United States Office of Water EPA-821-R-13-003

Environmental Protection Washington, DC 20460 April 2013

Agency

Environmental Assessment 

for the Proposed Effluent 

Limitations Guidelines and 

Standards for the Steam 

Electric Power Generating 

Point Source Category
Environmental Assessment for the 

Proposed Effluent Limitations Guidelines 

and Standards for the Steam Electric Power 

Generating Point Source Category

EPA-821-R-13-003

April 2013

U.S. Environmental Protection Agency

Office of Water (4303T)

Engineering and Analysis Division

1200 Pennsylvania Avenue, NW

Washington, DC 20460
Acknowledgements and Disclaimer

This report was prepared by the Environmental Protection Agency. Neither the United 

States Government nor any of its employees, contractors, subcontractors, or their employees 

make any warrant, expressed or implied, or assume any legal liability or responsibility for any 

third party’s use of or the results of such use of any information, apparatus, product, or process 

discussed in this report, or represents that its use by such party would not infringe on privately 

owned rights.
Table of Contents

i

TABLE OF CONTENTS

Page

ACRONYMS ................................................................................................................................... vii

GLOSSARY ..................................................................................................................................... ix

SECTION 1 INTRODUCTION..........................................................................................................1-1

SECTION 2 BACKGROUND AND SCOPE........................................................................................2-1

SECTION 3 ENVIRONMENTAL AND HUMAN HEALTH CONCERNS..............................................3-1

3.1 Types of Pollutants Discharged in Steam Electric Waste Streams...........................3-3

3.1.1 Metals...........................................................................................................3-3

3.1.2 Nutrients.......................................................................................................3-9

3.1.3 TDS.............................................................................................................3-10

3.2 Loadings Associated with Combustion Wastewater ..............................................3-12

3.2.1 Annual Baseline Pollutant Loadings..........................................................3-12

3.2.2 Comparison of Steam Electric Loadings to Other Industries.....................3-14

3.2.3 Comparison of Steam Electric Loadings to Publicly Owned 

Treatment Works........................................................................................3-15

3.2.4 Pollutant Loadings to the Chesapeake Bay Watershed ..............................3-19

3.2.5 Pollutant Loadings to the Great Lakes Watershed .....................................3-22

3.3 Long Environmental Recovery Times Associated with Pollutants in Steam 

Electric Waste Streams...........................................................................................3-24

3.4 Discharge to Sensitive Environments.....................................................................3-26

3.4.1 Proximity to Impaired Waters....................................................................3-27

3.4.2 Proximity to Fish Consumption Advisory Waters .....................................3-30

3.4.3 Proximity to Threatened and Endangered Species Habitats.......................3-31

3.4.4 Proximity to Drinking Water Resources ....................................................3-32

3.5 Documented Environmental Impacts .....................................................................3-33

3.5.1 Case Studies and Damage Cases Documenting Surface Water Impacts....3-34

3.5.2 Case Studies and Damage Cases Documenting Ground Water Impacts....3-38

3.5.3 Potential for Impacts to Occur in Other Locations.....................................3-40

SECTION 4 EXPOSURE PATHWAYS..............................................................................................4-1

4.1 Combustion Wastewater Discharge and Leachate Entering Surface Waters...........4-2

4.1.1 Factors Controlling Environmental Impacts in Surface Waters...................4-3

4.1.2 Assessment of the Surface Water Exposure Pathway ..................................4-4

4.2 Leaching to Ground Water .....................................................................................4-15

4.2.1 Factors Controlling Environmental Impacts to Ground Water ..................4-15

4.2.2 Assessment of the Ground Water Exposure Pathway ................................4-20

4.3 Combustion Residuals Surface impoundments as Attractive Nuisance .................4-21

SECTION 5 CURRENT IMPACTS FROM STEAM ELECTRIC INDUSTRY.........................................5-1

5.1 Ecological Impacts....................................................................................................5-1

5.1.1 Lethal Effects of Selenium...........................................................................5-1

5.1.2 Sublethal Effects of Selenium ......................................................................5-2

5.1.3 Lethal Effects of Other Metals.....................................................................5-3
Table of Contents

TABLE OF CONTENTS (Continued)

Page

ii

5.1.4 Sublethal Effects of Other Metals ................................................................5-6

5.2 Potential for Human Health Effects..........................................................................5-6

5.3 Quantified Environmental Impacts...........................................................................5-7

5.3.1 Water Quality Impacts..................................................................................5-8

5.3.2 Wildlife Impacts...........................................................................................5-9

5.3.3 Human Health Impacts...............................................................................5-13

SECTION 6 ENVIRONMENTAL IMPROVEMENTS UNDER THE PROPOSED REGULATORY 

OPTIONS...........................................................................................................................6-1

6.1 Loading Reductions Under the Proposed Regulatory Options.................................6-6

6.2 Key Environmental Improvements.........................................................................6-13

6.2.1 Improvements in Water Quality Under the Preferred Options...................6-16

6.2.2 Reduced Threat to Wildlife Under the Preferred Option ...........................6-16

6.2.3 Reduced Human Health Cancer Risk Under the Preferred Option ............6-17

6.2.4 Reduced Threat of Non-Cancer Human Health Effects Under the 

Preferred Option .........................................................................................6-17

6.3 Pollutant-Specific Improvements ...........................................................................6-18

6.3.1 Arsenic........................................................................................................6-19

6.3.2 Mercury ......................................................................................................6-22

6.3.3 Selenium.....................................................................................................6-25

6.3.4 Cadmium ....................................................................................................6-30

6.3.5 Thallium .....................................................................................................6-33

6.4 Improvements to Sensitive Environments and Watersheds....................................6-36

6.4.1 Impaired Waters .........................................................................................6-36

6.4.2 Threatened and Endangered Species..........................................................6-39

6.4.3 Fish Advisory Waters.................................................................................6-39

6.4.4 Sensitive Watersheds: Great Lakes and Chesapeake Bay..........................6-39

6.5 Environmental and Human Health Improvements in Downstream Surface 

Water.......................................................................................................................6-45

6.6 Attractive Nuisances...............................................................................................6-48

6.7 Other Secondary Improvements.............................................................................6-48

SECTION 7 CONCLUSIONS ...........................................................................................................7-1

SECTION 8 REFERENCES .............................................................................................................8-1

APPENDIX A — LITERATURE REVIEW METHODOLOGY AND RESULTS

APPENDIX B — PROXIMITY ANALYSES SUPPORTING TABLES

APPENDIX C — WATER QUALITY MODEL METHODOLOGY

APPENDIX D — WILDLIFE MODEL METHODOLOGY

APPENDIX E — HUMAN HEALTH MODEL METHODOLOGY

APPENDIX F — ADDITIONAL MODEL RESULTS

APPENDIX G — METHODOLOGY FOR NON-MODELED OPTIONS
List of Tables

iii

List of Tables

Page

2-1 Steam Electric Waste Streams Evaluated in the EA........................................................ 2-2

2-2 Number of Plants Evaluated in the EA............................................................................ 2-4

3-1 Key Metals Found In Combustion Wastewater............................................................... 3-4

3-2 Annual Baseline Pollutant Discharges from the Steam Electric Industry ..................... 3-13

3-3 Pollutant Loadings for the Final 2010 Effluent Guidelines Planning Process: Top 

10 Point Source Categories............................................................................................ 3-14

3-4 Comparison of Average Pollutant Loadings in the Evaluated Waste Streams to an 

Average POTW.............................................................................................................. 3-18

3-5 Estimated Number of POTW Equivalents for Total Pollutant Loadings from the 

Evaluated Waste Streams............................................................................................... 3-19

3-6 Comparison of Steam Electric Pollutant Loadings to Other Point Source 

Discharges to the Chesapeake Bay Watershed .............................................................. 3-20

3-7 Estimated Number of POTW Equivalents for Pollutant Loadings to the 

Chesapeake Bay Watershed from the Evaluated Waste Streams .................................. 3-21

3-8 Steam Electric Pollutant Loadings to the Great Lakes Watershed ................................ 3-23

3-9 Estimated Number of POTW Equivalents for Pollutant Loadings to the Great 

Lakes from the Evaluated Waste Streams ..................................................................... 3-24

3-10 Number and Percentage of Immediate Receiving Waters Identified as a Sensitive 

Environment................................................................................................................... 3-27

3-11 Number and Percentage of Immediate Receiving Waters Classified as Impaired 

for a Pollutant Associated with the Evaluated Waste Streams...................................... 3-28

3-12 Number and Percentage of Immediate Receiving Waters Issued a Fish 

Consumption Advisory for a Pollutant Associated with the Evaluated Waste 

Streams........................................................................................................................... 3-30

3-13 Comparison of Number and Percentage of Steam Electric Power Plants Located 

within 5 Miles of a Drinking Water Resource ............................................................... 3-33

3-14 Summary of Select Documented Surface Water Impact Case Studies.......................... 3-35

4-1 Combustion Wastewater Environmental Pathways and Routes of Exposure 

Evaluated in the EA ......................................................................................................... 4-2

4-2 Final Outfall Receiving Water Types for Steam Electric Power Plants Within 

Scope of the Loadings Analysis....................................................................................... 4-3

4-3 Metals Considered for Analysis in the Receiving Water Model ..................................... 4-8

4-4 Metal Concentrations in Leachate Under Acidic Conditions (pH of 1.0 to 6.5) ........... 4-17

4-5 Metal Concentrations in Leachate Under Neutral Conditions (pH of 6.5 to 7.5).......... 4-17

4-6 Metal Concentrations in Leachate Under Basic Conditions (pH of 7.5 to 14).............. 4-18
List of Tables

List of Tables (Continued)

Page

iv

4-7 Range of Fly Ash and FGD Total Content and Leaching Test Results (Initial 

Screening Concentrations) for Trace Metals ................................................................. 4-20

5-1 Summary of Studies Evaluating Lethal Effects of Metals in Combustion 

Wastewater....................................................................................................................... 5-4

5-2 Median Lethal Concentrations (LC50) for Metals in Combustion Wastewater ............... 5-5

5-3 Number and Percentage of Immediate Receiving Waters with Estimated Water 

Concentrations that Exceed the Water Quality Criteria................................................... 5-9

5-4 Comparison of Modeled Selenium Concentrations in Fish Tissue to Documented 

Concentrations of Selenium in Fish Tissue Known to Cause Adverse Effects............. 5-10

5-5 Number and Percentage of Immediate Receiving Waters That Exceed Wildlife 

Fish Consumption NEHC for Mink and Eagle .............................................................. 5-12

5-6 Number and Percentage of Immediate Receiving Waters That Exceed Wildlife 

Fish Consumption Hazard Quotients for Mink and Eagle by Pollutant ........................ 5-13

5-7 Number and Percentage of Immediate Receiving Waters That Exceed Human 

Health Evaluation Criteria (Lifetime Excess Cancer Risk) for Inorganic Arsenic........ 5-14

5-8 Number and Percentage of Immediate Receiving Waters That Exceed NonCancer Oral Reference Dose Values.............................................................................. 5-15

5-9 Number and Percentage of Immediate Receiving Waters That Exceed NonCancer Oral Reference Dose Values by Pollutant ......................................................... 5-16

5-10 Comparison of T4 Fish Tissue Concentrations to Fish Advisory Screening Values.... 5-17

6-1 Regulatory Options Evaluated in the EA......................................................................... 6-3

6-2 Description of Environmental Improvements from Preferred Regulatory Options........ 6-4

6-3 Steam Electric Industry Pollutant Reductions for Metals, Nutrients, Chlorides, and 

TDS Under Regulatory Options....................................................................................... 6-9

6-4 Steam Electric Industry Toxic Weighted Equivalent Pollutant Reductions for 

Metals, Nutrients, Chlorides, and TDS Under Regulatory Options .............................. 6-11

6-5 Key Environmental Improvements Under the Regulatory Options............................... 6-14

6-6 Key Environmental Improvements for Arsenic Under the Regulatory Options............ 6-20

6-7 Key Environmental Improvements for Mercury Under the Regulatory Options.......... 6-23

6-8 Comparison of Estimated Selenium Concentrations in Fish to Documented 

Literature Fish Impacts.................................................................................................. 6-27

6-9 Key Environmental Improvements for Selenium Under the Regulatory Options......... 6-28

6-10 Key Environmental Improvements for Cadmium Under the Regulatory Options........ 6-31

6-11 Key Environmental Improvements for Thallium Under the Regulatory Options ......... 6-34

6-12 Loading Reductions to Impaired Waters by Impairment Type ..................................... 6-37
List of Tables

List of Tables (Continued)

Page

v

6-13 Total Loadings Removed to the Great Lakes Watershed Under the Regulatory 

Options........................................................................................................................... 6-41

6-14 Total Loading Reductions to the Chesapeake Bay Watershed Under the 

Regulatory Options........................................................................................................ 6-43

6-15 Key Environmental Improvements for Downstream Waters Under the Regulatory 

Options........................................................................................................................... 6-46
List of Figures

vi

List of Figures

Page

3-1 Location of Plants that Directly Discharge Combustion Wastewater to a Surface 

Water Impaired due to Arsenic, Mercury, and Selenium .............................................. 3-28

3-2 Location of Plants that Directly Discharge Combustion Wastewater to a Surface 

Water Impaired due to Metals Other than Mercury....................................................... 3-29

3-3 Location of Plants that Directly Discharge Combustion Wastewater to a Surface 

Water Impaired due to Nutrients.................................................................................... 3-29

3-4 Location of Plants that Directly Discharge to a Surface Water with a Fish 

Consumption Advisory for Cadmium, Lead, and Mercury ........................................... 3-31

4-1 Overview of Receiving Water Model.............................................................................. 4-6

4-2 Water Quality Model: Pollutant Fate in the Water Body .............................................. 4-10
Acronyms

vii 

ACRONYMS

ARCS Assessment and Remediation of Contaminated Sediments 

ASTM American Society for Testing and Materials

ATSDR Agency for Toxic Substances and Disease Registry

BAT Best Available Technology Economically Achievable

BCF Bioconcentration factor 

BPT Best Practicable Control Technology Currently Available 

CCR Coal combustion residuals 

CFR Code of Federal Regulations

CSCL Chemical stressor concentration limit

CSF Cancer slope factor

CWA Clean Water Act

DCN Document control number 

DMR Discharge monitoring report 

DOE Department of Energy

EA Environmental assessment 

ELGs Effluent Limitations Guidelines and Standards 

EP Extraction procedure 

EPA U.S. Environmental Protection Agency 

FGD Flue gas desulfurization

HQ Hazard quotient 

IRIS Integrated Risk Information System 

LADD Lifetime average daily dose 

lb/yr Pounds per year 

LC50 Median lethal concentration 

LECR Lifetime excess cancer risk

MCL Maximum contaminant level

MRL Minimal risk level 

MGD Million gallons per day 

mg/day Milligrams per day 

mg/kg Milligrams per kilogram 

mg/L Milligrams per liter

NEHC No effect hazard concentration

NOAEL No-observed-adverse-effect level

NPDES National Pollutant Discharge Elimination System 

NRWQC National Recommended Water Quality Criteria

NSPS New Source Performance Standards
Acronyms

viii

OSWER Office of Solid Waste and Emergency Response

POTW Publicly owned treatment works 

ppm Parts per million

PSES Pretreatment Standards for Existing Sources

PSNS Pretreatment Standards for New Sources

RCRA Resource Conservation and Recovery Act 

RfD Reference dose

SDWA Safe Drinking Water Act

SQuiRT Screening Quick Reference Table

TC Toxicity characteristic

TCLP Toxicity characteristic leaching procedure 

TDD Technical Development Document

TDS Total dissolved solids 

TMDL Total maximum daily load

TRI Toxics Release Inventory

TSS Total suspended solids 

TTHM Total trihalomethanes

TWF Toxic weighting factor

TWPE Toxic weighted pound equivalent 

μg/g Micrograms per gram

μg/L Micrograms per liter

USGS United States Geological Survey

WHO World Health Organization

WMA Wildlife Management Area

WQC Water quality criteria

WQI Water quality index
Glossary

ix

GLOSSARY

Acute – having a sudden onset or lasting a short time. An acute stimulus is severe enough to 

induce a response rapidly. The word acute can be used to define either the exposure or the 

response to an exposure (effect). The duration of an acute aquatic toxicity test is generally four

days or less and mortality is the response usually measured.

Aquifer – an underground formation or group of formations in rocks and soils containing enough 

ground water to supply wells and springs.

Benthic community – the community of organisms dwelling at the bottom of a pond, river, lake,

or ocean. 

Bioaccumulation – general term describing a process by which chemicals are taken up by an 

organism either directly from exposure to a contaminated medium or by consumption of food 

containing the chemical.

Biomagnification – result of the process of bioaccumulation and biotransfer by which tissue 

concentrations of chemicals in organisms at one trophic level exceed tissue concentrations in 

organisms at the next lower trophic level in a food chain.

Chronic – involving a stimulus that is lingering or continues for a long time; often signifies 

periods from several weeks to years, depending on the reproductive life cycle of the species. This 

term can be used to define either the exposure or the response to an exposure (effect). Chronic 

exposures typically induce a biological response of relatively slow progress and long duration.

Coal combustion residuals (CCR) – means fly ash, bottom ash, boiler slag, and flue gas 

desulfurization (FGD) materials destined for disposal. CCRs are also known as coal combustion 

wastes (CCWs) and fossil fuel combustion (FFC) wastes, when destined for disposal. 

Combustion residuals – solid wastes associated with combustion-related power plant processes, 

including fly and bottom ash from coal-, petroleum coke-, or oil-fired units; FGD solids; flue gas 

mercury control wastes; and other wastewater treatment solids associated with combustion 

wastewater.

Combustion wastewater – all combustion-related wastewaters evaluated as part of the steam 

electric proposed effluent limitations guidelines and standards (ELGs), including ash transport 

water from coal-, petroleum coke-, or oil-fired units; air pollution control wastewater (e.g., FGD 

wastewater, flue gas mercury control wastewater, carbon capture wastewater); and leachate from 

landfills or surface impoundments containing combustion residuals.

Criterion maximum concentration – is an estimate of the highest concentration of a material in 

surface water to which an aquatic community can be exposed briefly without resulting in an 

unacceptable effect.
Glossary

x

Direct discharge – wastewater discharged directly into a waterway under a National Pollutant 

Discharge Elimination System (NPDES) permit through a defined conveyance or system such as 

outlet pipes; a point source.

Edema – swelling caused by fluid in body tissues.

Effluent limitation – under Clean Water Act (CWA) section 502(11), any restriction, including 

schedules of compliance, established by a state or the Administrator on quantities, rates, and 

concentrations of chemical, physical, biological, and other constituents which are discharged 

from point sources into navigable waters, the waters of the contiguous zone, or the ocean.

Evaluated waste streams – subset of combustion wastewaters evaluated in the environmental 

assessment (EA) and Benefits and Cost Analysis that includes FGD wastewater, fly ash transport 

water, bottom ash transport water, and leachate from landfills or surface impoundments 

containing combustion residuals. 

Exposure – the contact or co-occurrence of a stressor with a receptor.

Gasification wastewater – taken collectively as if from one source, wastewater from all sources 

associated with the gasification process or related chemical recovery processes at an integrated 

gasification combined cycle operation. Gasification wastewater includes, but is not limited to, 

slag handling wastewater, fly ash stream, sour/grey water (which consists of condensate from gas 

cooling, as well as other waste streams), carbon dioxide (CO2)/steam stripper wastewater, air 

separation unit blowdown, and sulfur recovery unit blowdown.

Ground water – water in a saturated zone or stratum beneath the surface of land.

Hematological – pertaining to or emanating from blood cells.

Histopathological – pertaining to tissue changes.

Impaired waters – a surface water is classified as a 303(d) impaired water when pollutant 

concentrations exceed water quality standards and the surface water can no longer meet its 

designated uses (e.g., drinking, recreation, and aquatic habitat).

Indirect discharge – wastewater discharged directly to a publicly owned sewage treatment works 

(POTW).

Invertebrates – animals without a backbone or spinal column; macroinvertebrates are 

invertebrates that can be seen without a microscope (macro), such as aquatic insects, worms, 

clams, snails, and crustaceans.

Landfill – a disposal facility or part of a facility where solid waste, sludges, or other process 

residuals are placed in or on any natural or manmade formation in the earth for disposal and 

which is not a storage pile, a land treatment facility, a surface impoundment, an underground 

injection well, a salt dome or salt bed formation, an underground mine, a cave, or a corrective 

action management unit.
Glossary

xi

Leachate – liquid, including any suspended or dissolved constituent in the liquid that has 

percolated through or drained from waste or other materials emplaced in a landfill, or that pass 

through the containment structure (e.g. bottom, dikes, berms) of a surface impoundment. 

Leachate also includes the terms seepage, leak, and leakage, which are generally used in 

reference to leachate from an impoundment.

Lentic water body – still or slow-moving water, such as lakes or ponds.

Lethal – causing death by direct action.

Lotic water body – flowing water, such as streams and rivers.

Median lethal concentration (LC50) – a statistically or graphically estimated concentration that is 

expected to be lethal to 50 percent of a group of organisms under specified conditions.

Mortality – death rate or proportion of deaths in a population.

Partition coefficient – the ratio of a pollutant concentration in one medium compared to another 

(e.g., dissolved in the water column, sorbed to suspended sediment, and sorbed to benthic 

sediment in a receiving water). 

Piscivorous – habitually feeds on fish.

Point source – any discernable, confined, and discrete conveyance from which pollutants are or 

may be discharged. See CWA section 502(14).

Population – an aggregate of individuals of a species within a specified location in space and 

time.

Receptor – the ecological or human entity exposed to a stressor.

Sediment – particulate material lying below water.

Sensitivity – in relation to toxic substances, organisms that are more sensitive exhibit adverse 

(toxic) effects at lower exposure levels than organisms that are less sensitive.

Stressor – any physical, chemical, or biological entity that can induce an adverse response.

Sublethal – below the concentration that directly causes death. Exposure to sublethal 

concentrations of a substance can produce effects on behavior, biochemical and/or physiological 

functions, and the structure of cells and tissues in organisms.

Surface impoundments – a facility or part of a facility which is a natural topographic depression, 

man-made excavation, or diked area formed primarily of earthen materials (although it may be 

lined with man-made materials), which is designed to hold an accumulation of liquid process 

wastes or process wastes containing free liquids, and which is not an injection well. Examples of 

surface impoundments are holding, storage, settling, and aeration pits, ponds, and lagoons. 

Surface impoundments are used to receive combustion residuals that have been sluiced (flushed 
Glossary

xii

or mixed with water to facilitate movement), or wastes from wet air pollution control devices, 

often in addition to other solid wastes.

Surface water – all water naturally open to the atmosphere, such as rivers, lakes, reservoirs, 

streams, and seas.

Teratogenic – able to disturb the growth and development of an embryo or fetus. 

Trophic level – position of an organism in the food chain.

Toxic pollutants – as identified under the CWA, 65 pollutants and classes of pollutants, of which 

126 specific substances have been designated priority toxic pollutants. See Appendix A to 40 

CFR 423.
Section 1—Introduction

1-1 

SECTION 1

INTRODUCTION 

The U.S. Environmental Protection Agency (EPA) is proposing revised effluent 

limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Point 

Source Category (40 CFR 423). In support of the development of the revised ELGs, EPA 

conducted an environmental assessment (EA) to evaluate the environmental impact of pollutant 

loadings released under current (i.e., baseline) discharge practices and assess the potential 

environmental improvement from pollutant loading reductions under varying regulatory options. 

Based on evidence in the literature, documented cases studies, and modeled receiving 

water pollutant concentrations, it is clear that current combustion wastewater discharge practices 

at steam electric power plants impact the water quality in receiving waters, impact the wildlife in 

the surrounding environments, and pose a potential human health threat to nearby communities. 

Substantial evidence exists that metals (e.g., arsenic, cadmium, mercury, selenium) from 

combustion wastewater discharges transfer from the aquatic environment to terrestrial food 

webs, indicating a potential for broader impacts to ecological systems by altering population 

diversity and community dynamics in the areas surrounding steam electric power plants. 

Ecosystem recovery from exposure to combustion wastewater discharges can be extremely slow 

and even short periods of exposure (e.g., less than a year) can cause observable ecological 

impacts that last for years. 

Steam electric power plants discharge combustion wastewater into water bodies used for 

recreation and can present a potential threat to human health. Documented fish kills in waters 

that receive combustion wastewater discharges have resulted in states issuing fish advisories to 

protect the public from exposure to fish with elevated pollutant concentrations. Leachate from 

surface impoundments and landfills containing combustion residuals are known to impact 

off-site ground water and drinking water wells at concentrations above maximum contaminant 

level (MCL) drinking water standards, posing a potential threat to human health. 

The goal of the EA was to answer the following five questions regarding the evaluated 

waste streams included in the analysis:

• What are the environmental concerns under current (i.e., baseline) discharge 

practices?

• What are the environmental and exposure pathways for steam electric industry 

discharges to impact water quality, wildlife, and human health? 

• What are the baseline environmental impacts to water quality and wildlife? 

• What are the potential impacts to human health from baseline discharges?

• What are the improvements to water quality, wildlife, and human health under the 

regulatory options?

The EA evaluated environmental concerns and potential exposures (wildlife and humans) 

to pollutants commonly found in combustion wastewater discharges from steam electric power 

plants. EPA completed both qualitative and quantitative analyses. Qualitative analyses include 
 

 

 

 

 

 

 

 

 

 

 

 

 

Section 1—Introduction 

reviewing documented site impacts in literature, case studies, and damage cases; pollutant 

loadings to receiving waters; discharges to sensitive environments; and the effect of pollutant 

exposure on ecological and human receptors. To quantify baseline impacts and improvements 

under the proposed Steam Electric ELGs, EPA developed models to determine pollutant 

concentrations in the immediate and downstream receiving waters, pollutant concentrations in 

fish tissue, and exposure doses to ecological and human receptors from fish consumption. EPA 

compared the values calculated by the models to benchmarks to determine the extent of the 

environmental impacts nationwide. 

This report presents the methodology and results of the qualitative and quantitative 

analyses performed to evaluate baseline discharges from steam electric power plants and 

improvements under the regulatory options. The analyses presented in this report reflect the 

current conditions in the industry. The results do not reflect changes in the industry that may 

occur as a result of future EPA rulemakings such as EPA’s Office of Solid Waste and 

Emergency Response (OSWER)’s Coal Combustion Residual (CCR) rule and Office of Air’s 

National Emission Standards for Hazardous Air Pollutants (NESHAP). 

In addition to the EA, the proposed Steam Electric ELGs are supported by a number of 

reports including: 

•	 Technical Development Document for Proposed Effluent Limitations Guidelines and 

Standards for the Steam Electric Power Generating Point Source Category (TDD), 

Document No. EPA 821-R-13-002. This report includes background on the proposed 

ELGs; applicability and summary of the proposed ELGs; industry description; 

wastewater characterization and identifying pollutants of concern; treatment 

technologies and pollution prevention techniques; and documentation of EPA’s 

engineering analyses to support the proposed ELGs including cost estimates, 

pollutant loadings, and non-water quality impact assessment (DCN SE01964). 

•	 Benefits and Cost Analysis for the Proposed Effluent Limitations Guidelines and 

Standards for the Steam Electric Power Generation Point Source Category (Benefits 

and Cost Analysis), Document No. EPA 821-R-13-004. This report summarizes the 

monetary benefits and societal costs that result from implementation of the proposed 

ELGs (DCN SE03172). 

•	 Regulatory Impact Analysis for Proposed Effluent Limitations Guidelines and 

Standards for the Steam Electric Power Generation Point Source Category, 

Document No. EPA 821-R-13-005. This report presents a profile of the steam electric 

industry, a summary of the costs and impacts associated with the regulatory options, 

and an assessment of the proposed ELGs’ impact on employment and small 

businesses (DCN SE03170). 

These reports are available in the public record for this rule and on EPA’s web site at 

http://water.epa.gov/scitech/wastetech/guide/steam_index.cfm. 

The proposed ELGs for the Steam Electric Power Generating Point Source Category are 

based on data generated or obtained in accordance with EPA’s Quality Policy and Information 

Quality Guidelines. EPA’s quality assurance (QA) and quality control (QC) activities for this 

1-2
 
Section 1—Introduction

1-3 

rulemaking include the development, approval and implementation of Quality Assurance Project 

Plans for the use of environmental data generated or collected from all sampling and analyses, 

existing databases and literature searches, and for the development of any models which used 

environmental data. Unless otherwise stated within this document, the data used and associated 

data analyses were evaluated as described in these quality assurance documents to ensure they 

are of known and documented quality, meet EPA's requirements for objectivity, integrity and 

utility, and are appropriate for the intended use. 
Section 2—Background and Scope

2-1 

SECTION 2

BACKGROUND AND SCOPE 

The proposed Steam Electric effluent limitations guidelines and standards (ELGs) apply 

to establishments primarily engaged in generating electricity for distribution and/or sale, which 

results primarily from a process utilizing fossil-type fuels (coal, petroleum coke, oil, gas) or 

nuclear fuel in conjunction with a thermal cycle using the steam water system as the 

thermodynamic medium (40 CFR 423.10). The U.S. Environmental Protection Agency (EPA) is 

proposing to revise or establish Best Available Technology Economically Achievable (BAT) 

limitations, New Source Performance Standards (NSPS), Pretreatment Standards for Existing 

Sources (PSES), and Pretreatment Standards for New Sources (PSNS) that may apply to 

discharges of seven wastewater streams: flue gas desulfurization (FGD) wastewater, fly ash 

transport water, bottom ash transport water, leachate from landfills and surface impoundments 

containing coal combustion residuals (CCR), wastewater from flue gas mercury control (FGMC) 

systems, wastewater from gasification systems, and nonchemical metal cleaning wastes. See the 

Technical Development Document for the Proposed Effluent Limitations Guidelines and 

Standards for the Steam Electric Power Generating Point Source Category (TDD) (DCN

SE01964) for more information on the rule applicability and definitions, waste streams and 

pollutants of concern, treatment technologies, baseline and option pollutant loadings, costs of 

implementing treatment technologies, and option selection.

In this report, EPA uses the term 

“combustion wastewater” as all combustionrelated wastewaters evaluated as part of the 

proposed Steam Electric ELGs. For the the 

environmental assessment (EA), EPA 

evaluated only a subset of the waste streams 

(see Table 2-1 below).1 “Combustion 

residuals” are the solid wastes associated with 

combustion-related power plant processes, 

including fly and bottom ash; FGD solids; flue 

gas mercury control wastes; and other 

wastewater treatment solids associated with 

combustion wastewater. The term “coal 

combustion residuals (CCR)” means solid 

wastes associated with the CCR rule that 

includes fly ash, bottom ash, boiler slag, and 

FGD materials destined for solid waste 

disposal. 

 

1 EPA evaluated technology options associated with FGMC wastewater, gasification wastewater, and nonchemical 

metal cleaning wastes as part of the regulatory options. However, no plants currently discharge FGMC wastewater; 

all existing gasification plants are operating the technology used as the basis for the regulatory option; and the 

proposed limitations and standards for nonchemical metal cleaning wastes are equal to current Best Practicable 

Control Technology Currently Available (BPT) limitations for existing direct dischargers. Therefore, EPA estimated 

zero compliance costs and zero pollutant reductions associated with these waste streams and did not include these 

three waste streams in the EA.

Many steam electric power plants use large surface 

impoundments to store and treat wastewaters. These 

impoundments are hydrologically connected to surface 

and ground water.
Section 2—Background and Scope

2-2 

Steam electric power plants generate solid residuals from fuel combustion and from 

emission control technologies. These solid residuals include fly ash, bottom ash, and FGD solids. 

Plants remove these solid materials through both wet and dry handling methods. Dry handling 

typically involves transferring the solids to a storage silo or outdoor storage pile, either to be 

disposed of in a landfill or, depending on the particular residual, used to create beneficial byproducts such as wallboard or cement. However, many plants use wet handling systems, which 

typically transfer the wastes to a surface impoundment (e.g., ash pond) using large quantities of 

water. For example, in wet systems, bottom ash collects at the bottom of the boiler in a water 

bath, and the water containing the bottom ash is then typically transported to a surface 

impoundment for storage and/or disposal. Fly ash may be handled similarly after it is collected 

from the particulate collection system. The slurry stream exiting wet FGD systems, which 

contains 10 to 20 percent FGD solids, is typically either discharged to a surface impoundment or 

sent to an advanced wastewater treatment system prior to discharge to a receiving stream or 

reused in other plant processes. Section 4 of the TDD describes the industry waste streams in 

detail. Table 2-1 lists the specific waste streams evaluated in the EA.

Table 2-1. Steam Electric Waste Streams Evaluated in the EA 

Evaluated Waste Stream Description

Fly ash transport water Water used to convey the fly ash particles removed from the flue gas via a collection 

system. 

Untreated ash transport waters contain significant concentrations of total suspended 

solids (TSS) and metals. The effluent from ash ponds generally contains low 

concentrations of TSS; however, metals are still present in the wastewater, 

predominantly in dissolved form. Fly ash transport water contains significant 

concentration of metals, including arsenic, calcium, and titanium (see Section 6 of 

the TDD for further details).

Bottom ash transport water Water used to convey the bottom ash particles collected at the bottom of the boiler.

As noted above, untreated ash transport waters contain significant concentrations of 

TSS and metals. 

FGD wastewater Wastewater generated from a wet FGD scrubber system. Wet FGD systems are used 

to control sulfur dioxide (SO2) emissions from the flue gas generated in the plant’s 

boiler.

The pollutant concentrations in FGD wastewater vary from plant to plant depending 

on the coal type, the sorbent used, the materials of construction in the FGD system, 

the FGD system operation, the level of recycle within the absorber, and the air 

pollution control systems operated upstream of the FGD system. FGD wastewater 

contains significant concentrations of chlorides, total dissolved solids (TDS), 

nutrients, and metals, including bioaccumulative pollutants such as arsenic, mercury, 

and selenium (see Section 6 of the TDD for further details). 

Landfill and surface 

impoundment leachate

Liquid that has percolated through or drains from a landfill or a pond, where the 

steam electric power plant disposes of or stores a variety of wastes from the 

combustion process. 

Leachate contains high concentration of metals, such as boron, calcium, chloride, 

and sodium, similar to FGD and ash wastewaters. The metals present in the leachate 

are generally at lower concentrations than those seen in FGD wastewater and ash 

transport water (see Section 6 of the TDD for further details).
Section 2—Background and Scope

2-3 

Surface impoundments act as a physical 

treatment process to remove particulate 

material from wastewater through gravitational 

settling. The wastewater in surface 

impoundments can include one specific type of 

wastewater (e.g., fly ash transport water) or a 

combination of wastewaters (e.g., fly ash 

transport water and FGD wastewater). 

Additionally, plants may transfer wastewater 

streams from other operations into their on-site 

impoundments (e.g., cooling tower blowdown 

or metals cleaning wastes). The waste streams

sent to surface impoundments can also include 

coal pile runoff. Although coal pile runoff is 

not the result of a combustion process, it can 

contain many of the pollutants present in coalfired power plant combustion wastewater. Leachate or seepage may occur from surface 

impoundments or landfills containing combustion residuals. Regardless of whether they use 

surface impoundments or an advanced treatment system, plants typically discharge combustion

wastewater into the natural environment where numerous studies have raised concern regarding 

the toxicity of these waste streams [ERG, 2013f; NRC, 2006; Rowe et al., 2002; U.S. EPA, 

2007b]. Previous regulations at 40 CFR 423 control pH and polychlorinated biphenyls (PCBs) 

discharge from all waste streams and TSS and oil and grease from ash transport waters and other 

“low-volume wastes” that include air pollution control wastewater (see Section 1 of the TDD). 

Section 6 of the TDD discusses wastewater characterization and selection of pollutants of 

concern.

Based on 2009 data from the Department of Energy and additional data EPA obtained 

from the 2010 Questionnaire for the Steam Electric Power Generating Effluent Guidelines (the 

Steam Electric Survey), EPA estimates that 1,079 steam electric power plants are subject to the 

proposed regulation. However, EPA estimates that only 386 plants generate one or more of the 

waste streams that are included in the proposed revisions to the ELGs. Additionally, because 

some of these plants do not discharge any of the waste streams, already comply with the 

proposed revisions, or have plans to comply with the proposed revisions prior to January 1, 2014, 

EPA determined that only a subset (290 plants) are likely to achieve pollutant reductions as a 

result of the proposed ELGs, depending on their operations. In the EA, EPA evaluated the 

current impact and potential improvement to the environment and human health from a further 

subset of 281 plants that discharge directly to surface waters and that EPA projects will achieve 

reduced loadings as a result of the regulatory options evaluated. Table 2-2 presents the number of 

plants by discharge type (direct or indirect) included in the cost and loadings analysis presented 

in Section 10 of the TDD. 

Surface impoundments accumulate high concentrations 

of toxic pollutants from fly ash transport waters, bottom 

ash transport waters and FGD wastewater.
Section 2—Background and Scope

2-4 

Table 2-2. Number of Plants Evaluated in the EA

Plant Description

Number of 

Plants

Number of Plants in Scope of Proposed ELGs

Plants that fall under the applicability of the proposed ELGs (40 CFR 423) 1,079

Cost and Loadings Analysis

Plants for which EPA calculated loadings in the cost and loadings analyses 

(see Section 10 of the TDD)

290

Plants that discharge only to surface waters (direct discharger) 277

Plants that discharge only to Publicly Owned Treatment Works (POTWs) (indirect discharger) 9

Plants that discharge to surface waters and to a POTW (direct and indirect discharger) 4

Environmental Assessment

Plants evaluated in Steam Electric ELGs EA (includes all direct dischargers) 281

EPA conducted an extensive literature search to collect documented cases of 

environmental impacts that are relevant to steam electric power plant discharges.2 Based on 

environmental impacts identified during the literature search, EPA identified several 

environmental concerns and routes of exposure to address in the EA. The EA comprised both 

qualitative and quantitative assessments of the current impact that steam electric power plants are

having on the environment and the potential to impact human health. The EA also provided an 

assessment of the potential improvements projected to occur following implementation of the 

regulatory options considered by EPA. Qualitative analyses included reviewing documented site 

impacts in literature, case studies, and damage cases; pollutant loadings to receiving waters; 

discharges to sensitive environments; and the effect of pollutant exposure on ecological and 

human receptors. To quantify baseline impacts and improvements under the proposed Steam 

Electric ELGs, EPA developed computer models to determine pollutant concentrations in the 

immediate and downstream receiving waters, pollutant concentrations in fish tissue, and 

exposure doses to ecological and human receptors from fish consumption. EPA compared the 

values calculated by the models to benchmarks to determine the extent of the environmental 

impacts nationwide.

EPA used the results from quantitative and qualitative assessments combined with the 

literature review to evaluate and describe the environmental impacts caused by the discharge of 

the evaluated waste streams. EPA organized the remainder of this report into the following five 

sections: 

• Section 3 describes the environmental concerns associated with the evaluated waste 

streams, including a discussion of the pollutants of concern and documented case 

studies and damage cases showing negative impacts to surface water and ground 

water;

• Section 4 outlines how ecological and human receptors may be exposed to pollutants 

(i.e., environmental pathways), provides a qualitative description of factors that 

control environmental impacts for each pathway, and gives an overview of the 

 

2 EPA discusses the results of the literature review throughout this report. Appendix A provides details on the 

literature search methodology and summary of results. 
Section 2—Background and Scope

2-5 

methodology used to quantitatively evaluate the environmental and human health 

impacts;

• Section 5 presents the environmental and human health impacts based on qualitative 

review and quantitative assessments (modeling of plant-specific discharges) of 

current (baseline) discharges; 

• Section 6 presents the improvements to the environment and human health estimated 

from the implementation of the regulatory options; and

• Section 7 presents EPA’s conclusions on the environmental and human health 

improvements estimated under the proposed ELGs. 
Section 3—Environmental And Human Health Concerns

3-1 

SECTION 3

ENVIRONMENTAL AND HUMAN HEALTH CONCERNS 

Current scientific literature indicates that combustion wastewater is not a benign waste 

[NRC, 2006; Rowe et al., 2002]. Many of the common pollutants (e.g., selenium, mercury, and 

arsenic) found in the waste streams evaluated as part of the environmental assessment (i.e., fly 

ash and bottom ash transport water, flue gas desulfurization (FGD) wastewater, and leachate) 

present an increased ecological threat due to their tendency to persist in the environment and 

bioaccumulate in organisms. This often results in slow ecological recovery times following 

exposure. The toxic impacts of combustion wastewater contamination to surface waters have 

been well documented in studies of over 30 aquatic ecosystems receiving discharges from steam 

electric power plants.3

 

The U.S. Environmental Protection Agency (EPA) did not find documented cases of 

human health impacts from coal combustion wastewaters. However, documented exceedances of 

drinking water maximum contaminant levels (MCLs) downstream of steam electric power plants 

and the issuance of fish advisories in receiving waters, indicate an ongoing human health 

concern. In a number of damage cases, EPA found that ground water contamination from 

combustion wastewater resulted in pollutant concentrations exceeding MCLs, indicating a 

potential human health impact [NRC, 2006; U.S. EPA, 2007b]. There were three damage cases 

that documented instances where leachate contamination impacted private drinking water wells. 

In other damage cases, EPA documented locations where selenium in combustion wastewater

discharges resulted in fish consumption advisories being issued for surface waters (for selenium). 

For example, a series of major fish kills occurred in 1978 and 1979 at Martin Lake (Texas) due 

to the elevated concentrations of selenium in the water and fish tissue. Studies conducted 

throughout the 1980s documented histopathological and reproductive damage in the fish 

populations inhabiting the lake. In addition, the studies determined that the overall health of the 

aquatic populations near the discharge site remained adversely affected by the selenium 

pollution, despite the reduction in the annual discharge of selenium. In 1992, a fish consumption 

advisory was issued for the lake [ATSDR, 1998c]. 

Documented ecological impacts include acute effects (e.g., fish kills) and chronic effects 

(e.g., malformations, and metabolic, hormonal, and behavioral disorders) upon biota within the 

receiving water and surrounding environment. Numerous case studies and damage cases 

document the toxic impacts of combustion wastewater contamination to ground water and 

potential to impact off-site sources as a result of leaching from landfills and surface 

impoundments (often unlined) [AECOM, 2009; ASU, 2009; DRBC, 2006; EIP, 2010a and 

2010b; ERG, 2012b; Gazette, 2011; MACo, 2007; MDNRE, 2010; U.S. EPA, 2007b and 2010e]. 

A number of studies performed in the 1970s and 1980s outlined toxic impacts on ground water

from fly ash, bottom ash, and other combustion wastewater; toxic impacts include deleterious 

increases in conductivity, total suspended solids (TSS), total dissolved solids (TDS), pH, sodium, 

and metals – aluminum, arsenic, cadmium, iron, mercury, selenium, and zinc [Cherry, 2000]. 

 

3 Sources include ATSDR, 1998a, 1998b and 1998c; Charlotte Observer, 2010; DOE, 1992; EIP, 2010a and 2010b; 

Roe et al., 2005; Sorensen et al., 1983; Sorensen, 1988; Specht et al., 1984; U.S. EPA, 2007b; and Vengosh et al., 

2009.
Section 3—Environmental And Human Health Concerns

3-2 

While these sites are often assumed to be anomalies, an increasing amount of evidence indicates 

that the characteristics contributing to the documented impact (e.g., magnitude of the pollutant 

loadings, type of pollutant present in the waste, plant operations, and wastewater handling 

techniques) are common among steam electric power plant discharge locations [Cherry, 2000; 

NRC, 2006; Rowe et al., 2002]. 

EPA identified a recent study that evaluated the environmental and ecological impacts 

that steam electric industry discharges have on receiving waters in North Carolina [Ruhl, 2012]. 

The study evaluated ten surface water sites that receive combustion wastewater discharges and

determined that these sites contain high levels of contaminants as a result of these discharges. 

From the data collected between 2010 and 2012, contaminant levels at multiple sites exceeded 

drinking water standards and/or National Recommended Water Quality Criteria (NRWQC). For 

example, arsenic concentrations at two outfalls were as high as 45 micrograms per liter (μg/L) 

and 92 μg/L, respectively. The drinking water MCL for arsenic is 10 μg/L. When compared to 

the upstream pollutant concentrations at the ten North Carolina sites, data showed elevated levels 

of contaminants such as boron, chromium, selenium, bromine, arsenic, and thallium. Elevated 

pollutant concentrations were also found in lake sediments (arsenic and selenium) and pore water 

near lake bottoms (including manganese, arsenic, nickel, and bromine). Even at low 

concentrations, pollutants can cause negative impacts in the receiving water. Negative impacts to 

fish included deformities at one lake due to elevated selenium concentrations. 

This section details the following environmental concerns associated with combustion 

wastewater discharges from steam electric power plants: 

• Changes in surface water quality and sediment contamination levels;

• Changes in ground water quality and potential contamination of private drinking 

water wells; 

• Bioaccumulation of contaminants in fish and aquatic life, fish eaten by piscivorous 

wildlife (i.e., fish-eating wildlife), and fish eaten by humans; and

• Toxic effects on fish and aquatic life. 

The pollutants commonly discharged in the evaluated waste streams cause environmental 

harm by contaminating surface water and ground water (e.g., selenium concentrations from 

steam electric power plants have resulted in fish kills). Long residence times for pollutants 

following release into the environment result in pollutant bioaccumulation and binding with the 

sediment. There is documented evidence of slow ecological recovery as a result of these 

pollutant discharges. Steam electric power plants also discharge to sensitive environments (e.g., 

impaired waters, waters under a fish consumption advisory, Great Lakes, valuable estuaries, and 

drinking water sources). Some impacts might not be realized for years due to the persistent and 

bioaccumulative nature of the pollutants released. Based on the pollutant loadings calculated for 

the proposed Steam Electric ELGs, the total amount of toxic pollutants currently being released 

in wastewater discharges from steam electric power plants is significant and raises concerns 

regarding the long-term impacts to aquatic organisms, wildlife, and humans that are exposed to 

these pollutants. For details on the pollutant loadings analysis, see Section 10 of the Technical 

Development Document for the Proposed Effluent Limitations Guidelines and Standards for the 

Steam Electric Power Generating Point Source Category (TDD) (DCN SE01964).
Section 3—Environmental And Human Health Concerns

3-3 

3.1 TYPES OF POLLUTANTS DISCHARGED IN STEAM ELECTRIC WASTE STREAMS 

This section provides an overview of the pollutants in combustion wastewater discharges 

that are frequently cited as affecting local wildlife or have the potential to pose a threat to human 

health. A number of variables can affect the composition of combustion wastewater, including 

fuel composition, type of combustion process, air pollution control technologies implemented, 

and management techniques used to dispose of combustion wastewater [Carlson and Adriano, 

1993]. In addition, commingling combustion wastewater with other waste streams from the plant 

in surface impoundments can result in a chemically complex effluent that is released to the 

environment [Rowe et al., 2002]. To identify pollutants of concern for the proposed ELGs, EPA 

used the following sources of wastewater characterization data in hierarchic order: EPA’s field 

sampling program; industry-supplied data including data provided in questionnaire responses;

and various literature sources (see Section 6 of the TDD and the preamble to the proposed 

ELGs). Pollutants such as metals, nutrients, and TDS (including chloride and bromides) are the 

common pollutants found in combustion wastewater that have been associated with documented 

environmental impacts or could have the potential to cause environmental impacts based on the 

loadings and concentrations present in the evaluated waste streams. 

3.1.1 Metals

Studies commonly cite metals as the primary cause of ecological damage following 

exposure to combustion wastewater [Rowe et al., 1996; Lemly, 1997; Hopkins et al., 2000; 

Rowe et al., 2002]. The concentrations of metals present in combustion wastewater tend to vary 

based on the type of fuel (e.g., coal) used by the plant. An important consideration in evaluating 

metals is their bioavailability–the proportion of total metals that can be incorporated into 

organisms. A metal’s bioavailability is affected by the characteristics of both the metal and 

surrounding environment (e.g., temperature, pH, salinity, oxidation-reduction (redox) potential, 

total organic content, suspended particulate content, and water velocity). Environmental 

conditions influence the tendency of a dissolved metal to remain in solution or precipitate out of 

solution, sorb to either organic or inorganic suspended matter in the water column, or sorb to the 

mixture of materials (e.g., clays and humic matter) found in sediments [U.S. EPA, 2007a]. 

Metals that precipitate out of solution can become concentrated in the sediments of a water body. 

While organisms can bioaccumulate metals by either consuming metal-enriched sediments and 

suspended particles or by filtering ambient water containing dissolved metals, organisms 

concentrate free metal ions from solution (i.e., dissolved metals) more efficiently than by 

consuming metal-enriched particulate matter [USGS, 1995]. Table 3-1 lists some of the common 

metals found in combustion wastewater that have been associated with documented health and 

environmental impacts or could potentially cause health and environmental impacts based on the 

loadings and concentrations present in the wastewater. Table 3-1 is intended to highlight the 

metals identified as pollutants of concern in combustion wastewater associated with health and 

environmental impacts and does not include all metals that may cause adverse impacts. Metals in 

steam electric industry wastewater are present in both soluble (i.e., dissolved) and particulate 

(i.e., suspended) form. Based on EPA sampling data collected in support of the proposed Steam 

Electric ELGs, some metals such as arsenic are present mostly in particulate form while other 

pollutants such as selenium and boron are present mostly in soluble form. The remainder of the 

section provides additional details on several key metals included in the EA. 
Section 3—Environmental And Human Health Concerns

3-4 

Table 3-1. Key Metals Found In Combustion Wastewater 

Pollutant Examples of Potential Health and Environmental Concerns

Aluminum Aluminum contamination can lead to the inability of fish to maintain the balance of their fluids and 

is associated with damage to amphibian eggs and larvae, mostly in areas under acid stress. Human 

exposure to high concentrations has been linked to Alzheimer’s Disease.

Arsenic a Arsenic contamination causes poisoning of the liver, developmental abnormalities, behavioral 

impairments, metabolic failure, reduced growth, and appetite loss in fish and is associated with an 

increased risk of cancer in humans in the liver and bladder.

Boron Leachate has caused ground water to exceed state drinking water standards for boron. Human 

exposure to high concentrations can cause nausea, vomiting, and diarrhea. Pollutant can be toxic to 

vegetation.

Cadmium Cadmium contamination can lead to developmental impairments in wildlife and skeletal 

malformations in fish. Human exposure to high concentrations can lead to kidney, liver, and lung 

failure. 

Chromium b Studies have found elevated chromium levels in ground water contaminated by leachate. Chromium 

is not known to bioaccumulate in fish; however, high concentrations of chromium can lead to gill 

damage, reduced growth, and altered metabolism in fish. Human exposure to high concentrations 

can cause gastrointestinal bleeding and lung problems.

Copper Copper contamination can lead to reproductive failure, gill damage, and reduced sense of smell in 

fish. Human exposure to high concentrations can cause nausea, vomiting, diarrhea, and liver and 

kidney damage.

Iron Leachate from combustion residuals stored in surface impoundments has caused elevated iron 

concentrations in nearby surface water. Iron contamination can lead to growth reduction, greater 

susceptibility to injury and disease, and decreased egg hatchability in fish. Human exposure to high 

concentrations can cause metabolic changes and damage to the pancreas, liver, spleen, and heart. 

Lead Leachate has caused ground water to exceed state drinking water standards for lead. Lead 

contamination can result in delayed embryonic development, suppressed reproduction, and 

inhibited growth in fish. Human exposure to high concentrations in drinking water can cause 

serious damage to the brain, kidneys, nervous system, and red blood cells.

Manganese Leachate has caused elevated manganese concentrations in nearby ground water and surface water. 

Manganese primarily accumulates in organisms lower in the food chain such as phytoplankton, 

algae, mollusks, and some fish. Although high levels can be toxic to humans, manganese is not 

generally considered toxic when ingested. The most common impacts due to human exposure to 

high concentrations involve the nervous system.

Mercury c The pollutant can convert into methylmercury, increasing the potential for bioaccumulation. 

Methylmercury contamination can lead to reduced growth and reproductive success in fish and 

invertebrates. Human exposure at levels above the MCL for relatively short periods can result in 

kidney and brain damage. Fetuses, infants, and children are particularly susceptible to impaired 

neurological development from methylmercury exposure.

Nickel At low concentrations, nickel can inhibit the growth of microorganisms and algae. Nickel toxicity 

in fish and aquatic invertebrates varies among species, and can damage the lungs, immune system, 

liver, and kidneys. Human exposure to high concentrations can cause gastrointestinal and kidney 

damage.

Selenium d Selenium readily bioaccumulates. Elevated concentrations have caused fish kills and numerous 

sublethal effects (e.g., organ damage, decreased growth rates, reproductive failure) to aquatic and 

terrestrial organisms. In humans, short-term exposure at levels above the MCL can cause hair and 

fingernail changes, damage to the peripheral nervous system, and fatigue and irritability. Long-term 

exposure can damage the kidney, liver, and nervous and circulatory systems. 

Thallium In humans, short-term exposure to thallium can lead to neurological symptoms, alopecia, 

gastrointestinal effects, and reproductive and developmental damage. Long-term exposures at levels 

above the MCL lead to changes in blood chemistry, and damage to liver, kidney, intestinal and 

testicular tissues, and hair loss.
Section 3—Environmental And Human Health Concerns

3-5 

Table 3-1. Key Metals Found In Combustion Wastewater 

Pollutant Examples of Potential Health and Environmental Concerns

Vanadium Vanadium contamination can lead to increased blood pressure and neurological effects in animals. 

There are very few reported cases of oral exposure to vanadium in humans; however, a few 

reported incidences documented diarrhea and stomach cramps. It also has been linked to the 

development of some neurological disorders and cardiovascular diseases. 

Zinc Zinc contamination leads to behavioral changes, reduced oxygen supply, and reproductive 

impairment in fish. In humans, short-term exposure can cause nausea, vomiting, and stomach 

cramps. Long-term exposure can cause anemia. 

a – Arsenic exists in two primary forms: arsenic III and arsenic V. 

b – Chromium exists in two primary forms: chromium III and chromium VI. 

c – The EA evaluated two forms of mercury: total mercury and methylmercury.

d – Selenium exists in two primary forms: selenium VI (selenate) and selenium IV (selenite).

Selenium 

Selenium is the most frequently cited pollutant associated with documented 

environmental impacts to ecological receptors following exposure to combustion wastewater

[NRC, 2006]. The toxic potential of selenium is related to its chemical form and solubility. The 

predominant chemical forms of selenium in 

aquatic systems that receive combustion 

wastewater discharges are selenite and selenate 

[Besser et al., 1996]. Availability of selenium is 

controlled by dissolved oxygen levels, hardness, 

pH, salinity, temperature, and the other chemical 

constituents present [NPS, 1997]. In alkaline 

conditions, selenite (Se(IV)) will oxidize in the 

presence of oxygen to become selenate (Se(VI)); 

selenate is both stable and soluble and is the 

commonly found form of the chemical in 

alkaline soils and waters. In acidic conditions, 

selenite is insoluble due to its tendency to bind 

to iron and aluminum oxides [WHO, 1987].

Because combustion wastewater may be 

alkaline or acidic, the form of selenium present 

in a particular waste stream depends on the type 

of fuel used, the fuel composition, and the 

amount of metal oxides present in the 

wastewater.

The extent to which selenium is found in ecological receptors is affected by 

bioaccumulation, biomagnification, and maternal transfer. Bioaccumulation occurs when an 

organism absorbs a toxic substance through food and exposure to the environment at a faster rate 

than the body can remove the substance. The bioaccumulation of selenium is of particular 

concern due to the potential for it to impact higher trophic levels through biomagnification 

[Coughlan and Velte, 1989] and offspring through maternal transfer [Hopkins et al., 2006; Nagle 

Metal Impacts to Ecological Receptors

• Due to bioaccumulation, seleniumrelated environmental impacts can linger 

for years even after exposure to 

combustion wastewater has ceased.

• Fish and invertebrates exposed to 

combustion wastewater have exhibited 

elevated mercury levels in their tissues 

and developed sublethal effects such as 

reduced growth and reproductive 

success.

• Elevated arsenic tissue concentrations 

are associated with several biological 

impacts such as liver tissue death, 

developmental abnormalities, and 

reduced growth. 
Section 3—Environmental And Human Health Concerns

3-6 

et al., 2001]. A laboratory study demonstrated that diet can be an important source of trace 

element exposure in aquatic snakes and potentially other amphibians [Hopkins et al., 2002]. 

Hopkins reported that the snakes accumulated significant concentrations of the trace elements, 

with selenium accumulation being the most notable. This study also revealed that amphibian 

prey species are able to migrate considerable distances and can therefore be exposed to toxic 

levels of selenium, even if they do not inhabit a contaminated site. Because of bioaccumulation 

and biomagnification, selenium-related environmental impacts can linger for years even after 

exposure to combustion wastewater has ceased [Rowe et al., 2002]. 

The primary selenium-related impacts observed by scientists include lethal effects such 

as fish kills; sublethal effects such as histopathological changes and damage to reproductive and 

developmental success; and the impacts of these effects on aquatic populations and communities. 

In a 1991 study, Sorensen found that dissolved selenium levels as low as 3 to 8 μg/L in aquatic 

environments can be life-threatening to fish [NPS, 1997]. Aquatic organisms exposed to 

combustion wastewater have exhibited elevated selenium concentration in organs such as their 

kidneys, liver, and gonads, resulting in abnormalities that hinder growth and survival [Rowe et 

al., 2002]. 

In addition to ecological impacts, EPA has documented numerous damage cases where 

selenium in combustion wastewater discharges resulted in fish consumption advisories being 

issued for surface waters and selenium MCLs being exceeded in ground water, suggesting that 

selenium concentrations in combustion wastewater have the potential to impact human health 

[NRC, 2006; U.S. EPA, 2007b]. Short-term exposure at levels above the MCL can cause hair 

and fingernail changes, damage to the peripheral nervous system, and fatigue and irritability in 

humans. Long-term exposure can damage the kidney, liver, and nervous and circulatory systems. 

For more information on lethal and sublethal effects of selenium, refer to the selenium discussion 

in Section 5.1. 

Mercury 

Mercury is a volatile metal and highly 

toxic compound that represents an environmental 

and human health threat even in small 

concentrations. One of the primary environmental 

concerns regarding mercury concentrations in 

combustion wastewater is the potential for 

methylmercury to form in combustion residuals 

surface impoundments and constructed wetlands 

prior to discharge and in receiving waters 

following discharge. Methylmercury is an organic 

form of mercury that readily bioaccumulates in 

fish and other organisms and is associated with 

high rates of reproductive failure [WHO, 1976]. 

Bacteria found in anaerobic conditions, such as 

those that may be present in sediments found on 

the bottom of combustion residuals surface 

impoundments or in river sediments, convert 

Metal Impacts to Human Receptors

• Pregnant women exposed to mercury 

can pass the contaminant to their 

developing fetus, leading to possible 

mental retardation and damage to 

other parts of the nervous system.

• Inorganic arsenic is a carcinogen 

(i.e., causes cancer). Cadmium is a 

suspected carcinogen. 

• Human exposure to high 

concentrations of lead in drinking 

water can cause serious damage to 

the brain, kidneys, nervous system, 

and red blood cells, especially in 

children.
Section 3—Environmental And Human Health Concerns

3-7 

mercury to methylmercury through a process called methylation [WHO, 1976]. Microbial 

methylation rates increase in acidic and anoxic environments with high concentrations of organic 

matter. Sublethal effects from mercury exposure include reduced growth and reproductive 

success, metabolic changes, and abnormalities of the liver and kidneys. Human exposure at 

levels above the MCL for relatively short periods of time can result in kidney and brain damage. 

Pregnant women who are exposed to mercury can pass the contaminant to their developing fetus, 

leading to possible mental retardation and damage to other parts of the nervous system [ATSDR, 

1999]. Studies have documented fish and invertebrates exposed to mercury from combustion 

wastewater exhibiting elevated levels of mercury in their tissues and developing sublethal effects 

such as reduced growth and reproductive success [Rowe et al., 2002]. 

Arsenic

Arsenic, like selenium, is of concern because it is soluble in near-neutral pH and in 

alkaline conditions, which are commonly associated with combustion wastewater. Therefore,

arsenic is highly mobile and is frequently observed at elevated concentrations at sites located 

downstream from combustion residuals surface impoundments [NRC, 2006]. Inorganic arsenic, a 

carcinogen (i.e., causes cancer), is found in natural and drinking waters mainly as trivalent 

arsenite (As(III)) or pentavalent arsenate (As(V)) [WHO, 2001]. Both the arsenite and arsenate 

forms are highly soluble in water. 

Arsenic is also of concern due to its tendency to bioaccumulate in aquatic communities 

and potentially impact higher-trophic-level organisms in the area. For example, studies have 

documented water snakes, which feed on fish and amphibians, with arsenic tissue concentrations 

higher than their prey [Rowe et al., 2002]. Elevated arsenic tissue concentrations are associated 

with several biological impacts such as liver tissue death, developmental abnormalities, 

behavioral impairments, metabolic failure, reduced growth, and appetite loss [NRC, 2006; Rowe 

et al., 2002, U.S. EPA 2011f]. 

Human exposure to arsenic will likely occur through ingesting contaminated drinking 

water [WHO, 2001]. Exposure can also occur by consuming contaminated fish; however, several 

studies have shown that most arsenic in fish is organic and not harmful to humans. Inorganic

arsenic, which can cause cancer in humans, typically makes up less than 4 percent of the total 

arsenic that accumulates in fish [U.S. EPA, 1997b]. 

EPA has documented several damage cases where arsenic levels exceeded drinking water 

standards in ground water near combustion residuals surface impoundments [U.S. EPA, 2007b]. 

Arsenic contamination of ground water at the levels documented represents a potential human 

health threat, if either the aquifer is used as a drinking water source or the ground water 

contaminates a downstream drinking water source. 

Cadmium 

The speciation and toxicity of cadmium in water depends on the water’s salinity, 

hardness, temperature, and organic content [WHO, 1992]. Cadmium tends to bioaccumulate 

readily in mollusks, soil invertebrates, and microorganisms. Due to its chemical similarity with 

calcium, it can also interfere with calcium uptake in aquatic organisms, which can lead to 
Section 3—Environmental And Human Health Concerns

3-8 

sublethal effects in fish such as skeletal malformation. Divalent cadmium (Cd(II)) is the species 

most commonly found in an aquatic environment, but depending on the quality of the water, 

cadmium can also occur as cadmium carbonate, hydroxide, sulfite, sulfate or chlorides. 

Cadmium is a probable or suspected carcinogen [ATSDR, 2008a]. In humans, chronic 

low-level exposure to cadmium from contaminated drinking water can lead to cadmium 

poisoning, which is primarily associated with failure of the kidney and liver, but may also impact 

the lungs. 

Thallium 

Thallium typically exists as the monovalent or trivalent thallium ion [WHO, 1996]. It is 

soluble in most waters and is readily available to aquatic life. Bioconcentration factors are high 

for fish and vegetation in fresh and marine waters, as well as marine invertebrates, which 

suggests that thallium may be a potential threat to higher order organisms in vulnerable 

ecosystems [U.S. EPA, 2011a]. Studies in humans and animals indicate that thallium compounds 

are readily absorbed through ingestion of food and water and maternal transfer [WHO, 1996]. 

Thallium can accumulate in the hair and bone; however, studies often observed the 

highest concentrations in the endocrine glands, kidneys, liver, and intestine [WHO, 1996]. 

Elevated thallium concentrations can lead to neurological symptoms (e.g., weakness, sleep 

disorders, muscular problems), alopecia (i.e., loss of hair from the head and body), and 

gastrointestinal effects (e.g., diarrhea and vomiting). Long-term exposures at levels above the 

MCL lead to changes in blood chemistry; damage to liver, kidney, and intestinal and testicular 

tissues; and hair loss. Thallium exposure can also lead to reproductive and developmental 

damage [U.S. EPA, 2009a]. 

Lead

Neither metallic lead nor many of its common mineral forms are soluble in water, 

although it can be soluble in some acids or water with low pH; thus, lead is commonly present in 

precipitate form in water. Therefore, combustion wastewater may initially have high 

concentrations of lead, but later sampling of the wastewater can show decreased concentrations 

because the lead settles out quickly. Lead will accumulate in aquatic organisms, but 

bioconcentration factors can cover a wide range and depend on the species. Studies have shown 

lead to cause delayed embryonic development and suppressed reproduction and inhibition of 

growth rate among fish, crab, and several other aquatic organisms [U.S. EPA, 1984]. Human 

exposure to high concentrations of lead in drinking water can cause serious damage to the brain, 

kidneys, nervous system, and red blood cells, especially in children. 

Boron 

Boron is primarily found in the environment combined with oxygen in compounds called 

borates [ATSDR, 2010b]. Boron concentrations in North American waters are typically below 

0.1 milligrams per liter (mg/L) [WHO, 1998], although areas with natural boron-rich deposits 

may have ground water levels as high as 300 mg/L [ATSDR, 2010b]. The World Health 

Organization (WHO) suggests that the potential of adverse effects of boron on the aquatic 

ecosystem is low because the no-effect concentration (1 mg/L) is much greater than levels found 
Section 3—Environmental And Human Health Concerns

3-9 

in the ambient environment. Boron does not magnify through the food chain, but does 

accumulate in aquatic and terrestrial plants. While it is an essential micronutrient for higher 

plants, there is a small range between deficiency and toxicity in some plants. Studies of acute 

exposure to fish yielded toxicity values ranging from approximately 10 to 300 mg/L. Rainbow 

trout and zebra fish were the most sensitive. Mallard duckling growth was impacted at dietary 

levels of 30 and 300 milligrams per kilogram (mg/kg), while survival was reduced at 1,000 

mg/kg [WHO, 1998]. 

EPA has not set a numerical criterion under the NRWQC for aquatic life, but it has issued 

a narrative criterion of 750 μg/L for sensitive crops that receive long-term irrigation.

EPA has not set a NRWQC for human health. Very few human studies have examined 

health effects resulting from boron exposure through oral ingestion. However, one study 

documents nausea, vomiting, and diarrhea in an adult male who ingested 85 mg/kg of boron (30 

g as boric acid) [ATSDR, 2010b]. In addition, animal experiments indicate that boron in the form 

of boric acid and borate affect reproductive and developmental processes at levels that are 

approximately 100 to 1,000 times greater than normal exposure levels, approximately 1.2 

milligrams per day (mg/day) [WHO, 1998]. 

Manganese 

Manganese is a constituent in coal and other fuels, where it is usually—depending on the 

type of coal—present at a higher concentration than other metals. Looking at a range of coal 

types (bituminous, subbituminous, and lignite) from across the country, the manganese 

concentration in coal ranges from 5.65 micrograms per gram (μg/g) in subbituminous coal from 

Wyoming to 259 μg/g in bituminous coal from Iowa. For comparison, the selenium 

concentrations in these coals are 0.51 and 3.6 μg/g, respectively [U.S. EPA, 2000c]. 

In water, manganese tends to attach to particles or settle into the sediment [ATSDR, 

2008b]. It occurs in both dissolved and suspended forms, depending on the water chemistry (e.g., 

pH) [WHO, 2011]. Manganese can bioaccumulate in lower organisms, such as phytoplankton, 

algae, mollusks, and some fish, but not in higher organisms. Studies suggest that 

biomagnification up the food chain is not significant [ATSDR, 2008b]. 

Due to a high bioaccumulation factor and concentrations in the edible portions of 

mollusks, there is a criterion to protect the consumers of marine mollusks—100 μg/L for marine 

waters [U.S. EPA, 1986]. Although high levels can be toxic to humans, manganese is an 

essential nutrient required to maintain health and is generally not considered to be toxic when 

ingested [WHO, 2011]. EPA did not set a primary MCL for manganese in drinking water; 

however, EPA did set secondary (nonenforceable) standards at 50 μg/L to minimize 

objectionable qualities in the drinking water that lead to laundry stains and objectionable tastes in 

beverages.

3.1.2 Nutrients

Nutrients (e.g., phosphorus and nitrogen) are essential components for plants and animals 

to grow and develop; however, increased nutrient concentrations can upset the delicate balance 

of nutrient supply and demand required to maintain aquatic life in surface waters. For example, 
Section 3—Environmental And Human Health Concerns

3-10 

excess nutrients is one factor causing low oxygen in surface waters (hypoxia) and hazardous 

algal blooms. These are primarily problems for estuaries, such as the Chesapeake Bay, and 

coastal waters, such as the Gulf of Mexico. Nutrient concentrations present in combustion 

wastewater are primarily attributed to the fuel composition and air pollution controls in the 

combustion process. 

EPA estimates that annual nutrient loadings from the steam electric industry are currently

30.4 million pounds of total nitrogen and 682,000 pounds of phosphorus. Total nitrogen loadings 

from coal-fired power plants could potentially increase significantly in the future as air pollution 

limits become stricter and air pollution control use increases. While the current concentration of 

nitrogen in combustion wastewater from an individual power plant can be relatively low, the 

total nitrogen loadings from a single plant can be significant due to high wastewater discharge 

flow rates. Total nutrient loadings from multiple power plants is especially a concern on water 

bodies that are nutrient impaired or in watersheds that contribute to downstream nutrient 

problems. High nutrient loadings to receiving waters can affect the ecological stability of 

freshwater and saltwater aquatic systems; excessive levels of nutrients can stimulate plant and 

algal growth that can obstruct sunlight penetration, increase turbidity, and lead to declining 

dissolved oxygen levels. These aquatic changes can potentially kill bottom-dwelling aquatic 

plants. 

3.1.3 TDS 

TDS, a reflection of water’s salinity level, is a measure of the amount of dissolved matter 

in water. TDS is comprised of primarily inorganic salts, as well as a small amount of organic 

matter. Common inorganic salts that can be found in water include cations (positively charged 

ions): calcium, magnesium, potassium and sodium; and anions (negatively charged ions): 

carbonates, nitrates, bicarbonates, chlorides, and sulfates. TDS concentrations in steam electric 

industry wastestreams include contributions from dissolved metals, chlorides, and bromides. 

Dissolved metals and other TDS constituents are found in wastewater particularly at acidic pH 

levels when they exhibit high solubilities. Negative impacts from TDS in combustion wastewater 

is attributable to the specific constituents that comprise the TDS in the discharge.

Bromides 

Bromide is the anion of bromine; it commonly exists as salts with potassium and other 

cations, which are usually very soluble in water. It is commonly found in nature, with levels 

ranging from trace amounts to 0.5 mg/L in fresh water to 65 mg/L in seawater. The bromide ion 

has a low degree of toxicity, and animal testing suggests very low acute toxicity upon oral 

administration; accordingly, bromide is not of toxicological concern to humans [WHO, 2009]. 

While bromide itself is not thought to be toxic at levels present in the environment, its 

reaction with other constituents may be cause for concern. The bromide ion can form bromated, 

a disinfection byproduct (DBP), when drinking water plants use ozone to disinfect the source 

water. Bromide can also react with chlorine or chlorine-based disinfectants and naturally 

occurring organic matter in water to form brominated and mixed chloro-bromo DBPs, such as 

trihalomethanes or halogenated acetic acids [WHO, 2009]. EPA has set MCLs for DBPs: 
Section 3—Environmental And Human Health Concerns

3-11 

• 0.010 mg/L for bromated due to increased cancer risk from long-term exposure; 

• 0.060 for haloacetic acids (HAAs) due to increased cancer risk from long-term 

exposure; and 

• 0.080 mg/L for total trihalomethanes (TTHMs) due to increased cancer risk and liver, 

kidney or central nervous system problems from long-term exposure [U.S. EPA, 

2009e]. 

Studies indicate that exposure to TTHMs and other DBPs from chlorinated water are 

associated with human bladder cancer [Villanueva et. al., 2004; Cantor et. al., 2010]. DBP 

formation is influenced by factors such as bromide ion concentration, pH of the source water, the 

disinfectant dose (ozone or chlorine), reaction or contact time, and organic matter concentration 

and reactivity [Lin and Singer, 2003]. 

The city of Pittsburgh, in cooperation with the University of Pittsburgh, is currently 

conducting a study on the Allegheny River to determine the major sources of bromide 

discharges, including coal-fired power plants. Typically, bromide concentrations are very low in 

the river, but there are increased levels near industrial sites. EPA is currently examining the 

effects of bromide concentration on TTHMs to determine an acceptable level of bromide in a 

water body [U.S. EPA, 2012a]. Drinking water utilities are concerned as well, noting that the 

bromide concentrations have made it increasingly difficult for them to meet Safe Drinking Water 

Act requirements for TTHMs [U.S. EPA, 2012a]. 

Chlorides 

Chloride levels in combustion wastewater are 

dependent upon chlorine concentrations present in the 

parent coal as well as the amount of recirculation in 

the FGD system. FGD systems with many iterations 

of circulation between blowdown cycles exhibit high 

concentrations of chlorides. In addition, studies have 

found that combustion wastewater leachate reaching 

ground water has caused chloride levels to exceed secondary MCLs [NRC, 2006]. Chlorides 

contribute to the high TDS levels typical of combustion wastewater, as do calcium and 

magnesium. Both chloride and TDS levels affect the availability and toxicity of other 

combustion wastewater constituents, including metals. As TDS and chloride levels fluctuate, so 

do the amounts of other metals that dissolve due to solubility characteristics.

EPA recommends the following for chloride: criterion maximum concentration of 

860 mg/L (acute effects) and criterion continuous concentration of 230 mg/L (chronic effects) 

[U.S. EPA, 2009d]. Exceeding these chloride levels in wastewater discharges can be harmful to 

animals and plants in non-marine surface waters and can disrupt ecosystem structure. It can also 

adversely affect biological wastewater treatment processes. Furthermore, excessively high 

chloride concentrations in surface waters can impair their use as source waters for potable water 

supplies. If sodium is the predominant cation present, the water will have an unpleasant taste due 

to the corrosive action of chloride ions. 

Pollutant Loadings from Steam 

Electric Power Plants

• 5,500,000,000 pounds of pollutants 

per year.

• 8,300,000 pounds of toxicweighted pound equivalents 

(TWPE) per year.
Section 3—Environmental And Human Health Concerns

3-12 

3.2 LOADINGS ASSOCIATED WITH COMBUSTION WASTEWATER 

As discussed above, the pollutants commonly found in combustion wastewater such as 

metals, nutrients and TDS (including bromides and chlorides) can cause considerable harm to 

surface waters, aquatic life, wildlife, and human health. The total pollutant loadings from steam 

electric power plants are significant with the steam electric power sector accounting for at least 

50 to 60 percent of the toxic pollutants reported to be discharged in industrial National Pollutant 

Discharge Elimination System (NPDES) permits [ERG, 2012g]. EPA estimated the amount of 

pollutants (i.e., loadings) discharged by steam electric power plants throughout the United States 

as over 8 million toxic weighted pound equivalents (TWPE)4 annually in the waste streams 

evaluated and considered as part of the revision to the Steam Electric ELGs. When coupled with 

the types of impacts associated with the pollutants, the amount of the loadings raises concern 

about the risks that these discharges present to the aquatic environment and the surrounding 

ecosystem. This section presents the annual baseline (i.e., current) pollutant loadings associated 

with the evaluated waste streams and compares steam electric discharges to those of other 

industries to provide perspective on the magnitude of the loadings and subsequent potential 

impact these waste streams pose to the environment. In addition, this section discusses the 

Chesapeake Bay and Great Lakes as example sensitive environments that receive substantial 

pollutant loadings from steam electric power plant discharges. 

3.2.1 Annual Baseline Pollutant Loadings 

As part of its effluent guidelines development process, EPA estimated the pollutant 

loadings discharged from steam electric power plants for the evaluated waste streams, as 

described in Section 10 of the TDD. Table 3-2 presents the baseline annual pollutant loadings 

discharged for select pollutants considered for analysis in the EA.5 EPA presents these loadings 

in terms of pounds and TWPE and lists the TWF where applicable. The pollutants with the 

highest annual TWPE discharges are arsenic, boron, cadmium, manganese, mercury, and 

selenium. Although the total pounds discharged of arsenic, cadmium, and mercury are lower than 

other pollutants, their relative toxicity (as represented by the TWF) result in a large TWPE. 

Other pollutants, such as boron and manganese, are relatively low in toxicity but due to the 

relatively high amount of these pollutants in the combustion wastewaters, their resulting TWPE 

is high. The high TWPE for selenium results from a combination of its quantity discharged in 

combustion wastewaters and its TWF. 

 

4 To calculate the TWPE, EPA multiplies a mass loading of a pollutant in pounds per year (lb/yr) by a pollutantspecific weighting factor, called the toxic weighting factor (TWF), to derive a "toxic-equivalent" loading (lbequivalent/yr), or TWPE. TWFs account for differences in toxicity across pollutants and provide the means to 

compare mass loadings of different pollutants on the basis of their toxic potential. EPA has developed TWFs for 

more than 1,900 pollutants based on aquatic life and human health toxicity data, as well as physical/chemical 

property data [U.S. EPA, 2006a].

5 Almost half of the 8 million TWPE discharged in the evaluated waste streams is from additional pollutants not 

presented in Table 3-2. For the EA, EPA focused on the pollutants listed in the table due to a number of factors: 

metal is present in the evaluated waste streams (see Table 2-1), elevated levels have been observed in surface waters 

or wildlife from exposure to combustion wastewater, and amount of the individual pollutant loadings to receiving 

waters. See the TDD for a complete listing of baseline pollutant loadings. 
Section 3—Environmental And Human Health Concerns

3-13 

Table 3-2. Annual Baseline Pollutant Discharges from the Steam Electric Industry 

Pollutant a TWF b

Annual Discharge, 

pounds (lbs)

Annual TWPE, poundequivalent (lb-eq)

Metals

Manganese 0.07043 14,500,000 1,020,000

Cadmium 23.1168 31,900 738,000

Boron 0.00834 54,300,000 453,000

Mercury 117.118 2,820 330,000

Arsenic 4.0413 79,200 320,000

Selenium 1.1213 225,000 252,000

Thallium 1.0271 164,000 168,000

Lead 2.24 64,400 144,000

Aluminum 0.0647 1,970,000 128,000

Copper 0.6348 69,900 44,400

Nickel 0.1089 287,000 31,200

Iron 0.0056 4,990,000 27,900

Zinc 0.0469 393,000 18,400

Chromium VI 0.5166 11,800 6,090

Vanadium 0.035 158,000 5,530

Total Metals c 1,790,000,000 4,800,000

Nutrients

Total Nitrogen Not applicable 30,400,000 Not applicable

Total Phosphorus Not applicable 682,000 Not applicable

Other

Chlorides 2.435 X 10-05 1,640,000,000 39,800

Total Pollutants c,d 5,500,000,000 8,320,000

Sources: ERG, 2013c; U.S. EPA, 2006a.

a – The list of pollutants included in this table is only a subset of pollutants included in the loadings analysis (see 

Section 10 of the TDD).

b –TWFs for the following metals apply to all metal compounds: arsenic, chromium, copper, lead, manganese, 

mercury, nickel, selenium, thallium, vanadium, and zinc. EPA updated TWFs for boron, chlorides, chromium 

compounds, and iron for the Steam Electric ELGs pollutant loadings analysis.

c – To avoid double-counting of dissolved metals, the totals include all pollutants from the loadings analysis with 

the exception of TDS. Annual baseline discharges of TDS from the evaluated waste streams total approximately 

7,120,000,000 pounds.

d – The totals represent the pollutant loadings in discharges of the evaluated waste streams – specifically, FGD 

wastewater, fly ash transport wastewater, bottom ash transport wastewater, and leachate (see Section 10 of the 

TDD).
 

 

 

 

 

 

 

 

 

 

 

Section 3—Environmental And Human Health Concerns 

3.2.2 Comparison of Steam Electric Loadings to Other Industries 

The total TWPE discharges from the steam 

electric industry are higher than the TWPEs estimated 

for many other industries. As part of the Preliminary 

2010 Plan published on October 30, 2009 (74 FR 

68599), EPA identified 10 point source categories, out 

of 56 categories, that represented the bulk of the 

estimated toxic wastewater discharges (as measured 

by TWPE) from existing industrial point source 

categories. EPA ranked each point source category by 

the amount of toxic pollutants in its discharges and 

identified the Steam Electric Power Generating Point 

Source Category (40 CFR 423) as the category with 

the highest TWPE. Table 3-3 presents the total TWPE estimated as part of the 2010 Effluent 

Guidelines Planning Process for the remaining nine point source categories with the highest 

TWPE [U.S. EPA, 2011d]. EPA estimated that the total baseline TWPE from combustion 

wastewater (see Table 3-2) is over eight times the amount estimated for the pulp, paper, and 

paperboard industry and petroleum refining industry (second and third highest ranking) and over 

10 times the TWPE for seven of the eight other industries identified as the top TWPE dischargers 

in the Final 2010 Plan [U.S. EPA, 2011d].6 This suggests that the loadings from the subset of 

evaluated waste streams represent a greater environmental concern within the context of all 

industrial dischargers across the United States. 

Table 3-3. Pollutant Loadings for the Final 2010 Effluent Guidelines Planning Process: 

Top 10 Point Source Categories
 

Pollutant Loadings: How Does the 

Steam Electric Industry Compare? 

EPA estimates that discharges from 

steam electric power plants alone 

contribute at least 50 to 60 percent of 

the toxic weighted pound equivalent 

(TWPE) pollutant loadings to the 

environment among all industrial 

categories that report discharges under 

NPDES permits. 

40 CFR Part Point Source Category 

Total TWPE 

(lb-eq/yr) 

423 Steam Electric Industry 8,320,000 a 

430 Pulp, Paper And Paperboard 1,030,000 

419 Petroleum Refining 1,030,000 

421 Nonferrous Metals Manufacturing 994,000 

418 Fertilizer Manufacturing 826,000 

414 Organic Chemicals, Plastics And Synthetic Fibers 649,000 

440 Ore Mining And Dressing 448,000 

415 Inorganic Chemicals Manufacturing 299,000 

444 Waste Combustors 254,000 

410 Textile Mills 250,000 

Source: U.S. EPA, 2011d. 

a – As presented in Table 3-2, EPA calculated the Steam Electric Industry (40 CFR 423) discharges for the proposed 

ELGs analysis to total 8,320,000 TWPE annually. 

6 Data sources for the other industry discharges include Discharge Monitoring Reports (DMRs) and Toxic Release 

Inventory (TRI) reports. EPA recognizes that the DMR and TRI data have limitations (e.g., only a subset of facilities 

and a subset of pollutants might be included in the estimated loadings); however, these are the most readily available 

data sets that represent discharges across the United States. 

3-14
 
Section 3—Environmental And Human Health Concerns

3-15 

3.2.3 Comparison of Steam Electric Loadings to Publicly Owned Treatment Works

To provide additional perspective on the magnitude of the pollutant loadings from steam 

electric power plants, EPA compared loadings for the evaluated waste streams to those of an 

average publicly owned treatment works (POTW). EPA selected POTWs for comparison 

because, for point sources, POTWs and steam electric plants dwarf all other point source 

discharges in terms of total TWPE of metals discharged to waters in the United States [U.S. 

EPA, 2010c].7 In addition, the over 16,000 POTWs are located across the United States, are 

known to have consistent wastewater influent characteristics, and are a common metric used for 

point source evaluations. 

EPA calculated the average pollutant loadings discharged from a typical POTW using 

EPA’s Effluent Guidelines Program Plan DMR database, DMRLoadsAnalysis2009_v02.mdb. 

EPA assumed a typical POTW to discharge wastewater at a rate of 3 to 5 million gallons per day 

(MGD)8

 based on the number of facilities by discharge flow rate reported in Metcalf and Eddy, 

2003 [ERG, 2012c]. EPA developed queries in the DMRLoadsAnalysis2009_v02.mdb to 1) 

select POTWs that discharge between 3 and 5 MGD and 2) calculate the average DMR loadings 

(in pounds and TWPE per year) for each pollutant [ERG, 2012c]. Table 3-4 compares the 

average steam electric pollutant loadings by waste stream to the pollutant loadings from an 

average POTW assumed to discharge 3 to 5 MGD. The results of the analysis demonstrate the 

following: 

• Average FGD wastewater discharges contain more than 250 times more boron and 

over 300 times more manganese.

• Average FGD wastewater discharges contain more than 80 times more selenium.

 

7 Based on metal loadings (total TWPE) calculated by EPA’s DMR Pollutant Loading Tool, 2010 data, by Standard 

Industrial Classification (SIC) code. The top two industries are SIC 4952 – sewerage systems (i.e., POTWs) and SIC 

4911 – electrical services.

EPA’s DMR Pollutant Loading Tool is an online tool (http://cfpub.epa.gov/dmr/) that calculates pollutant loadings 

from permit and DMR data from EPA‘s Permit Compliance System (PCS) and Integrated Compliance Information 

System for the National Pollutant Discharge Elimination System (ICIS-NPDES). The tool also ranks dischargers, 

industries, and watersheds based on pollutant mass and toxicity, and presents “top 10” lists to help users determine 

which facilities and industries are producing these discharges and which watersheds are impacted. Facilities report 

pollutant discharge monitoring data in their DMR as mass-based quantities (e.g., pounds per day) and/or 

concentrations (e.g., mg/L). The DMR Pollutant Loading Tool allows users to gather annual loadings data. For this 

EA, EPA reviewed the 2010 loadings reported in DMRs. 

The use of the DMR data has its limitations. Only pollutants included in the facility’s NPDES permit are included in 

the PCS and ICIS-NPDES databases; therefore, if a facility does not have mercury limitations, mercury discharges 

from that facility will not be included in the total for industrial discharges. States (or other permitting authority) have 

some discretion as to which data they make available (or enter) to PCS and ICIS-NPDES. For example, permitting 

authorities enter DMR and permit information for facilities that are considered major dischargers. However, they do 

not necessarily enter DMR or permit information into PCS for minor dischargers or facilities covered by a general 

permit. 

8 For comparison, the average discharge flow rate for the steam electric waste streams of concern are 0.5 MGD for 

FGD wastewater; 2.4 MGD for fly ash sluice water; 1.8 MGD for bottom ash sluice water; and 0.06 MGD for 

leachate (U.S. EPA, 2012b).
Section 3—Environmental And Human Health Concerns

3-16 

• Average FGD wastewater discharges contain more than 30 times more cadmium and 

nickel. 

• Loadings in fly ash transport water have more than 10 times more arsenic, boron, 

cadmium, manganese, and selenium. 

• Loadings in fly ash transport water have 30 times more thallium. 

• Loadings in the bottom ash transport water have 40 times more thallium.

• Loadings in the bottom ash transport water have over 10 times more nickel. 

• Only boron, iron, manganese, and selenium in the average leachate wastewater 

discharges showed higher loadings than the average POTW. 

Nutrient loadings (total nitrogen and total phosphorus) from the average steam electric 

waste streams of concern are similar in magnitude to the nutrient loadings from an average 

POTW. Total nitrogen loadings from an average FGD waste stream are similar to those of an 

average POTW. Nitrogen loadings from average fly 

ash and bottom ash transport waters are each 

equivalent to about one-third the amount of total 

nitrogen from an average POTW. The amount of total 

phosphorus discharged by an average POTW is 10 to 

30 times higher than that in the average FGD 

wastewater, fly ash transport water, and bottom ash 

transport water discharges. EPA did not calculate 

nutrient loadings for leachate. 

For chlorides, EPA found that average FGD 

wastewater discharges contain approximately 8 times 

greater chloride loadings than an average POTW 

discharge. The average discharge of fly ash transport 

water, bottom ash transport water, and leachate 

wastewater from a steam electric power plant 

contains less chlorides than a typical POTW 

discharge. EPA’s DMR data did not include pollutant 

loadings for TDS from POTWs; therefore, EPA could 

not compare these pollutant loadings between steam 

electric and POTW discharges. 

To provide additional perspective on the magnitude of the loadings, EPA calculated the 

equivalent number of typical POTWs that would discharge loadings equal to the 290 steam 

electric power plants included in the baseline loadings analysis. Table 3-5 presents total pollutant 

loadings for the waste streams of concern (for the 290 plants) and the number of typical POTWs 

that would discharge equivalent loadings. The results demonstrate that the magnitude of the total 

loadings from 290 steam electric power plants is equivalent to a significantly larger number of 

typical POTWs for many of the pollutants commonly known to cause environmental harm. For 

example, EPA estimated that combustion wastewaters from the 290 steam electric power plants 

discharge loadings equivalent to over 10,000 POTW discharges of boron, manganese, selenium, 

and thallium, and over 1,000 POTW discharges of arsenic, cadmium, iron, lead, nickel and 

Steam Electric Industry Loadings 

Compared to POTWs

• FGD wastewater discharges 

contain 

- 300 times more manganese

- 250 times more boron 

- 80 times more selenium

- 30 times more nickel

- 30 times more cadmium 

• Bottom ash transport water 

discharges contain 40 times more 

thallium and over 10 times more 

nickel. 

• Fly ash transport water discharges 

contain 10 times more arsenic, 

boron, cadmium, manganese, and 

selenium and 30 times more 

thallium.
Section 3—Environmental And Human Health Concerns

3-17 

chlorides. This suggests that, for the evaluated waste streams, 290 steam electric plants 

contribute substantial pollutant loadings to the environment, even when compared to over 50,000 

POTWs in the United States.

 
3-18

Section 3—Environmental And Human Health Concerns

Table 3-4. Comparison of Average Pollutant Loadings in the Evaluated Waste Streams to an Average POTW

Pollutant

Average Plant FGD 

Discharge a,b

Average Plant Fly Ash 

Discharge a,c

Average Plant Bottom 

Ash Discharge a,d

Average Plant 

Leachate Discharge a,e

Average POTW

Discharge a,f

Loadings 

(lbs/yr)

TWPE

(lb-eq/yr)

Loadings 

(lbs/yr)

TWPE (lbeq/yr)Loadings 

(lbs/yr)

TWPE 

(lb-eq/yr)

Loadings 

(lbs/yr)

TWPE

(lb-eq/yr)

Loadings 

(lbs/yr)

TWPE 

(lb-eq/yr)

Aluminum 2,500 162 7,660 495 2,220 144 1,110 71.9 3,590 215

Arsenic 10.1 40.9 479 1,940 69 279 11.1 44.7 46 186

Boron 410,000 3,420 18,900 158 8,330 69.5 4,780 39.8 1,540 13

Cadmium 133 3,070 58.6 1,350 30.5 705 0.594 13.7 4 82

Chromium VI 6.7 3.46 77.6 40.1 7.95 4.11 (g) (g) 18 9

Copper 26.1 16.6 280 178 113 72 2.11 1.34 154 97

Iron 1,850 10.4 5,850 32.7 8,610 48.2 15,100 84.4 2,530 14

Lead 5.93 13.3 206 461 134 299 0.335 0.751 49 109

Manganese 115,000 8,090 3,680 259 680 47.9 1,050 74.2 354 25

Mercury 6.58 771 8.65 1,010 3.33 390 0.26 30.4 3,180 372,000

Nickel 1,030 112 239 26.1 451 49.1 16.6 1.81 31 3

Selenium 1,490 1,670 257 289 44.7 50.2 20.5 23 18 21

Thallium 19.3 19.8 300 308 427 439 0.359 0.369 10 10

Vanadium 25.9 0.908 428 15 50.7 1.77 876 30.7 no data no data

Zinc 1,630 76.7 790 37 338 15.9 40.1 1.88 453 18

Total Nitrogen 109,000 - 39,000 - 39,400 - (g) - 123,000 -

Total Phosphorus 651 - 1,810 - 1,320 - (g) - 17,800 -

Chlorides 12,800,000 311 265,000 6.46 187,000 4.55 155,000 3.78 1,610,000 -

TDS 44,100,000 - 3,690,000 - 4,350,000 - 993,000 - no data no data

a – All values are rounded to three significant figures.

b – Average FGD loadings based on 117 plants assumed to discharge FGD wastewater under baseline conditions [ERG, 2013c]. 

c – Average fly ash loadings based on 93 plants assumed to discharge fly ash sluice under baseline conditions [ERG, 2013c]. 

d – Average bottom ash loadings based on 244 plants assumed to discharge bottom ash sluice under baseline conditions [ERG, 2013c]. 

e – Average leachate loadings based on 102 plants assumed to discharge leachate under baseline conditions [ERG, 2013c]. 

f – Average POTW loadings based on average loadings calculated by DMRLoadsAnalysis2009_v02.mdb (DCN SE01961) for POTWs discharging 3 to 5 MGD 

of wastewater. 

g – EPA did not calculate loadings for this pollutant and waste stream. See Section 10 of the TDD.
Section 3—Environmental And Human Health Concerns

3-19 

Table 3-5. Estimated Number of POTW Equivalents for Total Pollutant Loadings from the 

Evaluated Waste Streams

Pollutant

Annual Discharge

pounds (lbs) a

Equivalent Number of Average 

POTWs b

Aluminum 1,970,000 550

Arsenic 79,200 1,720

Boron 54,300,000 35,300

Cadmium 31,900 7,980

Chromium VI 11,800 655

Copper 69,900 454

Iron 4,990,000 1,970

Lead 64,400 1,320

Manganese 14,500,000 41,000

Mercury 2,820 <1

Nickel 287,000 9,250

Selenium 225,000 12,500

Thallium 164,000 16,400

Vanadium 158,000 No values for comparison

Zinc 393,000 868

Total Nitrogen 30,400,000 247

Total Phosphorus 682,000 38

Chlorides 1,640,000,000 1,020

TDS 7,120,000,000 No values for comparison

a – ERG, 2013c. 

b – Equivalent number of POTWs is estimated by dividing the total annual pollutant loadings by the average POTW 

loadings presented in Table 3-4 for a 4-MGD POTW.

3.2.4 Pollutant Loadings to the Chesapeake Bay Watershed 

Most of the Chesapeake Bay and its tidal 

waters are listed as impaired for excess nitrogen, 

phosphorus, and sediment. These pollutants cause 

oxygen-consuming algae blooms and create “dead 

zones” where fish and shellfish cannot survive, 

block sunlight that is needed for underwater 

grasses, and smother aquatic life on the bottom of 

the Bay. To restore water quality in the Bay, EPA 

established Total Maximum Daily Load (TMDL) 

limits for the Chesapeake Bay watershed in 

December 2010. These limits are of 186 million pounds of nitrogen, 12.5 million pounds of 

phosphorus, and 6.45 billion pounds of sediment each year, reducing the discharges to the 

watershed by 25 percent for nitrogen, 24 percent for phosphorus, and 20 percent for sediment. 

Pollutant loadings to the Chesapeake Bay watershed come from both point sources and nonpoint 

sources. Point sources include municipal wastewater facilities, industrial discharge facilities

(e.g., steam electric power plants and concentrated animal feeding operations), National 

Pollutant Discharge Elimination System (NPDES) permitted stormwater (municipal separate 

storm sewer systems (MS4) and construction and industrial sites), and other sources. Nonpoint 

Steam Electric Industry Annual 

Discharges to the Chesapeake Bay

• 2.2 million pounds of total nitrogen 

• 21,500 pounds of zinc 

• 5,180 pounds of arsenic 

• 1,820 pounds of cadmium 

• 168 pounds of mercury
Section 3—Environmental And Human Health Concerns

3-20 

sources include agricultural land runoff, atmospheric deposition, forest land runoff, nonregulated 

stormwater runoff, stream banks and tidal shorelines, tidal resuspension, the ocean, wildlife, and 

natural background [U.S. EPA, 2010d].

EPA identified 1,679 NPDES-permitted facilities discharging industrial wastewaters in 

the Chesapeake Bay watershed. In 2009, these facilities contributed an estimated 7.3 million 

pounds of total nitrogen and 1.27 million pounds of total phosphorus to the Bay, an estimated 

3 percent and 8 percent, respectively, of all nitrogen and phosphorus loadings delivered to 

Chesapeake Bay watershed [U.S. EPA, 2010d]. EPA identified 20 steam electric power plants 

discharging to the Chesapeake Bay watershed and estimated that these plants discharge

2.2 million pounds of nitrogen and 60,000 pounds of phosphorus to the Bay annually [ERG, 

2013c]. This suggests that the evaluated waste streams from steam electric power plants 

contribute 30 percent of the total nitrogen loadings and approximately 5 percent of the total 

phosphorus loadings to the Chesapeake Bay from NPDES-permitted sources [ERG, 2013c].

Historically, studies of water quality issues in the Chesapeake Bay have focused on 

nutrients; however, in 1999 EPA assessed the impact of toxic pollutants entering the Bay 

including some metals found in steam electric power plant discharges (e.g., arsenic, cadmium, 

copper, lead, mercury, and zinc). Although EPA concluded that the majority of impacts were 

localized issues, EPA estimated the total metal pollutant loadings from point sources discharging 

to the Bay. Table 3-6 presents the baseline pollutant loadings for the evaluated waste streams and 

the estimated loadings from all point sources to the Chesapeake Bay watershed. The results 

indicate that pollutant loadings from the evaluated waste streams represent a large portion of the 

point source metal loadings to the Chesapeake Bay watershed for arsenic, cadmium, lead, and 

zinc. 

Table 3-6. Comparison of Steam Electric Pollutant Loadings to Other Point Source 

Discharges to the Chesapeake Bay Watershed

Pollutant

Steam Electric Baseline 

Loadings to the Chesapeake 

Bay Watershed (lbs/year) a

Total Point Source Loadings to 

the Chesapeake Bay Watershed

(lbs/year) b,c

Percentage of Point 

Source Loadings from 

Steam Electric Plants

Arsenic 5,180 3,500 (c) 100%

Cadmium 1,820 3,000 (c) 61%

Copper 5,150 78,100 (c) 7%

Lead 5,630 15,000 (c) 38%

Mercury 168 2,660 (c) 6%

Zinc 21,500 125,000 (c) 17%

Total Nitrogen 2,200,000 7,340,000 (b) 30%

Total Phosphorus 60,000 1,270,000 (b) 5%

a –ERG, 2013c. 

b – U.S. EPA, 2010d. 

c – Chesapeake Bay Program, 1999.

The estimated total point source loadings of arsenic from the 1999 Chesapeake Bay Basin 

Toxics Loading and Release Inventory [Chesapeake Bay Program, 1999] was less than the 

estimated amount of arsenic discharged from the 20 steam electric power plants. This 
Section 3—Environmental And Human Health Concerns

3-21 

inconsistency may be due to incomplete data sets. In the report, the Program noted that point 

source loadings are based on best available data and estimated only for major facilities (facilities 

with a flow of 0.5 million gallons per day or greater) included in EPA’s Permit Compliance 

System (PCS). As part of their NPDES permits, many point sources are not required to monitor 

for arsenic and other pollutants associated with the waste streams of concern; therefore, the 

report might not account for these pollutant loadings. In addition, the data are also over 10 years 

old and metal pollutant loadings to the Bay may have changed during that time (i.e., increased 

arsenic discharges).

To provide additional perspective on the magnitude of the loadings, EPA calculated the 

equivalent number of typical POTWs that would discharge loadings equal to the 20 steam 

electric power plants that discharge to the Chesapeake Bay watershed. Table 3-7 presents total 

pollutant loadings for the evaluated waste streams discharging to the Chesapeake Bay and the 

number of typical POTWs that would discharge equivalent loadings. 

Table 3-7. Estimated Number of POTW Equivalents for Pollutant Loadings to the 

Chesapeake Bay Watershed from the Evaluated Waste Streams

Pollutant

Annual Discharge to the Chesapeake 

Bay Watershed, pounds (lbs) a

Equivalent Number of Typical 

POTWs b

Arsenic 5,180 113

Cadmium 1,820 455

Chromium VI 681 38

Copper 5,150 33

Lead 5,630 115

Mercury 168 <1

Nickel 20,700 668

Selenium 10,100 561

Thallium 16,700 1,670

Zinc 21,500 48

Total Nitrogen 2,200,000 18

Total Phosphorus 60,000 3

a – ERG, 2013c. 

b – Equivalent number of POTWs is estimated by dividing the total annual pollutant loadings to the Chesapeake Bay 

by the average POTW loadings presented in Table 3-4 for a 4-MGD POTW.

The results demonstrate that the magnitude of the total loadings from 20 steam electric 

power plants discharging to the Chesapeake Bay is equivalent to: 

• Over 100 typical POTW discharges of arsenic and lead; 

• Over 450 typical POTW discharges of cadmium; 

• Over 550 typical POTW discharges of nickel and selenium; and 

• Over 1,600 typical POTW discharges of thallium. 

This suggests that, for the evaluated waste streams, 20 steam electric plants contribute 

substantial metal loadings to the Chesapeake Bay when compared to typical POTW discharges. 
Section 3—Environmental And Human Health Concerns

3-22 

3.2.5 Pollutant Loadings to the Great Lakes Watershed 

Environmental impacts documented in the Great Lakes are associated with a range of 

stressors, including toxic and nutrient pollutants, invasive species, and habitat degradation. EPA 

and Environment Canada have focused their Great Lakes Binational Toxics Strategy on 

persistent toxic substances such as mercury [U.S. EPA and Environment Canada, 1997]. 

Mercury is a concern in all of the Great Lakes due to its bioaccumulation in fish and wildlife and 

potential impacts on humans. For example, in a study of 65 hair samples from fish-eating and 

non-fish-eating women, average mercury concentrations in hair were significantly greater (i.e., 

128 to 443 percent higher concentration) for women who ate several meals of sport-caught fish

from the Great Lakes. EPA and Environment Canada have documented a range of wildlife 

impacts from mercury in the Great Lakes such as an increase of physiological abnormalities in 

herring gulls [U.S. EPA and Environment Canada, 2009]. 

The primary source of mercury in the Great Lakes watershed is atmospheric deposition 

from sources around the Great Lakes watershed (e.g., fuel combustion, incineration, and 

manufacturing) emitting approximately 70,000 pounds of mercury annually [Evers et. al., 2011]. 

When compared to atmospheric deposition, mercury contributions from point source discharges 

are less of a concern. Due to the bioaccumulative nature of mercury, EPA has placed strict 

controls (e.g., mixing zones are not allowed in permits) to limit the total amount of mercury 

entering the Great Lakes watershed. Monitoring within the Great Lakes watershed has indicated 

a decrease in mercury point source discharges, 

primarily because of implemented control strategies. 

EPA identified 26 steam electric power plants 

discharging to the Great Lakes watershed with the 

majority discharging to Lake Michigan (14 plants) 

and Lake Erie (4 plants) [ERG, 2013c]. In the Lake 

Erie Management Plan, EPA identified steam 

electric discharges as contributing 57 percent of the 

mercury to the Lake Erie from wastewater sources 

[U.S. EPA, 2008b]. 

Table 3-8 presents the loadings from steam electric power plants discharging to the Great 

Lakes watershed. EPA did not identify any documented analysis of total point source discharges 

to the Great Lakes to use as a comparison to the steam electric loadings. EPA did identify data 

on nutrient loadings to the Great Lakes watershed; the comparison of steam electric loadings to 

total nutrient discharges is presented after Table 3-8. When evaluating impacts from 

bioaccumulative pollutants, the potential for pollutant retention in still or slow-moving water, 

such as the Great Lakes, is a particular concern. Many pollutants in combustion wastewater can 

bioaccumulate in fish and then affect higher trophic levels and terrestrial environments. 

Steam Electric Industry Annual 

Discharges to the Great Lakes

• 2 million pounds of total nitrogen 

• 19,800 pounds of zinc 

• 6,240 pounds of selenium 

• 4,170 pounds of arsenic 

• 1,410 pounds of cadmium 

• 117 pounds of mercury
Section 3—Environmental And Human Health Concerns

3-23 

Table 3-8. Steam Electric Pollutant Loadings to the Great Lakes Watershed

Pollutant

Steam Electric Baseline Loadings to the Great Lakes

Watershed (lbs/year)

Arsenic 4,170

Cadmium 1,410

Chromium VI 380

Copper 5,180

Lead 5,840

Mercury 117

Nickel 18,300

Selenium 6,240

Thallium 15,900

Zinc 19,800

Total Nitrogen 1,990,000

Total Phosphorus 53,200

Source: ERG, 2013c. 

Nutrients in the Great Lakes also cause ecological issues (i.e., eutrophication). Due to this 

concern, Robertson and Saad [2011] used the SPARROW (SPAtially Referenced Regressions 

On Watershed attributes) model to calculate discharges of nitrogen and phosphorus loadings to 

the Great Lakes using long-term mean annual loadings (normalized to base year 2002). The 

nitrogen and phosphorus loadings from all sources in the United States (including non-point 

sources) to the Great Lakes were 608 million and 

25 million pounds, respectively. Depending on the 

specific lake, point sources contributed between 14 

and 44 percent of total phosphorus loadings and 

between 13 and 34 percent of total nitrogen 

loadings in the Great Lakes [Robertson and Saad, 

2011]. 

The total phosphorus loadings from U.S. 

point sources to the Great Lakes watershed is 4.8 

million pounds; the steam electric industry 

contributes approximately 1 percent of the point 

source discharges for phosphorus. EPA estimated 

the total nitrogen loadings from point sources to be 

between 79 and 207 million pounds per year9

[Robertson and Saad, 2011]; the steam electric 

industry contributes between 2.5 and less than one 

percent of the point source loadings for nitrogen. 

To provide additional perspective on the magnitude of the loadings, EPA calculated the 

equivalent number of typical POTWs that would discharge a loadings equal to the 26 steam 

electric power plants that discharge to the Great Lakes. Table 3-9 presents total pollutant 

 

9 Depending on the lake, point sources represent between 13 to 34 percent of the total nitrogen loading to the Great 

Lakes (values not provided in reference by lake name).

Industry Loadings to the Great Lakes 

Compared to POTWs

26 steam electric power plants discharge 

to the Great Lakes. Loadings from these 

plants are equivalent to:

• Over 1,500 typical POTW discharges 

of thallium;

• Over 550 typical POTW discharges 

of nickel; 

• Over 350 typical POTW discharges 

of cadmium; 

• Over 300 typical POTW discharges 

of selenium; 

• Over 100 typical POTW discharges 

of lead. 
Section 3—Environmental And Human Health Concerns

3-24 

loadings for the evaluated waste streams discharging to the Great Lakes and the number of 

typical POTWs that would discharge equivalent loadings. 

Table 3-9. Estimated Number of POTW Equivalents for Pollutant Loadings to the Great 

Lakes from the Evaluated Waste Streams

Pollutant

Annual Discharge to the Great 

Lakes, pounds (lbs) a

Equivalent Number of Average 

POTWs b

Arsenic 4,170 91

Cadmium 1,410 352

Chromium VI 380 21

Copper 5,180 34

Lead 5,840 119

Mercury 117 <1

Nickel 18,300 591

Selenium 6,240 347

Thallium 15,900 1,590

Zinc 19,800 44

Total Nitrogen 1,990,000 16

Total Phosphorus 53,200 3

a – ERG, 2013c. 

b – Equivalent number of POTWs is estimated by dividing the annual pollutant loadings to Great Lakes by the 

average POTW loadings presented in Table 3-4 for a 4-MGD POTW.

The results demonstrate that the magnitude of the total loadings from 26 steam electric 

power plants discharging to the Great Lakes is equivalent to a significantly larger number of 

typical POTWs for many of the pollutants commonly known to cause environmental harm. 

These 26 plants discharge a loadings equivalent to: 

• Over 1,500 typical POTW discharges of thallium; 

• Over 550 typical POTW discharges of nickel; 

• Approximately 350 typical POTW discharges of cadmium and selenium; 

• Over 100 typical POTW discharges of lead. 

This suggests that, for the evaluated waste streams, 26 steam electric plants contribute 

substantial metal loadings to the Great Lakes when compared to typical POTW discharges. 

3.3 LONG ENVIRONMENTAL RECOVERY TIMES ASSOCIATED WITH POLLUTANTS IN STEAM 

ELECTRIC WASTE STREAMS 

Recovery of the environment from exposure to combustion wastewater is affected by

continued cycling of contaminants within the ecosystem, bioaccumulation, and the potential 

alterations to ecological processes, such as population and community dynamics in the 

surrounding ecosystems. The ability of aquatic and adjacent terrestrial environments to recover 

from even short periods of exposure to combustion wastewater depends on the distance from 

discharge, the pollutant concentrations, pollutant residence time, and the time elapsed since 

exposure. In particular, accumulation of metals in sediments can slow recovery of aquatic 
Section 3—Environmental And Human Health Concerns

3-25 

systems following exposure to combustion wastewater 

due to the potential for resuspension in the water column 

and for benthic organisms to provide a pathway for 

exposure long after combustion wastewater discharges 

have ended. For example, Lemly [1985, 1997, 1999] 

documented that benthic pathways can continue to 

provide toxic doses of selenium to wildlife even 10 years

after water column selenium concentrations are below 

levels of concern. Ruhl [2012] documented elevated 

levels of combustion wastewater pollutants (including arsenic and selenium) in pore water, even 

in cases where the water column concentrations are not elevated. This study found that arsenic is 

retained in lake sediments and pore water through a cycle of adsorption and desorption, likely in 

response to seasonal changes in the lake water chemistry [Ruhl, 2012]. 

As discussed in Section 3.1, many of the pollutants in combustion wastewater (e.g., 

arsenic, mercury, selenium) readily bioaccumulate in exposed biota. The bioaccumulation of 

these pollutants is of particular concern due to their potential for impacting higher trophic levels, 

local terrestrial environments, and transient species, in addition to the aquatic organisms directly 

exposed to the wastewater. Aquatic systems with long residence times and potential

contamination with bioaccumulative pollutants often experience persistent environmental effects 

following exposure to combustion wastewater. 

Population decline attributed to exposure to combustion wastewater can alter the 

structure of aquatic communities and cause cascading effects within the food web that result in 

long-term impacts to ecosystem dynamics [Rowe et al., 2002]. Reductions in organism survival 

rates from abnormalities caused by exposure to combustion wastewater and alterations in 

interspecies relationships, such as declines in the abundance or quality of prey, can delay

ecosystem recovery until key organisms within the food web return to levels prior to combustion 

wastewater exposure. In a 1980 study of Rocky Run Creek by Forbes and Magnuson, fungal 

decomposition of detritus was limited due to the effects of combustion wastewater. As a result, 

the benthic invertebrate population, which graze on detrital material, declined as did benthic fish 

that prey upon small invertebrates due to a 

reduction in available resources [Forbes and 

Magnuson, 1980]. 

Belews Lake, a 1,500-hectare cooling 

reservoir constructed to support the Belews 

Creek Steam Station in Stokes County, North 

Carolina, is a well-documented case study that 

highlights the effects combustion wastewater

can have on fish populations and the 

subsequent long recovery time. In 1970, Duke 

Power began monitoring the fish populations 

in Belews Lake prior to any discharges of 

combustion wastewater. From 1974 to 1985, 

Duke Energy discharged ash pond effluent into 

Belews Lake. Almost immediately after these 

Short Exposures to Combustion 

Wastewater Can Equate to 

Lasting Ecological Effects 

In Martin Lake, ecological effects 

persisted for at least eight years 

following eight months of fly ash 

discharges into the lake. 

Studies have linked historical discharges of selenium 

from the Belews Creek Steam Station with persistent 

ecological impacts in the plant’s cooling reservoir.
Section 3—Environmental And Human Health Concerns

3-26 

discharges began, rapid and dramatic changes in the fish populations were observed [Lemly, 

1993]. By 1975, morphological abnormalities (e.g., partial fin loss, head deformities, cataracts) 

were reported for all 19 fish species monitored in the lake. Within two years following the 

release of ash pond effluent into the lake, several species experienced complete reproductive 

failure with only four species remaining by 1978 (i.e., four years after discharges began). Water 

samples collected in the lake reported elevated levels of arsenic, selenium, and zinc. Large 

predatory fish were some of the first species to die out completely, due to the lethal and sublethal 

effects of exposure to ash pond effluent. Because a top predator was gone, some fish that 

exhibited developmental abnormalities were able to survive, despite their otherwise high 

susceptibility to predation [Lemly, 1993]. The study eventually correlated the observed fish 

abnormalities with high selenium whole-body concentrations, and identified the planktonic 

community as the key source of selenium to the impacted fish. In 1985, the Belews Creek Steam 

Station switched to disposing of the coal ash in a dry landfill and ended the ash pond discharges 

to the lake. In a 1997 study, Lemly determined that there was evidence that the lake was 

recovering; however, even 11 years after the discharges ceased, selenium levels in the sediments 

still posed a risk to wildlife that feed on benthic organisms. Lemly also observed that despite the 

reduction in the selenium concentration in fish ovaries, reproductive abnormalities remained 

persistent, highlighting the long ecological recovery time observed in the Belews Lake. 

In addition to population density effects, communities in both field and experimental 

studies exposed to combustion wastewater have also experienced alterations in species diversity, 

which can further prolong ecosystem recovery [Benson and Birge, 1985; Guthrie and Cherry, 

1976; Rowe et al., 2001; Specht et al., 1984]. In a study of fish populations in Martin Lake 

following a short eight-month period in which the lake received fly ash pond discharges, both 

planktivorous (i.e., diet primarily consists of plankton) and carnivorous (i.e., diet primarily 

consists of meat) fish populations were severely reduced [Garrett and Inman, 1984]. Three years 

after the effluent release was halted, planktivorous fish populations remained extremely low, 

while carnivorous fish populations had nearly recovered. Carnivorous fish have a more diverse 

diet than planktivorous fish and therefore benefited from an increase in food availability as the 

aquatic system recovered; however, the size of carnivorous fish present in the lake suggested that 

surviving adults continued to have reproductive impairments [Garrett and Inman, 1984]. 

Sorensen (1988) documented that ecological impacts in the lake remained evident even up to 

eight years after the eight-month exposure to fly ash discharges, with sunfish populations 

continuing to exhibit tissue damage to the liver, kidneys, gills, and ovaries and impaired overall 

reproductive health. 

3.4 DISCHARGE TO SENSITIVE ENVIRONMENTS

The pollutant loadings and long ecological recovery times discussed in Section 3.3 are 

also of concern due the proximity of many steam electric power plants to sensitive environments 

where the characteristics of combustion wastewater may impair water quality (e.g., 303(d)-listed 

waters and waters with fish advisories) or pose a threat to threatened and endangered species. 
Section 3—Environmental And Human Health Concerns

3-27 

EPA identified the number of surface waters that receive discharges of the evaluated waste 

streams and are located in close proximity to the following sensitive environments:10

• Impaired waters;

• Fish consumption advisory waters; and

• Threatened and endangered species habitats. 

Table 3-10 summarizes the number and percentage of immediate receiving waters 

identified in each sensitive environment category. 

Table 3-10. Number and Percentage of Immediate 

Receiving Waters Identified as a Sensitive Environment

Sensitive Environment

Number (Percentage) of Immediate 

Receiving Waters Identified a

Impaired water 162 (51%)

Surface water impaired for a subset of pollutants associated 

with the evaluated waste streams b 80 (25%) 

Fish consumption advisory water 189 (60%)

Surface water with a fish consumption advisory for a subset of 

pollutants associated with the evaluated waste streams c 119 (38%) 

a – For the sensitive environment proximity analysis, EPA evaluated 317 immediate receiving water

combinations that receive discharges of the evaluated waste streams [ERG, 2013e; ERG, 2013l]. 

b – Table B-1 in Appendix B contains a complete list of the impairment categories identified in EPA’s 303(d)-

listed waters and designates the subset of pollutants evaluated.

c – Table B-2 in Appendix B contains a complete list of the types of advisories identified under the sensitive 

environment proximity analysis, including pollutants that are not associated with the evaluated waste streams.

3.4.1 Proximity to Impaired Waters 

A surface water is classified as a 303(d) impaired water when pollutant concentrations 

exceed water quality standards and the surface water can no longer meet its designated uses (e.g., 

drinking, recreation, and aquatic habitat). Based on that definition, half of the immediate 

receiving waters included in the EA are impaired waters.11 EPA reviewed the identified 303(d) 

impairment categories and determined approximately 25 percent of the immediate receiving 

waters are impaired for a pollutant associated with the evaluated waste streams. Table 3-11

presents the number and percentage of immediate receiving waters that are impaired for a 

pollutant associated with the evaluated waste streams. Figure 3-1, Figure 3-2, and Figure 3-3

illustrate the geographical location of plants that directly discharge combustion wastewater to a 

water classified as impaired by high concentrations of arsenic, mercury, selenium, metals (other 

than mercury), and nutrients. 

 

10 ERG memorandum Proximity Analysis Methodology (DCNS SE02151), describes the methodology used to 

evaluate the proximity of steam electric power plants to sensitive environments.

11 Table B-1 in Appendix B contains a complete list of the impairment categories identified under the sensitive 

environments proximity analysis, including pollutants that are not associated with the evaluated waste streams. 
Section 3—Environmental And Human Health Concerns

3-28 

Table 3-11. Number and Percentage of Immediate Receiving Waters Classified as 

Impaired for a Pollutant Associated with the Evaluated Waste Streams 

Pollutant Causing Impairment

Number (Percentage) of Immediate 

Receiving Waters Identified a

Arsenic 3 (1%)

Cadmium 5 (2%)

Chlorides 3 (1%)

Chromium b 4 (1%)

Copper 7 (2%)

Lead 7 (2%)

Manganese 5 (2%)

Mercury 52 (16%)

Nutrients 30 (9%)

Phosphorus 16 (5%)

Selenium 3 (1%)

TDS 4 (1%)

Zinc 4 (1%)

a – For the impaired waters proximity analysis, EPA evaluated 317 immediate receiving water combinations that 

receive discharges of the evaluated waste streams [ERG, 2013e; ERG 2013l]. 

b – Impairment category is for total chromium. An impairment type is not designated specifically for chromium VI.

Figure 3-1. Location of Plants that Directly Discharge Combustion Wastewater 

to a Surface Water Impaired due to Arsenic, Mercury, and Selenium
Section 3—Environmental And Human Health Concerns

3-29 

Figure 3-2. Location of Plants that Directly Discharge Combustion Wastewater 

to a Surface Water Impaired due to Metals Other than Mercury

Figure 3-3. Location of Plants that Directly Discharge Combustion 

Wastewater to a Surface Water Impaired due to Nutrients
Section 3—Environmental And Human Health Concerns

3-30 

3.4.2 Proximity to Fish Consumption Advisory Waters 

Fish consumption advisories are issued by states, territories, and authorized tribes when 

pollutant concentrations in fish tissue are considered unsafe for consumption [U.S. EPA, 2011e]. 

EPA determined that 60 percent of the immediate receiving waters included in the EA are under 

fish consumption advisories; however, only 38 percent of the immediate receiving waters are 

under an advisory for a pollutant associated with the evaluated waste streams.12 Table 3-12

identifies the number of immediate receiving waters with a fish consumption advisory for a 

pollutant associated with an evaluated waste stream. Figure 3-4 illustrates the geographical 

location of plants that directly discharge combustion wastewater to surface waters with a fish 

consumption advisory for cadmium, lead, and mercury. 

Table 3-12. Number and Percentage of Immediate Receiving Waters Issued a Fish 

Consumption Advisory for a Pollutant Associated with the Evaluated Waste Streams

Advisory Type a

Number (Percentage) of PlantReceiving Waters Identified b

Cadmium 1 (<1%)

Lead 3 (1%)

Mercury 118 (37%)

a – EPA did not identify any immediate receiving waters that were issued fish consumption advisories for arsenic 

or selenium.

b – For the sensitive environment proximity analysis, EPA evaluated 317 immediate receiving water combinations 

that receive discharges of the evaluated waste streams [ERG, 2013e; ERG, 2013l]. 

 

12 Table B-2 in Appendix B contains a complete list of the types of advisories identified under the sensitive 

environment proximity analysis, including pollutants that are not associated with the evaluated waste streams.
Section 3—Environmental And Human Health Concerns

3-31 

Figure 3-4. Location of Plants that Directly Discharge to a Surface Water with a Fish 

Consumption Advisory for Cadmium, Lead, and Mercury 

3.4.3 Proximity to Threatened and Endangered Species Habitats

Under the Endangered Species Act (ESA), endangered species are those in danger of 

extinction throughout all or a significant portion of its range. Threatened species are those 

species that are likely to become endangered within the foreseeable future. A species may be 

listed solely on the basis of their biological status and threats to their existence. The U.S. Fish 

and Wildlife Service (FWS) considers five factors for listing: 1) damage to, or destruction of, a 

species’ habitat; 2) overutilization of the species for commercial, recreational, scientific, or 

education purposes; 3) disease or predation; 4) inadequacy of existing protection; and 5) other 

natural or manmade factors that affect the continued existence of the species. 

EPA evaluated the extent to which the estimated range and critical habitats of currently 

listed threatened and endangered species, or those in consideration for listing under the ESA (as 

of January 23, 2012) overlaps with surface waters that receive discharges of the evaluated waste 

streams. EPA identified surface waters estimated to exceed NRWQC for the protection of 

aquatic life under baseline conditions (see Section 5.3) as “affected areas” with the potential to 

harm threatened and endangered species. EPA determined that 224 threatened and endangered 

species habitats are located within an “affected” surface water under baseline conditions. 

In addition, EPA assessed the vulnerability of each species identified to changes in water 

quality and developed the following categories: 

• High vulnerability – species living in aquatic habitats for several life history stages 

and/or species that obtain a majority of their food from aquatic sources.
Section 3—Environmental And Human Health Concerns

3-32 

• Moderate vulnerability – species living in aquatic habitats for one life history stage 

and/or species that obtain some of their food from aquatic sources. 

• Low vulnerability – species whose habitats overlap bodies of water, but whose life 

history traits and food sources are terrestrial.

EPA classified 52 percent of the species (127 of 224 species) with habitats located within 

an “affected” surface water as highly vulnerable to changes in water quality. For further details 

on the threatened and endangered species analysis and results see the Benefits and Cost Analysis 

for the Proposed Effluent Limitations Guidelines and Standards for the Steam Electric Power 

Generating Point Source Category (DCN SE03172) (Benefits and Cost Analysis).

3.4.4 Proximity to Drinking Water Resources

EPA also evaluated the potential for steam electric power plants to pose a threat to public 

sources of drinking water. Although many of the pollutants (e.g., selenium, mercury, arsenic, 

nitrates) in the evaluated waste streams would likely be reduced to safe levels during drinking 

water treatment, these pollutants could potentially impact the effectiveness of the treatment 

processes, which could increase public drinking water treatment costs.13 EPA evaluated the 

proximity of steam electric power plants to the following sensitive environments for drinking 

water resources: 

• Drinking water intakes – drinking water sources that collect surface water through a 

public water system. Intakes are protected under the Safe Water Drinking Act 

(SDWA) of 1974 and its 1986 and 1996 amendments, which require delegated states 

and tribes to perform routine testing to ensure that they meet state drinking water 

standards. 

• Public wells – drinking water sources that collect ground water through a public 

water system. Public wells are protected under the SDWA, which requires delegated 

states and tribes to perform routine testing to ensure that they meet state drinking 

water standards. 

• Sole-source aquifers – drinking water sources that supply at least 50 percent of the 

drinking water consumed in the area overlying the aquifer. These areas can have no 

reasonably available alternative drinking water source(s) if the aquifer were to 

become contaminated. 

• Table 3-13 summarizes the number and percentages of plants included in the 

national-scale proximity analysis that are located within 5 miles of the evaluated 

drinking water resources. 

 

13 For more information on drinking water treatment processes used to reduce or eliminate metals commonly 

detected in the evaluated waste streams from steam electric power plants, see the ERG memorandum Drinking 

Water Treatment Technologies that Can Reduce Metal and Selenium Concentrations Associated with Discharges 

from Steam Electric Power Plants (DCN SE02154).
Section 3—Environmental And Human Health Concerns

3-33 

Table 3-13. Comparison of Number and Percentage of Steam Electric Power Plants 

Located within 5 Miles of a Drinking Water Resource

Drinking Water Resource

Number (Percentage) of Plants

Located within 5 Miles of a

Drinking Water Resource a

Intake 116 (37%)

Public well 268 (85%)

Sole-source aquifer 15 (5%)

a – For the drinking water resource proximity analysis, EPA evaluated 317 immediate receiving water combinations 

that receive discharges of the evaluated waste streams [ERG, 2013e; ERG, 2013l]. 

3.5 DOCUMENTED ENVIRONMENTAL IMPACTS

The documented environmental impacts from exposure to combustion wastewater 

indicate that the threat these wastes pose to human health and wildlife is a widespread problem 

that is not isolated to a few unique locations or circumstances. EPA identified over 130 steam 

electric power plants14 causing environmental impacts to surface water and ground water 

environments following exposure to combustion wastewater, which are summarized in Table A3. Impacts identified in the literature include lethal and sublethal impacts on fish, impacts on the 

diversity and size of populations in the ecosystem, and impacts on drinking water quality. 

Although EPA did not find evidence of human health impacts, documented impacts of MCL 

exceedances downstream of steam electric power plants and the issuance of fish advisories in 

waters that receive combustion wastewater indicate that there is a potential for human health 

impact. This section summarizes the documented surface water and ground water case studies 

and damage cases and discusses the potential for similar impacts to occur at other steam electric 

power plants. 

 

14 For several damage cases, the specific plant associated with the site was not identified. EPA used information 

available in the literature and proximity of the plant to the damage case site to identify the plant. See footnotes i and 

j in Table A-3 for further details on EPA’s assumptions. 
Section 3—Environmental And Human Health Concerns

3-34 

3.5.1 Case Studies and Damage Cases Documenting Surface Water Impacts

EPA identified 132 case studies and damage cases 15 from 55 steam electric power 

plants16 that document surface water impacts following exposure to combustion wastewater 

[AECOM, 2009; ASU, 2009; DRBC, 2006; EIP et al., 2010a and 2010b; ERG, 2012b; Gazette, 

2011; MDNRE, 2010; Ruhl, 2012; U.S. EPA, 2007b; U.S. EPA, 2010e]. Surface water impacts 

include damage to fish populations (i.e., physiological and morphological abnormalities and 

various behavioral, reproductive, and developmental effects), decreased diversity in insect 

populations, and decline of aquatic macroinvertebrate population. Table 3-14 highlights several 

case study sites identified in the peer-reviewed 

literature where negative surface water impacts 

from steam electric discharges have been 

studied. In most cases, negative impacts have 

been studied and documented in multiple 

articles and reports. The table also lists the 

number of literature documents that discussed 

impacts at each site and summarizes these 

impacts. In addition to the literature case 

studies, EPA also identified damage cases in a 

separate review [U.S. EPA, 2012b; U.S. EPA, 

2013e]. These are summarized in Appendix A 

in Tables A-6 and A-7, which summarize the 

damage cases from combustion residuals 

surface impoundments and landfills, 

respectively.

 

15 EPA defines “case study” and “damage case” as documented impacts to ground water and/or surface water from 

combustion wastewater. A given steam electric power plant may be associated with multiple case studies and 

damage cases.

16 For several damage cases, the specific plant associated with the site was not identified. EPA used information 

available in the literature and proximity of the plant to the damage case site to identify the plant. See footnotes j and 

k in Table A-3 for further details on EPA’s assumptions.

Some wastewater surface impoundments are located in, 

or near, large river floodplains. Failure of the 

embankments of surface impoundments can release 

catastrophic amounts of pollutants into surrounding 

ecosystems.
3-35

Section 3—Environmental And Human Health Concerns

Table 3-14. Summary of Select Documented Surface Water Impact Case Studies

Site Name and 

Location

Number of Documents 

that Discuss Surface 

Water Impacts at the Site Case Study Overview

Savannah River 

Site, SC

23 The Savannah River Site, which is owned by the Department of Energy (DOE), is divided into several areas, 

based on production, land use, and other related characteristics. The D-area, a site utilized by numerous 

ecologists to study the impacts of coal-fired power plant waste, houses a coal-fired power plant that discharges 

ash into a series of ponds and a swamp that ultimately drains into the Savannah River. Numerous studies 

observed organisms within these habitats accumulated high concentrations of trace elements in their tissues 

and exhibited various physiological, behavioral, and developmental effects.

Belews Lake, NC 13 In 1970, Duke Power Company constructed Belews Lake as a cooling water reservoir to support the Belews 

Creek Steam Station. Almost immediately after ash pond effluent began discharging into the lake, fish 

populations experienced morphological changes, reproductive failure, and eventually death. In 1985, Belews 

Creek Steam Station converted to a dry-ash transport system, ending the ash pond discharges to the lake. 

However, even 11 years after the discharges ceased, reproductive abnormalities persisted in the fish 

populations. 

Martin Lake, TX 8 Martin Lake is a cooling water reservoir that also receives combustion wastewater discharges. In 1978 and 

1979, a series of major fish kills occurred due to the elevated concentrations of selenium in the water and fish 

tissue. Numerous studies conducted throughout the 1980s documented histopathological and reproductive 

damage in the fish populations inhabiting the lake. In addition, the studies determined that the overall health of 

the aquatic populations near the discharge site remained adversely affected by the selenium pollution, despite 

the reduction in the annual discharge of selenium. In 1992, a fish consumption advisory was issued for the 

lake due to discharges from the steam electric plant. 

Hyco Reservoir, 

NC

8 Hyco Reservoir is a large cooling water reservoir that received effluent from a power plant’s fly ash ponds. In 

1981, a large-scale fish kill occurred in the reservoir, prompting numerous scientific studies to examine the 

extent and cause of the environmental damage. Multiple studies detected selenium concentrations in the water 

and tissue of fish inhabiting the reservoir, while other trace elements were within normal concentration ranges. 

The results of these studies indicate that the selenium concentrations induced lethal effects in the fish 

populations. 

Glen Lyn, VA 5 Glen Lyn Plant discharged fly ash sluice water from an ash pond into Adair Run, a tributary of the New River. 

A 1984 study reported that the local insect diversity and density remained essentially the same upstream 

(reference site) and downstream of the ash pond when the pond was not close to capacity. However, as the 

settling pond reached its capacity, the insect density and diversity declined downstream. After closure of the 

pond, it took up to 10 months for the insect populations to recover [Specht et al., 1984].
3-36

Section 3—Environmental And Human Health Concerns

Table 3-14. Summary of Select Documented Surface Water Impact Case Studies

Site Name and 

Location

Number of Documents 

that Discuss Surface 

Water Impacts at the Site Case Study Overview

Gibson Lake, IN 4 Gibson Lake is a man-made, shallow impoundment that receives ash pond effluent from Gibson Generating 

Station. Starting in 1986, least terns, an endangered species of migratory birds, began using the dike in Gibson 

Lake as a nesting ground for breeding. To protect the birds from potential toxic exposure, the plant began a 

cooperative program with the Indiana Department of Natural Resources to protect the nesting birds by creating 

a nearby alternative habitat, known as Cane Ridge Wildlife Management Area (WMA), which received water 

pumped from Gibson Lake. In April 2007, Duke Energy closed access to the lake for recreational fishing due 

to elevated selenium levels. A year later, the U.S. Fish and Wildlife Service (USFWS) became concerned 

about selenium levels in the water and fish in the Cane Ridge WMA. The USFWS stopped the flow of water 

from Gibson Lake into Cane Ridge, discouraged least terns from using the refuge, removed the contaminated 

fish, and plowed Cane Ridge to redistribute and bury the selenium in the soil. Subsequently, the USFWS 

stopped the flow of water from Gibson Lake into Cane Ridge and piped water from Wabash River instead. 

Cane Ridge was restocked with fish to lure back migratory birds. As of June 2009, avocets, dunlins, black 

terns, Forster's terns, Caspian terns, and 50 endangered least terns have returned to Cane Ridge.

Rocky Run 

Creek, WI

5 Rocky Run Creek receives effluent from Columbia Generating Station’s ash pond. After the generating station 

began operation in 1975, the aquatic macroinvertebrate populations declined in the area. Two studies 

conducted at this site concluded that population density decreased, not because of death due to coal ash 

toxicity, but because the aquatic macroinvertebrate populations avoided the area due to sublethal alterations in 

the creek. 

McCoy Branch, 

TN

3 In 1986, coal ash slurry discharges from DOE’s Chestnut Ridge Y-12 power plant into McCoy Branch were 

found to contain elevated concentrations of trace elements, which violated the Tennessee Water Quality Act. 

A 1992 report conducted by DOE documented bioaccumulation of contaminants in fish tissues, decreased 

diversity in benthic macroinvertebrate communities, and increased fish mortality and abnormalities at the site 

[DOE, 1992]. 

Welsh Reservoir, 

TX

2 Welsh Reservoir serves as a cooling water reservoir for Welsh Power Plant. From 1986 to 1989, the Texas 

Park and Wildlife Department (TPWD) reported increases in the selenium concentrations of the fish inhabiting 

the receiving water. As a result, the Texas Department of Health (TDH) issued a fish consumption advisory 

for the reservoir because of the potential health impact due to the levels of selenium in fish. In 1998, TDH 

collected 20 fish for reevaluation and observed an average selenium concentration in the fish above the 

reported national averages. Therefore, the Agency for Toxic Substances and Disease Registry (ATSDR) 

concluded in a report that there was no clear indication of an overall change in selenium fish tissue 

concentrations over the 12 years [ATSDR, 1998b]. 
3-37

Section 3—Environmental And Human Health Concerns

Table 3-14. Summary of Select Documented Surface Water Impact Case Studies

Site Name and 

Location

Number of Documents 

that Discuss Surface 

Water Impacts at the Site Case Study Overview

Brandy Branch 

Reservoir, TX

1 Brandy Branch Reservoir serves as a cooling water reservoir for Pirkey Power Plant. From 1986 to 1989, the 

TPWD reported increases in the selenium concentrations of the fish inhabiting the receiving water. As a result, 

the Texas Department of Health (TDH) issued a fish consumption advisory for the reservoir, because of the 

potential health impact due to the levels of selenium in fish. Since the fish kills in the 1980s, Southwestern 

Electric Power Company has worked cooperatively to monitor fish tissue selenium concentrations, which have 

decreased since the late 1980s [ATSDR, 1998a]. 

Mountain Island 

Lake, NC

5 Duke Energy's Riverbend Plant discharges ash pond effluent into Mountain Island Lake, which supplies 

drinking water to 700,000 people. The county staff has detected arsenic and zinc concentrations above state 

standards in an area near the ash pond discharge pipe (Charlotte Observer, 2010). The plant continues to 

extensively monitor metal concentrations in Mountain Island Lake surrounding the point of discharge 

[NCDENR, 2011]. 

TVA’s Kingston 

Fossil Plant, TN

6 On December 22, 2008, the retaining wall of a coal ash pond at TVA’s Kingston Fossil Plant broke and 

released billions of gallons of coal ash slurry into the Emory, Clinch, and Tennessee Rivers. The only 

published studies conducted at this site are of initial assessments of the potential impacts to the aquatic life and 

human health. The primary concern addressed in the available literature is the high concentration of mercury 

detected in the river sediments, which may pose a long-term threat to the ecology of these rivers.

Source: ERG, 2013b.
Section 3 - Environmental And Human Health Concerns

3-38 

3.5.2 Case Studies and Damage Cases Documenting Ground Water Impacts 

Pollutants in combustion residuals can leach into ground water from surface 

impoundments and landfills at the site. Older surface impoundments and landfills are of 

particular concern because they were often built without liners and leachate collection systems. 

Liners are typically made of synthetic material, asphalt, clay, or a composite of materials (e.g., 

synthetic and clay) and are designed to collect leachate and prevent ground water contamination. 

Combustion residuals held in unlined surface impoundments can enter the subsurface and 

contaminate ground water. Unlined landfills, used for the dry disposal of combustion residuals, 

are also subject to leaching as precipitation flows through the residuals pile and dissolves 

pollutants into the leachate, which can eventually migrate into ground water. New facilities are 

increasingly installing liners in surface impoundments and landfills; but pollutants can also enter 

the ground water when liners fail or when a disposal site is situated such that natural ground 

water fluctuations come into contact with the disposed waste. Furthermore, state regulation on 

leachate collection systems and impermeable liners is not uniform [EPRI, 1997; 65 FR 32214–

32237, 2000]. 

EPA identified 123 case studies and damage cases17 from 118 steam electric power 

plants18 that document impacts to ground water quality caused by leachate from combustion 

residuals surface impoundments and landfills [AECOM, 2009; ASU, 2009; DRBC, 2006; EIP et 

al., 2010a and 2010b; ERG, 2012b; Gazette, 2011; MDNRE, 2010; MACo, 2007; U.S. EPA, 

2007b; U.S. EPA, 2010e].19 The majority of the case studies and damage cases reported ground 

water pollutant levels in on-site wells above regulatory levels; however, only a portion of the 

cases indicated off-site contamination. Documented impacts to off-site ground water resources 

may be lower due to long migration times within the subsurface until the leachate reaches a 

known monitoring point [NRC, 2006]. Further, the limited number of case studies documenting 

off-site contamination might reflect the less extensive monitoring of off-site ground water wells 

for evidence of impacts from leachate, which suggests off-site impacts may be underrepresented 

in the documented ground water impacts [Cherry, 2000]. 

In surface impoundments, combustion residuals are in constant contact with water, 

allowing toxic metals to leach into and eventually contaminate ground water. From an 

environmental impacts perspective, combustion residuals surface impoundments are generally 

considered less desirable than landfills for disposal because they provide constant saturated or 

nearly saturated conditions and a relatively large hydraulic driving force to move leachate into 

the subsurface [Theis and Gardner, 1990]. The primary impacts observed from surface 

impoundments include MCL exceedances of arsenic, selenium, cadmium, lead, boron, and 

 

17 EPA defines “case study” and “damage case” as documented impacts to ground water and/or surface water from 

combustion wastewater. A given steam electric power plant may be associated with multiple case studies and 

damage cases.

18 For several damage cases, the specific plant associated with the site was not identified. EPA used information 

available in the literature and proximity of the plant to the damage case site to identify the plant. See footnotes j and 

k in Table A-3 for further details on EPA’s assumptions.

19 In December 2011, EIP released a report titled Risky Business: Coal Ash Threatens America’s Groundwater 

Resources at 19 More Sites (DCN SE1985) identifying 19 additional ground water damage cases. These alleged 

damage cases have not been reviewed or confirmed by EPA. 
Section 3 - Environmental And Human Health Concerns

3-39 

manganese in off-site ground water and drinking water wells. Table A-4 in Appendix A 

summarizes documented ground water damage cases from combustion residuals surface 

impoundments [EIP et al., 2010a and 2010b; U.S. EPA, 2007b]. 

Although more desirable than surface impoundments, landfills pose their own ground 

water contamination risks. If the landfills are not properly lined, the pollutants in combustion 

residuals can leach into the soil during precipitation. In areas with acid rain, the precipitation’s 

low pH can accelerate the leaching of contaminants into ground water. In addition, heavy 

precipitation can not only accelerate leaching, but also carry pollutants in stormwater runoff, 

potentially contaminating ground water or surface water resources [Andersen and Madsen, 

1983]. The primary impacts observed from landfills include MCL exceedances of arsenic, 

selenium, boron, manganese, and sulfates in off-site ground water and drinking water wells 

Table A-5 in Appendix A summarizes documented ground water damage cases from combustion 

residuals landfills [EIP et al., 2010a and 2010b; MDNRE, 2010; U.S. EPA, 2007b]. 

A concern associated with ground water contamination from combustion residuals 

surface impoundments and landfills is the potential for leachate to impact private drinking water 

resources. Numerous damage cases documented pollutant levels exceeding MCLs; however, 

many times the damage case documentation did not specify if the well with the MCL exceedance 

was a monitoring well or a drinking water well. However, the fact that many sites reported MCL 

exceedances in ground water testing suggests that potential impacts to drinking water resources 

are a realistic concern. The following three damage cases are documented instances where 

leachate contamination impacted private drinking water wells. 

Constellation Ash Disposal at Waugh Chapel and Turner Pits – Anne Arundel County, 

Maryland 

For over a decade, Constellation Energy Group (Constellation) supplied fly ash for 

structural fill at the B.B.S.S. Inc. (BBSS) sand and gravel mines in Anne Arundel County, 

Maryland. Fly ash from Constellation’s Brandon Shores and Wagner plants was used to reclaim 

portions of BBSS’s Turner Pit starting in 1995 and the Waugh Chapel Pit starting in 2000. In the 

fall of 2006, Anne Arundel County Health Department officials documented concentrations of 

sulfate and metals (i.e., antimony, beryllium, cadmium, manganese, and nickel) exceeding the 

state’s screening criteria for potable aquifers in residential wells located downgradient from 

Waugh Chapel and Turner Pits [MDNR, 2007]. 

An independent study of the contamination confirmed that the elevated concentrations of 

sulfate and metals observed in the wells directly resulted from precipitation infiltrating the fly 

ash deposited in the BBSS sand and gravel mines [MDNR, 2007]. In October 2007, the 

Maryland Department of the Environment (MDE) fined Constellation and BBSS $1 million for 

the ground water contamination and required the companies to restore the local aquifer water 

quality [MDE, 2008]. In addition, Anne Arundel homeowners impacted by the contamination 

filed a class action lawsuit against Constellation and were awarded a $45 million settlement. The 

settlement required Constellation to pay the costs for converting 84 homes from well water to 

public water; cease future deliveries of new coal ash to the quarry; and to establish trust funds to 

compensate impacted property owners, enhance the neighborhood, and remediate and restore a 

former quarry site [Schultz, 2008]. 
Section 3 - Environmental And Human Health Concerns

3-40 

Virginia Power Yorktown Power Station Chisman Creek Disposal Site – Virginia

Between 1957 and 1974, Virginia Power’s Yorktown Power Station deposited fly ash in 

sand and gravel pits at the Chisman Creek Disposal Site. In 1974, the Yorktown Power Station 

discontinued disposal at the site because the plant began burning oil. 

In 1980, the water in a nearby shallow residential well turned green. Investigations in 

response to the drinking water discoloration determined that the residential well exceeded the 

primary MCL for selenium and found heavy metal contamination in the ground water around the 

fly ash disposal areas, in on-site surface impoundments, and in the sediments of Chisman Creek 

and its tributaries. 

In September 1983, EPA added the site to the National Priorities List under the 

Comprehensive Environmental Response, Compensation, and Liabilities Act (CERCLA). 

Cleanup began in late 1983 and included extending public water to 55 homes with contaminated 

well water, capping the disposal pits, collecting ground water and leachate for treatment, 

lowering the water table beneath the pits, and post-closure monitoring.

Ground Water Violations Near North Carolina Power Plants With Ash Ponds – North 

Carolina 

The North Carolina Department of Environment and Natural Resources reported ground 

water contamination near coal ash ponds at all 14 of the state’s coal-fired power plants. Duke 

Energy and Progress Energy each own seven of the plants and perform ground water monitoring 

as required by the state. Manganese and lead concentrations exceeded state ground water 

standards at all 14 locations and TDS and chromium exceeded state standards at seven locations. 

Boron levels at six of the facilities exceeded state ground water standards, and some facilities 

had elevated levels of arsenic, selenium, thallium, antimony, chlorides, and nickel. The state and 

plants have not identified the source of the contamination but noted that the exceedances 

occurred at newly located wells. Drilling the wells may have affected the concentration of 

naturally occurring elements such as lead and manganese [Ballard, 2012].20 

3.5.3 Potential for Impacts to Occur in Other Locations

Key environmental characteristics that contributed to the impacts documented in 

Sections 3.5.1 and 3.5.2, such as chronic exposure to large pollutant loadings, plants discharging 

to waters with long residence times, and no liners in surface impoundments or landfills, are 

common at steam electric power plants. This suggests that the impacts documented above 

indicate the greater potential threat combustion wastewater discharges pose to the environment. 

Although substantial events such as fish kills are well-documented, the extent to which more 

subtle damages, such as histopathological changes, morphological deformities, and damage to 

reproductive success, occur elsewhere is not known due to the limited extent of monitoring 

programs. 

 

20 EPA notes that the impacts reported at North Carolina plants have not been documented in a peer-reviewed 

literature source; however, the information shows that elevated levels of metal contamination can occur near ash 

ponds.
Section 3 - Environmental And Human Health Concerns

3-41 

The majority of the documented environmental impacts discussed above occurred 

following discharges of combustion wastewater under normal operations. Although the actual 

amounts of pollutant loadings discharged may vary among steam electric power plants, most of 

the documented case studies do not indicate that the pollutant loadings associated with the 

impacts are unusual for steam electric power plants. This suggests that chronic exposure to 

typical combustion wastewater pollutant loadings can impact the environment at other sites not 

documented in the literature. 

As discussed in Section 3.3, the residence time of combustion wastewater pollutants in 

surface water is a major factor in determining the impact to the environment and the length of the 

recovery time. Many documented case study sites are lentic water bodies such as lakes (i.e., still 

waters) where pollutants can reside for long periods of time. These types of receiving waters are 

at particular risk to impacts from combustion wastewater discharges. Steam electric power plants 

that discharge to a pond, lake, or reservoir may experience similar environmental effects as those 

observed in the documented case studies from analogous aquatic systems [U.S. EPA, 2013a]. 

According to the documented case studies, lack of a liner in surface impoundments and 

landfills is a significant factor in determining the extent of combustion wastewater impacts to 

ground water. Based on responses to the Steam Electric Survey, EPA identified 511 active 

surface impoundments and 153 active landfills containing combustion wastewater at steam 

electric power plants that currently do not have liners and may be contributing to similar ground 

water impacts documented in the case studies [U.S. EPA, 2013a]. 
Section 4—Exposure Pathways

4-1 

SECTION 4

EXPOSURE PATHWAYS

An exposure pathway is defined as the route a pollutant takes from its source (e.g., 

combustion residuals surface impoundments) to its endpoint (e.g., a surface water), and how 

receptors (e.g., fish, wildlife, or people) can come into contact with it. Exposure pathways are 

typically described in terms of five components: 

• Source of contamination. 

• Environmental pathway—the environmental medium or transport mechanism that 

moves the pollutant away from the source through the environment (e.g., discharges 

to surface waters).

• Point of exposure—the place (e.g., private drinking water well) where receptors (e.g., 

people) come into contact with a pollutant from the source of contamination. 

• Route of exposure—the way (e.g., ingestion, skin contact) receptors come into 

contact with the pollutant.

• Receptor population—the aquatic life, wildlife, or people exposed to the pollutant. 

The exposure pathway plays an important role in determining the potential effects of 

combustion wastewater on the environment. For example, the physical and chemical 

characteristics of receiving waters can affect the fate and transport of pollutants from combustion 

residuals surface impoundments to the environment and ultimately impact how the pollutants 

interact with the biological community. 

The U.S. Environmental Protection Agency (EPA) identified three primary exposure 

pathways of concern for combustion wastewater entering the environment: (1) discharges and 

leachate entering surface waters, (2) leaching 

to ground water, and (3) direct contact with 

combustion wastewater stored in surface 

impoundments. This section describes the 

factors that control the magnitude of 

combustion wastewater pollutant impacts to 

water quality, wildlife, and human health and 

presents EPA’s methodology for evaluating 

the national effect of combustion wastewater 

pollutants on the environment. Table 4-1

presents the environmental pathways, routes of 

exposure, and environmental concerns 

identified during the literature review and the 

type of analysis conducted to determine the 

impacts under baseline conditions and 

regulatory options. 

Pollutants from combustion wastewater stored in 

surface impoundments can reach receptor populations 

(such as wildlife or people) through various exposure 

pathways.
Section 4—Exposure Pathways

4-2 

Table 4-1. Combustion Wastewater Environmental Pathways and 

Routes of Exposure Evaluated in the EA

Environmental 

Pathway Route of Exposure Environmental Concern

Analysis to Determine 

Environmental Impact

Combustion wastewater

discharges to surface 

waters

Direct contact with surface 

water

Changes in surface water 

contamination levels

Water Quality Impacts 

(Quantitative)

Section 4.1.2

Direct contact with sediment Changes in sediment 

contamination levels

Wildlife Impacts 

(Quantitative)

Section 4.1.2 Consumption of 

contaminated fish

Bioaccumulation of 

contaminants in piscivorous

wildlife

Bioaccumulation of 

contaminants in fish 

consumed by humans

Human Health Impacts 

(Quantitative)

Section 4.1.2

Ingestion of contaminated 

surface water

Toxic effects on fish and 

aquatic life

Wildlife Impacts 

(Qualitative)

Sections 4.1

Combustion residuals

surface impoundment or 

landfill leachate 

infiltration to nearby 

surface waters

Direct contact with surface 

water or sediment

Changes in surface water 

and sediment contamination 

levels

Surface Water Impacts 

(Qualitative)

Section 4.1

Combustion residuals

surface impoundment or 

landfill leachate entering 

ground water

Ingestion of water Changes in ground water

quality

Ground Water Quality 

Impacts (Qualitative)

Section 4.2 Contaminated private 

drinking water wells

Combustion residuals

surface impoundment

Direct contact or ingestion 

of surface water

Toxic effects on wildlife Attractive Nuisances 

(Qualitative)

Section 4.3

Bioaccumulation of 

contaminants in wildlife

4.1 COMBUSTION WASTEWATER DISCHARGE AND LEACHATE ENTERING SURFACE

WATERS

Steam electric power plants commonly discharge combustion wastewater directly to 

surface waters following storage and treatment (e.g., particulate settling) in surface 

impoundments. At some steam electric power plants, wastewater and leachate collected from 

combustion residuals landfills and/or surface impoundments may be treated using advanced 

wastewater treatment systems that employ chemical precipitation or biological treatment prior to 

discharge back into a surface impoundment or to receiving water. In addition to effluent 

discharges, leachate from combustion residuals landfills and surface impoundments can migrate 

through the soil and into the receiving water. Further details on leachate are included in the 

discussion of the ground water environmental pathway in Section 4.2. 
Section 4—Exposure Pathways

4-3 

4.1.1 Factors Controlling Environmental Impacts in Surface Waters 

One of the primary factors controlling the environmental impact of combustion 

wastewater on surface waters is the residence time of the pollutants once they enter an aquatic 

system. Residence times are often determined by the flow rate of the receiving water and type of 

ecosystem it supports. The potential for pollutant retention in lentic aquatic systems (i.e., still or 

slow-moving water, such as lakes or ponds) and the creation of hot spots in lotic aquatic systems 

(i.e., flowing water, such as streams and rivers) are of particular concern when bioaccumulative 

pollutants are present. Many of the pollutants in combustion wastewater discharges 

bioaccumulate, which can further complicate estimates of potential impacts in surface waters 

because the pollutants can affect higher trophic levels, local terrestrial environments, and 

transient species, in addition to the aquatic organisms directly exposed to the wastewater. 

Based on results from EPA’s 2010 Questionnaire for the Steam Electric Power 

Generating Effluent Guideline (Steam Electric Survey),

21 EPA determined that 18 percent of 

aquatic environments that receive combustion wastewater discharges are lentic systems such as 

lakes, ponds, reservoirs, and estuaries (Table 4-2). The majority of ecological studies on the 

impact of combustion wastewater in aquatic environments have focused on lentic systems [Rowe 

et al., 2002]. In lentic aquatic systems, the hydraulic residence time, or the amount of time it 

takes for the water in the aquatic system to be replaced by inflowing streams or precipitation is 

relatively long, allowing pollutants to build up over time and making lentic systems more 

vulnerable to impacts from combustion wastewater. In addition, aquatic organisms are limited in 

their ability to avoid areas of high pollutant concentrations and are restricted to the food supply 

available only within the water body. 

Table 4-2. Final Outfall Receiving Water Types for Steam Electric Power Plants Within 

Scope of the Loadings Analysis 

Receiving Water Type

Number (Percentage) of Immediate 

Receiving Waters

River/stream 261 (82%)

Lake/pond 28 (9%)

Reservoir 8 (3%)

Great Lakes 14 (4%)

Estuary 6 (2%)

Total Receiving Waters 317 (100%)

Source: ERG, 2013l.

Based on results from EPA’s Steam Electric Survey, EPA determined that 82 percent of 

aquatic environments that receive combustion wastewater discharges are lotic systems such as 

rivers and streams [U.S. EPA, 2013a]. Lotic systems dilute discharges more quickly than lentic 

systems. The moving water in lotic systems also provides a transport mechanism to disperse 

pollutants greater distances from the power plant, and enables aquatic organisms to move away 

 

21 Results presented in this report are based on plant responses to the Questionnaire for the Steam Electric Power 

Generating Effluent Guidelines, which represent 2009 data.
Section 4—Exposure Pathways

4-4 

from the areas of combustion wastewater contamination [Rowe et al., 2002]. Although the 

discharge of combustion wastewater into a lotic system can distribute pollutants across a greater 

spatial area, changes in flow velocity may result in the concentration of pollutants at a single 

location further downstream [Rowe et al., 2002]. For example, combustion wastewater 

discharged to a river may encounter depositional areas of slower moving water downstream 

where pollutants would fall out of suspension and concentrate in a limited area. These pockets of 

higher pollutant concentrations, or hot spots, could be vulnerable to continued resuspension as 

stream velocities are affected by rainfall events, resulting in the pollutants being available to 

aquatic organisms over much longer periods of time [Lemly, 1997; Rowe et al., 2002]. 

4.1.2 Assessment of the Surface Water Exposure Pathway

EPA developed a receiving water model to quantify the environmental impacts to surface 

waters, wildlife, and human health from the waste streams evaluated for the regulatory options. 

As part of this national assessment, EPA determined impacts in the immediate surface water 

where steam electric industry discharges occur, between one and file miles from the outfall 

depending on the stream reach.22 As part of the benefits and cost analysis, EPA also evaluated 

surface water concentrations downstream from steam electric discharges using EPA’s RiskScreening Environmental Indicators (RSEI) model; see the Benefits and Cost Analysis for the 

Proposed Effluent Limitations Guidelines and Standards for the Steam Electric Power 

Generating Point Source Category (DCN SE03172) (Benefits and Cost Analysis). The 

framework focused on four key areas of impacts: 

• Impacts to aquatic life based on changes in water quality;

• Impacts to aquatic life based on changes in sediment quality; 

• Impacts to wildlife from consumption of contaminated fish; and 

• Impacts to human health from consumption of contaminated fish. 

EPA considered the type of receiving waters commonly impacted by steam electric 

power plants and the pollutants typically found in the evaluated waste streams in selecting the 

appropriate methodologies for the quantitative analysis. The receiving water model quantifies the 

environmental risks within 1) rivers/streams and 2) lakes/ponds (including reservoirs) based on 

the determination that almost 95 percent of the final outfall receiving water designations fell 

within these categories.23 

A key factor in determining the pollutants to include in the receiving water model was the 

dilution of discharges either by commingling cooling water with the evaluated waste streams 

prior to discharge or by the receiving water flows following discharge. For example, EPA 

 

22 See the ERG memorandum Water Quality Model: Plant and Receiving Water Characteristics (DCN SE01955) for 

details on the immediate discharge zone and length of stream reach represented.

23 The specific hydrodynamics and scale of the analysis required to appropriately model and quantify receiving 

water concentrations in the Great Lakes and estuary systems are more appropriately handled separately on a case 

study basis. EPA evaluated the impacts to the Great Lakes and Chesapeake Bay systems from a total mass loadings 

perspective in a separate qualitative analysis, discussed in Section 3.2. See the ERG memorandum Site-Specific 

Estuary Dilution Analysis (DCN SE02152) for details on EPA’s initial screening analysis of the modeled receiving 

water concentrations in the Great Lakes and estuary systems in comparison to water quality benchmarks. 
Section 4—Exposure Pathways

4-5 

determined that 58 percent of rivers and streams included in the model analysis had an average 

annual flow greater than 1,000 cubic feet per second. Due to the potential for dilution prior to 

discharge and in the receiving water, EPA focused the quantitative analysis on pollutants where 

the total mass loadings and not the concentration are critical factors in determining the potential 

for environmental impact. For the evaluated waste streams, nutrients and bioaccumulative metals 

represent the two primary pollutant categories considered for the receiving water model. 

Large amounts of nutrients entering a surface water can present an environmental 

concern. However, nutrient-related environmental problems (e.g., eutrophication) tend to be sitespecific depending on environmental factors (e.g., water-body temperature, the limiting nutrient 

in the system, algal species in the water body, availability of oxygen in the water) and are better 

evaluated on a case study basis. Therefore, EPA did not quantify surface water nutrient impacts 

for the receiving water quantitative analysis.24 EPA estimated total nitrogen and total phosphorus 

concentrations using dilution equations as input values to analyze benefits related to 

improvements in water quality. EPA used the SPARROW (SPAtially Referenced Regressions 

On Watershed attributes) model to provide baseline concentrations, as well as concentrations 

under each regulatory option. EPA used these concentrations to develop sub-indices for a water 

quality index (WQI), a value that translates water quality measurements, gathered for multiple 

parameters that represent various aspects of water quality, into a single numerical indicator. 

Total nitrogen and total phosphorous are only two of the sub-indices included in the WQI; the 

others are dissolved oxygen, biochemical oxygen demand, fecal coliform, total suspended solids 

(TSS), and heavy metals. EPA then used the WQI as a basis for calculating a willingness to pay 

for an increase in water quality as a result of the different regulatory options. See the Benefits 

and Cost Analysis for further details on the analysis and the results. 

EPA’s receiving water model includes three interrelated models: 

• Water quality model—calculates immediate receiving water specific metal 

concentrations in the water column and sediment and evaluates the impacts that 

receiving concentrations pose to aquatic life and human health.

• Wildlife model—evaluates the impact that sediment concentrations pose to aquatic 

life, calculates the metal concentrations in exposed fish populations, and evaluates the 

potential adverse effects to minks and eagles from consumption of fish. 

• Human health model—calculates non-cancer and cancer risks to human populations 

from the consumption of fish. 

The water quality model uses plant-specific input data (i.e., plant-specific pollutant 

loadings and cooling water flow rate),25 surface-water-specific characteristic data (e.g., receiving 

water flow rate, lake volume), and default assumption values to quantify the environmental 

impacts of the evaluated waste streams to surface waters. It calculates pollutant concentrations in 

 

24 EPA qualitatively evaluated the potential environmental impact of nutrients within the context of the total mass 

nutrient loadings entering the Great Lakes and Chesapeake Bay from steam electric power plants (see Section 3.2).

25 EPA calculated pollutant loadings for the evaluated waste streams and excluded any pollutants discharged with 

other wastewaters (e.g., coal pile runoff). EPA incorporated cooling water flow rates into the water quality model on 

a site-by-site basis. EPA assumed no pollutant loadings were associated with cooling water discharges to surface 

waters.
Section 4—Exposure Pathways

4-6 

the surface water and sediment. These concentrations are inputs for the wildlife model, which 

calculates the bioaccumulation of pollutants in fish tissue and determines impacts to wildlife. 

The fish tissue concentration calculated in the wildlife model is an input to the human health 

model. This section provides overviews of each model. Appendices C through E describe the 

model calculations, inputs, and assumptions in further detail. The Appendices also describe the 

limitations and assumptions of the models. Figure 4-1 provides an overview of the model inputs 

and the connections among the three models to support EPA’s national-scale modeling 

framework. 

Figure 4-1. Overview of Receiving Water Model 

Water Quality Model 

As discussed above, EPA focused the quantitative analysis on the mass of pollutants 

discharged to determine the potential for environmental impact. EPA selected the steady-state 

equilibrium-partitioning model described in EPA’s Methodology for Assessing Health Risks 

Associated with Indirect Exposure to Combustor Emissions (EPA 600-R-98-137) for the water 

quality model. This selection was based on three factors: the model’s ability to represent metals 

in the aquatic environment, model complexity judged to be appropriate for a national-scale 

evaluation,

26 and level of previous Agency and external peer reviews performed on the modeling 

methodology. An equilibrium-partitioning model assumes that dissolved and sorbed metals in a 

receiving water will quickly attain equilibrium in the immediate vicinity of the discharge point 

 

26 For a national-scale environmental assessment of nearly 300 receiving waters, data limitations inhibit the 

feasibility of using more complex fate and transport receiving water models (dynamic or hydrodynamic) to estimate 

surface water concentrations.
Section 4—Exposure Pathways

4-7 

by assuming that sorption reactions in the surface water are fast relative to transport or dispersion 

of the metal outside the immediate area. The model also assumes that the equilibrium state for 

each metal can be represented by a partition coefficient that divides the total mass of a metal in 

the water body into four compartments: 

• Constituents dissolved in the water column; 

• Constituents sorbed onto suspended solids in the water column; 

• Constituents sorbed onto sediments at the bottom of the water body; and 

• Constituents dissolved in pore water in the sediments at the bottom of the water body. 

Table 4-3 lists the metals commonly found in the evaluated waste streams with known 

environmental impacts (see Section 3.1, Table 3-1). EPA selected a subset of these metals for the 

water quality model based on a combination of the following criteria:

• The metal is known to be present in the evaluated waste streams.

• Scientific literature documents elevated levels observed in surface waters or wildlife 

from exposure to combustion wastewater. 

• Partition coefficient data were available for the water quality model. 

• Benchmarks are available to determine impact risks to wildlife or human health.

For the receiving water quality analysis, EPA modeled 10 of the metals shown in Table 

4-3: arsenic, cadmium, chromium VI, copper, lead, mercury, nickel, selenium, thallium, and 

zinc. These metals include the six metals with the highest toxic weighting factors (TWFs) (see 

Table 3-2)—arsenic, cadmium, lead, mercury, selenium, and thallium; along with discharges of 

four additional metals known to bioaccumulate in aquatic organisms: chromium VI, copper, 

nickel, and zinc. Although EPA identified manganese and boron in the top three pollutants with 

the highest toxic weighted pound equivalents (TWPEs) for baseline pollutant loadings (see Table 

3-2), EPA did not include these metals in the model due to lack of partition coefficient data and 

limited threshold criteria data for comparison. EPA identified total dissolved solids (TDS) and 

chlorides as the pollutants with the largest loadings under baseline conditions (see Table 3-2); 

however, EPA did not include these pollutants in the receiving water model for several reasons. 

TDS from the evaluated waste streams consists largely of dissolved metals that are already 

captured in the receiving water model. Therefore, estimates of potential environmental impacts 

from TDS would double-count many of the environmental impacts and potential improvements 

assessed. Chlorides lack partition coefficient data and have limited numeric threshold criteria 

data for comparison. 
4-8

Section 4—Exposure Pathways

Table 4-3. Metals Considered for Analysis in the Receiving Water Model

Pollutant

Literature 

Review a

Partition 

Coefficient b NRWQC c

Maximum 

Contaminant 

Level (MCL)

Wildlife 

Benchmark d

Human Health 

Benchmark e

Included in 

Modeling 

Analysis f

Aluminum  

Arsenic g       

Boron  

Cadmium       

Chromium h       

Copper       

Iron  

Lead     

Manganese  

Mercury i       

Nickel      

Selenium j       

Thallium     

Vanadium   

Zinc     

a – Literature review identified documented cases of elevated levels in surface waters or wildlife near steam electric power plants [ERG, 2013b]. 

b – Partition coefficients for modeling analysis identified in U.S. EPA, 1999, and U.S. EPA, 2005a. 

c – Aquatic life or human health National Recommended Water Quality Criteria (NRWQC) available at 

http://water.epa.gov/scitech/swguidance/standards/current/index.cfm.

d – No effect hazard concentration (NEHC) identified in USGS, 2008, for minks and bald eagles.

e – Reference dose (RfD) identified in EPA’s Integrated Risk Information System (IRIS) for all pollutants except copper and thallium (available at 

http://www.epa.gov/iris/); RfD for copper is the intermediate oral minimal risk level (MRL) [ATSDR, 2010a]; and RfD for thallium is the value for thallium 

chloride provided in U.S. EPA, 2010a. Cancer slope factor for arsenic identified in EPA’s IRIS database [2011]. 

f – Metal is included in the quantitative modeling analysis discussed in this section.

g – Arsenic exists in two primary forms: arsenic III and arsenic V. Check marks were included for total arsenic, arsenic III, and arsenic V. 

h – Chromium exists in two primary forms: chromium III and chromium VI. Check marks were included for total chromium and chromium VI. 

i – Check marks were included for mercury and methylmercury.

j – Selenium exists in two primary forms: selenate and selenite. Check marks were included for total selenium, selenate, and selenite. 
Section 4—Exposure Pathways 

4-9 

EPA developed the water quality model in Microsoft AccessTM using the equilibriumpartition equations presented in Appendix C. The water quality model is a mathematical model 

used to represent the partitioning of pollutants through the surface water after the combustion 

wastewater has been discharged. The model output provides site-specific pollutant 

concentrations in the water column (total, dissolved, and suspended) and sediment for all steam 

electric power plants located across the United States that discharge to a river or stream or to a 

lake, pond, or reservoir. Figure 4-2 depicts the pollutant concentrations calculated in the water 

quality model. EPA implemented this modeling approach through the following steps: 

1. Characterize the immediate receiving water characteristics (e.g., depth of water 

column, depth of water body, receiving water width, and flow independent mixing 

value) using site-specific inputs. See the ERG memorandum Water Quality Model: 

Plant and Receiving Water Characteristics (DCN SE01955). 

2. Using the immediate receiving water characteristics, determine the fraction of 

pollutant in the benthic sediment and in the water column and determine fraction of 

pollutant in the water column that is dissolved. 

3. Using the immediate receiving water characteristics and assumed input values, 

calculate the water column volatilization rate constant (for volatile metals only – i.e., 

mercury).

4. Calculate the water concentration dissipation rate (zero for nonvolatile metals).

5. Based on site-specific pollutant loadings, cooling water flow rates (for a subset of 

plants), and immediate receiving water characteristics, calculate the total pollutant 

concentrations (e.g., total arsenic) in the immediate receiving water, including the 

concentration in the water column and in the benthic sediment. The model also 

calculates the concentration of dissolved pollutant in the water column. Section 10 of 

the Technical Development Document for the Proposed Effluent Limitations 

Guidelines and Standards for the Steam Electric Power Generating Point Source 

Category (TDD) (DCN SE01964) details the pollutant loadings methodology; the 

ERG memorandum Water Quality Model: Plant and Receiving Water Characteristics

(DCN SE01955) describes the use of cooling water flow rates. Note that the metal

loadings included in the model are not representative of the total metal loadings from 

steam electric power plants; several waste streams were not evaluated (e.g., 

stormwater runoff, metal cleaning wastes, coal pile runoff). 

6. Quantify the number of sites that exceed the National Recommended Water Quality 

Criteria (NRWQC) and drinking water maximum contaminant levels (MCLs) to 

evaluate the potential exposure of ecological receptors (i.e., aquatic biota) and human 

receptors to toxic pollutants in the environment from the evaluated waste streams. 
Section 4—Exposure Pathways 

4-10 

Source: U.S. EPA, 1998b

Figure 4-2. Water Quality Model: Pollutant Fate in the Water Body 

As an indicator of potential impacts, EPA compared baseline and regulatory option 

immediate receiving water concentrations to the following NRWQC: 

• Freshwater acute and chronic aquatic life NRWQC;

• Human health NRWQC for the consumption of water and organisms; and

• Human health NRWQC for the consumption of organisms. 

EPA also compared immediate receiving water concentrations to drinking water MCLs. 

EPA identified immediate receiving waters that exceeded a NRWQC or MCL as an indication of 

the degradation of the overall water quality following exposure to the evaluated waste streams. 

Section 5.3 summarizes the NRWQC and MCL exceedances under baseline pollutant loadings. 

Section 6.2 presents the percent reduction in number of immediate receiving waters that 

potentially impact water quality under the regulatory options. 

As with any modeling, EPA recognizes that model limitations exist and certain 

assumptions need to be made. EPA used average annual pollutant loadings and effluent flow

rates, which do not take into account temporal variability (e.g., seasonal differences, storm flows, 

low flow events, catastrophic events). Model-specific limitations and assumptions are included 

in Appendix C of this report. The results of the water quality model are included in Section 5 and 

Section 6 of this report. 

Wildlife Model

As shown in Figure 4-1, the wildlife model builds off the water quality model by using 

the calculated immediate receiving water and sediment concentrations to calculate metal 

Mass Load Discharged 

from Evaluated Waste 

Streams

Volatilization

Bottom (Benthic) 

Sediment

Water Column

Degradation

Burial

Cwc Csw

Cdw 

Cbs

CwTot = Cwc + Cbs

Cooling Water

from Plant (if 

applicable)

Pollutant concentration (C) is calculated 

by the water quality model using average 

annual flow rate of the receiving water 

(and cooling water flow rate where 

applicable)

Equilibrium Reaction

Cwc– Concentration 

in the water column

Cdw – Concentration 

that is dissolved in 

the water

Csw – Concentration 

that is suspended in 

the water

CwTot – Concentration 

in the water body

Cbs– Concentration 

sorbed to bottom (or 

benthic) sediment
Section 4—Exposure Pathways 

4-11 

concentrations in fish populations exposed to the evaluated waste streams and to assess the 

potential to impact wildlife for the following categories: 

• Impact to aquatic organisms from contact with sediment contaminated by the 

evaluated waste streams by quantifying the number of sites with potential exposure of 

ecological receptors (i.e., sediment biota) to the pollutant in the environment; and 

• Impact to piscivorous wildlife (i.e., wildlife that habitually feeds on fish) from 

consuming fish impacted by the evaluated waste streams by quantifying the number 

of sites with potential exposure of ecological receptors (i.e., piscivorous wildlife) to 

the pollutant in the environment. 

EPA developed the wildlife model in Microsoft AccessTM to calculate metal

concentrations in fish populations exposed to the evaluated waste streams and estimate daily 

contaminant dose for wildlife receptors (e.g., minks and eagles) using equations presented in 

Appendix D. The wildlife model derives an indicator of potential impacts to wildlife by

comparing the concentration in the contaminated media (i.e., water, sediment, or fish) to 

concentrations known to have impact (i.e., benchmark). Benchmarks are pollutant- and endpointspecific and sometimes are species-specific. Benchmarks are an expression of the concentration 

level in contaminated media that is protective against a specific endpoint (e.g., mortality). 

Endpoints frequently reflected in benchmark values include sublethal effects such as reduced 

reproduction, neurological effects, and lethal effects. In the wildlife model, the potential impact

to wildlife is expressed in terms of a hazard quotient (HQ). An HQ is the ratio of concentration 

in contaminated media to a concentration benchmark. An HQ of 1 is defined as the highest 

pollutant concentration at which no adverse health effects are likely to occur. Therefore, an HQ 

greater than 1 indicates a potential impact to wildlife for the endpoint associated with the 

benchmark value used in the HQ analysis. For example, if the HQ for mercury for eagles is 

greater than one, then there is a potential threat for their reproductive health to be impacted. 

EPA implemented the wildlife modeling approach through the following steps: 

1. Calculate the pollutant concentration in fish for trophic level three (T3) or trophic 

level four (T4),27 using the calculated pollutant concentration in the water column and 

the bioconcentration factor (BCF). For mercury, calculate the concentration of 

methylmercury in the fish. See Appendix D. 

2. Calculate the HQs for ecological receptors (sediment biota, mink, and eagle). 

3. Compare the baseline and regulatory option results: number of sites with potential 

exposure of ecological receptors to concentrations with potential impacts. 

Adverse Effects to Aquatic Organisms from Contact with Sediment. The wildlife 

model calculates HQs for benthic organisms exposed to metal sediment concentrations 

calculated in the water quality model. EPA used benchmarks provided in the National Oceanic 

and Atmospheric Administration (NOAA) 2008 Screening Quick Reference Tables (SQuiRTs), 

 

27 T3 fish (e.g., carp, smelt, perch, catfish, sucker, bullhead, sauger) are those that consume invertebrates and 

plankton, while T4 fish (e.g., salmon, trout, walleye, bass) are those that consume other fish.
Section 4—Exposure Pathways 

4-12 

referred to as the chemical stressor concentration limit (CSCL), for the sediment biota HQ 

calculations. The CSCL is a chemical-specific media concentration that is protective of 

ecological receptors of concern. The CSCL benchmark is species-specific, but can be used to 

represent a community of organisms, such as amphibians or fish. Usually the most sensitive (or 

lowest) CSCL for a species is used to represent the community. Table D-1 presents the CSCL 

benchmarks used for sediment exposure analysis. The results of this analysis for baseline 

pollutant loadings are discussed in Section 5.3.2 of this report. 

Assessment of Pollutant Bioconcentration in Fish. EPA calculated fish tissue 

concentrations based on 1) total water column concentrations (i.e., dissolved plus sorbed) 

calculated in the water quality model and 2) trophic-level-specific BCFs. BCFs are based on the 

compilation of field and laboratory study results to develop a single factor or ratio for estimating 

the amount of pollutant transferred into fish tissue at a given trophic level (i.e., rank in the food 

chain) based on the pollutant concentration in the water body. EPA estimated fish tissue 

concentrations in milligrams per kilogram (mg/kg) for T3 and T4 fish to account for the 

variability in fish likely consumed by both wildlife and human receptors included in the 

receiving water model. 

Although using the total water body concentration in the BCF analysis may overestimate 

the level of metals in the fish, it provides for a more environmentally protective estimate of risk 

in the subsequent human health model because it assumes that all metals within the water body 

(both dissolved and sorbed) are bioavailable to the exposed fish. The exception to this 

methodology is mercury, where EPA based the fish tissue concentration calculation on the 

dissolved concentration of methylmercury in the water body [U.S. EPA, 2005b]. Appendix D 

presents the BCFs and model equations for the analysis of metal bioconcentration in fish tissue 

for T3 and T4 fish. 

Impact to Piscivorous Wildlife. EPA based the piscivorous wildlife impact analysis on 

the methodology outlined in the 2008 U.S. Geological Survey (USGS) study Environmental 

Contaminants in Freshwater Fish and Their Risk to Piscivorous Wildlife Based on a National 

Monitoring Program. The study examined the impacts to minks and eagles from eating 

contaminated fish. Minks and eagles are commonly used in ecological risk assessments as 

indicator species for potential impacts to fish-eating mammals and birds in areas contaminated 

with bioaccumulative pollutants [USGS, 2008]. Minks and eagles are appropriate receptors for 

the steam electric wildlife impact analysis because their habitats span most of the country and 

their diet largely consists of adult fish from the two trophic levels (i.e., T3 and T4 fish) 

calculated in the wildlife model. According to the literature [U.S. EPA, 1998a], minks consume 

mostly T3 fish, while eagles consume mostly T4 fish. EPA evaluated the potential adverse 

effects to minks and eagles for nine metals commonly found in the waste streams of interest: 

arsenic, cadmium, chromium,28 copper, mercury,29 nickel, lead, selenium, and zinc. The USGS 

method [USGS, 2008] is a wildlife impact analysis using NOAELs (no-observed-adverse-effect 

levels), which were derived from adult dietary exposure or tissue concentration studies based 

 

28 Because there is no benchmark for chromium VI, EPA used the total chromium benchmark, which may 

underestimate the risk to wildlife.

29 Because there is no benchmark for methyl mercury, EPA used the total mercury benchmark, which may 

underestimate the risk to wildlife.
Section 4—Exposure Pathways 

4-13 

primarily on reproductive endpoints. The study calculated a benchmark called the no effect 

hazard concentration (NEHC), which is based on the NOAEL, the food consumption rate, and/or 

the biomagnification factor of each receptor. The report states that piscivorous wildlife may be at 

risk for reduced reproduction rates if the measured metal concentration in fish exceeds the 

NEHC. Therefore, EPA calculated an HQ for minks using the mink-specific NEHC values from 

the USGS study for comparison with the T3 fish tissue concentrations. EPA also calculated an 

HQ for eagles using the eagle-specific NEHC values from the USGS study for comparison with 

the T4 fish tissue concentration. In the piscivorous wildlife analysis, an HQ greater than one 

indicates that piscivorous mammals or birds exposed to fish in the immediate receiving water of 

interest are at risk for reduced reproduction rates or other health effects.

Table D-3 presents the NEHC values used to evaluate potential adverse effects to 

wildlife; the text of Appendix D presents the equations used to compare model outputs to 

benchmarks (NEHCs), along with model-specific limitations and assumptions. The results of the 

wildlife model are included in Section 5 and Section 6 of this report. 

Human Health Model 

As shown in Figure 4-1, the human health model builds off the wildlife model, using the 

calculated T3 and T4 fish tissue concentrations. Its purpose is to evaluate the cancer risk and 

potential to cause non-cancer health effects from the consumption of fish within the following 

age and consumption categories: 

• Child recreational fishers; 

• Child subsistence fishers; 

• Adult recreational fishers; and

• Adult subsistence fishers. 

EPA developed the human health model in Microsoft AccessTM to estimate the daily 

contaminant (i.e., metal) doses for human receptors as a result of eating T3 and T4 contaminated 

fish. EPA used a mathematical model to estimate the potential threats to human receptors from 

pollutant exposure. EPA estimated the average concentration of metals in a fish filet consumed 

by humans based on a consumption diet of 36 percent T3 and 64 percent T4 fish (see 

Appendix E). The human health model then calculates the daily dose of metals from fish 

consumption for each human cohort (i.e., recreational and subsistence fishers, child or adult) 

included in the analysis.30 EPA varied the fish consumption rate and body weight of each cohort 

based on age to determine a daily metal dose for each human cohort evaluated. Table E-2 

presents the human cohorts included in the human health model and the corresponding fish 

consumption rates and body weights used in the model. EPA implemented the human health 

modeling approach through the following steps: 

1. Calculate the pollutant concentration in a fish filet.

 

30 The child cohort age ranges correspond to the ranges provided in the 2008 Child-Specific Exposure Factors 

Handbook (EPA-600-R-06-096F) for body weights.
Section 4—Exposure Pathways 

4-14 

2. Calculate daily dose of pollutant from fish consumption by each receptor cohort (used 

for comparison to reference dose [RfD] values). 

3. Calculate the lifetime average daily dose (LADD) for carcinogenic pollutants only, by 

each receptor cohort (used to determine cancer risk). 

4. Calculate the lifetime excess cancer risk (LECR) for carcinogenic pollutants only, by 

each receptor cohort, using the LADD. 

5. Compare the exposure doses of human receptor cohorts to appropriate benchmarks 

(RfD and selected cancer benchmark: 1-in-a-million).

6. Compare the baseline and regulatory option results: reduction in the number of 

immediate receiving waters with exposure doses from the consumption of fish that 

pose a potential threat to human receptors. 

Non-Cancer Threat to Human Receptors. EPA evaluated the non-cancer threat (e.g., 

reproductive or neurological impacts) to each human cohort by calculating an HQ based on the 

comparison of the metal-specific daily dose values for fish consumption to RfDs. EPA evaluated 

non-cancer risks for the following metals: inorganic arsenic,

31 cadmium, chromium VI, copper, 

methylmercury, nickel, selenium, thallium, and zinc. Table E-3 in Appendix E presents the RfD 

values used in the non-cancer threat analysis. RfD values are an expression of the consumption 

dose that is protective against a specific endpoint. Endpoints frequently reflected in RfDs include 

various immunological, reproductive, neurological, and other non-cancer effects. In the human 

health model, the potential impact to humans is expressed in terms of an HQ. An HQ of 1 is 

defined as the highest consumption dose at which no adverse health effects are likely to occur. 

Therefore, an HQ greater than 1 indicates a potential threat to humans for the endpoint associated 

with the RfD value used in the HQ analysis. For example, an HQ greater than 1 for selenium 

indicates that the exposure dose from fish consumption has the potential to cause non-cancer 

health effect, such as selenium-induced liver dysfunction or selenosis (hair or nail loss, 

morphological changes of the nails, etc.) [U.S. EPA, 2011c]. 

Cancer Risk to Human Receptors. Arsenic is the only pollutant32 included in the 

receiving water model for which EPA has derived a cancer slope factor for ingestion exposures. 

The human health model calculates the LADD for each receptor cohort based on an exposure 

duration (i.e., length of time a receptor is in contact with the carcinogen) averaged over a lifetime 

 

31 For this analysis, EPA decided to use only the concentration of inorganic arsenic for the human health impact 

assessment. Based on the literature review, arsenic in fish is mostly in the organic form and is not considered 

harmful. The wildlife model calculates a total arsenic fish tissue concentration. To convert this number to inorganic 

arsenic, EPA assumed that 4 percent of the total arsenic is inorganic based on EPA’s 1997 document, Arsenic and 

Fish Consumption (EPA-822-R-97-003). The 1997 document reported that the inorganic arsenic concentration in 

fish is between 0.4 and 4 percent of the total arsenic accumulating in fish [U.S. EPA, 1997b]. 

32 Although EPA has determined that lead and lead compounds can be “reasonably anticipated to be human 

carcinogens,” no numeric value has been determined to quantify the cancer risk. As stated on the IRIS website, 

“quantifying lead’s cancer risk involves many uncertainties, some of which may be unique to lead. Age, health, 

nutritional state, body burden, and exposure duration influence the absorption, release, and excretion of lead. In 

addition, current knowledge of lead pharmacokinetics indicates that an estimate derived by standard procedures 

would not truly describe the potential risk. Thus, the Carcinogen Assessment Group recommends that a numerical 

estimate not be used.” (see http://www.epa.gov/iris/subst/0277.htm#reforal)
Section 4—Exposure Pathways 

4-15 

(i.e., 70 years). For this analysis, EPA assumed the exposure duration to be equal to the number 

of years represented by each cohort. The use of these exposure durations is appropriate for 

screening-level estimates of cancer risk and to compare changes between baseline and regulatory 

options.33 The model then multiplies the LADD by the cancer slope factor to calculate the LECR

from arsenic. LECR is an estimate of the increase in cancer risk resulting from an exposure (i.e., 

consumption of contaminated fish). EPA used the benchmark value for evaluating cancer risk of 

one in 1,000,000 people. Therefore, a calculated LECR greater than 1 × 10-6 indicates 

carcinogenic human health impacts from the 

consumption of fish exposed to discharges of 

evaluated waste streams. 

4.2 LEACHING TO GROUND WATER

Combustion residual landfills and 

surface impoundments can impact local ground 

water through leaching. Once in ground water, 

pollutants can migrate from the site and

contaminate public or private drinking water 

wells and surface waters [NRC, 2006]. The fate 

of combustion residuals pollutants in ground 

water is controlled by many biological and 

geochemical (e.g., adsorption, desorption, and 

precipitation reactions with aquifer materials) 

processes that can vary over large spatial and 

temporal scales [NRC, 2006]. This section describes the pollutant concentrations, chemical 

characteristics (e.g., solubility, leachability, persistence, and mobility) and fate and transport 

processes that influence the potential impact of leachate from combustion residuals landfills and 

surface impoundments on the environment. 

4.2.1 Factors Controlling Environmental Impacts to Ground Water 

Environmental impacts to ground water are determined by the pollutant concentrations in 

the leachate and the rate of pollutant transport in the ground water. The pollutant concentrations 

in the leachate depend on factors including characteristics of the combustion residuals, site 

conditions (e.g., rainfall amount and pH of the pore water in the surface impoundment or 

landfill), and combustion residuals residence time in the surface impoundment or landfill.34 The 

rate of pollutant transport in ground water depends on factors such as the biogeochemical 

characteristics of the subsurface (e.g., soil pH and oxidation-reduction potentials), local rates of 

ground water recharge, and unsaturated and saturated ground water flow velocities.

 

33 For a complete assessment of risk to an individual, EPA recommends that risks should be calculated by 

integrating exposures throughout all life stages (i.e., adding multiple cohort risks from screening analysis). The 

exposure duration may be equal to the length of time a person lives in an area [U.S. EPA, 2011b].

34 Leaching experiments indicate that the chemistry of leachates are based on both the chemical composition of the 

waste and other factors such as site conditions [Thorneloe et al., 2010]. Thorneloe [2010] specifically looked at fly 

ash and bottom ash waste from coal-fired power plants.

Most surface impoundments are unlined, allowing 

pollutants to infiltrate into ground water and eventually 

into surface waters.
Section 4—Exposure Pathways 

4-16 

Pollutant Concentrations in Leachate 

Combustion residuals characteristics include the mineralogy of the waste (e.g., lime, 

gypsum, iron, and aluminum oxide content) and pollutant solubility in the pore water. The 

mobility of metals may be altered due to changes in pH, carbon and chloride content, and 

interaction with other wastes from steam electric power plants [Thorneloe, 2010]. The waste 

mineralogy can vary based on the chemical composition in the fuel source (e.g., the specific coal 

seam and geographic location of the mine) and operational characteristics at the plant. Many 

laboratory investigations have examined the solubility characteristics of various pollutants 

associated with fly ash [Prasad, 1996; Thorneloe, 2010]. The results of these investigations 

largely depend on multiple factors, and they tend to be more applicable qualitatively rather than 

quantitatively e.g., results from investigations can be used to determine the likelihood of a 

pollutant to dissolve in the leachate, but not the amount). Concentrations of inorganic pollutants 

derived from calcium, sodium, magnesium, potassium, iron, sulfur, and carbon are relatively 

high in aqueous solution of fly ash, because of their high total concentrations in the ash [Prasad 

et al., 1996]. 

The pH of the pore water is a dominant factor in the leaching of pollutants from surface 

impoundments and landfills. Because most metals in combustion residuals exhibit weak acid or 

weak base behavior in aqueous solution, the pore water pH strongly influences the concentration 

of metal in the leachate. Steam electric power plants generate combustion residuals in hightemperature processes, and many acidic species (e.g., carbon dioxide, hydrogen sulfide, 

hydrochloric acid) are volatilized prior to waste collection. Therefore, combustion residuals 

would be expected to yield an alkaline reaction in water; this is the case, but acidic reactions 

have also been observed [Theis et al., 1990]. Acidic pore water allows metals from the 

combustion residuals to remain in solution, increasing their mobility and the potential for ground 

water contamination. From a study of three power plants in Turkey, the results indicated that 

combustion residuals in the deeper layers of landfills and on the bottoms of the surface 

impoundments may continue to leach if the pH value drops in the surrounding environment 

[Baba and Kaya, 2004].35 Table 4-4, Table 4-5, and Table 4-6 present data collected by EPA’s 

Steam Electric Survey showing metal pollutant concentrations in the leachate for acidic, neutral, 

and basic conditions. 

 

35 This conclusion was based on a comparison of ash extraction procedures used. The study examined how the 

concentration of trace elements in the ash can vary based on the procedure used, comparing the EPA-developed EP

(extraction procedure) and its replacement method, TCLP (toxicity characteristic leaching procedure), and the 

ASTM (American Society for Testing and Materials) Method D-3987. A comparison of the results revealed that the 

ASTM procedure indicated much lower dissolved metal concentrations than the EP and TCLP procedures. These 

results indicate that pH is an important parameter affecting the leaching rate of metals from ash deposits. The lower 

pH values in the EP and TCLP methods increase the leaching rate of inorganic constituents of fly ash and bottom 

ash [Fleming et al., 1996].
Section 4—Exposure Pathways 

4-17 

Table 4-4. Metal Concentrations in Leachate Under Acidic Conditions (pH of 1.0 to 6.5)

Pollutant

Minimum 

Concentration 

in Leachate 

(mg/L)

Maximum 

Concentration 

in Leachate 

(mg/L) MCL (mg/L)

Number of Samples 

Exceeding MCL 

(Total Number of 

Samples)

Percentage of 

Samples 

Exceeding 

MCL

Arsenic 1.00 x 10-3 0.301 0.01 15 (21) 62%

Boron 0.137 55.1 7 a 3 (21) 14%

Cadmium 3.07 x 10-5 1.87 x 10-2 0.005 6 (21) 29%

Chromium 1.00 x 10-4 1.68 x 10-2 0.1 0 (21) 0%

Copper 1.60 x 10-4 0.110 1.3 0 (21) 0%

Lead 5.00 x 10-6 1.62 x 10-2 0.015 1 (21) 5%

Manganese 3.75 x 10-2 86.8 0.05 b 20 (21) 95%

Mercury 2.00 x 10-7 7.51 x 10-2 0.002 1 (21) 5%

Nickel 3.92 x 10-3 1.26 No MCL NC (21) NC

Selenium 1.00 x 10-4 0.143 0.05 3 (21) 14%

Thallium 2.10 x 10-5 1.74 x 10-2 0.002 11 (21) 52%

Zinc 5.00 x 10-3 3.32 5 b 0 (21) 0%

Source: ERG, 2013g. 

Acronyms: mg/L (milligrams per liter); MCL (Maximum Contaminant Level); NC (not calculated; no MCL for 

comparison). 

Note: Data are for untreated leachate at steam electric landfills and surface impoundments.

a – The drinking water equivalent level, used for noncarcinogenic endpoints, is listed rather than the MCL.

b – MCL is a secondary (nonenforceable) standard. 

Table 4-5. Metal Concentrations in Leachate Under Neutral Conditions (pH of 6.5 to 7.5)

Pollutant

Minimum 

Concentration 

in Leachate 

(mg/L)

Maximum 

Concentration 

in Leachate 

(mg/L)

MCL 

(mg/L)

Number of Samples 

Exceeding MCL 

(Total Number of 

Samples)

Percentage of 

Samples 

Exceeding MCL

Arsenic 6.00 x 10-5 0.202 0.01 19 (64) 30%

Boron 7.36 x 10-4 236 7 a 20 (64) 31%

Cadmium 2.00 x 10-5 1.28 x 10-2 0.005 2 (63) 3%

Chromium 4.00 x 10-5 2.72 x 10-2 0.1 0 (64) 0%

Copper 1.30 x 10-4 1.50 x 10-2 1.3 0 (64) 0%

Lead 1.00 x 10-5 2.50 x 10-3 0.015 0 (62) 0%

Manganese 2.00 x 10-4 8.64 0.05 b 52 (64) 81%

Mercury 1.50 x 10-7 0.190 0.002 10 (64) 16%

Nickel 9.00 x 10-5 0.162 No MCL NC (64) NC

Selenium 7.00 x 10-5 2.03 0.05 11 (64) 17%

Thallium 2.00 x 10-5 7.00 x 10-3 0.002 6 (62) 10%

Zinc 9.00 x 10-4 3.95 5 b 0 (63) 0%

Source: ERG, 2013g. 

Acronyms: mg/L (milligrams per liter); MCL (Maximum Contaminant Level); NC (Not Calculated; no MCL for 

comparison). 

Note: Data are for untreated leachate at steam electric landfills and surface impoundments.

a – The drinking water equivalent level, used for noncarcinogenic endpoints, is listed rather than the MCL.

b – MCL is a secondary (nonenforceable) standard. 
Section 4—Exposure Pathways 

4-18 

Table 4-6. Metal Concentrations in Leachate Under Basic Conditions (pH of 7.5 to 14)

Pollutant

Minimum 

Concentration 

in Leachate 

(mg/L)

Maximum 

Concentration 

in Leachate 

(mg/L)

MCL 

(mg/L)

Number of Samples 

Exceeding MCL 

(Total Number of 

Samples)

Percentage of 

Samples 

Exceeding MCL

Arsenic 6.00 x 10-5 0.25 0.01 64 (90) 71%

Boron 2.88 x 10-3 93.2 7 a 28 (91) 31%

Cadmium 1.00 x 10-5 0.39 0.005 26 (90) 29%

Chromium 1.00 x 10-4 2.2 0.1 16 (90) 18%

Copper 5.00 x 10-5 4.40 x 10-2 1.3 0 (91) 0%

Lead 9.00 x 10-6 0.49 0.015 2 (86) 2%

Manganese 2.00 x 10-4 4.37 0.05 b 48 (89) 54%

Mercury 2.00 x 10-7 6.90 x 10-2 0.002 7 (89) 8%

Nickel 9.00 x 10-5 7.94 x 10-2 No MCL NC (87) NC

Selenium 7.00 x 10-5 0.425 0.05 28 (90) 31%

Thallium 2.00 x 10-5 5.00 x 10-2 0.002 12 (86) 14%

Zinc 1.00 x 10-4 7.73 x 10-2 5 b 0 (86) 0%

Source: ERG, 2013g. 

Acronyms: mg/L (milligrams per liter); MCL (Maximum Contaminant Level); NC (Not Calculated; no MCL for 

comparison). 

Note: Data are for untreated leachate at steam electric landfills and surface impoundments.

a – The drinking water equivalent level, used for noncarcinogenic endpoints, is listed rather than the MCL.

b – MCL is a secondary (nonenforceable) standard. 

As Table 4-4, Table 4-5, and Table 4-6 show, acidic conditions can lead to higher 

concentrations in the leachate for the following pollutants in combustion wastewater—arsenic, 

copper, manganese, nickel, and zinc. The solubility of most trace metals (the notable exceptions 

being arsenic and selenium) tends to decrease with increased pH (i.e., alkaline conditions). 

Chromium was the only metal with a concentration range that skewed higher at basic conditions. 

Arsenic, which had a higher concentration range at acidic conditions, exceeded its MCL in both 

acidic and basic leachate (due to its higher solubility in alkaline conditions). Similarly, 

manganese exceeded its secondary MCL under all pH conditions. Selenium had varying 

concentrations under all pH conditions, but exceeded its MCL more frequently under basic 

conditions. Overall, results are as expected based on the literature data – more leaching (i.e., 

higher concentration) of metals in acidic conditions.

In addition to the pH of the pore water, amounts of precipitation can affect pollutant 

concentrations in the leachate. At landfills (dry disposal sites), rainfall and frozen precipitation 

infiltrates through the waste, dissolving pollutants that can then leach from the landfill. Landfills 

in drier climates will tend to generate less leachate than landfills in wetter climates.

The last factor affecting pollutant concentrations in the leachate is the combustion 

residuals residence time in the surface impoundment or landfill. In a study of metals (calcium, 

copper, iron, lead, magnesium, manganese, potassium, sodium, and zinc) leaching from fly ash 

and bottom ash, all pollutants exhibited a decrease in concentration with time of leaching, except 

for calcium, which released at a constant rate [Kopsick and Angino, 1981]. The most commonly 

noted leachate release curve is an initial flush curve. For this type of curve, the highest 
Section 4—Exposure Pathways 

4-19 

concentrations of metals are released as the leachate initially forms, with rapidly decreasing 

concentrations over time. Therefore, active surface impoundments receiving fresh combustion 

residuals will produce a leachate with elevated concentrations of metals that have a greater 

potential to contaminate drinking water sources and surface waters. Most inactive surface 

impoundments where pollutants have initially already leached from the combustion residuals 

should produce a leachate with decreasing concentrations of metals [Kopsick and Angino, 1981]. 

Thorneloe et al. [2010] studied the 

leaching behavior of coal combustion 

residuals in landfills, performing tests using a 

range of pH conditions and liquid-solid ratios 

expected during management via landfills or 

beneficial use. Leachate concentrations for

most metals were highly variable over a range 

of coal types, plant configurations, and 

combustion residuals types (i.e., fly ash or flue 

gas desulfurization [FGD] gypsum). The study 

showed significantly different leaching results 

(liquid-solid partitioning [equilibrium] as a 

function of pH) for similar combustion 

residuals types and plants. The variability in 

metal leaching results was several orders of 

magnitude higher than the variability of the 

pollutant concentrations in the combustion residuals; this indicates that the pollutant 

concentrations alone cannot predict the leaching of metals, as noted above. Table 4-7 presents

pollutant concentrations in combustion residuals samples across a pH range of 5.4 to 12.4 and 

the range of pollutant concentrations in the leachate. The table also includes indicator values for 

each pollutant: toxicity characteristic (TC) values for Resource Conservation and Recovery Act 

(RCRA) hazardous waste regulatory determination and drinking water MCLs for leachate 

concentrations. As the table shows, the leachate pollutant concentrations for fly ash and FGD 

gypsum exceed both the MCLs and TC values for RCRA hazardous waste determinations for 

nine metals: antimony, arsenic, barium (fly ash only), boron, cadmium, chromium, molybdenum, 

selenium, and thallium.

Transporting Pollutants in the Ground Water

Predicting the transport of combustion residuals pollutants in ground water can be 

challenging due to the wide range of biogeochemical characteristics that can exist between sites 

and within a given site. Pollutant transport times can vary, and combustion residuals pollutants 

can take many years to reach local drinking water wells and surface waters [NRC, 2006]. For 

example, in the damage case at the Virginia Power Yorktown Power Station Chisman Creek 

Dispolar Site in Virginia, fly ash had been disposed of in abandoned sand and gravel pits at the 

site for almost 20 years, from 1957 to 1974. However, ground water contamination was not 

discovered until 1980, when nearby shallow residential wells became contaminated with 

selenium above the primary MCL and vanadium and sulfate above the secondary MCL. After 

further investigation, the ground water around the fly ash disposal areas was found to have 

elevated levels of many types of heavy metals [U.S. EPA, 2007b].

The pH level of pore water in surface impoundments can 

strongly influence the concentration of pollutants in 

leachate from impoundments to ground water.
Section 4—Exposure Pathways 

4-20 

Table 4-7. Range of Fly Ash and FGD Total Content and Leaching Test Results (Initial 

Screening Concentrations) for Trace Metals

Pollutant

Indicator Values

Range of Combustion 

Residuals Content

Range of Leaching Test 

Results

TC Value for 

Hazardous Waste 

Designation

(μg/L)

Drinking 

Water 

MCL 

(μg/L)

Fly Ash 

(mg/kg)

FGD 

Gypsum 

(mg/kg)

Fly Ash 

(μg/L)

FGD 

Gypsum 

(μg/L)

Antimony — 6 3.0 – 14 0.14 – 8.2 <0.3 – 11,000 <0.3 – 330

Arsenic 5,000 10 17 – 510 0.95 – 10 0.32 – 18,000 0.32 – 1,200

Barium 100,000 2,000 50 – 7,000 2.4 – 67 50 – 670,000 30 – 560

Boron — 7,000 a NA NA 210 – 270,000 12 – 270,000

Cadmium 1,000 5 0.3 – 1.8 0.11 – 0.61 <0.1 – 320 <0.2 – 240

Chromium 5,000 100 66 – 210 1.2 – 20 <0.3 – 7,300 <0.3 – 240

Mercury 200 2 0.1 – 1.5 0.01 – 3.1 <0.01 – 0.50 <0.01 – 0.66

Molybdenum — 200 a 6.9 – 77 1.1 – 12 <0.5 – 130,000 0.36 – 1,900

Selenium 1,000 50 1.1 – 210 2.3 – 46 5.7 – 29,000 3.6 – 16,000

Thallium — 2 0.72 – 13 0.24 – 2.3 <0.3 – 790 <0.3 – 1,100

Source: Thorneloe et al., 2010.

Acronyms: MCL (maximum contaminant level); mg/kg (milligrams per kilogram); TC (Toxicity Characteristics); 

μg/L (micrograms per liter); NA (Not Available).

a – The drinking water equivalent level, used for noncarcinogenic endpoints, is listed rather than the MCL. 

Natural mechanisms, such as soil buffering capacity, attenuation of trace metals in certain 

soil types, amount of organic matter, and low soil permeability, can limit the transport of 

combustion residuals pollutants in the subsurface environment. The mobility of metals in the 

subsurface strongly depends on soil-specific characteristics. Soil can exert a buffering influence 

over the leachate by raising or lowering the pH. The solubility of most trace metals (the notable 

exceptions being arsenic and selenium) tend to decrease with increased pH (i.e., alkaline 

conditions). In general, trace metals are less mobile in alkaline soils because the metals will 

precipitate and/or adsorb onto hydrous iron and aluminum oxides. Theis and Richter [1979] 

attempted to assess the factors influencing the attenuation of trace metals in the soil/ground water 

environment. Results show that the major solubility control for cadmium, nickel, and zinc is 

adsorption by iron and manganese oxides while chromium, copper, and lead are controlled by 

precipitation. In some cases, particles in leachate may seal a surface impoundment or landfill, 

reducing the amount of leachate entering the ground water. Simsiman et al. [1987] and Kopsick 

and Angino [1981] both reported evidence of some sealing and reduction in permeability of 

combustion residuals surface impoundments leading to reduced seepage. 

4.2.2 Assessment of the Ground Water Exposure Pathway

The EA focused on the discharges of toxic, bioaccumulative metals to surface waters 

from the evaluated waste streams. The EA did not quantify the environmental and human health 

impacts resulting from pollutants leaching into the ground water from coal combustion residuals 
Section 4—Exposure Pathways 

4-21 

(CCRs) surface impoundments and landfills.36 Additionally, the water quality model used for 

this EA did not consider pollutant loadings to surface waters resulting from the migration of 

CCR pollutants through the soil and into surface waters, even though this may be occurring at 

many of the plants. As shown in Tables A-4 and A-5 in Appendix A, several damage case 

studies have documented impacts to surface waters due to ground water contamination from 

CCR impoundments and landfills. The EA may therefore underestimate the number of 

exceedances occurring at immediate receiving waters (see Section 5).

In 2010, EPA’s Office of Solid Waste and Emergency Response (OSWER) proposed 

regulation of CCRs under RCRA (75 FR 35127 – 35264, June 21, 2010). As part of the final 

CCR rulemaking, OSWER is evaluating ground water contamination associated with combustion 

residuals in surface impoundments and landfills. The ground water impact analysis for the CCR 

rulemaking will identify and quantify human health risks to private drinking water wells due to 

potential ground water contamination from current CCR management practices. EPA will 

include the results of its national-scale analysis of ground water impacts in the documentation for 

the final CCR rulemaking.

4.3 COMBUSTION RESIDUALS SURFACE IMPOUNDMENTS AS ATTRACTIVE NUISANCE

An “attractive nuisance” is an area or habitat that attracts wildlife and is contaminated 

with pollutants at concentrations high enough to potentially harm exposed organisms. Two 

methods of handling combustion wastewater, surface impoundments and constructed wetlands, 

are classified as lentic systems supporting aquatic vegetation and organisms. These methods 

have been known to attract wildlife from other terrestrial habitats and therefore can be 

considered attractive nuisances. As an attractive nuisance, a surface impoundment can impact 

local wildlife as well as transient species that might rely on them during critical reproduction 

periods such as seasonal breeding events [Rowe et al., 2002]. Exposure to combustion 

wastewater during sensitive life cycle events is potentially of concern given that this type of 

exposure has been associated with complete reproductive failure in various vertebrate species 

[Cumbie and Van Horn, 1978; Gillespie and Baumann, 1986; Lemly, 1997; Pruitt, 2000]. 

Organisms that frequent attractive nuisance sites at steam electric power plants, such as 

surface impoundments, risk exposure to elevated metals concentrations. Documented case 

studies have shown that terrestrial fauna nesting near combustion residuals surface 

impoundments can have higher levels of arsenic, cadmium, chromium, lead, mercury, selenium, 

strontium, and vanadium than fauna of the same species at reference sites [Bryan et al., 2003; 

Burger et al., 2002; Hopkins et al., 1997, 1998, 2000, 2002, 2006; Nagle et al., 2001, Rattner et 

al., 2006]. Table A-8 in Appendix A summarizes documented case studies of attractive nuisances 

at steam electric power plants. 

 

36 As part of the benefits and cost analysis, EPA quantified the benefits resulting from improved ground water 

quality under the proposed Steam Electric ELGs. See the Benefits and Cost Analysis for Proposed Steam Electric 

Effluent Limitations Guidelines Regulation (DCN SE03172) for more details.
Section 4—Exposure Pathways 

4-22 

In several of these instances, histopathological effects (i.e., changes in pollutant tissue 

concentrations) were observed. For example, birds nesting near a combustion residuals surface 

impoundment produced eggs with higher selenium concentrations than eggs found at the 

reference site. Although egg selenium concentrations near combustion residuals surface 

impoundments exceeded thresholds that signify adverse effects on reproduction, the study did 

not observe any reduction in reproductive 

success [Bryan et al., 2003]. In a study 

conducted by Hopkins et al. [1998], sediment 

from a contaminated combustion residuals 

surface impoundment had arsenic levels more 

than 100 times higher than the levels found in 

reference site sediments. Adult toads captured 

in the contaminated surface impoundment 

reported a sevenfold difference in arsenic levels 

between those from reference sites [Hopkins et 

al., 1998]. Although the study did not measure 

any indicators of reduced survival or 

reproductive success in the toads, the results 

indicate exposure to combustion residuals 

surface impoundments are a potential threat 

[Hopkins et al., 1998]. 

Multiple studies have linked attractive nuisance areas at steam electric power plants to 

diminished reproductive success. Field studies have documented adverse effects on reproduction 

for turtles and toads living near selenium-laden combustion residuals surface impoundments 

[Hopkins et al., 2006; Nagle et al., 2001]. One laboratory study found that water snakes exposed 

to prey with elevated selenium concentrations reduced their reproductive success [Hopkins et al., 

2002]. In another study, an interior least tern (Sterna antillarum), an endangered migratory bird, 

began nesting at Gibson Lake, an artificial shallow pond that receives combustion residuals pond 

effluent from the Gibson Generating Station in Indiana. Within several years, nearby combustion 

residuals ponds at the Gibson Generating Station were also attracting nesting least terns, placing 

these sensitive species in direct contact with combustion wastewater. To address the attractive 

nuisance problem presented by the ponds, the Gibson Generating Station began a cooperative 

program with the Indiana Department of Natural Resources to protect the nesting birds by 

creating a nearby alternative habitat known as the Cane Ridge Wildlife Management Area 

(WMA) [Pruitt, 2000]. Cane Ridge WMA received water from Gibson Lake and in 2008 the 

U.S. Fish and Wildlife Service became concerned about selenium levels in the water and fish 

present in the Cane Ridge WMA [USFWS, 2008]. Accordingly, the bottom of Cane Ridge was 

plowed to redistribute and bury the selenium in the soil and the flow of water from Gibson Lake 

into Cane Ridge was stopped and replaced with water piped from Wabash River. Duke Energy 

paid to stock the Cane Ridge WMA ponds with fathead minnows to lure back migratory birds. 

As of June 2009, avocets, dunlins, black terns, Forster’s terns, Caspian terns, and 50 endangered 

least terns have returned to Cane Ridge [USFWS, 2012]. 

Other well-documented cases of attractive nuisance settings with similar characteristics 

(e.g., elevated concentrations of specific metals) to those associated with steam electric power 

plants provide further support that combustion residuals surface impoundments have the 

Surface impoundments and constructed wetlands can act 

as attractive nuisances by attracting wildlife and exposing 

them to elevated pollutant levels.
Section 4—Exposure Pathways 

4-23 

potential to pose a threat to wildlife. For example, exposed organisms in attractive nuisance 

settings affected by urban and agricultural wastes have exhibited elevated tissue concentrations 

of metals, with some organisms experiencing a combination of reproductive or sublethal effects 

that adversely impact their survival [Clark, 1987; Hofer et al., 2010; King et al., 1994; Ohlendorf 

et al., 1986, 1988a, 1988b, 1989, 1990; Tsipoura et al., 2008]. Although these case studies do not 

directly relate to steam electric power plants, they highlight the potential dangers of attractive 

nuisances and ability for metals to bioaccumulate in the surrounding wildlife [Ohlendorf et al., 

1986, 1989, 1990]. Table A-9 in Appendix A summarizes documented case studies not specific 

to steam electric power plants.
Section 5—&XUUHQW,PSDFWVIURP6WHDP(OHFWULF,QGXVWU\

5-1 

SECTION 5

CURRENT IMPACTS FROM STEAM ELECTRIC INDUSTRY

As discussed in Section 3, exposure to combustion wastewater has been associated with 

fish kills, reductions in the growth and survival of aquatic organisms, behavioral and 

physiological effects in wildlife and aquatic organisms, and changes to the local habitat [Carlson 

and Adriano, 1993; Rowe et al., 2002]. As well as directly affecting aquatic ecology and local 

wildlife, combustion wastewater has had other environmental impacts such as altering local 

habitats, contaminating drinking water wells, and contributing to fish advisories [U.S. EPA, 

2007b]. This section presents the demonstrated environmental impacts of combustion wastewater 

discharges, including a qualitative discussion of the lethal and sublethal ecological effects of 

pollutants in combustion wastewater, documented instances where combustion wastewater has 

caused fish advisories or exceeded maximum contaminant levels (MCLs) presenting a potential 

human health concern, and the results from the U.S Environmental Protection Agency’s (EPA’s) 

quantitative analysis of the potential environmental impacts to surface water quality, potential 

impacts to ecological receptors (wildlife), and potential impacts to human receptors (human 

health) under current baseline conditions within the industry. 

5.1 ECOLOGICAL IMPACTS

This section provides examples of the lethal and sublethal effects on organisms exposed 

to combustion wastewater metals (e.g., arsenic, cadmium, chromium, copper, mercury, and 

selenium) in surface waters and sediment. Scientific studies reported in the literature included:

• Field studies in which organisms collected from known contaminated sites were 

compared to those collected from uncontaminated sites. 

• Laboratory experiments in which organisms intentionally exposed to combustion 

wastewater were compared to those unexposed. 

Many of the scientific studies documented in the literature focused on selenium as a key 

pollutant of environmental concern within combustion wastewater. However, due to the complex 

nature of the wastewater, many studies evaluated the environmental effects of metals in 

combustion wastewater in aggregate. This section presents the specific lethal and sublethal 

effects attributed to selenium exposure followed by discussions of the lethal and sublethal effects 

of all metals present within combustion wastewater. 

5.1.1 Lethal Effects of Selenium

Predicting the impacts of selenium in aquatic ecosystems can be particularly challenging, 

because selenium can bioaccumulate to toxic levels in organisms inhabiting environments with 

low selenium concentrations. For example, Lemly conducted a field study that investigated the 

patterns of selenium biomagnification and toxicity in aquatic organisms inhabiting a cooling 

water reservoir that received effluent from a power plant’s ash pond [Lemly, 1985a]. Throughout 

the study, selenium concentrations in the reservoir averaged 10 micrograms per liter; however, 

Lemly reported that fish tissue concentrations reached levels ranging from 500 to 4,000 times the 

average reservoir water selenium concentration. The results of the study indicated that the extent 
5-2 

of selenium bioaccumulation depended on the trophic level of the fish present in the reservoir. 

Lemly observed that the selenium accumulation increased as the trophic level increased, which 

potentially correlated with the observed elimination of multiple higher tropic level fish species. 

Therefore, these findings suggest that—even at low concentration within a surface water—

selenium can accumulate and biomagnify to toxic levels in aquatic organisms and pose a lethal 

threat to fish at the top of the trophic structure [Lemly, 1985a]. 

In 1977, two years after the initial operation of the Belews Creek Steam Station in North 

Carolina, the fish community inhabiting the plant’s cooling water reservoir (a lake) underwent 

rapid decline, and species diversity drastically altered [Lemly, 1985a]. Lemly observed that 17 of 

the 20 fish species originally present in the lake were eliminated after the power plant began 

operation, including all game species (temperate perch [Percichthyidae], true perch and pike 

perch [Percidae], and sunfish [Centrarchidae]). Among the 20 initial fish species, Lemly 

reported significant levels of selenium accumulation in the eliminated species and statistically 

unchanged levels of selenium accumulation in the surviving species, relative to levels before the 

power plant began operation. Only three species maintained reproducing populations in the 

reservoir: one native species (mosquitofish) and two introduced non-native species of minnows 

(fathead minnows and red shiners) [Lemly, 1985a]. 

A number of scientific studies expressed concern over selenium exposure within lakes 

and reservoirs where longer residence times allow for further bioaccumulation and a greater 

potential to reach lethal concentrations. In particular, studies concluded that elevated selenium 

concentrations were likely the primary contributor to fish kills in lakes and reservoirs, decreasing 

population density and community diversity [Coughlan and Velte, 1989; Crutchfield, 2000b; 

Crutchfield and Ferguson, 2000a; Cumbie and Van Horn, 1978]. 

5.1.2 Sublethal Effects of Selenium

The sublethal effects of selenium vary widely and can impact growth, reproduction, and 

survival of susceptible organisms. Scientists have demonstrated that various fish and amphibian 

species are sensitive to elevated selenium concentrations such as those found in combustion 

wastewater. These fish and amphibian species have developed sublethal symptoms such as 

accumulation of selenium in tissue (histopathological effects) and in the blood (hematological 

effects), decreased growth, changes in weight, abnormal morphology, and reduced hatching 

success [Coughlan and Velte, 1989; Sager and Colfield, 1984; Sorensen, 1988; Sorensen and 

Bauer, 1984a; Sorensen et al., 1982, 1983, 1984b]. 

The literature indicates that the extent of selenium accumulation in fish tissue varies by 

species, and selenium accumulates most significantly in the liver and reproductive tissues in 

most species [Baumann and Gillespie, 1986; Sager and Colfield, 1984; Sorensen, 1988]. Other 

studies have reported accumulation in the skeletal muscle, kidneys, gills, and hearts of fish, 

resulting in pathological lesions, morphological changes, increased organ weight, and decreased 

growth [Coughlan and Velte, 1989; Sorensen and Bauer, 1984b]. 

In addition, selenium is highly teratogenic (i.e., able to disturb the growth and 

development of an embryo or fetus) and readily transferable from mother to egg. Selenium is 

known to bioaccumulate in the reproductive organs of fish and amphibian species. In one study, 

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ovarian selenium concentrations in bluegill fish were observed at levels 1,000 times greater than 

the surrounding surface water [Baumann and Gillespie, 1986]. Multiple studies have documented 

reproductive failure or other forms of diminished reproductive success in both fish and 

amphibians inhabiting ponds, lakes, and reservoirs contaminated with selenium from combustion 

wastewater discharges [Baumann and Gillespie, 1986; Crutchfield, 2000b; Cumbie and Van 

Horn, 1978; Gillepsie et al., 1986; Hopkins et al., 2002; Nagle et al., 2001]. For example, 

Hopkins et al. [2006] observed reduced hatching success, abnormal swimming, and 

abnormalities in the face and skull in the offspring of selenium-contaminated female toads.

Histopathological effects (i.e., observable changes in tissue), increased metabolic rate, 

and decreased growth rates are effects typically caused by combustion wastewater 

contamination. Water and fish samples collected before and after the discharge of combustion 

wastewater from the ash pond to the Texas Utilities Martin Creek Reservoir found that selenium 

concentrations were significantly elevated in the reservoir and in fish livers, kidneys, and gonads. 

In 1984, Garrett and Inman reported that elevated selenium concentrations persisted in the livers 

and kidneys of several species of fish for up to three years after the combustion wastewater 

discharges ceased. Additionally, a 1988 study by Sorensen found that red ear sunfish native to 

the reservoir exhibited ovary abnormalities related to elevated selenium concentrations up to 

eight years following an eight-month exposure to combustion wastewater discharges. Although 

the ash pond discharge was short-lived, many of the histopathological effects persisted for years 

after the discharge had ceased [Rowe et al., 2002]. 

For a summary of the impacts of selenium on surface water, refer to Table A-10 in 

Appendix A. 

5.1.3 Lethal Effects of Other Metals

Scientific studies have confirmed that both acute and chronic exposure to metals in 

combustion wastewater can be lethal to a wide range of aquatic organisms. For example, Guthrie 

and Cherry [1976] found that shrimp darters and salamanders were highly sensitive to acute 

exposures of combustion wastewater and experienced nearly 100 percent mortality following a 

five-day exposure to combustion wastewater discharges. Invertebrates and fish also evaluated in 

the study were less sensitive to the acute exposure to combustion wastewater and reported lower 

rates of mortality [Guthrie and Cherry, 1976]. Chronic exposures to combustion wastewater are 

also of concern; however, studies show extreme differences in species sensitivity [Rowe et al., 

2002]. For example, juvenile chubsuckers (a benthic fish) exposed for 45 days to sediments, 

water, and food contaminated with combustion wastewater experienced a 75 percent mortality 

rate [Hopkins, 2001]. In another study, bullfrogs exposed to sediment and water from a 

combustion residuals surface impoundment for 34 days demonstrated an 87 percent mortality 

rate (which was 41 percent greater mortality rate than bullfrogs included in control group) [Rowe 

et al., 2002]. A third study reported no lethal effects for banded snakes exposed for two years to 

fish collected from combustion residuals surface impoundments [Hopkins et al., 2002]. 

Other studies examined lethal effects of sediments contaminated with combustion 

residuals. For example, eggs and hatchlings of fish and reptiles raised in contaminated sediment 

reported higher mortality rates (16 to 94 percent) than eggs and hatchlings from control groups 

[Hopkins et al., 2000; Nagle et al., 2001; Roe et al., 2006; Rowe et al., 1998a, 1998b, 2001; 

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Snodgrass et al., 2004]. In each of the studies, elevated mortality rates were observed in 

conjunction with higher concentrations of combustion wastewater metals (e.g., arsenic, 

cadmium, chromium, copper, selenium) in the exposed sediment. 

Three studies evaluated the lethal effects of specific metals in combustion wastewater on 

varying organisms (i.e., insects, fish, and amphibians) and determined the median lethal 

concentration (LC50) for each metal-organism combination. LC50 is the concentration expected to 

be lethal to 50 percent of a group of organisms exposed for a given time duration. Table 5-1

summarizes the results from the three experiments and Table 5-2 presents the LC50

concentrations reported in the studies. Overall, the LC50 studies report species-specific 

differences, particularly among species living downstream of fly ash pond discharges. The 

downstream species developed resistance to metals compared to those living in unpolluted 

ponds. Because the LC50 concentrations were much higher than actual aquatic concentrations, 

there was no evidence in these experiments of acute lethal effects, though long-term (one to three 

months) lethal effects could not be ruled out [Benson and Birge, 1985; Birge, 1978; Specht et al., 

1984]. 

Table 5-1. Summary of Studies Evaluating Lethal Effects of 

 Metals in Combustion Wastewater 

Citation Studied Organism

Test 

Performed

Trace Elements 

Studied Summary of Results

Birge, 

1978

Eggs from goldfish, trout, 

and toads

7- to 28-day 

lethal effects

22 elements Among the 22 elements tested, 

cadmium, chromium, mercury, nickel, 

lead, and silver were the most toxic to 

all three species, with most median 

lethal concentrations (LC50) being 0.1 

milligrams per liter (mg/L) or less.

Benson 

and Birge, 

1985 

Minnows (fish) living in fly 

ash-polluted ponds in 

Kentucky compared to those 

living in uncontaminated 

ponds

Acute (96-

hour) toxicity

Cadmium

Copper

Zinc

The study found a higher tolerance to 

cadmium and copper in the exposed 

fish compared to the fish from 

unpolluted ponds. However, both 

exposed and unexposed populations 

exhibited similar tolerance to zinc. 

Specht et 

al., 1984

Insects (coleopterans, 

mayflies, and other insects) 

exposed to fly ash pond 

effluent from the 

Appalachian Power Plant in 

Giles County, Virginia, 

compared to those living in 

an uncontaminated pond

Acute (96-

hour) toxicity

Cadmium

Copper

Zinc

The study observed a higher tolerance 

to pollutants in exposed insects 

compared to those living in unpolluted 

ponds. 

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Table 5-2. Median Lethal Concentrations (LC50) for Metals in Combustion Wastewater 

Pollutant

LC50, mg/L

7- to 28-Day Exposure 96-Hour Exposure

Trout 

[Birge, 1997]

Goldfish

[Birge, 1997]

Toad 

[Birge, 1997]

Exposed 

Minnows 

[Benson and 

Birge, 1985]

Control 

Minnows 

[Benson and 

Birge, 1985]

Mayflies

[Specht et al., 

1984]

Other Insects 

[Specht et al., 

1984]

Aluminum 0.56 0.15 0.05

Arsenic 0.54 0.49 0.04

Cadmium 0.13 0.17 0.04 3.89 (a)

9.55 (b)

3.06 (a)

7.16 (b)

0.27 1.2 – 250

Chromium 0.18 0.66 0.03

Cobalt 0.47 0.81 0.05

Copper 0.09 5.2 0.04 0.36 (a)

0.41 (b)

0.21 (a)

0.39 (b)

0.18 0.03 – 8.3

Germanium 0.05 5.6 0.05

Lead 0.18 1.66 0.04

Mercury 0.005 0.12 0.001

Nickel 0.05 2.14 0.05

Selenium 4.18 8.78 0.09

Silver 0.01 0.03 0.01

Vanadium 0.16 4.6 0.25

Zinc 1.06 2.54 0.01 6.14 (a)

5.96 (b)

6.09 (a)

7.45 (b)

18.44 18.2

Acronyms: mg/L (milligrams per liter). 

Shaded cells indicate that the pollutant was not evaluated.

a – Nominal water hardness of 100 mg/L calcium carbonate (CaCO3).

b – Nominal water hardness of 250 mg/L calcium carbonate (CaCO3).

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5.1.4 Sublethal Effects of Other Metals

Although the majority of sublethal effects documented in the literature primarily focus on 

selenium concentrations in combustion wastewater, several studies discussed the sublethal 

effects of other pollutants, such as arsenic, cadmium, chromium, copper, and lead [Rowe et al., 

2002]. Sublethal effects from exposure to metals other than selenium in combustion wastewater 

can include changes to morphology (e.g., fin erosion, oral deformities), behavior (e.g., swimming 

ability, ability to catch prey, ability to escape from predators), and metabolism that can 

negatively affect long-term survival. For example, a study of larval bullfrogs living in 

combustion residuals ponds found that more than 95 percent of individuals had abnormal oral 

structures, such as the absence of grazing teeth or entire rows of teeth, which altered feeding 

habits and subsequently reduced growth rates in the affected bullfrogs [Rowe et al., 1996]. In 

another study, tail malformations in larval bullfrogs attributed to combustion wastewater 

exposure caused abnormal swimming behavior and the affected bullfrogs were preyed upon 

more frequently than bullfrogs from unpolluted sites [Raimondo et al., 1998]. 

Several studies have demonstrated increased metabolic rates and decreased growth rates 

in aquatic organisms exposed to combustion wastewater. Increased metabolism causes organisms 

to waste energy during normal metabolic processes, which can affect growth. In a 1998 study by 

Rowe, grass shrimp caged in a combustion residuals pond for eight months experienced a 

51 percent increase in standard metabolic rate. Similarly, crayfish captured near the pond 

experienced increased metabolic rates and decreased growth rates—effects that were also 

observed in crayfish collected from unpolluted sites and exposed to contaminated sediments 

from the combustion residuals pond [Rowe et al., 2002]. 

5.2 POTENTIAL FOR HUMAN HEALTH EFFECTS

Exposure to metals can cause non-cancer effects in humans, including damage to the 

circulatory, respiratory, or digestive systems and neurological and developmental effects. 

Combustion wastewater includes toxic metals and known or suspected carcinogens (e.g., arsenic 

and cadmium). In the literature review, EPA identified potential human impacts from the 

consumption of fish in contaminated waters and from the ingestion of drinking water 

contaminated by combustion wastes. 

During the late 1970s, three power plant cooling water reservoirs in Texas received 

discharges from ash ponds containing elevated selenium levels, resulting in a series of fish kills. 

The reservoirs included Brandy Branch Reservoir, located in Harrison County, Texas; Welsh 

Reservoir, located in Titus County, Texas; and Martin Creek Lake, located in Rusk County, 

Texas. Investigations at the reservoirs implicated elevated selenium levels in the fish tissue as the 

cause. In 1992, the Texas Department of Health issued a fish consumption advisory for the three 

reservoirs after determining that the level of selenium in fish could pose a potential health risk to 

humans, especially children six years or younger and pregnant women. From samples taken in 

1996 and 1997 from Brandy Branch Reservoir, the selenium concentration in 13 largemouth 

bass, one white bass, and three white crappie averaged 0.87 parts per million (ppm) [ATSDR, 

1998a]. From samples taken in 1998 from the Welsh Reservoir, the selenium concentration in 

12 largemouth bass, six channel catfish, one flathead catfish, and one common carp averaged 2.7 

ppm [ATSDR, 1998b]. From samples taken in 1996 and 1997 from Martin Creek Lake, the 

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selenium concentration in 17 largemouth bass, 10 channel catfish, two flathead catfish, four 

black crappie, and one white crappie averaged 2.3 ppm. The national average of selenium 

concentration in fish ranges between 0.1 and 1.5 ppm [ATSDR, 1998c]. 

Ground water and drinking water supplies can be degraded by pollutants in combustion 

wastewater and residuals via leachate [Cross, 1981]. Leachate can migrate from the site in the 

ground water at concentrations that could contaminate public or private drinking water wells and 

surface waters, even years following disposal of combustion residuals [NRC, 2006]. For 

example, in the damage case at the Wisconsin Electric Power Company (WEPCO) facility in 

Port Washington, Wisconsin, fly ash had been disposed of in a quarry for over 20 years (1943-

1971) before selenium and boron contamination was reported in a private drinking water well at 

a depth of 40-60 feet located 250 feet downgradient from the coal-fired power plant waste 

disposal site [U.S. EPA, 2007b]. 

As discussed in Section 3 and Appendix A, there have been documented exceedances of 

MCL drinking water standards at off-site ground water and drinking water wells. The most 

common pollutants that exceeded their MCL were arsenic, selenium, boron, and manganese 

(secondary standard) for both combustion residuals surface impoundments and landfills. In 

addition, exceedances of cadmium and lead 

from surface impoundments and sulfates from 

landfills were also observed [EIP et al., 2010a 

and 2010b; MDNRE, 2010; U.S. EPA, 2007b]. 

Exceedances of MCLs in the ground water 

indicate potential human health impacts if the 

pollutants enter private drinking water wells. 

Section 3.5.2 outlines three case studies where 

leachate contamination caused impacts to 

private drinking water wells. 

Exceedances of drinking water 

standards can also occur in surface waters. For 

example, Duke Energy's Riverbend Plant 

discharges ash pond effluent into Mountain 

Island Lake, which supplies drinking water to 

700,000 people. The county detected arsenic and zinc concentrations above state standards in an 

area near the ash pond discharge pipe [Charlotte Observer, 2010]. As discussed in Section 3.4.4, 

most of the pollutants in the surface water and ground water would likely be reduced to safe 

levels during drinking water treatment. However, these pollutants could potentially impact the 

effectiveness of the treatment processes. Approximately 85 percent of steam electric plants are 

located near public wells and 37 percent are located near a drinking water intake for surface 

water.

5.3 QUANTIFIED ENVIRONMENTAL IMPACTS

EPA developed the receiving water model described in Section 4.1.2 to quantify the 

current environmental impacts of direct surface water discharges of the evaluated waste streams 

(i.e., flue gas desulfurization (FGD) wastewater, fly ash transport water, bottom ash transport 

Various case studies document exceedances of drinking 

water standards at ground water and drinking water wells 

due to leachate from nearby impoundments and landfills.

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5-8 

water, and leachate) from steam electric power plants. This section presents the baseline results 

of the modeled pollutant concentrations in surface waters and fish tissue and their potential 

impacts to aquatic life, wildlife, and human health.

5.3.1 Water Quality Impacts 

The quality of a surface water is defined by its chemical, physical, and biological 

characteristics and is measured to evaluate a water’s potential to harm aquatic life and human 

health. EPA assessed the quality of surface waters that receive discharges of the evaluated waste 

streams by comparing estimated pollutant concentrations in the water column based solely on 

steam electric industry discharges to the National Recommended Water Quality Criteria 

(NRWQC) and drinking water MCLs. Based on the modeling results for surface water quality 

impacts, EPA determined that approximately 67 percent of the lakes, ponds, and reservoirs 

(24 out of 36) and 47 percent of the rivers and streams (123 out of 261) that receive discharges of 

evaluated waste streams are experiencing a quantifiable reduction in water quality due to those 

discharges.

Based on the modeling results, human health criteria exceedances are more prevalent 

among the immediate receiving waters than aquatic life criteria exceedances. Approximately 20 

to 49 percent of the immediate receiving waters had modeled water concentrations that exceed a 

human health criterion, while approximately 10 to 23 percent of the immediate receiving waters 

had modeled water concentrations that exceed an aquatic life criterion. The difference between 

exceedances for human health and aquatic life criteria is due to the significantly lower human 

health criteria, when compared to aquatic life criteria. 

Table 5-3 presents the number and percentage of immediate receiving waters with 

estimated water concentrations that exceed each water quality criterion. These exceedances are 

based solely on discharges from steam electric power plants. For the model, EPA did not include 

any additional sources of pollutants (e.g., naturally-occurring metals, non-point source 

discharges, or other point source discharges). 

The reduced water quality presented in Table 5-3 is primarily attributed to total arsenic, 

total thallium, dissolved cadmium, and total selenium concentrations in the water column. For 

human health, estimated water concentrations exceeded criteria primarily for arsenic, thallium, 

and cadmium. For instance, 147 out of the 297 immediate receiving waters exceed the human 

health NRWQC for the consumption of arsenic-contaminated water and organisms (0.018 

micrograms per liter [μg/L]); 96 exceed the NRWQC for consumption of organisms only (0.14 

μg/L) ; and 19 exceed the MCL (10 μg/L). Therefore, humans consuming water and/or 

organisms inhabiting these waters are more at risk to skin damage, cardiovascular disease, and 

cancer in the skin, lungs, bladder, and kidney. In comparison, aquatic organisms are at risk for 

exposure to cadmium and selenium. This is because, for example, estimated water concentrations 

in more than 13 percent of the immediate receiving waters (40 out of 297) exceed the aquatic life 

criterion for chronic exposure to cadmium- and selenium-contaminated waters (0.25 and 5 μg/L, 

respectively). Therefore, aquatic organisms inhabiting these waters are under a greater threat for 

cadmium-related effects (tissue damage and organ abnormalities) and selenium-related effects 

(reduced growth, increased metabolic rates, reproductive failure, and death). Sublethal and lethal 

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impacts from chronic selenium exposure are frequently cited in literature. For more information 

on these impacts, refer to Section 5.1. 

Table 5-3. Number and Percentage of Immediate Receiving Waters with Estimated 

Water Concentrations that Exceed the Water Quality Criteria

Evaluation Criterion

Number of Immediate Receiving Waters Exceeding a Criterion a

Number of

Rivers and 

Streams

Number of

Lakes, Ponds, 

and 

Reservoirs

Total Immediate Receiving 

Waters b

Number 

Exceeding

Percentage

Exceeding

Aquatic 

Life

Criteria

Freshwater Acute NRWQC 27 4 31 10%

Freshwater Chronic NRWQC 53 14 67 23%

Human 

Health

Criteria

Human Health Water and 

Organism NRWQC 123 24 147 49%

Human Health Organism Only 

NRWQC 84 15 99 33%

Drinking Water MCL 47 12 59 20%

Total Number of Unique Immediate 

Receiving Waters c 123 24 147 49%

Acronyms: NRWQC (National Recommended Water Quality Criteria); MCL (Maximum Contaminant Level). 

a – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the water quality model [ERG, 2013h]. 

b – These values are the sum and percentage of rivers, streams, lakes, ponds, and reservoirs impacted.

c – This represents the number of unique immediate receiving waters that exceeded at least one criterion.

Table F-1 in Appendix F presents additional details on the number and percentage of 

immediate receiving waters that are exceeding each water quality criterion by pollutant. For 

more detailed information on the modeled immediate receiving water concentrations under 

baseline conditions see Figures F-1 to F-10 and Tables F-2 to F-11 in Appendix F. 

5.3.2 Wildlife Impacts

As part of the wildlife impacts analysis, EPA assessed the impacts of the evaluated waste 

streams on the following categories:

• Impacts to aquatic life due to changes in water quality;

• Impacts to wildlife from contact with contaminated sediment; and

• Impacts to wildlife from consumption of contaminated fish. 

Bioaccumulative metals in surface waters from steam electric discharges are known to 

accumulate through the food chain and affect local wildlife populations. Selenium is of particular 

concern in aquatic environments because it can accumulate in sediment and biomagnify to toxic 

levels in fish inhabiting selenium-contaminated waters (even at relatively low selenium 

concentrations), potentially eliminating piscivorous (fish-eating) wildlife higher in the food chain 

[Ohlendorf et al., 1988a]. Impacts to fish populations are well documented in the literature for 

selected case studies [Garrett and Inman, 1984; Lemly, 1985a; Sorensen et al., 1982]. To expand 

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beyond the case study sites and assess the broader impacts steam electric discharges pose to local 

fish populations, EPA modeled selenium concentrations in fish tissue and compared these 

concentrations to concentrations documented in the literature as causing reduced reproductive 

success and histopathological effects in fish. Table 5-4 presents the number and percentage of 

immediate receiving waters with estimated selenium fish tissue concentrations that exceed the 

documented impact selenium concentrations in trophic level 3 (T3) and trophic level 4 (T4) fish. 

According to the modeling results, estimated fish tissue concentrations of selenium in 

approximately 12 to 18 percent of the waters receiving discharges that were evaluated exceeded 

levels with known impacts to fish, with the precise number of exceedances depending on the 

trophic level of the fish. Although these fish populations may not be experiencing lethal impacts, 

the sublethal damage to their reproductive systems may eventually impact the overall success of 

the fish populations near steam electric power plants. As was observed in the Belews Lake case 

study, this is especially an issue in lakes, ponds, and reservoirs, where healthy fish populations 

cannot migrate and seek out alternative food sources. Decreased fish populations may alter the 

structure of these aquatic communities and cause cascading effects within the food web that can 

impact the success of other organisms in the ecosystem.

For more information on the potential environmental impacts from selenium exposure, 

refer to the selenium discussions in Sections 3.1 and 5.1. For more detailed information on 

baseline modeled fish tissue concentrations in the immediate receiving water for selenium and 

other metals evaluated in the EA see Figures F-11 to F-21 and Tables F-12 to F-22 in 

Appendix F. 

Table 5-4. Comparison of Modeled Selenium Concentrations in Fish Tissue to Documented 

Concentrations of Selenium in Fish Tissue Known to Cause Adverse Effects 

Wildlife 

Affected

Trophic 

Level

Documented 

Impact Selenium 

Concentration 

(μg/g) b

Number of Immediate Receiving Waters Exceeding 

Documented Concentrations a

Number of

Rivers and 

Streams

Number of

Lakes, 

Ponds, and 

Reservoirs

Total Receiving Waters c

Number 

Exceeding

Percentage 

Exceeding

Largemouth 

bass 

(Micropterus 

salmoides)

T4

Female carcass = 

2.86 44 9 53 18%

Male carcass = 

2.63 45 9 54 18%

Bluegill 

(Lepomis 

macrochirus)

T3

Female carcass = 

2.74 33 7 40 13%

Male carcass = 

4.64 29 7 36 12%

Acronyms: μg/g (micrograms per gram).

a – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the wildlife model (ERG, 2013i; ERG, 2013j). 

b –Baumann and Gillespie [1986] concluded that the documented selenium concentrations that accumulated in the 

fish carcasses resulted in negative reproductive and histopathological effects.

c – These values are the sum and percentage of rivers, streams, lakes, ponds, and reservoirs impacted.

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EPA also assessed the potential impact to wildlife exposed to sediments in surface waters 

that receive discharges of the evaluated waste streams by comparing estimated pollutant 

concentrations in the sediment to EPA’s Assessment and Remediation of Contaminated 

Sediments (ARCS) Program Guidelines.

37 As discussed in Section 4.1.2, the wildlife model 

expresses the potential impact to wildlife in terms of a hazard quotient (HQ). An HQ is the ratio 

of concentration in contaminated media to a concentration benchmark. An HQ greater than 1 

indicates a potential impact to wildlife for the endpoint associated with the benchmark value. 

EPA calculated that only 1 percent of rivers and streams (3 out of 261) considered in this 

assessment and zero percent of lakes, ponds, and reservoirs had estimated sediment pollutant 

concentrations that may be toxic to wildlife. These results may underrepresent the impact to 

wildlife from sediment contamination, primarily due to certain assumptions and limitations of 

the model. Specifically, the immediate receiving water model evaluates only a snap shot in time 

following exposure to average annual loadings. The modeling does not take into account 

accumulation of pollutants in sediments over time either in the lake or river environment. It is 

likely that cumulative accumulations over multiple years of loadings would result in sediment 

concentrations considerably higher than the modeling results predict. As support for this 

interpretation, several publications in the literature confirm that sediment exposure impacts are 

more likely to occur in lake environments where pollutants can accumulate in sediments over 

time [Hopkins et al., 2000, 2003; Lemly, 1997]. 

In addition to direct impacts on fish and other aquatic life, EPA identified numerous 

literature articles documenting impacts from bioaccumulative metals on the surrounding wildlife. 

To quantify the potential impacts of the evaluated waste streams on the surrounding wildlife, 

EPA selected minks and eagles as indicator species to assess the threat to piscivorous species in 

the areas of concern. Eagles and minks are distributed across much of the United States and a 

majority of their diets are composed of fish, making them appropriate indicator species for a 

national assessment of bioaccumulation through the foodweb from consumption of fish. 

EPA assessed the potential impact to piscivorous wildlife from the evaluated waste 

streams by modeling fish tissue metal concentrations and comparing these concentrations to no 

effect hazard concentrations (NEHC) for minks and eagles developed by the U.S. Geological 

Survey (USGS). Based on the estimated fish tissue concentrations, EPA determined that 

approximately 43 percent of the immediate receiving waters (129 out of 297) pose a threat to 

eagles and 33 percent of the immediate receiving waters (99 out of 297) pose a threat to minks 

through the consumption of contaminated fish. This result demonstrates that estimated pollutant 

concentrations in fish that inhabit receiving waters immediately downstream from combustion 

wastewater discharges pose a reproductive threat to surrounding minks and eagles and is an 

indication of the potential broader impacts combustion wastewater discharges may pose to the 

greater environment as metals transfer from the aquatic environment and begin to accumulate in 

terrestrial food webs. 

As expected, modeling results indicated that pollutant concentrations in fish inhabiting 

lakes, ponds, and reservoirs are more likely to exceed adverse effect benchmarks for wildlife that 

consume fish compared to pollutant concentrations in fish inhabiting rivers and streams. EPA 

 

37 The ARCS benchmarks did not include mercury. EPA used an alternative benchmark as listed in Table D-1 in 

Appendix D. 

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determined that the estimated fish tissue concentrations would pose a threat to minks and eagles 

in approximately 78 percent of lakes, ponds, and reservoirs (28 out of 36) that were evaluated 

and in 39 percent of rivers and streams (101 out of 261) that were evaluated. These results are 

expected, since fish populations inhabiting lake environments cannot travel to uncontaminated 

waters and, therefore, continue to bioaccumulate pollutants. 

Table 5-5 presents the number and percentage of immediate receiving waters that exceed 

the USGS wildlife fish consumption NEHC for minks and eagles. 

Table 5-5. Number and Percentage of Immediate Receiving Waters That Exceed Wildlife 

Fish Consumption NEHC for Mink and Eagle

Evaluation Criterion

Number of Immediate Receiving Waters with HQ >1 a

Number of Rivers 

and Streams

Number of Lakes, 

Ponds, and 

Reservoirs

Total Receiving Waters b

Number 

Exceeding

Percentage 

Exceeding

Mink fish consumption 

NEHC 77 22 99 33%

Eagle fish consumption 

NEHC 101 28 129 43%

Total Number of Unique 

Immediate Receiving 

Waters c

101 28 129 43%

Acronyms: HQ (Hazard Quotient); NEHC (No Effect Hazard Concentration). 

a – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the wildlife model [ERG, 2013i]. 

b – These values are the sum and percentage of rivers, streams, lakes, ponds, and reservoirs impacted.

c – This represents the number of unique immediate receiving waters that exceed a criterion.

The pollutants found to present the greatest threat to minks and eagles from fish 

consumption were mercury and selenium. Approximately 32 to 43 percent of the immediate 

receiving waters contained fish with modeled mercury concentrations exceeding the NEHC 

benchmark for mink or eagle fish consumption, and approximately 15 to 16 percent of the 

immediate receiving waters contained fish with modeled selenium concentrations exceeding a 

fish consumption NEHC benchmark for mink or eagle. 

Table 5-6 presents the number and percentage of immediate receiving waters that exceed 

a USGS wildlife fish consumption NEHC for minks and eagles by pollutant. 

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Table 5-6. Number and Percentage of Immediate Receiving Waters That Exceed Wildlife 

Fish Consumption Hazard Quotients for Mink and Eagle by Pollutant

Pollutant

Mink Eagle

Fish 

Consumption 

NEHC a

Immediate Receiving 

Waters with HQ >1 Fish 

Consumption 

NEHC a

Immediate Receiving Waters 

with HQ >1

Number 

Exceeding b

Percentage 

Exceeding

Number 

Exceeding b

Percentage 

Exceeding

Arsenic 7.65 2 <1% 22.4 0 0%

Cadmium 5.66 12 4% 14.7 9 3%

Chromium VI 17.7 c 0 0% 26.6 c 0 0%

Copper 41.2 0 0% 40.5 0 0%

Lead 34.6 1 <1% 16.3 3 1%

Mercury 0.37 96 32% 0.5 127 43%

Nickel 12.5 0 0% 67.1 0 0%

Selenium 1.13 48 16% 4 46 15%

Thallium ID NC NC ID NC NC

Zinc 904 2 <1% 145 11 4%

Acronyms: HQ (Hazard Quotient); ID (Insufficient Data; no benchmarks were identified in the wildlife HQ analysis 

for thallium); NC (Not Calculated); NEHC (No Effect Hazard Concentration). 

a – The wildlife fish consumption NEHC represents the maximum pollutant concentration in the fish will result in 

no observable adverse effects in wildlife (i.e., minks or eagles) [USGS, 2008].

b – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the wildlife model [ERG, 2013i]. 

c – An NEHC benchmark is not available for chromium VI; therefore, EPA used the total chromium benchmark.

5.3.3 Human Health Impacts

In addition to the assessment of water quality impacts on human health discussed in 

Section 5.3.1, EPA expanded the analysis to evaluate human health impacts from consumption of 

fish in immediate receiving waters downstream from discharges of the evaluated waste streams. 

The purpose of this analysis is to evaluate the broader bioaccumulative effects of metals in steam 

electric discharges and account for the potential for average daily doses of pollutants from fish 

consumption to exceed human health thresholds where water concentrations may not indicate an 

issue. EPA evaluated multiple human cohorts (i.e., recreational and subsistence fishers, children 

and adults) by calculating the average daily dose of metals from fish consumption using the 

estimated fish tissue concentrations calculated in the model. EPA varied the fish consumption 

rate and body weight of each cohort (based on age) to determine the average and long-term daily 

doses for each pollutant. EPA calculated the lifetime excess cancer risk (LECR) based on 

estimated fish tissue concentrations of inorganic arsenic and calculated non-cancer threats by 

comparing the average daily doses to threshold values for all metals with published reference 

doses. For more information on how EPA identified potential impacts to human receptors, see 

Section 4.1.2. 

Table 5-7 presents the number and percentage of immediate receiving waters where the 

estimated LECR for the human receptor exceeded the selected threshold, 1-in-1,000,000 cancer 

risk for arsenic. EPA determined that arsenic concentrations in fish resulted in an estimated 

cancer risk greater than 1-in-1,000,000 to adult subsistence fishers in approximately 9 percent of 

Section 5—&XUUHQW,PSDFWVIURP6WHDP(OHFWULF,QGXVWU\
5-14 

the immediate receiving waters (27 out of 297). Cancer risks for the remaining cohorts were 

much lower, with LECRs exceeding the cancer risk threshold in 1 to 4 percent of the immediate

receiving waters. The human health model presents the risk results for each age group 

individually to allow for further manipulation in the benefits analysis. The true cancer risk to a 

child would depend on the amount of time the child consumed fish from locations downstream 

from steam electric discharges. For example, the cancer risk for a 6-year-old child who was born 

and raised in the same place would be the sum of the LECRs from the 1 to <2 years, 2 to <3 

years, and 3 to <6 years cohort groups. 

Table 5-7. Number and Percentage of Immediate Receiving Waters That Exceed Human 

Health Evaluation Criteria (Lifetime Excess Cancer Risk) for Inorganic Arsenic

Receptor Cohort

Exposure 

Duration

(Years)

Number of Immediate Receiving Waters Where

Lifetime Excess Cancer Risk Exceeds 1-in-a-Million a, b

Number of

Rivers and 

Streams

Number of

Lakes, Ponds, 

and Reservoirs

Total Receiving Waters c

Number 

Exceeding

Percentage 

Exceeding

Child 

recreational 

fisher

1 to <2 years 1 2 0 2 1%

2 to <3 years 1 2 0 2 1%

3 to <6 years 3 3 0 3 1%

6 to <11 years 5 5 0 5 2%

11 to <16 years 5 3 0 3 1%

16 to <21 years 5 3 0 3 1%

Adult recreational fisher 49 12 0 12 4%

Child 

subsistence 

fisher

1 to <2 years 1 7 0 7 2%

2 to <3 years 1 7 0 7 2%

3 to <6 years 3 9 0 9 3%

6 to <11 years 5 9 0 9 3%

11 to <16 years 5 9 0 9 3%

16 to <21 years 5 9 0 9 3%

Adult subsistence fisher 49 25 2 27 9%

a – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the human health model [ERG, 2013i]. 

b – Inorganic arsenic cancer slope factor of 1.5 per milligram per kilogram per day.

c – These values are the sum and percentage of rivers, streams, lakes, ponds, and reservoirs impacted.

A limitation of the modeling that may result in an underestimate of the cancer risk is the 

fact that the risks are based on an exposure to an average annual loadings; the model does not 

consider the potential for pollutants to accumulate over time in the environment. The model 

estimates a minimal cancer risk from consuming fish in lakes, ponds, and reservoirs that receive 

discharges of the evaluated waste streams. The cancer risk is likely greater in a lake 

environment, where fish are limited in their food sources and can accumulate pollutants over a 

longer exposure period than is represented in the model. Even given the limitations of the 

modeling framework, EPA determined that the inorganic arsenic concentrations in fish in 

6 percent of the lakes pose a cancer risk to adult subsistence fishers. 

Based on the estimated fish tissue concentrations and pollutant average daily doses by 

cohort, EPA determined that subsistence fishers (adults and children) would have the greatest 

Section 5—&XUUHQW,PSDFWVIURP6WHDP(OHFWULF,QGXVWU\
5-15 

threat for non-cancer health effects. This was because the average daily doses (for one or more 

pollutant) exceeded the oral reference dose values in 57 to 66 percent of the immediate receiving 

waters, depending on the age group evaluated. Recreational fishers (adult or child) have less of a 

threat, with average daily doses exceeding oral reference doses in 36 to 43 percent of the 

immediate receiving waters. These results suggest that fish downstream from discharges of the 

evaluated waste streams pose a non-cancer health threat to surrounding fisher populations. Given 

the limitations of the model described above, these results may underestimate the non-cancer 

health impacts posed by fish in the lake environment. 

Table 5-8 presents the number and percentage of immediate receiving waters where one 

more pollutant average daily dose exceeds an oral reference dose for non-carcinogens.

Table 5-8. Number and Percentage of Immediate Receiving Waters 

That Exceed Non-Cancer Oral Reference Dose Values

Receptor Cohort

Exposure 

Duration

(Years)

Number of Immediate Receiving Waters Where Estimated 

Exposure Doses Exceed Non-Cancer Reference Doses a

Number of 

Rivers and 

Streams

Number of

Lakes, Ponds, 

and Reservoirs

Total Receiving Waters b

Number 

Exceeding

Percentage 

Exceeding

Child 

recreational 

fisher

1 to <2 years 1 97 27 124 42%

2 to <3 years 1 97 27 124 42%

3 to <6 years 3 93 27 120 40%

6 to <11 years 5 90 26 116 39%

11 to <16 years 5 85 23 108 36%

16 to <21 years 5 85 23 108 36%

Adult recreational fisher 49 100 28 128 43%

Child 

subsistence 

fisher

1 to <2 years 1 161 32 193 65%

2 to <3 years 1 161 32 193 65%

3 to <6 years 3 164 32 196 66%

6 to <11 years 5 158 31 189 64%

11 to <16 years 5 137 31 168 57%

16 to <21 years 5 137 31 168 57%

Adult subsistence fisher 49 158 31 189 64%

Acronym: HQ (Hazard Quotient). 

a – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the human health model [ERG, 2013i]. 

b – These values are the sum and percentage of rivers, streams, lakes, ponds, and reservoirs impacted.

According to the exposure doses calculated from the estimated fish tissue concentrations, 

methylmercury poses the greatest threat to cause non-cancer health effects in humans from fish 

consumption. EPA determined that fish mercury concentrations pose a non-cancer threat to 

humans in approximately 65 percent of the immediate receiving waters. Therefore, humans who 

consume mercury-contaminated fish inhabiting these waters would be at risk for developing 

mercury-related effects, which could include neurological symptoms (e.g., affecting fine motor 

function, language skills, verbal memory) and cardiovascular disease if at exposed at high 

enough doses. In addition, EPA determined that fish thallium concentrations pose a non-cancer 

Section 5—&XUUHQW,PSDFWVIURP6WHDP(OHFWULF,QGXVWU\
5-16 

threat to humans in approximately 40 percent of immediate receiving waters.

38 Therefore, 

humans who consume thallium-contaminated fish inhabiting these waters are more likely to 

develop neurological symptoms (e.g., weakness, sleep disorders, muscular problems), alopecia 

(i.e., loss of hair from the head and body), and gastrointestinal effects (e.g., diarrhea and 

vomiting).

Table 5-9 presents the number and percentage of immediate receiving waters where 

average daily doses exceed an oral reference dose for non-carcinogens by pollutant. 

Table 5-9. Number and Percentage of Immediate Receiving Waters That Exceed NonCancer Oral Reference Dose Values by Pollutant

Pollutant

Oral

Reference Dose

(mg/kg/d)

Number of Immediate Receiving Waters Where HQ>1 

for Non-Cancer Reference Doses

Number Exceeding a Percentage Exceeding

Inorganic arsenic 0.0003 (b) 3 1%

Cadmium 0.001 (b) 28 9%

Chromium VI 0.003 (b) 0 0%

Copper (c) 0 0%

Lead ID NC NC

Mercury (as methylmercury) 0.0001 (b) 193 65%

Nickel (soluble salts) 0.02 (b) 0 0%

Selenium 0.005 (b) 45 15%

Thallium (soluble salts) 0.00001 (d) 118 40%

Zinc 0.3 (b) 10 3%

Acronyms: NC (Not Calculated); ID (Insufficient Data; there is no current reference dose for lead).

a – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the human health model [ERG, 2013i].

b – U.S. EPA, 2011c.

c – ATSDR, 2010a.

d – U.S. EPA, 2010a. 

States, territories, and authorized tribes have the primary responsibility to protect 

residents from the health risks of consuming contaminated non-commercially caught fish. They 

inform the general population, including recreational and subsistence fishers, typically by issuing 

advisories that notify the public that chemical contamination found in local fish may present a 

public health hazard. 

EPA modeled concentrations in T4 fish tissue and compared them to fish consumption 

advisory screening values to assess the potential for discharges of the evaluated waste streams to 

cause or contribute to fish advisories and pose a human health hazard. Based on the modeling 

analysis, EPA determined that up to 73 percent of the immediate receiving waters included in the 

analysis would contain fish with contamination levels that would likely trigger advisories for 

recreational and subsistence fishers. Mercury and selenium were the pollutants most likely to 

 

38 EPA used the chronic oral exposure value cited in U.S. EPA, 2010a for thallium chloride as the reference dose.

Section 5—&XUUHQW,PSDFWVIURP6WHDP(OHFWULF,QGXVWU\
5-17 

trigger a fish advisory. This result indicates that steam electric power plants are contributing to 

the already widespread concentrations of mercury and selenium in fish throughout the country. 

Table 5-10 presents the number and percentage of immediate receiving waters where the 

modeled T4 fish tissue concentrations exceed screening values used for fish advisories. 

Table 5-10. Comparison of T4 Fish Tissue Concentrations to 

Fish Advisory Screening Values 

Pollutant

Recreational Fishers Subsistence Fishers

Screening 

Value

(ppm) a

Number 

Exceeding b

Percentage 

Exceeding

Screening 

Value

(ppm) a

Number 

Exceeding b

Percentage 

Exceeding

Inorganic arsenic 

(noncarcinogen) 1.2 0 0% 0.147 3 1%

Inorganic arsenic 

(carcinogen) 0.026 7 2% 0.00327 14 5%

Cadmium 4.0 13 4% 0.491 30 10%

Mercury (as 

methylmercury) 0.4 133 45% 0.049 216 73%

Selenium 20 33 11% 2.457 54 18%

a – Screening values are defined as concentrations of target analytes in fish or shellfish tissue that are of potential 

public health concern and that are used as threshold values against which levels of contamination in similar tissue 

collected from the ambient environment can be compared. Exceedance of these screening values should be taken as 

an indication that more intensive site-specific monitoring and/or evaluation of human health risk should be 

conducted [U.S. EPA, 2000a, Table 5-3]. 

b – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were 

included in the human health model [ERG, 2013i]. 

Section 5—&XUUHQW,PSDFWVIURP6WHDP(OHFWULF,QGXVWU\
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-1 

SECTION 6 

ENVIRONMENTAL IMPROVEMENTS

UNDER THE PROPOSED REGULATORY OPTIONS

In Section 5, the U.S. Environmental Protection Agency (EPA) presented the 

environmental impacts to surface water quality, wildlife, and human health estimated with EPA’s 

receiving water model resulting from current (baseline) combustion wastewater discharges. 

Under the proposed Steam Electric effluent limitation guidelines and standards (ELGs), EPA 

evaluated eight regulatory options (Table 6-1). As part of this quantitative EA, EPA evaluated 

the environmental improvements associated with the reduction in pollutant loadings from the 

evaluated waste streams—i.e., flue gas desulfurization (FGD) wastewater, fly ash transport 

water, bottom ash transport water, and leachate—under each option.39 Section 8 of the Technical 

Development Document for the Proposed Effluent Limitations Guidelines and Standards for the 

Steam Electric Power Generating Point Source Category (TDD) (DCN SE01964) details the 

technology options for all waste streams evaluated under each regulatory option considered in 

support of the proposed ELGs. As described in Section 8 of the TDD, EPA is proposing four 

preferred alternatives for the new Best Available Technology Economically Achievable (BAT) 

limitations and Pretreatment Standards for Existing Sources (PSES requirements (i.e., 

Regulatory Options 3a, 3b, 3, and 4a) under the proposed ELGs. EPA is proposing Regulatory 

Option 4 for the new NSPS and PSNS requirements. See Section 12 of the TDD for further 

information on the limitations and standards of the preferred options. This section presents the 

improvements to surface water quality, wildlife, and human health estimated in EPA’s receiving 

water model projected to result from the proposed ELGs. 

Based on the quantitative and qualitative analyses performed for the EA, EPA estimated a 

variety of environmental improvements to result from the reductions in pollutant loadings 

associated with the regulatory options. In particular, the EA evaluated 1) improvements in water 

quality, 2) reduction in threats to wildlife, 3) reduction in human health cancer risks, 4) reduction 

in threats for non-cancer human health effects, and 5) other unquantified environmental 

improvements. Table 6-2 lists the quantified and unquantified environmental improvements 

estimated to result from the preferred options under the proposed Steam Electric ELGs and 

designates which quantified improvements were monetized in the benefits analysis described in 

the Benefits and Cost Analysis for Proposed Steam Electric Effluent Limitations Guidelines 

Regulation (DCN SE03172) (Benefits and Cost Analysis).

For five of the regulatory options (Options 1, 2, 3, 4, and 5), EPA modeled improvements 

using the receiving water model, as described in Appendices C (Water Quality Model 

Methodology), D (Wildlife Model Methodology), and E (Human Health Model Methodology). 

 

39 In addition to the waste streams listed in Table 6-1, EPA evaluated technology options associated with FGMC 

wastewater, gasification wastewater, and nonchemical metal cleaning wastes as part of the regulatory options. 

However, no plants currently discharge FGMC wastewater; all existing gasification plants are operating the 

technology used as the basis for the regulatory option; and the proposed limitations and standards for nonchemical 

metal cleaning wastes are equal to current BPT limitations for existing direct dischargers. Therefore, EPA estimated 

zero compliance costs and zero pollutant reductions associated with these waste streams and did not include these 

two waste streams in the EA.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-2 

EPA then applied adjustment factors to this modeled output to estimate improvements for 

Options 3a, 3b, and 4a, as described in Appendix G (Methodology for Non-Modeled Options). 
6-3

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-1. Regulatory Options Evaluated in the EA 

Waste 

Stream

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

FGD 

wastewater

Chemical 

precipitation

Chemical 

precipitation 

+ biological 

treatment

Best Professional 

Judgment (BPJ) 

determination

Chemical 

precipitation + 

biological treatment 

for units at a facility 

with a total wetscrubbed capacity 

of 2,000 MW and 

more; BPJ 

determination for 

<2,000 MW

Chemical 

precipitation + 

biological 

treatment

Chemical 

precipitation + 

biological 

treatment

Chemical 

precipitation + 

biological 

treatment

Chemical 

precipitation + 

evaporation

Fly ash 

transport 

water

Impoundment Impoundment Dry handling Dry handling Dry handling Dry handling Dry handling Dry handling

Bottom ash 

transport 

water

Impoundment Impoundment Impoundment Impoundment Impoundment Dry handling/

closed loop

(for units >400 

MW); 

impoundment for 

units ≤400 MW

Dry handling/

closed loop

Dry handling/

closed loop

Leachate Impoundment Impoundment Impoundment Impoundment Impoundment Impoundment Chemical 

precipitation

Chemical 

precipitation

Acronym: MW (megawatt). 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-4 

Table 6-2. Description of Environmental Improvements 

from Preferred Regulatory Options 

Assessment 

Category

Description of Environmental 

Improvement

Improvement 

Quantified

Improvement 

Monetized More Information

Water 

Quality

Reduction in number of immediate 

receiving waters exceeding an acute 

or chronic aquatic life NRWQC



Section 6.2 and 

Section 6.3

Reduction in number of immediate 

receiving waters exceeding a human 

health NRWQC



Section 6.2 and 

Section 6.3

Reduction in number of immediate 

receiving waters exceeding MCLs

 Section 6.2 and 

Section 6.3

Increased aesthetics from improved 

water clarity, color, odor, including 

nearby site amenities (residing, 

working, traveling)

 

Benefits and Cost 

Analysis a

Improved swimming, fishing, 

boating, and near-water activities 

from improved water quality

 

Benefits and Cost 

Analysis a 

Improved quality of source water 

used for drinking , irrigation, and 

industrial use 

Qualitative 

Discussion (Benefits 

and Cost Analysis) 

Increased property values from water 

quality improvements

Qualitative 

Discussion (Benefits 

and Cost Analysis) 

Increased quantity and quality of 

recreational opportunities

Qualitative 

Discussion (Benefits 

and Cost Analysis) 

Reduction in pollutant loadings to 

impaired waters

 Section 6.4

Reduction in pollutant loadings to the 

Great Lakes and Chesapeake Bay

 Section 6.4

Reduction in loadings of metals, 

chlorides, and, TDS to receiving 

waters



Section 6.1

Reduction in nutrient loadings to 

receiving waters  

Section 6.1 and

Benefits and Cost 

Analysis a

 

Reduced risk of surface 

impoundment failures due to surface 

impoundment closures

 

Benefits and Cost 

Analysis a 

Reduced sediment contamination Qualitative 

Discussion (Benefits 

and Cost Analysis) 

Reduced pollutant leachate to ground 

water, reducing contamination and 

increasing availability of ground 

water resources

 

Benefits and Cost 

Analysis a 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-5 

Table 6-2. Description of Environmental Improvements 

from Preferred Regulatory Options 

Assessment 

Category

Description of Environmental 

Improvement

Improvement 

Quantified

Improvement 

Monetized More Information

Wildlife Reduced exposure among minks to 

pollutants that bioaccumulate in fish

 Section 6.2 and 

Section 6.3

Reduced exposure among eagles to 

pollutants that bioaccumulate in fish

 Section 6.2 and 

Section 6.3

Reduction in selenium concentrations 

in fish

 Section 6.2.2 and 

Section 6.3.3

Improved habitat and thus potential 

increase in threatened and 

endangered population 

 

Section 6.4 and 

Benefits and Cost 

Analysis a

Improved fisheries yield and harvest 

quality due to aquatic habitat 

improvement

Qualitative 

Discussion (Benefits 

and Cost Analysis)

Enhanced existence, option, and 

bequest values from improved 

ecosystem health

 

Benefits and Cost 

Analysis a 

Reduced risks to aquatic life from 

exposure to steam electric pollutants 

 Benefits and Cost 

Analysis a 

Reduced exposure to pollutants 

associated with the waste streams of 

concern in surface impoundments 

that serve as attractive nuisances

Qualitative 

Discussion (Section 

6.5) 

Reduced water usage Qualitative 

Discussion (Benefits 

and Cost Analysis)

Human 

Health

Reduced exposure to non-cancer 

pollutants for recreational and 

subsistence fishers

 

Section 6.2 and 

Section 6.3, Benefits 

and Cost Analysis a

Reduced cancer risk in recreational 

fishers and subsistence fishers  

Section 6.2 and 

Section 6.3, Benefits 

and Cost Analysis a

Reduced adverse health effects from 

reduction in-utero mercury exposure 

from maternal fish consumption

 

Benefits and Cost 

Analysis a 

Reduced adverse health effects from 

reduction in childhood exposure to 

lead from fish consumption

 

Benefits and Cost 

Analysis a 

Reduced adverse health effects from 

reduction in adult exposure to lead 

from fish consumption

Qualitative 

Discussion (Benefits 

and Cost Analysis)

Reduced adult mortality from air 

pollutant emissions

  Benefits and Cost 

Analysis a 

Reduced social cost of carbon b

  Benefits and Cost 

Analysis a

Reduced exposure to pollutants from 

recreational water uses

Qualitative 

Discussion (Benefits 

and Cost Analysis)
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-6 

Table 6-2. Description of Environmental Improvements 

from Preferred Regulatory Options 

Assessment 

Category

Description of Environmental 

Improvement

Improvement 

Quantified

Improvement 

Monetized More Information

Reduced injury associated with 

impoundment failures

Qualitative 

Discussion (Benefits 

and Cost Analysis) 

Reduction in number of immediate 

receiving waters exceeding fish 

consumption advisory screening 

values



Section 6.4

Acronyms: MCL (Maximum Contaminant Level); NRWQC (National Recommended Water Quality Criteria); TDS 

(Total Dissolved Solids).

a – The Benefits and Cost Analysis quantifies and monetizes individual environmental improvements for Options 1-

5, while inferring total benefits for Options 3a, 3b, and 4a. See Benefits and Cost Analysis for more detail.

b – Social cost of carbon is an estimate of the monetized damages associated with an incremental increase in carbon

emissions in a given year. It is intended to include (but is not limited to) changes in net agricultural productivity, 

human health, property damages from increased flood risk, and the value of ecosystem services due to climate 

change. 

6.1 LOADING REDUCTIONS UNDER THE PROPOSED REGULATORY OPTIONS 

EPA estimates that the preferred options will significantly reduce pollutant loadings to 

receiving waters for the 10 metals in the EA model and for other pollutants that can adversely 

affect surface waters, such as boron, manganese, nutrients, chlorides, and total dissolved solids 

(TDS). Table 6-3 and Table 6-4 present the reduction in pollutant discharge loadings under the 

regulatory options for the evaluated waste streams. 

As discussed in Section 4, the EA focused on toxic, bioaccumulative metals discharged to 

surface waters in the evaluated waste streams. EPA determined that the preferred ELG options 

will reduce these metal loadings by as much as 70 percent for arsenic and 77 percent for 

chromium VI (under Options 3a and 3b), 92 percent for selenium and 95 percent for manganese 

(under Option 3), and 96 percent for selenium and 97 percent for manganese (under Option 4a). 

In turn, these pollutant reductions will reduce the negative impacts on the environment and 

reduce the potential exposure of these contaminants to ecological and human receptors. The 

reduction in selenium loadings will significantly improve the water quality around the steam 

electric power plant discharge locations. Negative impacts from selenium on the environment 

and wildlife have been extensively documented in the literature (see Section 5.1). The reductions 

in mercury loadings will improve human health as mercury has been linked to decreased IQs in 

children when pregnant mothers have been exposed to mercury through fish consumption. 

Under Options 3a and 3b, EPA estimates that arsenic (a carcinogen) and chromium VI 

loadings will reduce by 70 percent or more. Cadmium (a suspected carcinogen), copper, lead, 

mercury, total phosphorus, thallium, and zinc will be reduced by 20 percent or more. Nickel, 

total nitrogen, and selenium loadings will reduce by 10 percent or more. 

Under Option 3, EPA estimates that arsenic (a carcinogen), cadmium (suspected 

carcinogen), chromium VI, manganese, selenium, and zinc loadings will reduce by 70 percent or 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-7 

more. Boron, copper, mercury, nickel, and total nitrogen loadings will be reduced by 50 percent 

or more. EPA calculated lead and thallium loading reductions to be 38 and 23 percent, 

respectively.

Under Option 4a, EPA estimates that arsenic (a carcinogen), cadmium (suspected 

carcinogen), chromium VI, manganese, mercury, total nitrogen, selenium, total phosphorus, and 

zinc loadings will reduce by 80 percent or more. Boron, copper, lead, nickel, TDS, and thallium 

loadings will be reduced by 55 percent or more. EPA calculated chlorides loading reductions to 

be 26 percent.

Manganese and boron, while not generally considered toxic at levels seen in the aquatic 

environment, have the highest and third highest toxic weighted pound equivalents (TWPEs) (see 

Section 3.2) under baseline conditions, respectively. Under the preferred options, the pollutant 

loadings for manganese and boron will decrease by 3 and 4 percent (under Option 3a), 4 and 22 

percent (under Option 3b), 95 and 55 percent (under Option 3), and 96 and 57 percent (under 

Option 4a), respectively. Toxicity studies have reported boron-related effects occurring in fish 

and ducks; however, EPA has not set a National Recommended Water Quality Criteria 

(NRWQC) for boron [WHO, 1998]. Although manganese can be toxic to humans at high levels, 

it is also an essential nutrient required to maintain health [WHO, 2011]. Manganese can 

bioaccumulate in lower organisms, such as phytoplankton, algae, mollusks, and some fish, but 

not in higher organisms [ATSDR, 2008b]. EPA did not include boron and manganese in the EA 

model due to their low risk of adverse effects on the aquatic ecosystem and lack of partition 

coefficient data needed for the model. 

As discussed in Section 3.2, nutrients (i.e., nitrogen and phosphorus) in excess quantities 

can adversely affect surface waters by causing oxygen-consuming algae blooms and creating 

“dead zones” where fish and shellfish cannot survive. EPA calculated that nitrogen loadings will 

reduce by 4.6 million pounds per year (15 percent) under Option 3a; 8.7 million pounds per year 

(29 percent) under Option 3b; 16.2 million pounds per year (53 percent) under Option 3; and 

24.8 million pounds per year (82 percent) under Option 4a. EPA calculated that phosphorus 

loadings will reduce by 211,000 pounds per year (31 percent) under Option 3a; 231,000 pounds 

per year (34 percent) under Option 3b; 269,000 pounds per year (39 percent) under Option 3; and 

496,000 pounds per year (73 percent) under Option 4a. The reduction in nutrients improves 

hypoxic areas (i.e., low oxygen surface waters) such as the Chesapeake Bay and the Gulf of 

Mexico (via reduced loadings to the Mississippi River Basin).

To protect freshwater fish and aquatic life, EPA recommends the following for chloride: 

criterion maximum concentration of 860 milligrams per liter (acute effects) and criterion 

continuous concentration of 230 milligrams per liter (chronic effects) [U.S. EPA, 2009d]. 

Exceeding these chloride levels in wastewater discharges can be harmful to animals and plants in 

non-marine surface waters and can disrupt ecosystem structure. Under the preferred options, 

annual chloride loadings to surface waters will be reduced by 30.8 million pounds (under Option 

3a), 209 million pounds (under Option 3b), 410 million pounds (under Option 3), and 434 

million pounds (under Option 4a). 

The pollutant parameter, TDS, is composed of dissolved solids such as chloride and 

metals. Under the preferred options, EPA calculated that annual TDS loadings to surface waters 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-8 

will be reduced by more than 400 million pounds (6 percent) under Option 3a, 1.5 billion pounds 

(21 percent) under Option 3b, 3 billion pounds (46 percent) under Option 3, and 4 billion pounds 

(57 percent) under Option 4a. This reduction is at least partially due to the reduction in total and 

dissolved metals discharged to receiving waters. 
6-9

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-3. Steam Electric Industry Pollutant Reductions for

Metals, Nutrients, Chlorides, and TDS Under Regulatory Options 

Pollutant

Reduction in Pollutant Loadings (lb/year) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Arsenic 441

(1%)

411

(1%)

55,800

(70%)

56,000

(71%)

56,200

(71%)

68,000

(86%)

77,500

(98%)

78,000

(98%)

Boron 1,710,000

(3%)

27,500,000

(51%)

2,200,000

(4%)

11,900,000

(22%)

29,700,000

(55%)

31,100,000

(57%)

32,200,000

(59%)

53,100,000

(98%)

Cadmium 15,300

(48%)

15,500

(49%)

6,820

(21%)

12,500

(39%)

22,300

(70%)

27,500

(86%)

31,300

(98%)

31,400

(98%)

Chromium 

VI

9.46

(<1%)

123

(1%)

9,050

(77%)

9,070

(77%)

9,170

(78%)

10,500

(89%)

11,500

(97%)

11,700

(99%)

Copper 2,780

(4%)

2,660

(4%)

32,600

(47%)

33,600

(48%)

35,300

(51%)

54,500

(78%)

68,800

(98%)

68,900

(99%)

Lead 538

(1%)

538

(1%)

23,900

(37%)

24,200

(38%)

24,500

(38%)

47,400

(74%)

63,800

(99%)

63,800

(99%)

Manganese 11,500,000

(79%)

13,400,000

(92%)

429,000

(3%)

5,200,000

(36%)

13,800,000

(95%)

14,000,000

(97%)

14,100,000

(97%)

14,400,000

(99%)

Mercury 759

(27%)

777

(28%)

1,010

(36%)

1,290

(46%)

1,790

(63%)

2,340

(83%)

2,780

(99%)

2,790

(99%)

Nickel 123,000

(43%)

123,000

(43%)

27,900

(10%)

72,500

(25%)

151,000

(53%)

228,000

(79%)

285,000

(99%)

285,000

(99%)

Selenium 103,000

(46%)

178,000

(79%)

30,000

(13%)

90,100

(40%)

208,000

(92%)

216,000

(96%)

222,000

(99%)

222,000

(99%)

Thallium 857

(1%)

1,990

(1%)

34,900

(21%)

35,600

(22%)

37,000

(23%)

110,000

(67%)

162,000

(99%)

163,000

(99%)

Zinc 193,000

(49%)

195,000

(50%)

92,000

(23%)

163,000

(41%)

287,000

(73%)

345,000

(88%)

390,000

(99%)

386,000

(98%)

Nitrogen,

total

1,520,000

(5%)

13,500,000

(44%)

4,550,000

(15%)

8,700,000

(29%)

16,200,000

(53%)

24,800,000

(82%)

29,300,000

(96%)

29,300,000

(96%)
6-10

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-3. Steam Electric Industry Pollutant Reductions for

Metals, Nutrients, Chlorides, and TDS Under Regulatory Options 

Pollutant

Reduction in Pollutant Loadings (lb/year) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Phosphorus, 

total

0 

(0%)

0 

(0%)

211,000

(31%)

231,000

(34%)

269,000

(39%)

496,000

(73%)

537,000

(79%)

553,000

(81%)

Chlorides 0 

(0%)

371,000,000

(23%)

30,800,000

(2%)

209,000,000

(13%)

410,000,000

(25%)

434,000,000

(26%)

460,000,000

(28%)

1,620,000,000

(99%)

TDS 1,350,000,000

(19%)

2,860,000,000

(40%)

429,000,000

(6%)

1,510,000,000

(21%)

3,290,000,000

(46%)

4,040,000,000

(57%)

4,580,000,000

(64%)

7,010,000,000

(98%)

Source: ERG, 2013g.

Acronyms: TDS (Total Dissolved Solids); lb/yr (pounds per year).

a – All values are rounded to three significant figures.

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction.
6-11

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-4. Steam Electric Industry Toxic Weighted Equivalent Pollutant Reductions for

Metals, Nutrients, Chlorides, and TDS Under Regulatory Options 

Pollutant

Reduction in Pollutant Loadings (TWPE/yr) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Arsenic 1,780

(1%)

1,660

(1%)

226,000

(71%)

226,000

(71%)

227,000

(71%)

275,000

(86%)

313,000

(98%)

315,000

(98%)

Boron 14,200

(3%)

230,000

(51%)

18,300

(4%)

99,100

(22%)

248,000

(55%)

260,000

(57%)

268,000

(59%)

443,000

(98%)

Cadmium 353,000

(48%)

358,000

(49%)

158,000

(21%)

288,000

(39%)

516,000

(70%)

636,000

(86%)

723,000

(98%)

725,000

(98%)

Chromium VI 4.89

(<1%)

63.7

(1%)

4,670

(77%)

4,690

(77%)

4,740

(78%)

5,420

(89%)

5,940

(98%)

6,020

(99%)

Copper 1,770

(4%)

1,690

(4%)

20,700

(47%)

21,300

(48%)

22,400

(50%)

34,600

(78%)

43,600

(98%)

43,700

(98%)

Lead 1,210

(1%)

1,210

(1%)

53,600

(37%)

54,100

(38%)

54,500

(38%)

106,000

(74%)

143,000

(99%)

143,000

(99%)

Manganese 808,000

(79%)

946,000

(93%)

30,200

(3%)

36,600

(4%)

973,000

(95%)

984,000

(96%)

992,000

(97%)

1,010,000

(99%)

Mercury 88,900

(27%)

91,000

(28%)

118,000

(36%)

151,000

(46%)

209,000

(63%)

274,000

(83%)

326,000

(99%)

327,000

(99%)

Nickel 13,400

(43%)

13,400

(43%)

3,040

(10%)

7,890

(25%)

16,400

(53%)

25,000

(80%)

31,100

(>99%)

31,100

(>99%)

Selenium 115,000

(46%)

200,000

(79%)

33,600

(13%)

101,000

(40%)

233,000

(92%)

242,000

(96%)

249,000

(99%)

249,000

(99%)

Thallium 881

(1%)

2,040

(1%)

35,900

(21%)

36,600

(22%)

38,000

(23%)

113,000

(67%)

167,000

(99%)

167,000

(99%)

Zinc 9,050

(49%)

9,150

(50%)

4,310

(23%)

7,630

(41%)

13,400

(73%)

16,200

(88%)

18,300

(99%)

18,100

(98%)

Nitrogen,

total

N/A N/A N/A N/A N/A N/A N/A N/A
6-12

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-4. Steam Electric Industry Toxic Weighted Equivalent Pollutant Reductions for

Metals, Nutrients, Chlorides, and TDS Under Regulatory Options 

Pollutant

Reduction in Pollutant Loadings (TWPE/yr) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Phosphorus, 

total

N/A N/A N/A N/A N/A N/A N/A N/A

Chlorides 0 

(0%)

9,030

(23%)

751

(2%)

5,090

(13%)

9,800

(25%)

10,600

(27%)

11,200

(28%)

39,500

(99%)

TDS N/A N/A N/A N/A N/A N/A N/A N/A

Source: ERG, 2013g.

Acronyms: TDS (Total Dissolved Solids); TWPE/yr (Toxic Weighted Pound Equivalents per year). 

N/A – The TWPE/yr is not provided for total nitrogen, total phosphorus, and TDS because EPA has not established a toxic weighting factor (TWF) for these 

pollutants.

a – All values are rounded to three significant figures.

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-13 

6.2 KEY ENVIRONMENTAL IMPROVEMENTS

The preferred options will result in substantial improvements to water quality, wildlife, 

and human health. EPA estimated that receiving water exceedances of the NRWQC will reduce 

under the preferred options by up to 29 percent (under Options 3a and 3b), 35 percent (under 

Option 3), and 55 percent (under Option 4a). EPA estimated that human exposures via fish 

consumption to pollutants with the potential to cause non-cancer health effects will decrease by 

up to 19 percent (under Option 3a), 21 percent (under Option 3b), 26 percent (under Option 3), 

and 47 percent (under Option 4a). EPA estimated that human exposures to pollutants that 

present a cancer risk will decrease by up to 40 percent (under Option 3a), 60 percent (under 

Options 3b and 3), and 80 percent (under Option 4a). EPA determined that these reductions will 

translate into lower exposure doses and a lower likelihood for adverse health effects to result. 

Table 6-5 presents a summary of the key environmental improvements associated with the five 

regulatory options in the immediate receiving waters evaluated in the EA. Results for the 

preferred options are discussed in the sections following the table. 

The receiving water model included a total of 297 immediate receiving waters (261 rivers 

and streams; 36 lakes, ponds, and reservoirs). Table 6-5 presents the number of receiving waters 

where negative impacts to water quality, wildlife, and human health are a concern due to 

pollutant discharges from steam electric power plants. For example, 147 of the 297 immediate 

receiving waters (49 percent) had concentrations of one or more pollutants that exceeded the 

criteria for human health (water and organism). The regulatory options evaluated for the 

proposed ELGs will improve receiving water quality and reduce impacts to wildlife and human 

receptors. Under Options 1 and 2, most of the water quality, wildlife, and human health 

exceedances will be reduced by between 0 to 20 percent of the immediate receiving waters. The 

number of immediate receiving waters with freshwater acute NRWQC exceedances is reduced 

by 23 percent under Options 1 and 2. Under Options 3a and 3b, the number of immediate 

receiving waters with water quality exceedances is reduced by between 10 and 29 percent. The 

reduction in immediate receiving waters with wildlife and human health benchmark exceedances 

under Options 3a and 3b falls mostly into the 16 to 40 percent reduction range. Under Option 3, 

the number of immediate receiving waters with water quality exceedances is reduced by between

14 to 35 percent. The reduction in immediate receiving waters with wildlife and human health 

benchmark exceedances under Option 3 falls mostly into the 21 to 50 percent reduction range. 

The risk to recreational fishers (children) is reduced below benchmarks in 60 percent of the 

receiving waters that exceeded under baseline. Under Option 4a, most of the water quality, 

wildlife, and human health exceedances will be reduced by more than 35 percent of immediate 

receiving waters. Under Options 4 and 5, the number of immediate receiving waters exceeding 

benchmarks is reduced by more than 50 percent for all benchmarks evaluated. 
6-14

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-5. Key Environmental Improvements Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Water Quality Results

Freshwater Acute 

NRWQC

31 10% 24

(23%)

24

(23%)

22

(29%)

22

(29%)

20

(35%)

14

(55%)

5

(84%)

5

(84%)

Freshwater Chronic 

NRWQC

67 23% 62

(7%)

56

(16%)

57

(15%)

56

(16%)

54

(19%)

39

(42%)

16

(76%)

16

(76%)

Human Health Water 

and Organism NRWQC

147 49% 147

(0%)

147

(0%)

127

(14%)

125

(15%)

120

(18%)

86

(41%)

48

(67%)

50

(66%) c

Human Health 

Organism-only 

NRWQC

99 33% 99

(0%)

99

(0%)

89

(10%)

88

(11%)

85

(14%)

61

(38%)

28

(72%)

24

(76%)

Drinking Water

MCL

59 20% 58

(2%)

54

(8%)

53

(10%)

52

(12%)

51

(14%)

36

(39%)

5

(92%)

5

(92%)

Wildlife Results

Fish Ingestion NEHC 

for Minks

99 33% 91

(8%)

83

(16%)

76

(23%)

75

(24%)

69

(30%)

49

(51%)

15

(85%)

15

(85%)

Fish Ingestion NEHC 

for Eagles

129 43% 118

(9%)

110

(15%)

104

(19%)

103

(20%)

97

(25%)

69

(47%)

17

(87%)

17

(87%)

Human Health Results—Non-Cancer

Non-cancer reference 

dose for child 

(recreational)

124 42% 109

(12%)

106

(15%)

100

(19%)

98

(21%)

92

(26%)

66

(47%)

12

(90%)

10

(92%)

Non-cancer reference 

dose for adult 

(recreational)

128 43% 114

(11%)

109

(15%)

104

(19%)

102

(20%)

96

(25%)

69

(46%)

12

(91%)

10

(92%)

Non-cancer reference 

dose for child 

(subsistence)

196 66% 179

(9%)

173

(12%)

165

(16%)

163

(17%)

155

(21%)

111

(43%)

39

(80%)

33

(83%)

Non-cancer reference 

dose for adult 

(subsistence)

189 64% 170

(10%)

167

(12%)

159

(16%)

157

(17%)

149

(21%)

106

(44%)

35

(81%)

30

(84%)
6-15

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-5. Key Environmental Improvements Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Human Health Results—Cancer

Arsenic cancer risk for 

child (recreational)

5 2% 5

(0%)

5

(0%)

3

(40%)

2

(60%)

2

(60%)

1

(80%)

1

(80%)

1

(80%)

Arsenic cancer risk for 

adult (recreational)

12 4% 12

(0%)

12

(0%)

8

(33%)

8

(33%)

7

(42%)

5

(58%)

2

(83%)

2

(83%)

Arsenic cancer risk for 

child (subsistence)

9 3% 9

(0%)

9

(0%)

6

(33%)

6

(33%)

5

(44%)

4

(56%)

2

(78%)

2

(78%)

Arsenic cancer risk for 

adult (subsistence)

27 9% 25

(7%)

25

(7%)

20

(26%)

20

(26%)

19

(30%)

14

(48%)

3

(89%)

3

(93%)

Source: ERG, 2013h; ERG, 2013i; ERG, 2013l.

Acronyms: MCL (Maximum Contaminant Level); NEHC (No Effect Hazard Concentration); NRWQC (National Recommended Water Quality Criteria).

a – The receiving water model included a total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) and evaluated impacts 

associated with the evaluated waste streams.

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 

c – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams together in a chemical precipitation plus biological 

treatment system. Under Regulatory Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for some immediate 

receiving waters the metal loadings will increase under Regulatory Option 5 compared to Regulatory Option 4, resulting in the percent reductions of exceedances 

being lower under Regulatory Option 5. See the Incremental Costs and Pollutant Removals for Proposed Effluent Limitation Guidelines and Standards for the 

Steam Electric Generating Point Source Category Report (DCN SE01957) for further discussion of the regulatory option loadings.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-16 

6.2.1 Improvements in Water Quality Under the Preferred Options

EPA estimated that reduced pollutant loadings to surface waters associated with the 

proposed Steam Electric ELGs will significantly improve water quality by reducing exceedances 

of the NRWQC and maximum contaminant levels (MCLs) by 10 to 29 percent (under Options 3a 

and 3b), 14 to 35 percent (under Option 3), and 38 to 55 percent (under Option 4a). 

Improvements in water quality are driven by reductions in exceedances for arsenic, selenium, 

cadmium, and thallium. 

EPA determined that the largest reductions in NRWQC exceedances are attributed to 

reduced loadings of cadmium and selenium under Options 3a, 3b, and 3 and reduced loadings of 

cadmium, selenium, arsenic, and thallium under Option 4a. Sublethal and lethal impacts from 

chronic exposure to cadmium (e.g., skeletal malformations and organ damage), selenium (e.g., 

fish kills, organ damage, and reproductive failure), arsenic (e.g., developmental abnormalities, 

behavioral impairments, and metabolic failure), and thallium (e.g., neurological symptoms, 

gastrointestinal effects, and reproductive failure) are well documented in the literature following 

exposure to combustion wastewater [ATSDR, 2008a; Coughlan and Velte, 1989; Lemly, 1985b; 

Nagle et al., 2001; NRC, 2006; Rowe et al., 2002; U.S. EPA, 2009a; U.S. EPA, 2011f]. Due to 

the substantial reductions in these pollutants under the preferred options, EPA projects that 

aquatic organisms will be less susceptible to the adverse impacts described above. 

EPA estimates that 33 to 49 percent (99 and 147 immediate receiving waters, 

respectively) of receiving waters currently exceed NRWQC for the protection of human health. 

EPA estimated that these immediate receiving water exceedances, primarily driven by the 

discharge of total arsenic and total thallium, will decrease under the preferred options by 10 to 15 

percent (under Options 3a and 3b), 14 to 18 percent (under Option 3), and 38 to 41 percent 

(under Option 4a). EPA determined that reductions in exposure to arsenic and thallium under the 

preferred options will lower the number of immediate receiving waters that exceed NRWQC 

designed to protect public health. By reducing MCL exceedances by 10 percent (under Option 

3a), 12 percent (under Option 3b), 14 percent (under Option 3), and 39 percent (under Option 

4a), pollutant loading reductions under the preferred options will improve the quality of source 

water available to drinking water treatment plants downstream from steam electric power plants. 

In addition to the reduction in NRWQC and MCL exceedances, EPA determined a 

quantifiable improvement in overall water quality to result from the preferred options. EPA 

calculated that, on average, receiving water concentrations of the 10 metals evaluated in the EA 

will be reduced by 22 to 36 percent (under Options 3a and 3b), 25 to 48 percent (under Option 

3), and 47 to 60 percent (under Option 4a), considerably improving the water quality in the 

immediate receiving waters located downstream from steam electric power plants.

6.2.2 Reduced Threat to Wildlife Under the Preferred Option

In the EA, EPA evaluated multiple threats to wildlife, including exposure of aquatic 

organisms to contaminated sediments and receiving waters, bioaccumulation of metals in fish 

tissue, and negative impacts on wildlife that consume fish. The combination of both lethal and 

sublethal effects (e.g., changes to morphology, behavior, and metabolism) of exposure to 

combustion wastewater can cause cascading effects through the food web. 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-17 

As discussed in Section 6.2.1, EPA calculated that the number of immediate receiving 

waters with the potential to pose an acute or chronic threat to wildlife will decrease under the 

proposed Steam Electric ELGs, resulting in numerous unquantifiable improvements to wildlife 

populations and communities surrounding steam electric power plants (e.g., reduced impacts to 

population density and species diversity as discussed in Section 3.3). EPA then estimated that 

average fish tissue pollutant concentrations among the pollutants evaluated in the EA will 

decrease by as much as 33 percent under Option 3a, 36 percent under Option 3b, 48 percent 

under Option 3, and 60 percent under Option 4a (in the case of selenium). EPA projects that 

these pollutant concentration reductions will result in a significant improvement in the health of 

fish populations and the quality of fish available for consumption by both humans and wildlife 

near steam electric power plants. 

Studies and reports have highlighted the concern over the potential for bioaccumulative 

metals (e.g., selenium) commonly found in combustion wastewater to transfer from the aquatic 

environment and accumulate in terrestrial food webs surrounding steam electric power plants. 

EPA evaluated the threats to minks and eagles from consuming fish contaminated by combustion 

wastewater as an indication of the potential for pollutants to bioaccumulate and impact higher 

order species in the food chain. EPA estimates that exceedances of the no effect hazard 

concentration (NEHC) for eagles and minks will decrease by 19 percent and 23 percent (under 

Option 3a), 20 percent and 24 percent (under Option 3b), 25 percent and 30 percent (under 

Option 3) and by 47 percent and 51 percent (under Option 4a), respectively, signifying that the 

preferred options will decrease the threat from bioaccumulative metals in the food chain. 

6.2.3 Reduced Human Health Cancer Risk Under the Preferred Option

Under baseline conditions, EPA estimates that 27 immediate receiving waters (9 percent) 

would contain fish contaminated with inorganic arsenic that would present cancer risks above the 

1-in-a-million threshold for one or more of the cohorts evaluated. The preferred options reduce 

the cancer risk for both recreational and subsistence fishers across all cohorts. EPA calculated 

that, under the preferred options, the number of immediate receiving waters whose fish exceed 

this cancer risk threshold will be reduced by between 26 to 40 percent (under Option 3a), 26 to 

60 percent (under Option 3b), 30 to 60 percent (under Option 3), and 48 to 80 percent (under 

Option 4a), depending on the cohort. 

6.2.4 Reduced Threat of Non-Cancer Human Health Effects Under the Preferred Option

Reductions in pollutant loadings from the proposed ELGs will reduce the number of 

immediate receiving waters with contaminated fish that pose a potential threat to cause noncancer health effects in humans. EPA estimates that the number of immediate receiving waters 

whose fish pose non-cancer health risks will be reduced by 16 to 19 percent (under Option 3a), 

17 to 21 percent (under Option 3b), 21 to 26 percent (under Option 3), and 43 to 47 percent 

(under Option 4a), depending on the cohort. Chronic exposure to metals in combustion 

wastewater has the potential to reduce neurological and developmental functions and affect the 

circulatory, respiratory, and digestive systems of exposed populations. As discussed in Section 

6.2.2, EPA found that the pollutant concentrations in fish tissue will decrease under the preferred 

options, improving the quality of fish available to recreational and subsistence fishers and 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-18 

subsequently lowering exposures to toxic metals and the potential for non-cancer health effects 

to occur. 

EPA determined that the potential for non-cancer health effects to occur are driven by 

selenium, cadmium, mercury (as methylmercury), and to a lesser degree, thallium pollutant 

loadings. EPA calculated that the proposed ELGs will significantly reduce these potential effects 

by reducing the number of immediate receiving waters with exposure doses due to fish 

consumption that exceed the reference doses for these pollutants, as described below:

• For selenium, these exceedances will decrease by up to 50 percent (under Option 3a), 

52 percent (under Option 3b), 69 percent (under Option 3), and 77 percent (under 

Option 4a), depending on the cohort. 

• For cadmium, these exceedances will decrease by up to 38 percent (under Option 3a), 

42 percent (under Option 3b), 54 percent (under Option 3), and 69 percent (under 

Option 4a), depending on the cohort. 

• For methylmercury, these exceedances will decrease by up to 21 percent (under 

Option 3a), 22 percent (under Option 3b), 29 percent (under Option 3), and 49 

percent (under Option 4a), depending on the cohort. 

• For thallium, these exceedances will decrease by up to 14 percent (under Options 3a 

and 3b), 18 percent (under Option 3), and 43 percent (under Option 4a), depending on 

the cohort. 

EPA determined that the reduced loadings for the pollutants above will reduce the 

potential threat for non-cancer health effects (e.g., nausea, abdominal pain, sleep disorders, 

muscular problems, and cardiovascular disease) in humans that consume contaminated fish from 

these receiving waters. 

Although the EA did not directly assess the potential non-cancer health effects posed by 

lead,40 the proposed ELGs will lower the total loadings of lead to the environment, thus reducing 

the potential threat of hypertension, coronary heart disease, and impaired cognitive function in 

exposed populations. For children in particular, lead exposure can cause additional negative 

impacts, such as hyperactivity, behavioral and attention difficulties, delayed mental 

development, and motor and perceptual skill deficits. The benefits to children from the reduced 

discharge of lead are discussed in the Benefits and Cost Analysis.

6.3 POLLUTANT-SPECIFIC IMPROVEMENTS

In the above analyses, EPA identified several key pollutants (i.e., arsenic, mercury, 

selenium, cadmium, and thallium) as the primary drivers for the improvements in water quality, 

wildlife, and human health attributed to the preferred options. This section highlights the 

pollutant-specific environmental improvements calculated to result from Options 3a, 3b, 3, and 

4a. It also presents a qualitative discussion of the loading reductions under the preferred options 

 

40 Currently, there is no reference dose for lead—there is no safe level for ingestion of lead (see EPA’s Integrated 

Risk Information System (IRIS) website: http://www.epa.gov/IRIS/).
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-19 

for the 10 metals included in the EA model and other pollutants with high loading impacts on 

receiving waters (i.e., boron, manganese, nutrients, TDS, and chlorides). 

6.3.1 Arsenic

Arsenic is a toxic and carcinogenic metal. EPA’s baseline analysis of the evaluated waste 

streams identified arsenic as a key pollutant causing negative impacts to the surface water, 

including receiving water exceedances of water quality standards, threats to mink who consume 

contaminated fish, risk of cancer and non-cancer health effects in humans that consume 

contaminated fish. The preferred options will reduce the number of immediate receiving waters 

exceeding acute and chronic NRWQC from seven to four under Options 3a and 3b, three under 

Option 3, and two under Option 4a. This reduction in arsenic discharged to receiving waters will 

reduce negative effects on aquatic organisms, such as liver tissue death, developmental 

abnormalities, behavioral impairments, metabolic failure, growth reduction, and appetite loss 

[NRC, 2006; Rowe et al., 2002; U.S. EPA, 2011f]. 

Arsenic, along with mercury and selenium, can readily bioaccumulate in exposed biota 

(e.g., fish). The bioaccumulation of these pollutants is of particular concern due to the potential 

for impacting higher trophic levels, local terrestrial environments, and transient species, in 

addition to the aquatic organisms directly exposed to the wastewater. Aquatic systems with long 

residence times and potential contamination with bioaccumulative pollutants often experience 

persistent environmental effects after receiving combustion wastewater. The preferred options 

will reduce the bioaccumulation of arsenic in the food web and reduce the number of immediate 

receiving waters exceeding NEHCs for minks from two to one under Options 3a, 3b, 3, and 4a. 

Non-cancer human health effects from arsenic exposure include cardiovascular, 

pulmonary, immunological, neurological, and endocrine (e.g., diabetes) effects. Arsenic has been 

linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate [U.S. EPA, 

2001]. The preferred options will reduce human exposure to arsenic through fish consumption 

and thus lower the potential for exposed populations to develop arsenic-related cancer and noncancer health effects. Table 6-6 presents the key environmental improvements as a result of 

reduced arsenic discharges under the regulatory options. 
6-20

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-6. Key Environmental Improvements for Arsenic Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Water Quality Results

Freshwater Acute 

NRWQC

6 2% 6

(0%)

6

(0%)

4

(33%)

3

(50%)

3

(50%)

2

(67%)

1

(83%)

1

(83%)

Freshwater Chronic 

NRWQC

7 2% 7

(0%)

7

(0%)

4

(43%)

4

(43%)

3

(57%)

2

(71%)

2

(71%)

2

(71%)

Human Health Water 

and Organism NRWQC

147 49% 147

(0%)

147

(0%)

125

(15%)

123

(16%)

120

(18%)

87

(41%)

48

(67%)

50

(66%) c

Human Health 

Organism-only 

NRWQC

96 32% 96

(0%)

96

(0%)

84

(13%)

84

(13%)

82

(15%)

60

(38%)

28

(71%)

24

(75%)

Drinking Water

MCL

19 6% 19

(0%)

19

(0%)

13

(32%)

13

(32%)

12

(37%)

9

(53%)

2

(89%)

2

(89%)

Wildlife Results

Fish Ingestion NEHC 

for Minks

2 1% 2

(0%)

2

(0%)

1

(50%)

1

(50%)

1

(50%)

1

(50%)

0

(100%)

0

(100%)

Fish Ingestion NEHC 

for Eagles

0 0% 0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

Human Health Results—Non-Cancer

Non-cancer reference 

dose for child 

(recreational)

0 0% 0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

Non-cancer reference 

dose for adult 

(recreational)

0 0% 0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

0

(N/A)

Non-cancer reference 

dose for child 

(subsistence)

3 1% 3

(0%)

3

(0%)

2

(33%)

2

(33%)

2

(33%)

1

(67%)

1

(67%)

1

(67%)

Non-cancer reference 

dose for adult 

(subsistence)

2 1% 2

(0%)

2

(0%)

1

(50%)

1

(50%)

1

(50%)

1

(50%)

0

(100%)

0

(100%)
6-21

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-6. Key Environmental Improvements for Arsenic Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Human Health Results—Cancer

Arsenic cancer risk for 

child (recreational)

5 2% 5

(0%)

5

(0%)

3

(40%)

2

(60%)

2

(60%)

1

(80%)

1

(80%)

1

(80%)

Arsenic cancer risk for 

adult (recreational)

12 4% 12

(0%)

12

(0%)

8

(33%)

8

(33%)

7

(42%)

5

(58%)

2

(83%)

2

(83%)

Arsenic cancer risk for 

child (subsistence)

9 3% 9

(0%)

9

(0%)

6

(33%)

6

(33%)

5

(44%)

4

(56%)

2

(78%)

2

(78%)

Arsenic cancer risk for 

adult (subsistence)

27 9% 25

(7%)

25

(7%)

20

(26%)

20

(26%)

19

(30%)

14

(48%)

3

(89%)

2

(93%)

Source: ERG, 2013h; ERG, 2013i; ERG, 2013l.

Acronyms: MCL (Maximum Contaminant Level); NEHC (No Effect Hazard Concentration); N/A (Not Applicable, no exceedances at baseline conditions to 

compare option results); NRWQC (National Recommended Water Quality Criteria).

a – The receiving water model included a total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs).

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 

c – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams together in a chemical precipitation plus biological 

treatment system. Under Regulatory Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for some immediate 

receiving waters the metal loadings will increase under Regulatory Option 5 compared to Regulatory Option 4, resulting in the percent reductions of exceedances 

being lower under Regulatory Option 5. See the Incremental Costs and Pollutant Removals for Proposed Effluent Limitation Guidelines and Standards for the 

Steam Electric Generating Point Source Category Report (DCN SE01957) for further discussion of the regulatory option loadings.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-22 

6.3.2 Mercury

As discussed in Section 5.3.2, estimated fish tissue concentrations for mercury (and 

selenium) exceed levels that have the potential to cause reduced reproductive success in exposed 

mink and eagle populations. EPA estimated that the preferred options will reduce the number of 

immediate receiving waters with fish tissue concentrations that exceed the mercury NEHC for 

eagles and minks by 19 and 24 percent (under Option 3a), 20 and 26 percent (under Option 3b), 

26 and 33 percent (under Option 3), and 47 and 52 percent (under Option 4a), respectively. 

These reductions are representative of the potential improvement in exposure to mercury above 

effects thresholds in other wildlife that consume fish from these receiving waters.

People in the United States are mainly exposed to methylmercury through the ingestion 

of contaminated fish and shellfish. For fetuses, infants, and children, the primary health effect of 

methylmercury is impaired neurological development. Methylmercury exposure in the womb, 

which can result from a mother’s consumption of fish and shellfish that contain methylmercury, 

can adversely affect a baby’s growing brain and nervous system. Impacts on cognitive thinking, 

memory, attention, language, and fine motor and visual spatial skills have been seen in children 

who were exposed to methylmercury in the womb. 

Under baseline pollutant loadings, EPA estimates that fish methylmercury concentrations 

pose a non-cancer threat to subsistence fishers in approximately 62 to 65 percent of immediate 

receiving waters. For recreational fishers, fish methylmercury concentrations pose a non-cancer 

threat in approximately 40 to 42 percent of the immediate receiving waters. EPA calculated that

fish tissue concentrations of methylmercury will decrease and, as a result, the number of 

immediate receiving waters with exposure doses from fish consumption that exceed the 

methylmercury reference dose will be reduced by up to 21 percent (under Option 3a), 22 percent 

(under Option 3b), 29 percent (under Option 3), and 49 percent (under Option 4a). Several of the 

steam electric plants addressed by this ELG discharge to receiving waters that are under a fish 

advisory for mercury (see Section 3.4.2). The preferred options result in reduced mercury 

loadings to receiving waters with fish advisories for mercury and for impaired waters (see 

Section 6.4). Table 6-7 presents the key environmental improvements as a result of reduced 

mercury discharges under the regulatory options. 
6-23

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-7. Key Environmental Improvements for Mercury Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Water Quality Results

Freshwater Acute 

NRWQC

2 1% 1 

(50%)

1 

(50%)

1 

(50%)

0 

(100%)

0 

(100%)

0 

(100%)

0 

(100%)

0 

(100%)

Freshwater Chronic 

NRWQC

2 1% 1 

(50%)

1 

(50%)

1 

(50%)

0 

(100%)

0 

(100%)

0 

(100%)

0 

(100%)

0 

(100%)

Human Health Water 

and Organism NRWQC

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Human Health 

Organism-only 

NRWQC

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Drinking Water 

MCL

0 0% 0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

Wildlife Results

Fish Ingestion NEHC 

for Minks

96 32% 78

(19%)

78

(19%)

73

(24%)

71

(26%)

64

(33%)

46

(52%)

6 

(94%)

6 

(94%)

Fish Ingestion NEHC 

for Eagles

127 43% 109

(14%)

107

(16%)

103

(19%)

101

(20%)

94

(26%)

67

(47%)

10

(92%)

10

(92%)

Human Health Results—Non-Cancer

Non-cancer reference 

dose for child 

(recreational)

119 40% 101

(15%)

99

(17%)

94

(21%)

93

(22%)

85

(29%)

61

(49%)

10

(92%)

8 

(93%)

Non-cancer reference 

dose for adult 

(recreational)

124 42% 106

(15%)

103

(17%)

99

(20%)

98

(21%)

90

(27%)

64

(48%)

10

(92%)

8 

(94%)
6-24

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-7. Key Environmental Improvements for Mercury Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Non-cancer reference 

dose for child 

(subsistence)

193 65% 175

(9%)

168

(13%)

162

(16%)

160

(17%)

150

(22%)

107

(45%)

33

(83%)

27

(86%)

Non-cancer reference 

dose for adult 

(subsistence)

185 62% 166

(10%)

161

(13%)

154

(17%)

152

(18%)

143

(23%)

102

(45%)

30

(84%)

23

(88%)

Source: ERG, 2013h; ERG, 2013i; ERG, 2013l.

Acronyms: MCL (Maximum Contaminant Level); N/A (Not Applicable, no benchmark for comparison); NEHC (No Effect Hazard Concentration); NRWQC 

(National Recommended Water Quality Criteria).

a – The receiving water model included a total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs).

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-25 

6.3.3 Selenium

Selenium was one of the primary pollutants identified in the literature and by EPA as 

causing documented environmental impacts to fish and wildlife. EPA reviewed over 100 case 

studies on selenium discharges and their environmental impacts, and found that 80 case studies 

showed damages to surface water quality and 43 case studies showed damages to ground water 

quality.41 For more information on the case studies, refer to Section 3.5. 

Studies have shown that selenium can bioaccumulate to toxic levels in organisms 

inhabiting aquatic environments with low selenium concentrations. In surface waters, selenium 

can accumulate and biomagnify to toxic levels in aquatic organisms and pose a lethal threat to 

fish at the top of the trophic structure [Lemly, 1985a]. Studies concluded that elevated selenium 

concentrations were likely the primary factor contributing to fish kills, decreasing population 

density, and community diversity in lakes and reservoirs that receive combustion wastewater 

[Coughlan and Velte, 1989; Crutchfield and Ferguson, 2000a; Crutchfield, 2000b; Cumbie and 

Van Horn, 1978]. In addition, the bioaccumulative properties of selenium (and other combustion 

pollutants) can lead to long recovery times associated with many of the ecological impacts 

[Rowe et al., 2002; NRC, 2006]. EPA estimates that immediate receiving water concentrations of 

total selenium due to combustion wastewater discharges will decrease by 33 percent on average 

(under Option 3a), 36 percent on average (under Option 3b), 48 percent on average (under 

Option 3), and 60 percent on average (under Option 4a). This will result in decreased 

concentrations of selenium that bioaccumulate or persist in the aquatic environment. The 

preferred options will result in a 38 percent reduction (under Option 3a), 40 percent reduction 

(under Option 3b), 55 percent reduction (under Option 3), and 67 percent reduction (under 

Option 4a) in the number of immediate receiving waters exceeding chronic aquatic life NRWQC 

and a 50 percent reduction (under Option 3a), 55 percent reduction (Option 3b), 75 percent 

reduction (Option 3), and 80 percent reduction (Option 4a) in the number of immediate receiving 

waters exceeding a drinking water MCL.

The sublethal effects of selenium include negative impacts to growth, reproduction, and 

survival of susceptible organisms, including various fish and amphibian species. In surface 

waters contaminated with combustion wastewater, scientists observed that these fish and 

amphibian species developed sublethal symptoms such as accumulation of selenium in tissue 

causing histopathological effects and in the blood, decreased growth, changes in weight, 

abnormal morphology, and reduced hatching success [Coughlan and Velte, 1989; Sager and 

Colfield, 1984; Sorensen et al., 1982, 1983, 1988; Sorensen and Bauer, 1984a; Sorensen et al., 

1984b]. Selenium accumulates most significantly in the liver and reproductive tissues in the 

majority of species and causes negative reproduction and histopathological impacts [Baumann 

and Gillespie, 1986]. As an assessment of the potential for sublethal effects to occur in fish, EPA 

compared modeled and estimated fish tissue concentrations of selenium to selenium 

concentrations where a negative impact occurred as documented in literature [Baumann and 

Gillespie, 1986]. EPA evaluated fish for two trophic levels: 

• Trophic level 4 (T4), largemouth bass (Micropterus salmoides). 

 

41 Note that one plant may impact both surface water and ground water.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-26 

• Trophic level 3 (T3), bluegill (Lepomis macrochirus). Female bluegill population 

accumulated selenium concentrations 1,000 times greater than in the water from 

which the fish were collected [Baumann and Gillespie, 1986]. 

Under baseline conditions, EPA estimates that T4 fish will exhibit selenium 

concentrations above levels documented in the literature to cause negative reproductive and 

histopathological effects in 18 percent (54) of immediate receiving waters. EPA estimates that 

T3 fish will exceed these negative effects thresholds in 13 percent (40) of immediate receiving 

waters. Table 6-8 presents the percent reduction in the number of immediate receiving waters 

with selenium fish tissue concentrations above the literature values for each regulatory option. 

EPA determined that selenium concentrations in T4 fish will improve to below the 

negative effects concentrations documented in the literature in 26 percent (under Option 3a), 28 

percent (under Option 3b), 37 percent (under Option 3), and 52 percent (under Option 4a) of 

immediate receiving waters whose fish currently exceed those thresholds. Similarly, EPA 

determined that selenium concentrations in T3 fish will improve to below the negative effects 

concentrations documented in the literature in 44 percent (under Option 3a), 48 percent (under 

Option 3b), 64 percent (under Option 3), and 73 percent (under Option 4a) of immediate 

receiving waters whose fish currently exceed those thresholds. 

The reduction in selenium loadings and reduced bioaccumulation in the environment 

under the preferred options will reduce the number of immediate receiving waters with fish 

tissue concentrations exceeding the NEHC for selenium for eagles and minks by 28 and 29 

percent (under Option 3a), 30 and 31 percent (under Option 3b), 41 and 42 percent (under Option 

3), and 57 and 56 percent (under Option 4a), respectively. These reductions are representative of 

the likely improvements to selenium exposure above effects thresholds in other wildlife that 

consume fish from these receiving waters and are indications of the potential improvements in 

bioaccumulation of metals in the broader food web near steam electric power plants. 

EPA estimates that intake doses resulting 

from fish selenium concentrations that pose a noncancer threat to recreational fishers and 

subsistence fishers will decrease in up to 50 and 

32 percent of immediate receiving waters (under 

Option 3a), 52 and 34 percent of immediate 

receiving waters (under Option 3b), 69 and 45 

percent of immediate receiving waters (under 

Option 3), and 88 and 76 percent of immediate 

receiving waters (under Option 4a), respectively. 

This reduced the threat for developing non-cancer 

health effects associated with selenium such as 

pulmonary edema and lesions of the lung; 

cardiovascular effects such as tachycardia; 

gastrointestinal effects including nausea, vomiting, diarrhea, and abdominal pain; effects on the 

liver; and neurological effects such as aches, irritability, chills, and tremors [U.S. EPA, 2000b]. 

Table 6-9 presents the key environmental improvements as a result of reduced selenium 

discharges under the regulatory options. 

Selenium is known to cause fish deformities at high 

levels, such as these from Belews Lake, NC.
6-27

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-8. Comparison of Estimated Selenium Concentrations in Fish to Documented Literature Fish Impacts

Wildlife 

Affected/ 

Trophic 

Level

Documented Impact 

Selenium 

Concentration b

(μg/g)

Immediate Receiving 

Waters Exceeding 

Literature Value Under 

Baseline Conditions a,c

Number of Immediate Receiving Waters Still Impacted Under Regulatory Options

(Percent Reduction from Baseline Conditions) a

Number Percentage

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Largemouth 

bass/T4

Female carcass = 2.86 53 18% 52

(2%)

39

(26%)

40

(25%)

39

(26%)

34

(36%)

26

(51%)

16

(70%)

21

(60%) d

Male carcass = 2.63 54 18% 52

(4%)

39

(28%)

40

(26%)

39

(28%)

34

(37%)

26

(52%)

16

(70%)

21

(61%) d

Bluegill/T3 Female carcass = 2.74 40 13% 35

(13%)

23

(43%)

23

(43%)

21

(48%)

15

(63%)

11

(73%)

8

(80%)

8

(80%)

Male carcass = 4.64 36 12% 30

(17%)

20

(44%)

20

(44%)

19

(47%)

13

(64%)

10

(72%)

6

(83%)

6

(83%)

Source: Baumann and Gillespie, 1986; ERG, 2013h; ERG, 2013i; ERG, 2013j; ERG, 2013l. 

Acronym: μg/g (micrograms per gram) 

Note: A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were included in the wildlife model. 

a – These values are the sum and percentage of rivers, streams, lakes, ponds, and reservoirs impacted. >0 to 20 percent reduction; 21 to 40 percent reduction; 41-

60 percent reduction; >60 percent reduction. 

b – The study concluded that the selenium accumulating in the fish can have negative reproductive and histopathological effects.

c – This represents the number of unique immediate receiving waters that exceeded a standard.

d – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams together in a chemical precipitation plus biological 

treatment system which may result in leachate switching receiving waters to be discharged in the same receiving water as FGD. Under Regulatory Option 5 for 

these plants, leachate is only treated with a chemical precipitation system and is discharged to the original designated receiving water; therefore, due to changes 

in receiving waters between Regulatory Options 4 and 5, the metal loadings at an immediate receiving water level may increase under Regulatory Option 5 

compared to Regulatory Option 4, resulting in the percent reductions of exceedances being lower under Regulatory Option 5.
6-28

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-9. Key Environmental Improvements for Selenium Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Water Quality Results

Freshwater Acute 

NRWQC

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Freshwater Chronic 

NRWQC

42 14% 38

(10%)

26

(38%)

26

(38%)

25

(40%)

19

(55%)

14

(67%)

11

(74%)

10

(76%)

Human Health Water 

and Organism NRWQC

13 4% 10

(23%)

7 

(46%)

6 

(54%)

6 

(54%)

3 

(77%)

2 

(85%)

2 

(85%)

2 

(85%)

Human Health 

Organism-only 

NRWQC

0 0% 0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

0 

(N/A)

Drinking Water

MCL

20 7% 17

(15%)

10

(50%)

10

(50%)

9 

(55%)

5 

(75%)

4 

(80%)

3 

(85%)

3 

(85%)

Wildlife Results

Fish Ingestion NEHC 

for Minks

48 16% 47

(2%)

34

(29%)

34

(29%)

33

(31%)

28

(42%)

21

(56%)

13

(73%)

13

(73%)

Fish Ingestion NEHC 

for Eagles

46 15% 45

(2%)

32

(30%)

33

(28%)

32

(30%)

27

(41%)

20

(57%)

12

(74%)

12

(74%)

Human Health Results—Non-Cancer

Non-cancer reference 

dose for child 

(recreational)

25 8% 24

(4%)

14

(44%)

13

(48%)

12

(52%)

8 

(68%)

6 

(76%)

3 

(88%)

3 

(88%)

Non-cancer reference 

dose for adult 

(recreational)

26 9% 25

(4%)

14

(46%)

13

(50%)

13

(50%)

8 

(69%)

6 

(77%)

3 

(88%)

3 

(88%)
6-29

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-9. Key Environmental Improvements for Selenium Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Non-cancer reference 

dose for child 

(subsistence)

45 15% 44

(2%)

30

(33%)

31

(31%)

30

(33%)

25

(44%)

19

(58%)

11

(76%)

13

(71%) c

Non-cancer reference 

dose for adult 

(subsistence)

44 15% 42

(5%)

29

(34%)

30

(32%)

29

(34%)

24

(45%)

18

(59%)

11

(75%)

13

(70%) c

Source: ERG, 2013h; ERG, 2013i; ERG, 2013l.

Acronyms: MCL (Maximum Contaminant Level); N/A (Not Applicable, no benchmark for comparison); NEHC (No Effect Hazard Concentration); NRWQC 

(National Recommended Water Quality Criteria).

a – The receiving water model included a total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs).

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 

c – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams together in a chemical precipitation plus biological 

treatment system which may result in leachate switching receiving waters to be discharged in the same receiving water as FGD. Under Regulatory Option 5 for 

these plants, leachate is only treated with a chemical precipitation system and is discharged to the original designated receiving water; therefore, due to changes 

in receiving waters between Regulatory Options 4 and 5, the metal loadings at an immediate receiving water level may increase under Regulatory Option 5 

compared to Regulatory Option 4, resulting in the percent reductions of exceedances being lower under Regulatory Option 5.

 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-30 

6.3.4 Cadmium

At baseline conditions, cadmium had the second largest toxic-weighted pollutant 

discharges from the steam electric industry (see Section 3.2). Cadmium is a toxic metal that is 

known to disrupt development in wildlife, resulting in fetal malformations and other effects. 

Studies of steam electric discharges have demonstrated that cadmium and other combustion 

wastewater metals can be lethal to fish and amphibian eggs [Birge, 1978]. In addition, it has been 

linked to impacts on mammals as well. For example, in a study of raccoons living in close 

proximity to a steam electric power plant ash pond, cadmium buildup was found in the raccoons’ 

kidneys at elevated levels [Burger et al., 2002]. EPA determined that the preferred options will 

reduce impacts to both aquatic life and wildlife by decreasing the number of immediate receiving 

waters that exceed acute and chronic NRWQC by up to 27 percent (under Option 3a and 3b), 37 

percent (under Option 3), and 53 percent (under Option 4a). The number of immediate receiving 

waters with fish tissue concentrations that exceed NEHCs for minks and eagles will decrease by 

up to 44 percent (under Options 3a and 3b), 58 percent (under Option 3), and 67 percent (under 

Option 4a). EPA determined that the preferred options will reduce the number of immediate 

receiving waters with intake doses from fish that have the potential to cause non-cancer health 

effects by 36 to 38 percent (under Option 3a), 38 to 42 percent (under Option 3b), 50 to 54 

percent (under Option 3), and 64 to 69 percent (under Option 4a), depending on the cohort. In 

humans, cadmium-related health effects can result from exposure via multiple pathways, with the 

nature and severity of the effects depending on the exposure doses. Table 6-10 presents the key 

environmental improvements as a result of reduced cadmium discharges under the regulatory 

options. 
6-31

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-10. Key Environmental Improvements for Cadmium Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Water Quality Results

Freshwater Acute 

NRWQC

30 10% 23

(23%)

23

(23%)

22

(27%)

22

(27%)

19

(37%)

14

(53%)

5 

(83%)

5 

(83%)

Freshwater Chronic 

NRWQC

65 22% 55

(15%)

54

(17%)

55

(15%)

54

(17%)

51

(22%)

37

(43%)

13

(80%)

13

(80%)

Human Health Water 

and Organism NRWQC

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Human Health 

Organism-only 

NRWQC

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Drinking Water

MCL

22 7% 14

(36%)

14

(36%)

13

(41%)

13

(41%)

10

(55%)

7 

(68%)

3 

(86%)

2 

(91%)

Wildlife Results

Fish Ingestion NEHC 

for Minks

12 4% 9 

(25%)

8 

(33%)

7 

(42%)

7 

(42%)

5 

(58%)

4 

(67%)

2 

(83%)

2 

(83%)

Fish Ingestion NEHC 

for Eagles

9 3% 7 

(22%)

7 

(22%)

5 

(44%)

5 

(44%)

4 

(56%)

3 

(67%)

2 

(78%)

2 

(78%)

Human Health Results—Non-Cancer

Non-cancer reference 

dose for child 

(recreational)

13 4% 9 

(31%)

9 

(31%)

8 

(38%)

8 

(38%)

6 

(54%)

4 

(69%)

2 

(85%)

2 

(85%)

Non-cancer reference 

dose for adult 

(recreational)

13 4% 10

(23%)

10

(23%)

8 

(38%)

8 

(38%)

6 

(54%)

4 

(69%)

2 

(85%)

2 

(85%)
6-32

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-10. Key Environmental Improvements for Cadmium Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Non-cancer reference 

dose for child 

(subsistence)

28 9% 20

(29%)

19

(32%)

18

(36%)

17

(39%)

14

(50%)

10

(64%)

3 

(89%)

3 

(89%)

Non-cancer reference 

dose for adult 

(subsistence)

26 9% 18

(31%)

17

(35%)

16

(38%)

15

(42%)

12

(54%)

9 

(65%)

3 

(88%)

3 

(88%)

Source: ERG, 2013h; ERG, 2013i; ERG, 2013l.

Acronyms: MCL (Maximum Contaminant Level); N/A (Not Applicable, no benchmark for comparison); NEHC (No Effect Hazard Concentration); NRWQC 

(National Recommended Water Quality Criteria).

a – The receiving water model included a total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs).

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-33 

6.3.5 Thallium

Thallium is a toxic metal. As noted in Section 6.2.2, impacts from elevated thallium 

exposures include neurological symptoms (e.g., weakness, sleep disorders, muscular problems), 

alopecia (i.e., loss of hair from the head and body), and gastrointestinal effects (e.g., diarrhea and 

vomiting). Long-term exposures at levels above the MCL may lead to changes in blood 

chemistry; damage to liver, kidney, and intestinal and testicular tissues; and hair loss. Thallium 

exposure can also lead to reproductive and developmental damage [U.S. EPA, 2009a]. EPA 

estimates that the number of immediate receiving waters exceeding human health NRWQC and 

MCLs will reduce by 7 to 13 percent (under Option 3a), 9 to 15 percent (under Option 3b), 11 to 

18 percent (under Option 3), and 38 to 44 percent (under Option 4a). The preferred options will 

also reduce the number of immediate receiving waters with intake doses from fish that have the 

potential to cause non-cancer health effects in humans by 12 to 14 percent (under Options 3a and 

3b), 16 to 18 percent (under Option 3), and 41 to 43 percent (under Option 4a), depending on the 

cohort. Table 6-11 presents the key environmental improvements as a result of reduced thallium 

discharges under the regulatory options. 
6-34

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-11. Key Environmental Improvements for Thallium Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Water Quality Results

Freshwater Acute 

NRWQC

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Freshwater Chronic 

NRWQC

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Human Health Water 

and Organism NRWQC

82 28% 82

(0%)

79

(4%)

71

(13%)

70

(15%)

67

(18%)

46

(44%)

13

(84%)

14

(83%) c

Human Health 

Organism-only 

NRWQC

74 25% 73

(1%)

71

(4%)

65

(12%)

65

(12%)

62

(16%)

43

(42%)

10

(86%)

7 

(91%)

Drinking Water MCL 55 19% 55

(0%)

52

(5%)

51

(7%)

50

(9%)

49

(11%)

34

(38%)

4 

(93%)

4 

(93%)

Wildlife Results

Fish Ingestion NEHC 

for Minks

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Fish Ingestion NEHC 

for Eagles

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Human Health Results—Non-Cancer

Non-cancer reference 

dose for child 

(recreational)

74 25% 73

(1%)

71

(4%)

65

(12%)

65

(12%)

62

(16%)

43

(42%)

10

(86%)

7 

(91%)

Non-cancer reference 

dose for adult 

(recreational)

75 25% 74

(1%)

72

(4%)

66

(12%)

66

(12%)

63

(16%)

44

(41%)

10

(87%)

7 

(91%)
6-35

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-11. Key Environmental Improvements for Thallium Under the Regulatory Options

Evaluation Criteria

Modeled Immediate Receiving 

Waters Exceeding Criteria 

Under Baseline Conditions a

Number of Immediate Receiving Water Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options b

Number Percentage

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Non-cancer reference 

dose for child 

(subsistence)

118 40% 116

(2%)

111

(6%)

102

(14%)

101

(14%)

97

(18%)

67

(43%)

24

(80%)

22

(81%)

Non-cancer reference 

dose for adult 

(subsistence)

109 37% 107

(2%)

104

(5%)

96

(12%)

96

(12%)

92

(16%)

64

(41%)

19

(83%)

18

(83%)

Source: ERG, 2013h; ERG, 2013i; ERG, 2013l.

Acronyms: MCL (Maximum Contaminant Level); N/A (Not Applicable, no benchmark for comparison); NEHC (No Effect Hazard Concentration); NRWQC 

(National Recommended Water Quality Criteria).

a – The receiving water model included a total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs).

b – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 

c – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams together in a chemical precipitation plus biological 

treatment system which may result in leachate switching receiving waters to be discharged in the same receiving water as FGD. Under Regulatory Option 5 for 

these plants, leachate is only treated with a chemical precipitation system and is discharged to the original designated receiving water; therefore, due to changes 

in receiving waters between Regulatory Options 4 and 5, the metal loadings at an immediate receiving water level may increase under Regulatory Option 5 

compared to Regulatory Option 4, resulting in the percent reductions of exceedances being lower under Regulatory Option 5.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-36 

6.4 IMPROVEMENTS TO SENSITIVE ENVIRONMENTS AND WATERSHEDS

As discussed in Sections 3.2 and 3.4, EPA evaluated pollutant discharges to sensitive 

environments (i.e., impaired waters, threatened and endangered species, and fish consumption 

advisory waters) and sensitive watersheds (the Great Lakes and Chesapeake Bay) to assess the 

potential for steam electric power plants to contribute to existing impairments or advisories and 

assess the potential for discharges of the evaluated waste streams to cause increased stress on 

threatened and endangered species. This section presents EPA’s estimated pollutant loading 

reductions under the eight regulatory options to the evaluated sensitive environments. EPA

determined that the proposed ELGs will decrease pollutant loadings to sensitive environments 

which will assist in the recovery of impaired waters; reduce the bioaccumulation of metals in 

fish, thereby reducing the number of fish advisories; and reduce stress on threatened and 

endangered species and sensitive watersheds such as Chesapeake Bay and the Great Lakes.

6.4.1 Impaired Waters

EPA determined that 78 of the steam electric power plants discharge directly into a 

303(d) listed water body designated as impaired for one or more pollutants found in the 

evaluated waste streams. Mercury (52 immediate receiving waters), nutrients (30 immediate 

receiving waters), and phosphorus (16 immediate receiving waters) were the most frequently 

identified impairment categories among the surface waters that directly receive the evaluated 

waste streams. Table 6-12 presents the loading reductions to impaired waters by impairment 

category as a result of the regulatory options. 

Under the preferred options, EPA calculated mercury loadings to waters designated as 

impaired for mercury will be reduced by 31 percent (under Options 3a and 3b), 48 percent (under 

Option 3), and 71 percent (under Option 4a). EPA also calculated that total metal loadings to 

waters designated as impaired for metals other than mercury will be reduced by 19 percent (over 

37,000 pounds) under Option 3a, 29 percent (over 55,000 pounds) under Option 3b, 44 percent 

(over 85,000 pounds) under Option 3, and by 79 percent (152,000 pounds) under Option 4a. 

Phosphorus loadings to water designated as impaired for phosphorus are estimated to reduce by 

almost 17,000 pounds (under Options 3a and 3b), almost 20,000 pounds (under Option 3), and

almost 35,000 pounds (under Option 4a). EPA determined 9 percent (30 immediate receiving 

waters) of surface waters receiving the evaluated waste streams are designated as impaired for 

the general category of nutrients. EPA estimated that the post-compliance pollutant loadings 

under the preferred options will reduce total nitrogen loadings to nutrient-impaired waters by 16 

percent (428,000 pounds) under Options 3a and 3b, 48 percent (1,270,000 pounds) under Option 

3, and 68 percent (1,800,000 pounds) under Option 4a. 
6-37

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-12. Loading Reductions to Impaired Waters by Impairment Type

Impairment 

Type

Number of 

Immediate 

Receiving Waters 

Impaired b

Baseline 

Loadings 

(lbs/yr)

Total Pounds per Year to Impaired Waters Removed Under the Regulatory Options

(Percent Reduction) a

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Arsenic 3 184 0

(0%)

0

(0%)

26.1

(14%)

26.1

(14%)

26.1

(14%)

26.1

(14%)

153

(83%)

153

(83%)

Cadmium 5 317 0

(0%)

2.40

(<1%)

0

(0%)

0

(0%)

2.40

(<1%)

73.1

(23%)

311

(98%)

312

(98%)

Chlorides 3 470,000 0

(0%)

0

(0%)

0

(0%)

0

(0%)

0

(0%)

67.0

(<1%)

313,000

(67%)

313,000

(67%)

Chromium c 4 120 0

(0%)

0

(0%)

0

(0%)

0

(0%)

0

(0%)

35.0

(29%)

90.0

(75%)

90.0

(75%)

Copper 7 1,950 20.8

(1%)

20.8

(1%)

0

(0%)

0

(0%)

20.8

(1%)

795

(41%)

1,830

(94%)

1,830

(94%)

Lead 7 1,330 0.52

(<1%)

0.52

(<1%)

859

(65%)

859

(65%)

859

(65%)

1,000

(75%)

1,260

(95%)

1,260

(95%)

Manganese 5 559,000 456,000

(82%)

523,000

(94%)

19,700

(3.5%)

19,700

(3.5%)

543,000

(97%)

546,000

(98%)

547,000

(98%)

559,000

(100%)

Mercury 52 411 67.1

(16%)

69.3

(17%)

129

(31%)

129

(31%)

198

(48%)

293

(71%)

405

(99%)

406

(99%)

Nutrients d 30 2,650,000 0

(0%)

843,000

(32%)

428,000

(16%)

428,000

(16%)

1,270,000

(48%)

1,800,000

(68%)

2,560,000

(97%)

2,350,000

(89%) e

Phosphorus 16 58,400 0

(0%)

2,000

(3%)

16,100

(28%)

16,100

(28%)

18,100

(31%)

34,700

(59%)

56,800

(97%)

57,400

(98%)

Selenium 3 836 0

(0%)

0

(0%)

791

(95%)

791

(95%)

791

(95%)

791

(95%)

836

(100%)

836

(100%)

TDS 4 14,600,000 0

(0%)

0

(0%)

0

(0%)

0

(0%)

0

(0%)

910,000

(6%)

8,280,000

(57%)

8,280,000

(57%)

Zinc 4 10,600 2,530

(24%)

2,550

(24%)

2,840

(27%)

5,390

(51%)

5,390

(51%)

7,900

(74%)

10,600

(100%)

10,600

(100%)

Source: ERG, 2013e; ERG, 2013g.

a – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 

b – For the impaired waters proximity analysis, EPA evaluated 317 immediate receiving water combinations that receive discharges of the evaluated waste 

streams. 
6-38

Section 6—Environmental Improvements Under the Proposed Regulatory Options

c – The chromium VI loadings are presented with this impairment category. An impairment type is not designated specifically for chromium VI.

d – Total nitrogen loadings are presented with this impairment category. An impairment type is not designated specifically for total nitrogen. 

e– Under Regulatory Option 4 FGD wastewater is treated with chemical precipitation plus biological treatment which removes more nitrogen from the 

wastewater than the evaporation systems; therefore, total nitrogen reductions under Regulatory Option 5 are lower than Regulatory Option 4.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-39 

6.4.2 Threatened and Endangered Species

As discussed in Section 3.4.3, EPA identified 224 threatened and endangered species 

present within surface waters that exceeded NRWQC for the protection of aquatic life under 

baseline conditions. To assess the potential improvements to threatened and endangered species 

under Option 3, EPA evaluated only those species identified as highly vulnerable to changes in 

water quality (127 of the 224 species) and further excluded species from the analysis based on 

criteria such as the species is already presumed extinct, species habitat is unlikely to be affected 

by discharges of the evaluated waste streams (e.g., isolated headwaters), species listing status is 

due to habitat destruction unrelated to steam electric discharges (e.g., damming, stream 

channelization), and other criteria. Based on the analysis, EPA identified 15 species out of the 

127 with a high vulnerability to changes in water quality whose recovery may be enhanced by 

Option 3. EPA determined that eight of the 15 species identified inhabit waters that will no 

longer exceed NRWQC for the protection of aquatic life under Option 3. The species may

therefore experience increases in population growth rates as a result of the proposed ELGs. See 

the Benefits and Cost Analysis for further details on the methodology and results of EPA’s 

threatened and endangered species analysis. EPA did not estimate potential improvements to 

threatened and endangered species under Options 3a, 3b, and 4a. 

6.4.3 Fish Advisory Waters 

States, territories, and authorized tribes issue fish advisories to notify the public 

(including recreational and subsistence fishers) of water bodies containing fish with elevated and 

potentially unhealthy contamination levels. EPA identified mercury as the most common 

pollutant found in combustion wastewater for which fish advisories are issued among the surface 

waters that receive the evaluated waste streams (see Section 3.4.2). EPA determined that 118 of 

the 317 immediate receiving waters included in the EA are under a fish advisory for mercury. 

Under the preferred options, EPA estimates that the number of immediate receiving waters with 

fish that exceed EPA’s mercury screening value will decrease by 15 percent (under Options 3a 

and 3b), 20 percent under Option 3, and 43 percent under Option 4a, thereby reducing the 

potential threat to human health from consuming contaminated fish. 

6.4.4 Sensitive Watersheds: Great Lakes and Chesapeake Bay 

As discussed in Section 3.2, both the Great Lakes and Chesapeake Bay watersheds have a 

history of pollutant discharges that negatively affect water quality, wildlife, and human health. 

Both are well-studied, sensitive environments that are affected by pollutants commonly found in 

combustion wastewater. Discharges of toxic pollutants into these sensitive water bodies by point 

and nonpoint sources are of concern; however, mercury is one of the primary pollutants of 

concern in the Great Lakes,42 and nutrients are the primary pollutants of focus in the Chesapeake 

Bay. 

Mercury is a concern in sensitive watersheds such as the Great Lakes due to its 

bioaccumulation in fish and wildlife and potential impacts on humans. EPA and Environment 

 

42 One of the main environmental pathways for mercury in the Great Lakes is from atmospheric deposition, which is 

not in the scope of the proposed ELGs.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-40 

Canada have documented a range of wildlife impacts from mercury in the Great Lakes, such as 

increased risk of physiological abnormalities in herring gulls [U.S. EPA and Environment 

Canada, 2009]. 

EPA identified 26 steam electric power plants that discharge into the Great Lakes 

watershed. Table 6-13 presents the pollutant loading reductions into the Great Lakes watershed 

under the regulatory options considered by EPA. Under the preferred options, EPA estimated 

that the mercury loadings to the Great Lakes watershed from steam electric power plants will 

reduce by 26 percent (under Options 3a and 3b), 30 percent (under Option 3), and 34 percent 

under Option 4a. Selenium discharges will be reduced by 1,400 pounds per year (22 percent 

reduction) under Options 3a and 3b; 4,450 pounds per year (71 percent reduction) under Option 

3; and 4,530 pounds per year (73 percent reduction) under Option 4a. Total nitrogen loadings 

will decrease by over 125,000 pounds under Options 3a and 3b; 500,000 pounds under Option 3; 

and 635,000 pounds under Option 4a, and total phosphorus loadings decrease by over 5,000 

pounds under Options 3a and 3b; 7,000 pounds under Option 3; and 9,000 pounds under Option 

4a. 

Excessive nutrient loadings to receiving waters significantly affect the ecological stability 

of freshwater and saltwater aquatic systems. Nutrient enrichment of surface waters can stimulate 

excessive plant growth that can obstruct sunlight penetration and increase turbidity, which can 

result in the death of bottom-dwelling aquatic plants. 

EPA identified 20 steam electric power plants that discharge to the Chesapeake Bay 

watershed. Table 6-14 presents the reductions in pollutant loadings to the Chesapeake Bay 

watershed as a result of the regulatory options. EPA estimated that total nitrogen loadings to the 

Chesapeake Bay watershed from steam electric power plants will reduce by 9 percent (218,000 

pounds) under Option 3a, 10 percent (256,000 pounds) under Option 3b, 40 percent (988,000 

pounds) under Option 3, and 86 percent (2,110,000 pounds) under Option 4a. Total phosphorus 

loadings will reduce by 17 percent (10,200 pounds) under Option 3a, 18 percent (10,600 pounds) 

under Option 3b, 22 percent (13,400 pounds) under Option 3, and 84 percent (50,400 pounds) 

under Option 4a. EPA estimated that arsenic and chromium VI discharges to the Chesapeake 

Bay watershed from the evaluated waste streams will be reduced by over 50 percent under 

Options 3a, 3b, and 3 and 80 percent under Option 4a. In addition, EPA estimated that 

manganese and selenium discharges will be reduced by over 80 percent under Option 3 and 90 

under Option 4a. 
6-41

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-13. Total Loadings Removed to the Great Lakes Watershed Under the Regulatory Options

Pollutant

Baseline Total Point 

Source Loadings to 

the Great Lakes 

Watershed

(lbs/yr)

Total Pounds per Year to Great Lakes Watershed Removed Under the Regulatory Options

(Percent Reduction) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Arsenic 4,165 1.98

(<1%)

1.98

(<1%)

1,770

(42%)

1,770

(42%)

1,770

(42%)

1,890

(45%)

4,130

(>99%)

4,140

(>99%)

Boron 1,990,000 0 

(0%)

821,000 

(41%)

180,000

(9%)

180,000

(9%)

1,000,000 

(50%)

1,020,000

(51%)

1,290,000 

(64%)

1,960,000 

(98%)

Cadmium 1,410 91.9

(7%)

99.1

(7%)

266

(19%)

266

(19%)

365

(26%)

416

(30%)

1,390

(99%)

1,390

(99%)

Chromium 

VI

380 0 

(0%)

10.7

(3%)

223

(59%)

223

(59%)

234

(62%)

241

(64%)

366

(96%)

380

(>99%)

Copper 5,180 16.5

(<1%)

16.5

(<1%)

1,690

(33%)

1,690

(33%)

1,700

(33%)

1,880

(36%)

5,160

(>99%)

5,160

(>99%)

Lead 5,840 3.10

(<1%)

3.10

(<1%)

1,210

(21%)

1,210

(21%)

1,210

(21%)

1.440

(25%)

5,830

(>99%)

5,830

(>99%)

Manganese 166,000 67,300

(41%)

132,000 

(80%)

3,440

(2%)

3,440

(2%)

135,000 

(82%)

136,000

(82%)

152,000 

(92%)

163,000

(98%)

Mercury 117 4.57

(4%)

5.16

(4%)

30.0

(26%)

30.0

(26%)

35.2

(30%)

39.5

(34%)

117

(>99%)

117

(>99%)

Nickel 18,300 739

(4%)

755

(4%)

1,390

(8%)

1,390

(8%)

2,150

(12%)

2,950

(16%)

18,300 

(>99%)

18,300 

(>99%)

Nitrogen, 

total

1,990,000 0 

(0%)

442,000 

(22%)

127,000

(6%)

127,000

(6%)

568,000 

(28%)

637,000

(32%)

1,960,000 

(97%)

1,890,000 

(94%) b

Phosphorus, 

total

53,200 0 

(0%)

1,600

(3%)

5,460

(10%)

5,460

(10%)

7,060

(13%)

9,330

(18%)

52,500

(99%)

53,000 

(>99%)

Selenium 6,240 556

(9%)

3,050

(49%)

1,400

(22%)

1,400

(22%)

4,450

(71%)

4,530

(73%)

6,090

(98%)

6,110

(98%)
6-42

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-13. Total Loadings Removed to the Great Lakes Watershed Under the Regulatory Options

Pollutant

Baseline Total Point 

Source Loadings to 

the Great Lakes 

Watershed

(lbs/yr)

Total Pounds per Year to Great Lakes Watershed Removed Under the Regulatory Options

(Percent Reduction) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Thallium 15,900 3.97

(<1%)

41.2

(<1%)

563

(4%)

563

(4%)

604

(4%)

1,360

(9%)

15,900 

(>99%)

15,900 

(>99%)

Zinc 19,800 1,170

(6%)

1,240

(6%)

6,560

(33%)

6,560

(33%)

7,790

(39%)

8,380

(42%)

19,700 

(>99%)

19,600

(>99%) c

Source: ERG, 2013c; ERG, 2013g.

a – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 

b – Under Regulatory Option 4, FGD wastewater is treated with chemical precipitation plus biological treatment which removes more nitrogen from the 

wastewater than the evaporation systems; therefore, total nitrogen reductions under Regulatory Option 5 are lower than Regulatory Option 4.

c – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams together in a chemical precipitation plus biological 

treatment system. Under Regulatory Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for some immediate 

receiving waters the metal loadings will increase under Regulatory Option 5 compared to Regulatory Option 4, resulting in the percent reductions of exceedances 

being lower under Regulatory Option 5. See the Incremental Costs and Pollutant Removals for Proposed Effluent Limitation Guidelines and Standards for the 

Steam Electric Generating Point Source Category Report (DCN SE01957) for further discussion of the regulatory option loadings.
6-43

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-14. Total Loading Reductions to the Chesapeake Bay Watershed Under the Regulatory Options

Pollutant

Baseline Total Point 

Source Loadings to 

the Chesapeake Bay 

Watershed (lbs/yr)

Total Pounds per Year to Chesapeake Bay Watershed Removed Under the Regulatory Options

(Percent Reduction) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Arsenic 5,180 23.7

(<1%)

23.0

(<1%)

2,630

(51%)

2,650

(51%)

2,660

(51%)

4,560

(88%)

5,100

(99%)

5,140

(>99%)

Boron 3,820,000 394,000

(10%)

1,730,000 

(45%)

81,100

(2%)

475,000

(12%)

1,810,000

(47%)

2,050,000

(54%)

2,110,000 

(55%)

3,720,000 

(97%)

Cadmium 1,820 432

(24%)

444

(24%)

312

(17%)

320

(18%)

756

(41%)

1,590

(88%)

1,780

(98%)

1,790

(98%)

Chromium 

VI

681 9.46

(1%)

22.6

(3%)

440

(65%)

450

(66%)

462

(68%)

596

(88%)

653

(96%)

681

(>99%)

Copper 5,150 84.7

(2%)

81.9

(2%)

1,400

(27%)

1,410

(27%)

1,490

(29%)

4,380

(85%)

5,110

(>99%)

5,120

(>99%)

Lead 5,630 17.5

(<1%)

17.5

(<1%)

1,040

(18%)

1,040

(18%)

1,060

(19%)

4,810

(85%)

5,620

(>99%)

5,620

(>99%)

Manganese 519,000 316,000

(61%)

429,000 

(83%)

22,300

(4%)

28,500

(5%)

451,000 

(87%)

466,000

(90%)

485,000 

(93%)

508,000 

(98%)

Mercury 168 21.3

(13%)

22.3

(13%)

47.9

(28%)

48.1

(29%)

70.2

(42%)

142

(85%)

167

(>99%)

168

(>99%)

Nickel 20,700 3,420

(17%)

3,440

(17%)

1,210

(6%)

1,220

(6%)

4,650

(23%)

17,600

(86%)

20,600

(>99%)

20,600

(>99%)

Nitrogen, 

total

2,200,000 38,400

(2%)

770,000

(31%)

218,000

(9%)

256,000

(10%)

988,000 

(40%)

2,110,000

(86%)

2,350,000

(95%)

2,147,000 

(87%) b

Phosphorus, 

total

59,800 363

(<1%)

3,140

(5%)

10,200

(17%)

10,600

(18%)

13,400

(22%)

50,400

(84%)

58,300

(97%)

59,500

(99%)

Selenium 10,100 2,580

(26%)

6,910

(69%)

1,320

(13%)

1,340

(13%)

8,230

(82%)

9,540

(95%)

9,900

(98%)

9,840

(98%) c
6-44

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-14. Total Loading Reductions to the Chesapeake Bay Watershed Under the Regulatory Options

Pollutant

Baseline Total Point 

Source Loadings to 

the Chesapeake Bay 

Watershed (lbs/yr)

Total Pounds per Year to Chesapeake Bay Watershed Removed Under the Regulatory Options

(Percent Reduction) a

Option

1 

Option

2 

Option

3a

Option

3b

Option

3 

Option

4a

Option

4 

Option

5 

Thallium 16,700 24.2

(<1%)

89.0

(<1%)

1,760

(11%)

1,770

(11%)

1,850

(11%)

14,200

(85%)

16,700

(>99%)

16,700

(>99%)

Zinc 21,500 5,380

(25%)

5,510

(26%)

3,590

(17%)

3,600

(17%)

9,090

(42%)

18,700

(87%)

21,400

(>99%)

21,100

(98%) c

Source: ERG, 2013c; ERG, 2013g.

a – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction.

b – Under Regulatory Option 4 FGD wastewater is treated with chemical precipitation plus biological treatment which removes more nitrogen from the 

wastewater than the evaporation systems; therefore, total nitrogen reductions under Regulatory Option 5 are lower than Regulatory Option 4.

c – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams together in a chemical precipitation plus biological 

treatment system. Under Regulatory Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for some immediate 

receiving waters the metal loadings will increase under Regulatory Option 5 compared to Regulatory Option 4, resulting in the percent reductions of exceedances 

being lower under Regulatory Option 5. See the Incremental Costs and Pollutant Removals for Proposed Effluent Limitation Guidelines and Standards for the 

Steam Electric Generating Point Source Category Report (DCN SE01957) for further discussion of the regulatory option loadings.
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-45 

6.5 ENVIRONMENTAL AND HUMAN HEALTH IMPROVEMENTS IN DOWNSTREAM SURFACE 

WATER

EPA estimates that the environmental and human health improvements within the 

immediate receiving waters associated with the regulatory options described above will translate 

into considerable improvements in water quality further downstream from steam electric 

discharges. EPA calculated downstream receiving water concentrations using EPA’s RiskScreening Environmental Indicators (RSEI) model43 and used the wildlife and human health 

models described in Section 4.1.2 to calculate metal concentrations in exposed fish populations 

and human exposure doses from fish consumption in surface waters downstream from steam 

electric discharges for five of the regulatory options (Options 1, 2, 3, 4, and 5). EPA then applied 

adjustment factors to this modeled output to estimate downstream metal concentrations for 

Options 3a, 3b, and 4a. EPA compared downstream receiving water concentrations, fish tissue 

concentrations, and human exposure doses to water quality, wildlife, and non-cancer and cancer 

benchmarks to assess the number of improved river miles associated with the regulatory options. 

Table 6-15 presents the number of downstream river miles exceeding a given water quality, 

wildlife, and human health benchmark for the five regulatory options evaluated in the EA. 

Based on the results of the downstream modeling, EPA determined that downstream river 

miles are impacted by steam electric power plant discharges. Pollutant concentrations continued 

to exceed the NRWQC for human health (water and organism) at 11,200 miles downstream from 

the discharge. EPA estimated that, under the preferred options, up to 3,640 river miles (under 

Option 3a), 3,860 river miles (under Option 3b), 4,830 river miles (under Option 3), and 6,630 

river miles (under Option 4a) downstream from steam electric discharges will no longer exceed 

the human health NRWQC. The preferred options will reduce the number of downstream river 

mile exceedances for each of the NRWQCs and MCLs. This will improve the water quality and 

aquatic habitats available to wildlife and human populations located outside of the immediate 

vicinity of steam electric power plants. In addition, EPA determined that pollutant loading 

reductions under the preferred options will also reduce impacts to wildlife that rely on 

downstream aquatic habitats as a food source. EPA calculates that up to 4,200 river miles (under 

Option 3a), 4,400 river miles (under Option 3b), 5,360 river miles (under Option 3), and 8,180 

river miles (under Option 4a) downstream from steam electric discharges will no longer contain 

fish populations that exceed a NEHC benchmark for minks or eagles. The preferred options will 

also decrease human exposures via fish consumption to pollutants with the potential to cause 

non-cancer health effects in up to 4,100 river miles (under Option 3a), 4,300 river miles (under 

Option 3b), 5,400 downstream river miles (under Option 3), and 8,090 river miles (under Option 

4a). These results demonstrate that steam electric discharges are impacting surface waters 

beyond the initial receiving waters and pollutant loading reductions associated with the preferred 

options will result in substantial environmental and human health improvements for communities 

beyond the area immediately surrounding steam electric power plants. 

 

43 EPA used pollutant loading discharged to each receiving reach by steam electric plant and metal to estimate 

concentrations in downstream reaches. The RSEI model uses a simple dilution and first-order decay equation to 

calculate receiving water concentrations (metals are treated as conservative substances). The RSEI model assumes 

that the plant’s annual discharge is released at a constant rate throughout the year. In addition, EPA included 

pollutant loadings from the Toxic Inventory Release (TRI) database for other industries to represent background 

metal concentrations in the downstream receiving waters. For further details on the on the RSEI model methodology 

and assumptions, see the Benefits and Cost Analysis.
6-46

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-15. Key Environmental Improvements for Downstream Waters Under the Regulatory Options

Evaluation Criteria

Number of River Miles 

Exceeding Criteria Under 

Baseline Conditions

Number of River Miles Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options a

Number of 

Miles

Percentage 

of Total 

Downstream 

Waters 

Evaluated b

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Water Quality Results

Freshwater Acute NRWQC 402 1% 228

(43%)

200

(50%)

212

(47%)

203

(50%)

160

(60%)

114

(72%)

25.7

(94%)

25.7

(94%)

Freshwater Chronic 

NRWQC

1,140 3% 953

(16%)

797

(30%)

793

(30%)

774

(32%)

692

(39%)

495

(57%)

152

(87%)

161

(86%)

Human Health Water and 

Organism NRWQC

11,200 31% 11,100

(<1%)

11,100

(<1%)

7,560

(33%)

7,340

(34%)

6,370

(43%)

4,570

(59%)

854

(92%)

708

(94%)

Human Health Organismonly NRWQC

4,310 12% 4,290

(<1%)

4,280

(<1%)

3,050

(29%)

2,970

(31%)

2,610

(39%)

1,880

(56%)

280

(93%)

215

(95%)

Drinking Water

MCL

965 3% 953

(1%)

924

(4%)

864

(11%)

858

(11%)

836

(13%)

598

(38%)

37.8

(96%)

31.5

(97%)

Wildlife Results

Fish Ingestion NEHC for 

Minks

9,710 27% 7,180

(26%)

7,100

(27%)

5,600

(42%)

5,380

(45%)

4,400

(55%)

3,150

(68%)

475

(95%)

394

(96%)

Fish Ingestion NEHC for 

Eagles

15,300 42% 12,100

(21%)

11,900

(22%)

11,100

(27%)

10,900

(29%)

9,940

(35%)

7,120

(53%)

1,200

(92%)

988

(94%)

Human Health Results—Non-Cancer

Non-cancer reference dose 

for child (recreational)

13,700 38% 10,900

(20%)

10,800

(21%)

9,780

(29%)

9,560

(30%)

8,520

(38%)

6,080

(56%)

1,110

(92%)

934

(93%)

Non-cancer reference dose 

for adult (recreational)

14,800 41% 11,500

(22%)

11,300

(24%)

10,700

(28%)

10,500

(29%)

9,400

(36%)

6,710

(55%)

1,170

(92%)

980

(93%)

Non-cancer reference dose 

for child (subsistence)

23,600 65% 21,400

(9%)

21,000

(11%)

20,300

(14%)

20,100

(15%)

19,200

(19%)

13,700

(42%)

5,540

(77%)

5,050

(79%)

Non-cancer reference dose 

for adult (subsistence)

22,400 62% 20,000

(11%)

19,500

(13%)

18,600

(17%)

18,400

(18%)

17,400

(22%)

12,400

(45%)

4,640

(79%)

4,400

(80%)
6-47

Section 6—Environmental Improvements Under the Proposed Regulatory Options

Table 6-15. Key Environmental Improvements for Downstream Waters Under the Regulatory Options

Evaluation Criteria

Number of River Miles 

Exceeding Criteria Under 

Baseline Conditions

Number of River Miles Exceeding Criteria

(Percent Reduction from Baseline Conditions) Under the Regulatory Options a

Number of 

Miles

Percentage 

of Total 

Downstream 

Waters 

Evaluated b

Option

1

Option

2

Option

3a

Option

3b

Option

3

Option

4a

Option

4

Option

5

Human Health Results—Cancer

Arsenic cancer risk for child 

(recreational)

6.25 <1% 6.25

(0%)

6.25

(0%)

2.00

(65%)

2.00

(68%)

1.36

(78%)

0.99

(84%)

1.36

(78%)

1.36

(78%)

Arsenic cancer risk for adult 

(recreational)

101 <1% 101

(0%)

101

(0%)

53

(48%)

51

(50%)

43.2

(57%)

31

(69%)

5.57

(94%)

5.57

(94%)

Arsenic cancer risk for child 

(subsistence)

68.5 <1% 68.5

(0%)

68.5

(0%)

36

(47%)

35

(49%)

29.9

(56%)

22

(68%)

1.36

(98%)

1.36

(98%)

Arsenic cancer risk for adult 

(subsistence)

266 <1% 197

(26%)

199

(25%)

155

(42%)

150

(44%)

133

(50%)

97

(64%)

18.2

(93%)

13.3

(95%)

Source: ERG, 2013k; ERG, 2013l.

a – >0 to 20 percent reduction; 21 to 40 percent reduction; 41-60 percent reduction; >60 percent reduction. 

b – EPA evaluated a total of 36,200 river miles in the downstream receiving water analysis for metals. Downstream receiving water concentrations are calculated 

until one of three conditions occurs: (1) the discharge has traveled 300 km downstream; (2) the discharge has been traveling downstream for a week; or (3) the 

concentration reaches 1 x 10-9 mg/L. 
Section 6—Environmental Improvements Under the Proposed Regulatory Options

6-48 

6.6 ATTRACTIVE NUISANCES

EPA projects that the pollutant loading reductions associated with the proposed Steam 

Electric ELGs will also decrease the environmental impact to wildlife exposed to pollutants 

through direct contact with surface impoundments and constructed wetlands at steam electric 

power plants. Documented case studies demonstrate that wildlife living near steam electric 

surface impoundments exhibit elevated levels of arsenic, cadmium, chromium, lead, mercury, 

selenium, strontium, and vanadium [Burger et al., 2002; Bryan et al., 2003, Hopkins et al., 1997, 

1998, 2000, 2002, 2006; Nagle et al., 2001, Rattner et al., 2006]. Multiple studies have linked 

attractive nuisance areas at steam electric power plants to diminished reproductive success 

[Hopkins et al., 2002, 2006; Nagle et al., 2001]. EPA estimates that the pollutant loadings 

associated with the preferred options will decrease the exposure of wildlife populations to toxic 

pollutants and reduce the threat combustion residuals surface impoundments pose to surrounding 

wildlife. 

6.7 OTHER SECONDARY IMPROVEMENTS

In addition to the improvements discussed above, other secondary, or ancillary, 

improvements will occur to other resources that are associated directly or indirectly as a result of 

the preferred options. These would include aesthetic and recreational improvements, reduced 

economic impacts such as clean up and treatment costs in response to contamination or 

impoundment failures, reduced injury associated with pond failures, reduced water usage, 

reduced potential for algal blooms and reduced air emissions. EPA did not quantify these 

improvements as part of the EA due to a lack of data from which to do so. 
Section 7—Conclusions

7-1 

SECTION 7

CONCLUSIONS 

Based on evidence in the literature, documented cases studies, and modeled receiving 

water pollutant concentrations, it is clear that current combustion wastewater discharge practices 

at steam electric power plants are impacting the surrounding ecological environments and pose a 

potential human health threat to nearby communities. The U.S. Environmental Protection 

Agency (EPA) estimated that discharges from steam electric power plants contribute at least 50 

to 60 percent of the toxic-weighted pollutant loadings of the combined discharges of all 

industrial categories currently required to report discharges to U.S. waters. These discharges add 

large quantities of toxic bioaccumulative metals (e.g., selenium, arsenic, and mercury) to the 

aquatic environment. Substantial evidence exists that metals from combustion wastewater 

discharges are transferring from the aquatic environment to terrestrial food webs; this indicates 

the potential for broader impacts to ecological systems by altering population diversity and 

community dynamics in the areas surrounding steam electric power plants. Ecosystem recovery 

from exposure to combustion wastewater discharges can be extremely slow and even short 

periods of exposure (e.g., less than a year) can cause observable ecological impacts that last for 

years. The strong bioaccumulative properties and long residence times of pollutants in 

combustion wastewater reinforce the threat of these wastes to the local environment, and many 

of the impacts may not be fully realized for years to come.

In addition, EPA’s modeling demonstrated pollutant loadings from combustion 

wastewater discharges are impacting areas beyond the immediate receiving waters and pose a 

threat to wildlife and human populations in thousands of river miles downstream from steam 

electric power plants under current discharge practices. Furthermore, EPA predicts that the 

recently promulgated Clean Air Act requirements (i.e., Mercury and Air Toxics Standards and 

Cross-State Air Pollution Rule) and other state and local regulations may lead to additional air 

pollution controls (and resulting waste streams) that will increase the pollutant loadings to 

surface waters in the future. EPA determined that these additional pollutant loadings above 

current baseline conditions will increase the number of immediate receiving waters exceeding 

water quality, wildlife, and human health benchmarks in the future.44 

 

44 As part of EPA’s profile of the steam electric industry, EPA established a baseline of January 1, 2014. Therefore, 

to evaluate the impacts of the proposed rule on the industry, EPA used available data to account for changes to the 

industry that are expected to occur by January 1, 2014 (e.g., plant/unit retirements, flue gas desulfurization [FGD] 

system installations). However, EPA recognizes that some recently promulgated Clean Air Act requirements and 

other state and local regulations may lead to additional air pollution controls (and resulting waste streams) at 

existing plants beyond this date. In an effort to confirm that the proposed requirements would be economically 

achievable in such cases, EPA conducted a sensitivity analysis that forecasts future installations of air controls (i.e., 

wet FGD systems) through 202044 and the associated costs of complying with the proposed regulatory requirements 

for the wastewater that may result from the forecasted air control installations. Based on this sensitivity analysis, 

EPA determined that there are additional costs and pollutant loadings associated with these future installations to 

comply with the proposed effluent limitations guidelines and standards (ELGs). Additionally, EPA determined that 

the increase in loadings would result in an increase in environmental exceedances for the baseline conditions. While 

there are some increases in exceedances, some of these new exceedances will also go away under the regulatory 

option scenarios based on the treatment of the FGD wastewater, which also results in increased benefits associated 

with the proposed rule. The details of the sensitivity analysis are described in the ERG memorandum Flue Gas 

Desulfurization Future Profile Sensitivity Analysis (DCN SE01989). 
Section 7—Conclusions

7-2 

Steam electric power plants discharge combustion wastewater into water bodies used for 

recreation, and these discharges can present a potential threat to human health. Documented fish 

kills have resulted in states issuing fish advisories to protect the public from exposure to fish 

with elevated pollutant concentrations in recreational waters that receive combustion wastewater. 

Leachate from combustion residuals surface impoundments and landfills are known to impact 

off-site ground water and drinking water wells at concentrations above maximum contaminant 

level (MCL) drinking water standards and pose a potential threat to human health. 

EPA determined that the preferred options will result in quantifiable improvements in 

ecological and human health by reducing immediate receiving water metal concentrations45 by 

approximately 22 to 36 percent (under Options 3a and 3b), 25 to 48 percent (under Option 3),

and 47 to 60 percent (under Option 4a). The preferred options result in the following 

environmental improvements: 

• 29 percent reduction (Options 3a and 3b), 35 percent reduction (Option 3), or 55 

percent reduction (Option 4a) in the number of immediate receiving waters exceeding 

a National Recommended Water Quality Criteria (NRWQC) for the protection of 

aquatic life;

• 14 percent reduction (Option 3a), 15 percent reduction (Option 3b), 18 percent 

reduction (Option 3), or 41 percent reduction (Option 4a) in the number of immediate 

receiving waters exceeding a NRWQC for the protection of human health; 

• 23 percent reduction (Option 3a), 24 percent reduction (Option 3b), 30 percent 

reduction (Option 3), or 51 percent reduction (Option 4a) in the number of immediate 

receiving waters that support fish that pose a threat to piscivorous wildlife; 

• 40 percent reduction (Option 3a), 60 percent reduction (Options 3b and 3), or 80 

percent reduction (Option 4a) in the number of immediate receiving waters that 

support fish that pose a cancer risk to exposed populations; and 

• 19 percent reduction (Option 3a), 21 percent reduction (Option 3b), 26 percent 

reduction (Option 3), or 47 percent reduction (Option 4a) in the number of immediate 

receiving waters that support fish that pose a potential threat to cause non-cancer 

health effects in exposed populations. 

The analyses presented in the environmental assessment (EA) focus on quantifying the 

environmental improvements within rivers and lakes from post-compliance pollutant loading 

reductions for metals and nutrients. While extensive, the environmental improvements quantified 

above do not encompass the full range of environmental improvements that will result from the 

proposed Steam Electric ELGs. EPA estimated that post-compliance pollutant loading reductions 

will improve wildlife and environmental health by reducing the: 

• Loadings of bioaccumulative metals to the broader ecosystem, reducing long-term 

exposures and sublethal ecological effects;

• Sublethal chronic effects on aquatic life not captured by the NRWQC; 

 

45 Reductions apply to the subset of metals evaluated in the environmental assessment (i.e., arsenic, cadmium, 

chromium VI, copper, lead, mercury, nickel, selenium, thallium, and zinc).
Section 7—Conclusions

7-3 

• Impacts to aquatic and aquatic-dependent wildlife population diversity and 

community structures; and

• Exposure of wildlife to pollutants through direct contact with surface impoundments 

and constructed wetlands at steam electric power plants.

Data limitations prevented EPA from appropriately modeling the scale and complexity of 

the ecosystem processes potentially impacted by combustion wastewater and therefore not fully 

quantifying the improvements listed above. However, documented case studies in the literature 

reinforce that these impacts are common in the environments surrounding steam electric power 

plants and fully support the conclusion that reducing pollutant loadings will improve overall 

environmental and wildlife health. 

Although the EA quantifies impacts to wildlife that consume fish contaminated with 

metals from combustion wastewater, it does not capture the full range of exposure pathways 

through which bioaccumulative metals can enter the surrounding food web. Wildlife can 

encounter bioaccumulative metals from combustion wastewater discharges through direct 

exposure, drinking water, consumption of contaminated vegetation, and consumption of 

contaminated prey other than fish. Therefore, the quantified improvements underestimate the 

complete loadings of bioaccumulative metals that can impact wildlife in the ecosystem. EPA 

estimates that the post-compliance pollutant loading reductions associated with the preferred

options will lower the total amount of bioaccumulative metals entering the food web near steam 

electric power plants. 

EPA estimates that reducing pollutant 

loadings will also lower the occurrence of 

sublethal effects associated with many of the 

pollutants in steam electric wastewater that may 

not be captured by comparisons with NRWQC 

for aquatic life. Well-documented studies 

suggest that organisms in aquatic environments 

near steam electric power plants exhibit chronic 

effects such as changes in metabolic rates, 

decreased growth rates, changes in morphology 

(e.g., fin erosion, oral deformities), and changes 

in behavior (e.g., decreased ability to swim, 

catch prey, or escape from predators) that can 

negatively affect long-term survival [Raimondo 

et al., 1998; Rowe et al., 1996, 2002]. However, 

these effects are not fully quantified in the EA 

due to data limitations, and therefore improvements to wildlife health and survival from the 

proposed ELGs may be underestimated. Reduced organism survival rates from chronic effects 

such as abnormalities can alter interspecies relationships (e.g., declines in the abundance or 

quality of prey) and prolong ecosystem recovery. EPA was unable to quantify changes to aquatic 

and wildlife population diversity and community dynamics; however, population effects (i.e., 

decline in number and type of organisms present) attributed to exposure to combustion 

wastewater are well documented in the literature [Lemly, 1985a; Garrett and Inman, 1984; 

As surface impoundments accumulate fly ash, bottom 

ash and flue gas desulfurization sludges, they can begin 

to fill up and lose their treatment capability.
Section 7—Conclusions

7-4 

Sorensen et al., 1982]. Changes in aquatic populations can alter the structure of aquatic 

communities and cause cascading effects within the food web that result in long-term impacts to 

ecosystem dynamics. EPA estimates that post-compliance pollutant loading reductions 

associated with the proposed ELGs will lower the stressors that can alter population and 

community dynamics and will improve the overall function of ecosystems surrounding steam 

electric power plants. 
Section 8—References

8-1 

SECTION 8

REFERENCES 

AECOM. 2009. Executive Summary: Root Cause Analysis of TVA Kingston Dredge Pond 

Failure on December 22, 2008. Kingston Fossil Plant, Harriman, Tennessee. (June). 

Available online at: http://www.tva.gov/kingston/rca/. DCN SE01944. 

Andersen L.J. and B. Madsen, 1983. Water Science Technology, 15: 207-212 (As cited in Prasad 

et al., 1996). 

ASU. 2009. Appalachian State University. Preliminary Summary Report from Water, Sediment 

and Fish samples collected at the TVA Ash Spill by Appalachian State University, 

Appalachian Voices, Tennessee Aquarium and Wake Forest University. DCN SE01945. 

ATSDR. 1998a. Agency for Toxic Substances and Disease Registry. Health Consultations: 

Martin Creek Lake. Department of Health and Human Services. Atlanta, GA (September).

DCN SE01877. 

ATSDR. 1998b. Health Consultations: Brandy Branch Reservoir. Department of Health and 

Human Services. Atlanta, GA (September). DCN SE01878. 

ATSDR. 1998c. Health Consultations: Welsh Reservoir. Department of Health and Human 

Services. Atlanta, GA (September). DCN SE01880. 

ATSDR. 1999. Mercury Fact Sheet. Department of Health and Human Services. Atlanta, GA.

Available online at: http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=113&tid=24. DCN SE1990. 

ATSDR. 2008a. Cadmium Fact Sheet. Department of Health and Human Services. Atlanta, GA 

(September). DCN SE01898. 

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U.S. EPA. 2007b. Coal Combustion Waste Damage Case Assessments. (July). DCN SE02145. 

U.S. EPA. 2008a. Child-Specific Exposure Factors Handbook. EPA/600/R-06/096F. 

Washington, DC. (September). DCN SE01876. 

U.S. EPA. 2008b. Lake Erie Lakewide Management Plan 2008. DCN SE01940. 

U.S. EPA. 2009a. Toxicological Review of Thallium and Compounds. Integrated Risk 

Information System. EPA/635/R-08/001F. Washington, DC. (September). DCN SE01907. 

U.S. EPA. 2009b. Steam Electric Power Generating Point Source Category: Final Detailed Study 

Report. EPA 821-R-09-008. Washington, DC. (October). DCN SE00003. 

U.S. EPA. 2009c. Technical Support Document for the Preliminary 2010 Effluent Guidelines 

Program Plan. EPA 821-R-09-006. Washington, DC. (October). DCN SE02134. 

U.S. EPA. 2009d. National Recommended Water Quality Criteria. Washington, DC. DCN 

SE01908. 

U.S. EPA. 2009e. National Primary Drinking Water Regulations. EPA 816-F-09-004. 

Washington, DC. (May). DCN SE01909. 

U.S. EPA. 2010a. Provisional Peer-Reviewed Toxicity Values for Thallium and Compounds. 

National Center for Environmental Assessment. Superfund Health Risk Technical Support 

Center, Cincinnati, OH. (September). DCN SE01941. 

U.S. EPA. 2010b. Human and Ecological Risk Assessment of Coal Combustion Wastes (CCW) 

(Draft). Washington, DC. (April). DCN SE01834. 

U.S. EPA. 2010c. Discharge Monitoring Report (DMR) Pollutant Loading Tool: 2010 Data. 

Available online at: http://cfpub.epa.gov/dmr/. DCN SE01959. 
Section 8—References

8-10 

U.S. EPA. 2010d. Chesapeake Bay Total Maximum Daily Load for Nitrogen, Phosphorus and 

Sediment. Washington, DC. (December). DCN SE01910. 

U.S. EPA. 2010e. Final Site Inspection for the Battlefield Golf Club Site, City of Chesapeake, 

Virginia. Washington, DC. (April). DCN SE01948. 

U.S. EPA. 2010f. Federal Register. Vol. 75, No. 118. Hazardous and Solid Waste Management 

System; Identification and Listing of Special Wastes; Disposal of Coal Combustion 

Residuals From Electric Utilities. Washington, DC. (June). DCN SE01953. 

U.S. EPA. 2011a. Technical Factsheet on: THALLIUM. National Primary Drinking Water 

Regulations. Available online at: 

http://water.epa.gov/drink/contaminants/basicinformation/historical/upload/ArchivedTechnical-Fact-Sheet-on-Thallium.pdf. DCN SE01911. 

U.S. EPA. 2011b. Exposure Factors Handbook: 2011 Edition. EPA/600/R-09/052F. Washington, 

DC. (September). DCN SE01912.

U.S. EPA, 2011c. Integrated Risk Information System (IRIS). National Center for Environmental 

Assessment. Washington, DC. Available online at: http://www.epa.gov/IRIS/. DCN 

SE01960. 

U.S. EPA. 2011d. Technical Support Document for the 2010 Effluent Guidelines Program Plan. 

EPA 821-R-09-006. Washington, DC. (October). DCN SE02135. 

U.S. EPA. 2011e. Office of Science & Technology Annual Report, Calendar Year 2011. EPA 

820-R-12-006. Washington, DC. DCN SE01951. 

U.S. EPA. 2011f. Ecological Toxicity Information (website). EPA Region 5. (December). 

Available online at: http://www.epa.gov/R5Super/ecology/toxprofiles.htm. DCN SE01913. 

U.S. EPA. 2012a. “EPA Weighs Setting Possible First-Time Water Quality Criteria for 

Bromide.” Inside EPA. (4 January). DCN SE01949. 

U.S. EPA. 2012b. Final Damage Case Determination Spreadsheet. Washington, DC. (18 

September). DCN SE01966. 

U.S. EPA, 2013a. Steam Electric Technical Questionnaire Database. Washington, DC. DCN 

SE01958. 

U.S. EPA, 2013b. Technical Development Document for the Proposed Effluent Limitations 

Guidelines and Standards for the Steam Electric Power Generating Point Source Category

(EPA-821-R-13-002). Washington, DC. DCN SE01964. 

U.S. EPA. 2013c. Incremental Costs and Pollutant Removals for Proposed Effluent Limitation 

Guidelines and Standards for the Steam Electric Generating Point Source Category Report. 

DCN SE01957. 

U.S. EPA. 2013d. Benefits and Cost Analysis for the Proposed Effluent Limitations Guidelines 

and Standards for the Steam Electric Power Generating Point Source Category (EPA-821-R013-004). Washington, DC. DCN SE03172. 

U.S. EPA. 2013e. Impact Case Study Analysis Database. Washington, DC. DCN SE02156. 

U.S. EPA and Environment Canada. 1997. Great Lakes Binational Toxics Strategy. DCN 

SE01942. 

U.S. EPA and Environment Canada. 2009. State of the Great Lakes 2009. EPA 905-R-09-031. 

DCN SE01939. 
Section 8—References

8-11 

USFWS. 2008. U.S. Fish and Wildlife Service. Steps Taken to Address Selenium Concerns at 

Cane Ridge Wildlife Management Area. News Release (13 June). DCN SE02150. 

USFWS. 2012. Selenium Threat Averted. News Release (19 June). DCN SE01943. 

USGS. 1995. U.S. Geological Survey. Preliminary Compilation of Descriptive

Geoenvironmental Mineral Deposit Models, Chapter 2: Bioavailability of Metals. DCN 

SE01937. 

USGS. 2008. Environmental Contaminants in Freshwater Fish and Their Risk to Piscivorous 

Wildlife Based on a National Monitoring Program. Environ Monit Assess, 152: 469–494. 

DCN SE01893. 

Vengosh, A. 2009. The Tennessee Valley Authority's Kingston Ash Slide: Potential Water 

Quality Impacts of Coal Combustion Waste Storage. A Testimony to the Subcommittee on 

Water Resources and Environment, U.S. House of Representatives. Available online at: 

http://transportation.house.gov/Media/file/water/20090331/Vengosh%20Testimony.pdf. 

DCN SE01864. 

Villanueva, C.M., K.P. Cantor, S. Cordier, J.J.K Jaakkola, W.D. King, D.F. Lynch, S. Porru, and 

M. Kogevinas. 2004. Disinfection Byproducts and Bladder Cancer: A Pooled Analysis. 

Epidemiology, 15(3): 357–367. DCN SE01983. 

WHO. 1976. World Health Organization. Environmental Health Criteria 1: Mercury. 

International Programme on Chemical Safety. Geneva, Switzerland. DCN SE01914. 

WHO. 1987. Environmental Health Criteria 58: Selenium. International Programme on Chemical 

Safety. Geneva, Switzerland. DCN SE01915. 

WHO. 1992. Environmental Health Criteria 135: Cadmium. International Programme on 

Chemical Safety. Geneva, Switzerland. DCN SE01916. 

WHO. 1996. Environmental Health Criteria 182: Thallium. International Programme on 

Chemical Safety. Geneva, Switzerland. DCN SE01917. 

WHO. 1998. Environmental Health Criteria 204: Boron. International Programme on Chemical 

Safety. Geneva, Switzerland. DCN SE01918. 

WHO. 2001. Arsenic in Drinking Water. Available online at: 

<http://www.who.int/mediacentre/factsheets/fs210/en/> (20 January). DCN SE01919. 

WHO. 2009. Bromide in Drinking-Water. Background Document for Development of WHO 

Guidelines for Drinking-Water Quality. WHO/HSE/WSH/09.01/6. Geneva, Switzerland. 

DCN SE01920. 

WHO. 2011. Manganese in Drinking-Water. Background Document for Development of WHO 

Guidelines for Drinking-Water Quality. WHO/HSE/WSH/03.04/104/Rev/1. Geneva, 

Switzerland. DCN SE01921. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix A—Literature Review Methodology and Results 

APPENDIX A 

LITERATURE REVIEW METHODOLOGY AND RESULTS 

This appendix presents the methodology, resources, and summary results for the 

literature review. The U.S. Environmental Protection Agency (EPA) used the keyword list in 

Table A-1 to identify peer-reviewed journal articles that document environmental and human 

health impacts caused by steam electric discharges of the evaluated waste streams. The literature 

search focused on information regarding impacts caused by toxic pollutants1 (e.g., metals such as 

arsenic, lead, mercury, and selenium) in the discharges. EPA also searched for environmental 

assessments, impact studies, and related documents from state and federal governments. 

In addition, the literature search involved collecting information from newspapers, 

environmental groups, industry organizations, and other non-peer-reviewed information sources. 

These sources are considered to be “gray literature” and are not acceptable forms of formal 

documentation of environmental impact events. However, these literature sources can provide 

useful information for identifying potential areas of concern. Often, an environmental event is 

reported in gray literature sources before it is well documented in peer-reviewed journals or 

government reports. EPA used gray literature to help highlight areas of interest and facilitate 

additional searches of peer-reviewed journals for more detailed information on the impacted 

area. 

EPA used several different search engines to broaden the range of reference materials 

represented in the results. The Agency searched the following search engines in the order 

presented, using the keyword list in Table A-1: 

•	 Scirus – A comprehensive science-specific search engine that provides access to a 

large database of scientific, technical, and medical journals; 

•	 Science Direct – An online library that features full text journals from Elsevier, 

Academic Press, and other scholarly publishers; 

•	 Ingenta – A scholarly research database that provides access to a large collection of 

academic and professional research articles; 

•	 Google Scholar – A search engine used to find other articles that cited previously 

identified references as well as perform a general search of scholarly literature, 

including peer-reviewed papers, theses, books, abstracts, and articles from academic 

publishers, professional societies, preprint repositories, and universities and other 

scholarly organizations; and 

•	 Google – A search engine used to perform a general search of information readily 

available on the Internet. 

1 Under the Clean Water Act (CWA), EPA has identified 65 pollutants and classes of pollutants as toxic pollutants, of which 126 

specific substances have been designated priority toxic pollutants. See Appendix A to 40 CFR Part 423 for a list of toxic 

pollutants. 

A-1
 
Appendix A—Literature Review Methodology and Results 

Table A-1. Keyword Search Terms for Environmental Impacts from
 

Steam Electric Power Plants
 

Category Keyword 

Ash pond 

Discharge 

Lake 

Landfill 

Leachate 

Leaks 

Lotic system 

Plume 

Pond 

Power plant 

General Terms Receiving water 

River 

Sediment 

Steam electric 

Stream 

Surface waters 

Water 

Wastewater 

Water pollution 

Water quality 

Waste management 

Wastewater discharges 

Algal blooms 

Attractive nuisance 

Background levels/concentrations 

Bioaccumulation 

Biomagnification 

Biomagnify 

Contamination 

Environmental impact 

Environmental Terms Environmental assessment 

Eutrophication 

Fish 

Fish consumption advisory 

Fish kill 

Fish mortality 

Fish recover y 

Hot Spot 

Toxicity 

Wildlife 

A-2
 
 

Appendix A—Literature Review Methodology and Results 

Table A-1. Keyword Search Terms for Environmental Impacts from
 

Steam Electric Power Plants
 

Category Keyword 

Arsenic 

Arsenate 

Arsenite 

Boron 

Boric Acid 

Chloride(s) 

Chromium 

Magnesium 

Pollutants of Concern Mercury 

Metals 

Methylmercury 

Nitrate 

Nitrogen 

Selenium 

Selenate 

Selenite 

Sulfate 

Coal 

Fuel Source Terms Coal combustion by-products 

Coal combustion residues 

Oil 

Cancer 

Carcinogen 

Carcinogenic 

Human Health Terms Drinking water 

Health effects 

Human health 

Toxicity 

Case study 

Other Terms Damage case assessment 

Environmental impacts 

Environmental aspects 

To perform the literature search, EPA paired each fuel source term (see Table A-1) with 

at least one keyword to focus the search results. Although EPA used multiple fuel source terms, 

the environmental impacts from the steam electric industry are documented most commonly for 

coal-fired power plants. EPA used best professional judgment to create multiple keyword 

combinations to further focus the literature search. 

A-3
 
 

 

 

 

 

 

 

 

Appendix A—Literature Review Methodology and Results 

In addition to the key word combinations and search engines described above, EPA used 

the following supplemental methods to identify more articles for the targeted topic areas: 

•	 Reviewed references cited in previously identified published literature for additional 

documented cases of environmental impact; 

•	 Searched the Agency for Toxic Substances and Disease Registry’s (ATSDR) website 

for public health assessments and health consultations with information on the case 

study sites referenced in Dr. Christopher Rowe’s literature review paper published in 

2002 [Rowe et al., 2002]; 

•	 Searched for case studies of attractive nuisances unrelated to the steam electric 

industry using the search engines described above; 

•	 Reviewed EPA’s September 18, 2012, determination of damage cases primarily 

identified in EPA’s Damage Case Assessment Report; Environmental Integrity 

Project’s (EIP’s) Out of Control: Mounting Damages From Coal Ash; EIP’s In 

Harm’s Way: Lack of Federal Coal Ash Regulations Endangers Americans and Their 

Environment; and Michigan’s Department of Natural Resources and Environment 

(MDNRE’s) Docket Comments (see Table A-3 for a full list of references); and 

•	 Searched magazines related to the steam electric industry and newspapers for articles 

documenting additional environmental impacts. 

EPA created a database for the literature review that documents the identified literature 

and summarizes key information. EPA finalized the primary literature review on November 24, 

2010; however, the database also includes literature identified after the primary search efforts 

were completed. 

The following tables in Appendix A summarize additional results EPA gathered from the 

literature review: 

•	 Table A-2. Summary of Literature Review Results by Information Source; 

•	 Table A-3. Summary of Documented Impacts to Surface Water and Ground Water 

from Steam Electric Power Plant Discharges; 

•	 Table A-4. Summary of Documented Ground Water Damage Cases from Surface 

Impoundments; 

•	 Table A-5. Summary of Documented Ground Water Damage Cases from Landfills; 

•	 Table A-6. Summary of Documented Surface Water Damage Cases from Surface 

Impoundments; 

•	 Table A-7. Summary of Documented Surface Water Damage Cases from Landfills; 

•	 Table A-8. Summary of Attractive Nuisance Case Studies Related to Steam Electric 

Power Plants; 

•	 Table A-9. Summary of Attractive Nuisance Case Studies Unrelated to Steam Electric 

Power Plants; and 

•	 Table A-10. Summary of Selenium Concentrations in the Environment and 

Organisms Experiencing Adverse Effects. 

A-4
 
 

 

 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-2 highlights the results of the literature search, including documents identified 

by keyword searches and relevant documents identified from supplemental methods. Table A-3 

summarizes the number of documented surface water and ground water impact cases identified 

during the literature search and organized by power plant. Table A-4 and Table A-5 summarize 

the documented ground water impact cases from combustion residuals surface impoundments 

and landfills, respectively, identified during the literature search. Table A-6 and Table A-7 

summarize the documented surface water impact cases from combustion residuals surface 

impoundments and landfills, respectively, identified during the literature search. Table A-8 and 

Table A-9 summarize attractive nuisance case studies related and unrelated to steam electric 

power plants, respectively. Table A-10 presents selenium concentrations in the environment that 

are documented in literature as causing sublethal and lethal effects to organisms. 

Table A-2. Summary of Literature Review Results by Information Source 

Source Type 

Number of Documents 

Identified 

Number of Documents 

Reviewed f 

Number of Documents that 

Discussed Environmental 

and Human Health Impacts 

Peer-Reviewed Literature a 151 128 117 

Government Publication b 53 47 32 

University Research c 13 12 9 

Gray Literature d 18 16 14 

Industry Publication e 4 3 3 

Total 239 206 175 

Source: ERG, 2013b.
 

a – Peer-reviewed literature consists of journal articles that undergo a formal review process prior to publishing.
 

b – Government publications are documents affiliated with state or federal government agencies.
 

c – University research includes finalized dissertations and theses, as well as papers published on behalf of a
 

university or presented at a conference.
 

d – Gray literature includes documents that are subjected to a less stringent review process (e.g., newspaper articles,
 

environmental group publications).
 

e – Industry publications include documents prepared by or for industry-affiliated entities.
 

f – Several documents were not reviewed as part of the formal literature review either because EPA was unable to
 

acquire the full text of the document for review or because once the full text document was obtained a preliminary
 

review determined the document was not appropriate for inclusion in the literature review.
 

A-5
 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-3. Summary of Documented Impacts to Surface Water and Ground Water from
 

Steam Electric Power Plant Discharges
 

A-6

Plant Name 

Number of Documented 

Surface Water Case Studies 

and Damage Cases 

Number of Documented 

Ground Water Case Studies 

and Damage Cases 

A.B. Brown Generating Station, Southern Indiana Gas and Electric Company (SIGECO) 

(IN) 0 1b 

Allen Steam Generating Plant, Duke Power (NC) 0 1b 

Alma Station, Dairyland Power (WI) 0 2b 

Asheville Steam Electric Plant, Progress Energy (NC) 0 1b 

B.C. Cobb Power Plant, Consumers Energy (MI)i 0 2c 

Bailly Generating Station, Northern Indiana Public Service Company (NIPSCO) (IN)i 0 2b 

Belews Creek Steam Station, Duke Energy (NC) 13a,b,d 1b 

Belle River Power Plant, Detroit Edison Company (MI)i 1c 1c 

Big Bend Station, Tampa Electric Company (FL) 1b 1b 

Big Cajun 2 Power Plant, NRG Energy/Louisiana Generating, LLC (LA) 0 1b 

Brandon Shores, Constellation Energy (MD)i 0 1d 

Brayton Point Station, Dominion (MA)i 0 1b 

Bruce Mansfield Power Plant, First Energy (PA) 1b 1b 

Bull Run Steam Plant, Tennessee Valley Authority (TVA) (TN) 1b 0 

C.D. McIntosh, Jr. Power Plant, City of Lakeland (FL) 0 1b 

C.R. Huntley Generating Station, NRG Energy (NY)i 0 1b 

Canadys Plant, South Carolina Electric & Gas (SCE&E) (SC) 0 1b 

Cape Fear Steam Plant, Progress Energy (NC) 0 1b 

Cardinal Plant, American Electric Power (AEP) (OH) 1b 1b 

Cayuga Generating Station, Duke Energy (NY)i 1b 1b 

Chesapeake Energy Facility, Dominion Power (VA) 0 1f 

Cholla Steam Electric Generating Station, Arizona Public Service Company (AZ) 0 1b 

Clifty Creek Station, Indiana Kentucky Electric Company (IKEC) (IN) 0 1b 

Clinch River Plant, American Electric Power (AEP)/Appalachian Power (VA) 1b 0 

Coal Creek Station, Cooperative Power Association/United Power (ND) 0 1b 

Coffeen Power Station, Ameren (IL)i 0 1b 

Colbert Fossil Plant, Tennessee Valley Authority (TVA) (AL) 0 1b 

Colstrip Power Plant, PPL Montana (MT) 0 1b 

Columbia Electric Generating Station (WI) 5a 0 

Columbia Energy Center, Alliant Energy (WI) 1b 0 
Appendix A—Literature Review Methodology and Results 

Table A-3. Summary of Documented Impacts to Surface Water and Ground Water from
 

Steam Electric Power Plant Discharges
 

A-7

Plant Name 

Number of Documented 

Surface Water Case Studies 

and Damage Cases 

Number of Documented 

Ground Water Case Studies 

and Damage Cases 

Conesville Power Plant, American Electric Power (AEP) (OH) 0 1b 

Cumberland Steam Plant, Tennessee Valley Authority (TVA) (TN) 0 1b 

Curtis Stanton Energy Center, Orlando Utility Commission (FL) 1b 1b 

Dan River Steam Station, Duke Energy (NC) 0 1b 

Danskammer Generating Station, Dynergy (NY)i 0 1b 

D-Area Coal-Fired Power Plant, Savannah River Site (SRS) (SC) 24a,b 0 

Dave Johnston Power Plant (WY) 0 1b 

Dickerson Generating Station, Mirant (MD) 1f 1g 

Dolet Hills Power Station, Central Louisiana Electric Co-Op (CLECO) Power, LLC (LA) 0 1b 

Duck Creek Station, Central Illinois Light Company (IL) 0 1b 

Dunkirk Generating Station, NRG Energy (NY)i 0 1b 

E.J. Stoneman Generating Station, Dairyland Power Cooperative (WI) 0 1b 

East Bend Generating Station, Cinergy (KY) 0 1b 

Edgewater Generating Station, Alliant Energy (WI)i 0 1b 

Elrama Power Plant, Reliant Energy (PA)i 1b 1b 

Erickson Station, Lansing Board of Water & Light (MI)i 0 1b 

Escanaba Generating Station, Integrys (MI)i 1c 1c 

Fayette Power Project, Lower Colorado River Authority (TX) 1b 1b 

Flint Creek Power Plant, American Electric Power (AEP)/South West Electric Power 

Company (SWEPCO) (AR) 0 1b 

Gallatin Fossil Plant, Tennesee Valley Authority (TVA) (TN) 1b 1b 

General James M. Gavin Power Plant, American Electric Power/Ohio Power Company 

(OH) 1b 1b 

George Neal Station North, Berkshire Hathaway/MidAmerican Energy Company (IA) 0 1b 

George Neal Station South, Berkshire Hathaway/MidAmerican Energy Company (IA) 0 1b 

Gibson Generating Station, Duke Energy (IN) 5a,b 1b 

Glen Lyn Plant, American Electric Power (AEP)/Appalachian Power (VA) 6a,b 0 

Grainger Generating Station, Santee Cooper/South Carolina Public Service Authority 

(SCPSA) (SC) 0 1b 

Harbor Beach Power Plant, Detroit Edison Company (MI)i 1c 1c 

Hatfield's Ferry Power Station, Allegheny Energy (PA) 1b 1b 

Havanna Power Plant, Illinois Power Company (IL) 0 1b 
Appendix A—Literature Review Methodology and Results 

Table A-3. Summary of Documented Impacts to Surface Water and Ground Water from
 

Steam Electric Power Plant Discharges
 

A-8

Plant Name 

Number of Documented 

Surface Water Case Studies 

and Damage Cases 

Number of Documented 

Ground Water Case Studies 

and Damage Cases 

Hennepin Power Station, Illinois Power Company (IL) 0 1b 

Herbert A. Wagner, Constellation Energy (MD)i 0 1d 

Hunlock Power Station, UGI Development Company (PA) 1b 1b 

Hutsonville Power Station, Central Illinois Public Service Company (IL) 0 1b 

Independence Steam Station, Entergy/Arkansas Power and Light (AR) 0 1b 

Indian River Generating Station, NRG Energy (DE) 1b 1b 

J.H. Campbell Power Plant, Consumers Energy (MI) 1c 1c 

J.R. Whiting Generating Plant, CMS/Consumers Energy (MI) 1b 0 

John Amos Plant, American Electric Power (AEP)/Appalachian Power (WV) 1b 0 

John Sevier Fossil Plant, Tennessee Valley Authority (TVA) (TN)i 2b 2b 

Johnsonville Fossil Plant, Tennessee Valley Authority (TVA) (TN) 1b 1b 

Joliet Generating Station 9, Midwest Generation (IL) 0 1b 

Karn/Weadock Generating Facility, Consumer Energy (MI) 1b 1b 

Kingston Fossil Plant, Tennessee Valley Authority (TVA) (TN) 7a,h 1h 

Lansing Smith Plant, Florida Power and Light (FL) 0 1b 

Lee Steam Plant, Progress Energy (NC) 0 1b 

Leland Olds Station, Basin Electric Power Cooperative (ND) 0 1b 

Marion Plant, Southern Illinois Power Cooperative (IL) 1b 1b 

Martin Lake Steam Station, Texas Utilities Electric Service Company (TX) 9a,b 0 

Martin's Creek Power Plant, PPL (PA) 1i 0i 

Marysville Power Plant, Detroit Edison Company (MI)

i 1c 1c 

Merom Generating Station, Hoosier Energy (IN) 0 1b 

Miamiview Landfill, Cincinnati Gas & Electric Company (OH)j 0 1b 

Michigan City Generating Station, Northern Indiana Public Service Company (NIPSCO) 

(IN)i 0 1b 

Mill Creek Plant, E ON U.S./Louisville Gas & Electric (LG&E) (KY) 0 1b 

Mitchell Power Station, Allegheny Energy (PA) 1b 1b 

Montville Generating Station, NRG Energy/Montville Power, LLC (CT) 0 1b 

Morgantown Generating Station (MD) 1 1b 

Muscatine Generating Station, Muscatine Power & Water (IA)i 0 1b 

Muskingum River Plant, American Electric Power (AEP)/ Ohio Power Company (OH) 1b 1b 
Appendix A—Literature Review Methodology and Results 

Table A-3. Summary of Documented Impacts to Surface Water and Ground Water from
 

Steam Electric Power Plant Discharges
 

A-9

Plant Name 

Number of Documented 

Surface Water Case Studies 

and Damage Cases 

Number of Documented 

Ground Water Case Studies 

and Damage Cases 

Nelson Dewey Generating Station, Alliant Energy (WI)i 0 1b 

Northeastern Station, American Electric Power/Public Service Company Oklahoma (OK) 1b 1b 

Oak Creek Power Plant, Wisconsin Energy (WE Energies (WE))/Wisconsin Electric 

Power Company (WI) 0 1b 

Oak Ridge Y-12 Plant, Department of Energy (TN) 4a,b 1b 

Panda Brandywine L.P. (MD)i 1b 1b 

Petersburg Generating Station, Indiana Power & Light (IN) 0 1b 

Phillips Power Plant, Duquesne Light Company (PA) 0 1b 

Pirkey Power Plant, Southwestern Electric Power Company (SWEPCO) (TX) 2a,b 0 

Plant Bowen, Georgia Power (GA) 1b 0 

Port Washington Facility, Wisconsin Electric Power Company (WEPCO) (WI) 0 2b 

Portland Generating Station, RRI Energy (PA) 1b 1b 

Powerton Plant, Commonwealth Edison (IL) 1 1b 

Presque Isle Power Plant, WE Energies (WE) (MI) 0 1c 

Pulliam Power Plant, Wisconsin Public Service Corp. (WI)i 0 1b 

R.M. Heskett Station, Montana-Dakota Utilities (ND) 0 1b 

R.M. Schahfer Generating Station (IN) 0 1b 

Reid Gardner Generating Facility, Nevada Energy (NV) 0 1b 

Riverbend Steam Plant, Duke Energy (NC) 3d 0 

Rock River Generating Station, Alliant Energy (WI)i 0 1b 

Rodemacher Power Station, Central Louisiana Electric Co-Op (CLECO) Power, LLC 

(LA) 1b 1b 

Roxboro Plant, Progress Energy (NC) 7a,b,d 0 

Saint Clair Power Plant, Detroit Edison Company (MI)i 1c 1c 

Salem Harbor Station, Dominion (MA)i 0 1b 

Seminole Generating Station, Seminole Electric Cooperative (FL) 1b 1b 

Seward Generating Station, RRI Energy (PA) 1b 1b 

Shawnee Fossil Plant, Tennessee Valley Authority (TVA) (KY) 1b 1b 

Sheldon Station, Nebraska Public Power District (NE) 0 1b 

Sherburne County (Sherco) Generating Plant, Xcel Energy/Southern Minnesota Municipal 

Power Agency (MN) 1b 1b 
 

 

 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-3. Summary of Documented Impacts to Surface Water and Ground Water from
 

Steam Electric Power Plant Discharges
 

A-10

Plant Name 

Number of Documented 

Surface Water Case Studies 

and Damage Cases 

Number of Documented 

Ground Water Case Studies 

and Damage Cases 

Shiras, Marquette Board of Light & Power (MI)i 0 1c 

Spurlock Station, Eastern Kentucky Power Cooperative (KY) 0 1b 

Sutton Steam Plant, Progress Energy (NC) 0 1b 

Swift Creek Structural Fill, ReUse Technology, Inc./ Full Circle Solutions (NC)j 0 1b 

Urquhart Station, South Carolina Electric & Gas Company (SGE&E) (SC) 0 1b 

Valley Power Plant, Wisconsin Energy (WI)i 0 1b 

Venice Power Station, Union Electric Company/Ameren Energy/AmerenUE (IL) 0 1b 

Vermillion Power Station, Illinois Power (IL) 0 1b 

W.C. Beckjord Station, Duke Energy (formerly Cinergy) (OH) 0 1b 

W.J. Neal Station, Basin Electric Power Cooperative (ND) 1b 1b 

Wateree Station, SCE&G (SC) 0 1b 

Welsh Power Plant, Southwestern Electric Power Company (SWEPCO) (TX) 3a,b 0 

Westover Generating Plant, AES (NY)i 0 1b 

Widows Creek Fossil Plant, Tennessee Valley Authority (TVA) (AL) 0 1b 

Wood River Power Station, Illinois Power Company (IL) 0 1b 

Yorktown Power Station, Virginia Electric Power and Power Company (VEPCO) (VA) 0 1b 

Total 132l 123l 

Source: U.S. EPA, 2012b; U.S. EPA, 2013e. 

a – ERG, 2012b. 

b – U,S. EPA, 2007b; EIP et al., 2010a; EIP et al., 2010b. 

c – MDNRE, 2010. 

d – Ruhl, 2012. 

e – MACo, 2007. 

f – U.S. EPA, 2010e. 

g – Gazette, 2011. 

h – AECOM, 2009; ASU, 2009. 

i – DRBC, 2006. 

j – The damage case source did not specifically identify the plant name; therefore, EPA assumed the plant name based on available literature and proximity of the plant to the 

damage case site. 

k – EPA was unable to identify the steam electric power plant associated with this damage case. For the purpose of counting the unique number of plants, these damages were 

assumed to be associated with a plant not already identified in the damage cases. 

l – One case study or damage case may document impacts to both ground water and surface water. 
 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-11

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Allen Steam Generating Plant, 

Duke Power (NC) 

Bottom Ash, 

Fly Ash 

Arsenic, Manganese, Iron, 

pH, Barium 

X X U.S. EPA, 

2007b 

Asheville Steam Electric Plant, 

Progress Energy (NC) 

Ash Boron, Chromium, Iron, 

Manganese 

X X EIP et al., 

2010a 

Bailly Generating Station, 

Northern Indiana Public Service 

Company (NIPSCO) (IN) 

Ash Arsenic, Lead, Cadmium X U.S. EPA, 

2007b 

Bangor Quarry Ash Disposal 

Site, Portland Generating 

Station, RRI Energy (PA) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Arsenic, Barium, 

Boron, Cadmium, 

Hexavalent Chromium, 

Potassium, pH, Iron, 

Manganese, Sulfate, TDS, 

Aluminum, Fluoride, 

Chlorides 

X X EIP et al., 

2010a 

Belews Creek Steam Station, 

Duke Energy (NC) 

Fly Ash, 

FGD 

Selenium, Mercury, 

Arsenic, Barium, Boron, 

Cadmium, Copper, 

Chromium, Chloride, 

Fluoride, Iron, Lead, 

Manganese, Nitrate, Silver, 

Zinc, Sulfate, TDS, TOH, 

TOC, pH 

X X X X EIP et al., 

2010a 

Big Bend Station, Tampa 

Electric Company (FL) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Arsenic, Aluminum, Boron, 

Chloride, Fluoride, Iron, 

Manganese, Molybdenum, 

Sulfate, Sodium, Thallium, 

Gross Alpha, TDS 

X X X EIP et al., 

2010a 

Big Cajun 2 Power Plant, NRG 

Energy/Louisiana Generating, 

LLC (LA) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, TDS, Calcium X X EIP et al., 

2010b 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-12

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

C.D. McIntosh, Jr. Power Plant, 

City of Lakeland (FL) 

Bottom Ash, 

Fly Ash, 

FGD 

Selenium, Arsenic, 

Cadmium, Lead, 

Manganese, Vanadium, 

Nitrate, Iron, Sulfate, TDS, 

pH 

X EIP et al., 

2010b 

Canadys Plant, South Carolina 

Electric & Gas (SCE&E) (SC) 

Ash Arsenic, Nickel X U.S. EPA, 

2007b 

Cape Fear Steam Plant, Progress 

Energy (NC) 

Ash Lead, Chromium, Boron, 

Iron, Manganese, Sulfate 

X X X EIP et al., 

2010a 

Cardinal Fly Ash Reservoir 

(FAR) 1 and 2, American 

Electric Power (AEP) (OH) 

Bottom Ash, 

Fly Ash, 

FGD 

Arsenic, Boron, 

Molybdenum 

X X X X EIP et al., 

2010b 

Cayuga Coal Ash Disposal 

Landfill, AES (NY) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Arsenic, Boron, 

Cadmium, Lead, TDS, 

Aluminum, Manganese, 

Sulfate 

X X X EIP et al., 

2010b 

Cholla Steam Electric 

Generating Station, Arizona 

Public Service Company (AZ) 

Fly Ash Sulfate, TDS, Chloride, 

Fluoride 

X U.S. EPA, 

2007b 

Clifty Creek Station, Indiana 

Kentucky Electric Company 

(IKEC) (IN) 

Fly Ash, 

Other 

Boron, Manganese, Iron, 

Sulfate 

X X EIP et al., 

2010a 

Coal Creek Station Surface 

Impoundments, Cooperative 

Power Association/United 

Power (ND) 

Ash Selenium, Arsenic, Sulfate, 

Chloride, Boron 

X U.S. EPA, 

2007b 

Colbert Fossil Plant, Tennessee 

Valley Authority (TVA) (AL) 

Ash, Other Selenium, Sulfate, 

Chromium 

X U.S. EPA, 

2007b 

Colstrip Power Plant, PPL 

Montana (MT) 

Bottom Ash, 

Fly Ash, 

FGD 

Selenium, Boron, Sulfate, 

TDS, Molybdenum 

X X EIP et al., 

2010a 
 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-13

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Cumberland Steam Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, 

Aluminum, Boron, 

Chlorides, Iron, Manganese, 

Sulfate, and TDS 

X EIP et al., 

2010b 

Curtis Stanton Energy Center, 

Orlando Utility Commission 

(FL) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Aluminum, Beryllium, 

Calcium, Chloride, Iron, 

Manganese, Sodium, 

Sulfates, TDS, Vanadium, 

Gross Alpha, Radium-226, 

pH 

X EIP et al., 

2010a 

Dan River Steam Station, Duke 

Energy (NC) 

Bottom Ash, 

Fly Ash, 

Other 

Chromium, Iron, Lead, 

Manganese, Silver, Sulfate 

X EIP et al., 

2010b 

Dolet Hills Power Station, 

Central Louisiana Electric CoOp (CLECO) Power, LLC (LA) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Selenium, Arsenic, Lead, 

Chlorides, TDS, Sulfate, 

Iron, pH, Alkalinity, 

Calcium 

X X EIP et al., 

2010b 

Duck Creek Station, Central 

Illinois Light Company (IL) 

Not Specified Sulfate, TDS, Chloride, 

Manganese, Iron 

X U.S. EPA, 

2007b 

E.J. Stoneman Generating 

Station, Dairyland Power 

Cooperative (WI) 

Ash, Other Cadmium, Chromium, 

Sulfate, Manganese, Iron, 

Zinc 

X X U.S. EPA, 

2007b 

Fayette Power Project (Sam 

Seymour), Lower Colorado 

River Authority (TX) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Selenium, Arsenic, 

Aluminum, Chlorides, 

Cobalt, Manganese, 

Molybdenum, Sulfate, TDS 

X X X EIP et al., 

2010b 

Flint Creek Power Plant, 

American Electric Power 

(AEP)/South West Electric 

Power Company (SWEPCO) 

(AR) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Barium, Boron, 

Cadmium, Chromium, Iron, 

Lead, Manganese, pH, 

Silver, Sulfate, TDS 

X X X EIP et al., 

2010b 
 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-14

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Gallatin Fossil Plant, Tennessee 

Valley Authority (TVA) (TN) 

Bottom Ash, 

Fly Ash 

Aluminum, Boron, 

Beryllium, Cadmium, Iron, 

Manganese, Nickel, Sulfate, 

TDS 

X X X X EIP et al., 

2010b 

General James M. Gavin Power 

Plant, American Electric 

Power/Ohio Power Company 

(OH) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Arsenic, Alpha Activity, 

Barium, Cadmium, Lead, 

Molybdenum, Sulfate, TDS, 

Aluminum, Copper, Nickel, 

Zinc 

X X X EIP et al., 

2010b 

Gibson Generating Station, 

Duke Energy (IN) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Boron, 

Manganese, Iron 

X X X EIP et al., 

2010a 

Grainger Generating Station, 

Santee Cooper/South Carolina 

Public Service Authority 

(SCPSA) (SC) 

Fly Ash Arsenic X EIP et al., 

2010a 

Havanna Power Plant, Illinois 

Power Company (IL) 

Ash Manganese, Sulfate X U.S. EPA, 

2007b 

Hennepin Power Station, Illinois 

Power Company (IL) 

Not Specified Sulfate, TDS X U.S. EPA, 

2007b 

Hunlock Power Station, UGI 

Development Company (PA) 

Ash Arsenic, Iron, Manganese, 

Barium, Boron, Lithium 

X X X X EIP et al., 

2010a 

Hutsonville Power Station, 

Central Illinois Public Service 

Company (IL) 

Not Specified Sulfate, TDS X U.S. EPA, 

2007b 

Independence Steam Station, 

Entergy/Arkansas Power and 

Light (AR) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Cadmium, Iron, 

Lead, Manganese, pH, 

Sulfate, TDS, Strontium, 

Boron 

X X EIP et al., 

2010b 

J.H. Campbell, Consumers 

Energy (MI) 

Not Specified Selenium, Boron, Lithium, 

Antimony 

MDNRE, 

2010 

John Sevier Fossil Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Arsenic, Aluminum, 

Cadmium, Manganese, 

Boron, Strontium, Sulfate 

X X X X EIP et al., 

2010a 
 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-15

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Johnsonville Fossil Plant, 

Tennesee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Arsenic, Aluminum, Boron, 

Cadmium, Chromium, 

Chlorides, TDS, Iron, Lead, 

Manganese, Molybdenum, 

Sulfate 

X X EIP et al., 

2010b 

Karn/Weadock Generating 

Facility, Consumer Energy (MI) 

Ash Mercury, Arsenic, Boron, 

Lithium, Phosphorus 

X X EIP et al., 

2010a 

Kingston Fossil Plant, Tennessee 

Valley Authority (TVA) (TN) 

Fly Ash Selenium, Arsenic, Barium, 

Cadmium, Lead 

X X X AECOM, 

2009; ASU, 

2009 

Lansing Smith Plant, Florida 

Power and Light (FL) 

Fly Ash Aluminum, Cadmium, 

Chloride, Chromium, 

Fluoride, Sulfate, 

Manganese, Iron, Radium226, Radium-228, TDS 

X U.S. EPA, 

2007b 

Lee Steam Plant, Progress 

Energy (NC) 

Ash Arsenic, Lead, Boron, 

Manganese, Iron 

X X X EIP et al., 

2010a 

Leland Olds Station Basin 

Electric Power Cooperative 

(ND) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Arsenic, Boron, 

Iron, Lead, Sulfate, TDS 

X EIP et al., 

2010b 

Lincoln Stone Quarry Landfill, 

Joliet Generating Station 9, 

Midwest Generation (IL) 

Bottom Ash, 

Other 

Arsenic, Ammonia, Boron, 

Chlorides, Fluoride, 

Manganese, Molybdenum, 

pH, Sodium, Sulfate, TDS, 

Barium, Copper, Nitrate 

X X X EIP et al., 

2010b 
 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-16

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Little Blue Run Surface 

Impoundment, Bruce Mansfield 

Power Plant, First Energy (PA) 

Bottom Ash, 

Fly Ash, 

FGD 

Selenium, Arsenic, 

Aluminum, Antimony, 

Barium, Boron, Cadmium, 

Calcium, Chloride, 

Hexavalent Chromium, 

Fluoride, Iron, Lead, 

Manganese, pH, Sodium, 

Sulfate, TDS, TSS, 

Thallium, Turbidity 

X X X EIP et al., 

2010b 

Marion Plant, Southern Illinois 

Power Cooperative (IL) 

Bottom Ash, 

Fly Ash, 

FGD 

Boron, Cadmium, Iron, 

Aluminum, Manganese 

X X X X EIP et al., 

2010b 

Michigan City Site (IN) Ash Arsenic X U.S. EPA, 

2007b 

Mill Creek Plant, E ON 

U.S./Louisville Gas & Electric 

(LG&E) (KY) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Arsenic, Chlorides, Sodium, 

Sulfate, TDS 

X X EIP et al., 

2010b 

Mitchell Power Station, 

Allegheny Energy (PA) 

Bottom Ash, 

Fly Ash 

Arsenic, Ammonia, Boron, 

Calcium, Chlorides, Iron, 

Molybdenum, Magnesium, 

Manganese, Nickel, 

Potassium, Sodium, Sulfate, 

Total Alkalinity, TDS 

X X X EIP et al., 

2010a 

Montville Generating Station, 

NRG Energy/Montville Power, 

LLC (CT) 

Bottom Ash, 

Fly Ash 

Arsenic, Beryllium, 

Cadmium, Copper, Iron, 

Lead, Manganese, Nickel, 

pH 

X X X EIP et al., 

2010b 

Morgantown Generating Station, 

Faulkner Off-site Disposal 

Facility (MD) 

Bottom Ash, 

Fly Ash, 

Other 

Iron, pH X X U.S. EPA, 

2007b 

Muskingum River Plant, 

American Electric Power (AEP)/ 

Ohio Power Company (OH) 

Bottom Ash, 

Fly Ash 

Arsenic, Barium, Iron, 

Sulfate 

X X X EIP et al., 

2010b 
 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-17

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Nelson Dewey Ash Disposal 

Facility, Alliant (formerly 

Wisconsin Power & Light) (WI) 

Ash Selenium, Arsenic, Sulfate, 

Boron, Fluoride 

U.S. EPA, 

2007b 

Oak Ridge Y-12 Plant, Chestnut 

Ridge Operable Unit 2, Oak 

Ridge Reservation, Department 

of Energy (TN) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Lead, 

Aluminum, Iron, Barium, 

Cobalt, Magnesium, Zinc, 

Copper, Calcium, 

Manganese, Potassium, 

Thallium, Sodium 

X X U.S. EPA, 

2007b 

Phillips Power Plant Landfill, 

Duquesne Light Company (PA) 

Ash, FGD TDS, Chlorides, Sodium, 

Fluoride, Manganese, 

Aluminum, Sulfate 

X X EIP et al., 

2010a 

Reid Gardner Generating 

Facility, Nevada Energy (NV) 

Fly Ash, 

FGD 

Selenium, Arsenic, 

Chloride, Sulfate, TDS, 

Nitrate, Boron, Chromium, 

Manganese, Magnesium, 

Molybdenum, Sodium, 

Vanadium, Titanium 

X X X EIP et al., 

2010a 

Rodemacher Power Station, 

Central Louisiana Electric CoOp (CLECO) Power, LLC (LA) 

Bottom Ash, 

Fly Ash, 

Other 

Arsenic, Lead, pH, TDS, 

Specific Conductance, 

Chlorides, Sulfate 

X X X EIP et al., 

2010b 

Seminole Generating Station, 

Seminole Electric Cooperative 

(FL) 

Fly Ash, 

FGD, Other 

Arsenic, Chlorides, Sulfates, 

Iron, TDS, Boron, 

Aluminum, Lead, Sodium 

X X X EIP et al., 

2010a 

Seward Generating Station, RRI 

Energy (PA) 

Ash, Other Selenium, Arsenic, 

Aluminum, Antimony , 

Cadmium, Chlorides, 

Chromium, Iron, Lead, 

Manganese, Nickel, pH, 

Sulfate, TDS, Turbidity, 

Zinc, Sodium, Calcium, 

Barium, Boron, Fluoride, 

Magnesium 

X X X EIP et al., 

2010a 
 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-18

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Shawnee Fossil Plant, Tennessee 

Valley Authority (TVA) (KY) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Boron, 

pH, Sulfate, TDS 

X X X EIP et al., 

2010b 

Sherburne County (Sherco) 

Generating Plant, Xcel 

Energy/Southern Minnesota 

Municipal Power Agency (MN) 

Bottom Ash, 

Fly Ash, 

FGD 

Arsenic, Cadmium, 

Chromium, Fluoride, Lead, 

Nitrate, Chloride, Copper, 

Iron, Manganese, Sulfate, 

Zinc 

X X U.S. EPA, 

2007b 

Spurlock Station, Eastern 

Kentucky Power Cooperative 

(KY) 

Bottom Ash, 

Fly Ash, 

FGD 

Arsenic, Sulfate, Iron, TDS X X EIP et al., 

2010b 

Sutton Steam Plant, Progress 

Energy (NC) 

Fly Ash Arsenic, Boron, Manganese, 

Iron 

X X X EIP et al., 

2010a 

Urquhart Station, South Carolina 

Electric & Gas Company 

(SGE&E) (SC) 

Ash Arsenic, Nickel X EIP et al., 

2010a 

Venice Power Station Ash 

Ponds, Union Electric 

Company/Ameren 

Energy/AmerenUE (IL) 

Bottom Ash, 

Fly Ash, 

Other 

Arsenic, Boron, Cadmium, 

Iron, Manganese, TDS 

X X X EIP et al., 

2010b 

Vermillion Power Station, 

Illinois Power (IL) 

Not Specified Sulfate, TDS X X U.S. EPA, 

2007b 

W.C. Beckjord Station, Duke 

Energy (formerly Cinergy) (OH) 

Ash Selenium, Sulfate X X U.S. EPA, 

2007b 

W.J. Neal Station Surface 

Impoundment, Basin Electric 

Power Cooperative (ND) 

Fly Ash, 

FGD, Othe 

Selenium, Arsenic, 

Antimony, Chromium, 

Manganese, Sodium, 

Cadmium, Lead, Zinc 

X U.S. EPA, 

2007b 

Wateree Station, SCE&G (SC) Bottom Ash, 

Fly Ash 

Arsenic X X EIP et al., 

2010a 

Weber Ash Disposal Site, AES 

Creative Resources (NY) 

Ash Sulfate, TDS, Manganese, 

Iron, Aluminum, pH 

X U.S. EPA, 

2007b 
 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-4. Summary of Documented Ground Water Damage Cases from
 

Surface Impoundments
 

A-19

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Westland Disposal Site, 

Dickerson Generating Station, 

Mirant (MD) 

Fly Ash Selenium, Arsenic, Barium, 

Chromium, Cobalt, Copper, 

Iron, Zinc 

X Gazette, 

2011 

Widows Creek Fossil Plant, 

Tennessee Valley Authority 

(TVA) (AL) 

Not Specified Lead, Cadmium, Chromium X U.S. EPA, 

2007b 

Wood River Power Station, 

Illinois Power Company (IL) 

Not Specified Sulfate, TDS, Chloride, 

Manganese, Iron 

X U.S. EPA, 

2007b 

Yorktown Power Station, 

Chisman Creek Disposal Site, 

Virginia Electric Power and 

Power Company (VEPCO) (VA) 

Fly Ash Arsenic, Vanadium, 

Sulfate, Beryllium, 

Chromium, Copper, 

Molybdenum, Nickel, 

Vanadium 

X U.S. EPA, 

2007b 

Acronyms: FGD (Flue Gas Desulfurization); MCL (Maximum Contaminant Level); TDS (Total Dissolved Solids); WQC (Water Quality Criteria).
 

a – This damage case listing is based on a subset of the damage cases that were reviewed by EPA [U.S. EPA, 2012b; U.S. EPA, 2013e].
 

b – The term “ash” was used when the impact case study source did not identify the type of ash present at the waste management unit.
 

c – An “X” indicates that one or more of the pollutants listed exceeded MCLs or federal/state WQC/standards.
 

d – An “X” indicates that the ground water contaminated the surface water with one or more of the pollutants listed.
 

e – An “X” indicates that the ground water contaminated a source outside the plant property boundaries.
 
 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-20

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

A.B. Brown Generating Station, 

Southern Indiana Gas and 

Electric Company (SIGECO) 

(IN) 

Not Specified Sulfate, TDS, Chlorides, pH X U.S. EPA, 

2007b 

Alma Off-Site Fly Ash Landfill, 

Dairyland Power (WI) 

Fly Ash Sulfate, Manganese, Boron U.S. EPA, 

2007b 

Alma On-Site Fly Ash Landfill, 

Dairyland Power (WI) 

Fly Ash Sulfate, Manganese U.S. EPA, 

2007b 

Bangor Quarry Ash Disposal 

Site, Portland Generating 

Station, RRI Energy (PA) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Arsenic, Barium, 

Boron, Cadmium, 

Hexavalent Chromium, 

Potassium, pH, Iron, 

Manganese, Sulfate, TDS, 

Aluminum, Fluoride, 

Chlorides 

X X EIP et al., 

2010a 

Battlefield Golf Club, 

Chesapeake Energy Facility, 

Dominion Power (VA) 

Fly Ash Arsenic X EPA, 2010e 

BBSS Sand and Gravel Quarries, 

Constellation Energy (MD) 

Fly Ash Arsenic, Selenium, 

Aluminum, Cadmium, 

Thallium, Manganese, 

Sulfate 

X MACo, 

2007 

B.C. Cobb, Consumers Energy 

(MI) 

Not Specified Boron , Lithium MDNRE, 

2010 

Belews Creek Steam Station, 

Duke Energy (NC) 

Fly Ash, 

FGD 

Selenium, Mercury, 

Arsenic, Barium, Boron, 

Cadmium, Copper, 

Chromium, Chlorides, 

Fluoride, Iron, Lead, 

Manganese, Nitrate, Silver, 

Zinc, Sulfate, TDS, pH 

X X X X EIP et al., 

2010a 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-21

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Big Bend Station, Tampa 

Electric Company (FL) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Arsenic, Aluminum, Boron, 

Chlorides, Fluoride, Iron, 

Manganese, Molybdenum, 

Sulfate, Sodium, Thallium, 

Gross Alpha, TDS 

X X X EIP et al., 

2010a 

Brandywine Coal Ash Landfill, 

Mirant Mid-Atlantic (LLC) 

Bottom Ash, 

Fly Ash 

Selenium, Cadmium, Lead, 

Manganese, Iron, 

Aluminum, Sulfate, TDS, 

Chlorides 

X X X EIP et al., 

2010a 

C.D. McIntosh, Jr. Power Plant, 

City of Lakeland (FL) 

Bottom Ash, 

Fly Ash, 

FGD 

Selenium, Arsenic, 

Cadmium, Lead, 

Manganese, Vanadium, 

Nitrate, Iron, Sulfate, TDS, 

pH 

X EIP et al., 

2010b 

C.R. Huntley Flyash Landfill 

(NY) 

Fly Ash Arsenic, Iron, Manganese, 

Sulfate, TDS 

X U.S. EPA, 

2007b 

Cardinal Fly Ash Reservoir 

(FAR) 1 and 2, American 

Electric Power (AEP) (OH) 

Bottom Ash, 

Fly Ash, 

FGD 

Arsenic, Boron, 

Molybdenum 

X X X X EIP et al., 

2010b 

Cayuga Coal Ash Disposal 

Landfill, AES (NY) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Arsenic, Boron, 

Cadmium, Lead, TDS, 

Aluminum, Manganese, 

Sulfate 

X X X EIP et al., 

2010b 

CCW Landfill, Trans-Ash, Inc. 

(TN) 

Bottom Ash, 

Fly Ash 

Mercury, Iron, Boron, 

Sulfate 

X X EIP et al., 

2010a 

Cedar-Sauk Landfill, Wisconsin 

Electric Power Company 

(WEPCO) (WI) 

Ash Selenium, Sulfate, Boron X U.S. EPA, 

2007b 

Clifty Creek Station, Indiana 

Kentucky Electric Company 

(IKEC) (IN) 

Fly Ash, 

Other 

Boron, Manganese, Iron, 

Sulfate 

X X EIP et al., 

2010a 
 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-22

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Coal Ash Pit #3, Sheldon 

Station, Nebraska Public Power 

District (NE) 

Bottom Ash, 

Fly Ash 

Selenium, Sulfate X X EIP et al., 

2010b 

Coal Combustion Waste 

Landfill, Merom Generating 

Station, Hoosier Energy (IN) 

Ash Barium, Chromium, 

Cadmium, Lead, Sulfate, 

Chlorides 

X U.S. EPA, 

2007b 

Colstrip Power Plant, PPL 

Montana (MT) 

Bottom Ash, 

Fly Ash, 

FGD 

Selenium, Boron, Sulfate, 

TDS, Molybdenum 

X X EIP et al., 

2010a 

Conesville Fixed FGD Sludge 

Landfill, American Electric 

Power (AEP) (OH) 

Fly Ash, 

FGD 

Arsenic, Cadmium, 

Chromium, Calcium, 

Magnesium, TDS, Sulfate, 

Iron 

X U.S. EPA, 

2007b 

Curtis Stanton Energy Center, 

Orlando Utility Commission 

(FL) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Aluminum, Beryllium, 

Calcium, Chlorides, Iron, 

Manganese, Sodium, 

Sulfate, TDS, Vanadium, 

Gross Alpha, Radium-226, 

pH 

X EIP et al., 

2010a 

Dan River Steam Station, Duke 

Energy (NC) 

Bottom Ash, 

Fly Ash, 

Other 

Chromium, Iron, Lead, 

Manganese, Silver, Sulfate 

X EIP et al., 

2010b 

Danskammer Waste 

Management Facility, Central 

Hudson Gas and Electric 

Corporation (NY) 

Fly Ash Selenium, Arsenic, Sulfate, 

Sulfide, TDS, Turbidity, 

Iron, Magnesium, 

Manganese, Sodium, Boron, 

pH 

X U.S. EPA, 

2007b 

Dave Johnston Power Plant 

(WY) 

Fly Ash Cadmium, Manganese, 

Sulfate, Boron 

X U.S. EPA, 

2007b 

Dolet Hills Power Station, 

Central Louisiana Electric CoOp (CLECO) Power, LLC (LA) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Selenium, Arsenic, Lead, 

Chlorides, TDS, Sulfate, 

Iron, pH, Alkalinity, 

Calcium 

X X EIP et al., 

2010b 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-23

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

East Bend Scrubber Sludge 

Landfill, Cinergy (KY) 

FGD TDS, Iron, Sulfate U.S. EPA, 

2007b 

Edgewater 1-4 Ash Disposal 

Site, Alliant (formerly 

Wisconsin Power & Light) (WI) 

Ash Boron, Sulfate, Iron, 

Chlorides 

X X U.S. EPA, 

2007b 

Fayette Power Project (Sam 

Seymour), Lower Colorado 

River Authority (TX) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Selenium, Arsenic, 

Aluminum, Chlorides, 

Cobalt, Manganese, 

Molybdenum, Sulfate, TDS 

X X X EIP et al., 

2010b 

Fern Valley Landfill, Orion 

Power Holdings, Inc. (a 

subsidiary of RRI Energy) (PA) 

Fly Ash Selenium, Aluminum, 

Boron, Chlorides, Lead, 

Sulfate, TDS 

X X X X EIP et al., 

2010a 

Flint Creek Power Plant, 

American Electric Power 

(AEP)/South West Electric 

Power Company (SWEPCO) 

(AR) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Barium, Boron, 

Cadmium, Chromium, Iron, 

Lead, Manganese, pH, 

Silver, Sulfate, TDS 

X X X EIP et al., 

2010b 

Fly Ash Landfill, Coffeen/ 

White & Brewer Trucking (IL) 

Not Specified Sulfate, TDS, Manganese X U.S. EPA, 

2007b 

Fly Ash Landfill, Don Frame 

Trucking, Inc. (NY) 

Bottom Ash, 

Fly Ash, 

Other 

Lead, Sulfate, TDS, 

Manganese 

X U.S. EPA, 

2007b 

General James M. Gavin Power 

Plant, American Electric 

Power/Ohio Power Company 

(OH) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Arsenic, Alpha Activity, 

Barium, Cadmium, Lead, 

Molybdenum, Sulfate, TDS, 

Aluminum, Copper, Nickel, 

Zinc 

X X X EIP et al., 

2010b 

George Neal Station North 

Landfill, Berkshire 

Hathaway/MidAmerican Energy 

Company (IA) 

Bottom Ash, 

Fly Ash 

Selenium, Iron, Manganese, 

Sulfate 

X X EIP et al., 

2010b 
 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-24

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

George Neal Station South Ash 

Monofill, Berkshire 

Hathaway/MidAmerican Energy 

Company (IA) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Barium, 

Zinc, Iron, Manganese, 

Sulfate 

X X EIP et al., 

2010b 

Gibson Generating Station, 

Duke Energy (IN) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Boron, 

Manganese, Iron 

X X X EIP et al., 

2010a 

Hatfield's Ferry Power Station, 

Allegheny Energy (PA) 

Bottom Ash, 

Fly Ash, 

FGD 

Arsenic, Aluminum, Boron, 

Chromium, Iron, 

Manganese, Molybdenum, 

Thallium, TDS, Sulfate 

X X X EIP et al., 

2010b 

Highway 59 Landfill, Wisconsin 

Electric Power Company 

(WEPCO) (WI) 

Bottom Ash, 

Fly Ash 

Selenium, Sulfate, Boron, 

Manganese, Chlorides, Iron 

X X U.S. EPA, 

2007b 

Independence Steam Station, 

Entergy/Arkansas Power and 

Light (AR) 

Bottom Ash, 

Fly Ash, 

Other 

Selenium, Cadmium, Iron, 

Lead, Manganese, pH, 

Sulfate, TDS, Strontium, 

Boron 

X X EIP et al., 

2010b 

Indian River Generating Station, 

NRG Energy (DE) 

Bottom Ash, 

Fly Ash 

Selenium, Mercury, 

Arsenic, Aluminum, 

Antimony, Barium, 

Cadmium, Chromium, 

Copper, Lead, Nickel, 

Thallium, Vanadium, Zinc, 

Iron, Manganese 

X X X EIP et al., 

2010a 

John Warden Ash Site (MI) Not Specified Boron , Lithium MDNRE, 

2010 

Johnsonville Fossil Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Arsenic, Aluminum, Boron, 

Cadmium, Chromium, 

Chlorides, TDS, Iron, Lead, 

Manganese, Molybdenum, 

Sulfate 

X X EIP et al., 

2010b 
 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-2

5

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

K.R. Rezendes South Main 

Street Ash Landfill, Salem 

Harbor and Brayton Point Plants, 

Pacific Gas and Electric (PG&E) 

(MA) 

Ash Selenium, Sulfate, TDS, 

Manganese, Iron, 

Aluminum 

X U.S. EPA, 

2007b 

Lincoln Stone Quarry Landfill, 

Joliet Generating Station 9, 

Midwest Generation (IL) 

Bottom Ash, 

Other 

Arsenic, Ammonia, Boron, 

Chlorides, Fluoride, 

Manganese, Molybdenum, 

pH, Sodium, Sulfate, TDS, 

Barium, Copper, Nitrate 

X X X EIP et al., 

2010b 

Mahoney Landfill, 

Commonwealth Edison 

Powerton Plant (IL) 

Ash Cadmium, Lead, Nitrate, 

Iron, Manganese, Sulfate 

X U.S. EPA, 

2007b 

Marion Plant, Southern Illinois 

Power Cooperative (IL) 

Bottom Ash, 

Fly Ash, 

FGD 

Boron, Cadmium, Iron, 

Aluminum, Manganese 

X X X X EIP et al., 

2010b 

Miamiview Landfill, Cincinnati 

Gas & Electric Company (OH) 

Not Specified Sulfate X U.S. EPA, 

2007b 

Mill Creek Plant, E ON 

U.S./Louisville Gas & Electric 

(LG&E) (KY) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Arsenic, Chlorides, Sodium, 

Sulfate, TDS 

X X EIP et al., 

2010b 

Mitchell Power Station, 

Allegheny Energy (PA) 

Bottom Ash, 

Fly Ash 

Arsenic, Ammonia, Boron, 

Calcium, Chlorides, Iron, 

Molybdenum, Magnesium, 

Manganese, Nickel, 

Potassium, Sodium, Sulfate, 

Total Alkalinity, TDS 

X X X EIP et al., 

2010a 

Morgantown Generating Station, 

Faulkner Off-Site Disposal 

Facility (MD) 

Bottom Ash, 

Fly Ash, 

Other 

Iron, pH X X U.S. EPA, 

2007b 

Muscatine County Landfill (IA) Ash Selenium, Sulfate, pH, Iron X U.S. EPA, 

2007b 
 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-26

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Muskegon County Type III 

Landfill (MI) 

Not Specified Boron, Manganese MDNRE, 

2010 

North Lansing Landfill, Lansing 

Board of Water & Light (MI) 

Ash, Other Selenium, Boron, Iron, 

Lithium, Manganese, pH 

Potassium, Strontium, 

Sulfate 

U.S. EPA, 

2007b 

Northeastern Station Ash 

Landfill, American Electric 

Power/Public Service Company 

Oklahoma (OK) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Barium, 

Chromium, Lead, 

Vanadium, Thallium, 

Sulfate, pH 

X X X EIP et al., 

2010b 

Oak Creek Power Plant, 

Wisconsin Energy (WE Energies 

(WE))/Wisconsin Electric Power 

Company (WI) 

Bottom Ash, 

Fly Ash, 

FGD, Other 

Mercury, Arsenic, 

Molybdenum, Manganese, 

Sulfate, Boron, Fluoride 

X X EIP et al., 

2010b 

Petersburg Generating Station, 

Indiana Power & Light (IN) 

Not Specified Sulfate, TDS X U.S. EPA, 

2007b 

Phillips Power Plant Landfill, 

Duquesne Light Company (PA) 

Ash, FGD TDS, Chlorides, Sodium, 

Fluoride, Manganese, 

Aluminum, Sulfate 

X X EIP et al., 

2010a 

Pine Hill Landfill, Marquette 

Board of Light & Power (MI) 

Not Specified Boron , Lithium, Sodium MDNRE, 

2010 

Port Washington Facility, 

Wisconsin Electric Power 

Company (WEPCO) (WI) 

Ash Selenium, Boron X U.S. U.S. 

EPA, 2007b 

Presque Isle Power Plant, WE 

Energies (WE) (MI) 

Not Specified Boron , Lithium, Sodium MDNRE, 

2010 

Pulliam Ash Disposal Site, 

Wisconsin Power Supply 

Company (WPSC) (WI) 

Ash Sulfate, Manganese, Iron U.S. EPA, 

2007b 

R.M. Heskett Station, MontanaDakota Utilities (ND) Ash Sulfate, Boron X U.S. EPA, 

2007b 

R.M. Schahfer Generating 

Station (IN) 

Not Specified Sulfate X U.S. EPA, 

2007b 
 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-27

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Range Road Landfill, Detroit 

Edison (MI) 

Ash Boron, Lithium, Sulfate, 

Iron, Manganese 

MDNRE, 

2010 

Reid Gardner Generating 

Facility, Nevada Energy (NV) 

Fly Ash, 

FGD 

Selenium, Arsenic, 

Chlorides, Sulfate, TDS, 

Nitrate, Boron, Chromium, 

Manganese, Magnesium, 

Molybdenum, Sodium, 

Vanadium, Titanium 

X X X EIP et al., 

2010a 

Rock River Ash Disposal 

Facility, Alliant (formerly 

Wisconsin Power & Light) (WI) 

Ash Mercury, Arsenic, Sulfate, 

Iron 

X U.S. EPA, 

2007b 

Rodemacher Power Station, 

Central Louisiana Electric CoOp (CLECO) Power, LLC (LA) 

Bottom Ash, 

Fly Ash, 

Other 

Arsenic, Lead, pH, TDS, 

Specific Conductance, 

Chlorides, Sulfate 

X X X EIP et al., 

2010b 

Seminole Generating Station, 

Seminole Electric Cooperative 

(FL) 

Fly Ash, 

FGD, Other 

Arsenic, Chlorides, Sulfate, 

Iron, TDS, Boron, 

Aluminum, Lead, Sodium 

X X X EIP et al., 

2010a 

Seward Generating Station, RRI 

Energy (PA) 

Ash, Other Selenium, Arsenic, 

Aluminum, Antimony, 

Cadmium, Chlorides, 

Chromium, Iron, Lead, 

Manganese, Nickel, pH, 

Sulfate, TDS, Turbidity, 

Zinc, Sodium, Calcium, 

Barium, Boron, Fluoride, 

Magnesium 

X X X EIP et al., 

2010a 

Shawnee Fossil Plant, Tennessee 

Valley Authority (TVA) (KY) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Boron, 

pH, Sulfate, TDS 

X X X EIP et al., 

2010b 

Spurlock Station, Eastern 

Kentucky Power Cooperative 

(KY) 

Bottom Ash, 

Fly Ash, 

FGD 

Arsenic, Sulfate, Iron, TDS X X EIP et al., 

2010b 
 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-5. Summary of Documented Ground Water Damage Cases 

from Landfills 

A-28

Case Study Site a 

Type of 

Wastes 

Present b Pollutants of Concern 

Exceeded 

MCL c 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Ground 

Water 

Impacted 

Surface 

Waters d 

Impacted 

Off-Site 

Source e Source 

Swift Creek Structural Fill, 

ReUse Technology, Inc./Full 

Circle Solutions (NC) 

Fly Ash Mercury, Arsenic, Barium, 

Lead, Sulfate 

X X X EIP et al., 

2010a 

Urquhart Station, South Carolina 

Electric & Gas Company 

(SGE&E) (SC) 

Ash Arsenic, Nickel X EIP et al., 

2010a 

Weber Ash Disposal Site, AES 

Creative Resources (NY) 

Ash Sulfate, TDS, Manganese, 

Iron, Aluminum, pH 

X U.S. EPA, 

2007b 

Westland Disposal Site, 

Dickerson Generating Station, 

Mirant (MD) 

Fly Ash Selenium, Arsenic, Barium, 

Chromium, Cobalt, Copper, 

Iron, Zinc 

X Gazette, 

2011 

Yard 520 Landfill Site (Brown's 

Landfill), Northern Indiana 

Public Service Company 

(NIPSCO) (IN) 

Fly Ash, 

Other 

Arsenic, Benzene, 

Manganese, Boron, 

Molybdenum, Lead 

X U.S. EPA, 

2007b 

Yorktown Power Station, 

Chisman Creek Disposal Site, 

Virginia Electric Power and 

Power Company (VEPCO) (VA) 

Fly Ash Arsenic, Vanadium, Sulfate, 

Beryllium, Chromium, 

Copper, Molybdenum, 

Nickel, Vanadium 

X U.S. EPA, 

2007b 

Acronyms: FGD (Flue Gas Desulfurization); MCL (Maximum Contaminant Level); TDS (Total Dissolved Solids); WQC (Water Quality Criteria).
 

a – This damage case listing is based on a subset of the damage cases that were reviewed by EPA [U.S. EPA, 2012b; U.S. EPA, 2013e].
 

b – The term “ash” was used when the impact case study source did not identify the type of ash present at the waste management unit.
 

c – An “X” indicates that one or more of the pollutants listed exceeded MCLs or federal/state WQC/standards.
 

d – An “X” indicates that the ground water contaminated the surface water with one or more of the pollutants listed.
 

e – An “X” indicates that the ground water contaminated a source outside the plant property boundaries.
 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-6. Summary of Documented Surface Water Damage Cases 

from Surface Impoundments 

A-29

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact Resulted 

from Ground 

Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Bangor Quarry Ash Disposal 

Site, Portland Generating 

Station, RRI Energy (PA) 

Bottom Ash, 

Fly Ash, Other 

Selenium, Arsenic, 

Barium, Boron, 

Cadmium, Hexavalent 

Chromium, Potassium, 

pH, Iron, Manganese, 

Sulfate, TDS, 

Aluminum, Fluoride, 

Chlorides 

X EIP et al., 

2010a 

Belews Creek Steam Station, 

Duke Energy (NC) 

Fly Ash, FGD Selenium, Mercury, 

Arsenic, Barium, Boron, 

Cadmium, Copper, 

Chromium, Chlorides, 

Fluoride, Iron, Lead, 

Manganese, Nitrate, 

Silver, Zinc, Sulfate, 

TDS, TOH, TOC, pH 

X X X EIP et al., 

2010a 

Big Bend Station, Tampa 

Electric Company (FL) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Arsenic, Aluminum, 

Boron, Chlorides, 

Fluoride, Iron, 

Manganese, 

Molybdenum, Sulfate, 

Sodium, Thallium, Gross 

Alpha, TDS 

X X EIP et al., 

2010a 

Bull Run Steam Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Ash, Other Aluminum, Cadmium, 

Iron, Sulfate 

U.S. U.S. 

EPA, 

2007b 

Cardinal Fly Ash Reservoir 

(FAR) 1 and 2, American 

Electric Power (AEP) (OH) 

Bottom Ash, 

Fly Ash, FGD 

Arsenic, Boron, 

Molybdenum 

X X X EIP et al., 

2010b 

Cayuga Coal Ash Disposal 

Landfill, AES (NY) 

Bottom Ash, 

Fly Ash, Other 

Selenium, Arsenic, 

Boron, Cadmium, Lead, 

TDS, Aluminum, 

Manganese, Sulfate 

X X EIP et al., 

2010b 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-6. Summary of Documented Surface Water Damage Cases 

from Surface Impoundments 

A-30

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact Resulted 

from Ground 

Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Clinch River Plant, American 

Electric Power 

(AEP)/Appalachian Power 

(VA) 

Bottom Ash, 

Fly Ash 

Aluminum, pH X EIP et al., 

2010b 

Columbia Energy Center, 

Alliant Energy (WI) 

Bottom Ash, 

Fly Ash 

Cadmium, Copper, 

Barium, Aluminum, 

Iron, Zinc 

X EIP et al., 

2010b 

Curtis Stanton Energy Center, 

Orlando Utility Commission 

(FL) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Aluminum, Beryllium, 

Calcium, Chlorides, 

Iron, Manganese, 

Sodium, Sulfate, TDS, 

Vanadium, Gross Alpha, 

Radium-226, pH 

X EIP et al., 

2010a 

Fayette Power Project (Sam 

Seymour), Lower Colorado 

River Authority (TX) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Selenium, Arsenic, 

Aluminum, Chlorides, 

Cobalt, Manganese, 

Molybdenum, Sulfate, 

TDS 

X X EIP et al., 

2010b 

Gallatin Fossil Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Aluminum, Boron, 

Beryllium, Cadmium, 

Iron, Manganese, Nickel, 

Sulfate, TDS 

X X X EIP et al., 

2010b 

General James M. Gavin 

Power Plant, American 

Electric Power/Ohio Power 

Company (OH) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Arsenic, Alpha Activity, 

Barium, Cadmium, 

Lead, Molybdenum, 

Sulfate, TDS, 

Aluminum, Copper, 

Nickel, Zinc 

X X EIP et al., 

2010b 

Gibson Generating Station, 

Duke Energy (IN) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, 

Boron, Manganese, Iron 

X X EIP et al., 

2010a 

Glen Lyn Plant, American 

Electric Power 

(AEP)/Appalachian Power 

(VA) 

Bottom Ash, 

Fly Ash 

Selenium, Cadmium, 

Copper, Chromium, 

Zinc, pH, TSS 

X X EIP et al., 

2010b 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-6. Summary of Documented Surface Water Damage Cases 

from Surface Impoundments 

A-31

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact Resulted 

from Ground 

Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Hunlock Power Station, UGI 

Development Company (PA) 

Ash Arsenic, Iron, 

Manganese, Barium, 

Boron, Lithium 

X X X EIP et al., 

2010a 

J.H. Campbell, Consumers 

Energy (MI) 

Not Specified Selenium, Boron, 

Lithium, Antimony 

MDNRE, 

2010 

J.R. Whiting Generating Plant, 

CMS/Consumers Energy (MI) 

Fly Ash, Other Selenium, Arsenic, 

Cobalt, Possibly Nickel 

X EIP et al., 

2010b 

John Sevier Fossil Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Arsenic, Aluminum, 

Cadmium, Manganese, 

Boron, Strontium, 

Sulfate 

X X X EIP et al., 

2010a 

Johnsonville Fossil Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Arsenic, Aluminum, 

Boron, Cadmium, 

Chromium, Chlorides, 

TDS, Iron, Lead, 

Manganese, 

Molybdenum, Sulfate 

X EIP et al., 

2010b 

Karn/Weadock Generating 

Facility, Consumer Energy 

(MI) 

Ash Mercury, Arsenic, 

Boron, Lithium, 

Phosphorus 

X EIP et al., 

2010a 

Kingston Fossil Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Fly Ash Arsenic, Selenium, 

Barium, Cadmium, Lead 

X X X AECOM, 

2009; 

ASU, 

2009 

Little Blue Run Surface 

Impoundment, Bruce 

Mansfield Power Plant, First 

Energy (PA) 

Bottom Ash, 

Fly Ash, FGD 

Selenium, Arsenic, 

Aluminum, Antimony, 

Barium, Boron, 

Cadmium, Calcium, 

Chlorides, Hexavalent 

Chromium, Fluoride, 

Iron, Lead, Manganese, 

pH, Sodium, Sulfate, 

TDS, TSS, Thallium, 

Turbidity 

X X EIP et al., 

2010b 
 

Appendix A—Literature Review Methodology and Results 

Table A-6. Summary of Documented Surface Water Damage Cases 

from Surface Impoundments 

A-32

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact Resulted 

from Ground 

Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Little Scary Creek Fly Ash 

Impoundment, John Amos 

Plant, American Electric 

Power (AEP)/Appalachian 

Power (WV) 

Bottom Ash, 

Fly Ash 

Selenium X X X EIP et al., 

2010a 

Marion Plant, Southern 

Illinois Power Cooperative 

(IL) 

Bottom Ash, 

Fly Ash, FGD 

Boron, Cadmium, Iron, 

Aluminum, Manganese 

X X X EIP et al., 

2010b 

Martin's Creek Power Plant, 

PPL (PA) 

Fly Ash Arsenic, Selenium, 

Mercury, Lead, 

Aluminum, Manganese, 

Copper 

X X DRBC, 

2006 

Mitchell Power Station, 

Allegheny Energy (PA) 

Bottom Ash, 

Fly Ash 

Arsenic, Ammonia, 

Boron, Calcium, 

Chlorides, Iron, 

Molybdenum, 

Magnesium, Manganese, 

Nickel, Potassium, 

Sodium, Sulfate, Total 

Alkalinity, TDS 

X X EIP et al., 

2010a 

Morgantown Generating 

Station, Faulkner Off-Site 

Disposal Facility (MD) 

Bottom Ash, 

Fly Ash, Other 

Iron, pH X X U.S. U.S. 

EPA, 

2007b 

Muskingum River Plant, 

American Electric Power 

(AEP)/ Ohio Power Company 

(OH) 

Bottom Ash, 

Fly Ash 

Arsenic, Barium, Iron, 

Sulfate 

X X EIP et al., 

2010b 

Oak Ridge Y-12 Plant, 

Chestnut Ridge Operable Unit 

2, Oak Ridge Reservation, 

Department of Energy (TN) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, Lead, 

Aluminum, Iron, 

Barium, Cobalt, 

Magnesium, Zinc, 

Copper, Calcium, 

Manganese, Potassium, 

Thallium, Sodium 

X U.S. U.S. 

EPA, 

2007b 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-6. Summary of Documented Surface Water Damage Cases 

from Surface Impoundments 

A-33

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact Resulted 

from Ground 

Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Plant Bowen, Georgia Power 

(GA) 

Bottom Ash, 

Fly Ash, Other 

Not Specified U.S. U.S. 

EPA, 

2007b 

Rodemacher Power Station, 

Central Louisiana Electric CoOp (CLECO) Power, LLC 

(LA) 

Bottom Ash, 

Fly Ash, Other 

Arsenic, Lead, pH, TDS, 

Specific Conductance, 

Chlorides, Sulfate 

X X EIP et al., 

2010b 

Savannah River Site, D-Area, 

Department of Energy (SC) 

Fly Ash Not Specified U.S. EPA, 

2007b 

Seminole Generating Station, 

Seminole Electric Cooperative 

(FL) 

Fly Ash, FGD, 

Other 

Arsenic, Chlorides, 

Sulfate, Iron, TDS, 

Boron, Aluminum, Lead, 

Sodium 

X X EIP et al., 

2010a 

Seward Generating Station, 

RRI Energy (PA) 

Ash, Other Selenium, Arsenic, 

Aluminum, Antimony, 

Cadmium, Chlorides, 

Chromium, Iron, Lead, 

Manganese, Nickel, pH, 

Sulfate, TDS, Turbidity, 

Zinc, Sodium, Calcium, 

Barium, Boron, Fluoride, 

Magnesium 

X X EIP et al., 

2010a 

Shawnee Fossil Plant, 

Tennessee Valley Authority 

(TVA) (KY) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, 

Boron, pH, Sulfate, TDS 

X X EIP et al., 

2010b 

Sherburne County (Sherco) 

Generating Plant, Xcel 

Energy/Southern Minnesota 

Municipal Power Agency 

(MN) 

Bottom Ash, 

Fly Ash, FGD 

Arsenic, Cadmium, 

Chromium, Fluoride, 

Lead, Nitrate, Chlorides, 

Copper, Iron, 

Manganese, Sulfate, 

Zinc 

X U.S. U.S. 

EPA, 

2007b 
 

 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-6. Summary of Documented Surface Water Damage Cases 

from Surface Impoundments 

A-34

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact Resulted 

from Ground 

Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

W.J. Neal Station Surface 

Impoundment, Basin Electric 

Power Cooperative (ND) 

Fly Ash, FGD, 

Other 

Selenium, Arsenic, 

Antimony, Chromium, 

Manganese, Sodium, 

Cadmium, Lead, Zinc 

X U.S. U.S. 

EPA, 

2007b 

Westland Disposal Site, 

Dickerson Generating Station, 

Mirant (MD) 

Fly Ash Selenium, Arsenic, 

Barium, Chromium, 

Cobalt, Copper, Iron, 

Zinc 

X Gazette, 

2011 

Acronyms: FGD (Flue Gas Desulfurization); TDS (Total Dissolved Solids); TOC (Total Organic Carbon); TOH (Total Organic Hydrocarbons); TSS (Total 

Suspended Solids); WQC (Water Quality Criteria).
 

a – This damage case listing is based on a subset of the damage cases that were reviewed by EPA [U.S. EPA, 2012b; U.S. EPA, 2013e].
 

b – The term “ash” was used when the impact case study source did not identify the type of ash present at the waste management unit.
 

c – An “X” indicates that one or more of the pollutants listed exceeded federal/state WQC/standards.
 

d – An “X” indicates that the contaminated surface water was issued a fish consumption advisory.
 

e – An “X” indicates that the ground water contaminated the surface water with one or more of the pollutants listed.
 

f – An “X” indicates that the surface water contaminated a source outside the plant property boundaries.
 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-7. Summary of Documented Surface Water Damage Cases 

from Landfills 

A-35

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact 

Resulted from 

Ground Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Bangor Quarry Ash Disposal 

Site, Portland Generating 

Station, RRI Energy (PA) 

Bottom Ash, 

Fly Ash, Other 

Selenium, Arsenic, 

Barium, Boron, 

Cadmium, Hexavalent 

Chromium, Potassium, 

pH, Iron, Manganese, 

Sulfate, TDS, 

Aluminum, Fluoride, 

Chlorides 

X EIP et al., 

2010a 

Belews Creek Steam Station, 

Duke Energy (NC) 

Fly Ash, FGD Selenium, Mercury, 

Arsenic, Barium, Boron, 

Cadmium, Copper, 

Chromium, Chlorides, 

Fluoride, Iron, Lead, 

Manganese, Nitrate, 

Silver, Zinc, Sulfate, 

TDS, TOH, TOC, pH 

X X X EIP et al., 

2010a 

Big Bend Station, Tampa 

Electric Company (FL) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Arsenic, Aluminum, 

Boron, Chlorides, 

Fluoride, Iron, 

Manganese, 

Molybdenum, Sulfate, 

Sodium, Thallium, Gross 

Alpha, TDS 

X X EIP et al., 

2010a 

Brandywine Coal Ash Landfill, 

Mirant Mid-Atlantic (LLC) 

Bottom Ash, 

Fly Ash 

Selenium, Cadmium, 

Lead, Manganese, Iron, 

Aluminum, Sulfate, 

TDS, Chlorides 

X X EIP et al., 

2010a 

Cardinal Fly Ash Reservoir 

(FAR) 1 and 2, American 

Electric Power (AEP) (OH) 

Bottom Ash, 

Fly Ash, FGD 

Arsenic, Boron, 

Molybdenum 

X X X EIP et al., 

2010b 

Cayuga Coal Ash Disposal 

Landfill, AES (NY) 

Bottom Ash, 

Fly Ash, Other 

Selenium, Arsenic, 

Boron, Cadmium, Lead, 

TDS, Aluminum, 

Manganese, Sulfate 

X X EIP et al., 

2010b 
 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-7. Summary of Documented Surface Water Damage Cases 

from Landfills 

A-36

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact 

Resulted from 

Ground Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

CCW Landfill, Trans-Ash, Inc. 

(TN) 

Bottom Ash, 

Fly Ash 

Mercury, Iron, Boron, 

Sulfate 

X EIP et al., 

2010a 

Columbia Energy Center, 

Alliant Energy (WI) 

Bottom Ash, 

Fly Ash 

Cadmium, Copper, 

Barium, Aluminum, 

Iron, Zinc 

X EIP et al., 

2010b 

Curtis Stanton Energy Center, 

Orlando Utility Commission 

(FL) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Aluminum, Beryllium, 

Calcium, Chlorides, 

Iron, Manganese, 

Sodium, Sulfate, TDS, 

Vanadium, Gross Alpha, 

Radium-226, pH 

X EIP et al., 

2010a 

Fayette Power Project (Sam 

Seymour), Lower Colorado 

River Authority (TX) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Selenium, Arsenic, 

Aluminum, Chlorides, 

Cobalt, Manganese, 

Molybdenum, Sulfate, 

TDS 

X X EIP et al., 

2010b 

Fern Valley Landfill, Orion 

Power Holdings, Inc. (a 

subsidiary of RRI Energy) 

(PA) 

Fly Ash Selenium, Aluminum, 

Boron, Chlorides, Lead, 

Sulfate, TDS 

X X X EIP et al., 

2010a 

General James M. Gavin 

Power Plant, American 

Electric Power/Ohio Power 

Company (OH) 

Bottom Ash, 

Fly Ash, FGD, 

Other 

Arsenic, Alpha Activity, 

Barium, Cadmium, 

Lead, Molybdenum, 

Sulfate, TDS, 

Aluminum, Copper, 

Nickel, Zinc 

X X EIP et al., 

2010b 

Gibson Generating Station, 

Duke Energy (IN) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, 

Boron, Manganese, Iron 

X X EIP et al., 

2010a 

Hatfield's Ferry Power Station, 

Allegheny Energy (PA) 

Bottom Ash, 

Fly Ash, FGD 

Arsenic, Aluminum, 

Boron, Chromium, Iron, 

Manganese, 

Molybdenum, Thallium, 

TDS, Sulfate 

X X EIP et al., 

2010b 
 

Appendix A—Literature Review Methodology and Results 

Table A-7. Summary of Documented Surface Water Damage Cases 

from Landfills 

A-37

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact 

Resulted from 

Ground Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Indian River Generating 

Station, NRG Energy (DE) 

Bottom Ash, 

Fly Ash 

Selenium, Mercury, 

Arsenic, Aluminum, 

Antimony, Barium, 

Cadmium, Chromium, 

Copper, Lead, Nickel, 

Thallium, Vanadium, 

Zinc, Iron, Manganese 

X X EIP et al., 

2010a 

John Warden Ash Site (MI) Not Specified Boron , Lithium MDNRE, 

2010 

Johnsonville Fossil Plant, 

Tennessee Valley Authority 

(TVA) (TN) 

Bottom Ash, 

Fly Ash 

Arsenic, Aluminum, 

Boron, Cadmium, 

Chromium, Chlorides, 

TDS, Iron, Lead, 

Manganese, 

Molybdenum, Sulfate 

X EIP et al., 

2010b 

Little Scary Creek Fly Ash 

Impoundment, John Amos 

Plant, American Electric 

Power (AEP)/Appalachian 

Power (WV) 

Bottom Ash, 

Fly Ash 

Selenium X X X EIP et al., 

2010a 

Mahoney Landfill, 

Commonwealth Edison 

Powerton Plant (IL) 

Ash Cadmium, Lead, Nitrate, 

Iron, Manganese, Sulfate 

U.S. U.S. 

EPA, 

2007b 

Marion Plant, Southern Illinois 

Power Cooperative (IL) 

Bottom Ash, 

Fly Ash, FGD 

Boron, Cadmium, Iron, 

Aluminum, Manganese 

X X X EIP et al., 

2010b 

Mitchell Power Station, 

Allegheny Energy (PA) 

Bottom Ash, 

Fly Ash 

Arsenic, Ammonia, 

Boron, Calcium, COD, 

Chlorides, Iron, 

Molybdenum, 

Magnesium, Manganese, 

Nickel, Potassium, 

Sodium, Sulfate, Total 

Alkalinity, TDS 

X X EIP et al., 

2010a 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-7. Summary of Documented Surface Water Damage Cases 

from Landfills 

A-38

Case Study Site a 

Type of Wastes 

Present b Pollutants of Concern 

Exceeded 

Federal/ 

State WQC/ 

Standards c 

Issued a Fish 

Consumption 

Advisory d 

Impact 

Resulted from 

Ground Water 

Contamination e 

Impacted 

Off-Site 

Source f Source 

Morgantown Generating 

Station, Faulkner Off-Site 

Disposal Facility (MD) 

Bottom Ash, 

Fly Ash, Other 

Iron, pH X X U.S. EPA, 

2007b 

Northeastern Station Ash 

Landfill, American Electric 

Power/Public Service 

Company Oklahoma (OK) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, 

Barium, Chromium, 

Lead, Vanadium, 

Thallium, Sulfate, pH 

X X EIP et al., 

2010b 

Range Road Landfill, Detroit 

Edison (MI) 

Ash Boron, Lithium, Sulfate, 

Iron, Manganese 

MDNRE, 

2010 

Rodemacher Power Station, 

Central Louisiana Electric CoOp (CLECO) Power, LLC 

(LA) 

Bottom Ash, 

Fly Ash, Other 

Arsenic, Lead, pH, TDS, 

Specific Conductance, 

Chlorides, Sulfate 

X X EIP et al., 

2010b 

Seminole Generating Station, 

Seminole Electric Cooperative 

(FL) 

Fly Ash, FGD, 

Other 

Arsenic, Chlorides, 

Sulfate, Iron, TDS, 

Boron, Aluminum, Lead, 

Sodium 

X X EIP et al., 

2010a 

Seward Generating Station, 

RRI Energy (PA) 

Ash, Other Selenium, Arsenic, 

Aluminum, Antimony, 

Cadmium, Chlorides, 

Chromium, Iron, Lead, 

Manganese, Nickel, pH, 

Sulfate, TDS, Turbidity, 

Zinc, Sodium, Calcium, 

Barium, Boron, Fluoride, 

Magnesium 

X X EIP et al., 

2010a 

Shawnee Fossil Plant, 

Tennessee Valley Authority 

(TVA) (KY) 

Bottom Ash, 

Fly Ash 

Selenium, Arsenic, 

Boron, pH, Sulfate, TDS 

X X EIP et al., 

2010b 

Westland Disposal Site, 

Dickerson Generating Station, 

Mirant (MD) 

Fly Ash Selenium, Arsenic, 

Barium, Chromium, 

Cobalt, Copper, Iron, 

Zinc 

X Gazette, 

2011 
 

 

 

Appendix A—Literature Review Methodology and Results 

Acronyms: COD (Chemical Oxygen Demand); FGD (Flue Gas Desulfurization); TDS (Total Dissolved Solids); TOC (Total Organic Carbon); TOH (Total 

Organic Hydrocarbons); TSS (Total Suspended Solids); WQC (Water Quality Criteria).
 

a – This damage case listing is based on a subset of the damage cases that were reviewed by EPA [U.S. EPA, 2012b; U.S. EPA, 2013e].
 

b – The term “ash” was used when the impact case study source did not identify the type of ash present at the waste management unit.
 

c – An “X” indicates that one or more of the pollutants listed exceeded federal/state WQC/standards.
 

d – An “X” indicates that the contaminated surface water was issued a fish consumption advisory.
 

e – An “X” indicates that the ground water contaminated the surface water with one or more of the pollutants listed.
 

f – An “X” indicates that the surface water contaminated a source outside the plant property boundaries.
 

A-39
 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-8. Summary of Attractive Nuisance Case Studies Related to Steam Electric Power Plants 

A-40

Species 

Attractive Nuisance 

Site Description 

Metals Concentrations in 

the Environment or Diet 

Metals Concentrations in 

the Organism 

(μg/g) Observed Effects Study Type Citation 

Common grackles 

(Quiscalus quiscala) 

Nested in close 

proximity to a coalfired power plant’s fly 

ash pond 

• Not measured in study • Eggs = 5.9 selenium • Histopathological Field Bryan et al., 

2003 

Raccoons 

(Procyon lotor) 

Lived in close 

proximity to a coalfired power plant’s ash 

pond 

• Not measured in study • Heart = 2.8 arsenic 

• Kidney = 3.2 cadmium, 

0.43 strontium 

• Muscle = 0.95 chromium 

• Liver = 0.34 lead, 1.5 

mercury 

• Histopathological Field Burger et al., 

2002 

Interior least tern 

(Sterna antillarum) 

Nested on a dike in a 

coal-fired power plant’s 

ash pond 

• Not measured in study • Not observed in study • Not observed in 

study 

Field Pruitt, 2000 

and Duke 

Energy, 2007 

Southern toads 

(Bufo terrestris) 

Inhabited an ash basin 

and nearby swamp 

Reference (control) site 

organisms were 

transferred to 

contaminated locations 

• Not measured in study • Not measured in study • Elevated 

corticosterone and 

testosterone levels 

Outdoor 

mesocosm 

Hopkins et al., 

1997 

Southern toads 

(Bufo terrestris) 

Inhabited an ash pond 

and nearby swamp 

Reference site 

organisms were 

transferred to 

contaminated locations 

• Pond sediment = 39.64 

μg/g arsenic, 4.38 μg/g 

selenium 

• Adult males = 1.58 

arsenic, 17.40 selenium 

• Histopathological Outdoor 

mesocosm 

Hopkins et al., 

1998 

Larval bullfrogs 

(Rana catesbeiana) 

Inhabited bottom ash 

ponds near a coal-fired 

power plant 

• Pond sediment = 49.39 

μg/g arsenic, 0.72 μg/g 

cadmium, 23.85 μg/g 

chromium, 84.72 μg/g 

copper, 6.11 μg/g 

selenium, 106.39 μg/g 

strontium, 45.83 μg/g 

vanadium 

• Whole body 

concentration = 33.10 

arsenic, 5.47 cadmium, 

18.25 chromium, 116.72 

copper, 20.25 selenium, 

39.89 strontium, 17.32 

vanadium 

• Morphological 

• Decreased 

swimming speeds 

Field Hopkins et al., 

2000 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-8. Summary of Attractive Nuisance Case Studies Related to Steam Electric Power Plants 

A-41

Species 

Attractive Nuisance 

Site Description 

Metals Concentrations in 

the Environment or Diet 

Metals Concentrations in 

the Organism 

(μg/g) Observed Effects Study Type Citation 

Eastern narrowmouth toads 

(Gastrophryne 

carolinensis) 

Inhabited a seleniumladen site located near a 

coal-fired power plant 

• Site water = 3.93 μg/L 

selenium 

• Soil = 38.25 μg/L 

selenium 

• Lab water = 0.28 μg/L 

selenium 

• Females = 42.40 

selenium 

• Eggs = 43.96 selenium 

• Reproductive 

• Histopathological 

Outdoor 

mescosm 

Hopkins et al., 

2006 

Barn swallow 

(Hirundo rustica) 

Nested near a seleniumladen pond associated 

with a coal-fired power 

plant 

• Not provided in the 

literature 

• Eggs = 2.8 selenium • Histopathological Field King et al., 

1994 

Slider turtles 

(Trachemys scripta) 

Inhabited a seleniumladen basin that 

receives sluiced fly ash 

near a coal-fired power 

plant 

Eggs were incubated in 

ash-contaminated soil 

• Ash-contaminated soil = 

2.56 μg/g selenium 

• Adult Females = 37.18 

(mean concentration), 

selenium 

• Reproductive Outdoor 

mescosm 

Nagle et al., 

2001 

Canada geese 

(Branta 

Canadensis) 

Inhabited pens near a 

vanadium-laden ash 

pond associated with an 

oil-fired power plant 

• Site water = 467,000 

μg/L vanadium 

• Liver = 57.3 vanadium 

• Kidney = 226 vanadium 

• Lethal 

• Histopathological 

Outdoor 

mesocosm 

Rattner et al., 

2006 

Acronyms: μg/g (Micrograms per Grams); μg/L (Micrograms per Liters). 
 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-9. Summary of Attractive Nuisance Case Studies Unrelated to Steam Electric Power Plants 

A-42

Site Name, Location, 

and Contamination 

Source Organism Affected Documented Effects Trace Metal Concentrations (ppm) Citation 

Kesterson Reservoir, CA 

Agricultural runoff 

California vole (Microtus 

californicus) 

Mean selenium concentrations in 

livers were significantly elevated. 

• Liver = 119 selenium Clark et al., 1987 

Kesterson Reservoir, CA 

Agricultural runoff 

American coot (Fulica americana), 

mallard (Anas platyrhynchos) 

Mean selenium concentrations in 

bird eggs and livers were elevated; 

organisms exhibited severe 

reproductive failure and deformities. 

• Eggs = 2.2 – 110 selenium 

• Liver = 19 – 130 selenium 

• Water = 300,000 selenium 

Ohlendorf et al., 

1986 

Kesterson Reservoir, CA 

Agricultural runoff 

Pied-billed grebes (Podilymbus 

podiceps), common moorhen 

(Gallinula chloropus), blacknecked stilts (Himantopus 

mexicanus) 

Selenium concentrations in livers 

were 10 times those found in nearby 

control areas; organisms exhibited 

severe lesions and embryonic 

deformities. 

• Liver = 94.4 selenium 

• Water = 300,000 selenium 

Ohlendorf et al., 

1988a 

Kesterson Reservoir, CA 

Agricultural runoff 

Gopher snakes (Pituophis 

melanoleucus), bullfrogs (Rana 

catesbeiana) 

Selenium concentrations in snake 

and frog livers were significantly 

elevated. 

• Snake liver = 11.1 selenium 

• Frog liver = 45.0 selenium 

Ohlendorf et al., 

1988b 

Kesterson Reservoir, CA 

Agricultural runoff 

Eared grebe (podiceps nigricollis), 

mallard (Anas platyrhynchos), 

cinnamon teal (Anas cyanoptera), 

gadwall (Anas strepera), American 

coot (Fulica americana), killdeer 

(Charadrius vociferous), blacknecked stilt (Himantopus 

mexicanus), American avocet 

(Recurvirostra americana) 

Hatchlings exhibited mortality, 

deformity, and lack of embr yonic 

development. 

• Water = 300 selenium Ohlendorf et al., 

1989 

Kesterson Reservoir, CA 

Agricultural runoff 

Mosquitofish (Gambusia 

affinis), American coot (Fulica 

americana), ducks (Anas spp.) 

Selenium concentrations in livers, 

kidneys, and muscles were elevated; 

organisms exhibited reduced body 

weight. 

• Fish = 120 – 140 selenium 

• Coot liver = 76.7 selenium 

• Duck liver = 25.2 selenium 

Ohlendorf et al., 

1990 

Liberty State Park, NJ 

Industrial and urban 

activities 

House wren (troglodytes aedon), 

American robin (Turdus 

migratorus) 

Lead, arsenic, chromium, copper, 

and iron concentrations in bird 

feathers were elevated. 

• Feather = 4,200 lead; 1,000 

chromium; 6,200 copper; 600 

arsenic 

Hofer et al., 2010 
 

Appendix A—Literature Review Methodology and Results 

Table A-9. Summary of Attractive Nuisance Case Studies Unrelated to Steam Electric Power Plants 

Site Name, Location, 

and Contamination 

Source Organism Affected Documented Effects Trace Metal Concentrations (ppm) Citation 

Meadowlands, NJ 

Industrial and urban 

activities 

Red-winged blackbird (agelaius 

phoeniceus), marsh wrens 

(Cistothorus palustris), tree 

swallow (Tachycineta bicolor) 

Lead and chromium concentrations 

in blood were elevated; mercury and 

chromium concentrations in eggs 

were elevated. 

• Swallow blood = 0.94 lead; 1.03 

chromium 

• Wren eggs = 0.2 mercury 

• Blackbird eggs = 0.12 chromium 

Tsipoura et al., 2008 

Acronym: ppm (parts per million). 

A-43
 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-10. Summary of Selenium Concentrations in the Environment and Organisms Experiencing Adverse Effects 

A-44

Species 

Route of Selenium 

Exposure 

Selenium 

Concentrations in the 

Environment (μg/L) 

or Diet (μg/g) 

Selenium Concentrations 

in the Organism (μg/g) Observed Effects 

Study Type 

(Surface Water 

Type) Citation 

Largemouth bass 

(Micropterus 

salmoides) 

Inhabited a 

selenium-laden 

cooling water 

reservoir receiving 

ash pond effluent 

from a coal-fired 

power plant 

Not provided in the 

literature 

Carcass = 2.86 (mean, 

female), 2.63 (mean, male) 

Gonad = 4.40 (mean, 

female), 2.38 (mean, male) 

Reproductive 

Histopathological 

Field 

(reservoir) 

Baumann and 

Gillespie, 1986 

Bluegill 

(Lepomis 

macrochirus) 

Carcass = 2.74 (mean, 

female), 4.64 (mean, male) 

Gonad = 4.63 (mean, 

female), 3.35 (mean, male) 

Striped bass Consumed a Red Shiners = 9.6 μg/g Skeletal muscle = 3.8 Modified behavior Laboratory Coughlan and 

(Morone saxatilis) selenium-laden diet (average whole-body (higher average Decreased growth (reservoir) Velte, 1989 

by eating red shiners concentration), wet concentration), wet Histopathological 

collected from a site Lethal 

receiving coal ash 

pond sluice water 

Bluegill Inhabited a Not provided in the Not provided in the Lethal Field (reservoir) a Crutchfield and 

(Lepomis selenium-laden literature literature Ferguson, 2000a 

macrochirus) reservoir receiving 

coal ash pond 

effluent 

Green sunfish b Inhabited a Site water c = 7 – 14 Biomass d = 2,744 – 3,793 Lethal Field (reservoir) Crutchfield, 

(Lepomis cyanellus) selenium-laden μg/L (mean) Reproductive 2000b 

reservoir receiving 

coal ash pond 

effluent 

Largemouth bass 

(Micropterus 

salmoides) e 

Pomoxis spp. 

Inhabited a 

selenium-laden 

cooling water 

reservoir receiving 

both fly ash and 

bottom ash pond 

effluent from a coalfired power plant 

Site water h = 10 μg/L Biomass i = 0.1 – 1.0 

(mean) 

Lethal 

Reproductive 

Field 

(reservoir) 

Cumbie and 

Van Horn, 1978 

Lepomis spp. f Body = 41.0 – 77.1 (54.6 

mean concentration), wet 

Lealurus spp. g Body = 0.31 – 15.5 (6.32 

mean concentration), wet 
 

 

Appendix A—Literature Review Methodology and Results 

Table A-10. Summary of Selenium Concentrations in the Environment and Organisms Experiencing Adverse Effects 

A-45

Species 

Route of Selenium 

Exposure 

Selenium 

Concentrations in the 

Environment (μg/L) 

or Diet (μg/g) 

Selenium Concentrations 

in the Organism (μg/g) Observed Effects 

Study Type 

(Surface Water 

Type) Citation 

Bluegill 

(Lepomis 

macrochirus) 

Inhabited a 

selenium-laden 

cooling water 

reservoir of a coalfired power plant 

Site water j = 9 – 12 

μg/L 

Testes = 4.37 (mean 

concentration) 

Ovaries = 6.96 (mean 

concentration) 

Reproductive Laboratory 

(reservoir) 

Gillepsie et al., 

1986 

Banded water 

snakes 

(Nerodia fasciata) 

Consumed a 

selenium-laden diet 

by eating prey 

collected from a 

contaminated site 

located near a coalfired power plant 

Prey items k = 22.7 

μg/g (geometric least 

squared mean), dry 

Gonads = 17.64 (female), 

19.06 (male) 

Kidney = 25.38 (female), 

32.04 (male) 

Liver = 24.08 (female), 

24.22 (male) 

Reproductive 

Histopathological 

Laboratory 

(not specified) 

Hopkins et al., 

2002 

Eastern narrowmouth toads 

(Gastrophryne 

carolinensis) 

Inhabited a 

selenium-laden site 

located near a coalfired power plant 

Site water = 3.93 μg/L 

Soil = 8.25 μg/L 

Lab water = 0.28 μg/L 

Females = 42.40 

Eggs = 43.96 

Reproductive 

Histopathological 

Outdoor mescosm 

(combustion 

residuals pond) 

Hopkins et al., 

2006 

Largemouth bass l 

(Micropterus 

salmoides) 

Inhabited a 

selenium-laden 

cooling water 

reservoir receiving 

effluent from the 

coal ash pond 

Ash effluent = 100-200 

μg/L 

Site water = 10 μg/L 

Visceral tissue = 40+ 

(highest mean 

concentration) 

Lethal Field 

(reservoir) 

Lemly, 1985a 

Slider turtles 

(Trachemys scripta) 

Inhabited a 

selenium-laden pond 

receiving sluiced fly 

ash near a coal-fired 

power plant 

Eggs were incubated 

in ash-contaminated 

soil 

Ash-contaminated soil 

= 2.56 μg/g, dry 

Adult females = 37.18 

(mean concentration), dry 

Reproductive Outdoor mescosm 

(combustion 

residuals pond) 

Nagle et al., 

2001 
 

 

 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-10. Summary of Selenium Concentrations in the Environment and Organisms Experiencing Adverse Effects 

A-46

Species 

Route of Selenium 

Exposure 

Selenium 

Concentrations in the 

Environment (μg/L) 

or Diet (μg/g) 

Selenium Concentrations 

in the Organism (μg/g) Observed Effects 

Study Type 

(Surface Water 

Type) Citation 

Bluegill m 

(Lepomis 

macrochirus) 

Inhabited a 

selenium-laden 

cooling water 

reservoir of a coalfired power plant 

Site water = <10–20 

μg/L 

Liver = 34 (mean 

concentration), wet 

Gonad = 12.1 (mean, 

female), 5.4 (mean, male), 

wet 

Muscle = 13 (mean 

concentration), wet 

Histopathological Field 

(reservoir) 

Sager and 

Colfield, 1984 

Largemouth bass n Liver = 10.2 (mean 

(Micropterus concentration), wet 

salmoides) Gonad = 10.3 (mean, 

female), wet 

Muscle = 6.7 (mean 

concentration), wet 

Green sunfish 

(Lepomis cyanellus) 

Inhabited a 

selenium-laden lake 

receiving coal fly 

ash, scrubber sludge, 

and coal bottom ash 

Not provided in the 

literature 

Hepatopancreas = 1.31 – 

9.30, wet 

Histopathological Field 

(lake) 

Sorensen et al., 

1982 

Redear sunfish 

(Lepomis 

microlophus) 

Hepatopancreas = 2.8 – 

11.03, wet 

Redear sunfish Inhabited a Not provided in the Liver = 20 Histopathological Field Sorensen et al., 

(Lepomis selenium-laden lake literature (lake) 1983 

microlophus) receiving coal fly 

ash, scrubber sludge, 

and coal bottom ash 

Redear sunfish Inhabited a Not provided in the Hepatopancreas = 8.4 – 27.2 Increased weight loss Field Sorensen and 

(Lepomis selenium-laden lake literature μg/L (lake) Bauer, 1984a 

microlophus) receiving coal ash 

pond wastewater 

Kidney = 11.4 – 115.7 μg/L 

Ovaries = 0 – 5.9 μg/L 

Testes = 0 – 54.2 μg/L 

Green sunfish Inhabited a Site water = 13 μg/L Liver = 21.4, wet Histopathological Field Sorensen et al., 

(Lepomis cyanellus) selenium-laden lake Sediment = 5 – 14 Skeletal muscle = 12.9, wet Hematological (lake) 1984b 

receiving coal fly 

ash sluice water 

μg/g, dry Hematocrit = 33, wet 
 

 

 

 

 

 

 

 

Appendix A—Literature Review Methodology and Results 

Table A-10. Summary of Selenium Concentrations in the Environment and Organisms Experiencing Adverse Effects 

A-47

Species 

Route of Selenium 

Exposure 

Selenium 

Concentrations in the 

Environment (μg/L) 

or Diet (μg/g) 

Selenium Concentrations 

in the Organism (μg/g) Observed Effects 

Study Type 

(Surface Water 

Type) Citation 

Redear sunfish 

(Lepomis 

microlophus) 

Inhabited a 

selenium-laden lake 

located near a coalfired power plant 

Not provided in the 

literature 

Liver = 7.63 (mean 

concentration) 

Histopathological 

Reproductive 

Field 

(lake) 

Sorensen, 1988 

Acronyms: kg/ha (kilogram per hectacre); μg/L (micrograms per liter); μg/g (micrograms per gram).
 

a – The data used in this study were census data collected from routine biological monitoring undertaken by the facility.
 

b – Multiple fish species were studied; however, the green sunfish had the highest documented selenium biomass concentrations.
 

c – These are the selenium water concentrations detected prior to the conversion to a dry fly ash handling system.
 

d – This concentration is measured in the units kg/ha. The range of selenium concentrations was reported annually from 1982 to 1989, before the power plant
 

converted to dry ash handling.
 

e – Multiple fish species were studied; however, the largemouth bass and pomoxis spp. had the lowest documented selenium biomass concentrations.
 

f – Multiple fish species were studied; however, the Lepomis spp. had the highest documented selenium skeletal muscle concentrations.
 

g – Multiple fish species were studied; however, the Letalurus spp. had the lowest documented selenium body concentrations.
 

h – This selenium concentration is dissolved.
 

i – This concentration is measured in the units kg/ha. The range of selenium concentrations was reported annually from 1982 to 1989, before the power plant
 

converted to dry ash handling. Both fish species had the same range of selenium concentrations.
 

j – This concentration was not measured for this study but was reported in a previous study conducted at the same site.
 

k – The banded water snakes were fed weekly combinations of previously frozen prey items inhabiting the coal ash-contaminated site.
 

l – The study documented only selenium concentrations for the largemouth bass.
 

m – Multiple fish species were studied; however, the bluegills had the highest documented selenium liver tissue concentration.
 

n – Multiple fish species were studied; however, the largemouth bass had the lowest documented selenium liver tissue concentration.
 
 

 

 

Appendix B—Proximity Analyses Supporting Tables 

APPENDIX B 

PROXIMITY ANALYSES SUPPORTING TABLES 

Table B-1. Immediate Receiving Waters 303(d) Impairments Listing 

Cause Group Name Cause Name 

Found in 

Combustion 

Wastewater 

Evaluated in 

the EA 

Algal Growth Algal Growth 

Algal Growth Chlorophyll-A 

Ammonia Ammonia  

Ammonia Ammonia, Un-Ionized  

Ammonia Total Ammonia  

Cause Unknown Cause Unknown 

Cause Unknown - Impaired Biota Benthic Macroinvertebrates 

Cause Unknown - Impaired Biota Benthic Macroinvertebrates 

Bioassessments 

Cause Unknown - Impaired Biota Biological 

Cause Unknown - Impaired Biota Biology 

Cause Unknown - Impaired Biota Estuarine Bioassessments 

Cause Unknown - Impaired Biota Fish Bioassessments 

Cause Unknown - Impaired Biota Fish Community Rated Poor 

Cause Unknown - Impaired Biota Impaired Biotic Communities 

Dioxins 2,3,7,8-Tetrachlorodibenzo-P-Dioxin 

(Only) 

Dioxins Dioxin 

Dioxins Dioxins 

Fish Consumption Advisory Commercial Fishing Ban 

Fish Consumption Advisory Fish Consumption Advisory 

Flow Alteration(s) Flow Alteration(s) 

Habitat Alterations Habitat 

Habitat Alterations Habitat Alterations 

Habitat Alterations Other Habitat Alteration(s) 

Mercury Fish Advisories - Mercury  

Mercury Fish Consumption Advisory - Mercury  

Mercury Mercury  

Mercury Mercury In Fish Tissue  

Mercury Methyl Mercury  

Metals (Other Than Mercury) Aluminum  

Metals (Other Than Mercury) Arsenic  

Metals (Other Than Mercury) Beryllium  

Metals (Other Than Mercury) Cadmium  

Metals (Other Than Mercury) Chromium  

Metals (Other Than Mercury) Copper  

B-1
 
 

 

 

 

Appendix B—Proximity Analyses Supporting Tables 

Table B-1. Immediate Receiving Waters 303(d) Impairments Listing 

Cause Group Name Cause Name 

Found in 

Combustion 

Wastewater 

Evaluated in 

the EA 

Metals (Other Than Mercury) Iron  

Metals (Other Than Mercury) Lead  

Metals (Other Than Mercury) Manganese  

Metals (Other Than Mercury) Metals (Other Than Mercury)  

Metals (Other Than Mercury) Selenium  

Metals (Other Than Mercury) Silver  

Metals (Other Than Mercury) Zinc  

Noxious Aquatic Plants Macrophytes 

Noxious Aquatic Plants Noxious Aquatic Plants 

Nuisance Exotic Species Exotic Species 

Nutrients Eutrophication  

Nutrients Inorganic N  

Nutrients Nitrates  

Nutrients Nitrogen, Total  

Nutrients Nutrient/Eutrophication Biological 

Indicators 

 

Nutrients Nutrients  

Nutrients Phosphorus  

Nutrients Phosphorus, Total  

Oil And Grease Oil 

Oil And Grease Oil And Grease 

Organic Enrichment/Oxygen 

Depletion 

Carbonaceous Biochemical Oxygen 

Demand (BOD) 



Organic Enrichment/Oxygen 

Depletion Dissolved Oxygen 

Organic Enrichment/Oxygen 

Depletion Dissolved Oxygen Saturation 

Organic Enrichment/Oxygen 

Depletion Nitrogenous BOD 

Organic Enrichment/Oxygen 

Depletion 

Organic Enrichment/Low Dissolved 

Oxygen 



Pathogens Bacteria 

Pathogens Bacterial Slimes 

Pathogens Coliforms 

Pathogens Enterococcus Bacteria 

Pathogens Escherichia Coli (E. Coli) 

Pathogens Fecal Coliform 

Pathogens Pathogens 

Pathogens Total and Fecal Coliform 

Pathogens Total Coliform 

Pesticides Atrazine 

Pesticides Chlordane 

B-2
 
 

 

 

Appendix B—Proximity Analyses Supporting Tables 

Table B-1. Immediate Receiving Waters 303(d) Impairments Listing 

Cause Group Name Cause Name 

Found in 

Combustion 

Wastewater 

Evaluated in 

the EA 

Pesticides Chlorpyrifos 

Pesticides DDT 

(Dichlorodiphenyltrichloroethane) 

Pesticides Dieldrin 

Pesticides Mirex 

Pesticides Organochlorine Pesticides 

Pesticides Pesticides 

pH/Acidity/Caustic Conditions pH 

Polychlorinated Biphenyls (PCBs) Commercial Fishing Ban - PCBs 

PCBs Fish Consumption Advisory - PCBs 

PCBs PCBs In Fish Tissue 

PCBs PCBs 

PCBs Priority Organics - PCBs 

Salinity/Total Dissolved 

Solids/Chlorides/Sulfates Chloride  

Salinity/Total Dissolved 

Solids/Chlorides/Sulfates 

Salinity/Total Dissolved 

Solids/Chlorides 

 

Salinity/Total Dissolved 

Solids/Chlorides/Sulfates Sulfates 

Salinity/Total Dissolved 

Solids/Chlorides/Sulfates Total Dissolved Solids (TDS)  

Sediment Sediment 

Sediment Sedimentation/Siltation 

Sediment Siltation 

Sediment Suspended Sediment 

Taste, Color, And Odor Taste, Color, and Odor 

Temperature Temperature 

Temperature Thermal Modifications 

Total Toxics Aquatic Toxicity 

Total Toxics Toxics 

Toxic Inorganics Boron  

Toxic Inorganics Cyanide 

Toxic Inorganics Other Inorganics 

Toxic Organics Polycyclic Aromatic Hydrocarbons 

(PAHs) (Aquatic Ecosystems) 

Toxic Organics Priority Organic Compounds 

Turbidity Suspended Solids 

Turbidity Total Suspended Solids (TSS) 

Turbidity Turbidity 

Source: 303(d) Listed Impaired Waters National Hydrography Data (NHD) Indexed Dataset. Reach Address 

Database (RAD). Extracted on March 31, 2011. Available online at: 

http://www.epa.gov/waters/data/downloads.html. (DCN SE03556). 

B-3
 
 

 

 

Appendix B—Proximity Analyses Supporting Tables 

Table B-2. Immediate Receiving Waters Fish Consumption Advisory Listing 

Pollutant 

Found in Combustion 

Wastewater Evaluated in the EA a 

Cadmium  

Chlordane 

Chlorinated pesticides 

DDT 

Dieldrin 

Dioxin 

Lead  

Mercury  

Mirex 

Not Specified 

PCBs (Total) 

Perfluorooctane sulfonate 

Toxaphene 

Source: Fish Consumption Advisories NHD Indexed Dataset. RAD. Available online at: 

http://epamap32.epa.gov/radims/. (DCN SE03558). 

a – The number and percentage of immediate receiving waters issued a fish consumption advisory for the pollutants 

evaluated in the EA are presented in Table 3-12. 

B-4
 
 

 

 

 

 

 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

APPENDIX C 

WATER QUALITY MODEL METHODOLOGY 

This appendix presents the model equations, input values (including site-specific default 

model assumption values) and pollutant benchmarks, and methodology limitations/assumptions 

for the water quality model. 

The water quality model equations are organized by the methodology for nonvolatile 

metals (i.e., arsenic, cadmium, chromium (VI), copper, lead, nickel, selenium, thallium, and 

zinc) and volatile metals (i.e., mercury). The U.S. Environmental Protection Agency (EPA) used 

the equations to calculate total and dissolved receiving water concentrations and total sediment 

concentrations in the immediate discharge zone. Model input requirements for the equations 

presented in Appendix C can be divided into four major categories: (1) input variable described 

by another equation; (2) site-specific input value; (3) default model assumption value; and (4) 

site-specific assumption value based on predetermined data. The following tables in Appendix C 

describe the input requirements and data sources used in the water quality model: 

•	 Table C-1. Site-Specific Model Input Variables; 

•	 Table C-2. Default Model Assumption Input Variables; 

•	 Table C-3. Site-Specific Model Assumption Input Variables; 

•	 Table C-4. Surface Water Partition Coefficients; 

•	 Table C-5. Total Suspended Solids (TSS) Concentrations in Lakes and Rivers; 

•	 Table C-6. Regional Surface Water Temperatures; and 

•	 Table C-7. National Recommended Water Quality Criteria (NRWQC) and Drinking 

Water Maximum Contaminant Level (MCL) Benchmarks. 

EPA used the immediate receiving-water-specific pollutant loading values for total 

metals in the water quality model, except for chromium VI. EPA estimated the total pollutant 

loading from the evaluated waste streams on a per immediate-receiving-water basis. However, 

some plants discharge to multiple receiving waters and therefore, EPA divided the plant-specific 

loadings accordingly among the receiving waters based on water diagrams provided in 

Questionnaire for the Steam Electric Power Generating Effluent Guidelines (Steam Electric 

Survey) responses. EPA evaluated the environmental impacts from 281 steam electric power 

plants in the receiving water quantitative analysis (297 unique immediate receiving waters). 

EPA modeled chromium VI in the water quality model, but did not take into 

consideration arsenic or mercury speciation in the water quality model. EPA included 

assumptions of metal speciation as appropriate in the subsequent wildlife and human health 

models (see Appendix D and Appendix E, respectively). EPA used total selenium loadings in the 

water quality model; however, due to the partition coefficients available, EPA assumed the 

dominant form of selenium in the receiving water was selenate (i.e., selenium VI). Although 

selenium speciation likely occurs within combustion residuals surface impoundments prior to 

discharge, EPA selected the selenate partition coefficient because it is expected to be the 

predominant form present in well-oxygenated alkaline surface waters and the rate of conversion 

C-1
 
 

 

 

 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

between selenate and selenite (i.e., selenium IV) is reported to be slow in most natural waters 

[U.S. EPA, 2004]. 

Water Quality Model Equations 

EPA calculated the nonvolatile metal concentrations for the following compartments 

within the receiving water: 

• Total pollutant concentration in water column (Cwc); 

• Dissolved pollutant concentration in water column (Cdw); and 

• Total pollutant concentration in sediment (Cbs). 

EPA used the equations presented below to calculate receiving water concentrations for 

arsenic, cadmium, chromium (VI), copper, lead, mercury, nickel, selenium, thallium, and zinc 

discharging. 

EQUATION C-1 

Ltotal CwTot, Rivers
 = (Qcool + Q ) × fwater + Kwt× Vriver
 river 

where: 

CwTot,Rivers = 

Total water body concentration (water and 

sediment) in rivers and streams from 

loading (grams per cubic meter [g/m3] or 

milligrams per liter [mg/L]) 

Output from Equation C-1 

Ltotal = Total metal loading from steam effluent 

(grams per day [g/day]) 

Output from engineering 

analysis 

(see Table C-1) 

Qcool = Total cooling water effluent flow (cubic 

meters per day [m3

/day]) 

Output from engineering 

analysis 

(see Table C-1) 

Qriver = Receiving water average annual flow 

(m3/day) 

NHD Plus 

(see Table C-1) 

fwater = 

Fraction of contaminant in water column 

(unitless) Output from Equation C-6 

Kwt = Water concentration dissipation rate 

constant (1/day) Output from Equation C-10 

Vriver = Flow independent mixing volume for 

rivers (m3) Output from Equation C-11 

C-2
 
 

 

 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

EQUATION C-2 

Ltotal CwTot, Lake = (Qcool + Qlake ) × fwater + Kwt× Vlake 

where: 

CwTot, Lake = 

Total water body concentration (water and 

sediment) in lakes from loading (g/m3 or 

mg/L) 

Output from Equation C-1 

Ltotal = 

Total metal loading from steam effluent 

(g/day) 

Output from engineering 

analysis 

(see Table C-1) 

Qcool = Total cooling water effluent flow (m3/day) 

Output from engineering 

analysis 

(see Table C-1) 

Qlake = Average annual flow for rivers and streams 

exiting the lake (m3/day) 

NHD Plus 

(see Table C-1) 

fwater = 

Fraction of contaminant in water column 

(unitless) Output from Equation C-6 

Kwt = Water concentration dissipation rate constant 

(1/day) Output from Equation C-10 

Vlake = Flow independent mixing volume (m3) Output from Equation C-11 

EQUATION C-3 

dz Cwc = fwater × Cwtot (Rivers or Lakes) × dw 

where: 

Cwc = Total pollutant concentration in water (mg/L) Output from Equation C-3 

fwater = Fraction of total water body contaminant in 

water column (unitless) 

Output from Equation C-6 

CwTot 

(Rivers or 

Lakes) 

= 

Total water body concentration (water and 

sediment) in rivers or lakes from loading 

(g/m3 or mg/L) 

Output from Equation C-1 

or 

Equation C-2 

dz = Depth of the water body (meters [m]) Output from Equation C-9 

dw = Depth of water column (m) 

River or stream output from 

Equation C-7 

Lake or Pond 

Site-specific value 2 

2 For lakes, ponds, and reservoirs, EPA used site-specific values for the depth of the water body. See the ERG memorandum 

Water Quality Model: Plant and Receiving Water Characteristics [ERG, 2013a] for further details. 

C-3
 
Cdw = Cwc 

1 

1 + Kdsw × TSS × 0.000001 ൬ ൰ 

 

 

 

 

 

 

dw 1 + Kdsw × TSS × 0.000001 × dz r = dw db ቈ[1 + (Kdsw × TSS × 0.000001)] × ቉ + ൤(bsp + Kdbs × bsc) × ൨ dz dz 

 

 

Appendix C—Water Quality Model Methodology 

EQUATION C-4 

where: 

Cdw = 

Dissolved pollutant concentration in water 

(mg/L) 

Output from 

Equation C-4 

Cwc = Total pollutant concentration in water (mg/L) Output from Equation C-3 

Kdsw = Suspended sediment-surface water partition 

coefficient (milliliters per gram [mL/g]) 

Assumed value 

(see Table C-2 and Table 

C-4) 

TSS = Total suspended solids (mg/L) 

Assumed value 

(see Table C-3 and Table 

C-5) 

0.000001 = Conversion factor (L/mL)(g/mg) Conversion factor 

EQUATION C-5 

dz Cbs = fBenth × Cwtot (Rivers or Lakes) × db 

where: 

Cbs = Total pollutant concentration in sediment 

(mg/L) Output from Equation C-5 

fBenth = 

Fraction of total water body contaminant in 

benthic sediments (unitless) Output from Equation C-15 

CwTot 

(Rivers or 

Lakes) 

= 

Total water body concentration (water and 

sediment) in rivers or lakes from loading 

(g/m3 or mg/L) 

Output from Equation C-1 

or 

Equation C-2 

dz = Depth of the water body (m) Output from Equation C-9 

db = Depth of upper benthic layer (m) Assumed value of 0.03 m 

(see Table C-2) 

EQUATION C-6 

[ ( )] 

fwate

where: 

fwater = 

Fraction of contaminant in water column 

(unitless) Output from Equation C-6 

C-4
 
 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

Kdsw = Suspended sediment-surface water partition 

coefficient (mL/g) 

Assumed value 

(see Table C-2 and Table 

C-4) 

TSS = Total suspended solids (mg/L) 

Assumed value 

(see Table C-3 and Table 

C-5) 

0.000001 = Conversion factor (L/mL)(g/mg) Conversion factor 

dw = Depth of water column (m) 

River or stream output from 

Equation C-7 

Lake or pond 

site-specific value 3 

dz = Depth of the water body (m) Output from Equation C-9 

bsp = Bed sediment porosity (cubic centimeter per 

cubic centimeter [cm3

/cm3]) 

Assumed value of 0.6 

cm3/cm3 

(see Table C-2) 

Kdbs = 

Bottom sediment-pore water partition 

coefficient (mL/g) 

Assumed value 

(see Table C-2 and Table 

C-4) 

bsc = 

Bed sediment particle concentration (gram 

per cubic centimeter [g/cm3]) or (kilogram 

per liter [kg/L]) 

Assumed value of 1 g/cm3 

(see Table C-2) 

db = Depth of upper benthic layer (m) Assumed value of 0.03 m 

(see Table C-2) 

EQUATION C-7 

dw = 

Qriver 

v × Width 

where: 

dw = Depth of water column (m) Output from Equation C-7 

Qriver = Receiving water flow (m3/s) NHD Plus 

(see Table C-1) 

v = Receiving water velocity (m/s) NHD Plus 

(see Table C-1) 

Width = Receiving water width (m) Output from Equation C-8 

3 For lakes, ponds, and reservoirs, EPA used site-specific values for the depth of the water body. See the ERG memorandum 

Water Quality Model: Plant and Receiving Water Characteristics [ERG, 2013a] for further details. 

C-5
 
 

 

 

 

 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

EQUATION C-8 

Width 0.4559 = 5.1867 × Qriver 

where: 

Width = Receiving water width (m) Output from Equation C-8 

Qriver = Receiving water flow (m3/s) NHD Plus 

(see Table C-1) 

EQUATION C-9 

dz = db + dw 

where: 

dz = Depth of the water body (m) 

River or stream 

output from Equation C-9 

Lake or pond 

site-specific value 

(see Table C-1) 4 

db = Depth of upper benthic layer (m) Assumed value 0.03 m 

(see Table C-2) 

dw = Depth of water column (m) 

River or stream 

output from Equation C-7 

Lake or pond 

site-specific value 5 

EQUATION C-10 

Kwt = (fwater × ksw) + (fbenth × ksed ) + (fwater × kvol) + (fbenth × Kb) 

where: 

Kwt = 

Water concentration dissipation rate constant 

(1/day) for nonvolatile metals (see Equation 

C-16 for volatile metals) 

Output from Equation C-10 

fwater = 

Fraction of total water body contaminant in 

water column (unitless) Output from Equation C-6 

ksw = Degradation rate for water column (1/day) Assumed value of 0/day 

(see Table C-2) 

4 For lakes, ponds, and reservoirs, EPA used site-specific values for the depth of the water body. See the ERG memorandum 

Water Quality Model: Plant and Receiving Water Characteristics [ERG, 2013a] for further details. 

5 For lakes, ponds, and reservoirs, EPA used site-specific values for the depth of the water body. See the ERG memorandum 

Water Quality Model: Plant and Receiving Water Characteristics [ERG, 2013a] for further details. 

C-6
 
 

 

 

 

Appendix C—Water Quality Model Methodology 

fbenth = Fraction of total water body contaminant in 

benthic sediments (unitless) Output from Equation C-15 

ksed = Degradation rate for sediment (1/day) Assumed value of 0/day 

(see Table C-2) 

kvol = 

Water column volatilization loss rate 

constant (1/day) 

Assumed value of 0/day 

(see Table C-2) 

Kb = Benthic burial rate constant (1/day) Output from Equation C-14 

EQUATION C-11 

Vriver = Width × Len × dz 

where: 

Vriver = Flow independent mixing volume for rivers 

and streams (m3) Output from Equation C-11 

Width = Receiving water width (m) Output from Equation C-8 

Len = Length of stream reach (m) NHD Plus 

(see Table C-1) 

dz = Depth of the water body (m) Output from Equation C-9 

EQUATION C-12 

Vlake = Area × dz,lake 

where: 

Vlake = Flow independent mixing volume for lakes 

and ponds (m3) Output from Equation C-12 

Area = Surface area of the lake (m) NHD Plus 

(see Table C-1) 

dz,lak e = Depth of the lake (m) Site-specific evaluations 

(see Table C-1) 

EQUATION C-13 

fd = 

1 

1 + Kdsw × TSS × 0.000001 

where: 

fd = Dissolved fraction in water (unitless) Output from Equation C-13 

Kdsw = Suspended sediment-surface water partition 

coefficient (mL/g) 

Assumed value 

(see Table C-2 and Table 

C-4) 

C-7
 
 

 

 

 

Appendix C—Water Quality Model Methodology 

TSS = Total suspended solids (mg/L) 

Assumed value 

(see Table C-3 and Table 

C-5) 

0.000001 = Conversion factor (L/mL)(g/mg) Conversion factor 

EQUATION C-14 

Kb = fbenth × 

WB 

db 

where: 

Kb = Benthic burial rate constant (1/day) Output from Equation C-14 

fBenth = 

Fraction of contaminant in benthic sediments 

(unitless) Output from Equation C-15 

WB = Rate of burial (m/day) Assumed value of 0 m/day 

(see Table C-2) 

db = Depth of upper benthic layer (m) Assumed value of 0.03 m 

(see Table C-2) 

EQUATION C-15 

db (bsp + Kdbs × bsc) × dz fBenth = 

dw db ቈ[1 + (Kdsw × TSS × 0.000001)] × ቉ + ൤(bsp + Kdbs × bsc) × ൨ dz dz 

where: 

fBenth = Fraction of total water body contaminant in 

benthic sediments (unitless) 

Output from 

Equation C-15 

bsp = Bed sediment porosity (cm3/cm3) 

Assumed value of 0.6 

cm3/cm3 

(see Table C-2) 

Kdbs = 

Bottom sediment-pore water partition 

coefficient (mL/g) 

Assumed value 

(see Table C-2 and Table 

C-4) 

bsc = 

Bed sediment particle concentration (g/cm3) 

or (kg/L) 

Assumed value of 1 g/cm3 

(see Table C-2) 

db = Depth of upper benthic layer (m) Assumed value of 0.03 m 

(see Table C-2) 

dz = Depth of the water body (m) Output from Equation C-9 

Kdsw = Suspended sediment-surface water partition 

coefficient (mL/g) 

Assumed value 

(see Table C-2 and Table 

C-4) 

C-8
 
 

 

 

 

 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

TSS = Total suspended solids (mg/L) 

Assumed value 

(see Table C-3 and Table 

C-5) 

0.000001 = Conversion factor (L/mL)(g/mg) Conversion factor 

dw = Depth of water column (m) River or stream output from 

Equation C-7 

Lake or pond 

site-specific value 6 

EPA calculated the volatile metal concentrations in each of the three compartments 

within the receiving water by building off the equations used to calculate nonvolatile metal 

concentrations. Kwt in Equation C-10 was replaced with a Kwt factor (see Equation C-16) that 

takes into account volatilization (kvol). EPA used the equations presented below to calculate 

receiving water concentrations for mercury only. 

EQUATION C-16 

Kwt, volatile = (fwater × ksw) + (fbenth × ksed ) + (fwater × fd × kvol) + (fbenth × Kb) 

where: 

Kwt, volatile = Water concentration dissipation rate constant 

(1/day) Output from Equation C-16 

fwater = 

Fraction of contaminant in water column 

(unitless) Output from Equation C-6 

ksw = Degradation rate for water column (1/day) Assumed value of 0/day 

(see Table C-2) 

fbenth = 

Fraction of contaminant in benthic sediments 

(unitless) Output from Equation C-15 

ksed = Degradation rate for sediment (1/day) Assumed value of 0/day 

(see Table C-2) 

fd = Dissolved fraction in water (unitless) Output from Equation C-13 

kvol = 

Water column volatilization loss rate 

constant (1/day) Output from Equation C-17 

Kb = Benthic burial rate constant (1/day) Output from Equation C-14 

EQUATION C-16 

Kv × fd kvol = dw 

6 For lakes, ponds, and reservoirs, EPA used site-specific values for the depth of the water body. See the ERG memorandum 

Water Quality Model: Plant and Receiving Water Characteristics [ERG, 2013a] for further details. 

C-9
 
 

 

 

 1 Tw-Thic Kv = θwater 

ቀ 1 ቁ + ൮ 1 ൲ KL Kg × 

HLC 

R × Tw

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

where: 

kvol = 

Water column volatilization loss rate 

constant (1/day) Output from Equation C-17 

Kv = Diffusion transfer rate (m/day) Output from Equation C-18 

fd = Dissolved fraction in water (unitless) Output from Equation C-13 

dw = Depth of water column (m) 

River or stream output from 

Equation C-7 

Lake or pond 

site-specific value 7 

EQUATION C-17 

where: 

Kv = Diffusion transfer rate (m/day) Output from Equation C-18 

Θwater = Temperature correction (unitless) Assumed value of 1.026 

(see Table C-2) 

Tw = Temperature of the water body (degrees 

Kelvin [°K]) 

Assumed value 

(see Table C-3 and Table 

C-6) 

Thlc = Temperature of HLC (°K) Assumed value of 298 

(see Table C-2) 

KL = Liquid-phase transfer coefficient (m/day) 

River or stream 

output from Equation C-19 

Lake or pond 

output from Equation C-21 

Kg = Gas-phase transfer coefficient (m/day) 

River or stream 

assumed value of 100 m/day 

(see Table C-2) 

Lake or pond 

output from Equation C-23 

7 For lakes, ponds, and reservoirs, EPA used site-specific values for the depth of the water body. See the ERG memorandum 

Water Quality Model: Plant and Receiving Water Characteristics [ERG, 2013a] for further details. 

C-10
 
 

 

 

 

 

 

 × ቆ k0.33 

a KL(Lakes) = ඥcd × w10 × ඨ

ρ ቇ × Scw 

-0.67 × 86,400 

ρw λ2

 

Appendix C—Water Quality Model Methodology 

HLC = Henry's Law Constant (atm-m3/mole) 8 

Assumed value of 0.0113 

atm-m3/mol 

(see Table C-2) 

R = Ideal gas constant (atm-m3/°K-mole) 

Assumed value of 

0.00008205 

(see Table C-2) 

EQUATION C-18 

= ඨ10-4 × Dw × v 

KL(Rivers) × 86,400 dz 

where: 

KL(Rivers) = Liquid-phase transfer coefficient (m/day) River or stream 

output from Equation C-19 

Dw = Diffusivity of the chemical in water (square 

centimeter per second [cm2/s]) Output from Equation C-20 

v = Receiving water velocity (m/s) NHD Plus 

(see Table C-1) 

dz = Depth of water body (m) Output from Equation C-9 

86,400 = Conversion factor (s/day) Conversion factor 

EQUATION C-19 

22×10-5 

Dw = ⁄ MW2 3

where: 

Dw = Diffusivity of the chemical in water (cm2/s) Output from Equation C-20 

MW = Molecular weight Known value 

(see Table C-2) 

EQUATION C-20 

8 Units for Henry’s Law Constant are atmospheres of absolute pressure (atm) per cubic meter (m3

) per mole (mol). 

C-11
 
 

 = ඥC d × W10 × ቆ

k0.33 

-0.67 K × 86,400 g(Lakes) ቇ × Sca λ2 

Appendix C—Water Quality Model Methodology 

where: 

KL(Lakes) = Liquid-phase transfer coefficient (m/day) Lake or pond output from 

Equation C-21 

Cd = Drag coefficient (unitless) Assumed value of 0.0011 

(see Table C-2) 

W10 = Wind velocity 10 meters above water surface 

(m/s) 

Site-specific data 

(see Table C-3) 

ρa = Density of air corresponding to water 

temperature (g/cm3

) 

Assumed value of 0.0012 

g/cm3 

(see Table C-2) 

ρw = Density of water corresponding to water 

temperature (g/cm3) 

Assumed value of 1 g/cm3 

(see Table C-2) 

k = Von Karman’s constant (unitless) Assumed value of 0.4 

(see Table C-2) 

λ2 = Dimensionless viscous sublayer thickness 

(unitless) 

Assumed value of 4 

(see Table C-2) 

Scw = Water Schmidt number (dimensionless) Output from Equation C-22 

86,400 = Conversion factor (s/day) Conversion factor 

EQUATION C-21 

μw Scw = 

ρw × Dw

where: 

Scw = Water Schmidt number (dimensionless) Output from Equation C-22 

μw = Viscosity of water corresponding to water 

temperature (g/cm-s) 

Assumed value of 0.0169 

g/cm-s 

(see Table C-2) 

ρw = Density of water corresponding to water 

temperature (g/cm3) 

Assumed value of 1 g/cm3 

(see Table C-2) 

Dw = Diffusivity of the chemical in water (cm2/s) Output from Equation C-20 

EQUATION C-22 

C-12
 
 

 

 

 

Appendix C—Water Quality Model Methodology 

where: 

Kg(lakes) = Gas-phase transfer coefficient (m/day) Lakes and ponds 

output from Equation C-23 

Cd = Drag coefficient (unitless) Assumed value of 0.0011 

(see Table C-2) 

W10 = Wind velocity 10 meters above water surface 

(m/s) 

Site-specific data 

(see Table C-3) 

k = Von Karman’s constant (unitless) Assumed value of 0.4 

(see Table C-2) 

λ2 = Dimensionless viscous sublayer thickness 

(unitless) 

Assumed value of 4 

(see Table C-2) 

Sca = Air Schmidt number (dimensionless) Output from Equation C-24 

86,400 = Conversion factor (s/day) Conversion factor 

EQUATION C-23 

(1.32 + 0.009Ta) × 105 

Sca = 1.9 

MW2 3⁄

where: 

Sca = Air Schmidt number (dimensionless) Output from Equation C-24 

Ta = Air temperature °K Site-specific data 

(see Table C-3) 

MW = Molecular weight Known value 

(see Table C-2) 

EPA calculated the potential negative impact to aquatic organisms from direct contact 

with the surface water of receiving water bodies using the equation presented below. 

EQUATION C-24 

Cwc HQ = sw CSCLsw 

where: 

HQsw = Hazard quotient for contact with surface 

water Output from Equation C-25 

Cwc = Total pollutant concentration in water 

(mg/L) Output from Equation C-3 

CSCLsw = Ecological benchmark for surface water 

(mg/L) 

Receptor-specific assumed 

value 

(see Table C-2 and Table C-7) 

C-13
 
 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

Water Quality Model Inputs 

Table C-1. Site-Specific Model Input Variables 

Input 

Variable Input Category and Description Data Source 

Ltotal Plant-specific effluent characteristic 

Total water body loading 

EPA estimated the pollutant discharge loadings using the 

methodology presented in Section 10 of the Steam Electric 

Power Generating Point Source Category TDD [U.S. EPA, 

2013b]. 

Qcool Plant-specific effluent characteristic 

Total cooling water effluent flow 

by receiving water 

EPA determined the estimated cooling water flow for each 

plant by outfall based an assessment of industry survey results 

using the methodology outlined in Water Quality Model: Plant 

and Receiving Water Characteristics [ERG, 2013a]. 

Qriver Receiving water characteristic for 

rivers and streams 

Water body annual flow 

EPA extracted average annual flow values from the NHD Plus 

dataset using the methodology outlined in Water Quality 

Model: Plant and Receiving Water Characteristics [ERG, 

2013a]. The NHD Plus dataset includes estimated mean annual 

flow values for each stream reach within the network using the 

Vogel Method [Vogel et al., 1999]. 

v Receiving water characteristic for 

rivers and streams 

Receiving water velocity 

EPA extracted average annual velocity values from the NHD 

Plus dataset using the methodology outlined in Water Quality 

Model: Plant and Receiving Water Characteristics [ERG, 

2013a]. The NHD Plus dataset includes estimated mean annual 

velocity values for each stream reach within the network using 

the Jobson Method (Jobson, 1996). 

Len Receiving water characteristic for 

rivers and streams 

Length of stream reach 

EPA estimated the stream reach length based on outfall 

locations using the methodology described in Water Quality 

Model: Plant and Receiving Water Characteristics [ERG, 

2013a]. 

Qlake Receiving water characteristic for 

lakes, ponds, and reservoirs 

Average discharge flow exiting the 

lake/pond system 

EPA extracted average annual flow values from the NHD Plus 

dataset using the methodology outlined in Water Quality 

Model: Plant and Receiving Water Characteristics [ERG, 

2013a]. The NHD Plus dataset includes estimated mean annual 

flow values for the stream reach exiting the lake using the 

Vogel Method (Vogel et al., 1999). 

Area Receiving water characteristic for 

lakes, ponds, and reservoirs 

Surface area of the lake, pond, or 

reservoir 

EPA estimated the lake surface area based on NHD Plus data 

or site-specific sources as described in Water Quality Model: 

Plant and Receiving Water Characteristics [ERG, 2013a]. 

dz,lake Receiving water characteristic for 

lakes, ponds, and reservoirs 

Depth of the lake, pond, or 

reservoir 

EPA estimated the depth of the lake based on site-specific data 

as described in Water Quality Model: Plant and Receiving 

Water Characteristics [ERG, 2013a]. 

C-14
 
 

 

 

 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

Table C-2. Default Model Assumption Input Values 

Input Variable Description 

Assumed 

Value Assumption Rationale 

bsp Bed sediment porosity 0.6 cm3/cm3 Bed sediment porosity is the volume of water 

per volume of benthic space with typical values 

ranging between 0.8 and 0.4 [U.S. EPA, 1998b]. 

EPA selected an average value to use for this 

input variable. 

bsc Bed sediment particle 

concentration 

1 g/cm3 Bed sediment particle concentrations typically 

range between 0.5 to 1.5 g/cm3 [U.S. EPA, 

1998d]. EPA selected an average value to use 

for this input variable. 

db Depth of upper benthic 

layer 

0.03 m The upper benthic layer variable represents the 

portion of the bed in equilibrium with the water 

column. Typical values can range from 0.01 to 

0.05 m (U.S. EPA, 1998b). EPA selected an 

average value to use for this input variable. 

ksw Degradation rate for water 

column 

0/day EPA did not assume any loss from metal 

degradation in the water column, as an 

environmentally conservative assumption. 

kvol Water column volatilization 

rate constant 

0/day EPA selected a volatilization rate of 0 for 

nonvolatile metals. 

ksed Degradation rate for 

sediment 

0/day EPA did not assume any loss from metal 

degradation in the sediment, as an 

environmentally conservative assumption. 

WB Rate of burial 0/day EPA did not assume any metal loss from burial 

within the water body sediments, as an 

environmentally conservative assumption, 

Θwater Temperature correction 1.026 

unitless 

EPA selected the temperature correction factor 

based on the value provided in U.S. EPA, 1998b. 

Kg(Rivers) Gas phase transfer 

coefficient for rivers or 

streams 

36,500 m/yr 

(100 m/day) 

EPA selected the gas phase transfer coefficient 

for rivers and streams based on the value 

provided in U.S. EPA, 1998b. 

R Ideal gas constant 0.00008205 

atm-m3/ 

K-mole 

The ideal gas constant is a known chemical 

constant. 

Cd Drag coefficient 0.0011 

unitless 

EPA selected the drag coefficient based on the 

value provided in U.S. EPA, 1998b. 

ρa Density of air 

corresponding to water 

temperature 

0.0012 

g/cm3 

EPA selected the density of air corresponding to 

water temperature based on the value provided 

in U.S. EPA, 2005b. 

ρw Density of water 

corresponding to water 

temperature 

1 g/cm3 EPA selected the density of water corresponding 

to water temperature based on the value 

provided in U.S. EPA, 2005b. 

k Von Karman’s constant 0.4 

unitless 

The von Karman constant is a known 

dimensionless constant used to describe the 

velocity profile of a turbulent fluid flow near a 

boundary. 

Kds Sediment-surface water 

partition coefficient 

Table C-4 The surface water partition coefficient describes 

the partitioning of a contaminant between 

sorbing material, in this case bottom sediment, 

and surface water. EPA identified U.S. EPA, 

2005 as the primary source for the metal-specific 

surface water partition coefficients. 

C-15
 
 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

Table C-2. Default Model Assumption Input Values 

Input Variable Description 

Assumed 

Value Assumption Rationale 

Kdsw Suspended sedimentsurface water partition 

coefficient 

Table C-4 The suspended sediment partition coefficient 

describes the partitioning of a contaminant 

between sorbing material, in this case suspended 

sediment, and surface water. EPA identified U.S. 

EPA, 2005 as the primary source for the metalspecific suspended sediment partition 

coefficients. 

Kdbs Bottom sediment-water 

partition coefficient 

Table C-4 The bottom sediment partition coefficient 

describes the partitioning of a contaminant 

between sorbing material, in this case bottom 

sediment, and surface water. EPA identified U.S. 

EPA, 2005 as the primary source for the metalspecific bed sediment partition coefficients. 

λ2 Dimensionless viscous 

sublayer thickness 

4 

unitless 

EPA selected the viscous sublayer thickness 

value based on the value provided in U.S. EPA, 

2005b. 

μw Viscosity of water 

corresponding to water 

temperature 

0.0169 

g/cm-s 

EPA selected the viscosity of water value based 

on the value provided in U.S. EPA, 2005b. 

HLC Henry’s Law Constant 0.0113 

atm-m3/mol 

Henry’s Law Constant is used in Equation C-18 

to estimate the receiving water concentration for 

volatile metals. Mercury is the only volatile 

metal included in the water quality model. 

Therefore, the assumed model default value is 

set to Henry’s Law Constant for mercury at 298 

°K. 

Thlc Temperature of Henry’s 

Law Constant 

298 The value 298 °K is the standard temperature 

value provided for Henry’s Law Constant. 

MW Molecular weight 200.59 

g/mol 

Molecular weight is used in Equation C-20 and 

Equation C-24 to estimate the receiving water 

concentration for volatile metals. Mercury is the 

only volatile metal included in the water quality 

model. Therefore, the assumed model default 

value is set to the molecular weight for mercury. 

CSCLsw Ecological benchmark for 

surface water 

Table C-7 U.S. EPA, 2009d and 2009e. 

Table C-3. Site-Specific Model Assumption Input Values 

Input Variable Description 

Assumed 

Value Data Source 

TSS Total suspended solids Table C-5 EPA used the geometric mean of the regional and 

national TSS concentrations determined as part of 

the CCW Risk Assessment [U.S. EPA, 2010b; 

Chapter 6 of U.S. EPA, 1999]. 

C-16
 
 

Appendix C—Water Quality Model Methodology 

Table C-3. Site-Specific Model Assumption Input Values 

Input Variable Description 

Assumed 

Value Data Source 

W10 Wind velocity 10 m above 

the water surface 

Table C-1 National Climatic Data Center national mean 

annual wind speed GIS coverage (downloaded 

05/12/2011 from 

http://hurricane.ncdc.noaa.gov/cgibin/climaps/climaps.pl?directive=quick_search&s 

ubrnum=). EPA selected, as an environmentally 

conservative estimate, the lower of the wind 

speed range values for the analysis. 

Ta Air temperature Table C-2 National Climatic Data Center national mean 

annual temperature GIS coverage (downloaded 

05/12/2011 from 

http://hurricane.ncdc.noaa.gov/cgibin/climaps/climaps.pl?directive=quick_search&s 

ubrnum=). EPA selected, as an environmentally 

conservative estimate, the lower of the air 

temperature range values for the analysis. 

Tw Temperature of the water 

body 

Table C-6 EPA used the regional surface temperatures 

determined as part of the CCW Risk Assessment 

[U.S. EPA, 2010b; Chapter 6 of U.S. EPA, 

1999b]. 

Figure C-1. National Climatic Data Center National Mean Annual Wind Speed 

C-17
 
Appendix C—Water Quality Model Methodology 

Figure C-2. National Climatic Data Center National Mean Annual Temperature
 

Table C-4. Surface Water Partition Coefficients
 

Pollutant 

Sediment-Surface Water 

Partition Coefficient (Kds) 

(mg/L) 

Suspended Sediment-Surface 

Water Partition Coefficient (Kdsw) 

(mg/L) 

Bottom Sediment-Pore 

Water Partition 

Coefficient (Kdbs) 

Arsenic 3.2 3.9 2.4 

Cadmium 2.7 4.9 3.3 

Chromium (VI) 0.8 4.2 1.7 

Copper 2.5 4.7 3.5 

Lead 3.7 5.7 4.6 

Mercury (II) 3.6 5.3 4.9 

Nickel 2.9 4.3 3.9 

Selenium (IV) 1.3 4.4 3.6 

Thallium 0.5 4.1 1.3 

Zinc 2.7 5.0 4.1 

Source: U.S. EPA, 2005. 

Table C-5. TSS Concentrations in Lakes and Rivers 

Hydrologic 

Region 

Number of 

Measurements 

Number of 

Annual Medians 

Annual Median TSS (mg/L) 

(log triangular distribution) 

Min Max 

Geometric 

Mean 

Weighted 

Geometric 

Mean 

1 9,007 33 3.2 40 8 6 

2 47,202 38 10 316 32 40 

3 43,395 36 6.3 79 25 25 

4 29,577 37 6.3 794 25 25 

5 39,900 38 4 100 25 25 

C-18
 
Appendix C—Water Quality Model Methodology 

Table C-5. TSS Concentrations in Lakes and Rivers 

Hydrologic 

Region 

Number of 

Measurements 

Number of 

Annual Medians 

Annual Median TSS (mg/L) 

(log triangular distribution) 

Min Max 

Geometric 

Mean 

Weighted 

Geometric 

Mean 

6 4,137 28 5 316 16 20 

7 34,494 37 32 1,585 63 100 

8 46,231 38 50 316 158 126 

9 3,254 35 13 3,162 32 63 

10 62,791 38 10 398 126 126 

11 48,969 38 25 794 200 126 

12 7,280 35 40 1,995 79 126 

13 13,974 37 32 79,433 200 398 

14 26,699 38 16 5,012 158 251 

15 9,162 37 20 19,953 200 398 

16 19,965 33 4 2,512 16 25 

17 173,136 37 2 316 6 10 

18 42,022 37 13 398 63 50 

Lakes 

(national) 4,360 99 1 398 25 25 

Source: U.S. EPA, 2010b; Legacy STORET database. 

Table C-6. Regional Surface Water Temperatures 

Hydrologic Region Climate Surface Water Temperature (°C) 

1 North 14 (Northern Median) 

2 North 16 

3 South 21 

4 North 14 

5 North 17 

6 South 18 

7 North 15 

8 South 20 

9 North 10 

10 North 13 

11 South 17 

12 South 21 

13 South 17 (Southern Median) 

14 South 9 

15 South 17 

16 South 9 

17 North 14 (Northern Median) 

18 South 15 

Source: U.S. EPA, 2010b; Legacy STORET database. 

C-19
 
 

 

 

 

Appendix C—Water Quality Model Methodology 

Table C-7. NRWQC and MCL Benchmarks 

Pollutant 

FW Acute 

NRWQC 

Benchmark a,b 

(mg/L) 

FW Chronic 

NRWQC 

Benchmark a,b 

(mg/L) 

HH WO 

NRWQC 

Benchmark a,b 

(mg/L) 

HH O 

NRWQC 

Benchmark a,b 

(mg/L) 

MCL 

Benchmark a,c 

(mg/L) 

Dissolved 

Arsenic 

0.34 0.15 - - -

Total 

Arsenic 

- - 0.000018 0.00014 0.01 

Dissolved 

Cadmium 

0.002 0.00025 - - -

Dissolved 

Chromium VI 

0.016 0.011 - - -

Total 

Chromium VI 

- - - - 0.1 

Dissolved 

Copper 

0.013 0.009 - - -

Total 

Copper 

- - 1.3 - 1.3 

Dissolved 

Lead 

0.065 0.0025 - - -

Dissolved 

Mercury 

0.0014 0.00077 - - -

Total 

Mercury 

- - - - 0.002 

Dissolved 

Nickel 

0.47 0.052 - - -

Total 

Nickel 

- - 0.61 4.6 -

Total 

Selenium 

- 0.005 0.17 4.2 0.05 

Total 

Thallium 

- - 0.00024 0.00047 -

Dissolved 

Zinc 

0.12 0.12 - - -

Total 

Zinc 

- - 7.4 26 -

Acronyms: MCL (Maximum Contaminant Level); NRQWC (National Recommended Water Quality Criteria). 

a – Designates instances where a benchmark does not exist for the pollutant or the benchmark is a secondary standard. 

b – National Recommended Water Quality Criteria. Washington, D.C. [U.S. EPA, 2009d]. Pollutant concentrations were 

compared to the freshwater (FW) acute and chronic NRWQC and the human health (HH) water and organisms (WO) and 

organisms only (O) NRWQC. 

c – National Primary Drinking Water Regulations. EPA 816-F-09-004. May. Washington, D.C. [U.S. EPA, 2009e]. 

Water Quality Model Methodology Limitations and Assumptions 

The limitations and assumptions in the water quality model are as follows: 

•	 The model is based on average annual loadings and effluent flows and does not 

consider temporal variability (e.g., seasonal differences, storm flows, low-flow 

events, catastrophic events). 

C-20
 
 

 

 

 

 

 

 

 

 

 

 

 

Appendix C—Water Quality Model Methodology 

•	 The model represents only the water body concentration within the immediate 

discharge zone (i.e., approximately 1 to 10 kilometers [km] from the outfall) and does 

not calculate metal concentrations in downstream waters. 

•	 The model does not take into consideration metal speciation within the receiving 

stream. This assumption/limitation is particularly relevant to the wildlife impact 

analysis as many of the ecological impacts are tied to a specific metal species. For 

example, inorganic arsenic is typically more toxic to aquatic life than organic arsenic. 

•	 The model assumes that equilibrium is quickly attained within the water body 

following discharge and is consistently maintained between the water column and 

surficial bed sediments. This assumption is especially significant regarding metal 

equilibrium within lakes and ponds. The model equations presented in Appendix C do 

not take into consideration the effects of currents, inversion, or temperature variations 

within the water column, but assume that the entire mass of the lake or pond is at 

equilibrium. The model does not account for the accumulation of metal 

concentrations in bottom sediments and pore water that occur over prolonged 

discharge periods. 

•	 The model assumes that metals dissolved or sorbed within the water column and bed 

sediments can be described by a partition coefficient. 

•	 The model assumes that metals sorbed to bed sediments are considered a net loss 

from the water body system. This assumes that bed sediments are not resuspended 

and deposited further downstream, but remain within the immediate discharge zone 

and do not further contribute to the dissolved or suspended sediment concentrations 

within the water body. 

•	 The model does not take into account ambient background metal concentrations or 

contributions from other point and nonpoint sources. 

•	 The metal loadings included in the model are not representative of the total metal 

loadings from steam electric power plants. There are several waste streams that are 

not included in the analysis (e.g., stormwater runoff, metal cleaning wastes, coal pile 

runoff). 

C-21
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix D—Wildlife Model Methodology 

APPENDIX D 

WILDLIFE MODEL METHODOLOGY 

This appendix presents the model equations, input values and pollutant benchmarks, and 

methodology limitations/assumptions for the wildlife model. Wildlife impacts include the 

following ecological receptors: 

•	 Aquatic and sediment organisms (amphibians, fish, invertebrates) in direct contact 

with receiving water and/or sediment in the immediate discharge zone of steam 

electric power plants; and 

•	 Wildlife (eagles and minks) 9 that consume fish from receiving waters in the 

immediate discharge zone of steam electric power plants. 

For the baseline conditions and five regulatory options (Options 1, 2, 3, 4, and 5), the 

U.S. Environmental Protection Agency (EPA) estimated pollutant concentrations in the receiving 

water and sediment using the water quality model (Appendix C). The wildlife model uses these 

concentrations as inputs. 

Model input requirements for the equations presented in Appendix D can be divided into 

five major categories: (1) input variable described by another equation; (2) site-specific input 

value (e.g., pollutant concentration from the water quality model); (3) default model assumption 

value (e.g., 15 percent of total mercury is dissolved in the water column as methylmercury); 

(4) pollutant-specific value; and (5) receptor-specific benchmark. The following tables in 

Appendix D describe the input requirements and data sources used in the wildlife model: 

•	 Table D-1. Chemical Stressor Concentration Limits (CSCLs) for Sediment Biota; 

•	 Table D-2. Bioconcentration Factors (BCFs) for Trophic Level 3 (T3) and Trophic 

Level 4 (T4) Fish; and 

•	 Table D-3. No Effect Hazard Concentration (NEHC) Benchmarks for Minks and Bald 

Eagles. 

Wildlife Model Equations 

EPA calculated the hazard quotient (HQ) (i.e., comparison of wildlife model value to 

benchmark) for aquatic organisms in direct contact with metals in the sediment and ingestion of 

contaminated fish for piscivorous wildlife (HQsed and HQI). An HQ of higher than one (i.e., 

pollutant concentration exceeds benchmark) indicates a potential impact to aquatic organisms or 

wildlife (i.e., minks or eagles). To calculate HQI, EPA estimated the metal concentration in fish 

(CfishT) for trophic level 3 and trophic level 4 fish. EPA used the equations presented below to 

calculate HQ values and fish tissue concentrations for arsenic, cadmium, chromium (VI), copper, 

lead, mercury (as methylmercury), nickel, selenium, thallium, and zinc. 

9 EPA selected eagles and minks to represent national-scale impacts from steam electric power plants because their habitats cover 

the entire United States (i.e., can be used for a national assessment). 

D-1
 
 

 

 

 

 

 

 

 

 

 

 

 

Appendix D—Wildlife Model Methodology 

Impact to Aquatic Life Receptors from Direct Contact with Sediment. Below is the equation for 

calculating the potential negative impact to aquatic organisms from direct contact with the 

sediment in receiving water bodies. 

EQUATION D-1 

Cbs HQ = sed CSCLsed 

where: 

HQsed = Hazard quotient for contact with sediment Output from Equation D-1 

Cbs = Total pollutant concentration in sediment 

(milligrams per liter [mg/L]) 

Water quality model output 

Equation C-5 

CSCLsed = Ecological benchmark for sediment 

(milligrams per kilograms [mg/kg]) 

Receptor-specific 

benchmark 

(see Table D-1) 

Assessment of Pollutant Bioconcentration in Fish. Equation D-2 calculates pollutant 

concentrations in fish for the evaluated pollutants, except for mercury. Because the more toxic 

form of mercury is methylmercury, EPA used Equation D-3 for this pollutant [U.S. EPA, 

2005b]. Equation D-3 estimates the concentration of methylmercury in fish tissue, as opposed to 

total mercury. 

EQUATION D-2 

CfishT = Cwc × BCFT 

EQUATION D-3 

CfishT = (0.15 × Cdw) × BCFT 

where: 

CfishT = Pollutant concentration in fish, where T 

represents trophic level T3 or T4 (mg/kg) 

Output from Equation D-2 

or Equation D-3 

Cwc = Total pollutant concentration in water (mg/L) Water quality model output 

Equation C-3 

Cdw = Dissolved pollutant concentration in water 

(mg/L) 

Water quality model output 

Equation C-4 

0.15 = Fraction of total mercury as dissolved 

methylmercury (unitless) 

Assumed value [U.S. EPA, 

2005b] 

BCFT = Bioconcentration factor for specified trophic 

level (liters per kilogram [L/kg]) 

Trophic-level-specific and 

pollutant-specific value 

(see Table D-2) 

Adverse Effects to Piscivorous Wildlife. To calculate the hazard to piscivorous wildlife (i.e., 

wildlife that consume fish), EPA used the following equation to calculate the potential for 

D-2
 
 

 

 

 

 

 

 

Appendix D—Wildlife Model Methodology 

adverse effects to minks consuming trophic level 3 fish and eagles consuming trophic level 4 

fish: 

EQUATION D-4 

CfishT HQI = NEHC 

where: 

HQI = Hazard quotient for ingestion of fish Output from Equation D-4 

CfishT = 

Concentration of pollutant in fish (mg/kg or 

micrograms per grams [μg/g]) for a specified 

trophic level (T3 or T4) 

Output from Equation D-2 

or Equation D-3 

NEHC = No effect hazard concentration (μg/g) Receptor- and pollutantspecific (see Table D-3) 

Wildlife Model Inputs 

Table D-1. CSCLs for Sediment Biota 

Pollutant in Wildlife 

Impact Assessment 

CSCL Benchmark 

Value (mg/kg) Notes (Source) 

Arsenic 10.798 (EPA 905-R96-008) 

Cadmium 0.583 (EPA 905-R96-008) 

Chromium VI 36.286 No benchmark for chromium VI. EPA used the total 

chromium benchmark, which may underestimate the 

impact to wildlife (EPA 905-R96-008). 

Copper 28.012 (EPA 905-R96-008) 

Lead 37 (EPA 905-R96-008) 

Mercury 0.174 (Arch ET&C 2000) 

Nickel 19.514 (EPA 905-R96-008) 

Selenium None identified EPA could not complete the analysis for this pollutant – 

Thallium None identified no benchmark for comparison. 

Zinc, total 98 (EPA 905-R96-008) 

Source: NOAA, 2008. 

Table D-2. BCFs for Trophic Level 3 and 4 Fish 

Pollutant 

BCF Value for 

Trophic Level 3 

(T3) Fish (L/kg) 

BCF Value for 

Trophic Level 4 

(T4) Fish Value 

(L/kg) Comment Source 

Arsenic total 4.00E+00 4.00E+00 Barrows, et al., 1980 

Cadmium 2.70E+02 2.70E+02 Kumada et al., 1972 

Chromium VI 6.00E-01 6.00E-01 Stephan, 1993 

Copper 0.00E+00 0.00E+00 T4 filet value used for T3 Stephan, 1993 

Lead 4.60E+01 4.60E+01 Stephan, 1993 

Mercury 1.60E+06 6.80E+06 U.S. EPA, 1997a 

Nickel 0.8 0.8 Soluble salts Stephan, 1993 

D-3
 
 

 

 

 

 

 

 

 

 

 

 

Appendix D—Wildlife Model Methodology 

Table D-2. BCFs for Trophic Level 3 and 4 Fish 

Pollutant 

BCF Value for 

Trophic Level 3 

(T3) Fish (L/kg) 

BCF Value for 

Trophic Level 4 

(T4) Fish Value 

(L/kg) Comment Source 

Selenium 4.90E+02 1.70E+03 Lemly, 1985a 

Thallium 3.40E+01 1.30E+02 Barrows et al., 1980 and 

Stephan, 1993 

Zinc 3.50E+02 3.50E+02 Murphy et al., 1978 

Table D-3. NEHC Values for Mink and Bald Eagles 

Pollutant in Wildlife 

ImpactAssessment 

NEHC Benchmark 

Value for Mink 

(T3 Fish) 

(μg/g) 

NEHC Benchmark 

Value for Eagle 

(T4 Fish) 

(μg/g) Notes 

Arsenic, total 7.65 22.4 

Cadmium, total 5.66 14.7 

Chromium VI 17.7 26.6 No benchmark for chromium VI. EPA 

used the total chromium benchmark, 

which may underestimate the impact to 

wildlife. 

Copper, total 41.2 40.5 

Lead, total 34.6 16.3 

Methylmercury 0.37 0.5 No benchmark for methylmercury. EPA 

used the total mercury benchmark, which 

may underestimate the impact to wildlife. 

Nickel, total 12.5 67.1 

Selenium, total 1.13 4 

Thallium, total None identified None identified EPA could not complete the analysis for 

this pollutant – no benchmark for 

comparison. 

Zinc, total 904 145 

Source: USGS, 2008. 

Wildlife Model Methodology Limitations and Assumptions 

EPA was required to make assumptions about various inputs, resulting in limitations with 

respect to model output and interpretation. Variability occurs from heterogeneous characteristics, 

such as body weight differences within a population or the contaminant levels in the 

environment. Uncertainty represents a lack of knowledge about factors such as the adverse 

effects from exposure to pollutants. The assumptions and limitations of the wildlife model 

include the following: 

•	 Additive Risks Across Pathways. The wildlife model described above does not 

consider additive risks across pathways. For example, the modeled impacts to wildlife 

from ingesting contaminated fish does not consider the risk from direct contact with 

surface water. The receptors chosen for the wildlife ingestion model, mink and eagle, 

do not spend large amounts of time in contact with the surface water; therefore, not 

including the impact of direct contact with surface water should only minimally 

D-4
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix D—Wildlife Model Methodology 

underestimate the impacts. In addition, the wildlife model does not consider the 

impact from water ingestion. Because many of the pollutants considered in this 

analysis are bioaccumulative in nature, the model considers only ingestion of the food 

source since it is likely the dose from the food source dominates the dose from water 

ingestion. 

•	 Receptor Populations Evaluated. EPA considered the limitations and made multiple 

assumptions in choosing receptor populations to evaluate. First, EPA assumed that, 

because this is a national model, the receptor species and receiving water occur 

together (i.e., all receiving waters are habitat for the receptor species even though that 

may not always be the case). In addition, due to the scope of the project, EPA 

considered a limited number of species for use as receptors. For the assessment of the 

impacts to aquatic life, EPA chose to use the sediment CSCL values from its 

Assessment and Remediation of Contaminated Sediments (ARCS) Program 

Guidelines where available. The ARCS Program Guidelines did not include a 

mercury CSCL; therefore, EPA chose to use the benchmark from Canada’s Interim 

Sediment Quality Guidelines (ISQGs) [NOAA, 2008]. For the wildlife receptors, 

EPA chose minks and eagles due to their national distribution and data available to 

conduct the analysis [USGS, 2008]. By choosing a limited number of species, the 

model inherently excludes the impacts to critical assessment endpoints such as 

threatened and endangered species. EPA attempts to address this limitation in the 

impact assessment by presenting a proximity analysis of steam electric power plants 

to habitats of threatened and endangered species (see Section 3.4.3 of this report). 

•	 Bioavailability and Speciation of Pollutants. Each model assumes that all forms of a 

pollutant are equally bioavailable to ecological receptors. Therefore, data inputs for 

the wildlife model include total metal in the water column (i.e., dissolved plus 

particles sorbed to suspended sediment) or sediment concentration for all pollutants 

analyzed, except where noted. In addition, some pollutant forms are more toxic to 

organisms, such as various forms of arsenic. While different forms of arsenic exist in 

the water column, it is not possible to determine the percentages of each due to the 

complexities of the chemistry of a particular water body. Because of bioavailability 

and metal speciation assumptions made for the wildlife impact assessment, the impact 

to receptors may be over- or underestimated. 

•	 Indirect Ecological Effects. The wildlife model does not consider indirect ecological 

effects, such as depletion of food sources. Such indirect effects are difficult to assess 

and are thought to have minimal impact on some wildlife species because the 

impacted receiving water is only a small portion of the species’ habitat. In addition, 

many species will move into other areas in search of prey if food sources in their 

current habitat decline. 

•	 Full Mixing Effects for Receiving Water. The water quality model assumes that the 

receiving water body is fully mixed. In reality, the water in lakes might stratify, 

especially if they are deep enough. Chemical speciation, mostly based on pH, varies 

by strata; for example, if the hypolimnion (i.e., lowest stratum of a lake) has a much 

lower pH than the epilimnion (i.e., upper stratum), the concentration or speciation of 

many metals may vary between the two layers. Therefore, bottom-dwelling organisms 

D-5
 
 

 

 

 

 

 

Appendix D—Wildlife Model Methodology 

would be exposed to different species and concentrations of metals. Due to the 

complexity of these relationships and necessity for site-specific data, none of the 

impact analyses considered stratification of receiving waters. 

•	 Multiple Pollutant Exposures. According to EPA’s Steam Electric Power 

Generating Point Source Category: Final Detailed Study Report [U.S. EPA, 2009b], 

receptors will be exposed to multiple constituents simultaneously. However, the 

wildlife model examines the impact of individual pollutants to receptors and does not 

take into account how the interaction of multiple pollutants impacts the adverse 

effects to receptors. For example, EPA did not consider the impact of mercury on the 

uptake or toxicity of selenium. There is evidence in the literature that these two 

compounds interact with each other in the environment and may decrease the level of 

impact on a receptor; conversely, the interaction of other pollutants may increase the 

impact to a receptor. However, because benchmarks are based on the toxicity of 

individual chemicals, and the relationships between chemicals are complex, it is 

beyond the scope of this analysis to include the effects of multiple pollutant 

interactions on receptors. 

•	 Ecological Benchmarks. EPA used ecological benchmarks as described above to 

determine impacts to aquatic organisms from direct contact with contaminated 

sediment. The benchmarks represent the threshold effect level (TEL) for H azteca.10 

If an organism ingests chemical concentration above the TEL, some effect (or 

response) will be produced. If the concentration ingested is below the TEL, no effect 

(or response) will occur. The TEL represents the concentration of a chemical that 

would result in “no effect,” therefore the results presented in EA report are a more 

environmentally protective impact estimate [USGS, 2008]. 

10 The mercury CSCL does not specify the aquatic organism [NOAA, 2008]. 

D-6
 
 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix E—Human Health Model Methodology 

APPENDIX E 

HUMAN HEALTH MODEL METHODOLOGY 

This appendix presents the model equations, input values and benchmarks, and 

methodology limitations/assumptions for the human health model. Human health impacts 

include the following receptor groups: 

•	 Child cohorts (recreational) that consume fish exposed to pollutants as a result of 

discharges from steam electric power plants; 

•	 Child cohorts (subsistence) that consume fish exposed to pollutants as a result of 

discharges from steam electric power plants; 

•	 Adult cohorts (recreational) that consume fish exposed to pollutants as a result of 

discharges from steam electric power plants; and 

•	 Adult cohorts (subsistence) that consume fish exposed to pollutants as a result of 

discharges from steam electric power plants. 

For the baseline conditions and five regulatory options (Options 1, 2, 3, 4, and 5), the 

U.S. Environmental Protection Agency (EPA) estimated pollutant concentrations in fish tissue 

using the wildlife model (Appendix D). The human health model uses these concentrations as 

inputs. 

Model input requirements for the equations presented in Appendix E can be divided into 

five major categories: (1) input variable described by another equation; (2) site-specific input 

value (i.e., pollutant concentration in fish tissue); (3) default model assumption value (e.g., 

fraction of trophic level 3 [T3] and trophic level 4 [T4] fish intake by receptor); (4) receptor 

cohort-specific value (e.g., body weight [BW] and fish consumption rate); and (5) pollutantspecific value (i.e., reference dose [RfD] for noncancer effects and cancer slope factor, CSF). 

The following tables in Appendix E describe the input requirements and data sources used in the 

human health model: 

•	 Table E-1. Calculation of FT3 and FT4. 

•	 Table E-2. Default Input Values for the Human Health Model; 

•	 Table E-3. Receptor Cohort-Specific input Values for the Human Health Model; and 

•	 Table E-4. Reference Doses and Cancer Slope Factors for Pollutants in the Human 

Health Model. 

Human Health Model Equations 

EPA calculated the hazard quotient (HQ) (i.e., comparison of human health model value 

to benchmark) for ingestion of contaminated fish by multiple cohorts. An HQ of higher than one 

(i.e., pollutant dosage or cancer risk factor exceeds benchmark) indicates a potential impact to 

the human cohort. To calculate the HQ, EPA estimated the metal concentrations in fish fillets 

consumed by humans (i.e., dose), using an assumed consumption ratio of T3 and T4 fish and 

E-1
 
 

 

 

 

 

 

 

 

 

 

Appendix E—Human Health Model Methodology 

pollutant concentrations in fish. EPA also calculated a lifetime excess cancer risk (LECR) for 

each cohort. This study used 1-in-1,000,000 cancer risk as an acceptable risk threshold when 

evaluating exposures associated with fish consumption. EPA used the equations presented below 

to calculate HQ values (noncancer impact) for arsenic, cadmium, chromium (VI), copper, lead, 

mercury, nickel, selenium, thallium, and zinc and LECR values for arsenic. 

EQUATION E-1 

Cfish_fillet = FT3 × CfishT3F + FT4 × CfishT4F 

where: 

Cfish_fillet = Average fish fillet concentration ingested by 

humans (milligrams per kilograms [mg/kg]) Output from Equation E-1 

CfishT3F = 

Concentration of contaminant in fish at 

trophic level 3 (mg/kg) 

Wildlife model output 

Equation D-2 and Equation 

D-3 

CfishT4F = 

Concentration of contaminant in fish at 

trophic level 4 (mg/kg) 

Wildlife model output 

Equation D-2 and Equation 

D-3 

FT3 = Fraction of trophic level 3 fish intake 

(unitless) 

Assumed value of 0.36 

(see calculation below) 

FT4 = Fraction of trophic level 4 fish intake 

(unitless) 

Assumed value of 0.64 

(see calculation below) 

Calculation of FT3 and FT4 

To determine the fraction of T3 and T4 fish intake for humans, EPA started with the data 

presented in the 2011 Emissions Factor Handbook, Table 10-74 [U.S. EPA, 2011b]. EPA then 

completed the following analysis: 

1. Assigned trophic levels to fish if not already listed in the table. 

2. Sum the quantities of fish consumed by trophic level. 

3. Determine fraction of fish consumed at each trophic level. 

Table E-1 documents the data and analysis performed. EPA chose to use the factors for fish 

intake that corresponded to rivers and streams; this is the most common receiving water source 

in the EA model. 

E-2
 
 

 

 

 

 

 

Appendix E—Human Health Model Methodology 

Table E-1. Calculation of FT3 and FT4 

Species 

Trophic 

Level 

Ice Fishing Lakes and Ponds Rivers and Streams 

Quantity 

Consumed 

Grams 

(x103

) 

Consumed 

Quantity 

Consumed 

Grams 

(x103

) 

Consumed 

Quantity 

Consumed 

Grams 

(x103

) 

Consumed 

Landlocked 

salmon 4 832 290 928 340 305 120 

Atlantic salmon 4 3 1.1 33 9.9 17 11 

Togue (Lake 

trout) 4 483 200 459 160 33 2.7 

Brook trout 4 1,309 100 3,294 210 10,185 420 

Brown trout 4 275 54 375 56 338 23 

Yellow perch 3 235 9.1 1,649 52 188 7.4 

White perch 3 2,544 160 6,540 380 3,013 180 

Bass 

(smallmouth 

and largemouth) 4 474 120 73 5.9 787 130 

Pickerel 3 1,091 180 553 91 303 45 

Lake whitefish 3 111 20 558 13 55 2.7 

Hornpout 

(Catfish and 

bullheads) 3 47 8.2 1,291 100 180 7.8 

Bottom fish 

(Suckers, carp 

and sturgeon) 3 50 81 62 22 100 6.7 

Chub 3 0 0 252 35 219 130 

Smelt 3 7,808 150 428 4.9 4,269 37 

Other 4 201 210 90 110 54 45 

TOTALS 15,463 1,583 16,587 1,590 20,046 1,168 

Totals by Trophic Level: 

T3 

Total 11,886 608 11,333 698 8,327 417 

T4 

Total 3376 765.1 5162 781.8 11665 751.7 

Calculation of Factors by Trophic Level 

T3 

Factor 0.77 0.38 0.68 0.44 0.42 0.36 

T4 

Factor 0.22 0.48 0.31 0.49 0.58 0.64 

Source: U.S. EPA, 2011b.
 

Bold indicates factors selected for the human health model.
 

The next equation calculates the daily intake of contaminant from fish ingestion, also 

called the average daily dose (ADD). Based on the ADD, the human health model calculates the 

lifetime average daily dose (LADD) in Equation E-3. 

E-3
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix E—Human Health Model Methodology 

EQUATION E-2 

Cfish_fillet × CRfish × Ffish ADD = 1,000 × BW 

where: 

ADD = Daily dose of pollutant from fish ingestion 

(mg/kg BW/day) Output from Equation E-2 

Cfish_fillet = 

Average fish fillet concentration ingested by 

humans (mg/kg) 11 Output from Equation E-1 

CRfish = Consumption rate of fish (g ww/day) 

Age-cohort-specific 

assumed value 

(see Table E-3) 

Ffish = 

Fraction of fish intake from contaminated 

source 

Assumed value of 1 

1,000 = Conversion factor (grams per kilograms 

[g/kg]) 

BW = Body weight (kg) 

Age-cohort-specific 

assumed value 

(see Table E-3) 

EQUATION E-3 

LADD = 

ADD × ED × EF 

AT × 365 

where: 

LADD = Lifetime average daily dose (mg/kg BW/day) Output from Equation E-3 

ADD = Daily dose of pollutant from fish ingestion 

(mg/kg BW/day) Output from Equation E-2 

ED = Exposure duration for oral ingestion (yr) 12 

Age-cohort-specific 

assumed value 

(see Table E-3) 

EF = Exposure frequency (days/yr) Assumed value of 350 13 

11 Based on literature review (including EPA and Agency for Toxic Substances and Disease Registry (ATSDR) references), 

arsenic in fish is mostly in the organic form and not harmful to humans. The inorganic form of arsenic is harmful to humans; 

EPA’s 1997 document, Arsenic and Fish Consumption, reported the inorganic arsenic concentration in fish is between 0.4 – 4 

percent of the total arsenic accumulating in fish. EPA estimated the inorganic arsenic concentration in fish by assuming 4 percent 

of the total arsenic is inorganic. EPA used the inorganic arsenic concentration in fish to determine human health impacts. The 

human health model multiplies the Cfish_fillet concentration by 4 percent for arsenic (converting concentration from total to 

inorganic). 

12 The model calculates the LADD of arsenic for each child cohort (six recreational and six subsistence) and for each adult cohort 

(one recreational and one subsistence). EPA assumed the exposure durations (ED) for use in the LADD calculation is equal to the 

length of time in that cohort range. Therefore the exposure duration for the six-child cohorts (youngest to oldest) are 1, 1, 3, 5, 5, 

and 5 years, respectively. For the adult cohort, the exposure duration is 49 years. 

13 Exposure frequency was set to 350 days per year, assuming residents take an average of two weeks of vacation away from their 

homes each year. 

E-4
 
 

 

 

 

 

Appendix E—Human Health Model Methodology 

AT = Averaging time (yr) Assumed value of 70 

[U.S. EPA, 2011b] 

365 = Conversion factor (days/yr) 

Calculated Impacts from Noncarcinogenic Pollutants 

EQUATION E-4 

ADD 

HQ = RfD 

where: 

HQ = Hazard quotient Output from Equation E-4 

ADD = Daily dose of pollutant from fish ingestion 

(mg/kg BW/day) Output from Equation E-2 

RfD = Noncancer reference dose (mg/kg BW/day) Chemical-specific value 

(see Table E-4) 

Calculated Risk from Carcinogenic Pollutants 

The risk from cancer-causing pollutants is expressed in terms of lifetime excess cancer risk 

(LECR). 

EQUATION E-5 

LECR = LADD × CSF 

where: 

LECR = Lifetime excess cancer risk Output from Equation E-5 

LADD = Lifetime average daily dose (mg/kg BW/d) Output from Equation E-3 

CSF = Cancer slope factor (mg/kg BW/day)-1 

Chemical-specific assumed 

value 

(see Table E-4) 

Human Health Model Inputs 

Table E-2. Default Input Values for the Human Health Model 

Input 

Variable Description Default Value Data Source 

FT3 Fraction of trophic level 3 fish intake 0.36 U.S. EPA, 2011b 

FT4 Fraction of trophic level 4 fish intake 0.64 U.S. EPA, 2011b 

Ffish Fraction of fish intake from contaminated 

source 

1 Assumed value. 

EF Exposure frequency (days/yr) 350 Assumed value. 

E-5
 
 

 

 

 

 

 

 

Appendix E—Human Health Model Methodology 

Table E-2. Default Input Values for the Human Health Model 

Input 

Variable Description Default Value Data Source 

AT Averaging time (yr) 70 U.S. EPA, 2011b 

Table E-3. Receptor-Cohort-Specific Input Values for the Human Health Model 

Receptor Cohort a 

Body Weight 

(kg) a 

Consumption Rate 

(g/day) b 

Exposure Duration 

(years) 

Child Recreational 

Fisher 

1 to <2 years 11.4 2.5 (b) 1 

2 to <3 years 13.8 3 (b) 1 

3 to <6 years 18.6 3.5 (b) 3 

6 to <11 years 31.8 5.1 (b) 5 

11 to <16 years 56.8 5.7 (b) 5 

16 to <21 years 71.6 7.2 (b) 5 

Child Subsistence 

Fisher 

1 to <2 years 11.4 13.7 (b) 1 

2 to <3 years 13.8 16.6 (b) 1 

3 to <6 years 18.6 26 (b) 3 

6 to <11 years 31.8 35 (b) 5 

11 to <16 years 56.8 39.8 (b) 5 

16 to <21 years 71.6 50.1 (b) 5 

Adult Recreational Fisher 80 20 (c) 49 

Adult Subsistence Fisher 80 88 (d) 49 

Acronyms: g/day (grams per day); kg (kilograms).
 

a – The child cohort age ranges correspond to the ranges provided in the 2008 Child-Specific Exposure Factor Handbook (EFH)
 

for body weights [U.S. EPA, 2008a].
 

b – EPA determined consumption rates for child cohorts using data from Table 10-1 (Recommend Per Capita and ConsumerOnly Values for Fish Intake) for finfish consumption [U.S. EPA, 2011b]. EPA used the mean values for recreational fishers and
 

95th percentile values for subsistence fishers. EPA converted the listed consumption rate (g/kg-day) to g/day by multiplying by
 

mean body weight for each cohort as listed in U.S. EPA, 2008 [ERG, 2013m]. Fish intake rates provided in the reference [U.S.
 

EPA, 2011b] are recommended for the general population; the selection of consumption rates for exposure assessment purposes
 

may vary depending on the exposure scenarios being evaluated.
 

c – EPA determined consumption rates for adult recreational fishers using data from Table 10-5 of U.S. EPA, 2011b. EPA used
 

the mean values for freshwater fish consumption (g/day) based on location and population groups. EPA used consumption rates
 

for all respondents and calculated a median value to use in the model [ERG, 2013m]. U.S. EPA, 2011b does not provide
 

recommended values for fish consumption, but does present available data for certain geographic areas. Assessors may use these 

data, if appropriate, to the scenarios and populations being assessed. EPA used the mean consumption rate across the geogprahic
 

areas to represent a central-tendency value for adult fishers across the United States. A fraction of the adult fisher population may 

experience higher consumption rates as evidenced by the 95th percentile values presented in Table 10-5.
 

d – EPA determined consumption rates for adult subsistence fishers using data from Table 10-6 of U.S. EPA, 2011b. EPA used
 

the mean values for fish consumption based on location/name of Native American tribe. EPA used values listed for adults and
 

converted the data into consumption rates (units of g/day) assuming an adult body weight of 80 kg, as provided in Section 8.1 of
 

U.S. EPA, 2011b. EPA then calculated a median value to use in the model [ERG, 2013m]. U.S. EPA, 2011b does not provide 

recommended values for fish consumption but does present available data for certain geographic areas. Assessors may use these 

data, if appropriate, to the scenarios and populations being assessed. EPA used the mean consumption rate across the geogprahic 

areas to represent a central-tendency value for adult fishers across the United States. A fraction of the adult fisher population may 

experience higher consumption rates as evidenced by the 95th percentile values presented in Table 10-6. 

E-6
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix E—Human Health Model Methodology 

Table E-4. RfDs and Cancer Slope Factors (CSF) for Pollutants in the Human Health 

Model
 

Pollutant in Human Health 

Impact Assessment 

RfD 

(mg/kg-day) 

CSF 

(mg/kg-day) -1 Notes a 

Arsenic, inorganic 3.00E-04 1.50E+00 RfD and CSF for drinking water ingestion 

Cadmium, total 1.00E-03 RfD for food consumption 

Chromium VI 3.00E-03 RfD for drinking water ingestion 

Copper 1.00E-02 Used the intermediate oral minimal risk 

level (MRL) as the reference dose 

[ATSDR, 2010a] 

Lead, total None available 

Methylmercury 1.00E-04 RfD for fish consumption only 

Nickel, total 2.00E-02 RfD for soluble salts; used for food 

consumption 

Selenium, total 5.00E-03 RfD for food consumption 

Thallium, total 1.00E-05 Used value cited in U.S. EPA, 2010 for 

thallium chloride as the reference dose; 

used for chronic oral exposure 

Zinc, total 3.00E-01 RfD for food consumption 

a – References include ATSDR, 2010 for copper; U.S. EPA, 2010 for thallium, and U.S. EPA, 2011c for all other 

pollutants. 

Human Health Model Limitations and Assumptions 

The human health model limitations and assumptions include the following: 

•	 Additive Risks Across Pathways. The human health model does not consider additive 

risks across pathways. For example, the model assumes that the human population 

consuming the fish is not also ingesting contaminated drinking water. Exposures from 

fish consumption and drinking water are likely to occur over different time frames 

(because of ground water travel) and may involve different receptors (e.g., a resident 

near a receiving water exposed to ground water contamination may not be a 

recreational fisher). Similarly, the model assumes that these populations are not 

coming in direct contact with contaminated surface water or sediment through 

recreation. Based on these assumptions, the model may underestimate total risk to 

human health from combustion wastewater. 

•	 Bioavailability and Speciation of Pollutants. The assumptions listed for the wildlife 

model in Appendix D apply to pollutant concentrations modeled in fish and therefore 

impact the human health impact assessment. 

•	 Full Mixing Effects for Receiving Water. The assumptions listed for the wildlife 

model in Appendix D apply to pollutant concentrations modeled in fish and therefore 

impact the human health impact assessment. 

•	 Multiple Pollutant Exposures. According to previous analyses and literature 

reviewed [U.S. EPA, 2009b], people who ingest fish from impacted waters will be 

exposed to multiple pollutants from the waste streams evaluated. However, the model 

evaluates each pollutant individually. Such an approach does not account for 

E-7
 
 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix E—Human Health Model Methodology 

interactive effects that might be associated with exposures to mixtures. For example, 

some pollutants may have a higher risk when consumed together because of their 

interaction, whereas other pollutants may have less impact on human health when 

consumed together. Due to the complexity of these interactions and because 

benchmarks are based on the toxicity of individual chemicals, it is not possible to 

examine these synergistic effects in this analysis. Based on this limitation, risks of 

pollutants may be over- or underestimated. 

•	 Human Exposure Factors. Individual exposure factors, such as ingestion rate, body 

weight, and exposure duration, are variable due to the physical characteristics, 

activities, and behavior of the individual. EPA used the most current data regarding 

exposure assumptions, and these values represent EPA’s current guidance on 

exposure data [U.S. EPA, 2008a; U.S. EPA, 2011b]. 

•	 Human Health Benchmarks. Uncertainties generally associated with human health 

benchmarks are discussed in detail in EPA’s Guidelines for Carcinogen Risk 

Assessment [U.S. EPA, 2005c] and Integrated Risk Information System (IRIS) [U.S. 

EPA, 2011c]. IRIS defines the RfD as “an estimate (with uncertainty spanning 

perhaps an order of magnitude) of a daily oral exposure to the human population 

(including sensitive subgroups) that is likely to be without an appreciable threat of 

deleterious effects during a lifetime.” RfDs are typically based on an assumption of 

lifetime exposure and may not be appropriate when applied to less-than-lifetime 

exposure situations [U.S. EPA, 2011c]. The cancer slope factor is an estimate of the 

human cancer risk per milligram of chemical per kilogram body weight per day. To 

calculate the lifetime average daily dose (LADD) used for the cancer impact 

assessment, EPA used the time in the cohort group (i.e., 1, 3, or 5 years depending on 

child cohort and 49 years for adult cohort) as the exposure duration (ED). The ED is 

the length of time exposure occurs at the concentration. This analysis may over- or 

under-estimate the cancer risk if exposure is shorter than or longer than the ED, 

respectively. LADDs are appropriate when developing screening-level estimates; 

however, EPA recommends calculating that risk by integrating exposures or risks 

through all life stages (e.g. chronic exposure for a child may occur across cohorts) 

[U.S. EPA, 2011b]. 

E-8
 
 

Appendix F—Additional Model Results 

APPENDIX F 

ADDITIONAL MODEL RESULTS 

Table F-1. Number and Percentage of Immediate Receiving Waters that Exceeded a
 

Criterion by Pollutant and Criteria Type at Baseline Pollutant Loadings
 

Pollutant 

Number of Immediate Receiving Waters that Exceeded a Criterion a 

Freshwater 

Acute 

NRWQC 

Freshwater 

Chronic 

NRWQC 

Human 

Health 

Water and 

Organism 

NRWQC 

Human 

Health 

Organism 

Only 

NRWQC 

Drinking 

Water 

MCL 

Total Receiving Waters b 

Number 

Exceeding 

Percentage 

Exceeding 

Dissolved 

Arsenic 

6 7 - - - 7 2% 

Total Arsenic - - 147 96 19 147 49% 

Dissolved 

Cadmium 

30 65 - - - 65 22% 

Total 

Cadmium 

- - - - 22 22 7% 

Dissolved 

Chromium VI 

7 8 - - - 8 3% 

Total 

Chromium VI 

- - - - 2 2 1% 

Dissolved 

Copper 

18 21 - - - 21 7% 

Total Copper - - 1 - 1 1 <1% 

Dissolved 

Lead 

9 31 - - - 31 10% 

Total Lead - - - - 16 16 5% 

Dissolved 

Mercury 

2 2 - - - 2 <1% 

Total Mercury - - - - 0 0 0% 

Dissolved 

Nickel 

8 24 - - - 24 8% 

Total Nickel - - 7 0 - 7 2% 

Total 

Selenium 

- 42 13 0 20 42 14% 

Total Thallium - - 82 74 55 82 28% 

Dissolved Zinc 16 16 - - - 16 5% 

Total Zinc - - 1 0 - 1 <1% 

Source: ERG, 2013h; ERG, 2013l. 

Acronyms: MCL (Maximum Contaminant Level); NRWQC (National Recommended Water Quality Criteria). 

a – A total of 297 immediate receiving waters (261 rivers and streams; 36 lakes, ponds, and reservoirs) were included in the water 

quality model. 

b – These values are the sum and percentage of rivers, streams, lakes, ponds, and reservoirs impacted. 

F-1
 
 

Figure F-1. Baseline Total Arsenic Concentration in the 

Immediate Receiving Water
 

Number of Plant Receiving Waters 

120 

110 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

Total Arsenic Concentration in Receiving Water (mg/L) 

 

 

 

 

 

 

Appendix F—Additional Model Results 

Table F-2. Total Arsenic Concentration (mg/L) in the Immediate Receiving
 

Water by Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 8.21E-08 8.11E-08 8.12E-08 a 3.71E-08 0.00E+00 0.00E+00 

25th 1.71E-06 1.71E-06 1.71E-06 6.87E-07 0.00E+00 0.00E+00 

50th 1.72E-05 1.72E-05 1.72E-05 5.64E-06 4.82E-08 5.90E-08 b 

75th 5.86E-04 5.70E-04 5.70E-04 3.85E-04 2.88E-06 2.79E-06 

95th 1.70E-02 1.70E-02 1.70E-02 8.77E-03 4.22E-04 3.36E-04 

Max 2.22E+00 2.22E+00 2.22E+00 2.22E+00 1.39E+00 1.39E+00 

a – Total pollutant removals for Regulatory Option 2 are greater than Regulatory Option 1; however, for 

certain pollutants the reductions estimated under Regulatory Option 2 are slightly less those reported under 

Regulatory Option 1. 

b– Under Regulatory Option 4, some plants that discharge both leachate and flue gas desulfurization (FGD) 

treat the two waste streams together in a chemical precipitation plus biological treatment system. Under 

Regulatory Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, 

for some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed Effluent 

Limitation Guidelines and Standards for the Steam Electric Generating Point Source Category Report for 

further discussion of the regulatory option loadings. 

F-2
 
 

 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Cadmium Concentration in Receiving Water (mg/L) 

Figure F-2. Baseline Total Cadmium Concentration in the 

Immediate Receiving Water 

Table F-3. Total Cadmium Concentration (mg/L) in the Immediate Receiving
 

Water by Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 3.47E-08 2.12E-08 2.07E-08 1.01E-08 0.00E+00 0.00E+00 

25th 7.41E-07 4.51E-07 4.45E-07 2.57E-07 0.00E+00 0.00E+00 

50th 6.10E-06 4.49E-06 4.29E-06 2.16E-06 2.68E-08 4.23E-08 a 

75th 1.98E-04 9.35E-05 9.29E-05 5.71E-05 1.04E-06 1.51E-06 a 

95th 8.95E-03 4.56E-03 4.49E-03 2.42E-03 2.07E-04 1.98E-04 

Max 2.77E-01 2.77E-01 2.77E-01 1.81E-01 1.81E-01 1.81E-01 

a– Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams 

together in a chemical precipitation plus biological treatment system. Under Regulatory Option 5 for these 

plants, leachate is only treated with a chemical precipitation system; therefore, for some immediate receiving 

waters the metal concentrations will increase under Regulatory Option 5 compared to Regulatory Option 4. 

See the Incremental Costs and Pollutant Removals for Proposed Effluent Limitation Guidelines and Standards 

for the Steam Electric Generating Point Source Category Report for further discussion of the regulatory option 

loadings. 

F-3
 
 

Figure F-3. Baseline Total Chromium VI Concentration in the 
 

Immediate Receiving Water
 

Number of Plant Receiving Waters 120 

110 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

Total Chromium VI Concentration in Receiving Water (mg/L) 

Appendix F—Additional Model Results 

Table F-4. Total Chromium VI Concentration (mg/L) in the Immediate 

Receiving Water by Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 

25th 1.01E-07 1.01E-07 8.35E-08 5.75E-08 0.00E+00 0.00E+00 

50th 1.01E-06 1.01E-06 9.90E-07 3.97E-07 0.00E+00 0.00E+00 

75th 2.30E-05 2.30E-05 2.29E-05 6.89E-06 0.00E+00 0.00E+00 

95th 1.95E-03 1.95E-03 1.80E-03 7.05E-04 2.63E-06 1.98E-07 

Max 4.00E-01 4.00E-01 4.00E-01 2.62E-01 2.62E-01 2.62E-01 

F-4
 
 

 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120 

Number of Plant Receiving Waters 

Total Copper Concentration in Receiving Water (mg/L) 

Figure F-4. Baseline Total Copper Concentration in the Immediate 

Receiving Water 

Table F-5. Total Copper Concentration (mg/L) in the Immediate Receiving 

Water by Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 5.71E-08 4.80E-08 4.98E-08 a 3.68E-08 0.00E+00 0.00E+00 

25th 1.91E-06 1.57E-06 1.58E-06 a 9.21E-07 0.00E+00 0.00E+00 

50th 1.66E-05 1.24E-05 1.25E-05 a 6.36E-06 2.87E-08 4.50E-08 b 

75th 3.26E-04 2.73E-04 2.90E-04 a 1.92E-04 1.87E-06 2.16E-06 b 

95th 1.99E-02 1.39E-02 1.39E-02 7.31E-03 1.70E-04 1.69E-04 

Max 1.32E+00 1.32E+00 1.32E+00 8.61E-01 8.61E-01 8.61E-01 

a – Total pollutant removals for Regulatory Option 2 are greater than Regulatory Option 1; however, for 

certain pollutants the reductions estimated under Regulatory Option 2 are slightly less those reported under 

Regulatory Option 1. 

b– Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams 

together in a chemical precipitation plus biological treatment system. Under Regulatory Option 5 for these 

plants, leachate is only treated with a chemical precipitation system; therefore, for some immediate receiving 

waters the metal concentrations will increase under Regulatory Option 5 compared to Regulatory Option 4. 

See the Incremental Costs and Pollutant Removals for Proposed Effluent Limitation Guidelines and Standards 

for the Steam Electric Generating Point Source Category Report for further discussion of the regulatory option 

loadings. 

F-5
 
 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Lead Concentration in Receiving Water (mg/L) 

Figure F-5. Baseline Total Lead Concentration in the Immediate 

Receiving Water 

Table F-6. Total Lead Concentration (mg/L) in the Immediate Receiving Water 

by Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 3.32E-08 3.00E-08 3.00E-08 2.03E-08 0.00E+00 0.00E+00 

25th 1.38E-06 1.08E-06 1.08E-06 5.61E-07 0.00E+00 0.00E+00 

50th 1.03E-05 9.51E-06 9.51E-06 5.72E-06 1.22E-08 2.19E-08 a 

75th 2.00E-04 1.88E-04 1.88E-04 9.40E-05 8.08E-07 1.08E-06 a 

95th 1.68E-02 1.68E-02 1.68E-02 7.72E-03 9.42E-05 1.07E-04 a 

Max 9.04E-01 9.04E-01 9.04E-01 7.17E-01 5.91E-01 5.91E-01 

a– Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste streams 

together in a chemical precipitation plus biological treatment system. Under Regulatory Option 5 for these 

plants, leachate is only treated with a chemical precipitation system; therefore, for some immediate receiving 

waters the metal concentrations will increase under Regulatory Option 5 compared to Regulatory Option 4. 

See the Incremental Costs and Pollutant Removals for Proposed Effluent Limitation Guidelines and Standards 

for the Steam Electric Generating Point Source Category Report for further discussion of the regulatory option 

loadings. 

F-6
 
 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Mercury Concentration in Receiving Water (mg/L) 

Figure F-6. Baseline Total Mercury Concentration in the 

Immediate Receiving Water 

Table F-7. Total Mercury Concentration (mg/L) in the Immediate Receiving
 

Water by Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.01E-09 9.69E-10 9.69E-10 6.88E-10 0.00E+00 0.00E+00 

25th 3.60E-08 2.38E-08 2.08E-08 1.71E-08 0.00E+00 0.00E+00 

50th 2.61E-07 1.87E-07 1.63E-07 1.03E-07 6.33E-10 3.26E-10 

75th 2.67E-06 1.64E-06 1.64E-06 8.71E-07 1.45E-08 1.03E-08 

95th 5.50E-05 4.95E-05 4.95E-05 3.01E-05 3.84E-07 2.63E-07 

Max 1.92E-03 1.41E-03 1.41E-03 4.02E-04 5.15E-05 5.15E-05 

F-7
 
 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Nickel Concentration in Receiving Water (mg/L) 

Figure F-7. Baseline Total Nickel Concentration in the Immediate 

Receiving Water 

Table F-8. Total Nickel Concentration (mg/L) in the Immediate Receiving 

Water by Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 2.40E-07 1.53E-07 9.76E-08 7.44E-08 0.00E+00 0.00E+00 

25th 5.80E-06 3.74E-06 3.28E-06 1.71E-06 0.00E+00 0.00E+00 

50th 6.46E-05 3.16E-05 2.85E-05 1.99E-05 6.33E-10 3.26E-10 

75th 2.11E-03 9.23E-04 8.99E-04 6.54E-04 1.45E-08 1.03E-08 

95th 9.98E-02 5.93E-02 5.93E-02 3.51E-02 3.84E-07 2.63E-07 

Max 3.32E+00 3.32E+00 3.32E+00 3.32E+00 5.15E-05 5.15E-05 

F-8
 
 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Selenium Concentration in Receiving Water (mg/L) 

Figure F-8. Baseline Total Selenium Concentration in the 

Immediate Receiving Water 

Table F-9. Total Selenium Concentration (mg/L) in the Immediate Receiving
 

Water by Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.00E-07 8.40E-08 7.68E-08 1.90E-08 0.00E+00 0.00E+00 

25th 3.54E-06 3.22E-06 1.40E-06 2.50E-07 0.00E+00 0.00E+00 

50th 3.40E-05 2.37E-05 1.05E-05 4.26E-06 8.44E-08 1.20E-07 a 

75th 7.96E-04 6.89E-04 4.12E-04 2.04E-04 4.67E-06 6.93E-06 a 

95th 1.02E-01 6.63E-02 1.38E-02 5.63E-03 1.69E-03 2.28E-03 a 

Max 3.57E+00 3.57E+00 3.57E+00 3.57E+00 3.57E+00 3.57E+00 

a– Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

F-9
 
 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Thallium Concentration in Receiving Water (mg/L) 

Figure F-9. Baseline Total Thallium Concentration in the 

Immediate Receiving Water 

Table F-10. Total Thallium Concentration (mg/L) in the Immediate Receiving
 

Water by Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.22E-07 1.22E-07 4.48E-08 3.27E-08 0.00E+00 0.00E+00 

25th 3.02E-06 2.87E-06 2.49E-06 1.08E-06 0.00E+00 0.00E+00 

50th 2.70E-05 2.68E-05 2.51E-05 1.31E-05 1.99E-08 2.66E-08 a 

75th 4.25E-04 3.96E-04 3.63E-04 1.83E-04 1.42E-06 1.25E-06 

95th 4.58E-02 4.58E-02 4.58E-02 2.38E-02 1.78E-04 1.33E-04 

Max 2.37E+00 2.37E+00 2.37E+00 2.37E+00 1.06E+00 1.06E+00 

a– Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

F-10
 
 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Zinc Concentration in Receiving Water (mg/L) 

Figure F-10. Baseline Total Zinc Concentration in the Immediate 

Receiving Water 

Table F-11. Total Zinc Concentration (mg/L) in the Immediate Receiving Water 

by Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 4.13E-07 2.94E-07 1.57E-07 1.15E-07 0.00E+00 0.00E+00 

25th 9.27E-06 6.02E-06 4.44E-06 2.33E-06 0.00E+00 0.00E+00 

50th 6.76E-05 4.14E-05 3.98E-05 2.03E-05 7.74E-08 4.30E-07 a 

75th 2.67E-03 1.83E-03 1.27E-03 5.35E-04 4.44E-06 1.77E-05 a 

95th 1.37E-01 7.05E-02 6.86E-02 3.05E-02 7.41E-04 2.41E-03 a 

Max 7.46E+00 7.46E+00 7.46E+00 7.46E+00 1.86E+00 1.86E+00 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

F-11
 
 

 

 

 

 

 

 

 

 

 

Appendix F—Additional Model Results 

a – The wildlife model applies the same total arsenic bioconcentration factors (BCFs) for both trophic level 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Arsenic Concentration in Fish Tissue (mg/kg) 

Figure F-11. Baseline Total Arsenic Concentration in Trophic 

Level 3 and Trophic Level 4 Fish Tissue in the Immediate 

Receiving Water 

3 (T3) and trophic level 4 (T4) fish (see Appendix D). Therefore, the estimated concentrations presented 

here are identical for both trophic levels. 

Table F-12. Total Arsenic Concentration (mg/kg) in Fish Tissue (T3 & T4) by 

Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 3.28E-07 3.24E-07 3.25E-07 a 1.48E-07 0.00E+00 0.00E+00 

25th 6.84E-06 6.83E-06 6.83E-06 2.75E-06 0.00E+00 0.00E+00 

50th 6.88E-05 6.88E-05 6.88E-05 2.26E-05 1.93E-07 2.36E-07 b 

75th 2.34E-03 2.28E-03 2.28E-03 1.54E-03 1.15E-05 1.12E-05 

95th 6.79E-02 6.79E-02 6.79E-02 3.51E-02 1.69E-03 1.34E-03 

Max 8.88E+00 8.88E+00 8.88E+00 8.88E+00 5.55E+00 5.55E+00 

a – Total pollutant removals for Regulatory Option 2 are greater than Regulatory Option 1; however, 

for certain pollutants the reductions estimated under Regulatory Option 2 are slightly less those 

reported under Regulatory Option 1. 

b – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

c – The wildlife model applies the same total arsenic BCFs for both T3 and T4 fish (see Appendix D). 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

F-12
 
 

 

 

 

 

 

 

 

 

Appendix F—Additional Model Results 

a – The wildlife model applies the same total cadmium BCFs for both T3 and T4 fish (see Appendix D). 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Cadmium Concentration in Fish Tissue (mg/kg) 

Figure F-12. Baseline Total Cadmium Concentration in Trophic 

Level 3 and Trophic Level 4 Fish Tissue in the Immediate 

Receiving Water 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

Table F-13. Total Cadmium Concentration (mg/kg) in Fish Tissue (T3 & T4) by 

Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 9.37E-06 5.73E-06 5.59E-06 2.74E-06 0.00E+00 0.00E+00 

25th 2.00E-04 1.22E-04 1.20E-04 6.93E-05 0.00E+00 0.00E+00 

50th 1.65E-03 1.21E-03 1.16E-03 5.82E-04 7.24E-06 1.14E-05 a 

75th 5.34E-02 2.52E-02 2.51E-02 1.54E-02 2.80E-04 4.09E-04 a 

95th 2.42E+00 1.23E+00 1.21E+00 6.53E-01 5.59E-02 5.36E-02 

Max 7.48E+01 7.48E+01 7.48E+01 4.89E+01 4.89E+01 4.89E+01 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

b – The wildlife model applies the same total cadmium BCFs for both T3 and T4 fish (see Appendix 

D). Therefore, the estimated concentrations presented here are identical for both trophic levels. 

F-13
 
 

 

 

 

 

Appendix F—Additional Model Results 

a – The wildlife model applies the same total chromium VI BCFs for both T3 and T4 fish (see Appendix 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Chromium VI Concentration in Fish Tissue (mg/kg) 

Figure F-13. Baseline Total Chromium VI Concentration in 

Trophic Level 3 and Trophic Level 4 Fish Tissue in the Immediate 

Receiving Water 

D). Therefore, the estimated concentrations presented here are identical for both trophic levels. 

Table F-14. Total Chromium VI Concentration (mg/kg) in Fish Tissue (T3 & 

T4) by Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 

25th 4.35E-09 4.35E-09 4.35E-09 3.33E-09 0.00E+00 0.00E+00 

50th 3.14E-07 3.14E-07 2.50E-07 1.23E-07 0.00E+00 0.00E+00 

75th 6.03E-06 6.03E-06 6.03E-06 2.05E-06 0.00E+00 0.00E+00 

95th 8.44E-04 8.44E-04 6.32E-04 2.51E-04 1.32E-06 6.14E-08 

Max 2.40E-01 2.40E-01 2.40E-01 1.57E-01 1.57E-01 1.57E-01 

a – The wildlife model applies the same total chromium VI BCFs for both T3 and T4 fish (see 

Appendix D). Therefore, the estimated concentrations presented here are identical for both trophic 

levels. 

F-14
 
 

 

 

 

 

 

 

Appendix F—Additional Model Results 

a – The wildlife model applies the same total lead BCFs for both T3 and T4 fish (see Appendix D). 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Lead Concentration in Fish Tissue (mg/kg) 

Figure F-14. Baseline Total Lead Concentration in Trophic Level 3 

and Trophic Level 4 Fish Tissue in the Immediate Receiving Water 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

Table F-15. Total Lead Concentration (mg/kg) in Fish Tissue (T3 & T4) by 

Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.53E-06 1.38E-06 1.38E-06 9.33E-07 0.00E+00 0.00E+00 

25th 6.37E-05 4.95E-05 4.95E-05 2.58E-05 0.00E+00 0.00E+00 

50th 4.75E-04 4.38E-04 4.38E-04 2.63E-04 5.62E-07 1.01E-06 a 

75th 9.19E-03 8.63E-03 8.63E-03 4.32E-03 3.72E-05 4.95E-05 a 

95th 7.72E-01 7.72E-01 7.72E-01 3.55E-01 4.33E-03 4.91E-03 a 

Max 4.16E+01 4.16E+01 4.16E+01 3.30E+01 2.72E+01 2.72E+01 

a– Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

b – The wildlife model applies the same total lead BCFs for both T3 and T4 fish (see Appendix D). 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

F-15
 
 

 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Methylmercury Concentration in Fish Tissue (mg/kg) 

Figure F-15. Baseline Methylmercury Concentration in Trophic 

Level 3 Fish Tissue in the Immediate Receiving Water 

Table F-16. Methylmercury Concentration (mg/kg) in Fish Tissue (T3) by
 

Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 2.43E-04 2.33E-04 2.33E-04 1.65E-04 0.00E+00 0.00E+00 

25th 8.65E-03 5.72E-03 4.98E-03 4.10E-03 0.00E+00 0.00E+00 

50th 6.26E-02 4.49E-02 3.91E-02 2.47E-02 1.52E-04 7.82E-05 

75th 6.41E-01 3.94E-01 3.94E-01 2.09E-01 3.49E-03 2.48E-03 

95th 1.32E+01 1.19E+01 1.19E+01 7.22E+00 9.22E-02 6.31E-02 

Max a 4.62E+02 3.37E+02 3.37E+02 9.65E+01 1.24E+01 1.24E+01 

a – EPA calculated methylmercury fish tissue concentrations using bioconcentration factors which do 

not fully account for the complexity of biogeochemical reactions that can occur within an aquatic 

environment and result in lower bioaccumulation rates of mercury in fish. For example, fish are 

known to bioaccumulate mercury at lower rates when exposed to surface waters with high selenium 

concentrations. In addition, bioconcentration factors do not account for a maximum limit a fish could 

accumulate before a lethal concentration is reached. To address the outliers in mercury fish tissue 

concentrations, EPA compared fish tissue concentrations to site-specific data available in the national 

fish advisory database and established calibration factors to lower the outlier values. Fish tissue 

concentrations presented in the figure and table above represent the uncalibrated values calculated by 

the wildlife model. For further details on the methodology for selecting calibration factors see ERG 

memorandum EA Model Validation and Calibration (DCN SE01986). 

F-16
 
 

 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Methylmercury Concentration in Fish Tissue (mg/kg) 

Figure F-16. Baseline Methylmercury Concentration in Trophic 

Level 4 Fish Tissue in the Immediate Receiving Water 

Table F-17. Methylmercury Concentration (mg/kg) in Fish Tissue (T4) by
 

Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.03E-03 9.88E-04 9.88E-04 7.01E-04 0.00E+00 0.00E+00 

25th 3.67E-02 2.43E-02 2.12E-02 1.74E-02 0.00E+00 0.00E+00 

50th 2.66E-01 1.91E-01 1.66E-01 1.05E-01 6.45E-04 3.32E-04 

75th 2.72E+00 1.67E+00 1.67E+00 8.89E-01 1.48E-02 1.05E-02 

95th 5.61E+01 5.05E+01 5.05E+01 3.07E+01 3.92E-01 2.68E-01 

Max a 1.96E+03 1.43E+03 1.43E+03 4.10E+02 5.25E+01 5.25E+01 

a – EPA calculated methylmercury fish tissue concentrations using bioconcentration factors which do 

not fully account for the complexity of biogeochemical reactions that can occur within an aquatic 

environment and result in lower bioaccumulation rates of mercury in fish. For example, fish are 

known to bioaccumulate mercury at lower rates when exposed to surface waters with high selenium 

concentrations. In addition, bioconcentration factors do not account for a maximum limit a fish could 

accumulate before a lethal concentration is reached. To address the outliers in mercury fish tissue 

concentrations, EPA compared fish tissue concentrations to site-specific data available in the national 

fish advisory database and established calibration factors to lower the outlier values. Fish tissue 

concentrations presented in the figure and table above represent the uncalibrated values calculated by 

the wildlife model. For further details on the methodology for selecting calibration factors see ERG 

memorandum EA Model Validation and Calibration (DCN SE01986). 

F-17
 
 

 

 

 

 

 

 

 

 

Appendix F—Additional Model Results 

a – The wildlife model applies the same total nickel BCFs for both T3 and T4 fish (see Appendix D). 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Nickel Concentration in Fish Tissue (mg/kg) 

Figure F-17. Baseline Total Nickel Concentration in Trophic Level 

3 and Trophic Level 4 Fish Tissue in the Immediate Receiving 

Water 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

Table F-18. Total Nickel Concentration (mg/kg) in Fish Tissue (T3 & T4) by 

Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.92E-07 1.23E-07 7.81E-08 5.95E-08 0.00E+00 0.00E+00 

25th 4.64E-06 2.99E-06 2.63E-06 1.37E-06 0.00E+00 0.00E+00 

50th 5.17E-05 2.53E-05 2.28E-05 1.59E-05 2.67E-08 4.81E-08 a 

75th 1.68E-03 7.39E-04 7.19E-04 5.23E-04 1.62E-06 2.99E-06 a 

95th 7.98E-02 4.74E-02 4.74E-02 2.81E-02 3.28E-04 3.34E-04 a 

Max 2.66E+00 2.66E+00 2.66E+00 2.66E+00 6.10E-01 6.10E-01 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

b – The wildlife model applies the same total nickel BCFs for both T3 and T4 fish (see Appendix D). 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

F-18
 
 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Selenium Concentration in Fish Tissue (mg/kg) 

Figure F-18. Baseline Total Selenium Concentration in Trophic 

Level 3 Fish Tissue in the Immediate Receiving Water 

Table F-19. Total Selenium Concentration (mg/kg) in Fish Tissue (T3) by
 

Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 4.92E-05 4.11E-05 3.76E-05 9.31E-06 0.00E+00 0.00E+00 

25th 1.74E-03 1.58E-03 6.84E-04 1.22E-04 0.00E+00 0.00E+00 

50th 1.67E-02 1.16E-02 5.13E-03 2.09E-03 4.13E-05 5.88E-05 a 

75th 3.90E-01 3.38E-01 2.02E-01 1.00E-01 2.29E-03 3.40E-03 a 

95th 4.98E+01 3.25E+01 6.78E+00 2.76E+00 8.28E-01 1.12E+00 a 

Max 1.75E+03 1.75E+03 1.75E+03 1.75E+03 1.75E+03 1.75E+03 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

F-19
 
 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Selenium Concentration in Fish Tissue (mg/kg) 

Figure F-19. Baseline Total Selenium Concentration in Trophic 

Level 4 Fish Tissue in the Immediate Receiving Water 

Table F-20. Total Selenium Concentration (mg/kg) in Fish Tissue (T4) by
 

Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.71E-04 1.43E-04 1.30E-04 3.23E-05 0.00E+00 0.00E+00 

25th 6.02E-03 5.48E-03 2.37E-03 4.25E-04 0.00E+00 0.00E+00 

50th 5.78E-02 4.03E-02 1.78E-02 7.24E-03 1.43E-04 2.04E-04a 

75th 1.35E+00 1.17E+00 7.00E-01 3.47E-01 7.94E-03 1.18E-02a 

95th 1.73E+02 1.13E+02 2.35E+01 9.58E+00 2.87E+00 3.87E+00a 

Max 6.06E+03 6.06E+03 6.06E+03 6.06E+03 6.06E+03 6.06E+03 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

F-20
 
 

 

 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Thallium Concentration in Fish Tissue (mg/kg) 

Figure F-20. Baseline Total Thallium Concentration in Trophic 

Level 3 Fish Tissue in the Immediate Receiving Water 

Table F-21. Total Thallium Concentration (mg/kg) in Fish Tissue (T3) by
 

Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 4.15E-06 4.15E-06 1.52E-06 1.11E-06 0.00E+00 0.00E+00 

25th 1.03E-04 9.76E-05 8.47E-05 3.67E-05 0.00E+00 0.00E+00 

50th 9.17E-04 9.13E-04 8.52E-04 4.44E-04 6.78E-07 9.05E-07 a 

75th 1.45E-02 1.35E-02 1.23E-02 6.24E-03 4.84E-05 4.24E-05 

95th 1.56E+00 1.56E+00 1.56E+00 8.08E-01 6.07E-03 4.51E-03 

Max 8.07E+01 8.07E+01 8.07E+01 8.07E+01 3.60E+01 3.60E+01 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

F-21
 
 

 

 

 

 

 

 

Appendix F—Additional Model Results 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Thallium Concentration in Fish Tissue (mg/kg) 

Figure F-21. Baseline Total Thallium Concentration in Trophic 

Level 4 Fish Tissue in the Immediate Receiving Water 

Table F-22. Total Thallium Concentration (mg/kg) in Fish Tissue (T4) by
 

Percentile
 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.59E-05 1.59E-05 5.83E-06 4.26E-06 0.00E+00 0.00E+00 

25th 3.92E-04 3.73E-04 3.24E-04 1.40E-04 0.00E+00 0.00E+00 

50th 3.51E-03 3.49E-03 3.26E-03 1.70E-03 2.59E-06 3.46E-06 a 

75th 5.53E-02 5.15E-02 4.71E-02 2.39E-02 1.85E-04 1.62E-04 

95th 5.96E+00 5.96E+00 5.96E+00 3.09E+00 2.32E-02 1.73E-02 

Max 3.09E+02 3.09E+02 3.09E+02 3.09E+02 1.38E+02 1.38E+02 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

F-22
 
 

 

 

 

 

 

 

Appendix F—Additional Model Results 

a – The wildlife model applies the same total zinc BCFs for both T3 and T4 fish (see Appendix D). 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120

Number of Plant Receiving Waters 

Total Zinc Concentration in Fish Tissue (mg/kg) 

Figure F-22. Baseline Total Zinc Concentration in Trophic Level 3 

and Trophic Level 4 Fish Tissue in the Immediate Receiving Water 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

Table F-23. Total Zinc Concentration (mg/kg) in Fish Tissue (T3 & T4) by 

Percentile 

Percentile 

Scenario 

Baseline Option 1 Option 2 Option 3 Option 4 Option 5 

5th 1.45E-04 1.03E-04 5.50E-05 4.01E-05 0.00E+00 0.00E+00 

25th 3.24E-03 2.11E-03 1.55E-03 8.16E-04 0.00E+00 0.00E+00 

50th 2.37E-02 1.45E-02 1.39E-02 7.11E-03 2.71E-05 1.51E-04 a 

75th 9.34E-01 6.39E-01 4.44E-01 1.87E-01 1.55E-03 6.18E-03 a 

95th 4.79E+01 2.47E+01 2.40E+01 1.07E+01 2.59E-01 8.43E-01 a 

Max 2.61E+03 2.61E+03 2.61E+03 2.61E+03 6.51E+02 6.51E+02 

a – Under Regulatory Option 4, some plants that discharge both leachate and FGD treat the two waste 

streams together in a chemical precipitation plus biological treatment system. Under Regulatory 

Option 5 for these plants, leachate is only treated with a chemical precipitation system; therefore, for 

some immediate receiving waters the metal concentrations will increase under Regulatory Option 5 

compared to Regulatory Option 4. See the Incremental Costs and Pollutant Removals for Proposed 

Effluent Limitation Guidelines and Standards for the Steam Electric Generating Point Source 

Category Report for further discussion of the regulatory option loadings. 

b – The wildlife model applies the same total zinc BCFs for both T3 and T4 fish (see Appendix D). 

Therefore, the estimated concentrations presented here are identical for both trophic levels. 

F-23
 
 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix G—Methodology for Non-Modeled Options 

APPENDIX G 

METHODOLOGY FOR NON-MODELED OPTIONS 

As described in Appendix C (Water Quality Model Methodology), Appendix D (Wildlife 

Model Methodology), and Appendix E (Human Health Model Methodology), the U.S. 

Environmental Protection Agency (EPA) performed modeling to estimate the water quality, 

wildlife, and human health impacts and improvements under Options 1, 2, 3, 4, and 5. EPA did 

not perform this modeling, however, for Options 3a, 3b, or 4a. Instead, EPA estimated impacts 

and improvements under these three non-modeled options by applying adjustment factors to the 

modeled impacts and improvements under Option 3. This appendix presents EPA’s methodology 

for developing and applying these adjustment factors, along with the associated limitations and 

assumptions. 14 

Development of Non-Modeled Option Adjustment Factors 

EPA developed adjustment factors by estimating the total pollutant loading removals 

from the evaluated waste streams under Options 3a, 3b, and 4a and comparing the removals to 

those under Option 3 to arrive at pollutant-specific adjustment factors. EPA estimated the 

pollutant loadings under the non-modeled options using the wastestream-specific loadings model 

output used to develop the five modeled options (Options 1, 2, 3, 4, and 5) and following the 

methodology described in the following memoranda: 

•	 Memorandum to the Rulemaking Record: Methodologies for Estimating Costs and 

Pollutant Removals for Steam Electric ELG Regulatory Options 3a and 3b (DCN 

SE03881) – This memorandum documents the methodology for calculating and 

evaluating the pollutant loadings for Options 3a and 3b. 

•	 Memorandum to the Rulemaking Record: Methodologies for Estimating Costs and 

Pollutant Removals for Steam Electric ELG Regulatory Option 4a (DCN SE03834) – 

This memorandum documents the methodology for calculating and evaluating the 

pollutant loadings for Option 4a. 

Using this pollutant loadings dataset, EPA calculated the percent difference in the 

pollutant loadings15 between options on an immediate receiving water basis. EPA then calculated 

the average across all immediate receiving waters to arrive at the pollutant-specific adjustment 

factors. This methodology assumes that the differences in environmental impacts and 

improvements between Option 3 and the non-modeled options are proportional to the differences 

in pollutant loadings. For example, an option that removes 30 percent less mercury than Option 3 

is assumed to achieve 30 percent less mercury-related environmental improvements than Option 

3. 

14 Some of the environmental impacts and improvements discussed in this report are presented in terms of pollutant 

loadings to sensitive environments and watersheds (e.g., reduced loadings of mercury to waters designated as 

impaired for mercury, Equation C-10 reduced selenium discharges to the Chesapeake Bay watershed). In these cases, 

to estimate the impacts and improvements under the three non-modeled options, EPA analyzed the pollutant 

loadings dataset for the pollutant and receiving water of concern, but did not need to apply the adjustment factor 

methodology described in this appendix. 

15 EPA developed adjustment factors for the 10 metals evaluated in the environmental assessment (EA): arsenic, 

cadmium, chromium (VI), copper, lead, mercury, nickel, selenium, thallium, and zinc. 

G-1
 
 

 

 

 

 

Appendix G—Methodology for Non-Modeled Options 

As shown in Table 6-3 of this report, the pollutant removals under Options 3a and 3b are 

less than the pollutant removals under Option 3, while the pollutant removals under Option 4a 

are greater than the pollutant removals under Option 3. This results in positive adjustment factors 

for Option 4a and negative adjustment factors for Options 3a and 3b. For example, an adjustment 

factor of 0.25 would indicate that Option 4a removed an additional 25 percent of the pollutants 

that were not removed under Option 3. An adjustment factor of -0.30 would indicate that Option 

3a removed 30 percent fewer pollutants than Option 3. 

The EA evaluates exceedances of water quality, wildlife, and human health criteria under 

baseline conditions and each of the regulatory options. Several of these criteria reflect the 

loadings of multiple pollutants. For example, the EA evaluates exceedances of the National 

Recommended Water Quality Criteria (NRWQC) for Human Health Organism Only for five 

pollutants (arsenic, nickel, selenium, thallium, and zinc). To develop an adjustment factor for this 

overall NRWQC category, EPA calculated the average of the pollutant-specific adjustment 

factors for those five pollutants. 

Table G-1 presents the pollutant-specific and criteria-specific adjustment factors used to 

estimate environmental impacts and improvements under Options 3a, 3b, and 4a. Table G-2 

identifies the pollutants whose adjustment factors were used in calculating criteria-specific 

adjustment factors. 

Table G-1. Adjustment Factors 

Pollutant-Specific Adjustment Factors a 

Pollutants Option 3a Option 3b Option 4a 

Arsenic -0.1670 -0.1295 0.2720 

Cadmium -0.2839 -0.2338 0.2823 

Chromium VI -0.0861 -0.0745 0.2920 

Copper -0.1736 -0.1361 0.2948 

Lead -0.1687 -0.1315 0.3040 

Mercury -0.2720 -0.2237 0.2859 

Nickel -0.2908 -0.2410 0.2974 

Selenium -0.3014 -0.2513 0.2410 

Thallium -0.2578 -0.2099 0.3069 

Zinc -0.2843 -0.2352 0.2865 

Criteria-Specific Adjustment Factors a 

Evaluation Criteria Option 3a Option 3b Option 4a 

Freshwater Acute NRWQC -0.2158 -0.1757 0.2894 

Freshwater Chronic NRWQC -0.2253 -0.1841 0.2840 

Human Health Water and Organism NRWQC -0.2458 -0.2005 0.2831 

Human Health Organism Only NRWQC -0.2602 -0.2134 0.2808 

Drinking Water MCL -0.2138 -0.1738 0.2849 

Fish Ingestion NEHC -0.2253 -0.1841 0.2840 

Non-Cancer Reference Dose -0.2437 -0.2007 0.2859 

Arsenic Cancer Risk -0.1670 -0.1295 0.2720 

Acronyms: National Recommended Water Quality Criteria (NRWQC); Maximum Contaminant Level (MCL); No Effect Hazard
 

Concentration (NEHC).
 

a – The adjustment factors are based on pollutant discharge loadings for a total of 297 immediate receiving waters (261 rivers and 

streams; 36 lakes, ponds, and reservoirs).
 

G-2
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix G—Methodology for Non-Modeled Options 

Table G-2. Pollutant-Specific Adjustment Factors Applicable to Evaluation Criteria 

Evaluation Criteria 

Applicable Pollutant-Specific Adjustment Factors 

As Cd CrVI Cu Pb Hg Ni Se Tl Zn 

Freshwater Acute NRWQC X X X X X X X X 

Freshwater Chronic NRWQC X X X X X X X X X 

Human Health Water and Organism 

NRWQC X X X X X X 

Human Health Organism Only 

NRWQC X X X X X 

Drinking Water MCL X X X X X X X X 

Fish Ingestion NEHC X X X X X X X X X 

Non-Cancer Reference Dose X X X X X X X X 

Arsenic Cancer Risk X 

Acronyms: Arsenic (As); Cadmium (Cd); Hexavalent Chromium (CrVI); Copper (Cu); Lead (Pb); Manganese (Mn); 

Mercury (Hg); Phosphorus (P); Selenium (Se); Zinc (Zn). 

Note: An “X” indicates that EPA compared the pollutant to a benchmark under the modeled regulatory options for 

the listed evaluation criteria. EPA calculated the average of the pollutant-specific adjustment factors (listed in Table 

G-1) applicable to each criteria to identify the criteria-specific adjustment factors (listed in Table G-1). 

EPA calculated the adjustment factors for Options 3a and 3b using Equation G-1 and the 

adjustment factors for Option 4a using Equation G-2. As described above, EPA first calculated 

the adjustment factors on an immediate receiving water basis using these equations, then 

calculated the average across all immediate receiving waters to arrive at the pollutant-specific 

adjustment factors presented in Table G-1. 

EQUATION G-1 

(L3ab − L3) AF3ab = Lbase − L3

where: 

AF3ab = Option 3a or 3b adjustment 

factor (unitless) Output from Equation G-1 

L3ab = Option 3a or 3b pollutant 

discharge load (lb/year) 

Pollutant discharge loadings using the 

methodology presented in Section 10 of 

the TDD [U.S. EPA, 2013b]. 

L3 = Option 3 pollutant discharge 

load (lb/year) 

Pollutant discharge loadings using the 

methodology presented in Section 10 of 

the TDD [U.S. EPA, 2013b]. 

Lba se = Baseline pollutant discharge 

load (lb/year) 

Pollutant discharge loadings using the 

methodology presented in Section 10 of 

the TDD [U.S. EPA, 2013b]. 

G-3
 
 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix G—Methodology for Non-Modeled Options 

EQUATION G-2 

AF4a = 

(L3 − L4a) 

L3

where: 

AF4a = Option 4a adjustment factor 

(unitless) Output from Equation G-2 

L3 = Option 3 pollutant discharge load 

(lb/year) 

Pollutant discharge loadings using 

the methodology presented in 

Section 10 of the TDD [U.S. EPA, 

2013b]. 

L4a = Option 4a pollutant discharge load 

(lb/year) 

Pollutant discharge loadings using 

the methodology presented in 

Section 10 of the TDD [U.S. EPA, 

2013b]. 

Application of Non-Modeled Option Adjustment Factors 

EPA calculated the results presented in Section 6 (Environmental Improvements under 

the Proposed Regulatory Options) for Options 3a, 3b, and 4a using the equations presented 

below. 

As discussed above, EPA calculated the adjustment factors for Options 3a, 3b, and 4a 

using Equation G-1 and Equation G-2. 

EPA used Equation G-3 and Equation G-4 to calculate the number of immediate 

receiving waters or downstream river miles that exceed an evaluation criterion. EPA calculated 

these values for Options 3a and 3b using Equation G-3 and for Option 4a using Equation G-4. 

EPA used Equation G-5 and Equation G-6 to calculate the percent reductions under an 

evaluation criterion. EPA calculated these values for Options 3a and 3b using Equation G-5 and 

for Option 4a using Equation G-6. 

EQUATION G-3 

EX3ab = EX3 × (EXbase − EX3) × AF3ab

where: 

EX3ab = 

Number of immediate receiving waters 

or downstream river miles exceeding an 

evaluation criterion under Option 3a or 

3b (unitless) 

Output from Equation G-3 

G-4
 
 

 

 

 

 

 

 

 

 

 

 

 

Appendix G—Methodology for Non-Modeled Options 

EX3 = 

Number of immediate receiving waters 

or downstream river miles exceeding an 

evaluation criterion under Option 3 

(unitless) 

Exceedance presented in 

Section 6 

EXbase = 

Number of immediate receiving waters 

or downstream river miles exceeding an 

evaluation criterion under Baseline 

(unitless) 

Exceedance presented in 

Section 6 

AF3ab = Option 3a or 3b adjustment factor 

(unitless) 

Output from Equation 

G-1(see Table G-1) 

EQUATION G-4 

EX4a = EX3 × (1 − AF4a) 

where: 

EX4a = 

Number of immediate receiving waters 

or downstream river miles exceeding an 

evaluation criterion under Option 4a 

(unitless) 

Output from Equation G-4 

EX3 = 

Number of immediate receiving waters 

or downstream river miles exceeding an 

evaluation criterion under Option 3 

(unitless) 

Exceedance presented in 

Section 6 

AF4a = Option 4a adjustment factor (unitless) Output from Equation 

G-2(see Table G-1) 

EQUATION G-5 

= ቆ

PR3 PR3ab 100 × (1 + AF3ab)ቇ × 100 

where: 

PR3ab = 

Percent reduction under Option 3a and 3b 

(unitless) Output from Equation G-5 

PR3 = Percent reduction under Option 3 

(unitless) 

Percent reduction presented 

in Section 6 

G-5
 
 

 

 

 

 

 

 

 

 

 

 

Appendix G—Methodology for Non-Modeled Options 

AF3ab = Option 3a or 3b adjustment factor 

(unitless) 

Output from Equation G-1 

(see Table G-1) 

EQUATION G-6 

= ൬

PR3 PR4a	 100൰ × AF4a൰ × 100 100 + ൬1 − PR3

where: 

PR4a = Percent reduction under Option 4a 

(unitless) Output from Equation G-6 

PR3 = Percent reduction under Option 3 

(unitless) 

Percent reduction presented 

in Section 6 

AF4a = Option 4a adjustment factor (unitless) Output from Equation G-2 

(see Table G-1) 

Non-Modeled Option Methodology Limitations and Assumptions 

The limitations and assumptions associated with using the equations described above to 

calculate the impacts to water quality, wildlife, and human health under Options 3a, 3b, and 4a 

are as follows: 

•	 This methodology assumes that changes in pollutant loadings between Option 3 and 

the non-modeled options result in proportional changes in environmental impacts and 

improvements. This simplifying assumption does not account for many of the 

complexities that are reflected in the receiving water model described in Appendix C 

(Water Quality Model Methodology), Appendix D (Wildlife Model Methodology), 

and Appendix E (Human Health Model Methodology). 

•	 As described in Memorandum to the Rulemaking Record: Methodologies for 

Estimating Costs and Pollutant Removals for Steam Electric ELG Regulatory Option 

4a (DCN SE03834), the approach for estimating pollutant loadings under the Option 

4a involves the use of adjustment factors and other assumptions. Because the analysis 

described in this appendix relies upon the estimated pollutant loadings for Option 4a, 

the limitations and assumptions associated with the loadings estimation methodology 

also apply to this analysis. 

•	 This methodology relies upon the modeled environmental improvements under 

Option 3 to estimate the improvements for the non-modeled options. Refer to 

Appendix C (Water Quality Model Methodology), Appendix D (Wildlife Model 

Methodology), and Appendix E (Human Health Model Methodology) regarding the 

limitations and assumptions associated with the receiving water model. 

G-6