United States Office of Water EPA-821-R-19-010
Environmental Protection Washington, DC 20460 November 2019
Agency
v>EPA Supplemental
Environmental Assessment
for Proposed Revisions to
the Effluent Limitations
Guidelines and Standards
for the Steam Electric Power
Generating Point Source
Category
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United States Office of Water EPA-821-R-19-010
Environmental Protection Washington, DC 20460 November 2019
Agency
£EPA
United States
Environmental Protection
Agency
Supplemental Environmental
Assessment for Proposed Revisions to
the Effluent Limitations Guidelines
and Standards for the Steam Electric
Power Generating Point Source
Category
EPA-821 -R-19-010
November 2019
U.S. Environmental Protection Agency
Office of Water (4303T)
Washington, DC 20460
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Disclaimer
This document 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.
Questions regarding this document should be directed to:
U.S. EPA Engineering and Analysis Division (4303T)
1200 Pennsylvania Avenue NW
Washington, DC 20460
(202) 566-1000
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Table of Contents
TABLE OF CONTENTS
Page
SECTION 1 INTRODUCTION 1-1
1.1 Background on Steam Electric Wastewater Discharges 1-1
1.2 Scope of the Analysis 1-2
SECTION 2 ENVIRONMENTAL AND HUMAN HEALTH CONCERNS
ASSOCIATED WITH THE EVALUATED WASTESTREAMS 2-1
2.1 Pollutants Discharged in the Evaluated Wastestreams 2-1
2.1.1 Total Dissolved Solids (TDS) Concentrations and Salinity 2-2
2.1.2 Bromide 2-4
2.1.3 Iodine 2-6
2.2 Supplemental Literature Review on Environmental Impacts of Other
Pollutants in Discharges of the Evaluated Wastestreams 2-9
SECTION 3 OVERVIEW OF METHODOLOGY FOR THE SUPPLEMENTAL
QUANTITATIVE ENVIRONMENTAL ASSESSMENT 3-1
3.1 Impact Areas Selected for Quantitative Assessment 3-1
3.2 Scope of Evaluated Plants and Immediate Receiving Waters 3-2
3.3 Pollutant Loadings for the Evaluated Wastestreams 3-3
3.4 Overview of Immediate Receiving Water (IRW) Model 3-6
3.4.1 Structure of the IRW Model 3-7
3.4.2 Pollutants Evaluated by IRW Model 3-9
3.5 Downstream Analysis 3-9
3.6 Proximity Analysis for Impaired Waters and Fish Consumption Advisory
Waters 3-10
SECTION 4 RESULTS OF THE SUPPLEMENTAL QUANTITATIVE
ENVIRONMENTAL ASSESSMENT 4-1
4.1 Estimated Pollutant Loadings for the Evaluated Wastestreams 4-1
4.2 Key Impacts Identified by IRW Model 4-4
4.2.1 Water Quality Module 4-4
4.2.2 Wildlife Module 4-9
4.2.3 Human Health Module 4-10
4.3 Impacts in Downstream Surface Waters 4-17
4.4 Discharges to Impaired Waters and Fish Consumption Advisory Waters 4-19
4.4.1 Impaired Waters 4-19
4.4.2 Fish Consumption Advisories 4-23
SECTION 5 REFERENCES 5-1
APPENDIX A ADVERSE IMPACTS FROM EXPOSURE TO METALS AND
TOXIC AND BIO ACCUMULATIVE POLLUTANTS
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Table of Contents
TABLES OF CONTENTS (Continued)
APPENDIX B
APPENDIX C
APPENDIX D
APPENDIX E
APPENDIX F
ADVERSE IMPACTS FROM EXPOSURE TO TOTAL
DISSOLVED SOLIDS
WATER QUALITY MODULE METHODOLOGY
WILDLIFE MODULE METHODOLOGY
HUMAN HEALTH MODULE METHODOLOGY
ADDITIONAL IRW MODEL RESULTS
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List of Tables
LIST OF TABLES
Page
Table 1-1. Coal-Fired Power Plant Wastestreams Evaluated in the Supplemental EA 1-3
Table 2-1. Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level
Goals (MCLGs) for Drinking Water Disinfection Byproducts (DBPs) 2-6
Table 3-1. Plants, Generating Units, and Immediate Receiving Waters Evaluated in the
Supplemental EA 3-4
Table 3-2. Plants, Generating Units, and Immediate Receiving Waters with Pollutant
Loadings under Baseline and Four Regulatory Options 3-4
Table 4-1. Estimated Industry-Level Pollutant Loadings and Estimated Change in
Loadings by Regulatory Option 4-2
Table 4-2. Estimated Annual Baseline Mass Pollutant Loadings and Estimated Change in
Loadings Under Four Regulatory Options for the Evaluated Wastestreams
(Supplemental EA Subset of Pollutants) 4-3
Table 4-3. Modeled IRWs with Exceedances of NRWQCs and MCLs under Baseline and
Four Regulatory Options 4-5
Table 4-4. Modeled IRWs with Exceedances of Any NRWQC or MCL, by Pollutant
under Baseline and Four Regulatory Options 4-6
Table 4-5. Modeled IRWs with Exceedances of NRWQCs and MCLs under Baseline and
Four Regulatory Options: Best- and Worst-Case Monthly Scenarios 4-7
Table 4-6. Modeled IRWs with Exceedances of TECs and NEHCs under Baseline and
Four Regulatory Options 4-10
Table 4-7. Modeled IRWs with Exceedances of Oral RfD (Non-Cancer Human Health
Effects) under Baseline and Four Regulatory Options 4-12
Table 4-8. Modeled IRWs with LECR Greater Than One-in-a-Million (Cancer Human
Health Effects) under Baseline and Four Regulatory Options 4-13
Table 4-9. Modeled IRWs with Exceedances of Oral RfD (Non-Cancer Human Health
Effects), by Race Category, under Baseline and Four Regulatory Options 4-14
Table 4-10. Comparison of Modeled T4 Fish Tissue Concentrations to Fish Advisory
Screening Values under Baseline and Four Regulatory Options 4-16
Table 4-11. Modeled Downstream River Miles with Exceedances of Any Pollutant
Evaluation Benchmark Value under Baseline and Four Regulatory Options 4-18
Table 4-12. IRWs Identified as Clean Water Act 303(d) Impaired Waters or Fish
Consumption Advisory Waters under Baseline and Four Regulatory Options 4-19
Table 4-13. IRWs Listed as 303(d) Impaired for Pollutants Present in the Evaluated
Wastestreams under Baseline and Four Regulatory Options 4-20
Table 4-14. IRWs with Fish Consumption Advisories for Pollutants Present in the
Evaluated Wastestreams under Baseline and Four Regulatory Options 4-24
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List of Figures
LIST OF FIGURES
Page
Figure 3-1. Locations of Immediate Receiving Waters Evaluated in the Supplemental EA 3-5
Figure 3-2. Overview of IRW Model 3-8
Figure 4-1. Worst-Case Months for Water Quality Conditions in Immediate Receiving
Waters 4-9
Figure 4-2. Immediate Receiving Waters Impaired by Mercury 4-21
Figure 4-3. Immediate Receiving Waters Impaired by Metals, Other Than Mercury 4-21
Figure 4-4. Immediate Receiving Waters Impaired by Nutrients 4-22
Figure 4-5. Immediate Receiving Waters with Fish Consumption Advisory for Mercury 4-24
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List of Abbreviations
LIST OF ABBREVIATIONS
l^g/g
Micrograms per gram
Hg/L
Micrograms per liter
|ig/m3
Micrograms per cubic meter
|iS/cm
MicroSiemens per centimeter
ADES
Advanced Emissions Solutions, Inc.
ADD
Average daily dose
AT SDR
Agency for Toxic Substances and Disease Registry
BAF
Bioaccumulation factor
BAT
Best Available Technology Economically Achievable
BCA
Benefit and Cost Analysis
BCF
Bioconcentration factor
Br-DBP
Brominated disinfection byproduct
CCME
Canadian Council of Ministers of the Environment
CCR
Coal combustion residuals
CFR
Code of Federal Regulations
CUWA
California Urban Water Agencies
DBP
Disinfection by-product
DCN
Document control number
D-FATE
Downstream Fate and Transport Equations
DNA
Deoxyribonucleic acid
DWTP
Drinking water treatment plant
EA
Environmental assessment
ED
Exposure duration
EJ
Environmental justice
ELGs
Effluent limitations guidelines and standards
EPA
U.S. Environmental Protection Agency
EPRI
Electric Power Research Institute
ERG
Eastern Research Group, Inc.
EROM
Extended Unit Runoff Method
FGD
Flue gas desulfurization
FGMC
Flue gas mercury control
FR
Federal Register
FW
Freshwater
g/kg
Grams per kilogram
GIS
Geographic information system
HAA5
Haloacetic acids
HHO
Human Health for the consumption of Organism Only
HH WO
Human Health for the consumption of Water and Organism
HQ
Hazard quotient
ICAC
Institute of Clean Air Companies
I-DBP
Iodinated disinfection byproduct
IQ
Intelligence quotient
IRW
Immediate receiving water
KDEP
Kentucky Department for Environmental Protection
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LADD
lb/yr
L/kg
LC50
LECR
LOEC
MCL
MCLG
MRL
mg/day
mg/kg
mg/kg-day
mg/m3
mg/L
mS/cm
NCDC
NEHC
NHDES
NHDPlus
NO A A
NPS
NRC
NRWQC
POTW
ppb
ppm
ppt
PSES
RfD
RIA
STORET
T3
T4
TDD
TDS
TEC
TEL
TKN
TSS
TTHM
USGS
U.S. DOJ
U.S. EPA
UV
VIP
WHO
List of Abbreviations
Lifetime average daily dose
Pounds per year
Liter per kilogram
Median lethal concentration
Lifetime excess cancer risk
Lowest observed effect concentration
Maximum contaminant level
Maximum contaminant level goal
Minimal risk level
Milligrams per day
Milligrams per kilogram
Milligrams per kilogram per day
Milligram per cubic meter
Milligrams per liter
MilliSiemens per centimeter
National Climatic Data Center
No effect hazard concentration
New Hampshire Department of Environmental Services
National Hydrography Dataset Plus
National Oceanic and Atmospheric Administration
National Park Service
National Research Council of the National Academies
National Recommended Water Quality Criteria
Publicly owned treatment works
Parts per billion
Parts per million
Parts per thousand
Pretreatment Standards for Existing Sources
Reference dose
Regulatory impact analysis
EPA's STOrage and RETrieval Data Warehouse
Trophic level 3
Trophic level 4
Technical Development Document
Total dissolved solids
Threshold effect concentration
Threshold effect level
Total Kjeldahl nitrogen
Total suspended solids
Total trihalomethanes
United States Geological Survey
United States Department of Justice
United States Environmental Protection Agency
Ultraviolet
Voluntary incentive program
World Health Organization
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Section 1—Introduction
SECTION 1
INTRODUCTION
The U.S. Environmental Protection Agency (EPA) promulgated revised effluent limitations
guidelines and standards (ELGs) for the Steam Electric Power Generating Point Source Category
(40 CFR 423) on November 3, 2015 (80 FR 67838), referred to hereinafter as the "2015 rule." In
support of the development of the 2015 rule, the EPA conducted an environmental assessment
(EA) to evaluate the environmental impact of pollutant loadings discharged by coal-fired power
plants and assess the potential environmental improvement from pollutant loading changes under
the rule. The EPA documented the EA in the September 2015 report, Environmental Assessment
for the Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating
Point Source Category (EPA 821-R-15-006) (U.S. EPA, 2015a), referred to hereinafter as the
"2015 Final EA." Following promulgation, the EPA received seven petitions for review of the
2015 rule, and the Administrator announced his decision to reconsider the 2015 rule in an April
12, 2017, letter. See the Supplemental Technical Development Document for Proposed Revisions
to the Effluent Guidelines and Standards for the Steam Electric Power Generating Point Source
Category (Supplemental TDD) (U.S. EPA, 2019a) for additional background and information on
rulemaking history. The EPA is now conducting a new rulemaking regarding the appropriate
technology bases and associated limits for the best available technology economically achievable
(BAT) effluent limitations and pretreatment standards for existing sources (PSES) applicable to
flue gas desulfurization (FGD) wastewater and bottom ash transport water discharged from coal-
fired power plants. To support the new rulemaking, the EPA conducted a Supplemental EA on
the two wastestreams being evaluated.
The Clean Water Act does not require that the EPA assess the water-related environmental
impacts, or the benefits, of its ELGs, and the Agency did not make its decision on the proposed
rule based on the expected benefits of the rule. The EPA does, however, inform itself of the
benefits of its rule, as required by Executive Order 12866. See the Benefit and Cost Analysis for
Proposed Revisions to the Effluent Limitations Guidelines and Standards for the Steam Electric
Power Generating Point Source Category (BCA Report) (U.S. EPA, 2019b). The Supplemental
EA evaluated the potential environmental impacts due to pollutant loadings under baseline
discharge practices (i.e., following full implementation of the 2015 rule) and the changes in those
impacts under varying regulatory options of this proposed rule.
1.1 Background on Steam Electric Wastewater Discharges
Based on demonstrated impacts documented in literature and modeled receiving water pollutant
concentrations, discharges of coal-fired power plant wastewater can impact the water quality in
receiving waters, impact the wildlife in the surrounding environments, and pose a human health
risk to nearby communities. There is substantial evidence that pollutants (e.g., mercury and
selenium) found in coal-fired power plant wastewater discharges propagate from the aquatic
environment to terrestrial food webs, indicating a potential for broader impacts on ecological
systems by diminishing population diversity and disrupting community dynamics in the areas
surrounding coal-fired power plants. Ecosystem recovery from exposure to pollutants in power
plant wastewater discharges can be extremely slow. Even short periods of exposure (e.g., less
than a year) can cause observable ecological impacts that last for years (Benson and Birge, 1985;
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Section 1—Introduction
Brandt et al., 2017; Canedo-Argiielles et al., 2013; CCME, 2018; Coughlan and Velte, 1989;
Evans and Frick, 2001; Evers et al., 2011; Garrett and Inman, 1984; Guthrie and Cherry, 1976;
Hallock and Hallock, 1993; Javed et al., 2016; Kimmel and Argent, 2010; Lemly, 1985, 1993,
1997, 1999, and 2018; NPS, 1997; NRC, 2006; Rowe et al., 2001 and 2002; Ruhl et al., 2012;
Sorensen, 1988; Specht et al., 1984; U.S. EPA, 2011a and 2015a; U.S. EPA Region 5, 2016;
Velasco et al., 2018; Weber-Scannell and Duffy, 2007; WHO, 1992).
Coal-fired power plants often discharge wastewater into waterbodies used for recreation and as
sources of drinking water. Numerous studies have raised concern regarding the toxicity of these
wastestreams and their impacts on downstream drinking water treatment systems (Brandt et al.,
2017; Cornwell et al., 2018; ERG, 2019a, 2019b, and 2019c; Good and VanBriesen, 2016 and
2017; Javed et al., 2016; Lemly, 2018; McTigue et al., 2014; Ruhl et al., 2012; States et al.,
2013). These discharges can also elevate halogen levels in surface water, which may contribute
to disinfection byproduct formation at downstream drinking water treatment plants.
1.2 Scope of the Analysis
The Steam Electric Power Generating Point Source Category ELGs apply to establishments
whose generation of electricity is the predominant source of revenue or principal reason for
operation, and whose generation results primarily from a process utilizing fossil-type fuels (coal,
oil, or gas), fuel derived from fossil fuel (e.g., petroleum coke, synthesis gas), or nuclear fuel in
conjunction with a thermal cycle using the steam water system as the thermodynamic medium.
In this Supplemental EA, the EPA uses the term "coal-fired power plant wastewater" to represent
all combustion-related wastewaters that contain pollutants covered by the steam electric ELGs.1
As noted earlier, the Supplemental EA evaluated two wastestreams from coal-fired power plants
whose limits would be revised under the new rulemaking (FGD wastewater and bottom ash
transport water), as described in Table 1-1.
1 The steam electric ELGs control the discharge of pollutants to surface waters and do not regulate "wastewater." To
allow for more concise discussion in this Supplemental EA, the EPA occasionally refers to "wastewater" discharges
and impacts without referencing the pollutants in the wastewater discharges.
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Section 1—Introduction
Table 1-1. Coal-Fired Power Plant Wastestreams Evaluated in the Supplemental EA
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Description
FGD wastewater
Wastewater generated from a wet FGD scrubber system. Wet FGD systems are used to
control sulfur dioxide (SO2) and mercury 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 (including refined coal), the sorbents and additives used, the materials used to
construct 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 chlorides, total dissolved solids (TDS), total suspended solids (TSS);
nutrients, halogens, metals, and other toxic and bioaccumulative pollutants, such as arsenic
and selenium (see the Supplemental TDD for further details).
In the 2015 rule, the EPA established numeric effluent limitations for mercury, arsenic,
selenium, and nitrate/nitrite as nitrogen (N) in FGD wastewater, based on treatment using
chemical precipitation followed by biological treatment.
Bottom ash
transport water
Water used to convey the bottom ash particles collected at the bottom of the boiler.
Bottom ash transport waters contain halogens, total dissolved solids (TDS), total suspended
solids (TSS), metals, and other toxic and bioaccumulative pollutants, such as arsenic and
selenium (see the Supplemental TDD for further details). The effluent from surface
impoundments typically contains low concentrations of TSS; however, arsenic, bromide,
selenium, and metals are still present in the wastewater, predominantly in dissolved form.
In the 2015 rule, the EPA established zero discharge limitations for bottom ash transport
water based on one of two technologies: (1) dry handling or (2) closed-loop systems.
The goal of the Supplemental EA was to answer the following two questions regarding pollutant
loadings from the two evaluated wastestreams:
• What are the environmental and human health concerns regarding the pollutants
being discharged with the evaluated wastestreams?
• What are the potential changes to water quality, wildlife, and human health impacts
under the regulatory options compared to baseline (i.e., the 2015 rule)?
The Supplemental EA evaluated environmental concerns and potential exposures (ecological and
human) to pollutants commonly found in wastewater discharges from coal-fired power plants.
The EPA completed both qualitative and quantitative analyses. Qualitative analyses included
reviewing additional literature documenting site impacts; assessing the pollutant loadings to
receiving waters—including those designated as impaired or with a fish consumption advisory—
under baseline and the regulatory options; and reviewing the effects of pollutant exposure on
ecological and human receptors. To quantify impacts associated with these discharges, the EPA
used a computer model2 to estimate pollutant concentrations in the immediate receiving waters,
pollutant concentrations in fish tissue, and potential exposure doses to ecological and human
receptors from fish consumption. The EPA compared the values calculated by the model to
2 See Section 3.4 of this report for an overview of the model.
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Section 1—Introduction
benchmark values to assess the extent of the environmental impacts nationwide. The EPA only
evaluated the impacts of FGD wastewater and bottom ash transport water discharges and the
incremental impacts of only these two wastestreams from coal-fired power plants.
The EPA assessed environmental impacts under baseline and four regulatory options, as shown
in Table VII-1 of the preamble to the proposed rule. The EPA also developed subcategories for
both of the evaluated wastestreams, also shown in Table VII-1. In general, each succeeding
regulatory option from Option 1 to 4 would achieve more reduction in FGD wastewater pollutant
discharges.
The EPA evaluated 112 coal-fired power plants that discharge one or both of the evaluated
wastestreams directly or indirectly to surface waters under baseline and/or the regulatory options,
and performed the quantitative modeling on a subset of 105 of these plants. The analyses
presented in this report account for publicly announced plans from the steam electric power
generating industry to retire or modify coal-fired generating units at specific power plants by
December 31, 2028. See Section 3.2 of this report for additional details on the scope of the
Supplemental EA.
The assessments described in this Supplemental EA focus on environmental impacts caused by
exposure to pollutants in the evaluated wastestreams through the surface water exposure
pathway. However, the proposed rule may have other environmental impacts unrelated to
exposure to pollutants in wastewater discharges. Examples include changes in ground water and
surface water withdrawals by coal-fired power plants; changes in the amount of dredging activity
necessary to maintain capacities in reservoirs downstream from coal-fired power plants; and
changes in air emissions due to changes in electricity use, transportation requirements, and the
profile of electricity generation. These impacts are discussed in the EPA's Benefit and Cost
Analysis for Proposed Revisions to the Effluent Limitations Guidelines and Standards for the
Steam Electric Power Generating Point Source Category (BCA Report).
The Supplemental EA does not evaluate impacts caused by migration of pollutants from surface
impoundments into ground water. The preamble to the proposed rule discusses how the EPA's
Coal Combustion Residual (CCR) Rule addresses this type of impact and how it relates to this
proposed rulemaking.
This report presents the methodology and results of the qualitative and quantitative analyses
performed for the Supplemental EA. In addition to this Supplemental EA, the proposed rule is
supported by several reports including:
• Regulatory Impact Analysis for Proposed Revisions to the Effluent Limitations
Guidelines and Standards for the Steam Electric Power Generating Point Source
Category (RIA), Document No. EPA-821-R-19-012. This report presents a profile of
the steam electric power generating industry, a summary of the costs and impacts
associated with the regulatory options, and an assessment of the proposed rule's
impact on employment and small businesses.
• Benefit and Cost Analysis for Proposed Revisions to the Effluent Limitations
Guidelines and Standards for the Steam Electric Power Generating Point Source
Category (BCA Report), Document No. EPA-821-R-19-011 (U.S. EPA, 2019b). This
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Section 1—Introduction
report summarizes the monetary benefits and societal costs that result from
implementation of the proposed rule.
• Supplemental Technical Development Document for Proposed Revisions to the
Effluent Limitations Guidelines and Standards for the Steam Electric Power
Generating Point Source Category (Supplemental TDD), Document No. EPA-821-R-
19-009 (U.S. EPA, 2019a). This report includes background on the proposed rule;
industry description; wastewater characterization and identification of pollutants of
concern; treatment technologies and pollution prevention techniques; and
documentation of EPA's engineering analyses to support the proposed rule, including
cost estimates, pollutant loadings, and a non-water-quality environmental impact
assessment.
These reports are available in the public record for the proposed rule and on the EPA's website at
https://www.epa.gov/eg/steam-electric-power-generating-effluent-guidelines-2019-proposed-
revisions.
The proposed rule is based on data generated or obtained in accordance with the EPA's Quality
System and Information Quality Guidelines.3 The EPA's quality assurance and quality control
activities for this rulemaking include the development, approval, and implementation of Quality
Assurance Project Plans for using environmental data generated or collected from all sampling
and analyses, existing databases, and literature searches, and for developing any models that used
environmental data. Unless otherwise stated within this document, the EPA evaluated the data
used and associated data analyses as described in these quality assurance documents to ensure
that they are of known and documented quality; meet the EPA's requirements for objectivity,
integrity, and utility; and are appropriate for the intended use.
3 See the following EPA websites for further details: https://www.epa.gov/aualitv/about-epas-aualitv-SYStem and
https://www.epa.gov/aualitv/epa-information-qualitv-guidelines
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
SECTION 2
ENVIRONMENTAL AND HUMAN HEALTH CONCERNS
ASSOCIATED WITH THE EVALUATED WASTESTREAMS
Discharges of flue gas desulfurization (FGD) wastewater and bottom ash transport water (the
evaluated wastestreams) from coal-fired power plants contain toxic and bioaccumulative
pollutants (e.g., selenium, mercury, arsenic, nickel), halogen compounds (containing bromide,
chloride, or iodide), nutrients, and total dissolved solids (TDS), which can cause environmental
harm through the contamination of surface waters. Certain pollutants in the discharges pose a
danger to ecological communities due to their persistence in the environment and
bioaccumulation in organisms. These factors can slow ecological recovery and can have long-
term impacts on aquatic organisms, wildlife, and human health. Numerous studies document
ecological impacts such as fish mortality, genotoxicity, and lower fish survival and reproduction
rates resulting from exposure to pollutants in coal-fired power plant discharges.4 Halogen
compounds associated with coal-fired power plant discharges also raise ecological and human
health concerns. Halogens present in source water for drinking water treatment plants (DWTPs)
can interact with disinfection processes to form halogenated disinfection byproducts (DBPs),
which can pose a risk to human health.
The EPA documented environmental and human health concerns from coal-fired power plant
discharges in the 2015 Final EA (U.S. EPA, 2015a). For this Supplemental EA, the EPA
conducted a supplemental literature review that consisted of identifying and evaluating peer-
reviewed journal articles, along with other published materials, and focused on environmental,
ecological, and human health impacts resulting from discharges of pollutants in FGD wastewater
and bottom ash transport water. This section presents a summary of relevant findings. Some of
the articles documented impacts of coal-fired power plant discharges but did not provide specific
wastestream details. When such details were documented in reviewed articles, the EPA included
details regarding applicable wastestreams. See the memorandum "Methodology and Results of a
Targeted Literature Search of Environmental Impacts from Steam Electric Power Plants" for
additional details (ERG, 2019a).
This section details environmental concerns associated with wastewater discharges from coal-
fired power plants, including the contamination of surface water, toxic effects on fish and aquatic
life, and human health concerns.
2.1 Pollutants Discharged in the Evaluated Wastestreams
The EPA evaluated the pollutants discharged in FGD wastewater and bottom ash transport water
for this Supplemental EA. Once these pollutants are released into the environment, they can
reside for a long time in the receiving waters, bioaccumulating and/or binding with sediments.
The 2015 Final EA presented the potential environmental, ecological, and human health
concerns associated with exposure to metals, toxic bioaccumulative pollutants, nutrients, and
TDS.5 This Supplemental EA focuses on the impacts of discharges of TDS (and the resulting
4 See 2015 Final EA; Brandt et al., 2017; Javed et al., 2016; Lemly, 2018.
5 The 2015 Final EA discussed chloride and bromide discharges as part of the TDS parameter.
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
salinity of the receiving water) and halogens. Additionally, Appendix A provides examples of
potential adverse impacts to humans and wildlife resulting from exposure to metals and toxic
bioaccumulative pollutants in the evaluated wastestreams and provides the minimal risk level
(MRL) for human oral exposure (or similar benchmark value) for reference. Adverse impacts
from coal-fired power plant discharges of these pollutants and nutrients are discussed further in
the 2015 Final EA.
2.1.1 Total Dissolved Solids (TPS) Concentrations and Salinity
The concentration of TDS in water is a direct indication of the water's salinity. The primary
constituents of TDS are organic salts and dissolved metals; small amounts of organic material
can also be present. Common inorganic salts found in TDS can include cations (positively
charged ions) of calcium, magnesium, potassium, and sodium, and anions (negatively charged
ions) such as carbonates, nitrates, bicarbonates, chlorides, and sulfates. TDS concentrations in
the evaluated wastestreams include dissolved metals and halogens, which can cause negative
impacts (described in Appendix A and the following sections).
TDS concentrations higher than 700 milligrams per liter (mg/L) can result in reduced growth,
decreased survival rates, and altered behavior in macroinvertebrate communities (U.S. EPA,
2018a). Appendix B presents examples of adverse impacts associated with elevated TDS
concentrations in receiving water.
Salinity represents the total concentration of dissolved salts (a subset of TDS) in the water. Salts
in inland waters consist primarily of the following cations: calcium (Ca2+), magnesium (Mg2+),
sodium (Na+), and potassium (K+); and the following anions: bicarbonate (HCO32"), carbonate
(CO32), sulfate (SO42"), and chloride (CI") (Wetzel, 1983). Salts can enter water naturally,
through erosion of soils and geologic formations over time and introduction of their dominant
ions to local freshwater systems (Olson and Hawkins, 2012; Hem, 1985; Pond, 2004; U.S. EPA,
201 Id). For example, salinity in freshwater lakes typically falls within the 100 to 500 mg/L
range and is predominantly driven by calcium carbonate (Evans and Frick, 2001).
Human activity can increase salt concentrations in surface and ground water. Direct
anthropogenic sources of salts include mining activities, use of road salt for de-icing, and
discharge of sewage and industrial wastewater (Canedo-Argiielles, 2013). Land use decisions,
such as construction activities, resource extraction, and irrigation activities, can indirectly
increase salt concentrations by increasing erosion and the transport of ions to surface waters
(Canedo-Argiielles et al., 2018). Additionally, saltwater intrusion into freshwater systems has
been well documented in coastal areas of the United States and can be caused by factors
including groundwater extraction and road construction projects and culverts (Barlow and
Reichard, 2010; Stewart et al., 2002). Once salinity has increased in freshwater systems, the
effect can be persistent. In lentic waters such as lakes and ponds, even small increases in salts
can result in long-term increases in salinity, lasting months or years (Evans and Frick, 2001).
Freshwater aquatic organisms are adapted to specific salinity ranges and can experience adverse
effects on fitness and survival when salinity increases beyond their tolerance (Canedo-Argiielles
et al., 2018). Increases in aquatic salinity can cause shifts in biotic communities, limit
biodiversity, exclude less-tolerant species, and result in acute or chronic effects at specific life
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
stages (Weber-Scannell and Duffy, 2007). TDS toxicity in the aquatic environment depends on
its ionic composition and the interaction between ions present in the TDS discharge and the
receiving water (Mount et al., 1993 and 1997).
Researchers have documented consequences of elevated salinity for aquatic organisms and
ecosystems. Velasco et al. (2018) performed a meta-analysis of studies that evaluated salinity
impacts in aquatic environments and found that 43 percent of the studies reported negative
impacts to aquatic organisms (e.g., decreased survival and growth, increased osmolyte
concentration in body fluids, and changes to metabolic rates), while 20 percent of the studies
found positive impacts, primarily on increased survival or tolerance to heat or cold stress.
Benthic invertebrates, including caddisfly, mayfly, Nais variabilis (oligochaete), and mosquito
larvae, exposed to sodium chloride (NaCl) concentrations ranging from 1,300 to 12,000 mg/L
exhibit mortality and reduced survival (Evans and Frick, 2001). Fish mortality occurs at NaCl
concentrations ranging from 5,500 to 12,000 mg/L for certain species of rainbow trout, Indian
carp fry, minnows, and goldfish. At higher concentrations (14,000 to 50,000 mg/L), other fish
species (e.g., bluegill sunfish, channel catfish, rainbow trout species, brook trout, and golden
shiners) exhibit decreased survival and recovery (Evans and Frick, 2001). Increased salinity has
been linked to adverse effects on freshwater ecosystems, including increases in invasive species,
lower rates of organic matter processing, changes in biogeochemical cycles, decreased riparian
vegetation, and altered composition of primary producers (i.e., plants, bacteria, and algae)
(Canedo-Argiielles et al., 2013).
Elevated levels of TDS in the source water can also negatively impact downstream drinking
water treatment and distribution by accelerating corrosion of transport pipes and producing
organoleptic effects (e.g., undesirable taste). The EPA has not set a primary maximum
contaminant level (MCL) for TDS but has set a secondary MCL for TDS as a nuisance parameter
at 500 mg/L. Above this level, drinking water can demonstrate hardness, deposits, color,
staining, and a salty taste (U.S. EPA, 2017 and 2018a). Individual halides, such as bromide,
chloride, and iodide, in source water can cause the formation of DBPs at downstream DWTPs,
which can impact human health (Cornwell et al., 2018; Corsi et al., 2010; ERG, 2019c; Good
and VanBriesen, 2016 and 2017; McTigue et al., 2014; Ruhl et al., 2012; States et al., 2013).
At coal-fired power plants, the average TDS concentration in untreated FGD wastewater is
33,300 mg/L. Untreated FGD wastewater has been reported to contain average concentrations of
the following ions (U.S. EPA, 2015b):
• Calcium: 3,290 mg/L (total) and 2,050 mg/L (dissolved).
• Chloride: 7,180 mg/L.
• Magnesium: 3,250 mg/L (total) and 3,370 mg/L (dissolved).
• Sodium: 2,520 mg/L (total) and 276 mg/L (dissolved).
• Sulfate: 13,300 mg/L.
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
2.1.2 Bromide
Bromine is naturally present in coal. Some coal-fired power plants also add bromine to their
combustion processes to enhance mercury emissions control or burn refined coal amended with
bromide compounds (U.S. EPA, 2019a). After combustion, bromine partitions in part to FGD
wastewater and bottom ash transport water in its anion form, known as bromide (EPRI, 2014;
Peng et al., 2013). Documented bromide levels in FGD wastewater vary widely and can exceed
175 mg/L (EPRI, 2009; Good, 2018; U.S. EPA, 2015c and 2019a). Average bromide levels of
5.1 mg/L have been documented in bottom ash transport wastewaters (U.S. EPA, 2019a). These
levels are higher than the average levels of 0.014 mg/L to 0.2 mg/L reported for freshwater
surface waters (Bowen, 1966 and 1979; Canada, 2015; McGuire et al., 2002). Field-based and
modeling studies document elevated bromide levels in surface waters downstream of steam
electric power plants and identify FGD wastewater discharges as a substantive source of bromide
loadings from the plants (Cornwell et al., 2018; Good and VanBriesen, 2016, 2017, and 2019;
McTigue et al., 2014; Ruhl et al., 2012; States et al., 2013; U.S. DOJ, 2015; U.S. EPA, 2015c).
Bromide is highly soluble and nonreactive in freshwater systems and is consequently used as a
tracer for hydrology field studies (Brantley et al., 2014; Cowie et al., 2014; Cox et al., 2003;
Flury and Papritz, 1993; Writer et al., 2011). Because of this stability, studies of bromide fate
and transport in freshwater systems focus on downstream transport and dilution of mass loadings
in surface water flow volume (Cornwell et al., 2018; Good and VanBriesen, 2016, 2017, and
2019; Harkness et al., 2015; Ruhl et al., 2012; States et al., 2013; Weaver et al., 2015; Wilson
and VanBriesen, 2013).
Bromide's toxicity in freshwater aquatic environments is low relative to substances such as
copper or cadmium cations. Reviews of freshwater aquatic organism toxicology studies cite
effect concentrations that range from 110 to 4,600 mg/L for single-celled organisms, 2.2 to
11,000 mg/L for invertebrates, and 7.8 to 24,000 mg/L for fish (EPRI, 2014; Flury and Papritz,
1993). Bromide's toxicity for human beings through oral ingestion is also low relative to other
substances. The World Health Organization (WHO) estimates that consumption of drinking
water supplies with bromide concentrations below 2.0 mg/L would meet acceptable daily intake
levels for both children and adults (WHO, 2009). As noted in Section 2.1.1, bromide also
contributes to TDS levels, salinity levels, and potential associated effects in surface waters.
While bromide's direct toxicity is relatively low, toxicity associated with its contribution to DBP
formation in drinking water treatment and distribution systems can be greater (Krasner, 2006;
Krasner et al., 2009; Regli et al., 2015; Richardson and Postigo, 2011; U.S. EPA, 2016a; Yang et
al., 2014). DBPs are a broad class of compounds that form as byproducts of drinking water
disinfection, some of which have toxic properties. Bromide in source water becomes highly
reactive in the presence of commonly used drinking water disinfectants and can form brominated
DBPs (Br-DBPs) at low source water concentrations (Bond et al., 2014; Chang et al., 2001; Heeb
et al., 2014; Landis et al., 2016; Parker et al., 2014; Richardson et al., 2007; U.S. EPA, 2016a;
Wang et al., 2017; Westerhoff et al., 2004). While multiple factors affect DBP formation6,
6 Additional factors influencing DBP formation include pH, temperature, disinfection process type and dosage level,
organic material levels and type, and treatment and distribution system residence time (Brown et al., 2011; Hong et
al., 2013; Obolensky and Singer, 2008).
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
increases and decreases in source water bromide levels are generally associated with concurrent
increases and decreases in both total DBP and bromide speciation levels in treated water
(AWWARF and U.S. EPA, 2007; Bond et al., 2014; Cornwell et al., 2018; Ged and Boyer, 2014;
Hua et al., 2006; Huang et al., 2019; Landis et al., 2016; McTigue et al., 2014; Obolensky and
Singer, 2008; Pan and Zhang, 2013; Regli et al., 2015; Sawade et al., 2016; States et al., 2013;
Yang and Shang, 2004; Zha et al., 2014).
Toxicology and epidemiology studies have documented evidence of genotoxic (including
mutagenic), cytotoxic, and carcinogenic properties of DBPs, including Br-DBPs (National
Toxicology Program, 2018; Richardson et al., 2007; U.S. EPA, 2016a). Studies have
documented evidence of a linkage between DBP exposure and bladder cancer and, to a lesser
degree, colon and rectal cancer, other cancers, and reproductive and developmental effects
(Cantor et al., 2010; Chisholm, 2008; Regli et al., 2015; Richardson et al., 2007; U.S. EPA,
2016a; Villanueva et al., 2004, 2007, and 2015). Br-DBPs generally have higher toxicity than
their chlorinated analogues (Cortes and Marco, 2018; Plewa et al., 2008; Richardson et al., 2007;
Sawade et al., 2016; U.S. EPA, 2016a; Yang et al., 2014). Due to bromide's reactivity and DBP
toxicity, elevated bromide levels in source waters have been associated with elevated health risks
from disinfected water (Hong et al., 2007; Kolb et al., 2017a; Regli et al., 2015; Sawade et al.,
2016; Wang et al., 2017; Yang et al., 2014).
Table 2-1 lists the Maximum Contaminant Level (MCL) limits that EPA has issued for select
DBPs in disinfected drinking water. These limits are intended to serve as indicator metrics for
control of total DBPs of which more than 600 individual species have been identified to date
(Richardson and Postigo, 2011; U.S. EPA, 2006 and 2016a). The DBP MCLs aim to balance the
need for adequate disinfection to control human health risks from microbial pathogens with the
human health risks from DBPs (Li and Mitch, 2018; Plewa et al., 2017; U.S. EPA, 2016a).
DWTPs must produce water of a quality that complies with MCLs. The Maximum Contaminant
Level Goal (MCLG) limits listed in Table 2-1 reflect the level below which there is no known or
expected risk to human health and are not treatment level requirements (U.S. EPA, 2009a).
DWTPs comply with DBP MCLs through a variety of techniques to adjust source water quality,
disinfection processes, and/or DBP removal as needed (McGuire et al., 2014; U.S. EPA, 2016a).
Source water quality control through direct bromide removal is infeasible in conventional
treatment systems (States et al., 2013) and instead requires specialized treatment processes (Chen
et al., 2008; CUWA, 2011; U.S. EPA, 2016a; Watson et al., 2012). In addition to cost and
operational feasibility considerations, many compliance approaches have human health risk
considerations because they modify, rather than eliminate, DBP mixtures and may not decrease
total human health risk (Bond et al., 2011; Cadwallader and VanBriesen, 2019; Francis et al.,
2010; Huang et al., 2017; Kolb et al., 2017b; Krasner, 2009; Li and Mitch, 2018; McGuire et al.,
2014; Plewa et al., 2017; States et al., 2013; U.S. EPA, 2016a; Wagner and Plewa, 2017; Watson
etal., 2014)
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
Table 2-1. Maximum Contaminant Levels (MCLs) and
Maximum Contaminant Level Goals (MCLGs) for Drinking
Water Disinfection Byproducts (DBPs)
Ki'Uiiliilcri DIJI's
MCI.
mci.c;
Bromate (plants that use ozone)
0.010 mg/L
Zero
Chlorite (plants that use chlorine dioxide)
1.0 mg/L
0.8 mg/L
Haloacetic Acids-5 (HAA5)
0.060 mg/L
Monochloroacetic acid
-
Dichloroacetic acid
Zero
Trichloroacetic acid
0.3 mg/L
Bromoacetic acid
-
Dibromoacetic acid
-
Total Trihalomethanes (TTHM)
U USD Mlu 1.
Chloroform
-
Bromodichloromethane
Zero
Dibromochloromethane
0.06 mg/L
Bromoform
Zero
Source: U.S. EPA, 2009a.
Acronyms: DBP (disinfection byproduct); mg/L (milligrams per liter).
Several studies have identified elevated bromide levels at DWTP intakes downstream of FGD
wastewater discharges from coal-fired power plants (McTigue et al., 2014; States et al., 2013;
U.S. DOJ, 2015; U.S. EPA, 2015c). Studies have also identified changes in total DBP and Br-
DBP levels at DWTPs corresponding to changes in upstream bromide discharges (Cadwallader
and VanBriesen, 2019; Cornwell et al., 2018; Marusak, 2017; McTigue et al., 2014; States et al.,
2013; U.S. DOJ, 2015; U.S. EPA, 2019c; Wang et al., 2017). The BCA Report (U.S. EPA,
2019b) describes the EPA's estimate of changes in bromides loadings from steam electric power
plants under the regulatory options, and the effects of these changes on downstream DWTPs and
associated human health risks.
In addition to their formation in DWTPs, Br-DBP formation has been documented in publicly
owned treatment works (POTWs) and other wastewater treatment facilities that disinfect
bromide-containing waters prior to discharge (Chen et al., 2009; Hladik et al., 2014; Krasner et
al., 2009; Pignata et al., 2011). A subset of steam electric power plants discharges to POTWs
(U.S. EPA, 2019a). Discharges from the treatment facilities to surface waters could contribute to
elevated Br-DBP levels in downstream surface water drinking water sources and aquatic
ecosystems. The toxicity of Br-DBPs to organisms has been documented in laboratory settings
but has not been well characterized in natural aquatic environments (Butler et al., 2005; Chen et
al., 2009; Environment Canada and Health Canada, 2010; Hanigan et al., 2017; Soltermann et
al., 2016).
2.1.3 Iodine
Iodine is naturally present in coal.7 Some coal-fired power plants also add iodine to their
combustion processes to enhance mercury emissions control or burn refined coal amended with
7 Native iodine levels in coal range from 0.15 to 12.9 ppm (Bettinelli et al., 2002; Good, 2018). One source states
that many coals used by utility plants have iodine levels greater than 3 ppm (Sjostrom et al., 2016).
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
iodide compounds (ADES, 2016; Gadgil, 2016; ICAC, 2019; Sahu, 2017; Senior et al., 2016;
Sjostrom et al., 2016; Sjostrom and Senior, 2019).8 Iodine volatilizes during combustion and
partitions to FGD wastewaters and, to a lesser extent, to bottom ash transport waters (ADES,
2016; ICAC, 2019; Meij, 1994; Peng et al., 2013; Sjostrom et al., 2016). In FGD wastewaters,
iodine occurs as iodide/triiodide anions and elemental iodine (Sjostrom et al., 2016). Limited
data on typical iodine concentrations in FGD wastewater and bottom ash transport waters are
available, though methods have been proposed for maintaining iodine concentrations in FGD
wastewater below approximately 100 mg/L to ensure normal FGD system operation and to
recover iodine for reuse (Sjostrom et al., 2016).
Typical iodine levels in freshwater surface waters are less than 0.020 mg/L, though levels
ranging from 0.00001 to 0.212 mg/L have been reported.9 In freshwater, elemental iodine
dissociates to its anionic form and/or reacts with organic material to form iodinated organic
compounds. Iodide is highly soluble and exhibits conservative fate and transport in freshwater
(Fuge and Johnson, 1986; Moran et al., 2002).
Available data on iodide's ecotoxicity in freshwater aquatic environments suggests that it is
generally lower than that of substances such as copper or cadmium cations. Estimates of median
lethal toxic concentrations (LCso) for iodide range from 860 to 8,230 mg/L for freshwater fish
and from 0.17 to 0.83 mg/L for Daphnia magna, an aquatic invertebrate (Juhnke and Ludemann,
1978; Laverock et al., 1995). Toxicity to single-celled organisms is reported to be similar to that
of bromide (Bringmann and Kiihn, 1977, 1980, and 1981). In comparison, elemental iodine
toxicity is higher for freshwater fish, with LCso concentrations from 0.53 mg/L to greater than 10
mg/L, and is similar to iodide toxicity for D. magna, with LCso concentrations from 0.16 to 1.75
mg/L (Laverock et al., 1995; LeValley, 1982). As noted in Section 2.1.1, iodide also contributes
to TDS levels, salinity levels, and the potential associated effects in surface waters.
For humans, iodine is an essential element for thyroid hormone production and metabolic
regulation. Excessive consumption can lead to hypothyroidism (diminished production of thyroid
hormones), hyperthyroidism (excessive production and/or secretion of thyroid hormones), or
thyroiditis (inflammation of the thyroid gland) (ATSDR, 2004). The MRL for acute and chronic
oral exposure to iodide is 0.01 milligrams per kilogram-day (mg/kg-day) based on endocrine
effects (ATSDR, 2019a).
While iodide's direct toxicity is relatively low, toxicity associated with iodine's contribution to
DBP formation in drinking water treatment and distribution systems can be greater. DBPs are a
broad class of compounds, some of which have toxic properties, that form as byproducts of
drinking water disinfection. Iodine in source water becomes reactive during chlorine-, chlorine
dioxide-, chloramine, or UV-based disinfection and combines with organic material in source
waters to form iodinated DBPs (I-DBPs) (Bichsel and Von Gunten, 2000; Criquet et al., 2012;
Dong et al., 2019; Hua et al., 2006; Hua and Reckhow, 2007; Krasner, 2009; Krasner et al.,
2006; Postigo and Zonja, 2019; Richardson et al., 2008; Tugulea et al., 2018; U.S. EPA, 2016a;
Weinberg et al., 2002). Both iodide and iodinated organic compounds in source waters can
8 Addition rates are reported to range from 1-30 ppm and are typically less than 10 ppm (Gadgil, 2016; ICAC, 2019;
Sjostrom et al., 2016).
9 The highest measured levels reflect influence of irrigation water return flows in arid areas.
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
contribute to I-DBP formation during drinking water disinfection (Ackerson et al., 2018; Dong et
al., 2019; Duirk et al., 2011; Pantelaki and Voutsa, 2018; Tugulea et al., 2018). Iodate, a non-
toxic iodine compound that can form in the presence of oxidants (including certain DWTP
disinfectants), can also contribute to I-DBP formation under certain conditions (Dong et al.,
2019; Postigo and Zonja, 2019; Tian et al., 2017; Xia et al., 2017; Yan et al., 2016; Zhang et al.,
2016). I-DBP levels are influenced by multiple factors and have generally been found to increase
with iodine levels in source water (Criquet et al., 2012; Dong et al., 2019; Gruchlik et al., 2015;
Postigo and Zonja, 2019; Tugulea et al., 2018; Ye et al., 2013; Zha et al., 2014).10
In vitro toxicology studies with bacteria and mammalian cells have documented evidence of
genotoxic (including mutagenic), cytotoxic, tumorigenic, and developmental toxicity properties
of I-DBPs. Individual I-DBP species have higher toxicity than their chlorinated and brominated
analogues and are among the most cytotoxic DBPs identified to date (Dong et al., 2019; Hanigan
et al., 2017; National Toxicology Program, 2018; Richardson et al., 2007 and 2008; U.S. EPA,
2016a; Wagner and Plewa, 2017; Wei et al., 2013; Yang et al., 2014). While studies have
documented evidence linking disinfected drinking water and DBP exposure to adverse human
health effects (see Section 2.1.2), additional research is needed to characterize the contribution of
I-DBPs to these effects (Cortes and Marcos, 2018; Dong et al., 2019; Postigo and Zonja, 2019;
U.S. EPA, 2016a). I-DBPs can also affect drinking water aesthetics by creating medicinal flavors
and odors that are detectable at low concentrations (Cancho et al., 2000 and 2001; Hansson et al.,
1987).
The MCLs and MCLGs listed in Table 2-1 do not include limits for I-DBPs in drinking water.
As noted in Section 2.1.2, the current limits address a subset of DBPs and are indicators for
control of total DBPs, of which more than 600 individual species have been identified to date
(Richardson and Postigo, 2011; U.S. EPA, 2006 and 2016a).
Because conventional drinking water treatment processes do not effectively remove iodide from
source waters and vary in their reduction of organic material levels (U.S. EPA, 2016a; Watson et
al., 2012), they have the potential to generate I-DBPs when their source waters contain iodine.
DWTPs are not required to monitor I-DBP levels in treated water and may not be aware of the
presence of I-DBPs in their systems (Tugulea et al., 2018). As DWTPs take steps to decrease
concentrations of regulated DBPs, their actions may or may not reduce I-DBP levels, depending
on the nature of the process change (Criquet et al., 2012; Dong et al., 2019; Gruchlik et al., 2015;
Hua and Reckhow, 2007; Krasner, 2009; Li and Mitch, 2018; McGuire et al., 2014; Tugulea et
al., 2018; U.S. EPA, 2016a).
In addition to their formation in DWTPs, I-DBP formation has been documented in POTWs and
other wastewater treatment facilities that disinfect iodine-containing waters prior to discharge
(Gong and Zhang 2015; Hladik et al., 2014 and 2016). A subset of coal-fired power plants
discharges to POTWs (U.S. EPA, 2019a). Discharges from the treatment facilities to surface
waters could contribute to elevated I-DBP levels in downstream surface waters, drinking water
sources, and aquatic ecosystems. The toxicity of I-DBPs to organisms has been documented in
10 Additional factors influencing I-DBP formation include pH, temperature, disinfection process type and dosage
level, bromide levels, ammonium levels, organic material levels and type, and treatment and distribution system
residence time.
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
laboratory settings but has not yet been characterized in natural aquatic environments (Hanigan
et al., 2017; Hladik et al., 2016).
There is limited information available on the presence of iodine in the waste streams addressed in
this proposal, therefore it was not included in this analysis.
2.2 Supplemental Literature Review on Environmental Impacts of Other
Pollutants in Discharges of the Evaluated Wastestreams
This section summarizes the new information identified in the supplemental literature review on
environmental impacts caused by exposure to pollutants in discharges of the evaluated
wastestreams other than TDS, bromine, and iodine (which are described in Section 2.1).
According to the recently published peer-reviewed studies summarized below, discharges from
coal-fired power plants have the potential to cause or contribute to ecological impacts including
lethal impacts, such as fish kills, and sublethal impacts, such as teratogenic deformities,
oxidative stress, deoxyribonucleic acid (DNA) damage, and genotoxicity (Brandt et al., 2017;
Javed et al., 2016; Lemly, 2018). Additional information on ecological impacts, human health
effects, and documented cases of water quality impacts from coal-fired power plants can be
found in Section 3.3 of the 2015 Final EA. This section discusses the findings of three additional
studies identified in the supplemental literature review.
Lemly (2018) investigated selenium pollution from the E.W. Brown Electric Generating Station
in Herrington Lake, Kentucky, where coal ash wastewater discharged from ash disposal ponds
led to elevated selenium concentrations in water, sediment, benthic macroinvertebrates, and fish
tissue. The study found selenium levels two to nine times higher than the level that is toxic to
fish reproduction and survival (i.e., toxic thresholds of 1.5 micrograms per liter (|ig/L) in water,
2 micrograms per gram (j_ig/g) in sediment, and 3 j_ig/g in macroinvertebrates) (Hamilton, 2003;
Lemly, 2002 and 2018; Peterson and Nebeker, 1992; U.S. EPA, 2016b). The study collected and
examined juvenile largemouth bass (Micropterus salmoides) and found that 12.2 percent
displayed teratogenic deformities, including spinal, craniofacial, and fin deformities. The
abnormality rate is 25 times the background abnormality rate (0.5 percent). Background
abnormalities consist of only minor fin deformities. The occurrences of morphological
abnormalities and toxic levels of selenium in fish tissue confirm that coal ash discharges into
Herrington Lake are contributing to unacceptable toxicity in fish tissue. The study findings were
consistent with a previous study, conducted by the State of Kentucky in 2016 (KDEP, 2016), in
which mature bluegill (Lepomis macrochirus) and mature largemouth bass were collected from
Herrington Lake and analyzed for toxic effects. The KDEP (2016) study reported whole-body
selenium concentrations that exceeded biological effects thresholds. Nine out of the ten sampled
fish exceeded the EPA's national ambient water quality criterion of 8.5 milligrams of selenium
per kilogram (mg/kg) of whole-body fish tissue (U.S. EPA, 2016c).
Brandt et al. (2017) examined the impacts of selenium on freshwater ecosystems associated with
effluent discharges from coal-fired power plants. Selenium discharges can lead to long-term
issues in ecosystems due to prolonged retention in the environment and cycling and propagation
in the food chain. The study evaluated selenium samples from six North Carolina lakes between
2010 and 2015. Three of the lakes received current or historical selenium discharges from coal-
fired power plants and the other three lakes did not receive selenium discharges from coal-fired
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Section 2 —Environmental and Human Health Concerns Associated with the Evaluated Wastestreams
power plants (i.e., they were reference lakes11 that corresponded to each of the impacted lakes).
Sutton Lake, which received the highest selenium loading during the study period, had the
highest level of selenium in aquatic organism tissues.12 The study found that 85 percent of fish
had muscle selenium concentrations exceeding the EPA's fish tissue-specific criterion of 11.3
mg/kg and 31 percent had ovary/egg selenium concentrations exceeding the criterion of 15.1 mg/
kg. Fish tissue samples from Mayo Lake showed that 27 percent of fish had selenium
concentrations exceeding the criterion and no ovary/egg concentrations exceeding the criterion.
Fish tissue and ovary/egg selenium concentrations were significantly13 elevated in fish from all
three lakes receiving historical or current effluent discharges from coal-fired power plants
relative to those from their corresponding reference lakes.
The literature also documented heavy metals originating from coal-fired power plant discharges
as being responsible for oxidative stress and genotoxicity in receiving water fish species. Javed
et al. (2016) collected the spotted snakehead (Channapunctatus) as a bioindicator species to
evaluate the impact of metal discharges on aquatic species. Javed et al. (2016) noted in the
study's introduction that before an increase in the power plant's capacity in the 1970s, the
receiving water (a canal in Kasimpur, India) had a diverse fish population. Following an increase
in effluent discharges, numerous species disappeared. The author did not identify any studies
that examined whether the power plant was the cause of the species loss. Their study evaluated
fish tissue samples for metal concentrations (chromium, cobalt, copper, iron, manganese, nickel,
and zinc) and fish biomarkers.14 Iron was highly bioavailable and accumulated in the liver,
kidney, muscle, and integument of the fish. Biomarkers showed oxidative stress and DNA
damage in fish tissues. The kidney was the most impacted organ, while muscle tissue was the
least impacted. DNA damage was observed at statistically significant levels in the fishes' gill
cells and liver. Evaluation of fish tissue appropriate for human consumption found that
manganese fell above the WHO benchmark of 1 mg/kg (Javed et al., 2016).
11 The reference lakes are control locations that represent "natural" selenium introduction into the environment.
12 Collected aquatic organisms included largemouth bass (Micropterus salmoides), bluegill sunfish (Lepomis
macrochirus), redear sunfish (Lepomis microlophus), and redbreast sunfish (Lepomis auritus).
13 The exception was two cases (both ovary/egg selenium concentrations comparisons) in which the count of fish
collected was insufficient to establish a statistical difference.
14 Biomarkers included lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), glutathione S
transferase (GST), reduced glutathione (GSH), and DNA damage (Javed et al., 2016).
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
SECTION 3
OVERVIEW OF METHODOLOGY FOR THE SUPPLEMENTAL
QUANTITATIVE ENVIRONMENTAL ASSESSMENT
This section provides an overview of the EPA's methodology for quantitatively evaluating the
environmental and human health effects of discharges of the evaluated wastestreams to surface
waters.
3.1 Impact Areas Selected for Quantitative Assessment
An exposure pathway is the route a pollutant takes from its source (e.g., an emission stack or
wastewater outfall) to its endpoint (e.g., a surface water), and how receptors (e.g., wildlife or
people) can come into contact with it. This Supplemental EA focused the quantitative analysis on
the surface water exposure pathway and evaluated the pollutant loadings and impacts associated
with two wastestreams: flue gas desulfurization (FGD) wastewater and bottom ash transport
water.
The EPA focused its quantitative assessment on the following wildlife and human health impacts
caused by discharges of the evaluated wastestreams to surface waters under baseline (i.e.,
following full implementation of the 2015 rule) and the potential changes in those impacts under
each of the four regulatory options:
• Wildlife Impacts:
- Potential toxic effects to aquatic life based on changes in surface water quality—
specifically, exceedances of the acute and chronic National Recommended Water
Quality Criteria (NRWQC) for freshwater aquatic life.
- Potential toxic effects on sediment biota based on changes in sediment quality
within surface waters—specifically, exceedances of threshold effect
concentrations (TECs) for sediment biota.
- Bioaccumulation of contaminants and potential toxic effects on wildlife from
consuming contaminated aquatic organisms—specifically, exceedances of no
effect hazard concentrations (NEHCs), indicating a potential risk of reduced
reproduction rates in piscivorous wildlife.
• Human Health Impacts:
- Exceedances of the human health NRWQC based on two standards: 1) standard
for the consumption of water and organisms and 2) standard for the consumption
of organisms only.
- Exceedances of drinking water maximum contaminant levels (MCLs). Although
MCLs apply to drinking water produced by public water systems and not surface
waters themselves, the EPA identified the extent to which immediate receiving
waters exceeded an MCL as an indication of the degradation of the overall water
quality following exposure to the evaluated wastestreams.
- Elevated cancer risk due to consuming fish caught from contaminated receiving
waters—specifically, instances where the calculated lifetime excess cancer risk
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
(LECR) due to inorganic arsenic is greater than one excess cancer case risk per
one million lifetimes (also expressed as 10"6).
- Elevated non-cancer health risks (e.g., reproductive or neurological impacts) due
to consuming fish caught from contaminated receiving waters—specifically,
instances where the calculated average daily dose (ADD) of a pollutant exceeds
the oral reference dose (RfD) for that pollutant.
The EPA performed this quantitative assessment using the Immediate Receiving Water (IRW)
Model, described later in this section. Appendices C, D, and E of this report and Section 5 of the
2015 Final EA (U.S. EPA, 2015a) provide additional details on the IRW Model and the water
quality, wildlife, and human health benchmark values selected for use in the evaluation of
environmental effects.
The EPA also evaluated additional wildlife and human health impacts resulting from changes in
surface water quality, including impacts on threatened and endangered species; changes in
ecosystem services; and changes in human bladder cancer risk resulting from consumption of
treated drinking water with elevated levels of brominated disinfection byproducts. The
methodology and results of these analyses are presented in the BCA Report (U.S. EPA, 2019b).
All analyses compare changes from the proposed rule to changes from the 2015 rule.
3.2 Scope of Evaluated Plants and Immediate Receiving Waters
The EPA estimates that 550 coal-fired generating units operated at 284 power plants are subject
to this proposed rule. This does not include generating units and plants that are expected to retire
or convert to non-coal fuels by December 31, 2028. The EPA limited the scope of the
Supplemental EA to the 112 coal-fired power plants that will discharge one or both of the
evaluated wastestreams directly or indirectly to surface waters under baseline and/or the
regulatory options.15 The Supplemental TDD (U.S. EPA, 2019a) describes how the EPA updated
the industry profile to reflect changes since the 2015 rule, including an assessment of impacts of
other regulations affecting steam electric power plants, such as the Coal Combustion Residual
(CCR) Rule.
The IRW Model, which excludes discharges to the Great Lakes and estuaries, encompasses 105
coal-fired power plants that discharge to 106 immediate receiving waters.16 The IRW Model
excludes Great Lake and estuarine immediate receiving waters because the specific
hydrodynamics and scale of the analysis required to appropriately model and quantify pollutant
concentrations in these types of waterbodies are more complex than can be represented in the
IRW Model.
Table 3-1 presents the number of coal-fired power plants, generating units, and immediate
receiving waters evaluated in this Supplemental EA. Figure 3-1 shows the locations of the
immediate receiving waters evaluated in this Supplemental EA and indicates those that are
included in the IRW modeling. See the memorandum "Receiving Waters Characteristics
15 Of the 112 plants in the Supplemental EA, 108 plants discharge directly to surface water and four plants discharge
indirectly to a publicly owned treatment works (POTW).
16 Two of the 105 plants discharge to more than one immediate receiving water, while one modeled immediate
receiving water receives discharges from multiple plants.
3-2
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
Analysis and Supporting Documentation for the 2019 Steam Electric Supplemental
Environmental Assessment" (ERG, 2019d) for the list of immediate receiving waters and for
details regarding the EPA's methodology for identifying the immediate receiving waters.
The number of evaluated coal-fired power plants and generating units, and the number of the
associated immediate receiving waters, vary across baseline and the four regulatory options. This
is due to differences in the stringency of controls, applicability of these controls based on
subcategorization, and estimates of the control technologies that plants would implement to meet
requirements (see the preamble for details). Table 3-2 presents the number of plants, generating
units, and immediate receiving waters with nonzero pollutant loadings under baseline and each
regulatory option.
3.3 Pollutant Loadings for the Evaluated Wastestreams
To support the quantitative evaluation of environmental impacts via the surface water exposure
pathway, the EPA calculated plant-specific baseline and post-compliance pollutant loadings (in
pounds per year) for FGD wastewater and bottom ash transport water being discharged to surface
water or through publicly owned treatment works (POTWs) to surface water. The EPA estimated
baseline pollutant loadings for these two wastestreams based on the requirements established in
the 2015 rule (i.e., baseline assumes full compliance with the 2015 rule), whereas the post-
compliance loadings represent full implementation of the regulatory options across all steam
electric power plants subject to the requirements of the proposed rule. The Supplemental TDD
describes how the EPA calculated estimates of the baseline and post-compliance pollutant
loadings for each evaluated wastestream.
Four plants reported transferring wastewater to a POTW rather than discharging directly to
surface water. For these plants, the EPA adjusted the baseline and post-compliance loadings to
account for pollutant removals expected during treatment at the POTW for each analyte.
Section 4.1 of this report presents the industry-wide annual baseline pollutant loadings for FGD
wastewater and bottom ash transport water, and the post-compliance pollutant changes (relative
to baseline) for each of the four regulatory options. The plant-specific annual loadings were used
throughout the analyses described in the remainder of this section. The Supplemental EA did not
evaluate the impacts of any discharges other than the two evaluated wastestreams; therefore, the
pollutant loadings and subsequent quantitative analyses do not represent a complete assessment
of environmental impacts from coal-fired power plants.
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
Table 3-1. Plants, Generating Units, and Immediate Receiving Waters Evaluated in the
Supplemental EA
Calegon
Number r.\alualed in Pollutant
Loadings Analysis. Downstream
Analysis, and Proximity Analysis
Suhsel Also l'.\alnaled
in IRW Model
Coal-Fired Power Plants
112
105
Coal-Fired Generating Units
254
239
Immediate Receiving Waters
River/Stream
88
88
Lake/Pond/Reservoir
18
18
Great Lakes
5
--
Estuary/Bay/Other
1
--
Total Immediate Receiving Waters
112
106
Source: ERG, 2019d and 2019e.
Table 3-2. Plants, Generating Units, and Immediate Receiving Waters with Pollutant
Loadings under Baseline and Four Regulatory Options
Calcgon
Baseline
Option 1
Option 2
Oplion 3
Oplion 4
Anj Scenario
Pollutant Loadings, Downstream, and Proximity Analyses11
Coal-Fired Power Plants
69
111
97
95
70
112
Coal-Fired Generating Units
164
250
219
220
159
254
Immediate Receiving Waters
69
111
96
94
69
112
Subset Also Evaluated in 1R WModel a'b
Coal-Fired Power Plants
66
104
90
88
65
105
Coal-Fired Generating Units
156
235
204
205
148
239
Immediate Receiving Waters
66
105
90
88
64
106
Source: ERG, 2019e.
a - The IRW Model excludes discharges to the Great Lakes and estuaries because the specific hydrodynamics
and scale of the analysis required to appropriately model and quantify pollutant concentrations in these types of
waterbodies are more complex than can be represented in the IRW Model.
b - The EPA updated the pollutant loadings data set after the completion of the quantitative analyses in this
Supplemental EA. The final industry loadings calculated using these revised data sets are presented in the
Supplemental TDD and Section 4.1 of this report. However, the EPA did not rerun the proximity analyses and
IRW Model to reflect the updated loadings data sets. See the memorandum "Pollutant Loadings Analysis and
Supporting Documentation for the 2019 Steam Electric Environmental Assessment" (ERG, 2019e) for more
information.
3-4
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
112 Immediate Receiving Waters in Pollutant
Loadings, Downstream, and Proximity Analyses
Subset: 106 Rivers and Lakes Also Evaluated
® with TRW Model
Figure 3-1. Locations of Immediate Receiving Waters Evaluated in the Supplemental EA
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
In addition to calculating estimated plant-specific baseline and post-compliance pollutant
loadings, the EPA also calculated pollutant loadings to represent current industry practices
conditions for FGD wastewater and bottom ash transport water. These loadings represent the
continued use of the existing technologies at each plant, and do not assume compliance with the
discharge limits promulgated in the 2015 rule. The memorandum "Pollutant Loadings Associated
with Current Discharges of FGD Wastewater and Bottom Ash Transport Water" (ERG, 2019f)
describes the EPA's methodology for calculating the current industry practices loadings for each
evaluated wastestream. The EPA used these estimated loadings to assess the potential for
continuing impacts that could occur due to factors including delayed compliance deadlines for
selected regulatory options; discharges from generating units or plants that are subcategorized
out of a regulatory option; and discharges from plants that elect to participate in the Voluntary
Incentives Program (VIP).17
The memorandum "Pollutant Loadings Analysis and Supporting Documentation for the 2019
Steam Electric Supplemental Environmental Assessment" provides additional documentation of
the Supplemental EA loadings analyses (ERG, 2019e).
3.4 Overview of Immediate Receiving Water (IRW) Model
The EPA used the IRW Model to complete the quantitative assessment of potential wildlife and
human health impacts described in Section 3.1. The EPA used the same IRW Model described in
the 2015 Final EA and incorporated updates to selected parameters and benchmark values, as
documented in Appendices C, D, and E.
The IRW Model evaluates impacts within the immediate surface water18 where discharges occur.
Section 4.2 presents the results of the IRW Model analyses based on baseline and post-
compliance pollutant loadings for the two evaluated wastestreams.
17 As described in the preamble for the proposed rule, the EPA is proposing a VIP as part of each regulatory option
except Option 4. The VIP establishes more stringent effluent limitations, based on membrane filtration, for FGD
wastewater in exchange for additional time to comply with those limitations because the membrane technology is
not currently available nationwide and therefore is not the BAT for this proposed rule. Plants electing to participate
in the VIP would be granted additional time (until December 31, 2028) to meet these more stringent limitations.
This time extension would allow the technology to become available on a nationwide basis and allow plants more
time to conduct pilot testing, demonstrations, and further analyses associated with implementing a new technology.
18 The length of the immediate receiving water, as defined in the National Hydrography Dataset Plus (NHDPlus)
Version 2, generally ranges from approximately 1 to 5 miles; the longest immediate receiving water is 9.1 miles.
The upstream and downstream boundaries are defined in NHDPlus Version 2, and each coal-fired power plant
outfall is located somewhere along the associated immediate receiving water (i.e., the outfalls are not specifically
indexed to the upstream end, midpoint, or downstream end). See the memorandum "Receiving Waters
Characteristics Analysis and Supporting Documentation for the 2019 Steam Electric Supplemental Environmental
Assessment" (ERG, 2019g) for details on the immediate discharge zone and length of stream reach represented at
each discharge location.
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
3.4.1 Structure of the IRW Model
The IRW Model has three interrelated modules: a Water Quality Module, a Wildlife Module, and
a Human Health Module, which are described in further detail below. Figure 3-2 provides an
overview of the IRW Model inputs and the connections among the three modules to support the
EPA's modeling framework. Appendices C, D, and E describe the IRW Model equations, input
data, and environmental parameters in detail. The appendices also describe the limitations and
assumptions for each module. Section 5.1 of the 2015 Final EA provides additional information
on the IRW Model, including a detailed discussion of the equilibrium-partition modeling
methodology used in the Water Quality Module.
• Water Quality Module. This module uses plant-specific input data (annual average
pollutant loadings and cooling water flow rates) and surface water-specific
characteristic data (e.g., annual average flow rate, lake volume) to calculate annual
average total and dissolved pollutant concentrations in the water column and
sediment. The module compares these concentrations to selected water quality
benchmark values (NRWQCs and MCLs) as an indicator of potential impacts on
aquatic life and human health. The EPA supplemented these annual average outputs
by modeling the water column pollutant concentrations during best-case months (low
loadings and high flow rates, resulting in greater dilution) and worst-case months
(high loadings and low flow rates, resulting in less dilution) and comparing the results
to the NRWQCs and MCLs.19
• Wildlife Module. This module uses the annual average water column pollutant
concentrations from the Water Quality Module to calculate the bioaccumulation of
pollutants in fish tissue, providing results for both trophic level 3 (T3) and trophic
level 4 (T4) fish.20 The module compares these concentrations, and the sediment
concentrations calculated by the Water Quality Module, to benchmark values that
represent potential impacts on exposed sediment biota (TECs)21 and piscivorous
wildlife (NEHCs). The EPA selected minks and eagles as representative piscivorous
wildlife that consume T3 and T4 fish, respectively.
• Human Health Module. This module uses the fish tissue concentrations from the
Wildlife Module to calculate non-cancer and cancer risks to human populations from
19 Data regarding actual monthly loadings were not available for this analysis. Therefore, the EPA estimated
monthly loadings using monthly net electricity generation data at the coal-fired generating unit level as an indicator
of monthly discharges of the evaluated wastestreams. Using monthly flow rate data for each immediate receiving
water from NHDPlus Version 2, the EPA then identified the months that would produce the lowest (best-case) and
highest (worst-case) ratios of pollutant loadings to flow rates for each immediate receiving water and performed
water quality modeling for those selected months. See the memorandum "Monthly Water Quality Modeling
Analysis and Supporting Documentation for the 2019 Steam Electric Supplemental Environmental Assessment"
(ERG, 2019j) for further details.
20 T3 fish (e.g., carp, smelt, perch, catfish, sucker, bullhead, sauger) are those that primarily consume invertebrates
and plankton, while T4 fish (e.g., salmon, trout, walleye, bass) are those that primarily consume other fish.
21 In the case of the TEC for selenium, exceedances of the TEC represent potential impacts on higher trophic levels
due to consumption of sediment biota with elevated levels of selenium.
3-7
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
consuming fish that are caught from contaminated receiving waters. The EPA
performed this analysis using two sets of fish consumption rates:22
A "standard cohort" data set with consumption rates for recreational fishers and
subsistence fishers (and their families), with separate age categories for adult and
child fishers. Subsistence fishers are individuals who rely on self-caught fish for a
larger share of their food intake as compared to recreational fishers.
A data set with consumption rates for recreational and subsistence fishers in
different race categories (Non-Hispanic White; Non-Hispanic Black; Mexican-
American; Other Hispanic; and Other, including Multiple Races). The EPA used
this data set in an Environmental Justice analysis to evaluate whether the post-
compliance change in human health impacts (relative to baseline) will
disproportionately impact minority groups.
Risk to
Sediment
Biota
Comparison to
Fish Advisory
Screening Values
Pollutant
Concentration in
Fish Tissue
Pollutant
Concentration in
Sediment
Pollutant
Concentration in
Surface Water
Human
Health
Module
Water
Quality
Module
Wildlife
Module
Receiving Water
Characteristics
Pollutant
Loadings in
Evaluated
Wastestreams
Cooling Water
Flow Rate (if
applicable)
Risk to
Human
Health
Risk to
Wildlife
Risk to
Human
Health
Risk to
Aquatic
Life and
Human
Health
Figure 3-2. Overview of IRW Model
22 See the memorandum "Fish Consumption Rates Used in the EA Human Health Module" (ERG, 2015) for details
regarding the selection of fish consumption rates for these analyses.
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
The EPA also assessed the potential for discharges of the evaluated wastestreams to cause or
contribute to fish advisories, thereby posing a human health risk. The EPA compared the T4 fish
tissue concentrations from the Wildlife Module to fish consumption advisory screening values.
Screening values are defined as concentrations of target analytes in fish or shellfish tissue that
are of potential public health concern; they are used as threshold values to which levels of
contamination in similar tissue collected from the ambient environment can be compared.
Exceedance of these screening values indicates that more intensive site-specific monitoring
and/or evaluation of human health risks should be conducted (U.S. EPA, 2000a, Table 5-3).23
3.4.2 Pollutants Evaluated by IRW Model
In the 2015 Final EA, the EPA focused the IRW Model quantitative analyses on 10 toxic
pollutants, all of which can bioaccumulate in fish and impact wildlife and human receptors via
fish consumption. These pollutants were arsenic, cadmium, hexavalent chromium (chromium
VI), copper, lead, mercury, nickel, selenium, thallium, and zinc. Sections 4.1.2 and 5.1.1 of the
2015 Final EA provide additional discussion on the selection of these pollutants for evaluation
using the IRW Model.
For the Supplemental EA, the EPA evaluated the same ten pollutants with the exception of
chromium VI (the analytical data sets for the evaluated wastestreams do not include
concentration data for chromium VI). The Supplemental TDD describes the EPA's methodology
for estimating baseline and post-compliance pollutant loadings for each evaluated wastestream.
As was the case with the 2015 Final EA, the Supplemental EA did not use water quality
modeling to assess the impacts associated with discharges of total dissolved solids (TDS),
bromides, chlorides, or nutrients (total nitrogen and total phosphorus). These pollutants were
excluded from the IRW Model analyses primarily because of the limited availability of national-
level numeric water quality, wildlife, and human health benchmark values for comparison with
the model outputs. The EPA did include some of these pollutants in the surface water quality
modeling of immediate and downstream waters, which was performed for the economic benefits
analysis (see the BCA Report).
3.5 Downstream Analysis
As part of the economic benefits analysis, the EPA used a separate pollutant fate and transport
model (D-FATE) to calculate the concentrations of pollutants in surface waters downstream from
the immediate receiving water for each plant that discharges FGD wastewater or bottom ash
transport water. See the BCA Report for a detailed discussion of the D-FATE model and the
analysis, which uses annual average pollutant loadings and surface water flow rates.
For this Supplemental EA, the EPA used these downstream concentrations from D-FATE as
inputs for an analysis that identified which downstream reaches would have at least one
exceedance of a water quality, wildlife, or human health benchmark value under baseline or post-
compliance loadings. The EPA used this approach to estimate the extent (in river miles) of
23 See the memorandum "IRW Model: Water Quality, Wildlife, and Human Health Analyses and Supporting
Documentation for the 2019 Steam Electric Supplemental Environmental Assessment" (ERG, 2019k) for
documentation of the fish advisory screening level analysis.
3-9
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Section 3—Overview of Methodology for the Supplemental Quantitative Environmental Assessment
impacts in downstream surface waters under baseline and the changes in these impacts under the
four regulatory options. Results are presented in Section 4.3 of this report. See the memorandum
"Downstream Modeling Analysis and Supporting Documentation for the 2019 Steam Electric
Supplemental Environmental Assessment" (ERG, 2019g) for details regarding the methodology
for this analysis.
3.6 Proximity Analysis for Impaired Waters and Fish Consumption Advisory
Waters
As was the case with the 2015 Final EA, the EPA performed a proximity analysis to identify:
• Immediate receiving waters that states, territories, and authorized tribes have
identified, pursuant to Section 303(d) of the Clean Water Act, as impaired
waterbodies that can no longer meet their designated uses (e.g., drinking, recreation,
and aquatic habitat) due to pollutant concentrations that exceed water quality
standards. These impaired waterbodies are also known as "303(d)-listed
waterbodies."
• Immediate receiving waters for which states, territories, and authorized tribes have
issued fish consumption advisories, which indicates that pollutant concentrations in
the tissues of fish inhabiting those waters are considered unsafe for human
consumption at any or some consumption levels.
Section 4.4 of this report presents the results of the proximity analysis. See the memorandum
"Proximity Analyses and Supporting Documentation for the 2019 Steam Electric Supplemental
Environmental Assessment" (ERG, 2019h) for a description of the proximity analysis
methodology.
The EPA also performed further spatial analyses to identify public drinking water supply intakes
downstream from discharges of FGD wastewater and/or bottom ash transport water. See the
BCA Report regarding the methodology and results of that analysis.
3-10
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
SECTION 4
RESULTS OF THE SUPPLEMENTAL
QUANTITATIVE ENVIRONMENTAL ASSESSMENT
This section presents the estimated pollutant loadings in flue gas desulfurization (FGD)
wastewater and bottom ash transport water discharges—the evaluated wastestreams—under
baseline, the estimated pollutant loading changes associated with each of four regulatory option
scenarios, and the results of the quantitative analyses described in Section 3, which include the
following:
• Use of the EPA's Immediate Receiving Water (IRW) Model to:
- Estimate the annual average pollutant concentrations in immediate receiving
waters due to discharges of the evaluated wastestreams under baseline; estimate
the bioaccumulation of pollutants in fish tissue within those waters; and estimate
the daily and lifetime pollutant exposure doses among humans who consume
those fish.
Compare those estimated concentrations and estimated exposure doses to various
benchmark values as indicators of potential water quality, wildlife, and human
health impacts (including Environmental Justice (EJ) concerns associated with
differential fish consumption rates).
- Evaluate the estimated changes in those impacts under the regulatory option
scenarios.
- Perform a supplemental "best-case" and "worst-case" monthly water quality
analysis.
• Use of pollutant fate and transport model (D-FATE) outputs to estimate potential
water quality, wildlife, and human health impacts in downstream surface waters
under baseline and evaluate the estimated changes in those impacts under the
regulatory option scenarios.
• A proximity analysis to identify immediate receiving waters that are designated as
Clean Water Act 303(d)-listed impaired waterbodies or have been issued fish
consumption advisories.
The BCA Report (U.S. EPA, 2019b) discusses the EPA's evaluation of other impacts that were
not quantified in this Supplemental EA.
4.1 Estimated Pollutant Loadings for the Evaluated Wastestreams
As discussed in the preamble for the proposed rule, the EPA evaluated four regulatory options
for the proposed revisions to the 2015 rule. The controls of these four options differ in stringency
and in their applicability to coal-fired power plants and generating units, based on each entity's
wastestream, generation capacity, net power generation, and wet FGD scrubber flow. The EPA
estimated the pollutant loadings for baseline (2015 rule conditions) and each regulatory option,
as well as changes in pollutant loadings associated with coal-fired power plants to achieve
4-1
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
compliance for each of the main regulatory options. This section discusses estimated annual
pollutant loadings in the discharges of the evaluated wastestreams from coal-fired power plants
under baseline and each regulatory option evaluated for the proposed revisions to the 2015 rule.
Under baseline, the EPA estimates that the coal-fired power plant industry annually discharges
more than 1,670,000,000 pounds of pollutants in the evaluated wastestreams to surface waters,
either directly or via publicly owned treatment works (POTWs). Under the proposed regulatory
option (Option 2), the EPA estimates that, once all plants in scope have implemented the
provisions of Option 2, this figure will decrease by 104,000,000 pounds (6.2 percent) relative to
the 2015 rule baseline. Table 4-1 presents the estimated total industry pollutant loadings, in
pounds per year, for baseline and estimated pollutant loadings changes for each regulatory
option. The EPA estimated the changes in pollutant loadings by subtracting the baseline loadings
from the post-compliance loadings. The memorandum "Pollutant Loadings Analysis and
Supporting Documentation for the 2019 Steam Electric Supplemental Environmental
Assessment" (ERG, 2019e) discusses the EPA's methodology for estimating total industry
pollutant loadings for baseline and each regulatory option.
Table 4-1. Estimated Industry-Level Pollutant Loadings and Estimated Change in
Loadings by Regulatory Option
Regulatory Option
Estimated Total Industry Pollutant
Loading
(Ib/vcar)
Estimated Change in Total Industry
Pollutant Loadings
(lb/vear)"
Baseline
1,670,000,000
--
1
1,680,000,000
13,400,000
2
1,560,000,000
-104,000,000
3
1,390,000,000
-276,000,000
4
342,000,000
-1,320,000,000
Source: ERG, 2019e.
Note: Pollutant loadings values are rounded to three significant figures.
a - Negative values represent an estimated decrease in loadings to surface waters compared to baseline. Positive
values represent an estimated increase in loadings to surface waters compared to baseline.
The pollutants with the greatest estimated reductions in annual mass loadings under Option 2 are
total dissolved solids (TDS) (105,000,000 lb/yr decrease relative to baseline), chloride
(35,200,000 lb/yr decrease), magnesium (23,400,000 lb/yr decrease), bromide (13,400,000 lb/yr
decrease), calcium (4,800,000 lb/yr decrease), and boron (1,450,000 lb/yr decrease). However,
loadings for 27 out of 37 pollutants for which the EPA calculated loadings, including the
bioaccumulative pollutants and metals (except thallium) modeled in the IRW Model, will have
slightly higher loadings under Option 2 relative to baseline.24
24 Under Option 2, the EPA estimates that some plants will decrease FGD wastewater pollutant loadings by
recycling FGD wastewater (reducing total flow of FGD wastewater discharged), installing the Option 2 technology
basis, or by participating in the VIP (installing membrane filtration). Other plants are estimated to have increases in
total pollutant loadings, based on new proposed subcategories and the proposed purge option for bottom ash
transport water.
4-2
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
This Supplemental EA and the 2015 Final EA (U.S. EPA, 2015a) focus on a subset of the
pollutants for which the EPA calculated loadings. Table 4-2 presents estimated pollutant
loadings under baseline and pollutant loadings changes for each of the regulatory options for this
subset of pollutants. The memorandum "Pollutant Loadings Analysis and Supporting
Documentation for the 2019 Steam Electric Supplemental Environmental Assessment" (ERG,
2019e) discusses the EPA's methodology for estimating pollutant loadings for each immediate
receiving water and presents pollutant loadings under baseline and net change associated with
each of the regulatory options for all 37 pollutants for which EPA calculated loadings.
Table 4-2. Estimated Annual Baseline Mass Pollutant Loadings and Estimated Change in
Loadings Under Four Regulatory Options for the Evaluated Wastestreams (Supplemental
EA Subset of Pollutants)
Pollutant
llsliiiiiilod
liasclinc PcilIn I;int
Loadings tlh/\r)
r.slimali-ri Change in Pollutant Loadings Kclali\c to liasclino
(ll>/\ r)
Option 1
Option 2
Option 3
Option 4
Aluminum
9,060
8,780
58,000
7,340
2,200
Arsenic
407
95.7
599
25.7
-225
Boron
15,500,000
54,600
-1,450,000
-2,650,000
-12,400,000
Bromide
32,200,000
52,500
-13,400,000
-15,000,000
-29,200,000
Cadmium
302
7.41
15.8
-43.1
-223
Chloride
492,000,000
3,300,000
-35,200,000
-82,200,000
-392,000,000
Chromium
447
52.2
299
-25.1
-302
Copper
264
40.6
242
-4.78
-167
Iron
8,290
6,950
46,400
5,620
839
Lead
240
107
693
66.3
-79.2
Magnesium
233,000,000
573,000
-23,400,000
-40,000,000
-187,000,000
Manganese
870,000
1,570
-90,500
-149,000
-688,000
Mercury
4.50
6.55
8.30
1.63
-0.543
Nickel
554
355
1,220
142
-130
Nitrogen, Totalb
530,000
5,970,000
1,900,000
1,220,000
897,000
Phosphorus, Total
22,200
2,280
12,900
-1,560
-15,400
Selenium
547
57,900
18,400
12,500
12,200
TDS
1,660,000,000
13,200,000
-105,000,000
-276,000,000
-1,320,000,000
Thallium
675
11.7
-0.561
-106
-529
Vanadium
880
104
607
-47.5
-596
Zinc
1,560
347
2,180
108
-749
Total0
775,000,000
10,000,000
-71,600,000
-139,000,000
-620,000,000
Source: ERG, 2019e.
Acronyms: lb/yr (pounds per year); TDS (total dissolved solids).
Note: Pollutant loadings values are rounded to three significant figures.
a - Negative values represent an estimated decrease in loadings to surface waters compared to baseline. Positive
values represent an estimated increase in loadings to surface waters compared to baseline,
b - Total nitrogen loadings are the sum of ammonia and total Kjeldahl nitrogen (TKN) for FGD wastewater and
the sum of nitrate-nitrite (as N) and TKN for bottom ash transport water.
c - Represents the summed loadings for the subset of pollutants focused on in the Supplemental EA, excluding
TDS. Pollutant loadings exclude TDS to avoid double-counting mass.
4-3
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-2 presents estimated changes in pollutant loadings that would be achieved after industry-
wide implementation of the control technologies needed to comply with any applicable effluent
limitations at each plant. Implementation timing for each plant varies by regulatory option,
wastestream, subcategorization, and the plant's permit renewal schedule. Plants would
implement bottom ash transport water control technologies no later than December 31, 2023.
Plants would implement FGD control technologies by December 31, 2023 under Option 1; by
December 31, 2025 under Options 2 and 3; and by December 31, 2028 under Option 4. Under
Options 1, 2, and 3, plants participating in the Voluntary Incentives Program (VIP) may
implement FGD wastewater controls by December 31, 2028.25 See the preamble for further
discussion of the regulatory options and associated compliance deadlines.
Due to the differing compliance timelines for individual wastestreams and plants, the net change
in pollutant loadings and corresponding environmental changes will be staggered over time as
the plants implement control technologies. The Supplemental EA estimates post-compliance
environmental changes associated with each regulatory option using steady-state annual average
pollutant loadings reflecting full implementation of the effluent limitations. Therefore, the results
of the Supplemental EA may underestimate short-term environmental impacts for the period
prior to full implementation of the regulatory options during which plants transition from current
discharges to discharges associated with full implementation.
4.2 Key Impacts Identified by IRW Model
The IRW Model includes modules assessing potential changes in impacts on water quality,
wildlife, and human health in waters receiving discharges of the evaluated wastestreams from
coal-fired power plants.26 See Section 3 of this document and Appendices C, D, and E for
detailed discussions of the IRW Model's structure.
The following sections present the results from each module. The results identify modeled
exceedances of water quality, wildlife, and human health benchmark values under baseline and
the net changes in those exceedances under each regulatory option.27 Appendix F includes
additional IRW Model outputs.
4.2.1 Water Quality Module
The IRW Water Quality Module assesses the quality of surface waters that receive discharges of
the evaluated wastestreams by comparing estimated pollutant concentrations in the water column
25 The EPA estimates that 18 of 70 coal-fired power plants discharging FGD wastewater (26 percent) may conclude
that the VIP for FGD wastewater under Option 2 is the least costly option. The Supplemental TDD describes how
the EPA estimated which technology would be the least costly for each plant.
26 The Supplemental EA encompasses a total of 112 immediate receiving waters and loadings from 112 coal-fired
power plants (some of which discharge to multiple receiving waters). The IRW Model, which excludes the Great
Lakes and estuaries, analyzes a total of 106 immediate receiving waters and loadings from 105 coal-fired power
plants.
27 The net change represents the change in benchmark value exceedances under each regulatory option relative to
baseline. Under Regulatory Options 2, 3, and 4, there are scenarios where some receiving waters no longer have
exceedances observed at baseline, and other immediate receiving waters have "new" exceedances. For example,
under Regulatory Option 4, increased discharges of bottom ash transport water result in a net increase in
exceedances despite the incorporation of membrane treatment for FGD wastewater.
4-4
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
to the National Recommended Water Quality Criteria (NRWQC) and drinking water maximum
contaminant levels (MCLs) under baseline and each regulatory option. The module considers
modeled exceedances of the Freshwater Acute NRWQC, Freshwater Chronic NRWQC, Human
Health Water and Organism NRWQC, Human Health Organism Only NRWQC, and drinking
water MCL. Table 4-3 summarizes the Water Quality Module results.
Table 4-3. Modeled IRWs with Exceedances of NRWQCs and MCLs under Baseline and
Four Regulatory Options
\\ ater Qu;ili(> l.\ alualion
Denchmark
Niimher of Modeled IRWs I-Acceding Denchmark Value
(Difference Kclali\c lo liaseline)
Baseline
Option 1
Option 2
Option 3
Option 4
I'rcbhw aler Acule \k\YQC
(I
(+2)
(I
(0)
(I
(0)
(I
(0)
Freshwater Chronic NRWQC
0
10
(+10)
3
(+3)
2
(+2)
2
(+2)
Human Health Water and
Organism NRWQC
9
20
(+11)
17
(+8)
16
(+7)
13
(+4)
Human Health Organism Only
NRWQC
4
9
(+5)
8
(+4)
7
(+3)
7
(+3)
Drinking Water MCL
1
3
(+2)
3
(+2)
2
(+1)
1
(0)
Total Number of Unique
Immediate Receiving Waters b
9
21
(+12)
17
(+8)
16
(+7)
13
(+4)
Source: ERG, 2019i.
Acronyms: IRW (immediate receiving water); MCL (maximum contaminant level); NRWQC (National
Recommended Water Quality Criteria).
a - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters
and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters),
b - Total may not equal the sum of the individual values because some immediate receiving waters have multiple
types of exceedances.
Table 4-4 presents the number of immediate receiving waters with exceedances of any NRWQC
or MCL by pollutant.
4-5
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-4. Modeled IRWs with Exceedances of Any NRWQC or MCL, by Pollutant
under Baseline and Four Regulatory Options
Modeled Number of IRWs l.\m-din» NUWQC or \l( l. (l)iHVmicc Rdati\e to
Pollutant
liasclini')
liasclinc
Option 1
Option 2
Option 3
Option 4
Arsenic
9
20
17
16
13
(+11)
(+8)
(+7)
(+4)
Cadmium
0
0
1
0
0
(0)
(+1)
(0)
(0)
Copper
0
0
1
0
0
(0)
(+1)
(0)
(0)
Lead
0
1
2
1
1
(+1)
(+2)
(+1)
(+1)
Mercury
0
0
0
0
0
(0)
(0)
(0)
(0)
Nickel
0
0
1
0
0
(0)
(+1)
(0)
(0)
Selenium
0
10
3
2
2
(+10)
(+3)
(+2)
(+2)
Thallium
4
5
4
3
1
(+1)
(0)
(-1)
(-3)
Zinc
0
0
0
0
0
(0)
(0)
(0)
(0)
Any Pollutantb
9
21
17
16
13
(+12)
(+8)
(+7)
(+4)
Source: ERG, 2019i.
Acronyms: IRW (immediate receiving water); MCL (maximum contaminant level); NRWQC (National
Recommended Water Quality Criteria).
a - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters
and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters),
b - Total may not equal the sum of the individual values because some immediate receiving waters have
exceedances for multiple pollutants.
The Water Quality Module results described above are based on estimated annual average
loadings and flow rates. As described in Section 3.4, the EPA also performed a water quality
analysis using estimated monthly pollutant loadings (of the same nine pollutants evaluated in the
Water Quality Module) and monthly surface water flow rates to assess the significance of
monthly variability in the modeled water quality impacts. Table 4-5 presents the number of
immediate receiving waters with modeled exceedances of each water quality benchmark for the
best-case analysis and exceedances of Freshwater Acute and Chronic NRWQCs for the worst-
case analysis.28
28 The EPA did not consider the Human Health Water and Organism NRWQC, Human Health Organism Only
NRWQC, and Drinking Water MCL when evaluating worst-case monthly outputs because these benchmark values
are based on longer-term (i.e., lifetime) exposure.
4-6
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-5. Modeled IRWs with Exceedances of NRWQCs and MCLs under Baseline and
Four Regulatory Options: Best- and Worst-Case Monthly Scenarios
\\ ater Quality l.\ alualion
lienchmark
Modeled Number of IRWs l.\ceedin» NRWQC or \l( l
(DilTerence Kelali\e lo liaseline)
Baseline
Option 1
Option 2
Option 3
Option 4
Best-Case Monthly Scenario (Lowest Ratio ojLoadings lo 1'low Rate)
Freshwater Acute NRWQC
0
0
(0)
0
(0)
0
(0)
0
(0)
Freshwater Chronic NRWQC
0
4
(+4)
1
(+1)
0
(0)
0
(0)
Human Health Water and
Organism NRWQC
4
8
(+4)
6
(+2)
6
(+2)
6
(+2)
Human Health Organism Only
NRWQC
2
4
(+2)
5
(+3)
4
(+2)
2
(0)
Drinking Water MCL
0
0
(0)
0
(0)
0
(0)
0
(0)
Any Water Quality
Evaluation Benchmark b
4
8
(+4)
6
(+2)
6
(+2)
6
(+2)
Worst-Case Monthly Scenario (Highest Ratio of Loadings to Flow Rate)
Freshwater Acute NRWQC
0
3
(+3)
1
(+1)
0
(0)
0
(0)
Freshwater Chronic NRWQC
2
17
(+15)
8
(+6)
6
(+4)
5
(+3)
Any Water Quality
Evaluation Benchmark b
2
17
(+15)
8
(+6)
6
(+4)
5
(+3)
Source: ERG, 2019j.
Acronyms: IRW (immediate receiving water); MCL (maximum contaminant level); NRWQC (National
Recommended Water Quality Criteria).
a - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters
and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters),
b - Total may not equal the sum of the individual values because some immediate receiving waters have multiple
types of exceedances.
The results of the monthly analysis demonstrate some similarities with the results of the annual
average analysis:
• Under the worst-case monthly analysis, the total number of immediate receiving
waters with exceedances of the Freshwater Chronic NRWQC increases under all
options (relative to baseline).
• Total arsenic (for the Human Health Water and Organism NRWQC in the best-case
analysis) and total selenium (for the Freshwater Chronic NRWQC in both analyses)
remain the primary drivers of the water quality exceedances (ERG, 2019j).
The monthly analysis also provides information beyond that provided by the annual average
analysis:
• Most worst-case months occur during the summer, whereas most best-case months
occur during the winter and early spring.
4-7
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
• Under the best-case monthly analysis, approximately one-third to one-half of
immediate receiving waters with exceedances in the annual average analysis continue
to have exceedances of at least one water quality benchmark value.
• Under the worst-case monthly analysis, many receiving waters (more than were
identified in the annual average analysis) experience exceedances of the Freshwater
Chronic NRWQC. This suggests the potential for impacts on aquatic life during
certain periods characterized by low flows, high loadings, or a combination of the
two.
These results suggest that seasonal water quality impacts from discharges of the evaluated
wastestreams, and their increase under the regulatory options, may be more prevalent than
indicated by the annual average analysis (ERG, 2019j).
The EPA evaluated whether there are geographic clusters of immediate receiving waters whose
worst-case months occur during the same time of year, indicating the potential for seasonal
cumulative effects in the affected watersheds. Figure 4-1 illustrates the worst-case month
identified for each immediate receiving water in the supplemental monthly analysis. This shows
the following geographic patterns:
• Nearly the entire length of the Ohio River has clusters of immediate receiving waters
with worst-case months during July, August, and September.
• The Illinois River has a cluster of immediate receiving waters with worst-case months
in September, October, and November.
• Several other parts of the country have smaller clusters of immediate receiving waters
with worst-case months during the same season. Examples include the Mobile River
watershed in southern Alabama (August); the Wabash River watershed in southwest
Indiana (October); and the Santee River watershed in South Carolina (July-
September).
The watersheds referenced above are examples of areas that could potentially experience adverse
seasonal cumulative effects due to concurrent, or nearly concurrent, discharges of evaluated
wastestreams from multiple plants. This dynamic could be particularly pronounced during
summer and early autumn. Swimming, fishing, and boating in local waterways are generally
more common during these seasons, potentially increasing opportunities for exposure to
degraded water quality conditions in the immediate receiving waters.
Additionally, fish species that spawn in the affected waterways during these periods (including
federally threatened or endangered species) could have an increased potential for adverse
impacts from pollutant exposure, since the timing of their sensitive life stages would align with
worst-case water quality conditions. For example, the Northern madtom (Noturus stigmosus), a
small catfish, lives in tributaries along the Ohio River, including the lower Ohio watershed; it
spawns in June and July and is currently listed as endangered in Ohio. Since the Northern
madtom spawns during worst-case conditions in the Ohio River watershed, it could experience
reduced fecundity and its population could be further compromised by seasonal fluctuations in
pollutant loadings from coal-fired power plants.
4-8
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Worst-Case Month
• January • July • October
• Fcburary • August • November
• May September • December
Figure 4-1. Worst-Case Months for Water Quality Conditions in Immediate Receiving
Waters
Data regarding actual monthly loadings were not available for this analysis. This analysis is
intended only to illustrate that seasonal impacts resulting from discharges of the evaluated
wastestreams, and the increase in those impacts under Option 2, may be more extensive than
shown in the annual average analysis, and that some watersheds (not necessarily the examples
noted in this discussion) could experience increased seasonal impacts depending on the seasonal
discharge patterns of coal-fired power plants in those watersheds.
4.2.2 Wildlife Module
The IRW Wildlife Module compares sediment pollutant concentrations to threshold effect
concentrations (TECs) for sediment biota; calculates the bioaccumulation of pollutants in trophic
level 3 (T3) and trophic level 4 (T4) fish tissue; and compares these tissue concentrations to no
effect hazard concentrations (NEHCs) for minks and eagles. This analysis expands on the
evaluation of potential wildlife impacts based on the Freshwater Chronic and Acute NRWQCs in
the Water Quality Module.
Table 4-6 presents the number of immediate receiving waters with modeled exceedances of the
TECs and NEHCs under baseline and changes in those exceedances under the regulatory options.
Results are presented for all pollutants in aggregate and individually for selenium and mercury,
which cause most of the exceedances.
4-9
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-6. Modeled IRWs with Exceedances of TECs and NEHCs under Baseline and
Four Regulatory Options
\\ ildlife
Modeled Number of IRW s r.\ccc(lin» TI C or M.IK
r.\iilu;ilion
Pollutant
(Difference Kclati\cto Baseline)
Benchmark
Baseline
Option 1
Option 2
Option 3
Option 4
Sediment
Any Pollutant
2
20
10
7
6
TEC
(+18)
(+8)
(+5)
(+4)
Nickel
0
3
4
3
2
(+3)
(+4)
(+3)
(+2)
Selenium
2
20
10
7
6
(+18)
(+8)
(+5)
(+4)
Mercury
0
5
4
3
2
(+5)
(+4)
(+3)
(+2)
Fish Ingestion
Any Pollutant
0
10
4
2
2
NEHC for
(+10)
(+4)
(+2)
(+2)
Minks
Selenium
0
9
3
1
1
(+9)
(+3)
(+1)
(+1)
Mercury
0
3
3
2
2
(+3)
(+3)
(+2)
(+2)
Fish Ingestion
Any Pollutant
1
11
7
5
3
NEHC for
(+10)
(+6)
(+4)
(+2)
Eagles
Selenium
0
9
3
1
1
(+9)
(+3)
(+1)
(+1)
Mercury
1
6
6
5
3
(+5)
(+5)
(+4)
(+2)
Any Wildlife Pollutant
2
20
10
7
6
Benchmark for Any Pollutantb
(+18)
(+8)
(+5)
(+4)
Source: ERG, 2019i.
Acronyms: IRW (immediate receiving water); TEC (Threshold Effect Concentration); NEHC (No Effect Hazard
Concentration).
a - Appendix F presents results for all individual modeled pollutants.
b - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters
and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters),
c - Total may not equal the sum of the individual values because some immediate receiving waters have multiple
types of exceedances.
4.2.3 Human Health Module
The IRW Human Health Module evaluates non-cancer and cancer human health impacts among
various human cohorts (recreational and subsistence fishers; children and adults; and different
race categories) from consuming fish caught from immediate receiving waters that are
contaminated by discharges of the evaluated wastestreams. The module uses oral reference doses
(RfDs) to evaluate changes in non-cancer health risks, and a lifetime excess cancer risk (LECR)
benchmark value of one-in-a-million, or 10"6. This analysis expands on the evaluation of
potential human health impacts based on the NRWQCs and MCLs in the Water Quality Module.
Under baseline, the EPA estimates the average daily doses (for one or more pollutants) among
subsistence fishers exceed the oral RfDs (non-cancer) in 6 to 8 percent of immediate receiving
waters, depending on the age group evaluated. Average daily doses among recreational fishers
exceed oral RfDs in 4 to 6 percent of immediate receiving waters. The exceedances are primarily
driven by thallium and mercury (as methylmercury). The lower prevalence of exceedances
4-10
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
among recreational fishers is primarily due to their lower average fish tissue consumption rates.
These results suggest that fish in immediate receiving waters can have non-cancer health effects
on surrounding fisher populations.
The EPA estimates that the number of immediate receiving waters contributing to oral RfD (non-
cancer) exceedances increases for all standard cohorts (i.e., cohorts that are not split into
different race categories) under all regulatory options. Under Option 2, the EPA estimates that
pollutant concentrations in fish tissue increase for all modeled pollutants relative to baseline
concentrations. The pollutants that cause increased potential for non-cancer health effects based
on oral RfDs are mercury (as methylmercury), selenium, thallium, and, to a lesser degree,
cadmium and zinc. For example, the number of immediate receiving waters with methylmercury
concentrations that pose a non-cancer risk to humans increases from 3 to 6 percent (under
baseline) to 7 to 16 percent (under Option 2), with the specific increase depending on the cohort.
Table 4-7 presents the number of immediate receiving waters where the average daily dose of the
modeled pollutants exceeds the corresponding oral RfD.
Although the Supplemental EA did not directly assess the potential non-cancer health effects
posed by lead,29 Option 2 increases the annual loadings of lead to the environment by 693
pounds compared to baseline. The monetized human health effects associated with changes in
lead discharges are discussed in the BCA Report.
Under baseline, the EPA estimates that none of the immediate receiving waters would contain
fish contaminated with inorganic arsenic that present cancer risks greater than the LECR
benchmark value of one in one million for the most sensitive, standard cohort. The EPA
calculates that all of the regulatory options increase the number of immediate receiving waters
containing fish with inorganic arsenic levels that exceed the selected LECR threshold for adult
recreational and subsistence fishers. Option 2 also increases the number of exceedances for the
child recreational and subsistence fisher cohort. Table 4-8 presents the number of immediate
receiving waters where the LECR for inorganic arsenic exceeds one-in-a-million. The BCA
Report further discusses the EPA's assessment of potential cancer impacts for human
populations.
29 The EPA has not developed an RfD for lead because adverse health effects "may occur at blood lead levels so low
as to be essentially without a threshold" (U.S. EPA, 2004).
4-11
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-7. Modeled IRWs with Exceedances of Oral RfD (Non-Cancer Human Health
Effects) under Baseline and Four Regulatory Options
Alii' iiiul Tjpe ill'
l-'isli ( oiisii in pi icin
Cohort
Pollutant
Modeled Number of IRWs r.\cccdin» Oral Kl'l)
(Difference Rclati\c to liaseline)
liaseline
Option 1
Option 2
Option 3
Option 4
Child - Recreational
Any Pollutant
6
15
(+9)
12
(+6)
10
(+4)
8
(+2)
Mercury (as
methylmercury)
5
11
(+6)
10
(+5)
9
(+4)
8
(+3)
Selenium
0
9
(+9)
3
(+3)
1
(+1)
1
(+1)
Thallium0
6
9
(+3)
8
(+2)
7
(+1)
4
(-2)
Child - Subsistence
Any Pollutant
9
23
(+14)
19
(+10)
14
(+5)
11
(+2)
Mercury (as
methylmercury)
6
19
(+13)
17
(+11)
14
(+8)
11
(+5)
Selenium
2
16
(+14)
9
(+7)
5
(+3)
3
(+1)
Thallium0
9
14
(+5)
11
(+2)
10
(+1)
7
(-2)
Adult - Recreational
Any Pollutant
4
10
(+6)
7
(+3)
7
(+3)
7
(+3)
Mercury (as
methylmercury)
3
10
(+7)
7
(+4)
7
(+4)
7
(+4)
Selenium
0
6
(+6)
2
(+2)
1
(+1)
1
(+1)
Thallium0
4
6
(+2)
5
(+1)
4
(0)
2
(-2)
Adult - Subsistence
Any Pollutant
6
16
(+10)
12
(+6)
10
(+4)
8
(+2)
Mercury (as
methylmercury)
6
14
(+8)
12
(+6)
10
(+4)
8
(+2)
Selenium
0
10
(+10)
4
(+4)
2
(+2)
1
(+1)
Thallium0
6
10
(+4)
8
(+2)
8
(+2)
6
(0)
Any Pollutant and Age/Consumption
Cohortd
9
23
(+14)
19
(+10)
14
(+5)
11
(+2)
Source: ERG, 2019i.
Acronyms: IRW (immediate receiving water); RfD (reference dose),
a - Appendix F presents results for each individual modeled pollutant.
b - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters
and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters),
c - The EPA used the chronic oral exposure value cited in U.S. EPA, 2010a for thallium chloride as the RfD.
d - Total may not equal the sum of the individual values because some immediate receiving waters have
exceedances for multiple pollutants and/or cohorts.
4-12
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-8. Modeled IRWs with LECR Greater Than One-in-a-Million (Cancer Human
Health Effects) under Baseline and Four Regulatory Options
Age
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-9. Modeled IRWs with Exceedances of Oral RfD (Non-Cancer Human Health Effects), by Race Category, under
Baseline and Four Regulatory Options
Alio iiiid Tjpe of
l-'isli ( oiisii in pi icin
Cohort
Race (;i leuon
Modeled Number of IRWs l.\eeedin» Or;d KID
(Difference Kehili\e lo liiiseline)
liiiseliue
Option 1
Option 2
Option 3
Option 4
Mercury (as melhylmercuryj
Recreational
(All age cohorts)
Non-Hispanic White
3
10 (+7)
7 (+4)
7 (+4)
7 (+4)
Non-Hispanic Black
3
10 (+7)
7 (+4)
7 (+4)
7 (+4)
Mexican-American
3
11 (+8)
8 (+5)
8 (+5)
8 (+5)
Other Hispanic
3
10 (+7)
7 (+4)
7 (+4)
7 (+4)
Other, Including Multiple Races
3
11 (+8)
8 (+5)
8 (+5)
8 (+5)
Subsistence
(All age cohorts)
Non-Hispanic White
5
14 (+9)
11 (+6)
10 (+5)
8 (+3)
Non-Hispanic Black
6
14 (+8)
12 (+6)
10 (+4)
8 (+2)
Mexican-American
6
16 (+10)
14 (+8)
11 (+5)
9 (+3)
Other Hispanic
6
16 (+10)
14 (+8)
11 (+5)
9 (+3)
Other, Including Multiple Races
6
17 (+11)
15 (+9)
12 (+6)
10 (+4)
Selenium
Recreational
(All age cohorts)
Non-Hispanic White
0
6 (+6)
2 (+2)
1 (+1)
1 (+1)
Non-Hispanic Black
0
6 (+6)
2 (+2)
1 (+1)
1(+1)
Mexican-American
0
6 (+6)
2 (+2)
1 (+1)
1(+1)
Other Hispanic
0
6 (+6)
2 (+2)
1 (+1)
1 (+1)
Other, Including Multiple Races
0
6 (+6)
2 (+2)
1 (+1)
1 (+1)
Subsistence
(All age cohorts)
Non-Hispanic White
0
10 (+10)
4 (+4)
2 (+2)
1 (+1)
Non-Hispanic Black
0
10 (+10)
4 (+4)
2 (+2)
1(+1)
Mexican-American
0
12 (+12)
6 (+6)
4 (+4)
2 (+2)
Other Hispanic
0
12 (+12)
6 (+6)
4 (+4)
2 (+2)
Other, Including Multiple Races
1
12 (+11)
6 (+5)
4 (+3)
2 (+1)
4-14
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-9. Modeled IRWs with Exceedances of Oral RfD (Non-Cancer Human Health Effects), by Race Category, under
Baseline and Four Regulatory Options
Alio iiiid Tjpe of
l-'isli ( oiisii in pi icin
Cohort
Race (;i leuon
Modeled Number of IRW s l.\eeedin» ()r;il Kl'l)
(Difference Kehili\e lo liiiseline)
liiiseliue
Option 1
Option 2
Option 3
Option 4
Thallium
Recreational
(All age cohorts)
Non-Hispanic White
4
6 (+2)
5(+l)
4(0)
2 (-2)
Non-Hispanic Black
4
6 (+2)
5(+l)
4(0)
2 (-2)
Mexican-American
5
7 (+2)
6 (+1)
5(0)
2 (-3)
Other Hispanic
4
6 (+2)
5(+l)
4(0)
2 (-2)
Other, Including Multiple Races
5
7 (+2)
6 (+1)
5(0)
2 (-3)
Subsistence
(All age cohorts)
Non-Hispanic White
6
10 (+4)
8 (+2)
8 (+2)
5 (-1)
Non-Hispanic Black
6
10 (+4)
8 (+2)
8 (+2)
6(0)
Mexican-American
6
11 (+5)
9 (+3)
9 (+3)
7 (+1)
Other Hispanic
6
11 (+5)
9 (+3)
9 (+3)
7 (+1)
Other, Including Multiple Races
8
14 (+6)
10 (+2)
10 (+2)
7 (-1)
Source: ERG, 2019i.
Acronyms: IRW (immediate receiving water); RfD (reference dose).
A - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters and loadings from 105 coal-fired power
plants (some of which discharge to multiple receiving waters).
4-15
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
The EPA also compared T4 fish tissue pollutant concentrations to fish consumption advisory
screening values to assess the potential for discharges of the evaluated wastestreams to cause or
contribute to fish advisories and pose a human health risk.30 Based on the modeling results, up to
6 percent of the evaluated immediate receiving waters may contain fish with contamination
levels that could trigger advisories for recreational and/or subsistence fishers under baseline; this
increases to approximately 13 percent under Option 2. Mercury and selenium are the pollutants
most likely to exceed screening values. Table 4-10 presents the number and percentage of
immediate receiving waters where the modeled T4 fish tissue concentrations exceed screening
values used for fish advisories.31
Table 4-10. Comparison of Modeled T4 Fish Tissue Concentrations to Fish Advisory
Screening Values under Baseline and Four Regulatory Options
Pollutant
Screening
\ alue (ppm)
Niimher of IKWs willi Modeled 14 l-'isli 1 issue Concentrations
l-Aceedinii Screening Value (Difference Kclati\e to Baseline)
Baseline
Option 1
Option 2
Option 3
Option 4
Recreational Fishers
Arsenic (as
inorganic arsenic)
0.026
0
0(0)
0(0)
0(0)
0(0)
Cadmium
4
0
0(0)
0(0)
0(0)
0(0)
Mercury (as
methylmercury)
0.4
2
7 (+5)
7 (+5)
6 (+4)
5 (+3)
Selenium
20
0
5 (+5)
2 (+2)
1 (+1)
1 (+1)
Total for Any Pollutant in
Evaluated Wastestreams b
2
8 (+6)
7 (+5)
6 (+4)
5 (+3)
Subsistence Fishers
Arsenic
0.00327
0
0(0)
0(0)
0(0)
0(0)
Cadmium
0.491
0
0(0)
1 (+1)
0(0)
0(0)
Mercury (as
methylmercury)
0.049
6
16 (+10)
14 (+8)
11 (+5)
9 (+3)
Selenium
2.457
0
12 (+12)
6 (+6)
4 (+4)
2 (+2)
Total for Any Pollutant in
Evaluated Wastestreams b
6
18 (+12)
14 (+8)
11 (+5)
9 (+3)
Sources: ERG, 2019i.
Acronyms: IRW (immediate receiving water); ppm (parts per million); T4 (trophic level 4).
A - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters
and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters),
b - Total may not equal the sum of the individual values because some immediate receiving waters are impaired for
multiple pollutants.
30 For this analysis, the EPA used the fish consumption advisory screening values from EPA's Guidance for
Assessing Chemical Contaminant Data for Uses in Fish Advisories, Volume 1 (U.S. EPA, 2000a).
31 As described in Section 4.4.2, none of the immediate receiving waters are under fish consumption advisories for
arsenic, cadmium, or selenium; each advisory screening value exceedance shown in Table 4-10 for these pollutants
therefore indicates a "new" receiving water of concern that may warrant additional monitoring and/or evaluation of
human health risk. Similarly, for mercury under Option 2, 9 of the 14 immediate receiving waters with modeled
exceedances of the advisory screening value are "new" receiving waters of concern that are not under fish
consumption advisories for mercury.
4-16
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Section 4 — Results of the Supplemental Quantitative Environmental Assessment
4.3 Impacts in Downstream Surface Waters
The EPA performed an analysis of surface waters downstream from the immediate receiving
water for each plant that discharges the evaluated wastestreams. The downstream analysis uses
the outputs from a separate pollutant fate and transport model (see the BCA Report for a
description of the model) to assess potential water quality, wildlife, and human health impacts in
approximately 10,400 river miles of downstream surface waters. The methodology, which uses
estimated annual average pollutant loadings and surface water flow rates, is summarized in
Section 3.5 of this report and presented in further detail in the memorandum "Downstream
Modeling Analysis and Supporting Documentation for the 2019 Steam Electric Supplemental
Environmental Assessment" (ERG, 2019g).
Table 4-11 presents the results of this downstream analysis. This table lists each of the water
quality, wildlife, and human health benchmark values used in the IRW Model32 and indicates the
total length of downstream surface waters for which the EPA calculated an exceedance of a
benchmark value for at least one of the modeled pollutants.
For each benchmark value with modeled exceedances under baseline, the analysis shows that the
total length of downstream surface waters with exceedances increases under Option 2. For
example, the length of downstream surface waters with at least one exceedance of the Human
Health Water and Organism NRWQC increases from 64.6 miles (baseline) to 187 miles (Option
2), and exceedances of the oral RfD increase from 101 miles (baseline) to 198 miles (Option 2)
for the child subsistence fisher cohort. Option 2 also results in downstream exceedances of some
benchmark values that do not have modeled exceedances under baseline (e.g., the Freshwater
Acute and Chronic NRWQCs and the LECR).
32 The water quality outputs used in the downstream analysis were derived from a pollutant fate and transport model
that does not simulate pollutant partitioning to the benthic layer; therefore, this analysis does not include
comparisons to the sediment TEC.
4-17
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-11. Modeled Downstream River Miles with Exceedances of Any Pollutant
Evaluation Benchmark Value under Baseline and Four Regulatory Options
11 \ iiliiiilioii Benchm;irk
Modeled Number of Downstream Ri\er Miles l-'.\ceedin;i lieiielniiiirk
Value (Difference Rel;i(i\e to liiiseline)
ISiiseline
Option 1
Option 2
Option 3
Option 4
Water Duality Results
Freshwater Acute NRWQC
0.0
4.66
(+4.66)
0.372
(+0.372)
0.0
(0)
0.0
(0)
Freshwater Chronic NRWQC
0.0
26.1
(+26.1)
6.59
(+6.59)
2.51
(+2.51)
2.51
(+2.51)
Human Health Water and
Organism NRWQC
64.6
143
(+78.5)
187
(+122)
127
(+62.2)
77.2
(+12.6)
Human Health Organism Only
NRWQC
19.4
43.4
(+23.9)
68.2
(+48.8)
36.4
(+16.9)
30.8
(+11.4)
Drinking Water MCL
2.56
7.84
(+5.28)
4.62
( :()(.)
2.19
(-0.372)
0.0
(-2.56)
Wildlife Results
1'ish Ingestion \L11C for Minks
0.3 "J"
49.1
(+48.8)
JNi.3
(+19.9)
8.4:
(+8.04)
5.10
(+5.25)
Fish Ingestion NEHC for Eagles
15.9
69.0
(+53.1)
42.8
(+26.8)
32.4
(+16.5)
27.9
(+11.9)
Iluman Ilealth Results \on-( 'ancer
Oral RfD for Child (Recreational)
42.6
90.4
(+47.8)
125
(+82.4)
63.2
(+20.6)
47.2
(+4.57)
Oral RfD for Adult (Recreational)
28.5
53.8
(+25.3)
77.3
(+48.8)
45.4
(+16.9)
39.9
(+11.4)
Oral RfD for Child (Subsistence)
101
179
(+77.8)
198
(+96.9)
127
(+26.3)
77.0
(-23.9)
Oral RfD for Adult (Subsistence)
50.1
110
(+60.3)
143
(+92.9)
68.2
(+18.1)
47.2
(-2.99)
I luman I lealth Results ("ancer
LECR for Child (Recreational)
0.0
0.0
(0)
0.0
(0)
0.0
(0)
0.0
(0)
LECR for Adult (Recreational)
0.0
0.0
(0)
2.06
(+2.06)
0.0
(0)
0.0
(0)
LECR for Child (Subsistence)
0.0
0.0
(0)
2.06
(+2.06)
0.0
(0)
0.0
(0)
LECR for Adult (Subsistence)
0.0
2.51
(+2.51)
4.56
(+4.56)
2.51
(+2.51)
2.51
(+2.51)
Source: ERG, 2019g.
Acronyms: LECR (lifetime excess cancer risk); MCL (maximum contaminant level); NEHC (no effect hazard
concentration); NRWQC (National Recommended Water Quality Criteria); RfD (reference dose).
Note: River miles are rounded to three significant figures. As part of this analysis, the EPA evaluated approximately
10,400 river miles of surface waters downstream of immediate receiving waters.
4-18
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
4.4 Discharges to Impaired Waters and Fish Consumption Advisory Waters
Discharges of the evaluated wastestreams to Clean Water Act 303(d) impaired waters and fish
consumption advisory waters33 may contribute to water quality impairments, increased health
risk associated with consuming fish, and a reduction in the extent of viable downstream fisheries.
Table 4-12 summarizes the number of immediate receiving waters that are classified as either a
303(d) impaired water or a fish consumption advisory water under baseline and each regulatory
option. Sections 4.4.1 and 4.4.2 present the results of the EPA's assessment of immediate
receiving waters that are 303(d) impaired waters or fish consumption advisory waters,
respectively.34
Table 4-12. IRWs Identified as Clean Water Act 303(d) Impaired Waters or Fish
Consumption Advisory Waters under Baseline and Four Regulatory Options
Number of IRWs (DilTcmicc Rcl;ili\o to B;isoliuo)
liiisoliuo
Option 1
Option 2
Option 3
Option 4
Impaired water
39
59 (+20)
53 (+14)
51 (+12)
37 (-2)
Subset impaired for one or more
pollutants associated with the evaluated
wastestreams.
26
42 (+16)
35 (+9)
35 (+9)
24 (-2)
Fish consumption advisory water
50
67 (+17)
55 (+5)
54 (+4)
32 (-18)
Subset with a fish consumption
advisory for one or more pollutants
associated with the evaluated
wastestreams.
37
46 (+9)
35 (-2)
35 (-2)
18 (-19)
Source: ERG, 2019h.
4.4.1 Impaired Waters
The EPA determined that more than half (60 of 112) of the immediate receiving waters analyzed
in the Supplemental EA are 303(d) impaired waters.35 As shown in Table 4-13, 26 of the
immediate receiving waters under baseline (23 percent) and 35 of the immediate receiving
waters under Option 2 (31 percent) are impaired for a pollutant present in the evaluated
wastestreams. Figure 4-2, Figure 4-3, and Figure 4-4 present the locations of immediate
receiving waters that are classified as impaired by high concentrations of mercury, metals (other
than mercury), and nutrients, respectively.
33 Fish consumption advisory waters are waterbodies for which states, territories, and authorized tribes have issued
fish consumption advisories, indicating that pollutant concentrations in the tissues of fish inhabiting those waters are
considered unsafe to consume.
34 See the memorandum "Proximity Analyses and Supporting Documentation for the 2019 Steam Electric
Supplemental Environmental Assessment" (ERG, 2019h) for a description of the methodology used to evaluate the
proximity of coal-fired power plants to 303(d) impaired waters, fish consumption advisory waters, and other
sensitive environments.
35 See the memorandum "Proximity Analyses and Supporting Documentation for the 2019 Steam Electric
Supplemental Environmental Assessment" (ERG, 2019h) for a complete list of the impairment categories identified
in the EPA's 303(d) waters proximity analysis.
4-19
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-13. IRWs Listed as 303(d) Impaired for Pollutants Present in the Evaluated
Wastestreams under Baseline and Four Regulatory Options
Polliiliinl ( iiusinii
1 m p:ii rim-iil
Nil in hoi* or ii
liiisolino
i\\ s Listed :is J
Option 1
03(d) 1 ill |);ii led
lo liiisolino)
Option 2
\\ ;Kors (DilTor
Option 3
nice Rcl;i(i\c
Option 4
\leivui>
i:
:: i hi)
1S ( (1)
1S ( (1)
14 ( 2)
Metals, other than mercury b
9
14 (+5)
12 (+3)
12 (+3)
8 (-1)
Nutrients
8
12 (+4)
11 (+3)
11 (+3)
7 (-1)
TDS, including chlorides
1
2 (+1)
2 (+1)
2 (+1)
2 (+1)
Total for Any Pollutant in
Evaluated Wastestreams 0
26
42 (+16)
35 (+9)
35 (+9)
24 (-2)
Source: ERG, 2019h.
Acronyms: IRW (immediate receiving water); TDS (total dissolved solids).
a - For this proximity analysis, the EPA evaluated 112 immediate receiving waters that receive discharges of the
evaluated wastestreams under any scenario, either directly or indirectly via a POTW. Of these 112 immediate
receiving waters, 69 receive discharges of the evaluated wastestreams under baseline, 111 under Option 1, 96
under Option 2, 94 under Option 3, and 69 under Option 4.
b - Of the 14 immediate receiving waters classified as impaired for "metal, other than mercury" under baseline or
any regulatory option, 11 immediate receiving waters are specifically listed as impaired for one or more of the
following individual pollutants evaluated in the Supplemental EA: cadmium (1), chromium (1), copper (2), iron
(6), lead (3), manganese (1), selenium (1), and zinc (1).
c - Total may not equal the sum of the individual values because some immediate receiving waters are impaired
for multiple pollutants.
4-20
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Immediate Receiving Waters with Hg Impairment
® Baseline Discharges of Evaluated Waslcslrcams
0 Oplion 2 Discharges of Evaluated Wastcstrcams
® Baseline & Option 2 Discharges of Evaluated Wastestreams
O Discharge of Evaluated Wastcstrcams Under Options 1.3, or 4 Only
Figure 4-2. Immediate Receiving Waters Impaired by Mercury
0
e
Immediate Receiving Waters with Metals Impairment (Not Hg)
® Baseline Discharges of Evaluated Wastestreams
® Oplion 2 Discharges of Evaluated Wastestreams
® Baseline & Oplion 2 Discharges of Evaluated Wastestreams
O Discharge of Evaluated Wastcstrcams Under Options 1, 3. or 4 Only
Figure 4-3. Immediate Receiving Waters Impaired by Metals, Other Than Mercury
4-21
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Immediate Receiving Waters with Nutrients Impairment
® Baseline Discharges of* Evaluated Wastestreams
© Option 2 Discharges of Evaluated Wastestreams
© Baseline & Option 2 Discharges of Evaluated Wastestreams
O Discharge of Evaluated Wastestreams Under Options 1, 3, or 4 Only
Figure 4-4. Immediate Receiving Waters Impaired by Nutrients
Option 2 has a mixed effect on the loadings of pollutants to waters that are already impaired for
those pollutants, increasing estimated loadings for some pollutants and decreasing them for
others. Once requirements under Option 2 have been met at all plants (i.e., by December 31,
2028), the EPA estimates the following net changes relative to baseline in pollutant loadings to
impaired waters:
• Nitrogen increase of 23,000 lb/yr and phosphorus increases of 151 Ib/yr to nutrient-
impaired waters.
• Phosphorus increase of 116 lb/yr to phosphorus-impaired waters.
• Mercury increase of 1.6 lb/yr to mercury-impaired waters.
• Net changes in loadings to receiving waters impaired for a metal (except mercury):
Aluminum increase of 1,220 lb/yr.
Arsenic decrease of 5.15 lb/yr.
- Barium decrease of 359 lb/yr.
- Beryllium decrease of 5.45 lb/yr.
Cadmium decrease of 15.7 lb/yr.
Calcium decrease of 7,520,000 lb/yr.
Chromium decrease of 16.1 lb/yr.
Cobalt decrease of 19.5 lb/yr.
4-22
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Copper decrease of 7.50 lb/yr.
Iron increase of 902 lb/yr.
- Lead increase of 7.00 lb/yr.
- Magnesium decrease of 13,600,000 lb/yr.
- Manganese decrease of 50,600 lb/yr.
- Molybdenum decrease of 453 lb/yr.
Nickel increase of 9.21 lb/yr.
- Potassium increase of 3 9,100 lb/yr.
Selenium increase of 1.18 lb/yr.
Silicon increase of 16,300 lb/yr.
Sodium decrease of 885,000 lb/yr.
Strontium increase of 2,860 lb/yr.
Thallium decrease of 37.7 lb/yr.
Titanium increase of 33.8 lb/yr.
Vanadium decrease of 31.2 lb/yr.
- Zinc decrease of 13.8 lb/yr.
4.4.2 Fish Consumption Advisories
The EPA determined that 50 of the immediate receiving waters under baseline (45 percent) and
55 of the immediate receiving waters under Option 2 (49 percent) are under fish consumption
advisories.36 As shown in Table 4-14, 37 of the 50 immediate receiving waters (under baseline)
and 35 of the 55 immediate receiving waters (under Option 2) are under an advisory for a
pollutant associated with the evaluated wastestreams. All of these immediate receiving waters
are under fish consumption advisories for mercury. The EPA also reviewed fish consumption
advisories for arsenic, cadmium, chromium, copper, lead, selenium, zinc, and unspecified metals,
but did not identify any immediate receiving waters receiving discharges under baseline or the
regulatory options. Under Option 2, the EPA estimates a 2.52 lb increase in annual mercury
loadings to immediate receiving waters with fish consumption advisories for mercury. Figure 4-5
illustrates the locations of immediate receiving waters with fish consumption advisories for
mercury.
36 See the memorandum "Proximity Analyses and Supporting Documentation for the 2019 Steam Electric
Supplemental Environmental Assessment" (ERG, 2019h) for a complete list of the types of advisories identified in
the EPA's fish consumption advisories proximity analysis, including advisories due to pollutants that are not
associated with the evaluated wastestreams.
4-23
-------
Section 4 — Results of the Supplemental Quantitative Environmental Assessment
Table 4-14. IRWs with Fish Consumption Advisories for Pollutants Present in the
Evaluated Wastestreains under Baseline and Four Regulatory Options
Pollutant Causing Fish
Consumption Advisory
Number of IRWs with Fish Consumption Advisory (Difference Relative to
Baseline)a
Baseline
Option 1
Option 2
Option 3
Option 4
Mercury
37
46 (+9)
35 (-2)
35 (-2)
18 (-19)
Total for Any Pollutant in
Evaluated Wastestreams
37
46 (+9)
35 (-2)
35 (-2)
18 (-19)
Source: ERG, 2019h.
Acronyms: IRW (immediate receiving water).
a - For this proximity analysis, the EPA evaluated 112 immediate receiving waters that receive discharges of the
evaluated wastestreains under any scenario, either directly or indirectly via a POTW. Of these 112 immediate
receiving waters, 69 receive discharges of the evaluated wastestreains under baseline. Ill under Option 1, 96
under Option 2, 94 under Option 3, and 69 under Option 4.
©
Immediate Receiving Waters with Hg Fish Consumption Advisory
© Baseline Discharges of Evaluated Wastestreams
0 Option 2 Discharges of Kvaluated Wastestreams
© Baseline & Option 2 Discharges of Evaluated Wastestreams
O Discharge of Evaluated Wastestreams Under Options 1, 3, or 4 Only
Figure 4-5. Immediate Receiving Waters with Fish Consumption Advisory for Mercury
4-24
-------
Section 5 — References
SECTION 5
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Appendix A —Adverse Impacts from Exposure to Metals and Toxic and Bioaccumulative Pollutants
APPENDIX A
ADVERSE IMPACTS FROM EXPOSURE TO METALS AND
TOXIC AND BIOACCUMULATIVE POLLUTANTS
Table A-l presents example adverse impacts from exposure to elevated concentrations of metals
and toxic and bioaccumulative pollutants, which are present in discharges of the evaluated
wastestreams (flue gas desulfurization (FGD) wastewater and bottom ash transport water) from
coal-fired power plants. The table is not an exhaustive list of adverse impacts but provides
context for an assessment of environmental, ecological, and human health impacts from exposure
to these pollutants. Additional information is available in Environmental Assessment for the
Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point
Source Category (2015 Final EA) (U.S. EPA, 2015a).
A-l
-------
Appendix A —Adverse Impacts from Exposure to Metals and Toxic and Bioaccumulative Pollutants
Table A-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of Metals and Toxic and
Bioaccumulative Pollutants
Polliiliinl
liciichiiiiii'k Value''
Iieuehm;irk Value
I'lmlpoinl''
Poleulial A(l\erse 1 illp;icls
Aluminum
Minimal risk level
(MRL) for intermediate
and chronic oral
exposure is 1.0
milligrams per kilograms
per day (mg/kg/day).
Neurological impacts
Elevated levels of aluminum can adversely impact some species' ability to regulate ions and
can inhibit respiratory functions (U.S. EPA, 2018b). Oral exposures to aluminum in animal
studies show that the nervous system is a sensitive target (ATSDR, 2008a).
High levels of aluminum can also cause brain disease in children with kidney disease and bone
disease in children with kidney disease, and in children taking some medicines containing
aluminum (ATSDR, 2008a).
Arsenic b
MRL for acute oral
exposure is 0.005
mg/kg/day.
Gastrointestinal
impacts
Arsenic tends to bioaccumulate in aquatic communities and potentially impacts higher-
trophic-level organisms. Elevated arsenic tissue concentrations are associated with liver
poisoning, developmental abnormalities, behavioral impairments, metabolic failure, reduced
growth, and appetite loss in aquatic organisms (NRC, 2006; Rowe et al., 2002; U.S. EPA,
2011a).
In humans, arsenic contamination is associated with an increased risk of bladder, lung, and
skin cancer, particularly in inorganic forms. Arsenic is also a potential endocrine disruptor.
Non-cancer impacts from long-term exposure include dermal impacts, developmental effects,
diabetes, cardiovascular disease, and pulmonary disease. Chronic exposure via drinking water
has been associated with excess incidence of miscarriages, stillbirths, preterm births, and low
birth weights (Diamanti-Kandarakis et al., 2009; WHO, 2018).
MRL for chronic oral
exposure is 0.0003
mg/kg/day.
Dermal impacts
Boron
MRL for acute and
intermediate oral
exposure is 0.2
mg/kg/day.
Developmental
impacts
Boron can be toxic to vegetation and to wildlife at certain water concentrations and dietary
levels. Toxicity in fish can occur at levels of 10 to 300 milligrams per liter (mg/L) and mallard
duckling growth can be impacted at dietary levels of 30 to 300 mg/kg. Boron does not
magnify through the food chain but does accumulate in aquatic and terrestrial plants (WHO,
1998).
In animals, acute excessive amounts of boron can cause lethargy, rapid respiration, eye
inflammation, and dermal impacts (U.S. EPA, 2008a).
In humans, exposure via ingestion of large quantities over a short time period can adversely
impact the stomach, intestines, liver, kidney, and brain. Human exposure to high
concentrations of boron (85 mg/kg) can cause nausea, vomiting, diarrhea, and redness of the
skin (ATSDR, 2010a; U.S. EPA, 2008a).
A-2
-------
Appendix A —Adverse Impacts from Exposure to Metals and Toxic and Bioaccumulative Pollutants
Table A-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of Metals and Toxic and
Bioaccumulative Pollutants
Polliiliinl
liciichiiiiii'k Value''
Iieuehm;irk Value
I'lmlpoinl''
Poleulial A(l\erse 1 illp;icls
Cadmium
MRL for intermediate
oral exposure is 0.0005
mg/kg/day.
Musculoskeletal
impacts
Cadmium can readily bioaccumulate in aquatic organisms, especially mollusks, soil
invertebrates, and microorganisms. Cadmium contamination can lead to skeletal
malformations in fish (WHO, 1992).
Cadmium is a probable human carcinogen. Human exposure to high concentrations of
cadmium in drinking water and food can irritate the stomach, leading to vomiting and
diarrhea, and sometimes death. Chronic oral exposure via diet or drinking water to lower
concentrations can lead to kidney damage and weakened bones (ATSDR, 2008b; ATSDR,
2012a).
MRL for chronic oral
exposure is 0.0001
mg/kg/day.
Renal impacts
Chromium
(III)
MRL for intermediate
inhalation exposure
(soluble particulates) is
0.0001 milligrams per
cubic meter (mg/m3).
Respiratory impacts
The toxicity of chromium (III) to aquatic organisms is impacted by water hardness, being
more toxic in soft water (U.S. EPA, 1980a).
Fawad et al. (2016) studied chromium (III) accumulation in goldfish {Carassius auratus) and
found highest accumulation in the gills, followed by the intestines, and then the skin. When
chromium (III) levels exceed recommended limits, more of the metal accumulates in the fish
organs such as the liver, muscle, and gills and raises the mortality rate. Chromium can cause
physiological and behavioral changes (e.g., loss of appetite and reduced growth) (Fawad et al.,
2016).
Potential risks to humans from chromium exposure include respiratory and immunological
damage (ATSDR, 2012b).
Copper
MRL for acute and
intermediate oral
exposure is 0.01
mg/kg/day.
Gastrointestinal
impacts
Copper can be lethal to freshwater fish at concentrations ranging from 10 ppb - 20 ppb in soft
water (in hard water, the cations reduce the bioavailability of the dissolved copper). Adverse
impacts to fish include impaired neurological function, reduced reproduction, and damage to
gills, olfactory receptors, and lateral line cilia. Other freshwater aquatic organism impacts
include inhibiting photosynthesis of algae, reduced growth and reproduction of zooplankton
(due to impacts to algae food supply), and impaired growth and survival of mussels (Woody
and O'Neal, 2012).
Human exposure to high concentrations of copper can cause gastrointestinal distress (i.e.,
nausea, vomiting, and/or abdominal pain), liver and kidney damage, anemia, immunotoxicity,
and developmental toxicity (U.S. EPA, 1980b).
A-3
-------
Appendix A —Adverse Impacts from Exposure to Metals and Toxic and Bioaccumulative Pollutants
Table A-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of Metals and Toxic and
Bioaccumulative Pollutants
Polliiliinl
liciichiiiiii'k Value''
lieuehm;irk Value
I'lmlpoinl''
Poleulial A(l\erse 1 illp;icls
Iron
No MRL
Iron contamination can cause sublethal impacts to aquatic organisms, including reduced
growth, reduced development, and reduced reproduction. Iron also increases turbidity, reduces
primary production, and reduces interstitial spaces in benthic sediment, which can smother
invertebrates, periphyton, and eggs. Iron precipitates can clog and damage the gills of fish
resulting in respiratory impacts (Cadmus et al., 2018).
In humans, individuals with iron overload disorders can experience oxidative damage and
organ dysfunction, impacting metabolism (i.e., diabetes mellitus), the liver (i.e., cirrhosis), the
heart (i.e., cardiomyopathy), and endocrine glands (Dev andBabitt, 2017).
Lead
No MRL
Lead contamination can delay embryonic development, suppress reproduction, and inhibit
growth in fish, crab, and several other aquatic organisms (U.S. EPA, 1984; U.S. EPA, 2011a).
Human exposure to high concentrations of lead in drinking water (and other exposure
pathways) can result in adverse impacts to almost every organ and body system. Lead impacts
include neurological effects, with long-term exposure resulting in children (e.g., decreased
cognitive function, IQ loss, altered behavior and mood, and weakness in fingers, wrists, or
ankles), renal damage and reduced renal function, cardiovascular impacts (e.g., increased
blood pressure), reproductive impacts, and developmental impacts. Developmental impacts
include premature births and decreased child growth (ATSDR, 2019b).
Magnesium
No MRL
Magnesium generally does not pose a risk to aquatic life unless associated with other anions,
such as chloride or sulfate. Such compounds can contribute to salinity stress and impact
species diversity in sensitive aquatic communities (NHDES, 2019).
In humans, increased intake of magnesium salts may cause a change in bowel habits
(diarrhea). Drinking water in which both magnesium and sulfate concentrations are present in
high concentrations (approximately 250 mg/L each) can have a laxative effect (Sengupta,
2013).
A-4
-------
Appendix A —Adverse Impacts from Exposure to Metals and Toxic and Bioaccumulative Pollutants
Table A-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of Metals and Toxic and
Bioaccumulative Pollutants
Polliiliinl
liciichiiiiii'k Value''
Iieuehm;irk Value
I'lmlpoinl''
Poleulial A(l\erse 1 illp;icls
Manganese
MRL for chronic
inhalation exposure is
0.03 micrograms per
cubic meter (|ig/m3).
Neurological impacts
Manganese primarily accumulates in organisms lower in the food chain, such as
phytoplankton, algae, mollusks, and some fish (ATSDR, 2008c).
Although high levels can be toxic to humans, manganese is not generally considered toxic
when ingested (WHO, 2011). The most common impacts due to human exposure to high
concentrations of manganese involve the nervous system (ATSDR, 2008c).
Mercury 0
MRL for chronic oral
exposure to
methylmercury is 0.0003
mg/kg/day.
Developmental
impacts
Once in the environment, mercury can convert into methylmercury, increasing the potential
for bioaccumulation. Methylmercury contamination can reduce growth and reproductive
success in fish and invertebrates. Adverse impacts on wildlife include behavioral and
reproductive effects (Evers et al., 2011).
In humans, high exposure to inorganic mercury may result in damage to the gastrointestinal
tract, the nervous system, and the kidneys. Exposure at levels above the drinking water
maximum contaminant level (MCL), 0.002 mg/L, can result in kidney damage (U.S. EPA,
2019d). Fetuses, infants, and children are particularly susceptible to impaired neurological
development from methylmercury exposure (ATSDR, 1999; Evers et al., 2011).
Nickel
MRL for intermediate
inhalation exposure is
0.0002 mg/m3.
Respiratory impacts
Nickel can inhibit the growth of microorganisms (i.e., bacteria and protozoans) and algae.
Nickel toxicity in fish and aquatic invertebrates varies among species and can reduce fish
growth and adversely impact the immune system, muscles, gills, and liver. Nickel does not
biomagnify in the aquatic food web (ATSDR, 2005a; Eisler, 1998; Min et al., 2015; U.S.
EPA, 1986).
Human exposure via drinking water at high concentrations of nickel (e.g., 250 parts per
million (ppm)), can cause gastrointestinal effects (stomachache) and adverse effects to the
blood and kidney (ATSDR, 2005a).
MRL for intermediate
inhalation exposure is
0.00009 mg/m3.
Respiratory impacts
A-5
-------
Appendix A —Adverse Impacts from Exposure to Metals and Toxic and Bioaccumulative Pollutants
Table A-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of Metals and Toxic and
Bioaccumulative Pollutants
Polliiliinl
liciichiiiiii'k Value''
Iieuehm;irk Value
I'lmlpoinl''
Poleulial A(l\erse 1 illp;icls
Selenium
MRL for chronic oral
exposure is 0.005
mg/kg/day.
Dermal impacts
Selenium readily bioaccumulates. The bioaccumulation of selenium is of particular concern
due to its potential to impact higher trophic levels through biomagnification (Coughlan and
Velte, 1989). Elevated concentrations have caused fish kills and numerous sublethal effects
(e.g., organ damage, decreased growth rates, reproductive failure) to aquatic and terrestrial
organisms (NPS, 1997).
In humans, acute exposure via food or water adversely impacts the liver, respiratory system
(i.e., pulmonary edema and lesions of the lung), cardiovascular system (e.g., tachycardia),
gastrointestinal system (nausea, vomiting, et. al.), and neurological system (e.g., aches,
irritability, chills, and tremors). Chronic exposure via food or water can cause skin and tooth
discoloration, loss of hair and nails, excess tooth decay, and neurological impacts (i.e., lack of
mental alertness and listlessness) (U.S. EPA, 2000b, 2016b, and 2016c).
Thallium
Reference dose for
chronic oral exposure
(thallium chloride): 1.00
x 10"5 mg/kg/day (U.S.
EPA, 2010a).
Hair follicle atrophy
(U.S. EPA, 2010a)
Thallium can bioaccumulate in fish and vegetation in fresh and marine waters, as well as in
marine invertebrates, which suggests that thallium may be a potential risk to higher order
organisms invulnerable ecosystems (U.S. EPA, 2011b).
In humans, short-term exposure to thallium can lead to neurological symptoms (e.g.,
weakness, sleep disorders, muscular problems), alopecia, gastrointestinal effects, and
reproductive and developmental damage. Long-term exposures at levels above the MCL
(0.002 mg/L) change blood chemistry and damage liver, kidney, and intestinal and testicular
tissues (U.S. EPA, 2009a; U.S. EPA, 2009b).
Vanadium
MRL for intermediate
oral exposure is 0.01
mg/kg/day.
Hematological impacts
Vanadium contamination can increase blood pressure, decrease blood cell count, and cause
mild neurological effects in animals (ATSDR, 2012c).
There are very few reported cases of oral exposure to vanadium in humans; however, a few
reported incidences documented nausea, diarrhea, and stomach cramps (ATSDR, 2012c).
A-6
-------
Appendix A —Adverse Impacts from Exposure to Metals and Toxic and Bioaccumulative Pollutants
Table A-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of Metals and Toxic and
Bioaccumulative Pollutants
Polliiliinl
liciichiiiiii'k Value''
Iieuehm;irk Value
I'lmlpoinl''
Poleulial A(l\erse 1 illp;icls
Zinc
MRL for intermediate
and chronic oral
exposure is 0.3
mg/kg/day.
Hematological impacts
Elevated zinc levels adversely impact aquatic plant and animal growth, survival, and
reproduction. At higher concentrations, zinc is lethal to aquatic organisms by causing
irreversible destruction of the gill epithelium. Zinc contamination changes behavior, reduces
oxygen supply, interferes with gill uptake of calcium, and impairs reproduction in fish. High
zinc levels in birds can cause mortality, reduce growth, or damage the pancreas (CCME, 2018;
U.S. EPA Region 5, 2016).
In humans, short-term exposure to levels 10-15 times the recommended daily allowance (11
mg/day for men and 8 mg/day for women) can cause nausea, vomiting, and stomach cramps.
Long-term exposure at high levels can cause anemia and damage the pancreas (ATSDR,
2005b).
Acronyms: mg/day (milligrams per day); mg/kg (milligrams per kilograms); mg/kg/day (milligram per kilogram-day); mg/L (milligrams per liter); milligrams
per cubic meter (mg/m3); MRL (minimal risk level); ppb (parts per billion); ppm (parts per million),
a - Reference is ATSDR, 2019a unless otherwise listed.
b - The EPA based its quantitative human health assessments on the estimated concentration of inorganic arsenic in fish tissue (see Section 4).
c - The EPA based its quantitative wildlife and human health assessments on the estimated concentration of methylmercury in fish tissue (see Section 4).
A-7
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Appendix B —Adverse Impacts from Exposure to Total Dissolved Solids
APPENDIX B
ADVERSE IMPACTS FROM EXPOSURE TO TOTAL
DISSOLVED SOLIDS
Table B-l presents example adverse impacts from exposure to elevated concentrations of total
dissolved solids (TDS), which is present in discharges of the evaluated wastestreams (flue gas
desulfurization (FGD) wastewater and bottom ash transport water) from coal-fired power plants.
The table is not an exhaustive list of adverse impacts but provides context for an assessment of
environmental and ecological impacts from exposure to TDS and the corresponding increase in
salinity of the receiving water.
B-l
-------
Appendix B —Adverse Impacts from Exposure to Total Dissolved Solids
Table B-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of TDS
Aquatic Organism
TDS Concentration
Adverse Impacts
Literature Details
Source
Invertebrates
Salinity. >8.2 ppt
Oxygen consumption decreases
significantly among invertebrates
due to physiological stress.
Silva and Davies,
1999 (as cited in
Canedo-Argiielles et
al., 2013)
Ephemeroptera
(mayfly), Plecoptera
(stonefly), and
Pulmonate (molluscs)
Salinity: >3 mS/cm
(milliSiemens per
centimeter)
Salinity at which the organisms are
rarely registered. 48- and 72-hour
LC50 is approximately 5 to 20
mS/cm.
48- and 72-hour exposure.
Williams et al., 2003;
Hassell et al., 2006;
Echols et al., 2010;
Kefford et al., 2012
(as cited in Canedo-
Argiielles et al.,
2013)
Chironomids
(Chironomus tentans)
Chironomids exhibited toxic
effects at >1,100 mg/L.
Researchers synthesized Red Dog
Mine effluent and exposed larval
chironomids to a TDS concentration
of 2,089 mg/L. Their dry weight (a
growth indicator for these
organisms) was reduced by 45
percent. The researchers also
observed reduced survival among
larval chironomids exposed to
synthetic Kensington Mine effluent
at TDS concentrations of 1,750 and
2,240 mg/L.
Researchers maintained larval
chironomids in test containers and
exposed them to synthetic effluent
(based on discharge from one of two
local mines in Alaska) for 10 days.
They measured mortality and dry
weight at the end of the incubation.
Chapman et al., 2000
Coontail
(Ceratophyllus
demersum) and
cattail (Typha sp.)
l,170mg/L (Estimated)
In a 1988 study of plant
communities near irrigation drains
in Stillwater Marsh, researchers
found that coontails and cattails
growing in the marsh had nearly
been eliminated. TDS
concentrations were modeled to
have increased from 270 mg/L
(historical values from 1845 to
1860) to 1,170 mg/L (projected
values for 1992 and beyond, as
estimated in 1988).
Reported TDS concentration data at the
wetland inlet flow at Stillwater Marsh,
Nevada, were estimated for 1992 and
beyond. Reductions in coontail and
cattail in Stillwater Marsh were based
on comparisons of observed
populations in 1988 to populations
recorded in a 1959 survey by the U.S.
Fish and Wildlife Service.
Hallock and Hallock,
1993
B-2
-------
Appendix B —Adverse Impacts from Exposure to Total Dissolved Solids
Table B-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of TDS
Aquatic Organism
TDS Concentration
Adverse Impacts
Literature Details
Source
Vascular aquatic
plants, fish
20,000 mg/L
After Carson Sink was inundated
and TDS concentrations rose to
20,000 mg/L, vascular aquatic
plants died. Fish did well initially,
but they started dying after about a
year when water evaporated and the
TDS concentration increased.
Historical TDS concentrations in
Carson Sink, Nevada, likely varied
dramatically based on inundation. The
plant species that were reported to be
present in a 1929 survey could
withstand TDS concentrations between
650 and 16,800 mg/L during normal
conditions. TDS concentrations when
the wetland is filled have been recorded
at 3,100 mg/L (1983) and 20,000 mg/L
(1987).
Hallock and Hallock,
1993
American coot
(Fulica americana)
1,170 mg/L (Estimated)
Coots had reduced field nest
success and low fecundity due to
vegetation loss and subsequent nest
exposure. Nesting success
decreased from 43 to 52 percent
(1968 to 1970) to 25 percent (1988).
The researchers attributed
vegetation loss to drought,
increased TDS, and increased
predation.
Nesting success for the study was
measured during an annual assessment
in May 1988. Those values were
compared to nesting surveys conducted
in the Stillwater Wildlife Management
Area in 1968-1970, 1983, and 1987-
1988.
Hallock and Hallock,
1993
Atlantic salmon
(,Salmo salar),
rainbow trout (Salmo
gairdneri), and brook
trout (Salvelinus
fontinalis)
>522 mg/L calcium sulfate
(CaSO/i) Calcium in the
experimental water ranged
between 34-544 mg/L.
Researchers found low survival
rates (~33 percent) when eggs were
incubated in very hard water with
calcium sulfate concentrations >522
mg/L during water hardening (the
process by which the shells of
newly shed eggs absorb water and
become firm over the course of a
few hours). High concentrations of
chloride, sulfate, and sodium ions
did not affect egg survival.
Eggs were incubated to eye-up (the
point at which eyes develop on the
embryo). Eggs were exposed to
treatment water for 1.5 or 3.5 hours of
hardening, depending on the
experiment. Egg survival rates were not
significantly affected by water
chemistry after hardening.
Ketolaetal., 1988
B-3
-------
Appendix B —Adverse Impacts from Exposure to Total Dissolved Solids
Table B-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of TDS
Aquatic Organism
TDS Concentration
Adverse Impacts
Literature Details
Source
Fish communities
2,000 - 2,300 mg/L
Researchers documented notably
lower species richness and density
at two sampling locations
immediately downstream of the
coal mining wastewater discharges.
Fish community metrics declined
notably at three sampling stations
among 17 stations compared to the
reference station. However, one of
these three sites may have been
impacted by factors other than TDS
concentrations (i.e., toxicity from
untreated coal plant runoff and
sewage). Based on TDS data
collected at all sampling sites,
researchers identified 2,000 to
2,300 mg/L as the limit before fish
communities experience adverse
effects.
Researchers sampled fish populations
and measured water quality parameters
at 17 locations along the South Fork of
Tenmile Creek in southwestern
Pennsylvania during the summers of
2007 and 2008. Researchers collected
10,940 fish representing seven families
and 42 species/hybrids during the
survey.
Kimmel and Argent,
2010
Walleye (Stizostdion
vitreum), northern
pike (Esox lucius),
yellow perch (Perca
jlavescens), white
sucker (Catostomus
commersoni), and
common carp
(Cyprinus carpio)
1,750-6,700 mg/L
(Concentrations at which
eggs were incubated)
>2,400 mg/L
(Concentration at which
adverse impacts were
observed)
Fish egg hatching success
significantly decreased at TDS
concentrations above 2,400 mg/L
for all species studied except
common carp. Embryo survival
decreased at TDS concentrations
above 2,400 mg/L for walleye and
northern pike. Survival to hatching
was less than 2 percent for all
species except common carp at TDS
concentrations above 2,400 mg/L.
Researchers collected fish eggs during
spawning runs between mid-April and
May 1992 in Devils Lake, North
Dakota, and Many Point Lake,
Minnesota. They incubated the
fertilized eggs overnight, and assessed
fertilization success after one or three
days, depending on species. Live
embryos were incubated and counted
every one to three days until hatching.
Koel and Peterka,
1995
B-4
-------
Appendix B —Adverse Impacts from Exposure to Total Dissolved Solids
Table B-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of TDS
Aquatic Organism
TDS Concentration
Adverse Impacts
Literature Details
Source
Water flea
{Ceriodaphnia dubid)
Variable ion concentrations:
Na = 15,000 mg/L,
K = 450 mg/L,
Ca =1,800 mg/L,
Mg = 320 mg/L,
CI = 26,000 mg/L
(highest reported
concentration)
Concentrations for the four (of six
total) samples that were acutely
toxic to C. dubia.
Grab samples were collected from the
Black Warrior Basin, Alabama.
Twenty-four- and 48-hour survival for
two species of water flea (C. dubia and
Daphnia magna) and flathead minnows
{Pimephales promelas) were
ascertained. Within 36 hours of
collection, all samples were tested for
acute toxicity. Exposure began with the
organisms that were less than 24 hours
old and lasted 48 hours.
Mount etal., 1993
Daphnids {Daphnia
magna)
Elevated concentration of
major ions (conductivity up
to 30,300 |iS/cm). Variable
ion concentration in
leachate:
Na = 7,700 mg/L,
K = 270 mg/L,
Ca = 379 mg/L,
Mg = 758 mg/L,
CI = 11,200 mg/L (Highest
reported concentration)
Concentrations for two (of the five
total) samples showed acute toxicity
to D. magna.
Water samples were taken from
irrigation drain waters from the
Stillwater Wildlife Management Area
in southwestern Nevada. 24-and 48-
hour survival for two species of water
flea (C. dubia and Daphnia magna)
and flathead minnows (Pimephales
promelas). Acute toxicity tests with
Daphnia magna were conducted on
both ambient samples as well as
reconstituted waters.
Mount etal., 1993
Daphnids
(iCeriodaphnia dubia
and Daphnia magna),
fathead minnows
(Pimephales
promelas)
10,000 mg/L a
No clear information on adverse
impacts were provided. However,
marginal plots of the regression
equations from the ion toxicity
model showed that C. dubia are, in
general, the most sensitive of the
three species to major ion toxicity,
while fathead minnows are the least
sensitive.
All organisms were obtained from in-
house culture. Daphnids were less than
24 hours old at test initiation while
fathead minnows were 1 to 7 days old.
Researchers followed general EPA
guideline for conducting acute whole
effluent toxicity tests. Exposure periods
were 48 hours for C. dubia and D.
magna and 96 hours for fathead
minnows, with daily observations of
mortality. Tests were conducted under
a 16-hour:8-hourlight:dark
photoperiod.
Mount etal., 1997
B-5
-------
Appendix B —Adverse Impacts from Exposure to Total Dissolved Solids
Table B-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of TDS
Aquatic Organism
TDS Concentration
Adverse Impacts
Literature Details
Source
Coho salmon
{Oncorhynchus
kisutch)
>1,250 ppm
Coho salmon eggs from two
broodyears experienced decreased
fertilization success when exposed
to high TDS concentrations. For
both broodyears, fertilization
success decreased as the TDS
concentration during fertilization
increased. For one broodyear, eggs
experienced higher mortality
between eye-up and the alevin stage
when maintained at high TDS
concentrations after fertilization.
Adverse impacts were observed
beginning at TDS concentrations of
1,250 ppm.
Researchers incubated fertilized coho
salmon embryos from broodyears 1999
and 2000 for 96 hours.
Stekoll et al., 2003
Coho salmon
(iOncorhynchus
kisutch), chum
salmon (0. keta),
king salmon (0.
tschawytscha), pink
salmon (0.
gorbuscha),
steelhead salmon (0.
mykiss), and arctic
char (Salvelinus
alpinus)
For the continuous exposure
study: LOEC: 750 ppm for
chum and steelhead salmon.
LOEC: 250 ppm for king,
pink, and coho salmon.
LOEC: 1875 ppm for arctic
char.
For the fertilization
exposure study, every
species had a different
LOEC ranging from 250 to
1875 ppm.
The number of unfertilized eggs
increased with TDS concentrations
for all species except arctic char.
The most sensitive species (coho
salmon) exhibited adverse effects at
TDS concentrations of 250 ppm.
Steelhead salmon were the only
species that exhibited a significant
effect in the post-fertilization
exposure experiment, with a
reported LOEC of 1875 ppm.
Researchers incubated fertilized eggs to
the 4- or 8-cell stage, which lasted from
18 to 43 hours. These bioassays were
conducted for broodyears 2000 and
2001.
TDS concentrations in the test solution
ranged from 0 to 2,500 ppm.
Stekoll et al., 2003
B-6
-------
Appendix B —Adverse Impacts from Exposure to Total Dissolved Solids
Table B-l. Examples of Adverse Impacts from Exposure to Elevated Concentrations of TDS
Aquatic Organism
TDS Concentration
Adverse Impacts
Literature Details
Source
Coho salmon
(Oncorhynchus
kisutch)
>2,500 ppm
No consistent adverse impacts
related to TDS were documented at
the TDS concentrations tested.
Researchers exposed coho salmon
eggs to differing chronic TDS
concentrations as they developed.
Higher TDS concentrations during
fertilization were found to result in
higher pre-hatch mortality, and
higher TDS concentrations at
hatching were related to higher
post-hatch mortality. Fish exposed
to higher TDS concentrations
generally had shorter lengths and
lower weights at button-up (stage at
which fish have no visible yolk
sac).
Researchers incubated the fish eggs for
at least six months.
TDS ranged from 125 to 2,500 ppm in
test solutions.
Stekoll et al., 2003
Acronyms: Ca (calcium); CI (chlorine); K (potassium); LC50 (lethal concentration required to kill 50 percent of the population); LOEC (lowest observed effects
concentration); Mg (magnesium); mg/L (milligrams per liter); mS/cm (milliSiemens per centimeter); |iS/cm (microSiemens per centimeter); Na (sodium); ppm
(parts per million); ppt (parts per thousand); TDS (total dissolved solids).
a - The test solutions were prepared in a lab by dissolving individual 10,000 mg/L of ion salts with moderately hard reconstituted water (MHRW). For tests
evaluating only one salt (one cation and one anion), test solutions were prepared by serially diluting the 10,000-mg/L stock solutions with MHRW to develop a
series of test concentrations.
B-7
-------
Appendix C— Water Quality Module Methodology
APPENDIX C
WATER QUALITY MODULE METHODOLOGY
This appendix presents the model equations, input variables and constants, pollutant benchmark
values, and methodology limitations/assumptions for the Water Quality Module of the
Immediate Receiving Water (IRW) Model. This supplemental environmental assessment
(Supplemental EA) analyzes only the proposed changes to the 2015 rule regarding best available
technology economically achievable (BAT) effluent limitations and pretreatment standards for
existing sources (PSES) for the evaluated wastestreams—specifically, flue gas desulfurization
(FGD) wastewater and bottom ash transport water.
The Water Quality Module equations are organized by the methodology for nonvolatile
pollutants (arsenic, cadmium, copper, lead, nickel, selenium, thallium, and zinc) and volatile
pollutants (mercury). The EPA used the equations to calculate total and dissolved pollutant
concentrations in receiving waters and total pollutant concentrations in sediment within the
immediate discharge zone. The following tables describe the input requirements and data sources
used in the Water Quality Module:
• Table C-l. Input Variables with Values from Site-Specific Data Sources.
• Table C-2. Input Variables and Constants with Globally Assigned Values.
• Table C-3. Input Variables with Values from Regional Data Sources.
• Table C-4. Partition Coefficients.
• Table C-5. Total Suspended Solids (TSS) Concentrations in Surface Waters.
• Table C-6. Regional Surface Water Temperatures.
• Table C-l. National Recommended Water Quality Criteria (NRWQC) and Drinking
Water Maximum Contaminant Levels (MCLs).
The EPA calculated effluent pollutant loadings associated with the discharge of the evaluated
wastestreams as part of its engineering analysis—see the Supplemental Technical Development
Document for Proposed Revisions to the Effluent Limitations Guidelines and Standards for the
Steam Electric Power Generating Point Source Category (Supplemental TDD), Document No.
EPA-821-R-19-009 (U.S. EPA, 2019a). The Water Quality Module performs calculations on a
per-immediate-receiving-water basis. For coal-fired power plants that discharge to multiple
receiving waters, the EPA divided the plant-specific pollutant loadings accordingly among the
receiving waters based on water diagrams provided in response to the Questionnaire for the
Steam Electric Power Generating Effluent Guidelines (Steam Electric Survey) (U.S. EPA,
2010c). The EPA used the IRW Model to evaluate the environmental impacts from 105 coal-
fired power plants in the receiving water quantitative analysis (106 unique immediate receiving
waters).
While the Water Quality Module is not designed to account for pollutant speciation, the EPA did
include assumptions of pollutant speciation for arsenic and mercury as appropriate in the
subsequent Wildlife and Human Health Modules (see Appendix D and Appendix E,
C-l
-------
Appendix C— Water Quality Module Methodology
respectively). The EPA used total selenium loadings in the Water Quality Module; however, due
to the partition coefficients available, the EPA assumed the dominant form of selenium in the
receiving water was selenate (i.e., selenium (VI)). The EPA selected the selenate partition
coefficient because, per the Steam Electric Survey, the significant majority of coal-fired power
plants (113 of 150, or 75 percent) operating wet FGD systems use forced oxidation systems (U.S.
EPA, 2010c). According to Maher et al. (2010), the majority of selenium discharged from these
types of scrubbers is in the form of selenate.
Methodology Updates Subsequent to the 2015 Final EA
Since the completion of the 2015 Final EA, the EPA incorporated the following updates to the
equations, data sets, and parameter values used in the Water Quality Module:
• NHDPlus Version 2. The EPA used the most recent version of the National
Hydrography Dataset Plus (NHDPlus). NHDPlus Version 2 has been updated by its
developers to incorporate higher resolution data sets and revised watershed
boundaries and elevation data, among other improvements.
• Lake depth. For the 2015 Final EA, the EPA obtained site-specific mean and
maximum lake depth values by researching external sources. NHDPlus Version 2
now includes modeled estimates of mean lake depth. For the Supplemental EA, the
EPA continued to use the site-specific mean depth values used in the 2015 Final EA,
where available. However, for those receiving waters where the EPA had previously
identified only a maximum lake depth value (instead of the mean depth, which is
preferred), the EPA used the modeled mean depth values provided by the Lake
Morphometry layer in NHDPlus Version 2.
• Lake surface area. For the 2015 Final EA, the EPA obtained site-specific lake
surface area values by researching external sources. The Lake Morphometry layer in
NHDPlus Version 2 now includes surface area data. For the Supplemental EA, the
EPA used surface area data from the Lake Morphometry layer, where available;
otherwise, the EPA used external sources for surface area.
• Average annual streamflow. For the 2015 Final EA, the EPA selected the average
annual streamflow data calculated using the Vogel method in NHDPlus. For the
Supplemental EA, the EPA used the updated flow values in NHDPlus Version 2 that
were calculated using the Extended Unit Runoff Method (EROM). The EPA
determined that EROM was a more up-to-date and robust method for calculating
streamflow than the Vogel method due to its use of more recent data in its
calculations and availability of estimated monthly flow rates in addition to average
annual flow rates.
• Freshwater NRWQC. The EPA incorporated the updated NRWQCs for cadmium and
selenium.
Cadmium. The EPA has updated the acute and chronic NRWQCs to match
updates finalized in 2016.
- Selenium. The EPA has updated the acute and chronic NRWQCs to reflect
updates finalized in 2016. Selenium acute and chronic NRWQCs were changed to
include discrete values for lotic and lentic systems. This was intended to reflect
C-2
-------
Appendix C— Water Quality Module Methodology
differences in selenium bioaccumulation documented in lotic and lentic
environments.
IRW Model: Water Quality Module Equations
The EPA calculated the nonvolatile pollutant concentrations for the following compartments
within the receiving water:
• Total pollutant concentration in water column (Cwc).
• Dissolved pollutant concentration in water column (Cdw).
• Total pollutant concentration in sediment (Cbs).
The EPA used the equations presented below to calculate receiving water concentrations for
arsenic, cadmium, copper, lead, mercury, nickel, selenium, thallium, and zinc.
Equation C-l
„ _ Lt0tai
wT°t'Rivers ~ ?o +0 1 / f , + K ,/ V ¦
^Vr„n| V ¦ ) xwater AN-wt v river
cuui river
Where:
CWTot,Rivers
t otal pollutant concentration in the
waterbody (water and sediment) in rivers
and streams from pollutant loading (grams
per cubic meter (g/m3) or milligrams per
liter (mg/L))
Output from Equation C-l
Ltotal
Average pollutant loading from evaluated
wastestreams (grams per day (g/day))
Site-specific value from
engineering analysis, based
on annual average
(see Table C-l)
Qcool
Total cooling water effluent flow (cubic
meters per day (m3/day))
Site-specific value from
engineering analysis
(see Table C-l)
Qriver
Receiving water average annual flow
(m3/day)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
fwater
=
Fraction of total waterbody pollutant
concentration 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
and streams (m3)
Output from Equation C-l 1
C-3
-------
Appendix C— Water Quality Module Methodology
Equation C-2
„ _ Lt0tai
WTOt' Lake _ (Qcool + Q^Jxfwater + KwtXV^
Where:
CWTot, Lake
t otal pollutant concentration in the
waterbody (water and sediment) in lakes,
ponds, and reservoirs from pollutant loading
(g/m3 or mg/L)
Output from Equation C-2
Ltotal
Average pollutant loading from evaluated
wastestreams (g/day)
Site-specific value from
engineering analysis, based
on annual average
(see Table C-l)
Qcool
Total cooling water effluent flow (m3/day)
Site-specific value from
engineering analysis
(see Table C-l)
Qlake
Average annual flow exiting the lake, pond,
or reservoir (rnVday)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
fwater
=
Fraction of total waterbody pollutant
concentration 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 for lakes,
ponds, and reservoirs (m3)
Output from Equation C-l2
Equation C-3
Where:
Cwc
=
Total pollutant concentration in water column
(mg/L)
Output from Equation C-3
fwater
=
Fraction of total waterbody pollutant
concentration in water column (unitless)
Output from Equation C-6
CWTot
(Rivers or
Lakes)
Total pollutant concentration in the waterbody
(water and sediment) from pollutant loading
(g/m3 or mg/L)
Output from Equation C-l
or Equation C-2
dz
— "P x x
^\\c 1 water ^wtot (Rivers or Lakes) i
Qw
C-4
-------
Appendix C— Water Quality Module Methodology
dz
(Rivers or
Lakes)
Depth of the waterbody (meters (m))
River or stream: output
from Equation C-9
Lake, pond, or reservoir:
site-specific value (see
Table C-l)
dw
(Rivers or
Lakes)
Depth of water column (m)
River or stream: output
from Equation C-l
Lake, pond, or reservoir:
site-specific value (see
Table C-l)
Equation C-4
Cdw " Cwc (l +Kdsw x TSS x 0.000001
Where:
Cdw
=
Dissolved pollutant concentration in water
(mg/L)
Output from Equation C-4
Cwc
=
Total pollutant concentration in water column
(mg/L)
Output from Equation C-3
Kdsw
Suspended sediment-surface water partition
coefficient (milliliters per gram (mL/g))
Globally assigned value
(see Table C-2 and Table
C-4)
TSS
Total suspended solids (mg/L)
Regionally assigned value
(see Table C-3 and Table
C-5)
0.000001
=
Conversion factor (L/mL)(g/mg)
Conversion factor
Equation C-5
Where:
Cbs
=
Total pollutant concentration in sediment
(mg/L)
Output from Equation C-5
fBenth
Fraction of total waterbody pollutant
concentration in benthic sediment (unitless)
Output from Equation C-l5
dz
Cbs — ^Beiitti X (Rivers or Lakes) X j-
Oh
C-5
-------
Appendix C— Water Quality Module Methodology
CWTot
(Rivers or
Lakes)
Total pollutant concentration in the waterbody
(water and sediment) from pollutant loading
(g/m3 or mg/L)
Output from Equation C-l
or Equation C-2
dz
(Rivers or
Lakes)
Depth of the waterbody (m)
River or stream: output
from Equation C-9
Lake, pond, or reservoir:
site-specific value (see
Table C-l)
db
(Rivers or
Lakes)
Depth of upper benthic sediment layer (m)
Globally assigned value of
0.03 m (see Table C-2)
Equation C-6
[1 + (Kdsw x TSS x 0.000001)] x ^
1 water
[1 + (Kdsw x TSS x 0.000001)] x ^ + (bsp + Kdbs x bsd) x ^
Where:
fwater
Fraction of total waterbody pollutant
concentration in water column
(unitless)
Output from Equation C-6
KdSw
=
Suspended sediment-surface water
partition coefficient (mL/g)
Globally assigned value
(see Table C-2 and Table C-4)
TSS
=
Total suspended solids (mg/L)
Regionally assigned value
(see Table C-3 and Table C-5)
0.000001
=
Conversion factor (L/mL)(g/mg)
Conversion factor
dw
(Rivers or
=
Depth of water column (m)
River or stream: output from
Equation C-l
Lakes)
Lake, pond, or reservoir:
site-specific value (see Table C-l)
dz
(Rivers or
=
Depth of the waterbody (m)
River or stream: output from
Equation C-9
Lakes)
Lake, pond, or reservoir:
site-specific value (see Table C-l)
bsp
Bed sediment porosity (cubic
centimeter per cubic centimeter
(cm3/cm3))
Globally assigned value of 0.6
cm3/cm3 (see Table C-2)
C-6
-------
Appendix C— Water Quality Module Methodology
Kdbs
=
Bottom sediment-pore water partition
coefficient (mL/g)
Globally assigned value
(see Table C-2 and Table C-4)
bsd
Bed sediment bulk density (gram per
cubic centimeter (g/cm3)) or
(kilogram per liter (kg/L))
Globally assigned value of 1 g/cm3
(see Table C-2)
db
=
Depth of upper benthic layer (m)
Globally assigned value of 0.03 m
(see Table C-2)
Equation C-7
Q
A = ^nver
w V x Width
Where:
dw, river
=
Depth of water column (m)
Output from Equation C-7
Qriver
Receiving water average annual flow
(m3/s)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
V
Receiving water velocity (m/s)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
Width river
=
Receiving water width (m)
Output from Equation C-8
Equation C-8
Where:
Widthriver
=
Receiving water width (m)
Output from Equation C-8
Qriver
Receiving water average annual flow
(m3/s)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
Equation C-9
dz, river db dw, river
Where:
dz, river
=
Depth of the waterbody (m)
Output from Equation C-9
db
=
Depth of upper benthic sediment layer (m)
Globally assigned value 0.03
m (see Table C-2)
dw, river
=
Depth of water column (m)
Output from Equation C-7
Widthdver= 5.1867 x Q04559
11 u driver
C-7
-------
Appendix C— Water Quality Module Methodology
Equation C-10
K\vt — (fwater X ksw ) (fbenth X kSed) (fwaterX kVol) (fbenth X
Where:
Kwt
Water concentration dissipation rate
constant (1/day) for nonvolatile pollutants
(see Equation C-16 for volatile pollutants)
Output from Equation C-10
fwater
=
Fraction of total waterbody pollutant
concentration in water column (unitless)
Output from Equation C-6
ksw
=
Degradation rate for water column (1/day)
Globally assigned value of
0/day (see Table C-2)
fbenth
Fraction of total waterbody pollutant
concentration in benthic sediment
(unitless)
Output from Equation C-15
ksed
=
Degradation rate for sediment (1/day)
Globally assigned value of
0/day (see Table C-2)
kvol
Water column volatilization loss rate
constant (1/day)
Globally assigned value of
0/day (see Table C-2)
Kb
Benthic burial rate (1/day)
Output from Equation C-14
Equation C-ll
Vriver Wldthriver ^ Len ^ dz,river
Where:
Vriver
=
Flow independent mixing volume for
rivers and streams (m3)
Output from Equation C-ll
Widthriver
=
Receiving water width (m)
Output from Equation C-8
Len
Length of stream reach (m)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
dz, river
=
Depth of the waterbody (m)
Output from Equation C-9
C-8
-------
Appendix C— Water Quality Module Methodology
Equation C-12
Vlake — Area x dz,lake
Where:
Vlake
1 low independent mixing volume for
lakes, ponds, and reservoirs (m3)
Output from Equation C-12
Area
Surface area of the lake (m2)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
dz,lake
Depth of the lake (m)
Site-specific value from
NHDPlus Version 2 or other
data source (see Table C-l)
Equation C-13
1
=
d 1+Kdswx TSS x 0.000001
Where:
fd
=
Dissolved fraction in water (unitless)
Output from Equation C-13
Kdsw
=
Suspended sediment-surface water
partition coefficient (mL/g)
Globally assigned value
(see Table C-2 and Table C-4)
TSS
=
Total suspended solids (mg/L)
Regionally assigned value (see
Table C-3 and Table C-5)
0.000001
=
Conversion factor (L/mL)(g/mg)
Conversion factor
Equation C-14
WB
Kb — fbenth X —~j
ab
Where:
Kb
=
Benthic burial rate (1/day)
Output from Equation C-14
fbenth
Fraction of total waterbody pollutant
concentration in benthic sediment
(unitless)
Output from Equation C-l 5
WB
=
Rate of burial (m/day)
Globally assigned value of 0
m/day (see Table C-2)
db
=
Depth of upper benthic sediment layer (m)
Globally assigned value of
0.03 m (see Table C-2)
C-9
-------
Appendix C— Water Quality Module Methodology
Equation C-15
(bsp + Kdbs x bsd) x ^
^Benth "
[1 + (Kdsw x TSS x 0.000001)] x ^ + (bsp + Kdbs x bsd) x ^
Where:
fbenth
Fraction of total waterbody pollutant
concentration in benthic sediment
(unitless)
Output from Equation C-15
bsp
=
Bed sediment porosity (cm3/cm3)
Globally assigned value of 0.6
cm3/cm3 (see Table C-2)
Kdbs
=
Bottom sediment-pore water partition
coefficient (mL/g)
Globally assigned value
(see Table C-2 and Table C-4)
bsd
=
Bed sediment bulk density (g/cm3) or
(kg/L)
Globally assigned value of 1
g/cm3 (see Table C-2)
db
=
Depth of upper benthic sediment layer (m)
Globally assigned value of
0.03 m (see Table C-2)
dz
=
Depth of the waterbody (m)
Output from Equation C-9
Kdsw
=
Suspended sediment-surface water
partition coefficient (mL/g)
Globally assigned value
(see Table C-2 and Table C-4)
TSS
=
Total suspended solids (mg/L)
Regionally assigned value
(see Table C-3 and Table C-5)
0.000001
=
Conversion factor (L/mL)(g/mg)
Conversion factor
dw
(Rivers or
=
Depth of water column (m)
River or stream: output from
Equation C-7
Lakes)
Lake, pond, or reservoir:
site-specific value (see
Table C-l)
The EPA calculated the volatile pollutant concentrations in each of the three compartments
within the receiving water by building off the equations used to calculate nonvolatile pollutant
concentrations. The water concentration dissipation rate constant, Kwt, in Equation C-10 was
replaced with a Kwt,volatile factor (see Equation C-16) that takes into account volatilization loss
(kvoi). The EPA used the equations presented below in combination with the preceding equations
to calculate receiving water concentrations for mercury only.
C-10
-------
Appendix C— Water Quality Module Methodology
Equation C-16
K\vt, volatile — (fwater X ksw ) (fbenth X ksed) (fwater X fd X kVol) (fbenth X
Where:
Kwt, volatile
=
W ater concentration dissipation rate
constant (1/day)
Output from Equation C-16
fwater
=
Fraction of total waterbody pollutant
concentration in water column (unitless)
Output from Equation C-6
ksw
=
Degradation rate for water column (1/day)
Globally assigned value of
0/day (see Table C-2)
fbenth
Fraction of total waterbody pollutant
concentration in benthic sediment
(unitless)
Output from Equation C-15
ksed
=
Degradation rate for sediment (1/day)
Globally assigned value of
0/day (see Table C-2)
fd
=
Dissolved fraction in water (unitless)
Output from Equation C-13
kvoi
Water column volatilization loss rate
constant (1/day)
Output from Equation C-17
Kb
Benthic burial rate (1/day)
Output from Equation C-14
Equation C-17
Where:
kvoi
=
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
(Rivers or
Lakes)
Depth of water column (m)
River or stream: output from
Equation C-7
Lake, pond, or reservoir:
site-specific value (see Table
C-l)
k-voi
Kvxfd
C-ll
-------
Appendix C— Water Quality Module Methodology
Equation C-18
|(TW-Thic)
water
Where:
Kv
=
Diffusion transfer rate (m/day)
Output from Equation C-18
©water
=
Temperature correction (unitless)
Globally assigned value of
1.026 (see Table C-2)
Tw
Temperature of the waterbody (Kelvin
(K))
River or stream: regionally
assigned value
(see Table C-3 and Table C-6)
Lake, pond, or reservoir:
globally assigned value (see
Table C-3 and Table C-6)
Thic
=
Temperature of Henry's Law Constant
(HLC) (K)
Globally assigned value of 298
K (see Table C-2)
Kl
(Rivers or
Lakes)
Liquid-phase transfer coefficient (m/day)
River or stream: output from
Equation C-19
Lake, pond, or reservoir:
output from Equation C-21
Kg
(Rivers or
Lakes)
Gas-phase transfer coefficient (m/day)
River or stream: globally
assigned value of 100 m/day
(see Table C-2)
Lake, pond, or reservoir:
output from Equation C-23
HLC
Henry's Law Constant (atm-m3/mole) 1
Globally assigned value of
0.0113 atm-m3/mol (see Table
C-2)
R
Universal gas constant (atm-m3/K-mole)
Globally assigned value of
0.00008205 atm-m3/K-mole
(see Table C-2)
1 Units for Henry's Law Constant are atmospheres of absolute pressure (atm) per cubic meter (m3) per mole (mol).
C-12
-------
Appendix C— Water Quality Module Methodology
Equation C-19
I10"4 xDwxv
KL(Rivers)- J ~j ><86,400
Where:
KL(Rivers)
=
Liquid-phase transfer coefficient (m/day)
Output from Equation C-19
Dw
=
Diffusivity of the pollutant in water
(square centimeter per second (cm2/s))
Output from Equation C-20
V
=
Receiving water velocity (m/s)
Site-specific value from
NHDPlus Version 2
(see Table C-l)
dz,river
=
Depth of waterbody (m)
Output from Equation C-9
86,400
=
Conversion factor (s/day)
Conversion factor
Equation C-20
D =
22xl0"5
w mw2/3
Where:
Dw
=
Diffusivity of the pollutant in water
(cm2/s)
Output from Equation C-20
MW
Molecular weight (grams per mole
(g/mol))
Globally assigned value of
200.59 g/mol for mercury (see
Table C-2)
Equation C-21
Id /k033\
(Lakes) = X w10 x jx X ^Cw'6? X 86,400
Where:
KL(Lakes)
=
Liquid-phase transfer coefficient (m/day)
Output from Equation C-21
Cd
=
Drag coefficient (unitless)
Globally assigned value of
0.0011 (see Table C-2)
Wio
=
Wind velocity 10 meters above water
surface (m/s)
Regionally assigned value
(see Table C-3)
Pa
=
Density of air corresponding to water
temperature (g/cm3)
Globally assigned value of
0.0012 g/cm3 (see Table C-2)
C-13
-------
Appendix C— Water Quality Module Methodology
Pw
=
Density of water corresponding to water
temperature (g/cm3)
Globally assigned value of 1
g/cm3 (see Table C-2)
k
=
Von Karman's constant (unitless)
Globally assigned value of 0.4
(see Table C-2)
^2
=
Dimensionless viscous sublayer thickness
(unitless)
Globally assigned 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-22
Where:
Scw
=
Water Schmidt number (dimensionless)
Output from Equation C-22
|iw
=
Viscosity of water corresponding to water
temperature (g/cm-s)
Globally assigned value of
0.0169 g/cm-s (see Table C-2)
Pw
=
Density of water corresponding to water
temperature (g/cm3)
Globally assigned value of 1
g/cm3 (see Table C-2)
Dw
=
Diffusivity of the pollutant in water
(cm2/s)
Output from Equation C-20
Equation C-23
/k033\
Kg(Lakes) = VQ x W10 x f — J X Scf67 x 86,400
Where:
Kg(lakes)
=
Gas-phase transfer coefficient (m/day)
Output from Equation C-23
Cd
=
Drag coefficient (unitless)
Globally assigned value of
0.0011 (see Table C-2)
Wio
=
Wind velocity 10 meters above water
surface (m/s)
Regionally assigned value
(see Table C-3)
k
=
Von Karman's constant (unitless)
Globally assigned value of 0.4
(see Table C-2)
=
Dimensionless viscous sublayer thickness
(unitless)
Globally assigned 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
r w
SCw=P.-D»
C-14
-------
Appendix C— Water Quality Module Methodology
Equation C-24
(1.32 + 0.009Ta) x 105
Sc = —
a Y 9
MW2/3
Where:
SCa
=
Air Schmidt number (dimensionless)
Output from Equation C-24
Ta
=
Air temperature (K)
Regionally assigned value (see
Table C-3)
MW
Molecular weight (g/mol)
Globally assigned value of
200.59 g/mol for mercury (see
Table C-2)
The EPA calculated the potential water quality impacts to aquatic life and humans by comparing
the pollutant concentration in the water column (Cwc or Cdw, depending on the benchmark) to the
water quality benchmark values presented in Table C-7.
IRW Model: Water Quality Module Inputs
Table C-l. Input Variables with Values from Site-Specific Data Sources
Input Yiirhihk-
Input ( ;ik'iior\ ;nul
Description
Silo-Specific l);il;i Source
Ltotal
Plant-specific effluent
characteristic.
Total waterbody loading.
The EPA estimated the pollutant discharge loadings using the
methodology presented in the Supplemental TDD.
Qcool
Plant-specific effluent
characteristic.
Total cooling water effluent
flow by receiving water.
The EPA determined the estimated cooling water flow for
each plant by outfall based an assessment of industry survey
results using the methodology outlined in the memorandum
"Receiving Water Characteristics Analysis and Supporting
Documentation for the 2019 Steam Electric Supplemental
Environmental Assessment" (the Receiving Water
Characteristics memorandum) (ERG, 2019d).
Qriver
Receiving water characteristic
for rivers and streams.
Waterbody annual flow.
The EPA extracted average annual flow values from the
NHDPlus Version 2 data set using the methodology outlined
in the Receiving Water Characteristics memorandum (ERG,
2019d). ERG used the average annual flow values calculated
using the Enhanced Runoff Method (EROM). See the
memorandum "Monthly Water Quality Modeling Analysis
and Supporting Documentation for the 2019 Steam Electric
Supplemental Environmental Assessment" (the Monthly
Water Quality Modeling memorandum) (ERG, 2019j)
regarding the flow values used in the supplemental monthly
analysis.
C-15
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Appendix C— Water Quality Module Methodology
Table C-l. Input Variables with Values from Site-Specific Data Sources
Input Yiirhihk-
Input ( ;ik'iior\ iiiid
Description
Site-Specific l);it;i Soiiivc
\
keceiv nig walerdiamclensiic
for rivers and streams.
Receiving water velocity.
1 lie 1 \> \ eMiacled average annual \ clout} \allies from ilie
NHDPlus Version 2 data set using the methodology outlined
in the Receiving Water Characteristics memorandum (ERG,
2019g). The NHDPlus Version 2 data set includes estimated
mean annual velocity values for each stream reach within the
network using the Jobson Method (Jobson, 1996) and the
estimated mean annual flow values.
Len
Receiving water characteristic
for rivers and streams.
Length of stream reach.
The EPA estimated the stream reach length based on outfall
locations using the methodology described in the Receiving
Water Characteristics memorandum (ERG, 2019d).
Qlake
Receiving water characteristic
for lakes, ponds, and reservoirs.
Average discharge flow exiting
the lake/pond system.
The EPA extracted average annual flow values from the
NHDPlus Version 2 data set using the methodology outlined
in the Receiving Water Characteristics memorandum (ERG,
2019d). ERG used the average annual flow values calculated
using EROM.
Area
Receiving water characteristic
for lakes, ponds, and reservoirs.
Surface area of the lake, pond,
or reservoir.
The EPA estimated the surface area of the lake, pond, or
reservoir based on the surface area field from the NHDPlus
Version 2 Lake Morphometry data layer, or site-specific data
as described in the Receiving Water Characteristics
memorandum (ERG, 2019d).
dz,lake
Receiving water characteristic
for lakes, ponds, and reservoirs.
Depth of the lake, pond, or
reservoir.
The EPA estimated the depth of the lake, pond, or reservoir
based on the mean depth field from the NHDPlus Version 2
Lake Morphometry data layer, or site-specific data as
described in the Receiving Water Characteristics
memorandum (ERG, 2019d).
dw,lake
Receiving water characteristic
for lakes, ponds, and reservoirs.
Depth of the water column.
The EPA estimated the depth of the lake, pond, or reservoir
based on the mean depth field from the NHDPlus Version 2
Lake Morphometry data layer, or site-specific data as
described in the Receiving Water Characteristics
memorandum (ERG, 2019d).
C-16
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Appendix C— Water Quality Module Methodology
Table C-2. Input Variables and Constants with Globally Assigned Values
Inpul \ iiriiihlo
or ('(iiisliinl
Description
Assigned
Value
K;iliou;ile/l);il;i Source
Lied bcdiiiiciil porosis.
U.o cm. cm
Bed bcdinieiil porosis i;, the \ olunie of w aler per
volume of benthic space with typical values ranging
between 0.4 and 0.8 (U.S. EPA, 1998). The EPA
selected an average value to use for this input
variable.
bsd
Bed sediment bulk
density.
1 g/cm3
Bed sediment bulk densities typically range between
0.5 to 1.5 g/cm3 (U.S. EPA, 1998). The 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, 1998). The EPA selected an average value to
use for this input variable.
ksw
Degradation rate for
water column.
0/day
The EPA assumed no loss from pollutant degradation
in the water column, as an environmentally
conservative assumption.
kvd
Water column
volatilization loss rate
constant.
0/day
The EPA selected a volatilization rate of 0 for
nonvolatile pollutants (i.e., all pollutants except
mercury).
ksed
Degradation rate for
sediment.
0/day
The EPA assumed no loss from pollutant degradation
in the sediment, as an environmentally conservative
assumption.
WB
Rate of burial.
0/day
The EPA assumed no pollutant loss from burial within
the waterbody sediments, as an environmentally
conservative assumption.
©water
Temperature correction.
1.026
(unitless)
The EPA selected the temperature correction factor
based on the value provided in U.S. EPA (1998).
K-g (Rivers)
Gas phase transfer
coefficient for rivers or
streams.
36,500 m/yr
(100 m/day)
The EPA selected the gas phase transfer coefficient
for rivers and streams based on the value provided in
U.S. EPA (1998).
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)
The EPA selected the drag coefficient based on the
value provided in U.S. EPA (1998).
Pa
Density of air
corresponding to water
temperature.
0.0012
g/cm3
The EPA selected the density of air corresponding to
water temperature based on the value provided in U.S.
EPA (2005a).
Pw
Density of water
corresponding to water
temperature.
1 g/cm3
The EPA selected the density of water corresponding
to water temperature based on the value provided in
U.S. EPA (2005a).
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.
C-17
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Appendix C— Water Quality Module Methodology
Table C-2. Input Variables and Constants with Globally Assigned Values
Inpul \ iiriiihlo
or ('(iiisliinl
Description
Assigned
Value
K;ilion;ilc/l);il;i Source
Ivd,,
Suspended bcdlllicill-
surface water partition
coefficient.
See
Table C-4
The impended s>edinieni pariiuon coefficient
describes the partitioning of a pollutant between
sorbing material, in this case suspended sediment and
surface water. The EPA identified U.S. EPA (2005a)
as the primary source for the pollutant-specific
suspended sediment partition coefficients.
Kdbs
Bottom sediment-pore
water partition
coefficient.
See
Table C-4
The bottom sediment partition coefficient describes
the partitioning of a pollutant between sorbing
material, in this case bottom sediment and pore water.
The EPA identified U.S. EPA (2005a) as the primary
source for the pollutant-specific bottom sediment
partition coefficients.
X2
Dimensionless viscous
sublayer thickness.
4
(unitless)
The EPA selected the viscous sublayer thickness value
based on the value provided in U.S. EPA (2005a).
(J-W
Viscosity of water
corresponding to water
temperature.
0.0169
g/cm-s
The EPA selected the viscosity of water value based
on the value provided in U.S. EPA (2005a).
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
pollutants. Mercury is the only volatile pollutant
included in the IRW Model. Therefore, the assumed
model default value is set to Henry's Law Constant
for mercury at 298 K.
Thic
Temperature of Henry's
Law Constant.
298 K
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 pollutants. Mercury is the
only volatile pollutant included in the IRW Model.
Therefore, the assumed model default value is set to
the molecular weight for mercury.
C-18
-------
Appendix C— Water Quality Module Methodology
Table C-3. Input Variables with Values from Regional Data Sources
Input Variable
Description
Assigned
Value
Regional Data Source
TSS
Total suspended solids.
See
Table C-5
The EPA used the geometric mean of the regional and
national TSS concentrations determined as part of the
Human and Ecological Risk Assessment of Coal
Combustion Residuals (U.S. EPA, 2014).
WlQ:
Wind velocity 10 m above
the water surface.
See
Figure C-l
National Climatic Data Center national mean annual
wind speed GIS coverage, downloaded on May 12,
2011 (NCDC, 2011). The EPA selected, as an
environmentally conservative estimate, the lower of
the wind speed range values for the analysis.
Ta
Air temperature.
See
Figure C-2
National Climatic Data Center national mean annual
temperature GIS coverage, downloaded on May 12,
2011 (NCDC, 2011). The EPA selected, as an '
environmentally conservative estimate, the lower of
the air temperature range values for the analysis.
Tw
Temperature of the
surface water.
See
Table C-6
The EPA used the regional surface temperatures
determined as part of the Human and Ecological Risk
Assessment of Coal Combustion Residuals (U.S. EPA,
2014).
STATES
kN SPEED OF WIND (MPH)
- ANNUAL -
A <6.0
B 6.0-6.9
C 7.0-7.9
D 8.0-8.9
E 9.0-9.9
F 10.0-10.9
G 11.0-11.9
H > 11.9
TITLE
Figure C-l. National Climatic Data Center National Mean Annual Wind Speeds
ANNUAL
mean wind speed
C-19
-------
Appendix C— Water Quality Module Methodology
STATES
DAILY AVG TEMP (DEG_F)
- ANNUAL -
A < 32.0
B 32.0-40.0
C 40.1 - 45.0
D 45.1 - 50.0
E 50.1 - 55.0
F 55.1 - 60.0
G 60.1 -65.0
H 65.1 - 70.0
I > 70.0
TITLE
Figure C-2. National Climatic Data Center National Mean Annual Temperatures
Table C-4. Partition Coefficients
Pollutant
Suspended Sediment-
Water Partition
Coefficient (Kdsw)
(mL/g)
Bottom Sediment-Pore
Water Partition
Coefficient (Kdbs)
(mL/g)
Arsenic
7.900
250
Cadmium
79,000
2,000
Copper
50,000
3,200
Lead
500,000
40,000
VIereun (II)
200,000
79,000
Nickel
20,000
7,900
Selenium (IV)
25,000
4,000
Thallium
13,000
20
Zinc
100,000
13,000
Source: U.S. EPA, 2005a.
¦ ANNUAL .
MEAN DAILY AVERAGE TEMPERATURE
C-20
-------
Appendix C— Water Quality Module Methodology
Table C-5. TSS Concentrations in Surface Waters
Ihdrologie
Region ;l
Number of
Measurements
Nil in her ol
Annual Medians
Annual Median TSS ung/l.)
(log triangular distribution)
Miu
Max
Weighted
(ieouielrie
Mean
1
9,007
33
3.2
40
8
2
47,202
38
10
316
32
3
43,395
36
6.3
79
25
4
29,577
37
6.3
794
25
5
39,900
38
4
100
25
6
4,137
28
5
316
16
7
34,494
37
32
1,585
63
8
46,231
38
50
316
158
9
3,254
35
13
3,162
32
10
62,791
38
10
398
126
11
48,969
38
25
794
200
12
7,280
35
40
1,995
79
13
13,974
37
32
79,433
200
14
26,699
38
16
5,012
158
15
9,162
37
20
19,953
200
16
19,965
33
4
2,512
16
17
173,136
37
2
316
6
Lakes (national)
4,360
99
1
398
25
Source: U.S. EPA, 2014; Legacy STORET database.
a - For rivers and streams, the EPA used the weighted geometric mean TSS concentration for the corresponding
hydrogeologic region. For lakes, ponds, and reservoirs, the EPA used a weighted national geometric mean.
C-21
-------
Appendix C— Water Quality Module Methodology
Table C-6. Regional Surface Water Temperatures
ll\(lrnlo^ic Roiiion
(liniiik-
Surl'iico \\;Kcr
Tciii|H-r;iliiiv (°C)
Surl'iico \\;ilcr
Tern pom In re (k)
1
North
14
287
2
North
16
289
3
South
21
294
4
North
14
287
5
North
17
290
6
South
18
291
7
North
15
288
8
South
20
293
9
North
10
283
10
North
13
286
11
South
17
290
12
South
21
294
13
South
16
289
14
South
9
282
15
South
17
290
16
South
9
282
17
North
11
284
Source: U.S. EPA, 2014; Legacy STORET database.
C-22
-------
Appendix C— Water Quality Module Methodology
Table C-7. NRWQC and MCLs
Polliiliinl
1 \\ Aculo
\ R\\ („)(' ', h
(iiiii/l.)
l \\ Chronic
\ R\\ („)(' ', h
(inii/l.)
llll WO
\ R\\ („)(';, h
(inii/l.)
llll ()
\R\\Q( ,h
(nig/l.)
MCI.
(inii/l.)
Arsenic
0.34d
0.15d
0.000018e
0.00014e
0.01
Cadmium
0.0018 4f
0.00072 V
--
--
0.005
Copper
0.013 d,g
0.009 d,g
1.3
—
1.3 (Action
Level); 1.0 h
Lead
0.065 d
0.0025 d
--
--
0.015 (Action
Level)
Mercury
0.0014d
0.00077 d
--
--
0.002e
Nickel
0.47 d
0.052 d
0.61
4.6
--
Selenium
Lentic: 0.0451
Lotic: 0.0941
Lentic: 0.0015J
Lotic: 0.0031J
0.17
4.2
0.05
Thallium
--
--
0.00024
0.00047
0.002
Zinc
0.12d
0.12d
7.4
26
5 h
Acronyms: MCL (Maximum Contaminant Level); mg/L (milligrams per liter); NRWQC (National Recommended
Water Quality Criteria).
Source: U.S. EPA, 2009a, 2009c, 2016c, and 2016d.
a - designates instances where a benchmark value does not exist for the pollutant, or the benchmark value is a
secondary standard.
b - Unless otherwise noted, 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 from the EPA's
National Recommended Water Quality Criteria (U.S. EPA, 2009c).
c - Unless otherwise noted, pollutant concentrations were compared to the MCL from the EPA's National Primary
Drinking Water Regulations (U.S. EPA, 2009a).
d - Benchmark value is expressed in terms of the dissolved pollutant in the water column,
e - Benchmark value is for inorganic form of pollutant.
f - The cadmium benchmark values are based on the NRWQC from the EPA's Aquatic Life Ambient Water Quality
Criteria for Cadmium - 2016 (U.S. EPA, 2016d).
g - The 2009 NRWQC for copper are calculated using the biotic ligand model; therefore, there is no national value.
For this analysis, the EPA used the 2002 NRWQC values (U.S. EPA, 2002).
h - The EPA evaluated both the action level of 1.3 mg/L and the secondary (nonenforceable) drinking water
standard of 1.0 mg/L for copper. The results presented in Section 4 of the report and Appendix F are based on the
number of immediate receiving waters with exceedances of the lower secondary drinking water standard (1.0 mg/L).
i - The selenium benchmark values are based on the NRWQC from the EPA's Aquatic Life Ambient Water Quality
Criteria for Selenium - Freshwater 2016 (U.S. EPA, 2016c). The selenium acute NRWQC, as calculated here,
assumes a background selenium concentration of zero and an intermittent exposure duration of 1 day, which is the
shortest exposure period to be used when applying the criterion.
j - The selenium benchmark values are based on the NRWQC from the EPA's Aquatic Life Ambient Water Quality
Criteria for Selenium - Freshwater 2016 (U.S. EPA, 2016c). The selenium chronic water column NRWQC applies
only in the absence of fish tissue measurements. Use of this water column benchmark value may therefore over- or
underestimate the number of exceedances.
C-23
-------
Appendix C— Water Quality Module Methodology
IRW Model: Water Quality Module Methodology Limitations and Assumptions
The limitations and assumptions of the Water Quality Module include the following:
• The module is based on annual-average pollutant loadings from the two evaluated
wastestreams at coal-fired power plants and annual-average flow rates within the
immediate receiving waters. The module does not consider temporal variability (e.g.,
seasonal differences, storm flows, low-flow events, catastrophic events) and does not
consider the potential for pollutants to accumulate in the environment over extended
discharge periods covering multiple years. The effect of this limitation on the Water
Quality Module outputs is undetermined, but it is likely to underestimate the long-
term accumulation of pollutants within lakes, ponds, and reservoirs; this may
subsequently underestimate the wildlife and human health impacts resulting from
exposure to pollutants in these systems. To illustrate potential short-term temporal
variability, the EPA also performed Water Quality Module runs using average
monthly pollutant loadings and receiving water flow rates. This analysis is
documented in the Monthly Water Quality Modeling memorandum (ERG, 2019j) and
the results are discussed in Section 4.4 of the report.
• The module represents only the waterbody concentration within the immediate
discharge zone (i.e., approximately 1 to 5 miles from the outfall) and does not
calculate pollutant concentrations in downstream waters. This limitation results in a
potential underestimate of the extent of surface waters with environmental and human
health impacts under baseline, as well as changes under the regulatory options.
However, the EPA performed a downstream analysis using the outputs from a
separate pollutant fate and transport model. This analysis is documented in the
memorandum "Downstream EA Modeling Methodology and Supporting
Documentation for the 2019 Steam Electric Supplemental Environmental
Assessment" (ERG, 2019g), and the results are discussed in Section 4.5 of the report.
• The module does not take into consideration pollutant speciation within the receiving
stream. This limitation is particularly relevant to the wildlife impact analysis, as many
of the ecological impacts are tied to a specific pollutant species. For example,
inorganic arsenic is typically more toxic to aquatic life than organic arsenic. This
limitation results in a potential overestimation of the number of immediate receiving
waters with exceedances of water quality benchmark values for inorganic forms of
the pollutant (e.g., the human health NRWQCs for arsenic).
• The module assumes that equilibrium is quickly attained within the waterbody
following discharge and is consistently maintained between the water column and
surficial bottom sediments. This assumption is especially significant regarding
pollutant equilibrium within lakes, ponds, and reservoirs. The module 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, pond, or reservoir is at equilibrium. As a result, the module
outputs do not reflect the potential spatial and temporal variability of pollutant
concentrations within the immediate receiving water, and potentially underestimate
the existence of isolated "hot spots" of elevated pollutant concentrations.
C-24
-------
Appendix C— Water Quality Module Methodology
• The module assumes that pollutants dissolved or sorbed within the water column and
bottom sediments can be described by a partition coefficient. The EPA used a single
partition coefficient to characterize the pollutant in the immediate receiving waters.
The partition coefficient in a specific waterbody will be influenced by geochemical
parameters (e.g., pH and presence of particulate organic matter and other sorbing
material). The EPA used a mean or median value for the partition coefficients (central
tendency of Kd values) based on data gathered from published sources, statistical
analysis of retrieved data, geochemical modeling, and expert judgment (U.S. EPA,
2005a). The result of this assumption on the Water Quality Module outputs is
undetermined due to site-specific factors.
• The module assumes that pollutants sorbed to bottom sediments are considered a net
loss from the water column. This assumes that bottom 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 column. This assumption results in a potential overestimation of
pollutant concentrations within the bottom sediments and a potential underestimation
of pollutant concentrations within the water column and downstream reaches.
• The module assumes a pollutant burial rate of zero within bottom sediment. This is an
environmentally protective assumption that might overestimate impacts to sediment
receptors to some degree. The burial rate constant is a function of the deposition of
sediments from the water column to the upper bed and accounts for the soil eroding
into a waterbody becoming bottom sediment rather than suspended sediment. The rate
of burial used for each segment of a waterbody may be difficult to obtain (U.S. EPA,
1998). The EPA had neither measured values nor the data to determine burial rates
for each immediate receiving water. This assumption results in a potential
overestimation of impacts in the bottom sediment.
• The module does not take into account ambient background pollutant concentrations
or contributions from other point and nonpoint sources. Also, the pollutant loadings
included in the module are not representative of the total pollutant loadings from
coal-fired power plants, as there are several wastestreams that are not included in the
analysis (e.g., fly ash transport water, leachate, stormwater runoff, metal cleaning
wastes, and coal pile runoff). Because of this approach, the module likely
underestimates the number and magnitude of benchmark value exceedances at
baseline and under the regulatory options, which contributes to uncertainty in the
number of environmental and human health improvements or impacts under the
regulatory options relative to baseline.
C-25
-------
Appendix D — Wildlife Module Methodology
APPENDIX D
WILDLIFE MODULE METHODOLOGY
This appendix presents the model equations, input variables and constants, pollutant benchmark
values, and methodology limitations/assumptions for the Wildlife Module of the Immediate
Receiving Water (IRW) Model, which quantifies impacts to 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 coal-fired
power plants.
• Wildlife (minks and eagles)2 that consume fish from receiving waters in the
immediate discharge zone of coal-fired power plants.
For the supplemental environmental assessment (Supplemental EA), the EPA estimated pollutant
concentrations in the immediate receiving water and sediment using the Water Quality Module
(see Appendix C). The Wildlife Module uses these concentrations as inputs.
The following tables describe the input requirements and data sources used in the Wildlife
Module:
• Table D-l. Threshold Effect Concentrations (TECs) for Sediment Biota.
• Table D-2. Bioconcentration Factors (BCFs) and Bioaccumulation Factors (BAFs) for
Trophic Level 3 (T3) and Trophic Level 4 (T4) Fish.
• Table D-3. No Effect Hazard Concentrations (NEHCs) for Minks and Bald Eagles.
Methodology Updates Subsequent to the 2015 Final EA
Since the completion of the 2015 Final EA, the EPA incorporated the following updates to the
equations, data sets, and parameter values used in the Wildlife Module:
• Sediment threshold effect concentrations: For the 2015 Final EA, the EPA used
threshold effect levels (TELs) referenced in a single study (NOAA, 2008) as the
benchmark values for impacts to sediment biota. For the Supplemental EA, the EPA
replaced the TELs with threshold effect concentrations (TECs) developed through a
consensus-based process (MacDonald et al., 2000). MacDonald et al. (2000) used six
sets of sediment quality guidelines to develop the TECs.
• Sediment benchmark value for selenium: For the 2015 Final EA, the EPA did not
identify a sediment benchmark value for selenium. For the Supplemental EA, the
EPA identified and used a sediment benchmark value for selenium developed by
Lemly (2002) using a long-term selenium concentration data set collected from 1970
through 1996 at Belews Lake, NC. Lemly recommended 2 micrograms selenium per
gram of sediment (|ig/g, equivalent to g/kg) as a toxicity benchmark value that would
2 The EPA selected minks and eagles to represent national-scale impacts from coal-fired power plants because their
habitats cover the entire United States (i.e., can be used for a national assessment).
D-l
-------
Appendix D — Wildlife Module Methodology
be protective of reproductive success in fish and aquatic birds that bioaccumulate
selenium through consumption of benthic organisms.
• Revised Equation D-l: The TELs used in the 2015 Final EA were expressed based
on a wet weight basis, while the TECs used in the Supplemental EA are expressed on
a dry weight basis. To accommodate this change, the EPA revised Equation D-l to
convert the pollutant concentration in sediment (Cbs) from a volume basis (mg/L) to a
dry weight basis (mg/kg) using the assumed values in the Water Quality Module for
bed sediment bulk density and porosity.
• Cadmium bioconcentration factor: In the 2015 Final EA, the EPA used a cadmium
bioconcentration factor (BCF) of 270 liters per kilogram (L/kg), derived from
Kumada et al. (1972), and applied this BCF to both trophic level 3 (T3) and trophic
level 4 (T4) fish. For the Supplemental EA, the EPA calculated an updated cadmium
BCF using the bioaccumulation data sets available in Appendix G of the U.S. EPA's
Aquatic Life Ambient Water Quality Criteria for Cadmium - 2016 (U.S. EPA,
2016d), which presents a set of "Acceptable Bioaccumulation Data" that were
reviewed during development of the revised criteria. The EPA's calculations, which
resulted in an updated cadmium BCF of 113 L/kg for both trophic levels, are
documented in the Cadmium BCF Calculation spreadsheet (ERG, 2019k).
IRW Model: Wildlife Module Equations. Input Variables, and Impact Analysis
Impact to Aquatic Life Receptors from Direct Contact with Sediment. The EPA determined the
potential negative impact to aquatic organisms from direct contact with the sediment in
immediate receiving waters by comparing the pollutant concentration in the sediment (Cbs from
the Water Quality Module) to the consensus-based TECs for sediment biota listed in Table D-l.
The Wildlife Module expresses this comparison as a hazard quotient (HQ). An HQ of higher
than one (i.e., pollutant concentration exceeds the TEC) indicates a potential impact to the
exposed organism. The EPA used Equation D-l to calculate the HQ for sediment biota.
Equation D-l
HO (§9) - (ttU
Qsed TECsed
Where:
HQsed
=
Hazard quotient for contact with sediment
Output from Equation D-l
Cbs
=
Total pollutant concentration in sediment
(milligrams per liter (mg/L))
Water Quality Module output
from Equation C-5
bsd
Bed sediment bulk density (gram per cubic
centimeter (g/cm3)) or (kilogram per liter
(kg/L))
Globally assigned value of 1
g/cm3 (see Table C-2)
bsp
=
Bed sediment porosity (cubic centimeter per
cubic centimeter (cm3/cm3))
Globally assigned value of 0.6
cm3/cm3 (see Table C-2)
D-2
-------
Appendix D — Wildlife Module Methodology
TECsed
=
Threshold effect concentration for sediment
Receptor-specific value
(milligrams per kilograms (mg/kg), dry
(see Table D-l)
weight basis)
Adverse Effects to Piscivorous Wildlife. The EPA determined the potential negative impact to
piscivorous wildlife (i.e., wildlife that consume fish) from the ingestion of contaminated fish by
calculating fish tissue concentrations and comparing these concentrations to NEHCs as the
selected ecological benchmark values. Equation D-2 calculates pollutant concentrations in fish
for the evaluated pollutants, except for mercury. Because the more toxic form of mercury is
methylmercury, the 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.
The EPA compared the calculated T3 fish tissue concentration to the NEHC for minks and the
calculated T4 fish tissue concentration to the NEHC for eagles (see Table D-3). The Wildlife
Module expresses this comparison as an HQ. The EPA used Equation D-4 to calculate HQ
values for arsenic, cadmium, copper, lead, mercury (as methylmercury), nickel, selenium,
thallium, and zinc.
Equation D-2
CfishT = Cwc x bcft
Equation D-3
CfishT = (0.15 x Cdw) x BCFt
Where:
CfishT
Pollutant concentration in fish (wet weight),
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 Module output
from Equation C-3
Cdw
=
Dissolved pollutant concentration in water
(mg/L)
Water Quality Module output
from Equation C-4
0.15
=
Fraction of dissolved total mercury as
dissolved methylmercury (unitless)
Globally assigned value (U.S.
EPA, 2005b)
BCFt
Bioconcentration factor or bioaccumulation
factor for specified trophic level (liters per
kilogram (L/kg))
Pollutant-specific value
(see Table D-2)
D-3
-------
Appendix D — Wildlife Module Methodology
Equation D-4
Where:
HQi
=
Hazard quotient for ingestion of fish
Output from Equation D-4
CfishT
Pollutant concentration in fish (wet weight),
where T represents trophic level T3 or T4
(mg/kg)
Output from Equation D-2 or
Equation D-3
NEHC
=
No effect hazard concentration (|ig/g)
Receptor- and pollutant-
specific (see Table D-3)
Table D-l. TECs for Sediment Biota
Polliiliinl ill Wildlife
llll|)ilCl ASSOSSIIU'IK
i r.c (nig/kg)
Noll's/Sou m.*
Arsenic
9.79
MacDonald et al., 2000.
Cadmium
0.99
MacDonald et al., 2000.
Copper
31.6
MacDonald et al., 2000.
Lead
35.8
MacDonald et al., 2000.
Mercury
0.18
MacDonald et al., 2000.
Nickel
22.7
MacDonald et al., 2000.
Selenium
2
Lemly, 2002.
Thallium
None identified
The EPA could not complete the analysis for this pollutant - no
TEC available for comparison.
Zinc
121
MacDonald et al., 2000.
Acronyms: mg/kg (milligrams per kilogram); TEC (Threshold Effect Concentration).
n _ CfishT
hq'~nehc
D-4
-------
Appendix D — Wildlife Module Methodology
Table D-2. BCFs and BAFs for T3 and T4 Fish
Polliiliini
IK I-'or li\l-
l-";iclor for 13 l-'isli
(l./k»)
I- ;iclor lor 14 l-'isli
(l./k»)
Source
Arsenic
BCF
4
4
Barrows et al., 1980.
Cadmium
BCF
113
113
ERG, 2019k.
Coppera
BCF
36
36
U.S. EPA, 1980b.
Lead
BAF
46
46
Stephan, 1993.
Methylmercury
BAF
1.6 x 106
6.8 x 106
U.S. EPA, 1997a.
Nickelb
BCF
0.8
0.8
Calamari et al., 1982.
Selenium
BAF
490
1,700
Lemly, 1985.
Thallium
BCF
34
130
Barrows et al., 1980
and Stephan, 1993.
Zinc
BCF
350
350
Murphy et al., 1978.
Acronyms: BAF (bioaccumulation factor); BCF (bioconcentration factor); L/kg (liters per kilogram); T3 (trophic
level 3); T4 (trophic level 4).
a - BCF not specific to a particular trophic level; applies to fish consumed by humans,
b - Nickel (soluble salts).
Table D-3. NEHCs for Minks and Bald Eagles
Polliiliini in
\\ ilrililc Impiicl
Assessment
M.IK lor Mink
(13 l-'isli) (.uii/ji)
M.IK lor l.;i»lc
(14 l-'isli) (fiii/ii)
Noles
Arsenic
7.65
22.4
Cadmium
5.66
14.7
Copper
41.2
40.5
Lead
34.6
16.3
Methylmercury
0.37
0.5
No NEHC for methylmercury. The EPA compared
the modeled methylmercury concentrations to the
total mercury NEHC, which may underestimate
the impact to wildlife.
Nickel
12.5
67.1
Selenium
1.13
4
Thallium
None identified
None identified
The EPA could not complete the analysis for this
pollutant - no NEHC available for comparison.
Zinc
904
145
Source: USGS, 2008.
Acronyms: |ig/g (micrograms per gram); NEHC (No Effect Hazard Concentration); T3 (trophic level 3); T4 (trophic
level 4).
D-5
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Appendix D — Wildlife Module Methodology
IRW Model: Wildlife Module Methodology Limitations and Assumptions
The limitations and assumptions of the Wildlife Module include the following:
• Cumulative Risks Across Exposure Pathways. The Wildlife Module does not
consider cumulative risks across exposure pathways. For example, the modeled
impacts to wildlife from ingesting contaminated fish do not consider the risk from
direct contact with surface water. The receptors chosen for the wildlife ingestion
model, minks and eagles, do not spend much time in contact with the surface water;
therefore, not including the impact of direct contact with surface water should only
minimally underestimate the impacts. In addition, the Wildlife Module 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, because it is likely that the dose from the food source is far greater
than the dose from water ingestion. However, the Wildlife Module may
underestimate bioaccumulation among aquatic species that do ingest relatively greater
volumes of water.
• Use of BCFs and BAFs. Where available, the EPA used BAFs to represent the
accumulation of pollutants in fish tissue (e.g., for selenium and methylmercury).
Otherwise, the EPA used BCFs, which do not account for accumulation of pollutants
via the food web. For certain pollutants, exposure via the aquatic food web can be
more significant than exposure via ingestion of water.3 The result of this limitation on
the Wildlife Module output for those pollutants that use a BCF is an under-
representation of pollutant bioaccumulation in fish tissue where exposure via the
aquatic food web is significant. However, BCFs are useful in a screening-level
assessment and appropriate for a national-level EA, where site-specific data are not
available and collection of site-specific data is not viable. The limitation of using a
single, national-level BAF/BCF is undetermined due to site-specific factors.
• Receptor Populations Evaluated. The EPA considered the limitations and made
multiple assumptions in choosing receptor populations to evaluate. First, the EPA
assumed that, because this is a national model, the receptor species and receiving
water occur together (i.e., all receiving waters evaluated in the Wildlife Module are
habitat for the receptor species, even though that may not always be the case). In
addition, due to the scope of the project, the EPA considered a limited number of
species as receptors. For the wildlife receptors, the 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 Wildlife Module inherently excludes
the impacts to critical assessment endpoints such as threatened and endangered
species.
3 The EPA Office of Water Health and Ecological Criteria Division agrees that all the routes (food, sediment, and
water) by which fish and shellfish are exposed to highly bioaccumulative pollutants may be important in
determining the accumulation in fish tissue and the subsequent transfer to human receptors. In addition, the EPA
agrees that distributions of BAFs/BCFs may be better than single BAFs/BCFs because they account for changes in
bioaccumulation/bioconcentration rates at different water concentrations. The EPA is working to develop BAF/BCF
distributions for several pollutants to better represent the bioaccumulation in aquatic organisms.
D-6
-------
Appendix D — Wildlife Module Methodology
• Wildlife Receptor Diet. To provide an environmentally protective estimate of dietary
pollutant exposure, the Wildlife Module assumes that the diet of adult minks and bald
eagles consists entirely of fish inhabiting the immediate receiving waters. The EPA
believes this assumption is reasonable based on the following two factors:
(1) It is possible that in some habitats the diet of both minks and eagles consists
largely of fish, and the EPA aims to be protective of wildlife across all
habitats. For example, studies have shown dietary composition as high as 75
and 85 percent fish for bald eagles and minks, respectively (U.S. EPA, 1993).
In addition, it is likely that the other organisms consumed by minks and eagles
are also contaminated with the pollutants of concern and are unaccounted for
in the model.
(2) With respect to home ranges, the case study water quality modeling results in
Section 8 of the 2015 Final EA demonstrate that pollutants discharged from
coal-fired power plants can continue to occur at elevated levels downstream
from the immediate receiving waters, contaminating fish outside of immediate
receiving waters and resulting in additional potential for pollutant exposure
among piscivorous wildlife.
Overall, however, this assumption likely results in a potential overestimation of
exposure to the modeled species. The Wildlife Module also assumes that the diet
of adult minks consists entirely of T3 fish and the diet of bald eagles consists
entirely of T4 fish. These assumptions likely result in a potential overestimation
of exposure among eagles (whose diet may also include T3 fish) and an
underestimation of exposure among eagles (whose diet may also include T4 fish).
• Bioavailability and Speciation of Pollutants. The IRW Model assumes that all forms
of a pollutant are equally bioavailable to ecological receptors. Therefore, data inputs
for the Wildlife Module include total pollutant concentration in the water column
(i.e., dissolved particles 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
waterbody. Because of bioavailability and pollutant speciation assumptions made for
the wildlife impact assessment, the impact to receptors may be over- or
underestimated.
• Indirect Ecological Effects. The Wildlife Module 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 Module assumes that
the receiving waterbody 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 stratum; for example, if the hypolimnion (i.e., lowest stratum of a lake) has a much
D-7
-------
Appendix D — Wildlife Module Methodology
lower pH than the epilimnion (i.e., upper stratum), the concentration or speciation of
many pollutants may vary between the two layers. Therefore, bottom-dwelling
organisms would be exposed to different pollutant species and concentrations. Due to
the complexity of these relationships and necessity for site-specific data, none of the
impact analyses considered the stratification of receiving waters. The effect of this
limitation on the Wildlife Module outputs is undetermined.
• Multiple Pollutant Exposures. According to the EPA's Steam Electric Power
Generating Point Source Category: Final Detailed Study Report, Document No.
EPA-821-R-09-008 (U.S. EPA, 2009d), receptors will be exposed to multiple
constituents simultaneously. However, the Wildlife Module examines the impact of
individual pollutants to receptors and does not take into account how the interaction
of multiple pollutants impacts the receptors. For example, the EPA did not consider
the impact of mercury on the uptake or toxicity of selenium. There is evidence in the
literature (Chapman et al., 2009) that these two compounds interact in the
environment to decrease each other's impact on a receptor. Conversely, the
interaction of other pollutants may increase the impact to a receptor. However,
because the TECs and NEHCs 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. The EPA used TECs and NEHCs as described above to
identify potential adverse impacts to aquatic organisms. These benchmark values
represent the concentrations below which adverse effects are not expected to occur in
the exposed organism; an exceedance of these thresholds does not necessarily
demonstrate that the exposed organism will experience adverse effects. Use of these
benchmark values therefore results in an environmentally protective impact estimate.
D-8
-------
Appendix E — Human Health Module Methodology
APPENDIX E
HUMAN HEALTH MODULE METHODOLOGY
This appendix presents the model equations, input variables and constants, benchmark values,
and methodology limitations/assumptions for the Human Health Module of the Immediate
Receiving Water (IRW) Model. The module quantifies human health impacts to recreational and
subsistence fishers (adult and child cohorts) that consume fish exposed to pollutants as a result of
discharges from coal-fired power plants. Additionally, the EPA performed an environmental
justice (EJ) analysis that evaluated the differences in human health impacts across race
categories due to differing fish consumption rates.
For the supplemental environmental assessment (Supplemental EA), the EPA estimated pollutant
concentrations in fish using the Model Wildlife Module (see Appendix D). The Human Health
Module uses these concentrations as inputs.
The following tables describe the input requirements and data sources used in the Human Health
Module:
• Table E-l. Calculation of Consumption Ratio for Trophic Level 3 (Ft3) and Trophic
Level 4 (Ft4) Fish.
• Table E-2. Assigned Values for Input Variables and Constants.
• Table E-3. Cohort-Specific Input Variables.
• Table E-4. Environmental Justice Analysis: Cohort-Specific Input Consumption Rate
by Race Category.
• Table E-5. Pollutant-Specific Benchmark Values.
Methodology Updates Subsequent to the 2015 Final EA
The EPA did not identify any necessary revisions to the equations, data sets, or parameter values
used in the Human Health Module since the completion of the 2015 Final EA.
IRW Model: Human Health Module Equations
The EPA estimated the pollutant concentrations in fish fillets consumed by humans (i.e., dose)
using an assumed consumption ratio of trophic level 3 (T3) and trophic level 4 (T4) fish and site-
specific pollutant concentrations in fish. For each cohort, the EPA calculated the average daily
dose (ADD) of the pollutant from eating fish and compared this ADD to non-cancer oral
reference doses (RfDs). The Human Health Module expresses this comparison as a hazard
quotient (HQ). An HQ of higher than one (i.e., pollutant dosage exceeds oral RfD) indicates a
potential non-cancer threat to the human cohort. The EPA also calculated a lifetime average
daily dose (LADD) and a corresponding lifetime excess cancer risk (LECR) for each cohort.
This study used the one-in-a-million cancer risk benchmark when evaluating exposures
associated with fish consumption.
E-l
-------
Appendix E — Human Health Module Methodology
The EPA used the equations presented below to calculate the pollutant concentration in the fish
fillet; the ADD for arsenic, cadmium, copper, lead, mercury, nickel, selenium, thallium, and
zinc; the associated non-cancer threat HQ; and the LADD and LECR values for arsenic.
Equation E-l
Cfish_fillet = Fl3 x CfishT3F + FT4 x CfishT4F
Where:
Cfish fillet
Average fish fillet concentration ingested by
humans (milligrams per kilograms (mg/kg))
Output from Equation E-l
CfishT3F
Concentration of contaminant in fish at
trophic level 3 (mg/kg)
Site-specific Wildlife Module
output from Equation D-2 and
Equation D-3
CfishT4F
Concentration of contaminant in fish at
trophic level 4 (mg/kg)
Site-specific Wildlife Module
output from Equation D-2 and
Equation D-3
F T3
=
Fraction of trophic level 3 fish intake
(unitless)
0.36 (see calculation below)
F T4
=
Fraction of trophic level 4 fish intake
(unitless)
0.64 (see calculation below)
To determine the fraction of T3 and T4 fish intake for human cohorts, the EPA started with the
data presented in the 2011 Emissions Factor Handbook, Table 10-74 (U.S. EPA, 201 lc). The
EPA then completed the following analysis:
1. Assigned trophic levels to fish if not already listed in the table.
2. Totaled the quantities of fish consumed by trophic level.
3. Determined fraction of fish consumed at each trophic level.
Table E-l documents the data and analysis performed. The 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 IRW Model.
Equation E-2 calculates the ADD, which is the daily intake of the contaminant from fish
ingestion. Based on a literature review (including references from the EPA and the Agency for
Toxic Substances and Disease Registry (ATSDR)), arsenic in fish is mostly in the organic form
and not harmful to humans. The inorganic form of arsenic is harmful to humans. The EPA's
1997 document, Arsenic and Fish Consumption, reported the inorganic arsenic concentration in
fish as between 0.4 and 4 percent of the total arsenic accumulating in fish (U.S. EPA, 1997b).
The EPA estimated the inorganic arsenic concentration in fish by assuming that four percent of
the total arsenic is inorganic. The EPA used this inorganic arsenic concentration in fish to
determine human health impacts. The Human Health Module multiplies the Cfish fillet total arsenic
concentration by four percent to estimate the inorganic arsenic concentration in fish.
E-2
-------
Appendix E — Human Health Module Methodology
Table E-l. Fish Consumed and Consumption Ratios of Fish at Trophic Levels 3 and 4
(Ft3 and Ft4)
Species
Ice l-'ishin^
l.iikes iind Ponds
Ki\crs iind Sirciims
Number of
l-'isli
( onsiimcd
Miiss
Consumed
(kii>
Number of
l-'isli
Consumed
Miiss
Consumed
(kii>
N ii in her of
l-isli
(oil sullied
Miiss
( oil slimed
-------
Appendix E — Human Health Module Methodology
Equation E-2
. __ ^fish fillet X CRfisij x Fggjj
ADD =
1,000 x BW
Where:
ADD
Daily dose of pollutant from fish ingestion
(mg per kg of body weight per day (mg/kg
bw-day)
Output from Equation E-2
Cfish fillet
=
Average fish fillet concentration ingested by
humans (mg/kg)
Output from Equation E-l
CRfish
=
Consumption rate of fish (g wet weight/day)
Cohort-specific value (see
Table E-3 and Table E-4)
Ffish
=
Fraction of fish intake from contaminated
source
Globally assigned value of 1
1,000
=
Conversion factor (grams per kilograms
(g/kg))
Conversion factor
BW
=
Body weight (kg)
Cohort-specific value (see
Table E-3)
Equation E-3 calculates the LADD, based on the ADD. Arsenic is the only carcinogenic
pollutant included in the EA. 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). The EPA assumed that the exposure durations (ED) for use in the LADD
calculation are equal to the length of time in that cohort range. The EPA selected an exposure
frequency of 350 days per year, assuming residents take an average of two weeks of vacation
away from their homes each year.
Equation E-4 calculates the non-cancer HQ, based on the ADD.
Equation E-5 calculates the LECR for inorganic arsenic, based on the LADD.
Equation E-3
ADD x ED x EF
LADD= ArT.
AT x 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
E-4
-------
Appendix E — Human Health Module Methodology
ED
Exposure duration for oral ingestion (yr)
Cohort-specific value
(assumed value)
(see Table E-3)
EF
=
Exposure frequency (days/yr)
Globally assigned value of
350
AT
=
Averaging time (yr)
Globally assigned value of 70
(U.S. EPA, 2011c)
365
=
Conversion factor (days/yr)
Equation E-4
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
=
Non-cancer oral reference dose (mg/kg bw-
day)
Pollutant-specific value
(see Table E-5)
Equation E-5
LECR = LADD x CSF
Where:
LECR
=
Lifetime excess cancer risk
Output from Equation E-5
LADD
=
Lifetime average daily dose (mg/kg bw-day)
Output from Equation E-3
CSF
=
Cancer slope factor (mg/kg bw-day)"1
Pollutant-specific value
(see Table E-5)
IRW Model: Human Health Module Inputs and Benchmark Values
For the EA and economic benefits analyses,4 the EPA focused on human exposure to
contaminated fish for recreational and subsistence fishers. Recreational fishers are non-
commercial, non-subsistence fishers and are more vulnerable to pollutant exposure by intake of
contaminated fish from a specific waterbody compared to the general population. Subsistence
fishers are individuals who consume fresh caught fish as a major food source. Intake rates for
subsistence fishers are generally higher than for the general population, and subsistence fishers
are more vulnerable to pollutant exposure by intake of contaminated fish from a specific
4 See the Benefit and Cost Analysis for Proposed Revisions to the Effluent Limitations Guidelines and Standards for
the Steam Electric Power Generating Point Source Category (BCA Report), Document No. EPA-821-R-19-009
(U.S. EPA, 2019b).
ADD
HQ= Rffl
E-5
-------
Appendix E — Human Health Module Methodology
waterbody compared to both recreational fishers and the general population. Because of the
focus of human exposure on a subset of the general population that more frequently consume
local fish, the EPA selected fish consumption rates from studies based on "consumer only" data.
Consumer-only fish consumption rates are the average intake rates across only those individuals
that consumed fish and shellfish during the survey time period. See the memorandum "Fish
Consumption Rates Used in the Environmental Assessment Human Health Module" for further
details (ERG, 2015).
The Human Health Module calculates annual-average daily doses of pollutants for recreational
and subsistence fishers and does not calculate the annual-average daily doses of pollutants for the
general population. In its economic benefits analysis (see the BCA Report), the EPA evaluates
impacts to a subset of the population living near the immediate and downstream receiving
waters.
Table 5-1 of the 2000 EPA document Methodology for Deriving Ambient Water Quality Criteria
for the Protection of Human Health provides protective fish intake rates based on the following
percentiles by fisher type: 1) general population and recreational fisher: 90th percentile of per
capita data and 2) subsistence fisher: 99th percentile of per capita data (U.S. EPA, 2000c). The
document does not provide guidance on which percentiles to use for consumer-only fish intake
rates. Therefore, the EPA used best professional judgment and used the mean of consumer-only
data to represent recreational fishers and the 95th percentile of consumer-only data to represent
subsistence fishers.
Table E-2. Assigned Values for Input Variables and Constants
Input
\ iiriiihlo or
Consiiini
Description
Assigned
Value
K;ilion;ilc/l);il;i Source
Ft3
Fraction of trophic level 3 fish intake
0.36
U.S. EPA, 2011c
Ft4
Fraction of trophic level 4 fish intake
0.64
U.S. EPA, 2011c
Ffish
Fraction of fish intake from
contaminated source
1
The EPA assumed that all fish consumed by the
cohort is from the contaminated surface water.
EF
Exposure frequency (days/yr)
350
The EPA assumed that the fisher (cohort) travels
away from home for 15 days per year and does
not eat fish from contaminated surface water
during that period.
AT
Averaging time (yr)
70
U.S. EPA, 2011c
E-6
-------
Appendix E — Human Health Module Methodology
Table E-3. Cohort-Specific Input Variables
Alio iiiid I'isli Consumption
Cohort ''
liod\ WoiiilU
Consumption
Usilc )h
Consumption
Usilc ik/cIsij )h
l'l\|)OMIIV
Dui'iilion (\c;ii s)
Child
Recreational
Fisher
1 to <2 years
11.4
1.60
18.2
1
2 to <3 years
13.8
1.60
22.1
1
3 to <6 years
18.6
1.30
24.2
3
6 to <11 years
31.8
1.10
35.0
5
11 to <16 years
56.8
0.660
37.5
5
16 to <21 years
71.6
0.660
47.3
5
Child
Subsistence
Fisher
1 to <2 years
11.4
4.90
55.9
1
2 to <3 years
13.8
4.90
67.6
1
3 to <6 years
18.6
3.60
67.0
3
6 to <11 years
31.8
2.90
92.2
5
11 to <16 years
56.8
1.70
96.6
5
16 to <21 years
71.6
1.70
122
5
Adult Recreational Fisher0
80
0.665
53.2
49
Adult Subsistence Fisher0
80
2.05
164
49
Sources: U.S. EPA, 2008b; U.S. EPA, 2011c.
Acronyms: g/day (grams per day); g/kg-day (grams per kilogram of body weight per day); kg (kilograms),
a - The child cohort age ranges correspond to the ranges provided in the 2008 Child-Specific Exposure Factors
Handbook (EFH) for body weights (U.S. EPA, 2008b).
b - The EPA determined consumption rates for child cohorts using data from Table 10-1 (Recommend Per Capita
and Consumer-Only Values for Fish Intake) for finfish consumption (U.S. EPA, 201 lc). The EPA used consumer-
only fish consumption rates: mean values for recreational fishers and 95th percentile values for subsistence fishers.
The EPA converted the listed consumption rate (g/kg-day) to g/day by multiplying by mean body weight for each
cohort as described in ERG (2015). Fish intake rates provided in U.S. EPA (201 lc) are recommended for the
consumer-only population; the selection of consumption rates for exposure assessment purposes may vary
depending on the exposure scenarios being evaluated.
c - Table 10-1 (U.S. EPA, 2011c) presented multiple adult groups. The EPA used the average fish consumption rate
for age groups "21 to <50 years" and "50+ years" to calculate a single adult cohort fish consumption rate.
E-7
-------
Appendix E — Human Health Module Methodology
Table E-4. Environmental Justice Analysis: Cohort-Specific Input Consumption Rate by Race Category
Fish Consumption ;nul Rsiee Csileiion Cohort
( Kim,.
( All siiies);l
( ciiisiiillption Rsile (( Kh.h). ii/(lsi\. In Cohort h
1 (o <2
Years
2 lo <3
Yesirs
3 lo <(>
Yesirs
(l lo <11
Yesirs
11 lo
Yesirs
Hi lo <21
Yesirs
Ariull
Recreational
Non-Hispanic White
0.67
7.64
9.25
12.5
21.3
38.1
48
53.6
Non-Hispanic Black
0.77
8.78
10.6
14.3
24.5
43.7
55.1
61.6
Mexican-American
0.93
10.6
12.8
17.3
29.6
52.8
66.6
74.4
Other Hispanic
0.82
9.35
11.3
15.3
26.1
46.6
58.7
65.6
Other, including Multiple Races
0.96
10.9
13.2
17.9
30.5
54.5
68.7
76.8
Subsistence
Non-Hispanic White
1.9
21.7
26.2
35.3
60.4
108
136
152
Non-Hispanic Black
2.1
23.9
29.0
39.1
66.8
119
150
168
Mexican-American
2.8
31.9
38.6
52.1
89.0
159
200
224
Other Hispanic 0
2.7
30.8
37.3
50.2
85.9
153
193
216
Other, including Multiple Races0
3.6
41.0
49.7
67.0
114
204
258
288
Source: U.S. EPA, 2011c.
Acronyms: CRf,sh (consumption rate); g/day (grams per day); g/kg-day (grams per kilogram body weight per day).
a - For recreational fishers, the EPA used the mean, consumer-only fish consumption rate for finfish (excludes shellfish). For subsistence fishers, the EPA used the 95th
percentile, consumer-only fish consumption rate for finfish (excludes shellfish). See Table 10-8 of U.S. EPA, 2011c.
b - Consumption rates provided as single value by race category (as g/kg-day). The EPA multiplied these values by cohort-specific body weights, as listed in Table E-3,
to calculate a cohort-specific consumption rate in g/day. Numbers presented as three significant digits,
c - Consumption rates for this race category are less statistically reliable due to the comparatively smaller data set.
E-8
-------
Appendix E — Human Health Module Methodology
Table E-5. Pollutant-Specific Benchmark Values
Polliiliini in lliiniiin lloiillh
llll|)ilCl Annonniik'iK
Oi iil Kl'l)
(SI
\oles '
Arsenic, inorganic
3.00 x 10"4
1.50
Oral RfD and CSF for drinking water
ingestion.
Cadmium, total
1.00 x 10"3
Oral RfD for food consumption.
Copper
1.00 x 10"2
Used the intermediate oral minimal risk level
(MRL) as the oral RfD (ATSDR, 2010b).
Lead, total
None available
Methylmercury
1.00 x 10"4
Oral RfD for fish consumption only.
Nickel, total
2.00 x 10"2
Oral RfD for soluble salts; used for food
consumption.
Selenium, total
5.00 x 10"3
Oral RfD for food consumption.
Thallium, total
1.00 x 10"5
Used value cited in U.S. EPA, 2010a for
thallium chloride as the oral RfD; used for
chronic oral exposure.
Zinc, total
3.00 x 101
Oral RfD for food consumption.
Acronyms: CSF (cancer slope factor); mg/kg-day (milligrams per kilogram body weight per day); RfD (reference
dose).
a - References include ATSDR (2010b) for copper; U.S. EPA (2010a) for thallium, and U.S. EPA (2019e) for all
other pollutants.
IRW Model: Human Health Module Limitations and Assumptions
The Human Health Module limitations and assumptions include the following:
• Cumulative Risks Across Exposure Pathways. The Human Health Module does not
consider cumulative risks across exposure pathways. For example, the module
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 module
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 discharges of the evaluated
wastestreams.
• Bioavailability and Speciation of Pollutants. The assumptions listed for the Wildlife
Module in Appendix D apply to pollutant concentrations modeled in fish and
therefore affect the human health impact assessment.
• Full Mixing Effects for Receiving Water. The assumptions listed for the Wildlife
Module in Appendix D apply to pollutant concentrations modeled in fish and
therefore affect the human health impact assessment.
E-9
-------
Appendix E — Human Health Module Methodology
• Multiple Pollutant Exposures. According to previous analyses and literature
reviewed (U.S. EPA, 2009d), people who ingest fish from impacted waters will be
exposed to multiple pollutants from the wastestreams evaluated. However, the
module evaluates each pollutant individually. Such an approach does not account for
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
benchmark values are based on the toxicity of individual pollutants, it is not possible
to examine these synergistic effects in this analysis. Based on this limitation, risks of
pollutants may be over- or underestimated.
• Sources of Consumed Fish. The Human Health Module assumes that all of the fish
consumed by recreational and subsistence fishers is caught from the immediate
receiving water, except during a two-week time period once per year. This
assumption potentially overestimates the annual-average daily dose of the pollutants
for these cohorts, particularly for recreational fishers. The proportion of fish eaten by
an individual from local surface waters will vary (e.g., consumption rate estimates in
studies might include seafood purchased from a grocery store and not locally caught).
• 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. The EPA used the most current data
regarding exposure assumptions, and these values represent the EPA's current
guidance on exposure data (U.S. EPA, 2008b; U.S. EPA, 2011c).
• Human Health Benchmark Values. Uncertainties generally associated with human
health benchmark values are discussed in detail in the EPA's Guidelines for
Carcinogen Risk Assessment (U.S. EPA, 2005c) and Integrated Risk Information
System (IRIS) (U.S. EPA, 2019e). IRIS defines the oral 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." While doses less than the
oral RfD are not likely to be associated with adverse health risks, it should not be
categorically concluded that all doses below the oral RfD are risk-free, particularly
for pollutants (e.g., arsenic and nickel) whose oral RfDs have not been established
with a high level of confidence. Additionally, oral 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, 2019e). 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 LADD used for the cancer risk assessment, the 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 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, the 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, 201 lc).
E-10
-------
Appendix F—Additional IRW Model Results
APPENDIX F
ADDITIONAL IRW MODEL RESULTS
This appendix presents pollutant loadings and additional model outputs for all pollutants
included in the Immediate Receiving Water (IRW) Model, specifically: arsenic, cadmium,
copper, lead, mercury, nickel, selenium, thallium, and zinc. Section 3 of the supplemental
environmental assessment report (Supplemental EA) and Appendices C, D, and E describe the
methodologies associated with the Water Quality Module, Wildlife Module, and Human Health
Module. This appendix presents additional results beyond those discussed in Section 4 of the
Supplemental EA and includes the following tables:
• Table F-l. Modeled IRWs Exceeding Benchmark Values for Any Pollutant under
Baseline and Four Regulatory Options
• Table F-2. Modeled IRWs Exceeding Arsenic Benchmark Values under Baseline and
Four Regulatory Options
• Table F-3. Modeled IRWs Exceeding Cadmium Benchmark Values under Baseline
and Four Regulatory Options
• Table F-4. Modeled IRWs Exceeding Copper Benchmark Values under Baseline and
Four Regulatory Options
• Table F-5. Modeled IRWs Exceeding Lead Benchmark Values under Baseline and
Four Regulatory Options
• Table F-6. Modeled IRWs Exceeding Mercury Benchmark Values under Baseline
and Four Regulatory Options
• Table F-7. Modeled IRWs Exceeding Nickel Benchmark Values under Baseline and
Four Regulatory Options
• Table F-8. Modeled IRWs Exceeding Selenium Benchmark Values under Baseline
and Four Regulatory Options
• Table F-9. Modeled IRWs Exceeding Thallium Benchmark Values under Baseline
and Four Regulatory Options
• Table F-10. Modeled IRWs Exceeding Zinc Benchmark Values under Baseline and
Four Regulatory Options
• Table F-l 1. Modeled IRWs Exceeding Non-Cancer Oral Reference Dose Values
under Baseline and Four Regulatory Options, by Race Category
• Table F-12. Modeled IRWs with Lifetime Excess Cancer Risk for Inorganic Arsenic
Exceeding One-in-a-Million under Baseline and Four Regulatory Options, by Race
Category
F-l
-------
Appendix F—Additional IRW Model Results
Table F-l. Modeled IRWs Exceeding Benchmark Values for Any Pollutant under
Baseline and Four Regulatory Options
Polliiliini l.oiidiniis li;isis
Indiisln I'nlliiiiini l.tiiidin^s ilh/j n ¦'
liiiseline
Option 1
Option 2
Option 3
Option 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
4,560
63,500
27,900
17,200
14,700
l.\ iilu;ilion lienehm;irk
Modeled Number of IRWs r.xceedinii lieiiehiiiiii'k Value"1"1'
liiiseline
Option 1
Option 2
Option 3
Option 4
Water Quality Results
Freshwater Acute NRWQC
0
2
0
0
0
Freshwater Chronic NRWQC
0
10
3
2
2
Human Health Water and Organism NRWQC
9
20
17
16
13
Human Health Organism Only NRWQC
4
9
8
7
7
Drinking Water MCL
1
3
3
2
1
Wildlife Results
Sediment TEC
2
20
10
7
6
Fish Ingestion NEHC for Minks
0
10
4
2
2
Fish Ingestion NEHC for Eagles
1
11
7
5
3
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
2
8
7
6
5
T4 Fish Tissue Concentration Screening Value
(Subsistence)
6
18
14
11
9
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
6
15
12
10
8
Oral RfD for Child (Subsistence)
9
23
19
14
11
Oral RfD for Adult (Recreational)
4
10
7
7
7
Oral RfD for Adult (Subsistence)
6
16
12
10
8
Human Health Results - Cancer
LECR for Child (Recreational)
0
0
1
0
0
LECR for Child (Subsistence)
0
0
1
0
0
LECR for Adult (Recreational)
0
1
2
1
1
LECR for Adult (Subsistence)
0
1
2
1
1
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures.
a - Values represent the industry loadings and the IRW Model outputs for the following nine evaluated
pollutants: arsenic, cadmium, copper, lead, mercury, nickel, selenium, thallium, and zinc,
b - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-2
-------
Appendix F—Additional IRW Model Results
Table F-2. Modeled IRWs Exceeding Arsenic Benchmark Values under Baseline and
Four Regulatory Options
Polliiliini l.oiidiniis li;isis
ludiisln Arsenic Loadings (Ih/j n
liiiseliue
Option 1
Opliou 2
Opliou 3
Opliou 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
407
503
1,010
433
182
11 \ iiliiiilion lieuchm;irk
Modeled Number of IRW s l-'.\eeediu;i Arsenic licnchnuirk
Value 11
ISiiseline
Opliou 1
Opliou 2
Opliou 3
Opliou 4
Water Quality Results
Freshwater Acute NRWQC a
0
0
0
0
0
Freshwater Chronic NRWQC 11
0
0
0
0
0
Human Health Water and Organism NRWQC b
9
20
17
16
13
Human Health Organism Only NRWQC b
4
9
8
7
7
Drinking Water MCL
0
1
2
1
1
Wildlife Results
Sediment TEC
0
0
1
0
0
Fish Ingestion NEHC for Minks
0
0
0
0
0
Fish Ingestion NEHC for Eagles
0
0
0
0
0
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)bc
0
0
0
0
0
T4 Fish Tissue Concentration Screening Value
(Subsistence)bc
0
0
1
0
0
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)b
0
0
0
0
0
Oral RfD for Child (Subsistence)b
0
0
0
0
0
Oral RfD for Adult (Recreational)b
0
0
0
0
0
Oral RfD for Adult (Subsistence)b
0
0
0
0
0
Human Health Results - Cancer
LECR for Child (Recreational)b
0
0
1
0
0
LECR for Child (Subsistence)b
0
0
1
0
0
LECR for Adult (Recreational)b
0
1
2
1
1
LECR for Adult (Subsistence)b
0
1
2
1
1
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total arsenic
concentration, unless otherwise stated.
a - Benchmark value is based on dissolved arsenic.
b - Benchmark value is based on inorganic arsenic.
c - Values represent number of immediate receiving waters exceeding either the noncarcinogenic or carcinogenic
screening values.
d - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-3
-------
Appendix F—Additional IRW Model Results
Table F-3. Modeled IRWs Exceeding Cadmium Benchmark Values under Baseline and
Four Regulatory Options
Polliiliini l.oiidiniis li;isis
Indiisln ( ;i«l in in in l.oiuliniis tlh/jr)
liiisoliiic
Option 1
Option 2
Option 3
Option 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
302
309
318
259
78.5
l'l\ iiliiiilion lioiichiiiiii k
Modeled Number of IRW s l.xcocdinii ( iidiniuni
lieiichiiiiii'k Value''
liiiseline
Option 1
Option 2
Option 3
Option 4
Water Quality Results
Freshwater Acute NRWQC a
0
0
0
0
0
Freshwater Chronic NRWQC 11
0
0
1
0
0
Human Health Water and Organism NRWQC
b
b
b
b
b
Human Health Organism Only NRWQC
b
b
b
b
b
Drinking Water MCL
0
0
1
0
0
Wildlife Results
Sediment TEC
1
1
2
1
0
Fish Ingestion NEHC for Minks
0
0
0
0
0
Fish Ingestion NEHC for Eagles
0
0
0
0
0
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
0
0
0
0
0
T4 Fish Tissue Concentration Screening Value
(Subsistence)
0
0
1
0
0
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
0
0
0
0
0
Oral RfD for Child (Subsistence)
0
0
1
0
0
Oral RfD for Adult (Recreational)
0
0
0
0
0
Oral RfD for Adult (Subsistence)
0
0
1
0
0
Human Health Results - Cancer
LECR for Child (Recreational)
b
b
b
b
b
LECR for Child (Subsistence)
b
b
b
b
b
LECR for Adult (Recreational)
b
b
b
b
b
LECR for Adult (Subsistence)
b
b
b
b
b
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total
cadmium concentration, unless otherwise stated,
a - Benchmark value is based on dissolved cadmium.
b - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
c - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-4
-------
Appendix F—Additional IRW Model Results
Table F-4. Modeled IRWs Exceeding Copper Benchmark Values under Baseline and
Four Regulatory Options
Polluliint l.oiidiniis li;isis
Indusln ( tipper loiidiniis (Ih/jr)
liiiseline
Option 1
Option 2
Option 3
Option 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
264
304
506
259
96.9
11 \ iiliiiilion lienehm;irk
Modeled Number of IRW s l-Aceediug ( upper lieuehiiiiirk
Value'
liiiseliue
Option 1
Option 2
Option 3
Option 4
Water Quality Results
Freshwater Acute NRWQC a
0
0
0
0
0
Freshwater Chronic NRWQC 11
0
0
1
0
0
Human Health Water and Organism NRWQC
0
0
0
0
0
Human Health Organism Only NRWQC
b
b
b
b
b
Drinking Water MCL
0
0
0
0
0
Wildlife Results
Sediment TEC
0
0
1
0
0
Fish Ingestion NEHC for Minks
0
0
0
0
0
Fish Ingestion NEHC for Eagles
0
0
0
0
0
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
b
b
b
b
b
T4 Fish Tissue Concentration Screening Value
(Subsistence)
b
b
b
b
b
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
0
0
0
0
0
Oral RfD for Child (Subsistence)
0
0
0
0
0
Oral RfD for Adult (Recreational)
0
0
0
0
0
Oral RfD for Adult (Subsistence)
0
0
0
0
0
Human Health Results - Cancer
LECR for Child (Recreational)
b
b
b
b
b
LECR for Child (Subsistence)
b
b
b
b
b
LECR for Adult (Recreational)
b
b
b
b
b
LECR for Adult (Subsistence)
b
b
b
b
b
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total copper
concentration, unless otherwise stated,
a - Benchmark value is based on dissolved copper.
b - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
c - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-5
-------
Appendix F—Additional IRW Model Results
Table F-5. Modeled IRWs Exceeding Lead Benchmark Values under Baseline and Four
Regulatory Options
Polliiliini l.oiidiniis li;isis
ludiisln l.e;id l.oiidiniis (Ih/j n
liiiseliue
Option 1
Opliou 2
Opliou 3
Opliou 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
240
347
933
306
161
11 \ iiliiiilion lieuehm;irk
Modeled Number of IRW s r.\eeediu*i l.e;id lieuehm;irk
Value'
liiiseliue
Opliou 1
Opliou 2
Opliou 3
Opliou 4
Water Quality Results
Freshwater Acute NRWQC a
0
0
0
0
0
Freshwater Chronic NRWQC 11
0
0
1
0
0
Human Health Water and Organism NRWQC
b
b
b
b
b
Human Health Organism Only NRWQC
b
b
b
b
b
Drinking Water MCL
0
1
2
1
1
Wildlife Results
Sediment TEC
0
0
1
0
0
Fish Ingestion NEHC for Minks
0
0
0
0
0
Fish Ingestion NEHC for Eagles
0
0
0
0
0
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
b
b
b
b
b
T4 Fish Tissue Concentration Screening Value
(Subsistence)
b
b
b
b
b
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
b
b
b
b
b
Oral RfD for Child (Subsistence)
b
b
b
b
b
Oral RfD for Adult (Recreational)
b
b
b
b
b
Oral RfD for Adult (Subsistence)
b
b
b
b
b
Human Health Results - Cancer
LECR for Child (Recreational)
b
b
b
b
b
LECR for Child (Subsistence)
b
b
b
b
b
LECR for Adult (Recreational)
b
b
b
b
b
LECR for Adult (Subsistence)
b
b
b
b
b
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total lead
concentration, unless otherwise stated,
a - Benchmark value is based on dissolved lead.
b - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
c - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-6
-------
Appendix F—Additional IRW Model Results
Table F-6. Modeled IRWs Exceeding Mercury Benchmark Values under Baseline and
Four Regulatory Options
Polluliint Loadings li;isis
InduMn Mereun Loadings ilh/jr)
liiiseline
Option 1
Option 2
Option 3
Option 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
4.50
11.1
12.8
6.13
3.96
11 \ iiliiiilion lienehm;irk
Modeled Number of IRWs K\eeedin*i Mereun l$enehm;irk
Value 1
liiiseliue
Option 1
Option 2
Option 3
Option 4
Water Quality Results
Freshwater Acute NRWQC a
0
0
0
0
0
Freshwater Chronic NRWQC 11
0
0
0
0
0
Human Health Water and Organism NRWQC
b
b
b
b
b
Human Health Organism Only NRWQC
b
b
b
b
b
Drinking Water MCL 0
0
0
0
0
0
Wildlife Results
Sediment TEC
0
5
4
3
2
Fish Ingestion NEHC for Minks d
0
3
3
2
2
Fish Ingestion NEHC for Eagles d
1
6
6
5
3
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational) d
2
7
7
6
5
T4 Fish Tissue Concentration Screening Value
(Subsistence) d
6
16
14
11
9
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational) d e
5
11
10
9
8
Oral RfD for Child (Subsistence) d e
6
19
17
14
11
Oral RfD for Adult (Recreational) d e
3
10
7
7
7
Oral RfD for Adult (Subsistence) d e
6
14
12
10
8
Human Health Results - Cancer
LECR for Child (Recreational)
b
b
b
b
b
LECR for Child (Subsistence)
b
b
b
b
b
LECR for Adult (Recreational)
b
b
b
b
b
LECR for Adult (Subsistence)
b
b
b
b
b
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total mercury
concentration, unless otherwise stated,
a - Benchmark value is based on dissolved mercury.
b - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
c - Benchmark value is based on inorganic mercury.
d - Comparison to benchmark value is based on modeled methylmercury concentration in fish tissue,
e - Benchmark value is based on methylmercury.
f - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving waters
and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-7
-------
Appendix F—Additional IRW Model Results
Table F-7. Modeled IRWs Exceeding Nickel Benchmark Values under Baseline and Four
Regulatory Options
Polliiliini l.oiidiniis li;isis
ludusln Nickel l.o;i(lin;iN (ll)/\ r)
liiiscliuc
Option 1
Opliou 2
Opliou 3
Opliou 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
554
909
1,769
695
423
11 \ iiliiiilion licuchm;irk
Modeled Number of IRWs Mxeeediii^ Nickel lieiichniiii'k
Value'
liiiseliue
Opliou 1
Opliou 2
Opliou 3
Opliou 4
Water Quality Results
Freshwater Acute NRWQC a
0
0
0
0
0
Freshwater Chronic NRWQC 11
0
0
1
0
0
Human Health Water and Organism NRWQC
0
0
0
0
0
Human Health Organism Only NRWQC
0
0
0
0
0
Drinking Water MCL
b
b
b
b
b
Wildlife Results
Sediment TEC
0
3
4
3
2
Fish Ingestion NEHC for Minks
0
0
0
0
0
Fish Ingestion NEHC for Eagles
0
0
0
0
0
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
b
b
b
b
b
T4 Fish Tissue Concentration Screening Value
(Subsistence)
b
b
b
b
b
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
0
0
0
0
0
Oral RfD for Child (Subsistence)
0
0
0
0
0
Oral RfD for Adult (Recreational)
0
0
0
0
0
Oral RfD for Adult (Subsistence)
0
0
0
0
0
Human Health Results - Cancer
LECR for Child (Recreational)
b
b
b
b
b
LECR for Child (Subsistence)
b
b
b
b
b
LECR for Adult (Recreational)
b
b
b
b
b
LECR for Adult (Subsistence)
b
b
b
b
b
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total nickel
concentration, unless otherwise stated,
a - Benchmark value is based on dissolved nickel.
b - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
c - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-8
-------
Appendix F—Additional IRW Model Results
Table F-8. Modeled IRWs Exceeding Selenium Benchmark Values under Baseline and
Four Regulatory Options
Polliiliini l.oiidiniis li;isis
Indiisln Selenium 1.(Hidings (IhAn
|};iseline
Option 1
Option 2
Option 3
Option 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
547
58,500
18,900
13,000
12,800
11 \ iiliiiilion lionchiiiiii'k
Modeled Number of IRW s l.xeeedinii Selenium l}enehm;irk
Value h
I5;iseli lie
Option 1
Option 2
Option 3
Option 4
Water Quality Results
Freshwater Acute NRWQC
0
2
0
0
0
Freshwater Chronic NRWQC
0
10
3
2
2
Human Health Water and Organism NRWQC
0
1
0
0
0
Human Health Organism Only NRWQC
0
0
0
0
0
Drinking Water MCL
0
2
1
0
0
Wildlife Results
Sediment TEC
2
20
10
7
6
Fish Ingestion NEHC for Minks
0
9
3
1
1
Fish Ingestion NEHC for Eagles
0
9
3
1
1
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
0
5
2
1
1
T4 Fish Tissue Concentration Screening Value
(Subsistence)
0
12
6
4
2
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
0
9
3
1
1
Oral RfD for Child (Subsistence)
2
16
9
5
3
Oral RfD for Adult (Recreational)
0
6
2
1
1
Oral RfD for Adult (Subsistence)
0
10
4
2
1
Human Health Results - Cancer
LECR for Child (Recreational)
a
a
a
a
a
LECR for Child (Subsistence)
a
a
a
a
a
LECR for Adult (Recreational)
a
a
a
a
a
LECR for Adult (Subsistence)
a
a
a
a
a
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total
selenium concentration, unless otherwise stated.
a - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
b - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-9
-------
Appendix F—Additional IRW Model Results
Table F-9. Modeled IRWs Exceeding Thallium Benchmark Values under Baseline and
Four Regulatory Options
I'olliiiiini (.outlines linsis
Indiisln Thallium Loadings ilh/jr)
Baseline
Option 1
Option 2
Option 3
Option 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
675
687
674
569
146
11 \ iiliiiilion lienehm;irk
Modeled Number of IRW s l-Aceediug Thallium Benehmark
Value h
Baseline
Option 1
Option 2
Option 3
Option 4
Water Quality Results
Freshwater Acute NRWQC
a
a
a
a
a
Freshwater Chronic NRWQC
a
a
a
a
a
Human Health Water and Organism NRWQC
4
5
4
3
l
Human Health Organism Only NRWQC
3
4
4
3
l
Drinking Water MCL
1
1
2
1
0
Wildlife Results
Sediment TEC
a
a
a
a
a
Fish Ingestion NEHC for Minks
a
a
a
a
a
Fish Ingestion NEHC for Eagles
a
a
a
a
a
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
a
a
a
a
a
T4 Fish Tissue Concentration Screening Value
(Subsistence)
a
a
a
a
a
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
6
9
8
7
4
Oral RfD for Child (Subsistence)
9
14
11
10
7
Oral RfD for Adult (Recreational)
4
6
5
4
2
Oral RfD for Adult (Subsistence)
6
10
8
8
6
Human Health Results - Cancer
LECR for Child (Recreational)
a
a
a
a
a
LECR for Child (Subsistence)
a
a
a
a
a
LECR for Adult (Recreational)
a
a
a
a
a
LECR for Adult (Subsistence)
a
a
a
a
a
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total thallium
concentration, unless otherwise stated.
a - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
b - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-10
-------
Appendix F—Additional IRW Model Results
Table F-10. Modeled IRWs Exceeding Zinc Benchmark Values under Baseline and Four
Regulatory Options
Polliiliini l.oiidiniis li;isis
Indiisln Zinc l.o;i(liniis tlh/\r)
|};isclinc
Option 1
Option 2
Option 3
Option 4
Mass Loadings from all 112 Coal-Fired Power
Plants in Pollutant Loadings Analysis
1,560
1,910
3,740
1,670
813
l'l\ iiliiiilion lioiichiiiiii k
Modeled Number of IRW s l.xcccdinii Zinc Iknchniiirk
\ idue'
liiiseline
Option 1
Option 2
Option 3
Option 4
Water Quality Results
Freshwater Acute NRWQC a
0
0
0
0
0
Freshwater Chronic NRWQC 11
0
0
0
0
0
Human Health Water and Organism NRWQC
0
0
0
0
0
Human Health Organism Only NRWQC
0
0
0
0
0
Drinking Water MCL
0
0
0
0
0
Wildlife Results
Sediment TEC
0
0
1
0
0
Fish Ingestion NEHC for Minks
0
0
0
0
0
Fish Ingestion NEHC for Eagles
0
0
0
0
0
Human Health Results - Fish Consumption Advisories
T4 Fish Tissue Concentration Screening Value
(Recreational)
b
b
b
b
b
T4 Fish Tissue Concentration Screening Value
(Subsistence)
b
b
b
b
b
Human Health Results - Non-Cancer
Oral RfD for Child (Recreational)
0
0
0
0
0
Oral RfD for Child (Subsistence)
0
0
1
0
0
Oral RfD for Adult (Recreational)
0
0
0
0
0
Oral RfD for Adult (Subsistence)
0
0
0
0
0
Human Health Results - Cancer
LECR for Child (Recreational)
b
b
b
b
b
LECR for Child (Subsistence)
b
b
b
b
b
LECR for Adult (Recreational)
b
b
b
b
b
LECR for Adult (Subsistence)
b
b
b
b
b
Source: ERG, 2019e; ERG, 2019i.
Acronyms: IRW (immediate receiving water); lb/yr (pounds per year); LECR (lifetime excess cancer risk); MCL
(maximum contaminant level); NEHC (no effect hazard concentration); NRWQC (National Recommended Water
Quality Criteria); RfD (reference dose); TEC (threshold effect concentration); T4 (trophic level 4).
Note: Pollutant loadings are rounded to three significant figures. All benchmark values are based on total zinc
concentration, unless otherwise stated,
a - Benchmark value is based on dissolved zinc.
b - A benchmark value is not yet established for this pollutant or was not included in the EPA's analyses,
c - The IRW Model, which excludes the Great Lakes and estuaries, analyzes 106 total immediate receiving
waters and loadings from 105 coal-fired power plants (some of which discharge to multiple receiving waters).
F-ll
-------
Appendix F—Additional IRW Model Results
Table F-ll. Modeled IRWs Exceeding Non-Cancer Oral Reference Dose Values under Baseline and Four Regulatory
Options, by Race Category
Aiie iiiid l \ po «r
l-'isli Consumption
(oIlOI'l
R;ioo C;ito;;or\
Modeled N u in her IRW s Uxooodin" \on-C;inoor ()r;il KID ol° N;imod Polliiliint
Tolnl Arsenic
C ;i«l111 ill 111
li.i so-
li no
Option
1
Option
t
Option
3
Option
4
li;i so-
li no
Option
1
Option
->
Option
3
Option
4
Recreational
(All age cohorts)
\ on-1 libpamc White
u
u
u
u
0
u
u
0
0
0
Non-Hispanic Black
0
0
0
0
0
0
0
0
0
0
Mexican-American
0
0
0
0
0
0
0
0
0
0
Other Hispanic
0
0
0
0
0
0
0
0
0
0
Other, incl. Multiple Races
0
0
0
0
0
0
0
0
0
0
Subsistence
(All age cohorts)
Non-Hispanic White
0
0
0
0
0
0
0
1
0
0
Non-Hispanic Black
0
0
0
0
0
0
0
1
0
0
Mexican-American
0
0
0
0
0
0
0
1
0
0
Other Hispanic
0
0
0
0
0
0
0
1
0
0
Other, incl. Multiple Races
0
0
0
0
0
0
0
1
0
0
Ago iiiid Tjpo ol'
l isli ( onsiimplion
Cohort
R;ioo (
Copper
Morcun cis Mctlnlmcrcim)
I5;i so-
li iio
Option
1
Option
t
Option
3
Option
4
li;i so-
li no
Option
1
Option
->
Option
3
Option
4
Recreational
(All age cohorts)
Non-Hispanic White
0
0
0
0
0
3
10
7
7
7
Non-Hispanic Black
0
0
0
0
0
3
10
7
7
7
Mexican-American
0
0
0
0
0
3
11
8
8
8
Other Hispanic
0
0
0
0
0
3
10
7
7
7
Other, incl. Multiple Races
0
0
0
0
0
3
11
8
8
8
Subsistence
(All age cohorts)
Non-Hispanic White
0
0
0
0
0
5
14
11
10
8
Non-Hispanic Black
0
0
0
0
0
6
14
12
10
8
Mexican-American
0
0
0
0
0
6
16
14
11
9
Other Hispanic
0
0
0
0
0
6
16
14
11
9
Other, incl. Multiple Races
0
0
0
0
0
6
17
15
12
10
F-12
-------
Appendix F—Additional IRW Model Results
Table F-ll. Modeled IRWs Exceeding Non-Cancer Oral Reference Dose Values under Baseline and Four Regulatory
Options, by Race Category
Alio iiiul Tjpo ol'
l-'isli Consumption
Cohort
R;ioo ( ;itoiior\
Nnnihor IRWs llxooodinji \on-( ;inoor Orsil KID of N;imod Polliiliint
\iokol
Selenium
I5ii so-
li lie
Option
1
Option
2
Option
3
Option
4
I5;i so-
li no
Option
1
Option
2
Option
3
Option
4
Recreational
(All age cohorts)
\oii-l li^pame While
0
0
0
0
0
0
0
:
1
1
Non-Hispanic Black
0
0
0
0
0
0
6
2
1
1
Mexican-American
0
0
0
0
0
0
6
2
1
1
Other Hispanic
0
0
0
0
0
0
6
2
1
1
Other, incl. Multiple Races
0
0
0
0
0
0
6
2
1
1
Subsistence
(All age cohorts)
Non-Hispanic White
0
0
0
0
0
0
10
4
2
1
Non-Hispanic Black
0
0
0
0
0
0
10
4
2
1
Mexican-American
0
0
0
0
0
0
12
6
4
2
Other Hispanic
0
0
0
0
0
0
12
6
4
2
Other, incl. Multiple Races
0
0
0
0
0
1
12
6
4
2
Ago iiml Tjpo of
l-'isli ( onsiimption
Cohort
Usico (
1 hiilliiiin
Zinc
liii so-
li no
Option
1
Option
2
Option
3
Option
4
I5;i so-
li no
Option
1
Option
¦>
Option
3
Option
4
Recreational
(All age cohorts)
Non-Hispanic White
4
6
5
4
2
0
0
0
0
0
Non-Hispanic Black
4
6
5
4
2
0
0
0
0
0
Mexican-American
5
7
6
5
2
0
0
0
0
0
Other Hispanic
4
6
5
4
2
0
0
0
0
0
Other, incl. Multiple Races
5
7
6
5
2
0
0
0
0
0
Subsistence
(All age cohorts)
Non-Hispanic White
6
10
8
8
5
0
0
0
0
0
Non-Hispanic Black
6
10
8
8
6
0
0
0
0
0
Mexican-American
6
11
9
9
7
0
0
0
0
0
Other Hispanic
6
11
9
9
7
0
0
0
0
0
Other, incl. Multiple Races
8
14
10
10
7
0
0
1
0
0
Source: ERG, 2019i.
Acronyms: IRW (immediate receiving water); RfD (reference dose).
F-13
-------
Appendix F—Additional IRW Model Results
Table F-12. Modeled IRWs with Lifetime Excess Cancer Risk for Inorganic Arsenic Exceeding One-in-a-Million under
Baseline and Four Regulatory Options, by Race Category
Age iiml T\pe of l-'isli
U.ice (
Modeled \umher ol" IRWs r.\ceedin» I.I.CR
( oiiMimplion Cohort
Biiseliue
Option 1
Option 2
Option 3
Option 4
Recreational
Non-Hispanic White
0
1
2
1
1
(All age cohorts)
Non-Hispanic Black
0
1
2
1
1
Mexican-American
0
1
2
1
1
Other Hispanic
0
1
2
1
1
Other, including Multiple Races
0
1
2
1
1
Subsistence
Non-Hispanic White
0
1
2
1
1
(All age cohorts)
Non-Hispanic Black
0
1
2
1
1
Mexican-American
0
1
2
1
1
Other Hispanic
0
1
2
1
1
Other, including Multiple Races
0
2
3
2
1
Source: ERG, 2019i.
Acronyms: IRW (immediate receiving water); LECR (lifetime excess cancer risk).
F-14
------- |