emissions inventory are consistent with one another, as required by the
2008 Ozone SRR: Both inventories use actual emissions as reported to
the District by larger point sources, and emissions for other sources
(stationary area sources, areawide sources, and mobile sources) in the
2011 baseline inventory are back-casted from the 2012 base year
inventory.\149\
---------------------------------------------------------------------------

    \147\ 2018 SIP Update, 5, 11.
    \148\ Id. at 5.
    \149\ Id.
---------------------------------------------------------------------------

    Table 5 presents a summary of the 2011 RFP baseline inventory and
the updated 2017 RFP milestone inventory.

                     Table 5--Summary of Ozone Precursor Summer Emissions for 2011 and 2017
----------------------------------------------------------------------------------------------------------------
                                                         2011                                2017
             Source category             -----------------------------------------------------------------------
                                              NOX (tpd)        VOC  (tpd)         NOX (tpd)        VOC  (tpd)
----------------------------------------------------------------------------------------------------------------
Stationary Sources......................               1.7               1.3               1.3               1.2
Area Sources............................               0.7               8.4               0.2               5.7
On-road Mobile Sources..................              11.3               4.5               6.5               3.1
Non-road Mobile Sources.................               9.2               5.2               7.1               3.5
rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr
    Total for Imperial County...........              23.0              19.5              15.2              13.5
----------------------------------------------------------------------------------------------------------------
Source: 2018 SIP Update, Table II-1 (noting that numbers may not add up due to rounding) and App. A, A-3 to A-6.

    The 2018 SIP Update's RFP demonstration calculates future year VOC
targets from the 2011 baseline, consistent with CAA 182(b)(1), which
requires a 15% reduction in VOC within six years of the RFP baseline
year for a Moderate ozone nonattainment area as shown in Table 6.

                 Table 6--Rate of Progress Demonstration
------------------------------------------------------------------------
                                       VOC (tpd, unless otherwise noted)
                                     -----------------------------------
                                            2011              2017
------------------------------------------------------------------------
1. Baseline VOC.....................              19.5              13.5
2. Transportation conformity safety   ................               0.8
 margin \a\.........................
3. Baseline VOC + safety margin       ................              14.3
 (Line 1 + Line 2)..................
4. Required VOC emission reduction,   ................               15%
 % \b\..............................
5. Target VOC Level (Line 1 (2011)-   ................              16.6
 Line 4 (2017) x Line 1 (2011)).....
6. Apparent Surplus in VOC emission   ................               2.3
 reductions (Line 5-Line 3) \c\.....
7. Apparent Surplus in VOC emission   ................             11.7%
 reductions, % (Line 6/Line 1
 (2017)) \c\........................
RFP Met?............................  ................               YES
------------------------------------------------------------------------
Note: This table is adapted from the 2018 SIP Update, Table II-2 and
  CARB's Technical Clarification Letter, Attachment A.
\a\ CARB Technical Clarification Letter, Attachment A.
\b\ While the 2018 SIP Update characterizes the % change as (VOC or
  NOX), in fact, the required change is just for VOC, per our discussion
  of the ROP requirement herein.
\c\ The CARB Technical Clarification Letter identifies 2.2 tpd and 11.4%
  as the apparent surplus in VOC emission reductions. The difference
  between the values in the CARB Technical Clarification Letter and this
  table is due to rounding. Numbers listed here in Table 6 are
  calculated as shown in the table.

    CARB concludes that the RFP demonstration for Imperial County in
the 2018 SIP Update meets the CAA's applicable requirements for RFP.
3. EPA Review of State's Submission
    We have reviewed the portions of the 2018 SIP Update relating to
Imperial County, including the 2011 baseline and 2017 emissions
inventories and the updated RFP demonstration that uses a 2011 baseline
year, and CARB's Technical Clarification Letter for consistency with
CAA and regulatory requirements and EPA guidance. Based on our review
of the emissions inventory documentation in the 2018 SIP Update, as
well as the Imperial Ozone Plan, we find that CARB and the District
used the most recent planning and activity assumptions, emissions
models, and methodologies in developing the RFP baseline and milestone
year inventories.
    Regarding the 2008 Ozone SRR's requirement that the base year
inventory be consistent with the baseline year for

the RFP demonstration, we note that 2012 is the year used for the base
year inventory, while 2011 is the year used for the baseline inventory
for the RFP demonstration. However, both the 2012 base year inventory
and 2011 RFP baseline inventory use actual emissions reported by larger
point sources, and, for other sources (e.g., stationary area sources,
areawide sources, and mobile sources), the 2011 RFP baseline inventory
is back-casted from the 2012 base year inventory, and therefore based
on the same data. Therefore, we find that selection of 2012 as the base
year for the emissions inventory is consistent with the 2011 baseline
year for the RFP demonstration for this nonattainment area as required
by 40 CFR 51.1115(a).
    In addition to the 2011 RFP baseline inventory, the 2018 SIP Update
also includes an inventory for the RFP milestone year of 2017. Similar
to the 2011 RFP baseline inventory, the 2017 RFP milestone inventory
includes actual emissions reported for 2017 for certain stationary
sources and forecasted emissions for other sources using updated
activity data, where available. The 2017 RFP milestone inventory from
the 2018 SIP Update (13.5 tpd of VOC) is smaller than the 2017
emissions inventory from the Imperial Ozone Plan (16.85 tpd of VOC).
These emission inventory updates are directionally consistent with the
observed 2015-2017 design value of 77 ppb as compared to the modeled
2015-2017 design value of 79 ppb and suggest that Imperial County made
greater progress towards attaining the 2008 ozone NAAQS than was
originally predicted, even though the area did not actually attain the
standards.
    We also reviewed the calculations in Table II-2 of the 2018 SIP
Update and CARB's Technical Clarification Letter, Attachment A, as
presented in Table 6 of this proposed rule, and find that CARB and the
District used an appropriate calculation method to demonstrate RFP.
Specifically, we reviewed the 2011 and 2017 emissions inventories
included in the 2018 SIP Update, as discussed in the preceding
paragraphs of this evaluation subsection; the inclusion of a safety
margin in the 2017 VOC motor vehicle emission budgets and whether the
area still achieves sufficient emissions reductions to demonstrate RFP
with such safety margin; \150\ and the comparison of the VOC emissions
reductions against the 15% ROP requirement. As shown in Table 6, the
RFP demonstration shows a 26.7% reduction in VOC emissions from 2011 to
2017 (i.e., 15% required reduction plus 11.7% surplus reduction). Such
reductions satisfy the ROP requirement for Imperial County for the 2008
ozone NAAQS.
---------------------------------------------------------------------------

    \150\ A safety margin is ``the amount by which the total
projected emissions from all sources of a given pollutant are less
than the total emissions that would satisfy the applicable
requirement for reasonable further progress, attainment, or
maintenance.'' 40 CFR 93.101. A safety margin allows future
transportation projects to increase on-road mobile source emissions
provided they satisfy applicable requirements (e.g., support a
demonstration of RFP in Imperial County in 2017) and the emissions
from such future projects are calculated using the same method.
---------------------------------------------------------------------------

    For these reasons, we propose to determine that the State has
demonstrated RFP in the applicable milestone year of 2017, consistent
with CAA requirements and EPA guidance. We therefore propose to approve
the RFP demonstrations under section 182(b)(1) of the CAA and 40 CFR
51.1110(a)(4)(i).

I. Motor Vehicle Emission Budgets

1. Statutory and Regulatory Requirements
    Section 176(c) of the CAA requires federal actions in nonattainment
and maintenance areas to conform to the SIP's goals of eliminating or
reducing the severity and number of violations of the NAAQS and
achieving timely attainment of the standards. Conformity to the SIP's
goals means that such actions will not: (1) Cause or contribute to
violations of a NAAQS, (2) worsen the severity of an existing
violation, or (3) delay timely attainment of any NAAQS or any interim
milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal
Transit Administration (FTA) funding or approval are subject to the
EPA's transportation conformity rule, codified at 40 CFR part 93,
subpart A. Under this rule, metropolitan planning organizations in
nonattainment and maintenance areas coordinate with state and local air
quality and transportation agencies, the EPA, the FHWA, and the FTA to
demonstrate that an area's regional transportation plans and
transportation improvement programs conform to the applicable SIP. This
demonstration is typically done by showing that estimated emissions
from existing and planned highway and transit systems are less than or
equal to the motor vehicle emission budgets (MVEBs or ``budgets'')
contained in all control strategy SIPs. Budgets are generally
established for specific years and specific pollutants or precursors.
Ozone plans should identify budgets for on-road emissions of ozone
precursors (NOX and VOC) in the area for each RFP milestone
year and the attainment year, if the plan demonstrates attainment.\151\
---------------------------------------------------------------------------

    \151\ 40 CFR 93.102(b)(2)(i).
---------------------------------------------------------------------------

    For budgets to be approvable, they must meet, at a minimum, the
EPA's adequacy criteria in 40 CFR 93.118(e)(4). To meet these
requirements, the budgets must be consistent with the attainment and
RFP requirements and reflect all the motor vehicle control measures
contained in the attainment and RFP demonstrations.\152\
---------------------------------------------------------------------------

    \152\ 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more
information on the transportation conformity requirements and
applicable policies on MVEBs, please visit our transportation
conformity website at: http://www.epa.gov/otaq/stateresources/transconf/index.htm.
---------------------------------------------------------------------------

    The EPA's process for determining adequacy of a budget consists of
three basic steps: (1) Providing public notification of a SIP
submission; (2) providing the public the opportunity to comment on the
budget during a public comment period; and, (3) making a finding of
adequacy or inadequacy.\153\
---------------------------------------------------------------------------

    \153\ 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------

2. Summary of State's Submission
    The Imperial Ozone Plan includes NOX and VOC budgets for
Imperial County for 2017 and states that they are consistent with the
emissions inventory used in the Plan's section 179B(a)
demonstration.\154\ The budgets were calculated by SCAG using updated
vehicle miles traveled estimates and speed distribution data in the
SCAG's 2016 RTP/SCS and updated emission rates and planning assumptions
from EMFAC2014.\155\ They reflect average summer weekday emissions
consistent with the 2017 RFP milestone year for the 2008 ozone NAAQS.
The 2017 on-road mobile source emissions are 6.53 tpd of NOX
and 3.13 tpd of VOC, and the 2017 budgets in the Imperial Ozone Plan
are 7 tpd of NOX and 4 tpd of VOC. In CARB's Technical
Clarification Letter, CARB identifies the difference between the 2017
on-road mobile source emissions and the 2017 budgets as a

safety margin of 0.4 tpd of NOX and 0.8 tpd of VOC.\156\
---------------------------------------------------------------------------

    \154\ Imperial Ozone Plan, 10-3. We note that the 2018 SIP
Update simply states that the 2017 budgets in the Imperial Ozone
Plan are still applicable. 2018 SIP Update, 13.
    \155\ At the time the Imperial Ozone Plan was developed,
EMFAC2014 was CARB's latest version of the EMFAC model for
estimating emissions from on-road vehicles operating in California
that had been approved into the California SIP. 80 FR 77337. It was
the appropriate model to use for SIP development purposes, as noted
in the EPA's implementation rule for the 2015 ozone NAAQS. 83 FR
62998, 63022, n. 54 (December 6, 2018).
    \156\ CARB's Technical Clarification Letter, Attachment A. We
note that the hundredths place of the 2017 emissions amounts are
rounded up to the nearest whole number (i.e., 6.53 tpd + 0.4 tpd =
6.93 tpd, rounded to 7 tpd NOX; and 3.13 tpd + 0.8 tpd =
3.93 tpd, rounded up to 4 tpd VOC).
---------------------------------------------------------------------------

    CARB also asked that the EPA limit the duration of the approval of
the 2017 budgets in the Imperial Ozone Plan and includes an explanation
for why the budgets have become, or will become, outdated or
deficient.\157\ In short, CARB has requested that we limit the duration
of the approval of the budgets in anticipation, in the near term, of
the EPA's approval of EMFAC2017, which is an updated version of the
model (EMFAC2014) used for the budgets in the Imperial Ozone Plan.\158\
EMFAC2017 updates vehicle mix and emissions data of the currently
approved version of the model, EMFAC2014.
---------------------------------------------------------------------------

    \157\ Letter dated December 5, 2018 from Richard Corey,
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA
Region IX, 2, and CARB's Technical Clarification Letter, 1-2.
    \158\ The EPA has approved EMFAC2017 for use in SIP development
and transportation conformity decisions in California. 84 FR 41717.
---------------------------------------------------------------------------

    CARB explains that, upon approval of EMFAC2017, the budgets from
the Imperial Ozone Plan, for which we are proposing approval in today's
action, will become outdated and will need to be revised using
EMFAC2017 within the grace period established in our approval of
EMFAC2017. This in turn would allow for the EPA to use the adequacy
process to review and replace the budgets proposed for approval in this
notice so that they can be used in future conformity determinations for
the SCAG regional transportation plan and program, as applied to
Imperial County. In addition, CARB states that, without the ability to
replace the budgets using the budget adequacy process, the benefits of
using the updated data may not be realized for a year or more after the
updated SIP (with the EMFAC2017-derived budgets) is submitted, due to
the length of the SIP approval process.
3. EPA Review of State's Submission
    We have evaluated the budgets in the Imperial Ozone Plan against
our adequacy criteria in 40 CFR 93.118(e)(4) as part of our review of
the budgets' approvability and will complete the adequacy review
concurrent with our final action on the ozone plan.\159\ The EPA is not
required under its transportation conformity rule to find budgets
adequate prior to proposing approval of them.\160\
---------------------------------------------------------------------------

    \159\ Memorandum from Karina O'Connor, Air Planning Office, EPA
Region IX, ``Adequacy Documentation for Plan Motor Vehicle Emission
Budgets in September 2017 Imperial Ozone Plan,'' May 24, 2019.
    \160\ Under the transportation conformity regulations, the EPA
may review the adequacy of submitted motor vehicle emission budgets
simultaneously with the EPA's approval or disapproval of the
submitted implementation plan. 40 CFR 93.118(f)(2).
    \161\ 40 CFR 93.118(e)(1).
    \162\ 67 FR 69141 (November 15, 2002), limiting our prior
approval of MVEB in certain California SIPs.
---------------------------------------------------------------------------

    As discussed in section II.H of this proposed rule, the 2011 RFP
baseline and 2017 RFP emissions inventories, including the figures for
mobile sources, were back-casted and forecasted, respectively, from the
2012 base year emissions inventory. For the reasons discussed in
section II.H of this proposed rule, we are proposing to approve the RFP
demonstration in the 2018 SIP Update, including the safety margins
identified in CARB's Technical Clarification Letter. While only the VOC
emissions reductions are required for ROP, the Imperial Ozone Plan's
demonstration of attainment but for emissions emanating from Mexico
relies on reductions of both NOX and VOC emissions. As
described in our summary of the State's submission, the 2017 budgets,
including safety margins, are shown in Table 7, below.

Table 7--2017 Motor Vehicle Emission Budgets for Imperial County for the
                            2008 Ozone NAAQS
------------------------------------------------------------------------
                                                     2017
                                     -----------------------------------
                                          NOX (tpd)         VOC (tpd)
------------------------------------------------------------------------
On-road Mobile Sources..............              6.53              3.13
Safety Margin.......................               0.4               0.8
Motor Vehicle Emission Budget                        7                 4
 (rounded to nearest whole number)..
------------------------------------------------------------------------
Source: 2018 SIP Update, Table II-2 and CARB's Technical Clarification
  Letter, Attachment A.

    The EPA has determined that these budgets are consistent with
emissions control measures in the SIP and RFP for the 2008 ozone NAAQS.
They are clearly identified and precisely quantified, and meet all
other applicable statutory and regulatory requirements, including the
adequacy criteria in 40 CFR 93.118(e)(4) and (5). In addition, we
conclude that CARB has identified an appropriate safety margin for the
2017 NOX and VOC MVEBs and demonstrated how such budgets
remain consistent with demonstrating RFP, as discussed in section II.F
of this proposed rule. For these reasons, the EPA is proposing to
approve the 2017 budgets in the Imperial Ozone Plan for transportation
conformity purposes for the 2008 ozone NAAQS. Also, we anticipate
completing the budget adequacy process upon our final rule.
    Under our transportation conformity rule, as a general matter, once
budgets are approved, they cannot be superseded by revised budgets
submitted for the same CAA purpose and the same period of years
addressed by the previously approved SIP until the EPA approves the
revised budgets as a SIP revision. In other words, as a general matter,
such approved budgets cannot be superseded by revised budgets found
adequate, but rather only through approval of the revised budgets,
unless the EPA specifies otherwise in its approval of a SIP by limiting
the duration of the approval to last only until subsequently submitted
budgets are found adequate.\161\
    In this instance, CARB has requested that we limit the duration of
our approval of the budgets in the Imperial Ozone Plan only until the
effective date of the EPA's adequacy finding for any subsequently
submitted budgets. Generally, we will consider a state's request to
limit an approval of an MVEB only if the request includes the following
elements: \162\
     An acknowledgement and explanation as to why the budgets
under consideration have become outdated or deficient;
     A commitment to update the budgets as part of a
comprehensive SIP update; and
     A request that the EPA limit the duration of its approval
to the time when new budgets have been found to be adequate for
transportation conformity purposes.
    We find that CARB's explanation for why the budgets will become
outdated

and why limiting the duration of the approval of the budgets is
appropriate. This information provides us with a reasonable basis on
which to limit the duration of the approval of the budgets.
    We note that CARB has not committed to update the budgets as part
of a comprehensive SIP update, but as a practical matter, CARB must
submit a SIP revision that includes updated demonstrations as well as
the updated budgets to meet the adequacy criteria in 40 CFR
93.118(e)(4); \163\ and thus, we do not need a specific commitment for
such a plan at this time. For the reasons provided above, and in light
of CARB's explanation for why the budgets will become outdated and
should be replaced upon an adequacy finding for updated budgets, we
propose to limit the duration of our approval of the budgets in the
Imperial Ozone Plan until new budgets have been found adequate.
---------------------------------------------------------------------------

    \163\ Under 40 CFR 93.118(e)(4), the EPA will not find a budget
in a submitted SIP to be adequate unless, among other criteria, the
budgets, when considered together with all other emissions sources,
are consistent with applicable requirements for RFP and attainment.
40 CFR 93.118(e)(4)(iv).
---------------------------------------------------------------------------

J. Contingency Measures

1. Statutory and Regulatory Requirements
    Under the CAA, ozone nonattainment areas classified under subpart 2
as Moderate must include in their SIPs contingency measures consistent
with section 172(c)(9).\164\ Contingency measures are additional
controls or measures to be implemented in the event the area fails to
meet RFP requirements or to attain the NAAQS by the attainment date.
The SIP should contain trigger mechanisms for the contingency measures,
specify a schedule for implementation of the measures, and indicate
that the measures will be implemented without significant further
action by the state or the EPA.\165\
---------------------------------------------------------------------------

    \164\ Contingency measures in ozone nonattainment areas
classified under CAA Title I, subpart 2 as Serious or higher must
also be consistent with CAA section 182(c)(9). However, this
requirement does not apply to the Imperial County nonattainment
area, which is classified as Moderate for the 2008 ozone NAAQS.
    \165\ 2008 Ozone SRR, 12285.
---------------------------------------------------------------------------

    Neither the CAA nor the EPA's implementing regulations establish a
specific amount of emissions reductions that implementation of
contingency measures must achieve, but the 2008 Ozone SRR reiterates
the EPA's recommendation that contingency measures should provide for
emissions reductions approximately equivalent to one year's worth of
RFP, thus amounting to reductions of 3% of the baseline emissions
inventory for the nonattainment area.\166\
---------------------------------------------------------------------------

    \166\ Id.
---------------------------------------------------------------------------

    It has been the EPA's longstanding interpretation of section
172(c)(9) that states may rely on existing federal measures (e.g.,
federal mobile source measures based on the incremental turnover of the
motor vehicle fleet each year) and state or local measures in the SIP
already scheduled for implementation that provide emissions reductions
in excess of those needed to meet any other nonattainment plan
requirements, such as meeting RACM/RACT, RFP, or expeditious attainment
requirements. The key is that the statute requires that contingency
measures provide for additional emissions reductions that are not
relied on for RFP or attainment and that are not included in the RFP or
attainment demonstrations as meeting part or all of the contingency
measure requirements. The purpose of contingency measures is to provide
continued emissions reductions while the state revises the SIP to meet
the missed milestone or attainment date.
    The EPA has approved numerous nonattainment area plan SIP
submissions under this interpretation, i.e., SIPs that use as
contingency measures one or more federal or state control measures that
are already in place and provide reductions that are in excess of the
reductions required to meet other requirements or relied upon in the
modeled attainment demonstration,\167\ and there is case law supporting
the EPA's interpretation in this regard.\168\ However, in Bahr v. EPA,
the Ninth Circuit rejected the EPA's interpretation of CAA section
172(c)(9) as allowing for approval of already implemented control
measures as contingency measures.\169\ The Ninth Circuit concluded that
contingency measures must be measures that would take effect at the
time the area fails to make RFP or to attain by the applicable
attainment date, not before.\170\ Thus, within the geographic
jurisdiction of the Ninth Circuit, states cannot rely on already
implemented control measures to comply with the contingency measure
requirements under CAA section 172(c)(9).
---------------------------------------------------------------------------

    \167\ E.g., 62 FR 15844 (April 3, 1997) (direct final rule
approving an Indiana ozone SIP revision); 62 FR 66279 (December 18,
1997) (final rule approving an Illinois ozone SIP revision); 66 FR
30811 (June 8, 2001) (direct final rule approving a Rhode Island
ozone SIP revision); 66 FR 586 (January 3, 2001) (final rule
approving District of Columbia, Maryland, and Virginia ozone SIP
revisions); and 66 FR 634 (January 3, 2001) (final rule approving a
Connecticut ozone SIP revision).
    \168\ E.g., LEAN v. EPA, 382 F.3d 575 (5th Cir. 2004) (upholding
contingency measures that were previously required and implemented
where they were in excess of the attainment demonstration and RFP
SIP).
    \169\ Bahr v. EPA, 836 F.3d 1218, 1235-1237 (9th Cir. 2016).
    \170\ Id.
---------------------------------------------------------------------------

2. Summary of State's Submission
    Imperial County APCD and CARB adopted the Imperial Ozone Plan after
the Bahr v. EPA decision. Nevertheless, the Plan relies upon surplus
emissions reductions from already implemented control measures in the
2017 RFP year to demonstrate compliance with the RFP contingency
measure requirements of CAA sections 172(c)(9).\171\ With respect to
the attainment contingency measure requirements, the Imperial Ozone
Plan stated that such measures are not required.\172\
---------------------------------------------------------------------------

    \171\ Imperial Ozone Plan, 5-1 to 5-2.
    \172\ Imperial Ozone Plan, Table 11-1.
---------------------------------------------------------------------------

    In the 2018 SIP Update, CARB revised the RFP demonstration for the
2008 ozone standards for Imperial County. Based on that demonstration
and the fact that 2017 had passed, CARB concludes that Imperial County
successfully met applicable RFP requirements in 2017 and, therefore,
the RFP contingency measure requirement in CAA section 172(c)(9) is
irrelevant for Imperial County for the 2008 ozone NAAQS.\173\
---------------------------------------------------------------------------

    \173\ Imperial Ozone Plan, 13.
---------------------------------------------------------------------------

3. EPA Review of State's Submission
    The EPA has reviewed the Imperial Ozone Plan and the 2018 SIP
Update and proposes that the contingency measure requirement of CAA
section 172(c)(9) for RFP is moot, as described below. Regarding the
contingency measure requirement of section 172(c)(9) for failure to
attain by the applicable attainment date, we propose that such measures
would no longer be required if the EPA were to finalize our proposed
approval of the section 179B demonstrations for Imperial County for the
2008 ozone NAAQS, as also described below.
    The contingency measure portion of the Imperial Ozone Plan, based
on the Plan's RFP demonstration from a 2008 RFP baseline emission
inventory through the 2017 RFP emission inventory, relies upon
emissions reductions that are surplus to those needed to demonstrate
RFP. As noted in our summary of the statutory and regulatory
requirements for contingency measures, states in the Ninth Circuit
cannot rely on already implemented control measures to comply with the
contingency measure requirements under CAA sections 172(c)(9), and thus
we do not propose to approve such an

approach for Imperial County for the 2008 ozone NAAQS.
    However, as described in section II.H of this proposed rule, we
reviewed the revised 2017 RFP emissions inventory and RFP demonstration
for Imperial County in the 2018 SIP Update. Given that the revised RFP
demonstration is based upon actual emissions reported for 2017 for
stationary point sources, and forecasted emissions for other sources
using updated activity data, consistent with the Imperial Ozone Plan's
section 179B(a) demonstration, using the appropriate metric (summer
emissions of ozone precursor pollutants) and that the area achieved
greater than 3% annual emissions reductions in VOC, we agree with CARB
that Imperial County has met applicable RFP requirements for 2017.
Because the area met RFP for 2017, and because no RFP demonstration is
required for a year beyond 2017 for Imperial County for the 2008 ozone
NAAQS, the event that would otherwise trigger implementation of RFP
contingency measures did not occur and will not occur in the future.
Accordingly, we propose that the RFP contingency measure requirement is
moot as applied to Imperial County for purposes of the 2008 ozone
NAAQS.
    With respect to attainment contingency measures, CARB and Imperial
County APCD state that attainment contingency measures are not required
due to the area's attainment but for the impacts of international
emissions. We agree that such measures are not required for Imperial
County for the 2008 ozone NAAQS as follows.
    Attainment contingency measures under CAA section 172(c)(9) are
triggered upon the EPA's determination that an area failed to attain a
given NAAQS by its applicable attainment date. However, section 179B(b)
provides that where a state demonstrates to the EPA that the area would
have attained the ozone NAAQS by the applicable attainment date but for
emissions emanating from outside the U.S., the area is not subject to
the reclassification provisions in section 181(b)(2) and will not be
reclassified to a higher nonattainment level.\174\ It is therefore
consistent with section 179B(b) to conclude that the EPA's approval of
a demonstration of attainment but for international emissions under
section 179B(b) means that the EPA is not required to make
determinations of attainment by the attainment date for that area.
Therefore, contingency measures would not be triggered for the area's
failure to attain by the attainment date, provided that the EPA has
approved the area's demonstration that it would have attained by the
applicable attainment date but for emissions emanating from outside the
U.S. Given these considerations, the EPA interprets the CAA not to
require contingency measures for failure to attain in an area with an
approved section 179B demonstration.
---------------------------------------------------------------------------

    \174\ The EPA's long held view is that CAA section 179B(b)'s
reference to section 181(a)(2) was made in error, and that Congress
actually intended to refer to section 181(b)(2). 83 FR 62998, 63009,
n.24; ``State Implementation Plans; General Preamble for the
Implementation of Title I of the Clean Air Act Amendments of 1990,''
57 FR 13498, 13569 n.41 (April 16, 1992).
---------------------------------------------------------------------------

    As described in sections II.G and III of this proposed rule, the
EPA proposes to approve the Imperial Ozone Plan, the 2018 SIP Update
(with respect to Imperial County), and the Imperial Ozone Retrospective
Demonstration under section 179B(b) that Imperial County would have
attained the 2008 ozone NAAQS by July 20, 2018, but for emissions from
Mexico. Thus, if the EPA were to finalize this proposed action, there
would be no requirement for the EPA to determine whether the area
attained the NAAQS, and therefore no requirement for the state to
submit attainment contingency measures. Accordingly, we propose that
the attainment contingency measure requirement does not apply to
Imperial County for the 2008 ozone NAAQS.

K. Other Requirements

    The Imperial Ozone Plan notes that the Moderate area requirements
of CAA section 182(b)(3) (``Gasoline vapor recovery'') no longer apply
since the promulgation of the Onboard Refueling Vapor Recovery Rule,
and that the requirements of section 182(b)(4) (``Motor vehicle
inspection and maintenance'') do not apply to Imperial County because
its population is below the 200,000 persons threshold.\175\ The EPA
agrees with CARB's assessment and proposes that these two requirements
do not apply in Imperial County for the 2008 ozone NAAQS.
---------------------------------------------------------------------------

    \175\ Imperial Ozone Plan, 1-1, n. 4. See also, 59 FR 16262
(April 6, 1994) (known as the Onboard Refueling Vapor Recovery Rule)
and 40 CFR 51.350(a)(8) (population threshold for applicability of
motor vehicle inspection and maintenance requirements).
---------------------------------------------------------------------------

III. Imperial County Ozone Determination of Attainment but for
International Emissions

A. Statutory and Regulatory Requirements

    Section 181(b)(2)(A) of the CAA requires that within 6 months
following the applicable attainment date, the EPA Administrator shall
determine whether an ozone nonattainment area attained the ozone
standards based on the area's design value as of that date.\176\ In the
event an area fails to attain the relevant ozone NAAQS by the
applicable attainment date, CAA section 181(b)(2)(A) requires the
Administrator to make the determination that the area failed to attain
the ozone standards and requires the area to be reclassified by
operation of law to the higher of (i) the next higher classification
for the area, or (ii) the classification applicable to the area's
design value as of the determination of failure to attain.
---------------------------------------------------------------------------

    \176\ We note that CAA section 181(a)(5) gives the Administrator
the discretion to grant a 1-year extension of the attainment date
specified in CAA section 181(a) upon application by any state if
certain criteria are met. However, CARB is not seeking such an
extension for Imperial County but rather invokes the provisions of
section 179B(b).
---------------------------------------------------------------------------

    Section 179B(b), however, provides that if a state demonstrates to
the EPA that an area would have attained the ozone NAAQS by the
applicable attainment date, but for emissions emanating from outside
the U.S., the area is not subject to the reclassification provisions in
section 181(b)(2) and will not be reclassified to a higher
nonattainment level. The EPA interprets section 179B(b) to involve an
analysis of the relationship between past exceedances (i.e., those used
in determining attainment) and international emissions.

B. Summary of State's Submission

    CARB submitted the Imperial Ozone Retrospective Demonstration to
the EPA on July 3, 2018.\177\ CARB states that despite air quality
improvement in Imperial County due to wide-ranging controls on
NOX and VOC sources, the area would not attain the 2008
ozone NAAQS by the July 20, 2018 attainment deadline.\178\ In the
Imperial Ozone Retrospective Demonstration, CARB presents an analysis
that estimated the ozone levels in Imperial County, without the
influence of emissions in the Mexicali Region, for 2017. The Imperial
Ozone Retrospective Demonstration is based on a number of factors,
including two modeling exercises: (1) Photochemical modeling in the
Imperial Ozone Plan, discussed in section II.G of this proposed rule;
and (2) the EPA's interstate air pollution transport modeling for the
2008 ozone NAAQS, including the CSAPR Update modeling results for 2017
and supplemental modeling results for

2023.\179\ CARB also presented a back trajectory analysis for each day
in 2015, 2016, and 2017 when the ozone level was above 75 ppb at any of
the three monitoring sites. CARB presented additional supporting
information, including a comparison of the emissions inventory for
ozone precursors in Imperial County to the emissions inventory to the
Mexicali Municipality, the ozone design value trends from 1996 to 2017,
and a discussion of the conditions that influence ozone formation in
Imperial County.
---------------------------------------------------------------------------

    \177\ Letter dated July 3, 2018, from Richard Corey, Executive
Officer, CARB, to Michael Stoker, Regional Administrator, EPA Region
9.
    \178\ Imperial Ozone Retrospective Demonstration, 1.
    \179\ 81 FR 74504; CSAPR Update Air Quality Modeling TSD; and
CSAPR Update 2008 Ozone Design Values and Contributions Spreadsheet;
and Supplemental 2008 Ozone Transport Memo.
---------------------------------------------------------------------------

1. Imperial Ozone Plan Attainment Demonstration Modeling
    To show the effect of emissions emanating from Northern Mexico on
ozone levels in Imperial County in 2017, CARB relied in part on
modeling conducted for the attainment demonstration in the Imperial
Ozone Plan. Specifically, CARB performed an exercise using existing
modeling results to estimate the effect of Mexican emissions within the
Southern California Modeling domain (i.e., a subset of the Mexican
emissions sources nearest Imperial County) and applied those estimates
to 2015-2017 design values.
    As discussed in section II.G of this proposed rule, the attainment
demonstration for the Imperial Ozone Plan includes two modeling
scenarios (or cases) for the year 2017. Case one was a ``base'' run
that used projected 2017 anthropogenic emissions for both the U.S. and
Mexicali Municipality within the modeling domain, while all other model
inputs were based on the year 2012. Case two was a ``sensitivity'' run,
where the only difference from the base run was that Mexican
anthropogenic emissions (within the modeling domain) were zeroed out.
The sensitivity run analysis estimated the ozone contribution from
Mexican emissions to Imperial County monitoring sites based on the
change in the predicted design values due to the removal of the Mexican
anthropogenic emissions (within the modeling domain). CARB then applied
the estimated ozone reduction from the removal of the Mexican emissions
as generated by the sensitivity run analysis to the measured 2015-2017
design value at each of the monitoring sites. The results are shown
here in Table 8.

         Table 8--CARB's 2015-2017 Design Values Estimates Based on Scaling Exercise From CARB Modeling
----------------------------------------------------------------------------------------------------------------
                                                                               Estimated 2015-
                                                                                2017 design
                                                             Measured 2015-     value without   Change in design
                      Monitoring site                          2017 design      anthropogenic    value (percent)
                                                               value (ppb)         Mexican
                                                                               emissions (ppb)
----------------------------------------------------------------------------------------------------------------
Niland....................................................                63              60.7               3.7
El Centro.................................................                76              65.9              13.3
Calexico..................................................                77              64.3              16.5
----------------------------------------------------------------------------------------------------------------
Source: Imperial Ozone Retrospective Demonstration, Table 2.

2. CARB's Estimate of Ozone Transport Based on the EPA's Air Quality
Modeling
    As part of the CSAPR Update rule, the EPA conducted air quality
modeling to project ozone concentrations at individual monitoring sites
in 2017 and to estimate state-by-state contributions to those 2017
concentrations.\180\ The EPA used the Comprehensive Air Quality Model
with Extensions (CAMx),\181\ including state-level ozone source
apportionment modeling using the OSAT/APCA technique.\182\ This
exercise involved tracking the ozone contribution at each receptor from
different sources (e.g., individual states, Mexico and Canada), as well
as boundary conditions. As noted in section II.G.3 of this proposed
rule, the EPA has released two sets of modeling results, one for year
2017 and one for year 2023.\183\ Both cases were simulated using a 2011
base year modeling platform, which means the 2011 meteorology and
boundary conditions were applied to both future year cases (2017 and
2023).
---------------------------------------------------------------------------

    \180\ 81 FR 74504; Air Quality Modeling Technical Support
Document for the Final Cross State Air Pollution Update (CSAPR
Update AQM TSD); and CSAPR Update 2008 Ozone Design Values and
Contributions Spreadsheet; and Supplemental 2008 Ozone Transport
Memo.
    \181\ For the final CSAPR Update rule, the EPA used CAMx version
6.20 (Ramboll Environ, 2015), which was the latest public release
version of CAMx available at the time the air quality modeling was
performed. CSAPR Update AQM TSD, 2, n.5.
    \182\ Id. at 15.
    \183\ Results for 2017 are available at: https://www.epa.gov/sites/production/files/2017-05/documents/aq_modeling_tsd_final_csapr_update.pdf. Results for are 2023
available at: https://www.epa.gov/airmarkets/october-2017-memo-and-supplemental-information-interstate-transport-sips-2008-ozone-naaqs.
---------------------------------------------------------------------------

    CARB's Imperial Ozone Retrospective Demonstration lists the
measured 8-hour ozone design value for 2015-2017 at each Imperial
County site.\184\ It also lists the estimated contribution to ozone in
Imperial County resulting from Mexican anthropogenic emissions based on
the CSAPR Update 2017.\185\ The Mexican contributions to the design
values at the Niland, El Centro, and Calexico sites are estimated to be
11%, 15%, and 17% respectively.\186\ Then, CARB estimated the 2015-2017
design values without the influence Mexican emissions for each site by
reducing the measured ozone design value by the percentage estimated by
the interstate transport modeling developed as part of the CSAPR Update
for that site. The results are shown in Table 9.
---------------------------------------------------------------------------

    \184\ Imperial Ozone Retrospective Demonstration, Table 4.
    \185\ The Canadian influence is assumed to be negligible.
    \186\ Imperial Ozone Retrospective Demonstration, Table 3. Due
to a major update of the Mexican emission inventory used in the 2023
modeling, the modeling results show higher ozone contributions from
Mexico at all Imperial County sites in 2023. This larger
contribution is likely due to an increase in Mexican emissions with
the update to the inventory, as well as a reduction in local
Imperial County emissions between 2017 and 2023.

            Table 9--CARB's 2017 Design Value Estimates Based on Scaling EPA's CSAPR Update Modeling
----------------------------------------------------------------------------------------------------------------
                                                                               Estimated 2015-
                                                                                2017 design
                                                             Measured 2015-     value without   Change in design
                      Monitoring site                          2017 design      anthropogenic    value (percent)
                                                               value (ppb)    Mexican emission
                                                                               inventory (ppb)
----------------------------------------------------------------------------------------------------------------
Niland....................................................                63              56.1              11.0
El Centro.................................................                76              64.4              15.3
Calexico..................................................                77              63.7              17.3
----------------------------------------------------------------------------------------------------------------
Source: Imperial Ozone Retrospective Demonstration, Table 4.

3. CARB's Back Trajectory Model Analysis
    CARB provided a trajectory analysis for each day that exceeded the
ozone standards at the Calexico and El Centro monitoring sites for the
years 2015, 2016, and 2017. There were no days that exceeded the 2008
Ozone NAAQS at the Niland monitoring site in that period. CARB used the
NOAA HYSPLIT model for its back trajectory modeling and identified the
hours of each exceedance day with the maximum 8-hour average ozone
value. CARB then used the HYSPLIT model to draw an 8-hour back
trajectory for each of the 8 hours of data that contributed to the
maximum 8-hour ozone value where each line drawn represents the back
trajectory for one hour at the air quality monitor.\187\
---------------------------------------------------------------------------

    \187\ Id., App. A.
---------------------------------------------------------------------------

    CARB listed each site and each exceedance day for which at least 5
out of 8 of the eight-hour back trajectories originated from or went
through the Mexicali region of Mexico (``CARB's 5 of 8 Back Trajectory
Test'').\188\ CARB determined that for Calexico, 11 of the 14 days were
likely to have an influence from sources in the Mexicali region since
they each had 5 or more hours with back trajectories passed through the
Mexicali region. For El Centro, CARB determined that 8 of the 12 days
were likely influenced by sources in the Mexicali region. CARB then
excluded the 8-hour monitoring values for the days for which there was
a likely influence from Mexico (i.e., 11 days for Calexico and 8 days
for El Centro) and calculated new design values for each site. CARB
listed the maximum 8-hour average ozone values on all exceedance days
at each site, resulting in 2015-2017 design values of 73 ppb in both
cases, as shown here in Table 10.
---------------------------------------------------------------------------

    \188\ Id., Table 6.

 Table 10--CARB's Predicted 2015-2017 Design Values Excluding Days With Likely Mexican Influence Based on CARB's
                                           5 of 8 Back Trajectory Test
----------------------------------------------------------------------------------------------------------------
                                                       Calexico                            El Centro
                                         -----------------------------------------------------------------------
                                                                4th high                            4th high
                  Year                                      excluding Mexico                    excluding Mexico
                                           4th high (ppb)    influenced days   4th high (ppb)    influenced days
                                                                  (ppb)                               (ppb)
----------------------------------------------------------------------------------------------------------------
2015....................................                77                74                77                72
2016....................................                74                73                74                73
2017....................................                82                74                79                75
2015-2017 Design Value..................                77                73                76                73
----------------------------------------------------------------------------------------------------------------
Source: Imperial Ozone Retrospective Demonstration, Table 7.

4. CARB's Additional Supporting Information
    The comparison of the emissions inventory shows that the Mexicali
Municipality and the NOX emissions (summer planning
inventory) are 3.8 times greater than those of Imperial County, and the
ROG emissions are 3.1 times greater, as shown in Table 11.

                                   Table 11--CARB's 2012 Imperial County and Mexicali Municipality Emissions Inventory
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Imperial County                          Mexicali Municipality
                                                                 ---------------------------------------------------------------------------------------
                             Source                               NOX (tpd)   NOX (%)                         NOX (tpd)   NOX (%)
                                                                                ROG (tpd)   ROG (%)                         ROG (tpd)   ROG (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stationary......................................................          2          8          1          7         15         18         14         24
Area-wide.......................................................          1          3          9         44         10         12         27         46
On-Road Mobile..................................................         10         46          4         22         56         66         17         29
Other Mobile....................................................          9         43          5         27          4          4        0.4          1
                                                                 ---------------------------------------------------------------------------------------
    Total.......................................................         22        100         19        100         85        100         59        100
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Imperial Ozone Retrospective Demonstration, Table 1.\189\

    CARB also included a figure displaying the 8-hour ozone design
value trend, which shows a decrease from 0.112 ppm 1996 to 0.079 ppm in
2010, and fairly consistent values from 2010 to 2017, with a design
value of 0.077 ppm for 2015-2017.\190\
---------------------------------------------------------------------------

    \189\ See also Imperial Ozone Plan, Table 8-1. Mexicali
emissions based on the EPA's 2011 Version 6.3 Platform inventory.
The 2011 Version 6.3 Platform is based on the 2011 NEI version 2 and
includes projected future years of 2017, 2023, and 2028. The 2011
Version 6.3 Platform supported the CSAPR Update, a rule related to
interstate transport for the 2008 ozone NAAQS.
    \190\ Imperial Ozone Retrospective Demonstration, Figure 3, 5.
---------------------------------------------------------------------------

C. EPA Review of State's Submission

    The EPA has reviewed CARB's analyses and agrees that, despite CARB
and Imperial County APCD's measures to reduce NOX and VOC
emissions, the 8-hour ozone design values at each ozone monitoring site
in Imperial County would have been below the 2008 ozone NAAQS of 75 ppb
for the 2015-2017 design value period, but for emissions emanating from
Mexico. We include the EPA's 179B TSD for Imperial County Ozone, which
provides further information regarding our evaluation of the Imperial
Ozone Retrospective Demonstration, in the docket of this proposed rule.
    First, we reviewed CARB's analysis of the contribution to ozone
from Mexican emissions based on CARB's modeling for demonstrating
attainment as part of the Imperial Ozone Plan. This scaling exercise
first estimated the contribution of Mexican anthropogenic emissions to
ozone formation on the measured 2015-2017 ozone design values by
assuming that the contribution to the 2015-2017 observed design values
was the same proportion as the contribution to the projected 2017 year
in the attainment demonstration. The scaling exercise then subtracted
this estimated contribution to ozone formation of Mexican anthropogenic
emissions from the measured 2015-2017 ozone design values, which
resulted in an Imperial County maximum design value of 65 ppb.\191\
---------------------------------------------------------------------------

    \191\ Imperial Ozone Plan, Table 8-2.
---------------------------------------------------------------------------

    The EPA believes the modeling that served as a basis for estimating
the contribution was sound. As discussed in section II.G.3 of this
proposed rule, CARB and the District implemented the modeling
procedures, tests, and performance analyses consistent with the EPA's
Modeling Guidance, discussed that modeling in detail, and found that
the model performed well. Also, CARB modeled attainment of the 2008
ozone NAAQS but for emissions from Mexico by modeling the year 2017,
both with and without the anthropogenic emissions inventory from Mexico
(within the modeling domain); given the availability of data to perform
such analyses, this is a reasonable method of assessing the degree to
which Mexican emissions affect ozone concentrations in Imperial County,
together with other lines of evidence.
    Second, we reviewed CARB's estimation of the contribution to ozone
from Mexican emissions based on modeling results from the EPA's
interstate air pollution transport modeling developed to estimate ozone
design values in the Moderate area attainment year of 2017 for the 2008
ozone NAAQS. We note that this is a similar yet distinct analysis from
the analysis described in section II.G.3 of this proposed rule. This
scaling exercise on the actual 2015-2017 design values use EPA's CSAPR
Update modeling to remove the estimated effect of Mexican emissions and
resulted in a maximum design value of 64 ppb for Imperial County. The
EPA's CSAPR Update modeling considered multiple aspects of the
transport of ozone, including consideration of measured and modeled
ambient ozone concentrations; estimated NOX and VOC
emissions inventories for the continental U.S., Mexico, Canada, and
boundary conditions; application of state of the science modeling tools
for regional air pollution analysis and appropriate model validation;
existing and planned emissions control regimes; and meteorology. While
the EPA did not design that modeling specifically to assess the degree
to which Mexican emissions may affect ozone concentrations in Imperial
County, CARB's method of employing the CSAPR Update data among several
other lines of evidence is reasonable and estimates that the effect of
the Mexican emissions (11% to 17%) would be in a similar range as
CARB's analysis of its own modeling (3.7% to 16.5%).
    Thus, each of the two modeling exercises indicates that the
measured 2015-2017 design values with the predicted impact from Mexican
emissions removed would be below the 2008 ozone NAAQS for all three
monitoring sites. These analyses make use of detailed and appropriate
modeling techniques and data sets and support CARB's conclusion that
Imperial County would have attained the 2008 Ozone NAAQS by the 2017
attainment year but for emissions emanating from Mexico.
    Third, we reviewed CARB's back trajectory analyses, wherein CARB
studied each day that exceeded the 2008 ozone NAAQS at the Calexico and
El Centro monitoring sites for the years 2015, 2016, and 2017, and
determined which days at the Calexico and El Centro sites were likely
to have been influenced by sources in the Mexicali region. As a
complement to Table 10 of this proposed rule, we summarized the count
of exceedance days that were likely influenced by Mexican emissions
based on CARB's 5 of 8 Back Trajectory Test and the count of such days
likely to be influenced to a lesser degree by Mexican emissions (4 or
less of 8 back trajectories). These counts are shown in Table 12.

    Table 12--EPA's Count of Days Influenced by Mexican Emissions Based on CARB's 5 of 8 Back Trajectory Test
----------------------------------------------------------------------------------------------------------------
                                                       Calexico                            El Centro
                                         -----------------------------------------------------------------------
                                            Count of days                       Count of days
                  Year                       with likely      Count of days      with likely      Count of days
                                           influence from   with less likely   influence from   with less likely
                                           Mexico (5 of 8    influence from    Mexico (5 of 8    influence from
                                                Test)            Mexico             Test)            Mexico
----------------------------------------------------------------------------------------------------------------
2015....................................                 4                 0                 6                 0
2016....................................                 2                 1                 1                 1
2017....................................                 8                 2                 5                 3
----------------------------------------------------------------------------------------------------------------

    The EPA finds that CARB's methodology for assessing the potential
effect of Mexican emissions on recorded ozone exceedances in Imperial
County is a reasonable means, among several lines of evidence, for
identifying exceedance days and the highest 8-hour period within each
such day and examining the origin and pathway of air traveling each
hour to the Imperial County monitoring sites within that 8-hour period.
    In addition to reviewing the approach and results of CARB's 5 of 8
Back Trajectory Test, the EPA considered a more stringent test that
would only remove an exceedance day if 75% (6 of 8) of the back
trajectories originated in or passed through Mexico (``EPA's 6 of 8
Back Trajectory Test'') as this would reflect a more conservative
approach to examining how many days may have been affected by emissions
from sources in the Mexicali region.
    The EPA reanalyzed the data and determined that 8 of the 14 days
for Calexico and 5 of the 12 days for El Centro were likely to have an
influence from sources in the Mexicali region.\192\ As CARB had done,
the EPA excluded the days for which there was a likely influence from
Mexico (i.e., 8 days at Calexico and 5 days for El Centro) and
calculated new design values for each site. This more stringent
analysis resulted in an Imperial County design value of 75 ppb, as
shown here in Table 13, supporting the conclusion that Imperial County
would have attained the 2008 ozone NAAQS by the 2017 attainment year
but for emissions emanating from Mexico. This estimated design value is
higher than the estimated design value from the modeling exercises
discussed herein because many of the days with fewer than 6
trajectories emanating from Mexico are likely to have some contribution
from Mexico. This approach is also conservative because there is likely
Mexico influence on all days and this method only removes days where
the Mexico influence is expected to be largest.
---------------------------------------------------------------------------

    \192\ For the days identified for El Centro with trajectories as
having a likely influence from Mexico, the EPA has conducted
additional trajectory analyses to further assess the influence of
the Mexicali emissions. This information is provided in the EPA's
179B TSD for Imperial County Ozone.

 Table 13--EPA's Predicted 2015-2017 Design Values Excluding Days With Likely Mexican Influence Based on EPA's 6
                                            of 8 Back Trajectory Test
----------------------------------------------------------------------------------------------------------------
                                                       Calexico                            El Centro
                                         -----------------------------------------------------------------------
                                                                4th high                            4th high
                  Year                                          excluding                           excluding
                                           4th high (ppb)        Mexico        4th high (ppb)        Mexico
                                                             influenced days                     influenced days
                                                                  (ppb)                               (ppb)
----------------------------------------------------------------------------------------------------------------
2015....................................                77                74                77                73
2016....................................                74                74                74                73
2017....................................                82                75                79                79
2015-2017 Design Value..................                77                74                76                75
----------------------------------------------------------------------------------------------------------------

    For comparison, we also include a count of exceedance days that
were likely influenced by Mexican emissions based on EPA's 6 of 8 Back
Trajectory Test and the count of such days likely to be influenced to a
lesser degree by Mexican emissions (5 or less of 8 back trajectories).
These counts are shown in Table 14.

    Table 14--EPA's Count of Days Influenced by Mexican Emissions Based on EPA's 6 of 8 Back Trajectory Test
----------------------------------------------------------------------------------------------------------------
                                                       Calexico                            El Centro
                                         -----------------------------------------------------------------------
                                            Count of days                       Count of days
                  Year                       with likely      Count of days      with likely      Count of days
                                           influence  from  with less likely   influence  from  with less likely
                                           Mexico  (6 of 8   influence from    Mexico (6 of 8    influence from
                                                Test)            Mexico             Test)            Mexico
----------------------------------------------------------------------------------------------------------------
2015....................................           \193\ 4                 0                 4                 2
2016....................................                 0                 3                 1                 1
2017....................................                 7                 3                 0                 8
----------------------------------------------------------------------------------------------------------------

    The additional information provided by the State also supports the
conclusion that Imperial County would have attained the 2008 ozone
NAAQS by the attainment date of July 20, 2018, but for emissions
emanating from Mexico. In brief, the emission inventory data presented
indicate that the Mexicali Municipality emits three times the amount of
ozone precursors emitted in Imperial County, such emissions could have
had a substantial effect on Imperial County ozone concentrations, and
Imperial County ozone concentrations would have been lower in the
absence of Mexican emissions. In addition, the proximity of the Mexican
border to the monitoring sites (1 mile from Calexico and 9 miles from
El Centro) and the shared topography and meteorology of Imperial Valley
also support the potential of Mexican emissions having a substantial
and immediate effect on ozone concentrations in Imperial County.
---------------------------------------------------------------------------

    \193\ September 23, 2015 has 5 of the 6 trajectories (83%) for
which data was available originating in Mexico. Thus, we included
this exceedance day in the count of days with likely influence from
Mexico.
---------------------------------------------------------------------------

    In conclusion, the EPA evaluated the information provided by CARB
and applied a more conservative test using CARB's back trajectory
method. CARB's modeling estimates of Mexican contribution based on
modeling data from the Imperial Ozone Plan attainment demonstration and
the EPA's CSAPR Update modeling, and the EPA's application of a more
conservative test using CARB's back trajectory method to analyze
exceedance days in the 2015-2017 design value period together support
the conclusion that Imperial County would have attained the standards
but for the impacts of emissions from Mexico. Furthermore, the
emissions inventory, showing that the ozone precursor emissions for
Mexicali Municipality are over three times those emitted in Imperial
County, and the proximity and shared airshed of the Calexico and El
Centro monitor to these emissions, also support the conclusion that the
Mexican emissions affected the ozone concentrations at these sites.
    Thus, based on our evaluation of these several lines of evidence
and analyses that together support the same conclusion, the EPA
proposes to determine, under CAA sections 179B(b) and 181(b)(2)(A),
that Imperial County would have attained the 2008 ozone NAAQS by the
Moderate area attainment date of July 20, 2018, but for emissions
emanating from Mexico.

IV. Proposed Action

    For the reasons discussed in this notice, under CAA section
110(k)(3), the EPA is proposing to approve, as a revision to the
California SIP, the Imperial Ozone Plan and the Imperial County portion
of the 2018 SIP Update related to:
     Emissions statement certification as meeting the
requirements of CAA section 182(a)(3)(B);
     Base year emissions inventory as meeting the requirements
of CAA sections 172(c)(3) and 182(a)(1) and 40 CFR 51.1115 with respect
to attainment planning;
     RACM demonstration as meeting the requirements of CAA
section 172(c)(1) and 40 CFR 51.1112(c);
     RFP demonstration as meeting the requirements of CAA
section 182(b)(1) and 40 CFR 51.1110(a)(4)(i); and
     Motor vehicle emission budgets for the 2017 RFP milestone
year because they are consistent with the RFP demonstration and the
demonstration of attainment but for international emissions that are
proposed for approval herein and meet the other criteria in 40 CFR
93.118(e).
    We also propose that finalization of this action would render the
RFP contingency measure requirement of CAA section 172(c)(9) moot and
that attainment contingency measures would no longer be required, as
discussed in section II.J of this proposed rule.
    Given our proposal that the Imperial Ozone Plan meets all
requirements for the Imperial County Moderate ozone nonattainment area,
other than the requirement to demonstrate attainment, and our
evaluation of the State's lines of evidence that together support the
conclusion that Imperial County would attain the 2008 ozone NAAQS by
the July 20, 2018 attainment date but for emissions emanating from
Mexico, the EPA proposes to approve the Imperial Ozone Plan's section
179B attainment demonstration as meeting the requirements of CAA
sections 172(c)(1), 182(b)(1)(A), and 179B(a) and 40 CFR 51.1108.
    Concurrently, we are proposing to determine, consistent with our
evaluation of the Imperial Ozone Plan, the 2018 Update, and Imperial
Ozone Retrospective Demonstration, that the Imperial County
nonattainment area would have attained the 2008 ozone NAAQS by the
Moderate area attainment date of July 20, 2018, but for emissions
emanating from outside of the United States, under CAA sections
179B(b). Therefore, if finalized, the EPA's obligation under section
181(b)(2)(A) to determine whether the area attained by its attainment
date would no longer apply and the area would not be reclassified.
    The EPA is soliciting public comments on the issues discussed in
this document. We will accept comments from the public on this proposal
for the next 30 days and will consider comments before taking final
action.

V. Statutory and Executive Order Reviews

    With respect to our proposal on the Imperial Ozone Plan and the
2018 SIP Update, under the Clean Air Act, the Administrator is required
to approve a SIP submission that complies with the provisions of the
Act and applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR
52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to
approve state choices, provided that they meet the criteria of the
Clean Air Act. Accordingly, this proposed action merely proposes to
approve state plans

as meeting federal requirements and does not impose additional
requirements beyond those imposed by state law.
    With respect to our proposed determination that Imperial County
attained the 2008 ozone NAAQS by July 20, 2018 but for emissions from
Mexico, the purpose of this rule is to determine whether Imperial
County attained the 2008 ozone standards by its Moderate area
attainment date, which is required under the CAA for purposes of
implementing the 2008 ozone standards.
    For these reasons, this proposed action:
     Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Orders
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21,
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2,
2017) regulatory action because SIP approvals are exempted under
Executive Order 12866;
     Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
     Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act; and
     Does not provide the EPA with the discretionary authority
to address disproportionate human health or environmental effects with
practical, appropriate, and legally permissible methods under Executive
Order 12898 (59 FR 7629, February 16, 1994).
    In addition, with respect to our proposal on the Imperial Ozone
Plan and the 2018 SIP Update, the SIP is not approved to apply on any
Indian reservation land or in any other area where the EPA or an Indian
tribe has demonstrated that a tribe has jurisdiction. In those areas of
Indian country, the proposed rule does not have tribal implications and
will not impose substantial direct costs on tribal governments or
preempt tribal law as specified by Executive Order 13175 (65 FR 67249,
November 9, 2000).
    However, with respect to our proposed determination that Imperial
County attained the 2008 ozone NAAQS by July 20, 2018, but for
emissions from Mexico, this action has tribal implications.
Nonetheless, it will neither impose substantial direct compliance costs
on federally recognized tribal governments, nor preempt tribal law. Two
tribes have areas of Indian country within or directly adjacent to the
Imperial County: Quechan Tribe of the Fort Yuma Indian Reservation and
the Torres Martinez Desert Cahuilla Indians. The EPA intends to
communicate with potentially affected tribes located within or directly
adjacent to the boundaries of Imperial County on this proposed action.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide,
Incorporation by reference, Intergovernmental relations, Nitrogen
dioxide, Ozone, Particulate matter, Reporting and recordkeeping
requirements, Volatile organic compounds.

    Authority: 42 U.S.C. 7401 et seq.

    Dated: September 30, 2019.
 Deborah Jordan,
Acting Regional Administrator, Region IX.
[FR Doc. 2019-23134 Filed 10-31-19; 8:45 am]
BILLING CODE 6560-50-P


[Federal Register Volume 82, Number 108 (Wednesday, June 7, 2017)]
[Proposed Rules]
[Pages 26406-26407]
[FR Doc No: 2017-11395]

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 71

[Docket No. FAA-2016-9549; Airspace Docket No. 17-ASO-5]

Proposed Amendment of Class E Airspace, Alexander City, AL

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This action proposes to amend Class E airspace at Alexander
City, AL, due to the decommissioning of the Alexander City non-
directional beacon (NDB), which requires airspace reconfiguration at
Thomas C Russell Field Airport. Controlled airspace is necessary for
the safety and management of instrument flight rules (IFR) operations
at the airport. This action also would update the geographic
coordinates of the airport.

DATES: Comments must be received on or before July 24, 2017.

ADDRESSES: Send comments on this proposal to: U.S. Department of
Transportation, Docket Operations, 1200 New Jersey Avenue SE., West
Bldg Ground Floor Rm W12-140, Washington, DC 20590; Telephone: 1-(800)-
647-5527, or<PHONE_NUMBER>. You must identify the Docket No. FAA-2016-
9549; Airspace Docket No. 17-ASO-5, at the beginning of your comments.
You may also submit and review received comments through the Internet
at http://www.regulations.gov. You may review the public docket
containing the proposal, any comments received, and any final
disposition in person in the Dockets Office between 9:00 a.m. and 5:00
p.m., Monday through Friday, except federal holidays.
    FAA Order 7400.11A, Airspace Designations and Reporting Points, and
subsequent amendments can be viewed on line at http://www.faa.gov/air_traffic/publications/. For further information, you can contact the
Airspace Policy Group, Federal Aviation Administration, 800
Independence Avenue SW., Washington, DC 20591; telephone: (202) 267-
8783. The Order is also available for inspection at the National
Archives and Records Administration (NARA). For information on the
availability of FAA Order 7400.11A at NARA, call<PHONE_NUMBER>, or go
to http://www.archives.gov/federal_register/code_of_federal-regulations/ibr_locations.html.
    FAA Order 7400.11, Airspace Designations and Reporting Points, is
published yearly and effective on September 15.

FOR FURTHER INFORMATION CONTACT: John Fornito, Operations Support
Group, Eastern Service Center, Federal Aviation Administration, P.O.
Box 20636, Atlanta, Georgia 30320; telephone<PHONE_NUMBER>.

SUPPLEMENTARY INFORMATION:

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is
found in Title 49 of the United States Code. Subtitle I, Section 106
describes the authority of the FAA Administrator. Subtitle VII,
Aviation Programs, describes in more detail the scope of the agency's
authority. This rulemaking is promulgated under the authority described
in Subtitle VII, Part A, Subpart I, Section 40103. Under that section,
the FAA is charged with prescribing regulations to assign the use of
airspace necessary to ensure the safety of aircraft and the efficient
use of airspace. This regulation is within the scope of that authority
as it would amend Class E airspace at Thomas C Russell Field Airport,
Alexander City,

AL to ensure the safety and management of IFR operations at the
airport.

Comments Invited

    Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments, as they may desire.
Comments that provide the factual basis supporting the views and
suggestions presented are particularly helpful in developing reasoned
regulatory decisions on the proposal. Comments are specifically invited
on the overall regulatory, aeronautical, economic, environmental, and
energy-related aspects of the proposal.
    Communications should identify both docket numbers and be submitted
in triplicate to the address listed above. You may also submit comments
through the Internet at http://www.regulations.gov.
    Persons wishing the FAA to acknowledge receipt of their comments on
this action must submit with those comments a self-addressed stamped
postcard on which the following statement is made: ``Comments to Docket
No. FAA-2016-9549; Airspace Docket No. 17-ASO-5.'' The postcard will be
date/time stamped and returned to the commenter.
    All communications received before the specified closing date for
comments will be considered before taking action on the proposed rule.
The proposal contained in this notice may be changed in light of the
comments received. A report summarizing each substantive public contact
with FAA personnel concerned with this rulemaking will be filed in the
docket.

Availability of NPRMs

    An electronic copy of this document may be downloaded through the
internet at http://www.regulations.gov. Recently published rulemaking
documents can also be accessed through the FAA's Web page at http://www.faa.gov/air_traffic/publications/airspace_amendments/.
    You may review the public docket containing the proposal, any
comments received, and any final disposition in person in the Dockets
Office (see the ADDRESSES section for address and phone number) between
9:00 a.m. and 5:00 p.m., Monday through Friday, except federal
holidays. An informal docket may also be examined between 8:00 a.m. and
4:30 p.m., Monday through Friday, except federal holidays at the office
of the Eastern Service Center, Federal Aviation Administration, Room
350, 1701 Columbia Avenue, College Park, GA 30337.

Availability and Summary of Documents for Incorporation by Reference

    This document proposes to amend FAA Order 7400.11A, Airspace
Designations and Reporting Points, dated August 3, 2016, and effective
September 15, 2016. FAA Order 7400.11A is publicly available as listed
in the ADDRESSES section of this document. FAA Order 7400.11A lists
Class A, B, C, D, and E airspace areas, air traffic service routes, and
reporting points.

The Proposal

    The FAA is considering an amendment to Title 14, Code of Federal
Regulations (14 CFR) part 71 to amend Class E airspace extending upward
from 700 feet or more above the surface within a 7.7-mile radius of
Thomas C Russell Field Airport, Alexander City, AL. The segment
extending from the 7.7-mile radius of the airport to 7 miles south of
the Alexander City NDB would be removed due to the decommissioning of
the Alexander City NDB and cancellation of the NDB approach, and for
continued safety and management of IFR operations at the airport. The
geographic coordinates of the airport also would be adjusted to
coincide with the FAAs aeronautical database.
    Class E airspace designations are published in Paragraph 6005 of
FAA Order 7400.11A, dated August 3, 2016, and effective September 15,
2016, which is incorporated by reference in 14 CFR 71.1. The Class E
airspace designation listed in this document will be published
subsequently in the Order.

Regulatory Notices and Analyses

    The FAA has determined that this proposed regulation only involves
an established body of technical regulations for which frequent and
routine amendments are necessary to keep them operationally current.
It, therefore: (1) Is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under DOT
Regulatory Policies and Procedures (44 FR 11034; February 26, 1979);
and (3) does not warrant preparation of a Regulatory Evaluation as the
anticipated impact is so minimal. Since this is a routine matter that
will only affect air traffic procedures and air navigation, it is
certified that this proposed rule, when promulgated, will not have a
significant economic impact on a substantial number of small entities
under the criteria of the Regulatory Flexibility Act.

Environmental Review

    This proposal will be subject to an environmental analysis in
accordance with FAA Order 1050.1F, ``Environmental Impacts: Policies
and Procedures'' prior to any FAA final regulatory action.

Lists of Subjects in 14 CFR Part 71

    Airspace, Incorporation by reference, Navigation (air).

The Proposed Amendment

    In consideration of the foregoing, the Federal Aviation
Administration proposes to amend 14 CFR part 71 as follows:

PART 71--DESIGNATION OF CLASS A, B, C, D, AND E AIRSPACE AREAS; AIR
TRAFFIC SERVICE ROUTES; AND REPORTING POINTS

0
1. The authority citation for part 71 continues to read as follows:

    Authority: 49 U.S.C. 106(f), 106(g); 40103, 40113, 40120; E.O.
10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389.

Sec.  71.1  [Amended]

0
2. The incorporation by reference in 14 CFR 71.1 of Federal Aviation
Administration Order 7400.11A, Airspace Designations and Reporting
Points, dated August 3, 2016, and effective September 15, 2016, is
amended as follows:

Paragraph 6005 Class E Airspace Areas Extending Upward From 700
Feet or More Above the Surface of the Earth.

* * * * *

ASO AL E5 Alexander City, AL [Amended]

Thomas C. Russell Field Airport, AL
    (Lat. 32[deg]54'53'' N., long. 85[deg]57'47'' W.)

    That airspace extending upward from 700 feet above the surface
within a 7.7-mile radius of Thomas C. Russell Field Airport.

    Issued in College Park, Georgia, on May 19, 2017.
Ryan W. Almasy,
Manager, Operations Support Group, Eastern Service Center, Air Traffic
Organization.
[FR Doc. 2017-11395 Filed 6-6-17; 8:45 am]
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