[Federal Register Volume 88, Number 61 (Thursday, March 30, 2023)]
[Proposed Rules]
[Pages 19034-19045]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-06578]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2022-0972; FRL-R9-10529-01]


Second 10-Year Maintenance Plan for the Coso Junction PM-10 
Planning Area; California

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the ``Coso Junction PM10 Planning Area Second 10-
Year Maintenance Plan'' (``Coso Junction Second Maintenance Plan'' or 
``Plan'') as a revision to the state implementation plan (SIP) for the 
State of California. The Coso Junction Second Maintenance Plan 
includes, among other elements, a base year emissions inventory, a 
maintenance demonstration, and contingency provisions. The EPA is 
proposing this action because the SIP revision meets the applicable 
statutory and regulatory requirements for such plans. The EPA is also 
proposing to find the contribution of motor vehicles to the area's 
continued attainment of the 1987 PM10 standard to be 
insignificant and is initiating the adequacy review process for this 
insignificance finding through this Notice of Proposed Rule Making 
(NPRM). If this insignificance finding is finalized, the area would not 
have to complete a regional emissions analysis for any transportation 
conformity determinations necessary for the Coso Junction Planning Area 
(CJPA).

DATES: Comments must be received on or before May 1, 2023.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2022-0972 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 https://www.epa.gov/dockets/commenting-epa-dockets. If you need assistance in a 
language other than English or if you are a person with a disability 
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: Lindsay Wickersham, EPA Region IX 
(ARD-2), 75 Hawthorne Street, San Francisco, CA 94105. By phone: (415) 
947-4192, or by email at [email protected].

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

Table of Contents

I. Background
    A. The PM10 National Ambient Air Quality Standards
    B. The Coso Junction PM10 Planning Area
    C. Air Quality in the Coso Junction Planning Area
II. California's State Implementation Plan Submittal
III. Procedural Requirements for Adoption and Submittal of State 
Implementation Plan Revisions
IV. Requirements for Second 10-Year Maintenance Plans
V. Evaluation of the Coso Junction Second Maintenance Plan
    A. Emissions Inventories Overview
    B. Maintenance Demonstration
    C. PM10 Air Quality Monitoring Network
    D. Verification of Continued Attainment
    E. Contingency Provisions
    F. Motor Vehicle Emissions Budgets for Transportation Conformity
VI. Environmental Justice Considerations
VII. Proposed Action and Request for Public Comment
VIII. Statutory and Executive Order Reviews

I. Background

A. The PM10 National Ambient Air Quality Standards

    Section 109 of the Clean Air Act (CAA or the ``Act'') grants the 
EPA the authority to set national ambient air quality standards (NAAQS 
or ``standards'') for certain ambient air pollutants in order to 
protect public health and welfare.\1\ Particulate matter (PM) refers to 
the mixture of solid particles and liquid droplets found in the air. PM 
is among the ambient air pollutants for which the EPA has established 
health-based standards. PM10 is defined as inhalable 
particles with diameters that are 10 micrometers or less. 
PM10 can cause adverse health effects by penetrating deep 
into the lungs and blood stream, leading to lung damage, increased 
respiratory disease, and premature death. Children, the elderly, and 
people with asthma and heart conditions are the most vulnerable.
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    \1\ CAA section 109(b). For a given air pollutant, ``primary'' 
standards are those determined by the EPA as requisite to protect 
the public health. ``Secondary'' standards are those determined by 
the EPA as requisite to protect the public welfare from any known or 
anticipated adverse effects associated with the presence of such air 
pollutant in the ambient air.
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    On July 1, 1987, the EPA established primary and secondary NAAQS 
for PM10.\2\ At that time, the EPA established two 
PM10 standards: an annual standard and a 24-hour 
standard.\3\ Effective December 18, 2006, the EPA revoked the annual 
PM10 standard but retained the 24-hour PM10 
standard.\4\ An area attains the 24-hour standard of 150 micrograms per 
cubic meter ([micro]g/m\3\) when the expected number of days per 
calendar year with a 24-hour concentration above the standard (referred 
to as an ``exceedance''),\5\ averaged over three years, is equal to or 
less than one. The expected number of exceedances averaged over a 
three-year period at any regulatory monitor is known as the 
PM10 design value. The PM10 design value for the 
area is the highest design value within the nonattainment area.\6\
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    \2\ 52 FR 24634.
    \3\ The primary and secondary standards were set at the same 
level for both the 24-hour and the annual PM10 standards.
    \4\ 71 FR 61144 (October 17, 2006).
    \5\ An exceedance is defined as a daily value that is above the 
level of the 24-hour standard (i.e., 150 [micro]g/m\3\) after 
rounding to the nearest 10 [micro]g/m\3\ (i.e., values ending in 
five or greater are to be rounded up). Thus, a recorded value of 154 
[micro]g/m\3\ would not be an exceedance because it would be rounded 
to 150 [micro]g/m\3\. A recorded value of 155 [micro]g/m\3\ would be 
an exceedance because it would be rounded to 160 [micro]g/m\3\. 40 
CFR part 50, appendix K, section 1.0.
    \6\ 40 CFR 50.6 and 40 CFR part 50, appendix K. The comparison 
with the allowable expected exceedance rate of one per year averaged 
over three years is made in terms of a number rounded to the nearest 
tenth (fractional values equal to or greater than 0.05 are to be 
rounded up; e.g., an exceedance rate of 1.05 would be rounded to 
1.1, which is the minimum design value for nonattainment). 40 CFR 
part 50, appendix K, section 2.1(b).
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    Generally, the EPA determines whether an area's air quality is 
meeting the PM10 NAAQS based on the most

[[Page 19035]]

recent complete,\7\ quality-assured, and certified data measured at 
established state and local air monitoring stations (SLAMS) in the 
nonattainment area and entered into the EPA Air Quality System (AQS) 
database. Data from air monitoring sites operated by state, local, or 
tribal agencies in compliance with the EPA's monitoring requirements 
must be submitted to AQS. These monitoring agencies annually certify 
that these data are accurate to the best of their knowledge. 
Accordingly, the EPA relies primarily on data in AQS when determining 
the attainment status of an area.\8\ All valid data are reviewed to 
determine the area's air quality status in accordance with 40 CFR part 
50, appendix K.
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    \7\ For PM10, a complete year of air quality data 
includes all four calendar quarters with each quarter having valid 
data on a minimum of 75 percent of the scheduled PM10 
sampling days. 40 CFR part 50, appendix K, section 2.3(a).
    \8\ 40 CFR 50.6; 40 CFR part 50, appendix J; 40 CFR part 53; and 
40 CFR part 58, appendices A, C, D, and E.
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B. The Coso Junction PM10 Planning Area

    Through its enactment of the CAA Amendments of 1990, Congress 
designated certain areas of the country as nonattainment areas for the 
PM10 NAAQS. The Searles Valley Planning Area was one of the 
areas designated as nonattainment. In 1991, the EPA classified the 
Searles Valley planning area as a ``Moderate'' PM10 
nonattainment area.\9\
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    \9\ 52 FR 29383 (August 7, 1987).
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    The Searles Valley Planning Area included three subregions (Coso 
Junction, Indian Wells Valley, and Trona) under the planning 
jurisdiction of different air pollution control agencies. On August 6, 
2002, the EPA changed the boundaries of the Searles Valley 
PM10 nonattainment area by dividing this area into three 
separate, newly-created PM10 nonattainment areas, one of 
which is the CJPA.\10\ The CJPA is under the planning jurisdiction of 
the Great Basin Unified Air Pollution Control District (GBUAPCD or 
``District'').\11\ It covers approximately 792 square miles of sparsely 
populated, arid, high desert that receives less than five inches of 
rain per year. The CJPA is flanked by the Sierra Nevada Mountains to 
the west and the Coso Range to the east. A majority of the CJPA is 
covered by the China Lake Naval Air Weapons Station, which is generally 
restricted from public access.
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    \10\ 67 FR 50805 (August 6, 2002).
    \11\ For a description of the geographic boundaries of the CJPA, 
see 40 CFR 81.305.
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    Owens Lake, located in neighboring Inyo County and within the Owens 
Valley Planning Area, is also under the jurisdiction of GBUAPCD.\12\ 
Starting in 1913, the Los Angeles Department of Water and Power began 
diverting water from Owens Lake until the lake was almost completely 
dry. Winds blowing over the dry, alkaline bed of Owens Lake have 
produced among the highest measured concentrations of PM10 
ever recorded and can have impacts as far as 150 miles away.\13\ To 
mitigate impacts of Owens Lake dust, the GBUAPCD developed the controls 
and plans for the Owens Valley Planning Area with many participants 
including the California Air Resources Board (CARB), Los Angeles 
Department of Water and Power, the City of Los Angeles, tribal 
governments, federal land managers, the Navy, the State Lands 
Commission, and members of the public.
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    \12\ For the history of Owens Lake and its impact on the CJPA, 
see 75 FR 36023 (June 24, 2010).
    \13\ 64 FR 34173 (June 25, 1999).
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    Since approval of the 1998 PM10 Plan for the Owens 
Valley Planning Area,\14\ the GBUAPCD and City of Los Angeles have 
worked consistently to refine and optimize the complex set of control 
measures leading to substantial reductions of PM10 from the 
dry Owens Lakebed and surrounding near-lake sources. Decades of work by 
the GBUAPCD and the City of Los Angeles culminated in the District's 
adoption and the EPA's approval of Rule 433, ``Control of Particulate 
Emissions at Owens Lake,'' into the SIP in 2016.\15\ Rule 433 requires 
the City of Los Angeles to implement dust control measures, including 
shallow flooding, managed vegetation, and application of gravel on 
designated areas of Owens Lake.\16\ The implementation of these dust 
control measures has led to more than a 90 percent decrease in 
emissions from Owens Lake \17\ and significant improvement in the air 
quality in the CJPA.\18\
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    \14\ 82 FR 13390 (March 13, 2017).
    \15\ 81 FR 95473 (December 28, 2016).
    \16\ GPUAPCD Rule 433, ``Control of Particulate Emissions at 
Owens lake,'' adopted April 13, 2016.
    \17\ 75 FR 36023.
    \18\ The number of monitored and expected exceedances at the 
Rose Valley monitoring station in the CJPA has dropped from a high 
of 12 exceedances per year to the value of 1 per year, excluding 
exceptional events, in 2020. See Table 2 in the Coso Junction Second 
Maintenance Plan for a summary of exceedances from 1985 through 
2020.
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    On May 19, 2010, the EPA determined that the CJPA had attained the 
24-hour PM10 NAAQS.\19\ The determination was based on 
complete, quality-assured, and certified ambient air monitoring data 
that showed the area monitored attainment of the PM10 NAAQS 
during 2006-2008.\20\ On September 3, 2010, the EPA finalized approval 
of the submitted ``2010 PM10 Maintenance Plan and 
Redesignation Request for the Coso Junction Planning Area'' (``2010 
Maintenance Plan'') and redesignated the CJPA to attainment, effective 
October 4, 2010.\21\ This redesignation was based on EPA's review of 
the 2010 Maintenance Plan, air quality monitoring data, and other 
relevant materials that satisfied all requirements for redesignation of 
the CJPA to attainment, pursuant to CAA sections 107(d)(3)(E) and 175A. 
Additionally, the maintenance plan was approved as it was consistent 
with applicable CAA provisions and EPA guidance.
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    \19\ 75 FR 27944.
    \20\ Id.
    \21\ 75 FR 54031.
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    GBUAPCD is a monitoring organization within the CARB Primary 
Quality Assurance Organization. GBUAPCD operates the PM10 
monitoring network in the CJPA. GBUAPCD submits annual monitoring 
network plans to the EPA that describe the monitoring network operated 
by GBUAPCD within the CJPA and discuss the status of the air monitoring 
network, as required under 40 CFR 58.10.\22\ The EPA regularly reviews 
these annual plans for compliance with the applicable reporting 
requirements in 40 CFR part 58. With respect to PM10, the 
EPA has found that GBUAPCD's network plans meet the applicable 
reporting requirements for the area under 40 CFR part 58, appendix 
D.\23\ GBUAPCD annually certifies that the data it submits to AQS are 
complete and quality-assured.\24\
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    \22\ The most recent annual network plan was submitted via email 
dated April 26, 2022, from Chris Howard, GBUAPCD, to Gwen Yoshimura, 
EPA Region IX, Subject: ``Great Basin Unified APCD Ambient Air 
Monitoring Data Certification for 2021,'' with attachment.
    \23\ For example, see letter dated December 19, 2022, from Gwen 
Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to 
Phillip Kiddoo, Air Pollution Control Officer, GBUAPCD.
    \24\ See email dated April 26, 2022, from Chris Howard, GBUAPCD, 
to Gwen Yoshimura, EPA Region IX, Subject: ``Great Basin Unified 
APCD Ambient Air Monitoring Data Certification for 2021,'' with 
attachment.
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    The District operates one PM10 monitoring station for 
the CJPA. The monitoring station is located near the State of 
California Coso Junction rest area in Rose Valley.\25\ The monitoring 
site is a designated SLAMS and collects hourly PM10 data in 
accordance with 40 CFR parts 50, 53, and 58.
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    \25\ See Figure 3 in the Coso Junction Second Maintenance Plan.

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[[Page 19036]]

C. Air Quality in the Coso Junction Planning Area

    While the CJPA has had annual average PM10 
concentrations of less than 20 [micro]g/m\3\ over the past 10 years, 
the PM10 monitoring data within the CJPA includes 17 
exceedances of the standard recorded during 2010-2020, as detailed in 
Table 1 of the Coso Junction Second Maintenance Plan.\26\ Since the 
submittal of the Plan, an additional three exceedances occurred in 
2021; these exceedances occurred on September 19, September 27, and 
October 11.
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    \26\ Coso Junction Second Maintenance Plan, Appendix A includes 
the daily average PM10 monitor readings from the CJPA and 
surrounding monitor stations for every day from January 1, 2010, to 
December 31, 2020.
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    On September 1, 2022, the District and CARB submitted a document 
titled, ``Discussion of Coso Junction Federal PM10 
Exceedances Not Requested for Exclusion from the NAAQS, 2010 through 
2021,'' (``Exceedance Discussion'').\27\ The Exceedance Discussion 
documents the District's response to the exceedances that were not 
requested for exclusion as exceptional events between the years of 2010 
and 2021. For exceedances that occurred before the adoption of the Coso 
Junction Second Maintenance Plan by the State on September 23, 2021, 
the District implemented its contingency plan as outlined in Section 
5.1 of the 2010 Maintenance Plan. Exceedances that occurred after 
September 23, 2021, were subject to the contingency plan described in 
Section 7 of the Coso Junction Second Maintenance Plan, and in Section 
V.E of this document. Details of the subsequent investigations and 
District actions taken are outlined in Table 3 of the Exceedance 
Discussion and are consistent with the language of both the 2010 
Maintenance Plan and the Coso Junction Second Maintenance Plan.\28\ 
Table 1 of this document lists the exceedances that occurred, the 
source of the exceedance, and the action taken by the District.
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    \27\ Submitted via email on September 1, 2022 from Sylvia 
Vanderspek, CARB, to Gwen Yoshimura, EPA Region IX, Subject: ``FW: 
Coso Junction Initial Notification Forms for 2nd PM10 MP 
Contingency.'' with attachments.
    \28\ Id., attachment titled ``Discussion of PM10 
Exceedances at Coso Junction 2010 through 2021.pdf.''

                          Table 1--Exceedances in Coso Junction From 2010 Through 2021
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        Exceedance date              Source of exceedance                  District course of action
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2/8/2011......................  North wind: regional event...  2010 Maintenance Plan contingency provisions
                                                                triggered. Phase 7a and Phase 8 dust controls
                                                                ordered and implemented on Owens Lake.
11/30/2011....................  North wind: regional event...  2010 Maintenance Plan contingency provisions
                                                                triggered. Phase 7a and Phase 8 dust controls
                                                                ordered and implemented on Owens Lake.
12/1/2011.....................  North wind: regional event     2010 Maintenance Plan contingency provisions
                                 compounded by Owens Lake       triggered. Phase 7a and Phase 8 dust controls
                                 emissions, notably Phase 8     ordered and implemented on Owens Lake.
                                 pre-gravel.
3/6/2012......................  West wind: local sources.....  Not requested for exclusion as an Exceptional
                                                                Event. No local sources identified as requiring
                                                                control. No contingency provisions triggered.
8/7/2013......................  West wind: flash flood         Requested for exclusion as Exceptional Event; the
                                 deposits.                      EPA deferred review.
9/25/2013.....................  West wind: flash flood         Requested for exclusion as Exceptional Event; the
                                 deposits.                      EPA deferred review.
2/16/2014.....................  West wind: flash flood         Requested for exclusion as Exceptional Event; the
                                 deposits.                      EPA deferred review.
4/25/2014.....................  West wind: flash flood         Requested for exclusion as Exceptional Event; The
                                 deposits.                      EPA deferred review.
12/31/2014....................  North wind: regional event,    No Owens Lake or other sources identified as
                                 compounded by sources south    requiring control. No contingency provisions
                                 of Owens Lake.                 triggered.
11/16/2016....................  West wind: local sources.....  Utilized existing District regulations, including
                                                                District Rule 401, to ensure compliance with
                                                                local sources.
3/31/2017.....................  North wind: regional event...  2010 Maintenance Plan contingency provisions
                                                                triggered. District enforced timeline for
                                                                ordered Owens Lake BACM construction and
                                                                implementation. District continued to monitor,
                                                                evaluate emissions from Owens Lake and
                                                                surrounding areas.
7/29/2017.....................  Local sources: paving          District took enforcement action to bring the
                                 operations \a\.                local emissive stationary source into compliance
                                                                under District Rule 401. No additional actions
                                                                or contingency provisions required.
12/20/2017....................  West wind: local sources.....  Utilize existing District regulations, including
                                                                District Rule 401, to ensure compliance with
                                                                local sources. No additional contingency
                                                                provisions triggered.
2/11/2018.....................  West wind: local sources.....  Utilize existing District regulations, including
                                                                District Rule 401, to ensure compliance with
                                                                local stationary sources. No additional
                                                                contingency provisions triggered.
9/2/2019......................  Regional windblown dust:       Not requested for exclusion as an Exceptional
                                 local sources.                 Event at this time due to mixed source
                                                                contributions. Health advisories issued per
                                                                District Rule 701 and the 2018 Coso Junction
                                                                Exceptional Event Mitigation Plan.
9/7/2020......................  Creek Fire/SQF Complex         Exceptional Event demonstration submitted and
                                 wildfire smoke.                concurred on by the EPA.
9/8/2020......................  Creek Fire/SQF Complex         Not requested for exclusion as an Exceptional
                                 wildfire smoke followed by     Event at this time due to mixed source
                                 regional windblown dust.       contributions. Health advisories issued per
                                                                District Rule 701 and the 2018 Coso Junction
                                                                Exceptional Event Mitigation Plan.
9/19/2021.....................  Windy Fire/KNP Complex         The District submitted request for exclusion from
                                 wildfire smoke.                contingency measure trigger calculation; the EPA
                                                                concurred.
9/27/2021.....................  Windy Fire/KNP Complex         The District submitted request for exclusion from
                                 wildfire smoke.                contingency measure trigger calculation; the EPA
                                                                concurred.
10/11/2021....................  West Wind: local sources.....  The District took enforcement action to bring the
                                                                source into compliance under existing District
                                                                rules and regulations including District Rule
                                                                401. No additional contingency provisions
                                                                triggered.
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\a\ AQS information qualifier code ``J-construction.''
Source: Exceedance Discussion, Table 1 and Table 3.


[[Page 19037]]

1. Exceedances in the Coso Junction Planning Area
    The District requested exclusion of 5 of the 17 exceedances due to 
exceptional events as defined in section 319(b) of the Act and its 
implementing regulations, referred to herein as the Exceptional Events 
Rule.\29\ The Exceptional Events Rule defines an exceptional event as 
an event and its resulting emissions that the EPA determines affects 
air quality in such a way that there is a clear causal relationship 
between the event and a monitored exceedance (or violation) that is not 
reasonably controllable or preventable. Such events can be natural (for 
example, high winds or wildfires) or can be caused by human activity 
that is unlikely to recur.\30\
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    \29\ 72 FR 13560 (March 22, 2007); revised 81 FR 68216 (October 
3, 2016).
    \30\ 40 CFR 50.1.
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    On May 3, 2016, the District submitted an initial notification of 
intent (INI) form to request exclusion under the Exceptional Events 
Rule for exceedances that occurred on four days: August 7, 2013, 
September 25, 2013, February 16, 2014, and April 25, 2014.\31\ The EPA 
deferred review of the data from these events because we did not 
anticipate the events will affect any future regulatory decision.\32\
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    \31\ Email dated May 3, 2016, from Chris Lanane, Air Monitoring 
Specialist, GBUAPCD, to Randall Chang, EPA Region IX, Subject: 
``Fwd: Exceptional Event Documentation for Coso Junction,'' with 
attachment.
    \32\ Email dated June 1, 2016, from Meredith Kurpius, EPA Region 
IX, to Chris Lanane, GBUAPCD, and Theresa Najita, CARB, Subject: 
``Coso Junction PM10 High Wind Exceptional Events.''
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    On August 24, 2021, CARB submitted a demonstration for a wildfire 
smoke PM10 exceptional event for an exceedance recorded on 
September 7, 2020, at the CJPA monitoring station.\33\ The 
demonstration includes a narrative conceptual model of the event that 
describes the event-specific characteristics, evidence showing the 
exceedance was not reasonably controllable or preventable, and evidence 
of the clear causal relationship between the wildfire smoke event and 
the exceedance flagged as an exceptional event.
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    \33\ Email dated August 24, 2021, from Clawson Candance, CARB, 
to Michael Benjamin, CARB, Subject: ``CARB letter to EPA GBUAPCD 
PM10 NEE_signed, EPA Cvr Ltr--2021 2nd Maint. Plan-EE 
Submittal-2021073_signed and GBUAPCD Exceptional Event Demonstration 
September 7 2020 FINAL,'' with three attachments. While submitted by 
CARB, the demonstrations and addendums were developed through a 
joint effort by CARB and the GBUAPCD.
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    The EPA reviewed the documentation that CARB and the District 
developed to demonstrate that the exceedance on September 7, 2020, 
meets the criteria for an exceptional event under the Exceptional 
Events Rule. As conveyed in the EPA's concurrence letter, we concurred 
that, based on the weight of evidence, the September 7, 2020 exceedance 
was caused by exceptional events due to the Creek Fire in the Sierra 
National Forest and the SQF Complex wildfire in the Sequoia National 
Forest.\34\ Accordingly, the EPA determined that the monitored 
exceedances associated with this exceptional event should be excluded 
from use in determinations of exceedances and violations, including the 
evaluation of whether the Coso Junction PM10 nonattainment 
area has maintained the standard.
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    \34\ Email dated July 12, 2022, from Anna Mebust, EPA Region IX, 
to Sylvia Vanderspek, CARB, Subject: ``EPA Concurrence on 2020 
PM10 Wildfire Exceptional Event,'' with attachments, 
``DD_Concurrence_Letter.pdf;'' 
``CosoJunctionWildfirePM10_ConcurrenceTSD.pdf.''
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    Shortly before the State submitted the Coso Junction Second 
Maintenance Plan, three additional exceedances of the PM10 
NAAQS were recorded on September 19, 2021, September 27, 2021, and 
October 11, 2021. The District has submitted INI forms and additional 
supporting information for two of the three exceedances and the EPA has 
reviewed this information as discussed further in Section I.C.2 of this 
document.\35\
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    \35\ Submitted via email on September 1, 2022, from Sylvia 
Vanderspek, CARB to Gwen Yoshimura, EPA Region IX, Subject: ``FW: 
Coso Junction Initial Notification Forms for 2nd PM10 MP 
Contingency,'' with attachments, ``INI 2010-2020 Coso Junction 
PM10.pdf,'' ``Discussion of PM10 Exceedances 
at Coso Junction 2010 through 2021.pdf,'' ``INI 2021 Coso Junction 
PM10.pdf,'' and ``Coso Junction 2021 Wildfire Smoke 
Exceedances.pdf.'' For INI forms, see attachment ``INI 2021 Coso 
Junction PM10.pdf'' and for additional information 
documenting the District's claim, see ``Coso Junction 2021 Wildfire 
Smoke Exceedances.pdf.''
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2. Design Value in the Coso Junction Planning Area
    Based on a review of air quality data during the three-year period 
covered by the Plan (2018-2020), excluding the exceedance flagged by 
CARB and GBUAPCD and concurred with by the EPA as an exceptional event, 
we find that the 2020 design value for the Coso Junction 
PM10 nonattainment area is 1.0 and therefore is consistent 
with maintenance of the standard.
    As discussed in Section I.C.1 of this document, in 2021 there were 
three additional exceedances of the PM10 NAAQS in the area. 
These additional exceedances in 2021 caused the number of exceedances 
recorded at the air monitor averaged over three consecutive years 
(i.e., 2019-2021) to be greater than 1.05. The District and CARB 
provided information to the EPA about the six exceedances that occurred 
in 2019-2021 that explained that three of the exceedances were not 
within the State's or the District's control.\36\ The information CARB 
and the District provided indicates that the September 7, 2020, 
September 19, 2021, and September 27, 2021 exceedances were all caused 
by wildfire smoke. The EPA has reviewed the information provided by the 
State regarding the 2019-2021 exceedances, and we agree that this 
information does not call into question the EPA's proposed action 
herein to approve the Coso Junction Second Maintenance Plan as 
providing for maintenance of the PM10 NAAQS.\37\
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    \36\ Id.
    \37\ Letter dated November 14, 2022, from Gwen Yoshimura, 
Manager, Air Quality Analysis Office, EPA Region IX, to Sylvia 
Vanderspek, Branch Chief, CARB, titled, ``Re: EPA Response to Coso 
Junction initial Notification Forms for 2nd PM10 MP 
Contingency, September 1, 2022.''
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II. California's State Implementation Plan Submittal

    In California, CARB is the state 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 air quality plans. In the portion of Inyo County that 
contains the CJPA, GBUAPCD develops and adopts air quality plans to 
address CAA planning requirements applicable to the CJPA. Such plans 
are then submitted to CARB for adoption and submittal to the EPA as 
revisions to the California SIP.
    On October 21, 2021, CARB submitted the ``Coso Junction 
PM10 Planning Area Second 10-Year Maintenance Plan (July 
2019)'' (``Coso Junction Second Maintenance Plan'' or ``the Plan'') for 
the 1987 24-hour PM10 NAAQS.\38\ The Coso Junction Second 
Maintenance Plan includes a demonstration that the area is expected to 
remain in attainment for the PM10 NAAQS through the last 
year of the second 10-year maintenance period, through 2030. If 
approval of this plan is finalized, the maintenance period for the CJPA 
will end on October 4, 2030, along with the conformity requirements for 
this area.
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    \38\ Letter dated October 20, 2021, from Richard W. Corey, 
Executive Officer, CARB, to Deborah Jordan, Acting Regional 
Administrator, EPA Region IX (submitted electronically October 21, 
2021).

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[[Page 19038]]

III. Procedural Requirements for Adoption and Submittal of State 
Implementation Plan Revisions

    CAA sections 110(a)(1) and (2) and section 110(l) require states to 
provide reasonable notice and opportunity for public hearing prior to 
adoption and submission of a SIP or SIP revision. To meet these 
procedural requirements, every SIP submission should include evidence 
that the state provided adequate public notice and an opportunity for a 
public hearing consistent with the EPA's implementing regulations in 40 
CFR 51.102.
    CARB's October 21, 2021 SIP submittal package includes 
documentation of the public processes used by the District and CARB to 
adopt the Coso Junction Second Maintenance Plan.\39\ As documented in 
the submittal package, on May 28, 2021, the District published a notice 
in the Tahoe Daily Tribune, a newspaper in general circulation in South 
Lake Tahoe, that a public hearing to consider adoption of the Plan 
would be held on July 1, 2021.\40\ This same notice was re-published by 
the District on May 29, 2021, in The Sheet and in The Inyo Register, 
newspapers in general circulation in Mono and Inyo counties, 
respectively.\41\ As documented in GBUAPCD Resolution No. 2021-04 
included in the SIP revision submittal package, the Governing Board of 
the GBUAPCD adopted the Coso Junction Second Maintenance Plan on July 
1, 2021, following the public hearing.\42\ CARB published on its 
website a notice of public hearing to be held on September 23, 2021, to 
consider adoption of the Plan.\43\ As evidenced by CARB Resolution 21-
19, CARB adopted the Coso Junction Second Maintenance Plan on September 
23, 2021, following a public hearing.\44\ Based on documentation 
included in the October 21, 2021 SIP revision submittal package, both 
the District and CARB have satisfied the applicable statutory and 
regulatory requirements for reasonable public notice and hearing prior 
to adoption and submission of the Plan. Therefore, the submission of 
the Coso Junction Second Maintenance Plan meets the procedural 
requirements for public notice and hearing in CAA sections 110(a) and 
110(l) and in 40 CFR 51.102.
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    \39\ In this package, CARB submitted an unsigned version of its 
``Notice of Public Meeting to Consider Coso Junction PM10 
Maintenance Plan SIP Submittal.'' On December 28, 2022, the EPA 
received a signed and dated copy of this document from the District. 
Both documents are included in the docket for this action.
    \40\ ``Notice of Public Hearing Adoption and Approval of 2021 
Coso Junction PM10 Planning Area Second 10-Year 
Maintenance Plan,'' Phillip L. Kiddoo, Air Pollution Control 
Officer, GBUAPCD.
    \41\ Id.
    \42\ GBUAPCD, ``B/O #210701-05,'' dated July 1, 2021, attested 
by Tori DeHaven, Clerk of the Board.
    \43\ ``Notice of Public Meeting to Consider Coso Junction 
PM10 Maintenance Plan SIP Submittal,'' Richard W. Corey, 
Executive Officer, CARB. Available at: https://ww2.arb.ca.gov/sites/default/files/2021-09/cosojunctionpm10sipnotice.pdf.
    \44\ Proposed agenda dated September 23, 2021, ``Coso Junction 
PM10 Planning Area Second 10-Year Maintenance Plan, 
Resolution 21-19,'' CARB.
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IV. Requirements for Second 10-Year Maintenance Plans

    Section 175A of the CAA provides the general framework for 
maintenance plans. The initial 10-year maintenance plan must provide 
for maintenance of the NAAQS for at least 10 years after redesignation, 
including any additional control measures necessary to ensure such 
maintenance. In addition, maintenance plans are to contain contingency 
provisions necessary to ensure the prompt correction of a violation of 
the NAAQS that occurs after redesignation. The contingency measures 
must include, at a minimum, a requirement that the state will implement 
all control measures contained in the nonattainment SIP prior to 
redesignation.
    Section 175A(b) of the CAA requires states to submit a subsequent 
maintenance plan revision (``second 10-year maintenance plan'') eight 
years after redesignation. The Act requires only that this second 10-
year maintenance plan maintain the applicable NAAQS for 10 years after 
the expiration of the first 10-year maintenance plan. Beyond these 
provisions, section 175A of the CAA does not define the content of a 
second 10-year maintenance plan.
    The primary guidance on maintenance plans and redesignation 
requests is a 1992 memorandum from John Calcagni, titled ``Procedures 
for Processing Requests to Redesignate Areas to Attainment'' 
(``Calcagni Memo'').\45\ The Calcagni Memo outlines the key elements of 
a maintenance plan, which include an attainment emissions inventory, 
maintenance demonstration, monitoring and verification of continued 
attainment, and a contingency plan.
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    \45\ Memorandum dated September 4, 1992, from John Calcagni, 
Director, Air Quality Management Division, EPA, to EPA Regional 
Office Air Division Directors, Subject: ``Procedures for Processing 
Requests to Redesignate Areas to Attainment.''
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    Maintenance plan submittals are SIP revisions, and therefore, the 
EPA is obligated under CAA section 110(k) to approve them or disapprove 
them depending upon whether they meet the applicable CAA requirements 
for such plans.

V. Evaluation of the Coso Junction Second Maintenance Plan

A. Emissions Inventories Overview

    A maintenance plan for the PM10 NAAQS should include an 
inventory of direct PM10 emissions in the area.\46\ The 
inventory should be consistent with the EPA's most recent guidance on 
emissions inventories for nonattainment areas available at the time; 
must be comprehensive, including emissions from stationary point 
sources, area sources, and mobile sources; and must be based on actual 
emissions during the appropriate season, if applicable.\47\
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    \46\ PM10 precursor emissions should also be included 
depending upon the contribution of secondary particulate matter to 
high ambient PM10 concentrations in the area. In this 
instance, an inventory of PM10 precursor emissions is not 
required because PM10 precursor controls were not relied 
upon to achieve attainment of the PM10 NAAQS in the CJPA 
nor are they relied upon to demonstrate maintenance of the NAAQS 
(see Coso Junction Second Maintenance Plan, sections 2 and 4, and 75 
FR 36023, 36027). While not required, the CARB Staff Report 
submitted with the Coso Junction Second Maintenance Plan includes 
inventories of NOX, SOX, ROG, and ammonia in 
Inyo County for 2008, the base year of the first maintenance plan, 
and for 2030, the horizon year for the Coso Junction Second 
Maintenance Plan (``Table 1. Inyo County Annual Average Day 
PM10 and Precursor Emissions (ton/day)'').
    \47\ CAA section 172(c)(3).
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    The specific PM10 emissions inventory requirements are 
set forth in the Air Emissions Reporting Requirements rule,\48\ which 
requires that emissions inventories report filterable and condensable 
components, as applicable.\49\ The EPA has provided additional guidance 
for developing PM10 emissions inventories in 
``PM10 Emissions Inventory Requirements,'' EPA-454/R-94-033 
(September 1994) and ``Emissions Inventory Guidance for Implementation 
of Ozone and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations'' (May 2017).
---------------------------------------------------------------------------

    \48\ 40 CFR part 51, subpart A.
    \49\ 40 CFR 51.15(a)(1)(vii). The primary emissions source in 
the CJPA is windblown dust. Therefore, reporting condensible 
components of PM10 was not applicable in this plan.
---------------------------------------------------------------------------

    The Coso Junction Second Maintenance Plan includes inventories for 
total primary PM10 for the years 2008 (the base year of the 
first maintenance period), 2020 (the base year of the second 
maintenance period), and 2030 (the final year of the second maintenance 
period) as summarized in Table 2 of this document and further detailed 
in Appendix C of the Plan.\50\

[[Page 19039]]

The 2020 emissions inventory represents current emissions and was used 
to project emissions through 2030, as discussed further in Section I.B 
of this document. CARB and the District developed the PM10 
emissions inventories based on the methods and assumptions presented in 
detail in Appendix C of the Plan and summarized herein.
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    \50\ Coso Junction Second Maintenance Plan, Appendix C consists 
of an email memorandum dated June 9, 2021, from Emily Weissinger and 
Julia Lester, Ramboll US Consulting, Inc., to Ann Logan, GBUAPCD, 
Subject: ``24-Hour PM10 Emissions Inventory for the 2nd 
Maintenance Plan for the Coso Junction Planning Area, Inyo County, 
California.'' Appendix C provides emission analyses for the years 
2020-2030.
---------------------------------------------------------------------------

    The District forecasts that the PM10 precursors nitrogen 
oxides (NOX), sulfur oxides (SOX), volatile 
organic compounds (VOCs),\51\ and ammonia will decline in Inyo County 
from 2008 to 2030; however, this small decline does not influence 
attainment.\52\ As discussed in Section 4 of the Plan, the emissions 
estimates from windblown dust from open areas constitute over 98 
percent of the PM10 emissions inventory for 2020 and 2030. 
Due to the nature of exceedances in the CJPA, the Coso Junction 
maintenance demonstration is based entirely on emissions of directly 
emitted PM10 pollution. Thus, the EPA review focuses on 
direct PM10 emissions estimates and does not include an in-
depth analysis of the District's emissions estimates for 
PM10 precursor emissions.
---------------------------------------------------------------------------

    \51\ Some California air quality plans use the term reactive 
organic gases (ROG) instead of VOC. The terms cover essentially the 
same compounds, and herein we use the term VOC.
    \52\ See CARB Staff Report Table 1, ``Inyo County Annual Average 
Day PM10 and Precursor Emissions (tons/day).''
---------------------------------------------------------------------------

    The emissions inventories in the Plan include PM10 
estimates from all source categories the District deems relevant i.e., 
stationary sources, entrained dust from vehicle travel, windblown dust 
from unpaved roads, windblown dust from open areas, and mobile 
sources.\53\ The District did not include windblown dust sources within 
the CJPA in the previous 2010 Maintenance Plan inventories because it 
considered the dust from Owens Lake to be a natural source, and the 
inventory was designed to include only emissions from anthropogenic 
sources. The District included this source in the inventories for the 
Coso Junction Second Maintenance plan due to the magnitude of the 
source of windblown dust contribution to current inventories.\54\
---------------------------------------------------------------------------

    \53\ Coso Junction Second Maintenance Plan, Section 4, 
``Emissions Inventory.''
    \54\ See CARB Staff Report, ``Attainment Year Emission 
Inventory.'' Windblown dust accounts for 98.2 percent of the current 
emissions inventories.
---------------------------------------------------------------------------

1. Stationary Sources
    As discussed in Section 4.1 and Appendix C of the Coso Junction 
Second Maintenance Plan, the District used information in District and 
federal Title V permit files as well as reporting from facilities to 
develop direct PM10 emissions estimates for stationary point 
sources. The District calculated daily annual average values by 
dividing the total annual estimated PM10 emissions from each 
site by 365 days.\55\ There are five stationary sources that emit an 
annual average of at least 50 pounds of PM10 per day located 
within the CJPA: Coso Energy Developers, Twin Mountain Rock Venture, 
China Lake Naval Air Weapons Station, Southwest Pumice, LLC, and Bowman 
Asphalt, Inc.\56\
---------------------------------------------------------------------------

    \55\ Unpaved road and haul road emissions for permitted sources 
are included in the daily emissions for each facility.
    \56\ These sources are listed in descending order of annual 
averages of PM10 emissions in pounds per day and are the 
following: 289 pounds per day, 235 pounds per day, 191 pounds per 
day, 185 pounds per day, and 86 pounds per day of PM10, 
respectively.
---------------------------------------------------------------------------

    The District does not expect a significant increase in stationary 
source emissions through 2030 because 97 percent of the land in the 
CJPA is federally controlled and little of the remaining land is 
undeveloped and/or zoned for commercial or industrial uses needed for 
substantial stationary source operation. Consequently, the District 
concludes new stationary sources are unlikely to be built in the CJPA. 
Additionally, the District observes that the construction of any major 
sources or major modifications to existing facilities will be subject 
to the District's new source review rules, although it notes it has no 
knowledge of any planned expansions in the existing stationary source 
facilities.\57\ Finally, the District notes that new minor sources or 
sources that wish to undergo minor modifications must obtain District 
Permits to Operate, which include provisions to ensure protection of 
and compliance with the NAAQS.
---------------------------------------------------------------------------

    \57\ GBUAPCD Rule 209-A, ``Standards for Authorities to 
Construct'' (adopted May 12, 1993) and Rule 216, ``New Source Review 
Requirements for Determining Impact on Air Quality'' (adopted March 
10, 1976).
---------------------------------------------------------------------------

2. Re-Entrained Road Dust
    Fugitive emissions from re-entrained dust from vehicle travel 
result when dust on roadways is disturbed by vehicle activity and re-
entrained into the air. The District calculated dust emissions 
generated from paved and unpaved roads separately.\58\
---------------------------------------------------------------------------

    \58\ For detailed explanations of the calculations for paved 
roads and unpaved roads, see Coso Junction Second Maintenance Plan, 
Section 4.2 and Appendix C.
---------------------------------------------------------------------------

    For paved roads, the District calculated emissions using CARB's 
California Emissions Projection Analysis Model (CEPAM) 2016v1.05 
emissions inventory for paved road dust in Inyo County, as described in 
Section 4.2 and Appendix C of the Plan.\59\ Using the method described 
in Appendix C, the District used geographic information systems to 
determine that 6.5 percent of the total paved road length in Inyo 
County is located within the CJPA.\60\ This factor was applied to the 
Inyo County emissions data obtained from CEPAM to estimate the 
PM10 dust emissions resulting from paved roads within the 
CJPA.
---------------------------------------------------------------------------

    \59\ CEPAM2016v1.05 was the most recent version of the CEPAM 
model available during SIP development and when the SIP was 
submitted in 2021. It has since been updated to CEPAM 2019 v1.03.
    \60\ Coso Junction Second Maintenance Plan, Appendix C, Figure 1 
and Figure 2.
---------------------------------------------------------------------------

    Estimated PM10 emissions from re-entrained road dust 
from unpaved roads is based on an adjusted emissions factor calculated 
by the methodology in the EPA's Compilation of Air Pollution Emission 
Factors, AP-42, Section 13.2.2 and is described in detail in Section 
4.2 and Appendix C of the Plan.\61\ The District applied the adjusted 
emissions factor of 0.76 pounds per vehicle miles traveled to estimated 
vehicle traffic on unpaved roads to calculate emissions.\62\
---------------------------------------------------------------------------

    \61\ EPA, ``AP-42, Fifth Edition Compilation of Air Pollutant 
Emissions Factors, Volume 1: Stationary Point and Area Sources, 
Section 13.2.2 Unpaved Roads,'' November 2006.
    \62\ Vehicle traffic on unpaved roads was calculated assuming an 
average of 2 trips per day along 50 miles of regularly traveled 
unpaved public roads in the CJPA, consistent with the 2010 
Maintenance Plan. This assumption is reasonable considering the 
sparse population of the CJPA and that most of the unpaved roads are 
located on federally controlled land where access and development 
are restricted. Coso Junction Second Maintenance Plan, p. 17.
---------------------------------------------------------------------------

3. Windblown Dust
    Windblown dust is generated when wind moves across open areas and 
unpaved roads and can contribute to ambient PM10. Potential 
windblown dust emissions from all unpaved roads and open areas across 
the CJPA were estimated to determine its contribution to ambient 
PM10, consistent with other planning areas in Inyo County.
    The District applied an emission factor to the estimated area of 
unpaved roads within the CJPA to estimate emissions from windblown dust 
from unpaved roads.\63\ The methodology is

[[Page 19040]]

described in the District's 2010 technical memorandum and is consistent 
with other SIPs in Inyo County, such as the 2016 Owens Valley Planning 
Area PM10 State Implementation Plan, (``2016 Owens Valley 
SIP'').\64\
---------------------------------------------------------------------------

    \63\ Coso Junction Second Maintenance Plan, Appendix C. An 
emission factor of 0.0241 tons/acre/year for ``barren'' land uses 
was applied to the unpaved roadway area of the estimated 675 miles 
of unpaved roads in the CJPA, with an assumed roadway width of 20 
feet.
    \64\ See 81 FR 89407, 89411 (December 12, 2016) and GBUAPCD 
technical memorandum dated May 3, 2010, ``Unpaved Road Dust Inyo 
County (Revised).''
---------------------------------------------------------------------------

    Windblown dust emissions from open areas vary with the category of 
land use, with some surfaces more emissive than others. The land use 
types with the potential to emit PM10 in the CJPA are 
developed or urban areas, shrublands, forests, and barren land. The 
District estimated the area of each of these land use types using the 
2011 National Land Cover Database and adjusted the total to remove 
acreage related to unpaved roads, as these are emissions that are 
already accounted for.\65\ Emission factors for each land use type were 
multiplied by the acreages of the corresponding land use type.\66\ This 
methodology is described in detail in Appendix C of the Plan, and is 
consistent with other SIPs in Inyo County, such as the 2016 Owens 
Valley SIP.\67\
---------------------------------------------------------------------------

    \65\ Available at https://data.nal.usda.gov/dataset/national-
land-cover-database-2011-nlcd-
2011#:~:text=National%20Land%20Cover%20Database%202011%20%28NLCD%2020
11%29%20is,across%20the%20United%20States%20from%202001%20to%202011. 
Since the submission of this plan, newer landcover products became 
available, however no significant differences were observed within 
the CJPA when comparing the newer landcover data to the 2011 
landcover data.
    \66\ Emission factors for urban areas, shrublands, forest, and 
barren land are 0.0001, 0.0272, 0.0034, and 0.0241 respectively.
    \67\ See 81 FR 89407, 89411.
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4. Mobile Sources
    The District calculated emissions from on-road mobile sources, 
which include tailpipe emissions, tire wear, and brake wear using 
CARB's EMFAC2017 model for Inyo County.\68\ The District further 
estimated emissions generated within the CJPA by adjusting the total 
Inyo County emissions by the same factor used to calculate re-entrained 
road dust from paved roads (6.5 percent).\69\
---------------------------------------------------------------------------

    \68\ EMFAC is short for EMission FACtor. The EPA approved 
EMFAC2017 for SIP development and transportation conformity purposes 
in California on August 15, 2019. 84 FR 41717. EMFAC2017 was the 
most recently approved version of the EMFAC model that was available 
at the time of preparation of the Coso Junction Second Maintenance 
Plan.
    \69\ Coso Junction Second Maintenance Plan, Appendix C, Table 6.
---------------------------------------------------------------------------

    The category of off-road mobile sources includes planes, trains, 
and farm and construction equipment and was estimated for the entirety 
of Inyo County at 0.017 tons per day using CEPAM.\70\ Approximately 
half of these county level emissions were identified as resulting from 
commercial aircraft. The CJPA has no commercial airports or identified 
agricultural acreage. Therefore, off-road mobile sources for the CJPA 
were excluded as negligible from this inventory, and not included in 
the analysis for maintenance.
---------------------------------------------------------------------------

    \70\ CEPAM2016v1.05 was the most recent version of the CEPAM 
model available during SIP development and when the SIP was 
submitted in 2021. It has since been updated to CEPAM 2019 v1.03.
---------------------------------------------------------------------------

5. Emissions Summary
    Based on the emission estimates for the year 2020 as shown in Table 
2 of this document, the District finds that windblown dust from open 
areas accounts for over 98 percent of total PM10 emissions 
in CJPA.\71\ The second highest source of emissions comes from 
stationary sources, which contribute 1.3 percent of the total 
PM10 emissions in the CJPA. Windblown dust from unpaved 
roads, entrained dust from vehicle travel, and mobile source emission, 
together contribute less than 0.5 percent of the total PM10 
emissions.\72\
---------------------------------------------------------------------------

    \71\ Coso Junction Second Maintenance Plan, Table 4, ``Emissions 
Inventory Summary for the Coso Junction PM10 Planning 
Area.''
    \72\ Windblown dust from unpaved road contributes 0.29 percent 
(0.11 tons/day), entrained dust from vehicle travel contributes 0.16 
percent (0.06 tons/day), and mobile sources contribute 0.02 percent 
(0.01 ton/day) of the total PM10 emissions in the CJPA.

                        Table 2--Coso Junction PM10 Emission Inventory, 2008, 2020, 2030
                                              [Annual average, tpd]
----------------------------------------------------------------------------------------------------------------
                        Emissions source                               2008            2020            2030
----------------------------------------------------------------------------------------------------------------
Stationary Sources..............................................            0.64            0.49            0.49
Entrained Dust from Vehicle Travel..............................            0.09            0.06            0.06
Mobile Sources..................................................            0.01            0.01            0.01
    Total.......................................................            0.74            0.56            0.56
Windblown dust--unpaved roads...................................  ..............            0.11            0.11
Windblown dust--Open Areas......................................  ..............           36.34           36.34
    Total including windblown dust..............................  ..............           37.01           37.01
----------------------------------------------------------------------------------------------------------------
Source: Coso Junction Second Maintenance Plan, Table 4 and Appendix C.
Totals may not add up due to rounding.
The 2010 Maintenance plan did not include windblown dust in the Plan's emissions inventory. The missing values
  are represented here with a hyphen.

    Due to the sparse population of the CJPA, and the fact that over 97 
percent of land in this maintenance area is federally controlled and 
operated, the District concludes that future projected growth of 
emissions and population in the CJPA is unlikely and would be limited 
in scope.\73\ The majority of unpaved roads and open areas within the 
CJPA are located on federally controlled lands, where access and 
development are limited to the public.\74\ In addition, any substantive 
development on federal lands is subject to general conformity 
requirements under District Regulation XIII.\75\ Due to these reasons, 
the District has determined that emissions in the CJPA will remain 
relatively constant over the 2020-2030 maintenance period.
---------------------------------------------------------------------------

    \73\ The 2020 US census showed a population of 241 people living 
in the CJPA, approximately 1.3 percent of the 17,900 people living 
in Inyo County. While this number did grow from the 2010 US Census 
of 64 people, the population remains a small portion of Inyo County. 
Further population growth is also limited by the lack of land 
available for development.
    \74\ Coso Junction Second Maintenance Plan, Appendix C, Figure 
2.
    \75\ GBUAPCD, Regulation XIII, ``General Conformity,'' adopted 
October 5, 1994.
---------------------------------------------------------------------------

    The EPA believes the selection of the 2020 base year inventory is 
appropriate given that it is the most recent emissions inventory 
associated with the triennial reporting schedule required under the Air 
Emissions Reporting Requirements rule. Moreover,

[[Page 19041]]

preparation of an annual average daily inventory, as opposed to a 
seasonal or episodic inventory, is appropriate given that elevated 
PM10 concentrations in CJPA do not exhibit a clear seasonal 
or episodic pattern. Based on our review of the documentation provided 
with the plan, we are proposing to find that the 2020 emissions 
inventory for direct PM10 is based on reasonable assumptions 
and methodologies, and that the inventory is comprehensive, current, 
accurate, and consistent with applicable CAA provisions and the 
Calcagni Memo, and are therefore proposing that the 2020 inventory is 
acceptable for use in demonstrating maintenance of the PM10 
NAAQS.

B. Maintenance Demonstration

    Section 175A(a) of the CAA requires that the maintenance plan 
``provide for the maintenance of the national primary ambient air 
quality standard for such air pollutant in the area concerned for at 
least 10 years after the redesignation.'' A state may generally 
demonstrate maintenance of the NAAQS by either showing that future 
emissions of a pollutant or its precursors will not exceed the level of 
the attainment inventory, or by conducting modeling that shows that the 
future mix of sources and emissions rates will not cause a violation of 
the NAAQS.\76\ Projected emissions inventories for future years must 
account for, among other things, the ongoing effects of economic growth 
and adopted emissions control requirements, and the inventories are 
expected to be the best available representation of future emissions. 
The plan submission should include documentation explaining how the 
state calculated the emissions data for the base year and projected 
inventories.
---------------------------------------------------------------------------

    \76\ Calcagni Memo, pp. 9-11.
---------------------------------------------------------------------------

    In the Coso Junction Second Maintenance Plan, the District 
demonstrates continued maintenance of the PM10 NAAQS by 
projecting the direct PM10 emissions in the area through 
2030 and showing that future emissions of PM10 will not 
exceed the level of the attainment inventory. As discussed in Section 
V.A of this document, the Plan includes emissions inventories 
representing actual emissions in 2020 (the Plan's base year) and 
projected emissions through 2030 (the final year of the second 
maintenance period) for sources in the CJPA.\77\
---------------------------------------------------------------------------

    \77\ Coso Junction Second Maintenance Plan, Section 4 and 
Appendix C.
---------------------------------------------------------------------------

    The District derived projected inventories by applying expected 
growth trends for each source category based on data that reflect 
historical trends, current conditions, and recent economic and 
demographic forecasts with expected emissions reductions resulting from 
adopted control measures to the base year inventory. For the Coso 
Junction Second Maintenance Plan, emission methodologies used in the 
2010 Maintenance Plan were reviewed by the District and updated as 
appropriate to generate emissions for this Plan. Appendix C of the Plan 
documents the methods and assumptions used to develop the emissions 
projections upon which the maintenance demonstration relies and 
presents the detailed source category-specific estimates for each of 
the analysis years.
    As discussed in Section I.B of this document, the emissions 
reductions from Owens Lake were the primary factor leading to 
attainment for the CJPA, and Owens Lake is the paramount source of 
emissions that must be addressed to ensure maintenance for the 
area.\78\ District Rule 433, ``Control of Particulate Emissions at 
Owens Lake,'' \79\ provides a federally enforceable regulatory 
mechanism to ensure continued success of the established dust control 
strategy on Owens Lake, and ensures that emissions from Owens Lake do 
not cause or contribute to exceedances in the CJPA.\80\
---------------------------------------------------------------------------

    \78\ 75 FR 36023, 36030.
    \79\ Rule 433 was adopted by GBUAPCD on April 13, 2016, and 
approved by EPA on December 28, 2016 (81 FR 95473).
    \80\ Coso Junction Second Maintenance Plan, Section 6.1 and 
Appendix D.
---------------------------------------------------------------------------

    For these reasons, and due to the unique nature of the CJPA, the 
EPA believes that the District's determination that the total daily 
emissions of PM10 from sources within the CJPA will remain 
constant at 37.01 tons per day from 2020 through 2030 is reasonable. We 
agree that the projected emissions inventories for direct 
PM10 for years 2020 through 2030 are based on reasonable 
methods, growth factors, and assumptions, and are based on the most 
current and accurate information available to CARB and GBUAPCD at the 
time the Plan and its inventories were being developed. We also agree 
that the Coso Junction Second Maintenance Plan provides an adequate 
basis to demonstrate maintenance of the PM10 NAAQS within 
the CJPA through 2030. Consequently, we are proposing to approve the 
Plan because it demonstrates maintenance of the PM10 NAAQS 
for more than 10 years after the expiration of the first 10-year 
maintenance plan, in accordance with section 175A(b) of the CAA.

C. PM10 Air Quality Monitoring Network

    After an area has been redesignated, the state should continue to 
operate an appropriate air quality monitoring network, in accordance 
with 40 CFR part 58, to verify the attainment status of the area.\81\
---------------------------------------------------------------------------

    \81\ Calcagni Memo, p. 11.
---------------------------------------------------------------------------

    As discussed in Section I.B of this document, GBUAPCD monitors 
ambient concentrations of PM10 in the CJPA near the State of 
California Coso Junction Rest Area in the Rose Valley.\82\ In Section 
10 of the Coso Junction Second Maintenance Plan, the District commits 
to continue to operate and maintain a PM10 ambient air 
quality monitor in the CJPA in accordance with 40 CFR parts 50, 53, and 
58 to verify the attainment status of the area. The monitoring will 
also allow the District to notify the public during air pollution 
episodes as provided for in District Rule 701, ``Air Pollution Episode 
Plan'' and in the District's 2018 Exceptional Events Mitigation Plan 
for the CJPA.\83\ Data collected by the monitoring network are also 
needed to implement the contingency provisions of the maintenance plan. 
We are proposing that the Coso Junction Second Maintenance Plan 
contains adequate provisions for continued ambient PM10 
monitoring to verify continued attainment through the full maintenance 
period, ending on October 4, 2030.
---------------------------------------------------------------------------

    \82\ AQS Site No. 06-027-1001.
    \83\ GBUAPCD, Rule 701, ``Air Pollution Episode Plan,'' adopted 
March 3, 2014.
---------------------------------------------------------------------------

D. Verification of Continued Attainment

    The EPA recommends that the state verify continued attainment 
through methods in addition to the ambient air monitoring program, 
e.g., through periodic review of the factors used in development of the 
attainment inventory to show no significant change.\84\ GBUAPCD commits 
to review the emissions inventory inputs on an annual basis and, if the 
District finds that these inputs have changed significantly, to request 
that CARB update the existing inventory and to compare the revised 
inventory with the inventories in the Coso Junction Second Maintenance 
Plan.\85\ Additionally, the District commits to updating its calculated 
three-year design value for the CJPA annually. This design value will 
also be included in the annual network monitoring plan submitted to the 
EPA to confirm the area continues to meet the PM10 NAAQS. We 
are proposing to find that the District's

[[Page 19042]]

commitments are acceptable to verify continued attainment of the 
PM10 NAAQS.
---------------------------------------------------------------------------

    \84\ Calcagni Memo, p. 11.
    \85\ Coso Junction Second Maintenance Plan, Section 11.
---------------------------------------------------------------------------

E. Contingency Provisions

    Section 175A(d) of the CAA requires that maintenance plans include 
contingency provisions, as the EPA deems necessary, to promptly correct 
any violations of the NAAQS that occur after redesignation of the area. 
Such provisions must include a requirement that the state will 
implement all measures with respect to the control of the relevant air 
pollutants that were contained in the SIP for the area before 
redesignation of the area as an attainment area. These contingency 
provisions are distinguished from contingency measures required for 
nonattainment areas under CAA section 172(c)(9) in that they are not 
required to be fully adopted measures that will take effect without 
further action by the state for the maintenance plan to be approved. 
However, the contingency provisions of a maintenance plan are an 
enforceable part of the SIP and should ensure that contingency measures 
are adopted expeditiously once they are triggered. The maintenance plan 
should clearly identify the measures to be adopted, include a schedule 
and procedure for adoption and implementation of the measures, and 
contain a specific timeline for action by the state. In addition, the 
state should identify the specific indicators or triggers that will be 
used to determine when the contingency measures need to be implemented.
    The District has adopted a contingency plan to address possible 
future PM10 air quality problems in the CJPA. The 
contingency plan is detailed in Section 7 of the Plan. As noted by the 
District in the Plan, contingency provisions are typically implemented 
when air quality deteriorates beyond a specified level, such as a 
certain number of exceedances of the standard or a violation of the 
standard. In this case, the contingency provisions will be triggered if 
an exceedance of the federal PM10 standard is monitored 
within the CJPA.\86\
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    \86\ An exceedance of the PM10 NAAQS is determined 
when the number of exceedances at the monitor, averaged over three 
years, is greater than 1.05.
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    The contingency plan also includes a screening process that allows 
the District and CARB, subject to the EPA's review, to exclude 
exceedances from the trigger calculation if the agencies collectively 
determine that information developed by the District is sufficient to 
support exclusion. The purpose of the screening process is to 
differentiate between exceedances that are not within the District or 
State control (i.e., exceedances that occur despite the implementation 
of reasonable measures), and exceedances that are within the District's 
or State's control and should be included in the trigger calculation. 
It is important to note that, should the District or State exclude an 
exceedance from the contingency trigger calculation using this process, 
it would not constitute the EPA's concurrence that the exceedance was 
caused by an exceptional event. The exceedance will therefore continue 
to be included in design value calculations for the CJPA unless CARB, 
following opportunity for public comment, submits a request for the EPA 
to concur on the exceedance as an exceptional event pursuant to 40 CFR 
50.14, and the EPA reviews the submittal and formally concurs.
    If an exceedance occurs, the District will start the screening 
process to investigate the cause of the exceedance within 60 days 
following the end of the calendar quarter during which the event 
occurred. An exceedance determined by the District to be caused by or 
significantly contributed to by emissions from the Owens Lake area 
would trigger contingency measures, as outlined in Section 7.1, ``Owens 
Valley Planning Area Contingency Measures,'' of the Coso Junction 
Second Maintenance Plan. In brief, the District will investigate the 
exceedance within 60 days of the end of the calendar quarter in which 
it occurred to determine whether the required control measures on Owens 
Lake were properly implemented in accordance with District Rule 433 or 
if the emissions are from a new source on Owens Lake.\87\ For 
exceedances found to be caused by dust from existing dust control 
areas, the District will order corrective actions no more than 18 
months after the 60 day period of investigation. Exceedances found to 
be caused by dust from a new source on Owens Lake will be subject to 
the contingency provisions under section C of District Rule 433. 
Mitigation of emissions from uncontrolled areas of Owens Lake will be 
addressed as expeditiously as possible by the District under the legal 
constraints of the 2014 Stipulated Judgement, the 2016 Owens Valley 
SIP, and District Rule 433.\88\ Additionally, at least once per year, 
the District will make an additional best available control measure 
contingency determination to evaluate if uncontrolled areas on the 
Owens Lakebed or implemented controls are not sufficient to mitigate 
emissions to attain the NAAQS in the Owens Valley Planning Area.
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    \87\ District Rule 433, ``Control of Particulate Emissions at 
Owens Lake,'' contains contingency measures for the Owens Valley 
Planning Area and provides the following: clearly identified control 
measures, a schedule and procedure for adoption and implementation 
of the measures, a time limit in which to take action, and an 
established threshold that triggers the contingency measures. See 
Coso Junction Second Maintenance Plan, Appendix D.
    \88\ The EPA approved District Rule 433 into the California SIP 
on December 27, 2016 (81 FR 95473).
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    An exceedance determined to be caused by emissions from sources 
located within the CJPA would trigger the contingency provisions 
outlined in Section 7.2, ``Additional Contingency Measures,'' of the 
Coso Junction Second Maintenance Plan. Following the end of the 
calendar quarter in which the exceedance occurs, the District will 
investigate the cause of the exceedance within 60 days. Exceedances 
found to be caused by emissions from local sources already subject to 
District regulations will be promptly addressed no more than 18 months 
after the 60-day period of investigation.\89\ If the exceedance cannot 
be addressed through existing District rules and regulations and is not 
covered by the EPA Exceptional Events Policy, the District will adopt 
and implement additional control measures necessary to meet and 
maintain the NAAQS within 18 months after the 60 day period of 
investigation. Control measures could include expanding existing rules 
or utilizing measures from outside existing rules and regulations to 
achieve the necessary emissions reductions within 18 months.
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    \89\ Table 5 in the Coso Junction Second Maintenance Plan lists 
existing District rules and regulations to control sources of 
PM10.
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    Within 60 days of the end of each calendar quarter, the District 
will provide a list of exceedances that occurred during that previous 
quarter to CARB, identify those exceedances that the District believes 
to be exceedances that are not within the District's or State's 
control, and flag the relevant data and provide an initial description 
in AQS.
    If the District seeks to exclude an exceedance from the contingency 
measures trigger calculation, the District will notify CARB and the EPA 
by submitting an INI. The EPA, CARB, and the District will confer to 
determine whether additional information should be submitted along with 
the INI. The District will submit the INI and any additional requested 
information to CARB and the EPA for review. After review, CARB and the 
EPA will notify

[[Page 19043]]

the District if the Agencies agree that the exceedance appears to be an 
uncontrollable event and therefore will not be counted towards the 
contingency measure trigger calculation, or if the Agencies determine 
that the exceedance was likely caused by an exceptional event and that 
the District must include the event in the contingency measure trigger 
calculation. If the District still considers the event in question to 
be exceptional, the District may then opt to submit a full Exceptional 
Events Demonstration.
    Based on our review of the Coso Junction Second Maintenance Plan, 
as summarized herein, we propose to find that the contingency 
provisions of the Plan clearly identify specific contingency measures, 
contain a triggering mechanism to determine when contingency measures 
are needed, contain a description of the process of recommending and 
implementing contingency measures, and contain specific and appropriate 
timelines for action. We also propose to find that the contingency 
trigger screening process, including the associated EPA review, is 
reasonably designed to distinguish between exceedances that are not 
within the District or State control, and exceedances that are within 
the District's or State's control and for which new or tightened 
control measures might be effective. Thus, we propose to conclude that 
the contingency plan in the Coso Junction Second Maintenance Plan is 
adequate to ensure correction of any violation of the PM10 
NAAQS that occurs after redesignation, as required by section 175A(d) 
of the CAA.

F. Motor Vehicle Emissions Budgets for Transportation Conformity

    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 the NAAQS, (2) worsen the severity of an existing 
violation, or (3) delay timely attainment of any NAAQS or any interim 
milestone.
    Transportation 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 (MPOs) in nonattainment and maintenance areas coordinate 
with state and local air quality and transportation agencies, the EPA, 
FHWA, and 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 (``budgets'') 
contained in submitted or approved control strategy SIPs and 
maintenance plans.\90\
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    \90\ Control strategy SIPs refer plans that contain specific 
strategies for controlling the emissions of and reducing ambient 
levels of pollutants in order to satisfy CAA requirements for 
demonstrations of reasonable further progress and attainment. 40 CFR 
93.101.
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    However, an isolated rural area does not have an MPO and is not 
required to prepare transportation plans or transportation improvement 
programs. Therefore, in isolated rural areas such as the CJPA, 
conformity is determined only when a nonexempt FHWA or FTA project 
needs approval or funding.\91\
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    \91\ 40 CFR 93.109(g)
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    Control strategy SIPs and maintenance plans typically set budgets 
for criteria pollutants and/or their precursors to address pollution 
from cars and trucks. Budgets are generally established for specific 
years and specific pollutants or precursors. PM10 
maintenance plan submittals should identify budgets for transportation-
related PM10 emissions in the last year of the maintenance 
period.\92\
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    \92\ Transportation-related emissions of VOC and NOX 
must also be specified in PM10 maintenance plans if the 
EPA or the state find that transportation-related emissions of one 
or both of these precursors within the nonattainment area are a 
significant contributor to the PM10 nonattainment problem 
and has so notified the MPO and the U.S. Department of 
Transportation (DOT), or the applicable SIP (or SIP revision 
submission) establishes an approved (or adequate) budget for such 
emissions as part of the reasonable further progress, attainment, or 
maintenance strategy. 40 CFR 93.102(b)(2)(iii). Neither of these 
conditions apply to the Coso Junction PM10 maintenance 
area.
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    Section 93.109(f) of EPA's transportation conformity regulation (40 
CFR part 93) states that an area is not required to satisfy a regional 
emissions analysis for a pollutant if the EPA finds that motor vehicle 
emissions of that pollutant are an insignificant contributor to the 
area's air quality problem. To make this demonstration, the submitted 
SIP would have to show that it would be unreasonable to expect that the 
area would experience enough motor vehicle emissions growth in that 
pollutant/precursor for a NAAQS violation to occur. Factors to consider 
in such a demonstration include the percentage of motor vehicle 
emissions in the context of the total attainment plan inventory; the 
current state of air quality as determined by monitoring data for that 
NAAQS; the absence of SIP motor vehicle control measures; and 
historical trends and future projections of the growth of motor vehicle 
emissions.
    In our rulemaking approving the 2010 Maintenance Plan for the CJPA, 
the EPA found the contribution of motor vehicles to be an insignificant 
source of PM10 to the CJPA.\93\ As part of the Coso Junction 
Second Maintenance Plan, GBUAPCD requested that the EPA find that on-
road emissions of PM10 are insignificant for conformity 
purposes, and therefore the District did not submit any motor vehicle 
emissions budgets. The EPA is proposing to approve GBUAPCD's 
insignificance demonstration for the on-road motor vehicle contribution 
of PM10 emissions to the overall PM10 emissions 
in the Coso Junction Second Maintenance Plan. Additionally, in this 
notice, the EPA is initiating the adequacy review process for this 
insignificance finding. The EPA invites the public to comment on the 
adequacy of this insignificance finding as well as other actions the 
EPA is proposing in this notice.
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    \93\ 75 FR 54031.
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    This insignificance finding is based on the following consideration 
of the factors identified in the EPA's transportation conformity 
regulations, as discussed in sections 4 and 8 of the Coso Junction 
Second Maintenance Plan, and on the unique circumstances of the CJPA.
1. The Percentage of Motor Vehicle Emissions in the Context of the 
Total SIP Inventory
    The District calculated the percentage of on-road motor vehicle 
emissions by adding together direct emissions from on-mobile source 
emissions,\94\ entrained dust from vehicle travel on paved roads, and 
entrained dust from vehicle travel on unpaved roads, and dividing the 
sum by the total PM10 emissions including windblown dust. 
These values can be found in Table 2 of this notice. On-road mobile 
emissions constitutes less than 0.2 percent of the PM10 
emissions inventory in the CJPA.\95\ The District attributes this to 
the low population of the CJPA.
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    \94\ Direct emissions from vehicle exhaust tire wear and brake 
wear comprised this source category and accounted for 0.010 tpd of 
the CJPA PM10 emissions inventory
    \95\ Coso Junction Second Maintenance Plan, p. 25.
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2. The Coso Junction Planning Area Is Attaining the PM10 
NAAQS
    As discussed in Section 3 of the Coso Junction Second Maintenance 
Plan and

[[Page 19044]]

in Section I.C.2 of this document, the 2018-2020 PM10 
monitoring data show that the CJPA is in attainment of the 
PM10 NAAQS. The District observes that this current state of 
air quality coincides with the improvements in the Owens Valley area as 
emissions from Owens Lake have been mitigated over time, and notes that 
these continual improvements in air quality have resulted in annual 
average PM10 concentrations of less than 20 [micro]g/m\3\ 
over the past ten years.
3. Motor Vehicle Control Measures Were Not Adopted for the Purpose of 
Bringing the Area Into Attainment
    As discussed in Section V.A of this document, the control measures 
relied upon in the Coso Junction Second Maintenance Plan are primarily 
related to windblown dust, which accounts for over 98 percent of the 
PM10 emissions in the CJPA. As discussed in Section 4 of the 
Coso Junction Second Maintenance Plan and in Section V.A of this 
notice, on-road mobile emissions in the CJPA, including exhaust, tire 
wear, brake wear, and re-entrained road dust from paved and unpaved 
roads, make up less than 0.2 percent of the daily PM10 
emissions in the CJPA.\96\ There are currently no GBUAPCD adopted motor 
vehicle control measures specific to the CJPA. Any national and 
statewide motor vehicle emission control measures that may apply would 
contribute to reductions in motor vehicle related PM10 
emissions in the CJPA, which as noted previously, amount to less than 
0.2 percent of the total PM10 emissions inventory.
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    \96\ Table 6 in the Coso Junction Second Maintenance Plan 
provides specific breakdowns of each category.
---------------------------------------------------------------------------

4. Historical Trends and Future Projections Indicate Motor Vehicle 
PM10 Emissions Are Consistent Over Time
    Historical on-road mobile emissions have constituted a tiny 
fraction of the overall PM10 emissions inventory in the 
CJPA.\97\ The District attributes this to the low population of the 
CJPA. Despite some population growth in the area, the population of the 
CJPA occupies only 1.3 percent of the land area of Inyo County, and 
substantial population growth is limited by the high percentage of 
federally controlled land where access, development, or both are 
restricted.\98\ For these reasons, the District states that on-road 
mobile emissions can reasonably be expected to remain relatively small 
and unchanging over the 2020-2030 maintenance period.\99\
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    \97\ In the 2010 Maintenance Plan, on-road mobile emissions 
constituted less than 1 percent of the daily PM10 
emissions (12 of 1478 pounds of PM10 per day), excluding 
windblown dust.
    \98\ According to the 2000 U.S. Census, 102 people lived in 
Pearsonville and Homewood Canyon, which are located at the southern 
end of the CJPA. The 2010 U.S. Census reported a decrease to 61 
people, and the 2020 U.S. Census reports 241 people. Despite the 
population growth, the population still represents less than 2 
percent of Inyo County's population and is not expected to have a 
significant effect on on-road mobile emissions.
    \99\ See Coso Junction Second Maintenance Plan, Section 8.4.
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    Given these factors, we are proposing to find that motor vehicle-
related PM10 emissions are insignificant contributors to 
PM10 in the CJPA and that it would be unreasonable to expect 
that PM10 emissions from motor vehicles would grow enough 
within the CJPA to cause a violation of the PM10 standard. 
If this insignificance finding is finalized as proposed, a regional 
emissions analysis would not be required for PM10 in any 
future conformity determination for the 1987 PM10 NAAQS in 
the CJPA.\100\ The EPA's insignificance finding should, however, be 
noted in any transportation conformity documentation that is prepared 
for this area. Areas with insignificant regional motor vehicle 
emissions for a pollutant or precursor are still required to make a 
conformity determination that satisfies other relevant conformity 
requirements such as fiscal constraint, timely implementation of 
transportation control measures, interagency consultation, and hot-spot 
analyses for projects, if required.
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    \100\ Upon the completion of the adequacy finding, conformity 
can be determined without a regional emissions analysis regardless 
of the finalization of the rest of the items proposed in this 
notice.
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VI. Environmental Justice Considerations

    The EPA performed and reviewed a screening-level analysis using the 
EPA's environmental justice (EJ) screening and mapping tool 
(``EJSCREEN''). Our screening-level analysis included multiple 
environmental and demographic indicators, including the EJSCREEN 
``Demographic Index,'' which is the average of an area's percentage of 
minority and low-income populations. The Demographic Index for the 
southwest portion of Inyo County, which contains the CJPA, is at the 
52nd percentile, compared to the United States as a whole.\101\ The 
results of this analysis are being provided for informational purposes. 
The results of the demographic analysis indicate that, for populations 
within the CJPA, the percentage of people of color (persons who 
reported their race as a category other than White alone (not Hispanic 
or Latino)) is similar to the national average, both at 40 percent. The 
percent of people living below the poverty level in the CJPA is 21 
percent, which is lower than the national average of 30 percent.
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    \101\ Coso Junction PM10 NAA EJSCREEN Report, dated 
January 18, 2023.
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    This proposed action addresses a plan for continued maintenance of 
the 1987 PM10 NAAQS for the CJPA. Approval of this plan does 
not impose any additional regulatory requirements on sources beyond 
those imposed by state law. As discussed in this document, California 
has demonstrated that the CJPA is attaining the 1987 PM10 
NAAQS and the Coso Junction Second Maintenance Plan provides for the 
maintenance of the NAAQS for the reminder of the maintenance period. At 
a minimum, this action would not worsen any existing air quality and is 
expected to ensure the area is meeting requirements to maintain air 
quality standards. Further, there is no information in the record 
indicating that this action is expected to have disproportionately high 
or adverse human health or environmental effects on a particular group 
of people.

VII. Proposed Action and Request for Public Comment

    Under CAA section 110(k)(3), and for the reasons set forth in this 
document, the EPA is proposing to approve the Coso Junction Second 
Maintenance Plan submitted electronically on October 21, 2021, by CARB, 
as a revision to the California SIP. We are proposing to approve the 
maintenance demonstration and contingency provisions as meeting all the 
applicable requirements for maintenance plans and related contingency 
provisions in CAA section 175A, and we are proposing an insignificance 
finding for motor vehicle emissions in the CJPA. Additionally, the EPA 
is also initiating the adequacy process for this insignificance finding 
included in this SIP submission.
    We are soliciting comments on these proposed actions and on the 
adequacy of the maintenance plan's demonstration that motor vehicle 
emissions are insignificant. We will accept comments from the public 
for 30 days following publication of this proposal in the Federal 
Register and will consider any relevant comments before taking final 
action or making an adequacy determination.

VIII. 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

[[Page 19045]]

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 law as meeting 
federal requirements and does not impose additional 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
    In addition, there are no areas of Indian country within the CJPA, 
and the state plan for which the EPA is proposing approval does not 
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. 
Therefore, this proposed action does not have tribal implications and 
would not, if approved, impose substantial direct costs on tribal 
governments or preempt tribal law as specified by Executive Order 13175 
(65 FR 67249, November 9, 2000).
    Executive Order 12898 (Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
Feb. 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on minority populations and low-income 
populations to the greatest extent practicable and permitted by law. 
EPA defines environmental justice (EJ) as ``the fair treatment and 
meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies.'' EPA further defines the term fair treatment to mean that 
``no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.''
    The air agency did not evaluate environmental justice 
considerations as part of its SIP submittal; the CAA and applicable 
implementing regulations neither prohibit nor require an evaluation. 
EPA performed an environmental justice analysis, as is described above 
in the section titled, ``Environmental Justice Considerations.'' The 
analysis was done for the purpose of providing additional context and 
information about this rulemaking to the public, not as a basis of the 
action. Due to the nature of the action being taken here, this action 
is expected to have a neutral to positive impact on the air quality of 
the affected area. In addition, there is no information in the record 
upon which this decision is based that is inconsistent with the stated 
goal of E.O. 12898 of achieving environmental justice for people of 
color, low-income populations, and Indigenous peoples.

List of Subjects in 40 CFR Part 52

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

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

    Dated: March 24, 2023.
Kerry Drake,
Acting Regional Administrator, Region IX.
[FR Doc. 2023-06578 Filed 3-29-23; 8:45 am]
BILLING CODE 6560-50-P