[Federal Register Volume 84, Number 78 (Tuesday, April 23, 2019)]
[Proposed Rules]
[Pages 16810-16826]
[FR Doc No: 2019-08063]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 122

[EPA-HQ-OW-2019-0166; FRL-9991-72-OW]

Interpretive Statement on Application of the Clean Water Act
National Pollutant Discharge Elimination System Program to Releases of
Pollutants From a Point Source to Groundwater

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability of interpretive statement and request
for comment.

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SUMMARY: The Environmental Protection Agency (``EPA'') is issuing an
Interpretative Statement addressing whether the Clean Water Act (``the
CWA'' or ``the Act'') National Pollutant Discharge Elimination System
(``NPDES'') permit program applies to releases of a pollutant from a
point source to groundwater. This Interpretative Statement reflects the
EPA's consideration of the public comments received in response to its
February 20, 2018 Federal Register notice, as summarized immediately
below. Informed by those comments and based on a holistic analysis of
the statute, its text, structure, and legislative history, the Agency
concludes that the CWA is best read as excluding all releases of
pollutants from a point source to groundwater from NPDES program
coverage, regardless of a hydrologic connection between the groundwater
and jurisdictional surface water. The Interpretive Statement provides
the EPA's full analysis and rationale supporting its interpretation and
is available below and at https://www.epa.gov/npdes/releases-point-source-groundwater. Concurrently with issuing its interpretation of the
CWA, the Agency is soliciting additional public input regarding what
may be needed to provide further clarity and regulatory certainty on
this issue.

DATES: Comments must be received or postmarked on or before June 7,
2019.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OW-
2019-0166, at https://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. EPA may publish any comment
received to its public docket. Do not submit electronically any
information you consider to be Confidential Business Information (CBI)
or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit https://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Scott Wilson, Office of Wastewater
Management, Water Permits Division (MC4203M), Environmental Protection
Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460; telephone
number:<PHONE_NUMBER>; email address: [email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

    A. Does this action apply to me? Tribes, states, local governments,
the regulated community, and citizens interested in federal
jurisdiction over activities that may release pollutants to groundwater
may be impacted by this Interpretive Statement. Potentially affected
entities include:

------------------------------------------------------------------------
                                      Examples of potentially affected
             Category                             entities
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States, Tribes, and Territories...  State, Tribal, and Territorial water
                                     quality agencies and NPDES
                                     permitting authorities that may
                                     need to determine whether sources
                                     of pollutants should be addressed
                                     by standards or permitting actions.
Federal Agencies..................  Federal agencies with projects or
                                     other activities that may have
                                     releases that affect groundwater
                                     with connections to surface waters.
Industry..........................  Industries that may have releases
                                     that affect groundwater with
                                     connections to surface waters.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by EPA's
interpretation of the scope of the CWA NPDES program. Other types of
entities not listed in the table could also be affected. If you have
questions regarding the effect of this action on a particular entity,
please consult the person listed in the preceding FOR FURTHER
INFORMATION CONTACT section.
    B. How can I get copies of this document and other related
information? You may access this document electronically at https://www.epa.gov/npdes/releases-point-source-groundwater or at https://www.federalregister.gov. EPA has established an official public docket
for receiving comments under Docket ID No. EPA-HQ- OW-2019-0166 which
is accessible electronically at http://www.regulations.gov that will
also contain copies of this Federal Register notice and the
Interpretive Statement. The public docket does not include Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. The official public docket is the collection of
materials that is available for public viewing at the Water Docket in
the EPA Docket Center, (EPA/DC) EPA West, Room B102, 1301 Constitution
Ave. NW, Washington, DC. The EPA Docket Center Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the Water Docket is (202)
566-2426.

II. February 2018 Request for Public Comment

    On February 20, 2018, EPA requested public comment regarding
whether EPA should review and potentially revise or clarify its
previous statements concerning the applicability of the CWA NPDES
permit program to pollutant releases from point sources that reach
jurisdictional surface waters via groundwater that has a direct
hydrologic connection to a jurisdictional surface water (the ``direct
hydrologic connection theory''). 83 FR 7126, 7128 (Feb. 20, 2018). EPA
asked for specific comment on questions related to CWA authority, other
programs that address these releases, what issues needed further
clarification, and what format EPA should pursue if it chose to revise
or clarify its position. Id. EPA received over 50,000 comments in
response to its request. Comments addressed the

specific questions raised by EPA as well as other pertinent topics. EPA
received comments from a wide audience representing state governments,
local governments, tribes, industry, environmental organizations,
academia, and private citizens. See EPA Docket No. EPA-HQ-OW-2018-0063,
available at https://www.regulations.gov/docket?D=EPA-HQ-OW-2018-0063.
    Some commenters opposed the direct hydrologic connection theory on
programmatic and legal grounds. These comments raised concerns
regarding the activities that might be impacted if a NPDES permit is
required for a release to groundwater with a direct hydrologic
connection to jurisdictional surface water, including aquifer recharge,
leaks from sewage collection systems, septic system discharges,
treatment systems such as constructed wetlands, spills and accidental
releases, manure management and coal ash impoundment seepage. These
commenters also raised implementation concerns, including how a direct
hydrologic connection would be defined and where monitoring or the
point of compliance would be determined. Commenters opposed to the
direct hydrologic connection theory raised a range of legal arguments,
including that the theory was not grounded in the statutory text,
pointing in particular to the absence of the term ``groundwater'' from
sections authorizing the NPDES program and providing excerpts from the
Act's legislative history.
    Other commenters supported the direct hydrologic connection theory,
raising concerns based on the prior examples of environmental impacts
from releases to groundwater with a direct hydrologic connection to
jurisdictional surface water, and the importance of the authority to
regulate or prevent those releases pursuant to the CWA. These
commenters asserted that the CWA's goal of protecting surface waters
encompassed releases to groundwater that could reach jurisdictional
surface waters, and that groundwater itself does not need to be
jurisdictional under the CWA in order to regulate discharges that pass
through groundwater and ultimately may reach surface water.
    EPA has considered these comments, as well as the text, structure
and legislative history of the CWA, and concludes that the
interpretation expounded in the Interpretative Statement below is the
best, if not the only, reading of the CWA, is more consistent with
Congress's intent than other interpretations of the Act, and best
addresses the question of NPDES permit program applicability for
pollutant releases to groundwater within the authority of the CWA.

III. Interpretive Statement

Interpretive Statement

    Subject: Application of the Clean Water Act National Pollutant
Discharge Elimination System Program to Releases of Pollutants From a
Point Source to Groundwater.
    From: Matthew Z. Leopold (signed and dated April 12, 2019), General
Counsel.
    David P. Ross (signed and dated April 12, 2019), Assistant
Administrator for Water.
    To: Regional Administrators, Regions I-X.
    This Interpretive Statement sets forth the Environmental Protection
Agency's (``EPA'' or ``the Agency'') interpretation of the Clean Water
Act (``the CWA'' or ``the Act'') National Pollutant Discharge
Elimination System (``NPDES'') permit program's applicability to
releases of pollutants from a point source to groundwater that
subsequently migrate or are conveyed by groundwater to jurisdictional
surface waters. For the reasons explained below, EPA concludes that the
Act is best read as excluding all releases of pollutants from a point
source to groundwater from NPDES program coverage and liability under
Section 301 of the CWA, regardless of a hydrologic connection between
the groundwater and a jurisdictional surface water. See 33 U.S.C.
1311(a), 1342.
    This Interpretive Statement is the first instance in which the
Agency has issued guidance focused exclusively on whether NPDES permits
are required for releases of pollutants to groundwater that reach
surface water. As described further below, there is a mixed record of
prior Agency statements addressing this issue and a split in the
federal circuit courts regarding the application of the NPDES permit
program to releases of pollutants to groundwater that reach
jurisdictional surface waters. Recent judicial decisions addressing
this issue contribute to an evolving and increasingly confusing legal
landscape in which permitting and enforcing agencies, potentially
regulated parties, and the public lack clarity on when the NPDES
permitting requirement set forth in sections 301 and 402 of the CWA may
be triggered by releases of pollutants to groundwater. The absence of a
dedicated EPA statement on the best reading of the CWA has generated
confusion in the courts and uncertainty for EPA regional offices and
states implementing the NPDES program, regulated entities, and the
public. This Interpretive Statement is intended to advise the public on
how EPA interprets the relevant provisions of the CWA.
    This Interpretive Statement conveys to EPA's regional offices,
states, and the public the Agency's reading of the applicability of
sections 301 and 402 of the CWA to releases of pollutants to
groundwater. It contains the Agency's most comprehensive analysis of
the CWA's text, structure, legislative history, and judicial decisions
that has been lacking in prior Agency statements on this issue. EPA
thus herein provides clear guidance that balances the statute, case
law, and the need for clarity on the scope of the CWA NPDES coverage,
which has been recently expanded by judicial decision to potentially
reach a new set of releases to groundwater that EPA has not
historically regulated in the NPDES program. This Interpretive
Statement provides important clarity to inform future permitting
decisions and other actions; it neither alters legal rights or
obligations nor changes or creates law.
    In February 2018, the Agency sought public comment on whether the
NPDES permit program applies to releases of pollutants to groundwater
and whether the Agency should revise or clarify its position on this
issue. See 83 FR 7126, 7128 (Feb. 20, 2018). Informed by those comments
and based on a holistic analysis of the statute, its text, structure,
and legislative history, the Agency concludes that the best, if not the
only, reading of the CWA is that Congress intentionally chose to
exclude all releases of pollutants to groundwater from the NPDES
program, even where pollutants are conveyed to jurisdictional surface
waters via groundwater. Congress purposely structured the CWA to give
states the responsibility to regulate such releases under state
authorities. And, as discussed further below, other federal statutes
contain explicit provisions that regulate the release of pollutants
into groundwater to provide significant federal authority to address
groundwater pollution not provided by the NPDES permitting program. In
accordance with Congress's intent, state and federal authorities are
collectively available to provide protection for ground and surface
water quality in those instances where direct CWA permitting authority
is not applicable.
    During the pendency of EPA's review of the public comments
received, two petitions for certiorari were filed with the Supreme
Court which posed the question of whether the CWA applies to releases
of pollutants from a point source to groundwater that migrates to
surface water. See Petition for Writ of

Certiorari, Cty. of Maui v. Hawai'i Wildlife Fund, et al. (``County of
Maui''), No. 18-260 (Aug. 27, 2018); Petition for Writ of Certiorari,
Kinder Morgan Energy Partners, L.P. v. Upstate Forever (``Kinder
Morgan''), No. 18-268 (Aug. 28, 2018). Consistent with the United
States' recommendation set forth in an amicus brief filed at the
Court's request, the Supreme Court recently granted the petition for
writ certiorari in County of Maui, an appeal of the Ninth Circuit's
broad reading of the CWA. Cty. of Maui, No. 18-260 (S. Ct. cert granted
on Feb. 19, 2019). Issuing this statement provides necessary clarity on
the Agency's interpretation of the statute given the mixed record of
prior Agency statements and a split in the federal circuit courts
regarding this issue.
    The interpretation contained herein differs from the direct
hydrological connection theory, expressed in the United States amicus
brief filed in the Ninth Circuit County of Maui proceeding, and the
theories advanced by the parties in that case. The Agency does not
agree with the respondents' and Ninth Circuit's view that the CWA's
NPDES requirements can apply when a pollutant released from a point
source migrates to navigable waters through groundwater. The
differences between the direct hydrological connection theory and
today's interpretation, and EPA's explanation for why the Agency is
modifying and clarifying its interpretation, are detailed below. While
the Agency disagrees with the reasoning of the Ninth Circuit's decision
in County of Maui, as well as the reasoning of the Fourth Circuit in
its Kinder Morgan decision, for reasons discussed further below, it
will nonetheless apply the decisions of those courts in their
respective circuits until further clarification from the Supreme Court.
See Hawai'i Wildlife Fund v. Cty. of Maui, 886 F.3d. 737 (9th Cir.
2018); Upstate Forever v. Kinder Morgan Energy Partners, L.P., 887 F.3d
637, 652 (4th Cir. 2018). Thus, the Agency's interpretation set forth
herein applies at this time only outside of the Fourth and Ninth
Circuits.\1\
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    \1\ Neither the Ninth Circuit decision nor Fourth Circuit
decision prohibits application of the Agency's interpretation
expressed in this action in those circuits. See National Cable
Telecomms Ass'n v. Brand X internet Servs., 545 U.S. 967, 982 (2005)
(``A court's prior judicial construction of a statute trumps an
agency construction otherwise entitled to Chevron deference only if
the prior court decision holds that its construction follows from
the unambiguous terms of the statute and thus leaves no room for
agency discretion.''). As explained herein, by not applying this
interpretation in the Ninth and Fourth Circuits, the Agency is
simply choosing to maintain the status quo pending further
clarification by the Supreme Court, after which time the Agency
intends to follow with notice and comment rulemaking.
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I. Factual Background

    It is a fundamental principle of hydrology that many groundwaters
and surface waters are linked through the hydrologic cycle. As the
Agency has previously explained, the ``hydrologic cycle involves the
continual movement of water between the earth and the atmosphere
through evaporation and precipitation.'' EPA 440/6-90-004, Citizen's
Guide to Ground-Water Protection (1990). Rain and snow fall to the
earth, and the resulting water runs into surface waters, evaporates, is
absorbed by plant roots, or infiltrates the ground's surface and moves
downward to the saturated zone, ``the area in which all interconnected
spaces in rocks and soil are filled with water,'' also known as
groundwater. Id. at 1. In areas where the saturated zone occurs at the
ground's surface, groundwater discharges into surface waters,
eventually evaporating into the atmosphere to form precipitation and
begin the hydrologic cycle again. Id.
    The nature of the connection between groundwater and surface water
is highly dependent on local climate, topography, geology and the type
of groundwater formation at issue. Because of the often-slow movement
of groundwater, pollutants tend to remain concentrated in the form of a
plume. The speed and concentration at which pollutants move through
groundwater depend on the amount and type of pollutant, its solubility
and density, and the speed of the surrounding groundwater. The amount
of a pollutant that is released into groundwater that will eventually
reach surface water also varies and is dependent on both the
characteristics of the pollutant itself as well as site-specific
factors. In addition, the travel time and distance between polluted
groundwater and surface water can allow for the reduction of the
impacts of contamination on the surface water due to natural processes.
These processes include, for example, dilution, oxidation, biological
degradation (which can render pollutants less toxic), and the binding
of materials to soil particles such that pollutants are adsorbed by
surrounding soil before reaching surface water.
    Many commenters responding to EPA's February 2018 Federal Register
notice identified activities that have not generally been required to
obtain an NPDES permit and might be impacted if a permit were required
for a release to groundwater with a hydrologic connection to
jurisdictional surface waters. Activities listed by commenters included
aquifer recharge, leaks from sewage collection systems, septic system
discharges, treatment systems such as constructed wetlands, spills and
accidental releases, manure management, and coal ash impoundment
seepage.
    Septic systems, for example, generally operate by discharging
liquid effluent into perforated pipes buried in a leach field,
chambers, or other special units designed to slowly release the
effluent into soil. The soil accepts, treats, and disperses wastewater
as it percolates through the soil, but can in certain circumstances
ultimately enter groundwater. Over 26 million homes in the United
States employ septic systems to treat and dispose of household waste.
As the Agency has explained, ``[r]ecycled water from a septic system
can help replenish groundwater supplies; however, if the system is not
working properly, it can contaminate nearby waterbodies.'' See EPA,
Septic Systems and Surface Water, https://www.epa.gov/septic/septic-systems-and-surface-water. But even well-functioning septic systems can
contribute pollutants such as nutrients to groundwater. In addition to
household waste disposal, releases to groundwater are also employed as
part of green infrastructure projects, including the management of
stormwater. These projects release stormwater and recycled wastewater
to the ground to recharge depleted aquifers and prevent or reduce
runoff to surface waters. In arid western states experiencing low
rainfall, states and municipalities use such surface infiltration of
recycled wastewaters not only to replenish groundwater supplies, but
also to mitigate salt water intrusion or abate land subsidence that can
occur where groundwater is overly depleted.
    To date, neither EPA nor states have generally required NPDES
permits for these types of activities, and in the select instances
where NPDES permits have been required for discharges from a point
source that reach jurisdictional surface waters via groundwater, they
have been based on site-specific factors.

II. The Clean Water Act

    The objective of the CWA is ``to restore and maintain the chemical,
physical, and biological integrity of the Nation's waters.'' 33 U.S.C.
1251(a). In order to meet that objective, Congress declared two
national goals: (1) ``that the discharge of pollutants into the
navigable waters be eliminated by 1985;'' and (2) ``that wherever
attainable, an interim goal of water quality which provides for the
protection and propagation of fish,

shellfish, and wildlife and provides for recreation in and on the water
be achieved by July 1, 1983. . . .'' Id. Sec.  1251(a)(1)-(2). The CWA
approaches restoration and protection of the Nation's waters as a
partnership between states and the federal government, assigning
certain functions to each in striking the balance of the statute's
overall regulatory scheme. Congress expressly recognized the role that
states would continue to exercise in preventing, reducing, and
eliminating pollution: ``It is the policy of Congress to recognize,
preserve, and protect the primary responsibilities and rights of States
to prevent, reduce, and eliminate pollution, to plan the development
and use (including restoration, reservation, and enhancement) of land
and water resources[.]'' Id. Sec.  1251(b). As the Supreme Court has
explained, the statute ``anticipates a partnership between the States
and the Federal Government,'' toward a shared objective of restoring
and maintaining the integrity of the Nation's waters. Arkansas v.
Oklahoma, 503 U.S. 91, 101 (1992).
    To accomplish the Act's broad national objective, Congress
established respective roles for the federal government and for states.
As one means of accomplishing the Act's objective, Congress prohibited
any ``discharge of any pollutant'' to ``navigable waters'' or to the
``contiguous zone or the ocean'' unless it is authorized by the
statute, generally by a NPDES permit. 33 U.S.C. 1311(a) (``Except as in
compliance with this section and sections 1312, 1316, 1317, 1328, 1342,
and 1344 of this title, the discharge of any pollutant by any person
shall be unlawful.''). The Act defines navigable waters as ``the waters
of the United States, including the territorial seas.'' Id. Sec.
1362(7). EPA's regulations have never defined ``waters of the United
States'' to include groundwater.
    The statute defines ``discharge of a pollutant'' as ``any addition
of any pollutant to navigable waters from any point source'' or ``any
addition of any pollutant to the waters of the contiguous zone or the
ocean from any point source other than a vessel or other floating
craft.'' 33 U.S.C. 1362(12). A point source is defined as ``any
discernible, confined, and discrete conveyance, including but not
limited to any pipe, ditch, channel, tunnel, conduit, well, discrete
fissure, container, rolling stock, concentrated animal feeding
operation, or vessel or other floating craft, from which pollutants are
or may be discharged.'' Id. Sec.  1362(14).
    Where there is a discharge of a pollutant from a point source to a
water of the United States, termed herein a jurisdictional surface
water, NPDES permits generally require permittees to meet numeric or
narrative effluent limitations. Id. Sec. Sec.  1311(a), 1342(a).
Effluent limitations are defined as ``any restriction established by a
State or the Administrator on quantities, rates, and concentrations of
chemical, physical, biological, and other constituents which are
discharged from point sources into navigable waters, the waters of the
contiguous zone, or the ocean, including schedules of compliance.'' Id.
Sec.  1362(11).
    Courts have observed that nonpoint source pollution--the broad
category of other forms of water pollution that do not fall within the
point source definition and not defined under the Act--can be
understood as ``all water quality problems not subject to Section
402,'' the portion of the statute requiring NPDES permits. Nat'l
Wildlife Fed'n v. Gorsuch, 693 F.2d 156, 166 (D.C. Cir. 1982). In
addition to the NPDES permitting program, as another means of
accomplishing the Act's objective, Congress reserved to states their
exclusive role in regulating nonpoint source pollution. Am. Farm Bureau
Fed'n v. EPA, 792 F.3d 281, 289 (3rd Cir. 2015) (``States in turn
regulate nonpoint sources. There is significant input and oversight
from the EPA, but it does not regulate nonpoint sources directly.'');
see also Or. Natural Desert Ass'n v. U.S. Forest Serv., 550 F.3d 778,
780 (9th Cir. 2008) (``The CWA's disparate treatment of discharges from
point sources and nonpoint sources is an organizational paradigm of the
Act.'').
    While the point and nonpoint source distinction is the
quintessential inquiry related to the discharge of pollutants to
surface waters, as explained further below, this inquiry is not
relevant as applied to groundwater. Rather, the text, structure, and
legislative history of the CWA demonstrate Congress's intent to leave
the regulation of groundwater wholly to the states under the Act. See,
e.g., Village of Oconomowoc Lake v. Dayton Hudson Corporation, 24 F.3d
962, 965 (7th Cir. 1994) (``[T]he Clean Water Act does not attempt to
assert national power to the fullest . . . . Congress elected to leave
[regulation of groundwaters] to state law[.]''); Tenn. Clean Water
Network v. TVA, 905 F.3d 436, 439 (6th Cir. 2018) (``[T]he CWA is
restricted to regulation of pollutants discharged into navigable waters
. . . leaving the states to regulate pollution of non-navigable
waters'' such as groundwater.).

III. EPA's Interpretation of the Clean Water Act National Pollutant
Discharge Elimination System Program's Applicability to Releases of
Pollutants to Groundwater That May Reach Jurisdictional Surface Waters

    The CWA's definition of the ``discharge of [a] pollutant,'' 33
U.S.C. 1311(a), includes ``any addition of any pollutant to navigable
waters from any point source,'' 33 U.S.C. 1362(12)(A). Because
groundwater is not a ``navigable water[[hairsp]],'' see 33 U.S.C.
1362(7), the CWA does not regulate discharges to groundwater as such.
But the question of whether a ``discharge'' within the statute's
meaning has occurred when a pollutant is released from a point source,
travels through groundwater, and ultimately migrates to navigable
waters has generated confusion and uncertainty.\2\
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    \2\ This Interpretative Statement addresses the applicability of
the CWA NPDES permitting requirements to the release of pollutants
from a point source to groundwater that reach jurisdictional surface
waters through hydrologically connected groundwater. It describes
the movement of pollutants to and through groundwater as having been
released from a point source. When the term ``discharge'' is used
herein to reference pollutants being added to a surface water by or
through groundwater, this does not connote or imply that a
``discharge of a pollutant'' or ``discharge'' has occurred under the
CWA. See 33 U.S.C. 1362(12) (``discharge of a pollutant''), 1362(16)
(``discharge'').
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    Commenters to EPA's February 2018 Federal Register notice rely
primarily on one of two interpretive possibilities for addressing this
question. One approach is reflected in the court of appeals' decisions
in County of Maui and Kinder Morgan. In those cases, the courts
interpreted Section 1362(12)(A) as applying to discharges from a point
source to navigable waters where the pollutant has travelled to the
navigable water over or through another medium. On this view, to
qualify as a discharge ``to navigable waters,'' a discharge via
groundwater must, in the Ninth Circuit, be ``fairly traceable'' back to
the point source and more than de minimis, Cty. of Maui, 886 F.3d at
746 n.2, and in the Fourth Circuit, ``must be sufficiently connected to
navigable waters,'' Kinder Morgan, 887 F.3d at 651. Those courts and
commentators who have endorsed these variations on a similar approach
have differed in describing the type of connection that qualifies under
the CWA, but they generally agree that a ``discharge of a pollutant''
may occur when a pollutant has been added to a navigable water via
groundwater with some connection to the navigable water.
    A second interpretive approach is reflected in the Sixth Circuit's
decision in Kentucky Waterways Alliance v. Kentucky Utilities Co., 905
F.3d 925 (6th

Cir. 2018). In that case, the court read the relevant statutory
language as applying only where pollution has been added directly to
navigable waters ``by virtue of a point-source conveyance,'' rather
than through some other mechanism (such as groundwater). Id. at 934.
Under this interpretation, sometimes described as the ``terminal point
source'' theory, any intermediary between the point source and the
navigable water means that a pollutant has not been discharged ``to
[the] navigable water[[hairsp]] from [the] point source.''
    EPA's interpretation differs from these two theories. The Agency's
view is that the best, if not the only, reading of the statute is that
all releases to groundwater are excluded from the scope of the NPDES
program, even where pollutants are conveyed to jurisdictional surface
waters via groundwater. This interpretation is appropriately tailored
to releases to groundwater. On this view, because the CWA clearly
evinces a purpose not to regulate groundwater, and because groundwater
is extensively regulated under other statutory regimes, discussed
further below in section VI.B, any circumstance in which a pollutant is
released from a point source to groundwater is categorically excluded
from the CWA's coverage. The interposition of groundwater between a
point source and the navigable water thus may be said to break the
causal chain between the two, or alternatively may be described as an
intervening cause. Today's interpretation pertains to releases to
groundwater and thus leaves in place the Agency's case-by-case approach
to determining whether pollutant releases to jurisdictional surface
waters that do not travel through groundwater require an NPDES permit.
Whether a permit is required for such a release is necessarily a fact-
specific inquiry, informed by the point source definition and an
analysis of intervening factors.
    In the Agency's view, the text, structure, and legislative history
of the CWA, as well as the better-reasoned judicial decisions, support
the legal conclusion that Congress intended to exclude all releases of
pollutants to groundwater from NPDES program coverage, regardless of a
hydrologic connection or conveyance to jurisdictional surface water.
When attempting to interpret a statute, a court or agency cannot look
to one single word or phrase, but instead must look to the text as a
whole. See Star Athletica, LLC v. Varsity Brands, Inc., 137 S. Ct.
1002, 1010 (2017); Dole v. United Steelworkers of Am., 494 U.S. 26, 35
(1990) (``[W]e are not guided by a single sentence or member of a
sentence, but look to the provisions of the whole law, and to its
object and policy.''). While no single provision of the CWA expressly
addresses whether pollutants discharged from a point source that reach
jurisdictional surface waters through groundwater are subject to NPDES
permitting requirements, when analyzing the statute in a holistic
fashion, Congress's intent becomes evident: Congress did not intend for
the NPDES program to address any pollutant discharges to groundwater,
even where groundwater may be hydrologically connected to surface
waters. Relevant legislative debate confirms that Congress fully
understood the hydrologic connections that exist between groundwater
and surface water, yet chose this jurisdictional line to strike the
balance between state and federal responsibility for protection of the
Nation's waters.
    Congress was explicit where it intended the Act to apply to
groundwater. It included references to groundwater in provisions aimed
at providing information, guidance, and funding to states, to enable
them to regulate pollutant discharges to groundwater. Explicit
reference to groundwater, by contrast, is absent in the operative
regulatory sections of the Act. Further, Congress refers to
groundwaters exclusively as one unified category of waters; the Act is
devoid of any indication that Congress viewed releases of pollutants to
groundwater as susceptible to different treatment under the Act based
on the presence or absence of a connection to surface water. The
legislative history is unambiguous that Congress was aware of the
potential for releases to groundwater to reach surface water, and
nonetheless rejected proposed amendments seeking to require NPDES
permits for discharges to groundwater. As with nonpoint source
pollution, the statute's structure and references to groundwater
therein are reflective of Congress's intent to leave regulation of
releases of pollutants to groundwater with the states.
    A. The operative, enforceable provisions of the Clean Water Act
that make up the NPDES permitting program neither reference nor
contemplate releases to groundwater.
    The foundational definitional terms and provisions that establish
the NPDES program extend only to discharges of pollutants to navigable
waters, waters of the contiguous zone, and the ocean, i.e., discharges
to jurisdictional surface waters. The Act provides that a NPDES permit
may be issued ``for the discharge of any pollutant.'' 33 U.S.C.
1342(a). The definition of discharge of a pollutant refers to ``any
addition of any pollutant to navigable waters from any point source,''
or ``any addition of any pollutant to the waters of the contiguous zone
or the ocean from any point source.'' Id. Sec.  1362(12) (emphasis
added). The Act thus explicitly refers to the addition of any pollutant
to three of the four categories of waters referred to throughout the
statute; the addition of any pollutant to groundwater--the fourth
category--is notably absent. Congress specified which sections of the
Act applied to which categories of waters: groundwater, navigable
waters, contiguous zone waters, and the ocean. See, e.g., id. Sec.
1254(a)(5) (setting forth provisions aimed at monitoring the quality of
``the navigable waters and ground waters and the contiguous zone and
the oceans''); Sec.  1314(a)(2) (requiring that the Administrator shall
publish information on the ``factors necessary to restore and maintain
the chemical, physical, and biological integrity of all navigable
waters, ground waters, waters of the contiguous zone, and the
oceans''). In other words, ``when Congress wanted certain provisions of
the CWA to apply to groundwater, it stated so explicitly.'' Umatilla
Waterquality Protective Ass'n. v. Smith Frozen Foods, 962 F. Supp.
1312, 1318 (D. Or. 1997).
    Congress also elected to leave groundwater out of the definition of
``effluent limitations'' and related provisions. Effluent limitations
are defined as ``any restriction established by a State or the
Administrator on quantities, rates, and concentrations of chemical,
physical, biological, and other constituents which are discharged from
point sources into navigable waters, the waters of the contiguous zone,
or the ocean, including schedules of compliance.'' 33 U.S.C. 1362(11)
(emphasis added). Similarly, section 304(g), establishing the
requirement that EPA publish certain guidelines to assist states in
implementing their NPDES program, provides that these guidelines will
apply to control discharges to every form of water except groundwater.
See id. Sec.  1314(g) (providing that, for the purposes of assisting
states in carrying out NPDES programs, EPA shall publish guidelines
``to control and prevent the discharge into the navigable waters, the
contiguous zone, or the ocean'').
    The absence of groundwater in the sections of the statute
foundational to the NPDES permitting program is meaningful: ``[a]
familiar principle of statutory construction . . . is that a negative
inference may be drawn from the exclusion of language from one

statutory provision that is included in other provisions of the same
statute.'' Hamdan v. Rumsfeld, 548 U.S. 557, 578 (2006). Here, Congress
elected not to include groundwater in the definition of ``discharge of
a pollutant''--the critical definition in determining whether a NPDES
permit is required--nor did Congress include groundwater in the
definition of ``effluent limitations,'' a primary vehicle in
implementing the NPDES permitting requirement. See Umatilla, 962 F.
Supp. at 1318 (``[T]hroughout the CWA, Congress appeared to have four
categories of waters in mind--`navigable waters,' the contiguous zone,
the ocean, and `ground waters.' Only the first three of these . . . are
included within the definition of `discharge of a pollutant,'
indicating that Congress did not consider discharges to groundwater to
be discharges that would trigger the NPDES requirement.'').
    Congress's intent to deliberately leave groundwater out of the
definition of ``discharge of a pollutant'' is confirmed by the
legislative history of the Act. In a hearing before the House Public
Works Committee, Representative Leslie Aspin recommended that the term
``ground water'' be added to the operative NPDES provisions so that
discharges to groundwater also would be covered by the statute,
explaining that ``[s]ometimes a navigable water and ground-water source
run into each other, or come close to each other, so that seepage from
polluted ground-water source could pollute the navigable water[;] . . .
[t]o say that the Federal Government can regulate the ecology of one,
but not the other, is silly and counterproductive.'' Water Pollution
Control Legislation-1971 (Proposed Amendments to Existing Legislation):
Hearings before the H. Comm. on Pub. Works, 92nd Cong. 793 (1971)
(remarks of Rep. Aspin) (emphasis added).
    Representative Aspin went on to propose an amendment to regulate
groundwater under the NPDES program by amending Title IV of the statute
to include explicit references to groundwater and adding the term
``ground waters'' to the definition of ``discharge of pollutant'' found
in Section 502(12). He explained that these amendments were necessary
given the likelihood that polluted groundwater would contaminate
jurisdictional surface waters:

    The amendment brings ground water into the subject of the bill,
into the enforcement of the bill. Ground water appears in this bill
in every section, in every title except title IV. It is under the
title which provides EPA can study ground water. It is under the
title dealing with definitions. But when it comes to enforcement,
title IV, the section on permits and licenses, then ground water is
suddenly missing. That is a glaring inconsistency which has no
point. If we do not stop pollution of ground waters through seepage
and other means, ground water gets into navigable waters, and to
control only the navigable water and not the ground water makes no
sense at all.

    118 Cong. Rec. 10,666 (1972), 1 Leg. Hist. 589 (remarks of Rep.
Aspin) (emphasis added). The amendments were rejected by a vote of 86
to 34. Id. at 597. The failure of a proposed amendment ``strongly
militates against a judgment that Congress intended a result that it
expressly declined to enact.'' Gulf Oil Corp. v. Copp Paying Co., 419
U.S. 186, 200 (1974).
    The only section in the extensive NPDES permitting provisions where
discharges to groundwater are contemplated is section 402(b)(1)(D),
which sets forth the requirements for EPA approval of state programs to
assume NPDES authority. This section requires that to approve a state-
submitted NPDES program, the Administrator must determine that adequate
authority exists within the state to ``control the disposal of
pollutants into wells.'' 33 U.S.C. 1342(b)(1)(D). The Fifth Circuit
found this provision significant in rejecting EPA's prior view that it
had authority to regulate groundwater pollution resulting from deep-
well disposal, observing that ``[t]he simple requirement of Sec.
402(b)(1)(D) that state permit programs have adequate authority to
issue permits which control the disposal of pollutants into wells,
which is not fleshed out elsewhere in the Act or mirrored in any of the
sections setting forth the Administrator's powers, is entirely
consistent'' with Congress's intention to ``stop short of establishing
federal controls over groundwater pollution.'' Exxon Corp. v. Train,
554 F.2d 1310, 1324 (5th Cir. 1977).
    The legislative history of 402(b)(1)(D) illuminates Congress's
intent in the CWA to require states, but not the federal government, to
regulate deep well disposal, which is consistent with its intent to
leave regulation of all pollutant discharges to groundwater to states.
The Senate Committee on Public Works report explains that, like the
House, the Senate Committee rejected amendments to impose federal
regulation over groundwater but included the provision in section
402(b)(1)(D) requiring states to maintain programs to regulate deep
well disposal to encourage states to carry out such regulation.
Specifically, the report explained that:

    Several bills pending before the Committee provided authority to
establish Federally approved standards for groundwaters which
permeate rock, soil, and other subsurface formations. Because the
jurisdiction regarding groundwaters is so complex and varied from
State to State, the Committee did not adopt this recommendation.
    The Committee recognizes the essential link between ground and
surface waters and the artificial nature of any distinction. Thus
the Committee bill requires in section 402 that each State include
in its program for approval under section 402 affirmative controls
over the injection or placement in wells of any pollutants that may
affect ground water. This is designed to protect ground waters and
eliminate the use of deep well disposal as an uncontrolled
alternative to toxic and pollution control.
    The importance of groundwater in the hydrological cycle cannot
be underestimated. Although only about 21.5 percent of our domestic,
industrial[,] [and] agricultural supply comes directly from wells,
it must be remembered that rivers, streams and lakes themselves are
largely supplied with water from the ground--not surface runoff.

    S. Rep. No. 414, 92d Cong., 1st. Sess. at 73 (1971), 2 Legislative
History of the Water Pollution Control Act Amendments of 1972, at 1491
(emphasis added); see also 118 Cong. Rec. 10667 (1972), 1 Leg. Hist.
591 (remarks of Rep. Clausen) (opposing amendment to require NPDES
permits for discharges to groundwater and stating that the House
committee had ``recognized the need for control of disposal of
pollutants into wells in order to protect our ground waters. Therefore,
in section 402(b)(1)(D) we provided that the Administrator shall
approve a State program unless he determines that authority does not
exist to control the disposal of pollutants into wells.'').
    The legislative history makes evident that Congress declined to
extend coverage of the NPDES program to discharges to groundwater and
did so with the understanding that releases of pollutants to
groundwater often reached jurisdictional surface water and could affect
its quality. For example, at a 1971 hearing before the Senate Public
Works Committee, then EPA Administrator William Ruckelshaus requested
that EPA be granted authority to regulate groundwater quality,
explaining the basis for that request as follows:

    The only reason for the request for Federal authority over
ground waters was to assure that we have control over the water
table in such a way as to insure that our authority over interstate
and navigable streams cannot be circumvented, so we can obtain water
quality by maintaining a control over all the sources of pollution,
be they discharged directly into any stream or through the ground
water table.

    Water Pollution Control Legislation-1971 (Proposed Amendments to

Existing Legislation): Hearings before the H. Comm. on Pub. Works, 92nd
Cong. 230 (1971) (statement of Hon. William Ruckelshaus, Administrator,
EPA) (emphasis added). This statement, before the same Senate Committee
that rejected amendments to extend the scope of the NPDES program at
the time of the passage of the Act, supports the conclusion that
Congress was aware that contaminated groundwater could reach
jurisdictional surface waters and nonetheless chose to leave releases
to groundwater to state regulation in the CWA paradigm. As the Fifth
Circuit observed in analyzing this legislative history, throughout the
ensuing debate ``there is not the slightest hint that any Member
thought the bill would grant the Administrator any power to regulate
deep-well disposal or any other form of groundwater pollution. Instead,
all the evidence points to precisely the opposite understanding.''
Exxon, 554 F.2d at 1329; see also Kelley on behalf of Michigan v.
United States, 618 F. Supp. 1103, 1107 (W.D. Mich. 1985) (acknowledging
the ``unmistakably clear legislative history . . . demonstrat[ing] that
Congress did not intend the Clean Water Act to extend federal
regulatory and enforcement authority over groundwater contamination'').
    B. Explicit references to groundwater are found in sections of the
Act that serve to provide information, guidance, assistance, or funding
to states in regulating groundwater, and in sections of the Act
addressing state programs to control nonpoint source pollution.
    The Act's provisions explicitly addressing groundwater can be
placed into two groups. Analysis of these two groups of statutory
references reinforces Congress's intent to leave regulation of
groundwater--no matter how hydrologically connected to surface water--
to the states. First, the Act contains forward-looking sections aimed
at gathering information that could inform subsequent legislation and
current state efforts to regulate discharges to groundwater. Indeed,
``a clear pattern of congressional intent with respect to groundwaters
emerges upon close examination of those sections of the Act that deal
with the subject. That pattern is one of information gathering and
encouragement of state efforts to control groundwater pollution--but
not of direct federal control over groundwater pollution.'' See Exxon,
554 F.2d at 1322. Second, the Act contains sections addressing state
programs to manage nonpoint source pollution, evidencing Congress's
intent to retain states' lead role with respect to both nonpoint source
and groundwater pollution. The provisions described below are
reflective of Congress's intent that states retain responsibility for
addressing groundwater pollution, and that the federal government's
role would be to provide resources, both in the form of information,
funding or other support, for states to take on this issue. These
resources and incentives for state programs, like the NPDES program,
are an important component of the CWA, but one in which states retain
regulatory decision-making and authority and elect to what extent they
chose to utilize federal support.
    Groundwater is first mentioned in the statute in Title I, setting
forth ``Research and Related Programs.'' This Title contains several
provisions directing EPA to address groundwater pollution through
information gathering and coordination with states, as opposed to
through binding regulatory requirements found elsewhere in the Act.
See, e.g., 33 U.S.C. 1252, 1254. During the debate on the amendment to
regulate discharges to groundwater through the NPDES program,
Representative Donald H. Clausen, a member of the House Committee on
Public Works and sponsor of the House bill, noted in explaining his
opposition to the amendment that ``it was determined by the committee
that there was not sufficient information on ground waters to justify
the types of controls that are required for navigable waters.'' 118
Cong. Rec. 10667 (1972), 1 Leg. Hist. 591 (remarks of Rep. Clausen). He
explained that the Committee recognized the need for additional
information and research ``both in determining the effect of
underground disposal of pollutants and the migration of such
pollutions.'' Id. Thus, the Committee drafted ``broad research'' powers
for EPA under Title I of the statute, and, based on that research, in
the future, ``Congress might have a basis for determining the need and
appropriately extending the controls of H.R. 11896 as they apply to
navigable waters to ground waters if needed.'' Id.
    Congress also included non-regulatory provisions focused on the
protection of groundwater in Title II of the Act, in which Congress
authorized EPA to make grants to states for the construction of
publicly owned treatment works (POTWs). Of relevance here, Congress
included a provision in section 202 authorizing increased funding for
construction of POTWs if states provide a certificate indicating that
the quantity of available groundwater will be ``insufficient,
inadequate, or unsuitable for public use, including the ecological
preservation and recreational use of surface water bodies,'' unless
effluents from POTWs, after adequate treatment, are returned to the
groundwater. 33 U.S.C. 1282(b)(2). This is an example of ``Congress
employ[ing] the power of the federal purse to encourage protection by
the states of underground waters.'' Exxon, 554 F.2d at 1323. Notably,
this provision also links the quantity of available groundwater to
``ecological preservation and recreational use of surface water
bodies,'' 33 U.S.C. 1282(b)(2), indicating Congress's decision to
explicitly acknowledge and account for the connection between
groundwater and jurisdictional surface waters when it chose to do so.
    Title III of the CWA, ``Standards and Enforcement,'' also contains
several provisions related to groundwater, each of which set forth non-
regulatory information gathering requirements and provisions for
guidance or funding to states. Section 304(a)(1) of the statute
requires that the Administrator develop and publish water quality
criteria, on, in pertinent part, the kind and extent of identifiable
effects on health and welfare ``which may be expected from the presence
of pollutants in any body of water, including ground water.'' 33 U.S.C.
1314(a)(1). Section 304(a)(2) requires that the Administrator develop
and publish information on the factors necessary to restore and
maintain the chemical, physical, and biological integrity of all
navigable waters and ground waters. Id. Sec.  1314(a)(2). Neither
Section 304(a)(1) nor section 304(a)(2), however, create compliance
obligations for individual dischargers. E. I. Du Pont de Nemours & Co.
v. Train, 430 U.S. 112, 119 n.6 (1977) (``There is no provision for
compliance with Sec.  304, the guideline section.''). Rather, EPA's
role in executing Section 1314(a) is to provide guidance to states.
City of Albuquerque v. Browner, 865 F. Supp. 733, 738 (D.N.M. 1993)
(``Section 304(a) of the Act requires EPA to develop criteria for water
quality that reflect the latest scientific knowledge, and to provide
those criteria to the States as guidance.''). As the Fifth Circuit
observed, ``the absence of other provisions in the Act . . . for
transforming this information into enforceable limitations, strongly
suggests that Congress meant to stop short of establishing federal
controls over groundwater pollution, at least for the time being.''
Exxon, 554 F.2d at 1325.
    These provisions providing for support to states to regulate
groundwater arise in the context of general informational support to
states (sections 102, 104, and 304) and funding tied to protection of
groundwater related to discharges from a specific type of

facility (section 202). 33 U.S.C. 1252, 1254, 1282, 1314.
Significantly, Congress also explicitly included groundwater in
provisions addressing states' programs for control of nonpoint source
pollution. These provisions, including sections 208, 304(f), and 319,
together make up the portions of the Act in which Congress addressed
nonpoint source pollution--not through regulatory requirements, but
through support for state programs. Id. Sec. Sec.  1288, 1314(f), 1329.
    Section 208 of the statute is an example of a provision where
Congress was concerned about nonpoint source pollution impacting
groundwater, which it was aware could also reach surface water. That
section requires that states submit to EPA ``areawide waste treatment
management plans,'' which must include a process to control the
disposal of pollutants on land or in subsurface excavation to ``protect
both ground and surface water quality.'' Id. Sec.  1288(a), (b)(2)(K)
(emphasis added). The statute provides that areawide waste treatment
management plans shall include a process to identify mine-related
sources of pollution, such as surface and underground mine runoff, and
the plans must also set forth procedures and methods to control those
sources of runoff. Id. Sec.  1288(a), (b)(2)(G). Thus, Congress viewed
underground mine runoff, i.e., seepage to groundwater that could reach
jurisdictional surface waters, as best dealt with for CWA purposes
through an areawide waste treatment management plan for controlling
nonpoint source pollution, rather than through the regulatory program
under NPDES. See also id. Sec.  1314(f) (directing the Agency to issue
guidelines for identifying and evaluating types of nonpoint sources of
pollutants, including ``the disposal of pollutants in wells or in
subsurface excavations'').
    Congress's intent to treat releases to groundwater as analogous to
nonpoint sources, subject to control by states, is further evidenced by
analyzing section 319 of the statute, entitled ``Nonpoint source
management programs.'' Section 319 was added to the statute in 1987 and
includes requirements and related funding provisions directed at states
to control pollution from nonpoint sources to navigable waters. Id.
Sec.  1329 (codifying Water Quality Act of 1987, Pub. L. 100-4, 319,
100 Stat. 7, 52). Section 319 authorizes the Administrator to give
priority in making grants where States have implemented or are
proposing to implement programs to ``carry out ground water quality
protection activities which the Administrator determines are part of a
comprehensive nonpoint source pollution control program.'' Id. Sec.
1329(h)(5)(D). In addition, section 319 contains a groundwater-specific
grant provision in 319(i), ``Grants for Protecting Groundwater
Quality,'' for the purpose of assisting states in ``carrying out
groundwater quality protection activities'' that will ``advance the
State toward implementation of a comprehensive nonpoint source
pollution control program.'' Id. Sec.  1329(i)(1). Activities that
could be supported by the grants include activities ``to protect the
quality of groundwater and to prevent contamination of groundwater from
nonpoint sources of pollution.'' Id. (emphasis added). This and the
other provisions discussed in this section, aimed at equipping states
with information and funding needed to enact programs to protect
groundwater quality, stand in contrast to the sections of the statute,
discussed above, that set forth enforceable limitations as well as the
NPDES permitting and related provisions and contain no explicit mention
of groundwater.

IV. Comments Regarding Prior Agency Statements

    The Agency has for the first time conducted a public process,
initiated by EPA's February 2018 Federal Register notice, regarding
prior Agency statements addressing this issue, and, in conjunction with
that process, has conducted a more-substantial review of its prior
statements than previously undertaken by the Agency. As the Agency
stated in that notice, ``most of these statements were collateral to
the central focus of a rulemaking or adjudication.'' 83 FR at 7127. In
fact, most of these statements do not include any explanation for the
Agency's previous interpretation of the Act. As described above, EPA is
now clearly stating its position on this issue in a comprehensive
manner that is consistent with the text and legislative history of the
CWA.
    As commenters pointed out, there have been a range of prior
statements by the Agency that align with the legal position articulated
in this Interpretive Statement. For example, in a number of documents
discussed below, the Agency has stated simply that discharges to
groundwater are not subject to the CWA, without any qualification. The
Agency has reexamined these statements in light of what the Agency
views as the more appropriate legal question at issue here--whether the
CWA categorically excludes releases of pollutants to groundwater from
coverage under the Act--without drawing a distinction between isolated
groundwater and groundwater with a direct hydrologic connection to
jurisdictional surface waters. Viewed through this legal lens, the
statements discussed below in section (A) are highly relevant, and
supportive of the interpretation of the statute explained in this
Interpretive Statement.
    A selection of these prior statements identified by commenters are
summarized below. Many commenters observed that lack of consistent and
comprehensive direction from EPA on this issue has led to inconsistent
interpretation across the country and has created uncertainty for
regulated entities and the public. Even where the Agency stated an
interpretation, the Agency has not issued regulations or guidance
focused clearly on this issue. Thus, courts have attempted to fill this
void, but have issued conflicting decisions about whether these
releases are covered by the CWA. EPA's adoption of a precise position
on this issue and thorough explanation of the reasons why the Agency's
position is the best, if not the only, reading of the CWA will provide
certainty to EPA staff, state permitting authorities, and regulated
entities as to how EPA interprets the statute.

A. Commenters' Citation of Examples of Prior Agency Statements
Indicating Discharges to Groundwater Are Outside the Scope of the NPDES
Program

    In addressing EPA's request for comment on potential clarification
of the Agency's prior statements, commenters pointed to certain
instances in which the Agency stated that discharges to groundwater are
not subject to the CWA, without any qualification. For example, in a
1973 EPA Office of General Counsel memorandum, EPA considered whether
certain discharges to wells are subject to the NPDES program and stated
that ``[u]nder Sec.  502(12) the term `discharge of a pollutant' is
defined so as to include only discharges into navigable waters (or the
contiguous zone or the ocean). Discharges into ground waters are not
included.'' Memorandum from the U.S. EPA Acting Deputy Gen. Counsel to
the U.S. EPA Region IX Reg'l Counsel 2-3 (Dec. 13, 1973). The Agency
did not include any language indicating that, at that time, it viewed
groundwaters as distinguishable based on their connection to
jurisdictional surface waters. Notably, this memorandum was issued
close-in-time to the passage of the CWA amendments creating the NPDES
program and reflects the Agency's initial view of the statute's text,
which has not been amended in

pertinent part since that time. See also Ground Water Pollution from
Subsurface Excavations, EPA-430/9-73-012 at 131-35 (1973) (EPA report
explaining that subsurface excavations, e.g., lagoons, pits, basins,
etc., used to store or dispose of pollutants can contaminate
groundwater and that contamination can reach surface waters, without
mentioning regulation under NPDES as one of several identified methods
to address this contamination).
    Commenters also pointed out that, in its brief in Kelley on behalf
of Michigan v. United States, the United States argued that discharges
to groundwater, per se, are excluded from the CWA, and applied that
view to discharges to groundwater with a direct hydrologic connection
to jurisdictional surface waters. 618 F. Supp. 1103 (W.D. Mich. 1985).
In that case, Michigan alleged that certain toxic chemicals were
released into the ground at a U.S. Coast Guard facility, that the
chemicals contaminated the groundwater underlying the facility, and
that the plume of contamination migrated and was discharged to a
jurisdictional surface water. In its brief, the United States argued
that ``Michigan cannot make these claims under the Clean Water Act
since the Act does not regulate pollutant discharges onto soil or into
underlying ground water.'' U.S. Mem. In Supp. of Rule 12(b) Mot. & In
The Alternative for Summ. J. at 5, Kelley on behalf of Michigan v.
United States, No. G83-630, 618 F. Supp. 1103 (W.D. Mich. 1985).
    Commenters also pointed to a policy document issued during the
Clinton administration which explicitly stated that it was unclear
whether the CWA regulated discharges to groundwater with a direct
hydrologic connection to jurisdictional surface water. President
Clinton's Clean Water Initiative sought to update the CWA and stated
that it was ``presently unclear whether a discharge to the ground or to
ground water that rapidly moves into surface water through a `direct
hydrologic connection' between the point of discharge and the surface
water is subject to NPDES regulation.'' President Clinton's Clean Water
Initiative at 104, EPA 800-R-94-001 (Feb. 1994). To address this, EPA
suggested that the ``CWA should be amended to . . . [c]onfirm and
clarify that a point source discharge to ground or to ground water that
has a direct hydrological connection with surface waters is subject to
regulation as a NPDES point source discharge . . . .'' Id. at 105; see
also EPA 100-R-93-001 at 1-27, Final Comprehensive State Ground Water
Protection Guidance (Dec. 1992) (stating that ``[w]hile a number of
States have incorporated ground water discharges into their NPDES
permits and pretreatment requirements, there is no national requirement
to do so'').
    Commenters also cited to instances in permitting proceedings where
EPA indicated that NPDES permits are not required for discharges to
groundwater, without also referring to the direct hydrologic connection
theory. In a response to comments document on an NPDES pesticide
general permit, EPA explained that one commenter requested that the
permit ensure that discharges do not affect groundwater. EPA, Response
to Public Comments, EPA NPDES Pesticide General Permit at xxii (Oct.
31, 2011). EPA responded and clarified that ``the Clean Water Act's
NPDES program, under which EPA issued the [pesticide general permit],
is for the control of discharges to waters of the United States.
Generally, discharges to groundwater are not regulated under the NPDES
program; rather, discharges to groundwater are regulated under Safe
Drinking Water Act along with any additional protections that may be
incorporated in FIFRA regulations.'' Id. EPA did not qualify this
statement with any discussion of discharges to groundwater with a
direct hydrologic connection to surface water. See also EPA, Fact
Sheet, Draft General Permits for Stormwater Discharges Systems from
Small Municipal Separate Sewer Systems in Massachusetts at 18 (Sept.
30, 2014) (``NPDES permits are applicable for point source discharges
to waters of the U.S.; discharges to groundwater are not addressed in
the NPDES program and as such are not addressed by this permit.'').
    Finally, commenters also noted that EPA has not comprehensively
explained its previous interpretation in a key document that permit
writers and regulated entities frequently look to for guidance on the
NPDES program. EPA's NPDES Permit Writers' Manual (NPDES Manual)
describes the statutory and regulatory framework of the NPDES program
and examines technical considerations for developing NPDES permits.
U.S. EPA, NPDES Permit Writers' Manual vii (2010). While the NPDES
Manual is designed as a comprehensive reference on the program for
permit writers, it only briefly mentions EPA's prior interpretation:

    The CWA does not give EPA the authority to regulate ground water
quality through NPDES permits. If a discharge of pollutants to
ground water reaches waters of the United States, however, it could
be a discharge to the surface water (albeit indirectly via a direct
hydrological connection, i.e., the ground water) that needs an NPDES
permit.

    Id. at 1-7. The NPDES Manual does not elaborate on this statement
or provide guidance on how this interpretation should be implemented.

B. Commenters' Citation of Examples of Prior Agency Statements
Indicating Discharges to Groundwater With a Direct Hydrologic
Connection to Surface Water are Subject to NPDES Requirements

    As described in the February 2018 Federal Register notice
soliciting public comment on this issue, EPA has articulated its
previous position that discharges to groundwater with a direct
hydrologic connection to jurisdictional surface waters are subject to
the CWA. 83 FR at 7127 (``EPA has previously stated that pollutants
discharged from point sources that reach jurisdictional surface waters
via groundwater or other subsurface flow that has a direct hydrologic
connection to the jurisdictional water may be subject to CWA permitting
requirements.''). Commenters noted that the Agency has, in several
public documents, including rulemakings, permits, letters, and briefs
filed on EPA's behalf by the Department of Justice, indicated that
NPDES permits are required for discharges to groundwater that have a
direct hydrologic connection to jurisdictional surface waters. See,
e.g., id. (listing Agency statements in several rulemaking preambles);
Federal Appellees' Response Brief at 48, Greater Yellowstone Coal. v.
Lewis, No. 09-35729, 628 F.3d 1143 (9th Cir. 2010) (``Groundwater is
not directly regulated by the Clean Water Act . . . . Nonetheless, EPA
has consistently interpreted the Act to cover discharges into
groundwater that have a direct hydrologic connection to surface
water.''); Final General NPDES Permit for Concentrated Animal Feeding
Operations (CAFO) in Idaho ID-G-01-0000, 62 FR 20,178 (1997) (``[T]he
Clean Water Act does not give EPA the authority to regulate groundwater
quality through NPDES permits. The only situation in which groundwater
may be affected by the NPDES program is when a discharge of pollutants
to surface waters can be proven to be via groundwater . . . the permit
requirements . . . are intended to protect surface waters which are
contaminated via a groundwater (subsurface) connection.''); EPA,
Memorandum from Director, Office of Solid Waste to Waste Management
Division Directors (1995) (``In addition, such groundwater discharges
are subject

to CWA jurisdiction, based on EPA's interpretation that discharges from
point sources through groundwater where there is a direct hydrologic
connection to nearby surface waters of the United States are subject to
the prohibition against unpermitted discharges, and thus are subject to
the NPDES permitting requirements.''); EPA, In the Matter of Bethlehem
Steel Corp, UIC Appeal Nos. 85-8 & 86-13 (1989) (EPA ``declines to
exercise CWA jurisdiction over injection wells (except those that
inject into ground water with a physically and temporally direct
hydrologic connection to surface water).''). However, each of these
statements is included in preambles to rules or in permits where the
complex jurisdictional issue of releases of pollutants to groundwater
were not the central focus. In other words, these statements were
collateral to the central issues addressed in the documents in which
they are included.
    Commenters highlighted one preamble--to a proposed rule that
applied to only one category of dischargers--in which EPA discussed its
prior interpretation in some detail. In a proposed rule revising the
NPDES permit requirements and effluent limitation guidelines for CAFOs,
EPA proposed national requirements for certain CAFOs to address
potential discharges to jurisdictional surface waters via groundwater
that has a direct hydrologic connection to jurisdictional surface
waters. 66 FR 2960 (Jan. 12, 2001). In the preamble to this proposed
rule, EPA explained its interpretation of the Act as applying to these
types of discharges. Id. at 3015-20. Notably, EPA did not engage in a
detailed analysis of the Act's text, structure, and legislative history
in the 2001 preamble that has now led the Agency to the position
articulated in this Interpretive Statement. Moreover, EPA did not
finalize these proposed requirements for certain CAFOs and explained in
the preamble to the final rule that ``the factors affecting whether
such discharges are occurring . . . are so variable from site to site
that a national technology-based standard is inappropriate.'' 68 FR
7176, 7216 (Feb. 12, 2003).\3\
---------------------------------------------------------------------------

    \3\ In reviewing this regulation, the Second Circuit did note
that NPDES authorities still had the power to impose groundwater
related requirements on a case-by-case basis. Waterkeeper Alliance
v. EPA, 399 F.3d 486, 514 & n. 26, 515 (2d Cir. 2005).
---------------------------------------------------------------------------

C. Rationale for the Agency's Rejection of Commenters' Alternative
Interpretations of the CWA

    Commenters to EPA's February 2018 Federal Register notice offered
extensive legal arguments both supporting the Agency's previous direct
hydrologic connection theory, and as a basis for rejecting that theory.
Some commenters recommending the Agency retain the direct hydrologic
connection theory cited to the purpose of the statute and the
definition of ``discharge of a pollutant'' as requiring that the Agency
construe the statute as covering releases of pollutants to groundwater
that reach jurisdictional surface waters through a direct hydrologic
connection. They argued that the definition of ``discharge of a
pollutant'' is broad, and asks only whether the pollutant travels from
a point source to a jurisdictional surface water; if so, a NPDES permit
is required. Commenters in favor of the Agency's rejection of the
direct hydrologic connection theory asserted that the theory is
atextual and inconsistent with the overall statutory scheme and
legislative history of the Act. Some of these commenters offered an
alternative theory of jurisdiction that limits the scope of the CWA to
discharges of a pollutant from a point source or series of point
sources that carry the pollutant directly into the water of the United
States. In other words, they asserted that pollution must pass through
an unbroken chain of point sources for a ``discharge of a pollutant''
to have occurred, sometimes referred to as the ``terminal point
source'' theory. The Agency's position articulated herein differs from
both the direct hydrologic connection theory and the terminal point
source theory, as explained below. EPA believes its reading of the
statute--which is based on the statute as a whole and not a single
definition viewed in isolation--is most consistent with Congress's
intent. It is also carefully tailored to the specific issue of releases
of pollutants to groundwater which has generated confusion among
courts, states, regulated entities, and the public.
    Many environmental organizations that commented on EPA's February
2018 Federal Register notice urged the Agency to retain the direct
hydrologic connection theory articulated in prior Agency statements.
The Agency notes that it is maintaining several elements of that
position--that groundwater is not a water of the United States and that
groundwater is not a point source. The Agency's brief before the Ninth
Circuit in the County of Maui proceeding stated that it ``[did] not
contend that groundwater is a point source, nor [did it] contend that
groundwater is a water of the United States regulated by the Clean
Water Act.'' Brief for the United States as Amicus Curiae at 2, Cty. Of
Maui, No. 15-17447, 886 F.3d. 737.
    EPA's interpretation here departs from the position the Agency took
in the County of Maui amicus brief on the application of the definition
of ``discharge of a pollutant'' to releases of pollutants into
groundwater. The amicus brief, as well as the commenters urging the
Agency to retain the direct hydrologic connection theory, failed to
take into account Congress's unique treatment of groundwater in the CWA
when interpreting the definition of discharge of a pollutant. The
Agency's previous interpretation that a release of a pollutant from a
point source to groundwater that is conveyed to jurisdictional surface
waters could be the functional equivalent of a release to
jurisdictional surface waters thus was premised on viewing releases of
pollutants to groundwater through the NPDES point source paradigm
rather than viewing such releases in light of Congress's specific
approach to groundwater under the CWA.
    In arguing that the direct hydrologic connection theory is
consistent with the Act, the Agency's County of Maui amicus brief, like
some commenters, recognized that Congress drew a line between
regulation of discharges to groundwater and regulation of discharges to
jurisdictional surface water. EPA's amicus brief asserted that Maui
``emphatically is not a case about the regulation of groundwater'' and
``[i]nstead it is about the regulation of discharges of pollutants to
waters of the United States.'' Brief for the United States as Amicus
Curiae at 21. However, this approach takes insufficient account of the
explicit treatment of groundwater under the CWA, as reflected in the
statute's text, structure, and legislative history. In the Agency's
view, releases to groundwater should not be distinguished based on the
connection (or lack thereof) between groundwater and jurisdictional
surface waters. The text, a holistic analysis of the statute, and the
legislative history indicate that Congress's intent was to
categorically exclude groundwater from coverage of the permitting
provisions of the Act and to leave regulation of groundwater to the
states, irrespective of the type of groundwater formation and whether
it allows for discharge to jurisdictional surface waters or the
directness of such a conveyance. The direct hydrologic connection
theory upsets the careful balance that Congress struck between the
states and the federal government by pushing a category of pollutant
discharges from the state-regulated paradigm to the point source,
federally controlled, program.
    The County of Maui amicus brief, and some commenters urging that
EPA

retain the direct hydrologic connection theory, also erred by
improperly equating releases of pollutants to groundwater with releases
of pollutants from a point source to surface water that occur above
ground. The statute and its legislative history indicate that Congress
intended for all discharges to groundwater to be left to state
regulation and control, ending any potential for federal permitting
obligations once the pollutant enters groundwater, regardless of any
future contribution of any modicum of pollutants to jurisdictional
surface waters. Thus, the statute does not support analogizing
pollutants discharged from a point source to groundwater that migrate
to jurisdictional surface water to ``discharges of pollutant[s] [that]
have moved from a point source to navigable waters over the surface of
the ground or by some other means.'' Brief for the United States as
Amicus Curiae at 14, Cty. Of Maui, No. 15-17447, 886 F.3d. 737.
    As the Act's legislative history in particular demonstrates,
Congress recognized the complex and highly-localized nature of releases
to groundwater, that additional research and understanding of the
interactions between surface and groundwater are needed, and determined
that states, rather than EPA, are best positioned to regulate such
releases. Today's interpretation pertains to releases to groundwater
and thus leaves in place the Agency's case-by-case approach to
determining whether pollutant releases to jurisdictional surface waters
that do not travel through groundwater require an NPDES permit. Whether
a permit is required for such a release is necessarily a fact-specific
inquiry, informed by the point source definition and an analysis of
intervening factors. EPA and authorized states have exercised that
judgment on a case-by-case basis.\4\ It is unnecessary to posit a
categorical rule with respect to fact patterns such as those described
in footnote 4 in this Interpretive Statement because, as explained
above, the statute categorically excludes releases to and from
groundwater from the permitting requirements of the Act irrespective of
the directness of the hydrological connection.\5\
---------------------------------------------------------------------------

    \4\ For example, in the 2012 criminal case against Robert
Armstrong and RCA Oil and Gas LLC, the indictment states that the
defendant ``using a backhoe, breached the wall of the reservoir
causing the wastewater to flow into Rockcamp Run.'' United States v.
Armstrong, No. 2:12-cr-243, ECF-1, at *4 (S.D. Ohio 2013). In the
2012 criminal case against Chamness Technology Inc., Attachment A to
the Plea Agreement states that a hose from a lagoon to a rotating
water irrigator became unhooked and was observed ``discharging dark,
foamy, and odiferous liquid into a wooded draw which flowed downward
into the Palestine Creek.'' United States v. Chamness Tech., Inc.,
No. 4:14-cr-149, ECF-8-1, at *2 (S.D. Iowa 2013). In the 2014
criminal case against Freedom Industries, the Stipulation of Facts
in the Plea Agreement states that the chemical at issue leaked from
a tank, ``breached containment, including a dike wall, ran down the
riverbank and discharged into the Elk River at two discernible,
confined and discrete channels or fissures.'' United States v.
Freedom Industries, Inc., No. 2:14-cr-275, ECF-9, at *23-*24 (S.D.
W.Va. 2016). EPA's regulations for concentrated animal feeding
operations (CAFOs) prohibit discharges from manure storage lagoons
unless the lagoon is properly designed and the discharge is the
result of a 24-hour, 25-year storm. See 40 CFR part 412. EPA has
taken action against CAFOs with discharges that do not satisfy these
requirements. See United States v. Meadowvale Dairy, No. 5:16-cv-
4016, ECF-2, at *10 (N.D. Iowa 2017) (Complaint alleging that an
``inspection at Meadowvale North . . . observed manure laden process
wastewater flowing from the northern portion of [the basin] into
Unnamed Tributary East'').
    \5\ The Agency recognizes that the Sixth Circuit recently
adopted and applied a rationale similar to the terminal point source
theory. In Kentucky Waterways Alliance, the Sixth Circuit rejected
environmental groups' argument that coal ash ponds that released
pollutants into groundwater which flowed through a karst network to
a jurisdictional surface water constituted a discharge of a
pollutant under the statute. 905 F.3d 925 (6th Cir. 2018). The
environmental groups argued that the releases required a NPDES
permit, relying on both the direct hydrologic connection theory,
which the court rejected as contrary to the text and structure of
the statute, and, in the alternative, asserting that the discharge
of coal ash pollutants from the karst formation was itself a point
source discharge. On the latter claim, the court determined that
neither groundwater itself, nor groundwater flowing through a karst
network, is a point source. Id. at 932-33. The court recognized that
groundwater ``may indeed be a `conveyance,' '' but concluded that
``karst . . . is neither discernible, discrete, nor confined.'' Id.
at 933. Application of the Agency's interpretation of the Act
described herein--that all releases from a point source to
groundwater that reach a jurisdictional surface water are, as a
legal matter, categorically outside of the NPDES program--leads to
the same result as the Sixth Circuit, but based on a different
rationale. Nothing in the Kentucky Waterwaters Alliance decision
would preclude application of the Agency's interpretation within the
Sixth Circuit.
---------------------------------------------------------------------------

    Finally, the County of Maui amicus brief and some commenters
improperly rely on the broad goal of the Act to justify applying the
definition of ``discharge of a pollutant''--which exclusively addresses
point source discharges to navigable, ocean, and contiguous zone
waters--to releases of pollutants to groundwater. The brief argues that
reading the statute as excluding discharges from a point source to
groundwater ``would allow dischargers to avoid responsibility simply by
discharging pollutants from a point source into jurisdictional surface
waters through any means that was not direct.'' Brief for the United
States as Amicus Curiae at 20. This position fails to give sufficient
weight to the structure and legislative history of the statute
indicating that Congress intended in the CWA to leave regulation of all
releases of pollutants to groundwater to states, in pursuit of the
overall objective of the statute. In addition, views about the general
purpose of the Act should not override Congress's evident intent not to
regulate discharges to groundwater of any kind. As the Supreme Court
has explained, ``the textual limitations upon a law's scope are no less
a part of its `purpose' than its substantive authorizations.'' Rapanos
v. United States, 547 U.S. 715, 752 (2006) (plurality op.). Further,
excluding these releases from the scope of the NPDES program does not
equate to no protection for ground and surface waters; rather, as
described further below, states will continue to exercise their
authority over these waters as will other federal programs.
    Some commenters placed significance on a statement in the
government's County of Maui amicus brief that the direct hydrologic
connection theory was the Agency's ``longstanding position.'' Brief for
the United States as Amicus Curiae at 5. However, as the full suite of
public comments reveal, there have in fact been a range of prior
statements by the Agency, some of which align with this Interpretive
Statement, that the Agency has now considered in its analysis for the
first time. Lack of consistent and comprehensive direction from EPA on
this issue has led to inconsistent interpretation across the country
and has created uncertainty for regulated entities. Even where the
Agency has stated an interpretation, the Agency has not issued
regulations nor formal guidance focused on and explaining the basis for
the position. As noted above, this Interpretive Statement contains the
Agency's most comprehensive analysis of the CWA's text, structure,
legislative history and judicial decisions that has been lacking in
prior Agency statements on this issue. In so doing, today's statement
establishes a firm legal foundation for regulatory decisions by EPA and
states administering CWA programs and clear guidance for the courts.
    Some commenters to EPA's February 2018 Federal Register notice
highlighted certain factual scenarios, such as movement of groundwater
through a sub-surface lava tube or karst network that may resemble
formations which courts have found to be point sources. See Nat'l
Groundwater Assoc. Comments at 2 (describing certain groundwater
formations, such as ``lava tube openings, cave or conduit openings
(including karst conduit networks), or other geologic features'' that
``function as natural pipelines capable of transporting water,
effluents, and

contaminants from one point to another point and behave similarly to
manmade pipes conveying fluids''). In accordance with EPA's
interpretation of the statute, because releases of pollutants from a
point source to groundwater are categorically excluded from the scope
of the NPDES program, even if those pollutants reach jurisdictional
surface waters, it is immaterial whether pollutants subsequently travel
through groundwater in a manner resembling point source discharges.
EPA's position is that, in accordance with the best, if not the only,
interpretation of the statute, releases to groundwater are not subject
to the point source analysis, i.e., the CWA Section 301(a) prohibition,
because the statute does not cover such releases. Accordingly,
groundwater cannot be deemed a point source.
    Given the indications in both the text of the statute as well as
the legislative history that Congress intended to categorically leave
regulation of groundwater to the states, these factual distinctions are
of no legal significance. Applying the commenters' theory that releases
to groundwater are excluded because the physical characteristics of
groundwater are dissimilar to what some courts have found to be point
sources is unnecessary. The numerous provisions in the Act linking
groundwater to nonpoint source pollution, and the absence of discussion
of groundwater in any of the regulatory sections of the CWA, provide
ample support that in establishing the NPDES program Congress intended
to leave regulation of all releases of pollutants to groundwater, akin
to nonpoint source pollution, to the states.\6\
---------------------------------------------------------------------------

    \6\ While not the conclusion reached herein, some courts have
resolved these issues by deeming releases of pollutants that have
seeped into groundwater and subsequently reached surface waters to
be nonpoint source pollution. See Sierra Club v. El Paso Gold Mines,
Inc., 421 F.3d 1133, 1141 n. 4 (10th Cir. 2005) (``Groundwater
seepage that travels through fractured rock would be nonpoint source
pollution which is not subject to NPDES permitting.''); Penn
Environment v. PPG Indus., Inc., 964 F. Supp. 2d 429, 455-56 (W.D.
Pa. 2013) (``[A] discharge occurring through the migration of
groundwater and soil runoff . . . represents `nonpoint source'
pollution.'').
---------------------------------------------------------------------------

V. Case Law

    Over the 46-year history of the CWA, numerous courts have grappled
with the question that EPA addresses with this interpretation. Many
courts, including the Fifth, Sixth, and Seventh Circuit Courts of
Appeals, have looked to both the language of the Act and the
legislative history and determined that the Act excludes from its
regulatory requirements all pollutant discharges to groundwater,
regardless of whether that groundwater is hydrologically connected to
jurisdictional surface waters. Other courts, including the Fourth and
Ninth Circuit Courts of Appeals, have cited the broad, protective goals
of the Act, and applied in isolation the definition of ``discharge of a
pollutant'' to releases of pollutants from point sources to groundwater
that migrate to jurisdictional surface waters. Upon this premise, these
courts have then found that, upon meeting the courts' respective tests
for assessing the connectedness between the groundwater and
jurisdictional surface waters, such releases are subject to NPDES
requirements. The Agency believes that these interpretations departed
from the text and history of the CWA, and finds the decisions of the
Fifth and Seventh Circuit more persuasive and true to Congress's intent
in enacting the statute.
    The decisions of other circuits which have taken a different
approach than the Fourth and Ninth Circuit--taking a holistic view of
the statute and accounting for the legislative history--are
informative. In the 1977 Exxon v. Train decision, the Fifth Circuit
conducted an extensive analysis of the text, structure, and legislative
history of the statute, and held that the Act did not give EPA
authority to regulate certain releases of pollutants into groundwater.
There, EPA had asserted authority to require NPDES permits for
subsurface disposal into deep wells where an entity already had a
permit for surface discharge. 554 F.2d at 1319. The Agency did not
argue that a permit was required because disposal was an addition of a
pollutant to ``navigable waters,'' id. at 1318 n.17, but instead that
its authority was premised on the presence of an existing
jurisdictional surface water discharge, id. at 1320. In analyzing the
question of EPA's authority over deep well disposal, the court noted
that ``EPA has not argued that the wastes disposed of into wells here
do, or might, `migrate' from groundwaters back into surface waters that
concededly are within its regulatory jurisdiction,'' and thus, the
court ``express[ed] no opinion on what the result would be if that were
the state of facts.'' Id. at 1312 n.1.
    However, in holding that EPA's assertion of authority was
unsupported by the text and legislative history of the statute, the
court made two observations that are relevant to the broader question
of regulation of any discharges to groundwater. First, that the court's
construction was true ``to Congress' intention not to interfere with
existing state controls over groundwater'' generally, given the
complex, state-specific nature of groundwater regulation. And second,
that the legislative history of the Act gives not ``the slightest hint
that any Member thought the bill would grant the Administrator any
power to regulate deep-well disposal or any other form of groundwater
pollution.'' Id. at 1329 (emphasis added).
    In Rice v. Harken Exploration Co., the Fifth Circuit addressed a
factual scenario where the plaintiff's Oil Pollution Act (OPA) claim
was premised on pollutant discharges to groundwater migrating to and
polluting jurisdictional surface waters. In analyzing the merits of
that claim, the court relied on Exxon to determine whether the OPA's
requirements governing discharges to ``navigable waters of the United
States'' apply to discharges to groundwater that reach such surface
waters. There, the plaintiffs alleged that groundwater under their land
was contaminated by pollutants discharged by Harken Exploration's oil
and gas operations, and that those pollutants seeped from the
groundwater into several bodies of surface water, in violation of the
OPA. Rice v. Harken Exploration Co., 250 F.3d 264, 265-66, 270 (5th
Cir. 2001).
    Due to the lack of case law construing the term ``navigable waters
of the United States'' in the OPA context, the court's analysis focused
on cases construing the scope of the CWA, given the court's view that
the use of the term ``navigable waters'' in both statute was analogous.
Id. at 267-68 (``The legislative history of the OPA and the textually
identical definitions of `navigable waters' in the OPA and the CWA
strongly indicate that Congress generally intended the term `navigable
waters' to have the same meaning in both the OPA and the CWA.''). The
court recognized that ``[i]n Exxon, we held that the legislative
history of the CWA belied any intent to impose direct federal control
over any phase of pollution of subsurface waters.'' Id. at 269.
However, acknowledging that Exxon addressed the specific question of
CWA regulation of deep-well disposal, the court explained that ``[t]his
Court has not yet decided whether discharges into groundwater that
migrate into protected surface waters are covered'' under the CWA or
the OPA. Id. at 271. Relying on its CWA analysis in Exxon, and the
analogous absence of any indication that Congress intended to regulate
any type of groundwater under the OPA, the Fifth Circuit held that ``a
generalized assertion that covered surface waters will eventually be
affected by remote, gradual, natural seepage from the contaminated
groundwater'' was outside the scope of the OPA in order ``to respect
Congress's decision to leave the

regulation of groundwater to the States.'' Id. at 272.
    In Village of Oconomowoc Lake v. Dayton Hudson Corporation, the
Seventh Circuit squarely addressed the issue of point source discharges
that reach jurisdictional surface waters through groundwater, and
concluded that ``[n]either the Clean Water Act nor the EPA's definition
[of waters of the United States] asserts authority over ground waters,
just because these may be hydrologically connected with surface
waters.'' 24 F.3d at 965. In that case, a municipality in Wisconsin
filed a CWA citizen suit claiming that a NPDES permit was required for
a waste retention pond at a Target Stores distribution center, due to
potential seepage of waste into groundwater, which could reach
jurisdictional surface waters. Id. at 963, 965.
    In analyzing the facts before it, the Seventh Circuit explicitly
recognized the possibility that ``water from the pond will enter the
local ground waters, and thence underground aquifers that feed lakes
and streams that are part of the `waters of the United States.' '' Id.
at 965. The court also recognized, however, that ``the Clean Water Act
does not attempt to assert national power to the fullest,'' and
intentionally does not apply to all waters. Id. Based on the text of
the statute and the same compelling legislative history analyzed by the
Fifth Circuit and discussed above, the court concluded that ``[t]he
omission of ground waters from regulations is not an oversight,'' as
``Congress elected to leave the subject [of groundwater regulation] to
state law[.]'' Id. Thus, there was no cognizable CWA claim based on
discharges to ground water that may reach jurisdictional surface
waters. Id.
    Most recently, the Sixth Circuit concluded, in two related cases
addressing pollutants from coal ash ponds that seeped into groundwater
that subsequently reached jurisdictional surface waters, that the NPDES
permitting requirements do not apply to releases to groundwater. In
Kentucky Waterways Alliance v. Kentucky Utilities Co., the Sixth
Circuit held that the ``text and statutory context of the CWA'' make
clear that the statute ``does not extend to reach this form of
pollution.'' 905 F.3d at 933. In Tennessee Clean Water Network v. TVA,
the court reversed a district court decision adopting the direct
hydrologic theory, finding that ``any alleged leakages into the
groundwater are not a violation of the CWA.'' 905 F.3d at 444. The
Sixth Circuit recognized the statute's broad goal of protecting the
Nation's waters, but held that this goal cannot be pursued at all costs
``because the CWA precludes federal regulation over non-navigable-water
pollution and over nonpoint-source-pollution.'' Ky. Waterways Alliance,
905 F.3d at 937. The court explained:

    It is true that Congress sought to protect navigable waters with
the CWA . . . But it also imposed several textual limitations on the
means used to reach that goal. Had it wished to do so, Congress
could have prohibited all unpermitted discharges of all pollutants
to all waters. But it did not go so far. Instead, Congress chose to
prohibit only the discharge of pollutants to ``navigable waters from
any point source.''

    Id.; see also, e.g., Prairie Rivers Network v. Dynegy Midwest
Generation, LLC, No. 18-CV 2148, slip op. at 14 (C.D. Ill. Nov. 14,
2018) (Applying the Seventh Circuit's decision in Village of Oconomowoc
to hold that ``[i]f the discharge is made into groundwater, and the
pollutants somehow later find their way to navigable surface waters via
a discrete hydrological connection, the CWA is still not implicated,
because the offending discharge was made into groundwater, which is not
subject to the CWA''); Cape Fear River Watch v. Duke Energy Progress,
25 F. Supp. 3d 798, 810 (E.D.N.C. 2014) (``Congress did not intend for
the CWA to extend federal regulatory authority over groundwater,
regardless of whether that groundwater is eventually or somehow
`hydrologically connected' to navigable surface waters.''); Umatilla,
962 F. Supp. at 1318 (observing that ``the CWA's NPDES program should
apply to groundwater to adequately protect surface water,'' but
concluding that ``the law as written, as intended by Congress, and as
applied in Oregon for over two decades does not regulate even
hydrologically-connected groundwater''); 26 Crown Assocs., LLC v.
Greater New Haven Reg'l Water Pollution Control Auth., No. 3:15-cv-
1439, 2017 U.S. Dist. LEXIS 106989, *24 (D. Conn. 2017) (noting that
``if the Clean Water Act were to apply as a routine matter to the
discharge of pollution onto the ground that ends up seeping into the
ground water, then Congress's purpose to limit the scope of the Clean
Water Act [to point source discharges] would be easily thwarted.'').
    In contrast, the circuit and district court decisions concluding
that certain releases to groundwater are subject to NPDES requirement
have often left unaddressed the text, structure, and legislative
history of the Act pointing to Congress's intent to exclude all
discharges to groundwater from the NPDES program. The Fourth Circuit
recently held that point source releases to groundwater that reach
jurisdictional surface waters require a NPDES program in certain
instances, adopting EPA's historical direct hydrological connection
approach. Kinder Morgan, 887 F.3d at 652. In that decision, the court
did not address any of the legislative history discussed herein, nor
did the court acknowledge or address the decisions of the Fifth or
Seventh Circuit.
    Rather, in analyzing whether gasoline from a ruptured underground
pipeline that undisputedly leached from groundwater into navigable
waters required a NPDES permit, the Fourth Circuit framed its inquiry
as only whether, first, the discharge was from a point source, id. at
649-50, and second, whether there was a direct hydrological connection
between the groundwater and jurisdictional surface water, a fact-
specific determination. Id. at 651. The court cited to the broad
purpose of the Act to restore and maintain the chemical, physical, and
biological integrity of the Nation's waters, asserting that ``the
statute established a regime of zero tolerance for unpermitted
discharges of pollutants.'' Id. at 652. The court reasoned that ``if
the presence of a short distance of soil and ground water were enough
to defeat a claim, polluters easily could avoid liability under the CWA
by ensuring that all discharges pass through soil and ground water
before reaching navigable waters.'' Id. The court ultimately concluded
that ``an alleged discharge of pollutants, reaching navigable waters
located 1000 feet or less from the point source by means of ground
water with a direct hydrological connection to such navigable waters,
falls within the scope of the CWA.'' Id. at 652. In reaching this
holding,\7\ however, the court failed to consider Congress's intent,
evident from the text, structure, and legislative history of the Act,
to treat groundwater and nonpoint source discharges differently under
the Act, by leaving their regulation to states.\8\
---------------------------------------------------------------------------

    \7\ One judge dissented from the panel's holding, finding that
there was no Clean Water Act violation because the discharge of
pollutants from the pipe had been repaired, and that the continued
migration through groundwater was not a ``discharge of a pollutant''
under the Act. Kinder Morgan, 887 F.3d at 662-63 (Floyd, J.
dissenting). The dissent recognized that ``[t]his kind of migration
of pollutants through the natural movements of groundwater amounts
to nonpoint source pollution,'' and that, ``[w]hile there is no
doubt this kind of nonpoint source pollution affects the quality
[of] navigable waters, Congress deliberately chose not to place
nonpoint source pollution within the CWA's reach.'' Id.
    \8\ On September 12, 2018, in Sierra Club v. Virginia Electric
Power Co., the Fourth Circuit applied its decision in Kinder Morgan
to another fact pattern involving the addition of pollutants to
jurisdictional surface waters through groundwater. In that case, the
court recognized the precedent in Kinder Morgan that the addition of
a pollutant into navigable waters via groundwater can violate
Section 301(a) if the plaintiff can show a direct hydrological
connection between the ground water and navigable waters. 903 F.3d
403, 409 (4th Cir. 2018). The court went on to hold that a coal-
fired power plant that stored coal ash on site in a landfill and in
settling ponds was not liable under CWA Section 301(a) for
discharges of arsenic that leached from the coal ash into
groundwater and ultimately into a nearby river because the settling
ponds did not constitute ``point sources'' under the CWA. Id. at
411.

---------------------------------------------------------------------------

    Applying a similar analysis, in its decision in County of Maui, the
---------------------------------------------------------------------------
Ninth Circuit explained:

    We assume without deciding that groundwater here is neither a
point source nor a navigable water under the CWA. Hence, it does not
affect our analysis that some of our sister circuits have concluded
that groundwater is not a navigable water. We are not suggesting
that the CWA regulates all groundwater. Rather, in fidelity to the
statute, we are reinforcing that the Act regulates point source
discharges to a navigable water, and that liability may attach where
a point source discharge is conveyed to a navigable water through
groundwater.

    Cty. of Maui, 886 F.3d at 746 n.2 (citations omitted). The court
also rejected the direct hydrological connection theory espoused by the
United States as amicus, as ``it reads two words into the CWA (`direct'
and `hydrological') that are not there.'' Id. at n.3. Then, despite the
court's claim of ``fidelity to the statute,'' it ultimately determined,
without any grounding in the statute's text, that point source
discharges to groundwater that reach jurisdictional surface water are
subject to NPDES permitting requirements where they are fairly
traceable back to the point source and more than de minimis. Id. at
749. The court also left ``for another day the task of determining
when, if ever, the connection between a point source and a navigable
water is too tenuous to support liability under the CWA,'' thus
expanding the scope of the Act to cover any release of pollutants to
groundwater that reaches a jurisdictional surface water. Id.
    The Ninth Circuit stated that its decision was consistent with Rice
and Village of Oconomowoc, despite reaching the opposite conclusion
about the proper scope of the Act. The court's basis for claiming
consistency with Rice was that the Fifth Circuit, in its analysis of
the facts in that case, ``required some evidence of a link between
discharges and contamination of navigable waters.'' Id. With respect to
the Village of Oconomowoc decision, the Ninth Circuit asserted that the
Seventh Circuit ``only considered allegations of a `potential [rather
than an actual] connection between ground waters and surface waters,'
'' while the connection in its own case was undisputed. Id. However,
these are factual distinctions that should not affect the ultimate
outcome. While it is accurate that in both Rice and Village of
Oconomowoc, the courts looked to whether a connection to jurisdictional
surface waters existed, this factual inquiry and observation does not
alter the courts' ultimate interpretations of the CWA and OPA, and
their recognition of the line Congress drew with respect to pollutant
discharges to groundwater.
    In Rice, the court observed that ``[i]n light of Congress's
decision not to regulate ground waters under the CWA/OPA,'' it was
``reluctant to construe the OPA in such a way as to apply to discharges
onto land, with seepage into groundwater, that have only an indirect,
remote, and attenuated connection with an identifiable body of
`navigable waters.' '' Rice, 250 F.3d at 272. However, while the
court's reluctance was stated in relation to the facts in that case,
its ultimate interpretation was based on Congress's intent: ``[w]e must
construe the OPA in such a way as to respect Congress's decision to
leave the regulation of groundwater to the States.'' Id. (emphasis
added). Similarly, though the facts before the Seventh Circuit
addressed only a potential hydrologic connection between groundwater
and jurisdictional surface water, the court's determination was
unequivocal: ``Neither the Clean Water Act nor the EPA's definition [of
navigable waters] asserts authority over ground waters, just because
these may be hydrologically connected with surface waters.'' 24 F.3d at
965.
    The tests adopted by the Ninth and Fourth Circuits and certain
district courts create a confusing patchwork of judicial
interpretations, which the Agency has concluded lack support in the
text, structure, and legislative history of the Act. As the Supreme
Court has explained, ``an administrative agency's power to regulate in
the public interest must always be grounded in a valid grant of
authority from Congress,'' and ``in [its] anxiety to effectuate the
congressional purpose,'' an agency ``must take care not to extend the
scope of the statute beyond the point where Congress indicated it would
stop.'' See FDA v. Brown & Williamson Tobacco Corp., 529 U.S. 120, 161
(2000) (internal citations omitted). While the Ninth Circuit adopted a
``fairly traceable'' standard, rejecting EPA's prior ``direct
hydrologic connection'' test, and the Fourth Circuit imposed a 1,000
foot distance limitation, other courts have adopted other variations on
when groundwater is sufficiently connected to jurisdictional surface
water to require a NPDES permit. See, e.g., Tenn. Clean Water Network
v. TVA, 273 F. Supp. 3d 775, 827 (M.D. Tenn. 2017) (holding that ``[a]s
long as a connection [between groundwater and surface water] is shown
to be real, direct, and immediate, there is no statutory,
constitutional, or policy reason to require that every twist and turn
of its path be precisely traced''), rev'd 905 F.3d 436 (6th Cir. 2018);
McClellan Ecological Seepage Situation v. Weinberger, 707 F. Supp.
1182, 1196 (E.D. Cal. 1998) (discharges to groundwater are subject to
CWA regulation if ``the groundwater is naturally connected to surface
waters'' (emphasis added)); vacated on other grounds, McClellan
Ecological Seepage Situation v. Perry, 47 F.3d 325 (9th Cir. 1995).
    These decisions expand the Act's coverage beyond what Congress
envisioned, potentially sweeping into the scope of the statute
commonplace and ubiquitous activities such as releases from homeowners'
backyard septic systems that find their way to jurisdictional surface
waters through groundwater. The interpretations adopted by the Ninth
Circuit and Fourth Circuits both contravene Congress's intent to leave
regulation of all releases of pollutants to groundwater to states under
the CWA, and, as a practical matter, stretch the Act's carefully
constructed program of regulation of point sources beyond a point that
Congress would recognize. A holistic reading of the CWA leads to the
conclusion that releases of pollutants to groundwater are categorially
excluded from the NPDES program, and thus, Congress did not intend for
discharges from point sources that reach jurisdictional surface waters
through hydrologically connected groundwater to require a NPDES permit.
It follows that neither EPA nor the courts need engage with specific
factual questions of traceability via subsurface hydrogeology that are
currently required by certain court decisions such as County of Maui
and Kinder Morgan.

VI. Policy Considerations Supporting EPA's Interpretation

    There is sufficient legal authority to address releases of
pollutants to groundwater that subsequently reach jurisdictional
surface waters at both the state and federal level without expanding
the CWA's regulatory reach beyond what Congress envisioned. Consistent
with Congress's intent in structuring the CWA, states may regulate
groundwater quality in the manner best suited to their particular
circumstances. This interpretation will

continue to give states primacy for regulating ubiquitous groundwater
discharges from sources such as septic tanks which are known to affect
jurisdictional surface water quality in some instances. Beyond state
programs, three other federal statutes, the Safe Drinking Water Act
(``SDWA''), the Resource Conservation and Recovery Act (``RCRA''), and
the Comprehensive Environmental Response, Compensation, and Liability
Act (``CERCLA'') will continue to provide important protections for
groundwater quality, and for surface waters impacted by releases to
groundwater.

A. State Programs for Regulating Discharges to Groundwater

    The CWA establishes a regulatory floor that protects the integrity
of the Nation's navigable waters and provides states with broad
authority to adopt laws and regulations that are more protective than
the federal standards. As explained above, the Act identifies the
preservation of state authority to regulate land and water resources
within their borders as a primary aim of the Act and states that ``[i]t
is the policy of the Congress to recognize, preserve, and protect the
primary responsibilities and rights of States to prevent, reduce, and
eliminate pollution, to plan the development and use (including
restoration, preservation, and enhancement) of land and water resources
. . . .'' 33 U.S.C. 1251(b). Congress also declared as a national
policy that states manage the major construction grant program and
implement the core permitting programs authorized by the Act, among
other responsibilities. Id.
    The Act envisions that states will take an active role in
regulating discharges to waters within the state and expressly provides
states with authority to regulate beyond the Act's regulatory floor.
The CWA states that, except as expressly provided in the Act, nothing
in the Act shall ``preclude or deny the right of any State . . . to
adopt or enforce . . . any standard or limitation respecting discharges
of pollutants, or . . . any requirement respecting control or abatement
of pollution; except that . . . such State or political subdivision or
interstate agency may not adopt or enforce any effluent limitation, or
other limitation, effluent standard, prohibition, pretreatment
standard, or standard of performance which is less stringent than the
effluent limitation, or other limitation, effluent standard,
prohibition, pretreatment standard, or standard of performance under
this chapter . . . .'' Id. Sec.  1370. Congress further provided that
nothing in the Act shall be ``construed as impairing or in any manner
affecting any right or jurisdiction of the States with respect to the
waters (including boundary waters) of such States.'' Id.
    Several commenters on the Agency's February 2018 Federal Register
notice described state laws and regulations that prohibit or limit
discharges of pollutants to groundwater. For example, the Minnesota
Pollution Control Agency stated in its comments that it ``believes
Minnesota has adequate authority under state law to address discharges
outside the scope of the NPDES or UIC programs.'' Comments submitted by
Minnesota Pollution Control Agency (May 16, 2018) (Docket ID: EPA-HQ-
OW-2018-0063-0664), available at https://www.regulations.gov/document?D=EPA-HQ-OW-2018-0063-0664. MPCA further stated that ``state
permits are developed to protect groundwater as a drinking water source
[and] [t]hey also ensure that surface water quality standards will be
met.'' Id. The attorneys general of West Virginia, Alabama, Arkansas,
Colorado, Georgia, Kansas, Louisiana, Missouri, Nebraska, Nevada,
Oklahoma, South Carolina, South Dakota, Texas, and Wyoming submitted
comments describing state laws that protect intrastate water, including
groundwater, independent from the CWA. Comments submitted by West
Virginia Attorney General, et al. (May 21, 2018) (Docket ID: EPA-HQ-OW-
2018-0063-0497), available at https://www.regulations.gov/document?D=EPA-HQ-OW-2018-0063-0497.
    States that have not enacted state law-based programs that
comprehensively regulate discharges to groundwater continue to have
wide latitude to do so under state law and the CWA. See 33 U.S.C.
1251(b), 1370. EPA's position that the CWA does not regulate releases
of pollutants to groundwater, regardless of a connection to
jurisdictional surface waters, does not preclude states from regulating
these releases under state law. To the extent that there may be state
laws that limit a state's ability to regulate beyond the federal floor,
states remain free to modify these laws as they deem appropriate to
regulate discharges in the state.

B. In Other Federal Statutes, Such as SDWA, RCRA, and CERCLA, Congress
Explicitly Envisioned a Federal Role in Regulating Groundwater Quality

    In addition to state programs for regulating discharges into
groundwater, several federal statutes explicitly address regulation of
groundwater quality. Unlike in the CWA paradigm, where the federal role
is one of providing support to states to advance state regulatory
programs, in the statutes below, Congress provided for a clear federal
role. Review of the explicit provisions addressing discharges to
groundwater in these statutes makes clear that Congress can and does
directly address the issue of groundwater quality in specific federal
programs. It is also equally clear that Congress tailored those
programs to the concerns over specific practices posing an endangerment
to groundwater, while also deferring to state regulation even in those
programs. Together these statutes, along with the state programs
described above, form a mosaic of laws and regulations that provide
mechanisms and tools for EPA, states, and the public to ensure the
protection of groundwater quality, and to minimize related impacts to
surface waters.
1. SDWA
    SDWA, enacted in 1974, two years after the CWA, contains provisions
specifically aimed at preventing certain types of groundwater
contamination. This statute is one of the vehicles through which
Congress deliberately addressed the discharge of pollutants into
groundwater, while also recognizing the important role for states to
play in regulating groundwater pollution.
    Pursuant to Section 1421 of SDWA, EPA has established requirements
for state programs to regulate underground injection of fluids. See 42
U.S.C. 300h. Specifically, under that section Congress required EPA to
establish minimum requirements for effective state programs to prevent
underground injection which endangers drinking water sources, defined
under SDWA to mean underground water which supplies or can reasonably
be expected to supply any public water system. The underground
injection control (``UIC'') program under SDWA contains regulatory
requirements for four classes of wells; bans Class IV (shallow
hazardous waste) wells; and by rule authorizes most Class V wells. The
rule authorizing Class V wells requires certain reporting, and requires
that the wells are operated in ways that do not cause movement of fluid
that could endanger underground sources of drinking water, and that the
wells are properly closed when they are no longer being used. See 40
CFR 144.24, 82.
    The SDWA UIC program is one clearly designed and tailored by
Congress to address and protect groundwater quality. While SDWA is
targeted to a specific type of possible contamination, i.e., discharges
through certain types of well injection that may impact nearby drinking
water sources,

consistent with Congressional deference to states in the area of
groundwater regulation generally, it also is established primarily as a
state program. The statute expressly requires EPA to permit or provide
for ``consideration of varying geologic, hydrological, or historical
conditions in different States and different areas within a State,''
and to avoid, to the extent feasible, requirements that would
unnecessarily disrupt state injection programs. 42 U.S.C. 300h(b)(3).
2. RCRA
    Like SDWA, in RCRA Congress chose to include provisions for federal
regulation of discharges into groundwater, to protect groundwater
quality from the discharge of solid and hazardous wastes. RCRA was
enacted to ``reduce the generation of hazardous waste and to insure the
proper treatment, storage, and disposal of that waste which is
nonetheless generated, so as to minimize the present and future threat
to human health and the environment.'' Meghrig v. KFC W, Inc., 516 U.S.
479, 483 (1996). RCRA defines ``disposal'' as the ``discharge, deposit,
injection, dumping, spilling, leaking, or placing of any solid waste or
hazardous waste into or on any land or water so that such solid waste
or hazardous waste or any constituent thereof may enter the environment
or be emitted into the air or discharged into any waters, including
groundwater.'' 42 U.S.C. 6903(3) (emphasis added).
    RCRA has several provisions that expressly address groundwater
monitoring and remediation at hazardous waste treatment, storage, and
disposal (``TSD'') facilities. RCRA and EPA's implementing regulations
explicitly require groundwater monitoring for specified categories of
hazardous waste units. See id. Sec.  6924(o), (p); see also 40 CFR
264.90-264.99. In addition, the owner and/or operator of a RCRA
permitted hazardous waste facility is required to perform corrective
action for all releases of hazardous waste or constituents from any
solid waste management unit, including releases to groundwater. 42
U.S.C. 6924(u), (v); 40 CFR 264.100-264.101. Facilities that have or
should have had RCRA ``interim status'' (i.e., authorization to operate
a TSD without a permit), and some facilities that had interim status,
are subject to corrective action orders under RCRA section 3008(h). 42
U.S.C. 6928(h). Both RCRA permits and 3008(h) orders can thus address
releases resulting in contaminated groundwater.
    While these requirements may not apply to hazardous waste
``generators'' or to regulated units covered by specific exclusions or
exemptions from groundwater monitoring, see, e.g., 40 CFR 264.90,
264.101(d), RCRA also provides EPA with authority to address waste
management activities of generators, transporters, owners or operators
of treatment, storage, or disposal facilities, past or present, that
``may present an imminent and substantial endangerment to health or the
environment,'' 42 U.S.C. 6973(a). The Agency has used this authority to
address releases of contaminants into groundwater.
    RCRA non-hazardous waste facilities are generally subject to EPA
RCRA standards in 40 CFR 257 or section 258. These rules vary by unit
type, and several categories (with exceptions) are subject to specific
groundwater monitoring and corrective action requirements. These
categories include facilities that manage coal combustion residuals in
surface impoundments and landfills, as well as municipal solid waste
landfill units. See 42 U.S.C. 6949a(c); 40 CFR 257.90-257.100 (coal
combustion residuals surface impoundments and landfills); id.
Sec. Sec.  258.50-258.58 (municipal solid waste landfill units).
    EPA's RCRA regulations addressing coal combustion residuals
(``CCR'') were promulgated in 2015, with the impact of these facilities
to groundwater as a critical consideration underlying the regulations.
See 80 FR 21302, 21326 (Apr. 17, 2015) (Recognizing that
``approximately 63 percent of currently operating surface impoundments
and landfills are unlined, and thus more prone to leach contaminants
into groundwater.''). This rule specifically addresses ``groundwater
contamination from the improper management of CCR in landfills and
surface impoundments,'' and ``reflect[s] Congressional intent that
protection of groundwater be a prime objective of any new solid waste
regulations.'' Id. at 21396. To accomplish these objectives, the rule
establishes specific requirements for groundwater monitoring and
remediation. 40 CFR 257.90-257.98. If monitoring detects a
statistically significant concentration of certain constituents in
groundwater above background levels, the facility is required to
undertake further, ``targeted'' monitoring to determine whether
concentrations of specific contaminants exceed the rule's groundwater
protection standards (which, for most contaminants, are based on EPA-
established standards for drinking water). Id. Sec. Sec.  257.98,
257.95. If contamination exceeding these levels is detected, corrective
action is required. Id. Sec. Sec.  257.96-257.97. The remedy selected
as a result of the corrective action must be protective of human health
and the environment, control the sources of the releases to reduce or
eliminate further releases, remove from the environment as much of the
contamination as is feasible, and otherwise comply with all applicable
RCRA requirements. Id. Sec.  257.97(b).
    RCRA also contains corrective action requirements for releases of
regulated substances from underground storage tanks (``USTs'').
Releases from USTs can occur due to corrosion of tank material, faulty
installation, or inadequate operating and maintenance procedures.
Owners and/or operators of USTs must report releases and take
corrective action in response, including releases to groundwater. See
42 U.S.C. 6991b(c); 40 CFR part 280, subparts E & F. The term
``release'' in relation to USTs is defined in RCRA to mean ``any
spilling, leaking, emitting, discharging, escaping, leaching, or
disposing from an underground storage tank into ground water, surface
water or subsurface soils.'' 42 U.S.C. 6991(8). Unlike the CWA NPDES
provisions, this provision in RCRA explicitly defines a release as
being to groundwater as well as to surface water; where Congress
intended for a provision to relate to both, it said so clearly.
3. CERCLA
    CERCLA, also known as ``Superfund,'' is yet another example of
Congress choosing to specifically address releases of hazardous
substances to groundwater, which could reach and impact surface waters.
CERCLA provides EPA with a number of tools to address releases of
hazardous substances, pollutants and contaminants, specifically where a
``hazardous substance is released or there is a substantial threat of
such a release into the environment'' or where there is a release or
substantial threat of release of any pollutant or contaminant which may
present an imminent and substantial danger to the public health or
welfare. 42 U.S.C. 9604(a)(1). CERCLA defines ``environment'' broadly,
to include ``ground water,'' ``subsurface strata,'' as well as
``surface water.'' Id. Sec.  9601(8). Thus, under CERCLA, EPA has clear
authority to address releases into both groundwater and surface waters.
    EPA's CERCLA authorities provide a variety of mechanisms for EPA to
address hazardous substances in groundwater, through the ability to
address releases or threatened releases of hazardous substances to the
environment, issue orders, and recover costs of clean-up. See 42 U.S.C.
9604,

9606, 9607, 9621. In CERCLA, Congress explicitly provided that in
remedial actions, the clean-up level for groundwater must be that
``which at least attains Maximum Contaminant Level Goals established
under [SDWA] and water quality criteria established under . . . the
Clean Water Act'' where such goals or criteria are relevant and
appropriate under the circumstances of the release or potential
release.'' Id. Sec.  9621(d)(2)(A). EPA's National Contingency Plan
regulations implementing CERCLA also provide that ``EPA expects to
return usable ground waters to their beneficial uses wherever
practicable, within a timeframe that is reasonable given the particular
circumstances of the site.'' 40 CFR 300.430(a)(1)(iii)(F). The
determination of a ``beneficial use'' of groundwater is tied to state
and local classifications (unless the state classification is less
stringent than the EPA classification scheme), evidencing EPA's
recognition of the state-specific nature of groundwater regulation. See
Preamble to the National Contingency Plan, 55 FR 8733 (Mar. 8, 1990).