United States Office of Water EPA 822-R-16-006 Environmental Protection 4304T June 2016 Agency

Aquatic Life Ambient Water Quality

Criterion for

Selenium Freshwater

2016

U.S. Environmental Protection Agency

Office of Water

Office of Science and Technology

Washington, D.C.

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TABLE OF CONTENTS Table of Contents ............................................................................................................................ ii List of Tables ...................................................................................................................................v List of Figures ................................................................................................................................ vi Notice ............................................................................................................................................ vii Foreword ...................................................................................................................................... viii Acknowledgements ........................................................................................................................ ix Acronyms ....................................................................................................................................... xi Executive Summary ...................................................................................................................... xii 1 Introduction and Background ...................................................................................................1

History of the EPA Recommended Selenium AWQC for Aquatic Life .......................... 1 1.12 Problem Formulation ................................................................................................................4

Overview of Selenium Sources and Occurrence .............................................................. 4 2.1 Environmental Fate and Transport of Selenium in the Aquatic Environment ................. 8 2.2

Selenium Species in Aquatic Systems ........................................................................ 8 2.2.1 Bioaccumulation of Selenium in Aquatic Systems ................................................... 10 2.2.2

Mode of Action and Toxicity of Selenium..................................................................... 12 2.3 Narrow Margin between Sufficiency and Toxicity of Selenium ................................... 14 2.4 Interactions with Mercury .............................................................................................. 15 2.5 Assessment Endpoints .................................................................................................... 16 2.6 Measures of Effect ......................................................................................................... 19 2.7

Fish Tissue................................................................................................................. 20 2.7.1 Water ......................................................................................................................... 23 2.7.2 Summary of Assessment Endpoints and Measures of Effect .................................... 24 2.7.3 Conceptual Model of Selenium Effects on Aquatic Life .......................................... 25 2.7.4 Analysis Plan for Derivation of the Chronic Fish Tissue-Based Criterion 2.7.5Elements .................................................................................................................... 26

Analysis Plan for Derivation of the Fish Tissue Criterion Elements Duration ......... 27 2.7.6 Analysis Plan for Derivation of the Fish Tissue Criterion Elements Return 2.7.7Frequency .................................................................................................................. 28

Analysis Plan for Derivation of Chronic Water-based Criterion Element ................ 29 2.7.8 Analysis Plan for Derivation of the Water Criterion Elements Duration ................. 31 2.7.9

Analysis Plan for Intermittent-Exposure Water-based Criterion Element 2.7.10Derivation .................................................................................................................. 32

3 Effects Analysis for Freshwater Aquatic Organisms .............................................................34 Chronic Tissue-Based Selenium Criterion Element Concentration ............................... 34 3.1

Acceptable Studies of Fish Reproductive Effects for the Four Most Sensitive 3.1.1Genera ....................................................................................................................... 35

Summary of Acceptable Studies of Fish Reproductive Effects ................................ 44 3.1.2

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Derivation of Tissue Criterion Element Concentrations ........................................... 47 3.1.3 Invertebrate Chronic Effects ..................................................................................... 54 3.1.4 Summary of Relevant Invertebrate Tests .................................................................. 57 3.1.5 Selenium Fish Tissue Toxicity Data Fulfilling Minimum Data Needs ..................... 58 3.1.6

Chronic Water Column-based Selenium Criterion Element .......................................... 60 3.2 Translation from Fish Tissue Concentration to Water Column Concentration ........ 60 3.2.1 Equation Parameters .................................................................................................. 69 3.2.2 Food-Web Models ..................................................................................................... 81 3.2.3 Classifying Categories of Aquatic Systems .............................................................. 82 3.2.4 Deriving Protective Water Column Concentrations for Lentic and Lotic System 3.2.5Categories .................................................................................................................. 87

Derivation of Averaging Period for Chronic Water Criterion Element .................... 93 3.2.6 Intermittent-Exposure Water Criterion Element: Derivation from the Chronic Water 3.3

Criterion Element ........................................................................................................... 94 4 National Criterion for Selenium in Fresh Waters ...................................................................98

Protection of Downstream Waters ............................................................................... 102 4.15 Site-specific Criteria .............................................................................................................103 6 Effects Characterization .......................................................................................................104

Fish and Amphibians .................................................................................................... 104 6.1 Principles for Using Studies for which EC10s Cannot Be Calculated ..................... 104 6.1.1 Acceptable Studies of Fish Reproductive Effects of Genera that were not among 6.1.2the Four Most Sensitive Genera .............................................................................. 105

Reproductive Effects in Catfish (Ictaluridae).......................................................... 111 6.1.3 Reproductive Effects in Amphibians (Xenopus laevis)........................................... 116 6.1.4 Reproductive Studies Not Used in the Numeric Criterion Derivation .................... 116 6.1.5 Salmo GMCV: EPA Re-analysis of a Key Study Used in Criterion Derivation..... 119 6.1.6 Impact of Number of Tested Species on Criterion Derivation................................ 120 6.1.7 Comparisons between Concentrations in Different Tissues ................................... 120 6.1.8 Studies of Non-Reproductive Effects ...................................................................... 121 6.1.9 Special conditions for consideration of primacy of water column criterion 6.1.10elements over fish tissue criterion elements ............................................................ 126

Water ............................................................................................................................ 127 6.2 Validation of Translation Equation for Developing Water Column 6.2.1Concentrations ......................................................................................................... 127

Sulfate-Selenium Interactions ................................................................................. 130 6.2.2 Uncertainty ................................................................................................................... 131 6.3

Tissue Criterion Element ......................................................................................... 131 6.3.1 Trophic Transfer Factors ......................................................................................... 136 6.3.2 Enrichment Factors ................................................................................................. 138 6.3.3 Water Values ........................................................................................................... 140 6.3.4

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Protection of Threatened or Endangered Species ........................................................ 140 6.4 Special Consideration for Pacific Salmonid Juveniles ............................................ 142 6.4.1

Aquatic-Dependent Wildlife is Beyond the Scope of this Aquatic Criteria 6.5Derivation.................................................................................................................