Updated November 27, 2019
Overview of the Steam Electric Power Generator Effluent
Limitation Guidelines and Standards
Overview
subcategory. In selecting BPT, EPA considers factors
The Clean Water Act (CWA) directs the Environmental
including the cost of applying the control technology in
Protection Agency (EPA) to regulate the discharge of
relation to the effluent reduction benefits, equipment
pollutants into waters of the United States. Such discharges
and facility age, and processes employed.
are prohibited without a permit. Thus, industrial dischargers
and others must obtain permits from states or EPA that set
 Best Available Technology Economically Achievable
limits on pollutants in their effluent. To guide the limits set
(BAT) generally represents the best existing
in permits for industrial dischargers, EPA issues Effluent
performance in the industrial category or subcategory.
Limitation Guidelines and standards (ELGs)—technology-
Factors considered include the cost of achieving effluent
based standards—for categories of industrial dischargers.
reductions and processes employed.
Since 1972, EPA has promulgated ELGs for 59 industrial
categories, including the steam electric power industry—
 New Source Performance Standards (NSPS) reflect the
which covers power plants that use nuclear or fossil fuels to
reductions achievable based on the best available
generate steam used to produce electricity.
demonstrated control technology. EPA is directed to
take into consideration the cost of achieving the effluent
In November 2015, EPA published revised ELGs (80
reduction and any non-water-quality environmental
Federal Register 67838) for the steam electric power
impacts and energy requirements.
industry to replace rules issued in 1982. EPA determined
that new ELGs were necessary to reflect changes in the
 Pretreatment Standards for Existing Sources (PSES) are
industry. For example, technology improvements since
designed to control the discharge of pollutants that pass
1982, particularly at coal-fired power plants, reduced
through, interfere with, or are otherwise incompatible
hazardous air emissions but increased discharges of other
with the operation of publicly owned treatment works.
pollutants, primarily heavy metals, to surface waters. EPA
PSES standards are analogous to BAT for direct
promulgated the 2015 rule to address those water quality
dischargers.
impacts by establishing new or additional requirements for
six wastestreams from steam electric power plants. In
 Pretreatment Standards for New Sources (PSNS) are
September 2017, EPA finalized a rule postponing
designed for the same purpose as PSES. EPA considers
compliance deadlines for two wastestreams to allow the
the same factors in promulgating PSNS as it does in
agency time to revise the limits set in the 2015 rule. In
promulgating NSPS.
November 2019, EPA proposed revisions to the 2015 final
rule for those two wastestreams (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 the
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
 Best Practicable Control Technology Currently
agency to commit to a schedule for issuing revised ELGs
Available (BPT) is based on the average of the best
for this industry. Pursuant to a consent decree, EPA
existing performance of plants within the industry or
promulgated a final rule in 2015. The 2015 rule includes
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link to page 2 Overview of the Steam Electric Power Generator Effluent Limitation Guidelines and Standards
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 reconsiders 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
pollutants
pollutants
change their associated compliance dates.


Dry handling control
Dry handling control
On November 4, 2019, EPA announced a proposed rule to
technology
technology
revise the ELGs applicable to FGD wastewater and BA
transport water. EPA proposes to change the technology
Bottom Ash (BA)
Zero discharge of
Zero discharge of
basis for treatment of the two wastestreams, noting that
Transport Water
pollutants
pollutants
since 2015, more affordable technologies capable of


removing similar pollutant amounts have become available.
Dry handling or closed
Dry handling or closed
EPA also proposes to establish new subcategories and
loop control
loop control
varying requirements for high flow facilities, low utilization
technology
technology
boilers, and boilers retiring by 2028.
Flue Gas Mercury
Zero discharge of
Zero discharge of
FGD wastewater: FGD wastewater dischargers that do not
Control
pollutants
pollutants
fall into any of the new subcategories would have numeric
Wastewater


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


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


selenium, and TDS and more stringent for mercury
Impoundment control
Chemical precipitation
compared to the 2015 rule. The proposed rule would add
technology
control technology
limitations for bromide and nitrate/nitrite. It would also
extend the timeline for the incentives program by five
Source: EPA, 80 Federal Register 67838-67903, November 3, 2015.
years.
Current Status
BA transport water: While the 2015 rule established a zero
Various stakeholders filed judicial petitions for review of
discharge standard for BA transport water, the proposed
the 2015 rule, which were consolidated in the U.S. Court of
rule would establish a not-to-exceed 10 percent volumetric
Appeals for the Fifth Circuit (Southwestern Elec. Power
purge limitation. For low utilization boilers, the proposed
Co. v. EPA, 5th Cir., 15-60821, filed November 20, 2015).
rule would require facilities to implement best management
Industry groups and utilities argued, among other things,
practice plans and meet TSS limitations. Boilers retiring by
that EPA withheld essential data, methodologies, and
2028 would be required only to meet TSS limitations.
analyses from the public record as confidential business
information. Other groups argued that EPA acted arbitrarily
by not requiring more stringent controls on discharges of
Laura Gatz, Analyst in Environmental Policy
bromide. In March and April 2017, EPA received petitions
IF10778
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Overview of the Steam Electric Power Generator Effluent Limitation Guidelines and Standards


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https://crsreports.congress.gov | IF10778 · VERSION 3 · UPDATED

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