change SIP provisions, including the emission limitations within SIP
provisions, without the EPA's approval of the change through the
appropriate process. This core principle has been recognized by
multiple courts.\263\
---------------------------------------------------------------------------

    \262\ See, e.g., 40 CFR 51.104(d) and 40 CFR 51.105.
    \263\ See, e.g., Sierra Club v. TVA, 430 F.3d 1337, 1346 (11th
Cir. 2005) (``If a state wants to add, delete, or otherwise modify a
SIP provision, it must submit the proposed change to EPA for
approval''); Duquesne Light Co. v. EPA, 698 F.2d 456, 468 n.12 (D.C.
Cir. 1983) (``with certain enumerated exceptions, states do not have
the power to take any action modifying any requirement of their
SIPs, without approval from EPA''); Train v. NRDC, 421 U.S. 60, 92
(1975) (``[A] polluter is subject to existing requirements until
such time as he obtains a variance, and variances are not available
under the revision authority until they have been approved by both
the State and the Agency'').
---------------------------------------------------------------------------

    b. Comments that director's discretion provisions are an exercise
of ``enforcement discretion.''
    Comment: Several state and industry commenters asserted that the
EPA was wrong to interpret the CAA to preclude director's discretion
provisions, because such provisions are merely an exercise of a state's
traditional ``enforcement discretion.''
    Response: The EPA disagrees that a director's discretion provision
in a SIP is a valid exercise of enforcement discretion. Normally, the
concept of enforcement discretion is understood to mean that a
regulator has discretion to determine whether a specific violation

of the law by a source warrants enforcement and to determine the nature
of the remedy to seek for any such violation. The EPA of course agrees
that states have enforcement discretion of this type and that the
states may exercise such enforcement discretion as they see fit, as
does the Agency itself. However, the EPA does not agree that air
agencies may create SIP provisions that operate to eliminate the
ability of the EPA or citizens to enforce the emission limitations of
the SIP. The EPA stated clearly in the 1999 SSM Guidance that it would
not approve SIP provisions that ``would enable a State director's
decision to bar EPA's or citizens' ability to enforce applicable
requirements.'' \264\ The Agency explained at that time that such an
approach is inconsistent with the requirements of the CAA applicable to
the enforcement of SIPs.
---------------------------------------------------------------------------

    \264\ 1999 SSM Guidance at 3.
---------------------------------------------------------------------------

    The commenters' argument was that states may create SIP provisions
through which they may unilaterally decide that the emissions from a
source during an SSM event should be exempted, such that the emissions
cannot be treated as a violation by anyone. A common formulation of
such a provision provides only that the source needs to notify the
state regulatory agency that an exceedance of the emission limitations
occurred and to report that the emissions were the result of an SSM
event. If those minimal steps occur, then such provisions commonly
authorize state personnel to make an administrative decision that the
emissions in question were not a ``violation'' of the applicable
emission limitation. It may be entirely appropriate for the state
agency to elect not to bring an enforcement action based on the facts
and circumstances of a given SSM event, as a legitimate exercise of its
own enforcement discretion. However, by creating a SIP provision that
in effect authorizes the state agency to alter or suspend the otherwise
applicable SIP emission limitations unilaterally through the granting
of exemptions, the state agency would functionally be revising the SIP
with respect to the emission limitations on the source. This revision
of the applicable emission limitation would have occurred without
satisfying the requirements of the CAA for a SIP revision. As a result
of this ad hoc revision of the SIP emission limitation, the EPA and
other parties would be denied the ability to exercise their own
enforcement discretion. This is contrary to the fundamental enforcement
structure of the CAA, as provided in section 113 and section 304,
through which the EPA and other parties are authorized to bring
enforcement actions for violations of SIP emission limitations. The
state's decision not to exercise its own enforcement discretion cannot
be a basis on which to eliminate the legal rights of the EPA and other
parties to seek to enforce.
    The commenters also suggested that the director's discretion
provisions authorizing exemptions for SSM events are nonsegregable
parts of the emission limitations, i.e., that states have established
the numerical limitations at overly stringent levels specifically in
reliance on the existence of exemptions for any emissions during SSM
events. Although commenters did not provide facts to support the claims
that states set more stringent emission limitations in reliance on SSM
exemptions, in general or with respect to any specific emission
limitation, the EPA acknowledges that this could possibly have been the
case in some instances. Even if a state had taken this approach,
however, it does not follow that SIP provisions containing exemptions
for SSM events are legally permissible. Emission limitations in SIPs
must be continuous. When a state takes action in response to this SIP
call to eliminate the director's discretion provisions or otherwise to
revise them, the state may elect to overhaul the emission limitation
entirely in order to address this concern. So long as the resulting
revised SIP emission limitation is continuous and meets the
requirements of sections 110(k)(3), 110(l) and 193 and any other
sections that are germane to the type of SIP provision at issue, the
state has discretion to revise the provision as it determines best.
    c. Comments that the EPA's having previously approved a SIP
provision that authorizes the granting of variances or exemptions for
SSM events through the exercise of director's discretion renders the
provision consistent with CAA requirements.
    Comment: Several state and industry commenters argued that the
EPA's past approval of a SIP provision with a director's discretion
feature automatically means that the exercise of that authority
(whether to revise the applicable SIP emission limitations unilaterally
or to grant ad hoc exemptions from SIP emission limitations) is valid
under the CAA. One commenter asserted that because the EPA has
previously approved such a provision, ``that discretion is itself part
of the SIP, and the exercise of discretion in no way modifies SIP
requirements.'' Another commenter argued that director's discretion
provisions in SIPs are per se valid because ``[a]ll of the SIP
provisions went through a public procedure at the time of their initial
SIP approval.''
    Response: First, the EPA disagrees with the theory that a SIP
provision that includes director's discretion authority for state
personnel to modify or grant exemptions from SIP emission limitations
unilaterally is valid merely by virtue of the fact that the Agency
previously approved it. By definition, when the EPA makes a finding of
substantial inadequacy and issues a SIP call, that signifies that the
Agency previously approved a SIP provision that does not meet CAA
requirements, whether that deficiency existed at the time of the
original approval or arose later. The EPA has explicit authority under
section 110(k)(5) to require that a state eliminate or revise a SIP
provision that the Agency previously approved, whenever the EPA finds
an existing SIP provision to be substantially inadequate to meet CAA
requirements. The fact that the EPA previously approved it does not
mean that a deficient provision may remain in the SIP forever once the
Agency determines that it is deficient.
    Second, the EPA disagrees that the fact that a SIP provision
underwent public process at the time of its original creation by the
state, or at the time of its approval by EPA as part of the SIP, means
per se that the provision is consistent with CAA requirements. If an
existing SIP provision is deficient because it in effect allows a state
to revise existing SIP emission limitations without meeting the many
explicit statutory requirements for a SIP revision, the fact that the
revision that created the impermissible provision itself met the proper
procedural requirements for a SIP revision is irrelevant. Even perfect
compliance with the procedural requirements for a SIP revision at the
time of its development by the state or its approval by the EPA does
not override a substantive deficiency in the provision, nor does it
preclude the later issuance of a SIP call to correct a substantive
deficiency.
    Third, the EPA disagrees with the circular logic that because a
deficient provision with director's discretion currently exists in a
SIP, it means that exercise of the director's discretion to grant
variances or outright exemptions to sources for emissions during SSM
events is therefore consistent with CAA requirements for SIPs. An
unbounded director's discretion provision that authorizes an air agency
to alter or eliminate the otherwise applicable SIP emission limitation
functionally allows the state to revise the SIP emission

limitation without meeting the requirements for a SIP revision. In
particular, when such provisions authorize state personnel to grant
outright exemptions from the SIP emission limitations, this is
tantamount to a revision of the SIP emission limitation without
complying with the procedural and substantive requirements of the CAA
applicable to SIP revisions, including section 110(l), section 193 and
any other substantive requirements applicable to the particular SIP
emission limitation in question.
    d. Comments that director's discretion provisions in SIPs are not
prohibited by the CAA, based on recent judicial decisions.
    Comment: A number of state and industry commenters argued that
nothing in the CAA explicitly prohibits states from having SIP
provisions that include director's discretion authorization for state
personnel to modify or eliminate existing SIP provisions unilaterally,
with or without any process or within any limiting parameters. In
support of this proposition, the commenters cited recent decisions of
the Fifth Circuit in two cases concerning the EPA's disapproval of SIP
submissions from the state of Texas. Commenters argued that the EPA's
interpretation of the CAA to prohibit director's discretion provisions
in SIPs is incorrect in light of the decision of the court in Texas v.
EPA.\265\ According to commenters, the court's decision establishes
that no provision of the CAA bars such provisions. To support this
contention, one commenter quoted the court's decision extensively,
highlighting the statement, ``. . . the EPA has invoked the term
`director discretion' as if that term were an independent and
authoritative standard, and has not linked the term to the language of
the CAA.'' Similarly, the commenters cited another decision of that
court in the Luminant director's discretion case.\266\ From that
decision, commenters quoted the court's statement that the ``EPA had no
legal basis to demand `replicable' limitations on the Director's
discretion'' and the succeeding sentence, ``[n]ot once in its proposed
or final disapproval, or in its argument before this court, has the EPA
pointed to any applicable provision of the Act or its regulations that
includes a `replicability' standard.'' These commenters did not,
however, address the specific statutory provisions identified by the
EPA in the February 2013 proposal and the explanation that the Agency
provided with respect to this issue.
---------------------------------------------------------------------------

    \265\ 690 F.3d 670 (5th Cir. 2012).
    \266\ Luminant Generation Co. v. EPA, 675 F.3d 917 (5th Cir.
2012). Throughout this document, the EPA refers to this as the
Luminant director's discretion case, to distinguish it from another
Luminant case cited in this document, Luminant Generation v. EPA,
714 F.3d 841 (5th Cir. 2013).
---------------------------------------------------------------------------

    Response: The EPA disagrees that either decision cited by
commenters stands for the definitive proposition they assert, i.e.,
that director's discretion provisions in SIPs are not precluded by the
CAA. In Luminant Generation Co. v. EPA (the Luminant director's
discretion case), the court evaluated the EPA's disapproval of a SIP
submission from the state of Texas that created SIP provisions to
implement minor source permitting requirements. The EPA disapproved the
SIP submission for several reasons, one of which was based on the
director's discretion provision prohibiting use of the standard permit
for a pollution control project that the director determines raises
health concerns or threatens the NAAQS. The EPA was concerned that this
provision gave the director of the state agency discretion to make
case-by-case decisions about what the specific permit terms would be
for each source, without sufficient parameters or limitations on the
exercise of that authority. Thus, the EPA reasoned that without any
boundaries on the exercise of this authority for director's discretion,
it would be impossible for the Agency to know in advance (i.e., at the
time of acting on the SIP submission) whether the state agency would
only use that discretion in a way that would result in permits with
terms consistent with meeting CAA requirements.\267\ As the EPA
explained in the rulemaking at issue in the Luminant director's
discretion case, ``[t]here are no replicable conditions in the PCP
Standard Permit that specify how the [TCEQ] Director's discretion is to
be implemented'' for the individual case-by-case determinations.\268\
In other words, the EPA was being asked to approve a SIP provision
without knowing how the SIP provision would actually be implemented and
thus without knowing whether the results would be consistent with
applicable CAA requirements.
---------------------------------------------------------------------------

    \267\ The EPA notes that the court in the Luminant director's
discretion case focused on the fact that the director's discretion
provision included the discretion to require more of sources, if
there ``are health effects concerns or the potential to exceed the
[NAAQS],'' and the court expressed that it did not understand why
that requirement was not alone adequate to allay the Agency's
concerns. Luminant Generation Co. v. EPA, 675 F.3d 917, 929 n.11.
The EPA's primary concern, although not clearly articulated in the
rulemaking record, was that at the time of acting on the SIP
submission, there was no way for the Agency to know in advance what
the state would require of any source in the first instance, let
alone what additional things the state might require in situations
where it unilaterally decided that more might be necessary in any
given permit.
    \268\ See ``Approval and Promulgation of Implementation Plans;
Texas; Revisions to the New Source Review (NSR) State Implementation
Plan (SIP); Prevention of Significant Deterioration (PSD),
Nonattainment NSR (NNSR) for the 1997 8-Hour Ozone Standard, NSR
Reform, and a Standard Permit; Proposed rule,'' 74 FR 48467 at 48476
(September 23, 2009).
---------------------------------------------------------------------------

    As the commenters stated, the court in the Luminant director's
discretion case vacated the EPA's disapproval of the SIP submission for
several reasons, including the rejection of the Agency's argument that
it could not approve the SIP submission due to the director's
discretion feature of the SIP provisions and the resulting lack of
``replicability.'' \269\ The court found that the EPA ``failed to
identify a single provision of the Act that Texas's program violated,
let alone explain its reasons for reaching its conclusion.'' \270\ With
respect to the director's discretion issue, phrased in terms of
``replicability,'' the court found that ``[n]ot once in its proposed or
final disapproval, or in its argument before this court, has the EPA
pointed to any applicable provision of the Act or its regulations that
include a `replicability' standard.''
---------------------------------------------------------------------------

    \269\ The term ``replicable'' was taken from EPA guidance
concerning SIP provisions for attainment plans. As a ``fundamental
principle'' for SIP provisions and permits, the EPA explained that
the requirements imposed upon sources should be ``replicable'';
i.e., if they contain ``procedures for changing the rule,
interpreting the rule, or determining compliance with the rule, the
procedures are sufficiently specific and nonsubjective so that two
independent entities applying the same procedures would obtain the
same result.'' See General Preamble, 57 FR 13498 at 13568 (April 16,
1992). The EPA's intent in using this term, although not clearly
expressed in the rulemaking record, has been to indicate that a
properly constructed SIP provision with an appropriate degree of
discretion and flexibility would contain sufficient specifications
and limits on the exercise of that discretion such that the Agency
could adequately evaluate the provision at the time of its
submission. Absent sufficient limits on the discretion, the EPA
could not properly evaluate how exercise of the discretion could
affect compliance with CAA requirements.
    \270\ 675 F.3d 917, 924 (5th Cir. 2012).
---------------------------------------------------------------------------

    The EPA believes that the court's decision in the Luminant
director's discretion case is distinguishable on several important
grounds. Most importantly, the court rejected the EPA's disapproval of
the SIP submission because the Agency had not provided an adequate
explanation of why the director's discretion provision at issue was
inconsistent with the requirements of the CAA for SIP provisions. The
court emphasized the absence of any explanation in the administrative
record for the proposed or final actions that

explained which specific provisions of the CAA preclude such a
provision and why. In the February 2013 proposal and in this document,
the EPA has identified and explained the specific CAA provisions that
operate to preclude unbounded director's discretion provisions in SIPs.
    Second, the court in the Luminant director's discretion case based
its decision in part on the view that the specific director's
discretion provision at issue in that case would always result in more
stringent regulation of affected sources and always entail exercise of
the discretion in a way that would protect the NAAQS.\271\ Although its
view was not articulated clearly in the record, the EPA did not agree
with that assessment because it was not possible to evaluate in advance
how the director's discretion authority would in fact be exercised. By
contrast, the SIP provisions at issue in this action are not structured
in such a way as to allow the exercise of discretion only to make the
emission limitations more stringent. To the contrary, the director's
discretion provisions at issue in this action authorize the state
agencies to excuse sources from compliance with the otherwise
applicable SIP emission limitation during SSM events. Were the sources
seeking these discretionary exemptions meeting the applicable SIP
emission limitations, they would not need an exemption. It logically
follows that sources are seeking these exemptions because their
emissions during such events are higher than the otherwise applicable
emission limitation allows. Unlike the specific director's discretion
provision at issue in the Luminant director's discretion case, which
the court said ``can only serve to protect the NAAQS,'' the exercise of
the director's discretion authority in the SIP provisions at issue in
this action can operate to make the emission limitations less stringent
and can thereby undermine attainment and maintenance of the NAAQS,
protection of PSD increments, improvement of visibility and achievement
of other CAA objectives.
---------------------------------------------------------------------------

    \271\ Luminant Generation Co. v. EPA, 675 F.3d 917, 929 n.11
(``The provision at issues states: ``This standard permit must not
be used [if] the executive director determines there are health
effects concerns or the potential to exceed a [NAAQS] . . . until
those concerns are addressed to the satisfaction of the executive
director.'').
---------------------------------------------------------------------------

    In the Texas decision, the court evaluated the EPA's disapproval of
another SIP submission from the state of Texas that pertained to
requirements for the permitting program for minor sources. The EPA had
disapproved the submission for several different reasons, including
that the Agency believed the specific provisions at issue provided the
state agency with too much director's discretion authority to decide
what, if any, monitoring, recordkeeping and reporting requirements
should be imposed on any individual affected source in its permit. The
EPA concluded that if at the time it was evaluating the SIP provision
for approval it could not reasonably anticipate how the state agency
would exercise the discretion authorized in the provision, this made
the submission unapprovable ``for being too vague and not replicable.''
\272\ The Texas court disagreed. The court concluded that the ``degree
of discretion conferred on the TCEQ director cannot sustain the EPA's
rejection of the MRR requirements'' and that the EPA insisted on ``some
undefined limit on a director's discretion . . . based on a standard
that the CAA does not empower the EPA to enforce.'' \273\
---------------------------------------------------------------------------

    \272\ Id., 690 F.3d 670, 680.
    \273\ Id., 690 F.3d 670, 682.
---------------------------------------------------------------------------

    The EPA believes that the decision of the court in Texas v. EPA is
also distinguishable with respect to the issue of whether director's
discretion provisions are consistent with CAA requirements. First, the
Texas court based its decision primarily on the conclusion that the EPA
had failed to identify and explain the provisions of the CAA that (i)
preclude approval of SIP provisions that include unbounded director's
discretion or (ii) impose a requirement for ``replicability'' in the
exercise of director's discretion. The Texas court emphasized that
although the EPA disapproved the SIP submission for failure to meet CAA
requirements, the court found that the EPA ``is yet to explain why.''
\274\ The court further reasoned that ``the EPA has invoked the term
`director discretion' as if that term were an independent and
authoritative standard, and has not linked the term to language of the
CAA.'' \275\ Later in the opinion the court explicitly emphasized that
because it was reviewing the EPA's decisionmaking process in the
disapproval action, the court could not consider any basis for the
disapproval that was not articulated by the EPA in the rulemaking
record.\276\ The EPA is explaining its interpretation of the relevant
CAA provisions in this action.
---------------------------------------------------------------------------

    \274\ Id., 690 F.3d 670, 681.
    \275\ Id.
    \276\ Id., 690 F.3d 670, 682.
---------------------------------------------------------------------------

    Second, the Texas court also asserted its own conclusion that there
is nothing in the CAA that pertains to director's discretion in SIP
provisions or to any limitations on the exercise of such discretion. As
the court stated it:

    There is, in fact, no independent and authoritative standard in
the CAA or its implementing regulations requiring that a state
director's discretion be cabined in the way that the EPA suggests.
Therefore, the EPA's insistence on some undefined limit on a
director's discretion is . . . based on a standard that the CAA does
not empower the EPA to enforce.

However, the court reached this conclusion based upon the
administrative record before it and reiterated that it could not
consider any basis for the disapproval not articulated by the EPA in
the rulemaking record: ``We are reviewing an agency's decisionmaking
process, so the agency's action must be upheld, if at all, on the basis
articulated by the agency itself.'' \277\ Given the court's conclusion
that the EPA had failed to provide any explanation as to why the CAA
precludes director's discretion provisions in the challenged
rulemaking, the EPA believes that the court did not have the
opportunity to consider the Agency's rationale that is provided in this
action. In the February 2013 proposal and in this document, the EPA is
heeding the court's admonishment to explain in the rulemaking record
the statutory basis for the Agency's interpretation of the CAA to
prohibit director's discretion provisions that are inadequately
bounded. As explained in this action, SIP provisions that functionally
authorize a state agency to amend existing SIP emission limitations
applicable to a source unilaterally without a SIP revision are contrary
to multiple specific provisions of the CAA that pertain to SIP
revisions.
---------------------------------------------------------------------------

    \277\ Id., 690 F.3d 670, 682.
---------------------------------------------------------------------------

    Third, the Texas court emphasized that, notwithstanding the
apparent flexibility that the director's discretion provision provided
to the state agency with respect to deciding on the level of
monitoring, recordkeeping and reporting to be imposed on each source by
permit, the state's regulations explicitly prohibited relaxations of
the level of control. The court gave weight to the explicit wording of
the specific provision at issue in the case which provided that ``[t]he
existing level of control may not be lessened for any facility.'' \278\
The EPA does not agree that the specific requirements for monitoring,
recordkeeping and reporting for a given source are unrelated to the
level of control. In any event, the director's discretion provisions of
the type at issue in this

action are not limited to those that would not ``lessen'' the level of
control. To the contrary, the provisions at issue in this SIP call
action authorize state agency personnel to grant outright exemptions
from otherwise applicable SIP emission limitations during SSM events.
Thus, the EPA concludes that this portion of the reasoning of the Texas
decision would not apply to the current action.
---------------------------------------------------------------------------

    \278\ Id., 690 F.3d 670, 681.
---------------------------------------------------------------------------

    Finally, the Texas court viewed the fact that the EPA had
previously approved similar director's discretion provisions in Texas
and in Georgia as evidence that such provisions must be consistent with
CAA requirements. The EPA acknowledges that it has, from time to time,
approved SIP submissions that it should not have, whether through
failure to recognize an issue, through a misunderstanding of the facts,
through a mistaken interpretation of the law or as a result of other
such circumstances. Congress itself clearly recognized that the EPA may
occasionally take incorrect action on SIP submissions, whether
incorrect at the time of the action or as a result of later events.
Section 110(k)(5) and section 110(k)(6) both provide the EPA with
explicit authority to address past approvals of SIP submissions that
turn out to have been mistakes, whether at the time of the original
approval or as a result of later developments. The fact that the EPA
has explicit authority to issue a SIP call establishes that Congress
anticipated that the Agency may at some point approve a SIP provision
that it should not have approved because the provision is substantially
inadequate to meet CAA requirements. The EPA does not agree, however,
that its approval of a comparable SIP provision at some time in the
past negates the Agency's authority to disapprove a current SIP
submission that fails to meet applicable procedural or substantive
requirements. A challenger of the disapproval can always argue that the
inconsistency between the prior approval and the later disapproval is
evidence that the EPA is being arbitrary and capricious in its
interpretation of the statute--but at bottom the correct question is
whether the Agency is correctly interpreting the CAA in the disapproval
action currently being challenged. The fact that the EPA may have
approved another SIP submission with a comparable defect in the past
does not override the requirements of the CAA.
    Significantly, the commenters apparently make the same mistake as
the EPA did in the rulemakings at issue in the cited court decisions,
by not adequately addressing the relevant statutory provisions that
apply to SIP provisions in general and apply to revisions of existing
EPA-approved SIP provisions in particular. The commenters failed to
consider the core problem with unbounded director's discretion
provisions (i.e., that such provisions allow for unilateral revision,
relaxation or exemption from SIP emission limitations, without adequate
evaluation by the EPA and the public). As a result, the commenters do
not address the proper application of CAA provisions that govern SIP
revisions and the rationale for requiring that such SIP revisions be
reviewed by the EPA in accordance with the explicit requirements of
sections 110(k)(3), 110(l) and 193 and the other requirements germane
to the SIP provision at issue (e.g., RACT-level controls for sources
located in nonattainment areas). Indeed, the commenters did not
acknowledge the inherent problem with director's discretion provisions,
which is that such provisions have the potential to undermine SIP
emission limitations dramatically through ad hoc exemptions for excess
emissions during SSM events. By allowing for exemptions for emissions
during SSM events, these provisions also remove the incentives for
sources to be properly designed, maintained and operated so that they
will comply continuously with SIP emission limitations during all modes
of source operation.
    The EPA notes that the commenters did not acknowledge or address
the specific explanation that the Agency provided in the February 2013
proposal, including the EPA's identification of the specific statutory
provisions applicable to the revision of SIP provisions. Because these
commenters did not address the EPA's explanation of the CAA provisions
that it interprets to preclude director's discretion provisions in
SIPs, the commenters have not provided substantive comment concerning
the EPA's interpretation of the CAA on this issue. The commenters did
not dispute the EPA's interpretation of the CAA on this particular
point on statutory grounds. Rather, the commenters argued based on
their own policy preferences for an approach to director's discretion
provisions that would allow sources to receive ad hoc exemptions for
excess emissions during SSM events without the need for imposition of
an appropriate alternative SIP emission limitation, for adequate public
process for development of such an alternative SIP emission limitation
or for oversight by the EPA of any revision to the applicable SIP
emission limitations as required by the CAA.
    e. Comments opposed to the EPA's approach on the premise that there
is no ``director's discretion'' concern if the SIP provision creates a
permit program through which state officials grant sources variances or
exemptions from otherwise applicable SIP provisions.
    Comment: State commenters argued that they have imposed sufficient
boundaries on the exercise of director's discretion provisions in their
SIPs, by virtue of the fact that they grant sources variances or
exemptions from SIP emission limitations through a permitting program.
Commenters stated that their permitting program provides a more
structured process and an opportunity for public input into the
decisions concerning variances or exemptions. Moreover, they argued
that state law does provide preconditions to the granting of variances
or exemptions and thus these are not granted automatically. Based upon
these procedural requirements, the commenters contended that their
exercise of director's discretion is not ``unbounded'' as the EPA
suggested in the February 2013 proposal.
    Response: The EPA acknowledges that a permitting program can
provide a more structured and consistent process than may be provided
in a SIP for granting variances and exemptions from SIP emission
limitations and related requirements and may provide more opportunity
for public participation in those decisions. However, to the extent
that the end result of this permitting process is that a given source
is given a less stringent emission limitation than the otherwise
applicable SIP emission limitation or is given an outright exemption
from the SIP emission limitation, this result still functionally
constitutes a revision of the SIP emission limitation without meeting
the statutory requirements for a SIP revision. The EPA is not
authorized to approve a program that in essence allows a SIP revision
without compliance with the applicable statutory requirements in
sections 110(k)(3), 110(l) and 193 and any other provision that is
germane to the particular SIP emission limitation at issue.
    The EPA emphasizes that air agencies always retain the ability to
regulate sources more stringently than required by the provisions in
its SIP. Section 116 explicitly provides, with certain limited
exceptions, that states retain the authority to regulate emissions from
sources. Unless preempted from controlling a particular source, nothing
precludes states from regulating sources more stringently than
otherwise required to meet CAA requirements, so long as they meet CAA
requirements. However, if there is an applicable

emission limitation in a SIP provision (or an EPA regulation
promulgated pursuant to sections 111 or 112), section 116 explicitly
stipulates, ``such State or political subdivision may not adopt or
enforce any emission standard or emission limitation which is less
stringent than the standard or limitation under such plan or
limitation.'' Thus, a state could elect to regulate a source more
stringently than required by a specific SIP emission limitation (e.g.,
by imposing a more stringent numerical emission limitation on a
particular source or by imposing additional recordkeeping, reporting
and monitoring requirements in addition to those of the SIP provision),
but the state cannot weaken or eliminate the SIP emission limitation
(e.g., by granting exemptions from applicable SIP emission limitations
for emissions during SSM events). If a state elects to alter an
emission limitation in a SIP provision, the state must do so in
accordance with the statutory provisions applicable to SIP revisions.
    Finally, the EPA notes, if a state elects to use a permitting
process as a source-by-source means of imposing more stringent emission
limitations or additional requirements on sources, doing so can be an
acceptable approach. So long as the underlying SIP provisions are
adequate to provide the requisite level of control or requirements to
assure enforceability, a state is free to use a permitting program to
impose additional requirements above and beyond those provided in the
SIP.

D. Enforcement Discretion Provisions Pertaining to SSM Events

1. What the EPA Proposed
    In the February 2013 proposal, the EPA explained in detail that it
believes that the CAA allows states to adopt SIP provisions that impose
reasonable limits upon the exercise of enforcement discretion by air
agency personnel, so long as those provisions do not apply to the EPA
or other parties. The EPA believes that its interpretation of the CAA
with respect to enforcement discretion provisions applicable to
emissions during SSM events has been clear in the SSM Policy. In the
1982 SSM Guidance and the 1983 SSM Guidance, the EPA indicated that
states could elect to adopt SIP provisions that include criteria that
apply to the exercise of enforcement discretion by state personnel. In
the 1999 SSM Guidance, the EPA emphasized that it would not approve
such provisions if they would operate to impose the state's enforcement
discretion decisions upon the EPA or other parties because this would
be inconsistent with requirements of title I of the CAA.\279\ The EPA
acknowledged, however, that both the states and the Agency have failed
to adhere to the CAA with respect to this issue in the past, and thus
the need for this SIP call action to correct the existing deficiencies
in SIPs.
---------------------------------------------------------------------------

    \279\ See 1999 SSM Guidance at 3.
---------------------------------------------------------------------------

2. What Is Being Finalized in This Action
    In order to be clear about this important point on a going-forward
basis, the EPA is reiterating that SIP provisions cannot contain
enforcement discretion provisions that would bar enforcement by the EPA
or citizens for any violation of SIP requirements if the state elects
not to enforce.
    The EPA has previously issued a SIP call to a state specifically
for purposes of clarifying an existing SIP provision to assure that
regulated entities, regulators and courts will not misunderstand the
correct interpretation of the provision.\280\ As the EPA stated in that
action:
---------------------------------------------------------------------------

    \280\ See ``Finding of Substantial Inadequacy of Implementation
Plan; Call for Utah State Implementation Plan Revision,'' 75 FR
70888 at 70892-93 (November 19, 2010) (proposed SIP call, inter
alia, to rectify an enforcement discretion provision that in fact
appeared to bar enforcement by the EPA or citizens if the state
decided not to enforce).

. . . SIP provisions that give exclusive authority to a state to
determine whether an enforcement action can be pursued for an
exceedance of an emission limit are inconsistent with the CAA's
regulatory scheme. EPA and citizens, and any court in which they
seek to file an enforcement claim, must retain the authority to
independently evaluate whether a source's exceedance of an emission
limit warrants enforcement action.\281\
---------------------------------------------------------------------------

    \281\ See id.

    The EPA has explained in previous iterations of its SSM Policy that
a fundamental principle of the CAA with respect to SIP provisions is
that the provisions must be enforceable not only by the state but also
by the EPA and others pursuant to the citizen suit authority of section
304. Accordingly, the EPA has long stated that SIP provisions cannot be
structured such that a decision by the state not to enforce may bar
enforcement by the EPA or other parties.
3. Response to Comments
    The EPA received a small number of comments concerning the issue of
ambiguous enforcement discretion provisions in SIPs. For clarity and
ease of discussion, the EPA is responding to these comments, grouped by
issue, in this section of this document.
    a. Comments that supported the clarification of ambiguous
enforcement discretion provisions in general but opposed the EPA's
views with respect to specific SIP provisions.
    Comment: Environmental group commenters disagreed with the EPA's
proposed denial of the Petition with respect to specific enforcement
discretion provisions in the SIPs of several states. The commenters
contended that the SIP provisions are too ambiguous for courts to
recognize that the exercise of enforcement discretion by state
personnel did not preclude enforcement by the EPA or others.
    Response: The EPA disagrees with these comments. In the February
2013 proposal, the EPA explained how it reads the specific enforcement
discretion provisions in the SIPs of each of these states. The EPA
explained its evaluation of these provisions in detail. In comments
submitted on the February 2013 proposal, the states in question agreed
with the EPA's reading of the provisions. Each state agreed that these
provisions only applied to air agency personnel and not to the EPA or
any other party. Thus, the EPA believes that there should be no dispute
about the proper interpretation of these SIP provisions in any
potential future enforcement action.
    b. Comments that opposed the EPA's issuing SIP calls to obtain
state agency clarification of ambiguous enforcement discretion
provisions in SIPs.
    Comment: One commenter asserted that requiring states to correct an
ambiguous ``enforcement discretion'' provision in its SIP in order to
eliminate ``perceived ambiguity'' is a ``waste of resources.'' Although
agreeing that a state's exercise of enforcement discretion cannot
affect enforcement by the EPA or other parties under the citizen suit
provision, the commenter believed that the existence of ambiguous
provisions that could be misconstrued by a court to bar enforcement by
the EPA or others if the state elects not to enforce is not a
significant concern.
    Response: The EPA agrees with the commenter that a state's
legitimate exercise of enforcement discretion not to enforce in the
event of violations of SIP provisions should have no bearing whatsoever
on whether the EPA or others may seek to enforce for the same
violations. However, the Agency disagrees with the commenter concerning
whether some SIP provisions need to be clarified in order to assure
that this principle is adhered to in practice in enforcement actions.
For example, if on the face of an approved SIP provision the state

appears to have the unilateral authority to decide that a specific
event is not a ``violation'' or if it otherwise appears that if the
state elects not to pursue enforcement for such violation then no other
party may do so, then that SIP provision fails to meet fundamental
legal requirements for enforcement under the CAA. If the SIP provision
appears to provide that the decision of the state not to enforce for an
exceedance of the SIP emission limit bars the EPA or others from
bringing an enforcement action, then that is an impermissible
imposition of the state's enforcement discretion decisions on other
parties. The EPA has previously issued a SIP call to resolve just such
an ambiguity, and its authority to do so has been upheld.\282\ Given
that the commenter agrees with the underlying principle that a state's
exercise of enforcement discretion should have no bearing on the
exercise of enforcement authority of the EPA or citizens, the Agency
presumes that the commenter would not in fact oppose a SIP revision to
clarify that point. Moreover, the commenter would not be harmed by such
a SIP revision and would have no basis upon which to challenge it. As
the clarification of the ambiguous SIP provision should be in the
interest of all involved, including the regulated entities, the
regulators and the public, the EPA does not believe that resources used
to eliminate such ambiguities would be wasted.
---------------------------------------------------------------------------

    \282\ See ``Finding of Substantial Inadequacy of Implementation
Plan; Call for Utah State Implementation Plan Revision; Proposed
rule,'' 76 FR 21639 (April 18, 2011).
---------------------------------------------------------------------------

E. Affirmative Defense Provisions in SIPs During Any Period of
Operation

    As explained in detail in the SNPR, the EPA believes that the CAA
prohibits affirmative defense provisions in SIPs. The EPA acknowledges
that since the 1999 SSM Guidance, the Agency had interpreted the CAA to
allow narrowly tailored affirmative defense provisions. However, the
EPA's interpretation of the statute was based on arguments that have
since been rejected by the DC Circuit in the NRDC v. EPA decision. The
EPA received a substantial number of comments, both supportive and
adverse, concerning the issue of affirmative defense provisions in
SIPs. These comments and the EPA's responses to them are discussed in
section IV.D of this document.

F. Relationship Between SIP Provisions and Title V Regulations

    As the EPA explained in the February 2013 proposal, the SIP
provisions identified in the Petition highlighted an area of potential
ambiguity or conflict between the SSM Policy applicable to SIP
provisions and the EPA's regulations applicable to CAA title V
operating permit provisions. The EPA has promulgated regulations in 40
CFR part 70 applicable to state operating permit programs and in 40 CFR
part 71 applicable to federal operating permit programs.\283\ Under
each set of regulations, the EPA has provided that permits may contain,
at the permitting authority's discretion, an ``emergency provision.''
\284\
---------------------------------------------------------------------------

    \283\ See 40 CFR 70.1-70.12; 40 CFR 71.1-71.27.
    \284\ See 40 CFR 70.6(g); 40 CFR 71.6(g). The EPA also notes
that states are not required to adopt the ``emergency provision''
contained in 40 CFR 70.6(g) into their state operating permit
programs, and many states have chosen not to do so. See, e.g.,
``Clean Air Act Full Approval of Partial Operating Permit Program;
Allegheny County; Pennsylvania; Direct final rule,'' 66 FR 55112 at
55113 (November 1, 2001).
---------------------------------------------------------------------------

    The regulatory parameters applicable to such emergency provisions
in operating permits are the same for state operating permit program
regulations and the federal operating permit program regulations. The
definition of emergency is identical in the regulations for each
program.\285\
---------------------------------------------------------------------------

    \285\ See 40 CFR 70.6(g)(1); 40 CFR 71.6(g)(1).
---------------------------------------------------------------------------

    Thus, if there is an emergency event meeting the regulatory
definition, then the EPA's regulations for operating permit programs
provide for an ``affirmative defense'' to enforcement for noncompliance
with technology-based standards during the emergency event, provided
the source can demonstrate through specified forms of evidence that the
event and the permittee's actions during and after the event met a
number of specific requirements.\286\
---------------------------------------------------------------------------

    \286\ 40 CFR 70.6(g)(3); 40 CFR 71.6(g)(3).
---------------------------------------------------------------------------

    The Petitioner did not directly request that the EPA evaluate the
existing regulatory provisions applicable to operating permits in 40
CFR part 70 and 40 CFR part 71, and the EPA is not revising those
provisions in this action. In its February 2013 proposal, the EPA
explained that while it was proposing to allow narrowly drawn
affirmative defense provisions for malfunctions in SIPs, SIP provisions
that were modeled after the regulations in 40 CFR part 70 and 40 CFR
part 71 were still in conflict with the EPA's interpretation of the CAA
for SIP provisions and thus could not be allowed.\287\ However, as
explained in the SNPR, the reasoning in the subsequent NRDC v. EPA
court decision is that even narrowly defined affirmative defense
provisions in SIPs are no longer consistent with the CAA.\288\
Accordingly, regardless of whether affirmative defense provisions in
SIPs were defined more narrowly than were the provisions applicable to
operating permits under 40 CFR part 70 and 40 CFR part 71, they cannot
be included in SIPs. For these reasons, the EPA has evaluated the
specific SIP provisions identified in the Petition and is taking final
action to find substantial inadequacy and to issue a SIP call for those
SIP provisions that include features that are inappropriate for SIPs,
regardless of whether those provisions contain terms found in other
regulations.
---------------------------------------------------------------------------

    \287\ See February 2013 proposal, 78 FR 12459 at 12481-82.
    \288\ See SNPR, 79 FR 55919 at 55929-30.
---------------------------------------------------------------------------

    Additionally, we are not taking action in this rulemaking to alter
the emergency provisions found in 40 CFR part 70 and 40 CFR part 71.
Those regulations, which are applicable to title V operating permits,
may only be changed through appropriate rulemaking to revise parts 70
and 71. Further, any existing permits that contain such emergency
provisions may only be changed through established permitting
procedures. The EPA is considering whether to make changes to 40 CFR
part 70 and 40 CFR part 71, and if so, how best to make those changes.
In any such action, EPA would also intend to address the timing of any
changes to existing title V operating permits. Until that time, as part
of normal permitting process, the EPA encourages permitting authorities
to consider the discretionary nature of the emergency provisions when
determining whether to continue to include permit terms modeled on
those provisions in operating permits that the permitting authorities
are issuing in the first instance or renewing.

G. Intended Effect of the EPA's Action on the Petition

    As in the 2001 SSM Guidance, the EPA is endeavoring to be
particularly clear about the intended effect of its final action on the
Petition, of its clarifications and revisions to the SSM Policy and of
its application of the updated SSM Policy to the specific existing SIP
provisions discussed in section IX of this document.
    First, the EPA only intends its actions on the larger policy or
legal issues raised by the Petitioner to inform the public of the EPA's
current views on the requirements of the CAA with respect to SIP
provisions related to SSM events. Thus, for example, the EPA's proposed
grant of the Petitioner's request that the EPA interpret the CAA to
disallow all affirmative defense provisions is intended to convey that
the EPA has

changed its views about such provisions and that its prior views
expressed in the 1999 SSM Guidance and related rulemakings on SIP
submissions were incorrect. In this fashion, the EPA's action on the
Petition provides updated guidance relevant to future SIP actions.
    Second, the EPA only intends its actions on the specific existing
SIP provisions identified in the Petition to be applicable to those
provisions. The EPA does not intend its action on those specific
provisions to alter the current status of any other existing SIP
provisions relating to SSM events. The EPA must take later rulemaking
actions, if necessary, in order to evaluate any comparable deficiencies
in other existing SIP provisions that may be inconsistent with the
requirements of the CAA. Again, however, the EPA's actions on the
Petition provide updated guidance on the types of SIP provisions that
it believes would be consistent with CAA requirements in future
rulemaking actions.
    Third, the EPA does not intend its action on the Petition to affect
immediately any existing permit terms or conditions regarding excess
emissions during SSM events that reflect previously approved SIP
provisions. The EPA's finding of substantial inadequacy and a SIP call
for a given state provides the state time to revise its SIP in response
to the SIP call through the necessary state and federal administrative
process. Thereafter, any needed revisions to existing permits will be
accomplished in the ordinary course as the state issues new permits or
reviews and revises existing permits. The EPA does not intend the
issuance of a SIP call to have automatic impacts on the terms of any
existing permit.
    Fourth, the EPA does not intend its action on the Petition to alter
the emergency defense provisions at 40 CFR 70.6(g) and 40 CFR 71.6(g),
i.e., the title V regulations pertaining to ``emergency provisions''
permissible in title V operating permits. The EPA's regulations
applicable to title V operating permits may only be changed through
appropriate rulemaking procedures and existing permit terms may only be
changed through established permitting processes.
    Fifth, the EPA does not intend its interpretations of the
requirements of the CAA in this action on the Petition to be legally
dispositive with respect to any particular current enforcement
proceedings in which a violation of SIP emission limitations is alleged
to have occurred. The EPA handles enforcement matters by assessing each
situation, on a case-by-case basis, to determine the appropriate
response and resolution. For purposes of alleged violations of SIP
provisions, however, the terms of the applicable SIP provision will
continue to govern until that provision is revised following the
appropriate process for SIP revisions, as required by the CAA.
    Finally, the EPA does intend this final action, developed through
notice and comment, to be the statement of its most current SSM Policy,
reflecting the EPA's interpretation of CAA requirements applicable to
SIP provisions related to excess emissions during SSM events. In this
regard, the EPA is adding to and clarifying its prior statements in the
1999 SSM Guidance and making the specific changes to that guidance as
discussed in this action. Thus, this final notice for this action will
constitute the EPA's SSM Policy on a going-forward basis.

VIII. Legal Authority, Process and Timing for SIP Calls

A. SIP Call Authority Under Section 110(k)(5)

1. General Statutory Authority
    The CAA provides a mechanism for the correction of flawed SIPs,
under CAA section 110(k)(5), which provides that ``[w]henever the
Administrator finds that the applicable implementation plan for any
area is substantially inadequate to attain or maintain the relevant
national ambient air quality standards, to mitigate adequately the
interstate pollutant transport described in section [176A] of this
title or section [184] of this title, or to otherwise comply with any
requirement of [the Act], the Administrator shall require the State to
revise the plan as necessary to correct such inadequacies. The
Administrator shall notify the State of the inadequacies and may
establish reasonable deadlines (not to exceed 18 months after the date
of such notice) for the submission of such plan revisions.''
    By its explicit terms, this provision authorizes the EPA to find
that a state's existing SIP is ``substantially inadequate'' to meet CAA
requirements and, based on that finding, to ``require the State to
revise the [SIP] as necessary to correct such inadequacies.'' This type
of action is commonly referred to as a ``SIP call.'' \289\
---------------------------------------------------------------------------

    \289\ The EPA also has other discretionary authority to address
incorrect SIP provisions, such as the authority in CAA section
110(k)(6) for the EPA to correct errors in prior SIP approvals. The
authority in CAA section 110(k)(5) and CAA section 110(k)(6) can
sometimes overlap and offer alternative mechanisms to address
problematic SIP provisions. In this instance, the EPA believes that
the mechanism provided by CAA section 110(k)(5) is the better
approach, because using the mechanism of the CAA section 110(k)(6)
error correction would eliminate the affected emission limitations
from the SIP potentially leaving no emission limitation in place,
whereas the mechanism of the CAA section 110(k)(5) SIP call will
keep the provisions in place during the pendency of the state's
revision of the SIP and the EPA's action on that revision. In the
case of provisions that include impermissible automatic exemptions
or discretionary exemptions, the EPA believes that retention of the
existing SIP provision is preferable to the absence of the provision
in the interim.
---------------------------------------------------------------------------

    Significantly, CAA section 110(k)(5) explicitly authorizes the EPA
to issue a SIP call ``whenever'' the EPA makes a finding that the
existing SIP is substantially inadequate, thus providing authority for
the EPA to take action to correct existing inadequate SIP provisions
even long after their initial approval, or even if the provisions only
become inadequate due to subsequent events.\290\ The statutory
provision is worded in the present tense, giving the EPA authority to
rectify any deficiency in a SIP that currently exists, regardless of
the fact that the EPA previously approved that particular provision in
the SIP and regardless of when that approval occurred.
---------------------------------------------------------------------------

    \290\ See, e.g., Michigan v. EPA, 213 F.3d 663 (D.C. Cir. 2000)
(upholding the ``NOX SIP Call'' to states requiring
revisions to previously approved SIPs with respect to ozone
transport and section 110(a)(2)(D)(i)(I)); ``Action to Ensure
Authority To Issue Permits Under the Prevention of Significant
Deterioration Program to Sources of Greenhouse Gas Emissions:
Finding of Substantial Inadequacy and SIP Call; Final rule,'' 75 FR
77698 (December 13, 2010) (the EPA issued a SIP call to 13 states
because the endangerment finding for GHGs meant that these
previously approved SIPs were substantially inadequate because they
did not provide for the regulation of GHGs in the PSD permitting
programs of these states as required by CAA section 110(a)(2)(C) and
section 110(a)(2)(J)); ``Finding of Substantial Inadequacy of
Implementation Plan; Call for Utah State Implementation Plan
Revision,'' 74 FR 21639 (April 18, 2011) (the EPA issued a SIP call
to rectify SIP provisions dating back to 1980).
---------------------------------------------------------------------------

    It is also important to emphasize that CAA section 110(k)(5)
expressly directs the EPA to take action if the SIP provision is
substantially inadequate, not just for purposes of attainment or
maintenance of the NAAQS but also for purposes of ``any requirement''
of the CAA. The EPA interprets this reference to ``any requirement'' of
the CAA on its face to authorize reevaluation of an existing SIP
provision for compliance with those statutory and regulatory
requirements that are germane to the SIP provision at issue. Thus, for
example, a SIP provision that is intended to be an ``emission
limitation'' for purposes of a nonattainment plan for purposes of the
1997 PM2.5 NAAQS must meet various applicable statutory and
regulatory requirements, including requirements of CAA section
110(a)(2)(A) such as enforceability, the definition of the term
``emission limitation'' in CAA section 302(k), the level of emissions
control

required to constitute a ``reasonably available control measure'' in
CAA section 172(c)(1) and the other applicable statutory requirements
for the implementation of the 1997 PM2.5 NAAQS. Failure to
meet any of those applicable requirements could constitute a
substantial inadequacy suitable for a SIP call, depending upon the
facts and circumstances. By contrast, that same SIP provision should
not be expected to meet specifications of the CAA that are completely
irrelevant for its intended purpose, such as the unrelated requirement
of CAA section 110(a)(2)(G) that the state have general legal authority
comparable to CAA section 303 for emergencies.
    Use of the term ``any requirement'' in CAA section 110(k)(5) also
reflects the fact that SIP provisions could be substantially inadequate
for widely differing reasons. One provision might be substantially
inadequate because it fails to prohibit emissions that contribute to
violations of the NAAQS in downwind areas many states away. Another
provision, or even the same provision, could be substantially
inadequate because it also infringes on the legal right of members of
the public who live adjacent to the source to enforce the SIP. Thus,
the EPA has previously interpreted CAA section 110(k)(5) to authorize a
SIP call to rectify SIP inadequacies of various kinds, both broad and
narrow in terms of the scope of the SIP revisions required.\291\ On its
face, CAA section 110(k)(5) authorizes the EPA to take action with
respect to SIP provisions that are substantially inadequate to meet any
CAA requirements, including requirements relevant to the proper
treatment of excess emissions during SSM events.
---------------------------------------------------------------------------

    \291\ See, e.g., ``Finding of Significant Contribution and
Rulemaking for Certain States in the Ozone Transport Assessment
Group Region for Purposes of Reducing Regional Transport of Ozone,''
63 FR 57356 (October 27, 1998) (the EPA issued a SIP call to 23
states requiring them to rectify the failure to address interstate
transport of pollutants as required by section 110(a)(2)(D);
``Finding of Substantial Inadequacy of Implementation Plan; Call for
Utah State Implementation Plan Revision,'' 74 FR 21639 (April 18,
2011) (the EPA issued a SIP call to one state requiring it to
rectify several very specific SIP provisions).
---------------------------------------------------------------------------

    An important baseline question is whether a given deficiency
renders the SIP provision ``substantially inadequate.'' The EPA notes
that the term ``substantially inadequate'' is not defined in the CAA.
Moreover, CAA section 110(k)(5) does not specify a particular form of
analysis or methodology that the EPA must use to evaluate SIP
provisions for substantial inadequacy. Thus, under Chevron step 2, the
EPA is authorized to interpret this provision reasonably, consistent
with the provisions of the CAA. In addition, the EPA is authorized to
exercise its discretion in applying this provision to determine whether
a given SIP provision is substantially inadequate. To the extent that
the term ``substantially inadequate'' is ambiguous, the EPA believes
that it is reasonable to interpret the term in light of the specific
purposes for which the SIP provision at issue is required, and thus
whether the provision meets the fundamental CAA requirements applicable
to such a provision.
    The EPA does not interpret CAA section 110(k)(5) to require a
showing that the effect of a SIP provision that is facially
inconsistent with CAA requirements is causally connected to a
particular adverse impact. For example, the plain language of CAA
section 110(k)(5) does not require direct causal evidence that excess
emissions have occurred during a specific malfunction at a specific
source and have literally caused a violation of the NAAQS in order to
conclude that the SIP provision is substantially inadequate.\292\ A SIP
provision that purports to exempt a source from compliance with
applicable emission limitations during SSM events, contrary to the
requirements of the CAA for continuous emission limitations, does not
become legally permissible merely because there is not definitive
evidence that any excess emissions have resulted from the exemption and
have literally caused a specific NAAQS violation.\293\
---------------------------------------------------------------------------

    \292\ See US Magnesium, LLC v. EPA, 690 F.3d 1157 (10th Cir.
2012) (upholding the EPA's interpretation of section 110(k)(5) to
authorize a SIP call when the SIP provisions are inconsistent with
CAA requirements).
    \293\ The EPA notes that the GHG SIP call did not require
``proof'' that the failure of a state to address GHGs in a given PSD
permit ``caused'' particularized environmental impacts; it was
sufficient that the state's SIP failed to meet the current
fundamental legal requirements for regulation of GHGs in accordance
with the CAA. See ``Action to Ensure Authority To Issue Permits
Under the Prevention of Significant Deterioration Program to Sources
of Greenhouse Gas Emissions: Finding of Substantial Inadequacy and
SIP Call; Final rule,'' 75 FR 77698 (December 13, 2010).
---------------------------------------------------------------------------

    Similarly, the EPA does not interpret CAA section 110(k)(5) to
require direct causal evidence that a SIP provision that improperly
undermines enforceability of the SIP has resulted in a specific failed
enforcement attempt by any party. A SIP provision that has the
practical effect of barring enforcement by the EPA or through a citizen
suit, either because it would bar enforcement if an air agency elects
to grant a discretionary exemption or to exercise its own enforcement
discretion, is inconsistent with fundamental requirements of the
CAA.\294\ Such a provision also does not become legally permissible
merely because there is not definitive evidence that the state's action
literally undermined a specific attempted enforcement action by other
parties. Indeed, the EPA notes that these impediments to effective
enforcement likely have a chilling effect on potential enforcement in
general. The possibility for effective enforcement of emission
limitations in SIPs is itself an important principle of the CAA, as
embodied in CAA sections 113 and 304.
---------------------------------------------------------------------------

    \294\ See ``Finding of Substantial Inadequacy of Implementation
Plan; Call for Utah State Implementation Plan Revision,'' 74 FR
21639 at 21641 (April 18, 2011); see also US Magnesium, LLC v. EPA,
690 F.3d 1157, 1168 (10th Cir. 2012) (upholding the EPA's
interpretation of section 110(k)(5) to authorize a SIP call when the
state's SIP provision worded so that state decisions whether a given
excess emissions event constituted a violation interfered with
enforcement by the EPA or citizens for such event).
---------------------------------------------------------------------------

    The EPA's interpretation of CAA section 110(k)(5) is that the
fundamental integrity of the CAA's SIP process and structure are
undermined if emission limitations relied upon to meet CAA requirements
related to protection of public health and the environment can be
violated without potential recourse. For example, the EPA does not
believe that it is authorized to issue a SIP call to rectify an
impermissible automatic exemption provision only after a violation of
the NAAQS has occurred, or only if that NAAQS violation can be directly
linked to the excess emissions that resulted from the impermissible
automatic exemption by a particular source on a particular day. If the
SIP contains a provision that is inconsistent with fundamental
requirements of the CAA, that renders the SIP provision substantially
inadequate.
    The EPA notes that CAA section 110(k)(5) can also be an appropriate
tool to address ambiguous SIP provisions that could be read by a court
in a way that would violate the requirements of the CAA. For example,
if an existing SIP provision concerning the state's exercise of
enforcement discretion is sufficiently ambiguous that it could be
construed to preclude enforcement by the EPA or through a citizen suit
if the state elects to deem a given SSM event not a violation, then
that could render the provision substantially inadequate by interfering
with the enforcement structure of the CAA.\295\ If a court could

construe the ambiguous SIP provision to bar enforcement, then the EPA
believes that it may be appropriate to take action to eliminate that
uncertainty by requiring the state to revise the ambiguous SIP
provision. Under such circumstances, it may be appropriate for the EPA
to issue a SIP call to assure that the SIP provisions are sufficiently
clear and consistent with CAA requirements on their face.\296\
---------------------------------------------------------------------------

    \295\ Courts have on occasion interpreted SIP provisions to
limit the EPA's enforcement authority as a result of ambiguous SIP
provisions. See, e.g., U.S. v. Ford Motor Co., 736 F.Supp. 1539
(W.D. Mo. 1990) and U.S. v. General Motors Corp., 702 F.Supp. 133
(N.D. Texas 1988) (the EPA could not pursue enforcement of SIP
emission limitations where states had approved alternative emission
limitations under procedures the EPA had approved in the SIP);
Florida Power & Light Co. v. Costle, 650 F.2d 579, 588 (5th Cir.
1981) (the EPA to be accorded no discretion in interpreting state
law). The EPA does not agree with the holdings of these cases, but
they illustrate why it is reasonable to eliminate any uncertainty
about enforcement authority by requiring a state to remove or revise
a SIP provision that could be read in a way inconsistent with the
requirements of the CAA.
    \296\ See US Magnesium, LLC v. EPA, 690 F.3d 1157, 1170 (10th
Cir. 2012) (upholding the EPA's use of SIP call authority in order
to clarify language in the SIP that could be read to violate the
CAA, even if a court has not yet interpreted the language in that
way).
---------------------------------------------------------------------------

    In this instance, the Petition raised questions concerning the
adequacy of existing SIP provisions that pertain to the treatment of
excess emissions during SSM events. The SIP provisions identified by
the Petitioner generally fall into four major categories: (i) Automatic
exemptions; (ii) exemptions as a result of director's discretion; (iii)
provisions that appear to bar enforcement by the EPA or through a
citizen suit if the state decides not to enforce through exercise of
enforcement discretion; and (iv) affirmative defense provisions that
purport to limit or eliminate a court's jurisdiction to assess
liability and impose remedies for exceedances of SIP emission
limitations. The EPA believes that each of these types of SIP
deficiency potentially justifies a SIP call pursuant to CAA section
110(k)(5), if the Agency determines that a SIP call is the proper means
to rectify an existing deficiency in a SIP.
2. Substantial Inadequacy of Automatic Exemptions
    The EPA believes that SIP provisions that provide an automatic
exemption from otherwise applicable emission limitations are
substantially inadequate to meet CAA requirements. A typical SIP
provision that includes an impermissible automatic exemption would
provide that a source has to meet a specific emission limitation,
except during startup, shutdown and malfunction, and by definition any
excess emissions during such events would not be violations and thus
there could be no enforcement based on those excess emissions. The
EPA's interpretation of CAA requirements for SIP provisions has been
reiterated multiple times through the SSM Policy and actions on SIP
submissions that pertain to this issue. The EPA's longstanding view is
that SIP provisions that include automatic exemptions for excess
emissions during SSM events, such that the excess emissions during
those events are not considered violations of the applicable emission
limitations, do not meet CAA requirements. Such exemptions undermine
the attainment and maintenance of the NAAQS, protection of PSD
increments and improvement of visibility, and SIP provisions that
include such exemptions fail to meet these and other fundamental
requirements of the CAA.
    The EPA interprets CAA sections 110(a)(2)(A) and 110(a)(2)(C) to
require that SIPs contain ``emission limitations'' to meet CAA
requirements. Pursuant to CAA section 302(k), those emission
limitations must be ``continuous.'' Automatic exemptions from otherwise
applicable emission limitations thus render those limits less than
continuous as required by CAA sections 302(k), 110(a)(2)(A) and
110(a)(2)(C), thereby inconsistent with a fundamental requirement of
the CAA and thus substantially inadequate as contemplated in CAA
section 110(k)(5).
    This inadequacy has far-reaching impacts. For example, air agencies
rely on emission limitations in SIPs in order to provide for attainment
and maintenance of the NAAQS. These emission limitations are often used
by air agencies to meet various requirements including: (i) In the
estimates of emissions for emissions inventories; (ii) in the
determination of what level of emissions meets various statutory
requirements such as ``reasonably available control measures'' in
nonattainment SIPs or ``best available retrofit technology'' in
regional haze SIPs; and (iii) in critical modeling exercises such as
attainment demonstration modeling for nonattainment areas or increment
use for PSD permitting purposes.
    Because the NAAQS are not directly enforceable against individual
sources, air agencies rely on the adoption and enforcement of these
generic and specific emission limitations in SIPs in order to provide
for attainment and maintenance of the NAAQS, protection of PSD
increments and improvement of visibility, and to meet other CAA
requirements. Automatic exemption provisions for excess emissions
eliminate the possibility of enforcement for what would otherwise be
clear violations of the relied-upon emission limitations and thus
eliminate any opportunity to obtain injunctive relief that may be
needed to protect the NAAQS or meet other CAA requirements. Likewise,
the elimination of any possibility for penalties for what would
otherwise be clear violations of the emission limitations, regardless
of the conduct of the source, eliminates any opportunity for penalties
to encourage appropriate design, operation and maintenance of sources
and to encourage efforts by source operators to prevent and to minimize
excess emissions in order to protect the NAAQS or to meet other CAA
requirements. Removal of this monetary incentive to comply with the SIP
reduces a source's incentive to design, operate, and maintain its
facility to meet emission limitations at all times.
3. Substantial Inadequacy of Director's Discretion Exemptions
    The EPA believes that SIP provisions that allow discretionary
exemptions from otherwise applicable emission limitations are
substantially inadequate to meet CAA requirements for the same reasons
as automatic exemptions, but for additional reasons as well. A typical
SIP provision that includes an impermissible ``director's discretion''
component would purport to authorize air agency personnel to modify
existing SIP requirements under certain conditions, e.g., to grant a
variance from an otherwise applicable emission limitation if the source
could not meet the requirement in certain circumstances.\297\ If such
provisions are sufficiently specific, provide for sufficient public
process and are sufficiently bounded, so that it is possible to
anticipate at the time of the EPA's approval of the SIP provision how
that provision will actually be applied and the potential adverse
impacts thereof, then such a provision might meet basic CAA
requirements. In essence, if it is possible to anticipate and evaluate
in advance how the exercise of enforcement discretion could impact
compliance with other CAA requirements, then it may be possible to
determine in advance that the preauthorized exercise of director's
discretion will not interfere with other CAA requirements, such as
providing for attainment and maintenance of the

NAAQS. Most director's discretion-type provisions cannot meet this
basic test.
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    \297\ The EPA notes that problematic ``director's discretion''
provisions are not limited only to those that purport to authorize
alternative emission limitations from those required in a SIP. Other
problematic director's discretion provisions could include those
that purport to provide for discretionary changes to other
substantive requirements of the SIP, such as applicability,
operating requirements, recordkeeping requirements, monitoring
requirements, test methods, and alternative compliance methods.
---------------------------------------------------------------------------

    Unless it is possible at the time of the approval of the SIP
provision to anticipate and analyze the impacts of the potential
exercise of the director's discretion, such provisions functionally
could allow de facto revisions of the approved emission limitations
required by the SIP without complying with the process for SIP
revisions required by the CAA. Sections 110(a)(1) and (2) of the CAA
impose procedural requirements on states that seek to amend SIP
provisions. The elements of CAA section 110(a)(2) and other sections of
the CAA, depending upon the subject of the SIP provision at issue,
impose substantive requirements that states must meet in a SIP
revision. Section 110(i) of the CAA prohibits modification of SIP
requirements for stationary sources by either the state or the EPA,
except through specified processes.\298\ Section 110(k) of the CAA
imposes procedural and substantive requirements on the EPA for action
upon any SIP revision. Sections 110(l) and 193 of the CAA both impose
additional procedural and substantive requirements on the state and the
EPA in the event of a SIP revision. Chief among these many requirements
for a SIP revision would be the necessary demonstration that the SIP
revision in question would not interfere with any requirement
concerning attainment and reasonable further progress or ``any other
applicable requirement of'' the CAA to meet the requirements of CAA
section 110(l).
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    \298\ Section 110(i) of the Act states that ``no order,
suspension, plan revision or other action modifying any requirement
of an applicable implementation plan may be taken with respect to
any stationary source by the State or by the Administrator'' except
in compliance with the CAA's requirements for promulgation or
revision of a plan, with limited exceptions. See, e.g., ``Approval
and Disapproval and Promulgation of Air Quality Implementation
Plans; Colorado; Revisions to Regulation 1; Notice of proposed
rulemaking,'' 75 FR 42342 at 42344 (July 21, 2010) (proposing to
disapprove ``director discretion'' provisions as inconsistent with
CAA requirements and noting that ``[s]ection 110(i) specifically
prohibits States, except in certain limited circumstances, from
taking any action to modify any requirement of a SIP with respect to
any stationary source, except through a SIP revision''), finalized
as proposed at 76 FR 4540 (January 26, 2011); ``Corrections to the
California State Implementation Plan,'' 69 FR 67062 at 67063
(November 16, 2004) (noting that ``a state-issued variance, though
binding as a matter of State law, does not prevent EPA from
enforcing the underlying SIP provisions unless and until EPA
approves that variance as a SIP revision''); Industrial
Environmental Association v. Browner, No. 97-71117 at n.2 (9th Cir.
May 26, 2000) (noting that the EPA has consistently treated
individual variances granted under state variance provisions as
``modifications of the SIP requiring independent EPA approval'').
---------------------------------------------------------------------------

    Congress presumably imposed these many explicit requirements in
order to assure that there is adequate public process at both the air
agency and federal level for any SIP revision and to assure that any
SIP revision meets the applicable substantive requirements of the CAA.
Although no provision of the CAA explicitly addresses whether a
``director's discretion'' provision by that term is acceptable, the EPA
interprets the statute to prohibit such provisions unless they would be
consistent with the statutory and regulatory requirements that apply to
SIP revisions.\299\ A SIP provision that purports to give broad and
unbounded director's discretion to alter the existing legal
requirements of the SIP with respect to meeting emission limitations
would be tantamount to allowing a revision of the SIP without meeting
the applicable procedural and substantive requirements for such a SIP
revision. The EPA's approval of a SIP provision that purported to allow
unilateral revisions of the emission limitations in the SIP by the
state, without complying with the statutory requirements for a SIP
revision, would itself be contrary to fundamental procedural and
substantive requirements of the CAA.
---------------------------------------------------------------------------

    \299\ See, e.g., EPA's implementing regulations at 40 CFR
51.104(d) (``In order for a variance to be considered for approval
as a revision to the [SIP], the State must submit it in accordance
with the requirements of this section'') and 51.105 (``Revisions of
a plan, or any portion thereof, will not be considered part of an
applicable plan until such revisions have been approved by the
Administrator in accordance with this part.'').
---------------------------------------------------------------------------

    For this reason, the EPA has long discouraged the creation of new
SIP provisions containing an impermissible director's discretion
feature and has also taken actions to remove existing SIP provisions
that it had previously approved in error.\300\ In recent years, the EPA
has also recommended that if an air agency elects to have SIP
provisions that contain a director's discretion feature, then to be
consistent with CAA requirements the provisions must be structured so
that any resulting variances or other deviations from the emission
limitation or other SIP requirements have no federal law validity,
unless and until the EPA specifically approves that exercise of the
director's discretion as a SIP revision. Barring such a later
ratification by the EPA through a SIP revision, the exercise of
director's discretion is only valid for state (or tribal) law purposes
and would have no bearing in the event of an action to enforce the
provision of the SIP as it was originally approved by the EPA.
---------------------------------------------------------------------------

    \300\ See, e.g., ``Approval and Disapproval and Promulgation of
Air Quality Implementation Plans; Colorado; Revisions to Regulation
1,'' 76 FR 4540 (January 26, 2011) (partial disapproval of SIP
submission based on inclusion of impermissible director's discretion
provisions); ``Correction of Implementation Plans; American Samoa,
Arizona, California, Hawaii, and Nevada State Implementation Plans;
Notice of proposed rulemaking,'' 61 FR 38664 (July 25, 1996)
(proposed SIP correction to remove, pursuant to CAA section
110(k)(6), several variance provisions from American Samoa, Arizona,
California, Hawaii, and Nevada SIPs), finalized at 62 FR 34641 (June
27, 1997); ``Approval and Promulgation of Implementation Plans;
Corrections to the Arizona and Nevada State Implementation Plans;
Direct final rule,'' 74 FR 57051 (November 3, 2009) (rulemaking to
remove, pursuant to CAA section 110(k)(6), variance provisions from
Arizona and Nevada SIPs).
---------------------------------------------------------------------------

    The EPA's evaluation of the specific SIP provisions of this type
identified in the Petition indicates that none of them provides
sufficient process or sufficient bounds on the exercise of director's
discretion to be permissible. Most on their face would allow
potentially limitless exemptions from SIP requirements with potentially
dramatic adverse impacts inconsistent with the objectives of the CAA.
More importantly, however, each of the identified SIP provisions goes
far beyond the limits of what might theoretically be a permissible
director's discretion provision, by authorizing state personnel to
create case-by-case exemptions from the applicable emission limitations
or other requirements of the SIP for excess emissions during SSM
events. Given that the EPA interprets the CAA not to allow exemptions
from SIP emission limitations for excess emissions during SSM events in
the first instance, it follows that providing such exemptions through
the ad hoc mechanism of a director's discretion provision is also not
permissible and compounds the problem.
    As with automatic exemptions for excess emissions during SSM
events, a provision that allows discretionary exemptions would not meet
the statutory requirements of CAA sections 110(a)(2)(A) and
110(a)(2)(C) that require SIPs to contain ``emission limitations'' to
meet CAA requirements. Pursuant to CAA section 302(k), those emission
limitations must be ``continuous.'' Discretionary exemptions from
otherwise applicable emission limitations render those limits less than
continuous, as is required by CAA sections 110(a)(2)(A) and
110(a)(2)(C), and thereby inconsistent with a fundamental requirement
of the CAA and thus substantially inadequate as contemplated in section
CAA 110(k)(5). Such exemptions undermine the objectives of the CAA such
as protection of the NAAQS and PSD increments, and they fail to meet
other fundamental requirements of the CAA.

    In addition, discretionary exemptions undermine effective
enforcement of the SIP by the EPA or through a citizen suit, because
often there may have been little or no public process concerning the
exercise of director's discretion to grant the exemptions, or easily
accessible documentation of those exemptions, and thus even
ascertaining the possible existence of such ad hoc exemptions will
further burden parties who seek to evaluate whether a given source is
in compliance or to pursue enforcement if it appears that the source is
not. Where there is little or no public process concerning such ad hoc
exemptions, or there is inadequate access to relevant documentation of
those exemptions, enforcement by the EPA or through a citizen suit may
be severely compromised. As explained in the 1999 SSM Guidance, the EPA
does not interpret the CAA to allow SIP provisions that would allow the
exercise of director's discretion concerning violations to bar
enforcement by the EPA or through a citizen suit. The exercise of
director's discretion to exempt conduct that would otherwise constitute
a violation of the SIP would interfere with effective enforcement of
the SIP. Such provisions are inconsistent with and undermine the
enforcement structure of the CAA provided in CAA sections 113 and 304,
which provide independent authority to the EPA and citizens to enforce
SIP provisions, including emission limitations. Thus, SIP provisions
that allow discretionary exemptions from applicable SIP emission
limitations through the exercise of director's discretion are
substantially inadequate to comply with CAA requirements as
contemplated in CAA section 110(k)(5).
4. Substantial Inadequacy of Improper Enforcement Discretion Provisions
    The EPA believes that SIP provisions that pertain to enforcement
discretion but could be construed to bar enforcement by the EPA or
through a citizen suit if the air agency declines to enforce are
substantially inadequate to meet CAA requirements. A typical SIP
provision that includes an impermissible enforcement discretion
provision specifies certain parameters for when air agency personnel
should pursue enforcement action, but is worded in such a way that the
air director's decision defines what constitutes a ``violation'' of the
emission limitation for purposes of the SIP, i.e., by defining what
constitutes a violation, the air agency's own enforcement discretion
decisions are imposed on the EPA or citizens.\301\
---------------------------------------------------------------------------

    \301\ See, e.g., ``Finding of Substantial Inadequacy of
Implementation Plan; Call for Utah State Implementation Plan
Revision,'' 75 FR 70888 at 70892 (November 19, 2010). The SIP
provision at issue provided that information concerning a
malfunction ``shall be used by the executive secretary in
determining whether a violation has occurred and/or the need of
further enforcement action.'' This SIP language appeared to give the
state official exclusive authority to determine whether excess
emissions constitute a violation.
---------------------------------------------------------------------------

    The EPA's longstanding view is that SIP provisions cannot enable an
air agency's decision concerning whether or not to pursue enforcement
to bar the ability of the EPA or the public to enforce applicable
requirements.\302\ Such enforcement discretion provisions in a SIP
would be inconsistent with the enforcement structure provided in the
CAA. Specifically, the statute provides explicit independent
enforcement authority to the EPA under CAA section 113 and to citizens
under CAA section 304. Thus, the CAA contemplates that the EPA and
citizens have authority to pursue enforcement for a violation even if
the air agency elects not to do so. The EPA and citizens, and any court
in which they seek to pursue an enforcement claim for violation of SIP
requirements, must retain the authority to evaluate independently
whether a source's violation of an emission limitation warrants
enforcement action. Potential for enforcement by the EPA or through a
citizen suit provides an important safeguard in the event that the air
agency lacks resources or ability to enforce violations and provides
additional deterrence. Accordingly, a SIP provision that operates at
the air agency's election to eliminate the authority of the EPA or the
public to pursue enforcement actions would undermine the enforcement
structure of the CAA and would thus be substantially inadequate to meet
fundamental requirements in CAA sections 113 and 304.
---------------------------------------------------------------------------

    \302\ See 1999 SSM Guidance at 3.
---------------------------------------------------------------------------

5. Substantial Inadequacy of Affirmative Defense Provisions
    The EPA believes that SIP provisions that provide an affirmative
defense for excess emissions during SSM events are substantially
inadequate to meet CAA requirements. A typical SIP provision that
includes an impermissible affirmative defense operates to limit or
eliminate the jurisdiction of federal courts to assess liability or to
impose remedies in an enforcement proceeding for exceedances of SIP
emission limitations. Some affirmative defense provisions apply
broadly, whereas others are components of specific emission
limitations. Some provisions use the explicit term ``affirmative
defense,'' whereas others are structured as such provisions but do not
use this specific terminology. All of these provisions, however, share
the same legal deficiency in that they purport to alter the statutory
jurisdiction of federal courts under section 113 and section 304 to
determine liability and to impose remedies for violations of CAA
requirements, including SIP emission limitations. Accordingly, an
affirmative defense provision that operates to limit or to eliminate
the jurisdiction of the federal courts would undermine the enforcement
structure of the CAA and would thus be substantially inadequate to meet
fundamental requirements in CAA sections 113 and 304. By undermining
enforcement, such provisions also are inconsistent with fundamental CAA
requirements such as attainment and maintenance of the NAAQS,
protection of PSD increments and improvement of visibility.

B. SIP Call Process Under Section 110(k)(5)

    Section 110(k)(5) of the CAA provides the EPA with authority to
determine whether a SIP is substantially inadequate to attain or
maintain the NAAQS or otherwise comply with any requirement of the CAA.
Where the EPA makes such a determination, the EPA then has a duty to
issue a SIP call.
    In addition to providing general authority for a SIP call, CAA
section 110(k)(5) sets forth the process and timing for such an action.
First, the statute requires the EPA to notify the state of the final
finding of substantial inadequacy. The EPA typically provides notice to
states by a letter from the Assistant Administrator for the Office of
Air and Radiation to the appropriate state officials in addition to
publication of the final action in the Federal Register.
    Second, the statute requires the EPA to establish ``reasonable
deadlines (not to exceed 18 months after the date of such notice)'' for
states to submit corrective SIP submissions to eliminate the inadequacy
in response to the SIP call. The EPA proposes and takes comment on the
schedule for the submission of corrective SIP revisions in order to
ascertain the appropriate timeframe, depending on the nature of the SIP
inadequacy.
    Third, the statute requires that any finding of substantial
inadequacy and notice to the state be made public. By undertaking a
notice-and-comment rulemaking, the EPA assures that the air agencies,
affected sources and members of the public all are adequately

informed and afforded the opportunity to participate in the process.
Through the February 2013 proposal, the SNPR and this final notice, the
EPA is providing a full evaluation of the issues raised by the Petition
and has used this process as a means of giving clear and up-to-date
guidance concerning SIP provisions relevant to the treatment of excess
emissions during SSM events that is consistent with CAA requirements.
    If the state fails to submit the corrective SIP revision by the
deadline established in this final notice, CAA section 110(c)
authorizes the EPA to ``find[ ] that [the] State has failed to make a
required submission.'' \303\ Once the EPA makes such a finding of
failure to submit, CAA section 110(c)(1) requires the EPA to
``promulgate a Federal implementation plan at any time within 2 years
after the [finding] . . . unless the State corrects the deficiency, and
[the EPA] approves the plan or plan revision, before [the EPA]
promulgates such [FIP].'' Thus, if the EPA finds that the air agency
failed to submit a complete SIP revision that responds to this SIP
call, or if the EPA disapproves such SIP revision, then the EPA will
have an obligation under CAA section 110(c)(1) to promulgate a FIP no
later than 2 years from the date of the finding or the disapproval, if
the deficiency has not been corrected before that time.\304\
---------------------------------------------------------------------------

    \303\ CAA section 110(c)(1)(A).
    \304\ The 2-year deadline does not necessarily apply to FIPs
following disapproval of a tribal implementation plan.
---------------------------------------------------------------------------

    The finding of failure to submit a revision in response to a SIP
call or the EPA's disapproval of that corrective SIP revision can also
trigger sanctions under CAA section 179. If a state fails to submit a
complete SIP revision that responds to a SIP call, CAA section 179(a)
provides for the EPA to issue a finding of state failure. Such a
finding starts mandatory 18-month and 24-month sanctions clocks. The
two sanctions that apply under CAA section 179(b) are the 2-to-1
emission offset requirement for all new and modified major sources
subject to the nonattainment NSR program and restrictions on highway
funding. However, section 179 leaves it to the EPA to decide the order
in which these sanctions apply. The EPA issued an order of sanctions
rule in 1994 but did not specify the order of sanctions where a state
fails to submit or submits a deficient SIP revision in response to a
SIP call.\305\ In the February 2013 proposal, as the EPA has done in
other SIP calls, the EPA proposed that the 2-to-1 emission offset
requirement will apply for all new sources subject to the nonattainment
NSR program beginning 18 months following such finding or disapproval
unless the state corrects the deficiency before that date. The EPA
proposed that the highway funding restrictions sanction will also apply
beginning 24 months following such finding or disapproval unless the
state corrects the deficiency before that date. Finally, the EPA
proposed that the provisions in 40 CFR 52.31 regarding staying the
sanctions clock and deferring the imposition of sanctions would also
apply. In this action, the EPA is finalizing the order of sanctions as
proposed in the February 2013 proposal and finalizing its decision
concerning the application of 40 CFR 52.31.
---------------------------------------------------------------------------

    \305\ See ``Selection of Sequence of Mandatory Sanctions for
Findings Made Pursuant to Section 179 of the Clean Air Act,'' 59 FR
39832 (August 4, 1994), codified at 40 CFR 52.31.
---------------------------------------------------------------------------

    Mandatory sanctions under CAA section 179 generally apply only in
nonattainment areas. By its definition, the emission offset sanction
applies only in areas required to have a part D NSR program, i.e.,
areas designated nonattainment. Section 179(b)(1) expressly limits the
highway funding restriction to nonattainment areas. Additionally, the
EPA interprets the section 179 sanctions to apply only in the area or
areas of the state that are subject to or required to have in place the
deficient SIP and for the pollutant or pollutants that the specific SIP
element addresses. For example, if the deficient provision applies
statewide and applies for all NAAQS pollutants, then the mandatory
sanctions would apply in all areas designated nonattainment for any
NAAQS within the state. In this case, the EPA will evaluate the
geographic scope of potential sanctions at the time it makes a
determination that the air agency has failed to make a complete SIP
submission in response to this SIP call, or at the time it disapproves
such a SIP submission. The appropriate geographic scope for sanctions
may vary depending upon the SIP provisions at issue.

C. SIP Call Timing Under Section 110(k)(5)

    When the EPA finalizes a finding of substantial inadequacy and a
SIP call for any state, CAA section 110(k)(5) requires the EPA to
establish a SIP submission deadline by which the state must make a SIP
submission to rectify the identified deficiency. Pursuant to CAA
section 110(k)(5), the EPA has authority to set a SIP submission
deadline that is up to 18 months from the date of the final finding of
inadequacy.
    The EPA proposed to establish a date 18 months from the date of
promulgation of the final finding for the state to respond to the SIP
call. After further evaluation of this issue and consideration of
comments on the proposed SIP call, the EPA has decided to finalize the
proposed schedule. Thus, the SIP submission deadline for each of the
states subject to this SIP call will be November 22, 2016. Thereafter,
the EPA will review the adequacy of that new SIP submission in
accordance with the CAA requirements of sections 110(a), 110(k), 110(l)
and 193, including the EPA's interpretation of the CAA reflected in the
SSM Policy as clarified and updated through this rulemaking.
    The EPA is providing the maximum time permissible under the CAA for
a state to respond to a SIP call. The EPA believes that it is
appropriate to provide states with the full 18 months authorized under
CAA section 110(k)(5) in order to allow states sufficient time to make
SIP revisions following their own SIP development process. During this
time, the EPA recognizes, an affected state will need to revise its
state regulations, provide for public input, process the SIP revision
through the state's own procedures and submit the SIP revision to the
EPA. Such a schedule will allow for the necessary SIP development
process to correct the deficiencies, yet still achieve the necessary
SIP improvements as expeditiously as practicable. There may be
exceptions, particularly in states that have adopted especially time-
consuming procedures for adoption and submission of SIP revisions. The
EPA acknowledges that the longstanding existence of many of the
provisions at issue, such as automatic exemptions for SSM events, may
have resulted in undue reliance on them as a compliance mechanism by
some sources. As a result, development of appropriate SIP revisions may
entail reexamination of the applicable emission limitations themselves,
and this process may require the maximum time allowed by the CAA. For
example, if circumstances do not allow the state to develop alternative
emission limitations within that time, the state may find it necessary
to remove the automatic exemptions in an initial responsive SIP
revision and establish alternative emission limitations in a later SIP
revision. Nevertheless, the EPA encourages the affected states to make
the necessary revisions in as timely a fashion as possible and
encourages the states to work with the respective EPA Regional

Office as they develop the SIP revisions. The EPA intends to review and
act upon the SIP submissions as promptly as resources will allow, in
order to correct these deficiencies in as timely a manner as possible.
Recent experience with several states that elected to correct the
deficiencies identified in the February 2013 proposal in advance of
this final action suggests that these SIP revisions can be addressed
efficiently through cooperation between the air agencies and the EPA.
    The EPA notes that the SIP call for affected states finalized in
this action is narrow and applies only to the specific SIP provisions
determined to be inconsistent with the requirements of the CAA. To the
extent that a state is concerned that elimination of a particular
aspect of an existing emission limitation, such as an impermissible
exemption, will render that emission limitation more stringent than the
state originally intended and more stringent than needed to meet the
CAA requirements it was intended to address, the EPA anticipates that
the state will revise the emission limitation accordingly, but without
the impermissible exemption or other feature that necessitated the SIP
call. With adequate justification, this SIP revision might, e.g.,
replace a numerical emission limitation with an alternative control
method (design, equipment, work practice or operational standard) as a
component of the emission limitation applicable during startup and/or
shutdown periods.
    The EPA emphasizes that its authority under CAA section 110(k)(5)
does not extend to requiring a state to adopt a particular control
measure in its SIP revision in response to the SIP call. Under
principles of cooperative federalism, the CAA vests air agencies with
substantial discretion in how to develop SIP provisions, so long as the
provisions meet the legal requirements and objectives of the CAA.\306\
Thus, the inclusion of a SIP call to a state in this action should not
be misconstrued as a directive to the state to adopt a particular
control measure. The EPA is merely requiring that affected states make
SIP revisions to remove or revise existing SIP provisions that fail to
comply with fundamental requirements of the CAA. The states retain
discretion to remove or revise those provisions as they determine best,
so long as they bring their SIPs into compliance with the requirements
of the CAA.\307\ Through this rulemaking action, the EPA is
reiterating, clarifying and updating its interpretations of the CAA
with respect to SIP provisions that apply to emissions from sources
during SSM events in order to provide states with comprehensive
guidance concerning such provisions.
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    \306\ See Virginia v. EPA, 108 F.3d 1397 (D.C. Cir. 1997) (SIP
call remanded and vacated because, inter alia, the EPA had issued a
SIP call that required states to adopt a particular control measure
for mobile sources).
    \307\ Notwithstanding the latitude states have in developing SIP
provisions, the EPA is required to assure that states meet the basic
legal criteria for SIPs. See Michigan v. EPA, 213 F.3d 663, 686
(D.C. Cir. 2000) (upholding NOx SIP call because, inter
alia, the EPA was requiring states to meet basic legal requirement
that SIPs comply with section 110(a)(2)(D), not dictating the
adoption of a particular control measure).
---------------------------------------------------------------------------

    Finally, the EPA notes that under section 553 of the Administrative
Procedure Act, 5 U.S.C. 553(d), an agency rule should not be
``effective'' less than 30 days after its publication, unless certain
exceptions apply including an exception for ``good cause.'' In this
action, the EPA is simultaneously taking final action on the Petition,
issuing its revised SSM Policy guidance to states for SIP provisions
applicable to emissions during SSM events and issuing a SIP call to 36
states for specific existing SIP provisions that it has determined to
be substantially inadequate to meet CAA requirements. Section 110(k)(5)
provides that the EPA must notify states affected by a SIP call and
must establish a deadline for SIP submissions by affected states in
response to a SIP call not to exceed 18 months after the date of such
notification. The EPA is notifying affected states of this final SIP
call action on May 22, 2015. Thus, regardless of the effective date of
this action, the deadline for submission of SIP revisions to address
the specific SIP provisions that the EPA has identified as
substantially inadequate will be November 22, 2016. In addition, the
EPA concludes that there is good cause for this final action to be
effective on May 22, 2015, the day upon which the EPA provided notice
to the states, because any delayed effective date would be unnecessary
given that CAA section 110(k)(5) explicitly provides that the deadline
for submission of the required SIP revisions runs from the date of
notification to the affected states, not from some other date, and
shall not exceed 18 months.

D. Response to Comments Concerning SIP Call Authority, Process and
Timing

    The EPA received a wide range of comments on the February 2013
proposal and the SNPR questioning the scope of the Agency's authority
to issue this SIP call action under section 110(k)(5), the process
followed by EPA for this SIP call action, or the timing that the EPA
provided for response to this SIP call action. Although there were
numerous comments on these general topics, the majority of the comments
raised the same questions and made similar arguments (e.g., that the
EPA has an obligation under section 110(k)(5) to ``prove'' not only
that an exemption for SSM events in a SIP emission limitation is
contrary to the explicit legal requirements of the CAA but also that
this illegal exemption ``caused'' a specific violation of the NAAQS at
a particular monitor on a particular day). For clarity and ease of
discussion, the EPA is responding to these overarching comments,
grouped by topic, in this section of this document.
    1. Comments that section 110(k)(5) requires the EPA to ``prove
causation'' to have authority to issue a SIP call.
    Comment: Numerous state and industry commenters argued that the EPA
has no authority to issue a SIP call with respect to a given SIP
provision unless and until the Agency first proves definitively that
the provision has caused a specific harm, such as a specific violation
of the NAAQS in a specific area. These commenters generally focused
upon the ``attainment and maintenance'' clause of section 110(k)(5) and
did not address the ``comply with any requirement of'' the CAA clause.
    For example, many industry commenters opposed the EPA's
interpretation of section 110(k)(5) on the grounds that the Agency had
failed to provide a specific technical analysis ``proving'' how the SIP
provisions failed to provide for attainment or maintenance of the
NAAQS. For areas attaining the NAAQS, commenters asserted that there
should be a presumption that existing SIP provisions are adequate if
they have resulted in attainment of the NAAQS. For areas violating the
NAAQS, commenters claimed that the EPA is required to conduct a
technical analysis to determine if there is a ``nexus between the
provisions that are the subject of its SSM SIP Call Proposal and the
specific pollutants for which attainment has not been achieved.'' Other
industry commenters argued that in order to have authority to issue a
SIP call, the EPA must prove through a technical analysis that a given
SIP provision ``is'' substantially inadequate, not that it ``may be.''
These commenters claimed that the EPA has not shown how any of the SIP
provisions at issue in this action ``threatens the NAAQS, fails to
sufficiently mitigate interstate transport, or comply with any other

CAA requirement.'' Many industry commenters questioned whether exempt
emissions during SSM events pose any attainment-related concerns,
making assertions such as: ``[i]nfrequent malfunction, startup and
shutdown events at a limited number of stationary sources are likely to
have no effect on attainment.''
    Many state commenters made similar arguments, based on the specific
attainment or nonattainment status of areas in their respective states.
For example, one state commenter claimed that the EPA failed to make
required technical findings that the specific provisions the Agency
identified as legally deficient ``are so substantially inadequate that
the State cannot attain or maintain the NAAQS or otherwise comply with
the CAA.'' The commenter claimed that the EPA should have evaluated all
of the state's emission limitations, emission inventories and
attainment and maintenance demonstrations for the NAAQS, rather than
focusing on these individual SIP provisions. In order to demonstrate
substantial inadequacy under section 110(k)(5), the state claimed, the
EPA ``must point to facts'' that show ``the State cannot attain or
maintain the NAAQS or comply with the CAA'' if the provisions remain in
the SIP. Other states made comparable arguments with respect to the SIP
provisions at issue in their SIPs and claimed that the EPA is required
to establish how the provisions caused or contributed to a specific
violation of a NAAQS in those states.
    By contrast, many environmental group commenters and individual
commenters took the opposite position concerning what is necessary to
support a finding of substantial inadequacy under section 110(k)(5).
These commenters argued that that the EPA may issue a SIP call not only
where it determines that a SIP is substantially inadequate to attain or
maintain a NAAQS with a technical analysis but also where the Agency
determines that the SIP is substantially inadequate ``to comply with
any requirement of the Act.'' The commenters noted that the EPA
identified specific statutory provisions of the CAA with which the SIP
provisions at issue in this action do not comply. For example, these
commenters agreed with the EPA's view that SIP provisions with
automatic or discretionary exemptions for emissions during SSM events
do not meet the fundamental requirements that SIP emission limitations
must apply to limit emissions from sources on a continuous basis, in
accordance with sections 110(a)(2)(A), 110(a)(2)(C) and 302(k). In
addition to arguing that failure to meet legal requirements of the CAA
is a sufficient basis for a SIP call, some commenters provided
additional support to illustrate how SIP provisions with deficiencies
such as automatic or discretionary exemptions for emissions during SSM
events result in large amounts of excess emissions that would otherwise
be violations of the applicable emission limitations.
    Response: The EPA disagrees with the argument that it has no
authority to issue a SIP call under section 110(k)(5) unless the Agency
provides a factual or technical analysis to demonstrate that the SIP
provision at issue caused a specific environmental harm or undermined a
specific enforcement case. As explained in the February 2013 proposal,
in the SNPR and in this final action, the EPA interprets its authority
under section 110(k)(5) to authorize a SIP call for not only provisions
that are substantially inadequate for purposes of attainment or
maintenance of the NAAQS but also those provisions that are
substantially inadequate for purposes of ``any requirement'' of the
CAA.\308\ To be clear, the EPA can also issue a SIP call whenever it
determines that a SIP as a whole, or a specific SIP provision, is
deficient because the SIP did not prevent specific violations of a
NAAQS, at a specific monitor, on a specific date. However, that is not
the extent of the EPA's authority under section 110(k)(5).
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    \308\ See February 2013 proposal, 78 FR 12459 at 12483-89
(February 22, 2013); SNPR, 79 FR 55919 at 55935.
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    On its face, section 110(k)(5) does not impose any explicit
requirements with respect to what specific form of factual or
analytical basis is necessary for issuance of a SIP call. Because the
statute does not prescribe the basis on which the EPA is to make a
finding of substantial inadequacy, the Agency interprets section
110(k)(5) to provide discretion concerning what is necessary to support
such a finding. The Agency believes that the nature of the factual or
analytical basis necessary to make a finding is dependent upon the
specific nature of the substantial inadequacy in a given SIP provision.
    For example, when the EPA issued the NOX SIP Call to
multiple states because their SIPs failed to address interstate
transport adequately in accordance with section 110(a)(2)(D)(i)(I), the
Agency did base that SIP call on a detailed factual analysis including
ambient air impacts.\309\ In that situation, the specific requirement
of the CAA at issue was the statutory obligation of each state to have
a SIP that contains adequate provisions to prohibit emissions from
sources ``in amounts'' that ``contribute significantly to nonattainment
in, or interfere with maintenance by, any other State'' with respect to
the NAAQS. Because of the phrase ``in amounts,'' the EPA considered it
appropriate to evaluate whether each state's SIP was substantially
inadequate to comply with section 110(a)(2)(D)(i)(I) through a detailed
analysis of the emissions from the state and their impacts on other
states. Moreover, given the use of ambiguous terms in section
110(a)(2)(D)(i)(I) such as ``contribute significantly,'' the EPA
concluded that it was appropriate to conduct a detailed analysis to
quantify the amount of emissions that each of the affected states
needed to eliminate in order to comply with section 110(a)(2)(D)(i)(I)
for the specific NAAQS in question. However, the EPA's decision to
determine these facts and to conduct these analyses as a basis for that
particular SIP call action was due to the nature of the SIP deficiency
at issue and the wording of section 110(a)(2)(D)(i)(I). The EPA has
similarly issued other SIP calls for which the Agency determined that a
specific factual or technical analysis was appropriate to support the
finding of substantial inadequacy.\310\
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    \309\ See ``Finding of Significant Contribution and Rulemaking
for Certain States in the Ozone Transport Assessment Group Region
for Purposes of Reducing Regional Transport of Ozone,'' 63 FR 57356
(October 27, 1998).
    \310\ See, e.g., ``Finding of Substantial Inadequacy of
Implementation Plan; Call for Iowa State Implementation Plan
Revision,'' 76 FR 41424 (July 14, 2011) (SIP call to Iowa due to
PM2.5 NAAQS violations in Muscatine area); ``Approval and
Promulgation of State Implementation Plans; Call for Sulfur Dioxide
SIP Revisions for Billings/Laurel, MT [Montana],'' 58 FR 41430
(August 4, 1993) (SIP call to Montana due to modeled violations of
the SO2 NAAQS).
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    Not all situations, however, require the same type of detailed
factual analysis to support the finding of substantial inadequacy. For
example, when the EPA issued the PSD GHG SIP call to 13 states for
failure to have a PSD permitting program that properly addresses GHG
emissions, the Agency did not need to base that SIP call action on a
detailed factual analysis of ambient air impacts.\311\ In that
situation, the statutory requirement of the CAA in question was the
obligation of each state SIP under section 110(a)(2)(C) to

include a PSD permitting program that addresses all federally regulated
air pollutants, including GHGs. In that action, the EPA made a finding
that the SIPs of 13 states were substantially inadequate to ``comply
with any requirement'' of the CAA because the PSD permitting programs
in their EPA-approved SIPs did not apply to GHG emissions from new and
modified sources. Accordingly, the EPA issued a SIP call to the 13
states because their SIPs failed to comply with specific legal
requirements of the CAA. This failure to meet an explicit CAA legal
requirement to address GHG emissions in permits for sources as required
by statute did not require the EPA to provide a technical analysis of
the specific environmental impacts that this substantial inadequacy
would cause. For this type of SIP deficiency, it was sufficient for the
EPA to make a factual finding that the affected states had SIPs that
failed to meet this fundamental legal requirement.\312\ The EPA has
issued other SIP calls for which the Agency made a finding that a
state's failure to meet specific legal requirement of the CAA for SIPs
was a substantial inadequacy without the need to provide a technical
air quality analysis relating to NAAQS violations.\313\
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    \311\ See ``Action to Ensure Authority to Issue Permits Under
the Prevention of Significant Deterioration Program to Sources of
Greenhouse Gas Emissions; Finding of Substantial Inadequacy and SIP
Call,'' 75 FR 77698 (December 13, 2010). The EPA notes that a number
of petitioners challenged this SIP call on various grounds, but the
court ultimately determined that they did not have standing. Texas
v. EPA, 726 F.3d 180 (D.C. Cir. 2013).
    \312\ Id., 75 FR 77698 at 77705-07.
    \313\ See, e.g., ``Finding of Substantial Inadequacy of
Implementation Plan; Call for California State Implementation Plan
Revision,'' 68 FR 37746 (June 25, 2003) (SIP call to California for
failure to meet legal requirements of section 110(a)(2)(C), section
110(a)(2)(I), and section 110(a)(2)(E) because of exemptions for
agricultural sources from NNSR and PSD permitting requirements);
``Credible Evidence Revisions,'' 62 FR 8314 at 8327 (February 24,
1997) (discussing SIP calls requiring states to revise their SIPs to
meet CAA requirements with respect to the use of any credible
evidence in enforcement actions for SIP violations).
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    The EPA believes that the most relevant precedent for what is
necessary to support a finding of substantial inadequacy in this action
is the SIP call that the Agency previously issued to the state of Utah
for deficient SIP provisions related to the treatment of excess
emissions during SSM events.\314\ In that SIP call action, the EPA made
a finding that two specific provisions in the state's SIP were
substantially inadequate because they were inconsistent with legal
requirements of the CAA. For one of the provisions that included an
exemption for emissions during ``upsets'' (i.e., malfunctions), the EPA
explained:
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    \314\ See ``Finding of Substantial Inadequacy of Implementation
Plan; Call for Utah State Implementation Plan Revision; Proposed
rule,'' 76 FR 21639 (April 18, 2011).

Contrary to CAA section 302(k)'s definition of emission limitation,
the exemption [in the provision] renders emission limitations in the
Utah SIP less than continuous and, contrary to the requirements of
CAA sections 110(a)(2)(A) and (C), undermines the ability to ensure
compliance with SIP emissions limitations relied on to achieve the
NAAQS and other relevant CAA requirements at all times. Therefore,
the [provision] renders the Utah SIP substantially inadequate to
attain or maintain the NAAQS or to comply with other CAA
requirements such as CAA sections 110(a)(2)(A) and (C) and 302(k),
CAA provisions related to prevention of significant deterioration
(PSD) and nonattainment NSR permits (sections 165 and 173), and
provisions related to protection of visibility (section 169A).\315\
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    \315\ Id., 76 FR 21639 at 21641. The EPA also found the first
provision substantially inadequate because it operated to create an
additional exemption for emissions during malfunctions that modified
the existing emission limitations in some federal NSPS and NESHAP
that the state had incorporated by reference into its SIP. The EPA's
1999 SSM Guidance had indicated that state SIP provisions could not
validly alter NSPS or NESHAP.

    For a second provision, the EPA made a finding of substantial
inadequacy because the provision interfered with the enforcement
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structure of the CAA. The EPA explained:

This provision appears to give the executive secretary exclusive
authority to determine whether excess emissions constitute a
violation and thus to preclude independent enforcement action by EPA
and citizens when the executive secretary makes a non-violation
determination. This is inconsistent with the enforcement structure
under the CAA, which provides enforcement authority not only to the
States, but also to EPA and citizens. . . . Because it undermines
the envisioned enforcement structure, it also undermines the ability
of the State to attain and maintain the NAAQS and to comply with
other CAA requirements related to PSD, visibility, NSPS, and
NESHAPS.\316\
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    \316\ Id.

    In the Utah SIP call rulemaking, the EPA received similar adverse
comments arguing that the Agency has no authority under section
110(k)(5) to issue a SIP call without a factual analysis that proves
that the deficient SIP provisions caused a specific environmental harm,
such as a NAAQS violation. Commenters in that rulemaking likewise
argued that the EPA was required to prove a causal connection between
the excess emissions that occurred during a specific exempt malfunction
and a specific violation of the NAAQS. In response to those comments,
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the EPA explained:

    [W]e need not show a direct causal link between any specific
unavoidable breakdown excess emissions and violations of the NAAQS
to conclude that the SIP is substantially inadequate. It is our
interpretation that the fundamental integrity of the CAA's SIP
process and structure is undermined if emission limits relied on to
meet CAA requirements can be exceeded without potential recourse by
any entity granted enforcement authority by the CAA. We are not
restricted to issuing SIP calls only after a violation of the NAAQS
has occurred or only where a specific violation can be linked to a
specific excess emissions event.\317\
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    \317\ Id., 76 FR 21639 at 21643.

    The EPA's interpretation of section 110(k)(5) in the Utah action
was directly challenged in US Magnesium, LLC v. EPA.\318\ Among other
claims, the petitioners argued that the EPA did not have authority for
the SIP call because the Agency had not ``set out facts showing that
the [SIP provision] has prevented Utah from attaining or maintaining
the NAAQS or otherwise complying with the CAA.'' Thus, the same
arguments raised by commenters in this action have previously been
advanced and rejected by the EPA and the courts. The court expressly
upheld the EPA's interpretation of section 110(k)(5), concluding:
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    \318\ 690 F.3d 1157 (10th Cir. 2012).

    Certainly, a SIP could be deemed substantially inadequate
because air-quality records showed that actions permitted under the
SIP resulted in NAAQS violations, but the statute can likewise apply
to a situation like this, where the EPA determines that a SIP is no
longer consistent with the EPA's understanding of the CAA. In such a
case, the CAA permits the EPA to find that a SIP is substantially
inadequate to comply with the CAA, which would allow the EPA to
issue a SIP call under CAA section 110(k)(5).\319\
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    \319\ Id. 690 F.3d at 1168.

    Finally, the EPA disagrees with the commenters on this specific
point because it is not a logical construction of section 110(k)(5).
The implication of the commenters' argument is that if a given area is
in attainment, then the question of whether the SIP provisions meet
applicable legal requirements is irrelevant. If a given area is not in
attainment, then the implication of the commenter's argument is that
the EPA must prove that the legally deficient SIP provision factually
caused the violation of the NAAQS or else the legal deficiency is
irrelevant. In the latter case, the logical extension of the
commenter's argument is that no matter how deficient a SIP provision is
to meet applicable legal requirements, the EPA is foreclosed from
directing the state to correct that deficiency unless and until there
is proof of a specific environmental harm caused, or specific
enforcement case thwarted, by that deficiency. Such a reading is
inconsistent with both the letter and the intent of section 110(k)(5).