SIP revisions as part of the action issuing a new CTG. These proposed
approaches would apply to covered sources in nonattainment areas and
portions of a state located in an OTR subject to new RACT SIP
obligations.
    b. Final Rule. The EPA is finalizing a combination of the proposed
approaches, as codified at 40 CFR 51.1312(a)(2) and (3). For CTGs
issued between November 15, 1990, and the date of attainment, CAA
section 182(b)(2) requires a state to submit the associated RACT SIP
revision, where applicable, within the timeframe established by the
Administrator in issuing the CTG. The EPA interprets this provision as
authorizing the Administrator to set a SIP submission deadline in the
action issuing any future CTG. However, the agency is also establishing
a default submission deadline of no later than 24 months after the
effective date of the action issuing the CTG, which is grounded in our
overall approach for RACT SIP revisions outlined in CAA section 182(b),
in the event that the Administrator does not set an alternative
submission deadline as part of a CTG action.
    While CAA section 182(b)(2) addresses the submission requirements
for RACT SIP revisions triggered by new CTGs, the CAA is otherwise
silent regarding the schedule for implementation of those RACT SIP
revisions triggered by new CTGs. When new CTGs are issued, these RACT
SIP revisions would be applicable to areas classified Moderate or
higher, and to any portion of a state located in an OTR. For CTGs in
effect at the time of initial area designations for a revised NAAQS,
the EPA has interpreted the relevant CAA provisions to require
implementation of related RACT SIP revisions as expeditiously as
practicable, but no later than January 1 of the fifth year after the
effective date of initial designations for the revised NAAQS (80 FR
12279; March 6, 2015). For RACT SIP revisions triggered by new CTGs
issued after initial area designations, we are adopting the proposed
default implementation deadline of no later than January 1 of the third
year after the associated SIP revision submission deadline. We
anticipate that this adopted default implementation deadline will
provide an overall RACT schedule similar to that for sources subject to
CTG requirements upon initial area designations.
    We are also articulating in this final rule the Administrator's
authority to establish an alternative to the default deadline for
implementing RACT SIP revisions, as part of the action issuing a new
CTG. Under this option, setting a RACT SIP revision implementation
deadline as part of a CTG action would allow the Administrator to
tailor the implementation timeframe to the particular technical
considerations and attainment objectives associated with the sources
subject to the CTG and the overall attainment schedule. The adopted
approaches for establishing RACT SIP submission and implementation
deadlines would apply to covered sources in nonattainment areas and
portions of a state located in an OTR subject to new RACT SIP
obligations.
    c. Comments and Responses. Comment: Several commenters stated that
a default submission deadline is not necessary for RACT SIP revisions
triggered by the issuance of a CTG after initial area designations.
They noted that the CAA expressly authorizes the Administrator to set a
RACT SIP submission deadline as part of the related CTG document, and
that a default deadline is either redundant or

could be interpreted to restrict the Administrator's authority.
    Response: The EPA agrees with commenters that CAA section 182(b)(2)
authorizes the Administrator to set a RACT SIP submission deadline as
part of the related CTG document. As discussed previously, CAA section
182(b)(2) expressly requires that states submit RACT SIP revisions
triggered by new CTG issuance within a period established by the
Administrator, and we interpret this provision to authorize--but not
require--the Administrator to set a RACT SIP submission deadline in the
action issuing the CTG. As a result, we are adopting the proposed
default SIP submission deadline of no later than 24 months after the
effective date of the action issuing the CTG, in addition to affirming
in this final rule the Administrator's existing authority to set an
alternative RACT SIP submission deadline as part of the action issuing
the CTG.

C. Requirements for RACM: Consideration of Sources of Intrastate
Transport of Pollution

1. Summary of Proposal
    As discussed in Section III.F.2 of this preamble, the EPA proposed
to require that, for each nonattainment area for which an attainment
demonstration is required (see Section III.D of this preamble), an air
agency shall submit with the attainment demonstration a SIP revision
demonstrating that it has adopted all RACM necessary to demonstrate
attainment as expeditiously as practicable and to meet any RFP
requirements. The EPA further proposed to codify the existing
requirement under CAA section 172(c)(6) that, in addition to sources
located in an ozone nonattainment area, air agencies must also consider
the impacts of emissions from sources outside an ozone nonattainment
area (but within a state's boundaries), and must require other control
measures on these intrastate sources if doing so is necessary to
provide for attainment of the applicable ozone NAAQS within the area by
the applicable attainment date. This proposed rulemaking provision is
consistent with SIP elements required under the CAA, as well as
existing EPA interpretations of CAA section 172(c)(6) as articulated in
previous NAAQS implementation rulemakings.
2. Final Rule
    The EPA is finalizing the requirement regarding consideration of
``other control measures'' for intrastate sources of pollution, as
proposed. CAA section 172(c)(6) requires that SIP provisions include
enforceable emission limitations and other control measures, means or
techniques as may be necessary or appropriate to attain a standard by
the applicable attainment date. The EPA interprets this provision to
include ``additional reasonable measures,'' which are those measures
and technologies that can be applied to any emissions source within the
state's jurisdiction, including those outside of a nonattainment area.
Upwind sources within a state may have a significant impact on air
quality in a downwind nonattainment area, and failure to consider and
require, as appropriate, reasonable control measures for these sources
may preclude attainment of a NAAQS by the attainment date. Though not
directly a part of a nonattainment area RACM analysis, the EPA has
addressed this ``other control measures'' provision in the preamble
discussions for previous NAAQS implementation rulemakings,\34\ and for
clarity is codifying this interpretation in this final rule at 40 CFR
51.1312(c). As discussed in Section III.F of this preamble, the EPA is
otherwise adopting all RACM requirements for purposes of the 2015 ozone
NAAQS, based on the rationale and approach articulated in the final
2008 Ozone NAAQS SIP Requirements Rule.
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    \34\ See the Phase 2 proposed rulemaking (68 FR 32829; June 2,
2003) and final rule to implement the 8-hour ozone NAAQS (70 FR
71623; November 29, 2005), and the final rule to implement the
PM2.5 NAAQS (81 FR 58035; August 24, 2016).
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3. Comments and Responses
    Comment: A number of commenters opposed the EPA's interpretation of
CAA section 172(c)(6) as applying to emissions sources outside of
designated nonattainment areas. As one commenter stated, the plain
language of CAA section 172 in general focuses its discussions and
references to sources within a designated nonattainment area, and makes
no mention of requiring emission reductions for sources outside the
nonattainment area.
    Response: The EPA disagrees with the commenters concerning the
proper application of CAA section 172(c)(6). Unlike other SIP
requirements under CAA section 172(c)(1), such as RACM/RACT-level
controls on sources located in a nonattainment area, CAA section
172(c)(6) is not limited by its terms to sources located in the
nonattainment area. Upwind sources within a state may have a
significant impact on air quality in a nonattainment area, and CAA
section 172(c)(6) imposes a potential obligation upon states to impose
emission controls on sources located outside a designated nonattainment
area that are in addition to, and beyond those, otherwise required on
sources located the nonattainment area, if necessary or appropriate for
purposes of attainment by the attainment date.
    Comment: Some commenters contended that emissions from sources
outside a nonattainment area, if nearby and affecting a nonattainment
area's ability to timely attain, should be accounted for in setting
nonattainment area boundaries as part of the designations process under
CAA section 107(d).
    Response: The EPA agrees with commenters that a designated
nonattainment area should already include the nearby sources that, at
the time of designations, were determined to be contributing to
violations in the area. But we disagree that the designations process
under CAA section 107(d) is the exclusive approach for identifying
relevant contributing sources for a nonattainment area, as there may be
additional contributing sources within a state that were not
sufficiently ``nearby'' the area, or were otherwise not identified in
the nonattainment area designations process as contributing to
violations in the area. Consistent with our existing policy, the EPA
interprets CAA section 172(c)(6) as imposing a separate obligation to
consider and control sources located outside of a nonattainment area
but within a state's jurisdiction, if necessary or appropriate to
attain a standard by the applicable attainment date.
    Comment: Multiple commenters interpreted the EPA's proposal as
imposing a mandatory requirement for states to consider and implement
emission controls for intrastate sources located outside of a
designated nonattainment area. Some commenters characterized the
proposal as requiring RACM outside a nonattainment area, where other
commenters requested that we further clarify a state's discretion,
under CAA section 172(c)(6), to consider and require ``other control
measures'' for sources located outside of a nonattainment area.
    Response: The EPA believes our interpretation of CAA section
172(c)(6), under certain circumstances, establishes a mandatory
requirement for states to consider and implement emission controls for
sources inside the state but outside of a designated nonattainment
area. The language of the statute, and our adopted regulatory text in
40 CFR 51.1312(c), describe a conditional requirement for placing
controls such sources, i.e., states are required to impose controls on
sources located outside of a nonattainment area but

within the state's jurisdiction, only in circumstances where that is
necessary or appropriate to provide for attainment by the attainment
date, because the emission controls required on sources within the
nonattainment area are not sufficient to provide for attainment by that
date. This qualification indicates that the obligation is tied to the
attainment needs of the nonattainment area in question and does not
apply more broadly. Further, the EPA emphasizes that we do not
interpret section 172(c)(6) to automatically require states to conduct
an evaluation of all sources and all potential controls throughout the
entire state regardless of attainment needs. However, if necessary to
achieve attainment by the applicable attainment date, the EPA believes
the CAA obligates states to place emission controls on significant
emissions sources elsewhere within the state as needed to achieve the
necessary reductions.

D. Nonattainment NSR Offset Requirement: Interprecursor Trading for
Ozone Offsets

1. Summary of Proposal
    In response to a petition for reconsideration granted on November
5, 2015, the EPA proposed to reaffirm our longstanding policy regarding
IPT for ozone, which is currently codified at 40 CFR 51.165(a)(11) and
part 51 Appendix S, section IV.G.5,\35\ by re-proposing the existing
regulatory provisions with revised text, and adding specific criteria
for developing and implementing an IPT program.\36\ In addition, the
EPA indicated that the re-proposed IPT provision, when finalized, would
supersede any previous ozone IPT policy articulated in earlier EPA
guidance.\37\ Further, the November 17, 2016, proposal explained that
the EPA proposed no other changes to the existing requirements in the
NNSR regulations.\38\
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    \35\ The EPA originally added these provisions specific to ozone
to the NNSR regulation in 2015 as part of the final 2008 Ozone NAAQS
SIP Requirements Rule. See 80 FR 12264 at 12288.
    \36\ See 81 FR at 81295-8.
    \37\ The EPA's prior guidance concerning the use of IPT to
satisfy the NNSR requirements for emissions offsets was contained in
a 2001 EPA document titled ``Improving Air Quality with Economic
Incentive Programs'' (January 2001). The EPA's policy on IPT for
ozone, as finalized through this rulemaking, supersedes the
information contained in that earlier document specifically with
respect to IPT.
    \38\ In the proposal, the EPA did not propose to change or seek
comment on any existing NNSR emissions offsets requirements
contained in the NNSR regulations at 40 CFR 51.165 and part 51
Appendix S. Existing NNSR emissions offset requirements are based
largely on part D of title I of the CAA's nonattainment
requirements. These existing requirements include the statutory
offset ratios applicable in specific ozone nonattainment areas
(based on an area's classification for ozone), geographic
restrictions as to where creditable emissions reductions may be
obtained and other criteria concerning the creditability of
emissions reductions to be used as offsets.
---------------------------------------------------------------------------

    The proposal noted the EPA's continued interpretation that the CAA
accommodates the use of technically supported IPT to satisfy the NNSR
offset requirement. As discussed in greater detail in the Comments and
Responses section that follows, the EPA stated at proposal that the CAA
allows the total annual tonnage of emissions of one ozone precursor to
be offset by reductions in total actual annual emissions of another
ozone precursor (in units of tons per year (tpy)) pursuant to an IPT
ratio that shows the reductions will have an equivalent or greater air
quality benefit. The proposal explained that the authority to permit
IPT is based on the language of section 173(c)(1) of the CAA and the
definition of ``air pollutant'' in section 302(g) of the CAA, and that
ozone is the regulated pollutant at issue (rather than NOX
or VOC, which are both recognized precursors to the formation of
ground-level ozone concentrations).
    The EPA proposed that states interested in implementing an ozone
IPT program must submit the following to the EPA as part of a plan for
approval: (1) IPT provision(s), including area-specific default IPT
ratio(s),39 40 where applicable; (2) a description of the
air quality model(s) used to develop any default IPT ratio(s); and (3)
an accompanying modeling demonstration showing that such ratio(s)
provide an equivalent or greater air quality benefit with respect to
ground level ozone concentrations in the ozone nonattainment area than
an offset of the emitted precursor would achieve.
---------------------------------------------------------------------------

    \39\ An IPT ratio sets the appropriate proportion for the
amounts of each precursor in tpy of emissions, which is intended to
ensure that the substitution of one ozone precursor for another in
an offset transaction provides an equivalent or greater air quality
benefit with respect to ground level ozone concentrations in the
ozone nonattainment area. The IPT ratio is separate and distinct
from the statutory offset ratios contained in the CAA that are
directly associated with area classifications for ozone
nonattainment areas. See e.g., CAA Section 182(b)(5) (establishing
an offset ratio of 1.15 to 1 for Moderate areas). Both ratios must
be applied in determining the appropriate emissions offset that must
be applied for a particular offset transaction if one ozone
precursor is being used to offset a different ozone precursor. An
example of a simple offset calculation with the application of an
IPT ratio would be a major NNSR proposed source in a Moderate area
seeking to offset a 200 tpy NOX increase with reductions
in VOC from another source or the respective SIP approved Emission
Reduction Credit Bank. First, the 200 tpy NOX offset is
subject to the 1.15 Moderate area offset ratio, then the product is
multiplied by the IPT ratio (either area-wide or case-specific
derived from technical demonstration). If we assume the IPT ratio in
this case is 5, the resulting equation is: (200 tpy NOX)
x (1.15(Moderate area offset ratio)) x (5 VOC/
NOX (IPT ratio applied)) = 1,150 tpy total NOX
(offset) required for NNSR permitting purposes.
    \40\ Hereafter referred to as default IPT ratio(s) or default
ratio(s).
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    The EPA recommended that each air agency implementing an IPT
program consult with the appropriate EPA Regional office as the air
agency develops a modeling protocol to establish a default IPT ratio or
ratios \41\ for a nonattainment area. The EPA sought comments on the
proposed contents of the plan submission and the approach for
establishing any default IPT ratios.
---------------------------------------------------------------------------

    \41\ The draft Technical Guidance Document provided in the
docket supports the division of a nonattainment area into sub-areas
with a technical demonstration substantiating the need for separate
ratios in specific portions of a nonattainment area.
---------------------------------------------------------------------------

    When the EPA published our NNSR implementation rules for
PM2.5 in 2008, we indicated that, while the new
implementation rules allowed air agencies to adopt IPT programs to
satisfy the NNSR offset requirements for PM2.5, such IPT was
not permissible for netting purposes. See 73 FR 28340 (May 16, 2008).
Consistent with that policy, in the proposal the EPA proposed that an
IPT program could not be used for purposes of netting under the NNSR
program.
    The EPA also indicated in the proposal that we have interpreted the
CAA to preclude the use of ozone IPT where an air agency chooses to
include emissions reductions attributable to the NNSR air permitting in
its initial 15 percent ROP plan for those Moderate or higher ozone
nonattainment areas that are satisfying this ROP requirement for the
first time under CAA section 182(b)(1)(A)(i). This interpretation
results from the fact that the CAA requires that a state's initial ROP
plan can be satisfied only via reductions in VOC emissions. Hence, the
EPA proposed that such a plan could not count emission reductions
attributable to a NNSR permitting program utilizing IPT flexibilities,
for ROP purposes.\42\
---------------------------------------------------------------------------

    \42\ See section III.E of this preamble.
---------------------------------------------------------------------------

    Finally, the EPA in the November 17, 2016, proposal also explained
that IPT could be implemented in several ways; the primary variable
being the method in which the IPT ratio for ozone precursors is
established by an air agency or permit applicant and applied in a
particular ozone nonattainment area. That is, the EPA proposed that
states be allowed to choose any of the options presented in the
proposal. Accordingly, with the goal of providing flexibility to air
agencies and sources, the EPA proposed and sought comment

on the following implementation options:
    a. Case-specific Permit Ozone IPT Ratios. Under a case-specific IPT
ratio option, state plans would generally require each permit applicant
who chooses to use ozone IPT as the means for satisfying the NNSR
emissions offset requirement to calculate and submit to the reviewing
authority the appropriate IPT ratio. In choosing this option, the state
would be required to include for the EPA's approval a plan submission
addressing NNSR program provisions that explicitly authorize case-
specific IPT ratios for the particular ozone nonattainment area(s).
Also, such a plan submission must include the procedures by which
permit applicants may use IPT, including a description of the model(s)
that will be used, the calculation of the IPT ratio, and a
demonstration that such IPT ratio provides an equivalent or greater air
quality benefit for ozone concentrations in the ozone nonattainment
area. The EPA also proposed that the state's IPT provision must provide
that any IPT ratio that an applicant proposes for an individual permit
must be approved by both the reviewing authority and the EPA.
    b. Area-specific Default Ozone IPT Ratio. Under the proposed area-
specific default IPT option, the EPA proposed that a state plan could
include a default IPT ratio that may be used by permit applicants to
obtain IPT offsets for all applicable NNSR permits issued in a
particular ozone nonattainment area. Under this proposed option, the
state's plan submission would be required to provide a description of
the model(s) used, the calculated ratio and the technical demonstration
substantiating the equivalent or greater ozone benefit in that
nonattainment area. The EPA further proposed that a ratio that has
become part of an approved plan and has undergone public comment during
the plan approval process would not require further EPA approval or be
subject to additional public comment each time that ratio is utilized
by individual permit applicants.
    c. Combination of an Area-specific Default Ozone IPT Ratio and
Case-specific IPT Ratios. As explained in the proposed rulemaking, the
EPA believes that it is reasonable for air agencies to have the option
of implementing as part of their NNSR programs either a case-specific
IPT ratio or a default IPT ratio. The EPA also believes that air
agencies with EPA-approved NNSR programs should have the option of
implementing a combination of the two proposed options. Such a combined
program would enable an air agency to develop a default IPT ratio,
while at the same time allowing an individual permit applicant to
propose an alternative case-specific IPT ratio (if it can demonstrate
to the satisfaction of both the reviewing authority and the EPA that
such alternative ratio is appropriate for the proposed offsetting
transaction for a specific permit application).
    d. Limitations for Implementing Ozone IPT under Appendix S. In the
specific case where a state lacks an approved NNSR program and issues
NNSR permits under the requirements contained in the EPA's Emission
Offset Interpretative Ruling at 40 CFR part 51, Appendix S (Appendix
S), the EPA proposed that states would be limited to the use of case-
specific IPT ratios.
    In addition to the four options proposed for implementing the IPT
program for ozone, the EPA proposed to require air agencies to review
any default IPT ratio(s) that is included in their EPA-approved IPT
program at least every 3 years (from the air agency's prior plan
submission containing any such area-specific default IPT ratio(s)) to
ensure that the ratio continues to be valid for IPT offsets in the
area. To meet this proposed requirement an air agency would need to
submit new modeling to confirm that the ratio still defines an
equivalent or greater air quality benefit relationship between VOC and
NOX emissions regarding ozone formation in the particular
ozone nonattainment area.
    At proposal, the EPA included a draft TGD in the docket. The
purpose of this TGD was to provide air agencies with guidance on a
technical approach to determine ozone impacts from precursor emissions
for a specific nonattainment area or for case-by-case determinations.
2. Final Rule and Rationale
    In this final rule, the EPA is promulgating a discretionary IPT
program for ozone with changes from the proposed rulemaking based on
comments received. The final rule allows states to implement their IPT
program using any of the proposed implementation options as follows:
(1) Default IPT ratios, (2) case-specific IPT ratios or (3) a
combination of the two options, whereby a proposed source may, at the
approval of the reviewing authority, propose a case-specific ratio in
lieu of an available default IPT ratio. The following changes are being
made in response to comments received: (1) Air agencies will not be
required to obtain EPA approval of IPT ratios when implementing a case-
specific IPT program or when applying default IPT ratios that are not
included in the state regulations and the SIP; and (2) the required
periodic review of any default IPT ratio must be conducted every 5
years, rather than every 3 years as proposed.
    The EPA acknowledges, based on comments received, that the
requirement of EPA approval of IPT ratios could impose additional
burdens and result in permit delays. Hence, in the final rule, the EPA
is eliminating this approval requirement for the case-specific ratios
and for default ratios that are not included in state regulations and
the SIP. In the spirit of cooperative federalism, the EPA encourages
air agencies to both work with the EPA in the development of IPT ratios
and notify the EPA after the development of any initial or revised
area-specific default IPT ratio for a particular ozone nonattainment
area. Finally, the EPA will, of course, also have an opportunity to
review and comment on the application of any IPT ratio (default or
case-specific) to a particular source or location during the public
comment period afforded as part of the NNSR permitting process.
    An air agency may choose to include a numerical default ratio in
its NNSR regulations and the SIP to make that ratio controlling.
Alternatively, if an air agency chooses not to include any numerical
default IPT ratios in its regulations and SIP, EPA approval of the
numerical default ratio is no longer required. However, for any such
air agency, the final rule still requires the SIP to include (1) the
authority to implement IPT; (2) a description of the air quality
model(s) that may be used to develop any default IPT ratio; and (3) a
description of the approach that the air agency will use to develop any
default IPT ratio, which must show that such ratios provide an
equivalent or greater ozone air quality benefit in the applicable ozone
nonattainment area. The final rule also requires air agencies with IPT
programs that authorize case-specific IPT ratios to require permit
applicants to include along with the submittal of the proposed case-
specific ratio similar information pertaining to the development of the
ratio.
    A default IPT ratio that is not in a state regulation and an
approved SIP would be subject to public comment for each use in
individual permits. Therefore, states may want to include numerical
default IPT ratios in their regulations and submit them to the EPA for
approval as part of the SIP. In such an instance, the regulation
containing the area-specific default IPT ratio would be reviewed by the
EPA as part of the SIP submission and, if approved, would provide
states and other stakeholders with greater certainty that the IPT ratio
will be applicable to all permit

applications. The validity of a default IPT ratio that has become part
of an approved plan and has undergone public comment during the plan
approval process would not be subject to additional public comment with
regard to its numerical value each time that ratio is utilized by
individual permit applicants.
    On the other hand, default ratios that are not included in a state
regulation and SIP, and, therefore, are not subject to the EPA's
approval, may be replaced more rapidly in situations where the ratio is
no longer valid, e.g., as a result of a periodic review. An air agency
can replace such a ratio with a revised value that will not have to be
processed through rulemaking and a plan revision. Also, if an air
agency determines through a periodic review that an existing default
ratio is no longer valid and must be revised, the air agency may decide
not to revise it but to rely solely on case-specific permit ratios to
continue implementing IPT provided that the SIP contains the necessary
authority to implement case-specific ratios as part of the NNSR program
for ozone. Unlike the default IPT ratios, case-specific IPT ratios will
not require periodic review because the ratio used for each individual
permit will be based on the most current data representing the ozone
chemistry for the area of concern.
    This final rule does not discourage or preclude an air agency
desiring EPA approval from electing to either submit numerical default
IPT ratio(s) to EPA for review and approval into its SIP, seek EPA
approval of any case-specific IPT ratio or to simply seek consultation
with the EPA on the development of any IPT ratio for ozone.
    For any state that lacks an approved NNSR program for ozone, the
state may issue an NNSR permit pursuant to the NNSR requirements for
ozone contained in 40 CFR part 51 Appendix S, which includes an IPT
program. The final rule provides that the IPT program under Appendix S
may be implemented only by using case-specific IPT ratios. In addition,
the final rule includes a provision in Appendix S that requires permit
applicants to include along with the submittal of the proposed case-
specific ratio information pertaining to the development of that ratio.
Moreover, each case-specific permit IPT ratio would not require EPA
approval but only the approval of the air agency.
    The EPA is including a revised final TGD in the docket for this
rulemaking. The purpose of this TGD is to provide air agencies and
source owners or operators, where applicable, with guidance on a
technical approach to determine ozone impacts from precursor emissions
for a specific nonattainment area or for case-specific determinations.
The TGD provides a framework and associated general methodology to
apply existing or new empirical relationships between ground level
ozone concentrations and the two precursors--NOX emissions
and VOC emissions--to develop the required IPT ratios.\43\ Air agencies
may use existing modeling analyses or generate their own modeling
analyses to provide the basis for the development of IPT ratios.\44\
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    \43\ Please refer to the TGD included in this final rule docket
and the section of the Response to Comments document related to the
proposed TGD for further information.
    \44\ The EPA has not added any regulatory provisions in the NNSR
regulations to require permitting authorities to use the data or
methods described in the TGD.
---------------------------------------------------------------------------

    In addition, recent changes to the EPA's Guideline for Air Quality
Models, published as Appendix W to 40 CFR part 51, provides greater
clarity regarding the use of chemical transport modeling to estimate
single-source ozone impacts from precursors. Appendix W provides
guidelines for area-specific assessments of precursor emissions impacts
on ozone and these guidelines may also support the development of case-
specific IPT ratios or area-specific IPT ratios for ozone precursors.
    Finally, the final rule attempts to strike a balance between
providing flexibility for the offset requirement in NNSR permitting and
compliance with the CAA's air quality protections. While EPA approval
of ratios is no longer required, the EPA believes that the SIP
requirements for air agencies to comply with the criteria for
development of default IPT ratios and to conduct periodic reviews of
each default ratio, along with the opportunity for the EPA to review
the application of a ratio for a specific permit during the public
comment period, afford adequate safeguards. In particular, the
mandatory periodic review conducted by the air agency will ensure that
each area-specific ratio either continues to adequately reflect the
correct relationship between VOC and NOX emissions with
respect to the formation of ground level ozone in a particular ozone
nonattainment area or will result in such ratio being eliminated (and
revised if so desired).
3. Comments and Responses
    Comment: Six commenters expressed concerns about the administrative
burden associated with the proposed requirement for the EPA to approve
all IPT ratios for ozone. These commenters believed that the EPA's
approval of the SIP containing the authority to use IPT and the
methodology for developing an IPT ratio would be sufficient. The
commenters claimed that the EPA's approval of SIPs containing rules
authorizing IPT is sufficient for compliance with the CAA requirements
for EPA approval of SIPs, while the specific ratios applied to IPT
should be a matter of NNSR permitting. The commenters stated that the
CAA assigns the EPA a substantive role in approving SIPs but generally
reserves NNSR permitting decisions to states. They thereby concluded
that the determination of specific IPT ratios should be considered the
province of the air agency and should not require EPA approval. One
commenter, while generally opposing the proposed IPT provisions, argued
that EPA approval of ratios would provide minimal, if any, benefit and
that the EPA lacked the resources sufficient for such a process to be
successful.
    Response: The EPA has considered the commenters' concerns about the
proposed requirement for EPA approval of all IPT ratios for ozone. As a
result, we have concluded that it would be appropriate to eliminate the
proposed EPA approval requirement as part of the final rule while
retaining the following safeguards: The final rule requires the SIP to
include (1) the authority to implement IPT; (2) a description of the
air quality model(s) that may be used to develop any default ratio; and
(3) a description of the approach that the air agency will use to
develop any default IPT ratio, which will show that such ratio(s)
provide an equivalent or greater ozone air quality benefit in the
applicable ozone nonattainment area. Accordingly, the final rule does
not require EPA approval of any IPT ratio. The EPA agrees that the
process of EPA approval could lengthen the time required for SIP
approval (in the case of default IPT ratios) and for individual permit
processing (in the case of case-specific IPT ratios).
    However, the EPA also believes that SIP approved default IPT ratios
have great potential in burden reduction for both proposed projects as
well as the state through an initial up-front effort in providing the
technical demonstration supporting the desired default ratio with an
equivalent or greater air quality benefit for such ratio's use in NNSR
permitting. A SIP approved default IPT ratio could be used to provide a
greater degree of certainty for projects each time it is used in an
NNSR permit, since it would be presumed to be appropriate for each
individual NNSR permit in that nonattainment area. To avail this
greater

certainty of default IPT ratios, an air agency could choose to obtain
formal approval of any default ratio by including it in its SIP
submission.
    The EPA recommends that air agencies consult with the EPA and refer
to the TGD for assistance in developing the technical demonstration
supporting IPT as providing an equivalent or greater air quality
benefit in the nonattainment area, whether implementing a case-specific
or area-specific default ratio. The EPA also offers direct assistance
to air agencies in the development of default IPT ratios upon request.
    Comment: Seven commenters advocated that the EPA take greater
responsibility for the development of default IPT ratios. Five of the
seven specifically recommended that the EPA provide the area-specific
IPT ratios for ozone nonattainment areas to the air agencies. Two of
the commenters, supporting a greater EPA responsibility, called upon
the EPA to provide assistance to the states in developing default IPT
ratios. All seven commenters generally agreed that the process to
develop default IPT ratios is too burdensome for the states to conduct
on their own. A state air agency commenter recommended that the EPA
provide a mechanism to establish an alternative ratio ``that does not
rely upon overly burdensome modeling exercises.'' The same commenter
suggested that the EPA could instead rely upon a ratio of
NOX and VOC inventories rather than photochemical modeling.
    Response: While the EPA continues to support the concept of a
default ratio for a particular ozone nonattainment area, primarily for
resource reasons it is not feasible at this time for the EPA to assume
the responsibility for establishing ratios for all ozone nonattainment
areas across the country. Additionally, it is not clear whether all
states will adopt the discretionary IPT provisions or whether they will
prefer default or case-specific IPT ratios. Taking into account these
considerations, and the considerable resources required to conduct
research and data analyses to establish IPT ratios for every
nonattainment area, the EPA believes that it is more appropriate for
states to assume the responsibility for developing IPT ratios for
nonattainment areas if they decide to implement the voluntary IPT
program.
    Concerning the commenters' recommendation for a mechanism for an
alternative ratio that can be derived without reliance on a modeling
demonstration, the EPA is not aware of an alternate methodology to show
equivalent or greater ozone air quality benefit in a nonattainment
area, which is an essential component of an acceptable ozone IPT ratio,
nor has the commenter provided such methodology for consideration.
Moreover, a ratio that relied upon NOX and VOC emissions
inventories, as recommended by one commenter, would not be based on an
air quality relationship between the two ozone precursors and would
lack elements of the required technical demonstration to substantiate
the required equivalent or greater air quality benefit for the ozone
nonattainment area than a reduction (offset) of the emitted precursor
would achieve.
    Comment: One commenter recommended the EPA not allow case-specific
IPT ratios because such ratios could not be set in advance of the
permitting process, although permit applicants need to know the
appropriate amount of the precursor offsets that would be required in
order to decide whether to apply for an NNSR permit.
    Response: Any major NNSR permit applicant would be required to do
preliminary analysis to determine the Lowest Achievable Emissions Rate
(LAER) and the amount of emissions offsets required. The EPA recognizes
the importance of an applicant of knowing, in advance of applying for a
permit to construct, the amount of emissions reductions that will be
needed to satisfy the NNSR offset requirement. If a state has chosen to
provide a default ratio, then that information is readily available to
the applicant when contemplating a proposed construction project. If,
however, a state also allows case-specific IPT ratios and the applicant
believes that a lower, less conservative ratio may be more appropriate
for the proposed project at a particular location within a
nonattainment area, then the applicant may elect to propose in advance
of the submittal of a permit application a case-specific IPT ratio that
would apply only to that source project. Thus, the case-specific IPT
ratio remains a valid option for permit applicants that find it useful.
    Comment: Some commenters expressed concern that the final rule
would only allow one approach for developing the required IPT ratio.
One commenter was concerned that states with more than one ozone
nonattainment area would be required to select one approach to apply to
all nonattainment areas within the state.
    Response: These commenters appear to have misunderstood the EPA's
proposal concerning the different options described for states to
consider in developing or revising IPT ratios for NNSR permitting. The
EPA did not intend to limit the flexibility afforded to states with
respect to how they can implement ozone IPT provisions (which includes
the approach indicated by these commenters). As previously explained,
the EPA proposed three options for states that choose for implementing
an IPT program for ozone: (1) Procedures to develop an area-wide IPT
ratio; (2) procedures to allow case-specific ozone IPT ratios
applicable to single permits; or (3) a combination of the first two
options with an area-specific default ratio that can be replaced by a
case-specific ratio as proposed by the applicant. The EPA's intent is
to maximize flexibility so that air agencies can choose a different
option for each nonattainment area, rather than choose one option to
apply at the statewide level, which means that two nonattainment areas
in the same state could apply different options for ozone IPT ratios.
The IPT program for ozone is not a mandatory program for air agencies
to adopt. However, air agencies that choose to use any form of IPT
program for ozone using the options provided in the final rule will
need to revise their SIPs to ensure that their NNSR rules satisfy the
minimum requirements contained in the final rule.
    Comment: Twelve commenters opposed the proposed requirement for a
3-year periodic review of any area-wide IPT ratios. Several of these
commenters opposed any review at all unless there is a specific basis
(e.g., a new or revised attainment demonstration) to justify the need
for review. Most of the remaining commenters recommended that a longer
review period (generally 5-10 years) would be more appropriate than the
proposed 3-year frequency. The commenters generally indicated that the
proposed 3-year review would be overly burdensome and likely not
reflect appreciable inventory changes. The commenters further noted
that updating an ozone IPT ratio every 3 years after initial SIP
approval requires months of modeling along with many weeks to follow
public notice requirements and other applicable state requirements.
    Response: The EPA considered the comments concerning the proposed
periodic review and the 3-year review cycle and has concluded that it
is appropriate to make certain changes to the proposed approach.
Specifically, the requirement for a periodic review of any default
ratio is being retained; however, such reviews will be required every 5
years rather than the proposed 3 years. The EPA notes that the
requirement for periodic review does not apply to case-specific IPT
ratios established for individual permits since each such ratio will be
based on the relevant technical

information applicable to that particular permitting situation. The EPA
disagrees with those commenters recommending that IPT review only occur
at the states' discretion. The EPA is establishing a periodic review
requirement for area-wide IPT ratios based on a 5-year review cycle to
address the potential for changes in atmospheric conditions in an area,
and to ensure that the requirement for equivalent or greater ozone
benefits continues to be satisfied.
    The increase in the length of the review was supported by
commenters in response to the proposal. Commenters supporting a review
period specifically noted that the 3-year period was too short. Many of
the commenters noted the procedural challenges in their own rulemaking
process and that other contributing elements to the nonattainment area
air shed do not change significantly enough to justify the effort of
the review.\45\ They concluded that a 3-year review cycle would be too
burdensome to adopt as a provision. Further, recent research suggests
ozone formation in an area changes over time but is typically fairly
consistent in a given 3 to 5-year period.\46\ Therefore, the EPA has
decided to increase the proposed 3-year review period to a 5-year
review period in order to provide air agencies a more reasonable period
of time to satisfy the requirement and to afford sufficient time to
reflect inventory changes. It is important to note that the final rule
would also not require EPA approval of periodically reviewed ratios
that are not included in regulations and the SIP. This will enable an
air agency to effectuate an updated default ratio more quickly, but
such a default ratio will be subject to public comment as part of the
NNSR permitting process. However, similar to the development of the
initial default ratio, the EPA encourages air agencies to both work
with the EPA in the development of a revised default IPT ratio for a
particular ozone nonattainment area and notify the EPA after such a
ratio has been developed.
---------------------------------------------------------------------------

    \45\ See Section VIII.B of the Response to Comments document for
further information.
    \46\ Evaluating a Space-Based Indicator of Surface Ozone-
NOx-VOC Sensitivity Over Midlatitude Source Regions and
Application to Decadal Trends, Xiaomeng Jin, Arlene M. Fiore, Lee T.
Murray, Lukas C. Valin, Lok N. Lamsal, Bryan Duncan, K. Folkert
Boersma, Isabelle De Smedt, Gonzalo Gonzalez Abad, Kelly Chance, and
Gail S. Tonnesen, Journal of Geophysical Research: Atmospheres,
October 5, 2017.
---------------------------------------------------------------------------

    Comment: Five commenters advocated that the EPA provide a
reasonable transition period for any pre-existing IPT programs that a
state may be currently implementing. Some of these commenters
explicitly recommended that states be allowed to continue the
implementation of pre-existing ozone IPT programs without including
revised IPT provisions as part of any other required revisions to the
ozone NNSR regulations.
    Response: Existing provisions in an EPA-approved SIP remain in
effect until any revisions to those provisions are approved by the EPA
as a revision to the SIP. Accordingly, states that already implement a
SIP-approved ozone IPT program can continue to implement that approved
program until the program is revised. States are required to submit a
SIP revision regarding the state's NNSR program. Even if a state
believes that its pre-existing IPT program is sufficient to meet the
requirements established in this rulemaking, the state's SIP submittal
must demonstrate this to be so by including information to support the
implementation of IPT subject to the requirements of this rule. In the
case of any default ratios that are already in a SIP, this includes a
technical demonstration supporting an equivalent or greater ozone air
quality benefit for the existing default IPT ratio, and a 5-year
periodic review.
    Comment: Two commenters objected to the proposed ozone IPT
provisions on the grounds that allowing IPT is unlawful. One of the
commenters claims the IPT provision would put human health at risk
because it contributes to delays in attaining the standards. The other
commenter provides a detailed argument claiming that the proposed ozone
IPT provision violates the express terms of the CAA. This commenter
interprets the offset requirement under CAA Section 173(c)(1), which
specifically refers to an ``air pollutant,'' to apply only to the
particular precursor emitted (VOC or NOx), rather than to
the ambient air pollutant (ozone) for which the region is in
nonattainment, noting that the Act establishes VOC-specific offset
ratios required for ozone permitting.
    Response: The EPA disagrees with the commenters' narrow
interpretation of ``air pollutant'' under CAA Section 173(c)(1).\47\
CAA section 302(g), which defines ``air pollutant,'' provides that the
term includes ``. . . any precursors to the formation of any air
pollutant, to the extent the Administrator has identified such
precursor or precursors for the particular purpose for which the term
`air pollutant' is used.'' (Emphasis added).\48\ Further, CAA section
109(a) directs the Administrator to promulgate NAAQS for ``each air
pollutant for which air quality criteria have been issued. . . .'' The
criteria pollutant in this context is ozone--not its precursors.
Further, in accordance with CAA section 107(d)(4), the air pollutant
for which the area is designated nonattainment is ozone, and there is
no mention of NOX or VOC.
---------------------------------------------------------------------------

    \47\ Section 173(c)(1) of the CAA states that the NNSR offset
requirement shall ``assure that the total tonnage of increased
emissions of the air pollutant from the new or modified source shall
be offset by an equal or greater reduction, as applicable, in the
actual emissions of such air pollutant from the same or other
sources in the area.'' (Emphases added.)
    \48\ See 57 FR 55620, November 25, 1992, at page 55621 and 55624
(PSD and NNSR Applicability), and 1991 Memo ``New Source Review
Program Transitional Guidance'' at page 5.
---------------------------------------------------------------------------

    While an area's attainment designation is made for the criteria air
pollutant ozone, the control of ground level concentrations of ozone
has occurred largely through regulation of its precursor emissions,
which are NOX and VOC. Both the CAA and the EPA's NNSR
regulations identify emissions of NOX and VOC as precursors
for ozone, and, as such, NOX and VOC are both regulated
under NNSR as part of the regulation of ozone (see 40 CFR
51.165(a)(xxxvii)(C)(1)). Thus, when applied to ozone, the term ``air
pollutant'' in section 173 of the Act may be read to describe both
NOX emissions and VOC emissions. The EPA, therefore, reads
the Act to allow the total annual tonnage of emissions of one ozone
precursor to be offset by reductions in total annual emissions of
another ozone precursor (in tpy) pursuant to an IPT ratio that
demonstrates that the reductions will have an equivalent or greater air
quality benefit with respect to ground level concentrations of the
ambient air pollutant ozone. Further, section 173(a)(1)(A) of the CAA
requires an NNSR permitting offset to be consistent with RFP (as
defined in CAA section 171(1)). Specifically, this provision requires
that the offsetting emissions reductions are such that the total
allowable emissions in the area, including the proposed source or
modification when the source commences operation, will be sufficiently
less than the emissions from the total emissions of existing sources
before the permit application, to represent RFP when considered
together with the provisions of the nonattainment SIP. Section 171(1)
of the CAA defines RFP as ``annual incremental reductions in emissions
of the relevant air pollutant . . . for the purposes of the applicable
NAAQS by the applicable date.'' This requirement serves as insurance
that IPT offsets must not interfere with NAAQS attainment for ozone.

    Additionally, the commenters note that the Act establishes VOC-
specific offset ratios required for ozone permitting. The IPT
provisions at issue in this rulemaking are for the NNSR permitting
offset requirement for ozone and stem from the CAA section 173(c)
requirement to offset ``increased emissions of any air pollutant''
rather than a requirement that specifically identifies the precursor at
issue.\49\ Of note, the EPA is not suggesting that a VOC-specific SIP
requirement where Congress has not permitted NOX
substitution can be satisfied by utilizing either precursor
interchangeably. Specifically, in CAA section 182(b)(1), for newly
listed Moderate and higher classified nonattainment areas, there is a
requirement that a reduction in VOC emissions of 15 percent be
achieved. In the case of a nonattainment area (Moderate and higher
classified) that has not previously achieved the 15 percent VOC ROP
reduction and is seeking to utilize NNSR permitting as one of the
methods by which it will achieve the required VOC reductions, the state
is not allowed to utilize IPT in its NNSR program.
---------------------------------------------------------------------------

    \49\ If anything, the statement in section 182(c)(2)(C)
permitting NOX substitution that ``would result in a
reduction in ozone concentrations at least equivalent to that which
would result from the amount of VOC emission reductions required
under subparagraph (B)'' evidences Congress's understanding that
NOX reductions, when properly calculated, can be utilized
to result in equivalent ozone reductions as VOC emissions; a
contention which the commenters dispute and is discussed below in
addressing the commenters' ``anti-backsliding'' comments.
---------------------------------------------------------------------------

    Comment: One commenter argued that the IPT provision for ozone
violates the CAA's anti-backsliding requirements because ``[a] rule
that allows a new major source to be constructed and emit increased
levels of a pollutant that would have been barred under prior rules is
by definition less stringent.'' Additionally, the commenter asserted
that the IPT provision would put human health at risk and fails to
assure equivalent or greater ozone reduction benefit.
    Response: The commenter did not identify any specific CAA
requirements in their comments with regard to anti-backsliding. Based
on the commenter's statement that the proposed rulemaking ``unlawfully
and arbitrarily authorize[s] controls for that pollutant that are less
stringent than required under the pre[hyphen]existing NAAQS,'' the
commenter appears to be referencing the EPA's application of section
172(e); however, this provision applies to relaxation of a prior NAAQS.
The EPA is not relaxing a prior NAAQS in this action, and thus section
172(e) does not apply.
    As the EPA has stated, the IPT approach outlined in the proposal
and being finalized here represents the longstanding policy of the
EPA.\50\ Therefore, it is not ``less stringent'' than the agency's
prior approach. Moreover, the commenter provided no analysis or support
for the assertion that this rule would allow ``a new major source to be
constructed and emit increased levels of a pollutant that would have
been barred under prior rules.''
---------------------------------------------------------------------------

    \50\ See Louisiana; Final Rule: 67 FR 61260, September 30, 2002
(proposed at 67 FR 48090, July 23, 2002); Texas; Final Rule: 71 FR
52664, September 6, 2006 (proposed at: July 23, 2001); Mass
Emissions Cap and Trade Program proposal (66 FR 38240; July 23,
2001).
---------------------------------------------------------------------------

    The EPA also disagrees with commenter's claims that the proposed
rulemaking would put human health at risk and that IPT fails to assure
equivalent or greater ozone reduction benefits. In both the proposed
and final rule, the use of any IPT ratio is predicated on a
demonstration that assures exactly that. See, e.g., 40 CFR
51.165(a)(11)(i)(B)(I) and (C). The commenter claimed that the
``proposal nowhere finds or demonstrates that any specific trading
ratios will be sufficient to assure equivalent or greater ozone
reductions in any particular ozone nonattainment areas, nor does it
specify with precision the methods and supporting data required to make
such a demonstration.'' These critiques are premature and would only be
germane if the commenter sought to dispute the approval of a specific
IPT ratio. As discussed earlier in response to comments requesting that
the EPA directly develop ratios for each nonattainment area as part of
this final rule, the EPA maintains that we cannot, and will not
endeavor to, identify all possible specific trading ratios for all
areas. Rather, the EPA has defined three different procedural
approaches for implementing IPT and provided technical guidance to
assist air agencies (and permit applicants, where applicable) in the
establishment of such ratios.
    Furthermore, the ability of an IPT ratio to assure equivalent or
greater ozone reductions has been acknowledged by Congress. CAA section
182(c)(2)(C) permits air agencies to demonstrate that substituting
NOX emissions for VOC emissions to satisfy the VOC-specific
requirements of CAA section 182(c)(2)(B) ``would result in a reduction
in ozone concentrations at least equivalent to that which would result
from the amount of VOCs emission reductions required.'' In that
context, Congress specifically authorized the substitution because it
related to a VOC-specific requirement. The IPT provisions in this final
rule, relate to the ambient air pollutant ozone, and, thus, as
discussed previously, specific authorization to substitute precursors
is not necessary as part of the section 173(c) offset requirement
because, as discussed earlier, CAA section 302(g) defines ``air
pollutant'' to include ``any precursors to the formation of any air
pollutant.'' However, section 182(c)(2)(C) is noteworthy because it
formalizes Congress' acknowledgement that, contrary to the commenter's
assertions, IPT can be implemented in a manner which assures equivalent
or greater ozone reductions.

E. Emissions Inventory and Emissions Statement Requirements

    The EPA proposed to clarify our emissions inventory and emissions
statement requirements for purposes of the 2015 ozone NAAQS by adding
40 CFR 51.1315. CAA sections 182(a)(1) and 182(a)(3)(A) require states
to submit emissions inventories to the EPA. To clarify these statutory
requirements within the context of implementing the 2008 ozone NAAQS,
the EPA added 40 CFR 51.1115 (80 FR 12264, 12314; March 6, 2015). For
purposes of the 2015 ozone NAAQS, we proposed to add 40 CFR 51.1315, to
clarify requirements for the emissions inventories required by CAA
sections 182(a)(1) and 182(a)(3)(A). We also provided a preamble
discussion in the proposed rulemaking to clarify the emissions
statement requirements of 182(a)(3)(B), and are finalizing 40 CFR
51.1315 consistent with that discussion in this final rule.
1. Emissions Inventories
    a. Summary of Proposal. The EPA proposed to retain our existing
approach to the general emissions inventory requirements for purposes
of the 2015 ozone NAAQS, as articulated in the final 2008 Ozone NAAQS
SIP Requirements Rule.\51\ We also proposed revisions to point source
reporting thresholds in the AERR (codified in 40 CFR 51, subpart A) to
be consistent with the major source thresholds for ozone nonattainment
areas.
---------------------------------------------------------------------------

    \51\ The preamble to the final 2008 Ozone NAAQS SIP Requirements
Rule provides an extensive discussion of the EPA's rationale and
approach for emissions inventories (80 FR 12289; March 6, 2015).
---------------------------------------------------------------------------

    The emissions inventory requirements for the 2008 ozone NAAQS,
found at 40 CFR 51.1115, describe the criteria and timing for base year
and periodic

inventories required under CAA sections 182(a)(1) and 182(a)(3)(A),
respectively. To support the periodic emissions inventory requirement,
the EPA proposed revisions to the AERR point source reporting
thresholds in AERR Table 1 (40 CFR 51, subpart A, appendix A) to be
consistent with the major source thresholds for ozone nonattainment
areas. These reporting thresholds are in tons of potential emissions
per year. The existing AERR Table 1 includes Moderate area thresholds
of 100 tpy for NOX and VOC, which are the same as the
triennial thresholds for all areas. The existing AERR table also
includes lower VOC thresholds for Serious, Severe and Extreme areas of
50, 25 and 10 tpy. With the proposed revision, the AERR table would be
updated to also explicitly include these same Serious, Severe and
Extreme area thresholds for NOX. The same thresholds as have
existed for VOC also apply for NOX, consistent with
definition of ``major source'' in both 40 CFR 70.2 and 40 CFR 71.2. In
addition, the emission thresholds also depend on whether the source is
within an OTR in accordance with CAA 184(b)(2). The EPA proposed to
include in the AERR table a 50 tpy potential-to-emit (PTE) VOC
threshold for sources within an OTR and a 50 tpy PTE NOX
threshold for sources both within an OTR and within a Moderate ozone
nonattainment area, proposing to apply the same definition noted
earlier in 40 CFR 70.2 and 40 CFR 71.2. Finally, the proposal removed
the 100 tpy PTE CO threshold from the AERR tables in Appendix A for
ozone nonattainment areas because there is no corresponding major
source threshold for CO in the existing or proposed implementing
regulations for the ozone NAAQS.
    b. Final Rule. The EPA is finalizing the proposed emissions
inventory requirements, with the exception of the proposed AERR Table 1
reporting threshold for NOX sources within an OTR, as
explained more fully later. In general, we are providing that air
agencies may rely, when appropriate, on their 3-year cycle inventory as
described by the AERR to meet the 182(a)(3)(A) periodic inventory
obligations, with additional requirements for the reporting of ozone
season day emissions and treatment of partial-county inventories.\52\
For all of the mobile source inventories used for 2015 ozone NAAQS
implementation, states should use the latest emissions models available
at the time that the attainment plan inventory is developed.\53\ In
general, for states other than California that choose to fulfill
various modeling requirements by using the latest EPA emissions model,
the latest approved version of the MOtor Vehicle Emissions Simulator
(MOVES) model should be used to estimate emissions from onroad and
certain nonroad transportation sources. States should use the latest
available planning emission inputs including, but not limited to,
vehicle miles traveled, speeds, fleet mix, SIP control measures and
fuels. The current version of MOVES is available at: https://www.epa.gov/moves. Other appropriate methods should be used to estimate
emissions of nonroad sources not included in the model. For California,
consult with the EPA Region 9 for information on the latest approved
version of the EMFAC (EMission FACtors) model. EMFAC2014 is the most
recently approved model.\54\
---------------------------------------------------------------------------

    \52\ States should consult the guidance document titled
``Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS)
and Regional Haze Regulations,'' EPA-454/B-17-003, July 2017, and
any subsequent updates to that guidance that the EPA may make
available at: https://www.epa.gov/air-emissions-inventories/emissions-inventory-guidance-implementation-ozone-and-particulate-matter.
    \53\ Section 172(c)(3) of the CAA requires that emissions
inventories be based on the most comprehensive, accurate and current
information available. To do so, air agencies should use the most
up-to-date method for estimating emissions.
    \54\ The EPA is aware that EMFAC2017 has been made available by
the California Air Resources Board and is currently reviewing that
model. However, EMFAC2017 should not be used for any conformity
analyses until the EPA officially approves the model for that
purpose.
---------------------------------------------------------------------------

    The EPA is finalizing the proposed updates to AERR Table 1 that
explicitly include the same Serious, Severe and Extreme area thresholds
for NOX as currently exist for VOC. We are also removing the
100 tpy PTE CO threshold from Appendix A for ozone nonattainment areas,
as proposed.
    We are not finalizing our proposal to revise the NOX
reporting threshold for sources within an OTR from 100 tpy to 50 tpy.
This revision would have aligned the NOX reporting threshold
with that for VOC sources in an OTR, which is established as 50 tpy in
CAA section 184(b)(2) and in subsection 3(ii) of the definition of
``major source'' in 40 CFR 70.2 and 40 CFR 71.2. For nonattainment
areas, CAA section 182(f)(1) applies the planning requirements for
major stationary sources of VOC to NOX sources within
nonattainment areas classified Serious and higher. Major stationary
sources of NOX for nonattainment areas are thus defined by
the same corresponding emissions thresholds for VOC sources under CAA
sections 182(c) (Serious areas, 50 tpy), 182(d) (Severe areas, 25 tpy)
and 182(e) (Extreme areas, 10 tpy). Section 184 of the CAA does not
include NOX requirements for major stationary sources of VOC
in an OTR, while CAA section 184(b)(2) specifically provides that major
stationary sources of VOC (i.e., at least 50 tpy VOC) would be subject
to requirements applicable to major stationary sources in a Moderate
nonattainment area. The EPA's proposed revision of the OTR
NOX reporting threshold was intended to establish a
parallel, consistent basis for emissions reporting requirements for VOC
and NOX sources in an OTR. However, after considering
comments received (see later), the EPA has determined that our proposal
incorrectly interpreted the interaction between CAA sections 182 and
184 as requiring a NOX reporting threshold of 50 tpy in the
OTR. CAA section 182(f) states that the planning requirements for ozone
nonattainment areas that apply to major stationary sources of VOCs will
also apply to major stationary sources of NOX, but it does
not say the major stationary source definition for VOCs (such as the 50
tpy threshold contained in 184(b)(2) for stationary sources in the OTR)
shall also apply to determining major stationary sources of
NOX. Instead, section 182(f) specifically defines major
stationary sources of NOX with reference to the general
definition contained in CAA section 302, which applies a 100 tpy
emission threshold (see 42 U.S.C. 7602(j)), and the thresholds for
Serious, Severe and Extreme nonattainment areas contained in CAA
section 182(c), (d) and (e) (i.e., 50, 25 and 10 tpy, respectively).
Interpreting CAA section 182(f) as establishing a 100 tpy threshold for
major stationary sources of NOX in the OTR is consistent
with the EPA's longstanding position regarding the interaction between
section 182 and 184.\55\ We are therefore not finalizing our proposal
to revise the NOX reporting threshold for sources within an
OTR, and are retaining the existing general NOX reporting
threshold of 100 tpy. Major stationary sources within an OTR that are
also located in ozone nonattainment areas classified Serious and higher
would be subject to the

corresponding major source thresholds for those area classifications.
---------------------------------------------------------------------------

    \55\ See 57 FR 55620, 55622 (November 25, 1992) (stating that
section 184(b)(2) ``is specifically limited to VOC sources because
section 182(f) does not refer to the section 184 definition in
describing the major stationary source definitions applicable for
NOX purposes''); Region 1 EPA New England NOX
RACT Summary (stating that for ``Marginal and Moderate nonattainment
areas and attainment areas in the OTR, a major NOX source
is one with the potential to emit 100 tpy or more of
NOX''), https://www3.epa.gov/region1/airquality/noxract.html.
---------------------------------------------------------------------------

    c. Comments and Responses. Comment: Two commenters did not support
the EPA's proposed revision of the NOX reporting threshold
for sources within an OTR from 100 tpy to 50 tpy. The commenters
contended that any changes to reporting thresholds in AERR Table 1 must
be consistent with major source definitions established in the CAA and
regulation.
    Response: We agree with the commenters and are not finalizing the
proposed revision. As discussed previously, we have determined that CAA
section 182(f) does not apply the major stationary source threshold for
VOCs contained in 184(b)(2) to major stationary sources of
NOX in an OTR.
2. Emissions Statements
    For nonattainment areas, air agencies must develop, and include in
their SIPs, emission reporting programs for certain VOC and
NOX sources in accordance with CAA section 182(a)(3)(B).\56\
The required state program defines how air agencies obtain emissions
data directly from certain facilities, and these data, along with other
information, are then reported to the EPA as part of SIP inventories
required under CAA sections 182(a)(1) and 182(a)(3)(A). This state
program is generally referred to as an emissions statement regulation,
and it outlines how certain facilities must report emissions and
facility activity data to an air agency, typically a state agency.
Reports submitted to air agencies must be accompanied by ``a
certification that the information contained'' in the report is
``accurate to the best knowledge'' of the facility.\57\ To properly
implement the emissions reporting requirements, emissions statement
regulations should be coordinated carefully with the data elements that
are required by the EPA (the existing requirements at 40 CFR 51.1115
and the requirements finalized in this rule at 40 CFR 51.1315). An air
agency must submit the emissions statement regulation required by CAA
section 182(a)(3)(B), or a written statement certifying a previously
approved regulation, to the EPA as a SIP revision for approval (see
Section III.A.2 of this preamble). CAA section 110, in conjunction with
40 CFR 51.102, 51.103 and Appendix V, establishes the procedure for
submitting a SIP revision.
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    \56\ CAA section 182(a)(3)(B)(2) allows that air agencies may
waive, with the EPA's approval, the requirement for emission
statements for classes or categories of sources with less than 25
tpy of actual plant-wide NOX or VOC emissions in
nonattainment areas, provided the class or category is included in
the base year and periodic inventories required under CAA sections
182(a)(1) and 182(a)(3)(a), respectively. Emissions in this case
must be calculated using emission factors established by the EPA, or
other methods acceptable to the EPA. We emphasize that the 25 tpy
emissions threshold applies separately for purposes of emissions
statement requirements, and does not relate to the major stationary
source reporting thresholds for emissions inventories in AERR Table
1.
    \57\ Additional details on developing emissions statement
regulations can be found in the guidance document titled ``Guidance
on the Implementation of an Emission Statement Program (DRAFT),''
(July 1992) available at: https://www.epa.gov/air-emissions-inventories/implementation-emission-statement-program.
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V. Additional Considerations

    This section addresses several important SIP-related topics for
which the EPA did not propose specific regulatory provisions due to
lingering legal issues, scientific unknowns and uncertainties
associated with developing and implementing new regulatory requirements
and/or policies. The EPA is using this final rule notice, however, to
articulate our existing requirements and policies pertaining to these
topics and to inform possible future actions.

A. Managing Emissions From Wildfire and Wildland Prescribed Fire

    a. Proposed Recommendation. The preamble to the proposal for this
rule recognized both that prescribed fires are a source of emissions
that can have a greater or lesser impact on ozone concentrations
depending on how and when the prescribed fire is conducted, and that a
prescribed fire program can be a way to reduce emissions from
catastrophic wildfires which can impact ozone concentrations. In the
preamble to the proposal, the EPA proposed to recommend, as guidance to
air agencies, that in their attainment demonstrations they account for
emissions from wildfire and wildland prescribed fire as described in
the final PM2.5 SIP Requirements Rule.
    b. Final Recommendation. The EPA continues to recommend that air
agencies use the approach described in the final PM2.5 SIP
Requirements Rule when accounting for emissions from wildfire and
wildland prescribed fire. Before explaining this recommendation
further, the EPA wishes to emphasize that this recommendation is
focused on wildland fire management. There are other uses of prescribed
fire and other types of burning that may occur in nonattainment areas,
or that may affect downwind nonattainment areas, such as burning of
land clearing debris, agricultural burning and burning of logging slash
on land where the primary purpose of the logging is for commercial
timber sale.\58\ The challenges with applying the traditional
nonattainment planning framework discussed here are particular to
wildland fire and prescribed fire on wildlands. The EPA believes that
addressing these other uses of prescribed fire does not present nearly
the same level of challenge as does addressing wildland fire, and,
thereby, can still be accommodated within the nonattainment planning
framework. For example, where these other types of burning currently
contribute to ozone levels in a nonattainment area, air agencies may,
with an adequate technical demonstration, be able to take credit for
reductions in ozone concentrations resulting from improvement in smoke
management techniques for these types of prescribed fire where the
improvement results in a demonstrated reduction in impacts in the
nonattainment area.
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    \58\ The EPA notes that some wildland logging operations are
conducted for the same purposes as prescribed fire (e.g., reducing
fuel load, ecosystem benefits). The fact that some of the removed
trees may be sold as timber does not make commercial timber sale the
primary purpose of such operations.
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    The EPA also wants to clarify that we continue to encourage
federal, state, local and tribal agencies and private land owners, to
take situation-appropriate steps to minimize impacts from prescribed
fire emissions on wildland. The EPA encourages all land owners and
managers to apply appropriate basic smoke management practices (BSMP)
to reduce emissions from prescribed fires, especially where an air
agency has determined that prescribed fires are a significant source
affecting air quality. The EPA understands that the federal land
managers (FLMs) apply these measures routinely and will be available to
consult with other agencies and private land owners interested in doing
the same.
    However, for several reasons, the EPA does not believe it would be
effective policy or technically appropriate to recommend that control
measures for wildland fire be adopted into SIPs as enforceable measures
and credited for emissions reductions (of ozone and precursors) that
would help the area attain the standard.\59\ Instead, the EPA

recommends that ozone nonattainment plans (and in particular the
attainment demonstrations) not account for expected air quality changes
over the planning period resulting from changes in the use of wildland
prescribed fire or other wildland fire management practices to reduce
future wildfires, or air quality changes over the planning period
resulting from changes in wildland fire emissions due to a program of
prescribed fire or due to any other cause, including climate change. In
most cases, state attainment demonstration modeling should assume that
wildland prescribed fire and wildfire emissions in the attainment year
will be equal to, and have the same temporal and geographic pattern as,
those assumed in the baseline inventory year.
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    \59\ These reasons include concerns raised by commenters on the
PM2.5 SIP Requirements Rule about the difficulties
associated with requiring (or even encouraging) states to
incorporate wildland fire emissions into existing nonattainment
planning procedures and practices under the CAA; high year-to-year
variability and unpredictability with emissions from wildland fires;
uncertainty in the amount of credit to give for reduced wildfire
within the planning period and in the amount of benefit that exists
after accounting for increases in prescribed fires within the
planning period; and the fact that air quality data actually
influenced by fire events may ultimately be excluded for regulatory
purposes under the provisions of the Exceptional Events Rule (40 CFR
50.14).
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    The EPA acknowledges that some level and temporal and spatial
patterns of fire emissions must still be assumed in the attainment
demonstration in order to ensure that the required air quality modeling
results in a realistic physical and chemical environment and a
correspondingly realistic model response against which to analyze the
changes from source categories where express accounting of emissions
changes is being done. This final rule does not constrain the options
for states regarding the appropriate assumptions to make for fire
emissions. Rather, the guidance in this preamble simply recommends that
once this base level is established, ozone plans should not attempt to
project changes over the planning period in emissions from wildfires or
prescribed fires on wildland within the nonattainment area, or in
upwind areas included in the modeling domain, that are due to
variability in wildfire occurrence or changes in the use of wildland
prescribed fire or other wildland fire management practices. Moreover,
the EPA anticipates that changes in spatial and temporal patterns of
wildfire will likewise be too uncertain for them to be allowed to have
the effect of reducing or increasing the control requirement on
conventional anthropogenic sources. The EPA, therefore, recommends that
wildland fire emissions generally should be held constant in the air
quality modeling over the planning period, regardless of whether
wildland fire management practices by land managers are expected, and
possibly encouraged or required, to change.
    Air agencies have flexibility in determining how best to represent
wildland fire emissions. As noted earlier, base year emissions
inventories for the nonattainment areas should represent the conditions
leading to nonattainment and be consistent with inventories used for
modeling. For fires, the EPA additionally encourages air agencies to
use a representative mix of prescribed fire and wildfire in their
inventories. Using ozone as an example, some plans under previous ozone
NAAQS have estimated the actual fire emissions and temporal and spatial
patterns from a given year and used this same estimate as part of the
assumed future baseline inventory for planning, while others have used
average emissions over multiple years. Other approaches may be
appropriate as well. Moreover, regardless of the approach used, the EPA
still encourages air agencies to submit actual wildfire and prescribed
fire activity data that are critical to developing emissions estimates
to the NEI, as suggested in the AERR.
    A consequence of the recommendation of not expressly accounting for
changes in wildland fires in attainment demonstrations is that measures
to reduce emissions from wildland fires, such as prescribed fire to
prevent catastrophic wildfires or smoke management programs and BSMP
for prescribed fires in wildland, need not be included as RACM for the
respective fire types. This is because the changes in emissions due to
such measures would not be accounted for in determining what is
necessary for attainment and/or what would advance the attainment date,
which is how the EPA is recommending that RACM be determined. So, for
example, in an area that can attain in 6 years with measures that do
not address wildland fire, the EPA does not recommend that states
attempt to quantify whether increased prescribed fire could advance the
attainment date by 1 year, due to the aforementioned difficulties
associated with such quantification.
    To be clear, nothing about this recommendation regarding RACM is
intended to suggest that prescribed fires should be ignited in wildland
(or elsewhere) without regard to the air quality or public health
consequences. As noted earlier, the EPA believes these consequences are
important to address, and intends to engage in dialogue with the FLMs,
air agencies, tribes, state and private land owners and other
stakeholders at appropriate times, such as during the process for the
development of land management plans, about how land managers determine
when and where prescribed fire is appropriate for particular wildlands
and how to identify and implement appropriate mitigation measures. The
guidance in this preamble simply makes clear the EPA's view regarding
our recommendation for RACM for wildland fires.
c. Comments and Responses
    Comment: The EPA received comments expressing agreement with the
EPA's recommended approach to managing emissions from wildfire and
wildland prescribed fires. A few commenters took positions on
specifically how to define RACM for wildfires, ranging from suggesting
that the EPA require smoke management plans to simply stating that
prescribed fires themselves are RACM with no further measures required.
Some commenters disagreed with our position that states not take credit
in the SIP for emission reductions attributable to a reduced incidence
of wildfire if the state can demonstrate that the measures in the SIP
can be expected to reduce emissions from wildfire events that would
ordinarily not be excluded from the design value for the area. Other
commenters disagreed with our recommendation that wildfire emissions be
kept constant in projections for the attainment demonstration.
    Response: In light of the fact that the EPA did not propose
specific guidance on defining RACM for wildfires and typically does not
define RACM for specific categories, and the fact that the EPA is not
recommending that states include RACM for wildland fires, we are not
providing further guidance in response to those comments. The basis for
recommending that wildfire emissions be kept constant in baseline
projections is explained earlier and is driven by the uncertainties
(e.g., patterns, timing and variability) in predicting fire emissions
that affect ozone levels in in nonattainment areas. This recommendation
is only guidance, and is not binding on the states or the EPA. In our
actions on individual SIPs, the public will have the opportunity to
make similar comments and we will consider those comments in the
context of those actions.

B. Transportation Conformity and General Conformity

1. What is conformity?
    Conformity is required under CAA section 176(c) to ensure that
federal actions are consistent with (``conform to'') the applicable
state, tribal or federal implementation plan (collectively referred to
as the SIP in the remainder

of this section). Conformity to the applicable implementation plan
means that federal activities will not cause or contribute to new
violations of the standards, worsen existing violations or delay timely
attainment of the relevant NAAQS or interim reductions and milestones.
Conformity applies to areas that are designated nonattainment and
nonattainment areas redesignated to attainment that are required to
have a CAA section 175A maintenance plan after 1990 (``maintenance
areas''). Because certain provisions of section 176(c) apply only to
highway and mass transit funding and approval actions, the EPA
published two sets of regulations to implement section 176(c).
    The EPA's Transportation Conformity Rule (40 CFR 51.390 and part
93, subpart A) establishes the criteria and procedures for determining
whether transportation activities conform to the SIP. These activities
include adopting, funding or approving transportation plans,
transportation improvement programs and federally supported highway and
transit projects. The EPA first promulgated the Transportation
Conformity Rule on November 24, 1993 (58 FR 62188), and subsequently
published several amendments. We subsequently restructured the
Transportation Conformity Rule so that existing transportation
conformity requirements apply for any new or revised NAAQS (77 FR
14979; March 14, 2012). The Transportation Conformity Rule, therefore,
does not need to be updated to reflect the 2015 ozone NAAQS. The EPA in
June 2018 issued an update to existing transportation conformity
guidance related to the implementation of the revised ozone NAAQS. The
guidance is available at: https://www.epa.gov/state-and-local-transportation/policy-and-technical-guidance-state-and-local-transportation. For further information on transportation conformity
rulemakings, policy guidance and outreach materials, see the EPA's
website at https://www.epa.gov/state-and-local-transportation.
    The EPA's general conformity regulations (40 CFR part 51, subpart W
and 40 CFR part 93, subpart B) establish the criteria and procedures
for determining whether activities not addressed by the transportation
conformity rule conform to the appropriate implementation plan. The EPA
first promulgated general conformity regulations in November 1993 (58
FR 63214; November 30, 1993)). Subsequently, the EPA finalized
revisions to the general conformity regulations on April 5, 2010 (75 FR
17254). The general conformity program ensures that federal actions not
related to highway and transit funding and approval actions will not
interfere with the appropriate implementation plan. General conformity
also fosters communications between federal agencies and state and
local air quality agencies, provides for public notification of and
access to federal agency general conformity determinations and allows
for air quality review of individual federal actions. More information
on the general conformity program is available at https://www.epa.gov/general-conformity.
2. Why is the EPA discussing transportation and general conformity in
this final rulemaking?
    The EPA is discussing transportation and general conformity in this
rulemaking in order to provide affected parties with information on
when conformity must be implemented after areas are designated
nonattainment for the 2015 ozone NAAQS. The information presented here
is consistent with existing conformity regulations and statutory
provisions that are not addressed by this ozone implementation
rulemaking. Affected parties include state, local and tribal
transportation and air quality agencies, metropolitan planning
organizations and federal agencies including the U.S. Department of
Transportation (DOT), the U.S. Department of Defense (DOD), the U.S.
Department of Interior (DOI) and the U.S. Department of Agriculture
(USDA).
3. When would transportation and general conformity apply to areas
designated nonattainment for the 2015 ozone NAAQS?
    Transportation and general conformity will apply 1 year after the
effective date of nonattainment designations for the 2015 ozone NAAQS.
CAA section 176(c)(6) provides a 1-year grace period from the effective
date of initial designations for any new or revised NAAQS before
transportation and general conformity apply in nonattainment areas. The
grace period applies even if the area had been designated nonattainment
for a prior ozone NAAQS. For additional information on transportation
conformity requirements and the 1-year grace period please refer to the
EPA's transportation conformity guidance for the 2015 ozone NAAQS
available at: https://www.epa.gov/state-and-local-transportation/policy-and-technical-guidance-state-and-local-transportation.
    As discussed in Section II of this preamble, the EPA proposed and
sought comment on two alternative approaches for revoking the 2008
ozone NAAQS for all purposes and, where applicable, establishing anti-
backsliding requirements. We are not taking any final action regarding
an approach for revoking a prior ozone NAAQS and establishing anti-
backsliding requirements; the EPA intends to address any revocation of
the 2008 ozone NAAQS and any potential anti-backsliding requirements in
a separate future rulemaking. We note here that the CAA requires
transportation and general conformity determinations in areas that are
designated nonattainment or maintenance for a given pollutant and
standard, which at this time includes the 2008 ozone NAAQS.
4. Are there any other impacts related to general conformity based on
implementation of the 2015 ozone NAAQS?
    As air agencies develop SIP revisions for the 2015 and future ozone
NAAQS, the agency recommends that state and local air quality agencies
work with federal agencies with large facilities (e.g., commercial
airports, ports and large military bases) that might take actions
subject to the general conformity regulations to establish an emissions
budget in the SIP for those facilities in order to facilitate future
general conformity determinations. Such a budget could be used by
federal agencies in determining conformity or identifying mitigation
measures for particular projects at those facilities, but only if the
budget level is included and identified in the SIP.
    In a few cases, tracts of land under federal management may also be
included in nonattainment and maintenance area boundaries. The role of
prescribed fire in these areas should be assessed in concert with those
federal land management agencies. In such areas the EPA encourages air
agencies to consider including, in any baseline, modeling and SIP
attainment inventory used and/or submitted, emissions expected from
projects subject to general conformity, including emissions from
wildland fire that may be reasonably expected in the area. Where
appropriate, air agencies may consider developing plans for addressing
wildland fires in collaboration with land managers and owners.
Information is available from DOI and USDA Forest Service on the
ecological role of fire and on smoke management programs and BSMP.\60\
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    \60\ USDA Forest Service and Natural Resources Conservation
Service, Basic Smoke Management Practices Tech Note, October 2011,
available at: http://www.nrcs.usda.gov/internet/FSE_DOCUMENTS/stelprdb1046311.pdf.

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C. Requirements for Contingency Measures in the Event of Failure To
Meet a Milestone or To Attain

1. Summary of Proposal
    For purposes of the 2015 ozone NAAQS, the EPA proposed no changes
to the requirements for contingency measures articulated in the final
2008 Ozone NAAQS SIP Requirements Rule (80 FR 12285; March 6, 2015). As
required by the CAA, states must include in their nonattainment area
SIPs contingency measures that are consistent with CAA section
172(c)(9). For areas classified Serious or higher, states must also
include contingency measures that are also consistent with CAA section
182(c)(9), with a limited exception for Extreme nonattainment areas
relying on plan provisions approved under CAA section 182(e)(5).
2. Final Rule
    The EPA is finalizing the proposed requirements. Contingency
measures required under CAA sections 172(c)(9) and 182(c)(9) must be
fully adopted rules or measures that can take effect without further
action by the state or the EPA upon failure to meet milestones or
attain by the attainment deadline. Per the EPA guidance,\61\ these
measures should provide 1 year's worth of emissions reductions, or
approximately 3 percent of the baseline emissions inventory. Once
triggered, if these adopted contingency measures are insufficient to
attain the standard, an air agency must conduct additional control
measure development and implementation for the area as necessary to
correct the shortfall.
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    \61\ ``Guidance on Issues Related to 15 Percent Rate-of-Progress
Plans,'' Memorandum from Michael H. Shapiro, Acting Assistant
Administrator for Air and Radiation, to Regional Air Directors
(August 23, 1993), available at: http://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/19930823_shapiro_15pct_rop_guidance.pdf.
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    Regarding content of the 1 year's worth of reductions covered by
the contingency measures, the EPA is continuing to allow contingency
measure emissions reductions to be based entirely or in part on
NOX controls if the area has completed the initial 15
percent ROP VOC reduction required by CAA section 182(b)(1)(A)(i) and
an air agency's analyses have demonstrated that NOX
substitution (entirely or in part) would be effective in bringing the
area into attainment.
    With respect to Extreme ozone nonattainment areas, CAA section
182(e)(5) allows the agency to exercise discretion in approving Extreme
area attainment plans that rely, in part, on the future development of
new control technologies or improvements of existing control
technologies, where certain conditions are met. This discretion can be
applied as long as an air agency has demonstrated that: All RACM,
including RACT, have been included in the plan; the area's RFP
demonstration during the first 10 years after designation does not rely
on anticipated future technologies; and the air agency has submitted
enforceable commitments to timely develop and adopt contingency
measures to be implemented if the anticipated future technologies do
not achieve planned reductions. The EPA is continuing to allow air
agencies to submit, for Extreme nonattainment areas, enforceable
commitments to develop and adopt contingency measures meeting the
requirements of 182(e)(5) to satisfy the requirements for attainment
contingency measures in CAA sections 172(c)(9) and 182(c)(9). These
enforceable commitments must obligate the air agency to submit the
required contingency measures to the EPA no later than 3 years before
any applicable implementation date, in accordance with CAA section
182(e)(5).\62\ We note that this does not, however, relieve air
agencies from obligations to submit contingency measures as required by
CAA sections 172(c)(9) and 182(c)(9) for periods in the first 10 years
after designation.
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    \62\ For example, where a state intends to rely on CAA section
182(e)(5) commitments to satisfy the CAA section 182(c)(9)
contingency measure requirement for an RFP milestone in year 2027,
the commitments must obligate the state to submit adopted
contingency measures to the EPA no later than 2024 (i.e., 3 years
before RFP contingency measures for 2027 would be implemented).
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    As noted in the November 17, 2016, proposed rulemaking, the EPA
acknowledges that the U.S. Court of Appeals for the Ninth Circuit
issued an opinion in Bahr v. EPA, 836 F.3d 1218 (9th Cir. 2016), cert.
denied, 199 L. Ed. 2d 525, 2018 U.S. LEXIS 58 (Jan. 8, 2018), which
rejected the EPA's longstanding interpretation of CAA section 172(c)(9)
in the context of a SIP for particulate matter standards that allowed
states to rely on control measures that are already in effect as a
valid means to meet the contingency measure requirement. The EPA does
not currently plan to alter the agency's longstanding interpretation
outside of the Ninth Circuit, especially in light of a prior decision
from the U.S. Court of Appeals for the Fifth Circuit upholding that
interpretation. See Louisiana Envt'l Action Network v. EPA, 382 F.3d
575 (5th Cir. 2004) (LEAN); see also 40 CFR 56.5(b).
3. Comments and Responses
    Comment: A commenter noted that the EPA acknowledges the Bahr v.
EPA decision, but declines to abide by it. The commenter asserts that
Bahr was properly decided, and the EPA must follow it with regards to
contingency measures required under CAA sections 172(c)(9), 182(c)(9)
and 182(e)(5).
    Response: The appropriateness of relying on already-implemented
reductions to meet the contingency measures requirement has been
addressed in two federal circuit court decisions. See LEAN, 382 F.3d at
586; Bahr, 836 F.3d 1218. The EPA believes that the language of
sections 172(c)(9) and 182(c)(9) is ambiguous with respect to this
issue, and that it is reasonable for the agency to interpret the
statutory language to allow approval of already implemented measures as
contingency measures, so long as they meet other parameters such as
providing excess emissions reductions that the state has not relied
upon to make RFP or for attainment in the nonattainment plan for the
NAAQS at issue. Until the Bahr decision, under the EPA's longstanding
interpretation of CAA section 172(c)(9) and 182(c)(9), states could
rely on control measures that were already implemented (so called
``early triggered'' contingency measures) as a valid means to meet the
Act's contingency measures requirement. The Ninth Circuit decision in
Bahr has created a split among the federal circuit courts, with the
Fifth Circuit upholding the agency's interpretation of section
172(c)(9) to allow early triggered contingency measures and the Ninth
Circuit rejecting that interpretation.
    States located in circuits other than the Ninth may elect to rely
on the EPA's longstanding interpretation of section 172(c)(9) allowing
early triggered measures to be approved as contingency measures, in
appropriate circumstances. The EPA's revised Regional Consistency
regulations pertaining to SIP provisions authorize the agency to follow
this interpretation of section 172(c)(9) in circuits other than the
Ninth. See 40 CFR part 56. To ensure that early triggered contingency
measures appropriately satisfy all other relevant CAA requirements, the
EPA will carefully review each such measure contained in an air
agency's submission, and intends to consult with air agencies
considering such measures early in the attainment plan development
process.

D. Background Ozone

    With respect to the larger issue of background ozone (or U.S.
background (USB)), the EPA has solicited input from air agencies,
tribes and interested stakeholders on aspects of USB that are relevant
to attaining the 2015 ozone NAAQS in a manner consistent with the
provisions of the CAA.\63\ To establish a common understanding and
foundation for discussion, the EPA released a white paper titled,
``Implementation of the 2015 Primary Ozone NAAQS: Issues Associated
with Background Ozone'' in December 2015, and held a workshop in
February 2016 to discuss information in the white paper.\64\ Workshop
attendees included representatives of state, local and tribal air
agencies and other interested stakeholders. General concerns expressed
by attendees that commented were that the EPA is underestimating the
magnitude and effects of USB, that available policy solutions do not
provide meaningful relief from nonattainment designations in affected
areas, and that USB can make meeting nonattainment area requirements
unreasonably difficult or costly.\65\
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    \63\ For purposes of NAAQS implementation, the EPA considers USB
to be any ozone formed from sources or processes other than U.S.
manmade emissions of NOX, VOCs, methane and CO.
    \64\ The white paper and other workshop details are available
at: https://www.epa.gov/ozone-pollution/background-ozone-workshop-and-information.
    \65\ A high-level summary of workshop feedback is available at:
https://www.epa.gov/sites/production/files/2016-03/documents/bgo3-high-level-summary.pdf. Additional written comments from interested
parties are located in a separate EPA docket available at http://www.regulations.gov (Docket ID No. EPA-HQ-OAR-2016-0097).
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    The EPA continues to engage with stakeholders and the academic
community to refine and conduct national and global model simulations
to better characterize USB, and is actively evaluating the need for
further guidance and/or rules to address USB based on feedback received
and new understandings that may emerge from ongoing research and
analysis. In 2017 and 2018, the EPA activities include participation in
the Background Ozone Science Assessment organized by the Western States
Air Resources Council, the Western Regional Air Partnership and the
American Petroleum Institute,\66\ the United Nations' Hemispheric
Transport of Air Pollutants task force \67\ and the U.S. National Air
and Space Administration's Health and Air Quality Applied Sciences
Team.\68\ Each of these efforts includes workshops for stakeholders and
development of scientific products that inform the EPA's understanding
of USB. However, the EPA is not adopting requirements regarding
background ozone with this rulemaking.
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    \66\ A summary of this Background Ozone Science Assessment
workshop is available at: https://www.wrapair2.org/pdf/BOSA_March_28-29_workshop_agenda.pdf. A related journal article is
currently undergoing peer review.
    \67\ A work plan and list of publications is available on the
website: www.htap.org.
    \68\ Details about these Health and Air Quality Applied Sciences
Team workshops and projects are available on the website: https://haqast.org.
---------------------------------------------------------------------------

    The EPA also in 2016 recently finalized revisions to the
Exceptional Events Rule to further facilitate review and approval of
exceptional events that contribute to USB, such as stratospheric ozone
intrusions and wildfires (81 FR 68216; October 3, 2016). Guidance is
currently available for demonstrations of exceptional events for high
wind dust, and the EPA finalized guidance for ozone associated with
wildfire events in September 2016.\69\ The EPA expects to make
available similar guidance for stratospheric ozone intrusions by the
end of 2018. However, the EPA is not revising the Exceptional Events
Rule or guidance with this rulemaking.
---------------------------------------------------------------------------

    \69\ Guidance documents and more information about exceptional
events can be found at: https://www.epa.gov/air-quality-analysis/exceptional-events-rule-and-guidance.
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E. Additional Policies and Programs for Achieving Emissions Reductions

1. Multi-Pollutant Planning
    Increasingly, state air agencies are considering multi-pollutant
emission reduction strategies. States have expressed interest in a
number of those strategies, ranging from energy efficiency and
renewable energy (EE/RE) programs to land use planning and travel
efficiency programs. This section discusses EE/RE, and Sections E.2 and
E.3 that follow discuss the latter programs.
    In recent years, states have expressed increased interest in EE/RE
programs when assessing compliance options for ozone RFP and attainment
demonstration SIPs. Many states are already implementing cost-effective
EE/RE requirements that reduce all types of power generation-related
emissions (including NAAQS-related air pollutants such as
NOX, PM2.5, and sulfur dioxide (SO2)
and other air pollutants, such as hazardous air pollutants).
Effectively assessing these approaches will require strong working
relationships between state energy and environmental officials. As
state public utility commissions (PUCs) and state energy offices
implement, increase the stringency of or adopt new EE/RE requirements,
their expertise can assist air agencies to incorporate the
NOX emission impacts into ozone RFP and attainment
demonstration SIPs.
    States and other authorities have requested the EPA's assistance in
accounting for the emissions reductions achieved through EE/RE programs
in NAAQS SIPs and tribal implementation plans (TIPs), and the EPA has
responded to those requests by developing several resources, including
the ``Roadmap for Incorporating EE/RE Programs and Policies in NAAQS
SIPs/TIPs'' (released August 2012) \70\ and the AVoided Emissions
geneRation Tool (AVERT), a tool for quantifying NOX,
SO2 and CO2 avoided emissions (released February
2014).\71\ The Roadmap describes four pathways (baseline emissions
projection, control strategy, emerging/voluntary measures and weight of
evidence determination) by which EE/RE policies and programs could be
included in a SIP. Each pathway is appropriate in certain circumstances
(existing vs. new EE/RE, control vs. voluntary measures etc.) and the
Roadmap can help decision-makers consider their options as they decide
which pathway(s) to pursue for incorporating EE/RE policies and
programs into SIP/TIP demonstrations. The Roadmap's Appendix I also
presents several methods available for quantifying the avoided
NOX emissions from fossil fuel generation as a result of
electricity savings from EE/RE policy/program implementation.\72\
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    \70\ Roadmap for Incorporating EE/RE Programs and Policies in
NAAQS SIPs/TIPs available at: https://www.epa.gov/sites/production/files/2016-05/documents/eeremanual_0.pdf.
    \71\ AVERT available at: http://www3.epa.gov/avert/.
    \72\Available at https://www.epa.gov/sites/production/files/2016-05/documents/appendixi_0.pdf.
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    The EPA's tool, AVERT, can help planners in quantifying the
emissions reductions that result from EE/RE policies and programs.
AVERT outputs are readily available for Sparse Matrix Operator Kernel
Emissions formatting to incorporate the emission impacts into air
quality models.
    The EPA recognizes that states may now have at their disposal other
quantification tools. An update of the ``Air Emissions Inventory
Guidance for Implementation of Ozone and Particulate Matter NAAQS and
Regional Haze Regulations'' (released July 2017) provides examples of
tools that states can use to quantify the power sector emissions and
EE/RE.\73\ In this guidance, the EPA does not limit the types of tools
states can use, so long as

states appropriately document their assumptions.
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    \73\ Available at: https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate.
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    State PUCs, primarily through their utilities, have in recent years
been rapidly increasing resources devoted to EE programs. In the 5
years spanning 2006 to 2011, budgets for EE programs more than tripled,
from $1.6 billion to $5.9 billion. Additionally, EE spending is
projected to continue to grow at a substantial rate.\74\ As of March
2015, 23 states have mandatory energy efficiency requirements, two
states have voluntary targets, and two states allow energy efficiency
as a compliance option for their renewable portfolio standard
(RPS).\75\
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    \74\ American Council for an Energy-Efficient Economy (ACEEE)
2013 State Energy Efficiency Scorecard (November 2013), available
at: http://www.aceee.org/state-policy/scorecard/.
    \75\ U.S. EPA 2015. Energy and Environmental Guide to Action,
Chapter 4 available at: https://www.epa.gov/statelocalenergy/energy-and-environment-guide-action-chapter-4-energy-efficiency-policies.
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    Also, state-level RE requirements have been implemented in 29
states plus Washington, DC, representing all regions of the
country.\76\ Between the years 2020 and 2030, many state-level RPS
programs require electric utilities to serve from 15 to 40 percent of
their retail sales with renewable power.\77\
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    \76\ RE requirements include Renewable Portfolio Standards or
state-enacted RE requirements on a Mega-Watt (MW) basis. Database of
State Incentives for Renewables and Efficiency, March 2013,
available at: http://www.dsireusa.org.
    \77\ U.S. EPA. 2015 Energy and Environment Guide to Action,
Chapter 5 available at: https://www.epa.gov/statelocalenergy/energy-and-environment-guide-action-chapter-5-renewable-portfolio-standards.
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    To further help states assess the effects of these programs, the
EPA developed a counterfactual EE/RE scenario for two areas that were
nonattainment for the 2008 ozone NAAQS, including the New York-New
Jersey-Connecticut area.\78\ In these illustrative examples the EPA
used AVERT to approximate the potential emissions that would have been
emitted into the atmosphere without current state-level EE/RE
requirements. For the New York-New Jersey-Connecticut area, the EPA
estimated that the current state-level RE requirements \79\ will avoid
over 24 tons per summer day of NOX in 2020, and the current
state-level EE programs \80\ will avoid nearly 17 tons per summer day
of NOX in 2020.\81\
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    \78\ This area encompasses eight counties in New York, 12
counties in New Jersey and three counties in Connecticut. The EPA's
analysis is described in the Technical Support Document
``Demonstrating NOX Emission Reduction Benefits of State-
Level Renewable Energy and Energy Efficiency Policies,'' available
in the docket for this rulemaking.
    \79\ The 2020 RE requirements in each state are different and
range from 20 percent to 30 percent.
    \80\ The EE programs used in each state are different.
Connecticut's estimated annual efficiency savings is 2.8 percent,
New York's target was 15 percent savings from baseline by 2015 and
New Jersey incentivized efficiency improvements through a funding
program of $265 million in FY2014.
    \81\ For context, the RFP plan for the New York-New Jersey-
Connecticut 1997 ozone NAAQS nonattainment area included a 2008
NOX emissions projection of 269 tons per summer day.
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2. Land Use Planning
    Air agencies may also wish to consider strategies that foster more
efficient urban and regional development patterns as a long-term air
pollution control measure. Resources include the U.S. Department of
Housing and Development-DOT-EPA Partnership for Sustainable
Communities, as well as the policy and technical guidance documents on
land use and related travel efficiency available on the EPA's Office of
Transportation and Air Quality website.\82\ These documents provide
communities with the information they need to better understand the
link between air quality, transportation and land use, and how certain
land use policies have the potential to help local areas achieve and
maintain healthy air quality. The documents also include methods to
help communities account for the air quality benefits of their local
land use in their air quality plans.
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    \82\ See http://www.epa.gov/otaq/stateresources/policy/pag_transp.htm.
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    If wildfire impacts are significant in a particular area, air
agencies and communities may be able to lessen the impacts of wildfires
by working collaboratively with land managers and land owners to employ
various mitigation measures including taking steps to minimize fuel
loading in areas vulnerable to fire.
3. Travel Efficiency
    Areas may also consider incorporating in their SIPs travel
efficiency strategies, such as new or expanded mass transit options,
commuter strategies, system operations (e.g., ramp metering), pricing
(e.g., parking fees, congestion pricing, roadway tolls), real-time
travel information and multimodal freight strategies. The EPA has
released several documents that could be useful to air agencies that
want to evaluate emissions reductions from travel efficiency
strategies. These documents provide information on analysis methods and
the potential effectiveness of different combinations of travel
efficiency measures for reducing emissions. Additionally, the EPA has
compiled a report about transportation control measures that have been
implemented across the country for a variety of purposes, including
reducing emissions related to criteria pollutants. All of these
documents are available on the EPA's Office of Transportation and Air
Quality website.\83\
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    \83\ See https://www.epa.gov/state-and-local-transportation/policy-and-technical-guidance-state-and-local-transportation.
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F. Additional Requirements Related to Enforcement and Compliance

    CAA section 172(c)(6) requires nonattainment SIPs to ``include
enforceable emission limitations, and such other control measures,
means or techniques . . . as well as schedules and timetables for
compliance, as may be necessary or appropriate to provide for
attainment . . .'' The EPA's ``Guidance on Preparing Enforceable
Regulations and Compliance Programs for the 15 Percent Rate-of-Progress
Plans'' (EPA-452/R-93-005, June 1993) \84\ is still relevant to rules
adopted for SIPs under the 2015 ozone NAAQS and should be consulted for
purposes of developing appropriate enforceable nonattainment plan
provisions under CAA section 172(c)(6). The EPA did not propose, and is
not adopting, any additional specific regulatory provisions related to
compliance and enforcement for implementing the 2015 ozone NAAQS, and
received no adverse comments on the existing recommended approach and
related guidance.
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    \84\ Available at: http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=00002TCM.txt.
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G. Applicability of Final Rule to Tribes

    Section 301(d) of the CAA authorizes the EPA to approve eligible
Indian tribes to implement provisions of the CAA on Indian reservations
and other areas within the tribes' jurisdiction.\85\ The Tribal
Authority Rule (TAR) (40 CFR part 49.1-49.11), which implements CAA
section 301(d), sets forth the criteria and process for tribes to apply
to the EPA for eligibility to administer CAA programs (40 CFR 49.6,
49.7). As discussed in detail in the proposed 2008

Ozone NAAQS SIP Requirements Rule (78 FR 34209; June 6, 2013), tribes
are not required to submit TIPs under the TAR. However, should a tribe
choose to develop a TIP, this rule is intended to serve as a guide for
addressing key implementation issues for areas of Indian country,
particularly for any areas of Indian country that may be designated as
nonattainment areas separate from surrounding state areas.
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    \85\ On January 17, 2014, the United States Court of Appeals for
the District of Columbia Circuit issued a decision vacating the
EPA's 2011 rule titled ``Review of New Sources and Modifications in
Indian Country'' (76 FR 38748) with respect to non-reservation areas
of Indian country (See, Oklahoma Department of Environmental Quality
v. EPA, 740 F.3d 185 (D.C. Cir. 2014)). Under the court's reasoning,
with respect to CAA SIPs, a state has primary regulatory
jurisdiction in non-reservation areas of Indian country (i.e.,
Indian allotments located outside of reservations and dependent
Indian communities) within its geographic boundaries unless the EPA
or a tribe has demonstrated that a tribe has jurisdiction over a
particular area of non-reservation Indian country within the state.
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    It is important for state and local air agencies and tribes to work
together to coordinate planning efforts where nonattainment areas
include both Indian country and state land. States need to incorporate
Indian country emissions in their base emissions inventories if Indian
country is part of an attainment or nonattainment area. Tribes and
states should coordinate their planning activities as appropriate to
ensure that neither is adversely affecting attainment of the NAAQS in
the area as a whole. Coordinated planning in these areas will help
ensure that the planning decisions made by the state and local air
agencies and tribes complement each other and that the nonattainment
area makes reasonable progress toward attainment and ultimately attains
the 2015 ozone NAAQS. In reviewing and approving individual TIPs and
SIPs, we will determine if together they are consistent with the
overall air quality needs of an area.
    States have an obligation to notify other states in advance of any
public hearing(s) on their state plans if such plans will significantly
impact such other states. 40 CFR 51.102(d)(5). Under CAA section 301(d)
and the TAR, tribes may become eligible to be treated in a manner
similar to states (TAS) for this purpose (40 CFR 49.6-49.9). Affected
states and tribes with approved TAS must also be informed of the
contents of such state plans and given access to the documentation
supporting these plans. In addition to this mandated process, we
encourage states to extend the same notice to all affected tribes,
regardless of their TAS status.
    Executive Orders and the EPA's Indian policies generally call for
the EPA to coordinate and consult with tribes on matters that affect
tribes. Executive Order 13175, titled, ``Consultation and Coordination
with Indian Tribal Governments'' requires the EPA to develop a process
to ensure ``meaningful and timely input by tribal officials in the
development of regulatory policies that have Tribal implications.'' In
addition, the EPA's policies include the agency's 1984 Indian Policy
relating to Indian tribes and implementation of federal environmental
programs, the February 2014 ``OAR Handbook for Interacting with Tribal
Governments'' and the ``EPA Policy on Consultation and Coordination
with Indian Tribes.'' \86\ Consistent with these policies, the EPA
intends to meet with tribes on activities potentially affecting the
attainment and maintenance of the 2015 ozone NAAQS in Indian country,
including our actions on SIPs. As such, it would be helpful for states
to work with tribes whose land that is part of the same general air
quality area during the SIP development process and to coordinate with
tribes as they develop their SIPs, regardless of whether the tribe's
area of Indian country is separately designated.
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    \86\ Tribal guidance documents are available at: https://www.epa.gov/sites/production/files/2018-01/documents/oar_handbook_updated_1.24.18_.pdf and http://www.epa.gov/tribal/forms/consultation-and-coordination-tribes.
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VI. Environmental Justice Considerations

    The EPA believes this action does not have disproportionately high
and adverse human health or environmental effects on minority, low-
income or indigenous populations because it does not negatively affect
the level of protection provided to human health or the environment
under the 2015 ozone NAAQS, which are set at levels to protect
sensitive populations with an adequate margin of safety.\87\ These
regulations help clarify the SIP requirements and the NNSR permitting
requirements to be met by air agencies in order to attain the 2015
ozone NAAQS as expeditiously as practicable. These requirements are
designed to protect all segments of the general population and do not
adversely affect the health or safety of minority, low-income or
indigenous populations.
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    \87\ The EPA conducted a regulatory impact analysis (RIA) of its
final action establishing the 2015 ozone NAAQS. The demographic
analysis conducted as part of the RIA found that in areas with poor
air quality relative to the revised standards, the representation of
minority populations was slightly greater than in the U.S. as a
whole (see Chapter 9, section 9.10 and Appendix 9A of the RIA).
Because the air quality in these areas does not currently meet the
revised standards, populations in these areas would be expected to
benefit from implementation of the strengthened standards. The RIA
is available at https://www3.epa.gov/ttn/ecas/docs/20151001ria.pdf
and in the RIA docket (EPA-HQ-OAR-2013-0169).
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    Comment: One commenter on the proposed rulemaking stated that the
implementation rule must identify specific measures directed to
minority, low-income and/or indigenous people. The commenter noted that
the EPA identified such measures in the PM2.5 SIP
Requirement Rule. The commenter requests that the EPA require states to
utilize specific measures when developing attainment plans, updating
yearly monitoring plans and initiating the permitting process for
overburdened communities.
    Response: The EPA is not making any changes to its proposed
approach in response to the commenter's request that the EPA require
states to utilize specific measures directed to minority, low-income
and indigenous people to help address ground-level ozone. In the CAA's
framework of cooperative federalism, states are primarily responsible
for developing plans for achieving NAAQS in areas within their
jurisdiction, based on planning rules and guidance promulgated by the
EPA. These planning requirements include (but are not limited to)
provisions for implementing emissions controls, tracking progress
toward attainment and monitoring and reporting air quality data, with
the overarching goal of attaining and maintaining the NAAQS as
expeditiously as practical, but no later than the CAA's maximum
attainment date. In the PM2.5 SIP Requirements Rule, the EPA
encouraged states to consider various tools to help users identify
areas with minority and/or low-income populations, potential
environmental quality issues, a combination of environmental and
demographic indicators that is greater than usual and other factors
that may be of interest. The EPA included these tools in the
PM2.5 SIP Requirements Rule because areas designated
nonattainment for the PM2.5 standards can contain sources of
directly emitted pollutants that can have adverse impacts on a local
neighborhood scale. By contrast, elevated levels of ambient ozone are
the result of secondary urban-scale atmospheric formation involving
emissions from ubiquitous sources of ozone precursors (VOC and
NOX) including motor vehicles, large and small industrial
processes and consumer products which result in more regional scale
impacts further down wind. The EPA encourages states to work with
communities to develop ozone-related control strategies that most
effectively reduce emissions that contribute to elevated ozone levels.

VII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders
can be found at http://www2.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is a significant regulatory action that was submitted
to the Office of Management and Budget (OMB) for review. Any changes
made in response to OMB recommendations have been documented in the
docket.

B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs

    This action is not subject to Executive Order 13771 because this
final rule is expected to result in no more than de minimis costs.

C. Paperwork Reduction Act (PRA)

    The information collection activities in this final rule have been
submitted for approval to OMB under the PRA. The ICR document that the
EPA prepared has been assigned the EPA ICR No. 2347.03 and OMB
Reference No. 2060-0695. You can find a copy of the ICR in the docket
for this rule, and it is briefly summarized here. The information
collection requirements are not enforceable until OMB approves them.
    The EPA is finalizing these implementing regulations for the 2015
ozone NAAQS so that air agencies will know what CAA requirements apply
to their nonattainment areas when the air agencies develop their SIPs
or SIP revisions for attaining and maintaining the NAAQS. The intended
effect of these implementing regulations is to provide certainty to air
agencies regarding their planning obligations. For purposes of analysis
of the estimated paperwork burden,\88\ the EPA assumed 57 nonattainment
areas,\89\ some of which must prepare an attainment demonstration as
well as submit an RFP and RACT SIP. The attainment demonstration
requirement appears in 40 CFR 51.1308, which implements CAA subsections
172(c)(1), 182(b)(1)(A) and 182(c)(2)(B). The RFP SIP submission
requirement appears in 40 CFR 51.1310, and the RACT SIP submission
requirement appears in 40 CFR 51.1312, which implements CAA subsections
172(c)(1) and 182(b)(2), (c), (d), and (e).
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    \88\ Burden is defined at 5 CFR 1320.3(b).
    \89\ The EPA developed a hypothetical list of nonattainment