or are unique to these studies. Despite these
differences, the general result that the bird egg criterion will most likely be met so long as the
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fish tissue criterion is attaining, but the fish tissue criterion will not necessarily be met if the bird
criterion is attaining, applies to both lentic and lotic waterbodies. However, as summarized in
Part 1 of the TSD, the EPA derived the bird tissue criterion element in order to protect aquatic-
dependent wildlife under California's wildlife designated uses. The national selenium criterion
does not incorporate protections for aquatic-dependent wildlife, and the fish tissue criterion was
not intended to ensure the protection of aquatic-dependent wildlife. Therefore, to ensure that
both aquatic life and aquatic-dependent wildlife in California are protected, the EPA determined
that the fish tissue and bird tissue criterion values should be stand-alone elements and that one
should not override the other.
6.1 Protection of Downstream Waters
EPA regulations at 40 CFR § 131.10(b) provide that "[i]n designating uses of a
waterbody and the appropriate criteria for those uses, the state shall take into consideration the
water quality standards of downstream waters and ensure that its water quality standards provide
for the attainment and maintenance of the water quality standards of downstream waters."
Especially in cases where downstream waters are lentic waterbody types (e.g., lakes,
impoundments), or harbor more sensitive species, a selenium criterion more stringent than that
required to protect in-stream uses may be necessary to ensure that water quality standards
provide for the attainment and maintenance of the water quality standards of downstream waters.
6.2 Site-specific Criteria
All elements of the final California selenium criterion may be modified to reflect site-
specific conditions where the scientific evidence indicates that different values will be protective
of aquatic life and aquatic-dependent wildlife and provide for the attainment of designated uses.
Since the fish egg-ovary criterion element is based on a robust set of toxicity data,
California may modify that element by applying the Recalculation Procedure (U.S. EPA 2013) to
modify the species toxicity database to reflect taxonomic relatedness to the site assemblage,
while including tested surrogates for untested resident species. If the Recalculation Procedure is
used, the State will follow the process to develop a site-specific criterion instead of the
performance-based approach. For aquatic-dependent wildlife, the Recalculation Procedure would
not be appropriate as the bird tissue criterion element was derived for the most sensitive bird
species in the literature and is considered a surrogate for all birds. However, under the
108
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performance-based approach, California could translate the bird ECio to a site-specific water
column criterion with the use of a species-specific TTF if site-specific data indicated this was
needed to ensure protection of aquatic-dependent wildlife.
It is important to note that species in the data set presented here that are not present at a
site should not be deleted from the data set if those species serve as surrogate(s) for other species
known or expected to be present at a site. To further improve confidence in the applied tissue
criterion element, further testing of fish species or bird species that are residents at the site can be
conducted. The most relevant testing would measure survival and occurrence of deformities in
offspring of wild-caught female fish, or hatching success of wild breeding bird pairs to determine
an ECio for selenium in the eggs or ovaries (e.g., following Janz and Muscatello 2008). For
development of a site-specific criteria following a PBA approach, using either the final bird egg,
fish egg-ovary, fish whole body, or fish muscle criterion concentration element or a site-specific
bird egg, fish egg-ovary, fish whole body, or fish muscle criterion element, translation of a tissue
criterion to a protective water concentration should be performed in a manner that accounts for
site-specific conditions and is consistent with the performance-based approach (Methodfor
Translating Selenium Tissue Criterion Elements into Site-specific Water Column Criterion
Elements for California, Version 2, December 2024; U.S. EPA 2024a). Both the performance-
based approach (Methodfor Translating Selenium Tissue Criterion Elements into Site-specific
Water Column Criterion Elements for California, Version 2 December 2024; U.S. EPA 2024a)
and Appendix K in U.S. EPA (2016a) provide information on the data necessary to derive a site-
specific water column criterion element translated from the fish and bird tissue criterion elements
and a site-specific criterion, as well as scientifically defensible methods, including the use of
traditional Bioaccumulation Factors (BAFs), in addition to the more comprehensive mechanistic
modeling used in the criteria derivation in this TSD.
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Appendix A Summary Information for Quantitative and
Qualitative Bird Studies
Summary
The following three tables include summary information from the studies considered for
the derivation of the aquatic-dependent wildlife egg criterion described in Part 4. Table A-l
summarizes the three mallard studies that were combined to calculate the mallard egg EC 10 in
Part 4.2.1. Table A-2 summarizes bird studies with reproductive endpoints that provided
qualitative support for the final egg tissue criteria described in Part 4.6.1. Table A-3 summarizes
bird studies with non-reproductive endpoints that provided qualitative support for the final egg
tissue criteria described in Section 4.6.2.
A-l
-------
Table A-l. Quantitative aquatic-dependent wildlife toxicity data considered and used for criterion development.
Data from these studies were combined into a meta-analysis with a resulting ECio for egg hatchability of 11.2 ms egg/kg dw.
Species,
Life Stage
Animal
Origin/Site
Maternal
Age
Chemical
Form
Exposure
Media Type
and Duration
Selected
Sensitive
Endpoint or
Effect
Toxicity Value
Reference
Diet
mg/kg ww
Egga
mg/kg dw
Anseriformes (Ducks, Geese, and Swans)
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
2 years old
Seleno- DL-
methionine
Dietary (3 week
pre- breeding
exposure
through end of
egg laying)
Hatchability
NOEC:
Controlb
LOEC: 10b
NOEC: 0.17
LOEC: 15.9
Heinz et al. 1987
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
2 years old
Seleno- DL-
methionine
Dietary
(Duration not
specified, but
>100 days.)
Hatchability
NOEC: 8b
LOEC: 16b
NOEC: 36.7
LOEC: 60
Heinz et al. 1989
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
(Outdoorsman
Hunting Club,
Webb, IA)
1 year old
Seleno- DL-
methionine
Dietary
120-122 days
Hatchability
NOEC: 3.5b
LOEC: 7b
NOEC: 12.1
LOEC: 24.5
Stanley et al. 1996
a All egg concentrations are measured from a subset of eggs
b Nominal
0 Measured
A-2
-------
Table A-2. Qualitative aquatic-dependent wildlife toxicity reproductive data considered for criterion development.
Species,
Life Stage
Animal
Origin/Site
Maternal
Age
Chemical
Form
Exposure
Media Type
and Duration
Selected
Sensitive
Endpoint or
Effect
Toxicity Value
Reference
Diet mg/kg
WW
Egga mg/kg
dw
Anseriformes (Ducks, Geese, and Swans)
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
Not specified
Seleno- DL-
methionine
Dietary
(4 week pre-
breeding
exposure
through end of
egg laving)
Hatchability
NOEC:
controlb
LOEC: 10b
NOEC: 1.35
LOEC: 30.4
Heinz and
Hoffman 1996
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
18 month old
(Whistling
Wings,
Hanover, 11)
Seleno- DL-
methionine
Dietary
(4 week pre-
breeding
exposure
through end of
egg laying)
Hatchability
NOEC:
>10b
NOEC: >25.1
Heinz and
Hoffman 1998
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
(Frost
Waterfowl
Trust, Coloma,
WI)
1 year old
Seleno- DL-
methionine
Dietary
21 weeks
onset of egg-
laying
NOEC:
controlb
LOEC: 15b
Heinz and
Fitzgerald 1993a
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
2 years old
selenite
Dietary
Duration not
specified, but
>100 davs
percentage of
abnormal
embryos0
NOEC: 5b
LOEC: 10b
NOEC: 0.6
LOEC: 1.77
Hoffman and
Heinz 1988
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
2 years old
Seleno- DL-
methionine
Dietary
Duration not
specified, but
>100 days
percentage of
malformed
embryos0
NOEC: 4b
LOEC: 8b
NOEC: 11.3
LOEC: 36.7
A-3
-------
Species,
Life Stage
Animal
Origin/Site
Maternal
Age
Chemical
Form
Exposure
Media Type
and Duration
Selected
Sensitive
Endpoint or
Effect
Toxicity Value
Reference
Diet mg/kg
WW
Egga mg/kg
dw
Mallard,
Anas
platwhvnchos,
Adult '
Game farm
(Frost
Waterfowl
Trust, Coloma,
WI)
1 year old
Seleno- DL-
methionine
Dietary
115-124 days
Hatchability
NOEC:
0.37 (dw)
LOEC: 6.5
(dw)
NOEC: 1.6
LOEC: 42
Stanley et al.
1994 '
Pelecaniformes (Pelicans, Herons, Ibises, and Allies)
Black-crowned
night heron,
Nvcticorax
nvcticorax
Adult
Obtained from
captive
breeding
colony.
Patuxent
Wildlife
Center. Laurel,
MD
Not specified
Seleno- DL-
methionine
Hatchability,
Malformations
NOEC:
>10b
NOEC: >3.3
(ww)
Smith et al 1988
Strigiformes (Owls)
Eastern
screech owl.
Mega scops
asio
Adult
Captive birds
3-4 years old
Seleno- DL-
methionine
(measured
in egg and
diet)
Dietary
Duration not
specified.
Through
clutch
completion.
Nestling
survival to 5 d
Adult weight
NOEC:
8.8 ld (dw)
LOEC: 30d
(dw)
NOEC: 2.57
(ww)
LOEC: 7.44
(ww)
Wiemeyer and
Hoffman 1996
A-4
-------
Species.
I.ile S(;i»c
Aniiiiiil
Oriiiin/Siie
Miileniiil
A lie
( hcmic;il
l-o nil
Kxposurc
Medisi l>pe
iiiid Dui'iilioii
Selected
Sensitive
r.ndpoinl or
I'.ITecl
To\icil\ Y;iliic
Ucl'crcncc
Did mii/kii
MM
I-- lili'1 mii/kii
dM
Charadriiformes (Plovers, Sandpipers, and Allies)
American
avocet,
Recurvirostra
americana
Eggs and
nestlings of
field-exposed
adults
Collected eggs
from north and
south Tulare
Lake drainage
district, CA;
and
Westfarmers,
CA
n/a (field
collected
eggs)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
Chick weight
n/a
NOEC: 6.7
LOEC: 31.4
(weights were
7% lower at
high Se site
vs. low Se site
(3.3 mg/kg dw
egg)
Hoffman et al.
2002
Black necked
stilt;
Himantopus
mexicanus
Eggs and
nestlings of
field-exposed
adults
Collected eggs
from north and
south Tulare
Lake drainage
district, CA;
and
Westfarmers,
CA
n/a (field
collected
eggs)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
Chick weight
n/a
NOEC: >20.5
(no
differences
across sites)
Hoffman et al.
2002
Black necked
stilt;
Himantopus
mexicanus
Eggs and
nestlings of
field-exposed
adults
Collected eggs
from
Kesterson
Res., Salton
Sea, Tulare
Basin, and
Volta State
Wildlife Area,
CA.
n/a (field
collected
eggs)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
Nest inviability
Egg inviability
n/a
ECio: 16.0
(nest
inviability)
ECio: 20.9-
31.0 (egg
inviability)
Adams et al.
2003; Skorupa
1998b
A-5
-------
Species,
Life Stage
Animal
Origin/Site
Maternal
Age
Chemical
Form
Exposure
Media Type
and Duration
Selected
Sensitive
Endpoint or
Effect
Toxicity Value
Reference
Diet mg/kg
WW
Egga mg/kg
dw
Spotted
sandpiper,
Actitis
macularia
Eggs and
nestlings of
field-exposed
adults
5 reference
and 3 Se
exposed areas
in S. Alberta,
CA
n/a (nest
observations)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
Fledglings per
nest.
n/a
NOEC: >7.3
Harding et al.
2005
Passeriformes (Perching Birds)
Tree swallows,
Tachycineta
bicolor
Eggs and
nestlings of
field-exposed
adults
1 reference site
and four Se
impacted sites
near Key
Lake, northern
Saskatchewan
n/a (nest
observations)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
Mean clutch
size
Hatchability
Nestling growth
n/a
NOEC: >13.3
(Maximum
egg
concentration
at site with
highest Se.)
Weech et al.
2012
Tree swallows,
Tachycineta
bicolor
Eggs and
nestlings of
field-exposed
adults
Watts Bar
Reservoir, TN
(6 impacted
sites and one
reference site)
n/a (nest
observations)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
Hatching
success
n/a
NOEC:> 4.75e
Walls et al. 2015
Red-winged
blackbirds,
Agelaius
phoenicens
Eggs and
nestlings of
field-exposed
adults
Elk River
Valley, SE
British
Columbia
n/a (nest
observations)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
Hatchability
n/a
NOEC: 22
Point of
downward
inflection of
quadratic
curve/
Harding 2008
A-6
-------
Species,
Life Stage
Animal
Origin/Site
Maternal
Age
Chemical
Form
Exposure
Media Type
and Duration
Selected
Sensitive
Endpoint or
Effect
Toxicity Value
Reference
Diet mg/kg
WW
Egga mg/kg
dw
Red-winged
blackbirds,
Agelaius
phoenicens
Eggs and
nestlings of
field-exposed
adults
SE Idaho in
the vicinity of
Soda Springs
n/a (nest
observations)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
All measured
endpoints (nest
success, clutch
size, chicks
hatched/fledged,
egg/hatchling
weight)
n/a
NOEC:>7.18
Ratti et al. 2006
American
robin, Turdus
migratorius
Eggs and
nestlings of
field-exposed
adults
SE Idaho in
the vicinity of
Soda Springs
n/a (nest
observations)
Naturally
occurring Se
Field
exposure.
Lifetime
maternal
exposure.
All measured
endpoints (nest
success, clutch
size, chicks
hatched/fledged,
egg/hatchling
weight)
n/a
NOI-C: 4.48
Ratti et al. 2006
a All egg concentrations are measured from a subset of eggs
b Nominal
0 Abnormal embryos include those with malformations, edema, or stunted growth. Malformed embryos do not include those with edema.
d Measured
e Hatching success was significantly lower at two of the six impacted sites compared to reference. However, differences could not be attributable to Se because of
multiple potential co-contaminants. No combinations of potential contaminants could explain the differences in hatching success.
f Not statistically significant.
A-7
-------
Table A-3. Qualitative aquatic-dependent wildlife toxicity non-reproductive data
considered for criterion development.
Species,
Life Stage
Animal
Origin/Site
Chemical
Form
Exposure
Media Type
and Duration
Selected
Sensitive
Endpoint or
Effect
Toxicity
Value of
Diet mg/kg
WW
Reference
Anseriformes (Ducks, Geese, and Swans)
Mallard,
Anas
platyrhynchos,
Adult males
Game farm
Seleno- DL-
methionine
Dietary
16 weeks
Number of
molts
completed by
16 weeks
NOEC: 20a
LOEC: 40a
Albers 1996
Lesser Scaup,
Avthva affmis
Adult
Captive-reared
Seleno- DL-
methionine
Dietary
4 months
Survival
Weight
NOEC:
>20.7b (dw)
Brady et al. 2013
Lesser Scaup,
Avthva affmis
Adult
Captive-reared
Seleno- DL-
methionine
Dietary
30 days
Survival
NOEC:
>14.9b (dw)
DeVink et al.
2008
Mallard,
Anas
platyrhynchos,
1-day old
hatchlings
Game farm
(Spring Farm,
Sag Harbor,
NY)
Selenite
Dietary
6 weeks
Survival
Weight
NOEC: 20a
LOEC: 40a
Heinz et al. 1988
Mallard,
Anas
platyrhynchos,
1-day old
hatchlings
Game farm
(Spring Farm,
Sag Harbor,
NY)
Seleno- DL-
methionine
Dietary
6 weeks
Survival
Weight
NOEC: 20a
LOEC: 40a
Mallard,
Anas
platyrhynchos,
Adult males
Game farm
(Frost
Waterfowl
Trust, Coloma,
WI)
Seleno- DL-
methionine
Dietary
21 weeks+12
weeks all
control+5
weeks0
Survival
Weight
NOEC:>15ad
Heinz 1993
Mallard,
Anas
platyrhynchos,
Adult males
Game farm
(Frost
Waterfowl
Trust, Coloma,
WI)
Seleno- DL-
methionine
Dietary
16 weeks
Survival
Weight
NOEC: 10a
LOEC: 20a
Heinz and
Fitzgerald 1993b
A-8
-------
Species.
I.ile S(;i»c
Aniiiiiil
Oriiiin/Siie
( hcmic;il
l-o rm
Mxposuiv
Mcdi.i Tjpe
iiiul l)iir;iliun
Selected
Sensitive
I'lndpoim or
r.lTecl
To\icil>
\ ;iluc «l"
Diel
\\ \\
Ucl'crcncc
Mallard,
Anas
platyrhynchos,
1-day old
hatchlings
Game farm
(Oak Ridge
Game Farm,
Gravette, AR)
Seleno- DL-
methionine
Dietary
4 weeks
Weight
(standard-
22%-protein
diet)
NOEC: 15a
LOEC: 60a
Mallard,
Anas
platyrhynchos,
1-day old
hatchlings
Game farm
(Oak Ridge
Game Farm,
Gravette, AR)
Seleno- DL-
methionine
Dietary
4 weeks
Survival (low-
11%-protein
diet)
NOEC: 15a
LOEC: 60a
Hoffman et al.
1992
Mallard,
Anas
platyrhynchos,
1-day old
hatchlings
Game farm
(Oak Ridge
Game Farm,
Gravette, AR)
Seleno- DL-
methionine
Dietary
4 weeks
Weight (high-
44%-protein
diet)
NOEC:
control3
LOEC: 15a
Mallard,
Anas
platyrhynchos,
Flightling
males
Game farm
(Whistling
Wings, Inc.,
Hanover, 11)
Seleno- DL-
methionine
Dietary
150 days
Alopecia
Food
consumption
NOEC: 10a
LOEC: 25a
O'Toole and
Raisbeck 1997
Falconiformes (Falcons and Caracaras)
American
kestrel, Falco
sparverius
Adult
Captive-reared
(McGill
University,
Montreal,
Quebec)
Seleno- DL-
methionine
Dietary
77 days
Lean mass 49
d after end of
exposure6
NOEC: 6.3b
(dw)
LOEC: 12b
(dw)
Yamamoto and
Santolo 2000
a nominal
b measured
0 treatment group fed 15 mg/kg Se for 21 weeks, then control diet for 12 weeks, then both groups fed 100 mg/kg Se
for 5 weeks.
d No effects at 15 mg/kg diet from the initial 21-week exposure.
e Weights were not measured prior to Se exposure. No statistically significant differences in mass on final day of
exposure.
A-9
-------
Appendix B
Calculation of Trophic Transfer Factors
Paired Data Used to Calculate Bird Trophic Transfer Factors (TTF)
As described in Part 5.4.2.1, the EPA searched its collection of available selenium
measurements and identified measurements taken from aquatic organisms or aquatic-dependent
birds. For each measurement from an aquatic organism or bird, the EPA searched for additional
measurements from other aquatic organisms or particulate material that was collected from the
same aquatic site and of a type deemed likely to be ingested as a food source or in conjunction
with feeding activity (i.e., lower trophic level). If multiple lower trophic level measurements for
the same food type were matched to an aquatic organism or bird measurement, the median
measurement for that food type was calculated. If multiple lower trophic level measurements for
two or more food types were matched to an aquatic organism or bird measurement, the median
measurement of those food types was calculated. For bird species whose diet consisted of both
plants and animals, information regarding species-specific dietary descriptions was used to
calculate the relative proportions of the bird diet consisting of plants and animals. For every egg
selenium measurement paired with additional selenium measurements from both aquatic
invertebrates and aquatic algae and vascular plants, a weighted dietary (plant+animal) selenium
concentration was calculated for every site where an egg selenium measurement was paired with
both a plant and animal selenium measurement, as follows.
Diet Se = (Plant Se x Plant Diet Proportion) + (Animal Se x Animal Se Proportion)
In order to be considered, paired data were required to be collected at the same site within
a one-year period. The one-year period for matched data is based on an analysis described in
U.S. EPA (2016a) suggesting the relationship between selenium in paired tissue is insensitive to
collection time within one year.
The relationship between paired egg and weighted diet selenium concentrations was
evaluated using linear regression following natural log transformation after removing outliers.
For each regression model, outliers were identified by examining four residual plots: residual vs.
fitted values; standardized residuals vs. theoretical quantiles (Q-Q plot); square root of
standardized residuals vs. fitted values; and standardized residuals vs. leverage (Cook's
B-l
-------
distance). An observation was identified as an outlier or overly influential if the observation was
greater than the 50th percentile in the Cook's distance plot, or if it was identified as an outlier in
three of the four plots listed above. Up to three passes of this outlier analysis was performed for
each regression model, after removing outliers from previous passes. If the slope of a set of
matched pairs of selenium measurements was both positive and statistically significant (P<0.05),
then the relationship between selenium in the target bird species and the food it consumes is
considered adequately represented by the available data.
The following tables (Table B-l through Table B-8) list the paired data used to calculate
bird TTF values and the linear regression model results. The "Median TTF' reported at the
bottom of each of these figures is the species level TTF shown in Table 5-3. These species level
TTF are incorporated into the food web models described below, which were used to calculate
the bird composite TTFs shown in Table 5-5.
B-2
-------
Table B-l. American Avocet Trophic Transfer Factor (TTF).
Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
4.2
1.81
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
4
1.72
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.5
1.51
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
4.2
1.81
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.2
1.38
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.5
1.51
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.8
1.64
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.5
1.51
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.5
1.51
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
4
1.72
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.4
1.46
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
4.3
1.85
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
4.9
2.11
Lambing et al. 1994
B-23
1.80
0.13
2.40
0.87
2.32
3.4
1.46
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
3.1
0.78
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
2.8
0.70
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
3.9
0.98
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
3.8
0.95
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
3.1
0.78
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
3.6
0.90
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
11
2.76
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
2.8
0.70
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
3.5
0.88
B-3
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
3.6
0.90
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
4.2
1.05
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
4.2
1.05
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
2.8
0.70
Lambing et al. 1994
B-26
8.90
0.13
3.25
0.87
3.98
2.9
0.73
Lambing et al. 1994
B-27
1.80
0.13
2.10
0.87
2.06
2.7
1.31
Lambing et al. 1994
B-27
1.80
0.13
2.10
0.87
2.06
2.7
1.31
Lambing et al. 1994
B-27
1.80
0.13
2.10
0.87
2.06
2.6
1.26
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
3.1
1.95
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
2.8
1.76
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
2.2
1.38
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
2.7
1.70
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
2.7
1.70
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
4.1
2.58
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
1.6
1.01
Lambing et al. 1994
B-29
1.20
0.13
1.65
0.87
1.59
3.9
2.45
Rinella and Schuler
1992
Harney
0.51
0.13
1.55
0.87
1.42
1.3
0.92
Rinella and Schuler
1992
Harney
0.51
0.13
1.55
0.87
1.42
2
1.41
Rinella and Schuler
1992
Harney
0.51
0.13
1.55
0.87
1.42
2.1
1.48
Rinella and Schuler
1992
Harney
0.51
0.13
1.55
0.87
1.42
1.5
1.06
Rinella and Schuler
1992
N Malheur
0.56
0.13
2.20
0.87
1.99
0.87
0.44
B-4
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Rinella and Schuler
1992
N Malheur
0.56
0.13
2.20
0.87
1.99
1.9
0.96
Rinella and Schuler
1992
N Malheur
0.56
0.13
2.20
0.87
1.99
3.1
1.56
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.5
1.30
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.7
1.48
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.4
1.22
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.6
1.39
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.13
1.13
0.87
1.08
3.15
2.92
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.13
1.13
0.87
1.08
2.8
2.59
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.13
1.13
0.87
1.08
2.86
2.65
B-5
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Median TTF
Adjusted r2
df
B-6
-------
Table B-2. American Coot Trophic Transfer Factor (TTF).
Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler et al. 1991
7
10.72
0.8
31.75
0.2
14.93
11.1
0.74
Butler etal. 1995
XT
0.41
0.8
1.33
0.2
0.59
1.1
1.86
Butler et al. 1995
TT
0.41
0.8
1.33
0.2
0.59
2.4
4.06
Butler etal. 1997
DCP1
1.45
0.8
6.45
0.2
2.45
8.2
3.35
Butler et al. 1997
DCP1
1.45
0.8
6.45
0.2
2.45
18
7.35
Butler etal. 1997
DCP1
1.45
0.8
6.45
0.2
2.45
8.6
3.51
Butler etal. 1997
DCP1
1.45
0.8
6.45
0.2
2.45
9.7
3.96
Butler etal. 1997
DCP1
1.45
0.8
6.45
0.2
2.45
8.7
3.55
Butler etal. 1997
MNP2
3.85
0.8
4.40
0.2
3.96
8.1
2.05
Butler et al. 1997
MNP2
3.85
0.8
4.40
0.2
3.96
3.6
0.91
Butler etal. 1997
MNP2
3.85
0.8
4.40
0.2
3.96
6.9
1.74
Butler etal. 1997
MNP2
3.85
0.8
4.40
0.2
3.96
8.4
2.12
Butler etal. 1997
MNP2
3.85
0.8
4.40
0.2
3.96
7.5
1.89
Butler etal. 1997
MNP2
3.85
0.8
4.40
0.2
3.96
8.4
2.12
Lambing 1988
7
0.47
0.8
6.50
0.2
1.68
1.4
0.84
Lambing 1988
7
0.47
0.8
6.50
0.2
1.68
1.6
0.95
Lambing 1988
7
0.47
0.8
6.50
0.2
1.68
1.1
0.66
Lambing et al. 1994
B-21
1.42
0.8
4.38
0.2
2.01
5.9
2.94
Lambing et al. 1994
B-21
1.42
0.8
4.38
0.2
2.01
2.6
1.29
Lambing et al. 1994
B-21
1.42
0.8
4.38
0.2
2.01
5
2.49
Lambing et al. 1994
B-21
1.42
0.8
4.38
0.2
2.01
3.8
1.89
Lambing et al. 1994
B-21
1.42
0.8
4.38
0.2
2.01
5.2
2.59
Lambing et al. 1994
B-21
1.42
0.8
4.38
0.2
2.01
3.6
1.79
B-7
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-22
B-22
B-22
B-22
B-22
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
Plant Se
(mg/kg)
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.00
1.00
1.00
1.00
1.00
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.77
Plant
Diet
Prop.
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
Invert. Se
(mg/kg)
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
3.15
3.15
3.15
3.15
3.15
4.20
4.20
4.20
4.20
4.20
4.20
4.20
4.20
4.20
4.20
4.20
Invert
Diet
Prop.
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
Diet Se
(mg/kg)
2.01
2.01
2.01
2.01
2.01
2.01
2.01
2.01
2.01
1.43
1.43
1.43
1.43
1.43
1.46
1.46
1.46
1.46
1.46
1.46
1.46
1.46
1.46
1.46
1.46
B-8
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-26
0.77
0.8
4.20
0.2
1.46
2.6
1.78
Lambing et al. 1994
B-26
0.77
0.8
4.20
0.2
1.46
2.1
1.44
Lambing et al. 1994
B-26
0.77
0.8
4.20
0.2
1.46
3
2.05
Lambing et al. 1994
B-26
0.77
0.8
4.20
0.2
1.46
1.8
1.23
Lambing et al. 1994
B-26
0.77
0.8
4.20
0.2
1.46
1.8
1.23
Peterson et al. 1991
3
4.64
0.8
9.62
0.2
5.64
10.3
1.83
Peterson et al. 1991
3
4.64
0.8
9.62
0.2
5.64
13.1
2.32
Rinella and Schuler
1992
N Malheur
0.56
0.8
2.20
0.2
0.89
1.8
2.03
Rinella and Schuler
1992
N Malheur
0.56
0.8
2.20
0.2
0.89
1.5
1.69
Rinella and Schuler
1992
N Malheur
0.56
0.8
2.20
0.2
0.89
1.4
1.58
Rinella and Schuler
1992
N Malheur
0.56
0.8
2.20
0.2
0.89
1.5
1.69
Rinella and Schuler
1992
S Malheur
0.82
0.8
1.20
0.2
0.90
1.3
1.45
Rinella and Schuler
1992
S Malheur
0.82
0.8
1.20
0.2
0.90
1
1.12
Rinella and Schuler
1992
S Malheur
0.82
0.8
1.20
0.2
0.90
1.8
2.01
Rinella and Schuler
1992
S Malheur
0.82
0.8
1.20
0.2
0.90
1.8
2.01
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.8
1.13
0.2
0.85
1.8
2.13
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.8
1.13
0.2
0.85
1.73
2.05
B-9
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Rinellaetal. 1994
Ft. Boise
WMA
0.78
0.8
1.13
0.2
0.85
1.85
2.19
Median TTF
1.89
3
2.5
$ 2
~o *¦
O)
1.5
O)
O) 1
d) 1
d)
CO
c 0.5
0
-0.5
-1
\
~ X
Adjusted r2
0.80
F
232.7
df
58
Y ~
P
<0.001
J t ~
v-^ *
-0.5 0 0.5 1 1.5 2
In Se diet mg/kg dw
B-10
-------
Table B-3. Cinnamon Teal Trophic Transfer Factor (TTF).
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1997
CHP
3.75
0.42
12.00
0.58
8.54
20
2.34
Butler etal. 1997
DCP3
2.10
0.42
7.20
0.58
5.06
5.7
1.13
Butler etal. 1997
DCP3
2.10
0.42
7.20
0.58
5.06
6.1
1.21
Butler etal. 1997
MNP2
3.85
0.42
4.40
0.58
4.17
11
2.64
Rine 11a etal. 1994
Ft. Boise
WMA
0.78
0.42
1.13
0.58
0.98
1.75
1.79
Median TTF
1.79
3.4
2.9 *
1 2.4
O)
I1-9 t
CD
S? 1.4
0)
(J) /
C 0.9
0.4
-0.1
-0.1 0.4 0.9 1.4 1.9 2.4 2.9 3.4
In Se diet mg/kg dw
Adjusted r2
0.76
F
13.81
df
3
P
0.034
B-ll
-------
Table B-4. Eared Grebe Trophic Transfer Factor (TTF).
Because eared grebes eat a 100% invertebrate diet, all paired invertebrate-egg measurements were used, regardless of whether a paired
plant measurement was available.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-16
n/a
0
4.80
1
4.80
13
2.71
Lambing et al. 1994
B-16
n/a
0
4.80
1
4.80
18
3.75
Lambing et al. 1994
B-16
n/a
0
4.80
1
4.80
16
3.33
Lambing et al. 1994
B-16
n/a
0
4.80
1
4.80
11
2.29
Lambing et al. 1994
B-16
n/a
0
4.80
1
4.80
10
2.08
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
17
3.04
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
12
2.14
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
14
2.50
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
12
2.14
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
14
2.50
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
15
2.68
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
10
1.79
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
11
1.96
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
12
2.14
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
13
2.32
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
16
2.86
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
17
3.04
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
15
2.68
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
18
3.21
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
17
3.04
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
12
2.14
Lambing et al. 1994
B-19
n/a
0
5.60
1
5.60
17
3.04
B-12
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
B-19
B-19
B-19
B-19
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
5.60
5.60
5.60
5.60
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
8.90
8.90
8.90
8.90
8.90
8.90
8.90
5.60
5.60
5.60
5.60
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
8.90
8.90
8.90
8.90
8.90
8.90
8.90
B-13
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
B-21
B-21
B-21
B-21
B-21
B-21
B-23
B-23
B-23
B-23
B-23
B-23
B-23
B-23
B-23
B-23
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
8.90
8.90
8.90
8.90
8.90
8.90
3.79
3.79
3.79
3.79
3.79
3.79
3.79
3.79
3.79
3.79
5.50
5.50
5.50
5.50
5.50
5.50
5.50
5.50
5.50
8.90
8.90
8.90
8.90
8.90
8.90
3.79
3.79
3.79
3.79
3.79
3.79
3.79
3.79
3.79
3.79
5.50
5.50
5.50
5.50
5.50
5.50
5.50
5.50
5.50
B-14
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-26
n/a
0
5.50
1
5.50
11
2.00
Lambing et al. 1994
B-26
n/a
0
5.50
1
5.50
7.5
1.36
Lambing et al. 1994
B-26
n/a
0
5.50
1
5.50
5.5
1.00
Median TTF
2.00
3.5
3
s
T3
D)
I2'5
O)
cn
a) 2
0)
(/)
c
1.5
1
L i
Adjusted r2
0.24
J
F
23.95
:' I
r
dt
P
73
<0.01
« i
i
1.2 1.4 1.6 1.8 2 2.2 2.4
In Se diet mg/kg dw
B-15
-------
Table B-5. Gadwall Trophic Transfer Factor (TTF).
Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
4.1
1.75
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
5
2.13
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
6.6
2.82
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
4.4
1.88
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
6.2
2.65
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
7.4
3.16
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
4.6
1.96
Lambing et al. 1994
B-21
1.69
0.75
4.30
0.25
2.34
5.7
2.43
Lambing et al. 1994
B-21
1.85
0.75
4.30
0.25
2.46
2.8
1.14
Lambing et al. 1994
B-22
1.20
0.75
3.57
0.25
1.79
2.1
1.17
Lambing et al. 1994
B-22
1.20
0.75
3.57
0.25
1.79
8.9
4.96
Lambing et al. 1994
B-22
1.20
0.75
3.57
0.25
1.79
10
5.58
Lambing et al. 1994
B-22
1.20
0.75
3.57
0.25
1.79
2.2
1.23
Lambing et al. 1994
B-22
1.20
0.75
3.57
0.25
1.79
14
7.81
Lambing et al. 1994
B-22
5.60
0.75
3.57
0.25
5.09
2.7
0.53
Lambing et al. 1994
B-22
5.60
0.75
3.57
0.25
5.09
2.6
0.51
Lambing et al. 1994
B-22
5.60
0.75
3.57
0.25
5.09
4.2
0.82
Lambing et al. 1994
B-22
5.60
0.75
3.57
0.25
5.09
3.3
0.65
Lambing et al. 1994
B-23
1.80
0.75
3.79
0.25
2.30
3.3
1.44
Lambing et al. 1994
B-23
1.80
0.75
3.79
0.25
2.30
13
5.66
Lambing et al. 1994
B-23
1.80
0.75
3.79
0.25
2.30
8.1
3.52
Lambing et al. 1994
B-23
1.80
0.75
3.79
0.25
2.30
3.5
1.52
Lambing et al. 1994
B-23
1.80
0.75
3.79
0.25
2.30
3.7
1.61
B-16
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
B-23
1.80
0.75
3.79
0.25
2.30
B-23
1.80
0.75
3.79
0.25
2.30
B-23
1.80
0.75
3.79
0.25
2.30
B-26
0.66
0.75
3.23
0.25
1.30
B-26
0.77
0.75
4.20
0.25
1.63
B-26
0.77
0.75
4.20
0.25
1.63
B-26
1.36
0.75
4.20
0.25
2.07
B-26
1.36
0.75
4.20
0.25
2.07
B-26
1.36
0.75
4.20
0.25
2.07
B-26
1.36
0.75
4.20
0.25
2.07
B-26
1.36
0.75
4.20
0.25
2.07
B-26
1.36
0.75
4.20
0.25
2.07
B-26
1.36
0.75
4.20
0.25
2.07
B-26
1.10
0.75
4.20
0.25
B-26
1.10
0.75
4.20
0.25
B-26
1.10
0.75
4.20
0.25
B-26
1.10
0.75
4.20
0.25
B-26
1.10
0.75
4.20
0.25
Harney
0.51
0.75
1.55
0.25
0.77
Harney
0.51
0.75
1.55
0.25
0.77
Harney
0.51
0.75
1.55
0.25
0.77
N Malheur
0.56
0.75
2.20
0.25
0.97
B-17
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Rinella and Schuler
1992
N Malheur
0.56
0.75
2.20
0.25
0.97
1.4
1.44
Rinella and Schuler
1992
N Malheur
0.56
0.75
2.20
0.25
0.97
1.4
1.44
Rinella and Schuler
1992
N Malheur
0.56
0.75
2.20
0.25
0.97
1.5
1.55
Rinella and Schuler
1992
S Malheur
0.82
0.75
1.20
0.25
0.92
1.1
1.20
Rinella and Schuler
1992
S Malheur
0.82
0.75
1.20
0.25
0.92
1.3
1.42
Rinella and Schuler
1992
S Malheur
0.82
0.75
1.20
0.25
0.92
1.1
1.20
Median TTF
1.78
2.5
1
"O «
O) 1.5 i |
t 1 ' ¦ .
CD #
S1 I
$ 0.5
-0.5
-0.5 0 0.5 1
In Se diet mg/kg dw
Adjusted r2
0.66
F
86.17
df
42
P
<0.001
B-18
-------
Table B-6. Pied-Billed Grebe. Bird Egg to Fi
The TTF for this species was calculated using a
5h (TTF).
1 available paired egg-animal Se measurements
Study
Site
Fish Se (mg/kg)
Egg Se
(mg/kg)
TTF
Byron and Santolo 2010
BCW
61.30
36.78
0.60
Byron and Santolo 2010
UCI
5.4
9.55
1.77
Byron et al. 2012
BCW
49.74
40
0.80
Byron et al. 2012
UCI
12.82
6.06
0.47
Byron and Santolo 2014
BCW
52.49
43
0.82
Byron and Santolo 2014
UCI
5.7
4.35
0.76
Median TTF
Adjusted r2
0.78
0.81
22.25
Df
0.009
B-19
-------
Table B-7. Red-Winged Blackbird Trophic Transfer Factor (TTF).
Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1991
7
10.72
0.17
31.75
0.83
28.18
17.6
0.62
Butler etal. 1993
LP4
1.50
0.17
3.20
0.83
2.91
2.9
1.00
Butler etal. 1993
LP4
1.50
0.17
3.20
0.83
2.91
2.9
1.00
Butler etal. 1993
LP4
1.50
0.17
3.20
0.83
2.91
2.5
0.86
Butler etal. 1993
LP4
1.50
0.17
3.20
0.83
2.91
3.5
1.20
Butler etal. 1994
MKP
9.90
0.17
32.00
0.83
28.24
8.1
0.29
Butler etal. 1994
MKP
9.90
0.17
32.00
0.83
28.24
7.1
0.25
Butler etal. 1994
MKP
6.45
0.17
32.00
0.83
27.66
16
0.58
Butler etal. 1994
MKP
6.45
0.17
32.00
0.83
27.66
9.2
0.33
Butler etal. 1994
MKP
6.45
0.17
32.00
0.83
27.66
15
0.54
Butler etal. 1995
DD
0.83
0.17
0.83
0.83
0.83
1.6
1.93
Butler etal. 1991
10
2.55
0.17
4.80
0.83
4.42
8.1
1.83
Butler et al. 1991
10
2.55
0.17
4.80
0.83
4.42
8.6
1.95
Butler etal. 1997
CHP
3.75
0.17
12.00
0.83
10.60
7.7
0.73
Butler etal. 1997
CHP
3.75
0.17
12.00
0.83
10.60
5.8
0.55
Butler etal. 1997
CHP
3.75
0.17
12.00
0.83
10.60
9.9
0.93
Butler etal. 1997
CHP
3.75
0.17
12.00
0.83
10.60
7.1
0.67
Butler etal. 1997
DCP1
1.45
0.17
6.45
0.83
5.60
4.2
0.75
Butler etal. 1997
DCP1
1.45
0.17
6.45
0.83
5.60
5.3
0.95
Butler etal. 1997
DCP1
1.45
0.17
6.45
0.83
5.60
4.8
0.86
Butler etal. 1997
LCHP1
0.44
0.17
1.91
0.83
1.66
2.9
1.75
Butler etal. 1997
LCHP1
0.44
0.17
1.91
0.83
1.66
3
1.81
Butler etal. 1997
LCHP1
0.44
0.17
1.91
0.83
1.66
3
1.81
B-20
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler et al. 1997
WCP
2.30
0.17
9.70
0.83
8.44
2.1
0.25
Butler et al. 1997
WCP
2.30
0.17
9.70
0.83
8.44
2.8
0.33
Butler etal. 1997
WCP
2.30
0.17
9.70
0.83
8.44
3.1
0.37
Median TTF
0.86
3.5
3
I2"5
o>
1 2
O)
S? 1.5
(1)
CO
C 1
0.5
i
*
~ * ^~
~
. "" ~
~ ~
~
Adjusted r2
0.77
F
73.92
df
21
P
<0.001
-0.2 0.3 0.8 1.3 1.8 2.3 2.8 3.3 3.8
In Se diet mg/kg dw
B-21
-------
Table B-8. Yellow-Headed Blackbird Trophic Transfer Factor (TTF).
Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1991
7
10.72
0.25
31.75
0.75
26.50
8
0.30
Butler etal. 1991
7
10.72
0.25
31.75
0.75
26.50
11.5
0.43
Butler etal. 1994
MKP
9.90
0.25
32.00
0.75
26.48
12
0.45
Butler etal. 1994
MKP
6.45
0.25
32.00
0.75
25.61
9.9
0.39
Butler etal. 1994
MKP
6.45
0.25
32.00
0.75
25.61
10
0.39
Butler etal. 1994
MKP
6.45
0.25
32.00
0.75
25.61
15
0.59
Butler etal. 1994
MKP
6.45
0.25
32.00
0.75
25.61
17
0.66
Butler etal. 1997
MNP2
3.85
0.25
4.40
0.75
4.26
7
1.64
Butler etal. 1997
MNP2
3.85
0.25
4.40
0.75
4.26
5.2
1.22
Butler etal. 1997
MNP2
3.85
0.25
4.40
0.75
4.26
3.4
0.80
Butler etal. 1997
MNP2
3.85
0.25
4.40
0.75
4.26
5.9
1.38
Butler etal. 1993
LP4
1.50
0.25
3.20
0.75
2.78
3.9
1.41
Butler etal. 1993
LP4
1.50
0.25
3.20
0.75
2.78
3.5
1.26
Butler etal. 1993
R1
4.64
0.25
3.33
0.75
3.66
3.9
1.07
Butler etal. 1993
R1
4.64
0.25
3.33
0.75
3.66
5.3
1.45
Butler etal. 1993
R1
4.64
0.25
3.33
0.75
3.66
5.2
1.42
Butler etal. 1993
R1
4.64
0.25
3.33
0.75
3.66
3.7
1.01
Butler etal. 1995
XT
0.41
0.25
1.33
0.75
1.10
2.9
2.64
Butler et al. 1995
TT
0.41
0.25
1.33
0.75
1.10
4.8
4.38
B-22
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
Median TTF
Adjusted r2
df
B-23
-------
Calculation of TTFcomP°slte for Species with measured TTF
This section describes the calculation of TTFcomposite for the eight bird species with
measured TTF values using data listed in the preceding tables. TTFcomposite were calculated from
food webs modeled using information from the Cornell Lab of Ornithology Birds of the World
web site: (https://birdsoftheworld.org/bow/home), and following the methods described in Part
5.4.2.1. Calculations were made using different combinations of (Equation 5-2) and (Equation
5-3), shown below as Appendix Equations B-l and B-2, depending on the specific modeled food
web.
where:
'/"/J/IL2
'/"IJ/IL3
TTFTL4
]~"YpcomPos^te
yy'pcomposite _ yy^TM ^ yy^TLS ^ yy^rTL2
(Appendix Equation B-l)
= the trophic transfer factor of the trophic level 2 species
= the trophic transfer factor of the trophic level 3 species
= the trophic transfer factor of the trophic level 4 species
the product of all the trophic transfer factors
Similarly, the consumption of more than one species at the same trophic level can also be
modeled by expressing the TTF at a particular trophic level as the weighted average of the T'/T's
of all species consumed given as:
ttfTLx = ^JJTFJLx X Wi)
i
(Appendix Equation B-2)
where:
TTFjLx = the trophic transfer factor of the ith species at a particular trophic level
Wi = the proportion of the ith species consumed
Invertebrate, fish, and bird TTFs used in the food web model calculations are from Table
5-1, Table 5-2, and Table 5-3, respectively. TTFcomP"slte for these eight bird species are listed in
Table 5-5.
B-24
-------
Non-Migratory Species
American Coot
The diet of American coot is described as consisting of predominantly plant matter,
including pond weeds, sedges, algae, and wild and domestic grasses, as well as species such as
eelgrass, wild celery, duckweeds, cattail, watermilfoil, and numerous other plants. Animal matter
is relatively uncommon, but can be important during the breeding season, especially for growing
young. Important animal food items, from greatest to least importance, include insects, mollusks,
small crustaceans, and crawfish, as well as some small vertebrates, such as salamander larvae,
tadpoles, and small fish (Brisbin and Mowbray 2020). Based on this information, the American
coot diet was modeled as consisting of 80% aquatic plants, 8% insects, 6% mollusks, 4% small
crustaceans, and 2% crayfish.
The American coot species TTF value, based on a diet of 80% plants and 20% animals, is
1.89 (Table B-2). The invertebrate TTFs are as follows: 2.14 (insects), 4.29 (mollusks), 1.32
(small crustaceans - median amphipod and copepod), and 1.46 (crayfish), respectively (Table
5-1).The American coot TTFcomposite is 2.48 and is calculated as follows.
TTFcomposite = ^ 89 x g.g] + [i.gg x ((2.14 x 0.08) + (4.29 x 0.06) + (1.32 x 0.04) +
(1.46x0.02))] = 2.48
Red-Winged Blackbird
The red-winged blackbird diet during the breeding season is described as consisting
primarily of animal matter, although this can vary with date, sex, and access to agricultural
habitats (Yasukawa and Searcy 2020). For example, within agricultural habitats in Ontario,
stomach contents were 51% insects and 42% agricultural waste grain. Within marshes in
Manitoba, however, diet was 100% animal matter. Dietary animal matter consists almost entirely
of insects. Based on this information, the red-winged blackbird diet was modeled as consisting of
17%) aquatic plants and 83% aquatic insects.
The red-winged blackbird species TTF value, based on a diet of 17% aquatic plants and
83%) aquatic insects, is 0.86 (Table B-7). The aquatic insect TTF, calculated as the median of all
insect orders, is 2.14 (Table 5-1). The red-winged blackbird TTFcomposite is 1.67 and is calculated
as follows.
B-25
-------
TTFcomposite = [g 86 x Q.17] + [0.86 X 2.14 X 0.83] = 1.67
Migratory Species
The EPA conducted an analysis to compare breeding season data (defined here as April
through July) vs. all available data for the migratory species. Because many of the bird species
analyzed eat invertebrates, and invertebrate sampling collections are typically conducted outside
of the breeding season time frames, many of the data for the breeding season only did not
produce a statistically significant regression. For those birds where enough data were available
during the breeding season to produce statistically significant results, the resulting TTFs were
similar to the all-data scenarios of the same bird species. For these reasons, the EPA decided to
derive all of the migratory TTFs using all data available in each study.
American avocet
American avocets are generalist tactile feeders, and their diet varies by habitat
(Ackerman et al. 2020). Stomach content results from six inland studies across Western North
America reveal that avocets consume a range of plant and animal species. Plant matter, primarily
seeds, range from 1-35%. Animal matter consists primarily of dipterans, predominantly
chironomids, followed by corixidae, beetles, mayflies, annelids, gastropods, crustaceans, other
invertebrates, and very rarely small fish and amphibians. Based on this information, the
American avocet diet was modeled as consisting of 13% plants, 55% chironomids, 10% corixids,
1% mayflies, 10% other insects (mainly beetles), 3% annelids, 3% mollusks, 2% crustaceans,
and 3% other invertebrates. The TTFcomposite is calculated as follows.
The American avocet species TTF value, based on a diet of 13% plants and 87% animals,
is 1.44 (Table B-l). The invertebrate TTFs are as follows: 1.90 (Chironomidae), 1.48
(Corixidae), 4.29 (mollusks), 2.38 (mayflies), 2.14 (insects), 1.29 (annelids), 1.41 (crustaceans),
and 1.89 (all invertebrates), respectively (Table 5-1). The American avocet TTFcomposite is 2.61
and is calculated as follows.
B-26
-------
TTFcomposite = ^ 44 x 0 13] + ^144 x ^ 90 x 0.55) + (1.48 X 0.10) + ( 2.38 X 0.01) +
(2.14 X 0.10) + (1.29 X 0.03) + (4.29 X 0.03) + (1.41 X 0.02) + (1.89 X 0.03))] =
2.61
Cinnamon Teal
The diet of cinnamon teal varies with location and season. The average diets according to
percent dry weight of esophageal contents from six studies from the Western United States
during the spring and summer were approximately 36% dipterans (primarily chironomids), 9.5%
gastropods, 4% corixidae, 3.5% cladocerans, 2% beetles, 1% odonates, 2% other invertebrates,
and 42% plant matter, primarily seeds (Gammonley 2020). Based on this information, the
cinnamon teal diet was modeled as consisting of 42% aquatic plants, 36% chironomids, 9.5%
mollusks (gastropods), 4% corixidae, 3.5% cladocerans, 2% other insects (beetles), 1% odonates,
and 2% other invertebrates.
The cinnamon teal species TTF value, based on a diet of 42% plants and 58% animals, is
1.79 (Table B-3). The TTFcomposite is calculated using the following invertebrate TTFs: 1.90
(Chironomidae), 4.29 (mollusks), 1.48 (Corixidae), 0.74 (Cladocera), 2.14 (insects), 2.425
(Odonata), and 1.89 (all invertebrates), respectively (Table 5-1). The cinnamon teal TTFcomposite is
3.04 and is calculated as follows.
TTFcomposite = ^ 79 x 0.42] + [l.79 x ((1.90 x 0.36) + (4.29 x 0.095) + (1.48 x 0.04) +
(0.74 x 0.035) + (2.14 x 0.02) + (2.425 x 0.01) + (1.89 x 0.02))] =
3.04
Eared Grebe
The diet of eared grebes consists of animals, principally invertebrates but also
occasionally small fish (Cullen et al. 2020). In saline lakes, their diet consists predominantly of
brine shrimp (60-93%) and brine flies (5-40%) depending on their relative availability. Eared
grebes have also been found to feed on pile worms, amphipods and small fish. In breeding
grounds and in migration in Western States, eared grebes feed primarily on insects, particularly
on water boatmen, as well as diving beetles, caddisflies, mayflies, chironomids, and odonates.
Based on this information, the eared grebe diet was modeled as consisting of 45% crustaceans
B-27
-------
(brine shrimp), 25% dipterans (brine flies and chironomids), 20% corixidae, 5% other insects,
and 5% annelids.
The eared grebe species TTF value, based on a 100% animal diet, is 2.00 (Table B-4).
The invertebrate TTFs are as follows: 1.41 (crustaceans), 1.90 (Diptera), 1.48 (Corixidae), 2.14
(insects), and 1.29 (annelids), respectively (Table 5-1). The TTFcomposite for eared grebe is 3.15
and is calculated as follows.
TTFcomposite = [2.00 x ((1.41 x 0.45) + (1.90 x 0.25) + (1.48 x 0.2) + (2.14 x 0.05) +
(1.29 x 0.05))] = 3.15
Gadwall
The diet of gadwall varies seasonally, with a diet consisting almost entirely of plant
matter in the fall and winter, and between 23-46% animal and 42-54% plant matter during the
summer (Leschack et al. 2020). Plants eaten include filamentous algae, water milfoil, widgeon
grass, duckweed, and pondweed, depending on availability. Animal food items consist of midge
larvae, aphids, snails, and beetle larvae (Leschack et al. 2020). Based on this information, the
gadwall diet was modeled as consisting of 75% plants, 11% chironomids, 7% insects (beetles),
5% small crustaceans, and 2% snails.
The gadwall species TTF value, based on a diet of 75% plants and 25% animals, is 1.78
(Table B-5). The invertebrate TTFs are as follows: 1.90 (chironomids), 2.14 (insects - beetles),
1.32 (small crustaceans - median amphipod and copepod), and 4.29 (mollusks), respectively
(Table 5-1). The TTFcomposite for gadwall is 2.24 and is calculated as follows.
TTFcomposite _ ^jq x qjS]
+ [1.78 x ((1.90 x 0.11) + (2.14 x 0.07) + (1.32 x 0.05) + (4.29 x 0.02))]
= 2.24
Pied-Billed Grebe
The diet of pied-billed grebes includes decapod crustaceans, especially crayfish, aquatic
insects, and fishes. In some areas, prey items also include leeches, gizzard shad, or frogs and
tadpoles. Pied-billed grebes in the Ashless wetlands of Manitoba kill and eat tiger salamanders.
Stomach contents of 174 individuals from the Eastern United States contained 376 food items:
B-28
-------
62 decapods (crayfish, crabs, shrimps, etc.), 13 dragonfly larvae, 77 bugs, 124 beetles, 76 fishes,
5 mollusks, and 19 other invertebrates (Muller and Storer 2020). Based on the dietary
information, and after applying a general weighting factor of 5 to fish and crayfish to account for
their larger size, the pied-billed grebe diet was modeled as 33% crayfish, 13% beetles, 8%
corixids, 2% other invertebrates, 1% mollusks, 1% dragonflies, and 42% fish.
Data on T'/T's for piscivorous bird species are limited, and the pied-billed grebe was the
only predominantly piscivorous species with sufficient data to calculate a TTF following the
approach used in the 2016 aquatic life criteria document (U.S. EPA 2016a). The pied-billed
grebe species TTF value, based on available bird egg-fish paired data reported in Byron and
Santolo (2010, 2014); Byron et al. (2012) for two sites in the Newport Bay, CA watershed, is
0.78 (Table B-6). Limited paired data exist for two additional species that are largely
piscivorous, but insufficient data were available for regression analysis. King et al. (2003)
measured selenium in double-crested cormorant eggs during 1999-2000 and in three fish species
(largemouth bass, red shiner, threadfin shad) during 2000 from Topock Marsh, Arizona. The
double-crested cormorant TTF was calculated as 0.84. Martinez (1994) measured selenium in
green heron eggs and egg masses (consisting of the ovary and the cluster of developing eggs
surrounding the ovary) from two lakes in the lower Colorado River in southwest Arizona during
the breeding season of 1993. Lusk (1993) measured selenium in fish and invertebrate prey
species from the same two sites in 1991 and 1992. Based on these data, the green heron TTF was
1.35 based on diet paired with egg and 2.37 based on diet paired with egg masses. Because the
similarity of the pied-billed grebe TTF to the TTF of the piscivorous double-crested cormorant,
and because it is the only species for which a TTF could be calculated from paired data, the pied-
billed grebe TTF was considered to be an acceptable TTF, and an acceptable surrogate TTF for
piscivorous birds.
The invertebrate portion of their diet was modeled using T'/T's of 1.46 (crayfish), 2.14
(insects - beetles), 1.48 (Corixidae), 1.89 (all invertebrates), 4.29 (mollusks), and 1.97
(dragonflies) from Table 5-1. The piscivorous portion of their diet was modeled using fish
Yjpcomposite va|ues for representative fish taxa from Table B-14. For modeling purposes, it was
assumed the pied billed grebe consumed equal proportions of carp and minnow species, catfish,
sticklebacks, sunfish (Lepomis sp.), sculpin, and killifish (Muller and Storer 2020), with
B-29
-------
corresponding jjfcomP°site 0f 1.58 (Cypriniformes), 1.54 (Siluriformes), 2.47
(Gasterosteiformes), 2.15 (Lepomis), 2.69 (Cottus), and 2.44 (.Fundulus).
The TTFcomposite for pied billed grebe is 1.47 and is calculated as follows.
TTFcomposite = |qjq x ((146 x q.33) + (2.14 X 0.13) + (1.48 X 0.08) + (1.89 X 0.02) +
(4.29 x 0.01) + (1.97 x 0.01))] + [0.78 x ((1.58 x 0.07) + (1.54 x 0.07) + (2.47 x
0.07) + (2.15 X 0.07) + (2.69 X 0.07) + (2.44 X 0.07))] = 1.47
Yellow-Headed Blackbird
The diet of yellow-headed blackbird consists of a variety of insects and seeds. In a study
of 15 birds in Utah, the diet consisted of seven orthoptera, seven odonata, 96 coleoptera, 40
lepidoptera, 13 diptera, 10 hymenoptera, and 109 seeds (Twedt and Crawford 2020). Based on
the dietary information listed above, the yellow-headed blackbird diet was modeled as consisting
of 25% plants and 75% insects.
The yellow-headed blackbird species TTF value, based on a diet of 25% plants and 75%
animals, is 1.04 (Table B-8). The aquatic insect TTF, calculated as the median of all insect
orders, is 2.14 (Table 5-1). The TTFcomposite for yellow-headed blackbird is 1.93 and is calculated
as follows.
TTFcomposite = ^ 04 x q.25] + [1.04 x 2.14 x 0.75] = 1.93
Summary
Composite TTFs could be calculated from species-specific measured data for two non-
migratory species: American coot and red-winged blackbird, and six migratory species:
American avocet, cinnamon teal, eared grebe, gadwall, pied-billed grebe, and yellow-headed
blackbird. Available dietary information describes the pied-billed grebe diet as a 100% animal
diet consisting of fish and invertebrates; however, the TTF for pied-billed grebe was calculated
from available paired data, which included only bird egg-fish selenium data. Species level TTFs
for these species are listed in Table 5-3, and composite TTFs for these species are listed in Table
5-5.
B-30
-------
Paired Surrogate Data Used to Calculate Bird Trophic Transfer Factors (TIF) for Threatened and
Endangered (T&E) Species
Composite TTFs were also calculated for 8 additional T&E bird species that did not have
species specific empirical bird TTF values: American dipper, brown pelican, bald eagle,
Ridgway's rail, light-footed Ridgway's rail, Yuma Ridgway's rail, black rail, and least tern.
Surrogate species were selected from the group of eight bird species with sufficient data to
calculate species level TTF values, based on similarity in dietary composition and if possible
taxonomic relatedness (within same order) to account for similarities in dietary composition and
physiology/life history, all of which may influence the accumulation of selenium.
After determining an appropriate surrogate species, the surrogate species-level TTF value
was calculated following the same methodology as previously described for species with
measured TTFs. Food web data were used to first determine the proportion of plants and animals
in a bird's diet, and then measured data from an appropriate surrogate species were weighted
accordingly to calculate a final surrogate species-level TTF. Table B-9 through Table B-13 list
paired data from the applicable surrogate bird species, as well as species-level TTF values
following dietary reweighting for the respective T&E bird species. The original pied-billed grebe
TTF was used as a surrogate for the T&E bird species whose were largely or entirely
piscivorous, because available paired data for pied-billed grebe only included bird egg and fish
selenium data. Methods and data requirements for the calculation of species level TTFs for re-
weighted diets were the same as previously described for species with empirically measured
TTFs. Finally, species level TTFs for T&E species were incorporated into the food web models
described below, following methods described in Part 5.4.2.1, which were used to calculate the
composite TTFs for T&E species listed in Table 5-6.
B-31
-------
Table B-9. Ridgway's Rail Trophic Transfer Factor (TTF) after Reweighting Surrogate Species American Coot Diet to a 15%
Plant and 85% Animal Diet.
Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1991
7
10.72
0.15
31.75
0.85
28.60
11.10
0.39
Butler etal. 1995
XT
0.41
0.15
1.33
0.85
1.19
1.10
0.93
Butler etal. 1995
XT
0.41
0.15
1.33
0.85
1.19
2.40
2.02
Butler etal. 1997
DCP1
1.45
0.15
6.45
0.85
5.70
8.20
1.44
Butler et al. 1997
DCP1
1.45
0.15
6.45
0.85
5.70
18.00
3.16
Butler etal. 1997
DCP1
1.45
0.15
6.45
0.85
5.70
8.60
1.51
Butler etal. 1997
DCP1
1.45
0.15
6.45
0.85
5.70
9.70
1.70
Butler etal. 1997
DCP1
1.45
0.15
6.45
0.85
5.70
8.70
1.53
Butler etal. 1997
MNP2
3.85
0.15
4.40
0.85
4.32
8.10
1.88
Butler etal. 1997
MNP2
3.85
0.15
4.40
0.85
4.32
3.60
0.83
Butler etal. 1997
MNP2
3.85
0.15
4.40
0.85
4.32
6.90
1.60
Butler etal. 1997
MNP2
3.85
0.15
4.40
0.85
4.32
8.40
1.95
Butler etal. 1997
MNP2
3.85
0.15
4.40
0.85
4.32
7.50
1.74
Butler etal. 1997
MNP2
3.85
0.15
4.40
0.85
4.32
8.40
1.95
Lambing 1988
7
0.47
0.15
6.50
0.85
5.60
1.40
0.25
Lambing 1988
7
0.47
0.15
6.50
0.85
5.60
1.60
0.29
Lambing 1988
7
0.47
0.15
6.50
0.85
5.60
1.10
0.20
Lambing et al. 1994
B-21
1.42
0.15
4.38
0.85
3.94
5.90
1.50
Lambing et al. 1994
B-21
1.42
0.15
4.38
0.85
3.94
2.60
0.66
Lambing et al. 1994
B-21
1.42
0.15
4.38
0.85
3.94
5.00
1.27
B-32
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-22
B-22
B-22
B-22
B-22
B-26
B-26
B-26
B-26
B-26
B-26
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.00
1.00
1.00
1.00
1.00
0.77
0.77
0.77
0.77
0.77
0.77
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
3.15
3.15
3.15
3.15
3.15
4.20
4.20
4.20
4.20
4.20
4.20
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
3.94
3.94
3.94
3.94
3.94
3.94
3.94
3.94
3.94
3.94
3.94
3.94
2.83
2.83
2.83
2.83
2.83
3.69
3.69
3.69
3.69
3.69
3.69
B-33
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
2.20
0.60
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
2.60
0.71
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
2.60
0.71
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
2.80
0.76
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
2.60
0.71
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
2.60
0.71
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
2.10
0.57
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
3.00
0.81
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
1.80
0.49
Lambing et al. 1994
B-26
0.77
0.15
4.20
0.85
3.69
1.80
0.49
Peterson et al. 1991
3
4.64
0.15
9.62
0.85
8.87
10.30
1.16
Peterson et al. 1991
3
4.64
0.15
9.62
0.85
8.87
13.10
1.48
Rinella and Schuler
1992
N Malheur
0.56
0.15
2.20
0.85
1.95
1.80
0.92
Rinella and Schuler
1992
N Malheur
0.56
0.15
2.20
0.85
1.95
1.50
0.77
Rinella and Schuler
1992
N Malheur
0.56
0.15
2.20
0.85
1.95
1.40
0.72
Rinella and Schuler
1992
N Malheur
0.56
0.15
2.20
0.85
1.95
1.50
0.77
Rinella and Schuler
1992
S Malheur
0.82
0.15
1.20
0.85
1.14
1.30
1.14
Rinella and Schuler
1992
S Malheur
0.82
0.15
1.20
0.85
1.14
1.00
0.87
Rinella and Schuler
1992
S Malheur
0.82
0.15
1.20
0.85
1.14
1.80
1.57
B-34
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Rinella and Schuler
1992
S Malheur
0.82
0.15
1.20
0.85
1.14
1.80
1.57
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.15
1.13
0.85
1.07
1.80
1.68
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.15
1.13
0.85
1.07
1.73
1.61
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.15
1.13
0.85
1.07
1.85
1.72
3
2.5
S
2
U)
1
I 1-5
o>
a)
if) 1
c
0.5
0
~
~ ~
! * /
~
~ I
* u
H . J
<- * * #
~
0.5 1 1.5 2 2.5 3 3.5
In Se diet mg/kg dw
Median TTF
0.96
Adjusted r2
0.53
F
69.67
df
61
P
<0.001
B-35
-------
Table B-10. Black Rail Trophic Transfer Factor (TTF) after Reweighting Surrogate Species American Coot Diet to a 13%
Plant and 87% Animal Diet.
Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1991
7
10.72
0.13
31.75
0.87
29.02
11.10
0.38
Butler etal. 1995
XT
0.41
0.13
1.33
0.87
1.21
1.10
0.91
Butler etal. 1995
XT
0.41
0.13
1.33
0.87
1.21
2.40
1.99
Butler etal. 1997
DCP1
1.45
0.13
6.45
0.87
5.80
8.20
1.41
Butler et al. 1997
DCP1
1.45
0.13
6.45
0.87
5.80
18.00
3.10
Butler etal. 1997
DCP1
1.45
0.13
6.45
0.87
5.80
8.60
1.48
Butler etal. 1997
DCP1
1.45
0.13
6.45
0.87
5.80
9.70
1.67
Butler etal. 1997
DCP1
1.45
0.13
6.45
0.87
5.80
8.70
1.50
Butler etal. 1997
MNP2
3.85
0.13
4.40
0.87
4.33
8.10
1.87
Butler etal. 1997
MNP2
3.85
0.13
4.40
0.87
4.33
3.60
0.83
Butler etal. 1997
MNP2
3.85
0.13
4.40
0.87
4.33
6.90
1.59
Butler etal. 1997
MNP2
3.85
0.13
4.40
0.87
4.33
8.40
1.94
Butler etal. 1997
MNP2
3.85
0.13
4.40
0.87
4.33
7.50
1.73
Butler etal. 1997
MNP2
3.85
0.13
4.40
0.87
4.33
8.40
1.94
Lambing 1988
7
0.47
0.13
6.50
0.87
5.72
1.40
0.24
Lambing 1988
7
0.47
0.13
6.50
0.87
5.72
1.60
0.28
Lambing 1988
7
0.47
0.13
6.50
0.87
5.72
1.10
0.19
Lambing et al. 1994
B-21
1.42
0.13
4.38
0.87
4.00
5.90
1.48
Lambing et al. 1994
B-21
1.42
0.13
4.38
0.87
4.00
2.60
0.65
Lambing et al. 1994
B-21
1.42
0.13
4.38
0.87
4.00
5.00
1.25
Lambing et al. 1994
B-21
1.42
0.13
4.38
0.87
4.00
3.80
0.95
Lambing et al. 1994
B-21
1.42
0.13
4.38
0.87
4.00
5.20
1.30
B-36
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-22
B-22
B-22
B-22
B-22
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
B-26
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.42
1.00
1.00
1.00
1.00
1.00
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.77
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
3.15
3.15
3.15
3.15
3.15
4.20
4.20
4.20
4.20
4.20
4.20
4.20
4.20
4.20
4.20
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
0.87
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
2.87
2.87
2.87
2.87
2.87
3.75
3.75
3.75
3.75
3.75
3.75
3.75
3.75
3.75
3.75
B-37
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Lambing et al. 1994
B-26
0.77
0.13
4.20
0.87
3.75
2.60
0.69
Lambing et al. 1994
B-26
0.77
0.13
4.20
0.87
3.75
2.60
0.69
Lambing et al. 1994
B-26
0.77
0.13
4.20
0.87
3.75
2.10
0.56
Lambing et al. 1994
B-26
0.77
0.13
4.20
0.87
3.75
3.00
0.80
Lambing et al. 1994
B-26
0.77
0.13
4.20
0.87
3.75
1.80
0.48
Lambing et al. 1994
B-26
0.77
0.13
4.20
0.87
3.75
1.80
0.48
Peterson et al. 1991
3
4.64
0.13
9.62
0.87
8.97
10.30
1.15
Peterson et al. 1991
3
4.64
0.13
9.62
0.87
8.97
13.10
1.46
Rinella and Schuler
1992
N Malheur
0.56
0.13
2.20
0.87
1.99
1.80
0.91
Rinella and Schuler
1992
N Malheur
0.56
0.13
2.20
0.87
1.99
1.50
0.75
Rinella and Schuler
1992
N Malheur
0.56
0.13
2.20
0.87
1.99
1.40
0.70
Rinella and Schuler
1992
N Malheur
0.56
0.13
2.20
0.87
1.99
1.50
0.75
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.30
1.13
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.00
0.87
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.80
1.56
Rinella and Schuler
1992
S Malheur
0.82
0.13
1.20
0.87
1.15
1.80
1.56
Rinella etal. 1994
Ft. Boise
WMA
0.78
0.13
1.13
0.87
1.08
1.80
1.67
B-38
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Rinellaetal. 1994
Ft. Boise
WMA
0.78
0.13
1.13
0.87
1.08
1.73
1.60
Rinellaetal. 1994
Ft. Boise
WMA
0.78
0.13
1.13
0.87
1.08
1.85
1.71
3
2.5
§
« 2
5, 1-5
O)
0)
Q*
CO 1
c
0.5
0
~
.
! #
~ ' '
. ! r
. *
~
0.5 1 1.5 2 2.5 3 3.5
In Se diet mg/kg dw
Median TTF
0.95
Adjusted r2
0.52
F
68.24
df
61
P
<0.001
B-39
-------
Table B-ll. Light-Footed Ridgeway's Rail and Yuma Rail Trophic Transfer Factor (TTF) after Reweighting Surrogate
Species American Coot Diet to a 100% Animal Diet.
Because these species eat a 100% animal diet, all paired animal-egg measurements were used, regardless of whether a paired plant
measurement was available. Rows with data pairs that were removed during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1991
7
n/a
0.0
31.75
1.0
31.75
11.1
0.35
Butler etal. 1995
XT
n/a
0.0
1.33
1.0
1.33
1.1
0.83
Butler etal. 1995
XT
n/a
0.0
1.33
1.0
1.33
2.4
1.81
Butler etal. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
8.2
1.27
Butler etal. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
18
2.79
Butler etal. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
8.6
1.33
Butler etal. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
9.7
1.50
Butler etal. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
8.7
1.35
Butler etal. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
8.1
1.84
Butler etal. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
3.6
0.82
Butler etal. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
6.9
1.57
Butler etal. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
8.4
1.91
Butler etal. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
7.5
1.70
Butler etal. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
8.4
1.91
Lambing 1988
7
n/a
0.0
6.50
1.0
6.50
1.4
0.22
Lambing 1988
7
n/a
0.0
6.50
1.0
6.50
1.6
0.25
Lambing 1988
7
n/a
0.0
6.50
1.0
6.50
1.1
0.17
Lambing 1988
10
n/a
0.0
1.10
1.0
1.10
1.6
1.45
Lambing 1988
10
n/a
0.0
1.10
1.0
1.10
1.4
1.27
Lambing 1988
10
n/a
0.0
1.10
1.0
1.10
1.3
1.18
B-40
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
B-16
B-16
B-16
B-16
B-16
B-19
B-19
B-19
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-21
B-22
Plant Se
(mg/kg)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Plant
Diet
Prop.
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Invert. Se
(mg/kg)
4.80
4.80
4.80
4.80
4.80
5.60
5.60
5.60
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
3.15
Invert
Diet
Prop.
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Diet Se
(mg/kg)
4.80
4.80
4.80
4.80
4.80
5.60
5.60
5.60
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
4.38
3.15
B-41
-------
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
1994
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
B-22
n/a
0.0
3.15
1.0
3.15
B-22
n/a
0.0
3.15
1.0
3.15
B-22
n/a
0.0
3.15
1.0
3.15
B-22
n/a
0.0
3.15
1.0
3.15
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
B-26
n/a
0.0
4.20
1.0
4.20
Spring Creek
Spring Creek
n/a
n/a
0.0
0.0
1.60
1.60
1.0
1.0
1.60
1.60
B-42
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Ong et al. 1991
24C
n/a
0.0
1.20
1.0
1.20
0.72
0.60
Ong et al. 1991
24C
n/a
0.0
1.20
1.0
1.20
0.75
0.63
Ong et al. 1991
24C
n/a
0.0
1.20
1.0
1.20
0.76
0.63
Ong et al. 1991
24C
n/a
0.0
1.20
1.0
1.20
0.76
0.63
Peterson et al. 1991
3
n/a
0.0
9.62
1.0
9.62
10.3
1.07
Peterson et al. 1991
3
n/a
0.0
9.62
1.0
9.62
13.1
1.36
Rinella and Schuler
1992
N Malheur
n/a
0.0
2.20
1.0
2.20
1.8
0.82
Rinella and Schuler
1992
N Malheur
n/a
0.0
2.20
1.0
2.20
1.5
0.68
Rinella and Schuler
1992
N Malheur
n/a
0.0
2.20
1.0
2.20
1.4
0.64
Rinella and Schuler
1992
N Malheur
n/a
0.0
2.20
1.0
2.20
1.5
0.68
Rinella and Schuler
1992
S Malheur
n/a
0.0
1.20
1.0
1.20
1.3
1.08
Rinella and Schuler
1992
S Malheur
n/a
0.0
1.20
1.0
1.20
1
0.83
Rinella and Schuler
1992
S Malheur
n/a
0.0
1.20
1.0
1.20
1.8
1.50
Rinella and Schuler
1992
S Malheur
n/a
0.0
1.20
1.0
1.20
1.8
1.50
Rinella etal. 1994
Ft. Boise
WMA
n/a
0.0
1.13
1.0
1.13
1.8
1.60
Rinella etal. 1994
Ft. Boise
WMA
n/a
0.0
1.13
1.0
1.13
1.73
1.54
B-43
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
Rinellaetal. 1994
Ft. Boise
WMA
n/a
0.0
1.13
1.0
1.13
1.85
Median TTF
Adjusted r2
df
B-44
-------
Table B-12. American Dipper. Bird Egg to Diet (TTF) after Reweighting Surrogate Species Red-Winged Blackbird to a 100%
Animal Diet.
Because this species eats a 100% animal diet, all paired animal-egg measurements were used. Rows with data pairs that were removed
during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1991
7
n/a
0.0
31.75
1.0
31.75
17.6
0.55
Butler et al. 1993
LP4
n/a
0.0
3.20
1.0
3.20
2.9
0.91
Butler et al. 1993
LP4
n/a
0.0
3.20
1.0
3.20
2.9
0.91
Butler et al. 1993
LP4
n/a
0.0
3.20
1.0
3.20
2.5
0.78
Butler et al. 1993
LP4
n/a
0.0
3.20
1.0
3.20
3.5
1.09
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
8.1
0.25
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
7.1
0.22
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
16
0.50
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
9.2
0.29
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
15
0.47
Butler et al. 1995
DD
n/a
0.0
0.83
1.0
0.83
1.6
1.94
Butler etal. 1991
10
n/a
0.0
4.80
1.0
4.80
8.1
1.69
Butler et al. 1991
10
n/a
0.0
4.80
1.0
4.80
8.6
1.79
Butler et al. 1997
CHP
n/a
0.0
12.00
1.0
12.00
1.1
0.64
Butler et al. 1997
CHP
n/a
0.0
12.00
1.0
12.00
5.8
0.48
Butler et al. 1997
CHP
n/a
0.0
12.00
1.0
12.00
9.9
0.83
Butler et al. 1997
CHP
n/a
0.0
12.00
1.0
12.00
7.1
0.59
Butler et al. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
4.2
0.65
Butler et al. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
5.3
0.82
Butler et al. 1997
DCP1
n/a
0.0
6.45
1.0
6.45
4.8
0.74
B-45
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler et al. 1997
LCHP1
n/a
0.0
1.91
1.0
1.91
2.9
1.52
Butler et al. 1997
LCHP1
n/a
0.0
1.91
1.0
1.91
3
1.57
Butler et al. 1997
LCHP1
n/a
0.0
1.91
1.0
1.91
3
1.57
Butler et al. 1997
WCP
n/a
0.0
9.70
1.0
9.70
2.1
0.22
Butler et al 1997
WCP
n/a
0.0
9.70
1.0
9.70
2.8
0.29
Butler et al. 1997
WCP
n/a
0.0
9.70
1.0
9.70
3.1
0.32
Median TTF
0.74
3.5
3
I2-5
O)
1 2
cn
ST 15
ID
w
C 1
0.5
\
*
~ ~ ~
~
Adjusted r2
0.77
F
74.15
df
21
P
<0.001
-0.2 0.3 0.8 1.3 1.8 2.3 2.8 3.3 3.8
In Se diet mg/kg dw
B-46
-------
Table B-13. American Dipper. Bird Egg to Diet (TTF) after Reweighting Surrogate Species Yellow-Headed Blackbird to a
100% Animal Diet.
Because this species eats a 100% animal diet, all paired animal-egg measurements were used. Rows with data pairs that were removed
during outlier analysis are identified with bold and italics.
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
TTF
Butler etal. 1991
7
n/a
0.0
31.75
1.0
31.75
8
0.25
Butler etal. 1991
7
n/a
0.0
31.75
1.0
31.75
11.5
0.36
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
12
0.38
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
9.9
0.31
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
10
0.31
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
15
0.47
Butler et al. 1994
MKP
n/a
0.0
32.00
1.0
32.00
17
0.53
Butler et al. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
7
1.59
Butler et al. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
5.2
1.18
Butler et al. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
3.4
0.77
Butler et al. 1997
MNP2
n/a
0.0
4.40
1.0
4.40
5.9
1.34
Butler et al. 1993
LP4
n/a
0.0
3.20
1.0
3.20
3.9
1.22
Butler et al. 1993
LP4
n/a
0.0
3.20
1.0
3.20
3.5
1.09
Butler et al. 1993
R1
n/a
0.0
3.33
1.0
3.33
3.9
1.17
Butler et al. 1993
R1
n/a
0.0
3.33
1.0
3.33
5.3
1.59
Butler et al. 1993
R1
n/a
0.0
3.33
1.0
3.33
5.2
1.56
Butler et al. 1993
R1
n/a
0.0
3.33
1.0
3.33
3.7
1.11
Butler et al. 1995
TT
n/a
0.0
1.33
1.0
1.33
2.9
2.19
Butler et al. 1995
TT
n/a
0.0
1.33
1.0
1.33
4.8
3.62
B-47
-------
Study
Site
Plant Se
(mg/kg)
Plant
Diet
Prop.
Invert. Se
(mg/kg)
Invert
Diet
Prop.
Diet Se
(mg/kg)
Egg Se
(mg/kg)
Median TTF
Adjusted r2
df
B-48
-------
Calculation of jjfcomP°s'te for t&E Species
This section describes the calculation of TTFcomposite values for the eight T&E bird species
with measured TTF of surrogate species using data listed in the preceding tables. TTFcomposite
value were calculated from food webs modeled using information from the Cornell Lab of
Ornithology Birds of the World web site: (https://birdsoftheworld.org/bow/home), and other
published data sources following the methods described in Part 5.4.2.1. TTFcomposite values for
these species are listed in Table 5-6.
Composite TTF Results
American Dipper
American dippers consume a wide range of aquatic insects, primarily benthic
macroinvertebrate larvae such as mayflies (Ephemeroptera), caddisflies (Trichoptera), stoneflies
(Plecoptera), and Dipterans (Kingery and Wilson 2020; U.S. FWS 2017). This species will also
consume other aquatic organisms, including small fish and fish eggs. The abundance of prey
items determines the presence of dippers within a watershed (Feck 2002). The diet of American
dippers varies based time of the year (i.e., breeding season or non-breeding season) and habitat
(Kingery and Wilson 2020). Morrissey et al. (2010, 2012) found that female American dippers
switched to feeding at a higher trophic level (such as fish and predatory invertebrates) during
egg-laying. Additionally, using isotopic signatures, Morrissey et al. (2004) determined that non-
migratory dippers ate a higher percentage of fish (42% ± 7) than migrant dippers (22% ± 6).
American dippers tend to consume smaller fish, and fish eggs, primarily salmonid species and
sculpins (Kingery and Wilson 2020). Based on this information, the American dipper diet was
modeled under two scenarios: a low fish diet (diet consisting of 22% small fish and 78% aquatic
insect) and a high fish diet (diet consisting of 42% small fish and 58% aquatic insect). The
piscivorous portion of their diet was modeled as 75% salmonids and 25% sculpins.
An empirical TTFs was not available for American dipper, so the TTF for this species of
concern was calculated from closely related surrogate species with empirical bird TTFs. The
American dipper TTF value, calculated as the average of the two species (red-winged blackbird
and yellow-headed blackbird) from the same order (Passeriformes) based on a 100% animal diet,
was 0.92 (Table B-12 and Table B-13). The aquatic insect TTF, calculated as the median of all
insect orders, is 2.14 (Table 5-1). The fish TTFcomposite values are 2.33 (Salmonidae) and 2.69
B-49
-------
(Coitus) (Table B-14). The TTFcomposite for American dipper is 2.03 for the low fish (22%)
scenario and 2.08 for the high fish (42%) scenario, and they are calculated as follows.
Low fish diet scenario:
TTFcomposite = [ og2 x (2.14 x 0.78)] + [0.92 x ((2.33 x 0.165) + (2.69 x 0.055))]
= 2.03
High fish diet scenario:
TTFcomposite = [ Q92 x 214 x 0.58] + [0.92 x ((2.33 x 0.315) + (2.69 x 0.105))] = 2.08
Brown Pelican
Along the California coast, brown pelicans are dependent on small, surface schooling
fish, such as anchovy (Engraulis mordax) and Pacific sardines (Sardinops sagax). For example,
in the Salton Sea, the Brown pelican diet has been reported to consist of 90% northern anchovy
during the breeding season (U.S. FWS 2017). Based on this information, the dietary composition
of brown pelicans in California was modeled as 75% northern anchovy and 25% Pacific
sardines, based on the assumption that northern anchovies comprise a larger proportion of their
diet than Pacific sardines, but slightly less across the state than observed in the Salton Sea.
An empirical bird TTF was not available for brown pelican, so the species level TTF of
0.78 based on the piscivorous pied billed grebe was used (Table B-6). Composite TTFs for the
fish species in the brown pelican diet are not included in (Table B-14), so TTFcomposite values
were calculated for these species using dietary information from FishBase. The class-level
(Actinopterygii) TTF of 1.21 was used in all of the modeled fish TTFcomposite calculations because
no species level fish TTF values were available (Table 5-2).
Northern anchovy (https://www.fishbase.se/summary/Engraulis-mordax.htmn. and
Pacific sardines
(https://www.fishbase.se/summarv/SpeciesSummarv.php?ID=1477&AT=Pacific+sardine)
primarily consume zooplankton, so their diets were modeled as consisting of 100% zooplankton.
The TTFcomposite for Northern anchovy and Pacific sardines are calculated as follows.
TTFcomposite _ ^ 21 x (189 x 10)] = 2.29
B-50
-------
The TTFcomposite for brown pelican is 1.79 and is calculated as follows.
TTFcomposite = j-gjg x ((2.29 x 0.75) + (2.29 x 0.25))] = 1.79
Bald Eagle
Bald eagles are opportunistic foragers, with highly variable diets based on the availability
of prey species. Bald eagles are primarily piscivores, showing a preference for fish when they are
available, but will also often consume various other prey types, as well as carrion (Buehler
2020). Diets of bald eagles inhabiting northern California commonly consisted of Sacramento
sucker (Catostomus occidentalis), hardhead (Mylopharodon conocephalsu), Sacramento
pikeminnow (Ptechocheilus grandis), brown bullhead (Ameiurus nebulosus), common carp
(Cyprinus carpio), tui chub {Gila bicolor), rainbow trout (iOnchorhyncus mykiss), largemouth
bass (Micropterus salmoides), Sacramento perch (Archoptlites interruptus), American coot
(Fulica americana), mallard (Anasplatyrhynchos), western grebe (Aechmophorus occidentalis),
gulls (Larus spp.), pied-billed grebe (Podilymbuspodiceps), common merganser (Mergus
merganser), and other diving ducks (U.S. FWS 2017; Hunt et al. 1992; Jackman et al. 1999). In
the U.S. FWS (2017) report, a generic dietary composition for northern California bald eagles
was estimated to be 71.2% fish, 22.8% bird, and 6% mammal. No mammalian TTFcomposite values
were available, so the modeled diet was rescaled as 15.1% fish and 24.3% birds.
An empirical bird TTF was not available for bald eagle, so the species level TTFof 0.78
based on the piscivorous pied billed grebe was used (Table B-6), as it is the only empirically-
derived TTF for a bird species with a largely piscivorous diet, and there are no empirically-
derived TTFs for bird eating birds. Because they consume a wide range of fish species depending
on local availability, the fish portion of their diet was modeled using the median TTFcomposite of
2.35 for all fish species shown in (Table B-14). Because they consume a wide range of bird
species depending on local availability, the bird portion of their diet was modeled using the
median TTFcomposite of 1.93 for all bird species (except for bald eagle) shown in (Table 5-5) and
(Table 5-6). The TTFcomposite for the bald eagle is 1.75 and is calculated as follows.
TTFcomposite = [q 78 x (2.35 x 0.757)] + [0.78 x (1.93 x 0.243)] = 1.75
B-51
-------
Ridgway's Rail
The Ridgway's rail is an omnivorous species with a highly variable diet (Eddleman and
Conway 2020). As reported by U.S. FWS (2017), on average, animal matter accounted for
roughly 85% of Ridgway's rails diet with the remainder being composed of seed and hull
fragments of marsh cordgrass. Moffitt (1941) identified the stomach contents of eighteen
Ridgway's rails and found that the animal matter portion of their overall diet consisted of
approximately 56.5% plaited horse mussels (Modiolus demissus), 15% spiders (Lycosidae), 7.6%
macoma clams (Macoma balthica), 3.2% yellow shore crabs (Hemigrapsis oregonesis), 2%
worn-out nassa snails (Ilyanassa obsoletus), and 1.1% worms, insects, and carrion (combined).
The remaining 15% of their diet consisted of plant matter. Based on this information, the
Ridgway's rail's diet is modeled as consisting of 15% plant matter, 66% mollusks, 3% crabs, and
16% other invertebrates.
An empirical TTF for Ridgway's rail was not available, so the TTF for this species was
calculated using paired data from the closely related American coot (also from the order
Gruiformes). The Ridgway's rail species TTF value, based on a diet consisting of 15% plants and
85%) animals is 0.96 (Table B-9). The invertebrate TTFs are as follows: 4.29 (mollusks), 1.46
(crabs - crayfish surrogate), and 1.89 (all invertebrates), respectively (Table 5-1). The
jjpcomposite for Ridgway's rail is 3.19 and calculated as follows.
TTFcomposite = [q 96 x 0.15] + [0.96 x ((4.29 x 0.66) + (1.41 x 0.03) + (1.89 x 0.16))] =
3.19
Light-Footed Ridgway's Rail
Like the Ridgway's rail, the light-footed Ridgway's rail is an opportunistic forager and
omnivore with a highly variable diet (U.S. FWS 2003). U.S. FWS (2017) reported that light-
footed Ridgway's rail consume a variety of salt marsh invertebrates, such as mussels, snails,
fiddler and hermit crabs, fish, crayfish, isopods, and beetles. Prey fish species include the
California killifish and flathead grey mullet (U.S. FWS 1985). U.S. FWS (2003) assumed that
light-footed Ridgway's rail diet was 10% crayfish and 10% fish, leaving the remaining 80% to
be aquatic invertebrates. Based on this information, the light-footed Ridgway's rail dietary
composition was assumed to be 10% crayfish, 10% fish, and 80% other invertebrates.
B-52
-------
An empirical-species TTF for light-footed Ridgway's rail was not available, so the TTF
for this species was calculated using paired data from the closely related American coot (also
from the order Gruiformes). The light-footed Ridgway's rail species TTF value, based on a diet
consisting of 100% animals, is 0.90 (Table B-l 1). The invertebrate portion of their diet was
modeled using TTFs of 1.46 (crayfish) and 1.89 (all invertebrates) from Table 5-1. The
piscivorous portion of their diet was modeled as 50% California killifish and 50% flathead gray
mullet. Composite TTFs were not available for either of these fish species in (Table B-14), so
j-j-j,-composite vaiues were calculated below.
Dietary information for California killifish (Fundulusparvipinnis) was obtained from
Nature Serve
(https://explorer.natureserve.org/Taxon/ELEMENT GLOBAL.2.103892/Fundulus parvipinnis).
which noted the species is an invertivore that feeds primarily on arthropods, as well as annelids,
gastropods, and fish eggs. Based on this information, their diet was modeled as consisting of
100%) invertebrates. The TTFcomposite for California killifish is calculated as follows, using a
genus-level fish TTF of 1.27 (Fundulus) from (Table 5-2) and a dietary TTF of 1.89 (all
invertebrates) from (Table 5-1).
TTFcomposite _ ^121 x (1.89 X 1.0)] = 2.40
Dietary information for the flathead grey mullet was obtained from FishBase
(https://www.fishbase.se/summarv/Mugil-cephalus.htmn which noted that the species consumes
a mix of zooplankton, benthic invertebrates, algae, and detritus. Based on this information, the
diet of flathead gray mullet was modeled as 50% zooplankton and 50% benthic invertebrates.
The TTFcomposite for flathead grey mullet is calculated as follows, using a class-level fish TTF of
1.21 (Actinopterygii) from (Table 5-2) and dietary TTF of 1.89 (zooplankton) and 1.68 (benthic
invertebrates - median TTF of all benthic crustaceans, benthic insects, and annelids) from (Table
5-1).
TTFcomposite = [121 x (1.89 x 0.5)] + [1.21 x (1.68 x 0.5)] = 2.16
The TTFcomposite for light footed Ridgway's rail is 1.70 and is calculated as follows.
B-53
-------
TTFcomposite = |q gQ x gg x g g~) + (1-46 x Q.l))]
+ [0.90 x ((2.40 x 0.05) + (2.16 x 0.05))] = 1.70
Yuma Ridgway's Rail
As reported by U.S. FWS (2017), the dietary composition of Yuma Ridgway's rail is
dominated by two species of crayfish. Ohmart and Tomlinson (1977) found that approximately
95% of the stomach contents of two Yuma Ridgway's rails consisted of crayfish. Other prey
items consumed by Yuma Ridgway's rails include small fish, insects, amphibian larvae, clams,
and other aquatic invertebrates (U.S. FWS 2010, 2017). Based on this information, the Yuma
Ridgway's rail diet was modeled as 95% crayfish and 5% other aquatic invertebrates, as U.S.
FWS (2003) indicated that fish do not appear to be an important dietary item for Yuma
Ridgway's rail residing outside of the Colorado River Delta in Mexico.
An empirical TTF for Yuma Ridgway's rail was not available, so the species TTF was
calculated as 0.90 using paired data from the closely related American coot (also from the order
Gruiformes), based on a diet consisting of 100% animals (Table B-l 1). The invertebrate T'/T's
are 1.46 (crayfish) and 1.89 (all invertebrates) from (Table 5-1). The TTFcomposite for Yuma
Ridgway's rail is 1.33 and is calculated as follows.
TTFcomposite = |q_90 x ((1.46 x 0.95) + (1.89 x 0.05))] = 1.33
Black Rail
U.S. FWS (2017) reports that dietary information for black rail is limited and notes that
this species is likely an opportunistic forager with a variable diet dependent on food availability.
This species consumes invertebrates and seeds. Eddleman et al. (2020) indicated that the dietary
composition of nesting black rails consisted of 73% predaceous diving, ground, and other
beetles, 14% earwigs, 13% bulrush seeds, and trace amounts of cattail. Based on this
information, the black rail diet was modeled as 13% plant matter and 87% aquatic invertebrates.
An empirical TTF for black rail was not available, so the TTF was calculated using paired
data from the closely related American coot (also from the order Gruiformes). The black rail
species TTF value, based on a diet consisting of 13% plants and 87% animals, is 0.95 (Table
B-54
-------
B-10). The invertebrate portion of the black rail diet was modeled using an all-invertebrate TTF
of 1.89 (Table 5-1). The TTFcomposite for black rail is 1.69 and is calculated as follows.
TTFcomposite = [0.95 x 0.13] + [0.95 x 1.89 x 0.87] = 1.69
Least Tern
Least tern consume a variety of shallow-bodied small fish species (<8 cm in length)
(Atwood and Kelly 1984, Thompson et al. 2020). In California, the least tern diet is comprised of
shallow-bodied small fish species (<8 cm) and smaller young of the year fish from larger species
found in shallow waters such as estuaries, nearshore waters and river mouths (U.S. FWS 2017,
2020). Their diet has been known to include up to 50 different fish species (U.S. FWS 1985,
2017). The distributions of prey species based on dropped prey were surveyed at Alameda Point,
in the San Francisco Bay (Elliot 2008), and at sites in Southern California (Atwood and Kelly
1984). The most abundant prey species were silversides, particularly topsmelt (Atherinops
affinis) and jacksmelt (A. californiensis). The next most abundant prey species was the northern
anchovy (Engraulis mordax). These three species were the most abundant in both studies,
comprising around 75-80% of dropped prey items. Other relatively abundant species included
Pacific herring (Clupeapallasii) in the San Francisco Bay region, and California killifish
(Fundulusparvipinnis) at the Southern California sites (Atwood and Kelly 1984; Elliott 2008).
Based on this information in U.S. FWS (2017) report, the dietary composition of the least
tern was assumed to be 100% fish. The least tern diet was modeled as 30% topsmelt, 30%
jacksmelt, 20% northern anchovy, 10% Pacific herring, and 10% California killifish. Although
California least-tern have been shown to consume up to 50 fish species, these five species
represent the most abundant species in the California least tern diet, and are all small, relatively
shallow bodied species that are regularly consumed.
An empirical TTF was not available for the least tern, so the surrogate species TTF value
was the pied-billed grebe TTF of 0.78 (Table B-6), a piscivorous bird with a similar diet.
Composite T'/T's for the fish species modeled to comprise the least tern diet (topsmelt, jacksmelt,
Pacific herring, northern anchovy, California killifish) are not available in Table B-14, so
j-j-j,-composite vaiues were calculated below.
B-55
-------
Dietary information for topsmelt was obtained from FishBase
(https://www.fishbase.de/summary/Atherinops-affinis.htmn. which notes adults tend to feed on
zooplankton while juveniles will feed on algae and kelp fly larvae. Based on this information, the
topsmelt diet was modeled as 50% zooplankton and 50% insects. No TTF for topsmelt was
available, or for a closely related surrogate species, so a class-level (Actinopterygii) TTF of 1.21
was used to represent this species (Table 5-2). The TTF for zooplankton is 1.89 and the median
TTF for all insect orders is 2.14 (Table 5-1). The TTFcomposite for topsmelt is calculated as
follows.
TTFcomposite = [ 121 x (189 x 0.50)] + [1.21 x (2.14 x 0.50)] = 2.44
Dietary information for jacksmelt (https://www.fishbase.se/summarv/Atherinopsis-
californiensis.htmQ and Pacific herring (https://www.fishbase.se/summary/1520) were obtained
from FishBase, which note these species feed predominantly on zooplankton. Based on this
information, the jacksmelt and Pacific herring diets were calculated as 100% zooplankton, using
a TTF of 1.89 (Table 5-1). No TTF for jacksmelt or Pacific herring were available, or for a
closely related surrogate species, so a class-level (Actinopterygii) TTF of 1.21 was used to
represent this species (Table 5-2). The TTFcomposite for jacksmelt and Pacific herring is calculated
as follows.
TTFcomposite _ [ 121 X 1.89 X 1.0] = 2. 29
Dietary information for northern anchovy is described above in the description of the
brown pelican diet. The TTFcompos,te for northern anchovy is 2.29. Finally, dietary information for
California killifish is described above in the description of the light-footed Ridgway's rail diet.
The TTFcomposite for California killifish is 2.40. The TTFcomposite for the least tern is 1.84 and is
calculated as follows.
YYFcomP°site = [o 78
X ((2.44 X 0.30) + (2.29 X 0.30) + (2.29 X 0.20) + (2.29 X 0.10)
+ (2.40 X 0.10))] = 1.84
B-56
-------
Summary
Composite TTFs could be calculated for eight T&E bird species using paired dietary
information from surrogate species to calculate surrogate TTFs. TTp^omposite for these species are
listed in Table 5-6.
Calculation of Fish TTFcomposite for Bird Food Web Modeling
The fish TTFc"mP"site usecj to calculate avian jjpcomP"site for the six bird species that
consume fish as part of their diet (pied billed grebe, American dipper, brown pelican, bald eagle,
light-footed Ridgway's rail, and least tern) was determined as follows. Table B-14 (below)
provides the fish TTFcomposite values for the 32 fish species with an available TTF (Table 5-2).
These TTFs encompass a diverse range of species, representing eight fish orders. For bird species
that consume a wide range of fish species, the median TTp^omposite 0f 32 fish species (2.35)
was used as a representative fish TTFcomposite. For bird species that consume a relatively small
number of fish species, representative TTFcomposite values were used if available, or TTFcomposite
values were calculated for fish species not listed in the table below. Fish TTFcomposite were
obtained from Appendix B of U.S. EPA (2016a).
B-57
-------
Table B-14. Fish TTpcomPosUe for the 32 species with empirically derived TTF.
Common name
Scientific name
TTF
rprpjjc°mp°site
Cypriniformes
blacknose dace
Rhinichthys atratulus
0.71
1.29
bluehead sucker
Catostomus discobolus
1.04
1.24
Ion«nosesucker
Catostomus catostomus
0.90
1.34
white sucker
Catostomus commersonii
1.11
1.58
flannelmouth sucker
Catostomus latipinnis
0.98
1.52
common carp
Cyprinus carpio
1.20
1.58
creek chub
Semotilus atromaculatus
1.06
1.55
fathead minnow
Pimephales promelas
1.57
2.78
red shiner
Cyprimlla lutrensis
1.31
2.27
redside shiner
Richardsonius balteatus
1.08
2.48
sand shiner
Notropis stramineus
1.56
2.43
Cyprinodontiformes
western mosquitofish
Gambusia afftnis
1.21
2.37
northern plains killifish
Fundulus kansae
1.27
2.44
Esociformes
northern pike
Esox Lucius
1.78
4.02
Gasterosteiformes
brook stickleback
Culaea inconstans
1.79
2.47
Perciformes
black crappie
Pomoxis nigromacirfatus
2.67
5.66
bluegill
Lepomis macrochirus
1.03
2
green sunfish
Lepomis cyanellus
1.12
2.29
largemouth bass
Micropterus salmoides
1.39
3.04
smallmouth bass
Micropterus dolomieu
0.86
1.93
striped bass
Morone saxatilis
1.48
3.23
walleye
Sander vitreus
1.60
3.21
yellow perch
Perca flavescens
1.42
2.47
Salmoniformes
B-58
-------
Common name
Scientific name
TTF
rprpjjc°mp°site
brook trout
Salvelimis fontinalis
0.88
1.96
brown trout
Salmo trutta
1.38
2.78
mountain whitefish
Pros opium w illiamsoni
1.38
2.97
cutthroat trout
Oncorhynchus clarkii
1.12
2.29
rainbow trout
Oncorhynchus mykiss
1.07
2.33
Scorpaeniforme
mottled sculpin
Cottus bairdi
1.38
2.72
sculpin
Cottus sp.
1.29
2.66
Siluriformes
black bullhead
Ameiurus melas
0.85
1.72
channel catfish
Ictalurus punctatus
0.68
1.35
B-59
-------
Appendix C Total Selenium and Dissolved Selenium
Concentrations in California Water Bodies
Information Summary
Data Source: California Environmental Data Exchange Network (CEDEN).
Description: The total selenium and dissolved selenium concentrations in California water bodies
were collected over a 10-year period from October 5, 2004 to June 3, 2014. The data were
downloaded from the CEDEN database, which was last accessed on February 4, 2015. The
assigned HUC12 was used as the identifier for the water body name where total selenium and/or
dissolved selenium concentrations in water samples were reported. The data summary tables
shown below were developed using the Microsoft Excel pivot table function. The level of
confidence in the environmental data is high because the CEDEN database from which the data
were derived for this analysis is the most comprehensive and largest source of selenium
environmental monitoring data collected in California. The sample sites are not, however,
randomly selected.
Table C-l. Total Selenium Concentrations in California Water Bodies.
Number
Minimum
Mean
Maximum
of
Se
Se
Se
California Regional Board Sampling Sites (HUC12)
Samples
Qig/L)
Qig/L)
Qig/L)
Central Coast Regional Board (6 HUC12 Sites)
8
1.6
6.9
14.6
Chorro Creek
2
1.6
2.6
3.7
Corralitos Canyon
1
14.6
14.6
14.6
Dos Pueblos Canyon-Frontal Santa Barbara Channel
1
12.4
12.4
12.4
Lower Arroyo Grande Creek
1
10.4
10.4
10.4
Lower San Luis Obispo Creek
1
5.8
5.8
5.8
Oso Flaco Creek
2
1.9
3.3
4.6
Central Valley Regional Board (114 HUC12 Sites)
10637
0.0
12.8
1591.0
Agua Fria Creek
14
0.6
1.5
3.9
Anderson Creek-Sacramento River
2
1.0
2.0
3.0
Ash Slough-Fresno River
1
5.0
5.0
5.0
Bear Creek
17
0.1
0.6
2.0
Bennett Valley-San Joaquin River
53
0.0
2.0
9.2
C-l
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
(Hg/L)
Maximum
Se
(Hg/L)
Berenda Slough
4
0.1
0.2
0.5
Big Buttonwillow Lake-Salt Slough
18
0.3
0.6
(L7)
Boggs Slough-Fresno Slough
1
0.1
0.1
0.1
Bolinas Bay
8
0.0
0.1
0.2
Boscha Lake (Historical)-Stanislaus River
4
0.2
0.9
(2.3)
Brooks Creek-Cache Creek
2
1.0
1.0
1.0
Brush Creek-South Fork American River
1
0.9
0.9
0.9
Caesar Ditch-Cross Creek
3
1.0
1.0
1.0
Chanac Creek
1
10.0
10.0
10.0
Deadmans Slough-Salt Slough
305
0.0
0.6
4.1
Deep Slough-Bear Creek
22
0.1
0.4
1.6
Druinheller Slough-Butte Creek
3
0.2
0.2
0.2
East Branch Cross Creek-Cross Creek
1
2.0
2.0
2.0
Escarpado Canyon-Panoche Creek
12
6.2
10.0
18.0
Fancher Creek Canal
6
0.1
0.2
0.4
Fresno Slough
16
0.2
3.0
6.5
Gilsizer Slough-Snake River
4
1.0
1.3
2.0
Hog Slough
17
0.1
0.1
0.3
Hospital Creek
25
0.2
0.7
1.6
Ingrain Creek
30
0.3
1.2
2.9
Jones Drain-Merced River
23
0.0
0.6
5.1
Kern Canyon-San Joaquin River
28
0.1
0.9
2.6
Laguna Seca Creek
353
0.02
40.2
167
Lake Ramona-San Joaquin River
332
0.01
1.3
(3.7)
Lake Success-Tule River
1
1.0
1.0
1.0
Little Creek
4
1.0
1.3
2.0
Lone Willow Slough-San Joaquin River
15
0.1
1.0
5.3
Los Banos Creek
31
0.2
1.9
5.1
Los Sauces Creek-Frontal Pacific Ocean
1
7.5
7.5
7.5
Lower Bear Creek
21
0.1
0.2
0.9
Lower Cantua Creek
18
0.4
3.0
7.6
Lower Cottonwood Creek
14
0.1
0.3
0.8
Lower Del Puerto Creek
24
0.3
1.1
3.4
Lower Dry Creek
7
0.1
0.4
0.6
Lower Duck Creek
13
0.1
0.1
0.6
Lower Elk Bayou
1
1.0
1.0
1.0
Lower Freshwater Creek
2
1.0
1.0
1.0
Lower Kellogg Creek
7
0.3
1.1
3.0
C-2
-------
Nu in her
(>r
( iililoi'iiiii Regional lioard Sampling Silos (III (12) Samples
Minimum
So
(.ug/l.)
Mean
Se
(.ug/l.)
Maximum
Se
(.ug/l.)
Lower Laguna
1
(3.0)
(3.0)
(3.0)
Lower Little Panoche Creek
1
15.0
15.0
15.0
Lower Logan Creek
2
1.0
1.5
2.0
Lower Lone Tree Creek
4
0.2
0.4
0.8
Lower Los Gatos Creek
19
0.0
2.4
6.5
Lower Mariposa Slough-Deadman Creek
37
0.1
0.6
3.0
Lower Marsh Creek
33
0.6
2.2
6.0
Lower Owens Creek
8
0.3
0.5
0.8
Lower Poso Slough-Salt Slough
30
0.1
0.7
1.8
Lower Ulatis Creek
11
0.3
1.3
3.0
Lower Walker Creek
1
0.1
0.1
0.1
Lower West Side Canal
63
0.2
1.2
6.7
Lower White Lake-San Joaquin River
249
0.0
0.9
(4.9)
Mariposa Creek-Duck Slough
32
0.1
0.4
1.0
Markley Canyon-San Joaquin River
7
0.1
0.1
0.1
McGrath Lake-Frontal Pacific Ocean
2
0.5
0.6
0.6
McLeod Lake-Mormon Slough
6
0.1
0.4
0.8
Middle Elk Bayou
3
1.0
1.0
1.0
Middle Lone Tree Creek
5
0.2
1.0
3.0
Middle River-San Joaquin River
16
0.1
0.2
0.5
Modesto Reservoir-Dry Creek
13
0.1
0.3
1.0
Moreno Gulch
961
0.0
14.5
120
Mosquito Creek-Cross Creek
4
0.2
0.7
1.0
Mud 1085 Dam-Fresno Slough
2
4.2
4.8
5.5
Mud Slough
3685
0.01
27.7
1591
Murphy Creek-Mokelumne River
4
0.1
0.7
2.0
Mustang Creek-Los Banos Creek
40
0.2
0.6
2.1
North Branch Tule River-Tule River
6
1.0
1.2
2.0
Old Channel Tule River
5
1.0
1.2
2.0
Oso Creek-Orestimba Creek
70
0.0
2.0
9.1
Packer Lake-Sacramento River
1
0.5
0.5
0.5
Pear Slough-San Joaquin River
2294
0.0
1.4
4.7
Ping Slough-Coon Creek
1
1.0
1.0
1.0
Pixley Slough
2
0.3
0.4
0.6
Porter Slough
4
1.0
1.3
2.0
Red Bridge Slough-San Joaquin River
215
0.0
0.7
3.8
Riley Slough
21
0.1
0.1
0.3
Roberts Island-Trapper Slough
24
0.1
0.5
1.5
C-3
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
Qig/L)
Maximum
Se
(Hg/L)
Rock Creek-Pit River
2
0.1
0.1
0.1
Rodden Creek-Stanislaus River
2
0.1
0.1
0.1
Saint Johns River
4
0.7
1.2
2.0
Salt Creek
6
0.3
0.5
0.8
Shag Slough-San Joaquin River
322
0.0
0.5
4.1
Simmons Creek-Littlejohns Creek
7
0.2
0.3
0.4
South Branch Island Canal-Kings River
6
0.1
0.3
0.7
South Slough-Deadman Creek
21
0.1
0.3
1.2
Stockton Diverting Canal-Calaveras River
1
0.8
0.8
0.8
Stone Corral Canyon-Cottonwood Creek
5
0.3
1.1
2.0
Stone Corral Creek
2
0.5
0.6
0.7
Sycamore Slough
35
0.1
0.3
1.2
Telephone Cut-Bishop Cut
3
0.1
0.1
0.1
Threemile Slough-Sacramento River
5
0.1
0.1
0.2
Toe Drain-Cache Slough
6
0.2
1.3
6.0
Town of Famoso-Poso Creek
2
0.8
0.9
1.0
Town of Hilmar-San Joaquin River
21
0.1
0.9
2.0
Town of Lemoore-Kings River
1
0.8
0.8
0.8
Town of Riverdale Park-Tuolumne River
5
0.0
0.3
0.9
Town of Terra Bella-Deer Creek
3
1.0
1.3
2.0
Tule Canal-Toe Drain
10
1.0
3.5
7.8
Turlock Lake
7
0.3
0.5
1.0
Union Island
22
0.3
1.4
3.0
Upper Lone Tree Creek
4
0.1
0.2
0.3
Upper Marsh Creek
3
1.0
1.0
1.0
Upper Poso Slough
15
0.6
8.4
21.0
Upper Ruth Lake-Mud Slough
353
0.0
1.2
(5.0)
Upper West Side Canal
5
0.3
1.0
1.7
Venice Island-Little Connection Slough
6
0.1
0.1
0.2
Walker Slough-French Camp Slough
13
0.1
0.3
1.0
Walthall Slough-San Joaquin River
39
0.1
0.2
0.9
Wildcat Canyon
346
0.0
1.0
5.7
Wilson Creek-North Honcut Creek
3
0.1
0.3
0.6
Lahontan Regional Board (2 HUC12 Sites)
18
0.2
0.6
1.9
Mammoth Creek
16
0.2
0.4
0.7
Tecopa Wash-Amargosa River
2
1.4
1.7
1.9
C-4
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
(Hg/L)
Maximum
Se
(Hg/L)
Los Angeles Regional Board (45 HUC12 Sites)
116
0.4
16.4
335.0
Abadi Creek-Sespe Creek
2
1.0
1.9
2.8
Alhambra Wash-Rio Hondo
1
5.1
5.1
5.1
Arroyo Sequit-Frontal Pacific Ocean
5
1.2
2.2
3.4
Big Sycamore Canyon
2
2.1
2.6
3.1
Boulder Creek-Sespe Creek
3
1.0
9.3
25.6
Cedar Creek-Piru Creek
1
1.0
1.0
1.0
Cold Creek-Malibu Creek
11
1.2
3.7
6.8
Coyote Creek
1
0.9
0.9
0.9
Coyote Creek-San Gabriel River
1
1.3
1.3
1.3
Elizabeth Lake Canyon
2
0.6
1.3
(2.1)
Fish Creek-Piru Creek
2
0.9
1.1
1.3
Garapito Creek
2
0.7
1.7
2.7
Harmon Canyon-Santa Clara River
1
9.2
9.2
9.2
Hopper Canyon
1
1.7
1.7
1.7
Hosier Canyon-Piru Creek
3
2.0
3.4
4.7
Iron Fork-San Gabriel River
1
1.1
1.1
1.1
Las Posas Arroyo
1
7.6
7.6
7.6
Las Virgenes Creek
14
7.7
70.8
335
Lockwood Creek
1
1.5
1.5
1.5
Los Sauces Creek-Frontal Pacific Ocean
7
7.8
24.5
42.6
Lower Conejo Arroyo
2
4.5
4.7
5.0
Lower Ventura River
3
0.8
1.9
3.0
Lower West Fork San Gabriel River
1
0.5
0.5
0.5
Matilija Creek
1
1.8
1.8
1.8
McGrath Lake-Frontal Pacific Ocean
3
0.8
(2.1)
(4.6)
Medea Creek
12
3.8
10.9
36.5
Mugu Lagoon
1
55.2
55.2
55.2
North Fork San Gabriel River
1
0.8
0.8
0.8
Pole Creek-Santa Clara River
1
4.0
4.0
4.0
Salt Canyon-Santa Clara River
7
1.5
4.3
6.6
San Antonio Creek
1
3.4
3.4
3.4
San Francisquito Canyon
2
0.6
0.7
0.7
Santa Fe Flood Control Basin-San Gabriel River
2
0.4
4.4
8.4
Santa Monica Beach-Frontal Santa Monica Bay
1
1.6
1.6
1.6
Santa Paula Creek
1
298
298
298
Snowy Creek-Piru Creek
1
0.7
0.7
0.7
Solstice Canyon-Frontal Santa Monica Bay
2
3.4
4.7
6.0
C-5
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
Qig/L)
Maximum
Se
Qig/L)
South Fork Santa Clara River
1
6.4
6.4
6.4
Timber Canyon-Santa Clara River
1
2.5
2.5
2.5
Tule Creek-Sespe Creek
5
0.6
1.1
2.5
Upper Bouquet Canyon
1
0.9
0.9
0.9
Upper Conejo Arroyo
1
6.4
6.4
6.4
Upper Simi Arroyo
1
8.5
8.5
8.5
Upper Ventura River
1
1.3
1.3
1.3
Zuma Canyon-Frontal Pacific Ocean
1
2.1
2.1
2.1
North Coast Regional Board (56 HUC12 Sites)
352
0.1
1.0
126.0
Alder Creek-Big Sulphur Creek
5
0.1
0.3
0.4
Bear Creek-Eel River
5
0.1
0.2
0.3
Bittenbender Creek-Klamath River
3
0.1
0.2
0.4
Brooks Creek-Russian River
8
0.1
0.3
0.6
Brush Creek-Klamath River
2
0.2
0.4
0.6
Bunton Hollow Creek-Shasta River
8
0.3
0.9
1.9
Burright Creek-East Fork Russian River
5
0.1
0.2
0.3
Butte Creek-South Fork Eel River
3
0.7
0.8
1.0
Cameron Creek-Eel River
11
0.1
0.4
1.0
Canoe Creek-South Fork Eel River
12
0.2
0.4
0.9
Cummings Creek-Van Duzen River
1
0.8
0.8
0.8
Deadwood Creek-Trinity River
3
0.1
0.3
0.7
Deerhorn Creek-Trinity River
8
0.1
0.4
1.0
Division Creek-Eel River
10
0.1
0.4
0.8
Dutch Bill Creek-Russian River
12
0.1
0.5
1.2
East Fork Russian River-Russian River
10
0.1
0.4
0.7
Elder Creek-South Fork Eel River
12
0.1
0.4
0.9
Elk River
2
0.7
0.8
0.9
Empire Creek-Klamath River
3
0.1
0.2
0.4
Estero Americano
1
1.0
1.0
1.0
Freshwater Creek
3
0.7
0.7
0.8
Gill Creek-Russian River
14
0.1
0.3
0.7
Goforth Creek-Middle Fork Eel River
13
0.3
0.6
1.1
Hardscrabble Creek-Smith River
8
0.2
0.4
0.9
Jacoby Creek
1
0.9
0.9
0.9
Kohl Creek-Klamath River
3
0.1
0.3
0.4
Lake Mendocino-East Fork Russian River
4
0.2
0.3
0.5
Little River
1
0.6
0.6
0.6
C-6
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
(Hg/L)
Maximum
Se
(Hg/L)
Little Salmon Creek-Salmon Creek
9
0.6
1.2
2.4
Lower Garcia River
3
0.7
1.0
1.6
Lower Indian Creek
2
1.6
63.8
126.0
Lower Mattole River
2
0.6
0.6
0.7
Lower North Fork Eel River
6
0.2
0.4
0.9
Lower Santa Rosa Creek
19
0.4
2.3
9.7
Lower South Fork Smith River
6
0.1
0.2
0.3
McArthur Creek-Redwood Creek
12
0.2
0.4
0.7
Middle Garcia River
1
0.8
0.8
0.8
Mill Creek-Mad River
10
0.1
0.3
0.7
Mingo Creek-South Fork Trinity River
7
0.2
0.4
1.0
Morrison Creek-Russian River
2
0.2
0.2
0.2
North Fork Mattole River
2
0.6
0.7
0.7
Orrs Creek-Russian River
10
0.2
0.4
1.1
Porter Creek-Mark West Creek
21
0.1
1.0
2.6
Russian Gulch-Frontal Pacific Ocean
1
0.8
0.8
0.8
Salmon Creek
4
0.7
0.8
0.9
Sharber Creek-Trinity River
1
0.7
0.7
0.7
Slate Creek-Klamath River
5
0.1
0.3
0.5
Smith River
7
0.1
0.2
0.5
South Fork Gualala River-Gualala River
9
0.1
0.7
2.4
Thomas Creek-Eel River
6
0.1
0.5
1.0
Town of Scott Bar-Scott River
11
0.1
0.4
0.8
Upper Garcia River
1
0.7
0.7
0.7
Upper Indian Creek
1
7.8
7.8
7.8
Ward Creek-Austin Creek
5
0.2
0.5
0.8
West Slough-Dry Creek
11
0.1
0.3
0.6
Yreka Creek
7
0.1
0.5
1.0
San Diego Regional Board (30 HUC12 Sites)
53
0.6
4.5
24.1
Aliso Creek
3
10.9
13.5
18.2
Arroyo Trabuco
1
11.6
11.6
11.6
Boden Canyon-Santa Ysabel Creek
1
1.8
1.8
1.8
Boulder Creek
1
0.6
0.6
0.6
Buena Vista Creek
1
6.4
6.4
6.4
Cedar Creek
1
1.4
1.4
1.4
Conejos Creek
2
1.3
1.8
2.4
Dan Price Creek-Santa Ysabel Creek
1
1.2
1.2
1.2
C-7
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
(Hg/L)
Maximum
Se
(Hg/L)
El Capitan Reservoir-San Diego River
2
0.7
0.8
0.9
Forester Creek
1
7.7
7.7
7.7
Los Penasquitos Creek
1
7.7
7.7
7.7
Lower Escondido Creek
3
4.7
5.9
8.2
Lower Otay Reservoir
2
(3.2)
(3.4)
(3.6)
Lower Pine Valley Creek
1
1.0
1.0
1.0
Lower San Juan Creek
4
2.4
9.4
15.0
McAlmond Canyon-Cottonwood Creek
1
1.9
1.9
1.9
Middle Pine Valley Creek
3
1.9
2.5
3.0
Middle San Mateo Creek
4
0.8
1.3
1.9
Morena Reservoir-Cottonwood Creek
1
(6.3)
(6.3)
(6.3)
Paradise Creek-San Luis Rey River
1
1.8
1.8
1.8
Prima Deshecha Canada-Frontal Capistrano Bight
1
24.1
24.1
24.1
Rainbow Creek-Santa Margarita River
4
1.7
2.4
3.4
Ritchie Creek-San Diego River
2
1.5
1.5
1.6
Salt Creek-Frontal Gulf of Santa Catalina
1
7.8
7.8
7.8
San Marcos Creek
1
4.3
4.3
4.3
San Pasqual Valley-Santa Ysabel Creek
1
5.2
5.2
5.2
Sandia Canyon
1
4.7
4.7
4.7
Upper Pine Valley Creek
2
1.0
2.4
3.9
Upper San Juan Creek
3
0.9
1.4
2.1
Upper San Mateo Creek
2
1.0
1.1
1.3
San Francisco Bay Regional Board (7 HUC12 Sites)
99
0.03
1.3
4.8
Calabazas Creek-Frontal San Francisco Bay Estuaries
2
0.3
0.4
0.5
Denniston Creek-Frontal Pacific Ocean
47
0.6
1.7
4.8
Dry Creek-Arroyo Valle
6
0.2
0.6
2.0
Guadalupe River
3
1.2
1.3
1.6
San Leandro Creek
4
0.2
0.2
0.3
Walnut Creek-Frontal Suisun Bay Estuaries
6
0.5
2.7
4.4
Ward Creek-Frontal San Francisco Bay Estuaries
31
0.0
0.6
2.9
Santa Ana Regional Board (10 HUC12 Sites)
12
0.1
1.2
5.1
East Twin Creek
1
0.4
0.4
0.4
Fish Creek-Santa Ana River
1
0.3
0.3
0.3
Moreno Valley
1
1.4
1.4
1.4
North Fork San Jacinto River
1
0.6
0.6
0.6
San Antonio Canyon
2
0.5
0.6
0.6
C-8
-------
Number
Minimum
Mean
Maximum
of
Se
Se
Se
California Regional Board Sampling Sites (HUC12)
Samples
Qig/L)
Qig/L)
Qig/L)
San Timoteo Canyon-San Timoteo Wash
1
1.0
1.0
1.0
Santa Anna Wash-Santa Anna River
1
0.3
0.3
0.3
Strawberry Creek-San Jacinto River
2
0.1
0.2
0.3
Upper Cliino Creek
1
5.1
5.1
5.1
Upper San Diego Creek
1
3.9
3.9
3.9
Grand Total 11290
Data Source: California Environmental Data Exchange Network (CEDEN).
Data includes reported Total Se in water samples collected from October 5, 2004 to June 3, 2014.
CEDEN was last accessed on February 4, 2015.
San Francisco Bay Regional Board summary excludes San Francisco Bay selenium data.
Bolded sampling sites indicate a lentic system (lakes and reservoirs).
Bolded numbers in parenthesis indicate that total selenium exceeded 1.5 |ig Se/L in lentic systems.
Bolded numbers indicate that total selenium exceeded 3.1 |ig Se/L in lotic systems.
HUC12 is Hydrologic Unit Code 12. The HUC12 designation is the name of sampling site.
Table C-2. Dissolved Selenium Concentrations in California Water Bodies.
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
(Ug/L)
Mean
Se
(Ug/L)
Maximum
Se
(Ug/L)
Central Valley Regional Board (38 HUC12 Sites)
178
0.01
2.7
106
Black Butte Dam-Stony Creek
1
1.2
1.2
1.2
Bolinas Bay
8
0.02
0.4
2.7
Boscha Lake (Historical)-Stanislaus River
1
0.1
0.1
0.1
Compton Creek-Los Angeles River
1
1.6
1.6
1.6
Deadmans Slough-Salt Slough
4
0.2
0.7
1.2
Drumheller Slough-Butte Creek
2
0.2
1.5
2.8
Hoag Slough-Sacramento River
2
0.02
0.3
0.5
Hog Slough
2
0.1
0.4
0.7
Ingalsbe Slough-Merced River
2
1.5
2.1
2.7
Jack Slough
2
0.2
0.6
1.1
Jones Drain-Merced River
1
0.1
0.1
0.1
Laguna Seca Creek
4
0.2
1.8
4.6
Lake Ramona-San Joaquin River
4
0.1
0.6
1.4
Lower Antelope Creek
2
0.6
0.7
0.7
Lower Poso Slough-Salt Slough
2
0.3
1.1
1.9
Lower White Lake-San Joaquin River
4
0.2
1.0
(2.0)
C-9
-------
Number
Minimum
Mean
Maximum
of
Se
Se
Se
California Regional Board Sampling Sites (HUC12)
Samples
Qig/L)
Qig/L)
(Hg/L)
McLeod Lake-Mormon Slough
2
0.1
0.6
1.1
Middle Dry Creek
2
1.3
1.8
2.3
Middle Walker Creek
1
0.8
0.8
0.8
Modesto Reservoir-Dry Creek
2
1.2
1.3
1.4
Moreno Gulch
11
0.1
1.3
2.2
Mud Slough
43
0.03
5.1
40.9
Oso Creek-Orestimba Creek
4
0.1
0.5
0.9
Pear Slough-San Joaquin River
25
0.01
1.0
2.4
Pixley Slough
2
0.1
0.3
0.5
Red Bridge Slough-San Joaquin River
4
0.2
0.5
0.7
Red Spring-Colorado River
12
0.7
11.7
106
Shag Slough-San Joaquin River
7
0.03
0.6
2.0
South Fork Ditch-Willow Slough
1
0.8
0.8
0.8
Sycamore Slough
1
0.8
0.8
0.8
Town of French Camp-San Joaquin River
1
1.6
1.6
1.6
Town of Hilmar-San Joaquin River
4
0.2
1.2
2.2
Town of Riverdale Park-Tuolumne River
1
0.1
0.1
0.1
Union Island
3
0.7
1.4
1.8
Upper Ruth Lake-Mud Slough
3
0.2
0.5
1.0
Upper Steelhead Creek
1
0.2
0.2
0.2
Wildcat Canyon
4
0.1
1.3
2.6
Yankee Slough
2
0.1
0.2
0.2
Colorado River Regional Board (16 HUC12 Sites)
201
0.03
6.1
46
Ash Main Canal-Alamo River
23
0.7
7.7
23.7
Cinnabar Wash-Palo Verde Valley
27
0.9
3.7
10.3
City of Indio-Whitewater River
7
1.4
2.3
4.1
Colorado River-Imperial Reservoir
13
(1.6)
(3.2)
(6.4)
Frontal Saltan Sea
2
5.5
5.6
5.7
Gieselmann Lake-Alamo River
6
3.7
6.4
9.7
Guadalupe Creek-Whitewater River
12
0.03
3.7
7.9
Lower New River
17
4.2
12.5
46
Middle New River
2
5.4
5.5
5.6
Ramer Lake-Alamo River
2
6.4
7.8
9.1
Saltan Sea
38
0.7
1.4
4.3
Town of Calipatria-Alamo River
23
0.6
9.4
27.1
Town of El Centra
2
4.2
5.1
6.0
Town of Fuller-Alamo River
4
2.7
9.4
21.0
C-10
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
(Hg/L)
Maximum
Se
(Hg/L)
Town of Niland-Frontal Saltan Sea
4
2.0
5.3
11.7
Upper New River
19
0.1
12.1
38.5
Lahontan Regional Board (2 HUC12 Sites)
18
0.3
0.5
1.4
Mammoth Creek
16
0.3
0.4
0.4
Tecopa Wash-Amargosa River
2
1.0
1.2
1.4
Los Angeles Regional Board (48 HUC12 Sites)
109
0.3
9.1
129
Abadi Creek-Sespe Creek
3
0.8
1.5
2.3
Alamitos Bay
2
0.5
0.9
1.4
Alhambra Wash-Rio Hondo
2
5.3
8.1
10.9
Arroyo Seco
1
4.8
4.8
4.8
Arroyo Sequit-Frontal Pacific Ocean
3
1.0
1.7
2.7
Boulder Creek-Sespe Creek
3
1.3
7.9
20.7
Bull Creek
1
14.6
14.6
14.6
Cedar Creek-Piru Creek
1
0.9
0.9
0.9
Cold Creek-Malibu Creek
11
1.1
4.0
7.2
Compton Creek-Los Angeles River
1
6.5
6.5
6.5
Coyote Creek
1
0.9
0.9
0.9
Coyote Creek-San Gabriel River
1
0.8
0.8
0.8
Elizabeth Lake Canyon
1
(1.6)
(1.6)
(1.6)
Fish Creek-Piru Creek
2
0.9
0.9
0.9
Garapito Creek
2
0.9
1.9
2.9
Harmon Canyon-Santa Clara River
1
9.9
9.9
9.9
Hopper Canyon
1
2.2
2.2
2.2
Hosier Canyon-Piru Creek
3
1.6
3.4
5.2
Iron Fork-San Gabriel River
1
0.9
0.9
0.9
Las Posas Arroyo
1
7.4
7.4
7.4
Las Virgenes Creek
14
9.0
37.5
129
Lockwood Creek
1
0.9
0.9
0.9
Lower Conejo Arroyo
2
4.6
4.9
5.3
Lower Ventura River
2
2.0
2.3
2.6
Lower West Fork San Gabriel River
1
0.5
0.5
0.5
Matilija Creek
1
3.0
3.0
3.0
Medea Creek
12
3.8
10.6
37.1
Mugu Lagoon
1
58.9
58.9
58.9
North Fork San Gabriel River
1
0.6
0.6
0.6
Pole Creek-Santa Clara River
1
4.0
4.0
4.0
C-ll
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
(Hg/L)
Maximum
Se
(Hg/L)
Salt Canyon-Santa Clara River
7
1.5
4.6
7.5
San Antonio Creek
1
3.6
3.6
3.6
San Francisquito Canyon
2
0.8
0.9
0.9
Santa Fe Flood Control Basin-San Gabriel River
1
0.3
0.3
0.3
Santa Monica Beach-Frontal Santa Monica Bay
1
1.6
1.6
1.6
Santa Paula Creek
1
2.3
2.3
2.3
Snowy Creek-Piru Creek
1
0.9
0.9
0.9
Solstice Canyon-Frontal Santa Monica Bay
2
4.3
4.9
5.4
South Fork Santa Clara River
1
5.6
5.6
5.6
Timber Canyon-Santa Clara River
1
2.3
2.3
2.3
Tujunga Wash-Los Angeles River
2
0.8
3.9
7.0
Tule Creek-Sespe Creek
5
0.6
1.1
1.8
Upper Bouquet Canyon
1
1.0
1.0
1.0
Upper Conejo Arroyo
1
5.8
5.8
5.8
Upper Simi Arroyo
1
8.0
8.0
8.0
Upper Ventura River
1
1.4
1.4
1.4
Verdugo Wash
1
5.3
5.3
5.3
Zuma Canyon-Frontal Pacific Ocean
1
1.8
1.8
1.8
North Coast Regional Board (1 HUC12 Site)
8
0.8
3.1
9.3
Lower Santa Rosa Creek
8
0.8
3.1
9.3
San Diego Regional Board (48 HUC12 Sites)
123
0.2
10.4
250
Aliso Creek
2
10.4
13.9
17.3
Arroyo Trabuco
1
11.3
11.3
11.3
Bee Canyon-Cottonwood Creek
2
6.3
6.9
7.5
Boden Canyon-Santa Ysabel Creek
1
1.7
1.7
1.7
Boulder Creek
3
0.8
1.2
1.8
Buena Vista Creek
1
5.8
5.8
5.8
Cedar Creek
1
1.5
1.5
1.5
Conejos Creek
2
1.2
1.2
1.3
Dan Price Creek-Santa Ysabel Creek
1
0.9
0.9
0.9
El Capitan Reservoir-San Diego River
4
0.7
(4.2)
(12.4)
Forester Creek
7
5.0
8.4
21.3
Guajome Lake-San Luis Rey River
3
(2.4)
(8.0)
(16.0)
Hellers Bend-San Luis Rey River
3
3.2
6.4
11.5
Keys Creek
3
3.5
9.0
18.5
La Posta Creek
4
0.3
2.2
3.6
C-12
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
(Hg/L)
Maximum
Se
(Hg/L)
Los Coches Creek-San Diego River
3
2.4
9.4
17.4
Los Penasquitos Creek
1
7.4
7.4
7.4
Loveland Reservoir-Sweetwater River
2
(2.3)
(5.0)
(7.7)
Lower Escondido Creek
3
4.5
5.4
7.4
Lower Otay Reservoir
2
(3.2)
(3.3)
(3.4)
Lower Pine Valley Creek
1
1.0
1.0
1.0
Lower San Juan Creek
5
1.7
7.2
14.9
Lower Tecate Creek
4
5.1
10.5
14.5
McAlmond Canyon-Cottonwood Creek
1
1.7
1.7
1.7
Middle Pine Valley Creek
3
1.7
2.2
2.6
Middle San Mateo Creek
4
0.8
1.3
2.4
Mission Valley-San Diego River
3
2.6
12.0
18.5
Moosa Canyon
3
1.8
5.8
12.3
Morena Reservoir-Cottonwood Creek
1
(5.4)
(5.4)
(5.4)
Murray Reservoir
3
(6.1)
(14.4)
(26.8)
O'Neill Lake-Santa Margarita River
1
(2.0)
(2.0)
(2.0)
Paradise Creek-San Luis Rey River
4
0.8
2.4
4.4
Prima Deshecha Canada-Frontal Capistrano Bight
1
25.2
25.2
25.2
Rainbow Creek-Santa Margarita River
4
1.8
2.6
3.9
Rice Canyon-Sweetwater River
4
12.5
34.9
43.6
Ritchie Creek-San Diego River
2
0.9
1.3
1.7
Salt Creek-Frontal Gulf of Santa Catalina
1
8.4
8.4
8.4
San Diego Bay
8
7.7
63.4
250
San Marcos Creek
1
3.8
3.8
3.8
San Pasqual Valley-Santa Ysabel Creek
1
5.3
5.3
5.3
Sandia Canyon
1
5.1
5.1
5.1
Tijuana River-Frontal Pacific Ocean
2
9.9
11.0
12.1
Upper Pine Valley Creek
2
1.3
1.7
2.2
Upper San Juan Creek
3
0.8
1.6
2.4
Upper San Mateo Creek
2
1.2
1.3
1.4
Upper San Vicente Creek
3
2.2
4.9
9.9
Viejas Creek-Sweetwater River
3
2.6
8.4
19.7
West Fork San Luis Rey River
3
0.2
1.0
1.6
San Francisco Bay Regional Board (10 HUC12
Sites)
57
0.03
1.2
5.1
Bolinas Lagoon
6
0.5
1.3
2.3
Calabazas Creek-Frontal San Francisco Bay Estuaries
2
0.3
0.3
0.3
Cerrito Creek-Frontal San Francisco Bay Estuaries
12
0.9
1.7
2.6
C-13
-------
California Regional Board Sampling Sites (HUC12)
Number
of
Samples
Minimum
Se
Qig/L)
Mean
Se
Qig/L)
Maximum
Se
Qig/L)
Guadalupe River
3
0.8
1.0
1.3
Lobos Creek-Frontal San Francisco Bay Estuaries
3
0.6
1.5
2.7
Lower Arroyo Mocho
3
0.7
1.4
2.1
San Leandro Creek
4
0.1
0.1
0.2
Sausal Creek-Frontal San Francisco Bay Estuaries
12
1.0
2.2
5.1
Walnut Creek-Frontal Suisun Bay Estuaries
6
0.1
0.3
0.5
Ward Creek-Frontal San Francisco Bay Estuaries
6
0.03
0.1
0.1
Santa Ana Regional Board (8 HUC12 Sites)
16
0.2
13.1
44.7
Lower San Diego Creek
8
0.8
25.2
44.7
Moreno Valley
1
0.5
0.5
0.5
North Fork San Jacinto River
1
0.2
0.2
0.2
San Antonio Canyon
2
0.2
0.3
0.4
San Timoteo Canyon-San Timoteo Wash
1
0.5
0.5
0.5
Strawberry Creek-San Jacinto River
1
0.2
0.2
0.2
Upper Cliino Creek
1
3.0
3.0
3.0
Upper San Diego Creek
1
2.8
2.8
2.8
Grand Total (171 HUC Sites)
710
Data Source: California Environmental Data Exchange Network (CEDEN).
Data includes reported Dissolved Se in water samples collected from October 5, 2004 to June 3, 2014.
CEDEN was last accessed on February 4, 2015.
San Francisco Bay Regional Board summary excludes San Francisco Bay selenium data, since this is a
separate rulemaking effort.
Bolded sampling sites indicate a lentic system (lakes and reservoirs).
Bolded numbers in parenthesis indicate that dissolved selenium exceeded 1.5 |ig Se/L
in lentic systems.
Bolded numbers indicate that dissolved selenium exceeded 3.1 |ig Se/L
in lotic systems.
NA is not available.
HUC12 is Hydrologic Unit Code 12. The HUC12 designation is the name of sampling site.
C-14
-------
Selenium Concentrations in California Water Bodies for Comparison
The EPA final default water column dissolved selenium criterion elements (1.5 |ig/L for
lentic and 3.1 |ig/L for lotic systems) are discussed next as they relate to recently reported
selenium concentrations and distributions in California water bodies. The EPA's level of
confidence in the environmental data is high because the CEDEN database from which the data
were derived for this analysis is the most comprehensive and largest source of selenium
environmental monitoring data collected in California. A summary report of the selenium
concentrations and distributions in California water bodies is provided in Table C-l and Table
C-2 above.
Figure C-l maps the distributions and abundances of the reported total selenium
concentrations (|ig/L) in California surface water samples collected from October 5, 2004
through June 3, 2014. In addition to the reported total selenium concentrations, dissolved
selenium concentrations in California surface water samples were also reported over the same
10-year period (CEDEN 2015). Figure C-2 maps the distributions and abundances of the
reported dissolved selenium concentrations (|ig/L) in surface water samples.
C-15
-------
Carson
City
icramento
Las
Vegas
Total Selenium (ng/L) range in
CA Surface Waters (2004-2014)
O Jo-ihua Ti<
National
©
Figure C-l. Distributions and abundances of total selenium concentrations (fig/L) in
surface water samples collected from October 5, 2004 through June 3, 2014.
The environmental data was last accessed through the California Environmental Data Exchange
Network website (CEDEN: http://www.ceden.org/) on February 4, 2015.
C-l 6
-------
Dissolved Selenium (ng/l) range
in CA Surface Waters (2004-2014)
10.01 - 250.00
O 3.01 - 10.00
O 1.01-3.00
O 0.01 - 1.00
op*
Los
San Fran
San
Vegas
Figure C-2. Distributions and abundances of dissolved selenium concentrations (jig/L) in
surface water samples collected from October 5, 2004 through June 3, 2014.
The environmental data was last accessed through the California Environmental Data Exchange
Network website (CEDEN: http://www.ceden.org/) on February 4, 2015.
C-17
-------
The total selenium concentration distribution was further characterized by sampling site
location in its respective California Regional Water Quality Control Board (Regional Board) area
and results are summarized in Table C-3. The Regional Board areas where the mean total
selenium concentration exceeded 3.1 |ig/L included Central Valley, Central Coast, Los Angeles,
and San Diego. The dissolved selenium concentration distribution was also characterized by
Regional Board area and is summarized in Table C-4. The Regional Board areas where the mean
dissolved selenium concentration exceeded 3.1 |ig/L included Colorado River, Los Angeles, San
Diego, and Santa Ana.
Table C-3. Total Selenium Concentrations by Regional Board Area.
Number of
Number of
Minimum
Mean
Maximum
Regional Board
HUC12 Sites
Samples
Se (ng/L)
Se (ng/L)
Se (ng/L)
1 North Coast
56
352
0.1
1.0
126
2 San Francisco
Bay
7
99
0.03
1.3
4.8
3 Central Coast
6
8
1.6
6.9
14.6
4 Los Angeles
45
116
0.4
16.4
335
5 Central Valley
114
10,637
0.01
12.8
1591
6 Lahontan
2
18
0.2
0.6
1.9
7 Colorado River
NA
NA
NA
NA
NA
8 Santa Ana
10
12
0.1
1.2
5.1
9 San Diego
30
53
0.6
4.5
24.1
Grand Total
270
11,290
Data Source: California Environmental Data Exchange Network (CEDEN).
Data includes reported Total Se concentrations (|ig/L) in water samples collected from
October 5, 2004 to June 3, 2014.
CEDEN was last accessed on February 4, 2015.
San Francisco Bay Regional Board summary excludes data from within the San
Francisco Bay.
NA is not available.
HUC12 is Hydrologic Unit Code 12.
C-18
-------
Table C-4. Dissolved Selenium Concentrations by Regional Board Area.
Number of Number of Minimum Mean Maximum
Regional Board HUC12 Sites Samples Se (^ig/L) Se (^ig/L) Se (^ig/L)
1 North Coast
1
8
0.8
3.1
9.3
2 San Francisco Bay
10
57
0.03
1.2
5.1
3 Central Coast
NA
NA
NA
NA
NA
4 Los Angeles
48
109
0.3
9.1
129
5 Central Valley
38
178
0.01
2.7
106
6 Lahontan
2
18
0.3
0.5
1.4
7 Colorado River
16
201
0.03
6.1
46
8 Santa Ana
8
16
0.2
13.1
45
9 San Diego
48
123
0.2
10.4
250
Grand Total
171
710
Data Source: California Environmental Data Exchange Network (CEDEN).
Data includes reported Dissolved Se concentrations (|ig/L) in water samples collected from
October 5, 2004 to June 3, 2014.
CEDEN was last accessed on February 4, 2015.
San Francisco Bay Regional Board summary excludes data from within the San Francisco
Bay.
NA is not available.
HUC12 is Hydrologic Unit Code 12.
C-19
-------
Appendix D Comparison of Measured and Paired Bird and Fish
Tissue Selenium Concentrations Relative to Their
Respective Tissue Criteria
In 2016, the U.S. EPA published a national freshwater selenium aquatic life criterion
(ALC) including elements for fish tissue of 15.1 mg Se/kg dw for eggs and ovaries, 8.5 mg Se/kg
dw for whole body, and 11.3 mg Se/kg dw for muscle (U.S. EPA 2016a). The current document
presents a final aquatic-dependent wildlife selenium criterion of 11.2 mg Se/kg dw for bird eggs
for the State of California. Of interest is information regarding whether the fish tissue criterion
elements would be protective of birds, and/or whether the bird criterion element would be
protective of fish.
In this analysis measured bird and fish tissue selenium concentrations were used to
indicate if one criterion element would be protective of the other. Paired fish and bird tissue data
were obtained from ten USGS reconnaissance studies conducted throughout the Western United
States, and four reports of monitoring results in the Newport Bay, CA watershed. Collectively,
these studies encompass a range of regions across the Western United States, many of which
were associated with irrigation projects. An initial literature search was conducted to find
supplemental data from eastern states. While these supplemental data from eastern states appear
to be much more limited, additional bird and fish data from West Virginia were obtained from
West Virginia Department of Environmental Protection (WVDEP 2010, 2019). However, these
data were not included in the current analysis because the bird eggs were collected just over one
year before the fish tissue samples were collected, and therefore did not meet the data inclusion
criteria detailed below.
For purposes of this comparison, data were considered paired if they were collected at the
same site (as identified by the respective study authors) within one year of each other.
Additionally, only bird species considered to be aquatic-dependent, defined here as species that
depend on aquatic prey (e.g., fish and emergent aquatic insects) as a major food source, were
included in this analysis (e.g., members of the order Galliformes such as chickens, ring-necked
pheasant or Northern bobwhite were excluded from this analysis). Sites were classified as lentic
or lotic based on site descriptions provided by the study authors. Fish and bird tissue selenium
concentrations were recorded for every unique bird-fish species pair at each site. When multiple
selenium measurements for a particular bird or fish species were available for a given pairing,
D-l
-------
the final species level concentration was calculated as the geometric mean for all available
measurements.
Selenium in birds was always expressed as concentrations in bird eggs. Selenium in fish
was expressed as both whole body and egg-ovary concentrations. The majority (> 95%) of fish
samples were reported for whole body and converted to egg-ovary concentrations using
appropriate egg-ovary to whole body conversion factors for that species following the
hierarchical approach based on taxonomic relatedness described in the EPA's 2016 selenium
ALC(U.S. EPA 2016a).
When muscle and/or egg-ovary measurements were available at a particular site,
appropriate conversion factors, following procedures described above, were applied to convert
all measured selenium concentrations to whole body (Figure D-l). This process was then
repeated to convert all selenium concentrations to egg-ovary (Figure D-2). For example, if a
sample was expressed as a muscle concentration, it was converted to whole body using a muscle
to whole body conversion factor, and then separately converted to egg-ovary using a muscle to
egg-ovary conversion factor. The objective of this procedure was to minimize uncertainty
associated with the application of two conversion factors to the same sample. As noted above,
once all fish measurements at a given site were converted to a single tissue type, the final
concentration was calculated as the geometric mean for all available measurements.
Paired selenium concentrations in bird eggs and fish tissue for all waterbodies are
reported in Figure D-l (fish whole body - bird egg) and Figure D-2 (fish egg-ovary - bird egg).
In each figure, selenium concentrations in fish are plotted along the x-axis and selenium
concentrations in birds are plotted along the y-axis. Dashed lines represent the bird (horizontal)
and fish (vertical) tissue criterion element concentrations. Bird egg concentrations below the
horizontal line meet the bird criterion and those above the line exceed the criterion. Fish tissue
concentrations to the left of the line meet the criterion and to the right of the line exceed the
criterion. The four quadrants created by these dashed lines show the comparative protectiveness
of the bird and fish tissue criteria, based on the numbers of points within each quadrant. For
example, points in the lower left represent data pairs that meet both the bird and fish criteria.
Points in the upper right exceed both the bird and fish criteria. Points in the upper left meet the
fish criterion but exceed the bird criterion, and finally, points in the lower right meet the bird
criterion but exceed the fish criterion.
D-2
-------
is
"S
DC
DC
DC
1
£
128
64
32
16
8
4
2
1
0.5
0.25
M
it
i
a
*1
»*
SIS1
1
»
A a
a
<
«
*3
Spf
1
V
8 #1
» 9
a A
V w
0.25
0.5
2 4 8 16
Fish Whole Body mg Se/kg dw
32
64
128
Figure D-l. Selenium concentrations in paired bird egg and fish whole body tissue samples
throughout the Western U.S.
The horizontal line is the final bird egg criterion of 11.2 mg Se/kg dw. The vertical line is the
whole body fish tissue criterion element of 8.5 mg Se/kg dw (U.S. EPA 2016a). Points in the
points in the lower left represent data pairs that meet both the bird and fish criteria. Points in the
upper right exceed both the bird and fish criteria. Points in the upper left meet the fish criteria but
exceed the bird criterion. Points in the lower right meet the bird criterion but exceed the fish
criterion. Each point represents the geometric mean selenium concentrations measured in a
unique bird - fish species combination at the same site within one year. Fish tissues not
measured as whole body converted using conversion factors based on taxonomic relatedness
following the 2016 freshwater selenium criterion document (U.S. EPA 2016a).
D-3
-------
if
T5
cn
W)
&£
DC
Ol
¦E
£
128
64
32
16
8
4
2
1
0.5
0.25
**
M
j.i
«
1-1-
\9f
r *
?.\i
mt
r *
a
i'-V
w
1
!*»'
U
m ww m w
w
0.25 0.5 1 2 4 8 16 32 64 128
Fish Egg-Ovary mg Se/kg dw
Figure D-2. Selenium concentrations in paired bird egg and fish egg-ovary tissue samples
throughout the Western U.S.
The horizontal line is the final bird egg criterion of 11.2 mg Se/kg dw. The vertical line is the
egg-ovary fish tissue criterion element of 15.1 mg Se/kg dw (U.S. EPA 2016a). Points in the
points in the lower left represent data pairs that meet both the bird and fish criteria. Points in the
upper right exceed both the bird and fish criteria. Points in the upper left meet the fish criterion
but exceed the bird criterion. Points in the lower right meet the bird criterion but exceed the fish
criterion. Each point represents the geometric mean selenium concentrations measured in a
unique bird - fish species combination at the same site within one year. Fish tissues not
measured as egg-ovary converted using conversion factors based on taxonomic relatedness
following the 2016 freshwater selenium criterion document (U.S. EPA 2016a).
The number of values in the lower right quadrant of both figures is much larger than the
number of values in the upper left quadrant, meaning that for these data, the fish criterion should
be protective of birds (in fact, there was only one site-species pair in the upper left quadrant), but
the bird criterion will not necessarily be protective of fish. There were virtually no differences in
the relative proportions of points between the two fish tissue types (Table D-l). This is not
surprising, as nearly all fish samples were based on whole body measurements, and the fish egg-
ovary concentrations primarily reflect whole body concentrations converted to egg-ovary
concentrations. Unreported data from West Virginia described above were consistent with
D-4
-------
reported data, in that for all available WV species pairs, either birds and fish both attained, or
bird eggs attained but fish tissue did not attain (WVDEP 2010, 2019). Paired site and species
level selenium concentrations in bird and fish tissue are reported in Table D-2.
Table D-l. Counts and Relative Proportions of Whether Paired Selenium Measurements in
Bird Eggs and Fish Whole-Body or Egg-Ovary Tissues Met or Exceeded Their Respective
Criterion.
Each pair is a unique bird-fish species combination sampled at the same location within one year.
Comparison
Condition
Counts
Proportions
All
Sites
Lentic
Lotic
All
Sites
Lentic
Lotic
Fish Whole
Body - Bird
Egg
Total Pairs
287
198
89
1.000
1.000
1.000
Bird and fish attain
159
91
68
0.554
0.460
0.764
Bird attains, fish does not
attain
93
78
15
0.324
0.394
0.169
Fish attains, bird does not
attain
1
1
0
0.003
0.005
0.000
Neither bird nor fish attain
34
28
6
0.118
0.141
0.067
Fish Egg-
Ovary - Bird
Egg
Total Pairs
287
198
89
1.000
1.000
1.000
Bird and fish attain
161
93
68
0.561
0.470
0.764
Bird attains, fish does not
attain
91
76
15
0.317
0.384
0.169
Fish attains, bird does not
attain
1
1
0
0.003
0.005
0.000
Neither bird nor fish attain
34
28
6
0.118
0.141
0.067
Paired selenium concentrations in bird eggs and fish tissue for lentic waterbodies are
reported in Figure D-3 (fish whole body - bird egg) and Figure D-4 (fish egg-ovary - bird egg).
The relative distributions of points in these figures are qualitatively similar to the distributions in
the figures representing all waterbodies, as lentic waterbodies comprise nearly 70% of the sites
with paired data. Overall, the proportion of lentic sites where both birds and fish meet their
respective criteria is slightly lower than for all sites, and the proportion of lentic sites where birds
meet the bird criterion but fish do not meet the fish criterion is slightly higher than for all sites
(Table D-l).
D-5
-------
128
64
32
if
rs
16
M
8
60
s
4
ei
4i
H
2
s
1
0.5
0.25
«T
it
**ir
«i
1
#.
A A
1 4Hf
9 w
P
»
0.25
0.5
2 4 8 16
Fish Whole Body mg Se/kg d\v
32
64
128
Figure D-3. Selenium concentrations in paired bird egg and fish whole body tissue samples
from lentic sites throughout the Western U.S.
The horizontal line is the final bird egg criterion of 11.2 mg Se/kg dw. The vertical line is the
whole body fish tissue criterion element of 8.5 mg Se/kg dw (U.S. EPA 2016a). Points in the
points in the lower left represent data pairs that meet both the bird and fish criteria. Points in the
upper right exceed both the bird and fish criteria. Points in the upper left meet the fish criteria but
exceed the bird criterion. Points in the lower right meet the bird criterion but exceed the fish
criterion. Each point represents the geometric mean selenium concentrations measured in a
unique bird - fish species combination at the same site within one year. Fish tissues not
measured as whole body converted using conversion factors based on taxonomic relatedness
following the 2016 freshwater selenium criterion document (U.S. EPA 2016a).
D-6
-------
128
64
32
if
16
cn
8
W)
S
60
4
tt
Ol
TS
-
2
PQ
0.5
0.25
i
i
i
i
i
1 M
7 T
.
i «
V
*
I-
«
A
4 "5
i-1
m mm
»
w
1
r* a*
1
1
1
1
1
1
0.25 0.5 1 2 4 8 16 32 64 128
Fish Egg-Ovary mg Se/kg dw
Figure D-4. Selenium concentrations in paired bird egg and fish egg-ovary tissue samples
from lentic sites throughout the Western U.S.
The horizontal line is the final bird egg criterion of 11.2 mg Se/kg dw. The vertical line is the
egg-ovary fish tissue criterion element of 15.1 mg Se/kg dw (U.S. EPA 2016a). Points in the
points in the lower left represent data pairs that meet both the bird and fish criteria. Points in the
upper right exceed both the bird and fish criteria. Points in the upper left meet the fish criterion
but exceed the bird criterion. Points in the lower right meet the bird criterion but exceed the fish
criterion. Each point represents the geometric mean selenium concentrations measured in a
unique bird - fish species combination at the same site within one year. Fish tissues not
measured as egg-ovary converted using conversion factors based on taxonomic relatedness
following the 2016 freshwater selenium criterion document (U.S. EPA 2016a).
Finally, paired selenium concentrations in bird eggs and fish tissue for lentic waterbodies
are reported in Figure D-5 (fish whole body - bird egg) and Figure D-6 (fish egg-ovary - bird
egg). Overall, the proportion of lotic sites where both birds and fish meet their respective criteria
is higher than for all sites. It is unclear whether these lentic-lotic differences represent a general
result or are unique to these studies. Despite these differences, however, the general result that
the bird egg criterion will most likely be met so long as the fish tissue criterion is being met, but
the fish tissue criterion will not necessarily be met if the bird criterion is met, applies to both
lentic and lotic waterbodies.
D-7
-------
I
t
"53
DC
BC
DC
01
"H
128
64
32
16
8
4
2
1
0.5
0.25
*,
) #
m J m
A
»*
«
.is:
4
tv
*
m
I
a a
W W
0.25 0.5 1 2 4 8 16
Fish Whole Body mg Se/kg dw
32
64
128
Figure D-5. Selenium concentrations in paired bird egg and fish whole body tissue samples
from lotic sites throughout the Western U.S.
The horizontal line is the final bird egg criterion of 11.2 mg Se/kg dw. The vertical line is the
whole body fish tissue criterion element of 8.5 mg Se/kg dw (U.S. EPA 2016a). Points in the
points in the lower left represent data pairs that meet both the bird and fish criteria. Points in the
upper right exceed both the bird and fish criteria. Points in the upper left meet the fish criteria but
exceed the bird criterion. Points in the lower right meet the bird criterion but exceed the fish
criterion. Each point represents the geometric mean selenium concentrations measured in a
unique bird - fish species combination at the same site within one year. Fish tissues not
measured as whole body converted using conversion factors based on taxonomic relatedness
following the 2016 freshwater selenium criterion document (U.S. EPA 2016a).
D-8
-------
I
t
"53
DC
BC
DC
01
"H
128
64
32
16
8
4
2
1
0.5
0.25
4
) 0
> .
m\U
1
«
:*«
.
1
m
I
0.25
0.5
2 4 8 16
Fish Egg-Ovary mg Se/kg dw
32
64
128
Figure D-6. Selenium concentrations in paired bird egg and fish egg-ovary tissue samples
from lotic sites throughout the Western U.S.
The horizontal line is the final bird egg criterion of 11.2 mg Se/kg dw. The vertical line is the
egg-ovary fish tissue criterion element of 15.1 mg Se/kg dw (U.S. EPA 2016a). Points in the
points in the lower left represent data pairs that meet both the bird and fish criteria. Points in the
upper right exceed both the bird and fish criteria. Points in the upper left meet the fish criterion
but exceed the bird criterion. Points in the lower right meet the bird criterion but exceed the fish
criterion. Each point represents the geometric mean selenium concentrations measured in a
unique bird - fish species combination at the same site within one year. Fish tissues not
measured as egg-ovary converted using conversion factors based on taxonomic relatedness
following the 2016 freshwater selenium criterion document (U.S. EPA 2016a).
D-9
-------
Table D-2. Bird and Fish Tissue Species Level Average Selenium Concentrations (mg Se/kg
dw).
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Butler et al.
1991
Sweitzer Lake
lentic
American
coot
11.10
Butler et al.
1991
Sweitzer Lake
lentic
red-winged
blackbird
17.60
Butler et al.
1991
Sweitzer Lake
lentic
yellow-
headed
blackbird
9.59
Butler et al.
1991
Sweitzer Lake
lentic
black
bullhead
39.00
56.55
Butler et al.
1991
Sweitzer Lake
lentic
carp
35.56
69.35
Butler et al.
1991
Sweitzer Lake
lentic
channel
catfish
24.10
34.95
Butler et al.
1991
Sweitzer Lake
lentic
flannelmouth
sucker
22.00
31.02
Butler et al.
1991
Sweitzer Lake
lentic
green sunfish
19.53
28.32
Butler et al.
1991
Sweitzer Lake
lentic
white sucker
39.00
53.82
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
mallard
5.90
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
Canada
goose
3.04
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
red-winged
blackbird
8.35
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
brown trout
2.00
2.90
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
green sunfish
7.90
11.46
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
roundtail
chub
1.90
3.93
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
carp
10.30
20.09
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
fathead
minnow
8.10
11.34
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
speckled
dace
4.80
9.36
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
flannelmouth
sucker
2.50
3.53
D-10
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Butler et al.
1991
Gunnison River at Escalante
State Wildlife Area
lotic
mottled
sculpin
5.00
7.25
Butler et al.
1993
Los Pinos River at La Boca
lotic
American
bittern
5.30
Butler et al.
1993
Los Pinos River at La Boca
lotic
mallard
3.65
Butler et al.
1993
Los Pinos River at La Boca
lotic
red-winged
blackbird
2.93
Butler et al.
1993
Los Pinos River at La Boca
lotic
yellow-
headed
blackbird
3.69
Butler et al.
1993
Los Pinos River at La Boca
lotic
brown trout
1.80
2.61
Butler et al.
1993
Los Pinos River at La Boca
lotic
channel
catfish
2.34
3.06
Butler et al.
1993
Los Pinos River at La Boca
lotic
flannelmouth
sucker
2.50
3.52
Butler et al.
1993
Los Pinos River at La Boca
lotic
speckled
dace
8.70
16.97
Butler et al.
1993
Los Pinos River at La Boca
lotic
white sucker
2.80
3.86
Butler et al.
1993
Los Pinos River at La Boca
lotic
mallard
3.43
Butler et al.
1993
Los Pinos River at La Boca
lotic
yellow-
headed
blackbird
4.47
Butler et al.
1993
Los Pinos River at La Boca
lotic
fathead
minnow
11.00
15.40
Butler et al.
1993
Los Pinos River at La Boca
lotic
speckled
dace
8.50
16.58
Butler et al.
1993
Los Pinos River at La Boca
lotic
white sucker
9.50
13.11
Butler et al.
1993
Rock Creek on the Oxford
Tract, near Oxford
lotic
mallard
3.43
Butler et al.
1993
Rock Creek on the Oxford
Tract, near Oxford
lotic
yellow-
headed
blackbird
4.47
Butler et al.
1993
Rock Creek on the Oxford
Tract, near Oxford
lotic
fathead
minnow
11.00
15.40
Butler et al.
1993
Rock Creek on the Oxford
Tract, near Oxford
lotic
speckled
dace
8.50
16.58
Butler et al.
Rock Creek on the Oxford
lotic
white sucker
9.50
13.11
D-ll
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
1993
Tract, near Oxford
Butler et al.
1994
Brozina Pond near F and
2100 Roads, east of Delta
lentic
American
avocet
41.84
Butler et al.
1994
Brozina Pond near F and
2100 Roads, east of Delta
lentic
fathead
minnow
54.85
76.80
Butler et al.
1994
Brozina Pond near F and
2100 Roads, east of Delta
lentic
green sunfish
55.00
79.75
Butler et al.
1994
Frontgrowers pond
lentic
American
coot
11.20
Butler et al.
1994
Frontgrowers pond
lentic
pied-billed
grebe
13.00
Butler et al.
1994
Frontgrowers pond
lentic
red-winged
blackbird
4.10
Butler et al.
1994
Frontgrowers pond
lentic
Western
grebe
11.32
Butler et al.
1994
Frontgrowers pond
lentic
yellow-
headed
blackbird
7.65
Butler et al.
1994
Frontgrowers pond
lentic
common
carp
14.49
27.82
Butler et al.
1994
Ferriers Pond near Austin
lentic
Canada
goose
19.00
Butler et al.
1994
Ferriers Pond near Austin
lentic
American
coot
20.44
Butler et al.
1994
Ferriers Pond near Austin
lentic
yellow-
headed
blackbird
14.33
Butler et al.
1994
Ferriers Pond near Austin
lentic
fathead
minnow
69.28
96.99
Butler et al.
1994
Gretts Pond near Olathe
lentic
American
coot
7.20
Butler et al.
1994
Gretts Pond near Olathe
lentic
yellow-
headed
blackbird
11.40
Butler et al.
1994
Gretts Pond near Olathe
lentic
fathead
minnow
36.00
50.40
Butler et al.
1994
Markley Pond on East Mesa,
southeast of Olathe
lentic
mallard
9.50
Butler et al.
1994
Markley Pond on East Mesa,
southeast of Olathe
lentic
red-winged
blackbird
10.49
Butler et al.
1994
Markley Pond on East Mesa,
southeast of Olathe
lentic
yellow-
headed
12.48
D-12
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
blackbird
Butler et al.
1994
Markley Pond on East Mesa,
southeast of Olathe
lentic
fathead
minnow
51.00
71.40
Butler et al.
1994
East Branch of Reed Wash at
M Road
lotic
mallard
8.95
Butler et al.
1994
East Branch of Reed Wash at
M Road
lotic
red-winged
blackbird
4.60
Butler et al.
1994
East Branch of Reed Wash at
M Road
lotic
flannelmouth
sucker
13.00
18.33
Butler et al.
1994
St. George Pond near Austin
lentic
red-winged
blackbird
18.00
Butler et al.
1994
St. George Pond near Austin
lentic
fathead
minnow
88.99
124.59
Butler et al.
1994
Thompsons Pond near 12
and 0 Roads, near Mack
lentic
American
avocet
7.20
Butler et al.
1994
Thompsons Pond near 12
and 0 Roads, near Mack
lentic
green sunfish
13.00
18.85
Butler et al.
1995
Dawson Draw near Lewis
lotic
red-winged
blackbird
1.60
Butler et al.
1995
Dawson Draw near Lewis
lotic
bluehead
sucker
0.90
1.64
Butler et al.
1995
Dawson Draw near Lewis
lotic
fathead
minnow
3.63
5.08
Butler et al.
1995
Dawson Draw near Lewis
lotic
speckled
dace
5.29
10.31
Butler et al.
1995
Totten Reservoir
lentic
American
coot
1.62
Butler et al.
1995
Totten Reservoir
lentic
mallard
2.41
Butler et al.
1995
Totten Reservoir
lentic
yellow-
headed
blackbird
3.73
Butler et al.
1995
Totten Reservoir
lentic
black crappie
2.50
3.63
Butler et al.
1995
Totten Reservoir
lentic
bluegill
2.30
4.90
Butler et al.
1995
Totten Reservoir
lentic
channel
catfish
1.00
1.45
Butler et al.
1995
Totten Reservoir
lentic
northern pike
2.00
3.43
Butler et al.
1995
Totten Reservoir
lentic
walleye
1.75
2.56
D-13
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Butler et al.
1995
Totten Reservoir
lentic
yellow perch
1.65
2.39
Butler et al.
1997
Large pond south of G Road,
southern Mancos Valley
lentic
yellow-
headed
blackbird
5.20
Butler et al.
1997
Large pond south of G Road,
southern Mancos Valley
lentic
American
coot
6.88
Butler et al.
1997
Large pond south of G Road,
southern Mancos Valley
lentic
cinnamon
teal
11.00
Butler et al.
1997
Large pond south of G Road,
southern Mancos Valley
lentic
ruddy duck
9.13
Butler et al.
1997
Large pond south of G Road,
southern Mancos Valley
lentic
yellow-
headed
blackbird
5.20
Butler et al.
1997
Large pond south of G Road,
southern Mancos Valley
lentic
fathead
minnow
11.00
15.40
Butler et al.
1997
Pond on Woods Canyon at
15 Road
lentic
red-winged
blackbird
2.63
Butler et al.
1997
Pond on Woods Canyon at
15 Road
lentic
fathead
minnow
17.15
1.40
Byron and
Santolo 2014
Big canyon wash
lotic
American
coot
43.00
Byron and
Santolo 2014
Big canyon wash
lotic
pied-billed
grebe
15.00
Byron and
Santolo 2014
Big canyon wash
lotic
mosquitofish
52.49
62.99
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
American
avocet
6.03
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
bluegill
13.42
28.59
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
carp
17.80
34.71
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
fathead
minnow
17.20
24.08
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
largemouth
bass
11.12
15.80
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
mosquitofish
14.00
16.80
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
inland
silverside
10.75
15.59
Byron and
Santolo 2014
Irvine Ranch Water District
Marsh
lentic
threadfin
shad
10.40
15.08
D-14
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Byron and
Santolo 2014
UC Irvine Marsh
lentic
black-necked
stilt
5.60
Byron and
Santolo 2014
UC Irvine Marsh
lentic
pied-billed
grebe
4.35
Byron and
Santolo 2014
UC Irvine Marsh
lentic
American
coot
2.19
Byron and
Santolo 2014
UC Irvine Marsh
lentic
mosquitofish
5.70
6.84
Byron et al.
2010
Big canyon wash
lotic
pied-billed
grebe
36.78
Byron et al.
2010
Big canyon wash
lotic
mosquitofish
61.30
73.56
Byron et al.
2010
Irvine Ranch Water District
Marsh
lentic
American
avocet
11.59
Byron et al.
2010
Irvine Ranch Water District
Marsh
lentic
black
skimmer
3.82
Byron et al.
2010
Irvine Ranch Water District
Marsh
lentic
largemouth
bass
16.50
23.43
Byron et al.
2010
Irvine Ranch Water District
Marsh
lentic
green sunfish
18.90
27.41
Byron et al.
2010
San Diego Cr.
lotic
American
avocet
11.40
Byron et al.
2010
San Diego Cr.
lotic
black-necked
stilt
14.49
Byron et al.
2010
San Diego Cr.
lotic
Bluegill
16.16
34.42
Byron et al.
2010
UC Irvine Marsh
lentic
American
coot
6.48
Byron et al.
2010
UC Irvine Marsh
lentic
pied-billed
grebe
9.55
Byron et al.
2010
UC Irvine Marsh
lentic
mosquitofish
5.40
6.48
Byron et al.
2012
Big canyon wash
lotic
pied-billed
grebe
40.00
Byron et al.
2012
Big canyon wash
lotic
mosquitofish
49.74
59.69
Byron et al.
2012
Irvine Ranch Water District
Marsh
lentic
American
avocet
4.66
Byron et al.
2012
Irvine Ranch Water District
Marsh
lentic
black-necked
stilt
3.30
Byron et al.
2012
Irvine Ranch Water District
Marsh
lentic
green sunfish
12.95
18.78
D-15
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Byron et al.
2012
Irvine Ranch Water District
Marsh
lentic
bluegill
14.96
31.87
Byron et al.
2012
Irvine Ranch Water District
Marsh
lentic
largemouth
bass
16.32
23.17
Byron et al.
2012
Irvine Ranch Water District
Marsh
lentic
threadfin
shad
7.11
10.31
Byron et al.
2012
Peters canyon wash
lotic
black-necked
stilt
7.44
Byron et al.
2012
Peters canyon wash
lotic
green sunfish
13.30
19.28
Byron et al.
2012
Peters canyon wash
lotic
red shiner
14.00
27.30
Byron et al.
2012
UC Irvine Marsh
lentic
American
coot
2.20
Byron et al.
2012
UC Irvine Marsh
lentic
American
avocet
6.06
Byron et al.
2012
UC Irvine Marsh
lentic
black-necked
stilt
2.63
Byron et al.
2012
UC Irvine Marsh
lentic
mosquitofish
12.82
15.38
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
American
avocet
5.04
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
black-necked
stilt
6.50
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
largemouth
bass
14.53
20.63
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
bluegill
16.62
34.31
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
threadfin
shad
10.70
15.52
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
red shiner
16.50
32.18
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
redear
sunfish
14.50
25.96
Byron et al.
2013
Irvine Ranch Water District
Marsh
lentic
green sunfish
17.80
25.81
Byron et al.
2013
UC Irvine Marsh
lentic
American
coot
3.20
Byron et al.
2013
UC Irvine Marsh
lentic
catfish
7.45
10.80
Byron et al.
2013
UC Irvine Marsh
lentic
mosquitofish
5.24
6.29
D-16
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Lambing et al.
1994
Priest Butte Lakes
lentic
American
avocet
24.19
Lambing et al.
1994
Priest Butte Lakes
lentic
gadwall
4.00
Lambing et al.
1994
Priest Butte Lakes
lentic
northern
shovel er
6.39
Lambing et al.
1994
Priest Butte Lakes
lentic
black crappie
47.01
68.17
Lambing et al.
1994
Priest Butte Lakes
lentic
brassy
minnow
29.00
56.55
Lambing et al.
1994
Priest Butte Lakes
lentic
brook
stickleback
35.00
50.75
Lambing et al.
1994
Priest Butte Lakes
lentic
carp
26.90
52.45
Lambing et al.
1994
Priest Butte Lakes
lentic
fathead
minnow
25.00
35.00
Lambing et al.
1994
Priest Butte Lakes
lentic
white sucker
27.39
37.80
Lambing et al.
1994
Priest Butte Lakes
lentic
yellow perch
67.00
97.15
Lambing et al.
1994
Pond 3
lentic
American
Avocet
3.17
Lambing et al.
1994
Pond 3
lentic
brook
stickleback
3.30
4.79
Lambing et al.
1994
Pond 5
lentic
American
coot
6.57
Lambing et al.
1994
Pond 5
lentic
eared grebe
13.27
Lambing et al.
1994
Pond 5
lentic
lesser scaup
7.78
Lambing et al.
1994
Pond 5
lentic
northern
shovel er
2.60
Lambing et al.
1994
Pond 5
lentic
redhead
10.62
Lambing et al.
1994
Pond 5
lentic
ruddy duck
8.35
Lambing et al.
1994
Pond 5
lentic
brook
stickleback
6.10
8.85
Lambing et al.
1994
Freezout Lake - north
lentic
American
avocet
4.62
Lambing et al.
1994
Freezout Lake - north
lentic
lesser scaup
8.05
D-17
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Lambing et al.
1994
Freezout Lake - north
lentic
mallard
4.21
Lambing et al.
1994
Freezout Lake - north
lentic
brook
stickleback
17.00
24.65
Lambing et al.
1994
Freezout Lake - south
lentic
American
avocet
5.40
Lambing et al.
1994
Freezout Lake - south
lentic
American
coot
7.21
Lambing et al.
1994
Freezout Lake - south
lentic
eared grebe
13.79
Lambing et al.
1994
Freezout Lake - south
lentic
lesser scaup
9.28
Lambing et al.
1994
Freezout Lake - south
lentic
mallard
5.14
Lambing et al.
1994
Freezout Lake - south
lentic
northern
shovel er
5.99
Lambing et al.
1994
Freezout Lake - south
lentic
ruddy duck
4.33
Lambing et al.
1994
Freezout Lake - south
lentic
fathead
minnow
12.88
18.03
Low and Mullins
1990
Spring Creek
lotic
American
coot
0.5
Low and Mullins
1990
Spring Creek
lotic
mallard
1.3
Low and Mullins
1990
Spring Creek
lotic
Utah sucker
1.4
2.39
Low and Mullins
1990
Spring Creek
lotic
mountain
whitefish
1.7
2.40
Ong et al. 1991
18D - Marsh in SE BDNWR
lentic
American
coot
0.34
Ong et al. 1991
18D - Marsh in SE BDNWR
lentic
carp
1.10
2.15
Ong et al. 1991
18D - Marsh in SE BDNWR
lentic
threadfin
shad
0.78
1.13
Ong et al. 1991
24B - Marsh in SE BDNWR
lentic
mallard
0.95
Ong et al. 1991
24B - Marsh in SE BDNWR
lentic
carp
1.00
1.95
Ong et al. 1991
24B - Marsh in SE BDNWR
lentic
centrarchidae
0.93
1.35
Ong et al. 1991
24B - Marsh in SE BDNWR
lentic
mosquitofish
0.92
1.10
Ong et al. 1991
24B - Marsh in SE BDNWR
lentic
brown
bullhead
1.40
2.03
Ong et al. 1991
24C - Marsh in SE BDNWR
lentic
American
coot
0.75
D-18
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Ong et al. 1991
24C - Marsh in SE BDNWR
lentic
mallard
0.96
Ong et al. 1991
24C - Marsh in SE BDNWR
lentic
carp
0.83
1.62
Ong et al. 1991
24C - Marsh in SE BDNWR
lentic
centrarchidae
0.96
1.39
Ong et al. 1991
24C - Marsh in SE BDNWR
lentic
mosquitofish
0.91
1.09
Ong et al. 1991
24C - Marsh in SE BDNWR
lentic
brown
bullhead
1.70
2.47
Rinella et al
1994
Ft. Boise WMA
lotic
American
avocet
2.93
Rinella et al
1994
Ft. Boise WMA
lotic
American
coot
1.79
Rinella et al
1994
Ft. Boise WMA
lotic
black-necked
stilt
3.95
Rinella et al
1994
Ft. Boise WMA
lotic
cinnamon
teal
1.75
Rinella et al
1994
Ft. Boise WMA
lotic
bullhead
1.47
2.13
Rinella et al
1994
Ft. Boise WMA
lotic
carp
0.97
1.89
Rinella et al
1994
Ft. Boise WMA
lotic
sunfish
1.58
2.29
Rinella et al
1994
Snake River at Weiser
lotic
black-
crowned
night heron
3.28
Rinella et al
1994
Snake River at Weiser
lotic
California
gull
2.76
Rinella et al
1994
Snake River at Weiser
lotic
carp
1.94
3.78
Rinella et al
1994
Snake River at Weiser
lotic
channel
catfish
1.88
2.73
Rinella et al
1994
Snake River at Weiser
lotic
smallmouth
bass
2.44
3.46
Rinella et al
1994
Snake River mouth of Jump
Creek
lotic
mallard
1.84
Rinella et al
1994
Snake River mouth of Jump
Creek
lotic
carp
1.90
3.71
Rinella et al
1994
Snake River mouth of Jump
Creek
lotic
channel
catfish
2.90
4.21
Rinella et al
1994
Snake River mouth of Jump
Creek
lotic
mountain
whitefish
4.50
7.70
Rinella et al
1994
Snake River mouth of Jump
Creek
lotic
smallmouth
bass
3.50
4.97
Rinella and
Harney Lake
lentic
American
1.69
D-19
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Schuler 1992
avocet
Rinella and
Schuler 1992
Harney Lake
lentic
double
crested
cormorant
2.13
Rinella and
Schuler 1992
Harney Lake
lentic
gadwall
1.13
Rinella and
Schuler 1992
Harney Lake
lentic
great blue
heron
2.69
Rinella and
Schuler 1992
Harney Lake
lentic
common
carp
2.20
4.22
Rinella and
Schuler 1992
Harney Lake
lentic
tui chub
3.10
6.42
Rinella and
Schuler 1992
Harney Lake
lentic
white
crappie
2.20
3.19
Rinella and
Schuler 1992
North Malheur Lake
lentic
American
avocet
2.00
Rinella and
Schuler 1992
North Malheur Lake
lentic
American
coot
1.54
Rinella and
Schuler 1992
North Malheur Lake
lentic
double
crested
cormorant
2.39
Rinella and
Schuler 1992
North Malheur Lake
lentic
gadwall
1.37
Rinella and
Schuler 1992
North Malheur Lake
lentic
great blue
heron
2.29
Rinella and
Schuler 1992
North Malheur Lake
lentic
white pelican
2.80
Rinella and
Schuler 1992
North Malheur Lake
lentic
brown
bullhead
2.50
3.63
Rinella and
Schuler 1992
North Malheur Lake
lentic
common
carp
1.90
3.65
Rinella and
Schuler 1992
North Malheur Lake
lentic
white
crappie
1.10
1.60
Rinella and
Schuler 1992
South Malheur Lake
lentic
American
avocet
1.55
Rinella and
Schuler 1992
South Malheur Lake
lentic
American
coot
1.43
Rinella and
Schuler 1992
South Malheur Lake
lentic
gadwall
1.16
Rinella and
Schuler 1992
South Malheur Lake
lentic
brown
bullhead
1.90
2.76
Rinella and
South Malheur Lake
lentic
common
2.00
3.84
D-20
-------
Selenium
(mg Se/kg dw
Reference
Site
Site
Type
Species
Bird
Egg
Fish
WB
Fish
E-O
Schuler 1992
carp
Rinella and
Schuler 1992
South Malheur Lake
lentic
largemouth
bass
0.92
1.31
Rinella and
Schuler 1992
South Malheur Lake
lentic
sucker
1.60
2.26
Rinella and
Schuler 1992
South Malheur Lake
lentic
white
crappie
0.66
0.96
D-21
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Appendix D References
Butler, D.L., R.P. Krueger, B.C. Osmundson, A.L. Thompson and S.K. McCall. 1991.
Reconnaissance investigation of water quality, bottom sediment, and biota associated with
irrigation drainage in the Gunnison and Uncompahgre River basins and at Sweitzer Lake, west-
central Colorado, 1988-89. U.S. Geological Survey Water-Resources Investigations Report No.
91-4103. Denver, CO.
Butler, D.L., R.P. Krueger, B.C. Osmundson and A.L. Thompson. 1993. Reconnaissance
investigation of water quality, bottom sediment, and biota associated with irrigation drainage in
the pine river project area, Southern Ute Indian Reservation, Southwestern Colorado and
Northwestern New Mexico, 1988-9. U.S. Geological Survey Water-Resources Investigations
Report No. 92-4188. Denver, CO.
Butler, D.L., W.G. Wright, D.A. Hahn, R.P. Krueger and B.C. Osmundson. 1994. Physical,
chemical, and biological data for detailed study of irrigation drainage in the Uncompahgre
project area and in the Grand Valley, west-central Colorado, 1991-92. U.S. Geological Survey
Open File Report No. 94-110. Denver, CO.
Butler, D.L., R.P. Krueger, B.C. Osmundson and E.G. Jensen. 1995. Reconnaissance
investigation of water quality, bottom sediment, and biota associated with irrigation drainage in
the Dolores project area, Southwestern Colorado and Southeastern Utah, 1990-91. U.S.
Geological Survey. Water-Resources Investigations Report 94-4041. Denver, CO 1995.
Butler, D.L., B.C. Osmundson, and R.P. Krueger. 1997. Field screening of water, soil, bottom
sediment, and biota associated with irrigation drainage in the Dolores Project and the Mancos
River Basin, Southwestern Colorado, 1994. U.S. Geological Survey. Water-Resources
Investigations Report 97-4008. Denver, Colorado 1997.
Byron, E. and G. Santolo. 2010. 2010 Selenium Monitoring Results: Fish and Bird Egg Tissue
Chemistry, Newport Bay Watershed. Prepared by CH2M Hill for Orange County. August 12,
2010.
Byron, E., G. Santolo, P. Sexton, K. Ashby and D. Apt. 2012. 2011 Selenium Monitoring
Results: Fish and Bird Egg Tissue Chemistry, Newport Bay Watershed. Prepared for Orange
County. January 18, 2012.
Byron, E., G. Santolo, H. Ohlendorf. 2013. Selenium and organochlorine compounds in Newport
Bay watershed fish and bird eggs, 2012. Prepared for Orange County. January 7, 2013.
Byron, E. and G. Santolo. 2014. Selenium and Organochlorine Compounds in Newport Bay
Watershed Fish and Bird Eggs, 2013. Prepared by CH2M Hill for Orange County. March 20,
2014.
D-22
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Lambing, J.H., D.A. Nimick and J.R. Knapton. 1994. Physical, chemical, and biological data for
detailed study of the Sun River irrigation project, Freezout Lake wildlife management area, and
Benton Lake national wildlife refuge, West-Central Montana, 1990-92, with selected data for
1987-89. U.S. Geological Survey. Open-File Report 94-120. Helena, Montana 1994.
Low, W.H and W.H. Mullins. 1990. Reconnaissance investigation of water quality, bottom
sediment, and biota associated with irrigation drainage in the American Falls reservoir area,
Idaho, 1988-1989. U.S. Geological Survey. Water-Resources Investigations Report 90-4120.
Boise, Idaho 1990.
Ong, K., T.F. O'Brien, and M.D. Rucker. 1991. Reconnaissance investigation of water quality,
bottom sediment, and biota associated with irrigation drainage in the middle Rio Grande Valley
and Bosque del Apache national wildlife refuge, New Mexico, 1988-89. U.S. Geological Survey.
Water-Resources Investigations Report 91-4036. Albuquerque, New Mexico 1991.
Rinella, F.A. and C.A. Schuler. 1992. Reconnaissance investigation of water quality, bottom
sediment, and biota associated with irrigation drainage in the Malheur national wildlife refuge,
Harney County, Oregon, 1988-89. U.S. Geological Survey. Water-Resources Investigations
Report 91-4085. Portland, Oregon 1992.
Rinella, F.A., W.H. Mullins, C.A. Schuler. 1994. Reconnaissance investigation of water quality,
bottom sediment, and biota associated with irrigation drainage in the Owyhee and Vale projects,
Oregon and Idaho, 1990-91. U.S. Geological Survey. Water-Resources Investigations Report 93-
4156. Portland, Oregon 1994.
U.S. EPA (U.S. Environmental Protection Agency). 2016a. Aquatic Life Ambient Water Quality
Criteria for Selenium - Freshwater 2016. EPA 822-R-16-006. Office of Water, Office of Science
and Technology, Washington, DC.
WVDEP. (West Virginia Department of Environmental Protection). 2010. Selenium induced
developmental effects among fishes in select West Virginia waters. January 2010. 55 pp.
WVDEP. (West Virginia Department of Environmental Protection). 2019. WV 2008 Birds Eggs
Summary (Draft). Excel spreadsheet obtained from WVDEP February 22, 2019.
D-23
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