Updated October 1, 2020
Overview of the Steam Electric Power Generator Effluent
Limitation Guidelines and Standards
Overview
 Best Practicable Control Technology Currently
The Clean Water Act (CWA) directs the Environmental
Available (BPT) is based on the average of the best
Protection Agency (EPA) to regulate the discharge of
existing performance of plants within the industry or
pollutants into waters of the United States. Such discharges
subcategory. In selecting BPT, EPA considers factors
are prohibited without a permit. Thus, industrial dischargers
including the cost of applying the control technology in
and others must obtain permits from states or EPA that set
relation to the effluent reduction benefits, equipment
limits on pollutants in their effluent. To guide the limits set
and facility age, and processes employed.
in permits for industrial dischargers, EPA issues Effluent
Limitation Guidelines and standards (ELGs)—technology-
 Best Available Technology Economically Achievable
based standards—for categories of industrial dischargers.
(BAT) generally represents the best existing
Since 1972, EPA has promulgated ELGs for 59 industrial
performance in the industrial category or subcategory.
categories, including the steam electric power industry—
Factors considered include the cost of achieving effluent
which covers power plants that use nuclear or fossil fuels to
reductions and processes employed.
generate steam used to produce electricity.
 New Source Performance Standards (NSPS) reflect the
In November 2015, EPA published revised ELGs (80
reductions achievable based on the best available
Federal Register 67838) for the steam electric power
demonstrated control technology. EPA is directed to
industry to replace rules issued in 1982. EPA determined
take into consideration the cost of achieving the effluent
that new ELGs were necessary to reflect changes in the
reduction and any non-water-quality environmental
industry. For example, technology improvements since
impacts and energy requirements.
1982, particularly at coal-fired power plants, reduced
hazardous air emissions but increased discharges of other
 Pretreatment Standards for Existing Sources (PSES) are
pollutants, primarily heavy metals, to surface waters. EPA
designed to control the discharge of pollutants that pass
promulgated the 2015 rule to address those water quality
through, interfere with, or are otherwise incompatible
impacts by establishing new or additional requirements for
with the operation of POTWs. PSES standards are
six wastestreams from steam electric power plants. In
analogous to BAT for direct dischargers.
September 2017, EPA finalized a rule postponing
compliance deadlines for two wastestreams to allow the
 Pretreatment Standards for New Sources (PSNS) are
agency time to revise the limits set in the 2015 rule. In
designed for the same purpose as PSES. EPA considers
November 2019, EPA proposed revisions to the 2015 final
the same factors in promulgating PSNS as it does in
rule for those two wastestreams. On August 31, 2020, EPA
promulgating NSPS.
finalized the rule, the “Steam Electric Reconsideration
Rule” (see “Current Status”).
CWA Section 304(m) directs EPA to annually review
existing ELGs to determine whether revisions are
Background and the 2015 Rule
appropriate. During its 2005 review, EPA identified the
ELGs are national regulations for industrial wastewater
steam electric power industry ELGs for possible revision
discharges that set technology-based numeric limits for
based in part on data showing that the industry ranked high
specific pollutants. For point sources that introduce
in discharges of toxic and nonconventional pollutants. EPA
pollutants directly into U.S. waters —“direct dischargers”—
initiated a study, completed in 2009, which found that the
states or EPA incorporate the limits set in ELGs into
1982 regulations did not adequately address the pollutants
National Pollutant Discharge Elimination System permits.
being discharged and had not kept pace with changes in the
For sources that discharge to publicly owned treatment
industry over the prior several decades. The study focused
works (POTWs)—“indirect dischargers”—EPA
primarily on coal ash handling operations and flue gas
promulgates pretreatment standards that are enforced by
desulfurization (FGD) systems (i.e., scrubbers) used at coal-
POTWs and federal and state authorities.
fired power plants to control air pollution. While scrubbers
reduce pollutant emissions into the air, some create a
The CWA requires industrial dischargers to achieve
significant liquid wastestream. The study further noted that
specified levels of pollution control based on whether a
pollutants in coal combustion wastewater at some plants
discharger is direct or indirect, a new or existing source,
have potential to degrade water quality when discharged or
and the category of pollutant discharged. The levels of
leached into groundwater and surface waters.
control pertinent to the 2015 rule are as follows:
In 2009, environmental groups sued EPA to compel the
agency to commit to a schedule for issuing revised ELGs
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link to page 2 Overview of the Steam Electric Pow er Generator Effluent Limitation Guidelines and Standards
for this industry. Pursuant to a consent decree, EPA
by not requiring more stringent controls on discharges of
promulgated a final rule in 2015. The 2015 rule includes
bromide. In March and April 2017, EPA received petitions
BAT and PSES requirements for existing sources and NSPS
for administrative reconsideration of the rule. According to
and PSNS requirements for new sources for six
EPA, the petitions raised “wide-ranging and sweeping
wastestreams (Table 1). It also maintains BPT requirements
objections to the rule” and included new data the agency
from the 1982 regulations for total suspended solids (TSS)
wanted to review. In April 2017, the Administrator
and oil and grease.
announced his decision to reconsider the rule. The Fifth
Circuit granted EPA’s request to sever and hold portions of
Table 1. Pollutant Discharge Limitations and Technology Basis
the case in abeyance while EPA reconsidered the rule.
for 2015 Steam Electric Power Generator ELGs
Existing Sources
New Sources
In September 2017, EPA published a final rule postponing
Wastestreams
(BAT and PSES)
(NSPS and PSNS)
the earliest compliance dates for BAT and PSES
requirements for two wastestreams—FGD wastewater and
Flue Gas
Numeric limitations on
Numeric limitations on
BA transport water—for a two-year period. EPA stated its
Desulfurization
arsenic, mercury,
arsenic, mercury,
intention to conduct a new rulemaking regarding the
(FGD) Wastewater
selenium, and nitrate/
selenium, and total
appropriate technology bases and limitations for those
nitrite as nitrogen
dissolved solids (TDS)
requirements “in light of new information not contained in


the record for the 2015 rule and the inherent discretion the
Chemical precipitation
Evaporation control
agency has to reconsider past policy decisions consistent
with the CWA and other applicable law.”
+ biological treatment
technology
EPA also stated
that it did not intend to revise requirements for the other
Fly Ash Transport
Zero discharge of
Zero discharge of
wastestreams covered by the 2015 rule and, as such, did not
Water
pol utants
pol utants
change their associated compliance dates.


Dry handling control
Dry handling control
In November 2019, EPA proposed a rule to revise the ELGs
technology
technology
applicable to FGD wastewater and BA transport water,
which it finalized on August 31, 2020. The 2020 rule
Bottom Ash (BA)
Zero discharge of
Zero discharge of
changes the technology basis for treatment of the two
Transport Water
pol utants
pol utants
wastestreams. EPA concluded that more affordable


technologies capable of removing similar pollutant amounts
Dry handling or closed
Dry handling or closed
became available since 2015. The 2020 rule establishes new
loop control
loop control
subcategories and varying requirements for high flow
technology
technology
facilities, low utilization units, and units retiring by 2028.
Flue Gas Mercury
Zero discharge of
Zero discharge of
FGD wastewater: FGD wastewater dischargers that do not
Control
pol utants
pol utants
fall into any of the new subcategories have numeric
Wastewater


limitations under the 2020 rule that are less stringent for
Dry handling control
Dry handling control
arsenic and selenium and more stringent for mercury and
technology
technology
nitrate/nitrite compared to the 2015 rule. Numeric
limitations for high flow facilities and low utilization
Gasification
Numeric limitations on
Numeric limitations on
boilers are removed for selenium or nitrate/nitrite and
Wastewater
arsenic, mercury,
arsenic, mercury,
remain unchanged from the 2015 rule for arsenic and
selenium, and TDS
selenium, and TDS
mercury. Boilers retiring by 2028 are required only to meet


TSS limitations. The 2020 rule retains the voluntary
Evaporation control
Evaporation control
incentives program for direct FGD wastewater dischargers
technology
technology
established in the 2015 rule, which gives plants more time
to implement new BAT requirements if they adopt
Combustion
Equal to BPT limitation
Numeric limitations on
additional process changes and controls that achieve more
Residual Leachate
for TSS
arsenic and mercury
stringent limitations. The 2020 rule’s limitations are less


stringent for arsenic, selenium, and TDS and more stringent
Impoundment control
Chemical precipitation
for mercury compared to the 2015 rule. The 2020 rule adds
technology
control technology
limitations for bromide and nitrate/nitrite. It also extends
Source: EPA, 80 Federal Register 67838-67903, November 3, 2015.
the timeline for the incentives program by five years.
Current Status
BA transport water: While the 2015 rule established a zero
discharge standard for BA transport water, the 2020 rule
Various stakeholders filed judicial petitions for review of
would establish a not-to-exceed 10 percent volumetric
the 2015 rule, which were consolidated in the U.S. Court of
purge limitation. For low utilization boilers, the 2020 rule
Appeals for the Fifth Circuit (Southwestern Elec. Power
requires facilities to implement best management practice
Co. v. EPA, 5th Cir., 15-60821, filed November 20, 2015).
plans and meet TSS limitations. Boilers retiring by 2028 are
Industry groups and utilities argued, among other things,
be required only to meet TSS limitations.
that EPA withheld essential data, methodologies, and
analyses from the public record as confidential business
information. Other groups argued that EPA acted arbitrarily
Laura Gatz, Analyst in Environmental Policy
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Overview of the Steam Electric Pow er Generator Effluent Limitation Guidelines and Standards

IF10778


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