Document ID: EPA-R09-OAR-2020-0254-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: West Mojave Desert, CA; 2008 8-Hour Ozone Nonattainment Area Requirements
Posted Date: 2021-05-10T04:00Z

[Federal Register Volume 86, Number 88 (Monday, May 10, 2021)]
[Proposed Rules]
[Pages 24809-24829]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-09842]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2020-0254; FRL-10023-52-Region 9]

Clean Air Plans; 2008 8-Hour Ozone Nonattainment Area 
Requirements; West Mojave Desert, California

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve, or conditionally approve, all or portions of the state 
implementation plan (SIP) revision submitted by the State of California 
to meet Clean Air Act requirements for the 2008 8-hour ozone national 
ambient air quality standards (NAAQS or ``standards'') in the West 
Mojave Desert ozone nonattainment area. The SIP revision addresses the 
nonattainment area requirements for the

[[Page 24810]]

2008 8-hour ozone NAAQS, including the requirements for an emissions 
inventory, emissions statements, attainment demonstration, reasonable 
further progress, reasonably available control measures, contingency 
measures, and motor vehicle emissions budgets. The EPA is proposing to 
approve the SIP revision as meeting all the applicable ozone 
nonattainment area requirements, except for contingency measures, for 
which we are proposing conditional approval.

DATES: Written comments must arrive on or before June 9, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2020-0254 at https://www.regulations.gov. For comments submitted at 
Regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. The EPA may publish any comment received to its public 
docket. Do not submit electronically any information you consider to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Multimedia submissions (audio, 
video, etc.) must be accompanied by a written comment. The written 
comment is considered the official comment and should include 
discussion of all points you wish to make. The EPA will generally not 
consider comments or comment contents located outside of the primary 
submission (i.e., on the web, cloud, or other file sharing system). For 
additional submission methods, please contact the person identified in 
the FOR FURTHER INFORMATION CONTACT section. For the full EPA public 
comment policy, information about CBI or multimedia submissions, and 
general guidance on making effective comments, please visit http://www.epa.gov/dockets/commenting-epa-dockets. If you need assistance in a 
language other than English or if you are a person with disabilities 
who needs a reasonable accommodation at no cost to you, please contact 
the person identified in the FOR FURTHER INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: Tom Kelly, EPA Region IX, (415) 972-
3856, kelly.thomasp@epa.gov.

SUPPLEMENTARY INFORMATION:  Throughout this document, ``we,'' ``us,'' 
and ``our'' refer to the EPA.

Table of Contents

I. Regulatory Context
    A. Ozone Standards, Area Designations, and SIPs
    B. The West Mojave Desert Ozone Nonattainment Area
    C. CAA and Regulatory Requirements for 2008 Ozone Nonattainment 
Area SIPs
II. Submissions From the State of California To Address 2008 Ozone 
Standards Requirements in the West Mojave Desert
    A. Summary of Submissions
    B. Clean Air Act Procedural Requirements for Adoption and 
Submission of SIP Revisions
III. Evaluation of the 2016 WMD Attainment Plan and the 2018 SIP 
Update
    A. Emissions Inventories
    B. Emissions Statements
    C. Reasonably Available Control Measures Demonstration
    D. Attainment Demonstration
    E. Rate of Progress Plan and Reasonable Further Progress 
Demonstration
    F. Transportation Control Strategies and Measures To Offset 
Emissions Increases From Vehicle Miles Traveled
    G. Contingency Measures
    H. Motor Vehicle Emissions Budgets for Transportation Conformity
    I. Other Clean Air Act Requirements Applicable to Severe Ozone 
Nonattainment Areas
IV. Proposed Action
V. Statutory and Executive Order Reviews

I. Regulatory Context

A. Ozone Standards, Area Designations, and SIPs

    Ground-level ozone pollution is formed from the reaction of 
volatile organic compounds (VOC) and oxides of nitrogen 
(NOX) in the presence of sunlight.\1\ These two pollutants, 
referred to as ozone precursors, are emitted by many types of sources, 
including on-and off-road motor vehicles and engines, power plants and 
industrial facilities, and smaller area sources such as lawn and garden 
equipment and paints.
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    \1\ The State of California typically refers to reactive organic 
gases (ROG) in its ozone-related submissions since VOC in general 
can include both reactive and unreactive gases. However, since ROG 
and VOC inventories pertain to common chemical species (e.g., 
benzene, xylene, etc.), we refer to this set of gases as VOC in this 
proposed rule.
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    Scientific evidence indicates that adverse public health effects 
occur following exposure to ozone, particularly in children and adults 
with lung disease. Breathing air containing ozone can reduce lung 
function and inflame airways, which can increase respiratory symptoms 
and aggravate asthma or other lung diseases.\2\
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    \2\ See ``Fact Sheet--2008 Final Revisions to the National 
Ambient Air Quality Standards for Ozone'' dated March 2008.
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    Under section 109 of the Clean Air Act (CAA or ``Act''), the EPA 
promulgates NAAQS for pervasive air pollutants, such as ozone. The EPA 
has previously promulgated NAAQS for ozone in 1979 and 1997.\3\ In 
2008, the EPA revised and further strengthened the ozone NAAQS by 
setting the acceptable level of ozone in the ambient air at 0.075 parts 
per million (ppm) averaged over an 8-hour period.\4\ Although the EPA 
further tightened the 8-hour ozone NAAQS to 0.070 ppm in 2015, this 
action relates to the requirements for the 2008 ozone NAAQS.\5\
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    \3\ The ozone NAAQS promulgated in 1979 was 0.12 parts per 
million (ppm) averaged over a 1-hour period. See 44 FR 8202 
(February 8, 1979). The ozone NAAQS promulgated in 1997 was 0.08 ppm 
averaged over an 8-hour period. See 62 FR 38856 (July 18, 1997).
    \4\ 73 FR 16436 (March 27, 2008).
    \5\ Information on the 2015 ozone NAAQS is available at 80 FR 
65292 (October 26, 2015).
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    Following promulgation of a new or revised NAAQS, the EPA is 
required under CAA section 107(d) to designate areas throughout the 
country as attaining or not attaining the NAAQS. The ``Los Angeles-San 
Bernardino Counties (West Mojave Desert), CA'' area (``West Mojave 
Desert'' or WMD) was designated as nonattainment for the 2008 ozone 
standards on May 21, 2012 and classified as ``Severe-15.'' \6\
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    \6\ 77 FR 30088 (May 21, 2012).
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    Under the CAA, after the EPA designates areas as nonattainment for 
a NAAQS, states with nonattainment areas are required to submit SIP 
revisions that provide for, among other things, attainment of the NAAQS 
within certain prescribed periods that vary depending on the severity 
of nonattainment. Areas classified as Severe-15 must attain the NAAQS 
within 15 years of the effective date of the nonattainment 
designation.\7\
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    \7\ CAA section 181(a)(1), 40 CFR 51.1102 and 51.1103(a).
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    In California, the California Air Resources Board (CARB) is the 
agency responsible for the adoption and submission to the EPA of 
California SIPs and SIP revisions, and it has broad authority to 
establish emissions standards and other requirements for mobile 
sources. Local and regional air pollution control districts in 
California are responsible for the regulation of stationary sources and 
are generally responsible for the development of regional air quality 
plans. In the West Mojave Desert, two agencies develop and adopt air 
quality management plans to address CAA planning requirements 
applicable to that region, the Antelope Valley Air Quality Management 
District (AVAQMD) and the Mojave Desert Air Quality Management District 
(MDAQMD) (collectively, ``Districts''). Such plans are then submitted 
to CARB for adoption and submittal to the EPA as revisions to the 
California SIP.

[[Page 24811]]

B. The West Mojave Desert Ozone Nonattainment Area

    The West Mojave Desert is located in northeast Los Angeles County 
and southwest San Bernardino County. For a precise description of the 
geographic boundaries of the area, see 40 CFR 81.305. The Los Angeles 
County portion of the WMD area is under the jurisdiction of the AVAQMD, 
and the San Bernardino County portion of the area is under the 
jurisdiction of the MDAQMD.
    The population of the West Mojave Desert is approximately 
868,380.\8\ Ambient 8-hour ozone concentrations in the WMD are above 
the level of the 2008 8-hour ozone NAAQS. The area's maximum design 
value for the 2017-2019 period, based on certified data at the Phalen 
monitor (Air Quality System ID: 06-071-0012), is 0.096 ppm.\9\
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    \8\ 8-Hour Ozone (2008) Designated Area/State Information, Green 
Book, EPA, accessed on November 19, 2020, Population Data from 2010, 
https://www3.epa.gov/airquality/greenbook/hbtc.html.
    \9\ Air Quality System (AQS) Design Value Report, 
O3_designvalues_2017_2019_final_5_26_20.pdf, in the docket for this 
proposed action. The AQS is a database containing ambient air 
pollution data collected by the EPA and state, local, and tribal air 
pollution control agencies from over thousands of monitors. Design 
values, defined to be consistent with the individual NAAQS as 
described in 40 CFR part 50, are typically used to designate and 
classify nonattainment areas, as well as to assess progress towards 
meeting the NAAQS.
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    The West Mojave Desert receives significant transport of ozone and 
ozone precursors from the South Coast Air Basin, and to a lesser 
extent, the San Joaquin Valley. To attain the 2008 ozone NAAQS, the WMD 
will depend on continued emissions reductions in those areas.\10\
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    \10\ See CARB, Staff Report, ``CARB Review of the Mojave Desert 
AQMD and Antelope Valley AQMD Federal 75 ppb Ozone Attainment Plans 
for the Western Mojave Desert Nonattainment Area,'' April 21, 2017 
(``CARB Staff Report''), Appendix B, ``Weight of Evidence 
Analysis,'' B-28.
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C. CAA and Regulatory Requirements for 2008 8-Hour Ozone Nonattainment 
Area SIPs

    States must implement the 2008 ozone standards under title I, part 
D of the CAA, which includes sections 171-179B of subpart 1, 
``Nonattainment Areas in General,'' and sections 181-185 of subpart 2, 
``Additional Provisions for Ozone Nonattainment Areas.'' To assist 
states in developing effective plans to address ozone nonattainment 
problems, in 2015 the EPA issued a SIP Requirements Rule (SRR) for the 
2008 ozone standards (``2008 Ozone SRR'') that addresses requirements 
for nonattainment areas, such as attainment dates, emissions 
inventories, attainment and reasonable further progress (RFP) 
demonstrations, and the transition from the 1997 8-hour ozone standards 
to the 2008 8-hour ozone standards and associated anti-backsliding 
requirements.\11\ The 2008 Ozone SRR is codified at 40 CFR part 51, 
subpart AA. We discuss each of the CAA statutory and regulatory 
requirements for 2008 8-hour ozone plans in more detail in Section III 
of this document.
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    \11\ 80 FR 12264 (March 6, 2015).
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    The EPA's 2008 Ozone SRR was challenged, and on February 16, 2018, 
the U.S. Court of Appeals for the D.C. Circuit (``D.C. Circuit'') 
published its decision in South Coast Air Quality Management District 
v. EPA (``South Coast II'') \12\ vacating portions of the 2008 Ozone 
SRR. The only aspect of the South Coast II decision that affects this 
proposed action is the vacatur of the alternative baseline year for RFP 
plans. More specifically, the 2008 Ozone SRR required states to develop 
the baseline emissions inventory for RFP plans using the emissions 
inventory for the most recent calendar year for which states submit a 
triennial inventory to the EPA under subpart A of 40 CFR part 51, ``Air 
Emissions Reporting Requirements,'' which was 2011. The 2008 Ozone SRR, 
however, allowed states to use an alternative year, between 2008 and 
2012, for the baseline emissions inventory, provided the state 
demonstrated why the alternative baseline year was appropriate. In the 
South Coast II decision, the D.C. Circuit vacated the provisions of the 
2008 Ozone SRR that allowed states to use an alternative baseline year 
for demonstrating RFP.
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    \12\ South Coast Air Quality Management District v. EPA, 882 
F.3d 1138 (D.C. Cir. 2018). The term ``South Coast II'' is used in 
reference to the 2018 court decision to distinguish it from a 
decision published in 2006 also referred to as ``South Coast.'' The 
earlier decision involved a challenge to the EPA's Phase 1 
implementation rule for the 1997 ozone NAAQS. South Coast Air 
Quality Management Dist. v. EPA, 472 F.3d 882 (D.C. Cir. 2006).
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II. Submissions From the State of California To Address 2008 Ozone 
Standards Requirements in the West Mojave Desert

A. Summary of Submissions

1. 2016 WMD Attainment Plan
    On June 2, 2017, CARB submitted a SIP revision to address the WMD's 
planning obligations as a Severe-15 nonattainment area for the 2008 
ozone NAAQS.\13\ The June 2, 2017 submittal includes attainment plans 
prepared by the AVAQMD (``AVAQMD Attainment Plan'') \14\ and the MDAQMD 
(``MDAQMD Attainment Plan''),\15\ an accompanying staff report prepared 
by CARB (``CARB Staff Report''),\16\ and other supporting documents. We 
refer to the AVAQMD Attainment Plan and the MDAQMD Attainment Plan 
collectively as the Districts' ``Attainment Plans,'' and we refer to 
all the documents submitted to the EPA on June 2, 2017 as the ``2016 
WMD Attainment Plan.'' The 2016 WMD Attainment Plan addresses the 
requirements for base year and projected future year emissions 
inventories, air quality modeling demonstrating attainment of the 2008 
ozone NAAQS by the applicable attainment year, provisions demonstrating 
implementation of reasonably available control measures (RACM), 
provisions for transportation control strategies and measures, a 
demonstration of RFP, and contingency measures for failure to make RFP 
or to attain, among other requirements.
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    \13\ Letter dated June 2, 2017, from Richard Corey, CARB, to 
Alexis Strauss, EPA Region IX.
    \14\ AVAQMD, ``AVAQMD Federal 75 ppb Ozone Attainment Plan 
(Western Mojave Desert Nonattainment Area),'' adopted on March 21, 
2017.
    \15\ MDAQMD, ``MDAQMD Federal 75 ppb Ozone Attainment Plan 
(Western Mojave Desert Nonattainment Area),'' adopted on February 
27, 2017.
    \16\ CARB, Staff Report, ``CARB Review of the Mojave Desert AQMD 
and Antelope Valley AQMD Federal 75 ppb Ozone Attainment Plans for 
the Western Mojave Desert Nonattainment Area,'' released April 21, 
2017.
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2. CARB's 2018 Updates to the California State Implementation Plan
    On December 11, 2018, CARB submitted the ``2018 Updates to the 
California State Implementation Plan'' (``2018 SIP Update'') to the EPA 
as a revision to the California SIP.\17\ CARB adopted the 2018 SIP 
Update on October 25, 2018. CARB developed the 2018 SIP Update in 
response to the court's decision in South Coast II vacating the 2008 
Ozone SRR with respect to the use of an alternate baseline year for 
demonstrating RFP, and to address contingency measure requirements in 
the wake of the court decision in Bahr v. EPA.\18\ The 2018 SIP Update 
includes updates for 8 different California ozone nonattainment areas. 
We have previously approved portions of the 2018 SIP Update related to 
other

[[Page 24812]]

nonattainment areas.\19\ For the West Mojave Desert, the 2018 SIP 
Update includes an RFP demonstration using the required 2011 baseline 
year and revised motor vehicle emission budgets for the 2008 ozone 
NAAQS.\20\
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    \17\ Letter dated December 5, 2018, from Richard Corey, CARB, to 
Mike Stoker, EPA Region IX.
    \18\ Bahr v. EPA, 836 F.3d 1218 (9th Cir. 2016). In this case, 
the court rejected the EPA's longstanding interpretation of CAA 
section 172(c)(9) as allowing for early implementation of 
contingency measures. The court concluded that a contingency measure 
must take effect at the time the area fails to make RFP or attain by 
the applicable attainment date, not before. See also Sierra Club v. 
EPA, 985 F.3d 1055 (D.C. Cir. 2021), reaching a similar decision. 
These cases are addressed below in Section III.G of this document.
    \19\ See, e.g., 84 FR 11198 (March 25, 2019) (final approval of 
the San Joaquin Valley portion of the 2018 SIP Update) and 84 FR 
52005 (October 1, 2019) (final approval of the South Coast portion 
of the 2018 SIP Update).
    \20\ CARB withdrew the 2016 WMD Attainment Plan RFP 
demonstration in a letter dated December 18, 2019, from Richard 
Corey, CARB, to Michael Stoker, EPA Region IX.
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B. Clean Air Act Procedural Requirements for Adoption and Submission of 
SIP Revisions

1. Requirements
    CAA sections 110(a)(1) and (2) and 110(l) require a state to 
provide reasonable public notice and opportunity for public hearing 
prior to the adoption and submission of a SIP or SIP revision. To meet 
this requirement, every SIP submittal should include evidence that 
adequate public notice was given and an opportunity for a public 
hearing was provided consistent with the EPA's implementing regulations 
in 40 CFR 51.102.
2. Summary of the State's Documentation
a. 2016 WMD Attainment Plan
    On February 17, 2017, the AVAQMD published notice in a local 
newspaper of a public hearing to be held on March 21, 2017, for 
adoption of the AVAQMD Attainment Plan.\21\ The District held the 
public hearing on March 21, 2017,\22\ and signed a Board resolution 
adopting the plan that same day.\23\ The District sent the plan to CARB 
on April 18, 2017.\24\
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    \21\ Appendix B of Final Staff Report, Adoption of AVAQMD 
Attainment Plan.
    \22\ Minutes of the Governing Board of the Antelope Valley Air 
Quality Management District, Lancaster, California, March 21, 2017.
    \23\ Resolution 17-01, March 21, 2017.
    \24\ Letter dated April 18, 2017, from Alan J. De Salvio, 
AVAQMD, to Richard Corey, CARB.
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    On January 27, 2017, the MDAQMD published notice in a local 
newspaper of a public hearing to be held on February 27, 2017, for 
adoption of the MDAQMD Attainment Plan.\25\ The District held the 
public hearing on February 27, 2017,\26\ and signed a Board resolution 
adopting the plan the same day.\27\ The District sent the plan to CARB 
on April 3, 2017.\28\
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    \25\ Appendix B of Final Staff Report, MDAQMD Attainment Plan.
    \26\ Minutes of the Governing Board of the Mojave Desert Air 
Quality Management District, Victorville, California, February 27, 
2017.
    \27\ Resolution 17-05, dated February 27, 2017.
    \28\ Letter dated April 3, 2017, from Alan J. De Salvio, MDAQMD, 
to Richard Corey, CARB.
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    On April 20, 2017, CARB provided notice of a public comment period 
and public hearing to be held on May 25, 2017, for the 2016 WMD 
Attainment Plan.\29\ CARB adopted the 2016 WMD Attainment Plan by 
resolution at the May 25, 2017 hearing,\30\ and submitted it to the EPA 
on June 2, 2017.\31\ The EPA notified CARB the submittal was complete 
on November 22, 2017.\32\
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    \29\ Notice of Public Meeting to Consider the 2016 Ozone State 
Implementation Plan for the Western Mojave Desert Nonattainment 
Area, California Air Resources Board, April 20, 2017.
    \30\ Board Resolution 17-12, May 25, 2017.
    \31\ Letter dated June 2, 2017, from Richard Corey, CARB, to 
Alexis Strauss, EPA Region IX.
    \32\ Letter dated November 22, 2017, from Matt Lakin, EPA Region 
IX, to Richard Corey, CARB.
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b. 2018 SIP Update
    On September 21, 2018, CARB provided notice of a public comment 
period and public hearing to be held on October 25, 2018, for the 2018 
SIP Update.\33\ CARB adopted the 2018 SIP Update by resolution at the 
October 25, 2018 hearing,\34\ and submitted it the to the EPA in a 
letter dated December 5, 2018, which was electronically transmitted to 
the EPA's State Planning Electronic Collaboration System on December 
11, 2018.\35\
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    \33\ Notice of Public Meeting to Consider the 2018 Updates to 
the California State Implementation Plan, September 21, 2018.
    \34\ Board Resolution 18-50, October 25, 2018.
    \35\ Letter dated December 5, 2018, from Richard Corey, CARB, to 
Mike Stoker, EPA Region IX.
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c. The EPA's Conclusions on the Submission Requirements for the WMD 
2016 Attainment Plan
    CARB has satisfied the applicable statutory and regulatory 
requirements for reasonable public notice and hearing prior to the 
adoption and submittal of the elements of the 2016 WMD Attainment Plan. 
Based on information provided in each SIP revision and summarized 
above, the EPA has determined that all hearings were properly noticed. 
Therefore, we find that the submittals of the 2016 WMD Attainment Plan 
meet the procedural requirements for public notice and hearing in CAA 
sections 110(a) and 110(l) and 40 CFR 51.102.

III. Evaluation of the 2016 WMD Attainment Plan and 2018 SIP Update

A. Emission Inventories

1. Statutory and Regulatory Requirements
    Sections 172(c)(3) and 182(a)(1) of the CAA require states to 
submit for each ozone nonattainment area a ``base year inventory'' that 
is a comprehensive, accurate, current inventory of actual emissions 
from all sources of the relevant pollutant or pollutants in the area. 
In addition, the 2008 Ozone SRR requires that the inventory year be 
selected consistent with the baseline year for the RFP demonstration, 
which is usually the most recent calendar year for which a complete 
triennial inventory is required to be submitted to the EPA under the 
Air Emissions Reporting Requirements.\36\ The EPA has issued guidance 
on the development of base year and future year emissions inventories 
for 8-hour ozone and other pollutants.\37\ Emissions inventories for 
ozone must include emissions of VOC and NOX and represent 
emissions for a typical ozone season weekday.\38\ States should include 
documentation explaining how the emissions data were calculated. In 
estimating mobile source emissions, states should use the latest 
emissions models and planning assumptions available at the time the SIP 
is developed.\39\
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    \36\ 2008 Ozone SRR at 40 CFR 51.1115(a) and the Air Emissions 
Reporting Requirements at 40 CFR part 51 subpart A.
    \37\ ``Emissions Inventory Guidance for Implementation of Ozone 
and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' EPA-454/B-17-002, May 2017. 
At the time the 2016 WMD Attainment Plan was developed, the 
following EPA emissions inventory guidance applied: ``Emissions 
Inventory Guidance for Implementation of Ozone and Particulate 
Matter National Ambient Air Quality Standards (NAAQS) and Regional 
Haze Regulations,'' EPA-454/R-05-001, August 2005.
    \38\ 40 CFR 51.1115(a) and (c), and 40 CFR 51.1100(bb) and (cc).
    \39\ 80 FR 12264, 12290 (March 6, 2015).
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    Future year baseline emissions inventories must reflect the most 
recent population, employment, travel, and congestion estimates for the 
area. In this context, ``baseline'' emissions inventories refer to 
emissions estimates for a given year and area that reflect rules and 
regulations and other measures that are already adopted. Future year 
baseline emissions inventories are necessary to show the projected 
effectiveness of SIP control measures. Both the base year and future 
year inventories are necessary for photochemical modeling to 
demonstrate attainment.
2. Summary of State's Submission
    The 2016 WMD Attainment Plan includes base year (2012) and future 
year baseline inventories for NOX and VOC for the West 
Mojave Desert.\40\

[[Page 24813]]

Documentation for the inventories is found in Appendix A-2 of the CARB 
Staff Report.\41\ The emissions inventories represent average summer 
day emissions, consistent with the observation that ozone levels in 
West Mojave Desert are typically higher from May through October.\42\ 
For stationary and area sources, the 2012 base year and future year 
inventories considered several of the Districts' rules, specifically 
including MDAQMD Rule 1461, ``Portland Cement Kilns'' (covering mineral 
processing), and rules from both Districts based on CARB's rules for 
consumer products, aerosol coatings,\43\ and architectural 
coatings.\44\ The inventory also specifically notes the incorporation 
of CARB's performance standards for gasoline dispensing hose 
permeation,\45\ and revised vehicle refueling emission factors.\46\ 
These District and CARB rules are noted in Table 5, ``Stationary Source 
Control Rules and Regulations Included in the Inventory,'' of Appendix 
A-1 of the CARB Staff Report. The mobile source portions of both base 
year and projected future year inventories were developed using 
California's EPA-approved mobile source emissions model, EMFAC2014, for 
estimating on-road motor vehicle emissions.\47\
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    \40\ The 2012 base year and future year baseline emissions 
inventories in the CARB Staff Report exclude non-anthropogenic 
``natural sources'' emissions such as biogenics and geogenics. 
However, emissions from such natural sources are included in the 
emissions inventories used for the attainment demonstration because 
they affect ozone formation.
    \41\ The 2012 base year emissions inventory included in the CARB 
Staff Report supersedes and replaces a previous submittal of the 
2012 base year emissions inventory for the West Mojave Desert in the 
``8-Hour Ozone State Implementation Plan Emission Inventory 
Submittal'' (the ``Multi-Area Emission Inventory''). The Multi-Area 
Emission Inventory was submitted by CARB on July 17, 2014 and later 
withdrawn on December 18, 2019. The Multi-Area Inventory included 
2012 base year emissions inventories for 16 nonattainment areas, 
including the West Mojave Desert. Relative to the corresponding 
inventory for the West Mojave Desert in the Multi-Area Emission 
Inventory, the 2012 base year emissions inventory in the 2016 WMD 
Attainment Plan reflects updated stationary, area, and nonroad 
source calculations as well as an updated version of the EMFAC model 
for on-road motor vehicle estimates.
    \42\ Appendix A-2 of the CARB Staff Report. In contrast, the 
emissions inventory and projections in Appendix A and B of the 
Districts' Attainment Plans contain average daily emissions, not 
average summer day emissions.
    \43\ See California Code of Regulations 94522, ``Limits and 
Requirements for Aerosol Coating Products,'' incorporated into the 
SIP on November 4, 2009 (74 FR 57074).
    \44\ As stated on the CARB website (https://ww2.arb.ca.gov/our-work/programs/coatings/architectural-coatings/scm-district-rulemaking-schedule, accessed on August 25, 2020), AVAQMD Rule 1113, 
adopted locally on June 18, 2013 and MDAQMD Rule 1113, adopted 
locally on April 23, 2012, implement California's 2007 suggested 
control measures for architectural coatings. These rules were 
incorporated into the SIP on December 8, 2015 (80 FR 76222) and 
December 8, 2015 (80 FR 76222), respectively.
    \45\ See https://ww3.arb.ca.gov/vapor/gdf-emisfactor/attachment5.pdf.
    \46\ See https://ww2.arb.ca.gov/gasoline-dispensing-facility-emission-factors.
    \47\ EMFAC is short for EMission FACtor.
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    The 2016 WMD Attainment Plan includes emissions inventories for 
stationary sources, area sources, and on-road and off-road mobile 
sources.\48\ Stationary sources refer to larger ``point'' sources that 
have a fixed geographic location. The 2018 SIP Update explains that 
2012 ``stationary source emissions reflect actual emissions reported 
from industrial point sources'' and include stationary aggregate 
sources, such as gasoline dispensing facilities.\49\ AVAQMD Rule 107, 
``Certification of Submissions and Emission Statements,'' and MDAQMD 
Rule 107, ``Certification and Emission Statements,'' require all 
stationary sources within the nonattainment area that emit more than 25 
tons per year (tpy) or more of VOC or NOX to report and 
certify annual emissions. For the 2012 base year, CARB developed a list 
of stationary sources in Los Angeles and San Bernardino counties and 
their associated emissions. AVAQMD and MDAQMD separated the stationary 
sources within the WMD from those within their respective counties but 
outside the WMD.
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    \48\ CARB Staff Report, Appendix A-2.
    \49\ 2018 SIP Update, Appendix A, A-1.
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    Area sources include smaller emissions sources distributed across 
the nonattainment area, such as consumer products, architectural 
coatings, pesticides and herbicides, farming operations, and cooking. 
CARB and the District estimate emissions for area sources using surveys 
and information from other state and federal agencies. These estimates 
are updated with relevant factors such as population changes, 
demographic factors, and agency specific growth factors (e.g., for 
farming operations and use of herbicides and pesticides).\50\
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    \50\ CARB Staff Report, see the discussion of areawide sources 
beginning on page A1-8.
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    On-road emissions inventories in the CARB Staff Report are 
calculated using CARB's EMFAC2014 model \51\ and the travel activity 
data provided by the area's metropolitan planning organization, the 
Southern California Association of Governments (SCAG), in the ``2016-
2040 Regional Transportation Plan/Sustainable Communities Strategy.'' 
\52\ CARB consulted with MDAQMD staff to estimate emissions from off-
road equipment and area sources occurring in the nonattainment area, 
most often using human population as default surrogate for the quantity 
of emissions occurring in the WMD.\53\ Future emissions forecasts are 
primarily based on population and economic growth projections provided 
by SCAG; growth estimates from government agencies such as the U.S. 
Bureau of Labor Statistics, the U.S. Department of Agriculture, and 
CARB; forecasts from the Districts; and research studies. The growth 
factors for each emissions category are discussed in Appendix A-1 of 
the CARB Staff Report.
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    \51\ In December 2015, the EPA approved EMFAC2014 for SIP 
development and transportation conformity purposes in California. 80 
FR 77337 (December 14, 2015). EMFAC2014 was the most recently 
approved version of the EMFAC model that was available at the time 
of preparation of the 2016 Attainment Plan. The EPA approved an 
updated version of the EMFAC model, EMFAC2017, for future SIP 
development and transportation purposes in California. 84 FR 41717 
(August 15, 2019).
    \52\ CARB Staff Report, Appendix A-1.
    \53\ Id. at A1-3.
---------------------------------------------------------------------------

    Table 1 below provides a summary of the CARB Staff Report's 2012 
base year and future attainment year VOC and NOX emissions 
estimates within the West Mojave Desert (average summer day). These 
inventories provide the basis for the control measure analysis and the 
attainment demonstration in the 2016 WMD Attainment Plan. Based on the 
inventory for 2012, stationary and area sources of VOC emissions are 
roughly equivalent to the combined on-road and off-road mobile source 
emissions. For NOX emissions in 2012, on-road mobile sources 
contribute the highest fraction of emissions (37.11 tons per day (tpd) 
or 37.5 percent) followed by off-road (32.53 tpd or 32.9 percent), 
stationary (28.27 tpd or 28.6 percent), and area sources (1.05 tpd or 
1.1 percent).

[[Page 24814]]

     Table 1--West Mojave Desert Nonattainment Area Base Year and Attainment Year Emissions Inventory Summary
                                           [Summer season average tpd]
----------------------------------------------------------------------------------------------------------------
                                                    NOX  (2012)     NOX  (2026)
                     Category                                                       VOC  (2012)     VOC  (2026)
----------------------------------------------------------------------------------------------------------------
Stationary Sources..............................           28.27           42.08           13.16           17.35
Area Sources....................................            1.05            0.92           11.32           12.15
On-road Mobile..................................           37.11            9.84           15.21            5.98
Off-road Mobile.................................           32.53           25.53            7.09            4.99
                                                 ---------------------------------------------------------------
    Total.......................................           98.95           68.56           46.78           40.47
----------------------------------------------------------------------------------------------------------------
Source: Appendix A-2, CARB Staff Report. Due to rounding, the totals may not agree to the hundredth of a tpd.

3. The EPA's Review of the State's Submission
    We have reviewed the 2012 base year emissions inventory in the 2016 
WMD Attainment Plan and the inventory methodologies used by CARB and 
the District for consistency with CAA requirements and EPA guidance. 
First, as required by EPA regulations, we find that the 2012 inventory 
includes estimates for VOC and NOX for a typical ozone 
season weekday, and that CARB has provided adequate documentation 
explaining how the emissions are calculated. Second, we find that the 
2012 base year emissions inventory in the 2016 WMD Attainment Plan 
reflects appropriate emissions models and methodologies, and, 
therefore, represents a comprehensive, accurate, and current inventory 
of actual emissions during that year in the WMD. Third, we find that 
selection of year 2012 for the base year emissions inventory is 
appropriate because it is consistent with the 2011 RFP baseline year 
(from the 2018 SIP Update) because both inventories are derived from a 
common set of models and methods. Therefore, the EPA is proposing to 
approve the 2012 emissions inventory in the 2016 WMD Attainment Plan as 
meeting the requirements for a base year inventory set forth in CAA 
section 182(a)(1) and 40 CFR 51.1115.
    With respect to future year baseline projections, we have reviewed 
the growth and control factors and find them acceptable, and conclude 
that the future baseline emissions projections in the 2016 WMD 
Attainment Plan reflect appropriate calculation methods and the latest 
planning assumptions.
    Furthermore, we note that the future year baseline projections 
account for emissions reductions from control measures in adopted state 
and local rules and regulations. As a general matter, the EPA will 
approve a SIP revision that takes emissions reduction credit for such 
control measures only where the EPA has approved the control measures 
as part of the SIP. Tables 1 and 2 in the technical support document 
(TSD) supporting this action document the approval of all rules within 
the West Mojave Desert. Table 5 of the CARB Staff Report documents the 
specific rules considered in the development of the emissions 
inventory.
    With respect to mobile sources, the EPA has taken action in recent 
years to approve CARB mobile source regulations into the California 
SIP.\54\ We therefore find that the future year baseline projections in 
the 2016 WMD Attainment Plan are properly supported by SIP-approved 
stationary and mobile source control measures.
---------------------------------------------------------------------------

    \54\ See 81 FR 39424 (June 16, 2016), 82 FR 14446 (March 21, 
2017), and 83 FR 23232 (May 18, 2018).
---------------------------------------------------------------------------

B. Emissions Statements

1. Statutory and Regulatory Requirements
    Section 182(a)(3)(B)(i) of the Act requires each state to submit a 
SIP revision requiring owners or operators of stationary sources of VOC 
or NOX to provide the state with statements of actual 
emissions from such sources. Statements must be submitted at least 
every year and must contain a certification that the information 
contained in the statement is accurate to the best knowledge of the 
individual certifying the statement. Section 182(a)(3)(B)(ii) of the 
Act allows states to waive the emission statement requirement for any 
class or category of stationary sources that emit less than 25 tpy of 
VOC or NOX, if the state provides an inventory of emissions 
from such class or category of sources as part of the base year or 
periodic inventories required under CAA sections 182(a)(1) and 
182(a)(3)(A), based on the use of emission factors established by the 
EPA or other methods acceptable to the EPA.
    The preamble of the 2008 Ozone SRR states that if an area has a 
previously approved emissions statement rule for the 1997 ozone NAAQS 
or the 1-hour ozone NAAQS that covers all portions of the nonattainment 
area for the 2008 ozone NAAQS, such rule should be sufficient for 
purposes of the emissions statement requirement for the 2008 ozone 
NAAQS.\55\ The state should review the existing rule to ensure it is 
adequate and, if so, may rely on it to meet the emissions statement 
requirement for the 2008 ozone NAAQS. Where an existing emissions 
statement requirement is still adequate to meet the requirements of 
this rule, states can provide the rationale for that determination to 
the EPA in a written statement in the SIP to meet this requirement. 
States should identify the various requirements and how each is met by 
the existing emissions statement program. Where an emissions statement 
requirement is modified for any reason, the state must provide the 
revisions to the emissions statement as part of its SIP.
---------------------------------------------------------------------------

    \55\ 80 FR 12264, at 12291 (March 6, 2015).
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The 2016 WMD Attainment Plan addresses compliance with the 
emissions statement requirement in CAA section 182(a)(3)(B) for the 
2008 ozone NAAQS by reference to AVAQMD Rule 107 and MDAQMD Rule 
107.\56\ These rules require, among other things, emissions reporting 
within the West Mojave Desert from all stationary sources of 
NOX and VOC with emissions over 25 tpy.\57\ The EPA approved 
AVAQMD Rule 107 on April 11, 2013 (78 FR 21545) and MDAQMD Rule 107 on 
May 26, 2004 (69 FR 29880) as revisions to each District's portion of 
the California SIP. AVAQMD and MDAQMD letters to CARB state that these 
rules continue to meet the emission statement requirements of CAA 
section 182(a)(3)(B) and that the Districts rely on these rules to meet 
the

[[Page 24815]]

emissions statement requirements for the 2008 ozone standards.\58\
---------------------------------------------------------------------------

    \56\ Addendum A to Appendix D and Addendum A to Appendix E of 
the CARB Staff Report.
    \57\ Id.
    \58\ Appendix D1 and D2 and Appendix E1 and E1 of the CARB Staff 
Report.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    For this action, we have reviewed AVAQMD Rule 107 and MDAQMD Rule 
107 for compliance with the specific requirements for emissions 
statement rules under CAA section 182(a)(3)(B). We agree with the 
Districts' findings: That these rules apply within the entire ozone 
nonattainment area and that the nonattainment area is the same for both 
the 1997 Ozone NAAQS and the 2008 ozone NAAQS; that the rules apply to 
all stationary sources of VOC and NOX, except those emitting 
less than 25 tpy for which the Districts have waived the requirement 
(consistent with CAA section 182(a)(3)(B)(ii)); and that the rules 
require reporting, on an annual basis, of total emissions of VOC and 
NOX. We also find that AVAQMD Rule 107 and MDAQMD Rule 107 
require certification that the information provided to the Districts is 
accurate to the best knowledge of the individual certifying the 
emissions data, as required under CAA section 182(a)(3)(B).
    Therefore, we propose to approve the emissions statement element of 
the 2016 WMD Attainment Plan as meeting the requirements of CAA section 
182(a)(3)(B) and the 40 CFR 51.1102.

C. Reasonably Available Control Measures Demonstration

1. Statutory and Regulatory Requirements
    CAA section 172(c)(1) requires that each attainment plan provide 
for the implementation of all RACM as expeditiously as practicable 
(including such reductions in emissions from existing sources in the 
area as may be obtained through implementation of reasonably available 
control technology (RACT)), and also provide for attainment of the 
NAAQS. The 2008 Ozone SRR requires that, for each nonattainment area 
required to submit an attainment demonstration, the state concurrently 
submit a SIP revision demonstrating that it has adopted all RACM 
necessary to demonstrate attainment as expeditiously as practicable and 
to meet any RFP requirements.\59\
---------------------------------------------------------------------------

    \59\ 40 CFR 51.1112(c).
---------------------------------------------------------------------------

    The EPA has previously provided guidance interpreting the RACM 
requirement in the General Preamble for the Implementation of the Clean 
Air Act Amendments of 1990 (``General Preamble'') and in a memorandum 
entitled ``Guidance on the Reasonably Available Control Measures (RACM) 
Requirement and Attainment Demonstration Submissions for Ozone 
Nonattainment Areas.'' \60\ In summary, to address the requirement to 
adopt all RACM, states should consider all potentially reasonable 
control measures for source categories in the nonattainment area to 
determine whether they are reasonably available for implementation in 
that area and whether they would, if implemented individually or 
collectively, advance the area's attainment date by one year or 
more.\61\ Any measures that are necessary to meet these requirements 
that are not already either federally promulgated, or part of the 
state's SIP, or otherwise creditable in the SIP, must be submitted in 
enforceable form as part of the state's attainment plan for the 
area.\62\
---------------------------------------------------------------------------

    \60\ General Preamble, 57 FR 13498 at 13560 (April 16, 1992); 
memorandum dated November 30, 1999, from John Seitz, Director, 
OAQPS, to EPA Regional Air Directors, Regions I-X, Subject: 
``Guidance on the Reasonably Available Control Measures (RACM) 
Requirement and Attainment Demonstration Submissions for Ozone 
Nonattainment Areas.''
    \61\ Id. See also 44 FR 20372 (April 4, 1979), and memorandum 
dated December 14, 2000, from John S. Seitz, Director, OAQPS, to 
Regional Air Directors, titled ``Additional Submission on RACM From 
States with Severe One-Hour Ozone Nonattainment Area SIPs.''
    \62\ For ozone nonattainment areas classified as Moderate or 
above, CAA section 182(b)(2) also requires implementation of RACT 
for all major sources of VOC and for each VOC source category for 
which the EPA has issued a Control Techniques Guideline (CTG). CAA 
section 182(f) requires that RACT under section 182(b)(2) also apply 
to major stationary sources of NOX. In Extreme areas, a 
major source is a stationary source that emits or has the potential 
to emit at least 10 tpy of VOC or NOX (see CAA section 
182(e) and (f)). Under the 2008 Ozone SRR, states were required to 
submit SIP revisions meeting the RACT requirements of CAA sections 
182(b)(2) and 182(f) no later than 24 months after the effective 
date of designation for the 2008 Ozone NAAQS and to implement the 
required RACT measures as expeditiously as practicable but no later 
than January 1 of the 5th year after the effective date of 
designation (see 40 CFR 51.1112(a)). California submitted the CAA 
section 182 RACT SIP for AVAQMD and MDAQMD on October 23, 2015 and 
September 9, 2015, respectively. The EPA conditionally approved 
these submissions at 82 FR 46923 (October 10, 2017) and 83 FR 5921 
(February 12, 2018).
---------------------------------------------------------------------------

    CAA section 172(c)(6) requires that nonattainment area plans 
include enforceable emission limitations, and such other control 
measures, means or techniques (including economic incentives such as 
fees, marketable permits, and auctions of emission rights), as well as 
schedules and timetables for compliance, as may be necessary or 
appropriate to provide for timely attainment of the NAAQS.\63\ Under 
the 2008 Ozone SRR, all control measures needed for attainment must be 
implemented no later than the beginning of the attainment year ozone 
season.\64\ The attainment year ozone season is defined as the ozone 
season immediately preceding a nonattainment area's outermost 
attainment date.\65\
---------------------------------------------------------------------------

    \63\ See also CAA section 110(a)(2)(A).
    \64\ 40 CFR 51.1108(d).
    \65\ 40 CFR 51.1100(h).
---------------------------------------------------------------------------

2. Summary of the State's Submission
a. The Districts' RACM Analysis
    The AVAQMD and MDAQMD Attainment Plans explain that they 
incorporate all RACM, and that the Districts have adopted or committed 
in the Attainment Plans to adopt all such measures.\66\ The Plans note 
the Districts' reviews of stationary source rules conducted during the 
development of the RACT SIPs submitted to the EPA in 2015,\67\ and set 
out the Districts' schedules for adoption of rules identified in those 
reviews.\68\ The CARB Staff Report includes a further RACM assessment 
from each District confirming that the Districts have examined existing 
control measures and determined that no additional RACT or mobile 
source controls will advance the attainment date for the West Mojave 
Desert for the 2008 ozone standard.\69\ These assessments also note 
that photochemical modeling shows the WMD would attain the ozone NAAQS 
if not for upwind emissions from the South Coast Air Basin and San 
Joaquin Valley.\70\
---------------------------------------------------------------------------

    \66\ AVAQMD Attainment Plan, 6-7, and MDAQMD Attainment Plan, 7.
    \67\ ``2015 8-Hour Ozone Reasonably Available Control Technology 
(RACT) SIP Analysis: Antelope Valley Air Quality Management 
District'' and ``2015 8-Hour Ozone Reasonably Available Control 
Technology (RACT) SIP Analysis: Mojave Desert Air Quality Management 
District.'' The EPA conditionally approved these submissions at 82 
FR 46923 (October 10, 2017) and 83 FR 5921 (February 12, 2018), 
respectively.
    \68\ AVAQMD Attainment Plan, 17, and MDAQMD Attainment Plan, 19.
    \69\ CARB Staff Report, Appendix D-3 and E-3. See also CARB 
Staff Report, 10.
    \70\ CARB Staff Report, Appendix D-3 and E-3. This finding is 
supported by Appendix B of the CARB Staff Report, which contains a 
conceptual model explaining the formation of ozone in the WMD, and 
the heavy influence of transport from the South Coast Air Basin.
---------------------------------------------------------------------------

b. CARB'S RACM Analysis
    Source categories for which CARB has primary jurisdiction for 
reducing emissions in California include most new and existing on- and 
off-road engines and vehicles, motor vehicle fuels, and consumer 
products. CARB's RACM assessment is contained in the Appendix E, 
``Ozone RACM Assessment,'' of both the AVAQMD and MDAQMD Attainment 
Plans. Appendix

[[Page 24816]]

F, ``CARB Adopted Mobile Source Programs,'' of these attainment plans 
also includes a general description of CARB's key mobile source 
regulations and programs and a comprehensive table listing on- and off-
road mobile source regulatory actions taken by CARB from 1985 through 
2016. The RACM assessment contains CARB's evaluation of mobile source 
and other statewide control measures that reduce emissions of 
NOX and VOC in the WMD.
    Given the need for substantial emissions reductions from mobile and 
area sources to meet the NAAQS in California nonattainment areas, CARB 
has established stringent control measures for on-road and off-road 
mobile sources and the fuels that power them. California has unique 
authority under CAA section 209 (subject to a waiver by the EPA) to 
adopt and implement new emission standards for many categories of on-
road vehicles and engines, and new and in-use off-road vehicles and 
engines.
    CARB's mobile source program extends beyond regulations that are 
subject to the waiver or authorization process set forth in CAA section 
209, to include standards and other requirements to control emissions 
from in-use heavy-duty trucks and buses, gasoline and diesel fuel 
specifications, and many other types of mobile sources. Generally, 
these regulations have been submitted and approved as revisions to the 
California SIP.\71\
---------------------------------------------------------------------------

    \71\ See, e.g., the EPA's approval of standards and other 
requirements to control emissions from in-use heavy-duty diesel-
powered trucks, at 77 FR 20308 (April 4, 2012), revisions to the 
California on-road reformulated gasoline and diesel fuel regulations 
at 75 FR 26653 (May 12, 2010), and revisions to the California motor 
vehicle inspection and maintenance program at 75 FR 38023 (July 1, 
2010).
---------------------------------------------------------------------------

    The Districts' Attainment Plans include CARB's RACM analysis for 
mobile source measures in the West Mojave Desert. In this analysis, 
CARB concludes:

    There are no reasonable regulatory control measures excluded 
from use in this plan; therefore, there are no emissions reductions 
associated with unused regulatory control measures. As a result, 
California's mobile source control programs fully meet the 
requirements for RACM.\72\
---------------------------------------------------------------------------

    \72\ AVAQMD Attainment Plan, Appendix E-7; MDAQMD Attainment 
Plan, Appendix E-7.
---------------------------------------------------------------------------

c. Local Jurisdictions' RACM Analysis and Transportation Control 
Measures
    The supplemental RACM assessments included as addendums to 
appendices D and E of the CARB Staff Report address the Districts' RACM 
findings, including for transportation control measures (TCMs). These 
addendums state that the Districts examined existing control measures 
and determined that controls from RACT and mobile source emission 
control programs will not advance the West Mojave Desert's attainment 
year for the 2008 ozone standards.\73\
---------------------------------------------------------------------------

    \73\ CARB Staff Report, Appendix D-3 and E-3.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    The TSD for this action includes additional analysis to evaluate 
the Districts' and CARB's RACM assessments.\74\ In that analysis, we 
estimate that a 1.2 tpd reduction of NOX emissions would be 
necessary to advance attainment by one year from 2026 to 2025, and 
conservatively identify no more than 1.04 tpd of additional reductions 
that could be achieved through implementation of potential RACM for 
stationary sources. Based on this analysis, we agree with the 
Districts' and CARB's conclusion that there are no additional RACM that 
would advance attainment of the 2008 ozone standards in the WMD by at 
least one year.
---------------------------------------------------------------------------

    \74\ Technical Support Document, Clean Air Plans; 2008 8-Hour 
Ozone Nonattainment Area Requirements; West Mojave Desert, 
California, U.S. EPA Region IX, September 2020.
---------------------------------------------------------------------------

    We also find that CARB's consumer products program comprehensively 
addresses emissions from consumer products in the WMD. CARB measures 
are more stringent than the EPA's consumer products regulation 
promulgated in 1998,\75\ and generally exceed the controls in place 
throughout other areas of the country. We agree with CARB's conclusion 
that its mobile source regulations include all reasonably available 
controls.
---------------------------------------------------------------------------

    \75\ 63 FR 48819 (September 11, 1998).
---------------------------------------------------------------------------

    For the WMD, given the significant influence of pollutant transport 
from the South Coast Air Basin and the minimal and diminishing 
emissions benefits generally associated with TCMs, no new TCMs 
implemented in the WMD, alone or in combination with potential 
additional rules, would contribute to advancing the attainment date in 
the WMD by one year. Therefore, no new TCMs are required to satisfy the 
RACM requirement in the WMD.
    For the foregoing reasons, and as addressed more fully in the TSD 
for this action, we propose to find that the 2016 Attainment Plan 
provides for the implementation of all RACM as required by CAA section 
172(c)(1) and 40 CFR 51.1112(c).

D. Attainment Demonstration

1. Statutory and Regulatory Requirements
    An attainment demonstration consists of the following: (1) 
Technical analyses, such as base year and future year modeling, to 
locate and identify sources of emissions that are contributing to 
violations of the ozone NAAQS within the nonattainment area (i.e., 
analyses related to the emissions inventory for the nonattainment area 
and the emissions reductions necessary to attain the standard); (2) a 
list of adopted measures (including RACT controls) with schedules for 
implementation and other means and techniques necessary and appropriate 
for demonstrating RFP and attainment as expeditiously as practicable 
but no later than the outside attainment date for the area's 
classification; (3) a RACM analysis; and (4) contingency measures 
required under sections 172(c)(9) and 182(c)(9) of the CAA that can be 
implemented without further action by the state or the EPA to cover 
emissions shortfalls in RFP plans and failures to attain.\76\ This 
subsection of this proposed rule addresses the first two components of 
the attainment demonstration--the technical analyses and a review of 
adopted measures. Section III.C of this document, ``Reasonably 
Available Control Measures Demonstration,'' addresses the RACM 
component, and section III.G, ``Contingency Measures,'' addresses the 
contingency measures component of the attainment demonstration in the 
Attainment Plans.
---------------------------------------------------------------------------

    \76\ 78 FR 34178, 34184 (June 6, 2013), the EPA's proposed rule 
for implementing the 2008 ozone NAAQS.
---------------------------------------------------------------------------

    With respect to the technical analyses, section 182(c)(2)(A) of the 
CAA requires that a plan for an ozone nonattainment area classified 
``Serious'' or above include a ``demonstration that the plan . . . will 
provide for attainment of the ozone [NAAQS] by the applicable 
attainment date. This attainment demonstration must be based on 
photochemical grid modeling or any other analytical method determined . 
. . to be at least as effective.'' The attainment demonstration 
predicts future ambient concentrations for comparison to the NAAQS, 
making use of available information on measured concentrations, 
meteorology, and current and projected emissions inventories of ozone 
precursors, including the effect of control measures in the plan. Areas 
classified Severe-15 for the 2008 ozone NAAQS must demonstrate 
attainment as expeditiously as practicable, but no later than 15 years

[[Page 24817]]

after the effective date of designation as nonattainment. The WMD was 
designated nonattainment for the 2008 ozone NAAQS effective July 20, 
2012,\77\ and accordingly must demonstrate attainment of the standards 
by no later than July 20, 2027.\78\ An attainment demonstration must 
show attainment of the standards for a full calendar year before the 
attainment date, so in practice, Severe-15 nonattainment areas must 
demonstrate attainment no later than 2026.
---------------------------------------------------------------------------

    \77\ 77 FR 30088 (May 21, 2012).
    \78\ 80 FR 12264 (March 6, 2015).
---------------------------------------------------------------------------

    The EPA's recommended procedures for modeling ozone as part of an 
attainment demonstration are contained in ``Modeling Guidance for 
Demonstrating Attainment of Air Quality Goals for Ozone, 
PM2.5, and Regional Haze'' (``Modeling Guidance'').\79\ The 
Modeling Guidance includes recommendations for a modeling protocol, 
model input preparation, model performance evaluation, use of model 
output for the numerical NAAQS attainment test, and modeling 
documentation. Air quality modeling is performed using meteorology and 
emissions from a base year, and the predicted concentrations from this 
base case modeling are compared to air quality monitoring data from 
that year to evaluate model performance. Once the model performance is 
determined to be acceptable, future year emissions are simulated with 
the model. The relative (or percent) change in modeled concentration 
due to future emissions reductions provides a relative response factor 
(RRF). Each monitoring site's RRF is applied to its monitored base year 
design value to provide the future design value for comparison to the 
NAAQS. The Modeling Guidance also recommends supplemental air quality 
analyses, which may be used as part of a weight of evidence (WOE) 
analysis. A WOE analysis corroborates the attainment demonstration by 
considering evidence other than the main air quality modeling 
attainment test, such as trends and additional monitoring and modeling 
analyses.
---------------------------------------------------------------------------

    \79\ ``Modeling Guidance for Demonstrating Attainment of Air 
Quality Goals for Ozone, PM2.5, and Regional Haze,'' EPA 
454/R-18-009 (November 2018); available at https://www.epa.gov/scram/state-implementation-plan-sip-attainment-demonstration-guidance. See also December 2014 draft of this guidance, available 
at the same website. The December 2014 draft guidance was available 
during development of the Plan; the final version differs mainly in 
organization, and in updates to the regional haze portion and to 
other document references. Additional EPA modeling guidance can be 
found in 40 CFR 51 Appendix W, Guideline on Air Quality Models, 82 
FR 5182 (January 17, 2017); available at https://www.epa.gov/scram/clean-air-act-permit-modeling-guidance.
---------------------------------------------------------------------------

    The Modeling Guidance also does not require a particular year to be 
used as the base year for 8-hour ozone plans.\80\ The Modeling Guidance 
states that the most recent year of the National Emissions Inventory 
may be appropriate for use as the base year for modeling, but that 
other years may be more appropriate when considering meteorology, 
transport patterns, exceptional events, or other factors that may vary 
from year to year.\81\ Therefore, the base year used for the attainment 
demonstration need not be the same year used to meet the requirements 
for emissions inventories and RFP.
---------------------------------------------------------------------------

    \80\ Modeling Guidance at section 2.7.1, 35.
    \81\ Id.
---------------------------------------------------------------------------

    With respect to the list of adopted measures, CAA section 172(c)(6) 
requires that nonattainment area plans include enforceable emissions 
limitations, and such other control measures, means or techniques 
(including economic incentives such as fees, marketable permits, and 
auctions of emission rights), as well as schedules and timetables for 
compliance, as may be necessary or appropriate to provide for timely 
attainment of the NAAQS.\82\ Under the 2008 Ozone SRR, all control 
measures needed for attainment must be implemented no later than the 
beginning of the attainment year ozone season.\83\ The attainment year 
ozone season is defined as the ozone season immediately preceding a 
nonattainment area's outermost attainment date.\84\ For the West Mojave 
Desert, the outermost attainment year is 2026.
---------------------------------------------------------------------------

    \82\ See also CAA section 110(a)(2)(A).
    \83\ 40 CFR 51.1108(d).
    \84\ 40 CFR 51.1100(h).
---------------------------------------------------------------------------

2. Summary of the State's Submission
a. Photochemical Modeling
    The 2016 WMD Attainment Plan includes photochemical modeling for 
the 2008 ozone NAAQS. The South Coast Air Quality Management District 
(SCAQMD) performed the air quality modeling for the 2016 WMD Attainment 
Plan, as part of the Final 2016 Air Quality Management Plan for the 
South Coast Air Quality Management District (``SCAQMD 2016 AQMP'').\85\ 
The modeling relies on a 2012 base year and demonstrates attainment of 
the 2008 ozone NAAQS by the applicable Severe-15 area attainment year 
(i.e., 2026).
---------------------------------------------------------------------------

    \85\ Appendix V, Final 2016 Air Quality Management Plan, March 
2017, SCAQMD. See AVAQMD Attainment Plan, 31, and MDAQMD Attainment 
Plan, 33.
---------------------------------------------------------------------------

    The modeling and modeled attainment demonstration are described in 
Chapter 4, ``Attainment Demonstration,'' of the 2016 WMD Attainment 
Plan and in Appendix D, ``Western Mojave Desert Modeling Analysis.'' 
The AVAQMD Attainment Plan and the MDAQMD Attainment Plan also 
reference Appendix V of the SCAQMD 2016 AQMP for additional information 
on the modeled attainment demonstration.
    The modeling protocol is in Chapter 2, ``Modeling Protocol,'' of 
Appendix V of the SCAQMD 2016 AQMP and contains all the elements 
recommended in the Modeling Guidance. Those include the following: 
Selection of model, time period to model, modeling domain, and model 
boundary conditions and initialization procedures; a discussion of 
emissions inventory development and other model input preparation 
procedures; model performance evaluation procedures; selection of days; 
and other details for calculating RRFs. Appendix V of the SCAQMD 2016 
AQMP also provides the coordinates of the modeling domain and 
thoroughly describes the development of the modeling emissions 
inventory, its spatial and temporal allocation, its temperature 
dependence, and quality assurance procedures.
    The modeling analysis uses version 5.0.2 of the Community 
Multiscale Air Quality (CMAQ) photochemical model, developed by the 
EPA. To prepare meteorological input for CMAQ, the modeling analysis 
uses the Weather and Research Forecasting model version 3.6 (WRF) from 
the National Center for Atmospheric Research. CMAQ and WRF are both 
recognized in the Modeling Guidance as technically sound, state-of-the-
art models. The areal extent and the horizontal and vertical resolution 
used in these models are adequate for modeling West Mojave Desert 
ozone.
    The SCAQMD assessed the performance of the WRF meteorological model 
through a series of simulations, and the SCAQMD concluded that the 
daily WRF simulation for 2012 provided representative meteorological 
fields that characterized the observed conditions well. The SCAQMD's 
conclusions are supported by hourly time series graphs of wind speed, 
direction, and temperature.\86\
---------------------------------------------------------------------------

    \86\ Attachment 1 (``WRF Model Performance Time Series''), 
Chapter 3 (``Meteorological Modeling and Sensitivity Analyses''), 
Appendix V (``Modeling and Attainment Demonstration'') of the 2016 
SCAQMD AQMP.
---------------------------------------------------------------------------

    Ozone model performance statistics are described in Appendix D, 
``West Mojave Desert Community Multiscale Air Quality Model Performance 
Analysis,'' of both the AVAQMD and MDAQMD Attainment Plans, which 
include tables of statistics

[[Page 24818]]

recommended in the Modeling Guidance for 8-hour daily maximum ozone for 
the WMD. This section presents hourly time series, as well as density 
scatter plots and plots of bias against concentration. Note that 
because only relative changes are used from the modeling, the 
overprediction or underprediction of absolute ozone concentrations does 
not mean that future concentrations will be overestimated or 
underestimated.
    After model performance for the 2012 base case was accepted, the 
model was applied to develop RRFs for the attainment demonstration. 
This entailed running the model with the same meteorological inputs as 
before, but with adjusted emissions inventories to reflect the expected 
changes between 2012 and the 2026 attainment year. The base year or 
``reference year'' modeling inventory was the same as the inventory for 
the modeling base case. The 2026 inventory projects the base year into 
the future by including the effect of economic growth and emissions 
control measures. The set of 153 days from May 1 through September 30, 
2012, was simulated and analyzed to determine daily 8-hour average 
maximum ozone concentrations for the 2020 emissions inventory. To 
develop the RRFs for the 2008 ozone NAAQS, only the top 10 days were 
used.
    The Modeling Guidance addresses attainment demonstrations with 
ozone NAAQS based on 8-hour averages. For the 2008 ozone NAAQS, 
Appendix D of the 2016 WMD Attainment Plan includes the attainment test 
procedure consistent with the Modeling Guidance. The RRFs were 
calculated as the ratio of future to base year concentrations. The 
resulting RRFs were then applied to 2012 weighted base year design 
values \87\ for each monitor to arrive at a 2026 future year design 
value.\88\ The 2016 WMD Attainment Plan narrowly projects that the West 
Mojave Desert will reach modeled attainment in 2023, with the highest 
ozone design value of 0.0759 ppm at the Phelan monitor site (station 
number: 06-071-0012); this value demonstrates attainment of the 
corresponding 2008 ozone NAAQS of 0.075 ppm.\89\
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    \87\ The Modeling Guidance recommends that RRFs be applied to 
the average of three three-year design values centered on the base 
year, in this case the design values for 2010-2012, 2011-2013, and 
2012-2014. This amounts to a 5-year weighted average of individual 
year 4th-high concentrations, centered on the base year of 2012, and 
so is referred to as a weighted design value.
    \88\ Table 5 of Appendix A-1 of the CARB Staff Report.
    \89\ Appendix P of 40 CFR part 50 for a discussion of reporting 
and handling procedures for the primary and secondary ozone 
standards that discusses truncating the third digit to the right of 
the decimal place.
---------------------------------------------------------------------------

    Appendix B of the CARB Staff Report presents a WOE analysis with 
further discussion of the modeling for the area. The WOE analysis 
includes the following: An evaluation of ambient ozone trends; 
precursor emissions trends for the region (i.e., the South Coast Air 
Basin, San Joaquin Valley, and the WMD); an evaluation of diurnal ozone 
monitoring trends; and a conceptual model that describes the conditions 
that create the exceedances of the 2008 ozone NAAQS. These evaluations 
complement the photochemical modeling analysis for the area and show 
that the area's timely attainment is dependent on continuing future 
reductions from implementation of control measures in neighboring 
upwind nonattainment areas. The WOE analysis concludes that, based on 
these upwind reductions from neighboring nonattainment areas, the WMD 
will attain the 2008 ozone standard by 2026.\90\
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    \90\ Appendix B, CARB Staff Report, B-30. The TSD for this 
action includes additional discussion of the modeled attainment 
demonstration and WOE analysis that support this conclusion.
---------------------------------------------------------------------------

    Finally, Appendix D of each of the Districts' Attainment Plans 
includes an unmonitored area analysis for the 2008 ozone NAAQS to 
assess the attainment status of locations other than monitoring sites. 
The unmonitored area analysis in the 2016 WMD Attainment Plan shows 
concentrations below the 2008 ozone NAAQS for all locations.\91\
---------------------------------------------------------------------------

    \91\ Figure 3: 2023 Predicted 8-hr Ozone Design Values, Appendix 
D, of both districts Attainment Plans.
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b. Control Strategy
    The control strategy for attainment of the 2008 ozone NAAQS in the 
WMD relies on timely attainment in 2023 of the 1997 ozone NAAQS in the 
upwind Los Angeles-South Coast Air Basin,\92\ which is the same year 
the WMD model shows attainment. The attainment plan for the 2008 ozone 
NAAQS for the South Coast Air Basin, which has been previously approved 
by the EPA, projects a 277 tpd reduction in NOX and a 121 
tpd reduction in VOC from 2012 base year emissions (522 tpd for 
NOX and 500 tpd for VOC).\93\ In addition, the 2008 ozone 
attainment plan for the San Joaquin Valley, which has also been 
previously approved by the EPA, projects a 214.6 tpd reduction of 
NOX and 34.4 tpd reduction of VOC in 2023, from 2012 base 
year emissions (339.6 tpd for NOX and 337.3 tpd for VOC in 
2011).\94\ Both upwind areas continue to show emission reductions 
through 2026 and beyond.
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    \92\ Appendix B, CARB Staff Report, B-2.
    \93\ Approval of Air Quality Implementation Plans; California; 
South Coast Air Basin; 1-Hour and 8-Hour Ozone Nonattainment Area 
Requirements, Proposed Rule, 84 FR 28132 (June 17, 2019). EPA 
finalized approval of the South Coast plan for the 2008 ozone NAAQS 
at 84 FR 52005 (October 1, 2019).
    \94\ Air Quality State Implementation Plans; Approvals and 
Promulgations: Clean Air Plans; 2008 8-Hour Ozone Nonattainment Area 
Requirements; San Joaquin Valley, California, Proposed Rule 83 FR 
61346 (November 28, 2018). EPA finalized approval of the San Joaquin 
Valley plan for the 2008 ozone NAAQS at 84 FR 3302 (February 12, 
2018).
---------------------------------------------------------------------------

    Within the WMD, the control strategy for attainment of the 2008 
ozone NAAQS in the 2016 WMD Attainment Plan relies primarily on 
emissions reductions from baseline (i.e., already-adopted) measures. 
These baseline control measures include the Districts' stationary 
source rules,\95\ and CARB's mobile source and consumer product rules 
adopted through 2016, as listed in Appendix F of the 2016 WMD 
Attainment Plan, ``CARB Adopted Mobile Source Programs.'' The 
attainment demonstration and base year emissions inventory use a 2012 
base year (101.09 tpd of NOX and 43.69 tpd of VOC), and 
consistent with South Coast II, the RFP demonstration relies on a 2011 
baseline year.\96\ The attainment year emissions estimate for the 
attainment demonstration is the same throughout the 2016 WMD Attainment 
Plan and 2018 SIP Update (68.5 tpd of NOX and 40.5 tpd of 
VOC) and represents a 30.3 percent NOX reduction and a 13.4 
percent VOC reduction from the 2012 emissions inventory base year 
emissions.
---------------------------------------------------------------------------

    \95\ Technical Support Document: Clean Air Plans; 2008 8-Hour 
Ozone Nonattainment Area Requirements; West Mojave Desert, 
California, EPA-R09-OAR-2020-0254, Tables 1 and 2.
    \96\ The modeling base year emissions were taken from Table 1 
and Appendix A of the AVAQMD and MDAQMD Attainment Plans. The CARB 
Staff Report notes 2012 base year emissions from the Districts' 
plans were average day emissions, i.e., averaged over the entire 
year, rather than average summer day emissions, which are included 
in Appendix A of the CARB Staff Report and were submitted as the 
2012 base year emissions.
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c. Attainment Demonstration
    Chapter 4 of the Districts' Attainment Plans describes the 
attainment demonstration in general terms, including photochemical 
modeling results. Chapter 4 references Appendix V of the SCAQMD 2016 
AQMP, which provides information on the modeling protocol. Appendix D 
of the District's Attainment Plans contains model results and 
performance for the WMD. The WOE analysis in Appendix B to the CARB 
Staff Report includes additional supporting information to complement 
the photochemical modeling and to provide context for this attainment

[[Page 24819]]

demonstration, such as ambient ozone data, a conceptual model of ozone 
formation, anthropogenic emission trends, ozone trends, and a 
discussion of the attainment projections. Baseline measures are 
expected to reduce 2012 base year emissions of NOX by 30.7 
percent and VOC emissions by 13 percent by 2026, and to attain the 2008 
ozone NAAQS in the WMD by 2023, three years ahead of the outermost 
attainment year, 2026.
3. The EPA's Review of the State's Submission
a. Photochemical Modeling
    The EPA has reviewed the modeling platform and agrees that the CMAQ 
(version 5.0.2) modeling platform, and the WRF (version 3.6.1) 
meteorological fields are appropriate for the ozone attainment 
demonstration. After review, the EPA is satisfied that the 
meteorological model, WRF, performed adequately. The diurnal variation 
of temperature, humidity and surface wind are well represented by WRF. 
The EPA has also reviewed the time series, scatter plots, and ozone 
performance, and determined that overall, the CMAQ photochemical 
modeling performance for ozone is acceptable.
    We are proposing to find the air quality modeling adequate to 
support the attainment demonstrations for the 2008 ozone NAAQS, based 
on reasonable meteorological and ozone modeling performance, supported 
by the weight of evidence analyses.
b. Control Strategy
    Based on our review of the emissions inventory documentation in the 
CARB Staff Report, we find that CARB and the Districts have used the 
most recent planning and activity assumptions, emissions models, and 
methodologies to estimate the effect of the control strategy on the 
baseline and milestone year emissions inventories. The 2016 WMD 
Attainment Plan relies on state and locally adopted baseline control 
measures, i.e., already-adopted control measures, to achieve the 
emissions reductions needed to attain the 2008 ozone NAAQS. The 
baseline measures are approved into the SIP and, as such, are fully 
creditable within the attainment demonstration analysis. Accordingly, 
we propose to find that the emissions reductions that are relied on for 
attainment are creditable and sufficient to provide for attainment.
c. Attainment Demonstration
    Based on our review of the 2016 WMD Attainment Plan and our 
proposed findings that the photochemical modeling and control strategy 
are acceptable and demonstrate attainment by July 20, 2027, we propose 
to approve the attainment demonstration for the 2008 ozone NAAQS in the 
2016 WMD Attainment Plan as meeting the requirements of CAA section 
182(c)(2)(A) and 40 CFR 51.1108. The Districts' Attainment Plans and 
the WOE in the CARB Staff Report demonstrate that the ozone design 
value in the WMD will meet the 0.075 ppm standard by 2026, and 
therefore will meet the attainment date of July 20, 2027, for the 2008 
ozone standard. While the submitted modeling projects that attainment 
is possible in advance of the 2026 deadline, the EPA is relying on the 
modeling, additional information provided in the WOE, and current ozone 
trends, to conclude that the WMD will attain the 2008 ozone NAAQS by 
2026, consistent with the outermost attainment date of July 20, 2027. 
See the TSD for additional information.

E. Rate of Progress Plan and Reasonable Further Progress Demonstration

1. Statutory and Regulatory Requirements
    Requirements for RFP are specified in CAA sections 172(c)(2), 
182(b)(1), and 182(c)(2)(B). CAA section 172(c)(2) requires that plans 
for nonattainment areas provide for RFP, which is defined at CAA 
section 171(1) as such annual incremental reductions in emissions of 
the relevant air pollutant as are required under part D, ``Plan 
Requirements for Nonattainment Areas,'' or may reasonably be required 
by the EPA for the purpose of ensuring attainment of the applicable 
NAAQS by the applicable date. CAA section 182(b)(1) specifically 
requires that ozone nonattainment areas that are classified as 
``Moderate'' or above demonstrate a 15 percent reduction in VOC between 
the years of 1990 and 1996. The EPA has typically referred to section 
182(b)(1) as the rate of progress (ROP) requirement. For ozone 
nonattainment areas classified as Serious or higher, section 
182(c)(2)(B) requires reductions averaged over each consecutive 3-year 
period beginning 6 years after the baseline year until the attainment 
date of at least 3 percent of baseline emissions per year. CAA section 
182(c)(2)(B)(ii) allows an amount less than 3 percent of such baseline 
emissions each year if the state demonstrates to the EPA that the plan 
includes all measures that can feasibly be implemented in the area in 
light of technological achievability.
    The 2008 Ozone SRR considers areas classified Moderate or higher to 
have met the ROP requirements of CAA section 182(b)(1) if the area has 
a fully approved 15 percent ROP plan for the 1-hour or 1997 8-hour 
ozone standards, provided the boundaries of the ozone nonattainment 
areas are the same.\97\ For such areas, the RFP requirements of CAA 
section 172(c)(2) require areas classified as Moderate to provide a 15 
percent emission reduction of ozone precursors within 6 years of the 
baseline year. Areas classified as Serious or higher must meet the RFP 
requirements of CAA section 182(c)(2)(B) by providing an 18 percent 
reduction of ozone precursors in the first 6-year period, and an 
average ozone precursor emission reduction of 3 percent per year for 
all remaining 3-year periods thereafter.\98\ Under CAA 182(c)(2)(C), a 
state may substitute NOX emissions reductions for VOC 
emissions reductions.
---------------------------------------------------------------------------

    \97\ 80 FR 12264, 12271 (March 6, 2015).
    \98\ Id.
---------------------------------------------------------------------------

    Except as specifically provided in CAA section 182(b)(1)(C), 
emission reductions from all SIP-approved, federally promulgated, or 
otherwise SIP-creditable measures that occur after the baseline are 
creditable for purposes of demonstrating that the RFP targets are met. 
Because the EPA has determined that the passage of time has caused the 
effect of certain exclusions to be de minimis, the RFP demonstration is 
no longer required to calculate and specifically exclude reductions 
from measures related to motor vehicle exhaust or evaporative emissions 
promulgated by January 1, 1990; regulations concerning Reid vapor 
pressure promulgated by November 15, 1990; measures to correct previous 
RACT requirements; and measures required to correct previous vehicle 
inspection and maintenance (I/M) programs.\99\
---------------------------------------------------------------------------

    \99\ 40 CFR 51.1110(a)(7).
---------------------------------------------------------------------------

    The 2008 Ozone SRR requires the RFP baseline year to be the most 
recent calendar year for which a complete triennial inventory is 
required to be submitted to the EPA (i.e., 2011). As discussed above, 
the 2008 Ozone SRR provided states with the opportunity to use an 
alternative baseline year for RFP,\100\ but this provision was vacated 
by the D.C. Circuit in the South Coast II decision.
---------------------------------------------------------------------------

    \100\ 40 CFR 51.1110(b).
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The 2016 WMD Attainment Plan addresses the 15 percent ROP 
requirement by noting that the EPA had proposed approval of the 15 
percent ROP plan for the 1997 ozone NAAQS for the WMD, and that the 
1997 ozone nonattainment area covers the entire

[[Page 24820]]

nonattainment area for the 2008 ozone standards.\101\ The EPA approved 
the 15 percent ROP demonstration for the 1997 ozone NAAQS, effective 
July 24, 2017.\102\
---------------------------------------------------------------------------

    \101\ Chapter 3 of both Districts' Attainment Plans.
    \102\ 82 FR 28560 (June 23, 2017).
---------------------------------------------------------------------------

    With respect to the RFP demonstration requirement, the 2016 WMD 
Attainment Plan includes an RFP demonstration derived from a 2012 RFP 
baseline year.\103\ In response to the South Coast II decision, CARB 
developed the 2018 SIP Update, which includes a section that replaces 
the RFP portion of the 2016 WMD Attainment Plan with an updated RFP 
demonstration based on a 2011 RFP baseline year.\104\ To develop the 
2011 RFP baseline inventory, CARB relied on actual emissions reported 
from industrial point sources for year 2011. For emissions from smaller 
stationary sources and area sources, CARB backcast emissions from 2012 
to 2011 using the same growth and control factors as were used for the 
2016 WMD Attainment Plan. To develop the emissions inventories for the 
2017, 2020 and 2023 RFP milestone years, CARB also relied upon the same 
growth and control factors as the 2016 WMD Attainment Plan. Therefore, 
the emissions estimates for the attainment year, 2026, are consistent 
in both the 2018 SIP Update and the 2016 WMD Attainment Plan.
---------------------------------------------------------------------------

    \103\ Chapter 3 of both Districts' Attainment Plans.
    \104\ Chapter VI of the 2018 SIP Update.
---------------------------------------------------------------------------

    Documentation for the WMD RFP baseline and milestone emissions 
inventories is found in the 2018 SIP Update on pages 36-37 and in 
Appendix A of the 2018 SIP Update on pages A-19 through A-22. The RFP 
baseline emissions inventories reflect rules identified in Table 5 of 
the CARB Staff Report.
    Table 2 provides a summary of CARB's emissions estimates in tpd for 
VOC and NOX for the 2011 RFP baseline year, the 2017, 2020, 
2023 RFP milestone years, and the 2026 RFP milestone/attainment year, 
evaluated relative to the percentage reductions necessary to 
demonstrate RFP.

                             Table 2--WMD RFP Demonstration for the 2008 Ozone NAAQS
                                   [Summer planning inventory, tpd or percent]
----------------------------------------------------------------------------------------------------------------
                                       2011            2017            2020            2023            2026
----------------------------------------------------------------------------------------------------------------
                                                      VOCs
----------------------------------------------------------------------------------------------------------------
Baseline VOC....................            48.7            41.5            40.4            40.4            40.5
Transportation conformity safety  ..............               0               0               0             0.2
 margin.........................
Baseline VOC + safety margin....            48.7            41.5            40.4            40.4            40.7
Required % change since 2011....  ..............             18%             27%             36%             45%
Target VOC level................  ..............            40.0            35.6            31.2            26.8
Apparent shortfall/surplus, tpd.  ..............            -1.5            -4.8            -9.2           -13.9
Apparent shortfall ( - )/surplus  ..............           -3.1%           -9.9%          -18.8%          -28.4%
 ( + ) in VOC...................
VOC shortfall previously          ..............               0            3.1%            9.9%           18.8%
 provided by NOX substitution, %
Actual VOC shortfall ( - )/       ..............           -3.1%           -6.8%           -8.9%           -9.6%
 surplus ( + ), %...............
----------------------------------------------------------------------------------------------------------------
                                                       NO
----------------------------------------------------------------------------------------------------------------
Baseline NOX....................            98.4            84.5            79.8            72.1            68.5
Transportation conformity safety               0               0               0               0             0.4
 margin.........................
Baseline NOX + safety margin....            98.4            84.5            79.8            72.1            68.9
Change in NOX since 2011, tpd...  ..............            13.8            18.6            26.2            29.4
Change in NOX since 2011, %.....  ..............           14.1%           18.9%           26.7%           29.9%
NOX reductions used for VOC       ..............               0            3.1%            9.9%           18.8%
 substitution through last
 milestone year, %..............
NOX reductions since 2011         ..............           14.1%           15.8%           16.7%           11.1%
 available for VOC substitution
 in this milestone year, %......
NOX reductions since 2011         ..............            3.1%            6.8%            8.9%            9.6%
 available for VOC substitution
 in this milestone year, %......
NOX reductions since 2011         ..............           10.9%            9.0%            7.9%            1.5%
 surplus after meeting VOC
 substitution needs in this
 milestone year, %..............
Total shortfall for RFP.........  ..............              0%              0%              0%              0%
RFP met?........................  ..............             Yes             Yes             Yes             Yes
----------------------------------------------------------------------------------------------------------------
Source: Table VI-2, 2018 SIP Update.

    The revised RFP demonstration calculates future year VOC targets 
from the 2011 baseline, consistent with CAA 182(c)(2)(B)(i), which 
requires reductions of ``at least 3 percent of baseline emissions each 
year,'' and it substitutes NOX reductions for VOC reductions 
beginning in milestone year 2017 to meet VOC emission targets. 
NOX substitution is permitted under EPA regulations at 40 
CFR 51.1110(a)(2)(i)(C) and 40 CFR 51.1110(a)(2)(ii)(B). As stated in 
the WOE in the CARB Staff Report, ``given Western Mojave's downwind 
location from the only two extreme ozone nonattainment areas in the 
country, it is expected that ozone formation would be limited by 
available NOX emissions,'' meaning that NOX 
reductions would be more effective at reducing ozone concentrations 
than VOC reductions. For the WMD, CARB concluded that the revised RFP 
demonstration meets the applicable requirements for each milestone year 
as well as the attainment year.
3. The EPA's Review of the State's Submission
    Consistent with the 2008 Ozone SRR, the EPA's final approval of the 
15 percent ROP demonstration for the 1997 ozone NAAQS fulfills the 
requirements of CAA section 182(b)(1) for WMD for the 2008 ozone 
NAAQS.\105\
---------------------------------------------------------------------------

    \105\ 82 FR 13086 (March 9, 2017).
---------------------------------------------------------------------------

    With respect to the RFP demonstration requirement, based on

[[Page 24821]]

our review of the emissions inventory documentation in the 2018 SIP 
Update, we find that CARB and the District have used the most recent 
planning and activity assumptions, emissions models, and methodologies 
in developing the RFP baseline and milestone year emissions 
inventories. We have also reviewed and verified the calculations in 
Table VI-3 of the 2018 SIP Update. Furthermore, we find that 
NOX emission reductions are as effective as VOC emission 
reductions in reducing levels of ozone within the Western Mojave 
Desert.\106\ For these reasons, we have determined that the 2018 SIP 
Update demonstrates RFP in the 2017, 2020, and 2023 milestone years as 
well as the 2026 milestone/attainment year, consistent with applicable 
CAA requirements and EPA guidance. Therefore, we propose to approve the 
RFP demonstration for the WMD for the 2008 ozone NAAQS under sections 
172(c)(2) and 182(c)(2)(B) of the CAA and 40 CFR 51.1110(a)(2)(ii).
---------------------------------------------------------------------------

    \106\ Additional evaluation of this matter is discussed in 
Section V of the TSD supporting this notice.
---------------------------------------------------------------------------

F. Transportation Control Strategies and Measures To Offset Emissions 
Increases From Vehicle Miles Traveled

1. Statutory and Regulatory Requirements
    Section 182(d)(1)(A) of the Act requires a state to submit a 
revision for each area classified as Serious or above that identifies 
and adopts specific enforceable transportation control strategies 
(TCSs) and transportation control measures (TCMs) to offset any growth 
in emissions from growth in vehicle miles traveled (VMT) or number of 
vehicle trips in such area.\107\ Herein, we use ``VMT'' to refer to 
vehicle miles traveled and refer to the related SIP requirement as the 
``VMT emissions offset requirement.'' In addition, we refer to the SIP 
revision intended to demonstrate compliance with the VMT emissions 
offset requirement as the ``VMT emissions offset demonstration.''
---------------------------------------------------------------------------

    \107\ CAA section 182(d)(1)(A) includes three separate elements. 
In short, under section 182(d)(1)(A), states are required to adopt 
transportation control strategies and measures (1) to offset growth 
in emissions from growth in VMT, and, (2) in combination with other 
emission reduction requirements, to demonstrate RFP, and (3) to 
demonstrate attainment. For more information on the EPA's 
interpretation of the three elements of section 182(d)(1)(A), see 77 
FR 58067, at 58068 (September 19, 2012) (proposed withdrawal of 
approval of South Coast VMT emissions offset demonstrations).
---------------------------------------------------------------------------

    In Association of Irritated Residents v. EPA, the United States 
Court of Appeals for the Ninth Circuit (``Ninth Circuit'') ruled that 
additional TCMs are required whenever vehicle emissions are projected 
to be higher than they would have been had VMT not increased, even when 
aggregate vehicle emissions are actually decreasing.\108\ In response 
to the Ninth Circuit's decision, the EPA issued a memorandum titled 
``Guidance on Implementing Clean Air Act Section 182(d)(1)(A): 
Transportation Control Measures and Transportation Control Strategies 
to Offset Growth in Emissions Due to Growth in Vehicle Miles 
Travelled'' (``August 2012 Guidance'').\109\
---------------------------------------------------------------------------

    \108\ Association of Irritated Residents v. EPA, 632 F.3d. 584, 
at 596-597 (9th Cir. 2011), reprinted as amended on January 27, 
2012, 686 F.3d 668, further amended February 13, 2012 (``Association 
of Irritated Residents'').
    \109\ Memorandum from Karl Simon, Director, Transportation and 
Climate Division, Office of Transportation and Air Quality, to Carl 
Edlund, Director, Multimedia Planning and Permitting Division, EPA 
Region VI, and Deborah Jordan, Director, Air Division, EPA Region 
IX, August 30, 2012.
---------------------------------------------------------------------------

    The August 2012 Guidance discusses the meaning of TCSs and TCMs and 
recommends that both TCSs and TCMs be included in the calculations made 
for the purpose of determining the degree to which any hypothetical 
growth in emissions due to growth in VMT should be offset. Generally, 
TCSs encompass many types of controls (including, for example, motor 
vehicle emissions limitations, I/M programs, alternative fuel programs, 
other technology-based measures, and TCMs) that would fit within the 
regulatory definition of ``control strategy.'' \110\ Such measures 
include, but are not limited to, those listed in CAA section 108(f). 
TCM is defined at 40 CFR 51.100(r) as meaning ``any measure that is 
directed toward reducing emissions of air pollutants from 
transportation sources,'' including, but not limited to, those listed 
in section 108(f) of the CAA. TCMs generally refer to programs intended 
to reduce VMT, the number of vehicle trips, or traffic congestion, 
including, e.g., programs for improved public transit, designation of 
certain lanes for passenger buses and high-occupancy vehicles, and trip 
reduction ordinances.
---------------------------------------------------------------------------

    \110\ See, e.g., 40 CFR 51.100(n). TCMs are defined at 40 CFR 
51.100(r) as meaning any measure that is directed toward reducing 
emissions of air pollutants from transportation sources.
---------------------------------------------------------------------------

    The August 2012 Guidance explains how states may demonstrate that 
the VMT emissions offset requirement is satisfied in conformance with 
the Ninth Circuit's ruling. The August 2012 Guidance recommends that 
states estimate emissions for the nonattainment area's base year and 
attainment year. One emissions inventory is developed for the base 
year, and three different emissions inventory scenarios are developed 
for the attainment year. For the attainment year, the state would 
present three emissions estimates, two of which would represent 
hypothetical emissions scenarios that would provide the basis to 
identify the growth in emissions due solely to the growth in VMT, and 
one that would represent projected actual motor vehicle emissions after 
fully accounting for projected VMT growth and offsetting emissions 
reductions obtained by all creditable TCSs and TCMs. See the August 
2012 Guidance for specific details on how states might conduct the 
calculations.
    The base year on-road VOC emissions should be calculated using VMT 
in that year and should reflect all enforceable TCSs and TCMs in place 
in the base year. This would include vehicle emissions standards, state 
and local control programs such as I/M programs or fuel rules, and any 
additional implemented TCSs and TCMs that were already required by or 
credited in the SIP as of that base year.
    The first of the emissions calculations for the attainment year 
would be based on the projected VMT and trips for that year and assume 
that no new TCSs or TCMs beyond those already credited in the base year 
inventory have been put in place since the base year. This calculation 
demonstrates how emissions would hypothetically change if no new TCSs 
or TCMs were implemented, and VMT and trips were allowed to grow at the 
projected rate from the base year. This estimate would show the 
potential for an increase in emissions due solely to growth in VMT and 
trips. This represents a ``no action'' scenario. Emissions in the 
attainment year in this scenario may be lower than those in the base 
year due to fleet turnover; however, if VMT and/or numbers of vehicle 
trips are projected to increase in the attainment year, emissions would 
still likely be higher than if VMT had held constant.
    The second of the attainment year's emissions calculations would 
assume that no new TCSs or TCMs beyond those already credited have been 
put in place since the base year, but it would also assume that there 
was no growth in VMT and trips between the base year and attainment 
year. This estimate reflects the hypothetical emissions level that 
would have occurred if no further TCMs or TCSs had been put in place 
and if VMT and trip levels had held constant since the base year. Like 
the ``no action'' attainment year estimate described above, emissions 
in the attainment year may be lower than those in the base year due to 
fleet turnover, but in this case emissions would not be

[[Page 24822]]

influenced by any growth in VMT or trips. This emissions estimate would 
reflect a ceiling on the attainment emissions that should be allowed to 
occur under the statute as interpreted by the Ninth Circuit because it 
shows what would happen under a scenario in which no offsetting TCSs or 
TCMs have yet been put in place and VMT and trips are held constant 
during the period from the area's base year to its attainment year. 
This represents a ``VMT offset ceiling'' scenario. These two 
hypothetical status quo estimates are necessary steps in identifying 
the target level of emissions from which states determine whether 
further TCMs or TCSs, beyond those that have been adopted and 
implemented in reality, would need to be adopted and implemented in 
order to fully offset any increase in emissions due solely to VMT and 
trips identified in the ``no action'' scenario.
    Finally, the state would present the emissions that are actually 
expected to occur in the area's attainment year after taking into 
account reductions from all enforceable TCSs and TCMs put in place 
after the baseline year. This estimate would be based on the VMT and 
trip levels expected to occur in the attainment year (i.e., the VMT and 
trip levels from the first estimate) and all of the TCSs and TCMs 
expected to be in place and for which the SIP will take credit in the 
area's attainment year, including any TCMs and TCSs put in place since 
the base year. This represents the ``projected actual'' attainment year 
scenario. If this emissions estimate is less than or equal to the 
emissions ceiling that was established in the second of the attainment 
year calculations, the TCSs or TCMs for the attainment year would be 
sufficient to fully offset the identified hypothetical growth in 
emissions.
    Alternatively, if the estimated projected actual attainment year 
emissions are still greater than the ceiling that was established in 
the second of the attainment year emissions calculations, even after 
accounting for post-baseline year TCSs and TCMs, the state would need 
to adopt and implement additional TCSs or TCMs to further offset the 
growth in emissions. The additional TCSs or TCMs would need to bring 
the actual emissions down to at least the ``had VMT and trips held 
constant'' ceiling estimated in the second of the attainment year 
calculations, in order to meet the VMT offset requirement of section 
182(d)(1)(A) as interpreted by the Ninth Circuit.
2. Summary of the State's Submission
    The VMT emissions offset demonstration for the WMD for the 2008 
ozone NAAQS is contained in Chapter 3 of the Districts' Attainment 
Plans.\111\ For the VMT emissions offset demonstration, CARB used 
EMFAC2014, the latest EPA-approved motor vehicle emissions model for 
California available at the time the 2016 WMD Attainment Plan was 
developed.\112\ The EMFAC2014 model estimates the on-road emissions 
from two combustion processes (i.e., running exhaust and start exhaust) 
and four evaporative processes (i.e., hot soak, running losses, diurnal 
losses, and resting losses). The EMFAC2014 model combines trip-based 
VMT data from the regional transportation planning agency (i.e., SCAG), 
starts data based on household travel surveys, and vehicle population 
data from the California Department of Motor Vehicles. These sets of 
data are combined with corresponding emission rates to calculate 
emissions.
---------------------------------------------------------------------------

    \111\ AVAQMD Attainment Plan, 23, and MDAQMD Attainment Plan, 
25.
    \112\ On August 15, 2019, the EPA approved and announced the 
availability of EMFAC2017, the latest update to the EMFAC model for 
use by State and local governments to meet CAA requirements. See 84 
FR 41717.
---------------------------------------------------------------------------

    Emissions from running exhaust, start exhaust, hot soak, and 
running losses are a function of how much a vehicle is driven. 
Emissions from these processes are thus directly related to VMT and 
vehicle trips, and the analysis included these emissions in the 
calculations that provide the basis for the WMD VMT emissions offset 
demonstration. The analysis did not include emissions from resting loss 
and diurnal loss processes in the analysis because such emissions are 
related to vehicle population, not to VMT or vehicle trips, and thus 
are not part of ``any growth in emissions from growth in vehicle miles 
traveled or numbers of vehicle trips in such area'' under CAA section 
182(d)(1)(A).
    The WMD VMT emissions offset demonstration uses a 2012 base year. 
The base year for VMT emissions offset demonstration purposes should 
generally be the same base year used for nonattainment planning 
purposes. In section III.A of this document, the EPA is proposing to 
approve the 2012 base year inventory for the WMD for the purposes of 
the 2008 ozone NAAQS, and thus, the selection of 2012 as the base year 
for the WMD VMT emissions offset demonstration for the 2008 ozone NAAQS 
is appropriate.
    The WMD VMT emissions offset demonstration also includes the 
previously described three different attainment year scenarios (i.e., 
no action, VMT offset ceiling, and projected actual). The 2016 WMD 
Attainment Plan provides a demonstration of attainment of the 2008 
ozone NAAQS in the WMD by the applicable attainment date, based on the 
controlled 2026 emissions inventory. As described in section III.D of 
this document, the EPA is proposing to approve the attainment 
demonstration for the 2008 ozone NAAQS for the WMD, and thus, we find 
the selection of year 2026 as the attainment year for the VMT emissions 
offset demonstration for the 2008 ozone NAAQS to be acceptable.
    Table 3 summarizes the relevant distinguishing parameters for each 
of the emissions scenarios and shows CARB's corresponding VOC emissions 
estimates for the demonstration for the 2008 ozone NAAQS.

                                   Table 3--VMT Emissions Offset Inventory Scenarios and Results for 2008 Ozone NAAQS
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        VMT                           Starts                 Controls      VOC emissions
                                                         -----------------------------------------------------------------------------------------------
                        Scenario                                           1,000 miles/
                                                               Year             day            Year          1,000/day         Year             Tpd
--------------------------------------------------------------------------------------------------------------------------------------------------------
Base Year...............................................            2012          26,536            2012           4,470            2012            12.4
No Action...............................................            2026          34,724            2026           5,238            2012             6.5
VMT Offset Ceiling......................................            2012          26,536            2012           4,470            2012             5.3
Actual Projected........................................            2026          34,724            2026           5,238            2026             4.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: AVAQMD Attainment Plan, 23-27, and MDAQMD Attainment Plan, 26-29.

[[Page 24823]]

3. The EPA's Review of the State's Submission
    Based on our review of the WMD VMT emissions offset demonstration 
in the 2016 WMD Attainment Plan, we find CARB's analysis to be 
consistent with our August 2012 Guidance and consistent with the 
emissions and vehicle activity estimates provided by CARB in support of 
the 2016 AQMP. We agree that the TCSs and TCMs in place for the area 
are sufficient to offset the growth in emissions from growth in VMT and 
vehicle trips in the WMD for the purposes of the 2008 8-hour ozone 
standards. As such, we find that the WMD VMT emissions offset 
demonstration complies with the VMT emissions offset requirement in CAA 
section 182(d)(1)(A). Therefore, we propose approval of the WMD VMT 
emissions offset demonstration portion of the 2016 WMD Attainment Plan.

G. Contingency Measures

1. Statutory and Regulatory Requirements
    Under the CAA, SIPs for 8-hour ozone nonattainment areas classified 
under subpart 2 as Moderate or above must include contingency measures 
consistent with sections 172(c)(9) and 182(c)(9). Contingency measures 
are additional controls or measures to be implemented in the event an 
area fails to make RFP or to attain the NAAQS by the attainment date. 
The SIP should contain trigger mechanisms for the contingency measures, 
specify a schedule for implementation, and indicate that the measure 
will be implemented without significant further action by the state or 
the EPA.\113\
---------------------------------------------------------------------------

    \113\ 70 FR 71612 (November 29, 2005). See also 2008 Ozone SRR, 
80 FR 12264, 12285 (March 6, 2015).
---------------------------------------------------------------------------

    Neither the CAA nor the EPA's implementing regulations establish a 
specific level of emissions reductions that implementation of 
contingency measures must achieve, but the EPA's 2008 Ozone SRR 
reiterates the EPA's policy that contingency measures should generally 
provide for emissions reductions approximately equivalent to one year's 
worth progress, amounting to reductions of 3 percent of the baseline 
emissions inventory for the nonattainment area.\114\
---------------------------------------------------------------------------

    \114\ 80 FR 12264, 12285 (March 6, 2015).
---------------------------------------------------------------------------

    It has been the EPA's longstanding interpretation of CAA section 
172(c)(9) that states may meet the contingency measure requirement by 
relying on federal measures (e.g., federal mobile source measures based 
on the incremental turnover of the motor vehicle fleet each year) and 
local measures already scheduled for implementation that provide 
emissions reductions in excess of those needed to provide for RFP or 
expeditious attainment. The key is that the Act requires contingency 
measures to 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 a plan is being revised to meet 
the missed milestone or attainment date.
    The EPA has approved numerous SIPs under this interpretation--i.e., 
SIPs that use as contingency measures one or more federal or local 
measures that are in place and provide reductions in excess of the 
reductions required by the attainment demonstration or RFP plan,\115\ 
and there is case law supporting the EPA's interpretation in this 
regard.\116\ However, in Bahr v. EPA, the Ninth Circuit rejected the 
EPA's interpretation of CAA section 172(c)(9) as allowing for early 
implementation of contingency measures.\117\ The Ninth Circuit 
concluded that contingency measures must take effect at the time the 
area fails to make RFP or attain by the applicable attainment date, not 
before.\118\ The D.C. Circuit recently reached a similar conclusion 
regarding the contingency measure provisions in CAA sections 172(c)(9) 
and 182(c)(9), in Sierra Club v. EPA.\119\ Following these decisions, 
states cannot rely on early-implemented measures to comply with the 
contingency measure requirements under CAA section 172(c)(9) and 
182(c)(9).
---------------------------------------------------------------------------

    \115\ See, 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).
    \116\ See, 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).
    \117\ Bahr v. EPA, 836 F.3d at 1235-1237 (9th Cir. 2016) 
(``Bahr'').
    \118\ Id. at 1235-1237.
    \119\ Sierra Club v. EPA, 985 F.3d 1055 (D.C. Cir. 2021) 
(``Sierra Club'').
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The Districts and CARB had largely prepared the 2016 WMD Attainment 
Plan prior to the Bahr and Sierra Club decisions; therefore, the plan 
relies solely upon surplus emissions reductions from already 
implemented control measures in the RFP milestone years to demonstrate 
compliance with the RFP milestone contingency measures requirements of 
CAA sections 172(c)(9) and 182(c)(9).\120\ The plan also demonstrates 
compliance with the attainment contingency measures requirements using 
surplus emissions reductions (in the year after the attainment year), 
and separately identifies use of the State's enhanced I/M program as an 
attainment contingency measure.\121\
---------------------------------------------------------------------------

    \120\ AQAQMD Attainment Plan, 20; MDAQMD Attainment Plan, 22.
    \121\ Id. AQAQMD Attainment Plan, 18; MDAQMD Attainment Plan, 
20.
---------------------------------------------------------------------------

    In the 2018 SIP Update, CARB revised the RFP demonstration for the 
2008 ozone NAAQS for the WMD and recalculated the extent of surplus 
emission reductions in the milestone years. Consistent with the Bahr 
decision (and the later Sierra Club decision), the 2018 SIP Update does 
not rely on the surplus or incremental emissions reductions to comply 
with the contingency measures requirements of sections 172(c)(9) and 
182(c)(9) but instead documents the extent to which future baseline 
emissions would provide surplus emissions reductions beyond those 
required to meet applicable contingency measure requirements, to 
provide context for determining the magnitude of the contingency 
measures needed for the 2008 ozone NAAQS.
    The 2018 SIP Update identifies one year's worth of RFP as 
approximately 1.5 tpd of VOC. The 2018 SIP Update estimates surplus 
NOX reductions for RFP as ranging from approximately 10.7 
tpd in 2017 to 7.8 tpd in 2023, and estimates that implementation of 
the state control measures will result in an additional 0.2 tpd VOC and 
1.6 tpd of NOX emissions reductions occuring in the year 
after the attainment year.\122\
---------------------------------------------------------------------------

    \122\ 2018 SIP Update, Chapter VI, Tables VI-4, VI-5, and VI-6.
---------------------------------------------------------------------------

    In subsequent communications, CARB has clarified that the proposed 
contingency measure would involve implementation of enhanced I/M 
specifically in those areas of the WMD subject to MDAQMD jurisdiction 
that are currently subject only to basic I/M requirements.\123\ As 
described by the MDAQMD, within 30 days of a finding by the EPA that 
the WMD has either failed to meet an RFP milestone for the 2008 ozone 
NAAQS or failed to attain the 2008 ozone NAAQS by the

[[Page 24824]]

attainment deadline, the MDAQMD Executive Officer will transmit a 
formal letter to the California Bureau of Automotive Repair (BAR) 
requesting implementation of the enhanced I/M program throughout the 
entirety of the portion of the WMD that is subject to the District's 
jurisdiction. Upon receiving the District's letter, BAR would initiate 
the program and notify the relevant stakeholders of the updated 
requirements in the area. This procedure is described in section 
44003(c) of the California Health and Safety Code, and no additional 
regulations would need to be adopted.\124\ CARB estimates that 
implementation of the enhanced I/M program for this region will result 
in additional emissions reductions of 0.03 tpd of VOC and 0.04 tpd of 
NOX.\125\
---------------------------------------------------------------------------

    \123\ Email dated November 20, 2020, from Ariel Fideldy (CARB) 
to Tom Kelly (EPA), Subject: West Mojave Desert Contingency 
Measures.
    \124\ Letter dated March 29, 2021, from Brad Poiriez, Executive 
Officer, MDAQMD, to Richard Corey, Executive Officer, CARB. The EPA 
approved California Health and Safety Code section 44003(c) into the 
California SIP at 75 FR 38023 (July 1, 2010).
    \125\ Letter dated April 9, 2021, from Michael Benjamin, Chief, 
Air Quality Planning and Science Division, CARB, to Deborah Jordan, 
Acting Regional Administrator, EPA Region IX. CARB indicates that 
these figures represent conservative estimates of the potential 
emissions reductions that would result from implementation of the 
contingency measure, because they are derived from residential 
populations that may underrepresent the actual vehicle populations 
located within the zip codes currently subject to basic I/M. See 
Attachment A to letter dated April 9, 2021, from Michael Benjamin, 
Chief, Air Quality Planning and Science Division, CARB, to Deborah 
Jordan, Acting Regional Administrator, EPA Region IX.
---------------------------------------------------------------------------

    The MDAQMD has committed to submit a Board resolution further 
detailing the circumstances, timing, and procedure for implementing 
this contingency measure, within eleven months of the EPA's final 
conditional approval of the contingency measures element of the 2016 
WMD Attainment Plan.\126\ CARB, in turn, has committed to submit the 
Board resolution to the EPA for SIP approval within 12 months of the 
EPA's final conditional approval.\127\
---------------------------------------------------------------------------

    \126\ Letter dated March 29, 2021, from Brad Poiriez, Executive 
Officer, MDAQMD, to Richard Corey, Executive Officer, CARB.
    \127\ Letter dated April 9, 2021, from Michael Benjamin, Chief, 
Air Quality Planning and Science Division, CARB, to Deborah Jordan, 
Acting Regional Administrator, EPA Region IX.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    Sections 172(c)(9) and 182(c)(9) of the CAA require contingency 
measures to address potential failure to achieve RFP milestones or 
failure to attain the NAAQS by the applicable attainment date. To 
evaluate the contingency measure element of the 2016 WMD Attainment 
Plan, we find it useful to distinguish between contingency measures to 
address potential failure to achieve RFP milestones (``RFP contingency 
measures'') and contingency measures to address potential failure to 
attain the NAAQS (``attainment contingency measures'').
    With respect to the RFP contingency measure requirement, we have 
reviewed the surplus emissions estimates in each of the RFP milestone 
years, as shown in the 2018 SIP Update, and find that the calculations 
are correct. Therefore, we agree that the emission estimates from the 
2018 SIP Update provide surplus reductions well beyond those necessary 
to demonstrate RFP in the RFP milestone years. While such surplus 
emissions reductions in the RFP milestone years do not represent 
contingency measures themselves, we believe they are relevant in 
evaluating the adequacy of RFP contingency measures that are submitted 
(or will be submitted) to meet the requirements of sections 172(c)(9) 
and 182(c)(9).
    In this case, the MDAQMD and CARB have committed to develop, adopt, 
and submit a Board resolution further detailing the circumstances, 
timing, and procedure for implementing enhanced I/M requirements in the 
portion of the WMD that is currently subject to basic I/M, should the 
WMD fail to meet an RFP milestone. The specific commitment of the 
MDAQMD upon an RFP milestone failure (i.e., changing from basic to 
enhanced I/M) complies with the requirements in CAA sections 172(c)(9) 
and 182(c)(9) because it would be undertaken if the area fails to meet 
an RFP milestone and would take effect without further significant 
action by the District, the State, or the EPA.\128\
---------------------------------------------------------------------------

    \128\ Section 182(c)(3) of the CAA requires states with ozone 
nonattainment areas classified under subpart 2 as Serious or above 
to implement an enhanced motor vehicle I/M program in each urbanized 
area within the nonattainment area. Section 182(c)(3) further 
explains that urbanized areas are ``defined by the Bureau of the 
Census, with a 1980 population of 200,000 or more.'' Because parts 
of the MDAQMD within the WMD were not considered urbanized areas in 
1980, only part of the WMD is subject to enhanced I/M. All of the 
area under the jurisdiction of the AVAQMD is subject to enhanced I/
M.
---------------------------------------------------------------------------

    To assess the adequacy of the RFP contingency measure (once adopted 
and submitted), we next consider the magnitude of emissions reductions 
the measure would provide if triggered. Neither the CAA nor the EPA's 
implementing regulations for the ozone NAAQS establish a specific 
amount of emissions reductions that implementation of contingency 
measures must achieve, but we generally expect that contingency 
measures should provide for emissions reductions equivalent to 
approximately one year's worth of RFP, which, for ozone, amounts to 
reductions of 3 percent of the baseline emissions inventory for the 
nonattainment area. For the 2008 ozone NAAQS in the WMD, one year's 
worth of RFP is approximately 1.5 tpd of VOC, or 3.0 tpd of 
NOX reductions, or a combination of the two calculated on a 
percentage basis.\129\ In its commitment letter, CARB conservatively 
estimates the potential additional emissions reductions from the 
contingency measure commitments at 0.03 tpd of VOC and 0.04 tpd of 
NOX. While these amounts collectively reflect less than one 
year's worth of RFP, the 2018 SIP Update provides the larger SIP 
planning context with which to judge the adequacy of the to-be-
submitted District contingency measures, by calculating the surplus 
emissions reductions estimated to be achieved in the RFP milestone 
years. The estimates of surplus NOX reductions range from 
10.7 to 7.8 tpd, depending on the RFP year, which represents more than 
twice one year's worth of progress (3.0 tpd of NOX).\130\ 
The surplus reflects already implemented regulations and is primarily 
the result of vehicle turnover, which refers to the ongoing replacement 
by individuals, companies, and government agencies of older, more 
polluting vehicles and engines with newer vehicles and engines. In 
light of these surplus NOX emissions reductions in the RFP 
milestone years, the emissions reductions from the committed 
contingency measure are adequate to meet the contingency measure 
requirements of the CAA with respect to RFP milestones.
---------------------------------------------------------------------------

    \129\ The 2011 baseline for VOC and NOX is 48.7 tpd 
and 98.4 tpd, respectively, as shown in table VI-1 of the 2018 SIP 
Update. Three percent of these baselines is 1.5 tpd of VOC and 3.0 
tpd of NOX.
    \130\ 2018 SIP Update, Table VI-5.
---------------------------------------------------------------------------

    For attainment contingency measure purposes, we evaluate the 
emissions reductions from the District's contingency measures in the 
context of the expected reduction in emissions within the WMD in the 
year following the attainment year, relative to those occurring in the 
attainment year. In 2027, VOC and NOX emissions for the WMD 
are expected to be approximately 0.2 and 1.6 tpd, respectively, lower 
than the emissions in 2026. Considered together, the continuing 
reductions from already-implemented measures and the emissions 
reductions from the MDAQMD's contingency measure provide for emissions 
reductions near to, but below, one year's worth of progress.\131\ 
Therefore, we find that the

[[Page 24825]]

contingency measures described in the MDAQMD's and CARB's commitment 
letters would provide sufficient emissions reductions to satisfy the 
attainment contingency measures requirement, even though reductions 
from the measures would be lower than one year's worth of RFP.
---------------------------------------------------------------------------

    \131\ Combined reductions (0.23 tpd VOC and 1.64 tpd 
NOX) represent 70 percent of one year's RFP (15.3 percent 
of 1.5 tpd VOC; 54.7 percent of 3.0 tpd NOX). Further 
emissions reductions are projected to occur in upwind areas in the 
year following the attainment year (see, e.g., 2016 AQMP, Chapter 
3), and we anticipate that these reductions will drive additional 
reductions in ozone concentrations in the WMD in this period, 
consistent with the strong influence of upwind emissions on 
nonattainment in the WMD.
---------------------------------------------------------------------------

    For these reasons, we propose to conditionally approve the 
contingency measures element of the 2016 WMD attainment plan, as 
supplemented by the commitment from the MDAQMD and CARB to adopt and 
submit an MDAQMD Board resolution detailing the circumstances, timing, 
and procedure for implementing the contingency measure requirements of 
CAA sections 172(c)(9) and 182(c)(9). Our proposed approval is 
conditional because it relies upon specific commitments from MDAQMD and 
CARB. Conditional approvals are authorized under CAA section 110(k)(4).

H. Motor Vehicle Emissions Budgets for Transportation Conformity

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 expeditious 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 (MPO) 
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 emissions 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, if the plan demonstrates attainment, the attainment 
year.\132\
---------------------------------------------------------------------------

    \132\ 40 CFR 93.102(b)(2)(i).
---------------------------------------------------------------------------

    For motor vehicle emissions budgets to be approvable, they must 
meet, at a minimum, the EPA's adequacy criteria (40 CFR 93.118(e)(4) 
and (5)) and be approvable under all pertinent SIP requirements. To 
meet these requirements, the MVEBs must be consistent with the 
approvable attainment and RFP demonstrations and reflect all of the 
motor vehicle control measures contained in the attainment and RFP 
demonstrations.\133\ Budgets may include a safety margin representing 
the difference between projected emissions and the total amount of 
emissions estimated to satisfy any requirements for attainment or RFP.
---------------------------------------------------------------------------

    \133\ 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 MVEB consists of 
three basic steps: (1) Providing public notification of a SIP 
submission; (2) providing the public the opportunity to comment on the 
MVEB during a public comment period; and, (3) making a finding of 
adequacy or inadequacy.\134\
---------------------------------------------------------------------------

    \134\ 40 CFR 93.118.
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The 2016 WMD Attainment Plan includes budgets for the 2018, 2021, 
and 2024 RFP milestone years, and a 2026 attainment year. The budgets 
for 2018, 2021, and 2024 were derived from the 2012 RFP baseline year 
and the associated RFP milestone years. These budgets are affected by 
the South Coast II decision vacating the alternative baseline year 
provision, and therefore, the EPA has not previously acted on the 
budgets.
    The 2018 SIP Update revised the RFP demonstration consistent with 
the South Coast II decision (i.e., by using a 2011 RFP baseline year) 
and identifies new budgets for the WMD for VOC and NOX for 
each updated RFP milestone year through 2026. The budgets in the 2018 
SIP Update replace the budgets contained in the 2016 WMD Attainment 
Plan. Like the budgets in the 2016 WMD Attainment Plan, the budgets in 
the 2018 SIP Update were calculated using EMFAC2014, the version of 
CARB's EMFAC model approved by the EPA for estimating emissions from 
on-road vehicles operating in California at the time the 2016 WMD 
Attainment Plan and 2018 SIP Update were developed. The budgets in the 
2018 SIP Update reflect updated VMT estimates from SCAG's 2016-2040 
Regional Transportation Plan/Sustainable Communities Strategy, 
Amendment 2, adopted in July 2017, and align with the emissions 
inventory, RFP and attainment demonstrations in the 2016 WMD Attainment 
Plan. Additionally, the budgets in the 2018 SIP Update are more precise 
because they are rounded up to the nearest tenth of a tpd, instead of 
the nearest whole number.\135\
---------------------------------------------------------------------------

    \135\ For instance, the 2016 WMD Attainment Plan estimates that 
2026 on-road vehicle emissions (summer planning inventory) would be 
7 tpd for VOC and 11 tpd for NOX. See Appendix A, A-23 
through A-26. The corresponding budgets from the 2018 SIP Update are 
6.2 tpd for VOC and 10.2 tpd for NOX. See Table VI-3 and 
surrounding discussion in Section V of the TSD for this action for 
additional detail.
---------------------------------------------------------------------------

    The conformity budgets for NOX and VOC in the 2018 SIP 
Update for the WMD are provided in Table 4 below.

                                   Table 4--West Mojave Desert Motor Vehicle Emissions Budgets in the 2018 SIP Update
                                                             [tpd, average summer weekday] a
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       2020                            2023                            2026
                                                         -----------------------------------------------------------------------------------------------
                                                                VOC             NOX             VOC             NOX             VOC             NOX
--------------------------------------------------------------------------------------------------------------------------------------------------------
On-Road Inventory.......................................            7.87           17.57            6.73           10.98            5.98            9.79
Safety Margin...........................................  ..............  ..............  ..............  ..............             0.2             0.4
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................            7.87           17.57            6.73           10.98            6.18           10.19

[[Page 24826]]

 
MVEBs \b\...............................................             7.9            17.6             6.8            11.0             6.2            10.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Source: Table VI-3 from the 2018 SIP Update.
\b\ Rounded up to the next tenth of a ton.

    The submittal letters for both the 2016 WMD Attainment Plan and the 
2018 SIP Update include a request from CARB that the EPA limit the 
duration of our approval of the budgets to last only until the 
effective date of future EPA adequacy findings for replacement 
budgets.\136\
---------------------------------------------------------------------------

    \136\ Letter dated April 9, 2021, from Michael Benjamin, Chief, 
Air Quality Planning and Science Division, CARB, to Deborah Jordan, 
Acting Regional Administrator, EPA Region IX, and letter dated 
December 5, 2018, from Richard Corey, Executive Officer, CARB, to 
Mike Stoker, Regional Administrator, EPA Region IX.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    As part of our review of the approvability of the budgets in the 
2018 SIP Update, we have evaluated the budgets using our adequacy 
criteria in 40 CFR 93.118(e)(4) and (5). We will complete the adequacy 
review concurrently with our final action on the 2016 WMD Attainment 
Plan. The EPA is not required under its transportation conformity rule 
to find budgets adequate prior to proposing approval of them.\137\ 
Today, the EPA is announcing that the adequacy process for these 
budgets begins and the public has 30 days to comment on their adequacy, 
per the transportation conformity regulation at 40 CFR 93.118(f)(2)(i) 
and (ii).
---------------------------------------------------------------------------

    \137\ 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).
---------------------------------------------------------------------------

    As documented in Table 5 of section V of the EPA's TSD for this 
proposal, we preliminarily conclude that the budgets in the 2018 SIP 
Update for the West Mojave Desert meet each adequacy criterion. While 
adequacy and approval are two separate actions, reviewing the budgets 
in terms of the adequacy criteria informs the EPA's decision to propose 
to approve the budgets. We have completed our detailed review of the 
2016 WMD Attainment Plan and the 2018 SIP Update, and we are proposing 
herein to approve the attainment and RFP demonstrations. We have also 
reviewed the budgets in the 2018 SIP Update and found that they are 
consistent with the attainment and RFP demonstrations for which we are 
proposing approval, are based on control measures that have already 
been adopted and implemented, and meet all other applicable statutory 
and regulatory requirements, including the adequacy criteria in 40 CFR 
93.1118(e)(4) and (5). Therefore, we are proposing to approve the 2023 
and 2026 budgets in the 2018 SIP Update. At the point when we finalize 
our adequacy process or approve the budgets for the 2008 ozone NAAQS in 
the 2018 SIP Update as proposed (whichever occurs first; note that they 
could also occur concurrently per 40 CFR 93.118(f)(2)(iii)), then these 
budgets will replace the budgets that we previously found adequate for 
use in transportation conformity determinations.\138\
---------------------------------------------------------------------------

    \138\ We found adequate the budgets from the Antelope Valley-
Western Mojave Desert 8-hour Ozone Early Progress Plan (February 
2008) for the 1997 ozone NAAQS at 73 FR 24594 (May 5, 2008). The 
budgets in Table VI-3 of the 2018 SIP Update for the 2008 ozone 
NAAQS are lower than the corresponding budgets approved for the 1997 
ozone NAAQS. The current budgets of 22 tpd for VOC and 77 tpd for 
NOX for all years, would be replaced by budgets of 6.8 
tpd for VOC and 11.0 tpd for NOX in 2023 and 6.2 tpd for 
VOC and 10.2 tpd for NOX in 2026.
---------------------------------------------------------------------------

    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 year(s) addressed by 
the previously approved SIP submittal 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.\139\
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    \139\ 40 CFR 93.118(e)(1).
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    In this instance, CARB's submittal letters transmitting the 2016 
WMD Attainment Plan and 2018 SIP Update requested that we limit the 
duration of our approval to the effective date of an EPA adequacy 
finding for subsequently submitted budgets, and on April 9, 2021, CARB 
provided further explanation for its request. Generally, we will 
consider a state's request to limit an approval of a budget only if the 
request includes the following elements: \140\
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    \140\ 67 FR 69139 (November 15, 2002) (final action limiting our 
prior approval of budgets in certain California SIPs).
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     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.
    CARB's request includes an explanation for why the budgets have 
become, or will become, outdated or deficient. In short, CARB requested 
that we limit the duration of the approval of the budgets in light of 
the EPA's recent approval of EMFAC2017, an updated version of the 
EMFAC2014 model used for the budgets in the 2018 SIP Update. EMFAC2017 
updates vehicle mix and emissions data of the previously approved 
version of the model, EMFAC2014.
    In light of the approval of EMFAC2017, CARB requests that the 
budgets from the 2016 WMD Attainment Plan, for which we are proposing 
approval in this action, will be revised using EMFAC2017 in 2022. 
CARB's request also states, ``without the ability to replace the 
applicable transportation conformity emissions budgets with submitted 
budgets found adequate using the budget adequacy process, the benefits 
of using the updated data may not be realized for a year or more after 
the SIPs are submitted, due to the SIP approval process.''
    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

[[Page 24827]]

40 CFR 93.118(e)(4) for the 2015 ozone NAAQS in 2022,\141\ 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 2018 SIP Update until we find revised 
budgets based on EMFAC2017 to be adequate.
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    \141\ 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).
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I. Other Clean Air Act Requirements Applicable to Severe Ozone 
Nonattainment Areas

    In addition to the requirements discussed above, title 1, subpart D 
of the CAA includes other provisions applicable to Severe ozone 
nonattainment areas, such as the WMD. We describe these provisions and 
their current status below for informational purposes only.
1. Enhanced Vehicle Inspection and Maintenance Programs
    Section 182(c)(3) of the CAA requires states with ozone 
nonattainment areas classified under subpart 2 as Serious or above to 
implement an enhanced motor vehicle I/M program in each urbanized area 
within the nonattainment area. As discussed in Section III.G.3 of this 
document, Section 182(c)(3) further explains that urbanized areas are 
``defined by the Bureau of the Census, with a 1980 population of 
200,000 or more.'' Because parts of the MDAQMD within the WMD were not 
considered urbanized areas in 1980, only part of the WMD is subject to 
enhanced I/M.\142\
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    \142\ As described in section III.G.2 of this document, the 
State has committed to adopt a contingency measure to implement 
enhanced I/M throughout the portion of the WMD that is currently 
subject to basic I/M, in the event that the area fails to meet an 
RFP milestone or to attain the 2008 NAAQS by the attainment date.
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    Consistent with the 2008 Ozone SRR, no new I/M programs are 
currently required for nonattainment areas for the 2008 ozone 
NAAQS.\143\ The EPA previously approved the California I/M program in 
the West Mojave Desert as meeting the requirements of the CAA and 
applicable EPA regulations for enhanced I/M programs.\144\
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    \143\ 2008 Ozone SRR, 80 FR 12264, at 12283 (March 6, 2015).
    \144\ 75 FR 38023 (July 1, 2010).
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2. New Source Review Rules
    Section 182(a)(2)(C) of the CAA requires states to develop SIP 
revisions containing permit programs for each of its ozone 
nonattainment areas. The SIP revisions are to include requirements for 
permits in accordance with CAA sections 172(c)(5) and 173 for the 
construction and operation of each new or modified major stationary 
source for VOC and NOX anywhere in the nonattainment 
area.\145\ The 2008 Ozone SRR includes provisions and guidance for 
nonattainment new source review (NSR) programs.\146\ We will address 
the NSR requirements for the 2008 ozone NAAQS in the WMD in a separate 
action.
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    \145\ See also CAA sections 182(e).
    \146\ 80 FR 12264 (March 6, 2015).
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3. Clean Fuels Fleet Program
    Sections 182(c)(4)(A) and 246 of the CAA require California to 
submit to the EPA for approval into the SIP measures to implement a 
Clean Fuels Fleet Program. Section 182(c)(4)(B) of the CAA allows 
states to opt out of the federal clean-fuel vehicle fleet program by 
submitting a SIP revision consisting of a program or programs that will 
result in at least equivalent long-term reductions in ozone precursors 
and toxic air emissions.
    In 1994, CARB submitted a SIP revision to the EPA to opt out of the 
federal clean-fuel fleet program and included a demonstration that 
California's low-emissions vehicle program achieved emissions 
reductions at least as large as would be achieved by the federal 
program. The EPA approved the SIP revision to opt out of the federal 
program on August 27, 1999.\147\ There have been no changes to the 
federal Clean Fuels Fleet program since the EPA approved the California 
SIP revision to opt out of the federal program, and thus, no 
corresponding changes to the SIP are required. Thus, we find that the 
California SIP revision to opt out of the federal program, as approved 
in 1999, meets the requirements of CAA sections 182(c)(4)(A) and 246 
for the WMD for the 2008 ozone standards.
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    \147\ 64 FR 46849 (August 27, 1999).
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4. Gasoline Vapor Recovery
    Section 182(b)(3) of the CAA requires states to submit a SIP 
revision by November 15, 1992, that requires owners or operators of 
gasoline dispensing systems to install and operate gasoline vehicle 
refueling vapor recovery (``Stage II'') systems in ozone nonattainment 
areas classified as Moderate and above. California's ozone 
nonattainment areas implemented Stage II vapor recovery well before the 
passage of the CAA Amendments of 1990.\148\
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    \148\ General Preamble, 57 FR 13498 at 13514 (April 16, 1992).
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    Section 202(a)(6) of the CAA requires the EPA to promulgate 
standards requiring motor vehicles to be equipped with onboard 
refueling vapor recovery (ORVR) systems. The EPA promulgated the first 
set of ORVR system regulations in 1994 for phased implementation on 
vehicle manufacturers, and since the end of 2006, essentially all new 
gasoline-powered light- and medium-duty vehicles are ORVR-
equipped.\149\ Section 202(a)(6) also authorizes the EPA to waive the 
SIP requirement under CAA section 182(b)(3) for installation of Stage 
II vapor recovery systems after such time as the EPA determines that 
ORVR systems are in widespread use throughout the motor vehicle fleet. 
Effective May 16, 2012, the EPA waived the requirement of CAA section 
182(b)(3) for Stage II vapor recovery systems in ozone nonattainment 
areas regardless of classification.\150\ Thus, a SIP submittal meeting 
CAA section 182(b)(3) is not required for the 2008 ozone NAAQS.
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    \149\ 77 FR 28772, at 28774 (May 16, 2012).
    \150\ 40 CFR 51.126(b).
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    While a SIP submittal meeting CAA section 182(b)(3) is not required 
for the 2008 ozone NAAQS, under California state law (i.e., Health and 
Safety Code section 41954), CARB is required to adopt procedures and 
performance standards for controlling gasoline emissions from gasoline 
marketing operations, including transfer and storage operations. State 
law also authorizes CARB, in cooperation with local air districts, to 
certify vapor recovery systems, to identify defective equipment and to 
develop test methods. CARB has adopted numerous revisions to its vapor 
recovery program regulations and continues to rely on its vapor 
recovery program to achieve emissions reductions in ozone nonattainment 
areas in California.
    In the WMD, the installation and operation of CARB-certified vapor 
recovery equipment is required and enforced through AVAQMD Rule 461, 
``Gasoline Transfer and Dispensing,'' approved into the SIP on October 
21, 2008, and MDAQMD Rule 461, ``Gasoline Transfer and Dispensing,'' 
approved into the SIP on May 1, 2020.\151\
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    \151\ 76 FR 5277 (January 31, 2011) and 85 FR 25293 (May 1, 
2020).
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5. Enhanced Ambient Air Monitoring
    Section 182(c)(1) of the CAA requires that all ozone nonattainment 
areas

[[Page 24828]]

classified as Serious or above implement measures to enhance and 
improve monitoring for ambient concentrations of ozone, NOX, 
and VOC, and to improve monitoring of emissions of NOX and 
VOC. The enhanced monitoring network for ozone is referred to as the 
photochemical assessment monitoring station (PAMS) network. The EPA 
promulgated final PAMS regulations on February 12, 1993.\152\
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    \152\ 58 FR 8452 (February 12, 1993).
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    On November 10, 1993, CARB submitted to the EPA a SIP revision 
addressing the PAMS network for six ozone nonattainment areas in 
California, including the WMD, to meet the enhanced monitoring 
requirements of CAA section 182(c)(1). The EPA determined that the PAMS 
SIP revision met all applicable requirements for enhanced monitoring 
and the EPA PAMS regulations and approved the PAMS submittal into the 
California SIP.\153\
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    \153\ 82 FR 45191 (September 28, 2017). This action addressed 1-
hour ozone nonattainment areas. The area identified as Southeast 
Desert Modified Air Quality Management Area for the 1-hour ozone 
NAAQS has been split into two separate nonattainment areas for the 
1997 and 2008 ozone NAAQS, the WMD and Riverside County (Coachella 
Valley).
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    Prior to 2006, the EPA's ambient air monitoring regulations in 40 
CFR part 58, ``Ambient Air Quality Surveillance,'' set forth specific 
SIP requirements (see former 40 CFR 52.20). In 2006, the EPA 
significantly revised and reorganized 40 CFR part 58.\154\ Under 
revised 40 CFR part 58, SIP revisions are no longer required; rather, 
compliance with EPA monitoring regulations is established through 
review of required annual monitoring network plans.\155\ The 2008 Ozone 
SRR made no changes to these requirements.\156\
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    \154\ 71 FR 61236 (October 17, 2006).
    \155\ 40 CFR 58.2(b) now provides that, ``The requirements 
pertaining to provisions for an air quality surveillance system in 
the SIP are contained in this part.''
    \156\ The 2008 ozone SRR addresses PAMS-related requirements at 
80 FR 12264, 12291 (March 6, 2015).
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    The 2016 WMD Attainment Plan does not specifically address the 
enhanced ambient air monitoring requirement in CAA section 182(c)(1). 
However, we note that CARB includes the ambient monitoring network 
within the WMD in its annual monitoring network plan that is submitted 
to the EPA, and that we have approved the most recent annual monitoring 
network plan (``Annual Network Plan Covering Monitoring Operations in 
25 California Air Districts, July 2020'' or ``2018 ANP''), which 
includes the enhanced ambient air monitoring element for the WMD.\157\ 
Based on our review and approval of the 2020 ANP with respect to the 
WMD and our earlier approval of the PAMS SIP revision, we propose to 
find that CARB, AVAQMD and MDAQMD meet the enhanced monitoring 
requirements under CAA section 182(c)(1) for the WMD with respect to 
the 2008 ozone NAAQS.
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    \157\ The EPA approved the 2020 ANP in a letter dated November 
5, 2020, from Gwen Yoshimura, Manager, Air Quality Analysis Office, 
EPA Region IX, to Ravi Ramalingam, Chief, Consumer Products and Air 
Quality Assessment Branch, Air Quality Planning and Science 
Division, CARB.
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6. CAA Section 185 Fee Program
    Section 185 of the CAA requires that the SIP for each Severe and 
Extreme ozone nonattainment area provide that, if the area fails to 
attain by its applicable attainment date, each major stationary source 
of VOC and NOX located in the area shall pay a fee to the 
state as a penalty for such failure for each calendar year beginning 
after the attainment date, until the area is redesignated as an 
attainment area for ozone. States are not yet required to submit a SIP 
revision that meets the requirements of CAA section 185 for the 2008 
ozone NAAQS.\158\
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    \158\ See 40 CFR 51.1117. For the WMD, a section 185 SIP 
revision for the 2008 ozone standards will be due on July 20, 2022.
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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 following portions of the 2016 WMD Attainment Plan 
for the 2008 ozone NAAQS, submitted by CARB on June 2, 2017, and the 
2018 SIP Update, submitted on December 11, 2018:
     Base year emissions inventory element in the 2016 WMD 
Attainment Plan as meeting the requirements of CAA sections 172(c)(3) 
and 182(a)(1) and 40 CFR 51.1115;
     Emissions statement element in the 2016 WMD Attainment 
Plan as meeting the requirements of CAA section 182(a)(3)(B) and 40 CFR 
51.1102;
     RACM demonstration element in the 2016 WMD Attainment 
Plan, as meeting the requirements of CAA section 172(c)(1) and 40 CFR 
51.1112(c);
     Attainment demonstration element in the 2016 WMD 
Attainment Plan as meeting the requirements of CAA section 182(c)(2)(A) 
and 40 CFR 51.1108;
     RFP demonstration element in the 2018 SIP Update as 
meeting the requirements of CAA sections 172(c)(2), 182(b)(1), and 
182(c)(2)(B), and 40 CFR 51.1110(a)(2)(ii);
     VMT emissions offset demonstration element in the 2016 WMD 
Attainment Plan as meeting the requirements of CAA section 182(d)(1)(A) 
and 40 CFR 51.1102; and
     Motor vehicle emissions budgets in the 2018 SIP Update for 
the 2023 RFP milestone year and the 2026 attainment year (see Table 4 
of this notice) because they are consistent with the RFP and attainment 
demonstrations proposed for approval herein and meet the other criteria 
in 40 CFR 93.118(e).
    We are also proposing to find that the:
     California SIP revision to opt out of the federal Clean 
Fuels Fleet Program meets the requirements of CAA sections 182(c)(4)(A) 
and 246 and 40 CFR 51.1102 with respect to the WMD;
     Enhanced monitoring in the WMD meets the requirements of 
CAA section 182(c)(1) and 40 CFR 51.1102; and
     Enhanced vehicle inspection and maintenance program 
element in the WMD meets the requirements of CAA section 182(c)(3) and 
40 CFR 51.1102.
    Lastly, we are proposing, under CAA section 110(k)(4), to 
conditionally approve the contingency measure element of the 2016 WMD 
Attainment Plan as meeting the requirements of CAA sections 172(c)(9) 
and 182(c)(9) for RFP contingency measures. Our proposed approval is 
based on commitments by the District and CARB to supplement the element 
through submission, as a SIP revision (within one year of final 
conditional approval action), a MDAQMD Board resolution detailing the 
circumstances, timing, and procedure for implementing enhanced vehicle 
inspection and maintenance for areas within WMD currently subject to 
basic I/M, if an RFP milestone is not met or the area fails to attain 
the 2008 ozone NAAQS by the attainment date.
    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

    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

[[Page 24829]]

requirements beyond those imposed by state law. For that reason, 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);
     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, 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).

List of Subjects in 40 CFR Part 52

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

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

    Dated: May 4, 2021.
Deborah Jordan,
Acting Regional Administrator, Region IX.
[FR Doc. 2021-09842 Filed 5-7-21; 8:45 am]
BILLING CODE 6560-50-P